JP2727303B2 - Molding method for synthetic resin molded products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for molding a synthetic resin. More specifically, the present invention relates to a synthetic resin molding method such as an injection molding method, a blow molding method, a compression molding method, a vacuum molding method, an extrusion molding method, etc., which can withstand molding for tens of thousands of times using a mold coated with a heat insulating layer.

[0002]

2. Description of the Related Art In order to improve the reproducibility of imparting the shape state of the mold surface to a molded article by injecting a thermoplastic resin into a mold cavity and to improve the gloss of the molded article, it is usually necessary to use a resin temperature. It can be achieved to some extent by selecting molding conditions such as increasing the injection pressure and increasing the injection pressure.

[0003] Among these factors, the mold temperature has the greatest effect, and it is preferable to increase the mold temperature.
However, when the mold temperature is increased, the cooling time required for cooling and solidifying the plasticized resin is prolonged and the molding efficiency is reduced, so that the reproducibility of the mold surface is improved without increasing the mold temperature, and There is a demand for a method in which the required cooling time is not prolonged even when the mold temperature is increased. There is also a method in which holes for heating and cooling are provided in the mold, and heating and cooling of the mold are repeated by alternately flowing a heat medium and a coolant, but this method also consumes a large amount of heat. , The cooling time becomes longer.

[0004] On the other hand, a method of improving the mold surface reproducibility by coating the mold wall surface forming the mold cavity with a substance having a small thermal conductivity, that is, a heat insulating layer, is disclosed in WO93 / 93.
06980 and the like. Among them, it is shown that if a tough heat-resistant polymer having a large adhesion to a main mold and a large elongation at break is selected as a heat insulating layer, it can withstand tens of thousands of moldings. However, there are problems such as peeling depending on the shape of the mold and the thickness of the heat insulating layer. Furthermore, US
P3,734,449 shows a mold in which a metal mold wall surface is coated with a heat insulating layer, and the heat insulating layer surface is further coated with a thin metal layer. However, there is a problem that separation between the thin metal layer and the heat insulating layer occurs during molding.

[0005]

In recent years, there has been an increasing demand for omitting post-processing such as painting of injection molded products and blow molded products. There is an extremely strong desire to eliminate painting in order to reduce manufacturing costs during molding and reduce environmental destruction due to evaporation of solvents during painting. There is an extremely strong demand for the subsequent omission of the housing of electric and electronic equipment. In general, these housings have a complicated shape, and many molded products have a shape having a substantially right-angled corner. Also,
Due to its complicated shape, it is molded by injection molding of a multipoint gate. For this reason, a large number of weld lines are generated in the molded product, and a paint finish has been required to eliminate the unsightly weld lines. Many attempts have been made to obtain molded articles that can be used practically without painting.

We have studied various methods for covering the mold wall surface constituting the mold cavity with a heat insulating layer, improving the reproducibility of the mold surface, and reducing the conspicuous weld line. As a result, it was found that it is very effective to uniformly coat the heat-insulating layer made of a heat-resistant polymer on the mold cavity wall surface of a mold for molding a molded article having a complicated shape.

However, it has been found that there are various problems as described below in applying this method to a practical die.

(1) Depending on the mold shape, molding conditions, etc.,
Separation of the main mold and the heat insulating layer may occur. In particular, if the heat insulating layer is coated on a substantially right-angled acute angle portion of the mold wall, the heat-insulating layer applied to the acute angle portion is likely to be separated, and the shape of the molded product is reduced. Must be shaped so as to avoid right-angled portions.

(2) We studied the application of the heat-insulating layer-coated mold to blow molding. However, in blow molding, it is necessary to make the heat-insulating layer thicker. There is a problem that tends to occur.

(3) When a polymer is used as the heat insulating layer,
The thermal insulation layer is susceptible to damage during use and needs to be improved.

(4) In a mold covered with a heat insulating layer made of a polymer, if the synthetic resin to be molded has a polarity such as polyamide, it may be difficult to release the mold from the mold at the time of molding. Need improvement.

(5) By applying a metal layer to the surface of the heat insulating layer made of a polymer by metal plating or the like to prevent the heat insulating layer from being released or being damaged, it is necessary to heat the surface of the synthetic resin during molding. And cooling are repeated, and the metal layer on the surface is easily peeled off in this cooling / heating cycle, and it is necessary to prevent this.

[0013]

In order to solve these problems, the present inventors have studied a mold covered with a heat insulating layer, and have found that a heat insulating material covering the surface of the main mold and its coating state Investigating the combination of the main mold material and the thin metal layer covering the outermost surface of the heat insulating layer, the difference in the coefficient of thermal expansion between the heat insulating layer and the main mold, and between the heat insulating layer and the metal layer is small. It was discovered that it was extremely important and led to the present invention.

That is, according to the present invention , an aromatic ring is provided in the main chain on the mold wall surface forming the mold cavity of the metal main mold.
Heat resistance polymer that (excluding the thermosetting resin) A thermal barrier coating die and the heat insulating layer coating of the thermal expansion coefficient of the thermal expansion coefficient and the main mold of the heat insulating layer in contact with the main mold Is a molding method using a heat-insulating layer-coated mold having a difference of 2 × 10 ⁻⁵ / ° C. or less.

Further, the present invention relates to a heat-resistant polymer (excluding a thermosetting resin) having an aromatic ring in a main chain on a mold wall surface constituting a mold cavity of a metal main mold. And a third of the total heat insulation layer on the heat insulation layer surface.
A heat-insulating layer-coated mold coated with a metal layer having the following thickness, wherein a difference between a thermal expansion coefficient of the heat-insulating layer in contact with the coated metal layer and a thermal expansion coefficient of the metal layer is 2 × 10 ⁻⁵ / ° C. or less. This is a method for molding a synthetic resin molded article, characterized by molding using a heat-insulating layer-coated mold.

Further, the present invention provides the above-mentioned molding wherein both the difference in thermal expansion coefficient between the heat insulating layer and the main mold and the difference in thermal expansion coefficient between the heat insulating layer and the metal layer are 2 × 10 ⁻⁵ / ° C. or less. Is the law.

Hereinafter, the present invention will be described in detail.

The synthetic resin used in the present invention is a thermoplastic resin which can be used for general injection molding and blow molding, for example, polyolefin such as polyethylene and polypropylene, polystyrene, styrene-acrylonitrile copolymer, rubber-reinforced polystyrene, ABS Styrene resin such as resin, polyamide, polyester, polycarbonate,
Examples include methacrylic resin and vinyl chloride resin.

The synthetic resin preferably contains 1 to 60% of a resin reinforcement. Various types of rubber, glass fiber, carbon fiber and other fibers, talc,
Inorganic powders such as calcium carbonate and kaolin.

A synthetic resin that can be used particularly preferably is a rubber-reinforced synthetic resin. Among them, a rubber-reinforced styrene resin is more preferably used. The rubber-reinforced styrene-based synthetic resin described here refers to a rubber phase distributed in an island shape in a resin phase, for example, rubber-reinforced polystyrene, ABS resin, AA
Refers to S resin, MBS resin and the like.

In rubber-reinforced polystyrene, a rubber phase such as polybutadiene or SBR is dispersed in an island shape in a resin phase of a polymer mainly composed of styrene. In the ABS resin, a rubber phase such as polybutadiene and SBR is dispersed in an island shape in a resin phase of a copolymer mainly composed of styrene and acrylonitrile.
The AAS resin is a resin in which a rubber phase of an acrylic rubber is dispersed in an island shape in a resin phase of a copolymer mainly composed of styrene and acrylonitrile, and the MBS resin is a copolymer mainly composed of styrene and methyl methacrylate. It is a resin in which a rubber phase is dispersed in the form of islands in a resin phase composed of coalescing.

Further, blends and the like mainly composed of these resins can be used in the present invention. For example, a blend with a rubber-reinforced polystyrene resin containing polyphenylene ether can be used favorably. Injection molded products of these resins have an extremely good balance between performance and economy, and are suitable for housings of light electric appliances and the like.

Good molded articles molded by the molding method of the present invention are generally used synthetic resin injection molded articles such as housings for light electric appliances and electronic appliances, various automobile parts, various daily necessities, and various industrial parts. Particularly preferred is an injection-molded product having many weld lines and sharp corners, a housing of an electronic device or an electrical device having a multipoint gate and having a sharp angle of less than 1 mm in radius.

The main mold described in the present invention is generally a synthetic resin such as iron or a steel material containing iron as a main component, aluminum, an alloy containing aluminum as a main component, a zinc alloy such as ZAS, or a beryllium-copper alloy. Metal molds used for the molding of Particularly, a mold made of a steel material can be used favorably. It is preferable that the surface of the mold forming the mold cavity of the main mold made of these metals is plated with thin hard chrome, nickel, or the like. These platings are generally as thin as about 10 μm, and the coefficient of thermal expansion of the main mold depends on the metal constituting most of the main mold. The value of the coefficient of thermal expansion of the main mold is large. The value of the metal constituting the part is used.

The heat-resistant polymer used in the heat-insulating layer in the present invention is a polymer having a softening temperature higher than the molding temperature of the synthetic resin to be molded, and preferably has a glass transition temperature of 1
It is a heat-resistant polymer having a melting point of at least 40 ° C, preferably at least 160 ° C, and / or at least 200 ° C, more preferably at least 250 ° C. The thermal conductivity of a heat-resistant polymer is generally 0.0
001 to 0.002 cal / cm · sec · ° C.
Significantly smaller than metal. The breaking elongation of the heat-resistant polymer is preferably 5% or more, more preferably 10% or more.
% Is preferred. The elongation at break is measured according to ASTM D638, and the tensile speed at the time of measurement is 5 mm / min.

Polymers that can be used favorably as the heat insulating layer in the present invention are heat-resistant polymers having an aromatic ring in the main chain, and include various amorphous heat-resistant polymers, various polyimides, A thermosetting resin or the like can be used.

Examples of the non-crystalline heat-resistant polymer include polysulfone, polyethersulfone, and polyetherimide. These amorphous heat-resistant polymers can be used as a heat insulating layer of the present invention by lowering the coefficient of thermal expansion by blending carbon fibers or the like.

There are various types of polyimides, and linear high molecular weight polyimides, polyamideimides, and partially crosslinked polyimides can be used favorably. In general, straight-chain high molecular weight polyimides have large breaking elongation, are tough, have excellent durability, and can be used particularly favorably.

In the present invention, it is necessary that the thermal expansion coefficient of the heat-insulating layer made of a heat-resistant polymer in contact with the main mold and that of the main mold are close to each other. When covering the heat insulation layer with a metal layer,
It is necessary that the heat-insulating layer made of a heat-resistant polymer in contact with the coating metal layer and the metal layer have similar thermal expansion coefficients. That is,
In the present invention, the difference between the coefficient of thermal expansion of the heat insulating layer in contact with the main mold and the coefficient of thermal expansion of the main mold, or the difference between the coefficient of thermal expansion of the heat insulating layer in contact with the metal layer and the coefficient of thermal expansion of the metal layer, or both Is not more than 2 × 10 ⁻⁵ / ° C., preferably the difference is 1.
5 × 10 ⁻⁵ / ° C. or less, more preferably the difference is 1 × 10 ⁻⁵ / ° C.
It is below ° C. Generally, metals have a lower coefficient of thermal expansion than polymers, so it is necessary to select a heat-resistant polymer having a lower coefficient of thermal expansion.

The coefficient of thermal expansion of the present invention is a coefficient of linear expansion,
The coefficient of thermal expansion of the heat insulating layer is measured by the method shown in JIS K7197-1991, and is 50 ° C. when the average value between the temperature of 50 ° C. and 250 ° C. or the glass transition temperature of the heat insulating layer is 250 ° C. or less. The average value between the glass transition temperatures is shown. That is, a heat insulating layer is formed on a flat metal plate, and then the heat insulating layer is peeled off.
The average coefficient of thermal expansion between 50 ° C. or between 50 ° C. and the glass transition temperature is measured.

When the mold wall surface is covered with a heat insulating layer, the heat insulating layer is required to have various performances. In addition to adhesion to the main mold, which is the subject of the present invention, toughness, surface hardness, glossiness when the surface is polished, and the like are required. In addition to having a small coefficient of thermal expansion, it may be difficult to obtain a polymer satisfying all of these properties. From this viewpoint, it is preferable to use two or more heat insulating layers. That is, the object of the present invention is preferably achieved by using a polymer having a small coefficient of thermal expansion for the heat insulating layer on the side in contact with the main mold and using a polymer having excellent performance as a surface layer on the surface side. You. In this case, the two heat insulating layers need to have an adhesive property to each other, and it is preferable to select the same type of polymer as the heat insulating layer. In this case, the difference between the coefficient of thermal expansion of the heat insulating layer that is at least half of the total thickness of the heat insulating layer and the coefficient of thermal expansion of the main mold is 2 × 10 ^−5.
/ ° C or lower.

In the case where the heat-insulating layer in contact with the main mold is extremely thin among the multilayer heat-insulating layers, for example, the thickness of the heat-insulating layer in contact with the main mold is 1/5 or less of the total heat-insulating layer thickness, preferably 1 /.
In the case of 10 or less and about 10 μm or less,
The coefficient of thermal expansion of the heat insulating layer in contact with the main mold does not cause much problem, and the difference between the coefficient of thermal expansion of most heat insulating layers exceeding 4/5 of the entire heat insulating layer and the coefficient of thermal expansion of the main mold is 2. × 10
^-5 / ° C or less may be used. This is a case where a thin-walled primer is applied to the interface between the heat-insulating layer and the main mold in order to strengthen the adhesion between the heat-insulating layer and the main mold. The difference is 2 × 10 ^-5
Even if it exceeds / ° C, it is included in the present invention.

A metal for a main mold which can be favorably used in the present invention;
Table 1 shows the metal of the metal layer covering the outermost surface, the heat-resistant polymer of the heat-insulating layer, and the coefficient of thermal expansion of a general synthetic resin.

[0034]

[Table 1] * The thermal expansion coefficient of these resins can be reduced to around 4 × 10 ⁻⁵ / ° C. by blending carbon fibers.

When the thermal expansion coefficient of the main mold and the metal layer is increased, a heat insulating layer having a relatively large thermal expansion coefficient can be used. Steel is most often used as a mold material, but recently aluminum alloys and zinc alloys such as ZAS have been used. Aluminum alloys and zinc alloys have a higher coefficient of thermal expansion than steel. Therefore, general polyimides can be used in the present invention if they are combined with aluminum alloys or zinc alloys. However, the closer the coefficient of thermal expansion is, the more preferable. When steel is used for the main mold, low thermal expansion type polyimide or the like having an extremely small coefficient of thermal expansion can be used favorably. Table 2 shows the thermal expansion coefficients of various low thermal expansion polyimides.

[0036]

[Table 2]

In the table, Bixix and Free are imidized by allowing the film to be freely shrunk (Free) when immobilizing the polyimide precursor to form a polyimide film, or by fixing the film to a square frame. It has the meaning of whether or not the polymer chains are orientated in-plane by the stress while suppressing the shrinkage that sometimes occurs (Bixix). After applying the polyimide precursor solution to the main mold, the polyimide formed by heating has a coefficient of thermal expansion close to Bifix. The low thermal expansion type polyimide is a polymer having a polymer chain structure in which a polymer chain is rigid and extends straight. For example, in the polyimide shown in FIG. 15, the polymer chain is bent, whereas in the polyimide shown in FIG. 16, the polymer chain extends straight and is a low thermal expansion type polyimide.

Table 3 shows the structure and glass transition temperature (Tg) of the heat-resistant polymer which can be favorably used in the present invention.

[0039]

[Table 3]

Injection molding has economic value in that a molded article having a complicated shape can be obtained by one molding. In order to coat the complex mold surface with the heat-resistant polymer and to firmly adhere thereto, a heat-resistant polymer solution and / or a heat-resistant polymer precursor solution is applied, and then heated to heat-resistant polymer. Most preferably, a heat insulating layer is formed. Therefore, it is preferable that the heat-resistant polymer or the precursor of the heat-resistant polymer can be dissolved in a solvent. A method in which a solution of a polyamic acid, which is a precursor of polyimide, is applied to a mold wall surface and then cured by heating to form polyimide on the mold wall surface can be used favorably. Formula 1 shows a formula for forming a polyimide from a polyamic acid.

[0041]

Embedded image

When a polyamic acid solution of a polyimide precursor is applied to the mold wall surface and then cured by heating to form a polyimide, the glass transition temperature and the coefficient of thermal expansion of the polyimide differ depending on the heating cure temperature and / or the heating cure atmosphere. . Generally, the higher the heating cure temperature, the higher the glass transition temperature tends to be. Polyamic acid is generally 250 ° C
By doing so, the imidization proceeds almost 100% to form a polyimide, but it is considered that the movement of the molecules after the polyimide affects the glass transition temperature and the thermal expansion coefficient.

It is preferable to add an imidization accelerator to the polyimide precursor solution and imidize at as low a temperature as possible. An imidization accelerator is a substance capable of accelerating imidization of a precursor by mixing the imidization accelerator with a linear high-molecular-weight polyimide precursor solution and promoting imidization at a low temperature. is there. Examples of the imidization accelerator include various organic acids and bases.
Pyridine / acetic anhydride mixture, m-hydroxybenzoic acid, p-hydroxybenzoic acid, 2,4
-Dihydroxybenzoic acid, p-hydroxyphenylacetic acid, 3- (p-hydroxyphenyl) propionic acid, p-phenolsulfonic acid, p-aminophenol, m-aminobenzoic acid, p-aminobenzoic acid, 2 -(4-hydroxyphenyl) isovaleric acid, 2- (4-hydroxyphenyl) -2- (4
-Aminophenyl) propane, p-hydroxybenzaldehyde and the like can be used favorably.

The thermal expansion coefficient of iron most frequently used as the main mold is smaller than that of general polyimide. When a polyimide precursor solution having a large coefficient of thermal expansion is applied to the surface of a metal mold having a small coefficient of thermal expansion and imidized at a high temperature close to 300 ° C., the polyimide and the mold adhere to each other at a high temperature at which imidization is performed. Upon cooling to room temperature, residual stress proportional to the difference in the coefficient of thermal expansion remains in the polyimide layer. This residual stress causes peeling of the polyimide layer in tens of thousands of thermal cycles during molding of the synthetic resin.

As a result of measuring the strain remaining in the polyimide of the mold coated with the polyimide, the following was found. That is, when the polyimide precursor is heated and imidized, there is generally a large volume shrinkage of more than 10%. However, the amount of the large volume shrinkage during imidization that remains as residual strain is relatively small. It was discovered that the temperature difference between cooling from high temperature to room temperature and the difference in thermal expansion coefficient between polyimide and the mold caused large distortion. Although the absolute value of the amount of shrinkage caused by the difference between the temperature difference and the coefficient of thermal expansion is not so large, it has been found that the influence on the residual strain is large. By imidizing the polyimide precursor at a low temperature of room temperature to 200 ° C., the residual stress of the polyimide layer of the heat insulating layer can be further reduced, and the occurrence of peeling can be reduced.

Further, in the present invention, a thermosetting resin having a small coefficient of thermal expansion can be used. Epoxy resins, particularly epoxy resins having a low coefficient of thermal expansion obtained by mixing various fillers in appropriate amounts, can be used. Epoxy resins generally have a large coefficient of thermal expansion, and the difference in coefficient of thermal expansion from a metal mold is large. A suitable amount of powder or particles such as glass, silica, talc, clay, zirconium silicate, calcium silicate, lithium silicate, calcium carbonate, alumina, mica, etc. having a small coefficient of thermal expansion, glass fiber, whisker, carbon fiber, etc. is mixed with epoxy resin. ,
A filler-containing epoxy resin having a difference in thermal expansion coefficient from the main mold of less than 2 × 10 ⁻⁵ / ° C. can be used as the heat insulating layer of the present invention.

The epoxy resin is further blended with a tough polymer such as nylon, polyethersulfone or polyetherimide to provide toughness, and a filler having a small thermal expansion coefficient is blended to lower the thermal expansion coefficient. Epoxy resin formulations with toughness can be used particularly well. The compounding amount of the filler-containing epoxy resin is appropriately selected in the range of 15 to 75% by weight, and preferably 20 to 70% by weight. The relationship between the blending amount of the filler and the coefficient of thermal expansion varies depending on the type of the filler, the type of the epoxy resin, and the like. For example, silica and lithium silicate generally have values shown in Table 4.

[0048]

[Table 4]

The adhesion between the heat insulating layer of the present invention and the main mold must be large, and is preferably 0.5 kg / 10 mm or more at room temperature, more preferably 0.8 kg / mm.
The width is 10 mm or more, more preferably 1 kg / 10 mm or more. This cuts the adhered heat insulation layer to a width of 10 mm,
This is the peeling force when the cutting width is pulled at a speed of 20 mm / min in a direction perpendicular to the adhesive surface. Although this peeling force varies considerably depending on the measurement location and the number of measurements, it is important that the minimum value is large, and it is preferable that the peeling force be stably large. The adhesion described in the present invention is the minimum value of the adhesion of the main part of the mold. In order to improve the adhesion, it is possible to appropriately form the surface of the main mold into fine irregularities, perform various plating, or perform a primer treatment.

Further, when a metal layer is provided on the surface of the heat insulating layer, it is necessary that the adhesion between the heat insulating layer and the outermost metal layer be similarly large. Approximately the same level of adhesion is required.

The greatest advantage of injection molding is that a mold having a complicated shape can be formed by one molding, and therefore, the mold cavity generally has a complicated shape. However, it is extremely difficult to apply a coating material to the surface of the mold cavity having a complicated shape in a mirror-like manner. Therefore, the best method is to polish the applied coating layer later to finish the mirror-like shape. It is.

The total thickness of the heat insulating layer is appropriately selected in the range of 0.05 mm to 1 mm. Particularly preferably, it is 0.05 mm to 0.2 mm in injection molding and 0.2 mm to 0.5 mm in blow molding. 0.05mm
When the heat insulating layer is thinner than the above, the effect of improving the appearance of the molded article is small. If the thickness of the heat insulating layer exceeds 1 mm, the cooling time in the mold becomes long, which is not preferable from an economic viewpoint.

The surface of the main mold is covered with a heat-insulating layer made of a heat-resistant resin. When the injected heated resin comes into contact with the surface of the heat-insulating layer, the surface of the mold is heated by the heat of the resin. The lower the thermal conductivity of the heat insulating layer and the thicker the heat insulating layer, the higher the mold surface temperature. In the present invention, in the injection molding using the heat-insulating layer-coated mold whose outermost surface is formed of a heat-insulating layer, after the injected synthetic resin comes into contact with the cooled heat-insulating layer surface, the heat insulating is performed for at least 0.1 second. The layer surface temperature (the interface temperature between the heat insulating layer and the synthetic resin) is preferably at or above the softening temperature of the resin to be molded, more preferably at least 0.2 seconds. When there is no heat insulating layer on the mold surface of the main mold made of a general metal, the mold surface temperature becomes almost the same as the main mold temperature after 0.01 second, but the mold surface is kept at 0.
By covering with a heat-insulating layer having a thickness of 05 mm to 1 mm, the thickness of the heat-insulating layer is reduced to 0.1 mm.
The mold surface can be kept at the softening temperature or higher for 1 second or longer.

The change in the mold surface temperature during injection molding can be calculated from the temperature, specific heat, thermal conductivity, density, latent heat of crystallization, etc. of the synthetic resin, main mold, and heat insulating layer. For example, ADINA and A
Using DINAT (software developed at the Massachusetts Institute of Technology) or the like, it can be calculated by an unsteady heat conduction analysis by a nonlinear finite element method.

The softening temperature of the resin described herein is a temperature at which the synthetic resin can be easily deformed. Vicat softening temperature (ASTM D1525) for an amorphous resin, and heat deformation temperature (ASTM D648 load 18) for a hard crystalline resin. .6
kg / cm2), and the heat distortion temperature (AS
TM D648 under a load of 4.6 kg / cm 2). The hard crystalline resin is, for example, polyoxymethylene, nylon 6, nylon 66, and the like, and the soft crystalline resin is, for example, various polyethylenes, polypropylenes, and the like.

In the present invention, in order to further improve the smoothness and the like of the surface of the thin layer of the heat insulating material, to further improve the abrasion resistance of the surface, and to improve the releasability, a half of the thickness of the heat insulating layer is used. Another material having the following thickness can be coated on the surface of the heat insulating layer. For example, on the surface of a synthetic resin or mold,
A coating generally used as a hard coat, which is used for improving scratch resistance, can be applied. However, in the present invention, as described above, the above object can be achieved favorably by covering the surface of the heat insulating layer with a thin metal layer.

The metal used for the metal layer coated on the outermost surface of the heat insulating layer of the mold used in the present invention is a metal formed by plating, thermal spraying or the like.
Zinc, iron, aluminum, titanium, tin-cobalt alloy,
One or more of iron-nickel alloys and the like.

The thickness of the metal layer is 1/3 of the thickness of the entire heat insulating layer.
It is as follows. Preferably, the thickness is 1/4 or less, and 0.00
1 to 0.2 mm, more preferably 0.003 to 0.05
mm. When the surface of the metal layer is uneven, such as a grain shape or a mat shape, the average thickness indicates the metal layer thickness. If the metal layer on the surface of the heat insulating layer is too thick, the effect of covering the heat insulating layer is lost, and if it is too thin, the effect of coating the metal layer is lost. Since the metal has higher thermal conductivity and heat capacity than a heat insulating layer such as polyimide, when the heated thermoplastic resin to be molded comes into contact with the cooled metal layer, the metal is temporarily attached to the interface between the thermoplastic resin and the metal layer. Cooling occurs. If the metal layer is thin, the interface immediately rises in temperature and becomes higher than the softening temperature of the thermoplastic resin, and the mold surface reproducibility is improved. The thicker the metal layer, the longer it takes to raise the temperature, the lower the temperature rises, the less the effect of coating the heat insulating layer, and the worse the mold surface reproducibility.

The metal layer can be coated on the surface of the heat insulating layer by various methods, but can preferably be coated by plating or the like. The plating described herein is to adhere a thin layer of a hard metal to the surface of the heat insulating layer. Particularly, in the present invention, plating in which chromium and nickel, which have high hardness and are not easily scratched, are present on the outermost surface is preferable. The plating method may be any of chemical plating and electroplating. For example, first, the surface of the heat insulating layer is made a moderately rough surface, a conductor such as copper is deposited on the surface to impart conductivity, and then nickel, chromium and other metals are electroplated, and nickel is coated by chemical plating. Can be used. Generally, plating is performed through some of the following steps.

Chemical corrosion (chemical etching with acid or alkali, etc .: making the surface moderately uneven) → Neutralization → Sensitivity treatment (adhesion of a metal salt having a reducing power to the surface of the synthetic resin to effectively activate it) Activate) (Activate precious metal with a catalytic action on the resin surface) → Chemical nickel plating (chemical plating of nickel) → Copper electroplating (electroplating of copper) → Electric nickel plating (electroplating of nickel) →
Electrochrome plating (chrome electroplating) (for details, see "Plastic plating" by Shigeru Romo, published in 1974, published by Nikkan Kogyo Shimbun, etc.).

In order to make the surface of the heat-insulating layer moderately uneven by chemical corrosion, a heat-insulating layer containing a fine powder of calcium carbonate, silicon oxide or the like is preferably present on the surface layer of the heat-insulating layer. . In other words, when calcium carbonate or silicon oxide is blended in the heat insulating layer of polyimide or the like, calcium carbonate or silicon oxide on the surface is eluted by acid treatment or alkali treatment, and the unevenness of the traces increases the force of adhering the plating layer to the surface. Let it.

In injection molding, blow molding and the like, the mold surface in contact with the resin to be molded is subjected to a severe cooling / heating cycle for each molding. In the prior art, the metal layer formed on the surface of the heat insulating layer by plating or the like generally has a smaller coefficient of thermal expansion than the heat insulating layer made of a polymer, and the coefficient of thermal expansion between the heat insulating layer and the metal layer is greatly different. The stress is repeatedly generated, and if the molding is performed 10,000 times, the stress is repeatedly generated 10,000 times, and finally, the separation occurs at the interface. The temperature of the interface between the thin metal layer and the heat insulating layer on the surface of the heat insulating layer greatly fluctuates during molding, and the temperature fluctuation at the interface between the thin metal layer and the heat insulating layer depends on the temperature of the interface between the heat insulating layer and the main mold. It is much larger than the width of the vertical movement, and the force that causes peeling is greater. In the present invention, a material having an extremely close coefficient of thermal expansion of 2 × 10 ⁻⁵ / ° C. or less, which is a difference between the coefficient of thermal expansion of the heat insulating layer in contact with the metal layer and the coefficient of thermal expansion of the metal layer, is selected to reduce the stress causing peeling. Things.

In general, when metal plating is performed on the surface of a synthetic resin, copper, which is one of the most flexible metals, is first coated thickly on the resin layer, and nickel and / or chromium having high hardness are coated thereon. By performing multi-layer plating such as coating, problems such as peeling caused by a difference in thermal expansion coefficient have been avoided. For example, plating has been performed in the order of copper, nickel, and chromium to make copper equal to or more than ／ of the total plating thickness, but the problem of peeling has not been sufficiently solved. The difference in the coefficient of thermal expansion described in the present invention is 2 × 10 ^−5.
By using a material whose coefficient of thermal expansion is very close to / ° C or less, there is no need to make the plating layer thicker than necessary.
A good mold that can withstand long-term molding can be obtained.

The cause of the separation between the heat insulating layer and the main mold is not only the difference in thermal expansion coefficient, but the difference in thermal expansion coefficient is an extremely large factor. In the case of a so-called rubber-like heat-insulating layer having a large adhesive force between the heat-insulating layer and the main mold, a small tensile elastic modulus of the heat-insulating layer, and a large elongation at break, the difference in thermal expansion coefficient is slightly large. No peeling occurs. However, a material suitable for the heat insulating layer, that is, a heat insulating material that has a high heat resistance, a large hardness, and a material that easily becomes a mirror surface by polishing,
Generally, it is a heat-resistant hard synthetic resin having an aromatic ring in the main chain having a large elastic modulus, and in order to keep this heat-resistant synthetic resin layer in close contact with the main mold and not to cause peeling, the difference in thermal expansion coefficient is required. Very small is very preferred.

As described above, the present invention has been mainly described with respect to injection molding and blow molding, but other molding methods using a mold can also be used.
For example, compression molding, sheet vacuum forming or pressure forming,
A method in which a corrugated pipe is formed using a corrugated mold for the extruded tube can also be used.

Hereinafter, the present invention will be described with reference to the drawings.

FIGS. 1 to 3 show a steel main mold temperature of 50.
The change (calculated value) of the temperature distribution in the vicinity of the mold wall surface when the temperature of the rubber-reinforced polystyrene is 240 ° C. and the temperature is 240 ° C.

FIGS. 4 to 9 show a main mold made of steel using a mold having a surface coated with a polyimide layer and a nickel layer on the surface thereof, and a mold having a surface coated with a nickel layer alone. Is set to 50 ° C., and when the temperature of the rubber-reinforced polystyrene resin is injection-molded in the mold at 240 ° C., the temperature of the resin surface after the injected resin comes into contact with the outermost surface of the mold ( This indicates a temporal change (calculated value) of the temperature at the interface between the resin surface and the nickel surface or the temperature between the resin surface and the polyimide surface.

FIGS. 10 to 11 illustrate a case where a synthetic resin is blow-molded by the molding method of the present invention.

FIG. 12 shows that the steel main mold temperature is 70 ° C.
The temperature change (calculated value) of the mold surface (polyimide surface) when the temperature of the ABS resin is blow molded at 220 ° C. is shown.

FIG. 13 shows the peeling of the heat insulating layer which occurs when a heat insulating material is applied to the wall surface of the mold cavity at a right angle.

FIG. 14 shows an example of a method of coating a heat insulating layer on the surface of the main mold.

In FIG. 1, FIG. 2 and FIG. 3, changes in the temperature distribution near the mold wall surface when the temperature of the main mold made of steel is 50 ° C. and the temperature of the rubber reinforced polystyrene is 240 ° C. (Calculated value). The numerical value of each curve in the figure indicates the time (second) from when the heated synthetic resin comes into contact with the cooled mold wall. In the case where the heat insulating layer does not exist in the main mold (FIG. 1), the heated synthetic resin comes into contact with the mold wall surface and is rapidly cooled. When the heat insulating layer is present in the main mold (FIGS. 2 and 3), the mold surface is heated by receiving heat from the heated synthetic resin. As shown in the figure, when the mold surface is covered with a heat insulating layer (polyimide) of 0.1 mm and 0.5 mm (FIGS. 2 and 3), the temperature rise on the surface of the heat insulating layer in contact with the synthetic resin increases, The rate of decrease also decreases.

In the heat-insulating layer-coated mold, the shorter the time from the contact of the synthetic resin with the mold wall, the higher the mold surface temperature (the temperature at the interface between the synthetic resin and the heat-insulating layer). The same effect as when the temperature is greatly increased is obtained, and the increase in the molding cycle time is small. From this figure, the mold surface temperature after a short time from when the synthetic resin comes into contact with the mold surface and the injection pressure is applied to the resin to press the mold surface can be read from this curve.

4, 5, 6, 7, 8, and 9, a mold in which a polyimide layer is coated on the surface of a main mold made of steel, and a nickel layer is further coated on the surface, As a comparison, a mold coated with only the polyimide layer was used, the temperature of the main mold was set to 50 ° C., and when the temperature of the rubber-reinforced polystyrene resin was injection-molded with the mold at 240 ° C., the resin was The graph shows the change with time of the temperature of the resin surface after contact with the outermost surface of the mold (this is the temperature of the interface between the resin surface and the nickel surface or the temperature of the interface between the resin surface and the polyimide surface).

FIG. 4 shows the aging of the resin surface temperature when the thickness of the polyimide (hereinafter, indicated by PI) is 0.30 mm and the thickness of the nickel (hereinafter, indicated by Ni) is 0.02 mm. Indicates a change. In the figure, the solid line is the case where the polyimide layer and the nickel layer are covered, and the broken line is the case where only the polyimide layer is covered. When coated only with polyimide, the resin surface temperature decreases with the passage of time, whereas when coated with a polyimide layer and a nickel layer, the temperature once drops significantly and then gradually rises and then gradually drops . This is because the heat of the resin is absorbed by the nickel layer and decreases because the heat capacity of nickel in the surface layer is large. Therefore, as the thickness of the nickel layer increases,
The temperature range that once decreases increases.

FIG. 5 shows the case where the thickness of the nickel layer is increased to 0.1 mm. When the thickness of the nickel layer is increased, the temperature range in which the temperature once decreases is large, and the temperature in which the temperature rises again decreases.

FIGS. 6 and 7 show a case where the thickness of the polyimide layer is 0.15 mm in the same layer structure as in FIGS. 4 and 5. FIG. Even when the thickness of the polyimide layer is 0.15 mm, the same tendency as in FIGS. 4 and 5 is observed.

FIG. 8 and FIG. 9 collectively show the results of FIG. 4 to FIG. 8 and 9, in the case of this mold coated with a nickel layer, when the thickness of the nickel layer is 0.1 mm, the temperature of the resin surface is lowered, and the mold surface reproducibility during injection molding is poor. It can be estimated that When the thickness of the nickel layer is 0.02 mm, the resin surface temperature recovers rapidly even if it once drops, so that the mold surface reproducibility during injection molding is good. From these facts, there is a limit to the thickness of the metal layer covering the heat insulating layer surface. Therefore, the thickness of the metal layer is generally preferably from 0.001 to 0.2 mm, more preferably from 0.003 to 0.05 mm. Selected.

In FIG. 10 and FIG. 11, a heat insulating layer 2 is formed on the wall surface of the mold forming the mold cavity 3 of the main mold 1 made of metal.
And, if necessary, a thin metal layer 5 on the surface.
Is coated.

When the parison 4 of the synthetic resin extruded by heating and plasticizing is clamped by a mold, the portions A and B of the parison 4 come into contact with the mold wall surface. Next, a pressurized gas body is blown into the parison and blow-molded to obtain a blow-molded product 6 shown in FIG. The portions A 'and B' of the blow-molded product 6 have a long time from contact with the mold wall surface, and if the thickness of the heat insulating layer is not sufficient, the reproducibility of the mold surface deteriorates.

FIG. 12 shows the temperature change on the mold surface (polyimide surface) when the main steel mold is coated with polyimide. As described in the previous figure, when the time after the extruded heated parison comes into contact with the mold wall surface becomes longer, the mold surface temperature rapidly decreases. In order to improve the mold surface reproducibility during molding, the mold surface temperature when a blow pressure is applied must be equal to or higher than the softening temperature of the synthetic resin. As shown in FIG. There is a need to. Generally, the time from contact to the application of blow gas pressure is 3 to
5 seconds, so the thickness of the thermal insulation layer is generally 0.3 mm
The above is required.

When the thickness of the heat insulating layer is increased, a stress is generated between the layers at the time of coating and / or molding the heat insulating layer due to the difference between the thermal expansion coefficient of the heat insulating layer and the thermal expansion coefficient of the main mold and the metal layer. Peeling is likely to occur at the interface. In the present invention, to reduce the stress generated by reducing the difference between the coefficient of thermal expansion of the heat insulating layer and the coefficient of thermal expansion of the main mold, to obtain a practical mold that does not peel even when the heat insulating layer is thick. Can be. As described in the description of peeling at the interface between the main mold and the heat insulating layer, the stress generated at the interface between the heat insulating layer and the metal layer when the surface of the heat insulating layer is covered with the metal layer also becomes smaller as the coefficient of thermal expansion of the both becomes closer. And peeling is less likely to occur.

FIG. 13 is a view for explaining a case in which a heat insulating layer is applied to a mold wall surface of an injection molding die having a corner portion close to a right angle. Have a department. When a precursor solution of a heat insulating material or a solution 8 of a heat insulating material is applied to the main mold 7 (a), and then the applied main mold is heated to a high temperature in a heating oven to form a heat insulating layer 9, The heat insulating layer 9 generally has a larger coefficient of thermal expansion than the metal main mold, so that it is pulled when cooled to room temperature, and peels off at the acute angle portion 10 (b). Separation is likely to occur when the radius of the corner is 1 mm or less, particularly 0.5 mm or less, which is an acute angle close to a right angle.

In order to prevent the occurrence of peeling of the corners 10, in the present invention, a material whose thermal expansion coefficient of the heat insulating layer is close to that of the main mold is selected. By selecting a combination with a thermal expansion coefficient close to that of the heat insulating layer and the main mold, it is heated and cured at high temperature,
Even when cooled to room temperature, the generated stress is minutely suppressed.
Further, even when being molded by the heat-insulating-layer-coated mold, the generated stress is minutely suppressed, and peeling does not occur.

Various methods are conceivable for coating the heat insulating layer on the main metal mold. As described above, a method in which a heat insulating material solution or a precursor solution of a heat insulating material is applied to a main mold, and then cured by heating to form a heat insulating layer can be favorably used. However, methods other than the solution coating method can be used. FIG. 8 shows another method of coating the heat insulating layer with a blow mold.

In FIG. 14, the main mold 11 made of metal is used.
The mold wall surface is provided with pores 12 for suctioning into a vacuum. The pore 12 is connected to a suction port 14 via a conduit 13 (a). A sheet 15 of a heat-resistant polymer having an adhesive layer on the side of the main mold 11 is placed on the mold cavity surface (b). The main mold 11 and the heat-resistant polymer sheet 15 are placed in a heating oven, heated to a temperature equal to or higher than the softening temperature of the heat-resistant polymer sheet, and vacuumed from the suction port 14 in a heated state.
The heat-resistant polymer sheet is formed into a mold wall shape, and the mold wall surface is covered with the heat-resistant polymer (c). The whole is cooled to room temperature while continuing to apply a vacuum, and then the heat-insulating layer other than the mold cavity surface is removed. Further, if necessary, a thin metal layer 17 is applied to the surface of the heat insulating layer by plating, and finally, a pore 16 for degassing is opened to obtain a heat insulating layer coating mold of the present invention for blow molding (d). ).

When a heat-insulating-layer-coated mold is made by the method shown in FIG. 14, if the thermal expansion coefficients of the main mold and the metal layer are close to those of the heat-resistant polymer, the generated stress is extremely small. The mold is obtained. This heat insulating layer coating method is 0.3
The heat-insulating layer having a thickness of not less than mm is required, and can be favorably used for a mold for coating a heat-insulating layer for blow molding having a relatively gentle curved cavity shape.

[0089]

EXAMPLES The following main molds and heat insulating layers are used.

Main die 1: 300 × 95 × 20 mm (made of steel (S55C), parison extrusion direction: 30
0 mm) having a rectangular parallelepiped mold cavity. The surface of the mold is hard chrome plated with a thickness of about 5 μm. The thermal expansion coefficient of the main mold is 1.1 × 10 ⁻⁵ / ° C.

Main mold 2: A mold made of a zinc alloy (ZAS) and having a rectangular cavity having the same shape as the main mold 1. The surface of the mold is hard chrome plated with a thickness of about 5 μm. The thermal expansion coefficient of the main mold is 2.8 × 10 ^-5 / ° C.

Main mold 3: A front panel mold of a portable radio cassette player (radio, cassette tape recorder) made of zinc alloy (ZAS). The mold has a five-point gate, and has a nearly right-angled sharp corner on the mold cavity wall. The surface of the mold is hard chrome plated with a thickness of about 5 μm. The thermal expansion coefficient of the main mold is 2.8 × 10 ^-5 / ° C.

Insulation layer 1: Treenice 3000 (trade name,
Toray Co., Ltd.) is applied and heated at 160 ° C., and then this application and heating are repeated to obtain a predetermined thickness.
The polyimide layer is formed by heating to 0 ° C. and then polished to a mirror surface. The thermal expansion coefficient of the cured polyimide is 3.3 × 10 ⁻⁵ / ° C.

Insulation layer 2: Sheet in which carbon fibers are mixed with polyetherimide. The thermal expansion coefficient of this carbon fiber-containing polyetherimide is 4.6 × 10 ^-5 / ° C.

Primer layer: Lark TPI (trade name, manufactured by Mitsui Toatsu Chemicals, Inc.) is applied and heated at 170 ° C. to form a primer layer, on which a heat insulating layer is coated. The thermal expansion coefficient of the primer layer after heat curing is 4 × 10 ⁻⁵ /
° C.

Metal layer: Chemical nickel plating. The thermal expansion coefficient of the nickel is 1.3 × 10 ⁻⁵ / ° C.

Example 1 and Comparative Example 1 The main mold 1 and the main mold 2 are each coated with a heat insulating layer 2 to a thickness of 0.35 mm. The ABS resin is extrusion-blow-molded using the heat-insulating layer-coated mold. Table 5 shows the results.

[0098]

[Table 5]

In Example 1 in which the difference between the coefficient of thermal expansion of the heat insulating layer and the coefficient of thermal expansion of the main mold is 0.5 × 10 ⁻⁵ / ° C., the heat insulating layer is obtained immediately after coating the heat insulating layer and further after blow molding. Does not occur. In the comparative example in which the difference is 2.2 × 10 ⁻⁵ / ° C., peeling occurs in a part of the heat insulating layer immediately after coating the heat insulating layer.

Example 2 Approximately 2 μm on the mold wall surface of the main mold 3
Is formed, and then the heat insulating layer 1 is set to a thickness of 0.1 mm.
Coat to a thickness of 15 mm. A rubber-reinforced polystyrene resin is injection-molded using the heat-insulating layer-coated mold.

The difference between the coefficient of thermal expansion of the heat insulating layer and the coefficient of thermal expansion of the main mold is 0.5 × 10 ⁻⁵ / ° C., even after coating the heat insulating layer and further after injection molding. Peeling of the heat insulating layer at the sharp corner does not occur. Using this mold, a rubber-reinforced polystyrene resin is injection-molded to obtain a good injection-molded product with less noticeable weld lines. By this molding method, post-processing such as painting of the molded article can be omitted.

[Example 3] At the time of forming the heat insulating layer 1 of Example 2, a heat insulating material containing calcium carbonate fine powder was coated on the outermost surface to a thickness of 0.01 mm and then heated to 290 ° C to form a heat insulating layer. The surface of the heat insulating layer is etched with oxygen to make the surface of the heat insulating layer fine and rough, and then a nickel layer having a thickness of 0.005 mm is plated as a metal layer on the surface. The difference in the coefficient of thermal expansion between the metal layer and the heat insulating layer is 2.0 × 10 ⁻⁵ / ° C. An ABS resin having a high acrylonitrile content is injection-molded using the mold. There is no peeling of the metal layer due to the molding, the releasability at the time of molding is good, and a good molded product with less noticeable weld lines can be obtained. In contrast, when injection molding is performed using the mold of Example 2 having no nickel layer, the releasability during molding is poor.

[Embodiment 4] Approximately 2 μm
Is formed, and the surface thereof is coated with a heat insulating layer 1 having a thickness of 0.35 mm in the same manner as in Example 1. This heat-insulating layer adheres sufficiently to the main mold, and the heat-insulating layer does not peel off immediately after the heat-insulating layer coating or after the molding.

[Embodiment 5] The heat insulating layer 2 is provided on the main mold 2 as shown in FIG.
Coating is performed by the method described above. The mold wall of the main mold is coated in advance with a rubber-based adhesive and adhered by vacuum molding. The mold is cooled to room temperature while being sucked in vacuum to obtain a mold covered with the heat insulating layer 2. Using this mold, an ABS resin is blow-molded to obtain a blow-molded article having a good appearance.

[0105]

According to the present invention, injection molding or blow molding of a synthetic resin using a specific mold coated with a heat insulating layer eliminates the occurrence of peeling of the heat insulating layer and provides a molded article having a good appearance. In particular, conventionally many weld lines occurred,
Injection molded products, such as housings of light electrical appliances, which require post-processing such as painting, can be made unpainted by the method of the present invention.

[Brief description of the drawings]

FIG. 1 shows a change (calculated value) of a temperature distribution near a mold wall surface when a heated synthetic resin comes into contact with a steel main mold.

FIG. 2 shows a change (calculated value) of a temperature distribution near a mold wall surface when a heated synthetic resin is brought into contact with a mold in which 0.1 mm polyimide is coated on a mold surface of a steel main mold. Show.

FIG. 3 shows a change (calculated value) of a temperature distribution near a mold wall surface when a heated synthetic resin is brought into contact with a mold in which 0.5 mm of polyimide is coated on a mold surface of a steel main mold. Show.

FIG. 4 is a diagram illustrating a synthesis when a heated synthetic resin is brought into contact with a mold in which 0.3 mm of polyimide is coated on the surface of a steel main die and 0.02 mm of nickel is further coated on the surface of the main die. The temperature change (calculated value) of the resin surface (the interface between the resin surface and the mold surface) is shown.

FIG. 5 is a diagram illustrating a synthesis when a heated synthetic resin is brought into contact with a mold in which 0.3 mm of polyimide is coated on the surface of a steel main die and 0.1 mm of nickel is further coated on the surface of the main die. The temperature change (calculated value) of the resin surface (the interface between the resin surface and the mold surface) is shown.

FIG. 6 is a diagram showing a synthesis when a heated synthetic resin is brought into contact with a mold in which a mold surface of a steel main mold is coated with a polyimide of 0.15 mm and the surface thereof is further coated with nickel of 0.02 mm. The temperature change (calculated value) of the resin surface (the interface between the resin surface and the mold surface) is shown.

FIG. 7 shows the synthesis when a heated synthetic resin comes into contact with a mold in which a mold surface of a steel main mold is coated with 0.15 mm of polyimide and the surface thereof is further coated with nickel of 0.1 mm. The temperature change (calculated value) of the resin surface (the interface between the resin surface and the mold surface) is shown.

FIG. 8: A mold surface of a steel main mold is coated with 0.3 mm of polyimide, and the surface is further covered with 0.0005 mm, 0,
The temperature change (calculated value) of the synthetic resin surface (the interface between the resin surface and the mold surface) when the heated synthetic resin is brought into contact with the mold coated with nickel of each thickness of 02 mm and 0.1 mm is shown.

FIG. 9: A mold surface of a steel main mold is coated with 0.15 mm of polyimide, and the surface is further coated with 0.0005 mm of polyimide.
The temperature change (calculated value) of the synthetic resin surface (interface between the resin surface and the mold surface) when the heated synthetic resin comes into contact with the mold coated with nickel of each thickness of 0.02 mm and 0.1 mm. Show.

FIG. 10 is an explanatory view of blow molding a synthetic resin with the mold of the present invention.

FIG. 11 is an explanatory view of blow molding a synthetic resin with the mold of the present invention.

FIG. 12 shows a temperature change (calculated value) of a mold surface (polyimide surface) when blow molding at a steel main mold temperature of 70 ° C. and an ABS resin temperature of 220 ° C.

FIG. 13 shows peeling of a heat insulating layer at a right angle portion of a mold, which occurs when a heat insulating material is applied to a wall surface of a right angle mold cavity.

FIG. 14 shows an example of a method of coating a heat insulating layer on a main mold surface.

FIG. 15 is a view showing a bent polyimide.

FIG. 16 is a view showing a low thermal expansion type polyimide.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 main mold 2 heat insulating layer 3 mold cavity 4 parison 5 metal layer 6 blow molded product 7 main mold 8 heat insulating material solution 9 heat insulating layer 10 acute angle section 11 main mold 12 pore 13 conduit 14 suction port 15 heat resistant heavy Coalescing sheet 16 Gas release pores 17 Metal layer

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Claims (7)

(57) [Claims] 1. A heat-resistant polymer having an aromatic ring in a main chain on a mold wall surface constituting a mold cavity of a metal main mold.
A heat-insulating layer-coated mold coated with a heat-insulating layer made of (excluding a thermosetting resin) , wherein the difference between the coefficient of thermal expansion of the heat-insulating layer in contact with the main mold and the coefficient of thermal expansion of the main mold is 2 ×. A molding method of a synthetic resin molded article, characterized in that the molding is performed using a heat-insulating layer-coated mold having a temperature of 10 ^-5 / ° C or less. 2. The method according to claim 1, wherein the heat-resistant polymer is dissolved in an organic solvent.
A non-crystalline heat-resistant polymer or polyimide
1. A method for molding a synthetic resin molded article according to 1. 3. The method according to claim 1, wherein the heat-resistant polymer is a linear high molecular weight polymer.
The method for molding a synthetic resin molded article according to claim 1, which is a polyimide. 4. A heat-resistant polymer having an aromatic ring in a main chain on a mold wall surface of a mold cavity of a main mold made of metal.
A heat-insulating layer coating mold in which a heat-insulating layer made of (excluding a thermosetting resin) is coated, and the surface of the heat-insulating layer is further coated with a metal layer having a thickness of 1/3 or less of the entire heat insulating layer. A synthetic resin molded article formed by using a heat-insulating-layer-coated mold in which a difference between a thermal expansion coefficient of the heat-insulating layer in contact with the metal layer and a thermal expansion coefficient of the metal layer is 2 × 10 ⁻⁵ / ° C. or less. Molding method. 5. The method according to claim 1, wherein the heat-resistant polymer is dissolved in an organic solvent.
A non-crystalline heat-resistant polymer or polyimide
4. A method for molding a synthetic resin molded article according to 4. 6. The method according to claim 1, wherein the heat-resistant polymer is a linear high molecular weight polymer.
The method for molding a synthetic resin molded article according to claim 4, which is a polyimide. 7. The synthetic resin molding according to claim 4, wherein a difference between a thermal expansion coefficient of the heat insulating layer in contact with the main mold and a thermal expansion coefficient of the main mold is 2 × 10 ⁻⁵ / ° C. or less. Product molding method.