JPS6051749A - Resin material having good electrical conductivity and friction characteristics - Google Patents

Abstract

PURPOSE:To provide the titled material having excellent electrical conductivity and friction characteristics useful for a video cassette reel, rotating sheet feeding parts of a copier, etc., by incorporating carbon black, graphite, and lubricating oil into a thermoplastic resin. CONSTITUTION:The titled material is prepared by incorporating carbon black, graphite, and lubricating oil into a thermoplastic resin (an acetal copolymer is especially preferable). The coexistence of the graphite and the carbon black can give remarkable conductivity with the addition of each in only a small amount to the resin. Excellent lubricating performance is also obtained owing to the improvement in friction characteristics by the graphite and in lubricity by the lubricating oil. Thus a resin material having both good conductivity and good friction characteristics is obtained. Moreover, a bearing material which produces conductive bearings and is applicable to a bearing system wherein no static charge builds up on a shaft can be made.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a conductive sliding resin material. VTR cassette reel,
The present invention relates to a resin material imparted with sliding properties and electrical conductivity, which can be applied to paper feed rotating members of copying machines, parts of other office machines or electronic equipment, etc.

Conventional technology The demand for VTRs has been increasing rapidly in recent years, but since cassette reels tend to generate static electricity due to friction and peeling when the tape is running, antistatic resin is used in the cassette reel, so that the charge on the cassette reel does not affect the image. Preventing such adverse effects has greatly contributed to the improvement of the quality of VTRs and their widespread use. The reel stand of the VTR is still integrated with the gooley and is driven by a belt, but the friction between the belt and the reel causes the reel stand to become charged, and the charge is discharged from the reel stand to the IC, causing the VTR to malfunction. The problem is also being solved by antistatic resins.

In addition, glass bearings have recently been used as bearings to support the paper feed rollers in electrostatic copying machines, etc., but they are prone to static electricity that builds up on the paper, uneven copying, and incorrect paper feed due to adhesion between the shaft and the paper. There is a problem with the discharge die from the shaft. Providing a peeling mechanism for peeling off paper adhered to a sheet roller provided with an antistatic mechanism would complicate the mechanism, potentially lowering the reliability of the copying machine, and increasing weight and cost.

Polymer materials such as plastic usually have a resistance of 1014Ω・α
It has a volume resistivity of more than 100%, and is easily charged due to friction, etc. Due to this excessive charge, polymer materials may attract dust or receive electric shock.
As a countermeasure to this problem, materials in which antistatic agents are mixed into plastic are supplied as needed.

Materials such as the VTR reel stand mentioned above cannot be satisfied with simply preventing static electricity; they are also required to have conductivity with low resistance, and actively dissipating the charge to the ground is required to further improve image quality. Sleeping.

Additionally, in the United States, there are regulations on radio wave containment in order to eliminate radio wave interference in electronic devices such as microcomputers and VTRs, and for this purpose, it is necessary to impart conductivity to the Norastisox material used in the housings of electronic devices. ing. Methods for imparting conductivity to plastic include (1) addition of conductive carbine, (2) addition of metal powder or fiber, (3) addition of carbine fiber, or (4) metallization of the surface of the molded product. It is being said. Metallizing (4) can be applied to housings such as electronic devices or ICs, but it can also be applied to members that involve movement such as rotation or sliding. (2
) and (3), when the addition of metal powder/fibers or carbon fibers is applied to a sliding member, for example, there is a problem of damaging the mating material. Furthermore, for example, when carbon fiber-added plastics are used as sliding members, there is a drawback that the coefficient of friction increases with time of use. (1)
The addition of conductive carbine is a method of adding carbon black (amorphous carbon), which has the lowest specific volume resistivity among carbon materials, to a 7°-7 stick. From this method 1, by adding 8 to 15M carbon black to the polyacetal resin, 102 to 103 Ω.
A conductive resin material having an intrinsic lft resistance on the order of magnitude can be obtained. However, although this conductive resin material has conductivity, its sliding properties are inferior to those without carbine black added. In particular, the conductive resin material described above is unsuitable for use as a bearing.

As described above, proposals have been made to impart electrical conductivity to resin materials, but sliding properties have not been taken into consideration.

OBJECTS OF THE INVENTION Therefore, it is an object of the present invention to provide a resin material that has both electrical conductivity and sliding properties. Furthermore, the present invention provides a novel bearing material that can be applied to a bearing device that imparts electrical conductivity to the bearing and does not charge the shaft.

Structure of the Invention The above-mentioned object of the present invention is to provide a conductive sliding material, which is made of a thermoplastic resin mixed with carbine blank, graphite, and lubricating oil, and has electrical conductivity and excellent sliding properties. The structure of the material that provides the dynamic resin material (simply referred to as a sliding material in the following section) will be explained.

In the sliding material of the present invention, the resin material serving as the base material may be any thermoplastic material, among which polyphenylene oxide, 7j? Liftylene 7-talate, polyamide (eg, Nylon, trade name), polycarbinate, and Delia Shichinohelu are preferred, and polyacetal is particularly preferred. Of the copolymer type and homopolymer type polyacetal, the former is preferred.

Graphite, which is a component of the sliding material of the present invention, is a component that particularly improves the electrical conductivity and improves the sliding characteristics by increasing the lubricating characteristics. Carbin black, which will be described later and is one of the components of the sliding material of the present invention, deteriorates the sliding properties compared to those without addition of carzene, but graphite compensates for the deterioration in sliding properties caused by carbon black, and furthermore, without the addition of carbon. Achieves better sliding characteristics than those of

In addition, graphite has a specific volume resistivity of 10% compared to resin materials.
Although the graphite is more than twice as low, it is difficult to impart conductivity to the resin by adding it alone, and a large amount of graphite, 40% (weight percentage) or more, is required to impart conductivity to the resin. It is.

However, in the sliding material of the present invention in which graphite coexists with carbine black, kerf J? Even if black or graphite is added in a small amount, it imparts significant electrical conductivity.

The upper limit of the amount of graphite added may be the same as the upper limit of the amount of graphite that can be kneaded with the resin material, and the maximum amount of graphite added is approximately 40 inches.

However, if the amount of graphite is too large, the strength of the sliding material will be reduced and the sliding properties will also be inadequate. Therefore, when trying to provide a sliding material with particularly good sliding properties, the upper limit of the amount of graphite added is 25%. % is preferred. In terms of sliding properties, graphite is preferably 5 or more thick. When graphite is used to retain lubricating oil as described below, the amount of graphite added is preferably O-25%. In the sliding material of the present invention, the amount of graphite added is generally 3
-30%, about 20% is most preferred.

As the graphite, naturally occurring raw graphite and scaly graphite are used, as well as artificial graphite obtained by heating and crystallizing amorphous carbon obtained from coal, oil, coke, etc. However, artificial graphite has approximately 10 times the friction property measured by wear amount (wear tl/10 times) than natural graphite.
Improve. There is no particular restriction on the particle size of the graphite used in the sliding material of the present invention, but it is preferably 50 μm or less.

Carbon black, which is one component of the sliding material of the present invention, is a component that imparts electrical conductivity. The upper limit of the amount of carbon black added coincides with the upper limit of the amount added to the resin by kneading. However, it is preferable to select the following range depending on particularly desired characteristics. That is, if high electrical conductivity is particularly desired as a characteristic of the sliding material of the present invention, the addition amount of carbon black is preferably d7 to 30%, and if good sliding properties are desired, id:3 to 10% is preferred. If you want something with good both properties, 7-10% is good. There are no particular restrictions on the type of carbine black, but acetylene black (acetylene carbonized into an amorphous form) is preferred, and ultrafine carbon black below IOA (for example, carbon black for special furnace Quizo) is preferred. Particularly preferred are those commercially available under the trade name Black.

The lubricating oil, which is one component of the sliding material of the present invention, is a component that imparts opening performance. In the sliding material of the present invention, excellent lubrication performance can be obtained due to the improvement in sliding performance due to graphite and the improvement in lubrication performance due to lubricating oil. Such lubricating oil may be contained in the lubricant material, contained (oil-impregnated) in graphite and/or carbine black, or both may be contained simultaneously. Lubricating oil generally tends to lower electrical conductivity, but when lubricating oil is included in the resin material, the sliding material has high electrical conductivity due to the pure graphite that is not impregnated with oil. on the other hand,
The electrical conductivity of sliding materials containing graphite is relatively low.

It is preferable that the type of lubricating oil has heat resistance up to 250℃.
Yes, there are no particular restrictions.・Jet engine oil is particularly preferred, but general engine oil (heat resistance of about 180°C) may also be used. The amount of lubricating oil added is preferably less than 10 inches, particularly preferably 1.5 to 3 inches.

Fluorine, which is an optional component of the sliding material of the present invention, is a component that has the effect of further improving the sliding properties. For this effect, it is preferable that the fluororesin particles have a diameter of 25 μm or more.

When the particle size is 7 to 8 μm, the effect of improving sliding properties is exhibited, but when the volume resistivity is about 1030·α, a certain degree of excellent electrical conductivity can be obtained. The amount of fluororesin added is generally 5% or less, or the particle size of the fluororesin is 25μm to 4μm.
If it is 0 μm, even a larger addition amount, for example, 6 inches, can be used. Fluororesin has excellent heat resistance among resins, but its wear resistance is poor. However, the fluororesin used as a component of the sliding material of the present invention is effective in preventing uneven wear (unilateral wear) of the sliding material. In other words, even if the sliding material is slid in a situation where it is in partial contact with the mating material, it has the effect of preventing uneven wear from progressing.

The role of the components in the sliding material of the present invention will be further explained with reference to FIGS. 1 to 7 showing experimental examples. In these drawings, Gr is graphite, CB is carbon black, and PTFE is polytetraful. In Figure 1, 20% or 5 tigraphite, 2 thi lubricating oil, 4 thi polytetrafluoroethylene, and carbon black (addition amount shown on the horizontal axis). ,
The coefficient of friction of the sliding material whose remainder is polyacetal resin (
It is a graph showing (b). As shown in Figure 1, carbon black tends to increase the coefficient of friction, but this tendency is alleviated by graphite.

Figure 2 shows 6 inches, 10% carzen black 2 inches ff4M
It is a graph showing the coefficient of friction (μ) of a sliding material consisting of t44% polytetrafluoroethylene (added amount shown on the horizontal axis of graphite) and the balance polyacetal resin. Second
It can be seen from the figure that graphite lowers the coefficient of friction, and the degree of this decrease is greater when the amount of kerf 1-'noblack added is small.

The third @ is carbon black (addition amount shown on the horizontal axis), 2
It is a graph showing the friction coefficient (lj) of a sliding material consisting of 0% graphite, 22% lubricating oil, 0.4 or 8% polytetrafluoroethylene, and the balance polyacetal. From this graph, it can be seen that polytetrafluoroethylene tends to lower the coefficient of friction.

FIG. 4 is a graph showing the coefficient of friction (14) of a sliding material consisting of 6-thickened black, 20-thick graphite, 2-thick lubricating oil, polytetrafluoroethylene (addition amount shown on the horizontal axis), and the balance polyacetal. From Figure 4, PTF
It can be seen that as the amount of E added increases from 0 to 10 inches, the friction coefficient (μ) decreases, and beyond that, the friction coefficient remains almost constant.

FIG. 5 shows a 6-cycle carbon black, (a) a 2-channel lubricating oil with the amount of addition shown on the horizontal axis, or (b) a 4fI polytetrafluoroethylene with the amount of addition shown on the horizontal axis; It is a graph showing the volume resistivity (p) of a sliding material other than polyacetal. From this graph, it can be seen that polytetrafluoroethylene and lubricating oil significantly reduce the electrical conductivity when the temperature is 4 or more. In addition,
It is thought that polytetrafluoroethylene is interposed between carbon black particles and blocks the current path.

Figure 6 is a graph showing the specific volume resistivity (ρ) of a sliding material consisting of 20% graphite, 2% lubricating oil, 4% polytetrafluoroethylene, carbon black (amount shown on the horizontal axis), and the remainder polyacetal. It is. The specific volume resistivity was determined in accordance with JIS K6911 resin resistivity measurement method.

It is a graph showing the load capacity of a sliding material consisting of litertrafluoroethylene and the remainder polyacetal.

The load capacity test was conducted under the following conditions.

(a) Testing machine Ni-last type friction and wear tester (b) Sliding speed: 0.2 m / 5eeC Load: 5 kcg
/ hr stepwise increase (→ mating material: SUJ -2 (
Quenching) (e) Lubrication: Dry conditions (e) Load application method Ni thrust load As shown in Figure 7, carbon black tends to reduce the load capacity, but it can be seen that this tendency is alleviated by graphite. Note that when the load capacity decreases, the sliding material will break under low load due to the load received from the mating material.
Alternatively, even if it does not lead to destruction, fatigue is likely to occur, resulting in poor sliding characteristics.

The representative characteristics of the sliding material of the present invention are volume resistivity (p)=1
020・m, friction coefficient (μ) = 0.5 (μ = 0.4 months?
Minao, which contains litertrafluoroethylene (Yang@),
In conventional materials containing only carbon black, volume resistivity ω) -103 to 104 Ω・α, friction coefficient (I4≠
07 or higher, it can be seen that the properties of the sliding material of the present invention are revolutionary.

The method for manufacturing the sliding material according to the present invention will be explained below.

After weighing and mixing the predetermined ingredients whose particle size has been adjusted, and adding coupling agents and viscosity modifiers as necessary, extrusion into a kneader and pelletization, followed by shaping into a predetermined shape with a molding machine. Shape. When graphite or carbon black is impregnated (oil-impregnated) with lubricating oil, graphite q is stirred in the lubricating oil and then kneaded to easily form soy sauce τ gate fat.

Example Examples of the present invention will be described below in Table 1.

In Table 1, POM is Koirimartaizo's polyacecool, CB is carbon black (trade name Touchen Black), Gr (L equivalent to Tokai Carpin Co., Ltd. standard G117)
0IL (Gr) is jet engine oil (partially impregnated with graphite), 4F is polytetrafluoroethylene, and the numbers indicate percentages of the total. These POMs were kneaded, made into pellets, and molded to prepare specimens, which were then subjected to measurement. "Conductivity" is 5-a-
The figure shows the calculation 'volume resistivity ω) in units of n-pieces.

"Abrasion" is 2.0 for the first 10 minutes after sliding distance of 10 km.
After 5 kg%, load is 10 kg (constant), sliding speed O0'2rrv/8ec, mating material SUJ 2 (quenched)
, shows the amount of wear (in da) mixed under the conditions of dry lubrication and thrust type friction and wear tester.

"μ" indicates the friction coefficient, and "load" indicates the load capacity (unit: kg) measured under the above-mentioned load conditions.

Note that similar characteristics were obtained when polyamide 1° was used instead of POM.

Effect (a) Since the sliding material of the present invention not only has an antistatic function but also has conductive properties, it can be used as an electrical component that is energized or grounded, and it can prevent harmful effects caused by charging, such as image after-sound in VTRs or copying devices. can thoroughly prevent paper adhesion. It is also possible to use it as an IC package and set the JCz9 package to ground potential.

(b) The frictional properties of the sliding material of the present invention are extremely strong over a long period of time.
The stability improves the reliability of electrical parts that rotate or slide.

Since the sliding material of the present invention has excellent wear resistance,
If this is used for electrical parts that rotate and slide, it is expected that there will be less wear and tear on the parts and that maintenance will be easier.

B) By utilizing the property of excellent load capacity and the effect of (a) above, the sliding material of the present invention can be used in small and lightweight bearing devices that require electricity.

09 Since the sliding material of the present invention does not damage the mating blade, a soft and lightweight resin material can be used as the mating material, and a lightweight IWh receiving device in which the resin material products slide together can be manufactured.

(f) Since the sliding material of the present invention has a high load capacity under a slanut load, it can also be used as a current-carrying type thrust bearing.

[Brief explanation of the drawing]

Figure 1 shows 20% or 5% graph eye 1-12% moisture? J
It is a graph showing the coefficient of friction (ll) of a sliding material made of t-oil, 4-polytetrafluoroegulene, carbon black (addition amount shown on the horizontal axis), and the balance being polyacetal resin. Figure 2 shows 6%, 10% carbine black, 2% lubricating oil, 4% polytetrafluoroethylene, and graphite (
(addition amount shown on the horizontal axis), and the friction thread count (μ) of a sliding material made of a polyacetal resin with the remainder being a graph. Figure 3 shows carpin black (addition amount shown on the horizontal axis), 2
0t graphite, 2.2t lubricant, O4 or 8t? This is the coefficient of friction (G2 showing the slope) of the sliding material made of litertrafluoroethylene and the remainder polyacetal. FIG. 4 shows the coefficient of friction of a sliding material consisting of 6 to 10 black, 20 to graphite, 2 to 2 lubricating oil, polytetrafluoroethylene (the amount added is shown on the horizontal axis), and the balance being polyacetal. Figure 5 shows the addition amount of polytetrafluoroethylene shown on the horizontal axis for 6-tank black, (II) 2-ch lubricating oil, or (b) 4%, #litertranfluoroethylene on the horizontal axis. It is a graph showing the amount of lubricating oil added, the remainder - rear secure, and the volume resistivity of a different sliding material. Figure 6 is a graph showing the volume resistivity (, p) of a sliding material consisting of 20 Tigra 7ite, 2 Ti lubricating oil, 4 polyketrafluoroethylene, carbon black (amount shown on the horizontal axis), and the remainder polyacecool. It is. Figure 7 shows carbine black (addition amount shown on the horizontal axis), 2
0% graphite, 2% lubricating oil, 4 polytetrafluoroethylene5. It is a graph showing the load capacity of a sliding material consisting of the remainder polyacetal. % Applicant Taitoyo Kogyo Co., Ltd. Patent agent Akira Aoki Patent attorney Kazuyuki Nishidate Patent attorney Takashi Murai j...− Patent attorney Akira Yamaguchi Patent attorney Masaya Nishiyama Figure 2 Figure 4 + J+ PTFE '/, O! L'10 Figure 6 CB Hill: ('/,) Continuation of page 1

Claims (1)

[Claims] 1. An electrically conductive sliding resin material characterized by not containing carbon black, graphite, and lubricating oil in a thermoplastic resin, and having electrical conductivity and excellent sliding properties.