JPS6337198A - Sliding member composition - Google Patents

Abstract

PURPOSE:To obtain a novel sliding member composition having improved self- lubricating properties and wear resistance, causing no sound in sliding, containing polyacetal, a specific polyethylene and an electrical conductivity imparter such as ketjenblack, etc., in a specific ratio. CONSTITUTION:(A) The aimed sliding member composition consisting of (A) 95-60wt% polyacetal, (B) 2-30wt% polyethylene having >=10 melt index and (C) 3-10wt% electrical conductivity imparter such as ketjenblack, etc. EFFECT:Has low friction and small variability in coefficient of friction.

Description

Detailed Description of the Invention (Al Industrial Field of Application) The present invention is applied to sliding materials such as relatively low-speed, light-load oil-free bearings and gears used in paper feeding sections of office machines, office electronic equipment, etc. Concerning the composition, it has low friction, low wear, and low fricative noise.
This was done in order to provide a conductive material with excellent sliding performance that does not cause so-called "squeal" and can prevent malfunctions due to accumulation of static electricity.

(bl Conventional Technology) Conventionally, conductive polyacecool resin has been used as a low-cost sliding member for relatively light-load bearings, gears, and other sliding members used in paper feeding parts of office machines, office electronic equipment, etc. Widely used.

However, although conventional conductive sliding materials have excellent self-lubricating properties and wear resistance, they have a slightly higher friction coefficient, and the friction coefficient fluctuates during sliding, resulting in stick-slip. This has the disadvantage of generating an unpleasant frictional sound, so-called "squeak," and it has been necessary to remedy this defect by applying a lubricant such as grease or oil to the sliding surface each time it occurs.

Furthermore, when gears made of conventional materials are combined, there is a drawback that wear increases rapidly.

Problems that the tc+ invention aims to solve As mentioned above, the currently widely used conductive sliding materials made of polyacecool suffer from high friction, fluctuations in the coefficient of friction, and high friction, which are considered to be the main causes of "squeal". Problems existed in terms of wear when the comrades were sliding.

The present inventors solved the drawbacks of conventional perturbation materials as described above, and pursued a high-performance sliding member composition with low friction and small fluctuations in the coefficient of friction, thereby preventing the occurrence of "squeal" and The present invention was completed through repeated research aimed at improving wear resistance.

(d) Means for Solving the Problems The inventors of the present invention first blended an appropriate amount of polyethylene with an MI (melt index) of 10 or more into polyacetal, so that the coefficient of friction changed over time with a 15% fineness compared to polyacetal. It was discovered that a sliding material that generates little "squeak" can be produced (Japanese Patent Application No. 61-098999), but the present invention can be achieved by further adding an appropriate amount of conductivity imparting agent such as Ketjen black or acetylene black to this material. It has been completed.

In this case, it is appropriate that the amount of polyethylene blended is 2 to 30% by weight based on the whole, and the blended amount of the conductivity imparting agent is 3 to 10% based on the whole.

This range has been established through experiments, and if the proportion of polyethylene exceeds 30%, the inherent rigidity and toughness of polyacecool will decrease and it will become easily deformed, reducing its practicality.

Furthermore, if the amount of polyethylene is less than 2%, the effect of reducing friction will be weak and it will not be sufficient to completely prevent "squeal".

Further, if the amount of the conductivity imparting agent is 3% or less, a volume resistivity of 10 to 10 parts cm, which is necessary for preventing static electricity, cannot be obtained.

The amount of conductive agent required to prevent static electricity is actually 3%.
The upper limit is not particularly restricted as long as it is above 10%, but if it exceeds 10%, kneading becomes somewhat difficult, and from the viewpoint of manufacturing, it is appropriate to set it at 10%.

(e) Effect The present invention reduces the It7' coefficient of friction and reduces fluctuations in the coefficient of friction by blending an appropriate amount of polyethylene of M110 or more with polyacetal and an appropriate amount of a conductivity imparting agent. , the "squeal" phenomenon during sliding does not occur, and the wear resistance is further improved.

(f) Examples Examples of the sliding member composition according to the present invention will be described below in comparison with a comparative example of a conventional sliding member, that is, a polyacecool conductive material.

Example 1 85 parts of polyacecool (product name: Duracon M90, manufactured by Polyplastics Co., Ltd.), 10 parts of polyethylene (product name: Petrocene 248, MI20, manufactured by Toyo Soda Co., Ltd.) and 5 parts of Ketjen Black (product name: manufactured by Lion Akzo Co., Ltd.) The mixture was mixed and kneaded using a single screw extruder, and then molded into a 10 x 200 x 6 t (1 piece) slope by injection molding. The volume resistivity of the material was 100 cm.

Example 2゜Example 1. Example 1 was prepared by blending 8 parts of acetylene black with the same polyacecool and polyethylene as in Example 1. A plate was formed in the same manner. The volume resistivity value of this material was 5-+5 100 cm.

Comparative example 1゜Example 1. The polyacecool used in Example 1 was used alone.
A plate was formed in the same manner. The volume resistivity of this material was 10 parts cm or more.

Comparative Example 2 A plate was molded in the same manner as in Example 1 using conductive polyacecool (trade name: Duracon ES5, manufactured by Polyplastics Co., Ltd.). The volume resistivity value of this material was 10Ω■.

A test piece (pin) of φ8×5 (n+) was machined from each of the above test plates, and a bottle-disk type friction,
The results of measuring sliding performance using an abrasion tester are shown in Figure 1 (changes in friction coefficient over time), Figure 2 (friction progression curve), and Figure 1.
The results are as shown in the table (presence or absence of "squeal" phenomenon, magnitude, and variation in friction coefficient).

The test conditions at this time were as follows.

Speed 0.39m/S Contact pressure 3 kg/cd Mating shaft 5US303 stainless steel mating surface roughness
Ra=0.12μm Lubrication Non-lubrication (dry) Table 1 Example 3゜Example 1. Comparative example 1.゛Material of Comparative Example 2 φ100x6
A disk of T was formed into a disk, and the sliding performance was examined by combining it with a bottle made of the same material.

The results are as shown in Table 2 for the noise during sliding, Figure 3 for the noise level at each frequency, and Figure 4 for the wear progression curve.

The test conditions were the same as in the other Examples and Comparative Examples, except that the mating disk was made of plastic and the contact surface pressure was 0.82 kg/crl.

As shown in the above test results in Table 2, the composition of the present invention not only has a lower coefficient of friction and is more stable than conventional polyacetyls and conductive polyacetals, but also exhibits less wear and noise when sliding. ” were also absent.

(g) Effects of the Invention As mentioned above, the sliding member composition according to the present invention is a conventionally widely used conductive polyacecool. It is a new sliding material that is extremely superior in that it has much improved self-lubricating properties and wear resistance, and does not generate the "squeak" during sliding that conventional materials could not overcome.

[Brief explanation of the drawing]

FIG. 1 is a graph showing changes over time in the coefficient of friction of each example and comparative example. Similarly, FIG. 2 is a graph showing a wear progression curve. FIG. 3 is a graph showing the noise level at each frequency when similar materials are slid together. FIG. 4 is a graph showing a wear progression curve when similar materials are slid together. Patent applicant Starlight Industries Co., Ltd. Figure 1 2. ) Su2 3 Haji uJ1 4 Yu Kan J2 Figure 2 Makoto 2 Tsutomu (km) Procedure Ne City Official Book (Spontaneous) August 1986 w Day 2, Title of Invention Sliding Member Composition 3, Relationship with the case of the person making the amendment Patent applicant address: 1-1-71 Tokuan, Tsurumi-ku, Osaka-shi Detailed description of the invention column - Azusa J'. " and insert "Thermoplastic resins such as polyacecool and polyamide are widely used as low-cost sliding members, but conductive versions of these materials are used when necessary." (2) On page 2, No. 12, the phrase "so-called fricatives" is corrected to "fricatives, so-called." (3) In the 12th line and the 18th line of page 2, correct the words "comrades" by one character each to "comrades". (4) In the 10th line of page 4, delete "Wake," and insert "It is possible to make the conductivity even thicker by increasing the amount of compounded amount."

Claims (1)

[Claims] By weight, (a) polyacetal 95-60%, (b)
Polyethylene 2 with an MI (melt index) of 10 or more
(c) a sliding part agent composition comprising 3 to 10% of a conductivity imparting agent such as Ketjen black or acetylene black.