JP2008106289A - Method for cleaning sintered compact - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an economical, excellently cleanable, highly safe cleaning method for a sintered compact where there is no surface stain and the ooze of cleaning residual oil after drying, drying temperature is lower than that in a water based cleaning agent, and the process from drying to parts cooling can be performed in a short time. <P>SOLUTION: The method for cleaning a sintered compact comprises: a cleaning stage (A) where a sintered component is contacted with a hydrocarbon based cleaning liquid, so as to be cleaned; a coating stage (B) where it is contacted with a rust preventive solution obtained by uniformly dissolved a rust preventive into an organic solvent in such a manner that the concentration of the rust preventive is controlled to 1 to 10 wt.%, so as to form a rust preventive film on the surface of the sintered component; and a stage of rinse (C) where it is contacted with hydrofluorocarbon and/or hydrofluoroether (HFC/HFE), and the hydrocarbon based cleaning liquid and/or organic solvent stuck to the sintered compact is substituted with the HFC/HFE. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for cleaning a sintered part to which oil components such as cutting oil and rust preventive oil, processing scraps, and the like are attached.

  Sintered parts such as gears used in automobile engines have cleaned and removed oils such as sizing oil, cutting oil, and rust preventive oil remaining on the surface and pores after processing, and particles such as cutting waste and foreign matter It will be assembled later. Sintered parts have innumerable fine holes with a diameter of up to about 100 μm, and have oils or the like permeated therein. It must be thoroughly washed away so that the oil does not ooze to the surface after washing and drying. Conventionally, chlorofluorocarbon solvents such as trifluorotrichloroethane or chlorinated solvents such as 1,1,1-trichloroethane, trichloroethylene, and methylene chloride have been used as cleaning agents. However, trifluorotrichloroethane and 1,1,1-trichloroethane contain chlorine, and their production was prohibited in 1995 as substances that destroy the ozone layer. Trichlorethylene and methylene chloride are highly toxic and, if released, cause air pollution and health problems, so they are strictly regulated by law.

  For this reason, water-based cleaning agents and hydrocarbon-based cleaning agents have been proposed as cleaning agents that replace conventional cleaning agents. When the water-based cleaning agent is used, the cleaned part is usually dried at 100 ° C. or higher, so that the dimensional change due to the thermal expansion of the part is large, and the part cannot be assembled until it cools, so that the workability is poor. Furthermore, since a wastewater treatment facility is required, there is a problem that the cleaning system is large, the facility cost is high, and it takes time to replace the cleaning agent in which dirt has accumulated. Therefore, sintering comprising a step of washing with a perfluorocarbon solvent having 6 or less carbon atoms, a step of washing with a water-soluble detergent after this step, and a step of washing again with a perfluorocarbon solvent having 6 or less carbon atoms. A cleaning method for parts has been proposed (see Patent Document 1). Although the drying property has been improved, the use of water-soluble cleaning agents necessitates a wastewater treatment facility, which increases the cost of the equipment and replaces cleaning agents that have accumulated dirt. The problem of taking time and effort remains.

When a hydrocarbon-based cleaning agent is used, the cleaning residue oil may ooze out on the surface and must be cleaned and removed again. Sintered parts sized with rapeseed oil are immersed and swung with a hydrocarbon cleaner at 60 ° C and then dried with hot air at 55 ° C, so that no residual oil stickiness occurs after drying in a short time. A method for cleaning sintered parts that can be performed has been proposed (see Patent Document 2). However, the rapeseed oil has a kinematic viscosity at 40 ° C. of about 40 × 10 ⁻⁶ m ² / s, whereas the anti-rust oil generally has a kinematic viscosity at 40 ° C. of about 1 × 10 ⁻⁶ m. ^Since it is in the range of ² / s to about 10 × 10 ⁻⁶ m ² / s, the rust preventive oil penetrates deeply into the hole of the sintered part and tends to remain inside the hole during cleaning, and gradually after cleaning. There is a possibility of bleeding.
In addition, a method of cleaning a sintered part with a 2-propanol solution containing ethanolamine and organic phosphate has been proposed (see Patent Document 3). Since 2-propanol has a low flash point of 12 ° C., there is a problem in safety.
Japanese Patent Laid-Open No. 6-146039 JP-A-8-209370 Japanese Patent Laid-Open No. 5-140778

  The present invention solves the above-mentioned drawbacks, is highly safe, dirty cleaning liquid can be regenerated and reused, so there is no need to replace the cleaning liquid, and the drying temperature is lower than that of water-based cleaning agents. It is an object of the present invention to provide a method for cleaning a sintered part having excellent cleaning properties such that the cleaning residue oil does not exude later and cleaning can be performed in a short time.

  As a result of diligent research, the inventors of the present invention cleaned the sintered part with a hydrocarbon-based cleaning liquid, and then contacted the rust preventive solution to coat the sintered metal with the rust preventive, and then hydrofluorocarbon (HFC) ) And / or hydrofluoroether (HFE) (hereinafter collectively referred to as HFC / HFE) rinse agent, it is found that the sintered parts can be washed without drying after washing. The present invention has been completed.

That is, the present invention
(A) A cleaning process for cleaning the sintered parts by bringing them into contact with a hydrocarbon-based cleaning liquid,
(B) Next, a coating process for forming a rust-preventing film on the surface of the sintered part by bringing it into contact with a rust-preventing agent solution obtained by uniformly dissolving the rust-preventing agent in an organic solvent so that the concentration becomes 1 to 10% by weight. And (C) a rinsing step in which the hydrocarbon-based cleaning liquid and / or the organic solvent adhering to the sintered part by contacting with the hydrofluorocarbon and / or hydrofluoroether (HFC / HFE) is replaced with the HFC / HFE. This is a method for cleaning sintered parts.

The hydrocarbon-based cleaning liquid preferably has an initial boiling point of 130 ° C. or higher and an end point of 350 ° C. or lower in distillation properties.
Moreover, it is preferable that a rust preventive agent is a thing which does not melt | dissolve in HFC or HFE.
Furthermore, it is preferable that the boiling points of HFC and HFE are both 30 to 100 ° C.

  In the cleaning method of the present invention, after performing sufficient cleaning up to the inside of the fine holes of the sintered part, the rust preventive film replaces the hydrocarbon-based cleaning liquid and covers the inner surface of the fine holes. There is no exudation of washing residue oil. Moreover, since it processes with a rinse agent (HFC / HFE) after coating | cover, it can dry at temperature lower than the case where an aqueous cleaning agent is used. As a result, the cooling time until assembly after drying can be shortened. Moreover, the hydrocarbon-based cleaning liquid and the rinsing agent HFC / HFE that have been used and fouled can be reused with their purity recovered by distillation or the like. For this reason, the waste water treatment facility which occupies a large area like the water-based cleaning liquid is not required, and a comprehensive and economical cleaning system can be constructed. Therefore, the cleaning method of the present invention exhibits a special effect excellent in cleaning performance and economy.

The cleaning method of the present invention includes a cleaning process in which a sintered part is cleaned in contact with a hydrocarbon-based cleaning liquid, a coating process in which a rust preventive film is formed in contact with a rust inhibitor solution, and a contact with HFC / HFE. A rinsing step for rinsing is included.
In the cleaning method of the present invention, the sintered part is cleaned in contact with the hydrocarbon-based cleaning liquid in the cleaning process. Specific examples of the cleaning method include jet cleaning in which a hydrocarbon-based cleaning liquid is sprayed onto a sintered part for cleaning, and immersion cleaning in which a sintered part is immersed in a hydrocarbon-based cleaning liquid for cleaning. Immersion cleaning is more preferable, equipment is relatively simple, and reliable cleaning is expected.

  The hydrocarbon-based cleaning liquid preferably has an initial boiling point of 130 ° C. or higher and an end point of 350 ° C. or lower, more preferably 150 ° C. or higher and 330 ° C. or lower, more preferably 170 ° C. or higher, in distillation properties. More preferably, it is 310 degrees C or less. A hydrocarbon-based cleaning liquid having an initial boiling point of less than 130 ° C. has a flash point lower than room temperature, which is not preferable for safety. In addition, hydrocarbon-based cleaning liquids whose end point exceeds 350 ° C. are not preferable because the viscosity is high, and cleaning of details such as the inside of pores is insufficient, and hydrocarbon-based cleaning liquids whose end point exceeds 350 ° C. This is not preferable because it is difficult to distill and separate a soil component having low properties and reuse the cleaning liquid.

  Examples of the hydrocarbon-based cleaning liquid include cleaning liquids described in JP-A No. 2003-176498 (saturated aliphatic (paraffinic) hydrocarbons having 9 to 12 carbon atoms, monohydric alcohols having 5 to 10 carbon atoms, and carbon numbers). A cleaning liquid described in JP 2006-249114 A (consisting of a saturated aliphatic hydrocarbon having an initial boiling point of 200 ° C. or more and an end point of 350 ° C. or less and an acetate ester), NS Clean (registered trademark; cleaning agent mainly containing saturated aliphatic hydrocarbons), EM Clean (registered trademark; cleaning agent mainly containing aromatic hydrocarbons), etc., commercially available from Japan Energy Co., Ltd. Can be used.

In order to enhance the cleaning effect in the cleaning process, it is more preferable to combine physical forces such as stirring, rocking, jet, ultrasonic wave, air bubbling and the like simultaneously with jet cleaning or immersion cleaning. When using an ultrasonic wave, it is preferable to perform on the conditions of an oscillation frequency of 20 to 100 kHz and an oscillation output of 10 to 200 W per 1 L of cleaning liquid, for example. In the air bubbling, clean air is pressurized to 0.05 to 10 kg / cm ² G with a compressor or the like, and is discharged from the air diffuser at the bottom of the tank to cause interfacial flow. What is necessary is just to set washing | cleaning temperature suitably in the optimal temperature for removing stain | pollution | contamination, specifically within the range of 20-130 degreeC. Moreover, you may implement washing | cleaning by spraying, such as a shower, after immersion washing.
In addition, the particles that do not dissolve in the hydrocarbon-based cleaning liquid from the sintered parts can be cleaned after being previously cleaned and removed with a cleaning agent for particle removal. As the particle removing cleaning agent, the cleaning agent described in Japanese Patent No. 3160854 can be used.

  Further, in the cleaning process, the cleaning liquid is contaminated by dirt carried along with the components, and gradually loses its cleaning ability. Therefore, it is necessary to replace the cleaning liquid when the degree of contamination of the cleaning liquid due to dirt increases to some extent. Here, the degree of contamination means the amount of dirt mixed in the cleaning liquid, and is expressed by, for example, the amount of a substance remaining without volatilization at a temperature at which the cleaning liquid volatilizes, that is, a nonvolatile content. Since the hydrocarbon-based cleaning liquid used in the present invention can be recycled, the amount of waste can be reduced and the running cost can be reduced. As a method for regenerating the hydrocarbon-based cleaning liquid, a known method can be used. For example, the cleaning liquid can be separated from dirt by distillation and recycled. Regeneration by distillation may be performed by distilling and regenerating the entire amount of the cleaning solution in the washing tank when washing is not performed. It doesn't matter. It is efficient and preferable to always extract a part of the liquid from the washing tank, recycle it by distillation, and return the regenerated washing liquid to the washing tank. It is preferable to circulate the washing liquid, and the sintered parts can always be washed with a cleaning liquid with a low degree of contamination. .

The washing | cleaning method of this invention has a coating process which contacts a sintered component with a rust inhibitor solution and forms a rust prevention film after a washing | cleaning process. The rust inhibitor solution used in the coating process is prepared by dissolving a rust inhibitor having a rust prevention function in an organic solvent. The rust preventive is preferably dissolved in an organic solvent and not dissolved in HFC / HFE, and any known rust preventive can be used. Examples of such rust preventives include carboxylic acids, carboxylates, sulfonates, esters, amines, amides, phosphoric acids, phosphates, alcohols, waxes, silicone oils, and derivatives thereof. Specifically, caprylic acid, caproic acid, octanoic acid, 2-ethylhexanoic acid, nonanoic acid, decanoic acid, undecanoic acid, lauric acid, myristic acid, valmitic acid, stearic acid, behenic acid, lanolinic acid, oleic acid, linoleic acid Acid, linolenic acid, salicylic acid, phenylstearic acid, ethylphenylstearic acid, dodecylphenylstearic acid, benzoic acid, butylbenzoic acid, p-methylbenzoic acid, p-isopropylbenzoic acid, pn-dodecyloxybenzoic acid, α -Hydroxypalmitic acid, naphthenic acid, hexanedicarboxylic acid, octane Carboxylic acid, nonanedicarboxylic acid, decanedicarboxylic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, adipic acid, sebacic acid, 10-undecenoic acid, cis-9-octadecenoic acid, cis-11-docosenoic acid, pimelic acid, suberic acid, Azelaic acid, Na-benzoate, K-oleate, Na-p-tertiary butyl benzoate, Zn-4-ethyloctanoate, Zn-laurate, Zn-naphthenate, Mg-naphthenate, Ba-phenyl stearate, Ca-naphthenate Al-naphthenate, Fe-naphthenate, Pb-naphthenate, Ba-stearate, Ca-stearate, Mg-stearate, Al-stearate, Ba-dinonyl naphthenate, Ca-dinonyl naphthenate, Zn-dinonyl naphthe Nate, Pb-dinonyl naphthenate, K-dinonyl naphthenate, duomine T diolate, ammonium stearate, n-dodecyl ammonium stearate, n-octadecyl ammonium stearate, cyclohexyl ammonium stearate, ammonium benzoate, ammonium phthalate, ammonium Palmitate, ammonium oleate, diisopropylammonium benzoate, cyclohexylamine benzoate, dicyclohexylamine benzoate, dicyclohexylammonium cyclohexanecarboxylate, diethanolamine oleate, diethanolamine benzoate, oleoylsarcosine, Ba-petroleum sulfonate, Ca-petroleum sulfonate, Mg-petroleum Sulfonate, Na- Oil sulfonate, Ba-synthetic sulfonate, Ca-synthetic sulfonate, Na-synthetic sulfonate, Na-dinonylnaphthalene sulfonate, Ba-dinonylnaphthalene sulfonate, Ca-dinonylnaphthalene sulfonate, triethanolamine dinonylnaphthalene sulfonate, ethyl stearate , Α-monopalmitin, glycerol monooleate, glycerol dioleate, sorbitan trioleate, sorbitan monooleate, sorbitan monolaurate, sorbitan dilaurate, sorbitan monopalmetate, sorbitan monocaprylate, sorbitan monomyristate, sorbitan monolinatoate, Sorbitan monolinolenate, pentaerythritol monooleate, pentaerythritol trioleate, pentaerythritol Toisostearate, tetrapropenyl succinate, octyl oleyl malate, mono-n-dodecylamine, mono-n-hexadecylamine, mono-n-octadecylamine, di-n-dodecylamine, di-n-octadecylamine, Octadecenylamine, cyclohexylamine, triethanolamine, N-dodecylpropylenediamine, N-palmitylpropylenediamine, N-cyclohexylpropylenediamine, N-dodecylethylenediamine, N-palmitylethylenediamine, N-cyclohexylethylenediamine, N-dodecyl Butylene diamine, N-palmityl butylene diamine, N-cyclohexyl butylene diamine, 3-methyl-5-pyrazolone, dicyclohexylammonium nitrate, benzotriazole Tolyltriazole, imidazole, benzimidazole, indole, 4-methylbenzotriazole, 5-methylbenzotriazole, aminotetrazole, tri-p-cresyl phosphate, cetylmethyl acid phosphate, dibutyl azide phosphate, phosphite, phosphophyllite, ammonium Phosphate, Na-phosphate, Ca-phosphate, K-pyrophosphate, Na-pyrophosphate, K-tripolyphosphate, Na-tripolyphosphate, K-tetrapolyphosphate, Na-tetrapolyphosphate, K-hexapolyphosphate, Na- Hexapolyphosphate, K-hexametaphosphate, Na-hexametaphosphate, eicosyl alcohol, 4-cyclohexylcyclohexa Lumpur, p- cyclohexyl phenol, polystyrene, polyethylene, lanolin, petrolatum and the like. More preferably, stearic acid, oleic acid, duomine T dioleate, diethanolamine benzoate, Na-dinonylnaphthalene sulfonate, sorbitan monooleate, pentaerythritol monooleate, benzotriazole, tolyltriazole, and derivatives thereof are mentioned. .
Moreover, the commercially available rust preventive oil and rust preventive oil containing a well-known rust preventive agent can also be used.

  The organic solvent, which is another component of the rust inhibitor solution used in the coating process, preferably has an initial boiling point of 130 ° C or higher and an end point of 350 ° C or lower. An organic solvent having a boiling point of less than 130 ° C. is generally not preferable for safety because its flash point is lower than room temperature, and an organic solvent having a boiling point of more than 350 ° C. has a high viscosity, so that HFC / HFE in the rinsing step is high. This is not preferable because the efficiency of replacement with is reduced. Moreover, if a boiling point exists in the said range, isolation | separation with HFC / HFE used at a rinse process can also be performed easily.

  As long as the organic solvent satisfies the above requirements, the hydrocarbon solvent, petroleum solvent, alcohol solvent, ether solvent, ester solvent, glycol ether solvent, ketone solvent, terpene solvent, etc. However, hydrocarbon solvents such as saturated aliphatic (paraffinic) hydrocarbons that are less susceptible to changes in physical properties in the working environment, such as saturated aliphatic (paraffinic) hydrocarbons, are preferred, such as high oxidation stability and low hygroscopicity. . The hydrocarbon solvent used in the cleaning process can be different from the hydrocarbon solvent used in the cleaning process. However, the hydrocarbon cleaning liquid used in the cleaning process is easy because liquid management is easy in the entire cleaning process. It is preferable to use the same. Therefore, as an organic solvent, specifically, a cleaning liquid described in JP-A No. 2003-176498 (saturated aliphatic (paraffinic) hydrocarbon having 9 to 12 carbon atoms, monohydric alcohol having 5 to 10 carbon atoms, and And a cleaning liquid described in JP-A-2006-249114 (consisting of a saturated aliphatic hydrocarbon having an initial boiling point of 200 ° C. or higher and an end point of 350 ° C. or lower and an acetate ester). NS Clean (registered trademark; detergent based on saturated aliphatic hydrocarbons) and EM Clean (registered trademark; detergent based on aromatic hydrocarbons) commercially available from Japan Energy Co., Ltd. Etc.

  In the present invention, a rust inhibitor solution having a rust inhibitor concentration of 1 to 10% by weight is used. The rust inhibitor concentration is preferably 1 to 5% by weight. When the concentration of the rust inhibitor is less than 1% by weight, the defective portion that is not covered with the rust preventive film remains on the inner surface of the hole, and the oil that has penetrated deeply into the hole even after cleaning Since it exudes from a defective part, it is not preferable. On the other hand, if the concentration exceeds 10% by weight, the number of rust preventives that are not effectively used for coating increases and is wasted, and the surface of the sintered parts is contaminated with excessive rust preventives, which hinders assembly. This is not preferable because there are some cases.

  In the coating process, the method for forming the rust-preventing film by bringing the sintered part into contact with the rust-preventing agent solution is not particularly limited, and known methods such as spraying and dipping can be used. In order to infiltrate the anticorrosive agent in detail, it is effective to combine physical forces such as stirring, shaking, and ultrasonic waves at the same time.

  In the cleaning method of the present invention, after the coating process, the sintered part is brought into contact with HFC / HFE in the rinsing process, and the hydrocarbon solvent and organic solvent adhering to the part are replaced with HFC / HFE. The boiling point of HFC / HFE used in the rinsing process is preferably 30 to 100 ° C., considering the ease of handling, the drying property, and the cooling time until the dried sintered parts can be assembled, the boiling point is 40 to 80 ° C. Is more preferable. Since HFC / HFE having a boiling point of less than 30 ° C. is too volatile, it has a large evaporation loss at room temperature, which is not preferable. HFC / HFE having a boiling point exceeding 100 ° C. is not preferable because the drying temperature is as high as or higher than that of an aqueous cleaning agent, the dimensional change due to thermal expansion is large, the parts cannot be assembled until cooled, and workability is poor. Moreover, in HFC / HFE, it is preferable that it is compatible with the hydrocarbon solvent and the organic solvent used in the washing process and the coating process, and not compatible with the rust preventive agent. Examples of such hydrofluorocarbon (HFC) include 1,1,1,3,3-pentafluorobutane (boiling point 40 ° C.), 2,3-hydroxydecafluoropentane (boiling point 55 ° C.), and the like. Examples of hydrofluoroether (HFE) include 1,2,2,2-tetrafluoroethyl-heptafluoropropyl ether (boiling point 40 ° C.), 1,1,2,2-tetrafluoroethyl-2,2,2 -Trifluoroethyl ether (boiling point 56 ° C.), nonafluorobutyl methyl ether (boiling point 61 ° C.), nonafluorobutyl ethyl ether (boiling point 76 ° C.) and the like. These may be used alone or in combination of two or more.

  In the rinsing step, the sintered part is brought into contact with HFC / HFE in order to remove the organic solvent and easily dry without damaging the rust preventive film formed on the sintered part. The method is not particularly limited, and a known method can be used. For example, a method of immersing a sintered part with a rust inhibitor solution attached to a tank filled with HFC / HFE, a method of injecting a large amount of HFC / HFE onto the sintered part, and the like can be mentioned. By doing so, the organic solvent in the rust inhibitor solution is replaced with HFC / HFE, and a sintered part covered with the rust preventive film is obtained. In order to enhance the effect during immersion in HFC / HFE or HFC / HFE injection, it is more preferable to combine physical forces such as stirring, rocking, jet flow, ultrasonic waves, air bubbling and the like. Further, in the immersion, after immersion for a certain time, the sintered part is taken out, or HFC / HFE is discharged, and the liquid adhering to the sintered part is flowed down or removed by centrifugation, and then immersed in HFC / HFE again. It is also effective to repeat this several times. This method can also be applied to injection. After injection for a certain period of time, the injection is stopped and the liquid adhering to the sintered part is removed, and then HFC / HFE is again injected onto the sintered part.

In addition, the contact method with HFC / HFE is not limited to the liquid phase, but by placing the sintered component in the HFC / HFE vapor phase and condensing the HFC / HFE vapor on the component surface, The organic solvent adhering to the surface can be replaced with HFC / HFE. In this case, in order to increase the degree of condensation of HFC / HFE vapor on the surface of the component, the greater the temperature difference between the sintered component to be contacted and the HFC / HFE vapor, the greater the replacement effect. The HFC / HFE condensed on the surface of the part forms a mixed solution with the organic solvent of the rust preventive solution adhering to the sintered part. Before soaking in the HFC / HFE rinse solution, removing the mixed solution condensed on the surface using a well-known method such as allowing the sintered parts to stand or suspend (suspending) greatly reduces the progress of dirt in the immersion bath. be able to. It is also possible to rinse by this vapor phase treatment without immersing, but if you want to rinse thoroughly, it is preferable to rinse by immersing and then finish with clean HFC / HFE steam Is preferred.
HFC / HFE used in the rinsing process has a boiling point of 30 to 100 ° C. and high volatility, so that it can be quickly evaporated and the sintered parts can be dried quickly.

  HFC / HFE used in the rinsing process dissolves the organic solvent brought in from the coating process and gradually increases its concentration. However, HFC / HFE can be used repeatedly by separating it from the organic solvent. Is. A method for separating HFC / HFE from an organic solvent or the like is not particularly limited, and a known method such as a distillation separation method can be used.

  In the cleaning method of the present invention, a sintered part to be cleaned is a metal such as iron, copper, nickel, chromium, tungsten, molybdenum, or a powder of an alloy such as stainless steel, which is solidified and molded. Sintered at a temperature at which the powder does not melt, and the resulting powder is a stuck part. Since sintered parts are manufactured by such a method, the sintered parts have excellent various characteristics as shown in the following (1) to (5), and are sintered machine parts and sintered oil-impregnated bearings. Or as a sintered filter, it is widely used not only for the gear used for the engine of a motor vehicle but for machines of every field, such as transport machinery, industrial machinery, and electric machinery.

(1) Since the metal powder is put into a mold and pressed, the mold can be made with a rather complicated shape. It is used as a complex shape part and a multifunctional part of various devices including automobile parts.
(2) Since various metal powders can be mixed in any proportion, iron-based iron, carbon, copper, nickel, phosphorus, molybdenum, manganese, etc., copper-based, such as bronze and brass, and stainless steel Can be used according to the purpose, and can be incorporated into various devices as oil-impregnated bearings and machine parts. For example, powders other than metals such as various metals and ceramics can be mixed with iron powder, and sintered parts with improved friction and wear can be made, such as current collecting plates for Shinkansen pantographs. .

(3) Since the mold is used to make the shape, a large amount of high-precision products can be made, which is suitable for applications that require many parts such as automobiles and home appliances.
(4) Since the metal powder is pressed and hardened and baked, there are gaps called pores between the stuck powders, and oil (lubricating oil) can be put into this. This representative part is an “oil-impregnated bearing”, which does not require oil supply, and is used as a bearing for motors such as hard disks and CDs from washing machine and air conditioning fans.
(5) The size of the “porosity” can be controlled by adjusting the size of the metal powder, and this can be applied to make a “filter”.

EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited by these Examples.
(Sintered part test piece)
The iron-based sintered part was cut to prepare a test piece for cleaning test (outer diameter 82 mm, inner diameter 34 mm, thickness 21 mm). Cutting oil, rust preventive oil, cutting scraps, dust, and the like attached during processing were attached to the test piece. Using the test piece of this sintered part, a cleaning test comprising cleaning with a hydrocarbon cleaning solution, film formation with a rust preventive solution, and / or rinsing with HFC / HFE, etc. is shown in the following examples and comparative examples. The method for cleaning a sintered part of the present invention was evaluated.

(Example 1)
The following cleaning to rinsing steps were performed to clean the sintered part test piece.
Cleaning step: NS100R (hydrocarbon cleaning liquid having a boiling point of 166 to 176 ° C., manufactured by Japan Energy) as a hydrocarbon cleaning liquid is filled in a cleaning tank of an ultrasonic cleaner (HONDA W-113, manufactured by Honda Electronics Co., Ltd.) and sintered. Part test pieces were immersed. And it wash | cleaned for 60 second at 30 degreeC, irradiating an ultrasonic wave with the frequency of 28 kHz.
Coating step: A rust inhibitor solution P obtained by dissolving in NS100R was prepared so that the rust inhibitor concentration of JOMO Evaporation P-950 (manufactured by Japan Energy) was 1.5% by weight. The sintered part test piece that has undergone the cleaning process is taken out from the cleaning tank and immersed in a coating tank filled with the antirust solution P for 20 seconds at 20 ° C., and a coating of the anticorrosive agent is formed on the metal surface of the test piece. A coating was formed.
Rinsing step: Although different from that used in the cleaning step, 1,1,2,2-tetrafluoroethyl is used as a rinsing agent in the cleaning tank of the same type of ultrasonic cleaner (HONDA W-113). Filled with -2,2,2-trifluoroethyl ether (HFE-1). Next, the test piece coated in the coating step was immersed for 20 seconds at 47 ° C. while irradiating ultrasonic waves at a frequency of 45 kHz, and the solvent (NS100R) of the rust inhibitor solution P adhering to the test piece was removed. Dissolved and replaced with HFE-1.

Then, the test piece was taken out from the washing tank of the ultrasonic cleaner used for rinsing and left at room temperature for 5 minutes to dry and remove HFE-1.
The cleanability of the test piece thus obtained was (1) dried stains and adhered particles (hereinafter referred to as surface contamination) on the surface of the sintered part and (2) exudation of residual oil from the sintered part (hereinafter referred to as exudation). These two points were evaluated according to the following criteria.
(1) Surface contamination: The surface of the test piece is visually observed and the amount of dry spots and adhered particles is less than that of a standard test piece obtained by washing the test piece with a 60 ° C. aqueous detergent and then drying it with hot air at 100 ° C. The case was marked with ◯, and the case with many was marked with ×.
(2) Exudation: Oil on the lower surface of the test piece after standing for 3 hours on a filter paper with the test piece lying sideways (with the disk-shaped radial direction horizontal) in an atmosphere of normal pressure and 40 ° C. The presence or absence of oil oozing was visually observed, and the case where there was no oil oozing was judged as ◯, and the case where oil oozing out was judged as x.
The evaluation results are shown in Table 1. In the following examples and comparative examples, the washability was similarly evaluated, and the results are shown in Table 1. Table 1 also shows the main operating conditions of the washing and rinsing steps of the examples and comparative examples.

(Example 2)
In the rinsing step, it was carried out in the same manner as in Example 1 except that it was allowed to stand in the vapor phase of HFE-1 for 20 seconds each before and after being immersed in the HFE-1 rinsing tank.

(Example 3)
In the coating process, it carried out like Example 2 except having changed the rust inhibitor density | concentration of the rust inhibitor solution P into 2.4 weight%.

Example 4
In the coating process, the rust inhibitor solution P is changed to the rust inhibitor solution Q prepared by dissolving in NS100R so that the rust inhibitor concentration of JOMO Evaproof P-3 (manufactured by Japan Energy) is 2.4% by weight. The same procedure as in Example 3 was performed except that.

(Example 5)
In the coating process, the rust inhibitor solution P is dissolved in NS100R so that the concentration of the oil-soluble rust and corrosion inhibitor BT-L (manufactured by Sanwa Kasei) is 2.4% by weight. The same operation as in Example 3 was carried out except that the change was made.

(Example 6)
NS220 (hydrocarbon cleaning liquid with a boiling point of 209 ° C, manufactured by Japan Energy) is used as the hydrocarbon-based cleaning liquid in the cleaning process, and the concentration of the oil-soluble anticorrosive agent BT-L (manufactured by Sanwa Kasei) is 2.4 wt. % Of the rust inhibitor solution S prepared by dissolving in NS220, using nonafluorobutyl methyl ether (HFE-2) as the hydrofluoroether in the rinsing step, and the immersion temperature in the rinsing step is 52 ° C. This was carried out in the same manner as in Example 1 except that the change was made.

(Example 7)
In the rinsing step, the same procedure as in Example 6 was performed, except that the sample was allowed to stand in the vapor phase of HFE-2 for 20 seconds before and after being immersed in the HFE-2 rinse tank.

(Comparative Example 1)
It implemented on the same conditions as Example 1 except not having performed the coating process.

(Comparative Example 2)
It implemented on the same conditions as Example 2 except not having performed the coating process.

(Comparative Example 3)
It implemented on the same conditions as Example 2 except having changed the rust inhibitor concentration of the rust inhibitor solution P of the coating process into 0.5 weight%.

(Comparative Example 4)
It implemented on the same conditions as Example 2 except having changed the rust inhibitor density | concentration of the rust inhibitor solution P of the coating process into 15 weight%.

(Comparative Example 5)
It implemented on the same conditions as Example 6 except not having performed the coating process.

(Comparative Example 6)
It implemented on the same conditions as Example 7 except not having performed the coating process.

(Comparative Example 7)
The cleaning process was performed under the same conditions as in Example 6 except that the cleaning temperature was changed to 60 ° C. and the coating process was not performed.

(Comparative Example 8)
The cleaning process was performed under the same conditions as in Example 7 except that the cleaning temperature was changed to 60 ° C. and the coating process was not performed.

Claims (4)

(A) A cleaning process for cleaning the sintered parts by bringing them into contact with a hydrocarbon-based cleaning liquid,
(B) Next, a coating process for forming a rust-preventing film on the surface of the sintered part by bringing it into contact with a rust-preventing agent solution obtained by uniformly dissolving the rust-preventing agent in an organic solvent so that the concentration becomes 1 to 10% by weight. And (C) a rinsing step in which the hydrocarbon-based cleaning liquid and / or the organic solvent adhering to the sintered part by contacting with the hydrofluorocarbon and / or hydrofluoroether is then replaced with the hydrofluorocarbon and / or hydrofluoroether. A method for cleaning a sintered part.   The method for cleaning sintered parts according to claim 1, wherein the hydrocarbon-based cleaning liquid has a distillation property of an initial boiling point of 130 ° C or higher and an end point of 350 ° C or lower.   The method for cleaning a sintered part according to claim 1 or 2, wherein the rust preventive agent does not dissolve in hydrofluorocarbon or hydrofluoroether.   The boiling point of hydrofluorocarbon and hydrofluoroether are both 30-100 degreeC, The washing | cleaning method of the sintered components in any one of Claims 1-3.