JPH08176445A - Room-temperature-curing organopolysiloxane composition excellent in adhesion to oily surface - Google Patents

Abstract

PURPOSE: To obtain a room-temperature-curing organopolysiloxane composition improved in adhesion to an oily surface by mixing a diorganopolysiloxane with an iminoxysilane or a condensate of its hydrolyzate, an organotin catalyst, an oil-absorbing carbon powder, a silane-modified polyoyalkylene, etc. CONSTITUTION: 100 pts.wt. organopolysiloxane having a hydroxyl group at each molecular terminal and having a viscosity (at 25 deg.C) of 250000-1000000cSt is mixed with about 1-25 pts.wt. iminoxysilane represented by formula I or II (wherein R<1> is a monovalent hydrocarbon group; R<2> and R<3> are each H or a monovalent hydrocarbon group; R<4> is a 2C or higher bivalent hydrocarbon group; and n is 3 or 4) (e.g. methyltributanoxime silane) or condensate of its hydrolyzate. The obtained mixture is further mixed with about 0.1-10 pts.wt. organotin catalyst (e.g. dibutyltin dilaurate), about 10-50 pts.wt. oil-absorbing carbon powder, such as carbon black having a mean particle diameter of 60μm or below and a DBP absorption of 80ml/100g or above, and about 0.1-15 pts.wt. silane-modified polyoxyalkylene and/or polyether-modified polysiloxane, and the resulting mixture is further mixed in a dry atmosphere to obtain a room- temperature-curing organopolysiloxane composition.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a condensation curing type room temperature curable organopolysiloxane composition.
In particular, the present invention relates to a room temperature curable organopolysiloxane composition capable of forming a cured product exhibiting good adhesiveness even to a substrate having an oily substance such as machine oil and engine oil attached to its surface.

[0002]

2. Description of the Related Art Conventionally, oil-resistant gaskets and packing materials made of cork, organic rubber, asbestos, etc. have been used as seal materials around the engine of automobiles. However, there are disadvantages such as the inconvenience of inventory management, the complicated mounting work process, and the unreliable sealing performance. For this reason, FIPG (Formed in Place Gaskets), which uses an organopolysiloxane composition curable at room temperature, is now used as this type of sealing material. This curable composition has good workability, and the formed rubber elastic body cured product has excellent properties such as hermeticity and heat resistance, and is highly evaluated.

[0003]

However, the conventionally known room temperature curable organopolysiloxane composition has a drawback that the cured product formed does not have sufficient adhesion to the oil surface. For example, oily substances such as machine oil and engine oil inevitably adhere to these molded products at the time of molding into an engine block, an oil pan, or punching. Also,
Engine oil or the like may be injected into the engine block at a stage before the curable composition is completely cured after being applied to the engine block. Therefore, since these oily substances are present on the adhesive surface between the curable composition and the engine block, there arises a problem that the cured product which functions as a sealant has poor adhesion.

The above problem can be solved to some extent by completely cleaning the adhesive surface. However, such a cleaning operation requires a considerable amount of time.
It is difficult to make this engine assembly process as usual.

On the other hand, as a room temperature curable organopolysiloxane composition in which the adhesion to the oil surface is improved to some extent, a composition in which an oil absorbing carbon powder is blended as a filler has been proposed. However, even in the case of this composition, it has not been possible to form a cured product in which the adhesiveness to the oil surface is improved to a satisfactory level, and particularly when the amount of the oily substance remaining on the adhesive interface becomes large, the adhesiveness rapidly increases. There is still room for improvement in terms of loss.

Therefore, an object of the present invention is to provide a room temperature curable organopolysiloxane composition which can form a cured product having excellent adhesion to oil surfaces and which can be effectively used as a sealant around the engine of an automobile. To provide.

[0007]

According to the present invention, (A) has hydroxyl groups at both ends of the molecular chain and has a viscosity at 25 ° C. of 25 to 1,000,
000 cSt diorganopolysiloxane, (B) the following general formula (1) or (2):

Embedded image

[Chemical 4] In the formula, R ¹ is an unsubstituted or substituted monovalent hydrocarbon group, R 1
² and R ³ may be the same or different, and a hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group, R ⁴ is
An unsubstituted or substituted divalent hydrocarbon group having 2 or more carbon atoms, n is 3 or 4, an iminoxysilane, a partial hydrolysis-condensation product thereof or a mixture thereof, (C) organotin -Based catalyst, (D) average particle size of 60 nm or less, BET specific surface area of 30 m ² / g or more, and DBP oil absorption (JIS K 6221) of 80 ml / 100 g or more, and (E) silane-modified polyoxy At least one alkylene or polyether modified polysiloxane
An organopolysiloxane composition containing a seed and having excellent oil surface adhesion is provided.

In the composition of the present invention, the oil-absorbing carbon powder of component (D), which is blended as a filler, adsorbs and removes the oily substance present on the adhesive interface. Further, the silane-modified polyoxyalkylene or polyether-modified polysiloxane as the component (E) exhibits good affinity to both the oily substance and the diorganopolysiloxane as the component (A) as the base polymer. As a result of this,
It is possible to form a cured product having good adhesiveness even at the interface where an oily substance is present.

Component (A) Component (A), the diorganopolysiloxane, is a base polymer and has hydroxyl groups at both ends of the molecular chain. This diorganopolysiloxane is represented by the following general formula (3):

Embedded image In the formula, R is an unsubstituted or substituted monovalent hydrocarbon group,
p is a positive integer.

In the above general formula (3), the monovalent hydrocarbon group R is, for example, an alkyl group having 1 to 6 carbon atoms such as a methyl group, an ethyl group, a propyl group or a butyl group,
Cycloalkyl group having 6 to 12 carbon atoms such as cyclohexyl group, 2 to 8 carbon atoms such as vinyl group and allyl group
Alkenyl groups, phenyl groups, tolyl groups and other aryl groups having 6 to 12 carbon atoms, benzyl groups, phenylethyl groups and other aralkyl groups having 7 to 12 carbon atoms, and at least some of the hydrogen atoms of these groups A group in which is substituted with a halogen atom, a cyano group or the like, for example, a chloromethyl group, a trifluoropropyl group, a cyanoethyl group and the like can be mentioned.
p is an integer indicating the degree of polymerization of this diorganopolysiloxane. This diorganopolysiloxane has a viscosity at 25 ° C. of 25 to 1,000,000 cSt, preferably 1,000 to 100,000 cS, from the viewpoint of workability and mechanical strength of the cured product.
Since it is within the range of t, p is generally an integer of 10 or more.

Component (B) Component (B) is a cross-linking agent, and at least one of iminoxysilane represented by the general formula (1) or (2) or a partial hydrolysis-condensation product thereof is used. In the general formulas (1) and (2), as the unsubstituted or substituted monovalent hydrocarbon group R ¹ , the same groups as R in the general formula (3) can be exemplified, which are preferable. Have 1 to 10 carbon atoms, especially 1 to 8 carbon atoms. R ² and R ³ are a hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group, and examples of the monovalent hydrocarbon group are the same as R in the general formula (3) as described above. can do. In the present invention, preferred as R ² and R ³ are alkyl groups, and among them, those having 1 to 6 carbon atoms are preferred. R ⁴ which forms a ring with the carbon atom to which the nitrogen atom is bonded is an unsubstituted or substituted divalent hydrocarbon group having 2 or more carbon atoms, and generally an alkylene group is suitable. , Especially those having 5 to 8 carbon atoms,
For example, a pentylene group, a hexylene group, a 2-methylhexylene group, and a 2-ethylhexylene group. Further, n is a number of 3 or 4. Therefore, the iminoxysilane represented by the general formula (1) or (2) has at least three iminoxy groups which are hydrolyzable groups, and thereby acts as a cross-linking agent for the component (A) to give a rubber. A cured product of an elastic body is formed.

The iminoxysilane represented by the above general formula (1) is not limited to this, but examples thereof include methyltri (butanoxime) silane, vinyltri (butanoxime) silane, phenyltri (butanoxime) silane and propyltri (butanoxime). ) Silane, tetra (butanoxime) silane, 3,3,3-tolufluoropropyltri (butanoxime) silane, 3-chloropropyltri (butanoxime) silane, 3-chloropropyltri (butanoxime) silane, methyltri (propanoxime) silane, Methyltri (pentanoxime) silane,
Methyltri (isopentanoxime) silane etc. can be illustrated. Of these, methyltributanoxime silane and vinyltributanoxime silane are preferable.

Examples of the iminoxysilane represented by the general formula (2) include vinyltri (cyclopentanoxime) silane and methyltri (cyclohexanoxime) silane.

In the present invention, the component (B) acting as a cross-linking agent is the iminoxysilane represented by the above general formula (1) or (2) used alone or in combination of two or more kinds. Of course, it is also possible to use siloxanes obtained by partial hydrolysis of these iminoxysilanes and consequent condensation. This siloxane may have a linear, branched, or cyclic molecular structure.

The above-mentioned component (B) is generally 1 to 25 parts by weight, especially 4 parts by weight per 100 parts by weight of the component (A).
Used in an amount of ~ 15 parts by weight. If it is less than 1 part by weight, gelation may occur during production or storage of the curable composition,
Further, the cured elastic body obtained from the curable composition may not exhibit the desired physical properties. Further, if it is used in an amount of more than 25 parts by weight, the curing shrinkage of the curable composition at the time of curing tends to increase, and the elasticity of the cured product tends to decrease.

Component (C) The organotin-based catalyst of component (C) is composed of the above-mentioned components (A) and (B).
It is used to accelerate the curing of the ingredients,
The organotin compound used in this type of condensation-curing type silicone rubber composition is used. Examples thereof include alkyltin ester compounds such as dibutyltin diacetate, dibutyltin dilaurate, and dibutyltin dioctoate, tin halide compounds, tin orthoester compounds, and the like. Particularly preferred are reactivity and ease of handling. Is an alkyl tin ester compound.

This organotin catalyst is the same as the component (A) 10
It is used in an amount of 0.01 to 10 parts by weight, especially 0.1 to 1 part by weight, per 0 parts by weight. If it is less than 0.01 parts by weight, it takes a long time to form a tack-free film when this curable composition is exposed to the air, and its internal curability also deteriorates. Further, when it is used in an amount of more than 10 parts by weight, the coating film forming time is shortened to several tens of seconds and workability is lowered, and the heat resistance of the obtained cured product tends to be lowered.

Component (D) The oil-absorbing carbon powder of component (D) is used to adsorb and remove oily substances such as engine oil existing at the adhesive interface, and for this reason, the average particle size is A fine powder having a diameter of 60 nm or less, preferably 50 nm or less, and BE
T specific surface area of 30 m ² / g or more, preferably 50 m ² /
g or more, DBP oil absorption (according to JIS-K-6221 rubber carbon black test method) of 80 ml / 100 g or more, preferably 130 ml / 100 g or more is used.

Specific examples of the oil absorbing carbon powder having such physical properties include porous carbon powder such as activated carbon, carbon black such as Ketjen black, channel black, furnace black and acetylene black. These are used alone or in combination of two or more.

The oil-absorbing carbon powder is generally used in an amount of 10 to 50 parts by weight, preferably 20 to 40 parts by weight, per 100 parts by weight of the component (A). If the amount is too small, the oily substance cannot be effectively adsorbed and removed, and the adhesiveness of the cured product decreases. On the other hand, if the amount is too large, the curability of the curable composition may be deteriorated, and the suitability as a FIPG material may be deteriorated.

Component (E) The silane-modified polyoxyalkylene and polyether-modified polysiloxane used as component (E) are (A)
Since it has both a silane or siloxane moiety having a high affinity for the diorganopolysiloxane of the component and a polyether moiety having a high affinity for the oily substance, the component (D) dispersed in the composition is The affinity between the oil-absorbent carbon powder surface and the oil substance adhering to the adhesive interface is increased, and the oil absorbency of the carbon powder is satisfactorily exhibited.

As the silane-modified polyoxyalkylene, for example, the following formula (4):

[Chemical 6] In the formula, R ⁵ is an unsubstituted or substituted monovalent hydrocarbon group, R 5
⁶ is an unsubstituted or substituted divalent hydrocarbon group, X is a hydrolyzable group, m is an integer of 0 to 2, and has a silyl group represented by in the molecular chain, particularly at the terminal of the molecular chain. I can list things.

In the above formula (4), examples of the unsubstituted or substituted monovalent hydrocarbon group R ⁵ include the same groups as R in the above general formula (3), and particularly preferred ones are A methyl group and a vinyl group. Divalent hydrocarbon group R ⁶
Suitable examples of the alkylene group having 1 to 10 carbon atoms such as methylene group, ethylene group, propylene group and decene group, and the following formula: --CH ₂ CH ₂ --C ₆ H ₄ --CH _2- Mention may be made of aromatic-containing groups. In general,
Alkylene groups are suitable.

Examples of the hydrolyzable group X include alkenyloxy groups such as propenyloxy group and isobutenyloxy group, ketoxime groups such as dimethylketoxime group and methylethylketoxime group, methoxy group, ethoxy group and butoxy group. Alkoxy groups, N-butylamino groups, N, N-diethylamino groups and other amino groups, N,
Examples thereof include aminoxy groups such as N-diethylaminoxy group and amide groups such as N-methylacetamide group. When two or more R ⁵ and X are present, they may be the same or different.

The alkylene oxide unit constituting the main chain of the silane-modified polyoxyalkylene has 2 to 4 carbon atoms, for example, -CH ₂ CH ₂ O-, -CH ₂ CH (CH ₃ ) O-,
_{-CH 2 CH (CH 2 CH 3} ) O -, - CH 2 CH 2 C
H ₂ CH ₂ O-, and the like. This main chain may be composed of only one kind of these structural units, or may be composed of two or more kinds of structural units. A particularly preferred structural _{units, -CH 2 CH (CH 3)} O- and the like. The structure of this polyoxyalkylene molecular chain may be linear, branched, cyclic, or a combination of these structures. Further, the molecular weight is not particularly limited, but in view of easy availability, it is usually 500 to 20,
It is in the range of 000.

The above-mentioned silane-modified polyoxyalkylene is produced, for example, by subjecting a polyoxyalkylene polymer having unsaturated groups at both ends to hydrogensilane having a corresponding hydrolyzable group in the presence of a platinum catalyst. be able to.

The polyether-modified polysiloxane has, for example, the following formula (5):

[Chemical 7] Wherein, Me is a methyl group, A and B are groups represented by methyl group or R ^7, R ⁷ is represented by the following _{^{formula: -R 8 (CH 2 CH 2}} O) a (CH 2 CH (CH 3)
O) _b R ⁹ (wherein R ⁸ is an unsubstituted or substituted divalent hydrocarbon group, R 8
⁹ is an unsubstituted or substituted monovalent hydrocarbon, a and b are each an integer of 0 to 20 and a + b ≧ 1, and q and r are each an integer of 0 to 100. Yes,
When q = 0, A and / or B is represented by R ⁷ .

In the above general formula (5), R ⁸ is preferably an alkylene group, particularly one having 1 to 3 carbon atoms. Examples of R ⁹ include the same groups as those exemplified for R in the general formula (3), and preferably a methyl group, an ethyl group or a propyl group.

The above-mentioned polyether-modified polysiloxane can be produced, for example, by subjecting a polyether polymer having an unsaturated group at one end and a corresponding hydrogen siloxane to an addition reaction in the presence of a platinum catalyst.

The component (E) is the component (A) 100 described above.
It is preferably used in an amount of 0.1 to 15 parts by weight, particularly 0.5 to 10 parts by weight, per part by weight. When the amount is too small, the absorbability of the oily substance of the curable composition is low, so that the oil surface adhesiveness of the cured product is lowered, while when the amount is too large, the composition of the component (E) during storage of the curable composition is low. Separation from objects may occur.

Other components In the curable composition of the present invention, in addition to the above-mentioned components (A) to (E), the curable composition of the present invention may be used in the range not impairing the oil surface adhesiveness.
Various conventionally known additives used in this type of composition can be added. Such additives include, for example, reinforcing agents such as fumed silica, precipitated silica, quartz powder, carbon powder, talc and bentonite; fibrous fillers such as asbestos, glass fibers, carbon fibers and organic fibers; calcium carbonate. , Basic fillers such as zinc carbonate, zinc oxide, magnesium oxide and celite; heat resistance improvers such as red iron oxide and cerium oxide; cold resistance improvers;
Dehydrating agents; anticorrosive agents; adhesion improving agents such as γ-glycidoxypropyltrimethoxysilane; liquid reinforcing agents such as reticulated polysiloxanes composed of triorganosiloxy units and SiO ₂ units.

Curable Composition The composition of the present invention is prepared by uniformly mixing predetermined amounts of the essential components (A) to (E) and various additives, if necessary, in a dry atmosphere. Obtained as a liquid type room temperature curable composition. When this composition is exposed to the air, a crosslinking reaction proceeds due to moisture in the air to form a cured product of a rubber elastic body. Since this composition has excellent absorbability of an oily substance, even if the oily substance is attached to the surface on which the composition is applied, a cured product that is well adhered to the surface can be formed. Therefore, this curable composition,
Particularly, it is useful as a room temperature curing type organopolysiloxane composition for FIPG system in engine assembly.

[0033]

EXAMPLES In the following specific examples, "part" means part by weight, and viscosity means a value measured at 25 ° C.

Comparative Example 1 Dimethylpolysiloxane (viscosity: 5,000 cSt) with both ends of the molecular chain blocked with hydroxyl groups 100 parts Vinyltributanoxime silane 10.0 parts Dibutyltin dioctoate 0.1 parts Average particle size 53 nm, ratio A curable composition was prepared by mixing 20 parts of acetylene black having a surface area of 32 m ² / g and a DBP oil absorption of 180 ml / 100 g and 3.0 parts of fumed silica in an anhydrous state.

A sheet having a thickness of 2 mm was made from the above composition and left for 7 days in an atmosphere of 20 ° C. and 55% RH to give a rubber elastic body, and its rubber physical properties were examined according to JIS-K-6301. .
Table 1 shows the results. Further, in order to confirm the oil surface adhesiveness, a peel adherend was prepared by the following method using the curable composition prepared above, and left in an atmosphere of 20 ° C. and 55% RH for 7 days. As a rubber elastic body, 180 degree peel adhesion force and cohesive failure rate were measured, and the results are also shown in Table 1. (Preparation of peel adherend) JIS-G-31 washed with toluene
Plate-shaped adherend made of an iron plate that conforms to 41 (100 × 25 × 2m
m) was coated with engine oil so that the amount of oil adhered was 0.2 g / cm ^2, and then the curable composition of the sample was applied to a thickness of 1 mm.
It is applied to the above, and a stainless wire mesh (200 × 25 mm) is adhered on it to make a peel adherend, and the above-mentioned 20 ° C., 55% RH × 7
After curing under day conditions, measure the peel adhesion strength with JIS
-Proceeded according to K6854.

Comparative Example 2 Instead of the acetylene black used in Comparative Example 1, DB was used.
P oil absorption 30ml / 100g, average particle size 50nm, specific surface area 40
except for using 20 parts of graphite powder is m ² / g was prepared a curable composition in the same manner as in Comparative Example 1. This curable composition had a thickness of 2 as in Comparative Example 1.
mm sheets were prepared, the physical properties of the rubber were measured, and the 180 ° peel adhesion force and cohesive failure rate were measured to confirm the oil surface adhesiveness. The results are shown in Table 1.

[0037] Example 1 0.5 parts of alpha, .omega.-bis except for further using (methyl diisopropoxy silyl ethyl) polypropylene oxide, to prepare a curable composition in the same manner as in Comparative Example 1. This curable composition had a thickness of 2 as in Comparative Example 1.
mm sheets were prepared, the physical properties of the rubber were measured, and the 180 ° peel adhesion force and cohesive failure rate were measured to confirm the oil surface adhesiveness. The results are shown in Table 1.

Example 2 A curable composition was prepared in the same manner as in Comparative Example 1 except that 1.0 part of α, ω-bis (methyldimethoxysilylethyl) polypropylene oxide was further used. For this curable composition, a sheet having a thickness of 2 mm was prepared in the same manner as in Comparative Example 1, the rubber physical properties thereof were measured, and the 180 ° peel adhesion force and cohesive failure rate were measured in order to confirm the oil surface adhesiveness. did. The results are shown in Table 1.

Example 3 Comparative Example 1 except that 1.0 part of α, ω-bis (trimethoxysilylethyl) polypropylene oxide was additionally used.
A curable composition was prepared in the same manner as in. For this curable composition, a sheet having a thickness of 2 mm was prepared in the same manner as in Comparative Example 1, the rubber physical properties thereof were measured, and the 180 ° peel adhesion force and cohesive failure rate were measured in order to confirm the oil surface adhesiveness. did. The results are shown in Table 1.

Example 4 A curable composition was prepared in the same manner as in Comparative Example 1 except that 1.0 part of α, ω-bis (methyldimethoxysilylethyl) polybutylene oxide was further used. For this curable composition, a sheet having a thickness of 2 mm was prepared in the same manner as in Comparative Example 1, the rubber physical properties thereof were measured, and the 180 ° peel adhesion force and cohesive failure rate were measured in order to confirm the oil surface adhesiveness. did. The results are shown in Table 1.

[0041]

[Table 1] The hardness was measured using a JIS-K-6301 type A spring type tester.

Comparative Example 3 Dimethylpolysiloxane with both ends of the molecular chain blocked with hydroxyl groups (viscosity: 20,000 cSt) 100 parts Methyltributanoxime silane 11.0 parts Dibutyltin dilaurate 0.2 parts Average particle size 30 nm, specific surface area 800 m ² / and 10 parts of Ketjen Black having a DBP oil absorption of 360 ml / 100 g were mixed in an anhydrous state to prepare a curable composition. This curable composition had a thickness of 2 mm as in Comparative Example 1.
Sheet was prepared, its rubber physical properties were measured, and the 180 degree peel adhesion force and cohesive failure rate were measured to confirm the oil surface adhesiveness. Table 2 shows the results.

Comparative Example 4 Instead of Ketjen Black used in Comparative Example 3, DB
P oil absorption 65ml / 100g, average particle size 50nm, specific surface area 15
A curable composition was prepared in the same manner as in Comparative Example 3 except that 10 parts of furnace black having m ² / g was used. This curable composition had a thickness of 2 as in Comparative Example 3.
mm sheets were prepared, the physical properties of the rubber were measured, and the 180 ° peel adhesion force and cohesive failure rate were measured to confirm the oil surface adhesiveness. Table 2 shows the results.

[0044] Example 5 the following formula _{Me 3 SiO (Me 2 SiO)} 10 {Me (MeOC 2 H 4 OC 2 H 4 OC 3 H
_A curable composition was prepared in the same manner as in Comparative Example 3 except that 10 parts of the polyether-modified polysiloxane represented by ₆ ) SiO} ₅ SiMe ₃ was further used. For this curable composition, a sheet having a thickness of 2 mm was prepared in the same manner as in Comparative Example 3, the physical properties of the rubber were measured, and the 180 ° peel adhesion force and cohesive failure rate were measured to confirm the oil surface adhesiveness. did. These results are shown in Table 2.
It was shown to.

Example 6 The following formula: {(BuOCH ₂ CH (Me) OCH ₂ CH (Me) OCH ₂ CH (Me) OCH ₂ ) Me
_A curable composition was prepared in the same manner as in Comparative Example 3 except that 10 parts of the polyether-modified polysiloxane represented by ₂ SiO ₂ } (Me ₂ SiO) ₅₀ was further used. For this curable composition, a sheet having a thickness of 2 mm was prepared in the same manner as in Comparative Example 3, the physical properties of the rubber were measured, and the 180 ° peel adhesion force and cohesive failure rate were measured to confirm the oil surface adhesiveness. did. These results are shown in Table 2.
It was shown to.

Example 7 The following formula: Me ₃ SiO (Me ₂ SiO) ₁₀ [Me {MeO (C ₂ H ₄ O) ₉ C ₃ H ₆ }
A curable composition was prepared in the same manner as in Comparative Example 3 except that 10 parts of the polyether-modified polysiloxane represented by [SiO 2] ₅ SiMe ₃ was further used. For this curable composition, a sheet having a thickness of 2 mm was prepared in the same manner as in Comparative Example 3, the physical properties of the rubber were measured, and the 180 ° peel adhesion force and cohesive failure rate were measured to confirm the oil surface adhesiveness. did. These results are shown in Table 2.
It was shown to.

Example 8 The following formula: Me ₃ SiO [Me {MeO (CH ₂ CHMeO) ₂₅ C ₃ H ₆ } SiO] ₃₄ Si
A curable composition was prepared in the same manner as in Comparative Example 3 except that 10 parts of the polyether-modified polysiloxane represented by Me ₃ was further used. For this curable composition, a sheet having a thickness of 2 mm was prepared in the same manner as in Comparative Example 3, the physical properties of the rubber were measured, and the 180 ° peel adhesion force and cohesive failure rate were measured to confirm the oil surface adhesiveness. did. These results are shown in Table 2.
It was shown to.

[0048]

[Table 2]

[0049]

EFFECTS OF THE INVENTION The curable composition of the present invention has a high absorbability of oily substances, and even when oily substances such as engine oil adhere to the surface of the substrate to which this composition is applied, It is possible to form a hardened product with strong adhesion.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display area C08L 83:12)

Claims (2)

[Claims] 1. (A) having hydroxyl groups at both ends of the molecular chain, at 25 ° C.
A diorganopolysiloxane having a viscosity at 25-1,000,000 cSt, (B) the following general formula (1) or (2): Embedded image In the formula, R ¹ is an unsubstituted or substituted monovalent hydrocarbon group, R ² and R ³ may be the same or different, and a hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group, R ⁴ is , An unsubstituted or substituted divalent hydrocarbon group having 2 or more carbon atoms, n is 3 or 4, an iminoxysilane, a partial hydrolysis-condensation product thereof, or a mixture thereof, (C) organic Tin-based catalyst, (D) Average particle size 60 nm or less, BET specific surface area 30 m ² /
g or more, and DBP oil absorption (JIS K 6221) is 80 ml /
A room-temperature-curable organopolysiloxane composition having excellent oil surface adhesion, which comprises 100 g or more of oil-absorbent carbon powder and (E) at least one of silane-modified polyoxyalkylene and polyether-modified polysiloxane. 2. A method for producing a cured product, which comprises curing the composition according to claim 1.