JPS5925819A - Preparation of formed polyester article - Google Patents

Abstract

PURPOSE:To enable the preparation of the titled formed article having increased reactivity with epoxy compound and remarkably improved resistance to hydrolysis, by adding an alkali metal compound and a phosphorus compound at a specific ratio to the direct polymerization system when the degree of the esterification reaches a specific level. CONSTITUTION:Dicarboxylic acids composed mainly of terephthalic acid are esterified with glycols composed mainly of ethylene glycol. When the degree of esterification reaches >=95%, an alkali metal carboxylic acid salt (especially lithium acetate) or glycolate and a phosphorus compound (especially phosphoric acid) are added to the system separately with time lag at a ratio satisfying the relationship of formula, and the polycondensation is carried out to obtain a polyester. Before or during the forming of the polyester, 0.1-10wt% of a monofunctional epoxy compound is added to the polyester and made to react with the molten polyester to obtain the objective formed article. The amount of the alkali metal compound is preferably 0.005-0.1wt%.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing HoIJ ester having a low content of carboxyl groups.

Polyesters, represented by polyethylene terephthalate, have excellent physical and chemical properties and are used in a wide range of products such as fibers, films, and molded products.

However, polyester has the disadvantage that when it is heated to high temperatures in the presence of moisture, hydrolysis occurs, resulting in a significant decrease in strength. Such shortcomings are
This is particularly a problem when used in rubber reinforcing materials such as tire cords, or when used in papermaking canvases. The most effective method conventionally known for improving the hydrolysis resistance of polyester is to reduce the number of terminal carboxyl groups in the polyester.

As a method to reduce the number of terminal groups, this is 1.
Various proposals have already been made, including a method using melt polymerization and solid phase polymerization in combination, a method of adding carbonates such as ethylene carbonate, and a method of adding a monofunctional epoxy/compound to block terminal carboxyl groups. There are ways to do this. Among these, the method using monofunctional ebony/compound (Japanese Patent Publication No. 44-27911) allows ebony/compound to be added during molding or during the process.
It has the characteristic that it is possible to obtain molded products with a very low carboxyl group content. However, since the reaction between the monofunctional epoxy compound and the terminal carboxyl group of the polyester is relatively slow, the amount of the epoxy compound added may be increased more than the required amount during use.

Considerations such as lengthening the reaction time are necessary.
This causes an increase in costs.

Therefore, it is necessary to add a catalyst to improve the reactivity, and various methods have been proposed so far.

On the other hand, as high-purity terephthalic acid has recently become available at low cost, the so-called direct reaction method, in which dicarboxylic acid and glycol are directly reacted, has gradually become more advantageous in terms of cost compared to the conventional method that relies on dicarboxylic acid dialkyl esters. This method is becoming increasingly popular, and the advantage of the direct weight method is that it does not require a transesterification catalyst, making it easy to obtain high-quality polymers.

However, from the viewpoint of the reactivity between the ebony/compound and the carboxyl group, the polymer obtained by the direct polymerization method has the disadvantage that the reactivity is lower than that of conventional polyester containing a transesterification catalyst.

Therefore, the present inventors conducted studies to improve the reactivity between the carboxyl group of the straight-loaded polymer and the epoxy compound.

JP-A-51-134784 proposes a method in which an alkali metal salt of a carboxylic acid is added as a catalyst for the reaction between a monofunctional epoxy/compound and a carboxyl end group. However, when trying to apply this technology to the production of polymers using the direct loading method, the reaction system prior to the polycondensation stage in the direct loading method contains a large number of carboxyl groups, making it easy for alkali metals to precipitate as particles. It has been found that this results in foreign matter that not only deteriorates the quality of the molded product but also often results in a low epoxy reaction catalytic ability. Especially in JP-A-5
As disclosed in the examples of Publication No. 1-134789, when an alkali metal compound is added at the beginning of the esterification reaction, the formation of foreign substances is significant and only a product with extremely low reactivity to epoxy can be obtained. Ta.

Furthermore, it has been found that when an Epoquine compound is added to a polyester containing an alkali metal compound and subjected to a melt reaction, the degree of polymerization of the polyester is significantly reduced compared to when the polyester does not contain an alkali metal compound.

That is, by the method described above, it was not possible to obtain a polymer that had both high reactivity with Epoquine and good thermal stability when Evoquine was added.

Further, JP-A-55-12871 discloses that a monofunctional Epoquine compound and a carboxylic acid salt of an alkali metal are added during melt spinning of POIJ Knee 5 to Stell. In this method, the epoxy compound,! : It has the advantage that the degree of polymerization of polyester during the melt reaction is small, but since it is usually difficult to dissolve a sufficient amount of catalyst in the polymer, there is a limit to the reactivity improvement effect that can be obtained. .

The present inventors have made extensive studies to improve this drawback, and found that when the esterification reaction rate reaches 95% or more in the direct weight method, the alkali metal compound and the phosphorus compound are added in a specific ratio and separately. by adding the compound to a polycondensate and then subjecting it to polycondensation.

The present invention was achieved by discovering that a polymer can be obtained which maintains extremely high reactivity with epoxy and exhibits little decrease in the degree of polymerization during melt reaction with epoxy.

That is, the present invention esterifies a dicarboxylic acid mainly composed of terephthalic acid and a glycol mainly composed of ethylene glycol, and when the ester reaction rate becomes 95% or more, formula (1) f: satisfied. After adding an alkali metal carboxylate or glycolate and a phosphorus compound separately and at staggered addition times to one reaction system in an amount ratio of This is a method for producing a polyester molded product, which is characterized in that 01 to 10% by weight of a monofunctional epoxy compound is added to the polyester during molding and reacted with the molten polyester.

15≦M/P≦10 (1) In the present invention, polyester is a polyester whose repeating units are mainly composed of ethylene terephthalate units, as described above. Other repeating monomers of the polyester include components copolymerizable with ethylene terephthalate, i.e. 1, for example, adipic acid, sebacic acid, phthalic acid, isophthalic acid, 3.5->storium carboxybenzenesulfonate, diphenyl-4 ,4'-dicarboxylic acid, 1
．． 2-bis-(4-carphoki/phenoxy)ethane 1-naphthalene dicarboxylic acid, polyfunctional carboxylic acid such as trimellitic acid, 1,2-propylene glycol, 1,4-butanediol.

Examples include polyfunctional compounds such as 1.6-hexanediol, 1.4-cyclohexane dimetatool, pentaerythritol, diethylene glycol, triethylene glycol, and polyethylene glycol.

Further, the terephthalic acid used as the main raw material may contain impurities such as p-formylbenzoic acid in an amount not exceeding 2000 ppm.

Methods for esterifying dicarboxylic acid and glycol include a method of mixing dicarboxylic acid and glycol and reacting under pressure; Known methods are preferably used, such as a method in which the components are added to the reaction system separately or in a mixture for reaction, and a method in which a part of the above-mentioned reaction is conducted under reduced pressure.

As the alkali metal carboxylate used in the present invention,
Examples include salts of alkali metals such as formic acid, acetic acid, propionic acid, butyric acid, stearic acid, benzoic acid, and tartaric acid. Among these, acetates are preferred, and lithium acetate is particularly preferred. As the glycolate, ethylene glycol glycolate is preferred, and glycolate obtained by reacting a lithium compound with ethylene glycol is particularly preferred. The amount of these compounds added is 0.001 from the viewpoint of promoting the reaction between the monofunctional Evoquin compound and the polyester terminal carboxylate, the heat resistance of the polymer, and the generation of foreign matter.
~0.5 weight ratio is appropriate, but especially 0.005~0.1
Weight clerk is preferred.

In addition, the phosphorus compound referred to in the present invention is not particularly limited, but has a high residual rate in polyester even under high temperature and reduced pressure, and has a phosphorus value or
Preferred are phosphorus compounds of high valence. Such phosphorus compounds include phosphorous acid, triphenylphosphite, phosphoric acid,
Examples include trimethyl phosphate, partial methyl ester of phosphoric acid, triphenyl phosphate, and ethylene glycol phosphate, with phosphoric acid being particularly preferred.

In the present invention, the addition timing and addition amount ratio of the alkali metal compound and phosphorus compound are particularly important.

It is necessary to add the alkali metal compound and the phosphorus compound from the time when the esterification reaction rate reaches 95% or more to before the start of polycondensation. When added to a system with an esterification reaction rate of less than 95%, precipitation of alkali metal compounds as particles is significant. Therefore, the concentration of alkali metal effective as a catalyst decreases, and the improvement in reactivity with epoxy becomes extremely low.

In ordinary polyester polymerization, the esterification reaction rate is 95
Although a prepolymer with a concentration of less than 90% can be subjected to polycondensation, in the present invention, an alkali metal compound and a phosphorus compound are added after the prepolymer has a concentration of 95% or more.
It is necessary to subject it to polycondensation.

On the other hand, addition at a stage after the start of polycondensation is not convenient because not only the addition operation becomes complicated, but also a sufficient reactivity improvement effect cannot be obtained.

Further, it is necessary to add the alkali metal compound and the phosphorus compound separately and at different times after the addition of one is completed. If the two are added as a mixture, or if they are added to the reaction system at the same time even if they are separate, the alkali metal will not only be inactivated by the phosphorus compound, but also coarse particles will precipitate, impairing the quality of the polymer. This will cause significant damage. The order of addition is 0, regardless of which one comes first, the alkali metal compound or the phosphorus compound.The quantitative ratio of the alkali metal compound to the phosphorus compound is such that the metal atomic ratio M/P is 1.5 or more.
It is necessary that it is 0 or less, and it is more preferable that it is 1.75 or more and 8 or less. When it is less than 1.5, the inactivation of the alkali metal by the phosphorus compound is significant, and the
If it is larger than 0, it will melt and react with the epoxy/compound.
The degree of polymerization of polyester decreases significantly when heated. Furthermore, in the present invention, prevention of the precipitation of coarse particles due to the reaction of an alkali metal with the carboxyl group of the prepolymer is achieved not only by regulating the esterification reaction rate as described above, but also by controlling the esterification reaction rate. Regulation of conversion reaction rate and M
It has been found that this can be achieved by the synergistic effect of setting /P-q in a specific range. In other words, the 1-step stellation reaction rate is 95%.
Even if it is above, when M/P is larger than 10, precipitation of Japanese dog particles cannot be prevented to a practically sufficient extent by 1. Furthermore, in this case, the reactivity to Evoquin also decreases.

On the contrary, even if M/P is 10 or less, if the esterification reaction rate at the time of addition is less than 95%, the object of the present invention cannot be achieved.

In addition, as a method of polycondensing the reaction mixture after adding an alkali metal compound and a phosphorus compound, in -11-, there is a method in which the ethylene glycol fraction is distilled off under reduced pressure in the column section and polycondensation is carried out in a molten state, and/or Known methods such as flowing an inert gas or performing polycondensation in a solid phase under reduced pressure are employed.

Specific examples of monofunctional epoxy compounds used in the present invention include the following.

Low-boiling point evoquins such as ethylene oxide/propylene oxide, among these compounds,
In the case of 5--12-% K O-phenyl phenyl grindyl ether, the catalytic effect of the alkali metal compound of the present invention is best exhibited, and the degree of polymerization of the added polymer is less reduced, which is preferable.

The amount of the monofunctional ebogi/compound used in the present invention needs to be 0.81 to 10% by weight, preferably 0.5 to 3% by weight, based on the polyester. When the amount added exceeds 10% by weight, not only the effect of obtaining a product with low carboxyl groups, which is the object of the present invention, is saturated, but also the general properties of the product such as deterioration of color tone are impaired. Furthermore, if the amount added is less than 0.1 weight factor, sufficient carboquine reduction effect cannot be obtained.

Further, in the present invention, a monofunctional epochino compound is added to the polyester and reacted at any stage from the completion of polycondensation to molding step 1.

In other words, when a monofunctional ebogishi compound is added in the first half of polymerization, it is difficult to block and knead the terminal carboxyl groups generated in the polymerization process after addition. Since it tends to be difficult to block the terminal groups generated during membrane and molding, it is necessary to add a monofunctional epoxy at the time of spinning, film forming, and molding, or immediately before these steps.

Conventionally known methods can be used as the addition method.

Here, the most clever method is to add it near the chip intake port of a melt spinning machine or a molding machine, as disclosed in JP-A-49-55915 or d and JP-A-51-49917. However, it can be added to and mixed with dry chips in a rotary chip dryer or blender to make it adhere uniformly to the chip surface, or after drying in a rotary chip dryer.
A method of adding to a chip heated to 00 to 180 ° C. and soaking it into the chip, and further adding and mixing a monofunctional evoquin compound after melt polymerization P:f, immediately spinning, film forming without chipping, Any method such as molding can be preferably employed.

In the present invention, in addition to adding an alkali metal compound and a phosphorus compound, various known catalysts and additives may be used to accelerate the esterification reaction and polycondensation reaction, or to adjust the color tone or improve surface properties. It is also possible to use them together.

By the method of the present invention, the reaction between the terminal carboxyl group of polyester and a monofunctional epoxy compound is promoted, and polynisdel having a low carboxyl group content can be efficiently produced. The shredded polyester obtained according to the present invention has greatly improved hydrolysis resistance, and is therefore extremely effective as an industrial polyester, particularly for tire cords, fishing nets, and the like.

The present invention will be specifically explained below with reference to Examples.

In addition, the intrinsic viscosity (IV) of the polyester referred to in the present invention is measured in u, o-chlorophenol at 25°C (- means the value.
Ohl ni Q A, NALYTIOALC! HEMIS
TRY 26.・It was measured by the method described in 164 ('54) and is (I/Io'g).

Polyesters with carboxyl groups of 10 (equivalent/10'g) or less have good hydrolysis resistance and are the most stable.
can be provided.

The number of coarse particles in the polymer is determined by melt pressing polymer 10~ between two cover glasses and binding the preparation.
It is shown as the result of dividing the number of coarse particles with a diameter of 5μ or more under a dark field microscope.

All dimensions are parts by weight.

Example 1, Comparative Example 1 Reaction rate of terephthalic acid and ethylene glycol: 97
．． Section 8, -0CH2CH20-/-Misaki◎-C-Units 1
A reaction mixture (hereinafter referred to as BH
2052 parts (referred to as T) were stored in a reactor at 240°C,
1660 parts of terephthalic acid and 7 parts of ethylene glycol at normal pressure
A slurry of 44 parts (KG/TPA molar ratio 120) was fed continuously at a constant rate over a period of 4 hours and 15 minutes. The temperature was controlled at 260-245°C during slurry supply, and the temperature was controlled at 240-250°C after slurry supply to substantially complete the reaction, resulting in a BHT'ii7 reaction rate of 981%.
Obtained. 50% of this BHT was transferred to the next reaction tank and polycondensed as follows.

85 parts by weight of phosphoric acid and 0192 parts of an aqueous solution were added to the reaction system with stirring. The temperature of the reaction system at this time was 250°C. 0384 parts of lithium acetate dihydrate (
A mixture of M/P 2.2/l), 0.53 parts of antimony trioxide, and 30 parts of ethylene glycol was added to the reaction system.

Immediately, temperature increase and depressurization was started, and the degree of vacuum was 1 m in 60 minutes.
Below mHg.

The temperature was reached to 280°C, and the polycondensation reaction continued for another 6 hours, resulting in IV=0.71.0OOH group 2
5/10'g of polyethylene terephthalate was obtained. This polymer was shredded into 2X4X4 (111111) dice, and then cut into 180
It was vacuum dried at ℃ for 5 hours.

Thereafter, this polymer was spun at 290° C. using a 25 Tanφ extruder type spinning machine.

At this time, 1 weight portion of 0-phenylphenylglycidyl ether was added through the chip receiving port using a gear pump. Polyvarnish f/l/thread (7) IV thus obtained
was 0.69 and the number of C0OH groups was 2 (equivalent/106g). For comparison, a polyester yarn obtained by spinning without adding 0-phenylphenylglycidyl ether had an IVo of 70 and a COOH group of 30 (equivalent/106
g).

Examples 2 to 7, Comparative Examples 2 to 6 Polymer production, Epoquine compound addition, and spinning operations were performed in exactly the same manner as in Example 1, except that the amounts of lithium acetate and phosphoric acid added were changed as shown in Table 1. I did it. The results are shown in Table 1.

- 19 Example 8, Comparative Example 7 In Example 1, the esterification reaction rate when adding a phosphorus compound was changed as shown in Table 2. It can be seen that when the esterification reaction rate is less than 95%, the reactivity to epoxy is low.

Table 2 Comparative Example 8 The same procedure as in Example 1 was conducted except that lithium acetate, phosphoric acid, and antimony trioxide were simultaneously added to BHT under stirring.

Chip quality is IV[], 70.0OOH28 (equivalent/1
0 (!g), and the number of coarse particles in the polymer is 25
It was 107V. 0-phenyl phenyl goo 2
0- Yarn with added lindyl ether is TVo, 69, C! 0
OH19 (equivalent/106 g).

Example 9 Example M Example I was carried out in exactly the same manner except that 0.66% by weight of phenylglycidyl ether was added instead of O-phenylphenylglycidyl ether. The IV of the obtained polyester thread is 0.68,0 OOH group 5 equivalents/1
It was 06g.

Example 10 In Example 1, instead of lithium acetate, lithium hydroxide and ethylene glycol were reacted at a molar ratio of 1:5 at 150°C for 2 hours.
, 026 parts (M/P226).

The IV of the obtained thread is 0.68.0OOH is 2 (equivalent/1
06g).

Patent applicant: Toshi Co., Ltd.

Claims (1)

[Claims] A dicarboxylic acid mainly composed of terephthalic acid and a glycol mainly composed of ethylene glycol are esterified, and at the time when the esterification reaction rate reaches a coefficient of 95 or higher, a quantity ratio that satisfies the formula (1) is obtained. , Add the alkali metal carboxylate or glycolate and phosphorus compound to the reaction system fully and with staggered addition times, and further perform polycondensation,
After forming a polyester molded product, before or during molding of the polyester, a monofunctional epoxy 7 compound of 01 to 10% by weight is added to the polyester and reacted with the molten polyester to produce a polyester molded product. Method. 15≦M/P≦10 (I)