WO2015093443A1 - Sliding member resin composition, and sliding member - Google Patents

Abstract

　The purpose of the present invention is to provide a resin composition which enables the use of an easily and inexpensively obtainable resin and facilitates mass production, and with which it is possible to form a sliding member having excellent sliding properties including wear resistance. This sliding member resin composition includes a thermoplastic resin, graphite, and a boron-based compound. Said thermoplastic resin is preferably a polyphenylene sulfide, a polyamide, a polyether ether ketone, or a combination of these, and is more preferably a polyether ether ketone. The content of said boron-based compound is preferably between 0.2 to 5 parts by mass, inclusive, with respect to 100 parts by mass of said thermoplastic resin. At least one of the boron-based compound and graphite may be partially or entirely included in a resin powder that contains phenol resin and at least one of the boron-based compound and graphite. The maximum particle size of said resin powder is preferably 0.04 mm or less.

Description

Resin composition for sliding member and sliding member

The present invention relates to a resin composition for a sliding member and a sliding member.

Examples of the resin composition for the sliding member include those containing heat-resistant polyamide or polyphenylene sulfide as a resin component.

As a resin composition containing polyamide, there is a resin composition containing, as a main component, a polyamide having a melting point of 270 ° C. or higher, and a certain amount of a solid lubricant and a resin powder of metaphenylene isophthalamide (Japanese Patent Laid-Open No. Hei 6). -32978). However, this resin composition must use a polyamide having a melting point of 270 ° C. or higher or a special aromatic polyamide powder. Therefore, it is difficult to prepare a large amount of material, which is not suitable for mass production, and the cost of the material becomes high.

On the other hand, the resin composition containing polyphenylene sulfide has (B) fixed carbon of 98% or more, average particle diameter of 1 to 20 μm, and crystallinity of 80 with respect to 100 parts by weight of (A) polyphenylene sulfide. Some contain 1 to 200 parts by weight of graphite in the range of ˜92% (see JP-A-7-11135). However, although the sliding characteristics are improved by adding graphite, the current situation is that the addition of graphite alone is not sufficient for applications requiring higher sliding characteristics.

JP-A-6-32978 JP 7-11135 A

The present invention has been made on the basis of the above-described circumstances, and can use inexpensive and easily available resins, is easy to mass-produce, and has excellent sliding characteristics such as wear resistance. It aims at providing the resin composition which can form a member.

The invention made in order to solve the above problems is a resin composition for a sliding member containing a thermoplastic resin, graphite and a boron compound.

According to the resin composition for a sliding member of the present invention, since the boron compound suppresses oxidation of graphite by containing graphite and a boron compound, sliding properties such as wear resistance can be improved. Thereby, the temperature rise by the friction in the sliding member formed from the said resin composition for sliding members is suppressed.

As the thermoplastic resin, polyphenylene sulfide, polyamide, polyether ether ketone, and combinations thereof are preferable, and polyether ether ketone is more preferable. These resins are materials that are easily and inexpensively available compared to conventional metaphenylene isophthalamide and the like. Therefore, since it becomes easy to prepare a large amount of materials by using these resins, mass production is possible and manufacturing cost can be reduced.

The content of the boron compound is preferably 0.2 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the thermoplastic resin. By making the content of the boron-based compound in the above range, it is possible to more reliably obtain high sliding characteristics due to the inclusion of the boron-based compound.

The whole or a part of at least one of the boron compound and the graphite may be contained as a resin powder containing at least one of the boron compound and the graphite and a phenol resin. By including all or part of the boron compound and the graphite as a resin powder, the sliding characteristics are further improved. Moreover, since the resin powder containing a phenol resin can be easily and inexpensively formed from an available material, an increase in material cost can be suppressed as compared with the case where a special aromatic polyamide powder or the like is used.

The maximum particle size of the resin powder is preferably 0.04 mm or less. By setting the maximum particle size of the resin powder to 0.04 mm or less, the resin powder can be appropriately dispersed, and the effect of improving the sliding characteristics can be obtained more reliably.

The resin powder is preferably formed from a sprue, runner or molding failure product generated during molding, or a used molded product. By using sprue or the like generated during molding as a resin powder or a used molded product, the manufacturing cost can be reduced and the waste can be effectively used, so the environmental load can be reduced.

As the boron compound, boric acid, zinc borate, boron oxide, and combinations thereof are preferable, and boric acid is more preferable. By including the specific compound as the boron-based compound, the effect of improving the sliding characteristics can be obtained more reliably.

The present invention includes a sliding member using the resin composition for a sliding member. Since the sliding member is made of the resin composition for the sliding member, the sliding member is excellent in sliding characteristics such as wear resistance, and the temperature rise due to friction is suppressed.

According to the present invention, sliding characteristics such as wear resistance can be improved by containing graphite and a boron compound. Thereby, the temperature rise by the friction in the sliding member formed from the said resin composition for sliding members is suppressed.

Hereinafter, the resin composition for a sliding member and the sliding member of the present invention will be described.

[Resin composition for sliding member]
The resin composition for sliding members of the present invention contains (A) a thermoplastic resin, (B) graphite, and (C) a boron-based compound. The sliding member resin composition may contain an optional component as long as the effects of the present invention are not impaired.

<(A) Thermoplastic resin>
(A) A thermoplastic resin is the main component (base resin) of the resin component in the resin composition for sliding members. Here, the main component of the resin component is a component having the largest mass-based content in the resin component contained in the resin composition for sliding members, and occupies, for example, 50% by mass or more in the resin component. Refers to resin. (A) Examples of the thermoplastic resin include polyethylene (PE), polyamide (PA), modified polyphenylene ether (mPPE), polycarbonate (PC), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyphenylene sulfide (PPS). , Polyetheretherketone (PEEK), polyallyletherketone, polyamideimide (PAI), polyimide (PI), polyetherimide (PEI), polysulfone (PSU), polyethersulfone (PES), liquid crystal polymer (LCP), A fluororesin (PFA, EPA) etc. are mentioned. Examples of the polyamide (PA) include aliphatic polyamides such as nylon 6, nylon 11, nylon 12, nylon 46, nylon 410, nylon 66, nylon 610, nylon 612; nylon 6T, nylon 6I, nylon 9T, nylon M5T, nylon Examples include semi-aromatic polyamides such as MDX6.

(A) The lower limit of the melting point of the thermoplastic resin is preferably 200 ° C. (A) Since the melting point of the thermoplastic resin is 200 ° C. or higher, the resin composition for sliding members can be applied to high-temperature applications and high-load applications, and the sliding members are mass-produced by injection molding. It becomes possible. Examples of the thermoplastic resin (A) having such a melting point include nylon 6, nylon 46, nylon 410, nylon 66, nylon 610, nylon 612, nylon 6T, nylon 6I, nylon 9T, nylon M5T, nylon MDX6, and polyphenylene. Examples thereof include sulfide (PPS) and polyether ether ketone (PEEK).

The sliding member resin composition may contain one of these resins alone or two or more. (A) As a thermoplastic resin, PPS, PA, PEEK, and these combination are preferable, PPS, nylon 6, nylon 46, nylon 66, and PEEK are more preferable, and PEEK is further more preferable. PPS has excellent properties as engineering plastics such as excellent heat resistance, flame retardancy, toughness, and chemical resistance, and is widely used for various electrical parts, mechanical parts, automotive parts, etc. mainly for injection molding. it can. In addition, although there exist a bridge | crosslinking type and a linear type in PPS, a bridge | crosslinking type is more preferable since it is hard to produce the burr | flash at the time of shaping | molding, and is excellent in the workability | operativity in manufacture of a sliding member. Nylon 6, nylon 46 and nylon 66 have a low coefficient of friction and are excellent in heat resistance, toughness, wear resistance, and the like, and thus are suitable for housings, gears, and the like. PEEK has an extremely high continuous use temperature of 260 ° C., a low coefficient of friction, and excellent mechanical strength, chemical characteristics, and wear resistance. Therefore, PEEK is suitable for various sliding parts that require high temperature characteristics.

The lower limit of the content of the thermoplastic resin (A) in the resin composition for sliding members is preferably 25% by mass, and more preferably 50% by mass. Moreover, as an upper limit of the said content, 95 mass% is preferable and 90 mass% is more preferable. (A) If the content of the thermoplastic resin is less than the lower limit, it may be difficult to form a sliding member by injection molding or extrusion molding. On the other hand, when the content of the thermoplastic resin (A) exceeds the above upper limit, there is a possibility that sufficient sliding property cannot be imparted to the sliding member obtained from the sliding member resin composition. Moreover, as a minimum of content of the (A) thermoplastic resin in the resin component of the said resin composition for sliding members, 50 mass% is preferable and 75 mass% is more preferable. In addition, 100 mass% may be sufficient as content of the (A) thermoplastic resin in the resin component of the said resin composition for sliding members.

In addition, the said resin composition for sliding members may contain resin components other than (A) thermoplastic resin in the range of less than 50 mass%, for example. The resin component other than the (A) thermoplastic resin may exist in a powder form separately from the (A) thermoplastic resin, or may be compatible with the (A) thermoplastic resin. Further, (A) a resin powder containing at least one of (B) graphite and (C) boron-based compound is used as a resin component other than the thermoplastic resin, and (B) graphite and (C) boron-based compound are used. You may mix | blend as a component of the said resin composition for sliding members in the state which made the resin powder contain a part or all of this content. As a resin component other than the thermoplastic resin (A) in this case, a phenol resin is preferable as described later.

<(B) Graphite>
(B) Graphite improves sliding characteristics such as a low friction coefficient in the sliding member. As a minimum of content of this (B) graphite with respect to 100 mass parts of (A) thermoplastic resins, 10 mass parts are preferred and 20 mass parts are more preferred. On the other hand, the upper limit of the content of (B) graphite relative to 100 parts by mass of (A) thermoplastic resin is preferably 50 parts by mass, and more preferably 40 parts by mass. (B) If the graphite content is less than the lower limit, the dynamic friction coefficient of the sliding member may not be sufficiently reduced. On the other hand, if the content of (B) graphite exceeds the above upper limit, the wear amount of the sliding member may not be suppressed. In addition, although (B) graphite can be divided roughly into natural graphite (flaky graphite, scaly graphite, soil graphite, etc.) and artificial graphite, any graphite may be used as long as it has the above-mentioned characteristics.

<(C) Boron-based compound>
(C) The boron-based compound (B) suppresses oxidation of graphite and improves sliding characteristics such as a low friction coefficient in the sliding member. Examples of such (C) boron compounds include compounds containing boron atoms and oxygen atoms, such as boric acid, borates, borate esters, boron oxide, and borax. Examples of boric acid include orthoboric acid, metaboric acid, and tetraboric acid. Examples of borates include salts of boric acid such as orthoboric acid, metaboric acid, and tetraboric acid. Specifically, sodium salts, potassium salts, magnesium salts, zinc salts, lead salts of these boric acids, Examples thereof include lithium salt, aluminum salt, potassium salt, ammonium salt, cadmium salt, silver salt, copper salt, nickel salt, barium salt, bismuth salt, manganese salt and the like. Examples of the boric acid ester include trimethyl borate, triethyl borate, triphenyl borate and the like. Among these, boric acid compounds such as boric acid and borates, boron oxide and combinations thereof are preferable, boric acid, potassium borate, zinc borate, copper borate, bismuth borate, boron oxide and these. A combination is more preferable, and boric acid, zinc borate, boron oxide, and combinations thereof are more preferable. Of these, boric acid is most preferable because it has a melting point as low as 184 ° C. and melts and uniformly disperses when the raw material is heated and kneaded in the production of the resin composition for sliding member properties. These boron compounds may be used alone or in combination of two or more.

(A) As a minimum of content of (C) boron system compound to 100 mass parts of thermoplastic resins, 0.2 mass part is preferred, 0.5 mass part is more preferred, and 1.0 mass part is still more preferred. On the other hand, the upper limit of the content of the (C) boron compound with respect to 100 parts by mass of (A) thermoplastic resin is preferably 5 parts by mass, more preferably 4 parts by mass, and even more preferably 3 parts by mass. When the content of the (C) boron compound is less than the lower limit, the effect of improving the sliding characteristics due to the addition of the (C) boron compound may not be sufficiently obtained. On the other hand, if the content of (C) the boron-based compound exceeds the above upper limit, the fluidity of the resin tends to decrease during the melt extrusion of the material, which may impair the manufacturing stability and workability of the sliding member. There is. Further, from the viewpoint of further reducing (B) the oxidation of graphite and further suppressing the progress of wear, the content of (C) boron-based compound is preferably less than an equimolar amount with respect to the structural unit of (B) graphite. .

<(D) Optional component>
As described above, the resin composition for a sliding member may contain (D) an optional component in addition to (A) the thermoplastic resin, (B) graphite, and (C) the boron-based compound. Examples of the optional component (D) include a curing agent (such as hexamethylenetetramine), a mold release agent (such as calcium stearate and zinc stearate), a curing accelerator (such as magnesium oxide and slaked lime), and a solid lubricant ( For example, polytetrafluoroethylene etc.), a coupling agent, a thermosetting resin powder, a solvent, etc. are mentioned. In addition to these, a known elastomer or filler may be included as long as the effects of the present invention are not impaired. Examples of the elastomer include acrylonitrile butadiene rubber (NBR), urethane rubber, styrene-butadiene rubber (SBR), and acrylic rubber. Examples of the filler include calcium carbonate, clay, talc, silica, alumina, carbon fiber, and aramid fiber. (D) An arbitrary component may be used individually by 1 type, or may use 2 or more types together.

<Method for Preparing Resin Composition for Sliding Member>
The sliding member resin composition comprises (A) a thermoplastic resin, (B) graphite and (C) a boron-based compound, and if necessary, (A) a resin component other than the thermoplastic resin and other optional components. It can be prepared by mixing. This mixing can be performed using, for example, a known mixer. Moreover, it can also prepare by heat-kneading with a biaxial extruder.

(B) Graphite and (C) boron compound may be mixed with (A) thermoplastic resin as they are. You may mix as (E) resin powder containing at least one of a system compound.

<(E) Resin powder>
(E) The resin component of the resin powder may be a thermoplastic resin or a thermosetting or photocurable resin, but a phenol resin, urea resin, melamine resin, unsaturated polyester, epoxy resin, etc. The thermosetting resin is preferable, and a phenol resin described later is more preferable as a main component. Thus, by adding at least one of (B) graphite and (C) boron-based compound as a resin powder containing at least one of boron-based compound and graphite and a phenol resin, conventional graphite is added. The above-described wear-inhibiting effect can be obtained when only the additive is added, and the temperature rise due to friction of the material can be suppressed.

(B) When a part of the graphite and (C) boron-based compound is mixed as the resin powder (E), the total content of the component (B) and the component (C) in the resin composition for a sliding member ( E) As a minimum of the content rate of the total content of (B) component and (C) component mixed as resin powder, 20 mass% is preferred and 80 mass% is more preferred. When the said content rate is more than the said minimum, while being able to suppress wear more effectively, the temperature rise by friction of material can be suppressed more effectively.

(E) The shape of the resin powder is not particularly limited, and examples thereof include a spherical shape, a needle shape, a rod shape, and a plate shape. Moreover, as an upper limit of the maximum particle size of (E) resin powder, 0.04 mm is preferable and 0.03 mm is more preferable. (E) By making the maximum particle size of the resin powder not more than the above upper limit, the (E) resin powder can be appropriately dispersed in the resin composition for a sliding member, and the effect of improving the sliding characteristics can be further improved. You can definitely get it. On the other hand, if the maximum particle size of (E) resin powder exceeds the above upper limit, the variation in particle size of (E) resin powder tends to cause unevenness in performance, resulting in a decrease in mechanical properties of the sliding member. May occur. Further, the lower limit of the maximum particle size is preferably 0.01 mm from the viewpoint of more reliably obtaining the effect of improving the sliding characteristics. Here, the “maximum particle size” of the resin powder (E) is the maximum value of the particle size measured using a laser scattering diffraction type particle size distribution measuring device.

(E) The resin powder may be separately formed for the resin composition for the sliding member, but the resin composition contains at least one of (B) graphite and (C) boron-based compound. You may divert a thing. Specifically, sprues, runners or molding defects generated during molding, or used molded articles can be used. As described above, (E) by using sprue generated during molding as a resin powder or a used molded product, the manufacturing cost can be reduced, and the waste can be effectively used, so that the environmental load can be reduced.

(Phenolic resin)
Although there is no restriction | limiting in particular as a phenol resin, The phenol resin currently used conventionally as a material of a sliding member is preferable. Examples of such a phenolic resin include novolak type phenolic resins and resol type phenolic resins. Among these, novolac type phenolic resins are preferable in that the amount of wear is reduced and the PV value described later is increased. Examples of the resol type phenol resin include a methylol type and a dimethylene ether type. Among these, a dimethylene ether type phenol resin is preferable in that the occurrence of chipping during processing is small. These phenol resins may be used alone or in combination of two or more.

(A) As a minimum of content of (E) resin powder to 100 mass parts of thermoplastic resins, 8 mass parts are preferred, 10 mass parts are more preferred, and 25 mass parts are still more preferred. On the other hand, the upper limit of the content of (E) resin powder with respect to 100 parts by mass of (A) thermoplastic resin is preferably 260 parts by mass, more preferably 160 parts by mass, and even more preferably 100 parts by mass. (E) When the content of the resin powder is less than the above lower limit, the content of at least one of (B) graphite and (C) boron-based compound is insufficient and the friction coefficient of the sliding member is reduced. You may not be able to. On the other hand, when the content of the resin powder (E) exceeds the upper limit, when the sliding member is molded by melt extrusion or the like using the sliding member resin composition, Since the fluidity tends to decrease, the manufacturing stability and workability of the sliding member may be impaired.

In addition, even when all or part of at least one of (B) graphite and (C) boron-based compound is contained as (E) resin powder, (B) graphite in the resin composition for sliding member And (C) The content of the boron-based compound is preferably in the above-described range.

In addition, resin powder such as phenol resin powder may be added as an optional component (D) without containing (B) graphite and (C) boron-based compound. Moreover, you may make resin powder, such as a phenol resin powder, contain the arbitrary components illustrated previously, such as a hardening | curing agent, and may make it contain as (D) arbitrary components.

[Sliding member]
The sliding member of the present invention is formed using the sliding member resin composition. Since the said sliding member uses the above-mentioned resin composition for sliding members, it is excellent in sliding characteristics, such as abrasion resistance, and the temperature rise by friction is suppressed.

The sliding member is not particularly limited. For example, a shaft, a bearing, a piston of an internal combustion engine, a piston ring, a piston pin, a cylinder, a brake pad, a thrust washer, a pulley, a gear, a gear, a pump component, a slant A board etc. are mentioned.

Hereinafter, the present invention will be described with reference to examples. However, the present invention is not limited to the examples described below. In the examples, “%” indicates “mass%” unless otherwise specified.

[Production of resin powder]
In a reaction vessel equipped with a thermometer, a stirrer and a condenser, 193 parts by mass of phenol (P), 57 parts by mass of 92% paraformaldehyde (F) (F / P (molar ratio) = 0.85), 89 116% by mass of phosphoric acid (60 parts by mass with respect to 100 parts by mass of phenol) and 96.5 parts by mass of ethylene glycol (50 parts by mass with respect to 100 parts by mass of phenol) were mixed. went. Subsequently, the two-phase mixture (white cloudy state) formed by stirring and mixing was gradually heated to the reflux temperature, and further subjected to a condensation reaction at the same temperature for 10 hours. After the reaction was stopped, methyl isobutyl ketone was added to the reaction mixture with stirring and mixing to dissolve the condensation product. Thereafter, stirring and mixing were stopped, and the contents were transferred to a separation flask and allowed to stand, and separated into a methyl isobutyl ketone solution layer (upper layer) and a phosphoric acid aqueous solution layer (lower layer). Next, the phosphoric acid aqueous solution layer was removed, and the methyl isobutyl ketone solution was washed with water several times to remove phosphoric acid, and then the contents were returned to the reaction vessel again, and methyl isobutyl ketone was completely removed by distillation under reduced pressure. Obtained 5 parts by mass of a novolac type phenolic resin. This novolak type phenol resin had a number average molecular weight (Mn) of 755, a weight average molecular weight (Mw) of 1227, and a dispersion ratio (Mw / Mn) of 1.63. The above Mn and Mw were measured by gel filtration chromatograph (“SC-8020 series build-up system” manufactured by Tosoh Corporation, column: G2000Hxl + G4000Hxl, detector: UV254 nm, carrier: tetrahydrofuran 1 mL / min, column temperature: 38 ° C.). And calculated in terms of standard polystyrene. The dispersion ratio (Mw / Mn) was calculated from the obtained Mn and Mw. Moreover, in the measurement by the said gel filtration chromatograph, when the area occupation rate of the phenolic monomer and the phenolic dimer with respect to the whole area of molecular weight distribution was measured, they were 0.3% and 3.3%, respectively.

Next, 100 parts by mass of the above-mentioned novolak type phenolic resin, 100 parts by mass of graphite (graphite) (Nippon Graphite Industries Co., Ltd.), 5 parts by mass of boric acid (Nippon Denko Co., Ltd.), and carbon fiber ("Toray Industries" TA008A ") 32 parts by mass, 15 parts by mass of hexamethylenetetramine as a curing agent and 3 parts by mass of calcium stearate as a release agent were blended and mixed uniformly. Thereafter, 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 granular resin composition.

The obtained resin composition was compression-molded at a molding temperature of 180 ° C. and a molding pressure of 15 t using a 20-ton press, and then pulverized with a cutter mill and a pin mill, and a pulverized product (resin having a maximum particle size of 0.04 mm or less) Powder A) was obtained. The maximum particle size after pulverization was measured using a laser scattering diffraction particle size distribution analyzer.

[Method for producing resin composition for sliding member]
<Example 1>
After 100 parts by weight of PPS (“A900” manufactured by Toray Industries, Inc.), 0.2 parts by weight of boric acid (Nippon Denko) and 25 parts by weight of graphite (Nippon Graphite Industries) are mixed uniformly with a mixer, biaxial extrusion The mixture was melt-kneaded at a screw rotation speed of 6 to 16 rpm and an extrusion tip temperature of 265 to 295 ° C. to obtain pellets. The pellets were dried in a dryer at 130 ° C. for 4 hours, and then a test piece for evaluation was molded at a cylinder temperature of 280 ° C. to 320 ° C. and a mold temperature of 150 ° C. using an injection molding machine.

<Example 2>
A test piece was prepared in the same manner as in Example 1 except that boric acid was used in an amount of 1.5 parts by mass.

<Example 3>
A test piece was prepared in the same manner as in Example 1 except that 3 parts by mass of boric acid was used.

<Example 4>
A test piece was prepared in the same manner as in Example 1 except that 5 parts by mass of boric acid was used.

<Example 5>
A test piece was prepared in the same manner as in Example 1 except that 100 parts by mass of PPS (“A900” manufactured by Toray Industries Inc.) and 10.2 parts by mass of the resin powder A obtained by the above-described method were uniformly mixed by a mixer. .

<Example 6>
A test piece was prepared in the same manner as in Example 5 except that 25.5 parts by mass of the resin powder having the composition shown in Table 1 was used instead of the resin powder A. In addition, the used resin powder was manufactured by the same method as the case of the said resin powder A except having mix | blended the raw material with the composition shown in Table 1. The same applies to Examples 7 to 9, 15 and 17 described later.

<Example 7>
A test piece was prepared in the same manner as in Example 5 except that 76.5 parts by mass of the resin powder having the composition shown in Table 1 was used instead of the resin powder A.

<Example 8>
A test piece was prepared in the same manner as in Example 5 except that 153 parts by mass of the resin powder having the composition shown in Table 1 was used instead of the resin powder A.

<Example 9>
A test piece was prepared in the same manner as in Example 5 except that 255 parts by mass of the resin powder having the composition shown in Table 1 was used instead of the resin powder A.

<Example 10>
100 parts by mass of PPS (“A900” manufactured by Toray Industries, Inc.), 1.5 parts by mass of boric acid (Nippon Denko), 25 parts by mass of graphite (Nippon Graphite Industries Co., Ltd.), and 25 parts by mass of a cured novolac type phenolic resin A test piece was prepared in the same manner as in Example 1 except that the mixture was uniformly mixed. In addition, as said novolak-type phenol resin hardened | cured material, after mixing 100 mass parts of novolak-type phenol resins ("CP1006" of Asahi Organic Materials Co., Ltd.) and 12 mass parts of hexamethylenetetramine, it heat-hardened, and then grind | pulverized. A thing was used.

<Example 11>
A test piece was prepared in the same manner as in Example 1 except that the boron compound was changed to 1.5 parts by mass of zinc borate instead of boric acid.

<Example 12>
A test piece was prepared in the same manner as in Example 1 except that the boron compound was changed to 1.5 parts by mass of boron oxide instead of boric acid.

<Example 13>
A test piece was prepared in the same manner as in Example 1 except that the boron compound was changed to 1.5 parts by mass of borax instead of boric acid.

<Example 14>
After 100 parts by weight of PA (“CM-3001N” manufactured by Toray Industries, Inc.), 1.5 parts by weight of boric acid (Nippon Denko) and 25 parts by weight of graphite (Nippon Graphite Industries) were mixed uniformly with a mixer, Pellets were obtained by melt-kneading with a shaft extruder at a screw speed of 200 rpm and an extrusion tip temperature of 250 to 280 ° C. The obtained pellets were dried in a dryer at 80 ° C. for 12 hours, and then a test piece for evaluation was molded using an injection molding machine under conditions of a cylinder temperature of 260 to 280 ° C. and a mold temperature of 85 ° C.

<Example 15>
A test piece was prepared in the same manner as in Example 1 except that 100 parts by mass of PA (“CM-3001N” manufactured by Toray Industries, Inc.) and 25.5 parts by mass of resin powder having the composition shown in Table 1 were uniformly mixed by a mixer. did.

<Example 16>
After 100 parts by weight of PEEK ("VESTAKEEEP 2000G" manufactured by Daicel Eponic Corporation), 1.5 parts by weight of boric acid (Nippon Denko) and 25 parts by weight of graphite (Nippon Graphite Industries Co., Ltd.) were uniformly mixed by a mixer, Pellets were obtained by melt-kneading with a twin-screw extruder at a screw speed of 200 rpm and an extrusion tip temperature of 310 to 360 ° C. The obtained pellets were dried in a dryer at 150 ° C. for 5 hours, and then a test piece for evaluation was molded using an injection molding machine under conditions of a cylinder temperature of 360 to 380 ° C. and a mold temperature of 180 ° C.

<Example 17>
A test piece was prepared in the same manner as in Example 1 except that 100 parts by mass of PEEK ("VESTAKEEEP 2000G" manufactured by Daicel Eponic Corporation) and 25.5 parts by mass of resin powder having the composition shown in Table 1 were uniformly mixed by a mixer. Produced.

<Comparative Example 1>
A test piece was prepared in the same manner as in Example 1 except that 100 parts by mass of PPS (“A900” manufactured by Toray Industries, Inc.) was uniformly mixed with a mixer.

<Comparative example 2>
A test piece was prepared in the same manner as in Example 1 except that 100 parts by mass of PPS (“A900” manufactured by Toray Industries, Inc.) and 25 parts by mass of graphite (Nippon Graphite Industries Co., Ltd.) were uniformly mixed by a mixer.

<Comparative Example 3>
A test piece was prepared in the same manner as in Example 1 except that 100 parts by mass of PPS (“A900” manufactured by Toray Industries, Inc.) and 1.5 parts by mass of boric acid were uniformly mixed by a mixer.

<Comparative example 4>
A test piece was produced in the same manner as in Example 1 except that 100 parts by mass of PA (“CM-3001N” manufactured by Toray Industries, Inc.) was uniformly mixed with a mixer.

<Comparative Example 5>
A test piece was prepared in the same manner as in Example 1 except that 100 parts by mass of PA (“CM-3001N” manufactured by Toray Industries Inc.) and 25 parts by mass of graphite (Nippon Graphite Industries Co., Ltd.) were uniformly mixed with a mixer.

<Comparative Example 6>
A test piece was prepared in the same manner as in Example 1 except that 100 parts by mass of PA (“CM-3001N” manufactured by Toray Industries, Inc.) and 1.5 parts by mass of boric acid were uniformly mixed with a mixer.

<Sliding characteristics test method>
(1) Friction and wear test evaluation (resin wear, dynamic friction coefficient, rising temperature)
These evaluation items were measured using a friction and wear tester ("AFT-6-A" from Orientec) under the following conditions. In addition, since the specific gravity of each Example changed with mixing | blending about the resin abrasion amount, it evaluated by the volume worn. The results are shown in Tables 1 and 2. In addition, it is desirable that the resin wear amount, the dynamic friction coefficient, and the rising temperature have lower numerical values.

Shape of test piece: Square plate test piece of 30 mm × 30 mm × Thickness of 3 mm Shape of mating material: hollow cylinder with outer diameter of 25.6 mm, inner diameter of 20 mm, and length of 15 mm Material of mating material: S45C
Test surface pressure: 0.49 MPa (PPS, PA), 0.98 MPa (PEEK)
Test speed: 0.33 m / s (rotation speed 250 rpm)
Environment: Unlubricated Sliding distance: 1188m
Test time: 60min

(2) PV value In the test of (1) above, the test speed was changed from 0.33 m / s (rotation speed: 250 rpm) to 2.99 MPa under a constant surface pressure of 0.49 MPa for PPS and PA and 0.98 MPa for PEEK. The acceleration was carried out stepwise by 0.33 m / s every 20 minutes up to 68 m / s (rotation speed 2000 rpm). At this time, the product of the test surface pressure and the test speed under the limit sliding test condition where the frictional resistance is increased and the sliding test is impossible is defined as the PV value. The results are shown in Tables 1 and 2. A higher PV value is desirable.

<Examination of evaluation results>
As is clear from Tables 1 and 2, it can be seen that the test pieces of Examples 1 to 17 have an improved frictional wear test evaluation than the test pieces of Comparative Examples 1 to 6. This is presumably because the sliding member resin compositions of Examples 1 to 17 contain a boron compound and graphite. In addition, the test piece of Comparative Example 2 is improved in the frictional wear test evaluation by adding graphite as compared with the test pieces of Comparative Examples 1 and 3, but the test pieces of Examples 1 to 17 are Comparative Example 2. The friction and wear test evaluation is improved as compared with the test piece. This is considered to be that the frictional wear test evaluation is improved by further containing a boron compound in addition to graphite and by the synergistic effect of the graphite and the boron compound as compared with the case of adding only graphite. In addition, the content of the boron compound in the test pieces of Examples 1 to 17 is 0.2 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the thermoplastic resin. It is considered that the friction and wear test evaluation is further improved by being in the above range.

In particular, the test piece of Example 7 has an improved frictional wear test evaluation than the test piece of Example 10. This is presumably because boric acid and graphite contained in the resin composition for sliding members of Example 7 were added as resin powders containing them.

According to the present invention, sliding characteristics such as wear resistance can be improved by containing graphite and a boron compound. Thereby, the temperature rise by the friction in the sliding member formed from the said resin composition for sliding members is suppressed.

Claims (10)

A resin composition for a sliding member containing a thermoplastic resin, graphite, and a boron compound. The resin composition for a sliding member according to claim 1, wherein the thermoplastic resin is polyphenylene sulfide, polyamide, polyether ether ketone, or a combination thereof. 3. The resin composition for a sliding member according to claim 2, wherein the thermoplastic resin is polyether ether ketone. 4. The resin composition for a sliding member according to claim 1, wherein a content of the boron compound is 0.2 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the thermoplastic resin. . The whole or part of at least one of the boron compound and the graphite is contained as a resin powder containing at least one of the boron compound and graphite and a phenol resin. The resin composition for sliding members according to any one of the above. The resin composition for a sliding member according to claim 5, wherein the maximum particle size of the resin powder is 0.04 mm or less. The resin composition for a sliding member according to claim 5 or 6, wherein the resin powder is formed from a sprue, a runner, a molding failure product, or a used molding product generated during molding. The resin composition for a sliding member according to any one of claims 1 to 7, wherein the boron compound is boric acid, zinc borate, boron oxide, or a combination thereof. The resin composition for a sliding member according to claim 8, wherein the boron-based compound is boric acid. A sliding member comprising the resin composition for a sliding member according to any one of claims 1 to 9.