JP7165298B2 - Composite material for sliding and sliding member provided with the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a sliding composite material and a sliding member having the same.

As this type of composite material, for example, a laminate obtained by impregnating a fiber base material with various resins to form a prepreg, laminating and curing the prepreg is known. Of these, laminates made by impregnating phenolic resin into fabrics such as cotton cloth are excellent in flame retardancy, friction and wear properties during lubrication, and mechanical strength, and can be manufactured at a relatively low cost. Widely used as other sliding members. However, in the case of a composite material in which, for example, cotton cloth is impregnated with phenolic resin, since the cotton cloth and phenolic resin have good affinity for water, the water absorption rate is high and the material swells, resulting in large dimensional change. Therefore, it has been considered unsuitable for applications where high dimensional accuracy is required, such as when used under wet conditions.

As a measure to improve this, it has been proposed to use a fabric using fibers with low water absorption as a base material (see, for example, Patent Documents 1 to 3).

In Patent Document 1, at least two single-twisted yarns of a fluororesin fiber and a single-twisted yarn of a polyphenylene sulfide (PPS) fiber are aligned, and a two-ply yarn formed by twisting the single-twisted yarn in the direction opposite to the single-twisted direction is used as a warp. And a sliding surface material in which a reinforcing base material made of a woven fabric formed as wefts is impregnated with a resol-type phenolic resin in which ethylene tetrafluoride (PTFE) resin is dispersed, wherein the reinforcing base material is a plain woven fabric, It is described that the density of this plain weave fabric is 36 to 44 warps/2.54 cm and 36 to 44 wefts/2.54 cm. It is said that by having such a structure, it is possible to obtain a sliding surface material that has good adhesion between the base material and the phenolic resin, excellent friction and wear properties, low water swelling, and high dimensional accuracy. .

In Patent Document 2, phenols containing 50 to 100 mol% of bisphenol A and formaldehydes are synthesized using amines as a catalyst, and the number average molecular weight Mn measured by gel permeation chromatography is 500 to 1000, and the weight A fiber for a sliding member obtained by impregnating a polyphenylene sulfide (PPS) fiber fabric with a resol-type phenolic resin having a dispersity Mw/Mn as a ratio of the average molecular weight Mw to the number average molecular weight Mn of 2.5 to 15. A reinforced resin composition is described. It is said that this results in good adhesion between the PPS fiber woven fabric and the phenolic resin, and good swelling resistance against water.

Patent Document 3 discloses a multi-layer fabric containing a sliding fabric and a base fabric that may be impregnated with a resin, wherein the sliding fabric is a fabric containing polytetrafluoroethylene fiber A, and the base fabric is A woven fabric made of fiber B whose creep rate is lower than that of polytetrafluoroethylene fiber under a load of 20% of the breaking strength in a standard state, and polytetrafluoroethylene fiber A contains tetrafluoroethylene in 90 mol% or more of the whole. A wear-resistant multi-layer fabric is described which consists of a copolymer, in which the fibers B are polyphenylene sulfide fibers, and in which the sliding fabric and the base fabric are intertwined and bonded with their warp and/or weft threads. As a result, it is said that the wear resistance is high and that the slidability can be exhibited for a long period of time even in an environment under a higher load than before.

Japanese Patent No. 5859183 Japanese Patent No. 5249726 Japanese Patent No. 5988006

According to the inventions described in the above-mentioned patent documents, it is possible to some extent to obtain a composite material in which swelling of water is suppressed while the adhesiveness between the base material and the impregnating resin is adequately secured. However, in the invention described in Cited Document 1, it is necessary to use a specific woven fabric formed from specific yarns using fluororesin fibers and PPS fibers, and to impregnate the base material with PTFE resin. , mechanical strength, and cost. In the invention described in Cited Document 2, since the PPS fiber woven fabric is used, it is difficult to impregnate the phenolic resin, and there is room for improvement in terms of abrasion resistance and cost. In the invention described in Cited Document 3, it is necessary to use a multi-layer fabric containing a sliding fabric of PTFE fibers and a base fabric of PPS fibers that may be impregnated with resin, which improves mechanical strength and cost. There is room for

Accordingly, an object of the present invention is to achieve good mechanical strength for sliding applications without impairing the properties of phenolic resins, while the base material and the impregnated resin are well integrated, water swelling is suppressed, and the properties of phenolic resins are not compromised. To provide a sliding composite material and a sliding member having the same at a low cost.

As a result of intensive studies by the present inventors, the use of a PPS fiber nonwoven fabric as a base material allows the phenol resin to penetrate satisfactorily without being restricted by the fiber bundles of the PPS fiber, and suppresses swelling of water. The inventors have found that it is possible to inexpensively provide a sliding composite material having good mechanical strength for sliding applications and a sliding member comprising the same without impairing the properties of the phenolic resin. The gist of the present invention is as follows.

A first aspect of the present invention is a sliding composite material comprising a base material and a phenolic resin, wherein the base material is a nonwoven fabric made of polyphenylene sulfide fibers, the nonwoven fabric is impregnated with the phenolic resin , and the base material is It relates to a sliding composite material in which the ratio (A/B) of (A) and the phenolic resin (B) is 30/70 to 55/45 on a weight basis .

In embodiments of the present invention, the phenolic resin may be a novolac phenolic resin. Also, the substrate may have a reinforcing layer. Also, the nonwoven fabric may have a basis weight of 250 to 650 g/m ² . Moreover, the nonwoven fabric may be impregnated with at least one selected from molybdenum disulfide, graphite, carbon black and carbon fiber. Moreover, the substrate may be provided with a plurality of nonwoven fabrics, and in this case, the nonwoven fabrics may be laminated in the thickness direction.

A second aspect of the present invention relates to a sliding member having a sliding surface provided with the sliding composite material described above.

According to the present invention, the base material and the impregnated resin are well integrated, water swelling is suppressed, and good mechanical strength for sliding applications is achieved without impairing the properties of the phenolic resin. It is possible to inexpensively provide a sliding composite material having such a material and a sliding member having the same.

FIG. 2 is a graph showing changes over time in the wear height of each test piece when a pin-on-disk test was performed using the test pieces of Examples 1 and 2 and Comparative Examples 1 and 2. FIG.

Embodiments of the present invention will be described below.

An embodiment of the composite sliding material according to the present invention comprises a substrate and a phenolic resin. The substrate is a non-woven fabric of polyphenylene sulfide (PPS) fibers. Also, this nonwoven fabric is impregnated with a phenolic resin.

The PPS fibers are excellent in heat resistance, chemical resistance and hydrolysis resistance. Moreover, the water absorption of the PPS fiber is set to 0.1% by weight or less. Therefore, swelling of the composite material by water can be suppressed by using PPS fibers. In addition, PPS itself is said to have impact resistance and mechanical strength comparable to those of general-purpose engineering plastics, and PPS fibers may similarly have excellent mechanical strength. A PPS fiber having such properties is a synthetic fiber composed of a polymer having --(C ₆ H ₄ --S)-- as its main structural unit. A structural unit represented by —(C ₆ H ₄ —S)— may be a p-phenylene unit or an m-phenylene unit. Other structural units include -(C ₆ H ₄ -O-C ₆ H ₄ -S)-, -(C ₆ H ₄ -SO ₂ -C ₆ H ₄ -S)-, -( C ₆ H ₄ -CO-C ₆ H ₄ -S)-, -(C ₆ H ₃ (CH ₃ )-S)-, -(C ₆ H ₂ (CH ₃ ) ₂ -S)-, etc. . Further, the polymer having the structural unit —(C ₆ H ₄ —S)— as a structural unit preferably has a linear structure, but may partially have a crosslinked structure. Representative examples of these PPS polymers include polyphenylene sulfide, polyphenylene sulfide sulfone, polyphenylene sulfide ketone, random copolymers, block copolymers and mixtures thereof. Preferred PPS polymers contain p-phenylene units represented by —(C ₆ H ₄ —S)— in an amount of preferably 70 mol % or more, more preferably 90 mol % or more, as the main structural unit of the polymer. It is.

The fiber length of the PPS fibers is preferably 2 to 100 mm from the viewpoint of obtaining better strength of the nonwoven fabric. From the same point of view, the fineness of the single fiber is preferably 0.1 to 15 denier.

Examples of commercially available PPS fibers include Torcon (registered trademark) manufactured by Toray Industries, Inc. and Procon (registered trademark) manufactured by Toyobo Co., Ltd.

The nonwoven fabric that constitutes the base material can be, for example, one specified in JIS L0222. For example, in a web obtained by laminating fibers and spreading them in a sheet form, the fibers are moderately bonded by the following (a) to (e) to form a cloth. (b) fusing by heating; (c) mechanical entangling with hooked needles (needle punch); (d) entangling by jetting high-pressure water jets; and (e) web stitching (stitch bond). Among these, needle-punched nonwoven fabrics are preferred from the viewpoint of better integration with the phenol resin. A nonwoven fabric produced by needle punching has a so-called felt-like appearance. In the case of needle-punched nonwoven fabrics, it is easier to impregnate with phenolic resin than other nonwoven fabrics and fabrics, and the fibers are entangled with pinpoints, so the contact area between the PPS fibers and the phenolic resin is said to be large. Conceivable. As a result, it is considered that a dense structure with few voids can be obtained, and better properties can be obtained.

The basis weight of the nonwoven fabric is preferably 250 to 650 g/m ² from the viewpoint of obtaining better strength of the nonwoven fabric and achieving better integration with the phenolic resin. If the basis weight is lowered within this range, the impregnation amount of the phenolic resin relatively increases, and the strength tends to increase. Increasing the basis weight within this range tends to increase the abrasion resistance. Therefore, in applications where wear resistance is more important, the basis weight can be set to, for example, 450 to 650 g/m ² . Moreover, the tensile strength of the nonwoven fabric is preferably 15 N/mm ² or more for the reason that the sealing material for sliding can be produced more stably and at a lower cost. Further, the upper limit of the tensile strength is not particularly limited as long as it is within such a range. It can be appropriately set according to the configuration of the nonwoven fabric of PPS fibers or the nonwoven fabric combined with a reinforcing layer to be described later. The upper limit of the nonwoven fabric of PPS fibers can be, for example, 50 N/mm ² or less because it is generally readily available at low cost. The nonwoven fabric preferably has a thickness of less than 3 mm and a weight per unit area of 650 g/m ² or less for the reason that a prepreg in which the phenolic resin or the like is evenly dispersed can be obtained by the impregnation operation.

Phenolic resins are generally excellent in heat resistance and flame retardancy, and have good mechanical properties. Therefore, by impregnating the above-described PPS fiber base material with a phenol resin and forming a composite, a composite material having excellent flame retardancy and mechanical strength and suppressing water absorption can be obtained. Phenolic resins may be reaction products of phenols and aldehydes, and known ones can be employed.

Phenols are not particularly limited, and include alkylphenols (cresol, xylenol, etc.), polyhydric phenols (resorcinol, etc.), phenylphenol, aminophenol and the like. Aldehydes are not particularly limited, and formaldehyde, paraformaldehyde, acetaldehyde, furfural and the like can be mentioned.

As the phenolic resin for impregnating the nonwoven fabric, either a resol-type phenolic resin or a novolac-type phenolic resin may be used, and the resin can be appropriately selected according to the application. A novolak-type phenolic resin is preferred from the viewpoint of better integration with the nonwoven fabric of PPS fibers. A resol-type phenolic resin is obtained, for example, by reacting phenols and aldehydes in excess of aldehydes under a base catalyst. A novolak-type phenolic resin is obtained, for example, by reacting phenols and aldehydes in the presence of excess phenols and an acid catalyst. Commercially available products can be used as such resol-type phenolic resins and novolac-type phenolic resins. For example, SUMILITE RESIN (registered trademark) PR series manufactured by Sumitomo Bakelite Co., Ltd. may be used.

By curing a resol-type phenolic resin and a novolac-type phenolic resin, a member for the sliding surface of a sliding member can be obtained. Resol-type phenolic resins can be cured by heating or addition of acid. A novolak-type phenolic resin can be cured by heating in the presence of a cross-linking agent. Examples of the cross-linking agent for curing the novolak-type phenol resin include hexamethylenetetramine. Moreover, the conditions for curing can be appropriately selected according to the types of the resol-type phenolic resin and the novolak-type phenolic resin.

The nonwoven fabric may be impregnated with other additives besides the phenolic resin. Examples of such additives include lubricants, damping agents, reinforcing agents, heat-resistant agents, flame retardants, and weather-resistant agents.

Lubricants include, for example, graphite, molybdenum disulfide, carbon black, carbon fiber, hexagonal boron nitride, and talc.

Examples of damping agents include graphite, carbon fiber, potassium titanate, and mica.

Examples of reinforcing agents include carbon fiber, wollastonite, potassium titanate, xonotlite, aramid fiber, glass fiber, talc, and mica.

Examples of heat-resistant agents include heat insulating agents such as glass balloons, silica balloons and shirasu balloons; thermal conductivity imparting agents such as alumina, aluminum nitride and boron nitride; agents and the like.

Examples of flame retardants include hydroxide-based flame retardants such as aluminum hydroxide and magnesium hydroxide, halogen-based flame retardants, phosphorus-based flame retardants, antimony-based flame retardants, zinc borate, red phosphorus, zinc carbonate, and hydrotalcite. , dawsonite and the like.

Weather resistant agents include, for example, titanium oxide and zinc oxide.

Among the above additives, at least one selected from molybdenum disulfide, graphite, carbon black, and carbon fiber from the viewpoint of exhibiting the function while suppressing the aggressiveness of the sliding member to the mating material. is preferred.

The substrate may have a reinforcing layer. Examples of such a reinforcing layer include cloth such as a scrim cloth provided between nonwoven fabrics of PPS fibers, a filter cloth (filter cloth), and the like. Such fabrics are preferably formed of PPS fibers, for example. The reinforcing layer can be provided, for example, in the inner layer of the nonwoven fabric or adjacent to at least one side. When forming a laminate in which prepregs are laminated, the reinforcing layer may be provided on all nonwoven fabrics, or may be provided on some of the nonwoven fabrics, depending on the application. The reinforcing layer can be integrated with the nonwoven, for example, when forming the nonwoven.

The number of nonwoven fabrics in the substrate can be appropriately determined depending on the application, and may be one or more. Moreover, when the thickness of the composite material for sliding is to be increased, it is preferable that a plurality of nonwoven fabrics are laminated in the thickness direction of the substrate.

The ratio (A/B) of the base material (A) and the phenolic resin (B) is not particularly limited, and is, for example, 30/70 to 55/45 on a weight basis. In addition, the content of the additives described above is not particularly limited, and can be appropriately determined according to the type thereof. For example, the amount of lubricant added can be more than 0 parts by weight and 20 parts by weight or less with respect to 100 parts by weight of the phenolic resin. Further, for example, the reinforcing agent, heat-resistant agent, flame retardant, and weather resistance imparting agent can be used in an amount of more than 0 parts by weight and 6 parts by weight or less with respect to 100 parts by weight of the phenolic resin. When using a plurality of additives, the upper limit can generally be 50 parts by weight or less with respect to 100 parts by weight of the phenolic resin. The amount is preferably 30 parts by weight or less, more preferably 25 parts by weight or less based on 100 parts by weight of the phenolic resin, because it is easy to uniformly disperse it in the phenolic resin of the composite material for sliding.

A sliding composite material can be manufactured by a known method. For example, a nonwoven fabric of PPS fibers is first brought into contact with a varnish containing a phenolic resin. Examples of the method of contacting the PPS fiber nonwoven fabric with the varnish containing the phenolic resin include a method of immersing the PPS fiber nonwoven fabric in the varnish, a method of applying the varnish, and a method of spraying the varnish. At this time, the nonwoven fabric may be brought into contact with the varnish one by one, or may be brought into contact with the varnish continuously while moving the long nonwoven fabric in the longitudinal direction using a device such as an uncoiler. good too. Considering mass productivity, it is preferable to bring the long nonwoven fabric into continuous contact with the varnish. In this case, if the tensile strength of the nonwoven fabric is equal to or higher than the above lower limit, more stable treatment can be performed. Then, the nonwoven fabric is impregnated with the varnish by applying surface pressure with, for example, gap rolls. At the same time, remove excess varnish if necessary. Thereafter, the nonwoven fabric impregnated with the varnish is heated to remove the solvent contained in the varnish and partially cure the phenolic resin. As a result, a nonwoven fabric prepreg impregnated with a phenolic resin is formed. This prepreg is an embodiment of the sliding composite material of the present invention.

When the varnish is a resol-type phenolic resin, the varnish contains a resol-type phenolic resin, an acid added as necessary, an additive added as necessary, and a solvent. In the case of a novolac-type phenolic resin, it contains a novolak-type phenolic resin, a cross-linking agent, additives added as necessary, and a solvent. A conventionally known solvent can be used.

By heating and pressurizing the prepreg to further harden the phenolic resin, a sliding surface member constituting the sliding surface of the sliding member is obtained. When forming a sliding surface member in which a plurality of nonwoven fabrics are laminated, a laminate in which a plurality of nonwoven fabrics are integrated can be obtained by laminating the nonwoven fabrics in the thickness direction and applying heat and pressure. Such a sliding surface member is also an embodiment of the sliding composite material of the present invention.

Using the prepreg, a sliding surface member having a predetermined shape can be molded by a known method. For example, in the case of a flat plate, it can be obtained by arranging a prepreg in a flat plate and applying heat and pressure. In the case of a cylindrical shape, it can be obtained by applying heat and pressure while winding the prepreg around a core mold having a desired outer diameter. Further, when forming a desired outer surface shape, it is obtained by laying small pieces of prepreg on the surface of a mold having a surface shape corresponding to this outer surface shape and applying heat and pressure. Also, after the prepreg is heated and pressurized, it can be cut into a desired shape.

Thus, the composite material obtained by heating and pressing the prepreg can be used as a sliding surface member provided on the sliding surface of the sliding member. Sliding members include, for example, scratch-proof members that require sliding on steel lines, bearings and liners for ships and marine applications and various devices. Among these, since dimensional change can be suppressed even when in contact with water, it is particularly suitable as a bearing for water lubrication used in ships, water supply and drainage pumps, and the like. In addition, since it is possible to use general phenolic resin and PPS fiber nonwoven fabric, it is possible to provide a sliding composite material and a sliding member at low cost. In addition, the phenol resin is simply impregnated into the nonwoven fabric of PPS fibers, and since the PPS fibers are excellent in heat resistance, the flame retardant properties of the phenol resin are not impaired, and good mechanical strength is obtained.

Hereinafter, embodiments of the present invention will be described in more detail based on examples.

(Example 1)
A varnish was prepared with 46% by weight of a novolak phenolic resin (SUMILITE RESIN (registered trademark) PR-50252 manufactured by Sumitomo Bakelite Co., Ltd.), 4% by weight of a cross-linking agent hexamine, and 50% by weight of a solvent (methanol). After immersing a PPS fiber nonwoven fabric (Torcon (registered trademark) RF55, needle-punched nonwoven fabric, basis weight : 550 g/m ² , thickness: 1.4 mm, tensile strength: 40 N/mm ² , manufactured by Toray Industries, Inc.) in varnish, the nonwoven fabric was was passed between squeeze rolls to impregnate the nonwoven fabric with the varnish. Then, it was dried at 100° C. for 60 minutes to obtain a prepreg. The prepreg had a weight ratio of PPS fiber nonwoven fabric and phenolic resin of 45/55.

After laminating 22 layers of prepreg in the thickness direction, they were heated and pressed at 180° C. and 5 MPa for 60 minutes to obtain a sliding surface member.

(Example 2)
As the non-woven fabric of PPS fibers, instead of Torcon (registered trademark) RF55 manufactured by Toray Industries, Inc., RFSL30 manufactured by Fujiko Co., Ltd., basis weight : 300 g/m ² , thickness: 0.5 mm, tensile strength: 20 N/mm ² is used. A prepreg and a sliding surface member were obtained in the same manner as in Example 1, except that the prepreg was used.

(Comparative example 1)
Instead of the non-woven fabric of PPS fibers, a plain weave of PPS fibers (manufactured by Toray Industries, Inc., TFRC-1, basis weight : 380 g/m ² , thickness: 0.6 mm, tensile strength: 15 N/mm ² ) was used. A prepreg and a sliding surface member were obtained in the same manner as in Example 1.

(Comparative example 2)
Example 1 except that a cotton cloth (manufactured by Tokokosen Co., Ltd., No. 11 canvas, basis weight : 340 g/m ² , thickness: 0.6 mm, tensile strength: 30 N/mm ² ) was used instead of the nonwoven fabric of PPS fibers. A prepreg and a sliding surface member were obtained in the same manner.

Test pieces were produced from the sliding surface members obtained in Examples 1 and 2 and Comparative Examples 1 and 2, and the following evaluation tests were performed. Table 1 shows the evaluation results. Fig. 1 shows changes in wear height over time.

(evaluation)
<Specific gravity>
The specific gravity was measured by a method based on JIS K7112.

<Hardness>
Rockwell hardness was measured in the thickness direction of the sliding surface member by a method based on JIS K7202.

<Bending properties>
A bending test was performed in the thickness direction of the sliding surface member by a method conforming to JIS K6911.

<Compression characteristics>
A compression test was performed in the thickness direction of the sliding surface member by a method conforming to JIS K6911.

<Dimensional stability>
A dimensional change in the thickness direction of the slide surface member was calculated after a test piece of 50 mm×50 mm×10 mm in thickness was allowed to stand in water maintained at 20° C. for 28 days.

<Friction and wear characteristics>
A test piece of φ5 mm was prepared, and a pin-on-disk test was performed under the conditions shown in Table 2 using a pin-on-disk type friction and wear tester (manufactured by Starlite Industry Co., Ltd., Auto Pin Disk APD-101). . Two tests were performed. The φ5 mm test piece was arranged such that the central axis direction was aligned with the thickness direction of the sliding surface member. In Table 1, the specific wear amount means the calculated wear height per hour when the elapsed time from the start of the test is 30 to 40 hours. The test results are shown in Table 1 and FIG.

As shown in Table 1, by using the PPS fiber nonwoven fabric, in Examples 1 and 2, the hardness, bending strength, and compressive strength are equal to or higher than those in Comparative Examples 1 and 2, and water absorption is suppressed. As a result, the dimensional change rate is extremely low. Moreover, it turns out that a specific wear amount can also be reduced significantly. As shown in FIG. 1, it can be seen that the wear height of Examples 1 and 2 is significantly lower than that of Comparative Examples 1 and 2 throughout the test time.

Claims (7)

A sliding composite material comprising a base material and a phenolic resin,
The base material is a nonwoven fabric of polyphenylene sulfide fibers, and the nonwoven fabric is impregnated with the phenol resin ,
A sliding composite material , wherein the ratio (A/B) of the substrate (A) and the phenolic resin (B) is 30/70 to 55/45 on a weight basis . 2. A sliding composite material according to claim 1, wherein said phenolic resin is a novolac type phenolic resin. The composite sliding material according to claim 1 or 2, wherein the base material has a reinforcing layer. The composite sliding material according to any one of claims 1 to 3, wherein the nonwoven fabric has a basis weight of 250 to 650 g/ ^m2 . The composite sliding material according to any one of claims 1 to 4, wherein the nonwoven fabric is impregnated with at least one selected from molybdenum disulfide, graphite, carbon black and carbon fiber. The sliding composite material according to any one of claims 1 to 5, wherein the substrate comprises a plurality of nonwoven fabrics, and the nonwoven fabrics are laminated in the thickness direction. A sliding member having a sliding surface provided with the sliding composite material according to any one of claims 1 to 6.

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