Room temperature curable silicone composition

Abstract

The present invention is a moisture-curable silicone composition comprising: (A) a polyorganosiloxane having two or more hydroxyl groups or hydrolyzable groups in one molecule; (B) a siloxane having two or more-OR2 groups bonded to a silicon atom; (C) a condensation catalyst; (D) a silicon-based tackifier which is a compound having, in one molecule, one or more groups selected from the group consisting of aromatic hydrocarbon-containing groups, epoxy group-containing groups, and linear, branched or cyclic aliphatic unsaturated hydrocarbon groups, and also having, in one molecule, at least one heteroatom in addition to the tackifying functional group; and (E) an inorganic filler. As a result, it is possible to provide a moisture-curable silicone composition which can achieve sufficient adhesiveness and compression set at low temperatures and in a short time in various sealants and potting agents for automotive industrial products and the like that require high reliability.

Description

Technical Field

[0001] The present invention relates to a room temperature curing silicone composition that is particularly useful as an adhesive. Background Art

[0002] Curable organopolysiloxane compositions, which exhibit fluidity in their uncured state and form a rubbery elastomer (silicone rubber) upon curing, are known as materials with excellent heat resistance, cold resistance, weather resistance, and electrical insulation properties. Curable organopolysiloxane compositions are used in various industrial fields as adhesives between components such as O-rings, seals, and gaskets, and between substrates. In particular, demand for silicones to bond metals such as aluminum and aluminum die castings to engineering plastics such as PBT and PET is increasing. To meet these demands, silicone resin compositions containing sulfur-based compounds have been proposed to improve adhesion to substrates and compression set (Patent Documents 1 and 2).

[0003] Curable silicone compositions are classified according to their curing mechanism into addition reaction type and condensation reaction type. Addition reaction type compositions are characterized by their ability to cure quickly by heating, exhibiting excellent curability even in areas with insufficient moisture from the air. Condensation reaction type compositions, while requiring a long curing time, exhibit excellent adhesion even when cured at room temperature. Room temperature curing silicone compositions, because they require little energy for curing, are therefore suitable adhesives for the changing environmental awareness in recent years.

[0004] Among condensation reaction-type (room temperature) curable polyorganosiloxane compositions, curable polyorganosiloxane compositions have been proposed that have improved properties such as flowability, anti-sagging properties, extrudability, adhesion, and adhesion durability by incorporating additives such as fillers and light stabilizers (e.g., Patent Documents 3 and 4).

[0005] While attempts have been made to use curable silicone compositions for bonding metal components, moisture-curing silicone compositions use titanium as a curing catalyst, resulting in poor adhesion to metals and engineering plastics. Therefore, adhesion promoters that do not interfere with the titanium catalyst are often used in combination (Patent Document 5).

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 2018-27997

[0009] Patent Document 2: Japanese Patent Application No. 2018-505917

[0010] Patent Document 3: Japanese Patent Application Laid-Open No. 2001-152020

[0011] Patent Document 4: Japanese Patent Application Laid-Open No. 2002-302606

[0012] Patent Document 5: Japanese Patent Application Laid-Open No. 54-090350 Summary of the Invention

[0013] Problems to be solved by the invention

[0014] When sealants and adhesives made from silicone rubber compositions are applied to metals, the durability of the adhesive is measured from the perspective of water resistance using tests such as salt spray tests and immersion tests. Especially in automotive applications, not only are the environments harsh, often accompanied by heating, but the bonded areas are often exposed to wind and rain. Furthermore, automotive applications also involve the risk of contact with oil. Therefore, to improve the reliability of adhesives, water and oil resistance are considered necessary. Ideally, the adhesive should be able to maintain adhesion for extended periods of several years. However, existing products still lack sufficient water and oil resistance.

[0015] Furthermore, it is known that conventionally used adhesion promoters such as aminosilane are coupled with a condensation catalyst, and when the catalyst is a Group IV metal atom including titanium, curing properties are significantly affected, and thus adhesion is reduced.

[0016] An object of the present invention is to provide a moisture-curable silicone composition having high adhesiveness and excellent water resistance, salt water resistance, and oil resistance.

[0017] Means for solving problems

[0018] The present inventors have conducted research and found that a silicone composition that can solve the above-mentioned problems can be obtained by using a hydrolyzable compound having a cyclic structure, particularly an aromatic ring or a heterocyclic ring, and containing a thioether bond as an adhesion promoter, thereby achieving the present invention.

[0019] Effects of the Invention

[0020] According to the present invention, a moisture-curable silicone composition having high adhesiveness and excellent water resistance, salt water resistance, and oil resistance can be provided. Specifically, the present invention relates to the following [1] to [6].

[0021] [1] A moisture-curable silicone composition comprising:

[0022] (A) a polyorganosiloxane having two or more hydroxyl groups or hydrolyzable groups bonded to silicon atoms in one molecule;

[0023] (B) Siloxane compounds having two or more -OR groups bonded to silicon atoms in one molecule 2Base (here, R 2 Each occurrence is independently a hydrogen atom or a monovalent organic group);

[0024] (C) a condensation catalyst;

[0025] (D) a silicone-based tackifier, which is a compound having one or more tackifying functional groups selected from the group consisting of an aromatic hydrocarbon-containing group, an epoxy-containing group, and a linear, branched, or cyclic aliphatic unsaturated hydrocarbon group in one molecule, and having at least one heteroatom in addition to the tackifying functional groups in one molecule (excluding compounds corresponding to (A) or (B) above); and

[0026] (E) inorganic fillers,

[0027] In the moisture-curable silicone composition, the content of the component (D) is 0.05 to 20 parts by mass relative to 100 parts by mass of the component (A).

[0028] [2] The moisture-curable silicone composition according to [1], wherein the component (D) is at least one selected from the group consisting of a sulfur compound, a nitrogen compound, and a phosphorus compound.

[0029] [3] The moisture-curable silicone composition according to [1] or [2], wherein the component (D) is a silicone having at least one SiR 5 3-n (OR 5 ) n Base (here, R 5 An organosilicon compound and / or a partially hydrolyzed condensate thereof (where n is a monovalent hydrocarbon group having no aliphatic unsaturated bond, and n is 1, 2 or 3).

[0030] [4] The moisture-curable silicone composition according to [3], wherein the component (D) further comprises one or more groups selected from the group consisting of an aromatic hydrocarbon-containing group, an epoxy-containing group, and an aliphatic unsaturated hydrocarbon group.

[0031] [5] The moisture-curable silicone composition according to any one of [1] to [4], wherein the component (A) comprises two R-terminated a 3-m R 3 m SiO 1 / 2 The unit is closed and the middle unit is R 3 2SiO 2 / 2 Unit linear polyorganosiloxane (here, R a is a hydroxyl group or a group capable of hydrolysis, R 3is a hydrogen atom or a monovalent hydrocarbon group having no aliphatic unsaturated bond, and m is 0, 1 or 2).

[0032] [6] The moisture-curable silicone composition according to any one of [1] to [5], wherein:

[0033] The component (B) comprises a compound represented by the following formula or a partial hydrolysis-condensation product thereof:

[0034] R 1 n Si (OR 2 ) 4-n

[0035] (Where R 1 Each occurrence is independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 12 carbon atoms, R 2 Each occurrence is independently a hydrogen atom, or an alkyl or alkenyl group having 1 to 12 carbon atoms, which may have a -C(=O)-, -NR'- or -N=C(R')- group at the terminal, or one or more hydrogen atoms may be substituted by a halogen or alkoxy group (wherein R' is an alkyl group having 1 to 6 carbon atoms, which may form a ring together with the carbon portion of the alkyl or alkenyl group), and n is 0, 1 or 2). DETAILED DESCRIPTION

[0036] As described above, the present invention relates to a moisture-curable silicone composition comprising (A) a polyorganosiloxane having two or more hydroxyl groups or hydrolyzable groups bonded to silicon atoms in one molecule; and (B) a siloxane compound having two or more -OR groups bonded to silicon atoms in one molecule. 2 Base (here, R 2 (where each occurrence is independently a hydrogen atom or a monovalent organic group); (C) a condensation catalyst; (D) a silicone-based tackifier, which is a compound having one or more tackifying functional groups selected from an aromatic hydrocarbon-containing group, an epoxy-containing group, and a linear, branched, or cyclic aliphatic unsaturated hydrocarbon group, and having at least one heteroatom in addition to the tackifying functional groups (excluding compounds corresponding to (A) or (B) above); and (E) an inorganic filler. In the moisture-curable silicone composition, the content of component (D) is 0.05 to 20 parts by mass per 100 parts by mass of component (A). The composition of the present invention is described in detail below, item by item. It should be noted that in this specification, the term "to" indicating a numerical range is used to include the numerical values ​​before and after it as the lower and upper limits.

[0037] As used in this specification, the term "organic group" refers to a group containing carbon. The valence of an organic group is indicated by setting n to an arbitrary natural number and writing it as "n-valent." Thus, for example, a "monovalent organic group" refers to a group containing carbon with only one bonding end. Elements other than carbon may also have bonding ends. Even when the valence is not specifically indicated, those skilled in the art will be able to understand the appropriate valence based on the context.

[0038] As used in this specification, the term "hydrocarbon group" refers to a group containing carbon and hydrogen, with at least one hydrogen atom removed from the molecule. This hydrocarbon group is not particularly limited, and examples include hydrocarbon groups having 1 to 20 carbon atoms that may be substituted with one or more substituents, such as aliphatic hydrocarbon groups and aromatic hydrocarbon groups. The aforementioned "aliphatic hydrocarbon group" may be linear, branched, or cyclic, and may be saturated or unsaturated. Furthermore, the hydrocarbon group may contain one or more ring structures. It should be noted that the hydrocarbon group may have one or more heteroatoms, such as nitrogen atoms (N), oxygen atoms (O), sulfur atoms (S), phosphorus atoms (P), silicon atoms (Si), amide bonds, sulfonyl bonds, siloxane bonds, carbonyl groups, carbonyloxy groups, or structures containing heteroatoms, at its ends or in the molecular chain.

[0039] In the context of this specification, the substituent of the "hydrocarbon group" is not particularly limited, and examples thereof include halogen atoms; 1-6 Alkyl, C 2-6 Alkenyl, C 2-6 Alkynyl, C 3-10 Cycloalkyl, C 3-10 Unsaturated cycloalkyl, 5-10 membered heterocyclic group, 5-10 membered unsaturated heterocyclic group, C 6-10 Aryl and 5- to 10-membered heteroaryl groups.

[0040] In this specification, alkyl and phenyl groups may be unsubstituted or substituted unless otherwise specified. Substituents for these groups are not particularly limited, and examples thereof include halogen atoms, C 1-6 Alkyl, C 2-6 Alkenyl and C 2-6 One or more groups in an alkynyl group.

[0041] ·Ingredients (A)

[0042] The curable polyorganosiloxane composition of the present invention contains, as component (A), at least one polyorganosiloxane having two or more hydroxyl groups or hydrolyzable groups bonded to silicon atoms in one molecule. Component (A) serves as the base polymer of the curable polyorganosiloxane composition. The hydroxyl group or hydrolyzable group may be present at any position in the polyorganosiloxane molecule. For example, the hydroxyl group or hydrolyzable group may be present at a molecular terminal or as a side chain at a position other than a terminal terminal. In the case of a linear polyorganosiloxane, it is preferred that at least one hydroxyl group or hydrolyzable group be 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 bonded chain in the molecule of component (A).

[0043] The term "hydrolyzable group" refers to a group that is susceptible to hydrolysis, that is, a group that can be separated from the main structure of a compound by hydrolysis. Examples of hydrolyzable groups include -OR', -OCOR', -ON=CR'2, -NR'2, -NHR', and halogen atoms (in these formulas, R' represents a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms), with -OR' (i.e., an alkoxy group) being preferred. Examples of R' include unsubstituted alkyl groups such as methyl, ethyl, propyl, isopropyl, n-butyl, and isobutyl; and substituted alkyl groups such as chloromethyl. Among these, alkyl groups, particularly unsubstituted alkyl groups, are preferred, with methyl and ethyl groups being more preferred. The hydroxyl group is not particularly limited and may be a hydroxyl group generated by hydrolysis of a hydrolyzable group. Examples of halogen atoms include fluorine, chlorine, bromine, and iodine atoms, with chlorine being preferred.

[0044] The molecular skeleton of component (A) is not particularly limited as long as it is primarily composed of siloxane bonds. The siloxane skeleton may be interrupted by divalent organic groups. In this specification, when describing the structure of a siloxane compound, the structural units of the siloxane compound may be described using the following abbreviations. These structural units may be referred to as "M units," "D units," and so on.

[0045] M:-Si(CH3)3O 1 / 2

[0046] D:Si(CH3)2O 2 / 2

[0047] T:Si(CH3)O 3 / 2

[0048] Q:SiO 4 / 2

[0049] Hereinafter, in this specification, a siloxane compound is a compound constructed by combining the above-mentioned structural units, and may include a compound in which the methyl groups of the above-mentioned structural units are replaced by other groups such as halogens such as fluorine, hydrocarbon groups such as phenyl groups, etc. In this case, in order to express the state of being replaced by a substituent, the D unit replaced by a phenyl group may be expressed as D Ph In addition, for example, in D Ph 20 D 20 In the case of , this statement means that a total of 20 phenyl groups are contained in 40 D units. This statement does not mean that in 20 consecutive D Ph The unit is followed by 20 consecutive D units. It can be understood that each unit can be arranged arbitrarily and can contain SiPh2O 2 / 2 (expressed as D Ph2 ) Siloxane compounds can adopt various three-dimensional structures using T units or Q units, but component (A) can adopt a linear molecular skeleton formed by arbitrarily combining the above-mentioned M and D units.

[0050] In one embodiment of the present invention, component (A) may contain an average of two or more hydroxyl groups or hydrolyzable groups bonded to silicon atoms in one molecule and may be hydrolyzed by reacting with (B) described below via -OR 2 The compound forming the network structure by the condensation reaction of the groups is not particularly limited. Component (A) typically has at least two units represented by the general formula (1) in the molecule:

[0051] (R a ) s (R 3 ) t SiO （4-s-t） / 2 (1)

[0052] (Where,

[0053] R a is a hydroxyl group or a group capable of hydrolyzing;

[0054] R 3 It is a monovalent hydrocarbon group having no aliphatic unsaturated bond;

[0055] s is an integer from 1 to 3;

[0056] t is an integer from 0 to 2, where s+t is 1 to 3).

[0057] As a specific example of the component (A), a linear polyorganosiloxane represented by the following general formula (2) can be exemplified:

[0058] (R a )3-p R p Si-O-(Si(R) r (R a ) 2-r O) n -SiR q (R a ) 3-q ···(2)

[0059] (Where,

[0060] R a are each independently a hydroxyl group or a hydrolyzable group,

[0061] R is each independently a monovalent organic group,

[0062] p and q are each independently 0, 1 or 2,

[0063] r is each independently 0, 1 or 2,

[0064] (n is a number that sets the viscosity at 23°C to 0.1 to 500 Pa·s).

[0065] As R, a group having a hydrocarbon group, especially an alkyl group, an alkenyl group, or an aryl group is preferred. From the viewpoint of controlling physical properties such as the refractive index, at least a portion of R may be an aryl group such as a phenyl group. Polyorganosiloxanes in which all R are methyl groups are particularly preferred due to their ease of acquisition. As for the position of the curable functional group, polyorganosiloxanes in which r is 2 in the above formula (2), i.e., linear polyorganosiloxanes in which at least one curable functional group exists at each of the two ends of the molecule, are preferred. As such component (A), examples include polyorganosiloxanes in which both ends are represented by R a 3-m R 3 m SiO 1 / 2 The unit is closed and the middle unit is R 3 2SiO 2 / 2 Unit linear polyorganosiloxane (here, R a is a hydroxyl group or a group capable of hydrolysis, R 3 is a monovalent hydrocarbon group, and m is 0, 1 or 2).

[0066] As polyorganosiloxanes having hydroxyl groups or hydrolyzable groups bonded to silicon atoms, those in the above formula (2) where p and q are 0 or 1, i.e., polyorganosiloxanes having two or more hydroxyl groups or hydrolyzable groups at the molecular ends, are preferred. Commercially available polyorganosiloxanes can be used as this component (A). Alternatively, polyorganosiloxanes into which hydroxyl groups or hydrolyzable groups have been introduced through known reactions can be used. Component (A) can be distinguished based on the position and type of substituents, degree of polymerization, etc., and a single compound may be used, or a mixture of two or more compounds may be used. Since component (A) is a polyorganosiloxane, a mixture of polyorganosiloxanes having various degrees of polymerization may also be used.

[0067] The amount of component (A) is not particularly limited as long as it allows the curable polyorganosiloxane composition to have a workable viscosity. The amounts of other components can be appropriately set within the preferred ranges given below, based on the amount of component (A).

[0068] Component (B)

[0069] The crosslinking agent in the curable composition of the present invention is a crosslinking agent having at least two -OR groups bonded to Si atoms. 2 The compound containing a hydroxyl group or a partially hydrolyzed condensate thereof (hereinafter also referred to as a "crosslinking agent") is a compound that undergoes a crosslinking reaction (condensation reaction) with component (A), specifically, with the hydroxyl group or hydrolyzable group bonded to the Si atom of component (A). 2 Each occurrence is independently a hydrogen atom or a monovalent organic group, preferably a monovalent organic group. A monovalent organic group means a group containing a monovalent carbon atom. Examples of the monovalent organic group include, but are not limited to, monovalent hydrocarbon groups. The hydrocarbon group has the same meaning as above.

[0070] The crosslinker may have Si-OR 2 Other reactive functional groups other than the amino group may be omitted. However, from the perspective of crosslinking properties, it is preferred that no other reactive functional groups be present. In the present invention, other reactive functional groups include primary amino groups, epoxy groups, (meth)acryloyl groups, (meth)acryloyloxy groups, mercapto groups, isocyanate groups, and the like. The following descriptions of crosslinking agents are categorized into (B1) crosslinking agents without reactive functional groups and (B2) crosslinking agents with reactive functional groups.

[0071] <<(B1)Cross-linking agents without reactive functional groups>>

[0072] Examples of the cross-linking agent (B1) having no reactive functional group include: 1 n Si (OR 2 )4-n (Where R 1 Each occurrence is independently a substituted or unsubstituted monovalent hydrocarbon group, R 2 An organosilicon compound represented by (wherein each occurrence is independently a hydrogen atom or a monovalent organic group, and n is 0, 1 or 2).

[0073] R 1 Preferably, each occurrence is independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 12 carbon atoms. 1 Examples include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, heptyl, octyl, nonyl, and decyl; cycloalkyl groups such as cyclopentyl, cyclohexyl, and cycloheptyl; aryl groups such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups such as benzyl, phenylethyl, and phenylpropyl; alkenyl groups such as vinyl, allyl, propenyl, and butenyl; alkynyl groups such as ethynyl and propynyl; and groups in which some or all of the hydrogen atoms of these groups are substituted with halogen atoms such as fluorine, chlorine, and bromine (for example, chloromethyl, bromoethyl, chloropropyl, trifluoropropyl, and 3,3,4,4,5,5,6,6,6-nonafluorohexyl).

[0074] R 2 Each occurrence is independently a hydrogen atom or an alkyl or alkenyl group having 1 to 12 carbon atoms, which may have a -C(=O)-, -NR'- or -N=C(R')- group at the terminal, and one or more hydrogen atoms may be substituted by a halogen or alkoxy group (wherein R' is an alkyl group having 1 to 6 carbon atoms and may form a ring together with the carbon portion of the alkyl or alkenyl group). Specifically, CH3-, C2H5-, C3H7-, CF3CH2-, CH3CO-, CH2=C(CH3)-, CH3CH2C(CH3)=N-, (CH3)2N-, (C2H5)2N-, CH2=C(OC2H5)-, (CH3)2C=C(OC8H 17 )-,or

[0075] [Chemistry 1]

[0076] .

[0077] R 2 More preferred is a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms, and particularly preferred is CH 3 - or C 2 H 5 -.

[0078] n is preferably 1 or 2.

[0079] Examples of the crosslinking agent (B1) having no reactive functional group include a crosslinking agent further having at least one [Si(XOR g3 )(CH3)O] units and [Si(Rg4 ) (CH3) O] units, and these units are cyclically bonded to an organosilicon compound. Here, regarding the organic silicon compound containing OR g3 Units and units containing R g4 The units can be understood as the two existing alternately, and their arrangement order is arbitrary.

[0080] R g3 is a monovalent organic group, and as a specific R g3 , alkyl groups having 1 to 12 carbon atoms, preferably 1 to 4 carbon atoms, -Si(OR") 3-w R” w (Here, R" is an alkyl group having 1 to 4 carbon atoms, and w is an integer from 0 to 3). As a more specific example, R g3 Examples of the group include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, and tert-butyl groups, trimethoxysilyl, triethoxysilyl, dimethoxymethylsilyl, and diethoxyethylsilyl groups.

[0081] X is a single bond or a divalent alkylene group having 1 to 12 carbon atoms.

[0082] R g4 Each occurrence is independently a monovalent organic group. g4 It is preferably a substituted or unsubstituted monovalent hydrocarbon group, and more preferably a substituted or unsubstituted monovalent hydrocarbon group having 1 to 12 carbon atoms. g4 Examples include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, heptyl, octyl, nonyl, and decyl; cycloalkyl groups such as cyclopentyl, cyclohexyl, and cycloheptyl; aryl groups such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups such as benzyl, phenylethyl, and phenylpropyl; alkenyl groups such as vinyl, allyl, propenyl, and butenyl; alkynyl groups such as ethynyl and propynyl; and groups in which some or all of the hydrogen atoms of these groups are substituted with halogen atoms such as fluorine, chlorine, and bromine (for example, chloromethyl, bromoethyl, chloropropyl, trifluoropropyl, 3,3,4,4,5,5,6,6,6-nonafluorohexyl, etc.).

[0083] One molecule contains [Si(XOR g3 The number of [Si(R g4 )(CH3)O] units can also be 0, however, in [Si(XOR g3 When the number of )(CH3)O] units is 1, it is 1 or more. The [Si(XOR g3 )(CH3)O] units and [Si(R g4The total number of (CH 3 )O] units is preferably 2 or more and 4 or less.

[0084] Preferably, the cross-linking agent (B1) having no reactive functional group is a cross-linking agent having the formula: R 1 n Si (OR 2 ) 4-n The compound represented by (here, R 1 、R 2 and n as defined previously).

[0085] In a preferred embodiment, the cross-linking agent (B1) having no reactive functional group can be exemplified by alkoxy-containing compounds such as tetramethoxysilane, methyltrimethoxysilane, vinyltrimethoxysilane, decyltrimethoxysilane, phenyltrimethoxysilane, tetraethoxysilane, methyltriethoxysilane, vinyltriethoxysilane, phenyltriethoxysilane, tetrapropoxysilane, tetraisopropoxysilane, dimethyldimethoxysilane, vinylmethyldimethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane, 3-chloropropyltrimethoxysilane, and partially hydrolyzed condensates thereof; tetrakis(2-ethoxyethoxy)silane , compounds containing substituted alkoxy groups such as methyltri(2-methoxyethoxy)silane, vinyl(2-ethoxyethoxy)silane and phenyltri(2-methoxyethoxy)silane and partially hydrolyzed condensates thereof; compounds containing alkenyloxy groups such as methyltriacryloxysilane, methyltriisoacryloxysilane, vinyltriisoacryloxysilane, phenyltriisoacryloxysilane, dimethyldiisoacryloxysilane and methylvinyldiisoacryloxysilane and partially hydrolyzed condensates thereof; compounds containing acyloxy groups such as methyltriacetoxysilane and partially hydrolyzed condensates thereof; cyclic siloxane compounds represented by the following formula, etc.

[0086] [Chemistry 2]

[0087]

[0088] <<(B2)Cross-linking agents with reactive functional groups>>

[0089] The crosslinking agent (B2) having a reactive functional group is a compound that not only participates in the crosslinking reaction (condensation reaction) with component (A) but also functions as a thickener. As component (B2), a compound represented by the following formula can be used.

[0090] [Chemistry 3]

[0091]

[0092] In formula (B2), R g3 and R g4 Synonymous with above.

[0093] In formula (B2), R g6 Each occurrence represents R independently g8 -R g7 -.

[0094] R g7 Each occurrence of represents independently a single bond, an oxygen atom, or a divalent organic group. The divalent organic group is as shown above.

[0095] R g7 It is preferably an alkylene group having 1 to 10 carbon atoms, or a group having 1 to 10 carbon atoms and containing a nitrogen atom or an oxygen atom in the main chain.

[0096] R g7 More preferably:

[0097] an alkylene group having 1 to 3 carbon atoms,

[0098] CH2CH2-NH-CH2CH2CH2, or

[0099] CH2-O-CH2CH2CH2.

[0100] R g8 is a reactive functional group. g8 Preferably, each occurrence is independently a primary amino group, an epoxy group, a (meth)acryloyl group, a (meth)acryloyloxy group, a mercapto group or an isocyanate group, more preferably a primary amino group.

[0101] In formula (B2), ε4 is 2 or 3, more preferably 3. In formula (B2), ε5 is 0 or 1. In formula (B2), ε6 is 1 or 2, preferably 1. The sum of ε4, ε5, and ε6 is 4. Particularly preferably, ε4 is 3, ε5 is 0, and ε6 is 1.

[0102] Examples of the cross-linking agent (B2) having a reactive functional group include substituted or unsubstituted amino group-containing silanes such as 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltriisopropoxysilane, 3-aminopropyltriacetamidesilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, N-methyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, and N,N-dimethyl-3-aminopropyltrimethoxysilane; 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, and 3-glycidoxypropylmethyldimethoxysilane. , epoxy group-containing silanes such as 3,4-epoxycyclohexylethyltrimethoxysilane; isocyanate group-containing silanes such as 3-isocyanatepropyltrimethoxysilane, 3-isocyanatepropyltriethoxysilane, and 3-isocyanatepropylmethyldimethoxysilane; (meth)acryloyloxy group-containing silanes such as 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-acryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane; mercapto group-containing silanes such as 3-mercaptopropyltrimethoxysilane; and mixtures or reaction products of primary amino group-containing silanes and epoxy group-containing silanes.

[0103] A single crosslinking agent may be used, or two or more may be used simultaneously. When two or more crosslinking agents are used in combination, the combination may include two or more (B1), two or more (B2), or one or more (B1) and one or more (B2). From the perspective of crosslinking properties, the crosslinking agent (b) preferably contains at least one (B1).

[0104] In addition, when the crosslinking agent contains two or more of the formula: R 1 n Si (OR 2 ) 4-n In the case of an alkoxysilane represented by, it is preferred to use two alkoxysilanes having different n values ​​in the above formula. In this case, it is preferred that the smaller the n value, the greater the value of R. 1 and R 2 For example, when using a tetrafunctional alkoxysilane having an n value of 0 or a trifunctional alkoxysilane having an n value of 1, it is preferred that the R 1 and R 2 At least one of the carbon atoms is less than R of tetrafunctional alkoxysilane. 1 and R 2 The number of carbon atoms is preferably R1 and R 2 The carbon number of both is less than that of tetrafunctional alkoxysilane, etc. 1 and R 2 The carbon number.

[0105] The crosslinking agent may be contained in the curable composition in an amount of, for example, 0.1 parts by mass or more, specifically 0.3 parts by mass or more, and 30 parts by mass or less, specifically 20 parts by mass or less, and more specifically 10 parts by mass or less, based on 100 parts by mass of component (A).

[0106] The crosslinking agent can be contained in the curable composition in an amount of, for example, 0.1 to 30 parts by mass, specifically 0.3 to 10 parts by mass, and more specifically 0.3 to 5.0 parts by mass, based on 100 parts by mass of the component (A).

[0107] The crosslinking agent in the curable composition may contain 1 mol or more of -OR 2 The crosslinking agent may contain, for example, 30 moles or less of -OR 2 Specifically, the content of the group may be 20 mol or less, more specifically, 10 mol or less.

[0108] The crosslinking agent may contain -OR in the range of 1 to 30 mol, for example, based on 1 mol of the hydroxyl group or hydrolyzable group bonded to the Si atom of the component (A). 2 Specifically, the moiety can be contained in the range of 2 to 20 mol.

[0109] (Condensation Catalyst)

[0110] (C) The condensation catalyst is a component that promotes the hydrolysis and condensation of the component (A) and the crosslinking agent. Examples of the condensation catalyst include metal catalysts, organic acid catalysts, inorganic acid catalysts, and alkaline catalysts. From the perspective of the curing rate of the composition, metal catalysts are preferred.

[0111] Examples of the metal atom contained in the metal-based catalyst include titanium, zirconium, and tin, and organic tin compounds and titanium alkoxides are particularly preferred.

[0112] As one embodiment of the metal-based catalyst, a catalyst having an alkoxide (-OR h When a compound having an alkoxide is used as a metal catalyst, the above-mentioned R h, preferably an alkyl group with 1 to 4 carbon atoms. If such a catalyst is used, the condensation reaction is further promoted. When a compound having an alkoxide is used as a metal catalyst, as the above R h , more preferably an alkyl group having 1 to 3 carbon atoms. The use of such a catalyst significantly accelerates the condensation reaction. The catalyst is easily soluble or dispersed in the curable composition, promoting a uniform reaction. The catalyst also contributes to the formation of a transparent cured product of the curable composition with minimal foreign matter.

[0113] Preferred metal catalysts include carboxylic acid metal salts such as iron octoate, manganese octoate, zinc octoate, tin naphthenate, tin octoate, and tin oleate; organotin compounds such as dibutyltin diacetate, dibutyltin dioctoate, dibutyltin dilaurate, dibutyltin dioleate, diphenyltin diacetate, dibutyltin oxide, dibutyltin dimethanolate, dibutylbis(triethoxysilyl)tin, dioctyltin dilaurate, and dimethyltin dicedecanoate; tetraethyl titanate, tetrapropyl titanate, and tetramethyl titanate; Organic titanium compounds such as tetraisopropyl zirconate, tetra-n-butyl titanate, tetraisobutyl titanate, diisopropyl bis(ethyl acetoacetate) titanate, and 1,3-propanedioxytitanium bis(ethyl acetoacetate); organic aluminum compounds such as aluminum triacetylacetonate, tri(ethyl acetoacetate) aluminum, ethylaluminum diisopropyl acetoacetate, and triethoxyaluminum; organic zirconium compounds such as zirconium tetraacetylacetonate, tetraisopropyl zirconate, tetrapropyl zirconate, tetra-n-butyl zirconate, tetraisobutyl zirconate, zirconium tributoxyacetylacetonate, and zirconium tributoxystearate.

[0114] Examples of the organic acid catalyst include compounds having carboxylic acid, sulfonic acid, and phosphoric acid. Specific examples include acetic acid, trifluoroacetic acid, methanesulfonic acid, toluenesulfonic acid, and alkylphosphoric acid.

[0115] Examples of the inorganic acid catalyst include hydrochloric acid and sulfuric acid.

[0116] Examples of the base catalyst include ammonia, amine compounds such as triethylamine and diethylamine, dialkylhydroxyamines such as dimethylhydroxyamine and diethylhydroxyamine, tetramethylguanidine, and guanidino compounds such as silane or siloxane containing a guanidino group.

[0117] The curable composition of the present invention preferably contains 0.01 to 10.0 parts by mass of the condensation catalyst, more preferably 0.03 to 5.0 parts by mass, per 100 parts by mass of component (A).

[0118] Component (D)

[0119] The composition of the present invention contains a specific tackifier. Specifically, it contains a silicone-based tackifier, which is a compound having at least one tackifying functional group selected from a linear, branched, or cyclic aliphatic unsaturated hydrocarbon group, an epoxy group, an alkoxy group bonded to a silicon atom, and a hydrogen atom bonded to a silicon atom in one molecule, and further having at least one heteroatom in addition to the tackifying functional group in one molecule (excluding compounds corresponding to (A) or (B)).

[0120] As for the structure of the compound corresponding to component (D), in the simplest case, a compound having a structure in which the aforementioned adhesion-enhancing functional group is bonded to a functional group containing a heteroatom can be cited. Examples include 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-acryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, and 3-methacryloxypropylmethyldiethoxysilane. However, considering the need to improve adhesion and durability through molecular design, a preferred structure is one in which the adhesion-enhancing functional group is bonded to the organic molecule forming the main backbone of the compound via a spacer group. If heteroatoms exist outside the main backbone of the compound, that is, if there are reactive groups containing heteroatoms at the ends of the molecule, coupling with the condensation catalyst can sometimes affect curing properties, leading to poor curing. Therefore, a structure in which the adhesion-enhancing functional group is bonded via a spacer group in the molecular chain is preferred.

[0121] As the main skeleton of the compound corresponding to component (D), polyols, aromatic compounds, and heterocyclic compounds are preferably used because they can incorporate multiple viscosity-enhancing functional groups and can be easily designed to occupy equivalent positions in the molecular geometry. Furthermore, to maintain the symmetry of the compound, a portion capable of incorporating a spacer group is preferably present. To facilitate the introduction of a spacer group via substitution reaction, structures capable of forming ether or ester bonds are preferred, in addition to halogens and amines. Preferred structures for the main skeleton include the following, owing to the ease of obtaining the raw materials.

[0122] [Chemistry 4]

[0123]

[0124] represents a portion into which a spacer group is introduced. In addition, R represents hydrogen or methyl.

[0125] The spacer group is the moiety that connects the adhesion-promoting functional group to the main backbone. The location of the spacer group within the backbone is not particularly limited, as long as it is located somewhere other than at the end of the molecular chain. A heteroatom is preferably present within the backbone of the spacer group. Preferred examples of spacer groups include divalent alkylene groups substituted with at least one heteroatom for ease of design. However, if the spacer group is selected to introduce one heteroatom into the molecule, spacers without heteroatoms, such as divalent alkylene groups such as ethylene (-CH2-), can also be used. Regarding divalent alkylene groups, to ensure sufficient compatibility with silicones such as components (A) and (B), the alkylene group preferably has 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, and even more preferably 1 to 8 carbon atoms. The spacer group may have any structure, including linear, branched, or cyclic. Furthermore, from the perspective of molecular design, it is preferred that the adhesion-promoting functional group described below be present at the end of the spacer group.

[0126] Examples of heteroatoms include oxygen (O), nitrogen (N), sulfur (S), and phosphorus (P). These heteroatoms can be present in structures such as carbonyl, thiocarbonyl, and imine groups. These heteroatoms are preferably present in structures such as ether, thioether, amine, or phosphine. The heteroatom-containing compound as component (D) is preferably at least one selected from sulfur compounds, nitrogen compounds, and phosphorus compounds. To further enhance adhesion, at least one sulfur atom is more preferably present. When a heteroatom is present in the spacer group, its positional relationship is not particularly limited.

[0127] Component (D) has at least one adhesion-enhancing functional group selected from a linear, branched, or cyclic aliphatic unsaturated hydrocarbon group, an epoxy group, an alkoxy group bonded to a silicon atom, and a hydrogen atom bonded to a silicon atom. Although a single adhesion-enhancing functional group can contribute to imparting adhesion, it is preferred that two or more adhesion-enhancing functional groups be present in one molecule. An epoxy group or an alkoxy group bonded to a silicon atom is preferred. As component (D), it is further preferred that at least one SiR 5 3-n (OR 5 ) n Base (here, R 5 is a monovalent hydrocarbon group having no aliphatic unsaturated bond, and n is 1, 2 or 3) organosilicon compound. In this case, R is particularly preferably 5 It is a methyl group or an ethyl group. When the component (D) is an alkoxysilyl compound having the above-mentioned groups, a partial hydrolysis condensate thereof is also preferably used as the component (D).

[0128] Component (D) may have any organic group in addition to the above structure. For example, component (D) may further have one or more groups selected from aromatic hydrocarbon-containing groups, epoxy-containing groups, and aliphatic unsaturated hydrocarbon groups. Specific examples of component (D) include the compounds shown below, but are not limited to these compounds as long as they meet the above requirements.

[0129] [Chemistry 5]

[0130]

[0131]

[0132] The content of component (D) is in the range of 0.05 to 20 parts by mass relative to 100 parts by mass of component (A). This range allows for greater adhesion to the substrate. Using 0.05 parts by mass or more facilitates sufficient adhesion. Furthermore, by setting the content to 20 parts by mass or less, it is easier to maintain the concentration of components (A) and (B) in the composition appropriately, achieving an improved adhesion effect, suppressing surface resinification and cracking, and achieving a more fully cured state. A more preferred content range is 0.1 to 15 parts by mass, and even more preferably, 0.5 to 10 parts by mass.

[0133] Ingredient (E)

[0134] The composition of the present invention further comprises an inorganic filler in order to suppress the fluidity of the composition. Examples of the inorganic filler include reinforcing fillers such as fumed titanium oxide; oxides such as silica, diatomaceous earth, iron oxide, zinc oxide, titanium oxide, and aluminum oxide; carbonates such as calcium carbonate, magnesium carbonate, and zinc carbonate; silicates such as aluminosilicate, calcium silicate, and mica; talc; conductive fillers such as carbon black, copper powder, and nickel powder; and fillers obtained by treating their surfaces with a hydrophobizing agent. Among these, the inorganic filler is preferably silica, surface-treated silica, carbon black, or calcium carbonate, and more preferably silica or surface-treated silica.

[0135] The curable composition of the present invention particularly preferably comprises surface-treated silica as an inorganic filler. By using surface-treated silica, the fluidity of the composition can be suppressed, and mechanical strength can be imparted to the cured product of the composition. In this specification, so-called surface treatment refers to the use of a reactive compound with a silanol group on the silica surface, wherein the silanol group is processed into a covalent bond with other types of groups.

[0136] Examples of silica include fumed silica, calcined silica, silica aerogel, precipitated silica, and crushed silica. Of these, fumed silica is preferred because it can suppress the fluidity of the composition with a small amount and impart mechanical strength to the cured product of the composition. Surface-treated silica preferably has a BET specific surface area of ​​50 to 500 m 2 / g of silicon dioxide, more preferably 80 to 400m 2 / g of silica, more preferably 100 to 300 m 2 / g of silica.

[0137] Examples of surface treatment methods include the use of silazane compounds (hexamethyldisilazane, 1,3-divinyl-1,1,3,3-tetramethyldisilazane, 1,3-bis(chloromethyl)tetramethyldisilazane, 1,3-bis(3,3,3-trifluoropropyl)-1,1,3,3-tetramethyldisilazane, 1,3-diphenyltetramethyldisilazane, pentamethyldisilazane, 2,2,4,4,6,6-hexamethylcyclotrisilazane, octamethylcyclotetrasilazane, 1,1,3,3-tetramethyldisilazane, 2,4,6-trimethyl-2,4,6-trivinylcyclotrisilazane, The surface of the silica can be treated with silazane or chlorosilane compounds (such as hexamethyldisilazane, dimethyldimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane, decyltrimethoxysilane, hexadecyltrimethoxysilane, etc.), chlorosilane compounds (such as methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, etc.), octamethylcyclotetrasiloxane, and dimethylsiloxane oligomers. Among these, chemical treatment with silazane or chlorosilane compounds is preferred because it allows for hydrophobic treatment of the silica surface with a small amount of treatment. Hexamethyldisilazane and dimethyldichlorosilane are particularly preferred. Hexamethyldisilazane is preferred from the perspectives of the degree of treatment and the stability (inactivation) of the surface state after treatment. Surface treatment of silica can be performed by blending and kneading these surface treatment agents with silica during the preparation of the curable composition. Commercially available materials may also be used.

[0138] As an inorganic filler, it is preferred to use an inorganic filler having a primary particle diameter of 0.01 to 0.1 μm. By setting the primary particle diameter of the inorganic filler in the above range, a composition with further suppressed fluidity can be obtained. The primary particle diameter of the inorganic filler is preferably 0.02 to 0.08 μm, and more preferably 0.03 to 0.07 μm. The primary particle diameter is measured based on electron microscopy.

[0139] The amount of inorganic filler added can be sufficient to maintain the shape of the curable composition after application, and is preferably adjusted appropriately within this range. Specifically, the amount of inorganic filler is preferably 1 to 500 parts by mass, preferably 1 to 200 parts by mass, and more preferably 1 to 100 parts by mass, per 100 parts by mass of component (A). The inorganic filler may be used alone or in combination of two or more.

[0140] [Curable polyorganosiloxane composition]

[0141] The curable polyorganosiloxane of the present invention contains the above-mentioned components (A) to (E).

[0142] The polyorganosiloxane composition of the present invention has no particular limitations on its properties, as long as the components are uniformly mixed and have fluidity sufficient for application to a substrate. The viscosity can be appropriately adjusted using the resin and solvent described below for handling. Furthermore, the polyorganosiloxane composition can be a one-component composition in which all components are mixed, or a two-component composition in which component (B) and component (C) are separately blended. The choice between a one-component and a two-component composition can be appropriately made taking into account workability, curing conditions, and other factors, and the method for this is well known to those skilled in the art.

[0143] The curable polyorganosiloxane composition of the present invention may contain other known components as long as they do not impair its purpose or effects. Suitable additives include flame retardants, tackifiers other than (D), heat-resistance-imparting agents, diluents, organic solvents, and inorganic or organic pigments. Furthermore, siloxane resins other than components (A) and (B) may also be incorporated. Examples of such resins include polyorganosiloxanes having only one curable functional group and polyorganosiloxanes without curable functional groups, such as dimethylsiloxane. These resins can be used as diluents.

[0144] <Other resins>

[0145] The curable polyorganosiloxane composition may further contain a siloxane resin that does not correspond to the aforementioned components (A) or (B). Such a resin can also be used as a diluent for adjusting viscosity. Among the resins obtained from the aforementioned combination of M, D, T, and Q units, such a siloxane resin having no or only one hydroxyl group or hydrolyzable group can be used. In particular, a siloxane having only one hydroxyl group or hydrolyzable group, represented by the following formula, can be used:

[0146] (R a ) 3-p R p Si-O-(SiR2O) n -SiR3

[0147] (Where R a , R, p, n are as defined in general formula (2)),

[0148] or a siloxane having no hydroxyl group or hydrolyzable group represented by the following formula:

[0149] R3Si-O-(SiR2O) n -SiR3

[0150] (wherein, R and n are as defined in general formula (2)).

[0151] By using such a siloxane resin, the hardness of the curable polyorganosiloxane composition when cured can be controlled, the viscosity of the composition can be controlled, and a wide range of workability and required physical properties can be met.

[0152] 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, relative to 100 parts by mass of component (A).

[0153] Thickener

[0154] The curable polyorganosiloxane composition may further contain a tackifier other than (D). A tackifier is a component that improves the adhesion of the cured product of the composition to substrates such as glass, metal, and plastic. Examples of tackifiers 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 silicon-bonded hydrogen atom and a divalent aromatic group in one molecule, compounds having a silicon-bonded hydrogen atom and a reactive organic functional group in one molecule, and / or partially hydrolyzed condensates thereof (excluding compounds corresponding to (D)). Examples of metal alkoxides include aluminum alkoxides such as aluminum triethoxide, aluminum tripropoxide, and aluminum tributoxide; and titanium alkoxides such as titanium tetraethoxide, titanium tetrapropoxide, titanium tetraisopropoxide, titanium tetrabutoxide, titanium tetraisobutoxide, and titanium tetraisopropoxide. Organic thickeners include amino group-containing silanes, isocyanurates, and carbasilatrane compounds. Specific examples include tetraethoxysilane, tetramethoxysilane oligomers, vinyltrimethoxysilane, vinyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, and 3,4-epoxycyclohexylethyltrimethoxysilane.

[0155] As a thickening agent, for example, Si(OR 4 ) n Base (here, R 4 represents an alkyl group having 1 to 4 carbon atoms or a 2-methoxyethyl group; n is an integer of 1 to 4, and an organosilicon compound having an epoxy group-containing group when n is 1 to 3 and / or a partially hydrolyzed condensate thereof.

[0156] Specific examples of thickeners other than (D) 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 tetraisopropoxide; zirconium acylates such as zirconium octoate, zirconium tetra(2-ethylhexanoate), and zirconium stearate; zirconium alkoxides such as n-propyl zirconate and n-butyl zirconate (excluding zirconium chelates); and metal alkoxides such as zirconium chelates such as zirconium tributoxyacetylacetonate, zirconium dibutoxybis(ethyl acetoacetate), zirconium tetraacetylacetonate, zirconium monoacetylacetonate, and zirconium ethylacetoacetate. The combined use of other thickeners can further enhance adhesive strength.

[0157] The additional tackifier may be included 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, relative to 100 parts by mass of component (A). The tackifier may be used alone or as a mixture of two or more.

[0158] Solvents

[0159] The curable polyorganosiloxane composition may contain a solvent. In this case, the curable polyorganosiloxane composition can be dissolved in an appropriate solvent at a desired concentration according to its use and purpose. The concentration of the above-mentioned solvent can 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 composition. From the viewpoint of adjusting the viscosity of the curable composition, it is preferred to contain a solvent. By containing a solvent, the workability of the curable composition can be improved.

[0160] One embodiment of the present invention is an adhesive comprising the aforementioned curable polyorganosiloxane composition. In articles using the curable polyorganosiloxane composition of the present invention as an adhesive, the cured product of the composition and various substrates may have a bonding portion, and the shape of the portion is not limited. For example, one embodiment of a method for manufacturing an article comprising a bonding portion between a substrate and a cured product of the composition comprises: preparing a component comprising a substrate and a composition; applying the composition to the surface of the substrate; and curing the composition to bond the substrate and the cured product of the composition.

[0161] The material of the substrate to which the adhesive containing the curable polyorganosiloxane composition of the present invention is applied is not particularly limited. Examples of substrates include metals such as aluminum, copper, nickel, iron, steel, brass, and stainless steel; engineering plastics such as epoxy resins, polyester resins such as polyethylene terephthalate, and polybutylene terephthalate (PBT); polycarbonate resins, acrylic resins, polyimide resins, phenolic resins, polyamide resins, polyphenylene sulfide (PPS) resins, and modified polyphenylene ether (PPE) resins; and glass. Furthermore, if necessary, the walls of the voids may be primed according to conventional methods. The substrate's shape and thickness are also not particularly limited.

[0162] An adhesive comprising a curable polyorganosiloxane composition is applied to the surface of a component comprising a substrate at a predetermined thickness by methods such as dripping, pouring, casting, extrusion from a container, coating with a rod or roller, screen printing, dipping, brushing, spraying, and dispensing. These methods are well known to those skilled in the art. The composition may be applied uniformly and uniformly to the entire surface of the component, or may be applied unevenly or partially in lines, stripes, or dots. The composition is typically applied at a thickness of 0.01 to 3 mm, preferably 0.05 to 2 mm.

[0163] The composition can be applied to the object by methods such as pouring, dripping, casting, injection molding, or extrusion from a container, or by integral molding using transfer molding or injection molding. The composition is then allowed to cure at room temperature (e.g., 23°C), allowing simultaneous bonding to occur. The curing time is preferably one week or less, more preferably 72 hours or less, and particularly preferably 24 hours or less for production advantages.

[0164] Articles using the curable polyorganosiloxane composition of the present invention as an adhesive exhibit excellent durability, including water and oil resistance on the bonded surface. Therefore, they can meet the demand for silicone bonding of metals such as aluminum and aluminum die castings, and engineering plastics such as PBT and PET. These articles are particularly well-suited for various components in the fields of aircraft, automobiles, and electronic materials.

[0165] Example

[0166] The composition of the present invention will be described in more detail with reference to the following examples; however, the present invention is not limited to these examples.

[0167] (1) Preparation of moisture-curing silicone composition

[0168] The components in the composition shown in Table 1 were kneaded and mixed as shown below.

[0169] 800 g of (A) trimethoxysilyl-terminated polydimethylsiloxane with a viscosity of 20,000 mPas and 120 g of fumed silica surface-treated with 1,1,3,3,5,5,7,7-octamethylcyclotetrasiloxane were kneaded at room temperature for 20 minutes, followed by kneading under reduced pressure for 1 hour. Then, 200 g of trimethoxysilyl-terminated polydimethylsiloxane with a viscosity of 20,000 mPas was added and kneaded at room temperature for 20 minutes. Further trimethylsilyl-terminated polydimethylsiloxane was added and kneaded at room temperature for 20 minutes, followed by kneading under reduced pressure for 1 hour. Subsequently, the components listed in Table 1 were blended in the ratios listed and kneaded under reduced pressure for 20 minutes, followed by degassing to prepare a moisture-curable silicone composition. Compound 1 is a compound having the following structure.

[0170] [Chemistry 6]

[0171]

[0172] Compound 1 was synthesized as follows. To a 500 mL separable flask, 74.5 g of triallyl isocyanurate, 98 g of 3-mercaptopropyltrimethoxysilane, and 200 g of toluene were added in that order and stirred at room temperature for 10 minutes. 0.5 g of AIBN (azobisisobutyronitrile) was added and stirred at room temperature under a nitrogen atmosphere for 10 minutes. While stirring, the temperature was raised to 50°C and the reaction was continued for 6 hours.

[0173] Then, while continuing stirring, toluene, unreacted precursor, and 3-mercaptopropyltrimethoxysilane contained in the compound were removed at 120° C. and a vacuum degree of 10 mmHg or less for 3 hours. The mixture was cooled to room temperature to obtain Compound 1.

[0174] <Preparation of moisture-curable silicone composition>

[0175] As Examples 2 and 3, moisture-curable silicone compositions were prepared using the same procedure as in Example 1, except that the amount of Compound 1 was adjusted as shown in Table 1. Furthermore, as Examples 4 to 10, moisture-curable silicone compositions were prepared using the same procedure as in Example 1, except that the compound corresponding to (D) was replaced with the following compounds 2 to 8, and the added amounts were adjusted as shown in Table 1. Furthermore, moisture-curable silicone compositions for the comparative examples were prepared using the same procedure as in Example 1, except that the compound corresponding to (D) was not added (Comparative Example 1), 0.5 parts by mass of 1,3,5-tris(trimethoxysilylpropyl)isocyanurate was added instead of the compound corresponding to (D) (Comparative Example 2), and the amount of Compound 1 was adjusted to 20.41 parts by mass (Comparative Example 3).

[0176] Compound 2 is a compound having the following structure. Compound 2 was obtained by adjusting the raw material quantities using the same method as Compound 1. Compound 3, in which the number of epoxy groups was modified, was obtained from Compound 1 using the same method. Furthermore, Compounds 4 to 8 were obtained from Compound 1 using the same method by changing the substance that constitutes the main skeleton. Their respective structures are shown below.

[0177] [Chemistry 7]

[0178]

[0179]

[0180] (Evaluation method)

[0181] <Hardness (Type A hardness), tensile strength, and elongation>

[0182] The polyorganosiloxane composition was applied, formed into a 2 mm sheet, and then allowed to cure in an atmosphere of 23°C and 50% RH for 7 days to obtain a cured polyorganosiloxane composition. The hardness (initial hardness) of the resulting cured product was measured using a type A durometer. Furthermore, the tensile strength was measured in accordance with JIS K 6249. Furthermore, the elongation was measured in accordance with JIS K 6249.

[0183] <Surface drying time>

[0184] The polyorganosiloxane composition was applied to the surface of a 5 cm diameter aluminum dish cleaned with an organic solvent, and the time until the surface was confirmed to be dry by touching it with a finger was measured at 23°C and 50% relative humidity (RH).

[0185] <Shear bond strength>

[0186] The following method is used to evaluate shear bond strength. After applying the silicone composition to one end of a test piece and spreading it evenly, the other end of the test piece is bonded to form a 25 mm wide and 10 mm long bond surface. The test piece is secured with a clamp and placed in an oven set to the curing temperature and cured for the curing time. After returning the test piece to room temperature (23°C), the prepared test piece is measured using a tensile testing machine at a tensile speed of 10 mm / min. This is referred to as "tensile shear bond strength" (MPa). Details of the test are in accordance with JIS K 6249.

[0187] Cohesive failure rate

[0188] The cohesive failure rate is the percentage of adherends that exhibit no delamination or silicone layer failure at the interface between the two adherends during a shear strength test. A cohesive failure rate of 100% indicates sufficient bond strength (adhesion). After measuring the shear strength as described above under "Shear Strength," the area of ​​the silicone layer bonded to each adherend is divided by the applied area to determine the cohesive failure rate (area %). Details of the test are in accordance with JIS K6249.

[0189] <Test 1: Water resistance test>

[0190] The compositions of Examples and Comparative Examples were applied to glass, aluminum, copper, and PPS to measure shear strength and cohesive failure immediately after application (0 hours). The samples were then immersed in 70°C water or a 50°C sodium chloride aqueous solution (brine) and similar measurements were performed after 7 days and 14 days in 70°C water. The evaluation results are summarized in Tables 2 to 6.

[0191]

[0192]

[0193]

[0194]

[0195]

[0196] <Test 2: Oil resistance test>

[0197] Using the same method as in Test 1, the compositions of the Examples and Comparative Examples were applied to aluminum and mild steel and immersed in automotive transmission fluid (Toyota Auto Fluid T-IV) at 120°C. Shear strength and cohesive failure rate, which are indicators of adhesive strength, were measured after 100 hours and 240 hours for aluminum and 100 hours and 14 days for mild steel. The evaluation results are summarized in Tables 7 and 8.

[0198]

[0199]

[0200] Tables 2-6 show that in comparative examples lacking the component (D) specified in the present invention, the adhesive strength and cohesive failure rate of each substrate significantly decreased upon contact with water (salt water). However, the compositions of the present invention exhibited high adhesion to all substrates and high water resistance. Furthermore, by appropriately adjusting the amount of component (D), high adhesion and water resistance were also achieved for all substrates. This trend also persisted with contact with oil. Because silicone is compatible with oil, there are concerns about swelling caused by oil and a decrease in physical properties and adhesion due to additives contained in the oil. However, the compositions of the present invention maintained high adhesion even in the presence of oil. Overall, the compositions of the present invention demonstrate excellent adhesive properties for automotive interior structures, where contact with high-temperature oil is a high possibility.

[0201] Industrial applicability

[0202] The composition of the present invention is a moisture-curing silicone composition having high adhesion and excellent water resistance, salt water resistance, and oil resistance. According to the present invention, a moisture-curing silicone composition having excellent adhesion to various substrates that are frequently exposed to water or oil can be provided.

Claims

1. A moisture-curable silicone composition comprising: A polyorganosiloxane having two or more hydroxyl groups or hydrolyzable groups bonded to silicon atoms in one molecule; B Siloxane compounds having two or more -OR groups bonded to silicon atoms in one molecule 2 Base, here, R 2 Each occurrence is independently a hydrogen atom or a monovalent organic group; C condensation catalyst; D. A silicone-based tackifier, which is a compound having one or more tackifying functional groups selected from a group containing an aromatic hydrocarbon, a group containing an epoxy group, and a linear, branched, or cyclic aliphatic unsaturated hydrocarbon group in one molecule, and having at least one heteroatom in addition to the tackifying functional groups in one molecule, wherein: does not contain a compound equivalent to said A or B; and E inorganic filler, In the moisture-curable silicone composition, the content of the component D is 0.05 to 20 parts by mass relative to 100 parts by mass of the component A.

2. The moisture-curable silicone composition according to claim 1, wherein The component D is at least one selected from the group consisting of sulfur compounds, nitrogen compounds, and phosphorus compounds.

3. The moisture-curable silicone composition according to claim 1, wherein The D component has at least one SiR 5 3-n (OR 5 ) n The organic silicon compound and / or its partial hydrolysis condensate, wherein R 5 It is a monovalent hydrocarbon group having no aliphatic unsaturated bond, and n is 1, 2 or 3.

4. The moisture-curable silicone composition according to claim 3, wherein The component D further has one or more groups selected from the group consisting of an aromatic hydrocarbon-containing group, an epoxy-containing group, and an aliphatic unsaturated hydrocarbon group.

5. The moisture-curable silicone composition according to any one of claims 1 to 4, wherein The A component contains two terminal R a 3-m R 3 m SiO 1 / 2 The unit is closed and the middle unit is R 3 2SiO 2 / 2 Unit linear polyorganosiloxane, where R a is a hydroxyl group or a group capable of hydrolysis, R 3 It is a hydrogen atom or a monovalent hydrocarbon group having no aliphatic unsaturated bond, and m is 0, 1 or 2.

6. The moisture-curable silicone composition according to any one of claims 1 to 4, wherein Component B contains a compound represented by the following formula or a partial hydrolysis condensate thereof: R 1 n Si(OR 2 ) 4-n Where, R 1 Each occurrence is independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 12 carbon atoms, R 2 Each occurrence is independently a hydrogen atom, or an alkyl or alkenyl group having 1 to 12 carbon atoms, which optionally has a -C(=O)-, -NR'- or -N=C(R')- group at the terminal, and one or more hydrogen atoms may be substituted by a halogen or alkoxy group, wherein R' is an alkyl group having 1 to 6 carbon atoms, and optionally forms a ring together with the carbon portion of the alkyl or alkenyl group, n is 0, 1 or 2.

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