JPS5929602B2 - 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 thermal stability and color tone.

Polyesters, particularly polyethylene terephthalate or polyesters containing ethylene terephthalate as a main component, have many excellent properties and are therefore widely used as materials 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 products with commercial value only by using a catalyst, and the type of polycondensation catalyst used will affect the reaction rate and the product obtained. quality is greatly affected. Tetraalkyl orthotitanates such as tetrabutyl orthotitanate have been known to have excellent polycondensation catalytic ability.

However, when tetrabutyl orthotitanate is used, the resulting polyester tends to be yellowish, and particularly when used in an amount sufficient to achieve an industrial production rate, the resulting polyester exhibits a deep yellow color. A method for preventing coloring when using this titanium compound has been proposed. That is, Japanese Patent Publication No. 48-2229 discloses a method using titanium hydride;
No. 7-26597 discloses a method using α-titanic acid. However, with the former method, it is not easy to powderize titanium hydride, and with the latter method, α-
Titanic acid is susceptible to deterioration and is not easy to store and handle, making it unsuitable for industrial use. As a result of intensive research into polyester polycondensation methods using titanium compounds that do not have these drawbacks, the present inventors found that if tetrabutyl orthotitanate or this polymer is coexisting with nickel acetate for a polycondensation reaction, the color tone can be improved. It has been found that a polyester having good properties and good thermal stability can be obtained very easily.

The present invention was completed as a result of extensive research based on this knowledge. That is, the present invention involves polycondensation reaction of at least one difunctional aromatic carboxylic acid glycol ester and/or its low polymer in the presence of a titanium compound represented by the following general formula. A polyester characterized in that the condensation reaction is carried out in combination with 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. This is the manufacturing method.

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, diphenyl dicarboxylic acid, diphenylmethane dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenoxyethane dicarboxylic acid, β
-Hydroxyethoxybenzoic acid or ester-forming derivatives thereof. Further, 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.

Other aliphatic and alicyclic glycols such as tetramethylene glycol, trimethylene glycol, and cyclohexane-1,4-dimethanol may also be used. A method for producing a glycol ester and/or a low polymer thereof from such an acid component and glycol is, for example, for 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 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. Especially when using the transesterification method,
The general formula (1) used as a polycondensation catalyst in the present invention
) and/or the nickel compound described below can be used as a transesterification catalyst,
This is also a good thing to do. The above general formula (1 oki, R is a hydrogen atom or a monovalent aliphatic group,
This monovalent aliphatic group is preferably an alkyl group having 1 to 8 carbon atoms, particularly preferably an alkyl group having 1 to 5 carbon atoms.

n is an integer of 1 or more, usually 1 to 50, preferably 1
~25 integer. Preferred specific examples of such titanium compounds include orthotitanic acid, tetra-n-butyl orthotitanate, tetrapropyne orthotitanate, tetraethyl orthotitanate, tetramethyl orthotitanate, 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. The nickel compound used in combination with the titanium compound is nickel acetate, nickel chloride, or nickel carbonate.

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

The amount of the above-mentioned nickel compound used is 0.0001 to 0.02 parts by weight, preferably 0.0005 to 0.01 parts by weight, per 100 parts by weight of the difunctional aromatic carboxylic acid component used as the polyester raw material in terms of free acid. It is necessary to do so.

Here, if the amount of the nickel compound used is less than 0.0001 part by weight, the effect of improving the hue of the polyester obtained is small, and if it exceeds 0.02 part by weight, the hue of the polyester becomes black.

Further, the timing of its addition is not particularly limited, but it should be added before the reaction mixture becomes 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, or may be added separately. The polycondensation reaction carried out in the presence of the titanium compound and nickel compound does not require special conditions, and glycol esters of difunctional aromatic carboxylic acids and/or their low polymers are polycondensed to form polyesters. The conditions adopted when doing so are arbitrarily adopted.

In the case of polyethylene terephthalate, generally ethylene glycol ester of terephthalic acid and/or its low polymer mixed with the above amount of titanium compound and nickel compound are heated under reduced pressure to a temperature above its melting point and below 300'C. A method is adopted in which the generated glycol is distilled off to cause a polycondensation reaction. In addition, when the above titanium 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 titanium compound in the above amount as well as/
Alternatively, a reaction mixture containing a nickel compound (lower alkyl ester of terephthalic acid and ethylene glycol, or a mixture of these and their reaction products) is heated under normal pressure, a slight pressure (usually about 10 kg/Crl or less), or a slight pressure. Under reduced pressure (usually up to about 50m7!LHg) 150-25
The transesterification reaction may be carried out by heating to 0° C. and distilling off the generated alcohol, and then the polycondensation reaction may be 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 obtained polyester. 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. 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 Ω is the intrinsic viscosity determined from the viscosity measured at 35° C. using orthochlorophenol as a solvent. The color tone was expressed by the L value and b value obtained by heat-treating the polymer at 200°C for 20 minutes in a nitrogen stream to crystallize it, and then measuring the surface color with a Color Machine CM-20 model (manufactured by Color Machine Co., Ltd.). . The L value indicates the brightness, and the larger the value, the higher the brightness.The larger the b value is toward the . The softening point was measured by the penetration method. Example 1 97 parts of dimethyl terephthalate, 6 parts of ethylene glycol
4 parts and 0.005 parts of tetrabutyl titanate as catalyst
A portion of the mixture was charged into a reactor equipped with a stirrer, a rectification column, and a methanol distillation condenser, and heated from 140°C to 23°C to carry out a transesterification reaction while distilling methanol produced as a result of the reaction 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 and 0.002 part of nickel acetate were added as stabilizers. Thereafter, the reaction mixture was transferred to a reactor equipped with a stirrer and an ethylene glycol distillation condenser, and the temperature was gradually raised from 230°C to 285°C, and at a temperature of 0.3°C from normal pressure.
The polycondensation reaction was carried out while lowering the pressure to a high vacuum of m1H9. A total of 10.648 polymers were obtained in a total polycondensation reaction time of 3 hours and 40 minutes. The softening point of this polymer is 260.9℃
The color tone had an L value of 71.3 and a b value of 43. For comparison, the same procedure as in the above example was carried out except that nickel acetate was not used.

The resulting polymer had an Ω of 0.641 and a softening point of 260.
At 7°C, the color tone was L value 68.9 and b value 12.0. Example 2 0.008 parts of polyorthotitanic acid (n-4) and 0.001 parts of nickel chloride were added to 130 parts of bis(β-hydroxyethyl) terephthalate, and after heating and melting, 0.5 parts of titanium dioxide was added as a matting agent. 280 parts and further heated.
After reaching ℃, it took 60 minutes while gradually reducing the pressure to 0.
．． 1~0.05m7! LHf! The pressure was reduced to , and the polycondensation reaction was continued for an additional 90 minutes in this state.

The obtained polymer [1 is 0.641, the softening point is 261
．． At 3°C, the color tone was L value 71.6 and b value 4.1. For comparison, the same procedure as in the above example was carried out except that nickel chloride was not used.

The obtained polymer had a softening point of 0.641 and a softening point of 261.
At 0°C, the L value was 69.3 and the b value was 11.5. 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 esterification reaction was carried out over a period of 3 hours while heating the mixture and distilling off the generated water.

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 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 component. A method for producing polyester. 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. ]