Curable organopolysiloxane composition and adhesive composition containing same

Abstract

[Problem] To provide a curable organopolysiloxane composition that has high initial adhesive strength in a step such as temporary fixation and can be detached easily from a base material in a subsequent step, and a method for using the curable organopolysiloxane composition. [Solution] A curable organopolysiloxane composition containing: (A) an organosiloxane component including a specific silicon-atom-binding functional group that contains a (meth)acrylic group (RA), a resinous organosiloxane structural factor containing an alkenyl group, and a linear organopolysiloxane structural factor; (B) a siloxane component free of carbon-carbon multiple bonds in each molecule; and (C) a photoradical polymerization initiator. Additionally, the use of the curable organopolysiloxane composition.

Description

Curable organopolysiloxane composition and adhesive composition containing same

[0001] The present invention relates to a curable organopolysiloxane composition that contains, as a base, a siloxane component (which may be a copolymer or a mixture) containing (meth)acrylic functional groups and other aliphatic unsaturated carbon-carbon bond-containing groups, and that provides an adhesive layer with relatively strong initial adhesive strength upon a heat-curing reaction, and that, by carrying out a photo-curing reaction after the heat-curing reaction, changes the adhesive strength of the adhesive to a substrate between before and after the photo-curing reaction; an organopolysiloxane adhesive composition containing the same; and a method for using the same. In this invention, the adhesive includes so-called pressure-sensitive adhesives (PSAs).

[0002] Compared with acrylic-based or rubber-based pressure-sensitive adhesive compositions, organopolysiloxane pressure-sensitive adhesive compositions are excellent in electrical insulation, heat resistance, cold resistance, adhesion to various adherends, and transparency as needed, and therefore are widely used in the manufacture of semiconductor wafers and electronic / electrical devices such as smartphones and tablet PCs, and display devices such as displays. In particular, in recent years, in the processing of semiconductor wafers and the assembly processes of electronic / electrical devices and displays, components and protective films are temporarily fixed with relatively weak adhesive strength, and as the process progresses, the temporarily fixed components and the like are peeled from the adhesive to proceed, so there is a demand for compositions that form pressure-sensitive adhesives with weaker adhesion than conventional organopolysiloxane pressure-sensitive adhesive compositions.

[0003] In particular, in recent years, in the processing of semiconductor wafers, after the backside grinding process, adhesive sheets formed by applying an adhesive to a film substrate are used in the dicing / pickup / mounting process. However, these processes are divided into situations where adhesive strength is required and situations where easy peeling is required. That is, among these processes, in the backside grinding process of semiconductor wafers, the adhesive sheet must be sufficiently adhered to the semiconductor wafer without peeling in order to protect the patterned surface of the semiconductor wafer. Furthermore, after grinding, it must be easily peelable from the semiconductor wafer. Similarly, in the dicing process of semiconductor wafers, high adhesiveness is required so that the cut and separated element pieces do not peel off from the adhesive sheet. On the other hand, in the pick-up process, the cut and separated element pieces must be easily peeled off from the adhesive sheet. That is, the adhesive sheet must have low adhesiveness.

[0004] However, there is a trade-off between adhesive strength for the purpose of fixation and protection and the ease of peeling of components, and if a weak adhesive is used, the adhesive strength may be insufficient in processes requiring adhesive strength for temporary fixation, etc., which may cause process defects. On the other hand, if the adhesive strength is high, peeling may become difficult in subsequent processes, or process defects may occur due to adhesive residue caused by destruction of the cohesive layer. For this reason, there is a demand for adhesives that have sufficient adhesive strength for processes such as temporary fixation, and that can be very easily peeled from the substrate in subsequent processes.

[0005] Meanwhile, active energy ray-curable removable adhesives have been proposed in the fields of film materials, electrode materials, etc. (e.g., Patent Documents 1 to 3). These adhesives can significantly change their adhesive properties before and after active energy ray irradiation by using an acrylic copolymer or a polyurethane copolymer, and can exhibit high adhesive properties before active energy ray irradiation and high releasability after active energy ray irradiation. However, the adhesives described in these documents have an organic molecular skeleton, and therefore leave room for improvement, particularly in terms of heat resistance and durability, in applications where the purpose is to protect substrates during processing.

[0006] On the other hand, Patent Document 4 proposes an organopolysiloxane composition containing an organopolysiloxane compound having a (meth)acrylic functional group, a platinum catalyst, and a photoinitiator, which is capable of undergoing a curing reaction by photopolymerization and addition reaction, and which has excellent heat resistance, discoloration resistance, and low tack, and a sealant comprising the cured product of the organopolysiloxane composition.

[0007] However, these documents do not specifically disclose siloxane components containing (meth)acrylic functional groups and alkenyl groups, etc. (particularly, resin-linear structure-containing organopolysiloxane block copolymers and siloxane mixtures), and in particular, they do not describe or suggest anything about pressure-sensitive adhesive compositions containing such siloxane components or about the characteristics of their curing (particularly, two-stage curing and changes in adhesive strength).

[0008] In response to this, in order to solve the above problems, the present applicants have proposed a co-modified organopolysiloxane containing a (meth)acrylic functional group and an alkenyl group or the like, which has both heat curing and photocuring properties, and a curable organopolysiloxane composition containing the same (Patent Documents 5 and 6). With this composition, a pressure-sensitive adhesive layer, which is a semi-cured product, is formed by a heat curing reaction, and then completely cured by a photocuring reaction, whereby the adhesive strength of the pressure-sensitive adhesive layer to the substrate is significantly reduced after the photocuring reaction. However, the initial adhesive strength is not necessarily high, leaving room for further improvement.

[0009] Japanese Patent Application No. 2021-34958 (unpublished at the time of filing) Japanese Patent Application No. 2021-34959 (unpublished at the time of filing)

[0010] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a curable organopolysiloxane composition that provides a pressure-sensitive adhesive layer that has relatively strong initial adhesive strength and that can be very easily peeled from a substrate in a subsequent step, an organopolysiloxane pressure-sensitive adhesive composition containing the same, and a method for using the organopolysiloxane pressure-sensitive adhesive composition.

[0011] The present inventors have intensively investigated the above-mentioned problems and have arrived at the present invention. Specifically, the problems of the present invention can be achieved by a curable organopolysiloxane composition and an organopolysiloxane pressure-sensitive adhesive composition comprising: a main component: a siloxane component (which may be a resin-linear structure-containing organopolysiloxane block copolymer or a mixture of different organosiloxanes) that contains a silicon-bonded functional group containing a specific acrylic or methacrylic group and a silicon-bonded functional group containing at least one aliphatic unsaturated carbon-carbon bond, such as an alkenyl group, and that has a resinous organopolysiloxane structure and a linear siloxane structure; an adhesion-imparting component: a siloxane component that does not contain a carbon-carbon multiple bond in its molecule; and a photoradical polymerization initiator.

[0012] The curable organopolysiloxane composition of the present invention is both heat-curable and photocurable, and the pressure-sensitive adhesive layer, a semi-cured product formed by curing the composition through a heat curing reaction, has a relatively strong initial adhesive strength of 30 gf / 25 mm or more, and is then completely cured through a photocuring reaction, whereby the adhesive strength of the pressure-sensitive adhesive layer to the substrate is significantly reduced compared to before and after the photocuring reaction. As a result, the pressure-sensitive adhesive layer of the present invention has sufficient adhesive strength after heat curing, and can then be photocured by irradiation with high-energy rays, thereby reducing the adhesive strength and achieving easy peelability.

[0013] The present invention can provide a curable organopolysiloxane composition that has both heat-curing and photo-curing properties, and in which the semi-cured product after heat-curing has a relatively strong initial adhesive strength of 30 g / 25 mm or more, and in which the cured product after the photo-curing reaction has the property of being extremely easily peelable from a substrate; an organopolysiloxane pressure-sensitive adhesive containing the same; and a method for using the same.

[0014] In particular, the curable organopolysiloxane composition according to the present invention has a viscosity that allows application, excellent curability, and can provide a cured product (particularly a cured film) that has good adhesion to a substrate and excellent transparency upon curing reaction. Furthermore, the present invention makes it possible to realize a silicone-based pressure-sensitive adhesive layer / adhesion layer whose adhesive strength changes before and after the photocuring reaction, and can provide uses as protective members in a wide range of applications, as well as manufacturing methods and protection methods including equipment or devices equipped with the same.

[0015] The curable organopolysiloxane composition according to the present invention contains: (A) an organosiloxane component (selected from (A1) a resin-linear structure-containing organopolysiloxane block copolymer and (A2 / A3) an organosiloxane mixture) having one or more specific types of silicon-bonded (meth)acrylic groups and alkenyl groups, and having a resinous organopolysiloxane structure and a linear siloxane structure within the component; (B) a siloxane component containing no carbon-carbon multiple bonds within the molecule; and (C) a photoradical polymerization initiator. Preferably, the composition may further contain: (D) a specific MQ-type organopolysiloxane resin containing alkenyl groups; (E) an organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms within the molecule; (F) a hydrosilylation reaction catalyst; and a cure retarder, an organic solvent, and other optional components.

[0016] In addition, in the present specification, the term "(meth)acrylic group" means "acrylic group or methacrylic group." Each component will be explained below.

[0017] [Component (A)] Component (A) is the main component of the composition and is a siloxane component containing a silicon-bonded functional group containing a (meth)acrylic group and a silicon-bonded functional group containing at least one aliphatic unsaturated carbon-carbon bond, such as an alkenyl group, and having a resinous organopolysiloxane structure and a linear siloxane structure within the component. In component (A), the silicon-bonded functional group containing a (meth)acrylic group must be bonded to the resinous organopolysiloxane structure, but the alkenyl group may be present within the same molecule or in another siloxane component. That is, component (A) may be a co-modified resin-linear structure-containing organopolysiloxane block copolymer having these functional groups in the same molecule, or may be an organosiloxane mixture that includes a resinous organopolysiloxane containing a (meth)acrylic group and further includes a linear or resinous organopolysiloxane having other functional groups.

[0018] More specifically, component (A) is one or more (meth)acrylic group-containing organosiloxane components selected from the following components (A1) to (A3): component (A1) is a resin-linear structure-containing organopolysiloxane block copolymer, component (A2) is a mixture of (A2-1) a resinous organopolysiloxane containing (meth)acrylic groups and alkenyl groups and (A2-2) a linear organopolysiloxane having two alkenyl groups per molecule, and component (A3) is a mixture of (A3-1) a (meth)acrylic group-containing resinous organopolysiloxane, (A3-2) an alkenyl-containing resinous organopolysiloxane, and (A3-3) a linear organopolysiloxane having two alkenyl groups per molecule. Here, the linear organopolysiloxane (A2-2 / A3-3) having two alkenyl groups per molecule may be a linear organopolysiloxane having alkenyl groups only at both molecular chain terminals, and functions as an intermolecular chain extender during the curing reaction. Components (A2-1), (A3-1), and (A3-2) are MQ-type resinous organopolysiloxanes, as described below. However, they may contain monoorganosiloxy units (T units), diorganosiloxy units (D units), and small amounts of hydrolyzable groups such as hydroxyl groups (silanol groups) and alkoxy groups, provided that the technical effects are not impaired. Alternatively, they may be resinous organopolysiloxanes in which the content of hydroxyl groups or hydrolyzable groups has been reduced by hydrolyzing these hydrolyzable groups with a silylating agent such as trimethylsilane.

[0019] The component (A) as a whole contains silicon-bonded functional groups (R Ａ ), and an alkenyl group. Ａ) is a functional group that exhibits photocurability upon irradiation with high-energy rays in the presence of a photoradical polymerization initiator, and the alkenyl group is a functional group that exhibits heat curability in the presence of a hydrosilylation reaction catalyst. Because the curable organopolysiloxane composition according to the present invention contains both heat-curable and photo-curable silicon-bonded functional groups in component (A), the adhesive layer formed from the semi-cured product after the heat curing reaction has high initial adhesive strength when used in combination with component (B), which will be described later, and also exhibits a significant decrease in adhesive strength and easy peelability when the semi-cured product is irradiated with high-energy rays.

[0020] Furthermore, because component (A) as a whole comprises a linear organopolysiloxane structure, a resinous organopolysiloxane structure containing (meth)acrylic groups, and a resinous organopolysiloxane structure having alkenyl groups, the semi-cured product obtained by heat curing exhibits appropriate hardness and flexibility and is suitable for use as an adhesive. That is, the components (A1) to (A3) that can be used as component (A) differ in whether a block copolymer in which the above structural factors and functional groups are concentrated in the same molecule is selected as the base component, or a mixture of siloxane raw materials possessing the respective characteristics is selected as the base component. The technical effects of the present invention are achieved by using a base component possessing these characteristics as component (A).

[0021] Here, the silicon atom-bonded functional group (R Ａ ) is represented by the general formula (1): In the formula, R １ are each independently a hydrogen atom, a methyl group, or a phenyl group, and are preferably a hydrogen atom or a methyl group to form an acrylic or methacrylic group moiety. Z is a divalent organic group which may contain a heteroatom and is bonded to a silicon atom constituting the main chain of the polysiloxane represented by *, and may be a divalent organic group which may contain an oxygen atom, a nitrogen atom, or a sulfur atom.

[0022] Specifically, Z is an alkylene group having 2 to 22 carbon atoms, -R ３ -C(=O)-OR ４ - {wherein R３ is an alkylene group having 2 to 22 carbon atoms, and R ４ is a group selected from an ethylene group, a propylene group, a methylethylene group, or a hexylene group; and １ -X-C(=O)-X-Z ２ a divalent organic group represented by the formula - {wherein Z １ Ha -O(CH ２ ) ｋ - (k is a number ranging from 0 to 3), and X represents an oxygen atom, a nitrogen atom, or a sulfur atom. ２ is bonded to a silicon atom constituting the main chain of polysiloxane, where * is -[(CH ２ ) ２ O] ｍ (CH ２ ) ｎ -(m is a number in the range of 0 to 3, and n is a number in the range of 3 to 10)}.

[0023] Particularly preferably, the silicon atom-bonded functional group (R Ａ ) is represented by the general formula (1-1): In the formula, R １ R each independently represents a hydrogen atom, a methyl group, or a phenyl group, and is preferably a hydrogen atom or a methyl group. ２ are each independently an alkyl group or an aryl group, and from an industrial standpoint, an alkyl group having 1 to 20 carbon atoms or a phenyl group is preferred, and a methyl group is particularly preferred. １ Ha -O(CH ２ ) ｍ - (m is a number ranging from 0 to 3), and m is preferably 1 or 2. Z ２ is bonded to a silicon atom constituting the main chain of polysiloxane, where * is —(CH ２ ) ｎ - (n is a number ranging from 3 to 10), and those in which n is 2 to 6 are practically preferred. ＡThe (meth)acrylic functional group can be introduced into a molecule by reacting a silicon-bonded functional group containing at least one alkenyl group with a hydrosilane compound having a silicon-bonded hydrogen atom and a (meth)acrylic functional group in the molecule (e.g., 3-(1,1,3,3-tetramethyldisiloxanyl)propyl methacrylate, etc.) in the presence of a hydrosilylation catalyst. This reaction may, and preferably, be carried out in the presence of a polymerization inhibitor such as dibutylhydroxytoluene (BHT).

[0024] The alkenyl group in component (A) is preferably an alkenyl group having 2 to 20 carbon atoms, and examples thereof include a vinyl group, an allyl group, a butyl group, and a hexenyl group. From the standpoint of crosslinking reactivity, a vinyl group or a hexenyl group is preferred.

[0025] The component (A1) is R Ａ a R Ｂ （３－ａ） SiO １／２ (R Ａ is a silicon-bonded functional group containing an acrylic or methacrylic group, and R Ｂ is R Ａ and a is a number ranging from 1 to 3). ＲＡ Units), R Ｂ´ ３ SiO １／２ (R Ｂ´ is R Ａ is a monovalent organic group other than Ｂ´ at least one of which is an alkenyl group Ａｌｋ units) and SiO ４／２ and a resinous organosiloxane block X having an acrylic or methacrylic group, which comprises siloxane units (Q units) represented by the formula {R Ｃ ２ SiO ２ / ２} β (R Ｃis a monovalent organic group, and β is a number of 2 or greater), and a linear organosiloxane block Y having siloxane units represented by the formula (A1), and the block Y has at least two alkenyl groups per molecule. The mass ratio of block X to block Y in component (A1) may be within a range of 1:99 to 80:20, and preferably within a range of 20:80 to 60:40.

[0026] Regarding the resinous organosiloxane block X, R in the above formula Ｂ and R Ｂ´ is the above-mentioned R Ａ and examples thereof include monovalent hydrocarbon groups selected from alkyl groups, alkenyl groups, aryl groups, aralkyl groups, and halogenated alkyl groups in which some of the hydrogen atoms are substituted with halogen atoms such as fluorine atoms. Ｂ´ At least one of R is an alkenyl group. Ｂ may be an alkyl group (including, in particular, a methyl group) or a phenyl group, and R Ｂ´ At least one of R may be an alkenyl group having 2 to 8 carbon atoms (C2-C8 alkenyl), preferably a vinyl group or a hexenyl group, and the other R Ｂ´ may be an alkyl group (including, in particular, a methyl group) or a phenyl group; a is a number ranging from 1 to 3, preferably 1;

[0027] Furthermore, the resinous organosiloxane block X may be R Ｂ´´ ３ SiO １／２ (R Ｂ´´ is an alkyl group or a phenyl group), and industrially, the M unit is ３ ) ３ SiO １／２ It may be.

[0028] The resinous organosiloxane block X constituting component (A1) is the same as that of the above M ＲＡ Unit, M Ａｌｋ units, optionally M units and Q units, and ＲＡ Units and MＡｌｋ The sum of the amounts of the units is preferably in the range of 0.5 to 2.0 moles. ＲＡ The unit is R Ａ (CH ３ ) ２ SiO １／２ M Ａｌｋ The unit is (C2-C8 alkenyl) (CH ３ ) ２ SiO １／２ In addition, in the resinous organosiloxane block X, the ratio of M to 1 mole of Q units may be ＲＡ From the viewpoint of reactivity, it is particularly preferable that the amount of the unit is in the range of 0.02 to 0.50 moles.

[0029] The linear organosiloxane block Y has a diorganopolysiloxane structure, and R Ｃ is a monovalent organic group, and the functional group R Ａ Examples include monovalent hydrocarbon groups selected from alkyl groups, alkenyl groups, aryl groups, aralkyl groups, and halogenated alkyl groups in which some of the hydrogen atoms have been substituted with halogen atoms such as fluorine atoms, and industrially, it may be a methyl group or a phenyl group. β represents the number of repeating diorganosiloxy units and is a number of 2 or more, and may be a number ranging from 2 to 10,000, 5 to 5,000, 5 to 1,000, 5 to 500, 5 to 250, 10 to 200, or 10 to 150.

[0030] The linking group between the silicon atoms constituting the resinous organosiloxane block X and the linear organosiloxane block Y of component (A1) is not particularly limited, but may be, and is preferably, a resin-linear structure-containing organopolysiloxane block copolymer having a structure in which the silicon atoms are linked by a siloxane bond or a silalkylene bond. These linking groups can be introduced between molecules by a condensation reaction or hydrosilylation reaction of the precursor compounds of block X and block Y. It is particularly preferred that block X and block Y are linked by a siloxane bond between the silicon atoms by a condensation reaction of the precursor compounds of both blocks.

[0031] The block copolymer serving as component (A1) according to the present invention is not particularly limited in terms of its siloxane polymerization degree, but from the standpoint of imparting a coatable viscosity to the curable organopolysiloxane composition containing it, the siloxane polymerization degree is preferably in the range of 10 to 10,000, and more preferably in the range of 25 to 2,000. In particular, when an organopolysiloxane with a high polymerization degree exceeding the above upper limit is used, coating of the curable organopolysiloxane composition may become difficult unless an organic solvent or diluent is used.

[0032] The component (A2) is an organosiloxane mixture obtained by mixing the following components (A2-1) and (A2-2) in a mass ratio of 1:99 to 80:20, and the mass ratio may be 20:80 to 60:40. Here, the component (A2-1) contains the functional group R Ａ M including ＲＡ M including units and alkenyl groups Ａｌｋ Component (A2-2) is a resinous organopolysiloxane having units, and component (A2-2) is a component that provides a linear organopolysiloxane structure through a chain extension reaction.

[0033] The component (A2-1) is R Ａ a R Ｂ （３－ａ） SiO １／２ (R Ａ is a silicon-bonded functional group containing an acrylic or methacrylic group, and R Ｂ is R Ａ and a is a number ranging from 1 to 3). ＲＡ Units), R Ｂ´ ３ SiO １／２ (R Ｂ´ is R Ａ is a monovalent organic group other than Ｂ´ at least one of which is an alkenyl group Ａｌｋ units) and SiO ４／２ The organopolysiloxane is a resinous organopolysiloxane having an acrylic or methacrylic group, which contains siloxane units (Q units) represented by the following formula: Ａ , R Ｂ , R Ｂ´is the same group as above, and a is the same number as above. ＲＡ Unit, M Ａｌｋ units, Q units and optionally M units, ＲＡ Units and M Ａｌｋ The sum of the amounts of substances of the units is in the range of 0.5 to 2.0 moles, and the ratio of M to 1 mole of Q units is ＲＡ The organopolysiloxane resin may have a unit substance amount in the range of 0.02 to 0.50 moles.

[0034] Component (A2-2) is a linear organopolysiloxane having two alkenyl groups in the molecule, and preferably has alkenyl groups only at both ends of the molecular chain. More specifically, dialkylalkenylsiloxy groups, industrially known as (C2-C8 alkenyl)(CH ３ ) ２ SiO １／２ An example is a polydimethylsiloxane terminated with (C2-C8 alkenyl)dimethylsiloxy units represented by the formula: Here, the degree of polymerization of the diorganosiloxane of component (A2-2) is not particularly limited, but from the standpoint of coatability, it may be a number within the range of 2 to 10,000, 5 to 5,000, 5 to 1,000, 5 to 500, 5 to 250, 10 to 200, or 10 to 150. On the other hand, linear organopolysiloxanes having more than two alkenyl groups per molecule result in three-dimensional crosslinking reaction sites rather than two-dimensional intermolecular chain extension reactions, and therefore may not fully achieve the technical effects of the present invention, such as initial adhesive strength.

[0035] The component (A3) is an organosiloxane mixture obtained by mixing the following components (A3-1) to (A3-3). Here, the component (A3-1) contains the functional group R Ａ Contains M ＲＡ The component (A3-2) is a resinous organopolysiloxane having an M Ａｌｋ(A3-1) is a resinous organopolysiloxane having units, and (A3-3) is a component that provides a linear organopolysiloxane structure through a chain extension reaction. The mixing ratio of each component is not particularly limited, but the mass ratio of (A3-1) + (A3-2):(A3-3) is within a range of 1:99 to 80:20, preferably 20:80 to 60:40, and the mass ratio of (A3-1) to (A3-2) may be within a range of 10:90 to 90:10.

[0036] The component (A3-1) is R Ａ a R Ｂ （３－ａ） SiO １／２ (R Ａ is a silicon-bonded functional group containing an acrylic or methacrylic group, and R Ｂ is R Ａ and a is a number ranging from 1 to 3). ＲＡ units) and SiO ４／２ and R is a resinous organosiloxane having an acrylic or methacrylic group, which comprises siloxane units (Q units) represented by the formula: Ａ , R Ｂ is the same group as above, and a is the same number as above. ＲＡ units, Q units and optionally M units, and ＲＡ The sum of the amounts of substances of the units is in the range of 0.5 to 2.0 moles, and the ratio of M to 1 mole of Q units is ＲＡ The organopolysiloxane resin may have a unit substance amount in the range of 0.02 to 0.50 moles.

[0037] The component (A3-2) is R Ｂ´ ３ SiO １／２ (R Ｂ´ is R Ａ is a monovalent organic group other than Ｂ´ at least one of which is an alkenyl group Ａｌｋ units) and SiO ４／２ and R Ｂ´is the same group as above, and a is the same number as above. Ａｌｋ units, Q units and optionally M units, and Ａｌｋ The organopolysiloxane resin may be one in which the sum of the amounts of the units is in the range of 0.5 to 2.0 moles.

[0038] The component (A3-3) is a linear organopolysiloxane containing two alkenyl groups within the molecule, and preferably has alkenyl groups only at both molecular chain terminals. Such components are similar to the components exemplified above for the component (A2-2).

[0039] [Component (B)] Component (B) is a non-reactive or low-reactive siloxane component used in combination with the above-mentioned component (A), and is one of the characteristic features of the present invention. Component (B) acts as an adhesive strength adjuster, including the initial adhesive strength, of the pressure-sensitive adhesive layer obtained by semi-curing the present composition through a heat curing reaction. A pressure-sensitive adhesive layer containing component (B) exhibits high initial adhesive strength, while its adhesive strength to a substrate changes significantly due to a photocuring reaction accompanying irradiation with high-energy rays.

[0040] More specifically, component (B) is a siloxane component that does not contain a carbon-carbon multiple bond in the molecule, and component (A) (its constituent components) and component (D) described below are siloxane components that contain a functional group R Ａ More specifically, component (B) is one or more siloxane components containing no carbon-carbon multiple bonds selected from the following components (B1) to (B3):

[0041] The component (B1) is an MQ-type organopolysiloxane resin that improves the adhesive strength of the cured layer. Specifically, the component (B1) has R ３ SiO １／２ (wherein R each independently represent a monovalent organic group containing no carbon-carbon multiple bonds), and siloxane units (M units) represented by the formula: ４／２The organopolysiloxane resin contains siloxane units (Q units) represented by the formula: wherein the ratio of M units to 1 mole of Q units is in the range of 0.5 to 2.0, and R is exemplified by a monovalent hydrocarbon group selected from alkyl groups, aryl groups, aralkyl groups, and halogenated alkyl groups in which some of the hydrogen atoms have been substituted with halogen atoms such as fluorine atoms, and industrially may be a methyl group or a phenyl group. Furthermore, component (B1) may contain small amounts of hydroxyl groups (silanol groups) or alkoxy groups, and if necessary, the content of these hydrolyzable groups may be reduced by hydrolyzing them with a silylating agent such as trimethylsilane.

[0042] Component (B2) is a linear or branched diorganopolysiloxane containing no carbon-carbon multiple bonds in the molecule and serves to adjust the adhesive strength of the cured layer. This component (B2) may be a linear or branched diorganopolysiloxane having a functional group selected from monovalent hydrocarbon groups selected from hydroxyl groups (silanol groups), alkyl groups, aryl groups, aralkyl groups, and halogenated alkyl groups in which some of the hydrogen atoms have been substituted with halogen atoms such as fluorine atoms. Industrially, this may be exemplified by a linear or branched dimethylpolysiloxane that may contain silanol groups in the molecule. Furthermore, from the standpoint of adjusting the adhesive strength of the cured layer, component (B2) may be a diorganopolysiloxane with a relatively high degree of polymerization, such as a diorganopolysiloxane with a number-average molecular weight of 100,000 or more. This component (B2) may preferably be a gum-like diorganopolysiloxane having a viscosity at room temperature of 1,000,000 mPa·s or more and a plasticity of 1,000,000 mPa·s or more. Here, "having plasticity" means that the plasticity measured in accordance with the method specified in JIS K6249 is measurable (the thickness when a 4.2 g spherical sample is subjected to a load of 1 kgf for 3 minutes at 25°C, is read to the nearest 1 / 100 mm, and this value is multiplied by 100). In particular, component (B2) may be a crude rubber-like polydimethylsiloxane having a plasticity in the range of 50 to 200.

[0043] The (B3) component is a condensation reaction product of the (B1) component and the (B2) component, and is particularly preferred as a component for adjusting the adhesive strength of the cured layer. Such a (B3) component can be obtained by condensing the above-mentioned (B1) or (B2) component, which has a hydrolyzable functional group such as a silanol group in the molecule, using a known method. A condensation reaction product with a relatively high degree of polymerization is preferred, and a condensation reaction product of the above-mentioned (B1) component and the (B2) component, which has a number average molecular weight of 100,000 or more after condensation, is preferred. Note that such a condensation reaction product with a high degree of polymerization and a high molecular weight can be easily obtained by condensing the (B1) component and the (B2) component, which have a relatively high molecular weight, in the presence of a known condensation reaction catalyst.

[0044] The curable organopolysiloxane composition according to the present invention or an organopolysiloxane pressure-sensitive adhesive composition containing the same may contain one or more components selected from the above-mentioned components (B2) and (B3) as at least part or all of component (B). A semi-cured product containing these components can adjust its adhesive strength, and when the semi-cured product is cured by a photocuring reaction involving irradiation with high-energy rays, some of these components bleed out onto the surface of the cured layer, forming a smooth surface, which not only reduces adhesive strength as the curing reaction progresses but also significantly improves releasability from the substrate.

[0045] In the curable organopolysiloxane composition of the present invention, the amount of component (B) used can be appropriately determined taking into consideration the desired initial adhesive strength and the releasability of the cured product after the photocuring reaction, but is typically in the range of 1 to 50 parts by mass, 5 to 40 parts by mass, or 10 to 30 parts by mass per 100 parts by mass of component (A). Furthermore, component (B) preferably contains a combination of component (B1) and one or more selected from component (B2) and component (B3), with the mass ratio of the two being in the range of 50:50 to 95:5. This range provides high initial adhesive strength, a significant reduction in adhesive strength after the photocuring reaction, and improved releasability from the substrate.

[0046] [(C) Photoradical Polymerization Initiator] Component (C) is a photoradical polymerization initiator that, upon irradiation with high-energy rays, converts the silicon atom-bonded functional group (RＡ In particular, it is a component that accelerates the photocuring reaction of the unreacted functional groups (R Ａ By irradiating a pressure-sensitive adhesive layer made of a semi-cured product containing the above-mentioned compound with high-energy rays, the adhesive strength of the pressure-sensitive adhesive layer to the substrate is significantly reduced, and an easily peelable cured product is formed.

[0047] Photoradical polymerization initiators are broadly divided into photocleavage type and hydrogen abstraction type. The photoradical polymerization initiator used in the composition of the present invention can be arbitrarily selected from those known in the art and is not limited to a specific one, but is preferably one that does not inhibit the hydrosilylation reaction at high temperatures of 80°C or higher. Examples of photoradical polymerization initiators include α-ketol compounds such as 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone, α-hydroxy-α,α'-dimethylacetophenone, 2-methyl-2-hydroxypropiophenone, and 1-hydroxycyclohexylphenyl ketone; acetophenone compounds such as methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, and 2-methyl-1-[4-(methylthio)-phenyl]-2-morpholinopropane-1; benzoin ether compounds such as benzoin ethyl ether, benzoin isopropyl ether, and anisoin methyl ether; and ketal compounds such as benzyl dimethyl ketal. aromatic sulfonyl chloride compounds such as 2-naphthalenesulfonyl chloride; photoactive oxime compounds such as 1-phenone-1,1-propanedione-2-(o-ethoxycarbonyl)oxime; benzophenone compounds such as benzophenone, benzoylbenzoic acid, and 3,3'-dimethyl-4-methoxybenzophenone; thioxanthone compounds such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, and 2,4-diisopropylthioxanthone; camphorquinone; halogenated ketones; acylphosphinoxides; and acylphosphonates.

[0048] The amount of component (C) used is determined based on the amount of silicon-bonded functional groups (R Ａ The amount of component (A) can be appropriately designed depending on the content of component (A) and the desired change in adhesive strength and ease of peeling of the cured product triggered by irradiation with high-energy rays. However, an amount of 0.1 to 10 parts by mass per 100 parts by mass of component (A) is preferred, and an amount of 0.5 to 5 parts by mass is particularly preferred.

[0049] [(C') Photosensitizer] Optionally, a (C') photosensitizer can be used in combination with the (C) photoradical polymerization initiator. The use of a sensitizer can increase the photon quantum efficiency of the polymerization reaction, allowing longer wavelength light to be utilized in the polymerization reaction compared to when a photoinitiator alone is used. This is known to be particularly effective when the coating thickness of the composition is relatively thick or when a relatively long wavelength LED light source is used. Known sensitizers include anthracene-based compounds, phenothiazine-based compounds, perylene-based compounds, cyanine-based compounds, merocyanine-based compounds, coumarin-based compounds, benzylidene ketone-based compounds, (thio)xanthene or (thio)xanthone-based compounds, such as isopropylthioxanthone, 2,4-diethylthioxanthone, squarylium-based compounds, (thia)pyrylium-based compounds, and porphyrin-based compounds. However, any photosensitizer can be used in the curable organopolysiloxane composition and pressure-sensitive adhesive composition of the present invention, without limitation. The amount used is arbitrary, but is generally selected so that the mass ratio of component (C') to component (C) is in the range of 0 to 10, and when used, is in the range of 0.01 to 5.

[0050] [(D) Alkenyl Group-Containing MQ-Type Organopolysiloxane Resin] The composition of the present invention can contain (D) an alkenyl group-containing MQ-type organopolysiloxane resin, independently of components (A) to (C). Component (D) is a reactive component in the heat curing reaction and also serves as an optional component for adjusting adhesion to substrates. Depending on the amount of component used, it is possible to adjust the hardness of the semi-cured product after the hydrosilylation reaction and its adhesion to substrates.

[0051] More specifically, the component (D) contains one or more alkenyl groups in the molecule, and (a) R３ SiO １／２ (wherein R each independently represent a monovalent organic group), and (b) siloxane units (M units) represented by SiO ４／２ The organopolysiloxane resin contains siloxane units (Q units) represented by the following formula: The molar ratio of M units to Q units is preferably 0.5 to 2.0. If this molar ratio is less than 0.5, the adhesion of the cured product to the substrate may decrease, while if it is more than 2.0, the cohesive force of the substance that constitutes the adhesive layer decreases.

[0052] In particular, the molar ratio of (a) M units to (b) Q units is preferably in the range of 0.50:1.00 to 1.50:1.00, more preferably 0.55:1.00 to 1.20:1.00, and even more preferably 0.60:1.00 to 1.10:1.00. ２９ It can be easily measured by Si nuclear magnetic resonance.

[0053] The component (D) has the general unit formula: (R ３ SiO １／２ ) ａ (SiO ４／２ ) ｂ (wherein R are each independently a monovalent organic group, a and b are each a positive number, a+b=1, a / b=0.5 to 1.5) is preferred.

[0054] The (D) component may be composed of only (a) M units and (b) Q units, but R ２ SiO ２／２ Units (D units), and / or RSiO ３／２ In the formula, each R independently represents a monovalent organic group. The total content of (a) M units and (b) Q units in component (D) is preferably 50% by mass or more, more preferably 80% by mass or more, and particularly preferably 100% by mass.

[0055] Since component (D) is a reactive MQ-type organopolysiloxane resin that is added independently of component (A), the monovalent organic group (R) is not particularly limited, and may be any of the above-mentioned functional groups R ＡExamples of the R groups include monovalent hydrocarbon groups selected from alkyl, alkenyl, aryl, and aralkyl groups, and halogenated alkyl groups in which some of the hydrogen atoms have been substituted with halogen atoms such as fluorine atoms. Industrially, these groups may be methyl or phenyl. However, at least one of all R groups in the molecule must be an alkenyl group. The alkenyl groups in component (D) may be alkenyl groups having 2 to 8 carbon atoms (C2-C8 alkenyl), more preferably vinyl or hexenyl, and the other R groups may be alkyl groups (especially including methyl) or phenyl. Component (D) may also contain hydrolyzable groups such as hydroxyl or alkoxy groups, and may be an organopolysiloxane resin in which the content of these hydrolyzable groups has been reduced by hydrolyzing these groups with a silylating agent such as trimethylsilane.

[0056] Component (D) is an optional component and can be blended in an amount of 0.0 to 50 parts by mass per 100 parts by mass of component (A), with 0.5 to 35 parts by mass being preferred, and a range of 1.0 to 20 parts by mass being particularly preferred.

[0057] [(E) Organohydrogenpolysiloxane] Component (E) is an organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms in one molecule, and functions as a crosslinker for the curable organopolysiloxane composition. Specifically, it reacts with the alkenyl groups in components (A) and (D) in the presence of the hydrosilylation catalyst (C) to form a pressure-sensitive adhesive layer that is a semi-cured product. This pressure-sensitive adhesive layer has excellent initial adhesive strength to the substrate, while containing unreacted photocurable silicon-bonded functional groups (R Ａ ), the adhesive strength is greatly reduced by the two-stage curing triggered by irradiation with high-energy rays, resulting in easy peelability.

[0058] The molecular structure of component (E) is not particularly limited, and examples include cyclic organohydrogenpolysiloxanes having at least three silicon-bonded hydrogen atoms per molecule, linear, partially branched linear, branched, and resin-like structures. Linear, partially branched linear, and resin-like structures are preferred. The viscosity of component (E) at 25°C is not particularly limited, but is preferably in the range of 1 to 10,000 mPa·s or 1 to 1,000 mPa·s. Furthermore, component (E) may be at least one selected from linear, branched, and resin-like organohydrogenpolysiloxanes having at least three silicon-bonded hydrogen atoms per molecule. Component (E) may also be a mixture of two or more of the above organohydrogenpolysiloxanes.

[0059] The silicon atoms to which the silicon-bonded hydrogen atoms in component (E) are bonded are not limited, and examples include silicon atoms at the molecular chain terminals and / or other silicon atoms. Furthermore, examples of silicon-bonded organic groups in component (E) include monovalent hydrocarbon groups having 1 to 12 carbon atoms and no aliphatic unsaturated bonds, specifically alkyl groups having 1 to 12 carbon atoms such as methyl, ethyl, propyl, butyl, pentyl, hexyl, and octyl; aryl groups having 6 to 12 carbon atoms such as phenyl, tolyl, and xylyl; aralkyl groups having 7 to 12 carbon atoms such as benzyl and phenethyl; and halogen-substituted alkyl groups having 1 to 12 carbon atoms such as 3-chloropropyl and 3,3,3-trifluoropropyl, with methyl and phenyl being preferred.

[0060] Examples of such component (E) include 1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane, tris(dimethylhydrogensiloxy)methylsilane, tris(dimethylhydrogensiloxy)phenylsilane, 1-glycidoxypropyl-1,3,5,7-tetramethylcyclotetrasiloxane, 1,5-glycidoxypropyl-1,3,5,7-tetramethylcyclotetrasiloxane, 1-glycidoxypropyl-5-trimethoxysilylethyl-1,3,5,7-tetramethylcyclotetrasiloxane, methylhydrogenpolysiloxane terminally blocked with trimethylsiloxy groups, and dimethylsiloxane-methylhydrogensiloxane terminally blocked with trimethylsiloxy groups. Examples include silane copolymers, dimethylpolysiloxanes terminally blocked with dimethylhydrogensiloxy groups, dimethylsiloxane-methylhydrogensiloxane copolymers terminally blocked with dimethylhydrogensiloxy groups, methylhydrogensiloxane-diphenylsiloxane copolymers terminally blocked with trimethylsiloxy groups, methylhydrogensiloxane-diphenylsiloxane-dimethylsiloxane copolymers terminally blocked with trimethylsiloxy groups, hydrolysis condensates of trimethoxysilane, copolymers consisting of (CH3)2HSiO1 / 2 units and SiO4 / 2 units, copolymers consisting of (CH3)2HSiO1 / 2 units, SiO4 / 2 units and (C6H5)SiO3 / 2 units, and mixtures of two or more of these.

[0061] Examples of cyclic organohydrogenpolysiloxanes include those represented by the following formula: [(R ３ HSiO ｍ３ (R ３ ２ SiO) ｍ４ Here, m3+m4 is a number ranging from 3 to 20, m3 is a number equal to or greater than 3, and m4 is a number equal to or greater than 0. R ３ is a monovalent hydrocarbon group having 1 to 10 carbon atoms, excluding alkenyl groups, and R ２ Examples include groups similar to those shown below, and preferably a methyl group or a phenyl group.

[0062] The linear or branched organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms in the molecule is an organohydrogenpolysiloxane such as a polyorganohydrogensiloxane or an organohydrogensiloxane-diorganosiloxane copolymer having at least two silicon-bonded hydrogen atoms in the side chain portion and having the molecular chain terminals blocked with trialkylsiloxy groups, aryldialkylsiloxy groups, etc. The degree of polymerization of the siloxane is in the range of 4 to 500, preferably 5 to 200.

[0063] The amount of component (E) used can be selected appropriately depending on the desired adhesive strength and curing characteristics, but from the standpoint of the initial adhesive strength and easy peelability triggered by irradiation with high-energy rays, which are the objectives of the present invention, it is preferably in the range of 0.1 to 5 parts by mass, more preferably 0.5 to 4.5 parts by mass, and particularly preferably 1.0 to 3.5 parts by mass, per 100 parts by mass of component (A). If the amount of component (E) used is less than the lower limit, there may be a shortage of crosslinker, resulting in insufficient heat curing of the composition, while if it exceeds the upper limit, the change in adhesive strength of the adhesive layer before and after irradiation with high-energy rays may be small, making it impossible to achieve the object of the present invention. Preferably, the amount of component (E) used is such that the number of moles of silicon-bonded hydrogen atoms in component (E) relative to the number of moles of aliphatic unsaturated carbon-carbon bonds, such as alkenyl groups, in the composition (hereinafter referred to as the "SiH / Vi ratio") is in the range of 0.1 to 5.0, more preferably 0.1 to 2.0, and even more preferably 0.1 to 0.75. Within this range, the overall crosslink density can be appropriately adjusted, making it possible to exhibit the desired properties in terms of storage modulus and adhesion of the cured product. On the other hand, if the SiH / Vi ratio is below this lower limit, adhesive residue may be left behind when the cured product is adhered to a substrate, while if it exceeds this upper limit, unreacted SiH groups may be excessive, resulting in unstable adhesion properties of the cured product.

[0064] [(F) Hydrosilylation Reaction Catalyst] Component (F) is a hydrosilylation reaction catalyst that, upon heating or other means, promotes the hydrosilylation reaction of component (E) with an aliphatic unsaturated carbon-carbon bond, such as an alkenyl group, in component (A) or any other optional component.

[0065] Examples of hydrosilylation catalysts include platinum catalysts, rhodium catalysts, and palladium catalysts, with platinum catalysts being preferred because they significantly accelerate the curing of the composition, and platinum-alkenylsiloxane complexes being particularly preferred. Examples of alkenylsiloxanes include 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, alkenylsiloxanes in which a portion of the methyl groups of these alkenylsiloxanes have been substituted with groups selected from the group consisting of nitriles, amides, dioxolanes, and sulfolanes, ethyl groups, phenyl groups, etc., and alkenylsiloxanes in which the vinyl groups of these alkenylsiloxanes have been substituted with allyl groups, hexenyl groups, etc. In particular, 1,3-divinyl-1,1,3,3-tetramethyldisiloxane is preferred due to the favorable stability of this platinum-alkenylsiloxane complex, and it is preferable to add it in the form of an alkenylsiloxane solution. Additionally, from the standpoint of improving handling and the pot life of the composition, these hydrosilylation catalysts may be hydrosilylation catalyst-containing thermoplastic resin microparticles, particularly thermoplastic resin microparticles containing a platinum-containing hydrosilylation catalyst, which are catalysts dispersed or encapsulated in a thermoplastic resin such as a silicone resin, a polycarbonate resin, or an acrylic resin. Non-platinum metal catalysts such as iron, ruthenium, or iron / cobalt may also be used as catalysts that promote the hydrosilylation reaction.

[0066] In the present invention, the content of the hydrosilylation catalyst is not particularly limited, but is preferably in a range such that the platinum-based metal content is 0.1 to 200 ppm, 0.1 to 150 ppm, 0.1 to 100 ppm, or even 0.1 to 50 ppm relative to the total solids content of the composition. Here, the platinum-based metal refers to a Group VIII metal element consisting of platinum, rhodium, palladium, ruthenium, and iridium. From a practical perspective, it is preferable that the platinum metal content, excluding the ligands of the hydrosilylation catalyst, be within the above range. The solids content refers to the components (mainly the base resin, adhesion-imparting component, crosslinking agent, catalyst, and other non-volatile components) that form a cured layer when the curable organopolysiloxane composition of the present invention is cured, but does not include volatile components such as solvents that volatilize during heat curing.

[0067] When the content of platinum-based metal in the curable organopolysiloxane composition of the present invention is 50 ppm or less (45 ppm or less, 35 ppm or less, 30 ppm or less, 25 ppm or less, or 20 ppm or less), discoloration or coloration of the transparent adhesive layer may be particularly suppressed after curing or when exposed to high-energy rays such as heat or ultraviolet light. On the other hand, from the viewpoint of the curability of the organopolysiloxane composition, the content of platinum-based metal should be 0.1 ppm or more, and a content below this lower limit may cause poor curing.

[0068] [(G) Cure Retarder] The curable organopolysiloxane composition of the present invention may optionally contain a cure retarder. The cure retarder is incorporated to inhibit the crosslinking reaction between the aliphatic unsaturated carbon-carbon bond-containing groups and silicon-bonded hydrogen atoms in the composition, thereby extending the usable time at room temperature and improving storage stability. Therefore, in practice, it is a nearly essential component for the curable organopolysiloxane composition of the present invention.

[0069] Specific examples of the cure retarder include acetylene compounds, enyne compounds, organic nitrogen compounds, organic phosphorus compounds, oxime compounds, and phosphorus compounds. Specific examples include alkyne alcohols such as 3-methyl-1-butyn-3-ol, 3,5-dimethyl-1-hexyn-3-ol, 3-methyl-1-pentyn-3-ol, 1-ethynyl-1-cyclohexanol, and phenylbutynol; enyne compounds such as 3-methyl-3-penten-1-yne and 3,5-dimethyl-1-hexyn-3-yne; methylalkenylcyclosiloxanes such as 2-ethynyl-4-methyl-2-pentene, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, and 1,3,5,7-tetramethyl-1,3,5,7-tetrahexenylcyclotetrasiloxane; and benzotriazole.

[0070] The phosphorus-containing hydrosilylation reaction retarder may be at least one selected from the group consisting of phosphine compounds, phosphoric acid compounds, phosphonic acid compounds, phosphine oxide compounds, phosphorous acid compounds, and phosphonous acid compounds, and examples thereof include the components described in JP-A-2007-308542, such as 1,3-bis(diphenylphosphino)propane.

[0071] From the standpoint of the curing behavior of the composition, it is preferable that the curable organopolysiloxane composition of the present invention exhibits a viscosity increase of no more than 1.5 times after 8 hours at room temperature following preparation of the composition, and be curable at 80 to 200°C. Suppressed viscosity increase is important from the standpoints of handling, pot life, and post-cured properties, and curing at a high temperature (80 to 200°C) or higher can ensure curability. Such a composition can be achieved by selecting an appropriate combination and blending amounts of the above-mentioned components, hydrosilylation catalyst, and cure retarder.

[0072] [(H) Release Modifier] In addition to the components (A) to (G) (particularly component (B2)), any release modifier may be added to the composition of the present invention. The use of this component makes it possible to adjust the viscosity required for coating the curable organopolysiloxane composition, as well as the tackiness, hardness, crosslink density, etc. of the cured or semi-cured product, and may also improve the release properties, etc. of the cured product.

[0073] Such release modifiers are not particularly limited in type or amount, as long as they have a certain degree of compatibility with the other components and are capable of improving the release properties of the cured product. Known release modifiers selected from fluorosilicones having perfluoroalkyl groups or the like, MQ-type silicone resins which may optionally have lower or higher alkenyl groups, α,ω-diolefin compounds, medium to long chain olefin compounds having an alkenyl group at only one end, linear organopolysiloxanes which may optionally have an alkenyl group, or mixtures thereof may be added within the required range of release force adjustment.

[0074] For example, in the present invention, a linear organopolysiloxane that may optionally contain alkenyl groups can be added as a release modifier, independently of component (B2), etc. Specific examples of such release modifiers include polydimethylsiloxanes, polyphenylmethylsiloxanes, poly(dimethylsiloxane-diphenylsiloxane) copolymers, poly(dimethylsiloxane-trifluoropropylmethylsiloxane) copolymers, and poly(dimethylsiloxane-nonafluorohexylmethylsiloxane) copolymers, which have a viscosity at 25°C in the range of 1.5 to 1,000,000 mPa·s and are end-blocked with trimethylsiloxy or vinyldimethylsiloxy groups, but as noted above, the release modifier is not limited to these components.

[0075] [(I) Organic Solvent] The composition according to the present invention can be designed as a low-solvent or solvent-free composition by selecting components having a relatively low viscosity, but may optionally contain an organic solvent (I). The organic solvent may be used as a diluent for dispersing or dissolving each component in order to improve the coatability or wettability of the composition to a substrate, or may be a component inevitably contained as a solvent accompanying other raw material components.

[0076] The organic solvent that can be used in the present invention is not particularly limited in type as long as it is a compound that can dissolve all or some of the constituent components in the composition, as long as the technical effects of the present invention are not impaired, and preferably has a boiling point of 80° C. or higher and 200° C. or lower. The type may be a non-halogenated solvent or a halogenated solvent, and examples include aromatic hydrocarbon solvents, aliphatic hydrocarbon solvents, ester solvents, alcohol solvents, ether solvents, chlorinated aliphatic hydrocarbon solvents, and volatile oil solvents, and two or more types may be combined depending on the coatability, wettability, etc.

[0077] The content of the organic solvent is preferably from 0 to less than 60% by mass, more preferably less than 50% by mass, and even more preferably substantially from 0 to 30% by mass, relative to 100 parts by mass of the total composition. In particular, the composition of the present invention can be easily designed so that the solid content concentration that forms the solid content through the curing reaction is in the range of 30 to 100% by mass of the total composition.

[0078] [Other Optional Components] The curable organopolysiloxane composition of the present invention may optionally contain components other than those described above, provided that the technical effects of the present invention are not impaired. For example, the curable organopolysiloxane composition may contain an adhesion promoter; a non-reactive organopolysiloxane other than component (B), such as polydimethyldiphenylsiloxane; an antioxidant such as a phenol, quinone, amine, phosphorus, phosphite, sulfur, or thioether; a light stabilizer such as a triazole or benzophenone; a flame retardant such as a phosphate ester, halogen, phosphorus, or antimony; or one or more antistatic agents such as a cationic surfactant, anionic surfactant, or nonionic surfactant. In addition to these components, pigments, dyes, inorganic fine particles (reinforcing fillers, dielectric fillers, conductive fillers, thermally conductive fillers), etc. may also be optionally blended.

[0079] The method for preparing the curable organopolysiloxane composition of the present invention is not particularly limited, and can be carried out by homogeneously mixing the respective components. An organic solvent may be added as needed, and the composition may be prepared by mixing using a known stirrer or kneader. Since the composition exhibits hydrosilylation reactivity upon heating, it is preferable to mix the components at a temperature below 100°C, preferably below 50°C.

[0080] [Method of Use as an Adhesive] Because the curable organopolysiloxane composition of the present invention contains the above-mentioned component (A), it has both heat-curing properties and photo-curing properties when irradiated with high-energy rays. In particular, the semi-cured product obtained by heat curing functions as an adhesive layer with excellent initial adhesive strength, and by irradiating this with high-energy rays, the adhesive strength of the adhesive layer to the substrate is greatly reduced, forming an easily peelable cured product that can be easily removed from the substrate. The method of use is described below.

[0081] [Coating and Heat Curing] The curable organopolysiloxane composition of the present invention is coated onto a substrate to form a coating film, and when heated at a temperature of 80 to 200°C, preferably 90 to 150°C, a hydrosilylation reaction occurs to give a semi-cured product that functions as a pressure-sensitive adhesive layer with excellent initial adhesive strength. The heating time required for curing can be selected appropriately depending on the thickness of the pressure-sensitive adhesive layer and the amount of catalyst used, but is generally in the range of 0.5 to 90 minutes. The pressure-sensitive adhesive layer obtained by heat curing using the composition of the present invention contains unreacted silicon-bonded functional groups (R Ａ ), it maintains further photocuring reactivity triggered by irradiation with high-energy rays.

[0082] Examples of coating methods include gravure coating, offset coating, offset gravure, roll coating, reverse roll coating, air knife coating, curtain coating, and comma coating. The amount of coating can be designed to a desired thickness depending on the application such as a display device, and the thickness of the pressure-sensitive adhesive layer after curing is, for example, 1 to 1,000 μm, or may be 5 to 900 μm, or may be 10 to 800 μm, but is not limited to these.

[0083] The semi-cured product prior to the photocuring reaction has sufficient initial adhesive strength, and for example, when a 75 μm thick adhesive layer is designed, it is possible to design an adhesive layer having an adhesive strength of 30 gf / 25 mm or more, preferably in the range of 30 to 2000 gf / 25 mm, measured against a stainless steel plate at a tensile speed of 300 mm / min using the 180° peel test method according to JIS Z 0237. Note that the above thickness (75 μm) is the thickness of the cured layer itself, which serves as a standard for objectively defining the adhesive strength of the cured layer according to the present invention, and it goes without saying that the curable organopolysiloxane composition of the present invention can be used as a cured layer or adhesive layer of any thickness, not limited to 75 μm.

[0084] [Change in adhesive strength due to irradiation with high-energy rays] The adhesive layer, which is a semi-cured product obtained by heat curing, undergoes a further photocuring reaction triggered by irradiation with high-energy rays, resulting in a significant decrease in adhesive strength, forming a hard cured product that is easily peelable and does not leave any adhesive residue on the substrate, etc., and can be easily peeled off from the substrate. Specifically, when the organopolysiloxane semi-cured product obtained by the heat curing reaction is adhered to another substrate, the adhesive strength to the substrate decreases by 10% or more before and after the photocuring reaction associated with irradiation with high-energy rays, preferably by 30% or more, and particularly preferably by 50% or more. Note that such changes in adhesive strength can be quantitatively measured by the adhesive strength measurement test using the above-mentioned SUS plate, etc.

[0085] In particular, the present invention has the distinct advantage that it achieves the above-mentioned strong initial adhesive strength by using the above-mentioned component (A) and component (B) (preferably a combination of component (B1) and either component (B2) or (B3)), and can be designed so that the adhesive strength to the substrate decreases in the range of 30 to 99% before and after the photocuring reaction triggered by irradiation with high-energy rays, and that it can achieve easy peelability from the substrate after the photocuring reaction.

[0086] Examples of high-energy rays (also called active energy rays) used in the photocuring reaction include ultraviolet rays, electron beams, and radiation, with ultraviolet rays being preferred from the viewpoint of practicality. Suitable ultraviolet light sources include high-pressure mercury lamps, medium-pressure mercury lamps, Xe—Hg lamps, and deep UV lamps. In particular, ultraviolet radiation with a wavelength of 280 to 400 nm, preferably 300 to 400 nm, is preferred, and a light source having multiple emission bands may also be used.

[0087] The amount of high-energy radiation can be appropriately designed, but the ultraviolet radiation amount (illuminance) is preferably 100 mJ / cm as the cumulative light amount. ２ ~10,000mJ / cm ２ , more preferably 1,000 mJ / cm ２ ~5,000mJ / cm ２When the high-energy ray irradiation is performed, a favorable change in adhesive strength of the adhesive layer according to the present invention is realized, triggered by the irradiation of the high-energy ray. Note that the high-energy ray irradiation may be performed through a substrate supporting the adhesive layer according to the present invention, as long as the substrate does not absorb electromagnetic waves in the above wavelength range. In other words, as long as a certain amount of irradiation can be achieved, the high-energy ray irradiation may be performed through a substrate or a cover material such as a protective film.

[0088] [Transparency, Color Tone, or Coloring / Discoloration Properties of the Pressure-Sensitive Adhesive Layer] The pressure-sensitive adhesive layer (including semi-cured and cured products) obtained by curing the curable organopolysiloxane composition and organopolysiloxane pressure-sensitive adhesive composition according to the present invention may be substantially transparent, translucent, or opaque, and its transparency can be designed depending on the application of the pressure-sensitive adhesive layer. When the pressure-sensitive adhesive layer is visually transparent, more objectively, the transmittance of light at a wavelength of 450 nm through a 100 μm-thick cured layer is 80% or more, preferably 90% or more, and may be designed to be 95% or more, assuming that the transmittance through air is 100%. On the other hand, for pressure-sensitive adhesives such as temporary fixation where light transmittance is not required, the pressure-sensitive adhesive layer may be translucent to opaque, and filler components or additives that impair colorability or light transmittance may be used depending on the required properties other than light transmittance.

[0089] [Method of use as a pressure-sensitive adhesive layer, pressure-sensitive adhesive sheet with change in adhesive properties before and after irradiation with high-energy rays] In order to improve the adhesion of the pressure-sensitive adhesive layer according to the present invention to an adherend, the surface of the pressure-sensitive adhesive layer or substrate may be subjected to surface treatment such as primer treatment, corona treatment, etching treatment, plasma treatment, etc. However, since the adhesion layer of the present invention has excellent adhesion to substrates such as display devices as described above, these steps may be added as necessary to further improve the adhesion to the adherend, and higher production efficiency may be achieved by omitting these steps.

[0090] The curable organopolysiloxane composition according to the present invention can be applied to a release liner and then semi-cured by a condensation reaction by heating under the above-mentioned temperature conditions, and the release liner can be peeled off and the composition can be attached to a film-like substrate, tape-like substrate, or sheet-like substrate (hereinafter referred to as "film-like substrate"). Alternatively, the curable organopolysiloxane composition can be applied to a film-like substrate and then cured by heating under the above-mentioned temperature conditions to form a pressure-sensitive adhesive layer on the surface of the substrate. As described above, this pressure-sensitive adhesive layer has excellent initial adhesion, and because it contains photocurable functional groups derived from component (A), its adhesive strength decreases and its adhesive properties change to easy peelability when exposed to high-energy rays.

[0091] A laminate having a cured layer, particularly a film-like cured layer, formed by curing the organopolysiloxane composition of the present invention on such a film-like substrate may be used for adhesive tapes, detachable protective films, adhesive bandages, low-temperature supports, transfer films, labels, emblems, and decorative or explanatory signs. Furthermore, a cured layer formed by curing the organopolysiloxane composition of the present invention may be used in the assembly of automobile parts, toys, electronic circuits, or keyboards. Alternatively, a cured layer formed by curing the organopolysiloxane composition of the present invention, particularly a film-like adhesive layer, may be used for the protection, construction, and use of laminated touch screens or flat panel displays.

[0092] Examples of substrates include paperboard, corrugated cardboard, clay-coated paper, polyolefin-laminated paper, particularly polyethylene-laminated paper, synthetic resin film / sheet, natural fiber cloth, synthetic fiber cloth, artificial leather cloth, and metal foil. Synthetic resin film / sheet is particularly preferred, and examples of synthetic resins include polyimide, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polycarbonate, polyethylene terephthalate, cyclopolyolefin, and nylon. When heat resistance is particularly required, films of heat-resistant synthetic resins such as polyimide, polyether ether ketone, polyethylene naphthalate (PEN), liquid crystal polyarylate, polyamide imide, and polyether sulfone are preferred. On the other hand, for applications requiring visibility, such as display devices, transparent substrates, specifically transparent materials such as polypropylene, polystyrene, polyvinylidene chloride, polycarbonate, polyethylene terephthalate, and PEN are preferred.

[0093] The substrate is preferably in the form of a film or sheet. There are no particular limitations on its thickness, and it can be designed to a desired thickness depending on the application. Furthermore, in order to improve the adhesion between the support film and the cured adhesive layer, a support film that has been subjected to a primer treatment, a corona treatment, an etching treatment, or a plasma treatment may be used. In addition, the surface of the film substrate opposite the cured layer / cured adhesive layer may be subjected to a surface treatment such as scratch prevention, stain prevention, fingerprint prevention, anti-glare, anti-reflection, or anti-static treatment.

[0094] The pressure-sensitive adhesive layer according to the present invention may be a single layer or a multilayer consisting of two or more laminated pressure-sensitive adhesive layers, depending on the required properties. A multilayer pressure-sensitive adhesive layer may be formed by laminating films prepared one by one, or by carrying out the process of applying a curable silicone composition to a film substrate equipped with a release layer and then curing the composition multiple times.

[0095] The pressure-sensitive adhesive layer according to the present invention may be given the role of bonding or adhering between members, as well as serving as another functional layer selected from a dielectric layer, a conductive layer, a heat dissipation layer, an insulating layer, a reinforcing layer, etc. In particular, the pressure-sensitive adhesive layer according to the present invention, which is a semi-cured product obtained by heat-curing the curable organopolysiloxane, has excellent initial adhesiveness, and because it contains a photocurable functional group derived from component (A), its adhesive strength decreases and its adhesive properties change to easy peelability when triggered by high-energy ray irradiation. Therefore, after fixing or bonding is performed using a desired device or process, a cured adhesive layer is formed that can be very easily removed from the surface of the substrate by high-energy ray irradiation, and therefore it is extremely useful for temporary functional layers or for temporary fixing of functional layers that are intended to be attached or detached.

[0096] When the pressure-sensitive adhesive layer obtained by heat-curing the curable organopolysiloxane composition of the present invention is a pressure-sensitive adhesive sheet whose adhesive properties change before and after irradiation with high-energy radiation, the pressure-sensitive adhesive layer is preferably handled as a laminate film releasably adhered to a film substrate provided with a release layer having release coating properties. The release layer is also called a release liner, separator, release layer, or release coating layer, and is preferably a release layer having release coating properties such as a silicone-based release agent, a fluorine-based release agent, an alkyd-based release agent, or a fluorosilicone-based release agent, or the substrate itself may form physical fine irregularities on the substrate surface or may be difficult to adhere to the adhesion layer of the present invention. In particular, in the laminate of the present invention, it is preferable to use a release layer obtained by curing a fluorosilicone-based release agent as the release layer.

[0097] The pressure-sensitive adhesive layer according to the present invention has the characteristic adhesive properties described above and can achieve transparency and low haze. Therefore, it is useful as an elastic adhesion layer or temporary fixing layer for components of various electronic devices or electrical devices, and as a protective film during semiconductor wafer processing. It is also useful as an electronic material, a display device component, or a transducer component (including sensors, speakers, actuators, and generators), and the cured product is preferably used as a component for electronic components or display devices. The cured product according to the present invention may be transparent or opaque. However, a film-shaped cured product, particularly a substantially transparent protective film, is suitable as a component for a display panel or display, and is particularly useful for so-called touch panel applications in which devices, particularly electronic devices, can be operated by touching the screen with a fingertip or the like. The cured product layer according to the present invention may also be used as a film- or sheet-like component for sensors, speakers, actuators, etc., where transparency is not required and a certain degree of stretchability or flexibility is required for the adhesion layer itself.

[0098] [Use as an Adhesion Tape] An article comprising a cured layer obtained by curing the curable organopolysiloxane composition of the present invention may be an adhesion tape, particularly a protective tape intended to be attached and detached, characterized in that it comprises the above-mentioned adhesion layer and a sheet-like member made of a textile product such as the above-mentioned synthetic resin film / sheet, metal foil, woven fabric, nonwoven fabric, paper, etc. The type of such adhesion tape is not particularly limited, and examples include insulating tape, heat-resistant tape, solder masking tape, mica tape binder, temporary fixing tape (particularly including temporary fixing tape for silicone rubber parts, etc.), and splicing tape (particularly including splicing tape for silicone release paper).

[0099] In particular, the cured product obtained by curing the curable organopolysiloxane composition of the present invention, particularly the cured product layer, achieves a strong initial adhesive strength of 30 gf / 25 mm or more as measured by a predetermined method, and because it contains a photocurable functional group derived from component (A), its adhesive strength to the substrate decreases by 30 to 99% when triggered by high-energy ray irradiation and its adhesive properties change to easy peelability, allowing for relatively strong adhesion between the adhesive layer used for temporary fixing and the substrate, and also has a stable appearance. After use, it can be easily removed from the substrate surface by irradiation with light such as ultraviolet light, making it particularly suitable for use in functional films that are temporarily used on the assumption that they will be attached and detached, for example, in display devices, semiconductors, etc. In particular, it is extremely useful as a temporary fixing adhesive used in the manufacture of display devices such as CRT displays, liquid crystal displays, plasma displays, organic EL displays, inorganic EL displays, LED displays, surface electrolytic displays (SEDs), and field emission displays (FEDs), as well as touch panels using these devices, as described below.

[0100] [Laminate and Adhesive Sheet] A laminate having a cured adhesive layer formed by curing the curable silicone composition may be formed on the film-like substrate. Preferably, the film-like substrate may be provided with a release layer for the cured adhesive layer.

[0101] In the laminate, the sheet-like substrate preferably has at least one release layer, and the release layer is in contact with the cured adhesive layer. This allows the cured adhesive layer to be easily peeled off from the sheet-like substrate. The release agent contained in the release layer is not particularly limited, and examples thereof include the same release agents as those described above.

[0102] In particular, the laminate may be capable of handling the adhesive layer separated from the film substrate alone, or may have two film substrates. Specifically, the laminate may comprise: a film substrate, a first release layer formed on the film substrate, a pressure-sensitive adhesive layer formed by applying the curable organopolysiloxane composition described above on the release layer and heat-curing it, and a second release layer laminated on the adhesive layer.

[0103] Similarly, the laminate of the above form may be formed, for example, by applying the curable organopolysiloxane composition to one release layer formed on a film-like substrate and curing the composition to form an adhesive layer, and then laminating another release layer on the adhesive layer.

[0104] Alternatively, a laminate of the above form may be produced, for example, by sandwiching the curable silicone composition between a first film-like substrate and a second film-like substrate, forming the composition to a certain thickness with a press or roll while heating, and then curing the composition.

[0105] The first sheet substrate may have a first release layer, or the first sheet substrate itself may have release properties. Similarly, the second sheet substrate may have a second release layer, or the second sheet substrate itself may have release properties. When the first sheet substrate and / or the second sheet substrate have a first release layer and / or a second release layer, it is preferred that the cured adhesive layer contacts the first release layer and / or the second release layer.

[0106] Examples of sheet substrates having release properties include sheet substrates made of materials having release properties such as fluororesin films, and sheet substrates made of materials with no or low release properties such as polyolefin films to which release agents such as silicone, fluororesin, etc. On the other hand, examples of sheet substrates having a release layer include polyolefin films coated with release agents such as silicone, fluororesin, etc.

[0107] The laminate can be used, for example, by applying the cured adhesive layer to an adherend and then peeling the adhesive layer from the film-like substrate.

[0108] The thickness of the adhesive layer (pressure-sensitive adhesive layer) obtained by heat-curing the curable organopolysiloxane composition according to the present invention is preferably 5 to 10,000 μm, and more preferably 10 μm or more or 8,000 μm or less, and even more preferably 20 μm or more or 5,000 μm or less.

[0109] [Display Panel or Display Member] The adhesion layer (pressure-sensitive adhesive layer) obtained by heat-curing the curable organopolysiloxane composition of the present invention can be used for protecting, constructing, and using a laminated touch screen or flat panel display, and its specific method of use can be any known method for using an adhesion layer (for example, a silicone PSA, a silicone adhesive, or a silicone sealant) without any particular limitation.

[0110] The uses of the curable organopolysiloxane composition of the present invention and the pressure-sensitive adhesive layer obtained by semi-curing / curing the composition are not limited to those disclosed above, and films comprising the cured product obtained by curing the composition can be used in various display devices for displaying characters, symbols, and images. The surface shape of such display devices may be curved or curved, rather than flat. Examples include various flat panel displays (FPDs), as well as curved displays or curved transmission screens used in automobiles (including electric vehicles) and aircraft. Furthermore, these display devices may be equipped with a touch panel function that allows input operations by touching icons, notification displays, and operation buttons for executing functions or programs on the screen or display. The device can be applied to display devices such as CRT displays, liquid crystal displays, plasma displays, organic electroluminescent displays, inorganic electroluminescent displays, LED displays, surface electrolytic displays (SEDs), and field emission displays (FEDs), as well as touch panels using these displays. Furthermore, the cured product obtained by curing the composition has excellent adhesion to substrates and viscoelastic properties, and can therefore be used as film or sheet-like members that are transducer members (including those for sensors, speakers, actuators, and generators) such as membranes for speakers, and can also be used as sealing layers or adhesion layers for secondary batteries, fuel cells, or solar cell modules.

[0111] The present invention will be explained in more detail below using examples and comparative examples, but the present invention is not limited to these examples. Furthermore, due to the nature of the semi-cured product of the present invention, high-energy radiation was not irradiated simultaneously during heat curing. (Measurement of Molecular Weight of Organopolysiloxane Component) Using a Waters gel permeation chromatography (GPC) and tetrahydrofuran (toluene) as a solvent, the weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the organopolysiloxane component of the organopolysiloxane resin, etc., were determined in terms of standard polystyrene.

[0112] (Synthesis Example 1) A 1000 mL four-neck flask was charged with the following average formula: (Me ３ SiO １／２ ) ０.４1１ (Me ２ ViSiO １／２ ) ０.０６ (SiO ２ ) ０.４６ (SiO(OH)) ０．０７ 333.0 g of a 60% xylene solution of MQ resin represented by the formula (vinyl group content: 2% by mass, OH group content: 1.7% by mass, hereinafter referred to as Vi-MQ resin), 200.0 g of a polydimethylsiloxane capped with silanol groups at both ends and having a viscosity of 13 Pa·s, and 133.0 g of toluene were added and mixed. 5 g of 30% aqueous ammonia was added to the resulting mixture and stirred at 40°C for 8 hours, after which the ammonia and water were distilled off by refluxing the toluene at 120°C. A compound having an average structure represented by the formula: (Me ３ SiO １／２ ) ０.２０ (Me ２ ViSiO １／２ ) ０.０３ (Me ２ SiO) ０.５０ (SiO ２ ) ０.２４ (SiO(OH)) ０．０３ As a result, 666 g of a resin-linear structure-containing organopolysiloxane block copolymer solution represented by the formula:

[0113] Synthesis Example 2 666.0 g of the condensation mixture obtained in Synthesis Example 1, 26.3 g of 3-(1,1,3,3-tetramethyldisiloxanyl)propyl methacrylate, and 0.1 g of 4-methoxyphenol were added to a 1000 mL four-neck flask and mixed. To this mixture was added 2 ppm, calculated as platinum mass, of a toluene solution of platinum / 1,3-divinyltetramethyldisiloxane complex, and the mixture was stirred for 4 hours while adjusting the temperature to 40°C to 50°C. After confirming the consumption of SiH by IR spectroscopy, the reaction mixture was cooled and stirring was stopped. A compound having an average structure of the following formula: (Me ３ SiO １／２ ) ０.２０６ (Me ２ ViSiO １／２ ) ０.０１３ (Me ２ R Ａ SiO １／２ ) ０.０１７ (Me ２ SiO) ０.５０ (SiO ２ ) ０.２４ (SiO(OH)) ０．０３ As a result, 692 g of a solution of a resin-linear structure-containing organopolysiloxane block copolymer having methacrylic functional groups represented by the formula:

[0114] (Examples 1 to 7, Comparative Examples 1 and 2) Examples and comparative examples of the present invention are described below.

[0115] (Preparation of Curable Silicone Compositions) Using the components shown in Table 1, adhesive compositions made from the curable organopolysiloxane compositions shown in each Example and Comparative Example were prepared as 70% toluene solutions. Note that all percentages in the table are by mass. The viscosity and plasticity of each component were measured at 25°C, and the ratio of the number of silicon-bonded hydrogen atoms to the sum of alkenyl groups in the composition is shown in the table as SiH / Vi. (a1) Resin-linear structure-containing organopolysiloxane shown in Synthesis Example (2) (vinyl group content: 0.48 mass%, methacrylate group content: 1.86 mass%) (a2-1) Me ３ SiO １／２ Siloxane units (M units) represented by ViMe ２ SiO１／２ The siloxane unit (M Ｖｉ Units), R Ａ Me ２ SiO １／２ The siloxane unit (M ＲＡ Unit: R Ａ is the monovalent substituent described in Synthesis Example 1) and SiO ４／２ The weight average molecular weight (Mw) measured by GPC using toluene as a solvent is 78,000 g / mol, and the average composition is M ０．４１ M Ｖｉ ０．０１ M ＲＡ ０．０５ Q ０．５３ (a2-2) a dimethylsiloxane polymer (vinyl group content: 0.10% by mass) capped at both ends with dimethylvinylsiloxy groups and having a viscosity of 37 Pa s; (a') a resin-linear structure-containing organopolysiloxane (vinyl group content: 1.14% by mass) shown in Synthesis Example (1); (b1) a resin having a linear structure containing Me in the molecule; ３ SiO １／２ Siloxane units (M units) represented by the formula: and SiO ４／２ (b1) an organopolysiloxane resin containing siloxane units (Q units) represented by the formula (a) in a molar ratio of 1.0:1.0 (weight average molecular weight (Mw) measured by GPC using toluene as a solvent is 7,000); (b2) a polydimethylsiloxane raw rubber having a plasticity of 170; (b3) a condensation reaction product of the component (b1) and the component (b2) in a mass ratio of 60:40; (c) 2,2-dimethoxy-2-phenylacetophenone (manufactured by Tokyo Chemical Industry Co., Ltd.); (d) an organopolysiloxane resin containing Me in the molecule; ３ SiO １／２ Siloxane units (M units) represented by ViMe ２ SiO １／２ The siloxane unit (M Ｖｉ units), and SiO ４／２(e) a dimethylsiloxy-methylhydrogensiloxy copolymer having a viscosity of 5.2 mPa·s and capped at both ends with trimethylsiloxy groups (hydrogen group content of SiH groups: 0.75% by mass); (f) a solution of a platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex in a dimethylsiloxane polymer having a vinyldimethylsiloxy group capped at both ends with platinum (platinum concentration: approximately 0.7% by mass); and (g) 1-ethynyl-1-cyclohexanol (manufactured by Tokyo Chemical Industry Co., Ltd.).

[0116] (Initial Adhesion Strength Measurement and After UV Irradiation) Each composition was applied to a PET film (manufactured by Toray Industries, Inc., product name: Lumirror (registered trademark) S10, thickness: 50 μm) so that the thickness after curing was 20 μm, and the film was cured at 130°C for 3 minutes. After leaving the film for 30 minutes, the sample was cut to a width of 25 mm, and the adhesive layer surface was attached to a SUS plate (manufactured by Partec) using a roller to prepare a test piece. The adhesive strength (gf / 25 mm) measured against the SUS plate using the 180° peel test method according to JIS Z 0237 at a pulling rate of 300 mm / min is shown in Table 1 as "initial adhesive strength." The test piece was also exposed to UV irradiation (illuminance) of 2,000 mJ / cm2 as an integrated light dose from the PET side using a UV-LED ultraviolet irradiation device (manufactured by JATEC Corporation). ２ The adhesive strength (gf / 25 mm) of the test piece after ultraviolet irradiation was measured in the same manner as above, and is shown in Table 1 as the "adhesive strength after ultraviolet irradiation." *The adhesive strength did not decrease, but increased when exposed to UV light.

[0117] As shown in Table 1, the heat-cured products (semi-cured products) of the curable organopolysiloxane compositions of the present invention according to Examples 1 to 7 had initial adhesive strengths of 30 gf / 25 mm or more, enabling strong temporary fixation and adhesion between substrates. Furthermore, the adhesive layer underwent a significant decrease in adhesive strength upon exposure to ultraviolet light, changing its adhesive properties to easily peelable, while maintaining its transparency. Therefore, when used in the manufacturing processes of semiconductor wafers, display devices, electronic devices, etc., it is expected to be highly useful as a protective film, temporary fixation film, etc.

[0118] On the other hand, in Comparative Example 1, which did not contain the (B) component, sufficient initial adhesive strength was not achieved, and easy peelability was also not achieved. In Comparative Example 2, which did not contain the (A) component, the adhesive strength increased significantly upon exposure to ultraviolet light, and easy peelability was not achieved at all.

Claims

1. (A) 100 parts by mass of one or more (meth)acrylic group-containing organosiloxane components selected from the following components (A1) to (A3): (A1): R Ａ a R Ｂ （３－ａ） SiO １／２ (R Ａ is a silicon-bonded functional group containing an acrylic or methacrylic group, and R Ｂ is R Ａ and a is a number ranging from 1 to 3). ＲＡ Units), R Ｂ´ ３ SiO １／２ (R Ｂ´ is R Ａ is a monovalent organic group other than R Ｂ´ at least one of which is an alkenyl group Ａｌｋ units) and SiO ４／２ and a resinous organosiloxane block X having an acrylic or methacrylic group, which comprises siloxane units (Q units) represented by the formula {R Ｃ ２ SiO ２ / ２ } β (R Ｃ is a monovalent organic group, and β is a number of 2 or more), and a linear organosiloxane block Y having a siloxane unit represented by the formula (I), and the linear organosiloxane block Y has at least one alkenyl group in the molecule. (A2): An organosiloxane mixture obtained by mixing the following components (A2-1) and (A2-2) in a mass ratio of 1:99 to 80:20: (A2-1)R Ａ a R Ｂ （３－ａ） SiO １／２ (R Ａ is a silicon-bonded functional group containing an acrylic or methacrylic group, and R Ｂ is R Ａ and a is a number ranging from 1 to 3). ＲＡ Units), R Ｂ´ ３ SiO １／２ (R Ｂ´ is R Ａ is a monovalent organic group other than R Ｂ´ at least one of which is an alkenyl group Ａｌｋ units) and SiO ４／２ Resinous organopolysiloxanes having acrylic or methacrylic groups, containing siloxane units (Q units) represented by the formula: (A2-2) Linear organopolysiloxane having two alkenyl groups in the molecule (A3): An organosiloxane mixture containing the following components (A3-1) to (A3-3): ： (A3-1)R Ａ a R Ｂ （３－ａ） SiO １／２ (R Ａ is a silicon-bonded functional group containing an acrylic or methacrylic group, and R Ｂ is R Ａ and a is a number ranging from 1 to 3). ＲＡ units) and SiO ４／２ Resinous organosiloxanes having acrylic or methacrylic groups, containing siloxane units (Q units) represented by the formula: (A3-2) R Ｂ´ ３ SiO １／２ (R Ｂ´ is R Ａ is a monovalent organic group other than R Ｂ´ at least one of which is an alkenyl group Ａｌｋ units) and SiO ４／２ and an alkenyl-containing resinous organopolysiloxane containing siloxane units (Q units) represented by the formula: (A3-3) Linear organopolysiloxane having two alkenyl groups in the molecule (B) 1 to 50 parts by mass of a siloxane component that does not contain a carbon-carbon multiple bond in the molecule (C) Photoradical polymerization initiator: 0.1 to 10 parts by mass A curable organopolysiloxane composition comprising:

2. Furthermore, (D) one or more alkenyl groups are contained in the molecule, and R ３ SiO １／２ (wherein R each independently represents a monovalent organic group), and siloxane units (M units) represented by the formula: ４／２ 0 to 50 parts by mass of an organopolysiloxane resin containing siloxane units (Q units) represented by the formula:

2. The curable organopolysiloxane composition of claim 1, comprising:

3. 2. The curable organopolysiloxane composition according to claim 1, further comprising (E) an organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms in the molecule and (F) a hydrosilylation reaction catalyst.

4. 2. The curable organopolysiloxane composition according to claim 1, wherein at least a portion of component (A) is (A1-1) a resin-linear structure-containing organopolysiloxane block copolymer having a structure in which silicon atoms constituting the resinous organosiloxane block X and the linear organosiloxane block Y are linked by siloxane bonds or silalkylene bonds.

5. At least a part of the component (A) is (A1-2)R Ｂ´´ ３ SiO １／２ (R Ｂ´´ is an alkyl group or a phenyl group), the above M ＲＡ Unit, M Ａｌｋ and Q units, and ＲＡ Units and M Ａｌｋ 2. The curable organopolysiloxane composition according to claim 1, which is a resin-linear structure-containing organopolysiloxane block copolymer characterized by containing resinous organosiloxane blocks X in which the sum of the amounts of the units is in the range of 0.5 to 2.0 moles.

6. At least a portion of the component (A) is a resinous organosiloxane block (A1-1-1) comprising the resinous organosiloxane block X and {R Ｃ ２ SiO ２ / ２ } β１ (R Ｃ β is a monovalent organic group, and β1 is a number in the range of 5 to 5,000), and the block X and the block Y are linked by a siloxane bond between silicon atoms.

7. At least a portion of the component (A) is (A1-3) M per 1 mole of Q units ＲＡ 2. The curable organopolysiloxane composition according to claim 1, which is a resin-linear structure-containing organopolysiloxane block copolymer characterized by containing a resinous organosiloxane block X in an amount of 0.02 to 0.50 moles of units.

8. Silicon atom-bonded functional group R in component (A) Ａ 2. The curable organopolysiloxane composition according to claim 1, wherein: is a functional group represented by the following general formula (1): General formula (1): 【Chemistry 1】 [In the formula, R １ each independently represents a hydrogen atom, a methyl group, or a phenyl group; R ２ each independently represents an alkyl group or an aryl group. １ Ha -O(CH ２ ) ｍ - (m is a number ranging from 0 to 3). Z ２ is bonded to a silicon atom constituting the main chain of polysiloxane, where * is -C ｎ H ２ｎ - (n is a number ranging from 2 to 10).

9. 2. The curable organopolysiloxane composition according to claim 1, wherein component (B) is one or more siloxane components containing no carbon-carbon multiple bonds selected from the following components (B1) to (B3): (B1) R in the molecule ３ SiO １／２ (wherein R each independently represent a monovalent organic group containing no carbon-carbon multiple bonds), and siloxane units (M units) represented by the formula: ４／２ wherein the ratio of the amount of M units to 1 mole of Q units is in the range of 0.5 to 2.

0. (B2) Linear or branched diorganopolysiloxane (B3) An organopolysiloxane resin in which the components (B1) and (B2) are linked by siloxane bonds.

10. 2. The curable organopolysiloxane composition according to claim 1, wherein at least a portion of component (B) is (B3-1) a condensation reaction product of component (B1) and component (B2) having a number average molecular weight of 100,000 or more.

11. 2. The curable organopolysiloxane composition according to claim 1, which is heat-curable and photo-curable by irradiation with high-energy rays.

12. 2. The curable organopolysiloxane composition according to claim 1, wherein, when the organopolysiloxane semi-cured product obtained by the heat curing reaction is brought into close contact with another substrate, the adhesive strength to the substrate decreases by 50% or more after the photocuring reaction accompanied by irradiation with high-energy rays.

13. An organopolysiloxane pressure-sensitive adhesive composition comprising the curable organopolysiloxane composition according to any one of claims 1 to 12.

14. An organopolysiloxane pressure-sensitive adhesive layer obtained by curing or semi-curing the curable organopolysiloxane composition according to any one of claims 1 to 12.

15. Step (I): applying the organopolysiloxane pressure-sensitive adhesive composition according to claim 13 onto a substrate; Step (II): semi-curing the organopolysiloxane pressure-sensitive adhesive composition applied in Step (I) by a heat curing reaction; Step (III): A step of irradiating the semi-cured product obtained in step (II) with high-energy rays to further cure it through a photocuring reaction. wherein the adhesive strength of the semi-cured product obtained in step (II) to other substrates is changed by irradiation with high-energy rays in step (III).

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