JPS6337910A - Composite injection molding method - Google Patents

Abstract

PURPOSE:To easily manufacture a composite molded item, the shape of which is complicated and the ordinary thermoplastic resin surface of which is strongly bonded so as to be covered with a thermosetting resin layer by a method wherein molten thermoplastic resin is filled in a mold by injection under the state that thermosetting resin in uncured state is allowed to be present at the desired position in the mold of an injection molder. CONSTITUTION:When the molding of, for example, a square-dish-shaped lens for automobile fog lamp is intended, polyimide film is used as releasing film A and diallyl phthalate (DAP) resin as thermosetting resin. After the DAP resin is applied in 0.03mm thickness onto the polyimide film, it is left in room temperature and air-dried, the resultant film is fixed to the pins 11 of a mold and the mold is closed. Under the above-mentioned state, acrylonitrile-styrene copolymer is employed as the thermoplastic resin, and injected in the mold under the condition that the resin temperature is 240 deg.C. Next, high frequency current of 7kHz and 20kW is intermittently applied to coils 3 at intervals of 15sec so as to keep the temperatures of a cavity plate 1 and of a core plate 2 at 150 deg.C for 2min in order to completely cure the PAD resin. After being cooled and solidified through the circulation of cooling water in the mold, a composite molded item is obtained by being removed from the mold and peeling off the releasing film.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for manufacturing a composite molded article of a thermosetting resin and a thermoplastic resin, and more specifically, the present invention relates to a method for manufacturing a composite molded article of a thermosetting resin and a thermoplastic resin. The present invention relates to a composite injection molding method for easily producing a composite molded product in which cured resin layers are firmly bonded together by injection molding.

[Conventional technology]

Traditionally, thermoplastic resins have been widely used in various fields due to their good moldability, but their range of use has been limited due to their lack of surface hardness, heat resistance, flame resistance, chemical resistance, abrasion resistance, etc. This was an obstacle to expansion. On the other hand, although thermosetting resins are superior to thermoplastic resins in the above-mentioned properties, they are poor in moldability and formability.

It is desired to obtain a molded product that takes advantage of each other's strengths by integrating these two resins into one composite.

As composite molded products of thermosetting resin and thermoplastic resin, films of diallyl phthalate resin (hereinafter abbreviated as DAP) are used to improve the surface decoration and scratch resistance of some thermoplastic resin furniture. Products that are bonded with adhesive to the surface of thermoplastic resin molded products, or uncured thermosetting resins on the surface of some highly heat-resistant thermoplastic resins, such as glass fiber-reinforced polyamide resin molded products. Molded products coated with a so-called baking coating, which is applied and cured by heating, are known. The molding method is described in Japanese Patent Application Laid-Open No. 123463/1982, and although the object and structure of the invention is slightly different, an approximate technique is described in Japanese Patent Publication No. 43
-2577 publication etc. are known.

[Problem that the invention seeks to solve]

However, with the exception of a few examples such as the use of special highly heat-resistant thermoplastic resins mentioned above, there are also some methods of applying and baking thermosetting resins to ordinary thermoplastic resin molded products, but this is not normal. Due to their nature, thermoplastic resins tend to soften and deform when exposed to heat, and often fail to achieve their intended purpose.Additionally, the time-consuming process of painting is also a difficult point in production.

With the method of bonding thermosetting resin plates as described above, only a simple shaped molded product can be obtained with the thermosetting resin layer attached only to the flat surface of the molded product, and the thermosetting resin layer is attached to the surface. It is not possible to obtain a composite molded product having a complicated shape, such as a three-dimensional curved surface that is combined with loose parts.

Therefore, it is an object of the present invention to provide a method for easily manufacturing, by injection molding, a complex-shaped composite molded product in which the surface of an ordinary thermoplastic resin having a normal level of heat resistance is tightly coated and bonded with a thermosetting resin layer. The purpose is to provide a method.

However, it has been found that the specific manufacturing method is a very difficult problem.

One problem is the adhesion between the thermosetting resin and the thermoplastic resin. Even if a cured thermoplastic resin is pasted inside a mold and the thermoplastic resin is injection molded in the same manner as decorative molding, since the two resins originally have different properties, they have no affinity for each other and will not work together. It is essential to prevent the resin from peeling off from the contact surface. Also, even if the adhesive on the contact surface is devised,
It is by no means easy to provide adhesion strength that is practically sufficient.

The adhesion between the laminated thermosetting resin layer and the base thermoplastic resin is
The laminated layer on the surface of the molded product is cross-cut into 100 square sections of 1 ms + square, a Sellotape peel test is performed, and the adhesion is evaluated by the number of squares that are peeled off.

When a hardened thermosetting resin is installed in a mold, a thermoplastic resin is press-fitted into the mold, and the resin temperature and resin pressure bring them into close contact, depending on the combination of resins, it may appear that they are in close contact. However, when the above cellophane tape peeling test was performed, 1
Peel 100 out of 00 squares. That is, the result is 100
/100 peeling.

Furthermore, even if you attempt to cure a thermosetting resin by using the resin temperature during injection molding of a thermoplastic resin, it has been found that the uncured thermosetting resin cannot be cured at the normal injection temperature and time of thermoplastic resin. It is difficult to completely cure the thermosetting resin, leaving uncured areas, making it difficult to provide the surface of the composite molded product with the performance inherent to the thermosetting resin.

Furthermore, it is possible to heat the mold after injection of the thermoplastic resin to complete the curing of the thermosetting resin. Completely harden the thermosetting resin by switching between water and using a cartridge heater, and
In order to cool and solidify thermoplastic resin to obtain the desired molded product, heating and cooling a lump of iron such as an injection mold requires a cycle of at least 20 to 30 minutes, making it difficult to use normal heating methods. Even if it is used, it has no industrial value due to its poor productivity and expensive molds.

Therefore, the present inventors succeeded in efficiently heating and cooling only the forming surface of the mold by high-frequency induction heating, shortening the heating and cooling cycle, and succeeded in heating and cooling the thermosetting resin. exists in the mold of an injection molding machine in an uncured state, and injects and fills the molten thermoplastic resin, and then completes the curing of the thermoplastic resin by heating the mold using high-frequency induction heating. Then, by cooling the mold and releasing the composite molded product, it was possible to produce a composite molded product in which both resins were firmly bonded at the contact surfaces, and the present invention was completed.

[Means for solving problems]

That is, in the present invention, a molten thermoplastic resin is injected and filled into a welding mold with an uncured thermosetting resin present at a desired position in the mold of an injection molding machine, and then a thermosetting resin is injected into the welding mold. The present invention relates to a composite injection molding method characterized by cooling and releasing the mold after completing curing of the resin.

When an uncured thermosetting resin is combined with a thermoplastic resin in a mold as in the present invention, the uncured thermosetting resin is finely deformed during the combination, and the bonding area increases, although the reason is not clear.
A part of the uncured thermosetting resin and a part of its solvent migrate to the thermoplastic resin, improving the affinity of the contact surface.The thermosetting resin and the thermoplastic resin are combined into one. turned into
It is believed that a composite molded product with good adhesion on the contact surfaces can be obtained.

The present invention will be specifically explained below.

When manufacturing the composite molded product of the present invention, first, an uncured thermosetting resin is placed at a desired position in the shaping section of the mold of an injection molding machine, that is, the so-called cavity section and core section. To do this, apply a thermosetting resin solution to the desired position or paste a sheet-like prepolymer composition of a thermosetting resin,
Next, if necessary, the mold is rapidly heated to make the thermosetting resin solution or the composition into a viscous state.Next, the thermoplastic resin is injected into the mold and both resins are brought into contact. , unify. Thereafter, the mold is heated again to completely harden the thermosetting resin. Cooling water is then passed through the mold, the thermoplastic resin is also cooled and solidified, and the mold is released, thereby obtaining the desired molded product.

The above-mentioned state in which the thermosetting resin is viscous means that the monomer or prepolymer of the thermosetting resin, a mixture of the two, or a mixture of them dissolved or diluted in a solvent is mixed with a catalyst, a mold release agent, and as necessary. Add reinforcing agents such as glass fiber, viscosity modifiers, etc. to the inside of the mold, or paste it as a sheet.
When thermoplastic resin is injected, due to the flow resistance of thermosetting resin, the viscosity is such that the coating film and pasting do not cause the sheet to shift or cause significant unevenness in thickness, so the coating film thickness and resin solution composition must be carefully adjusted. If the viscosity can be adjusted to an appropriate value by adjusting the viscosity, that method may be used. However, a simpler method for adjusting the viscosity is to use a thermosetting resin solution or the sheet-like prepolymer composition attached to a mold. Before injecting the thermoplastic resin, an effective method is to preheat it to volatilize the solvent or slightly polymerize the thermosetting resin to make it viscous.

The thermosetting resin used in the present invention is a general term for resins that crosslink and harden when heated to a sufficiently high temperature.

Crosslinking includes those that occur naturally and those that contain a curing agent or catalyst for crosslinking, whether it is a resin that is usually called a thermoplastic resin or one that is crosslinked with a catalyst such as peroxide. , included in the present invention.

Examples of thermosetting resins suitable for the present invention include DAP resins, unsaturated polyester resins, epoxy resins, thermosetting polyurethanes, etc. These resins may be treated with catalysts, thickeners, glass fibers, etc., if necessary. It may also contain reinforcing agents such as mica and calcium carbonate, fillers, glass mats to enhance the reinforcing effect and shape retention effect in the mold, non-woven fabrics of various fibers such as Japanese paper, vinylon, polyester, etc. A thermoplastic resin film such as ABS resin containing a crosslinking agent such as divinylbenzene may also be used.

The thermoplastic resin of the present invention includes olefin resins such as polyethylene and polypropylene, styrene resins such as polystyrene, styrene-acrylonitrile copolymer, ABS resin, styrene-maleic anhydride copolymer, polyvinyl chloride, and vinyl chloride. - Vinyl chloride resins such as vinyl chloride copolymer (EVA), polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polycarbonate resins, polyamide resins, polyphenylene ether resins, polyoxymethylene resins, and polymethyl methacrylate resins These include so-called super engineering resins such as resins, polyetherimide resins, and polyphenylene sulfide resins, cellulose derivative resins such as cellulose acetate, and blends thereof. It may also contain conventional resin additives such as fillers and plasticizers.

An example of an injection mold used in the present invention is shown in FIG.

Fig. 1 shows an example of a three-plate type mold, in which a fixed side mold plate 5 is provided with a cavity plate 1 that forms a cavity, and a mold release film A and a thermosetting resin prepolymer sheet B are applied to this as necessary. If you use it, install pin 1) to fix it. In cases where a release film is not required,
When applying thermosetting resin directly to the mold, use pin 1)
The movable side mold plate 6 is also provided with a core plate 2 that forms a core in the same way. In order to heat the cavity plate and the core plate, a coil 3 made of a spirally wound steel pipe is arranged on the back side of each plate, and a high frequency current is passed through the coil to heat the cavity plate and the core plate by high frequency induction. Providing cooling water holes in the cavity plate and core plate is effective in shortening the molding cycle.

Furthermore, it is also possible to provide a sealing layer 4 of non-magnetic material such as copper or brass on parts of the matrix parts such as the fixed side template 5 and the movable side template 6 that do not need to be heated by high-frequency induction heating. This is effective in shortening the molding cycle.

It is convenient to use a high frequency power source of about 1 to 1000 KH2.

The release film is a synthetic resin film, such as polyolefins such as polyethylene and polypropylene, polycarbonate, polyamide, polyvinyl fluoride, polyester,
0 with films such as polyimide (for example, product name Kapton)
．． A value of approximately 01 to 1.0 Im- is convenient. or,
A mold release agent such as silicone or epoxidized soybean oil may be applied to the mold without using a mold release film.

(Example) Next, examples will be shown.

Example 1 An automobile fog lamp lens having a substantially rectangular and dish-shaped cross-sectional shape as shown in Fig. 1 was molded. A polyimide film was used as the release film A in Fig. 1, and DAP resin was used as the thermosetting resin.The composition of the DAP resin is a DAP prepolymer (
2-20mer), 6 parts of DAP%, and 3 parts of benzoyl peroxide were dissolved in 100 parts of acetone, and this was applied to a polyimide film to a theoretical thickness of 0.03 m, and left at room temperature for 1 hour. After leaving to air dry, the film was fixed to the pin 1) of the mold, the mold was closed, and As was used as the thermoplastic resin.
Using resin (acrylonitrile-styrene copolymer),
The resin was injected into the mold at a temperature of 240°C, and then a high frequency current of 7 KHz and 20 - was intermittently passed through the coil 3 at 15 second intervals to reduce the temperature of the cavity plate and core plate to 1.
Hold at 50°C for 2 minutes to completely cure the DAP resin,
Thereafter, cooling water was passed through the mold to cool and solidify the composite resin, which was then released from the mold and the release film was peeled off to obtain the desired composite molded product.

In this case, cavity plate 1 is used to harden the DAP resin.
Although it is sufficient to heat only the molded product, in order to prevent the molded product from warping, it is effective to heat the core plate 2 to approximately the same temperature and cool the cavity plate and the core plate at the same time.

As a result of observing the cross section of this composite molded product with a microscope, the gate part is slightly thin at o and ooa-1, but the other parts are almost 0.
．． It was confirmed that DAP resin layers of 0.010 to 0.01h+- were laminated.

Further, the adhesion of the DAP resin was tested by cross-cut cellophane tape peeling test, and the result was 0/100, with no peeling at all, and sufficient adhesion was obtained. Further, the surface hardness of the DAP resin layer is 3 to 4H in pencil hardness, which is significantly improved compared to the surface hardness F-H of the AS resin part.

Compared to conventional fog lamp lenses that use glass, the composite resin molded lens of this example is lighter, has better impact resistance from flying stones, etc., and above all, has improved design freedom and productivity. The benefits are immeasurable.

Example 2 An automobile headlamp lens that was slightly larger than Example 1 but had a similar shape was created. A DAP-impregnated sheet was used as the thermosetting resin. The DAP is made by adding 80 parts of DAP prepolymer, 3 parts of DAP nitrate, 5 parts of benzoyl peroxide, and 2 parts of unsaturated polyester to a vinylon nonwoven fabric.
A solution obtained by dissolving and impregnating 0 parts in 100 parts of acetone was used. The thermoplastic resin has a heat distortion temperature (HDT) of 1
) Glutaric anhydride copolymerization heat-resistant acrylic-styrene resin at 5°C (The manufacturing method for this resin is described in Japanese Patent Application Laid-Open No. 60-12070.
(Details in Publication No. 7) were used.

First, release polyimide film and 0.05m-thick DAP
The impregnated sheet was fixed in the cavity with stacking pins 1), the mold was closed, and the heat-resistant acrylic-styrene resin was injected into the mold at a resin temperature of 250°C. Therefore, by filling with this resin, the polyimide film and DAP-impregnated sheet are shaped into a cavity shape.

Next, a high-frequency current was applied to the coil, and the cavity plate and core plate were held at 150°C for 2 minutes to completely cure the DAP resin, and then cooled and released from the mold to obtain the desired composite resin headlamp lens. .

This headlamp lens has almost no uneven thickness, 0.15
It was a composite resin helamp lens having a uniform AP resin layer of mm thickness.

This lens did not peel off at all in the results of the adhesion cellophane tape peeling test, and its surface hardness was 3 to 4H, indicating that it was sufficiently durable for practical use.

In addition, since the molded product of the present invention is composited with DAP, the practical heat deformation temperature is 5.
It was also found that the temperature was improved by ~10°C.

Example 3 A roughly circular cosmetic compact case with a diameter of 10 cm+ and a gentle roundness was created. The compact is made of unsaturated paper with various patterns printed on it for the purpose of making it decorative and having a hard surface so that it will not be scratched even when rubbed against metal parts such as brooches and earrings in the handbag during use. A paper impregnated with polyester resin was used, and the impregnated paper was laminated to about 9c+* in the center of the surface to form a laminated composite, and ABS resin was used as the base resin.

The mold was made in the same manner as in Example 1, with fine vacuum holes in the core and a center direct gate for embedding the coil.

The mold was sprayed with a conventional mold release agent, and the unsaturated polyester resin-impregnated paper was attached to the core plate mold by vacuum suction.

The unsaturated polyester resin is made by adding a small amount of styrene mono, zinc stearate, and a peroxide catalyst to the isophthalic acid type unsaturated polyester resin used in ordinary BMC and the like.

After attaching this impregnated paper to the mold, ABS resin is injected into the mold at a resin temperature of 240°C, then a high frequency current is passed through the coil, and the mold is held at 160°C for 90 seconds to harden the unsaturated polyester resin. After that, the mold was cooled and released to obtain a compact case with the desired surface hardness and excellent decorative properties.

The hardness of the surface of this compact case is 3H on the pencil hardness scale.
This is much better than the hardness B of the base material ABS resin. In addition, the cross-cut cellotape peel test results were also 0/
At 100, the adhesion strength was also good.

〔Effect of the invention〕

According to the method of the present invention, combinations that were previously impossible to combine due to the relationship between the curing temperature conditions of the thermosetting resin and the heat deformation resistance temperature of the thermoplastic resin can now be combined and completely cured. A composite molded article is obtained in which the thermosetting resin and thermoplastic resin are firmly bonded. As a result, a molded article can be obtained that has excellent properties such as surface hardness, heat resistance, flame resistance, chemical resistance, abrasion resistance, and weather resistance that would be unimaginable with thermoplastic resin alone.

Furthermore, according to the method of the present invention, composite molded products with complex surface shapes can also be easily obtained. Furthermore, molded products having the above-mentioned properties imparted only to a portion of the surface can be easily obtained and are economical.

In addition, if only the forming surface of the mold is heated by high frequency induction, heating and
The cooling cycle is short, temperature control is easy, and the degree of curing of the thermosetting resin on the composite surface is also easy to control.

[Brief explanation of the drawing]

FIG. 1 is an example of a schematic conceptual diagram of a sectional view of a composite injection mold used in the present invention. A... Release film B... Uncured thermosetting resin 1... Cavity plate 2... Core plate 3... Coil 4... High frequency seal layer 5... Fixed side template 6...Movable side template plate 7...Mounting plate

Claims (6)

[Claims] (1) With the uncured thermosetting resin present in a desired position in the mold of an injection molding machine, molten thermoplastic resin is injected and filled into the mold, and then the thermosetting resin is cured. A composite injection molding method characterized by cooling and releasing the mold after completing the process. (2) The uncured thermosetting resin present in the mold is
It is applied in liquid form or affixed in sheet form to the forming surface of the mold,
Claim 1, wherein the injection filling of the molten thermoplastic resin is performed in a semi-cured state that has been cured to the extent that the shape at the time of application or attachment is maintained even after injection of the thermoplastic resin.
The method described in section. (3) The method according to claim 2, wherein the uncured thermosetting resin is cured by high-frequency induction heating of the shaping surface of the mold. (4) The method according to claim 1, wherein the curing of the thermosetting resin after injection and filling of the thermoplastic resin is completed by high-frequency induction heating of the shaping surface of the mold. (5) The method according to claim 1, wherein the uncured thermosetting resin is a thermosetting resin prepolymer, a mixture of a prepolymer and a monomer, or a mixture of these and a solvent. (6) Claims in which a thermosetting resin prepolymer, a mixture of a prepolymer and a monomer, or a mixture of them and a solvent contains a reinforcing material or is impregnated into a reinforcing material sheet. The method described in Section 5.