JPH0790063A - Polyester for molding bottle - Google Patents

Abstract

PURPOSE:To obtain a polyester produced by the solid-phase polymerization of a specific prepolymer containing ethylene terephthalate as main recurring unit, giving decreased amount of white powder depositing on the mold in molding and giving a polyester bottle whose transparency, heat-resistance and mechanical strength are improved. CONSTITUTION:This polyester is produced by using a polyester prepolymer containing ethylene terephthalate as main recurring unit and satisfying the relationship of formula I (Op and Mp are OH terminal group concentration and CH3 terminal group concentration of the prepolymer, respectively; eq/T is concentration unit expressed by equivalent/ton) and performing the solid-phase polymerization of the prepolymer until the obtained polymer satisfies the relationship of formula II (Oc and Mc are OH terminal group concentration and CH3 terminal group concentration of the prepolymer after the solid-phase polymerization, respectively).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester for bottle molding, and more specifically, it has a remarkable effect of reducing white powder which is a problem when it adheres to a mold or the like at the time of molding, and has transparency.
The present invention relates to a polyester capable of forming a bottle having excellent heat resistance and mechanical strength.

[0002]

BACKGROUND OF THE INVENTION Polyesters, especially polyethylene terephthalate, due to their excellent mechanical and chemical properties,
Widely used in textiles, films, industrial resins, bottles, cups, trays, etc. However, in the molding process, various problems occur due to the oligomer present in the polymer or the oligomer formed during molding. Particularly in the bottle molding process, the molding die is contaminated with oligomers, which not only causes the surface of the bottle to deteriorate, but also the transparency, but the oligomer adheres to the vent part, etc. It may not be obtained.

Therefore, in order to solve these problems, a method for reducing the amount of polyester-containing oligomer has been investigated and many proposals have been made. For example, a method of heat-treating polyester in a high vacuum state below its melting point (Japanese Patent Laid-Open Nos. 48-101462 and 51-48).
505), a method of heat-treating polyester at a temperature below its melting point in an inert gas atmosphere (JP-A-55-189331).
No. publication) is proposed. However, when reducing the amount of oligomers by these methods, although it has a white powder reducing effect in a region where the oligomer is relatively high, in a region where the oligomer is low, the white powder reducing effect cannot be sufficiently exerted, and conversely white powder increases. It may happen.

On the other hand, as a method for suppressing the regeneration of the oligomer at the time of molding, a method of partially hydrolyzing polyester with water (JP-A-56-118420) or a water treatment method (JP-A-3-47830) is used. ) Has been proposed, but complicated operations for contacting with water and drying are unavoidable, and it is difficult to avoid an increase in production cost.

[0005]

OBJECT OF THE INVENTION The object of the present invention is to solve the above problems, to significantly reduce white powder that may be a problem when it adheres to a mold during molding, and is excellent in transparency, heat resistance and mechanical strength. The present invention relates to a polyester for molding a bottle, which can be molded and has no increase in cost.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is a polyester whose main repeating unit is ethylene terephthalate, wherein a prepolymer in which the sum of the OH terminal group concentration and the CH ₃ terminal group concentration satisfies the following formula (1) is used. The polyester for bottle molding is obtained by solid-phase polymerization until the sum of the concentrations satisfies the following formula (2).

[0007]

[Equation 2]

Here, the term "mainly" means an amount exceeding 85 mol%. Therefore, in the range of less than 15 mol%, ester units other than terephthalic acid and ethylene glycol can be contained, and such copolymerization components include terephthalic acid, dicarboxylic acids other than ethylene glycol, and diols or oxyacids. Specifically, aromatic dicarboxylic acids such as isophthalic acid, naphthalene dicarboxylic acid, diphenyl dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid,
Diphenyl ketone dicarboxylic acid, sodium sulfoisophthalic acid, dibromoterephthalic acid and the like; alicyclic dicarboxylic acid such as decalin dicarboxylic acid, hexahydroterephthalic acid and the like; aliphatic dicarboxylic acid such as malonic acid,
Succinic acid, adipic acid, etc. are excited. Examples of the glycol component include aliphatic diols such as diethylene glycol, trimethylene glycol, tetramethylene glycol and hexamethylene glycol; aromatic diols such as hydroquinone, catechol, naphthalene diol, resorcin, 4,4′-dihydroxy-diphenyl-sulfone. , Bisphenol A [2,2'-bis (4-hydroxyphenyl) propane], tetrabromobisphenol A, bishydroxyethoxybisphenol A, etc .; alicyclic diols such as cyclohexanediol; aliphatic oxycarboxylic acids such as glycolic acid , Hydroacrylic acid, 3-oxypropionic acid, etc .; alicyclic oxycarboxylic acids such as asiatic acid, quinobaic acid, etc .; aromatic oxycarboxylic acids such as salicylic acid, m- Carboxymethyl benzoic acid, p- hydroxybenzoic acid, mandelic acid, and the like atrolactic acid.

Further, within the range where the polyester is substantially linear, a polyfunctional compound having a valence of 3 or more, such as glycerin,
Trimethylolpropane, pentaerythritol, trimellitic acid, trimesic acid, promellitic acid, tricarballylic acid, gallic acid and the like may be copolymerized, and if necessary, monofunctional compounds such as o-benzoylbenzoic acid and naphthoic acid. May be added.

In the bottle-forming polyester of the present invention, the sum of the concentration of hydroxy end groups and the concentration of methyl end groups of the prepolymer before being subjected to solid phase polymerization is 105 to 115 eq / T.
It is necessary to be. If less than 105 eq / T,
In the subsequent solid phase polymerization, the oligomers that cause white powder cannot be reduced sufficiently.

On the other hand, when it exceeds 115 eq / T, the solid-phase polymerization reaction rate decreases, which leads to a decrease in productivity, and the concentration of hydroxy end groups in the polymer after solid-state polymerization is high, and the oligomer is regenerated during molding. Becomes difficult to suppress.

When a prepolymer satisfying the above conditions is produced by the melt polycondensation method, the polycondensation reaction is carried out at a low temperature of about 260 ° C., and at the same time, the thermal decomposition becomes remarkable as the viscosity increases, and further, the carboxy terminal ends. A method of terminating the reaction at a low degree of polymerization can be exemplified for the purpose of suppressing an increase in the group concentration.

Further, it is essential that the polyester of the present invention has a total of the hydroxy end group concentration and the methyl end group concentration of the polymer after the solid phase polymerization is 68 eq / T or less.

If it exceeds 68 eq / T, the effect of suppressing the oligomer regenerated during molding is insufficient, and the generation of white powder adhering to the mold cannot be suppressed.

In order to produce a polymer satisfying the production conditions for the polyester of the present invention, it is important to consider the concentration of hydroxy end groups in the prepolymer and set the degree of polymerization after the solid phase polymerization reaction to an optimum value. .

For example, the OH end group concentration of the prepolymer and C
215 when the sum of H ₃ terminal group concentration is 108 eq / T
A polyester satisfying the formula (2) of the present invention can be obtained by subjecting the solid-phase polymerization to a reaction temperature of 20 ° C. for about 20 hours and a reaction temperature of 210 ° C. for about 30 hours by a usual method.

It is preferable to use a polymerization catalyst, a stabilizer and the like when producing these polyesters. As these catalysts and stabilizers, those known as catalysts and stabilizers of polyester, particularly polyethylene terephthalate, can be used. Further, if necessary, other additives such as colorants, antioxidants, ultraviolet absorbers, antistatic agents, flame retardants and the like may be used.

[0018]

The bottle-forming polyester of the present invention is remarkably effective in reducing white powder, which is a problem when it adheres to a mold or the like during molding, and can form a bottle excellent in transparency, heat resistance and mechanical strength. .

[0019]

EXAMPLES The present invention will be supplemented by the following examples. In the examples, “parts” means parts by weight, and the methods for measuring the properties used in the examples are shown below. ◆ Concentration of CH ₃ end group Add 10 ml of hydrazine to 20 g of polymer sample and add 1
It was decomposed at 00 ° C. for 40 minutes, and methanol was quantified and converted by glass chromatography. ◆ OH terminal group concentration It was calculated by the following formula.

OH end group concentration = all polymer ends—carboxy end group concentration—CH ₃ end group concentration All polymer end groups: solution measured at 35 ° C. using a mixed solvent of phenol / tetrachloroethane (weight ratio 60/40). The intrinsic viscosity [η] calculated from the viscosity was used and calculated from the following formula.

[0021]

[Equation 3]

Carboxy end group concentration: Determined by neutralization titration by dissolving 0.1 g of a polymer sample in 10 ml of benzyl alcohol at 200 ° C. for 400 seconds. ◆ Amount of oligomer As a representative value, cyclic trimer (hereinafter abbreviated as Cy-3) was quantified. The polymer was dissolved in hexafluoroisopropanol / chloroform (50/50), further diluted with chloroform and filtered through a Millipore filter, and the filtrate was measured by ALC / AGC744 manufactured by Waterf Company. Molding of Proform After drying the polymer at 160 ° C. for 5 hours, 50 g of preform was molded at a cylinder temperature of 295 ° C. using an injection molding machine Dynamelter M-100DM manufactured by Meiki Seisakusho.

[0023]

Example 1 1700 parts of dimethyl terephthalate, 1100 parts of ethylene glycol and 1.5 parts of titanium acetate.
Part (8 ppm as Ti) was charged into a transesterification reaction tank, and transesterification was carried out at 170 to 235 ° C. 0.3 parts of germanium oxide when distillate is no longer produced,
0.4 parts of trimethyl phosphate was added and transferred to a polymerization reaction tank. After 10 minutes of reaction under normal pressure at a reaction temperature of 265 ° C, the reaction is performed under high vacuum (several mmHg or less) for 3.2 hours, and then extracted from the polymerization reaction tank into a large amount of running water by a conventional method to form strand type chips. Got The OH end group concentration of this chip was 96 eq / T, and the CH ₃ end group concentration was 12 eq / T.

After the chips were dried at 160 ° C. for 4 hours, a solid phase polymerization reaction was carried out at 215 ° C. under a high vacuum of 0.5 mmHg for 22 hours. The OH end group concentration of the chip after solid-state polymerization was 53 eq / T, and the CH ₃ end group concentration was 10 eq / T, and the oligomer (Cy-
3) The amount was 0.29 wt%.

When a preform was molded using this chip, the amount of oligomer in the preform was 0.31% by weight.
Met.

[0026]

Example 2 The same method as in Example 1 was used except that the melt polymerization reaction time was 2.8 hours.

[0027]

Comparative Example 1 The same method as in Example 1 was used except that the melt polymerization reaction time was 3.5 hours and the solid phase polymerization reaction temperature was 212 ° C.

[0028]

Comparative Example 2 Melt polymerization reaction was carried out at 265 ° C. for 10 minutes under normal pressure, and then at 270 to 280 ° C. under high vacuum.
The same method as in Example 1 was used except that the reaction was carried out for 2 hours.

[0029]

Comparative Example 3 The same method as in Example 1 was used except that the solid phase polymerization temperature was changed to 209 ° C.

[0030]

Comparative Example 4 The same method as in Example 1 was used except that the melt polymerization reaction was carried out at 260 ° C.

The results of Examples 1 and 2 and Comparative Examples 1 to 4 are shown in Table 1.

[0032]

[Table 1]

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Claims (1)

[Claims] 1. A polyester having ethylene terephthalate as a main repeating unit, the OH end group concentration and C
A polyester for bottle molding, which is obtained by solid-phase polymerizing a prepolymer whose sum with the H ₃ terminal group concentration satisfies the following formula (1) until the sum of both terminal group concentrations satisfies the following formula (2). [Equation 1] [Where Op and Mp are the OH terminal group and CH ₃ terminal group concentration (equivalent / ton; eq / eq) of the prepolymer, respectively.
T), and Oc and Mc respectively represent the OH terminal group and CH ₃ terminal group concentrations of the polymer after solid phase polymerization. ]