JPH04339824A - Production of polyester - Google Patents

Abstract

PURPOSE:To produce a polyester containing a p-hydroxybenzoic acid component as a comonomer, excelling in thermal properties and shiteness, and having a high degree of polymerization within a short time. CONSTITUTION:A process for producing a polyester by reacting dimethyl terephthalate with ethylene glycol, wherein p-hydroxybenzoic acid is treated with ethylene glycol by heating to 120 deg.C-300 deg.C for 30min or longer and then added to the reaction medium in an arbitrary stage before the completion of the reaction.

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 polyester, and more particularly to a method for producing polyester obtained by copolymerizing an aromatic oxycarboxylic acid component.

0002

BACKGROUND OF THE INVENTION Polyesters, represented by polyethylene terephthalate, have excellent physical and chemical properties and are widely used as fibers, films and other molded products. In order to improve the passability of the process for obtaining these polyester products or to increase the commercial value of polyester products, polyesters are modified by various methods. The method of copolymerizing polyester with a third component is one of the most widely used modification methods.

Copolymerization of an aromatic oxycarboxylic acid component into polyester improves melt spinnability at take-up speeds of 6,000 m/min or more and the mechanical properties of the resulting fibers.
JP-A-59-47423). However, simply adding such an aromatic oxycarboxylic acid component to the polyester manufacturing process slows down the reaction rate and requires a long reaction time to achieve a high degree of polymerization, resulting in a decrease in color tone and poor heat resistance of the resulting polyester. In some cases, polyester with a high degree of polymerization cannot be obtained. Further, when an aromatic oxycarboxylic acid component is added to a polyester reaction system at a high temperature of 200° C. or higher, there is a problem that the reactant foams.

0004

[Problems to be Solved by the Invention] The present inventors have discovered that when aromatic oxycarboxylic acids or their ester-forming derivatives are heat-treated with glycol under specific conditions and then added to the polyester reaction system, the above-mentioned problems can be solved. They found a solution to the problem and completed the present invention.

[0005]

[Means for Solving the Problems] That is, the present invention provides that, in producing a polyester by reacting a dicarboxylic acid and/or an ester-forming derivative thereof with a glycol, at any stage until the reaction is completed, Aromatic oxycarboxylic acid and/or its ester-forming derivative with alkylene glycol at 120°C or more and 300°C or less
This is a method for producing polyester, which is characterized in that the polyester is added to a reaction system after heat treatment for 0 minutes or more.

The polyester of the present invention is produced by reacting a dicarboxylic acid and/or its ester-forming derivative with a glycol. Examples of dicarboxylic acids and/or ester-forming derivatives thereof include aromatic dicarboxylic acids such as terephthalic acid, 2,6-naphthalene dicarboxylic acid, isophthalic acid, and 5-sodium sulfoisophthalic acid, oxalic acid, succinic acid, Examples include aliphatic dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid, eicosanoic acid, and dimer acid, alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, and lower alkyl esters thereof. Although they may be used in combination, it is preferable to use terephthalic acid or dimethyl terephthalate. Specifically, glycols include aliphatic diols such as ethylene glycol, 1,2-propylene glycol, tetramethylene glycol, hexamethylene glycol, and neopentyl glycol, hydroquinone, and bis(4-hydroxy Aromatic diols such as phenyl)sulfone, 2,2-bis(4-hydroxyphenyl)propane, and their ethylene oxide adducts, alicyclic diols such as 1,4-cyclohexanedimethanol, spiroglycol, etc. Examples include polyalkylene glycols such as polyethylene glycol, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol. Although these may be used in combination, it is preferable to use ethylene glycol.

Specifically, the aromatic oxycarboxylic acid and/or its ester-forming derivative added to the reaction system of the polyester of the present invention include paraoxybenzoic acid,
Paraoxymethylbenzoic acid, paraoxyethylbenzoic acid, paraoxypropoxybenzoic acid, paraoxyphenylbenzoic acid, 2-hydroxy-6-carboxynaphthalene, 4'-hydroxybiphenyl-4-carboxylic acid, etc.
and lower alkyl esters thereof, and these may be used in combination, but it is preferable to use paraoxybenzoic acid or methyl paraoxybenzoate. The amount of aromatic oxycarboxylic acid and/or its ester-forming derivative added is not particularly limited, but is from 0.01 to 0.01 to the total dicarboxylic acid components constituting the polyester.
It is preferable to add 30 mol%, and more preferably 0.1 to 20 mol%. If it is less than 0.01 mol%, the modifying effect on the resulting polyester will be insufficient, and if it exceeds 30 mol%, a polyester with a high degree of polymerization will tend not to be obtained.

[0008] Furthermore, the aromatic oxycarboxylic acid and/or its ester-forming derivative in the present invention is heat-treated with glycol at 120°C or more and 300°C or less for 30 minutes or more, and then added to the reaction system. The temperature of heat treatment is 12
If the temperature is less than 0℃, it is not economical because the heat treatment time will be very long to obtain polyester with a high degree of polymerization in a short time, and if it exceeds 300℃, side effects such as etherification of glycol and thermal decomposition may occur during the heat treatment. Since the reaction is accelerated, the heat resistance of the resulting polyester is reduced. Moreover, if the heat treatment time is less than 30 minutes, polyester with a high degree of polymerization cannot be obtained in a short time. The mixing ratio of aromatic oxycarboxylic acid and/or its ester-forming derivative and glycol during heat treatment may be determined as appropriate from the viewpoint of fluidity and economical efficiency of the heat-treated product. It is preferable to add and mix 1.2 to 5 times the molar amount of the oxycarboxylic acid and/or its ester-forming derivative. As the glycol used for the heat treatment, any glycol can be used, or they may be used in combination, but it is preferable to use the same glycol as the glycol constituting the resulting polyester.

The above heat-treated product is added to the reaction system at any stage until the reaction is completed in the polyester manufacturing process. Polyesters, such as polyethylene terephthalate, are usually made into bis(
It is produced by synthesizing 2-hydroxyethyl) terephthalate and its low polymer, and then polycondensing the same at high temperature and under high vacuum until a predetermined degree of polymerization is achieved. In the present invention, the heat-treated product is added at any stage until the reaction is completed.

[0010] The polyester obtained by the method of the present invention can have additives such as matting agents, ultraviolet absorbers, flame retardants, and pigments depending on the purpose, and can also be blended or composited with other polymeric materials. can be used.

In the present invention, it is clear why a polyester with a high degree of polymerization can be obtained without impairing the reactivity of the polyester by heat-treating an aromatic oxycarboxylic acid and/or its ester-forming derivative with glycol. However, it is conceivable that the carboxyl group of the aromatic oxycarboxylic acid component is esterified or transesterified with glycol by the heat treatment, thereby increasing the esterification reactivity of the hydroxyl group of the aromatic oxycarboxylic acid component.

0012

[Examples] The present invention will be specifically explained below using Examples. In addition, each physical property value in an Example was calculated|required by the following method. A. Intrinsic viscosity ([η]) The polymer was dissolved in orthochlorophenol and measured at 25°C. B. Diethylene glycol content ([DEG]) was determined by amine decomposition of the polymer and using gas chromatography. C. It was measured in chip form using a color tone direct reading type color difference meter (Suga Test Instruments Co., Ltd.). The larger the L value, the higher the whiteness, and the larger the b value, the stronger the yellowish tinge. The larger the L value and the lower the b value, the better the color tone.

Example 1 (Heat treatment) A mixture of 6.9 parts by weight of paraoxybenzoic acid and 6.8 parts by weight of ethylene glycol (2.2 times the mole relative to paraoxybenzoic acid) was placed in a reaction vessel equipped with a rectification column. A heat treatment was performed for 4 hours while heating to 200° C. and distilling off by-produced water. (Synthesis of polyester) Dimethyl terephthalate 194
parts by weight, 135 parts by weight of ethylene glycol, and 0.07 parts by weight of manganese acetate as a transesterification reaction catalyst were placed in a transesterification reaction vessel, and gradually heated to allow the reaction temperature to rise while distilling off methanol as a by-product. When the temperature reaches 220°C, add 0.5% trimethyl phosphate as a coloring inhibitor.
Part by weight and 0.6 antimony trioxide as polycondensation catalyst
Parts by weight were added, and ethylene glycol was distilled off until the reaction temperature reached 240°C to complete the transesterification reaction. Next, the obtained transesterification reaction product was transferred to a polycondensation reaction vessel, and the heat-treated paraoxybenzoic acid (
After adding 5.0 mol% based on the total dicarboxylic acid components, the temperature was immediately raised and the pressure was reduced to 0.3 mmHg at 285°C.
．． Polycondensation reaction was carried out for 0 hours to obtain a polymer. The obtained polymer had [η]=0.645 dl/g, [DEG]=0
．． The content was 54% by weight, L=62.5, b=3.0, and the quality was good.

Comparative Example 1 194 parts by weight of dimethyl terephthalate, 135 parts by weight of ethylene glycol, and 0.07 parts by weight of manganese acetate as a transesterification reaction catalyst were placed in a transesterification reaction vessel, and gradually heated. While distilling off the methanol produced, when the reaction temperature reached 220°C, 0.05 parts by weight of trimethyl phosphate as a coloring inhibitor and 0.06 parts by weight of antimony trioxide as a polycondensation catalyst were added, and the reaction temperature was increased. Ethylene glycol was distilled off until the temperature reached 240°C to complete the transesterification reaction. Next, the obtained transesterification reaction product was transferred to a polycondensation reaction vessel, and 6.9 parts by weight of paraoxybenzoic acid (5.0 mol % based on the total dicarboxylic acid components) was added, and the reaction product foamed. It was recognized that there was. Increase temperature and reduce pressure to 0.3mmHg
A polycondensation reaction was carried out at 285° C. for 4.0 hours to obtain a polymer. The obtained polymer had [η]=0.486 dl/g,
[DEG] = 0.87% by weight, L = 51.8, b = 10
．． 9, indicating a low degree of polymerization and a strongly yellowish polymer.

Example 2 194 parts by weight of dimethyl terephthalate, 135 parts by weight of ethylene glycol, 0.07 parts by weight of manganese acetate as a transesterification catalyst, and a mixture obtained by heat treatment in the same manner as in Example 1. Paraoxybenzoic acid (5.0 mol% based on the total dicarboxylic acid components) was placed in a transesterification reaction vessel and gradually heated until the reaction temperature reached 220°C while distilling off the by-produced methanol. Then, 0.05 parts by weight of trimethyl phosphate as a coloring inhibitor and 0.06 parts by weight of antimony trioxide as a polycondensation catalyst were added, and ethylene glycol was distilled off until the reaction temperature reached 240°C to complete the transesterification reaction. did. Next, the obtained transesterification reaction product was transferred to a polycondensation reaction vessel, the temperature was raised and the pressure was reduced, and a polycondensation reaction was carried out at 0.3 mmHg and 285° C. for 4.0 hours to obtain a polymer. The obtained polymer has [η]=0
．． 648dl/g, [DEG]=0.58% by weight, L=
61.0, b=3.9, indicating good quality.

Examples 3 to 6, Comparative Examples 2 to 4 Polymers were obtained in the same manner as in Example 1, except that the heat treatment conditions for paraoxybenzoic acid and ethylene glycol were changed. Table 1 shows the heat treatment conditions and the quality of the obtained polymer. In Examples 3 to 6 in which the heat treatment conditions of the present invention were adopted, polymers with good quality were obtained. However, Comparative Examples 2 to 3 employing conditions different from the heat treatment conditions of the present invention.
4, that is, when the heat treatment temperature was less than 120°C, the [η] of the polymer was low and the yellowish color was strong. When the temperature exceeded 300°C, the [DEG] of the polymer increased. In addition, if the heat treatment time is less than 30 minutes,
Only a polymer with a low [η] and a strong yellow tinge could be obtained.

[0017]

[Table 1]

Examples 7 to 10 Polymers were obtained in the same manner as in Example 1, except that the amount of the heat-treated product of paraoxybenzoic acid and ethylene glycol was changed. Table 2 shows the amount of heat-treated paraoxybenzoic acid added (mol% relative to the total dicarboxylic acids) and the quality of the obtained polymer. Polymers with good quality were obtained in all cases.

[0019]

[Table 2]

Examples 11 to 13 Polymers were obtained in the same manner as in Example 1, except that paraoxybenzoic acid was replaced with another aromatic oxycarboxylic acid. Table 3 shows the added aromatic oxycarboxylic acid species and the quality of the obtained polymer. Polymers with good quality were obtained in all cases.

[0021]

[Table 3]

[0022]

[Effects of the Invention] By employing the method of the present invention, polyester copolymerized with an aromatic oxycarboxylic acid component having a high degree of polymerization and excellent thermal properties and color tone can be obtained in a short time. The value is extremely large.

Claims (1)

[Claims] Claim 1: When producing a polyester by reacting a dicarboxylic acid and/or its ester-forming derivative with a glycol, an aromatic oxycarboxylic acid and/or its ester is added at any stage until the reaction is completed. A method for producing polyester, which comprises heat-treating a formable derivative with glycol at 120° C. to 300° C. for 30 minutes or more, and then adding the derivative to a reaction system.