KR20200145707A - Solid Lubricating Coating Composition for silk printing engine pistons - Google Patents

Abstract

Disclosed is a solid lubricating coating composition applied to an engine piston of a vehicle. The solid lubricating coating composition for an engine piston of a vehicle comprises: at least one binder selected from the group consisting of a phenol resin, an epoxy resin, and a polyamide imide resin; a solid lubricant; an additive; and a solvent.

Description

Solid Lubricating Coating Composition for silk printing engine pistons TECHNICAL FIELD

The present invention relates to a solid lubricant coating composition for engine pistons, and more particularly, to a solid lubricant coating composition for engine piston silk printing for improving properties of high lubricity, high heat resistance, and abrasion resistance by being coated on an engine piston.

Automobile engines are representative internal combustion engines that generate power by injecting air and fuel into a combustion chamber and burning them. A piston that reciprocates at high speed is installed in the cylinder block of such an automobile engine, and the piston rotates the crankshaft through the connecting rod by receiving the high temperature and high pressure combustion pressure generated in the combustion chamber.

The piston is driven under severe conditions, such as exposing the piston head to high-temperature combustion gases, shockingly receiving high pressure, and generating large friction due to high-speed reciprocating motion in the cylinder block. Therefore, the piston must be manufactured to sufficiently exhibit its function even under the severe conditions of continuous high temperature and must be made of a material having good thermal conductivity and heat resistance as well as light and sturdy.

In addition, in a typical piston, an annular oil gallery is installed inside the piston body, that is, inside the groove for the top ring, to prevent damage to the piston due to high temperature combustion heat and to cool the inside of the piston. On the side, an inlet port for oil inflow and an outlet port for discharge are formed respectively.

Accordingly, when the engine is operated, a part of the oil flows into the oil gallery through the inlet and then circulates to cool the piston body and the ring carrier, and the circulated oil is discharged out of the body through the outlet. It represents a ring coupling portion in which a groove to which the top ring is coupled is formed. On the other hand, the piston should be as small as possible inertial mass according to the reciprocating motion characteristics, and for this purpose, the lower part of the piston is cut into a skirt shape to minimize the area in contact with the inner wall of the cylinder block. The part is called the piston skirt part.

The piston skirt part causes friction with the inner wall of the cylinder block by the reciprocating motion of the piston, and therefore, the piston skirt part is generally coated with a wear-resistant lubricant film to reduce friction and wear with the inner wall of the cylinder block. Looking at the friction and wear behavior of the piston skirt, when the piston moves up and down in the cylinder block, the top and bottom dead centers become boundary lubrication areas, and the other areas become fluid lubrication areas.

To reduce friction and improve abrasion resistance to reduce fuel economy in the boundary lubrication area, tin plating has been applied. Recently, carbon coating and MoS ₂ coating have been applied, and break-in (break-in) has been applied to improve the initial fuel economy of the engine. in) The demand for time reduction is also on the rise.

On the other hand, there is a limit to improving the low friction and lubrication function while maintaining high heat resistance even in a continuous high temperature environment inside the engine of the skirt part coating layer.

Registered Patent Publication No. 10-1766085 (2017.08.01.) Unexamined Patent Publication No. 2007-0081566 (2007.08.17.)

An object of the present invention is to provide a solid lubricating coating composition for engine piston silk printing with improved low friction and lubricating function.

In addition, it is an object of the present invention to provide a solid lubricating coating composition for engine piston silk printing having an average friction coefficient of 0.03 or less while maintaining high heat resistance even in a continuous high temperature environment while improving low friction and lubricating function.

The solid lubricating coating composition for an engine piston of a vehicle according to the present invention for achieving the above object is a solid lubricating coating composition for an engine piston of a vehicle, at least one selected from the group consisting of a phenol resin, an epoxy resin, and a polyamide imide resin. A binder; A solid lubricant; additive; And a solvent.

The solid lubricant may include at least one selected from the group consisting of boron nitride, graphite, molybdenum disulfide, and polytetrafluoroethylene.

The binder is a polyamide imide resin, and the polyamide imide resin may contain 45 to 85% by weight based on the total weight of the solid lubricant coating composition.

The binder is a polyamide imide resin, and the polyamide imide resin may contain 55 to 90% by weight based on the total weight of the solid lubricant coating composition.

The binder is a polyamide imide resin, the polyamide imide resin contains 45 to 85% by weight based on the total weight of the solid lubricant coating composition, and the solid lubricant includes 6 to 30% by weight of boron nitride; 2 to 10% by weight of graphite; Molybdenum disulfide may contain 1 to 9% by weight and 2 to 10% by weight of polytetrafluoroethylene.

Head part; And a skirt part connected to the head part and located below,

The skirt portion main body; And a solid lubricant coating layer formed on the body,

The solid lubrication coating layer may be formed of the solid lubrication coating composition for engine piston silk printing.

The coating layer may have an average friction coefficient of 0.03 or less.

The solid lubricating coating composition for engine piston silk printing according to the present invention can maintain high heat resistance and low friction of the piston under conditions inside the engine where the high temperature is continuously maintained, while improving durability.

1 is a photograph showing the experimental results made under a certain condition of the piston specimen formed with the solid lubricant coating composition according to the first embodiment of the present invention.
Figure 2 is experimental data measuring the coefficient of friction of Figure 1;
3 is a photograph showing the results of an experiment performed under a certain condition on a piston specimen formed with a solid lubricating coating composition according to a second embodiment of the present invention.
4 is an experimental data measuring the coefficient of friction of FIG. 3.
Figure 5 is a photograph showing the experimental results made under a certain condition of the piston specimen formed with the solid lubricant coating composition according to the third embodiment of the present invention.
6 is an experimental data measuring the coefficient of friction of FIG. 5.
7 is a photograph showing the results of an experiment performed under a certain condition on a piston specimen formed with a solid lubricating coating composition according to a third embodiment of the present invention.
8 is experimental data measuring the coefficient of friction of FIG. 7.
9 is a front photograph showing a piston in which a coating layer is formed on a skirt portion according to an embodiment of the present invention.
10 is a table showing the adhesion test results of a piston specimen formed with a solid lubricant coating composition according to an embodiment of the present invention.

Terms used in the present invention "form on the top", "form on the top (upper side)", "form on the bottom (bottom)", "install on the top", "install on the top (upper side)" and "bottom (bottom) The term "installed on" does not mean that the components are directly in contact with each other to form a stack (installation), but includes a meaning in which other components are further formed (installed) between the components.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The accompanying drawings show exemplary embodiments of the present invention, which are provided only to aid understanding of the present invention.

The solid lubricating coating composition for engine piston silk printing according to the present invention is a solid lubricating coating composition applied to an engine piston of a high-power automobile, comprising a binder consisting of at least one of a phenol resin, an epoxy resin, and a polyamide imide resin, and a solid Lubricants and additives may be included.

In detail, the solid lubricant coating composition for engine piston silk printing according to the present invention includes a binder made of polyamide imide resin, at least one solid lubricant selected from the group consisting of boron nitride, graphite, molybdenum disulfide, and polytetrafluoroethylene. , 1 to 5% by weight of an additive and 1 to 20% by weight of a dimethylacetamide solvent may be included.

The binder may be made of at least one of 5 to 25% by weight of a phenol resin, 5 to 15% by weight of an epoxy resin, and 40 to 90% by weight of a polyamide imide resin. In particular, the polyamide-imide resin may provide adhesion to the skirt portion 15 of the piston 10 while specifically collecting particulate components included in the coating solution. Preferably, the polyamide imide resin may be included in an amount of 50% to 84% by weight based on the total weight of the coating solution.

The solid lubricant may be added for the purpose of lubrication of the surface of the body 17 of the skirt part 15. In addition, spherical particles having good dispersibility and not significantly deteriorating lubricity can be used. For example, poly-tetrafluoroethylene (PTFE), graphite, molybdenum disulfide (MoS ₂ ), graphene, boron nitride (BN), WS ₂ , PbS, Sb ₂ O ₃ , PbO, Polyetherether ketone (PEEK), Carbon black, etc. can be used.

Specifically, the solid lubricant may include at least one selected from the group consisting of 8 to 35% by weight of boron nitride (BN), graphite, molybdenum disulfide, and polytetrafluoroethylene.

Among the composition components of the coating agent, BN powder has higher heat resistance and lower friction than other solid lubricants, so that low friction maintenance and durability of the piston can be improved under conditions inside the engine where high temperatures are continuously maintained. BN (Boron Nitride; Boron Nitride) powder has a plate-shaped crystal structure and has opposite characteristics. For example, it is a soft material, plays a role of polishing, has a high electrical resistance, but has good thermal conductivity, and has excellent chemical resistance, oxidation resistance, and corrosion resistance. There are several types of BN powder according to particle distribution, purity, and specific surface area. When added to a polymer and used as a filler or additive, thermal conductivity, thermal expansion, and electrical resistance may vary depending on the grade. BN powder, which is used as a refractory material and used as a brake system or traditional lubricant for aircraft requiring high performance, has various properties. The main characteristics of BN powder are inorganic compounds, white powder, plate-shaped crystal structure, and theoretical density of 2.27g/cm3. The main uses of BN powder include lubricants, fillers or additives for various polymers (silicon and epoxy, etc.) to improve thermal conductivity and electrical resistance, paints or mold release agents, refractory materials (blocking chemical reactions of molten metals), and electrical insulation. , High-tech ceramics, coatings for metal and glass industries, etc.

Graphite generally has a characteristic of a raw material whose strength increases as the temperature rises. Because it has strong thermal resistance and small thermal expansion, it has a similar function to PTFE and can be used as a filler together.

Polytetrafluoroethylene (PTFE) is a component that can be further added to form the coating layer 20 having a low coefficient of friction. Due to the strong chemical bonding of fluorine and carbon, it forms a very stable compound, so it has almost perfect inertness, heat resistance, non-adhesion, and low coefficient of friction. In addition, the coating layer 20 may function to improve lubricity, releasability, and abrasion resistance.

Specifically, the solid lubricant may include 6 to 30% by weight of boron nitride, 2 to 10% by weight of graphite, 1 to 9% by weight of molybdenum disulfide, and 2 to 10% by weight of polytetrafluoroethylene among 8 to 35% by weight. In particular, boron nitride may account for 80 to 90% of the total solid lubricant composition. If the content is less than or exceeding it, it is sintered at high temperatures, the durability is poor, and the airtightness may decrease. Therefore, in the case of having a range of 6 to 30% by weight of boron nitride, low friction maintenance and durability of the piston may be improved under conditions inside the engine in which high temperature is continuously maintained due to high heat resistance and low friction.

The additive may comprise 1 to 5% by weight based on the total weight of the coating composition. Among the additives, the curing agent is for curing, which may be selected from, for example, an isocyanate system. In one example, the curing agent may be selected from block isocyanates as latent curing agents. The dispersant is not particularly limited as long as it can improve the dispersibility of each component, and if it can prevent air bubbles. The leveling agent may be for surface smoothness of the coating layer. In the present invention, the dispersing agent, the antifoaming agent, and the leveling agent may be selected from those commonly used. At this time, based on the total weight of the coating solution, the curing agent may be included in 3% to 10% by weight, the dispersant at 0.5% to 2% by weight, the antifoaming agent at 0.2% to 0.5% by weight, and the leveling agent at 1% to 3% by weight. have. In the contents of the curing agent, dispersant, antifoaming agent, and leveling agent, if the content of each component is outside the above range, the function obtained from each component may be insignificant, or the synergistic effect due to excessive use may not be very large and economical. It may also be undesirable from the side. Meanwhile, the additives are not limited thereto, and additives such as flow-control additives, antifoaming agents, wetting agents, dispersing aids or rheological additives, and Auxiliary substances may also be contained.

The coating of the piston is usually carried out by a screen printing process. For this application, a particularly preferred solvent is a high boiling point solvent.

Suitable solvents are, for example, butyl glycol acetate, ethyl glycol acetate, dipropylene glycol, dipropylene glycol butyl ether, butoxyethanol ) And dimethylacetamide (hereinafter referred to as DMA _C ).

In particular, methylacetamide (hereinafter referred to as DMA _C ) is an bipolar aprotic solvent used in many organic reactions and industrial fields, and is a multi-purpose solvent with high boiling point and excellent thermal and chemical stability. That is, DMA _C may be an excellent solvent for polyamide imide resin (PAI) having high heat resistance in both coating and film production. These solvents may be included in the range of 5 to 15% by weight based on the total weight of the coating liquid. In addition, it is not limited only to the type of the solvent described above, and may be selected from water, an organic solvent, and a mixture thereof, and as the organic solvent, alcohols and ketones may be effectively used.

Hereinafter, each of Examples and Comparative Examples of the present invention is illustrated. The following examples are provided merely to help the understanding of the present invention, but the technical scope of the present invention is not limited thereto. In addition, the comparative example does not imply a prior art, which is provided only for comparison with the examples.

[Comparative Example 1]

A coating solution was prepared with the components and contents shown in the following [Table 1]. At this time, at least one solid lubricant selected from the group consisting of 15 to 25% by weight of phenolic resin, 10 to 15% by weight of epoxy resin, 9 to 14% by weight of graphite, MoS ₂ , WS ₂ , BN and PTFE , 6-8% by weight of the additive and the remaining amount of the solvent were mixed.

Preferably, at least one solid lubricant selected from the group consisting of 25% by weight of phenolic resin, 15% by weight of epoxy resin, 9% by weight of graphite, MoS ₂ , WS ₂ , BN and PTFE, 6% by weight A specimen was prepared by taking an appropriate amount of each component including the additive and 45% by weight of the solvent and mixing, and then sufficiently pulverizing and dispersing.

Each of FIGS. 1, 3, 5, and 7 is illustrated by taking pictures of sample samples of the coating compositions prepared according to Examples 3 to 6.

In the following [Table 1], the content (% by weight) of each component is based on the total weight of the coating composition.

[Comparative Example 2]

At least one solid lubricant selected from the group consisting of 10 to 30% by weight of phenolic resin, 10 to 30% by weight of epoxy resin, 10 to 30% by weight of graphite, MoS ₂ , WS ₂ and BN, 5 to 30 The mixture was mixed including the weight% of the additive and the remaining amount of the solvent.

Preferably, at least one solid lubricant selected from the group consisting of 30% by weight of phenolic resin, 30% by weight of epoxy resin, 10% by weight of graphite, MoS ₂ , WS ₂ and BN, 5% by weight of additives And 25% by weight of each component including a solvent were taken and mixed, and a specimen was prepared in the same manner as in Example 1.

[Example 1]

FIG. 1 is a photograph showing an experiment result of a piston specimen formed with a solid lubricating coating composition according to a first embodiment of the present invention under certain conditions, and FIG. 2 is an experimental data obtained by measuring the coefficient of friction of FIG. 1.

The solid lubricating coating composition for engine piston silk printing according to the first embodiment of the present invention is a group consisting of 45 to 85% by weight of polyamidiimide resin (PAI), 8 to 35% by weight of graphite, MoS ₂ , PTFE and BN At least one solid lubricant selected from, 1 to 5% by weight of an additive, and 1 to 20% by weight of a DMA _C solvent were mixed.

Preferably, the solid lubricant coating composition for engine piston silk printing according to the first embodiment of the present invention is 55% by weight of polyamidiimide resin (PAI), 30% by weight of graphite, MoS ₂ , WS ₂ , BN and PTFE After taking an appropriate amount of each component including at least one solid lubricant selected from the group consisting of, 5% by weight of an additive, and 10% by weight of a solvent, and mixing, a specimen was prepared in the same manner as in Example 1.

The results of high heat resistance according to the specific components and contents of the coating solutions according to each of Examples 1 to 3 are as shown in Table 1 below.

<High heat resistance results according to the components and content of the coating composition> division Content (% by weight) Comparative Example 1 Comparative Example 2 Example 1 Phenolic resin 25 30 - Epoxy resin 15 30 - PAI ^* - - 55 PTFE ^* 9 - 30 Graphite ^* 10 MoS ₂ ^* BN ^* WS ₂ ^* - Additive ^* 6 5 5 Solvent ^* 45 25 10 In a high-temperature environment (over 1000℃) inside the engine (visual) Some peeling Some peeling Keep intact * PAI: Polyamide imide resin
* PTFE: Poly-tetrafluoroethylene
* Graphite: Graphite (graphite)
* MoS ₂ : Molybdenum disulfide
* BN: Boron Nitride
* WS ₂ : Tungsten disulfide
* Solvent: DMA _C (methylacetamide; Dimethylacetamide)
* Additives: Includes hardeners, dispersants, antifoaming agents and leveling agents.
* Solvent:
-Examples 1 and 2 are butyl glycol acetate, ethyl glycol acetate, dipropylene glycol, dipropylene glycol butyl ether, and butoxyethanol (Butoxyethanol) at least any one
-Example 3 is dimethylacetamide (Di Methyl Acetamide, DMA _C )

As shown in [Table 1], in the case of Example 3 of Examples 1 to 3, it was visually confirmed that seizure did not occur even in a high temperature environment inside the engine of 1000°C or higher and had a lubricating function. Therefore, it was found that Example 1, unlike Comparative Example 1 and Comparative Example 2, contained a polyamide imide resin (PAI) as a binder, so that high heat resistance was excellent.

<Wear resistance test>

The coating solution according to each of the Examples and Comparative Examples was screen-coated once on an aluminum (Al) plate, and then cured at 220° C. for about 30 minutes. Thereafter, after leaving it for about 2 hours, using a reciprocating wear tester (UK, Plint, manufactured model name-TE77), the coefficient of friction was calculated for each coated specimen according to the test conditions in [Table 2] below. Measured. The results are shown in the following [Table 3].

<Abrasion resistance test conditions> Average load Average speed Number of exams Distance (length) 10Kg _f 3Hz 30,484 times 329,231mm

<Adhesion test>

The coating solution according to each example was screen-coated once on aluminum foil and then cured at 220° C. for about 30 minutes. Thereafter, after being left for about 2 hours, adhesion was evaluated using a 90 degree (angle) peel test method in a peel strength tester. At this time, when peeling at a speed of 5 m/min, "△" when peeling occurs under a load of 10Kg, "○" when peeling occurs under a load between 10Kg and 20Kg, and peeling does not occur under a load of 20Kg. If not, it was evaluated as "◎" and the results are shown in Table 3 below.

[Example 2]

3 is a photograph showing an experiment result of a piston specimen formed with a solid lubricating coating composition according to a second embodiment of the present invention under certain conditions, and FIG. 4 is an experimental data obtained by measuring the coefficient of friction of FIG. 3.

The solid lubricating coating composition for engine piston silk printing according to the second embodiment of the present invention is a group consisting of 45 to 85% by weight of polyamidiimide resin (PAI), 8 to 35% by weight of graphite, MoS ₂ , PTFE and BN At least one solid lubricant selected from, 1 to 5% by weight of an additive, and 1 to 20% by weight of a DMA _C solvent were mixed.

Preferably, the solid lubricant coating composition for engine piston silk printing according to the second embodiment of the present invention is 65% by weight of polyamidiimide resin (PAI), 25% by weight of graphite, MoS ₂ , WS ₂ , BN and PTFE After taking an appropriate amount of each component including at least one solid lubricant selected from the group consisting of, 5% by weight of an additive, and 5% by weight of a solvent, and mixing them, a specimen was prepared in the same manner as in Example 1.

[Example 3]

5 is a photograph showing an experiment result of a piston specimen formed with a solid lubricating coating composition according to a third embodiment of the present invention under certain conditions, and FIG. 6 is an experimental data obtained by measuring the coefficient of friction of FIG. 5.

The solid lubricant coating composition for engine piston silk printing according to the third embodiment of the present invention is a group consisting of 55 to 90% by weight of polyamidiimide resin (PAI), 10 to 40% by weight of graphite, MoS ₂ , PTFE and BN At least one solid lubricant selected from, 1 to 5% by weight of an additive, and 1 to 20% by weight of a DMA _C solvent were mixed.

Preferably, the solid lubricating coating composition for engine piston silk printing according to the third embodiment of the present invention is a group consisting of 85% by weight of polyamidiimide resin (PAI), 10% by weight of graphite, MoS ₂ , BN and PTFE. After taking and mixing an appropriate amount of each component including at least one solid lubricant selected from, 2% by weight of an additive and 3% by weight of a solvent, a specimen was prepared in the same manner as in Example 1.

[Example 4]

7 is a photograph showing an experiment result of a piston specimen formed with a solid lubricating coating composition for engine piston silk printing according to a fourth embodiment of the present invention under certain conditions, and FIG. 8 is an experimental data obtained by measuring the coefficient of friction of FIG. 7. .

The solid lubrication coating composition for engine piston silk printing according to the fourth embodiment of the present invention is a group consisting of 55 to 90% by weight of polyamidiimide resin (PAI), 10 to 40% by weight of graphite, MoS ₂ , PTFE and BN At least one solid lubricant selected from, 1 to 5% by weight of an additive, and 1 to 20% by weight of a DMA _C solvent were mixed.

Preferably, the solid lubricating coating composition for engine piston silk printing according to the fourth embodiment of the present invention is a group consisting of 40% by weight of polyamidiimide resin (PAI), 40% by weight of graphite, MoS ₂ , BN and PTFE. After taking and mixing an appropriate amount of each component including at least one solid lubricant selected from, 5% by weight of an additive and 15% by weight of a solvent, a specimen was prepared in the same manner as in Example 1.

In Examples 1 to 4, the results of abrasion resistance tests according to specimens having different contents of the coating composition are shown in Table 3 below.

<Results of evaluation of high temperature heat resistance, adhesion and abrasion resistance according to the content of the coating composition> Item Content (% by weight) Example 1 Example 2 Example 3 Example 4 PAI 55 65 45 85 PTFE, Graphite, MoS ₂ , BN 30 25 35 10 additive 5 5 5 2 Solvent (DMA _C ) 10 5 15 3 High temperature heat resistance as it is
maintain as it is
maintain a little
exfoliation Keep intact Adherence
(90 degree peeling) ◎ ◎ ○ ◎ Wear resistance Average coefficient of friction 0.024 0.019 0.067 0.046 Coefficient of friction 0.034 0.024 0.069 0.057 * "△": When peeling occurs under a load of 10Kg,
"○": When peeling occurs under a load between 10Kg and 20Kg
"◎": When no peeling occurs under a load of 20Kg

As shown in [Table 3] and Figs. 1 to 4, each of Examples 1 and 2 has an average coefficient of friction of 0.03 or less when compared to Examples 3 and 4, indicating high wear resistance and lubricity. Therefore, when comparing Examples 1 to 4 and Comparative Examples 1 and 2, it can be seen that at least high heat resistance and abrasion resistance are significantly different depending on whether or not polyamide imide (PAI) is used.

On the other hand, looking at the specimen surfaces of Figs. 1 and 3 and Figs. 5 and 7 shown by taking a picture, it can be seen that in the case of Examples 3 and 4, scratches due to abrasion of the surface are clearly revealed. .

[Table 3] Looking at the results, Example 1 exhibited a low coefficient of friction of 0.024 on average, and Example 2 exhibited a coefficient of friction of 0.019 on average, which is lower than that of Example 1. That is, since each of Examples 1 and 2 exhibited a low coefficient of friction of 0.03 or less, it has excellent wear resistance, as well as lubricity, adhesion, corrosion resistance, and thermal stability, and is particularly suitable for contact surfaces, so it is suitable for high mechanical friction of precision lubrication. It can be closely attached. In addition, after coating with a solid lubricant coating composition for silk printing on the skirt portion 15 of the piston 10, the state is highly useful for a long time and the life of the piston 10 can be improved. On the other hand, when the content is out of the above range, the average coefficient of friction is increased to 0.03 or more as in Examples 5 and 6, and thus wear resistance may be relatively low compared to Examples 3 and 4.

Accordingly, since each of Examples 1 to 4 contains 55 to 90% by weight of the polyamide imide resin, when it exceeds 55% by weight, high temperature heat resistance may be insufficient. In addition, when it exceeds 90% by weight, the content of the solid lubricant is relatively low, so that adhesion and abrasion resistance may increase.

In addition, as compared to Examples 3 and 4, each of Examples 1 and 2 contains 45 to 85% by weight of a polyamide imide resin, and when less than 45% by weight, adhesion and abrasion resistance are relatively low, but between product surfaces. Adhesion, particle agglomeration and strength reinforcement may be insignificant, and high temperature heat resistance may be insufficient. In addition, when it exceeds 85% by weight, the content of other additives and solvents is relatively low, so that the high temperature heat resistance is relatively good, but abrasion resistance and frictional force may be increased.

Therefore, according to the present invention, each of the first and second embodiments has high heat resistance and at the same time has low friction, so that the low friction maintenance and durability of the piston can be improved under conditions inside the engine where the high temperature is continuously maintained.

9 is a front photograph showing a piston having a coating layer formed on a skirt portion according to an embodiment of the present invention.

Referring to FIG. 9, the piston 10 according to the embodiment of the present invention may include a head portion 13 and a skirt portion 15 located below the head portion 13 and connected to the head portion 13. The skirt portion 15 may be formed with a coating layer 20 made of a solid lubricant coating composition for silk printing of the engine piston 10 on the main body 17 and the main body 17.

Here, as the surface tension of the coating layer 20 increases, the coating adhesion with the skirt portion 15 may be improved. In the case of the coating layer 20 in which peeling and air bubbles are generated when viewed with the naked eye, it may lead to scuffing of the piston 10, resulting in a risk that the engine may stop as well as deterioration of engine performance. The piston 10, which is uniformly and evenly coated, has a uniform quality of the coating layer 20, does not have flaws, bubble peeling, etc. that are harmful to use, and can have sufficient durability even during actual engine operation.

The coating layer 20 may be formed on the skirt portion 15 with a solid lubricant coating composition as in Examples 1 to 6. This coating layer 20 may be formed with a constant coating thickness. This coating layer 20 can increase lubricity on the surface of the main body 17 on the skirt portion 15 of the piston 10, improve low friction and wear resistance even when the engine output increases, and improve fuel economy. That is, the coating layer 20 may have a friction coefficient of 0.03 or less and abrasion resistance may be formed.

10 is a table showing the adhesion test results of a piston specimen formed with a solid lubricant coating composition according to an embodiment of the present invention.

Referring to Figure 10, as showing the adhesion test results of [Table 3], except for Example 3 showing the result of "○" in which peeling occurred under a load between 10Kg and 20Kg, Examples 1, 2 and Since each of Example 4 was evaluated as "◎" in which no peeling occurred under a load of 20 Kg, it was found that adhesion was excellent.

The rights of the present invention are not limited to the embodiments described above and are defined by what is described in the claims, and a person of ordinary skill in the technical field of the present invention can make various modifications and adaptations within the scope of the rights described in the claims. It is self-evident.

10: piston 13: head portion
15: skirt part 17: main body
20: coating layer

Claims (7)

As a solid lubricant coating composition for engine pistons of automobiles,
At least one binder selected from the group consisting of a phenol resin, an epoxy resin, and a polyamide imide resin;
A solid lubricant;
additive; And
A solid lubricant coating composition for an engine piston of an automobile comprising a solvent. The method of claim 1,
The solid lubricant,
Boron nitride, graphite, molybdenum disulfide, and a solid lubricating coating composition for an engine piston of a vehicle comprising at least one selected from the group consisting of polytetrafluoroethylene. The method of claim 1,
The binder is a polyamide imide resin,
The polyamide imide resin is a solid lubricant coating composition for an engine piston of a vehicle, comprising 45 to 85% by weight based on the total weight of the solid lubricant coating composition. The method of claim 1,
The binder is a polyamide imide resin,
The polyamide imide resin is a solid lubricant coating composition for an engine piston of an automobile, comprising 55 to 90% by weight based on the total weight of the solid lubricant coating composition. The method of claim 3,
The binder is a polyamide imide resin,
The polyamide imide resin contains 45 to 85% by weight based on the total weight of the solid lubricant coating composition,
The solid lubricant,
6 to 30% by weight of boron nitride;
2 to 10% by weight of graphite;
1 to 9% by weight of molybdenum disulfide and
A solid lubricant coating composition for an engine piston of an automobile, comprising 2 to 10% by weight of polytetrafluoroethylene. Head part; And
And a skirt part connected to the head part and located below,
The skirt part,
main body; And
Including a solid lubricant coating layer formed on the body,
The solid lubrication coating layer is an engine piston of a vehicle, characterized in that formed of the solid lubrication coating composition for engine piston silk printing of any one of claims 1 to 4. The method of claim 6,
The coating layer,
Automotive piston, characterized in that it has an average coefficient of friction of 0.03 or less.

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