JPH0764971B2 - Polyethylene terephthalate resin composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a polyethylene terephthalate resin composition, and more particularly to a polyethylene terephthalate resin composition having a remarkably improved crystallization rate.

[Conventional technology]

Polyethylene terephthalate is a resin having excellent properties such as mechanical properties. Most of these performances are derived from the fact that this resin is a crystalline polymer. This resin is produced in large quantities for fibers and films, which is a good example of exactly how the requirements of this field meet their performance. However, on the other hand, it has been pointed out that the crystallization rate is slow, which slows the development in the field of injection molding materials.

Nonetheless, the original performance of this resin is still a great attraction as an injection molding material, and there are great expectations in the market for improvements that are more adaptable to injection molding. Under such a background, many attempts have been made to improve the crystallization property. For example, JP-A-61-157556 discloses a linear saturated polyester with a sodium salt of salicylic acid represented by the following formula. A resin composition containing 0.05 to 2.0% by weight of a potassium salt is proposed.

This crystallization accelerator has an excellent crystallization accelerating effect, but the viscosity of the linear saturated polyester is reduced (the molecular weight is reduced), foaming is likely to occur, and the mechanical strength of the obtained molded article is reduced. .

In particular, it is not suitable for use in small and thin molded products.

[Object of the Invention]

An object of the present invention is to provide a polyethylene terephthalate resin composition which solves the above drawbacks and enables highly crystalline thin-wall molding.

That is, it has been found that such an object can be achieved by blending a specific amount of para-form sodium oxybenzoic acid salt as a crystallinity promoter with a polyethylene terephthalate resin, and has reached the present invention.

[Structure of Invention]

The present invention, for polyethylene terephthalate resin,
The present invention provides a polyethylene terephthalate resin composition containing a compound represented by the following formula in an amount of 0.1 to 3% by weight.

The polyethylene terephthalate resin used in the present invention refers to a linear polyethylene terephthalate having ethylene terephthalate as a constitutional unit, but in some cases, a copolymer of some dicarboxylic acid or diol or a known polyester other than the ethylene terephthalate skeleton. May coexist. At this time, the intrinsic viscosity [η] of the resin and the composition is preferably in the range of 0.45 to 0.9 dl / g. The term [η] used here means phenol /
It can be determined from the viscosity of a solution measured at 30 ° C. in a solvent of tetrachloroethane = 50/50 (weight ratio). If [η] is out of this range, the resulting polyethylene terephthalate resin is not preferable, because the mechanical properties of the resulting polyethylene terephthalate resin will be greatly reduced or the flow processability will be impaired, which will hinder the molding processability.

The amount of the para-form oxybenzoic acid crystallization accelerator used is 0.1 to 3% by weight based on the polyethylene terephthalate resin,
It is preferably 0.5 to 2.5% by weight. If the amount added is outside this range, the effect as a crystallization accelerator cannot be expected, or there is a possibility that a deterioration phenomenon that is undesirable in terms of mechanical properties such as a decrease in the molecular weight of the resin may occur.

The crystallization accelerator of the present invention is sufficiently effective by itself, but further known plasticizers such as ester compounds, ether ester compounds, sulfonamide compounds, etc. or fine particle talc, mica, clay, silica The effect can be further enhanced by using a silicate compound such as

Further, a reinforcing agent such as glass fiber, glass beads, wollastonite, and whiskers may be added for the purpose of enhancing practical performance. In particular, the mechanical properties can be remarkably enhanced by adding 5 to 50% by weight of glass fiber to the whole composition. Also, in that case, flame retardation that is usually performed by those skilled in the art,
Known additives for stabilizing heat resistance and weather resistance may be added.

〔Example〕

 Hereinafter, the present invention will be described more specifically according to examples.

58 g of 95% pure caustic soda pellets are dissolved in 345 g of demineralized water to prepare an aqueous solution of caustic soda, and then 100 g of 95% pure para-hydroxybenzoic acid is added and dissolved. When the solution is cooled to about room temperature and about 10 times volume of acetone is added, the target disodium salt is precipitated. This was separated by filtration, and further, with acetone / water = 9/1 (volume ratio) solution 500 ml, 2
Wash twice.

The disodium salt thus obtained is heated in a hot air drier
After drying at ℃ for 1 day, it was further dried under reduced pressure at 280 ° C, 0.5 Torr for 4 hours.

Examples 1 to 5 Comparative Examples 1 to 5 [η] having a composition shown in Table 1 with the compound synthesized in the polyethylene terephthalate homopolymer of 0.66 according to the reference example and the crystallization accelerator shown in Table 1 With each additive, and Irganox 1010 (manufactured by Ciba Geigy,
0.3% by weight of the product name) is mixed, and the resulting mixture is kneaded by a vent type twin-direction twin-screw extruder (PCM30L / D = 25 manufactured by Ikegai Tekko Co., Ltd.) (cylinder temperature 220 ° C to 280 ° C) and pelletized. The pellets are then injected into an injection molding machine (J 28 manufactured by Japan Steel Works).
Injection molding with SA 0.8 oz), 60mm × 60mm × 1m
A flat plate of m thickness was obtained. (Cylinder temperature 280 ℃ injection / cooling cy
cle 15sec × 15sec, mold surface temperature 80 ℃).

The diagonal line crossing portion was cut out from the flat plate obtained as described above, and the crystallization property was examined by a differential calorimeter (DSCV1.1C Dupont 9900). Note that Tcc in Table-1 is from room temperature to 300 ° C.
It is the crystallization peak temperature that appears when the temperature is raised at 16 ° C / min, and Tc is the crystallization peak temperature that appears when the temperature is lowered at 16 ° C / min after holding at 300 ° C for 5 minutes. . Further
Dc is the ratio ΔH _Tcc / ΔH _Tc of the calorific value ΔH _Tcc due to crystallization at _rising temperature and the calorific value ΔH _Tc due to crystallization at _decreasing temperature to 1
The value obtained by subtracting (1-ΔH _Tcc / ΔH _Tc ) is shown. The closer this value is to 1, the more the crystallization at the time of molding progressed, which is an index for improving the crystallinity.

Further, regarding the molded articles of Example 1 and Comparative Example 5, the Izod impact strength (notched) was determined according to ASTM D256, the flexural modulus and the flexural strength were determined according to ASTM D790, and the tensile elongation ASTM was determined.
Measured according to D638.

The results are shown in Table-1.

[Effects of the Invention] As described above, according to the present invention, it is possible to obtain a polyethylene terephthalate-based resin composition having a small decrease in viscosity (a decrease in molecular weight) and an improved crystallization property.

Continuation of front page (72) Inventor Isao Ikuhara 1000 Kamoshida-cho, Midori-ku, Yokohama-shi, Kanagawa Sanryoseikagyo Co., Ltd. (56) Reference JP-A-61-157556 (JP, A)

Claims (1)

[Claims] 1. A polyethylene terephthalate resin composition comprising a polyethylene terephthalate resin and a compound represented by the following formula in a proportion of 0.1 to 3% by weight.