JPH1067045A - Manufacture of thermoplastic resin molded product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a molded product excellent in heat resistance and appearance and satisfying various physical properties such as impact resistance, mechanical strength or the like by thermally molding a sheet composed of a thermoplastic resin to form a first molded product and subsequently inserting the first molded product into a male mold to subject the same to heat shrinkage treatment. SOLUTION: A first molded product larger than a final shape obtained from a sheet by thermal molding is molded by pressure forming, vacuum molding or plug molding. The plug molding method is most pref. from an aspect capable of uniformly performing heat shrinkage in a next process. After first stage molding, the molded product is thermally shrunk at high temp. to perform orientation crystallization and the removal of strain. A male mold is inserted in the first molded product and the molded product is heat-treated to be shrunk to form a second molded product. The male mold is especially pref. formed into the shape of the second molded product being a final shape and, if vacuum molding or pressure molding is performed while heat shrinkage is performed in succession to heat shrinkage, a desired shape is easily obtained. As a result, mechanical strength such as heat resistance and shock resistance or the like are made excellent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a thermoplastic resin molded article having excellent heat resistance and impact resistance.

[0002]

2. Description of the Related Art Molded articles made of a thermoplastic resin sheet are:
Since it can be processed into various shapes, it is used for various purposes. For example, molded articles made of a polyester sheet are excellent in thermoformability, gas barrier properties, mechanical strength, and the like, and are widely used for packaging containers such as cups and trays. However, since the polyester has a low secondary transition point, such a molded article has poor shape stability at high temperatures, and has a drawback that it is deformed when exposed to a temperature of, for example, about 60 to 100 ° C. In order to solve such problems, various methods have been conventionally attempted. But those results were not always satisfactory. For example,
Japanese Patent Publication No. 44-5108 discloses that after a polyethylene terephthalate film is formed, it is placed in a molding die at 140-2.
There is disclosed a method for improving heat resistance by crystallizing a molded article by heat treatment at a temperature of 20 ° C. However, this method has a drawback that the molded article is deformed during the heat treatment and the impact resistance of the obtained molded article is reduced. It is presumed that the decrease in the impact resistance here is caused by the fact that the polyethylene terephthalate crystals tend to be spherulite in the heat treatment by this method, so that the molded product becomes brittle.

[0003] Further, after thermoforming an unstretched polyester sheet, the molded article is heat-treated in a mold at a low temperature range such as 60 to 140 ° C to remove the distortion without crystallizing the molded article. Although a method is conceivable, this method is not a satisfactory method because the effect of improving heat resistance is small. Also, JP-A-54-43971, JP-A-54-43971
No. 43972, JP-A-55-17516, etc., after biaxially stretching and orienting a polyester sheet,
A method of thermoforming and heat treating the obtained molded article is disclosed. Among these methods, when a sheet with a low degree of orientation is molded, the effect is small, while when a sheet with a high degree of orientation is molded, the appearance of the molded article becomes poor due to poor deep drawing formability. . Thus, attempts by these methods have not always yielded satisfactory results. Further, JP-A-50-21051 discloses that an unstretched polyester sheet is heated at 70 to 100 ° C.
After stretching 1.5 to 3.0 times in the uniaxial direction within the temperature range described above, heat-shrink it in hot water at 90 or 95 ° C., then heat mold, and then heat it in a mold at 130 ° C. or 150 ° C. Discloses a method of heat setting.

Japanese Unexamined Patent Publication (Kokai) No. 61-254326 discloses that an unstretched polyester sheet is 1.5 to 3.0 biaxially in a temperature range of 70 to 100 ° C. using a simultaneous biaxial stretching machine. A method is disclosed in which after being double-stretched, heat-shrinked in a temperature range of 70 to 120 ° C, pressure-formed at 80 to 100 ° C, and then heat-set at a temperature of 180 to 250 ° C in a mold. However, in these methods, problems such as poor appearance of the molded article due to inferior deep draw formability of the sheet, a small improvement effect of heat deformation, and a decrease in impact resistance of the molded article. However, these methods have not always yielded satisfactory results.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems, and provides a thermoplastic resin which is excellent in heat resistance and appearance of a molded product and satisfies various physical properties such as impact resistance and mechanical strength. It is intended to provide a manufacturing method for obtaining a resin molded product.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in view of the above problems, and as a result, have once made a molded product larger than the desired shape, and then inserted a male mold into the molded product. The present inventors have found that the above-mentioned problems can be solved at once by a novel manufacturing method of shrinking a molded article by heat shrinking, and completed the present invention. In other words, the gist of the present invention is that a sheet made of a thermoplastic resin is thermoformed into a first molded product, and then a male mold is inserted into the first molded product and subjected to a heat shrinkage treatment, thereby reducing the size of the first molded product. A method for producing a thermoplastic resin molded product characterized by obtaining a second molded product having a capacity. The thermoplastic resin to which the method of the present invention is applied is not particularly limited as long as the sheet can be used for thermoforming, but polyester, polypropylene and polyamide which are oriented crystalline thermoplastic resins are preferable. Particularly preferred is a polyester resin.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The polyester used in the present invention is a polyester obtained by using an aromatic dicarboxylic acid or an ester thereof and a glycol as main raw materials. As the aromatic dicarboxylic acid, terephthalic acid is mentioned as a typical example. In addition to terephthalic acid, 2,6-naphthalenedicarboxylic acid, isophthalic acid, phthalic acid, oxycarboxylic acid (for example, p-oxyethoxybenzoic acid, etc.) And the like, preferably terephthalic acid and 2,6-naphthalenedicarboxylic acid. On the other hand, as the glycol, ethylene glycol is mentioned as a typical example. In addition to ethylene glycol, diethylene glycol, 1,4- and 1,3-cyclohexanedimethanol, propylene glycol, 1,4-butanediol,
It is possible to use one or two or more of neopentyl glycol, bisphenol A and bisphenol S, and preferably ethylene glycol, diethylene glycol, and 1,4-cyclohexanedimethanol.

[0008] In the present invention, not only that the improvement effect of the present invention can be largely exhibited, but also that the raw materials are inexpensive,
From the viewpoints of easy handling under drying conditions and molding conditions, and excellent physical properties of the finally obtained molded product, it is preferable to use 8
A polyester in which 0 mol% or more, more preferably 80 to 99 mol%, particularly preferably 85 to 97 mol%, is an ethylene terephthalate unit is preferred. When the ethylene terephthalate unit is less than 80 mol%, the handling becomes difficult due to the occurrence of fusing at the time of drying, the impact resistance and the rigidity of the obtained molded product are deteriorated, and the present invention is at the forefront. The effect of improving the heat resistance, which is the effect of improvement, is not preferable because it is too small. On the other hand, when the ethylene terephthalate unit exceeds 99 mol%, when the molding method of the present invention is used, the crystallization rate is high and spherulites are easily formed, so that the spherulites become brittle and the impact resistance is liable to decrease, which is not preferable.

Further, a preferred polyester composition for achieving the object of the present invention is a diglycol component such as diethylene glycol and 1,4-
Mixing cyclohexane dimethanol is mentioned. Each content is preferably 0.5 to 1
A range of 0 mol%, more preferably a range of 1 to 5 mol%, is recommended. By blending such a copolymer component and setting the amount of ethylene terephthalate unit in the polyester to a specific value, without significantly impairing the physical properties of the molded product, the deep drawing processability is dramatically improved, and the improvement effect of the present invention is obtained. Can be fully demonstrated. The polyester having such a composition is produced by melt polymerization and / or solid state polymerization according to a known method. Known catalysts, esterification or transesterification catalysts, polymerization catalysts or stabilizers for the production of polyester can be used by known methods. In addition, a lubricant, an antistatic agent and other known additives can be used at any stage during the polymerization. The degree of polymerization of the polyester is selected so as to give the sheet used in the method of the present invention and the obtained molded article an intrinsic viscosity in a desired range described later.

The intrinsic viscosity of the resin of the polyester sheet used in the present invention and the molded product obtained from the polyester sheet is 0.5 to 0.5.
It is preferably in the range of 1.3 dl / g,
Particularly preferred is a range of 1.1 dl / g. In addition, the limiting viscosity is phenol / tetrachloroethane = 50.
/ 50 (weight) in a mixed solvent at 30 ° C. When the intrinsic viscosity is less than 0.5 dl / g, not only the mechanical properties of the molded article obtained in the present invention, particularly the impact resistance and the like are poor, but also the deep drawability is not preferable. On the other hand, when the intrinsic viscosity exceeds 1.3 dl / g, the melt fluidity is inferior, so that it becomes difficult to process the sheet as the material of the molded article, or the drawback that the deep drawability becomes inferior. Therefore, it is not preferable.

The method of the present invention is preferably applied to polypropylene and polyamide in addition to polyester. Examples of the polypropylene used in the present invention include propylene homopolymer, and copolymers of propylene as a main component and other α-olefins such as ethylene, butene, hexene, 4-methylpentene, and octene as auxiliary components. it can. Most preferred is a propylene homopolymer, but among polymers, a copolymer of propylene and 40% by weight or less of another α-olefin is preferred, and further, 30% by weight or less,
Particularly, a copolymer with 20% by weight or less of ethylene or butene is preferable. The copolymer may be a random copolymer or a block copolymer. These polypropylenes can be used alone or as a mixture of a plurality.

As the polyamide, a ring-opened polymer of a lactam having three or more ring members, a polycondensate of an ω-amino acid, a polycondensate of a nylon salt composed of a diamine and a dibasic acid, and the like can be used. Examples of the lactams include ε-caprolactam, ω-caprylactam, ω-enantholactam, ω-laurolactam, α-pyrrolidone, α-piperidone, and the like.Examples of ω-amino acids include ω-amino Heptanoic acid, ω-aminoundecanoic acid and the like, and examples of the diamine constituting the nylon salt include hexamethylene diamine, nonamethylene diamine,
Undecamethylenediamine, dodecamethylenediamine,
Examples include meta-xylylenediamine and the like, and examples of the dibasic acid include adipic acid, sebacic acid, dodecane diacid, terephthalic acid, isophthalic acid, glutaric acid and the like. The polyamide may be either a homopolymer or a copolymer, and is typically nylon 4, 6, 7, 8, 1
1, 12, 66, 69, 610, 612, 6T, 6I,
6/66, 6/12, 6 / 6T, 6I / 6T and the like.

In the present invention, whitening particles may be added to the sheet in an amount of 0.1% in order to color the sheet material such as white.
10 to 10% by weight, more preferably 0.5 to 7% by weight. As such particles, titanium oxide, calcium carbonate and barium sulfate are preferred. The addition of such particles is preferable because it makes it possible to obtain a molded article made of a thermoplastic resin that hardly deteriorates the physical properties of the molded article and satisfies beautiful whitening and hiding degree. The average particle size of the particles is not particularly limited, but is preferably 100 μm or less, more preferably 10 μm, in consideration of the appearance of the molded article.
It is as follows. When the content of the particles is less than 0.1% by weight, the whiteness and hiding degree of the finally obtained molded product are insufficient, and when the content is more than 10% by weight, the deep drawability and In addition, the physical properties of the molded article such as impact resistance and rigidity are deteriorated, which is not preferable.

Further, depending on the use of the molded product, it is also a preferable embodiment to color the molded product in various colors. Although the coloring method is not particularly limited, a dry color in which a coloring material such as a dye or a pigment is dispersed in a resin using a solid dispersant,
Paste color in which the color material is dispersed in the resin using a liquid dispersant, liquid color in which the color material is dispersed in the resin using a high-boiling liquid dispersant, and several tens of final concentrations of the color material in the resin. Masterbatches dispersed at twice the concentration are known. Of these, coloring using a master batch is preferred because of good dispersibility in the resin and easy handling during compounding. The coloring material is not particularly limited, and can be arbitrarily selected from various dyes, organic pigments, inorganic pigments, and the like, dispersibility in a resin, dispersibility of a coloring agent itself, weather resistance, heat stability, hygiene and The selection may be made in consideration of the cost and the like. In addition, various additives such as an antioxidant, an ultraviolet absorber, a flame retardant, and a lubricating agent are appropriately compounded in addition to the whitening material, the concealing material, and the coloring material.
Furthermore, various surface treatments for the purpose of preventing scratches on the surface and preventing static charge, and the like, coating with a protective sheet, and the like may be performed.

It should be noted that other thermoplastic resins such as polycarbonate and polyolefin may be blended as the third component within a range satisfying the constitutional requirements of the present invention. The content is preferably not more than 30% by weight of the whole.
The content is more preferably 0% by weight or less, particularly preferably 10% by weight or less. When the amount exceeds 30% by weight,
For the purpose of the present invention, it is difficult to express the excellent physical properties inherent to polyester and the like, which is not preferable.
Furthermore, it is preferable to mix a recycled product generated in the process or the like with such a thermoplastic resin material as polyester, not only in terms of cost but also in terms of reduction of waste. In the present invention, such a recycled product may be blended as long as it does not exceed the gist of the present invention.

The method for producing a sheet from a thermoplastic resin is not particularly limited. For example, after drying a raw material such as polyester by a conventional method, by using an extruder, preferably extruded at a resin temperature in the range of 200 to 320 ° C,
Cool and solidify on the casting drum to form a sheet. In addition, it is one of the preferable manufacturing processes that the extruder is provided with a vent so that the drying step is omitted or the drying time is shortened. Also, near the casting drum,
It is also a preferable manufacturing method to equip one or more touch rolls and use the touch rolls as holding rolls at the time of processing and manufacturing a sheet. As a matter of course, the sheet used in the present invention may be a laminate of two or three or more layers as long as it does not exceed the gist of the present invention. A recycled product may be introduced into the various surface treatments, the coating of the protective sheet, and the inner layer.

The thermoplastic resin raw material, sheet and molded product in the present invention preferably have the following thermal properties.
That is, after the thermoplastic resin is melted and quenched, the heating rate is 20
The temperature rise crystallization temperature (Tcc) measured in ° C./min is (Tm
[Melting point] -140) to (Tm-20) C, preferably (Tm-120) to (Tm-30) C. Tcc is (Tm-14
0) When the temperature is lower than 0 ° C., the crystallization rate is too high, so that when produced by the novel molding method of the present invention, the impact resistance decreases, which is not preferable. On the other hand, Tcc is (Tm−2
0) When the temperature exceeds 0 ° C., the crystallization speed is too slow, and the effect of improving the heat resistance, which is the most important object of the present invention, is not preferable.

The average thickness t ₀ of the thermoplastic resin sheet used in the present invention is preferably in the range of 0.1 to 10 mm, particularly preferably in the range of 0.2 to 10 mm. If the average thickness t _{0 of} such a sheet is less than 0.1 mm, the resulting molded article is not preferable because it has poor impact resistance and rigidity, and the effect of improving heat resistance is too small. Conversely, when the average thickness t ₀ exceeds 10 mm, it is not only disadvantageous in terms of cost, but also, for example, in that the deep drawability and the lightness are inferior, and therefore, it is not preferable.

Next, a novel molding method which is the gist of the present invention will be described. The conventional air / vacuum forming method is a method of forming into a target shape in one step. On the other hand,
The novel molding method of the present invention is a molding method in which a molded product having a size larger than a target shape is once formed, then heat-shrinked into a target product having a desired shape, and then formed into a target shape. Hereinafter, the molding method will be described. First, as a first step, a first molded product larger than the final shape is formed from a sheet by thermoforming. It is preferable that the first molded article is formed by air pressure molding, vacuum molding or plug. Molding with a plug is a method of elongating and molding a sheet only with a plug. According to studies by the present inventors, the method of molding with a plug can uniformly perform heat shrinkage in the next step. Most preferred in that respect. The plug is preferably of a shape that can be uniformly stretched. For example, a conical plug with a rounded tip is recommended. It is also a preferable embodiment to form the first molded article by molding with a plug and then performing free blow, that is, pressure molding without using a mold.

[0020] The first molded article, the average of the thermoplastic resin sheet thickness t _0, the thickness ratio when the average thickness t ₁ of the first molded article,

It is preferable that the size be in the range of 1.5 ≦ t ₀ / t ₁ ≦ 15 (1), more preferably 3 to 15, and further preferably 5 to 15. .
When the thickness ratio t ₀ / t ₁ is less than 1.5, the molecular orientation by stretching is too small, so that the effects of improving heat resistance and impact resistance, which are the effects of the present invention, are too small, or the thickness of the molded product is small The spots are poor, which is not preferable. On the other hand, when t ₀ / t ₁ exceeds 15, the molecular orientation by stretching is too large, so that the moldability of the heat-shrinkable molded article in the next step is poor, and the appearance of the finally obtained molded article is poor. Is not preferred because Note that t ₀ / t ₁ is considered to be a numerical value closely related to the area stretching ratio in the first-stage molding.

The molding temperature of the first stage is (Tg + 8) when the glass transition point (Tg) of the thermoplastic resin is −10 ° C. or more.
0) C or lower is preferable, and Tg to (Tg + 60) C
Is more preferable. In addition, this stretching temperature means the surface temperature of a sheet or molded article confirmed by a radiation thermometer or the like. In the next step in the molding method of the present invention, a male mold is inserted into the first molded article, and the molded article is heat-treated and shrunk to obtain a second molded article. Here, the average thickness of the second molded article thickness ratio of t ₁ when it is t ₂

## EQU4 ## It is preferable that the range is 0.1 ≦ t ₁ / t ₂ ≦ 0.9 (2). When t ₁ / t ₂ is less than 0.1, the amount of shrinkage is too large, and the shape and appearance of the obtained molded product are unfavorably deteriorated. on the other hand,
If t ₁ / t ₂ exceeds 0.9, the effect of improving heat resistance is too small to be suitable. Incidentally, still more preferably in the range of t ₁ / t ₂ is 0.2 to 0.8, particularly preferred range is 0.2 to 0.7.

The temperature of the heat treatment in this step is preferably not more than the melting point (Tm) of the thermoplastic resin and not less than (Tm-140) ° C, more preferably from (Tm-120) ° C to Tm, and more preferably (Tm-140). 100) The range from 100C to Tm is particularly preferred. When the heat treatment temperature is lower than (Tm-140) ° C, the effect of improving the heat resistance aimed at by the present invention is too small.
If the heat treatment temperature exceeds Tm, the impact resistance of the finally obtained molded product is deteriorated, which is not preferable. In addition, this heat treatment temperature means the surface temperature of the molded article confirmed by a radiation thermometer or the like.

It is particularly preferable that the male mold has the shape of the second molded product which is the final shape. If the male mold is vacuum-formed or air-pressed with a male mold while performing heat shrinkage or subsequent to heat shrinkage, the desired shape can be obtained. This is a particularly preferable mode because it can be easily shaped. The feature of the novel molding method of the present invention is that heat shrinkage is performed at a high temperature after the first stage molding, orientation crystallization and strain removal are performed, thereby realizing improvement in heat resistance and impact resistance. Therefore, by applying the production method of the present invention, a thermoplastic resin molded product having excellent physical properties, particularly, dramatically improved heat resistance can be obtained. The method of the present invention is applicable to any method for producing a molded article formed from a sheet.

[0024]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the scope of the invention. The methods and definitions for measuring various physical properties and characteristics in the examples are as follows. In the examples and comparative examples, “parts” means “parts by weight”.

(1) Intrinsic viscosity 1.00 g of phenol / tetrachloroethane = 50/50 was arbitrarily sampled from a thermoplastic resin sheet and a molded product.
(Weight ratio) in 100 ml of mixed solvent
Was measured. (2) Copolymerization component: Determination of diethylene glycol (DEG) and cyclohexane dimethanol (CHDM) Arbitrarily sampled from a thermoplastic resin sheet and a molded product, hydrolyzed by a conventional method, and the generated diol component was quantified by gas chromatography. . (3) Melting point (Tm) 10 mg was arbitrarily sampled from a thermoplastic resin sheet and a molded product, melted in nitrogen at 300 ° C. for 3 minutes, and quenched with dry ice. The quenched product was measured from a temperature of 20 ° C./20° C./min using a DSC 20 model manufactured by Seiko Denshi, and Tm (peak temperature) was determined.

(4) Glass transition point (Tg) 10 mg was arbitrarily sampled from a thermoplastic resin sheet and a molded product, melted in nitrogen at 300 ° C. for 3 minutes, and quenched with dry ice. The quenched product was measured from a temperature of 20 ° C. at a heating rate of 20 ° C./min using a DSC 20 model manufactured by Seiko Denshi to determine a secondary transition temperature (Tg). (5) Temperature rise crystallization temperature (Tcc) 10 mg was arbitrarily sampled from a thermoplastic resin sheet and a molded product, melted in nitrogen at 300 ° C. for 3 minutes, and quenched with dry ice. The quenched product was measured from a temperature of 20 ° C. at a temperature rising rate of 20 ° C./min using a DSC 20 model manufactured by Seiko Denshi to determine Tcc (peak temperature). (6) Average thickness (t ₀ , t ₁ , t ₂ ) The thickness of the thermoplastic resin sheet and the molded product was measured every 5 mm, and the average value was defined as the average thickness in the present evaluation. In the measurement of the average thickness of the molded product, the ear portion, which is the unstretched portion of the molded product, is not included in the average thickness.

(7) Evaluation of Molded Articles-Deep Drawing Formability The appearance of the obtained 20 molded articles was visually evaluated based on the following judgment criteria. ：: No problem as a product. X: The product cannot be used as a product due to poor appearance such as a part of the aperture being insufficient and / or wrinkles or breakage. Δ: Intermediate situation between the above ○ and ×.・ Heat resistance; heat deformation test The obtained molded product was placed in a hot air oven set at 90 ° C for 3 hours.
The mixture was heated for a minute. Next, at 23 ° C, 65% RH
After being left in the atmosphere for one hour, the appearance of the molded article was visually observed according to the following criteria. The heat resistance was evaluated by repeating this operation 20 times. ：: No significant difference from the shape before heat treatment. ×: The shape is clearly different from the shape before the heat treatment and the appearance is poor, and it is judged that the product cannot be used. Δ: Intermediate situation between the above ○ and ×.

Example 1 In an esterification reaction tank, 87 parts of terephthalic acid and 65 parts of ethylene glycol were added under atmospheric pressure for 250 parts under the presence of 100 parts of bis (β-hydroxyethyl) terephthalate oligomer.
C., and the esterification reaction was performed. Five hours after the start of the reaction, a polyester oligomer having an esterification rate of 96% was obtained. In this reaction system, ethyl acid phosphate was added.
012 parts, and magnesium acetate tetrahydrate 0.08
Parts and 0.04 part of antimony trioxide, and the temperature was gradually increased from 220 ° C. to 285 ° C., and 1 mm from normal pressure.
Hg, followed by a polycondensation reaction at 285 ° C. and 1 mmHg for 4 hours and 30 minutes.
A polyester having 68 dl / g, Tg of 80 ° C and Tm of 254 ° C was obtained. This polyester was dried under vacuum at 160 ° C. for 4 hours, and melt-extruded at a resin temperature of 290 ° C. to obtain a sheet having a thickness of 1.0 mm. This sheet is 200m
After cutting into a size of mx 200 mm, molding by the method of the present invention,
The heat resistance was evaluated. The heating of the sheet and the molded article in each step was mainly performed using an infrared heater.

First, the first stage was formed using a conical plug with a rounded tip. Here, the shape of the sheet to be molded is a circle having a diameter of 100 mm, and the depth direction of the plug is 180.
mm. Other molding conditions and results are shown in Table 1. Next, a male mold was inserted into the molded product. Here, the male mold has a cylindrical shape with an outer shape of 100 mm in diameter and 50 mm in depth, and has a surface temperature of 40 ° C. by water cooling. While heat-treating this molded product to 200 ° C. to shrink it into a desired shape, the male mold was evacuated, and the second-stage molding was performed by heat-shrinking treatment and vacuum molding. Other molding conditions and results are shown in Table 1. The shape of the obtained molded product was very good, and the results of the heat resistance test confirmed that the physical properties were improved. The results are shown in Table 1.

Example 2 In the first stage molding in Example 1, after molding with a plug, air pressure molding, that is, free blow was performed without using a mold. Except that, the molding was performed in exactly the same manner as in Example 1. The results are shown in Table 1.

COMPARATIVE EXAMPLE 1 The polyester sheet used in Example 1 was vacuum-formed in a single step by a straight method using a cylindrical female mold having an inner shape of 100 mm in diameter and a depth of 50 mm. went. The surface temperature of the mold was set to 40 ° C. by water cooling. Other molding conditions and results are shown in Table 1. In addition, when the molding temperature was set to the same as that in Example 1, only a poor appearance of the molded product was obtained. Although the shape of the obtained molded article was not a problem, the evaluation result of the heat resistance test was at a level that was not practical.

[0032]

[Table 1]

[0033]

The method for producing a molded article according to the present invention is an epoch-making method for improving the heat resistance of the molded article without impairing the inherent properties of the thermoplastic resin sheet. Furthermore, since the thermoplastic resin sheet is stretched and molded and then heat-shrinked, orientation crystallization and strain removal are performed, and a molded product having not only heat resistance but also excellent mechanical strength such as impact resistance is obtained. Can be The method of the present invention is applicable to the production of any molded article using a sheet.

Claims (11)

[Claims] 1. A first molded product having a shape larger than a target shape is obtained by thermoforming a thermoplastic resin sheet, and a second molded product is obtained by inserting a male mold into the first molded product and thermally shrinking the molded product. A method for producing a thermoplastic resin molded article, characterized by the following. 2. The method for producing a thermoplastic resin article according to claim 1, wherein the first molded article is obtained by molding the thermoplastic resin sheet by air pressure molding, vacuum molding or plugging. 3. The method for producing a thermoplastic resin article according to claim 1, wherein a first molded article is obtained by molding the thermoplastic resin sheet with a plug. 4. The first molded product obtained by molding a thermoplastic resin sheet with a plug and then performing pressure molding without using a mold to obtain a first molded product. Production method of thermoplastic resin molded products. 5. The method according to claim 1, wherein a male mold is inserted into the first molded article, and the second molded article is obtained by pressurized air or vacuum forming while heat shrinking or after heat shrinking. 3. The method for producing a thermoplastic resin molded product according to claim 1. 6. Any ratio between the average thickness t ₁ of the average thickness t ₀ of the thermoplastic resin sheet first molded article according to claim 1 to 5, characterized in that the range of the following formula (1) 3. The method for producing a thermoplastic resin molded product according to claim 1. [Expression 1] 1.5 ≦ t ₀ / t ₁ ≦ 15 (1) 7. The method according to claim 1, wherein the ratio of the average thickness t ₁ of the first molded product to the average thickness t ₂ of the second molded product is in the range of the following formula (2). The method for producing a thermoplastic resin molded article according to the above item. [Expression 2] 0.1 ≦ t ₁ / t ₂ ≦ 0.9 (2) 8. A thermoplastic resin sheet is thermoformed at a temperature of (glass transition point of the thermoplastic resin−10) ° C. to (glass transition point of the thermoplastic resin + 80) ° C. to obtain a first molded article. The method for producing a thermoplastic resin molded product according to any one of claims 1 to 7, wherein: 9. The molded article according to claim 1, wherein the first molded article is thermally shrunk at a temperature of from the melting point of the thermoplastic resin to (melting point−140) ° C. to form a second molded article. The method for producing the thermoplastic resin molded article according to the above. 10. The method for producing a thermoplastic resin molded article according to claim 1, wherein the thermoplastic resin is selected from polyester, polypropylene and polyamide. 11. The thermoplastic resin has a repeating unit of 80.
The method for producing a thermoplastic resin article according to any one of claims 1 to 10, wherein at least mol% is a polyester comprising ethylene terephthalate units.