Water-resistant adhesive polyorganosiloxane composition

Abstract

Provided are: a curable polyorganosiloxane composition that contains (a) a polyorganosiloxane having, per molecule, 2 or more curable functional groups able to bring about an addition reaction, (b) a crosslinking agent having, per molecule, 3 or more crosslinking groups able to react with a curable functional group in the component (a), (c) a curing catalyst able to catalyze a crosslinking reaction between the components (a) and (b), (d) a silicon compound in which a monovalent alkyl group having 8-30 carbon atoms and a hydrolyzable group are directly bonded to a silicon atom; and, optionally, (e) flaky inorganic fine particles; and an adhesive which is obtained using the curable polyorganosiloxane composition and which exhibits improved adhesive durability to a variety of substrates at sites in contact with aqueous solutions (water, LLC, salt water, and the like).

Description

[Technical field]

[0001] The present invention relates to a water-resistant adhesive polyorganosiloxane composition. [Background technology]

[0002] Various curable polyorganosiloxane compositions that produce rubber-like elastomers are known as materials that can be used as adhesives. Polyorganosiloxane compositions are broadly classified into addition curing type and moisture curing type depending on the mechanism of the curing reaction. Addition reaction curing type polyorganosiloxane compositions are cured by irradiation with light or heating at room temperature or about 40 ° C to 150 ° C to exhibit adhesion to various adherends. Patent Document 1 proposes an adhesive polyorganosiloxane composition containing a zirconium compound and a specific adhesion imparting agent (JP Patent Publication No. 2019-151695).

[0003] One of the applications in which polyorganosiloxanes are in high demand as adhesives is in aircraft and automobile applications. In the aircraft and automobile industries and related electronic materials fields, the demand for addressing global environmental issues and reducing size and weight is increasing year by year, and replacement of metals such as iron and aluminum with plastic materials is being considered. For this reason, when using polyorganosiloxane compositions as adhesives, adhesion to various substrates is required, and materials are being considered (JP Patent Publication No. 2003-221506, JP Patent Publication No. 2016-199687).

[0004] In addition, in automotive applications, the adhesive site comes into contact with antifreeze such as engine oil or LLC liquid, and is exposed to harsh conditions due to heat. For this reason, oil resistance and little deterioration of physical properties are also required characteristics of adhesives (JP 2003-183504 A, JP 2003-327829 A, JP 2015-067647 A). Polyorganosiloxane compositions are also used to solve the problem of lack of reliability, which was one of the problems with organic rubbers and the like that were previously used. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2019-151695 A [Patent Document 2] JP 2003-221506 A [Patent Document 3] JP 2016-199687 A [Patent Document 4] JP 2003-183504 A [Patent Document 5] JP 2003-327829 A [Patent Document 6] JP 2015-067647 A Summary of the Invention [Problem to be solved by the invention]

[0006] In automotive applications, adhesives are often exposed to weather as well as harsh environments involving heating. Therefore, adhesives are required to have water resistance to improve their reliability. In particular, adhesives are required to maintain adhesion over long periods of time, such as several years. However, existing products do not yet have sufficient water resistance. In some cases, peeling or corrosion may occur in an environment where the adhesive is immersed in water. The present inventors have found that with conventional adhesives, phenomena such as peeling from the adhesive portion occur in water resistance tests (immersion tests with the bonded substrate), and this is particularly noticeable in accelerated tests in warm water. Since long term reliability is a safety factor in aircraft and automotive applications, there is a strong demand for improving the water resistance of adhesives, especially over long periods of time.

[0007] An object of the present invention is to provide an adhesive that has improved adhesion durability to various substrates in the area that comes into contact with aqueous solutions (water, LLC, salt water, etc.). [Means for solving the problem]

[0008] According to the inventors' investigation, it was found that the cause of peeling or corrosion of the adhesive by water is thought to be the penetration of moisture between the adhesive and the substrate, which causes the bond at the bonded portion to be broken, resulting in a decrease in adhesion. In order to prevent this, it is effective to increase the distance that water penetrates, or to perform hydrophobization to prevent the penetration of water itself. In order to solve this problem in addition-curing adhesives, the inventors have found that adding a silane compound having a long-chain alkyl group is effective. Effect of the Invention

[0009] The present invention provides a polyorganosiloxane composition that can be used as an adhesive and has improved adhesion durability to various substrates in the area in contact with aqueous solutions (water, LLC, salt water, etc.). That is, the present invention relates to the following [1] to [9]. [1] (a) A polyorganosiloxane having two or more curable functional groups capable of undergoing an addition reaction in one molecule; (b) a crosslinking agent having three or more crosslinking groups in one molecule that are reactive with the curable functional group of (a); (c) a curing catalyst capable of catalyzing the crosslinking reaction of (a) and (b); and (d) silicon compounds having a monovalent alkyl group having 8 to 30 carbon atoms and a hydrolyzable group directly bonded to a silicon atom; 1. A curable polyorganosiloxane composition comprising: [2] The curable polyorganosiloxane composition according to [1], wherein (a) is a polyorganosiloxane having two or more alkenyl groups in one molecule, and (c) is a platinum compound. [3] The curable polyorganosiloxane composition according to [1] or [2], further comprising (e) scaly inorganic fine particles in an amount of 10 to 500 parts by mass per 100 parts by mass of the total of the (a) to (d) components. [4] The curable polyorganosiloxane composition according to [3], wherein the scaly inorganic fine particles contain silica, a silicate mineral, or a mixture thereof. [5] The (d) silicon compound having a monovalent alkyl group having 8 to 30 carbon atoms and a hydrolyzable group directly bonded to a silicon atom is represented by the following formula: R 1 n Si(OR 2 ) 4-n (In the formula, R 1 is a monovalent alkyl group having 8 to 30 carbon atoms, and R 2 is hydrogen or an alkyl group having 1 to 6 carbon atoms, and n is an integer of 1 to 3. [6] The curable polyorganosiloxane composition according to any one of [1] to [5] above, wherein the (d) silicon compound having a monovalent alkyl group having 8 to 30 carbon atoms and a hydrolyzable group directly bonded to a silicon atom has a monovalent alkyl group having 8 to 20 carbon atoms. [7] The curable polyorganosiloxane composition according to any one of [1] to [6] above, wherein the (d) silicon compound having a monovalent alkyl group having 8 to 30 carbon atoms and a hydrolyzable group directly bonded to a silicon atom is contained in an amount of 0.01 to 10.0 parts by mass per 100 parts by mass of the entire composition. [8] The curable polyorganosiloxane composition according to any one of the above [1] to [7], further comprising an adhesion promoter. [9] An adhesive comprising the curable polyorganosiloxane composition according to any one of [1] to [8] above. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present invention relates to a curable polyorganosiloxane composition comprising: (a) a polyorganosiloxane having two or more curable functional groups in one molecule capable of undergoing an addition reaction; (b) a crosslinking agent having three or more crosslinking groups in one molecule that are reactive with the curable functional group of (a); (c) a curing catalyst capable of catalyzing the crosslinking reaction of (a) and (b); and (d) a silicon compound having a monovalent alkyl group having 8 to 30 carbon atoms and a hydrolyzable group directly bonded to a silicon atom; and optionally further comprising (e) inorganic fine particles. The composition of the present invention will be described in detail for each item below. In this specification, the term "to" indicating a range of values ​​is used to mean that the values ​​before and after the range are included as the lower and upper limits.

[0011] As used herein, "organic group" refers to a group containing carbon. The valence of an organic group is indicated by describing it as "n-valent", where n is any natural number. Thus, for example, a "monovalent organic group" refers to a carbon-containing group having only one bond. The bond may be possessed by an element other than carbon. Even if the valence is not specifically stated, a person skilled in the art can grasp the appropriate valence from the context.

[0012] As used herein, the term "hydrocarbon group" refers to a group containing carbon and hydrogen, with at least one hydrogen atom being removed from the molecule. Such a hydrocarbon group is not particularly limited, and may be substituted with one or more substituents, and may include a hydrocarbon group having 1 to 20 carbon atoms, such as an aliphatic hydrocarbon group or an aromatic hydrocarbon group. The above-mentioned "aliphatic hydrocarbon group" may be linear, branched, or cyclic, and may be saturated or unsaturated. The hydrocarbon group may also contain one or more ring structures. The hydrocarbon group may have one or more heteroatoms or structures containing heteroatoms, such as nitrogen atoms (N), oxygen atoms (O), sulfur atoms (S), silicon atoms (Si), amide bonds, sulfonyl bonds, siloxane bonds, carbonyl groups, and carbonyloxy groups, at its terminal or in the molecular chain.

[0013] As used herein, examples of the substituents of the "hydrocarbon group" include, but are not limited to, halogen atoms; C 1-6 Alkyl group, C 2-6 Alkenyl group, C 2-6 Alkynyl group, C 3-10 Cycloalkyl groups, C 3-10Unsaturated cycloalkyl groups, 5-10 membered heterocyclyl groups, 5-10 membered unsaturated heterocyclyl groups, C 6-10 Examples of the group include groups selected from aryl groups and 5- to 10-membered heteroaryl groups.

[0014] In this specification, alkyl groups and phenyl groups may be unsubstituted or substituted unless otherwise specified. Substituents for such groups are not particularly limited, but include, for example, halogen atoms, C 1-6 Alkyl group, C 2-6 Alkenyl groups and C 2-6 alkynyl groups.

[0015] Ingredient (a) The curable polyorganosiloxane composition of the present invention contains, as component (a), at least one polyorganosiloxane having two or more curable functional groups capable of undergoing an addition reaction in one molecule. Component (a) functions as a base polymer of the curable polyorganosiloxane composition. Here, the term "curable functional group" refers to a functional group capable of undergoing a curing reaction, and in the present invention, refers to a functional group that undergoes an addition reaction. Each curable functional group is preferably the same functional group, but different types of functional groups can be mixed in the same molecule as long as they are functional groups that undergo an addition reaction. The curable functional group can be present at any position of the polyorganosiloxane molecule. For example, in the case of a linear polyorganosiloxane, the curable functional group may be present at the molecular end, or may be present as a side chain at a site other than the end. In the case of a linear polyorganosiloxane, at least one curable functional group is preferably present at each end of the molecular main chain of component (a). In this specification, the molecular main chain of component (a) refers to the relatively longest bonding chain in the molecule of component (a).

[0016] The molecular skeleton of component (a) is not particularly limited as long as the siloxane bond is the main skeleton. The siloxane skeleton may be interrupted by a divalent organic group. Herein, in the description of the structure of the siloxane compound, the structural units of the siloxane compound may be described by the following abbreviations. Hereinafter, these structural units may be referred to as "M unit", "D unit", etc. M: -Si(CH3)3O 1 / 2 M H :-SiH(CH3)2O 1 / 2 M Vi :-Si(CH=CH2)(CH3)2O 1 / 2 D: Si(CH3)2O 2 / 2 D H :SiH(CH3)O 2 / 2 T: Si(CH3)O 3 / 2 Q:SiO 4 / 2 Hereinafter, in this specification, the siloxane compound is constructed by combining the above structural units, but may at least partially contain those in which the methyl groups of the above structural units are replaced with other groups, such as halogens such as fluorine, or hydrocarbon groups such as phenyl groups. H 20 D 20 If you write, D H It is not intended that 20 units are followed by 20 D units, and it is understood that each unit may be arranged arbitrarily. The siloxane compound can have various three-dimensional structures due to the T units or Q units. Therefore, component (a) can have any molecular skeleton such as a linear, branched, cyclic, or a combination of these structures. Component (a) preferably has a linear molecular skeleton.

[0017] In one embodiment of the present invention, component (a) is not particularly limited as long as it has an average of two or more alkenyl groups bonded to silicon atoms in one molecule and can form a network structure by addition reaction with a hydrosilyl group (Si-H group) of (b) described later. Representative examples of component (a) include those represented by the general formula (I): (R 1 ) a (R 2 ) b SiO (4-a-b) / 2 (I) (In the formula, R 1 is an alkenyl group; R 2 is a monovalent hydrocarbon group having no aliphatic unsaturated bonds; a is an integer from 1 to 3; b is an integer of 0 to 2, with the proviso that a+b is an integer of 1 to 3. The compound has at least two alkenyl-containing siloxane units represented by the following formula (1):

[0018] One specific example of the component (a) is (a1) a linear polyorganosiloxane, which is represented by the following formula (1): (R a ) 3-p R p Si-O-(Si(R) r (R a ) 2-r O) n -SiR q (R a ) 3-q (1) (In the formula, R a are each independently a curable functional group, Each R is independently a monovalent organic group, p and q are each independently 0, 1 or 2; Each r is independently 0, 1, or 2; n is a number that gives a viscosity of 0.1 to 500 Pa s at 23°C. Examples of the linear polyorganosiloxane are represented by the formula (1). R preferably has a hydrocarbon group, particularly an alkyl group, an alkenyl group, or an aryl group. From the viewpoint of controlling physical properties such as refractive index, at least a part of R may be an aryl group such as a phenyl group. Polyorganosiloxanes in which all R are methyl are particularly preferably used because of their ease of availability. Regarding the position of the curable functional group, polyorganosiloxanes in which r is 2 in the above formula (1), that is, linear polyorganosiloxanes in which at least one curable functional group exists only at both ends of the molecule, are preferred.

[0019] Another specific example of component (a) is (a2) a branched alkenyl-containing polyorganosiloxane. (a2) contains SiO as an essential unit. 4 / 2 Units and RSiO 1 / 2 Including units, RSiO as an arbitrary unit 2 / 2 Units and / or RSiO 3 / 2 In particular, the branched polyorganosiloxanes include those containing the units R 1 or R 2 However, two or more of all R in one molecule are R 1 (i.e., alkenyl group). At least three of all R in one molecule are R 1 and the remainder is R 2 From the viewpoint of providing a cured product of the composition with excellent mechanical strength, it is preferable that the cured product is RSiO 1 / 2 Units and SiO 4 / 2 The molar ratio of the units is in the range of 1:0.8 to 1:3, and the resin is preferably a solid or viscous semi-solid resin at room temperature. In (a2), R 1 is R3SiO 1 / 2 It may also exist as the unit R, RSiO 2 / 2 Units or RSiO 3 / 2 It may also exist as the unit R. From the viewpoint of obtaining fast curing at room temperature, RSiO 1 / 2 Some or all of the units are R 1 R 2 2SiO 1 / 2The unit is R2SiO 2 / 2 Some or all of the units are R 1 R 2 SiO 2 / 2 It is preferable that the unit is a unit.

[0020] The component (a) can be a compound having two or more Si atoms bonded to a group having an aliphatic unsaturated bond, particularly an alkenyl group, such as a (meth)acrylic group or a vinyl group that is cured by addition reaction. The component (a) is preferably a polyorganosiloxane having two or more alkenyl groups in one molecule as a curable functional group. The curable functional group that undergoes the addition reaction is more preferably a vinyl group.

[0021] As the polyorganosiloxane having a curable functional group that undergoes an addition reaction, in the above formula (1), p and q are 2, and r is 2, that is, one each at the molecular end only, a total of two groups capable of addition reaction, particularly vinyl groups, are preferred. Such polyorganosiloxanes that can be used as component (a) can be commercially available. Polyorganosiloxanes into which a curable functional group has been introduced by a known reaction may also be used. As component (a), only one type of compound may be used, or two or more types of compounds may be mixed and used, classified according to the position or type of the substituent, the degree of polymerization, etc. Since component (a) is a polyorganosiloxane, it may be a mixture of polyorganosiloxanes having various degrees of polymerization.

[0022] The amount of component (a) is not particularly limited as long as the curable polyorganosiloxane composition has a viscosity within a range that allows it to be handled. Based on the amount of component (a), the amounts of the other components can be appropriately set within the preferred ranges shown below.

[0023] ·Ingredient (b) The curable polyorganosiloxane composition of the present invention contains, as a crosslinking agent, a compound having three or more crosslinking groups in one molecule that are reactive with the curable functional group of the component (a) (hereinafter, sometimes simply referred to as "component (b)"). By containing a crosslinking agent, the physical properties of the cured product obtained from the curable composition, such as tensile strength and elastic modulus, become good. As the crosslinking group of component (b), a functional group that is generally active in the reaction used in the curing reaction of silicone can be used. As the crosslinking group, for example, a hydrogen atom directly bonded to silicon, that is, a Si-H group, can be adopted. The number of crosslinking groups that component (b) has per molecule is three or more, and therefore a network structure can be obtained by the crosslinking reaction. Each crosslinking group may be bonded to the same silicon atom or different silicon atoms.

[0024] Component (b) may be a compound having only one silicon atom, i.e., a derivative of silane, or may be a compound having two or more silicon atoms. In the case of a compound having two or more silicon atoms, component (b) preferably has a structure in which each silicon atom is linked by a siloxane bond crosslinked by oxygen. The molecular skeleton of component (b) containing two or more silicon atoms may be linear, branched, or cyclic. Only one type of component (b) may be used, or two or more types may be used simultaneously.

[0025] The crosslinking group of component (b) can be an Si-H bond. As a crosslinking agent having such a crosslinking group, hydrogen polyorganosiloxane, which is a siloxane containing a hydrogen group, is used. Hydrogen polyorganosiloxane is a siloxane compound having an Si-H bond, and is a component that serves as a crosslinking agent. Hydrogen polyorganosiloxane is typically represented by the following formula (2): (R b ) x (R c ) y SiO (4-x-y) / 2 (2) (In the formula, R b is a hydrogen atom, R c is C1-6 an alkyl group (e.g., methyl, ethyl, propyl, butyl, pentyl, hexyl, preferably methyl) or a phenyl group; x is 1 or 2; y is an integer from 0 to 2, with the proviso that x+y is an integer from 1 to 3. Preferably, the compound has two or more units represented by the following formula (1) in the molecule so that the number of Si-H bonds is three or more.

[0026] The siloxane skeleton in the hydrogen polyorganosiloxane may be cyclic, branched, or linear, but is preferably cyclic or linear, and more preferably linear. The main chain of the hydrogen polyorganosiloxane is preferably a linear skeleton, but may be a skeleton having a branched structure as a substituent. The number of hydrogen groups (i.e., equivalent to Si-H bonds) bonded to silicon atoms contained in one molecule is 3 or more, more preferably 5 or more on average per molecule, and even more preferably 8 or more. Other conditions in the hydrogen polyorganosiloxane, such as organic groups other than hydrogen groups, bonding positions, degree of polymerization, structure, etc., are not particularly limited, but in the case of a linear structure, a degree of polymerization in the range of 5 to 200, particularly 10 to 100, is preferred because the handleability of the resulting composition tends to be improved. Specific examples of hydrogen polyorganosiloxanes that can be used include units (M H Or D H The hydrogen polyorganosiloxane has a linear skeleton and contains 8 or more aryl groups (units) and has a degree of polymerization in the range of 10 to 100.

[0027] Component (b) may contain, for example, 0.1 to 20 moles of crosslinking groups per mole of reactive functional group of component (a), specifically, 0.2 to 10 moles. The amount of component (b) may be designed to be within an appropriate range according to the amount of reactive functional group of component (a) using the criteria described below. Component (b) may be classified according to the position or type of crosslinking group, or the degree of polymerization in the case of hydrogen polyorganosiloxane, and may be used as a single compound or a mixture of two or more compounds. Component (b) may be a mixture of hydrogen polyorganosiloxanes having various degrees of polymerization. The siloxane skeleton in component (b) may be linear, branched or cyclic, with linear being preferred.

[0028] The component (b) is (b1), each of both ends of which is independently R 5 3SiO 1 / 2 It is blocked by units, and the intermediate unit is R 5 2SiO 2 / 2 A linear hydrogen polyorganosiloxane consisting of only units, or (b2) R 5 3SiO 1 / 2 Units and SiO 4 / 2 Hydrogen polyorganosiloxane (R 5 are each independently a hydrogen atom or a monovalent hydrocarbon group having no aliphatic unsaturated bonds, provided that R 5 In the cases of (b1) and (b2), at least three of R 5 3SiO 1 / 2 The unit is HR. 6 2SiO 1 / 2 Units and R 6 3SiO 1 / 2 The units are listed as R 5 2SiO 2 / 2 The unit is HR. 6 SiO 2 / 2 Units and R 6 2SiO 2 / 2 Units (in the above formulas, R 6is a monovalent hydrocarbon group having no aliphatic unsaturated bonds. In the case of (b1), the hydrogen atom bonded to the silicon atom may be present at the terminal or in the middle unit, but is preferably present in the middle unit.

[0029] As component (b), (b1-1) is a copolymer in which both ends are blocked with M units (trimethylsiloxane units) and the middle unit is D H (b1-2) a linear polymethylhydrogensiloxane consisting only of units (methylhydrogensiloxane units), (b1-3) a linear polymethylhydrogensiloxane consisting only of units (methylhydrogensiloxane units), (b1-4) a linear polymethylhydrogensiloxane consisting only of units (methylhydrogensiloxane units), (b1-5) a linear polymethylhydrogensiloxane consisting only of units (methylhydrogensiloxane units), (b1-6) a linear polymethylhydrogensiloxane consisting only of units (methylhydrogensiloxane units), (b1-7) a linear polymethylhydrogensiloxane consisting only of units (methylhydrogensiloxane units), (b1-8) a linear polymethylhydrogensiloxane consisting only of units (methylhydrogensiloxane units), H linear polymethylhydrogensiloxane consisting only of units (methylhydrogensiloxane units) and having 0.1 to 3.0 moles of methylhydrogensiloxane units per mole of dimethylsiloxane units, or (b2-1) M H unit (dimethylhydrogensiloxane unit) and Q unit (SiO 4 / 2 Polymethylhydrogensiloxane consisting only of the unit) is particularly preferred.

[0030] Component (b) may be one type or a combination of two or more types.

[0031] When component (b) is a hydrogen polyorganosiloxane, the amount of the component (b) is preferably such that the number of hydrogen atoms directly bonded to silicon atoms is 0.1 to 10.0 per one unsaturated group such as a curable functional group, particularly a vinyl group, of component (a). If the number is less than 0.1, the curing may not proceed at a sufficient speed, and if the number is more than 10.0, the cured product may become too hard and may have a negative effect on the physical properties after curing. When the curable functional group is a vinyl group, the amount of polyorganosiloxane having one vinyl group in the molecule can also be adjusted by the ratio (H / Vi ratio) of the amount of substance of the Si-H bond and the unsaturated bond, particularly the vinyl group, of the hydrogen polyorganosiloxane. The H / Vi ratio is preferably in the range of 0.2 to 5.0, more preferably in the range of 0.5 to 3.0. By making the H / Vi ratio 0.2 or more, it is possible to achieve curing at a sufficient speed and to exhibit better adhesion to various substrates. Furthermore, by setting the H / Vi ratio to 5.0 or less, the composition can be cured to a sufficient extent, hardness can be maintained at an appropriate level, heat resistance can be maintained, and better adhesive properties can be maintained.

[0032] In the curable composition, component (b) may contain, for example, 0.1 moles or more of crosslinking groups relative to 1 mole of reactive functional groups of component (a), specifically 0.2 moles or more. Component (b) may contain, for example, 20 moles or less of crosslinking groups relative to 1 mole of reactive functional groups of component (a), specifically 10 moles or less, more specifically 5 moles or less.

[0033] ·Ingredients (c) The curable polyorganosiloxane composition of the present invention contains a curing catalyst capable of catalyzing the crosslinking reaction between the component (a) and the component (b) (hereinafter, sometimes simply referred to as "component (c)"). An addition curing catalyst is used as the curing catalyst. A representative example is a platinum catalyst. The platinum catalyst is a curing catalyst for reacting the curable functional group of the component (b) with the hydrogen group of the component (b) to obtain a cured product. Examples of this platinum compound include chloroplatinic acid, platinum olefin complex, platinum vinylsiloxane complex, platinum phosphorus complex, platinum alcohol complex, platinum black, etc. The amount of the platinum compound is 0.1 to 1000 ppm in terms of platinum element relative to the component (a). If it is less than 0.1 ppm, the composition will not cure sufficiently, and if it exceeds 1000 ppm, no particular improvement in the curing rate can be expected. In addition, in order to obtain a longer pot life depending on the application, the activity of the catalyst can be suppressed by adding a reaction inhibitor. Known reaction inhibitors for platinum group metals include acetylene alcohols such as 2-methyl-3-butyn-2-ol, 3,5-dimethyl-1-hexyn-3-ol, and 1-ethynyl-2-cyclohexanol, diallyl maleate, and tertiary amines such as tetramethylethylenediamine and pyridine.

[0034] ·Ingredient (d) The curable composition of the present invention includes a silicon compound having a monovalent alkyl group having 8 to 30 carbon atoms directly bonded to a silicon atom and a hydrolyzable group (hereinafter, sometimes simply referred to as "component (d)"). Without being bound by a particular theory, it is believed that component (d) migrates to the substrate surface during or after the composition is cured, and causes a reaction in which the hydrolyzable group adheres to the substrate surface, or that component (d) hydrophobicizes the silicone rubber itself, thereby making it difficult for moisture to pass through. In addition, component (d) has an alkyl group with a relatively long carbon chain, which can provide the curable composition with an appropriate hydrophobicity, which is believed to contribute to the water resistance of the entire curable composition. Only one type of component (d) may be used, or two or more types may be used in combination.

[0035] The monovalent alkyl group of component (d) has a carbon number of 8 to 30, and here, it means that the carbon chain to which the carbon atom bonded to the silicon atom belongs has a length of 8 or more carbon atoms. From the viewpoint of affinity with other components in the curable composition, the carbon number is more preferably in the range of 8 to 20. Examples of the monovalent alkyl group include linear alkyl groups such as octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group, and triacontyl group; and branched alkyl groups such as isononyl group and 2-methylnonyl group. The monovalent alkyl group may have one or more functional groups such as bromine, chlorine, and fluorine, as long as they do not reduce hydrophobicity, such as hydroxyl groups.

[0036] As used herein, the term "hydrolyzable group" refers to a group that can undergo hydrolysis, i.e., a group that can be detached from the main skeleton of a compound by hydrolysis. Examples of hydrolyzable groups include -OR', -OCOR', -ON=CR'2, -NR'2, -NHR', and halogen atoms (wherein R' represents a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms), and -OR' (i.e., an alkoxy group) is preferred because it is less likely to cause corrosion to various substrates and is chemically stable as a silicone composition. Examples of R' include unsubstituted alkyl groups such as methyl, ethyl, propyl, isopropyl, n-butyl, and isobutyl groups; and substituted alkyl groups such as chloromethyl groups. Among them, alkyl groups, particularly unsubstituted alkyl groups, are preferred, and methyl or ethyl groups are more preferred. That is, in one embodiment, the hydrolyzable group is preferably an alkoxy group such as a methoxy group, an ethoxy group, a propoxy group, or a butoxy group. The hydroxyl group is not particularly limited, and may be one that is generated by hydrolysis of a hydrolyzable group. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and among these, a chlorine atom is preferred.

[0037] The silicon compound of component (d) is not particularly limited in structure as long as it has at least one monovalent alkyl group having 8 to 30 carbon atoms and at least one hydrolyzable group. The alkyl group may have two or more alkyl groups, and the alkyl groups may be different from each other, but it is preferable that component (d) has one monovalent alkyl group. The hydrolyzable group may have two or more hydrolyzable groups in one molecule, but it is preferable that component (d) has three hydrolyzable groups. Component (d) may have a group other than the monovalent alkyl group having 8 to 30 carbon atoms and the hydrolyzable group, such as a lower alkyl group or a phenyl group. The number of silicon atoms that component (d) has in one molecule is not particularly limited, but it is preferable that it is a compound having 1 to 10 silicon atoms, and more preferable that it is a compound having one silicon atom. The monovalent alkyl group and the hydrolyzable group may be bonded to the same silicon atom or different silicon atoms. It is preferable that the monovalent alkyl group and the hydrolyzable group are bonded to the same silicon atom.

[0038] (d) The silicon compound having a monovalent alkyl group having 8 to 30 carbon atoms and a hydrolyzable group directly bonded to a silicon atom is preferably represented by the following formula (3): R 1 n Si(OR 2 ) 4-n (3) (In the formula, R 1 is a monovalent alkyl group having 8 to 30 carbon atoms, preferably a monovalent alkyl group having 8 to 20 carbon atoms, R 2 is hydrogen or an alkyl group having 1 to 6 carbon atoms, and n is an integer of 1 to 3, preferably 1. In a particularly preferred embodiment, component (d) is a compound having one monovalent alkyl group and three hydrolyzable groups on one silicon atom.

[0039] As component (d), a commercially available silicon compound that satisfies the above conditions may be used, or a compound prepared by a method known to those skilled in the art may be used.Specific examples of the compound include octyltrimethoxysilane, decyltrimethoxysilane, hexadecyltrimethoxysilane, octadecyltrimethoxysilane, and octyltriethoxysilane.

[0040] The component (d) is preferably contained in an amount of 0.01 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, and even more preferably 0.3 to 2.5 parts by mass, relative to 100 parts by mass of the curable polyorganosiloxane composition of the present invention. By setting the amount within this range, it is possible to impart sufficient hydrophobicity to the composition to exhibit water resistance, and the properties of the adhesive when used as an adhesive are not impaired.

[0041] ·Ingredient (e) The curable polyorganosiloxane composition of the present invention may contain a scaly inorganic filler as an optional additional component (hereinafter, may be simply referred to as "component (e)"). It is believed that the scaly inorganic filler can play a role in spatially preventing the intrusion of moisture into the adhesive layer when the curable polyorganosiloxane composition of the present invention is used as an adhesive. Therefore, component (e) can contribute to the water resistance of the curable polyorganosiloxane composition. There are no particular limitations on the type of inorganic fine particles as long as they are scaly, but silicon oxides and silicate minerals are preferred. 、 Mica fine powder is more preferable. These scaly inorganic fine particles may be used alone or in combination of two or more kinds.

[0042] The average particle size of the scaly inorganic filler is preferably 100 μm or less, more preferably 50 μm or less, and particularly preferably 30 μm or less, from the viewpoint of maintaining dispersibility and fluidity of the curable composition. Here, the average particle size of the scaly inorganic filler means the length of the scaly particles in the major axis direction. The measured value of the average particle size is the median size (d50) measured by a laser diffraction / scattering method.

[0043] Component (e) is preferably contained in an amount of 10 to 500 parts by mass, more preferably 15 to 300 parts by mass, and even more preferably 20 to 200 parts by mass, per 100 parts by mass of the total of components (a) to (d). If the amount added is less than 10 parts by mass per 100 parts by mass of the total of components (a) to (d), the effect on water resistance is insufficient, whereas if it is more than 500 parts by mass, the viscosity increases and handling may be impaired.

[0044] [Curable polyorganosiloxane composition] The curable polyorganosiloxane of the present invention contains the above components (a) to (d) and optionally further contains the above component (e).

[0045] The polyorganosiloxane composition of the present invention is not particularly limited in its properties as long as each component is uniformly mixed and has a degree of fluidity that allows application to a substrate. The viscosity of the polyorganosiloxane composition can be controlled mainly by the viscosity of component (a), and is preferably in the range of 0.1 to 500 Pa·s from the viewpoint of operability. In addition, the polyorganosiloxane composition can be a one-liquid type composition in which all components are mixed, or a two-liquid type composition in which components (b) and (c) are separately blended. The one-liquid type or two-liquid type composition can be appropriately selected in consideration of workability, curing conditions, etc., and the method is known to those skilled in the art.

[0046] The curable polyorganosiloxane composition of the present invention can be blended with other known components as long as they do not impair the purpose and effect of the composition. As additives, flame retardants, adhesion imparting agents, heat resistance imparting agents, diluents, organic solvents, inorganic or organic pigments, etc. can be appropriately blended. In addition, siloxane resins that do not fall under the above-mentioned component (a) or component (b) can also be blended. Examples of such resins include polyorganosiloxanes having only one curable functional group, polyorganosiloxanes having no curable functional group such as dimethylsiloxane, etc. These resins can be used as diluents.

[0047] <Other resins> The curable polyorganosiloxane composition may further contain a siloxane resin that does not fall under the above-mentioned components (a) and (b). Such a resin can also be used as a diluent for adjusting viscosity. Such a siloxane resin is a resin obtained by combining the above-mentioned M, D, T, and Q units that has no curable functional group or has only one curable functional group, particularly the following formula (4): (R a ) 3-p R p Si-O-(SiRO) n -SiR3···(4) (In the formula, R a , R, p, and n are as defined in formula (1). and siloxanes having only one curable functional group, such as those represented by the formula (5): R3Si-O-(SiRO) n -SiR3···(5) (In the formula, R and n are as defined in formula (1)). It is possible to use a siloxane having no curable functional group, which is represented by the following formula: By using such a siloxane resin, it is possible to control the hardness when the curable polyorganosiloxane composition is cured, and to control the viscosity of the composition, and it is possible to widely respond to the handling properties and required physical properties.

[0048] Such a resin can be contained in the curable polyorganosiloxane composition in an amount of, for example, 50 parts by mass or less, specifically, 0.1 to 50 parts by mass, and more specifically, 1 to 30 parts by mass, per 100 parts by mass of component (a).

[0049] <<Hydrogen polyorganosiloxane with two hydrogen atoms bonded to silicon atoms in the molecule>> The composition may further contain a hydrogen polyorganosiloxane having two hydrogen atoms bonded to silicon atoms in the molecule. Such siloxanes can function as chain extenders by addition reaction with component (a). Examples of such siloxanes are as described in component (b) except that they have two hydrogen atoms bonded to silicon atoms in the molecule. Such siloxanes preferably have two units of the general formula (2) described above in component (b) in the molecule so that the number of Si-H bonds is two.

[0050] The siloxane skeleton in this component may be linear, branched, or cyclic, with linear being preferred. Furthermore, the siloxane in this component has two terminals that are each independently represented by the formula: R 5 3SiO 1 / 2 It is blocked by units, and the intermediate unit is R 5 2SiO 2 / 2 R 5 are each independently a hydrogen atom or a monovalent hydrocarbon group having no aliphatic unsaturated bonds, provided that R 5 Among these, two are hydrogen atoms per molecule), and linear hydrogen polyorganosiloxane is more preferred. The hydrogen atoms bonded to the silicon atoms may be present at the terminals or in the intermediate units, but are preferably present at the terminals. Therefore, the siloxane of this component is preferably one in which both terminals are M H Particularly preferred is polymethylhydrogensiloxane that is blocked with D units (dimethylhydrogensiloxane units) and has intermediate units consisting only of D units (dimethylsiloxane units).

[0051] <Adhesion promoter> The curable polyorganosiloxane composition may further include an adhesion promoter. The adhesion promoter is a component that improves the adhesion of the cured product of the composition to substrates such as glass, metal, and plastic. Examples of adhesion promoters include metal alkoxides, compounds having a hydrolyzable silyl group, compounds having a hydrolyzable silyl group and a reactive organic functional group in one molecule, compounds having a hydrogen atom bonded to a silicon atom and a divalent aromatic group in one molecule, compounds having a hydrogen atom bonded to a silicon atom and a reactive organic functional group in one molecule, and / or partial hydrolysis condensates thereof. Examples of metal alkoxides include aluminum alkoxides such as aluminum triethoxide, aluminum tripropoxide, and aluminum tributoxide; titanium alkoxides such as titanium tetraethoxide, titanium tetrapropoxide, titanium tetraisopropoxide, titanium tetrabutoxide, titanium tetraisobutoxide, and titanium tetraisopropenyl oxide. Examples of organic compound adhesion promoters include amino group-containing silanes, isocyanurates, and carbasilatran compounds.Specific examples include tetraethoxysilane, tetramethoxysilane oligomers, vinyltrimethoxysilane, vinyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3,4-epoxycyclohexylethyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-acryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, and 3-methacryloxypropylmethyldiethoxysilane.

[0052] Further examples of the adhesion promoter include the following. (E1) A hydrogen atom bonded to a silicon atom and a group represented by the following formula (6): [ka] and an organosilicon compound having a side chain represented by (E2)Si(OR 3 ) n an organosilicon compound having a group and an epoxy group-containing group, and / or a partial hydrolysis condensate thereof; (E3)Si(OR 3 ) n A silane compound having a group and an aliphatic unsaturated hydrocarbon group, and / or a partial hydrolysis condensate thereof, (E4)Si(OR 4 ) A tetraalkoxysilane compound represented by the formula (4) and / or a partial hydrolysis condensation product thereof. (In each of the above formulas, Q 1 represents a linear or branched alkylene group that forms a carbon chain having two or more carbon atoms between the silicon atom and the ester bond; Q 2 represents a linear or branched alkylene group that forms a carbon chain having three or more carbon atoms between the oxygen atom and the silicon atom of the side chain; R 3 represents an alkyl group having 1 to 4 carbon atoms or a 2-methoxyethyl group; R 4 represents an alkyl group having 1 to 3 carbon atoms; and n is an integer of 1 to 3.

[0053] Each of (E1), (E2), (E3) and (E4) may be one type or a combination of two or more types. For example, (E) may be a combination of one type of (E1), two types of (E2) and two types of (E3).

[0054] <<(E1)>> (E1) is a component that undergoes an addition reaction with (A) during curing of the composition, and is introduced into the siloxane structure crosslinked by the addition reaction with (A) and (B), and the side chain of formula (6) is a component that contributes to the adhesiveness of the composition at room temperature as a part that exhibits adhesiveness. In addition, the alkoxy group (hereinafter, OR) present in the side chain of (E1) 3 represents an alkoxy group having 1 to 4 carbon atoms or a 2-methoxyethoxy group) contributes to the introduction of (E2), (E3) and / or (E4) into the siloxane structure by cohydrolysis and condensation reaction with the alkoxy group of (E2), (E3) and / or (E4).

[0055] Q 1 Ethylene and 2-methylethylene groups are preferred because of their ease of synthesis and handling. 2 R is preferably a trimethylene group because of ease of synthesis and handling. 3 Methyl and ethyl groups are preferred, with a methyl group being particularly preferred, since these provide good adhesion and the alcohol produced by hydrolysis is easily volatilized.

[0056] The hydrogen atom and the side chain, which are the characteristics of (E1), are preferably bonded to separate silicon atoms for ease of synthesis. Therefore, the basic portion of (E1) preferably forms a linear, branched or cyclic siloxane skeleton, and a cyclic siloxane skeleton is particularly preferred because it allows for well-controlled synthesis and purification of specific compounds. The number of Si-H bonds contained in (E1) is any number of 1 or more, and in the case of a cyclic siloxane compound, 2 or 3 is preferred.

[0057] Examples of (E1) include the following compounds: [ka]

[0058] <<(E2)>> (E2) is a component that is introduced into the crosslinked siloxane structure by cohydrolysis and condensation reaction of an alkoxy group bonded to a silicon atom with an alkoxy group bonded to a silicon atom in (E1), (E3) and / or (E4). As the epoxy group exerts adhesive properties, (E2) is a component that contributes to improving the adhesiveness of the composition at room temperature, particularly the adhesiveness to plastics.

[0059] R 3is preferably a methyl group or an ethyl group, with a methyl group being particularly preferred, since it provides good adhesion. n is preferably 2 or 3. As the epoxy group-containing group, an aliphatic epoxy group-containing group containing an ether oxygen atom, such as a 3-glycidoxypropyl group, and an alicyclic epoxy group-containing group, such as a 2-(3,4-epoxycyclohexyl)ethyl group, are preferred, since they are easy to synthesize, are not hydrolyzable, and exhibit excellent adhesion. Si(OR 3 ) n There may be two or more OR groups in a molecule. 3 The number of OR groups in the molecule is preferably 2 or more. 3 The group and the epoxy group-containing group may be bonded to the same silicon atom or to different silicon atoms.

[0060] Examples of (E2) include 3-glycidoxypropyl group-containing alkoxysilanes such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, and 3-glycidoxypropyl(methyl)dimethoxysilane; 2-(3,4-epoxycyclohexyl)ethyl group-containing alkoxysilanes such as 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyl(methyl)dimethoxysilane; partial hydrolysis condensates of these silanes where n is 2 or more; and carbon / silicon bifunctional siloxanes in which a portion of the methyl groups of linear or cyclic methylsiloxanes is replaced with trimethoxysiloxy groups or 2-(trimethoxysilyl)ethyl groups and the above-mentioned epoxy group-containing groups.

[0061] <<(E3)>> (E3) undergoes an addition reaction with (B) during curing of the composition, and is introduced into the siloxane structure crosslinked by the addition reaction with (A) and (B). The alkoxy groups present in the side chains are the moieties that exhibit adhesive properties, and contribute to improving the adhesiveness of the composition at room temperature, particularly the adhesiveness to metals. The alkoxy groups of (E3) also contribute to being introduced into the siloxane structure crosslinked with (E1), (E2) and / or (E4) by cohydrolysis and condensation reactions with the alkoxy groups of (E1), (E2) and / or (E4). (E3) is a compound represented by the formula Si(OR 3 ) n It is preferable that the silane compound is a silane compound having a group and one aliphatic unsaturated hydrocarbon group, and / or a partial hydrolysis condensate thereof. When the alkoxy group is used in combination with another alkoxy group of (E3) and (E2), the other (E3) and / or (E2) is introduced into the siloxane structure by a co-hydrolysis / condensation reaction with the alkoxy group of (E2).

[0062] R 3 is preferably a methyl group or an ethyl group, with a methyl group being particularly preferred, since it provides good adhesion. n is preferably 2 or 3. The aliphatic unsaturated hydrocarbon group is preferably a monovalent group. In the case of an alkenyl group such as vinyl, allyl or 3-butenyl, the aliphatic unsaturated hydrocarbon group may be directly bonded to a silicon atom, or an unsaturated acyloxy group may be bonded to a silicon atom via three or more carbon atoms, such as 3-acryloxypropyl or 3-methacryloxypropyl. As the unsaturated hydrocarbon group-containing group, a vinyl group, a methacryloxypropyl group, etc. are preferred, since they are easy to synthesize and handle. Si(OR 3 ) n There may be two or more OR groups in a molecule. 3 The number of OR groups in the molecule is preferably 2 or more. 3 The group and the aliphatic unsaturated hydrocarbon group may be bonded to the same silicon atom or to different silicon atoms.

[0063] Examples of (E3) include alkenylalkoxysilanes such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, methylvinyldimethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, and methylallyldimethoxysilane, and / or partial hydrolysis condensates thereof; (meth)acryloxypropyl(methyl)di- and (meth)acryloxypropyltri-alkoxysilanes such as 3-acryloxypropyltrimethoxysilane, 3-acryloxypropyltriethoxysilane, 3-acryloxypropyl(methyl)dimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, and 3-methacryloxypropyl(methyl)dimethoxysilane, and / or partial hydrolysis condensates thereof.

[0064] <<(E4)>> (E4) is a component that further improves the adhesion of the composition to metals at room temperature. 4 Examples of the alkyl group include linear or branched alkyl groups such as methyl, ethyl, propyl, and isopropyl, and the methyl and ethyl groups are preferred because they are easily available, easy to handle, and have a significant effect of improving adhesion. In addition, although (E4) can be used as a tetraalkoxysilane compound alone, it is preferred that it is a partial hydrolysis condensate of a tetraalkoxysilane compound because of its excellent hydrolysis property and low toxicity.

[0065] <<Other adhesion promoters>> Examples of adhesion promoters other than (E1) to (E4) include metal alkoxides such as aluminum triethoxide, aluminum tripropoxide, and aluminum tributoxide; titanium alkoxides such as titanium tetraethoxide, titanium tetrapropoxide, titanium tetraisopropoxide, titanium tetrabutoxide, titanium tetraisobutoxide, and titanium tetraisopropenyl oxide; zirconium acylates such as zirconium octanoate, zirconium tetra(2-ethylhexanoate), and zirconium stearate; zirconium alkoxides (excluding zirconium chelates) such as n-propyl zirconate and n-butyl zirconate; and zirconium chelates such as tributoxyzirconium acetylacetonate, dibutoxyzirconium bis(ethylacetoacetate), zirconium tetraacetylacetonate, zirconium monoacetylacetonate, and zirconium ethylacetoacetate.

[0066] Other adhesion promoters include, [ka] [ka] Compounds having a hydrolyzable silyl group and a reactive organic functional group in one molecule and / or partial hydrolysis condensates thereof (however, not including (E1) to (E4)); [ka] Compounds having a hydrogen atom bonded to a silicon atom and a reactive organic functional group in one molecule, such as those mentioned above; [ka] (wherein k is an integer of 1 to 3) and other compounds having a hydrogen atom bonded to a silicon atom and a divalent aromatic group in one molecule. The adhesive strength can be further increased by using other adhesion promoters in combination.

[0067] (E) preferably includes a combination of (E1), (E2), (E3) and / or (E4). Each of (E1) to (E4) may be a combination of one or more of them. For example, (E) may be a combination of one type of (E1), two types of (E2) and two types of (E3).

[0068] The adhesion promoter may be contained in the curable polyorganosiloxane composition in an amount of, for example, 10 parts by mass or less, specifically, 0.01 to 10 parts by mass, and more specifically, 0.1 to 5 parts by mass, per 100 parts by mass of component (a). One type of adhesion promoter may be used alone, or two or more types may be used in combination.

[0069] <Other inorganic particles> The curable polyorganosiloxane composition of the present invention may contain inorganic fine particles other than the above-mentioned (e). As such inorganic fine particles, inorganic materials used as fillers in silicone rubbers can be used. The particles of the inorganic material may have a shape other than a scaly shape, for example, a spherical shape, an amorphous shape, etc. Examples of inorganic materials include oxides such as fumed silica, calcined silica, silica aerogel, precipitated silica, diatomaceous earth, crushed silica, fused silica, fumed titanium oxide, iron oxide, zinc oxide, titanium oxide, and aluminum oxide; those whose surfaces have been treated with hydrophobizing agents such as trimethylchlorosilane, dimethyldichlorosilane, hexamethyldisilazane, and octamethylcyclotetrasiloxane; carbonates such as calcium carbonate, magnesium carbonate, and zinc carbonate; silicates such as aluminosilicate and calcium silicate; talc; composite oxides such as glass wool; and conductive fillers such as carbon black, copper powder, and nickel powder.

[0070] As another inorganic fine particle, for example, fumed silica is preferably contained in an amount of 1 to 50 parts by mass, more preferably 2 to 30 parts by mass, and even more preferably 5 to 15 parts by mass, relative to 100 parts by mass of the entire curable composition of the present invention. Within this range, it is possible to adjust the flowability of the composition before curing and reinforce the hardness, durability, etc., of the composition when cured, without impairing the effects of the present invention. As for inorganic fillers other than fumed silica, those skilled in the art can appropriately change the blending amount depending on the type and role of the filler.

[0071] <Solvent> The curable polyorganosiloxane composition may contain a solvent. In this case, the curable polyorganosiloxane composition may be dissolved in a suitable solvent at a desired concentration depending on its application and purpose. The concentration of the solvent may be, for example, 80 parts by mass or less, 50 parts by mass or less, 30 parts by mass or less, or 20 parts by mass or less, relative to 100 parts by mass of the curable polyorganosiloxane composition. From the viewpoint of adjusting the viscosity of the curable composition, it is preferable to contain a solvent. By containing a solvent, the handleability of the curable composition may be improved.

[0072] One aspect of the present invention is an adhesive comprising the curable polyorganosiloxane composition. The adhesive preferably comprises the adhesion promoter in addition to the curable polyorganosiloxane composition.

[0073] In the article using the curable polyorganosiloxane composition of the present invention as an adhesive, the cured product of the composition and various substrates only need to have an adhesive part, and the shape is not limited.For example, one embodiment of the method for producing an article that includes an adhesive part between a substrate and a cured product of the composition includes the steps of preparing a part and a composition that includes a substrate; applying the composition to the surface of the substrate; and curing the composition to adhere the substrate and the cured product of the composition.

[0074] The adhesive containing the curable polyorganosiloxane composition of the present invention is applied to a substrate, and the material is not particularly limited. As the substrate, metals such as aluminum, copper, nickel, iron, brass, and stainless steel; engineering plastics such as epoxy resin, polyester resin such as polyethylene terephthalate and polybutylene terephthalate (PBT) resin, polycarbonate resin, acrylic resin, polyimide resin, phenolic resin, polyamide resin, polyphenylene sulfide (PPS) resin, and modified polyphenylene ether (PPE) resin; and glass can be used. In addition, if necessary, the wall surface of the gap may be subjected to a primer treatment according to a conventional method. The shape and thickness of the substrate are not particularly limited.

[0075] The adhesive containing the curable polyorganosiloxane composition is applied to the surface of the part including the substrate at a predetermined thickness by a method such as dripping, pouring, casting, extrusion from a container, coating such as bar coating and roll coating, screen printing, dipping, brushing, spraying, and dispensing. These methods are known to those skilled in the art. The composition may be applied entirely and uniformly on the surface of the part, or may be applied unevenly or partially, such as in lines, stripes, dots, etc. The application thickness of the composition is usually 0.01 to 3 mm, preferably 0.05 to 2 mm.

[0076] The composition applied to the surface of the part can be cured by leaving it at room temperature (e.g., 23°C) or by heating it to a higher temperature, thereby bonding the substrate and the cured product of the composition. When heated to a higher temperature, curing can be completed in a shorter time than at room temperature, which can improve work efficiency.

[0077] The heating conditions can be appropriately adjusted according to the heat resistance temperature of the member to which the composition is applied, and the curing time can be determined. For example, heat above room temperature (23°C) and up to 200°C can be applied for 1 minute to 2 weeks, preferably 5 minutes to 72 hours. From the viewpoint of operability, the heating temperature is preferably 40 to 180°C, and particularly preferably 50 to 150°C. From the viewpoint of simplicity of the curing process, the heating time is preferably 5 minutes to 72 hours, and particularly preferably 5 minutes to 24 hours. In addition, when curing at room temperature, the curing time is preferably 1 week or less, more preferably 72 hours or less, and particularly preferably 24 hours or less.

[0078] Articles using the curable polyorganosiloxane composition of the present invention as an adhesive have excellent durability, including water resistance of the adhesive surface, and can be used favorably as various parts in aircraft, automobile applications, and the electronic materials field. EXAMPLES

[0079] The composition of the present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the embodiments of these examples. In the following examples, Examples 7 to 10 in which quartz powder is used shall be read as "Reference Examples".

[0080] <Preparation of Curable Polyorganosiloxane Composition> [Example 1] As component (a), a predetermined amount of M5D Vi Q8 (Note: M 5 D Vi Q 8 is a non-linear polyorganosiloxane having a branched structure due to Q units. M dissolved in vi D n1 M vi (wherein n1 is a value such that the viscosity at 23°C is 10 Pa s) vi D n2 M viA linear polymethylvinylsiloxane represented by the formula (where n2 is a value such that the viscosity at 23°C is 1.0 Pa·s), fumed silica and calcium carbonate treated with hexamethyldisilazane (HMDZ) as fillers, and flaky mica (average particle size 23 μm) as component (e) were transferred to a universal kneader and stirred at room temperature (23°C) for 60 minutes, and then stirred under reduced pressure at 150°C for 60 minutes. The mixture was cooled to below 50°C, and a Pt-octanol complex with a platinum content of 3.4% and a reaction inhibitor were added as component (c), and stirred for 30 minutes. MD H 20 D 20 Hydrogen polyorganosiloxane represented by M, octyltriethoxysilane (C8H 17 Si(OEt)3) and an adhesion promoter were added and stirred at room temperature for 10 minutes. As the adhesion promoter, 3-glycidoxypropyltrimethoxysilane, vinyltrimethoxysilane, and a siloxane represented by the following formula were used. [ka] The reaction inhibitors used were diallyl maleate and 3,5-dimethyl-1-hexyn-3-ol.

[0081] [Example 2] Composition 2 was obtained in the same manner as in Example 1, except that the amount of octyltriethoxysilane used in Example 1 was changed from 0.5 parts by mass to 1.5 parts by mass.

[0082] [Example 3] The octyltriethoxysilane used in Example 1 was replaced with decyltrimethoxysilane (C 10 H 21 Composition 3 was obtained in the same manner as in Example 1, except that Si(OMe)3) was changed to 0.5 parts by mass.

[0083] [Example 4] Composition 4 was obtained in the same manner as in Example 3, except that the amount of decyltrimethoxysilane used in Example 3 was changed from 0.5 parts by mass to 1.5 parts by mass.

[0084] [Example 5] The octyltriethoxysilane used in Example 1 was replaced with hexadecyltrimethoxysilane (C 16 H 33 Composition 5 was obtained in the same manner as in Example 1, except that Si(OMe)3) was changed to 0.5 parts by mass.

[0085] [Example 6] Composition 6 was obtained in the same manner as in Example 5, except that the amount of hexadecyltrimethoxysilane used in Example 5 was changed from 0.5 parts by mass to 1.5 parts by mass.

[0086] [Comparative Example 1] The octyltriethoxysilane used in Example 1 was replaced with hexyltrimethoxysilane (CH 11 A composition was obtained in the same manner as in Example 1, except that Si(OMe)3) was changed to 0.5 parts by mass.

[0087] [Comparative Example 2] The octyltriethoxysilane used in Example 2 was replaced with hexyltrimethoxysilane (CH 11 A composition was obtained in the same manner as in Example 2, except that the amount of Si(OMe)3) was changed to 1.5 parts by mass.

[0088] [Comparative Example 3] A composition was obtained in the same manner as in Example 1, except that a silane compound corresponding to component (d) was not used.

[0089] [Comparative Example 4] A composition was obtained in the same manner as in Comparative Example 3, except that quartz powder (average particle size: 5 μm) was used as the inorganic fine particles instead of flaky mica.

[0090] [Test Example 1: Peel test] The composition of the Example or Comparative Example was applied to a 2 mm thick aluminum plate in a uniform thickness (0.5 mm), and the composition was cured by heating at 150°C for 1 hour in a hot air circulation dryer. The aluminum plate coated with the cured product of the polyorganosiloxane composition was immersed in warm water at 80°C, and a peel test was performed after a specific time had passed. The aluminum plate was manually peeled off, and the peeled surface was visually observed. The results are summarized in Tables 1 and 2. In the tables, ◯ indicates that cohesive failure occurred, and at this time the adhesive retains adhesion to the substrate. △ indicates that cohesive failure and peeling were mixed, and × indicates that the adhesive peeled off. The horizontal line (-) indicates that the test was omitted after the adhesive had peeled off.

[0091] [Table 1]

[0092] In Comparative Example 3, which does not contain a silane compound having a long-chain alkyl group, which corresponds to a conventional adhesive, the adhesive site peeled off within two weeks in the test under the above conditions. On the other hand, Examples 1 to 6 show that adding a silane compound having a long-chain alkyl group improves long-term water resistance. Comparative Examples 1 and 2, which contain a hexyltrialkoxysilane having a small carbon chain number, only show water resistance comparable to that of Comparative Example 3, which does not contain a silane compound, and do not provide long-term stability. Comparisons between Examples 1 to 6 and Comparative Examples 1 and 2 show that using a silane compound having a long-chain alkyl group is more effective in improving water resistance than an alkylsilane compound having a small carbon chain number. Comparisons between Comparative Examples 3 and 4 also show that scaly fine particles are effective in improving water resistance.

[0093] [Example 7] Composition 7 was obtained in the same manner as in Example 3, except that the scaly mica was replaced with quartz powder (average particle size 5 μm) and the tetraethoxysilane used as the adhesion promoter was replaced with tetramethoxysilane oligomer.

[0094] [Example 8] Composition 8 was obtained in the same manner as in Example 7, except that the amount of decyltrimethoxysilane used in Example 7 was changed from 0.5 parts by mass to 1.5 parts by mass.

[0095] [Example 9] Composition 9 was obtained in the same manner as in Example 7, except that the decyltrimethoxysilane used in Example 7 was changed to 0.5 parts by mass of hexadecyltrimethoxysilane.

[0096] [Example 10] Composition 10 was obtained in the same manner as in Example 9, except that the amount of hexadecyltrimethoxysilane used in Example 9 was changed from 0.5 parts by mass to 1.5 parts by mass.

[0097] [Comparative Example 5] A composition was obtained in the same manner as in Example 7, except that the decyltrimethoxysilane used in Example 7 was changed to 0.5 parts by mass of hexyltrimethoxysilane.

[0098] [Comparative Example 6] The decyltrimethoxysilane used in Example 8 was replaced with hexyltrimethoxysilane (CH 11 A composition was obtained in the same manner as in Example 8, except that Si(OMe)3) was changed to 1.5 parts by mass.

[0099] [Comparative Example 7] A composition was obtained in the same manner as in Example 7, except that a silane compound corresponding to component (d) was not used.

[0100] [Test Example 2: Peel test] A peel test of the composition was carried out under the same conditions as in Test Example 1. The results are shown in Table 2.

[0101] [Table 2]

[0102] Comparison of Examples 7 to 10 and Comparative Examples 5 to 7 revealed that even in systems having different inorganic fine particles, a silane compound having a long-chain alkyl group was highly effective in improving water resistance. [Industrial Applicability]

[0103] The composition of the present invention has high water resistance over a long period of time and is useful for bonding substrates having portions that are expected to come into contact with moisture. Therefore, it can be used as an adhesive for aircraft and automobiles.

Claims

1. (a) a polyorganosiloxane having two or more alkenyl groups capable of undergoing an addition reaction in one molecule; (b) a crosslinking agent having three or more crosslinking groups reactive with the alkenyl group of (a) in one molecule; (c) a curing catalyst capable of catalyzing the crosslinking reaction of (a) and (b); (d) The following formula: R １ ｎ Si(OR ２ ) ４－ｎ (In the formula, R １ is a monovalent alkyl group having 8 to 30 carbon atoms, R ２ is hydrogen or an alkyl group having 1 to 6 carbon atoms, and n is an integer of 1 to 3), and a silicon compound having a monovalent alkyl group having 8 to 30 carbon atoms and a hydrolyzable group bonded directly to a silicon atom; (e) Inorganic fine particles having a scaly shape and made of silica, silicate minerals or a mixture thereof wherein the (a) is represented by the following formula (1): (R a ) 3-p R p Si-O-(Si(R) r (R a ) 2-r O) n -SiR q (R a ) 3-q ...(1) (In the formula, Each R a is independently an alkenyl group; Each R is independently a monovalent organic group; p and q are each independently 0, 1 or 2; Each r is independently 0, 1, or 2; n is a number that provides a viscosity of 0.1 to 500 Pa s at 23°C. The linear polyorganosiloxane is represented by: The curable polyorganosiloxane composition, wherein the (e) inorganic fine particles having a scale-like shape are contained in an amount of 10 to 38.7 parts by mass per 100 parts by mass of the total of the (a) to (d) components.

2. The curable polyorganosiloxane composition of claim 1 , wherein (c) is a platinum compound.

3. The silicon compound having a monovalent alkyl group having 8 to 30 carbon atoms and a hydrolyzable group directly bonded to a silicon atom (d) has a monovalent alkyl group having 8 to 20 carbon atoms. The curable polyorganosiloxane composition according to claim 1 or 2.

4. The (d) silicon compound having a monovalent alkyl group having 8 to 30 carbon atoms and a hydrolyzable group directly bonded to a silicon atom is contained in an amount of 0.01 to 10.0 parts by mass per 100 parts by mass of the entire composition. The curable polyorganosiloxane composition according to any one of claims 1 to 3.

5. The curable polyorganosiloxane composition according to any one of claims 1 to 4, further comprising an adhesion promoter.

6. An adhesive comprising the curable polyorganosiloxane composition according to any one of claims 1 to 5.

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