JPS62295948A - Polyester resin composition - Google Patents

Abstract

PURPOSE:To obtain a resin compsn. having good low-temperature moldability in die as well as excellent rigidity and impact strength, by blending PET with an acrylic rubber, a metal salt of a copolymer composed of an alpha-olefin and an alpha,beta-unsaturated carboxylic acid and a reinforcing filler. CONSTITUTION:A resin compsn. is obtd. by blending 100pts.wt. polyethylene terephthalate (PET) (A) with 10-50pts.wt. acrylic rubber (B), 1-20pts.wt. metal salt (C) of a copolymer composed of an alpha-olefin and an alpha,beta-unsaturated carboxylic acid and 10-100pts.wt. reinforcing filler (D). In addition to the components A-D, not more than 10pts.wt. (per 100pts.wt. PET) polyalkylene glycol (E) may be added to the compsn. to improve moldability, surface smoothness, heat resistance, etc.

Description

[Detailed description of the invention] 3. Detailed description of the invention [Industrial application field] The present invention relates to polyester resin compositions.

More specifically, the present invention is suitable as a molding material for, for example, automobile engine parts, electric tool connectors, etc.
The present invention relates to a polyester resin composition that not only has good moldability at low temperatures, but also has excellent rigidity and high impact strength, and provides lightweight molded products with good surface gloss.

[Conventional technology]

Polyethylene terephthalate is a thermoplastic resin with excellent heat resistance, chemical resistance, mechanical properties, electrical properties, etc., and is widely used in many fields as a material for fibers, films, and various molded products.

In particular, polyethylene terephthalate reinforced with inorganic fillers such as glass fibers has significantly improved thermal and mechanical properties, so it has recently attracted attention as an engineering plastic and is widely used in various molded products.

However, when filler-reinforced polyethylene terephthalate is intended to be used for injection molding applications, it is known that it has major drawbacks in terms of molding and physical properties due to the crystallization temperature of polyethylene terephthalate. In other words, since polyethylene terephthalate has a low crystallization rate at low temperatures, for example, when injection molding is performed at a mold temperature of 130°C or lower, a molded product with good crystallization is particularly difficult to mold with poor surface hardness. In addition, if this molded product is used at a temperature above the secondary transition point, crystallization will progress, resulting in poor shape stability. Because it does not crystallize, there are problems such as roughness on the surface of the molded product.Therefore, molding of polyethylene terephthalate usually requires 1
This is done using a special molding machine that can obtain a mold temperature of 30℃ or higher, but since such a molding machine is not common, a molding machine that has a mold temperature of 90 to 110℃ or less, which is commonly used, is used. Polyethylene terephthalate resin compositions that can be favorably molded using this method have been studied, and various compositions have been proposed so far.

For example, a copolymerized polyester resin obtained by copolymerizing terephthalic acid, ethylene glycol, and polyalkylene glycol is blended with a filler reinforcing substance, a sodium or potassium salt of a polymer containing a carboxyl group, and polyalkylene glycol. A polyester resin composition has been proposed (Japanese Patent Application Laid-Open No. 60-2238
Although this composition has good low-temperature moldability and can give a molded article with relatively good surface gloss, it has the disadvantage that the rigidity of the molded article is impaired. There is. Furthermore, in order to prevent a decrease in rigidity, the blending ratio of filler reinforcing substances has been increased, but in this case, a problem arises in that the specific gravity inevitably increases.

On the other hand, in order to improve impact strength while maintaining good moldability at low temperatures, polyethylene terephthalate is blended with an alkali metal salt of a higher fatty acid having 26 or more carbon atoms, acrylic rubber, and a fibrous reinforcing material. A thermoplastic polyester resin composition is known (Japanese Unexamined Patent Application Publication No. 1983-1999)
Although this composition has relatively good low-temperature formability, it is not necessarily satisfactory in improving impact strength.

[Problem that the invention seeks to solve]

Under these circumstances, the purpose of the present invention is to provide a molded product that has good low-temperature mold formability, has improved impact strength without impairing rigidity, has excellent surface gloss, and is lightweight.
An object of the present invention is to provide a polyester resin composition having excellent characteristics.

[Means for solving problems]

As a result of intensive research to develop a polyester resin composition having the above-mentioned excellent characteristics, the present inventors have discovered that polyethylene terephthalate can be combined with acrylic rubber, certain ionomers, filler reinforcing substances, and as desired. It was discovered that the objective could be achieved by blending polyalkylene glycol in a predetermined ratio, and based on this knowledge, the present invention was completed.

That is, the present invention provides 10 to 5 parts by weight of (B) acrylic rubber to 100 parts by weight of (A) polyethylene terephthalate.
0 weight IHB, (C) 1 to 20 parts by weight of a metal salt of a copolymer of an α-olefin and an α,β unsaturated carboxylic acid, (D) 10 to 100 parts by weight of a filler reinforcing substance, and optionally (
E) A polyester resin composition characterized in that it contains 10 parts by weight or less of polyalkylene glycol.

t; In the composition of the present invention, the polyethylene terephthalate (hereinafter abbreviated as PET) used as component (A) is a linear polyester obtained by condensation polymerization of terephthalic acid or dialkyl terephthalate with ethylene glycol, terephthalate. Examples include a copolyester containing an acid or dialkyl terephthalate and ethylene glycol as main components, and a copolymerizable third component copolymerized therewith, and a mixture of the linear polyester and the copolyester.

Examples of the third component include acid components such as isophthalic acid, naphthalene-2,6-dicarboxylic acid, adipic acid, diphenyl ether-4,4'-dicarboxylic acid, and sebacic acid, propylene glycol, neopentyl glycol, diethylene glycol, Glycol compounds such as cyclohexane dimetatool, 2,2-bis(hydroxyphenyl)propane, polyalkylene gelcols, p
-oxyacids such as oxybenzoic acid and p-hydroxyethoxybenzoic acid.

Among these third components, polyalkylene glycol is preferred. As this polyalkylene glycol,
For example, polyethylene glycol, polypropylene glycol, polybutylene glycol, glycol of a copolymer of ethylene oxide and propylene oxide, or derivatives in which one end of these is bonded to an alkyl group, aryl group, aralyl group, etc. through an erther bond, an ether bond, etc. are used. However, when considering the surface smoothness of the molded product of the resulting polyester resin composition, polyethylene glycol is best, and it is important that the molecular weight of the polyalkylene glycol is in the range of 400 to 20,000. When the average molecular weight of the polyalkylene glycol component is less than 400 or greater than 20,000, not only the surface gloss is insufficient, but also the heat distortion temperature is lowered, resulting in poor heat resistance. The preferred average molecular weight is in the range of 400-6000.

The proportion of the third component in the copolymer is up to 25% by weight. If the third component is contained in an amount exceeding 25% by weight, the rigidity of the polyester composition will decrease.

The PET has an intrinsic viscosity of 0.4 or more, preferably 0.4°C, as determined by measuring a phenol/tetrachloroethane mixed solvent (1/1 weight ratio) solution at a temperature of 30°C.
It is desirable that it be 48 or more, more preferably 0.55 or more.

In the composition of the present invention, PET used as component (A)
Most preferred are terephthalic acid, ethylene glycol and copolymers with polyethylene glycol.

In the composition of the present invention, the acrylic rubber used as component (B) is, for example, a rubbery polymer obtained by polymerizing a monomer mainly composed of alkyl acrylate and/or alkyl methacrylate, or the presence of the rubbery polymer. Further examples include rubbers obtained by polymerizing styrene, alkyl methacrylate, etc. The alkyl group of the alkyl acrylate and alkyl methacrylate includes methyl, ethyl, propyl, butyl, and the like. Specific examples of acrylic rubber include JP-A-52-15
A multiphase composite copolymer as described in Japanese Patent No. 0466, ie 75-99.8% by weight of alkyl acrylate, 0.1-5% by weight of cross-linking monomer and 0.5% by weight of graft-linking monomer. A final hard material obtained by polymerizing a monomer mainly composed of alkyl methacrylate in the presence of 25 to 95% by weight of an initial elastic phase obtained by polymerizing a monomer consisting of 1 to 5% by weight. Thermoplastic phase 75-5% by weight
and preferably 95 to 99.8% by weight of butyl acrylate, 0.1 to 2.5% by weight of butylene diacrylate, and 0.1 to 2.5% of allyl methacrylate or diallyl maleate. The copolymer which becomes the initial elastic body phase by polymerizing the monomer system consisting of 60 to 90% of the total polymer! ! % by weight, and then polymerizing a monomer consisting of 60 to 100% by weight of methyl methacrylate in the presence of the copolymer. As a commercially available acrylic rubber, for example, KM-330 (manufactured by Rohm and Haas, trade name)
, Metaprene C-223 (manufactured by Mitsubishi Rayon, trade name)
Examples include.

In the composition of the present invention, these acrylic rubbers, P
It is blended in an amount of 10 to 50 parts by weight, preferably 20 to 45 parts by weight, per 100 parts by weight of ET. This amount is 10
If it is less than 50 parts by weight, the effect of improving impact strength is small;
If the amount exceeds 1 part by weight, low-temperature mold formability and surface gloss will deteriorate.

In the composition of the present invention, a metal salt of a copolymer of an α-olefin and an α,β-unsaturated carboxylic acid is used as component (C). Preferable examples of the α-olefin include ethylene and propylene, and examples of the α,β-unsaturated carboxylic acid include acrylic acid, methacrylic acid, maleic acid, and itaconic acid. Preferred examples of the salt include sodium, potassium, calcium, and aluminum salts.

This ionic copolymer consists of α-olefin and α.

It can be produced by copolymerizing a β-unsaturated carboxylic acid and then substituting a part or all of the carboxylic acid with a metal salt.

After graft polymerization of β-unsaturated carboxylic acid, by substituting with a metal salt or by adding α to polyolefin.
, graft polymerization of β-unsaturated carboxylic acid ester,
It can also be produced by saponifying the carboxylic acid ester moiety and then substituting it with a metal salt. Among these ionic copolymers, metal salts of copolymers of ethylene and acrylic acid or ethylene and methacrylic acid are particularly preferably used in the present invention.

Further, as the metal providing the cation of the ionic copolymer, an alkali metal, particularly sodium, is preferable.

In the ionic copolymer, the carboxyl group and its salt are preferably contained in an amount of 1 to 30 mol %. If this amount is less than 1 mol%, the effect of preventing substantial deterioration of PET will not be sufficiently exhibited, and the higher the content of carboxyl groups and their salts, the greater the effect, but if it exceeds 30 mol%. Then, in the molten state, the ionic copolymer cannot be sufficiently kneaded into PET in a short time. A more preferable content of this carboxyl group and its salt is in the range of 2 to 10 mol%.

Furthermore, in the ionic copolymer, it is not necessary that all of the carboxyl groups present be neutralized by metal ions, but it is desirable that at least 40 mol% of all carboxyl groups be neutralized by metal ions. . If the neutralization rate is less than 40 mol%, the effect of preventing substantial deterioration of PET will not be sufficiently exhibited.

α-olefin and α, β that constitute the ionic copolymer
- As a copolymer with unsaturated carboxylic acid, the molecular weight is 40
A variety of oligomers are used, ranging from oligomers with an average molecular weight of about 0 to those with a high molecular weight of several hundred thousand, but the most preferred are oligomers with an average molecular weight of 5.
,000 or less. A copolymer with an average molecular weight of 5,000 or less that is made into a metal salt has an average molecular weight of 5,000 or less.
Compared to metal chloride copolymers with more than
Moreover, since the melt after kneading has good fluidity, moldability is good. A commercially available product of this ionic copolymer is Himilan 1707 (manufactured by DuPont Mitsui Chemical Co., Ltd., trade name).

In the composition of the present invention, the α-olefin and α, β
- Metal salt of copolymer with unsaturated carboxylic acid is PET1
1 to 20 parts by weight, preferably 3 to 1 parts by weight per 00 parts by weight
It is blended in a proportion of 5 parts by weight. If this amount is less than 1 part by weight, the effect of improving low-temperature mold formability is insufficient;
If the amount exceeds parts by weight, the mechanical strength will decrease.

In the composition of the present invention, examples of filler reinforcing substances used as component (D) include talc, calcium carbonate (
(heavy, light, colloid, etc.), mica, barium sulfate, calcium silicate, clay, magnesium carbonate, wollastonite, alumina, silica, iron oxide, calcium sulfate,
Glass peas, glass powder, white carbon, hollow glass bulbs, silica sand, silica stone, carbon black, aluminum hydroxide, magnesium hydroxide, zinc oxide, white enamel,
Basic magnesium carbonate, asbestos, zeolite, molybdenum, titanium oxide, diatomaceous earth, sericite, shirasu, graphite, calcium hydroxide, calcium sulfite, quartz powder, bentonite, metal whiskers, sodium sulfate,
Magnesium oxide fiber, fibrous magnesium oxysulfate, magnesium hydroxide fiber, potassium titanate fiber, glass fiber, calcium silicate fiber, carbon fiber,
Examples include rock wool, silicon nitride whiskers, silicon carbide whiskers, ceramic fibers that are alumina-silica glass fibers, and Ceracola fibers, among which glass fibers are preferred.

These filler reinforcing substances may be used alone or in combination of two or more. Further, the filler reinforcing substance may be used as it is, or may be used after surface treatment or sizing agent treatment.

In the composition of the present invention, the filler reinforcing material is P
It is blended in an amount of 10 to 100 parts by weight, preferably 50 to 90 parts by weight, based on 100 parts by weight of ET. This amount is 1
If it is less than 0 parts by weight, impact resistance and rigidity will be low;
If it exceeds 0 parts by weight, low-temperature molding properties will be poor.

In the composition of the present invention, in addition to the above-mentioned components (A) to (D), in order to further improve moldability, surface smoothness, heat resistance, etc., polyalkylene glycol may be added as component (E) to PET100. It can be blended up to 10 parts by weight. If this amount exceeds 10 parts by weight, embossment will occur on the surface of the molded product and the rigidity will decrease.

This polyalkylene glycol has the general formula % (in the formula, R8 and R'l are hydrogen atoms or lower alkyl groups, R1 is an alkylene group having 2 to 4 carbon atoms, and n is a number of 5 or more). The one expressed as is used. Specific examples of the polyalkylene glycol include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and their mono- or dialkyl ethers (such as monomethyl or dimethyl ether, monoethyl or diethyl ether, monopropyl or dipropyl ether, monobutyl or butyl ether, etc.). ) can be mentioned.

Polyalkylene glycols with alkyl ethers at both ends are suitable when using PET with a low degree of polymerization, since the inherent viscosity of PET decreases little during molding, and only one end is etherified. Monoalkyl ethers and polyalkylene glycols having hydroxyl groups at both ends significantly reduce the intrinsic viscosity of PET during molding, and are therefore suitable when using PET with a high degree of polymerization.

The polyalkylene glycol preferably has a degree of polymerization of 5 to 150. If the degree of polymerization is less than 5, it will easily stand out on the surface of the molded product, while if it exceeds 150, it will affect the surface smoothness and heat resistance of the molded product. Sexual improvement becomes insufficient. As the polyalkylene glycol used in the composition of the present invention, polyethylene glycol having a degree of polymerization of 10 to 50 is suitable.

In addition to the above-mentioned components, the composition of the present invention may contain additives commonly used for PET, such as colorants, mold release agents, ultraviolet stabilizers, antioxidants, flame retardants, etc., as desired. However, within the scope of not impairing the purpose of the present invention,
Other polymers may also be mixed.

The composition of the present invention is prepared by mixing the components using any known means. For example, PET can be mixed (B), (C), (
D) and optionally added component (E),
Prepared by melt extruding this mixture, or by mixing components (B), (C), (D) and optionally added component (E) with the molten resin at the final stage of PET polymerization, and extruding the mixture as it is. can do. Also, P
After melting and kneading components other than the CD component into the ET, (D
It is also possible to adopt a method of blending component (D) or, conversely, a method of melt-kneading other components into PET containing component (D).

The composition of the present invention does not require any special molding method or molding conditions, and can be molded under the same conditions as those used for molding ordinary thermoplastic resins.

EXAMPLES Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples in any way.

The physical properties and moldability of the molded product were evaluated as follows.

+11 Surface gloss: Compliant with JIS K7105 (2
)Izotsu impact strength: Conforms to JIS K7110 (3) Flexural modulus: Conforms to JIS K7106 (4)
Density: Compliant with JIS K7112 (5) Evaluation of moldability: Evaluated by mold release during injection molding, spool removal, etc.

○: Good ×: Bad In addition, the following components were used.

(A) Polyethylene terephthalate a: Polyethylene terephthalate obtained from terephthalic acid and ethylene glycol B: Copolymerized polyethylene terephthalate obtained from terephthalic acid, ethylene glycol and polyethylene glycol containing 5% by weight of polyethylene glycol C: Polyethylene glycol The copolymerized polyethylene terephthalate d containing 28% by weight of polyethylene glycol: The copolymerized polyethylene terephthalate e containing 10% by weight of polyethylene glycol: The copolymerized polyethylene terephthalate containing 17% by weight of polyethylene glycol f: The copolymerized polyethylene terephthalate containing 23% by weight of polyethylene glycol The copolymerized polyethylene terephthalate (B) acrylic rubber MAS Niacrylic KM-330 (ROHM & Co., Ltd.)
(manufactured by Haas) MBS: Metaprene C223 (manufactured by Mitsubishi Rayon) (C) Metal salt of a copolymer of α-olefin and α, β-unsaturated carboxylic acid Himilan 1707 (manufactured by DuPont Mitsui Polychemicals) (D) Glass fiber length 3, fiber diameter 10μIl (manufactured by Nittobo ■, C33J
941) (E) Polyethylene glycol Dekaball 0LE-1000, degree of polymerization 23 (Showa Kosan type) Examples 1 to 6, Comparative Examples 1 to 6 Polyethylene terephthalate, acrylic rubber, metal salt of copolymer, glass fiber, and polyethylene Mix the glycols in the proportions shown in the attached table, and use a two-wheel extractor to extract 270
The mixture was melted and kneaded at ℃ to form pellets.

Next, the obtained pellet was injection molded using an injection molding machine [manufactured by Sumitomo Heavy Industries ■, Sumitomo Neskool N515/150] at a cylinder temperature of 270°C and a mold temperature shown in the cough table to obtain a test piece. The moldability and physical properties were determined. The results are shown in the cough table.

Margins below [Effects of the Invention] The polyester resin composition of the present invention has a high crystallization rate even at relatively low temperatures, so it can be used economically at temperatures of 90 to 110°C, which are normally used for injection molding of general-purpose thermoplastic resins. In addition to having good moldability at low temperatures, such as being able to be molded well even at mold temperatures, the molded products have excellent rigidity and high impact strength, have good surface gloss, are lightweight, and can be molded at high temperatures. Because it has excellent dimensional stability and shape stability, as well as good heat resistance, it is suitably used as a molding material for, for example, automobile engine parts, electric tools, and connectors.

Claims (1)

[Claims] 1. (A) 100 parts by weight of polyethylene terephthalate, (B) 10 to 50 parts by weight of acrylic rubber, (C)
A polyester resin composition comprising 1 to 20 parts by weight of a metal salt of a copolymer of an α-olefin and an α,β-unsaturated carboxylic acid and 10 to 100 parts by weight of (D) a filler reinforcing substance.