JPS5922729B2 - Polyester manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing polyester, particularly to a method for producing aromatic polyester having good heat resistance and color tone.

Polyester, especially polyester containing polyethylene terephthalate or ethylene terephthalate as a main component, has many excellent properties and is therefore widely used as a material for fibers, films, and other molded products.

Such polyester, particularly polyethylene terephthalate, is produced by heating ethylene glycol ester of terephthalic acid and/or its low polymer under reduced pressure to cause a polycondensation reaction.

This polycondensation reaction can proceed smoothly and produce commercially valuable products only by using a catalyst, and the reaction rate varies depending on the type of polycondensation catalyst used. The quality of the product is greatly affected. Tetraalkyl orthotitanates such as tetrabutyl orthotitanate have been known as having excellent polycondensation catalytic ability.

However, when tetrabutyl orthotitanate is used, the resulting polyester tends to be yellowish, and especially when used in an amount sufficient to achieve industrial production speed, the resulting polyester exhibits a deep yellow color and has poor heat resistance. Getting worse. A method for preventing coloring when using this titanium compound has been proposed. In other words, the special public service of 1972
Japanese Patent Publication No. 2229-2229 discloses a method using titanium hydride, and Japanese Patent Publication No. 47-26597 discloses a method using α-titanic acid. however,
In the former method, it is not easy to powderize titanium hydride, and in the latter method, α-titanic acid is easily deteriorated, and it is not easy to store and handle, so both are not suitable for industrial use. Moreover, these methods cannot improve heat resistance. This deterioration in heat resistance causes deterioration in molding properties, particularly clogging of the spinning pack during melt spinning, yarn breakage during stretching, etc. As a result of intensive research into a polyester polycondensation method using a titanium compound that does not have these drawbacks, the present inventor found that if cobalt acetate and nickel acetate are co-existed with tetrabutyl orthotitanate or this polymer and a polycondensation reaction is carried out. It has been found that polyester with good color tone and good heat resistance can be obtained very easily.

The present invention is based on this knowledge and is the result of further intensive research.
It is completed. That is, the present invention provides glycol esters of at least one difunctional aromatic carboxylic acid and/or
Or, in producing a polyester by subjecting the low polymer to a polycondensation reaction in the presence of a titanium compound represented by the following general formula, the polycondensation reaction is carried out using a cobalt compound and the free acid component 100 of the difunctional aromatic carboxylic acid. 0 per part by weight.
0001 to 0.02 parts by weight of nickel acetate, nickel chloride, or nickel carbonate is used in combination.

General formula [wherein R is a hydrogen atom or a monovalent aliphatic group, and n is an integer of 1 or more].

] The glycol ester of difunctional aromatic carboxylic acid used in the present invention may be produced by any method.

It is usually produced by heating and reacting a difunctional carboxylic acid or its ester-forming derivative with a glycol or its ester-forming derivative. The difunctional aromatic carboxylic acid used here mainly refers to terephthalic acid, and its ester-forming derivatives have 1 to 4 carbon atoms.
Alkyl esters, phenyl esters, and the like are preferably used.

In addition, other difunctional aromatic carboxylic acids such as isophthalic acid, naphthalene dicarboxylic acid, diphenylcarboxylic acid, diphenylmethane dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenoxyethane dicarboxylic acid, β-
It may also be hydroxyethoxybenzoic acid or ester-forming derivatives thereof. In addition, a part of the main difunctional aromatic carboxylic acid component may be replaced with other difunctional aromatic carboxylic acid components and/or difunctional aliphatic carboxylic acids such as sebacic acid, adipic acid, oxalic acid, 1,4- It may be replaced with a difunctional alicyclic carboxylic acid such as cyclohexanedicarboxylic acid or an ester-forming derivative thereof. Glycol mainly refers to ethylene glycol, and as its ester-forming derivative, ethylene oxide is particularly preferably used.

Others such as tetramethylene glycol, trimethylene glycol, cyclohexane-1,4-dimethanol, etc.
It may also be a monomer or alicyclic glycol. A method for producing a glycol ester and/or a low polymer thereof from such an acid component and glycol includes, for example, an ethylene glycol ester of terephthalic acid and/or a low polymer thereof, which are constituent raw materials of polyethylene terephthalate. Generally, a method is employed in which a direct esterification reaction is carried out with ethylene glycol, a transesterification reaction is carried out between a lower alkyl ester of terephthalic acid and ethylene glycol, or a method in which terephthalic acid is subjected to an addition reaction with ethylene oxide. Although any catalyst can be used in these reactions, it is preferable to select and use a catalyst that does not adversely affect the color tone, taking into account the purpose of the present invention. In particular, when adopting the transesterification method, the titanium compound represented by the general formula (1) used as the polycondensation catalyst in the present invention and/or the cobalt compound and/or nickel compound described below may be used as the transesterification catalyst. can be done, and it is also a good thing to do so. In the general formula (1) representing the titanium compound used as a polycondensation catalyst in the present invention, R is a hydrogen atom or a monovalent aliphatic group, and this monovalent aliphatic group has 1 to 8 carbon atoms. An alkyl group is preferred, and an alkyl group having 1 to 5 carbon atoms is particularly preferred.

n is an integer of 1 or more, usually 1 to 50, preferably 1 to 25. Preferred specific examples of such titanium compounds include ornotitanic acid, tetra-n-butylornotitanate, tetrapropylorthotitanate, tetraethylornotitanate, tetramethylornotitanate, and polymers thereof.
There is no need to particularly limit the amount of the titanium compound used, but if it is too small, a sufficient polycondensation reaction rate cannot be obtained, and if it is too large, the resulting polyester tends to turn yellow, so it is usually used as a polyester raw material. 0.001 to 0.1 part by weight, preferably 0.005 parts by weight per 100 parts by weight of the difunctional carboxylic acid component used as a free acid.
~0.07 parts by weight.

The titanium compound may be added at any time before the completion of the polycondensation reaction, but it is preferably added between before and immediately after the start of the polycondensation reaction.

In particular, when the titanium compound is also used as a transesterification catalyst, it is preferable to add the titanium compound in the above amount between before and immediately after the start of the transesterification reaction. When adding,
The titanium compound may be dissolved or added as a slurry in an appropriate amount of glycol. There are no particular restrictions on the cobalt compound used in combination with the titanium compound, but
Divalent cobalt compounds are preferred, and specific examples of such compounds include halides such as cobalt chloride, organic carboxylates such as cobalt acetate and cobalt benzoate, and inorganic compounds such as cobalt nitrate, cobalt carbonate, cobalt phosphate, and cobalt phosphite. Examples include acid salts, among which halides and organic carboxylic acid salts are particularly preferred.

If the amount used is too small, the effect of sufficiently improving the color tone and heat resistance will be small, and if the amount is too large, the color tone and heat resistance of the resulting polymer will tend to worsen. 0.001 to 100 parts by weight of free acid of the carboxylic acid component
0.07 parts by weight is preferred, especially 0.005 to 0.05 parts by weight.
Parts by weight are preferred. The timing of addition is not particularly limited, but
It should be added before the reaction mixture becomes yellowish;
It is preferably added before the viscosity of the reaction mixture increases significantly. It is particularly preferable to add it before the beginning of the polycondensation reaction, and even if it is added after being mixed with the titanium compound in advance,
They may also be added separately. The titanium compound and cobalt compound are nickel acetate, nickel chloride, or nickel carbonate.

Other than such nickel compounds, the effect of improving the hue of the obtained polyester is poor, or the cost is high, which is disadvantageous in terms of operation.

The amount of the nickel compound used is 0.0001 to 0.02 parts by weight, preferably 0.0001 to 0.02 parts by weight, based on 100 parts by weight of the difunctional carboxylic acid component used as the polyester raw material, calculated as free acid.
．． 0005 to 0.01 part by weight is required.

Here, if the amount of the nickel compound used is less than 0.0001 part by weight, the hue improvement effect of the obtained polyester will be small,
If the amount exceeds 0.02 parts by weight, the hue of the polyester becomes black.

In addition, the timing of its addition is similar to the above cobalt compound.
Although not particularly limited, it should be added before the reaction mixture turns yellowish, and it is particularly preferable to add it before the beginning of the polycondensation reaction. It may be added in advance by mixing with the titanium compound and/or cobalt compound, or may be added separately. The polycondensation reaction carried out in the presence of the titanium compound, cobalt compound and nickel compound does not require special conditions, and the glycol ester of difunctional aromatic carboxylic acid and/or its low polymer is subjected to the polycondensation reaction. The conditions employed when producing polyester are optionally adopted.

In the case of polyethylene terephthalate, generally, a nitylene glycol ester of terephthalic acid and/or a low polymer thereof containing the above amounts of a titanium compound, a cobalt compound, and a nickel compound are added and blended under reduced pressure to a temperature of 30°C above its melting point.
A method is employed in which a polycondensation reaction is caused by heating to a temperature of 0° C. or lower and distilling off the generated glycol.
In addition, when the above titanium compound, cobalt compound and/or nickel compound is used as a transesterification reaction catalyst, there is no need to adopt special conditions for the transesterification reaction. For example, in the case of polyethylene terephthalate, the above compound A reaction mixture (lower alkyl ester of terephthalic acid and engineered ethylene glycol, or a mixture of these and their reaction products) is heated at normal pressure, under slight pressure (usually about 10 K'/CT!l or less), or under slight pressure. Under reduced pressure (usually up to about 50 degrees H9) 150 to 250 degrees Celsius
The transesterification reaction is carried out by heating the mixture to a temperature of 10.degree. C. and distilling off the alcohol generated, and then the polycondensation reaction is completed according to the method of the present invention. In carrying out the present invention, a monofunctional compound such as benzylbenzoic acid, phenolsulfonate, γ-hydroxypropanesulfonate, etc. may be bonded to the terminal end of the polystyrene obtained. A trifunctional or higher functional compound may be copolymerized in an amount that does not substantially cause the polyester to lose its thermoplasticity.

Furthermore, optional additives such as colorants, matting agents, fluorescent whitening agents, stabilizers, ultraviolet absorbers, ether bond inhibitors, dye-facilitating agents, flame retardants, and antistatic agents are added as necessary. Agents etc. may also be used.

The present invention will be explained in further detail by giving examples below.

In the examples, parts are parts by weight, and [η] is the intrinsic viscosity determined from the viscosity measured at 35° C. using orthochlorophenol as a solvent. The color tone is determined by measuring the polymer in a nitrogen stream at 20°C.
After being heat-treated at 0° C. for 20 minutes to crystallize, the surface color was measured using a Color Machine CM2O model (manufactured by Color Machine Co., Ltd.) and was expressed as an L value and a b value. The L value indicates the brightness, and the larger the value, the higher the brightness, and the b value indicates that the value is (T).
The larger it is toward the side, the greater the degree of yellow, and the greater it is toward the (toward) side, the greater the degree of blue. The softening point was measured by the penetration method. Heat resistance was determined by weight loss when heated at 290° C. for 16 hours using a Gear aging tester.
Example 1 97 parts of dimethyl terephthalate, 6 parts of ethylene glycol
4 parts and 0,005 parts of tetra-n-butyl orthotitanate as a catalyst were charged into a reactor equipped with a stirrer, a rectification column and a methanol distillation condenser, and the mixture was heated from 140°C to 23°C.
The mixture was heated to 0°C, and transesterification was carried out while methanol produced as a result of the reaction was distilled out of the system.

Three hours after the start of the reaction, the internal temperature reached 230°C, and 32 parts of methanol was distilled out. Here, 0.008 part of trimethyl phosphate as a stabilizer, 0.5 part of titanium dioxide as a matting agent,
0.002 parts of cobalt acetate and 0.002 parts of nickel acetate
1 part was added, then transferred to a reactor equipped with a stirrer and an ethylene glycol distillation condenser, and heated to 280 ml.
After reaching the temperature, the polycondensation reaction was carried out for 60 minutes while gradually reducing the pressure, and the polycondensation reaction was further carried out for 90 minutes under a reduced pressure of 0.1 to 0.0511H9.

[η] of the obtained polymer was 0.642, and the softening point was 26.
At 1.2°C, the color tone was L value 70.8, b value 4.1, and heat resistance was 8.1%. For comparison, the same procedure as in the above example was carried out except that cobalt acetate and nickel acetate were not used. The resulting polymer had a [η] of 0.641, a softening point of 260.7°C, a color tone of L value 68.9, b value 12.0, and heat resistance of 15.3%. Example 2 0.008 parts of polyorthotitanic acid (n=4), 0.001 parts of cobalt chloride, and 0.001 parts of nickel chloride were added to 130 parts of bis(β-hydroxyethyl) terephthalate, and after heating and melting, the mixture was matted. 0.5 parts of titanium dioxide was added as an agent, heated to 280°C, and then the pressure was gradually reduced to carry out a polycondensation reaction for 60 minutes.
Polycondensation reaction was carried out under reduced pressure of m1H9 for 90 minutes.

[η] of the obtained polymer was 0.641, and the softening point was 26.
At 1.3°C, the color tone was L value 70.7, b value 3.9, and heat resistance was 8.5%. For comparison, the same procedure as in the above example was carried out except that cobalt chloride and nickel chloride were not used. [η] of the obtained polymer was 0.641, the softening point was 261.0°C, the color tone was L value 69.3, b value 11.5,
Heat resistance was 16.2%. Example 3 1000 parts of terephthalic acid, 450 parts of ethylene glycol and 0.06 parts of lithium acetate as an ether bond inhibitor
The mixture consisting of 50% of the total amount of water was heated and the esterification reaction was carried out for 3 hours while distilling off the generated water.

Finally, the internal pressure was 3K2/CdG, the internal temperature was 250°C, and the esterification rate was 96%. Here, 0.008 parts of trimethyl phosphate is used as a stabilizer, and 4.32 parts of titanium dioxide is used as a matting agent.
parts, polytetra n-butyl orthotitanate (n=4
), 0.007 part of cobalt benzoate and 0.005 part of nickel carbonate were added, and the mixture was heated at 250°C under normal pressure for 20 minutes.
After heating for several minutes, the temperature was gradually raised while reducing the pressure, and finally a polycondensation reaction was carried out at 285° C. for 3 hours and 40 minutes under a reduced pressure of 0.211H9.

Claims (1)

[Claims] 1. In producing a polyester by polycondensing at least one glycol ester of a difunctional aromatic carboxylic acid and/or a low polymer thereof in the presence of a titanium compound represented by the following general formula, The polycondensation reaction is carried out in combination with a cobalt compound and 0.0001 to 0.02 parts by weight of nickel acetate, nickel chloride, or nickel carbonate per 100 parts by weight of the free acid component of the difunctional aromatic carboxylic acid. A method for producing polyester characterized by: General formula ▲ Numerical formula, chemical formula, table, etc. are available ▼ [In the formula, R is a hydrogen atom or a monovalent aliphatic group, and n is an integer of 1 or more. ]