JPH0952247A - Bonding injection molding method - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To provide a smooth injection molding product having excellent surface transferability, high adhesion between a resin sheet and a molten resin (matrix resin), and a smooth and high-quality bonded injection-molded product. A combined injection molding method is provided. SOLUTION: This is a bonding injection molding method in which resin sheets S are bonded together, and the resin sheet S is arranged in advance on the mold cavity surface before injection filling of the resin, and the mold is closed to inject and fill the molten resin. While or after injection filling, the mold surface temperature is heated to near the softening point temperature of the resin sheet S, and then the mold 8 is cooled to a temperature at which it can be solidified by cooling and then the mold 8 is opened. I took out the molded product.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bonding injection molding method in which a resin sheet is bonded to the surface of a molded product molded by an injection molding machine, and in particular, the fusion property between the resin sheet and the molten resin to be injected and filled. The present invention relates to a bonding injection molding method capable of obtaining a molded article excellent in high transfer and high surface property while improving the transferability.

[0002]

2. Description of the Related Art An injection molding machine opens a pair of left and right molds,
It is composed of a mold closing device that closes the mold, an injection device that injects and fills the molten resin into the cavities of both molds, and a control device that gives an operation command to the movable parts of these devices. In general,
When a resin sheet is pasted on a resin surface with an injection molding machine, for example, as shown in FIG. 6, a movable mold attached to a movable platen with a fixed platen and a movable platen opened. After the resin sheet to be attached is attached to the cavity surface of the mold, the mold is closed, the tip of the injection device is pressed against the back surface of the fixed plate, and the pair of left and right molds (fixed mold and movable mold) are closed. The method of injection molding the molten resin into the cavity space partitioned and formed by molding was adopted.

[0003]

However, such a conventional bonded injection-molded product is a bonded product that is wrinkled or distorted during the flow of the molten resin in which the resin sheet is injected and filled by the injection device. It may remain on the resin sheet surface of the molded product, or a gas such as air or gas may enter between the resin sheet and the resin so that a smooth surface may not be obtained. It was not found in the bonded molded product, and there was the inconvenience of deteriorating the surface property and significantly impairing the commercial value.

[0004]

[Means for Solving the Problems] In order to solve the above problems and obtain a high-transfer and high-quality bonded injection-molded product with good adhesion between a resin sheet and a parison, smoothness, and gloss. In the present invention, in the first aspect of the invention, the movable platen is arranged so as to come in contact with and separated from the fixed platen, and the movable platen is provided in a cavity formed by a pair of left and right dies attached to the fixed platen and the movable platen. In an injection molding machine for injecting and molding a resin through an injection device, a resin sheet is previously arranged on a mold cavity surface before injection and filling of the resin, and the mold is closed to inject and fill the molten resin, or , After injection filling,
After heating the mold surface temperature to the softening point temperature of the resin sheet or higher, the mold was cooled and solidified to cool the mold to a temperature at which the mold could be taken out, and then the mold was opened to take out the molded product. Further, in the second invention, in the first invention, the diameter formed by punching on the surface of the resin sheet is 0.
1 to 1 mm fine through-holes are arranged in an area of 100 cm ^{2 in an amount of} 10 to 500, and the convex projections generated as the return of the fine through-holes when the resin sheet is punched are made to face the mold cavity surface. The mold was clamped and molded. Further, in the third invention, in the first or second invention, before the mold is closed by sandwiching the resin sheet arranged on the mold cavity surface, the resin sheet is preliminarily set at a softening point temperature of the resin sheet. I tried to preheat to the neighborhood.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, in an injection molding machine, a resin sheet is arranged in advance on a mold cavity surface before injection filling of resin, and the mold is closed to inject and fill molten resin, or After injection filling, the mold surface temperature is heated to the softening point temperature of the resin sheet or higher, and then the mold is cooled and solidified and cooled to a temperature at which the mold can be taken out, and then the mold is opened and the molded product is taken out. Therefore, the resin sheet is melted in the cavity, and the back surface side of the resin sheet is in close contact with the resin injected in the same molten state,
On the surface side of the resin sheet, the mold cavity surface is also strongly transferred to a high level, and a smooth and beautiful molded product with high surface properties can be made. Further, by providing a fine through hole in the resin sheet, and by directing the return of the fine through hole toward the cavity surface side, the residual gas between the resin sheet and the resin is prevented, and the fine through hole is also blocked, No holes remain. Therefore, it is possible to obtain a bonded injection-molded article having high gloss and good surface transferability.

[0006]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1 to 4 relate to an embodiment of the present invention, FIG. 1 is an overall vertical cross-sectional view of an injection molding machine, FIG. 2 is a perspective view of the injection molding machine, and FIG. 3 is a cross-sectional view showing a surface state of a bonded injection-molded product. 4 and 5 are enlarged cross-sectional views of the resin sheet before and after the bonding. In FIGS. 1 and 2, a pair of left and right molds 8 and 8 (referred to as fixed mold 8A and movable mold 8B, respectively) are brought into contact with the side surfaces of the fixed platen 3 and the movable platen 4 of the injection molding machine 1, respectively. Both molds 8, which are arranged so that they can be separated from each other, are opened.
A roll 20 around which the resin sheet S is wound is arranged at a position where the space between the parts 8 is hung downward from the upper part via a roll base 22. A cutter 3 which is attached to a roll base 22 at the lower end of the roll 20 and which is horizontally moved toward and away from the fixed platen 3 by operating the air cylinder 30a is formed by a sharp blade.
0 is provided, and a cutter seat 30b is provided in the front of the cutter seat 30b having a groove in which the cutting edge of the cutter 30 is fitted, and the hanging resin sheet S is sandwiched between both molds 8 and 8 to close the mold. After that, it can be disconnected. Further, a sheet clip 24 for gripping the lower end of the resin sheet S and holding the resin sheet S in a vertically extended state during operation.
Is provided at the lower end of the mold 8.

On the other hand, in the portion of the mold 8 facing the cavity surface, a heat medium or a refrigerant body is switched and flowed, if necessary,
Medium passage 8 for heating or cooling the cavity surface of the mold 8.
a (not shown) in which a is disposed (heat medium or refrigerant body)
It is connected to the switching supply device. On the other hand, a plurality of vent holes 8b, which penetrate the die 8 from the cavity surface of the die 8 at right angles to the cavity surface and discharge air, are arranged at appropriate intervals. Then, in order to positively suck the air exhausted from the vent holes 8b, the collecting duct 10 is provided so as to cover the outside of the mold 8, and the exhaust pipe including the electromagnetic valve 12 and the suction fan 14 is provided. 11 is provided. Alternatively, the mold 8 may be made of a metal provided with countless fine air holes, that is, a porous metal, instead of the vent hole 8b.

The resin sheet S wound on the roll 20 is
Besides the same kind of resin as the molten resin P, a different kind of resin from the molten resin P can be used. The resin sheet S may be a multilayer resin sheet, a metal foil, paper, glass fiber or the like may be laminated between the sheets in a sandwich shape, or the sheet may be filled with an inorganic substance (glass fiber, inorganic mineral, etc.). . The thickness of the resin sheet S is not preferably too thick because it is necessary to manufacture a bonded injection molded product, and is usually 1 mm or less, but preferably 0.5 mm or less. If the resin sheet S is too thick, it is difficult to obtain a molded product that matches the cavity shape in the deep shape in which wrinkles easily occur. In addition, the cooling time after molding becomes long and the productivity is lowered. If it is too thin, the resin sheet S
May be damaged during molding. As shown in FIG. 2, on the surface of the resin sheet S, fine through holes h for discharging the air present between the molten resin P and the resin sheet S at the time of press-molding with the molten resin P are provided, as shown in FIG. A plurality of them are arranged in a lattice or zigzag pattern. The diameter of the fine through hole h is 0.1 mm
˜1 mm, preferably 0.1 mm or more and 0.3 mm or less, and the array density is preferably 10 or more and 500 or less per 100 cm ² . The reason is that if the diameter of the fine through holes h is 0.1 mm or less, it is difficult to discharge the gas, and if it is 0.3 mm or more, the traces of holes are likely to remain after molding, and if it is 1 mm or more, the traces of the holes are conspicuous. Lower limit of density (10 or more per 100 cm ² )
Is determined from the minimum required gas discharge area,
Upper limit of array density (500 or less per 100 cm ² )
Comes from the fact that the effect of gas discharge is the same even if more than this is provided. However, when the elongated ribbon-shaped resin sheet S is locally attached to the surface of the molded product, the fine through holes h may be omitted (the intervening air deviates from the left and right ends of the ribbon-shaped resin sheet S). Therefore, the fine through hole h is not required intentionally).

The injection pressure after the mold is closed completely eliminates the air between the surface of the molten resin P and the resin sheet S adhered to the surface of the molten resin P, and the air remains between the two so that the surface of the molded product is exposed. An appropriate pressure is selected as appropriate to prevent defects such as the formation of bubbles and to allow the resin flow and filling of the molded article body to be appropriate.

The heating temperature and the cooling temperature of the surface of the die 8 are properly selected according to the kind of resin on the surface of the resin sheet S which is in contact with the die. That is, the resin sheet S is usually produced by extrusion molding and has poor surface properties, and in order to improve the surface properties of the bonded injection-molded product of the present invention, that is, to improve the surface transferability of the molded product. ,
It is heated above the softening temperature of the resin, and after surface transfer is sufficiently performed, it is cooled immediately. However, when the molten resin material and the resin sheet material are different and the softening point temperature of the molten resin P is higher than the softening point temperature of the resin sheet S, it is not sufficient to raise the mold surface temperature to the resin sheet softening point temperature or higher. Therefore, high transfer and high quality molded products cannot be obtained. That is,
If the softening point temperature of the molten resin or resin sheet is different,
The mold surface must be heated to a temperature exceeding the higher softening point temperature of the two softening point temperatures. The softening point temperature of the resin is equal to the glass transition temperature in the case of the amorphous resin, 110 ° C to 130 ° C in the ABS resin, and about 120 ° C to 140 ° C in the modified PPO resin.

On the other hand, in the case of a crystalline resin, the temperature between the crystallization temperature and the melting point is suitable, 130 ° C. to 160 ° C. for PP and 100 ° C. to 1 ° C. for PE.
The temperature is 30 ° C and 180 ° C to 230 ° C for nylon 6. On the other hand, the cooling temperature is set to about 80 ° C. to 100 ° C., and after the temperature is lowered to this level, the mold is opened and the molded product is taken out. Various oils, water, and pressurized water (steam) are used as the heat medium and the cooling medium for heating or cooling the mold, and it is desirable to use the same substance having different temperatures.

The surface of the resin sheet S which comes into contact with the molten resin is coated with an adhesive in advance, or a sprayed adhesive solution is spray-coated.
Alternatively, it is desirable to consider brushing so as to facilitate the joining with the surface of the molten resin P during molding.

The operation of the bonded injection molding method of the present invention in the injection molding machine 1 configured as described above will be described. First, while holding both molds 8 and 8 in the mold open state, the resin sheet S is wound down from the roll 20 and hung down, and the lower end is pinched by the sheet clip 24, and held in the vertically stretched state. Then, the mold is closed (or an injection compression molding method of injecting with the mold slightly opened may be adopted),
The upper end of the resin sheet S is cut by the cutter 30. afterwards,
The nozzle 2a of the injection device 2 is brought into close contact with the injection port of the fixed board 3 and then injection filling is started. During this time, the molds 8 and 8 are heated to near the softening point temperature of either the resin sheet S or the molten resin P. When the molten resin P and the resin sheet S are both ABS resin, for example, 80
Raise the temperature to ℃. In this way, the molten resin P is inserted into the cavity with the resin sheet S sandwiched inside the cavity.
Is injected and filled to form a bonded injection-molded product. After the injection is completed, the heating medium is flown through the medium passage 8a in the mold closed state to raise the mold temperature to the softening point temperature of the resin or higher than the softening point temperature. In the case of ABS resin, the temperature is raised to 130 ° C., for example. Then, the pressure holding state is maintained for a certain period of time, and the pressure is gradually reduced. Next, the medium passage 8
A cooling medium is flown through a to cool the mold temperature to, for example, 80 ° C., and then the mold is opened and the molded product is taken out. In the molded product molded as described above, the surface of the resin sheet S is softened together with the molten resin P to be in a molten state, pressed against the mold cavity surface and the mold cavity surface is transferred, and the molten resin surface and the resin sheet back surface are transferred. Are crimped together and joined.

In the resin sheet S, when the fine through-holes h have no "return" at the time of punching, as shown in FIG. Traces remain, and there is a fear that the aesthetics will be impaired. In order to improve this problem, in the present invention, the resin sheet S has, for example, fine through holes h punched by a punching method such as a pressing method. As a result, as shown in FIG. 4, the convex protrusion 60 is formed in one of the minute through holes h. By making the surface on which the convex projection 60 is formed face the mold surface, and as described above, by interposing between the mold surface and the molten resin surface and clamping and holding pressure, Convex projection 60 of fine through hole h
As a result of being pressed and crushed and softened and melted, the fine through-holes are closed and the traces of the holes disappear.

The resin sheet S used in the laminated injection-molded product of the present invention may be a normal commercial product produced by extrusion molding, but a decorative pattern or a decorative pattern is applied to one side (the surface side of the molded product). By using, for example, an ABS extruded sheet on which a decorative pattern is printed, various molded products having high gloss and arbitrary colors and patterns can be obtained. Its applications include daily necessities (chairs, TV stands, bookshelves, cabinets, system kitchens, blackboards, sheds, desk tops, piling tops, furniture doors, side panels, bathtubs, mirror stands, etc.) Home appliances (refrigerator doors, dishwashers) Doors, washing machine doors, washing machine side panels, TVs, speaker boxes, computer housings, etc. Automotive products (spoilers, glove box doors, instrument panels, rear partial shelves, door trims, side garnishes, console boxes, road floors, bumpers, fenders) There are trunk lids, motorcycle fenders, outer panels, etc.) Building materials (doors, wall materials, partition boards, partitions, etc.) Daily miscellaneous goods.

Further, as shown in FIG. 3, by embedding a metal foil 40 or the like on the inner surface of the resin sheet S on the parison side,
By connecting electric wires to the floor panel that can be heated or the metal foil 40, the applications of automobile-related parts such as a spoiler with a built-in antenna, a glove box door, and interior parts will be expanded. Further, by combining known techniques such as insert and foam molding, the usage can be further expanded. Therefore,
As shown in FIG. 3, the surface of the molded product can be formed as a smooth surface without a step as shown in FIG. 3 without forming the step 50 as in the pasted molded product of the conventional method as shown in FIG. Also,
If the fine through holes h provided in the resin sheet S have a small diameter of 0.3 mm or less, after the air is exhausted by melting the sheet surface due to the heating of the mold, it is automatically removed from the surroundings. Since it is crushed and blocked, there is no problem that a large number of pores remain on the product surface and deteriorate the quality. However, as described above, the fine through-hole h is formed into the convex projection 60.
It is desirable that the punched hole with a hole be such that the hole trace disappears after the bonding.

[0017]

As described above, in the present invention,
In an injection molding machine that injection-fills and molds a resin, a resin sheet is placed in advance on the mold cavity surface before injection-filling the resin, and the mold is closed and injection-filled with the molten resin, or after injection-filling. After heating the mold surface temperature to the softening point temperature of the resin sheet or higher, the molded product is cooled and solidified and cooled to a temperature at which it can be taken out, and then the mold is opened to take out the molded product. By heating the back surface of the sheet above the softening point to improve the fusion property between the resin sheet and the surface of the molten resin, the gas can be easily discharged from the mold through the vent hole, so that it has a smooth surface without air traps. A molded product with high transfer and high surface properties can be obtained. Further, a resin sheet having 10 or more and 500 or less fine through holes each having a diameter of 0.1 mm to 1 mm formed by punching on the surface per 100 cm ² of area is provided on a mold cavity surface and a molten resin surface. By sandwiching the mold between the molds and molding, the back surface of the resin sheet is closely adhered to the molten resin, so the resin sheet is not damaged, and the inside of the mold cavity has a high-gloss surface that fits in a curved state. A bonded injection-molded article having excellent transferability can be obtained. Furthermore, by freely selecting the color of the resin sheet, it is possible to easily, easily, and inexpensively produce a multicolor, multi-layer molded product without changing the color with a single-layer injection molding machine. Also,
It is possible to enjoy a variety of designs and designs by adopting a resin sheet with decorative patterns and decorative patterns.

[Brief description of drawings]

FIG. 1 is an overall vertical sectional view of an injection molding machine according to an embodiment of the present invention.

FIG. 2 is a perspective view of an injection molding machine according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a surface state of a bonded injection-molded article according to an example of the present invention.

FIG. 4 is an enlarged cross-sectional view of a resin sheet before and after bonding in an injection molding method according to an embodiment of the present invention.

FIG. 5 is an enlarged cross-sectional view of a resin sheet before and after bonding showing a comparative example in the injection molding method according to the present invention.

FIG. 6 is an overall vertical sectional view of a conventional injection molding machine.

FIG. 7 is a cross-sectional view showing a surface state of a conventional bonded injection-molded article.

[Explanation of symbols]

 1 Injection Molding Machine 2 Injection Device 2a Nozzle 3 Fixed Plate 4 Movable Plate 8 Mold 8A Fixed Mold 8B Movable Mold 8a Medium Passage 8b Vent Hole 10 Collecting Duct 11 Exhaust Pipe 12 Solenoid Valve 14 Suction Fan 20 Roll 22 Roll Stand 24 Seat clip 30 Cutter 30a Air cylinder 30b Cutter seat 40 Metal foil 50 Step 60 Convex protrusion P Molten resin (base resin) S Resin sheet h Fine through hole

Claims (3)

[Claims] 1. A movable plate is arranged so as to be able to come in contact with and separate from a fixed plate, and a resin is introduced into a cavity formed by a pair of left and right molds attached to the fixed plate and the movable plate through an injection device. In an injection molding machine that performs injection filling and molding, a resin sheet is placed in advance on the mold cavity surface before resin injection filling, and the mold is closed and the molten resin is injection filled, or after injection filling Bonding injection characterized by heating the mold surface temperature to the softening point temperature of the resin sheet or higher, cooling the mold to a temperature that allows the molded product to cool and solidify, and then opening the mold to take out the molded product Molding method. ^2. Ten to 500 fine through holes having a diameter of 0.1 mm to 1 mm formed by punching on the surface of the resin sheet are arranged per 100 cm ^{2 of} area, and the fine through holes are formed at the time of punching the resin sheet. The convex projection generated as a return of the through hole is opposed to the mold cavity surface and clamped,
The laminated injection molding method according to claim 1, wherein the molding is performed. 3. The resin sheet according to claim 1, which is preheated to a temperature around the softening point of the resin sheet before closing the die with the resin sheet provided on the die cavity surface sandwiched therebetween. The laminated injection molding method described.