JP2023013969A - Plate-shaped molding - Google Patents

Abstract

[Problem] The object of the present invention is to provide a plate-shaped molded product having finely formed fine convex portions on at least one main surface, with a good appearance. [Solution] The plate-shaped molded product has a plurality of fine convex portions with a height a of 50 to 600 μm on at least one main surface, and is characterized by being injection molded from a methacrylic resin composition having a tensile fracture strain of 1.5% or more and a glass transition temperature (Tg) of 115 to 150°C. [Selected Figures] None

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate-like molded article having fine convex shapes on at least one main surface.

Conventionally, when molding injection-molded products with fine uneven shapes, the entire surface of the mold cavity in contact with the molded product is preheated to a set value above the softening temperature of the resin, and the set value is maintained during the injection process. Then, an injection molding method is used in which the heating is completed and the mold is cooled when switching to the cooling step. In such an injection molding method, residual stress is reduced by heating the mold cavity surface to a set value above the softening temperature of the resin before the start of the injection process, and molding defects such as deformation, cracks, and deterioration of birefringence are reduced. It is possible to solve the problem (for example, Patent Documents 1 to 5).

JP-A-10-80940 JP-A-10-80938 JP-A-11-58476 JP-A-63-95919 JP 2010-264703 A

In the case of obtaining a molded product with a high convex portion of a fine shape by the above method, it is necessary to fill the resin sufficiently to the inside of the concave portion of the mold for shaping the convex shape. The more the resin penetrates into the surface, the higher the transferability and the better the appearance of the molded product. On the other hand, when the height of the convex portion of the fine shape is high (the depth of the concave portion of the mold is deep), the physical resistance increases when the molded product is taken out. The present inventors have made it clear from the studies by the present inventors that when the release resistance at the time of release of the molded product increases, defects such as breakage and deformation of the finely shaped portions occur, and the appearance deteriorates. Moreover, when the molded article is used for optical purposes, there is a problem that the optical properties are degraded.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a plate-shaped molded article having fine convex portions on at least one main surface, in which the fine portions are well formed and the appearance is good. for the purpose.

The present inventors have found that a plate-shaped molded article containing a methacrylic resin composition having a plurality of fine convex portions on at least one main surface and having a glass transition temperature (Tg) within a specific range, the plate The present inventors have found that the above problems can be solved by setting the value of the tensile breaking strain of the methacrylic resin composition constituting the shaped molded product to a specific range, and have completed the present invention.

That is, the present invention is as follows.
[1] A plate-shaped molded article having a plurality of fine convex portions with a height a of 50 to 600 μm on at least one main surface, a tensile fracture strain of 1.5% or more, and a glass transition temperature ( A plate-like molded product, characterized by being obtained by injection molding a methacrylic resin composition having a Tg) of 115 to 150°C.
[2] On the main surface having the fine convex portions, the ratio b/a of the pitch b of the fine convex portions to the height a of the fine convex portions is 0.1 to 1.0. , the plate-shaped molded article according to [1].
[3] The plate-like molded article according to [1] or [2], wherein the in-plane retardation of the main surface having the fine convex portions is 100 nm or less.
[4] obtained by heating the surface temperature of the mold to the glass transition temperature (Tg) of the methacrylic resin composition or higher and then injection-filling the methacrylic resin composition into the mold, [1] The plate-like molded article according to any one of -[3].
[5] The plate-like molded article according to any one of [1] to [4], which is a member for an aerial display.

According to the present invention, it is possible to obtain a plate-like molded article having fine convex portions on at least one main surface, in which the fine portions are well formed and the appearance is good.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows an example of the plate-shaped molded product of this embodiment, (A) is a top view when the main surface which has a convex-shaped part is made into an upper surface, (B) is a side view. 1. It is a partial cross-sectional view which shows the shape (triangular pyramid) of the convex-shaped part of the plate-shaped molded product shown in FIG. It is a diagram showing another example of the plate-shaped molded article of the present embodiment, (A) is a top view when the main surface having a convex portion is the top, (B) is a side view, (C) is a convex Fig. 10 is a perspective view of a profile; FIG. 4 is a partial cross-sectional view showing the shape (truncated quadrangular pyramid) of the convex portion of the plate-like molded product shown in FIG. 3 ; FIG. 4 is a diagram showing optical paths when the plate-shaped molded articles obtained in Examples and Comparative Examples are used as light direction changing elements. FIG. 2 is a layout diagram of equipment used when evaluating characteristics when the plate-shaped molded articles obtained in Examples and Comparative Examples are used as light direction changing elements. FIG. 7 is a plan view of the USAF Target 7 used in FIG. 6 when viewed from the X-axis direction;

Hereinafter, a mode for carrying out the present invention (hereinafter referred to as "this embodiment") will be described in detail, but the present invention is not limited to the following description, and various It can be modified and implemented.

(Plate molded product)
Hereinafter, the plate-like molded product of this embodiment will be described with reference to the drawings. The plate-shaped molded article (hereinafter also simply referred to as "molded article") of the present embodiment has two main surfaces, and at least one of the two main surfaces has a height a of 50 to 50. It contains a methacrylic resin composition having a plurality of fine convex portions of 600 μm, a tensile breaking strain of 1.5% or more, and a glass transition temperature (Tg) of 115 to 150 ° C. do.

The plate-like molded product of the present embodiment has a plurality of fine convex portions (hereinafter also referred to as "fine convex portions" or simply "convex portions") on at least one of the two main surfaces. and the height a of the convex portion is 50 to 600 μm.
Further, as will be described later, the ratio b/a of the pitch b of the convex portions to the height a of the convex portions is preferably 0.1 to 1.0. By configuring in this way, the molded product can be cleanly released from the mold while maintaining a good mold transfer rate. The shape and the like of the plate-like molded product of this embodiment will be described in detail below.

The shape of the fine convex portion formed on at least one of the main surfaces is not particularly limited, and may include a triangular pyramid, a square pyramid, a polygonal pyramid such as a pentagonal pyramid, a cone, an elliptical pyramid, a half cone, a half elliptical pyramid, and an elongated pyramid. Curved pyramids such as circular pyramids (cones having a cross section in the shape of a pair of parallel straight lines connected by semicircles at both ends), polygonal pyramids such as triangular pyramids, square pyramids, and pentagonal pyramids, truncated cones, and ellipses Curved frustums such as frustums, semi-conical frustums, semi-elliptical frustums, elliptical frustums (truncated bodies having a cross section in the shape of a pair of parallel straight lines connected by a semicircle at both ends), triangular prisms, square prisms ( Cubes, rectangular parallelepipeds, etc.), polygonal prisms such as pentagonal prisms, cylinders, elliptical cylinders, semi-cylindrical cylinders, semi-elliptical cylinders, oval cones (columns with a cross section in the shape of a pair of parallel straight lines connected at both ends with semicircles) curved columns, dome shapes (structures with hemispheres, quadrants, aspherical surfaces, etc., structures in which the cross-sectional area when cut in the axial direction gradually decreases as it goes upward in the axial direction), etc. . In the case of a polygonal pyramid, a polygonal prism, etc., the corners may be rounded. Moreover, the shape of the side surface of the convex portion may be flat or curved.
The shape of these convex portions may be of only one type, or may be a combination of a plurality of types of shapes, but preferably only one type.

FIG. 1 shows an example of a plate-like molded article of this embodiment, (A) is a top view, and (B) is a side view. The plate-like molded product 1 shown in FIG. 1 has two main surfaces 11 and 12, and a plurality of fine convex portions 14 are formed only in a region 13 of the main surface 11. As shown in FIG. It should be noted that the dimensions shown in FIG. 1 are merely examples and are not limiting.

FIG. 2 shows the shape of the fine protrusions 14 formed on the plate-like molded product 1 shown in FIG. 1, and the shape of the protrusions 14 is a triangular pyramid.

In addition, FIG. 3 shows another example of the plate-shaped molded product of the present embodiment, (A) is a top view, (B) is a side view, and (C) is a perspective view of the fine convex portion 24. is. In the plate-like molded product 2 shown in FIG. 3, a plurality of fine convex-shaped portions 24 are formed only in a region 23 of the principal surface 21 . It should be noted that the dimensions shown in FIG. 3 are merely examples and are not limiting.

FIG. 4 shows the shape of the fine convex portions 24 formed on the plate-like molded product 2 shown in FIG.

The convex portions 14 (24) may be arranged linearly, curvedly, in dots, or the like. 1(A) and 3(A), the convex portion 14 (24) is arranged only in the region 13 (23) of one main surface 11 (21). (21) may be arranged on the entire surface. Moreover, the convex portion 14 (24) may be arranged on the entire surface of both main surfaces, or may be arranged only on a partial region of each of both main surfaces, or may be arranged on the entire surface of one of the main surfaces. and may be arranged only in a partial region of the other main surface.

In the main surfaces 11 and 21 having the fine convex portions 14 (24), the ratio b/a of the pitch b to the height a of the fine convex portions 14 (24) is 0.1 to 1.0. is preferably 0.2 to 1.0, more preferably 0.3 to 1.0. When b/a is within the above range, the molded products 1 and 2 tend to be released cleanly from the mold while maintaining an extremely good mold transfer rate.
The above b/a is an average value of values obtained by measuring the height and pitch of five or more convex portions 14 (24). Therefore, as long as b/a is within the above range, the height and pitch of each convex portion 14 (24) may be changed arbitrarily.

The height a of the convex portion 14 (24) is 50 to 600 μm, preferably 100 to 600 μm, more preferably 200 to 600 μm, still more preferably 300 to 600 μm. As the height a of the convex portion 14 (24) increases, the concave portion of the mold for forming the convex shape becomes deeper, so the release resistance increases when the molded product is removed from the mold. Defects tend to occur easily, but if the height a of the convex portion 14 (24) is within the above range, a molded product with a good appearance can be obtained. If the height a of the convex portion 14 (24) is higher than this range, it does not mean that a molded product having good appearance and optical characteristics cannot be obtained at all, but the resin tends to be easily released from the mold. Therefore, considering the mass productivity, it is preferable to be within the above range.
In this specification, the "height of the convex portion" is a molded product measured based on a flat portion of one main surface 11 (21) parallel to a flat portion of the other main surface 12 (22). The height a means the highest value among the heights in the thickness direction of 1 (2), and the height a is the average value of the heights of five or more convex portions 14 (24). For example, as shown in FIG. 2, when the shape of the convex portion 14 is a cone, it means the height to the apex of the cone. The height of the convex portion 14 (24) when there is no flat portion parallel to the flat portion of the other main surface 12 (22) on one main surface 11 (21) is the height of the molded product 1 (2). The height in the thickness direction of the convex portion 14 (24) with respect to the average thickness may be the highest value. In addition, when there is no planar portion on both of the two main surfaces 11 (21) and 12 (22) (the convex portions are arranged on the entire surface of both main surfaces), the convex shape of either main surface Also for the portion 14 (24), the height in the thickness direction of the convex portion 14 (24) with respect to the average thickness of the molded product 1 (2) may be set to the highest value.

The pitch b of the convex portions 14 (24) is preferably in the range of 100-500 μm, more preferably in the range of 150-350 μm, and even more preferably in the range of 180-300 μm. When the pitch b of the convex portions 14 (24) is within the above range, warpage of the molded product tends to be effectively reduced.
In this specification, the "pitch of the convex portions" means the center-to-center distance between two adjacent convex portions 14 (24) when the convex portions 14 (24) are viewed from above ( 2 and 4), the pitch b is the average value of pitches measured for five or more convex portions 14 (24).

The height a and the pitch b of the convex portion 14 (24) can be visually measured from an observation image obtained using an optical microscope, an electron microscope, a digital microscope, or the like. It can be measured by the method described in the examples.

The diameter of the convex portion 14 (24) when the main surface 11 (21) having the convex portion 14 (24) is observed from above (that is, when viewed from above in a direction perpendicular to the main surface) is 0. .1 to 600 μm, more preferably 0.5 to 500 μm, still more preferably 1 to 400 μm.
When the shape of the convex portion 14 (24) in plan view is a line pattern (linear), the diameter of the convex portion 14 (24) is the length of the width in the direction perpendicular to the line direction. In other cases, when the planar view shape is a shape other than a circle, it means the diameter of the circumscribed circle. The diameter of the convex portion 14 (24) in plan view can be visually measured from an observation image obtained using an optical microscope, an electron microscope, a digital microscope, or the like.
The size (that is, height and diameter in plan view) of the convex portions 14 (24) may be the same or different for all the convex portions 14 (24).

The overall shape of the molded product 1 (2) of this embodiment has a plurality of fine convex portions 14 (24) on at least one of the two main surfaces 11 (21) and 12 (22). It is not particularly limited as long as it is plate-like or substantially plate-like.
The shape (planar view shape) when the main surface having the fine convex portions 14 (24) is observed from above includes, for example, polygons such as triangles, squares, rectangles, parallelograms, trapezoids, and pentagons, circles, and ellipses. Shapes include a semicircle, a semiellipse, an ellipse (a shape in which both ends of a pair of parallel straight lines are connected by a semicircle), an annular shape, and the like. Polygons may have rounded corners.
Further, when the area of the portion having the minute convex portions 14 (24) of the main surface 11 (21) having the minute convex portions 14 (24) is taken as 100%, the other main surface 12 (22) on the back side The area of the flat portion of is preferably 80% or more, and considering the mounting of the molded product 1 (2) on various products, a part of the other main surface has an uneven portion for connection to the product ( (not shown). The shape of the concavo-convex portion for connection is not particularly limited. For example, a concavo-convex portion for connection having a size of 2 to 10 mm and a height of 2 to 10 mm is provided near the outer periphery of the molded product 1 (2) for fixing to the product. can be attached.
Furthermore, from the viewpoint of mold release during molding, a frame for ejecting ejector pins may be provided on the outer peripheral portion of the molded product 1 (2).

In the present embodiment, the thickness of the molded product 1 (2) is such that the thickness (the distance in the direction perpendicular to the plane portion) between the plane portions excluding the fine convex portions 14 (24) is 1.5 mm or more and less than 6 mm. It is preferably 2 mm or more and less than 5 mm, and still more preferably 2 mm or more and less than 4 mm. The smaller the thickness, the more difficult it is to control the warpage. On the other hand, the greater the thickness, the more advantageous it is in controlling warpage, but it takes longer to cool during molding, creating a temperature difference between the surface and the inside, and the central part is recessed, resulting in poor flatness of the molded product 1 (2). There is a risk that the optical properties of the molded article 1 (2) will be adversely affected. When one main surface 11 (21) does not have a flat portion (a convex portion is arranged on the entire surface of the main surface 11 (21)), the flat portion of the other main surface 12 (22) It may be the average value of the distance in the direction perpendicular to the plane portion to the base of the convex portion 14 (24) of one main surface 11 (21). In addition, when both of the two main surfaces 11 (21) and 12 (22) do not have flat portions (both main surfaces have convex portions arranged entirely), one of the main surfaces 11 (21 ) to the root of the convex portion 14 (24) on the other main surface 12 (22) in the direction perpendicular to the plane portion.
The sizes of the main surfaces 11 (21) and 12 (22) of the molded product 1 (2) are not particularly limited, and may be set according to the purpose.

As shown in FIG. 1, the plate-like molded product 1 (2) of the present embodiment has fine convex portions 14 formed only on one main surface 11, and the other main surface 12 is flat and has uneven portions. In the case of an unformed shape, the amount of warp is preferably 0.4 mm or less, more preferably 0.35 mm or less, and even more preferably 0.3 mm or less. If the amount of warp is 0.4 mm or less, it can be said that the molded product has good dimensional accuracy.
Further, the square root of the area value when the region 13 having the convex portion 14 formed thereon is viewed from above with the main surface 11 having the convex portion 14 formed thereon as the upper surface is calculated (for example, the square root having the dimensions shown in FIG. 1 In this case, since the shaping surface area is 80 mm square, the square root is 80 mm). It is more preferably 0.44% or less, still more preferably 0.38% or less.
In addition, the amount of warp is measured by placing the main surface 11 having the convex portion 14 on the metal platen and measuring the outer circumference of the molded product 1 at four points (for example, points 15a, 15b, 15c, and 15d in FIG. 1). 4 points) are divided so that the length between two adjacent points is equal, and when measuring the size of the gap between the molded product and the surface plate at the four points, the gap is the largest It is a value at a place, and specifically, it can be measured by the method described in Examples described later.

The plate-like molded product 1 (2) of the present embodiment preferably has a filling degree of 0.92 or more, more preferably 0.95 or more, and still more preferably 0.99 or more. When the degree of filling is 0.92 or more, it can be said that the molded product has the convex portion 14 (24) formed satisfactorily.
The degree of filling is calculated by the following formula from the height a of the convex portion 14 (24) and the depth of the concave portion in the mold for shaping the convex portion 14 (24). and the average value at four locations. Specifically, it can be measured by the method described in the examples below.
(Filling degree) = (height a of convex portion of molded product)/(depth of concave portion of mold)

The plate-like molded product of the present embodiment preferably has a birefringence value of 100 nm or less as an in-plane retardation of the main surface 11 (21) having the fine convex portions 14 (24), more preferably It is less than 50 nm, more preferably less than 20 nm. When the in-plane retardation is within the above range, the polarization of light transmitted through the molded product tends to be kept constant, and the optical properties are less likely to be adversely affected. When polarized light passes through the inside of a molded product, the phase difference changes if total reflection occurs inside the molded product. The retardation imparted to the final transmitted light is constant and functions like a retardation plate. Since the polarization characteristics are evenly distributed, projectors, head-up displays, headsets and other optical devices that utilize various types of polarized light, materials for aerial displays, and in-vehicle displays that are expected to be viewed with polarized sunglasses. It works effectively when combined with a video display device such as. When combined with a liquid crystal display, an optical element using liquid crystal, and a polarizing plate, it is useful for improving light utilization efficiency and reducing noise. In addition, when using a circularly polarizing plate or a polarizing plate to cut outside light, or when wearing polarized sunglasses, it works favorably for improving visibility.
The in-plane retardation can be measured by the method described in Examples below.

The plate-shaped molded product of this embodiment contains a methacrylic resin composition having a tensile breaking strain of 1.5% or more and a glass transition temperature (Tg) of 115 to 150°C.

((methacrylic resin composition))
The methacrylic resin composition contained in the plate-shaped molded article of the present embodiment is characterized by containing a methacrylic resin, and may optionally contain additives. A thermoplastic resin other than the resin, a rubbery polymer, and the like may be included.

-Methacrylic resin-
The methacrylic resin contained in the methacrylic resin composition is described below.
The methacrylic resin is not particularly limited, but examples thereof include resins mainly composed of structural units derived from methyl methacrylate, which include homopolymers of methyl methacrylate, or methyl methacrylate and methyl acrylate, Ethyl acrylate, n-propyl acrylate, isopropyl acrylate, butyl acrylate, acrylonitrile, acrylic acid, methacrylic acid, vinylpyridine, vinylmorpholine, vinylpyridonetetrahydrofurfuryl acrylate, N,N-dimethylaminoethyl acrylate, N,N-dimethylacrylamide , 2-hydroxyacrylate, 2-(hydroxymethyl)ethyl acrylate, ethylene glycol monoacrylate, glycerin monoacrylate, maleic anhydride, N-cyclohexylmaleimide, N-phenylmaleimide, styrene, or α-methylstyrene. Copolymers with any one or more of the possible monomers are included. In addition, heat-resistant methacrylic resins having a structural unit derived from methyl methacrylate and a lactone ring or glutarimide in the main chain, methyl methacrylate and low hygroscopic methacrylic resins, and the like are included. These may be used individually by 1 type, and may be used in blend of 2 or more types.

The methacrylic resin is preferably a methacrylic resin having a ring structure in its main chain from the viewpoint of transparency and heat resistance. A methacrylic resin having a structural unit derived from an N-substituted maleimide monomer is particularly preferred because it is easy to control optical properties to a high degree.

- Method for producing methacrylic resin -
A method for producing the methacrylic resin will be described below.
In the method for producing a methacrylic resin, a batch (batch) system, a semi-batch (semi-batch) system, or a continuous system can be used as the polymerization system. Here, the batch system is a process in which the reaction is started and progressed after all raw materials are fed into the reactor, and the product is recovered after completion. In addition, the semi-batch type is a process in which either raw material input or product recovery is performed simultaneously during the progress of the reaction. Furthermore, the continuous system is a process in which both raw material input and product recovery are performed simultaneously while the reaction is in progress. From the viewpoint of precisely controlling the composition of the copolymer, the method for producing the methacrylic resin according to the present embodiment is preferably a semi-batch method in which a part of the raw materials is added after the reaction is started.

Although the continuous method can be used as a method for producing the methacrylic resin contained in the plate-like molding 1 (2) of the present embodiment, it is not preferable for the following reasons. That is, the continuous system has the advantage of being able to reduce the difference in monomer composition between fractions having different molecular weights in the methacrylic resin when the polymerization reaction is carried out in a single complete mixing reactor. Since a large amount of unreacted monomer remains after polymerization, it tends to adversely affect color tone. On the other hand, the continuous type can reduce the amount of unreacted monomer when using a plug flow reactor, but the monomer Compositional differences tend to be large. The amount of unreacted monomer can be reduced even when a plurality of complete mixing reactors or a complete mixing reactor and a plug flow reactor are combined in series, but the difference in monomer composition between the above fractions tends to increase.

The polymerization solvent is not particularly limited, and examples thereof include aromatic hydrocarbons such as toluene, xylene, ethylbenzene, and isopropylbenzene; esters such as methyl isobutyrate; ketones such as methyl isobutyl ketone, butyl cellosolve, methyl ethyl ketone, and cyclohexanone; , 2-methylpyrrolidone and the like can be used.
Alcohols such as methanol, ethanol, and isopropanol may also be used as a polymerization solvent as long as they do not inhibit the dissolution of the polymerization product during polymerization.
The amount of the solvent used during polymerization is not particularly limited as long as the polymerization proceeds, the copolymer and the monomer used do not precipitate during production, and the amount can be easily removed. When the total amount is 100 parts by mass, it is preferably 10 to 200 parts by mass, more preferably 25 to 200 parts by mass, still more preferably 50 to 200 parts by mass, and still more preferably 50 to 150 parts by mass. .

Any initiator generally used in radical polymerization can be used as the polymerization initiator. Examples include cumene hydroperoxide, diisopropylbenzene hydroperoxide, di-t-butyl peroxide, lauroyl peroxide, and benzoyl peroxide. Oxide, organic peroxides such as t-butylperoxyisopropyl carbonate, t-amylperoxy-2-ethylhexanoate, t-amylperoxyisononanoate, 1,1-di(t-butylperoxy)cyclohexane substance; 2,2′-azobis(isobutyronitrile), 1,1′-azobis(cyclohexanecarbonitrile), 2,2′-azobis(2,4-dimethylvaleronitrile), dimethyl-2,2′- azo compounds such as azobisisobutyrate; and the like.
These may be used alone or in combination of two or more.
These polymerization initiators may be added at any stage as long as the polymerization reaction is in progress.
The amount of the polymerization initiator to be added may be 0.01 to 1 part by mass, preferably 0.05 to 0.5 part by mass, when the total amount of monomers used for polymerization is 100 parts by mass.

As the chain transfer agent, a chain transfer agent used in general radical polymerization can be used. mercaptan compounds; halogen compounds such as carbon tetrachloride, methylene chloride and bromoform; unsaturated hydrocarbon compounds such as α-methylstyrene dimer, α-terpinene, dipentene and terpinolene;
These may be used alone or in combination of two or more.
These chain transfer agents may be added at any stage as long as the polymerization reaction is in progress, and are not particularly limited.
The amount of chain transfer agent to be added may be 0.01 to 1 part by mass, preferably 0.05 to 0.5 part by mass, when the total amount of monomers used for polymerization is 100 parts by mass.

The method for recovering the polymer from the polymerization liquid obtained by solution polymerization is not particularly limited. After adding the polymerization liquid in the presence of an excess amount, treatment with a homogenizer (emulsification dispersion) is performed, and unreacted monomers are subjected to pretreatment such as liquid-liquid extraction and solid-liquid extraction. a method of separating from the polymerization solution; or a method of separating the polymerization solvent and unreacted monomers through a step called devolatilization step to recover the polymerization product; and the like.
Here, the devolatilization step refers to a step of removing volatile matter such as a polymerization solvent, residual monomers, and reaction by-products under heating and reduced pressure conditions.

Devices used in the devolatilization process include, for example, a devolatilization device consisting of a tubular heat exchanger and a devolatilization tank; thin film evaporators such as Wyblen and Exeva manufactured by Kobelco Eco-Solutions Co., Ltd., Contra and inclined blade Contra manufactured by Hitachi; A vented extruder with sufficient residence time and surface area to exhibit vaporization performance;
A devolatilization step or the like using a devolatilization device in which two or more of these devices are combined can also be used.

From the viewpoint of improving the color tone, it is preferable to use a devolatilization device which has a heat exchanger and a vacuum vessel as its main structure and does not have a rotating part as its structure.
Specifically, a devolatilization tank having a configuration in which a decompression unit is attached to a decompression vessel having a size that allows devolatilization and a heat exchanger disposed on the top thereof, and a gear pump for discharging the polymer after devolatilization. It is possible to employ a devolatilization device composed of a discharge device such as
The devolatilization device transfers the polymerization solution to a heat exchanger placed in the upper part of the decompression vessel and heated, for example, a shell-and-tube heat exchanger, a plate-fin heat exchanger, a plate-type heat exchanger having a plate-type flow path and a heater. After being preheated in a heat exchanger or the like, the mixture is supplied to a devolatilization tank under heating and reduced pressure to separate and remove the polymerization solvent, unreacted raw material mixture, polymerization by-products, etc., and the copolymer. It is preferable to use a devolatilization device that does not have a rotating part as described above, because a methacrylic resin having a good color tone can be obtained.

The treatment temperature in the devolatilizer is preferably 150 to 350°C, more preferably 170 to 300°C, still more preferably 200 to 280°C. By setting the temperature to the lower limit temperature or higher, residual volatile matter can be suppressed, and by setting the temperature to the upper limit temperature or lower, coloring and decomposition of the obtained acrylic resin can be suppressed.

-Additive-
The methacrylic resin composition contained in the plate-like molded article 1 (2) of the present embodiment may contain various additives within a range that does not significantly impair the effects of the present invention.
Additives are not particularly limited, but include, for example, antioxidants, light stabilizers such as hindered amine light stabilizers, ultraviolet absorbers, release agents, thermoplastic resins other than methacrylic resins, and paraffin-based processes. Oil, naphthenic process oil, aromatic process oil, paraffin, organic polysiloxane, softeners/plasticizers such as mineral oil, flame retardants, antistatic agents, organic fibers, inorganic fillers such as pigments such as iron oxide, Reinforcing agents such as glass fibers, carbon fibers, and metal whiskers, colorants, organic phosphorus compounds such as phosphites, phosphonites, and phosphate esters, or mixtures thereof may be used.

--Antioxidant--
The methacrylic resin composition contained in the plate-like molded article 1 (2) of the present embodiment preferably contains an antioxidant that suppresses deterioration and coloration during molding or during use.
Examples of the antioxidant include, but are not limited to, hindered phenol-based antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, and the like. The methacrylic resin composition of the present embodiment controls the distortion and warpage of the surface of the molded product to a high degree while improving the transferability of the fine convex shape shaping part of the mold. It is important to hold it and provide an appropriate cooling time. When subjected to a long-term heat history, it is necessary to increase the amount of heat stabilizer added in order to obtain the desired heat stability. It is preferable to use a plurality of types of heat stabilizers together, for example, it is preferable to use at least one selected from phosphorus antioxidants and sulfur antioxidants together with a hindered phenol antioxidant.
These antioxidants may be used singly or in combination of two or more.

Hindered phenol antioxidants include, but are not limited to, pentaerythritol tetrakis [3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], thiodiethylene bis [3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 3,3′,3 '',5,5',5''-hexa-tert-butyl-a,a',a''-(mesitylene-2,4,6-triyl)tri-p-cresol, 4,6-bis( octylthiomethyl)-o-cresol, 4,6-bis(dodecylthiomethyl)-o-cresol, ethylenebis(oxyethylene)bis[3-(5-tert-butyl-4-hydroxy-m-tolyl)propionate ], hexamethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl) -1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 1,3,5-tris[(4-tert-butyl-3-hydroxy-2,6-xyline)methyl ]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 2,6-di-tert-butyl-4-(4,6-bis(octylthio)-1,3 ,5-triazin-2-ylamine)phenol, 2-[1-(2-hydroxy-3,5-di-tert-pentylphenyl)ethyl]-4,6-di-tert-pentylphenyl acrylic acid, acrylic acid 2-tert-butyl-4-methyl-6-(2-hydroxy-3-tert-butyl-5-methylbenzyl)phenyl and the like.
In particular pentaerythritol terakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, 2-[1-(2-Hydroxy-3,5-di-tert-pentylphenyl)ethyl]-4,6-di-tert-pentylphenyl acrylate is preferred.

In addition, the hindered phenol-based antioxidant as the antioxidant may be a commercially available phenol-based antioxidant, and such a commercially available phenol-based antioxidant is limited to the following. However, for example, Irganox 1010 (Irganox 1010: pentaerythritol tetrakis [3-(3,5-di-t-butyl-4-hydroxyphenyl) propionate], manufactured by BASF), Irganox 1076 (Irganox 1076: octadecyl -3-(3,5-di-t-butyl-4-hydroxyphenyl) propionate, manufactured by BASF), Irganox 1330 (Irganox 1330: 3,3′,3″,5,5′,5″- Hexa-t-butyl-a,a',a''-(mesitylene-2,4,6-triyl)tri-p-cresol, manufactured by BASF), Irganox 3114 (Irganox3114: 1,3,5-tris (3,5-di-t-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, manufactured by BASF), Irganox 3125 , manufactured by BASF), Adekastab AO-60 (pentaerythritol tetrakis [3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], manufactured by ADEKA), Adekastab AO-80 (3,9- Bis{2-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5. 5] Undecane, manufactured by ADEKA), Sumilizer BHT (Sumilizer BHT, manufactured by Sumitomo Chemical), Cyanox 1790 (Cyanox 1790, manufactured by Cytec), Sumilizer GA-80 (Sumilizer GA-80, manufactured by Sumitomo Chemical), Sumilizer GS (Sumilizer GS: 2-[1-(2-Hydroxy-3,5-di-tert-pentylphenyl)ethyl]-4,6-di-tert-pentylphenyl acrylate, manufactured by Sumitomo Chemical), Sumilizer GM (Sumilizer GM: acrylic acid 2-tert-butyl-4-methyl-6-(2-hydroxy-3-tert-butyl-5-methylbenzyl)phenyl, manufactured by Sumitomo Chemical), vitamin E (manufactured by Eisai), and the like.
Among these commercially available phenolic antioxidants, Irganox 1010, Adekastab AO-60, Adekastab AO-80, Irganox 1076, Sumilizer GS, etc. are preferable from the viewpoint of the effect of imparting thermal stability to the resin.
These may be used individually by 1 type, or may be used in combination of 2 or more types.

Further, the phosphorus-based antioxidant as the antioxidant is not limited to the following, but for example, tris(2,4-di-t-butylphenyl)phosphite, bis(2,4- Bis(1,1-dimethylethyl)-6-methylphenyl)ethyl ester phosphorous acid, tetrakis(2,4-di-t-butylphenyl)(1,1-biphenyl)-4,4'-diylbisphosph Phonite, bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite, bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite, bis(2,4 -dicumylphenyl)pentaerythritol-diphosphite, tetrakis(2,4-t-butylphenyl)(1,1-biphenyl)-4,4'-diylbisphosphonite, di-t-butyl-m-cresyl- Phosphonite, 4-[3-[(2,4,8,10-tetra-tert-butyldibenzo[d,f][1,3,2]dioxaphosphepin)-6-yloxy]propyl]-2 -methyl-6-tert-butylphenol and the like.
Furthermore, a commercially available phosphorus antioxidant may be used as the phosphorus antioxidant, and examples of such commercially available phosphorus antioxidants include, but are not limited to, Irgafos 168 ( Irgafos168: tris (2,4-di-t-butylphenyl) phosphite, manufactured by BASF), Irgafos 12 (Irgafos12: tris [2-[[2,4,8,10-tetra-t-butyldibenzo[d, f][1,3,2]dioxaphosphefin-6-yl]oxy]ethyl]amine, manufactured by BASF), Irgafos 38 (Irgafos 38: bis(2,4-bis(1,1-dimethylethyl) -6-methylphenyl) ethyl ester phosphorous acid, manufactured by BASF), ADEKA STAB 329K (ADK STAB-229K, manufactured by ADEKA), ADEKA STAB PEP-36 (ADK STAB PEP-36, manufactured by ADEKA), ADEKA STAB PEP-36A (ADK STAB PEP-36A, manufactured by ADEKA), ADEKA STAB PEP-8 (ADK STAB PEP-8, manufactured by ADEKA), ADEKA STAB HP-10 (ADK STAB HP-10, manufactured by ADEKA), ADEKA STAB 2112 (ADK STAB 2112, manufactured by ADEKA), ADEKA STAB 1178 (ADKA STAB 1178, made by ADEKA), ADEKA STAB 1500 (ADK STAB 1500, made by ADEKA), Sandstab P-EPQ (made by Clariant), Weston 618 (Weston 618, made by GE), Weston 619G (Weston 619G, made by GE), Ultranox 626 (Ultranox 626, manufactured by GE), Sumilizer GP (Sumilizer GP: 4-[3-[(2,4,8,10-tetra-tert-butyldibenzo[d,f][1,3,2] Dioxaphosphepin)-6-yloxy]propyl]-2-methyl-6-tert-butylphenol, manufactured by Sumitomo Chemical), HCA (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide) , manufactured by Sanko Co., Ltd.) and the like.
Among these commercially available phosphorus-based antioxidants, Irgafos 168, Adekastab PEP-36, Adekastab PEP-36A, and Adekastab HP are considered effective in imparting thermal stability to the resin and in combination with various antioxidants. -10 and Adekastab 1178 are preferred, and Adekastab PEP-36A and Adekastab PEP-36 are particularly preferred.
These phosphorus-based antioxidants may be used alone or in combination of two or more.

Further, the sulfur-based antioxidant as the antioxidant is not limited to the following, but for example, 2,4-bis(dodecylthiomethyl)-6-methylphenol (Irganox 1726, BASF ), 2,4-bis(octylthiomethyl)-6-methylphenol (Irganox 1520L, manufactured by BASF), 2,2-bis{[3-(dodecylthio)-1-oxoporopoxy]methyl}propane-1 ,3-diylbis[3-dodecylthio]propionate] (adekastab AO-412S, manufactured by ADEKA), 2,2-bis{[3-(dodecylthio)-1-oxoporopoxy]methyl}propane-1,3-diylbis[3 -dodecylthio]propionate] (Cheminox PLS, manufactured by Chemipro Kasei Co., Ltd.), di(tridecyl) 3,3′-thiodipropionate (AO-503, manufactured by ADEKA), and the like.
Among these commercially available sulfur antioxidants, Adekastab AO-412S and Cheminox PLS are preferred from the viewpoints of thermal stability imparting effect in the resin, combined effect with various antioxidants, and handleability.
These sulfur-based antioxidants may be used alone or in combination of two or more.

The content of the antioxidant may be any amount as long as the effect of improving the thermal stability is obtained, and if the content is excessive, problems such as bleeding out during processing may occur. Based on 100 parts by mass of the system resin, it is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, still more preferably 1 part by mass or less, even more preferably 0.8 parts by mass or less. It is preferably 0.01 to 0.8 parts by mass, particularly preferably 0.01 to 0.5 parts by mass.

--Ultraviolet absorber--
The methacrylic resin composition contained in the plate-like molded article 1 (2) of this embodiment can contain an ultraviolet absorber.
Although the ultraviolet absorber is not particularly limited, it is preferably an ultraviolet absorber having a maximum absorption wavelength of 280 to 380 nm. Examples include benzotriazole compounds, benzotriazine compounds, benzophenone compounds, and oxybenzophenone compounds. , benzoate-based compounds, phenol-based compounds, oxazole-based compounds, cyanoacrylate-based compounds, benzoxazinone-based compounds, and the like.
These ultraviolet absorbers may be used singly or in combination of two or more.

As the UV absorber, benzotriazole-based compounds and benzotriazine-based compounds having a molecular weight of 400 or more are preferable from the viewpoint of compatibility with resins and volatility when heated. Benzotriazine-based compounds are particularly preferred from the viewpoint of inhibiting decomposition by.

The content of the ultraviolet absorber is not particularly limited as long as it does not impair heat resistance, moist heat resistance, thermal stability, and moldability and exhibits the effects of the present invention, but 100 parts by mass of the methacrylic resin. is preferably 0.1 to 5 parts by mass, preferably 0.2 to 4 parts by mass, more preferably 0.25 to 3 parts by mass, and still more preferably 0.3 to 3 parts by mass. part by mass. Within this range, the balance between ultraviolet absorption performance, moldability, and the like is excellent.

--Release agent--
The methacrylic resin composition contained in the plate-like molded article 1 (2) of the present embodiment can contain a release agent. Examples of the release agent include, but are not limited to, fatty acid esters, fatty acid amides, fatty acid metal salts, hydrocarbon-based lubricants, alcohol-based lubricants, polyalkylene glycols, carboxylic acid esters, carbonized Hydrogen-based paraffinic mineral oils and the like are included.
These release agents may be used singly or in combination of two or more.

Fatty acid esters that can be used as the release agent are not particularly limited, and conventionally known ones can be used.
Examples of fatty acid esters include fatty acids having 12 to 32 carbon atoms such as lauric acid, palmitic acid, heptadecanoic acid, stearic acid, oleic acid, arachidic acid and behenic acid, and monovalent acids such as palmityl alcohol, stearyl alcohol and behenyl alcohol. Ester compounds with fatty alcohols and polyhydric fatty alcohols such as glycerin, pentaerythritol, dipentaerythritol and sorbitan; Complex esters of fatty acids, polybasic organic acids and monohydric fatty alcohols or polyhydric fatty alcohols A compound or the like can be used.
Examples of such fatty acid ester-based lubricants include cetyl palmitate, butyl stearate, stearyl stearate, stearyl citrate, glycerin monocaprylate, glycerin monocaprate, glycerin monolaurate, glycerin monopalmitate, glycerin dipalmi. Tate, Glycerin Monostearate, Glycerin Distearate, Glycerin Tristearate, Glycerin Monooleate, Glycerin Dioleate, Glycerin Trioleate, Glycerin Monolinoleate, Glycerin Monobehenate, Glycerin Mono 12-Hydroxystearate, Glycerin Di-12-hydroxystearate, glycerin tri-12-hydroxystearate, glycerin diacetomonostearate, glycerin citric acid fatty acid ester, pentaerythritol adipate stearate, montanic acid partially saponified ester, pentaerythritol tetrastearate, dipenta Erythritol hexastearate, sorbitan tristearate and the like can be mentioned.
These fatty acid ester-based lubricants can be used singly or in combination of two or more.
Examples of commercially available products include Rikemal series, Poem series, Rikester series, Rikemaster series manufactured by Riken Vitamin Co., Ltd., Excel series manufactured by Kao Corporation, Rheodor series, Exceparl series, Coconard series, and more specific examples. Rikemar S-100, Rikemar H-100, Poem V-100, Rikemar B-100, Rikemar HC-100, Rikemar S-200, Poem B-200, Rikester EW-200, Rikester EW-400, Excel S -95, Rheodol MS-50 and the like.

The content of the release agent may be any amount as long as it is effective as a release agent. If the content is excessive, problems such as bleeding out during processing and extrusion failure due to screw slippage will occur. Therefore, it is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, still more preferably 1 part by mass or less, and still more preferably 0.8 parts by mass with respect to 100 parts by mass of the methacrylic resin. or less, more preferably 0.01 to 0.8 parts by mass, particularly preferably 0.01 to 0.5 parts by mass. When added in an amount within the above range, the decrease in transparency due to the addition of the release agent is suppressed, and there is a tendency to suppress release defects during injection molding.

--other thermoplastics--
The methacrylic resin composition contained in the plate-shaped molded article 1 (2) of the present embodiment does not impair the object of the present invention, and is used for the purpose of adjusting birefringence and improving flexibility. It can also contain a thermoplastic resin.
Other thermoplastic resins include, for example, polyacrylates such as polybutyl acrylate; polystyrene, styrene-methyl methacrylate copolymer, styrene-butyl acrylate copolymer, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene Styrene-based polymers such as block copolymers; etc., acrylic rubber particles having a three- to four-layer structure; JP-B-60-17406, a rubbery polymer disclosed in JP-A-8-245854; , methacrylic rubber-containing graft copolymer particles obtained by multistage polymerization;
Among these, from the viewpoint of obtaining good optical properties and mechanical properties, it is preferable to use a composition compatible with a styrene-acrylonitrile copolymer or a methacrylic resin containing a structural unit (X) having a ring structure in the main chain. A rubber-containing graft copolymer particle having a graft portion on its surface layer is preferred.
The average particle size of the acrylic rubber particles, the methacrylic rubber-containing graft copolymer particles, and the rubbery polymer mentioned above is such that the impact strength, optical properties, etc. of the molded article obtained from the composition of the present embodiment are enhanced. From the point of view, it is preferably 0.03 to 1 μm, more preferably 0.05 to 0.5 μm.

The content of the other thermoplastic resin is preferably 0 to 50 parts by mass, more preferably 0 to 25 parts by mass, based on 100 parts by mass of the methacrylic resin.

The methacrylic resin composition contained in the plate-shaped molding 1 (2) of the present embodiment has a glass transition temperature (Tg) of 115 to 150° C. measured by the midpoint method according to JIS-K7121. When the Tg of the methacrylic resin composition is 115° C. or higher, it is higher than the boiling point of the solvent component for adjusting the general mold release agent used during molding, so the mold temperature is set to the boiling point or higher to adjust the solvent. can volatilize. Moreover, if the molded product does not have heat resistance of 115° C. or higher, warping and deformation of the convex portion 14 (24) occur in reliability tests such as high-temperature aging tests, adversely affecting optical characteristics. On the other hand, if the glass transition temperature (Tg) is higher than 150° C., there are few types of devices that can raise the maximum temperature Tmax of the mold to an appropriate temperature, and it takes time to raise and lower the temperature of the mold, resulting in a long cycle time. I don't like it because it's too long. The glass transition temperature (Tg) is preferably 120-145°C, particularly preferably 125-140°C.
Specifically, the glass transition temperature of the methacrylic resin composition can be measured by the method described in Examples described later.

The methacrylic resin composition used in the present embodiment preferably has a low viscosity corresponding to injection and a high fluidity in order to improve the transferability of fine convex shapes. Therefore, the melt viscosity at 270° C. and 1000 sec ⁻¹ is preferably 20 to 235 Pa·sec, more preferably 20 to 230 Pa·sec, still more preferably 30 to 180 Pa·sec, particularly preferably. is 50 to 150 Pa·sec. If the melt viscosity is less than 20 Pa·sec, it is difficult to control the flow of the resin during injection, and air entrainment tends to deteriorate the transferability of fine convex shapes. When the melt viscosity is higher than 235 Pa·sec, the fluidity of the resin is lowered, and the transferability of the convex shape to the molded product 1 (2) tends to be deteriorated.
The melt viscosity is a value measured in accordance with JIS-K7199, and specifically, it can be measured by the method described in Examples below.

The methacrylic resin composition contained in the plate-like molded product 1 (2) of the present embodiment preferably has a large tensile breaking strain in order to avoid cracking during mold release and resin residue in the mold. The tensile breaking strain is 1.5% or more, preferably 2.0% or more, more preferably 2.5% or more. If the value of the tensile breaking strain of the methacrylic resin composition is within the above range, the molded article can be removed from the mold without causing mold release failure.
The tensile breaking strain is a value measured in accordance with ISO527, and specifically, it can be measured by the method described in Examples described later.

((Method for producing methacrylic resin composition))
As a method for producing the methacrylic resin composition contained in the plate-shaped molded article 1 (2) of the present embodiment, for example, kneading is performed using a kneader such as an extruder, a heating roll, a kneader, a roller mixer, or a Banbury mixer. method. Among them, kneading by an extruder is preferable in terms of productivity.
The kneading temperature may follow the preferred processing temperature of the polymer constituting the methacrylic resin and other resins to be mixed, and is generally in the range of 140 to 300.degree. Also, the extruder is preferably provided with a vent port for the purpose of reducing volatile matter.

(Manufacturing method of plate-shaped molded product)
A method for manufacturing the plate-like molded product of this embodiment will be described below.
The plate-like molded product 1 (2) of the present embodiment is manufactured by injection molding the methacrylic resin composition described above, and can be manufactured using, for example, an injection molding machine. When manufacturing the plate-shaped molded product 1 (2) using an injection molding machine, the temperature setting from the nozzle tip to the center of the cylinder of the injection molding machine is set to the glass transition temperature (Tg) of the methacrylic resin composition to be used. It is preferable to set the temperature to 120 to 180°C higher. As a result, the molten resin sufficiently flows, and molding can be performed in a state in which deterioration due to thermal decomposition of the resin is suppressed. Thermal decomposition of the resin adversely affects color tone, transmittance, and haze, and also generates gas during injection molding. The trapped gas is not discharged, and the mold transfer rate is deteriorated by hindering the filling of the resin. The temperature from the nozzle tip to the center of the cylinder of the injection molding machine is more preferably 130 to 170° C. higher than the glass transition temperature Tg of the methacrylic resin composition used.

In the present embodiment, in order to improve the transferability of the molded product, the mold temperature is heated to the Tg or higher of the methacrylic resin composition before injection filling the methacrylic resin composition into the mold. It is preferably maintained, more preferably (Tg+15)°C to (Tg+40)°C, still more preferably (Tg+20)°C to (Tg+35)°C.

Moreover, in this embodiment, the first mold on the side that forms one main surface having the fine convex portions 14 (24) and the other mold that does not have the fine convex portions 14 (24). When injection molding a molded product having a convex portion 14 (24) on only one main surface using the second mold on the side that forms the main surface of the second mold, when resin is injected into the mold When the maximum temperature of the first mold is Tmax, the temperature of the second mold is preferably between (Tmax-65)°C and (Tmax-50)°C. More preferably (Tmax-65)°C to (Tmax-55)°C, particularly preferably (Tmax-65)°C to (Tmax-60)°C. When the temperature of the second mold is (Tmax-65)° C. or higher, the amount of warpage of the molded product tends to be small. On the other hand, if the temperature is (Tmax−50)° C. or less, the main surface (where the recessed portion 14 (24) is not formed) is the flat surface of the molded product due to the effects of heat shrinkage of the resin and sticking to the mold. Since deterioration of flatness is suppressed, it is possible to obtain a plate-like molded product with good appearance.

Moreover, in the present embodiment, it is preferable to cool the first mold after heating it.
The maximum temperature Tmax of the first mold when heated is preferably controlled in the temperature range of (Tg + 15) ° C. to (Tg + 40) ° C. in order to improve the transferability (moldability) of the fine convex shape. It is preferably (Tg+15)°C to (Tg+35)°C, more preferably (Tg+20)°C to (Tg+35)°C. Even if the temperature is set above (Tg+40)° C., there is no change in the transferability, but there is a tendency to adversely affect the releasability. On the other hand, when the temperature is less than (Tg+15)° C., the transferability tends to deteriorate.
The minimum temperature Tmin of the first mold when cooled is preferably controlled within a temperature range of (Tg-75) ° C. to (Tg-45) ° C., more preferably (Tg-70) ° C. to (Tg -50)°C, more preferably (Tg-65)°C to (Tg-55)°C. Lowering Tmin to temperatures below (Tg-75)° C. increases cycle time. On the other hand, when the temperature exceeds (Tg-45)°C, the amount of warpage of the molded product tends to increase.

In this embodiment, the method of heating the mold is not particularly limited, and any method may be used. For example, a method of arranging a flow path for water and oil in a mold and adjusting the mold temperature above the Tg of the methacrylic resin composition used by media such as water and oil, embedding a heater in the mold, A method of heating the mold, a method of providing an electrically conductive layer on the surface of the mold and generating heat by energizing the mold, a method of heating the mold from outside or inside with an induction heating device, a method of heating the mold from outside or inside the mold, A method of heating by far-infrared radiation from a lamp or a ceramic heater can be used.
In addition, in the method for manufacturing the plate-like molded product 1 (2) of the present embodiment, the method for cooling the mold is not particularly limited, and any method may be used. For example, there is a method of arranging a flow path for water or oil in a mold and cooling with a medium such as water or oil.

In the method for manufacturing the plate-shaped molded product 1 (2) of the present embodiment, the rate of temperature increase of the surface temperature during heating is , preferably 1 to 10° C./second, more preferably 1.5 to 10° C./second, still more preferably 2 to 10° C./second. A faster temperature rise rate is more effective in shortening the cycle time, but as long as there are no restrictions on the cycle time and deterioration of the resin due to heat retention in the cylinder is not a problem, the temperature may be outside this range. The cooling rate of the surface temperature of the mold during cooling is preferably 0.5 to 10°C/sec, more preferably 1 to 10°C/sec, and still more preferably 2 to 10°C/sec. . A faster cooling rate is more effective for shortening the cycle time, but as will be described later, it is more effective to maintain the mold temperature in a high temperature state for improving transferability. However, if the temperature drop rate is out of this range, it tends to lead to redundant cycle time and deterioration of warpage of the molded product, which is not preferable.
In the method for manufacturing the plate-shaped molded product 1 (2) of the present embodiment, the temperature control includes raising and lowering the temperature at a constant rate, slowing down the rate of raising and lowering the temperature, or holding the temperature at a predetermined temperature for a certain period of time. It can be appropriately set while observing the state of the molded product. In order to improve the transfer of the convex shape, it is preferable to keep the holding time at the temperature at which the resin flows (preferably the glass transition temperature or higher) for a long time. In addition, if the holding time is short, birefringence develops due to the formation of a skin layer. From the viewpoint of suppressing this, it is preferable to slow down the cooling rate.

In the method for manufacturing the plate-like molded product 1 (2) of the present embodiment, a mold release coating or a mold release agent is preferably used as the mold release processing on the mold surface. As the release coating, baking-type fluororesin, silicone resin, or the like can be used. In addition, as the coating-type release agent, for example, a fluorine-based, silicone-based, or wax-based release agent can be used.
In particular, for spray-type external release agents that are used by spraying them onto the mold, for example, fluorine-based release agents that form a monomolecular film that has excellent mold release properties and does not easily affect the transfer of the fine shape of the mold. can be used. It is preferable to use a non-curing mold release agent because of its low residual property on the mold.
Further, among the solvent components of the release agent, the highly volatile solvent component containing the active ingredient is mainly composed of a solvent component that hardly dissolves the methacrylic resin composition to be injected and filled into the mold, and the solvent By using a component whose boiling point is lower than or close to the Tg of the methacrylic resin composition, the solvent component hardly remains in the concave portion of the mold that forms the convex shape, and a good release coating is formed. be able to. As the solvent component of the release agent, it is preferable to use one having a low boiling point. Specifically, the boiling point of the solvent component is preferably in the range of (Tg-50)° C. to (Tg+5)° C., more preferably (Tg-40), where Tg is the glass transition temperature of the methacrylic resin composition. °C to (Tg+5) °C, more preferably (Tg-30) °C to (Tg+5) °C. By using a release agent containing a solvent component having a boiling point within this range, it becomes possible to efficiently form a release film, and it is possible to suppress the occurrence of defective release of molded products. Furthermore, since the transfer of the release agent to the surface of the molded article is reduced, the transmittance of the molded article is improved, making it easier to obtain a molded article having both good optical properties and appearance.

The present invention will be described below with reference to specific examples and comparative examples, but the present invention is not limited to these.

[material]
Raw materials used in Examples and Comparative Examples to be described later are shown below.

[[Monomer constituting methacrylic resin]]
・Methyl methacrylate (MMA): manufactured by Asahi Kasei Corporation ・N-Phenylmaleimide (PMI): manufactured by Nippon Shokubai Co., Ltd. ・N-Cyclohexylmaleimide (CMI): manufactured by Nippon Shokubai Co., Ltd. ・Styrene: Fujifilm Wako Pure Chemical Industries, Ltd. Company-manufactured 2-(hydroxymethyl)methyl acrylate (MHMA): Combi-Blocks Co., Ltd.

[[Organic solvent]]
・Meta-xylene (mXy): manufactured by Mitsubishi Gas Chemical Co., Ltd. ・Methyl isobutyrate: manufactured by Kanto Chemical Co., Ltd. ・Toluene: manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.

[[polymerization initiator]]
・ 1,1-di (t-butylperoxy) cyclohexane: manufactured by NOF Corporation ・ t-amylperoxy-2-ethylhexanoate: manufactured by Arkema Yoshitomi Co., Ltd. “Luperox 575”
・ t-amyl peroxyisononanoate: manufactured by Arkema Yoshitomi Co., Ltd.

[[chain transfer agent]]
・n-octyl mercaptan: manufactured by Chevron Phillips Chemical ・n-dodecyl mercaptan: manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.

[[Additive]]
・ Pentaerythritol tetrakis [3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate]: BASF "Irganox 1010"
・ Tris (2,4-di-t-butylphenyl) phosphite: "Irgafos168" manufactured by BASF
Rikemar H-100: manufactured by Riken Vitamin Co., Ltd. Adekastab 2112: manufactured by ADEKA Co., Ltd. Stearyl phosphate / distearyl phosphate mixture: manufactured by Sakai Chemical Industry Co., Ltd. Monomethylamine: manufactured by Mitsubishi Gas Chemical Co., Ltd. Dimethyl carbonate: Fuji Film Wako Pure Chemical Co., Ltd. Triethylamine: Fuji Film Wako Pure Chemical Co., Ltd.

(Characteristic evaluation of methacrylic resin and methacrylic resin composition)
Methods for measuring the properties of the methacrylic resin composition are described below.

(1) Measurement of glass transition temperature The glass transition temperature of the methacrylic resin composition was measured according to JIS-K7121.
Using a differential scanning calorimeter (DSC8000, manufactured by Perkin Lumer Japan Co., Ltd.) under the condition of a nitrogen gas flow rate of 25 mL / min, here, the temperature is raised from room temperature (23 ° C.) to 200 ° C. at 10 ° C. / min (primary The temperature was raised), held at 200°C for 5 minutes to completely melt the sample, then the temperature was lowered from 200°C to 40°C at 10°C/min, held at 40°C for 5 minutes, and further under the above temperature raising conditions. Of the DSC curves drawn while the temperature is raised again (secondary temperature rise), the intersection of the stepwise change partial curve at the time of the second temperature rise and the straight line equidistant from each baseline extension line in the vertical axis direction ( The midpoint glass transition temperature) was measured as the glass transition temperature (Tg) (°C).

(2) Melt viscosity measurement Under conditions conforming to JIS-K7199, a twin capillary rheometer (manufactured by ROSAND) was used to measure the methacrylic resin composition at a temperature of 270°C, a shear rate of 1000 sec ^-1 , and a capillary die diameter of 1 mm. The melt viscosity (Pa·sec) of the product was measured.

(3) Measurement of tensile fracture strain The pellets of the methacrylic resin composition are dried at 80 to 100 ° C. for 24 hours, and are injected using an injection molding machine (manufactured by Toshiba Machine Co., Ltd., EX-100SX) according to JIS-K6717. By molding, a 4.0 mm thick ISO 3167 type A dumbbell specimen was produced. This test piece was subjected to a tensile test according to ISO527 using a low-load universal testing machine (manufactured by Inslon) at a measurement temperature of 23° C. and a crosshead speed of 5 mm/min. The measurement was performed 5 times, the elongation between chucks at tensile breakage was measured, and the average value was calculated as the tensile breakage strain (%). The tensile breaking strain is synonymous with tensile breaking elongation and tensile breaking strain.

(Method for measuring and evaluating molded products)
Measurement and evaluation methods for plate-shaped molded products are described below.

(1) Measurement of height and pitch of convex portion of molded product 1000). The height and pitch of the convex portions formed on the main surface of the molded article were measured from the obtained observation image, and the average values of the five convex portions are shown in Table 1 as the height a and the pitch b, respectively.

(2) Measuring the degree of filling of the convex portion of the molded product A cross section obtained by cutting the plate-shaped molded product in the direction perpendicular to the main surface (thickness direction) with a digital microscope (manufactured by Keyence Corporation, VHX-1000) was observed using The height a of the convex portion formed on the main surface of the molded product is obtained, and the filling degree defined as the ratio to the depth of the concave portion in the mold for shaping the convex shape by the following formula was derived, and the average value of the four points was described in Table 1 as the value of the degree of filling.
Substantially, if the degree of filling is 0.92 or more, it can be determined that the molded product having the convex shape transferred is preferable.
(Filling degree) = (height a of convex portion of molded product)/(depth of concave portion of mold)

(3) Measurement of warp amount of molded product A plate-shaped molded product is placed on a metal surface plate with the main surface having a convex portion as the upper surface, and the outer periphery of the molded product is measured at four points (point 15a in FIG. 1 (A), Four points (points 15b, 15c, and 15d) are divided so that the length between two adjacent points is equal, and the size of the gap created between the molded product and the surface plate at these four points is the thickness. It was measured with a gauge, and the value at the place where the clearance (amount of warp) was the largest was defined as the amount of warp (mm) of the molded product.
In addition, in the case of a molded product having an uneven portion for connection with another part on the back side (the other main surface) of the main surface having the above-mentioned convex shape portion of the molded product, the portion that does not include the uneven portion for connection After trimming so that only a chisel remains, and polishing the cross section with sandpaper, the amount of warpage is measured.
Substantially, in the plate-like molded products 1 and 2 having the shapes shown in FIGS. 1 and 3, if the amount of warp is 0.4 mm or less, it can be judged that the dimensional accuracy of the molded product is within a preferable range.

(4) Evaluation of the appearance of the molded product The plate-shaped molded product was visually observed, and the main surface with the convex portion due to insufficient resin filling on the fine convex shaping surface of the mold on the main surface side having the convex portion. Observation was made for uneven gloss on the surface and poor appearance due to undulations on the back surface of the main surface having the convex portion (the other flat main surface).
If there is a defective resin filling portion, it can be confirmed as if it is partially chipped. The undulations on the other main surface can be determined by, for example, confirming whether or not straight lines are distorted when a reflected image is observed when a fluorescent lamp housed in a rectangular case with a long side is illuminated from above. can judge whether it is good or bad.
"○ (good)" when neither gloss unevenness on the main surface having the convex portion nor undulation on the other main surface was confirmed, and gloss unevenness on the main surface having the convex portion and undulation on the other main surface A case where at least one of the above was confirmed was evaluated as "x (defective)".

(5) Measurement of in-plane retardation of molded product A plate-shaped molded product is placed on a measuring table of PA-300-L (manufactured by Photonic Lattice) in a petri dish. I placed it so that it was on top. Then, a low-viscosity liquid (contact liquid manufactured by Shimadzu Corporation) that has a refractive index close to that of the methacrylic resin used and does not attack the methacrylic resin is applied to the top of the convex portion of the molded product. The petri dish was filled so that the main surface of the molded article having the convex portion was immersed in the liquid so that the surface of the liquid was flat without height difference. In this state, the in-plane retardation distribution was measured at a wavelength of 520 nm. The average value of the absolute values of the in-plane retardation (Re) in the area where the convex portion is formed (see FIGS. 1A and 3A) was obtained and used as the measured value of the retardation (nm). .
As for the birefringence value, the in-plane retardation is preferably less than 100 nm in order to prevent the optical properties from being adversely affected.

Synthesis Example 1 [Methacrylic resin composition A]
Methyl methacrylate (hereinafter referred to as MMA) 318.7 kg, N-phenylmaleimide (hereinafter referred to as PMI) 35.5 g, N-cyclohexylmaleimide (hereinafter referred to as CMI) 63.7 kg, chain transfer agent n - Weigh 0.341 kg of octyl mercaptan and 225.1 kg of meta-xylene (hereinafter referred to as mXy), add to a 1.25 m ³ reactor equipped with a jacket temperature control device and stirring blades, and stir to obtain a mixed monomer. A solution was obtained.
116.9 kg of mXy was then weighed into tank 1 to prepare the additive solvent.
Further, 104.5 kg of MMA and 85.5 kg of mXy were weighed into tank 2 and stirred to obtain an additional MMA solution.
The contents of the reactor are bubbled with nitrogen at a rate of 30 L/min for 1 hour, and each of tanks 1 and 2 is bubbled with nitrogen at a rate of 10 L/min for 30 minutes to remove dissolved oxygen. bottom.
Thereafter, steam was blown into the jacket to raise the temperature of the solution in the reactor to 125°C, and while stirring at 50 rpm, 0.457 kg of 1,1-di(t-butylperoxy)cyclohexane was dissolved in 2.67 kg of mXy. Polymerization was initiated by adding the resulting polymerization initiator solution at a rate of 1 kg/hour. During the polymerization, the temperature of the solution in the reactor was controlled at 125±2° C. by adjusting the temperature with a jacket. Thirty minutes after the initiation of polymerization, the addition rate of the polymerization initiator solution was reduced to 0.25 kg/hour, and mXy was added from tank 1 at 29.24 kg/hour for 3.5 hours.
Then, 4 hours after the initiation of the polymerization, the addition rate of the polymerization initiator solution was increased to 0.75 kg/hour, and the additional MMA solution was added from tank 2 at 95 kg/hour for 2 hours.
Further, the addition rate of the polymerization initiator solution was reduced to 0.25 kg/hour after 6 hours from the initiation of polymerization, and the addition was stopped after 7 hours from the initiation of polymerization.
After 8 hours from the initiation of polymerization, a polymerization solution containing a methacrylic resin was obtained. To this were added 0.261 kg of Irganox 1010 and 0.784 kg of Irgafos 168 as antioxidants, and 0.784 kg of Rikemal H-100 as a release agent.
Next, the obtained polymerization solution was devolatilized by supplying it to a concentrating device consisting of a tubular heat exchanger preheated to 250° C. and a vaporization tank. The degree of vacuum in the vaporization tank was set to 10 to 15 Torr. The resin flowing down the vaporization tank was discharged with a screw pump, extruded from a strand die, cooled with water, and pelletized to obtain a methacrylic resin composition A having an N-substituted maleimide structural unit.
The obtained pellets had a Tg of 133° C., a melt viscosity of 131 Pa·sec, and a tensile breaking strain of 1.7%.

Synthesis Example 2 [Methacrylic resin composition B]
A monomer composition consisting of 60.000 mol% of methyl methacrylate, 39.998 mol% of styrene, and 0.002 mol% of t-amylperoxy-2-ethylhexanoate as a polymerization initiator was added to a 10-liter complete reactor with helical ribbon blades. Continuous polymerization was carried out at a polymerization temperature of 150° C. for an average residence time of 2.5 hours by continuously supplying the mixture to the mixing tank at a rate of 1 kg/h. The liquid was continuously withdrawn from the bottom of the polymerization vessel so that the liquid level was constant, and supplied to a concentrator comprising a tubular heat exchanger and a vaporization vessel for devolatilization. The degree of vacuum in the vaporization tank was set to 10 to 15 Torr. The resin flowing down the vaporization tank was discharged with a screw pump, extruded through a strand die, cooled with water, pelletized, and introduced into a solvent removal apparatus to obtain a methyl methacrylate-styrene copolymer in the form of pellets.
This copolymer was dissolved in methyl isobutyrate to prepare a 10% by mass methyl isobutyrate solution. A 1000 mL autoclave apparatus was charged with 500 parts by mass of a 10% by mass methyl isobutyrate solution of this copolymer and 1 part by mass of 10% by mass Pd/C (manufactured by NE Chemcat) as a hydrogenation catalyst, hydrogen pressure 9 MPa, 200 ° C. for 15 hours to hydrogenate the aromatic double bond of the styrene portion of the copolymer. After removing the hydrogenation catalyst with a filter and adding and mixing 0.05 parts by mass of Rikemar H-100 to the polymer solution, the mixture is supplied to a concentrator consisting of a tubular heat exchanger and a vaporization tank for devolatilization. went. The degree of vacuum in the vaporization tank was set to 10 to 15 Torr. The resin flowing down the vaporization tank was discharged by a gear pump, extruded from a strand die, cooled with water and pelletized to obtain a methacrylic resin composition B.
The obtained pellets had a Tg of 118° C., a melt viscosity of 67 Pa·sec, and a tensile breaking strain of 2.2%.

Synthesis Example 3 [Methacrylic resin composition C]
5.0 kg of methyl methacrylate, 1.25 kg of 2-(hydroxymethyl)methyl acrylate and chain transfer were placed in a 30 L reactor equipped with a paddle-equipped stirrer, temperature sensor, cooling pipe and nitrogen inlet pipe. As agents, 0.025 parts by mass of n-dodecyl mercaptan, 0.025 parts by mass of Adekastab 2112, and 6.25 kg of toluene per 100 parts by mass of the total amount of all monomers were charged, and the mixture was stirred while passing nitrogen. The temperature was raised to 105° C. while
While refluxing, 0.05 part by mass of t-amyl peroxy isononanoate was added to the polymerization tank with respect to 100 parts by mass of the total amount of all monomers, and 0.1 part by mass of t-amyl peroxy isononanoate was added. was added dropwise over 2 hours, polymerization was carried out under reflux at a polymerization temperature of 105 to 110° C., and the polymerization reaction was further carried out for 6 hours.
6.3 g of a stearyl phosphate/distearyl phosphate mixture was added to the obtained polymer solution, and a cyclization condensation reaction was carried out at 90 to 110° C. for 5 hours. After that, 0.10 parts by mass of Rikemal H-100 was added to 100 parts by mass of the total amount of all monomers, and mixed by stirring.
Using a φ42 mm devolatilizing extruder with 4 front vents and 1 back vent, the obtained polymer solution was subjected to a cyclization condensation reaction and devolatilization treatment at 120 rpm and 2.2 kg / hour in terms of resin amount to obtain a methacrylic resin composition. A pellet of product C was obtained.
The obtained pellets had a Tg of 133° C., a melt viscosity of 165 Pa·sec, and a tensile breaking strain of 3.2%.

Synthesis Example 4 [Methacrylic Resin Composition D]
A methacrylic resin composition having a glutarimide structure was obtained by imidizing polymethyl methacrylate with monomethylamine using a co-rotating twin-screw extruder.
Using a co-rotating twin-screw extruder with a screw diameter of 40 mm, the extruder cylinder temperature is 275 ° C., the screw rotation speed is 150 rpm, and Rikemal H-100 is added from the hopper when the total polymer mass is 100 parts by mass. Polymethyl methacrylate containing 1 part by mass and having a weight average molecular weight of 10,8000 was supplied at 20 kg/hour, and nitrogen was flowed into the extruder at a flow rate of 200 mL/min. After the resin was melted and filled in the kneading block, 1.8 parts by mass of monomethylamine was injected from the nozzle with respect to 100 parts by mass of the raw material resin to carry out an imidization reaction. A reverse flight was placed at the end of the reaction zone (before the vent port) to fill the resin. By-products and excess monomethylamine after the reaction were removed by reducing the pressure at the vent port to 50 Torr. The resin coming out as a strand from the die provided at the exit of the extruder was cooled in a water tank and then pelletized by a pelletizer to obtain an imide resin.
Next, using a co-rotating twin-screw extruder with a screw diameter of 40 mm, the extruder cylinder temperature was set to 255 ° C., the screw rotation speed was set to 150 rpm, the obtained imide resin was supplied at 20 kg / hr, and the kneading block After the resin was melted and filled, a mixed solution of dimethyl carbonate and triethylamine was injected from the nozzle as an esterification agent to reduce the carboxylic acid groups in the resin. Dimethyl carbonate was 3.2 parts by mass and triethylamine was 0.8 parts by mass with respect to 100 parts by mass of the imide resin. By-products and excess dimethyl carbonate after the reaction were removed by reducing the pressure at the vent port to 50 Torr. The resin that came out as a strand from the die provided at the outlet of the extruder was cooled in a water tank and then pelletized by a pelletizer to obtain a methacrylic resin composition D having a glutarimide structure.
The obtained pellets had a Tg of 122° C., a melt viscosity of 158 Pa·sec, and a tensile breaking strain of 7.9%.

Synthesis Example 5 [Methacrylic resin composition E]
Polymerization was carried out in the same manner as in Synthesis Example 1, except that the amount of n-octylmercaptan as a chain transfer agent was changed to 0.708 kg, to obtain a methacrylic resin composition E.
The obtained pellets had a Tg of 134° C., a melt viscosity of 102 Pa·sec, and a tensile breaking strain of 1.2%.

(Example 1)
- Molding of a plate-shaped molded article having a convex portion on one main surface Using the methacrylic resin composition A obtained in Synthesis Example 1, with an injection molding machine (manufactured by Sumitomo Heavy Industries, Ltd., SE180EV-A) Injection molding was performed. The mold has a main surface that is flat with the mold (first mold) on the side that forms the main surface having triangular pyramidal convex portions with a convex portion height of a = 400 μm and a pitch of b = 300 μm. It was attached to an injection molding machine using a telescopic mold in which a heater wire was embedded in the mold near the surface forming each main surface (second mold). The mold temperature of the first mold was heated to the maximum temperature Tmax shown in Table 1 by heating with a heater at a heating rate of about 3° C./sec, and the mold was closed to carry out injection molding. After filling the resin into the mold, the mold temperature of the first mold is cooled to the lowest temperature Tmin listed in Table 1 at a temperature decrease rate of about 1.2 ° C./sec, and after reaching Tmin, the mold is cooled for 30 seconds. After cooling, a plate-like molded product (90 mm long, 90 mm wide, 2.5 mm thick, see FIG. 1) having a convex portion on one main surface was obtained. In addition, the holding pressure is set as high as 80 MPa at the first stage immediately after injection in order to obtain good transfer. It was set to 30 MPa. Table 1 shows the evaluation results.
As is clear from Table 1, in Example 1, the degree of filling was 0.98, and very excellent results were obtained. In addition, the warp and appearance were good.

(Example 2)
・Molding a plate-shaped molded article having a convex portion on one main surface Using the methacrylic resin composition B obtained in Synthesis Example 2, setting the mold temperature Tmax of the first mold to 155 ° C. Molding was performed under the same conditions as in Example 1, except that injection was performed. Table 1 shows the evaluation results.

(Example 3)
- Molding of a plate-like molded product having a convex portion on one principal surface Molding was performed under the same conditions as in Example 2, except that the thermoplastic resin composition C obtained in Synthesis Example 3 was used. Table 1 shows the evaluation results.

(Example 4)
- Molding of a plate-shaped molding having a convex portion on one main surface Molding was performed under the same conditions as in Example 2, except that the thermoplastic resin composition D obtained in Synthesis Example 4 was used. Table 1 shows the evaluation results.

(Example 5)
・Molding a plate-shaped molded article having a convex part on one main surface. 85 degrees), and the other main surface is a flat plate-shaped molded product (length 90 mm, width 90 mm, thickness 2.4 mm, see Fig. 3) Molding was carried out under the same conditions as in Example 1, except that nested molds were used in which heater wires were embedded in the molds near the surfaces forming the main surfaces. Table 1 shows the evaluation results.

(Example 6)
・Molding a plate-shaped molded article having a convex portion on one main surface. A square pyramid with a convex portion height a = 400 μm and a pitch b = 160 μm on one side main surface (bottom is 140 μm square, bottom and side) 85 degrees), and the other main surface is a flat plate-shaped molded product (length 90 mm, width 90 mm, thickness 2.4 mm, see Fig. 3) Molding was carried out under the same conditions as in Example 1, except that nested molds were used in which heater wires were embedded in the molds near the surfaces forming the main surfaces. Table 1 shows the evaluation results.

(Comparative example 1)
The mold has a triangular pyramidal convex portion with a convex portion height a = 700 μm and a pitch b = 300 μm on one main surface, and the other main surface is a flat plate-shaped molded product (length 90 mm , width 90 mm, thickness 2.4 mm), and the same conditions as in Example 1 except that a telescopic mold in which a heater wire is embedded in the mold near the surface forming each main surface was used. molded. In Comparative Example 1, mold release failure occurred in which part of the fine shape remained inside the mold at the time of mold release, so measurement was performed using a location where the molded product could be evaluated. Table 1 shows the evaluation results.

(Comparative example 2)
Molding was performed under the same conditions as in Example 2, except that the methacrylic resin composition E (tensile breaking strain: 1.2%) obtained in Synthesis Example 5 was used. When the molded product was ejected from the mold with an ejector pin and released from the mold, it stuck strongly and a popping sound was generated. A plurality of chips were confirmed at the top of the convex portion of the molded product, and when the first mold was observed, it was confirmed that there was resin residue in the shaping portion (concave portion) of the first mold. Table 1 shows the evaluation results of the good portions of the molded product obtained.
As a result of the evaluation, defects such as uneven gloss on the main surface having convex portions, waviness on the flat main surface, and warping of the molded product were confirmed.

(Comparative Example 3)
Molding was performed under the same conditions as in Example 5, except that the methacrylic resin composition E obtained in Synthesis Example 5 was used. Table 1 shows the evaluation results. In Comparative Example 3, the molded product cracked when released from the mold and the resin remained inside the mold, making it impossible to obtain a non-defective product.

(Comparative Example 4)
Molding was performed under the same conditions as in Example 6, except that the methacrylic resin composition E obtained in Synthesis Example 5 was used. Table 1 shows the evaluation results. In Comparative Example 4, the molded product cracked when released from the mold and the resin remained inside the mold, making it impossible to obtain a non-defective product.

The characteristics of the plate-like moldings having fine convex portions obtained in Example 1 and Comparative Example 1 were evaluated when they were used as light direction changing elements.
As shown in FIG. 5, the incident light enters at an incident angle of 45 degrees with respect to the incident surface (main surface behind the principal surface having the minute convex portions) 81 of the plate-shaped molding 8 having the minute convex portions. The light is reflected by a slope 83 forming an angle of 85 degrees with the bottom surface 82, then refracted from a slope 84 forming an angle of 65 degrees with the bottom surface 82, and emitted to the outside. At this time, since the light is emitted from the slope 84 at a refraction angle of 64 degrees, the light is emitted at an angle of about 90 degrees with respect to the incident surface 81 . In other words, it can be rephrased as a light direction changing element that bends light incident on the incident surface at an incident angle of 45 degrees in a direction perpendicular to the incident surface.
The molded product 8 was arranged in the arrangement shown in FIG. 6, and the clarity of the reflected transmission image was evaluated as a light direction changing element. An LED light source 5 with a collimating lens that emits light of 530 nm (Thorlabs, M530L4) and a frosted diffusion plate 6 (Sigma Koki, #240) are arranged, and USAF Target 7 (Edmund, USAF1951 target negative, target area is about 12 mm) was irradiated from the back. The light of the Target image formed by the light passing through the transmission region 71 (see FIG. 7) of the Target is incident from the incident surface 81 of the molded product 8 at an incident angle of 45°, and is projected onto the convex shaped surface of the molded product 6. (For the light emitted from (the main surface having the minute convex shape portion), a reflected image (an image formed by the light transmitted through the inclined surface 84 after being reflected by the inclined surface 83) is projected in a direction perpendicular to the incident surface 81. The image was taken with a single-lens reflex camera 9 (E-PL5, manufactured by Olympus Co.) placed at a position separated by 350 mm.
The reflected image observed when using the molded article obtained in Example 1 was a clear image, but the reflected image observed when using the molded article obtained in Comparative Example 1 was , distortion and lack of the Target image were confirmed, and the definition was low.

Since the plate-shaped molded article of the present invention has a good appearance, it can be suitably used as various optical members such as members for aerial displays, Fresnel lenses, lenticular lenses, light guide plates, antireflection sheets, anti-glare sheets, and cell culture sheets. can be done.

1, 2: Plate-shaped molded article 11, 21: One main surface (main surface having a fine convex portion)
12, 22: the other main surface (a main surface that may or may not have fine convex portions)
13, 23: Regions where fine convex portions are formed 14, 24: Convex portions 15a, 15b, 15c, 15d: Warp amount measurement points 5: LED light source 6: Frosted diffusion plate 7: USAF Target
71: Transmissive area 72: Light shielding area 8: Plate-shaped molding 81: Incidence surface 82: Bottom surface 83, 84: Inclined surface 9: Single-lens reflex camera

Claims (5)

A plate-shaped molded article having a plurality of fine convex portions with a height a of 50 to 600 μm on at least one main surface, a tensile fracture strain of 1.5% or more, and a glass transition temperature (Tg). A plate-like molded product, characterized by being obtained by injection molding a methacrylic resin composition having a temperature of 115 to 150°C. The ratio b/a of the pitch b of the fine convex portions to the height a of the fine convex portions is 0.1 to 1.0 on the main surface having the fine convex portions. 2. The plate-shaped molded article according to 1. 3. The plate-like molded article according to claim 1, wherein the in-plane retardation of the main surface having the fine convex portions is 100 nm or less. 3. The methacrylic resin composition according to claim 1 or 2, obtained by heating the surface temperature of the mold to a glass transition temperature (Tg) or higher of the methacrylic resin composition and then injection-filling the methacrylic resin composition into the mold. Plate-shaped molded article described. 3. The plate-like molded article according to claim 1, which is a member for an aerial display.

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