JPH0364352A - Polyester resin composition - Google Patents

Abstract

PURPOSE:To obtain a polyester resin composition which can be injection-molded at a low temperature and can give a molding excellent in surface appearance and heat resistance by mixing a polyethylene terephthalate resin with a polybutylene terephthalate resin, a specified polyalkylene glycol and a crystallization accelerator. CONSTITUTION:The title composition is obtained by mixing 100 pts.wt. polyethylene terephthalate resin mainly consisting of repeating ethylene terephthalate units with 5-450 pts.wt. polybutylene terephthalate resin, 0.5-8 pts.wt. end-blocked polyalkylene glycol of a weight-average mol.wt. of 500-4000, wherein the hydrogen atom of the hydroxyl of each end is replaced by an alkyl, an aryl or an aralkyl (e.g. polyethylene glycol dimethyl ether) and 0.1-50 pts.wt. crystallization accelerator (e.g. talc or sodium benzoate). This composition can be injection- molded in a mold at a temperature as low as about 80 deg.C and can give a molding excellent in surface appearance and heat resistance.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention is capable of providing a molded article having excellent mechanical properties, thermal properties, and chemical resistance, and a polyester-based product having excellent moldability. The present invention relates to a resin composition.

[Prior art and problems to be solved by the invention] The various properties of molded products obtained from crystalline polymers such as polyethylene terephthalate (hereinafter abbreviated as PET) strongly depend on the degree of crystallinity; When trying to obtain a molded product with heat resistance, a crystal nucleating agent such as a metal salt of an organic carboxylic acid or an inorganic compound is added to the PET resin.
Furthermore, it was necessary to set the mold temperature to a high temperature of 130 to 140°C for molding.

In addition, other methods for obtaining heat-resistant molded products include:
A molded product molded in a low-temperature mold of 100°C or less and still in a partially crystallized state is post-heat-treated to promote crystallization, or the molded product is immersed in a liquid that promotes crystallization. A known method was to promote crystallization through post-processing such as drying to increase heat resistance.

However, obtaining a highly crystallized resin molded product using a method using a high-temperature mold or a post-processing method has drawbacks in terms of work stability and economic efficiency. On top of that,
When such a PET-based resin composition was molded at a low mold temperature of 100° C. or lower, it was difficult for the resin molded product to sufficiently crystallize, resulting in poor mold releasability. Therefore, in order to improve the releasability of the resin molded product from the mold, it is necessary to cool the mold slowly, and cooling takes a long time.

It is known to improve this drawback and use various crystallization accelerators in PET resin as a method for molding at a low mold temperature. For example, in PET, α-olefin and α,
Japanese Patent Publication No. 45-26225 discloses a method of adding an ionic copolymer consisting of a salt of a β-unsaturated carboxylic acid. In addition, a method of using polyalkylene glycol and an inorganic filler such as talc in combination was published in 1973-302.
It is disclosed in Publication No. 7. Furthermore, ionic copolymers,
A combination system of a polyalkylene glycol compound and an inorganic filler is also disclosed in JP-A-59-22958.

Furthermore, methods are known in which the crystallization rate is improved by copolymerizing a soft segment with PET or by using a crystallization promoter in combination. For example, JP-A-60-223850 discloses a method of adding an ionomer and a polyolefin to a copolymer of polyalkylene glycol and PET.

However, when such a resin composition is injection molded using a mold whose temperature can be controlled by an economical hot water circulation type temperature control device, for example, about 80°C,
Although the releasability of the molded product from the mold and the mechanical strength of the resulting molded product were good, the appearance of the molded product was not necessarily satisfactory.

In addition, polybutylene terephthalate (hereinafter referred to as PB) is added to PET.
The method of blending
It is disclosed in Publication No. 32. However, in this case the amount of PET is less than the amount of PBT, e.g.
Unless E T/P B T =30/TO to 20/80 (weight ratio), the molded product obtained by molding at a mold temperature of 80'C did not exhibit a good surface appearance.

Furthermore, even when the amount of PBT is greater than the amount of PET, the molding cycle when molding a molded article from the resin composition is not as satisfactory as the molding cycle when molding from PBT alone. .

On the other hand, the surface gloss of molded products obtained from PBT alone was not good.

[Means for Solving the Problems] In view of the current situation, the present inventors have conducted extensive research, and as a result, have added PBT resin, a specific double-terminated polyalkylene glycol, and a crystallization accelerator to PET resin. By blending in a specific amount, it is possible to obtain a polyester resin composition that has excellent moldability even when molded using a low-temperature mold, and can be made into a molded product having excellent heat resistance and surface appearance. They discovered this and completed the present invention.

That is, in the present invention, for 100 parts by weight of PET resin containing ethylene terephthalate as a main repeating unit,
(B) 5 to 450 parts by weight of PBT resin; (c) a weight average molecule in which the hydrogens of both terminal hydroxyl groups are substituted with an alkyl group, an aryl group, or an aralkyl group;
000 both end-blocked polyalkylene glycol 0.5
~8 parts by weight and (D) 0.1 to 5 parts by weight of crystallization promoter
This is a polyester resin composition containing 0 parts by weight.

(A) PET resin having ethylene terephthalate as a main repeating unit used in the present invention is at least 90%
It is a polymer obtained by subjecting a dicarboxylic acid or its derivative component consisting of terephthalic acid in mol% and an ethylene glycol component of at least 90 mol% to an esterification reaction or transesterification reaction, and then a polycondensation reaction. Examples of terephthalic acid derivatives include dialkyl esters and diaryl esters of terephthalic acid.

Other dicarboxylic acids that can be used together in a range of 10 mol% or less as a dicarboxylic acid component include phthalic acid,
Isophthalic acid, adipic acid, sebacic acid, naphthalene
Examples include 1,4- or -2,6 dicarboxylic acid, diphenyl ether-4,4-dicarboxylic acid, and the like.

Other glycols that can be used in combination as a glycol component in an amount of 10 mol % or less include glycols such as propylene chol, cyclohexanedimethanol, 2,2-bis(4-4'doroquinphenyl)furo, and 47.

As other components used in obtaining the polyester of Ikemizu's invention, bovine acid such as p-hydroxybenzoic acid and p-hydroxyethoxybenzoic acid can also be used in combination.

The PBT resin (B) used in the present invention is a polymer obtained by polycondensation of terephthalic acid or a dialkyl ester of terephthalic acid and 1,4-butanediol.

A portion of terephthalic acid may be replaced with other dibasic acids or polybasic acids, and a portion of 1,4-butanediol may be replaced with other diols or polyhydric alcohols.

The blending amount of PBT resin (B) is the same as that of PET copolymer (A).
A suitable amount is 5 to 450 parts by weight per 100 parts by weight. In a resin composition containing less than 5 parts by weight of PBT resin (B), the surface appearance of the molded product obtained by molding the bottom at a mold temperature of 80°C is poor, and the heat distortion temperature (hereinafter abbreviated as HDT) is poor. )
is low.

On the other hand, a resin composition in which the amount of PBT (B) exceeds 1 part of 450fi is not preferred because the resulting molded product will have a poor surface appearance.

Examples of the double-terminated polyalkylene glycol (C) used in the present invention include polyethylene glycol, polypropylene glycol, polytrimethylene glycol, polytetramethylene glycol, and polyethylene glycol and polytetramethylene glycol/L/! A random or block copolymer, etc., in which the hydrogens of both terminal hydroxyl groups are substituted with one selected from an alkyl group, an aryl group, and an aralkyl group. Examples of the alkyl group, aryl group, and aralkyl group include methyl group, ethyl group, phenyl group, benzyl group, and methylphenyl group.

The weight average molecular weight of the polyalkylene glycol endblocked at both ends is preferably in the range of 500 to 4,000. Molecular weight is 500
A polyester resin composition using a polyalkylene glycol endblocked at both ends has a large plasticizing effect, resulting in a decrease in the mechanical strength of the resulting molded product, which is undesirable.

Furthermore, a resin composition using a double-end-capped polyalkylene gelcol with a molecular weight exceeding 4,000 is not preferable because it has a small crystallization promoting effect and the mechanical properties of the resulting molded product are deteriorated.

The composition of the double end-capped polyalkylene glycol is PET.
System resin (A) 100f [0.5 to 8 for Jlg
It is preferably in the range of parts by weight, more preferably 0.5 to 8 parts by weight.
Parts by weight ranges are preferred. A resin composition containing less than 0.5 parts by weight is not preferred because the effect of promoting crystallization during the molding process is small. Furthermore, the mechanical properties of molded products obtained from resin compositions containing more than 8 parts by weight are extremely reduced.

The crystallization promoter (C) used in the present invention includes metal salts of Group 1a or Group 11a of the periodic table of organic carboxylic acids;
benzoic acid ester or ester of benzoic acid ester,
Examples include fatty acid esters, metal salts of ionic copolymers, and inorganic particles effective as crystallization promoters. Specifically, storium laurate, potassium laurate, sodium myristate, potassium myristate, carunium myristate, sodium stearate, potassium stearate, calcium stearate, sodium octacosanoate, calcium octacosanoate, sodium benzoate, benzoate. potassium acid, calcium benzoate, lithium terephthalate, potassium terephthalate, potassium terephthalate, ethylene glycol monobenzoate,
Ethylene glycol dibenzoate, propylene glycol monobenzoate, propylene glycol dibenzoate, neopentyl glycol monobenzoate, diethylene glycol dibenzoate, triethylene glycol dibenzoate, ethylene glycol propylene glycol dibenzoate, ethylene-sodium acrylate copolymer, ethylene-methacrylate Acid sodium copolymers, talc, titanium oxide, zinc oxide, etc., and combinations thereof can be used.

In the present invention, compounds such as polyoxyethylene derivatives, epoxy compounds, sorbitan derivatives, etc. can also be added which, when used in combination with these crystallization promoters, further improve the crystallization rate of the resin molded product.

The amount of crystallization accelerator is PET copolymer (A) 10
0.1-50 parts by weight is suitable for 0 parts by weight.

A molded article obtained from a resin composition containing less than 0.1 part by weight has a low degree of crystallinity and poor heat resistance. On the other hand, the blending amount is 5
If the resin composition exceeds 0 parts by weight, deterioration during molding will be large and molding will become difficult, which is not preferable.

Depending on the purpose, the polyester resin composition of the present invention may contain fibrous fillers such as glass fiber, alumina fiber, carbon fiber, silicon carbide fiber, ceramic fiber, asbestos fiber, and metal fiber, talc, kaolin, mica, and clay. Silicates such as lastite, sericite, bentonite, asbestos, alumina silicate, alumina, silicon oxide, magnesium oxide, zirconium oxide,
Metal oxides such as titanium oxide, carbonates such as calcium carbonate, magnesium carbonate, dolomite, calcium sulfate,
Sulfates such as barium sulfate, particulate fillers such as glass peas, boron nitride, and silicon carbide, lubricants and mold release agents such as silica and stearate, ultraviolet absorbers, colorants including pigments such as carbon black, Known additives such as flame retardants such as halogen compounds and phosphorus compounds, flame retardant aids, antioxidants, antistatic agents, and heat stabilizers may be optionally added. In addition, small amounts of other thermoplastic resins (e.g. polyethylene, polypropylene, olefin resins such as ethylene copolymers, acrylic resins, fluororesins, polyamides, polyacetals, polycarbonates, polysulfones,
Graft copolymers such as polyphenylene oxide, polyester elastomer, ABS resin, MBS resin, etc.) and thermosetting resins (for example, phenol resins, melamine resins, polyester resins, silicone resins, epoxy resins, etc.) can be blended.

When manufacturing a molded article from the polyester resin composition of the present invention, as in the past, a predetermined amount of the composition components is put into a kneading machine such as an extruder, and after melt-kneading and pelletizing, injection A molded article can be obtained by subjecting it to molding such as molding or extrusion molding.

[Example] Hereinafter, the present invention will be specifically explained with reference to Examples.

Examples 1 to 10 PET resin, ([77] = 0.77), PBT resin, X polyethylene glycol dimethyl ether (PEG
(abbreviated as DME) and a crystallization promoter were blended in the proportions shown in Table 1, and the mixture was mixed for 5 minutes in a V-type blender to homogenize. The obtained mixture was put into a vent type melt extruder with a diameter of 40 mm, and the cylinder temperature was 260 to 280.
A pellet of the resin composition of the present invention was obtained by extrusion at .degree.

The crystallization rate of the resin composition obtained here was measured using a differential calorimeter (DSC), and the crystallization rate was measured using a 3 oz.
Using a 2mm screw injection molding machine, an ATSM No. 1 dumbbell specimen was molded at a cylinder temperature of 270°C and a mold temperature of 80"C1 molding cycle for 30 seconds.
A tensile test was carried out according to D 638. The evaluation results of various physical properties are shown in Table 1.

The symbol for crystallization promoter (c) in the table below means the following.

D-1: Talc D-2 = Sodium benzoate D-3: Polyoxyethylene monononylphenyl ether D-4: Polyoxyethylene dinonylphenyl ether D-5: Ethylene/methacrylic acid (weight ratio 85/15)
60% of methacrylic acid is neutralized with a copolymer.

Moreover, the moldability in Table 1 was evaluated based on the following criteria.

〇 - Good, △ - Slightly poor mold releasability, × - Poor mold releasability The symbols for the evaluation results of surface appearance in Table 1 have the following meanings.

Evaluation results of surface appearance 〇 - Good gloss △ - Slightly glossy A resin composition was produced in the same manner as in the above example, except that it was outside the scope of the present invention, and various physical properties were evaluated. The results are shown in Table 1.

As is clear from the table, in Examples 1 to 10, the mechanical properties were improved by blending component (B), component (C), and component (D) with PET resin, and the mold temperature was 80°C. However, we were able to obtain a molded product with good moldability.

On the other hand, as shown in Comparative Example 1.2, if component (B) is not blended, or even if it is blended, the blended amount is small,
The heat resistance of the resulting molded product decreases and the surface appearance deteriorates. As shown in Comparative Example 3, when the blending amount of component (B) is large, the surface appearance becomes poor. Also, Comparative Example 4.5
As shown in , if the amount of component (D) is too little or too much, the moldability and the tensile strength and heat resistance of the resulting molded product will decrease. Furthermore, if the amount of component (D) is large, the Izo impact strength of the resulting molded product will also decrease.

Furthermore, as shown in Comparative Example 6.7, when component (C) was not blended, moldability was poor, and the resulting molded product was poor in surface appearance and heat resistance.

[Effects of the Invention] As detailed above, the polyester resin composition of the present invention can be injection molded using a low temperature mold of about 80°C, and has excellent surface appearance and heat resistance. It is possible to obtain molded products with excellent quality.

Claims (1)

[Claims] (A) 100 parts by weight of polyethylene terephthalate resin whose main repeating unit is ethylene terephthalate, and 5 to 4 parts by weight of (B) polybutylene terephthalate resin.
50 parts by weight, (C) hydrogen of both terminal hydroxyl groups is an alkyl group,
0.5 to 8 parts by weight of a double-terminated polyalkylene glycol substituted with either an aryl group or an aralkyl group and having a weight average molecular weight of 500 to 4,000, and (D) 0.1 to 50 parts by weight of a crystallization promoter. polyester resin composition.