JP6036005B2 - Thermal insulation structure for engine combustion chamber member and method for manufacturing the same - Google Patents

Description

  The present invention relates to a heat insulating structure in which a heat insulating layer is formed on the surface of a base material of a component constituting an engine combustion chamber, and a method for manufacturing the same.

In the 1980s, as a method for increasing the thermal efficiency of the engine, it was proposed to provide a heat insulating layer in a portion facing the engine combustion chamber (see, for example, Patent Document 1), and thereafter, a heat insulating layer made of a ceramic sintered body, or zirconia insulation layer made of thermally sprayed layer containing a (ZrO ₂₎ particles has been proposed to have a low thermal conductivity.

  However, the use of a ceramic sintered body causes problems such as generation of cracks due to thermal stress and thermal shock, and generation of cracks. For this reason, in particular, those in which a heat insulating layer made of a ceramic sintered body is applied to a portion having a relatively large area such as the top surface of the piston, the inner peripheral surface of the cylinder liner, and the lower surface of the cylinder head has reached practical use. Not in.

On the other hand, the sprayed layer itself has been used for the trochoidal surfaces of cylinder liners and rotary engines, but it is intended to improve wear resistance and not to improve heat resistance. In order to use the thermal spray layer as a heat insulating layer, it is preferable to spray a low thermal conductive material mainly composed of ZrO ₂ as described above. However, the zirconia-based layer has better adhesion between particles than the cermet-based layer. Since it is inferior, there exists a problem that it is easy to produce a crack by the fatigue etc. by a thermal stress or repeated stress.

In order to solve such a problem, for example, Patent Document 2 proposes a heat insulating thin film including a particulate first heat insulating material, a film-shaped second heat insulating material, and a reinforcing fiber material. Yes. In Patent Document 2, it is described that the second heat insulating material has a function of bonding the first heat insulating material. As the particulate first heat insulating material, hollow ceramic beads, hollow glass beads, silica Examples thereof include a heat insulating material having a fine porous structure mainly composed of (silicon dioxide, SiO ₂ ), silica airgel, and the like. The film-like second heat insulating material includes ceramics such as zirconia (ZrO ₂ ), silicon, titanium, and zirconium, ceramics mainly composed of carbon and oxygen, and high-strength and high-heat-resistant ceramic fibers. Illustrated. Further, it is described that the second heat insulating material is coated or bonded to the base material.

In addition, Patent Document 3 describes a SiO ₂ ceramic layer including a hollow portion. Specifically, the hollow portion is formed by hollow inorganic compound particles formed by forming a layer containing a spherical resin whose surface is coated with an inorganic compound and then heating the layer to burn off the spherical resin. It is configured. In Patent Document 3, by heating the SiO ₂ ceramic layer, the resin in each particle is thermally decomposed and gasified, and the gas generated by the thermal decomposition of the organosilicon compound is extracted from the film. This prevents a decrease in film strength due to residual gas.

International Publication No. 89/03930 Pamphlet JP 2009-243352 A JP 2010-077092 A

  Patent Document 2 only describes that the second heat insulating material is coated or bonded to the base material, but does not describe in detail how to obtain the heat insulating thin film. In view of the fact that a ceramic material is used as the second heat insulating material, it is estimated that the heat insulating thin film is similar to a ceramic sintered body. Moreover, patent document 2 is not disclosing about effectively suppressing the deformation | transformation by cracking pressure etc. and generation | occurrence | production of a crack.

On the other hand, when the base material of the engine combustion chamber is made of an aluminum alloy, the SiO ₂ ceramic layer thin film of Patent Document 3 has a large difference in thermal expansion coefficient, so that the thin film may be cracked or peeled off. Further, since the degassed portion is in communication with the surface, there is a problem such as fuel penetration.

Therefore, it is conceivable that the entire heat insulating layer is not made of a SiO ₂ ceramic layer, but is mainly made of a silicone resin containing hollow particles as a material having a small difference in thermal expansion coefficient from the aluminum alloy. However, since the silicone resin generally has a low hardness, if the wall surface of the engine combustion chamber is covered with the silicone resin, the heat insulating layer may be deformed by the pressure from the compression stroke to the time of combustion. When the heat insulating layer is deformed, the compression ratio is changed, so that the engine performance is greatly affected. Furthermore, since the thin film of Patent Document 3 has a structure in which hollow inorganic compound particles are only physically covered with SiO 2 or the like, their bonding strength is weak, and a gap may be formed at the interface. Such a gap can be a cause of cracks by being exposed to a pressure fluctuation cycle for a long period of time.

  The present invention has been made in view of the above problems, and its purpose is to prevent the occurrence of cracks and peeling by using a material with a small difference in thermal expansion coefficient from the base material of the engine component for the heat insulating layer. By increasing the strength of the heat insulating layer, deformation due to combustion pressure or the like is prevented, and further, penetration of fuel is prevented.

  In order to achieve the above object, the present invention uses a silicone-based resin and hollow particles as a material of a heat insulating layer used for a heat insulating structure of an engine combustion chamber member, and these can be bonded to each other.

Specifically, in the heat insulating structure of the engine combustion chamber member according to the present invention, a heat insulating layer is formed on the surface of the base material of the parts constituting the engine combustion chamber, and the heat insulating layer includes a silicone resin, hollow particles, and the like. The surface of the hollow particles is treated with an organic compound that can be covalently bonded to the silicone resin, and the silicone resin and the hollow particles are bonded with the organic compound capable of covalent bonding, The heat insulating layer contains a chain siloxane having a fluoroalkyl group .

According to the heat insulation structure for an engine combustion chamber member according to the present invention, since the heat insulation layer is formed of a silicone-based resin, for example, when the heat insulation layer is provided on an engine combustion chamber member made of an aluminum alloy, each thermal expansion is performed. The difference in rate can be reduced. For this reason, it can prevent that a peeling, a crack, etc. arise in a heat insulation layer resulting from the difference of those thermal expansion coefficients. Moreover, since the said heat insulation layer contains a hollow particle, the heat conductivity can be reduced more. Furthermore, since the surface of the hollow particle is treated with an organic compound that can be covalently bonded to the silicone resin, the silicone resin and the hollow particle are bonded to each other by covalent bonding of the silicone resin and the organic compound. Indirectly coupled. As a result, since the bond between the hollow particles and the silicone resin is strengthened, a heat-insulating layer having high strength can be obtained, so that the heat-insulating layer is prevented from being deformed due to combustion pressure or the like, and further to the heat-insulating layer. Prevent the infiltration of fuel. Moreover, since the heat insulation layer contains a chain siloxane having a fluoroalkyl group having oil repellency and oil resistance, the fuel resistance of the heat insulation layer can be improved.

  In the heat insulating structure of the engine combustion chamber member according to the present invention, a silane compound can be used as the organic compound.

  At this time, the reaction between the alkoxyl group of the silicone resin and the alkyl group of the silane compound, the reaction between the alkyl group of the main chain of the silicone resin and the alkoxyl group of the silane compound, and the alkoxyl group and silane of the main chain of the silicone resin The silicone resin and the hollow particles may be indirectly bonded by a covalent bond formed by at least one of the reactions with the alkoxyl group of the compound.

  If it does in this way, as above-mentioned, since the coupling | bonding of a hollow particle and silicone resin becomes strong, a heat insulation layer with higher intensity | strength can be obtained.

  In the heat insulating structure for an engine combustion chamber member according to the present invention, it is preferable that at least one of a chemical conversion treatment layer and an alumite treatment layer is provided between the surface of the base material of the component and the heat insulation layer.

  If it does in this way, the adhesiveness of the base-material surface of an engine combustion chamber component and a heat insulation layer can be improved.

In the heat insulating structure of the engine combustion chamber member according to the present invention, a SiO ₂ layer may be formed on the surface of the heat insulating layer.

  In addition to this, a plating layer may be formed on the surface of the heat insulating layer.

According to them, since the surface in contact with the fuel in the heat insulation layer is protected by the SiO ₂ layer or the plating layer, the fuel resistance of the heat insulation layer can be improved.

The method for manufacturing a heat insulating structure for an engine combustion chamber member according to the present invention is directed to a method for manufacturing a heat insulating structure in which a heat insulating layer is formed on the surface of a base material of a component constituting the engine combustion chamber. A step of treating the substrate with an organic compound that can be covalently bonded to the silicone resin, a step of obtaining a heat insulating material obtained by mixing the silicone resin and the hollow particles, and a base material for a component constituting the engine combustion chamber. Forming a heat insulating layer in which a silicone resin and an organic compound are covalently bonded to each other, and the heat insulating layer includes a chain siloxane having a fluoroalkyl group .

According to the method for manufacturing a heat insulation structure for an engine combustion chamber member according to the present invention, in order to produce a heat insulation layer using a silicone-based resin, for example, when the heat insulation layer is provided on an engine combustion chamber member made of an aluminum alloy, The difference in coefficient of thermal expansion can be reduced. For this reason, it can prevent that a peeling, a crack, etc. arise in a heat insulation layer resulting from the difference of those thermal expansion coefficients. Moreover, since the said heat insulation layer contains a hollow particle, the heat conductivity can be reduced more. Furthermore, since the surface of the hollow particles is treated with an organic compound that can be covalently bonded to the silicone resin, the silicone resin and the hollow organic particles are bonded to each other by covalent bonding of the silicone resin and the organic compound. Indirectly coupled. As a result, since the bond between the hollow particles and the silicone resin becomes strong, a heat insulating layer with higher strength can be obtained. Moreover, since the heat insulation layer contains a chain siloxane having a fluoroalkyl group having oil repellency and oil resistance, the fuel resistance of the heat insulation layer can be improved.

  In the method for manufacturing a heat insulating structure for an engine combustion chamber member according to the present invention, it is preferable to use a silane compound as the organic compound.

  In this case, since the silane compound can be covalently bonded to the silicone resin, the bond between the hollow particles and the silicone resin can be strengthened, and a heat insulating layer with higher strength can be obtained.

  In this case, the reaction between the alkoxyl group of the main chain of the silicone resin and the alkyl group of the silane compound, the reaction of the alkyl group of the main chain of the silicone resin with the alkoxyl group of the silane compound, and the alkoxyl of the main chain of the silicone resin A thermal bond can be obtained by forming a covalent bond by at least one of the reaction between the group and the alkoxyl group of the silane compound.

According to the heat insulating structure of the engine combustion chamber member and the manufacturing method thereof according to the present invention, the heat insulating layer is made of a material having a small difference in thermal expansion coefficient from the base material of the engine component. It is possible to prevent the occurrence of cracks and peeling. In addition, since the hollow particles in the heat insulating layer and the silicone resin can be combined, a heat insulating layer having high strength can be obtained, and deformation due to combustion pressure and the like can be prevented, and the heat insulating layer can be cracked and peeled off. Can be prevented, and further, the infiltration of fuel can be prevented. Moreover, since the heat insulation layer contains a chain siloxane having a fluoroalkyl group having oil repellency and oil resistance, the fuel resistance of the heat insulation layer can be improved.

It is sectional drawing which shows the engine structure which concerns on embodiment of this invention. It is sectional drawing which shows the heat insulation structure of the engine combustion chamber member which concerns on this invention.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. The following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the invention, its method of application, or its application.

  In the present embodiment, the heat insulating structure of the engine combustion chamber member is employed in the engine shown in FIG.

<Engine features>
In FIG. 1, reference numeral 1 is a piston, reference numeral 2 is a cylinder block, reference numeral 3 is a cylinder head, reference numeral 4 is an intake valve that opens and closes an intake port 5 of the cylinder head 3, reference numeral 6 is an exhaust valve that opens and closes an exhaust port 7, and reference numeral 8 is a fuel injection valve. The combustion chamber of the engine is formed by the top surface of the piston 1, the cylinder block 2, the cylinder head 3, and the valve head surfaces of the intake and exhaust valves 4 and 6 (surfaces facing the combustion chamber). A cavity 9 is formed on the top surface of the piston 1. Note that the illustration of the spark plug is omitted.

  By the way, it is known that the thermal efficiency of the engine increases theoretically as the geometric compression ratio is increased and the excess air ratio of the working gas is increased. However, in practice, as the compression ratio is increased and the excess air ratio is increased, the cooling loss increases. Therefore, the improvement of the thermal efficiency due to the increase in the compression ratio and the excess air ratio reaches its peak.

  That is, the cooling loss depends on the heat transfer rate from the working gas to the engine combustion chamber wall, the heat transfer area, and the temperature difference between the gas temperature and the wall temperature. For this reason, in the engine combustion chamber, a heat insulating structure using a heat insulating layer made of a material having a lower thermal conductivity than the metal base material of the engine component is configured.

<Insulation structure>
So, below, the heat insulation structure which concerns on this embodiment is demonstrated.

  The heat insulation structure of the engine combustion chamber member according to the present embodiment is configured by forming a heat insulation layer on the top surface of a piston, which is a component constituting the engine combustion chamber. Such a heat insulating structure of the engine combustion chamber member will be described with reference to FIG.

  As shown in FIG. 2, a heat insulating layer 11 containing a silicone resin is formed on the top surface side of the piston ring groove 10 on the top surface of the piston 1 constituting the engine combustion chamber and the outer peripheral surface of the piston 1. The heat insulating layer 11 includes hollow particles 12 in order to reduce the thermal conductivity. By providing such a heat insulating layer 11, the cooling loss in the engine combustion chamber can be reduced, and the engine performance can be improved.

  In addition, in the site | part in which the heat insulation layer 11 was formed, the chemical conversion treatment layer 13 may be formed between the heat insulation layer 11 and the base-material surface of piston 1. FIG. The chemical conversion treatment layer 13 can be formed by, for example, performing a zircon oxidation treatment on the surface of the base material of the piston 1. Further, when aluminum is used as the material of the piston 1, the anodized layer may be formed by anodizing the substrate surface of the piston 1 instead of the chemical conversion layer 13. By forming these layers, the adhesion of the heat insulating layer 11 to the substrate surface of the piston 1 can be improved. Note that both the chemical conversion treatment layer and the alumite treatment layer may be formed.

  In FIG. 2, the engine combustion chamber member has been described as the piston 1. However, the invention is naturally not limited to this, and the heat insulating layer 11 may be provided on a member constituting another engine combustion chamber such as a cylinder head.

  Next, the material etc. of the heat insulation layer used for the heat insulation structure which concerns on this embodiment are demonstrated.

The heat insulating layer according to this embodiment includes a silicone resin and hollow particles, and the surface of the hollow particles is treated with an organic compound that can be covalently bonded to the silicone resin. Is characterized by being indirectly linked.
In the present embodiment, the silicone resin refers to a resin containing a polymer compound mainly composed of polysiloxane, polycarbosilane, and the like shown in the following [Chemical Formula 1] and [Chemical Formula 2].

In the chemical formulas shown in [Chemical Formula 1] and [Chemical Formula 2], R ¹ and R ² are, for example, a hydrogen atom, alkyl group, hydroxyl group, alkoxyl group, acryloyl group, glycidyl group, vinyl group, halogen atom, aryl group, organic One or more can be selected from the group of titanium compounds or organic zircon compounds.

Further, a heat insulating layer according to the present embodiment, including the chain siloxane containing fluoroalkyl groups. That is, a fluoroalkyl group can be selected as R ¹ or R ² described above. When the heat insulating layer contains a fluoroalkyl group having oil repellency and oil resistance, the fuel resistance of the heat insulating layer can be improved.

  The hollow particles used in the heat insulating layer of the present embodiment are included in order to further reduce the thermal conductivity, and it is preferable to use inorganic oxide hollow particles. As the inorganic oxide hollow particles, for example, zirconia-containing oxide, silica-containing oxide, alumina and the like can be used as the material. Specifically, ceramic hollow particles such as alumina bubbles, fly ash balloons, shirasu balloons, silica balloons, airgel balloons, and other inorganic hollow particles can be used as the hollow particles. In addition, each material and particle size are as shown in [Table 1].

For example, the chemical composition of the fly ash _{balloons, SiO 2; 40.1~74.4%, Al} 2 O 3; 15.7~35.2%, Fe 2 O 3; 1.4~17.5%, MgO; 0.2 to 7.4%, CaO; 0.3 to 10.1% (the above is mass%). The chemical composition of the Shirasu _{balloon, SiO 2; 75~77%, Al} 2 O 3; 12~14%, Fe 2 O 3; 1~2%, Na 2 O; 3~4%, K 2 O; 2~ 4%, IgLoss; 2 to 5% (the above is mass%).

  In the present embodiment, the surface of the hollow particles as described above is treated with an organic compound that can be covalently bonded to the silicone resin. Such an organic compound has a metal atom such as Si or Al existing on the surface of the hollow particle or a functional group that can be bonded to an —OH group, and has, for example, a hydroxyl group, an alkoxyl group, or a halogen atom. . Furthermore, the organic compound preferably has an alkyl group or an alkoxyl group because it can be covalently bonded to the silicone resin, but is not limited thereto.

In the present embodiment, the organic compound as described above is particularly preferably a silane compound. The silane compound of this embodiment is a silicon compound that can be bonded to the surface of the hollow particle and covalently bonded to the silicone resin, and is a compound represented by X _a SiA _b R ³ _(4-ab) .

Here, R ³ is, for example, a hydroxyl group, an alkoxyl group, or a halogen atom. The bond between the silane compound and the surface of the hollow particle is caused by a reaction between R ^{3 of the} silane compound and a metal atom such as Si or Al present on the surface of the hollow particle or an —OH group. For this reason, R ^{3 of the} hollow particles is not limited to the above as long as it is a functional group capable of reacting with them. A is, for example, a hydrogen atom, an alkyl group, a hydroxyl group, an alkoxyl group, or a halogen atom, and X is, for example, an acryloyl group, an alkenyl group, a carboxyl group, a sulfo group, an amino group, or an aryl group. In addition, a and b satisfy | fill that a + b is an integer of 1-3, a satisfy | fills that it is 0-2 and b is an integer of 1-3.

Such a silane compound is formed by, for example, condensing the alkyl group with the alkoxyl group (R ¹ or R ² ) of the main chain of the silicone resin to form a covalent bond, thereby forming the hollow particles and the silicone resin. Can be joined indirectly. Of course, the present invention is not limited to this. For example, the alkoxyl group of the silane compound and the alkyl group of the main chain of the silicone resin (the above R ¹ or R ² ) may be covalently bonded by a condensation reaction. Alkoxyl groups may be covalently bonded by hydrolysis and condensation reactions. That is, it is sufficient that the silane compound and the silicone resin are covalently bonded and the hollow particles and the silicone resin are indirectly bonded.

  In this way, a heat insulating layer with higher strength can be obtained, and as a result, deformation due to combustion pressure and the like can be prevented, cracks and delamination can be prevented from occurring in the heat insulating layer, and fuel can be prevented. It is possible to prevent soaking in.

Thermal insulation layer of the present embodiment may be a SiO ₂ layer is formed on the surface. The SiO ₂ layer may be formed by newly applying or spraying a material containing SiO ₂ on the surface of the heat insulating layer, and the surface of the heat insulating layer is heated to actively oxidize Si contained in the heat insulating layer. May be formed. Thus, by forming the SiO ₂ layer on the surface of the heat insulating layer, the hardness, heat resistance and fuel resistance of the surface of the heat insulating layer exposed to extremely severe heat and pressure environments can be improved.

In addition to this, a plating layer may be formed on the surface of the heat insulating layer. This plating layer is also formed for the same purpose as the above-mentioned SiO ₂ layer, and for example, a plating layer made of Ni can be formed. At this time, since it is usually not possible to form a plating layer directly on the silicone resin, the surface of the silicone resin is heated so that the core material (catalyst metal) of the plating layer can be supported. it is necessary to generate the SiO _2. As the catalyst metal, for example, a Pd—Sn complex can be used.

  Below, the Example for demonstrating in detail about the heat insulation structure of the engine combustion chamber member which concerns on this invention is shown. In this example, the heat insulating layer was generated using a silicone resin and a super balloon 732C (manufactured by Showa Chemical Industry Co., Ltd.), which is a hollow particle, treated with a silane compound. On the other hand, as a comparative example, a heat insulation layer was formed using a super balloon 732C not treated with a silane compound.

  Below, the manufacturing method of the heat insulation layer of an Example and a comparative example is demonstrated, and those compositions are shown in [Table 2]. Silicone resin and hollow particles indicate the weight ratio in the solid content of the paint (excluding the solvent).

( Reference Example 1)
First, in a reaction vessel equipped with a stirrer, a thermometer and a cooling tube, 70 parts by weight of isopropanol, 30 parts by weight of hollow particles (manufactured by Showa Chemical Industry Co., Ltd., Super Balloon 732C), and 7 parts by weight of 3 as a silane compound. -Methacryloxypropyltrimethoxysilane (Toray Dow Corning Silicone Co., Ltd., SZ-6030) was added and gradually heated with stirring. After the temperature of the reaction solution reached 68 ° C., the reaction solution was further heated for 5 hours. Then, the surface of the hollow particles was treated with a silane compound by concentration under reduced pressure while continuing stirring.

  Next, in a reaction vessel equipped with a stirrer, a thermometer and a cooling tube, a mixture of polytitanocarbosilane (47.4 wt%) and methylsiloxane polysiloxane (52.6 wt%), which is a polysiloxane compound, was added. 70.0 g of a xylene / 1-butanol solution having a concentration of 45.7% by weight (Tyrannovaris: Ube Industries, VN-100) was added, and 7.5 g of 1-butanol was obtained as described above. 32.0 g of solid content of hollow particles (Super Balloon 732C: manufactured by Showa Chemical Industry Co., Ltd.) was added, and the mixture was uniformly dispersed by stirring at room temperature for 24 hours. This obtained the coating material which is a heat insulating material which concerns on Example 1. FIG.

  Next, after degreasing an aluminum plate having a plane size of 40 mm × 40 mm and a thickness of 3 mm with thinner, the entire surface to be coated in one direction is polished five times using a number 320 sandpaper. The surface was cleaned by After that, the above-mentioned paint was applied to the entire surface of the cleaned side of the aluminum plate using a spray (W-101, manufactured by Anest Iwata Co., Ltd.). The painted aluminum plate was allowed to stand at room temperature for 3 minutes, and then painted again using the paint. This coating was repeated two more times. The finished aluminum plate was left for 30 minutes.

  Then, the coating surface of the aluminum plate was dried at 80 degreeC for 10 minutes using the hot air dryer (made by Yamato Scientific company, DK-400). Subsequently, using the same hot air dryer, the coated surface of the aluminum plate was treated at 180 ° C. for 30 minutes to fix and cure the coating. As described above, the heat insulating layer according to Example 1 was formed on the surface of the aluminum plate. The film thickness of the heat insulating layer was 0.15 mm.

( Reference Example 2)
The reference example 2 is different from the reference example 1 in that the composition of the heat insulating layer itself is the same and only the alumite treatment is applied to the painted surface of the aluminum plate to be coated. For this reason, only the alumite process will be described here, and the description of the other steps will be omitted.

As an alumite treatment, an aluminum plate as a material to be treated is placed in an electrolytic bath of a 15% (w / v) sulfuric acid aqueous solution having a dissolved aluminum concentration of 5 g / L or less, a bath temperature of 20 ° C. to 25 ° C., and a current density of 60 A. / M ^{2 to} 130 A / m ² , the bath voltage was 16 V, and the treatment time was 2 minutes. The thickness of the oxide film after the alumite treatment was 1.5 μm.

( Reference Example 3)
The reference example 3 is different from the reference example 1 in that the composition of the heat insulating layer itself is the same and only the zircon oxidation treatment is performed on the painted surface of the aluminum plate to be coated. For this reason, only this chemical conversion treatment will be described here, and description of other steps will be omitted.

  First, zirconium nitrate (manufactured by Nippon Light Metal Co., Ltd.), hydrogen fluoride (manufactured by Wako Pure Chemical Industries, Ltd.), N-2 (aminoethyl) 3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-603), bis ( 2-hydroxyethyl) -3-aminopropyltriethoxysilane (manufactured by GELEST, SIB1140.0), zirconium concentration is 500 ppm, fluorine concentration is 420 ppm, alkoxysilane concentration containing amino group as solid content is 200 ppm, hydroxyl group is A chemical conversion treatment agent having an alkoxysilane concentration of 50 ppm was prepared. The pH of the chemical conversion treatment agent was adjusted to 2.8 using an aqueous sodium hydroxide solution. After adjusting the temperature of a chemical conversion treatment agent to 40 degreeC, the aluminum plate which is a to-be-processed agent was immersed in it for 60 second. The aluminum plate which was subjected to the chemical conversion treatment was spray-washed with tap water for 30 seconds. Subsequently, the aluminum plate was subjected to a spray water washing treatment for 10 seconds with ion-exchanged water.

Example 4
Example 4 differs from Reference Example 1 in that a linear siloxane having a fluoroalkyl group is added to the silicone resin. For this reason, only the process different from the reference example 1 is demonstrated here, and description of the process same as the reference example 1 is abbreviate | omitted.

First, hollow particles treated with a silane compound were obtained by the same method as in Reference Example 1.

  Next, in a reaction vessel equipped with a stirrer, a thermometer and a condenser, the concentration of a mixture of polytitanocarbosilane (47.4 wt%) and methylphenyl polysiloxane (52.6 wt%) was 45.7 70.0 g of a weight% xylene / 1-butanol solution (Tyrannovaris: Ube Industries, VN-100) was added, and 7.5 g of 1-butanol and hollow particles obtained as described above (super Balloon 732C: Showa Kagaku Kogyo Co., Ltd.) with a solid content of 32.0 g is added, and 1.7 g of trifluoropropyltrimethoxysilane (Shin-Etsu Chemical Co., Ltd.) is added as a chain siloxane having a fluoroalkyl group. They were uniformly dispersed by stirring for 24 hours. This obtained the coating material which is a heat insulating material which concerns on Example 4. FIG. The subsequent coating on the aluminum plate is the same as in Example 1. In addition, the thickness of the heat insulation layer obtained in Example 4 was 0.16 mm.

(Comparative Example 1)
In Comparative Example 1, unlike the above Reference Examples 1 to 3 and Example 4, the hollow particles were not treated with the silane compound.

  Specifically, in a reaction vessel equipped with a stirrer, a thermometer, and a condenser, the concentration of a mixture of polytitanocarbosilane (47.4 wt%) and methylphenyl polysiloxane (52.6 wt%) is 45. 70.0 g of a 7% by weight xylene / 1-butanol solution (Tyranwanis: Ube Industries, Ltd., VN-100) in a hollow form not treated with 7.5 g of 1-butanol and 32.0 g of a silane compound Particles (Super Balloon 732C: manufactured by Showa Kagaku Kogyo Co., Ltd.) were placed and stirred at room temperature for 24 hours to uniformly disperse them. This obtained the coating material which is the heat insulating material which concerns on the comparative example 1. FIG. The subsequent coating on the aluminum plate is the same as in Example 1. In addition, the thickness of the heat insulation layer obtained by the comparative example 1 was 0.14 mm.

For the heat insulating layers of Reference Examples 1 to 3, Example 4 and Comparative Example 1 obtained as described above, the initial appearance and oil resistance were evaluated.

  Specifically, as the initial appearance, the background color is an achromatic color of about N5 as defined in JIS Z 8721, and the illuminance of 300 lx or more is applied to the effective surface using ground glass transmitted light or diffused daylight of a light source other than a fluorescent lamp. The appearance of each heat insulating layer was visually observed at a distance of about 0.5 m, and the presence or absence of substrate exposure, swelling, peeling, cracking, see-through, repellency, pinholes, and yuzu was evaluated. As a result, as shown in [Table 2] above, no defects were recognized in any of the heat insulating layers.

Moreover, as an oil resistance test, after each heat insulation layer was immersed in the synthetic gasoline of room temperature for 60 minutes, the change of each film thickness and the presence or absence of melt | dissolution were measured. As a result, as shown in [Table 2] above, in the heat insulating layers of Reference Examples 1 to 3 and Example 4, no change in the film thickness and dissolution were observed. On the other hand, in the heat insulating layer of Comparative Example 1, changes in the film thickness and dissolution were observed. From these results, it was suggested that the oil resistance can be improved by treating the hollow particles with a silane compound and bonding the hollow particles and the silicone resin in the heat insulating layer.

DESCRIPTION OF SYMBOLS 1 Piston 2 Cylinder block 3 Cylinder head 4 Intake valve 5 Intake port 6 Exhaust valve 7 Exhaust port 8 Fuel injection valve 9 Cavity 10 Piston ring groove 11 Heat insulation layer 12 Hollow particle 13 Chemical conversion treatment layer

Claims (9)

A heat insulating structure in which a heat insulating layer is formed on the surface of a base material of a component constituting the engine combustion chamber,
The heat insulating layer includes a silicone resin and hollow particles,
The surface of the hollow particles is treated with an organic compound that can be covalently bonded to the silicone resin,
The silicone resin and the hollow particles are bound by the covalently bondable organic compound ,
The heat insulating structure for an engine combustion chamber member, wherein the heat insulating layer includes a chain siloxane having a fluoroalkyl group .   The heat insulation structure for an engine combustion chamber member according to claim 1, wherein the organic compound is a silane compound.   Reaction of alkoxyl group of main chain of silicone resin with alkyl group of silane compound, reaction of alkyl group of main chain of silicone resin with alkoxyl group of silane compound, and main chain of silicone resin The silicone resin and the hollow particles are indirectly bonded by a covalent bond formed by at least one of a reaction between the alkoxyl group of the silane compound and the alkoxyl group of the silane compound. The heat insulation structure of the engine combustion chamber member according to claim 2.   The engine according to any one of claims 1 to 3, wherein at least one of a chemical conversion treatment layer and an alumite treatment layer is provided between a base material surface of the component and the heat insulating layer. A heat insulation structure for a combustion chamber member. Insulating structure of the engine combustion chamber member according to any one of claims 1 to 4, characterized in that the SiO ₂ layer is formed on the surface of the heat insulating layer.   The heat insulation structure for an engine combustion chamber member according to any one of claims 1 to 4, wherein a plating layer is formed on a surface of the heat insulation layer. A method for manufacturing a heat insulating structure in which a heat insulating layer is formed on the surface of a base material of a component constituting an engine combustion chamber,
Treating the surface of the hollow particles with an organic compound capable of covalent bonding with a silicone resin;
Obtaining a heat insulating material obtained by mixing the silicone resin and the hollow particles;
Forming the heat insulating material on the surface of a base material of a component constituting the engine combustion chamber, and obtaining a heat insulating layer in which the silicone resin and the organic compound are covalently bonded;
With
The method for manufacturing a heat insulating structure for an engine combustion chamber member, wherein the heat insulating layer includes a chain siloxane having a fluoroalkyl group . The method for manufacturing a heat insulation structure for an engine combustion chamber member according to claim 7 , wherein a silane compound is used as the organic compound. Reaction of alkoxyl group of main chain of silicone resin with alkyl group of silane compound, reaction of alkyl group of main chain of silicone resin with alkoxyl group of silane compound, and main chain of silicone resin The method for producing a heat insulating structure for an engine combustion chamber member according to claim 8 , wherein a covalent bond is formed by at least one of a reaction between the alkoxyl group of the silane compound and the alkoxyl group of the silane compound.

Images