Curable liquid silicone composition and cured product thereof

Abstract

The curable liquid silicone composition exhibits single-component storability at room temperature in a sealed container, can be cured without heating at room temperature by using moisture in the atmosphere during use, and can form a silicone rubber cured product or a silicone gel cured product. The curable liquid silicone composition contains (A) a linear or branched diorganopolysiloxane having at least one alkenyl group in one molecule and (B) a linear or branched organohydrogenpolysiloxane having at least two hydrogen atoms bonded to a silicon atom in one molecule at a specific ratio. (C) a platinum catalyst mixture containing a platinum catalyst and a phosphite ester compound in an amount of 0.5-3 moles per 1 mole of platinum atoms; and (D) a hydrolysis reaction catalyst.

Description

TECHNICAL FIELD

[0001] The present application relates to a curable liquid silicone composition which exhibits one-component storage at room temperature (23°C ± 15°C, same below), cures at room temperature using moisture in the atmosphere, and is capable of forming a silicone rubber cured product (silicone elastomer) or a silicone gel cured product, and a cured product thereof. BACKGROUND

[0002] In order to achieve carbon neutrality until 2050, various companies are using environmentally friendly materials. Among them, heating and curing type compositions which require a high-temperature heating process requiring a large amount of energy, time, and equipment need to be improved. In addition, in order to use materials simply, and further to prevent errors in the use stage, there is a tendency to prefer one-component materials.

[0003] As a cross-linking reaction which is one-component and capable of curing without heating, there are cross-linking reactions which significantly shorten the storage in condensation reactions, ultraviolet radical reactions, or addition reactions, cross-linking reactions capable of activating a catalyst with ultraviolet light. However, in all of the cross-linking reactions, the deep curing property at the time of curing, or the curing property in the dark with ultraviolet light does not meet the needs, and there are restrictions on the uses that can be used.

[0004] Among them, in the technology of curing silicone compositions into rubber or gel in cross-linking using an addition reaction using a platinum catalyst, there are technologies aimed at one-component storage, usable time, and curing at lower temperatures of unreacted compositions.

[0005] In Japanese Patent No. 2722304 (Patent Document 1), a method of adding an amine compound having an ethylenediamine skeleton to a silicone composition cured in cross-linking using an addition reaction using a platinum catalyst is proposed.

[0006] In Japanese Patent No. 4530147 (Patent Document 2), a method of using a catalyst obtained by heat aging a specific phosphite compound with a platinum catalyst is proposed.

[0007] However, if the silicone composition obtained using the above technology is exposed to a temperature exceeding 50°C for a long time, thickening and gelation occur, and therefore, for performance stability, low-temperature conditions are required in storage and transportation.

[0008] In International Publication No. 2022 / 050103 (Patent Document 3), in order to solve such a problem, a one-component silicone composition which is stable in properties and physical properties even in a state of being exposed to a temperature exceeding 50°C for a long time is proposed by adding a specific phosphite compound to a branched organic polysiloxane and an organic hydrogen polysiloxane having a specific structure and a platinum catalyst. However, when it is cured in a short time, heating at around 100 to 160°C is required.

[0009] Prior Art Documents

[0010] Patent Documents

[0011] Patent Document 1: Japanese Patent No. 2722304

[0012] Patent Document 2: Japanese Patent No. 4530147

[0013] Patent Document 3: International Publication No. 2022 / 050103

[0014] Patent Document 4: U.S. Patent No. 3220972

[0015] Patent Document 5: U.S. Patent No. 3159601

[0016] Patent Document 6: U.S. Patent No. 3159662

[0017] Patent Document 7: U.S. Patent No. 3775452

[0018] Patent Document 8: U.S. Patent No. 4510094

[0019] Patent Document 9: U.S. Patent No. 4530879 SUMMARY

[0020] Problems to be Solved by the Invention

[0021] The present invention has been achieved in view of the above-described actual circumstances, and aims to provide a cured liquid silicone composition which exhibits one-component storage properties at room temperature in a closed container, can utilize moisture in the atmosphere at the time of use, and can form a silicone rubber cured product and a silicone gel cured product without heating at room temperature, and a cured product thereof.

[0022] Means for Solving the Problems

[0023] To achieve the above objectives, the inventors conducted in-depth research and discovered that a curable liquid organosilicon composition containing, in a specific ratio, a linear or branched diorganopolysiloxane having at least one alkenyl group in one molecule, a linear or branched organohydrogen polysiloxane having at least two hydrogen atoms bonded to silicon atoms in one molecule, a platinum catalyst mixture containing a platinum catalyst and a specific amount of phosphite compound, and a hydrolysis reaction catalyst exhibits single-component preservation at room temperature in a sealed container and cures at room temperature without heating using atmospheric moisture during use, thus completing the present invention.

[0024] The curable liquid silicone composition of the present invention cures at room temperature without heating by utilizing moisture in the atmosphere, thus enabling curing even in areas that are difficult to cure, such as dark areas that are not exposed to ultraviolet light, which is a problem for ultraviolet-curable liquid silicone compositions.

[0025] Therefore, the present invention provides curable liquid silicone compositions and cured products thereof that are capable of being cured to form silicone rubber cured products (silicone elastomers) or silicone gel cured products, as shown below.

[0026] [1] A curable liquid silicone composition containing:

[0027] (A) A linear or branched diorganopolysiloxane having at least one alkenyl group in one molecule,

[0028] (B) A linear or branched organohydrogen polysiloxane having at least two hydrogen atoms bonded to silicon atoms in one molecule: in such amounts that, relative to 1 mole of alkenyl group in component (A), the number of hydrogen atoms bonded to silicon atoms in component (B) is 0.5 to 4 moles.

[0029] (C) A platinum catalyst mixture comprising a platinum catalyst and a phosphite compound in an amount of 0.5 to 3 moles relative to 1 mole of platinum atoms: the amount being such that, converted from the mass of platinum atoms in component (C) relative to the total mass of components (A) and (B), it is 0.1 to 1000 ppm.

[0030] (D) Hydrolysis catalyst: 0.01 to 3% of the total mass of components (A) and (B).

[0031] [2] The curable liquid silicone composition according to [1] is a single-component composition.

[0032] [3] The curable liquid silicone composition according to [1] or [2] further comprises (E) a dehydrating agent: 0.01 to 5 by mass of the total mass of component (A) and component (B).

[0033] [4] The curable liquid silicone composition according to any one of [1] to [3] further comprises (F) a platinum catalyst compound that can be activated by ultraviolet light: in an amount such that, when converted to the mass of platinum atoms in component (F) relative to the total mass of components (A) and (B), it is 0.1 to 1000 ppm.

[0034] [5] The curable liquid silicone composition according to any one of [1] to [4] further comprises (G) a photoinitiator: 0.01 to 3 by mass of the total mass of component (A) and component (B).

[0035] [6] The cured product of the curable liquid silicone composition according to any one of [1] to [5].

[0036] The effects of the invention

[0037] The curable liquid silicone composition of the present invention exhibits single-component preservation at room temperature in a sealed container and cures at room temperature without heating by utilizing atmospheric moisture. In use, the phosphite compound, which functions as a control agent for the platinum catalyst, hydrolyzes upon contact with atmospheric moisture (humidity) in the presence of a hydrolysis catalyst, becoming phosphonic acid. This phosphite then ceases to function as a control agent, and the platinum catalyst is activated, acting as a catalyst for the hydrosilylation addition reaction, thereby curing the silicone.

[0038] The curable liquid silicone composition of the present invention possesses sufficient "long-term single-component shelf life at room temperature in a sealed container" for storage and transportation under refrigeration to room temperature. Furthermore, it cures at room temperature in the atmosphere without heating during use, thus contributing to energy conservation and the production of SDG-compliant components and products. In addition, by adding a platinum catalyst activated by ultraviolet light, and irradiating the product with ultraviolet light during curing, the curing reaction rate is increased, thereby improving workability. Attached Figure Description

[0039] Figure 1 This is a schematic diagram illustrating the ultraviolet irradiation method used in the shadow curing property measurement in an embodiment of the present invention.

[0040] Figure 2 This is a schematic diagram illustrating the evaluation area for measuring the curability of the shadow area in an embodiment of the present invention. Detailed Implementation

[0041] The present invention will now be described in detail.

[0042] [Curing liquid silicone composition]

[0043] The curable liquid silicone composition (curable liquid silicone rubber composition or curable liquid silicone gel composition) of the present invention is formulated with components (A) to (D) described below, and other components that may be used as needed.

[0044] [(A) Alkenyl-containing diorganopolysiloxanes]

[0045] (A) The alkenyl-containing diorganopolysiloxane is a linear or branched diorganopolysiloxane having at least one alkenyl group in one molecule, which functions as the main agent (base polymer) in the curable liquid silicone composition of the present invention (hereinafter also referred to as the composition of the present invention). Generally, it is a linear diorganopolysiloxane whose main chain portion is essentially composed of repeating diorganosiloxane units and whose molecular chain ends are capped with triorganosiloxy groups. It may also be a branched diorganopolysiloxane in which a branched structure is included in a part of the siloxane structure constituting the molecular chain.

[0046] (A) The alkenyl-containing diorganopolysiloxane contains at least one (usually 1 to 50), preferably 1 to 20, more preferably 1 to 10, and even more preferably 1 or 2 alkenyl groups in one molecule. Examples of alkenyl groups include vinyl, allyl, propenyl, isopropenyl, butenyl, hexenyl, cyclohexenyl, etc., which typically have about 2 to 8 carbon atoms. This alkenyl group can be bonded to silicon atoms at the ends of the molecular chain or to silicon atoms at the non-ends (midway) of the molecular chain. Preferably, it contains at least one alkenyl group bonded to silicon atoms at both ends of the molecular chain. In this case, the alkenyl group may exist only at both ends of the molecular chain, or it may exist at both ends of the molecular chain and at the non-ends (midway) of the molecular chain.

[0047] Examples of such diorganopolysiloxanes containing alkenyl groups include linear diorganopolysiloxanes represented by the following general formula (1).

[0048] [Chemistry 1]

[0049]

[0050] (where R) 1 Independently, it is an unsubstituted or substituted monovalent hydrocarbon group without aliphatic unsaturated bonds. X is an alkenyl group, and at least one is contained in one molecule. n is an integer greater than or equal to 0, m is an integer greater than or equal to 0, a is an integer from 0 to 3 independently for each bonded silicon atom, and at least one of a and m at both ends is an integer greater than or equal to 1.

[0051] In the above formula (1), R is used as 1Unsubstituted or substituted monovalent hydrocarbon groups without aliphatic unsaturated bonds, for example, monovalent hydrocarbon groups with 1 to 12 carbon atoms, preferably 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, specifically, alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, etc.; cycloalkyl groups such as cyclopentyl, cyclohexyl, cycloheptyl, etc.; aryl groups such as phenyl, tolyl, xylyl, naphthyl, biphenyl, etc.; aralkyl groups such as benzyl, phenylethyl, phenylpropyl, methylbenzyl, etc.; and these groups The group is formed by substituting part or all of the hydrogen atoms bonded to the carbon atom with halogen atoms such as fluorine, chlorine, and bromine, or cyano groups, such as chloromethyl, 2-bromoethyl, 3-chloropropyl, 3,3,3-trifluoropropyl, chlorophenyl, fluorophenyl, cyanoethyl, 3,3,4,4,5,5,6,6,6-nonafluorohexyl, etc., preferably unsubstituted or substituted alkyl groups with 1 to 3 carbon atoms such as methyl, ethyl, propyl, chloromethyl, bromoethyl, 3,3,3-trifluoropropyl, cyanoethyl, etc., and unsubstituted or substituted phenyl groups such as phenyl, chlorophenyl, fluorophenyl, etc., more preferably methyl or phenyl.

[0052] In the above formula (1), the alkenyl group as X can be, for example, vinyl, allyl, propenyl, isopropenyl, butenyl, hexenyl, cyclohexenyl and other alkenyl groups with about 2 to 8 carbon atoms, among which vinyl, allyl and other lower alkenyl groups are preferred.

[0053] In the above formula (1), n ​​is an integer greater than or equal to 0, preferably an integer between 10 and 2000, more preferably an integer between 50 and 1200, and m is an integer greater than or equal to 0, preferably an integer between 0 and 40, more preferably an integer between 0 and 20. Furthermore, n and m are preferably integers satisfying 10 ≤ n + m ≤ 2000, more preferably integers satisfying 50 ≤ n + m ≤ 1200, and are integers satisfying 0 ≤ m / (n + m) ≤ 0.2. In this case, the units within the parentheses enclosed by n and m can be arranged randomly.

[0054] In the above formula (1), a is an integer from 0 to 3 for each bonded silicon atom, preferably 0 or 1.

[0055] In addition, as an organopolysiloxane containing an alkenyl group, examples include those in the above general formula (1) except for the 1-functional silanoxy unit (X) constituting the molecule. a R 1 (3-a) SiO 1 / 2 (unit) and 2-functional siloxane units ((X)(R) 1 SiO 2 / 2 Unit, (R) 1 )2SiO 2 / 2In addition to the unit, the molecule also contains a small number of trifunctional siloxane units that form branch points (i.e., composed of (R... 1 SiO 3 / 2 or (X)SiO 3 / 2 Branched diorganopolysiloxanes (represented by silsesquioxane units).

[0056] In addition, such alkenyl-containing diorganopolysiloxanes preferably have a viscosity of 10 to 1,000,000 millipascals at 23°C, and particularly preferably around 100 to 500,000 millipascals.

[0057] In this invention, the number of repeats (or degree of polymerization) of the two organosiloxane units in one molecule can usually be determined using toluene or the like as the elution solvent, or by converting the number-average molecular weight (or number-average degree of polymerization) of polystyrene in gel permeation chromatography (GPC) analysis. Furthermore, viscosity can usually be measured using a rotational viscometer (e.g., BL type, BH type, BS type, cone-plate type, rheometer, etc.) at 23°C.

[0058] (A) The alkenyl-containing diorganopolysiloxane can be used alone or in combination of two or more. In addition, in order to prevent fluctuations in shelf life caused by differences in the amount of water in the composition, the amount of water contained in the alkenyl-containing diorganopolysiloxane of (A) can be reduced in advance before mixing in the composition, for example, preferably by heating, depressurization, or a combination thereof.

[0059] [(B) Organohydrogen polysiloxane]

[0060] (B) The organohydrogen polysiloxane is an organohydrogen polysiloxane having at least two (usually 2 to 200), preferably about 2 to 100, hydrogen atoms (SiH groups) bonded to silicon atoms in one molecule, in a straight-chain or branched (branched chain or three-dimensional network structure (resin structure)) form, and functions as a curing agent (crosslinking agent) for the curable liquid silicone composition of the present invention.

[0061] Examples of such organohydrogen polysiloxanes include linear or branched organohydrogen polysiloxanes represented by the following average composition formula (2).

[0062] [Chemistry 2]

[0063]

[0064] (where R) 2 Independently, it is an unsubstituted or substituted monovalent hydrocarbon group without aliphatic unsaturated bonds, and b and c are numbers in the range of 0.001≤b≤1.2, 0.8≤c≤2, and 0.8<b+c≤3, preferably numbers in the range of 0.05≤b≤1, 1.2≤c≤2, and 1.5≤b+c≤2.7.

[0065] In the above equation (2), R is... 2 Unsubstituted or substituted monovalent hydrocarbon groups without aliphatic unsaturated bonds can be listed as R, which is the general formula (1) above. 1 Examples of the same groups as those shown include groups with 1 to 12 carbon atoms, preferably 1 to 10 carbon atoms, more preferably 1 to 7 carbon atoms, and particularly preferably lower alkyl groups, phenyl groups, 3,3,3-trifluoropropyl groups with 1 to 3 carbon atoms such as methyl.

[0066] As component (B), an organohydrogen polysiloxane that is liquid at room temperature (23°C ± 15°C, the same below) is preferably used, having approximately 2 to 300, particularly 3 to 150, and especially 3 to 100 silicon atoms per molecule. Furthermore, the hydrogen atoms bonded to the silicon atoms can be located at either the end of the molecular chain, the middle (non-end) of the molecular chain, or both.

[0067] Examples of such organohydrogen polysiloxanes include, for instance, 1,1,3,3-tetramethyldisiloxane, 1,1,3,3,5,5-hexamethyltrisiloxane, tris(dimethylhydrosiloxy)methylsilane, tris(dimethylhydrosiloxy)phenylsilane, trimethylsiloxy-terminated methylhydropolysiloxane, trimethylsiloxy-terminated dimethylsiloxane-methylhydrosiloxane copolymer, trimethylsiloxy-terminated diphenylsiloxane-methylhydrosiloxane copolymer, trimethylsiloxy-terminated methylphenylsiloxane-methylhydrosiloxane copolymer, and trimethylsiloxy-terminated methylhydrosiloxane copolymer. Dimethylsiloxane-diphenylsiloxane-methylhydrosiloxane copolymer, dimethylpolysiloxane with dimethylhydrosiloxy groups at both ends of the molecular chain, dimethylhydrosiloxy groups at both ends of the molecular chain, dimethylhydrosiloxy groups at both ends of the molecular chain, dimethylhydrosiloxy groups at both ends of the molecular chain, dimethylhydrosiloxy groups at both ends of the molecular chain, dimethylhydrosiloxy groups at both ends of the molecular chain, dimethylhydrosiloxy groups at both ends of the molecular chain, dimethylhydrosiloxy groups at both ends of the molecular chain, dimethylhydrosiloxy groups at both ends of the molecular chain, dimethylhydrosiloxy groups at both ends of the molecular chain, dimethylhydrosiloxy groups at both ends of the molecular chain, dimethylhydrosiloxy groups at both ends of the molecular chain, dimethylhydrosiloxy groups at both ends of the molecular chain, dimethylhydrosiloxy groups at both ends of the molecular chain, dimethylhydrosiloxy groups, dimethylsiloxane-diphenylsiloxane-diphenylsiloxane-methylhydrosiloxane copolymer, composed of dimethylhydrosiloxy units and SiO 4 / 2 Organosilicon resins with a three-dimensional network structure comprising trimethylsiloxy units, optionally including trimethylsiloxy units, dimethylsiloxane units, methylhydrosiloxane units, hydrosilsesquioxane units and / or methylsilsesquioxane units, and compounds in which some or all of the methyl groups in the above-described exemplary compounds are replaced with other alkyl or phenyl groups, etc.

[0068] The linear or branched organohydrogen polysiloxanes used in the compositions of the present invention can be obtained by known methods, for example, by using compounds selected from the following general formula: R 2 SiHCl2 and R 2 2SiHCl (where R) 2 Same as above. ( ) at least one of the chlorosilanes (co-)hydrolyzed and condensed, or the chlorosilane is reacted with a group selected from the following general formula: R 2 3SiCl and R 2 2SiCl2 (where R) 2 Same as above. It is obtained by co-hydrolysis and condensation of at least one of the chlorosilanes in the group. Alternatively, the organohydrogen polysiloxane may be a product of equilibrating the polysiloxane obtained by such (co)hydrolysis and condensation.

[0069] From the viewpoint of forming well-cured silicone rubber and organosilicon gel, the amount of organohydrogen polysiloxane in component (B) is such that, relative to 1 mole of alkenyl groups in the alkenyl-containing diorganopolysiloxane of component (A), the amount of hydrogen atoms (i.e., SiH groups) bonded to silicon atoms in the organohydrogen polysiloxane of component (B) is 0.5 to 4 moles, preferably 0.8 to 2.5 moles.

[0070] (B) The organohydrogen polysiloxane can be used alone or in combination with two or more. In addition, in order to prevent fluctuations in shelf life caused by differences in the amount of water in the composition, the amount of water contained in the organohydrogen polysiloxane of (B) can be reduced in advance before mixing in the composition, for example, by heating, reducing pressure, or combining them.

[0071] [A mixture of platinum catalysts containing (C) platinum catalyst and phosphite compounds]

[0072] (C) The platinum catalyst mixture contains a platinum catalyst and a phosphite compound in an amount of 0.5 to 3 moles relative to 1 mole of platinum atoms. The phosphite compound inhibits the activation of the platinum catalyst. When the composition is used, the phosphite compound undergoes a hydrolysis reaction by utilizing atmospheric moisture to become phosphonic acid, thus ceasing to function as a control agent. Consequently, the platinum catalyst is activated and functions as a catalyst for the hydrosilylation addition reaction.

[0073] (C) The platinum catalyst used in the composition is a conventionally used catalyst containing platinum or platinum compounds to promote the hydrosilylation addition reaction. Specific examples include elemental platinum (including platinum black); H₂PtCl₄ xH2O, H2PtCl6 xH2O, NaHPtCl6 xH2O, KHPtCl6 xH2O, Na2PtCl6 xH2O, K2PtCl4 xH2O, PtCl4 xH2O, PtCl2, Na2HPtCl4 Platinum chloride, chloroplatinic acid, and chloroplatinate, such as xH2O (where x is an integer from 0 to 6, preferably 0 or 6); alcohol-modified chloroplatinic acid (see US Patent No. 3,220,972 (Patent Document 4)); coordination compounds (complexes) of chloroplatinic acid with olefins (see US Patent Nos. 3,159,601 (Patent Document 5), 3,159,662 (Patent Document 6), and 3,775,452 (Patent Document 7)); complexes of platinum chloride, chloroplatinic acid, or chloroplatinate with vinyl-containing siloxanes, particularly with vinyl-containing cyclic siloxanes; complexes of platinum with alcohols or vinyl-containing siloxanes, etc.

[0074] The platinum catalyst is preferably used by dissolving it in solvents such as toluene, lower alcohols, higher alcohols, or organosilicon compounds. The platinum atom content (concentration) in the solution is preferably 0.1–2% by mass.

[0075] Phosphite compounds used as components (C) include, for example, compounds represented by the following general formula (3).

[0076] [Chemistry 3]

[0077]

[0078] (where R) 3 (Y is independently a monovalent aliphatic hydrocarbon group with 1 to 10 carbon atoms, and Y is independently a hydrogen atom or a methyl group.)

[0079] In the above formula (3), R 3 It is a monovalent aliphatic hydrocarbon group with 1 to 10 carbon atoms, preferably 1 to 6. Examples include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, hexyl, cyclohexyl, octyl, and decyl, as well as alkenyl groups such as vinyl, allyl, propenyl, isopropenyl, butenyl, and isobutylenyl. It is preferred to have a monovalent hydrocarbon group without aliphatic unsaturated bonds, among which alkyl groups are preferred, and methyl, ethyl, and propyl groups are particularly preferred. Wherein, R 3 They can be the same or different.

[0080] In addition, in the above formula (3), Y is a hydrogen atom or a methyl group, wherein a hydrogen atom is preferred.

[0081] Specific examples of phosphite compounds having the structure represented by the above formula (3) include triisopropyl phosphite, tri(tert-butyl) phosphite, tri(sec-butyl) phosphite, tri(1-ethylpropyl) phosphite, tri(1-ethylbutyl) phosphite, tri(1-propylbutyl) phosphite, etc.

[0082] Regarding the amount of the aforementioned phosphite compound added, it is added in an amount of 0.5 to 3 moles relative to 1 mole of platinum atoms in the aforementioned platinum catalyst. When the amount of phosphite compound is less than 0.5 moles relative to 1 mole of platinum atoms, the controllability of the platinum catalyst decreases, and the single-component shelf life at room temperature decreases. Furthermore, when the amount of phosphite compound exceeds 3 moles relative to 1 mole of platinum atoms, a large amount of phosphite compound capable of coordinating with platinum atoms exists, thus requiring time for the platinum catalyst to activate and function as a catalyst for the hydrosilylation addition reaction, and reducing the moisture (aerobic) curability. The preferred amount of the aforementioned phosphite compound added is 0.8 to 2 moles relative to 1 mole of platinum atoms in the aforementioned platinum catalyst, more preferably 1.0 to 1.3 moles.

[0083] A platinum catalyst mixture comprising a platinum catalyst and a phosphite compound can be obtained, for example, by uniformly mixing the platinum catalyst and the phosphite compound under a nitrogen atmosphere at room temperature (23°C) and allowing it to stand for at least 24 hours to mature. When preparing this platinum catalyst mixture, it is preferable that the platinum catalyst and the phosphite compound are each dissolved in a solvent as needed.

[0084] The amount of component (C), which comprises a platinum catalyst mixture containing a platinum catalyst and a phosphite compound, relative to the total mass of components (A) and (B), in terms of the mass of platinum atoms, is 0.1 to 1000 ppm, preferably 1 to 300 ppm. If component (C) is too small, the curable liquid silicone composition will not cure; if it is too large, the probability of generating activated platinum catalyst increases, and the single-component retention of the composition is significantly reduced.

[0085] [(D) Hydrolysis reaction catalyst]

[0086] The hydrolysis catalyst in component (D) is a catalyst used to promote the hydrolysis reaction of the phosphite compound in component (C). When used, the curable liquid silicone composition of the present invention, in the presence of the hydrolysis catalyst in component (D), allows the phosphite compound, which functions as a control agent for the platinum catalyst in component (C), to hydrolyze using atmospheric moisture (humidity) to become phosphonic acid. This phosphite compound then ceases to function as a control agent, and the platinum catalyst is activated, acting as a catalyst for the hydrosilylation addition reaction, thereby curing.

[0087] Examples of metal compounds that can serve as catalysts for the hydrolysis reaction of component (D) include titanates (tetra(isopropyl) titanate (TPT), tetrabutyl titanate (TBT), tetra(2-ethylhexyl) titanate (TOT), etc.), titanium chelates (diisopropoxybis(ethyl acetoacetate) titanium, tetraacetylacetone titanium, etc.), and tin compounds (dibutyldimethoxytin, dibutyltin dilaurate, etc.).

[0088] The preferred amount of component (D) is 0.01 to 3% by mass of the total mass of components (A) and (B), and particularly preferably 0.01 to 1% by mass. When the amount added is less than 0.01% by mass, the effect as a catalyst for the hydrolysis reaction is insufficient, and when it exceeds 3% by mass, the single-component preservation at room temperature is reduced.

[0089] [Other ingredients]

[0090] In the curable liquid silicone composition of the present invention, in addition to the components (A) to (D) above, various optional components may be added as needed, without prejudice to the purpose of the present invention.

[0091] [(E) Dehydrating agent]

[0092] In the curable liquid silicone composition of the present invention, and optionally as an ingredient, a dehydrating agent of component (E) can be formulated to remove moisture from the composition. By formulating a dehydrating agent of component (E), superior shelf life can be obtained.

[0093] The curable liquid silicone composition of the present invention, as described above, exhibits single-component preservation at room temperature in a sealed container and can utilize atmospheric moisture for curing without heating at room temperature. Therefore, by reducing the water content in each component and the water content in the mixed composition, the improved single-component preservation of the curable liquid silicone composition is confirmed. The mechanism of consuming moisture from each component in the composition and trace amounts of moisture entering from outside the container within the composition (using a (E) dehydrating agent) while stored in a sealed container is useful in ensuring single-component preservation.

[0094] As a dehydrating agent for component (E), it can be an inorganic compound or an organic compound, as long as it does not impair the function of components (A), (B), (C) and (D) mentioned above. It varies depending on the dehydrating agent. Sometimes foaming is caused by compounds produced as byproducts of the dehydration reaction. In addition, there are many dehydrating agents that cause the decomposition of organohydrogen polysiloxanes in component (B) and reduce the catalytic activity of platinum catalysts in component (C).

[0095] Therefore, as a dehydrating agent for component (E), and as a dehydrating agent capable of efficiently performing dehydration within the system, silyl ketones (including silyl ketone acetals), silyl enol esters, and α-silyl esters are preferred. These compounds are byproducts of dehydration and do not impair the function of components (A), (B), (C), and (D) above. They are soluble in the curable liquid silicone composition, thus enabling the preparation of a stable curable liquid silicone composition. Since silyl ketones (including silyl ketone acetals) and α-silyl esters undergo dehydration reactions under non-alkaline conditions, they do not cause the decomposition of the organohydrogen polysiloxane in component (B) or a decrease in the catalytic activity of the platinum catalyst in component (C).

[0096] Examples of silyl ketones (including silyl ketone acetals) include 1-methoxy-2-methyl-1-(trimethylsilyloxy)propene, dimethyl ketone trimethylsilyl acetal, and tert-butoxy-1-(trimethylsilyloxy)propene.

[0097] Examples of α-silyl esters include ethyl 2-(trimethoxysilyl)propionate (ECMS) and octyl 2-(methyldimethoxysilyl)propionate (OCMS-2).

[0098] When the dehydrating agent of component (E) is incorporated, it can be added to each component beforehand, during the preparation of the composition, or later in the prepared composition. Furthermore, when component (E) is incorporated, its addition amount is preferably 0.01 to 5% by mass of the total mass of components (A) and (B), and particularly preferably 0.1 to 2% by mass. Excessive addition of component (E) may sometimes adversely affect the changes in the physical properties of the cured material during heat resistance.

[0099] Furthermore, since the hydrolysis catalyst of component (D) also promotes the reaction between the dehydrating agent of component (E) and water, when component (E) is mixed in, it not only promotes the hydrolysis reaction of phosphite compounds, but also promotes the dehydration effect within the system.

[0100] [(F) Platinum catalyst compounds that can be activated by ultraviolet light]

[0101] Furthermore, in the curable liquid silicone composition of the present invention, as an optional component, a platinum catalyst compound that can be activated by ultraviolet light can be mixed in component (F) to improve the curing reaction rate.

[0102] As described above, the curable liquid silicone composition of the present invention exhibits single-component shelf life at room temperature in a sealed container. It can be cured at room temperature without heating using atmospheric moisture, but complete curing requires approximately one week. Therefore, to improve the curing reaction rate, it is useful to add a platinum catalyst compound (F) that can be activated by ultraviolet light. The curing reaction rate is improved for areas directly exposed to ultraviolet light, thus enhancing workability, while areas that are difficult to cure, such as dark areas not exposed to ultraviolet light, are subsequently cured.

[0103] The curable liquid organosilicon composition of the present invention comprises (F) a platinum catalyst activated by light with a wavelength of 200-500 nm, preferably ultraviolet light with a wavelength of 200-400 nm, i.e., a platinum catalyst (hydrosilane addition reaction catalyst) that is inactive under light-shielding conditions but becomes active at room temperature by irradiation with light with a wavelength of 200-500 nm, preferably ultraviolet light with a wavelength of 200-400 nm, and is capable of promoting the hydrogen silane addition reaction of the alkenyl group in component (A) and the silicon atom in component (B).

[0104] As component (F), namely, the platinum catalyst compound activated by ultraviolet light, the acetylacetone platinum complex, cyclopentadienyl platinum complex, etc., as shown in U.S. Patent No. 4,510,094 (Patent Document 8) and U.S. Patent No. 4,530,879 (Patent Document 9) are used.

[0105] As a specific example of such a (F) component, (η) can be listed. 5 Complexes of trialiphatic platinum compounds (-cyclopentadienyl). Preferably, cyclopentadienyltrimethylplatinum complex and methylcyclopentadienyltrimethylplatinum complex are preferred.

[0106] In addition, complexes of bis(β-diketone)platinum compounds can be listed. Among them, bis(acetylacetone)platinum complexes are preferred.

[0107] When blending the platinum catalyst compound containing component (F), the amount blended relative to the total mass of components (A) and (B) is preferably 0.1 to 1000 ppm, more preferably 0.1 to 500 ppm, and even more preferably 0.1 to 50 ppm, calculated by the mass of platinum atoms contained in component (F). If the amount blended in component (F) is less than the above range, the curing reaction rate may be insufficient, or it may become uncured due to the influence of surrounding curing-inhibiting factors. If the amount blended in component (F) is greater than the above range, sufficient preservation may not be obtained.

[0108] (F) Components can be used alone or in combination of two or more.

[0109] Furthermore, when using component (F), if it is a solid catalyst, it can also be used in solid form. To obtain a more uniform solidified product, it is preferable to dissolve the catalyst in a suitable solvent such as toluene, xylene, ethyl acetate, or 2-(2-butoxyethoxy)ethyl acetate. In this case, the platinum atom content (concentration) in the solution is preferably 0.1 to 2% by mass.

[0110] (G) Photoinitiator

[0111] Furthermore, in the curable liquid silicone composition of the present invention, as an optional component, in the platinum catalyst mixture of component (C), it is also useful to mix in the photoinitiator of component (G) in order to reduce the control ability of the phosphite compound on the platinum catalyst.

[0112] As described above, the phosphite compound in the curable liquid organosilicon composition of the present invention is hydrolyzed by atmospheric moisture to become phosphonic acid, thereby reducing the controllability of the platinum catalyst. During curing, by adding the photoinitiator of component (G) and irradiating with ultraviolet light, the phosphite compound is oxidized by the peroxy radicals formed by the free radicals generated by the photoinitiator and oxygen, which also reduces the controllability of the platinum catalyst.

[0113] As component (G), i.e., the photoinitiator, photoinitiators conventionally used in UV-curable liquid silicone compositions can be used. Specifically, examples include acetophenone, phenylacetone, benzophenone, fluorescein, benzaldehyde, anthraquinone, triphenylamine, carbazole, 3-methylacetophenone, 4-methylacetophenone, 3-pentylacetophenone, 4-methoxyacetophenone, 3-bromoacetophenone, 4-allylacetophenone, p-diacetylbenzene, 3-methoxybenzophenone, 4-methylbenzophenone, 4-chlorobenzophenone, 4,4'-dimethoxybenzophenone, 2,2'-diethoxyacetophenone, 4-chloro-4'-benzylbenzophenone, 3-chloroxanthone, 3,9-dichloroxanthone, 3-chloro-8-nonylxanthone, benzoin, and benzoin methyl. Benzyl ether, benzoin butyl ether, bis(4-dimethylaminophenyl) ketone, benzyl methoxy ketal, 2-chlorothioxanone, diethyl acetophenone, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1[4-(methylthio)phenyl]-2-morpholino-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone, 1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propane-1-one, 2,2-dimethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropane-1-one, cyclohexylphenyl ketone, 2-hydroxy-2-methylphenylacetone, etc.

[0114] When used as a photoinitiator in the formulation of component (G), the preferred amount is 0.01 to 3% by mass of the total mass of components (A) and (B), more preferably 0.01 to 1% by mass, and even more preferably 0.01 to 0.1% by mass. If the amount of component (G) is less than the above range, its additive effect may not be present, and if the amount is more than the above range, sufficient preservation may not be achieved.

[0115] In the curable liquid silicone composition of the present invention, in addition to the optional components such as (E) dehydrating agent, (F) platinum catalyst compound that can be activated by ultraviolet light, and (G) photoinitiator, inorganic fillers, adhesive agents, pigment pastes, and reinforcing silicone resins can be mixed as other optional components as needed, without prejudice to the purpose of the present invention.

[0116] The curable liquid silicone composition of the present invention can be prepared by mixing the above-mentioned components (A) to (D) and other components that may be used as needed according to conventional methods. Preferably, it is added while mixing in the following order: (A) alkenyl-containing diorganopolysiloxane, (B) organohydrogen polysiloxane, (D) hydrolysis reaction catalyst, and (C) platinum catalyst mixture. Furthermore, when adding the dehydrating agent of component (E), it is preferable to add it after adding (B) organohydrogen polysiloxane, and then after adding (D) hydrolysis reaction catalyst, seal the container and cure it under a nitrogen atmosphere for one night or longer before adding (C) platinum catalyst mixture. In addition, when adding the platinum catalyst compound that can be activated by ultraviolet light of component (F) and / or the photoinitiator of component (G), it is preferable to use a shielded container and add it after adding (C) platinum catalyst mixture.

[0117] The curable liquid silicone composition according to the present invention, when stored in a highly airtight container capable of blocking or reducing the intrusion of moisture, particularly atmospheric moisture (humidity) (wherein, in the case of component (F), ultraviolet light is blocked and the intrusion of moisture, particularly atmospheric moisture (humidity) is blocked and reduced; furthermore, in the case of component (G), ultraviolet light is blocked and the intrusion of oxygen and moisture, particularly atmospheric moisture (humidity) and oxygen is blocked and reduced), achieves superior single-component preservation properties. Therefore, it is possible to distribute and market this single-component curable liquid silicone composition.

[0118] Furthermore, the curable liquid silicone composition of the present invention cures at room temperature using atmospheric moisture (however, in the case of containing component (F), it cures by irradiating with ultraviolet light, and then by exposing to the atmosphere, where it comes into contact with atmospheric moisture (humidity) at room temperature, thereby curing even dark areas not reached by ultraviolet light; in addition, in the case of containing component (G), it cures by irradiating with ultraviolet light, and then by exposing to the atmosphere, where it comes into contact with atmospheric moisture (humidity) and oxygen at room temperature), thus forming a silicone rubber cured product or a silicone gel cured product.

[0119] The UV irradiation method for the curable liquid silicone composition of the present invention involves irradiating it with UV light at room temperature (23°C ± 15°C), preferably with light of 200–500 nm at room temperature, when the composition contains component (F) is activated by UV irradiation. In the case containing component (F), the platinum catalyst compound of component (F) in the UV-irradiated portion is activated by UV irradiation, acting as a catalyst for the hydrosilylation addition reaction, promoting the hydrosilylation addition reaction, and thus curing. Alternatively, in the case containing component (G), free radicals are generated from the photoinitiator of component (G) by UV irradiation. These free radicals combine with oxygen in the atmosphere to become peroxy radicals, oxidizing the phosphite compound, thereby activating the platinum catalyst in component (C), which acts as a catalyst for the hydrosilylation addition reaction, promoting the hydrosilylation addition reaction, and thus curing.

[0120] There are no particular limitations on lamps that can supply light with a wavelength of 200–500 nm. Examples include low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, xenon lamps, metal halide lamps, and ultraviolet LED lamps. The amount of ultraviolet irradiation varies depending on the type and amount of platinum catalyst compound (F) and photoinitiator (G) used, but is preferably 10–1000 mW / cm². 2 Especially 20–400 mW / cm 2 Exposure to ultraviolet radiation for 0.1 seconds to 5 minutes, especially 0.5 seconds to 1 minute.

[0121] The curable liquid silicone composition of the present invention has good curability even in dark areas where ultraviolet light does not reach. Therefore, when the curable composition is cured by ultraviolet irradiation, it is suitable for use as a sealant, coating agent, liquid optically clear adhesive (LOCA), etc., for components with a large number of complex dark areas.

[0122] Example

[0123] The following examples and comparative examples illustrate the invention in more detail, but the invention is not limited to the examples described below. Furthermore, in the examples below, viscosity is the value measured using a rotational viscometer at 23°C, and parts represent parts by mass. "Room temperature" means 23°C.

[0124] [Comparative Example 1, Examples 1-4]

[0125] A curable liquid silicone composition was prepared according to the following instructions.

[0126] <Preparation of Curable Liquid Organosilicon Compositions>

[0127] Under a nitrogen atmosphere at room temperature (23°C), the components were uniformly mixed in brown glass bottles at the mixing amounts shown in Table 1. The bottles were then kept dark and sealed to prepare the compositions. It should be noted that the molar ratio of SiH groups in component (B) to vinyl groups in component (A) is 1.1.

[0128] For the addition at this time, the following steps are taken: (A) diorganopolysiloxane containing alkenyl groups, (B) organohydrogen polysiloxane, (E) dehydrating agent, (D) hydrolysis reaction catalyst, and (C) a mixture of platinum catalysts containing platinum catalysts and phosphite compounds, and the addition is carried out while mixing.

[0129] Furthermore, in the case of adding the dehydrating agent containing component (E), after adding the hydrolysis reaction catalyst (D), the amber glass bottle is sealed and aged under a nitrogen atmosphere overnight or longer, and then the platinum catalyst mixture (C), containing a platinum catalyst and a phosphite compound, is added. Moreover, in the case of adding not only the dehydrating agent containing component (E) but also a platinum catalyst compound that can be activated by ultraviolet light (component (F)) and / or a photoinitiator (component (G),) the platinum catalyst mixture (C), containing a platinum catalyst and a phosphite compound, is added.

[0130] It should be noted that the ingredients are as follows.

[0131] (A) Alkenyl-containing diorganopolysiloxanes:

[0132] The vinyl-containing branched dimethyl polysiloxane with a viscosity of 1000 mPa·s at 23°C, expressed by the following average formula (4).

[0133] [Chemistry 4]

[0134]

[0135] (B) Organohydrogen polysiloxanes:

[0136] The linear methylhydrosiloxane (dimethylhydrosiloxy-terminated dimethylpolysiloxane) represented by the following average formula (5)

[0137] [Chemistry 5]

[0138]

[0139] (C) A mixture of platinum catalysts containing platinum catalysts and phosphite compounds:

[0140] Under a nitrogen atmosphere, a platinum catalyst mixture containing 1.05 moles of triisopropyl phosphite relative to 1 mole of platinum atoms was prepared in a platinum-divinyltetramethyldisiloxane complex / toluene solution (platinum atom content 0.5% by mass).

[0141] (D) Hydrolysis reaction catalyst:

[0142] Tetra(isopropyl) titanate (TPT)

[0143] (E) Dehydrating agent:

[0144] 2-(trimethoxysilyl)propionate ethyl ester (ECMS) (α-silyl ester)

[0145] (F) Platinum catalyst compounds activated by ultraviolet light:

[0146] A toluene solution of methylcyclopentadienyltrimethylplatinum complex (platinum atom content 0.5% by mass)

[0147] (G) Photoinitiator:

[0148] Darocure 1173 (2-hydroxy-2-methylphenylacetone) manufactured by BASF Japan Co., Ltd.

[0149] In the prepared curable liquid silicone composition, the cured product appearance, single-component preservation under light-shielding, airtight, and room temperature conditions, moisture (aerobic) curing properties under light-shielding, atmospheric, and room temperature conditions, and shadow curing properties under ultraviolet irradiation were evaluated as follows.

[0150] [Appearance of cured product]

[0151] The appearance of the cured products was evaluated visually; all examples and comparative examples were colorless to brownish-transparent. The evaluation results are shown in Table 1.

[0152] [Single-component preservation (protected from light, sealed, at room temperature)]

[0153] Regarding the single-component preservation, the curing liquid silicone composition was filled into a brown glass bottle under a nitrogen atmosphere, sealed, and then placed in the atmosphere / room temperature. The thickening and gelling behavior of the curing liquid silicone composition was observed. At this time, regarding the thickening and gelling behavior of the curing liquid silicone composition, the degree to which the composition in the brown glass bottle followed its flow (flowability) was observed when the bottle was tilted. A decrease in flowability compared to when it was immediately sealed was judged as thickening or gelling of the curing liquid silicone composition. This was confirmed weekly, and weeks in which thickening or gelling was confirmed are recorded in Table 1.

[0154] [Moisture (Aerobic) Curing Properties (Under Shading, Atmospheric Conditions, Room Temperature)]

[0155] Regarding moisture curing properties, the curing liquid silicone composition was filled into a brown glass bottle under a nitrogen atmosphere and sealed. After 3 hours, 9g of the curing liquid silicone composition was injected from the brown glass bottle into a glass dish with an inner diameter of 10mm. The dish was then covered with aluminum foil and kept dark under atmospheric and room temperature conditions. The results were observed after one week and are shown in Table 1.

[0156] [Shadow curing properties under ultraviolet irradiation]

[0157] 9g (approximately 3.2mm thick) of each of the above-prepared compositions were filled into a circular aluminum dish with an inner diameter of 60mm. A light-shielding plate with concentric holes (gaps) of 20mm diameter from the center was then placed on top. Using an ultraviolet irradiation device (manufactured by CCS Corporation) with a UV-LED lamp as the light source, irradiation with 365nm ultraviolet light at room temperature (23°C) was performed at an irradiation dose of 8000mJ / cm². 2 It is cured by irradiating it with ultraviolet light. A schematic diagram is shown below. Figure 1 In this diagram, 1 is an aluminum dish, 2 is a curable liquid silicone composition, 3 is a light-shielding plate, 4 is a hole (gap) in the light-shielding plate, and 5 is the direction of ultraviolet irradiation.

[0158] For each composition, the liquid portion was removed after 10 minutes, 24 hours, and 72 hours of UV irradiation, and the size from the outer periphery of the light-receiving portion to the cured gel end was defined as the cured shadow portion size, and the results were evaluated. A schematic diagram is shown below. Figure 2 In this table, 6 represents the cured portion (20 mm in diameter) of the UV-exposed area directly irradiated with ultraviolet light; 7 represents the cured portion of the shadow area covered by a shielding plate and not exposed to ultraviolet light; 8 represents the uncured portion of the shadow area covered by a shielding plate and not exposed to ultraviolet light; and 9 represents the cured size of the shadow area as measured and evaluated above. It should be noted that the maximum cured size of the shadow area in this evaluation is 20 mm. The results are shown in Table 1.

[0159] [Table 1]

[0160]

[0161] The above results confirm that the curable liquid silicone composition of the present invention exhibits single-component preservation at room temperature in a sealed container and cures at room temperature without heating by utilizing atmospheric moisture.

[0162] Explanation of reference numerals in the attached figures

[0163] 1 Aluminum dish

[0164] 2. Curable liquid silicone composition

[0165] 3 visor

[0166] 4. Holes (gap) in the light-shielding plate (diameter 20mm)

[0167] 5. Direction of ultraviolet radiation

[0168] 6. Ultraviolet light-receiving part (diameter 20mm)

[0169] 7. Image curing section

[0170] 8 Uncured areas of the shadow

[0171] 9. Curing dimensions of the shadow area

Claims

1. A curable liquid silicone composition, comprising: (A) A linear or branched diorganopolysiloxane having at least one alkenyl group in one molecule, (B) A linear or branched organohydrogen polysiloxane having at least two hydrogen atoms bonded to silicon atoms in one molecule: in such amounts that, relative to 1 mole of alkenyl group in component (A), the number of hydrogen atoms bonded to silicon atoms in component (B) is 0.5 to 4 moles. (C) A platinum catalyst mixture comprising a platinum catalyst and a phosphite compound in an amount of 0.5 to 3 moles relative to 1 mole of platinum atoms: the amount being such that, converted from the mass of platinum atoms in component (C) relative to the total mass of components (A) and (B), it is 0.1 to 1000 ppm. (D) Hydrolysis catalyst: 0.01 to 3% of the total mass of components (A) and (B).

2. The curable liquid silicone composition according to claim 1 is a single-component type.

3. The curable liquid silicone composition according to claim 1, further comprising (E) a dehydrating agent: 0.01 to 5% by mass of the total mass of components (A) and (B).

4. The curable liquid silicone composition according to claim 1, further comprising (F) a platinum catalyst compound that can be activated by ultraviolet light, wherein the amount is such that, calculated as the mass of platinum atoms in component (F) relative to the total mass of components (A) and (B), it is 0.1 to 1000 ppm.

5. The curable liquid silicone composition according to claim 1, further comprising (G) a photoinitiator: 0.01 to 3% by mass of the total mass of components (A) and (B).

6. The cured product of the curable liquid silicone composition according to any one of claims 1 to 5.

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