JP2647511B2 - Molding polyester - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a polyester to be used as a molding material, in particular, a polyester excellent in moldability suitable for producing general molded products other than fibers and films.

Conventional technology Conventionally, polyester, especially polyethylene terephthalate, has a high softening point, including chemical resistance, light resistance, heat resistance,
Due to its excellent electrical and physical / mechanical properties, it is widely used as fiber or film. However, it cannot be said that polyethylene terephthalate is sufficiently utilized as an injection molded product or an extrusion molded product.
The reason for this is that although polyethylene terephthalate is a crystalline polymer, the crystallization rate is lower than that of the same crystalline polymer, nylon, polyacetal, etc.
In particular, crystallization hardly progresses at a temperature of 120 ° C. or lower, so that a satisfactory molded product cannot be obtained under ordinary injection molding conditions. Usually, the molding of the thermoplastic resin is carried out 60 to 12
In a mold at a temperature of 0 ° C., crystallization progresses only partially,
The product becomes uneven and the dimensional stability is poor.

For the purpose of solving these drawbacks, an attempt has been made to increase the mold temperature and employ a long holding time by utilizing the fact that the crystallization rate of polyethylene terephthalate is maximized at 160 to 180 ° C. A mold at a temperature of not less than ° C is not common, and the working efficiency is extremely low.

Therefore, its use in injection molding applications requiring high moldability is significantly limited.

Conventionally, various methods have been proposed as methods for accelerating crystallization of polyethylene terephthalate. For example, there is a method of adding a so-called nucleating agent to increase the crystal nucleus generation rate. As a nucleating agent, inorganic solid substances such as talc, metal salts of inorganic and organic acids, metal glycolates and the like are known, and also, ionic copolymers and organic polymer nucleating agents such as high melting point polyethylene terephthalate are used. Use has also been attempted. However, there is a limit in promoting crystallization of polyethylene terephthalate only by adding such a nucleating agent. That is, by adding this kind of nucleating agent, the molding cycle in a high-temperature mold at 140 ° C. or higher can be shortened, but at a mold temperature of 120 ° C. or lower, crystallization still does not sufficiently proceed, so that processing or physical properties It is difficult to obtain a highly stable and highly crystallized molded product. Furthermore, when the nucleating agent is an inorganic solid substance insoluble in polyethylene terephthalate, it is difficult to uniformly disperse the nucleating agent in the polymer, and the nucleating agent effect cannot be sufficiently exhibited. Attempts have also been made to add polyalkylene glycols as a nucleating agent aid together with a nucleating agent such as talc or gypsum.
It has not been able to drop below 0 ° C.

Therefore, the present inventors, in order to improve the crystallinity of polyethylene terephthalate, even in the glassy state, the polyester molecular chain moves to some extent, imparts mobility so that it can be oriented, and causes phase separation with the polyethylene terephthalate component. From the viewpoint that it is effective to introduce a component that does not affect the crystallinity or mechanical strength of the molded product, crystallization is rapid even if the mold temperature during molding is 120 ° C or less. As a result of intensive studies to obtain a molded product having excellent moldability and surface appearance, and excellent mechanical strength and heat resistance, the present invention has been achieved.

On the other hand, many research reports have been made on improving the crystallinity as described above. For example, the general formula HOR
Polyalkylene glycols represented by -O _n H or a method of adding at any point in combination with a nucleating agent polymer synthesis,
There is a method in which the performance of the polyester polymer is improved by copolymerization.

For example Japanese Patent Publication to 47-3026 has the general formula HOR-O _n part of nitrogen R chain R-O _n of H, oxygen, phosphorous, high utilizing a compound obtained by replacing the hydrocarbon organic group containing a sulfur A method for improving the moldability of a polymerization degree polyester is described.

However, even if the mold temperature at the time of molding is 120 ° C. or lower as a polyester for a molding material, crystallization is rapid, and no modification has been made to improve moldability.

The present invention relates to a terephthalic acid or an ester-forming derivative thereof, ethylene glycol or an ester-forming derivative thereof, Is a copolymerized polyester molding material containing 0.1 to 10% by weight of the compound with respect to the copolymer by copolymerizing with a polyester polyol having an average molecular weight of 1,000 to 5,000.

The term “terephthalic acid or an ester-forming derivative thereof” as used in the present invention is an ester-forming derivative such as terephthalic acid or a lower alkyl ester or a phenyl ester thereof.

In the present invention, “ethylene glycol or an ester-forming derivative thereof” is an ester-forming derivative of ethylene glycol such as ethylene glycol or ethylene oxide.

In the present invention, a base polyester comprising the above “terephthalic acid or an ester-forming derivative thereof” and “ethylene glycol or an ester-forming derivative thereof” has the following general formula: Is copolymerized.

N in the formula is a positive integer indicating the degree of polymerization, and is the number of repetitions at which the average molecular weight is in the range of 1,000 to 5,000. Here, when the average molecular weight is less than 1,000, the effect of copolymerization is not exhibited, and when it exceeds 5,000, the reactivity is remarkably reduced, and a preferable copolymer cannot be obtained.

The content (copolymerization amount) of the polyester polyol in the copolymer is 0.1 to 10% by weight, preferably 1 to 5% by weight.

If the amount is less than 0.1% by weight, the effect of improving the crystallization rate is not exhibited. If the amount is more than 10% by weight, the copolymer is compared with the melting point of a homopolymer not copolymerizing the polyester polyol. Greatly decreases the heat resistance of the molded product.

The polyester copolymer is prepared by a known method, for example, a method of subjecting a terephthalic acid component and an ethylene glycol component to melt polycondensation after esterification or ester exchange, before, during, and after the start of the ester exchange or esterification reaction. Thereafter, the polyester polyol can be added during the polycondensation reaction, and the polycondensation reaction can be completed after the addition.

Known nucleating agents, heat stabilizers, light stabilizers, coloring agents, flame retardants, fillers, reinforcing agents, and the like may be added to the copolymer by a method such as a melt blending method. Further, a small amount of another polymer may be mixed.

Further, it is possible to increase the molecular weight by subjecting the copolymer to solid phase polymerization.

The copolymer thus obtained is particularly preferable for injection molding, but it can be molded by extrusion molding or other molding methods.

The molded product obtained by molding the copolymer of the present invention has remarkably excellent crystallization characteristics and moldability as compared with the polyethylene terephthalate single molded product, as is clear from the examples described below, and the mold temperature is 120 ° C. Hereafter, even in a short molding cycle, the releasability and surface appearance are extremely good, and various physical properties such as mechanical strength and heat resistance are stably excellent. Specific examples of molded articles include, for example, automobile parts such as cams,
There are gears, rollers, bearings, etc. and small electronic and electrical components in the television and communication fields such as tuners, switches, relay housings, connectors and the like.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples.

The following parts are all based on weight, and [η] of the copolymer in the examples was obtained from the solution viscosity measured at 35 ° C. in phenol / tetrachloroethane (3: 2 parts by weight). It is.

The measurement of the melting point Tm of the copolymer, the cooling crystallization temperature Tcd, and the heating crystallization temperature Tci was performed by Dupont 910DSC and 990Thermal Anal.
According to yzer. The higher the Tcd temperature and the lower the Tci temperature, the faster the crystallization. Therefore, ΔT = Tcd−T
In the case of ci, the larger the value is, the higher the crystallization rate is, and the higher the crystallization rate is at a mold temperature of 120 ° C. or less, and a polymer having good moldability corresponds to a case where ΔT is 50 ° C. or more. . The heat distortion temperature (4.7 kg / cm ² load) of the molded article was measured by a method according to ASTM-D648.

[Examples 1 and 2 and Comparative Example 1] 100 parts of dimethyl terephthalate, ethylene glycol 60
Parts, 0.08 part of manganese acetate was charged to a transesterification tank and used as a starting material.
06 parts and 0.08 parts of antimony trioxide were added, and the temperature was raised to 240 ° C. while simultaneously removing excess ethylene glycol, and then transferred to a polycondensation reaction tank. In addition, the average molecular weight of 2000 Was added so as to be a copolymer component shown in Table 1, and a polycondensation reaction was carried out by heating and reducing the pressure to obtain a copolymer. The intrinsic viscosity, melting point, cooling crystallization temperature, and heating crystallization temperature of the obtained polymer were measured, and the heat distortion temperature was measured using a test piece molded by injection molding.

[Comparative Example 2] Instead of the compound used as the copolymer component in Example 1, A copolymer was prepared and evaluated in the same manner as in Example 1 except that the compound represented by the following formula (average molecular weight: 2,000) was used.

[Comparative Example 3] Compound used as copolymerization component in Example 1 Average molecular weight of 2000 (n ≒ 8) to 700 (n ≒ 2)
A copolymer was prepared and evaluated in the same manner as in Example 1 except that the copolymer was replaced with the above.

[Comparative Example 4] Compound used as copolymerization component in Example 1 From 2,000 (n ≒ 8) to 6000 (n ≒ 26)
An attempt was made to prepare a copolymer in the same manner as in Example 1 except that the copolymer was replaced with the above. However, the degree of polymerization did not increase as expected, and no molding evaluation was performed.

Comparative Example 5 A polyester comprising dimethyl terephthalate and ethylene glycol was prepared without using the copolymer component used in Example 1.

The analysis and evaluation results of the polymers obtained in Examples 1 and 2 and Comparative Examples 1 to 5 are summarized in Table 1.

Claims (1)

(57) [Claims] A terephthalic acid or an ester-forming derivative thereof, ethylene glycol or an ester-forming derivative thereof, and a compound represented by the general formula: [Where n represents the degree of polymerization, and the average molecular weight of the compound is
It is a positive integer corresponding to 1000-5000. A copolymer obtained by copolymerizing a polyester polyol having an average molecular weight of 1,000 to 5,000, wherein the polyester polyol is contained in an amount of 0.1 to 10% by weight based on the copolymer (total). Polyester for molding.