Ultraviolet-active silicone composition and method for producing adhesive member using same

Abstract

Provided is a method for producing an adhesive member, the method comprising a step for applying, to a first substrate layer, an ultraviolet-curable silicone composition comprising (A) an organopolysiloxane containing an unsaturated group, (B) an organohydrogenpolysiloxane, and (C) an ultraviolet-active hydrosilylation platinum catalyst having as a ligand a cyclopentadienyl group to which a condensed aromatic hydrocarbon group is bonded, and the method comprising, in random order, (i) a step for bonding the first substrate layer to which the ultraviolet-curable silicone composition has been applied to a second substrate layer with a layer of the ultraviolet-curable silicone composition interposed therebetween; (ii) a step for subjecting the ultraviolet-curable silicone composition applied to the first substrate layer to a treatment under a pressure less than the atmospheric pressure; and (iii) a step for irradiating the ultraviolet-curable silicone composition applied to the first substrate layer with ultraviolet rays. Also provided are an adhesive comprising a silicone composition having excellent curability, and an adhesive member having high adhesiveness and high reliability as a member.

Description

Ultraviolet-activated silicone composition and method for producing adhesive member using same

[0001] The present invention relates to an ultraviolet-activatable silicone composition as an adhesive and a method for producing an adhesive member using the same.

[0002] In recent years, flat-panel image display devices such as liquid crystal, plasma, and organic electroluminescence (EL) display devices have been attracting attention. A flat-panel image display device typically has a display area (image display unit) between a pair of substrates, at least one of which is optically transparent, such as glass, and in which a large number of pixels composed of semiconductor layers, phosphor layers, or light-emitting layers constituting active elements are arranged in a matrix. Generally, the periphery of this display area (image display unit) and a protective unit made of glass or optical plastic, such as acrylic resin, are hermetically sealed with an adhesive. UV-curable resin compositions used as adhesives include UV-curable acrylic resins and UV-curable silicone resin compositions (see Patent Document 1).

[0003] UV-curable silicone resin compositions can utilize a platinum-catalyzed hydrosilylation reaction, and although a means for sufficiently curing areas that are not exposed to UV light may be required, they are used as compositions that can be cured under relatively mild conditions (Patent Documents 2 to 5).

[0004] Japanese Patent Application Laid-Open No. 2008-282000 International Publication No. 2023 / 112925 Special Publication No. 2023-514372 Japanese Patent Application Laid-Open No. 2020-158548 Japanese Patent Application Laid-Open No. 2001-89491

[0005] UV-curable silicone compositions can be efficiently and uniformly cured at room temperature and are used for optical bonding and as encapsulants for LEDs. Here, bonding of components often involves a process of placing the composition under reduced pressure to remove highly volatile substances, such as air bubbles and solvents, that may be present in the adhesive, thereby achieving uniform and favorable adhesive strength. However, the inventors' investigations have revealed that conventional UV-curable silicone compositions, such as those used in the above-mentioned patent documents, can exhibit reduced curing properties when placed under reduced pressure. In particular, as image display devices have become thinner in recent years, the thickness of the adhesive layer must also be reduced. However, when the adhesive layer is thin, the reduction in curing properties is significant when the composition is subjected to reduced pressure. The curing properties of UV-curable silicone compositions can also affect their adhesive properties, and there is a demand for compositions that improve this aspect.

[0006] The present invention aims to overcome the above problems by providing an adhesive made from a silicone composition with excellent curing properties, and also to provide an adhesive member that is highly adhesive and highly reliable as a member, and a method for producing the same.

[0007] The inventors of the present invention have found that when conventional UV-curable silicone compositions are placed under reduced pressure, some of the platinum catalyst used in the curing reaction volatilizes. To solve this problem, they have designed a catalyst that is more suitable. Specifically, they have found that a platinum complex having a cyclopentadienyl group substituted with a fused-ring aromatic hydrocarbon as a ligand is effective as a catalyst.

[0008] The present invention provides an adhesive made from a silicone composition with excellent curing properties, an adhesive member with high adhesiveness and high reliability as a member, and a method for producing the same. That is, the present invention relates to the inventions described in the following items. [1] A method for producing an adhesive member, comprising the step of applying to a first substrate layer an ultraviolet-curable silicone composition containing: (A) an organopolysiloxane containing at least two unsaturated groups bonded to silicon atoms per molecule; (B) an organohydrogenpolysiloxane containing at least three hydrogen atoms bonded to silicon atoms per molecule; and (C) an ultraviolet-activated hydrosilylation platinum catalyst having, as a ligand, a cyclopentadienyl group bonded to a condensed aromatic hydrocarbon group; and the method comprising, in any order, the steps of: (i) bonding the first substrate layer to which the ultraviolet-curable silicone composition has been applied to a second substrate layer via the layer of ultraviolet-curable silicone composition; (ii) subjecting the ultraviolet-curable silicone composition applied to the first substrate layer to a pressure less than atmospheric pressure; and (iii) irradiating the ultraviolet-curable silicone composition applied to the first substrate layer with ultraviolet light. [2] The method according to [1] above, wherein steps (i), (ii), and (iii) are carried out in the order of step (ii), step (iii), and step (i). [3] The method according to [1] above, wherein steps (i), (ii), and (iii) are carried out in the order of step (iii), step (ii), and step (i). [4] The method according to any one of [1] to [3] above, wherein step (iii) is a step of irradiating with ultraviolet light having a wavelength of 365 nm or longer. [5] The method according to any one of [1] to [4] above, wherein component (A) is a linear organopolysiloxane. [6] The method according to any one of [1] to [5] above, wherein the unsaturated group in the organopolysiloxane of component (A) is an alkenyl group. [7] The method according to any one of [1] to [6] above, wherein the ratio of the amount of substance of hydrogen directly bonded to silicon contained in component (B) to the amount of unsaturated group contained in component (A) (H / Vi ratio) is in the range of 0.2 to 2.0.[8] The method according to any one of [1] to [7] above, wherein the ultraviolet-activated platinum hydrosilylation catalyst (C) is [1-methyl-3-(2'-naphthyl)-cyclopentadienyl]trimethylplatinum or [1-methyl-3-(9'-phenanthryl)-cyclopentadienyl]trimethylplatinum. [9] The method according to any one of [1] to [8] above, wherein the first substrate or the second substrate is selected from the group consisting of epoxy resin, polyester resin, polycarbonate resin, acrylic resin, polarizing plate, and glass.

[10] An ultraviolet-curable silicone composition for bonding substrates, comprising: (A) an organopolysiloxane containing at least two silicon-bonded unsaturated groups per molecule, (B) an organohydrogenpolysiloxane containing at least three silicon-bonded hydrogen atoms per molecule, and (C) an ultraviolet-activated hydrosilylation platinum catalyst having, as a ligand, a cyclopentadienyl group to which a condensed aromatic hydrocarbon group is bonded.

[11] The ultraviolet-curable silicone composition according to

[10] , wherein the ultraviolet-activated hydrosilylation platinum catalyst (C) is [1-methyl-3-(2'-naphthyl)-cyclopentadienyl]trimethylplatinum or [1-methyl-3-(9'-phenanthryl)-cyclopentadienyl]trimethylplatinum.

[12] A member having a layer bonded with the ultraviolet-curable silicone composition according to

[10] or

[11] .

[13] An ultraviolet-curable silicone composition comprising: (A) an organopolysiloxane containing, per molecule, at least two unsaturated groups bonded to silicon atoms; (B) an organohydrogenpolysiloxane containing, per molecule, at least three hydrogen atoms bonded to silicon atoms; and (C) an ultraviolet-activated hydrosilylation platinum catalyst having, as a ligand, a cyclopentadienyl group bonded to a condensed aromatic hydrocarbon group; wherein the content of an organic solvent that is liquid at room temperature and normal pressure and volatilizes under reduced pressure is 0 mass % relative to the total composition.

[0009] The present invention will be described in detail below for each item, such as a composition for bonding substrates, a bonding method, etc. In this specification, the term "to" indicating a range of values ​​is used to mean that the values ​​before and after it are included as the lower limit and upper limit, respectively.

[0010] As used herein, "organic group" refers to a group containing carbon. The valence of an organic group is indicated by describing it as "n-valent," where n is any natural number. Thus, for example, a "monovalent organic group" refers to a carbon-containing group having only one bond. The bond may be possessed by an element other than carbon. Even when the valence is not specifically specified, a person skilled in the art can understand the appropriate valence from the context.

[0011] As used herein, the term "hydrocarbon group" refers to a group containing carbon and hydrogen, with at least one hydrogen atom removed from the molecule. Such hydrocarbon groups are not particularly limited, but include hydrocarbon groups having 1 to 20 carbon atoms, such as aliphatic hydrocarbon groups and aromatic hydrocarbon groups, which may be substituted with one or more substituents. The "aliphatic hydrocarbon group" may be linear, branched, or cyclic, and may be saturated or unsaturated. The hydrocarbon group may also contain one or more ring structures. The hydrocarbon group may have one or more heteroatoms or structures containing heteroatoms, such as nitrogen atoms (N), oxygen atoms (O), sulfur atoms (S), silicon atoms (Si), amide bonds, sulfonyl bonds, siloxane bonds, carbonyl groups, and carbonyloxy groups, at its terminals or in the molecular chain.

[0012] As used herein, the substituent of the "hydrocarbon group" is not particularly limited, but examples thereof include a halogen atom; a C １－６ Alkyl group, C ２－６ Alkenyl group, C ２－６ Alkynyl group, C ３－１０ Cycloalkyl group, C ３－１０ Unsaturated cycloalkyl groups, 5- to 10-membered heterocyclyl groups, 5- to 10-membered unsaturated heterocyclyl groups, C ６－１０ Examples include groups selected from aryl groups and 5- to 10-membered heteroaryl groups.

[0013] In this specification, alkyl groups and phenyl groups may be unsubstituted or substituted unless otherwise specified. Substituents for such groups are not particularly limited, but include, for example, halogen atoms, C １－６ Alkyl group, C ２－６ Alkenyl group and C ２－６ alkynyl groups.

[0014] [UV-Curable Silicone Composition] Component (A) The UV-curable silicone composition of the present invention contains, as component (A), at least one organopolysiloxane containing at least two unsaturated groups bonded to silicon atoms per molecule. Component (A) functions as the base polymer of the UV-curable silicone composition. The unsaturated group can be present at any position in the polyorganosiloxane molecule. For example, the unsaturated group may be at the molecular terminal, or may be present as a side chain at a position other than the terminal. In the case of a linear polyorganosiloxane, at least one unsaturated group is preferably present at each end of the molecular main chain of component (A). In this specification, the molecular main chain of component (A) refers to the relatively longest bonding chain in the molecule of component (A).

[0015] The type of unsaturated group is not particularly limited as long as it is a functional group that undergoes an addition reaction with component (B), which will be described later, and an alkenyl group is a typical example. The unsaturated group possessed by the organopolysiloxane of component (A) is preferably an alkenyl group. The type of alkenyl group is not particularly limited as long as it has a carbon-carbon double bond and is capable of undergoing an addition reaction. The number of carbon atoms in the alkenyl group is preferably 2 to 20, more preferably 2 to 8, and even more preferably 2 to 6. The alkenyl group may have a branched or cyclic structure. The carbon-carbon double bond in the hydrocarbon constituting the alkenyl group can be located at any position. From the standpoint of reactivity, the carbon-carbon double bond is preferably located at the terminal of the group. A preferred example of an alkenyl group is a vinyl group, as this facilitates the synthesis of polyorganosiloxanes.

[0016] The molecular skeleton of component (A) is not particularly limited as long as the main skeleton is a siloxane bond. The siloxane of the molecular skeleton may be linear, branched, cyclic, or a combination thereof, and may form a molecular skeleton with three-dimensional expansion. Component (A) is preferably a linear organopolysiloxane. The siloxane skeleton may be interrupted by a divalent organic group. Hereinafter, in explaining the structure of a siloxane compound, the structural units of the siloxane compound may be referred to by the following abbreviations. Hereinafter, these structural units may be referred to as "M unit", "D unit", etc., respectively. M: -Si(CH ３ ) ３ O １／２ M Ｈ : -SiH(CH ３ ) ２ O １／２ M Ｖｉ :-Si(CH=CH ２ ) (CH ３ ) ２ O １／２ D: Si(CH ３ ) ２ O ２／２ D Ｈ : SiH(CH ３ ) O ２／２ T: Si(CH ３ ) O ３／２ Q: SiO ４／２ Hereinafter, in this specification, the siloxane compound is constructed by combining the above structural units, but may at least partially contain those in which the methyl groups of the above structural units are replaced with other groups such as halogens such as fluorine, hydrocarbon groups such as phenyl groups, etc. In this case, to indicate a state of being replaced with a substituent, the D units replaced with phenyl groups will be referred to as D Ｐｈ It can also be written as, for example, D Ｐｈ ２０ D ２０ When written as "D", the notation is intended to mean that a total of 20 phenyl groups are contained in the 40 D units. ＰｈIt is not intended that 20 units be followed by 20 D units. Each unit may be arranged in any order, and SiPh ２ O ２／２ (D Ｐｈ２ It is understood that the siloxane compound can have a variety of three-dimensional structures due to the T units or Q units, but component (A) can have a linear molecular skeleton formed by any combination of the above M and D units.

[0017] In one embodiment of the present invention, component (A) is not particularly limited as long as it has an average of two or more silicon-bonded unsaturated groups, particularly alkenyl groups, per molecule and is capable of forming a network structure by addition reaction with hydrosilyl groups (Si—H groups) in component (B) described below. Component (A) is typically represented by the general formula (1): (R １ ) ｍ (R ２ ) ｎ SiO （４－ｍ－ｎ）／２ (1) (wherein, R １ is an unsubstituted or substituted monovalent hydrocarbon group having no aliphatic unsaturated bonds; R ２ is an unsaturated group, preferably an alkenyl group; m is an integer of 0 to 2; and n is an integer of 1 to 3, with the proviso that m+n is 1 to 3).

[0018] A specific example of the component (A) is a compound represented by the following formula (2): (R ａ ) ３－ｐ R ｐ Si-O-(Si(R) ｒ (R ａ ) ２－ｒ O) ｎ -SiR ｑ (R ａ ) ３－ｑ ...(2) (In the formula, R ａare each independently an unsaturated group, preferably an alkenyl group; R is each independently a monovalent organic group; p and q are each independently 0, 1, or 2; r is each independently 0, 1, or 2; and n is a number that provides a viscosity of 0.1 to 500 Pa·s at 23°C. Examples of suitable polyorganosiloxanes include linear polyorganosiloxanes represented by the following formula: R is preferably a hydrocarbon group, particularly an alkyl group, an alkenyl group, or an aryl group. From the viewpoint of controlling physical properties such as refractive index, at least a portion of R may be an aryl group such as a phenyl group. Polyorganosiloxanes in which all R are methyl are preferably used due to their ease of availability, but from the viewpoint of adjusting the refractive index, 1 to 40 mol% of R is preferably C. ６ ~C １２ It is preferably an aryl group, and from the viewpoint of viscosity and thixotropy, 1 to 20 mol % of R is C. ６ ~C １２ With regard to the position of the unsaturated group (alkenyl group), a polyorganosiloxane in which r is 2 in the above formula (2), that is, a linear polyorganosiloxane in which at least one unsaturated group (alkenyl group) exists only at both ends of the molecule, is preferred.

[0019] As the polyorganosiloxane having an unsaturated group, it is preferable that in the formula (2), p and q are 2 and r is 2, i.e., one at each end of the molecule, for a total of two unsaturated groups, preferably alkenyl groups, particularly vinyl groups. Polyorganosiloxanes that can be used as such component (a) can be commercially available. Polyorganosiloxanes into which curable functional groups have been introduced by known reactions can also be used. As component (A), only one type of compound can be used, or two or more types of compounds can be mixed and used, depending on the position or type of the substituent, degree of polymerization, etc. Since component (A) is a polyorganosiloxane, it can also be a mixture of polyorganosiloxanes having various degrees of polymerization.

[0020] The amount of component (A) blended is not particularly limited, so long as it is an amount that results in a handleable viscosity range for the UV-curable silicone composition. Based on the amount of component (A), the amounts of the other components blended can be appropriately set within the preferred ranges shown below.

[0021] Component (B) The UV-curable silicone composition of the present invention contains, as a crosslinking agent, a compound that is reactive with the curable functional groups of component (A) (hereinafter, sometimes simply referred to as "component (B)"). By including a crosslinking agent, the physical properties of the cured product obtained from the curable composition, such as tensile strength and elastic modulus, are improved. Component (B) is an organohydrogenpolysiloxane that has at least three hydrogen atoms bonded to silicon atoms (Si-H bonds) per molecule as crosslinking groups. Examples of component (B) include organohydrogenpolysiloxanes obtained by combining any number and type of structural units represented by the following formula, and having a total of three or more Si-H bonds. (H （３－ａ） R １ ａ SiO １／２ ) (M Ｈ Unit) (R １ ３ SiO １／２ ) (HR １ SiO ２／２ ) (D Ｈ Unit) (R １ ２ SiO ２／２ ) (HSiO ３／２ ) (R １ SiO ３／２ ) (SiO ４／２ ) (In each of the above formulas, R １ each independently represents an unsubstituted or substituted monovalent hydrocarbon group having no aliphatic unsaturated bonds, and a is 1 or 2.

[0022] A preferred example of component (B) is a linear organohydrogenpolysiloxane having an Si—H bond at a position other than the terminal of the molecular chain, as represented by the following formula (3): (R １ ３ SiO １／２ ) ２ (HR １SiO ２／２ ) ｃ (R １ ２ SiO ２／２ ) ｄ ...(3) (wherein, R １ (where a is as defined above, c is a number of 3 or more, and d is a number of 0 or more.) The number of Si-H bonds as crosslinking groups that component (B) has per molecule is 3 or more, with at least one in the side chain, and therefore a network structure can be formed by the crosslinking reaction. Only one type of component (B) may be used, or two or more types may be used simultaneously.

[0023] R １ R each independently represents an unsubstituted or substituted monovalent hydrocarbon group that does not have an aliphatic unsaturated bond. １ As R, those having a hydrocarbon group, for example, an alkyl group or an aryl group, particularly a methyl group or a phenyl group, are preferred. １ At least a part of these may be aryl groups such as phenyl groups.

[0024] Another example of component (B) is a linear organohydrogenpolysiloxane having a terminal Si—H bond, represented by the following formula (4): (H （３－ａ） R １ ａ SiO １／２ ) ｂ (R １ ３ SiO １／２ ) ２－ｂ (HR １ SiO ２／２ ) ｅ (R １ ２ SiO ２／２ ) ｄ ...(4) (In the formula, R １ , a and d are as defined above, b is 0, 1 or 2, and e is a number of 1 or more).

[0025] The siloxane skeleton in the organohydrogenpolysiloxane is preferably a linear skeleton in the main part. The main chain of such organohydrogenpolysiloxanes is a linear skeleton, but may also have a branched structure as a substituent. The number of hydrogen groups (i.e., equivalent to Si—H bonds) bonded to silicon atoms contained in one molecule is three or more, with an average of five or more per molecule being more preferred, and an average of eight or more being even more preferred. Other conditions of the organohydrogenpolysiloxane, such as the organic groups other than hydrogen groups, bonding positions, degree of polymerization, and structure, are not particularly limited. In the case of linear organohydrogenpolysiloxanes, when the value of c+d+2 in the above formula (3) is expressed as the degree of polymerization, a degree of polymerization in the range of 5 to 200, particularly 10 to 120, is preferred, as this tends to further improve the handleability of the resulting composition. Specific examples of organohydrogenpolysiloxanes that can be used include those having a unit (M Ｈ or D Ｈ The organohydrogenpolysiloxane has a linear skeleton and contains 8 or more hydroxyl groups (units) and a degree of polymerization in the range of 10 to 120.

[0026] The amount of component (B) can be designed to fall within an appropriate range, using the criteria described below, depending on the amount of unsaturated groups in component (A). Component (B) can be classified based on the position or type of crosslinking group, the degree of polymerization of the organohydrogenpolysiloxane, etc., and either a single compound or a mixture of two or more compounds can be used. Component (B) can also be a mixture of organohydrogenpolysiloxanes with various degrees of polymerization.

[0027] Component (B) is a hydroxyl group having both ends thereof （３－ａ） R １ ａ SiO １／２ Unit or R １ ３ SiO １／２ The intermediate unit is blocked by at least one HR １ SiO ２／２ Units and any number of R １２ SiO ２／２ It is a linear organohydrogenpolysiloxane consisting of units. At least one hydrogen atom bonded to a silicon atom is present in the intermediate unit, but the remaining two hydrogen atoms may be present at the terminals or in the intermediate unit. As in the above formula (3), it is preferable that the hydrogen atom bonded to the silicon atom is present in the intermediate unit.

[0028] The component (B) is (B1-1), which has both ends blocked with M units (trimethylsiloxane units) and an intermediate unit of D Ｈ (B1-2) a linear polymethylhydrogensiloxane consisting only of units (methylhydrogensiloxane units), (B1-3) a linear polymethylhydrogensiloxane having both ends blocked with M units (trimethylsiloxane units) and intermediate units consisting of D units (dimethylsiloxane units) and D Ｈ Particularly preferred is a linear polymethylhydrogensiloxane consisting solely of units (methylhydrogensiloxane units) in which the methylhydrogensiloxane units are present in an amount of 0.1 to 3.0 moles per mole of dimethylsiloxane units. Component (B) may be a single compound or a combination of two or more compounds.

[0029] The amount of component (B) is preferably such that there are 0.2 to 2.0 hydrogen atoms directly bonded to silicon atoms per curable functional group (alkenyl group) in component (A). If the number is less than 0.2, curing may not proceed at a sufficient rate. If the number is more than 2.0, the cured product may become too hard and may also have adverse effects on post-curing physical properties. In other words, the amount of polyorganosiloxane having alkenyl groups (especially vinyl groups) in the molecule can be adjusted by adjusting the ratio of the amount of Si-H bonds to the amount of vinyl groups in the organohydrogenpolysiloxane (H / Vi ratio). The H / Vi ratio is more preferably in the range of 0.2 to 2.0, and even more preferably in the range of 0.5 to 1.7. By setting the H / Vi ratio at 0.5 or higher, curing can be achieved at a sufficient rate and better adhesion to various substrates can be achieved. Furthermore, by setting the H / Vi ratio to 2.0 or less, the composition can be cured to a sufficient extent, the hardness can be maintained at an appropriate level, and heat resistance and better adhesiveness can be maintained.

[0030] Component (C) The composition of the present invention contains a curing catalyst capable of catalyzing the crosslinking reaction between component (A) and component (B) (hereinafter, sometimes simply referred to as "component (C)"). The curing catalyst used is an ultraviolet-activated hydrosilylation platinum catalyst having a condensed aromatic hydrocarbon group, preferably a cyclopentadienyl group bonded to a naphthyl group, as a ligand. The amount of this catalyst is 0.1 to 1000 ppm of platinum element relative to component (A). If the amount is less than 0.1 ppm, the composition may not be sufficiently catalytically efficient to cure, and if the amount exceeds 1000 ppm, no significant improvement in the curing rate can be expected.

[0031] Specific examples of the curing catalyst include those represented by the following formula [(R ｘ ) ｘ (R ｙ ) ｙ H ４－ｘ－ｙ C ５ ]Pt(R ｚ ) ３ (In the formula, R ｘ is a fused aromatic hydrocarbon group having 7 to 20 carbon atoms, R ｙ is a fused aromatic hydrocarbon group having 7 to 20 carbon atoms or an aliphatic hydrocarbon group having 1 to 22 carbon atoms, R ｚ are each independently an aliphatic hydrocarbon group having 1 to 22 carbon atoms or a trialkylsilyl group, x is an integer of 1 to 3, y is an integer of 0 to 3, and x+y is an integer of 1 to 4, and when x or y is 2 or 3, each R ｘ or R ｙ may be the same or different), and

[0032] group R ｘ The fused aromatic hydrocarbon group as the aromatic hydrocarbon group may be any group containing a structure in which two or more aromatic rings are fused together, and may be a naphthyl group (C １０ H ７ ), a phenanthryl group (C １４ H ９ ), anthracenyl group (C １４ H ９ ), a pyrenyl group (C １６ H ９) and the like, but a naphthyl group or a phenanthryl group is preferred, and a naphthyl group is particularly preferred. These groups may be further substituted with one or more substituents such as a methyl group, an isopropyl group, a tert-butyl group, a phenyl group, etc. The substituent R of the cyclopentadienyl group ｘ The present invention is based on the discovery that by using a platinum complex having a condensed aromatic hydrocarbon group, particularly a naphthyl group, as the platinum complex, the platinum complex is not lost from the composition due to sublimation or the like, even under reduced pressure, and the curability of the UV-curable silicone composition is not impaired.

[0033] group R ｙ , R ｚ As the aliphatic hydrocarbon group having 1 to 22 carbon atoms, an alkyl group having 1 to 6 carbon atoms is preferred, and a methyl group is more preferred. ｚ Examples of the alkyl group include a trialkylsilyl group having three alkyl groups each having 1 to 6 carbon atoms. The alkyl groups bonded to silicon may be different from each other, but a trimethylsilyl group is preferred.

[0034] The platinum ligand [(R ｘ ) ｘ (R ｙ ) ｙ H ４－ｘ－ｙ C ５ ] forms a substituted cyclopentadienyl group and is bonded to platinum by a σ bond. In other words, any one of the carbon atoms forming the five-membered ring of the cyclopentadienyl group forms a bond with platinum. Therefore, the substituent R ｘ and R ｙ The total number of groups is 1 to 4. ｘ and R ｙ The substitution position of R ｘ or R ｙ There is no particular limitation as to which carbon atom is bonded to which carbon atom of the cyclopentadienyl group.

[0035] More specific examples of the curing catalyst include [(1'-naphthyl)-cyclopentadienyl]trimethylplatinum; [(2'-naphthyl)-cyclopentadienyl]trimethylplatinum; [1-methyl-3-(1'-naphthyl)-cyclopentadienyl]trimethylplatinum; [1-methyl-3-(2'-naphthyl)-cyclopentadienyl]trimethylplatinum; [(9'-phenanthryl)-cyclopentadienyl]trimethylplatinum; Examples of suitable curing catalysts include 1-methyl-3-(9'-phenanthryl)-cyclopentadienyl]trimethylplatinum; [1-(2'-anthracenyl)-3-methyl-cyclopentadienyl]trimethylplatinum; [(2'-anthracenyl)-cyclopentadienyl]trimethylplatinum; [(1'-pyrenyl)-cyclopentadienyl]trimethylplatinum; and [1-methyl-3-(1'-pyrenyl)-cyclopentadienyl]trimethylplatinum. More preferred curing catalysts are [1-methyl-3-(2'-naphthyl)-cyclopentadienyl]trimethylplatinum or [1-methyl-3-(9'-phenanthryl)-cyclopentadienyl]trimethylplatinum. Other curing catalysts may be used, as long as they can be represented by the above formula, and two or more curing catalysts may be used in combination.

[0036] The platinum complex may be commercially available or synthesized by known means. For example, the desired platinum complex can be obtained by reacting a lithium salt of a substituted cyclopentadiene with a platinum(IV) complex having a leaving group such as a halogen or phosphate. Furthermore, for the purpose of achieving ease of handling and uniformity in the composition, a solution of the platinum complex dissolved in a solvent such as aromatic hydrocarbons (e.g., toluene), hydrocarbons (e.g., heptane), ethers, ketones, or alcohols may be used. However, in order to reduce the amount of volatile components in the composition, it is preferable to use a small amount of solvent, and it is more preferable to use the platinum complex as a solid rather than as a solution.

[0037] Depending on the application of the UV-curable silicone composition, the activity of the catalyst can be suppressed by adding a reaction inhibitor to obtain a longer pot life. Known reaction inhibitors for platinum group metals include acetylene alcohols such as 2-methyl-3-butyn-2-ol, 3,5-dimethyl-1-hexyn-3-ol, and 1-ethynyl-2-cyclohexanol, diallyl maleate, and tertiary amines such as tetramethylethylenediamine and pyridine.

[0038] Composition The ultraviolet-curable silicone composition of the present invention contains the above-mentioned components (A) to (C). In particular, the present invention relates to an ultraviolet-curable silicone composition containing the above-mentioned components (A) to (C), in which the content of organic solvents that volatilize under reduced pressure is 0.5% by mass or less, preferably 0.1% by mass or less, relative to the total composition. While preferred embodiments of the essential components (A) to (C) are as described above, components (A) and (B) can be appropriately selected from commercially available or known materials depending on the desired physical properties. For example, from the perspective of controlling the refractive index, it is preferable to introduce phenyl groups into components (A) and (B). In this case, it is preferable to design the composition so that the refractive index of the cured product is 1.56 or less.

[0039] The properties of the UV-curable silicone composition of the present invention are not particularly limited, so long as the components are uniformly mixed and the composition has sufficient fluidity to be applicable to substrates. The viscosity of the composition can be controlled primarily by the viscosity of component (A), and a range of 0.1 to 500 Pa·s is preferred from the viewpoint of ease of use. A viscosity of 0.1 to 50 Pa·s is even more preferred. The UV-curable silicone composition of the present invention is highly stable, exhibiting minimal viscosity fluctuations even after long-term storage and excellent handleability. A composition whose viscosity is 50 Pa·s or less after one week at 80°C in the dark is particularly preferred. The UV-curable silicone composition can be a one-component composition in which all components are mixed together, or a two-component composition in which components (B) and (C) are separately formulated. The choice of whether to use a one-component or two-component composition can be made appropriately, taking into account factors such as workability and curing conditions, and the method for doing so is well known to those skilled in the art.

[0040] The UV-curable silicone composition of the present invention can be blended with other known components as long as they do not impair its purpose and effects. Additives such as flame retardants, adhesion promoters, heat resistance promoters, diluents, organic solvents, inorganic or organic pigments, etc. can be appropriately blended. Siloxane resins that do not fall under the category of component (A) or (B) can also be blended. Examples of such resins include polyorganosiloxanes having only one curable functional group and polyorganosiloxanes without curable functional groups, such as dimethylsiloxane. These resins can be used as diluents.

[0041] <Other Resins> The UV-curable silicone composition may further contain a siloxane resin that does not fall under the category of components (A) and (B). Such a resin can also be used as a diluent for adjusting viscosity. Such a siloxane resin may be a resin obtained by combining the M, D, T, and Q units and that has no or only one curable functional group, particularly a resin represented by the following formula (5): R ａ R ２ Si—O—(SiR ２ O) ｎ -SiR ３...(5) (wherein, R ａ , R, n are as defined in formula (2), and R does not have a curable functional group), or a siloxane having only one curable functional group, represented by formula (6): R ３ Si—O—(SiR ２ O) ｎ -SiR ３ ...(6) (wherein R and n are as defined in formula (2), and R does not have a curable functional group) can be used. By using such a siloxane resin, it is possible to control the hardness of the UV-curable silicone composition when cured, and to control the viscosity of the composition, making it possible to respond to a wide range of handleability and required physical properties.

[0042] The ultraviolet-curable silicone composition can contain such a resin in an amount of, for example, 50 parts by mass or less, specifically 0.1 to 50 parts by mass, and more specifically 1 to 30 parts by mass, per 100 parts by mass of component (A).

[0043] <Polyorganohydrogensiloxane having two silicon-bonded hydrogen atoms in the molecule> The composition can further contain a polyorganohydrogensiloxane having two silicon-bonded hydrogen atoms in the molecule. Such siloxane can function as a chain extender by undergoing an addition reaction with component (A). Examples of such siloxanes are as described for component (B), except that they have two silicon-bonded hydrogen atoms in the molecule. Such siloxanes are those represented by the general formula (3) or (4), （３－ａ） R １ ａ SiO １／２ or HR １ SiO ２／２ Preferably, the molecule contains two units represented by the formula (I) so that the number of Si-H bonds is two.

[0044] The siloxane skeleton in this component may be linear, branched, or cyclic, with linear being preferred. Furthermore, the siloxane in this component has two ends that are each independently R５ ３ SiO １／２ It is blocked by units, and the intermediate unit is R ５ ２ SiO ２／２ units (wherein R ５ are each independently a monovalent hydrocarbon group having no hydrogen atom or aliphatic unsaturated bond, but there are two R ５ The hydrogen atoms bonded to the silicon atoms may be present at the terminals or in intermediate units, but are preferably present at the terminals. Therefore, the siloxane of this component is preferably a polyorganosiloxane in which both terminals are M Ｈ Particularly preferred is a polymethylhydrogensiloxane in which the intermediate unit is composed solely of D units (dimethylsiloxane units).

[0045] <Adhesion Promoter> The UV-curable silicone composition may further contain an adhesion promoter, provided that the addition does not impair the objectives and effects of the present invention. The adhesion promoter is a component that improves the adhesion of the cured composition to substrates such as glass, metal, and plastic. Examples of adhesion promoters include metal alkoxides, compounds having a hydrolyzable silyl group, compounds having a hydrolyzable silyl group and a reactive organic functional group in one molecule, compounds having a silicon-bonded hydrogen atom and a divalent aromatic group in one molecule, compounds having a silicon-bonded hydrogen atom and a reactive organic functional group in one molecule, and / or partial hydrolysis condensates thereof. Examples of metal alkoxides include aluminum alkoxides such as aluminum triethoxide, aluminum tripropoxide, and aluminum tributoxide; and titanium alkoxides such as titanium tetraethoxide, titanium tetrapropoxide, titanium tetraisopropoxide, titanium tetrabutoxide, titanium tetraisobutoxide, and titanium tetraisopropenyl oxide. Examples of organic adhesion promoters include amino group-containing silanes, isocyanurates, and carbasilatrane compounds. Specific examples include tetraethoxysilane, tetramethoxysilane oligomers, vinyltrimethoxysilane, vinyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3,4-epoxycyclohexylethyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-acryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, and 3-methacryloxypropylmethyldiethoxysilane. It is preferable to incorporate less than 5 parts by mass of these components per 100 parts by mass of component (A), the base polymer, in order to prevent an increase in haze, particularly under high temperature and high humidity conditions.

[0046] Further examples of the adhesion promoter include the following: (E1) Si(OR ３ ) ｎ(E2) an organosilicon compound having a group and an epoxy group-containing group, and / or a partial hydrolysis condensate thereof; ３ ) ｎ a silane compound having a group and an aliphatic unsaturated hydrocarbon group, and / or a partial hydrolysis condensate thereof, and (E3) Si(OR ４ ) ４ (E4) A siloxane compound having, in one molecule, at least two hydrogen atoms bonded to a silicon atom and one hydrolyzable group bonded to a siloxane skeleton via a structure containing a heteroatom (in each of the above formulas, R ３ represents an alkyl group having 1 to 4 carbon atoms or a 2-methoxyethyl group; R ４ represents an alkyl group having 1 to 3 carbon atoms; and n is an integer of 1 to 3.

[0047] Each of (E1), (E2), (E3) and (E4) may be used alone or in combination of two or more.

[0048] <<(E1)>> (E1) is a component that is introduced into a crosslinked siloxane structure through a co-hydrolysis / condensation reaction between a silicon-bonded alkoxy group and a silicon-bonded alkoxy group in (E2) and / or (E3), and serves as an epoxy group that exhibits adhesive properties, thereby contributing to improving the adhesive properties of the composition at room temperature, particularly the adhesive properties to plastics.

[0049] R ３ is preferably a methyl group or an ethyl group, with a methyl group being particularly preferred, as it provides good adhesive properties. n is preferably 2 or 3. As the epoxy group-containing group, an aliphatic epoxy group-containing group containing an ether oxygen atom, such as a 3-glycidoxypropyl group, or an alicyclic epoxy group-containing group, such as a 2-(3,4-epoxycyclohexyl)ethyl group, is preferred, as it is easy to synthesize, is not hydrolyzable, and exhibits excellent adhesive properties. Si(OR ３ ) ｎ There may be two or more OR groups in a molecule. ３ The number of OR groups in a molecule is preferably 2 or more. ３The group and the epoxy group-containing group may be bonded to the same silicon atom or to different silicon atoms.

[0050] Examples of (E1) include 3-glycidoxypropyl group-containing alkoxysilanes such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, and 3-glycidoxypropyl(methyl)dimethoxysilane; 2-(3,4-epoxycyclohexyl)ethyl group-containing alkoxysilanes such as 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyl(methyl)dimethoxysilane; partial hydrolysis condensates of these silanes where n is 2 or more; and carbon / silicon bifunctional siloxanes in which some of the methyl groups of linear or cyclic methylsiloxanes have been replaced with trimethoxysiloxy groups or 2-(trimethoxysilyl)ethyl groups and the above-mentioned epoxy group-containing groups.

[0051] <<(E2)>> (E2) is a component that undergoes an addition reaction with (B) during curing of the composition, and is introduced into the siloxane structure crosslinked by the addition reaction with (A) and (B). The alkoxy groups present in the side chains act as adhesive moieties, contributing to improving the adhesiveness of the composition at room temperature, particularly adhesion to metals. Furthermore, the alkoxy groups of (E2) also contribute to introducing (E1) and / or (E3) into the crosslinked siloxane structure through co-hydrolysis and condensation reactions with the alkoxy groups of (E1) and / or (E3). (E2) is a component of Si(OR ３ ) ｎ Preferably, the silane compound is a silane compound having a group and one aliphatic unsaturated hydrocarbon group, and / or a partial hydrolysis condensate thereof.

[0052] R ３is preferably a methyl group or an ethyl group, with a methyl group being particularly preferred, as it provides good adhesion. n is preferably 2 or 3. The aliphatic unsaturated hydrocarbon group is preferably a monovalent group. When the aliphatic unsaturated hydrocarbon group is an alkenyl group such as vinyl, allyl or 3-butenyl, it may be directly bonded to the silicon atom, or, as in 3-acryloxypropyl and 3-methacryloxypropyl, an unsaturated acyloxy group may be bonded to the silicon atom via three or more carbon atoms. As the unsaturated hydrocarbon group-containing group, a vinyl group, a methacryloxypropyl group, etc. are preferred because of their ease of synthesis and handling. Si(OR ３ ) ｎ There may be two or more OR groups in a molecule. ３ The number of OR groups in a molecule is preferably 2 or more. ３ The group and the aliphatic unsaturated hydrocarbon group may be bonded to the same silicon atom or to different silicon atoms.

[0053] Examples of (E2) include alkenylalkoxysilanes such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, methylvinyldimethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, and methylallyldimethoxysilane, and / or partial hydrolysis condensates thereof; (meth)acryloxypropyl(methyl)di- and (meth)acryloxypropyltrialkoxysilanes such as 3-acryloxypropyltrimethoxysilane, 3-acryloxypropyltriethoxysilane, 3-acryloxypropyl(methyl)dimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, and 3-methacryloxypropyl(methyl)dimethoxysilane, and / or partial hydrolysis condensates thereof.

[0054] <<(E3)>> (E3) is a component that further improves the adhesion of the composition to metal at room temperature. ４Examples of the alkyl group include linear or branched alkyl groups such as methyl, ethyl, propyl, and isopropyl, and methyl and ethyl groups are preferred because they are easily available, easy to handle, and have a significant effect of improving adhesion. Furthermore, although (E3) can be used as a tetraalkoxysilane compound alone, it is preferably a partial hydrolysis condensate of a tetraalkoxysilane compound because of its excellent hydrolysis property and low toxicity.

[0055] <<(E4)>> (E4) is a siloxane compound having a silicon-bonded hydrogen atom and a hydrolyzable group, which functions as an adhesion promoter. The hydrolyzable group here is bonded to the siloxane skeleton via a structure containing a heteroatom. (E4) undergoes an addition reaction with component (A) during curing of the composition, and is introduced into the siloxane structure crosslinked by the addition reaction with (A) and (B). As a moiety that exhibits adhesiveness, (E4) contributes to the adhesiveness of the composition at room temperature. However, components corresponding to the aforementioned components (A) or (B) are excluded from this component.

[0056] The "structure containing a heteroatom" is a divalent functional group containing at least one of oxygen, nitrogen, sulfur, and phosphorus. The structure is not particularly limited as long as it contains a heteroatom in the skeleton that connects the hydrolyzable group and the siloxane skeleton with the fewest number of atoms. Examples of structures containing a heteroatom include -CH of a divalent alkylene group. ２ At least one - moiety, ether (-O-), amino (-NR-; where R is a hydrogen atom or a monovalent hydrocarbon group), sulfide (-S-), sulfonyl (-SO ２ -), phosphino (-PR-), ester (-O(C=O)-), thioester (-S(C=O)-), etc.

[0057] As used herein, the term "hydrolyzable group" refers to a group that can undergo a hydrolysis reaction, i.e., a group that can be eliminated from the main skeleton of the compound by a hydrolysis reaction. In (E4), preferably only one hydrolyzable group is contained in the molecule, and the group is bonded to the siloxane skeleton via a structure containing a heteroatom. Examples of hydrolyzable groups include -OR', -OCOR', and -O-N=CR'. ２ , -NR' ２ , —NHR′, epoxy, halogen atoms (in these formulas, R′ represents a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms), etc. Preferred are —OR′ (i.e., an alkoxy group) because it is less likely to corrode various substrates and is chemically stable as a silicone composition. Examples of R′ include unsubstituted alkyl groups such as methyl, ethyl, propyl, isopropyl, n-butyl, and isobutyl; and substituted alkyl groups such as chloromethyl. Among these, alkyl groups, particularly unsubstituted alkyl groups, are preferred, with methyl or ethyl groups being more preferred. That is, in one embodiment, the hydrolyzable group is an alkoxy group such as a methoxy group, ethoxy group, propoxy group, or butoxy group. The hydroxyl group is not particularly limited, but may be one generated by hydrolysis of a hydrolyzable group. Examples of halogen atoms include fluorine, chlorine, bromine, and iodine atoms, with chlorine being preferred among these.

[0058] (E4) is a group consisting of a hydrogen atom bonded to a silicon atom and a group having the following formula: (In each of the above formulas, Q １ represents a linear or branched alkylene group that forms a carbon chain having two or more carbon atoms between the silicon atom and the ester bond; Q ２ represents a linear or branched alkylene group that forms a carbon chain having 3 or more carbon atoms between the oxygen atom and the silicon atom of the structure; R ３ represents an alkyl group having 1 to 4 carbon atoms or a 2-methoxyethyl group.

[0059] Q １is preferably an ethylene group or a 2-methylethylene group because of ease of synthesis and handling. ２ is preferably a trimethylene group because of ease of synthesis and handling. ３ Methyl and ethyl groups are preferred, with methyl being particularly preferred, because they provide good adhesion and the alcohol produced by hydrolysis is easily volatilized.

[0060] In view of ease of synthesis, it is preferable that the hydrogen atom and the structure in the above formula are bonded to different silicon atoms. Therefore, it is preferable that the basic portion of (E4) forms a linear, branched, or cyclic siloxane skeleton. The number of Si-H bonds contained in (E4) is any number of 1 or more, and in the case of a cyclic siloxane compound, 2 or 3 is preferred.

[0061] Examples of (E4) include reaction products of cyclic organohydrogenpolysiloxanes and silane compounds having acrylic or methacrylic groups. Such compounds are preferred because they have established synthetic routes and because it is easy to control the number of Si-H bonds and the number of hydrolyzable groups per molecule, making it easy to uniformly control the physical properties of the entire composition. More specific examples of (E4) include the following compounds: Other components (E4) include the following: Examples of compounds include those having a silicon-bonded hydrogen atom and a reactive organic functional group in one molecule, such as:

[0062] <<Other Adhesion Promoters>> Examples of adhesion promoters other than (E1) to (E4) include metal alkoxides such as aluminum alkoxides such as aluminum triethoxide, aluminum tripropoxide, and aluminum tributoxide; titanium alkoxides such as titanium tetraethoxide, titanium tetrapropoxide, titanium tetraisopropoxide, titanium tetrabutoxide, titanium tetraisobutoxide, and titanium tetraisopropenyl oxide; zirconium acylates such as zirconium octanoate, zirconium tetra(2-ethylhexanoate), and zirconium stearate; zirconium alkoxides (excluding zirconium chelates) such as n-propyl zirconate and n-butyl zirconate; and zirconium chelates such as tributoxyzirconium acetylacetonate, dibutoxyzirconium bis(ethylacetoacetate), zirconium tetraacetylacetonate, zirconium monoacetylacetonate, and zirconium ethylacetoacetate.

[0063] Other adhesion promoters include: Compounds having a hydrolyzable silyl group and a reactive organic functional group in one molecule and / or partial hydrolysis condensates thereof (excluding those corresponding to (E1) to (E4)); (wherein k is an integer of 1 to 3), and compounds having a hydrogen atom bonded to a silicon atom and a divalent aromatic group in one molecule. The adhesive strength can be further increased by using other adhesion promoters in combination.

[0064] The adhesion promoter may be contained in the ultraviolet-curable silicone composition in an amount of, for example, 10 parts by mass or less, specifically 0.01 to 10 parts by mass, and more specifically 0.1 to 5 parts by mass, per 100 parts by mass of component (A). One type of adhesion promoter may be used alone, or two or more types may be used in combination.

[0065] <Solvent> The UV-curable silicone composition may contain an organic solvent that is liquid at room temperature and normal pressure and volatilizes under reduced pressure, as long as the effects of the present invention are not impaired. The solvent used to dissolve the platinum complex of component (C) above can also be treated as the solvent. In this case, the UV-curable silicone composition can be used by dissolving it in an appropriate solvent to a desired concentration depending on its application and purpose. By containing a solvent, the viscosity of the curable composition can be adjusted, improving handleability. However, from the perspective of suppressing the content of volatile components, a small amount of solvent is preferred, and it is more preferable that no solvent is contained. In other words, the UV-curable silicone composition of the present invention preferably contains an organic solvent that is liquid at room temperature and normal pressure and volatilizes under reduced pressure in an amount of 1 mass % or less, more preferably 0 mass %, based on the total composition.

[0066] One aspect of the present invention is the ultraviolet-curable silicone composition for bonding substrates. Accordingly, the present invention provides an adhesive comprising the ultraviolet-curable silicone composition. The adhesive preferably contains an adhesion promoter in addition to the components (A) to (C).

[0067] [Method for manufacturing adhesive member] One aspect of the present invention relates to a method for manufacturing an adhesive member, which includes a step of applying the ultraviolet-curable silicone composition to a first substrate layer, and includes, in any order: (i) a step of bonding the first substrate layer to which the ultraviolet-curable silicone composition has been applied to a second substrate layer via a layer of the ultraviolet-curable silicone composition; (ii) a step of subjecting the ultraviolet-curable silicone composition applied to the first substrate layer to a pressure lower than atmospheric pressure; and (iii) a step of irradiating the ultraviolet-curable silicone composition applied to the first substrate layer with ultraviolet light.

[0068] Substrate: The material of the substrate to which the adhesive containing the ultraviolet-curable silicone composition of the present invention is applied is not particularly limited. Examples of suitable substrates include metals such as aluminum, copper, nickel, iron, brass, and stainless steel; epoxy resins, polyester resins such as polyethylene terephthalate and polybutylene terephthalate (PBT) resins, polycarbonate resins, acrylic resins, polyimide resins, phenolic resins, polyamide resins, polyphenylene sulfide (PPS) resins, and modified polyphenylene ether (PPE) resins; and glass. Among these, it is preferable to use a substrate selected from the group consisting of epoxy resins, polyester resins, polycarbonate resins, acrylic resins, polarizing plates, and glass. If necessary, the wall surfaces of the gaps may be subjected to conventional treatments such as primer treatment, corona treatment, plasma treatment, and excimer treatment. The method of the present invention uses a first substrate to which the ultraviolet-curable silicone composition is applied and a second substrate to be bonded to the first substrate, but the first and second substrates to be bonded may be made of different materials.

[0069] Application to Substrates An adhesive containing a UV-curable silicone composition is applied to a desired thickness on the surface of a component, including a substrate, at a bonding site by methods such as dripping, pouring, casting, extrusion from a container, bar coating, roll coating, slit die coating, screen printing, dipping, brush coating, spraying, or dispensing. Slit die coating, which is particularly suitable for application as a uniform thin film, is used as an application method to substrates. These methods are well known to those skilled in the art. The composition may be applied uniformly over the entire surface of the component, or unevenly or partially, such as in lines, stripes, or dots. The application thickness of the composition is typically 0.01 to 3 mm, preferably 0.05 to 2 mm. When applied to substrates, the UV-curable silicone composition can be used as either a one-component adhesive or a two-component adhesive. When used as a two-component adhesive, it is preferable to mix the components using a commonly used mixing device, such as a static mixer, before applying the composition to the substrate.

[0070] The method of the present invention includes (i) a step of laminating a first substrate layer to which an ultraviolet-curable silicone composition has been applied to a second substrate layer via a layer of ultraviolet-curable silicone composition. The first substrate to which the ultraviolet-curable silicone composition has been applied is laminated to a second substrate to obtain a laminated member. The lamination method is not particularly limited, and any means can be used. The ultraviolet-curable silicone composition may also be applied to the second substrate. In an article using the ultraviolet-curable silicone composition of the present invention as an adhesive, the composition and each substrate only need to have an adhesive portion, and the shape, thickness, etc. of the adhesive portion are not particularly limited. The lamination step may also be performed under reduced pressure or ultraviolet irradiation conditions, as described below.

[0071] The method of the present invention includes (ii) a step of subjecting the UV-curable silicone composition applied to the first substrate layer to a pressure less than atmospheric pressure. The object of the vacuum treatment here may be the first substrate to which the UV-curable silicone composition has been applied before the second substrate is bonded, or the bonded member to which the second substrate is bonded. The conditions for the vacuum treatment are not particularly limited as long as they are sufficient to remove gases such as air and volatile solvents contained in the UV-curable silicone composition. The conditions for the vacuum treatment depend on factors such as the size of the bonded member, but the pressure is preferably less than atmospheric pressure, preferably 30 KPa or less, and more preferably 10 KPa or less. The vacuum treatment time is 10 seconds or more, preferably 30 seconds or more, more preferably 1 minute or more, and can usually be completed in 5 minutes or less. The pressure and time conditions can be combined within a range that achieves the intended purpose. Furthermore, to efficiently remove bubbles and the like, a heat treatment may be performed separately or simultaneously within the heat resistance of the substrate.

[0072] The method of the present invention includes a step (iii) of irradiating the ultraviolet-curable silicone composition applied to the first substrate layer with ultraviolet light. The first substrate or bonded member to which the composition of the present invention is applied can be bonded by curing the composition portion by irradiating it with ultraviolet light. The dose of ultraviolet light is 100 to 10,000 mJ / cm. ２ is preferred, and more preferably 300 to 6,000 mJ / cm ２ and more preferably 500 to 4,000 mJ / cm ２The irradiation dose is a measured value of UVA. Here, UVA refers to ultraviolet light in the range of 315 to 400 nm. The composition exhibits good curability when irradiated with ultraviolet light having a wavelength in the range of 250 to 450 nm, for example. In particular, the ultraviolet-curable silicone composition of the present invention exhibits good curability even when irradiated with relatively low-energy ultraviolet light in the wavelength range of 365 nm or greater. Examples of light sources that emit ultraviolet light of such wavelengths include a high-pressure mercury lamp (UV-7000) and a metal halide lamp (UVL-4001M3-N1) manufactured by Ushio Inc., a metal halide lamp (JM-MTL 2KW) manufactured by JM Tech Co., Ltd. in Korea, an ultraviolet irradiation lamp (OSBL360) manufactured by Mitsubishi Electric Corporation, an ultraviolet irradiator (UD-20-2) manufactured by Japan Storage Battery Co., Ltd., a fluorescent lamp (FL-20BLB) manufactured by Toshiba Corporation, an H bulb, H plus bulb, V bulb, D bulb, Q bulb, and M bulb manufactured by Heraeus, and an LED lamp (HLDL-155UV) manufactured by CCS Corporation.

[0073] The curing time of the composition is generally 30 minutes or less, although it depends on the amount of UV irradiation. Whether or not the curing of the composition has progressed can be judged visually or by qualitatively evaluating whether the surface is tack-free (whether or not it feels sticky when touched). It can also be quantitatively evaluated by measuring the storage modulus G' and loss modulus G". For example, if the time until the storage modulus G' and the loss modulus G" become equal is within 30 minutes at 23°C after UV irradiation, this is preferable because it can be said that the curing time is short and the composition is easy to handle.

[0074] The method of the present invention includes a step of applying the ultraviolet-curable silicone composition to a first substrate layer, and also includes the above steps (i), (ii), and (iii). The method of the present invention only needs to include these three steps, and the order in which steps (i), (ii), and (iii) are performed is not specified, and steps (i), (ii), and (iii) can be performed in any order. For example, steps (i), (ii), and (iii) can be performed in the order of step (i), step (ii), and step (iii), or in the order of step (ii), step (iii), and step (i), or in the order of step (iii), step (ii), and step (i). These steps may be performed consecutively, or two or three steps may be performed simultaneously, for example, by performing lamination under reduced pressure.

[0075] One aspect of the present invention is a member having a layer bonded with the ultraviolet-curable silicone composition. The ultraviolet-curable silicone composition of the present invention uses a platinum catalyst with low volatility, allowing for favorable curing reactions. As a result, articles obtained using the member of the present invention have excellent durability, including water resistance at the bonded surface and sealed areas, making them suitable for use as various components in the electronic materials field. Furthermore, the composition has favorable curing properties, making it suitable for use as an adhesive for bonding image display devices such as liquid crystal, plasma, and organic electroluminescence (EL). The member of the present invention contains a non-volatile platinum catalyst in the adhesive layer containing the ultraviolet-curable silicone composition, and the amount of the platinum catalyst can be measured. The amount of platinum in the adhesive layer depends on the platinum catalyst concentration in the composition, but is generally between 0.1 ppm and 50 ppm.

[0076] The composition of the present invention will be described in more detail through the following examples, but the present invention is not limited to these examples.

[0077] The materials used in the examples and comparative examples are as follows: ＨThe symbols used to describe siloxane compounds such as α,ω-divinylpolydimethylsiloxane and α,ω-dimethylsiloxane have the same meanings as above. Unless otherwise specified, the amounts of the components are expressed in parts by mass. <Polyorganosiloxane resin: component (A)> α,ω-divinylpolydimethylsiloxane; viscosity 3 Pa s <Organohydrogenpolysiloxane: component (B)> MD １７ D Ｈ ２３ Organohydrogenpolysiloxane represented by M <Platinum catalyst: component (C)> [1-methyl-3-(2'-naphthyl)-cyclopentadienyl]trimethylplatinum or [1-methyl-3-(9'-phenanthryl)-cyclopentadienyl]trimethylplatinum <Silane compound (D)> DD Ｈ ３ A compound obtained by addition reaction of 3-methacryloxypropyltrimethoxysilane with a cyclic siloxane represented by the formula:

[0078] Test Example 1: Gel Time Using a viscoelasticity measuring device (MCR302) (manufactured by Anton Paar Japan Co., Ltd.), a composition was ejected onto a lower parallel quartz plate at 23°C. The composition was then sandwiched between upper parallel plates (8 mm in diameter) so that the thickness of the composition was 300 μm, and irradiated with an LED having an irradiation intensity of 100 mW and a wavelength of 365 nm for 10 seconds. The storage modulus G' (Pa) and loss modulus G" (Pa) were measured every second at a frequency of 1 Hz and a strain of 1%, and the time (minutes) until the storage modulus G' and the loss modulus G" became equal was determined as the G'G" cross point, which was also defined as the curing time of the composition.

[0079] Test Example 2: Gel time after reduced pressure The composition was applied to a thickness of 90 μm, and the thin film was left to stand under 1 KPa for 5 minutes. After the pressure was returned to normal pressure, the gel time of the treated composition was measured by the method of Test Example 1.

[0080] [Test Example 3: Tack-free time] Using an LED irradiator (HLDL-120V0-NWPSC manufactured by CCS) with a wavelength of 405 nm, ultraviolet light was irradiated at an irradiation intensity of 200 mW for 20 seconds. The surface was touched every 30 seconds, and the time until curing was confirmed as the tack-free time.

[0081] Preparation of UV-Curable Silicone Composition Example 1 0.05% by weight of [1-methyl-3-(2'-naphthyl)-cyclopentadienyl]trimethylplatinum was added to polyorganosiloxane resin (A), heated to 95°C in an oven, and stirred to obtain a platinum catalyst solution. Polyorganosiloxane resin (A), organohydrogenpolysiloxane (B), platinum catalyst solution, and silane compound (D) were mixed in the proportions shown in the table to obtain composition 1.

[0082] Example 2 An ultraviolet-curable silicone composition was prepared in the same manner as in Example 1, except that the platinum catalyst was changed to the same amount, in terms of elemental platinum, of [1-methyl-3-(9'-phenanthryl)-cyclopentadienyl]trimethylplatinum solution.

[0083] Comparative Example 1: The platinum catalyst was replaced with the same amount of methylcyclopentadienyltrimethylplatinum ([MeCpPtMe ３ An ultraviolet-curable silicone composition was prepared in the same manner as in Example 1, except that the above-mentioned formula (I) was changed to 1.

[0084] Comparative Example 2: The platinum catalyst was replaced with the same amount of pentamethylcyclopentadienyltrimethylplatinum ([Cp ＊ PtMe ３ An ultraviolet-curable silicone composition was prepared in the same manner as in Example 1, except that the above-mentioned formula (I) was changed to 1.

[0085] Comparative Example 3: An attempt was made to prepare a platinum solution in the same manner as in Example 1, and bisacetylacetonatoplatinum ([Pt(acac) ２ ]) showed no solubility. Therefore, a 0.05% solution was prepared using 2-2-methoxyethoxyethanol, and used as a platinum catalyst solution. The platinum catalyst was replaced with the same amount of bisacetylacetonatoplatinum ([Pt(acac) ２ ]), ultraviolet-curable silicone compositions were prepared in the same manner as in Example 1. The results of Test Examples 1 to 3 for each of the Examples and Comparative Examples are shown in Table 1.

[0086]

[0087] As can be seen from Table 1, the UV-curable silicone composition of the present invention using a specific platinum catalyst had a short gelation time and excellent curing properties. Furthermore, its curability was not impaired even after vacuum treatment, demonstrating its suitability for the manufacture of components that involve vacuum treatment steps during bonding. Furthermore, the UV-curable silicone composition using this specific platinum catalyst also exhibited excellent curing properties when irradiated with long-wavelength UV light. On the other hand, compositions using other platinum catalysts cured but took a somewhat longer time to gel, and this tendency was further exacerbated when subjected to vacuum treatment.

Claims

1. A method for producing an adhesive member, comprising the step of applying to a first substrate layer an ultraviolet-curable silicone composition containing: (A) an organopolysiloxane containing at least two silicon-bonded unsaturated groups per molecule; (B) an organohydrogenpolysiloxane containing at least three silicon-bonded hydrogen atoms per molecule; and (C) an ultraviolet-activated hydrosilylation platinum catalyst having, as a ligand, a cyclopentadienyl group to which a condensed aromatic hydrocarbon group is bonded; and the method comprising, in any order, the steps of: (i) bonding the first substrate layer to which the ultraviolet-curable silicone composition has been applied to a second substrate layer via the layer of ultraviolet-curable silicone composition; (ii) subjecting the ultraviolet-curable silicone composition applied to the first substrate layer to a pressure less than atmospheric pressure; and (iii) irradiating the ultraviolet-curable silicone composition applied to the first substrate layer with ultraviolet light.

2. The method according to claim 1, wherein steps (i), (ii), and (iii) are carried out in the order of step (ii), step (iii), and step (i).

3. The method according to claim 1, wherein steps (i), (ii), and (iii) are carried out in the order of step (iii), step (ii), and step (i).

4. The method according to claim 1, wherein step (iii) is a step of irradiating with ultraviolet light having a wavelength of 365 nm or more.

5. The method according to claim 1, wherein component (A) is a linear organopolysiloxane.

6. The method according to claim 1, wherein the unsaturated group of said organopolysiloxane (A) is an alkenyl group.

7. The method according to claim 1, wherein the ratio of the amount of hydrogen directly bonded to silicon contained in (B) to the amount of unsaturated groups contained in (A) (H / Vi ratio) is in the range of 0.2 to 2.

0.

8. The method of claim 1, wherein the ultraviolet-activated platinum hydrosilylation catalyst (C) is [1-methyl-3-(2'-naphthyl)-cyclopentadienyl]trimethylplatinum or [1-methyl-3-(9'-phenanthryl)-cyclopentadienyl]trimethylplatinum.

9. The method according to any one of claims 1 to 8, wherein the first substrate or the second substrate is selected from the group consisting of epoxy resin, polyester resin, polycarbonate resin, acrylic resin, a polarizing plate, and glass.

10. An ultraviolet-curable silicone composition for bonding substrates, comprising: (A) an organopolysiloxane containing at least two silicon-bonded unsaturated groups per molecule; (B) an organohydrogenpolysiloxane containing at least three silicon-bonded hydrogen atoms per molecule; and (C) an ultraviolet-activated hydrosilylation platinum catalyst having, as a ligand, a cyclopentadienyl group to which a condensed aromatic hydrocarbon group is bonded.

11. The ultraviolet-curable silicone composition according to claim 10, wherein the ultraviolet-activated platinum hydrosilylation catalyst (C) is [1-methyl-3-(2'-naphthyl)-cyclopentadienyl]trimethylplatinum or [1-methyl-3-(9'-phenanthryl)-cyclopentadienyl]trimethylplatinum.

12. A member having a layer bonded with the ultraviolet-curable silicone composition according to claim 10 or 11.

13. An ultraviolet-curable silicone composition comprising: (A) an organopolysiloxane containing at least two unsaturated groups bonded to silicon atoms per molecule; (B) an organohydrogenpolysiloxane having at least three hydrogen atoms bonded to silicon atoms per molecule; and (C) an ultraviolet-activated hydrosilylation platinum catalyst having, as a ligand, a cyclopentadienyl group bonded to a condensed aromatic hydrocarbon group; wherein the content of organic solvents that are liquid at room temperature and normal pressure and volatilize under reduced pressure is 0 mass% of the entire composition.

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