JP2706221B2 - Heat insulating layer coated mold for molding synthetic resin and molding method using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold and
And a molding method using the same . More specifically, the present invention relates to a heat-insulating-layer-coated mold used for molding such as injection molding and blow molding, which can withstand tens of thousands of moldings of a synthetic resin, and a molding method using the same.

[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. This can be achieved to some extent by selecting molding conditions such as increasing the temperature of the mold and the mold, 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 increases, and the molding efficiency decreases.
Improves the reproducibility of the mold surface without increasing the mold temperature,
There is also a demand for a method in which the required cooling time is not prolonged even when the mold temperature is increased. Heating and cooling holes are attached to the mold, and heating and cooling are repeated by alternately flowing a heat medium and a coolant.However, this method also consumes a large amount of heat. , The cooling time becomes longer.

A method of improving the mold surface reproducibility by coating the mold wall surface forming the mold cavity with a substance having a low thermal conductivity, that is, a heat insulating layer, is described in WO 93/94.
JP 06980 discloses the use of polyimide as a heat insulating layer, and JP-A-54-142266 discloses the use of an epoxy resin as a heat insulating layer.

[0005]

One of the advantages of injection molding and blow molding is that a molded article having a considerably complicated shape can be formed by a single molding. Therefore, the mold cavity shapes of these molds are generally complex. On the other hand, the thickness of the heat-insulating layer of the heat-insulating-layer-coated mold is 0.1 m in general high-speed injection molding.
m may be sufficient, but even in injection molding, depending on the molding conditions, it may be about 0.1.
A thickness of about 2 to 0.4 mm is required. Further, in the blow molding, a heat insulating layer having a thickness of 0.3 mm or more, and sometimes 0.4 mm or more is required. There is a demand for economically covering a thick heat insulation layer on a complicated mold wall surface.

[0006] As a method for uniformly covering a thick heat insulating layer on the wall surface of a mold cavity having a complicated shape, a method of applying a paint to a thin film by a spray coating method, a brush coating method, or the like has been used several times, and in some cases, several times. It has been repeated ten times to obtain a thick coating film. If paint is applied to a thick wall at a time on a mold wall with a complicated shape, the paint will sag during application,
It was difficult to apply evenly on a complicated mold wall.
The dripping amount (Q) of the paint is generally represented by the following formula, and is said to be proportional to the cube of the thickness (t) of the paint before curing immediately after application. Q = dgt ³ / η (where Q is the amount of paint dripping, d is the specific gravity of the paint, g is the acceleration of gravity, η is the viscosity of the paint, and t is the thickness of the paint.) In order to reduce (Q) and apply the coating uniformly, it is necessary to reduce the thickness (t) of the coating by reducing the amount applied at one time. In other words, it was necessary to repeat the [coating of the coating on the thin film → drying, solidification by crosslinking, etc.] many times, and sometimes several tens of times, to increase the thickness. In order to form a coating film as thick as possible at a time without causing dripping of the coating material, it is preferable that the solvent be reduced to increase the concentration of the coating material and that spray coating or brush coating can be performed at a high concentration. However, a high concentration generally results in a high viscosity, making the coating process difficult. A paint having a high concentration and a low viscosity is preferable, and from this viewpoint, a paint having a low molecular weight at the paint stage and reacting after application to become a high molecular weight is preferable.

[0007] A thermosetting resin whose molecular weight is increased by a cross-linking reaction of an epoxy resin or the like is an extremely preferable paint from the viewpoint of thick film coating. However, when these thermosetting resins are highly crosslinked, their elongation generally becomes small and brittle, and when coated on a metal mold wall,
There was a problem that cracks and the like occurred during use of the mold. Furthermore, the heat insulating layer covering the mold surface also needs heat resistance, and when epoxy resin or the like is used as the heat insulating layer, it is necessary to improve the contradictory properties of heat resistance and toughness.
In order to strengthen the epoxy resin, various liquid rubbers and the like have been added for a long time. However, even if a rubber is added to a heat-resistant epoxy resin having a high crosslinking density, the effect of the rubber is generally difficult to appear.

On the other hand, it is preferable that the heat-insulating layer coated on the surface of the metal mold can be peeled off if necessary. When the heat insulating layer is damaged, it is preferable that the heat insulating layer can be peeled off once and the heat insulating layer can be covered again. That is, it is preferable that the film does not peel off during molding but can be peeled off when it is desired to peel off.

Further, the heat insulating layer coated on the surface of the mold is preferably formed into a mirror-like surface by polishing, and it is preferable that the heat insulating layer has good polishing properties, that is, a heat insulating layer which becomes a mirror surface by polishing. What is required of the heat insulation layer is
It has good thick coating properties, excellent heat resistance and elongation, and excellent durability during molding. It does not peel off at the time of molding, but it can be peeled off when necessary and has an abrasiveness that can be mirror-polished.

[0010]

Means for Solving the Problems 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, its coating state, The present inventors have studied the combination with the mold material and the like, and have reached the present invention. That is, the present invention relates to a method in which the mold wall of the main mold made of metal has a thickness of 0.01 to 2 m.
m is a mold coated with a heat-insulating layer having a thickness of m, and the heat-insulating layer is composed of at least two layers of a layer made of a heat-resistant polymer having a linear high molecular weight and a layer made of a cross-linked high molecular weight polymer. the thickness of the layer composed of the high molecular weight polymer Ri thermal barrier coating die der for synthetic resin molding, which accounts for more than half of the thickness of the entire heat insulating layer,
Further, it is a molding method using the mold.

Hereinafter, the present invention will be described in detail. The linear high molecular weight heat-resistant polymer in the present invention is preferably an amorphous heat-resistant polymer having an aromatic ring in the main chain. The crosslinked high molecular weight polymer in the present invention is preferably an epoxy resin, a polyurethane resin, a polycyanurate resin, a thermosetting polyimide resin, or the like.

The heat-insulating layer-coated mold of the present invention has a layer made of a linear high molecular weight polymer near the interface between the heat-insulating layer and the metal mold and / or near the heat-insulating layer surface. It is preferable to use a heat insulating layer having a crosslinked high molecular weight polymer layer. The synthetic resin molded using the mold of the present invention is a thermoplastic resin that can be used for general injection molding and blow molding, and is a polyolefin such as polyethylene and polypropylene, polystyrene, styrene-acrylonitrile copolymer, and rubber-reinforced polystyrene. Styrene resin such as ABS resin, polyamide, polyester, polycarbonate, methacrylic resin, vinyl chloride resin and the like. These synthetic resins can contain 1 to 60% of a resin reinforcement. Various types of rubber, glass fiber,
Various fibers such as carbon fiber, talc, calcium carbonate,
Inorganic powder such as kaolin.

The main mold comprising the mold described in the present invention is:
It includes metal molds generally used for molding synthetic resins, such as iron or iron-based steel, aluminum or aluminum-based alloys, zinc alloys, and beryllium-copper alloys. 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 crosslinked high molecular weight polymer used in the present invention is a highly crosslinked high molecular weight polymer. It is a polymer that is applied with a low molecular weight paint and reacts by heating or the like to cause crosslinking to form a high molecular weight polymer, preferably having a glass transition temperature of 100 ° C. or higher, more preferably 15 ° C. or higher.
It is a heat-resistant thermosetting resin of 0 ° C. or higher. The cross-linked high molecular weight polymer used well is selected from epoxy resins, thermosetting polyimide resins, polycyanurate resins, polyurethane resins and the like.

The epoxy resin used in the present invention has an average of two or more epoxy group bonds per molecule. These compounds are saturated or unsaturated aliphatic, aromatic or heterocyclic compounds, which may have a substituent such as halogen, hydroxy, ether and the like. Particularly preferred epoxy compounds include (1) glycidyl ether of polyphenol, (2) glycidyl ether of polyphenyl ether, (3) aromatic glycidyl compound,
(4) Polynuclear aromatic glycidyl ether and (5) glycidyl ether glycidylbenzene.

(1) The glycidyl ether of polyphenol is obtained by reacting epichlorohydrin with polyphenol in the presence of an alkali. Preferred glycidyl ethers of polyphenols include, for example, 2,2-bis (4-hydroxyphenyl) propane, 1,1 ', 2,2
2'-tetrakis (4-hydroxyphenyl) ethane,
α, α, α ′, α ′, α ″, α ″ -hexakis (4-hydroxyphenyl) -1,3,5-triethylbenzene 1,3,5-trihydroxybenzene or 1,1,5
Examples include 5-tetrakis (hydroxyphenyl) pentane and other glycidyl ethers of novolak obtained by reacting novolak obtained by reaction of polyhydroxyphenol with formalin and epichlorohydrin.

(2) Preferred examples of the glycidyl ether of polyphenyl ether include glycidyl ether of dihydroxydiphenyl ether. The epoxy resin prepolymer synthesized from bisphenol A and epichlorohydrin has the following structural formula.

[0018]

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(Wherein n is in the range of 0 to 20). Further, bisphenol A and tetrabromobisphenol A
A typical epoxy resin synthesized from and epichlorohydrin has the following structural formula.

[0020]

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In the above equation, when the number of n is relatively increased with respect to m, the flame retardancy increases. (3) Preferred examples of the aromatic glycidyl compound include 1,
There is 3,5-tri (epoxyethyl) benzene. (4) The polynuclear aromatic glycidyl ether is glycidyl ether of naphthalene diol or glycidyl ether of novolak and has the following structure.

[0022]

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(5) The glycidyl ether-glycidylbenzene preferably has the following structure.

[0024]

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The epoxy resin described herein is cured by adding a curing agent. The curing agent reacts with the epoxy resin to form a three-dimensional network. The curing agent is classified into a latent type and a latent type according to the mechanism of action, and a polyaddition type and a catalyst type according to the reaction mechanism. Each type has a large number of types, and is selected and used as needed. Examples of the manifestation type and the polyaddition type include diethylenetriamine, triethylenetetramine,
Tetraethylenepentamine, diethylaminopropylamine, mensendiamine, isophoronediamine, N-aminoethylpiperazine, 3,3-bis (3-aminopropyl) -2,4,8,10-tetraoxyspiro (5,
5) Undecane adduct, bis (4-amino-3-methylcyclohexyl) methane, bis (4-aminocyclohexyl) methane, m-xylenediamine, diaminodiphenylmethane, m-phenylenediamine, diaminodiphenylsulfone, phthalic anhydride, tetrahydroanhydride Phthalic acid, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic anhydride, dodecylsuccinic anhydride, chlorendic anhydride, pyromellitic anhydride, benzophenonetetracarboxylic anhydride, ethylene Glycol bis (anhydrotrimate), methylcyclohexenetetracarboxylic anhydride, trimellitic anhydride, polyazeleic anhydride, polymercaptan, polysulfide and the like. Examples of the manifest type and the catalytic type are 2, 4, 6
-Tris (dimethylaminomethyl) phenol, 2-ethyl-4-methylimidazole, BF ₃ monoethylamine complex and the like.

As the epoxy resin, it is particularly preferable to use a cured epoxy resin having high heat resistance and high elongation at break. In general, to improve the heat resistance of the epoxy resin, there are methods such as increasing the crosslink density, introducing a heat resistant skeleton, and blending another heat resistant resin. An epoxy resin cured product obtained by curing an epoxy resin represented by the following chemical formulas (5) and (6) with a curing agent represented by the following chemical formulas (7) and (8) has a glass transition temperature exceeding 200 ° C. and a relatively large elongation at break. It can be used particularly well.

[0027]

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[0028]

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[0029]

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[0030]

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As the epoxy resin, a cured epoxy resin having improved impact resistance can be used particularly well. There are various means to improve the impact resistance of epoxy resin, but various rubber compounds such as nitrile rubber, heat-resistant and impact-resistant resin compounds such as polyetherimide, polysulfone, polyethersulfone, nylon, etc. Can be used well. Nitrile rubber, polyethersulfone, polyetherimide, polysulfone, and the like have good compatibility with the epoxy resin, and the cured epoxy resin containing these compounds has good impact resistance and can be used favorably in the present invention. These polyetherimides,
Epoxy resin cured product containing polyether sulfone, etc.
Is a crosslinked high molecular weight polymer described in the present invention.
Layer.

Examples of the thermosetting polyimide used as the crosslinked high molecular weight polymer include various bismaleimide resins having the chemical compositions shown in Table 1 and siloxane-containing bismaleimide resins using the substances shown in the following chemical formulas 9 to 10. And nadic acid-terminated polyimide resin, acetylene-terminated polyimide resin, and the like.

[0033]

[Table 1]

[0034]

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[0035]

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In general, thermosetting polyimide resins have low elongation and are brittle. Various studies have been made on polymer alloys with other resins to increase the toughness, but these can be used favorably. For example, a polymer alloy of a thermosetting polyimide resin and a linear high molecular weight polyimide resin can be used favorably. These can be obtained by blending a precursor solution of a linear high molecular weight polyimide with a monomer of a thermosetting polyimide resin.

As the polyurethane resin used as the crosslinked high molecular weight polymer, a two-component polyurethane paint, a baking polyurethane paint, a moisture-curable polyurethane paint and the like can be used. A polycyanurate resin having a triazine ring formed by reacting a monomer having two or more aromatic cyanate groups as shown in the following formula 11 has high heat resistance and large elongation at break, and is preferably used in the present invention. it can.

[0038]

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Each of the crosslinked high molecular weight polymers can be used by blending with each other. For example, an epoxy resin, a urethane resin, a polycyanurate resin, or the like can be used by blending with each other. In the crosslinked high molecular weight polymer such as epoxy resin, it is possible to satisfactorily mix inorganic powder such as talc, calcium carbonate, and clay, and various fillers such as fiber such as glass fiber, carbon fiber, and whisker. . By blending these fillers, the thermal expansion coefficient of the heat insulating layer can be reduced.

The crosslinked high molecular weight polymer of the present invention preferably has a breaking elongation of 1% or more, more preferably 1.
It is at least 5%, most preferably at least 2%. The greater the elongation at break, the greater the durability against thermal shocks when the mold is used. However, in the present invention, a crosslinked high molecular weight polymer having a relatively small elongation at break can be used by using a linear high molecular weight polymer layer having a large elongation at break and an appropriate multilayer structure.

The linear high molecular weight heat-resistant polymer of the present invention has a glass transition temperature of 150 ° C. or higher, preferably 180 ° C.
℃ or more, or melting point is 200 ℃ or more, preferably 25
It is a linear high molecular weight polymer at 0 ° C. or higher, and a tough polymer having a breaking elongation of 10% or more, preferably 15% or more. Particularly useful in the present invention is a heat-resistant amorphous resin, polyimide, polyetherimide,
Polysulfone, polyethersulfone and the like can be particularly preferably used. An amorphous resin having a large elongation at break and excellent heat resistance is excellent in impact resistance. The elongation at break described in the present invention is measured according to ASTM D638. The pulling speed at the time of measurement is 5 mm / min.

Polyimide has excellent heat resistance and can be used particularly favorably. Polyimides having the repeating units shown in Table 2 can be used favorably.

[0043]

[Table 2]

In order to coat the complex mold surface with polyimide and to make the polyimide adhere firmly, it is most preferable to apply a polyimide precursor solution and then heat to form the polyimide. The linear polyimide precursor is synthesized, for example, by subjecting an aromatic diamine and an aromatic tetracarboxylic dianhydride to a ring-opening polyaddition reaction as shown in the following Chemical Formula 12.

[0045]

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These polyimide precursors are heated to cause a dehydration cyclization reaction to form a polyimide. The most preferred straight-chain polyimide precursor in the present invention is polyamic acid, and a typical example of the repeating unit and a polyimide repeating unit obtained by imidizing the same are shown in the following formulas (13), (14), (15) and (16).

[0047]

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[0048]

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[0049]

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[0050]

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The polymer of the above polyimide precursor is N-
It is dissolved in a solvent such as methylpyrrolidone and applied to the mold wall. To the polyimide precursor solution, to adjust the viscosity at the time of coating, to adjust the surface tension of the solution, to add an additive to adjust the thixotropic property, and / or to increase the adhesion with the mold Minor additives can be added.

Since the polymer of the polyimide precursor contains a carboxyl group and the like, it has good adhesion to the mold, and a polyimide thin layer adhered to the mold surface can be obtained by reacting and forming polyimide on the mold surface. Polyetherimides that can be used favorably are those described in JP-A-60-127360 or JP-A-60-156755. That is,
7 is a polymer.

[0053]

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(In the formula, a represents an integer larger than 1, for example, 10 to 10,000 or a larger integer. Z is selected from the group consisting of divalent organic groups represented by the following formulas 18 to 24. The divalent linkage of the —O—Z—O— group is on the phthalic anhydride terminal group, eg, 3,
It is in the 3 ', 3,4', 4,3 'or 4,4' position. R is an aromatic hydrocarbon group having 6 to about 20 carbon atoms and a halogenated derivative thereof; an alkylene group and a cycloalkylene group having about 2 to about 20 carbon atoms; a C2 to C8 alkylene-terminated polydiorganosiloxane; It is a divalent organic group represented by Chemical Formulas 25 and 26. )

[0055]

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[0056]

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[0057]

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[0058]

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[0059]

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[0060]

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[0061]

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[0062]

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[0063] (wherein, X is -C _y H _2y - _(y is an integer of from 1 to 5), - O -, - S -, - CO-, and -SO ₂ -
Is selected from the group consisting of divalent groups, and q is 0 or 1. )

[0064]

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(Wherein Q is —O—, —CO—, —SO ₂
And -C _x H _2x- (X is an integer of 1 to 5) and is one selected from the group consisting of divalent groups. The most preferred polyetherimide is a polymer having a unit represented by the following formula 27 as a monomer ("Ultem 1000" manufactured by General Electric Co., Ltd.).

[0066]

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The polysulfone which can be favorably used in the present invention is an aromatic polysulfone having excellent heat resistance and impact resistance mainly composed of a repeating unit having the following structure.

[0068]

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The polyethersulfone which can be favorably used in the present invention is an aromatic polyethersulfone having excellent heat resistance and impact resistance mainly composed of repeating units having the following structure.

[0070]

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Polyetherimide, polyether sulfone, and polysulfone have good compatibility with epoxy resins, and can be used as a polymer alloy to improve the impact resistance of epoxy resins. The total thickness of the heat insulating layer is appropriately selected in the range of 0.01 to 2 mm. Preferably, 0.1 to 0.01 to 0.3 mm, more preferably in an injection molding
0.3 mm, 0.3 to 1.0 m for blow molding
m, more preferably from 0.35～0.6Mm.

In the present invention, the heat insulating layer comprises at least two layers of a layer composed of a linear high molecular weight heat-resistant polymer and a layer composed of a crosslinked high molecular weight polymer, and is composed of a crosslinked high molecular weight polymer. The thickness of the layer occupies half or more, preferably 55 to 99%, more preferably 60 to 95% of the thickness of the entire heat insulating layer, and makes use of the thick coating property of the thermosetting resin. The heat insulating layer may be composed of two layers, or may be composed of three layers. In the case where the heat insulating layer is two layers, a layer made of a polymer having an appropriate adhesive force with the mold is provided at the interface in contact with the metal mold at the interface in contact with the metal mold. A layer comprising a crosslinked high molecular weight polymer is provided thereon. By providing a thin layer of a polymer with excellent heat resistance and impact resistance such as linear high molecular weight polyimide at the interface directly in contact with the metal mold, durability during molding is improved, and Adhesive force to a mold can be made moderate, and peeling at the time of molding can be eliminated, while peelability when peeling is desired can be improved.

When the heat insulating layer is composed of three layers, a layer composed of a linear high molecular weight polymer having excellent heat resistance and impact resistance is further provided on the surface of the two heat insulating layers. And By providing a layer of a linear high molecular weight polyimide or the like on the outermost surface, durability and the like can be further improved. When the surface of the metal mold is coated with a heat insulating layer having a coefficient of thermal expansion that is significantly different from the coefficient of thermal expansion of the metal mold, repeated thermal shock is greatest at the interface during molding using the mold. This is likely to cause peeling or cracking of the heat insulating layer. When a heat insulating layer having a thermal expansion coefficient close to that of a metal mold is coated, the generated thermal shock is reduced. It is very preferable from this viewpoint to coat a linear high molecular weight polyimide having a coefficient of thermal expansion extremely close to that of a metal mold.

In the present invention, a linear high molecular weight polymer layer having a large breaking elongation is provided near the interface between the heat insulating layer and the metal mold where stress is most likely to be applied and near the heat insulating layer surface. The object of the present invention is attained by forming a crosslinked high molecular weight polymer layer which can be easily applied to meat. In the present invention, the outermost surface of the heat insulating layer can be further coated with a thinner metal layer by plating or the like. The metal of the outermost surface layer used here is a metal generally used for metal plating and the like, and is one kind of chromium, nickel, copper, zinc, iron, aluminum, titanium, tin-cobalt alloy, iron-nickel alloy and the like. Or two or more. The metal layer is coated on the surface of the heat insulating layer, and its thickness is 1/5 or less, preferably 1/8 or less, 1/200 or more, more preferably 1/10 or less, of the total heat insulating layer. / 100 or more. If the metal layer is too thick, the effect of coating the main mold surface with the heat insulating layer is reduced. On the other hand, if the metal layer is too thin, it is not possible to achieve the purpose of attaching the metal layer, such as prevention of damage. However, with respect to the improvement of the releasability at the time of molding, the effect is exhibited even if the metal layer is considerably thin. Generally, 1/10 or less of the thickness of the heat insulating layer, 1/100
The above is particularly preferred.

The adhesive strength between the heat insulating layer of the present invention and the main mold needs to be appropriate, and is 0.5 to 6 kg / 10 at room temperature.
mm width, preferably 0.8 to 5 kg / 10 mm width, more preferably 1 to 4 kg / 10 mm width. This is done by cutting the closely adhered heat-insulating layer to a width of 10 mm, and
It is the peeling force when pulled at a speed of 0 mm / min. Although this peeling force varies considerably depending on the measurement location and the number of measurements, the minimum value and the maximum value are important, and a stable peeling force is preferable. 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. However, it is not preferable that the heat-insulating layer is cut off at the time of peeling because the adhesion is too strong.

The heat insulating layer may be coated on the entire surface of the mold wall forming the mold cavity of the main mold made of metal,
A part of the mold wall surface may be covered. For example, when covering the mold wall surface forming the front side of the molded product, covering the mold wall surface forming the portion requiring slidability on the molded product, covering the mold wall surface forming the back surface side of the molded product if you did this,
There are cases where the mold wall surface forming the end face of the molded product is covered, and where the corners of the mold wall surface forming the ribs and bosses on the back side of the molded product are covered.

The method of applying the heat insulating material of the present invention is carried out by a method such as brushing or spraying an uncured paint or a paint solution. The viscosity at the time of application is adjusted by adding a solvent, adjusting the temperature, or the like.

[0078]

EXAMPLE The following main mold and heat insulating layer are used. Main mold: A blow mold for the air spoiler in the tail of a passenger car, made of zinc alloy (ZAS). The mold surface is hard chrome plated. The thermal expansion coefficient of the main mold is 2.8 × 10 ^-5 / ° C. Modified epoxy resin: rubber-modified epoxy resin (Cemedine EP-007, trade name, manufactured by Cemedine Co., Ltd.). The elongation at break after curing is 6%, and the thermal conductivity is 0.0005 cal / cm.
.Sec..degree. C., coefficient of thermal expansion is 7.times.10@-5 /.degree. Epoxy resin: Diglycidyl ether of bisphenol A (AER331, trade name, manufactured by Asahi Chiba Corporation). Curing agent: diaminodiphenylmethane. Polyether sulfone: Victorex PES (trade name, manufactured by ICI). The glass transition temperature is 225 ° C. and the elongation at break is 50%. Polyimide: Linear high molecular weight polyimide precursor solution (L
ark TPI manufactured by Mitsui Toatsu Chemical Industry Co., Ltd.). The glass transition temperature of the cured polyimide is 256 ° C., the elongation at break is 25%, and the thermal conductivity is 0.0005 cal / cm · sec.
° C., thermal expansion coefficient is 3.5 × 10 -5 / ° C.

[0079]

Embodiment 1 A polyimide was applied to the wall surface of the main mold, and 290
The composition is cured by heating to a temperature of 0 ° C. to form a 0.02 mm thick polyimide layer. Next, a modified epoxy resin was applied on top of it.
A 4 mm thick heat insulating layer is formed. Next, the surface is further coated with a polyimide layer having a thickness of 0.02 mm in the same manner. Next, the heat-insulating layer is polished to a mirror-like surface to produce the heat-insulating-layer-coated mold of the present invention. The surface of the heat insulating layer is mirror-like, and the peel strength of the heat insulating layer is 1.5 kg / 10 mm width. Tough and excellent heat resistance at the interface between the main mold and the modified epoxy resin layer,
In addition, by providing a polyimide thin film having a coefficient of thermal expansion very similar to the coefficient of thermal expansion of the main mold, the durability of the mold at the time of molding is improved, and the heat-insulating layer coated mold suitable for synthetic resin blow molding. Is obtained.

[0080]

Example 2 The following epoxy resin is used in place of the modified epoxy resin of Example 1. After uniformly mixing epoxy resin / polyether sulfone / curing agent = 100/63/26 (weight ratio) and adjusting the viscosity with a solvent, 0.1 wt.
Apply evenly to a thickness of 4 mm. Raise the temperature and finally 200 ℃
For 30 minutes to evaporate the solvent and cure the epoxy resin, thereby forming a heat insulating layer made of a polymer alloy of the epoxy resin. The polymer alloy of the epoxy resin has a glass transition temperature of 170 ° C., an elongation at break of 5%, heat resistance, toughness,
Excellent hardness. 3 with polyimide in the same manner as in Example 1.
With the layer structure, the excellent heat insulating layer-coated mold of the present invention is obtained.

[0081]

The present invention provides a heat-insulating layer-coated mold excellent in thick coating property, molding durability, surface polishing property, etc., and performing injection molding or blow molding of a synthetic resin using the mold. Obtain molded products with good appearance.

Claims (2)

(57) [Claims] 1. A mold in which a mold wall constituting a mold cavity of a main mold made of metal is coated with a heat insulating layer having a thickness of 0.01 to 2 mm, and the heat insulating layer has a linear high molecular weight heat resistance. A layer composed of a polymer and a layer composed of at least two layers composed of a crosslinked high molecular weight polymer, and the thickness of the layer composed of the crosslinked high molecular weight polymer occupies at least half of the thickness of the entire heat insulating layer. Heat insulation layer coating mold. 2. Synthesis using the heat-insulating layer-coated mold according to claim 1.
Resin molding method.