JPH0929753A - Heat insulating layer coated mold for molding synthetic resin - Google Patents

Abstract

PURPOSE: To provide a mold producing a synthetic resin molded product reduced in the conspicuousness of a weld line without requiring post-processing such as painting. CONSTITUTION: A heat insulating layer coated mold for molding a synthetic resin is constituted by providing a heat insulating layer 2 with a thickness of 0.1-0.5mm composed of a heat-resistant polymer on the wall surface constituting the mold cavity of a main mold l composed of a metal and closely bonding metal layers 3, 4 to the heat insulating layer 2 in a thickness of 1-50μm, and 1/5 or less of the thickness of the heat insulating layer 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for molding synthetic resin. More specifically, the present invention relates to a heat insulating layer-covering mold used for injection molding, blow molding, vacuum molding and the like of synthetic resins.

[0002]

2. Description of the Related Art When a thermoplastic resin is injected into a mold cavity for molding, it is necessary to improve reproducibility in imparting a shape condition of a mold surface to a molded product and to improve the appearance of the molded product.
Generally, it can be achieved to some extent by selecting molding conditions such as increasing the resin temperature and the mold temperature, 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, if the mold temperature is raised, the cooling time required for cooling and solidification of the plasticized resin will be longer and the molding efficiency will be lowered. The mold surface reproducibility will be improved without raising the mold temperature, and the mold There is a demand for a method that does not lengthen the required cooling time even if the temperature is increased. Heating and cooling holes are respectively attached to the mold, and a heating medium and a coolant are alternately passed to alternately heat and cool the mold.However, this method consumes a large amount of heat, The cooling time becomes longer.

A mold in which a mold wall forming a mold cavity is coated with a substance having a small thermal conductivity, that is, a heat insulating layer is disclosed in WO 93/06980 and the like. Furthermore, US Pat. No. 3,734,449 and JP-A-53
Japanese Patent No. 86754 discloses a mold in which a metal mold wall surface is covered with a heat insulating layer, and the surface of the heat insulating layer is further covered with a thin metal layer.

[0005]

In recent years, there has been a strong demand for omitting post-processing such as coating on injection molded products and blow molded products of synthetic resins. There is a strong desire to eliminate painting because of reduction in manufacturing costs and reduction of environmental damage due to solvent evaporation during painting. There is a strong demand for omitting post-processing of synthetic resin housings for electrical equipment, electronic equipment, office equipment, etc.

Further, when a polymer is used as the heat insulating layer on the outermost surface of the mold, the heat insulating layer is easily scratched during use, and depending on the type of synthetic resin to be molded, the heat insulating layer may be removed from the mold at the time of molding. Mold release may be difficult, and its improvement is required. As an improved method, it is possible to coat the surface of the heat insulating layer with a thin metal layer. However, there are various problems in the mold in which the thin metal layer is coated on the surface of the heat insulating layer,
The present inventors have found that there are the following problems. That is, if the relationship between the thickness of the metal layer and the thickness of the heat insulating layer is inappropriate, the mold surface reproducibility during molding becomes poor, and if the thickness of the heat insulating layer is increased, the molding cycle time becomes longer and the molding efficiency decreases. It is necessary to solve the problems such as the mold surface reproducibility becomes worse as the metal layer becomes thicker, the adhesion between the metal layer and the heat insulating layer is required, and the surface durability of the metal layer is required.

[0007]

In order to solve these problems, the inventors of the present invention have investigated a mold covered with a heat insulating layer, and have investigated the heat insulating substance for covering the surface of the main mold, its coating state, The present invention was accomplished by examining the combination with the material of the main mold and the metal layer covering the outermost surface.

That is, according to the present invention, a heat insulating layer made of a heat-resistant polymer and having a thickness of 0.1 to 0.5 mm is present on a mold wall forming a mold cavity of a main mold made of metal, and the heat insulating layer is formed on the heat insulating layer. A heat-insulating-layer-coated mold for synthetic resin molding, in which a metal layer having a thickness of 1/5 or less of a layer thickness and a thickness of 1 to 50 μm adhered to the heat insulating layer is present. Further, according to the present invention, when the heated synthetic resin to be molded comes into contact with the mold surface, the mold surface temperature can be raised to a temperature higher than the softening temperature of the synthetic resin by 20 ° C. or more.
The heat-insulating-layer-coated mold for molding the synthetic resin, which has the thicknesses of the heat-insulating layer and the metal layer.

Further, the metal layer is a multilayer of two or more layers, the layer in contact with the heat insulating layer is a chemical nickel plating layer containing phosphorus in an amount of 1% by weight or more and less than 5% by weight, and an electrolytic nickel plating layer is formed thereon. Electrolytic hard chrome plating layer, chemical nickel plating layer containing 5 to 18% by weight of phosphorus, electrolytic copper plating layer,
There is provided the above-mentioned heat-insulating layer-coated mold having at least one layer selected from a chemical copper plating layer and the like. Further, in the method for producing a heat-insulating layer-covering mold in which the heat-insulating layer is polyimide, the surface layer of the heat-insulating layer is a polyimide layer containing calcium carbonate fine powder, and the polyimide layer is finely treated by etching with an acid solution. After forming unevenness, chemical nickel plating is performed at a low temperature and a low speed to form a nickel plating layer on the heat insulating layer, and an electrolytic nickel plating layer, an electrolytic hard chromium plating layer, and phosphorus are added in an amount of 5-18. There is also provided a method for producing a heat-insulating layer-covering mold for molding synthetic resin, which comprises forming at least one layer selected from a chemical nickel plating layer, an electrolytic copper plating layer, a chemical copper plating layer, etc., which is contained by weight.

Hereinafter, the present invention will be described in detail. Synthetic resin molded using the mold of the present invention is a thermoplastic resin that can be used in general injection molding and blow molding, polyethylene, polyolefin such as polypropylene, polystyrene, styrene-acrylonitrile copolymer, rubber reinforced polystyrene, Examples thereof include styrene resins such as ABS resin, polyamide, polyester, polycarbonate, methacrylic resin, vinyl chloride resin and the like. 1-6 for synthetic resin
It preferably contains 0% by weight of resin reinforcement. The resin-reinforced material includes various fibers such as various rubbers, glass fibers, and carbon fibers, and inorganic powders such as talc, calcium carbonate, and kaolin. The mold of the present invention can be used particularly effectively when the content of rubber-reinforced polystyrene and glass fiber is 15
~ 60% by weight of various synthetic resins, nylon 6, nylon 6
Polyamide resins such as 6 and the like, acrylonitrile-styrene copolymers having an acrylonitrile content of 30% by weight or more, ABS resins using the copolymer as a matrix, and the like. When a synthetic resin containing 15 to 60% by weight of glass fiber is injection-molded in a mold in which the wall surface of the mold is covered with a heat-resistant polymer, the heat-insulating layer on the surface of the mold is damaged by the glass fiber. As shown in the present invention, the presence of a metal layer on the surface of the heat insulating layer can prevent damage. Also, polyamide resin,
High acrylonitrile resin and the like generally have poor releasability from the heat insulating layer, and the releasability can be improved by allowing a metal layer to exist on the surface of the heat insulating layer.

Good molded products molded by the mold of the present invention are generally used synthetic resin injection molded products such as housings for light electric appliances, electronic devices, office equipment, various automobile parts, various daily necessities, various industrial parts, etc. Is. Particularly preferred are housings of electronic equipment, electric equipment, office equipment, etc., which have many weld lines. These injection-molded articles are molded by a general injection molding method, but particularly when used in combination with low-pressure injection molding such as gas-assisted injection molding and injection compression molding, the effect is great. Further, good molded products molded by the mold of the present invention are various blow molded products that are required to have an appearance.

The main mold made of metal described in the present invention is
Metal molds generally used for molding synthetic resins, such as iron or steel materials containing iron as a main component, aluminum or alloys containing aluminum as a main component, zinc alloys such as ZAS, and beryllium-copper alloys are included. 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 hard chromium, nickel, or the like.

The metal used for the metal layer coated on the surface of the heat insulating layer of the mold used in the present invention is a metal generally used for metal plating, and is at least one of chromium, nickel, copper and the like. . Chemical nickel plating, electrolytic nickel plating, chemical copper plating, electrolytic copper plating, and electrolytic chromium plating can be preferably used. The metal layer is coated on the surface of the heat insulating layer. The heat insulating layer and the metal layer need to be in close contact with each other, and the layer in contact with the heat insulating layer is particularly preferably a chemical nickel plating layer having an appropriate phosphorus content.

The metal layer closely adhered to the heat insulating layer described in the present invention means that the heat insulating layer and the metal layer do not separate from each other in a cooling / heating cycle caused by molding such as injection molding of synthetic resin over 10,000 times. The thickness of the metal layer is ⅕ or less of the thickness of the heat insulating layer and 1 to 50 μm, preferably 1/7 or less and 2 to 30 μm, and more preferably 1/10.
˜1 / 100 and 2˜30 μm. When the surface of the heat insulation layer and / or the surface of the metal layer has a matte or grain-like unevenness, the average thickness is taken as the thickness of each layer. That is, JI
The thickness of the average line measured by SB0601 is defined as the average thickness. If the metal layer is too thick, the effect of coating the heat insulating layer on the surface of the main mold is lost, and the mold surface reproducibility deteriorates.

The total thickness of the metal layer is preferably uniform, and the variation in thickness is preferably ± 10% or less.
More preferably, it is ± 5% or less. If the variation of the metal layer thickness is large, the mold surface reproducibility of the portion where the metal layer thickness is large deteriorates, and a portion having good mold surface reproducibility and a portion having poor mold surface reproducibility appear on the same molded product surface, which is not preferable. When the surface of the metal layer is uneven in a grain shape, the thickness of the metal layer of the convex portion or the thickness of the metal layer of the concave portion is preferably uniform, and the variation in each thickness is preferably ± 10% or less, More preferably, it is ± 5% or less.

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 or less.
It is a heat resistant polymer having a temperature of 40 ° C. or higher, preferably 160 ° C. or higher, more preferably 200 ° C. or higher, and / or a melting point of 200 ° C. or higher, more preferably 250 ° C. or higher. The heat conductivity of the heat resistant polymer is generally 0.0001 to 0.002 ca.
1 / cm · sec · ° C, which is significantly smaller than metal.
Further, a tough polymer having a breaking elongation of 5% or more, preferably 10% or more is preferable for the heat resistant polymer. 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 favorably used as the heat insulating layer in the present invention are heat resistant polymers having an aromatic ring in the main chain, and examples thereof include various amorphous heat resistant polymers soluble in organic solvents and various polyimides. It can be used well. As the non-crystalline heat-resistant polymer, polysulfone, polyether sulfone,
And polyetherimide. These amorphous heat-resistant polymers can be used as the heat-insulating layer of the present invention by lowering the coefficient of thermal expansion by adding a filler such as carbon fiber. 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.

Further, in the present invention, an epoxy resin having a small coefficient of thermal expansion, that is, an epoxy resin cured product obtained by combining an epoxy resin having a small coefficient of thermal expansion and a curing agent, or an epoxy resin containing various fillers in an appropriate amount can be used. (Hereinafter, the cured epoxy resin is abbreviated as epoxy resin.). Epoxy resins generally have a large coefficient of thermal expansion, and the difference in coefficient of thermal expansion from a metal mold is large. However, glass, silica, talc, clay, zirconium silicate, lithium silicate, calcium carbonate, alumina, which have a small coefficient of thermal expansion,
Powder and particles such as mica, glass fiber, whiskers, carbon fiber, etc. are mixed in an appropriate amount with an epoxy resin, and a filler-containing epoxy resin with a small difference in thermal expansion coefficient from the metal mold is used as the heat insulating layer of the present invention. It can be used well.

Further, in addition to the epoxy resin or the epoxy resin containing a filler, a tough thermoplastic resin such as nylon,
A compounded epoxy resin to which toughness is imparted by adding various compounds such as rubber that impart toughness can also be used favorably. In particular, a polymer alloy obtained by blending an epoxy resin with polyether sulfone or polyether imide and curing it has excellent toughness and can be used favorably.

In injection molding, blow molding, etc., the mold surface that comes into contact with the heated resin to be molded is exposed to a strict cooling / heating cycle for each molding. Further, 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 of the heat insulating layer and that of the metal layer are largely different. Stress is repeatedly generated and peeling occurs at the interface. By reducing the difference between the coefficient of thermal expansion of the main mold and / or the metal layer in contact with the heat insulating layer and the coefficient of thermal expansion of the heat insulating layer, it is possible to reduce the stress that causes peeling. In the present invention, the difference between the coefficient of thermal expansion of the main mold and / or the metal layer in contact with the heat insulating layer and the coefficient of thermal expansion of the heat insulating layer is preferably less than 4 × 10 ⁻⁵ / ° C., and more preferably 3 × 10 ⁻⁵ / ° C. Less than ^-5 / ° C. In general, metals have a lower coefficient of thermal expansion than polymers, and it is therefore preferable to select a heat-resistant polymer having a smaller coefficient of thermal expansion.

The coefficient of thermal expansion described here is a coefficient of linear expansion. The thermal expansion coefficient of the heat insulating layer is a linear expansion coefficient in the surface direction of the heat insulating layer, and is measured by the method shown in JIS K7197-1991, and is the average value between the temperatures of 50 ° C. and 250 ° C., or the glass transition temperature of the heat insulating layer. If the temperature is below 250 ℃,
It is shown as an average value between 50 ° C. and the glass transition temperature. That is, a heat insulating layer is formed on a smooth flat metal, and then the heat insulating layer is peeled off, and the heat insulating layer is heated between 50 ° C. and 250 ° C.
Alternatively, the average coefficient of thermal expansion between 50 ° C and the glass transition temperature is measured.

In the present invention, a mold comprising two or more heat insulating layers can be favorably used. In this case, it is preferable that at least the difference between the coefficient of thermal expansion of the main mold and / or the metal layer in contact with the heat insulating layer and the coefficient of thermal expansion of the heat insulating layer is small, 4 × 10 ⁻⁵ /
It is preferably less than ℃, more preferably 3 × 10
^-5 / ° C. When coating the main mold with a heat insulating layer and metal,
Alternatively, when injection molding or the like is performed with the mold of the present invention, the most intense stress occurs at the interface between the metal layer and the heat insulating layer. The stress generated can be reduced by selecting and using a material having a thermal expansion coefficient close to both layers forming the interface.

The cause of the peeling between the heat insulating layer and the main mold or between the heat insulating layer and the metal layer is not only the difference in the coefficient of thermal expansion.
However, the difference in the coefficient of thermal expansion is an extremely large factor. If the heat insulating layer is a so-called rubber-like heat insulating layer having a large adhesive force between the heat insulating layer and the main mold and / or the metal layer, a small tensile elastic modulus of the heat insulating layer, and a large breaking elongation, Peeling does not occur even if the difference is slightly large. 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, which has a large elastic modulus.
Alternatively, it is preferable that the difference in the coefficient of thermal expansion is small in order to bring the metal layer into close contact with the metal layer and prevent peeling.

When the wall surface of the mold 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, 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 is difficult to obtain a polymer satisfying all of these properties, and thus it is preferable to use two or more heat insulating layers.
Table 1 shows the thermal expansion coefficients of the metal of the main mold and the metal layer covering the outermost surface, the heat-resistant polymer of the heat insulating layer, and general synthetic resins that can be favorably used in the present invention.

[0025]

[Table 1]

If the coefficient of thermal expansion of the main mold and / or the metal layer is increased, a heat insulating layer having a relatively large coefficient of thermal expansion can be used. Steel is most often used as a mold material, but recently aluminum alloys and zinc alloys have also been used. In the present invention, it is preferable that the thermal expansion coefficient is as close as possible. When steel is used for the main mold, a low thermal expansion type polyimide or the like having an extremely small thermal expansion coefficient can be used favorably. Table 2 shows the thermal expansion coefficients of various low thermal expansion polyimides.

[0027]

[Table 2]

In the table, Bifix and Free did not allow the film to shrink freely when the polyimide precursor was imidized to form a polyimide film (Fre).
e) Is the polymer chain fixed in a square frame to suppress the shrinkage that occurs during imidization and to cause the polymer chains to be in-plane oriented by the stress (Bi
fix). 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.

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

[0030]

[Table 3]

Injection molding has an economic value in that a molded product having a complicated shape can be obtained by molding once. In order to coat the complex mold surface with a heat-resistant polymer and make it adhere tightly, a heat-resistant polymer solution and / or a heat-resistant polymer precursor solution is applied, and then heated to heat-resistant polymer. It is most preferable to form a united heat insulating layer. Therefore, it is preferable that the heat resistant polymer or the heat resistant polymer precursor of the present invention 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. Chemical formula 1 shows a reaction formula for forming a polyimide from a polyamic acid.

[0032]

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When a polyamic acid solution of a polyimide precursor is applied to the mold wall surface and then heated and cured to form a polyimide, the glass transition temperature and the coefficient of thermal expansion of the polyimide may vary depending on the heating and curing temperature and / or the heating and curing atmosphere. different. Generally, the higher the heating and curing temperature, the higher the glass transition temperature and the smaller the coefficient of thermal expansion. Generally, when the temperature of the polyamic acid is 250 ° C. or higher, imidization progresses to almost 100% to form a polyimide, and it is considered that the movement of molecules after becoming a polyimide affects the coefficient of thermal expansion.

It is necessary that the heat-insulating layer of the present invention and the main mold and / or the heat-insulating layer and the metal layer have a high adhesion, and the width at room temperature is preferably 0.5 kg / 10 mm or more, more preferably 0. 8kg / 10mm width or more, most preferably 1k
g / 10 mm width or more. This is the peeling force when the metal layer or the heat-insulating layer or the metal layer in contact with each other is cut to a width of 10 mm and pulled at a speed of 20 mm / min in a direction perpendicular to the bonding surface. This peeling force varies considerably depending on the measurement location and the number of measurements, but it is important that the minimum value is large.
A stable and large peeling force is preferable. 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. As a preferable example of the primer treatment, a polyimide containing a large amount of CO ₂ group or SO ₂ group easily adheres to the surface of the metal mold, and a thin layer of polyimide having excellent adhesion is used as a primer layer. Can be favorably used.

Injection molding has the greatest merit that a mold having a complicated shape can be formed by molding once, and therefore, the mold cavity generally has a complicated shape. However, it is extremely difficult to apply a coating substance to the surface of this complex-shaped mold cavity in a mirror-like manner.Therefore, the applied coating layer is polished later, and the coating layer is numerically controlled by a numerical control milling machine. The best method is to grind the surface after polishing with a control machine tool and finish it to a mirror surface.

In the present invention, the total thickness of the heat insulating layer is 0.1 mm.
It is necessary to select an appropriate value within a very narrow range of 0.5 mm, preferably 0.15 to 0.45 mm, in order to balance appearance improvement and molding cycle time. Preferably, it is 0.1 mm to 0.3 mm in injection molding and 0.3 mm to 0.5 mm in blow molding.
With a thin heat insulating layer of less than 0.1 mm, the effect of improving the appearance of the molded product is small. If the thickness of the heat insulating layer exceeds 0.5 mm, the cooling time in the mold becomes long, which is not preferable from an economical point of view.

In molding a thermoplastic resin, the mold temperature and the molding cycle time are closely related. That is, the relationship between the mold temperature (Td) and the required cooling time (θ) in the mold during molding is theoretically expressed by the following equation. θ = − (D ² / 2πα) · ln [(π / 4) {(Tx−
Td) / (Tc−Td)｝] θ: Cooling time (sec) D: Maximum thickness of molded article (cm) Tc: Cylinder temperature (° C) Tx: Softening temperature of molded article (° C) α: Heat of resin Diffusivity Td: Mold temperature (° C) Cooling time (θ) is proportional to the square of the molded product thickness (D),
It is a function of the (Tx-Td) value. That is, it is a function of the value obtained by subtracting the mold temperature from the softening temperature of the synthetic resin. When this value is small, a change in this value causes a large change in the cooling time. However, when this value is large, a change in the cooling time becomes small.

Covering the main mold with a heat-insulating layer functions in the same way as increasing the thickness of the molded product and lengthening the cooling time, while decreasing the mold temperature shortens the cooling time. Work towards. It is preferable from the viewpoint of the molding cycle time that the thickness of the heat insulating layer is thin and the appearance can be improved. When the surface of the main mold made of metal is covered with a heat insulating layer and the heated synthetic resin injected onto the surface contacts, the surface of the mold is heated by the heat of the resin. The smaller the thermal conductivity of the heat insulating layer, the more
The thicker the heat insulating layer, the higher the mold surface temperature.

In the present invention, the heat insulating layer and the metal layer have a thickness capable of raising the mold surface temperature to a temperature higher than the softening temperature of the synthetic resin by 20 ° C. or more when the molded synthetic resin comes into contact with the mold surface. It is a mold. The mold surface temperature is an interface temperature at which the heated synthetic resin to be molded comes into contact, and the mold surface temperature and the resin surface temperature are equal. In the present invention, the mold surface temperature and the resin surface temperature have the same meaning. When the heat-plasticized synthetic resin comes into contact with the cooled mold of the present invention, heat is taken by the metal layer having a large heat capacity, and the mold surface temperature temporarily decreases, but immediately rises to soften the synthetic resin. It rises above the temperature and then falls again. The mold surface temperature which is raised in the present invention refers to the maximum temperature of the temperature which is once lowered and then immediately raised. The temperature to be raised depends on the temperature of the main mold, the temperature of the synthetic resin to be molded, the thermal conductivity of each material, and the like. Generally, the temperature of the main mold is room temperature to (softening temperature of synthetic resin −20 ° C.), and the temperature of synthetic resin is 190 to 300 ° C., which is also used in the present invention.

When the heated synthetic resin to be molded comes into contact with the mold surface, if the mold surface temperature is raised to 20 ° C. or more, preferably 25 ° C. or more higher than the softening temperature of the synthetic resin, the mold surface reproducibility of the molded product is improved. In the present invention, the thicknesses of the heat insulating layer and the metal layer are selected so that the temperature can be raised to 20 ° C. or higher, preferably 25 ° C. or higher, since the temperature is significantly improved. However, the choice is that the thickness of the heat insulating layer is 0.1-0.5 mm. The thickness of the metal layer is ⅕ or less of the thickness of the heat insulating layer and is selected from the range of 1 to 50 μm.

The softening temperature of the synthetic resin described here is the temperature at which the synthetic resin can be easily deformed. For the amorphous resin, the Vicat softening temperature (ASTM D1525), and for the hard crystalline resin, the heat deformation temperature (ASTM D648 load). 1
8.6 kg / cm ² ), and the temperature for soft crystalline resin is indicated by the heat distortion temperature (4.6 kg / cm ² under ASTM D648 load). 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.

The change in mold surface temperature during injection molding can be calculated from the temperatures of the synthetic resin, the main mold, the heat insulating layer, specific heat, thermal conductivity, density, latent heat of crystallization and the like. 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 surface of the heat insulating layer described in the present invention is substantially smooth, or has fine irregularities for enhancing the adhesion with the metal layer, grain-like shapes and the like.

The metal layer of the present invention is in close contact with the heat insulating layer.
The adhesion of the metal layer is preferably 300 g / 10 mm width or more, more preferably 400 g / 10 mm width or more, and most preferably 500 g / 10 mm width or more. The adhesive force is a peeling force when the adhered metal layer is cut into a width of 10 mm and pulled in a direction perpendicular to the adhered surface at a speed of 20 mm / min.

The metal layer of the present invention can be coated by various methods, but is well coated by plating. The plating described here is chemical plating and electrolytic plating. Generally, plating is performed through some of the following steps. That is, first, chemical plating is performed in contact with the heat insulating layer. Pretreatment (deburring, degreasing) → chemical corrosion (chemical etching with acid or alkali:
Make the surface moderately uneven) → Neutralize → Sensitize (Synthetic resin surface adsorbs a reducing metal salt to show activation effect) → Activate (catalytic precious metal such as palladium) Chemical plating (chemical nickel plating, chemical copper plating, etc.) → electrolytic plating (electrolytic nickel plating, electrolytic copper plating, electrolytic chrome plating, etc.) (For details, see “Plastic plating” by Romo Tatsumi, 1974. Year, see the Nikkan Kogyo Shimbun, etc.).

Chemical plating is a method of reducing and depositing metal ions on a metal with a reducing agent. In general, chemical plating needs to satisfy the following conditions. (1) The reducing agent is stable without self-decomposition while the plating solution is adjusted. (2) The product after the reduction reaction does not cause precipitation. (3) The precipitation rate can be controlled by adjusting the pH and the liquid temperature. In chemical nickel plating, hypophosphorous acid, hydroboric acid, etc. are used as a reducing agent, and hypophosphorous acid is particularly preferably used. In order to satisfy the above conditions, auxiliary components (pH adjuster, buffer, accelerator, stabilizer, etc.) are added to the chemical plating solution in addition to the main components (metal salt, reducing agent).

A preferred chemical nickel plating layer which adheres to the heat insulating layer of the present invention contains phosphorus in an amount of 1% by weight or more and less than 5% by weight, more preferably 2% by weight or more and less than 5% by weight. The thickness of the chemical nickel plating layer is sufficient as a layer called a primer, preferably 0.1 to 5
μm, more preferably about 0.2 to 2 μm. In the chemical nickel plating used in the present invention, hypophosphorous acid is used as a reducing agent together with various auxiliary components, and the resulting nickel plating contains phosphorus. In the heat insulating layer-coated mold of the present invention, it is necessary to firmly adhere the chemical nickel plating layer to the heat insulating layer. Therefore, in the initial stage of the chemical nickel plating, the temperature of the plating solution is lowered and the pH is adjusted to adjust the plating. It is highly preferable to reduce the speed and to generate plated particles of small size. After the plating layer having a constant thickness is formed, the plating speed is increased to perform the plating efficiently. As a result, the nickel plating layer in contact with the heat insulating layer becomes a nickel plating layer containing phosphorus in an amount of 1% by weight or more and less than 5% by weight, and the plating layer thereon has an electrolytic nickel plating layer, an electrolytic chrome plating layer, or phosphorus of 5% by weight. ~ 18% by weight
It becomes a chemical nickel plating layer etc. to be contained. If the surface of the heat insulating layer is directly subjected to chemical nickel plating containing a large amount of phosphorus, particularly chemical nickel plating containing 8% by weight or more of phosphorus, the size of nickel particles will increase and the adhesion of the plating layer will decrease, which is not preferable. The phosphorus content is determined by the usual elemental analysis method for metals.

In order to increase the adhesion between the heat insulating layer and the plating layer, powder of calcium carbonate or silicon oxide is mixed with the heat insulating material forming the outermost surface of the heat insulating layer, and the powder is melted by chemical corrosion to bring the surface to an appropriate level. It can be used very well if it is made to have irregularities. The metal plating on the surface of the polyimide layer most suitable as the heat insulating layer of the present invention will be described in detail. The metal plating on the surface of the polyimide starts with making the surface have a suitable unevenness. As this method, US Pat.
As shown in US Pat. No. 449, US Pat. No. 4,842,946, etc., it is common to treat the surface of the polyimide with an alkali to form fine irregularities on the surface. That is, polyimide is weak against alkali, and its surface becomes a kind of swelling state by the alkali treatment, and is likely to have fine irregularities. However, since the metal layer on the surface of the heat insulating layer is exposed to severe cooling and heating cycles during molding of the synthetic resin, it is difficult to obtain sufficient adhesion strength to withstand the severe cooling and heating cycle by simply treating the polyimide surface with alkali. The polyimide surface layer is coated with polyimide mixed with calcium carbonate fine powder, and the surface is etched with an acid solution to elute part of the calcium carbonate fine powder to make the surface of the polyimide layer uneven, and then chemical nickel plating. The inventors have found that the method of carrying out the method can be used particularly well in the present invention.

Specific examples that can be favorably used in the present invention are shown below in more detail. Fine calcium carbonate fine powder having an average particle size of 0.005 to 1 μm, preferably 0.05 to 0.5 μm, is compounded in an amount of 3 to 30% by weight, preferably 5 to 20% by weight, based on the solid content of polyimide, A polyimide surface layer is obtained by sufficiently kneading with polyimide and coating with polyimide. The thickness of the surface layer is preferably 1 to 30 μm, more preferably 5 to 20 μm. The calcium carbonate fine particles easily aggregate, and they are well kneaded with the polyimide precursor solution to be sufficiently dispersed, and this is applied to the surface of the polyimide heat insulating layer of the mold, and heated to form a polyimide. Then, the polyimide surface is subjected to etching treatment with an acid solution to elute a part of the calcium carbonate fine particles to form fine irregularities on the polyimide surface, and then chemical nickel plating is performed using sodium hypophosphite as a reducing agent. Chemical nickel plating is performed at a low temperature and low alkaline condition at low speed to reduce the size of the nickel particles that are generated, and to form nickel plating that evenly enters nickel into the fine irregularities on the surface of the polyimide layer, thereby ensuring close contact. A method of significantly increasing the force is a highly preferred method for the present invention. Generally, chemical nickel plating is performed in an acidic state by raising the temperature and improving plating efficiency. When sodium hypophosphite is used as a reducing agent and chemical nickel plating is performed at low temperature and low speed in a weak alkaline state, the phosphorus content in the nickel plating becomes 1% by weight or more and less than 5% by weight. Therefore, the preferable composition of the chemical nickel plating layer in contact with the heat insulation layer of the present invention contains 1% by weight or more and less than 5% by weight of phosphorus.

"Chemical nickel plating described in the present invention at low temperature and low speed" means lower temperature and lower speed than generally used chemical nickel plating, but preferably 50.
℃ or less 5 ℃ or more, more preferably 40 ℃ or less 10 ℃ or more temperature, preferably 10μm / hour or less 0.5μ
The speed is at least m / hour. Various plating layers can be provided on the thin chemical nickel plating that firmly adheres to the heat insulating layer. Preferred specific examples of the plating further applied on the thin chemical nickel plating are as follows. (1) Chemical nickel plating (containing 5 to 18% by weight of phosphorus) (2) Electrolytic chromium plating (3) Electrolytic nickel plating (sulfur content is 0.0005)
% Or less) → Electrolytic nickel plating (sulfur content is 0.
(005 to 0.2% by weight) (4) Chemical copper plating (5) Electrolytic copper plating At least one layer selected from these platings is coated.

The surface of the metal layer of the mold of the present invention may be mirror-like, matte or grain-like, and is appropriately selected. Various methods can be used to make the surface of the metal layer formed by plating into a grain shape. The etching method can be used favorably. The acid etching method is best used. If the outermost surface layer of the mold is a metal that can be etched with an acid solution such as electrolytic nickel plating or electrolytic copper plating, it can be grained by the same method as a general metal mold etching method. That is, a method in which the surface of the metal layer is masked with an ultraviolet curable resin in a grain shape and then grained by acid etching can be favorably used. When the metal layer is nickel plated, the chemical nickel plating having a phosphorus content of 8% by weight or more is difficult to be etched by an acid, and the chemical nickel plating having a phosphorus content less than that is easily etched.

For the phosphorus content and acid resistance of the chemical nickel plating, see Plating and Surface F.
inishing, 79, No. 3, p. 29-33
(1992), the higher the phosphorus content, the better the acid resistance. In Table 1 of the above document, the acid resistance is Good when the phosphorus content is 10 to 12% by weight, and Fa when the phosphorus content is 7 to 9% by weight.
Ir is 1 to 4% by weight and becomes Poor. The phase diagram of the nickel-phosphorus alloy shows that the phosphorus content is 0-4.5% by weight.
Phase 11 to 15 wt% is the γ phase and 4.5 to 11 wt% is the mixture of the γ and β phases. Corrosion resistance to acid is γ
8% by weight, which is generally said to have a high phosphorus content and has an excellent phase
In the above cases, the corrosion resistance is great.

In the electrolytic nickel plating, the sulfur content is low (generally 0.0005% by weight or less). The semi-bright nickel plating is difficult to be etched by acid, and the sulfur content is high (generally 0.005% by weight or more). Nickel plating is susceptible to acid etching. In order to make the surface of the mold grain-shaped, the surface of the metal layer is made a metal layer which is easily etched, and is acid-etched to be grain-shaped. The grain depth due to etching can be adjusted by adjusting the etching time, combining a metal layer that is easily etched and a metal layer that is difficult to be etched, and the like. After forming the grained surface, it is necessary to attach a metal layer with excellent corrosion resistance, that is, a chemical nickel plating layer with a high phosphorus content, an electrolytic hard chrome plating layer, etc., to the outermost surface of the metallized surface of the metal layer using a mold. It can be used well to prevent corrosion inside.

The present invention will be described with reference to the drawings. 1 to 3 are sectional views showing the vicinity of the mold surface of the synthetic resin molding mold of the present invention. In FIG. 1, the main wall of the main mold 1 made of a metal has a wall surface of the mold forming the mold cavity of 0.
The heat insulating layer 2 having a thickness of 1 to 0.5 mm is present, and the metal layers 3 and 4 adhered to the heat insulating layer are present thereon, and the metal layer thickness B is 1/5 or less of the heat insulating layer thickness A, and 1 ˜50 μm, preferably 1/7 or less, and 2 to 30 μm, more preferably 1/10 to 1/100 and 2 to 30 μm. The metal layer needs to be firmly adhered to the heat insulating layer, and in order to achieve this, the metal layer is preferably a multilayer of two or more layers. The preferred layer structure is the heat insulating layer 2
The metal layer in contact with is the first layer 3 composed of a chemical nickel plating layer containing phosphorus in an amount of 1% by weight or more and less than 5% by weight,
A metal layer on which a second layer 4 selected from an electrolytic nickel plating layer, an electrolytic hard chromium plating layer, and a chemical nickel plating layer containing 5 to 18% by weight of phosphorus is present.

FIG. 2 shows the case where the number of metal layers is three. The metal layer in contact with the heat insulating layer 2 is the first metal layer 3 composed of a chemical nickel plating layer containing 1 wt% or more and less than 5 wt% of phosphorus, and a chemical nickel plating containing 5 to 18 wt% of phosphorus thereon. It is a metal layer having a three-layer structure in which a second metal layer 4 made of a layer and a third metal layer 5 made of an electrolytic hard chrome plating layer are further present thereon. The thickness B of the metal layer is ⅕ or less of the thickness A of the heat insulating layer and 1 to 50 μm, preferably 1/7 or less and 2 to 30 μm, more preferably 1 / m.
The thickness is 10 to 1/100 and 2 to 30 μm.

FIG. 3 shows a three-layer metal layer having a metal layer surface 6 having a grain shape. The metal layer in contact with the heat insulating layer 2 contains 1 phosphorus.
A first metal layer 3 consisting of a chemical nickel plating layer containing at least 5% by weight and less than 5% by weight, on which an electrolytic nickel plating layer having a large sulfur content (generally 0.005% by weight or more), electrolytic copper plating There is a second metal layer 4 composed of a layer or the like, and the second metal layer is formed into a grain shape by acid etching, and a metal layer having excellent corrosion resistance is formed thereon, for example, a chemical nickel plating layer having a high phosphorus content, or an electrolytic hard layer. A third metal layer 5 made of a chrome plating layer or the like is attached to the mold of the present invention.
It is preferable that an electrolytic nickel plating layer having a low sulfur content (generally 0.0005% by weight or less) is further present between the first metal layer 3 and the second metal layer 4. When the metal layer is uneven like a grain, the average thickness is defined as the metal layer thickness.

In FIGS. 4, 5 and 6, the temperature of the main mold made of steel is 50.degree. C. and the temperature of the rubber reinforced polystyrene is 2.
The calculated value of the change in temperature distribution near the mold wall surface when injection molding is performed at 40 ° C is shown. The numerical value of each curve in the figure indicates the time (seconds) after the heated synthetic resin comes into contact with the cooled mold wall. The heated synthetic resin comes into contact with the mold wall surface and is rapidly cooled (FIG. 4). When the main mold surface is covered with a heat insulating layer, the mold surface receives heat from the heated synthetic resin and rises in temperature. As shown in the figure, the mold surface is 0.1m
When coated with a heat insulating layer (polyimide) of m and 0.5 mm (FIGS. 5 and 6), the temperature rise of the surface of the heat insulating layer in contact with the synthetic resin increases and the temperature decreasing rate also decreases.

7, FIG. 8, FIG. 9, FIG. 10, FIG. 11 and FIG. 12 are compared with a mold in which the surface of the main mold made of steel is coated with a polyimide layer and the surface is coated with a nickel layer. When a mold coated only with a polyimide layer is used, the temperature of the main mold is set to 50 ° C., and when the temperature of the rubber-reinforced polystyrene resin is injection molded at 240 ° C. The change with time of the temperature of the resin surface (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) after contact with the surface is shown.

FIG. 7 shows the resin surface temperature with time when the thickness of the polyimide (hereinafter referred to as PI in the figure) layer is 0.30 mm and the thickness of the nickel (hereinafter referred to as Ni in the figure) layer is 0.02 mm. Show changes. 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 in which the temperature once drops increases, and the temperature in which the temperature rises again decreases. It is preferable that the mold surface temperature is once greatly decreased and then immediately raised, and the raised maximum temperature is 20 ° C. or higher, more preferably 25 ° C. or higher, than the softening temperature of the synthetic resin to be molded.

FIG. 8 shows a case in which the thickness of the nickel layer is as thick as 0.1 mm. When the thickness of the nickel layer becomes thick, the temperature range that once drops is large and the temperature that rises again becomes low. Such a combination of the thickness of the heat insulating layer and the thickness of the metal layer is not included in the present invention. 9 and 10 show the case where the thickness of the polyimide layer is 0.15 mm with the same layer configuration as in FIGS. 7 and 8.
Even when the thickness of the polyimide layer is 0.15 mm, the same tendency as in FIGS. 7 and 8 is observed.

11 and 12 collectively show the results of FIGS. 7 to 10. From FIG. 11 and FIG. 12, in the case of this metal mold coated with a nickel layer, when the thickness of the nickel layer becomes 0.1 mm, the surface temperature once lowered once rises again and the temperature becomes lower. The surface reproducibility is deteriorated and is not included in the present invention. When the thickness of the nickel layer is 0.02 mm, the resin surface temperature recovers rapidly even if it drops once, and since the temperature is high, the mold surface reproducibility during injection molding is good. From these facts, the thickness of the metal layer coated on the surface of the heat insulating layer is limited in order to improve mold surface reproducibility, and the present invention shows a mold for molding in which the appearance of the molded product is particularly required. Accordingly, the present invention provides a mold for forming a molded product having a good appearance by reducing the thickness of the metal layer.

The change of the mold surface temperature at the time of injection molding shown in the figure can be calculated from the temperature of the synthetic resin, the main mold, the heat insulating layer, the specific heat, the thermal conductivity, the density, the latent heat of crystallization and the like. For example, AD
Using INA and ADINAT (software developed at Massachusetts Institute of Technology) and the like, it is possible to calculate by unsteady heat conduction analysis by the nonlinear finite element method, and the temperature shown in the figure is also calculated by it.

By using the mold of the present invention, the conspicuousness of the weld line of the synthetic resin molded product can be reduced, the reproducibility of the mold surface can be improved, and post-processing performed after molding can be omitted.
Compared with the case of using a mold with the outermost surface of the mold being a heat insulating layer, scratches on the mold surface during molding can be reduced, mold release properties can be improved, and long-term molding It is possible to improve the durability of the mold, especially the durability of the part having a small draft.

[0063]

EXAMPLE The following main mold, heat insulating layer and metal layer are used. Main mold: A steel (S55C) mold for injection molding. The coefficient of thermal expansion of the mold is 1.1 × 10 ^-5 / ° C.
It has a mold cavity for the molded product 7 shown in FIG. The molded product has a size of 100 mm × 100 mm and a thickness of 2 mm, and has a hole 8 of 30 mm × 30 mm in the center. The gate 9 is a side gate as shown in FIG. 13, and a weld line 10 is generated in the molded product 7. The mold surface is mirror-like. Five inserts forming the mold cavity of this main mold are prepared, and the surface of each insert is plated with hard chrome. Insulation layer: Prime the inner mold surface of the main mold. As a primer, a polyimide precursor solution containing a large amount of CO ₂ groups is applied to a thin layer and heated to form a polyimide thin layer, which is used as a primer. A polyimide varnish "Treney # 3000" (manufactured by Toray Industries, Inc.) was applied on top of it, and 16
Heat at 0 ° C., and then repeat this coating and heating to a predetermined thickness, and finally mix calcium carbonate fine powder having an average particle size of 0.08 μm in a solid content ratio of 11% by weight and thoroughly kneading. A thin layer of the above polyimide varnish is coated only on the outermost surface of the heat insulating layer and then heated to 290 ° C. to form a polyimide layer. The coefficient of thermal expansion of the polyimide is 3.3 × 1
0 ^-5 / ° C. Metal layer A: Chemical nickel plating having a phosphorus content of 3 to 4% by weight, which was formed by performing chemical nickel plating at a low temperature of 35 ° C. in a weak alkaline state and at a low speed using sodium hypophosphite as a reducing agent. Metal layer B: Chemical nickel plating having a phosphorus content of 5 to 7% by weight, which is formed by performing chemical nickel plating at a high temperature in an acidic state at a high speed using sodium hypophosphite as a reducing agent. Metal layer C: Electrolytic nickel plating with a sulfur content of 0.005% by weight (phosphorus is not included). Metal layer D: Chemical nickel plating having a phosphorus content of 9% by weight, which was formed by performing chemical nickel plating at a high temperature in an acidic state at a high speed using sodium hypophosphite as a reducing agent. Metal layer E: Electrolytic nickel plating with a sulfur content of 0.0005% by weight (phosphorus is not included). The coefficient of thermal expansion of each nickel plating layer is approximately 1.3 × 10 -5 /
° C. First metal layer: The surface of the heat insulating layer is etched with an acid solution to form fine irregularities, and then processed in the order of neutralization → sensitization treatment → activation treatment, and then the metal layer A is chemically nickel plated. Graining of the metal surface: The metal layer C is grained in the steps of coating a photosensitive resin, masking a grain pattern, irradiating with ultraviolet rays, washing, and etching with an acid solution. Thermoplastic resin for injection molding: Rubber-reinforced polystyrene resin "Asahi Kasei Polystyrene 492" (manufactured by Asahi Kasei Kogyo Co., Ltd.)

[0064]

Example 1 A surface of a heat insulating layer of a main mold coated with a heat insulating layer of 200 μm was coated with a first metal layer of a metal layer A having a thickness of 0.5 μm, and a metal layer B of 5 μm was coated on the surface thereof. Further, the surface thereof is coated with a metal layer D having a thickness of 5 μm. 50 this mold
At 240 ° C., the thermoplastic resin is injection-molded at 240 ° C. The metal layer and the heat insulating layer are firmly adhered to each other, and no separation occurs after 10,000 injection moldings. The molded product has no visible weld line and has a good appearance.

[0065]

Example 2 The surface of the heat-insulating layer of the main mold coated with the heat-insulating layer of 200 μm was coated with the first metal layer of 0.5 μm in thickness of the metal layer A, and the surface thereof was coated with the metal layer B of 5 μm, Further, the surface thereof is coated with a metal layer C having a thickness of 15 μm. Next, the metal layer C is etched to a depth of 10 μm to form a grain surface. Further, the grainy surface is coated with a metal layer D having a thickness of 2 μm. The average thickness of the entire metal layer is 15 μm. This mold is set at 50 ° C., and thermoplastic resin injection molding is performed at 240 ° C. The metal layer and the heat insulating layer are firmly adhered to each other, and no separation occurs after 10,000 injection moldings. The molded product has no noticeable weld line and has an excellent grain-like surface.

[0066]

Third Embodiment A metal layer E is used instead of the metal layer B of the second embodiment, and the same operation as in the second embodiment is performed. The metal layer and the heat insulating layer are firmly adhered to each other, and no separation occurs after 10,000 injection moldings. The molded product has no noticeable weld line and has an excellent grain-like surface.

[0067]

Comparative Example 1 The surface of the heat insulating layer of the main mold coated with the heat insulating layer of 700 μm is covered with the first metal layer of the metal layer A having a thickness of 0.5 μm, and the surface thereof is covered with the metal layer B of 5 μm, Further, the surface thereof is coated with a metal layer D having a thickness of 5 μm. Injection molding of a thermoplastic resin is performed using this mold. Molded products have no noticeable weld lines and good gloss, but the molding cycle time is long and molding efficiency is poor.

[0068]

Comparative Example 2 The surface of the heat insulating layer of the main mold coated with the heat insulating layer of 200 μm is coated with the first metal layer of 0.5 μm in thickness of the metal layer A, and the surface thereof is coated with the metal layer B of 5 μm, Further, the surface thereof is coated with a metal layer C having a thickness of 50 μm. Next, the metal layer C is etched to a depth of 30 μm to form a grain surface. Further, this surface is coated with a metal layer D having a thickness of 2 μm. The average thickness of the metal layer is 45 μm. Injection molding of a thermoplastic resin is performed using this mold. The molded product will be one with a conspicuous weld line.

[0069]

EFFECTS OF THE INVENTION A molded article having a good appearance is obtained by injection molding or blow molding a synthetic resin using the heat insulating layer-coated mold of the present invention. In particular, by using the mold of the present invention, it is possible to reduce the conspicuousness of the weld line for injection-molded products such as housings for light electrical equipment and office equipment that have conventionally required a large number of weld lines and require post-processing such as painting. ,
Painting can be omitted.

[Brief description of drawings]

FIG. 1 shows a sectional view of a synthetic resin molding die of the present invention.

FIG. 2 shows a cross-sectional view of a synthetic resin molding die of the present invention.

FIG. 3 shows a sectional view of a synthetic resin molding die of the present invention.

FIG. 4 is a graph showing a change (calculated value) in the temperature distribution near the mold wall surface when a heated synthetic resin comes into contact with a steel main mold.

FIG. 5 shows changes in temperature distribution (calculated values) near the mold wall surface when a heated synthetic resin comes into contact with a mold in which the mold surface of a steel main mold is coated with 0.1 mm of polyimide. It is a graph figure which shows.

FIG. 6 shows changes in temperature distribution (calculated values) near the wall surface of a mold when a synthetic resin heated to contact a mold surface of a steel main mold with 0.5 mm of polyimide. It is a graph figure which shows.

FIG. 7: Synthesis when heated synthetic resin comes into contact with a mold in which the surface of a steel main mold is coated with 0.3 mm of polyimide and the surface of which is further coated with nickel of 0.02 mm It is a graph which shows the temperature change (calculated value) of resin surface (interface of resin surface and metal mold surface).

FIG. 8: Synthesis when heated synthetic resin comes into contact with a die in which 0.3 mm of polyimide is coated on the die surface of a steel main die and 0.1 mm of nickel is further coated on the surface. It is a graph which shows the temperature change (calculated value) of resin surface (interface of resin surface and metal mold surface).

FIG. 9: Synthesis when heated synthetic resin comes into contact with a mold in which the surface of a steel main mold is coated with 0.15 mm of polyimide, and the surface of which is further coated with 0.02 mm of nickel It is a graph which shows the temperature change (calculated value) of resin surface (interface of resin surface and metal mold surface).

FIG. 10: Synthesis when heated synthetic resin comes into contact with a mold in which the surface of a steel main mold is coated with 0.15 mm of polyimide and the surface of which is further coated with 0.1 mm of nickel It is a graph which shows the temperature change (calculated value) of resin surface (interface of resin surface and metal mold surface).

FIG. 11: The surface of the main mold made of steel is coated with 0.3 mm of polyimide, and the surface is further covered with 0.0005 mm,
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 comes into contact with the mold coated with nickel of 0.02 mm and 0.1 mm in thickness It is a graph figure which shows.

FIG. 12: The surface of a steel main mold is coated with 0.15 mm of polyimide, and the surface is further covered with 0.0005 mm;
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 comes into contact with the mold coated with nickel of 0.02 mm and 0.1 mm in thickness It is a graph figure which shows.

FIG. 13 is a perspective view of injection-molded products used in Examples and Comparative Examples.

[Explanation of symbols]

 1 Main Mold 2 Heat Insulation Layer 3 First Metal Layer 4 Second Metal Layer 5 Third Metal Layer 6 Wrinkled Metal Layer Surface 7 Molded Product 8 Hole 9 Gate 10 Weld Line A Heat Insulation Layer Thickness B Metal Layer Thickness

Claims (2)

[Claims] 1. A heat-resistant polymer of 0.1 to 0.5 is formed on a mold wall surface of a mold cavity of a main mold made of metal.
There is a heat insulating layer with a thickness of mm, and the thickness of the heat insulating layer is 1
/ 5 or less, and a thickness of 1 to 50 μm, a heat insulating layer-covering mold for molding synthetic resin, in which a metal layer adhered to the heat insulating layer is present. 2. When the heated synthetic resin to be molded comes into contact with the mold surface, the mold surface temperature is 20 ° C. higher than the softening temperature of the synthetic resin.
The heat-insulating layer-covering mold for synthetic resin molding according to claim 1, wherein the heat-insulating layer and the metal layer have a thickness capable of raising the temperature to a higher temperature.