JP2000084943A - Insulating mold and molding method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an insulating mold which can achieve a good appearance even in a complex three-dimensional shape and be manufactured in a short time. SOLUTION: In an insulating mold to be used in a molding method in which an insulating layer is incorporated into the main mold in a mold to be used in the molding of a thermoplastic resin composition, the main mold is kept at a temperature lower than the Tg of the resin composition, and the highest temperature of the mold cavity surface temperature of a part incorporated with the insulating layer during molding is (Tg+1)-(Tg+50 deg.C), the thickness of the insulating layer in a mold cavity part to be incorporated with the insulating layer is 0.01-2 times the wall thickness of a molding, and the insulating layer is made of the synthetic resin composition 1.0 W/m.K or below in thermal conductivity and molded by a three-dimensional molding method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-insulating mold capable of achieving a high appearance even in a complicated three-dimensional shape, and a molding method using the same. More specifically, a complex 3D composition can be used without impairing the excellent properties of the thermoplastic resin composition to be molded.
The present invention relates to a heat-insulating mold capable of achieving a high appearance even in a three-dimensional shape and capable of being produced in an extremely short time, and a molding method using the same.

[0002]

2. Description of the Related Art When molding a thermoplastic resin by an injection molding method or a blow molding method, the mold surface transferability of a mold is improved, the gloss of a molded product is excellent, and a weld line, a flow mark, a jet mark, and the like are obtained. There is always a demand for a high-quality appearance with reduced appearance defects such as filming. Conventionally, post-processing such as painting is generally performed to improve these appearance defects, but in recent years, painting has been carried out for recycling after use of molded products, environmental problems at the time of painting, and cost reduction. There is a great demand for less

In order to improve the mold surface transferability of a mold during molding, obtain a molded article having excellent gloss and excellent appearance with reduced appearance defects such as weld lines, flow marks and jetting. In general, the molding conditions such as high mold temperature and resin temperature, high injection pressure, high-speed injection and the like are optimized, thereby achieving the object to some extent.

[0004] Among these molding conditions, the one having the greatest influence is the mold temperature, and it is particularly preferable to increase the mold temperature in order to obtain a molded article having a high appearance. But,
Increasing the temperature of the entire mold increases the cooling time required for cooling the molten thermoplastic resin in the mold to a temperature at which the molded product can be taken out, thereby lowering production efficiency.
Therefore, there is a demand for a method of obtaining a molded article having a high appearance without increasing the temperature of the entire mold, and a molding method which does not lower the production efficiency even if the mold temperature is increased.

In response to these demands in recent years, for example, a method of heating and cooling by providing a cooling pipe for heating and cooling in a mold and alternately circulating a heat medium and a cooling medium in accordance with a molding process. Has been done. However, this method consumes high heat energy and does not improve production efficiency. On the other hand, a method of improving the transferability of the mold surface by providing a heat insulating layer with a material having a low thermal conductivity on the mold wall surface to locally heat only the mold surface during molding and improving the mold transferability has been proposed for a long time. For example, US Pat. No. 3,544,518 and WO 89/10
No. 823 is disclosed. However, USP 354
The heat insulating layer of No. 4518 is specifically a polyethylene terephthalate film, and has a drawback that it cannot sufficiently cope with a case where the molded article has a complicated three-dimensional shape. WO8
Similarly, Japanese Patent Application No. 9/10823 uses a polyimide plate as a heat insulating layer, and has a drawback that it is difficult to cope with a complicated mold surface shape. To solve this problem, Japanese Patent Application Laid-Open No. 7-80187 discloses a method of forming a polyimide heat insulating layer by repeatedly applying a linear polyimide precursor solution to a mold wall surface and heating the mold. Although this method can be applied to a mold wall having a three-dimensional shape, it is necessary to apply a linear polyimide precursor solution to the mold wall and repeat heating several times. There were disadvantages. Further, when the shape of the mold is complicated, it is necessary to adjust the dimensions by machining or the like, but in the case of a mold having a complicated three-dimensional shape, there is a drawback that it is not possible to cope with the problem. Was.

[0006]

SUMMARY OF THE INVENTION The present invention can achieve a high appearance even in a complicated three-dimensional shape without impairing the excellent properties of the thermoplastic resin composition to be molded, and can be produced in a very short time. It is an object of the present invention to provide a possible heat-insulating mold and a molding method using the same. We have:
As a result of intensive studies to achieve the above object, in a heat-insulating mold in which a heat-insulating layer is incorporated at an arbitrary position on the mold surface of a metal main mold, such a heat-insulating layer is produced by a three-dimensional molding method, and It has been found that the above object can be achieved by setting the thickness of the heat insulating layer to a specific range with respect to the thickness of the molded product at the corresponding portion, and the present inventors have further studied and completed the present invention.

[0007]

SUMMARY OF THE INVENTION According to the present invention, a heat insulating layer is incorporated in a main mold of a mold used for molding a thermoplastic resin composition, and the main mold has a Tg of the thermoplastic resin composition. Is maintained at a low temperature, and the maximum temperature at the time of molding of the mold cavity surface temperature of the portion where the heat insulating layer is incorporated is Tg +
A heat-insulating mold used in a molding method in the range of 1 to Tg + 50 ° C., wherein the thickness of the heat-insulating layer in a mold cavity portion incorporating the heat-insulating layer is 0.01 to 2 times the thickness of the molded product. A heat insulating layer comprising a synthetic resin composition having a thermal conductivity of 1.0 W / m · K or less, wherein the heat insulating layer is formed by a three-dimensional forming method. It is.

The three-dimensional molding method used in the present invention is generally called an additive manufacturing method, and is well known as a method of manufacturing a prototype by rapid prototyping or a mold for rapid tooling at a low cost in a short period of time. Things.

As the three-dimensional molding method used here, there are an optical molding method, a powder sintering method, an ink-jet method, a resin extrusion method, a sheet cutting method, etc., which can easily form a heat insulating layer having a complicated three-dimensional shape. . As a preferable three-dimensional shaping method for using the obtained modeled object as a heat insulating layer, a heat insulating layer having a complicated three-dimensional shape is formed in a short time, and the material constituting the modeled object has high heat resistance, and Since low thermal conductivity is required, stereolithography is particularly preferred.

A basic modeling process of the three-dimensional molding method will be briefly described. In general, examples of the material for lamination molding used in the three-dimensional molding method include resin, paper, metal powder, and the like. In particular, a photocurable resin is materially modified on the assumption that it is used as a mold for injection molding. Quality is added. In the three-dimensional printing method, the shape data of a formed object is created using three-dimensional CAD, converted into a format usable in the three-dimensional printing method, and then the cross-sectional shape divided into an arbitrary layer thickness is optically formed. A three-dimensional structure can be obtained by laminating by a method, a powder sintering method, an inkjet method, a resin extrusion method, a sheet cutting method, or the like.

In the present invention, the main mold refers to the entire structure of the mold, and is the one into which the heat insulating layer is incorporated.
The main mold is made of a metal and therefore of a material having good thermal conductivity. The effect of the present invention can be achieved by the fact that the metal constituting the main mold has basically good thermal conductivity, while the thermal conductivity of the heat insulating layer at a specific portion is low. Since the heat-insulating layer of the present invention is formed by a three-dimensional forming method, any three-dimensional shape requiring an arbitrarily selected high appearance of the metal surface of the main die made of metal can have any complicated three-dimensional shape. Even if it has, it can be manufactured at a low cost in a short time.

The stereolithography method according to the present invention is intended for any conventionally known stereolithography method.
A free liquid level method in which light is irradiated from above the liquid surface of the photocurable resin, the resin is cured at the liquid surface, and the table is lowered at a specific pitch for lamination, and photocuring in a transparent container Any of the regulated liquid level methods in which the conductive resin is irradiated with light from the lower side of the container to perform lamination can be used. Further, in such an optical molding, it is also possible to directly mold the optical molded article on the main mold of the mold, or to directly mold the optical molded article on the nest of the main mold and incorporate the nested portion into the main mold. ,
In addition, any method of a structure in which a molding die usually formed by stereolithography is incorporated in a main mold can be used.

Further, the present invention uses visible light, ultraviolet light, infrared light, near-infrared light and especially those laser lights as light for inducing curing used in stereolithography, and cures in response to such light. The main object is a molding system composed of a photo-curable resin, and an electron beam, an X-ray, and an energy beam such as a high-energy particle beam. Can also be used effectively. Also, a molding method for accurately positioning and projecting a reaction unit of the chemical substance on a substance which reacts and cures with the chemical substance, and a so-called lithography method of projecting the light, energy rays and the chemical substance through a mask. It can also be used effectively in a modeling system using. The most preferably used ones are
Ultraviolet laser light is used from the viewpoints of the production period, the device, the handling of the light source, and the like. However, in some cases, stereolithography using infrared light or near-infrared light, which enables more precise lamination, is also useful.

The heat insulating layer of the present invention has such a thermal conductivity of 1.
There is no particular limitation as long as the synthetic resin composition is 0 W / m · K or less. As a specific example of such a material for lamination molding, a photocurable resin having a thermal conductivity of 1.0 W / m · K or less obtained by molding a synthetic resin by stereolithography can be preferably exemplified. The photocurable resin may be any of a polymerizable vinyl compound and an epoxy compound, and any monomer or oligomer of a monofunctional compound and a polyfunctional compound is used. These monofunctional compounds and polyfunctional compounds are not particularly limited, and typical examples of the photocurable resin are given below.

As typical examples of the polymerizable vinyl compound, monofunctional compounds include isobornyl acrylate, isobornyl methacrylate, zinclopentenyl acrylate, bornyl acrylate, bornyl methacrylate, and 2-hydroxyethyl acrylate. , 2-hydroxypropyl acrylate, propylene glycol acrylate, vinyl pyrrolidone, acrylamide, vinyl acetate, styrene and the like.

Examples of the polyfunctional compound include trimethylolpropane triacrylate, EO-modified trimethylolpropane triacrylate, ethylene glycol diacrylate, tetraethylene glycol diacrylate,
1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, dicyclopentenyl diacrylate,
Examples include polyester diacrylate and diallyl phthalate.

One or more of such monofunctional compounds and / or polyfunctional compounds can be used alone or in the form of a mixture.

As the polymerization initiator of the vinyl compound used in the photocurable resin, a photopolymerization initiator and a thermal polymerization initiator are used, and as the photopolymerization initiator, 2,2-
Dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexylphenyl ketone, acetophenone,
Benzophenone, xanthone, fluorenone, bezaldehyde, fluorene, anthraquinone, triphenylamine, carbazole, 3-methylacetophenone, Michler's ketone, and the like can be given as typical examples, but are not limited thereto. Initiators can be used alone or in combination of two or more. If necessary, a sensitizer such as an amine compound can be used in combination.

Typical thermal polymerization initiators include benzoyl peroxide, t-butylperoxybenzoate, dicumyl peroxide, diisopropylperoxydicarbonate, t-butyl peroxide, azobisisobutyronitrile and the like. Can be mentioned. The amount of the polymerization initiator or the thermal polymerization initiator used in the present invention is preferably 0.1 to 0.1 based on the vinyl compound.
1 to 10% by weight.

Typical examples of epoxy compounds include:
Hydrogenated bisphenol A diglycidyl ether, 3,
4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, 2- (3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy) cyclohexane-m-dioxane, bis (3,4-
(Epoxycyclohexylmethyl) adipate and the like. When these epoxy compounds are used, an energy-active cation initiator such as triphenylsulfonium hexafluoroantimonide is used.

If necessary, a leveling agent, a surfactant, an organic polymer compound, an organic plasticizer, an organic filler, an inorganic filler, and the like may be added to the photocurable resin. Here, as the organic filler, other than the particulate filler of crosslinked polystyrene particles, crosslinked polymethyl methacrylate particles, crosslinked silicone particles, and wholly aromatic polyamide particles, wholly aromatic polyester fibers and wholly aromatic polyamide fibers, etc. Fibrous fillers can be mentioned.

As the inorganic filler, glass beads,
Alumina particles, talc particles, glass flakes, mica,
Examples include graphite, silica particles, wollastonite, and various whiskers. Such organic fillers and inorganic fillers have an average particle size of 0.3 to 50 μm,
Preferably, the average particle diameter is 1 to 30 μm. When the average particle size is within such a range, the viscosity of the solution before the curing treatment can be kept at an appropriate level, and at the same time, the precision of the molded article can be sufficiently maintained. From such a viewpoint, in the case of fibrous fillers such as wollastonite, whiskers and wholly aromatic polyester fibers, the above average particle size indicates the range of the fiber length.

The whiskers used in the present invention include, for example, aluminum borate whiskers, potassium titanate whiskers, magnesium hydroxide sulfate whiskers, titanium oxide whiskers, and zinc oxide whiskers. The fiber diameter of whiskers is 0.3-1μ
m is preferably satisfied, more preferably,
It is in the range of 0.3 to 0.7 μm.

In the case of a plate-like filler such as mica, talc, glass flake, etc., it is preferable that the thickness is small. For example, in the case of glass flake, particularly preferable is:
Those having an average thickness of 2 μm or less prepared by a sol-gel method or the like are used.

The amount of the organic filler and the inorganic filler is 5 to 70% by volume, more preferably 20 to 65% by volume, and particularly preferably 30 to 70% by volume in the photocurable resin composition.
This is the case of 60% by volume.

As the photocurable resin, the above-mentioned vinyl compounds and epoxy compounds may be used alone or in combination with each other. Further, if necessary, other components may be blended. The method of mixing the components is not particularly limited.

The photocurable resin has extremely high rigidity when cured, has a high surface hardness, and has excellent heat resistance, and is particularly preferable as a heat insulating layer in an injection molding method or a blow molding method.

In the present invention, the thermal conductivity of the synthetic resin used as the heat insulating layer needs to be 1.0 W / m · K or less. If the value is greater than 1.0 W / m · K, the heat insulating effect of the heat insulating layer is low, and it is difficult to suppress rapid cooling and solidification on the mold surface. More preferably, 0.
05 to 0.7 W / m · K, particularly preferably 0.1
０．６0.6 W / m · K.

In the present invention, the thickness of the heat-insulating layer must be in the range of 0.01 to 2 times the thickness of the molded product in the mold cavity where the heat-insulating layer is incorporated. More preferably, it is in the range of 0.02 to 1 times. When the value is less than 0.01, heat escapes to the main mold through the heat insulating layer because the heat insulating layer is too thin, so that the heat retaining effect is low, and rapid cooling and solidification on the mold surface can be suppressed. It will be difficult. On the other hand, if the value exceeds 2, on the contrary, the heat accumulated in the heat insulating layer from the thermoplastic resin during molding becomes difficult to escape to the main mold, and the time during which the heat insulating layer surface temperature decreases, that is, the cooling time becomes longer than necessary. It is not preferable because it becomes longer. still,
In the present invention, in the thickness of the heat insulating layer corresponding to the thickness of the molded product, within a range that does not substantially impair the object of the present invention,
It does not prevent some portions from exceeding the range specified in the present invention. As a part, 1 of the total area
The standard is 0% or less. As the thickness of the molded product, a thickness that can be generally molded by an injection molding method, a blow molding method, or the like can be used, but preferably the thickness of the molded product is 0.5 m
m to 20 mm is preferred.

In order to obtain a molded article having a good appearance which is the object of the present invention, it is required that the thermoplastic resin composition is brought into contact with the surface of the mold until the pressure during molding is sufficiently applied to the thermoplastic resin composition. It is necessary that the maximum temperature of the heat insulating layer surface temperature in the mold cavity be equal to or higher than the Tg of the thermoplastic resin, that is, the maximum temperature of the heat insulating layer surface during molding of the thermoplastic resin is determined by the thermoplastic resin composition. It is necessary to be in the range of Tg + 1 to Tg + 50 ° C. with respect to Tg of the product. Further, it is necessary that the surface temperature of the heat-insulating layer thereafter becomes lower than Tg. In the present invention, Tg means a glass transition temperature, and such a temperature is a value measured by DSC (differential scanning calorimetry) at a heating rate of 10 ° C./min. When the maximum temperature of the heat-insulating layer surface is lower than Tg + 1 ° C., the mold surface transferability of the mold is improved even if the injection pressure is sufficiently applied to the thermoplastic resin after the thermoplastic resin comes into contact with the mold surface. If the temperature exceeds Tg + 50 ° C., on the contrary, the thermoplastic resin comes into contact with the mold surface and then the molding pressure such as the injection pressure is sufficiently applied to the thermoplastic resin to transfer the mold surface. However, the cooling time required for cooling the molten thermoplastic resin to a temperature at which the molded article can be taken out of the mold increases, and the production efficiency decreases, which is not practical and not preferable.

The heat insulating mold of the present invention and the molding method using the same are intended for molding a thermoplastic resin composition, and the thermoplastic resin composition is not particularly limited. However, the effects of the present invention can be more preferably exerted in the case of a thermoplastic resin composition mainly containing an amorphous thermoplastic resin.

Here, the expression "mainly composed of an amorphous thermoplastic resin" means a case where at least the resin component in the composition is 100% by weight and the amount of the amorphous thermoplastic resin is 50% by weight or more. Examples of the amorphous thermoplastic resin include a styrene resin, an acrylic resin, a polycarbonate resin, an amorphous polyester resin, an amorphous polyarylate resin, a polyether sulfone resin, and a modified polyphenylene oxide resin. Examples of the styrene resin of the present invention include polystyrene, styrene / butadiene / styrene copolymer (SBS), hydrogenated styrene / butadiene / styrene copolymer (hydrogenated SBS), and hydrogenated styrene / isoprene / styrene copolymer (SEPS), impact-resistant polystyrene (HIPS), acrylonitrile / styrene copolymer (AS resin), acrylonitrile / butadiene / styrene copolymer (ABS resin), methyl methacrylate / butadiene / styrene copolymer (MBS resin),
Methyl methacrylate / acrylonitrile / butadiene / styrene copolymer (MABS resin), acrylonitrile / ethylene propylene rubber / styrene copolymer (A
(ES resin) or a mixture thereof.

The acrylic resin of the present invention contains methyl methacrylate as a main component, and is a polymer of methyl methacrylate alone or a copolymer thereof. Examples of the copolymer component of the copolymer include methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, octyl acrylate,
Acrylic alkyl esters such as 2-ethylhexyl acrylate, cyclohexyl acrylate, dodecyl acrylate, octadecyl acrylate, phenyl acrylate, and benzyl acrylate, and ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, amyl methacrylate, hexyl methacrylate, octyl methacrylate, 2- Examples thereof include alkyl methacrylates such as ethylhexyl methacrylate, cyclohexyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, phenyl methacrylate, and benzyl methacrylate.

The polycarbonate resin in the present invention is:
An aromatic polycarbonate resin obtained by reacting a dihydric phenol and a carbonate precursor by a phosgene method, a melting method, or an aromatic polycarbonate resin obtained by increasing the degree of polymerization of a prepolymer obtained by these methods by a solid phase polymerization method , And an aromatic polycarbonate resin obtained by reacting dihydric phenol with carbon monoxide and oxygen, or carbon dioxide in the presence of a palladium-based catalyst or the like, and a prepolymer obtained by such a method, It is an aromatic polycarbonate resin obtained by increasing the degree of polymerization by a method such as solid phase polymerization.
Examples of the dihydric phenol used here include 2,2-bis (4-hydroxyphenyl) propane (hereinafter referred to as bisphenol A), bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, 2,2- (4-hydroxy-3-
Methylphenyl) propane, bis (4-hydroxyphenyl) sulfone and the like. Preferred dihydric phenols are bis (4-hydroxyphenyl) alkanes, with bisphenol A being particularly preferred. Examples of the carbonate precursor include carbonyl halide, carbonyl ester, and haloformate, and specific examples include phosgene, diphenyl carbonate, and dihaloformate of a dihydric phenol. In producing the polycarbonate resin, the above dihydric phenols may be used alone or in combination of two or more, and the polycarbonate resin is a branched polycarbonate resin obtained by copolymerizing a trifunctional or higher polyfunctional aromatic compound. Or a mixture of two or more polycarbonate resins.

The thermoplastic resin composition according to the present invention includes:
It also includes a single thermoplastic resin.

The heat-insulating mold of the present invention imparts a smoother surface to the surface of the heat-insulating layer, or a fine pattern, unevenness, or the like, which tends to be insufficient with only three-dimensional molding, as compared with the heat-insulating layer alone. A metal layer may be provided for the purpose. The metal layer can be formed by a method such as chemical plating and / or electroplating or a method of attaching a metal plate directly to the heat insulating mold. Furthermore, it is also possible to provide fine patterns and irregularities on the metal layer. The thickness of the metal layer is not particularly limited.
It is preferable that the thickness be 0 μm or less. If the thickness exceeds 100 μm, the effect of the heat-insulating layer is diminished, and the temperature of the mold surface in a portion requiring high appearance is unlikely to become high. Particularly, a thickness of 2 to 50 μm is preferable.

The heat-insulating mold and the molding method using the same according to the present invention can be used mainly for injection molding and blow molding, and special molding methods such as gas-assist molding, injection compression molding and ultra-high-speed injection molding. The same can be used in the injection molding method.

[0038]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be further described below with reference to examples. The thermoplastic resin used in the examples, the respective molds, and the three-dimensional molding method and the formed heat insulating layer are as follows. Thermoplastic resin: Glass fiber 30% reinforced aromatic polycarbonate resin Tg: 149 ° C. (A polymer of bisphenol A, viscosity average molecular weight of aromatic polycarbonate resin 23,500) Main mold: Steel material (S55C) Thermal conductivity 20 W / m · K Three-dimensional modeling: Stereolithography device SOLIFORM-500A (Teijin machine) Thermal insulation layer: Photo-curable resin TSR-753 (Teijin machine) Thermal conductivity 0.50 W / m · K

[Examples 1 to 3 and Comparative Examples 1 to 5] (1) Molding of Samples The nested door handle mold shown in FIGS. FIG. 5 shows a heat-insulating layer having the thickness shown in Table 1 subjected to chemical plating.
Using a heat-insulating mold incorporated in the manner shown in FIG. 7, a glass fiber 30% reinforced polycarbonate resin was molded using an injection molding machine [Sumitomo Heavy Industries, Ltd. SG-150U].
The door handle molded products shown in FIGS. 1 to 4 were molded at each cylinder temperature, mold temperature, and molding cycle shown in FIG. The production of such a heat insulating layer was possible within 5 hours in all cases. Also, in the weld part of the weld dumbbell mold that generates weld in the center of the tensile test piece,
Using a heat-insulating mold that incorporates the heat-insulating layer shown in Table 1 produced by stereolithography and subjected to chemical plating,
Weld test pieces having the thickness of the molded product shown in Table 1 were prepared.
A dumbbell molded product with a weld filled from both ends of the mold and a dumbbell molded product without a weld filled with resin from one end were molded, and the weld strength retention was calculated. Also in this case, such a heat insulating layer could be manufactured within 5 hours in all cases. In addition, the case where the heat insulating layer is 0 mm in the table indicates a case where the above-mentioned molded article is formed using a mold having no heat insulating layer.

(2) Measurement of Surface Temperature of Heat Insulating Layer The maximum temperature of the surface temperature of the heat insulating layer was measured using a thermocouple in contact with the surface of the mold from the back side of the heat insulating layer.

(3) Measurement of Transferability (Surface Roughness) The handle design surface of the door handle molded product was measured using a three-dimensional surface roughness shape measuring machine (Surfcom 1400A-3DF manufactured by Tokyo Seimitsu).
-12) was used to measure the surface roughness (center point average value). The surface roughness is preferably 0.2 μm or less.

(4) Weld strength (retention rate of tensile strength) Tensile strength is measured using a dumbbell molded product with a weld and a dumbbell molded product without a weld, and the tensile strength retention with or without a weld is calculated according to the following equation (1). did. The tensile strength retention is preferably 80% or more.

[0043]

(Equation 1)

(5) Molding cycle In injection molding of a door handle molded product, after injection filling with a thermoplastic resin, the molded product is cooled to a temperature at which the molded product can be taken out of the mold (Tg of the thermoplastic resin or less). The time required to remove the article was measured. In the present sample, a molding cycle of 100 seconds or less is practical and preferable without reducing the production efficiency.

[0045]

[Table 1]

As shown in Table 1, Examples 1 to 3 have extremely small surface roughness and excellent transferability, and are excellent in weld strength, as compared with Comparative Examples 1 to 3. . That is, it is understood that it is necessary to have a specific heat insulating layer thickness. Further, when the mold temperature was increased without providing the heat insulating layer as shown in Comparative Example 4, and when the maximum temperature of the heat insulating layer surface exceeded 50 ° C. as shown in Comparative Example 5, the molding cycle became very long, Comparative Example 4
Also in comparison with Nos. To 5, it can be seen that the molding cycle is short and practical and preferable without reducing the production efficiency.

[0047]

According to the heat-insulating mold of the present invention, a high appearance can be achieved even in a complicated three-dimensional shape, and a molded product having excellent transferability, glossiness and high weld strength can be obtained even in a complicated shape. Since it is possible to produce the heat insulating layer, which has been difficult to produce conventionally, in a short period of time and at low cost, its industrial value is extremely large.

[Brief description of the drawings]

FIG. 1 is a side view schematically showing a door handle molded product which is one of evaluation samples.

FIG. 2 is a front view schematically showing a door handle molded product which is one of the evaluation samples.

FIG. 3 is a schematic view (a side view of the short side of the mounting arm) of a door handle molded product, which is one of the evaluation samples, taken along a dashed line in FIG.

FIG. 4 is a rear view schematically showing a molded door handle, which is one of the evaluation samples.

FIG. 5 is a front view schematically showing a door handle nest portion in the door handle molding die. The nest is attached to the fixed side of the mold to perform molding.

FIG. 6 is a side view schematically showing a door handle nesting portion. The nest is formed of the same steel material as the mold.
The nested portion has a spacer made of a mold steel material, and then has a heat insulation layer formed by optical molding and plated, and furthermore, a fixing frame made of the mold steel material is screwed into the nest to form a nested portion. Fixed to

FIG. 7 is a perspective view showing an outline of a relationship between a spacer, a heat insulating layer, and a fixed frame. The spacer has a structure that can be fixed with screws at the top of the fixing frame.

[Explanation of symbols]

Reference Signs List 1 Door handle main body, one of evaluation samples 2 Handle design surface of door handle (heat insulating layer is installed on corresponding part of mold) 3 One-dot chain line indicating cut surface 4 Mold fixing side nesting main body 5 Heat insulating layer And a fixing frame for fixing the spacer (same material as the mold steel material) 6 Spacer (same material as the mold steel material, dark tone portion) 7 Thermal insulation layer created by stereolithography (light tone portion) 8 Fixed frame Screws and screw holes for fixing 9 Screws and screw holes for fixing spacer

Claims (7)

[Claims] 1. A heat insulating layer is incorporated in a main mold of a mold used for molding a thermoplastic resin composition, and the main mold is held at a temperature lower than Tg of the thermoplastic resin composition. A heat insulating mold used in a molding method in which a maximum temperature of a mold cavity surface temperature of a part in which a layer is incorporated during molding is in a range of Tg + 1 to Tg + 50 ° C. The thickness of the heat insulating layer is in the range of 0.01 to 2 times the thickness of the molded product, and the heat insulating layer is formed by a three-dimensional forming method, and has a thermal conductivity of 1.0 W / m · K or less. A heat insulating mold comprising a heat insulating layer made of a resin composition. 2. The heat insulating mold according to claim 1, wherein the three-dimensional forming method is an optical forming method. 3. A heat insulating layer having a metal layer on a surface thereof.
Or the heat-insulating mold according to any one of 2. 4. The heat insulating mold according to claim 3, wherein the metal layer is formed by chemical plating and / or electroplating. 5. The heat-insulating mold according to claim 1, wherein the thermoplastic resin composition is a resin composition mainly composed of an amorphous thermoplastic resin. 6. A molding method for obtaining a molded article having a high appearance portion, using the heat-insulating mold according to any one of claims 1 to 5. 7. The thermoplastic resin composition according to claim 7, wherein the main mold of the mold is a thermoplastic resin composition.
g is maintained at a temperature lower by 20 to 60 ° C., and the maximum temperature at the time of molding the part where the heat insulating layer is incorporated is:
The molding method for obtaining a molded article having a high appearance portion according to claim 6, wherein the molding is performed under a condition of reaching Tg + 10 to Tg + 30 ° C.