JPH0726139A - Thermoplastic resin composition having wear resistance - Google Patents

Abstract

PURPOSE:To obtain a thermoplastic resin composition useful for mechanical parts, etc., as a resin-based sliding material, having excellent wear resistance, heat resistance and moldability by blending a thermoplastic polyamide-imide resin having a specific structure with graphite in a prescribed ratio. CONSTITUTION:The resin composition comprises (A) 90-70wt.% of a thermoplastic polyamide-imide resin, a random copolymer of the formula [(l), (m) and (n) are molar ratios respectively, (l):(m+n) is 5:95-30:70 and (m):(n) is 5:5-9:1] having 10,000-300,000 molecular weight and (B) 10-30wt.% of graphite.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel thermoplastic resin composition having excellent wear resistance, heat resistance and moldability. The product of the present invention can be applied to machine parts and the like as a resin-based sliding material.

[0002]

2. Description of the Related Art Graphite, polyimide resin, and polytetrafluoroethylene resin are known as resin-based sliding materials having high heat resistance, but all of these materials require high temperature and high pressure for molding, which makes molding difficult. Is. On the other hand, polyamide-imide resin, polyetherimide resin, polyamide resin, polyacetal resin, etc. are known as resin-based sliding materials which can be molded by a highly productive injection molding method and have relatively high heat resistance. All have limited heat resistance and are difficult to apply to mechanical parts that require high heat resistance.

In addition, fine particles of graphite, molybdenum disulfide, polytetrafluoroethylene resin or the like are generally blended as fillers in resin-based sliding materials for the purpose of improving wear resistance. When these fillers are blended with the resin, the wear resistance is improved, but the heat resistance depends on the resin as the base (base), and therefore, a significant improvement cannot be expected. Further, the wear resistance is improved as the blending amount of the filler with respect to the resin is increased, but conversely, the moldability and the mechanical strength of the molded product are deteriorated, so that the blending amount of the filler is limited.

[0004]

The resin-based sliding material that can be injection-molded as described above has a limit in heat resistance, and in the method of incorporating a filler, the moldability and the mechanical strength of the molded body are not improved. Therefore, there is a problem in that the blending amount of the filler is limited, and a significant improvement in heat resistance cannot be expected. An object of the present invention is to provide a novel thermoplastic resin composition that overcomes the above-mentioned problems and is excellent in wear resistance, heat resistance, moldability, and mechanical strength.

[0005]

The present invention has solved the above problems by blending graphite fine particles in a specific ratio with a specific polyamide-imide resin. That is, the present invention has the following general formula (I)

[Chemical 2] [However, in the general formula (I), l, m, and n each represent a molar ratio, and l: (m + n) is 5:95 to 30:70.
And m: n is in the range of 5: 5 to 9: 1], which is a random copolymer having a molecular weight of 10,000 to 300,000 and is a thermoplastic polyamide-imide resin 90.
Provided is a thermoplastic resin composition having an abrasion resistance of 70% by weight to 10% by weight of graphite.

[0006]

The polyamideimide resin represented by the above general formula (I) has already been proposed by the present inventors as a polyamideimide resin having a novel chemical structure in 1991 Patent Application No. 182617.
The following general formula (1a)

[Chemical 3] And the following general formula (1b)

[Chemical 4] A structural unit represented by the general formula (1a) and (1
In b), Z represents a trivalent aromatic residue containing at least one carbon 6-membered ring, Ar represents a divalent aromatic residue, and p and q each represent the number of moles], but p: q = 3: 97 to 80:
Molecular weight of 10,000 to 1 linearly irregularly arranged at a molar ratio of 20
It is a further improvement of 0,000 aromatic polyamideimides. The melting temperature of the polyamide-imide resin of the general formula (I) of the present invention is 380 to 390 ° C., and the resin viscosity is 1 × 10 ^6.
The value is poise (380 ° C., γ = 10 sec ⁻¹ ). This improved resin was melt-moldable, and the molded product had a high heat resistance with a glass transition temperature of 290 ° C. Based on the polyamide-imide resin, the composition of the present invention can improve wear resistance by blending graphite while maintaining its moldability, mechanical strength and heat resistance. As a result of various studies on graphite, molybdenum disulfide, tequilafluoroethylene resin and the like as a filler, the present inventors have found that blending graphite is the most effective.

The resin composition of the present invention comprises a thermoplastic resin represented by the general formula (I) and graphite. The ratio of the polyamideimide resin (A) and the graphite (B) in the thermoplastic resin composition of the present invention is (A) :( B) = 90: 10 to 70:
The range of 30 is preferable, and if the amount of graphite blended with the resin composition is less than 10% by weight, the effect of improving the wear resistance by blending graphite is insufficient and sufficient wear resistance cannot be obtained.
On the other hand, if it exceeds 30% by weight, the melt viscosity of the resin becomes extremely high, which makes not only molding difficult but also the strength of the molded product is significantly lowered.

Further, the resin composition comprising the polyamideimide resin of the present invention and graphite may be a thermoplastic resin composition containing 10 to 30% by weight of reinforcing fibers such as carbon fibers and aramid fibers depending on the application. Alternatively, it may be a thermoplastic resin composition containing 10 to 30% by weight of fine particles such as molybdenum disulfide and polytetrafluoroethylene resin.

The polyamide-imide resin represented by the following general formula (I) of the present invention will be described in more detail. The polyamide-imide resin can be synthesized according to the method described in Japanese Patent Application No. 182617. General formula (I)

[Chemical 5] The polyamide-imide resin has the following general formula (II)

[Chemical 6] It is preferable that the aromatic diamine-based compound represented by is contained as a polymer component in a range of 5 to 30 mol% with respect to all diamine components in the polymer component. The compound of the general formula (II) has a strengthening effect on mechanical properties and heat resistance, and the present inventors have already filed patent application No. 2877609 in 1988.
Filed as an issue. The ratio of the aromatic diamine compound represented by the general formula (II) to all diamine components in the polymer component is less than 5 mol%, that is, [l: (m + n)]
Is less than 5, the effect of improving the heat resistance by the copolymerization of the compound of the general formula (II) is insufficient and sufficient heat resistance cannot be obtained.
If it exceeds 0 mol%, not only the melt viscosity of the resin becomes extremely high and molding becomes difficult, but also the molecular weight of the polymer is remarkably lowered, and the strength of the molded body is lowered.

Of all the diamine components in the polyamideimide resin polymer component of the general formula (I) according to the present invention, 4,4'-diamino except the aromatic diamine compound represented by the above general formula (II) is excluded. The ratio of diphenyl ether to m-phenylenediamine, that is, m: n is preferably in the range of 5: 5 to 9: 1. If it is out of this range, the melt viscosity of the polymer becomes high and it is difficult to mix graphite. Therefore, it is inconvenient.

The graphite used as a filler in the composition of the present invention may be either natural graphite or artificial graphite, and in the case of natural graphite, it may be scaly, scaly, or earth-like, but from the viewpoint of abrasion resistance. Is preferably scaly or scaly graphite, and has a particle size of 10 to 20 μm from the viewpoint of dispersibility in resin.
The following can be said to be preferable.

The thermoplastic resin composition of the present invention may be in the form of powder or pellets. In order to produce the thermoplastic resin composition of the present invention, the polyamide imide resin (A) of the general formula (I) contains 10 to 30% by weight of graphite (B) in the polymerization step of the polymer or the polymer polymerization. After mixing, various molded products can be directly obtained by a usual molding method such as extrusion molding, injection molding and compression molding. Further, the above mixture may be kneaded with a Banbury mixer, a Henschel mixer, a ribbon blender, an extruder, a roll or the like, and then pelletized to obtain a forming raw material. In order to make the dispersion uniform, the thermoplastic resin composition of the present invention is preferably manufactured by adjusting the conditions such as strength, temperature and time of mixing or kneading.

[0013]

EXAMPLES Hereinafter, the thermoplastic resin composition of the present invention will be described in detail with reference to examples, but the present invention is not limited to the following examples. [Examples 1 to 3] N in a polymerization vessel having a volume of 5 liters
-Methyl-2-pyrrolidone (4.5 liters) was added, and 50.48 g of N, N'-diphenyl-N, N'-1,4-phenylenebis (4-aminobenzamide) was added thereto.
4,4'-diaminodiphenyl ether 269.65
g and m-phenylenediamine (62.41 g) were added and melted. The solution was cooled to 0 ° C., 204.91 g of triethylamine and 426.44 g of trimellitic anhydride chloride were added, and the mixture was stirred for 2 hours. The viscous solution obtained is put into a mixer, and the volume ratio with water is 1: 1.
Was vigorously mixed to obtain a polymer precipitate. This precipitate was washed with water and then dried with a hot air dryer to obtain a polymer powder. The yield of the polymer was almost 100%, the weight average molecular weight by gel permeation chromatography was 33000, and the spectrum shown in FIG. 1 was obtained by infrared absorption analysis, which confirmed the presence of amide bond and imide group. As a result, it could be identified as a polyamide-imide resin represented by the following structural formula (III).

[Chemical 7] The polyamide-imide resin of structural formula (III) thus obtained and graphite (scaly graphite, average particle size 10.0 μm) were mixed at the ratio shown in Table 1, and a co-directional twin-screw extruder set to a cylinder temperature of 380 ° C. Were kneaded to prepare pellets.

Next, the pellets were molded into JIS 1/2 type dumbbell test pieces and 50 × 50 × 3 mm wear test pieces by an injection molding machine with a mold clamping pressure of 80 ton. The physical properties of the molded product were measured by a tensile test, a dynamic viscoelasticity test, and an abrasion test. The tensile test is conducted by a tensile tester (Autograph, Shimadzu Corporation) at a test temperature of 200 ° C. and a pulling speed of 5 mm.
It was performed under the condition of / min. The dynamic viscoelasticity test was performed using a dynamic viscoelasticity measuring device (RSA-II, manufactured by Rheometrics Co., Ltd.) under the conditions of a temperature rising rate of 10 ° C./min, a strain amount of 0.05%, and a frequency of 1 Hz. Wear test is JIS K7218
Test method 25 ℃, surface pressure 10kgf / c
It was carried out under the conditions of m ² , speed 100 m / min, no lubrication and two-cycle engine oil lubrication. The tensile strength was calculated from the tensile test, the glass transition temperature was calculated from the dynamic viscoelasticity test, and the abrasion amount was calculated from the abrasion test. The test results are also shown in Table 1.

[Comparative Examples 1 and 2] Examples 1 to 3 were carried out using the polyamide-imide resins used in Examples 1 to 3 alone and in the case where the graphite content was less than 10% by weight. The physical properties of the molded product were measured in the same manner as in. The test results are also shown in Table 1.

[0016]

[Table 1]

[Examples 4 to 6] The polyamideimide resins of Examples 1 to 3 and graphite were mixed at the ratios (weight ratios) shown in Table 2, and the melt flow test and kneading test of the mixtures were conducted. The melt flow test was conducted with a capillary rheometer (Rheograph, manufactured by Toyo Seiki Co., Ltd.) at a test temperature of 380 ° C. and L / D = 1.
/ (Mm), γ = 7 × 10 ² sec ⁻¹ . The kneading test was conducted using a twin-screw kneader (Laboplast Mill, manufactured by Toyo Seiki Co., Ltd.) at a test temperature of 380 ° C. and a sample volume of 60 c.
c, the rotation speed was 20 rpm. From the melt flow test, the melt viscosity was measured, and from the kneading test, the maximum kneading torque at the initial stage of kneading and the steady torque when the kneading torque became stable were measured.
The test results are also shown in Table 2.

[Comparative Examples 3 and 4] In the case where the polyamideimide resins of Examples 1 to 3 were used alone, and the compounding amount of graphite was less than 10% by weight, Example 4 was used.
-The same operation as in Example 6 was performed to measure the melting characteristics of the mixture. The test results are also shown in Table 2.

[0019]

[Table 2]

From the results shown in Tables 1 and 2, the polyamide-imide resin composition of the present invention has improved wear resistance due to the addition of graphite, and the heat resistance, moldability and mechanical strength which are the characteristics of the base resin. Since it also maintains, the mechanical strength, wear resistance, heat resistance, and moldability are all excellent.

[0021]

The thermoplastic resin composition of the present invention has excellent wear resistance, heat resistance and moldability and can be molded by various molding methods such as injection molding and compression molding. It is very suitable for use as a material such as a mechanical component having a complicated shape that is required to have good properties, such as a sliding component, and has a high utility value as an industrial material.

[Brief description of drawings]

FIG. 1 is an infrared absorption spectrum diagram of the polyamide-imide resins used in Examples 1 to 6 of the present invention.

Claims (1)

[Claims] 1. The following general formula (I): [However, in the general formula (I), l, m, and n each represent a molar ratio, and l: (m + n) is 5:95 to 30:70.
And m: n is in the range of 5: 5 to 9: 1], which is a random copolymer having a molecular weight of 10,000 to 300,000 and is a thermoplastic polyamide-imide resin 90.
A thermoplastic resin composition having a wear resistance of 70% by weight to 10% by weight of graphite.