Thermosetting composition for dumping materials

Abstract

To provide a thermosetting composition for a damping material which is excellent in thermosetting properties and storage stability and is small in temperature dependence of elastic modulus.SOLUTION: The present invention relates to the thermosetting composition for a damping material which contains a binder (A) and a resin filler (B). The binder (A) contains a binder (A-1) having a weight average molecular weight of 250-1,000 and has a viscosity at 25°C of 20-2,000 mPa s. A value obtained by dividing the viscosity of the binder (A) by the weight average molecular weight of the binder (A) is 2 or less. The resin filler (B) has a glass transition temperature (Tg) of 85-115°C and a weight average molecular weight of 50,000-4,000,000 and is not a core-shell type resin filler.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a thermosetting composition for a dump material. [Background technology]

[0002] In precision optical devices such as optical lenses, optical pickups, light detection sensors, and displays for personal computers, etc., when fixing components of each device, damping materials (vibration absorbing materials) are used in areas that are subject to large deformation or vibration to prevent parts from falling off (e.g., Patent Document 1). Photocurable silicone compositions that give flexible cured products are used as such damping materials (e.g., Patent Documents 2 and 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-310916 A [Patent Document 2] JP 2001-261765 A [Patent Document 3] International Publication No. 2011 / 136170 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the ultraviolet curing method could not be applied to the part that could not be irradiated with light. Therefore, there was a demand for a new composition for a dumping material that has excellent thermosetting properties and excellent storage stability. In addition, in order to make a dumping material that can be used in a wide temperature range, there was a demand for a dumping material that has a small temperature dependency of the elastic modulus, which is an index of the dumping characteristics.

[0005] An object of the present invention is to provide a thermosetting composition for a dump material which is excellent in thermosetting property and storage stability and has a small temperature dependency of elastic modulus. [Means for solving the problem]

[0006] The present invention relates to the following: [1] A thermosetting composition for a dump material, comprising a binder (A) and a resin filler (B), wherein the binder (A) comprises a binder (A-1) having a weight-average molecular weight of 250 to 1,000, the binder (A) has a viscosity of 20 to 2,000 mPa·s at 25°C, wherein the value obtained by dividing the viscosity of the binder (A) by the weight-average molecular weight of the binder (A) is 2 or less, the resin filler (B) has a glass transition temperature (Tg) of 85°C to 115°C, and the resin filler (B) has a weight-average molecular weight of 50,000 to 4,000,000, but the resin filler (B) is not a core-shell type resin filler. [2] The thermosetting composition for dump material according to [1], wherein the resin filler (B) is a (meth)acrylic resin filler. [3] The thermosetting composition for dump material according to [1] or [2], wherein the binder (A) comprises one or more selected from the group consisting of acrylic resin-based binders, epoxy resin-based binders, silicone resin-based binders and plasticizer-based binders. [4] The viscosity of the binder (A) at 25°C is 20 mPa· s The thermosetting composition for a dump material according to any one of [1] to [3], having a viscosity of 700 mPa·s or more and less than 700 mPa·s. [5] The thermosetting composition for dumping materials according to any one of [1] to [4], further comprising one or more selected from the group consisting of fillers and antioxidants. Effect of the Invention

[0007] According to the present invention, it is possible to provide a thermosetting composition for a dump material which is excellent in thermosetting property and storage stability and has a small temperature dependency of elastic modulus. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] [Definition] In this specification, the definitions of each term are as follows. "Excellent thermosetting properties" means that a cured product is obtained after heating at 80°C for 1 hour. "Excellent storage stability" means that the rate of change in viscosity of the composition after storage at 25°C for 24 hours is 10% or less. "(Meth)acrylic" means at least one of acrylic and methacrylic, and "(meth)acryloyl group" means at least one of acryloyl group and methacryloyl group. The term "hardening" refers to at least one of gelation and solidification. The "weight average molecular weight" is a value calculated in terms of polystyrene measured by gel permeation chromatography (GPC). "Viscosity" is a value measured at 25°C using a cone-plate type viscometer. "The viscosity of the binder (A) at 25° C." refers to the viscosity of all the binder components contained in the composition. The "weight average molecular weight of binder (A)" refers to the weight average molecular weight of all the binder components contained in the composition. When multiple binders (A) are present, it means the weighted average of the molecular weights of the respective components. For example, when the binder (A) is a combination of three components, component A1, component A2, and component A3, the "molecular weight of binder (A) = (molecular weight of component A1 x content of component A1 + molecular weight of component A2 x content of component A2 + molecular weight of component A3 x content of component A3) / (content of component A1 + content of component A2 + content of component A2)". In relation to a numerical range, the use of "to" means that both ends of the range are included. For example, "250 to 1,000" means "250 or more and 1,000 or less." Additionally, "or less" means "the same as or less than," and "or more" means "the same as or greater than."

[0009] [Thermosetting composition for dumping materials] The thermosetting composition for a dump material comprises a binder (A) and a resin filler (B). The binder (A) comprises a binder (A-1) having a weight average molecular weight of 250 to 1,000. The binder (A) has a viscosity of 20 to 2,000 mPa·s at 25°C, where the value obtained by dividing the viscosity of the binder (A) by the weight average molecular weight of the binder (A) is 2 or less. The resin filler (B) has a glass transition temperature (Tg) of 85°C to 115°C and a weight average molecular weight of 50,000 to 4,000,000, but the resin filler (B) is not a core-shell type resin filler.

[0010] The thermosetting composition for dump materials is cured by swelling of the resin filler (B) in the binder (A) and thickening. The thermosetting composition for dump materials is cured by heating the thermosetting composition, causing the resin filler to swell with the binder, changing from a filler state into polymer chains, and the polymer chains become entangled.

[0011] The present inventors have also found that the temperature dependency of the elastic modulus (particularly the temperature dependency of the elastic modulus at low temperatures) is reduced by setting the value obtained by dividing the viscosity of the binder (A) of the thermosetting composition for dump material by the weight average molecular weight of the binder (A) to 2 or less. Here, since the elastic modulus having a large temperature dependency tends to change significantly especially at low temperatures (e.g., -20°C to 25°C), it can be said that when the temperature dependency of the elastic modulus at low temperatures is reduced, the temperature dependency of the elastic modulus is reduced in a wide temperature range (e.g., -40 to 90°C, particularly -20°C to 80°C).

[0012] In addition to the elastic modulus, the thermosetting composition for dump materials has a small temperature dependency of tan δ, which is an index of damping characteristics. Since the thermosetting composition for dump materials has a small temperature dependency of the elastic modulus over a wide temperature range, when the thermosetting composition for dump materials is used as a damping material (vibration absorbing material) for camera actuators (VCM, OIS), optical pickups, etc., it can exhibit the performance of the damping material over a wide temperature range.

[0013] (Binder (A)) The binder (A) is a component capable of swelling the resin filler (B) when heated. The binder (A) contains a binder (A-1) having a weight average molecular weight of 250 to 1,000, and the binder (A) has a viscosity of 20 to 2,000 mPa s at 25°C, where the value obtained by dividing the viscosity of the binder (A) by the weight average molecular weight of the binder (A) is 2 or less.

[0014] <Viscosity of binder (A)> The viscosity of the binder (A) at 25°C is 20 to 2,000 mPa·s. If the viscosity of the binder (A) at 25°C exceeds 2,000 mPa·s, the temperature dependency of the elastic modulus does not become small. If the viscosity of the binder (A) at 25°C is less than 20 mPa·s, the binder (A) dissolves the resin filler (B), resulting in poor storage stability. The viscosity of the binder (A) should be less than 20 mPa·s. s It may be greater than or equal to 700 mPa·s and less than 700 mPa·s.

[0015] <Binder (A-1)> The binder (A-1) has a weight average molecular weight of 250 to 1,000. When the binder (A) contains only components having a weight average molecular weight of less than 250, the storage stability is poor. When the binder (A) contains only components having a weight average molecular weight of more than 1,000, the thermosetting property is poor. From the viewpoint of thermosetting property, the weight average molecular weight of the binder (A-1) is preferably 350 to 1,000, and particularly preferably 450 to 750.

[0016] <Viscosity of binder (A-1)> The viscosity of the binder (A-1) at 25°C is not particularly limited as long as it is within a range in which the viscosity of the binder (A) at 25°C is 20 to 2,000 mPa s and the value obtained by dividing the viscosity of the binder (A) by the weight average molecular weight of the binder (A) is 2 or less. Thus, examples of the binder (A-1) include the following binder (A-1') and binder (A-1"). The weight average molecular weights of the binder (A-1') and binder (A-1") are 250 to 1,000, and the preferred values ​​are as described above for the binder (A-1).

[0017] <Binder (A-1')> The binder (A-1') has a viscosity at 25°C of 20 mPa·s or more and 2000 mPa·s or less, and the value obtained by dividing the viscosity of the binder (A-1') by the weight average molecular weight of the binder (A-1') is not more than 2. The viscosity of the binder (A-1') at 25°C is preferably 20 mPa·s or more and less than 350 mPa·s.

[0018] <Binder (A-1")> The binder (A-1") is a binder (A-1"-1) having a viscosity at 25°C of 20 mPa·s or more and 2000 mPa·s or less, and the value obtained by dividing the viscosity of the binder (A-1"-1) by the weight average molecular weight of the binder (A-1"-1) exceeds 2; the binder (A-1"-2) has a viscosity at 25°C of less than 20 mPa·s; or the binder (A-1"-3) has a viscosity at 25°C of more than 2,000 mPa·s. When the binder (A-1") is a binder (A-1"-3), the viscosity of the binder (A-1"-3) at 25°C is preferably 100,000 mPa·s or less, and particularly preferably 50,000 mPa·s or less.

[0019] <Binders other than (A-1)> The binder (A) may contain a binder other than the binder (A-1) as an additional binder for the purpose of adjusting the viscosity or weight average molecular weight of the binder (A), etc. Examples of the additional binder include a binder (A-2) having a weight average molecular weight of less than 250 and a binder (A-3) having a weight average molecular weight of more than 1,000.

[0020] <Binder (A-2)> From the viewpoints of thermosetting property and storage stability, the weight average molecular weight of the binder (A-2) is preferably 100 or more and less than 250. The viscosity of the binder (A-2) at 25°C is not particularly limited as long as it is within the range, but is preferably 1 mPa·s or more and 100 mPa·s or less, and particularly preferably 5 mPa·s or more and 50 mPa·s or less.

[0021] <Binder (A-3)> From the viewpoints of thermosetting property and storage stability, the weight average molecular weight of the binder (A-3) is preferably more than 1,000 and not more than 50,000, and particularly preferably 1,500 to 10,000. The viscosity of the binder (A-3) at 25°C is not particularly limited as long as the viscosity of the binder (A) at 25°C and the relationship between the viscosity and the weight average molecular weight of the binder (A) are within the above-mentioned ranges, but is preferably from 400 mPa·s to 100,000 mPa·s, and particularly preferably from 500 mPa·s to 50,000 mPa·s.

[0022] <Type of binder (A)> The type of binder (A) is not particularly limited as long as it satisfies the weight average molecular weight of the binder (A-1), the viscosity of the binder (A) at 25°C, and the relationship between the viscosity of the binder (A) and the weight average molecular weight of the binder (A). Examples of such binder (A) include binders having reactive functional groups such as (meth)acrylic resin binders and epoxy resin binders, and binders not having reactive functional groups such as silicone resin binders and plasticizer binders. Here, the reactive functional group is a group that causes a curing reaction by heating, and examples thereof include (meth)acryloyl groups and epoxy groups.

[0023] <(Meth)acrylic resin binder> The (meth)acrylic resin binder is not particularly limited as long as it is a resin having one or more (meth)acryloyl groups in the molecule. Examples of the (meth)acrylic resin include (meth)acrylate oligomers and (meth)acrylate monomers. Examples of the (meth)acrylate oligomers include urethane (meth)acrylate oligomers and epoxy (meth)acrylate oligomers. Examples of the (meth)acrylate monomers include (meth)acrylate monomers having a ring structure, (meth)acrylate monomers containing a carboxyl group, polyfunctional (meth)acrylate monomers, and other (meth)acrylate monomers. Each of these may be used alone or in combination of two or more.

[0024] ·Urethane (meth)acrylate oligomer The urethane (meth)acrylate oligomer may be an aliphatic, polyether, polycarbonate, polyester, or combination thereof. These may be used alone or in combination of two or more. Among these, the aliphatic type is preferred.

[0025] The urethane (meth)acrylate oligomer can be produced, for example, by reacting an organic diisocyanate with a resin having a hydroxyl group, and then further reacting the resulting resin with a mono- to penta-functional (meth)acrylate having a hydroxyl group, as described in JP 2008-260898 A.

[0026] Examples of the organic diisocyanate include aromatic, aliphatic, and alicyclic diisocyanates, and specific examples thereof include aromatic diisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, modified diphenylmethane diisocyanate, xylylene diisocyanate, and tetramethylxylylene diisocyanate, aliphatic diisocyanates such as hexamethylene diisocyanate and trimethylhexamethylene diisocyanate, and alicyclic diisocyanates such as hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, norbornene diisocyanate, and 1,3-bis(isocyanatomethyl)cyclohexane. Among these, alicyclic diisocyanates are preferred.

[0027] Examples of the resin having hydroxyl groups include polyalkylenes having hydroxyl groups at both ends, hydrogenated polyalkylenes having hydroxyl groups at both ends, polyols having hydroxyl groups at both ends, polycarbonates having hydroxyl groups at both ends, and polyesters having hydroxyl groups at both ends. Polyalkylenes having hydrogenated hydroxyl groups at both ends are preferred, and polybutadiene having hydrogenated hydroxyl groups at both ends and polyisoprene having hydrogenated hydroxyl groups at both ends are more preferred.

[0028] Examples of the mono- to penta-functional (meth)acrylate having a hydroxyl group include hydroxyalkylene (meth)acrylate, trimethylolpropane diacrylate, pentaerythritol triacrylate, dipentaerythritol pentaacrylate, and alkyl oxide modified products thereof.

[0029] Commercially available urethane (meth)acrylate oligomers include EBECRYL4858 (manufactured by Daicel-Allnex Corporation), UN-2301 (manufactured by Negami Chemical Industries, Ltd.), EBECRYL4859 (manufactured by Daicel-Allnex Corporation), EBECRYL4738 (manufactured by Daicel-Allnex Corporation), and EBECRYL8402 (manufactured by Daicel-Allnex Corporation).

[0030] Epoxy (meth)acrylate oligomer The epoxy (meth)acrylate oligomer is an oligomer in which all epoxy groups in an epoxy resin are reacted with (meth)acrylic acid. The epoxy (meth)acrylate oligomer may include an oligomer in which some epoxy groups in an epoxy resin are reacted with (meth)acrylic acid, that is, an oligomer having an epoxy group and a (meth)acryloyl group in the resin. Here, examples of the epoxy resin include aromatic epoxy resins, aliphatic epoxy resins, alicyclic epoxy resins, and other epoxy resins. The epoxy (meth)acrylate oligomer is preferably an epoxy (meth)acrylate oligomer of an aromatic epoxy resin. The epoxy (meth)acrylate oligomer may be one type or a combination of two or more types.

[0031] Commercially available epoxy (meth)acrylate oligomers include EB3700 (manufactured by Daicel-Allnex) and EB3708 (manufactured by Daicel-Allnex).

[0032] Methacrylate monomers with ring structures The methacrylate monomer having a ring structure is preferably at least one selected from the group consisting of alicyclic methacrylate monomers and aromatic methacrylate monomers.

[0033] Examples of the alicyclic methacrylate monomer include dicyclopentenyloxyethyl methacrylate, norbornene methacrylate, dicyclopentanyl methacrylate, isobornyl methacrylate, tetrahydrofurfuryl methacrylate, and cyclohexyl methacrylate.

[0034] Examples of aromatic methacrylate monomers include benzyl methacrylate, phenoxyethyl methacrylate, ethoxylated o-phenylphenol methacrylate, phenoxybenzyl methacrylate, naphthalene methacrylate, ethoxylated bisphenol A dimethacrylate, modified bisphenol A dimethacrylate (bisphenol A diglycidyl ether methacrylic acid adduct, bisphenol A alkylene oxide adduct diglycidyl ether methacrylic acid adduct, 9,9-bis[4-(2-methacryloyloxyethoxy)phenyl]fluorene), and the like.

[0035] (Meth)acrylate monomers containing a carboxyl group Examples of the (meth)acrylate monomer containing a carboxyl group include aliphatic, aromatic and alicyclic (meth)acrylate monomers containing a carboxyl group. Specific examples of (meth)acrylate monomers containing a carboxyl group include (meth)acrylic acid, 2-(meth)acryloyloxyethyl succinic acid, 2-(meth)acryloyloxypropyl succinic acid, 2-(meth)acryloyloxyethyl phthalic acid, 2-(meth)acryloyloxypropyl phthalic acid, 2-(meth)acryloyloxyethyl hexahydrophthalic acid, and 2-(meth)acryloyloxypropyl hexahydrophthalic acid.

[0036] Polyfunctional (meth)acrylate monomers Examples of the polyfunctional (meth)acrylate monomer include esters of aliphatic polyhydric alcohols and (meth)acrylic acid, and esters of alkylene oxide adducts of aliphatic polyhydric alcohols and (meth)acrylic acid. Specific examples of polyfunctional (meth)acrylate monomers include ethoxylated 1,6-hexanediol di(meth)acrylate, 1,6-hexanediol acrylic acid polymer ester, polyester di(meth)acrylate, polyethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, epichlorohydrin-modified glycerol tri(meth)acrylate, ethoxylated glycerol tri(meth)acrylate, PO (propylene oxide)-modified glycerol tri(meth)acrylate, ethoxylated trimethylolpropane triacrylate, and alkoxylated pentaerythritol tetraacrylate.

[0037] Further (meth)acrylate monomers Further (meth)acrylate monomers include alkyl (meth)acrylates such as tert-butyl (meth)acrylate, isooctyl (meth)acrylate, isomyristyl (meth)acrylate, and lauryl (meth)acrylate; and (meth)acrylates having a hydroxyl group such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and diethylene glycol monoethyl ether (meth)acrylate. Other examples of (meth)acrylic resins include those described in JP 2019-129279 A.

[0038] <Epoxy resin binder> The epoxy resin binder is not particularly limited as long as it is a resin having one or more epoxy groups in the molecule (excluding resins having one or more (meth)acryloyl groups in the molecule). One or more epoxy resins selected from the group consisting of aromatic epoxy resins, alicyclic epoxy resins, and aliphatic epoxy resins can be used.

[0039] Examples of aromatic epoxy resins include bisphenol A type epoxy resins (e.g., Epicron 850, Epicron EXA-850CRP, Epicron 860, and Epicron EXA-8067 (Epicron EXA-8067 is a high molecular weight type) manufactured by DIC Corporation), bisphenol F type epoxy resins (e.g., Epicron EXA-830LVP and Epicron 830-S manufactured by DIC Corporation), biphenyl type epoxy resins, naphthalene type epoxy resins, phenol novolac type epoxy resins (e.g., Epicron N-730A manufactured by DIC Corporation), cresol novolac type epoxy resins, and polybutadiene type epoxy resins.

[0040] Examples of the alicyclic epoxy resin include vinylcyclohexene monoxide, 1,2-epoxy-4-vinylcyclohexane (e.g., CEL2000 manufactured by Daicel Corporation), 1,2:8,9 diepoxy limonene (e.g., CEL3000 manufactured by Daicel Corporation), 3,4-epoxycyclohexenylmethyl-3',4'-epoxycyclohexene carboxylate (e.g., CEL2021P manufactured by Daicel Corporation), 1,2-epoxy-4-(2-oxiranyl)cyclohexane adduct of 2,2-bis(hydroxymethyl)-1-butanol (e.g., EHPE3150 manufactured by Daicel Corporation), 3,4-epoxycyclohexenylmethyl-3',4'-epoxycyclohexene carboxylate, hydrogenated bisphenol A type epoxy resin, hydrogenated bisphenol F type epoxy resin, and hydrogenated biphenyl type alicyclic epoxy resin.

[0041] Examples of aliphatic epoxy resins include ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,4-butanediol diglycidyl ether (e.g., SR-14BJ manufactured by Sakamoto Yakuhin Kogyo Co., Ltd.), 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, trimethylolpropane diglycidyl ether, polyethylene glycol diglycidyl ether, polyisoprene-type epoxy resins, and silicon-containing epoxy compounds such as 3-glycidoxypropyltrimethoxysilane.

[0042] <Plasticizer-based binder> The plasticizer-based binder is a component that does not harden by itself when heated. When the thermosetting composition for dump materials contains a plasticizer-based binder, a soft hardened product with a small storage modulus can be obtained. Examples of such plasticizer-based binders include plasticizers having a polyethylene glycol (PEG) structure, an ester structure, etc., such as xylene resin-based plasticizers, acrylic polymer-based plasticizers, phthalate ester-based plasticizers, polyvalent carboxylic acid alkyl ester-based plasticizers, adipate ester-based plasticizers, sebacic acid ester-based plasticizers, polybutadiene-based plasticizers, polyisoprene-based plasticizers, polybutene-based plasticizers, terpene-based plasticizers, rosin ester-based resins, and other plasticizers.

[0043] The xylene resin plasticizer is an aromatic oligomer based on m-xylene, and examples of commercially available products include Nikanol LL and Nikanol L (manufactured by Fudow Co., Ltd.). The acrylic polymer plasticizer is a prepolymerized acrylic polymer (which may or may not contain a reactive group), and examples of commercially available products include UP1061 and UP1010 (manufactured by Toagosei Co., Ltd.). Examples of the phthalate plasticizer include dibutyl phthalate, diisononyl phthalate, diheptyl phthalate, di(2-ethylhexyl) phthalate, diisodecyl phthalate, and butyl benzyl phthalate. Examples of polycarboxylic acid alkyl ester plasticizers include C3 to C12 alkyl esters of polycarboxylic acids such as diisononyl 1,2-cyclohexanedicarboxylate. Examples of the adipate plasticizer include adipate diesters such as dioctyl adipate and diisononyl adipate. Examples of the sebacic acid ester plasticizer include dioctyl sebacate and diisononyl sebacate. Examples of the polybutadiene-based plasticizer include polybutadiene, its hydrides, derivatives thereof having hydroxyl groups introduced at both ends, and derivatives of these hydrides having hydroxyl groups introduced at both ends. Examples of the polyisoprene-based plasticizer include polyisoprene, its hydrides, derivatives thereof having hydroxyl groups introduced at both ends, and derivatives of these hydrides having hydroxyl groups introduced at both ends. Examples of the polybutene plasticizer include polybutene, its hydrogenated derivatives, derivatives of these having hydroxyl groups introduced at both ends, and derivatives of these hydrogenated derivatives having hydroxyl groups introduced at both ends. Examples of the terpene plasticizer include terpene resins, terpene phenol resins, modified terpene resins, and hydrogenated terpene resins. Examples of the rosin ester resin include disproportionated rosin ester resin, polymerized rosin ester resin, and hydrogenated rosin ester resin. Other plasticizers include phosphate esters such as tricresyl phosphate and tributyl phosphate; trimellitic esters such as trioctyl trimellitate; citric esters such as acetyl tributyl citrate; alkyl esters of polyoxyalkylene glycols such as triethylene glycol bis(2-ethylhexanoate) (for example, C3 to C12 alkyl esters of di-, tri-, or tetraethylene glycol); polyester-based plasticizers such as adipic acid polyesters (excluding adipic acid diesters); epoxy-based ester-based plasticizers; benzoic acid ester-based plasticizers; polyol-based plasticizers such as polyether polyol, polyester polyol, and polycarbonate polyol; thermoplastic elastomers; petroleum resins; alicyclic saturated hydrocarbon resins; and rosin-based resins such as rosin phenol.

[0044] <Silicone resin binder> The silicone resin binder is a silicone resin also called non-reactive diorganopolysiloxane. Examples of the silicone resin include linear diorganopolysiloxane and cyclic diorganopolysiloxane, both of which are end-blocked with trimethylsilyl groups. Examples of the silicone resin binder include methylphenylpolysiloxane end-blocked with trimethylsilyl groups and dimethylpolysiloxane end-blocked with trimethylsilyl groups. Examples of commercially available silicone resins include KF-56 (manufactured by Shin-Etsu Chemical Co., Ltd.). Other examples of the silicone resin include the organopolysiloxane described as component (b) in JP 2001-261765 A.

[0045] <Preferred embodiment> From the viewpoint of compatibility with the resin filler, the binder (A) preferably contains one or more selected from the group consisting of (meth)acrylic resin-based binders, epoxy resin-based binders, and plasticizer-based binders. In addition, the binder (A) is particularly preferably one or more selected from the group consisting of (meth)acrylic resins, epoxy resin-based binders, acrylic polymer-based plasticizers, and benzoic acid ester-based plasticizers. In addition, from the viewpoint of reducing the temperature dependency of the elastic modulus on the low temperature side, the binder (A) also preferably contains a binder having a reactive functional group.

[0046] The value obtained by dividing the viscosity of the binder (A) by the weight average molecular weight of the binder (A) is preferably 0.010 or more and 1.5 or less, and particularly preferably 0.020 or more and 1.0 or less. In addition, from the viewpoint of reducing the temperature dependency of the elastic modulus on the low temperature side, the value obtained by dividing the viscosity of the binder (A) by the weight average molecular weight of the binder (A) is preferably small. In the binder (A-1) and the like, examples of materials having a small value obtained by dividing the viscosity of the binder by the weight average molecular weight of the binder include materials having weak intermolecular interactions. In the case of a material having a weak intermolecular interaction, the viscosity can be reduced even if the molecular weight is the same. For example, by using a component that does not have a hydrogen-bonding functional group (e.g., a urethane bond) or reducing the content of a component having a hydrogen-bonding functional group (e.g., a urethane bond), the viscosity at 25°C can be 20 mPa·s or more and the value obtained by dividing the viscosity of the binder (A) by the weight average molecular weight of the binder (A) can be reduced. In addition, by using a component that does not have an aromatic ring that causes π-π stacking, or by reducing the content of a component that has an aromatic ring, it is possible to achieve a viscosity at 25°C of 20 mPa·s or more and 2,000 mPa·s or less, and to reduce the value obtained by dividing the viscosity of the binder (A) by the weight average molecular weight of the binder (A).

[0047] In addition, the viscosity of the binder (A) at 25°C and the relationship between the viscosity and the weight average molecular weight of the binder (A) can be increased or decreased by using a low-viscosity component (viscosity less than 20 mPa·s at 25°C), a high-viscosity component (viscosity greater than 2,000 mPa·s at 25°C), a binder (A-2) having a weight average molecular weight less than 250, and a binder (A-3) having a weight average molecular weight greater than 1,000. Here, examples of the low-viscosity component include binder (A-1"-2), low-viscosity binder (A-2), and binder (A-3). Examples of the high-viscosity component include binder (A-1"-3), high-viscosity binder (A-2), and binder (A-3).

[0048] Furthermore, when the binder (A-1") contains the binder (A-1"-1), the relationship between the viscosity and the weight average molecular weight of the binder (A) can be made 2 or less by combining the binder (A-1") or the like having a lower viscosity than the binder (A-1"-1).

[0049] The binder (A) may be one component or a combination of two or more components.

[0050] The content of binder (A-1) in binder (A) is not particularly limited as long as the binder (A) has a viscosity of 20 to 2,000 mPa·s at 25°C and satisfies the relationship between molecular weight and viscosity, but is preferably 10 to 100 mass%, more preferably 50 to 100 mass%, and particularly preferably 70 to 100 mass%. Thus, binder (A) may consist of (i) binder (A-1) alone, or may be (ii) a combination of binder (A-1) and one or more selected from the group consisting of binder (A-2) and binder (A-3).

[0051] The content of the binder (A-1') in the binder (A-1) is preferably 10 to 100 mass%, more preferably 30 to 100 mass%, even more preferably 50 to 100 mass%, even more preferably 70 to 100 mass%, and particularly preferably 100 mass%. Thus, the binder (A-1) may consist of (i) only the binder (A-1'), or may be (ii) a combination of the binder (A-1') and the binder (A-1").

[0052] (Resin filler (B)) The resin filler (B) has a glass transition temperature (Tg) of 85°C to 115°C and a weight average molecular weight of 50,000 to 4,000,000, but is not a core-shell type resin filler. The resin filler (B) has a property of swelling in the binder (A) when heated, thereby reducing the fluidity of the thermosetting composition for a dump material.

[0053] The resin filler (B) is not particularly limited, and may be at least one organic filler selected from the group consisting of (meth)acrylic resin filler, sugar compound derivative, styrene resin filler, (meth)acrylic / styrene copolymer filler, polyethylene resin filler, and polypropylene resin filler. The resin filler (B) is preferably a (meth)acrylic resin filler.

[0054] The (meth)acrylic resin filler is a copolymer of (meth)acrylic acid ester monomers, and may be a block copolymer or random copolymer filler. Examples of (meth)acrylic acid ester monomers include (meth)acrylic acid and its derivatives, such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, t-butyl (meth)acrylate, n-octyl (meth)acrylate, dodecyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, stearyl (meth)acrylate, phenyl (meth)acrylate, 2-chloroethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, and diethylaminoethyl (meth)acrylate. The (meth)acrylic resin filler is preferably a copolymer of methyl methacrylate and ethyl methacrylate.

[0055] The resin filler (B) is not a core-shell type resin filler having a core and a shell disposed on the surface of the core. When the resin filler (B) is a core-shell type resin filler, the composition does not cure after heating and has poor thermosetting properties.

[0056] The resin filler (B) has a glass transition temperature (Tg) of 85°C to 115°C. If the resin filler has a Tg of less than 85°C, the storage stability is poor. If the resin filler has a Tg of more than 115°C, the thermosetting property is poor. The resin filler (B) has a Tg of preferably 89°C to 112°C, more preferably 90°C to 105°C, and particularly preferably 95°C to 100°C.

[0057] The weight average molecular weight of the resin filler (B) is 50,000 to 4,000,000, preferably 300,000 to 3,000,000, more preferably 400,000 to 2,000,000, and particularly preferably 500,000 to 1,500,000. When the weight average molecular weight of the resin filler (B) is 50,000 or more, it tends to have excellent thermosetting properties. When the weight average molecular weight of the resin filler (B) is 4,000,000 or less, it tends to have excellent flexibility after curing.

[0058] The resin filler (B) may be one type alone or two or more types in combination.

[0059] (Other Ingredients) The thermosetting composition for dump material may contain other components such as a curing agent, a polymerization inhibitor, an antioxidant, an ultraviolet absorber, a light stabilizer, a thixotropic agent, and a filler within the scope of the effects of the present invention. These specific components may be known components. The thermosetting composition for dump material may also contain a heat curing agent and a light curing agent. When the thermosetting composition for dump material contains both a heat curing agent and a light curing agent, the thermosetting composition for dump material can be a heat and light curing composition for dump material.

[0060] <Antioxidants> Examples of the antioxidant include phenolic antioxidants such as 2,6-di-t-butyl-4-methylphenol, n-octadecyl-3-(4'-hydroxy-3',5'-di-t-butylphenyl)propionate, 2,2'-methylenebis(4-methyl-6-t-butylphenol), and tetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane; sulfuric antioxidants such as dilauryl thiodipropionate, lauryl stearyl thiodipropionate, and pentaerythritol tetrakis(3-lauryl thiopropionate); and phosphorus-based antioxidants such as tris(nonylphenyl)phosphite and tris(2,4-di-t-butylphenyl)phosphite. The phenolic antioxidant can also function as a polymerization inhibitor for acrylic resin binders.

[0061] <Filling agent> The filler is not particularly limited, and examples thereof include known inorganic fillers and organic fillers.

[0062] Examples of inorganic fillers include calcium carbonate, magnesium carbonate, barium sulfate, magnesium sulfate, aluminum silicate, titanium oxide, alumina, zinc oxide, silicon dioxide (precipitated silica, fumed silica, etc.), kaolin, talc, glass beads, sericite activated clay, aluminum hydroxide, asbestos powder, copper oxide, copper hydroxide, iron oxide, lead oxide, magnesium oxide, tin oxide, carbon, mica, smectite, carbon black, bentonite, aluminum nitride, and silicon nitride. From the viewpoint of adhesion, the inorganic filler is preferably silicon dioxide, glass beads, or talc, and more preferably talc.

[0063] Examples of organic fillers include acrylic particles, polymethyl methacrylate, polystyrene (polystyrene beads), copolymers obtained by copolymerizing monomers constituting these (i.e., methyl methacrylate or styrene) with other monomers, polyethylene particles, polysiloxane resin particles, polyamide particles, polyester fine particles, polyurethane fine particles, and rubber fine particles (acrylic rubber particles, isoprene rubber particles). The organic filler may have a core-shell structure. From the viewpoint of adhesion, the organic filler is preferably rubber fine particles, and particularly preferably rubber fine particles having a core-shell structure.

[0064] When the filler is an organic filler, the weight average molecular weight of the organic filler is not particularly limited, but is preferably from 50,000 to 4,000,000, and particularly preferably from 300,000 to 3,000,000.

[0065] The average particle size of the filler is not particularly limited, but is preferably 0.01 μm or more and less than 10 μm, and particularly preferably 1 μm to 5 μm. The average particle size of the filler can be measured by a laser diffraction particle size distribution measuring device.

[0066] The filler may be a component that functions as a thixotropy-imparting agent. The thixotropy-imparting agent is a component that imparts coating properties and the like to the composition. An example of a filler that functions as a thixotropy-imparting agent is fumed silica. The fumed silica may be surface-treated. Examples of surface treatment agents for inorganic thixotropy-imparting agents include monoalkyltrialkoxysilane, dimethyldichlorosilane, polydimethylsiloxane, and hexamethyldisilazane. Surface-treated or untreated fumed silica may be a commercially available product. The fillers may be of one type alone or in combination of two or more types.

[0067] The thermosetting composition for dumping materials preferably contains a filler for maintaining the applied shape, preferably contains a filler that functions as a thixotropic agent, and more preferably contains fumed silica.The thermosetting composition for dumping materials preferably contains an antioxidant for suppressing the change in elastic modulus over time, and more preferably contains a phenolic antioxidant.

[0068] (Composition and characteristics) In the thermosetting composition for dump material, the content of each component is as follows. The content of the resin filler (B) relative to 100 parts by mass of the binder (A) is preferably 1 to 70 parts by mass, more preferably 2 to 50 parts by mass, and particularly preferably 3 to 30 parts by mass. When the content of the resin filler (B) relative to 100 parts by mass of the binder (A) is 1 part by mass or more, the curability is enhanced. When the content of the resin filler (B) relative to 100 parts by mass of the binder (A) is 70 parts by mass or less, the increase in viscosity after mixing the binder (A) and the resin filler (B) is suppressed, thereby improving workability and providing excellent flexibility to the obtained cured product.

[0069] The content of the inorganic filler per 100 parts by mass of the binder (A) is preferably 1 to 70 parts by mass, more preferably 2 to 50 parts by mass, and particularly preferably 3 to 30 parts by mass, from the viewpoints of coatability and shape retention. The content of the antioxidant per 100 parts by mass of the binder (A) is preferably 1 to 70 parts by mass, more preferably 2 to 50 parts by mass, and particularly preferably 3 to 30 parts by mass, from the viewpoint of maintaining viscoelasticity. The total content of the binder (A), the resin filler (B), and, if present, the inorganic filler and the antioxidant, per 100 parts by mass of the thermosetting composition for dumping material, is preferably 70 to 100 parts by mass, and particularly preferably 80 to 100 parts by mass. In the above case, the content of the component having the functions of both an antioxidant and a polymerization inhibitor is defined as the content of the antioxidant.

[0070] (Preparation method) The thermosetting composition for dumping material can be produced by mixing the respective components.

[0071] (Curing method) The thermosetting composition for dump material can quickly form a cured product by heating at a low temperature (for example, 80 to 100° C.) for 3 to 60 minutes.

[0072] (Application) The thermosetting composition for damping materials cures at low temperatures and the cured product has excellent flexibility, so it can be used as a damping material for camera modules, VCMs (Voice Coil Motors), and OISs (Optical Image Stabilizers), which have many components that are sensitive to thermal damage at high temperatures (e.g., above 100°C).

[0073] If the thermosetting composition for dumping materials does not contain components such as thermal initiators, it does not undergo a curing reaction. Therefore, there is no shrinkage due to the curing reaction, and it can be used for fixing camera lenses that require high positional accuracy and for potting without applying stress to components. In addition, the thermosetting composition for dumping materials can be thermally cured at low temperatures (80°C to 100°C) and can be fixed to light-impermeable components without causing thermal damage. EXAMPLES

[0074] The compositions of the Examples and Comparative Examples were produced using the following raw materials. The molecular weight is the weight average molecular weight. The viscosity is a value measured at 25°C.

[0075] (1) Binder (A) (A-1) A binder having a weight average molecular weight of 250 to 1,000 Acrylic resin binder Polyethylene glycol (200) diacrylate (SR259, manufactured by Arkema. Molecular weight: 302. Viscosity: 25 mPa·s.) This component has a polyethylene glycol repeating number of 4. Ethoxylated (3) Trimethylolpropane triacrylate (SR454, manufactured by Arkema. Molecular weight 428. Viscosity 60 mPa·s.) This component is a triacrylate having 3 moles of ethylene oxide units per mole of trimethylolpropane. Ethoxylated (6) Trimethylolpropane triacrylate (SR499, manufactured by Arkema. Molecular weight: 560. Viscosity: 95 mPa·s.) This component is a triacrylate having 6 moles of ethylene oxide units per mole of trimethylolpropane. Ethoxylated (9) Trimethylolpropane triacrylate (SR502, manufactured by Arkema. Molecular weight: 692. Viscosity: 130 mPa·s.) This component is a triacrylate having 9 moles of ethylene oxide units per mole of trimethylolpropane. Urethane acrylate (UN-2301, manufactured by Negami Chemical Industries, Ltd.; molecular weight 740; viscosity 9,300 mPa s.) Plasticizer-based binder Benzoate ester plasticizer (PB-3A, manufactured by DIC. Molecular weight: 320. Viscosity: 100 mPa s.) (A-2) A binder having a weight average molecular weight of less than 250 Epoxy binder 3-Glycidoxypropyltrimethoxysilane (KBM403, manufactured by Shin-Etsu Chemical Co., Ltd.; molecular weight: 236; viscosity: 10 mPa·s) (A-3) Binder with a weight average molecular weight of more than 1,000 Plasticizer-based binder Acrylic polymer plasticizer (UP1061, manufactured by Toagosei Co., Ltd.; molecular weight 1,600; viscosity 550 mPa s)

[0076] (2) Resin filler (B) Methyl methacrylate / ethyl methacrylate copolymer (SD-350ME, manufactured by Negami Chemical Industries, Ltd. Molecular weight: 1 million. Tg: 98°C.) (3) Additives (C) TG-308F: Fumed silica (manufactured by CABOT) AO80: Phenolic antioxidant (ADEKA)

[0077] The compositions of Examples 1-9 and Comparative Examples 1-3 were prepared by mixing the ingredients in the amounts (parts by mass) shown in the table below and stirring with a stirrer (RW28 (IKA), 600 rpm).

[0078] 〔evaluation〕 (1) Viscosity and thixotropy The viscosity of binder (A) (when multiple binders are present, the binder composition including all binders) was measured at 25°C using a viscometer: Toki RE-215S, measurement conditions: 3°×R14 rotor, 10 rpm, 25±1°C (low viscosity: 3°×R24 rotor, 10 rpm, 25±1°C). The viscosity shown in the table is the value at 10 rpm. The thixotropy ratio is the value obtained by measuring the viscosity at 1 rpm and calculating "thixotropy ratio = (viscosity at 1 rpm / viscosity at 10 rpm)".

[0079] (2) Thermosetting The composition was applied onto a slide glass and heated in an oven at 80° C. for 1 hour. The thermosetting property of the composition was judged by touch and evaluated according to the following criteria. ○: Cured at 80℃ for 1 hour ×: Not cured at 80℃ for 1 hour

[0080] (3) Liquid stability (storage stability) The viscosity of the thermosetting composition after preparation was compared to the viscosity of the composition after storage at 25° C. for 24 hours. ○: Viscosity change rate was 10% or less ×: Viscosity change rate was more than 10%

[0081] (4) Shape retention 5 mg of the composition was applied onto a slide glass, the slide glass was propped up and left for 1 minute, and the shape was confirmed. ○: No dripping ×: Dripping

[0082] (5) Rheometer Rheometer: Thermo Scientific HAAKE RheoStress6000 (parallel plate: PP20E (φ20 mm), measurement thickness: 0.5 mmt, 25° C., 1 Hz) was used. (5-1) Temperature conditions (5-1-1) Example 1 (i) A gel of the composition having a thickness of 0.5 mm was prepared on a stage in advance under the curing conditions of 80° C. and 60 minutes. (ii) The temperature was increased from 25°C to 80°C at a rate of 10°C / min. (iii) The temperature was lowered from 80°C to -20°C at a rate of 3°C / min. The storage modulus and tan δ were read at -20°C, 25°C, and 80°C. (5-1-2) Examples 2 to 9 and Comparative Examples 1 to 2 The measurement frequency was fixed at 1 Hz, and the processing was carried out in the following order (i) to (iii). (i) The temperature was increased from 25°C to 80°C at a rate of 10°C / min. (ii) The composition was cured by holding at 80°C for 60 minutes. (iii) The temperature was decreased from 80° C. to −20° C. at a rate of 3° C. / min. The storage modulus and tan δ values ​​were read at -20°C, 25°C, and 80°C.

[0083] (5-2) Evaluation From the storage modulus readings at -20°C, 25°C, and 80°C, the ratio of the storage modulus at -20°C to the storage modulus at 25°C (storage modulus at -20°C ÷ storage modulus at 25°C) and the ratio of the storage modulus at 25°C to the storage modulus at 80°C (storage modulus at 25°C ÷ storage modulus at 80°C) were calculated. ○: The storage modulus ratio was 0.1 or more and less than 10. ×: The ratio of storage elastic modulus was 10 or more.

[0084] The above results are summarized in Table 1. The "molecular weight of binder (A)" is the weighted average of the molecular weights of the binder components contained in the composition.

[0085] [Table 1]

[0086] The composition of the embodiment was cured under the heat curing condition of 80°C for 1 hour, and had excellent heat curing properties. In addition, the composition of the embodiment had little change in viscosity at 25°C for 24 hours, and had excellent storage stability. In addition, the composition of the embodiment had small temperature dependence of the elastic modulus at low temperatures (i.e., the ratio of the storage elastic modulus at -20°C to the storage elastic modulus at 25°C) and small temperature dependence of the elastic modulus at high temperatures (i.e., the ratio of the storage elastic modulus at 25°C to the storage elastic modulus at 80°C), and in particular, the temperature dependence of the elastic modulus at low temperatures was small. From the results of Examples 1 and 2, when the thermosetting composition for dump material further contains a filler, the shape retention was excellent, and when the thermosetting composition for dump material further contains an antioxidant, the temperature dependence of the elastic modulus at low temperatures was smaller. In addition, from the results of the embodiment, when the value when the viscosity of the binder divided by the weight average molecular weight of the binder was small, there was a tendency that the temperature dependence of the elastic modulus at low temperatures was small. Comparing Examples 4, 5, 7, and 9 with Example 6, it was found that when the thermosetting composition for dump material contains a binder having a reactive functional group, the temperature dependence of the elastic modulus at low temperatures tended to be smaller.

[0087] In Comparative Example 1, the viscosity of the entire binder exceeded 2,000 mPa·s, so the temperature dependency of the elastic modulus at low temperatures became large. In Comparative Example 2, the viscosity of the binder was less than 20 mPa·s, so the storage stability was poor. In Comparative Example 3, the weight average molecular weight of the binder exceeded 1,000, so the thermosetting property was poor. On the other hand, according to the results of Examples 7 to 9, even when the components used in Comparative Example 1 and the components used in Comparative Examples 2 and 3 were included, the binder (A-1) having a weight average molecular weight of 250 to 1,000 was included, the viscosity of the entire binder was 2,000 mPa·s or less, and the value obtained by dividing the viscosity of the binder by the weight average molecular weight of the binder was 2 or less, so the effects of the present invention were achieved.

Claims

1. A thermosetting composition for a dump material, comprising a binder (A) and a resin filler (B), the binder (A) includes a binder (A-1) having a weight average molecular weight of 250 to 1,000, the binder (A-1) being at least one selected from the group consisting of (meth)acrylic resin-based binders and plasticizer-based binders, the binder (A) having a viscosity of 20 to 2,000 mPa s at 25°C, wherein the value obtained by dividing the viscosity of the binder (A) by the weight average molecular weight of the binder (A) is 2 or less, The thermosetting composition for a dump material, wherein the resin filler (B) is a (meth)acrylic resin filler, the glass transition temperature (Tg) of the resin filler (B) is 85°C to 115°C, and the weight average molecular weight of the resin filler (B) is 50,000 to 4,000,000, but the resin filler (B) is not a core-shell type resin filler.

2. The binder (A) further comprises a binder (A-2) having a weight average molecular weight of less than 250, and / or a binder (A-3) having a weight average molecular weight of more than 1,000, and the binder (A-2) and the binder (A-3) are each independently selected from (meth)acrylic resin-based binders, epoxy resin-based binders, silicone resin-based binders and plasticizer-based binders. The thermosetting composition for dump materials according to claim 1.

3. The thermosetting composition for dump material according to claim 1 or 2, wherein the viscosity of the binder (A) at 25°C is 20 mPa·s or more and less than 700 mPa·s.

4. The thermosetting composition for dump material according to any one of claims 1 to 3, further comprising one or more selected from the group consisting of fillers and antioxidants.

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