JP2010018779A - Coating composition for engine component and engine component using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating composition for engine components, which is effective for preventing attachment and deposition of oil sludge caused by denaturation of engine oil, and an engine component such as an oil ring coated with the same. <P>SOLUTION: The engine component is coated with the coating composition for engine components comprising an alkoxysilyl group, an organopolysiloxane group and a lipophilic group. The engine component is coated with the composition further comprising at least one chosen from a polyfluoroalkyl group and a polyfluoropolyether group. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a coating composition for engine parts and an engine part using the same, and more specifically, a coating composition for engine parts effective for preventing adhesion and accumulation of oil sludge caused by modification of engine lubricating oil and the same. It is related with engine parts, such as an oil ring using.

  In an internal combustion engine, as a long-term operation of the engine is performed, the lubricating oil is heated and exposed to blow-by gas, whereby hydrocarbon unburned products and modified oil additives are mixed in the lubricating oil. . In diesel engines, fine carbon particles are also mixed in the lubricating oil. Such unburned products, modified oil additives, and fine carbon particles are generally referred to as “oil sludge”. However, when oil sludge adheres to and accumulates on engine parts, the parts may be worn out or the passage of lubricating oil may be blocked. Blocking may interfere with the functions of various engine components.

  An oil control ring (two-piece type oil ring) 1 with a coil expander shown in FIG. 1 is composed of a pair of rail portions 2 formed vertically in the axial direction and a web 3 connecting between them, and has an annular shape. Oil ring main body 4 and a coil expander 5 that presses the oil ring main body 4 radially outward. In such a two-piece type oil ring 1, oil sludge may adhere to and accumulate on the outer peripheral surface of the coil expander 5 and the inner peripheral groove portion 6 of the oil ring main body 4 to block the lubricating oil passage. The oil sludge adheres and accumulates in the oil hole 7 and the outer peripheral groove 8 and is highly likely to block the oil hole 7. If the oil hole 7 is blocked, the oil control function is not exerted, and the consumption of the lubricating oil may increase. If oil sludge adheres and accumulates between the pitches of the coil expander 5, not only the passage of the lubricating oil is blocked, but also the stretchability of the coil expander 5 is lost. In particular, when the coil expander 5 is of a low tension specification, the oil sludge adhering to and accumulating between the pitches reduces the force that presses the oil ring body 4 against the inner wall surface of the cylinder, and the two-piece oil ring 1 There is a possibility that the follow-up performance is lowered.

  On the other hand, a steel combination oil control ring (three-piece type oil ring) 10 shown in FIG. 2 includes a pair of annular side rails 11 having a joint and a spacer expander 12 that supports the side rails 11. In the three-piece type oil ring 10, the side rail 11 is pressed with a component force in the radial direction and the axial direction depending on the angle of the ear portion 13 of the spacer expander, and exhibits a sealing function on the cylinder wall surface and the upper and lower surfaces of the ring groove. . In particular, the three-piece oil ring with a reduced axial width, i.e., the h1 dimension, has good followability to the cylinder wall surface and also has a side seal function, so it does not increase oil consumption even at low tension. Friction loss can be reduced. However, even in the three-piece type oil ring 10, oil sludge is likely to adhere and accumulate in the space 15 between the side rail 11 and the flat portion 14 on the outer peripheral side of the ear portion 13 of the spacer expander 12. In particular, when the width is reduced, oil sludge accumulates and the side rail 11 adheres to the spacer expander 12, thereby reducing the followability of the side rail 11 to the cylinder inner peripheral surface and reducing oil consumption. The amount tends to increase.

Conventionally, a liquid repellent treatment has been studied as a method for preventing the adhesion and accumulation of oil sludge to engine parts such as the oil ring described above. By forming an oil-repellent coating on the surface of the engine component, it is intended to prevent oil sludge from adhering to the lubricating oil. As materials used for the oil-repellent treatment, there are many fluorine-based materials such as polytetrafluoroethylene and fluorinated alkylsilane. For example, Patent Document 1 proposes a method of forming a liquid repellent film by a sol-gel method from a metal alkoxide and a fluoroalkyl group-substituted metal alkoxide in which a part of the alkoxyl group is substituted with a fluoroalkyl group. Substances containing fluoroalkyl groups are known to have water and oil repellency, and the presence of this fluoroalkyl group on the surface of the coating film imparts liquid repellency to engine parts, and prevents oil sludge from adhering. It is intended to prevent accumulation.
However, Patent Document 2 describes that the film of Patent Document 1 formed by a sol-gel method using a fluoroalkyl group-substituted metal alkoxide is very thin and is not suitable for practical use. For this reason, Patent Documents 2 and 3 propose a method of increasing the film thickness by promoting polymerization of a fluoroalkyl group-substituted alkoxide before applying a coating solution to a substrate.

  As described above, as a conventional method for preventing the adhesion and accumulation of oil sludge, a method for oil-repellent treatment of the surface of the engine component has been studied. However, in a running engine, the lubricating oil is exposed to high temperatures, and its properties and behavior differ from those at normal temperatures, so the conventional oil-repellent coating provides sufficient adhesion prevention for lubricating oil at high temperatures. It has been found that it cannot be effective. Therefore, oil sludge partially adhered to engine parts under high-temperature operation is further heated under high-speed operation of the engine, and solidifies on the surface of the engine parts, causing parts to wear and piston rings to stick. It becomes. Thus, under the present circumstances, even in operation for a long period of time, a coating composition for engine parts that can prevent the adhesion and accumulation of oil sludge and an engine part using the same have not been obtained.

JP-A-7-246365 JP 10-157013 A JP 2000-27995 JP

  Accordingly, an object of the present invention is to provide a coating composition for an engine component that can prevent oil sludge from adhering to and accumulating on an engine component, particularly, a piston ring sticking, and an engine component using the same, even during long-term engine operation. Is to provide.

  As a result of diligent research in view of the above object, the present inventors have coated the composition containing an oleophilic group on the surface of the engine component to facilitate the adhesion of the lubricant, and the surface of the engine component is always covered with the lubricant. The inventors have found out that the oil sludge can be prevented from adhering and accumulating by making it wet. That is, the first coating composition for engine parts of the present invention is characterized by containing an alkoxysilyl group, an organopolysiloxane group, and a lipophilic group. In the second engine component coating composition of the present invention, the first engine component coating composition further contains at least one of an oil-repellent polyfluoroalkyl group and a polyfluoropolyether group. It is characterized by that. The engine component of the present invention is characterized in that the surface is coated with the above coating composition for engine components.

  Since the first coating composition for engine parts of the present invention contains a lipophilic group, the lubricating oil tends to adhere to the surface of the engine part coated with this, and the surface of the engine part is always wetted with the lubricating oil. Can be maintained. For this reason, in the engine component of the present invention, even if oil sludge is mixed in the lubricating oil, it is easy to flow from the surface of the component together with the lubricating oil. Can maintain the function. On the other hand, the second coating composition for engine parts of the present invention contains a lipophilic group and an oil-repellent group. For this reason, the engine component coated with the second coating composition for engine components of the present invention can usually keep the surface wet with the lubricating oil, and can prevent the oil sludge from adhering and accumulating. Further, when oil sludge partially deposits and adheres or accumulates, oil repellent groups are present on the surface, and therefore oil sludge is easily peeled off from the component surface due to engine vibration or the like. For this reason, accumulation of oil sludge can be prevented for a longer period of time, and a desired function can be exhibited.

Hereinafter, the coating composition for engine parts of the present invention and engine parts using the same will be described in detail.
(1) 1st coating composition for engine parts of this invention The 1st coating composition of this invention contains an alkoxy silyl group, an organopolysiloxane group, and a lipophilic group, It is characterized by the above-mentioned. Here, the lipophilic group is a lipophilic group other than the organopolysiloxane group, and examples thereof include an aliphatic hydrocarbon group having 1 to 30 carbon atoms or a cyclic hydrocarbon group. In the composition, a compound containing all of an alkoxysilyl group, an organopolysiloxane group and a lipophilic group may be used as an active ingredient, and a compound containing one or more of the groups may be mixed and used as an active ingredient. You can also. The active ingredient may be a non-polymerizable compound or a polymer obtained by copolymerizing a polymerizable compound, or a mixture of both can be used.
The polymer is a polymer unit derived from a polymerizable compound having an alkoxysilyl group, a polymer unit derived from a polymerizable compound having an organopolysiloxane group, and a polymer unit derived from a polymerizable compound having a lipophilic group. It is preferable to contain 1 type. Examples of such a mixture of a polymer and a non-polymerizable compound include a non-polymerizable compound having an alkoxysilyl group, a polymerizable compound having an organopolysiloxane group, and a polymerization having a lipophilic group. And a composition obtained by mixing a polymer obtained by copolymerizing a functional compound. However, from the viewpoint of film uniformity and coating processing ease, the coating composition for engine parts of the present invention contains, as an active ingredient, a polymer unit derived from a polymerizable compound having an alkoxysilyl group, an organopolysiloxane group. It is preferable to use a polymer containing all of the polymer units derived from the polymerizable compound having a polymer and the polymer units derived from a polymer having a lipophilic group.

As the polymerizable compound having an alkoxysilyl group, a compound represented by the following formula (a) is preferable.
^{_{CH 2 = C (R 1)}} -C (O) O-Q 1 -Si (R 2) (R 3) (R 4) ··· (a)
Where
R ¹ : hydrogen atom or methyl group,
R ² , R ³ , R ⁴ : alkoxy group,
Q ¹ : a single bond or a divalent linking group.

In the formula (a), R ¹ is a hydrogen atom or a methyl group, and is preferably a methyl group because of excellent oil sludge adhesion and deposition prevention performance.
R ² , R ³ and R ⁴ are alkoxy groups, preferably an alkoxy group having 1 to 3 carbon atoms. R ² , R ³ , and R ⁴ may be the same alkoxy group or different alkoxy groups.
In formula (a), Q ¹ can be appropriately selected as long as it is a single bond or a divalent linking group, but it is obtained by combining a single bond, an alkylene group having 1 to 6 carbon atoms, an amino group, a sulfonyl group, or a combination thereof. It is preferable that it is the bivalent coupling group obtained. Among these, an alkylene group having 1 to 6 carbon atoms is preferable.

Among the compounds represented by the formula (a), it is particularly preferable to use a compound represented by the following formula (a1).
^{_{CH 2 = C (R 1)}} -C (O) O- (CH 2) n-Si (OR 6) 3 (a1)
In formula (a1),
R ¹ : a hydrogen atom or a methyl group,
R ⁶ : an alkyl group having 1 to 3 carbon atoms,
n: An integer from 1 to 6.

As the polymerizable compound having an organopolysiloxane group, a compound represented by the following formula (b) is preferable.
^{_{CH 2 = C (R 1)}} -C (O) O-Q 1 -Y ··· (b)
Where
R ¹ : a hydrogen atom or a methyl group,
Q ¹ : a single bond or a divalent linking group,
Y: An organopolysiloxane group having a number average molecular weight (Mn) of 1000 to 15000.
In formula (b), R ¹ and Q ¹ similar to those in formula (a) are used.
In the formula (b), Y is an organopolysiloxane group having a number average molecular weight (Mn) of 1000 to 15000. Examples of the organopolysiloxane group include groups in which a silicon atom of a repeating unit represented by-(SiO) x- is substituted with a hydrogen atom, an alkyl group, a phenyl group, or the like. Among these, a polydimethylsiloxane group represented by — (Si (CH ₃ ) ₂ O) — is preferable.
Moreover, it is preferable that the terminal of the organopolysiloxane group does not have a polymerizable group. In particular, an alkyl group, an alkoxy group, and a polyether group are preferable, and an alkyl group is more preferable. In addition, the alkyl group, the alkoxy group, and the polyether group may have a substituent.

Among the compounds represented by the formula (b), it is particularly preferable to use a compound represented by the following formula (b1). Among them, a compound having a structure in which the polydimethylsiloxane group has a number average molecular weight of 5000 to 15000 is particularly suitable.
^{_{CH 2 = C (R 1)}} -C (O) O- (CH 2) n- (Si (CH 3) 2 O) m-Si (CH 3) 2 -R 7 (b1)
In formula (b1),
R ¹ : a hydrogen atom or a methyl group,
R ⁷ : an alkyl group,
m: 10 to 400
n: An integer from 1 to 6.

In the formula (b1), R ⁷ is an alkyl group. The group may have a substituent, but does not contain a polymerizable functional group in the group.
In formula (b1), as the substituent of R ^7, a hydroxyl group, a halogen atom, a cyano group, an alkoxy group, ant - proxy group, an alkylthio group, an acyl group, a carboxyl group, a sulfonyl group, an acyloxy group, a sulfonyloxy group, phosphonyl Group, amino group, amide group, alkyl group, aryl group, heterocyclic group, alkoxyacyloxy group and the like. In the formula (b1), examples of the polymerizable functional group excluded from the substituent of R ⁷ include a polymerizable unsaturated group such as a vinyl group, an acryloyl group, and a methacryloyl group, an epoxy group, and an isocyanate group. R ⁷ is preferably an alkyl group having 1 to 5 carbon atoms.

As the polymerizable compound having a lipophilic group, a compound represented by the following formula (c) is preferable.
CH ₂ = C (R ¹ ) —C (O) O—R ⁵ (c)
Where
R ¹ : a hydrogen atom or a methyl group,
R ⁵ : an alkyl group having 1 to 30 carbon atoms.
In Formula (c), R ¹ similar to Formula (a) is used.
In the formula (c), R ⁵ is an alkyl group having 1 to 30 carbon atoms. The group may have a substituent, but does not contain a polymerizable functional group in the group. As the substituent, a hydroxyl group, a halogen atom, a cyano group, an alkoxy group, an aryloxy group, an alkylthio group, an acyl group, an acyl group, a carboxyl group, a sulfonyl group, an acyloxy group, and a sulfonyloxy group within a range not impairing the lipophilicity of R ⁵ Group, phosphonyl group, amino group, amide group, alkyl group, aryl group, heterocyclic group, alkoxyacyloxy group and the like are used. The alkyl group may have either a linear structure or a branched structure, but a linear structure is preferred. As for carbon number of an alkyl group, 10-30 are preferable. Further, the substituent of the alkyl group does not contain a polymerizable unsaturated group such as a vinyl group, an acryloyl group or a methacryloyl group, or a polymerizable functional group such as an epoxy group or an isocyanate group.

Among the compounds represented by the formula (c), it is particularly preferable to use a compound represented by the following formula (c1).
^{_{CH 2 = C (R 1)}} -C (O) O- (CH 2) n-H (c1)
In formula (c1),
R ¹ : a hydrogen atom or a methyl group,
n: An integer of 10-30.

As described above, as the active ingredient of the first engine component coating composition of the present invention, a mixture of a compound having an alkoxysilyl group, a compound having an organopolysiloxane group, and a compound having a lipophilic group is used. It is also possible to use a polymer obtained by copolymerizing a polymerizable compound having an alkoxysilyl group, a polymerizable compound having an organopolysiloxane group, and a polymerizable compound having a lipophilic group.
Here, when the coating (effective) component, that is, the total amount of the above-mentioned compounds is 100, the compound having an alkoxysilyl group is preferably 20% by mass or less, and preferably 1 to 10% by mass. Is more preferable. By adjusting to this range, the stability of the coating composition for engine parts is excellent, and the adhesion of the resulting coating to the substrate is improved.
Moreover, it is preferable that the compound which has an organopolysiloxane group is 5 mass% or more, and it is more preferable that it is 10-30 mass%. By adjusting to this range, the balance of oil repellency and oleophilicity of the resulting coating is improved, and excellent oil sludge adhesion and deposition preventing effects can be exhibited.
The compound having a lipophilic group is preferably 50% by mass or more, and more preferably 60 to 90% by mass. By adjusting to this range, an excellent oil sludge adhesion and accumulation preventing effect can be exhibited.
In addition, a plurality of compounds (polymerization units) can be used for any compound, and in that case, the total amount thereof may be adjusted to be in the above range.

The first coating composition for engine parts of the present invention contains an alkoxysilyl group, an organopolysiloxane group, and a lipophilic group as essential components, but may contain other compounds (polymerized units). The other compound is not particularly limited as long as it is a polymerization unit (E) derived from a compound that can be blended with the essential component or a compound that can be copolymerized with a compound that forms a polymerization unit of the essential component. Examples include structures derived from acrylic acid, methacrylic acid and their ester compounds, epoxy compounds, and the like.
Moreover, as an example of the polymerization unit (E), a polymerization unit derived from a polymerizable dye or the like can be mentioned, and the addition of these improves the visibility of the film. The polymerizable dye is not particularly limited, and examples thereof include polymerizable compounds having a coumarin skeleton, a carbazole skeleton, a fluorocene skeleton, a stilbene skeleton, an anthracene skeleton, a pyrene skeleton, and the like.
The polymerization unit (E) may be a polymerization unit derived from one or more compounds. The content of the polymerization unit (E) varies depending on the type, but when the total amount of coating components is 100, the total polymerization unit (E) content is preferably 50% by mass or less, and 20% by mass. % Or less is more preferable.

In the present invention, when a polymer obtained by copolymerizing a polymerizable compound having an alkoxysilyl group, a polymerizable compound having an organopolysiloxane group, and a polymerizable compound having a lipophilic group is used, the number average molecular weight of the polymer is used. However, it is preferably 2000 to 200,000, more preferably 10,000 to 200,000, and even more preferably 20,000 to 100,000.
The polymerization form of the polymer is not particularly limited and may be any of random copolymerization, block copolymerization, graft copolymerization, and the like, but random copolymerization is preferable.
Moreover, although it does not specifically limit about a manufacturing method, Generally, the method of carrying out addition polymerization based on the unsaturated group in each compound is used. The polymerization can be carried out by appropriately adopting known addition polymerization conditions for unsaturated compounds. The polymerization initiator is not particularly limited, and usual polymerization initiators such as organic peroxides, azo compounds, persulfates can be used.

  At the time of polymerization, in addition to the polymerizable compound and the polymerization initiator, other components such as a polymerization regulator, a polymerization catalyst, a reactive dye, and an antistatic agent may be added as long as the effects of the present invention are not impaired. These components have a total amount of 10% by mass or less, more preferably 5% by mass or less, and more preferably 1% by mass or less when the total amount of coating components is 100. Further preferred.

The coating composition for engine parts of the present invention is preferably prepared directly as a liquid composition by copolymerizing the polymerizable compound in a solvent described later. When the polymerizable compound is a gas raw material such as vinyl chloride, it may be continuously supplied under pressure using a pressure vessel.
The solvent for adjusting the coating composition for engine parts of the present invention is not particularly limited as long as it can dissolve or disperse the polymer, and examples thereof include various organic solvents, water, and mixed solvents thereof.

(2) Second coating composition for engine parts according to the present invention The second coating composition according to the present invention further comprises an oil-repellent polyfluoroalkyl group and a poly-polyalkyl group in addition to the first coating composition for engine parts. It is characterized by containing at least one of fluoropolyether groups. As the compound containing an alkoxysilyl group, an organopolysiloxane group, and a lipophilic group, those similar to the above-mentioned second coating composition for engine parts of the present invention are used.

As the polymerizable compound having at least one of an oil-repellent polyfluoroalkyl group and a polyfluoropolyether group, a compound represented by the following formula (d) is preferable.
^{_{CH 2 = C (R 1)}} -C (O) O-Q 1 -R f (d)
Where
R ¹ : a hydrogen atom or a methyl group,
R ^f : polyfluoroalkyl group or polyfluoropolyether group,
Q ¹ : a single bond or a divalent linking group.
In formula (d), R ¹ and Q ¹ similar to those in formula (a) are used.
In the formula (d), the polyfluoroalkyl group means a partially fluoro-substituted or perfluoro-substituted alkyl group in which two to all of the hydrogen atoms of the alkyl group are substituted with fluorine atoms. The polyfluoroalkyl group represented by the Rf group may have a linear structure or a branched structure. Examples thereof include a partially fluoro-substituted or perfluoro-substituted alkyl group corresponding to an alkyl group having a linear structure such as methyl, ethyl, propyl, butyl, pentyl, hexyl, or a branched structure. Examples of the polyfluoroalkyl group having a branched structure include perfluoro-substituted alkyl groups such as isopropyl group and 3-methylbutyl group.
The polyfluoropolyether group means a group in which an etheric oxygen atom is inserted between one or more carbon-carbon atoms in the polyfluoroalkyl group.

The R ^f group has no problem in performance even if it has 8 or more carbon atoms, but it is more preferable that it has 6 or less carbon atoms in consideration of the influence on the living body and the environment. The R ^f group may have a linear structure or a branched structure, but a linear structure is preferable from the viewpoint of increasing the orientation of the R ^f group. For the same reason, in the case of a branched structure, the branched portion is preferably a structure present at the terminal portion of the R ^f group. The R ^f group is preferably a polyfluoroalkyl group. Further, the R ^f group is preferably a substantially perfluorinated perfluoroalkyl group (R ^F group), and more preferably a linear R ^F group.

Among the compounds represented by the formula (d), it is particularly preferable to use a compound represented by the following formula (d1).
^{_{CH 2 = C (R 1)}} -C (O) O- (CH 2) n-R f (d1)
In formula (d1),
R ¹ : a hydrogen atom or a methyl group,
R ^f : polyfluoroalkyl group,
n: An integer from 1 to 6.

In the second coating composition for engine parts of the present invention, the coating component, that is, the compound having an alkoxysilyl group is preferably 20% by mass or less when the total amount of the charged compounds is 100. It is more preferably 1 to 10% by mass. By adjusting to this range, the stability of the coating composition for engine parts is excellent, and the adhesion of the resulting coating to the substrate is improved.
Moreover, it is preferable that the compound which has an organopolysiloxane group is 5 mass% or more, and it is more preferable that it is 10-30 mass%. By adjusting to this range, the resulting coating film has a good balance between oil repellency and lipophilicity, and can exhibit excellent oil sludge adhesion and deposition preventing effects.
The compound having a lipophilic group is preferably 0.1% by mass to 50% by mass, and more preferably 1% by mass to 20% by mass. By adjusting to this range, an excellent oil sludge adhesion and accumulation preventing effect can be exhibited.
The compound having an oil-repellent polyfluoroalkyl group or polyfluoropolyether group is preferably 20% by mass to 95% by mass, and more preferably 50% by mass to 80% by mass. By adjusting to this range, a more excellent oil sludge peeling effect can be obtained. In addition, a plurality of compounds (polymerization units) can be used for any compound, and in that case, the total amount thereof may be adjusted to be in the above range.

The second engine component coating composition of the present invention comprises an alkoxysilyl group, an organopolysiloxane group, a lipophilic group, and a compound having at least one of an oil repellent polyfluoroalkyl group and a polyfluoropolyether group. However, other compounds (polymerization units) may be included in the same manner as the first engine component coating composition. As other compounds, the same compounds as the first engine component composition are used.
In addition, a polymerizable compound having an alkoxysilyl group, a polymerizable compound having an organopolysiloxane group, a polymerizable compound having a lipophilic group, and a compound having at least one of a polyfluoroalkyl group and a polyfluoropolyether group are copolymerized. When the polymer used is used, the number average molecular weight of the polymer is preferably 2000 to 200,000, more preferably 10,000 to 200,000, and further preferably 20,000 to 100,000. .
The polymerization form of the polymer is not particularly limited and may be any of random copolymerization, block copolymerization, graft copolymerization, and the like, but random copolymerization is preferable.
Moreover, although it does not specifically limit about a manufacturing method, Generally, the method of carrying out addition polymerization based on the unsaturated group in each compound is used. The polymerization can be carried out by appropriately adopting known addition polymerization conditions for unsaturated compounds. The polymerization initiator is not particularly limited, and usual polymerization initiators such as organic peroxides, azo compounds, persulfates can be used.

The coating composition for engine parts of the present invention is preferably prepared directly as a liquid composition by copolymerizing the polymerizable compound in a solvent described later. When the polymerizable compound is a gas raw material such as vinyl chloride, it may be continuously supplied under pressure using a pressure vessel.
As the solvent for preparing the second engine component coating composition of the present invention, the same solvent as the first engine component coating composition is used. However, since the second coating composition for engine parts contains an oil-repellent group, a fluorine-based solvent is preferable, and hydrochlorofluorocarbon (HCFC) and perfluorocarbon (PFC) are preferable. Used.

(3) Engine component of the present invention The engine component that covers the coating composition for an engine component of the present invention includes a cylinder, a piston, a piston ring, and the like. For example, by coating the inner wall surface of the cylinder head or the wall surface of the piston head with the coating composition of the present invention, adhesion of oil sludge or the like to these parts can be prevented. Also, the oil control ring, such as a two-piece oil ring or a three-piece oil ring, is coated with the coating composition for engine parts of the present invention to prevent oil sludge from adhering and accumulating and preventing the oil control ring from sticking. It is effective for.
A method for coating the engine component coating composition of the present invention on the engine component is not particularly limited, but a liquid phase method such as dip coating or spray coating, which is simple and inexpensive, is preferable. Depending on the coating method, the active ingredient concentration in the solution is adjusted so that an appropriate solution viscosity is obtained. For example, when dip coating is performed, the total amount of active ingredients is preferably 0.1 to 10% by mass, and more preferably 1 to 5% by mass of the entire solution.

The engine component of the present invention has a surface coated with the coating composition for the first or second engine component of the present invention, and the contact angle of paraffinic lubricating oil at 200 ° C. by the following method is from 40 degrees to 60 degrees. The following is preferable. The engine component coated with the coating composition for engine components of the present invention and having a contact angle at 200 ° C. in the above range is further excellent in the effect of preventing the adhesion of oil sludge by wetting the component surface with lubricating oil. Moreover, it is preferable that the coating composition for engine parts of this invention is coat | covered, and the sliding angle in 200 degreeC is 3 to 12 degree | times.
The engine component coated with the engine component coating composition of the present invention and having a falling angle at 200 ° C. in the above range further improves the peeling effect when oil sludge partially adheres to the component surface.

(Measurement method of contact angle)
The measurement sample was fixed to an aluminum hot stage provided with a heater, and the temperature of the measurement sample surface was measured with a thermocouple, and adjusted to 200 ± 2 ° C. With a micropipette, 10 μL of paraffinic lubricating oil (lubricating oil for paraffinic raw material “Super Oil N100” manufactured by Nippon Oil Corporation) was dropped onto the measurement sample. At this time, a contact angle was defined as an angle formed between a cut line drawn on the droplet at the contact point of the three phases of the measurement sample, the droplet, and the air, and the surface of the measurement sample, including the droplet. Each measurement sample was measured at 10 locations, and the average value was taken as the contact angle of the sample.

(Measurement method of sliding angle)
The measurement sample was fixed to an aluminum hot stage provided with a heater, and the temperature of the measurement sample surface was measured with a thermocouple, and adjusted to 200 ± 2 ° C. With the measurement sample held horizontally, 30 μL of paraffinic lubricating oil (lubricant for paraffinic raw material “Super Oil N100” manufactured by Nippon Oil Corporation) was dropped onto the surface of the sample with a micropipette. Thereafter, the measurement sample was tilted by 1 °, and the tilt angle when the receding side of the oil droplet started to move was defined as the falling angle. The sample was further tilted after it was allowed to stand for 1 minute every 1 ° tilt, and after confirming that the receding side of the oil droplet did not move. Each measurement sample was measured at five locations, and the average value was taken as the falling angle of the sample.

  EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example, this invention is not limited to these Examples. Note that “%” in the description of the following examples represents “% by mass” unless otherwise specified. In the following examples, the polymerizable compounds ((a), (b), (c), and (d)) containing an alkoxysilyl group, an organopolysiloxane group, a lipophilic group, and an oil repellent group are used. A commercially available reagent having the structure shown in Table 1 was used.

[Adjustment of Example Compositions (Compositions 1 to 7)]
Each monomer, a polymerization solvent, and a polymerization initiator were respectively charged in an airtight container at a blending ratio shown in Table 2, and the reaction was allowed to proceed at 70 ° C. for 26 hours to obtain polymerization compositions 1 to 7. The obtained polymerization composition was diluted with the same solvent as the polymerization solvent so that the content of the polymer would be 1% by mass, thereby preparing compositions 1 to 7. In addition, Wako Pure Chemical Industries Ltd. initiator V-601 was used as a polymerization initiator, and toluene or metaxylene hexafluoride (m-XHF) was used as a solvent.
With respect to the polymerization composition 7, NMR spectra of ¹ H, ¹³ C and ¹⁹ F were measured. The measurement sample was prepared by evaporating the polymerization solvent contained in the sample after the reaction with a vacuum concentrator and then dissolving it in heavy benzene. ^{In the 1} H NMR spectrum, Si—CH ₃ of (b) is around 0.24 ppm, — (CH ₂ ) ₁₆ − of (c) is around 1.35 ppm, and Si—OCH ₃ of (a) is around 3.50 ppm. A peak attributed to protons was observed. In addition, a peak attributed to —COO—CH ₂ — proton common to (a), (b), (c) and (d) was confirmed at around 4.1 ppm. ^{In the 13} C NMR spectrum, Si-CH ₃ of (b) is around 1.3 ppm,-(CH ₂ ) _16- , -CH _2- of (c) is around 30 ppm, and Si-OCH of (a) is around 50 ppm. _3, -CF ₃ near 107~129ppm of (d), -CF ₂ - peaks due to carbon was observed. In addition, a peak attributed to —C (O) — carbon common to (a), (b), (c) and (d) was confirmed around 176 to 177 ppm. Furthermore, in the ¹⁹ F NMR spectrum, peaks due to F of —CF ₃ and —CF ₂ — in (d) were observed at −82 ppm and −114 to −127 ppm, respectively.
[Adjustment of Comparative Example Compositions (Comparative Compositions 1 to 4)]
Similarly to the preparation of the compositions of the examples, each monomer, a polymerization solvent, and a polymerization initiator were respectively charged in a sealed container at the compounding ratio shown in Table 2, and the reaction was allowed to proceed at 70 ° C. for 26 hours. Polymerization compositions 1 to 4 were obtained. The obtained polymerization composition was diluted with the same solvent as the polymerization solvent so that the content of the polymer would be 1% by mass to obtain comparative compositions 1 to 4. In addition, Wako Pure Chemical Industries Ltd. initiator V-601 was used as a polymerization initiator, and toluene or metaxylene hexafluoride (m-XHF) was used as a solvent.

A stainless steel (SUS304) flat plate (Ra 10 nm or less) having an oxide film formed on the surface by heat treatment at 500 ° C. in the atmosphere was used as a coating substrate. Each substrate is immersed in each of the compositions 1 to 7 and the comparative compositions 1 to 4 for 30 seconds, and then placed in an electric furnace and heat-treated at 120 ° C. for 1 hour in the air. A film was formed on the surface to obtain measurement samples (Examples 1 to 7 and Comparative Examples 1 to 4).
Further, a stainless steel (SUS304) flat plate which was only heat-treated at 500 ° C. in the atmosphere and on which no coating film was formed by the coating composition was used as Comparative Example 5.

Table 3 shows the results of measuring the contact angle and the sliding angle at 200 ° C. for each measurement sample by the method described above. Note that an automatic contact angle meter DM500 manufactured by Kyowa Interface Science Co., Ltd. was used for measurement of the contact angle and the sliding angle.
In Comparative Example 5, paraffin-based lubricating oil was dropped on the substrate, but the liquid spread on the substrate and no droplet was formed, so neither the contact angle nor the sliding angle could be measured.

(Oil sludge adhesion test)
In advance, the deteriorated lubricating oil mixed with oil sludge was heated to adjust the oil temperature to 80 ° C. for use in engine operation. The measurement sample was immersed in the deteriorated lubricating oil for 1 minute and taken out, and then placed in an electric furnace set at a furnace temperature of 200 ° C. and heat-treated for 4 minutes. After the immersion in the deteriorated lubricating oil and the heat treatment at 200 ° C. were repeated for a predetermined time, the surface of the measurement sample was observed to evaluate the adhesion state of the oil sludge. Moreover, the state of the surface after immersing in a hydrocarbon type cleaning agent (NS clean manufactured by Japan Energy Co., Ltd.) and irradiating with ultrasonic waves for 5 minutes was observed, and the peeling state of the oil sludge was evaluated. Table 3 shows the results of evaluating the oil sludge adhesion state and the peeling state of each sample. Here, the oil sludge adhering state was represented by the following judgment criteria by obtaining the area ratio of the portion where the oil sludge adheres by image processing, with the area of the entire measurement sample being 100. Further, the oil sludge peeling state was expressed by the following criteria, by determining the area ratio of the oil sludge adhering portion after ultrasonic irradiation, with the area of the oil sludge adhering portion before ultrasonic irradiation being 100.
Adhesion state Almost no adhesion: ◎, over 0%, less than 20%: ○, 20% or more and 90% or less:
Peeling state 0% (100% peeling): ◎, exceeding 0%, less than 5%: ○, 5% or more and 90% or less: Δ, exceeding 90% (almost no peeling): ×

Comparative Example 5 without coating treatment, Comparative Example 1 coated with a composition containing alkoxysilyl groups and polyorganosiloxane groups, Comparative Example 2 coated with a composition containing alkoxysilyl groups and lipophilic groups, alkoxy In Comparative Example 3 in which the composition containing a silyl group and a perfluoroalkyl group was coated, oil sludge adhered to almost the entire surface of the measurement sample. Even after these samples were ultrasonically irradiated in a hydrocarbon-based cleaning agent, the oil sludge hardly peeled off. However, in Comparative Example 3, slight peeling was observed. In Comparative Example 4 in which a composition containing an alkoxysilyl group, a polyorganosiloxane group, and a perfluoroalkyl group was coated, the amount of oil sludge attached was reduced, but the adhesion preventing effect was not sufficient. .
On the other hand, in Examples 1 to 7, the adhesion of oil sludge was very small. In particular, in Examples 1 and 3 to 7 in which polymerized units containing a lipophilic group were blended in an amount of 1% by mass or more, oil sludge was hardly adhered. I was not able to admit. The contact angle of the paraffinic lubricating oil at 200 ° C. in Examples (1 and 3 to 7) that exhibited an excellent oil sludge adhesion preventing effect was in the range of 40 ° to 60 °.

  About Example 1 and Examples 3-7, the immersion in deteriorated lubricating oil and the heat processing at 200 degreeC were repeated further, and the sample whose oil sludge adhesion area is about 20% with respect to the area of the whole measurement sample was produced. As described above, these samples were immersed in a hydrocarbon-based cleaning agent, irradiated with ultrasonic waves, and then the oil sludge peeling state on the surface was observed. As a result, a good oil sludge peeling effect was recognized in any of the measurement samples. In particular, in Examples 1, 5, 6, and 7 in which the falling angle of the paraffinic lubricating oil at 200 ° C. is 11 degrees or less, the attached oil sludge is peeled off almost 100%, and a more excellent oil sludge peeling effect It was confirmed to have

It is sectional drawing which shows an example of the oil control ring with a coil expander. It is sectional drawing which shows an example of a steel combination oil control ring.

1 ... Oil control ring with coil expander 10 ... Steel combination oil control ring

Claims (7)

  A coating composition for engine parts, comprising an alkoxysilyl group, an organopolysiloxane group, and a lipophilic group.   2. The coating composition for engine parts according to claim 1, comprising at least one of a polyfluoroalkyl group and a polyfluoropolyether group. At least a polymerized unit derived from a compound represented by the following formula (a), a polymerized unit derived from a compound represented by the following formula (b), and a polymerized unit derived from a compound represented by the following formula (c) The coating composition for engine parts according to claim 1 or 2, comprising a polymer (1) containing one kind.
^{_{CH 2 = C (R 1)}} -C (O) O-Q 1 -Si (R 2) (R 3) (R 4) ··· (a)
Where
R ^1: a hydrogen atom or a methyl group,
R ² , R ³ , R ⁴ : alkoxy group,
Q ¹ : a single bond or a divalent linking group.
^{_{CH 2 = C (R 1)}} -C (O) O-Q 1 -Y ··· (b)
Where
R ¹ : hydrogen atom or methyl group,
Q ¹ : a single bond or a divalent linking group,
Y: An organopolysiloxane group having a number average molecular weight (Mn) of 1000 to 15000.
^{_{CH 2 = C (R 1)}} -C (O) O-R 5 ··· (c)
Where
R ¹ : hydrogen atom or methyl group,
R ⁵ : an alkyl group having 1 to 30 carbon atoms. The coating composition for an engine part according to claim 3, wherein the polymer (1) further contains a polymer unit derived from a compound represented by the following formula (d).
^{_{CH 2 = C (R 1)}} -C (O) O-Q 1 -R f (d)
Where
R ¹ : hydrogen atom or methyl group,
R ^f : polyfluoroalkyl group or polyfluoropolyether group,
Q ^{1 is a} single bond or a divalent linking group.   An engine component, wherein the coating composition for an engine component according to any one of claims 1 to 4 is coated.   6. The engine component according to claim 5, wherein the contact angle of the paraffinic lubricating oil at 200 ° C. is 40 degrees or more and 60 degrees or less.   The engine component according to claim 5 or 6, wherein the falling angle of the paraffinic lubricating oil at 200 ° C is 3 degrees or more and 12 degrees or less.

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