Ultraviolet curable silicone composition, cured product, laminate, and method for producing laminate

Abstract

The present invention provides an ultraviolet curable silicone composition which contains the following components (A) to (C): (A) an organopolysiloxane represented by formula (1); (B) an organohydrogen polysiloxane represented by formula (2); and (C) a photoactive hydrosilylation reaction catalyst. Consequently, the present invention provides: an ultraviolet curable silicone composition which is capable of suppressing curing inhibition even in cases where the ultraviolet curable silicone composition is cured on an adherend such as a polarizing plate; a cured product of the silicone composition; a laminate which uses the silicone composition; and a method for producing a laminate.

Description

UV-curable silicone composition, cured product, laminate, and method for producing the laminate

[0001] The present invention relates to an ultraviolet-curable silicone composition, a cured product thereof, a laminate, and a method for producing the laminate.

[0002] Electronic devices with image display capabilities, such as displays and touch panels, generally have a protective cover panel with excellent light transmittance, made of a highly transparent resin such as acrylic or polycarbonate, or glass, and an image display unit that includes a polarizing plate and an image display element on a substrate.

[0003] An optically transparent resin layer is often disposed between the cover panel and the image display unit to improve visibility and mechanical strength.

[0004] For the optically transparent resin layer, a UV-addition-curable transparent organopolysiloxane adhesive composition has been proposed (Patent Document 1). This adhesive composition undergoes a gradual platinum-catalyzed curing reaction upon UV irradiation, making it possible to employ a processing process in which the adhesive composition is applied to a polarizing plate in an image display unit, irradiated with UV light, and then a cover panel is attached. This offers the advantages of enabling use in areas (dark areas) that would not be exposed to UV light using the integrated molding method described above, and of enabling the use of cover panels containing UV absorbers for weather resistance.

[0005] On the other hand, when a polarizing plate and liquid resin are irradiated with UV light while they are in contact with each other, the resin's curing process can be delayed. This is thought to be due to the fact that UV irradiation generates curing inhibitors from the polarizing plate, which act on the hydrogen atoms bonded to silicon atoms, reducing the resin's curing ability or inhibiting the activity of the platinum group metal catalyst. When this occurs, the resin on the polarizing plate does not cure sufficiently, which can lead to concerns about reduced adhesion and bonding strength, which can damage the reliability of the device, and the long curing time of the resin, which can reduce mass productivity.

[0006] In such cases, measures can be taken to ensure curability by adding a temperature-raising process using heating equipment or by extending the time the resin is left to stand until curing. However, excessive heating raises concerns that thermal expansion and contraction can lead to warping of components and resin deterioration, and extending the time the resin is left to stand is a problem that directly leads to a decrease in mass productivity.

[0007] A method has also been proposed in which curing is induced by irradiating light of a specific wavelength to reduce curing inhibition (Patent Document 2). However, changing the wavelength requires the introduction of an irradiation device or the construction of a new production line.

[0008] JP 2015-110752 A JP 2020-158548 A

[0009] The present invention has been made to solve the above problems, and has as its object to provide an ultraviolet-curable silicone composition that can suppress curing inhibition even when cured on an adherend such as a polarizing plate, a cured product of the silicone composition, a laminate using the silicone composition, and a method for producing the laminate.

[0010] In order to solve the above problems, the present invention provides an ultraviolet-curable silicone composition containing the following components (A) to (C): (A) an organopolysiloxane represented by the following formula (1): (In the formula, R １ and R ２ each independently represents a substituted or unsubstituted alkenyl group or a substituted or unsubstituted saturated hydrocarbon group; R １ and R ２ At least one of R is an alkenyl group. ３ each independently represents a substituted or unsubstituted aryl group; R ４ each independently represents a substituted or unsubstituted divalent hydrocarbon group having 1 to 6 carbon atoms, optionally interrupted by an ether bond; k represents a number from 1 to 1000, m represents a number from 1 to 500, and n represents a number from 0 to 300, and the numbers satisfy the relationship m / (k+m+n)=0.01 to 0.5. The units in parentheses may be arranged in any order.) (B) An organohydrogenpolysiloxane represented by the following formula (2): (In the formula, R３ each independently represents a substituted or unsubstituted aryl group; R ５ each independently represents a hydrogen atom or a substituted or unsubstituted saturated hydrocarbon group; R ６ each independently represents a substituted or unsubstituted saturated hydrocarbon group, or a substituted or unsubstituted aryl group. p represents a number from 0 to 200, q represents a number from 0 to 100, and r represents a number from 2 to 200, provided that p+q+r≧15 and r / (p+q+r)≧0.6 are satisfied. The siloxane units in the parentheses may be arranged in any order. (C) Photoactivatable hydrosilylation reaction catalyst.

[0011] The above-mentioned UV-curable liquid silicone composition can be cured in a short time of several minutes to several tens of minutes under mild temperature conditions of 100° C. or less, and it is possible to suppress inhibition of curing caused by substrates such as polarizing plates. In particular, it can be cured in a short time of several minutes to several hours even at room temperature, and the resulting cured product has low hardness, which reduces stress on the substrate.

[0012] The ultraviolet-curable silicone composition of the present invention is characterized in that, in the component (A), R １ one or two of R are substituted or unsubstituted alkenyl groups; ２ is preferably a substituted or unsubstituted alkyl group.

[0013] The silicone composition using such component (A) exhibits excellent physical properties when cured.

[0014] Furthermore, in the UV-curable silicone composition of the present invention, in the component (B), R ５ are each preferably independently a substituted or unsubstituted alkyl group.

[0015] The silicone composition using such component (B) can further suppress inhibition of curing.

[0016] Furthermore, in the UV-curable silicone composition of the present invention, the ratio of the number of moles of hydrogen atoms directly bonded to silicon atoms (Si—H groups) to the number of moles of alkenyl groups directly bonded to silicon atoms in the silicone composition ([number of moles of Si—H groups] / [number of moles of alkenyl groups]) is preferably 0.5 to 3.0.

[0017] The silicone composition having such a molar ratio exhibits excellent curability and excellent physical properties of the cured product.

[0018] In the ultraviolet-curable silicone composition of the present invention, the component (C) is preferably at least one selected from the group consisting of (cyclopentadienyl)dimethyl platinum complex, (methylcyclopentadienyl)diethyl platinum complex, (trimethylsilylcyclopentadienyl)diphenyl platinum complex, (methylcycloocta-1,5-dienyl)diethyl platinum complex, (cyclopentadienyl)trimethyl platinum complex, (cyclopentadienyl)ethyldimethyl platinum complex, (cyclopentadienyl)acetyldimethyl platinum complex, (methylcyclopentadienyl)trimethyl platinum complex, (methylcyclopentadienyl)trihexyl platinum complex, (trimethylsilylcyclopentadienyl)trimethyl platinum complex, (dimethylphenylsilylcyclopentadienyl)trinyl platinum complex, and (cyclopentadienyl)dimethyltrimethylsilylmethyl platinum complex.

[0019] In the silicone composition using such component (C), light irradiation accelerates the hydrosilylation reaction between the silicon-bonded alkenyl groups in component (A) and the Si—H groups in component (B), resulting in superior curability.

[0020] Furthermore, the UV-curable silicone composition of the present invention is preferably one that, after curing at 23° C. for 24 hours after UV irradiation, has a penetration of 10 to 100.

[0021] The silicone composition having a penetration within the above range can adequately hold components together when used in an image display device, and can also reduce stress distortion in the polarizing plate, suppressing light leakage during lighting (the phenomenon in which yellow patterns appear on a white screen when powered on, or white patterns appear on a black screen).

[0022] The present invention provides a cured product of the ultraviolet-curable silicone composition of the present invention.

[0023] Such a cured product exhibits reduced curing inhibition on an adherend such as a polarizing plate, and can be used for bonding, sealing, etc., of optical devices such as image display devices.

[0024] The present invention also provides a laminate comprising a substrate and a cured product of the ultraviolet-curable silicone composition of the present invention laminated together.

[0025] According to the laminate of the present invention, it is possible to provide a laminate with excellent reliability.

[0026] Furthermore, the present invention provides a method for producing a laminate, which includes a coating step of coating the ultraviolet-curable silicone composition of the present invention onto the surface of a first substrate, a lamination step of laminating a second substrate with the coated ultraviolet-curable silicone composition interposed therebetween, an ultraviolet irradiation step of irradiating the coated ultraviolet-curable silicone composition with ultraviolet rays, and a curing step of curing the ultraviolet-irradiated ultraviolet-curable silicone composition at a temperature of 5 to 100°C.

[0027] According to such a method for producing a laminate, it is possible to suppress the stress on the substrate, while suppressing the inhibition of curing caused by the substrate such as a polarizing plate, and to perform bonding of the substrate at a low temperature in a short time.

[0028] In the method for producing a laminate of the present invention, the ultraviolet irradiation step is preferably carried out after the coating step and before the laminating step.

[0029] In the method for producing a laminate of the present invention, the ultraviolet irradiation step is preferably carried out after the coating step and after the laminating step.

[0030] Furthermore, in the method for producing a laminate of the present invention, it is preferable that the curing step is carried out after the ultraviolet irradiation step and before the laminating step.

[0031] In the method for producing a laminate of the present invention, there is a degree of freedom in the timing of the ultraviolet irradiation step, and therefore a wide range of process designs are possible.

[0032] In the method for producing a laminate of the present invention, the first substrate is preferably a polarizing plate or a polarizing film.

[0033] In the method for producing a laminate of the present invention, the second substrate is preferably a polarizing plate or a polarizing film.

[0034] According to such a method for producing a laminate, it is possible to suppress the stress on the substrate, while suppressing the inhibition of curing caused by the substrate such as a polarizing plate, and to perform bonding of the substrate at a low temperature in a short time.

[0035] In the method for producing a laminate of the present invention, it is preferable that the peak wavelength of the ultraviolet light irradiated in the ultraviolet light irradiation step is 300 to 420 nm.

[0036] If the ultraviolet light has such a peak wavelength, the laminate of the present invention can be produced even in equipment equipped with a conventional ultraviolet irradiation device.

[0037] As described above, the UV-curable silicone composition of the present invention can suppress cure inhibition even when cured on an adherend such as a polarizing plate, and therefore can be used for bonding, sealing, etc. of optical devices such as image display devices. Furthermore, the method for producing a laminate of the present invention can suppress stress on the adherend and bond components while suppressing cure inhibition caused by components such as polarizing plates, making it possible to provide, for example, an image display device with good reliability and visibility, and can be used for bonding optical devices and displays, particularly touch panels.

[0038] As described above, there has been a need for the development of an ultraviolet-curable silicone composition that can suppress curing inhibition even when cured on an adherend such as a polarizing plate.

[0039] As a result of extensive research into the above-mentioned problems, the present inventors discovered that an ultraviolet-curable silicone composition containing the following components (A), (B), and (C) can suppress curing inhibition even when cured on an adherend such as a polarizing plate, and thus completed the present invention.

[0040] That is, the present invention provides an ultraviolet-curable silicone composition containing the following components (A) to (C): (A) an organopolysiloxane represented by the following formula (1): (In the formula, R １ and R ２ each independently represents a substituted or unsubstituted alkenyl group or a substituted or unsubstituted saturated hydrocarbon group; R １ and R ２ At least one of R is an alkenyl group. ３ each independently represents a substituted or unsubstituted aryl group; R ４ each independently represents a substituted or unsubstituted divalent hydrocarbon group having 1 to 6 carbon atoms, optionally interrupted by an ether bond; k represents a number from 1 to 1000, m represents a number from 1 to 500, and n represents a number from 0 to 300, and the numbers satisfy the relationship m / (k+m+n)=0.01 to 0.5. The units in parentheses may be arranged in any order.) (B) An organohydrogenpolysiloxane represented by the following formula (2): (In the formula, R ３ each independently represents a substituted or unsubstituted aryl group; R ５ each independently represents a hydrogen atom or a substituted or unsubstituted saturated hydrocarbon group; R ６ each independently represents a substituted or unsubstituted saturated hydrocarbon group, or a substituted or unsubstituted aryl group. p represents a number from 0 to 200, q represents a number from 0 to 100, and r represents a number from 2 to 200, provided that p+q+r≧15 and r / (p+q+r)≧0.6 are satisfied. The siloxane units in the parentheses may be arranged in any order. (C) Photoactivatable hydrosilylation reaction catalyst.

[0041] The present invention will be described in detail below, but the present invention is not limited thereto.

[0042] [UV-Curable Silicone Composition] The UV-curable silicone composition of the present invention contains the following components (A), (B), and (C), and may contain other components as necessary. Each component will be described in detail below.

[0043] [Component (A)] Component (A) is an organopolysiloxane represented by the following formula (1): It has one or more alkenyl groups in each molecule. (In the formula, R １ and R ２ each independently represents a substituted or unsubstituted alkenyl group or a substituted or unsubstituted saturated hydrocarbon group; R １ and R ２ At least one of R is an alkenyl group. ３ each independently represents a substituted or unsubstituted aryl group; R ４ each independently represents a substituted or unsubstituted divalent hydrocarbon group having 1 to 6 carbon atoms, optionally interrupted by an ether bond; k represents a number from 1 to 1000, m represents a number from 1 to 500, and n represents a number from 0 to 300, and the relationship m / (k+m+n)=0.01 to 0.5 is satisfied. The units in parentheses may be arranged in any order.

[0044] In the above formula (1), R １ , R ２ The alkenyl group may be linear, branched, or cyclic, and preferably has 2 to 20 carbon atoms, more preferably 2 to 10 carbon atoms, and even more preferably 2 to 6 carbon atoms. Specific examples of the alkenyl group include vinyl, allyl, butenyl, pentenyl, and hexenyl groups, with vinyl being preferred.

[0045] In addition, some or all of the hydrogen atoms of the alkenyl group may be substituted with halogen atoms such as F, Cl, Br, etc., or with a cyano group.

[0046] In the above formula (1), R １ , R ２The saturated hydrocarbon group may be linear, branched, or cyclic, and preferably has 1 to 20 carbon atoms, more preferably has 1 to 10 carbon atoms, and even more preferably has 1 to 6 carbon atoms.

[0047] Specific examples of the saturated hydrocarbon group include linear or branched alkyl groups such as methyl, ethyl, n-propyl, i-propyl, n-butyl, n-pentyl, n-hexyl, and n-heptyl groups; and cyclic alkyl groups such as cyclohexyl groups, with a methyl group being preferred.

[0048] In addition, some or all of the hydrogen atoms of the saturated hydrocarbon group may be substituted with a halogen atom such as F, Cl, or Br, a cyano group, or the like. Specific examples of such groups include halogen-substituted alkyl groups such as chloromethyl, 3-chloropropyl, and 3,3,3-trifluoropropyl groups.

[0049] In the above formula (1), R １ and R ２ At least one of R is an alkenyl group, and preferably R １ one or two of R are substituted or unsubstituted alkenyl groups, particularly vinyl groups; ２ is a substituted or unsubstituted alkyl group, in particular a methyl group.

[0050] In the above formula (1), R ３ The aryl group preferably has 6 to 20 carbon atoms, more preferably 6 to 10 carbon atoms. Specific examples of the aryl group include phenyl, naphthyl, tolyl, xylyl, and mesityl groups, with the phenyl group being preferred.

[0051] In addition, some or all of the hydrogen atoms of the aryl group may be substituted with halogen atoms such as F, Cl, Br, etc., or with a cyano group, and specific examples of such groups include a chlorophenyl group.

[0052] R ４ Specific examples of the divalent hydrocarbon group include methylene, ethylene, trimethylene, tetramethylene, pentamethylene, and phenylene groups, with the ethylene group being preferred.

[0053] The divalent hydrocarbon group may have an ether bond (—O—) interposed therein, and some or all of the hydrogen atoms of the hydrocarbon group may be substituted with halogen atoms such as F, Cl, or Br, or with cyano groups, etc.

[0054] In the above formula (1), k is a number from 1 to 1000, and preferably a number from 1 to 500. If k is greater than 1000, the viscosity of the organopolysiloxane may become too high.

[0055] In the above formula (1), m is a number from 1 to 500, and preferably a number from 1 to 300. If m is greater than 500, the viscosity of the organopolysiloxane may become too high.

[0056] In the above formula (1), n ​​is a number from 0 to 300, and preferably a number from 0 to 100. If n is greater than 300, heat resistance may decrease. In the above formula (1), m / (k+m+n) is a number that satisfies the relationship m / (k+m+n) = 0.01 to 0.5, and preferably 0.1 to 0.3. If m / (k+m+n) is less than 0.01, the hardness of the cured product may decrease, and if it is greater than 0.5, the viscosity may become too high.

[0057] Specific examples of component (A) include, but are not limited to, organopolysiloxanes represented by the following formulas (3) to (6). Here, Me represents a methyl group, Ph represents a phenyl group, and Vi represents a vinyl group (the same applies hereinafter). In the formulas, the arrangement of the units in parentheses can be random or block.

[0058] (ViMe ２ SiO １／２ ) １．２ (Me ３ SiO １／２ ) ０．８ (Me ２ SiO ２／２ ) ５６ (Ph ２ SiO ２／２ ) １９ (6)

[0059] The organopolysiloxane of component (A) may use either a single compound, or a combination of two or more different compounds.

[0060] [Component (B)] Component (B) is an organohydrogenpolysiloxane represented by the following formula (2): It has two or more hydrogen atoms bonded to silicon atoms (Si—H groups) per molecule. (In the formula, R ３ each independently represents a substituted or unsubstituted aryl group; R ５ each independently represents a hydrogen atom or a substituted or unsubstituted saturated hydrocarbon group; R ６ each independently represents a substituted or unsubstituted saturated hydrocarbon group or a substituted or unsubstituted aryl group. p represents a number from 0 to 200, q represents a number from 0 to 100, and r represents a number from 2 to 200, and these numbers satisfy p+q+r≧15 and r / (p+q+r)≧0.6. The siloxane units in the parentheses may be arranged in any order.

[0061] In the above formula (2), R ３ and R ６ Examples of the aryl group include the same groups as those exemplified for component (A) above, with a phenyl group being preferred.

[0062] In the above formula (2), R ５ and R ６ The saturated hydrocarbon group of R １ and R ２ Examples of the groups include the same groups as those exemplified in the above, and a substituted or unsubstituted alkyl group is preferred, with a methyl group being particularly preferred.

[0063] In the above formula (2), p is a number from 0 to 200, and preferably a number from 0 to 100. If p is greater than 200, the viscosity may become too high.

[0064] In the above formula (2), q is a number from 0 to 100, and preferably a number from 0 to 50. If q is greater than 100, the viscosity may become too high.

[0065] In the above formula (2), r is a number from 2 to 200, and preferably a number from 10 to 150. If r is greater than 200, the viscosity may become too high, and if r is less than 2, the curability may be impaired.

[0066] Furthermore, in the above formula (2), p, q, and r satisfy p+q+r≧15 and r / (p+q+r)≧0.6, and if p+q+r is less than 15 or r / (p+q+r) is less than 0.6, the effect of reducing cure inhibition is impaired.

[0067] Specific examples of component (B) include, but are not limited to, organopolysiloxanes represented by the following formulas (7) to (9), where the arrangement of the siloxane units in parentheses can be random or block.

[0068]

[0069] The organohydrogenpolysiloxane of component (B) may use either a single compound, or a combination of two or more different compounds.

[0070] In the ultraviolet-curable silicone composition of the present invention, the ratio of the number of moles of hydrogen atoms directly bonded to silicon atoms (Si—H groups) to the number of moles of alkenyl groups directly bonded to silicon atoms in the silicone composition ([number of moles of Si—H groups] / [number of moles of alkenyl groups]) is preferably 0.5 to 3.0.

[0071] From the viewpoints of curability and the physical properties of the cured product, the amount of component (B) blended in the ultraviolet-curable silicone composition of the present invention is preferably an amount such that the ratio of the number of moles of hydrogen atoms directly bonded to silicon atoms (Si—H groups) to the number of moles of alkenyl groups directly bonded to silicon atoms in the silicone composition ([number of moles of Si—H groups] / [number of moles of alkenyl groups]) is 0.5 to 3.0, and more preferably an amount 0.7 to 1.5.

[0072] [Component (C)] Component (C) is a photoactivatable hydrosilylation catalyst.

[0073] Component (C) is inactive when shielded from light, but is activated when irradiated with light having a wavelength of 300 to 420 nm, for example, and exhibits catalytic action that promotes the hydrosilylation reaction between the silicon-bonded alkenyl groups in component (A) and the Si—H groups in component (B).

[0074] Specific examples of the component (C) include (cyclopentadienyl)dimethyl platinum complex, (methylcyclopentadienyl)diethyl platinum complex, (trimethylsilylcyclopentadienyl)diphenyl platinum complex, (methylcycloocta-1,5-dienyl)diethyl platinum complex, (cyclopentadienyl)trimethyl platinum complex, (cyclopentadienyl)ethyldimethyl platinum complex, (cyclopentadienyl)acetyldimethyl platinum complex, (methylcyclopentadienyl)trimethyl platinum complex, (methylcyclopentadienyl)trihexyl platinum complex, (trimethylsilylcyclopentadienyl)trimethyl platinum complex, (dimethylphenylsilylcyclopentadienyl)trinyl platinum complex, and (cyclopentadienyl)dimethyltrimethylsilylmethyl platinum complex. These may be used alone or in combination of two or more.

[0075] There are no particular restrictions on the amount of component (C) contained, so long as it is an amount that promotes the curing (hydrosilylation reaction) of the ultraviolet-curable silicone composition of the present invention. However, an amount that is calculated as the mass of the metal relative to component (A) is preferably in the range of 0.01 to 500 ppm, more preferably in the range of 0.05 to 100 ppm, and even more preferably in the range of 0.01 to 50 ppm.

[0076] [Component (D)] If necessary, an adhesion aid may be added as component (D) to the UV-curable silicone composition of the present invention to impart adhesion to substrates such as polarizing plates, glass, polycarbonate resins, and acrylic resins.

[0077] Specific examples of the adhesion promoter containing a siloxane bond among the component (D) include vinyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-1003), 7-octenyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-1083), γ-(glycidyloxypropyl)trimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-403), γ-(methacryloxypropyl)trimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-503), 3-trimethoxysilylpropylsuccinic anhydride (manufactured by Shin-Etsu Chemical Co., Ltd., X-12-967C), and hydrolysates thereof, as well as compounds represented by the following structural formula:

[0078]

[0079] Specific examples of the adhesion promoter that does not contain a siloxane bond among the component (D) include allyl glycidyl ether, vinylcyclohexene monoxide, diethyl 2-allylmalonate, diallyl bisphenol ether, allyl benzoate, diallyl phthalate, pyromellitic acid tetraallyl ester (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., TRIAM 805), triallyl isocyanurate, etc. The component (D) may be used alone or in combination of two or more.

[0080] When component (D) is used, the amount added is preferably 0.05 to 10 parts by mass, and more preferably 0.05 to 5 parts by mass, per 100 parts by mass of component (A). When the amount of component (D) is within the above range, appropriate adhesiveness can be imparted.

[0081] [Component (E)] If necessary, a reaction inhibitor (E) may be added to the UV-curable silicone composition of the present invention for the purpose of controlling the reactivity of the hydrosilylation reaction catalyst so as to prevent thickening or gelation during preparation of the composition or before heat curing when the composition is applied to a substrate.

[0082] Specific examples of the reaction inhibitor include 3-methyl-1-butyn-3-ol, 3-methyl-1-pentyn-3-ol, 3,5-dimethyl-1-hexyn-3-ol, 1-ethynylcyclohexanol, ethynylmethyldecylcarbinol, 3-methyl-3-trimethylsiloxy-1-butyne, 3-methyl-3-trimethylsiloxy-1-pentyne, 3,5-dimethyl-3-trimethylsiloxy-1-hexyne, 1-ethynyl-1-trimethylsiloxycyclohexane, bis(2,2-dimethyl-3-butynoxy)dimethylsilane, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, and 1,1,3,3-tetramethyl-1,3-divinyldisiloxane. These may be used alone or in combination of two or more.

[0083] Among these, 1-ethynylcyclohexanol, ethynylmethyldecylcarbinol, 3-methyl-1-butyn-3-ol, and bis(2,2-dimethyl-3-butynoxy)dimethylsilane are preferred.

[0084] When component (E) is used, the blending amount thereof is preferably 0.01 to 2.0 parts by mass, and more preferably 0.01 to 0.1 parts by mass, per 100 parts by mass of component (A).Within this range, the reaction control effect is sufficiently exhibited.

[0085] [Other Components] In addition to the components (A) to (E) described above, the UV-curable silicone composition of the present invention may also contain other components, such as those exemplified below.

[0086] Other components include, for example, thixotropy control agents such as fumed silica; reinforcing agents such as crystalline silica; antioxidants; light stabilizers; heat resistance improvers such as metal oxides and metal hydroxides; colorants such as titanium oxide; thermal conductivity imparting fillers such as alumina and crystalline silica; viscosity adjusters such as non-reactive organopolysiloxanes that do not have reactive functional groups; conductivity imparting agents such as metal powders of silver, gold, etc.; and organic solvents such as toluene, xylene, hexane, and ethyl acetate.

[0087] The ultraviolet-curable silicone composition of the present invention can be prepared by mixing the above-mentioned components (A) to (C), the optional components (D) and (E), and other components using a known method.

[0088] The viscosity of the UV-curable silicone composition of the present invention at 25°C is preferably 10 to 120,000 mPa·s, and more preferably 1,000 to 50,000 mPa·s. Within this range, the composition has excellent coatability and can maintain a consistent film thickness on the substrate. In this specification, viscosity is measured at 25°C using a rotational viscometer.

[0089] The ultraviolet-curable silicone composition of the present invention can be cured, for example, by irradiating the silicone composition with ultraviolet light and then curing it at 40°C or less, or by irradiating the silicone composition with ultraviolet light and then curing it at 100°C or less for 30 minutes or less.

[0090] UV sources useful for curing the UV-curable silicone composition of the present invention include conventional mercury vapor lamps, metal halide lamps, and light-emitting diode (LED) elements designed to emit UV energy in various UV wavelength bands. For example, a useful UV wavelength range is 300 to 420 nm, preferably 340 to 410 nm. The UV irradiation dose useful for curing is not particularly limited as long as it is sufficient for curing, but is preferably 100 to 30,000 mJ / cm. ２ and more preferably 1,000 to 10,000 mJ / cm ２ and more preferably 1,500 to 7,500 mJ / cm ２ is.

[0091] The method for curing the UV-curable silicone composition of the present invention allows for curing in a short time of a few minutes to a few hours even at low temperatures of 100°C or less, particularly at room temperature, and therefore can be used for heat-sensitive materials such as resin substrates.

[0092] The UV-curable silicone composition of the present invention preferably has a needle penetration after curing at 23° C. for 24 hours following UV irradiation of 10 to 100. The needle penetration is measured in accordance with JIS K 6249:2003.

[0093] When the penetration is within the above range, the components can be sufficiently held when used in an image display device, and the stress distortion of the polarizing plate can be reduced, thereby suppressing light leakage when the display is turned on (the phenomenon in which a yellow pattern appears on a white screen when powered on, or the phenomenon in which a white pattern appears on a black screen).

[0094] [Laminate] The laminate of the present invention is a laminate of a substrate and a cured product of the ultraviolet-curable silicone composition of the present invention.

[0095] Examples of the substrate include polarizing materials and composite materials, metal members, plastic members, and ceramic members. The substrate is particularly useful for casings for electrical, electronic, and optical applications, as well as for coating, casting, bonding, and sealing of members, and is particularly useful for polarizing plates and polarizing films.

[0096] The UV-curable silicone composition of the present invention can also be used on substrates that have been activated by known pretreatment processes such as primer treatment, plasma treatment, and excimer light treatment.

[0097] [Method for Producing Laminate] The method for producing a laminate of the present invention comprises a coating step of coating the ultraviolet-curable silicone composition of the present invention onto the surface of a first substrate, a lamination step of laminating a second substrate via the coated ultraviolet-curable silicone composition, an ultraviolet irradiation step of irradiating the coated ultraviolet-curable silicone composition with ultraviolet rays, and a curing step of curing the ultraviolet-irradiated ultraviolet-curable silicone composition at a temperature of 5 to 100°C.

[0098] [Coating Step] The coating step in the method for producing a laminate of the present invention is a step of coating the ultraviolet-curable silicone composition of the present invention onto the surface of a first substrate.

[0099] Examples of the coating method in the coating step include coating using a slit coater, a DAM-Fill method, and a fishbone method.

[0100] The amount of coating in the coating step is not particularly limited, but it is preferable that the amount be such that the thickness of the silicone layer after curing is 100 to 5,000 μm.

[0101] [Ultraviolet Light Irradiation Step] The ultraviolet light irradiation step in the method for producing a laminate of the present invention is a step in which the applied ultraviolet-curable silicone composition of the present invention is irradiated with ultraviolet light.

[0102] The ultraviolet irradiation method in the ultraviolet irradiation step includes a method of irradiating an appropriate amount of ultraviolet light using a lamp with a peak wavelength of 300 to 420 nm as a light source, etc. A 365 nm UV-LED lamp is preferred as the ultraviolet light source.

[0103] The peak wavelength of the ultraviolet light irradiated in the ultraviolet light irradiation step is preferably 300 to 420 nm, more preferably 340 to 410 nm, and even more preferably 365 nm.

[0104] The temperature during ultraviolet irradiation in the ultraviolet irradiation step is preferably 5 to 60°C, more preferably 5 to 35°C, from the viewpoints of curing speed and prevention of discoloration.

[0105] The irradiation intensity in the ultraviolet irradiation step is 300 to 2,000 mW / cm 2 The irradiation dose is preferably 100 to 30,000 mJ / cm from the viewpoint of curability and workability. 2 and more preferably 1,000 to 10,000 mJ / cm ２ and more preferably 1,500 to 7,500 mJ / cm ２ is.

[0106] In the ultraviolet irradiation step, the ultraviolet light may be irradiated so as to be transmitted through the substrate.

[0107] [Laminating Step] The laminating step in the method for producing a laminate of the present invention is a step of laminating a second substrate on a layer of the ultraviolet-curable silicone composition of the present invention or a cured product thereof to form a laminate in which the two substrates are laminated together via the ultraviolet-curable silicone composition of the present invention or a cured product thereof.

[0108] Examples of lamination methods in the laminating step include placing a semi-solid cured material layer-substrate laminate that has been through the coating step, UV irradiation step, and curing step, or the UV-curable silicone composition after the coating step, or the UV-curable silicone composition layer-substrate laminate that has been through the coating step and UV irradiation step, in a vacuum or atmospheric pressure laminating device, and laminating and laminating a second substrate on the UV-curable silicone composition or its cured material layer, and in the case of an uncured composition, carrying out the remaining steps to cure it and form a laminate.

[0109] [Curing Step] The curing step in the method for producing a laminate of the present invention is a step in which the ultraviolet-curable silicone composition of the present invention that has been irradiated with ultraviolet light is cured at 5 to 100°C.

[0110] The curing temperature in the curing step is 5 to 100°C, preferably 5 to 60°C, and more preferably 5 to 35°C, from the viewpoint of suppressing warping and deterioration due to thermal expansion / contraction of the laminate.

[0111] The curing atmosphere in the curing step is not particularly limited, but is preferably an air atmosphere.

[0112] The curing time in the curing step is not particularly limited, but is preferably about 1 minute to 24 hours.

[0113] In the method for producing a laminate of the present invention, the ultraviolet irradiation step may be performed after the coating step and before the lamination step, and in this case, the curing step may be performed after the ultraviolet irradiation step and before the lamination step. Also, in the method for producing a laminate of the present invention, the ultraviolet irradiation step may be performed after the coating step and after the lamination step.

[0114] In the method for producing a laminate of the present invention, the first substrate may be a polarizing plate or a polarizing film, and the second substrate may be a polarizing plate or a polarizing film.

[0115] According to the laminate manufacturing method of the present invention, it is possible to suppress the stress on the substrate, while suppressing the inhibition of curing caused by the substrate such as a polarizing plate, and to perform the bonding of the substrate at a low temperature in a short time. Furthermore, the laminate manufacturing method of the present invention has a degree of freedom in the timing of the ultraviolet irradiation step, and therefore a wide range of process designs can be made to suit the structure of the device to be manufactured, such as a flat display or a curved display.

[0116] EXAMPLES The present invention will be specifically explained below using examples and comparative examples, but the present invention is not limited to these.

[0117] Examples 1 to 4, Comparative Examples 1 and 2 UV-curable silicone compositions were prepared by mixing the components shown below in the amounts (parts by mass) shown in Table 1. In the following examples, Me represents a methyl group, Ph represents a phenyl group, and Vi represents a vinyl group. Viscosity values ​​were measured at 25°C using a rotational viscometer.

[0118] Component (A): (A-1): Organopolysiloxane represented by the following formula (5): (In the formula, the arrangement order of the units in parentheses is random or block.) (A-2) Organopolysiloxane represented by the following formula (4): (In the formula, the arrangement order of the units in the parentheses is random or block.) (A-3) Organopolysiloxane having an average structure represented by the following formula (6) (ViMe ２ SiO １／２ ) １．２ (Me ３ SiO １／２ ) ０．８ (Me ２ SiO ２／２ ) ５６ (Ph ２ SiO ２／２ ) １９ (6)

[0119] Component (B): (B-1): Organohydrogenpolysiloxane represented by the following formula (7): (In the formula, the arrangement order of the units in parentheses is random or block.) (B-2): Organohydrogenpolysiloxane represented by the following formula (8): (In the formula, the arrangement order of the units in parentheses is random or block.) (B-3): Organohydrogenpolysiloxane represented by the following formula (9): (In the formula, the arrangement order of the units in parentheses is random or block.) (B'-4): Organohydrogenpolysiloxane represented by the following formula (10): (In the formula, the arrangement order of the units in the parentheses is random or block, and p+q+r is not 15 or greater.) (B'-5): Organohydrogenpolysiloxane represented by the following formula (11): (In the formula, the arrangement order of the units in the parentheses is random or block. r / p+q+r=0.41, and r / p+q+r≧0.6 is not satisfied.)

[0120] Component (C): (C-1): Solution of (methylcyclopentadienyl)trimethylplatinum complex in polysiloxane (viscosity 1500 mPa·s, 0.5% by mass) in which one molecular chain average terminal is blocked with dimethylvinylsiloxy groups.

[0121] Component (D): (D-1): A compound represented by the following structural formula (12) (D-2): 7-octenyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-1083)

[0122] Component (E): (E-1) 1.0 mass% solution of bis(2,2-dimethyl-3-butynoxy)dimethylsilane, an average of one end of which is blocked with a dimethylvinylsiloxy group (viscosity 1500 mPa·s)

[0123]

[0124] The UV-curable silicone compositions prepared in Examples 1 to 4 and Comparative Examples 1 and 2 were evaluated for hardness (penetration) and gel time of the cured products using the methods described below. The results are shown in Tables 2 and 3.

[0125] [Hardness (penetration) of the cured product] A glass petri dish was filled with the prepared ultraviolet-curable silicone composition to a depth of 1 cm, and a UV-LED lamp (manufactured by Panasonic Corporation, ANOJ6186) with a peak wavelength of 365 nm was used to illuminate the cured product at 100 mW / cm 2 The cumulative light intensity is 3,000 mJ / cm 2 After irradiating the sample so as to obtain a value of 0.1 mm, the sample was cured at 23° C. for 24 hours, and the needle penetration of the cured sample was measured in accordance with JIS K 6249:2003.

[0126] [Gelation Time] The gelation time was measured using an ARES-G2 viscoelasticity measuring device (manufactured by TA Instruments Japan Co., Ltd.) equipped with a UV curing accessory. 1 ml of each prepared UV-curable silicone composition was applied to a stainless steel plate or to one of the polarizing plates described below fixed on the plate, and the gelation time was measured using a UV-LED lamp (manufactured by Panasonic Corporation, ANOJ6186) with a peak wavelength of 365 nm at 100 mW / cm. 2 The cumulative light intensity is 3,000 mJ / cm 2 Each ultraviolet-curable silicone composition was irradiated at the temperature shown in Table 2 so that the viscoelasticity was measured while maintaining the temperature shown in Table 2. The time (seconds) required from the start of UV irradiation until tan δ reached 1 was taken as the gelation time.

[0127] The gelation time was measured while heating at the indicated temperatures so that the gelation time of Comparative Example 1 was within 3,600 seconds. At this time, the gelation times of Comparative Example 1 on Polarizing Plate 2 and Polarizing Plate 3 were longer than the gelation time on Polarizing Plate 1, so it can be said that Polarizing Plates 2 and 3 exhibited a stronger degree of curing inhibition than Polarizing Plate 1.

[0128] Polarizing plate 1: NPF-CWQ1463VCU manufactured by Nitto Denko Corporation Polarizing plate 2: NAZ-EFCWQVAG150 manufactured by Nitto Denko Corporation Polarizing plate 3: NPF-SWQ1423CUARC380 manufactured by Nitto Denko Corporation

[0129] Table 3 also shows the gelation time ratio, expressed by the following formula, when Comparative Example 1 is set as the standard (100): (Gelation time of each Example or Comparative Example) / (Gelation time of Comparative Example 1)×100 (unit: %).

[0130]

[0131] *Gelation time ratio: The gelation time ratio expressed by the following formula, with Comparative Example 1 set as the standard (100): (Gelation time of each Example or Comparative Example) / (Gelation time of Comparative Example 1) x 100 (unit: %)

[0132] As shown in Tables 2 and 3, Examples 1 to 4, which used the UV-curable silicone composition of the present invention, cured rapidly on a polarizing plate. In Example 1, the gelation time ratio was only 1% different from Comparative Example 1 when no polarizing plate was present, but cured 17% faster on Polarizing Plate 1. In Examples 2 to 4, the gelation time ratio was only 8-13% different from Comparative Example 1 when no polarizing plate was present, but cured 27-32% faster on Polarizing Plate 1. Furthermore, on Polarizing Plate 2, which had a strong degree of curing inhibition, curing was 44-48% faster, and on Polarizing Plate 3, curing was 57-58% faster. On the other hand, in Comparative Example 2, the gelation time ratio when no polarizing plate was present was 321% slower than Comparative Example 1, and the composition did not cure on Polarizing Plates 1 to 3, indicating that it was strongly affected by curing inhibition.

[0133] From the above, it was found that the ultraviolet-curable silicone composition of the present invention can reduce the degree of cure inhibition even when cured on an adherend such as a polarizing plate, and therefore can be used for bonding, sealing, etc. of optical devices such as image display devices. Furthermore, it was found that the method for producing a laminate of the present invention can reduce stress on the adherend and bond components while suppressing cure inhibition caused by components such as polarizing plates, making it possible to provide, for example, an image display device with good reliability and visibility, and can be used for bonding optical devices and displays, particularly touch panels.

[0134] This specification includes the following aspects: [1]: An ultraviolet-curable silicone composition comprising the following components (A) to (C): (A) an organopolysiloxane represented by the following formula (1): (In the formula, R １ and R ２ each independently represents a substituted or unsubstituted alkenyl group or a substituted or unsubstituted saturated hydrocarbon group; R １ and R ２ At least one of R is an alkenyl group. ３ each independently represents a substituted or unsubstituted aryl group; R ４ each independently represents a substituted or unsubstituted divalent hydrocarbon group having 1 to 6 carbon atoms, optionally interrupted by an ether bond; k represents a number from 1 to 1000, m represents a number from 1 to 500, and n represents a number from 0 to 300, and the numbers satisfy the relationship m / (k+m+n)=0.01 to 0.5. The units in parentheses may be arranged in any order.) (B) An organohydrogenpolysiloxane represented by the following formula (2): (In the formula, R ３ each independently represents a substituted or unsubstituted aryl group; R ５ each independently represents a hydrogen atom or a substituted or unsubstituted saturated hydrocarbon group; R ６each independently represents a substituted or unsubstituted saturated hydrocarbon group, or a substituted or unsubstituted aryl group. p represents a number from 0 to 200, q represents a number from 0 to 100, and r represents a number from 2 to 200, and these numbers satisfy p+q+r≧15 and r / (p+q+r)≧0.6. The siloxane units in the parentheses may be arranged in any order. (C) Photoactivatable hydrosilylation reaction catalyst. [2]: In the above component (A), R １ one or two of R are substituted or unsubstituted alkenyl groups; ２ [3]: In the component (B), R ５are each independently a substituted or unsubstituted alkyl group. [4]: ​​The ultraviolet-curable silicone composition according to any one of [1], [2], or [3] above, characterized in that the ratio of the number of moles of hydrogen atoms directly bonded to silicon atoms (Si—H groups) to the number of moles of alkenyl groups directly bonded to silicon atoms in the silicone composition ([number of moles of Si—H groups] / [number of moles of alkenyl groups]) is 0.5 to 3.0. [5]: The ultraviolet-curable silicone composition according to any one of [1] to [4] above, wherein component (C) is at least one member selected from the group consisting of a (cyclopentadienyl)dimethyl platinum complex, a (methylcyclopentadienyl)diethyl platinum complex, a (trimethylsilylcyclopentadienyl)diphenyl platinum complex, a (methylcycloocta-1,5-dienyl)diethyl platinum complex, a (cyclopentadienyl)trimethyl platinum complex, a (cyclopentadienyl)ethyldimethyl platinum complex, a (cyclopentadienyl)acetyldimethyl platinum complex, a (methylcyclopentadienyl)trimethyl platinum complex, a (methylcyclopentadienyl)trihexyl platinum complex, a (trimethylsilylcyclopentadienyl)trimethyl platinum complex, a (dimethylphenylsilylcyclopentadienyl)trinyl platinum complex, and a (cyclopentadienyl)dimethyltrimethylsilylmethyl platinum complex. [6]: The ultraviolet-curable silicone composition according to any one of [1] to [5] above, characterized in that after ultraviolet irradiation and curing at 23°C for 24 hours, the needle penetration after curing is 10 to 100. [7]: A cured product of the ultraviolet-curable silicone composition according to any one of [1] to [6] above. [8]: A laminate characterized in that a substrate and a cured product of the ultraviolet-curable silicone composition according to [7] above are laminated together.[9]: A method for producing a laminate, comprising: a coating step of coating the ultraviolet-curable silicone composition according to any one of [1] to [6] above onto the surface of a first substrate; a laminating step of laminating a second substrate via the coated ultraviolet-curable silicone composition; an ultraviolet irradiation step of irradiating the coated ultraviolet-curable silicone composition with ultraviolet light; and a curing step of curing the ultraviolet-irradiated ultraviolet-curable silicone composition at 5 to 100°C.

[10] : A method for producing a laminate according to [9] above, wherein the ultraviolet irradiation step is carried out after the coating step and before the laminating step.

[11] : A method for producing a laminate according to [9] above, wherein the ultraviolet irradiation step is carried out after the coating step and after the laminating step.

[12] : A method for producing a laminate according to

[10] above, wherein the curing step is carried out after the ultraviolet irradiation step and before the laminating step.

[13] : A method for producing a laminate according to any one of [9] to

[12] above, wherein the first substrate is a polarizing plate or a polarizing film.

[14] : The method for producing a laminate according to any one of [9] to

[13] , wherein the second substrate is a polarizing plate or a polarizing film.

[15] : The method for producing a laminate according to any one of [9] to

[14] , wherein the peak wavelength of the ultraviolet light irradiated in the ultraviolet light irradiation step is 300 to 420 nm.

[0135] The present invention is not limited to the above-described embodiments. The above-described embodiments are merely examples, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits similar effects is included within the technical scope of the present invention.

Claims

1. An ultraviolet-curable silicone composition comprising the following components (A) to (C): (A) an organopolysiloxane represented by the following formula (1): (In the formula, R １ and R ２ each independently represents a substituted or unsubstituted alkenyl group or a substituted or unsubstituted saturated hydrocarbon group; R １ and R ２ At least one of R is an alkenyl group. ３ each independently represents a substituted or unsubstituted aryl group; R ４ each independently represents a substituted or unsubstituted divalent hydrocarbon group having 1 to 6 carbon atoms, optionally interrupted by an ether bond; k represents a number from 1 to 1000, m represents a number from 1 to 500, and n represents a number from 0 to 300, and the numbers satisfy the relationship m / (k+m+n)=0.01 to 0.

5. The units in parentheses may be arranged in any order.) (B) An organohydrogenpolysiloxane represented by the following formula (2): (In the formula, R ３ each independently represents a substituted or unsubstituted aryl group; R ５ each independently represents a hydrogen atom or a substituted or unsubstituted saturated hydrocarbon group; R ６ each independently represents a substituted or unsubstituted saturated hydrocarbon group, or a substituted or unsubstituted aryl group. p represents a number from 0 to 200, q represents a number from 0 to 100, and r represents a number from 2 to 200, provided that p+q+r≧15 and r / (p+q+r)≧0.6 are satisfied. The siloxane units in the parentheses may be arranged in any order. (C) Photoactivatable hydrosilylation reaction catalyst.

2. In the component (A), R １ one or two of R are substituted or unsubstituted alkenyl groups; ２ 2. The ultraviolet-curable silicone composition according to claim 1, wherein is a substituted or unsubstituted alkyl group.

3. In the component (B), R ５ 2. The ultraviolet-curable silicone composition according to claim 1, wherein each of the groups independently represents a substituted or unsubstituted alkyl group.

4. The ultraviolet-curable silicone composition according to claim 1, wherein the ratio of the number of moles of hydrogen atoms directly bonded to silicon atoms (Si-H groups) to the number of moles of alkenyl groups directly bonded to silicon atoms in the silicone composition ([number of moles of Si-H groups] / [number of moles of alkenyl groups]) is 0.5 to 3.

0.

5. The ultraviolet-curable silicone composition according to claim 1, wherein component (C) is at least one selected from the group consisting of (cyclopentadienyl)dimethyl platinum complex, (methylcyclopentadienyl)diethyl platinum complex, (trimethylsilylcyclopentadienyl)diphenyl platinum complex, (methylcycloocta-1,5-dienyl)diethyl platinum complex, (cyclopentadienyl)trimethyl platinum complex, (cyclopentadienyl)ethyldimethyl platinum complex, (cyclopentadienyl)acetyldimethyl platinum complex, (methylcyclopentadienyl)trimethyl platinum complex, (methylcyclopentadienyl)trihexyl platinum complex, (trimethylsilylcyclopentadienyl)trimethyl platinum complex, (dimethylphenylsilylcyclopentadienyl)trinyl platinum complex, and (cyclopentadienyl)dimethyltrimethylsilylmethyl platinum complex.

6. The ultraviolet-curable silicone composition according to claim 1, which has a needle penetration of 10 to 100 after curing at 23°C for 24 hours after ultraviolet irradiation.

7. A cured product of the ultraviolet-curable silicone composition according to any one of claims 1 to 6.

8. A laminate comprising a substrate and a cured product of the ultraviolet-curable silicone composition according to claim 7 laminated together.

9. A method for producing a laminate, comprising: a coating step of coating the ultraviolet-curable silicone composition according to any one of claims 1 to 6 onto the surface of a first substrate; a lamination step of laminating a second substrate via the coated ultraviolet-curable silicone composition; an ultraviolet irradiation step of irradiating the coated ultraviolet-curable silicone composition with ultraviolet light; and a curing step of curing the ultraviolet-irradiated ultraviolet-curable silicone composition at a temperature of 5 to 100°C.

10. The method for producing a laminate according to claim 9, wherein the ultraviolet irradiation step is carried out after the coating step and before the laminating step.

11. The method for producing a laminate according to claim 9, wherein the ultraviolet irradiation step is carried out after the coating step and after the laminating step.

12. The method for producing a laminate according to claim 10, wherein the curing step is carried out after the ultraviolet irradiation step and before the laminating step.

13. The method for producing a laminate according to claim 9, wherein the first substrate is a polarizing plate or a polarizing film.

14. The method for producing a laminate according to claim 9, wherein the second substrate is a polarizing plate or a polarizing film.

15. The method for producing a laminate according to claim 9, wherein the peak wavelength of the ultraviolet light irradiated in the ultraviolet light irradiation step is 300 to 420 nm.

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