Resin composition

Abstract

Disclosed is a resin composition which can obtain a cured product having excellent reflectance after a heat resistance test and excellent flexibility, a resin sheet containing the resin composition, a reflective sheet, and a printed wiring board. The resin composition contains (A) an epoxy resin in a liquid or semi-solid state at 25°C, (B) a phenoxy resin containing a fluorine atom, (C) a white inorganic oxide, and (D) a curing accelerator.

Description

Technical Field

[0001] This invention relates to resin compositions. It also relates to resin sheets, reflective sheets, and printed wiring boards obtained using these resin compositions. Background Technology

[0002] For printed wiring boards, the use of low-power light-emitting diodes (LEDs) for backlighting of LCD displays in mobile terminals, computers, televisions, etc., and light sources for lighting fixtures is increasing.

[0003] To improve the extraction efficiency of light emitted by the light source, a reflective sheet for reflecting light is formed on the outermost layer of such a printed wiring board.

[0004] The reflective sheet is required to have a high light reflectivity. As a material for the reflective sheet, for example, Patent Document 1 discloses a resin composition containing rutile titanium dioxide produced by chlorination and a curable resin. The rutile titanium dioxide is incorporated in a ratio of 30 to 600 parts by mass relative to 100 parts by mass of the curable resin, and the resin does not contain an active energy ray curable resin.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2017-220681. Summary of the Invention

[0008] The technical problem that the invention aims to solve

[0009] However, the reflective sheet formed from the resin composition described in Patent Document 1 (Japanese Patent Application Publication No. 2017-220681) deteriorates over time due to heat from the light source, resulting in poor reflectivity. Furthermore, the reflective sheet requires flexibility to accommodate various shapes of the light source.

[0010] The present invention addresses the aforementioned issues and aims to provide a resin composition that yields a cured product with excellent reflectivity after heat resistance testing and excellent flexibility, a resin sheet comprising the resin composition, a reflective sheet, and a printed wiring board.

[0011] Technical solutions adopted to solve technical problems

[0012] In order to solve the above-mentioned problems, the inventors conducted serious research and found that by making the resin composition contain (A) an epoxy resin that is liquid or semi-solid at 25°C, (B) a phenoxy resin containing fluorine atoms, (C) a white inorganic oxide, and (D) a curing accelerator, a cured product with excellent reflectivity after heat resistance test and excellent flexibility can be obtained, thus completing the present invention.

[0013] That is, the present invention includes the following:

[0014] [1] A resin composition comprising:

[0015] (A) Epoxy resin that is liquid or semi-solid at 25°C

[0016] (B) Phenoxy resins containing fluorine atoms,

[0017] (C) White inorganic oxides, and

[0018] (D) Curing accelerator;

[0019] [2] The resin composition according to [1], wherein component (D) includes a phosphorus curing accelerator;

[0020] [3] The resin composition according to [2], wherein the phosphorus curing accelerator comprises one or more selected from phosphonium salt and phosphine;

[0021] [4] The resin composition according to any one of [1] to [3], wherein when the solid content in the resin composition is set to 100% by mass, the content of component (C) is 60% by mass or more;

[0022] [5] The resin composition according to any one of [1] to [4], wherein component (C) is selected from alumina, titanium dioxide, zirconium oxide, magnesium oxide and barium titanate;

[0023] [6] The resin composition according to any one of [1] to [5] further contains (E) an antioxidant;

[0024] [7] The resin composition according to any one of [1] to [6] further contains (F) an ultraviolet absorber;

[0025] [8] The resin composition according to any one of [1] to [7] further contains (H) silica;

[0026] [9] The resin composition according to any one of [1] to [8] is used for light reflection;

[0027]

[10] A resin sheet comprising: a support body, and a resin composition layer comprising any one of the resin compositions described in [1] to [9] disposed on the support body;

[0028]

[11] A reflective sheet comprising a cured product of the resin composition described in any one of [1] to [9];

[0029]

[12] A printed wiring board comprising the reflective sheet described in

[11] .

[0030] The effects of the invention

[0031] If the present invention is used, it is possible to provide a resin composition that yields a cured product with excellent reflectivity after heat resistance testing and excellent flexibility, a resin sheet containing the resin composition, a reflective sheet, and a printed wiring board. Attached Figure Description

[0032] Figure 1 This is a schematic side view of an example of two test tubes used to determine the liquid, semi-solid, and solid states of epoxy resin.

[0033] Figure 2 This is a schematic cross-sectional view showing an example of a printed wiring board. Detailed Implementation

[0034] The present invention will now be described in detail with reference to its preferred embodiments. However, the present invention is not limited to the embodiments and examples described below, and can be implemented in any way without departing from the scope of the claims and their equivalents.

[0035] [Resin Composition]

[0036] The resin composition of the present invention contains (A) an epoxy resin that is liquid or semi-solid at 25°C, (B) a fluorine-containing phenoxy resin, (C) a white inorganic oxide, and (D) a curing accelerator. In the present invention, by including components (A) to (D), a resin composition with excellent reflectivity and flexibility after heat resistance testing can be obtained. Furthermore, a cured product with excellent reflectivity is generally obtained.

[0037] Regarding the resin composition, it may be combined with components (A) to (D) to further include any other components. Examples of such optional components include (E) antioxidants, (F) ultraviolet absorbers, (G) solid epoxy resins, (H) silica, and (I) other additives. The components contained in the resin composition will be described in detail below.

[0038] <(A) Epoxy resin that is liquid or semi-solid at 25°C>

[0039] The resin composition contains, as component (A), an epoxy resin that is liquid or semi-solid at 25°C. By including component (A) in the resin composition, the melt viscosity can be reduced and the flexibility improved. Component (A) can be used alone or in combination of two or more.

[0040] Here, the determination of liquid, semi-solid, and solid states is conducted according to Appendix 2, "Methods for Confirmation of Liquid State," of the Japanese Ministry Ordinance on Testing and Properties of Hazardous Materials (Ordinance No. 1 of the Japanese Ministry of Housing and Urban-Rural Development, 1989). The specific determination method is as follows.

[0041] (1) Apparatus

[0042] Constant temperature water tank:

[0043] A constant temperature water bath with a depth of 150 mm or more is used, equipped with a stirrer, heater, thermometer, automatic temperature controller (a controller capable of temperature control in ±0.1°C). It should be noted that in determining the epoxy resin used in the following examples, a combination of a low-temperature constant temperature water bath (model BU300) and an immersion thermostat ThermoMate (model BF500) manufactured by Yamato Scientific Co., Ltd. of Japan was used. Approximately 22 liters of tap water were added to the low-temperature constant temperature water bath (model BU300), the power supply to the ThermoMate (model BF500) installed therein was connected, the set temperature (20°C or 60°C) was set, and the water temperature was finely adjusted using the ThermoMate (model BF500) to ±0.1°C of the set temperature. However, any device capable of the same adjustment can be used.

[0044] test tube:

[0045] As a test tube, such as Figure 1As shown, a liquid state determination test tube 10a and a temperature measurement test tube 10b are used. The liquid state determination test tube 10a is a flat-bottomed cylindrical transparent glass test tube with an inner diameter of 30 mm and a height of 120 mm. Markings 11A and 12B are placed at heights of 55 mm and 85 mm from the bottom of the tube, respectively. The mouth of the test tube is sealed with a rubber stopper 13a. The temperature measurement test tube 10b is a test tube of the same size as the liquid state determination test tube 10a and is marked with the same markings. The mouth of the test tube is sealed with a rubber stopper 13b, which has a hole in the center for inserting and supporting a thermometer. A thermometer 14 is inserted into the rubber stopper 13b. Hereinafter, the marking at a height of 55 mm from the bottom of the tube will be referred to as "line A", and the marking at a height of 85 mm from the bottom of the tube will be referred to as "line B". As thermometer 14, a thermometer for determining the freezing point (SOP-58 scale range 0 to 100°C) as specified in JISB7410 (1982) "Glass thermometers for petroleum testing" is used, but any thermometer capable of measuring the temperature range of 0 to 100°C is acceptable.

[0046] (2) Experimental Implementation Steps

[0047] Samples that had been placed at 25°C and atmospheric pressure for more than 24 hours were separately loaded into... Figure 1 (a) shows the test tube 10a for determining the liquid state and Figure 1 (b) The temperature measurement test tube 10b is filled up to line 11A. Both test tubes 10a and 10b are placed upright in a low-temperature constant-temperature water bath with line 12B below the water surface. For the thermometer, its lower end is 30 mm below line 11A. After the sample temperature reaches the set temperature ±0.1℃, this state is maintained for 10 minutes. After 10 minutes, the liquid state determination test tube 10a is removed from the low-temperature constant-temperature water bath and immediately laid horizontally on a level test platform. A stopwatch is used to measure and record the time it takes for the front of the liquid surface in the test tube to move from line 11A to line 12B.

[0048] Similarly, for samples placed at atmospheric pressure at a temperature of 60±5℃ for more than 24 hours, the same test was conducted as for samples placed at atmospheric pressure at a temperature of 25℃ for more than 24 hours, and the time it took for the front of the liquid surface in the test tube to move from line 11A to line 12B was measured and recorded using a stopwatch.

[0049] Samples measured at 25°C for less than 90 seconds are considered liquid at 25°C. Samples measured at 25°C for more than 90 seconds but at 60°C for less than 90 seconds are considered semi-solid at 25°C. Samples measured at 60°C for more than 90 seconds are considered solid at 25°C.

[0050] The epoxy resin that is liquid or semi-solid at 25°C is preferably an epoxy resin having two or more epoxy groups per molecule. Furthermore, the epoxy resin preferably has an aromatic structure; when using two or more epoxy resins, it is even more preferable that at least one has an aromatic structure. An aromatic structure refers to a chemical structure generally defined as aromatic, including polycyclic aromatics and aromatic heterocycles. The proportion of epoxy resin having two or more epoxy groups per molecule is preferably 50% by mass or more, more preferably 60% by mass or more, and particularly preferably 70% by mass or more, relative to 100% by mass of the non-volatile component of the epoxy resin.

[0051] As for epoxy resins that are liquid or semi-solid at 25°C, aromatic epoxy resins such as glycirol type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AF type epoxy resin, naphthalene type epoxy resin, glycidyl ester type epoxy resin, glycidylamine type epoxy resin, and phenolic varnish type epoxy resin are preferred; non-aromatic epoxy resins such as alicyclic epoxy resin with ester skeleton, cyclohexanediol type epoxy resin, and epoxy resin with butadiene structure are preferred, and aromatic epoxy resins, bisphenol A type epoxy resin, and bisphenol F type epoxy resin are even more preferred. Specific examples of liquid and semi-solid epoxy resins include DIC Corporation's "HP4032", "HP4032D", and "HP4032SS" (naphthalene-type epoxy resin); Mitsubishi Chemical Corporation's "HP820" (aromatic epoxy resin); Mitsubishi Chemical Corporation's "828US", "jER828EL" (bisphenol A type epoxy resin), "jER807" (bisphenol F type epoxy resin), and "jER152" (phenolic varnish type epoxy resin); and Mitsubishi Chemical Corporation's "630" and "630LSD" (condensed epoxy resin). Glyceryl amine type epoxy resin), "ED-523T" (epoxypropoxy type epoxy resin (ADEKAGLYCIROL)) manufactured by ADEKA Co., Ltd., "EP-3980S" (glyceryl amine type epoxy resin), "EP-4088S" (dicyclopentadiene type epoxy resin) manufactured by ADEKA Co., Ltd., "ZX1059" (a mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin) manufactured by Nippon Steel Chemical Materials Co., Ltd., "EX-721" (glyceryl ester type epoxy resin) manufactured by Nagase ChemteX Co., Ltd., and "CELLOXIDE" manufactured by Daicel Co., Ltd. 2021P (an alicyclic epoxy resin with an ester backbone), PB-3600 (an epoxy resin with a butadiene structure), ZX1658 and ZX1658GS (liquid 1,4-glycidylcyclohexane) manufactured by Nippon Steel Chemical Materials Co., Ltd., and ELM-100 manufactured by Sumitomo Chemical Co., Ltd., etc. These can be used individually or in combination.

[0052] The epoxy equivalent of epoxy resins that are liquid or semi-solid at 25°C is preferably 50 g / eq. to 5000 g / eq., more preferably 50 g / eq. to 3000 g / eq., further preferably 80 g / eq. to 2000 g / eq., and even more preferably 110 g / eq. to 1000 g / eq. By ensuring this range, the crosslinking density of the cured product becomes sufficient, resulting in a cured product layer with low surface roughness. It should be noted that the epoxy equivalent can be determined according to JIS K 7236 and is the mass of resin containing 1 equivalent of epoxy groups.

[0053] The weight-average molecular weight of epoxy resins that are liquid or semi-solid at 25°C is preferably 100–5000, more preferably 250–3000, and even more preferably 400–1500. Here, the weight-average molecular weight of the epoxy resin is the weight-average molecular weight converted from that of polystyrene as determined by gel permeation chromatography (GPC).

[0054] Regarding the content of component (A), from the viewpoint of reducing the minimum melt viscosity and improving embeddability, when the non-volatile component in the resin composition is set to 100% by mass, it is preferably 1% by mass or more, more preferably 3% by mass or more, further preferably 5% by mass or more, preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less. It should be noted that, unless otherwise specified, the content of each component in the resin composition in this invention refers to the value when the non-volatile component in the resin composition is set to 100% by mass.

[0055] <(B) Phenoxy resins containing fluorine atoms>

[0056] For the resin composition, component (B) contains a phenoxy resin with fluorine atoms. The inventors conducted thorough research and found that by including component (B), the fluorine atoms in component (B) can improve the reflectivity and heat resistance of the cured resin composition, thus enabling the acquisition of a cured product with improved reflectivity and reflectivity after heat resistance testing. Component (B) can be used alone or in combination of two or more.

[0057] (B) The weight-average molecular weight of polystyrene converted from fluorine-containing phenoxy resin is preferably in the range of 8,000 to 70,000, more preferably in the range of 10,000 to 60,000, and even more preferably in the range of 20,000 to 60,000. (B) The weight-average molecular weight of polystyrene converted from fluorine-containing phenoxy resin is determined by gel permeation chromatography (GPC). Specifically, regarding the weight-average molecular weight of polystyrene converted from fluorine-containing phenoxy resin in (B), an LC-9A / RID-6A manufactured by Shimadzu Corporation can be used as the measuring apparatus, a Shodex K-800P / K-804L / K-804L manufactured by Showa Denko Corporation can be used as the column, chloroform or the like can be used as the mobile phase, the column temperature can be set to 40°C, and the molecular weight can be calculated using a calibration curve of standard polystyrene.

[0058] As (B) fluorine-containing phenoxy resins, examples include phenoxy resins containing fluorine atoms that have one or more skeletons selected from bisphenol A skeleton, bisphenol F skeleton, bisphenol AF skeleton, bisphenol S skeleton, bisphenol acetylbenzene skeleton, phenolic varnish skeleton, biphenyl skeleton, fluorene skeleton, dicyclopentadiene skeleton, norbornene skeleton, naphthalene skeleton, anthracene skeleton, adamantane skeleton, terpene skeleton and trimethylcyclohexane skeleton.

[0059] As the phenoxy resin containing fluorine atoms (B), a phenoxy resin having one or more fluorine atoms can be used. From the viewpoint of obtaining the desired effects of the present invention, it is preferable that the backbone constituting the phenoxy resin contains fluorine atoms. The backbone constituting the phenoxy resin refers to the repeating units constituting component (B).

[0060] Regarding the number of fluorine atoms in the skeleton constituting the phenoxy resin, on average, each fluorine atom constituting the skeleton of the phenoxy resin preferably has more than one fluorine atom, more preferably more than two, and even more preferably more than three or five. There is no particular upper limit, and it can be less than ten, etc.

[0061] Examples of phenoxy resins containing fluorine atoms include "YL7876B40", "YL7957B40", "YL7383BH30", and "YL7384BH30" manufactured by Mitsubishi Chemical Corporation.

[0062] From the viewpoint of obtaining a cured product with improved reflectivity and heat resistance after a heat resistance test, when the non-volatile component in the resin composition is set to 100% by mass, the content of component (B) is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more. The upper limit is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less.

[0063] When the content of component (A) in the resin composition is set to 100% by mass, and the content of component (B) in the resin composition is set to 100% by mass, the ratio of A1 / B1 is preferably 0.1 or more, more preferably 0.3 or more, even more preferably 0.5 or more, preferably 5 or less, more preferably 3 or less, and even more preferably 2 or less. By adjusting A1 / B1 to the aforementioned range, the flexibility can be further improved.

[0064] <(C) White Inorganic Oxide>

[0065] The resin composition contains (C) white inorganic oxide as component (C). However, silica is not included in the (C) white inorganic oxide. By including the (C) white inorganic oxide in the resin composition, a cured product with improved reflectivity and reflectivity after heat resistance testing can be obtained. Here, (C) white inorganic oxide refers to an inorganic oxide with a reflectivity of 90% or more for light at 500 nm.

[0066] Examples of materials that are (C) white inorganic oxides include alumina, aluminosilicates, cordierite, silicon oxides, barium sulfate, barium carbonate, talc, clay, mica powder, zinc oxide, hydrotalcite, boehmite, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, magnesium oxide, boron nitride, aluminum nitride, manganese nitride, aluminum borate, strontium carbonate, strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, titanium oxide, zirconium oxide, barium titanate, barium zirconate titanate, barium zirconate, calcium zirconate, zirconium phosphate, and zirconium tungstate phosphate. Among these, alumina, titanium oxide, zirconium oxide, magnesium oxide, and barium titanate are preferred, with titanium oxide being particularly preferred. (C) White inorganic oxides may be used alone or in combination of two or more.

[0067] (C) The titanium oxide in the composition can be any of the rutile, anatase, and brookite types. Among these, rutile is preferred from the viewpoint of improving reflectivity and reflectivity after heat resistance testing. The titanium oxide can be material obtained by methods such as the sulfuric acid process or the chlorination process.

[0068] Commercially available products as component (C) include, for example, PX3788 manufactured by Sakai Chemical Co., Ltd.; TIPAQUE CR-50, TIPAQUE CR-57, TIPAQUE CR-80, TIPAQUE CR-90, TIPAQUE CR-93, TIPAQUE CR-95, TIPAQUE CR-97, TIPAQUE CR-60, TIPAQUE CR-63, TIPAQUE CR-67, TIPAQUE CR-58, TIPAQUE CR-85, and TIPAQUE UT771 manufactured by Ishihara Sangyo Co., Ltd.; and Ti-Pure R-100, Ti-Pure R-101, Ti-Pure R-102, Ti-Pure R-103, Ti-Pure R-104, Ti-Pure R-105, Ti-Pure R-108, Ti-Pure R-900, and Ti-Pure R-101 manufactured by DuPont. R-902, Ti-Pure R-960, Ti-Pure R-706, Ti-Pure R-931; "AHP300" manufactured by Nippon Light Metal Co., Ltd.; "ALUNABEADS (registered trademark) CB" (e.g., "CB-P05", "CB-A30S") manufactured by Showa Denko Co., Ltd., etc.

[0069] The specific surface area of ​​component (C) is preferably 0.5 m². 2 / g or higher, preferably 1m 2 / g or higher, especially 2m 2 / g or above. There is no particular limit to the upper limit, but 80m is preferred. 2 / g or less, 70m 2 / g or less or 60m 2 / g or less. Regarding the specific surface area, it can be obtained by using a specific surface area measuring device (Macsorb HM-1210 manufactured by Mounttech Co., Ltd.) to adsorb nitrogen onto the sample surface and then calculating the specific surface area using the BET multi-point method.

[0070] From the viewpoint of significantly achieving the desired effect of the present invention, the average particle size of component (C) is preferably 0.01 μm or more, more preferably 0.05 μm or more, even more preferably 0.1 μm or more, preferably 5 μm or less, more preferably 2 μm or less, and even more preferably 1 μm or less.

[0071] The average particle size of component (C) can be determined using laser diffraction scattering based on the Mie scattering theory. Specifically, a particle size distribution of component (C) can be prepared on a volume basis using a laser diffraction scattering particle size distribution measuring device, and the median particle size can be used as the average particle size for measurement. The sample used for measurement can be prepared by weighing 100 mg of component (C) and 10 g of methyl ethyl ketone into a vial and dispersing it ultrasonically for 10 minutes. For the sample, a laser diffraction particle size distribution measuring device can be used, employing blue and red light source wavelengths, to measure the volume-based particle size distribution of component (C) using a flow cell method. The average particle size is calculated based on the obtained particle size distribution as the median particle size. Examples of laser diffraction particle size distribution measuring devices include the "LA-960" manufactured by Horiba Manufacturing Co., Ltd.

[0072] From the viewpoint of improving moisture resistance and dispersibility, component (C) is preferably surface-treated with a surface treatment agent. Examples of surface treatment agents include vinyl silane coupling agents, (meth)acrylic acid coupling agents, fluorinated silane coupling agents, aminosilane coupling agents, epoxy silane coupling agents, mercaptosilane coupling agents, silane coupling agents, alkoxysilanes, organosilazane compounds, and titanate coupling agents. Among these, aminosilane coupling agents are preferred from the viewpoint of significantly achieving the effects of the present invention. Furthermore, a single surface treatment agent may be used, or two or more may be used in any combination.

[0073] Commercially available surface treatment agents include, for example, "KBM1003" (vinyltriethoxysilane) manufactured by Shin-Etsu Chemical Industry Co., Ltd., "KBM503" (3-methacryloyloxypropyltriethoxysilane) manufactured by Shin-Etsu Chemical Industry Co., Ltd., "KBM403" (3-epoxypropoxypropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Industry Co., Ltd., "KBM803" (3-mercaptopropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Industry Co., Ltd., and "KBE903" (3- Products manufactured by Shin-Etsu Chemical Co., Ltd. include: aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane (KBM573), SZ-31 (hexamethyldisilazane) (SZ-31), phenyltrimethoxysilane (KBM103), long-chain epoxy silane coupling agent (KBM-4803), and 3,3,3-trifluoropropyltrimethoxysilane (KBM-7103).

[0074] From the viewpoint of improving the dispersibility of component (C), the degree of surface treatment by the surface treatment agent is preferably within the specified range. Specifically, it is preferable that 100 parts by mass of component (C) has been surface treated with 0.2 to 5 parts by mass of the surface treatment agent, more preferably with 0.2 to 3 parts by mass of the surface treatment agent, and even more preferably with 0.3 to 2 parts by mass of the surface treatment agent.

[0075] The degree of surface treatment by the surface treatment agent can be evaluated by the carbon content per unit surface area of ​​component (C). From the viewpoint of improving the dispersibility of component (C), the carbon content per unit surface area of ​​component (C) is preferably 0.02 mg / m². 2 The above is preferred, ideally 0.1 mg / m². 2 The above, especially 0.2 mg / m², is preferred. 2 That's all. On the other hand, from the viewpoint of suppressing the increase in melt viscosity of the resin varnish and melt viscosity in sheet form, 1 mg / m³ is preferable. 2 The following is preferable: 0.8 mg / m² 2 The following is even better: 0.5 mg / m² 2 the following.

[0076] The carbon content per unit surface area of ​​component (C) can be determined after cleaning the surface-treated component (C) with a solvent (e.g., methyl ethyl ketone (MEK)). Specifically, sufficient MEK is added to the surface-treated component (C) as a solvent, and the mixture is ultrasonically cleaned at 25°C for 5 minutes. After removing the supernatant and drying the solid component, the carbon content per unit surface area of ​​component (C) can be determined using a carbon analyzer. A carbon analyzer such as the "EMIA-320V" manufactured by Horiba Corporation can be used.

[0077] From the viewpoint of obtaining a cured product with improved reflectivity and heat resistance after a heat resistance test, when the non-volatile component in the resin composition is set to 100% by mass, the content of component (C) is preferably 60% by mass or more, more preferably 65% ​​by mass or more, even more preferably 70% by mass or more, 75% by mass or more, preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 80% by mass or less.

[0078] When the content of component (C) in the resin composition is set to C1 when the non-volatile component is set to 100% by mass, the B1 / C1 ratio is preferably 0.01 or more, more preferably 0.03 or more, even more preferably 0.05 or more, preferably 1 or less, more preferably 0.5 or less, and even more preferably 0.3 or less. The effects of the present invention can be further improved by adjusting the B1 / C1 to the aforementioned range.

[0079] Furthermore, (A1+B1) / C1 is preferably 0.01 or more, more preferably 0.05 or more, even more preferably 0.1 or more, preferably 3 or less, more preferably 1 or less, and even more preferably 0.5 or less. The effectiveness of the present invention can be further improved by adjusting (A1+B1) / C1 to the aforementioned range.

[0080] <(D) Curing Accelerator>

[0081] For the resin composition, component (D) contains a curing accelerator (D). The curing accelerator (D) typically functions to react with component (A) to cure the resin composition. Examples of curing accelerators (D) include phosphorus-based curing accelerators, imidazole-based curing accelerators, amine-based curing accelerators, guanidine-based curing accelerators, and metal-based curing accelerators. From the viewpoint of achieving higher reflectivity, phosphorus-based curing accelerators and imidazole-based curing accelerators are preferred, and phosphorus-based curing accelerators are even more preferred. A single curing accelerator (D) may be used, or two or more may be used in combination.

[0082] From the viewpoint of achieving higher reflectivity, it is preferable for phosphorus-based curing accelerators to include one or more selected from phosphonium salts and phosphine.

[0083] Examples of phosphonium salts include phosphonium borate compounds, tetraphenylphosphonium tetraphenylborate, n-butylphosphonium tetraphenylborate, tetrabutylphosphonium decanoate, (4-methylphenyl)triphenylphosphonium thiocyanate, tetraphenylphosphonium thiocyanate, butyltriphenylphosphonium thiocyanate, etc.

[0084] Examples of phosphine species include triphenylphosphine, tricyclohexylphosphine, tributylphosphine, and methyldiphenylphosphine.

[0085] As a phosphorus-based curing accelerator, commercially available products can be used, such as "TBP-DA" manufactured by Hokuko Co., Ltd.

[0086] Examples of imidazole curing accelerators include 2-methylimidazolium, 2-undecylimidazolium, 2-heptadecylimidazolium, 1,2-dimethylimidazolium, 2-ethyl-4-methylimidazolium, 1,2-dimethylimidazolium, 2-ethyl-4-methylimidazolium, 2-phenylimidazolium, 2-phenyl-4-methylimidazolium, 1-benzyl-2-methylimidazolium, 1-benzyl-2-phenylimidazolium, 1-cyanoethyl-2-methylimidazolium, 1-cyanoethyl-2-undecylimidazolium, 1-cyanoethyl-2-ethyl-4-methylimidazolium, 1-cyanoethyl-2-phenylimidazolium, 1-cyanoethyl-2-undecylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-triazine, 2,4-di... Amino-6-[2'-undecylimidazolyl-(1')]-ethyl-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-triazine isocyanuric acid adduct, 2-phenylimidazolyl isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazolium, 2-phenyl-4-methyl-5-hydroxymethylimidazolium, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 1-dodecyl-2-methyl-3-benzylimidazolium chloride, 2-methylimidazoline, 2-phenylimidazoline and other imidazole compounds, and adducts of imidazole compounds with epoxy resins, preferably 2-ethyl-4-methylimidazolium and 1-benzyl-2-phenylimidazolium.

[0087] As an imidazole curing accelerator, commercially available products can be used, such as "P200-H50" manufactured by Mitsubishi Chemical Corporation and "1B2PZ-10M" manufactured by Shikoku Chemical Industry Co., Ltd.

[0088] Examples of amine curing accelerators include trialkylamines such as triethylamine and tributylamine, 4-dimethylaminopyridine, benzyl dimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, and 1,8-diazabicyclo[5.4.0]undecene, with 4-dimethylaminopyridine and 1,8-diazabicyclo[5.4.0]undecene being preferred.

[0089] Examples of guanidine curing accelerators include dicyandiamide, 1-methylguanidine, 1-ethylguanidine, 1-cyclohexylguanidine, 1-phenylguanidine, 1-(o-tolyl)guanidine, dimethylguanidine, diphenylguanidine, trimethylguanidine, tetramethylguanidine, pentamethylguanidine, 1,5,7-triazabicyclo[4.4.0]decene-5, 7-methyl-1,5,7-triazabicyclo[4.4.0]decene-5, 1-methylbiguanidine, 1-ethylbiguanidine, 1-n-butylbiguanidine, 1-n-octadecylbiguanidine, 1,1-dimethylbiguanidine, 1,1-diethylbiguanidine, 1-cyclohexylbiguanidine, 1-allylbiguanidine, 1-phenylbiguanidine, and 1-(o-tolyl)biguanidine, with dicyandiamide and 1,5,7-triazabicyclo[4.4.0]decene-5 being preferred.

[0090] Examples of organometallic curing accelerators include organometallic complexes or organometallic salts of metals such as cobalt, copper, zinc, iron, nickel, manganese, and tin. Specific examples of organometallic complexes include organocobalt complexes such as cobalt(II) and cobalt(III) acetylacetone, organocopper complexes such as copper(II) acetylacetone, organozinc complexes such as zinc(II) acetylacetone, organoiron complexes such as iron(III) acetylacetone, organonickel complexes such as nickel(II) acetylacetone, and organomanganese complexes such as manganese(II) acetylacetone. Examples of organometallic salts include zinc octoate, tin octoate, zinc naphthenate, cobalt naphthenate, tin stearate, and zinc stearate.

[0091] From the viewpoint of achieving higher reflectivity, when the non-volatile component in the resin composition is set to 100% by mass, the content of (D) curing accelerator is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, particularly preferably 0.1% by mass or more, preferably 3% by mass or less, more preferably 1% by mass or less, and particularly preferably 0.5% by mass or less.

[0092] <(E) Antioxidants>

[0093] In addition to the components described above, the resin composition may further include (E) an antioxidant as an optional component.

[0094] Examples of (E) antioxidants include hindered phenolic antioxidants, phosphorus antioxidants, and sulfur antioxidants. From the perspective of further improving reflectivity after heat treatment, hindered phenolic antioxidants are preferred. (E) antioxidants can be used alone or in combination of two or more.

[0095] Specific examples of (E) antioxidants include butylated hydroxytoluene (BHT), pentaerythritol tetra(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (“IRGANOX 1010” manufactured by Ciba Japan (BASF) Co., Ltd.), 2,2-thionyl ethylene glycol bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (“IRGANOX 1035” manufactured by Ciba Japan Co., Ltd.), 1,3,5-tris[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione (“IRGANOX 3114” manufactured by Ciba Japan Co., Ltd.), etc.

[0096] From the viewpoint of further improving the reflectivity after heat treatment, when the content of the (E) antioxidant is set to 100% by mass, it is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, even more preferably 0.03% by mass or more, preferably 3% by mass or less, more preferably 2% by mass or less, and even more preferably 1% by mass or less.

[0097] <(F) Ultraviolet Absorber>

[0098] From the viewpoint of further improving the photostability of the resin composition, the resin composition may further contain an (F) ultraviolet absorber as an optional component.

[0099] Examples of (F) ultraviolet absorbers include benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, and salicylic acid-based ultraviolet absorbers. An (F) ultraviolet absorber can be used alone or in combination with two or more other absorbers.

[0100] Examples of benzophenone-based ultraviolet absorbers include 2-hydroxy-4-octyloxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid, 2-hydroxy-4-n-octylbenzophenone, 2-hydroxy-4-n-dodecyloxybenzophenone, bis(5-benzoyl-4-hydroxy-2-methoxyphenyl)methane, 2,2'-dihydroxy-4-methoxybenzophenone, and 2,2'-dihydroxy-4,4'-dimethoxybenzophenone.

[0101] Examples of benzotriazole-based ultraviolet absorbers include 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-[2'-hydroxy-3',5'-bis(α,α-dimethylbenzyl)phenyl]-benzotriazole, 2-(2'-hydroxy-3',5-di-tert-butylphenyl)-benzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-tert-pentyl)benzotriazole, 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, and 2,2-methylenebis[4-(1,1,3,3-tetramethylbutyl)-6-(2N-benzotriazole-2-yl)phenol].

[0102] Examples of salicylic acid-based ultraviolet absorbers include phenyl salicylate, 4-tert-butyl phenyl salicylate, phenyl 2-hydroxybenzoate, 2,4-di-tert-butyl-4-hydroxybenzoate, hexadecyl 3,5-di-tert-butyl-4-hydroxybenzoate, ethylene cyano-3,3'-diphenylacrylate, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, and 2-hydroxy-4-octoxybenzophenone.

[0103] (F) Commercially available UV absorbers may be used. Examples of commercially available UV absorbers for (F) include BASF's "Chimassorb 81 FL", ADEKA Corporation's LA-52 (tetra(1,2,2,6,6-pentamethyl-4-piperidinyl) ester), LA-57 (tetra(2,2,6,6-tetramethyl-4-piperidinyl) ester), LA-63P (a mixture of esters of 1,2,3,4-butanetetracarboxylic acid, 1,2,2,6,6-pentamethyl-4-piperidinol, and 3,9-bis(2-hydroxy-1,1-dimethylethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane), and LA-72 (bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, etc.

[0104] From the viewpoint of further improving the photostability of the resin composition, when the content of the (F) ultraviolet absorber is set to 100% by mass, it is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, even more preferably 0.03% by mass or more, preferably 1% by mass or less, more preferably 0.5% by mass or less, and even more preferably 0.1% by mass or less.

[0105] <(G) Epoxy resin that is solid at 25°C>

[0106] For the resin composition, it may further contain (G) an epoxy resin that is solid at 25°C (hereinafter also referred to as "solid epoxy resin") as an optional component.

[0107] Solid epoxy resins preferably include epoxy resins having two or more epoxy groups per molecule. Furthermore, solid epoxy resins preferably have an aromatic structure; when using two or more epoxy resins, it is more preferable that at least one has an aromatic structure. The proportion of epoxy resin having two or more epoxy groups per molecule relative to 100% by mass of the non-volatile component of the epoxy resin is preferably 50% by mass or more, more preferably 60% by mass or more, and particularly preferably 70% by mass or more.

[0108] As solid epoxy resins, fluorinated epoxy resins such as bisphenol AF type epoxy resin and perfluoroalkyl type epoxy resin, naphthyl tetrafunctional epoxy resin, cresol phenolic varnish type epoxy resin, dicyclopentadiene type epoxy resin, triphenol type epoxy resin, naphthol type epoxy resin, biphenyl type epoxy resin, naphthylene ether type epoxy resin, anthracene type epoxy resin, bisphenol A type epoxy resin, and tetraphenylethane type epoxy resin are preferred, and fluorinated epoxy resins are even more preferred. Specific examples of solid epoxy resins include: DIC Corporation's "HP4032H" (naphthalene-type epoxy resin), "HP-4700", "HP-4710" (naphthalene-type tetrafunctional epoxy resin), "N-690" (cresol phenolic varnish type epoxy resin), "N-695" (cresol phenolic varnish type epoxy resin), "HP-7200" (dicyclopentadiene type epoxy resin), "HP-7200HH", "HP-7200H", "EXA-7311", "EXA-7311-G3", "EXA-7311-G4", "EXA-7311-G4S", and "HP6000" (naphthyl ether type epoxy resin); and Nippon Kayaku Co., Ltd.'s "EPPN-502H" (triphenol type epoxy resin), "NC7000L" (naphthyl phenolic varnish type epoxy resin), "NC3000H", and "NC3000". "NC3000L" and "NC3100" (biphenyl type epoxy resin); "ESN475V" (naphthalene type epoxy resin) and "ESN485" (naphthol phenolic varnish type epoxy resin) manufactured by Nippon Steel Chemical Materials Co., Ltd.; "YX4000H", "YX4000", "YL6121" (biphenyl type epoxy resin), "YX4000HK" (bixylenol type epoxy resin), and "YX88" manufactured by Mitsubishi Chemical Corporation. 00" (anthracene type epoxy resin), "PG-100" and "CG-500" manufactured by Osaka Gas Chemical Co., Ltd., "YL7760" (bisphenol AF type epoxy resin), "YL7800" (fluorene type epoxy resin), "jER1010" (solid bisphenol A type epoxy resin), "jER1031S" (tetraphenylethane type epoxy resin), "YL7760" (bisphenol AF type epoxy resin) manufactured by Mitsubishi Chemical Co., Ltd., etc.

[0109] The epoxy equivalent and weight-average molecular weight of the solid epoxy resin are the same as those of component (A).

[0110] From the viewpoint of significantly obtaining the effects of the present invention, when the content of the non-volatile component in the resin composition is set to 100% by mass, it is preferably 1% by mass or more, more preferably 2% by mass or more, particularly preferably 3% by mass or more, preferably 10% by mass or less, more preferably 8% by mass or less, and particularly preferably 5% by mass or less.

[0111] <(H)silicon dioxide>

[0112] The resin composition may further contain (H) silica as an optional component.

[0113] Examples of (H) silica include amorphous silica, fused silica, crystalline silica, synthetic silica, and hollow silica. Furthermore, spherical silica is preferred as (H) silica. The specific surface area and average particle size of the (H) silica are the same as those of (C). (H) silica can be used alone or in combination of two or more types.

[0114] Commercially available products of (H) silica include, for example, "UFP-30" manufactured by DENKA Corporation, "SP60-05" and "SP507-05" manufactured by Nippon Steel Chemical Materials Co., Ltd., "YC100C", "YA050C", "YA050C-MJE" and "YA010C" manufactured by Yatuma Corporation, "SILFIL NSS-3N", "SILFIL NSS-4N" and "SILFIL NSS-5N" manufactured by Tokuyama Corporation, and "SC2500SQ", "SO-C4", "SO-C2" and "SO-C1" manufactured by Yatuma Corporation.

[0115] From the viewpoint of improving moisture resistance and dispersibility, (H) silica is preferably surface-treated with a surface treatment agent. The surface treatment agent is the same as that in component (C).

[0116] From the viewpoint of achieving significant effects of the present invention, when the non-volatile component in the resin composition is set to 100% by mass, the content of (H) silica is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 25% by mass or more, preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less.

[0117] <(I) Other Additives>

[0118] In addition to the components described above, the resin composition may further include other additives as optional components. Examples of such additives include resin additives such as thickeners, defoamers, leveling agents, and adhesion promoters. These additives may be used alone or in combination of two or more. Those skilled in the art can appropriately determine the content of each additive.

[0119] The preparation method of the resin composition of the present invention is not particularly limited. Examples include adding solvents as needed for the compounding components, and mixing and dispersing by means of a rotary mixer or the like.

[0120] <Properties and Uses of Resin Compositions>

[0121] The resin composition of the present invention, containing components (A) to (D), yields a cured product with excellent reflectivity and reflectivity after heat resistance testing. Therefore, the resin composition of the present invention is suitable for use as a resin composition for obtaining a cured product for light reflection (resin composition for light reflection). Specifically, it is suitable for use as a resin composition for forming a reflective sheet on the outermost layer of a printed wiring board. Furthermore, the resin composition of the present invention is also suitable for use as a resin composition for insulating a solder resist layer of a printed wiring board. Therefore, the resin composition of the present invention is suitable for use as a resin composition for forming a layer that serves as both a solder resist layer and a reflective sheet.

[0122] The resin composition of the present invention exhibits a low melt viscosity due to the inclusion of component (A). Preferably, the melt viscosity of the resin composition is less than 10,000 poise, more preferably less than 5,000 poise, and even more preferably less than 4,500 poise. The lower limit of the melt viscosity is 100 poise or more, preferably 500 poise or more, and more preferably 1,000 poise or more. Here, the term "melt viscosity" refers to the lowest melt viscosity in the range of 60°C to 200°C. The lowest melt viscosity can be measured using a dynamic viscoelasticity measuring device. The determination of the lowest melt viscosity can be performed according to the method described in the examples described later. By keeping the lowest melt viscosity of the resin composition within the aforementioned range, excellent flexibility is achieved.

[0123] The cured product obtained by curing the resin composition at 170°C for 60 minutes exhibits excellent reflectivity for light with a wavelength of 460 nm. Therefore, the cured product can reflect light with high reflectivity, for example, resulting in a reflective sheet with improved reflectivity for light with a wavelength of 460 nm. The reflectivity is preferably greater than 85%, more preferably greater than 90%, and even more preferably greater than 92%. The upper limit of reflectivity can be set to 100% or less, etc. The reflectivity can be measured according to the method described in the examples described later.

[0124] The cured product, which undergoes a heat resistance test by curing the resin composition at 170°C for 60 minutes and then at 125°C for 100 hours, reflects light with high reflectivity, exhibiting excellent reflectivity for light with a wavelength of 460 nm. Therefore, the cured product can provide a reflective sheet with improved reflectivity for light with a wavelength of 460 nm after the heat resistance test. The reflectivity after the heat resistance test is preferably greater than 80%, more preferably greater than 85%, and even more preferably greater than 88%. The upper limit of the reflectivity after the heat resistance test can be set to 100% or less. The reflectivity after the heat resistance test can be measured according to the method described in the examples below.

[0125] [Resin Sheets]

[0126] The resin sheet of the present invention includes a support and a resin composition layer formed of the resin composition of the present invention disposed on the support.

[0127] From the viewpoint of achieving thinner printed wiring boards and providing a cured product of the resin composition that exhibits excellent insulation even as a thin film, the thickness of the resin composition layer is preferably 200 μm or less, more preferably 100 μm or less, and even more preferably 80 μm or less. There is no particular limitation on the lower limit of the resin composition layer thickness; it is typically set to 5 μm or more, 10 μm or more, etc.

[0128] Examples of supports include films made of plastic materials, metal foils, and release paper, with films and metal foils made of plastic materials being preferred.

[0129] When using a film formed of a plastic material as a support, examples of plastic materials include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), acrylic polymers such as polycarbonate (PC) and polymethyl methacrylate (PMMA), cyclic polyolefins, triacetyl cellulose (TAC), polyether sulfide (PES), polyether ketone, and polyimide. Among these, polyethylene terephthalate and polyethylene naphthalate are preferred, and inexpensive polyethylene terephthalate is particularly preferred.

[0130] When using metal foil as a support, examples of metal foils include copper foil and aluminum foil, with copper foil being preferred. Copper foil can be used as the support, either as a single metal such as copper or as an alloy of copper with other metals (e.g., tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.).

[0131] For the support, matte finish, corona treatment, and antistatic treatment can be applied to the surface that bonds with the resin composition layer.

[0132] Furthermore, as a support, a support with a release layer can be used on the surface that bonds to the resin composition layer. As a release agent for the release layer of the support with a release layer, examples include one or more release agents selected from alkyd resins, polyolefin resins, polyurethane resins, and silicone resins. Commercially available products can be used as the support with the release layer, such as PET films having a release layer with an alkyd resin-based release agent as the main component, namely, "PET501010," "SK-1," "AL-5," and "AL-7" manufactured by Lintec Corporation, "LUMIRROR T60" manufactured by Toray Industries, Ltd., "Purex" manufactured by Teijin Corporation, and "Unipeel" manufactured by Unitech Co., Ltd.

[0133] The thickness of the support is not particularly limited, but it is preferably in the range of 5 μm to 75 μm, and more preferably in the range of 10 μm to 60 μm. It should be noted that when using a support with a release layer, it is preferable that the overall thickness of the support with the release layer is within the above range.

[0134] In one embodiment, the resin sheet may further comprise other layers as needed. Examples of these other layers include, for instance, a protective film disposed on the side of the resin composition layer that is not bonded to the support (i.e., the side opposite to the support), depending on the support being used. The thickness of the protective film is not particularly limited, but is, for example, 1 μm to 40 μm. By laminating the protective film, the adhesion of debris or damage to the surface of the resin composition layer can be suppressed.

[0135] Resin sheets can be manufactured, for example, by preparing a resin varnish obtained by dissolving a resin composition in an organic solvent, applying the resin varnish onto a support using a diecoater or similar machine, and then drying it to form a resin composition layer.

[0136] Examples of organic solvents include ketones such as acetone, methyl ethyl ketone (MEK), and cyclohexanone; acetates such as ethyl acetate, butyl acetate, acetic acid solvents, propylene glycol monomethyl ether acetate, and carbitol acetate; carbitols such as solvents and butyl carbitol; aromatics such as toluene and xylene; and amide solvents such as dimethylformamide, dimethylacetamide (DMAc), and N-methylpyrrolidone. Organic solvents can be used alone or in combination.

[0137] Drying can be carried out by known methods such as heating or hot air blowing. There are no particular limitations on drying conditions, but drying is carried out when the content of organic solvent in the resin composition layer is 10% by mass or less, preferably 5% by mass or less. Drying conditions also vary depending on the boiling point of the organic solvent in the resin varnish. For example, when using a resin varnish containing 30% to 60% by mass of organic solvent, the resin composition layer can be formed by drying at 50°C to 150°C for 3 to 10 minutes.

[0138] Resin sheets can be stored in rolls. If the resin sheet has a protective film, it can be used by peeling off the protective film.

[0139] The resin composition of the present invention used for the resin composition layer has a low melt viscosity, and therefore excellent flexibility. Consequently, the resin sheet exhibits excellent flexibility. Specifically, when the resin sheet is bent 180 degrees along an axis with a diameter of 1 mm with the support inside, cracking of the resin sheet is suppressed.

[0140] [cured material]

[0141] The cured product of the present invention is obtained by curing the resin composition of the present invention. The curing conditions of the resin composition may use the conditions of step (II) described later. In addition, preheating may be performed before curing the resin composition, and the heating, including preheating, may be performed multiple times.

[0142] [Reflective sheets, printed wiring boards]

[0143] The reflective sheet of the present invention comprises a cured product of the resin composition of the present invention. Furthermore, the printed wiring board of the present invention comprises the reflective sheet of the present invention. For example... Figure 2 As shown in one example, for the printed wiring board 1, a reflective sheet 3 is formed on the substrate 2, and a light source 4 such as a light-emitting diode (LED) is disposed on the surface 31 of the reflective sheet 3.

[0144] The reflective sheet contains a cured product of the resin composition of the present invention, and therefore can reflect light with high reflectivity. For example, the reflectivity of light with a wavelength of 460 nm is preferably more than 85%, more preferably more than 90%, and even more preferably more than 92%. The upper limit of reflectivity can be set to 100% or less. Furthermore, the reflective sheet contains a cured product of the resin composition of the present invention, and therefore can reflect light with high reflectivity even after heat resistance testing. For example, the reflectivity of light with a wavelength of 460 nm after heat resistance testing is preferably more than 80%, more preferably more than 85%, and even more preferably more than 88%. The upper limit of reflectivity after heat resistance testing can be set to 100% or less. The reflectivity and the reflectivity after heat resistance testing can be measured, for example, using a multichannel spectrometer (manufactured by Otsuka Electronics Co., Ltd., MCPD-7700).

[0145] The printed wiring board and reflective sheet of the present invention can be manufactured, for example, using the above-described resin sheet through a method comprising the following steps (I), (II) and (III):

[0146] (I) A process of laminating a resin composition layer of a resin sheet onto a substrate by bonding it to the substrate.

[0147] (II) The process of thermosetting the resin composition layer to form a reflective sheet;

[0148] (III) The process of placing the light source on the reflective sheet.

[0149] There are no restrictions on the substrate used in process (I). For example, a circuit board having an insulating layer, a conductor layer formed on the insulating layer, and a solder resist layer formed on the conductor layer can be used.

[0150] The lamination of the substrate and the resin sheet can be achieved, for example, by heating and pressing the resin sheet onto the substrate from the self-supporting side. Examples of components for heating and pressing the resin sheet onto the substrate (hereinafter also referred to as "heat-pressing components") include, for example, a heated metal plate (SUS end face) or a metal roller (SUS roller). It should be noted that it is preferable not to press the heat-pressing component directly onto the resin sheet, but rather to press it using an elastic material such as heat-resistant rubber, so that the resin sheet fully conforms to the surface irregularities of the substrate.

[0151] The lamination of the substrate and the resin sheet can be carried out by vacuum lamination. In vacuum lamination, the heat-pressing temperature is preferably in the range of 60℃ to 160℃, more preferably 80℃ to 140℃; the heat-pressing pressure is preferably in the range of 0.098MPa to 1.77MPa, more preferably 0.29MPa to 1.47MPa; and the heat-pressing time is preferably in the range of 20 seconds to 400 seconds, more preferably 30 seconds to 300 seconds. Lamination is preferably carried out under reduced pressure conditions below 26 hPa.

[0152] Lamination can be performed using commercially available vacuum laminators. Examples of commercially available vacuum laminators include the vacuum pressure laminator manufactured by Meiki Manufacturing Co., Ltd., the vacuum dressing machine manufactured by Nikko-Materials Co., Ltd., and the batch vacuum pressure laminator.

[0153] After lamination, the laminated resin sheets can be smoothed under normal pressure (atmospheric pressure), for example, by pressing the heated bonding member from the support side. The pressing conditions for smoothing can be the same as the heating and pressing conditions for lamination described above. Smoothing can be performed using a commercially available laminator. It should be noted that lamination and smoothing can be performed continuously using the aforementioned commercially available vacuum laminator.

[0154] The support can be removed between process (I) and process (II), or it can be removed after process (II).

[0155] In step (II), the resin composition layer is thermocured to form a reflective sheet. For example, the thermocuring conditions of the resin composition layer vary depending on the type of resin composition, etc. The curing temperature is preferably 120°C to 240°C, more preferably 130°C to 220°C, and even more preferably 150°C to 210°C. The curing time is preferably 5 minutes to 120 minutes, more preferably 10 minutes to 100 minutes, and even more preferably 15 minutes to 100 minutes.

[0156] The resin composition may be preheated at a temperature lower than the curing temperature before curing. For example, the resin composition may be preheated for 5 minutes or more (preferably 5 minutes to 150 minutes, more preferably 15 minutes to 120 minutes, and even more preferably 15 minutes to 100 minutes) at a temperature of 50°C or higher and lower than 120°C (preferably 60°C or higher and lower than 115°C, and more preferably 70°C or higher and lower than 110°C) before heat curing.

[0157] To improve the light extraction efficiency emitted by the light source, the light source side of the reflective sheet can have features other than those shown below. Figure 2 concave portions other than flat surfaces.

[0158] In step (III), a light source is positioned on the reflective sheet. For example, if the surface of the reflective sheet has a recess, the light source is positioned within the recess.

[0159] The light source can be electrically connected as needed, and then sealed to fix it in place.

[0160] [Example]

[0161] The present invention will now be described in more detail with reference to the embodiments, but the present invention is not limited to these embodiments. It should be noted that, unless otherwise expressly stated, "parts" and "%" in the following description refer to "parts by mass" and "% by mass," respectively.

[0162] <Preparation of Sample A and Sample B>

[0163] (1) Substrate treatment of inner layer circuit board

[0164] A copper-clad laminate (copper foil thickness 18μm, substrate thickness 0.8mm, Panasonic Electric Works Co., Ltd. "R5715ES") with copper on both sides of a glass cloth substrate and epoxy resin is etched to form circuit patterns on both sides, creating an inner layer circuit board with 30% in-plane copper area. The copper circuits of the obtained inner layer circuit board are roughened using a micro-etching agent (MEC Co., Ltd. "CZ-8100").

[0165] (2) Lamination of resin sheets

[0166] The resin sheets prepared in each embodiment were laminated onto both sides of the inner circuit board prepared in (1) above using a batch vacuum pressure laminator (MVLP-500, manufactured by Meiki Seisakusho Co., Ltd.). The lamination was performed by depressurizing for 30 seconds to bring the pressure down to below 13 hPa, and then pressing at 120°C for 30 seconds at a pressure of 0.74 MPa.

[0167] (3) Curing of resin sheets

[0168] The resin sheet was cured at 170°C for 60 minutes to form a reflective sheet, thus obtaining sample A.

[0169] (4) Heat resistance test treatment

[0170] Sample A was heated at 125°C for 100 hours to obtain sample B.

[0171] <Determination of Melt Viscosity>

[0172] 25 layers of resin composition were stacked to obtain a 1 mm thick resin composition layer. This 1 mm thick resin composition layer was then stamped into a 20 mm diameter sample to prepare a test specimen. For the prepared test specimen, the dynamic viscoelastic coefficient was measured using a dynamic viscoelasticity measuring device (UBM Rheogel-G3000) under the following conditions: initial temperature 60 °C to 200 °C, heating rate 5 °C / min, temperature interval 2.5 °C, and vibration frequency 1 Hz. The melt viscosity was then determined, and the results were evaluated according to the following criteria.

[0173] ○: Less than 5000 berths

[0174] △: 5000-10000 stops

[0175] ×: More than 10,000 berths.

[0176] <Flexible Evaluation>

[0177] The resin sheets prepared in each embodiment were bent 180 degrees along an axis with a diameter of 1 mm with the PET film with the release layer on the inside. The resin sheets without cracks were evaluated as "○" and the resin sheets with cracks were evaluated as "×".

[0178] <Determination of reflectivity after curing>

[0179] Sample A was cut into pieces 50 mm wide and 50 mm long. After grinding the cross-section, the reflectance of light at a wavelength of 460 nm was measured using a multichannel spectrometer (manufactured by Otsuka Electronics Co., Ltd., MCPD-7700). The results were evaluated according to the following criteria.

[0180] ○: Reflectivity exceeds 90%

[0181] △: Reflectivity is above 85% and below 90%

[0182] ×: Reflectivity is less than 85%.

[0183] <Determination of reflectivity after heat resistance test>

[0184] Sample B was cut into pieces 50 mm wide and 50 mm long. After grinding the cross-section, the reflectance of light at a wavelength of 460 nm was measured using a multichannel spectrometer (manufactured by Otsuka Electronics Co., Ltd., MCPD-7700). The results were evaluated according to the following criteria.

[0185] ○: Reflectivity exceeds 85%

[0186] △: Reflectivity is above 80% and below 85%

[0187] ×: Reflectivity is less than 80%.

[0188] <Example 1>

[0189] While stirring, 20 parts of liquid bisphenol-type epoxy resin ("ZX1059" manufactured by Nippon Steel Chemical Materials Co., Ltd., a 1:1 mixture of bisphenol A and bisphenol F, with an epoxy equivalent of 169 g / eq.), 50 parts of fluorine-containing phenoxy resin ("YL7876B40" manufactured by Mitsubishi Chemical Corporation, a MEK solution with a solid content of 40% by mass), 0.07 parts of antioxidant (butylated hydroxytoluene (BHT)), and 0.07 parts of ultraviolet absorber ("Chimassorb 81 FL" manufactured by BASF) were heated and dissolved in 60 parts of MEK. Mix 160 parts of white inorganic oxide (titanium oxide (average particle size 0.26 μm, "PX3788" manufactured by Sakai Chemical Co., Ltd., treated with aminosilane)) and 0.5 parts of curing accelerator (a solution obtained by adjusting the phosphorus catalyst ("TBP-DA-50M" manufactured by Hokuko Chemical Co., Ltd.) to 50% non-volatile components with MEK) and disperse evenly using a high-speed rotary mixer to prepare resin varnish A.

[0190] As a support, a PET film (PET501010 manufactured by Lintec Corporation, 38 μm thick) with a release layer is prepared. Resin varnish A is uniformly coated onto the release layer of this support so that the thickness of the dried resin composition layer is 50 μm. Then, resin varnish A is heated at 80°C for 4 minutes to obtain a resin sheet A comprising a resin composition layer with a thickness of 50 μm.

[0191] <Example 2>

[0192] In Example 1, 220 parts of liquid bisphenol type epoxy resin ("ZX1059" manufactured by Nippon Steel Chemical Materials Co., Ltd., a 1:1 mixture of bisphenol A and bisphenol F, with an epoxy equivalent of 169 g / eq.) were replaced with 20 parts of liquid epoxy resin ("HP820" manufactured by Mitsubishi Chemical Co., Ltd., with an epoxy equivalent of 200 g / eq.).

[0193] Except for the above, the same procedures as in Example 1 were followed to produce resin varnish B and resin sheet B.

[0194] <Example 3>

[0195] In Example 1, the amount of white inorganic oxide (titanium oxide (average particle size 0.26 μm, “PX3788” manufactured by Sakai Chemical Co., Ltd., treated with aminosilane)) was changed from 160 parts to 200 parts.

[0196] Except for the above, the same procedure as in Example 1 was performed to produce resin varnish C and resin sheet C.

[0197] <Example 4>

[0198] In Example 1, the amount of fluorine-containing phenoxy resin (YL7876B40 manufactured by Mitsubishi Chemical Corporation, a MEK solution with a solid content of 40% by mass) was changed from 50 parts to 30 parts, and 8 parts of solid fluorine-containing epoxy resin (epoxy equivalent 245 g / eq., YL7760 manufactured by Mitsubishi Chemical Corporation) were used.

[0199] Except for the above, the same procedures as in Example 1 were followed to produce resin varnish D and resin sheet D.

[0200] <Example 5>

[0201] In Example 1, 0.5 parts of curing accelerator (a solution obtained by adjusting the phosphorus catalyst (TBP-DA-50M manufactured by Hokuko Chemical Co., Ltd.) to 50% non-volatile components with MEK) were replaced with 3 parts of curing accelerator (a solution obtained by adjusting the imidazole catalyst (1B2PZ-10M, manufactured by Shikoku Chemical Co., Ltd.) to 10% non-volatile components with MEK).

[0202] Except for the above, the same procedures as in Example 1 were followed to produce resin varnish E and resin sheet E.

[0203] <Example 6>

[0204] In Example 1, the amount of curing accelerator (a solution obtained by adjusting the phosphorus catalyst (TBP-DA-50M manufactured by Hokuko Chemical Co., Ltd.) to 50% non-volatile components with MEK) was changed from 0.5 parts to 0.3 parts, and 1.5 parts of curing accelerator (a solution obtained by adjusting the imidazole catalyst (1B2PZ-10M, manufactured by Shikoku Kasei Co., Ltd.) to 10% non-volatile components with MEK) was used.

[0205] Except for the above, the same procedures as in Example 1 were followed to produce resin varnish F and resin sheet F.

[0206] <Example 7>

[0207] In Example 1, the amount of white inorganic oxide (titanium oxide (average particle size 0.26 μm, "PX3788" manufactured by Sakai Chemical Co., Ltd., treated with aminosilane)) was changed from 160 parts to 100 parts, and 60 parts of spherical silica (average particle size 0.5 μm, "SO-C2" manufactured by Yaduma Co., Ltd., treated with aminosilane) were used.

[0208] Except for the above, the same procedures as in Example 1 were followed to produce resin varnish G and resin sheet G.

[0209] <Example 8>

[0210] In Example 1, no 0.07 parts of antioxidant (butylated hydroxytoluene (BHT)) or UV absorber (Chimassorb 81 FL manufactured by BASF) were used.

[0211] Except for the above, the same procedures as in Example 1 were followed to produce resin varnish H and resin sheet H.

[0212] <Comparative Example 1>

[0213] In Example 1, 50 parts of fluorine-containing phenoxy resin (YL7876B40 manufactured by Mitsubishi Chemical Corporation, a MEK solution with a solid content of 40% by mass) were replaced with 50 parts of bisphenol A type phenoxy resin (1256B40 manufactured by Mitsubishi Chemical Corporation, a MEK solution with a solid content of 40% by mass).

[0214] Except for the above, the same procedures as in Example 1 were followed to produce resin varnish I and resin sheet I.

[0215] <Comparative Example 2>

[0216] In Example 1, 50 parts of fluorine-containing phenoxy resin (YL7876B40 manufactured by Mitsubishi Chemical Corporation, a MEK solution with a solid content of 40% by mass) were replaced with 20 parts of bisphenol A type phenoxy resin (1256B40 manufactured by Mitsubishi Chemical Corporation, a MEK solution with a solid content of 40% by mass), and 12 parts of solid fluorine-containing epoxy resin (epoxy equivalent 245 g / eq., YL7760 manufactured by Mitsubishi Chemical Corporation) were used.

[0217] Except for the above, the same procedures as in Example 1 were followed to produce resin varnish J and resin sheet J.

[0218] <Comparative Example 3>

[0219] In Example 1, 20 parts of liquid bisphenol type epoxy resin ("ZX1059" manufactured by Nippon Steel Chemical Materials Co., Ltd., a 1:1 mixture of bisphenol A and bisphenol F, with an epoxy equivalent of 169 g / eq.) were replaced with 20 parts of solid fluorine-containing epoxy resin ("YL7760" manufactured by Mitsubishi Chemical Co., Ltd., with an epoxy equivalent of 245 g / eq.).

[0220] Except for the above, the same procedures as in Example 1 were followed to produce resin varnish K and resin sheet K.

[0221] [Table 1]

[0222]

[0223] Explanation of symbols

[0224] 1 Printed wiring board

[0225] 2 substrate

[0226] 3. Reflective sheet

[0227] 31. Surface of the reflective sheet

[0228] 4. Light source

[0229] 10a Test tubes for determining liquid state

[0230] 10b Test tubes for temperature measurement

[0231] 13a Rubber stopper

[0232] 13b Rubber stopper

[0233] 14. Thermometer.

Claims

1. A resin composition comprising: (A) Epoxy resin that is liquid or semi-solid at 25°C (B) Phenoxy resins containing fluorine atoms, (C) White inorganic oxide, (D) Curing accelerators, and (E) Antioxidants, (D) contains phosphorus-based curing accelerators. When the non-volatile component in the resin composition is set at 100% by mass, the content of component (A) is 1% by mass or more and 20% by mass or less. When the non-volatile component in the resin composition is set at 100% by mass, the content of component (C) is 60% by mass or more. When the non-volatile component in the resin composition is set at 100% by mass, the content of component (D) is 0.01% by mass or more and 3% by mass or less. When the content of component (B) is set to 100% by mass in the resin composition, and the content of component (C) is set to 100% by mass in the resin composition, the ratio of B1 / C1 is 0.03 or more and 0.5 or less.

2. The resin composition according to claim 1, wherein, Phosphorus curing accelerators contain one or more selected from phosphonium salts and phosphine.

3. The resin composition according to claim 1, wherein, When the non-volatile component in the resin composition is set to 100% by mass, the content of component (C) is 75% by mass or more.

4. The resin composition according to claim 1, wherein, When the non-volatile component in the resin composition is set to 100% by mass, the content of component (C) is 95% by mass or less.

5. The resin composition according to claim 1, wherein, When the non-volatile component in the resin composition is set to 100% by mass, the content of component (C) is 80% by mass or less.

6. The resin composition according to claim 1, wherein, (C) The components are selected from aluminum oxide, titanium oxide, zirconium oxide, magnesium oxide and barium titanate.

7. The resin composition according to claim 1, wherein, (C) is composed of titanium oxide.

8. The resin composition according to claim 1, wherein, (C) The average particle size of the component is less than 2 μm.

9. The resin composition according to claim 1, wherein, When the non-volatile component in the resin composition is set to 100% by mass, the content of component (E) is 0.01% by mass or more.

10. The resin composition according to claim 1, wherein, When the non-volatile component in the resin composition is set to 100% by mass, the content of component (E) is 0.03% by mass or more.

11. The resin composition according to claim 1, wherein, When the non-volatile component in the resin composition is set to 100% by mass, the content of component (E) is less than 3% by mass.

12. The resin composition according to claim 1, wherein, When the non-volatile component in the resin composition is set to 100% by mass, the content of component (E) is less than 1% by mass.

13. The resin composition according to claim 1, further comprising (F) an ultraviolet absorber.

14. The resin composition according to claim 13, wherein, When the non-volatile component in the resin composition is set to 100% by mass, the content of component (F) is 0.01% by mass or more.

15. The resin composition according to claim 13, wherein, When the non-volatile component in the resin composition is set to 100% by mass, the content of component (F) is 0.03% by mass or more.

16. The resin composition according to claim 13, wherein, When the non-volatile component in the resin composition is set to 100% by mass, the content of component (F) is less than 1% by mass.

17. The resin composition according to claim 13, wherein, When the non-volatile component in the resin composition is set to 100% by mass, the content of component (F) is less than 0.1% by mass.

18. The resin composition according to claim 1, further comprising (H) silica.

19. The resin composition according to claim 18, wherein, When the non-volatile component in the resin composition is set to 100% by mass, the content of component (H) is 10% by mass or more.

20. The resin composition according to claim 18, wherein, When the non-volatile component in the resin composition is set to 100% by mass, the content of component (H) is 25% by mass or more.

21. The resin composition according to claim 18, wherein, When the non-volatile component in the resin composition is set to 100% by mass, the content of component (H) is 50% by mass or less.

22. The resin composition according to claim 18, wherein, When the non-volatile component in the resin composition is set to 100% by mass, the content of component (H) is 30% by mass or less.

23. The resin composition according to claim 1, used for light reflection.

24. The resin composition according to claim 1, wherein, When the non-volatile component in the resin composition is set to 100% by mass, the content of component (A) is 5% by mass or more.

25. The resin composition according to claim 1, wherein, When the non-volatile component in the resin composition is set to 100% by mass, the content of component (A) is less than 10% by mass.

26. The resin composition according to claim 1, wherein, When the non-volatile component in the resin composition is set to 100% by mass, the content of component (B) is 1% by mass or more.

27. The resin composition according to claim 1, wherein, When the non-volatile component in the resin composition is set to 100% by mass, the content of component (B) is 5% by mass or more.

28. The resin composition according to claim 1, wherein, When the non-volatile component in the resin composition is set to 100% by mass, the content of component (B) is 30% by mass or less.

29. The resin composition according to claim 1, wherein, When the non-volatile component in the resin composition is set to 100% by mass, the content of component (B) is 15% by mass or less.

30. The resin composition according to claim 1, wherein, When the non-volatile component in the resin composition is set to 100% by mass, the content of component (D) is 0.1% by mass or more.

31. The resin composition according to claim 1, wherein, When the non-volatile component in the resin composition is set to 100% by mass, the content of component (D) is less than 0.5% by mass.

32. The resin composition according to claim 1, wherein, B1 / C1 is above 0.

05.

33. A resin sheet comprising: Support body, and A resin composition layer comprising the resin composition according to any one of claims 1 to 32 is disposed on the support.

34. A reflective sheet comprising a cured product of the resin composition according to any one of claims 1 to 32.

35. A printed wiring board comprising the reflective sheet of claim 34.

Images