Photocurable organopolysiloxane composition and cured product thereof

Abstract

The present invention provides an organopolysiloxane composition having curability suitable for stereolithography and storage stability sufficient for ensuring workability.　The present invention pertains to a photocurable organopolysiloxane composition comprising: (A) (A-i) and / or (A-ii), with (A-i) being a linear organopolysiloxane having an alkenyl group, which is bonded to a silicon atom, at both terminals, and (A-ii) being an organopolysiloxane resin having an [SiO4 / 2] unit; (B) an organopolysiloxane not having an [SiO4 / 2] unit; (C) an organohydrogenpolysiloxane having two or more hydrosilyl groups in one molecule; (D) a photoactive hydrosilylation reaction catalyst; (E) a polyether and / or a polyether derivative; and (F) silica that has a BET specific surface area of 50 to 400 m2 / g and is such that the surface has undergone a hydrophobizing treatment.

Description

Photocurable organopolysiloxane composition and its cured product

[0001] The present invention relates to a photocurable organopolysiloxane composition that can be cured by a hydrosilylation reaction, and more specifically, to a photocurable organopolysiloxane composition suitable as a 3D printer material, and to a cured product made therefrom.

[0002] Silicone rubber is widely used in various fields due to its excellent heat resistance, cold resistance, and electrical properties. Furthermore, because silicone rubber is more flexible than general-purpose plastics such as acrylic resin, it is also used as a base material for models of the human body and organs. In this field, silicone resin is being applied as a shape-forming material for 3D printing, enabling the precise manufacturing of complex shapes without the need for molds.

[0003] One method for manufacturing silicone molded parts using stereolithography involves using (meth)acrylic-modified silicone resin obtained through photopolymerization by radicals. However, this method suffers from the problem of curing inhibition by oxygen. Furthermore, because the (meth)acrylic group is highly reactive, crosslinking occurs not only in the light-irradiated areas but also in the non-irradiated areas, making it difficult to achieve high dimensional accuracy. In particular, in additive stereolithography, adding UV absorbers or light-shielding pigments is effective in controlling the reactivity in the non-irradiated areas, but this impairs the inherent high transparency of the silicone resin, thus limiting its applications.

[0004] Therefore, attempts have been made to solve the above-mentioned problems by utilizing an addition curing reaction using a platinum catalyst. Patent documents 1 and 2 describe a method of heating after each layer has been deposited. However, with this method, the silicone resin softens before it hardens due to heating, resulting in distortion or collapse of the laminate structure, making it impossible to guarantee accurate dimensional precision.

[0005] Furthermore, a method using a silicone composition containing a platinum catalyst activated by irradiation with high-energy rays such as ultraviolet light has been investigated. This method does not require heating for curing, thus potentially guaranteeing high dimensional accuracy. On the other hand, the photoactive platinum catalyst used in such silicone compositions is a platinum complex with ligands, and since the ligands of the platinum complex detach over time, the curing reaction proceeds gradually even without light irradiation, which presents a problem in that a sufficient working time (pot life) cannot be maintained. Adding a reaction control agent to the silicone composition makes it possible to ensure a pot life, but it becomes difficult to obtain the required curability.

[0006] Patent Document 3 describes a method for solving the above-mentioned storage stability problem by using an organopolysiloxane with an alkenyl group content within a specific range and a specific organohydrogensiloxane. Patent Document 4 describes a method for solving the above-mentioned storage stability problem by using silica particles surface-treated with a mixture of an organopolysiloxane having alkenyl groups and hexamethyldisilazane. However, it is difficult to say that any of these silicone compositions achieve both sufficient curability and storage stability.

[0007] International Publication No. 2020 / 082359, International Publication No. 2017 / 040874, International Publication No. 2023 / 112925, Japanese Patent Publication No. 2019-014801

[0008] Therefore, the present invention aims to provide an organopolysiloxane composition that contains silica particles and has curability suitable for stereolithography, as well as sufficient storage stability to ensure workability.

[0009] The inventors of the present invention have conducted extensive research to solve the above problems and have found that an organopolysiloxane composition containing silica particles with a hydrophobically treated surface and a hydrocarbon-based polyoxyalkylene compound not only has the curability necessary for photopolymerization but also has storage stability that allows for sufficient working time, thus completing the present invention. In other words, the present invention provides the following photocurable organopolysiloxane composition and its cured product.

[0010] [1] (A) The following (A-i) and / or (A-ii), (A-i) [R 1 2R 2 SiO 1 / 2 unit and [R 1 2SiO 2 / 2 unit and / or [R 1 R 2 SiO 2 / 2 unit (R 1 is independently an unsubstituted or halogen-substituted monovalent hydrocarbon group having no aliphatic unsaturated bond, and R 2 is an alkenyl group.) consisting of a linear organopolysiloxane (A-ii) [R 1 2R 2 SiO 1 / 2 unit (R 1 is independently an unsubstituted or halogen-substituted monovalent hydrocarbon group having no aliphatic unsaturated bond, and R 2 is an alkenyl group.) and an organopolysiloxane resin having a [SiO 4 / 2 unit (B) [R 1 2R 2 SiO 1 / 2 unit and [R 1 SiO 3 / 2 unit (R 1 is independently an unsubstituted or halogen-substituted monovalent hydrocarbon group having no aliphatic unsaturated bond, and R 2 is an alkenyl group.), and having no [SiO 4 / 2 unit, an organopolysiloxane, (C) an organohydrogenpolysiloxane having two or more hydrosilyl groups in one molecule, (D) a photoactive hydrosilylation reaction catalyst, (E) a polyether and / or a polyether derivative, and (F) a BET specific surface area of 50 to 400 m 2[1] A photocurable organopolysiloxane composition comprising silica at a concentration of / g and having a hydrophobic surface treatment. [2] The photocurable organopolysiloxane composition according to [1], wherein component (D) is a photoactive platinum complex having a β-diketone compound or a cyclic diene compound as a ligand. [3] The photocurable organopolysiloxane composition according to [1] or [2], wherein component (E) has a linear or branched alkylene group having 2 to 4 carbon atoms in the main chain. [4] The photocurable organopolysiloxane composition according to any one of [1] to [3] for use as a 3D printer molding material. [5] A cured product of the photocurable organopolysiloxane composition according to any one of [1] to [3].

[0011] The photocurable organopolysiloxane composition of the present invention has high storage stability when uncured, and after irradiation with energy rays such as ultraviolet light, it cures rapidly at room temperature. Having these properties, the photocurable organopolysiloxane composition of the present invention is useful as a material for stereolithography such as 3D printing, and in particular as a material for LAM (liquid deposition modeling) 3D printers.

[0012] The present invention will be described in more detail below. The photocurable organopolysiloxane composition according to the present invention contains the following components (A) to (F).

[0013] [Component (A)] Component (A) is the following (A-i) alkenyl group-containing linear organopolysiloxane and / or (A-ii) organopolysiloxane resin.

[0014] (A-i) Alkenyl group-containing linear organopolysiloxane. Component (A-i) is [R 1 2R 2 SiO 1 / 2 ] Units and [R 1 2SiO 2 / 2 ] Units and / or [R 1 R 2 SiO 2 / 2 ] Unit (R 1 R is an unsubstituted or halogen-substituted monovalent hydrocarbon group that does not independently have an aliphatic unsaturated bond, 2 It is a linear organopolysiloxane consisting of an alkenyl group and a linear organopolysiloxane.

[0015] R 1 Examples of monovalent hydrocarbon groups include unsubstituted or substituted monovalent hydrocarbon groups that do not contain aliphatic unsaturated bonds and have preferably 1 to 12, more preferably 1 to 10, carbon atoms. Examples of unsubstituted or substituted monovalent hydrocarbon groups include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, nonyl, and decyl groups; cycloalkyl groups such as cyclohexyl groups; aryl groups such as phenyl, tolyl, xylyl, and naphthyl groups; aralkyl groups such as benzyl and phenethyl groups; and halogenated alkyl groups such as chloromethyl, 3-chloropropyl, and 3,3,3-trifluoropropyl groups, in which some or all of the hydrogen atoms of these groups are substituted with halogen atoms such as chlorine, fluorine, or bromine atoms. Preferably, alkyl groups and aryl groups are preferred, and more preferably, methyl and phenyl groups are preferred.

[0016] R 2 Examples of alkenyl groups include groups having 2 to 10 carbon atoms, preferably 2 to 6 carbon atoms, such as vinyl groups, allyl groups, propenyl groups, isopropenyl groups, butenyl groups, isobutenyl groups, pentenyl groups, hexenyl groups, cyclohexenyl groups, and heptenyl groups, with vinyl groups being particularly preferred.

[0017] The bond position of the alkenyl group is, [R 1 2R 2 SiO 1 / 2 Molecular chain ends and [R] expressed in units of ] 1 R 2 SiO 2 / 2 It may be both the non-terminal (i.e., side chain) of the molecular chain represented in units of [R], but only both terminals are preferred. That is, component (A-i) is [R 1 2R 2 SiO 1 / 2 ] Units and [R 1 2SiO 2 / 2 It is preferable that it consists only of units.

[0018] In component (A-i), the content of alkenyl groups bonded to the silicon atoms is preferably 0.001 to 10 moles, and particularly preferably 0.001 to 1 mole, per 100 g of the component. The content of silicon atom-bonded alkenyl groups is 29 It can be measured by Si-NMR.

[0019] The viscosity of component (A-i) at 25°C is preferably 100 to 500,000 mPa·s, and particularly preferably 300 to 100,000 mPa·s, from the viewpoint of the workability of the composition and the reinforcing effect of the resulting cured product. In this invention, viscosity can be measured by a rotational viscometer (e.g., BL type, BH type, BS type, cone plate type, rheometer, etc.) (the same applies hereinafter). Also, for similar reasons, the number of silicon atoms (or degree of polymerization) in component (A-i) is preferably 50 to 1,500, more preferably 100 to 1,000, and particularly preferably 120 to 800. In this invention, the degree of polymerization (or molecular weight) can be determined, for example, by the weight-average degree of polymerization (or weight-average molecular weight) in polystyrene terms in gel permeation chromatography (GPC) analysis using toluene or the like as the developing solvent (the same applies hereinafter).

[0020] Component (A-i) may be used alone or in combination of two or more types.

[0021] (A-ii) Organopolysiloxane resin (A-ii) component is [R 1 2R 2 SiO 1 / 2 ] units and [SiO 4 / 2 It is an organopolysiloxane resin in which the ] unit is an essential constituent unit. Here, R 1 R is an unsubstituted or halogen-substituted monovalent hydrocarbon group that does not independently have an aliphatic unsaturated bond, 2 This is an alkenyl group.

[0022] R 1 Specific examples of the monovalent hydrocarbon group include the same groups as those exemplified in component (A-i) above, preferably a methyl group and a phenyl group. Multiple R groups contained in component (A-ii) 1They may be the same or different, but from the viewpoint of compatibility with other components, R 1 It is preferable that 80 mol% or more of the group consists of methyl groups.

[0023] R 2 Specific examples of the alkenyl group include the same group as exemplified in component (A-i) above, and it is preferably a vinyl group.

[0024] (A-ii) component is [R 1 2R 2 SiO 1 / 2 ] units and [SiO 4 / 2 In addition to the units, [R 1 3SiO 1 / 2 ] Unit [R 1 2SiO 2 / 2 ] Unit [R 1 R 2 SiO 2 / 2 ] Unit [R 1 SiO 3 / 2 ] Unit [R 2 SiO 3 / 2 It may include units, etc.

[0025] [R in component (A-ii)] 1 2R 2 SiO 1 / 2 ] and [R 1 3SiO 1 / 2 The M units represented by [SiO] and [SiO] 4 / 2 The molar ratio (M units / Q units) of M units to Q units, as expressed by [ ], is preferably 0.6 to 1.2 moles of M units per 1 mole of Q units, and more preferably 0.8 to 1.0 moles of M units. If the molar ratio (M units / Q units) is 0.6 or higher, gelation of the composition can be suppressed, and if it is 1.2 or lower, sufficient crosslinking is achieved, resulting in an improvement in the hardness of the cured product. Furthermore, the proportion of M units and Q units in the total constituent units of component (A-ii) is preferably 80 mol% or higher, and more preferably 90 mol% or higher.

[0026] Specific examples of component (A-ii) include copolymers of vinyldimethylsiloxane units and Q units, copolymers of vinyldimethylsiloxane units, trimethylsiloxane units and Q units, copolymers of vinyldimethylsiloxane units, dimethyldisiloxane units and Q units, copolymers of vinyldimethylsiloxane units, phenyltrisiloxane units and Q units, copolymers of vinyldimethylsiloxane units, dimethyldisiloxane units, phenyltrisiloxane units and Q units, and copolymers of trimethylsiloxane units, vinylmethyldisiloxane units and Q units.

[0027] In component (A-ii), the content of the alkenyl group is preferably 0.001 to 10 moles, and particularly preferably 0.001 to 1 mole, per 100 g of the component.

[0028] The weight-average molecular weight of component (A-ii), as determined by gel permeation chromatography (GPC) with polystyrene as the standard substance, is preferably 2,000 to 8,000, and particularly preferably 4,000 to 6,000, which is normally solid at 25°C.

[0029] Component (A-ii) may be used alone or in combination of two or more types.

[0030] The mixing ratio of component (A-i) and component (A-ii) in component (A) is preferably in the range of 50:50 to 95:5, and more preferably in the range of 70:30 to 90:10, in terms of the mass ratio of component (A-i) to component (A-ii).

[0031] The content of component (A) in the composition is preferably 50 to 95% by mass of the total composition, and more preferably 70 to 90% by mass.

[0032] [Component (B)] Component (B) is [R 1 2R 2 SiO 1 / 2 ] Units and [R 1 SiO 3 / 2 ] Unit (R 1 R is an unsubstituted or halogen-substituted monovalent hydrocarbon group that does not independently have an aliphatic unsaturated bond, 2is an alkenyl group.) and has no [SiO 4 / 2 unit, and acts as a reinforcing agent in the photocurable organopolysiloxane composition of the present invention. Component (B) is clearly distinguished from the organopolysiloxane resin of component (A-ii) above in that it does not contain [SiO 4 / 2 units in its molecule.

[0033] Component (B) may contain, in addition to [R 1 2R 2 SiO 1 / 2 units and [R 1 SiO 3 / 2 units, [R 1 3SiO 1 / 2 units, [R 1 2SiO 2 / 2 units, [R 1 R 2 SiO 2 / 2 units, [R 2 SiO 3 / 2 units, etc.

[0034] The molar ratio (M unit / T unit) of the M unit represented by [R 1 2R 2 SiO 1 / 2 and [R 1 3SiO 1 / 2 to the T unit represented by [R 1 SiO 3 / 2 and [R 2 SiO 3 / 2 in component (B) is preferably 0.1 to 10 moles of M unit per 1 mole of T unit, and more preferably 0.5 to 5 moles.

[0035] From the viewpoints of the curability of the composition and the reinforcing effect of the resulting cured product, the amount of the alkenyl group contained in component (B) is preferably 0.01 to 5 moles, more preferably 0.02 to 2 moles, per 100 g of this component. Also, the viscosity of component (B) measured by a rotational viscometer at 25 °C is preferably within the range of 1 to 1,000 mPa·s, and more preferably within the range of 10 to 100 mPa·s.

[0036] Component (B) can be prepared by known methods. For example, it can be easily obtained by stirring at a temperature of 50°C or less in the presence of sulfuric acid, trifluoromethanesulfonic acid, or methanesulfonic acid catalyst, and then adding water dropwise at a temperature of 65°C or less to co-hydrolyze and condense the hydrolyzed product of methyltrichlorosilane with water-methanol, tetramethyldivinyldisiloxane, and optionally hexamethyldisiloxane in the presence of sulfuric acid, trifluoromethanesulfonic acid, or methanesulfonic acid catalyst.

[0037] (B) Component may be used alone or in combination of two or more types.

[0038] From the viewpoint of the curability of the composition and the reinforcing effect of the resulting cured product, the amount of component (B) is preferably 0.01 to 10 parts by mass, and more preferably 0.1 to 5 parts by mass, per 100 parts by mass of component (A).

[0039] [Component (C)] Component (C) is an organohydrogenpolysiloxane having two or more hydrosilyl groups (SiH groups) in one molecule, and plays the role of a crosslinking agent that forms a crosslinked structure with components (A) and (B) through a hydrosilylation reaction.

[0040] The molecular structure of component (C) is not particularly limited and can be linear (i.e., the main chain basically consists of repeating diorganosiloxane units), cyclic, branched (linear with some branching), or dendrimer, with linear or branched structures being preferred. Alternatively, it may be a single polymer having these molecular structures, a copolymer consisting of these molecular structures, or a mixture of these polymers.

[0041] (C) Specifically, the component has an average structure represented by the following formula (1). 3 a H b SiO (4-a-b) / 2 (1) (In formula (1), R 3 (where a is a monovalent hydrocarbon group having 1 to 10 carbon atoms that does not independently have an aliphatic unsaturated bond, and a is a number between 0.7 and 2.1, b is a number between 0.001 and 1.0, and satisfies 0.8 ≤ a + b ≤ 3.0.)

[0042] In the above formula (1), a is preferably a number between 1.0 and 1.8, b is preferably a number between 0.1 and 1, and a + b is preferably 1.1 ≤ a + b ≤ 2.4, more preferably 1.6 ≤ a + b ≤ 2.2. Within this range, foaming during curing can be suppressed, the hardness of the resulting cured product is further improved, and changes in hardness over time are less likely to occur.

[0043] The kinematic viscosity of component (C) at 23°C is 0.5 to 200 mm². 2 / s is preferred, and 1 to 50 mm 2 / s is more preferable. Here, the kinematic viscosity is measured using a Cannon-Fenske viscometer.

[0044] The amount of hydrosilyl groups (SiH groups) in component (C) is preferably 0.001 to 0.020 mol / g, and more preferably 0.002 to 0.015 mol / g. In this invention, the amount of hydrosilyl groups is determined by measuring the volume of hydrogen gas generated per unit mass of organohydrogenpolysiloxane by alkaline decomposition.

[0045] Component (C) may be used alone or in combination of two or more types.

[0046] The amount of component (C) is preferably such that the ratio of the number of hydrosilyl groups to the number of alkenyl groups in the composition is in the range of 0.3 to 3.0, and more preferably in the range of 0.5 to 2.0. If the ratio of the number of hydrosilyl groups to the number of alkenyl groups in the composition is 0.3 or higher, sufficient curability is achieved, and if it is 3.0 or lower, foaming during curing can be suppressed.

[0047] [Component (D)] Component (D) is a photoactive hydrosilylation catalyst that exhibits activity upon irradiation with high-energy rays such as ultraviolet light and promotes the addition reaction between the alkenyl groups in components (A) and (B) and the hydrosilyl groups in component (C). Examples of such photoactive catalysts include β-diketone compounds such as bis(2,4-pentanedionato)platinum(II) complex and trimethyl(acetylacetonato)platinum(IV) complex, or photoactive platinum complexes having cyclic diene compounds such as (methylcyclopentadienyl)trimethylplatinum(IV) complex and (1,2,3,4,5-pentamethylcyclopentadienyl)trimethylplatinum(IV) complex as ligands.

[0048] The amount of component (D) should be such that it promotes the hydrosilylation reaction, but preferably it is such that, relative to the total of components (A), (B), and (C), the mass of the metal in component (D) is in the range of 0.01 to 500 ppm, more preferably it is in the range of 0.05 to 100 ppm, and even more preferably it is in the range of 0.01 to 50 ppm.

[0049] [Component (E)] Component (E) is a polyether and / or polyether derivative, preferably having a linear or branched alkylene group with 2 to 4 carbon atoms in the main chain. Component (E), when used together with the silica-based filler component (F) described later, imparts thixotropy to the photocurable organopolysiloxane composition, suppressing sagging during the uncured state and enabling shape retention.

[0050] Specific examples of such polyethers and polyether derivatives include polyoxyalkylenes, alkylene oxide copolymers, polyoxyalkylene alkyl ethers, polyoxyalkylene alkenyl ethers, alkyl ethers of alkylene oxide copolymers, polyoxyalkylene fatty acid esters, and alkylene oxide copolymer fatty acid esters. More specifically, examples include polyoxyethylene, polyoxypropylene, polyoxyisopropylene, polyoxybutylene, polyoxyisobutylene, polyoxytrimethylene, polyoxytetramethylene, ethylene oxide-propylene oxide copolymer, ethylene oxide-butylene oxide copolymer, ethylene oxide-trimethylene oxide copolymer, ethylene oxide-tetramethylene oxide copolymer, propylene oxide-butylene oxide copolymer, polyoxyethylene monoethyl ether, polyoxyethylene diethyl ether, polyoxyethylene monoallyl ether, polyoxyethylene diallyl ether, polyoxypropylene monoethyl ether, polyoxypropylene diethyl ether, polyoxypropylene monoallyl ether, polyoxypropylene diallyl ether, polyoxybutylene monomethyl ether, ethylene oxide-propylene oxide copolymer monobutyl ether, ethylene oxide-propylene oxide copolymer dibutyl ether, ethylene oxide-propylene oxide copolymer monoallyl ether, polyoxyethylene monolaurate, and polyoxyethylene monostearate. Among these, those in which the alkylene group constituting the main chain is a linear or branched alkylene group having 2 to 4 carbon atoms are preferred, and ethylene oxide-propylene oxide copolymer, ethylene oxide-propylene oxide copolymer monobutyl ether, ethylene oxide-propylene oxide copolymer dibutyl ether, polyoxypropylene monoallyl ether, and polyoxypropylene diallyl ether are particularly preferred because they can impart thixotropy to the composition with the addition of relatively small amounts.Furthermore, NOF Corporation's Uniox® M series, Uniox® PKA series, Uniol® D series (polyoxyalkylene), Uniol® PB series, Unisafe® PKA series, Unilube® series, and Polycerin® series (alkylene oxide copolymer) can also be suitably used.

[0051] Component (E) is preferably in liquid form from the viewpoint of dispersibility in the photocurable organopolysiloxane composition and thixotropic effect. Its molecular weight can be appropriately selected and used based on its properties.

[0052] (E) Component may be used alone or in combination of two or more types.

[0053] From the viewpoint of achieving both thixotropy and workability of the composition, the amount of component (E) is preferably in the range of 0.001 to 10 parts by mass, more preferably in the range of 0.005 to 5 parts by mass, and particularly preferably in the range of 0.01 to 1 part by mass, per 100 parts by mass of component (A).

[0054] [Component (F)] Component (F) has a BET specific surface area of ​​50 to 400 m². 2 This silica has a density of / g and a surface that has been hydrophobically treated, and can impart appropriate mechanical properties to the cured product obtained from the photocurable organopolysiloxane composition of the present invention. Furthermore, when used together with the aforementioned component (E), it can impart thixotropy to the photocurable organopolysiloxane composition.

[0055] This silica-based filler has a BET specific surface area of ​​50 to 400 m². 2 / g, preferably 100 to 350m 2 A fine silica powder with a density of 1 / g that has been hydrophobized is preferred. The BET specific surface area is 50 m². 2 If the amount is less than / g, the resulting cured product may not have the desired mechanical properties, or the uncured photocurable organopolysiloxane composition may not have adequate thixotropy. (BET specific surface area of ​​400 m²) 2If the amount exceeds [amount] / g, mixing becomes difficult, and the ability to cure by light may be significantly reduced. Examples of fine silica powder include aerosol silica (dry silica), precipitated silica (wet silica), and colloidal silica, but among these, aerosol silica is particularly preferred.

[0056] Furthermore, examples of hydrophobic agents for the fine silica powder include organochlorosilane, organodichlorosilane, organodisilazane, cyclic organopolysilazane, and linear organopolysiloxane. By treating the fine silica powder with these hydrophobic agents, a hydrophobic silica-based filler can be obtained. Specific hydrophobic groups possessed by the above hydrophobic agents include dimethylsilylene, trimethylsilyl, dimethylvinylsilyl, trifluoropropylsilyl, and polydimethylsiloxy groups, with dimethylsilylene, trimethylsilyl, and polydimethylsiloxy groups being particularly preferred.

[0057] The amount of component (F) is preferably 2 to 50 parts by mass, more preferably 10 to 40 parts by mass, and even more preferably 15 to 30 parts by mass, per 100 parts by mass of component (A). If the amount is 2 parts by mass or more, the composition can be effectively given thixotropy, and if it is 50 parts by mass or less, the decrease in the photocurability of the composition can be suppressed.

[0058] [Other Components] The composition of the present invention may also contain the following other components, to the extent that they do not impair the effects of the present invention. Examples of other components include reaction control agents such as 3-methyl-1-buty-3-ol and ethynylmethyldecylcarbinol to control the reactivity of the platinum catalyst; adhesion aids having adhesion-imparting groups such as carbonyl groups, epoxy groups, and alkoxysilyl groups; antioxidants; light stabilizers; heat-resistant improvers such as metal oxides and metal hydroxides; pigments such as titanium dioxide; dyes; thermally conductive fillers such as alumina; viscosity modifiers such as non-reactive silicone oils that do not have reactive functional groups; conductivity imparters such as metal powders such as silver and gold; thixotropic agents, etc.

[0059] The organopolysiloxane composition of the present invention can be obtained by mixing components (A) to (F) above and other components as needed in any order, and stirring. The apparatus used for stirring and other operations is not particularly limited, but a grinder, a three-roll mill, a ball mill, a planetary mixer, etc., can be used. These apparatuses may also be combined as appropriate.

[0060] From the viewpoint of shape retention and workability during application, the viscosity of the organopolysiloxane composition of the present invention is preferably in the range of 10 to 200 Pa·s, and more preferably in the range of 30 to 150 Pa·s, when measured at 23°C using a rotational viscometer.

[0061] The organopolysiloxane composition of the present invention, at 23°C, with a shear rate of 10s, -1 Shear rate 1s for viscosity V10 -1 The viscosity ratio (V1 / V10) is preferably in the range of 1.0 to 10.0, more preferably in the range of 2.0 to 8.0, and particularly preferably in the range of 3.0 to 6.0. When the V1 / V10 ratio is within the above range, it is easy to ensure discharge performance and it is possible to suppress flow after application.

[0062] [Cured Product] The photocurable organopolysiloxane composition of the present invention can be rapidly cured by irradiation with high-energy rays such as ultraviolet light. In this case, examples of ultraviolet light sources to irradiate the composition of the present invention include UV-LED lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, carbon arc lamps, xenon lamps, etc. The amount of ultraviolet irradiation (cumulative light dose) is preferably 500 to 20,000 mJ / cm² for a sheet formed from the composition of the present invention to a thickness of about 2.0 mm. 2 More preferably, 1,000 to 10,000 mJ / cm² 2 That is, an illuminance of 100 mW / cm². 2 When using ultraviolet light, irradiation for about 10 to 100 seconds is sufficient. The temperature during irradiation is not particularly limited, but 10 to 60°C is preferred, and 20 to 40°C is more preferred.

[0063] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0064] [Examples 1-3, Comparative Examples 1-5] The following components (A) to (F) and other components were mixed in the amounts (parts by mass) shown in Table 1 to prepare photocurable organopolysiloxane compositions S1 to S8.

[0065] (A) Components (A-i) (A-1) Dimethylpolysiloxane with dimethylvinylsiloxy groups sealed at both ends of the molecular chain, with a viscosity of 10 Pa·s at 25°C (vinyl group content: 0.0053 mol / 100g) (A-2) Dimethylpolysiloxane with dimethylvinylsiloxy groups sealed at both ends of the molecular chain, with a viscosity of 5.0 Pa·s at 25°C (vinyl group content: 0.0060 mol / 100g) (A-ii) (A-3) [Me2ViSiO 1 / 2 ] Unit 6 mol%, [Me3SiO 1 / 2 ] Units 40 mol% and [SiO 4 / 2 Organopolysiloxane resin consisting of 54 mol% units (weight-average molecular weight: 6,000, vinyl group content: 0.85 mol / 100g)

[0066] (B) Component (B-1) [MeSiO 3 / 2 ] Unit 50 mol%, and [Me2ViSiO 1 / 2 Organopolysiloxane consisting of 50 mol% units (viscosity at 25°C: 24 mPa·s, vinyl group content: 0.54 mol / 100g, number of vinyl groups per molecule: 12.5)

[0067] (C) Component (C-1) Methylhydrogenpolysiloxane having SiH groups at both ends of the molecular chain and in the side chain (SiH group amount: 0.0125 mol / g) (Kinematic viscosity at 23°C: 44.7 mm) 2 / s)

[0068] (D) Component (D-1) Toluene solution of (methylcyclopentadienyl)trimethylplatinum(IV) complex (platinum content 0.5% by mass)

[0069] (E) Components (E-1) Polyoxyethylene polyoxypropylene monobutyl ether (UNILUVE® C manufactured by NOF Corporation) (E-2) Polyoxypropylene diaryl ether (UNILUVE® DP-2400S manufactured by NOF Corporation)

[0070] (F) Component (F-1) BET with a specific surface area of ​​240 m², surface-treated with dimethyldichlorosilane. 2 Silica (manufactured by Nippon Aerosil Co., Ltd., AEROSIL® R976S)

[0071] (Other ingredients) (Reaction control agent 1) Triallyl isocyanurate (TAIC, manufactured by Shinryo Co., Ltd.) (Reaction control agent 2) Diallyl maleate solution of toluene (concentration 1% by mass) (Thixotropic agent) 3-Glycidoxypropyltrimethoxysilane (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.)

[0072] The organopolysiloxane compositions obtained in Examples 1-3 and Comparative Examples 1-5 were evaluated for their shear viscosity and storage stability by the method described later. The results are shown in Table 1.

[0073] The shear viscosity at 23°C was measured using a thixotropic rotational rheometer HAAKE MARS40 (manufactured by Thermo Fisher Scientific). Shear rate: 10 s -1 and 1s -1 Measurements were taken for 5 minutes. The obtained shear rate was 10 s. -1 Shear rate 1s for viscosity V10 -1 The ratio of viscosity V1, V1 / V10, was defined as thixotropic.

[0074] Storage Stability: Each organopolysiloxane composition was sealed in a light-shielding container and stored for one month and two months in an environment of 21°C to 25°C. The shear rate at 23°C was 10s. -1 The shear viscosity was measured in the same manner as described above, and the storage stability under conditions without UV irradiation was evaluated.

[0075]

[0076] Furthermore, the curability and physical properties of the cured products of the organopolysiloxane compositions obtained in Examples 1-3 and Comparative Examples 1-5 were evaluated under ultraviolet irradiation at 23°C using the method described later. These results are shown in Table 2.

[0077] The curing properties under UV irradiation at 23°C were evaluated using a curing rotary rheometer ARES G2 (manufactured by TA Instruments). A UV-LED irradiation device manufactured by CCS Corporation was used as the light source, and the irradiation dose was 4,000 mJ / cm² of ultraviolet light with a wavelength of 365 nm in air at room temperature (23°C). 2 The material was irradiated in such a manner. The curing properties were evaluated by defining the gelation time as the time when the storage modulus and loss modulus became equal, starting from the point when the UV irradiation ended.

[0078] The cured material's physical composition was poured into a mold, and then irradiated with UV-LED light at a wavelength of 365 nm at a dose of 4,000 mJ / cm² using a UV-LED irradiation device manufactured by CCS Corporation in air at room temperature (23°C). 2 The material was irradiated in such a manner that a 2 mm thick test sheet was prepared. The hardness (durometer A), elongation at break (%), and tensile strength (MPa) of the obtained sheet were measured in accordance with JIS K 6249:2003.

[0079]

[0080] As shown in Tables 1 and 2, the organopolysiloxane compositions of the present invention (Examples 1-3) exhibited good curability, small viscosity changes from the initial stages of production, and excellent storage stability. On the other hand, Comparative Examples 1-5, while exhibiting curability comparable to Examples 1-3, underwent gelation within two months of production or experienced a significant increase in viscosity.

Claims

1. (A) The following (A-i) and / or (A-ii), (A-i) [R 1 2R 2 SiO 1 / 2 units and [R 1 2SiO 2 / 2 units and / or [R 1 R 2 SiO 2 / 2 units (R 1 is independently an unsubstituted or halogen-substituted monovalent hydrocarbon group having no aliphatic unsaturated bond, and R 2 is an alkenyl group.), a linear organopolysiloxane composed of (A-ii) [R 1 2R 2 SiO 1 / 2 units (R 1 is independently an unsubstituted or halogen-substituted monovalent hydrocarbon group having no aliphatic unsaturated bond, and R 2 is an alkenyl group.) and an organopolysiloxane resin having [SiO 4 / 2 units (B) [R 1 2R 2 SiO 1 / 2 units and [R 1 SiO 3 / 2 units (R 1 is independently an unsubstituted or halogen-substituted monovalent hydrocarbon group having no aliphatic unsaturated bond, and R 2 is an alkenyl group.), an organopolysiloxane having no [SiO 4 / 2 units, (C) an organohydrogenpolysiloxane having two or more hydrosilyl groups in one molecule, (D) a photoactive hydrosilylation reaction catalyst, (E) a polyether and / or a polyether derivative, and (F) a photocurable organopolysiloxane composition containing silica having a BET specific surface area of 50 to 400 m 2 / g and a hydrophobic surface-treated surface.

2. The photocurable organopolysiloxane composition according to claim 1, wherein component (D) is a photoactive platinum complex having a β-diketone compound or a cyclic diene compound as a ligand.

3. The photocurable organopolysiloxane composition according to claim 1, wherein component (E) has a linear or branched alkylene group having 2 to 4 carbon atoms in the main chain.

4. A photocurable organopolysiloxane composition according to any one of claims 1 to 3, for use as a 3D printer material.

5. A cured product of a photocurable organopolysiloxane composition according to any one of claims 1 to 3.

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