JPH0635532B2 - Polyethylene terephthalate composition - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyethylene terephthalate composition for injection molding which has low heat shrinkability.

Polyethylene terephthalate is widely used in the fields of fibers, films, bottles, etc. by taking advantage of its excellent properties, but in the field of injection molding, it has the potential to be an extremely excellent molding material. Nevertheless, it has not been used that much. This is because the crystallization rate of polyethylene terephthalate at a low temperature is slow, so that it is not possible to achieve sufficient crystallization at a normal mold temperature (100 ° C or less) of a general thermoplastic resin, and when a molded product is heated, a part of Is caused by shrinkage due to recrystallization and is significantly deformed. Therefore, conventionally, the mold temperature is increased to 150 ° C. or higher, or a nucleating agent or a crystallization accelerator is added to increase the crystallinity and reduce the heat shrinkage at high temperature.

However, raising the mold temperature not only raises the cost of equipment and energy, but also lengthens the molding cycle and significantly impairs the economical efficiency. Also, in order to achieve sufficient effects with the use of nucleating agents and crystallization accelerators, it is necessary to add a large amount of relatively low molecular weight substances, which causes smoke and odor during molding, which may worsen the working environment. However, there are drawbacks such that the additive exudes on the surface of the product and the mechanical strength is lowered.

The present inventors have earnestly studied to provide a polyethylene terephthalate composition that does not have the above-mentioned drawbacks and does not require a particularly high mold temperature, and as a result, the heat shrinkability without increasing the crystallization rate that has been conventionally considered. The composition disclosed in Japanese Patent Application No. 59-115503 was previously proposed, whereby the heat shrinkage of the polyethylene terephthalate resin was certainly compounded with a crystal nucleating agent or a crystal promoter. Improved without doing.

However, further studies have revealed that increasing the compounding amount of the thermoplastic elastomer to reduce the heat shrinkage tends to worsen the heat shrinkage. Therefore, as a result of further in-depth studies, the present inventors have found a technique in which such heat shrinkage hardly occurs, and completed the present invention.

(Outline of the present invention) That is, the present invention, as the component (A), with respect to 100 parts by weight of polyethylene terephthalate resin, as the component (B), from 20 to 250 parts by weight of the reinforcing filler (C), from room temperature Coefficient of linear expansion 12 × 1 in the range of 120 ℃
0 ^-5 cm / cm / ℃ or more polyolefin resins 10-60
By weight, as component (D), 0.05 to 4 parts by weight of an organic carboxylic acid salt of a metal selected from Group 1a and Group 2a of the Periodic Table is blended, and the component (C) is contained in the blend. A polyethylene terephthalate resin composition in which a polyolefin resin is dispersed with an average particle size of 1 to 20 μm.

(Specific Description of the Present Invention) Hereinafter, details of the present invention will be described.

The polyethylene terephthalate resin which is the basic component (A) of the composition of the present invention is a polyester comprising ethylene glycol and terephthalic acid at least 80 mol%, preferably 90 mol% or more of ethylene glycol and terephthalic acid. Further, other acid component and glycol component may be copolymerized within a range that does not impair the crystallinity. Dicarboxylic acids such as isophthalic acid, naphthalenedicarboxylic acid, adipic acid, sebacic acid and cyclohexanedicarboxylic acid as the acid component, and trimethylene glycol, tetramethylene glycol, hexamethylene glycol, polyethylene glycol, polypropylene glycol, polyethylene and polypropylene as the glycol component. Examples thereof include copolymers of glycol. Polyethylene terephthalate has an intrinsic viscosity of 0. 0 measured at 30 ° C in a 1: 1 weight ratio mixed solvent of phenol and tetrachloroethane.
It is 3 or more, preferably 0.5 or more, and is produced by a melt polycondensation reaction or a combination thereof with a solid phase polymerization reaction.

In the present invention, the reinforcing filler as the component (B) to be blended with the polyethylene terephthalate is a fibrous or granular inorganic substance or organic substance. Examples of the fibrous reinforcing filler include glass fiber, shirasu glass fiber, alumina fiber, silicon carbide fiber, ceramic fiber, asbestos fiber, gypsum fiber, stainless fiber, carbon fiber and Kevlar fiber. Further, as granular reinforcing filler, wollastonite, sericite, kaolin, mica, clay, pentonite, asbestos, talc, silicates such as alumina silicate, alumina, silicon oxide, magnesium oxide, zirconium oxide, titanium oxide, etc. Metal oxides of
In addition to carbonates such as calcium carbonate, magnesium carbonate and dolomite, and sulfates such as calcium sulfate and barium sulfate, glass beads, glass flakes, boron nitride, silicon carbide, saloyan and the like can be mentioned. One kind or two or more kinds of these reinforcing fillers are used. If necessary, the above-mentioned reinforcing filler may be pretreated with a silane-based or titanium-based coupling agent before use. The amount of these reinforcing fillers mixed with the polyethylene terephthalate resin is 2
It is 0 to 250% by weight, preferably 35 to 200% by weight. If the blending amount is 20 parts by weight or less, the effect of the present invention will not be exhibited, and if it is 250 parts by weight or more, the fluidity of the composition of the present invention during molding is poor, which is not practical.

The polyolefin resin as the component (C) is a polymer obtained by polymerizing one or more olefins, and the temperature is from room temperature to 12
The coefficient of linear expansion in the range of 0 ° C. is 12 × 10 ⁻⁵ cm / cm / ° C. or more. Specific examples include polyethylene, polypropylene, ethylene-propylene copolymer, ethylene
4-Methylpentene-1 copolymer, propylene / butene-1 copolymer and the like, but polypropylene and ethylene / propylene block copolymer are particularly preferable. The polyolefin resin basically has poor compatibility with the polyethylene terephthalate resin which is the component (A), and has an average particle size of 1 to 20 μm and is dispersed in a matrix composed of the polyethylene terephthalate resin and a reinforcing filler. It is necessary to have The average particle diameter referred to herein is the weight average particle diameter of the dispersed polyolefin resin, and is measured by a scanning electron microscope. If the dispersion diameter is 1 μm or less, the effect of the present invention does not appear, and if it is 20 μm or more, the mechanical strength of the composition of the present invention decreases. Therefore, as the polyolefin resin, a copolymer of the above-mentioned olefin monomer and a polar monomer, for example, ethylene / vinyl acetate copolymer, ethylene / acrylic acid copolymer, ethylene / vinyl acetate / glycidyl methacrylate is used. Polyolefin resins having good compatibility with reinforced polyethylene terephthalate resins such as copolymers and propylene / maleic anhydride glast copolymers do not exhibit the effects of the present invention.

The amount of the polyolefin resin to be blended is 10 to 100 parts by weight of the polyethylene terephthalate resin which is the component (A).
60 parts by weight, preferably 15 to 50 parts by weight. When the blending amount is 10 parts by weight or less, the effect of the present invention is not exhibited,
If it is more than 60 parts by weight, the mechanical strength of the composition of the present invention is remarkably reduced and thermal expansion occurs.

The organic carboxylate of a metal selected from Group 1a and Group 2a of the periodic table as the component (D) has a carbon number of 2 to 3
3 aliphatic, aromatic carboxylic acids, such as lauric acid,
Stearic acid, montanic acid, oleic acid, arachidic acid,
Carnauba acid, lignoceric acid, cerotic acid, betroseric acid, erucic acid, linoleic acid, benzoic acid and terephthalic acid salts are used.

Moreover, what saponified the copolymerization of (meth) acrylic acid or its ester, and ethylene etc. can be used.

Examples of the metal species include lithium, sodium, potassium, barium, magnesium, calcium and strontium. Examples of particularly preferred organic carboxylates include sodium stearate, potassium stearate,
Examples thereof include calcium montanate, sodium erucate, sodium benzoate, and a partially neutralized sodium salt of an ethylene / methacrylic acid copolymer. The amount of the organic carboxylate compounded is 0.05 to 4 parts by weight, preferably 0.1 to 3 parts by weight, based on 100 parts by weight of the component (A). If it is less than 0.05 parts by weight, the effect of the present invention will not be exhibited, and if it is more than 4 parts by weight, the mechanical properties of the composition of the present invention will be significantly reduced.

In the present invention, the reason why the heat shrinkage of the polyethylene terephthalate composition is remarkably improved is not clear, but the heat shrinkage of the reinforced polyethylene terephthalate composition and the heat expansion of the polyolefin resin dispersed in the composition of the present invention in an appropriate size. It is presumed that this is because the reinforced polyethylene terephthalate matrix having a high flexural modulus containing a large amount of the reinforced filler and exhibiting an offset balance and having an extremely low linear expansion coefficient after being recrystallized.

In the composition of the present invention, in addition to various compounding agents such as flame retardants, antioxidants, ultraviolet absorbers, colorants / pigments, crystal nucleating agents / accelerators, etc. within a range that does not impair the object of the present invention. Other thermoplastics such as, for example, polyethylene terephthalate,
Polycarbonate, polyamide, polyphenylene ether, polyphenylene sulfide, polystyrene, AB
S resin and the like can be blended.

The composition of the present invention, components (A), (B), (C), after each dry blending (D), a usual melt-kneading technique, for example, an extruder,
It can be easily manufactured with a kneader or a Banbury mixer.

As means for dispersing the average particle size of the polyolefin resin dispersed in the composition of the present invention within the range of 1 to 20 μm,
The following methods can be adopted to achieve the purpose.

(A) The resin is selected so that the viscosity ratio of the polyethylene terephthalate resin and the polyolefin resin under the melt-kneading condition is within a predetermined range.

(B) Select melt-kneading conditions (temperature, screw shear rate of kneader, screw dimension, etc.).

Generally speaking, as the viscosity ratio of both resins under the melt-kneading condition approaches 1, the compatibility improves and the average particle size decreases.

(Examples and Comparative Examples) Examples and comparative examples of the present invention will be described below, but the present invention is not limited to the following examples.

Examples 1 to 10 and Comparative Examples 1 to 11 Polyethylene terephthalate (Kuraray Co., Ltd., 1: 1 weight ratio mixed solvent of phenol and tetrachloroethane, 30)
℃, intrinsic viscosity 0.68) and as a reinforcing filler, glass fiber (CS03JA416 made by Asahi Fiber Co., Ltd.), mica (Kuraray Co., Ltd., 200HK), various polyolefins, sodium stearate, potassium benzoate in the proportion of Table-1, A 40 mm, single screw extruder was melt-kneaded at once at 260 ° C. to obtain a pellet. The pellets obtained are 130 ° C., 5
After drying with a hot air dryer for 5 hours, with a 5 ounce injection molding machine,
Sheet for heat shrinkage evaluation at mold temperature of 80 ° C (100 x 8
0 × 2 mm) and a flexural modulus measuring sample was obtained.

The heat shrinkage rate is indicated by the dimensional change in the direction (TD) perpendicular to the sheet flow direction after heat treating the obtained sheet in air at 120 ° C. for 1 day.

Further, the thermal shrinkage in the MD direction was also obtained by the following equation.

Comparative Example 12 Example 3 except that the temperature of the melt-kneading was changed to 280 ° C.
I went the same way. The results are shown in Table-2.

Comparative Example 13 Ethylene / Propylene Copolymer, Mitsubishi Petrochemical Co., Ltd., Mitsubishi Polypro (former name: Mitsubishi Noblen) BC8Q (melt flow rate: 230 ° C, load 1.2 g / 10, 2.16 kg load)
Min) instead of Mitsubishi Yuka, Mitsubishi Polypro BC08C
(Melt flow rate: 230g, 95g at 2.16kg load)
/ 10 minutes) was used, and the same procedure as in Example 3 was performed.
The results are shown in Table-2.

From the results shown in Table-1, it is recognized that the composition of the present invention has an extremely small heat shrinkage even when molded at a low temperature mold temperature (80 ° C.) and is an excellent material.

Claims (1)

[Claims] 1. A composition comprising the following component (A), component (B), component (C) and component (D), wherein the average particle size of the polyolefin resin dispersed in the composition is 1 A polyethylene terephthalate composition that is ˜20 μm. Component (A): Polyethylene terephthalate resin 100 parts by weight (B) Component: Reinforcing filler 20 to 250 parts by weight (C) Component: Coefficient of linear expansion of 12 x 10 from room temperature to 120 ° C
^-5 cm / cm ° C or higher polyolefin resin 10-60
Parts by weight (D) component: Organic carboxylate of metal selected from Group a and Group a of the periodic table 0.05 to 4 parts by weight