JP6865559B2 - Molding materials for sliding members, sliding members and their manufacturing methods - Google Patents

Description

The present invention relates to a molding material for a sliding member, a sliding member, and a method for manufacturing the same.

Conventionally, as a sliding member for industrial equipment, office equipment, transportation equipment, etc., it has excellent bending strength and sliding characteristics in a dry environment (for example, high wear resistance, low friction coefficient, etc.), and has excellent warpage and warpage. Metal sliding members that do not easily make noise when sliding are often used. However, in recent years, in order to meet the needs for miniaturization, cost reduction, and weight reduction of various devices, there is a tendency to replace metal sliding members with resin sliding members. Examples of the resin for the resin sliding member include a thermoplastic resin and a thermosetting resin, but the resin is made of a resin that replaces the conventional metal sliding member that has been used under high load conditions and high speed conditions. As the sliding member, a thermosetting resin that does not melt is more suitable from the viewpoint of shape retention, and a phenol resin having an excellent balance of heat resistance, dimensional accuracy, cost, and lightness is particularly preferable.

Further, by adding a fiber material such as glass fiber, organic fiber, or carbon fiber to the phenol resin, the sliding characteristics of the formed sliding member can be further improved. Examples of the molding material for a sliding member containing such a phenol resin and a fiber material include a molding material for a sliding member in which glass fiber and wax are mixed with a phenol resin (see Patent Document 1), a phenol resin, graphite, and the like. A molding material for a sliding member (see Patent Document 2) containing an aramid fiber having an average fiber length of 200 to 300 μm has been proposed.

However, the sliding member formed of the molding material for the sliding member containing the glass fiber described in Patent Document 1 is a component such as a pump for transporting air or liquid, and has a foreign substance such as sand or dust on the sliding surface. If it is used in a situation where it is easy to get caught, the surface will be finely scratched and wear will easily proceed. Further, the sliding member formed of the molding material for the sliding member containing the organic fiber described in Patent Document 2 has an effect of improving the mechanical strength and the sliding property by the aramid fiber, but the productivity is difficult. There is. Specifically, when injection molding is performed, the filling property of the thin-walled portion and the fine-walled portion tends to be low, and the aramid fiber tends to reduce the workability even when performing processing such as grinding. Further, when organic fibers or carbon fibers are used, another inconvenience that the cost performance of the sliding member is lowered may occur.

Therefore, it has been studied to use relatively inexpensive wood flour as a fiber material to be added to the phenol resin. As a molding material for a sliding member using wood powder, for example, a molding material for a sliding member containing 40 to 60% by mass of wood powder, 10 to 15% by mass of graphite, and 10 to 20% by mass of titanium oxide has been proposed. (See Patent Document 3).

However, the sliding member formed of the molding material for the sliding member of Patent Document 3 has insufficient bending strength and sliding characteristics in a dry environment as compared with the metal sliding member, and has insufficient warpage and warpage. The noise during sliding cannot be sufficiently suppressed. Therefore, it is difficult to completely replace the metal sliding member with the sliding member formed of the conventional molding material for the sliding member.

Japanese Unexamined Patent Publication No. 2006-328215 Japanese Unexamined Patent Publication No. 2004-24031 Japanese Unexamined Patent Publication No. 4-320443

The present invention has been made based on the above circumstances, and an object of the present invention is to have excellent bending strength and sliding characteristics in a dry environment, and to prevent warping and noise during sliding. An object of the present invention is to provide a molding material for a sliding member capable of forming a member.

The molding material for a sliding member made to solve the above problems contains phenol resin, graphite and wood powder, and the maximum particle size of the wood powder is 90 μm or more and 400 μm or less.

The molding material for the sliding member is made by adding graphite, which is a solid lubricant, and wood powder, which functions as a fiber material, to phenol resin, which is a base material, so that the maximum particle size of the wood powder is 90 μm or more and 400 μm or less. It was done. The molding material for the sliding member is made of wood on the surface of the sliding member formed by setting the maximum particle size of the wood powder to be equal to or less than the upper limit, that is, preventing the inclusion of relatively large wood powder. It is possible to suppress the deterioration of sliding characteristics due to the protrusion of powder. Further, the molding material for the sliding member ensures that the wood powder functions as a fiber material by setting the maximum particle size of the wood powder to be equal to or higher than the above lower limit, that is, by not making the particle size of the wood powder too small. As a result, the strength of the formed sliding member can be improved. As described above, the molding material for the sliding member has excellent bending strength and sliding characteristics in a dry environment by setting the maximum particle size of the wood powder in the above range, and warps and sounds during sliding. It is possible to form a sliding member that is less likely to squeal. Further, by using wood powder as the fiber material in the molding material for the sliding member, the strength can be improved while reducing the specific gravity of the formed sliding member.

The content of the wood flour with respect to 100 parts by mass of the phenol resin is preferably 15 parts by mass or more and 75 parts by mass or less. As described above, by setting the content of wood powder with respect to 100 parts by mass of the phenol resin in the above range, the productivity of the sliding member and the moldability at the time of injection molding or cutting can be improved.

The content of graphite with respect to 100 parts by mass of the phenol resin is preferably 10 parts by mass or more and 120 parts by mass or less. By setting the graphite content in the above range in this way, the wear resistance of the formed sliding member can be improved and the amount of wear during sliding can be further reduced, and the amount of wear during sliding can be further reduced. The squeal can be further suppressed.

The mass ratio of the wood flour to the graphite is preferably 0.4 or more and 4.5 or less. By setting the mass ratio of the wood powder to the graphite in the above range, the sliding characteristics and moldability of the formed sliding member can be improved in a well-balanced manner.

The molding material for the sliding member may further contain an inorganic filler. When the molding material for the sliding member further contains an inorganic filler, the strength of the formed sliding member can be improved by the reinforcing effect, and as a result, the bending strength and the sliding characteristics in a dry environment can be improved. Improvement and suppression of warpage can be achieved more reliably.

The inorganic filler may be calcium carbonate, aluminum hydroxide, talc, mica or a combination thereof. As described above, when the inorganic filler is calcium carbonate, aluminum hydroxide, talc, mica, or a combination thereof, the strength and sliding characteristics of the formed sliding member can be improved in a well-balanced manner.

Another invention made to solve the above problems is a sliding member formed of the above-mentioned molding material for a sliding member.

Since the sliding member is formed of the above-mentioned molding material for the sliding member, it is excellent in bending strength and sliding characteristics in a dry environment, and is less likely to warp and make noise during sliding.

Yet another invention made to solve the above problems is a method for manufacturing a sliding member, which comprises a step of molding the above-mentioned molding material for a sliding member.

By using the above-mentioned molding material for sliding members, the sliding member is excellent in bending strength and sliding characteristics in a dry environment, and is less likely to warp and make noise during sliding. Members can be manufactured easily and reliably.

According to the molding material for a sliding member, the sliding member, and the manufacturing method thereof of the present invention, the sliding member is excellent in bending strength and sliding characteristics in a dry environment, and is less likely to warp and make noise during sliding. Can be provided.

It is a schematic diagram which shows the abrasion resistance test performed in an Example.

Hereinafter, the molding material for the sliding member, the sliding member, and the manufacturing method thereof of the present invention will be described in detail.

<Molding material for sliding members>
The molding material for the sliding member contains phenol resin, graphite, and wood powder, and the maximum particle size of the wood powder is 90 μm or more and 400 μm or less. The molding material for a sliding member may contain other optional components as long as the effects of the present invention are not impaired. Hereinafter, each component will be described.

[Phenol resin]
Phenol resin is an oligomer made from phenols and aldehydes, and is cured by a curing step described later to form a three-dimensional crosslinked structure, resulting in an insoluble and infusible state. Examples of the phenol resin include novolak type phenol resin and resol type phenol resin. Examples of the resole-type phenol resin include methylol-type phenol resins and dimethylene ether-type phenol resins. Among these, dimethylene ether-type phenol resins are preferable from the viewpoint of making it difficult for chips to occur during processing. Among these, the novolak type phenol resin is preferable as the phenol resin from the viewpoint of improving the wear resistance of the sliding member to be formed. The phenol resin can be used alone or in combination of two or more.

Examples of the phenols include alkylphenols such as cresol, ethylphenol, xylenol, pt-butylphenol, octylphenol, nonylphenol and dodecylphenol, and p-phenylphenol and phenol. Of these, phenol is preferred. The above-mentioned phenols can be used alone or in combination of two or more.

Examples of the aldehydes include formaldehyde and paraformaldehyde. Of these, paraformaldehyde is preferred. The above aldehydes can be used alone or in combination of two or more.

As the lower limit of the number average molecular weight (Mn) of the phenol resin, 350 is preferable, and 450 is more preferable. On the other hand, as the upper limit of Mn, 1,200 is preferable, and 900 is more preferable. If the Mn of the phenol resin is smaller than the above lower limit, the heat shock resistance of the formed sliding member may be insufficient. On the contrary, when the Mn of the phenol resin exceeds the upper limit, the workability in manufacturing the molding material for the sliding member may be lowered. The number average molecular weight of the phenol resin and the weight average molecular weight described later are values measured by the area method of the gel filtration chromatograph.

The lower limit of the weight average molecular weight (Mw) of the phenol resin is preferably 400, more preferably 1,000, and even more preferably 1,500. On the other hand, the upper limit of the Mw is preferably 9,000, more preferably 5,000, and even more preferably 4,000. If the Mw of the phenol resin is smaller than the lower limit, it may be difficult to mold the sliding member. On the contrary, when the Mw of the upper limit phenol resin exceeds the above upper limit, the workability in manufacturing the molding material for the sliding member may be lowered.

The lower limit of the dispersion ratio (Mw / Mn) of the phenol resin is preferably 1.5, more preferably 3, and even more preferably 5. On the other hand, as the upper limit of the dispersion ratio, 20 is preferable, 15 is more preferable, and 10 is further preferable. By setting the dispersion ratio in the above range, the friction coefficient of the formed sliding member can be reduced, and as a result, the amount of wear during sliding can be further reduced.

The upper limit of the total content of the phenolic monomer and the phenolic dimer in the phenolic resin is preferably 20% by mass, more preferably 12% by mass, and even more preferably 6% by mass. On the other hand, the lower limit of the total content is, for example, 0.1% by mass. By setting the total content of the phenolic monomer and the phenolic dimer within the above range, the friction coefficient of the formed sliding member can be reduced. The total content of the phenolic monomer and the phenolic dimer is a value measured by the area method of the gel filtration chromatograph.

It is particularly preferable that the phenol resin has a dispersion ratio in the above range and a total content of the phenolic monomer and the phenolic dimer in the above range. By setting the dispersion ratio in the phenol resin and the total content of the phenol monomer and the phenol dimer within the above ranges, the friction coefficient of the formed sliding member can be further reduced, and as a result, sliding The amount of wear during time can be further reduced.

The lower limit of the content ratio of the phenol resin in the molding material for the sliding member is preferably 20% by mass, more preferably 30% by mass. On the other hand, the upper limit of the content ratio of the phenol resin is preferably 80% by mass, more preferably 70% by mass, and even more preferably 60% by mass. If the content ratio of the phenol resin is smaller than the lower limit, the moldability may be lowered. On the contrary, when the content ratio of the phenol resin exceeds the upper limit, other components such as graphite and wood powder may be insufficient, and the sliding characteristics of the formed sliding member may be deteriorated.

(Manufacturing method of phenol resin)
Examples of the method for producing the phenol resin include a step of preparing a mixed solution of phenols, aldehydes and a catalyst (preparation step), a step of condensing the prepared mixed solution at a reflux temperature (condensation reaction step), and the like. Examples thereof include a method including a step (removal step) of removing the monomer and the like from the mixed solution after the condensation reaction.

(Preparation process)
When synthesizing a novolak type phenol resin, examples of the catalyst include inorganic acids such as hydrochloric acid, sulfuric acid and phosphoric acid, organic acids such as oxalic acid, paratoluene sulfonic acid, benzene sulfonic acid and xylene sulfonic acid, and zinc oxide. Examples thereof include acid catalysts such as acidic inorganic salts such as zinc chloride, magnesium oxide and zinc acetate. Of these, inorganic acids are preferred, and phosphoric acid is more preferred. The molar ratio of aldehydes to phenols in the mixed solution is, for example, 0.75 or more and 0.95 or less.

When synthesizing a resole-type phenol resin, examples of the catalyst include an alkali catalyst such as an alkali metal hydroxide such as sodium hydroxide, potassium hydroxide, and lithium hydroxide. The molar ratio of aldehydes to phenols in the mixed solution is, for example, 1.1 or more and 4.0 or less.

The lower limit of the catalyst content in the mixed solution is, for example, 0.05 parts by mass, preferably 0.1 parts by mass, based on 100 parts by mass of the phenols. On the other hand, the upper limit of the content of the catalyst is, for example, 70 parts by mass and 50 parts by mass is preferable with respect to 100 parts by mass of phenols.

Additives such as ethylene glycol may be further added to the mixed solution. The content of the additive in the mixed solution is, for example, 40 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of phenols.

(Condensation reaction step)
The reaction time in the condensation reaction is, for example, 2 hours or more and 12 hours or less.

(Removal process)
As a method for removing the monomer and the like in the removing step, for example, a step of adding an organic solvent such as methylisobutylketone to the mixed solution after the condensation reaction to phase-separate the organic solvent layer (upper layer) and the aqueous solution layer (lower layer). A method including a step of washing the upper layer with water and a step of removing an organic solvent such as methylisobutylketone from the upper layer by vacuum distillation or the like, a method of removing water and a monomer by vacuum distillation from the mixed solution after the condensation reaction, etc. Can be mentioned.

[graphite]
Graphite functions as a solid lubricant that reduces the friction coefficient of the sliding member formed in the molding material for the sliding member. Since the molding material for the sliding member contains graphite, the friction coefficient can be stabilized when the formed sliding member shifts to steady wear. Examples of the graphite include natural graphite such as scaly graphite, scaly graphite, and earthy graphite, and artificial graphite. Among these, natural graphite is preferable, and earth-like graphite is more preferable. Graphite can be used alone or in combination of two or more.

The lower limit of the graphite content in the molding material for the sliding member is preferably 10 parts by mass, more preferably 15 parts by mass, and even more preferably 20 parts by mass with respect to 100 parts by mass of the phenol resin. On the other hand, the upper limit of the graphite content is preferably 120 parts by mass, more preferably 90 parts by mass, further preferably 80 parts by mass, and particularly preferably 70 parts by mass with respect to 100 parts by mass of the phenol resin. By setting the graphite content in the above range, the amount of wear of the formed sliding member during sliding can be reduced to further improve the wear resistance, and the squealing can be further suppressed. it can. If the graphite content is less than the lower limit, the wear resistance of the formed sliding member may decrease. On the contrary, when the graphite content exceeds the above upper limit, the strength of the formed sliding member may decrease or the amount of wear during sliding may increase.

[Wood flour]
The wood powder in the molding material for the sliding member is obtained by processing a tree into fine particles and mainly functions as a fiber material. Some wood powders are derived from softwoods or hardwoods, but it is preferable to include wood powders derived from softwoods because a relatively homogeneous powder can be obtained. Wood flour can be used alone or in combination of two or more.

By using graphite and wood powder in combination as the molding material for the sliding member, the friction coefficient can be reduced without lowering the wear resistance of the sliding member to be formed, and carbon fiber, glass fiber, etc. are used. Physical strength can be maintained without it. Further, while a sliding member using carbon fiber or glass fiber as a fiber material is difficult to process such as cutting, the sliding member formed by the molding material for the sliding member uses wood powder. Therefore, cutting is very easy.

The maximum particle size of the wood powder is 90 μm or more and 400 μm or less. By setting the maximum particle size of the wood powder in the above range, the molding material for the sliding member ensures that the wood powder functions as a fiber material, and the wood powder is formed on the surface of the sliding member. The sliding characteristics can be reduced due to the protrusion of the powder. As a result, it is possible to form a sliding member which is excellent in bending strength and sliding characteristics in a dry environment and is less likely to warp and make noise when sliding.

The lower limit of the maximum particle size of the wood powder is preferably 100 μm, more preferably 120 μm. On the other hand, the upper limit of the maximum particle size of the wood powder is preferably 360 μm, more preferably 300 μm. If the maximum particle size of the wood powder is smaller than the lower limit, the strength of the formed sliding member may be insufficient and the wear resistance may be lowered. On the contrary, when the maximum particle size of the wood powder exceeds the upper limit, the wood powder may hinder the friction of the formed sliding member, which may reduce the wear resistance or the warp may not be sufficiently suppressed. is there. Here, the "maximum particle size" means any 100 trees in the field of view when the molding material for forming the sliding member is observed with an electron microscope and the longest width of each wood powder is defined as the "particle size". Indicates the maximum value of particle size in powder.

Wood flour having a maximum particle size in the above range can be easily obtained by, for example, sieving. For example, wood flour having a maximum particle size of 180 μm can be obtained by sieving wood flour as a raw material using a sieve having an opening of 180 μm. The maximum particle size of wood powder can also be measured by a laser diffraction type particle size distribution measuring device before it is added to the molding material for sliding members.

The lower limit of the content of the wood powder in the molding material for the sliding member is preferably 15 parts by mass, more preferably 25 parts by mass, and even more preferably 30 parts by mass with respect to 100 parts by mass of the phenol resin. On the other hand, as the upper limit of the content of the wood flour, 75 parts by mass is preferable, 60 parts by mass is more preferable, and 55 parts by mass is further preferable. If the content of wood powder is less than the above lower limit, it may be difficult to mold the sliding member and the productivity may decrease. On the contrary, when the content of wood powder exceeds the above upper limit, the wood powder inhibits the friction of the formed sliding member, which may reduce the wear resistance. In addition, the warpage of the formed sliding member may not be sufficiently suppressed, or the sliding member may be difficult to mold and the productivity may decrease.

Further, the graphite content and the wood powder content in the molding material for the sliding member are constant from the viewpoints of improving the sliding characteristics of the formed sliding member, bending strength, etc., and suppressing warpage. It is preferably within the range of. Specifically, the lower limit of the mass ratio of wood powder (wood powder / graphite) to graphite in the molding material for the sliding member is preferably 0.4, more preferably 0.5, and even more preferably 0.6. .. On the other hand, as the upper limit of the mass ratio of wood flour to graphite, 4.5 is preferable, 3.5 is more preferable, and 2.5 is further preferable.

[Inorganic filler]
The molding material for the sliding member preferably further contains an inorganic filler. When the molding material for the sliding member further contains an inorganic filler, the strength of the formed sliding member can be further improved by the reinforcing effect. The inorganic filler may be used alone or in combination of two or more.

The inorganic filler is not particularly limited, and an inorganic filler commonly used in conventional phenol resin molding materials may be appropriately used, and for example, a spherical filler, a plate-shaped filler, or the like can be used. Examples of the spherical filler include those derived from calcium carbonate, barium sulfate, calcium sulfate, aluminum hydroxide, clay, pearlite, silas balloon, diatomaceous earth, calcined alumina, calcium silicate and the like. Examples of the plate-shaped filler include talc and mica. Of these, calcium carbonate, aluminum hydroxide, talc and mica are particularly preferable from the viewpoint of suppressing the influence on wear characteristics. When the molding material for the sliding member contains calcium carbonate, aluminum hydroxide, talc, mica or a combination thereof, the strength and sliding characteristics of the formed sliding member can be improved in a well-balanced manner. In addition, in this specification, it is assumed that the inorganic filler does not contain a fiber filler.

When the molding material for the sliding member contains an inorganic filler, the lower limit of the content of the inorganic filler is preferably 30 parts by mass and more preferably 40 parts by mass with respect to 100 parts by mass of the phenol resin. On the other hand, as the upper limit of the content of the inorganic filler, 70 parts by mass is preferable, and 60 parts by mass is more preferable. If the content of the inorganic filler is less than the above lower limit, the wear resistance of the formed sliding member may decrease. On the contrary, when the content of the inorganic filler exceeds the upper limit, the friction coefficient of the formed sliding member may increase.

(Other optional ingredients)
The molding material for the sliding member may further contain other optional components. Examples of the other optional components include fiber materials other than the above wood flour, curing agents, fillers, mold release agents, curing accelerators, coupling agents, solvents and the like.

Examples of the other fiber materials include organic fibers such as aramid fibers, glass fibers, and carbon fibers. The upper limit of the content of the other fibers in the molding material for the sliding member is preferably 10 parts by mass and more preferably 1 part by mass with respect to 100 parts by mass of the phenol resin. If the content of the other fiber material exceeds the above upper limit, the processability of the molding material for the sliding member may decrease or the raw material cost may increase. In particular, for a relatively hard fiber material such as glass fiber, if the blending amount is too large, the amount of wear of the mating material may increase during sliding, so it is desirable to suppress the addition as much as possible.

The curing agent accelerates the curing reaction of the phenol resin. When the phenol resin is a novolak type phenol resin, the molding material for the sliding member usually contains a curing agent. Examples of the curing agent include hexamethylenetetramine and the like. When the molding material for a sliding member contains a curing agent, the lower limit of the content of the curing agent is preferably 5 parts by mass with respect to 100 parts by mass of the phenol resin. On the other hand, the upper limit of the content is preferably 20 parts by mass.

The filler improves the strength, durability, wear resistance, etc. of the sliding member to be formed. Examples of the filler include carbon materials other than graphite, elastomers, PTFE (polytetrafluoroethylene) and the like.

The release agent improves the releasability of the formed sliding member. Examples of the release agent include calcium stearate, zinc stearate and the like. The content of the mold release agent in the molding material for the sliding member can be, for example, 0.2 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the phenol resin.

The curing accelerator further accelerates the curing reaction of the phenol resin. Examples of the curing accelerator include magnesium oxide and slaked lime.

[Manufacturing method of molding material for sliding members]
The method for producing the molding material for the sliding member is not particularly limited, and a known method for producing the molding material for the sliding member can be adopted. Specifically, for example, the above-mentioned various components are heated and melted by a pressure kneader, a mixing roll, a twin-screw extruder or the like and kneaded, and then the obtained kneaded product is molded into a sheet shape, and this sheet-shaped molded product is further obtained. Examples thereof include a method of crushing using a pelletizer, a power mill and the like. The kneaded product can be used as it is for molding as a molding material for the sliding member.

<Sliding member>
The sliding member is formed from the above-mentioned molding material for the sliding member. The shape of the sliding member is not particularly limited, and examples thereof include a disk shape, a square plate shape, a columnar shape, a prismatic shape, and a ring shape. The application of the sliding member is not particularly limited, but suitable ones include, for example, thrust washers, pulleys, bearings, gears, bearings, pump parts, swash plates, and the like.

<Manufacturing method of sliding member>
The method for manufacturing the sliding member includes a step (molding step) of molding the above-mentioned molding material for the sliding member. It is preferable that the method for manufacturing the sliding member further includes a step (curing step) of curing the phenol resin contained in the molding material for the sliding member at the same time as the molding step or after the molding step. The method for manufacturing the sliding member may further include a step of melt-kneading the molding material for the sliding member (melt-kneading step) before the molding step.

(Melting and kneading process)
As a method of melt-kneading the molding material for a sliding member, for example, the same method as the melt-kneading in the above-mentioned method for manufacturing a molding material for a sliding member can be used.

(Molding process)
In this step, the molding material for the sliding member is molded. The method for molding the molding material for the sliding member is not particularly limited, and examples thereof include injection molding, transfer molding, and compression molding. Of these, injection molding is preferred. When molding by injection molding, the temperature of the front part of the cylinder can be, for example, 70 ° C. or higher and 120 ° C. or lower. The temperature of the rear part of the cylinder can be, for example, 30 ° C. or higher and 60 ° C. or lower.

(Curing process)
In this step, the phenol resin contained in the molding material for the sliding member is cured. Examples of the method of curing the phenol resin include a method of heating a molded product obtained in a molding step. The heating temperature can be, for example, 150 ° C. or higher and 200 ° C. or lower. The heating time can be, for example, 30 seconds or more and 90 seconds or less.

The molded product obtained by the molding step or the cured product obtained by the curing step can be used as it is as a sliding member, but it is preferable to use it as a sliding member after aftercuring. By applying aftercure, the sliding characteristics and dimensional accuracy can be improved. Examples of the aftercure method include a method of heating the molded product or the cured product. The heating temperature can be, for example, 150 ° C. or higher and 230 ° C. or lower. The heating time can be, for example, 3 hours or more and 24 hours or less.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to the following Examples.

First, the novolak-type phenol resin, wood powder, and inorganic filler used in this example will be described.

[Manufacturing of novolak type phenolic resin]
In a reaction vessel equipped with a thermometer, agitator and a condenser, 193 parts by mass of phenol, 142 parts by mass of 37% by mass formalin (formaldehyde / molar ratio of phenol: 0.85) and 0.97 parts by mass of oxalic acid (of phenol). After charging 0.5% by mass with respect to the blending amount, the temperature was gradually raised to the reflux temperature (98 to 102 ° C.), and the condensation reaction was carried out at the same temperature for 6 hours. Then, when the mixture was concentrated under reduced pressure, 199 parts by mass (103% by mass with respect to the amount of phenol charged) of a novolak type phenol resin was obtained. This novolak type phenol resin had a number average molecular weight of 512, a weight average molecular weight of 3,842, and a dispersion ratio of 7.5.

[Wood flour]
Wood flour A (maximum particle size 360 μm): Sanwa cellulosin sieved with a 40 mesh sieve Wood flour B (maximum particle size 180 μm): Sanwa cellulosin sieved with an 80 mesh sieve Wood flour C (maximum grain size) Diameter 100 μm): Sanwa Cellulosin, sieved with 170 mesh sieve Wood flour X (maximum particle size 500 μm): Sanwa Cellulosin, sieved with 32 mesh sieve Wood flour Y (maximum particle size 80 μm): Sanwa Sieve with a 200 mesh sieve made of cellulosin

[Inorganic filler]
Aluminum hydroxide (manufactured by Showa Denko)
Talc (made by Japan Talc)
Mica (manufactured by Topy Industries)

<Manufacturing of molding materials for sliding members>
[Example 1]
As shown in Table 1 below, 100 parts by mass of novolak type phenol resin, 23 parts by mass of graphite (graphite) (“Blue PA” manufactured by Nippon Graphite Industries), and 45 parts by mass of wood flour A (maximum particle size 360 μm). , 45 parts by mass of calcium carbonate (manufactured by Maruo Calcium) as an inorganic filler, 14 parts by mass of hexamethylenetetramine as a curing agent, and 1 part by mass of calcium stearate as a release agent were mixed and mixed uniformly. Next, the obtained mixture was uniformly heated and kneaded with a hot roll to form a sheet, cooled, and then pulverized with a power mill to obtain a granule-shaped molding material for a sliding member.

A plate-shaped test piece was obtained by injection molding and curing the obtained molding material for a sliding member of Example 1 under the following molding conditions.
(Molding condition)
Cylinder temperature: front 90 ° C, rear 40 ° C
Mold temperature: 170 ℃
Curing time: 60 seconds

[Examples 2 to 13 and Comparative Examples 1 to 3]
In Example 1, the same operations as in Example 1 were carried out except that the types and contents of the phenol resin, wood powder, graphite and inorganic filler were as shown in Table 1, and Examples 2 to 13 and Comparative Example 1 were operated. To 3 molding materials for sliding members and test pieces were manufactured.

<Evaluation>
Using the obtained test piece, warpage, bending strength, wear resistance and squeal were evaluated according to the following method. The evaluation results are also shown in Table 1.

[Bending strength]
The bending strength of each test piece was measured according to JIS-K6911: 2006. The bending strength can be evaluated as "A (good)" when it is 80 MPa or more, and as "B (not good)" when it is less than 80 MPa.

[warp]
A strip-shaped member of 10 mm × 150 mm × 3 mm was cut out from each test piece and placed on a flat test table with one surface facing down. In a state where the surface around one end of the strip-shaped member in the long side direction is fixed to the test table, the warp at the other end raised from the test table (the lower surface of the strip-shaped member at the other end). And the distance from the surface of the test stand) were measured with a feeler gauge. The warp was measured at n = 3, and the average value was evaluated as "A (particularly good)", "B (good)" or "C (not good)" according to the following criteria.
A: 0.04 mm or less B: More than 0.04 mm and less than 0.10 mm C: 0.10 mm or more

[Abrasion resistance test]
The wear resistance of each test piece was measured with a thrust tester (“AFT-6A” manufactured by Azumahaka Precision Industries). Specifically, as shown in FIG. 1, a plate-shaped test piece X1 and a cylindrical mating member X2 arranged on the upper surface of the test piece X1 are arranged in a thrust tester (not shown). The mating member X2 is a hollow cylindrical carbon steel (S45C) having an outer diameter of 26.6 mm, an inner diameter of 20 mm, and a height of 15 mm. The space between the test piece X1 and the mating member X2 was unlubricated (dry environment). The mating member X2 was rotated in a certain direction B while applying a test surface pressure A from above. The test conditions were a test surface pressure A of 0.49 MPa, a test speed of 1.34 m / s, and a test time of 1 hour. After the test, the amount of wear (mm ³ ) was multiplied by the sliding distance (m) (the value obtained by multiplying the test speed by the test time) and the load (N) (test surface pressure A multiplied by the contact area of the test piece X1 and the mating member X2). The specific wear amount was calculated by dividing by (value). Abrasion resistance can be evaluated as "A (good)" or "B (not good)" based on the following criteria.
A: Specific wear amount is ^{less than 10 × 10-5} mm ³ / N ・ m B: Specific wear amount is 10 × ^10-5 mm ³ / N ・ m or more

[Sound]
In the test shown in FIG. 1, the generation of squealing when the speed and load were constant was measured with an acoustic vibration measuring machine (“NL-21” manufactured by Rion Co., Ltd.). The distance between the measurement position and the sliding part was 20 cm. The squeal was evaluated as "A (particularly good)", "B (good)" or "C (not good)" based on the following criteria.
A: No squealing was observed from beginning to end (70 dB or less, which is the driving sound of the test equipment).
B: A minute squeal was observed (more than 70 dB and less than 90 dB).
C: The occurrence of intense squealing was observed from beginning to end (90 dB or more).

As is clear from the results in Table 1 above, the molding materials for sliding members of the examples containing phenol resin, graphite, and wood powder having a maximum particle size of 90 μm or more and 400 μm or less have bending strength, warpage, and abrasion resistance. And, it was possible to form a test piece in which both the evaluations of the squeal and the squeal were good or particularly good. On the other hand, the molding material for sliding members of Comparative Examples 1 and 2 in which the maximum particle size of the wood powder is less than 90 μm or more than 400 μm is good at least one of the evaluations of bending strength, warpage, wear resistance and squeal. It wasn't. Further, the molding material for the sliding member of Comparative Example 3 in which graphite was not used did not have good evaluation of wear resistance and squeal.

According to the molding material for a sliding member, the sliding member, and the manufacturing method thereof of the present invention, the sliding member is excellent in bending strength and sliding characteristics in a dry environment, and is less likely to warp and make noise during sliding. Can be provided.

X1 test piece X2 mating member

Claims (4)

Contains phenolic resin, graphite and wood powder,
Maximum particle size of the wood flour Ri der than 400μm or less 90 [mu] m,
The content of the wood flour with respect to 100 parts by mass of the phenol resin is 15 parts by mass or more and 75 parts by mass or less.
The content of the graphite with respect to 100 parts by mass of the phenol resin is 10 parts by mass or more and 120 parts by mass or less.
Contains more inorganic filler,
The inorganic filler, calcium carbonate, aluminum hydroxide, talc, mica or molding material for these Kumiawasedea Ru sliding member. The molding material for a sliding member according to claim 1 , wherein the mass ratio of the wood powder to the graphite is 0.4 or more and 4.5 or less. A sliding member formed of the molding material for a sliding member according to claim 1 or 2. A method for manufacturing a sliding member, comprising a step of molding the molding material for the sliding member according to claim 1 or 2.

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