JP2008297369A - Foamed solid lubricant for universal joint and universal joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a foamed solid lubricant-sealed universal joint which has a long life, can be made at a low cost, is excellent in productivity, and can simultaneously achieve the reduction in loads on environments. <P>SOLUTION: This universal joint is characterized in that the foamed solid lubricant 10 is sealed on the periphery of a torque transmission member (ball) 6; the foamed solid lubricant 10 is produced by foaming and curing a mixture of a lubricating component, a resin component, a curing agent, and a foaming agent; the lubricating component is at least one lubricating component selected from lubricants and/or greases; the resin component is a urethane prepolymer having an isocyanate group content of ≥2 wt.% to <6 wt%; the foaming agent is water; the mixture contains the lubricating component in an amount of 30 to 70 wt.% based on the total amount of the mixture; and an open-cell rate is ≥50%, after foamed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a foamed solid lubricant for a universal joint and a universal joint (joint) in which the lubricant is sealed.

In recent years, technical improvements for higher performance, compactness and weight reduction of automobiles have progressed, and universal joints such as constant velocity joints used for drive transmission of automobile parts and industrial machines have also been reduced in size, performance and length. There is an increasing demand for longer life.
Along with the progress of downsizing and weight reduction, a high load is also applied to the universal joint, and it may be difficult to achieve a long life with conventional grease lubrication. Since higher performance will be required in the future, simply optimizing the amount of grease and additives will limit the prevention of lubricant scattering and dripping under high temperature, high speed, and high load operating environments. There is.
In order to solve such a problem, a lubricant-containing foam in which a solid component is foamed and filled with a lubricating oil has been reported (see Patent Document 1).
In this lubricant-containing foam, the solid foam is compressed following the boot that is deformed by the bending of the constant velocity joint. Here, the liquid lubricant present in the space of the foam is released and supplied to a necessary portion, thereby enabling good lubrication.

  The lubricant disclosed in Patent Document 1 is a post-impregnation type in which a foamed resin is impregnated with a lubricating oil. In the case of the post-impregnation type, the lubricating oil is impregnated in the foaming space of the foamed resin, but hardly impregnated in the foamed resin itself. For this reason, there is a problem that the lubricating oil retention force is small, such as when the affinity between the foamed resin and the lubricating oil is weak, and the lubricating oil escapes at a time when used under high speed conditions. Such a foamed lubricant can be used in a short time of lubrication or in a sealed space, but is difficult to use in a long time or in an open space. Further, since the oil retention is not high, the lubricant constantly flows in the space while repeating the release of the lubricant and the absorption into the foam. In such a case, depending on the chemical nature of the lubricating oil and the additives contained in it, there is a possibility that the boot material may be attacked and deteriorated, and there is a problem that the material selection of either the lubricant or the boot material is limited. is there. In addition, there are problems in that the number of man-hours in the manufacturing process associated with post-impregnation, the increase in manufacturing time, and the associated cost increase are unavoidable.

On the other hand, a lubricating composition in which a lubricating oil is contained in a polyurethane resin produced from a polyol component and an isocyanate component is known (see Patent Documents 2 to 5).
In addition, a hydroxyl-terminated polydiene compound has been reported as a raw material that can be oil-extended by bitumen or the like (see Patent Document 6).
However, there is no known solid foamed lubricant that has rubber elasticity that can be used at sites where external stress such as compression and bending acts, has high lubricant retention, and allows large deformation.

Therefore, a universal joint using a solid lubricant that has high lubricant retention and allows large deformation is required for the reasons described above. In particular, it is necessary to include lubricating oil or the like in the solid resin component to increase the lubricant retention.
In this way, the lubricant required for universal joints can supply the required amount to the required locations even compared to the grease lubrication that is widely used in the industry. This technology has the advantage of reducing costs by reducing the load, reducing the load on boot materials, and reducing the weight and size of universal joints. It can be said that this technology is highly socially important from multiple viewpoints.
Japanese Patent Laid-Open No. 9-42297 JP-A-60-173010 Japanese Patent Laid-Open No. 62-241997 JP-A-8-3259 JP-A-6-172770 JP 58-189243 A

  The present invention has been made in order to cope with such a problem, and is a foamed solid lubricant for a universal joint capable of achieving a long life, low cost, excellent productivity, and simultaneously reducing the environmental load. An object of the present invention is to provide a universal joint in which this lubricant is enclosed.

  The foamed solid lubricant for a universal joint of the present invention is transmitted with rotational torque by the engagement between the track groove and the torque transmission member, and is axially moved by rolling the torque transmission member along the track groove. This product is used by being sealed around the torque transmission member of a universal joint, and foamed and cured with a mixture containing a lubricating component, a resin component, a curing agent, and a foaming agent. Japanese Industrial Standard (JIS) K6400 The above-mentioned foamed solid lubricant measured according to the above has a tensile strength of 50 kPa or more, an elongation of 200% or more, and a 40% compression stress of less than 15 kPa.

Among the solid foam lubricants, the first solid foam lubricant is at least one lubricating component whose lubricating component is selected from hydrocarbon-based lubricants and hydrocarbon-based greases, and the resin component is a polymer main component. A liquid rubber having a chain composed of hydrocarbons and having a hydroxyl group amount of 25 mgKOH / g to 110 mgKOH / g at the end of the main chain, and the curing agent is an organic compound having an isocyanate group in the molecule The ratio of the liquid rubber and the curing agent is such that the hydroxyl group contained in the liquid rubber and the isocyanate group contained in the curing agent are equivalent (OH / NCO) = 1 / (1.0 to 2.0), and the mixture contains 40% to 80% by weight of the lubricating component and 5% to 45% by weight of the liquid rubber with respect to the whole mixture. To do.
Further, the liquid rubber is a hydroxyl group-terminated diene polymer having a number average molecular weight of 1000 to 3500 having a hydroxyl group at the main chain terminal of a butadiene or isoprene polymer, or a modified hydroxyl group-terminated diene system obtained by hydrogenating the diene polymer. It is a polymer.
The organic compound having an isocyanate group in the molecule is a prepolymer having two or more isocyanate groups in the molecule and a ratio of the isocyanate group of 2.5 NCO% to 5.0 NCO%, or aromatic. It is a polyisocyanate.

Among the foamed solid lubricants, the second foamed solid lubricant is at least one lubricating component in which the lubricating component is selected from lubricating oil and grease, and the resin component has an isocyanate group content of 2% by weight. More than 6% by weight of urethane prepolymer, the foaming agent is water, and the mixture contains 30% to 70% by weight of the lubricating component with respect to the whole mixture, and the open cell ratio after foaming is It is characterized by being 50% or more. The urethane prepolymer is at least one urethane prepolymer selected from an ester urethane prepolymer, a caprolactone urethane prepolymer, and an ether urethane prepolymer.
Further, the ratio of the isocyanate group to the functional group of the curing agent that reacts with the isocyanate group is an equivalent ratio (functional group of the curing agent / NCO) = 1 / (1.1 to 2.5). And
The ratio of the hydroxyl group of water to the functional group of the curing agent is an equivalent ratio (hydroxyl group of water / functional group of the curing agent) = 1 / (0.7 to 2.0).
The curing agent is an aromatic polyamino compound, particularly an aromatic polyamino compound having a substituent at a position adjacent to an amino group.

According to the universal joint of the present invention, the rotational torque is transmitted by the engagement between the track groove and the torque transmission member, and the torque transmission member, in which the foamed solid lubricant is enclosed, rolls along the track groove. It is characterized by axial movement.
The universal joint is a constant velocity universal joint (hereinafter also referred to as a constant velocity joint).
Further, the torque transmission member is a ball, and the ball is a fixed type of three, six or eight.

The foamed solid lubricant for a universal joint of the present invention is formed by foaming and curing a mixture containing a lubricating component, a resin component, a curing agent, and a foaming agent. Occluded in the ingredients. In the present invention, “occlusion” means that a liquid / semi-solid lubricating component does not react with other compounding components and is contained in a solid resin without becoming a compound.
In addition, since the tensile strength of the foamed solid lubricant measured according to JIS K6400 is 50 kPa or more, the elongation is 200% or more, and the 40% compression stress is less than 15 kPa. Lubricating oil is gradually released from the foamed solid lubricant to the outside in response to external stresses such as compression, bending and expansion that occur when the centrifugal force and the universal joint take an angle. As a result, the lubricant holding power is excellent, and the universal joint can be reduced in size, improved in performance and extended in life.
The foamed solid lubricant for universal joints of the present invention requires very little energy when bent compared to the solid lubricant for non-foamed universal joints, and can be flexibly deformed while maintaining a high density of lubricating components. is there. Therefore, in the process of cooling after solidifying the foamed solid lubricant for universal joints, even if the solid lubricant contracts and embraces the torque transmission member, it is easily deformed because the energy required for bending and deformation is small. This can prevent the problem that the torque applied to the universal joint increases.

  The foamed solid lubricant enclosed in the universal joint, particularly the constant velocity universal joint, is subjected to various forces when the constant velocity universal joint rotates at an angle. When the shaft rotates with an operating angle, each part reciprocates in the axial direction, so that the force acting on the foamed solid lubricant enclosed inside is not only greatly varied, but also tension, compression, bending, and shearing. Various forces will act. For this reason, the foamed solid lubricant to be encapsulated is required to have suitable physical properties.

The foamed solid lubricant for a universal joint of the present invention is used by being enclosed around the torque transmission member of the universal joint, and foams and cures a mixture containing a lubricating component, a resin component, a curing agent, and a foaming agent. The tensile strength of the foamed solid lubricant measured in accordance with Japanese Industrial Standard (JIS) K6400 is 50 kPa or more, preferably 65 kPa to 400 kPa, and the elongation is 200% or more, preferably 210% to 800. %, 40% compressive stress is less than 15 kPa, preferably 3 kPa to 13 kPa.
If the tensile strength and elongation deviate from the above ranges, the foamed solid lubricant breaks when the operating angle increases, and the universal joint cannot be lubricated where it needs to be lubricated.
If the 40% compression stress is 15 kPa or more, the temperature inside the universal joint rises due to self-heating of the foamed solid lubricant during compression, and the durability of the universal joint deteriorates.
In addition, when the tensile strength is 400 kPa or more, the elongation is 800% or more, and the 40% compression stress is 3 kPa, it may be difficult to design a material that satisfies each physical property value.

As the resin component constituting the foamed solid lubricant for a universal joint of the present invention, a resin component that has rubber-like elasticity after foaming and curing and has a leaching property of the lubricating component due to deformation is preferable.
Foaming / curing may be in a form in which foaming / curing is performed at the time of resin production, or in a form in which a foaming agent is added to the resin component and foaming / curing is performed in molding. In the present invention, a form that is foamed and cured at the time of resin production is preferred. Here, curing means a cross-linking reaction and / or a phenomenon in which a liquid is solidified. The rubber-like elasticity means rubber elasticity and means that deformation applied by an external force returns to the original shape by eliminating the external force.

As the resin component of the solid foam foamed lubricant for use in the present invention, it is preferable to use a urethane resin that is excellent in heat resistance and flexibility and can be reduced in cost. As a resin component, a first foamed solid lubricant using a liquid rubber having a hydroxyl group in the molecule described below and a second foamed solid lubricant using a urethane prepolymer containing a predetermined NCO are foamed solids for universal joints. Preferred as a lubricant.
Moreover, the resin component obtained by making the polyether polyol and polyisocyanate as a polyol react can be used.

As the resin component used for the first foamed solid lubricant, it is preferable to use a urethane resin that is excellent in heat resistance and flexibility and can be reduced in cost. The hydroxyl group-containing component that forms the urethane resin is preferably a liquid rubber having a hydroxyl group in the molecule, and the liquid rubber has a polymer main chain composed of hydrocarbons, and a hydroxyl value of 25 to 110 mgKOH / A liquid rubber having a hydroxyl group in an amount of g is preferred. When the hydroxyl value is less than 25 mg KOH / g, foaming / curing is not sufficient, and when the hydroxyl value exceeds 110 mg KOH / g, the elasticity of the foamed solid lubricant may be lost.
This liquid rubber is a hydroxyl group-terminated diene polymer having a number average molecular weight of 1000 to 3,500 having a hydroxyl group at the main chain terminal of a butadiene or isoprene polymer, or a modified hydroxyl group-terminated diene polymer obtained by hydrogenating the diene polymer. Coalescence can be used.
As the hydroxyl-terminated liquid polybutadiene, poly-bd R45HT (made by Idemitsu Kosan Co., Ltd.), poly-bd R15HT (made by Idemitsu Kosan Co., Ltd.), NISSO-PB G-1000, G-2000, G-3000 (made by Nippon Soda Co., Ltd.) are available. Examples of the hydroxyl group-terminated liquid polyisoprene include poly-ip (manufactured by Idemitsu Kosan Co., Ltd.). Examples of the hydrogenated hydroxyl group-terminated polydiene compound include Epol (manufactured by Idemitsu Kosan Co., Ltd.), NISSO-PB GI-1000, GI-2000, GI-3000 (made by Nippon Soda Co., Ltd.), etc. are mentioned.

  In addition, the hydroxyl group-terminated polydiene compound or the hydroxyl group-terminated polydiene compound obtained by partially modifying the hydroxyl group-terminated polydiene compound or the hydrogenated hydroxyl group-terminated polydiene compound with an isocyanate group or an epoxy group or the hydrogenated hydroxyl group-terminated polydiene compound are also included at the terminal. If it can be used. Two or more of these compounds may be mixed and used for the purpose of controlling the physical properties of the produced foam.

  The hydroxyl group-terminated polydiene polymer or the hydrogenated hydroxyl group-terminated polydiene polymer has a molecular structure similar to that of a lubricating component composed of paraffinic or naphthenic mineral oil composed of hydrocarbons, which will be described later. It is considered that the hydroxyl group-terminated polydiene polymer or the hydrogenated hydroxyl group-terminated polydiene polymer and the lubricating component molecule are intertwined by a relatively weak interaction. Therefore, many lubricating components can be impregnated in the molecule of the hydroxyl-terminated polydiene polymer or the hydrogenated hydroxyl-terminated polydiene polymer, and high lubricating component retention can be exhibited. By applying a strong force such as heat or centrifugal force to this, the interaction between the hydroxyl-terminated polydiene polymer or the hydrogenated hydroxyl-terminated polydiene polymer and the lubricating component is broken, and the lubricating component can be released gradually. it can.

The organic compound having an isocyanate group in the molecule as a curing agent for curing the liquid rubber can be used without particular limitation as long as it is an isocyanate compound that reacts with a hydroxyl group in the liquid rubber to extend the molecular chain or crosslink. Preferred isocyanate compounds include polyisocyanates. Polyisocyanates are particularly preferable because they can react with water to be a foaming agent described later to generate gas.
Examples of the polyisocyanates include polyisocyanates and / or prepolymers having two or more isocyanate groups in the molecule.

Polyisocyanates can include aromatic, aliphatic, or alicyclic polyisocyanates.
Aromatic polyisocyanates include tolylene diisocyanate (hereinafter referred to as TDI), diphenylmethane diisocyanate (hereinafter referred to as MDI), TDI multimer, MDI multimer, naphthalene diisocyanate (NDI), phenylene diisocyanate, diphenylene. And diisocyanate.
Examples of aliphatic polyisocyanates include octadecamethylene diisocyanate, decamethylene diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, and xylylene diisocyanate.
Examples of the alicyclic polyisocyanates include isophorone diisocyanate and dicyclohexylmethane diisocyanate.
Also, an adduct of the polyisocyanate and a polyol such as trimethylolpropane can be used.
When the reaction with the hydroxyl group that is the terminal functional group of the liquid rubber is performed at a high temperature, a blocked isocyanate or the like in which an isocyanate group is blocked with a blocking agent such as phenols, lactams, alcohols, and oximes can be used. .

  In the case of reacting with a hydroxyl group-terminated polydiene polymer, aromatic polyisocyanates are preferred among the polyisocyanates, and TDI having excellent foamability and reactivity with the hydroxyl group-terminated polydiene polymer is preferred.

As the prepolymer having two or more isocyanate groups in the molecule, any prepolymer having an isocyanate group ratio of 2.5 to 5.0 NCO% can be used. Here, NCO% means NCO wt% contained in the whole prepolymer. A 2.5 to 5.0 NCO% prepolymer can react with a hydroxyl group-terminated polydiene polymer or the like to obtain a urethane having high elasticity.
Prepolymers are classified into PPG type, PTMG type, ester type, caprolactone type, etc., depending on the type of monomer to be polymerized. There are Takenate L-1170 (manufactured by Mitsui Chemicals Polyurethane) and P-1158 (manufactured by Mitsui Chemicals Polyurethanes) in the PPG system, and Coronate 4090 (manufactured by Nippon Polyurethanes) in the PTMG system. Coronate 4047 (manufactured by Nippon Polyurethane Co., Ltd.) is used as the ester system, and Takenate L-1350 (manufactured by Mitsui Chemicals Polyurethanes Co., Ltd.), Takenate L-1680 (manufactured by Mitsui Chemicals Polyurethanes Co., Ltd.), and Sianaprene 7-QM are used as caprolactones. (Mitsui Chemical Polyurethane Co., Ltd.), Plaxel EP1130 (Daicel Chemical Industries Co., Ltd.) and the like. Two or more kinds of the above prepolymers can be mixed and used according to the purpose.

  The blending ratio of the hydroxyl group-terminated polydiene polymer having a terminal hydroxyl group or the hydrogenated hydroxyl group-terminated polydiene polymer and the isocyanate compound having an isocyanate group is equivalent ratio of hydroxyl group (—OH) to isocyanate group (—NCO). The range of (OH / NCO) = 1 / (1.0 to 2.0) is preferable, and the range of (OH / NCO) = 1 / (1.1 to 1.9) is preferable in consideration of particularly excellent foamability and elasticity. When (OH / NCO) is smaller than 1 / 2.0, the isocyanate group becomes excessive, the crosslink density is large, and the elasticity may be poor. On the other hand, when (OH / NCO) is greater than 1 / 1.0, the crosslinking groups are insufficient and curing is not sufficient.

The lubricating component that can be used for the first foamed solid lubricant can be used as long as it does not dissolve the solid component that forms the foam. Examples of the lubricating component include hydrocarbon-based lubricants, hydrocarbon-based greases, and mixtures of hydrocarbon-based lubricants and hydrocarbon-based greases.
Examples of the hydrocarbon-based lubricating oil include paraffinic and naphthenic mineral oils, hydrocarbon-based synthetic oils, GTL base oils, and the like. These can be used alone or as a mixed oil.
The hydrocarbon-based grease is a grease having a hydrocarbon oil as a base oil, and examples of the base oil include the above-described hydrocarbon-based lubricating oil. Examples of the thickener include lithium soaps, lithium complex soaps, calcium soaps, calcium complex soaps, aluminum soaps, aluminum complex soaps, and other urea compounds such as diurea compounds and polyurea compounds. It is not a thing. The diurea compound is obtained by the reaction of diisocyanate and monoamine, and the polyurea compound is obtained by the reaction of diisocyanate and polyamine.

  As the lubricating component, hydrocarbon synthetic wax, polyethylene wax, higher fatty acid ester wax, higher fatty acid amide wax, ketone / amines, hydrogenated oil, and the like can be mixed and used.

  Since the means for foaming the first foamed solid lubricant uses an isocyanate compound as a raw material, it is preferable to use water that reacts with the isocyanate compound to generate carbon dioxide gas.

The first solid foam lubricant is obtained by foaming and curing a mixture containing the above-described lubricating component, liquid rubber, a curing agent, and a foaming agent.
The blending ratio of the lubricating component is 40 to 80% by weight based on the entire mixture. If the lubricating component is less than 40% by weight, the supply amount of lubricating oil and the like is so small that it cannot function as a foamed solid lubricant, and if it exceeds 80% by weight, it will not solidify.
The blending ratio of the liquid rubber is 5 to 45% by weight, preferably 9 to 42% by weight, based on the entire mixture. When it is less than 5% by weight, it does not solidify, so it does not have a function as a foamed solid lubricant. When it is more than 45% by weight, the supply of the lubricant is small and it does not function as a foamed solid lubricant.

  In the first foamed solid lubricant, the expansion ratio is preferably 1.1 to 50 times, more preferably 1.1 to 10 times. When the expansion ratio is less than 1.1 times, the bubble volume is small and deformation cannot be allowed when external stress is applied. If it exceeds 50 times, it will be difficult to obtain the strength to withstand external stress.

  Moreover, in order to accelerate the curing rate of the first foamed solid lubricant, a tertiary amine catalyst, an organometallic catalyst, or the like can be used. Examples of the tertiary amine catalyst used include monoamines, diamines, triamines, cyclic amines, alcohol amines, ether amines and the like. Examples of the organometallic catalyst include stanaoctaate, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin mercaptide, dibutyltin thiocarboxylate, dibutyltin maleate, dioctyltin dimercaptide, dioctyltin thiocarboxylate and the like. Moreover, you may mix and use these multiple types for the purpose of adjusting the balance of reaction.

The urethane prepolymer that can be used as the resin component of the second foamed solid lubricant of the present invention is obtained by a reaction between a compound having an active hydrogen group and a polyisocyanate, and the isocyanate group may be a molecular chain terminal, or It may be contained at the end of the side chain branched from the molecular chain. The urethane prepolymer may have a urethane bond in the molecular chain.
Depending on the type of monomer (= compound having an active hydrogen group) to be reacted, it is classified into caprolactone, ester and ether. Examples of ethers include Takenate L-1170 (Mitsui Chemical Polyurethane), L-1158 (Mitsui Chemical Polyurethane), Coronate 4090 (Nippon Polyurethane). Coronate 4047 (manufactured by Nippon Polyurethane Co., Ltd.) is used as the ester system, and Takenate L-1350 (manufactured by Mitsui Chemicals Polyurethanes Co., Ltd.), Takenate L-1680 (manufactured by Mitsui Chemicals Polyurethanes Co., Ltd.), and Sianaprene 7-QM are used as caprolactones. (Manufactured by Mitsui Chemicals Polyurethane), Plaxel EP1130 (manufactured by Daicel Chemical Industries) and the like.
In addition, oligomers or prepolymer compounds whose terminal groups are modified to isocyanate groups can also be used. Examples of such a compound include a terminal isocyanate-modified polyether polyol and an isocyanate-modified product of a hydroxyl group-terminated polybutadiene. Examples of the terminal isocyanate-modified polyether polyol include Coronate 1050 (manufactured by Nippon Polyurethane Co., Ltd.). Moreover, poly-bd MC50 (manufactured by Idemitsu Kosan Co., Ltd.) and poly-bd HTP9 (manufactured by Idemitsu Kosan Co., Ltd.) can be mentioned as isocyanate-modified products of hydroxyl-terminated polybutadiene.
These urethane prepolymers can be used in a mixture of two or more depending on the intended mechanical properties.

As the second foamed solid lubricant, a urethane prepolymer having an isocyanate group content of 2 wt% or more and less than 6 wt% can be used. If the isocyanate group (NCO) content is less than 2% by weight, it will be difficult to achieve both foamability and elasticity, and if it is more than 6% by weight, the hardness will be too high and the rebound resilience will increase and deformation due to external force will occur. It becomes easy to generate heat when receiving.
Moreover, the isocyanate group can use the block isocyanate etc. which blocked the isocyanate group with blocking agents, such as phenols, lactams, alcohols, and oximes.

The curing agent for curing the urethane prepolymer is preferably a compound having active hydrogen, and examples thereof include a polyamino compound having a functional group as an amino group and a polyol compound having a functional group as a hydroxyl group.
Polyamino compounds include 3,3'-dichloro-4,4'-diaminodiphenylmethane (hereinafter referred to as MOCA), 3,3'-dimethyl-4,4'-diaminodiphenylmethane, and 3,3'-dimethoxy-4. , 4'-diaminodiphenylmethane, 4,4'-diamino-3,3'-diethyl-5,5'-dimethyldiphenylmethane, trimethylene-bis- (4-aminobenzoate), bis (methylthio) -2,4- Aromatics typified by toluenediamine, bis (methylthio) -2,6-toluenediamine, methylthiotoluenediamine, 3,5-diethyltoluene-2,4-diamine, 3,5-diethyltoluene-2,6-diamine Examples include polyamino compounds.

  Among the polyamino compounds, aromatic amino compounds are preferable because of low cost and excellent physical properties, and aromatic diamino compounds having a substituent at the position adjacent to the amino group are particularly preferable. In the 2nd foaming solid lubricant, since it passes through the process of hardening with foaming, it is thought that the reactivity of an amino group is suppressed by the substituent of an adjacent position.

  When the urethane prepolymer is cured with a polyamino compound, it becomes a foamed solid lubricant having urethane and urea bonds in the molecule. By generating urea bonds, the urethane bond density in the molecule is lowered, and elongation and impact resilience are improved. Moreover, rigidity can be provided by generating a urea bond.

  Examples of the polyol compound include low molecular polyols such as 1,4-butane glycol and trimethylolpropane, polyether polyols, castor oil polyols, and polyester polyols. Among the polyol compounds, polyether polyol and trimethylolpropane are preferable.

The ratio of the isocyanate group (—NCO) contained in the urethane prepolymer and the functional group of the curing agent that reacts with the isocyanate group is an equivalent ratio when the functional group is an amino group or a hydroxyl group (functional group of the curing agent). /NCO)=1/(1.1 to 2.5).
The ratio of the isocyanate group contained in the urethane prepolymer, the amino group (—NH ₂ ) or hydroxyl group (—OH) of the curing agent, and the hydroxyl group of water (—OH) as the foaming agent, Flexibility, elasticity, etc. are determined. When the amino group (—NH ₂ ) or hydroxyl group (—OH) of the curing agent is reacted with the isocyanate group (—NCO) of the urethane prepolymer in an equivalent amount, an isocyanate group (—NCO) that reacts with water as the foaming agent is formed. Since it will disappear, the range of (functional group of curing agent / NCO) = 1 / (1.1 to 2.5) is preferable. Moreover, the ratio of the hydroxyl group of water which is a foaming agent and the functional group of a hardening | curing agent is the range of (hydroxyl group of water / functional group of a hardening | curing agent) = 1 / (0.7-2.0) by an equivalent ratio.
If the amount of the curing agent is less than the above range, not only the physical properties such as the strength of the foamed solid lubricant are remarkably lowered, but also the urethane elastomer may not be cured.

The lubricating component that can be used in the second foamed solid lubricant can be used as long as it does not dissolve the solid component that forms the foam, like the first foamed solid lubricant. As the lubricating component, for example, lubricating oil, grease, wax or the like can be used alone or in combination. Particularly preferred are hydrocarbon-based lubricants, hydrocarbon-based greases, or mixtures of hydrocarbon-based lubricants and hydrocarbon-based greases.
As the hydrocarbon-based lubricant, the same one as the first foamed solid lubricant can be used. In addition, ester synthetic oils, ether synthetic oils, fluorine oils, silicone oils and the like can also be used. These can be used alone or as a mixed oil.
As the grease, in addition to the grease similar to the first foamed solid lubricant, a grease based on ester synthetic oil, ether synthetic oil, GTL base oil, fluorine oil, silicone oil or the like can be used.
In addition, the same hydrocarbon-based synthetic wax, polyethylene wax, higher fatty acid ester-based wax, higher fatty acid amide-based wax, ketone / amines, hydrogenated oil, and the like as the first foamed solid lubricant may be used. it can.

As the foaming agent for foaming the second foamed solid lubricant, since an isocyanate compound is used as a raw material, it is preferable to use water that reacts with the isocyanate compound to generate carbon dioxide gas.
Moreover, in order to accelerate the curing rate of the second foamed solid lubricant, the above-described tertiary amine catalyst, organometallic catalyst, or the like can be used.

The second foamed solid lubricant is obtained by foaming and curing a mixture containing the lubricating component, the resin component, the curing agent, and the foaming agent.
The blending ratio of the lubricating component is 30 to 70% by weight, preferably 40 to 60% by weight, based on the entire mixture. If the lubricating component is less than 30% by weight, the supply amount of lubricating oil and the like is so small that it cannot function as a foamed solid lubricant, and if it exceeds 70% by weight, it does not solidify.

  The open cell ratio of the second foamed solid lubricant after foaming is 50% or more. More preferably, it is 50% or more and 90% or less. When the open cell ratio is less than 50%, the ratio of the resin component (solid component) lubricating oil temporarily taken up into the closed cells increases and may not be supplied to the outside when necessary. If it exceeds 90%, the strength of the foam itself tends to decrease, and the holding power of the lubricating component decreases, so that the release of the lubricating component increases, which is disadvantageous for long-term use.

The open cell ratio of the second solid foam lubricant can be calculated by the following procedure.
(1) The foamed solid lubricant that has been foam-cured is cut into an appropriate size to obtain sample A. The weight of sample A is measured.
(2) A is soxhlet washed (solvent: petroleum benzine) for 3 hours. Thereafter, the sample is left in a thermostatic bath at 80 ° C. for 2 hours to completely dry the organic solvent, and sample B is obtained. The weight of sample B is measured.
(3) The open cell ratio is calculated by the following procedure.
Open cell ratio = (1− (weight of resin component of sample B−weight of resin component of sample A) / weight of lubricating component of sample A) × 100
The resin component weight and the lubrication component weight of Samples A and B are calculated by multiplying the weights of Samples A and B by the composition charge ratio.
Lubricating components taken into discontinuous closed cells are not released to the outside by Soxhlet cleaning for 3 hours, so the weight of sample B is not reduced. The open cell ratio can be calculated as a result of the release of the lubricating component.

The first and second foamed solid lubricants may contain various additives such as pigments, antistatic agents, flame retardants, antifungal agents, reinforcing agents, inorganic fillers, anti-aging agents, and fillers as necessary. Can be added. Examples of the reinforcing agent include carbon black, white carbon, colloidal silica, and examples of the inorganic filler include calcium carbonate, barium sulfate, talc, clay, and meteorite powder.
In addition, solid lubricants such as molybdenum disulfide and graphite, friction modifiers such as organic molybdenum, oily agents such as amines, fatty acids, and fats, antioxidants such as amines and phenols, petroleum sulfonates, dinonylnaphthalene sulfone Antirust agents such as nates and sorbitan esters, extreme pressure agents such as sulfur and sulfur-phosphorus, antiwear agents such as organic zinc and phosphorus, metal deactivators such as benzotriazole and sodium nitrite, polymethacrylate, polystyrene Various additives such as a viscosity index improver such as

For the first and second foamed solid lubricants, it is possible to use a reactive impregnation method in which a foaming reaction and a curing reaction are simultaneously performed in the presence of a lubricating component such as a lubricating oil. It is desirable to achieve both elongation simultaneously. This is because the lubricant is uniformly impregnated into the foam formed in the foam during the foam formation stage, and the lubricant is occluded in the foamed / cured solid component, so that the lubricant is highly filled and the material properties It is considered that the high elongation of both is compatible.
On the other hand, after the foam is manufactured in advance, the post-impregnation method in which the lubricant is impregnated does not have sufficient lubricant holding power, and the lubricant is released in a short period of time and supplied when used for a long time. It becomes insufficient.

Examples of using the universal joint of the present invention for a constant velocity joint include a ball fixed joint (hereinafter referred to as BJ), an undercut free joint (hereinafter referred to as UJ), and the like. The number of torque transmitting members (balls) of such BJ and UJ may be 6 or 8.
When a foamed solid lubricant is sealed in BJ or UJ, the lubricant is filled only in the necessary parts, which contributes to cost reduction and weight reduction, and because the operating angle used is large, it is compressed.・ It is easy to bend and the lubricant is easily supplied to the sliding part.
Examples of use for the sliding constant velocity joint include a double offset joint (hereinafter referred to as DOJ), a tripod joint (hereinafter referred to as TJ), and a cross groove joint. The number of DOJ torque transmission members (balls) may be six or eight.
Moreover, a cross joint etc. are mentioned as an inconstant velocity joint.

The universal joint of this invention is demonstrated based on FIGS. 1-3. 1 is a partially cutaway sectional view of BJ, FIG. 2 is a partially cutaway sectional view of DOJ, and FIG. 3 is a partially cutaway sectional view of TJ.
As shown in FIG. 1, BJ1 forms six track grooves 4, 5 in the axial direction at equal angles on the inner surface of the outer ring as the outer member 2 and the outer surface of the inner ring as the spherical inner member 3. A torque transmission member 6 incorporated between the track grooves 4 and 5 is supported by a cage 7, the outer periphery of the cage 7 is a spherical surface 7 a, and the inner periphery is a spherical surface 7 b that matches the outer periphery of the inner member 3.
Further, the outer periphery of the outer member 2 and the outer periphery of the shaft 8 are covered with a boot 9, and the outer member 2, the spherical inner member 3, the track grooves 4 and 5, the torque transmission member 6, and the cage 7 The foamed solid lubricant 10 is enclosed in a space surrounded by the shaft 8.

As shown in FIG. 2, the DOJ 11 has six track grooves 14 and 15 in the axial direction formed at equal angles on the inner surface of the outer ring as the outer member 12 and the outer surface of the inner ring as the spherical inner member 13. The torque transmission member 16 incorporated between the track grooves 14 and 15 is supported by a cage 17, the outer periphery of the cage 17 is a spherical surface 17a, and the inner periphery is a spherical surface 17b that matches the outer periphery of the inner member 13, and each spherical surface 17a. , 17b are shifted in the axial direction on the axis of the outer member 12 (b).
The outer periphery of the outer member 12 and the outer periphery of the shaft 18 are covered with a boot 19, and the outer member 12, the spherical inner member 13, the track grooves 14 and 15, the torque transmission member 16, and the cage 17 The foamed solid lubricant 20 is enclosed in a space surrounded by the shaft 18.

As shown in FIG. 3, the TJ 21 has three cylindrical track grooves 23 in the axial direction formed at equal angles on the inner surface of the outer ring as the outer member 22, and is attached to a tripod member 24 incorporated inside the outer member 22. Has three leg shafts 25, a spherical roller 26 as a torque transmission member is fitted to the outside of each leg shaft 25, and a needle 27 is interposed between the spherical roller 26 as the torque transmission member and the leg shaft 25. The spherical roller 26 which is a built-in torque transmission member is supported rotatably and slidable in the axial direction, and the spherical roller 26 which is the torque transmission member is fitted in the track groove 23.
Further, the outer periphery of the outer member 22 and the outer periphery of the shaft 28 are covered with a boot 29, and a foamed solid lubricant 30 is formed in a space surrounded by the outer member 22, the track groove 23, the tripod member 24, and the shaft 28. Is enclosed.

For such TJ and DOJ, the space in the joint is large due to the need to slide in the axial direction, and when existing lubricants such as grease are used, they are sealed more than fixed joints such as BJ described above. The amount increases.
However, since the foamed solid lubricant (10 in FIG. 1, 20 in FIG. 2, 30 in FIG. 3) can be filled only in the necessary portions, it is low when encapsulating the foamed solid lubricant in DOJ or TJ. The contribution to cost reduction and weight reduction becomes larger.

The universal joint of the present invention includes a mixing step of mixing each component of the raw material to obtain a mixture, a filling step of filling the mixture around the torque transmission member before the foaming and curing of the mixture is completed, It is manufactured by a foaming / curing step of foaming / curing the filled mixture to obtain a solid.
In the universal joint of the present invention, a predetermined space of the subassembly assembled only around the torque transmission member of the above-mentioned various universal joints is filled with a mixture of at least a urethane prepolymer, a curing agent, a lubricating component, and a foaming agent. After curing, it is obtained by assembling a member such as a boot. Since the mixture is simply filled into the universal joint sub-assembly and foamed / cured, it can be easily filled into any part of the universal joint with a complicated shape. The resulting universal joint already contains a lubricant. Is impregnated. For this reason, a molding die for obtaining a foamed molded product, a post-impregnation step of a lubricant, and the like are unnecessary.

The said mixing process is a process of mixing each component of a raw material and obtaining a mixture. A method of mixing a mixture containing a lubricating component, a urethane prepolymer having an isocyanate group in the molecule, a curing agent, and a foaming agent is not particularly limited, and for example, a Henschel mixer, a ribbon mixer, a juicer mixer, a mixing Mixing can be performed using a generally used stirrer such as a head.
For the mixture, it is desirable to use a surfactant such as a commercially available silicone foam stabilizer, and to uniformly disperse each raw material molecule. Further, the surface tension can be controlled by the type of the foam stabilizer, and the type of the generated bubbles can be controlled to open cells or closed cells. Examples of such surfactants include anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants, silicone surfactants, and fluorine surfactants.

  The filling step is a step of filling an arbitrary part of the universal joint subassembly before the mixture is foamed and cured. Since the mixture before foaming / curing is fluid, it can be easily filled into any part of a universal joint having a complicated shape. In addition, when filling the mixture, it can be formed into a predetermined shape by covering the side surface of the predetermined space in the universal joint sub-assembly with a jig such as a metal fitting as necessary.

The foaming / curing step is a step of foaming / curing the filled mixture in the universal joint sub-assembly.
As the means for foaming the resin component, the above-described foaming means can be employed. In the present invention, a compound having a highly reactive isocyanate group is used as a raw material, and chemical foaming by carbon dioxide generated by a chemical reaction between an isocyanate compound and water molecules is used. Moreover, when using foaming with such a reaction, it is preferable to use the above-mentioned catalyst as needed. Moreover, it is preferable that the bubble obtained by foaming is the above-mentioned open cell.

Further, in the above manufacturing method, as a method other than filling the mixture into the universal joint sub-assembly, there is a method in which the foamed solid lubricant formed by foaming and curing after filling into the molding die is incorporated into the universal joint.
There is also a method of foaming and curing the mixture at normal pressure without using a molding die. In this case, it is necessary to post-process the foamed / cured product into the desired shape by cutting or grinding, and incorporate it into the universal joint. There is. In the case of post-processing, the lubricant may leak during processing. In this case, it is necessary to ensure a predetermined amount of lubricant by post-impregnation.
These methods require a jig such as a molding die, and require post-processing such as grinding, post-impregnation, and incorporation. In addition, even if the cured foam is added by post-impregnation with a lubricant, problems such as low lubricant retention and easy leakage of the lubricant from the foam during handling for incorporation into a universal joint occur. Cheap.
From the above, in the present invention, it is preferable to adopt a method in which the mixture is filled into the universal joint sub-assembly and foamed and cured in terms of quality, work and cost.

  Even if the conventional universal joint causes grease to flow out due to damage to the boot, resulting in poor lubrication, the universal joint of the present invention releases the lubricant gradually, so that the damage to the boot is a direct factor in life. It also serves as a seal against intrusion of dust and moisture from the outside.

  In the universal joint of the present invention, the lubricating component contained in the foamed solid lubricant impregnated does not rapidly exude even when the foam is deformed by an external force, and the lubricating component is efficiently exuded on the sliding surface. It can be used. As a result, it is possible to obtain a universal joint that requires a minimum amount of lubricating components, has a long life, and has little deterioration in rubber boots. For this reason, the universal joint of the present invention can be used for various industrial universal joints, preferably for automobile universal joints, and particularly preferably for automobile constant velocity joints.

EXAMPLES The present invention will be further described below with reference to examples of the present invention, but the present invention is not limited thereby.
Examples 1 to 15 and Comparative Examples 1 to 4
The lubricating components, liquid rubber, curing agent, foaming agent, and catalyst used in Examples 1 to 15 and Comparative Examples 1 to 4 are shown below. In addition, () represents an abbreviation in the table.
Lubricating component Lubricating oil (lubricating oil): Turbine 100 (manufactured by Nippon Oil Corporation)
Lubricating grease (Grease 1): NTG2218M (manufactured by Kyodo Yushi Co., Ltd.)
Liquid rubber Hydroxyl-terminated polybutadiene (PBOH1): Poly-bd R45HT (hydroxyl value: 46.6 mgKOH / g, number average molecular weight: 2,800, manufactured by Idemitsu Kosan Co., Ltd.)
Hydroxyl-terminated polybutadiene (PBOH2): Poly-bd R15HT (hydroxyl value: 102.7 mgKOH / g, number average molecular weight: 1,200, manufactured by Idemitsu Kosan Co., Ltd.)
Hydroxyl-terminated polyisoprene (PipOH): Poly-ip (hydroxyl value: 46.6 mgKOH / g, number average molecular weight: 2,500, manufactured by Idemitsu Kosan Co., Ltd.)
Hydrogenated hydroxyl-terminated polyisoprene (HPipOH): Epol (hydroxyl value: 50.5 mgKOH / g, number average molecular weight: 2,500, manufactured by Idemitsu Kosan Co., Ltd.)
Curing agent Isocyanate compound (TDI): Coronate T-80 (manufactured by Nippon Polyurethane Co., Ltd.)
Elastomer 1 (UE1): Coronate 4090 (4.4 NCO% made by Nippon Polyurethane)
Elastomer 2 (UE2): Plaxel EP1130 (3.3 NCO% manufactured by Daicel Chemical Industries)
Foaming agent (foaming agent) Ion exchange water foam stabilizer (foam stabilizer) SRX298 (manufactured by Toray Dow)
Catalyst (Catalyst 1) DM70 (manufactured by Tosoh Corporation)

Mix well the compounding materials except the curing agent (isocyanate) at the blending ratios shown in Tables 1 to 3, and finally add 40 g of the mixture that was quickly mixed by adding the curing agent to a polytetrafluoroethylene resin container (70 mm in diameter). × Height 150 mm). After a few seconds, the foaming reaction started and allowed to stand at room temperature for several hours to be cured to obtain a cylindrical test piece. This test piece was observed visually and using an optical microscope. Evaluate a foam with elastic rubber that exudes oil when a force of 30 N is applied to the specimen in the direction of the cylindrical axis of the specimen and mark it as an excellent foamed solid lubricant. Moreover, the case where it does not harden as a foam and the case where the lubricating oil does not separate or release is marked with “X” and also shown in Tables 1 to 3.
In addition, the test piece evaluated as “◯” showed no oil oozing even when it was stretched 20% in the direction of the cylinder axis of the test piece.

As shown in Tables 1 to 3, the foamed solid lubricants of Examples 1 to 15 are elastic rubber foams in which oil oozes out when a corresponding force is applied when pressed with a finger. Although it was recognized as an excellent foamed solid lubricant, in Comparative Examples 1 to 4, it was found that although foamed, it did not partially solidify and function as a foamed solid lubricant.
The foamed solid lubricants of Examples 1 to 15 measured according to JIS K 6400 had a tensile strength of 50 kPa or more, an elongation of 200% or more, and a 40% compression stress of less than 15 kPa. .
Next, 17.0 g of the solid foamed lubricant component of Examples 1 to 15 was sealed in 8 fixed ball joint subassies (NTN Corporation, EBJ82 outer diameter size 72.6 mm) shown in FIG. After a few seconds, the foaming reaction started, and after standing at 100 ° C. for 30 minutes to foam and cure, other members such as boots and shafts were assembled to obtain a constant velocity joint for testing in which a foamed solid lubricant was enclosed.
Since this universal joint was filled with a foamed solid lubricant, it could be continuously operated in an actual machine durability test under the condition of an operation time of 300 hours described in Example 16 described later.

Examples 16 to 30 and Comparative Examples 5 to 7
The lubricating components, urethane prepolymers, curing agents, blowing agents, and catalysts used in Examples 16 to 30 and Comparative Examples 5 to 7 are shown below. In addition, () represents an abbreviation in the table.
Lubricating component Lubricating oil (lubricating oil 1): Turbine 100 (paraffinic mineral oil, manufactured by Nippon Oil Corporation)
Lubricating oil (lubricating oil 2): Crisef 150 (Naphthenic mineral oil, manufactured by Nippon Oil Corporation)
Lubricating oil (lubricating oil 3): Sinfluid 801 (poly-α-olefin, manufactured by Nippon Steel Chemical Co., Ltd.)
Lubricating grease (Grease 2): Pyronock Universal N6C (manufactured by Nippon Oil Corporation)
Urethane prepolymer Caprolactan-based urethane prepolymer 1 (prepolymer 1): Plaxel EP1130 (NCO 3.3%, manufactured by Daicel Chemical Industries)
Ether-based urethane prepolymer (Prepolymer 2): Coronate 4090 (NCO 4.3%, manufactured by Nippon Polyurethane)
Ester urethane prepolymer (Prepolymer 3): Coronate 4047 (NCO 4.3%, manufactured by Nippon Polyurethane Co., Ltd.)
Caprolactan urethane prepolymer (Prepolymer 4): Takenate L-1350 (NCO 2.3%, manufactured by Mitsui Chemicals Polyurethanes)
Ether-based urethane prepolymer (Prepolymer 5): Takenate L-1170 (NCO 2.4%, manufactured by Mitsui Chemicals Polyurethanes)
Caprolactan urethane prepolymer (Prepolymer 6): Takenate L-1680 (NCO 3.2%, manufactured by Mitsui Chemicals Polyurethanes)
Caprolactan urethane prepolymer (Prepolymer 7): Cyanaprene 7-QM (NCO 2.3%, manufactured by Mitsui Chemicals Polyurethanes)
Hardener MOCA (MOCA): Iharacamine MT (manufactured by Ihara Chemical)
Trimethylene-bis- (4-aminobenzoate) (CUA-4): CUA-4 (manufactured by Ihara Chemical)
Mixture of bis (methylthio) -2,4-toluenediamine, bis (methylthio) -2,6-toluenediamine and methylthiotoluenediamine (Etacure 300): Etacure 300 (manufactured by Albemarle)
Trimethylolpropane: Reagent blowing agent (foaming agent) Ion exchange water foam stabilizer (foam stabilizer) SRX298 (manufactured by Toray Dow)
Catalyst (Catalyst 1) DM70 (manufactured by Tosoh Corporation)

  The urethane prepolymer, foam stabilizer, lubricating oil, and grease were mixed well at the blending ratios shown in Table 4 and Table 5, and then the curing agent was added and mixed quickly. When the curing agent was MOCA, the mixing temperature was 80 ° C., and MOCA was dissolved and added at 120 ° C. When the curing agent was CUA-4, the mixing temperature was 100 ° C., and CUA-4 was dissolved and added at 140 ° C. When the curing agent was Etacure 300 and trimethylolpropane, the mixing temperature was 80 ° C. Finally, after adding a foaming agent and an amine catalyst and stirring, the fixed eight ball joint subassembly (NTN Corporation) shown in FIG. 1 in which the outer member 2, the inner member 3, the cage 7 and the torque transmission member 6 are assembled. 17.0 g was sealed in an EBJ82 outer diameter size of 72.6 mm). After a few seconds, the foaming reaction started, and after standing at 100 ° C. for 30 minutes to foam and cure, other members such as boots and shafts were assembled to obtain a constant velocity joint for testing in which a foamed solid lubricant was enclosed. Using this test constant velocity joint, the following high angle test and actual machine durability test were conducted to evaluate the durability in the actual machine. The results are shown in Tables 4 and 5. Further, the tensile strength, elongation and 40% compression stress of the solid foam lubricant were measured by the following methods. Further, the open cell ratio of the foamed solid lubricant was measured based on the above-mentioned method for calculating the open cell ratio. The results are shown in Tables 4 and 5.

Comparative Example 5
A test constant velocity joint was obtained in the same manner as in Example 16 except that foaming / curing was carried out without using a lubricating oil, followed by post-impregnation with a lubricating oil. Using this constant velocity joint for testing, the actual machine durability test shown below was performed, and the durability in the actual machine was evaluated. The results are also shown in Table 5.

<Measurement of tensile strength and elongation>
The foamed solid lubricant was cut into a test piece having a width of 13 to 15 mm, a height of 10 to 15 mm, and a length of about 70 mm, and a test was conducted in accordance with JIS K6400-5 to determine tensile strength and elongation. The results are shown in Tables 4 and 5.
<Measurement of 40% compression stress>
The foamed solid lubricant was adjusted to a diameter of 70 mm and a height of 20 mm, and tested in accordance with JIS K6400-2 to obtain a 40% compression stress value. The results are shown in Tables 4 and 5.
<High angle test 1>
The test constant velocity joint was operated on a bench at a torque load of 0 N · m, a rotation speed of 200 rpm, an angle of 30 deg, and an operation time of 10 hours. The case where the temperature change of the outer ring was less than 10 ° C was marked as ◯. The results are shown in Tables 4 and 5.
<High angle test 2>
The test constant velocity joint was operated on a bench with a torque load of 0 N · m, a rotation speed of 80 rpm, and an angle of 40 deg. The foamed solid lubricant after the test encapsulated in the constant velocity joint was visually confirmed, and those that were not broken were marked with ◯. The results are shown in Tables 4 and 5.

<Real machine durability test>
The test constant velocity joint was subjected to an actual machine durability test under the conditions of a torque load of 186 N · m, a rotational speed of 1700 rpm, an angle of 6 deg and an operating time of 300 hours. Check the inside of the constant velocity joint for the test after the test, mark “Yes” for those that can continue operation, “X” for those that are severely damaged and impossible to continue operation, and outward during the test. When the surface temperature of the member exceeded 100 ° C., an abnormal temperature rise was not permitted, and “x” was also shown in Tables 4 and 5.

  Examples 16 to 30 showed good results in an endurance test using an actual machine. Since Comparative Examples 5 to 7 did not satisfy all the conditions that the tensile strength was 50 kPa or more, the elongation was 200% or more, and the 40% compression stress was less than 15 kPa, it was suitable for the high angle test 1. However, it broke in the high-angle test 2, and the damage was great in the actual machine durability test.

  The universal joint according to the present invention can efficiently exude the lubricating component, the amount of the lubricating component is the minimum necessary, and can maintain the lubricity for a long period of time, so that the stranded wire machine, the electric device, the printing machine, the automobile It can be suitably used as a universal joint for various industrial machines such as parts, electrical equipment, and construction machines, particularly as a constant velocity joint for automobiles.

It is sectional drawing of the constant velocity joint which concerns on one Example of this invention. It is sectional drawing of the constant velocity joint which concerns on the other Example of this invention. It is sectional drawing of the constant velocity joint which concerns on the other Example of this invention.

Explanation of symbols

1, 11, 21 Constant velocity joint 2, 12, 22 Outer member 3, 13 Inner member 4, 5, 14, 15, 23 Track groove 6, 16 Torque transmission member (ball)
7, 17 Cage 7a, 17a Spherical surface 7b, 17b Spherical surface 8, 18, 28 Shaft 9, 19, 29 Boots 10, 20, 30 Foamed solid lubricant 24 Tripod member 25 Leg shaft 26 Torque transmission member (spherical roller)
27 Needle

Claims (16)

Rotational torque is transmitted by the engagement between the track groove and the torque transmission member, and the torque transmission member rolls along the track groove and is moved around in the axial direction. A foamed solid lubricant for a universal joint obtained by foaming and curing a mixture containing a lubricating component, a resin component, a curing agent, and a foaming agent,
Foam for universal joints characterized in that tensile strength of the foamed solid lubricant measured in accordance with Japanese Industrial Standard K6400 is 50 kPa or more, elongation is 200% or more, and 40% stress at compression is less than 15 kPa. Solid lubricant. The lubricating component is at least one lubricating component selected from a hydrocarbon-based lubricating oil and a hydrocarbon-based grease;
The resin component is a liquid rubber having a hydroxyl group in the molecule. The liquid rubber has a polymer main chain composed of hydrocarbon, and a hydroxyl group having an amount of hydroxyl value of 25 to 110 mgKOH / g at the end of the main chain. A liquid rubber having
The curing agent is an organic compound having an isocyanate group in the molecule,
The blowing agent is water;
The ratio between the liquid rubber and the curing agent is such that the hydroxyl group contained in the liquid rubber and the isocyanate group contained in the curing agent are in an equivalent ratio of (OH / NCO) = 1 / (1.0 to 2.0). ,
2. The foamed solid lubricant for a universal joint according to claim 1, wherein the mixture includes 40 to 80 wt% of the lubricating component and 5 to 45 wt% of the liquid rubber with respect to the entire mixture.   The liquid rubber is a hydroxyl group-terminated diene polymer having a number average molecular weight of 1000 to 3,500 having a hydroxyl group at the main chain end of a butadiene or isoprene polymer, or a modified hydroxyl group-terminated diene polymer obtained by hydrogenating the diene polymer. The foamed solid lubricant for a universal joint according to claim 2, wherein   The organic compound having an isocyanate group in the molecule is a prepolymer having two or more isocyanate groups in the molecule and a ratio of isocyanate groups of 2.5 to 5.0 NCO%. The foamed solid lubricant for a universal joint according to claim 3.   The foamed solid lubricant for a universal joint according to claim 2 or 3, wherein the organic compound having an isocyanate group in the molecule is an aromatic polyisocyanate.   The foamed solid lubricant for a universal joint according to claim 5, wherein the aromatic polyisocyanate is tolylene diisocyanate. The lubricating component is at least one lubricating component selected from lubricating oil and grease;
The resin component is a urethane prepolymer containing 2 wt% or more and less than 6 wt% of isocyanate groups in the molecule,
The blowing agent is water;
The foamed solid lubricant for a universal joint according to claim 1, wherein the mixture contains 30 to 70% by weight of the lubricating component with respect to the whole mixture, and the open cell ratio after foaming is 50% or more. .   8. The foam for a universal joint according to claim 7, wherein the urethane prepolymer is at least one urethane prepolymer selected from an ester urethane prepolymer, a caprolactone urethane prepolymer, and an ether urethane prepolymer. Solid lubricant.   The ratio of the isocyanate group and the functional group of the curing agent that reacts with the isocyanate group is an equivalent ratio (functional group of the curing agent / NCO) = 1 / (1.1 to 2.5). The foamed solid lubricant for a universal joint according to claim 7 or 8.   The ratio of the hydroxyl group of the water to the functional group of the curing agent is an equivalent ratio (water hydroxyl group / functional group of the curing agent) = 1 / (0.7 to 2.0). The foamed solid lubricant for a universal joint according to claim 8 or 9.   The foamed solid lubricant for a universal joint according to any one of claims 7 to 10, wherein the curing agent is an aromatic polyamino compound.   The foamed solid lubricant for a universal joint according to claim 11, wherein the aromatic polyamino compound is an aromatic polyamino compound having a substituent at a position adjacent to an amino group.   The foamed solid lubricant for a universal joint according to any one of claims 1 to 12, wherein the mixture is filled around a torque transmission member before foaming / curing is completed. A rotational joint is transmitted by the engagement between the track groove and the torque transmission member, and the torque transmission member rolls along the track groove to move in the axial direction.
A universal joint, wherein the foamed solid lubricant for a universal joint according to any one of claims 1 to 12 is sealed around the torque transmission member.   The universal joint according to claim 14, wherein the universal joint is a constant velocity universal joint.   The universal joint according to claim 15, wherein the torque transmitting member is a ball, and the ball is a fixed type of three, six, or eight.

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