JPS62250028A - Novel polyester and production thereof - Google Patents

Abstract

PURPOSE:To obtain a novel polyester, having improved mechanical strength and high flexibility and suitable for magnetic tapes, etc., by reacting polyethylene terephthalate with a specific acyloxy aromatic carboxylic acid and a very small amount of a trifunctional compound. CONSTITUTION:A polyester, obtained by blending and reacting (A) terephthalic acid (dimethyl ester) and ethylene glycol forming constituent units expressed by formula I with (B) an acyloxy aromatic carboxylic acid forming constituent units expressed by formula II, e.g. m-acetoxybenzoic acid, etc., and (C) a trifunctional compound forming constituent units expressed by formula III, e.g. 1,3,5-triacyloxybenzene, etc., at preferably 0.25-1.5mol ratio A/B of constituent units and 0.0005-0.01mol ratio [C/(A+C)] of constituent units, e.g. at 200-350 deg.C, and having >=0.2dl/g reduced viscosity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a novel polyester and a method for producing the same. More specifically, the present invention has excellent mechanical strength and flexibility, and is suitable for materials such as magnetic tapes and floppy disks, and optical fiber reinforcing materials, and has high knot strength in filaments, etc. This article relates to a new polyester with excellent features such as, and its manufacturing method.

[Conventional technology]

Polyethylene terephthalate is a thermoplastic resin with a chain structure obtained from terephthalic acid or its dimethyl ester and ethylene glycol, and has high tensile strength, bending strength,
Because it has excellent mechanical strength such as compressive strength, abrasion resistance, electrical insulation, and heat resistance, it is used in various fields such as films and fibers, and it is also blended with glass fiber. is widely used as a thermoplastic molding material for electrical and mechanical parts.

As a method for further improving the mechanical strength of such polyethylene terephthalate, a method has been proposed in which, for example, polyethylene terephthalate is reacted with an acyloxy aromatic carboxylic acid (Japanese Unexamined Patent Publication No. 72393/1983). In this method, a raw material polyester and an acyloxy aromatic carboxylic acid are first heated at a required temperature under normal pressure to acidolyse the polyester to obtain polyester fragments, and then the fragments are heated under reduced pressure at a required temperature. In this method, the desired copolymerized polyester is produced by heating the polyester to increase its intrinsic viscosity.

However, when the polyester obtained by the above method is extruded, although it shows excellent strength in the extrusion direction of the molded product, the strength in the direction perpendicular to the extrusion direction is not sufficient, and as a result, nodules, which are satisfactory in filaments, etc. It has the disadvantage of not being strong enough.

[Problem that the invention seeks to solve]

The present invention improves the drawbacks of the conventional polyester obtained by reacting polyethylene terephthalate and acyloxy aromatic carboxylic acid, and has excellent mechanical strength and good balance, and is suitable for use in filaments, etc. The object of the present invention is to provide a new polyester that not only has excellent knot strength but also has flexibility.

[Means for solving problems]

As a result of extensive research to achieve the above object, the present inventors have found that polyethylene terephthalate is reacted with a specific acyloxy aromatic carboxylic acid and a trace amount of a certain trifunctional compound, and the resulting polyester is branched. It was discovered that the objective could be achieved by introducing a small amount of ester structural unit, and based on this knowledge, the present invention was completed.

That is, the novel polyester of the present invention has a structural unit represented by the formula % formula % ( ) +00CO + (B ) and back 0 → -, and has a composition of 0.2 g/dJt 1 degree using p-chlorophenol as a solvent. The reduced viscosity of the solution at 60°C is 0.2d7! /g or more.

The thus obtained polyester of the present invention is a novel product having the above-mentioned structural units (A), (B), and (C), each of which is bonded via an ester bond. The molar ratio of structural unit (A)/constituent unit (B) is preferably 0°25 to 1.5, and the molar ratio of structural unit (C)/
[Constituent unit (' A) 10 constituent units (C)
) is preferably 0.0005 to 0.01. If the molar ratio of the structural unit (A) to the structural unit (B) is less than 0.25, flexibility will be lost;
If it exceeds 5, the improvement in mechanical strength will be insufficient. Furthermore, if the molar ratio of the structural unit (C) to the sum of the structural units (A) and (B) is less than 0.0005, the mechanical strength will be unbalanced and sufficient nodule strength will not be obtained. On the other hand, if it exceeds 0.01, the flexibility deteriorates.

Also, the reduced viscosity is 0.2d7! If it is less than /g, sufficient mechanical strength and knot strength cannot be obtained.

The novel polyester of the present invention is represented by the following general formula, for example.

(In the formula, x, x', ”, one of which is a constituent unit (A) and the rest is a constituent unit (B),
z, x', l", m, m", and M' are the numbers of respective structural units, and each structural unit is bonded with an ester bond. ) The polyester of the present invention comprises polyethylene terephthalate, acyloxybenzoic acid and the general formula (ill, R in the formula
2 and R3 are each an alkyl group having 1 to 4 carbon atoms, and they may be the same or different from each other). .

The polyethylene terephthalate used in the present invention is a crystalline linear polymer compound having repeating units of
It is obtained by condensation polymerization of terephthalic acid or its dimethyl ester and ethylene glycol. Usually 0.2 g using p-chlorophenol as a solvent
Reduced viscosity (ηs
p/c) is 0.1 to 1. OdIl/g is used, and those in which the dicarboxylic acid component and diol component have been modified to other components can also be used within a range that does not impair the purpose of the present invention.

As the acyloxybenzoic acid, one represented by the general formula R-Coo@C0OH (R is an alkyl group having 1 to 4 carbon atoms) is preferably used. These can generally be produced by reacting p-hydroxybenzoic acid with a carboxylic acid whose alkyl group has 1 to 4 carbon atoms or a reactive derivative thereof, such as an acid anhydride or an acid chloride.

Examples of acyloxybenzoic acids include m-acetoxybenzoic acid, p-acetoxybenzoic acid, 4-acetoxy-3-
Examples include methoxybenzoic acid, 4-acetoxy-3-chlorobenzoic acid, and 4-acetoxy-3,5-dichlorobenzoic acid, and p-acetoxybenzoic acid is preferably used.

Further, the trifunctional compound used in the present invention is a 1.3.5-)lyacyloxybenzene represented by the above general formula, and even if the acyloxy groups are the same, they are different from each other. However, usually the same one is preferably used.

This trifunctional compound can be obtained, for example, by reacting phloroglucin with a carboxylic acid whose alkyl group has 1 to 4 carbon atoms or a reactive derivative thereof, with, for example, an acid anhydride or an acid chloride.

Among the trifunctional compounds, phloroglucin triacetate is preferred, and can be easily obtained, for example, by reacting phloroglucin with acetic anhydride or acetic chloride.

The polyester of the present invention can be obtained by using the above-mentioned polyethylene terephthalate, acyloxybenzoic acid, and trifunctional compound in a predetermined ratio, heating them, and reacting them.

Regarding the usage ratio of each component, it is preferable to use each component so that the ratio of each structural unit in the resulting copolymerized polyester falls within a predetermined range.

The reaction is generally preferably carried out in two stages at a temperature in the range of 200 to 350°C. For example, first, polyethylene terephthalate, acyloxybenzoic acid, and a trifunctional compound are mixed at predetermined ratios, and 200 to 35
The reaction is carried out by heating at a temperature in the range of 0°C, preferably 250 to 320°C. At this time, it is preferable to heat under an inert gas atmosphere such as nitrogen or argon, and although there is no particular restriction on the pressure, the reaction is usually carried out under normal pressure. The reaction time is usually about 0.5 to 5 hours.

In this first stage reaction, most of the acid produced by the acidolysis reaction is distilled out of the system.

Next, the pressure inside the system is reduced, preferably below roomHg,
More preferably 1QwmHg or less, 200 to 35
The reduced viscosity at 60°C of a solution of the copolymerized polyester produced by heating to a temperature in the range of 0°C, preferably 250 to 320°C and having a concentration of 0.2 g/di using p-chlorophenol as a solvent is 0.2 dA. The reaction is continued until it reaches /g or more. This reaction time depends on the temperature and the degree of reduced pressure, but is usually about 0.5 to 5 hours.

The reaction can be carried out without the use of a catalyst, but
Catalysts such as cobalt can also be used to accelerate the polymerization reaction.

The polyester of the present invention is useful for manufacturing molded articles and has sufficient knot strength in filaments.

The polyesters of this invention can be made into useful products using conventional and common methods and equipment. for example,
Can be made into fibers by common melt spinning techniques,
It can also be injection molded and can be formed into a film.

The polyesters of the present invention can also contain fillers, pigments, glass fibers, asbestos fibers, antioxidants, stabilizers, plasticizers, lubricants and other additives.

〔Example〕

Hereinafter, the present invention will be explained in detail based on Examples, but the present invention is not limited thereto.

Example 1 A reactor equipped with a stirring device and an argon gas introduction tube was
7.68 g (40 mmol) of polyethylene terephthalate, 10.8 g (60 mmol) of p-acetoxybenzoic acid, and 0.076 g of phloroglucin triacetate.
(0.3 mmol) at 280°C under an argon stream.
The acetic acid produced was distilled off while stirring for 1 hour. Then, the pressure inside the reactor was reduced to 1 mHg, and the pressure was reduced to 28 mHg.
The reaction was carried out at 0°C for 2 hours. The polymer obtained here is
The reduced viscosity (ηsp/c) at 60°C at a concentration of 0.2 g/dN using p-chlorophenol as a solvent is 0.27.
d7! /g, and as a result of infrared absorption spectrum analysis, absorption due to benzene ring at 1580 cm-' and 1490 cm-', absorption due to carbonyl group at 1650 cm-', and absorption due to ether bond at 1240 cm-' were observed. It was done. Furthermore, it was confirmed that this polymer exhibits liquid crystallinity at 250° C. under a polarizing microscope.

Next, this polymer was extruded at 300° C. through a nozzle with an inner diameter of 1 day to obtain fibers with a thread diameter of 30 μm. The tensile strength, elastic modulus, elongation, and knot strength of the obtained fibers were measured in accordance with JIS-L-1069. The results of these measurements are shown in Table 1.

Example 2 A Use of phloroglucin triacetate 1 0.151 g
Polymer (reduced viscosity [η sp/c) = 0.90 dl was prepared in the same manner as in Example 1 except that (0.6 mmol)
/g) was obtained. This polymer was also spun in the same manner as in Example 1, and the properties of the obtained fibers are shown in Table 1.

Comparative Example 1 A polymer (reduced viscosity [ηsp/c
) = 0.40 d ll/g) was obtained. Table 1 shows the properties of fibers obtained by spinning this polymer.

Margins below [Effects of the Invention] According to the present invention, a novel polyester which has excellent mechanical strength and a good balance thereof, which provides excellent knot strength in filaments and the like and which also has flexibility has been obtained.

Claims (1)

[Claims] 1. Formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (A), Formula ▲
There are mathematical formulas, chemical formulas, tables, etc. ▼ (B) and ▲ Mathematical formulas,
There are chemical formulas, tables, etc.▼0.2 which has the structural unit represented by formula (C) and uses p-chlorophenol as a solvent
The reduced viscosity at 60°C of a solution with a concentration of g/dl is 0.2
A novel polyester characterized by having a dl/g or more. 2. The molar ratio of structural unit (A) / structural unit (B) is 0.2
5 to 1.5, and structural unit (C)/[constituent unit (
A) + structural unit (B)] molar ratio is 0.0005 to 0.
The novel polyester according to claim 1, which is 01. 3. Polyethylene terephthalate, acyloxybenzoic acid and general formula ▲ Numerical formula, chemical formula, table, etc. ▼ (In the formula, R^1, R^2 and R^3 are each an alkyl group having 1 to 4 carbon atoms, and Even if they are the same,
There are formula ▲ mathematical formulas, chemical formulas, tables, etc. ▼ (A), formula ▲ mathematical formulas, chemical formulas, tables, etc., which are characterized by reacting trifunctional compounds represented by ▼(B) and formulas ▲Mathematical formulas, chemical formulas, tables, etc. ▼(C) At 60℃ of a solution with a concentration of 0.2 g/dl that has the structural unit represented by (C) and uses p-chlorophenol as a solvent. A method for producing a novel polyester having a reduced viscosity of 0.2 dl/g or more. 4. Structural unit (A)/structural unit (B) of new polyester
) has a molar ratio of 0.25 to 1.5, and the structural unit (
The method for producing a novel polyester according to claim 3, wherein the molar ratio of C)/[structural unit (A) + structural unit (B)] is 0.0005 to 0.01.