JPH06136260A - Whisker-reinforced thermoplastic resin composition - Google Patents

Abstract

PURPOSE:To provide a whisker-reinforced thermoplastic resin composition causing little lowering of mechanical properties by moisture-absorption and having excellent abrasion resistance. CONSTITUTION:The composition causing little lowering of mechanical properties by moisture absorption, having remarkably small kinetic friction coefficient and, accordingly, exhibiting excellent abrasion resistance is produced by compounding amorphous nylon with whiskers.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a whisker-reinforced thermoplastic resin composition containing amorphous nylon as a main component, and particularly to a whisker-reinforced thermoplastic resin composition which has little deterioration in mechanical properties when absorbing moisture and is excellent in abrasion resistance. It relates to a plastic resin composition.

[0002]

BACKGROUND OF THE INVENTION Nylon (polyamide) is excellent in mechanical strength such as flexural strength, flexural modulus, impact resistance and scratch resistance, and especially nylon and glass fiber Since the above-mentioned physical properties are further improved by the reinforcing effect of the glass fiber, the composite material of (2) is widely used for small parts, thin-walled parts and products having complicated shapes.

However, since nylon has high hygroscopicity, there is a problem in that the mechanical strength of the above composite material is significantly lowered depending on the intended use, such as under high humidity conditions or when it is wet with water. Further, the composite material of nylon and glass fiber has a problem that the abrasion resistance is not sufficient.

Therefore, an object of the present invention is to provide a whisker-reinforced thermoplastic resin composition which has little deterioration in mechanical properties when absorbing moisture and is excellent in abrasion resistance.

[0005]

As a result of earnest research in view of the above objects, the present inventors have found that a composition containing amorphous nylon and whiskers has a decrease in mechanical properties when absorbing moisture. The present invention has been found out that it is small and the coefficient of kinetic friction is significantly small, and thus excellent wear resistance is exhibited.

That is, the whisker-reinforced thermoplastic resin composition of the present invention is characterized by containing 50 to 97% by weight of amorphous nylon and 3 to 50% by weight of whiskers.

The present invention is described in detail below. [1] Amorphous Nylon Examples of the amorphous nylon used in the present invention include amorphous polyamides described in JP-A-63-61040.

This amorphous nylon comprises (a) hexamethylenediamine and / or alkyl-substituted hexamethylenediamine, and (b) bis (4) having a substituent adjacent to an amino group.
-Amino-cyclohexyl) -methane derivative, (c) isophthalic acid or other aromatic or aliphatic dicarboxylic acid, and (d) terephthalic acid in the following blending ratios.

(A) Hexamethylenediamine and / or its alkyl-substituted derivative: 48-20 mol% (b) Bis (4-amino-cyclohexyl) -methane derivative:
2-30 mol% (c) Isophthalic acid or other aromatic or aliphatic dicarboxylic acid: 50-40 mol% (d) Terephthalic acid: 0-10 mol%

Of the above constituents, the alkyl-substituted derivative of hexamethylenediamine of component (a) is N, N '.
-Dimethylhexamethylenediamine, N, N'-dibenzoylhexamethylenediamine and the like can be mentioned.

Examples of the bis (4-amino-cyclohexyl) -methane derivative having a substituent adjacent to the amino group of the component (b) include bis (4-amino-3-methyl-5-ethylcyclohexyl) -methane. , Bis (4-amino-3,5-diethylcyclohexyl) -methane, bis (4-amino-3-methyl-5)
-Isopropylcyclohexyl) -methane, bis (4-amino-3,5-diisopropylcyclohexyl) -methane, bis
(4-amino-3,5-dimethylcyclohexyl) -methane, bis (4-amino-3-methylcyclohexyl) -methane, bis
(4-amino-3-ethylmethylcyclohexyl) -methane,
Alkyl-substituted diamines such as bis (4-amino-3-isopropylcyclohexyl) -methane or mixtures thereof. -CH ₂ in cyclohexane rings of these alkyl-substituted diamine - group ethylene, propylene, may be substituted by isopropylene or butylene.

Examples of aromatic or aliphatic dicarboxylic acids other than isophthalic acid as the component (c) include aromatic dicarboxylic acids such as orthophthalic acid, and aliphatic dicarboxylic acids such as oxalic acid, malonic acid, succinic acid and dodecanedicarboxylic acid. Is mentioned.

The above-mentioned amorphous nylon preferably has a glass transition point (Tg) of 120 to 190 ° C.

[2] Whiskers Whiskers are crystals of extremely fine ceramic single fibers called so-called whiskers, and examples thereof include potassium titanate whiskers, aluminum borate whiskers, calcium carbonate whiskers, magnesium hydroxide whiskers, and the like. . Of these, potassium titanate whiskers are particularly preferable.

Potassium titanate whiskers are generally K
₂ O · nTiO ₂ is represented by the chemical formula, 3.1
Preferably, it has a true specific gravity of .about.3.3, a bulk specific gravity of about 0.2, an average fiber length of 10 to 20 .mu.m and an average fiber diameter of 0.2 to 0.5 .mu.m.

The whiskers are preferably surface-treated with, for example, an epoxy-based silane coupling agent to enhance the affinity for amorphous nylon.

The blending ratio of the above-mentioned amorphous nylon and the whiskers is 50-97% by weight of amorphous nylon,
It is preferably 60 to 90% by weight, whiskers are 3 to 50% by weight, preferably 10 to 40% by weight. When amorphous nylon is less than 50% by weight (whiskers exceeding 50% by weight), moldability and friction properties are deteriorated, while when amorphous nylon exceeds 97% by weight (whiskers less than 3% by weight). ), The retention of mechanical strength when absorbing moisture decreases.

The whisker-reinforced thermoplastic resin composition of the present invention may further contain other additives for the purpose of modification.
For example, other inorganic fillers, heat stabilizers, antioxidants, light stabilizers, flame retardants, plasticizers, antistatic agents, release agents, nucleating agents and the like can be added.

The whisker-reinforced thermoplastic resin composition of the present invention can be produced by mixing the above-mentioned components and dynamically heat-treating, that is, melt-kneading. As the kneading device, conventionally known devices such as an open mixing roll, a non-open Banbury mixer, an extruder (including a twin screw), a kneader, and a continuous mixer can be used. Kneading is carried out at a temperature of 200 to 300 ° C, preferably 240 to 280
It may be performed at a temperature of ° C.

[0020]

Since the whisker-reinforced thermoplastic resin composition of the present invention contains amorphous nylon and whiskers, the mechanical properties of the molded article are not significantly deteriorated when absorbing moisture, and the dynamic friction coefficient of the molded article is extremely small. Therefore, it has good wear resistance.

Although the reason why such an effect is obtained is not always clear, amorphous nylon has a mechanical strength such as flexural strength, flexural modulus, impact resistance and scratch resistance, which are characteristics of nylon. It is considered that it is excellent, and further, the composition of the whisker and the synergistic effect of both are significantly reduced in the dynamic friction coefficient of the molded product obtained therefrom.

[0022]

The present invention will be described in more detail by the following specific examples. The following materials were used as the raw material resin and the whiskers in each example and comparative example. [1] Amorphous nylon AmNy: [Grivory XE-3038 manufactured by EMS,
Tg 140 ° C.] AmNy: [Gribory XE-3355 manufactured by EMS,
Tg 158 ° C.] [2] Nylon Ny6 [EMS Grylon A23] Ny66 [EMS Grylon T300] [3] Potassium titanate whiskers K ₂ TiO ₃ : [Otsuka Chemical Co., Ltd. Tismo D10]
2, average fiber length 10 to 20 μm, average fiber diameter 0.2 to 0.5 μ
m] K ₂ TiO _3: [Nippon whiskers Co. Tofika Y102, average fiber length 10 to 20 [mu] m, an average fiber diameter of 0.3 to 0.
5 μm] K ₂ TiO ₃ : [Tybrex manufactured by Kawatetsu Mining Co., Ltd., average fiber length 10 to 20 μm, average fiber diameter 0.2 to 0.5 μ
m] [4] Glass fiber GF: [03MAFT2A manufactured by Asahi Fiber Glass Co., Ltd., average fiber diameter 13 μm]

Examples 1 to 5 and Comparative Examples 1 to 4 Amorphous nylon (AmNy or AmNy) was kneaded by a 45 mmφ twin-screw extruder (L / D = 30) at 250 ° C. and 250 rpm. Potassium titanate whiskers (K ₂ TiO ₃ or later) in the mixing ratio shown in Table 1 from the middle of the axial extruder.
Was further supplied and kneaded to obtain pellets of the composition.

Using the obtained pellets, a test piece for a physical property test to be described later was prepared by injection molding, and the bending strength and its retention rate under dry conditions and hygroscopic conditions, and the dry strength and hygroscopic conditions were used. The flexural modulus and its retention, the dynamic friction coefficient and the specific wear amount were measured. The results are shown in Table 2.

Table 1 Composition (parts by weight) Example 1 Example 2 Example 3 Example 4 Example 5 AmNy 70 60 70 70 − AmNy − − − 70 K ₂ TiO ₃ 30 40 − − − K ₂ TiO ₃ − − 30 − − K ₂ TiO ₃ − − − 30 30

[0026] Table 1 (continued) Composition (parts by weight) Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 AmNy 100 70 - - Ny6 - - 70 - Ny66 - - - 70 K 2 TiO 3 - - 30 30 GF-30 ---

Table 2 Physical Properties Example 1 Example 2 Example 3 Example 4 Example 5 Bending Strength ⁽¹⁾ Dry 2100 2300 2000 2100 2100 Moisture Absorption 1600 1850 1540 1580 1600 Retention 76 80 77 75 76 Bend Elastic modulus ⁽²⁾ Dry 90000 110000 82000 90000 85000 Moisture absorption 81000 104000 74000 82000 77000 Retention 90 95 90 91 91 Dynamic friction coefficient ⁽³⁾ 0.35 0.31 0.36 0.34 0.34 Specific wear ⁽⁴⁾ 0.23 0.32 0.23 0.24 0.24

Table 2 (continued) Physical Properties Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Bending Strength ⁽¹⁾ Dry 1550 2400 2100 2200 Moisture Absorption 1250 1900 1200 1520 Retention 81 79 57 69 Flexural Modulus ⁽²⁾ Drying 34000 80000 81000 87000 When absorbing moisture 30000 73000 21000 29600 Retention rate 88 91 26 34 Dynamic friction coefficient ⁽³⁾ 0.55 0.59 0.62 0.64 Specific wear amount ⁽⁴⁾ 0.60 1.02 0.23 0.20

(1) Bending strength: ASTM D790 at 23 ° C
Drying and absorbing moisture (when the test piece is immersed in warm water at 40 ° C to absorb water up to 50% RH saturated moisture absorption)
The bending strength (unit: kg / cm ² ) of each of the samples was measured, and the retention rate (unit:%) was calculated. (2) Flexural modulus: The flexural modulus under dry and hygroscopic conditions (unit: kg / cm ² ) as in (1) above.
Was measured and the retention rate (unit:%) was calculated. (3) Dynamic friction coefficient: JIS K7218 (load 10kgf, peripheral speed 30mm /
sec, mating material S45C) (unit: μ). (4) Specific wear amount: Measured according to JIS K7218 (Unit: mm ³
/ Kgf ・ km).

As is apparent from Table 2, Examples 1-5
The composition of (1) had a high flexural strength and flexural modulus retention upon moisture absorption, and had a low dynamic friction coefficient and a small specific wear amount. On the other hand, the whisker-reinforced thermoplastic resin compositions of Comparative Examples 3 and 4 using ordinary nylon have low flexural strength and flexural modulus retention upon absorption of moisture, and amorphous nylon contains glass fiber. The composition of Comparative Example 2 blended had a large specific wear amount.

[0031]

As described in detail above, since the whisker-reinforced thermoplastic resin composition of the present invention contains amorphous nylon and whiskers, the mechanical properties of the whisker are not significantly deteriorated when absorbing moisture. The molded product has a small dynamic friction coefficient and excellent wear resistance. The whisker-reinforced thermoplastic resin composition of the present invention as described above is suitable as a material for small machine parts, gears, rollers and the like.

Claims (1)

[Claims] 1. A whisker-reinforced thermoplastic resin composition comprising 50 to 97% by weight of amorphous nylon and 3 to 50% by weight of whiskers.