JPH08300806A - Inkjet recording sheet - Google Patents

Abstract

(57) [Abstract] [Purpose] An inkjet recording device that prevents damage to the inkjet recording sheet surface caused by contact between the surface of the inkjet recording sheet and a paper feed roll or device installed in the transport section of the printer, and also ensures ink absorption. Get a recording sheet. [Structure] An inkjet recording sheet having a 75-degree surface gloss of 20% or more as measured according to JIS Z8741, which has a support coated with at least one ink-receiving layer, and the support is made of wood. An ink jet recording sheet comprising a composition containing pulp as a main component, and an anchor layer comprising a pigment having a self-adhesive ability is provided between the support and the ink receiving layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording sheet for recording by using an aqueous ink, and particularly, a contact between a paper feed roll or a device installed in a conveyance section of a printer and the surface of the ink jet recording sheet. The present invention relates to an inkjet recording sheet in which the surface of the inkjet recording sheet is prevented from being damaged and the ink absorbency is secured.

[0002]

2. Description of the Related Art The ink jet recording method is a method of ejecting minute droplets of ink by various operating principles and adhering them to an ink jet recording sheet such as paper to record images and characters, but at high speed and low speed. It has features such as noise, easy multi-coloring, great flexibility in recording patterns, and no need for development-fixing. It has rapidly spread in various applications as a recording device for various figures and color images including Chinese characters. ing. Further, an image formed by the multicolor ink jet system can obtain a recording comparable to that of the multicolor printing by the plate making system or the printing by the color photographic system. Further, in applications requiring a small number of copies, it is being widely applied to the full-color image recording field because it is cheaper than the photographic technique.

Examples of the ink jet recording sheet applied to the ink jet recording system include high-quality paper and coated paper used for lithographic printing, letterpress printing, gravure printing and the like. From the aspect, a method of obtaining a good image quality has been studied.
However, due to the speeding up of inkjet recording, the required high quality of images, the expansion of applications, etc., in order to satisfy these requirements, it is becoming difficult only to meet the requirements of the recording apparatus and the ink composition. .

The following items are given as examples of the properties required of the ink jet recording sheet. 1.
Ink absorption is fast. When the ink absorbency is lowered, the ink is diffused to areas other than the printed portion, the sharpness is lowered due to the enlarged dot diameter, and the white paper portion is contaminated by the ink called scumming. Further, this phenomenon becomes remarkable in the portion where the inks overlap. 2. Print dots do not spread. Although the dot diameter depends on the recording apparatus, when the ink lands on the inkjet recording sheet and then diffuses, the color and sharpness deteriorate, resulting in a blurred image. 3. No change in image quality over time. It is not affected by the environment in which it is used. For example, it has excellent light resistance, water resistance, and ozone resistance.

In response to such demands, some proposals have heretofore been made. In order to improve the ink absorbency and prevent the diffusion of print dots, a method of providing an ink absorbing layer on a support (Japanese Patent Laid-Open Nos. 52-9074 and 58-72495, etc.), ink in the ink absorbing layer Paying attention to the fact that the distribution state of the dye component of
A method using a specific agent that adsorbs a dye component (JP-A-55-1)
No. 44172). Further, in order to improve light resistance, water resistance, and ozone resistance, a basic oligomer should be contained (JP-A-60-11389), and a polyvinylamine copolymer should be added to the coating layer in or on the substrate. It is disclosed that a polymer is used (JP-A-64-8085).

Further, in recent years, in order to improve image quality and print speed, conveyance accuracy in a printing process has become an important characteristic. This is because if the transport accuracy is low,
This is because the ink landing position on the paper becomes unstable and the image quality is degraded. When the portion that ejects ink (ink head) scans and prints in the width direction of the paper, the ejection timing may be controlled by an electrical signal, but in addition to the paper feed direction, It is necessary to keep the paper feed accuracy. For this,
The inkjet recording sheet needs to be properly suppressed in the transport section of the recording apparatus, and the inkjet recording sheet, the paper feed roll, and the transport device must be brought into contact with each other under a load. This indicates that the surface of the paper is damaged by the force applied from the paper feed roll or the conveyance device, and if the print surface is damaged, the quality of the image is deteriorated.

In order to avoid damage to the surface, it is possible to harden the surface, but since it is difficult to be crushed in the flattening process, the contact area with the paper feed roll and the transport device is reduced, and the paper feed accuracy is reduced. To do. Increasing the planarization process to increase the contact area will reduce ink absorption.

Although the ink jet recording apparatus has reached the point of obtaining an image comparable to a photograph or a printed matter which is inexpensive and has excellent image reproducibility and color reproducibility such as sharpness and color property, it is fatal that the surface of the paper is damaged. Problem. Although the improvement is being made on the recording apparatus side and the paper side, the present situation is that it is not possible to obtain an ink jet recording sheet which does not damage the surface while ensuring the ink absorbability which is an important characteristic in ink jet recording.

[0009]

SUMMARY OF THE INVENTION An object of the present invention relates to an ink jet recording sheet, and with the recent increase in the recording speed of ink jet recording methods, a paper feed roll and a conveying device suppress the paper with a high load. Another object of the present invention is to obtain an ink jet recording sheet in which damage to the surface of the paper due to contact with the roll and the device which occurs in order to improve the conveyance accuracy is avoided and the ink absorbability, which is an important feature of the ink jet recording sheet, is secured.

[0010]

As a result of intensive studies, the present inventors have come to invent the ink jet recording sheet of the present invention.

That is, in the ink jet recording sheet of the present invention, at least one or more ink receiving layers are coated on the support, and the surface to be printed is JIS Z874 of 20% or more.
An ink jet recording sheet having a 75-degree specular gloss measured according to 1, wherein the support comprises wood pulp as a main component, and the recording sheet is between the support and the ink receiving layer. And an anchor layer composed of a pigment having a self-adhesive ability.

Further, it is preferable that the coating composition of the anchor layer contains a pigment having self-adhesive ability and an adhesive as main components.

Further, the ink jet recording sheet is
It is preferable that the needle penetration is 4.0 or less after wetting, which is measured based on JIS K2207, because the effect of the present invention is surely obtained.

The ink jet recording sheet of the present invention will be described in detail below.

The ink jet recording sheet of the present invention mainly comprises a support containing wood pulp as a main component, at least one or more ink receiving layers, and a pigment having a self-adhesive ability between the support and the ink receiving layer. An anchor layer as a component is applied.

The ink receiving layer according to the present invention is composed of a coating composition containing a pigment and an adhesive as main components. As the pigment, one or more known white pigments can be used. For example, light calcium carbonate, heavy calcium carbonate, magnesium carbonate, kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide,
Zinc sulfide, zinc carbonate, satin white, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate,
Synthetic amorphous silica, colloidal silica, alumina, colloidal alumina, pseudo-boehmite, aluminum hydroxide,
Examples thereof include white inorganic pigments such as lithopone, zeolite, hydrohalloysite, and magnesium hydroxide, styrene plastic pigments, acrylic plastic pigments, organic pigments such as polyethylene, microcapsules, urea resins, and melamine resins. In particular, a porous pigment is preferable from the viewpoint of ensuring the ink absorption capacity.

Examples of the adhesive include starch derivatives such as oxidized starch, etherified starch and phosphoric acid esterified starch; cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose; casein, gelatin, soybean protein,
Polyvinyl alcohol or a derivative thereof; a conjugated diene copolymer latex such as polyvinylpyrrolidone, a maleic anhydride resin, a styrene-butadiene copolymer, a methylmethacrylate-butadiene copolymer; a polymer or copolymer of acrylic acid ester and methacrylic acid ester. Acrylic polymer latex such as acrylic polymer such as polymer; Vinyl polymer latex such as ethylene vinyl acetate copolymer; or functional group by functional group-containing monomer such as carboxy group of these various polymers Modified polymer latex; Water-based adhesive such as thermosetting synthetic resin such as melamine resin and urea resin; Acrylic ester such as polymethylmethacrylate; Polymer or copolymer resin of methacrylic acid ester; Polyurethane resin, unsaturated polyester resin , Vinyl chloride - vinyl acetate copolymer, polyvinyl butyral and synthetic resin adhesives such as alkyd resins. As the compounding amount of the adhesive,
It is 3 to 70 parts by weight, preferably 5 to 50 parts by weight, based on 100 parts by weight of the pigment. If it is less than 3 parts by weight, the coating strength of the ink receiving layer will be insufficient, and if it exceeds 70 parts by weight, it will absorb the ink. There is a case where the sex is deteriorated.

Further, in the ink receiving layer, as an additive, a dye fixing agent, a pigment dispersant, a thickener, a fluidity improving agent,
Defoamer, foam suppressor, release agent, foaming agent, penetrant, coloring dye,
Coloring pigments, fluorescent whitening agents, ultraviolet absorbers, antioxidants, preservatives, antifungal agents, water resistance agents, wet paper strength enhancers, dry paper strength enhancers and the like can be appropriately added.

The anchor layer according to the present invention is composed of a pigment having a self-adhesive ability, and corresponds to colloidal particles having a particle diameter of several nm to several hundred nm. For example, there are inorganic pigments such as water glass, colloidal silica, colloidal alumina, and pseudo-boehmite. It is also possible to include organic pigments,
Like an emulsion having a core-shell structure in which the shell (outside) has a low Tg and the core (center) has a high Tg, the shell portion melts and has adhesiveness when applied, and the core portion exists as particles. Things are also applicable. In particular, for the anchor layer, an inorganic pigment that forms a hard anchor layer is preferable in order to avoid the surface damage aimed at by the present invention.

Further, since a pigment having a smaller particle size tends to have a higher self-adhesive ability, an adhesive is not required in the coating composition for the anchor layer. However, if the particle size is small, the pigment may fall into the support, so that the particle size is preferably several tens nm or more, although it depends on the type of the support. However, since some pigments have low self-adhesive ability at the particle size, it is possible to use an adhesive together, and the amount of the adhesive is 100 parts by weight or less based on 100 parts by weight of the pigment. If the amount of the adhesive is large, the absorption of ink on the support may be hindered. As the adhesive, those used for the ink receiving layer can be applied. Further, in the anchor layer, as an additive, a dye fixing agent, a pigment dispersant, a thickener, a fluidity improver, a defoaming agent, a foam suppressor, a release agent, a foaming agent,
Appropriately blending penetrants, coloring dyes, coloring pigments, fluorescent whitening agents, ultraviolet absorbers, antioxidants, preservatives, antifungal agents, water resistance agents, wet paper strengthening agents, dry paper strengthening agents, etc. You can also

In particular, a secondary amine which forms an insoluble salt with a sulfonic acid group, a carboxyl group, an amino group, etc. in a water-soluble direct dye or a water-soluble acid dye which is a dye component of an aqueous ink,
When a cationic dye fixing agent composed of a tertiary amine and a quaternary ammonium salt is blended, the dye is captured in the ink receiving layer, so that the color is improved and the ink is dropped by water absorption due to the formation of an insoluble salt. It is preferable because it suppresses the flow and bleeding of water.

The method of applying the ink receiving layer and the anchor layer is carried out by using various devices such as a blade coater, a roll coater, an air knife coater, a bar coater, a rod blade coater, a curtain coater, a short dwell coater and a size press. Can be used off-machine. Also, after coating, machine calendar, TG
It is also possible to perform a flattening finish using a calendar device such as a calendar, super calendar, or soft calendar. The coating amounts of the ink receiving layer and the anchor layer are 1 g / m ² or more, although they vary depending on the required characteristics, the type of support, and the like.

It is also possible to coat one or more ink-receiving layers on the support, and to protect the receiving layer from gloss deterioration in order to impart gloss to the receiving layer and to protect the receiving layer from deterioration due to ultraviolet rays. Further, a coating layer such as an ultraviolet absorbing layer may be further provided. The same method as that for the ink receiving layer is used for coating and flattening.

The support used in the present invention is LB
Chemical pulp such as KP, NBKP, GP, PGW, RM
P and TMP, CTMP, CMP, CGP and other mechanical pulps, DIP and other waste paper pulps and other wood pulps and conventionally known pigments as the main components, and adhesives and sizing agents and fixing agents, yield improving agents, cationizing agents. , Raw paper manufactured by various devices such as fourdrinier paper machine, cylinder paper machine, twin wire paper machine, etc., mixed with at least one kind of various additives such as paper strength enhancer, and further starch, polyvinyl It also includes size-pressed with alcohol or the like and base paper provided with an anchor coat layer, and coated paper such as art paper, coated paper, cast coated paper provided with a coat layer thereon. Such a base paper and a coated paper may be provided with the coating layer according to the present invention as they are, or a calender device such as a machine calender, a TG calender or a soft calender may be used for the purpose of controlling the flatness. . The basis weight of the support is usually 40 to 300 g / m ² , but is not particularly limited.

The aqueous ink referred to in the present invention is a recording liquid containing the following colorant, liquid medium, and other additives.

The colorant is a water-soluble dye such as a direct dye, an acid dye, a basic dye, a reactive dye or a food dye.

As the solvent of the aqueous ink, water and various water-soluble organic solvents such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, C1-C4 alkyl alcohols such as isobutyl alcohol; amides such as dimethylformamide and dimethylacetamide; ketones or ketone alcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane; polyethylene glycol, polypropylene glycol Polyalkylene glycols such as; ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodig Call, hexylene glycol, an alkylene group such as diethylene glycol 2
~ 6 alkylene glycols; lower alkyl ethers of polyhydric alcohols such as glycerin, ethylene glycol methyl ether, diethylene glycol methyl (or ethyl) ether, and triethylene glycol monomethyl ether.

Among many of these water-soluble organic solvents,
Polyhydric alcohols such as diethylene glycol and lower alkyl ethers of polyhydric alcohols such as triethylene glycol monomethyl ether and triethylene glycol monoethyl ether are preferred.

Other additives include, for example, a pH adjusting agent, a sequestering agent, an antifungal agent, a viscosity adjusting agent, a surface tension adjusting agent, a wetting agent, a surfactant, and a rust preventive agent.

The ink jet recording sheet according to the present invention is not limited to being used as an ink jet recording sheet, and may be used as any recording sheet using a liquid ink during recording. For example, an ink sheet in which a heat-fusible ink containing a heat-fusible substance, a dye or pigment as a main component is applied on a thin support such as a resin film, high-density paper, or synthetic paper is heated from the back surface of the ink sheet, An image-receiving sheet for thermal transfer recording that melts and transfers, an inkjet recording sheet that heat-melts a heat-melting ink into fine droplets for flight recording, an inkjet recording sheet that uses an ink in which an oil-soluble dye is dissolved in a solvent, photopolymerization An image receiving sheet corresponding to a light and pressure sensitive donor sheet using microcapsules containing a type monomer and colorless or colored dyes and pigments can be mentioned.

The common point of these recording sheets is that the ink is in a liquid state at the time of recording. The liquid ink permeates or spreads in the depth direction or the horizontal direction of the ink receiving layer of the recording sheet before being cured, solidified, or fixed. The various recording sheets described above require absorptivity according to their respective systems, and the inkjet recording sheet of the present invention may be used as the various recording sheets described above.

Further, the ink jet recording sheet of the present invention may be used as a recording sheet for heating and fixing the toner of the electrophotographic recording system which is widely used in copying machines, printers, etc., and an adhesive layer may be provided. It can also be used for labels.

In order to prevent damage to the surface of the recording sheet, which is the object of the present invention, it is possible to finish the ink-receiving layer by making it hard, but in order to ensure transportability in the ink jet recording apparatus. In order to obtain a smooth surface, a flattening treatment is indispensable. However, this treatment reduces the absorption capacity of the ink receiving layer, resulting in unacceptable deterioration of ink absorption.

Therefore, it is conceivable to increase the coating amount of the ink receiving layer. However, the increased amount of the layer causes peeling of the coating layer due to reduction of the coating layer strength and reduction of printing density due to increase of light scattering. Moreover, the amount of coating cannot be simply increased.

[0035]

[Action]

It has been shown that it is difficult to deal with the surface damage and the ink absorptivity, which are the contradictory characteristics, only with the ink receiving layer. However, as shown in the present invention, ink absorbency is ensured by a support mainly composed of wood pulp and an ink receiving layer, and surface damage is caused by an anchor provided between the support and the ink receiving layer. The object of the present invention can be achieved by preventing with a layer, that is, by functionally separating the layer structure of the inkjet recording sheet.

By using a wood pulp as a main component for the support, it becomes possible to impart ink absorption characteristics to the support, and it is possible to obtain an ink jet recording sheet having an absorption capacity combined with the ink receiving layer. Become. But,
The support is soft, and when the load generated by the contact between the surface of the inkjet recording sheet and the inkjet recording device is transmitted from the surface and reaches the support, the support is deformed to change the surface shape of the recording sheet. Changing, that is,
Like the damage to the surface, it causes deterioration in appearance.

Further, the deformation of the support is more likely to occur due to the absorption of ink after printing, and the printed surface state is particularly important for determining the quality of image. The surface damage that occurs after printing is caused by the swelling of the wood pulp that is the main component of the support due to the permeation of the ink into the support, and the swelling is caused by the contact with the inkjet recording device. External force hinders
The surface where the external force is applied has a concave shape, and the entire surface of the recording sheet has an uneven shape, which greatly impairs the appearance.

Particularly, the surface of the ink jet recording sheet is J
It was found that the degree of surface damage was visually recognized when the 75-degree specular glossiness measured according to IS Z8741 was 20% or more. This is because the reflection direction of light on the surface is different due to the damage, and the glossy portion and the non-glossy portion are visually recognized, resulting in deterioration of image quality. The matte or matte ink jet recording sheet having a gloss level of less than 20% is hard to be visually recognized because the surface is damaged and the light reflection amount is small even if the light reflection direction is different. Does not significantly decrease

The present inventors sought to prevent damage to the surface while making the most of the ink absorbency of the support, and provided a hard anchor layer between the support and the ink receiving layer. It has been found that the object of the present invention is suitable when the anchor layer has a function of transmitting the ink from the ink receiving layer to the support. As a coating composition suitable for the anchor layer, a polymer having a high film-forming property that does not allow ink to easily pass through causes deterioration in ink absorbability, and thus it is necessary to apply a pigment having a self-adhesive ability. The pigment develops an adhesive function by association between the pigments, and also has fine pores through which the ink can pass. Furthermore, when the pigment is an inorganic pigment, the coating layer formed by this association bond becomes hard and it is possible to prevent surface damage, which is more preferable.

The degree of damage on this surface is determined by JIS.
It was found that there is a high correlation with the penetration measured according to K2207. Further, pure water was dropped on the printing surface of the ink jet recording sheet, wetted for 5 seconds, and then the penetration measured by this penetration measuring method (hereinafter, abbreviated as penetration).
Is 4.0 or less, the object of the present invention is further secured. When the penetration is more than 4.0, the ink absorbability is excellent, but surface damage may occur depending on the amount of ejected ink.

[0042]

EXAMPLES The present invention will be described below with reference to examples.
The invention is not limited to these examples. Also,
Unless otherwise specified, "parts" and "%" shown in the examples mean absolute dry weight parts and absolute dry weight%.

<Support> The composition is LBKP (freeness 40
0 parts of 0 mlcsf) and 20 parts of NBKP (freeness of 480 mlcsf) to 100 parts of wood pulp, 8 parts of light calcium carbonate, 8 parts of talc, 8 parts of heavy calcium carbonate, 0.2 part of commercial sizing agent, sulfuric acid 0.4 part of the band and 0.03 part of the commercial yield improver were mixed and mixed, and a support having a basis weight of 90 g / m ² was prepared using a Fourdrinier paper machine. After that, oxidized starch (M
S3800: manufactured by Nippon Shokuhin Kogyo Co., Ltd.) could be size-pressed to a dry coating amount of 2 g / m ² .

Each of the examples and comparative examples was obtained by laminating an anchor layer and an ink receiving layer on the support.

Example 1 (Anchor Layer) The coating composition for the anchor layer consisted of 100 parts of colloidal silica (Snowtex-O; particle size 20 μm: Nissan Chemical Industries Ltd.). The composition was coated using a roll coater to a dry coating amount of 2 g / m ² and dried. (Ink receiving layer) An ink receiving layer was coated on the anchor layer. The ink receiving layer is composed of a lower layer coated on the anchor layer and an upper layer further laminated on the lower layer. The coating composition of the lower layer is amorphous silica (Mizukasil P78D:
100 parts of Mizusawa Chemical Co., Ltd., 30 parts of polyvinyl alcohol (PVA 117: manufactured by Kuraray Co., Ltd.) as an adhesive agent, and 20 parts of a commercially available polyvinyl amine-based polymer as a dye fixing agent were mixed to obtain a solid content concentration of 18%. . The composition is
It was coated and dried so that the dry coating amount was 10 g / m ² .

The coating composition for the upper layer is colloidal particles (Snowtex XL, manufactured by Nissan Chemical Industries, Ltd.) 50 as a pigment.
Parts, 50 parts of an acrylic organic pigment (Movinyl 790: manufactured by Hoechst Synthetic), and 15 parts of an acrylic emulsion (Movinyl 8020: manufactured by Hoechst Synthetic) as an adhesive were prepared, and the solid content concentration was adjusted to 40%. . The composition was coated and dried to a dry coating amount of 12 g / m ^2, and then supercalendered at a linear pressure of 100 kg / cm to obtain an inkjet recording sheet of Example 1.

Example 2 (Anchor Layer) The coating composition for the anchor layer consisted of 100 parts of colloidal silica (Snowtex XL; particle size 40 nm: Nissan Chemical Industries Ltd.). The composition was coated using a roll coater to a dry coating amount of 2 g / m ² and dried. (Ink Receiving Layer) The ink receiving layer was applied under the same coating composition and conditions as in Example 1 and subjected to super calender treatment to obtain an ink jet recording sheet of Example 2.

Example 3 (Anchor Layer) The coating composition for the anchor layer was 100 parts of colloidal silica (PST-1; particle diameter 100 nm: Nissan Chemical Industries, Ltd.), and polyvinyl alcohol (P
VA117: manufactured by Kuraray Co., Ltd.). The composition was coated using a roll coater to a dry coating amount of 2 g / m ² and dried. (Ink Receiving Layer) An ink receiving layer was applied under the same coating composition and conditions as in Example 1 and subjected to a super calendar treatment to obtain an inkjet recording sheet of Example 3.

Example 4 (Anchor Layer) The coating composition for the anchor layer was composed of 100 parts of colloidal silica (PST-1; particle size 100 nm: manufactured by Nissan Chemical Industries, Ltd.) and 30 parts of a commercially available styrene-butadiene latex as an adhesive. Become. The composition was coated using a roll coater to a dry coating amount of 2 g / m ² and dried. (Ink Receiving Layer) The ink receiving layer was applied under the same coating composition and conditions as in Example 1 and subjected to super calender treatment to obtain an inkjet recording sheet of Example 4.

Example 5 (Anchor Layer) The coating composition of the anchor layer was 100 parts of alumina sol (alumina sol-520; particle size 10 nm: manufactured by Nissan Chemical Industries, Ltd.), and polyvinyl alcohol (PVA 117: manufactured by Kuraray Co., Ltd.) as an adhesive. It consists of 30 parts. The composition was coated using a roll coater to a dry coating amount of 2 g / m ² and dried. (Ink Receiving Layer) The ink receiving layer was applied under the same coating composition and conditions as in Example 1 and subjected to supercalendering treatment to obtain an inkjet recording sheet of Example 5.

Comparative Example 1 (Anchor Layer) For the anchor layer, a commercially available styrene-butadiene latex was used with a roll coater to provide a dry coating amount of 2 g /
It was obtained by coating so as to be m ² and drying. (Ink Receiving Layer) The ink receiving layer was applied under the same coating composition and conditions as in Example 1 and subjected to super calender treatment to obtain an inkjet recording sheet of Comparative Example 1.

Comparative Example 2 (Anchor Layer) The coating composition for the anchor layer was 100% heavy calcium carbonate (Escalon # 100: Sankyo Seiko Co., Ltd.).
And polyvinyl alcohol (PVA11
7: Kuraray Co., Ltd.) 10 parts. The composition was coated on a roll coater to a dry coating amount of 2 g / m ² and dried. (Ink Receiving Layer) The ink receiving layer was applied under the same coating composition and conditions as in Example 1 and subjected to a super calendar treatment to obtain an inkjet recording sheet of Comparative Example 2.

COMPARATIVE EXAMPLE 3 A commercially available white PET (polyethylene terephthalate) sheet was used as the support, an anchor layer was not provided, and the support was coated on the support with the same coating composition and conditions as in Example 1, and supercalendered. An ink jet recording sheet of Comparative Example 2 was obtained.

Table 1 shows the evaluation results of Examples 1 to 5 and Comparative Examples 1 to 3. In addition, each measurement item in Table 1 was performed based on the following method.

<Penetration> The ink jet recording sheet and pure water were placed under the environment specified in JIS P8111 for 24 hours.
I left it for more than an hour. 10 μl of pure water was dropped on the surface to be printed, and after 5 seconds, the penetration was measured according to JIS K2207. For penetration measurement, a penetration tester (AN-20
0: manufactured by Nippon Oil Testing Machine Industry Co., Ltd.) was used. <Specular gloss> Ink jet recording sheet is JIS P
It was left to stand for 24 hours or more in the environment specified by 8111.
After that, the measurement was performed based on the 75 degree specular gloss level defined in JIS Z8741 (VGS-1001DP:
(Made by Nippon Denshoku Industries Co., Ltd.). The display is%.

<Ink Absorption 1> Using a commercially available ink jet printer (Design jet650C: manufactured by Hewlett Packard), double-color printing of cyan ink and magenta ink is performed, and a blank sheet is printed on the printing surface 10 seconds after printing. The state of transfer to a blank sheet was visually evaluated by the following criteria. If the transfer occurs, stains are generated during transportation. The A evaluation is not a problem in practical use. A: No ink transfer was observed on the white paper. C: Ink transfer is observed on white paper.

<Ink Absorbency 2> Using the above-mentioned ink jet printer, images composed of cyan ink and magenta ink were made to be adjacent to each other, and a straight line of an overlapping portion was evaluated according to the following criteria. Linearity is related to ink absorbency, and low linearity results in poor color and sharpness. The A or B evaluation is not a problem in practical use. A: Excellent linearity. B: A whisker-like spread is slightly seen in the order of several tens of μm in the adjacent portion, but there is no problem. C: A whisker-shaped spread occurs on the order of several mm, which affects the image quality.

<Surface Damage State> Using the above-mentioned ink jet printer, a heavy color step wedge (gray level: 5% to 10%) composed of cyan ink and magenta ink is used.
0%; 5% step unit) was printed on the ink jet recording sheet, and the damage on the printing surface by the blade-shaped roll installed in the printer conveyance portion was visually evaluated. The higher the gradation level (the greater the amount of ejected ink), the greater the damage to the printed surface. However, if the gradation level at which the damage is visually observed is 70% or more, the surface quality that causes a problem in image quality will be a practical problem. Does not cause damage.

[0059]

[Table 1]

As shown in Examples 1 to 5, by providing an anchor layer composed of a pigment having a self-adhesive ability between the support and the ink receiving layer, the ink absorbability and the state of surface damage can be improved. It can be seen that an inkjet recording sheet suitable for the purpose of the present invention can be obtained. However, it is understood that in Comparative Examples 1 and 2 in which the anchor layer is provided using polyvinyl alcohol or latex, the ink absorbency is lowered and the surface is unacceptably damaged. The decrease in ink absorbency is due to the fact that the anchor layer impedes the penetration of ink into the support, and the deterioration of the surface state is due to the fact that the film of the anchor layer is soft and easily deformed. are doing.

Comparative Example 3 shows that a support which does not absorb ink causes a problem in ink absorbency. Further, the ink jet recording sheet which can obtain the ink absorbency and the state of surface damage aimed at by the present invention has a penetration of 4.
It is shown to be 0 or less.

[0062]

According to the present invention, an anchor layer and an ink receiving layer are laminated on a support containing wood pulp as a main component, and the anchor layer comprises a pigment having a self-adhesive ability. With the configuration, it is possible to avoid the damage on the surface caused by the contact with the inkjet recording apparatus and the transporting section in the apparatus, and to obtain the inkjet recording sheet that secures the ink absorbability.

Claims (3)

[Claims] 1. A JIS in which at least one or more ink receiving layers are coated on a support and the surface to be printed is 20% or more.
An ink jet recording sheet having a 75-degree specular gloss measured according to Z8741, wherein the support contains wood pulp as a main component, and the recording sheet is between the support and the ink receiving layer. An inkjet recording sheet having an anchor layer composed of a pigment having self-adhesive ability. 2. The ink jet recording sheet according to claim 1, wherein the anchor layer comprises a coating composition containing a pigment having a self-adhesive ability and an adhesive as main components. 3. The ink jet recording sheet according to claim 1, wherein the ink jet recording sheet has a penetrability measured after being wet of 4.0 or less according to JIS K2207.