Antisulfuration agent, article, and method for preventing sulfuration

Abstract

To provide a sulfurization-inhibiting agent comprising an ultraviolet ray-curable organopolysiloxane composition containing an ultraviolet ray-curable organopolysiloxane that does not need a plenty of energy for curing, and giving a cured product exhibiting excellent barrier property to a corrosive gas such as a hydrogen sulfide gas.SOLUTION: A sulfurization-inhibiting agent comprises an ultraviolet-curable organopolysiloxane composition containing an ultraviolet ray-curable organopolysiloxane represented by a general formula (1). In the formula, R1 is independently an unsubstituted, or substituted 1-10C univalent hydrocarbon group, a hydroxyl group, an alkoxy group, or a univalent photodimerization functional group, and at least three R1 in the R1 are univalent photodimerization functional groups. a is an integer of two or more, b, c, and d are each integer of 0 or more, b+c+d is an integer of four or more, and a+b+c+d is an integer of six or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an ultraviolet-curable organopolysiloxane composition containing, as a main component, an ultraviolet-curable organopolysiloxane, in particular an ultraviolet-curable organopolysiloxane having a specific photodimerizable functional group such as a coumarin structure-containing group and requiring little energy for curing, and which is capable of giving a cured product (silicone rubber cured product) that exhibits excellent barrier properties against corrosive gases such as hydrogen sulfide gas; an article having a cured product layer of the sulfurization inhibitor; and a method for preventing the sulfurization of an article. [Background technology]

[0002] Cured products of organopolysiloxane compositions (especially cured silicone rubber products) have excellent electrical properties (electrical insulation), heat resistance, and cold resistance, and are therefore used in a wide range of applications, including electrical and electronic fields and construction. One method for curing these organopolysiloxane compositions is to use light, such as ultraviolet light. Photocurable (UV-curable) organopolysiloxane compositions are characterized by their energy-saving and high productivity. In particular, in the electrical and electronic fields, they are used as coating agents for liquid crystal displays and power circuit boards due to their adhesive and coating suitability for the substrates (resin-based) they are used on. However, while cured products of coating agents made from photocurable organopolysiloxane compositions (especially cured silicone rubber products) satisfy their primary objectives of insulating electrical and electronic circuits and providing moisture protection, they have little or no corrosion protection against corrosive gases such as hydrogen sulfide. These cured products of photocurable organopolysiloxane compositions (cured silicone rubber products) generally have high gas permeability, allowing sulfurous corrosive gases, specifically low-molecular-weight gases such as hydrogen sulfide and sulfur dioxide, to easily pass through, and the sulfurous corrosive gases react with the underlying substrate coated with a film of the cured product of the photocurable organopolysiloxane composition (cured silicone rubber product).When the sulfurous corrosive gases react with the underlying substrate to form sulfides, the electrical and electronic products may lose their properties.

[0003] The following have been exemplified in the past as organopolysiloxane compositions having anti-sulfuration properties in cured products, or as siloxanes containing photodimerizable functional groups.

[0004] Japanese Patent No. 4186071 (Patent Document 1) discloses a room-temperature-curable organopolysiloxane composition in which 0.1% by mass or more but less than 20% by mass of a metal powder, preferably copper powder and / or brass powder, that is sulfurized by sulfur and / or sulfur gas is added to the organopolysiloxane composition. These metals are highly reactive with sulfur and / or sulfur gas, and adding trace amounts to a room-temperature-curable organopolysiloxane composition can impart sulfuration prevention properties to the cured product. However, although the metal powder prevents sulfurization by trapping sulfur-containing gases, this function is lost once all of the metal powder has trapped the sulfur-containing gases.

[0005] Furthermore, Japanese Patent Application Laid-Open No. 2021-165363 (Patent Document 2) discloses an addition-curable silicone resin composition that provides a cured product with excellent thermal shock resistance and sulfurization resistance. It uses an organopolysiloxane containing a phenyl group, and is disclosed as an LED encapsulant that is less likely to peel from the package or crack due to thermal shock. This invention has the problem that heating is required to cure the silicone resin composition, which requires a lot of energy.

[0006] Japanese Patent Laid-Open Publication No. 2014-098080 (Patent Document 3) discloses a photodimerization functional group-containing organopolysiloxane, an active energy ray-curable organopolysiloxane composition containing the same, and a cured product thereof. The base organopolysiloxane component has an average of three photodimerization functional groups, and the publication describes an active energy ray-curable organopolysiloxane composition containing various photodimerizable photodimerization functional group-containing organopolysiloxanes. However, although it states that the composition "cures rapidly upon irradiation with active energy rays such as ultraviolet rays," there is no mention of its sulfurization prevention performance, and the publication simply describes the production of a composition using a photodimerization functional group-containing siloxane. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 4186071 [Patent Document 2] Japanese Patent Publication No. 2021-165363 [Patent Document 3] Japanese Patent Application Laid-Open No. 2014-098080 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention has been made in view of the above circumstances, and has as its object to provide a sulfurization inhibitor comprising an ultraviolet-curable organopolysiloxane composition that contains as a main component an ultraviolet-curable organopolysiloxane that does not require a large amount of energy for curing and that is capable of giving a cured product (silicone rubber cured product) that exhibits excellent barrier properties against corrosive gases such as hydrogen sulfide gas; an article having a cured product layer of the sulfurization inhibitor; and a method for preventing sulfurization of an article. [Means for solving the problem]

[0009] As a result of extensive research conducted by the present inventors in order to achieve the above-mentioned object, they discovered that the above-mentioned requirements can be satisfied by using as a sulfurization inhibitor an ultraviolet-curable organopolysiloxane composition comprising, as a base compound, a linear or branched organopolysiloxane compound having a main chain composed of repeating organosiloxane units, the main chain of which comprises, as needed, a photosensitizer, an organic solvent, and the like, and which has, on average, three or more photodimerizable functional groups, such as coumarin-containing groups, per molecule as monovalent substituents bonded to silicon atoms at the molecular chain terminals and / or in the side chains. This finding led to the completion of the present invention.

[0010] That is, the present invention provides the following sulfurization inhibitor, an article having a cured layer of the sulfurization inhibitor, and a method for preventing sulfurization of the article. [1] A sulfuration inhibitor comprising an ultraviolet-curable organopolysiloxane composition containing an ultraviolet-curable organopolysiloxane represented by the following general formula (1): [ka] (In the formula, R 1 are independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, a hydroxyl group, an alkoxy group, or The following general formula (2) [ka] (In the formula, e is an integer of 1 to 10, and f is 0 or 1.) A coumarin structure-containing group represented by and R 1 On average, at least three of A coumarin structure-containing group represented by the above general formula (2) a is an integer of 2 or more, b, c, and d are each an integer of 0 or more, b+c+d is an integer of 4 or more, and a+b+c+d is an integer of 6 or more. However, (R 1 SiO 3 / 2 ) units of R 1 is two R 1 may be bonded to each other to form an alkylene group.) [2] In general formula (1), R 1 On average, at least four of A coumarin structure-containing group represented by the above general formula (2) The sulfuration inhibitor according to [1], [ 3 ] The ultraviolet-curable organopolysiloxane composition contains 100 parts by mass of an ultraviolet-curable organopolysiloxane represented by general formula (1), 0.001 to 10 parts by mass of a photosensitizer, and / or 0.1 to 100 parts by mass of an organic solvent. [1] or [ 2 10. The sulfuration inhibitor according to any one of claims 1 to 9. [ 4 ] [1]~[ 3 10. An article having a cured product layer of the sulfurization inhibitor according to any one of claims 1 to 9. [ 5 ] At least a part or all of the surface of the article is provided with [1] to [ 3and irradiating the sulfuration inhibitor with ultraviolet light to form a cured layer of the sulfuration inhibitor. [Effects of the Invention]

[0011] According to the present invention, there can be provided an ultraviolet-curable organopolysiloxane composition containing, as a main component, an ultraviolet-curable organopolysiloxane that has a specific photodimerizable functional group such as a coumarin structure-containing group and does not require much energy for curing, and which is capable of giving a cured product (silicone rubber cured product) that exhibits excellent barrier properties against corrosive gases such as hydrogen sulfide gas, as well as an article having a cured product layer of the sulfurization inhibitor and a method for preventing the sulfurization of an article. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention will be described in detail below. The sulfuration inhibitor of the present invention is characterized by comprising an ultraviolet-curable organopolysiloxane composition containing an ultraviolet-curable organopolysiloxane represented by the general formula (1) described below.

[0013] [UV-curable organopolysiloxane composition] First, the ultraviolet-curable organopolysiloxane composition constituting the sulfuration inhibitor of the present invention contains an ultraviolet-curable organopolysiloxane represented by the following general formula (1) as the main component (base polymer). [ka] (In the formula, R 1 are independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, a hydroxyl group, an alkoxy group, or a monovalent photodimerizable functional group, and R 1 Among the (R), at least three on average are monovalent photodimerizable functional groups. a is an integer of 2 or more, b, c, and d are each an integer of 0 or more, b+c+d is an integer of 4 or more, and a+b+c+d is an integer of 6 or more. However,1 SiO 3 / 2 ) units of R 1 is two R 1 may be bonded to each other to form an alkylene group.)

[0014] The molecular structure of the ultraviolet-curable organopolysiloxane represented by the general formula (1) may be any of a linear, branched, or three-dimensional network structure, but usually the main chain is a diorganosiloxane unit (R 1 2SiO 2 / 2 ) repeating units, and both ends of the molecular chain are triorganosiloxy groups (R 1 3SiO 1 / 2 ) or the siloxane unit in the molecule is a linear diorganopolysiloxane (a=2, b is an integer of 4 or more, c=d=0) terminated with (R 1 3SiO 1 / 2 ) units, (R 1 2SiO 2 / 2 ) units and (R 1 SiO 3 / 2 a) unit (a is an integer of 2 or more, b and c are integers of 1 or more, and b+c is an integer of 4 or more, and d=0), and the siloxane units in the molecule are (R 1 3SiO 1 / 2 ) units, (R 1 2SiO 2 / 2 ) units and (SiO 4 / 2 a) is an integer of 2 or more, b and d are integers of 1 or more, and b+d is an integer of 4 or more, and c=0), and the siloxane units in the molecule are (R 1 3SiO 1 / 2 ) units and (SiO 4 / 2 Organopolysiloxane having a three-dimensional network structure consisting of (R) units (a is an integer of 2 or more, d is an integer of 4 or more, b=c=0), or siloxane units in the molecule are (R 1 3SiO 1 / 2 ) units, (R 1 SiO 3 / 2 ) units and (SiO 4 / 2 Preferably, the organopolysiloxane has a three-dimensional network structure consisting of units (a is an integer of 2 or more, c and d are integers of 1 or more, c+d is an integer of 4 or more, and b=0).

[0015] In the above general formula (1), R 1 are independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, a hydroxyl group, an alkoxy group, or a monovalent photodimerizable functional group, and R 1 Among these, at least three on average are monovalent photodimerization functional groups. Examples of unsubstituted or substituted monovalent hydrocarbon groups having 1 to 10 carbon atoms include alkyl groups having 1 to 10 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, hexyl, 2-ethylhexyl, and octyl; cycloalkyl groups having 3 to 10 carbon atoms, such as cyclohexyl; alkenyl groups having 2 to 10 carbon atoms, such as vinyl, allyl, and propenyl; aryl groups having 6 to 10 carbon atoms, such as phenyl and tolyl; and alkyl groups in which some of the hydrogen atoms of these groups have been substituted with halogen atoms or lower alkoxy groups having 1 to 4 carbon atoms, such as methoxy and ethoxy, such as chloromethyl, bromoethyl, 3,3,3-trifluoropropyl, methoxymethyl, methoxyethyl, ethoxymethyl, and ethoxyethyl. Among these, methyl and phenyl groups are preferred. Examples of the alkoxy group include lower alkoxy groups having 1 to 4 carbon atoms, such as a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, and a tert-butoxy group. In the above general formula (1), R 1 is preferably a methyl group or a methoxy group, excluding the monovalent photodimerizable functional group, and when it contains a methyl group and a methoxy group, the content ratio of the methyl group and the methoxy group is preferably 90 mol % or more (90 to 100 mol %) of the methyl group and 10 mol % or less (0 to 10 mol %) of the methoxy group relative to the total of the methyl group and the methoxy group. R 1 may be the same group or different groups.

[0016] In the above general formula (1), when c is 2 or more, two (R 1 SiO 3 / 2 ) units are each a monovalent hydrocarbon group, R 1They may be bonded to each other to form a bivalent hydrocarbon group having 2 to 20 carbon atoms, particularly an alkylene group. That is, they may form a branched structure (R 1 SiO 3 / 2 ) units of R 1 is two monovalent hydrocarbon groups R 1 They may be bonded together to form a divalent hydrocarbon group having 2 to 20 carbon atoms, particularly an alkylene group (for example, an ethylene group, an n-propylene group, an n-butylene group, an n-hexylene group, an n-heptylene group, an n-octylene group, an n-dodecylene group, etc.).

[0017] R in the above general formula (1) 1 Among these, at least three on average, preferably four or more on average, and more preferably 4 to 50 on average are monovalent photodimerizable functional groups (photocrosslinking groups). Examples of the monovalent photodimerizable functional groups contained therein include anthracenyl groups, chalcone groups, coumarin groups, cinnamic acid groups, stilbenyl groups, thymine groups, maleimide groups, azobenzyl groups, and styrene groups, as well as groups in which an alkylene group or an oxyalkylene group is bonded to a bond of each of these exemplary groups. Among these monovalent photodimerizable functional groups, a preferred example is a monovalent coumarin structure-containing group represented by the following general formula (2) (i.e., a group in which an alkylene group or an oxyalkylene group is bonded to a bond of a coumarin group). [ka] (In the formula, e is an integer of 1 to 10, and f is 0 or 1.)

[0018] In the above formula (2), e is an integer of 1 to 10, preferably an integer of 2 to 10, more preferably an integer of 3 to 10, and even more preferably an integer of 6 to 10. f is 0 or 1, and preferably 1.

[0019] In the above general formula (1), a is an integer of 2 or greater, preferably an integer of 2 to 10, and more preferably an integer of 2 to 6, b, c, and d are each an integer of 0 or greater, preferably b is an integer of 2 to 1,000, c is an integer of 0 to 10, and d is an integer of 0 to 10, and more preferably b is an integer of 10 to 500, c is an integer of 0 to 5, and d is an integer of 0 to 5. Furthermore, b+c+d is an integer of 4 or greater, preferably an integer of 4 to 1,000, and more preferably an integer of 12 to 500, and a+b+c+d is an integer of 6 or greater, preferably an integer of 10 or greater, more preferably an integer of 10 to 1,000, and even more preferably an integer of 20 to 500. The UV-curable organopolysiloxane represented by the general formula (1) preferably has a viscosity at 25°C of 25 to 500,000 mPa·s, particularly 500 to 100,000 mPa·s, and the value of a+b+c+d (degree of polymerization of the organopolysiloxane) is preferably such that the viscosity of the UV-curable organopolysiloxane falls within the above range.

[0020] In the present invention, the value of a+b+c+d (degree of polymerization), which is the total number of organosiloxane units in a molecule, or the molecular weight can usually be determined as the polystyrene-equivalent number-average degree of polymerization (or number-average molecular weight) in gel permeation chromatography (GPC) analysis using toluene or the like as a developing solvent (the same applies hereinafter). Viscosity can also be measured using a rotational viscometer (e.g., BL type, BH type, BS type, cone-plate type, rheometer, etc.) (the same applies hereinafter).

[0021] The ultraviolet-curable organopolysiloxane represented by the general formula (1) can be produced, for example, by mixing an organohydrogenpolysiloxane having at least three hydrogen atoms bonded to silicon atoms (SiH groups) in the molecule with a photodimerizable functional group derivative having an alkenyl group at the end, and allowing the mixture to react.

[0022] Here, examples of organohydrogenpolysiloxanes having at least three hydrogen atoms bonded to silicon atoms (SiH groups) in the molecule include those represented by the following general formula (1A). [ka] (In the formula, R 2 are independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms. a1 and a2 are each an integer of 0 or greater, and a1 + a2 is an integer of 2 or greater. b1 and b2 are each an integer of 0 or greater, and c and d are the same as above. a2 + b2 is an integer of 3 or greater, b1 + b2 + c + d is an integer of 4 or greater, and a1 + a2 + b1 + b2 + c + d is an integer of 6 or greater, provided that (R 1 SiO 3 / 2 ) units of R 1 is two R 1 may be bonded to each other to form an alkylene group.)

[0023] R in the above formula (1A) 2 The unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms includes R 1 Examples of the unsubstituted or substituted monovalent hydrocarbon groups having 1 to 10 carbon atoms include those listed above. Of these, methyl and phenyl groups are preferred.

[0024] In the above general formula (1A), a1 and a2 are each an integer of 0 or greater, preferably an integer of 0 to 10, more preferably an integer of 0 to 6, and a1+a2 is an integer of 2 or greater, preferably an integer of 2 to 10, more preferably an integer of 2 to 6. b1 and b2 are each an integer of 0 or greater, preferably an integer of 0 to 1,000, and b1+b2 is preferably an integer of 0 to 1,000 or an integer of 0 to 500. c and d are each an integer of 0 or greater, preferably an integer of 0 to 10, and d is an integer of 0 to 10, more preferably an integer of 0 to 5, and d is an integer of 0 to 5. a2+b2 is an integer of 3 or greater, preferably an integer of 4 or greater, more preferably an integer of 4 to 50. Furthermore, b1+b2+c+d is an integer of 4 or greater, preferably an integer of 4 to 1,000, and more preferably an integer of 12 to 500, and a1+a2+b1+b2+c+d is an integer of 6 or greater, preferably an integer of 10 or greater, more preferably an integer of 10 to 1,000, and even more preferably an integer of 20 to 500. Furthermore, the organohydrogenpolysiloxane represented by general formula (1A) above preferably has a viscosity at 25°C of 25 to 500,000 mPa·s, and particularly 500 to 100,000 mPa·s, and the value of a1+a2+b1+b2+c+d (degree of polymerization of the organopolysiloxane) is preferably such that the viscosity of the organohydrogenpolysiloxane falls within the above range.

[0025] Examples of photodimerization functional group derivatives having an alkenyl group at the terminal include an anthracenyl group, a chalcone group, a coumarin group, a cinnamic acid group, a stilbenyl group, a thymine group, a maleimide group, an azobenzyl group, a styrene group, and a group in which an alkylene group or an oxyalkylene group is bonded to the bond of each of these exemplary groups, and an alkenyl group (preferably a vinyl group) is bonded to the terminal of any of these groups. Among these photodimerization functional group derivatives, a coumarin derivative represented by the following general formula (2A) is preferred (i.e., a group in which an alkylene group, an oxyalkylene group, or a vinyl group is bonded to a coumarin group via an oxygen atom): [ka] (In the formula, e' is an integer of 0 to 8, preferably an integer of 1 to 8, more preferably an integer of 4 to 8. f is 0 or 1, preferably 1.)

[0026] The mixing ratio of the photodimerization functional group derivative having an alkenyl group at its terminal when reacting the above compound is preferably an amount such that the molar ratio of alkenyl groups in the photodimerization functional group derivative having an alkenyl group at its terminal to 1 mole of hydrogen atoms (SiH groups) bonded to silicon atoms in the organohydrogenpolysiloxane (Vi / SiH ratio) is 0.5 to 1.2, more preferably 0.7 to 1.1. If the Vi / SiH ratio is too low, it may not be possible to introduce a sufficient amount of photodimerization functional group for curing into the organopolysiloxane.

[0027] The reaction conditions are preferably such that an organic solvent such as toluene and a platinum group metal catalyst (in an amount equivalent to 1 to 100 ppm by mass of platinum relative to the organohydrogenpolysiloxane) are added to the compound and mixed at room temperature (23°C ± 15°C) to 100°C for 2 to 12 hours. After this mixing, the organic solvent such as toluene is removed under reduced pressure, followed by washing and removal with a lower alcohol having 5 or less carbon atoms such as methanol, thereby obtaining the UV-curable organopolysiloxane represented by the above formula (1). Note that, in formula (1), R 1 Among these, the alkoxy groups result from the reaction between the hydrogen atoms (SiH groups) bonded to the unreacted silicon atoms remaining in the organohydrogenpolysiloxane and the lower alcohol when the organohydrogenpolysiloxane is washed with the lower alcohol. The progress and completion of the above reaction are as follows: 29 Si-NMR spectrum, 1 This can be confirmed by the disappearance of the peaks of the reactive functional groups in the H-NMR spectrum.

[0028] The ultraviolet-curable organopolysiloxane composition constituting the sulfuration inhibitor of the present invention may contain optional components such as a photosensitizer and an organic solvent in addition to the ultraviolet-curable organopolysiloxane represented by general formula (1) above as the main component (base polymer), as needed.

[0029] Aromatic compounds containing a carbonyl group are often used as photosensitizers, but there are no particular limitations on the type of compound as long as it has a photosensitizing effect and is miscible with the ultraviolet-curable organopolysiloxane composition. Examples include isopropyl-9H-thioxanthene-9-one, xanthone, anthracene, anthrone, anthraquinone, benzophenone, 4,4'-bis(dimethylamino)benzophenone, 2,2-diethoxyacetophenone, 2,2'-dimethoxy-1,2-diphenylethan-1-one, 1-hydroxy-cyclohexyl-phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-one, 2-methyl-1[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butan-1-one, and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

[0030] When a photosensitizer is added, the amount is not particularly limited, but is preferably 0.001 to 10 parts by mass, and particularly preferably 0.1 to 1 part by mass, per 100 parts by mass of the UV-curable organopolysiloxane represented by the general formula (1) above. If the amount is less than 0.001 part by mass, the curing time may be long, and if it exceeds 10 parts by mass, the cost may be high. The photosensitizer may be used alone or in combination of two or more types.

[0031] The organic solvent is not particularly limited as long as it can dissolve the UV-curable organopolysiloxane and the photosensitizer and does not inhibit photoreactivity. Examples include isopropyl alcohol, tert-butyl alcohol, cyclohexanol, cyclohexanone, methylcyclohexane, methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, mesitylene, 1,4-dioxane, dibutyl ether, anisole, 4-methylanisole, ethoxybenzene, chlorobenzene, ethylene glycol, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, 2-methoxyethanol, diethylene glycol dimethyl ether, diethylene glycol monomethyl ether, 1-methoxy-2-propyl acetate, 1-ethoxy-2-propyl acetate, octamethylcyclotetrasiloxane, and hexamethyldisiloxane. These organic solvents may be used alone or in combination.

[0032] When an organic solvent is added, its amount is not particularly limited, but is preferably 0.1 to 100 parts by mass per 100 parts by mass of the UV-curable organopolysiloxane represented by the general formula (1). If the organic solvent is less than 0.1 part by mass, its effect as a solvent (reducing the viscosity of the composition) may be insufficient, while if it exceeds 100 parts by mass, the hardness of the resulting cured product may be significantly reduced and the sulfurization prevention effect intended by the present invention may not be achieved.

[0033] [Other ingredients] Furthermore, in addition to the components described above, the ultraviolet-curable organopolysiloxane composition that constitutes the sulfuration inhibitor of the present invention may contain the following fillers and additives, as long as the properties of the present invention are not impaired. Fillers include ground silica, fumed silica, calcium carbonate, zinc carbonate, aluminum hydroxide, aluminum oxide hydroxide, alumina, magnesium oxide, wet silica, and the like. Examples of additives include polyethers as wetters and thixotropy improvers, and non-reactive dimethyl silicone oils as plasticizers (for example, dimethyl polysiloxanes capped at both molecular chain ends with trimethylsilyl groups).

[0034] Furthermore, if necessary, colorants such as pigments and dyes, fluorescent brighteners, mildewproofing agents, antibacterial agents, surface modifiers such as non-reactive phenylsilicone oils as bleed oils, fluorosilicone oils, and organic liquids incompatible with silicones may also be added.

[0035] The ultraviolet-curable organopolysiloxane composition constituting the sulfuration inhibitor of the present invention is in an oily (liquid) state at room temperature (25°C ± 15°C) and can be cured by irradiation with ultraviolet light.

[0036] The ultraviolet light source for curing the ultraviolet-curable organopolysiloxane composition that constitutes the sulfuration inhibitor of the present invention is preferably a high-pressure mercury lamp, a medium-pressure mercury lamp, or an LED lamp, and the wavelength is preferably 365 nm, with the irradiation dose (cumulative light amount) being 1,000 to 50,000 mJ / cm. 2 For example, ultraviolet light with a wavelength of 365 nm is preferably used at 100 W / cm 2 It is recommended to irradiate for about 10 to 500 seconds at this intensity.

[0037] The sulfuration inhibitor of the present invention can be suitably used in electronic devices such as air conditioners, personal computers, and power tools. Specifically, it can be used as a sulfuration inhibitor coating agent for metal substrates such as circuit boards on which electric and electronic components are mounted in these electronic devices and metal substrates for liquid crystal display elements.

[0038] The sulfuration inhibitory performance of the sulfuration inhibitor of the present invention can be evaluated using a test specimen prepared by applying (coating) the above-described sulfuration inhibitor of the present invention (ultraviolet-curable organopolysiloxane composition) to the surface of a substrate by a conventional method to a predetermined thickness (for example, typically 10 to 2,000 μm, particularly about 10 to 1,000 μm), curing the coating film by ultraviolet irradiation, and forming a cured product layer of the sulfuration inhibitor (cured silicone rubber layer) of a predetermined thickness on the surface of the substrate, which is made of the cured product of the ultraviolet-curable organopolysiloxane composition (cured silicone rubber layer).

[0039] The sulfuration prevention performance of the substrate (test specimen) thus prepared, on which a cured product layer of the sulfuration inhibitor made of the cured product of the ultraviolet-curable organopolysiloxane composition has been formed, can be evaluated by the following evaluation method.

[0040] [Anti-sulfuration test method] 1) A test specimen is prepared by applying the sulfurization inhibitor (ultraviolet-curable organopolysiloxane composition) of the present invention to a substrate made of a metal (such as silver or copper) that is susceptible to reaction with sulfurous corrosive gases and then curing the composition to form (laminated) a layer of the cured sulfurization inhibitor on the substrate. 2) Place the test specimen prepared in 1) in a sealable container. 3) Sulfur powder is placed in the container from 2), or hydrogen sulfide or sulfur dioxide gas is sealed inside, and the container is then visually inspected for corrosion on the metal surface coated with the cured layer of sulfur inhibitor. The test temperature can be selected from room temperature (20°C ± 5°C) to 90°C, and the test period can be selected from 1 to 60 days. For example, the hydrogen sulfide concentration in the sealed container is kept constant between 3 and 10 ppm, and the specimen is kept at room temperature (25°C) for 7 days, after which the specimen's corrosion state is visually inspected.

[0041] The thickness of the anti-sulfurization agent to be applied is not particularly limited, but is preferably in the range of 10 to 2,000 μm, particularly 10 to 1,000 μm. If the thickness exceeds 2,000 μm, it becomes difficult to apply the agent in one go, and workability or takt time deteriorates.

[0042] The article of the present invention has a cured product layer of the above-mentioned sulfuration inhibitor of the present invention. Specific examples include circuit boards equipped with electric and electronic components, liquid crystal display elements, and other articles whose surfaces are partially or entirely coated with a cured product layer of the sulfuration inhibitor of the present invention. The thickness of this cured product layer is preferably 10 to 2,000 μm, more preferably 10 to 1,000 μm. If the thickness exceeds 2,000 μm, the sulfuration prevention performance may not be further improved, and if it is less than 10 μm, durability may be reduced.

[0043] The method for preventing sulfurization of an article of the present invention comprises the steps of applying the above-described sulfurization inhibitor of the present invention to at least a portion or all of the surface of an article and irradiating the sulfurization inhibitor with ultraviolet light to form a cured layer of the sulfurization inhibitor. That is, the sulfurization inhibitor of the present invention may be applied (coated) to a predetermined thickness (e.g., typically 10 to 2,000 μm, particularly about 10 to 1,000 μm) by a conventional method (e.g., knife coating or brush coating) to a portion or all of the surface of a circuit board or liquid crystal display element carrying electric or electronic components, and the coating film may be cured by ultraviolet irradiation under the above-mentioned conditions to form a cured layer of the sulfurization inhibitor (cured silicone rubber layer) of the UV-curable organopolysiloxane composition (cured silicone rubber) with a predetermined thickness on the surface of the circuit board or liquid crystal display element. [Example]

[0044] EXAMPLES Hereinafter, examples and comparative examples will be shown to specifically explain the present invention, but the present invention is not limited to the following examples. The viscosity is measured using a rotational viscometer at 25°C. Me, Vi, and Pr represent methyl, vinyl, and propyl groups, respectively, and room temperature below refers to 25°C. The film thickness of the cured layer of the sulfuration inhibitor (silicone coating film) was determined by measuring the difference in thickness of the substrate before and after the formation of the cured layer of the sulfuration inhibitor (silicone coating film) using a thickness gauge (UPRIGHT DIAL GAUGE, manufactured by Ozaki Seisakusho Co., Ltd.).

[0045] [Synthesis Example 1] A 500 mL separable flask was charged with 20.0 g of an organohydrogenpolysiloxane represented by the following formula (3), 5.96 g of a coumarin derivative represented by the following formula (4), and 30 g of toluene, to which a platinum catalyst (20 ppm in terms of platinum mass relative to the organohydrogenpolysiloxane) was added, followed by stirring for 4 hours at 100° C. The molar ratio (Vi / SiH ratio) of vinyl groups in the coumarin derivative represented by formula (4) to 1 mole of hydrogen atoms (SiH groups) bonded to silicon atoms in the organohydrogenpolysiloxane represented by formula (3) was 0.9. After removing the toluene under reduced pressure, the reaction mixture was washed with and removed from methanol to obtain 16.6 g of a brown oil represented by the following formula (5). 29 Si-NMR spectrum, 1 This was confirmed by the disappearance of the peaks of the reactive functional groups in the H-NMR spectrum. [ka] [ka] [ka]

[0046] [Synthesis Example 2] A 500 mL separable flask was charged with 20.0 g of an organohydrogenpolysiloxane represented by the following formula (6), 15.7 g of a coumarin derivative represented by the above formula (4), and 80 g of toluene, to which a platinum catalyst (20 ppm in terms of platinum mass relative to the organohydrogenpolysiloxane) was added, followed by stirring for 6 hours at 100° C. The molar ratio (Vi / SiH ratio) of vinyl groups in the coumarin derivative represented by formula (4) to 1 mole of hydrogen atoms (SiH groups) bonded to silicon atoms in the organohydrogenpolysiloxane represented by formula (6) was 1.0. After removing the toluene under reduced pressure, the reaction mixture was washed with and removed from methanol to obtain 12.1 g of a brown oil represented by the following formula (7). 29Si-NMR spectrum, 1 This was confirmed by the disappearance of the peaks of the reactive functional groups in the H-NMR spectrum. [ka] [ka]

[0047] [Example 1] The organopolysiloxane having a coumarin structure-containing group represented by the formula (5) was applied to an Ag-plated Ni substrate (25 mm × 50 mm × 0.5 mm thick), and ultraviolet light with a wavelength of 365 nm (LED UV light) was applied from an LED lamp at 100 mW / cm. 2 for 30 seconds (accumulated light intensity 3,000 mJ / cm 2 ) to cure the anti-sulfuration agent, forming a cured layer of the anti-sulfuration agent with a thickness of 150 μm, thereby obtaining specimen 1.

[0048] [Example 2] Example 2-1 100 parts by mass of an organopolysiloxane having a coumarin structure-containing group represented by the above formula (5) and 0.2 parts by mass of 2,2-diethoxyacetophenone were mixed to obtain composition 1. Composition 1 was applied to an Ag-plated Ni substrate (25 mm × 50 mm × 0.5 mm thick), and ultraviolet light with a wavelength of 365 nm (LED UV light) was irradiated from an LED lamp at 100 mW / cm. 2 for 3 minutes (accumulated light intensity 18,000 mJ / cm 2 ) to cure the anti-sulfuration agent, forming a cured layer of the anti-sulfuration agent with a thickness of 140 μm, thereby obtaining specimen 2-1. (Example 2-2) 100 parts by mass of an organopolysiloxane having a coumarin structure-containing group represented by the above formula (5) and 0.2 parts by mass of 2,2-diethoxyacetophenone were mixed to obtain composition 1. Composition 1 was applied to an Ag-plated Ni substrate (25 mm × 50 mm × 0.5 mm thick), and ultraviolet light with a wavelength of 365 nm (LED UV light) was irradiated from an LED lamp at 100 mW / cm. 2 for 3 minutes (accumulated light intensity 18,000 mJ / cm 2) to cure the anti-sulfuration agent, forming a cured layer of the anti-sulfuration agent with a thickness of 800 μm, thereby obtaining specimen 2-2. (Example 2-3) 100 parts by mass of an organopolysiloxane having a coumarin structure-containing group represented by the above formula (5) and 0.2 parts by mass of 2,2-diethoxyacetophenone were mixed to obtain composition 1. Composition 1 was applied to an Ag-plated Ni substrate (25 mm × 50 mm × 0.5 mm thick), and ultraviolet light with a wavelength of 365 nm (LED UV light) was irradiated from an LED lamp at 100 mW / cm. 2 for 3 minutes (accumulated light intensity 18,000 mJ / cm 2 ) to cure the anti-sulfuration agent, forming a cured layer of the anti-sulfuration agent with a thickness of 160 μm, thereby obtaining specimen 2-3. (Examples 2-4) 100 parts by mass of an organopolysiloxane having a coumarin structure-containing group represented by the above formula (5) and 0.2 parts by mass of 2,2-diethoxyacetophenone were mixed to obtain composition 1. Composition 1 was applied to an Ag-plated Ni substrate (25 mm × 50 mm × 0.5 mm thick), and ultraviolet light with a wavelength of 365 nm (LED UV light) was irradiated from an LED lamp at 100 mW / cm. 2 for 3 minutes (accumulated light intensity 18,000 mJ / cm 2 ) to cure the anti-sulfuration agent, forming a cured layer of the anti-sulfuration agent with a thickness of 70 μm, thereby obtaining specimen 2-4. (Examples 2-5) 100 parts by mass of an organopolysiloxane having a coumarin structure-containing group represented by the above formula (5) and 0.2 parts by mass of 2,2-diethoxyacetophenone were mixed to obtain composition 1. Composition 1 was applied to an Ag-plated Ni substrate (25 mm × 50 mm × 0.5 mm thick), and ultraviolet light with a wavelength of 365 nm (LED UV light) was irradiated from an LED lamp at 100 mW / cm. 2 for 30 seconds (accumulated light intensity 3,000 mJ / cm 2 ) to cure the anti-sulfuration agent, forming a cured layer of the anti-sulfuration agent with a thickness of 170 μm, thereby obtaining specimen 2-5.

[0049] [Example 3] 100 parts by mass of an organopolysiloxane having a coumarin structure-containing group represented by the above formula (7) and 0.2 parts by mass of 2,2-diethoxyacetophenone were mixed to obtain composition 2. Composition 2 was applied to an Ag-plated Ni substrate (25 mm × 50 mm × 0.5 mm thick), and ultraviolet light with a wavelength of 365 nm (LED UV light) was irradiated from an LED lamp at 100 mW / cm. 2 for 3 minutes (accumulated light intensity 18,000 mJ / cm 2 ) to cure the anti-sulfuration agent, forming a cured layer of the anti-sulfuration agent with a thickness of 170 μm, thereby obtaining specimen 3.

[0050] [Comparative Example 1] 80 parts by mass of polydimethylsiloxane with both molecular chain ends capped with dimethylvinylsiloxy groups and a viscosity of 600 mPa·s at 25°C, Me3SiO 1 / 2 Units, Me2ViSiO 1 / 2 Units, PrSiO 3 / 2 units, and SiO 4 / 2 Equal masses (10 parts by mass) of an organopolysiloxane resin with a three-dimensional network structure consisting of units, xylene, and a polydimethylsiloxane with both molecular chain terminals capped with dimethylvinylsiloxy groups and a viscosity of 5,000 mPa·s at 25°C were weighed out and mixed at room temperature for 20 minutes, followed by further mixing under reduced pressure for 20 minutes to obtain 30 parts by mass of a mixture. Next, 7 parts by mass of a γ-mercaptopropyl group-containing organopolysiloxane, 0.4 parts by mass of (3-acryloxypropyl)trimethoxysilane, and 0.8 parts by mass of 2,2-diethoxyacetophenone were added, and the mixture was mixed at room temperature for 20 minutes, followed by further mixing under reduced pressure for 20 minutes to obtain UV-curable organopolysiloxane Composition 3. Composition 3 was applied to an Ag-plated Ni substrate (25 mm × 50 mm × 0.5 mm thick) and cured by irradiating it with light from a metal halide lamp for 30 seconds to form a cured layer with a thickness of 170 μm, and specimen 4 was obtained.

[0051] The sulfuration prevention properties using hydrogen sulfide gas were evaluated using the test specimens 1 to 4 prepared as described above. The test results for test specimens 1 to 4 are shown in Tables 1 and 2. Testing Method 1) The prepared test specimen is placed in the chamber of a gas corrosion testing device (GH-180, manufactured by Yamazaki Seiki Kenkyusho Co., Ltd.). 2) The chamber in 1) is sealed with hydrogen sulfide gas so that the hydrogen sulfide concentration is 3 ppm or 10 ppm, and the chamber is placed in a room temperature environment (humidity 40-60% RH) and left as is for 7 days for aging treatment. 3) After the aging treatment, the presence or absence of corrosion on the coated Ag-plated Ni substrate is visually confirmed.

[0052] Evaluation method The presence or absence of corrosion in the Ag plating of the coated Ag-plated Ni substrate was evaluated using the following index. ○: The Ag plating is not corroded (no blackening, no discoloration of the silver film (Ag plating surface)) △: The Ag plating did not corrode (turn black), but the silver film (Ag plating surface) turned slightly yellow. ×: Ag plating corroded (blackened)

[0053] [Table 1]

[0054] [Table 2]

[0055] In the evaluation of sulfurization prevention properties using hydrogen sulfide gas, the results of test specimens 1 to 4 confirmed that a cured product layer (silicone coating film) obtained by curing a sulfurization inhibitor made of an ultraviolet-curable organopolysiloxane represented by the above formula (5) or an ultraviolet-curable organopolysiloxane composition containing an ultraviolet-curable organopolysiloxane represented by the above formula (5) or (7) exhibits superior sulfurization prevention performance to a cured product layer (silicone coating film) obtained by curing an ultraviolet-curable organopolysiloxane composition containing a conventional ultraviolet-curable organopolysiloxane.

Claims

1. A sulfuration inhibitor comprising an ultraviolet-curable organopolysiloxane composition containing an ultraviolet-curable organopolysiloxane represented by the following general formula (1): 【Chemical 1】 (In the formula, R 1 are independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, a hydroxyl group, an alkoxy group, or a group represented by the following general formula (2): 【Chemistry 2】 (In the formula, e is an integer of 1 to 10, and f is 0 or 1.) is a coumarin structure-containing group represented by R 1 Among these, at least three on average are coumarin structure-containing groups represented by the general formula (2). a is an integer of 2 or more, b, c, and d are each an integer of 0 or more, b+c+d is an integer of 4 or more, and a+b+c+d is an integer of 6 or more. However, (R 1 SiO 3 / 2 ) R in units 1 is two R 1 may be bonded to each other to form an alkylene group.)

2. In general formula (1), R 1 2. The sulfuration inhibitor according to claim 1, wherein an average of at least four of the groups are coumarin structure-containing groups represented by the general formula (2).

3. The sulfurization inhibitor according to claim 1, wherein the ultraviolet-curable organopolysiloxane composition contains 100 parts by mass of the ultraviolet-curable organopolysiloxane represented by general formula (1), 0.001 to 10 parts by mass of a photosensitizer, and / or 0.1 to 100 parts by mass of an organic solvent.

4. An article having a layer of the cured product of the sulfurization inhibitor according to any one of claims 1 to 3.

5. A method for preventing sulfuration of an article, comprising the steps of applying the sulfuration inhibitor according to any one of claims 1 to 3 to at least a part or all of the surface of the article, and irradiating the sulfuration inhibitor with ultraviolet light to form a cured layer of the sulfuration inhibitor.

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