JPH0762070A - Fibril-like copolymester and its composition - Google Patents

Abstract

PURPOSE:To provide the copolyester composition rapid in crystallization and excellent in moldability and mechanical characteristics. CONSTITUTION:A optically oriented, fibril-like copolyester having a fibril-like shape and composed from ethylene terephthalate units and para-hydroxybenzoic acid units, and a copolyester composition containing the fibril-like, optically oriented copolyester composed from the ethylene terephthalate units and para- hydroxybenzoic acid units.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a copolyester having both excellent moldability and excellent mechanical properties. More specifically, it relates to a thermoplastic copolymerized polyester resin composition having improved crystallization of a crystalline polyester resin,
Since the polyester resin has high physical properties as well as moldability, it can be applied to molding materials for engineering, films, fibers and the like.

[0002]

2. Description of the Related Art Polyethylene terephthalate (hereinafter PET) containing terephthalic acid and ethylene glycol as constituents
The polyesters represented by () are polymers used in a wide range of fields such as fibers and films. However, it cannot be said that the moldability and mechanical properties are particularly excellent, and there is a demand for a polymer having excellent physical properties. Therefore, it has been proposed to add various fillers for the purpose of improving the crystallinity of the polyester resin, particularly polyethylene terephthalate. In particular, in the case of an inorganic filler such as talc, its crystallinity is improved by its nucleating effect. However, although the effect is somewhat recognized by this method, since the inorganic filler is distributed and dispersed by using a biaxial kneader or the like, a uniform dispersion is not obtained. Further, the strengthening method using glass fiber or the like has problems in uniform dispersibility, moldability and handling.

As a polymer having improved heat resistance and mechanical properties of PET, a liquid crystalline polyester of PET and paraacetoxybenzoic acid by acidolysis reaction has been reported (Journal of Polymer Science: Polym. Chem., Ed,
Vol. 14, 2043 (1976), Japanese Patent Publication No. 56-18016, etc.). These liquid crystalline polymers show improved heat resistance due to the introduction of an aromatic component into the PET structure, and improved mechanical properties due to good melt fluidity and ease of molecular orientation characteristic of liquid crystalline polymers. . However, in liquid crystalline polymers, the ease of molecular orientation appears as anisotropy in the mechanical properties, and the major drawback is that it is strong in the direction of molecular orientation but very weak in the direction perpendicular to it, which results in moldability. Also, the crystallization rate is not particularly excellent.

By the way, it is known that in the copolyester of PET and paraacetoxybenzoic acid, the liquid crystallinity does not show in the case where the blending ratio of paraacetoxybenzoic acid is low. It is expected that it will be a polymer having more excellent heat resistance and mechanical properties than PET, without undergoing the treatment. It has also been reported that foreign substances exhibiting optical anisotropy are present in these polymers. Since this foreign substance has a higher melting point than the original copolymer, it is presumed to be a copolymer having a high proportion of parahydroxybenzoic acid units. In addition, these foreign matters are spherical or dumpling-like under normal conditions, and they may cause a filter to be blocked or a knob in the fiber during spinning for fiberization.Therefore, polymerization conditions for minimizing such foreign matters have been conventionally used. Has been chosen.

[0005]

SUMMARY OF THE INVENTION The present invention aims to overcome the above-mentioned various drawbacks of polyesters and obtain a polyester having both excellent moldability and excellent mechanical properties. The problem to be solved is to control the shape and dispersed state of foreign matter in the copolymerized polyester obtained from PET and para-hydroxybenzoic acid.

[0006]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the inventors of the present invention have earnestly studied and studied, and finally have completed the present invention. That is, the present invention has a fibrillar morphology, and a fibrillar copolyester composed of an optically oriented ethylene terephthalate unit and a para-hydroxybenzoic acid unit, and an ethylene terephthalate unit and a para-hydroxybenzoic acid unit. A copolyester composition comprising a fibrillar, optically oriented copolyester composed of:

In the present invention, the ethylene terephthalate unit is a unit mainly composed of terephthalic acid or its derivative and ethylene glycol.
It may contain a dicarboxylic acid such as 6-dicarboxynaphthalene, 4,4'-dicarboxybiphenyl, isophthalic acid and adipic acid. The para-hydroxybenzoic acid unit is a unit synthesized from para-acetoxybenzoic acid or its derivative. The proportion of each unit is not particularly limited, but it is preferable to carry out at a proportion such that the copolymer does not exhibit melt liquid crystallinity, and ethylene terephthalate unit units are 40 mol% or more and 99 mol% or less, and para-hydroxybenzoic acid. It is a copolyester having an acid unit of 1 mol% or more and 60 mol% or more. The fibril form in the present invention means a length of 1 to 20 μm, a diameter of 0.01 to 1 μ, and an L / D of 10 to 200. Optical orientation means a crystalline state in which molecules are regularly arranged to some extent. Yes, it means that it looks bright in the dark field.

The fibrillar copolyester of the present invention and the composition thereof can be obtained by mixing PET previously synthesized with paraacetoxybenzoic acid, or by polymerizing PET in a polymerization container, and after completion of the reaction, paraacetoxybenzoic acid. Any method such as adding an acid can be adopted. As the PET to be used, it is preferable to use a polymer obtained by a direct polymerization method, a transesterification method or the like and having an intrinsic viscosity of 0.4 or more, preferably 0.6 or more. Paraacetoxybenzoic acid is added while these polyesters are kept in a molten state in a molten state under high shear and in a stirred state. In order to suppress the decomposition of polyester, it is charged in an atmosphere of an inert gas such as nitrogen or carbon dioxide. When the polyester is PET, the reaction is carried out at 260 to 300 ° C., and the reaction time is about 30 to 120 minutes. After the completion of the reaction, the pressure is gradually reduced to carry out the polymerization, but it is necessary to select the reaction conditions according to the ratio of paraacetoxybenzoic acid. It is desirable to carry out acid decomposition and polymerization at a lower temperature as the proportion of paraacetoxybenzoic acid is higher, and for example, 220 mol.
For 95 mol% PET and 5 mol% paraacetoxybenzoic acid, the temperature is set to 240 to 270 ° C. The atmosphere is not particularly limited, but it is performed under reduced pressure and pressure under an inert gas atmosphere. Regarding the polymerization conditions, the temperature is lowered according to the ratio of PET and paraacetoxybenzoic acid, and the polymerization is carried out under high vacuum. It is preferable to polymerize at a temperature as low as possible.

When obtaining the copolyester of the present invention,
For example, in a copolymerization method using acid decomposition of PET and paraacetoxybenzoic acid, a catalyst such as a zinc compound, an antimony compound, a manganese compound is used, or solid phase polymerization of a polymer is performed following melt polymerization under reduced pressure. Or by using both of them together, a polymer having a desired degree of polymerization can be obtained.

By the above-mentioned method, the copolyester composition of the present invention having a fibril phase in the system can be obtained. As a method for isolating the fibrillar copolyester, for example, a parachlorophenol / tetrachloroethane mixed catalyst is used. It can be isolated by solubilizing in water, filtering with a membrane filter, washing and drying. The isolated fibrillar copolyester of the present invention can also be used as a reinforcing material in itself, and other thermoplastic polymers such as polyamides,
You may mix | blend with polyester, polyolefin, polyphenylene sulfide, polyphenylene ether, etc.

[0011]

The reason for the high crystallinity of the copolyester composition of the present invention is that the reaction between PET and para-acetoxybenzoic acid and the polymerization conditions of the copolyester are selected so that a large amount of foreign matter, which was conventionally in an irregular form, is generated. Moreover, by forming a uniform fibril form, it is possible to improve the crystallinity and obtain a polyester copolymer having both excellent moldability and excellent mechanical properties. The improvement of crystallinity is mainly due to the fact that the fibril phase formed in the system has already been molecularly oriented to some extent, which promotes the orientation fluctuation during the crystallization of PET, and consequently affects the induction time. it is conceivable that.

[0012]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples. The method for evaluating polymer properties was as follows. The melt viscosity was measured by dissolving the polymer at a concentration of 0.4 g / dl in a parachlorophenol / 1,1,2,2-tetrachloroethane = 3/1 mixed solution and measuring the reduced viscosity at 30 ° C. The fibrils in the polymer were judged by the fact that the polymer in the molten state was rapidly cooled and showed birefringence when observed under a microscope under deflection. The crystallinity of the polymer was indicated by the difference between the crystallization temperature and the melting point when the temperature of the molten polymer was lowered at 10 ° C./min in an argon atmosphere using a differential scanning calorimeter (Shimadzu TA-50). The smaller the difference, the better the crystallinity. The tensile strength and Izod impact strength of the molded body are AS
It measured based on TM-D638 and D256.

Example 1 467 g of polyethylene terephthalate (intrinsic viscosity 0.6) containing 0.05 mol% of zinc acetate (based on terephthalic acid) was polymerized by a conventional method. While maintaining the temperature at 270 ° C. and stirring under high shear, 49 g of paraacetoxybenzoic acid was added little by little under a nitrogen atmosphere. (The content of para-acetoxybenzoic acid is 10 mol% with respect to PET), after reacting for 40 minutes at the same temperature, the pressure is gradually reduced to 0.2 to 0.3 mmHg, and at the same time, the temperature is lowered to 260 ° C. Polymerization was carried out for 4 hours. The reduced viscosity of the obtained polymer is 0.63.
Met. The fibril state is shown in Photo 1 and the polymer properties are shown in Table 1.

Example 2 A copolymer was synthesized in the same manner as in Example 1 except that the ratio of PET to the amount of paraacetoxybenzoic acid was 68/32, the reaction temperature was 270 ° C., and the polymerization temperature was 260 ° C. The fibril state of the obtained polymer is shown in Photo 2.
The characteristics are also shown in Table 1.

Comparative Examples 1 and 2 All the same as Example 1 except that only PET used in Example 1 was used as Comparative Example 1 and PET was kept at 280 ° C. and stirred without much shear. The polymer obtained in the above is referred to as Comparative Example 2, and the respective characteristic values are also shown in Table 1.

[0016]

[Table 1] In Table 1, ABA: Paraacetoxybenzoic acid PET: Polyethylene terephthalate

[0017]

EFFECT OF THE INVENTION Since the copolyester composition of the present invention having the above-mentioned constitution uniformly disperses the fibrillar copolyester of the present invention exhibiting optical orientation, as is clear from Table 1, It has better moldability than PET,
It is possible to obtain a molded product having good crystallinity and having few defects due to anisotropy of mechanical properties. Therefore, it can be widely applied as an engineering plastic required to have high physical properties and contributes to the industrial world.

Claims (2)

[Claims] 1. A fibrillar copolyester comprising a fibrillar morphology and optically oriented ethylene terephthalate units and parahydroxybenzoic acid units. 2. A copolymerized polyester composition comprising a copolymerized polyester composed of an ethylene terephthalate unit and a parahydroxybenzoic acid unit and containing a fibrillated and optically oriented copolymerized polyester.