JPH08157581A - Thermoplastic polyester resin - Google Patents

Abstract

PURPOSE: To obtain a thermoplastic polyester resin which is produced without using the third component as a comonomer and gives a molding which does not whiten even when.heated to a high temp. by forming a polyester resin from specific components and specifying the intrinsic viscosity and density. CONSTITUTION: This polyester resin mainly comprises polyethylene terephthalate, has an intrinsic viscosity [η] of 0. 70-0.90dl/g when measured at 20 deg.C in a mixed solvent comprising phenol and 1,1,2,2-tetrachloroethane in a wt. ratio of 6:4, has such properties that, when the resin is molded into an amorphous molding having an intrinsic viscosity [η] of 0.65-0.90-dl/g and a density at 23 deg.C of 1.3337g/cm<3> or lower and heated at 140 deg.C for 3min, the density of the molding becomes 1.336g/cm<3> or lower, and is produced by using a catalyst comprising a mixture of a germanium compd. with a tetraalkylammonium hydroxide represented by the formula (wherein R1 , R2 , R3 , and R4 are each alkyl).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to containers such as beverage bottles,
The present invention relates to a thermoplastic polyester resin used for a sheet or a film. More specifically, the present invention relates to a thermoplastic polyester resin that is unlikely to be whitened during stretch molding such as blow molding.

[0002]

2. Description of the Related Art Polyester represented by polyethylene terephthalate is widely used for fibers, films and the like because of its excellent mechanical properties, chemical properties and transparency. In recent years, in particular, its use in beverage bottles and food containers is rapidly spreading.

Generally, hollow containers such as bottles are manufactured by supplying a thermoplastic polyester resin to a molding machine such as an injection molding machine to mold a preform for a hollow molded body, and heating the preform to blow-mold it. To be done. A container such as a tray is manufactured by supplying a thermoplastic polyester resin to an extruder, extruding it from a T die to prepare a sheet, and thermoforming this sheet. A film is produced by uniaxially or biaxially stretching this sheet.

A problem in producing these containers and films is that the resin is crystallized when the thermoplastic polyester resin is melted and molded and then rapidly cooled, or when the molded product thus obtained is reheated. Is caused by bleaching.

In particular, when manufacturing a container such as a soft drink bottle which is required to have heat resistance, it is necessary to heat the preform for a hollow molded article to a high temperature to perform stretching in order to remove residual strain due to stretching. is there. Therefore, when heating the preform or sheet for a hollow molded body, whitening due to crystallization of the resin becomes a serious problem. In recent years, as the demand for heat resistance of containers has increased, and as the production rate of containers has increased, it has been desired to carry out stretch molding at a higher temperature, and therefore whitening does not occur even when heated to a high temperature. There is a need for a thermoplastic polyester resin that is a molded body.

As a thermoplastic polyester resin which does not whiten even when heated to a high temperature, there may be mentioned a copolymer of a third component. When this is used, the oriented crystallinity at the time of stretching is lowered. However, there is a problem that the heat resistance and mechanical strength of the obtained container are unavoidably reduced.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermoplastic polyester in which a third component is not copolymerized and which becomes a molded product which does not whiten even when heated to a high temperature. Is.

[0008]

The above-mentioned object of the present invention is a polyester resin containing polyethylene terephthalate as a main constituent, which comprises phenol, 1,1,
The intrinsic viscosity [η] measured at 20 ° C. in a mixed solvent of 2,2-tetrachloroethane 6: 4 (weight ratio) is 0.70 to
It is in the range of 0.90 dL / g, the resin has an intrinsic viscosity [η] of 0.65 to 0.90 dL / g, and an amorphous molding so that the density measured at 23 ° C. is 1.337 g / cm ³ or less. This is achieved by a thermoplastic polyester resin characterized by having a density of 1.366 g / cm ³ or less when a molded body is molded and the amorphous molded body is heated at 140 ° C. for 3 minutes.
Further, this thermoplastic polyester resin is specifically composed of a germanium compound and a general formula

Embedded image (Wherein R ₁ , R ₂ , R ₃ , and R ₄ are the same or different alkyl groups), at least one compound is mixed, and polycondensation is performed using this as a catalyst. Obtained by

The polyethylene terephthalate forming the skeleton in the present invention has ethylene terephthalate as a main repeating unit, which is produced by carrying out melt polymerization and subsequent solid phase polymerization according to a conventionally known method. It is also possible to replace a part of the glycol component and / or the dicarboxylic acid component with another glycol or dicarboxylic acid as long as the oriented crystallinity of the resin is not deteriorated. For example, diethylene glycol, butanediol, trimethylene glycol, tetramethylene glycol, neopentyl glycol, 1,4-cyclohexanedimethanol, 2,2-bis (4-β-hydroxyethoxydiphenyl) propane, bis (4-β-
Hydroxyethoxyphenyl) sulfone, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid,
4,4'-diphenyldicarboxylic acid, adipic acid, azelaic acid, sebacic acid and the like can be mentioned.

The intrinsic viscosity [η] of this resin is 6: 6 for phenol and 1,1,2,2-tetrachloroethane.
The value measured at 20 ° C. in a mixed solvent of 4 (weight ratio) is in the range of 0.70 to 0.90 dL / g. If the intrinsic viscosity [η] is less than 0.70 dL / g, the mechanical strength of the molded product will be low, and if it exceeds 0.90 dL / g, the residual strain during stretching will be large and the heat resistance will be reduced.

As a method for producing a molded product from this resin, the molded product has an intrinsic viscosity [η] of 0.65 to 0.90 dL /
Any known method may be used as long as it is an amorphous molded body having a density of 1.337 g / cm ³ or less at 23 ° C. Specifically, there are a method by injection molding, a method in which a resin is supplied to an extruder and extruded from a T die, and the like.

The amorphous compact thus obtained was heated to 140 ° C.
As the method for heating for 3 minutes in the above, any known method may be used as long as the molded body is heated uniformly, and for example, there is a method of putting it in an oil bath at 140 ° C. for 3 minutes.

The density of the molded body after heating is 1.36.
It should be 6 g / cm ³ or less. 1.366g
If it exceeds / cm ³ , whitening occurs during stretch molding such as blow molding.

As the germanium compound serving as a catalyst for the thermoplastic polyester resin, germanium dioxide,
Germanium tetraethoxide, germanium tetra-
Known germanium compounds such as n-butoxide may be mentioned. Among them, germanium dioxide is used as a polymerization catalyst for polyester resin for food containers,
Particularly preferred.

Further, in the present invention, the tetraalkylammonium hydroxide mixed with the germanium compound is tetramethylammonium hydroxide,
Examples thereof include tetraethylammonium hydroxide, tetrabutylammonium hydroxide, trimethylethylammonium hydroxide, triethylmethylammonium hydroxide, triethylbutylammonium hydroxide, tributylethylammonium hydroxide.

The addition amount of the germanium compound in the present invention is a known addition amount (0.005 to germanium atom based on the polyester polymer finally obtained).
0.02%).

In the present invention, the amount of tetraalkylammonium hydroxide mixed with the germanium compound is 0. 0 with respect to the number of moles of germanium atoms contained in the germanium compound used as the polycondensation catalyst.
It is 1 to 2 times mol, preferably 0.3 to 1.5 times mol. When the amount of tetraalkylammonium hydroxide to be mixed is less than 0.1 times the molar amount, the intrinsic viscosity [η] molded from this resin is 0.65 to 0.90 dL /
g, an amorphous compact having a density of 1.337 g / cm ³ or less measured at 23 ° C. also has a density of 1. after heating at 140 ° C. for 3 minutes.
It does not fall below 366 g / cm ^3, and whitening occurs during stretch molding such as blow molding. On the other hand, if the amount exceeds 2 times, the color tone of the polymer deteriorates.

As a method for mixing the germanium compound and the tetraalkylammonium hydroxide, a method of dissolving the germanium compound and the tetraalkylammonium hydroxide in an appropriate solvent and then thoroughly mixing them to obtain a uniform and transparent solution, Alternatively, there is a method of adding the other compound to a solution of one of the compounds and thoroughly mixing them to obtain a uniform and transparent solution. A particularly important point is that the germanium compound and the tetraalkylammonium hydroxide are sufficiently mixed to form a transparent solution. When either one remains unmelted, the intrinsic viscosity [η] molded from the resin polymerized using this is 0.65 to 0.90 dL / g, and the density measured at 23 ° C. is 1.337 g / cm ³ or less. Amorphous compact of 140
The density after heating at 3 ° C. for 3 minutes does not fall below 1.366 g / cm ^3, and whitening occurs during stretch molding such as blow molding. Generally, a germanium compound is used as an aqueous solution.However, when a tetraalkylammonium hydroxide is dissolved in water in advance at the time of preparing the aqueous solution, the germanium compound is added, compared with the case where the tetraalkylammonium hydroxide is not dissolved in water, it is extremely The germanium compound dissolves easily. From this, the tetraalkylammonium hydroxide reacts with the germanium compound that is the catalyst to convert the germanium compound into a compound that is easily dispersed or dissolved in the polymer, and therefore the crystallinity of the polymer decreases, that is, It is presumed that whitening during stretch molding can be suppressed.

The catalyst thus obtained (mixture of germanium compound and tetraalkylammonium hydroxide) is preferably added after the usual transesterification or esterification reaction, or during polycondensation, but before that. Can be added to.

Further, in the present invention, a known stabilizer such as a phosphorus compound may coexist. Further, it may be used in combination with a pigment such as titanium oxide or an antistatic agent.

[0021]

The thermoplastic polyester resin of the present invention is
Compared with conventional polyester resins, it becomes a molded body that does not whiten even when heated to a high temperature, and since orientation crystallinity does not decrease during stretching, high heat resistance, a container such as a bottle having mechanical strength can be easily and It can be produced efficiently.

[0022]

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

Various measuring methods used in the present invention are shown below. (Resin intrinsic viscosity) 20 ° C. in a mixed solvent of phenol and 1,1,2,2-tetrachloroethane 6: 4 (weight ratio)
It is the value measured in. (Density) It is a value measured at 23 ° C. by producing a density gradient tube using carbon tetrachloride and n-heptane as a dipping solution by a method according to JIS K7112 D method.

Example 1 2.3 parts by weight of tetraethylammonium hydroxide and 2.6 parts by weight of germanium dioxide were mixed and purified water 9
It was dissolved in 5.1 parts by weight to prepare a transparent catalyst solution. Next, 254 parts by weight of bis (β-hydroxyethyl) terephthalate and 83 parts by weight of terephthalic acid were charged into a polymerization vessel having a rectification column, and then 250 ° C. while flowing a slight amount of nitrogen.
Heated with stirring. During this time, only water was distilled out of the system. Calculated from the amount of distilled water, when the transesterification rate reached 80%, 3 parts by weight of the catalyst solution and a 5% by weight ethyleglycol solution of trimethylphosphoric acid 1.
3 parts by weight was added. Then, the pressure was gradually reduced while continuing heating and stirring, and the inside of the can was set to a high vacuum of 5 torr or less over about 1 hour. During this time, the temperature was raised to 285 ° C. In this state, the polymerization was continued until a predetermined stirring torque (torque at which the intrinsic viscosity of the polymer became around 0.5 dL / g) was reached. Then, the pressure was returned to normal pressure, the content was extruded into a gut shape, and after cooling with water, a polymer in pellet form was obtained using a cutter. Reduce the pressure of this polymer below 1 torr,
Solid phase polymerization was carried out at 215 ° C. for 19 hours to obtain a polymer having an intrinsic viscosity [η] of 0.74 dL / g.

Next, an amorphous molded product (length 90 mm, width 50 mm, thickness 2 mm) is injection-molded using this polymer.
Was produced. The intrinsic viscosity [η] of this amorphous molded product is 0.7.
The density was 0 dL / g and the density was 1.336 g / cm ³ . Part of this amorphous molded product (length 4 mm, width 4 mm, thickness 4 m
m) was cut out and placed in an oil bath at 140 ° C. for 3 minutes to have a density of 1.360 g / cm ³ .

From this polymer by injection molding 1.5
A preform for a liter bottle was produced. Then, preheating time is 68 seconds as preform heating conditions, surface temperature of preform after preheating is 95 to 97 ° C., and blow molding is performed using a stretch blow molding machine in which blow pressure is set to 25 Kg / cm ² as blow conditions. , Average body thickness 300μ
A bottle having a volume of 1.5 m and an internal volume of 1.5 liter was obtained. The transparency of this bottle was good.

Comparative Example 1 Tetraethylammonium hydryloxide was not added,
2.6 parts by weight of germanium dioxide was dissolved in 97.4 parts by weight of purified water to prepare a transparent catalyst solution, and the polymer was polymerized in the same manner as in Example 1 except that it was used as a catalyst. The intrinsic viscosity [η] of the obtained polymer was 0.74.
It was dL / g.

An amorphous molded product was produced from this polymer in the same manner as in Example 1. The amorphous molded product has an intrinsic viscosity [η] of 0.69 dL / g and a density of 1.336 g / cm ^3.
Met. Part of this amorphous molded product (length 4 mm, width 4 m
m, thickness 4 mm) was cut out and placed in an oil bath at 140 ° C. for 3 minutes, and the density was 1.370 g / cm ³ .

From this polymer, a bottle having an average wall thickness of 300 μm and an internal volume of 1.5 liter was obtained in the same manner as in Example 1. The transparency of this bottle was poor.

Claims (3)

[Claims] 1. A polyester resin containing polyethylene terephthalate as a main constituent, which is an ultimate limit measured at 20 ° C. in a mixed solvent of phenol and 1,1,2,2-tetrachloroethane at a ratio of 6: 4 (weight ratio). The viscosity [η] is in the range of 0.70 to 0.90 dL / g, and the intrinsic viscosity [η] from this resin is 0.65 to 0.90 dL / g, 23
Amorphous compacts were molded so that the density measured at ℃ was 1.337g / cm ³ or less.
A thermoplastic polyester resin having a density of 1.366 g / cm ³ or less when heated for a minute. 2. A germanium compound and a general formula: (Wherein R ₁ , R ₂ , R ₃ , and R ₄ are the same or different alkyl groups), at least one compound is mixed, and polycondensation is performed using this as a catalyst. A thermoplastic polyester resin according to claim 1. 3. A compound of the general formula: embedded image which is mixed with a germanium compound. The tetraalkylammonium hydroxide compound represented by (R ₁ , R ₂ , R ₃ , and R ₄ are the same or different alkyl groups) is 0.1 to the number of moles of germanium atom contained in the germanium compound. The thermoplastic polyester resin according to claim 1, which has a double mole.