Radically polymerizable group-containing cyclic organosiloxane, method for producing the same, and curable composition containing the same

Abstract

To provide radically polymerizable group-containing cyclic siloxane which has a low viscosity and gives a cured product being excellent in hardness, impact resistance, and adhesion to a substrate, and having a small curing shrinkage.SOLUTION: A radically polymerizable group-containing cyclic organosiloxane is represented by formula (1).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a radically polymerizable group-containing cyclic organosiloxane, a method for producing the same, and a curable composition containing the same. [Background technology]

[0002] Compounds with a cyclic siloxane main skeleton and polymerizable organic functional groups are used as binders for electronic material encapsulants, lens molding materials, and paint binders for hard coats and other applications due to the excellent heat resistance, weather resistance, and low cure shrinkage of the siloxane skeleton.

[0003] For example, Patent Document 1 proposes a technology for improving the hardness required for a hard coat, flexibility to withstand impacts, and weather resistance against long-term outdoor exposure, by reacting a cyclic siloxane derivative having a hydroxyl group (-OH) with a compound having an isocyanato group (-N=C=O) and a (meth)acryloyl group, thereby introducing a (meth)acryloyl group-containing group as a polymerizable functional group into the cyclic siloxane skeleton via a urethane bond [-O-(C=O)-NH-], and applying the resulting compound to the binder of a photocurable coating composition using a polyfunctional (meth)acrylate.

[0004] However, multifunctional (meth)acrylate compounds containing urethane bonds are prone to aggregation and high viscosity due to intermolecular interactions at the urethane bond sites, and require dilution with organic solvents, posing problems in terms of handling and environmental impact.

[0005] Furthermore, Patent Documents 2 to 4 propose silicone oligomers in which polymerizable functional groups are introduced via Si-O-C bonds. However, these siloxane skeletons all have a random structure because they are composed of condensates of tetrafunctional siloxane units such as tetrachlorosilane and silicate, making it difficult to control the structure of the main chain. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2020-66577 [Patent Document 2] Japanese Patent Application Publication No. 10-245247 [Patent Document 3] Japanese Patent Application Laid-Open No. 2005-258119 [Patent Document 4] Japanese Patent Application Laid-Open No. 2016-209874 Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a radically polymerizable group-containing cyclic siloxane that has low viscosity and gives a cured product that has excellent hardness, impact resistance, and adhesion to substrates and exhibits little cure shrinkage, a method for producing the same, and a curable composition containing the same. [Means for solving the problem]

[0008] As a result of extensive research conducted by the present inventors to achieve the above-mentioned object, they discovered that cyclic organosiloxanes in which a radically polymerizable functional group is introduced into a cyclic siloxane structure via an Si-O-C bond have low viscosity despite a small functional group equivalent, and also give cured products that are excellent in hardness, impact resistance, and adhesion to substrates and exhibit little cure shrinkage, thereby completing the present invention.

[0009] That is, the present invention is 1. A radically polymerizable group-containing cyclic organosiloxane represented by the following formula (1): [ka] (In the formula, R 1 each independently represents a monovalent hydrocarbon group, and R 2 each independently represents a monovalent hydrocarbon group or a hydrogen atom, and R 3represents a hydrogen atom or a methyl group, A represents a divalent hydrocarbon group having 1 to 10 carbon atoms, n is an integer of 2 to 6, m is an integer of 0 to 4, and the sum of n and m is 4 to 6. The arrangement of the siloxane units in the parentheses may be arbitrary. 2. The radical polymerizable group-containing cyclic organosiloxane of 1, wherein A is a divalent saturated hydrocarbon group having 2 to 4 carbon atoms. 3. A method for producing a radically polymerizable group-containing cyclic organosiloxane according to 1, which comprises dehydrogenating a cyclic hydrogensiloxane represented by the following formula (2) with a compound represented by the following formula (3) in the presence of an amine catalyst: [ka] (In the formula, R 1 each independently represents a monovalent hydrocarbon group, p is an integer of 2 to 6, q is an integer of 0 to 4, and the sum of p and q is 4 to 6. The arrangement of the siloxane units in the parentheses may be arbitrary. [ka] (In the formula, R 3 represents a hydrogen atom or a methyl group, and A represents a divalent hydrocarbon group having 1 to 10 carbon atoms. 4. The method for producing a radically polymerizable group-containing cyclic organosiloxane according to 3, wherein the amine catalyst is diethylhydroxylamine. 5. (A)1 radically polymerizable group-containing cyclic organosiloxane, and (B) Polymerization initiator a curable composition comprising: 6. The curable composition according to 5, further comprising, as component (C), a polymerizable unsaturated group-containing compound other than component (A); 7. A cured product of the curable composition of 5 or 6. 8. Articles having a cured product of the curable composition of 5 or 6 to provide. [Effects of the Invention]

[0010] The radically polymerizable group-containing cyclic organosiloxane of the present invention has a structure in which polymerizable unsaturated groups, such as acryloyl groups and methacryloyl groups, are linked to the cyclic siloxane main skeleton via Si-O-C bonds. Therefore, even when the radically polymerizable group equivalent weight is small (the functional group density is high), the viscosity is low, and the cured product obtained from the polymerizable composition containing the radically polymerizable group-containing cyclic organosiloxane of the present invention has excellent hardness, impact resistance, and adhesion to substrates, and exhibits little cure shrinkage. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention will be specifically described below. The radically polymerizable group-containing cyclic organosiloxane according to the present invention is represented by formula (1): The arrangement of the siloxane units in the parentheses may be arbitrary.

[0012] [ka]

[0013] In formula (1), R 1 each independently represents a monovalent hydrocarbon group; R 2 each independently represents a monovalent hydrocarbon group or a hydrogen atom, and R 3 is a hydrogen atom or a methyl group. R 1 and R 2 Specific examples of the monovalent hydrocarbon group may be linear, branched, or cyclic, but preferably have 1 to 20 carbon atoms. Specific examples include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-hexyl, cyclohexyl, n-octyl, 2-ethylhexyl, and n-decyl; alkenyl groups such as vinyl, allyl (2-propenyl), 1-propenyl, isopropenyl, and butenyl; aryl groups such as phenyl, tolyl, xylyl, and naphthyl; and aralkyl groups such as benzyl, phenylethyl, and phenylpropyl.

[0014] Among these, alkyl groups having 1 to 20 carbon atoms and aryl groups having 6 to 12 carbon atoms are preferred, alkyl groups having 1 to 10 carbon atoms are more preferred, alkyl groups having 1 to 5 carbon atoms are even more preferred, and methyl groups, ethyl groups, and n-propyl groups are most preferred from the viewpoint of marketability of the raw materials used.

[0015] In formula (1), A is a divalent hydrocarbon group having 1 to 10 carbon atoms, and the divalent hydrocarbon group may be linear, branched, or cyclic. Specific examples thereof include linear or branched alkylene groups such as methylene, ethylene, trimethylene, propylene, tetramethylene, isobutylene, dimethylethylene, pentamethylene, 2,2-dimethyltrimethylene, hexamethylene, heptamethylene, octamethylene, nonamethylene, and decylene (decamethylene); and arylene groups such as 1,2-phenylene, 1,3-phenylene, 1,4-phenylene, toluenediyl, xylenediyl, and naphthalenediyl.

[0016] Among these, divalent saturated hydrocarbon groups having 2 to 4 carbon atoms are preferred, with ethylene, trimethylene, propylene and tetramethylene groups being more preferred.

[0017] In formula (1), n ​​is an integer of 2 to 6, m is an integer of 0 to 4, and the sum of n and m is 4 to 6. Preferably, n is an integer of 2 to 4, m is an integer of 0 to 2, and the sum of n and m is 4. If n is less than 2, the hardness of the cured product will be insufficient, and if n is more than 6, the structure will have too many polymerizable functional groups, resulting in an excessively high crosslink density of the cured product, which may result in reduced impact resistance.

[0018] The kinematic viscosity of the radically polymerizable group-containing cyclic organosiloxane of the present invention is 1 to 1,000 mm from the viewpoint of handling. 2 / s is preferable, 10 to 100 mm 2 The kinematic viscosity is a value measured at 25°C using, for example, an Ubbelohde viscometer or a Cannon-Fenske viscometer.

[0019] In order to impart sufficient hardness and impact resistance to the resulting cured product, the weight-average molecular weight of the radically polymerizable group-containing cyclic organosiloxane of the present invention is preferably 400 to 4,000. The weight-average molecular weight in the present invention is a value calculated using standard polystyrene standards by gel permeation chromatography (GPC).

[0020] The functional group equivalent of the radically polymerizable group in the radically polymerizable group-containing cyclic organosiloxane of the present invention is preferably 200 to 500 g / mol, in order to provide the resulting cured product with sufficient hardness and impact resistance. If it is 200 g / mol or more, a cured product with excellent hardness can be obtained, and if it is 500 g / mol or less, a cured product with excellent flexibility and impact resistance can be obtained.

[0021] The radically polymerizable group-containing cyclic organosiloxane of the present invention can be obtained, for example, by dehydrogenating a cyclic hydrogen siloxane represented by the following formula (2) with a compound represented by the following formula (3) in the presence of an amine catalyst.

[0022] [ka]

[0023] [ka]

[0024] In each of the above formulas, R 1 , R 3 and A have the same meaning as above, p is an integer of 2 to 6, preferably 2 to 4, q is an integer of 0 to 4, preferably 2 to 4, and the sum of p+q is 4 to 6, preferably 4. In the above formula (2), the arrangement of the siloxane units in the parentheses may be arbitrary.

[0025] Specific examples of the cyclic hydrogen siloxane represented by the above formula (2) include 1,3,5,7-tetramethylcyclotetrasiloxane, 1,3,5,7-tetramethyl-1,3-dipropylcyclotetrasiloxane, and 1,3,5,7-tetramethyl-1,5-dipropylcyclotetrasiloxane.

[0026] Specific examples of the compound represented by the above formula (3) include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, and 4-hydroxybutyl methacrylate.

[0027] The amine catalyst is not particularly limited, and commercially available products can be used, but amine compounds having no NH group are preferred, and among them, diethylhydroxylamine is more preferred from the viewpoints of basicity and availability. Metal complexes such as platinum and palladium complexes can also function as catalysts for this reaction, but are not preferred because they also induce a hydrosilylation reaction between the hydrosilyl group and the olefin moiety of the polymerizable group.

[0028] From the standpoint of reaction efficiency, the amount of the amine catalyst used is preferably 0.001 to 0.1 mol, and more preferably 0.005 to 0.05 mol, per 1 mol of Si—H groups in the cyclic hydrogensiloxane.

[0029] In the dehydrogenation reaction, an organic solvent may be used, if necessary. The organic solvent is not particularly limited as long as it can sufficiently dissolve the raw materials without reacting with them. Examples include non-polar hydrocarbon solvents such as hexane, heptane, and cyclohexane; ether solvents such as tetrahydrofuran, 4-methyltetrahydropyran, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, propylene glycol monomethyl ether monoacetate, and cyclopentyl methyl ether; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, and cyclohexanone; and aromatic solvents such as toluene and xylene. Among these, ether solvents and aromatic solvents are preferred in terms of reactivity and solubility. The organic solvents can be used alone or in combination.

[0030] The reaction time for the dehydrogenation reaction can be appropriately set depending on the progress of the reaction, but is preferably 1 to 10 hours, more preferably 2 to 7 hours. The reaction temperature may be appropriately changed depending on the boiling points of the raw materials and the solvent used, but is preferably in the range of 40 to 100°C.

[0031] The curable composition of the present invention comprises (A) the above-described radically polymerizable group-containing cyclic organosiloxane of the present invention and (B) a polymerization initiator.

[0032] The polymerization initiator of component (B) may be appropriately selected from the viewpoints of compatibility with the curable composition and curability. Specific examples thereof include carbonyl compounds such as benzoin, benzoin monomethyl ether, benzoin isopropyl ether, acetoin, benzil, benzophenone, p-methoxybenzophenone, diethoxyacetophenone, benzil dimethyl ketal, 2,2-diethoxyacetophenone, 1-hydroxycyclohexyl phenyl ketone, methylphenyl glyoxylate, and 2-hydroxy-2-methyl-1-phenylpropan-1-one; tetramethylthiophene; Examples include sulfur compounds such as uram monosulfide and tetramethylthiuram disulfide; phosphoric acid compounds such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide and bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide; and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone-1 and camphorquinone. These may be used alone or in combination of two or more, and can be combined as desired depending on the required coating film performance.

[0033] The content of the polymerization initiator in the composition is preferably 0.1 to 10 parts by mass, and more preferably 1 to 8 parts by mass, per 100 parts by mass of the total of the (meth)acrylate compound and binder precursor, in order to moderate the curing rate of the resulting coating film, improve the scratch resistance and adhesion to the substrate of the cured coating film, and prevent coloration and a decrease in weather resistance.

[0034] The curable composition of the present invention may contain, as necessary, a polymerizable unsaturated group-containing compound other than the component (A) as the component (C). Examples of component (C) include monofunctional (meth)acrylates and polyfunctional (meth)acrylates having a polymerizable unsaturated bond, such as urethane (meth)acrylate, epoxy (meth)acrylate, and polyester (meth)acrylate, and can be selected appropriately depending on the performance required of the coating film.

[0035] Specific examples of monofunctional (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, t-butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, morpholyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, glycidyl (meth)acrylate, and dimethylamino Examples of the acrylate include ethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, tricyclodecane (meth)acrylate, polyethylene glycol mono(meth)acrylate, cyclohexyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, isobornyl (meth)acrylate, allyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenyl (meth)acrylate, and an adduct of phthalic anhydride and 2-hydroxyethyl (meth)acrylate.

[0036] Specific examples of polyfunctional (meth)acrylates include neopentyl glycol di(meth)acrylate, ethylene glycol di(meth)acrylate, polyethylene glycol (number of repeating units (hereinafter referred to as "k") = 2 to 15) di(meth)acrylate, polypropylene glycol (k = 2 to 15) di(meth)acrylate, polybutylene glycol (k = 2 to 15) di(meth)acrylate, 2,2-bis(4-(meth)acryloxyethoxyphenyl)propane, 2,2-bis(4-(meth)acryloxydiethoxyphenyl)propane, trimethylolpropane diacrylate, bis(2-(meth)acryloxyethoxyphenyl)propane, )acryloxyethyl)-hydroxyethyl-isocyanurate, trimethylolpropane tri(meth)acrylate, tris(2-(meth)acryloxyethyl)isocyanurate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, epoxy poly(meth)acrylates such as epoxy di(meth)acrylates obtained by reacting bisphenol A diepoxy with (meth)acrylic acid, 1,Urethane tri(meth)acrylate obtained by reacting 2-hydroxyethyl (meth)acrylate with a trimer of 6-hexamethylene diisocyanate, urethane di(meth)acrylate obtained by reacting isophorone diisocyanate with 2-hydroxypropyl (meth)acrylate, urethane hexa(meth)acrylate obtained by reacting isophorone diisocyanate with pentaerythritol tri(meth)acrylate, urethane di(meth)acrylate obtained by reacting dicyclohexyl diisocyanate with 2-hydroxyethyl (meth)acrylate, dicyclo Examples of suitable poly(meth)acrylates include urethane poly(meth)acrylates such as urethane di(meth)acrylate obtained by reacting a urethane reaction product of hexyl diisocyanate and poly(k=6-15) tetramethylene glycol with 2-hydroxyethyl (meth)acrylate, polyester (meth)acrylates obtained by reacting trimethylolethane with succinic acid and (meth)acrylic acid, and polyester poly(meth)acrylates such as polyester (meth)acrylates obtained by reacting trimethylolpropane with succinic acid, ethylene glycol, and (meth)acrylic acid.

[0037] When component (C) is used, its content is preferably 1 to 100 parts by mass, and more preferably 5 to 90 parts by mass, per 100 parts by mass of the total of components (A) and (C), in order to improve the scratch resistance and adhesion to substrates of a cured product obtained from the composition. The component (C) may be used alone or in combination of two or more.

[0038] The curable composition of the present invention may contain an inorganic filler, if necessary. Examples of inorganic fillers include fine particles of oxides of Si, Ti, Al, Zn, Zr, In, Sn, Sb, etc., and fine particles of composite oxides thereof. These fine particles may also be coated with silica, alumina, etc. Specific examples of metal oxide fine particles include silica, alumina, zirconia, titania, etc., and silica fine particles are preferred. Addition of such metal oxide fine particles can further improve the properties of the cured product, such as abrasion resistance.

[0039] The curable composition of the present invention may contain other additives within the range that does not impair the effects of the present invention. Examples of such additives include ultraviolet absorbers, antifouling agents, water repellents, leveling agents, colorants, pigments, antioxidants, anti-yellowing agents, bluing agents, antifoaming agents, thickeners, anti-settling agents, antistatic agents, surfactants, adhesion promoters, infrared absorbers, light stabilizers, and curing catalysts other than the above-mentioned photopolymerization and thermal polymerization initiators.

[0040] Furthermore, the composition of the present invention is preferably in a solvent-free form that does not substantially contain organic solvents (which are often harmful to the human body and flammable), but a solvent may be added depending on the intended use and workability. Here, "substantially" means that the solvent contained in the composition is 1% by mass or less, particularly 0.1% by mass or less. Specific examples of solvents that can be used include the same organic solvents as those used in producing the above-mentioned (A) radically polymerizable group-containing cyclic organosiloxane of the present invention. The solvent also includes those that are not intentionally added to the curable composition, such as reaction solvents that could not be completely removed by distillation under reduced pressure.

[0041] The curable composition of the present invention can be cured by heating and / or light to obtain a corresponding cured product, the form of which is not particularly limited, and may be a coating film applied to various substrates and cured, or a free-standing molded product or sealed product. Photocuring is the preferred curing method from the viewpoint of productivity. When curing with light, a high-pressure mercury lamp, a metal halide lamp, an LED lamp, or the like is used as a light source to irradiate ultraviolet rays or electron beams of a wavelength appropriate for the polymerization initiator. The atmosphere for irradiation may be air or an inert gas such as nitrogen or argon. When irradiating with ultraviolet rays, for example, 1 to 1000 mJ / cm is used.2 It is preferable to set it to about this level.

[0042] Examples of substrates include, but are not limited to, organic resins such as plastic molded bodies, wood-based products, fibers, ceramics, glass, metals, calcium phosphates such as hydroxyapatite, and composites thereof, and are suitable for use with various plastic materials and calcium phosphates. In particular, the substrate is suitable for use with polycarbonate resins, polystyrene resins, acrylic resins, modified acrylic resins, urethane resins, thiourethane resins, polycondensates of halogenated bisphenol A and ethylene glycol, acrylic urethane resins, halogenated aryl group-containing acrylic resins, sulfur-containing resins, polyalkylene terephthalate resins, polyimide resins, polyamide resins, polycycloolefin resins, polyphenylene sulfide resins, polyphenylene oxide resins, cellulose resins, amorphous polyolefin resins, and composite resins thereof.

[0043] Furthermore, the surface of these substrates may be treated, specifically, chemically treated, corona discharge treated, flame treated, plasma treated, or treated with an acid or alkaline solution, or a laminate whose surface layer is coated with a resin of a different type from that of the substrate itself may be used. Specific examples of the laminate include a laminate produced by coextrusion or lamination in which an acrylic resin layer or a urethane resin layer is present on the surface layer of a polycarbonate resin substrate, and a laminate in which an acrylic resin layer is present on the surface layer of a polyester resin substrate. The curable composition may be applied directly to the surface of the substrate, or may be applied via a primer layer, an ultraviolet absorbing layer, a printing layer, a recording layer, a heat ray shielding layer, an adhesive layer, an inorganic vapor deposition film layer, or the like, as needed.

[0044] The coating method can be appropriately selected from known coating methods such as a spin coater, comma coater, lip coater, roll coater, die coater, knife coater, blade coater, rod coater, kiss coater, gravure coater, screen coating, dip coating, and cast coating.

[0045] Furthermore, if necessary, other coating layers such as an adhesive layer, an ultraviolet absorbing layer, a printing layer, a recording layer, a heat ray shielding layer, a pressure-sensitive adhesive layer, an inorganic vapor deposition film layer, a water- and oil-repellent layer, or a hydrophilic antifouling layer may be formed on the surface of the cured coating film of the curable composition of the present invention.

[0046] Methods for producing a self-supporting cured molded product using the curable composition of the present invention include, but are not limited to, a method using a mold, as well as a film-forming method using a casting method in which the composition is coated on a film previously provided with a release layer and cured.

[0047] The material of the molding die is not particularly limited as long as it ensures releasability from the cured product obtained after curing, and may be, for example, metal, glass, plastic, silicone, or a Teflon (registered trademark)-coated die. However, it is preferable to use a Teflon (registered trademark)-coated die, as it has excellent releasability and can prevent breakage when removing the cured product.

[0048] The cured products obtained from the curable composition of the present invention can be used in scratch-resistant hard coatings for plastic substrates, optical lens moldings, flexible display materials for electronic materials, optical encapsulants for LED devices, and denture molding materials and dental filling agents for dental and medical use. [Example]

[0049] The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. In the following examples, unless otherwise specified, "parts" and "%" mean "parts by mass" and "% by mass," respectively. The kinematic viscosity was measured at 25°C using a Cannon-Fenske viscometer. The following instruments were used in the examples:

[0050] (1) GPC measurement conditions Apparatus: Tosoh Corporation HLC-8320GPC Developing solvent: tetrahydrofuran (THF) Flow rate: 0.6mL / min Detector: Refractive index detector (RI) Column: TSK Guardcolumn SuperH-H TSKgel SuperHM-N(6.0mmI.D.×15cm×1) TSKgel SuperH2500(6.0mmI.D.×15cm×1) (All manufactured by Tosoh Corporation) Column temperature: 40℃ Sample injection volume: 50 μL (2.0% by mass THF solution) Standard: Monodisperse polystyrene (2) Proton nuclear magnetic resonance ( 1 H-NMR spectrum measurement conditions Equipment: BURKER AVANCE III400 Solvent: CDCl3 Internal standard: tetramethylsilane (TMS)

[0051] [1] Synthesis of cyclic organosiloxanes containing radically polymerizable groups [Example 1] 476 g (4.1 mol) of 2-hydroxyethyl acrylate and 400 g of toluene were placed in a 1 L three-neck flask equipped with a stirrer, condenser, dropping funnel, and thermometer, and heated to 80°C using an oil bath. 1.07 g (0.012 mol) of diethylhydroxylamine was added to the flask, and 240 g (1 mol) of 1,3,5,7-tetramethylcyclotetrasiloxane was added dropwise while stirring, keeping the internal temperature between 80 and 90°C. After the dropwise addition, the mixture was stirred at 80°C for 4 hours, and then heated to 80°C for 4 hours. 1 The decrease in the peaks derived from the reaction raw materials and the generation of peaks derived from the target product were confirmed in the H-NMR spectrum. The mixture was then cooled to 25°C, and the unreacted 2-hydroxyethyl acrylate and amine catalyst were removed by washing with water. The solvent, toluene, was removed by vacuum distillation to obtain a pale yellow, transparent liquid (A-1). The kinematic viscosity of this product at 25°C was 39 mmH. 2 The copolymer had an acrylic equivalent of 174 g / mol and a weight-average molecular weight of 855. The above (A-1) is1 As a result of analysis by 1 H-NMR, GPC, etc., it was found to be a compound represented by the following formula (4).

[0052] [ka]

[0053] [Example 2] A pale yellow, transparent liquid (A-2) was obtained by the same procedure as in Example 1, except that the 1,3,5,7-tetramethylcyclotetrasiloxane in Example 1 was replaced with a 1:1 (molar) mixture of the same molar amounts of 1,3,5,7-tetramethyl-1,3-dipropylcyclotetrasiloxane and 1,3,5,7-tetramethyl-1,5-dipropylcyclotetrasiloxane. The kinematic viscosity of this liquid at 25°C was 13 mmHg. 2 The acrylic equivalent was 276 g / mol and the weight-average molecular weight was 731. The above (A-2) is 1 Analysis by H-NMR, GPC, etc. revealed that the product was a mixture of compounds represented by the following formulas (5) and (6).

[0054] [ka]

[0055] [Example 3] The same procedure as in Example 1 was carried out, except that 2-hydroxyethyl acrylate was replaced with the same molar amount of 4-hydroxybutyl acrylate, to obtain a pale yellow, transparent liquid (A-3). The kinematic viscosity of this liquid at 25°C was 42 mmHg. 2 The acrylic equivalent was 202 g / mol, and the weight-average molecular weight was 1010. The above (A-3) is 1 As a result of analysis by 1 H-NMR, GPC, etc., it was found to be a compound represented by the following formula (7).

[0056] [ka]

[0057] [Example 4] The same procedure as in Example 2 was carried out except that 2-hydroxyethyl acrylate was replaced with the same molar amount of 4-hydroxybutyl acrylate, to obtain a pale yellow transparent liquid (A-4). The kinematic viscosity of this liquid at 25°C was 16 mmHg. 2 The copolymer had an acrylic equivalent of 306 g / mol and a weight-average molecular weight of 755. The above (A-4) is 1 Analysis by H-NMR, GPC, etc. revealed that the product was a mixture of compounds represented by the following formulas (8) and (9).

[0058] [ka]

[0059] [Example 5] The same procedure as in Example 1 was carried out, except that the 2-hydroxyethyl acrylate in Example 1 was replaced with the same molar amount of 2-hydroxypropyl methacrylate, to obtain a pale yellow, transparent liquid (A-5). The kinematic viscosity of this liquid at 25°C was 65 mm 2 The copolymer had a methacrylic group equivalent of 205 g / mol and a weight-average molecular weight of 986. The above (A-5) is 1 As a result of analysis by 1 H-NMR, GPC, etc., it was found to be a compound represented by the following formula (10).

[0060] [ka]

[0061] [Example 6] The same procedure as in Example 2 was carried out, except that the 2-hydroxyethyl acrylate in Example 2 was replaced with the same molar amount of 2-hydroxypropyl methacrylate, to obtain a pale yellow, transparent liquid (A-6). The kinematic viscosity of this liquid at 25°C was 16 mmHg. 2 The copolymer had a methacrylic group equivalent of 300 g / mol and a weight-average molecular weight of 731. The above (A-6) is 1 Analysis by H-NMR, GPC, etc. revealed that the product was a mixture of compounds represented by the following formulas (11) and (12).

[0062] [ka]

[0063] [2] Preparation of curable composition [Examples 7 to 13, Comparative Examples 1 to 3] The components were mixed in the compounding ratios (parts by mass) shown in Table 1 to prepare curable compositions.

[0064] [Table 1]

[0065] The abbreviations in Table 1 are as follows: PETA: Pentaerythritol tetraacrylate DPHA: Dipentaerythritol hexaacrylate HDDA: hexanediol diacrylate Photopolymerization initiator: α-hydroxyacetophenone (IGB Resin BV, Omnirad 1173)

[0066] The curable compositions in Table 1 were applied to the surfaces of various substrates, such as a polycarbonate (PC) NF-2000 sheet (4 mm thick x 15 cm long x 10 cm wide) manufactured by Mitsubishi Engineering Plastics Corporation, a polyethylene terephthalate (PET) film Cosmoshine A4160 (50 microns thick) manufactured by Toyobo Co., Ltd., and a polished steel plate, using a bar coater No. 14. The applied compositions were then air-dried for 15 minutes, heated at 80°C for 1 minute, and then irradiated with 600 mJ / cm using a high-pressure mercury lamp. 2 The coating film was cured by irradiation with light at an irradiation dose of 10 ...

[0067] The coating films obtained in the above Examples and Comparative Examples were evaluated as follows, and the results are shown in Table 2. (1) Coating appearance (PC, polished steel plate, PET) The coating film was visually inspected to determine whether or not there was any abnormality. ○: No abnormalities ×: Foreign matter, unevenness, whitening abnormalities present (2) Early Haze (PC) The haze of the coated sheet was measured using a haze meter NDH5000SP manufactured by Nippon Denshoku Industries Co., Ltd., and the measured value was taken as the initial haze. (3) Scratch resistance (PC) In accordance with ASTM 1044, a Taber abrasion tester was fitted with an abrasion wheel CS-10F, and the haze value was measured after 100 revolutions under a load of 500 g. The difference in haze value before and after the test was taken as the scratch resistance. (4) Initial adhesion (PC, polished steel plate) In accordance with JIS K5600-5-6:1999, 25 grids were made in the coating film using a razor blade, with six cuts made vertically and six cuts made horizontally at 2 mm intervals. Cellotape (registered trademark, manufactured by Nichiban Co., Ltd.) was then firmly adhered to the grid and the grid was then rapidly peeled off at a 90° angle towards the user. The number of grids (X) that remained without the coating film peeling off was expressed as X / 25. (5) Boiling adhesion (PC, polished steel plate) The evaluation sample was immersed in boiling water for 2 hours, and the adhesion after that was evaluated in the same manner as the initial adhesion. (6) Pencil hardness (PC) Measurement was carried out by applying a load of 750 g in accordance with the pencil scratch test described in JIS K5600-5-4:1999, and the results are shown. (7) Impact resistance (polished steel plate) The impact resistance was measured using a DuPont impact tester in accordance with the weight drop test described in JIS K5600-5-3:1999, and the results are shown below. (8) Cure shrinkage (PET) The test piece was cut to a size of 10 cm x 10 cm, and the center point of the film was fixed to a horizontal plane. The average distance from the horizontal plane to the square of the film that curled due to shrinkage was measured, and the results are shown.

[0068] [Table 2]

[0069] As shown in Table 2, the coating films obtained by curing the curable compositions of Examples 7 to 13 containing the radically polymerizable group-containing cyclic organosiloxane of the present invention have transparency, adhesion, hardness, and impact resistance, and exhibit little cure shrinkage. On the other hand, in Comparative Example 1 using PETA and Comparative Example 2 using DPHA, the adhesion was insufficient, and therefore the scratch resistance also tended to deteriorate, the impact resistance was low, and the cure shrinkage was very large. In Comparative Example 3, in which HDDA was used, the adhesion and cure shrinkage were good, but the hardness was low and, furthermore, the polycarbonate substrate was corroded, resulting in a deterioration in transparency.

Claims

1. A radically polymerizable group-containing cyclic organosiloxane represented by the following formula (1): 【Chemistry 1】 (In the formula, R 1 each independently represents a monovalent hydrocarbon group, R 2 each independently represents a monovalent hydrocarbon group or a hydrogen atom; R 3 represents a hydrogen atom or a methyl group, A represents a divalent hydrocarbon group having 1 to 10 carbon atoms, n is an integer of 2 to 6, m is an integer of 0 to 4, and the sum of n and m is 4 to 6. The arrangement of the siloxane units in the parentheses may be arbitrary.

2. 2. The radically polymerizable group-containing cyclic organosiloxane according to claim 1, wherein A is a divalent saturated hydrocarbon group having 2 to 4 carbon atoms.

3. 2. The method for producing the radical-polymerizable group-containing cyclic organosiloxane according to claim 1, wherein a cyclic hydrogensiloxane represented by the following formula (2) and a compound represented by the following formula (3) are subjected to a dehydrogenation reaction in the presence of an amine catalyst: 【Chemistry 2】 (In the formula, R 1 each independently represents a monovalent hydrocarbon group, p is an integer of 2 to 6, q is an integer of 0 to 4, and the sum of p and q is 4 to 6. The arrangement of the siloxane units in the parentheses may be arbitrary. 【Transformation 3】 (In the formula, R 3 represents a hydrogen atom or a methyl group, and A represents a divalent hydrocarbon group having 1 to 10 carbon atoms.

4. 4. The method for producing a radically polymerizable group-containing cyclic organosiloxane according to claim 3, wherein the amine catalyst is diethylhydroxylamine.

5. (A) the radically polymerizable group-containing cyclic organosiloxane according to claim 1, and (B) Polymerization initiator A curable composition comprising:

6. The curable composition according to claim 5, further comprising a polymerizable unsaturated group-containing compound other than the component (A) as the component (C).

7. A cured product of the curable composition according to claim 5 or 6.

8. An article comprising a cured product of the curable composition according to claim 5 or 6.

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