Photocurable resin composition

Abstract

To provide a resin composition which is capable of being cured to a deep region upon irradiation with an energy ray and which exhibits high density.SOLUTION: The present invention relates to a photocurable resin composition comprising an epoxy resin (A), an inorganic filler (B), and a thiol-based curing agent (C) and / or a cationic polymerization initiator (D), wherein a content of the component (B) is 50 to 2,500 pts.mass relative to 100 pts.mass of the component (A).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a photocurable resin composition. [Background technology]

[0002] If the rotating body of a rotating electrical device such as a motor is not perfectly balanced, a lot of vibration occurs during rotation. As a method for adjusting the balance, a resin composition for balancing is attached as a weight to achieve the weight balance.

[0003] Patent Document 1 discloses that a thermosetting epoxy resin composition containing an epoxy resin, an inorganic filler, a latent curing agent such as a hydrazide compound, and a curing accelerator which is an imidazole compound is used as a resin composition for balance adjustment.

[0004] When a thermosetting resin composition is cured by heating, the viscosity of the resin decreases due to the initial heat generated during the curing process, which can cause the liquid to drip or spread, resulting in a change in the coating shape before and after curing. Furthermore, when a thermosetting resin composition is cured by heating, a heating oven is required. Therefore, curing by light (energy rays) may be required as a method for curing an epoxy resin composition. For example, Patent Document 2 discloses curing an epoxy resin composition by light irradiation. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 63-311 [Patent Document 2] Japanese Patent Publication No. 2020-45435 Summary of the Invention [Problem to be solved by the invention]

[0006] With the epoxy resin composition disclosed in Patent Document 1, it was sometimes difficult to cure it to a deep portion by irradiation with energy rays alone. Furthermore, when used as a resin composition for balance adjustment, it is required to have a high specific gravity. However, with the resin composition not containing an inorganic filler, such as that disclosed in Patent Document 2, it was sometimes difficult to achieve a high specific gravity.

[0007] An object of the present invention is to provide a resin composition that can be cured to a deep portion by irradiation with energy rays and has a high specific gravity. [Means for solving the problem]

[0008] The present invention relates to the following: [1] A photocurable resin composition comprising an epoxy resin (A), an inorganic filler (B), a thiol-based curing agent (C) and / or a thermal cationic polymerization initiator (D), in which the content of component (B) is 50 to 2,500 parts by mass per 100 parts by mass of component (A). [2] The photocurable resin composition according to [1], which is cured by irradiation with light having a wavelength in the range of 300 to 800 nm. [3] The photocurable resin composition according to [1] or [2], wherein the component (B) has a thermal conductivity of 30 to 450 W / m·K. [4] The specific gravity of component (B) is 3.0 to 20.0 g / cm 3 The photocurable resin composition according to any one of [1] to [3], wherein [5] The photocurable resin composition according to any one of [1] to [4], which contains component (C), and in which the equivalent ratio (epoxy:thiol) of the epoxy groups of component (A) to the thiol groups of component (C) is 0.3:1.0 to 1.0:0.3. [6] The photocurable resin composition according to any one of [1] to [5], which contains component (D), and the content of component (D) is 1 to 10 parts by mass per 100 parts by mass of component (A). [7] The photocurable resin composition according to any one of [1] to [6], further comprising one or more selected from the group consisting of a curing accelerator and carbon black. [8] The photocurable resin composition according to any one of [1] to [7], which is used to form a balance weight for a rotating body. [9] A method for manufacturing a rotating body including a balance weight, comprising: a step of applying the photocurable resin composition according to any one of [1] to [7] to a rotating body; A manufacturing method comprising the step of irradiating a photocurable resin composition with light having a wavelength in the range of 300 to 800 nm to cure the composition, and forming a balance weight, which is a cured product of the photocurable resin composition, on a rotating body. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a resin composition that can be cured to a deep portion by irradiation with energy rays and has a high specific gravity. DETAILED DESCRIPTION OF THE INVENTION

[0010] [Term definition] "Epoxy resin (A)" is also referred to as "component (A)." The same applies to "inorganic filler (B)," etc. With regard to numerical ranges, "to" means that both ends of the range are included. Also, "less than" means "the same as or less than," and "more than" means "the same as or greater than."

[0011] [Photocurable resin composition] The photocurable resin composition contains an epoxy resin (A), an inorganic filler (B), a thiol-based curing agent (C) and / or a thermal cationic polymerization initiator (D), and the content of component (B) is 50 to 2,500 parts by mass per 100 parts by mass of component (A).

[0012] The photocurable resin composition can be cured to its depths by irradiation with energy rays. That is, the photocurable resin composition has deep curing properties. Furthermore, the photocurable resin composition uses a light source as a heat source. That is, when irradiated with light, the inorganic filler (B) absorbs the light and generates heat. This heat heats the interior of the photocurable resin composition, which is not penetrated by light. This heating activates the heat curing catalyst (i.e., the thiol-based curing agent (C) and / or the thermal cationic polymerization initiator (D)), and the curing reaction progresses to the interior of the photocurable resin composition. This gives the photocurable resin composition curability.

[0013] <Epoxy resin (A)> The epoxy resin (A) is a resin having one or more epoxy groups in the molecule. Examples of the component (A) include aromatic epoxy resins, aliphatic epoxy resins, and alicyclic epoxy resins.

[0014] Examples of aromatic epoxy compounds include bisphenol A epoxy resins (such as EPICLON 850, 850-S, EXA-850CRP, and EXA-8067 manufactured by DIC Corporation), bisphenol F epoxy resins (such as EPICLON 830-S and EXA-830LVP manufactured by DIC Corporation), bisphenol AD ​​epoxy resins, bisphenol S epoxy resins, naphthalene epoxy resins (such as EPICLON HP-4032D and HP-7200H manufactured by DIC Corporation), phenol novolac epoxy resins (such as EPICLON N-740 and N-770 manufactured by DIC Corporation), cresol novolac epoxy resins (such as EPICLON N-660, N-670, and N-655-EXP-S manufactured by DIC Corporation), and multifunctional epoxy resins. Examples of polyfunctional epoxy compounds include glycidyl ethers of tetra(hydroxyphenyl)alkanes, glycidyl ethers of tetrahydroxybenzophenones, and epoxidized polyvinylphenols.

[0015] Examples of aliphatic epoxy resins include polyglycidyl ethers of polyhydric alcohols or their alkylene oxide adducts. Specific examples of aliphatic epoxy compounds include ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin diglycidyl ether, trimethylolpropane triglycidyl ether (Epolite 100MF manufactured by Kyoeisha Chemical Co., Ltd.), polyethylene glycol diglycidyl ether, and 1,2-epoxy-4-(2-oxiranyl)cyclohexane adduct of 2,2-bis(hydroxymethyl)-1-butanol (EHPE3150 manufactured by Daicel Corporation).

[0016] Aliphatic epoxy resins are resins with a structure in which an epoxy group is formed by two carbon atoms and an oxygen atom forming an alicyclic structure. Aliphatic epoxy resins in which an epoxy group is bonded to one carbon atom forming the alicyclic structure are not included. Examples of alicyclic epoxy compounds include cyclohexane-based, cyclohexyl methyl ester-based, cyclohexyl methyl ether-based, spiro-based, and tricyclodecane-based epoxy compounds. Specific examples of alicyclic epoxy compounds include (3,3',4,4'-diepoxy)bicyclohexyl (e.g., Celloxide 8010 manufactured by Daicel Corporation), 3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (e.g., Celloxide 2021P manufactured by Daicel Corporation), 1,2:8,9-diepoxylimonene, and 1,2-epoxy-4-vinylcyclohexane.

[0017] Component (A) may be one type or a combination of two or more types.

[0018] <Inorganic filler (B)> Examples of the inorganic filler (B) include metal fillers, metal oxide fillers, and other inorganic fillers.

[0019] Examples of the metal filler include Ag, Cu, Au, Al, Mg, Rh, W, Mo, Co, Ni, Pt, Pd, Cr, Ta, Pb, V, Zr, Ti, In, Fe, and Zn.

[0020] Examples of the metal oxide filler include fillers of metal oxides such as aluminum oxide, silicon oxide, zirconium oxide, titanium oxide, zinc oxide, tin oxide, and indium oxide.

[0021] Other inorganic fillers include clay mineral fillers such as talc, kaolinite, and smectite; nitride fillers such as silicon nitride, aluminum nitride, and titanium nitride; boride fillers such as boron nitride, titanium boride, and boron oxide; and hydroxide fillers such as aluminum hydroxide and magnesium hydroxide.

[0022] From the viewpoint of efficiently transferring heat into the photocurable resin composition when component (B) absorbs light and generates heat, the thermal conductivity of component (B) is preferably 30 to 450 W / m K, and particularly preferably 100 to 450 W / m K. The thermal conductivity of component (B) can be measured by the flash method or the temperature gradient method.

[0023] From the viewpoint of efficiently increasing the specific gravity of the photocurable resin composition, the specific gravity of the component (B) is 3.0 to 20.0 g / cm 3 is preferably 8.0 to 20.0 g / cm 3 Here, the specific gravity of component (B) can be measured in accordance with JIS K 6833.

[0024] The average particle size of component (B) is not particularly limited. From the viewpoint of efficient light absorption and efficient heat generation, the average particle size of component (B) is preferably in the range of 0.1 to 50 μm, and particularly preferably in the range of 0.5 to 10 μm. Here, the average particle size of component (B) can be measured using a laser diffraction particle size distribution analyzer.

[0025] Component (B) is preferably one or more selected from the group consisting of metal fillers and metal oxide fillers. Component (B) may be one type or a combination of two or more types.

[0026] <Thiol-based curing agent (C) and / or thermal cationic polymerization initiator (D)> The photocurable resin composition contains a thiol-based curing agent (C) and / or a thermal cationic polymerization initiator (D). The photocurable resin composition may contain component (C) but not component (D). The photocurable resin composition may contain component (D) but not component (C). Alternatively, the photocurable resin composition may contain both component (C) and component (D).

[0027] <Thiol-based curing agent (C)> The thiol curing agent (C) is not particularly limited as long as it is a compound having one or more thiol groups (mercapto groups, -SH groups) in the molecule. Examples of compounds having one thiol group in the molecule include alkanethiols. Examples of compounds having two or more thiol groups in the molecule include polythiol compounds.

[0028] The alkanethiol is preferably a linear or branched alkanethiol having 6 to 20 carbon atoms. Examples of such alkanethiols include 1-hexanethiol, 1-heptanethiol, 1-octanethiol, tert-octanethiol, 1-nonanethiol, 1-decanethiol, 1-undecanethiol, 1-dodecanethiol, 1-tetradecanethiol, 1-hexadecanethiol, and 1-octadecanethiol.

[0029] Polythiol compounds include 3,3'-dithiodipropionic acid, trimethylolpropane tris(thioglycolate), pentaerythritol tetrakis(thioglycolate), ethylene glycol dithioglycolate, 1,4-bis(3-mercaptobutyryloxy)butane, tris[(3-mercaptopropionyloxy)-ethyl]-isocyanurate (TEMPIC), 1,3,5-tris(3-mercaptobutyloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, trimethylolpropane tris(3-mercaptopropionate) (TMMP), and pentaerythritol tetrakis(3-mercaptopropionate) (PEM thiol compounds obtained by an esterification reaction between a polyol, such as dipentaerythritol tetrakis(3-mercaptobutyrate) (DPMP), pentaerythritol hexakis(3-mercaptopropionate) (DPMP), and a mercapto organic acid; linear or branched alkanedithiols having 4 to 20 carbon atoms, such as 1,4-butanedithiol, 1,6-hexaneedithiol, and 1,10-decanedithiol; polyethers containing terminal thiol groups; polythioethers containing terminal thiol groups; thiol compounds obtained by the reaction of an epoxy compound with hydrogen sulfide; and thiol compounds having terminal thiol groups obtained by the reaction of a polythiol compound with an epoxy compound.

[0030] The polythiol compound is preferably 1,4-bis(3-mercaptobutyryloxy)butane, tris[(3-mercaptopropionyloxy)-ethyl]-isocyanurate (TEMPIC), 1,3,5-tris(3-mercaptobutyloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, trimethylolpropane tris(3-mercaptopropionate) (TMMP), pentaerythritol tetrakis(3-mercaptopropionate) (PEMP), pentaerythritol tetrakis(3-mercaptobutyrate), or dipentaerythritol hexakis(3-mercaptopropionate) (DPMP).

[0031] From the viewpoints of suppressing the odor of the thiol compound and improving workability, component (C) is preferably a compound having three or more mercapto groups in the molecule, and particularly preferably a compound having four to six mercapto groups in the molecule. Component (C) may be one type or a combination of two or more types.

[0032] <Thermal cationic polymerization initiator (D)> The thermal cationic polymerization initiator (D) is a component that serves as a cation generation source when cationic polymerization is carried out by heat.

[0033] The thermal cationic polymerization initiator has a cation moiety that is an aromatic sulfonium cation, an aromatic diazonium cation, an aromatic ammonium cation, an iodonium cation, a thianthrhenium cation, a thioxanthonium cation, or a (2,4-cyclopentadien-1-yl)[(1-methylethylbenzene]-Fe cation, and an anion moiety that is SbF6 - , BF4 - , PF6 - , B(C6F5)4 - , [P(R F ) n F 6-n ] - (In the formula, R F are independently a partially or fully fluorinated alkyl group having 1 to 6 carbon atoms, and n is an integer of 0 to 5), or [BX4] - (wherein X is a phenyl group substituted with at least two fluorine atoms or trifluoromethyl groups). The thermal cationic polymerization initiator is preferably a sulfonium salt. The anion of the thermal cationic polymerization initiator is preferably SbF6 - , B(C6F5)4 - , or [P(R F ) n F 6-n ] - (In the formula, R F are preferably independently a partially or fully fluorinated alkyl group having 1 to 6 carbon atoms, and n is an integer of 0 to 5).

[0034] Commercially available products of component (D) include TA-60, TA-60B, TA-100, and TA-120 manufactured by San-Apro Co., Ltd.; Adeka Opton CP-77 and Adeka Opton CP-66 manufactured by ADEKA Corporation; CI-2639 and CI-2624 manufactured by Nippon Soda Co., Ltd.; CXC-1612 and CXC-1738 manufactured by King Industries Co., Ltd.; and San-Aid SI-45, San-Aid SI-60, San-Aid SI-80, San-Aid SI-100, San-Aid SI-110, San-Aid SI-B3, San-Aid SI-B3A, and San-Aid SI-B4 manufactured by Sanshin Chemical Industry Co., Ltd. Component (D) may be one type or a combination of two or more types.

[0035] <Additional Ingredient (E)> The photocurable resin composition may further contain component (E) depending on the purpose, as long as the effect of the present invention is not impaired. Examples of component (E) include a curing accelerator, carbon black, a silane coupling agent, a surfactant, a polymerization inhibitor, a photosensitizer, an antioxidant, a stabilizer, a colorant, and a solvent.

[0036] Examples of the curing accelerator include imidazole compounds, tertiary amine compounds, organic peroxides, phosphines, organic metal salts, and metal chlorides.

[0037] Examples of the imidazole compound include 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-phenylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, and 1-cyanoethyl-2-undecylimidazole. Examples thereof include imidazole, 1-cyanoethyl-2-phenylimidazole, 2,4-diamino-6-(2-methylimidazolylethyl)-1,3,5-triazine, 2,4-diamino-6-(2-undecylimidazolylethyl)-1,3,5-triazine, 2,4-diamino-6-(2-ethyl-4-methylimidazolylethyl)-1,3,5-triazine, 2-phenyl-4,5-dihydroxymethylimidazole, and 2-phenyl-4-methyl-5-hydroxymethylimidazole.

[0038] Examples of tertiary amine compounds include lauryldimethylamine, dimethylcyclohexylamine, dimethylbenzylamine, dimethylaminomethylphenol, 2,4,6-tris(N,N-dimethylaminomethyl)phenol, 1,4-diazabicyclo[2.2.2]octane, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), and 1,5-diazabicyclo[4.3.0]non-5-ene (DBN).

[0039] Examples of organic peroxides include ketone peroxides, peroxyketals, diacyl peroxides, peroxyesters, peroxydicarbonates, etc. Commercially available organic peroxides include t-hexyl peroxy-2-ethylhexanoate (Perhexyl (registered trademark) O) and t-butyl peroxy-2-ethylhexanoate (Pertible (registered trademark) O) manufactured by NOF Corporation.

[0040] Curing accelerators other than those mentioned above can be appropriately selected from known components used in epoxy resin compositions.

[0041] The curing accelerator is preferably an imidazole compound and / or a tertiary amine compound, and particularly preferably an imidazole compound.

[0042] The carbon black can be appropriately selected from known components.

[0043] The component (E) other than those mentioned above can be appropriately selected from known components used in epoxy resin compositions.

[0044] The photocurable resin composition preferably further contains one or more selected from the group consisting of a curing accelerator and carbon black. When the photocurable resin composition contains component (C), it is particularly preferable that the composition further contains a curing accelerator.

[0045] (characteristic) The viscosity of the photocurable resin composition at 25°C is preferably 1,000 to 200,000 mPa·s, and particularly preferably 10,000 to 100,000 mPa·s. When the viscosity of the photocurable resin composition at 25°C is 1,000 to 200,000 mPa·s, the photocurable resin composition tends to be more stable at the applied position. Furthermore, when the viscosity is within this range, the dispersibility of component (B) in the photocurable resin composition tends to be good. Here, the viscosity is measured using an E-type viscometer at atmospheric pressure at 25°C, with an appropriate cone plate and rotation speed selected.

[0046] (Content of each ingredient) In the photocurable resin composition, the content of each component is as follows.

[0047] The content of component (B) is 50 to 2,500 parts by mass per 100 parts by mass of component (A). If the content of component (B) is less than 50 parts by mass per 100 parts by mass of component (A), the specific gravity of the photocurable resin composition tends to be low. If the content of component (B) is more than 2,500 parts by mass per 100 parts by mass of component (A), the deep section curing property tends to be poor. The content of component (B) is preferably 50 to 2,500 parts by mass, and particularly preferably 400 to 1,000 parts by mass per 100 parts by mass of component (A). When the content of component (B) is within the above range, the specific gravity of the photocurable resin composition tends to be efficiently increased, the flowability of the photocurable resin composition tends to be further improved, and / or the deep section curing property tends to be further enhanced.

[0048] In addition to the above, the content of component (B) is preferably 20 to 85 parts by mass, more preferably 50 to 85 parts by mass, and particularly preferably 70 to 85 parts by mass, per 100 parts by mass of the photocurable resin composition. When the content of component (B) is within the above range, the specific gravity of the photocurable resin composition tends to increase efficiently, the flowability of the photocurable resin composition tends to be further improved, and / or the deep curability tends to be further enhanced.

[0049] When the photocurable resin composition contains component (C), from the viewpoint of toughness of the cured product, the equivalent ratio of the epoxy groups of component (A) to the thiol groups of component (C) (epoxy:thiol) is preferably 0.3:1.0 to 1.0:0.3, and particularly preferably 0.8:1.0 to 1.0:0.8.

[0050] When the photocurable resin composition contains component (D), from the viewpoint of curability, the content of component (D) is preferably 1 to 10 parts by mass, and particularly preferably 1 to 5 parts by mass, per 100 parts by mass of component (A).

[0051] The total content of component (A), component (B), component (C), and component (D) relative to 100 parts by mass of the photocurable resin composition is preferably 55 parts by mass or more and 100 parts by mass or less, more preferably 70 parts by mass or more and 98 parts by mass or less, and particularly preferably 80 parts by mass or more and 97 parts by mass or less.

[0052] (Method of producing photocurable resin composition) The photocurable resin composition can be obtained by a production method including a step of mixing component (A), component (B), component (C) and / or component (D), and optional component (E).

[0053] (Method for curing photocurable resin composition) The photocurable resin composition can be cured by irradiating it with energy rays. The energy rays are not particularly limited, and active energy rays such as visible light, ultraviolet rays, X-rays, and electron beams can be used.

[0054] The light source of the energy ray can be a light source that emits each type of energy ray, such as a metal halide lamp, a high-pressure mercury lamp, a xenon lamp, a mercury-xenon lamp, a halogen lamp, a pulse xenon lamp, and an LED.

[0055] From the viewpoint of the light absorption efficiency and heat generation efficiency of component (B) (i.e., the inorganic filler), the photocurable resin composition is preferably cured by irradiation with light having a wavelength of 300 to 800 nm, and particularly preferably by irradiation with light having a wavelength of 300 to 700 nm. When light having a wavelength of 300 to 800 nm is used, component (B) efficiently absorbs the 300 to 800 nm light and generates heat, so that even areas where the light is not transmitted are heated. This results in superior rapid curing properties and / or superior deep curing properties. In the present invention, it is believed that when the inorganic filler (B) absorbs light and generates heat, it efficiently absorbs light having a wavelength of 450 to 800 nm within the 300 to 800 nm range. Therefore, light having a wavelength of 300 to 450 nm within the 300 to 800 nm range may be blocked by a filter or the like.

[0056] The cumulative light amount of the energy rays is, for example, 1,000 to 50,000 mJ / cm at 365 nm. 2 It is preferable that the concentration is 10,000 to 40,000 mJ / cm 2 It is particularly preferred that:

[0057] [Application] Because the photocurable resin composition has a high specific gravity, it can be used as a photocurable resin composition for a balance weight. The photocurable resin composition for a balance weight is preferably a photocurable resin composition used to form a balance weight for a rotating body. The balance weight for a rotating body refers to a cured product of the photocurable resin composition present in an amount sufficient to offset the imbalance in rotation of the rotating body.

[0058] Examples of rotating bodies include rotating disks in HDDs (hard disk drives), rotors for motors, rolling mill rolls, rotary tools, shafts for various machines, rotors for motors such as brushless outer rotor motors and brush motors, and polygon mirrors for laser printers.

[0059] When the photocurable resin composition is used as a photocurable resin composition for a balance weight, a rotating body including the balance weight can be manufactured. The manufacturing method of the rotating body including the balance weight includes, for example, the following steps: A step of applying a photocurable resin composition to a rotating body; A step of irradiating the photocurable resin composition with energy rays to cure the composition, thereby forming a balance weight, which is a cured product of the photocurable resin composition, on the rotating body. Includes.

[0060] In the step of applying the photocurable resin composition to the rotating body, the application location and application method of the photocurable resin composition can be appropriately determined depending on the shape of the target rotating body. In the step of forming the balance weight, the method of curing the photocurable resin composition is as described above. In the step of forming the balance weight, the wavelength of the energy ray used is preferably in the range of 300 to 800 nm, and particularly preferably in the range of 300 to 700 nm.

[0061] In addition, for methods of manufacturing a rotating body including a balance weight, reference can be made to the descriptions in Japanese Patent Application Laid-Open Nos. 8-104705, 5-180273, 5-38092, 2001-37174, 2008-61354, and 2021-156413. [Example]

[0062] Examples are given below to clarify specific embodiments of the present invention, but the present invention is not limited to the examples shown here.

[0063] Each composition of the examples and comparative examples was produced using the following raw materials. 1. Component (A): Epoxy resin Bisphenol A epoxy resin (DIC, EPICLON EXA-850CRP)

[0064] 2. Component (B): Inorganic filler Tungsten (specific gravity: 19.3 g / cm 3 , Thermal conductivity: 180W / m·K, W-4 manufactured by Nippon Shinkinzoku Co., Ltd. Alumina (specific gravity: 3.97 g / cm 3 , thermal conductivity: 40W / m K, Sumitomo Chemical Co., Ltd. AA-18)

[0065] 3. Component (C): Thiol-based curing agent Pentaerythritol tetrakis(3-mercaptopropionate) (PEMP) (SC Organic Chemicals)

[0066] 4. Component (D): Thermal cationic polymerization initiator Benzylmethyl p-hydroxyphenylsulfonium hexafluoroantimonate (Sanshin Chemical Industry Co., Ltd., San-Aid SI-100L (γ-butyrolactone solution)).

[0067] 5. Ingredient (E): Other ingredients Curing accelerator: Imidazole curing agent (Asahi Kasei Corporation, Novacure HXA9322HP) Carbon black: Carbon black (Mitsubishi Chemical, Mitsubishi Carbon Black #2650)

[0068] [Production method] The components were mixed and stirred using a planetary stirrer in the proportions (parts by mass) shown in the table to prepare compositions of the examples and comparative examples.

[0069] [Evaluation conditions] 1. Viscosity The viscosity of the composition was measured using an E-type viscometer (RE-125U manufactured by Toki Sangyo Co., Ltd.) at 25°C using a 3°×R14 rotor at a rotation speed of 5 rpm.

[0070] 2.Curability 20 mg of the composition was applied to a plastic sheet (Polyamide LA121 manufactured by Kuraray Co., Ltd., 10 mm long x 10 mm wide x 3 mm thick), and then irradiated at 2,000 mW / cm with an irradiator (irradiator (1): SP-11 manufactured by Ushio Inc. or irradiator (2): LC-8 (L9588-01) manufactured by Hamamatsu Photonics K.K.). 2The composition was irradiated for 10 seconds or 20 seconds. The irradiator (1) emitted light with a wavelength in the range of 300 to 750 nm. The irradiator (2) was set to emit light with a wavelength of 250 to 450 nm. The illuminance meter used was a C6080-13 manufactured by Hamamatsu Photonics KK It was confirmed whether the composition had cured, and the curability was evaluated according to the following criteria. ○: Hardened ×: Uncured

[0071] 3. Deep hardening The liquid (composition) was filled into a black tube with an inner diameter of 5 mm and a height of 5 mm. The liquid was irradiated at 2,000 mW / cm using a UV irradiator (irradiator (1): SP-11 manufactured by Ushio Inc. or irradiator (2): LC-8 (L9588-01) manufactured by Hamamatsu Photonics K.K.). 2 The curing depth was measured using a micrometer.

[0072] 4.Specific gravity The specific gravities of the composition and filler were measured according to JIS K6833 (specific gravity cup method). When a catalog value for the specific gravity of the filler was available, the catalog value was used.

[0073] 5. Thermal Conductivity The thermal conductivity of the filler was determined using the catalog value.

[0074] The results are summarized in the table below. Note that "-" in each measurement result indicates that the measurement was not performed.

[0075] [Table 1]

[0076] The photocurable resin compositions of Examples 1 to 9 were excellent in curability and deep curability. Furthermore, the photocurable resin compositions of Examples 1 to 9 had a high specific gravity. Furthermore, the photocurable resin compositions of Examples 1 to 9 were excellent in curability when irradiated with light having a wavelength in the range of 300 to 800 nm.

[0077] In particular, a comparison of Examples 1, 3 to 6 shows that the viscosity increased as the content of component (B) increased. Furthermore, a comparison of Examples 1, 3 to 6 shows that when the content of component (B) was 50 to 250 parts by mass per 100 parts by weight of component (A), the deep section curing was superior. A comparison of Examples 7 and 8 shows that when the component (E) which is carbon black is further contained, the curability was even better. A comparison between Examples 3 and 7 shows that when tungsten was used as component (B), the deep section hardening was superior. A comparison of Examples 5 and 9 revealed that the deep curing properties were superior when component (C) was included compared to when component (D) was included.

[0078] Comparative Examples 1 and 2 did not contain component (B), and therefore exhibited poor curability. The light source used in Comparative Example 2 emitted light with a wavelength of 250 to 450 nm, and the composition contained component (C), but the curability of the resin composition was poor. Comparative Example 3 did not contain either component (C) or component (D), and therefore exhibited poor curability.

Claims

1. A photocurable resin composition comprising an epoxy resin (A), an inorganic filler (B), and a thiol-based curing agent (C) and / or a thermal cationic polymerization initiator (D), wherein the content of component (B) is 50 to 2,500 parts by mass per 100 parts by mass of component (A).

2. The photocurable resin composition according to claim 1, which is cured by irradiation with light having a wavelength in the range of 300 to 800 nm.

3. 2. The photocurable resin composition according to claim 1, wherein the thermal conductivity of component (B) is 30 to 450 W / m·K.

4. The specific gravity of component (B) is 3.0 to 20.0 g / cm ３ The photocurable resin composition according to claim 1, wherein

5. 2. The photocurable resin composition according to claim 1, comprising component (C), wherein the equivalent ratio (epoxy:thiol) of the epoxy groups of component (A) to the thiol groups of component (C) is 0.3:1.0 to 1.0:0.

3.

6. 2. The photocurable resin composition according to claim 1, further comprising component (D), wherein the content of component (D) is 1 to 100 parts by mass per 100 parts by mass of component (A).

7. The photocurable resin composition according to claim 1, further comprising at least one member selected from the group consisting of a curing accelerator and carbon black.

8. The photocurable resin composition according to any one of claims 1 to 7, which is used to form a balance weight for a rotating body.

9. A method for manufacturing a rotating body including a balance weight, comprising: A step of applying the photocurable resin composition according to any one of claims 1 to 7 to a rotating body; The manufacturing method includes a step of irradiating the photocurable resin composition with light having a wavelength in the range of 300 to 600 nm to cure the composition, and forming a balance weight, which is a cured product of the photocurable resin composition, on a rotating body.

Images