JPS6314741B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing polyester molded articles, particularly polyester molded articles having a small amount of terminal carboxyl groups.

Polyesters, especially saturated polyesters represented by polyethylene terephthalate, have many excellent properties and are therefore widely used as materials for clothing fibers, industrial fibers, films, and other molded products. However, depending on the application, better hydrolysis resistance and heat resistance are required.

In order to improve the hydrolysis resistance and heat resistance of polyester, it is effective to reduce the amount of terminal carboxyl groups in polyester, and various methods have been proposed to reduce the amount of terminal carboxyl groups. For example, a method in which phenyl glycyl ether is reacted with polyester in a molten state (see Japanese Patent Publication No. 44-27911), a method in which ethylene oxide is reacted with polyester (Japanese Patent Publication No. 47-27911),
-12891), method of reacting N-glycidyl phthalimide with polyester (Special Publication No. 12891), method of reacting N-glycidyl phthalimide with polyester
-35952), a method of reacting carbodiimide and polyester (see US Pat. No. 3,193,522), and the like have been proposed.

However, these methods require a large amount of additives in order to produce a polyester with a sufficiently low amount of terminal carboxyl groups, so it is necessary to reduce the amount of terminal carboxyl groups in the target polyester in advance by another means. Many problems arise, such as the need for a molded product, which greatly reduces the product value due to increased coloring, and the tendency to cause foaming due to the decomposition of additives during molding (during spinning). could not be applied to production.

Among the above-mentioned methods, the method using an epoxy compound having a glycidyl group bonded to an imide group, such as N-glycidyl phthalimide, did not have a sufficient effect of reducing the terminal carboxyl group, but did not cause foaming during molding. The color tone of the molded product obtained was also good. However, the addition of such an epoxy compound has the disadvantage that the degree of polymerization of the polyester decreases. As the amount of the epoxy compound added increases, the amount of terminal carboxyl groups decreases, but the degree of polymerization also decreases, and the properties of the resulting molded product are impaired. When using polyester as industrial fibers, films, and other molded products, it is necessary to maintain not only hydrolysis resistance and heat resistance, but also other mechanical properties above a certain level, so this method is also difficult. It could not be put to practical use.

The present inventor has conducted intensive studies on a method for producing polyester molded articles having a sufficiently small amount of terminal carboxyl groups and a small decrease in the degree of polymerization using the above-mentioned epoxy compound having a glycidyl group bonded to an imide. The present invention was completed based on the knowledge that the object could be achieved by blending a specific alkali metal compound in advance, adding a specific epoxy compound thereto, and melt-molding the mixture.

That is, in the present invention, the following general formula () or () is added to a saturated polyester obtained by blending and dispersing an alkali metal halide at the stage of a polycondensation reaction. [In the formula, R ₁ is a halogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group, m is an integer of 0 to 4, and when m is 2 or more, R ₁ may be the same or different.

R ₂ , R ₃ , R ₄ and R ₅ are hydrogen atoms or have 1 or more carbon atoms
R ₂ , R ₃ , R ₄ and R ₅ may be the same or different, and R ₃ and R ₄ may be bonded to each other. ] This is a method for producing a polyester molded article, which is characterized by adding at least one type of epoxy compound represented by the following and melt-molding it.

The acid components constituting the saturated polyester in the present invention include terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid,
Aromatic dicarboxylic acids such as diphenylsulfone dicarboxylic acid, diphenoxyethane dicarboxylic acid, diphenyl ether dicarboxylic acid, methyl terephthalic acid, methyl isophthalic acid, etc., succinic acid, adipic acid, sebacic acid, decanedicarboxylic acid, dodecanedicarboxylic acid Examples include aliphatic dicarboxylic acids such as cyclohexanedicarboxylic acid, alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, oxycarboxylic acids such as ε-oxycaproic acid, oxybenzoic acid, hydroxyethoxybenzoic acid, etc. Among these, aromatic dicarboxylic acids Acids are preferred, particularly terephthalic acid. In addition, in the above saturated polyester, when the acid component is a dicarboxylic acid, the glycol component includes ethylene glycol, trimethylene glycol, tetramethylene glycol,
Examples include hexamethylene glycol, decamethylene glycol, cyclohexane dimethylol, and among these, ethylene glycol and tetramethylene glycol are particularly preferred.

It is also possible to use polyoxyalkylene glycol as part of the glycol component, and examples thereof include polyoxyethylene glycol, polyoxypropylene glycol, polyoxytetramethylene glycol, and copolymers thereof. When using polyoxyalkylene glycol, its average molecular weight is preferably from 500 to
5000, more preferably 600 to 4000, particularly preferably 800 to 3000, and the amount used is about 5 to 85% by weight, preferably about 10 to 80% by weight, more preferably about 15 to 75% by weight in the copolyester. This is the amount to be copolymerized. The copolyester obtained by copolymerizing polyoxyalkylene glycol is preferably a block copolymer.

In addition, the saturated polyester may include tri- or more functional compounds such as trimethylolpropane, pentaerythritol, trimellitic acid, pyromellitic acid, etc. within a substantially thermoplastic range (for example, 1 mol% or less based on the total acid components). However, monofunctional compounds such as benzoylbenzoic acid and diphenylcarboxylic acid may also be copolymerized.

Any method may be employed to produce such polyester. For example, in the case of polyethylene terephthalate, terephthalic acid and ethylene glycol are directly esterified or dimethyl terephthalate and ethylene glycol are transesterified to produce a glycol ester of terephthalic acid and/or a low polymer thereof. A first step reaction and a second step in which the reaction product of the first step is heated under reduced pressure to distill off the generated glycol and polymerize.
It is most commonly produced by a step-by-step reaction, and the degree of polymerization varies depending on the degree of polymerization of the desired polyester molded product and cannot be absolutely specified, but the degree of polymerization is usually 0.4 or more in terms of intrinsic viscosity. , preferably 0.5 to 1.0. If even higher mechanical strength is required, the polyester obtained by the above melt polymerization method may be heated to a temperature below its melting point under reduced pressure or in a stream of inert gas such as nitrogen. It is effective to increase the altitude. The solid phase polymerization rate largely depends on the amount of terminal carboxyl groups in the polyester, and the higher the amount, the higher the rate.
Productivity can be improved. In the method of the present invention, the amount of terminal carboxyl groups in the polyester can be significantly reduced during the melt molding step, which is extremely advantageous when solid phase polymerization is required.

The above first stage reaction and second stage reaction include:
Any catalyst can be used if desired,
Additionally, additives such as colorants, matting agents, stabilizers, flame retardants, antistatic agents, dye-facilitating agents, etc. may be added as necessary.

The alkali metal halides selected from lithium, sodium, potassium, cesium, and libidium used in the present invention include, for example, sodium iodide, potassium iodide, cesium chloride, rubidium bromide, potassium bromide, Examples include compounds such as rubidium chloride, and these may be used alone or in combination of two or more.

Such a halide must be blended and dispersed in the polyester before addition of the epoxy compound, and is usually added before the polycondensation reaction of the polyester is substantially completed. however,
If added before the beginning of the polycondensation reaction of polyester, the polycondensation reaction rate tends to slow down and the color tone of the resulting polyester tends to worsen, so it should be added after the intrinsic viscosity of the polycondensation reaction mixture reaches 0.3 or higher. In particular, it is most preferably added during the polycondensation reaction of polyester, and 60 to 20 minutes before the polycondensation reaction is completed. Further, the amount of the alkali metal halogen compound added is preferably in the range of 0.005 to 0.15% by weight based on the total acid components constituting the polyester.

In addition, the general formula () or () representing the epoxy compound used in the present invention Among them, R ₁ is a halogen atom such as fluorine, chlorine, bromine, etc., or a carbon number such as methyl, ethyl, isopropyl, tertiary butyl, n-amyl, n-hexyl, methoxy, ethoxy, n-propoxy, isobutyloxy, etc. It represents an alkyl group or an alkoxy group of 6 or less, and m is an integer of 0 to 4. Also R ₂ ,
R ₃ , R ₄ and R ₅ are a hydrogen atom or the above-mentioned alkyl group having 6 or less carbon atoms, and R ₃ and R ₄ may be bonded to each other.

Specific examples of such epoxy compounds include N-glycidyl phthalimide, N-glycidyl-4-methylphthalimide, N-glycidyl-4-fluorinated phthalimide, N-glycidyl-4-chlorophthalimide, and N-glycidyl-4-ethoxyphthalimide. , N-glycidyl-4,5-dimethylphthalimide, N-glycidyl-3,4,5,6-
Tetrabromphthalimide, N-glycidyl-
4,5-dichlorophthalimide, N-glycidyl-4-n-butyl-5-bromphthalimide, N
-glycidyl succinimide, N-glycidylhexahydrophthalimide, N-glycidyl-1,
2,3,6-tetrahydrophthalimide, N-glycidylmaleimide, N-glycidyl-α,
β-dimethylsuccinimide, N-glycidyl-
α-ethylsuccinimide, N-glycidyl-α
-Propyl succinimide, N-glycidyl-α
-Methyl-β-butylsuccinimide and the like can be mentioned.

Among these epoxy compounds, N-glycidyl phthalimide, N-glycidyl succinimide, N-glycidyl hexahydrophthalimide and N-glycidyl-1,2,3,6-tetrahydrophthalimide are preferred, and N-glycidyl phthalimide is particularly preferred. . Moreover, these epoxy compounds may be used alone or in combination of two or more.

Such epoxy compounds are added during melt molding of polyester. The addition method may be arbitrary, for example, it may be dry blended into polyester powder, the epoxy compound may be melted beforehand and added, or both the epoxy compound and polyester may be melted beforehand and mixed. You may.

If the amount of the epoxy compound used is too small, the effect of reducing the amount of terminal carboxyl groups will be small, and if it is too large, the properties of the polyester will be impaired. Range is preferred, 0.1
A range of 3 parts by weight is particularly preferred, and a range of 0.3 to 1.5 parts by weight is most preferred.

In this way, a polyester prepared by blending and dispersing an alkali metal halide in advance and adding the epoxy compound thereto is melt-molded in a conventional manner. For example, the melt molding temperature is preferably higher than the melting point of the polyester and lower than 340°C, and the melt residence time is 10 seconds or higher and 30 minutes or lower. Under such molding conditions, the epoxy compound can be easily and sufficiently reacted with the terminal carboxyl group of the polyester.

According to the present invention, a polyester molded article having a sufficient degree of polymerization and having a sufficiently low amount of terminal carboxyl groups and excellent heat resistance can be easily produced using a saturated polyester having a high amount of terminal carboxyl groups. . In particular, even when heat resistance and excellent mechanical properties are strictly required for polyester molded products, it is possible to achieve a high degree of polymerization by, for example, solid-phase polymerizing polyester with a relatively high amount of terminal carboxyl groups. By easily obtaining polyester and applying the present invention to the thus obtained polyester, a polyester molded article having extremely excellent mechanical properties and heat resistance can be obtained very easily.

The present invention will be explained in further detail by giving examples below.
Parts in the examples represent parts by weight, and the intrinsic viscosity is 4:4 when tetrachloroethane and phenol are used as solvents.
It was determined from the value measured at 35°C using the mixed solvent mixed in step 6. The amount of terminal carboxyl group was determined by the method of A. Conix [Macromol.Chem 26226 (1958)].
The hydrolysis resistance was evaluated by the increase in the amount of carboxyl groups when the obtained molded product was immersed in water at 140°C for 48 hours.

Example 1 50 parts of dimethyl terephthalate, 31 parts of ethylene glycol, and 0.031 part of calcium acetate dihydrate and 0.02 part of antimony trioxide as catalysts were charged into an autoclave equipped with a distillation column and a condenser, and the temperature was gradually raised from 140°C. The methanol produced by the reaction was expelled to complete the transesterification reaction. 0.017 phosphorous acid as a stabilizer to the resulting reactant
Add 0.15% of titanium dioxide as a scraping agent.
part was added. The mixture thus obtained was heated to 285°C.
The temperature is gradually raised to , and the pressure is gradually reduced to
Polymerization was carried out for 170 minutes under a reduced pressure of 0.8 mmHg, at which point 0.004 part of potassium iodide was added, and the polymerization was further carried out for 30 minutes.
The reaction was carried out under reduced pressure of mmHg to obtain a saturated polyester polymer having an intrinsic viscosity of 0.71 and a carboxyl group content of 20 equivalents/10 ⁶ g. The obtained saturated polyester was extruded into a ribbon shape and then cut into granules.

0.5 part of N-glycidyl phthalimide was dry-blended with 50 parts of the obtained granules, and the resulting mixture was heated from an extruder to about 290°C for an average residence time of 4.
After a minute, the yarn was extruded through a die with a diameter of 0.5 mm to obtain an undrawn yarn, which was then stretched 5.5 times at 80°C and further heat-treated at 210°C. The obtained drawn yarn had a good hue, an intrinsic viscosity of 0.61, and a carboxyl group content of 2 equivalents/10 ⁶ g. Carboxyl group content after hydrolysis resistance evaluation is 15 equivalents/10 ⁶ g
It was hot.

Comparative Example 1 Example 1 except that potassium iodide was not added in the polyester polycondensation step in Example 1.
The drawn yarn obtained under the same conditions as above had a good hue, but had an intrinsic viscosity of 0.69 and a carboxyl group content of 16 equivalents/
10 ⁶ g, and the carboxyl group content after hydrolysis resistance evaluation was 55 equivalents/10 ⁶ g.

Comparative Example 2 The same conditions as in Example 1 were used, except that potassium iodide was not used in the polyester polycondensation step in Example 1, and 0.004 part of potassium iodide was added at the same time when N-glycidyl phthalimide was added. The obtained drawn yarn had a good hue, but the intrinsic viscosity
0.68, the carboxyl group content is 13 equivalents/10 ⁶ g, and the carboxyl group content after hydrolysis resistance evaluation is
It was 43 equivalents/10 ⁶ g.

Comparative Example 3 Obtained under the same polycondensation reaction conditions as Example 1, intrinsic viscosity 0.71, carboxyl group content 20 equivalents/10 ⁶ g
of saturated polyester polymer for 50 parts of the polymer in a molten state without being removed from the autoclave.
Added 0.5 part of N-glycidyl phthalimide, 0.8
The reaction was further carried out at 285° C. for 10 minutes under reduced pressure of mmHg.
The obtained saturated polyester had an intrinsic viscosity of 0.73 and a carboxyl group content of 2 equivalents/10 ⁶ g. The obtained saturated polyester was extruded into a ribbon shape and then cut into granules.

Fifty parts of the obtained granules were spun and drawn in the same manner as in Example 1 except that N-glycidyl phthalimide was not added to obtain a drawn yarn. The obtained drawn yarn was colored yellowish, had an intrinsic viscosity of 0.69, and had a carboxyl group content of 6 equivalents/10 ⁶ g. Furthermore, the carboxyl group content after hydrolysis resistance evaluation was 24 equivalents/
It was 10 ⁶ g.

Example 2 50 parts of dimethyl terephthalate, 31 parts of ethylene glycol, and 0.031 part of calcium acetate dihydrate and 0.02 part of antimony trioxide as catalysts were charged into an autoclave equipped with a distillation column and a condenser, and the temperature was gradually raised from 140°C. The methanol produced by the reaction was expelled to complete the transesterification reaction. 0.017 phosphorous acid as a stabilizer to the resulting reactant
and 0.004 parts of potassium iodide, and 0.15 parts of titanium dioxide as a polishing agent. The mixture thus obtained was gradually heated to 285°C,
Then, the pressure was gradually reduced to 0.8 mmHg, and the reaction was carried out to obtain a saturated polyester having an intrinsic viscosity of 0.71. The polymerization reaction time was 240 minutes. The carboxyl group content of this saturated polyester is 23 equivalents/10 ⁶
It was hot at g. The obtained saturated polyester was extruded into a ribbon shape and then cut into granules.

0.5 part of N-glycidyl phthalimide was dry-blended with 50 parts of the obtained granules, and the resulting mixture was heated from an extruder to about 290°C for an average residence time of 4.
After a minute, the yarn was extruded through a nozzle with a diameter of 0.5 mm to obtain an undrawn yarn, which was then drawn at 80° C. by a factor of 5.5 and then heat-treated at 210° C. The obtained drawn yarn was colored yellow, but had an intrinsic viscosity of 0.62 and a carboxyl group content of 2 equivalents/
It was 10 ⁶ g. The carboxyl group content after hydrolysis resistance evaluation was 17 equivalents/10 ⁶ g.

Example 3 Intrinsic viscosity 0.71 obtained by the same method as the polycondensation reaction method of saturated polyester described in Example 1,
A saturated polyester chip containing carboxyl group content of 20 equivalents/10 ⁶ g of potassium iodide was subjected to solid phase polymerization for 24 hours in a tumbler-type reactor heated at 220°C and rotated at 4 revolutions per minute under a vacuum of 1 mmHg. The reaction was carried out, the intrinsic viscosity was 0.95, and the carboxyl group content was
12 equivalents/10 ⁶ g of saturated polyester were obtained.

0.5 part of N-glycidyl phthalimide was added to this saturated polyester chip in the same manner as in Example 1, and the drawn yarn obtained by spinning and drawing had a good hue, an intrinsic viscosity of 0.89, and a carboxyl group content of 2. The equivalent weight was 10 ⁶ g. The carboxyl group content after hydrolysis resistance evaluation was 13 equivalents/10 ⁶ g.

Example 4 Obtained under the same polycondensation reaction conditions as in Example 1. Intrinsic viscosity 0.71, carboxyl group content 20 equivalents/10 ⁶
The saturated polyester polymer (g) was extruded into a ribbon shape and then cut into granules.

0.5 parts of N-glycidyl succinimide was dry-blended with 50 parts of the obtained granules, and the resulting mixture was extruded from an extruder at approximately 290°C for an average residence time of 4 minutes through a die with a diameter of 0.5 mmφ to form an undrawn yarn. The undrawn yarn was then drawn 5.5 times at 80°C and further heat-treated at 210°C. The obtained drawn yarn had a good hue, an intrinsic viscosity of 0.62, and a carboxyl group content of 2 equivalents/10 ⁶ g. Carboxyl group content after hydrolysis resistance evaluation is 14 equivalents/10 ⁶
It was hot at g.

Comparative Example 4 Example 3 except that potassium iodide was not added in the polyester polycondensation step in Example 4.
The drawn yarn obtained under the same conditions as above had a good hue, but the intrinsic viscosity was 0.64 and the carboxyl group content was 17 equivalents/10 ⁶ g, and the carboxyl group content after hydrolysis resistance evaluation was 57 equivalents/10 It was ^6g .

Claims (1)

[Claims] 1. The following general formula () or () is added to a saturated polyester obtained by blending and dispersing an alkali metal halide at the stage of a polycondensation reaction. [In the formula, R ₁ is a halogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group, m is an integer of 0 to 4, and when m is 2 or more, R ₁ may be the same or different. R ₂ , R ₃ , R ₄ and R ₅ are hydrogen atoms or have 1 or more carbon atoms
R ₂ , R ₃ , R ₄ and R ₅ may be the same or different, and R ₃ and R ₄ may be bonded to each other. ] A method for producing a polyester molded product, which comprises adding at least one epoxy compound represented by the following and melt-molding the product.