JPH06128364A - Production of polybutylene terephthalte copolymer - Google Patents

Abstract

PURPOSE:To produce the title copolymer industrially at a high productivity without causing foaming due to a poly(alkylene oxide) glycol. CONSTITUTION:The copolymer is produced by esterifying or transesterifying terephthalic acid or its ester-forming deriv. with 1,4-butanediol to give bis (hydroxybutyl) terephthalte and/or its low polymer and subjecting the reaction product to polycondensation under a reduced pressure under such a condition that at an arbitrary time after the reaction pressure reaches 20Torr and before the intrinsic viscosity [eta] of the resulting polymer reaches 0.70, a poly(alkylene oxide) glycol in an amt. of 0.1-10wt.% based on the polymer is added to the reaction system and the polycondensation is continued.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a polybutylene terephthalate copolymer. More specifically, it relates to a method for polymerizing polybutylene terephthalate, which is excellent in polymerization productivity and has improved toughness of a molded product of a small amount of poly (alkylene oxide) glycol.

[0002]

2. Description of the Related Art Polybutylene terephthalate (hereinafter referred to as P
BT) has a high crystallization rate, excellent heat resistance, mechanical properties, and chemical resistance, and is widely used as an engineering plastic for electrical / electronic parts and automobile parts mainly in injection molding applications. However, it has the drawback of low toughness and impact resistance. It is known that various rubber components are added to improve this point, but it is necessary to use a specially modified rubber in order to enhance the adhesiveness at the interface between the PBT and the rubber. There was a problem that the fluidity of the product was impaired and the cost increased. On the other hand, JP-A-51-109996 discloses that PBT is copolymerized with a small amount of poly (alkylene oxide) glycol to enhance toughness and impact resistance without impairing fluidity.

[0003]

In the polymerization of polyester, a copolymerization component such as poly (alkylene oxide) glycol is added to the reaction system before the start of transesterification or esterification reaction or before the start of polycondensation reaction. This is usually done, and the publication also discloses addition before transesterification.

However, when attempting to industrially carry out these methods, foaming occurs in the reaction system, and as a result, the reaction liquid level rises, and in a remarkable case, there is a problem that the distillation circuit is blocked or bumping occurs. I knew it was. For this reason, in the production of such a copolymer, the amount charged into the reaction can has to be suppressed to a lower level than the can volume, resulting in poor productivity. This problem is peculiar to PBT polymerization, and when the poly (alkylene oxide) glycol is not contained or when the concentration is high, the foaming is slight, but at a low concentration such as 10% by weight or less, the foaming does not occur. It turned out to be greatly encouraged. Further, in the so-called direct weight method using terephthalic acid as a raw material, this foaming phenomenon is particularly remarkable, and when poly (alkylene oxide) glycol is added at a stage from before the esterification reaction start to before the polycondensation start, industrial Production was extremely difficult.

The object of the present invention is to provide a small amount of poly (alkylene oxide) glycol copolymerized PBT useful for molding.
In the production of the above, it is to propose a technique for avoiding such a foaming phenomenon and polymerizing the modified PBT with high productivity, particularly a technique for suppressing a remarkable foaming phenomenon in the direct weight method.

[0006]

In order to solve the above problems, the present invention has the following constitution. That is, terephthalic acid or its ester-forming derivative and 1,4-butanediol are esterified or transesterified to form bis (hydroxybutyl) terephthalate and / or its low polymer, and polycondensation reaction is performed under reduced pressure. When a polybutylene terephthalate copolymer is produced by reacting poly (alkylene oxide) glycol as a copolymerization monomer, the reaction pressure is 2 in the polycondensation reaction.
After reaching 0 torr, the intrinsic viscosity [η] of the polymer is 0.
At any time prior to reaching 70, the
A method for producing a polybutylene terephthalate copolymer, which comprises adding 1 to 10% by weight of poly (alkylene oxide) glycol under reduced pressure and then performing polycondensation.

Poly (alkylene oxide) referred to in the present invention
Examples of the glycol include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, poly (ethylene oxide-propylene oxide) copolymer, poly (ethylene oxide-tetrahydrofuran) copolymer and the like. Of these, polytetramethylene glycol is particularly preferable. Moreover, you may use together 2 or more types of poly (alkylene oxide) glycols. The number average molecular weight of the poly (alkylene oxide) glycol is preferably 400 to 6000, more preferably 800 to 4000. The addition amount of poly (alkylene oxide) glycol is O. It is necessary to make it 1 to 10% by weight, and more preferably 0.3 to 7% by weight. If it is less than 0.1%, the effect of improving the toughness and impact resistance is poor, and if it exceeds 10% by weight, the rigidity of the molded product is remarkably lowered and it becomes unsuitable for use as engineering plastics.

The poly (alkylene oxide) glycol is added after the reaction pressure in the polycondensation reaction step reaches 20 torr, and the reaction pressure is 1
It is preferable that the intrinsic viscosity reaches 0.60 after reaching 0 torr. If poly (alkylene oxide) glycol is added before the reaction pressure reaches 20 torr, by-produced tetrahydrofuran (hereinafter referred to as THF) is often generated, which serves as a foaming source and a small amount of poly (copolymerized monomer) which is a copolymerization monomer in the reaction system. When the alkylene oxide) glycol component is present, it acts as a surfactant and synergistically leads to remarkable foaming, so that the foaming phenomenon cannot be avoided.

The poly (alkylene oxide) glycol is added before the time when the intrinsic viscosity [η] of the reaction system polymer reaches 0.70. Addition at the time when the intrinsic viscosity [η] of the polymer exceeds 0.70 increases the time required for completion of the reaction, and
There is a problem that the phase separation of the poly (alkylene oxide) glycol into the polymer is remarkable and the mechanical properties of the obtained polymer are deteriorated. Further, addition of poly (alkylene oxide) glycol needs to be performed under reduced pressure. When the pressure is once returned to the normal pressure and added, not only the time loss when re-entering the reduced pressure polymerization is large, but also the polymerization reactivity after the high vacuum is reached is lowered.

The ester-forming derivative of terephthalic acid referred to in the present invention means a lower alkyl ester, and dimethyl ester is particularly preferable.

In the present invention, the esterification or transesterification reaction can be carried out by a conventionally known method. That is, terephthalic acid or its ester-forming derivative and 1,4-butanediol are esterified or transesterified at 180 ° C. to 240 ° C. in the presence of a catalyst in the presence of excess diol component to form a low polymer.
Here, transesterification and esterification reaction are carried out under normal pressure, reduced pressure,
Any of pressurization can be performed.

As a catalyst for transesterification or esterification reaction and polycondensation reaction, conventionally known catalysts can be used. Typical examples include titanium compounds and tin compounds, such as tetraalkyl titanates, reaction products of tetraalkyl titanates and alkylene glycols,
Partial hydrolysates of tetraalkyl titanates, titanium hexaalkoxide metal salts, titanium carboxylates, titanium compounds such as titanyl compounds, and further dialkyltin oxides, dialkyltin sulfides, monoalkylhydroxytin oxides, trialkyltin hydroxides. , Tin compounds such as triaryltin hydroxide, and mixtures thereof. Further, the raw materials may be charged all at once, or either one or both may be added stepwise.

The transesterification or esterification and polycondensation may be carried out in a batch system or in a continuous system. Further, solid phase polymerization may be further performed after the melt polycondensation. For such melt polymerization or solid phase polymerization after the addition of poly (alkylene oxide) glycol, a conventionally known method can be adopted.

Further, other copolymerization components such as isophthalic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid and diphenyl-dicarboxylic acid can be used as long as the object of the present invention is not impaired.
4,4'-dicarboxylic acid, bis (4-carboxyphenyl) methane, diphenyl ether-4,4'-dicarboxylic acid, bis (4-carboxyphenoxy) ethane, ethylene bis-p-benzoic acid, 1,4-cyclohexanedicarboxylic acid Acid, 1,3-cyclohexanedicarboxylic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, eicosane diacid, dimer acid, etc., and ethylene glycol, 1,2-propanediol, 1,3-propane as a diol component. Diol, 1,3-butanediol, 1,4-butenediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, diethylene glycol, 1,4-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexane dimethano Le, 2,2-bis (p- hydroxyphenyl) alkylene oxide adducts of propane,
An alkylene oxide adduct of di (p-hydroxyphenyl) sulfone may be added. Further, a small amount of ester-forming polyfunctional component, for example, trimellitic acid, trimesic acid, pyromellitic acid, trimethylolpropane,
You may use pentaerythritol etc.

Furthermore, in the present invention, stabilizers such as hindered phenol compounds and phosphorus compounds are added prior to the start of esterification or transesterification reaction in order to stabilize the process and prevent thermal deterioration and coloration of the polymer. It is preferable to add it at any stage until the end of the condensation. Examples of the hindered phenol compound include triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,
6-hexanediol-bis [3- (3,5-di-t-
Butyl-4-hydroxyphenyl) propionate],
Pentaerythrityl-tetrakis [3- (3,5-di-
t-butyl-4-hydroxyphenyl) propionate], 2,2-thio-diethylenebis [3- (3,5-
Di-t-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 3,5-
Di-t-butyl-4-hydroxybenzylphosphonate diethyl ester, 1,3,5-trimethyl-2,
4,6-Tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, bis (3-t-butyl-6-
Methyl-4-hydroxyphenyl) propane, tris (3-t-butyl-6-methyl-4-hydroxyphenyl) propane, N, N′-hexamethylenebis (3,5
-Di-t-butyl-4-hydroxy-hydrocinnamamide), N, N'-trimethylene bis (3,5-di-t-
Butyl-4-hydroxy-hydrocinnamide) and the like. As the phosphorus compound, for example, phosphoric acid, phosphorous acid, hypophosphorous acid, alkali metal salts thereof,
Examples thereof include alkaline earth metal salts, ammonium salts, alkyl esters and aryl esters thereof. The amount of the stabilizer added is 0.005 to the polymer.
0.5% by weight is preferred.

Further, various additives and modifiers can be added to the polymer of the present invention depending on the application. Examples thereof include pigments, ultraviolet absorbers, terminal blocking agents, thickeners, antistatic agents, crystallization accelerators, reinforcing materials, release agents, flame retardants, plasticizers and the like.

[0017]

The present invention will be described in more detail based on the following examples. In addition, "part" which shows the addition amount in an Example means a weight part. The polymer intrinsic viscosity [η] and the resin physical properties in the examples were measured by the following methods. The polymer intrinsic viscosity [η] was measured at 25 ° C in orthochlorophenol. Tensile yield strength, tensile elongation at break, and Izod impact strength were measured using a fully dried polymer using a screw injection molding machine with a diameter of 3 ounces, a cylinder temperature of 260 ° C, a mold temperature of 40 ° C, and a 3mm thick JIS No. 1 dumbbell test piece. And a 1/8 inch Izod impact test specimen, ASTM D-638 (tensile yield strength,
Tensile elongation at break) and ASTM D-256 (Izod impact strength).

(Example 1) 75.5 parts of terephthalic acid,
61.4 parts of 1,4-butanediol, 0.05 parts of tetra-n-butyl titanate and 0.05 parts of monobutyltin oxide were charged into an esterification reaction can equipped with a rectification column and a stirrer, and heated from 160 ° C to 230 ° C. The reaction was carried out while gradually raising the temperature to 0 ° C., and the produced water and THF were distilled off through a rectification column. After the completion of the esterification reaction, the esterification reaction product was transferred from the esterification reaction can to a polycondensation reaction can, and further 0.07 parts of tetra-n-butyl titanate as a polycondensation catalyst and a hinder as a stabilizer in the product. Dephenol-based compound "Irganox" 1010 (registered trademark,
(Manufactured by Nippon Ciba Geigy) 0.10 part and phosphoric acid 0.0
2 parts were added. Next, the pressure was gradually reduced from normal pressure, and at the same time, the temperature inside the polycondensation reaction vessel was gradually raised from 230 ° C to 250 ° C.

When the reduced pressure in the reaction system was 5 torr or less and the intrinsic viscosity [η] of the polymer reached 0.3, 4.0 parts of polytetramethylene glycol having a number average molecular weight of 2000 was maintained while maintaining the reduced pressure state. Added over about 5 minutes. Then, the polycondensation reaction is finally carried out in the reaction system under conditions of 250 ° C. and 1 torr or less, and the reaction is terminated 2 hours and 50 minutes after the start of depressurization to obtain an intrinsic viscosity [η].
A transparent polymer having a toughness of 0.91 and no phase separation was obtained.

The foaming level in the polycondensation reaction was slight, and the maximum polymer volume ratio during the polycondensation reaction was 1.4 times when the static polymer volume was 1. Table 1 shows the results of the polymerization reaction and the physical properties of the obtained polymer. In addition, Table 1
The transparency of the molten polymer is the result determined by visual observation at the end of the reaction. “◯” indicates transparent, and “x” indicates cloudy and opaque.

[0021]

[Table 1] (Examples 2 and 3, Comparative Examples 1 and 2) Number average molecular weight 2000
The esterification reaction and polycondensation reaction were carried out in the same manner as in Example 1 except that the addition timing of the polytetramethylene glycol was changed as shown in Table 1. The results of the polymerization reaction and the physical properties of the obtained polymer are also shown in Table 1.

When the addition timing of polytetramethylene glycol or the intrinsic viscosity of the polymer is out of the range specified by the method of the present invention, the polymer liquid level rises greatly due to foaming during the polycondensation reaction, and the polycondensation reaction time is also increased. Becomes longer,
The obtained polymer is also phase-separated and opaque, and the polymer has poor physical properties.

Comparative Example 3 The esterification reaction and polycondensation reaction were carried out in the same manner as in Example 1 except that polytetramethylene glycol was not added. The results of the polymerization reaction and the physical properties of the obtained polymer are also shown in Table 1.

Comparative Example 4 The esterification reaction and polycondensation reaction were performed in the same manner as in Example 1 except that polytetramethylene glycol having a number average molecular weight of 2000 was added to the esterification reaction vessel before the start of the esterification reaction. The esterification reaction proceeded, and in the latter half of the reaction, a foaming phenomenon occurred violently in the reaction system, and finally the reaction liquid containing fine bubbles rose to the inside of the rectification column, so that the reaction had to be stopped.

[0025]

Industrial Applicability According to the present invention, industrial production of poly (alkylene oxide) glycol small amount copolymerized polybutylene terephthalate has become possible for the first time. The present invention is particularly applicable to copolymerized PBT from terephthalic acid and 1,4-butanediol.
Is particularly useful when applied to the so-called direct weight method.

Even more surprisingly, molded articles made from the modified PBT obtained in the present invention have higher impact resistance than the prior art, which does not limit the timing of addition of poly (alkylene oxide) glycol. In addition, it has heat resistance and rigidity as an engineering plastic, and has good toughness and impact resistance while maintaining good fluidity. Therefore the connector,
It is useful for injection molded products such as relays, switches, automobile parts such as various cases and housings, electric / electronic parts, and automobile exterior parts.

Claims (2)

[Claims] 1. A bis (hydroxybutyl) terephthalate and / or low polymer thereof is formed by esterification or transesterification of terephthalic acid or its ester-forming derivative with 1,4-butanediol, and polycondensation reaction under reduced pressure. When a polybutylene terephthalate copolymer is produced by reacting poly (alkylene oxide) glycol as a copolymerization monomer while carrying out the reaction, after the reaction pressure reaches 20 torr in the polycondensation reaction, the intrinsic viscosity [η] of the polymer is 0. Polybutylene terephthalate copolymerization, characterized in that 0.1 to 10% by weight of poly (alkylene oxide) glycol is added to the polymer under reduced pressure at any time before reaching 70.70, followed by polycondensation. Manufacturing method of coalescence. 2. A stabilizer comprising a hindered phenolic compound and / or a phosphorus compound is added in an amount of 0.005 to 0.5% by weight based on the polymer at any stage from the start of the esterification or transesterification reaction to the end of the polycondensation. The method for producing a polybutylene terephthalate copolymer according to claim 1, wherein the polybutylene terephthalate copolymer is added.