JPH09277298A - Method and apparatus for manufacturing fine foam - Google Patents

Abstract

(57) Abstract: [PROBLEMS] To provide a manufacturing method for continuously molding a fine foam by achieving accurate measurement and improvement of gas solubility in a molten resin. SOLUTION: A molten resin metering and shutoff nozzle 6
Is carried out by rotating the screw 3 incorporated in the heating cylinder 1 to inject gas into the stirring cylinder 2,
The gas and the molten resin are agitated by rotating the rotary blade 29 provided inside the shut-off nozzle 6, and injection into the mold cavity 7 is performed by the screw extruding portion 5 or the plunger.
Step 18 to form a fine foam continuously.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for producing a fine foam body in which a gas is melted in a molten resin and is injected into a mold for molding.

[0002]

2. Description of the Related Art As a method for producing a fine foam body in which a gas is melted in a molten resin and is injected into a mold to form a fine foamed body, the measurement of the molten resin and the transfer to a stirring cylinder are built in a heating cylinder as in the present invention. There is no production method in which molding is performed by rotating the screw, stirring the gas and the molten resin, and injecting the molten resin in which the gas is dissolved into the mold cavity by the reciprocating motion and the pushing operation of the screw. Conventionally, gas is injected into a heating cylinder, and the gas and the molten resin are stirred and measured by rotating a screw built in the heating cylinder. Also,
The injection of the molten resin in which the gas was dissolved into the mold cavity was also carried out by the extrusion operation of the screw (Patent No. USP 5,160,674, microcrystalline plastic of semi-crystalline polymer material). This method is exactly the same as the general injection molding that has been widely performed in the past, except for the gas injection step. That is, the stirring and metering of the gas and the molten resin are performed by rotating the screw. This can be expected to achieve uniform agitation, and the facility cost can be reduced by using only a gas supply mechanism as ancillary facility.

[0003]

FIG. 10 shows a conventional injection mechanism section. Its structure is heating cylinder 1, screw 3,
A hopper 11, a shutoff nozzle 6, a motor 13, a gas supply unit 23, and a gas pipe 24. The pellet-shaped resin 12 in the hopper 11 is transferred to the high temperature heating cylinder 1 by the rotation of the screw 3 and melted therein, and is mixed with the gas injected from the gas supply port 23 and stirred. Then, the molten resin is injected into the mold cavity 7 through the shutoff nozzle 6 by the forward movement of the screw 3. The amount of resin injected into the mold cavity 7, that is, the amount of resin, is determined by the rotation speed of the screw 3 and time. Therefore, when the internal pressures of the heating cylinder 1 and the shutoff nozzle 6 are almost zero or low, the screw 3 rotates normally, so that the measurement of the molten resin is always constant and continuous production is possible.

However, when the gas is mixed with the molten resin as in the prior art, the molten resin in which the high-pressure gas is dissolved remains inside the heating cylinder 1 and the shutoff nozzle 6 in the first injection stage. Therefore, at the time of measurement for the next injection, this residual pressure pushes back the screw 3 before the screw 3 rotates, making it impossible to perform a predetermined measurement. Therefore, there is a problem that continuous molding cannot be performed. In order to solve this problem, it is necessary to add a step of removing the residual pressure after each injection molding or to modify the screw 3 so that the screw 3 is not pushed back by the residual pressure. However, there are still problems in continuous production.

The object of the present invention is to solve these problems of the prior art.

[0006]

In order to solve the problems of the prior art, a molten resin in which a gas is melted is injected into a mold cavity to continuously mold a three-dimensionally shaped fine foam molded product such as a box. In order to provide a manufacturing method to do, first, the molten resin is measured and transferred to the stirring cylinder by rotating a screw incorporated in the heating cylinder, and then gas is injected into the stirring cylinder,
The stirring of the gas and the molten resin and the injection of the molten resin melted in the gas into the mold cavity were performed by the reciprocating movement of the screw and the pushing operation.

The gas and the molten resin are agitated by passing the molten resin through the groove of the sleeve having the outer peripheral groove by the reciprocating motion of the screw in a stirring cylinder containing the sleeve having the outer peripheral groove, and shutting by the resin. The rotary blade provided inside the off-nozzle was rotated to repeatedly convey the screw forward and backward of the extrusion portion of the screw. Next, the injection into the mold cavity was carried out by closing the resin flow passage holes connected to the plurality of grooves of the sleeve with outer peripheral groove with a needle valve and then extruding the screw.

The heating cylinder having a built-in screw and the stirring cylinder having a sleeve with an outer peripheral groove and having an extruding portion of the screw were arranged on the same axis. The rotation of the screw was performed by a motor installed coaxially, and the pushing operation of the screw was performed by a hydraulic cylinder.

Even if a manufacturing apparatus in which a heating cylinder having a built-in screw and a stirring cylinder having a sleeve with an outer peripheral groove and having a plunger are arranged coaxially or separately is used, a three-dimensionally shaped fine foam molded article can be obtained. Can be molded continuously.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a method for producing a fine foam and an apparatus therefor according to the present invention will be described in detail with reference to the drawings.

(Embodiment 1) FIG. 1 is a sectional view of an injection mechanism portion of an injection molding apparatus for producing a fine foam of the present invention. 2 is a cross-sectional view of the stirring cylinder of FIG. 1, and FIG. 3 is a perspective view of a sleeve with an outer peripheral groove incorporated in the stirring cylinder. FIG. 4 is a perspective view of a rotary blade provided inside the shut-off nozzle of FIG. FIG. 5 is a cross-sectional view of the grooved sleeve, the rotary blade, and the shafted sleeve. FIG. 6 is a side view of a grooved sleeve having rotating blades and a single groove and a plurality of grooves.
The box body of the present invention provided on the side surface of the grooved sleeve is a finely foamed product. FIG. 7 is a sectional view of FIG.

A method for continuously producing a three-dimensional fine foam molded article of the present invention will be described with reference to FIGS. 1 to 8.
In FIG. 1, 2 is a stirring cylinder, 4 is a screw flight part, 5 is a screw extrusion part, 7 is a mold cavity part, 8 is a resin flow path hole, 9 is a needle valve, 10 is a check valve, and 13 is a motor. ,
Reference numeral 16 is an outer peripheral grooved sleeve, 17 is a groove portion of 16, 16 is a pressure receiving ring, 28 is a grooved sleeve, 29 is a rotary blade, and 30 is a sleeve with a shaft. The pellet-shaped resin 12 in the hopper 11 is transferred to the high temperature heating cylinder 1 by the screw flight part 4 by the rotation of the screw 3 directly connected to the motor 13 and melted,
After being weighed by a predetermined amount, it is transferred to the stirring cylinder 2. At this time, the pressure receiving ring 25 moves forward by the molten resin pressure, and the resin flow path is secured. The screw 3 is arranged in front of the stirring cylinder 2 because the injection is completed. Next, high-pressure carbon dioxide gas is injected from the gas supply port 23, and the reciprocating motion of the screw 3 and the rotary blade 29 provided inside the shutoff nozzle 6 are provided.
The rotation of the resin stirs the molten resin and the gas. In this stirring, first, when the screw 3 is pushed back by the hydraulic cylinder 26, the molten resin injected with gas passes through the plurality of groove portions 17 of the outer peripheral grooved sleeve 16 from the resin flow path hole 8 and the molten resin of the stirring cylinder 2 flows. Transported forward, where the shaft-off sleeve 30 and grooved sleeve 28 inside the shut-off nozzle 6
The rotary blade 29 is rotatably attached to the rotary blade 29 and is agitated by the rotation of the rotary blade 29. Next, when the screw 3 is pushed forward, the molten resin becomes
Between the blades of the rotary blade 29, the groove portion of the grooved sleeve 28 and the plurality of groove portions 17 of the outer peripheral grooved sleeve 16 from the resin flow path hole 8
And is transferred to the rear of the stirring cylinder 2. By repeating this operation, the gas and the molten resin are sufficiently stirred. During this stirring operation, the pressure receiving ring 25 provided inside the heating cylinder 1 is pressed against the screw 3 by the pressure during stirring, so that the molten resin does not flow back to the heating cylinder 1 side. The check valve 10 can prevent the molten resin from flowing back into the gas pipe 24.

The injection of the molten resin, in which the gas is dissolved by stirring, into the mold cavity 7 is performed by the needle valve 9 through the resin flow path hole 8
Is closed, and then the screw 3 is advanced to perform the operation. That is, the molten resin in the stirring cylinder 2 is injected into the mold cavity 7 from the shutoff nozzle 6 as the screw 3 advances. A shaft sleeve 30, a grooved sleeve 28, and a rotary blade 29 are installed inside the shutoff nozzle 6, but they do not adversely affect the injection.

In this embodiment, a screw flight part 4 and an extruding part 5 are provided on the integrated screw 3, the molten resin is transferred and measured by rotating the screw 3, and the gas and the molten resin are stirred by the reciprocating motion of the screw 3. The rotation of the rotary blade 29 provided inside the shut-off nozzle 6 is performed so that the injection into the mold cavity is performed by the pushing operation of the screw 3. Therefore, accurate measurement can be performed and continuous production can be performed.

Further, since the gas and the molten resin can be sufficiently stirred, the solubility of the gas in the molten resin can be improved.

FIG. 7 shows a fine foam produced according to the present invention. The cross section is shown in FIG. The foam has a closed cell structure and is a fine foam having a cell diameter of 5 to 20 μm.

(Embodiment 2) FIG. 9 is another embodiment for producing the fine foam of the present invention and is a sectional view of an injection mechanism portion of an injection molding apparatus. In this embodiment, the molten resin is weighed and transferred to a stirring cylinder 2 equipped with a shut-off nozzle 6 by rotating a screw 3 incorporated in the heating cylinder 1.
The gas is injected into the stirring cylinder 2 arranged coaxially with, and the reciprocating motion and the extrusion of the plunger 18 provided in the stirring cylinder 2 for stirring the gas and the molten resin and injecting the molten resin in which the gas is melted into the mold cavity 7. I decided to do it in motion.

The method of stirring the gas and the molten resin and the method of injecting the molten resin in which the gas is dissolved into the mold cavity 7 are the same as those in the first embodiment of the invention.

Further, mechanically, the screw 3 and the plunger
The screw 3 has a hollow shape so that the screw 18 can be operated coaxially and operated, and the plunger 18 is inserted into the screw 3 to form a hydraulic cylinder.
Directly connected to 26. The rotation of the screw 3 is performed by a motor 13 installed on another shaft via a sprocket 15 and a chain 14.

In the embodiment of the present invention, the exact measurement can be performed exactly as in the case of the embodiment 1, and the continuous production can be realized. Moreover, since the gas and the molten resin can be sufficiently stirred, the solubility of the gas in the molten resin can be improved.

(Embodiment 3) FIG. 10 is a sectional view of an injection mechanism portion of an injection molding apparatus according to still another embodiment of the present invention for producing a fine foam of the present invention. In this embodiment, the heating cylinder 1 with the built-in screw 3 and the shutoff nozzle 6 are fixed,
Further, the agitating cylinder 2 having the sleeve 16 with the outer peripheral groove built therein and having the plunger is arranged on a different axis. The constituent elements of each unit and their operations are almost the same as those in the first embodiment.
Also, the effect obtained by this is exactly the same as in the case of the first embodiment of the invention. By disposing the heating cylinder 1 and the stirring cylinder 2 equipped with the shut-off nozzle 6 separately on different axes as in the present embodiment, the screw 3 built in the heating cylinder 1 is hollow as in the second embodiment. In addition, a sprocket and a chain for transmitting the rotation of the motor 12 to the screw 3 are unnecessary. However, the first embodiment of the invention
Also, it is necessary to make the space wider than in the case of the coaxial arrangement in the second embodiment. In the case of the present embodiment, the same function can be obtained by arranging the heating cylinder 1 having the screw 3 therein horizontally, the plunger 18 therein, and the stirring cylinder 2 with the shut-off nozzle 5 fixed therein arranged vertically.

[0022]

EFFECTS OF THE INVENTION According to the present invention, a method for producing a fine foam, in which a gas is dissolved in a molten resin and the mixture is injected into a mold to be molded,
The molten resin is weighed and transferred to a stirring cylinder equipped with a shut-off nozzle by rotating the screw built into the heating cylinder, gas is injected into the stirring cylinder, and the gas and molten resin are stirred into the screw or stirring cylinder. The reciprocating motion of the plunger provided and the rotary motion of the rotary blade provided inside the shut-off nozzle were used to inject the molten resin in which the gas was melted into the mold cavity by the pushing operation of the screw or the plunger. The resin can be measured reliably, and the gas and the molten resin are well agitated. This allows continuous molding. Further, according to the present invention, both a heating cylinder having a built-in screw and a shut-off nozzle fixed, and an agitating cylinder having a sleeve with an outer peripheral groove arranged on the same shaft or on another shaft are possible. Yes, you can select either one as needed.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an injection mechanism portion of an injection molding device that manufactures a fine foam according to this embodiment.

FIG. 2 is a cross-sectional view of the stirring cylinder of FIG.

FIG. 3 is a perspective view of a sleeve with an outer peripheral groove built in the stirring cylinder of FIG.

FIG. 4 is a perspective view of rotary vanes provided inside the shut-off nozzle of FIG.

5 is a cross-sectional view of a grooved sleeve, a rotating blade, and a shafted sleeve provided inside the shut-off nozzle of FIG.

FIG. 6 is a side view of a grooved sleeve having rotating blades and a single groove and a plurality of grooves.

FIG. 7 is a perspective view of a box-shaped fine foam molded by the manufacturing apparatus of the present invention.

8 is a partial cross-sectional view of FIG.

FIG. 9 is a cross-sectional view of an injection mechanism portion of an injection molding apparatus that manufactures a fine foam according to another embodiment of the present invention.

FIG. 10 is a cross-sectional view of an injection mechanism portion of an injection molding device that manufactures a fine foam according to another embodiment of the present invention.

FIG. 11 is a cross-sectional view of an injection mechanism portion of an injection molding device that manufactures a foam according to a conventional technique.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Heating cylinder, 2 ... Stirring cylinder, 3 ... Screw, 4 ... Screw flight part, 5 ... Screw extrusion part, 6 ... Shut-off nozzle, 7 ... Mold cavity part, 8 ... Resin channel hole, 9 ... Needle valve , 10 ... Check valve, 11 ... Hopper, 12 ... Pellet resin, 13 ... Motor, 16 ... Sleeve with outer peripheral groove,
23 ... Gas supply port, 28 ... Grooved sleeve, 29 ... Rotating blade,
30 ... Sleeve with shaft.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Makoto Iida 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Stock Engineering Co., Ltd.

Claims (8)

[Claims] 1. A method for manufacturing a fine foam body, in which a molten resin in which gas is dissolved is injected into a mold to be molded, and the molten resin is measured and transferred to a stirring cylinder equipped with a shut-off nozzle to a heating cylinder. By rotating the built-in screw,
A fine foam characterized in that the gas is injected into the stirring cylinder, and the stirring of the gas and the molten resin and the injection of the molten resin into the mold cavity are performed by the reciprocating motion of the screw and the pushing operation. Manufacturing method. 2. The stirring of the gas and the molten resin is carried out in a stirring cylinder containing a sleeve with an outer peripheral groove through a plurality of grooves formed on the outer periphery of the sleeve with the outer peripheral groove by reciprocating motion of a screw. The method for producing a fine foam according to claim 1, wherein the molten resin is repeatedly transferred forward and backward in the stirring cylinder, and rotating blades provided inside the shutoff nozzle are rotated. 3. A rotary blade provided inside the shut-off nozzle is rotatably installed by a sleeve with a shaft and the sleeve with a groove, and the molten resin is rotated by hitting a blade portion of the rotary blade, The apparatus for producing a fine foam according to claim 2, wherein the molten resin is stirred. 4. The fine foam according to claim 1, wherein the screw is composed of a flight part for transferring the molten resin by rotation and an extruding part for stirring the molten resin and injecting the molten resin into a mold cavity. Manufacturing equipment. 5. The molten resin is measured and transferred to a stirring cylinder equipped with a shut-off nozzle by rotating a hollow screw incorporated in the heating cylinder, and a gas is supplied to the stirring cylinder arranged coaxially with the heating cylinder. Is injected, and the stirring of the gas and the molten resin and the injection of the molten resin in which the gas is dissolved into the mold cavity are performed by a plunger inserted into the hollow screw. 6. Rotation of a screw for measuring the molten resin and transferring it to a stirring cylinder is performed by a motor installed on a shaft different from the screw via a sprocket and a chain, and stirring gas and molten resin. The plunger is inserted inside the hollow screw and is directly connected to the hydraulic cylinder. 7. The molten resin is measured and transferred to a stirring cylinder equipped with a shut-off nozzle by rotating a screw incorporated in the heating cylinder, and gas is supplied to the stirring cylinder arranged on a separate axis from the heating cylinder. A method for producing a fine foam, comprising injecting and stirring the gas and the molten resin and injecting the molten resin in which the gas is dissolved into the mold cavity by a plunger provided in the stirring cylinder. 8. The gas and the molten resin are agitated by a plurality of grooves formed on the outer periphery of the outer peripheral grooved sleeve by the reciprocating motion of the plunger in the stirring cylinder containing the outer peripheral grooved sleeve. The production of the fine foam according to claim 6 or 7, wherein the molten resin is repeatedly transferred to the front and the rear in the stirring cylinder via a rotary blade provided inside the shutoff nozzle. Method.