JP2006028379A - Porous resin oil retainer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a porous resin oil retainer containing a lubricating oil, having high oil content and excellent use efficiency of the lubricating oil and enabling the proper combination of the resin and the lubricating oil according to the use/specification. <P>SOLUTION: The porous resin oil retainer contains a lubricating oil impregnated in a porous resin having a communicating pore ratio of ≥30%, and ≥60% of the impregnated lubricating oil is usable as the lubricating oil. The porous resin has communicating pores produced by forming a resin compounded with a pore-forming material to obtain a formed article, dissolving the pore-forming material and extracting the pore-forming material from the formed article by using a solvent which does not dissolve the resin. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a porous resin oil retaining body having lubricity or a porous resin oil retaining body capable of supplying lubricating oil to a lubrication part.

As one method for improving the friction and wear characteristics of resin materials, a so-called “gunpla” in which a lubricating oil is added to a resin has been known. This method involves melt-kneading resin and lubricating oil and injection molding or extrusion molding of the raw material shape prior to molding by pelletizing. The maximum amount of lubricating oil that can be added is 10% to prevent deterioration of injection moldability. It is about volume%. Since the resin and the lubricating oil are melt-kneaded, the uniformity and oil retention are high, and the lubricating oil does not ooze out to the surface. For this reason, the function as a lubricating oil supply body is not sufficient, and when the resin material is used as a sliding bearing or the like, sufficient lubrication characteristics are obtained in a region where the PV value obtained by multiplying the load (P) and the sliding speed (V) is high. Cannot be obtained.
Conventionally, there are Patent Document 1 to Patent Document 5 that are oil-impregnated resins that have been developed to cope with the above-described problems and that are formed by mixing a resin and a lubricant in advance into a predetermined shape. Patent Document 1 discloses a composition in which ultrahigh molecular weight polyethylene and grease are blended. Since the composition prevents the lubricating oil from flowing with grease, the amount of lubricating oil in the resin can be 50% by volume or more. Further, the amount of lubricating oil oozing out to the surface is larger than that of Gundam.
In Patent Document 2, Patent Document 3 and Patent Document 4, a fibrous oil conducting material is added to the oil-containing resin, and in Patent Document 5, a material in which lubricating oil is retained in porous silica is mixed with a synthetic resin, Is disclosed. These are all intended to continuously supply lubricating oil to the resin surface, and the amount of lubricating oil in the resin is increased to about 20% by the aid of a conductive material and porous silica. Yes.
As another method, Patent Documents 6 and 7 disclose a method of impregnating a lubricating oil into a resin that has been sintered and molded into a predetermined shape. Considering the close-packing and compression in the molding process, the substantial porosity is 30% at the maximum, and this void content is the oil content.

However, in Patent Document 1, a sufficient amount of oil is secured, but since it is a kneading type in which a resin and a lubricant are mixed in advance, the oil retaining property is high and the utilization efficiency of the added lubricating oil is low. Moreover, since there is much quantity of lubricating oil, there exists a problem that mechanical strength is low.
In Patent Document 2, Patent Document 3, Patent Document 4 and Patent Document 5, as described above, the amount of lubricating oil in the resin is increased to about 20% by volume by the conductive material and porous silica, and the mechanical material is added by adding a reinforcing material. Although it is possible to suppress a decrease in mechanical strength, there are problems such as insufficient lubrication amount and slow oozing speed when applied to bearing cages or the like and lubricated only with oil in the resin.
In addition, since the above Patent Documents 1 to 5 are methods for pre-kneading a resin and a lubricant, the combination of the resin and the lubricant is limited and applicable to a wide range of applications. There is a problem that you can not.
On the other hand, Patent Document 6 and Patent Document 7 increase the degree of freedom of the resin-lubricant combination, but the resins that can actually be sintered and molded are limited to ultrahigh molecular weight polyethylene, polyimide resin, and the like. In addition, as described above, the maximum porosity is 30% at the maximum, and when it is applied to bearing cages and lubrication is performed only with the oil in the resin, the amount of lubricating oil is insufficient. There is a problem that it cannot withstand the demand for longer life in recent years.
JP-A-6-41569 Japanese Patent Laid-Open No. 11-166541 JP 2000-71243 A JP 2000-71244 A JP 2002-129183 A Japanese Patent Laid-Open No. 61-6429 JP-A-9-76371

  The present invention has been made to cope with such problems, and in a porous resin oil retaining body containing a lubricating oil, the oil content is high, the use efficiency of the lubricating oil is excellent, and depending on the application and specifications. It is an object of the present invention to provide a porous resin oil retaining body capable of combining a resin and a lubricating oil.

The porous resin oil retaining body of the present invention is a porous resin oil retaining body obtained by impregnating a resin porous body having a communication porosity of 30% or more with a lubricating oil, which is 60% of the total amount of the impregnated lubricating oil. % Or more can be used as a lubricating oil.
The porous resin body is formed by molding a resin containing a pore forming material into a molded body, and then dissolving the pore forming material and using the solvent that does not dissolve the resin from the molded body to the pores. It has the communicating hole obtained by extracting a forming material, It is characterized by the above-mentioned.

Lubricating oil is not kneaded as in the past, but by impregnating the communication holes, the fluidity of the lubricating oil is ensured, and 60% or more of the total amount of impregnated lubricating oil is used as lubricating oil. Be available.
In addition, that it can utilize as lubricating oil means that this lubricating oil can ooze out to the surface of this porous resin oil retaining body, and can provide lubricity to a sliding surface in each use and use conditions.

The porous resin oil retaining body of the present invention is obtained by impregnating a resin porous body having a communication porosity of 30% or more with a lubricating oil, and 60% or more of the total amount of the lubricating oil can be used as the lubricating oil. The oil content and its utilization efficiency are excellent, and lubricity can be imparted for a long time.
In addition, since the molded resin porous body is impregnated with the lubricating oil, the lubricating oil can be arbitrarily selected according to the application and specifications without considering the resin molding conditions.

The porous resin oil retaining body of the present invention is obtained by impregnating a resin porous body having a communication porosity of 30% or more with a lubricating oil, and 60% or more of the total amount of the impregnated lubricating oil is the porous resin oil retaining body. It can ooze out on the body surface and can be used as a lubricating oil on the sliding surface.
The porous resin oil retaining body of the present invention is excellent in the allowable oil content since the communication holes for retaining the lubricating oil have a communication hole ratio of 30% or more. Further, by having a communication hole structure communicating with the surface of the oil retaining body, 60% or more of the total amount of the lubricating oil impregnated can be oozed out, and thus lubricity can be imparted for a long time. In addition, the speed of oozing varies depending on the use and use conditions of the porous resin oil retaining body.
Hereinafter, the communication porosity, the resin constituting the porous resin oil retaining body of the present invention, the pore forming material, the molding method, and the extraction method will be described.

Face-centered cubic lattice and hexagonal close-packed packing are the most densely packed spheres by point contact, and their filling ratio is (volume of sphere ÷ volume of circumscribed cube) ÷ (height of equilateral triangle ÷ base) ÷ (Height of regular tetrahedron ÷ one side) and both are 74%. The porosity defined as (100-filling factor) is 26%.
The above calculation is a case where spheres of the same size are considered. However, when spheres of a plurality of sizes are filled, the filling rate becomes larger than the hexagonal close-packed filling, and the porosity becomes smaller.
Further, when the powdered spherical resin particles are sintered after compression molding, there is no point contact, and the spherical resin particles are deformed and brought into surface contact. For this reason, a filling rate becomes larger than a hexagonal close-packing, and a porosity becomes smaller. For this reason, the porosity of conventional sintered resin moldings is limited to about 20%.

上記、数１において、各符号の意味を以下に示す。
Ｖ；加熱圧縮成形法にて成形された洗浄前成形体の体積
ρ；加熱圧縮成形法にて成形された洗浄前成形体の密度
Ｗ；加熱圧縮成形法にて成形された洗浄前成形体の重量
Ｖ₁；樹脂粉末の体積
ρ₁；樹脂粉末の密度
Ｗ₁；樹脂粉末の重量
Ｖ₂；気孔形成材の体積
ρ₂；気孔形成材の密度
Ｗ₂；気孔形成材の重量
Ｖ₃；洗浄後の多孔体の体積
Ｗ₃；洗浄後の多孔体の重量
Ｖ’₂；洗浄後に多孔体に残存する気孔形成材の体積 The communication porosity in the present invention is the same definition as the above porosity, and refers to the porosity in a state where the pores are continuous. That is, it refers to the ratio of the total volume of pores that are continuous to the resin molded body.
Specifically, the communication porosity was calculated by the method shown in Equation (1) in Equation 1.

In the above Equation 1, the meaning of each symbol is shown below.
V: Volume ρ of the pre-cleaning molded body formed by the heat compression molding method; density W of the pre-cleaning molded body molded by the heat compression molding method; Weight V ₁ ; Volume ρ _{1 of} resin powder; Density W _{1 of} resin powder; Weight V _{2 of} resin powder; Volume ρ _{2 of} pore forming material; Density W _{2 of} pore forming material; Weight V _{3 of} pore forming material; Washing The volume W ₃ of the porous body after; the weight V ′ ₂ of the porous body after cleaning; the volume of the pore forming material remaining in the porous body after cleaning

  In the present invention, a resin porous body having a communication porosity of 30% or more, preferably 30% to 90%, more preferably 30 to 70% is obtained by the production method described below.

The resin porous body that can be used in the present invention is obtained by molding a resin containing a pore-forming material into a molded body, then dissolving the pore-forming material and using a solvent that does not dissolve the resin from the molded body. It is obtained by extracting the forming material. For example, a water-soluble powder B having a melting point Y ° C. higher than X ° C. is blended with a resin A having a molding temperature X ° C., and molded at X ° C. to form a molded body. Is extracted with water to obtain a porous body.
In addition, the manufacturing method of a resin porous body is not restricted to this, The arbitrary methods used as the communicating porosity of 30% or more are employable. For example, there is a method of extracting one of the resins separated into two layers by polymer alloy, such as a spinodal decomposition method, with a solvent.

As resin which can be used for this invention, resin powder and pellets, such as a thermoplastic resin, a thermosetting resin, an elastomer, or rubber | gum, can be used. The particle size and shape of the resin powder and pellets are not particularly limited when melt molding because they are kneaded with the pore forming material at the time of melting. In the case of dry blending and compression molding as it is, an average particle diameter of 1 to 500 μm is preferable.
Examples of the thermoplastic resin or thermosetting resin include polyethylene resins such as low density polyethylene, high density polyethylene, and ultrahigh molecular weight polyethylene, modified polyethylene resins, water-crosslinked polyolefin resins, polyamide resins, aromatic polyamide resins, polystyrene resins, Polypropylene resin, silicone resin, urethane resin, polytetrafluoroethylene resin, chlorotrifluoroethylene resin, tetrafluoroethylene / hexafluoropropylene copolymer resin, tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer resin, vinylidene fluoride resin , Ethylene / tetrafluoroethylene copolymer resin, polyacetal resin, polyethylene terephthalate resin, polybutylene terephthalate resin, polyphenylene ether resin, Recarbonate resin, aliphatic polyketone resin, polyvinylpyrrolidone resin, polyoxazoline resin, polyphenylene sulfide resin, polyethersulfone resin, polyetherimide resin, polyamideimide resin, polyetheretherketone resin, thermoplastic polyimide resin, thermosetting Examples thereof include a functional polyimide resin, an epoxy resin, a phenol resin, an unsaturated polyester resin, and a vinyl ester resin. Moreover, the mixture of 2 or more types of materials chosen from the said synthetic resin, ie, a polymer alloy, etc. can be illustrated.

  Examples of the elastomer or rubber include acrylonitrile butadiene rubber, isoprene rubber, styrene rubber, butadiene rubber, nitrile rubber, chloroprene rubber, butyl rubber, acrylic rubber, silicone rubber, fluorine rubber, ethylene propylene rubber, chlorosulfonated polyethylene rubber, chlorinated Examples thereof include vulcanized rubbers such as polyethylene rubber and epichlorohydrin rubber; and thermoplastic elastomers such as polyurethane elastomer, polyester elastomer, polyamide elastomer, polybutadiene elastomer, and soft nylon elastomer.

The pore-forming material is a substance that has a melting point higher than the molding temperature of the resin and can be extracted by being dissolved from the molded body using a solvent that does not dissolve the resin after being blended with the resin to form a molded body. If you can use it.
The pore-forming material is preferably an inorganic salt compound, an organic salt compound, or a mixture thereof, and particularly preferably a water-soluble substance that facilitates the washing and extraction process. Further, an alkaline substance, preferably a weak alkaline substance that can be used as a rust preventive is preferred. Examples of the weak alkali salt include organic alkali metal salts, organic alkaline earth metal salts, inorganic alkali metal salts, inorganic alkaline earth metal salts, and the like. It is preferable to use an organic alkali metal salt or an organic alkaline earth metal salt because even when the unextracted component falls off, it is relatively soft and hardly damages the rolling surface and the sliding surface. In addition, you may use these metal salts 1 type or in mixture of 2 or more types. In addition, it is preferable to use a water-soluble weak alkali salt because inexpensive water can be used as a cleaning solvent, and waste liquid treatment at the time of pore formation is facilitated.
In order to prevent dissolution of the pore forming material during molding, the pore forming material uses a substance having a melting point higher than the molding temperature of the resin used.
Examples of water-soluble organic alkali metal salts that can be suitably used in the present invention include sodium benzoate (melting point: 430 ° C.), sodium acetate (melting point: 320 ° C.) or sodium sebacate (melting point: 340 ° C.), sodium succinate, and stearic acid. Sodium etc. are mentioned. Sodium benzoate, sodium acetate, or sodium sebacate is particularly preferred because of its high melting point, compatibility with various resins, and high water solubility.
Examples of the inorganic alkali metal salt include potassium carbonate, sodium molybdate, potassium molybdate, and sodium tungstate.

The pore-forming material manages the average particle size according to the use of the porous resin oil retaining body.
The ratio of the pore forming material is 30% by volume to 90% by volume, preferably 40% by volume to 90% by volume, with respect to the total amount including other materials such as resin powder, pore forming material and filler. If the volume is 30% by volume or less, the pores of the porous body are hardly formed into continuous pores.
Moreover, you may mix | blend the filler insoluble in the solvent used for extraction of a pore formation material at the time of a mixing | blending. For example, when the solvent is water, glass fiber, carbon fiber, or the like may be blended for the purpose of improving the mechanical strength of the porous body.

The mixing method of the resin material and the pore forming material is not particularly limited, and a kneading method generally used for mixing the resin such as dry blending and melt kneading can be applied.
Alternatively, a method may be used in which the pore-forming material is dissolved in a liquid solvent to form a transparent solution, and then resin powder is dispersed and mixed in the solution, and then the solvent is removed.
The method of dispersing and mixing is not particularly limited as long as it can be mixed in a liquid, and examples thereof include a ball mill, an ultrasonic disperser, a homogenizer, a juicer mixer, and a Henschel mixer. It is also effective to add a small amount of a surfactant in order to suppress separation of the dispersion. At the time of mixing, the amount of solvent is secured so that the pore forming material is completely dissolved by mixing.
As a method for removing the solvent, methods such as heat evaporation, vacuum evaporation, bubbling with nitrogen gas, dialysis, and freeze-drying can be used. Since the method is easy and the equipment is inexpensive, it is preferable to remove the liquid solvent by heat evaporation.

  Regarding the molding of a mixture in which a pore molding material is blended with a resin, any of compression molding, injection molding, extrusion molding, blow molding, vacuum molding, transfer molding, etc., depending on the shape of the target porous resin oil retaining body, etc. The molding method can be adopted. Moreover, in order to improve workability | operativity before shaping | molding, you may process into a pellet, a prepreg, etc.

Extraction of the pore-forming material from the obtained molded body is performed by washing the molded body with a solvent that dissolves the pore-forming material and does not dissolve the resin.
As the solvent, for example, water and alcohol solvents, ester solvents, ketone solvents, and the like can be used as solvents compatible with water. Among these, it is appropriately selected according to the above conditions depending on the type of resin and pore forming material. These solvents may be used alone or in combination of two or more. It is preferable to use water because of its advantages such as easy waste liquid treatment and low cost.
By performing the extraction treatment, the portion filled with the pore forming material is dissolved, and a porous resin body having pores formed in the dissolved portion is obtained.

The porous resin oil retaining body of the present invention can be obtained by impregnating the above resin porous body with a lubricating oil.
Examples of the lubricating oil to be impregnated include spindle oil, refrigerating machine oil, turbine oil, machine oil, dynamo oil, paraffinic mineral oil, naphthenic mineral oil and other mineral oils, polybutene, polyalphaolefin, alkylbenzene, alkylnaphthalene, and alicyclic compounds. Or other non-hydrocarbon synthetic oils such as natural fats and oils, polyol ester oils, phosphate esters, diester oils, polyglycol oils, silicone oils, polyphenyl ether oils, alkyl diphenyl ether oils, fluorinated oils, etc. Any lubricating oil that is generally used, such as oil, can be used without particular limitation.
In the above lubricating oil, as long as the purpose of the present invention is not impaired, an extreme pressure agent, an antioxidant, a rust inhibitor, a pour point depressant, an ashless dispersant, a metal detergent, an interface Activators, wear modifiers, etc. can be blended. As the antioxidant, phenol, amine, sulfur and the like can be used alone or in combination.
In particular, since it is desired that the lubricating oil supplied from the oil retaining body does not undergo oxidative degradation over a long period of time, it is preferable to incorporate the antioxidant as described above.
The impregnation method may be any method that can impregnate the inside of the porous resin body. The pressure reduction impregnation in which the porous resin is immersed in an impregnation tank filled with a lubricating oil and then impregnated under reduced pressure is preferable. Further, when a high viscosity silicone oil or the like is used, it can be impregnated under pressure. It is good also as a pressure-reduced-pressure impregnation combining these.

Example 1
Ultra high molecular weight polyethylene powder (Miperon XM220 manufactured by Mitsui Chemicals, Inc.) and sodium benzoate powder (reagent manufactured by Wako Pure Chemical Industries, Ltd.) are mixed at a volume ratio of 50:50 in a mixer for 5 minutes to obtain a mixed powder Got. Using this mixed powder, a disk having a diameter of 30 mm and a thickness of t 5 mm was molded by a heat compression molding method (200 ° C. × 30 minutes). This molded product was washed with warm water at 80 ° C. for 10 hours with an ultrasonic cleaner to elute the sodium benzoate powder. Thereafter, it was dried at 100 ° C. for 8 hours to obtain a porous body having a communication porosity of 48%. This porous body is impregnated with synthetic lubricating oil (PAO) (Shinflud 801 manufactured by Nippon Steel Chemical Co., Ltd. (viscosity: 46 mm ² / s (40 ° C))) at 60 ° C to prepare a porous resin oil retaining body for testing. Obtained. The oil content was 45% of the total volume. The oil retaining body was subjected to a bleeding test.

Example 2
Mixed powder of ethylene tetrafluoride resin powder (M15 manufactured by Daikin Industries, Ltd.) and sodium benzoate powder (reagent manufactured by Wako Pure Chemical Industries, Ltd.) at a volume ratio of 50:50 for 5 minutes using a mixer. Got. Using this mixed powder, a disk having a diameter of 30 mm × thickness t 5 mm was formed by a heat compression molding method (350 ° C. × 30 minutes). This molded product was washed with warm water at 80 ° C. for 10 hours with an ultrasonic cleaner to elute the sodium benzoate powder. Thereafter, it was dried at 100 ° C. for 8 hours to obtain a porous body having a communication porosity of 48%. This porous body is impregnated with synthetic hydrocarbon oil (Lucanto HC-20 (viscosity: 155 mm ² / s (40 ° C.)) manufactured by Mitsui Chemicals, Inc.) at 60 ° C. by vacuum impregnation, and a porous resin oil retaining body for testing. Got. The oil content was 44% of the total volume. Using this sample, a oozing test of the impregnated oil was performed.

Example 3
Polyetheretherketone (PEEK) resin powder (150 PF manufactured by Victrex), carbon fiber and sodium benzoate powder (reagent manufactured by Wako Pure Chemical Industries, Ltd.) in a volume ratio of 50:10:40 The mixture was melt kneaded and then pulverized to obtain a mixed powder. Using this mixed powder, a disk having a diameter of 30 mm × thickness t 5 mm was formed by a heat compression molding method (360 ° C. × 30 minutes). This molded product was washed with warm water at 80 ° C. for 10 hours with an ultrasonic cleaner to elute the sodium benzoate powder. Thereafter, it was dried at 100 ° C. for 8 hours to obtain a porous body having a communication porosity of 39%. This porous material is impregnated with synthetic lubricating oil (PAO) (Shinflud 801 manufactured by Nippon Steel Chemical Co., Ltd. (viscosity: 46 mm ² / s (40 ° C))) at 60 ° C to obtain a porous resin oil for testing. Got the body. The oil content was 38% of the total volume. Using this sample, a oozing test of the impregnated oil was performed.

Comparative Example 1
Ultra high molecular weight polyethylene powder (Miperon XM220 manufactured by Mitsui Chemicals), polyethylene wax (Suntite S manufactured by Seiko Chemical Co., Ltd.) and synthetic lubricating oil (PAO) (Shinflud 801 manufactured by Nippon Steel Chemical Co., Ltd., viscosity 46 mm ² / s (40 ° C))) in a volume ratio of 20:15:65 and put into a mold. Diameter of 30 mm x thickness t 5 mm by free sintering method (160 ° C x 30 min) A disk was formed. The oil content after molding was 72% of the total volume. Using this sample, a oozing test of the impregnated oil was performed.

Impregnation oil seepage test:
The disks produced in Example 1, Example 2, Example 3 and Comparative Example 1 were measured with quantitative filter paper No. The amount of impregnated oil transferred to the filter paper was investigated as the amount of oil reduction in the disc, sandwiched between 5C (φ100mm, 2 sheets). The results are shown in FIG. In FIG. 1, the horizontal axis represents elapsed time (time (h)), and the vertical axis represents oil decrease amount (g).
As shown in FIG. 1, in each of the examples, it was possible to exude 70% or more of the initial oil content. However, in Comparative Example 1, although the initial oil content was about twice that of Example 3, the oozing amount of the impregnated oil was about 20% of Example 3. It can be seen that the porous resin oil retaining body of each example has communication holes and can effectively use the impregnated oil.

  Since the porous resin oil retaining body of the present invention is excellent in durability, it can be suitably used for applications requiring a long life such as a rolling bearing and a sliding bearing cage.

It is a figure which shows the oozing-out test result of impregnation oil.

Claims (2)

A porous resin oil retaining body obtained by impregnating a resin porous body having a communication porosity of 30% or more with a lubricating oil,
A porous resin oil retaining body, wherein 60% or more of the total amount of the impregnated lubricating oil can be used as a lubricating oil.   The porous resin body is formed by molding a resin in which a pore forming material is blended into a molded body, and then dissolves the pore forming material and uses the solvent that does not dissolve the resin from the molded body to the pore forming material. The porous resin oil retaining body according to claim 1, wherein the porous resin oil retaining body has a communication hole obtained by extracting the water.

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