JPH0364353A - 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 specified polyethylene terephthalate copolymer with a specified polybutylene terephthalate copolymer. CONSTITUTION:A polyester resin composition is obtained by mixing 100 pts.wt. polyethylene terephthalate, prepared by polycondensing 65-97.8% polyethylene terephthalate oligomer prepared by esterifying a terephthalic acid (derivative)- based dicarboxylic acid component with an ethylene glycol-based diol component with 1-20% polyalkylene glycol and 1.2-15% diethylene glycol, with 5-450 pts.wt. polybutylene terephthalate copolymer obtained from a terephthalic acid (derivative)-based dicarboxylic acid component and a diol component based on 1,4-butanediol and a polyalkylene glycol, wherein the polyalkylene glycol component is contained in an amount of 1-10% based on this copolymer.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention can provide a molded article having excellent mechanical properties, thermal properties, chemical resistance, and appearance, and also has excellent moldability. The present invention relates to a polyester 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 molding was performed at a low mold temperature of 100° C. or lower, the crystallization of the resin did not proceed sufficiently, resulting in poor releasability of the molded product from the mold. Therefore, in order to improve the mold releasability, 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 promoters to mold PET at low mold temperatures. For example, in PET, α-oL/fint α, β-
Japanese Patent Publication No. 45-26225 discloses a method of adding an ionic copolymer consisting of an unsaturated carboxylic acid salt Tokara. In addition, a method of adding polyalkylene glycol and an inorganic filler such as talc to PET was introduced in 1973.
It is disclosed in the publication No.-3027. Furthermore, JP-A-59-229 describes a system in which PET is combined with an ionic copolymer, a polyalkylene gellicol compound, and an inorganic filler.
It is disclosed in Publication No. 58.

Also known are methods for improving the crystallization rate by copolymerizing a soft segment with PET or 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, the temperature that can be controlled by an economical hot water circulation type temperature control device as a mold for molding such a PET-based composite composition,
For example, when injection molding is performed using a mold with a mold temperature of about 8 G'C, although the mold release properties during molding and the mechanical strength of the resulting molded product are good, the appearance of the molded product is not necessarily satisfactory. It wasn't worth it.

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 ET/PBT = 30/TO to 2G/80 (weight ratio), the molded product obtained by molding at a mold temperature of 80''C did not exhibit a good surface appearance. Even if the amount of PET is larger than the amount of PET, the molding cycle when molding a molded article from the resin composition is
The molding cycle was not satisfactory compared to the molding cycle when molding from BT alone.

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

[Means for Solving the Problems J] In view of the current situation, the present inventors have conducted extensive research and have found that a resin composition made by blending a specific PBT copolymer with a specific PET copolymer has been developed. The inventors have discovered that it is possible to provide a molded article with excellent surface appearance and mechanical properties even when molded in a low-temperature mold, and have thus arrived at the present invention.

That is, the present invention provides (A) dicarboxylic acid W! mainly composed of terephthalic acid and its derivatives. PET oligomer (a) 65 obtained by esterifying component (a-1) and diol component (a-2) mainly composed of ethylene glycol
~97.8% by weight, average molecular weight SQG ~2Q, 000
A PET copolymer obtained by polycondensing 1 to 20% by weight of polyalkylene glycol (b) and 1.2 to 15% by weight of diethylene glycol (C).
(B) dicarboxylic acid component (d) mainly consisting of terephthalic acid and its derivatives, 1.4-butanediol (e-1) and an average molecular weight of 11 soo to 20.000 in parts by weight.
A polybutylene terephthalate copolymer obtained from a polyalkylene glycol (e-2) of Contained P
This is a polyester resin composition containing 5 to 450 parts by weight of a BT copolymer.

In the present invention, the polyester resin composition is further blended with 5 to 50 parts of (C) a crystallization promoter to 100 parts by weight of the polyester resin composition. You can also do it.

The PET copolymer (A) used in the resin composition of the present invention comprises a dicarboxylic acid component (a-1) mainly composed of terephthalic acid and its derivatives and a diol component (a-2) mainly composed of ethylene glycol. P obtained by esterifying
ET oligomer (a) and an average molecular weight of 500 to 20.
000 polyalkylene glycol (b) and diethylene glycol (C).

The PET oligomer (a) used in the present invention preferably has a dicarboxylic acid component (at least 90 mol% of which is terephthalic acid and derivatives thereof, such as dimethyl ester).
It is obtained by direct esterification or transesterification from a-1) and a diol component (a-2), preferably at least 90 mol% of which is ethylene glycol.

Examples of substances that can be used in combination with terephthalic acid or its derivatives in a proportion of 0 to 10 mol% in the dicarboxylic acid component (a-1) include phthalic acid, isophthalic acid, adipic acid, sebacic acid, naphthalene-1,4- or - Examples include 2,6-dicarboxylic acid, diphenyl ether-4,4-dicarboxylic acid, and derivatives thereof, such as dimethyl esters of these dicarboxylic acids.

In addition, examples of glycols that can be used in combination with ethylene glycol in a proportion of 0 to 10 mol% in the diol component (a-2) include propylene glycol, butylene glycol,
Examples include neopentyl glycol, cyclohexanedimethanol, 2,2-bis(4-hydroxyphenyl>propane), and the like.

In addition, oxyacids such as p-hydroboxybenzoic acid, p-hydroxymethylbenzoic acid, p-hydroxyethylbenzoic acid, etc. can also be used in a range of 10 mol% or less (based on 1 mol condensate unit of dicarboxylic acid and diol). It can be used in

Examples of the polyalkylene glycol (b) used in the present invention include polyethylene glycol, polypropylene glycol, polytrimethylene glycol, polytetramethylene glycol, and random or block copolymers of polyethylene glycol and polytetramethylene glycol. .

The weight average molecular weight of polyalkylene glycol is SOO ~
In the range of 20.000, preferably 1,000 to a, o
It is in the range of oo. When a weight average molecular weight of less than 50Q is used, mold release properties when molded using a low-temperature mold are poor, and the heat resistance of the resulting molded product is reduced.

On the other hand, when a resin having a molecular weight exceeding 20,000 is used, the retention stability of the resin composition during molding is poor.

The optimal copolymerization 1 of polyalkylene glycol (b) is
Although it varies depending on its average molecular weight, in order to achieve the desired purpose, polyalkylene glycol is copolymerized in a proportion of 1 to 20% by weight, preferably 2 to 5% by weight, in the PET copolymer (A). A resin composition using a PET copolymer with a copolymerization amount of less than 1% by weight does not have a remarkable crystallization promoting effect, and a resin composition using a PET copolymer with a copolymerization amount of more than 20% by weight The composition has reduced retention stability during molding.

The PET copolymer (A) used in the present invention is a copolymer of diethylene glycol (C) (hereinafter abbreviated as DEG) in addition to the above-mentioned polyalkylene glycol (b). The copolymerization amount of DEG is 1.2 to 15
% by weight, preferably from 1.5 to io weight %.

In a resin composition using a PET copolymer with a DEC copolymerization amount of 1.2% by weight, the appearance of the molded product in a low-temperature mold is insufficient, and the copolymerization amount exceeds 15% by weight. PET
A system copolymer is not preferable because its melting point decreases significantly.

The PBT copolymer (B) used in the present invention is a dicarboxylic acid component (d) mainly composed of terephthalic acid and its derivatives.
and 1,4-butanediol (e-1) with an average molecular weight of 5
00-20.000 polyalkylene glycol (e-
It is a copolymer obtained from diol component (e) mainly consisting of (2) and (e).

The dicarboxylic acid component (d) used in the present invention is at least 90 mol% tylphthalic acid or a derivative thereof. Examples of derivatives of terephthalic acid include dialkyl esters and diaryl esters of terephthalic acid. Other dicarboxylic acids that can be used together in the dicarboxylic acid component (d) in an amount of 10 mol% or less include phthalic acid, isophthalic acid, adipic acid, sebacic acid, and naphthalene-1.
, 4- or -2,6 dicarboxylic acid, diphenyl ether-4,4-dicarboxylic acid, and the like.

The diol component (e) used in the present invention is 1.4-butanediol (e-1) and has an average molecular weight of 500 to 20°00.
0 polyalkylene glycol (e-2). Other glycols that can be used in combination in a range of 10 mol% or less in the diol component (e) include ethylene glycol, propylene glycol, neopentyl glycol, cyclohexane dimethanol, 2,2-bis(4-hydroxy phenyl)propane, etc.

Polyalkylene glycol (e-2) used in the present invention
Examples include polyethylene glycol, polypropylene glycol, polytrimethylene glycol, polytetramethylene glycol, and random or block copolymers of polyethylene glycol and polytetramethylene glycol.

The weight average molecular weight of polyalkylene glycol (e-2) is in the range of SOO to 20.000, preferably 1.00.
It is in the range of 0 to s, ooo. If a weight average molecular weight of less than 500 is used, the heat resistance of the resulting molded product will be reduced. On the other hand, when a polymer having a molecular weight exceeding 20,000 is used, the retention stability during molding is poor.

The optimum copolymerization amount of polyalkylene glycol (e-2) varies depending on its average molecular weight, but in order to achieve the desired purpose, it is necessary to add 1 to 10
% by weight, preferably 2-5% by weight.

In a resin composition using a PBT copolymer with a polyalkylene glycol (e-2) copolymerized amount of less than 1% by weight, the effect of promoting crystallization is not remarkable, and in addition, when the copolymerized amount exceeds 10% by weight, In a resin composition using a PBT copolymer,
Retention stability during molding decreases.

In addition, oxyacids such as p-hydroxybenzoic acid, p-hydroxymethylbenzoic acid, p-hydroxyethylbenzoic acid, etc. are also used in a range of 10 mol% or less (based on 1 mol condensate unit of dicarboxylic acid and diol). can do.

The blending amount of the PBT copolymer (B) is the same as that of the PET copolymer (B).
A) 10011! A suitable amount is 5 to 450 parts by weight, and resin compositions containing less than 5 parts by weight will have poor surface appearance and thermal deformation when molded at a mold temperature of 80''C. The temperature is low.On the other hand, if the amount exceeds 450 parts by weight, the appearance of the resulting molded product will be poor, which is not preferable.

The resin composition of the present invention is basically composed of the above-mentioned PET copolymer (A) and PBT copolymer (B),
Depending on the purpose of use, in addition to these, crystallization accelerator (C)
It can also be used as a highly crystalline polyester resin composition.

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

In the present invention, compounds that further improve the crystallization rate during molding of the resin composition, such as polyoxyethylene derivatives, epoxy compounds, sorbitan derivatives, etc., may be added to these crystallization promoters in combination. can.

The blending amount of the crystallization accelerator is as follows: PET copolymer (A) lo
0.1 to 50 parts by weight is appropriate.

A molded article obtained from a resin composition containing less than 1 part of o or xf has a low degree of crystallinity and poor heat resistance. A resin composition containing more than 50 parts by weight is not preferable because it causes significant deterioration during molding and makes molding difficult.

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. olefin resins such as polyethylene, polypropylene, ethylene monopolymer, acrylic resins, fluororesins, polyamides, polyacetals, polycarbonates, polysulfones,
Graft copolymers such as polyphenylene oxide, polyester elastomer ABSJ1 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 mixing machine such as an extruder, melted and kneaded to form pellets, and then injection A molded article can be obtained by subjecting it to molding such as molding or extrusion molding. At this time, the feature is that molding can be performed at a mold temperature of 80° C. or lower.

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

Examples 1 to 6 PET oligomers synthesized by direct esterification were combined with 5% by weight of polyethylene glycol (hereinafter abbreviated as PEG) having an average molecular weight of 4.000 and 1.3% by weight of diethylene glycol (hereinafter abbreviated as DEC). Polymerize, P
An ET copolymer (A-1>) was obtained.

Since DEC is produced as a 0.9% by weight by-product in the PET oligomer, the content of DEC in the copolymer (A-1) was 2.2% by weight. In addition, PBT oligomer synthesized by the direct esterification method was copolymerized with PEG31i weight % having an average molecular weight of 1.000, and PBT
A copolymer (B-1) was obtained. This copolymer (A-1)
A PBT copolymer (B-1) was added to the mixture in the proportions shown in Table 1, and the mixture was mixed for 5 minutes in a V-type blender to homogenize it. The resulting mixture was put into a vent-type melt extruder with a diameter of 40 mm and extruded at a cylinder temperature of 260 to 280°C to obtain pellets of the resin composition of the present invention.

Using a screw injection molding machine with a diameter of 32 mm, 3 ounces of the resin composition obtained here was molded at a cylinder temperature of 270.
℃, mold temperature 80℃, molding cycle 30 seconds ATSM
Molding a No. I dumbbell specimen, A, S T MD63
A tensile test was conducted according to No. 8.

Further, the Izot impact strength was evaluated according to ASTM D 256, the HDT was evaluated according to ASTM D 64B, and the surface appearance of the molded product was evaluated using an ASTM I dumbbell test piece molded at 80°C. The evaluation results of these physical properties are shown in Table 1.

The symbols for the surface appearance evaluation results in Table 1 have the following meanings.

Surface appearance evaluation results 〇 - Good gloss △ - Slightly glossy X - Poor gloss Comparative Examples 1 to 5 PET homopolymer (A-2) or PBT copolymer A resin composition was prepared in the same manner as in Example 1, except that PBT homopolymer (B-2) was used instead of polymer (B) and the amount of component (B) added was outside the range of the present invention. were manufactured and evaluated for various physical properties, and the results are shown in Table 1.

Examples 7 to 10 PET copolymer (A-1), PBT copolymer (B-
1) and the crystallization promoter (C) in the composition shown in Table 1.
．． A resin composition was produced in the same manner as in Example 1, and various physical properties were evaluated. The results are shown in Table 1.

In addition, the symbol of the crystallization promoter (C) in the table below is
means the following:

C-1: Talc C-2 = Sodium benzoate C-3 = Polyoxyethylene monononylphenyl ether C-4: Pholyoxyethylene dinonylphenyl ether C-5: Ethylene/methacrylic acid Cf1jl ratio 8571
5> 60% of methacrylic acid neutralized with copolymer.

Example 1l-16 PET copolymer (A-1), PBT copolymer (B-
1), crystallization accelerator (C) and chopped strand glass fiber of 3n+m length (this is abbreviated as GF in the table).

) was made into the composition shown in Table 2, a resin composition was produced in the same manner as in Example 1, and various physical properties were evaluated, and the results are shown in Table 2.

Examples 17-20 Polytetramethylene glycol (hereinafter abbreviated as PTMG) with an average molecular weight of N and ooo (hereinafter abbreviated as PTMG) and DEC2 were added to a PET oligomer synthesized by a direct esterification method in an amount of 10% by weight.
, 0% by weight to form a PET copolymer (A-3)
I got it. The content of DEC in the PET copolymer (A-3) was 2.9% by weight.

In addition, 3% by weight of PTMG with an average molecular fi of 4.000 was added to the PBT oligomer synthesized by the direct esterification method.
was copolymerized to obtain a PBT copolymer (B-3).

PET copolymer (A-1, A-3), PBT copolymer (B-1, B-3), crystallization accelerator (C) and 3n
A resin composition was produced in the same manner as in Example 1 using +n+ long knobbed strand glass fibers (abbreviated as GF in the table) shown in Table 2, and various physical properties were evaluated. The results are shown in Table 2.

Comparative Examples 6 to 9 Using PET homopolymer (A-2) instead of PET copolymer (A), or PBT homopolymer (B2) instead of PBT copolymer (B), and A resin composition was produced in the same manner as in Example 1, except that the amount of component (B) added was outside the range of the present invention, and various physical properties were evaluated. The results are shown in Table X.

As is clear from the table, in Examples, PB was added to the PET copolymer.
By blending the T copolymer, it was possible to obtain a molded product with improved mechanical properties, good moldability even at a mold temperature of 80''C, and an excellent surface appearance.

On the other hand, as shown in Comparative Example 1.2, if the component (B) is not blended, or if it is blended, the amount blended is small, the heat resistance of the resulting molded product is lowered and the surface appearance is also poor. Furthermore, as shown in Comparative Example 3, when the amount of component (B) is large, the surface appearance is poor. As shown in Comparative Example 4.5, a PET homopolymer was used as the pace polymer instead of the PET copolymer (A), or a PBT copolymer (
When PBT homopolymer was used instead of B), the molded product obtained was inferior in surface appearance and heat resistance.

[Effects of the Invention] The polyester resin composition of the present invention can be injection molded using a low-temperature mold of about 80°C, and can yield molded products with excellent surface appearance and heat resistance. .

Claims (1)

[Claims] 1) (A) Polyethylene obtained by esterifying a dicarboxylic acid component (a-1) mainly composed of terephthalic acid and its derivatives and a diol component (a-2) mainly composed of ethylene glycol. Terephthalate oligomer (a) 6
5-97.8% by weight, average molecular weight 500-20,00
For 100 parts by weight of a polyethylene terephthalate copolymer obtained by polycondensing 1 to 20% by weight of 0 polyalkylene glycol (b) and 1.2 to 15% by weight of diethylene glycol (c), (B) terephthal A dicarboxylic acid component (d) mainly consisting of acids and derivatives thereof, 1,4-butanediol (e-1) and an average molecular weight of 50
0 to 20,000 polyalkylene glycol (e-2
) A polybutylene terephthalate copolymer obtained from a diol component (e) mainly consisting of A polyester resin composition containing 5 to 450 parts by weight of a polymer. 2) The polyester resin composition according to claim 1 further contains the polyethylene terephthalate copolymer (A) 10
A polyester resin composition containing 5 to 50 parts by weight of (C) a crystallization promoter based on 0 parts by weight.