JP2002047361A - Heat-resistant polyester sheet and molded article from the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyester sheet which has good transparency and moldability, capable of sterilizing at a high temperature and filling at a high temperature has the heat-resistance to an electronic oven, and the strength endurable to pile up during a goods display, and to provide a molded article from the same. SOLUTION: The polyester sheet is composed of a polyester resin composition containing a polyester resin (A) which comprises dicarboxylic acid component having an unit of terephthalic acid as a main component and a glycol component having an unit of tetramethylene glycol as a main component and a polyester resin (B) which comprises a dicarboxylic acid component having an unit of terephthalic acid as a main component and a glycol component having an unit of ethylene glycol as a main component. The polyester sheet has an initial haze not more than 10% in a thickness of 200 μm and a change in the haze between after heat-treatment at 140 deg.C for 30 minutes and the one after heat- treatment at 140 deg.C for 30 minutes not more than 20%, and a tensile elastic modulus not less than 700 MPa. The molded article from the same is also provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a polyester sheet or molded article. More specifically, the present invention relates to a polyester sheet or molded article having good transparency, moldability, heat resistance, and strength.

[0002]

2. Description of the Related Art Polyester resins represented by polyethylene terephthalate have excellent physical properties such as mechanical properties and chemical resistance, and are widely used in fibers, packaging films, food bottles, medical containers and the like. . Above all, in the field of food containers, the use of vacuum molded products such as small beverage bottles, blister packs, and cup-shaped injection molded products has been remarkably expanding. Resins used as applications for these food containers are required to be pasteurized at 80 ° C. or higher and filled at high temperature in order to ensure hygiene. When used in a microwave oven, 14
High heat resistance of 0 ° C. is required. Furthermore, high strength that can withstand the load when the containers are stacked is required. However, the glass transition point of polyethylene terephthalate is 67
Because it is ~ 81 ° C, containers made of polyethylene terephthalate cannot be sterilized at high temperature or filled with high temperature,
Also, it could not be used for microwave oven containers. On the other hand, as disclosed in JP-A-59-5019, a so-called C which is molded in a high-temperature mold and crystallized at a higher temperature while maintaining the molded shape to realize high heat resistance. -PET has been proposed. However, the C-PET
However, there are problems such as that the molding cycle is long due to crystallization in the mold, whitening due to crystallization is remarkable, and the heat resistance is remarkably changed depending on the molding conditions. On the other hand, other resins used in food containers include polystyrene,
Polypropylene and the like. However, polystyrene has insufficient heat resistance and low strength,
There is concern about the effects of low molecular weight substances such as monomers and dimers on the environment and the human body. Further, polypropylene has an insufficient heat resistance and an insufficient gas barrier property, so that it is not suitable for long-term storage of foods.

[0003]

SUMMARY OF THE INVENTION Accordingly, the present invention provides good transparency, moldability, sterilization at high temperatures, heat resistance for high-temperature filling of contents and microwave cooking, and stacking when displaying products. It is an object of the present invention to provide a polyester sheet or a molded article having a strength that can withstand the above.

[0004]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a polyester sheet satisfying a specific composition and physical properties, and a polyester molded product obtained by molding the same are obtained as follows. The inventors have found that the above-mentioned problems can be solved, and have reached the present invention. That is, the present invention comprises a dicarboxylic acid component having a terephthalic acid unit as a main component and a glycol component having a tetramethylene glycol unit as a main component, and contains a dicarboxylic acid component other than the terephthalic acid unit with respect to the dicarboxylic acid component. The sum of the amount and the content of the glycol component other than the tetramethylene glycol unit with respect to the glycol component is 3 to 20.
Mol%, the content of the polyether glycol component having 2 or more carbon atoms in the unit monomer relative to the glycol component is 0.5 to 6 mol%, and phenol / 1,1,2,
40 to 99.9% by mass of a polyester resin (A) having an intrinsic viscosity of 0.55 to 1.40 dl / g in a mixed solvent of equivalent amounts of 2-tetrachloroethane at 25 ° C., and a terephthalic acid unit as a main component. A dicarboxylic acid component and a glycol component having an ethylene glycol unit as a main component,
0.55 to 1.40 d intrinsic viscosity at 25 ° C. in a mixed solvent of phenol / 1,1,2,2-tetrachloroethane.
l / g polyester resin (B) 0.1 to 60% by mass
Having an initial haze value of 10% or less at a thickness of 200 μm and a heat treatment at 140 ° C. for 30 minutes relative to the haze value after a heat treatment at 80 ° C. for 30 minutes. The change in the haze value is not more than 20% and the tensile modulus is 700M
Provided is a polyester sheet characterized by being equal to or higher than Pa.

[0005] The present invention also relates to a polyester molded article obtained by molding the polyester sheet, wherein the shrinkage after heat treatment at 80 ° C for 30 minutes is 2% or less, and 14% or less.
Provided is a polyester molded article having a shrinkage of 5% or less after heat treatment at 0 ° C. for 30 minutes. Further, the present invention provides
The present invention provides the above-mentioned polyester molded article, which is a food container usable at a temperature of not more than ° C.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Polyester resin in the present invention
(A) comprises a dicarboxylic acid component and a glycol component. The dicarboxylic acid component has a terephthalic acid unit as a main component. The term "main component" means, for example, that the terephthalic acid unit is 50 mol% or more, preferably 60 mol% or more, more preferably 70 to 1 in the dicarboxylic acid component.
It means that it contains 00 mol%. When the terephthalic acid content is 50 mol% or more, it is preferable in terms of mechanical strength and thermal characteristics. The glycol component of the polyester resin (A) in the present invention has a tetramethylene glycol unit as a main component. The term "main component" means, for example, that tetramethylene glycol is 50 mol% or more, preferably 60 mol% or more, more preferably 70 to 9 mol% in the glycol component.
It means that it contains 9.5 mol%. When the content of tetramethylene glycol is 50 mol% or more, the thermal properties can be maintained.

Examples of the dicarboxylic acid component other than the terephthalic acid unit include aliphatic dicarboxylic acids such as adipic acid and sebacic acid, isophthalic acid, 5-alkylisophthalic acid, 5-sodium sulfoisophthalic acid, and 2,6-naphthalene. Aromatic dicarboxylic acids having two carboxyl groups directly on the benzene ring or naphthalene ring such as dicarboxylic acids, and other p- (β-oxyethoxy) benzoic acids;
4'-dicarboxyphenyl, 4,4'-dicarboxybenzophenone, bis (4-carboxyphenyl) ethane,
And mixtures thereof. Examples of the glycol component other than the tetramethylene glycol unit include alkylene glycols having 2 to 6 carbon atoms such as ethylene glycol, trimethylene glycol, propylene glycol, neopentyl glycol, and hexamethylene glycol, diethylene glycol, triethylene glycol, and 1,4-
Examples thereof include cyclohexanedimethanol, bisphenol A ethylene oxide adduct, and the like, and mixtures thereof.

In the polyester resin (A) of the present invention, the content of a dicarboxylic acid component other than the terephthalic acid unit with respect to the dicarboxylic acid component and the content of a glycol component other than the tetramethylene glycol unit with respect to the glycol component are determined. The total amount (hereinafter referred to as “total modification amount” of the polyester resin (A)) is 3 to 20 mol%, preferably 4 to 15 mol%, more preferably
Preferably, it is 4 to 12 mol%. If it is 3 mol% or more, good workability is exhibited, and if it is 20 mol% or less, it is preferable in terms of good crystallinity, thermal properties, and ease of chip removal after polymerization.

The glycol components other than tetramethylene glycol include polyether glycols having 2 or more carbon atoms in the unit monomer. The polyether glycol includes, for example, polytetramethylene glycol,
Polyethylene glycol, polypropylene glycol,
Or a copolymer of these, and the like, and preferably, polytetramethylene glycol. The mass average molecular weight of the polyether glycol is, for example, 450 to 200.
0, preferably 500-1500. If the mass average molecular weight is 450 or more, the crystallinity of the polyester resin does not become too high, if it is 2000 or less,
It is preferable because the crystallinity of the polyether glycol itself is not increased and the transparency is not impaired. The content of the polyether glycol is 0.5 to 6 mol%, preferably 1 to 4 mol%, more preferably 1 to 3 mol%, based on the glycol component. When it is 0.5 to 6 mol%, good moldability and good heat resistance during molding are exhibited.

The intrinsic viscosity of the polyester resin (A) in the present invention is 0.55 to 1.40 dl / g, preferably
0.7 to 1.2 dl / g, more preferably 0.8 to 1.2 dl / g
A range of 1.2 dl / g is preferred. The intrinsic viscosity is such that the polyester resin (A) of the present invention is
It is a value obtained by dissolving in a solvent obtained by mixing 1,2,2-tetrachloroethane at a mass ratio of 1: 1 and measuring the obtained solution at 25 ° C. using an Ubbelohde viscometer. If the intrinsic viscosity is 0.55 dl / g or more, the polyester resin
It is preferable because the chips after polymerization of (A) can be easily taken out and exhibit good impact resistance, and 1.40 dl /
It is preferable that it is not more than g because good polymerizability is exhibited.

The polyester resin (B) in the present invention comprises:
It consists of a dicarboxylic acid component and a glycol component. The dicarboxylic acid component has a terephthalic acid unit as a main component.
The term "main component" means, for example, that terephthalic acid is 50 mol% or more, preferably 7 mol%, in the dicarboxylic acid component.
0 mol% or more, more preferably 80 mol% or more. When the terephthalic acid content is 50 mol% or more, it is preferable in terms of mechanical strength and thermal characteristics. The glycol component of the polyester resin (B) in the present invention has an ethylene glycol unit as a main component. The term "main component" means, for example, that ethylene glycol is contained in the glycol component in an amount of 50 mol% or more, preferably 70 mol% or more, more preferably 80 mol% or more. When the ethylene glycol content is 50 mol% or more, the thermal properties can be maintained.

Examples of the dicarboxylic acid component other than the terephthalic acid unit include aliphatic dicarboxylic acids such as adipic acid and sebacic acid, isophthalic acid, 5-alkylisophthalic acid, 5-sodium sulfoisophthalic acid, and 2,6-naphthalene. Aromatic dicarboxylic acids having two carboxyl groups directly on the benzene ring or naphthalene ring such as dicarboxylic acids, and other p- (β-oxyethoxy) benzoic acids;
4'-dicarboxyphenyl, 4,4'-dicarboxybenzophenone, bis (4-carboxyphenyl) ethane,
And mixtures thereof. Examples of glycol components other than the ethylene glycol unit include alkylene glycols having 2 to 6 carbon atoms such as trimethylene glycol, propylene glycol, tetramethylene glycol, neopentyl glycol, and hexamethylene glycol, diethylene glycol, triethylene glycol, Examples thereof include 4-cyclohexanedimethanol, bisphenol A ethylene oxide adduct, and the like, and mixtures thereof.

The dicarboxylic acid component other than the terephthalic acid unit and the glycol component other than the ethylene glycol unit include isophthalic acid, diethylene glycol, 1,4-
The component is preferably selected from cyclohexane dimethanol, neopentyl glycol, bisphenol A ethylene oxide 2 adduct, and a mixture thereof. Further, in the polyester resin (B) in the present invention, the content of the dicarboxylic acid component other than the terephthalic acid unit with respect to the dicarboxylic acid component and the total content of the glycol component other than the ethylene glycol unit with respect to the dicarboxylic acid component. The amount is 5-50 mol%,
Preferably, the content is 10 to 25 mol%.

The intrinsic viscosity of the polyester resin (B) in the present invention is 0.55 to 1.40 dl / g, preferably
0.6 to 1.3 dl / g, more preferably 0.7 to 1.3 dl / g
A range of 1.3 dl / g is preferred. The intrinsic viscosity is a value measured by the same method as that for the polyester resin (A). If the intrinsic viscosity is 0.55 dl / g or more,
It is preferable because the chips are easily taken out after the polyester resin (B) is polymerized, and good impact resistance is exhibited, and when it is 1.40 dl / g or less, good polymerizability is exhibited.

The polyester resin composition according to the present invention comprises the polyester resin (A) and the polyester resin
And (B). The content of the polyester (A) is 40 to 99.9% by mass, preferably, to the polyester resin composition of the present invention,
50 to 95% by mass, more preferably 60 to 95% by mass
It is. On the other hand, the content of the polyester resin (B) is
With respect to the polyester resin composition according to the present invention, the amount of 0.1%
It is 1 to 60% by mass, preferably 5 to 50% by mass, more preferably 5 to 40% by mass. Polyester resin
(A) is 40% by mass or less, and a polyester resin
When the content of (B) is 60% by mass or more, the polyester resin composition of the present invention exhibits good heat resistance and is therefore suitable. It is preferable that the content of the polyester resin (A) is 99.9% by mass or less and the content of the polyester resin (B) is 0.1% by mass or more, since good sheet film-forming properties can be obtained.

The polyester resin composition of the present invention may further comprise, if necessary, additives such as an oxidation stabilizer, an ultraviolet absorber, a light stabilizer, an antistatic agent, a lubricant, a fibrous and plate-like inorganic reinforcing agent, and a polycarbonate. , Polymethyl methacrylate, polyolefin resins and the like.

The polyester sheet of the present invention contains a polyester resin layer obtained by forming a film of the polyester resin composition of the present invention by a known method described below. Further, the polyester sheet in the present invention optionally comprises one or more layers of another composition. Here, examples of other compositions include polycarbonate, polymethyl methacrylate, polyolefin, polyester resins other than the polyester resin used in the present invention, and mixtures thereof. The polyester sheet in the present invention,
It may be a single layer or a multilayer, and a resin having improved sealing properties and impact resistance may be used for the surface layer. The film thickness of the polyester sheet in the present invention is not particularly limited, but may be 20 μm to 1 mm, preferably 100 to 8 mm.
It is in the range of 00 μm.

The haze of the polyester sheet thus obtained in the present invention has an initial haze value of 10% or less, preferably 5%, when a polyester sheet having a thickness of 200 μm is measured according to JIS K7105. %, More preferably 3% or less. The change in the haze value after heat treatment at 140 ° C. for 30 minutes with respect to the haze value after heat treatment at 80 ° C. for 30 minutes is preferably 20% or less, preferably 15% or less, and more preferably 10% or less. It is. When the haze value of the initial value is 10% or less, good transparency is exhibited. When the haze change is 20% or less, the haze change is visually small and good transparency is exhibited. is there.

The tensile modulus of the polyester sheet in the present invention is 700 MPa or more, preferably 900 MPa or more, and more preferably 1000 MPa or more when a polyester sheet having a thickness of 200 μm and a width of 10 mm is measured according to JIS K7127. It is. 700
When the pressure is at least MPa, for example, when used as a container, the container has sufficient strength and stiffness to withstand use, and is not deformed due to stacking at the time of product transfer or store display. Further, the polyester molded article of the present invention obtained by molding the polyester sheet of the present invention has a heat shrinkage of 2% or less, preferably 1% or less after heat treatment at 80 ° C for 30 minutes, and at 140 ° C. 30
The heat shrinkage after the partial heat treatment is 5% or less, preferably 2%
% Is preferable. Here, the heat shrinkage rate is
For example, it is measured by a dimensional change or a volume change before and after heat shrinkage of a container-shaped molded article. By having such a heat shrinkage ratio, high-temperature sterilization and high-temperature filling can be performed, and the container can be sufficiently used as a container for microwave cooking.

(Method for Producing Polyester Resin) The polyester resins (A) and (B) used in the present invention are produced by a known polymerization method such as a transesterification method or an esterification method. For example, when the polyester resin (A) is polymerized by a transesterification method, first, a dicarboxylic acid component such as an ester-forming derivative of terephthalic acid and a glycol component such as tetramethylene glycol are mixed at a molar ratio of 1: 2.1 to 2.0. 1:
It is charged into the reaction vessel at a ratio of 2.7, preferably 1: 2.2 to 1: 2.5. Further, as another glycol component, a polyether glycol having 2 or more carbon atoms in the unit monomer is added, and oxidation stability of tetrakis [methylene (3,5-di-t-butyl-4-hydroxyhydrocinnamate)] methane or the like is increased. Add the agent. This is gradually heated to 150 to 220 ° C. over 2 to 5 hours in the presence of a catalyst such as tetrabutoxytitanium to effect a sufficient transesterification reaction. Thereafter, it is -90 kPa or less, preferably -98 to -100.
The polyester resin in the present invention is obtained by heating to 230 to 260 ° C. under a reduced pressure of kPa and performing condensation polymerization for 2 to 5 hours. The unit of Pa used in the present invention is based on the atmospheric pressure where the atmospheric pressure state is 0 Pa except for the value of the tensile modulus.

In the case of the esterification method, a dicarboxylic acid component such as terephthalic acid and a glycol component such as tetramethylene glycol are used in a molar ratio of 1: 1.2 to 1: 2.
2, preferably 1: 1.2 to 1: 1.6 in the reaction vessel. Further, a polyether having 2 or more carbon atoms and tetrakis [methylene (3,5-di-t-butyl-
4-hydroxyhydrocinnamate)] and an oxidation stabilizer such as methane.
The esterification reaction is sufficiently performed by gradually heating to 0 to 220 ° C. over 2 to 5 hours. Then, -90 kPa or less,
Preferably under a reduced pressure of -98 to -100 kPa,
The polyester resin in the present invention is obtained by heating to 260 ° C. and performing condensation polymerization for 2 to 5 hours.

The polyester resin obtained by the above method or the like is discharged into a water tank in the form of a strand, cut into chips by a strand cutter or the like, and dried to remove moisture adhering to the chips. It is used as a resin and as a material of the polyester sheet and the polyester molded product in the present invention. Examples of the catalyst used in the production of the polyester resin in the present invention include zinc acetate, manganese acetate, and magnesium acetate as transesterification catalysts, and antimony trioxide, germanium dioxide, germanium tetrachloride, and dibutyltin oxide as polymerization catalysts. And the like. The catalyst is generally 20 to 20 parts by weight based on the dicarboxylic acid component, depending on the type of the catalyst.
It is added in the range of 1000 ppm.

The polyester sheet in the present invention is produced by any known method such as an extrusion method and a calendering method. For example, in the extrusion method, a dry blend of a polyester resin (A) and a polyester resin (B), or a resin composition obtained by melting and kneading these with an extruder into chips, is then subjected to a gear pump, a T-die, a chill roll, and a winding device. Into an extruder equipped with a polymer and formed under general conditions. Further, the molded article in the present invention can be obtained by molding a polyester sheet by a known method such as vacuum forming, pressure forming and the like.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on embodiments. (Production of polyester resin (A) -1) 95 mol parts of dimethyl terephthalate, 5 mol parts of dimethyl isophthalate, 137.6 mol parts of tetramethylene glycol and 2.4 mol parts of polytetramethylene glycol (Mw = 1000) were purified. It was placed in a reaction vessel equipped with a distillation tower and a stirrer. Further, tetrakis [methylene (3,5-
Di-t-butyl-4-hydroxyhydrocinnamate)] methane was added in an amount of 0.1 mol. After heating the reaction vessel to 140 ° C., tetrabutoxytitanium was added in an amount of 600 ppm (as a 1.5 mass% tetramethylene glycol solution) to the acid component (total of dimethyl terephthalate and dimethyl isophthalate). This is stirred at 220 ° C.
The temperature was gradually increased over 3 hours until the transesterification reaction was performed while distilling off the generated methanol. Then, the product was transferred to a reaction vessel for polycondensation,
Condensation polymerization was carried out at a temperature of 3 ° C. for 3 hours. When a predetermined stirring torque was reached, the stirring was stopped to obtain a polyester resin (A) -1. The obtained polyester resin is discharged into a water tank in the form of a strand, cut into chips by a strand cutter,
Vacuum drying was performed at 120 ° C. for 6 hours to obtain chips.

(Production of polyester resin (A) -2) 90 mol parts of dimethyl terephthalate, 10 mol parts of dimethyl isophthalate and 138.
Polyester except that 8 mol parts, 1.2 mol parts of polytetramethylene glycol and 0.05 mol parts of tetrakis [methylene (3,5-di-t-butyl-4-hydroxyhydrocinnamate)] methane were added. A polyester resin was obtained in the same manner as in the resin (A) -1. (Production of Polyester Resin (A) -3) Except that 70 mol parts of dimethyl terephthalate, 30 mol parts of dimethyl isophthalate and 138.8 mol parts of tetramethylene glycol were added, the same as polyester resin (A) -2 was added. To obtain a polyester resin. (Production of polyester resin (A) -4) 87 mol parts of dimethyl terephthalate, 13 mol parts of dimethyl isophthalate, 131.9 mol parts of tetramethylene glycol, 9.1 mol parts of polytetramethylene glycol and tetrakis [methylene (3,5-di-t-butyl-4-hydroxyhydrocinnamate)] except that 0.3 mole of methane was added.
A polyester resin was obtained in the same manner as the polyester resin (A) -1.

(Production of Polyester Resin (B) -1) 84 mol parts of terephthalic acid, 16 mol parts of isophthalic acid and 150 mol parts of ethylene glycol were put into a reaction vessel equipped with a rectification column and a stirrer. This was gradually heated to 260 ° C. over 3 hours while stirring under a nitrogen atmosphere of 300 kPa, and esterification was performed while distilling off generated water. Thereafter, the product was transferred to a polycondensation reaction vessel, and orthophosphoric acid was added at 30 ppm (as a 10% by mass ethylene glycol solution) to the acid component (total of terephthalic acid and isophthalic acid). Five minutes later, 350 ppm (as a 1.5% by mass ethylene glycol solution) of antimony trioxide as a polymerization catalyst was added to the acid component. Thereafter, the mixture was transferred to a polycondensation reaction vessel and subjected to condensation polymerization at about -99 kPa and 285 ° C. for 3 hours. When a predetermined stirring torque was reached, a polyester resin (B) -1 was obtained. The obtained polyester resin was discharged into a water tank in the form of a strand, cut into chips by a strand cutter, and vacuum-dried at 150 ° C. for 6 hours to form chips.

(Production of Polyester Resin (B) -2) A polyester resin was prepared except that terephthalic acid, 100 mol parts, ethylene glycol 130, and 1,4-cyclohexanedimethanol, 20 mol parts were added without adding isophthalic acid. It carried out similarly to resin (B) -1. (Production of Polyester Resin (B) -3) A polyester resin (B) -1 was used except that 100 mol parts of terephthalic acid, 135 mol parts of ethylene glycol and 15 mol parts of neopentyl glycol were added without adding isophthalic acid. The same was done. (Production of polyester resin (B) -4) Without adding isophthalic acid, 100 mol parts of terephthalic acid, 138 mol parts of ethylene glycol and 12 mol parts of bisphenol A ethylene oxide 2 adduct, and germanium dioxide as a polymerization catalyst were used. 250 ppm based on the acid component (terephthalic acid)
The reaction was carried out in the same manner as for the polyester resin (B) -1, except that the mixture was added (as a 0.45% by mass ethylene glycol solution).

The compositions of the polyester resins (A) and (B) are summarized in Table 1 below. In the table, polyester resin (A) -3 is a reference example because the total modification amount is out of the range of 3 to 20 mol%. Polyester resin (A) -4,
The polyether glycol component having 2 or more carbon atoms (polytetramethylene glycol) in the unit monomer is 0.5 to 6
Since it is out of the range of mol%, it is a reference example. In addition, the content of each component in the table is a value obtained by analyzing each obtained resin by pyrolysis gas chromatography and high performance liquid chromatography.

[Table 1]

(Production of polyester sheet) (Example 1) 60% by mass of polyester resin (A) -1
After dry blending the polyester resin (B) -1 with 40% by mass, an extrusion film forming machine (Thermo Plastics Industry)
(Co., Ltd., 40 mm single screw extruder) to form a film with a resin temperature of 250 ° C. and a chill roll temperature of 5 ° C. and a thickness of 200 μm.
m was obtained. (Example 2) 80 % by mass of a polyester resin (A) -1;
20 mass% of the polyester resin (B) -1 was melt-kneaded at 250 ° C. by a twin-screw extruder (Ikegai Co., Ltd., PCM30) and then pelletized. The pellets were formed into a film with the extrusion film forming machine at a resin temperature of 250 ° C. and a chill roll temperature of 5 ° C. to obtain a polyester sheet having a thickness of 200 μm. (Example 3) 70% by mass of a polyester resin (A) -1;
After dry blending 30% by mass of the polyester resin (B) -2, a film was formed by the extrusion film forming machine so that the resin temperature was 250 ° C. and the chill roll temperature was 5 ° C., and the thickness was 200 μm.
m was obtained.

Example 4 Polyester resin (A) -2 was mixed with 7
After dry blending 0% by mass and 30% by mass of the polyester resin (B) -1, the extruder is used to form a film at a resin temperature of 250 ° C. and a chill roll temperature of 5 ° C. A polyester sheet having a thickness of 200 μm was obtained. (Example 5) 70% by mass of polyester resin (A) -2,
After dry-blending 30% by mass of the polyester resin (B) -3, the resin temperature was 250 ° C.
The film was formed so that the chill roll temperature was 5 ° C, and the thickness was 200
A μm polyester sheet was obtained. (Example 6) 70% by mass of polyester resin (A) -2,
After dry blending the polyester resin (B) -4 with 30% by mass, the resin temperature was 250 ° C.
The film was formed so that the chill roll temperature was 5 ° C, and the thickness was 200
A μm polyester sheet was obtained. (Example 7) PETG # 67 manufactured by Eastman Chemical Company
A polyester sheet obtained by laminating 63 layers and the polyester layer obtained in Example 1 so as to have a thickness ratio of 4: 1 was obtained by using the extrusion film forming machine at a resin temperature of 250 ° C. and a chill roll temperature of 5 ° C. A polyester sheet having a thickness of 200 μm was obtained.

(Comparative Example 1) Polyester resin (A) -1 was mixed with 2
After dry blending 0% by mass and 80% by mass of the polyester resin (B) -1, a film was formed by the extrusion film forming machine so that the resin temperature was 250 ° C. and the chill roll temperature was 5 ° C. A polyester sheet having a thickness of 200 μm was obtained. (Comparative Example 2) 60% by mass of a polyester resin (A) -3;
After dry blending the polyester resin (B) -1 with 40% by mass, the resin temperature was 250 ° C.
The film was formed so that the chill roll temperature was 5 ° C, and the thickness was 200
A μm polyester sheet was obtained. (Comparative Example 3) 70% by mass of polyester resin (A) -4;
After dry blending the polyester resin (B) -1 with 30% by mass, the resin temperature was 250 ° C.
The film was formed so that the chill roll temperature was 5 ° C, and the thickness was 200
A μm polyester sheet was obtained.

(Production of Molded Article) The polyester sheet of each of the above Examples was further molded by a vacuum molding machine at a sheet heating temperature of 75 ° C. and a mold temperature of 140 ° C. A cup-shaped molded product having a length of 40 mm was obtained. Furthermore, although it molded similarly in Comparative Examples 1-3, about Comparative Examples 2-3, a mold was not released,
A good molded product could not be obtained.

The physical properties of the polyester sheet and the molded product obtained in the above Examples and Comparative Examples were measured as follows. -Intrinsic viscosity The intrinsic viscosity is obtained by dissolving a ground product of the polyester resin in a solvent obtained by mixing phenol and 1,1,2,2-tetrachloroethane at a mass ratio of 1: 1. Was measured at 25 ° C. using an Ubbelohde viscometer.・ To measure the transparency of the haze film, the thickness 2
The haze of a polyester sheet of 00 μm is determined according to JIS K
It was measured according to 7105. 23 ° C, 50% relative humidity
After adjusting the temperature and humidity to Rh, the initial value of the haze was measured. Thereafter, the haze value after heat treatment at 80 ° C. for 30 minutes, 140
The haze value after heat treatment at 30 ° C. for 30 minutes was measured, and the haze change was determined as follows. (Haze change (%)) = (Haze value after heat treatment at 80 ° C. for 30 minutes) / (Haze value after heat treatment at 140 ° C. for 30 minutes) × 100 The obtained haze change was evaluated according to the following criteria. ：: Haze change is not more than 20% ×: Haze change exceeds 20% ・ Tensile modulus The tensile modulus of the polyester sheet in the present invention is J
It was measured according to IS K7127. Specifically, 2
Temperature control to 3 ° C, relative humidity 50% Rh, humidity control, film thickness 200
The tensile modulus of a polyester sheet No. 1 test piece having a thickness of 10 μm and a width of 10 mm was measured at 23 ° C. at a test speed of 10 mm per minute. Heat Shrinkage The heat shrinkage of the polyester molded article in the present invention was determined by measuring the volume of the polyester molded article before and after the heat treatment. Specifically, before heat treatment, after heat treatment at 80 ° C. for 30 minutes, and after heat treatment at 140 ° C. for 30 minutes, the three types of cup-shaped polyester molded products were completely filled with water at 23 ° C., and the capacities were measured. did. From the determined values, the heat shrinkage of the polyester molded article after the heat treatment at 80 ° C. and 140 ° C. with respect to the polyester molded article before the heat treatment was determined according to the following equation. (Heat shrinkage (%)) = ((capacity before heat treatment) − (capacity after heat treatment)) / (capacity before heat treatment) × 100

Table 2 below summarizes the physical properties of the polyester sheets and the like obtained in the above Examples and Comparative Examples measured by the above-mentioned measuring methods. Comparative Example 1 is a comparative example because the mass ratio of the polyester resins A and B is less than 40:60, Comparative Example 2 is a comparative example because the haze change is large, and Comparative Example 3 is This is a comparative example because the tensile modulus is low.

Table 2 Physical properties of heat-resistant polyester sheet and its molded product 1 ^{* to} 3 ^* are comparative examples. In the heat shrinkage, "-" indicates that molding is impossible. * 1 Example 7 constitutes two layers of PETG # 6763 layer.

As can be seen from Table 1, the initial haze of each example shows a good value. Therefore, it is understood that the polyester sheet in the present invention has good transparency before the heat treatment. Further, the haze change of each embodiment is also suppressed to a low level. Therefore, it can be seen that the polyester sheet of the present invention can maintain good transparency even after heat treatment, and is excellent in heat resistance. Since the tensile modulus of each example is 700 MPa or more, it is understood that the polyester sheet in the present invention has good tensile strength. Furthermore, the heat shrinkage rate shown in each example is much smaller than that of Comparative Example 1, and it can be seen that the polyester molded article of the present invention has good heat shrink resistance.

[0036]

As described above, the heat-resistant polyester sheet and the molded article of the present invention have good transparency, heat resistance and strength. Therefore, in the field of food containers and the like, high-temperature sterilization and high-temperature filling of the contents become possible, and further, it can be sufficiently used as a microwave cooking container,
A sheet and a container having high heat resistance are provided.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Makoto Tokumizu 4-1-1 Ushikawa-dori, Toyohashi-shi, Aichi F-term (reference) at Mitsubishi Rayon Co., Ltd. Toyohashi Office 3E033 BA17 BB08 CA07 FA04 4F071 AA45 AA46 AH05 BA01 BB01 BB06 BC01 BC08 BC10 BC17 4J002 CF06X CF07W GG01 4J029 AA03 AB07 AC02 AD01 AD10 AE01 AE18 BA02 BA03 BA04 BA05 BA10 BD06A BF09 BF18 BF26 CA02 CA06 CB03A CB05A CB06A CB12A J0301 J0301 J0301 J0301

Claims (3)

[Claims] 1. A dicarboxylic acid component containing a terephthalic acid unit as a main component and a glycol component containing a tetramethylene glycol unit as a main component, and the content of a dicarboxylic acid component other than the terephthalic acid unit with respect to the dicarboxylic acid component. And the content of the glycol component other than the tetramethylene glycol unit with respect to the glycol component is 3 to 20 mol%, and the content of the polyether glycol component having 2 or more carbon atoms in the unit monomer with respect to the glycol component. The amount is 0.5-6 mol%,
0.55 to 1.40 d intrinsic viscosity at 25 ° C. in a mixed solvent of phenol / 1,1,2,2-tetrachloroethane.
l / g of a polyester resin (A) 40 to 99.9% by mass, and a dicarboxylic acid component containing a terephthalic acid unit as a main component,
It comprises a glycol component having an ethylene glycol unit as a main component, and has an intrinsic viscosity of 0.55 at 25 ° C. in a mixed solvent of phenol / 1,1,2,2-tetrachloroethane.
Polyester resin (B) 0.1 to 1.40 dl / g
And an initial haze value at a thickness of 200 μm of 10% or less, and 140 ° C. with respect to the haze value after heat treatment at 80 ° C. for 30 minutes. A polyester sheet, wherein the change in the haze value after heat treatment for 30 minutes is 20% or less and the tensile modulus is 700 MPa or more. 2. A polyester molded article formed by molding the polyester sheet according to claim 1, wherein
Shrinkage after heat treatment for 0 minutes is 2% or less, and
A polyester molded article, wherein shrinkage after heat treatment at 30 ° C. for 30 minutes is 5% or less. 3. The polyester molded article according to claim 2, which is a food container usable at 140 ° C. or lower.