JPH0428768A - Thermoplastic resin composition - Google Patents

Abstract

PURPOSE:To obtain a thermoplastic resin composition having excellent heat resistance, stiffness and dimensional stability, suitable for car component and electric and electronic parts by dispersing a liquid crystal resin into a continuous phase of thermoplastic resin in grain form having a proper grain size. CONSTITUTION:The objective thermoplastic resin composition, obtained by melting and kneading (A) 60-95wt.%, preferably 70-90wt.% thermoplastic resin composition (preferably polyethylene terephthalate, polybutylene terephthalate, high-density polyethylene or polypropylene) with (B) 5-40wt.%, preferably 10-30wt.% resin (e.g. polyester consisting of ethylene glycol, terephthalic acid and 4-hydroxybenzoic acid) capable of forming anisotropic melting phase, in which the component B is dispersed in a grain-like form having 5-50, preferably 10-40mum average grain size.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a thermoplastic resin composition. Various thermoplastic resins are widely used in the fields of automobile parts and electrical and electronic parts, but in mechanical parts etc.
Further improvements in heat resistance, rigidity, and dimensional stability are desired. The present invention provides a molding material with improved heat resistance, rigidity, and dimensional stability that is suitable for such uses.

[Conventional technology]

It is well known that glass fibers and carbon fibers are added to thermoplastic resins to improve their heat resistance, rigidity, and dimensional stability, but adding fibrous fillers not only reduces moldability but also reduces moldability. , the appearance of the molded product is impaired.

On the other hand, resins that can form an anisotropic melt phase (hereinafter sometimes referred to as liquid crystal resins) are materials with extremely excellent rigidity, heat resistance, etc. A fiber with improved strength and modulus of elasticity is disclosed in which a fibrous liquid crystalline resin is dispersed in a resin. Japanese Unexamined Patent Publication 1987-
No. 51739 discloses that by blending polyphenylene sulfide with a liquid crystal resin, it provides a material that does not significantly impair the mechanical properties of the liquid crystal resin, is cheaper than the liquid crystal resin, and improves the moldability of polyphenylene sulfide. The effects of this are described. Japanese Patent Publication No. 125265
No. 7 discloses a method of improving heat resistance etc. by adding a thermoplastic resin to a liquid crystal resin. However, none of these techniques suggests a specific technique for achieving the maximum reinforcing effect by adding a small amount of liquid crystal resin that does not impair the desirable properties of the base thermoplastic resin.

[Problem to be solved by the invention]

By blending liquid crystal resin with thermoplastic resin, it achieves heat resistance, rigidity,
When attempting to improve dimensional stability, blending a large amount of liquid crystalline resin tends to increase these reinforcing effects, but often also increases unfavorable properties such as a decrease in impact strength and strength anisotropy.

Therefore, the present inventors conducted studies to find a method of maximizing the above-mentioned reinforcing effect by blending a relatively small amount of liquid crystalline resin.

[Means to solve the problem]

The present invention comprises a thermoplastic resin (A) in an amount of 60 to 95% by weight, and a resin (liquid crystalline resin) (B) capable of forming an anisotropic melt phase.
A composition comprising 40 to 5% by weight of component (B).
) is dispersed in the form of particles with an average particle size of 5 to 50 microns. The constituent components will be explained below.

1 Plastic A The present invention effectively improves the heat resistance, rigidity, and dimensional stability of known molding resin materials. Therefore, as long as the thermoplastic resin has the above-mentioned unachieved performance requirements, crystalline resins such as polyethylene terephthalate, polyethylene terephthalate, polyamide 6, polyamide-6,6, polyphenylene sulfide, polyethylene, polypropylene, etc. Resins are preferred. It is also preferable to use a mixture of the above crystalline resin and a non-grade resin such as polycarbonate, polystyrene, polyphenylene ether, polyvinyl chloride. Particularly preferred resins are polyethylene terephthalate, polybutylene terephthalate, high density polyethylene, and polypropylene.

Resin capable of forming anisotropic melt phase (B) The resin capable of forming an anisotropic melt phase used in the present invention is well known as a so-called liquid crystal resin. Confirmation of the anisotropic melt phase can be performed by observing a sample in a molten state using a polarizing microscope. That is, under the orthogonal conditions of the polarizer and analyzer, it is recognized that light is transmitted due to optical anisotropy.

The general structure of liquid crystal resin is a semi-aromatic polyester consisting of an aliphatic diol, an aromatic dicarboxylic acid, and an aromatic hydroxycarboxylic acid, an aromatic diol and an aromatic dicarboxylic acid, or an aromatic diol and an aromatic dicarboxylic acid. A wholly aromatic polyester consisting of an aromatic hydroxycarboxylic acid or only an aromatic hydroxycarboxylic acid is known. Here, examples of aliphatic diols include ethylene glycol, 1,3-propylene glycol, 1,4-butene glycol, 1.6-hexene glycol, and 1,12-dodecamethylene glycol; examples of aromatic diols include For example, 1,4- or 1,3-dihydroxybenzene, 4.4' or 3.3
'-dihydroxydiphenyl, 2,2-bis(4'-hydroxyphenyl)propane, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxydiphenyl sulfide, 1,4 -dihydroxynaphthalene, 2.6-
Aromatic dicarboxylic acids such as dihydroxynaphthalene and 1.6 dihydroxynaphthalene include terephthalic acid, isophthalic acid, diphenyl-44'-dicarboxylic acid, naphthalene-1,4-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, and cyphenyl. Examples of aromatic hydroxycarboxylic acids include sulfone-4,4'-dicarphonic acid, nphenyl ether-4,4'-dicarboxylic acid, and 4-hydroquine 7! +, aromatic acid, 4-hydroxydiphenyl-4-
Examples include carboxylic acid, 2-hydroxy-6-naphthoic acid, 1-hydroxy-4-naphthoic acid, and the like.

Note that the benzene ring and naphthalene ring may be substituted with a lower alkyl group, an aryl group, or a halogen group.

Specific examples of component (C) used in the present invention include polyesters consisting of ethylene glycol, terephthalic acid and 4-hydroxybenzoic acid, and polyesters consisting of 1,4-dihydroxybenzene, terephthalic acid and 4-hydroxybenzoic acid. , polyester consisting of 4,4'-dihydroxydiphenyl and terephthalic acid and 4-hydroxybenzoic acid, polyester consisting of 4,4'-dihydroxydiphenyl and isophthalic acid and 4-hydroxybenzoic acid, 2-hydroxy-6-naphthoate Typical examples include polyester made of an acid and 4-hydroxybenzoic acid. These include, for example, rX-7Gj from Eastman, [Tubaculate] from Mitsubishi Kasei, and [Rodrun] from Unitika.
Idemitsu LCP from Idemitsu Petrochemicals, Dartco, Xider from Nissui Petrochemicals, Econol from Sumikata Chemical, Vectra from Hoechst Celanese and Polyplastics, and ICI Japan. Each is commercially available under the trade name ``Pictrex''.

The composition of the present invention is characterized in that a liquid crystalline resin is dispersed in a continuous phase of a thermoplastic resin in the form of particles with an appropriate particle size. Particle size can be determined as follows. Optical microscopes such as phase contrast microscopes, polarizing microscopes, and differential interference microscopes,
From the micrographs observed using a scanning electron microscope,
A region is defined so that the number of dispersed particles is 200 or more, and the area-equivalent circular diameter of each particle is measured. A commercially available image analysis device can be used to measure the particle size. The volume average diameter is calculated from the equivalent circular diameter of each particle image obtained, and is taken as the average particle diameter.

The average particle size is from 0 to 50 microns, preferably from 10 to 40 microns. If the average particle diameter is less than 5 microns, the effect of improving heat resistance, rigidity, and dimensional stability is small. If the average particle diameter exceeds 50 microns, orientation during molding becomes significant, which may cause layer peeling, resulting in poor appearance and reduced strength. Generally, in the technical field of polymer blends, the aim is to increase the reinforcing effect by making the dispersed particle size finer, whereas in the structure of the composition of the present invention, there is a lower limit of the preferred particle size on the order of microns.

Component (A) 60 to 95% by weight of a thermoplastic resin, preferably 70 to 90% by weight, and component (B) a resin capable of forming an anisotropic melt phase, 5 to 40% by weight, preferably 10% by weight. and 30% by weight. Component (B) is 5% by weight
If it is less than 40% by weight, the effect of improving heat resistance, rigidity, and dimensional stability is small, and if it exceeds 40% by weight, these effects tend to increase, but unfavorable properties such as strength anisotropy and decrease in impact strength occur. Authored in order.

Flame q The composition of the present invention can be produced by melt-kneading using rolls, a Banbury mixer shaft, a twin-screw kneader, or the like, within a temperature range in which the liquid crystalline resin used can form an anisotropic melt phase. To control the particle size of the dispersed phase, the viscosity ratio of both components,
This can be achieved by appropriately selecting factors known to those skilled in the art regarding the affinity of both components. The particle size becomes finer as the viscosity ratio of both components approaches 1, which is determined under shear rate conditions close to the crosstalk conditions. Furthermore, the better the affinity between the two components, the smaller the dispersed particle size. Furthermore, a so-called compatibilizer can be used to adjust the affinity. A compatibilizer is a third additive that has affinity for both two incompatible components, which is well known in the technical field of polymer alloys, and is a graft copolymer that has partial chains of both components. Copolymer and Pro-Nc copolymers are commonly used. It is also possible to control the dispersed particle size by the mixing method. Generally, the greater the shear history, the smaller the particle size.

[Examples] Table 1 shows the compositions of Examples and Comparative Examples. The composition was manufactured by mixing a predetermined mixture using a PCM twin-screw extruder manufactured by Ikegai Tekko Co., Ltd. at a temperature approximately 20"C higher than the melting point of the liquid crystal resin, and then cooling with water to obtain pellets. 120
After drying for 12 hours in a vacuum dryer set at .degree. C., predetermined test pieces were prepared using an M40 A-S, J-type injection molding machine manufactured by Mei Seisakusho Co., Ltd. The molding temperature was set at a temperature 20° C. higher than the melting point of the liquid crystal resin.

The bending elastic modulus is 23° according to JIS K7203.
Measured at C. The heat distortion temperature was measured under a load of 4.6 kg in accordance with JIS K7110. The coefficient of linear expansion is ^STM
Using a commercially available quartz tube dilatometer made in accordance with D696-79, a test piece with a length of 90 mm, a width of 10 mm, and a thickness of 4 mm was heat treated at 120°C for 11 hours, and then the temperature was increased to 30°C. Measurements were made within a range of 80°C.

The dispersed particle size of the liquid crystalline resin was determined by cutting out a portion of a test piece compression-molded from a pellet, preparing a sample for electron microscopy observation using a microtome, and etching it using an ion etching device at a reduced pressure of 0.9 Torr and an etching time of 10 minutes. After ion etching under the following conditions, a photograph of the dispersed particle size was taken using a scanning electronic microscope (Akashi Separation MSM-9). Measuring the particle diameter on the photograph The measurement area was set so that the number of particle images exceeded 200, and the area-equivalent circle diameter was measured using an image analysis device (5PICCΔ■ manufactured by Nippon Avionics Co., Ltd.).
Create a histogram with intervals of 0.5 microns.

The average particle diameter was evaluated based on the volume average particle diameter calculated by D-ΣiD i'/ΣniD i3 (number of particles ni belonging to the representative value Di of the histogram).

The evaluation results for each composition in Table 1 are shown in Table 2.

Table 1 (Composition) 1> Polypropylene Mitsubishi Yuka Co., Ltd. "Mitsubishi Polypro MA8.1 Melt flow rate 1, Oy/1 min, 2) Liquid crystalline resin manufactured by Vectra Polyplastics [Vectra A9 O"] 3) Polyamide -6: Mitsubishi Kasei Corporation “Tubamint 1”
040J, 4) Polyethylene terephthalate tote, Nippon Unipet r
RT580cA'', 5) Polypropylene modified with polymer, prototype, melt flow rate lo, 5 g/10 min, content of vinyl trime I-xysilane 2.6% by weight.

/ / / /′ / Table 2 (results) Evaluation was performed after heat treatment at 120°C for 1 hour after main molding.

〔Effect of the invention〕

From the results in Table 2, it is clear that the reinforcing effect of the liquid crystal resin dispersed with an average particle size of 5 to 50 microns is remarkable even when 10 parts by weight is added, and increases as the amount is increased. The thermoplastic resin composition of the present invention has heat resistance and rigidity,
The present invention presents a desirable composition for mechanical parts used in high-temperature operating environments that require dimensional stability.

Special permission Out wish Man Mitsubishi Yuka Co., Ltd.

Claims (1)

[Claims] The thermoplastic resin (A) is composed of 60 to 95% by weight, and the resin (B) capable of forming an anisotropic melt phase is composed of 40 to 5% by weight, and the resin (B) capable of forming an anisotropic melt phase has an average A thermoplastic resin composition characterized in that it is dispersed in the form of particles with a particle size of 5 to 50 microns.