JP5897961B2 - Plain bearing - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a sliding bearing used for engines of automobiles and other industrial machines, and in particular, a solid lubricant on a bearing base material having a back metal and a bearing alloy layer disposed on the back metal. The present invention relates to a plain bearing provided with a resin coating layer containing.

  In recent years, the performance of automobile engines with high output and high rotation has been remarkably improved, and excellent sliding performance such as initial conformability, seizure resistance, durability, and heat resistance is desired for sliding bearing materials.

  Sliding bearings are required to have both wear resistance and compatibility with the other sliding member, but the characteristics are contradictory. In general, it is known that fatigue resistance and seizure resistance can be secured by providing a bearing alloy layer (lining layer) of aluminum or copper on the back metal of a slide bearing, but the initial conformability is insufficient. There is a case. Therefore, in order to ensure conformability, a coating layer called an overlay, such as a soft metal coating such as Sn or Pb, or a resin coating layer containing a solid lubricant, is further provided on the bearing alloy layer. (Patent Document 1).

JP-A-7-247493

The resin layer in which the solid lubricant is held by the resin has better wear resistance characteristics than the soft metal coating, but has low heat resistance and room for improvement such as seizure during initial sliding.
Therefore, an object of the present invention is to provide a plain bearing that improves the heat resistance of a resin coating layer in which a solid lubricant is held by a resin and is excellent in seizure resistance.

  As a result of earnest study to achieve the above object, the present inventor has achieved the above object by adding a wax and an antioxidant to the resin coating layer.

That is, the present invention relates to the following <1> to <7>.
<1> A sliding bearing having a resin coating layer on a sliding bearing base material having a backing metal and a bearing alloy layer provided on the backing steel,
The resin coating layer is a plain bearing including a binder resin, a solid lubricant, a wax, and an antioxidant.
<2> The plain bearing according to <1>, wherein the resin coating layer has a thickness of 3 to 20 μm.
<3> The plain bearing according to the above <1> or <2>, wherein the solid lubricant contains one or more selected from the group consisting of molybdenum disulfide, graphite, and fluorine compounds.
<4> The plain bearing according to any one of <1> to <3>, wherein the wax content in the resin coating layer is 0.1 to 15 parts by weight with respect to 100 parts by weight of the binder resin.
<5> The plain bearing according to any one of <1> to <4>, wherein the antioxidant content in the resin coating layer is 0.1 to 10 parts by weight with respect to 100 parts by weight of the binder resin.
<6> The above-mentioned <1> to <5>, wherein the resin coating layer has a two-layer structure, the upper resin coating layer contains the wax and the antioxidant, and the lower resin coating layer contains no wax. Or a plain bearing according to claim 1.
<7> The plain bearing according to <6>, wherein the lower resin coating layer has a thickness of 0.1 μm or more.

  According to the present invention, the resin coating layer in which the solid lubricant is held by the binder resin contains the wax and the antioxidant, thereby reducing the sliding resistance of the sliding surface and imparting excellent seizure resistance. A plain bearing can be provided.

Hereinafter, the present invention will be described in detail.
The sliding bearing according to the present invention is a sliding bearing in which a resin coating layer is provided on a sliding bearing base material having a backing metal and a bearing alloy layer disposed on the backing metal.

  As the binder resin in the resin coating layer, a resin having mechanical strength and high heat resistance is preferably used. Specific examples include thermosetting resins such as polyimide resin (PI), polyamideimide (PAI) resin, epoxy resin and phenol resin, and thermoplastic resins such as polybenzimidazole (PBI) and PES. (PI) or polyamideimide (PAI) resin is preferred from the viewpoint of mechanical strength and adhesion to the bearing alloy layer.

  The binder resin may be used alone or in combination of two or more. In the case of combination, PA resin or PI resin is combined with PAI resin or PI resin, and high shear is applied to form a polymer alloy. May be.

The solid lubricant is not particularly limited, and a commonly used solid lubricant can be used regardless of the presence or absence of orientation. Specific examples include molybdenum disulfide (MoS ₂ ), graphite, hexagonal boron nitride (h-BN), WS ₂ , and fluorine compounds. Among them, disulfide is low in terms of low friction and adhesion to the resin. Molybdenum (MoS ₂ ), graphite, and fluorine compounds are preferably used. As the fluorine compound, polytetrafluoroethylene (PTFE) is preferable. Moreover, a solid lubricant may be used by 1 type, or may be used in combination of 2 or more type.

  The total amount of the solid lubricant is preferably 50 to 300 parts by weight with respect to 100 parts by weight of the binder resin.

  In the present invention, the resin coating layer contains a wax in addition to the binder resin and the solid lubricant. By containing the wax, the sliding resistance with the counterpart shaft is reduced, so that the heat resistance of the resin coating layer is improved, and as a result, the seizure resistance can be improved. In addition, the addition of wax improves the wettability under lubricating conditions using lubricating oil or grease, which also contributes to the improvement of seizure resistance.

Examples of the wax include plant-based carbana wax, mineral-based paraffin wax, olefin wax, microcrystalline wax, synthetic petroleum-based polyethylene wax, polypropylene wax, and the like.
In particular, synthetic petroleum-based polyethylene wax and polypropylene wax are preferably used from the viewpoint of heat resistance.
The wax may be used alone or in combination of two or more.

  It is preferable that 0.1-15 weight part of wax is contained with respect to 100 weight part of binder resin, More preferably, it is 1-10 weight part. If it is less than the said upper limit, it is preferable from the point of the adhesiveness to a bearing alloy layer, and if it is more than the said lower limit, it is preferable from the point of an improvement of lubricity.

  The resin coating layer contains an antioxidant together with the wax. In the formation of the resin coating layer, a baking treatment is performed to cure the binder resin. However, since the wax has a property of being easily oxidized and decomposed at a high temperature, the wax is decomposed in this baking treatment and cannot remain in the resin coating layer. Or there is a possibility that it may be reduced from the charged amount. Therefore, in the present invention, by adding an antioxidant, the oxidative decomposition of the wax can be suppressed, the wax can be stably present in the resin coating layer, and the amount of the charged wax can be reduced.

It does not specifically limit as antioxidant, A phenolic antioxidant, an amine antioxidant, a phosphite antioxidant, a sulfur type antioxidant, etc. can be used.
As the phenolic antioxidant, “Sumilizer MDP-S2” (trade name) (Sumitomo Chemical, 2′-methylenebis (6-tert-4-methylphenol)), “Sumizer BBM-S” (trade name) (Sumitomo Chemical, 4,4′-Butylidenebis (6-tert-butyl-3-methylphenol)), “Sumilizer WX-R WX-RA WX-RC” (trade name) (Sumitomo Chemical, 4,4′- Thiobis (6-tert-butyl-3-methylphenol)), “Sumilizer NW (N)” (trade name) (Sumitomo Chemical, Alkylated bisphenol), “Sumilizer GA-80” (trade name) (Sumitomo Chemical, 3 , 9 Bis [2- [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1,1-dimethylethyl] -2,4,8,10-tetraxaspiro [5/5] undecane), “ IRGANOX "(trade name) (BASF)," IRGAMOD "(trade name) (BASF), and the like.
Examples of the amine-based antioxidant include “Sumilizer 9A” (trade name) (Sumitomo Chemical Co., Ltd., alkylated diphenylamine).
Examples of the sulfur-based antioxidant include “Sumilizer MB” (trade name) (Sumitomo Chemical Co., Ltd., 2-Mercaptobenzimidazole).
In addition, antioxidant may be used by 1 type or may be used in combination of 2 or more type.

  Content of antioxidant should just be 0.1-10 weight part with respect to 100 weight part of binder resin, and it is preferable that it is 1-5 weight part. An antioxidant within such a range is preferable from the viewpoint of the antioxidant function of the wax.

The resin coating layer is formed on the bearing alloy layer, but may have a single-layer structure having the above composition or a two-layer structure described below.
In the case of a two-layer structure, the upper layer (surface layer) preferably contains a wax and an antioxidant, and the lower layer (intermediate layer) preferably contains no wax. If a large amount of wax is added, the adhesion to the bearing alloy layer may be reduced. Therefore, the adhesiveness of the resin coating layer to the bearing alloy layer can be improved by providing the lower layer portion not containing the wax while improving the heat resistance by providing the upper layer containing the wax.
Further, the binder resin and the solid lubricant are preferably contained in both the upper layer and the lower layer.

Regardless of the number of resin coating layers, the thickness of the entire resin coating layer is preferably 3 to 20 μm from the viewpoint of wear resistance at the lower limit and fatigue resistance at the upper limit. In the case where the resin coating layer has a two-layer structure, the thickness of the lower layer is preferably 0.1 μm or more from the viewpoint of ensuring the adhesion between the resin coating layer and the lining layer. Moreover, since the heat resistance can be ensured by setting the thickness of the upper layer to 2.9 μm or more, it is preferable. Further, the thickness of the upper layer and the lower layer is preferably 10 μm or less.
The resin coating layer is provided on a bearing base material having a backing metal and a bearing alloy layer disposed on the backing metal. Here, as the back metal and the bearing alloy layer, various materials conventionally used in the field can be used under various conditions.

  The bearing alloy layer includes, for example, Al and Cu as a main component, and among them, an aluminum bearing alloy, a copper bearing alloy or the like can be used.

The composition of the aluminum-based bearing alloy is not particularly limited, but is a group consisting of 10% by mass or less of Cr, Si, Mn, Sb, Sr, Fe, Ni, Mo, Ti, W, Zr, V, Cu, Mg, Zn, and the like. An alloy containing one or more elements selected from the group consisting of 20% by mass or less and one or more elements selected from the group consisting of Sn, Pb, In, Tl, Bi, and the like can be preferably used.
The former group of elements mainly imparts strength and wear resistance, and the latter group of elements mainly imparts conformability, and exhibits bearing characteristics depending on the type and amount of elements added.
Further, the resin coating layer of the present invention can be used with the skirt portion of a piston made of a high Si—Al alloy such as AC8A or AC9B, which is an aluminum alloy casting, as a base, and the wear resistance can be improved.

The composition of the copper alloy is not particularly limited, but an alloy containing 25% by mass or less of Bi, 10% by mass or less of Sn, and 2% by mass or less of P, Ag, In, Ni, Al, or the like is preferably used. can do.
Among these elements, Bi, which is a soft metal, exhibits conformability, Sn, which is a basic component of bronze, exhibits high strength and wear resistance, and other components supplementarily improve characteristics. In particular, P is effective for deoxygenation, promotion of sintering, strengthening, etc. Ag forms a compound effective for improving sliding characteristics by reaction with lubricating oil or impurity component S in copper, and In is corrosion resistance and lubrication. Oil and wettability are improved, and Ni and Al have effects such as strengthening copper.

  The bearing alloy layer generally has a thickness of 0.2 mm to 0.5 mm. In general, the thickness of the backing metal that supports this can be appropriately selected according to the diameter of the mating shaft.

  The shape of the plain bearing of the present invention may be cylindrical or halved. When the bearing is halved, two halved plain bearings are combined into a cylindrical shape.

  When using the plain bearing of the present invention, the lubrication conditions are not particularly limited. Since the wax itself exhibits an effect as a lubricant, the effect is more exhibited in an environment where there is no lubricating oil or grease on the sliding surface. Even in an environment using lubricating oil or grease, the wettability between the wax and the lubricating oil is good, and the lubricating oil is retained as the entire resin coating layer, so that the performance of the bearing can be improved.

Although the manufacturing method of the sliding bearing concerning this invention is shown below, a manufacturing method is not limited to these methods.
(A) forming a bearing alloy layer on the back metal;
(B) forming a cylindrical or halved plain bearing base material by cutting or pressing, etc.,
(C) A step of applying a treatment for ensuring adhesion between the base material and the resin coating layer on the surface of the bearing alloy layer of the slide bearing base material;
(D) a step of applying a resin coating layer on the bearing alloy layer of the slide bearing substrate;
(E) a step of drying the resin coating layer,
(F) A step of firing the resin coating layer.
The order of the above steps may be changed, or other steps may be inserted therebetween.

  Examples of the step (c) include physical treatment represented by roughening treatment such as sand blasting, and chemical treatment such as etching and chemical conversion treatment. This treatment is preferably performed after degreasing the oil of the bearing base material with a cleaning agent.

  When applying the resin coating layer in the step (d), a coating liquid in which a solid lubricant, a binder resin, a wax, an antioxidant, and other optional components are mixed is prepared. In addition, a solvent such as methylpyrrolidone or xylene can be used as needed to enhance the dispersibility of the solid lubricant and the binder resin or to adjust the viscosity of the coating solution.

The application method is not particularly limited, and examples include an air spray method, an airless spray method, a roll method, a pad method, a screen printing method, electrostatic coating, and tumbling.
In addition, when the thickness is insufficient, a method in which the solid lubricant and the binder resin in the diluent are not increased in concentration but overcoated several times is preferably used.

  In the step (e), the solvent is evaporated by drying. In drying, the method is not particularly limited as long as the solvent evaporates. However, it is preferably performed at 40 to 120 ° C. for 5 to 60 minutes from the viewpoint of adhesion between the lining and the resin. Note that the temperature during drying may be constant within the above temperature range, or may be changed by raising the temperature.

In the step (f), the method is not particularly limited as long as the binder resin is cured, but may be performed at 150 to 300 ° C. for 30 to 60 minutes.
During this step, the temperature may be constant within the above range or may be changed in temperature, but it is preferably performed in an inert gas atmosphere such as nitrogen gas in order to prevent oxidation of additional components such as wax.

In addition, when making a resin coating layer into a two-layer structure, after passing through the process (d-1) of apply | coating the lower layer which does not contain a wax, and the process (e-1) of drying a lower layer after that, an upper layer is apply | coated. The method of passing through the process (d-2) and the process (f) which bakes an upper layer and a lower layer through the drying process (e-2) of an upper layer is mentioned.
Moreover, after the drying process (e-1) after lower layer application | coating (d-1), after passing once a baking process (f-1), an upper layer is apply | coated (d-2), a drying process (e-2), You may pass through a baking process (f-2).

  EXAMPLES The present invention will be specifically described below with reference to examples. However, the present invention is not limited to these examples.

(Preparation of resin composition coating solution)
Polyamideimide resin, solid lubricant, wax, and antioxidant were mixed at the composition ratio shown in Table 1 and sufficiently stirred. Thereafter, a coating solution of the resin composition was prepared using N-methyl-2pyrrolidone (NMP) as a diluent.
<Binder resin>
Polyamideimide resin: HR-13NX (trade name), Toyobo Co., Ltd. <solid lubricant>
MoS ₂ : M-5 powder (trade name) (Daizo)
Graphite: CSSP (trade name) (Central Glass Company)
Fluorine compound: Graphite fluoride (Cefbon CMA (trade name)) (Central Glass Co., Ltd.)
<Wax>
Degradable polypropylene wax: High Wax NP805 (trade name) (Mitsui Chemicals)
<Antioxidant>
Phenol antioxidant: IRGANOX 1330 (trade name) (BASF)

(Production of slide bearing)
An aluminum-based half bearing alloy was press-contacted to the back metal, and a half-shaped bearing base material was manufactured by cutting. At this time, the thickness of the entire bearing substrate was 1.5 mm, and the thickness of the aluminum bearing alloy layer was 0.3 mm. In order to ensure the adhesion between the bearing base material and the resin coating layer, the oil content of the bearing base material was degreased with a cleaning agent, and then the surface of the bearing alloy layer was roughened.
Thereafter, a coating solution for the resin coating layer was applied onto the bearing alloy layer by air spray. Then, it was dried at 120 ° C. for 30 minutes and baked at 200 ° C. for 0.5 hours in a nitrogen gas atmosphere to form a resin coating layer. The thickness of the resin coating layer after baking was 10 μm.

(Baking test)
The seizure test was performed under the following conditions using a bearing seizure tester.
Rotation speed: 10000rpm
Lubricating oil: 0W-20
Lubrication temperature: 140 ° C
Load: Gradually increase by 3 kN every 3 minutes

  The results of the seizure test are shown in Table 1 as the seizure surface pressure.

As shown in Table 1, the baking surface pressure was remarkably improved by adding a wax and an antioxidant (Examples 1 to 4).
Further, even when the blending amount of the wax was as small as 2 parts by weight with respect to 100 parts by weight of the polyamideimide resin (PAI), a remarkable improvement in the baking surface pressure was observed (Example 1, Comparative Example 1). This means that the wax was not decomposed even in the baking process at a high temperature, which is considered to be an effect due to the addition of the antioxidant.
From the above, it was confirmed that the seizure resistance is remarkably improved by adding a wax and an antioxidant to the coating layer containing the solid lubricant and the binder resin in the present invention.

Claims (3)

A sliding bearing having a resin coating layer on a sliding bearing base material having a backing metal and a bearing alloy layer provided on the backing steel,
The resin coating layer, a binder resin, a solid lubricant, seen waxy, and antioxidants,
A sliding bearing in which the resin coating layer has a two-layer structure, the upper resin coating layer contains the wax and the antioxidant, and the lower resin coating layer contains no wax .   The sliding bearing according to claim 1, wherein the resin coating layer has a thickness of 3 to 20 μm. The plain bearing according to claim 1 or 2 , wherein a thickness of the lower resin coating layer is 0.1 µm or more.