JPS6057445B2 - 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 a high softening point and good color tone.

Aromatic polyesters, whose main components are difunctional aromatic carboxylic acids and glycols, have excellent mechanical, physical, and chemical properties, and are widely used in fibers, films, and other molded products. There is.

Among aromatic polyesters, polyesters containing terephthalic acid as the main acid component and ethylene glycol, tetramethylene glycol, hexamethylene glycol or cyclohexane-1,4-dimethylol as the main glycol component are particularly important. 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 catalyst used will affect the reaction rate and
The quality of the resulting product is greatly affected. Titanium compounds such as tetrabutyl titanate have been known to have excellent polycondensation catalytic ability.

However, when such a titanium compound is used, the resulting polyester I tends to be yellowish, and especially when used in an amount sufficient to achieve an industrial production rate, the resulting polyester exhibits a marked yellow color and also has a low softening point. do. Several methods have been proposed for preventing coloring when such titanium compounds are used. In other words, Tokuko Koko 1977-
No. 222 Wani Publication 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-titatonic acid is easily deteriorated, making it difficult to store and handle it, and neither of these methods can be used industrially. This is not an appropriate method. Moreover, these methods only yield polyesters with low softening points. This drawback causes the generation of scum during processing of molded products, especially fibers, films, etc., and staining of the resulting products. As a result of intensive research into a method of polycondensing polyester with a high softening point and good color tone using a titanium compound, the inventors of the present invention found that a polyester obtained by reacting tetrabutyl titanate and trimellitic acid as a polycondensation melting medium was found. It has been found that the above objectives can be achieved by using the reaction product and in combination with specific amounts of a fluorescent agent and a blue dye.

The present invention was completed as a result of further intensive research based on this knowledge. That is, the present invention provides a polycondensation reaction of at least one glycol ester of a difunctional aromatic carboxylic acid and/or a low polymer thereof to produce a polyester, and a tetraalkyl titanate as a polycondensation catalyst and the following general formula: [1] [In the formula, n represents an integer of 2 to 4.

] 5 to 500 ppm based on the polyester obtained by reacting the aromatic polycarboxylic acid or its anhydride represented by Fluorescent agents in the range and 0.
A3 expressed by the following [■] formula in the range of 1 to 10 ppm
This is a method for producing polyester, which is characterized by blending a compound.

The difunctional carfozoic acid glycol ester used in the present invention may be produced by any method.

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

In addition, difunctional aromatic carboxylic acids other than terephthalic acid,
For example, isophthalic acid, naphthalene dicarboxylic acid, diphenyl dicarboxylic acid, diphenyl sulfone dicarboxylic acid,
It may be diphenylmethanedicarboxylic acid, diphenyletherdicarboxylic acid, diphenoxyethanedicarboxylic acid, β-hydroxyethoxybenzoic acid, etc., or a part of the main component difunctional aromatic carboxylic acid may be substituted with other difunctional aromatic acid. group carboxylic acids and/or difunctional aliphatic carboxylic acids such as sebacic acid, adipic acid, oxalic acid, 1.4
- Difunctional alicyclic carboxylic acids such as cyclohexanedicarboxylic acid or ester-forming derivatives thereof may be substituted. As the glycol, ethylene glycol is mainly used, 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 a glycol component 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 performed between terephthalic acid and ethylene glycol, a transesterification reaction is performed between a lower alkyl ester of terephthalic acid and ethylene glycol, or an addition reaction is performed between terephthalic acid and 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 employing a transesterification method, the reaction product of an aromatic polycarboxylic acid or its anhydride used as a polycondensation catalyst in the present invention and a tetraalkyl titanate can also be used as a transesterification catalyst, This is also a good thing to do. The polycondensation catalyst used in the method of the present invention has the following general formula Ti(0R)4 [wherein R represents an alkyl group].

] and the following general formula [where n represents an integer of 2 to 4].

] It is a reaction product with an aromatic polyhydric carboxylic acid or its anhydride.

When the alkyl group represented by R in the general formula is an isopropyl group, a propyl group, or a butyl group, the above-mentioned tetraalkyl titanate is tetraisopropyl titanate,
Tetrapropyl titanate and tetrabutyl titanate are preferred. In addition, aromatic polycarboxylic acids or their anhydrides include phthalate, trimellitic acid, hemimellitic acid,
Pyromellitic acid and anhydrides thereof are preferred. It is a reaction product of the above-mentioned tetraalkyl titanate and an aromatic polycarboxylic acid or its anhydride, and this reaction is carried out by dissolving part or all of the aromatic polycarboxylic acid or its anhydride in a solvent, Drop the tetraalkyl titanate, 0,
Approximately three or more powders may be reacted at a temperature of C to 200C.

The reaction pressure at this time is not particularly limited, and normal pressure is sufficient.
Note that any solvent that can dissolve part or all of the aromatic polyhydric carboxylic acid or its anhydride can be used, and ethanol, ethylene glycol, benzene, etc. are particularly preferred. The molar ratio of the tetraalkyl titanate and the aromatic polycarboxylic acid or its anhydride in this reaction can vary over a wide range, but if the amount of tetraalkyl titanate is too large, the color tone and softening point of the resulting polyester tend to deteriorate. On the other hand, if the amount of tetraalkyl titanate is too small, it tends to be difficult for the polycondensation reaction to proceed sufficiently.
Aromatic polycarboxylic acid or its anhydride per mole ↓～
Preferably, it is used in a proportion of 2 mmol.

The reaction product of the tetraalkyl titanate and the aromatic polycarboxylic acid or its anhydride thus obtained (hereinafter referred to as titanium aromatic polycarboxylic acid) can be used as it is, or it can be diluted with acetone etc. Then, it may be re-purified and used.

There is no need to limit the amount 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 raw material for polyester. 0.001 to 0 in terms of titanium atom for the difunctional carboxylic acid component
．． 05 mol%, preferably 0.005-0.02 mol%
It is. The addition time may be any time before the polycondensation reaction is completed, but it is preferably added between before and immediately after the start of the polycondensation reaction. In particular, when used as a transesterification catalyst, it is preferable to add the above amount between before and immediately after the start of the transesterification reaction. Note that other polycondensation reaction catalysts such as antimony compounds, germanilam compounds, etc. can also be used within the scope of the purpose of the present invention. Further, as the fluorescent agent used in the method of the present invention, any commercially available fluorescent agent can be used.

For example, Ubitex 0B [2●5-
Bis(5″-t-butylbenzoxolyl(2))-thiophene], manufactured by Eastman Chemicals 0B-1 [4
・4''-bis(benzoxazol-2-yl)stilbene] etc. Among them, 0B-1 is preferable.The amount used is 5% based on the polyester obtained.
It should be in the range of ~500ppm and 10-400ppm
A range of pm is preferred. If an amount outside this range is used, a sufficient hue improvement effect cannot be obtained. The compound used in combination with the above fluorescent agent is represented by the following formula.

This compound is a blue dye manufactured by Sandoz Co., Ltd. (hereinafter sometimes referred to as Terrasol Blue RLS), and the amount used is 0.1 to 10% based on the polyester obtained.
ppm, with a range of 0.5 to 3 ppm being particularly preferred.

If the amount is outside this range, the hue cannot be sufficiently improved even if the fluorescent agent is used in an appropriate amount. The fluorescent agent and Terrasol Blue RLS may be added at any time before the polycondensation reaction is completed, but they are usually added between before and immediately after the start of the polycondensation reaction.

Further, it may be added during or before synthesizing the glycol ester of difunctional carboxylic acid and/or its low polymer to be subjected to the polycondensation reaction. Upon addition, the fluorescent agent and Terrasol Blue M3 may be added simultaneously or separately in any order. ) The polycondensation reaction in the present invention does not require special conditions, and the conditions employed when polycondensing glycol esters of difunctional carboxylic acids and/or their low polymers to form polyesters are the same. Adopted voluntarily.

In the case of polyethylene terephthalate, generally, ethylene glycol ester of terephthalic acid and/or its low polymer to which the above amount of titanium aromatic polycarboxylic acid has been added is heated under reduced pressure to a temperature above its melting point and below 300°C. A method is adopted in which the polycondensation reaction is carried out by distilling off the generated glycol. In addition, when titanium aromatic polycarboxylic acid is also used as a transesterification catalyst, there is no need to adopt special conditions for the transesterification reaction. For example, in the case of polyethylene terephthalate, the above amount of Reaction mixture to which titanium carboxylate is added (lower alkyl ester of terephthalic acid and ethylene glycol or a mixture of these and their reaction products)
under normal pressure, slightly increased pressure (usually about 10k91CF1f or less), or slightly reduced pressure (usually up to about 50TIrmHg)
After the transesterification reaction is carried out by heating to 150 to 250°C and distilling off the generated alcohol, the polycondensation reaction is then completed. In carrying out the present invention, a monofunctional compound such as benzylbenzoic acid, phenol sulfonate, γ-hydroxypropane sulfonate, 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, stabilizers, ultraviolet absorbers, ether bond inhibitors, dye-facilitating agents, flame retardants, antistatic agents, etc. may be used as necessary. good.

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 200% when the polymer is placed in a nitrogen stream.
After crystallization by heat treatment at .degree. C. for 2 minutes, the surface color was measured using Color Machine CM (manufactured by Color Machine Co., Ltd.) and expressed as L value and b value. The L value indicates brightness, and the larger the value, the higher the brightness. The larger the b value is on the (+) side, the greater the degree of yellow, and the greater the value is on the (-) side, the greater the degree of blue. The softening point was measured by the penetration method. Example 1 (a) Preparation of catalyst Add 0.0 parts of trimellitic anhydride to 2.5 parts of ethylene glycol.
After dissolving 8 parts, 0.7 parts of tetrabutyl titanate (mumol relative to trimellitic anhydride) was added dropwise, and the mixture was maintained at 80'C in air under normal pressure for 6-particle reaction ripening.

After that, it was cooled to room temperature, 15 parts of acetone was added, and the precipitate was removed to NO. It was filtered using Goto paper and dried at ~100°C for 2 hours. The titanium content of the precipitate was 11.5% by weight. (b) Synthesis of polyester 9708 parts of dimethyl terephthalate, 6 parts of ethylene glycol, and 0.3 parts of manganese acetate as a transesterification catalyst were charged into a reactor equipped with a stirrer, a rectification column, and a methanol distillation condenser, and heated to 140'C. The reaction mixture was heated to 230'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 tons of methanol was distilled out. Here, 0.18 parts of trimethyl phosphate was added as a stabilizer, 0.26 parts of the precipitate obtained in (a) above was added as a polycondensation catalyst, and 0B was added as a fluorescent agent.
-1 (manufactured by Eastman Chemicals) 150ppm Terrasol Blue RLSl. 5 ppm and 4 parts of titanium dioxide as a matting agent were added, and then the reaction mixture was transferred to a reactor equipped with a stirrer and a glycol distillation condenser, and the temperature was gradually increased from 230°C to 285°C and at normal pressure. The polycondensation reaction was carried out while lowering the pressure to a high vacuum of 1 wLHg. The total polycondensation reaction time was 3 hours and 30 minutes [η] 0.
648 polymer was obtained. The softening point of this polymer is 26
The temperature was 1.0° C., and the color tone was L value 82.1 and b value 4.9.
Comparative Example 1 Tetrabutyl titanate 0.0% was used instead of the precipitate obtained in Example 1-(a). Polyester was synthesized in the same manner as in Example 11 (b) except that the nodule was used.

[η] of the obtained polymer was 0.645, and the softening point was 26.
0.7℃, color tone L value 69. The b-value pressure of 2 and the softening point were low, and the color tone also deteriorated. Examples 2 to 6 The same procedure was carried out except that in place of the trimethic anhydride used in Example 1-(a), various aromatic polycarboxylic acids listed in Table 1 were used in twice the molar amount relative to tetrabutyl titanate. Example 1-(a) was obtained in the same manner as in Example 1-(a), except that each precipitate was used in the amounts listed in Table 1.
Polyester was synthesized in the same manner as in (1).

The results were as shown in Table 1. Examples 7 to 9 and Comparative Examples 2 to 4 Fluorescent agent (0B-1) used in Example 1-(Example)
The same procedure as in Example 1 was carried out except that the amounts of Terazol Blue R and Terasol Blue R used were changed as shown in Table 2.

Claims (1)

[Claims] 1. When producing a polyester by polycondensation reaction of at least one glycol ester of difunctional aromatic carboxylic acid and/or its low polymer, tetraalkyl titanate as a polycondensation catalyst and the following general formula [I]▲There are mathematical formulas, chemical formulas, tables, etc.▼・・・・・・[I]
In the formula, n represents an integer of 2 to 4. 5 to 500 ppm based on the polyester obtained by using the reaction product obtained by reacting the aromatic polycarboxylic acid represented by Fluorescent agents in the range and 0.
A method for producing polyester, which comprises blending a compound represented by the following formula [II] in a range of 1 to 10 ppm. ▲There are mathematical formulas, chemical formulas, tables, etc.▼・・・・・・[II]
2 The reaction product used as a polycondensation catalyst is a tetraalkyl titanate and the following general formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ [ In the formula, n represents an integer of 2 to 4. The method for producing a polyester according to claim 1, which is a reaction product obtained by reacting in advance an aromatic polycarboxylic acid represented by the following formula or its anhydride. 3 Claims in which the tetraalkyl titanate that is one component of the reaction product used as a polycondensation catalyst is at least one kind of tetraalkyl titanate selected from the group consisting of tetraisopropyl titanate, tetrapropyl titanate, and tetrabutyl titanate. A method for producing polyester according to item 1 or 2. 4. The aromatic polycarboxylic acid or its anhydride, which is the other component of the reaction product used as a polycondensation catalyst, is from the group consisting of phthalic acid, trimellitic acid, hemimellitic acid, pyromellitic acid, and anhydrides thereof. The method for producing a polyester according to any one of claims 1 to 3, wherein the polyester is at least one selected aromatic polycarboxylic acid or its anhydride. 5 Claim 1, wherein the difunctional aromatic carboxylic acid glycol ester and/or its low polymer is a terephthalic acid glycol ester and/or its low polymer
A method for producing polyester according to any one of Items 1 to 4.