JP2008274148A - Resin sliding members and sliding parts / sliding devices - Google Patents

Abstract

A resin-based slide that provides a sliding surface that is compact, lightweight, non-lubricated, and can be used for a long period of time, with characteristics such as maintaining and sustaining high lubrication and significantly reducing the aggressiveness of the mating material. Provided is a sliding member / sliding device including a moving member and a sliding surface thereof.
A resin-based sliding member is a composite based on a self-lubricating thermoplastic olefin resin, and at least becomes Rockwell hardness (conforming to R scale of JISK7171) / bending elasticity The ratio of the numerical value of the ratio (conforming to JISK7171) is in the range of 25 to 45, and is composed of a composite that gives a sliding surface whose dynamic friction coefficient is lower than that of the base material resin.
[Selection figure] None

Description

The present invention relates to a resin-based sliding member that maintains and sustains high lubrication and gives the sliding surface a characteristic that the aggressiveness to the counterpart material disappears or decreases, and a sliding portion and a sliding device including the sliding surface. .
Specifically, the present invention has high lubricity sustainability (especially long-term sustainability of high lubrication) on the sliding surface of a sliding device that is required to be compact, lightweight, oil-free, long-term use, etc. The present invention relates to a resin-based sliding member that imparts a significant decrease in aggressiveness and the like, and a sliding portion / sliding device including the sliding surface thereof.

Fluorine-based, which is excellent in self-lubricating and mechanical strength, for resin-based sliding members that constitute sliding devices used in small-sized, lightweight, oil-free, such as copiers, printers, and facsimile machines Resin (for example, polytetrafluoroethylene resin, polytetrafluoroethylene-chlorotrifluoroethylene resin, tetrafluoroethylene-hexafluoropropylene copolymer resin, etc.) is used as a raw material resin (see, for example, Patent Document 1) ).
Resin-based sliding members made of resins other than fluorine-based resins have insufficient self-lubricating properties derived from the resin, and therefore are highly self-lubricating fluorine-based resins (typically fluorine-based resins such as polytetrafluoroethylene resin). ) And particularly a solid lubricant (typically molybdenum disulfide, graphite, boron nitride, etc.) having an inorganic layered structure having a large self-lubricating property. (See Patent Document 2).

In resin-based sliding members other than fluorine-based resins, in order to obtain practical high lubricity, it is common to add 20% by volume or more of a solid lubricant having an inorganic layered structure.
However, in a sliding device using a resin-based sliding member that is often used in a lightweight and oil-free manner, if an inorganic solid lubricant is present on the sliding surface, the mating member (especially a soft metal such as aluminum) is in operation. And the resin) are attacked to increase the friction coefficient or destabilize the sliding surface.

Patent Document 1 3618199 Patent Document 2 3316164

The conventional resin sliding members have the following problems (1) to (5).
(1) The wear of the sliding surface is remarkable and the life of the sliding surface is short.
(2) The basic conditions of the sliding surface such as friction coefficient and wear resistance are insufficient.
(3) A sliding surface containing a solid lubricant having an inorganic layered structure will increase wear and attack the mating member.
(4) When the hardness of the resin-based sliding member is lowered, the opponent attack is reduced, but the friction coefficient is increased and the function of the sliding surface is lowered.
(5) No effective means has been proposed for solving both high lubrication sustainability and a decrease in the aggressiveness against the mating member.
From the data of many experiments related to composites based on self-lubricating thermoplastic olefin-based resins, the physical properties of composites can be determined from the correlation between hardness, elasticity, and coefficient of friction. The present inventors have found that a sliding surface having technical characteristics such as high lubrication sustainability and reduced attacking property against a mating member can be specified.

The first aspect of the present invention achieves the following objects.
(A) To provide a resin-based sliding member that imparts to a sliding surface (especially a sliding surface that is slid under oil lubrication) a characteristic in which high lubrication durability and aggressiveness against a counterpart member have disappeared or decreased. Objective.
(B) Provided is a resin-based sliding member that provides a sliding surface (especially a sliding surface that is slid under oil lubrication) having both sliding characteristics with low friction and excellent wear resistance and excellent mechanical characteristics. This is also the purpose.
(C) To provide a resin-based sliding member that provides a sliding surface (especially a sliding surface that slides under oil lubrication) that has sliding performance accurately, stably and safely even after long-term use; Also aimed at.
(D) It is also an object of the present invention to provide a resin-based sliding member that can be easily reduced in weight, promoted recycling, and reduced manufacturing costs during industrial implementation.

The second aspect of the present invention achieves the following objects.
(A) A slide having a sliding surface (particularly a sliding surface that is slid under oil lubrication) that is lightweight, unaffected by configuration, maintains high lubricity, and has reduced aggressiveness against the mating member. An object is to provide an apparatus.
(B) Sliding surfaces with excellent sliding characteristics (that is, low friction and wear resistance), reduced attacking properties against mating members, and excellent mechanical characteristics (especially sliding under oil lubrication) Another object of the present invention is to provide a sliding device having a sliding surface.
(C) Another object of the present invention is to provide a sliding device having a sliding surface that slides accurately, stably and safely even when used for a long time (especially a sliding surface that slides under oil lubrication). To do.
(D) Another object of the present invention is to provide a resin-based sliding device that can be easily reduced in weight, promoted recycling, and reduced manufacturing costs during industrial implementation.

The resin-based sliding member according to the first invention (the invention according to claim 1) is a composite having a self-lubricating thermoplastic olefin resin as a base material, and has at least Rockwell hardness ( JISK7171 R scale) / flexural modulus (conforming to JISK7171) numerical ratio is 25-45, and is characterized by comprising a composite that provides a sliding surface with a lower coefficient of friction than the base material. To do.
The sliding part / sliding device according to the second aspect of the present invention (the present invention according to claim 3) is a resin system in which the base material of the self-lubricating thermoplastic olefin resin accounts for 75% by weight or more by injection molding. The sliding member is changed to a sliding part / sliding device, and the resin-based sliding member has a numerical ratio of at least Rockwell hardness (conforming to R scale of JISK7171) / bending elastic modulus (conforming to JISK7171). It is 25-45, Comprising: It consists of the composite_body | complex which gives the sliding type sliding surface whose friction coefficient is lower than a base material, It is characterized by the above-mentioned.

According to the resin sliding member of the first aspect of the present invention, various effects represented by the following (1) to (5) can be obtained.
(1) The sliding surface (especially the sliding surface that is slid under oil lubrication) maintains high lubricity and reduces the attacking property against the mating member.
(2) The frictional change over time of the sliding surface (especially the sliding surface slid under oil lubrication) is slight and there is no increase in wear over time.
(3) Sliding surfaces (especially sliding surfaces that are slid under oil lubrication) have both excellent sliding properties and mechanical properties.
(4) The sliding surface (especially the sliding surface that is slid under oil lubrication) keeps sliding accurately, stably and safely for a long time.
(5) It is easy to lighten, recycle, reduce manufacturing costs, and form a sliding part / sliding device with a sliding surface.

According to the second aspect of the present invention, various effects represented by the following (a) to (d) can be obtained.
(A) A sliding portion having a sliding surface that is lightweight, maintains high lubrication without being restricted in form, and has reduced aggression against a mating member (particularly, a sliding surface that slides under oil lubrication). -A sliding device is obtained.
(B) A sliding part / sliding device having a sliding surface having both excellent sliding characteristics (that is, low friction / wear resistance) and excellent mechanical characteristics can be obtained.
(C) A sliding part / sliding device having a sliding surface that slides accurately, stably and safely even when used for a long time can be obtained.
(D) In industrial implementation, it is possible to obtain a sliding portion / sliding device that can be easily reduced in weight, promoted recycling, and reduced manufacturing costs.

The resin-based sliding member and sliding device of the present invention will be specifically described below based on the best embodiment.
<Resin-based sliding member of the present invention>:

The resin-based sliding member according to the present invention (hereinafter sometimes abbreviated as a sliding member) is made of a composite having a self-lubricating thermoplastic olefin resin as a base material (occupying most of the quantity). It is a material constituting a resin-based sliding portion / sliding device.
The sliding member (composite) has a Rockwell hardness (conforming to JISK7171 R scale) and flexural modulus (conforming to JISK7171) GPa ratio (that is, Rockwell hardness / bending elastic modulus) of 25 to 25. In the range of 45, a sliding surface having a lower friction coefficient than that of the base material is provided, so that the effect of the present invention can be enjoyed.
In the present invention, high lubrication durability on sliding surfaces (especially sliding surfaces that are slid under oil lubrication), loss or decrease in aggressiveness against the mating member, accuracy and stability over long periods of sliding. It has been experimentally proved that sliding performance such as safety and safety can be grasped and specified by comparing their numerical range and the coefficient of friction with the base material (Examples and Comparative Examples in this specification) (See Table 1 and Table 2)
The Rockwell hardness / bending elastic modulus ratio is simply obtained by dividing the Rockwell hardness (conforming to JISK7171 R scale) value by the bending elastic modulus (conforming to JISK7171 R scale) GPa value. (Hereinafter, sometimes referred to as “ratio of rigidity / elastic modulus”). For example, in Example 1 of Table 1, the Rockwell hardness (conforming to R scale of JISK7171) is 58 and the flexural modulus (conforming to JISK7171) is 1.6 GPa, so the rigidity / elastic modulus ratio is simple In addition, 58 / 1.6 = 36.

Examples 1 and 2 and Comparative Examples 1 to 3 are composites of the same base material, and test specimens having slightly different mechanical properties (typically hardness, bending elasticity, etc.), friction performance, and wear performance. In
It is a part of typical example of the experiment which investigated establishment of the correlation with the physical property of a test piece, and the objective and effect of this invention.
As a result, if the rigidity / elastic modulus ratio is in the range of 25 to 45 and the condition that the coefficient of friction is lower than that of the base material (especially 10% or more lower), the sliding surface having the effect of the present invention (especially It has been found that a resin-based sliding member that provides a sliding surface that slides under oil lubrication can be obtained.
If the rigidity / elastic modulus ratio is less than 25, the strength is insufficient when a small precision sliding part / sliding device is used. When the ratio of rigidity / elastic modulus is greater than 45, the attacking property against the counterpart material is increased during sliding. Moreover, the lower limit of the friction coefficient of the resin-based sliding member is, for example, about 30% of the friction coefficient of the base material. This is because, in order to further reduce the coefficient of friction, negative factors such as the need to add an amount that causes the inorganic solid lubricant to attack the counterpart material become large.

The “friction coefficient” of the present invention is a dynamic friction coefficient (also referred to as a dynamic friction coefficient) that represents a motion resistance that appears on a contact surface when an object moves in contact with another object. The dynamic friction coefficient is expressed by a numerical value called μ (mu).
The dynamic friction coefficient measuring device has the same basic structure (see ASTM F609-96)
The test piece of the sliding member to be measured and the mating material are brought into contact with each other under a constant load, and one of them is moved (mostly rotational movement), and the frictional resistance generated at that time is transmitted to the controller and displayed. It has become.
FIG. 1 is a schematic view of an apparatus for measuring the dynamic friction coefficient of Examples and Comparative Examples, and the basic configuration is the same as that of a general dynamic friction coefficient measuring apparatus. In FIG. 1, the sliding member to be measured is a bush-shaped test piece and one end face contacts with a mating material disk (not shown) with a constant load, the mating material disk is fixed to the housing, and the housing rotates. The test piece and the mating material disk are brought into contact with each other under a constant load.
The frictional resistance generated at that time is recorded on a recorder through a load cell.
In addition, when the requirement of the friction coefficient of the resin-based sliding member of the present invention is expressed by a dynamic friction coefficient, it is 0.20 μm or less.

<Self-lubricating thermoplastic olefin resin>:
Resins that provide the corresponding mechanical strength (for example, resins with a medium or higher density, high molecular weight, etc.) can be used as materials that make up sliding parts and sliding devices with small and complex shapes. In addition, it is necessary to have a melt flow rate (conforming to JISK7212) capable of injection molding. Further, since the thermoplastic olefin resin occupies 75% by volume (preferably 90% by volume or more) of the sliding member, it is necessary that the thermoplastic olefin resin itself has self-lubricating properties.
As the self-lubricating thermoplastic olefin resin, for example, polyethylenes having a melt flow rate capable of injection molding (for example, medium density polyethylene, high density polyethylene, ultrahigh molecular weight polyethylene) and polypropylenes are suitable. They can be a single substance, a mixture, a copolymer, or a modified substance.
From the viewpoint of having self-lubricating properties, a high-density resin is suitable. As for polyethylene, industrially produced and sold polyethylene is separated into low density, medium density, and high density, so as a general-purpose product, it has high mechanical strength and molding processability. The use of excellent high density polyethylene is suitable.

If the melt flow rate of high-density polyethylene (which may be described as formability / moldability) is in the range of about 2 to 50 g / 10 minutes, the sliding portion (for example, a gear, a bearing) In the case of 15 g / 10 min or less (preferably 10 g / 10 min or less), the slide member having rigidity and impact resistance can be injection molded.
However, when the melt flow rate is 2 g / 10 min or less, injection molding into a precise shape such as a gear becomes difficult. Moreover, if the melt flow rate is 30 g / 10 min or more, injection molding is easy, but there is a tendency for impact resistance and wear resistance to decrease. In addition, a crystal nucleating agent (for example, a dibenzylidene sorbitol compound or the like) can be contained in this high-density polyethylene to make injection molding a high cycle. In the case of a self-lubricating thermoplastic olefin resin other than polyethylene, it is possible to select under the same conditions.

<Preparation of sliding member based on base material value>
The combination of the raw materials for the sliding member is selected based on the measured value of the stiffness / elastic modulus ratio of the test piece of the target base material resin (self-lubricating thermoplastic olefin resin) prepared by injection molding. The target base material resin has a base material amount of 75 volume% or more (preferably 90% or more) and occupies the sliding member so that the physical properties derived from the base resin are reflected on the sliding surface. The rigidity reduction material is blended with the resin so that the rigidity / elastic modulus ratio of the target base resin is less than 45. It is desired that the material for lowering the rigidity of the base resin has compatibility with the base resin and is effective in reducing the hardness of the base resin with a small amount of blending. When the blending amount of the material for reducing rigidity is increased, other physical properties (for example, friction coefficient) and the mechanical strength of the sliding member are affected.
Examples of the thermoplastic elastomer that is a material for reducing rigidity include olefin elastomers, polyamide elastomers, polyester elastomers, and silicone elastomers.

Also, a lubricity enhancing material (lubricity improving material) is blended to make the sliding surface (especially the sliding surface that slides under oil lubrication) given by the sliding member have a lower coefficient of friction than the base resin. Thus, the sliding surface is made highly lubricous (that is, a low coefficient of friction). As the lubricity enhancing material, a material having a large self-lubricating property (generally, a material having a self-lubricating property larger than that of the base resin) is blended in an amount that does not generate an aggressiveness to the mating member.
Lubricity enhancing materials include, for example, fluorine-based resins (for example, polytetrafluoroethylene resin), inorganic layered solid lubricants (for example, graphite, molybdenum disulfide), self-lubricating inorganic compound powders (for example, , Stearic acid compounds, etc.), organic compounds (eg, montanic acid esters, etc.), mineral powders, oily compounds (eg, silicone oil, mineral oil, etc.), and the like. In general, a lubricity enhancing material having a higher self-lubricating property than the target base material resin is blended in order to make the sliding member have a lower coefficient of friction than the base material resin. However, the sliding member (composite) has a coefficient of friction that is 10% or more lower than that of the base material resin (more preferably, a coefficient of friction that is 25% or lower than that of the base material resin). It is preferable from the point of making it.
When the lubricity enhancer is a solid lubricant having an inorganic layered structure, it is blended in an amount that does not cause an aggression to the mating member due to the sliding surface. The blending amount that causes attack on the mating member differs depending on the type of solid lubricant, the form of the powder, and the like, so the blending amount is determined according to the conditions of the solid lubricant. In general, if the amount of the solid lubricant having an inorganic layered structure is, for example, 10% by volume or less (based on the capacity of the sliding member (composite)), the sliding surface is attacked against the other member Does not impart sex.

When the sliding part constitutes a small, complicated and precise sliding part / sliding device, it is desirable from the point of use to increase the mechanical strength. In such a case, a reinforcing material is added. Reinforcement such as enhancement of mechanical strength of the sliding portion or enhancement of mechanical strength / slidability is performed.
The reinforcing material is, for example, an inorganic whisker (for example, calcium carbonate whisker), a reinforcing fiber (for example, glass fiber, carbon fiber, aramid fiber, etc.), a powdery filler (for example, talc, calcium carbonate, etc.), or the like. . The reinforcing material is used under the condition that the reinforcing effect on the sliding portion is increased (for example, in the case of calcium carbonate whisker, the aspect ratio is 3 to 50). In addition, the reinforcing material is also blended in a small amount that does not impart an aggressiveness to the mating member on the sliding surface of the sliding portion.

<Manufacture of sliding parts and sliding devices>
For the sliding material, self-lubricating thermoplastic olefin resin of the base material and other materials are kneaded and heat-melted by a kneading machine to form pellets and other shapes necessary for injection molding, and then injection molding and desired Molded into a shaped sliding part / sliding device. The means and apparatus for kneading and the method and apparatus for injection molding are not limited and can be arbitrary, and the same applies to the injection molding apparatus and the like.

<Sliding part and sliding device>
The sliding member of the present invention can be a material constituting a sliding part / sliding device of any form. Typical examples of the sliding part / sliding device include gears, bearings. And mechanical parts. The sliding part / sliding device itself may function independently, or may function as a part.
The gear can be various gears such as an involute spur gear, a helical gear, a worm gear, a worm wheel, and the like. The sliding member of the present invention is a low-hardness material and is considered particularly effective for noise reduction.
The bearing has the function of supporting the load and the function of sliding and rolling the parts that move relative to each other, for example, a rolling bearing, a single shaft bearing, a split bearing and a seal bearing are possible. This is an example in which the effects of the present invention can be maximized.
The mechanical components can be, for example, bushes, wire drums, door lock actuator gears, wire guards, and other mechanical components.
In general, the sliding portion / sliding device is used as a synonym. However, when the entire sliding device and a part of the sliding surface are formed from the sliding member of the present invention, the sliding portion is used as a limited term indicating only the sliding surface and its vicinity. Therefore, in the claims and the specification, the sliding portion and the sliding device are described as the object of the sliding portion.
In the present invention, it is in accordance with the object of the present invention, and any modification or partial change and addition is optional as long as the effects of the present invention are not particularly impaired. It is.
EXAMPLES Next, although this invention is demonstrated concretely based on an Example, an Example is an illustration and does not restrain this invention.

High-density polyethylene 79% by volume, melt flow rate 5g / 10min, polyester elastomer 5% by volume, modified high-density polyethylene 4% by volume, silicone-containing polyethylene 6% by volume, calcium carbonate whisker (aspect ratio: 3-50) 5% by volume Then, using 1% by volume of montanic acid ester as a raw material, pellets were formed by kneading and heat melting with a kneading apparatus of a twin screw extruder, and a test piece for measuring physical properties was formed by injection molding. The specimen for measuring physical properties was measured for flexural modulus according to the R scale of JISK7171, and measured for Rockwell hardness using the R scale according to the R scale of JISK7171. The dynamic friction coefficient is SUS axis, Al axis, non-lubricated at normal temperature and no lubrication with a surface pressure of 0.3 MPa and a speed of 10 m / min using the friction coefficient measuring apparatus shown in FIG.
The measurement was carried out by rotating a resin shaft (made of high impact polystyrene) for 20 hours using a counterpart material.

69% by volume of high-density polyethylene having a melt flow rate of 5 g / 10 min, 4% by volume of silicone elastomer, 2% by volume of calcium carbonate whisker, 20% by volume of low-density polyethylene containing oil components, 4% by volume of silicon dioxide containing silicone, montanic acid ester 1 A test piece for measuring physical properties was molded in the same manner as in Example 1 using the volume% as a raw material, and the physical properties were measured in the same manner as in Example 1.
<Comparative Example 1>

The same high-density polyethylene, polyester elastomer, maleic anhydride-modified high-density polyethylene, and calcium carbonate whisker as in Example 1 were used in the same manner as in Example 1 using 73% by volume, 15% by volume, 5% by volume, and 7% by volume as raw materials. A test piece for measuring physical properties was molded, and the physical properties were measured in the same manner as in Example 1.
<Comparative Example 2>

A test piece was prepared by injection molding using 84% by volume of the same high-density polyethylene as in Example 1, 15% by volume of silicone-containing polyethylene, and 1% by volume of montanic acid ester.
<Comparative Example 3>

A test piece for measuring physical properties was molded in the same manner as in Example 1, using 94% by volume of polyacetal resin with a melt flow rate of 9 g / 10 min, 5% by volume of modified high-density polyethylene, and 1% by volume of montanic acid ester. The physical properties were measured in the same manner as in 1.
<Comparative Example 4>

A test piece for measuring physical properties was molded in the same manner as in Example 1 using only the same high-density polyethylene as in Example 1, and the physical properties were measured in the same manner as in Example 1. Table 1 shows the measurement results of the examples, and Table 2 shows the measurement results of the comparative examples.

In addition, although “◯” in Table 1 and Table 2 indicates a pass, it is included until it passes the limit because it passes sufficiently. “△” indicates insufficient. “X” indicates failure.
Comparative Example 1 has a rigidity / elastic modulus ratio of 38, which is within the scope of the present invention, but because the dynamic friction coefficient was slightly higher than that of the base material of Comparative Example 4, it maintained high lubrication in a region exceeding 20 hours. And the aggressiveness against the plastic shaft was the boundary between passing and insufficient. In Comparative Example 3, the aggressiveness against the counterpart material peculiar to polyacetal resin was strong.

According to the present invention, high lubricity is maintained, and the aggressiveness against the mating member is reduced,
A sliding surface that has a slight change in friction over time and does not increase wear over time, and that maintains accurate, stable, and safe sliding over a long period of time. A resin-based sliding member provided and a sliding part / sliding device provided with such a sliding surface are provided.

It is a schematic explanatory drawing of the measuring apparatus of a dynamic friction coefficient.

Claims (4)

  It is a composite based on a self-lubricating thermoplastic olefin resin and has a ratio of at least Rockwell hardness (conforming to JISK7171 R scale) / flexural modulus (conforming to JISK7171) of 25- 45. A resin-based sliding member characterized by comprising a composite that provides a sliding surface having a lower friction coefficient than that of a base material.   Self-lubricating thermoplastic olefin-based resin composite that occupies 75% by volume or more, at least Rockwell hardness (conforming to JISK7171 R scale) / flexural modulus (conforming to JISK7171) A resin-based sliding member characterized in that it is made of a composite that provides a sliding surface having a friction coefficient of 25 to 45 and a lower friction coefficient than that of the base material. By injection molding, the resin-based sliding member is made into a sliding part / sliding device from a resin-based sliding member in which the base material of the self-lubricating thermoplastic olefin resin accounts for 75% by weight or more. From a composite that gives a slide type sliding surface whose well hardness (conforming to R scale of JISK7171) / flexural modulus (conforming to JISK7171) is 25 to 45 and whose friction coefficient is lower than that of the base material A sliding part / sliding device characterized by that. 3. The resin-based sliding member according to claim 1 or 2, comprising one or more of the following (1) to (3).
(1) The resin-based sliding member is made of a self-lubricating thermoplastic olefin resin as a base material.
Consists of more than 65% by volume.
(2) The self-lubricating thermoplastic olefin resin is made of a thermoplastic olefin resin having a density of medium density or higher.
(3) The composite has a friction coefficient that is 10% or more lower than the friction coefficient of the base material.