JPH0367845B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method of compressing a thermoplastic resin base in a compression die to form an oriented molded product. The object of the present invention is to improve a method for compression molding a thin oriented sheet of thermoplastic resin, and to provide a method for economically molding the oriented sheet. Conventionally, the method of forming oriented molded products by compression molding is to apply a mold release agent or lubricant in advance and layer them, then compress and orient them with a compression mold at a temperature above the glass transition temperature and below the melting point. A method of obtaining an oriented molded product is known (Japanese Patent Laid-Open No. 144728/1983).
issue). In the conventional method described above, the mold release agent or lubricant applied to the base material is intended to lubricate the base material between the compression molds and to facilitate peeling of the molded products from each other. If it is applied between each substrate, slippage will occur between the stacked substrates during compression molding, and each substrate will be stretched separately, making it impossible to plug each substrate uniformly, and the laminated state of the substrates will collapse. and the plug will not flow. Therefore, there is a problem that the orientation state varies among the substrates and that a good oriented molded product cannot be obtained. Furthermore, there are also problems in that it takes a lot of effort to uniformly apply a mold release agent or a lubricant in a sufficient amount, and it takes time and effort to remove it from a molded product after molding. The present invention is an improvement on the conventional compression orientation molding method described above, and produces a thin oriented sheet with a uniform orientation.
This makes it possible to manufacture multiple sheets at once with simple operations. That is, the present invention provides a method for forming an oriented molded product by compressing a thermoplastic resin base in a compression die, in which two or more layers of thermoplastic resin bases are stacked, and between each base, the base and Non-adhesive,
By placing a resin film or sheet whose viscosity during molding is 1/30 to 30 times the viscosity of the substrate, the substrates are made non-adhesive to each other, and the entire stacked substrate is vacuum-packed and placed in the die, and the die is The interface between the inner surface and the surface of the vacuum packaging body is lubricated, and the resin base is compressed at a temperature above the glass transition temperature and below the melting point to orient the resin base, and after cooling, it is taken out from the die and molded from each base. This is a compression molding method for oriented molded products in which two or more molded products are obtained by peeling oriented molded products from each other. In the present invention, the non-adhesive resin film or sheet that has a specific viscosity during molding not only facilitates the peeling of the molded product but also causes uniform plug flow on each stacked substrate during compression molding. If the viscosity of the non-adhesive resin film or sheet is too high or too low, the stretching stability of the base laminate will be impaired, making it impossible to obtain a uniform plug flow state. Also, the reason why a non-adhesive resin film or sheet is used instead of a mold release agent or lubricant is that it is difficult to obtain the above-mentioned viscosity, and it takes time and effort to uniformly apply a sufficient amount of mold release agent or lubricant. This eliminates the need to remove mold release agents and lubricants from molded products. The reason why the present invention attempts to obtain a plug-flow state is that the present invention is aimed at compression molding, which is completely different from the commonly used tension molding. That is, in tension molding, the orientation direction can be directly controlled by controlling the tension direction, but in compression molding, the orientation direction cannot be controlled by the compression direction, and as a result of compression, This is because the orientation direction cannot be controlled other than indirectly from the flow of the resulting substrate. In particular, in the present invention, the substrates are piled up and compression molded all at once. In this case, the compressive force is applied to the inner layer side of the base material laminate through the outer base material, and the stretching state is likely to be different from that of the outer base material to which the compressive force is directly applied. Therefore, in the present invention, the above-mentioned non-adhesive resin film or sheet with a specific viscosity is used to compress and stretch the substrate laminate as if it were a uniform, integrated object, thereby making it possible to uniformly plug each substrate. By allowing the material to flow, a molded product with uniform and good orientation can be obtained from each substrate. In addition, in the present invention, the base material layered with a non-adhesive film or sheet interposed is vacuum-packed and placed in the die to enable compression molding under deaerated conditions. This prevents air from being trapped between the stacked substrates during compression molding, thereby preventing air bubbles from forming on the molded product. In particular, when separately manufactured substrates are layered with non-adhesive films or sheets, air is likely to be trapped between the layers, and the vacuum packaging of the present invention is extremely effective in reducing the incidence of defective products. The thermoplastic resin mentioned in the present invention is generally a thermoplastic resin that can be compression molded, such as polystyrene, styrene-acrylonitrile copolymer,
Polyolefins such as ABS resin, polyvinyl chloride, polymethyl methacrylate, polycarbonate, polyester, nylon, polyphenylene ether, polyetherimide, polyoxymethylene, polyethylene, and polypropylene, various fluorocarbon resins, and blends and combinations of these resins. Polymers, etc. It is particularly suitable for molding acrylic resins mainly composed of methyl methacrylate (hereinafter abbreviated as MMA), polymethyl methacrylate (hereinafter abbreviated as PMMA), MMA and alkyl acrylate copolymer Co (MMA-AA)), MMA- Maleic anhydride-styrene terpolymer (Co(MMA-MAH)
-St)), MMA-methacrylamide copolymer (Co(MMA-MAAmide)), etc. can be used satisfactorily. Ultra-high molecular weight products of these acrylic resins and gelatinized products that have been slightly crosslinked can also be used satisfactorily. Ultra-high molecular weight MMA has excellent chemical resistance,
A good sheet can be obtained. Colorants, ultraviolet absorbers, infrared absorbers, heat ray reflectors, flame retardants, heat stabilizers, antistatic agents, and the like can be added to these thermoplastic resins as necessary. Acrylic resin has excellent weather resistance and transparency, and a thin 22-axis oriented sheet molded according to the present invention from an acrylic resin containing an ultraviolet absorber, an infrared absorber, a heat ray reflector, etc. can be favorably used as a component of a glazing agent. Furthermore, thermoplastic resins that can be favorably used in the present invention include resins that are difficult to mold due to their high viscosity, such as ultra-high molecular weight polymers, and polyphenylene, which is preferably molded with high viscosity because its softening temperature and decomposition temperature are close to each other. Ether, nylon 46 [−NH−(CH ₂ ) ₄ −
There are polyacetal resins such as NH-CO-( _CH2 ) ₄ -CO-] _o which are preferably stretched while crushing the formed spherulites in a high viscosity state because of their fast crystallization speed. The thermoplastic resin substrate mentioned in the present invention is a plate-shaped substrate made of the above thermoplastic resin with a thickness of 0.5 to 50 mm, preferably a plate-shaped substrate with a thickness of 1 to 20 mm. Laying two or more thermoplastic resin bases in a non-adhered state as described in the present invention means that the oriented molded products formed from each base material can be easily peeled off from each other after overlapping and compression molding. It should be kept in a bonded state. Easily peelable generally means 2Kg/25mm or less (200mm/min), that is, the peel strength when a 25mm wide molded product is pulled at a speed of 200mm/min is preferably 2Kg or less, and more preferably 1Kg. It is as follows. In order to place the substrates one on top of the other in a non-adhesive state, a non-adhesive resin film or sheet is placed between each substrate. In this case, the non-adhesive resin film or sheet is
During molding, it is preferable that the viscosity is close to that of the resin base, and the viscosity is in the range of 1/30 to 30 times. If the difference in viscosity between the resin base and the non-adhesive resin film or sheet is small, when the resin base is stretched during compression molding, the non-adhesive resin film or sheet will also be stably stretched, resulting in a uniformly oriented molded product. It will be done. The most preferred non-adhesive resin film or sheet is one that has a viscosity of 1 to 20 times the viscosity of the resin base upon molding and has a smooth surface. When a film or sheet having a higher viscosity than the resin base and a smooth surface is used, the surface of the film or sheet is transferred to the surface of the molded product, resulting in a molded product with a smooth surface. The thickness of the non-adhesive resin film or sheet must be such that it can be easily removed from the molded product after molding. The preferred thickness is 5 to 500 μm, more preferably 10 to 100 μm after orientation molding.
, and thicker than this is uneconomical.
If the thickness is less than this, peeling becomes difficult. When acrylic resin is used as the resin base, polyolefin, nylon, etc., which are non-adhesive to the acrylic resin and have a viscosity similar to the acrylic resin at the orientation molding temperature of 130 to 170°C, can be used. For example, polypropylene homopolymer , polypropylene copolymerized with a small amount of ethylene, nylon 11, nylon
12, nylon 6, etc. can be used satisfactorily. In order to lubricate the interface between the inner surface of the die and the surface of the vacuum packaged body made of vacuum-packed resin material, a lubricant is applied to the inner surface of the die, or a lubricant is applied to the interface between the inner surface of the die and the vacuum packaged body. A lubricated state can be achieved by providing a sheet into which a lubricant is mixed. The lubricant mentioned in the present invention is a fluid with a viscosity of 5000 poise or less, preferably 1000 poise or less during molding, such as liquid paraffin, various silicone oils such as polydimethylsiloxane, stearic acid, stearic acid metal salts, etc. In addition to various fatty acids and their metal salts, various surfactants, glycerin, polyethylene glycol, low molecular weight polyethylene, mixtures of these fluids, commonly used lubricants can be used. Orientation by compression at a temperature above the glass transition temperature and below the melting point of the resin substrate can be achieved by uniformly plug-flowing the stacked substrates in a die due to compressive force. Uniform plug flow molding can be achieved by keeping the interface between the inner surface of the die and the surface of the vacuum package well lubricated. In the present invention, uniaxial orientation, 2
Although any type of axial orientation can be performed, this method is especially suitable for biaxially oriented molding.
An axially oriented sheet can be formed well. In the present invention, the stretching ratio can be selected as required, but is preferably 2 to 10 times, more preferably 3 to 7 times in terms of area ratio. Particularly, what can be well molded in the present invention is PMMA having a weight average molecular weight of 1 million or more, or an ultra-high molecular weight biaxially stretched thin sheet mainly composed of MMA. The performance of ultra-high molecular weight PMMA is particularly markedly improved by biaxial stretching, that is, impact resistance and chemical resistance are significantly improved. The present invention will be explained with reference to the drawings. FIG. 1 shows the process of forming a biaxially oriented sheet by compression molding. FIG. 2 shows the relationship between the thickness of the biaxially oriented sheet and the necessary compressive force when Co (MMA-AA) is made into a biaxially oriented sheet by the method shown in FIG. FIG. 3 shows the process of molding a biaxially oriented sheet by the compression molding method of the present invention. FIG. 4 shows various methods of placing the four layers of resin substrates of the present invention on top of each other in a non-adhered state. In Fig. 1, a lubricant is applied to the inner surface 2 of the compression die 1, and a plate-shaped substrate 3 of thermoplastic resin is placed (1
-1) The substrate 3 is heated to a temperature above the glass transition temperature and below the melting point, and then compressed to cause the substrate 3 to plug flow and become biaxially oriented (1-2), and then cooled as it is to form the biaxially oriented sheet 4. obtain. The compressive force required to form the biaxially oriented sheet 4 varies depending on the type of resin, stretching temperature, stretching ratio, thickness of the biaxially oriented sheet, etc. Figure 2 shows the relationship between the thickness of the biaxially oriented sheet and the required compressive force when Co (MMA-AA) containing 5% by weight of methyl acrylate is stretched at 140°C to 5 times the area ratio using the method shown in Figure 1. This is what is shown. The thinner the biaxially oriented sheet, the higher the compressive force required. The manufacturing cost of a compression molding device increases in proportion to the compression force, and therefore, the thinner the sheet, the higher the molding cost. The present invention provides an improved method for forming thin sheets that are expensive to form.
Furthermore, as shown in FIG. 1, the method that previously allowed molding of only one sheet at a time is now capable of molding two or more sheets at a time, thereby improving productivity. FIG. 3 explains the invention. After applying a lubricant to the inner surface 6 of the compression die 5, a non-adhesive film 8 is placed on each interface between the four thermoplastic resin bases 7, and the entire stacked base is covered with a non-adhesive resin film. 14, and placed in a compression die (3-1). Above the glass transition temperature of substrate 7,
After heating to below the melting point, the material 7 is compressed and plug-flowed to form four biaxially oriented sheets 9 (3-2), which are then cooled and vacuum packaged into four biaxially oriented sheets. 9 from the compression die 5 (3-3), then the non-adhesive resin film 14 is removed, each biaxially oriented sheet is peeled off, and the non-adhesive film is further peeled off from the oriented sheet to form a thin biaxially oriented sheet. Obtain an oriented sheet 10 (3-4). Also,
In the present invention, by transporting and storing the non-adhesive resin film 14 before removing it, and peeling off each sheet as necessary, it is possible to reduce the effort and staining of the sheets during loading. FIG. 4 shows various methods for placing two or more layers of thermoplastic resin substrates on top of each other in a non-adhesive manner. (4-1) is a method of placing a non-adhesive resin film 13 on each interface and surface of the resin base 11;
(4-2) are two types of resins 15 that are non-adhesive to each other,
16, (4-3) shows the case where the resin base has three layers consisting of the surface layer 17 and the inner core 18, and a three-layer biaxially oriented sheet is molded, and the three-layer resin This is a method in which two substrates are stacked and a non-adhesive film 19 is placed on the interface and both surfaces.
In the present invention, by vacuum packaging the resin base,
It is possible to prevent air from remaining at the overlapped interface and deteriorating the surface of the molded product. If a resin base with a mirror-like smooth surface is used, a non-adhesive resin film or sheet with a mirror-like smooth surface is vacuum packaged as shown in , and then compression molded and biaxially oriented, biaxially oriented molding with a smooth surface is obtained. Goods can be obtained. The film or sheet to be vacuum packed may be the same as or different from the film or sheet placed on each resin substrate interface. For stable plug flow compression molding, it is preferable to use a sheet on the outermost surface that has good slippage with the inner surface of the die. The present invention is a compression molding method particularly suitable for molding thin biaxially stretched sheets, and the molding method of the present invention
Thin biaxially stretched sheets with a thickness of about 10 μm to 1 mm can be formed well. It is inefficient to mold thin biaxially stretched sheets one by one by compression molding, but in the present invention, two or more sheets, and if necessary, ten or more sheets can be stacked and molded. According to the present invention, thin sheets of biaxially stretched sheets made of ultra-high molecular weight polymers, resins with high softening temperatures, easily thermally decomposable gun resins, etc., which are generally difficult to mold, can be molded well. By the molding method of the present invention, it is possible to mold thin oriented sheets, which have been difficult to mold in the past, and a plurality of oriented sheets can be molded by one compression molding, which has a large economic effect. By the molding method of the present invention, thin oriented sheets of various thermoplastic resins can be economically molded. Can be used for face plates, name plates for various office equipment, name plates for automobiles, parts for various glazing agents, etc. Example 1 A 4 mm thick ultra-high molecular weight PMMA sheet with a smooth surface and a weight average molecular weight of 1.5 million, polymerized by the cell cast method, was used as a resin base, five sheets of the base were stacked, and a 100 μm thick mirror-like sheet of polypropylene was placed at the interface of each base. The 6-ply thick-walled base material was vacuum-packed with the above-mentioned polypropylene sheet to obtain a base material for compression biaxial orientation molding. As shown in FIG. 3, polydimethylsiloxane was applied to the inner surface of the compression die, and the compression die and resin base were heated to 150° C. and compressed to cause plug flow, resulting in biaxial orientation with an area ratio of 4 times. After cooling the compression die and cooling the biaxially oriented molded product,
The molded products were taken out from the compression die, each molded product was peeled off from each other, and the polypropylene was further peeled off to obtain five 1 mm thick PMMA biaxially oriented sheets with smooth surfaces. The compression force required for the above compression molding was 90 Kg/cm ² per biaxially oriented sheet. The tensile properties of a 1 mm thick PMMA biaxially oriented sheet and a non-oriented PMMA sheet molded by the molding method of the present invention were as follows.

[Table] The biaxially oriented sheet molded according to the present invention had high elongation and excellent toughness. Comparative Example 1 The 4 mm thick PMMA sheet used in Example 1 was used as a base material, and biaxially oriented molding was performed by the compression molding method shown in FIG. Biaxially oriented 4 times the area ratio, 1
Two biaxially oriented sheets were obtained. The compression force required for compression molding was 240 Kg/cm ² per biaxially oriented sheet. Example 2 Molding was carried out in the same manner as in Example 1 using the following resins and films at the following molding temperatures.

[Table] For each resin, five biaxially oriented sheets with a smooth surface and a thickness of 1 mm were obtained in one molding process. Example 3 Methyl acrylate 5% by weight Co(MMA-
A 2 mm thick sheet with a smooth surface of AA) was used as a resin base, 10 sheets were stacked and molded at 140°C in the same manner as in Example 1, and a 0.5 mm thick biaxially oriented sheet with a smooth surface was made.
Ten pieces were obtained by one compression molding. Example 4 A 2 mm thick sheet with a smooth surface of PMMA polymerized by the cell cast method and a 2 mm thick sheet with a smooth surface of bisphevanol polycarbonate (PC) were prepared.
PMMA/PC/PMMA were stacked to form one set of resin substrates, two sets of the substrates were stacked together, and a 100 μm thick mirror film of nylon 12 was placed on the interface. PMMA/PC/PMMA/Nylon12/
After vacuum-packaging the PMMA/PC/PMMA laminate with a 100 μm thick nylon 12 film, it is processed using a compression die coated with polydimethylsiloxane.
It was compressed at 170°C and biaxially oriented with an area ratio of 4 times. After cooling, the biaxially oriented molded product is removed from the die, the molded product is peeled off, and the nylon 12 film is removed.
Two 1.5-thick biaxially stretched sheets with smooth surfaces were obtained with three layers of PMMA/PC/PMMA. Example 5 Five 2 mm thick sheets of polyetherimide (ULTEM1000 manufactured by General Electric Company) were stacked together as a resin base, and each interface and both surfaces of the base were coated with polyurethane.
- Place a 100 μm thick sheet of methylpentene-1,
Furthermore, the whole is made of poly 4-methylpentene-1.
It was vacuum packed with a 100 μm thick sheet and used as a base material for compression biaxial orientation molding. The substrate was heated to 230℃ 2
The material was heated by sandwiching it between two iron plates for 5 minutes and 15 minutes, and the material was compressed with a lubricated die heated to 230.degree. C., resulting in biaxial orientation with an area ratio of 4 times. The die was cooled to cool and take out the oriented molded products, and each molded product was peeled off to obtain five biaxially oriented sheets of polyetherimide having a thickness of 0.5 mm. Example 6 A 2 mm thick sheet of hard polyvinyl chloride (Sunroid Plate manufactured by Tsutsunaka Plastic Industries Co., Ltd.) was used as a resin base, five sheets of the base were stacked, and a 100 μm thick sheet of high density polyethylene was placed at the interface of each base. ,
Furthermore, the whole was vacuum-packed with a 100 μm thick sheet of high-density polyethylene to form a base material for compression molding. Using the base material, molding was carried out in the same manner as in Example 1, and 0.5 mm
Five biaxially oriented hard polyvinyl chloride sheets with good thickness were obtained.

[Brief explanation of drawings]

Figure 1 is a schematic explanatory diagram showing the process of forming a biaxially oriented sheet by compression molding, and Figure 2 is a Co (MMA
-AA) is made into a biaxially oriented sheet by the method shown in Figure 1. A graph showing the relationship between the thickness of the biaxially oriented sheet and the necessary compressive force.
A schematic explanatory diagram showing the process of forming an axially oriented sheet,
FIG. 4 is a schematic cross-sectional view showing various methods of stacking four layers of resin substrates of the present invention in a non-adhered state.

Claims (1)

[Scope of Claims] 1. In a method for forming an oriented molded product by compressing a thermoplastic resin base material in a compression die, two or more layers of thermoplastic resin base materials are stacked, and a base material is placed between each base material. By placing a non-adhesive resin film or sheet whose viscosity during molding is 1/30 to 30 times the viscosity of the substrate, the substrates are made non-adhesive to each other, and the entire stacked substrate is vacuum-packed. placed in a die, lubricated the interface between the inner surface of the die and the surface of the vacuum package, compressed at a temperature above the glass transition temperature and below the melting point of the resin base to orient the resin base, and after cooling, taken out from the die; A compression molding method for an oriented molded product, which comprises peeling off oriented molded products formed from each base material to obtain two or more molded products.