JPH08113634A - Production of thermoplastic polyester resin - Google Patents

Abstract

PURPOSE: To produce a thermoplastic polyester resin which can give a lowly crystalline highly transparent molding by using an inexpensive antimony compound as a component of the catalyst. CONSTITUTION: An antimony compound is mixed and reacted with at least one compound selected from the group consitiong of aliphatic α.β-dicarboxylic acids represented by formulas I to IV (wherein R1 , R2 , R3 and R4 are each hydrogen, hydroxy, an alkyl, cycloalkyl, aryl, aralkyl, allyl or an alkoxy; and (n) is an integer of 1 or greater), and the polycondensation is performed in the presence of the obtained reaction product.

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 method for producing a thermoplastic polyester resin used for a sheet or a film. More specifically, it relates to a method for producing a plastic polyester resin which is polycondensed with an antimony compound as a catalyst and has low crystallinity.

[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. Also, a film is produced by 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. Occurs and the transparency is impaired.

Germanium compounds, antimony compounds and titanium compounds are generally used as polycondensation catalysts in the production of polyesters. Of these, germanium compounds are mainly used in fields such as beverage bottles where transparency is required, because polyesters having low crystallinity and a good color tone are easily obtained. However, the price of the germanium compound is about 100 times higher than that of the antimony compound, so that the cost is higher than that in the case of polycondensing polyester with the antimony compound as a catalyst.

When polyester is produced by using an antimony compound as a catalyst, reduced antimony metal is precipitated in the polymer, and the crystallinity becomes high due to the influence of the reduced antimony metal. As a specific phenomenon that the crystallinity becomes high, there is a low temperature rising crystallization temperature (Tc) and a high temperature falling crystallization temperature (Tc ′) as measured by a differential scanning calorimeter (DSC). For this reason,
Crystallization of the resin is likely to occur when the polyester is melted and molded, and then rapidly cooled, or when the molded product thus obtained is reheated. Therefore, in bottle molding that requires a step of molding a thick hollow molded body preform, and further heating and blow molding the preform,
Since it is easy to whiten and it is difficult to obtain a highly transparent bottle,
At present, polyesters using antimony compounds as catalysts are rarely used.

As means for solving these problems, for example, a combination of a germanium compound and an antimony compound as disclosed in JP-A-58-47023, or Japanese Patent Publication No.
As disclosed in Japanese Patent Publication No. 57692, a method of improving transparency by adding a magnesium compound has been proposed. However, the combined use of a germanium compound and an antimony compound has little effect of cost reduction, and addition of a magnesium compound not only has a small effect of decreasing crystallinity, but also advances the field of polymers during polymerization,
The resin produced by these methods is not sufficient for food containers such as beverage bottles, sheets, and films because acetaldehyde, which causes taste and smell, increases.

[0008]

Therefore, the object of the present invention is to provide a method using an antimony compound, which is cheaper than a germanium compound, and has a low crystallinity and a high transparency. The present invention relates to a method for producing a thermoplastic polyester resin that can be used.

[0009]

The above-mentioned objects of the present invention include an antimony compound and a general formula

[Chemical 9]

[Chemical 10]

[Chemical 11]

[Chemical 12] (However, R ₁ , R ₂ , R _3, and R ₄ represent hydrogen, a hydroxyl group, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, an allyl group, or an alkoxy group, and n represents an integer of 1 or more.) And a compound of at least one selected from the group of aliphatic α / β-dicarboxylic acids represented by It

The polyester produced in the present invention is produced by a polycondensation reaction of dicarboxylic acid or its ester-forming derivative with alkylene glycol.
As dicarboxylic acid, terephthalic acid, 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, and terephthalic acid is particularly preferable. Examples of the alkylene glycol include ethylene glycol, butanediol, trimethylene glycol, tetramethylene glycol, neopentyl glycol, 1,4-cyclohexanedimethanol, 2,2-bis (4-β-hydroxyethoxydiphenyl) propane, Examples thereof include bis (4-β-hydroxyethoxydiphenyl) sulfone, and ethylene glycol is particularly preferable.

Examples of the antimony compound used as the polycondensation catalyst include known antimony compounds such as antimony trioxide, antimony acetate, antimony pentoxide, antimony ethoxide and antimony glycoloxide. Among them, antimony trioxide and antimony acetate are preferred. Is particularly preferred because it is widely used as a polymerization catalyst for polyester resins for food containers.

Further, in the present invention, the aliphatic α / β-dicarboxylic acid to be mixed and reacted with the antimony compound is succinic acid, methylsuccinic acid, 2,2-dimethylsuccinic acid, 2,3-dimethylsuccinic acid, ethylsuccinic acid. ,
2,2-diethylsuccinic acid, 2,3-diethylsuccinic acid, 2-methyl-3-ethylsuccinic acid, ethoxysuccinic acid, 2-phenylsuccinic acid, 2-cyclopropenylsuccinic acid, itaconic acid, tartaric acid and the like. . In this,
Since succinic acid, itaconic acid and tartaric acid are recognized as food additives, they are particularly preferable as additives for polyester resins for food containers.

The addition amount of the antimony compound in the present invention is usually 0.01% to 0.03% as antimony atom based on the polyester polymer finally obtained.

In the present invention, the amount of the aliphatic .alpha..beta.-dicarboxylic acid mixed and reacted with the antimony compound is 0.1 with respect to the number of moles of the antimony atom contained in the antimony compound used as the polycondensation catalyst. The amount is preferably 2 to 2 times, more preferably 0.5 to 1.2.
It is twice the mole. When the addition amount of the aliphatic α / β-dicarboxylic acid added to the reaction system is less than 0.1 times the molar amount, the effect of lowering the crystallinity of the polyester is small, and when it exceeds 2 times the molar tone of the polyester is deteriorated. To do.

The antimony compound and the aliphatic .alpha..beta.-dicarboxylic acid may be mixed and reacted by dissolving the antimony compound and the aliphatic .alpha..beta.-dicarboxylic acid in appropriate solvents and then thoroughly mixing them to obtain a homogeneous mixture. There is a method of forming a transparent solution, or a method of adding the other compound to a solution of one of the compounds and thoroughly mixing it to form a uniform and transparent solution. A particularly important point is that the antimony compound and the aliphatic α / β-dicarboxylic acid are sufficiently dissolved to form a transparent solution. If either one remains unmelted, the effect of lowering the crystallinity of the polymer is not sufficiently exerted. Although the reaction product of the antimony compound and the aliphatic α / β-dicarboxylic acid has not been sufficiently clarified, a complex compound in which the aliphatic α / β-dicarboxylic acid is coordinate-bonded to the antimony atom in the antimony compound. It is estimated to be.

The catalyst thus obtained (mixing of antimony compound and aliphatic α / β-dicarboxylic acid, reaction product) is usually added after transesterification or esterification reaction or during polycondensation. It may be added before that.

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.

[0018]

According to the production method of the present invention, a polyester having low crystallinity can be produced by using an antimony compound which is cheaper than a germanium compound. Therefore, it is possible to inexpensively obtain a polyester suitable as a container such as a beverage bottle that requires transparency.

[0019]

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 It is a value measured at 20 ° C in a mixed solvent of phenol and 1,1,2,2-tetrachloroethane of 6: 4 (weight ratio). -Crystallinity evaluation Approximately 10 mg of sample was used as DSC
After melting in C-7) at 300 ° C for 5 minutes, 3
The temperature of the exothermic peak of crystallization, which was obtained when the temperature was rapidly cooled to 0 ° C. at 00 ° C./minute and then increased at 10 ° C./minute, was defined as the temperature-rising crystallization temperature (Tc). The temperature of the exothermic peak of crystallization obtained when the temperature was raised to 300 ° C., melting was performed for 5 minutes, and the temperature was lowered at 10 ° C./minute was set as the temperature-falling crystallization temperature (Tc ′). In general, it can be determined that the higher the temperature rising crystallization temperature is, the lower the temperature falling crystallization temperature is, the lower the crystallinity is, and the easier it is to give a molded article having good transparency.

Example 1 2 parts by weight of antimony trioxide were added to ethylene glycol 96.
To a solution dissolved in 2 parts by weight, 1.8 parts by weight of itaconic acid were mixed and reacted 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 put into a polymerization vessel having a rectification column, and then heated to 250 ° C. with stirring while flowing a slight amount of nitrogen. During this time, ethylene glycol was refluxed and only water was distilled out of the system. When the transesterification rate reached 80% as calculated from the amount of distilled water, 3.9 parts by weight of the catalyst solution and 1.3 parts by weight of a solution containing 5% by weight ethylene glycol of trimethyl phosphate were added. Next, while continuing heating and stirring, the pressure was gradually reduced, 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. Polymerization was continued in this state until a predetermined stirring torque (torque at which the intrinsic viscosity of the polymer was around 0.6) was reached. After that, return to normal pressure,
The content was extruded in a gut shape, cooled with water, and then a pelletized polymer was obtained using a cutter. The intrinsic viscosity of this polymer was 0.66 (dl / g), the temperature rising crystallization temperature Tc was 148.4 ° C., and the temperature falling crystallization temperature Tc ′ was 187.5 ° C.

Comparative Example 1 A polymer was polymerized in the same manner as in Example 1 except that an aliphatic α / β-dicarboxylic acid was not mixed and reacted and a catalyst solution containing 98 parts by weight of ethylene glycol was used.
Table 1 shows the intrinsic viscosity and crystallization temperature of the obtained polymer.

Example 2 Example 2 was repeated except that 2.1 parts by weight of tartaric acid were mixed and reacted in place of 1.8 parts by weight of itaconic acid and a catalyst solution containing 95.9 parts by weight of ethylene glycol was used. The polymer was polymerized as in 1. Table 1 shows the intrinsic viscosity and crystallization temperature of the obtained polymer.

Example 3 Example 1 was repeated except that 1.6 parts by weight of succinic acid was mixed and reacted in place of 1.8 parts by weight of itaconic acid, and a catalyst solution containing 96.4 parts by weight of ethylene glycol was used. The polymer was polymerized as in Example 1. Table 1 shows the intrinsic viscosity and crystallization temperature of the obtained polymer.

Example 4 A polymer was prepared in the same manner as in Example 1 except that the mixed and reacted itaconic acid was changed from 1.8 parts by weight to 4 parts by weight and a catalyst solution containing 94 parts by weight of ethylene glycol was used. Was polymerized. The obtained polymer was slightly yellowish. It was not suitable as a resin for bottles. The intrinsic viscosity and crystallization temperature of this polymer are shown in Table 1.

Comparative Example 2 A catalyst solution was prepared by dissolving 2 parts by weight of antimony trioxide in 98 parts by weight of ethylene glycol. Next, 254 parts by weight of bis (β-hydroxyethyl) terephthalate and 83 parts by weight of terephthalic acid were put into a polymerization vessel having a rectification column, and then heated to 250 ° C. with stirring while flowing a slight amount of nitrogen. During this time, ethylene glycol was refluxed and only water was distilled out of the system. When the transesterification rate reached 80% as calculated from the amount of distilled water, the catalyst solution 3.9
Parts by weight and 0.07 parts by weight of itaconic acid were added separately. Furthermore, 1.3 parts by weight of a 5% by weight ethylene glycol solution of trimethyl phosphate was added. Then, polymerization was performed in the same manner as in Example 1 to obtain a polymer in pellet form. The intrinsic viscosity of this polymer was 0.63 (dl / g), the temperature rising crystallization temperature Tc was 143.0 ° C., and the temperature falling crystallization temperature Tc ′ was 20.
It was 3.0 ° C., and the crystallinity was the same as that when itaconic acid was not added.

[0027]

[Table 1]

Claims (2)

[Claims] 1. An antimony compound and a compound of the general formula: Embedded image Embedded image [Chemical 4] (However, R ₁ , R ₂ , R _3, and R ₄ represent hydrogen, a hydroxyl group, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, an allyl group, or an alkoxy group, and n represents an integer of 1 or more.) A method for producing a thermoplastic polyester resin, which comprises mixing and reacting at least one compound selected from the group of aliphatic α / β-dicarboxylic acids represented by the formula (9), and subjecting the mixture to polycondensation using the compound as a catalyst. 2. A mixture and reaction with an antimony compound,
General formula: [Chemical 6] [Chemical 7] Embedded image (However, R ₁ , R ₂ , R _3, and R ₄ represent hydrogen, a hydroxyl group, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, an allyl group, or an alkoxy group, and n represents an integer of 1 or more.) The at least one compound selected from the group of aliphatic α / β-dicarboxylic acids represented by is 0.1 to 2 times the mole of the antimony atom contained in the antimony compound. The method for producing a thermoplastic polyester resin.