JP7540897B2 - Succinic anhydride group-containing cyclic organosiloxane, addition-curable silicone composition containing said succinic anhydride group-containing cyclic organosiloxane, and use thereof - Google Patents

Description

The present invention relates to a cyclic organosiloxane containing a succinic anhydride group, an addition-curable silicone composition containing the cyclic organosiloxane containing a succinic anhydride group, and uses thereof.

Addition-curing silicone adhesive compositions cure at room temperature or, if necessary, by heating, to develop adhesion to various adherends. Addition-curing silicones are used as adhesives and potting agents for in-vehicle electronic components, etc. In addition, adhesive assistants are used to improve adhesion to substrates. Patent Document 1 proposes an organosilicon compound that contains a hydrosilyl group (a hydrogen atom directly bonded to a silicon atom) and has bisphenol A in its skeleton as an adhesive assistant for fluorine-containing adhesives. Patent Document 2 proposes a cyclic organosiloxane that has a hydrolyzable silyl group and two or more succinic anhydride groups as an adhesive assistant for organosiloxane compositions.

JP 2002-114793 A JP 2013-32498 A

There is an increasing demand for adhesion of metals such as aluminum and aluminum die cast, and engineering plastics such as PPS, PBT, and PET with addition-curing silicone adhesive compositions. According to the findings of the present inventors, the adhesive assistants described in Patent Documents 1 and 2 do not function adequately as adhesive assistants. In other words, there is a problem in that silicone compositions containing the adhesive assistants described in Patent Documents 1 and 2 do not have sufficient adhesion to various engineering plastics including PPS and metals.

The present invention aims to provide a cyclic organosiloxane that functions as an adhesion promoter that has excellent adhesion to various substrates and gives a cured product with good appearance. The present invention also aims to provide an addition-curable silicone composition that contains the cyclic organosiloxane and that has excellent adhesion to various substrates and gives a cured product with good appearance.

（式中、
Ｒ^１は、独立して、フッ素原子を含有しない１価の炭化水素基であり、
Ｒ^２は、独立して、炭素原子数２～１０の２価の炭化水素基であり、
ａは、０又は１以上の整数であり、
ｂは、１以上の整数であり、
ｃは、１以上の整数であるが、但し、
ａ＋ｂ＋ｃが３以上の整数である）
［２］ａ＋ｂ＋ｃが３～８の整数である、［１］の無水コハク酸基含有環状オルガノシロキサン。
［３］［１］又は［２］の無水コハク酸基含有環状オルガノシロキサンを用いた、接着助剤。
［４］（Ａ）ケイ素原子に結合したアルケニル基を、分子中に２個以上有するポリオルガノシロキサン；
（Ｃ）白金系触媒；及び
（Ｄ）［１］又は［２］の無水コハク酸基含有環状オルガノシロキサン；
を含み、任意として、（Ｂ）ケイ素原子に直接結合した水素原子を、分子中に３個以上有するポリオルガノハイドロジェンシロキサンを含む、付加硬化型シリコーン組成物。
［５］［４］の付加硬化型シリコーン組成物を用いた、接着剤。 The present invention relates to the following [1] to [5].
[1] A cyclic organosiloxane containing a succinic anhydride group, represented by the following general formula (1):

(Wherein,
R ¹ is independently a monovalent hydrocarbon group containing no fluorine atoms,
^R2 is independently a divalent hydrocarbon group having 2 to 10 carbon atoms;
a is 0 or an integer of 1 or more;
b is an integer of 1 or more;
c is an integer of 1 or more, provided that
a+b+c is an integer of 3 or more.
[2] The succinic anhydride group-containing cyclic organosiloxane of [1], wherein a+b+c is an integer of 3 to 8.
[3] An adhesion promoter using the succinic anhydride group-containing cyclic organosiloxane of [1] or [2].
[4] (A) a polyorganosiloxane having two or more alkenyl groups bonded to silicon atoms in the molecule;
(C) a platinum-based catalyst; and (D) the succinic anhydride group-containing cyclic organosiloxane of [1] or [2];
and optionally, (B) a polyorganohydrogensiloxane having three or more hydrogen atoms directly bonded to silicon atoms in the molecule.
[5] An adhesive using the addition-curing silicone composition of [4].

The present invention provides a cyclic organosiloxane that functions as an adhesion promoter that provides excellent adhesion to a variety of substrates and a cured product with good appearance. The present invention also provides an addition-curable silicone composition that contains the cyclic organosiloxane and has excellent adhesion to a variety of substrates.

[Definition of terms]
The structural units of siloxane compounds may be represented by the following abbreviations (hereinafter, these structural units may be referred to as "M units", " ^DH units", etc.), respectively.
M :Si( _CH3 ) _{3O1 /2}
M ^H :SiH( _CH3 ) _{2O1/ 2}
M ^Vi :Si(CH=CH ₂ )(CH ₃ ) ₂ O _1/2
D :Si( _CH3 ) _{2O2/ 2}
D ^H :SiH( _CH3 )O2 _/2
D ^Vi :Si(CH= _CH2 )( _CH3 )O2 _/2
T :Si( _CH3 )O3 _/2
Q :SiO _4/2 (tetrafunctional)

In this specification, specific examples of groups are as follows.
Examples of the monovalent hydrocarbon group include an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, and an alkenyl group. Examples of the monovalent hydrocarbon group having no aliphatic unsaturated bond include the above-mentioned monovalent hydrocarbon groups other than the alkenyl group.

The alkyl group is a straight-chain or branched group having 1 to 18 carbon atoms, and examples thereof include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, an octyl group, a decyl group, a dodecyl group, a hexadecyl group, and an octadecyl group.
The cycloalkyl group is a monocyclic or polycyclic group having 3 to 20 carbon atoms, and examples thereof include a cyclopentyl group and a cyclohexyl group.
The aryl group is an aromatic group containing a monocyclic or polycyclic group having 6 to 20 carbon atoms, and examples thereof include a phenyl group and a naphthyl group.
The aralkyl group is an alkyl group substituted with an aryl group, and examples thereof include a 2-phenylethyl group and a 2-phenylpropyl group.
The alkenyl group is a straight-chain or branched group having 2 to 6 carbon atoms, and examples thereof include a vinyl group, an allyl group, a 3-butenyl group, and a 5-hexenyl group.
The monovalent hydrocarbon group may be unsubstituted or substituted with a substituent. Examples of the substituent include halogen atoms such as fluorine, chlorine, and bromine; and a cyano group. Examples of the monovalent hydrocarbon group substituted with a halogen atom include a chloromethyl group, a chlorophenyl group, and a 3,3,3-trifluoropropyl group. Examples of the monovalent hydrocarbon group substituted with a cyano group include a 2-cyanoethyl group.

Examples of monovalent hydrocarbon groups that do not contain fluorine atoms include the above-mentioned monovalent hydrocarbon groups that are unsubstituted or substituted with the above-mentioned substituents (excluding fluorine atoms).

The divalent hydrocarbon group is a group obtained by removing a hydrogen atom from the above-mentioned monovalent hydrocarbon group, and examples of the divalent hydrocarbon group include an alkylene group, a cycloalkylene group, an arylene group, an aralkylene group, and an alkenylene group.
The alkylene group is a straight-chain or branched group having 1 to 18 carbon atoms, and examples thereof include a methylene group, an ethylene group, a trimethylene group, a 2-methylethylene group, and a tetramethylene group.
The divalent hydrocarbon group may be unsubstituted or substituted with the substituents described above, but preferably does not contain a fluorine atom.

（式中、Ｒ^１、Ｒ^２、ａ、ｂ及びｃは、前記したとおりである） [Succinic anhydride group-containing cyclic organosiloxane]
The succinic anhydride group-containing cyclic organosiloxane (hereinafter also referred to as "cyclic organosiloxane") is represented by the following general formula (1).

(In the formula, R ¹ , R ² , a, b and c are as defined above.)

The succinic anhydride group-containing cyclic organosiloxane functions as an adhesion promoter for addition-curing silicone compositions that provide a cured product with excellent adhesion to various substrates and good appearance, particularly when cured at 150°C for 1 hour or 100°C for 2 hours. The succinic anhydride group-containing cyclic organosiloxane also functions as an adhesion promoter that provides a cured product with good appearance, particularly when cured at 150°C for 1 hour. That is, the cured product of the addition-curing silicone composition containing the adhesion promoter made of the succinic anhydride group-containing cyclic organosiloxane has a smooth surface and does not exude liquid to the surface. The succinic anhydride group-containing cyclic organosiloxane also functions as an adhesion promoter that provides a cured product with good appearance even after heating. That is, even when the cured product of the addition-curing silicone composition containing the adhesion promoter made of the succinic anhydride group-containing cyclic organosiloxane is further heated, it has an appearance with reduced yellowing.

The succinic anhydride group-containing cyclic organosiloxane may be a random copolymer, a block copolymer, or a combination thereof. In formula (1), a to c indicate the number of units defined by a to c present. In formula (1), the units defined by a to c may be the same or different.

R ¹ is independently a monovalent hydrocarbon group not containing a fluorine atom. R ¹ is preferably an alkyl group not containing a fluorine atom, more preferably an unsubstituted alkyl group, further preferably an unsubstituted alkyl group having 1 to 4 carbon atoms, and particularly preferably a methyl group.

^R2 is independently a divalent hydrocarbon group having 2 to 10 carbon atoms. ^R2 is preferably an alkylene group, and particularly preferably an ethylene group, a trimethylene group, or a 2-methylethylene group.

a is 0 or an integer of 1 or more. From the viewpoint of ease of synthesis and handling, a is preferably 0 or an integer of 1 to 3, and particularly preferably 0 or an integer of 1 to 2.

b is an integer of 1 or more. When b is an integer of 1 or more, the succinic anhydride group-containing cyclic organosiloxane has a hydrosilyl group (hydrogen atom directly bonded to silicon atom) that participates in the addition reaction. b is preferably an integer of 1 to 5, and particularly preferably an integer of 1 to 3, because it acts as a bridge between the silicone composition and various members to be bonded as a component that imparts adhesiveness, and in some cases, the cyclic organosiloxane component alone serves as a crosslinking point of the silicone composition. When b is 0, there is no bridging effect and the adhesiveness is poor. In other words, such a cyclic organosiloxane-containing silicone composition has poor function as an adhesive aid. On the other hand, a silicone composition containing a succinic anhydride group-containing cyclic organosiloxane in which b is an integer of 5 or less can obtain a cured product with excellent rubber elasticity.

c is an integer of 1 or more. When c is an integer of 1 or more, the cyclic organosiloxane contains a succinic anhydride group. c is preferably an integer of 1 to 3, and particularly preferably an integer of 1 to 2, in terms of the effect on storage stability due to compatibility with the silicone composition and adhesion to various members. When c is 0, adhesion is poor. In other words, such a cyclic organosiloxane-containing composition has poor function as an adhesive aid. Furthermore, a composition containing a cyclic organosiloxane containing a succinic anhydride group and c is 3 or less can give a cured product with improved heat resistance, appropriate hardness, and good adhesion to various members.

Moreover, a+b+c is an integer of 3 or more. When a+b+c is an integer of 3 or more, the main skeleton becomes a cyclic organosiloxane. From the viewpoint of ease of synthesis, a+b+c is preferably an integer of 3 to 8, and particularly preferably an integer of 3 to 6. That is, when a+b+c is an integer of 3 or more, the cyclic substance of D _a D ^H _{8-a that} can be used as a raw material can be easily synthesized. When a+b+c is an integer of 8 or less, when isolating D _a D ^H _8-a that can be used as a raw material, it becomes easy to separate and purify the target substance (D _a D ^H _8-a ) from a mixture of cyclic substances close to it (7-membered ring or 9-membered ring). As a result, a cyclic organosiloxane with high purity can be obtained.

(Uses of succinic anhydride group-containing cyclic organosiloxane)
The succinic anhydride group-containing cyclic organosiloxane can be used as an adhesion promoter to improve the adhesion of addition-curable silicone compositions, which are described below.

(Method for Producing Succinic Anhydride Group-Containing Cyclic Organosiloxane)
The succinic anhydride group-containing cyclic organosiloxane can be prepared by utilizing a method known to those skilled in the art or a similar method.The method for producing the succinic anhydride group-containing cyclic organosiloxane includes a method of reacting a cyclic siloxane having two or more hydrogen atoms directly bonded to silicon atoms with succinic anhydride having an unsaturated bond to obtain a siloxane having a structure represented by general formula (1).The reaction conditions, purification method, etc. can be appropriately selected by those skilled in the art. From the viewpoint of easily obtaining a product with high purity, and from the viewpoint of facilitating the synthesis and purification of a cyclic material containing hydrogen atoms directly bonded to silicon atoms, which is the raw material, preferred are methods for producing a cyclic organosiloxane containing succinic anhydride groups, in which a is 2, b is 1, c is 1, and a+b+c is 4, using a cyclic siloxane having two hydrogen atoms directly bonded to silicon atoms, where a is 2, b is 1, c is 1, and a+b+c is 4; using a cyclic siloxane having three hydrogen atoms directly bonded to silicon atoms, where a is 1 and a+b+c is 4; or using a cyclic siloxane having four hydrogen atoms directly bonded to silicon atoms, where a is 0 and a+b+c is 4.

[Addition-curable silicone composition]
The addition curing silicone composition (hereinafter, simply referred to as "silicone composition") contains the above-mentioned succinic anhydride group-containing cyclic organosiloxane. Because the silicone composition contains the succinic anhydride group-containing cyclic organosiloxane, it can achieve excellent adhesion to various substrates, particularly metals (aluminum, aluminum die cast, etc.) and engineering plastics (polybutylene terephthalate resin (PBT resin), polyphenylene sulfide resin (PPS resin), polyethylene terephthalate resin (PET resin), etc.).

The silicone composition is not particularly limited as long as it is a silicone composition capable of forming a crosslinked structure by utilizing an addition reaction between an alkenyl group bonded to a silicon atom and a hydrogen atom directly bonded to a silicon atom. Specifically, the silicone composition comprises the following components:
(A) a polyorganosiloxane having two or more alkenyl groups bonded to silicon atoms in the molecule;
(C) a platinum-based catalyst; and (D) the succinic anhydride group-containing cyclic organosiloxane;
and optionally containing (B) a polyorganohydrogensiloxane having three or more hydrogen atoms directly bonded to silicon atoms in the molecule (excluding component (D)).

In this specification, "(A) a polyorganosiloxane having two or more alkenyl groups bonded to silicon atoms in the molecule" is also referred to as "component (A)." The same applies to "(C) a platinum-based catalyst," etc.

In a silicone composition containing components (A), (C), and (D), and optionally containing component (B), an addition-curable silicone composition can be produced depending on the number of hydrosilyl groups in component (D) (i.e., b) and the number of alkenyl groups in component (A). Specifically, this is as follows:
(i) When the number of alkenyl groups in component (A) is 2 or more, the silicone composition can be made into an addition-curable silicone composition by further containing component (B). In this case, the value of b in component (D) can be 1 or more.
(ii) When the number of alkenyl groups in component (A) exceeds 2, an addition-curable silicone composition can be obtained by including component (D) in which the value of b is 2 or greater. In this case, the silicone composition may further include component (B), or may include component (D) in which the value of b is 1.
(iii) When the number of alkenyl groups in component (A) is 2, an addition-curable silicone composition can be obtained by including component (D) in which the value of b is 3 or greater. In this case, the silicone composition may further include component (B), and may also include component (D) in which the value of b is 1 or 2.
Such a silicone composition may be the following first, second or third silicone composition.

(First Silicone Composition)
The first silicone composition contains a cyclic organosiloxane containing a succinic anhydride group, in which b is an integer of 1. In this case, the first silicone composition contains (A1) a polyorganosiloxane having two or more alkenyl groups bonded to silicon atoms in the molecule; (B) a polyorganohydrogensiloxane having three or more hydrogen atoms directly bonded to silicon atoms in the molecule; (C) a platinum-based catalyst; and (D1) a cyclic organosiloxane containing a succinic anhydride group, in which b is an integer of 1.

In the first silicone composition, component (B) has three or more hydrogen atoms directly bonded to silicon atoms in the molecule, so even if b in component (D1) is an integer of 1, a cured product can be formed by a crosslinking reaction between components (A1) and (B). The first silicone composition may also contain (D) a cyclic organosiloxane containing a succinic anhydride group, in which b is an integer of 2 or more.

(Second Silicone Composition)
The second silicone composition contains a cyclic organosiloxane containing a succinic anhydride group, in which b is an integer of 2. In this case, the second silicone composition contains (A2) a polyorganosiloxane having more than two alkenyl groups bonded to silicon atoms in the molecule; (C) a platinum-based catalyst; and (D2) a cyclic organosiloxane containing a succinic anhydride group, in which b is an integer of 2.

The second silicone composition can form a cured product by a crosslinking reaction even if b is an integer of 2, because the number of alkenyl groups bonded to silicon atoms in component (A2) exceeds 2 in the molecule. The second silicone composition may further contain (D) a cyclic organosiloxane containing a succinic anhydride group, in which b is an integer of 1 or 3 or more. The second silicone composition may further contain (B) a polyorganohydrogensiloxane having three or more hydrogen atoms directly bonded to silicon atoms in the molecule.

(Third Silicone Composition)
The third silicone composition contains a cyclic organosiloxane containing a succinic anhydride group, in which b is an integer of 3 or greater. In this case, the third silicone composition contains (A1) a polyorganosiloxane having two or more alkenyl groups bonded to silicon atoms in the molecule; (C) a platinum-based catalyst; and (D3) a cyclic organosiloxane containing a succinic anhydride group, in which b is an integer of 3 or greater.

The third silicone composition can form a cured product by a crosslinking reaction between the (A1) and (D3) components because the number of hydrogen atoms directly bonded to silicon atoms in the (D3) component is 3 or more per molecule. The third silicone composition may also contain (D) a cyclic organosiloxane containing a succinic anhydride group, in which b is 1 or 2. The third silicone composition may also contain (B) a polyorganohydrogensiloxane having 3 or more hydrogen atoms directly bonded to silicon atoms per molecule.

The components contained in the first, second or third silicone composition are as follows.
<(A1) Polyorganosiloxane having two or more silicon-bonded alkenyl groups in the molecule>
(A1) Polyorganosiloxane having two or more alkenyl groups bonded to silicon atoms in the molecule (hereinafter also referred to as "(A1) alkenyl group-containing polyorganosiloxane") is a component that becomes the base polymer in the silicone composition. A network structure is formed in the cured product of the silicone composition by an addition reaction between the alkenyl group of the (A1) component and the hydrosilyl group (hydrogen atom directly bonded to a silicon atom) of the (B) or (D) component. The (A1) component is not particularly limited as long as it can form the network structure together with the (B) and/or (D) component. The (A) component is typically represented by the general formula (I):
(R ¹¹ ) _e (R ¹² ) _f SiO _(4-e-f)/2 (I)
(Wherein,
R ¹¹ is an alkenyl group;
R ¹² is a monovalent hydrocarbon group having no aliphatic unsaturated bonds,
e is an integer from 1 to 3;
f is an integer from 0 to 2, provided that e+f is 1 to 3.
The number of alkenyl groups bonded to silicon atoms in (A1) is preferably 2 to 100, and more preferably 2 to 50, in the molecule.

R ¹¹ is preferably a vinyl group from the viewpoint of ease of synthesis and fluidity of the silicone composition before curing. e is preferably 1 from the viewpoint of ease of synthesis. R ¹² is preferably a methyl group or a phenyl group from the viewpoint of ease of synthesis and excellent balance of properties such as mechanical strength and fluidity before curing, and is particularly preferably a methyl group. In addition, when applying the silicone composition before curing to a substrate, a polyorganosiloxane having only a methyl group and a polysiloxane having a phenyl group and a methyl group can be used in combination from the viewpoint of controlling fluidity and thixotropy.

The organic group bonded to the silicon atom of the other siloxane unit in component (A1) may be a monovalent hydrocarbon group that does not have an aliphatic unsaturated bond. For the same reasons as for ^R12 , the organic group is preferably a methyl group or a phenyl group, and is particularly preferably a methyl group.

R ¹¹ may be present either at the terminal or intermediate position of the molecular chain of component (A1), or may be present at both.

The siloxane skeleton of component (A1) can be linear or branched. That is, component (A) can be (A1-1) a linear polyorganosiloxane or (A1-2) a branched polyorganosiloxane.

The linear polyorganosiloxane (A1-1) may be a linear polyorganosiloxane in which both ends are blocked with R ₃ SiO _1/2 units and the intermediate unit is an R ¹² ₂ SiO _2/2 unit (wherein R is R ¹¹ or R ¹² , R ¹¹ is an alkenyl group, R ¹² is a monovalent hydrocarbon group having no aliphatic unsaturated bonds, and the molecule contains two or more R ^11s ). The R ₃ SiO _1/2 unit in the component (A1-1) is preferably an R ¹¹ R ¹² ₂ SiO _1/2 unit, an R ¹¹ ₂ R ¹² SiO _1/2 unit, or an R ¹¹ ₃ SiO _1/2 unit, and is particularly preferably an R ¹¹ R ¹² ₂ SiO _1/2 unit.

(A1-2) The branched polyorganosiloxane includes a branched polyorganosiloxane containing SiO _4/2 units and R ₃ SiO _1/2 units as essential units, and R ₂ SiO _2/2 units and/or RSiO _3/2 units as optional units. Here, R is R ¹¹ or R ¹² , and in R, at least two R ¹¹ per molecule. In order to become a crosslinking point in the curing reaction, it is preferable that at least three R per molecule are R ¹¹ , and the remainder are R ^12. From the viewpoint that the cured product of the silicone composition has excellent mechanical strength, the ratio of R ₃ SiO _1/2 units to SiO _4/2 units is preferably in the range of 1:0.8 to 1:3 in molar ratio, and is a solid or viscous semi-solid resin at room temperature.

In the component (A1-2), R ¹¹ may be present as R in an R ₃ SiO _1/2 unit, or as R in an R ₂ SiO unit or an RSiO _3/2 unit.

The viscosity of the (A1) component at 23°C is preferably 0.1 to 500 Pa·s, more preferably 0.3 to 300 Pa·s, and particularly preferably 0.5 to 200 Pa·s. When the viscosity of the (A1) component is in the above range, the adhesiveness to various substrates can be efficiently improved, the silicone composition in the uncured state exhibits good fluidity and excellent workability during casting and potting, and the cured product of the silicone composition exhibits excellent mechanical strength, appropriate elasticity and hardness. In addition, in order to further improve the adhesiveness even at room temperature, it is preferable that the viscosity of the (A1) component is high. Here, when the (A1) component is a combination of two or more types, the viscosity of the (A1) component means the viscosity of the mixed alkenyl group-containing polyorganosiloxane. In this specification, the viscosity is a value measured using a rotational viscometer in accordance with JIS K 6249, with the spindle number and rotation speed appropriately set, at 23°C.

The (A1) component may be one type or a combination of two or more types. For example, the (A1) component may be two or more types of (A1-1) linear alkenyl group-containing polyorganosiloxanes, or may be a mixture of one or more types of (A1-1) linear alkenyl group-containing polyorganosiloxanes and one or more types of (A1-2) branched alkenyl group-containing polyorganosiloxanes.

Component (A1) includes linear polyorganosiloxanes (in the above formulae, R is R ¹¹ or R ₁₂ , R ¹¹ is an _alkenyl group, R ¹² is a monovalent hydrocarbon group having no aliphatic unsaturated bonds, and contains two or more R ^11s in the molecule) that are terminated at both ends with R ¹¹ R ¹² ₂ SiO _1/2 units, the intermediate units being R ¹² ₂ SiO _2/2 units, and have a viscosity at ₂₃ °C of _0.1 to 500 ^{Pa·s, and branched polyorganosiloxanes (R is R 11 or R 12} _{, but} ^among R, at least three R per molecule are R ¹¹ , ^and the remainder are R ¹² ). It is particularly preferable that the component (A1) is a linear polyorganosiloxane having both ends blocked with ^Mvi units (dimethylvinylsiloxane units) and intermediate units consisting solely of D units (dimethylsiloxane units).

Component (A1) is not a component that corresponds to component (D). Component (A) preferably does not have any adhesion-imparting functional groups other than alkenyl groups bonded to silicon. In addition, it is particularly preferable that component (A1) does not have one or more groups selected from epoxy groups, alkoxy groups bonded to silicon, and hydrogen atoms bonded to silicon.

<(A2) Polyorganosiloxane having more than two alkenyl groups bonded to silicon atoms in the molecule>
(A2) Polyorganosiloxane having more than 2 alkenyl groups bonded to silicon atoms in the molecule is as described above for component (A1), including the preferred ones, except that it has more than 2 alkenyl groups bonded to silicon atoms in the molecule. (A2) component may be a mixture of a polyorganosiloxane having 3 or more alkenyl groups bonded to silicon atoms in the molecule and a polyorganosiloxane having 2 alkenyl groups bonded to silicon atoms in the molecule.

<(B) Polyorganohydrogensiloxane having three or more hydrogen atoms directly bonded to silicon atoms in the molecule>
The polyorganohydrogensiloxane (B) having three or more hydrogen atoms directly bonded to silicon atoms in the molecule (excluding component (D)) (hereinafter also referred to as "polyorganohydrogensiloxane (B)") is not particularly limited as long as it functions as a crosslinking agent for component (A).

The component (B) is typically represented by general formula (II):
(R ¹³ ) _g H _h SiO _(4-gh)/2 (II)
(Wherein,
R ¹³ is a monovalent hydrocarbon group having no aliphatic unsaturated bonds,
g is an integer from 0 to 2;
h is an integer from 1 to 3, provided that g+h is an integer from 1 to 3.
The molecule has three or more units represented by the following formula:

R ¹³ is preferably a methyl group from the viewpoint of ease of synthesis, and h is preferably 1 from the viewpoint of ease of synthesis.

From the viewpoint of ease of synthesis, it is preferable that component (B) has three or more siloxane units. In addition, from the viewpoints of not volatilizing even when heated to the curing temperature, and having excellent fluidity and ease of mixing with component (A), the number of siloxane units in component (B) is preferably 6 to 200, and particularly preferably 10 to 150.

The siloxane skeleton in component (B) may be linear, branched, or cyclic, with linear being preferred.

The component (B) is preferably (B1) a linear polyorganohydrogensiloxane in which both ends are each independently blocked with an R ¹⁴ ₃ SiO _1/2 unit and the intermediate unit is composed only of an R ¹⁴ ₂ SiO _2/2 unit, or (B2) a polyorganohydrogensiloxane composed only of R ¹⁴ ₃ SiO _1/2 units and SiO _4/2 units (in each of the above formulas, R ¹⁴ is each independently a hydrogen atom or a monovalent hydrocarbon group not having an aliphatic unsaturated bond, with the proviso that at least three of the R ^14s are hydrogen atoms). In the case of components (B1) and (B2), examples of the R ¹⁴ ₃ SiO _1/2 unit include HR ¹⁵ ₂ SiO _1/2 unit and R ¹⁵ ₃ SiO _1/2 unit, and examples of the R ¹⁴ ₂ SiO _2/2 unit include HR ¹⁵ SiO _2/2 unit and R ¹⁵ ₂ SiO _2/2 unit (in each of the above formulas, R ¹⁵ is a monovalent hydrocarbon group having no aliphatic unsaturated bond). In the case of component (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.

Examples of component (B) include: (B1-1) a linear polymethylhydrogensiloxane having both ends blocked with M units (trimethylsiloxane units) and intermediate units consisting only of D units (dimethylsiloxane units) and D ^H units (methylhydrogensiloxane units); (B1-2) a linear polymethylhydrogensiloxane having both ends blocked with M units (trimethylsiloxane units) and intermediate units consisting only of D units (dimethylsiloxane units) and D ^H units (methylhydrogensiloxane units), with 0.1 to 3.0 moles of methylhydrogensiloxane units per mole of dimethylsiloxane units; (B1-3) a linear polymethylhydrogensiloxane having both ends blocked with M ^H units (dimethylhydrogensiloxane units) and intermediate units consisting only of D ^H units (methylhydrogensiloxane units); (B1-4) a linear polymethylhydrogensiloxane having both ends blocked with M More preferred are linear polymethylhydrogensiloxanes in which the intermediate units are blocked with ^H units (dimethylhydrogensiloxane units) and the intermediate units consist only of D units (dimethylsiloxane units) and D ^H units (methylhydrogensiloxane units), with 0.1 to 3.0 moles of methylhydrogensiloxane units per mole of dimethylsiloxane units, and (B2-1) polymethylhydrogensiloxanes consisting only of M ^H units (dimethylhydrogensiloxane units) and Q units (SiO _2/2 units). It is particularly preferred that component (B) contains component (B-1) and/or component (B-2).
The component (B) may be one type or a combination of two or more types.

Component (B) is not a component that corresponds to component (D) and preferably does not have a succinic anhydride group. In addition, component (B) preferably does not have an ester bond and/or does not have one or more groups selected from an aliphatic unsaturated hydrocarbon group, an epoxy group, and an alkoxy group bonded to a silicon atom.

<(C) Platinum-based catalyst>
The platinum catalyst (C) is a catalyst for promoting the addition reaction between alkenyl groups and hydrosilyl groups in the silicone composition.

Examples of component (C) include platinum compounds such as chloroplatinic acid, reaction products of chloroplatinic acid and alcohols (for example, Lamoreaux's catalyst (platinum-octanol complex, U.S. Pat. No. 3,220,972)), platinum-olefin complexes, platinum-vinylsiloxane complexes, platinum-ketone complexes, and platinum-phosphine complexes. Of these, the reaction products of chloroplatinic acid and alcohols and platinum-vinylsiloxane complexes are preferred because of their good catalytic activity, and these are selected appropriately depending on the purpose of use.
The component (C) may be one type or a combination of two or more types.

<(D) Succinic Anhydride Group-Containing Cyclic Organosiloxane>
Examples of the succinic anhydride group-containing cyclic organosiloxane (D) include the following (D1), (D2), and (D3) depending on the number b.
(D1) Succinic anhydride group-containing cyclic organosiloxane (D2) where b is an integer of 2, and (D3) where b is an integer of 3 or more. Components (D1), (D2) and (D3) are as described above, including preferred embodiments, except that the number b is different. Each of the (D) components may be one type or a combination of two or more types.

<(E) Further Components>
The silicone composition may contain an additional component (E) other than the components (A) to (D) as long as the effects of the present invention are not impaired. Examples of such components include an inorganic filler (E1), a reaction inhibitor (E2), and various additives (E3). The additional components (E) may each be one type or a combination of two or more types.

<<(E1) Inorganic Filler>>
The silicone composition contains (E1) inorganic filler, and the cured product of the silicone composition is given high mechanical strength.(E1) inorganic filler includes reinforcing filler such as fumed silica, calcined silica, silica aerogel, precipitated silica, and fumed titanium oxide; and non-reinforcing filler such as diatomaceous earth, ground silica, aluminum oxide, zinc oxide, titanium oxide, aluminosilicate, calcium carbonate, calcium carbonate, magnesium carbonate, zinc carbonate, calcium silicate, talc, and ferric oxide, and is selected according to extrusion workability and the physical properties required for the cured product of the silicone composition.(E1) inorganic filler is preferably reinforcing filler, more preferably silica such as fumed silica, calcined silica, silica aerogel, and precipitated silica, and particularly preferably fumed silica.

When the (E1) inorganic filler is fumed silica, the BET specific surface area of the inorganic filler is preferably from 50 to 500 m ² /g, more preferably from 80 to 400 m ² /g, and particularly preferably from 100 to 300 m ² /g.

(E1) The inorganic filler may be treated with a surface treatment agent. Examples of such surface treatment agents include organoalkoxysilanes, organohalosilanes, siloxane oligomers, and organosilazanes.

<<(E2) Reaction Inhibitor>>
The reaction inhibitor (E2) is a component that inhibits the curing reaction rate of the silicone composition, thereby contributing to improved workability in handling and the balance between the development of adhesiveness and the curing rate. Examples of the reaction inhibitor (E2) include isocyanurates that have an aliphatic unsaturated hydrocarbon group and do not have an alkoxy group bonded to a silicon atom, such as triallyl isocyanurate, diallyl methyl isocyanurate, diallyl ethyl isocyanurate, tributenyl isocyanurate, and diallyl phenyl isocyanurate; organic compounds that have a polar group in the molecule, such as diallyl maleate; organic compounds that have an unsaturated bond, such as acetylene alcohols and derivatives thereof, such as 3,5-dimethyl-1-hexyn-3-ol; and the like.

<<(E3) Various Additives>>
Depending on the purpose, the silicone composition may further contain (E3) various additives such as (E3-1) an adhesion imparting agent, (E3-2) a polyorganohydrogensiloxane having two hydrogen atoms directly bonded to silicon atoms, an organic solvent, an inorganic pigment, an organic pigment, a thixotropy imparting agent, a viscosity modifier for improving extrusion workability, an ultraviolet protection agent, an antifungal agent, a heat resistance improving agent, a flame retardant, etc. Each of the various additives (E3) may be a single type or a combination of two or more types.

The adhesion promoter (E3-1) has two or more adhesion-imparting functional groups selected from an aliphatic unsaturated hydrocarbon group, an epoxy group, a polar group such as a carbonyl group or an isocyanuric group, an alkoxy group bonded to a silicon atom, and a hydrogen atom bonded directly to a silicon atom. The component (E3-1) is a component that imparts adhesion to various substrates to the composition, and can be appropriately selected from known adhesion promoters that can be applied to silicone compositions. However, the adhesion promoter (E3-1) is not the components (A) to (D), the component (E2), or the component (E3-2) described below.

(E3-2) polyorganohydrogensiloxane having two hydrogen atoms directly bonded to silicon atoms is as described above for component (B) except that there are two hydrogen atoms directly bonded to silicon atoms. Component (E3-2) is preferably a linear polymethylhydrogensiloxane in which both ends are blocked with M ^H units (dimethylhydrogensiloxane units) and the intermediate units are composed only of D units (dimethylsiloxane units). Component (E3-2) is not a component corresponding to component (D) and preferably does not have a succinic anhydride group. In addition, component (E3-2) preferably does not have an ester bond and/or does not have one or more groups selected from an aliphatic unsaturated hydrocarbon group, an epoxy group, and an alkoxy group bonded to a silicon atom.

[Content]
The content of each component in the silicone composition is preferably as follows.
The contents of the (B) and (D) components are not particularly limited as long as the silicone composition is cured, but the ratio {(H B +H D )/Vi _{A }} of the sum of the number of hydrogen atoms H _B directly bonded to silicon atoms in the (B) component and the number of hydrogen atoms H _D directly bonded to silicon atoms in the ( _D ) component to the number of _alkenyl groups Vi A in the ( _A ) component is preferably 0.1 or more and less than 10, more preferably 0.2 to 8.0, and particularly preferably 0.3 to 5.0. When {(H _B +H _D )/Vi _A } in the composition is 0.1 or more, the mechanical strength of the cured product is excellent, and when it is less than 10, the adhesiveness of the composition to various members is improved. When the silicone composition does not contain the (B) component, {(H _B +H _D )/Vi _A } is (H _D /Vi _A ).
Furthermore, the content of component ( _D ) is more preferably 0.1 to 20 parts by mass, even more preferably 0.5 to 10 parts by mass, and particularly preferably 1 to ₅ parts by mass, relative to ₁₀₀ parts by mass of component (A) in addition to being within the range satisfying the above-mentioned {(H B +H D )/Vi A }. When the content of component (D) is 0.1 part by mass or more relative to 100 parts by mass of component (A), the adhesion to various members is further enhanced, and when it is 20 parts by mass or less, the adhesion can be efficiently improved and the heat resistance can be improved.

The content of component (C) is a catalytic amount relative to the total amount of the silicone composition. Specifically, the content of component (C) is preferably 0.1 to 1,000 ppm by mass, and particularly preferably 0.5 to 200 ppm by mass, calculated as platinum metal atoms, relative to 100 parts by mass of the total composition. When the content of component (C) is within the above range, the curability is sufficient.

The content of the inorganic filler (E1) is preferably 0.1 to 60 parts by mass, and particularly preferably 1 to 45 parts by mass, per 100 parts by mass of the component (A). Such a content provides excellent extrusion workability and the resulting cured product has excellent mechanical strength. The content of the surface treatment agent can be appropriately determined depending on the specific surface area of the inorganic filler (E1) and the degree of surface treatment.

The content of the reaction inhibitor (E2) is preferably 0.001 to 20 parts by mass, and particularly preferably 0.01 to 10 parts by mass, per 100 parts by mass of component (A). Within this range, the effect of the reaction inhibitor can be efficiently exerted.

The amount of the (E) further component other than the (E1) and (E2) components is not particularly limited as long as it does not impair the intended use of the silicone composition.

(Method of Producing Silicone Composition)
The silicone composition can be produced by uniformly kneading the essential components (A), (C), and (D), as well as the optional components (B) and/or (E) using a mixing means such as a universal kneader or kneader.

(Preferred embodiment of the composition)
For stable long-term storage, the components (B) and (D) may be appropriately distributed and stored in two or more containers, with component (C) being stored in a separate container, and then mixed immediately before use.

(Uses of Silicone Composition)
The silicone composition has excellent adhesive properties to a variety of substrates and can therefore be used as an adhesive for a variety of substrates.

<Adhesion method>
The silicone composition can be attached to the object to be bonded by a method such as injection, dripping, casting, casting, extrusion from a container, or integral molding by transfer molding or injection molding, and cured, thereby simultaneously adhering to the object to be bonded. The curing conditions (i.e., heating temperature and heating time) can be appropriately adjusted according to the heat resistance temperature of the member to which the silicone composition is applied. From the viewpoint of the heat resistance and operability of the member to be bonded, the heating temperature is preferably 80 to 180°C, more preferably 80 to 150°C, and particularly preferably more than 100°C and 150°C or less. From the viewpoint of the simplicity of the curing process, the heating time is preferably 1 minute to 24 hours, more preferably 1 minute to 12 hours, and particularly preferably 1 minute to 8 hours.

The material of the object to be bonded is not particularly limited, and examples include metals such as aluminum, magnesium, nickel, iron, copper, etc., or alloys thereof (e.g., aluminum die-cast), and polymers such as ABS (acrylonitrile butadiene styrene resin), polycarbonate resin, PBT (polybutylene terephthalate resin), and PPS (polyphenylene sulfide resin).

(Application)
The composition can be used for mounting or sealing automotive and electrical/electronic parts, bonding semiconductors or general-purpose plastics, etc. Specifically, the composition can be used as a sealing material or potting material for automotive parts.

The present invention will be described in more detail below with reference to examples and comparative examples. In these examples, parts refers to parts by mass, and viscosity refers to viscosity at 23°C. The present invention is not limited to these examples.

(Ingredients used)
The components used in the examples and comparative examples are as follows.

(A) A mixture of alkenyl group-containing polyorganosiloxane A-1 and A-2 (amount of alkenyl groups bonded to silicon atoms: 0.25 mmol/g). A-1:A-2=75:25 (weight ratio).
A-1: A linear polymethylvinylsiloxane having both ends blocked with ^Mv units, consisting only of D units as intermediate units, and having a viscosity of 100 Pa·s at 23° C. A-2: A branched polymethylvinylsiloxane consisting only of M units, ^Dvi units, and Q units, with a molar unit ratio of M ₆ D ^vi Q ₈ (weight average molecular weight 5,000, an average of about 5 vinyl groups per molecule).
The weight average molecular weight is a value calculated in terms of styrene measured by GPC (gel permeation chromatography). The device used for measuring the weight average molecular weight is a Nihon Waters RI (differential refractometer) Model 2414 (mobile phase toluene).

(B) Polyorganohydrogensiloxane B: A linear polymethylhydrogensiloxane having both ends blocked with M units, intermediate units consisting only of D units and ^DH units, and a viscosity of 20 mPa·s at 23° C. (the amount of hydrogen atoms directly bonded to silicon atoms is 8.8 mmol/g).

(C) Platinum-based catalyst C: platinum-octanol complex (a complex having a platinum content of 4.0% by weight obtained by heating chloroplatinic acid with octanol)

(D) Succinic Anhydride Group-Containing Cyclic Organosiloxane The following succinic anhydride group-containing cyclic siloxane was used.

[Example 1 of Synthesis]
Synthesis of (D-1) 42g of toluene, 190.7g (0.749mol) of 2,2,4,6,8-pentamethyl-cyclotetrasiloxane, and 0.1g of alumina-supported platinum catalyst were charged into a 500ml flask equipped with a nitrogen gas inlet tube and a condenser, and the mixture was heated to 120°C while stirring under a nitrogen stream. 17.5g (0.125mol) of allylsuccinic anhydride (Tokyo Chemical Industry Co., Ltd.) was added dropwise over about 1 hour. Then, the mixture was reacted at 120°C for 12 hours to obtain a reaction solution. The reaction solution obtained was cooled to room temperature (23°C), activated carbon was added to adsorb the alumina-supported platinum catalyst, and the activated carbon was removed by filtration. Next, the reaction solution obtained was heat stripped under reduced pressure to remove toluene and unreacted components, and 47.7g of the target cyclic siloxane compound was obtained. The yield was 97%. Analysis by ¹ H-NMR revealed the following properties, confirming that the compound was the target compound.

[Example 2 of Synthesis]
Synthesis of (D-2) 83.8g of toluene, 381g (1.584mol) of 2,4,6,8-tetramethyl-cyclotetrasiloxane, and 1.6g of alumina-supported platinum catalyst were charged into a 1L flask equipped with a nitrogen gas inlet tube and a condenser, and the temperature was raised to 120°C while stirring under a nitrogen stream. 37g (0.264mol) of allylsuccinic anhydride (Tokyo Chemical Industry Co., Ltd.) was added dropwise over about 1 hour. Then, the mixture was reacted at 120°C for 34 hours to obtain a reaction solution. The reaction solution obtained was cooled to room temperature (23°C), activated carbon was added to adsorb the alumina-supported platinum catalyst, and the activated carbon was removed by filtration. Next, the reaction solution obtained was heat stripped under reduced pressure to remove toluene and unreacted components, and 91.2g of the target cyclic siloxane compound was obtained. The yield was 91%. Analysis by ¹ H-NMR revealed the following properties, confirming that the compound was the target compound.

[Example 3 of synthesis]
Synthesis of (D-3) 50g of toluene, 45g (0.187mol) of 2,4,6,8-tetramethyl-cyclotetrasiloxane, and 1.2g of alumina-supported platinum catalyst were charged into a 300ml flask equipped with a nitrogen gas inlet tube and a condenser, and the mixture was heated to 120°C while stirring under a nitrogen stream. 52.4g (0.374mol) of allylsuccinic anhydride (Tokyo Chemical Industry Co., Ltd.) was added dropwise over about 1 hour. Then, the mixture was reacted at 120°C for 6 hours to obtain a reaction solution. The reaction solution obtained was cooled to room temperature (23°C), activated carbon was added to adsorb the alumina-supported platinum catalyst, and the activated carbon was removed by filtration. Next, the reaction solution obtained was heat stripped under reduced pressure to remove toluene and unreacted components, and 92.2g of the target cyclic siloxane compound was obtained. The yield was 95%. Analysis by ¹ H-NMR revealed the following properties, confirming that the compound was the target compound.

(D') Comparative Compounds The following compounds were used: Here, for (D'-6), [3-(trimethoxysilyl)propyl]succinic anhydride manufactured by Tokyo Chemical Industry Co., Ltd. was used.

[Comparative Synthesis Example 1]
Synthesis of (D'-1) 440g of toluene, 1991.9g (7.42mol) of 2,2,4,6,6,8-hexamethyl-cyclotetrasiloxane, and 17.7g of alumina-supported platinum catalyst were charged into a 5L flask equipped with a nitrogen gas inlet tube and a condenser, and the mixture was heated to 120°C while stirring under a nitrogen stream. 1100g (7.42mol) of vinyltrimethoxysilane was added dropwise over about 1 hour. The mixture was reacted at 120°C for about 3 hours. The resulting reaction solution was cooled to room temperature (23°C), and the alumina-supported platinum catalyst was removed by filtration. The resulting reaction solution was stripped by heating under reduced pressure to remove toluene and unreacted components. The reaction product was then distilled under reduced pressure to obtain 400g of the desired cyclic siloxane compound. The yield was 13%. Analysis by ^1H -NMR revealed the following results, confirming that the product was the target compound.

[Comparative Synthesis Example 2]
Synthesis of (D'-2) 66g (0.471 mol) of allylsuccinic anhydride (Tokyo Chemical Industry Co., Ltd.), 50g of toluene, and 2.1g of alumina-supported platinum catalyst were charged into a 300ml flask equipped with a nitrogen gas inlet tube and a condenser, and the mixture was heated to 120°C while stirring under a nitrogen stream. 55g (0.205 mol) of 2,2,4,6,6,8-hexamethyl-cyclotetrasiloxane was added dropwise over about 2 hours. The mixture was allowed to react at 120°C for about 13 hours. The resulting reaction solution was cooled to room temperature (23°C), and activated carbon was added to adsorb the alumina-supported platinum catalyst, after which the activated carbon was removed by filtration. The resulting reaction solution was heat stripped under reduced pressure to remove toluene and unreacted components, and 110.5g of the target cyclic siloxane compound was obtained. The yield was 98%. Analysis by ¹ H-NMR revealed the following properties, confirming that the compound was the target compound.

[Comparative Synthesis Example 3]
Synthesis of (D'-3) 42g of toluene, 190.7g (0.749mol) of 2,2,4,6,8-pentamethyl-cyclotetrasiloxane, and 0.1g of alumina-supported platinum catalyst were charged into a 500ml flask equipped with a nitrogen gas inlet tube and a condenser, and the mixture was heated to 120°C while stirring under a nitrogen stream. 17.5g (0.125mol) of allylsuccinic anhydride (Tokyo Chemical Industry Co., Ltd.) was added dropwise over about 1 hour. Then, the mixture was reacted at 120°C for 12 hours to obtain a reaction solution. The reaction solution obtained was cooled to room temperature (23°C), and activated carbon was added to adsorb the alumina-supported platinum catalyst, after which the activated carbon was removed by filtration. Next, the reaction solution obtained was heat stripped under reduced pressure to remove toluene and unreacted components, and 50g of reaction product was obtained.

Next, 50 g of toluene, 68.3 g (0.461 mol) of vinyltrimethoxysilane, and 1.5 g of platinum catalyst supported on alumina were charged into a 500 ml flask equipped with a nitrogen gas inlet tube and a condenser, and the mixture was heated to 120° C. while stirring under a nitrogen stream. 49.5 g (0.125 mol) of the above reactant was added dropwise over about 2 hours. Then, the mixture was reacted at 120° C. for 10 hours to obtain a reaction solution. The reaction solution obtained was cooled to room temperature (23° C.), and activated carbon was added to adsorb the platinum catalyst supported on alumina, and the activated carbon was removed by filtration. The reaction solution obtained was stripped by heating under reduced pressure to remove toluene and unreacted components, and 84.8 g of the target cyclic siloxane compound was obtained. The yield was 98%. Analysis by ¹ H-NMR revealed the following results, and it was confirmed that the compound was the target compound.

[Comparative Synthesis Example 4]
Synthesis of (D'-4) 39g (0.162mol) of 2,4,6,8-tetramethyl-cyclotetrasiloxane, 40g of toluene, and 1g of alumina-supported platinum catalyst were charged into a 300ml flask equipped with a nitrogen gas inlet tube and a condenser, and the mixture was heated to 120°C while stirring under a nitrogen stream. 45.45g (0.324mol) of allylsuccinic anhydride (Tokyo Chemical Industry Co., Ltd.) was added dropwise over about 1 hour. The mixture was allowed to react at 120°C for about 5 hours. Furthermore, 96.2g (0.649mol) of vinyltrimethoxysilane was added dropwise over about 3 hours. The mixture was allowed to react at 120°C for 16 hours to obtain a reaction solution. The reaction solution obtained was cooled to room temperature (23°C), activated carbon was added to adsorb the alumina-supported platinum catalyst, and the activated carbon was removed by filtration. The resulting reaction solution was stripped under reduced pressure with heat to remove toluene and unreacted components, yielding 127.6 g of the target cyclic siloxane compound. The yield was 96%. Analysis by ¹ H-NMR revealed the following, confirming that it was the target compound.

[Comparative Synthesis Example 5]
Synthesis of (D'-5) 38.8g (0.161mol) of 2,4,6,8-tetramethyl-cyclotetrasiloxane and 0.8g of alumina-supported platinum catalyst were charged into a 200ml flask equipped with a nitrogen gas inlet tube and a condenser, and the temperature was raised to 120°C while stirring under a nitrogen stream. 23.9g (0.161mol) of vinyltrimethoxysilane was added dropwise over about 1 hour. Furthermore, 45.2g (0.322mol) of allylsuccinic anhydride (Tokyo Chemical Industry Co., Ltd.) was added dropwise over about 2 hours. The reaction was carried out at 120°C for 24 hours to obtain a reaction solution. The reaction solution obtained was cooled to room temperature (23°C), activated carbon was added to adsorb the alumina-supported platinum catalyst, and the activated carbon was removed by filtration to obtain 64.3g of the target cyclic siloxane compound. The yield was 60%. Analysis by ¹ H-NMR revealed the following properties, confirming that the compound was the target compound.

[Comparative Synthesis Example 6]
Synthesis of (D'-7) In a 200 ml flask equipped with a nitrogen gas inlet tube and a condenser, 41 g (0.17 mol) of 2,4,6,8-tetramethyl-cyclotetrasiloxane was added with 1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex of platinum so that the platinum metal concentration was 2.5 ppm, and reacted with 10 g (0.032 mol) of bisphenol A bisallyl ether. Unreacted 2,4,6,8-tetramethylcyclotetrasiloxane was removed by stripping to obtain 21 g of the target cyclic siloxane compound. Analysis by ¹ H-NMR revealed the following, confirming that this was the target compound.

(E1) Inorganic filler E1-1: Quartz powder (Crystallite VX-S, manufactured by Tatsumori Co., Ltd.)

(E2) Reaction inhibitor E2-1: Triallyl isocyanurate E2-2: 3,5-dimethyl-1-hexyn-3-ol

Example 1
(1) Preparation of Base Polymer (1) In the composition shown in Table 1, (A) alkenyl group-containing polyorganosiloxane and (E1) inorganic filler (E1-1) were charged into a universal kneader and stirred for 3 hours under reduced pressure at 150° C. After cooling to room temperature (23° C.), (E2) reaction inhibitor (E2-1 and E2-2) and (C) platinum catalyst were added and stirred for 15 minutes to prepare base polymer (1).
(2) Preparation of Addition-Curable Silicone Compositions Addition-curable silicone compositions were prepared in the compositions shown in Tables 2 to 4 by adding (B) a polyorganohydrogensiloxane and/or (D) a cyclic organosiloxane containing a succinic anhydride group, or (D') a compound for comparison to base polymer (1) and stirring the mixture.

（Ｃ）は、ベースポリマー中の白金量を１２ｐｐｍとなる量である。

(C) is an amount that results in a platinum content of 12 ppm in the base polymer.

(Evaluation Method)
<Hardness>
The addition-curable silicone composition was poured into a 6 mm thick Teflon (registered trademark) coated metal mold, covered with a similarly Teflon (registered trademark) coated metal lid, and cured in a hot air circulating dryer at 150°C for 1 hour. After cooling to room temperature (23°C), measurements were made in accordance with JIS K6249.

<Presence or absence of discoloration (yellow)>
The cured product used in the above "hardness" measurement was further heated in a hot air circulation dryer at 150°C for 72 hours, and the appearance (degree of yellowing) was observed and evaluated for the presence or absence and the degree of discoloration (yellowing) according to the following criteria.
◎: No change from the initial state. ◯: Slight yellowing was observed compared to the initial state. ×: Obvious yellowing was observed.

<Surface condition>
The addition-curable silicone composition was poured into a 2 mm thick Teflon (registered trademark) coated metal mold and cured in a hot air circulating dryer at 150°C for 1 hour. After cooling to room temperature (23°C) and 24 hours later, the surface condition was observed.
Good: The surface was smooth and no liquid oozed out when palpated. Bleeding: Oozing of liquid was observed on the cured surface.

<Shear adhesive strength>
The details of the test were in accordance with JIS K 6249. The silicone composition was applied to one end of the test piece and spread evenly, and then the other end of the test piece was attached to the other end so that the adhesive surface had a thickness of 1 mm, a width of 25 mm, and a length (overlap) of 10 mm, to obtain a test piece. The test piece was placed in an oven adjusted to the temperature of the curing conditions while being fixed with a jig, and cured in a hot air circulation dryer under the conditions of "150°C for 1 hour" or "100°C for 2 hours", and cooled to room temperature (23°C) to obtain a test piece. The test piece was measured with a tensile tester at a tensile speed of 10 mm/min, and the "tensile shear adhesive strength" (MPa) was obtained.

<Cohesive failure rate>
The cohesive failure rate is the rate at which the silicone layer is broken without peeling at the interface of the opposing adherends in the shear bond strength test. A cohesive failure rate of 100% indicates that the adhesive strength (adhesion) is sufficiently maintained. After measuring the shear bond strength according to the description of "shear bond strength" above, the area of the silicone layer adhered to each adherend was divided by the coating area to obtain the cohesive failure rate (area%).

<Adhesion test>
The silicone composition was applied to a specified member to a thickness of 2 mm, and cured at 100° C. for 2 hours. An incision was made with a knife at the interface between the member and the cured silicone composition, and the member was pulled in a 180° direction. The adhesion state was confirmed, and the adhesion was evaluated according to the following criteria.
◎: Cohesive failure △: Cohesive failure and interfacial peeling mixed ×: Interfacial peeling

The results are summarized in Tables 2, 3, and 4. In the tables, "(H _B +H _D )/Vi _A " varies depending on the presence or absence of the (B), (D), and (D') components. That is, in Example 1, "(H _B +H _D )/Vi _A " becomes "H _D /Vi _A ". In Example 2 and the like, "(H _B +H _D )/Vi _A " becomes "(H _B +H _D )/Vi _A ". In Comparative Example 1, "(H _B +H _D )/Vi _A " becomes "H _B /Vi _A ". In Comparative Example 2 and the like, "(H _B +H _D )/Vi _A " becomes "(H _B +H _D' )/Vi _A ". The value of "D unit (a)" in the components (D) and (D') means the number of D units per structural formula. The same applies to other groups.

The abbreviations in the table are as follows:
Aluminum: A1050P (JIS H 4000): Pure aluminum with an aluminum purity of 99.5% or more Aluminum die casting: ADC-12 (JIS H 5302:2006): Al-Si-Cu alloy PBT: Polybutylene terephthalate resin (manufactured by Polyplastics, DURANEX 2002)
PPS: Polyphenylene sulfide resin (Tosoh, Susteel GS-40%)

As is clear from Tables 2 to 4, the silicone compositions of the examples showed excellent adhesion to various substrates when cured at 150°C for 1 hour or 100°C for 2 hours. In addition, the silicone compositions of the examples gave cured products with good appearances when cured at 150°C for 1 hour, and yellowing of the cured products was suppressed after further heating at 150°C for 72 hours. Furthermore, the adhesive assistant of the examples was able to improve adhesion to various substrates by curing the silicone composition at 150°C for 1 hour or 100°C for 2 hours. In particular, the silicone composition containing the adhesive assistant of the examples was particularly excellent in cohesive failure rate for PPS, aluminum, and aluminum die casting when cured at 100°C for 2 hours, and in shear adhesive strength for PBT when cured at 100°C for 2 hours. Therefore, it can be seen that the succinic anhydride group-containing cyclic organosiloxane represented by general formula (1) is excellent as an adhesive assistant.

Comparing Example 3 with Example 6, when c was 1, the adhesion to various substrates (particularly the shear adhesive strength and cohesive failure rate to PPS when cured at 100°C for 2 hours, and the shear adhesive strength to PBT when cured at 150°C for 1 hour) was superior to when c was 2.

On the other hand, the compositions of Comparative Examples 1 to 8 did not contain (D), and therefore the compositions of Comparative Examples 1 to 8 had poor adhesion to various substrates or did not give cured products with good appearances. In particular, the compositions of Comparative Examples 1 to 8 had poor cohesive failure rates for PPS, aluminum, and aluminum die-cast when cured at 100°C for 2 hours, and poor shear adhesive strength to aluminum when cured at 100°C for 2 hours.
The composition of Comparative Example 1 contained only the crosslinking agent (B) as a component having a hydrogen atom directly bonded to a silicon atom, and therefore the composition of Comparative Example 1 had poor adhesion.
The composition of Comparative Example 2 contained a cyclic organosiloxane containing a hydrogen atom directly bonded to a silicon atom and containing no succinic anhydride group as an adhesion promoter, and therefore the composition of Comparative Example 2 had poor adhesion.
The composition of Comparative Example 3 contains a succinic anhydride group-containing cyclic organosiloxane that does not have a hydrosilyl group and has two succinic anhydride groups as an adhesive aid. Therefore, bleeding was observed in the cured product of the composition containing the adhesive aid of Comparative Example 3 under the curing condition of 150°C for 1 hour. In addition, the cured product of the composition containing the adhesive aid of Comparative Example 3 had poor adhesion.
The composition of Comparative Example 4 contains a succinic anhydride group-containing cyclic organosiloxane that does not have a hydrosilyl group as an adhesive aid. Therefore, bleeding was observed in the cured product of the composition containing the adhesive aid of Comparative Example 4 under the curing condition of 150°C for 1 hour. In addition, the cured product of the composition containing the adhesive aid of Comparative Example 4 was particularly poor in shear adhesive strength under the curing condition of 100°C for 2 hours.
The composition of Comparative Example 5 contains a succinic anhydride group-containing cyclic organosiloxane having two succinic anhydride groups as an adhesive aid. Therefore, bleeding was observed in the cured product of the composition containing the adhesive aid of Comparative Example 5 under the curing condition of 150°C for 1 hour. The cured product of the composition containing the adhesive aid of Comparative Example 5 was particularly poor in shear adhesive strength under the curing condition of 100°C for 2 hours.
The composition of Comparative Example 7 contains a succinic anhydride group-containing silane compound as an adhesive aid that does not have a hydrosilyl group and does not have a cyclic siloxane structure. Therefore, bleeding was confirmed in the cured product of the composition containing the adhesive aid of Comparative Example 7. In addition, the cured product of the composition containing the adhesive aid of Comparative Example 7 had poor adhesion to various substrates.
The composition of Comparative Example 8 contains, as an adhesive promoter, an organosilicon compound containing a hydrosilyl group and having in its skeleton bisphenol A. Therefore, the cured product of the composition containing the adhesive promoter of Comparative Example 8 had poor shear adhesive strength to various substrates (especially aluminum).
In addition, the compositions of Comparative Examples 3 and 5 to 8 were cured at 150°C for 1 hour, and after further heating at 150°C for 72 hours, the cured products showed significant yellowing and had poor appearances after heating.

Claims (3)

(A) a polyorganosiloxane having two or more alkenyl groups bonded to silicon atoms in the molecule;
(C) a platinum-based catalyst; and (D) a succinic anhydride group-containing cyclic organosiloxane represented by the following general formula (1):

(Wherein,
R ¹ is independently a monovalent hydrocarbon group containing no fluorine atoms,
R2 ^is independently a divalent hydrocarbon group having 2 to 10 carbon atoms;
a is 0 or an integer of 1 or more;
b is an integer of 1 or more;
c is an integer of 1 or more, provided that
a+b+c is an integer of 3 or more.
and optionally, (B) a polyorganohydrogensiloxane having three or more hydrogen atoms directly bonded to silicon atoms in the molecule. 2. The addition-curable silicone composition according to claim 1, wherein a+b+c is an integer from 3 to 8. An adhesive comprising the addition-curable silicone composition according to claim 1 or 2 .