JPS61241316A - Production of polyester of high polymerization degree - Google Patents

Abstract

PURPOSE:Before it reaches a specific value of its intrinsic viscosity, a polyester is mixed with a polymer which is fluid at the polymerization temperature anc incompatible with the polyester and the polymerization is continued to give a polyester of high polymerization degree as the thermal decomposition is inhibited. CONSTITUTION:(A) An aromatic dicarboxylic acid or its derivative such as terephthalic acid and (B) a diol selected from aliphatic diols or their derivatives and alicyclic diols or their derivatives such as ethylene glycol are polymerized. Before the intrinsic viscosity of the resultant polymer reaches 0.7, a polymer or copolymer which is incompatible with the polyester, e.g., less than 9.5 solubil ity parameter and forms stable fluid of 10-10,000 poise at the polymerization temperature is added to the polyester at a weight ratio of 10-500 to 100 of the polyester and the polymerization is continued to give the objective polyester. The polymer mixed can be removed with a solvent before or after fabrication.

Description

Detailed Description of the Invention (ω) Field of Industrial Application The present invention relates to a method for producing a high molecular weight polyester. More specifically, it relates to a method for producing a high molecular weight polyester by melt polymerizing a polyester in the presence of another polymer.

+b+ Prior Art It is well known that polyesters, typified by polyethylene terephthalate, are used as materials for manufacturing fibers, films, and other molded products.

Molecular weight is a major factor that affects the physical properties such as strength of these molded products, and higher molecular weight is desired in order to improve these physical properties.

However, the deglycol-type polycondensation reaction that is usually carried out is (1) an equilibrium reaction, so the molecular weight can only be increased to a molecular weight corresponding to the glycol partial pressure, and (2) the high-temperature polycondensation reaction causes a decomposition reaction. It has been difficult to obtain high molecular weight polyesters by melt polymerization.

In order to solve these problems, a solid phase polymerization method in which a polymerization reaction is carried out at a low temperature is generally used. However, the solid phase polymerization method has problems such as the reaction takes a long time and the resulting polymer is difficult to dissolve, and the intrinsic viscosity of the resulting polymer is only about 1.4 at most. .

In addition, various studies have been made to improve the melt polymerization method to produce high molecular weight polyesters, and a typical example involves the use of a chain extender. However, this method not only requires an expensive chain extender, but also the parts connected by the chain extender may be thermally unstable, or compounds produced by-products from the chain extender may remain in the polymer, or may cause side-effects. This has the disadvantage that it mixes into the ethylene glycol produced, making recovery of the ethylene glycol difficult.

(C) Object of the Invention An object of the present invention is to provide a method for easily producing high molecular weight polyester by melt polymerization.

Means for Solving the Problem The present inventors have conducted repeated studies to find a method for obtaining high molecular weight polyester using a melt polymerization method. The inventors have discovered that a high molecular weight polyester can be obtained in a short time by carrying out a melt polymerization reaction of polyester in the presence of polyester, leading to the present invention.

(111) Constitution of the Invention The present invention provides at least one aromatic dicarboxylic acid or its ester-forming derivative and an aliphatic diol.

When producing a high degree of polymerization polyester having an intrinsic viscosity of 0.7 or more and consisting of at least one diol compound selected from alicyclic diols and their ester-forming derivatives by a melt polymerization method, the intrinsic viscosity of the polyester is at least 0.7. The subsequent polymerization reaction is carried out in a state in which 10 to 500 parts by weight of a polymer that is incompatible with the polyester, substantially stable, and fluid at the polymerization temperature of the polyester is mixed per 100 parts by weight of the polyester. This is a method for producing a high degree of polymerization polyester.

The polyester targeted in the present invention has aromatic dicarboxylic acid as the main acid component, and aliphatic glycol and/or
Alternatively, the main grilluric component is an alicyclic diol. Here, "mainly" means more than 50 mol%. Therefore, it may contain less than 50 mol% of other components.

In the present invention, aromatic dicarboxylic acids include terephthalic acid,
Isophthalic acid, naphthalene dicarboxylic acid.

These are compounds in which a carboxylic acid is directly bonded to an aromatic nucleus such as diphenyl dicarboxylic acid and diphenyl ether dicarboxylic acid, and terephthalic acid is particularly preferred. In the present invention, aliphatic glycol refers to ethylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, neopentyl glycol, etc. Among these, ethylene glycol, tetramethylene glycol,
Hexamethylene glycol is preferably used.

Further, as the alicyclic diol, cyclohexane dimetatool is preferable.

The third component that can be copolymerized in the present invention includes aromatic dicarboxylic acids other than the main constituent components of polyester; aliphatic dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, adipic acid, sebacic acid, and decanedicarboxylic acid; Alicyclic dicarboxylic acids such as hexahydroterephthalic acid, decalindicarboxylic acid, tetralindicarboxylic acid; glycolic acid, p
- Hydroxycarboxylic acids such as oxybenzoic acid; aliphatic diols other than the main constituents of polyesters such as ethylene glycol, trimethylene glycol, propylene glycol, 1.3-butanediol, neopentyl glycol;
Alicyclic diols such as cyclohexane dimethylol and tricyclodecane dimethylol; bisphenol A, bisphenol S, bishydroxyethoxybisphenol A
, aromatic diols such as tetrapropylene, bisphenol A, and the like.

Such a polyester is prepared by heating an aromatic dicarboxylic acid and/or its lower alkyl ester and a diol in the presence or absence of a catalyst to remove water and/or alcohol. It is produced by performing a so-called esterification reaction and/or transesterification reaction to form a low polymer, followed by polycondensation by heating to a temperature above the melting point under reduced pressure in the presence of a polymerization catalyst to remove the diol. .

In the present invention, it is necessary to coexist with a polymer that is incompatible with the polyester, is substantially stable, and is fluid at the polymerization temperature of the polyester, at least in the stage where the intrinsic viscosity is 0.1 or higher in the polymerization reaction. . Such coexisting polymers preferably have a solubility index (strubility parameter) of 9.5 or less, and for example, olefinically unsaturated hydrocarbons such as ethylene, propylene, styrene, etc. alone or copolymerized are preferably used. These polymers have a melt viscosity of 10 to 10 at a shear rate of 1000/sec at the polyester polymerization temperature.
10,000 poise is preferable, 30-3, Go
Those with o poise are particularly preferably used.

Among them, those having a poise of 50 to 500 poise are particularly preferred.

If the viscosity is higher than this, the effect on polymerization of polyester will be small, and if the viscosity is lower than this, it will be difficult to mix uniformly and it will be difficult to achieve a high degree of polymerization.

The amount of these polymers used is 10% of the resulting polyester.
10 to 500 parts by weight per 0 parts by weight, preferably 20 to 4 parts by weight
00 parts by weight. In particular, this lower limit varies depending on the type of polymer used, viscosity, etc., and it is preferable that the polyester be dispersed in the polymer. Whether this is dispersed or not can be determined by whether or not powdered or fibrous polyester remains when the polymer is extracted and removed from the mixture using a solvent for the polymer that does not dissolve or decompose the polyester. can.

The polymer may be added at any time before the intrinsic viscosity of the polyester reaches 0.7.

It is not known why a high molecular weight polyester can be easily obtained by adding such a polymer, but it may be because glycol is easily eliminated.

Conditions and catalysts for the polymerization reaction in the present invention can generally be those for melt polymerization of polyester, but in particular, in order to suppress thermal decomposition, the conditions and catalysts are close to the melting point, e.g.
It is preferred to carry out the process at relatively low temperatures, such as melting point +20°C. Also, at this time, a titanium compound with low temperature activity,
It is more preferable to use a tin compound.

Furthermore, the method of the present invention can be carried out using the same apparatus as has conventionally been used for performing melt polymerization reactions of polyester.

Although the mixture thus obtained can be molded and used as it is, it is generally used as a polyester after removing the polymer. This polymer may be removed at any time before or after molding, depending on the purpose.

In other words, when the polyester after removal is filamentous (depending on the composition, type of polymer used, viscosity, etc.), it is preferable to remove it after molding if the filamentous form is to be used, but in other cases it is removed before molding. It is normal to do so. Removal of this polymer is generally accomplished by solvent extraction. This solvent may be any solvent that dissolves the polyester or the polymer, and high-boiling hydrocarbons such as xylene, decahydronaphthalene, and tetrahydronaphthalene are often used. Polyester obtained by solvent extraction can be used for various purposes by melt molding or molding as a solution.

Example 1 35 parts of dimethyl terephthalate, 2 parts of ethylene glycol
0 parts, calcium acetate monohydrate 0,022 parts at an internal temperature of 24
After carrying out the transesterification reaction until the temperature reached 0°C, phosphorus @ 5
0.024 parts of 0% aqueous solution and 65 parts of polyethylene (melt viscosity at 265°C 160 poise) were added, and after stirring for 10 minutes, 0.025 parts of titanium tetrabutoxide was added,
React at 265℃ while gradually reducing the pressure until the final degree of pressure reduction is 7.
The reaction was carried out at 0 pa for 3 hours.

The intrinsic viscosity of the powdered polyester remaining after the reaction product was extracted with xylene was measured at 25° C. in orthochlorophenol and found to be 1.62.

Example 2 In Example 1, polystyrene (
A polyester having an intrinsic viscosity of 1.59.1lli was obtained in the same manner as in Example 1, except that 15 parts (melt viscosity at 265°C of 320 poise) were added and the reaction time was changed to 2 hours.

Comparative Example 1 As a result of polymerizing in Example 1 without adding polyethylene, only polyester with an intrinsic viscosity of 0.98 was obtained.

Example 3 44 parts of 2.6 naphthalene dicarboxylic acid methyl ester,
20 parts of ethylene glycol, 0 parts of calcium acetate monohydrate,
50% phosphorous acid after transesterification of 022 parts
0.024 parts of aqueous solution and 0.03 parts of antimony trioxide were added. 285 while distilling ethylene glycol
After raising the temperature to ℃ and reacting for an additional 30 minutes, 10 parts of polypropylene (melt viscosity of 280 voices at 285℃) was added, and the pressure was gradually reduced while stirring, and finally the pressure was reduced to 70 Pa.
The mixture was allowed to react for 3 hours.

After the resulting mixture was extracted with xylene, phenol/
The intrinsic viscosity measured with a tetrachloroethane-6/4 mixture at 25°C was 0.98.

Comparative Example 2 The intrinsic viscosity of Example 3, which was polymerized without adding polypropylene, was 0.69.

Claims (5)

[Claims] (1) A high-density compound with an intrinsic viscosity of 0.7 or more, consisting of at least one aromatic dicarboxylic acid or its ester-forming derivative and at least one diol compound selected from aliphatic diols, alicyclic diols, and their ester-forming derivatives. Degree of polymerization When producing a polyester by a melt polymerization method, the polymerization reaction of the polyester whose intrinsic viscosity is at least 0.7 or higher is carried out using a polyester that is incompatible with the polyester, substantially stable, and fluid at the polymerization temperature of the polyester. 10 to 50 parts by weight of a certain polymer per 100 parts by weight of the polyester.
A method for producing a high polymerization degree polyester, characterized in that the method is carried out in a state in which 0 parts by weight are mixed. (2) The polymer that is incompatible with the polyester, is substantially stable, and is fluid at the polymerization temperature of the polyester has a viscosity of 10 to 10,000 poise at the polymerization temperature of the polyester. A method for producing a high degree of polymerization polyester according to Scope 1. (3) A polymer that is incompatible with polyester, is substantially stable, and has fluidity at the polymerization temperature of the polyester is a polymer obtained by polymerizing at least one monomer selected from ethylene, propylene, and styrene. A method for producing a high degree of polymerization polyester according to claim 1 or 2. (4) Aromatic dicarboxylic acid is terephthalic acid and 2,6-
The method for producing a highly polymerized polyester according to any one of claims 1 to 3, which is at least one selected from naphthalene dicarboxylic acids. (5) Claims 1 to 4 in which the diol compound is ethylene glycol or tetramethylene glycol
A method for producing a high degree of polymerization polyester according to any one of the above items.