JPH0774294B2 - Thermoplastic resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention provides a fiber-reinforced thermoplastic resin which is excellent in moisture absorption resistance and is suitable for obtaining a molded product having a low shrinkage ratio, a low linear expansion coefficient, and a surface gloss. It relates to a composition.

[Problems to be Solved by Prior Art and Invention]

Thermoplastic resin is easy to mold, so
It is used in large quantities in a wide range of fields, including packaging materials, industrial parts, and appliance parts. However, such a thermoplastic resin is not without its disadvantages. For example, since the difference between the specific volume of a thermoplastic resin when melted and the specific volume when it is solidified is large, it is inevitable that the resulting molded article will shrink more or less. Absent. Therefore, before designing a molded product, a mold is manufactured in consideration of the shrinkage ratio in advance.

On the other hand, in recent years, development of precision equipment such as communication equipment, OA equipment, audio equipment, and optical equipment has been remarkable. The dimensional accuracy (for long-term dimensional stability under various usage conditions) of the parts for precision instruments is severely required, and it is difficult to use a thermoplastic resin having a large shrinkage rate during molding.
Since the amorphous thermoplastic resin has a relatively small molding shrinkage, it is suitable for such a field, but is generally inferior in heat resistance. Further, such precision equipment parts have a problem of long-term dimensional stability under various usage conditions, and in particular, dimensional change due to moisture absorption in a high temperature and high humidity atmosphere. Therefore, such parts are usually manufactured by die casting or metal cutting.

The applicant of the present invention, as an amorphous thermoplastic resin having excellent heat resistance,
First, an ethylene / polycyclic olefin copolymer (JP-A-60-
168708 and JP-A-61-115916).
Such a thermoplastic resin is not only excellent in heat resistance, but also excellent in moisture absorption resistance, chemical resistance, solvent resistance, etc.,
A resin suitable as a molding material for parts of the precision equipment
Is one.

However, even such an ethylene / polycyclic olefin copolymer alone has a large molding shrinkage ratio, a linear expansion coefficient, etc., and cannot be used as it is for such parts. A method of adding a fibrous filler such as glass fiber as a modifier is known as one of means for reducing the molding shrinkage ratio,
The above publication also proposes to add and obtain a fibrous filler, but even if such a fibrous filler is simply added, improvement in molding shrinkage and the like is insufficient.

Therefore, the present inventor, based on ethylene, polycyclic olefin copolymer, as a result of various studies to improve molding shrinkage, linear expansion coefficient, etc., as a fibrous filler, glass fiber and potassium titanate fiber The inventors have found that the above properties can be improved by using them together in a specific ratio, and have completed the present invention.

[Means for solving problems]

That is, the present invention provides (A) a random copolymer of ethylene having an ethylene content of 40 to 90 mol% and a monomer component represented by the formula (1), wherein the monomer component is represented by the formula (2). 30-70% by weight of a random copolymer having a structure, (In the formula, R ^{1 to} R ¹² are hydrogen, an alkyl group or halogen, which may be the same or different, and further R ⁹ or R ¹⁰ and R
¹¹ or R ¹² may form a ring with each other. n is 0 or a positive number of 1 or more, and when R ^{5 to} R ⁸ are repeated a plurality of times, these may be the same or different. ) (B) 20 to 60% by weight of glass fiber, and (C) 5 to 20% by weight of potassium titanate fiber, which are excellent in surface gloss and moisture absorption resistance,
The present invention provides a thermoplastic resin composition suitable for obtaining a molded product having a low molding shrinkage and a low linear expansion coefficient.

[Work]

The random copolymer (A) used in the present invention is a random copolymer of ethylene having an ethylene content of 40 to 90 mol%, preferably 50 to 85 mol%, and a monomer component represented by the above formula (1). At the same time, the monomer component is a random copolymer having a structure represented by the formula (2).

Random copolymers having an ethylene content of more than 90 mol% have low heat resistance and are not suitable for applications such as precision equipment parts.

The random copolymer (A) used in the present invention preferably has an intrinsic viscosity [η] of 0.0 when measured at 135 ° C. in a decalin solvent.
3 to 10 dl / g, further 0.1 to 5 dl / g, crystallinity by X-ray diffraction is 10% or less, further 5% or less, iodine value is 5 or less, further 1 or less, glass transition temperature (Tg) 50 to 250 ℃, and even 6
It is in the range of 0 to 200 ° C.

Examples of the monomer component represented by the formula (1) used as the copolymerization component of the random copolymer (A) of the present invention include the following, but the examples shown here are extremely limited. Any of the compounds represented by the formula (1) can be the monomer component of the present invention.

Of these, n = 1 in formula (1), that is, formula (3), The monomer component represented by is preferable in terms of availability of the monomer or easy synthesis of the monomer. Furthermore, R ¹ ~
It is preferable that R ¹² is hydrogen in terms of heat resistance and solvent resistance.

To prepare the above-mentioned monomer components, for example, US Patent
3557072 (JP-B-46-14910) and JP-A-57-
The method of Japanese Patent No. 154133 can be applied.

The copolymer of the monomer component of the above formula (1) and ethylene may be copolymerized with another monomer component in an amount that does not impair the properties, for example, ethylene and less than an equimolar amount. Specific examples thereof include α-olefin, cyclic olefin, etc., and usually α having 3 to 20 carbon atoms, preferably 3 to 10 carbon atoms.
-Olefins such as propylene, 1-butene, 3-
Methyl-1-butene, 1-pentene, 3-methyl-1-
Pentene, 4-methyl-1-pentene, 1-hexene,
Examples thereof include 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-eicosene and the like. Cyclic olefins include cycloolefins and styrenes having no cross-linking, and examples thereof include cyclopentene, cyclohexene, 3,4-dimethylcyclopentene, 3-methylcyclohexene, 2- (2-methylbutyl) -1-cyclohexene, styrene and α-methylstyrene. Can be exemplified. Dicyclopentadiene, ethylidene norbornene, vinyl norbornene and other polyenes can be copolymerized in the same manner. Unsaturated carboxylic acids such as (anhydrous) maleic acid can also be copolymerized.

The polymer is produced by polymerizing using a well-known Ziegler catalyst, particularly a vanadium-based Ziegler catalyst. More specifically, it is disclosed in a prior patent application filed by the applicant (for example, JP-A-60-168708). A characteristic of the polymer is that the monomer component of the formula (1) mainly has a structure represented by the formula (2) in the polymer,
As a result, the iodine value of the polymer is usually 5 or less, and most is 1 or less. Moreover, ¹³ C-NMR confirms that this structure is adopted.

With this structure, the polymer is chemically stable, has excellent water resistance and chemical resistance to alkalis and acids, and further has excellent solvent resistance, heat resistance, and weather resistance. It also has an extremely low water content. It also has excellent dimensional accuracy.

The glass fiber (B) used in the present invention is used as a reinforcing material for a thermoplastic resin, and usually has a fiber diameter of 1
-20 μm, preferably 6-12 μm, fiber length 1-10 mm,
It is preferably in the range of 3 to 6 mm. The surface of the glass fiber (B) may be treated with a silane compound such as vinyltriethoxysilane, 2-aminopropyltriethoxysilane, 2-glycidoxypropyltrimethoxysilane.

The potassium titanate fiber (C) used in the present invention has the general formula
A fibrous crystal represented by K ₂ O · (TiO ₂ ) _n , usually having a fiber diameter of 0.1 to 3 μm, preferably 0.2 to 1 μm, and a fiber length of 5 to 100 μm, preferably 10 to 50 μm. is there.

The thermoplastic resin composition of the present invention comprises the random copolymer (A) 30 to 70% by weight, preferably 40 to 60% by weight, the glass fiber (B) 20 to 60% by weight, preferably 30 to 50% by weight. %
And 5 to 20% by weight, preferably 10 to 15% by weight, of the above-mentioned potassium titanate fiber (C).

If the glass fiber (B) is less than 20% by weight, the molding shrinkage and linear expansion coefficient are not improved, while if it exceeds 70% by weight, the appearance of the molded product tends to be poor.

If the potassium titanate fiber (C) is less than 5% by weight, the appearance of the molded article tends to be inferior. On the other hand, if it is 20% by weight or more, the amount of glass fiber used is limited.
The coefficient of linear expansion tends to be inferior.

The thermoplastic resin composition of the present invention includes the above (A) and (B).
In addition to the (C) component, the carbon fiber (D) is further added to 10 to 50
Addition of 10% by weight, preferably 10 to 30% by weight, improves the linear expansion coefficient and sliding characteristics of the molded product. The carbon fiber (D) used as such a reinforcing material usually has a fiber diameter of 3 to 20 μm.
m, preferably 7 to 18 μm, and the fiber length is 0.1 to 10 mm, preferably 0.3 to 3 mm.

In addition to the above components, the thermoplastic resin composition of the present invention contains an unsaturated carboxylic acid such as maleic anhydride in order to increase the affinity and adhesiveness between each fibrous reinforcing material and the random copolymer (A). Modified polyolefins graft-modified with an acid, such as ethylene-propylene copolymers, ethylene-butene copolymers, and random copolymers (A), which are the constituents of the present invention, are graft-modified with maleic anhydride or the like. You may add it.

The thermoplastic resin composition of the present invention, in addition to the above components,
Within the range that does not impair the object of the present invention, a heat stabilizer, a weather stabilizer, a lubricant, a nucleating agent, an antistatic agent, a dye, a pigment, an inorganic powder filler, (talc, calcium carbonate, wollastonite,
Mica, silica, etc. may be added in advance.

The thermoplastic resin composition of the present invention can be processed into various molded articles by various known molding methods such as injection molding, extrusion molding and compression molding.

〔The invention's effect〕

The thermoplastic resin composition of the present invention has good molding processability, and the obtained molded article has excellent moisture absorption resistance, heat resistance, surface gloss, low molding shrinkage, and low linear expansion coefficient. By injection molding, it is particularly suitable as a material for precision instrument parts such as compact discs, floppy disc drives, printer carriages, optical fiber connectors and their ferrules and sleeves, VTR guide rollers, and clock base plates. .

〔Example〕

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples as long as the gist thereof is not exceeded.

Reference example (Synthesis of ethylene polycyclic olefin copolymer) Ethylene and polycyclic olefin 1,4,5,8-dimethano- were continuously added using 2 glass polymerization reactors equipped with stirring blades.
1,2,3,4,4a, 5,8,8a-octahydronaphthalene The following is abbreviated as DMON). That is, from the top of the polymerization vessel, a cyclohexane solution of DMON, a DMON concentration in the polymerization vessel of 60 g / cyclohexane solution of VO (OC ₂ H ₅ ) Cl ₂ as a catalyst, and a vanadium concentration in the polymerization vessel of 0.9 m
mol /, ethyl aluminum sesquichloride (Al (C
₂ H ₅ ) _1.5 Cl _1.5 ) cyclohexane solution was continuously fed into each of the polymerization reactors so that the aluminum concentration in the polymerization reactor was 7.2 mmol / min. The polymerization liquid is continuously withdrawn so that it is always 1. Further, ethylene is fed at a rate of 85, hydrogen is fed at a rate of 6 per hour, and nitrogen is fed at a rate of 45 at an hour from the upper portion of the polymerization vessel. The copolymerization reaction was carried out at 10 ° C. by circulating a refrigerant through a jacket attached to the outside of the polymerization.

When the copolymerization reaction is performed under the above conditions, a polymerization reaction mixture containing an ethylene polycyclic olefin (ethylene / DMON) copolymer is obtained. A small amount of isopropyl alcohol was added to the polymerization liquid extracted from the lower part of the polymerization vessel to stop the polymerization reaction. Then, the polymerization solution was charged into a household mixer containing about 3 times the amount of acetone with respect to the polymerization solution while rotating the mixer to precipitate the produced copolymer. The precipitated copolymer was collected by filtration and the polymer concentration was about 50 g /
To the boiling point of acetone and treated the copolymer for about 2 hours. After the treatment described above, the copolymer was collected by filtration and dried under reduced pressure at 120 ° C. for 24 hours.

¹³ C-NMR of the ethylene / DMON random copolymer (ethylene polycyclic olefin copolymer) obtained as described above.
The ethylene composition in the copolymer measured by analysis was 59 mol%, 1
The intrinsic viscosity [η] measured in decalin at 35 ° C is 0.42dl / g,
The glass transition temperature was 136 ° C.

Example 1 Ethylene polycyclic olefin copolymer obtained in Reference Example: 50% by weight, glass fiber (diameter 13 μm, length 3 mm): 40% by weight and potassium titanate fiber (diameter 1 μm, length 20 to 50 μ): 10 After melt-kneading and granulating the weight% by a twin-screw extruder with a 45 mmφ vent (set temperature: 260 ° C.), the composition was injection-molded to obtain a test piece for physical property evaluation. The measuring method was as follows.

Appearance: The surface of the square plate for measuring the mold shrinkage was evaluated visually and visually.

◎: No gloss unevenness is observed on the surface and the front is smooth ○: The surface is not glossy but smooth ×: The surface is not glossy and gritty Molding shrinkage: 90 × 100 × 2mm square plate, Side gate. The shrinkage ratio was determined by measuring the size of the molded product with respect to the size of the mold.

Hygroscopic dimensional change: The square plate was left in an atmosphere of a temperature of 60 ° C. and a humidity of 90% for 250 hours to obtain a dimensional change.

Linear expansion coefficient: 12.7 × 127 × 3.2mm About 4 from the center of the test piece
A 6 × 3.2 mm test piece was cut out, the dimensional change due to temperature rise was measured, and the dimensional change rate in the region of 40 to 60 ° C. was obtained.

Bending strength: ASTM D 790 Bending elastic modulus: ASTM D 790 The measurement results are shown in Table 1. It can be seen from Table 1 that the molded products obtained from this composition are excellent in molding shrinkage, linear expansion coefficient, moisture absorption dimension change, and appearance, and are suitable for precision equipment parts.

Example 2 Instead of the composition used in Example 1, ethylene polycyclic polyolefin copolymer: 50% by weight, glass fiber: 20% by weight,
The procedure of Example 1 was repeated, except that a composition comprising 20% by weight of carbon fiber and 10% by weight of potassium titanate fiber was used. The results are shown in Table 1. It can be seen from Table 1 that the molded articles obtained from the composition are also excellent in molding shrinkage, linear expansion coefficient, moisture absorption dimension change, and appearance.

Example 3 With the formulation of Example 2, the mold temperature for injection molding was raised to 120 ° C. Further improvement in appearance (gloss) was observed from Example 2.

Comparative Example 1 Example 1 was repeated except that an ethylene polycyclic olefin copolymer was used alone instead of the composition used in Example 1. The results are shown in Table 1.

Comparative Example 2 The procedure of Example 1 was repeated, except that the composition used in Example 1 was replaced with a composition comprising ethylene polycyclic olefin copolymer: 50% by weight and glass fiber: 50% by weight. The results are shown in Table 1.

Comparative Example 3 Instead of the composition used in Example 1, ethylene polycyclic polyolefin copolymer: 50% by weight, carbon fiber (pitch-based,
The procedure of Example 1 was repeated, except that a composition having a diameter of 18 μm and a length of 0.37 mm): 50% by weight was used. The results are shown in Table 1.

Comparative Example 4 Instead of the composition used in Example 1, ethylene polycyclic polyolefin copolymer: 50% by weight, potassium titanate fiber: 50
The procedure was as in Example 1, except that a composition consisting of wt.% Was used. The results are shown in Table 1.

Claims (1)

[Claims] 1. A random copolymer of (A) ethylene having an ethylene content of 40 to 90 mol% and a monomer component represented by the formula (1), wherein the monomer component is represented by the formula (2). 30-70% by weight of a random copolymer having a structure, (In the formula, R ^{1 to} R ¹² are hydrogen, an alkyl group or halogen, which may be the same or different, and further R ⁹ or R ¹⁰ and R
¹¹ or R ¹² may form a ring with each other. n is 0 or a positive number of 1 or more, and when R ^{5 to} R ⁸ are repeated a plurality of times, these may be the same or different. ) A thermoplastic resin composition comprising (B) 20 to 60% by weight of glass fiber and (C) 5 to 20% by weight of potassium titanate fiber.