JP7176945B2 - Curable resin composition, dry film, cured product, wiring board and electronic component - Google Patents

Description

The present invention relates to a curable resin composition containing cellulose nanofibers, a dry film, a cured product, a wiring board and an electronic component.

Epoxy resins are used in paints, adhesives, It is used in a wide range of technical fields, including composite materials, molding materials, casting materials, various coating materials, interlayer insulation materials, and printed wiring board materials such as solder resists.

In particular, in printed wiring board materials, curable resin compositions containing epoxy resins are required to have even more excellent properties as wiring boards become more multi-functional. For example, as component mounting on wiring boards and wiring become more dense and thinner, curable resin compositions containing this epoxy resin have high electrical insulation, high thermal conductivity, and low linear thermal expansion (thermal dimension stability) and excellent flame retardancy.
In printed wiring board materials for semiconductor packages, the curable resin composition is used in the form of a dry film formed on a support film from the viewpoint of film thickness control.

On the other hand, an invention has been proposed in which a composite in which fine cellulose fibers are dispersed in a resin such as an epoxy resin is used as a wiring substrate (see Patent Document 1).
Epoxy resin compositions containing cellulose nanofibers are also expected to be used as encapsulants for light-emitting diodes due to their transparency.

JP 2012-119470 A

Indeed, the curable resin composition described in Patent Document 1 has specific cellulose fibers dispersed in a resin such as an epoxy resin, so it is lightweight and can be used like a glass epoxy substrate (FR-4). The substrate is less likely to crack due to glass fibers. Moreover, it is possible to obtain a cured product which is excellent in various properties inherent to epoxy resins.
However, in the curable resin composition described in Patent Document 1, especially when an epoxy resin composition containing cellulose nanofibers is used in the form of a dry film, depending on the method of hydrophobization treatment of cellulose nanofibers, Depending on the epoxy resin curing system, there are problems such as impairing the transparency of the cured product, cracks and streaks in the coating film when forming (coating and drying) on the support film, and brittle cured films after lamination. The inventors have newly noticed that the problem of becoming more likely to occur.

Therefore, the object of the present invention is to provide a dry film having excellent film-forming properties and transparency while maintaining excellent properties inherent in epoxy resins such as adhesiveness, mechanical properties, water resistance, chemical resistance, heat resistance, and electrical insulation. It is an object of the present invention to provide a curable resin composition suitable for obtaining an excellent cured product, a dry film and cured product using the curable composition, and a wiring board and electronic component using the cured product.

The inventors of the present invention have made intensive studies to achieve the above object, and have found that the dispersibility of fine cellulose fibers in epoxy resin is low and the fluidity of the resin composition is deteriorated. We focused on cracks and streaks during film formation (coating and drying) due to detachment and reaction with the curing component, and conducted further investigations. As a result, by adopting a curing system of an epoxy resin and an acid anhydride, and by using together cellulose nanofibers in which the carboxyl group is specifically modified to be hydrophobic, the chemically modified groups of the fine cellulose fibers are formed in the resin composition. It was found that it is possible to suppress the detachment and reaction with the curing component, the fluidity of the resin composition and excellent film-forming properties can be obtained, and the cured product with excellent transparency without coloring or turbidity can be obtained. I have completed my invention.

That is, the present invention is a curable resin composition containing an epoxy resin, an acid anhydride, and cellulose nanofibers,
A curable resin composition is provided, wherein the cellulose nanofibers have a structure represented by Formula 1 below.
R ₁ in the following formula 1 is a saturated or unsaturated, cyclic, linear or branched hydrocarbon group, and R ₂ is hydrogen or a saturated or unsaturated cyclic, linear or It is a branched hydrocarbon group.
(Formula 1)

R ₁ may be a hydrocarbon group having 3 to 18 carbon atoms. R ₂ may be hydrogen.

The acid anhydride may be an alicyclic compound.

The epoxy resin may be an alicyclic compound.

The present invention also provides a dry film, characterized by having a resin layer formed by applying or impregnating the curable resin composition on the film and drying the film.

The present invention also provides a cured product obtained by curing the curable resin composition or the dry film.

Moreover, this invention provides the wiring board characterized by including the said hardened|cured material.

Moreover, this invention provides the electronic component characterized by including the said hardened|cured material.

According to the present invention, while maintaining excellent properties such as adhesiveness, mechanical properties, water resistance, chemical resistance, heat resistance, and electrical insulation as a cured product of an epoxy resin, the film-forming properties and transparency as a dry film can be achieved. It is possible to provide a curable resin composition suitable for obtaining a cured product having excellent properties, a dry film and a cured product using the curable composition, and a wiring board and an electronic component using the cured product.

In addition, when isomers exist in the described compounds, all possible isomers can be used in the present invention unless otherwise specified.

<<<Curable Resin Composition>>>
A curable resin composition according to the present invention contains an epoxy resin, an acid anhydride, and cellulose nanofibers (sometimes abbreviated as CNF).

The curable resin composition according to the present invention is described in detail below.

<<Curable Resin>>
The curable resin composition according to the present invention contains an epoxy resin as a thermosetting resin.

The epoxy resin according to the present invention is not particularly limited. Epoxy resins include bisphenol-type epoxy resins such as bisphenol A-type epoxy resin, bisphenol F-type epoxy resin, bisphenol S-type epoxy resin, bisphenol E-type epoxy resin, bisphenol M-type epoxy resin, bisphenol P-type epoxy resin, and bisphenol Z-type epoxy resin. Novolac epoxy resins such as epoxy resins, bisphenol A novolak epoxy resins, phenol novolak epoxy resins, cresol novolak epoxy resins, biphenyl epoxy resins, biphenyl aralkyl epoxy resins, arylalkylene epoxy resins, tetraphenylolethane epoxy resins resins, naphthalene-type epoxy resins, anthracene-type epoxy resins, phenoxy-type epoxy resins, dicyclopentadiene-type epoxy resins, norbornene-type epoxy resins, trihydroxyphenylmethane-type epoxy resins, hydantoin-type epoxy resins, tetraphenylolethane-type epoxy resins, Bromated epoxy resin, hydrogenated (bisphenol) type resin, glycidylamine type epoxy resin, alicyclic epoxy resin, diglycidyl phthalate resin, tetraglycidyl xylenoyl ethane resin, glycidyl methacrylate copolymer epoxy resin, cyclohexylmaleimide and Copolymerized epoxy resin with glycidyl methacrylate, epoxy-modified polybutadiene rubber derivative, CTBN-modified epoxy resin, trimethylolpropane polyglycidyl ether, phenyl-1,3-diglycidyl ether, 1,6-hexanediol diglycidyl ether, ethylene Epoxy resins such as diglycidyl ether of glycol or propylene glycol, sorbitol polyglycidyl ether, tris(2,3-epoxypropyl)isocyanurate, and triglycidyltris(2-hydroxyethyl)isocyanurate. These epoxy resins can be used alone or in combination of two or more. From the viewpoint of the transparency of the cured product, epoxy resins having an alicyclic structure or an epoxy group-containing monomer or oligomer having an aliphatic chain structure, and more preferably an epoxy resin having an alicyclic structure.

Examples of commercially available epoxy resins include jER828, jER834, jER1001, and jER1004 manufactured by Mitsubishi Chemical Corporation; Epiclon 840, Epiclon 850, Epiclon 1050, and Epiclon 2055 manufactured by DIC Corporation; YD-011, YD-013, YD-127, YD-128, Dow Chemical Company D.I. E. R. 317, D. E. R. 331, D. E. R. 661, D. E. R. 664, Sumitomo Chemical Co., Ltd. Sumie-epoxy ESA-011, ESA-014, ELA-115, ELA-128, Asahi Chemical Co., Ltd. A. E. R. 330, A. E. R. 331, A. E. R. 661, A. E. R. 664, etc. (both trade names); jERYL903 manufactured by Mitsubishi Chemical Corporation; Epiclon 152 and Epiclon 165 manufactured by DIC Corporation; Dow Chemical Company's D.I. E. R. 542, Sumie-Epoxy ESB-400 and ESB-700 manufactured by Sumitomo Chemical Co., Ltd., A.M.D. manufactured by Asahi Chemical Industry Co., Ltd. E. R. 711, A. E. R. Brominated epoxy resins such as 714 (all trade names); jER152 and jER154 manufactured by Mitsubishi Chemical Corporation; E. N. 431, D. E. N. 438, Epiclon N-730, Epiclon N-770, Epiclon N-865 manufactured by DIC Corporation, Epotote YDCN-701, YDCN-704 manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., EPPN-201 manufactured by Nippon Kayaku Co., Ltd., EOCN-1025, EOCN-1020, EOCN-104S, RE-306, Sumitomo Chemical Co., Ltd. Sumie-Epoxy ESCN-195X, ESCN-220, Asahi Chemical Industry Co., Ltd. A. E. R. ECN-235, ECN-299, etc. (both trade names) novolac type epoxy resins; Epiclon 830 manufactured by DIC Corporation, jER807 manufactured by Mitsubishi Chemical Corporation, Epotote YDF-170 and YDF-175 manufactured by Nippon Steel & Sumikin Chemical Co., Ltd. , YDF-2004, etc. (all trade names); Hydrogenated bisphenol A epoxy resins such as Epotato ST-2004, ST-2007, ST-3000 (trade names) manufactured by Nippon Steel & Sumikin Chemical Co., Ltd. ; Mitsubishi Chemical Co., Ltd. jER604, Nippon Steel & Sumikin Chemical Co., Ltd. Epototo YH-434, Sumitomo Chemical Co., Ltd. Sumi-Epoxy ELM-120, etc. (all trade names) glycidylamine type epoxy resin; hydantoin type Epoxy resin; alicyclic epoxy resin such as Celoxide 2021P (trade name) manufactured by Daicel Corporation; YL-933 manufactured by Mitsubishi Chemical Corporation; E. N. , EPPN-501, EPPN-502, etc. (all trade names); trihydroxyphenylmethane-type epoxy resins; Xylenol-type or biphenol-type epoxy resins or mixtures thereof; EBPS-200 manufactured by Nippon Kayaku Co., Ltd., EPX-30 manufactured by Asahi Denka Kogyo Co., Ltd., and bisphenol S-type epoxy such as EXA-1514 (trade name) manufactured by DIC Corporation Resin; bisphenol A novolak type epoxy resin such as jER157S (trade name) manufactured by Mitsubishi Chemical Co., Ltd.; tetraphenylol ethane type epoxy resin such as jERYL-931 (both trade names) manufactured by Mitsubishi Chemical Co.; Heterocyclic epoxy resins such as TEPIC (trade name) manufactured by Co., Ltd.; diglycidyl phthalate resins such as BLEMMER DGT manufactured by NOF Corporation; tetraglycidyl xylenoyl ethane resins such as ZX-1063 manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.; ESN-190, ESN-360 manufactured by Nippon Steel Chemical Co., Ltd.; HP-4032, EXA-4750, EXA-4700 manufactured by DIC Corporation; naphthalene group-containing epoxy resins; Epoxy resins having a cyclopentadiene skeleton; Glycidyl methacrylate copolymer epoxy resins such as CP-50S and CP-50M manufactured by NOF Corporation; Copolymer epoxy resins of cyclohexylmaleimide and glycidyl methacrylate; Epoxy-modified polybutadiene rubber derivatives (eg, PB-3600 manufactured by Daicel Chemical Industries, Ltd.), CTBN-modified epoxy resins (eg, YR-102, YR-450, etc. manufactured by Tohto Kasei Co., Ltd.), and the like.

The content of the epoxy resin may be, for example, 50% by mass or more, 90% by mass or more, 95% by mass or more, or 99% by mass or more with respect to the total thermosetting resin. Alternatively, it may be 1% by mass or more and 90% by mass or less, 10% by mass or more and 85% by mass or less, or 20% by mass or more and 80% by mass or less.

<<Curing agent>>
The curable resin composition according to the present invention contains an acid anhydride as a curing agent.

The acid anhydride according to the invention is not particularly limited. Examples of acid anhydrides include phthalic anhydride, maleic anhydride, trimellitic anhydride, pyromellitic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, methylnadic anhydride, nadic anhydride, hetic anhydride, and dodecenyl. succinic anhydride, glutaric anhydride, methyl nadic anhydride, methylhexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, trialkyltetrahydrophthalic anhydride, methyldihydronadic anhydride, cyclopentanetetracarboxylic acid dianhydride, bicyclo(2 2.2) octo-7-2,3,5,6-tetracarboxylic acid dianhydride and the like. These can be used alone or in combination of two or more. The acid anhydride is preferably an acid anhydride having an alicyclic structure from the viewpoint of heat resistance, mechanical properties and transparency of the cured product.

Examples of commercially available acid anhydrides include MT500 manufactured by DIC Corporation as methyltetrahydrophthalic anhydride; Rikacid HH manufactured by Shin Nippon Rika Co., Ltd. as hexahydrophthalic anhydride; As hydrophthalic anhydride, B-570 and B-650 manufactured by DIC Corporation; as a mixture of hexahydrophthalic anhydride and methylhexahydrophthalic acid, methylhexahydrophthalic anhydride: hexahydrophthalic anhydride = 70:30. MCD manufactured by Nippon Kayaku Co., Ltd. as methyl nadic anhydride; YH-306 manufactured by Mitsubishi Chemical Corporation as trialkyltetrahydrophthalic anhydride;

As for the content of acid anhydride, the ratio of acid anhydride equivalent/epoxy equivalent is preferably 0.7 to 1.4, more preferably 0.8 to 1.2. Within this range, the cured product can have excellent heat resistance, mechanical properties and transparency.

The curable resin composition according to the present invention may contain a curing agent other than the acid anhydride as long as the effects of the present invention are not impaired. Other curing agents include phenolic resins such as phenolic novolac resin, cresol novolac resin, bisphenol A novolak resin, and resol-type phenolic resin; , melamine resin, dicyandiamide, other amine-based (imidazole, tertiary amine) and other amine-based compounds; mercaptan-based compounds; cyanate ester resins, active ester resins; resins having a benzoxazine ring; Modified products of

<<Cellulose Nanofiber>>
CNF according to the present invention includes the structure of the following formula 1 in its structure.

(Formula 1)

R ₁ in Formula 1 is not particularly limited as long as it is a saturated or unsaturated, cyclic, linear or branched hydrocarbon group. R ₂ in Formula 1 is not particularly limited as long as it is hydrogen or a saturated or unsaturated, cyclic, linear or branched hydrocarbon group. R ₁ in Formula 1 is preferably a hydrocarbon group having 1 to 30 carbon atoms, more preferably a hydrocarbon group having 3 to 18 carbon atoms. Preferably, R ₂ in Formula 1 is hydrogen. In the case of such a structure, excellent film-forming properties can be achieved without streaks or cracks during film formation.

A hydrocarbon group having 1 carbon atom, or a saturated or unsaturated cyclic, linear or branched hydrocarbon group having 2 to 30 carbon atoms can be mentioned. Specific examples include the following hydrocarbon groups.

A methyl group is mentioned as a hydrocarbon group of carbon number 1.

Saturated, linear hydrocarbon groups having 2 to 30 carbon atoms include ethyl, propyl, butyl, pentyl, hexyl, octyl, nonyl, decyl, dodecyl, octadecyl, and docosyl. and octacosanyl groups.

Unsaturated straight chain hydrocarbon groups having 2 to 30 carbon atoms include oleyl, myristoleyl, palmitoleyl, linoleyl, linolenyl and eicosanyl groups.

Saturated, branched hydrocarbon groups having 2 to 30 carbon atoms include isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, tert-pentyl, isohexyl and 2-hexyl. group, dimethylbutyl group, and ethylbutyl group.

Examples of unsaturated branched hydrocarbon groups having 2 to 30 carbon atoms include isopropylene group, isobutylene group, sec-butylene group, tert-butylene group, isopentylene group, tert-pentylene group, isohexylene group, 2 -hexylene group, dimethylbutylene group, and ethylbutylene group.

Examples of saturated cyclic hydrocarbon groups having 2 to 30 carbon atoms include cyclopentyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, cycloundecyl, and cyclo Alicyclic hydrocarbon groups such as dodecyl group, cyclotridecyl group, cyclotetradecyl group, cyclopentadecyl group, cyclohexadecyl group, cycloheptadecyl group and cyclooctadecyl group can be mentioned.

The unsaturated cyclic hydrocarbon group having 3 to 30 carbon atoms includes a cyclopropylene group, a cyclobutylene group, a cyclopentylene group, a cyclohexylene group, a cycloheptylene group, a cyclooctylene group, a cyclononylene group, and a cyclodecylene group. , cycloundecylene group, cyclododecylene group, cyclotridecylene group, cyclotetradecylene group, cyclopentadecylene group, cyclohexadecylene group, cycloheptadecylene group, cyclooctadecylene group, etc. Hydrogen group; Aromatic hydrocarbon group such as benzene group, naphthalene group, anthracene group; .

Specific examples of the aryl group include phenyl group, naphthyl group, anthryl group, phenanthryl group, biphenyl group, and triphenyl group, and these may be used singly or in combination of two or more. Among them, phenyl group, naphthyl group, and biphenyl group are preferred, and phenyl group is more preferred, from the viewpoint of compatibility with the resin.

The aralkyl group specifically includes a benzyl group, a phenethyl group, a phenylpropyl group, a phenylpentyl group, a phenylhexyl group, and a phenylheptyl group, and these may be used singly or in combination of two or more. Among them, benzyl group, phenethyl group, phenylpropyl group, phenylpentyl group and phenylhexyl group are preferable, and benzyl group, phenethyl group, phenylpropyl group and phenylpentyl group are more preferable from the viewpoint of compatibility with the resin.

In addition, the above aryl group and aralkyl group may have a substituent, and examples of the substituent include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert- Alkyl groups having 1 to 6 carbon atoms such as butyl, pentyl, isopentyl and hexyl; methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, sec-butoxy and tert-butoxy , pentyloxy group, isopentyloxy group, alkoxy group having 1 to 6 carbon atoms such as hexyloxy group; methoxycarbonyl group, ethoxycarbonyl group, propoxycarbonyl group, isopropoxycarbonyl group, butoxycarbonyl group, isobutoxycarbonyl group, alkoxycarbonyl groups having 1 to 6 carbon atoms such as sec-butoxycarbonyl group, tert-butoxycarbonyl group, pentyloxycarbonyl group and isopentyloxycarbonyl group; halogen atoms such as fluorine atom, chlorine atom, bromine atom and iodine atom; Examples include acyl groups, aralkyl groups, and aralkyloxy groups having 1 to 6 carbon atoms.

The number of carbon atoms in the saturated or unsaturated cyclic, linear or branched hydrocarbon group is arbitrarily selected depending on the combination with the curable resin, but is preferably 1 or more, especially 3 or more, especially 10 or more. It is preferably 30 or less, particularly 20 or less, especially 18 or less. For example, it is preferably from 1 to 30, preferably from 3 to 20, particularly preferably from 3 to 18, and even more preferably from 10 to 18. When the number of carbon atoms is within the above range, the CNF and the curable resin are in a uniform mixed state, the curable resin composition has high film-forming properties, and the cured product has excellent transparency. can.

The amount of hydrophobized CNF in the curable resin composition according to the present invention is preferably 0.1 parts by mass or more and 30 parts by mass or less, more preferably 100 parts by mass based on the total amount of the curable resin (based on solid content). is 1 part by mass or more and 20 parts by mass or less, more preferably 2 parts by mass or more and 10 parts by mass or less. When the amount is 0.1 part by mass or more, the film-forming property of the curable resin composition is high, and when it is 30 parts by mass or less, the film-forming property of the curable resin composition is high, and the cured product is excellent. It can have transparency.

Natural cellulose fibers used as raw materials include, for example, wood pulp such as softwood pulp and hardwood pulp; cotton pulp such as cotton linter and cotton lint; non-wood pulp such as straw pulp and bagasse pulp; and bacterial cellulose. These can be used alone or in combination of two or more.

The raw material is mainly composed of cellulose, hemicellulose and lignin, and the content of lignin is usually about 0 to 40% by mass, particularly about 0 to 10% by mass. As for these raw materials, if necessary, lignin can be removed or bleached to adjust the amount of lignin. In addition, the measurement of lignin content can be performed by the Klason method.

In the cell walls of plants, cellulose molecules are not monomolecular but are regularly aggregated to form crystalline microfibrils consisting of dozens of microfibrils, which are the basic skeletal substance of plants. Therefore, in order to produce CNF from the raw material, the raw material is subjected to beating or crushing treatment, high-temperature and high-pressure steam treatment, treatment with phosphate, etc., so that the fibers can be unraveled to nanosize. .

In addition, by subjecting the natural cellulose fiber to oxidation treatment (for example, oxidation treatment using TEMPO described later), the primary hydroxyl group at the C6 position in the glucopyranose ring of natural cellulose is selectively converted to a carboxyl group. A carboxyl group-containing cellulose fiber can be obtained by oxidation. By performing this treatment, the cellulose fibers can be unraveled to nano-size (carboxyl group-containing CNF) with a relatively weak shearing force.

Furthermore, hydrophobized CNF can be obtained by modifying the carboxyl group of carboxyl group-containing CNF with an amine compound to make it hydrophobic.

(Slurry process)
First, a slurry is prepared by dispersing natural cellulose fibers in water. The slurry is prepared by adding about 10 to 1000 times the amount (based on mass) of water to the raw material natural cellulose fiber (absolute dry basis: mass of natural cellulose fiber after drying by heating at 150 ° C. for 30 minutes), It can be obtained by processing with a mixer or the like. The natural cellulose fibers may be subjected to a treatment such as beating to increase the surface area. Moreover, the cellulose type I crystallinity of the commercially available pulp is usually 80% or more.

(Oxidation treatment step)
Next, the natural cellulose fibers are oxidized in the presence of an oxidizing agent such as an N-oxyl compound to obtain carboxyl group-containing cellulose fibers (hereinafter sometimes simply referred to as "oxidation treatment").

As the N-oxyl compound, one or more heterocyclic N-oxyl compounds selected from piperidineoxyl compounds having an alkyl group having 1 or 2 carbon atoms, pyrrolidineoxyl compounds, imidazolineoxyl compounds, and azaadamantane compounds. preferable. Among these, piperidineoxyl compounds having an alkyl group having 1 or 2 carbon atoms are preferred from the viewpoint of reactivity, and 2,2,6,6-tetraalkylpiperidine-1-oxyl (TEMPO), 4-hydroxy- 2,2,6,6-tetraalkylpiperidine-1-oxyl, 4-alkoxy-2,2,6,6-tetraalkylpiperidine-1-oxyl, 4-benzoyloxy-2,2,6,6-tetra Alkylpiperidine-1-oxyl, di-tert-alkylnitroxyl compounds such as 4-amino-2,2,6,6-tetraalkylpiperidine-1-oxyl, 4-acetamido-TEMPO, 4-carboxy-TEMPO, 4 -Phosphonoxy-TEMPO and the like. Among these piperidineoxyl compounds are 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl, 4- Methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl is more preferred, and 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) is even more preferred.

The amount of the N-oxyl compound may be a catalytic amount, and is preferably 0.001 to 10 parts by mass, more preferably 0.01 to 9 parts by mass, relative to 100 parts by mass of natural cellulose fiber (absolute dry basis). parts by mass, more preferably 0.1 to 8 parts by mass, and even more preferably 0.5 to 5 parts by mass.

Oxidizing agents other than N-oxyl compounds can be used in the oxidation treatment of natural cellulose fibers. As the oxidizing agent, oxygen or air, peroxides; halogens, hypohalous acids, halogenous acids, perhalogenates and their alkali metals are selected from the viewpoint of solubility and reaction rate when the solvent is adjusted to an alkaline range. salts or alkaline earth metal salts; halogen oxides, nitrogen oxides and the like. Among these, alkali metal hypohalites are preferred, and specific examples include sodium hypochlorite and sodium hypobromite. The amount of the oxidizing agent to be used may be selected according to the degree of carboxyl group substitution (oxidation degree) of the natural cellulose fiber. It is preferably in the range of about 1 to 100 parts by weight per 100 parts by weight of natural cellulose fiber (absolute dry basis).

In addition, bromide such as sodium bromide and potassium bromide, iodide such as sodium iodide and potassium iodide, and the like can be used as a co-catalyst in order to perform the oxidation reaction more efficiently. The amount of co-catalyst is not particularly limited as long as it is an effective amount capable of exhibiting its function.

The reaction temperature in the oxidation treatment is preferably 50° C. or lower, more preferably 40° C. or lower, and still more preferably 20° C. or lower, from the viewpoint of reaction selectivity and suppression of side reactions. It is preferably -5°C or higher.

Further, the pH of the reaction system is preferably adjusted to the properties of the oxidizing agent. For example, when sodium hypochlorite is used as the oxidizing agent, the pH of the reaction system is preferably alkaline, preferably pH 7 to 13, and pH 10. ~13 is more preferred. Furthermore, the reaction time is desirably 1 to 240 minutes.

By performing the oxidation treatment, the carboxyl group content is preferably 0.1 mmol/
A carboxyl group-containing cellulose fiber having a weight of more than g is obtained.

(Refining process)
The carboxyl group-containing cellulose fibers obtained in the oxidation treatment step contain N-oxyl compounds such as TEMPO used as catalysts and by-product salts. Although the next step may be performed as it is, it is also possible to obtain carboxyl group-containing cellulose fibers with high purity by performing purification. As the purification method, an optimum method can be adopted depending on the kind of solvent in the oxidation reaction, the degree of oxidation of the product, and the degree of purification. For example, reprecipitation using water as a good solvent, methanol, ethanol, acetone, etc. as a poor solvent, extraction of TEMPO into a solvent such as hexane that phase separates from water, ion exchange of salts, purification by dialysis, etc. is mentioned.

(Miniaturization process)
Next, a step of refining the carboxyl group-containing cellulose fibers obtained after the purification step is performed. In the micronization step, it is preferable to disperse the carboxyl group-containing cellulose fibers that have undergone the purification step in a solvent and perform a micronization treatment. By performing this refinement step, carboxyl group-containing CNF having an average aspect ratio within the above range can be obtained.

Solvents as dispersion media include water, alcohols having 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms such as methanol, ethanol and propanol; ketones having 3 to 6 carbon atoms such as acetone, methyl ethyl ketone and methyl isobutyl ketone. linear or branched saturated or unsaturated hydrocarbons having 1 to 6 carbon atoms; aromatic hydrocarbons such as benzene and toluene; halogenated hydrocarbons such as methylene chloride and chloroform; lower hydrocarbons having 2 to 5 carbon atoms Alkyl ethers; polar solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide, and diesters of succinic acid and triethylene glycol monomethyl ether; These can be used alone or in combination of two or more. A polar solvent such as a lower alkyl ether of 1 to 5, N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide, and methyl triglycol diester succinate is preferred, and water is more preferred from the viewpoint of reducing environmental load. The amount of the solvent to be used is not particularly limited as long as it is an effective amount capable of dispersing the carboxyl group-containing cellulose fibers. It can be used in multiples of mass.

A known dispersing machine is preferably used as a device used in the fine processing. For example, a disaggregator, a beater, a low-pressure homogenizer, a high-pressure homogenizer, a grinder, a cutter mill, a ball mill, a jet mill, a single-screw extruder, a twin-screw extruder, an ultrasonic stirrer, a household juicer mixer, and the like can be used. In addition, the solid content concentration of the reactant fiber in the pulverization treatment is preferably 50% by mass or less.

Moreover, in the present invention, at least one treatment selected from biochemical treatment, chemical treatment, and mechanical treatment can be further performed before performing the above-described miniaturization treatment. Specific examples include acid hydrolysis, hydrothermal decomposition, oxidative decomposition, pulverization, enzymatic treatment, UV treatment, electron beam treatment, and the like. , the miniaturization process can be performed more efficiently, and the average aspect ratio is within the above range. Examples of the treatment include a method of refluxing the carboxyl group-containing cellulose fibers that have undergone the refining step with an acid. The type and concentration of acid are not particularly limited. For example, a method of adding concentrated hydrochloric acid and heating an aqueous dispersion of carboxyl group-containing cellulose fibers having a hydrochloric acid concentration of 0.1 to 10M is exemplified.

As the form of the obtained carboxyl group-containing CNF, if necessary, the solid content concentration is adjusted suspension form (visually colorless transparent or opaque liquid), or dried powder form (however, CNF aggregated powder, which does not mean cellulose particles). When making a suspension, only water may be used as a dispersion medium, and a mixed solvent of water and other organic solvents (e.g., alcohols such as ethanol), surfactants, acids, bases, etc. may be used. may be used.

As described above, the hydroxyl group at the C6 position of the cellulose structural unit is selectively oxidized to a carboxyl group via an aldehyde group, and the carboxyl group content is 0.1 mmol/g or more, and the average fiber diameter is of 0.1 to 200 nm, an average fiber length of 600 nm or less, and an average aspect ratio of 1 to 200, preferably CNF having a crystallinity of 30% or more.

[Average fiber diameter, average fiber length and average aspect ratio of CNF]
The average fiber diameter, average fiber length and average aspect ratio of carboxyl group-containing CNF can be measured as follows.

Water is added to carboxyl group-containing CNF to prepare a dispersion having a concentration of 0.0001% by mass, and the dispersion is dropped on mica (mica) and dried as an observation sample, using an atomic force microscope. (AFM, Nanoscope III Tapping mode AFM, manufactured by Digital Instruments, using Point Probe (NCH) manufactured by Nanosensors) is used to measure the fiber height of CNF in the observation sample. At that time, 5 or more CNFs are extracted from a microscope image in which CNFs can be confirmed, and the average fiber diameter is calculated from the fiber heights thereof. Also, the average fiber length is calculated from the distance in the fiber direction. The average aspect ratio is calculated from average fiber length/average fiber diameter.

In the present invention, the average fiber diameter of the carboxyl group-containing CNF is, for example, 0.1 nm or more and 200 nm or less, preferably 1 nm or more and 100 nm or less, more preferably 2 nm or more and 50 nm or less, still more preferably 2.5 nm or more and 20 nm or less. be. If the average fiber diameter is less than 0.1 nm, it is difficult to produce, and by setting the average fiber diameter to 200 nm or less, it is possible to obtain a cured product that has good adhesion to the conductor of the printed wiring board.

The average fiber length of the carboxyl group-containing CNF is, for example, 600 nm or less, preferably 50 nm or more and 600 nm or less, more preferably 100 nm or more and 500 nm or less, still more preferably 100 nm or more and 400 nm or less. When the average fiber length is within such a range, the composition can be easily dispersed.

The average aspect ratio of the carboxyl group-containing CNF is, for example, 1 or more and 200 or less, preferably 5 or more and 180 or less, more preferably 9 or more and 170 or less, and particularly preferably 9 or more and less than 100. If the average aspect ratio is less than 1, it is difficult to manufacture. If the average aspect ratio is 200 or less, the adhesion between the metal conductor and the cured product is good, and the smaller the average aspect ratio, the better the adhesion between the metal conductor and the cured product. The adhesiveness of the composition is excellent, and the viscosity of the composition can be lowered.

In addition, in the method for modifying a carboxyl group described later, these average fiber diameter, average fiber length and average aspect ratio are maintained even after modification.

(Method for modifying carboxyl group of CNF)
Cellulose nanofibers having the structure of Formula 1 can be obtained by modifying the carboxyl groups of the CNFs having the carboxyl groups described above with a predetermined compound. Examples of the method for modifying the carboxyl group of CNF in the present invention include a method of amidating CNF having a carboxyl group and an amine compound having a modifying group (R1 and R2 in Formula 1) in a solvent. Since CNF having a carboxyl group is highly hydrophilic, when it is added to a resin composition such as that of the present invention, it is preferable to enhance affinity with the resin by such modification.

The amount of the amine compound having the modifying group to be used can be determined depending on the desired binding amount in the hydrophobized CNF. The amino group is preferably 0.1 mol or more, more preferably 0.5 mol or more, still more preferably 0.7 mol or more, still more preferably 1 mol or more, and from the viewpoint of product purity, preferably 50 mol or less, more preferably The amount used is 20 mol or less, more preferably 10 mol or less. In addition, the amount of amine included in the above range may be subjected to the reaction all at once, or may be divided and subjected to the reaction.

A known condensing agent can also be used in the reaction between the carboxyl group-containing CNF and the amine compound having a modifying group.
The condensing agent is not particularly limited. -dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (hereinafter sometimes referred to as "DMT-MM") and the like.

In the above condensation reaction, it is preferable to select a solvent in which the amine compound to be used is dissolved. , N-dimethylacetamide, tetrahydrofuran (THF), diester of succinic acid and triethylene glycol monomethyl ether, acetone, methyl ethyl ketone (MEK), acetonitrile, dichloromethane, chloroform, toluene, acetic acid, etc., and one of these alone or in combination of two or more. Among these polar solvents, diesters of succinic acid and triethylene glycol monomethyl ether, ethanol and DMF are preferred.

The reaction time and reaction temperature in the above condensation reaction can be appropriately selected according to the type of amine and solvent used, etc., but from the viewpoint of reaction rate and productivity, it is preferably 1 to 24 hours, more preferably 10 to 10 hours. 20 hours. From the viewpoint of reactivity, the reaction temperature is preferably 0° C. or higher, more preferably 5° C. or higher, and even more preferably 10° C. or higher. In addition, from the viewpoint of coloring of hydrophobized CNF, the temperature is preferably 200° C. or lower, more preferably 80° C. or lower, and still more preferably 30° C. or lower.

After the above mixing and after the reaction, a post-treatment may be appropriately carried out in order to remove unreacted amine compounds, condensing agents, and the like. As a post-treatment method, for example, filtration, centrifugation, dialysis, or the like can be used.

Specific examples of the amine having a saturated or unsaturated cyclic or linear or branched hydrocarbon group include primary amines such as methylamine, ethylamine, propylamine, isopropylamine, and butylamine. , hexylamine, octylamine, decylamine, dodecylamine, octadecylamine and oleylamine. Examples of secondary amines include dialkylamines such as dimethylamine, diethylamine, dibutylamine and dioctadecylamine.

In addition, the amine having an aromatic hydrocarbon group may have a total carbon number of 6 to 20, and may be either a primary amine or a secondary amine. , primary amines are preferred. Also, the number of aromatic hydrocarbon groups in the amine may be either one or two as long as the total number of carbon atoms is 6-20, but one is preferred.

Amines having an aromatic hydrocarbon group include amines having an aryl group and amines having an aralkyl group, and amines having an aryl group are preferred from the viewpoint of compatibility with resins.

Specific examples of the aryl group include phenyl group, naphthyl group, anthryl group, phenanthryl group, biphenyl group, and triphenyl group, and these may be used singly or in combination of two or more. Among them, phenyl group, naphthyl group, and biphenyl group are preferred, and phenyl group is more preferred, from the viewpoint of compatibility with the resin.

The aralkyl group specifically includes a benzyl group, a phenethyl group, a phenylpropyl group, a phenylpentyl group, a phenylhexyl group, and a phenylheptyl group, and these may be used singly or in combination of two or more. Among them, benzyl group, phenethyl group, phenylpropyl group, phenylpentyl group and phenylhexyl group are preferable, and benzyl group, phenethyl group, phenylpropyl group and phenylpentyl group are more preferable from the viewpoint of compatibility with the resin.

In addition, the above aryl group and aralkyl group may have a substituent, and examples of the substituent include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert- Alkyl groups having 1 to 6 carbon atoms such as butyl, pentyl, isopentyl and hexyl; methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, sec-butoxy and tert-butoxy , pentyloxy group, isopentyloxy group, alkoxy group having 1 to 6 carbon atoms such as hexyloxy group; methoxycarbonyl group, ethoxycarbonyl group, propoxycarbonyl group, isopropoxycarbonyl group, butoxycarbonyl group, isobutoxycarbonyl group, alkoxycarbonyl groups having 1 to 6 carbon atoms such as sec-butoxycarbonyl group, tert-butoxycarbonyl group, pentyloxycarbonyl group and isopentyloxycarbonyl group; halogen atoms such as fluorine atom, chlorine atom, bromine atom and iodine atom; Examples include acyl groups, aralkyl groups, and aralkyloxy groups having 1 to 6 carbon atoms.

Specific examples of the amines having an aromatic hydrocarbon group include aniline, toluylamine, 4-biphenylylamine, diphenylamine, 2-aminonaphthalene, p-terphenylamine, 2 -aminoanthracene, 2-aminoanthraquinone. Among them, aniline, toluylamine, 4-biphenylylamine, diphenylamine, and 2-aminonaphthalene are preferred, and aniline is more preferred, from the viewpoint of compatibility with the resin. Amines having an aralkyl group include benzylamine, phenethylamine, 3-phenylpropylamine, 5-phenylpentylamine, 6-phenylhexylamine, 7-phenylheptylamine and 8-phenyloctylamine. Among them, benzylamine, phenethylamine, 3-phenylpropylamine, 5-phenylpentylamine, 6-phenylhexylamine and 7-phenylheptylamine are preferred from the same viewpoint, and benzylamine, phenethylamine, 3-phenylpropylamine and 5-phenylpentyl. More preferred are amines and 6-phenylhexylamine, and more preferred are benzylamine, phenethylamine, 3-phenylpropylamine and 5-phenylpentylamine. The aromatic hydrocarbon group-containing amine used in the present invention may be prepared according to a known method, or may be a commercial product.

In addition, amines obtained by adding a desired amount of ethylene oxide or propylene oxide to propylene glycol alkyl ether and aminated at the hydroxyl group end, amines having hydrophilic groups such as hydroxyethyl group and hydroxypropyl group, ethylene glycol and propylene glycol. and polyether chains such as lactide and caprolactone. It is preferably used as a compound that binds through a bond.

Methods for modifying carboxyl groups include methods using quaternary ammonium compounds in addition to methods using amine compounds. Like CNF according to the present invention, when a modification method with an amine compound is carried out, the modification group, which is the hydrocarbon group, binds to the cellulose main chain via an amide bond (covalent bond), whereas the fourth When the modification method with a class ammonium compound is carried out, it differs in that the modification group binds to the cellulose main chain via an amine salt (ionic bond).

<Other ingredients>
The curable resin composition according to the present invention may contain other components other than the essential components described above, such as commonly used additives, depending on the application. Other commonly used additives include, but are not limited to, resins and elastomers, inorganic fillers, curing catalysts, colorants, dispersants, defoaming agents/leveling agents, thixotropic agents, coupling agents, flame retardants, and the like. is mentioned. Moreover, the curable resin composition according to the present invention may contain an organic solvent or the like, if necessary.

(resin and elastomer)
Resins and elastomers are resin components other than the curable resins and curing agents described above, and include unsaturated polyester resins, acrylate resins, diallyl phthalate resins, silicone resins, norbornene-based resins, isocyanate resins, urethane resins, benzocyclobutene resins, Examples include polyazomethine resins, block copolymers, natural rubbers, diene rubbers, non-diene rubbers, thermoplastic elastomers, and the like.

(Inorganic filler)
Inorganic fillers include barium sulfate, barium titanate, amorphous silica, crystalline silica, fused silica, spherical silica, talc, clay, magnesium carbonate, calcium carbonate, aluminum oxide, aluminum hydroxide, alumina, silicon nitride, and boron nitride. , aluminum nitride and the like. These inorganic fillers can be used singly or in combination. Among these inorganic fillers, silica, especially spherical silica, is preferable because it has a small specific gravity, can be blended in a composition at a high proportion, and is excellent in low thermal expansion properties. The average particle size of the inorganic filler is preferably 3 μm or less, more preferably 1 μm or less. The average particle size of the inorganic filler can be determined using a laser diffraction particle size distribution analyzer.

The amount of the inorganic filler compounded is, for example, 25 to 90% by mass, preferably 30 to 90% by mass, more preferably 35 to 85% by mass, based on the solid content of the composition. By setting the blending amount of the inorganic filler within the above range, it is possible to ensure favorable coating performance of the cured product after curing.

(Curing catalyst)
Curing catalysts are mainly for curing thermosetting resins among curable resins. Imidazole derivatives such as phenylimidazole, 4-phenylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-(2-cyanoethyl)-2-ethyl-4-methylimidazole; dicyandiamide, benzyldimethylamine, 4-(dimethylamino) -N,N-dimethylbenzylamine, 4-methoxy-N,N-dimethylbenzylamine, 4-methyl-N,N-dimethylbenzylamine and other amine compounds; adipic acid dihydrazide, sebacate dihydrazide and other hydrazine compounds; Phosphorus compounds such as phenylphosphine, dimethylaminopyridine and the like. In addition, commercially available products include, for example, 2MZ-A, 2MZ-OK, 2PHZ, 2P4BHZ, 2P4MHZ (manufactured by Shikoku Chemical Industry Co., Ltd.), U-CAT3503N, U-CAT3502T, DBU, DBN, U-CATSA102, U- CAT5002 (manufactured by San-Apro Co., Ltd.), etc., may be used alone or in combination of two or more. Similarly, guanamine, acetoguanamine, benzoguanamine, melamine, 2,4-diamino-6-methacryloyloxyethyl-S-triazine, 2-vinyl-2,4-diamino-S-triazine, 2-vinyl-4,6 S-triazine derivatives such as -diamino-S-triazine/isocyanuric acid adduct and 2,4-diamino-6-methacryloyloxyethyl-S-triazine/isocyanuric acid adduct can also be used. These curing catalysts can be used alone or in combination.

From the viewpoint of transparency, the curing catalyst is preferably a phosphorus compound, particularly triphenylphosphine. Also, from the viewpoint of coating film properties, a basic catalyst is desirable. In particular, imidazoles are desirable, and by using imidazoles, both curability and stability of the composition can be achieved, and heat resistance can be improved.

The content of the curing catalyst is, for example, 0.01 to 20 parts by mass, preferably 0.05 to 15 parts by mass, more preferably 0.01 to 20 parts by mass, with respect to 100 parts by mass of the total thermosetting resin. It is 1 part by mass or more and 15 parts by mass or less.

(coloring agent)
Examples of the coloring agent include coloring pigments, dyes, and the like to which a Color Index (C.I.; published by The Society of Dyers and Colorists) number is assigned. For example, red colorants include monoazo, disazo, azo lake, benzimidazolone, perylene, diketopyrrolopyrrole, condensed azo, anthraquinone, and quinacridone colorants. Blue colorants include phthalocyanine-based, anthraquinone-based, and the like, and pigment-based compounds classified as pigments can be used. In addition to these, metal-substituted or unsubstituted phthalocyanine compounds can also be used. Green coloring agents include phthalocyanines, anthraquinones, and perylenes. In addition to these, metal-substituted or unsubstituted phthalocyanine compounds can also be used. Yellow colorants include monoazo, disazo, condensed azo, benzimidazolone, isoindolinone, and anthraquinone colorants. Examples of white colorants include rutile-type and anatase-type titanium oxide. Black colorants include carbon black, graphite, iron oxide, titanium black, iron oxide, anthraquinone, cobalt oxide, copper oxide, manganese, antimony oxide, nickel oxide, perylene, and aniline. Molybdenum sulfide, bismuth sulfide, etc. In addition, coloring agents such as purple, orange, and brown may be added for the purpose of adjusting the color tone.

The content of the coloring agent in the entire composition is, for example, 0.01% by mass or more and 3% by mass or less, preferably 0.05% by mass or more and 1% by mass or less, more preferably 0.1% by mass or more and 0.1% by mass or less. It is 5% by mass or less. Further, when obtaining a white cured film using titanium oxide or the like, the total composition contains, for example, 1% by mass or more and 65% by mass or less, preferably 3% by mass or more and 60% by mass or less, more preferably 5% by mass. % or more and 50 mass % or less.

(dispersant)
Dispersants include polycarboxylic acid, naphthalenesulfonic acid formalin condensation, polyethylene glycol, polycarboxylic acid partial alkyl ester, polyether, polyalkylenepolyamine, and other polymeric dispersants; alkylsulfonic acid; Low-molecular-weight dispersants such as higher ammonium, higher alcohol alkylene oxide, polyhydric alcohol ester, and alkyl polyamine can be used, and sufficient dispersing effect is obtained, and good coating properties of the cured product can be obtained. be able to.

(Antifoaming agent/leveling agent)
Compounds such as silicones, modified silicones, mineral oils, vegetable oils, fatty alcohols, fatty acids, metallic soaps, fatty acid amides, polyoxyalkylene glycols, polyoxyalkylene alkyl ethers, polyoxyalkylene fatty acid esters, etc. as antifoaming agents and leveling agents. etc. can be used, the generation of voids can be prevented, and the adhesion to the adherend is improved.

(thixotropic agent)
As the thixotropic agent, fine silica particles, silica gel, amorphous inorganic particles, polyamide additives, modified urea additives, wax additives, etc. can be used. The adhesion of the film to the adherend is excellent.

(coupling agent)
Coupling agents include alkoxy groups such as methoxy, ethoxy, and acetyl, and reactive functional groups such as vinyl, methacryl, acryl, epoxy, cyclic epoxy, mercapto, amino, diamino, acid anhydride, ureide, sulfide, vinyl silane compounds such as vinylethoxysilane, vinyltrimethoxysilane, vinyl-tris(β-methoxyethoxy)silane, γ-methacryloxypropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, etc., which are isocyanates, Amino silane compounds such as N-β-(aminoethyl)γ-aminopropyltrimethoxysilane, N-β-(aminoethyl)γ-aminopropylmethyldimethoxysilane, γ-ureidopropyltriethoxysilane, γ-glycides Epoxy silane compounds such as xypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and mercapto silanes such as γ-mercaptopropyltrimethoxysilane compounds, silane coupling agents such as phenylamino silane compounds such as N-phenyl-γ-aminopropyltrimethoxysilane, isopropyl triisostearoyl titanate, tetraoctylbis(ditridecylphosphite) titanate, bis(dioctylpyrophosphate ) oxyacetate titanate, isopropyltridodecylbenzenesulfonyltitanate, isopropyltris(dioctylpyrophosphate)titanate, tetraisopropylbis(dioctylphosphite)titanate, tetra(1,1-diallyloxymethyl-1-butyl)bis-(ditridecyl) Phosphite titanate, bis(dioctyl pyrophosphate) ethylene titanate, isopropyl trioctanoyl titanate, isopropyl dimethacryl isostearoyl titanate, isopropyl tristearoyl diacryl titanate, isopropyl tri(dioctyl phosphate) titanate, isopropyl tricumylphenyl titanate, dicumylphenyl Titanate coupling agents such as oxyacetate titanate and diisostearoyl ethylene titanate, ethylenically unsaturated zirconate-containing compounds, neoalkoxyzirconate-containing compounds, neoalkoxytris neodecanoyl zirconate, neoalkoxytris (dodecyl) benzenesulfonyl zirconate, neoalkoxytris(dioctyl)phosphate zirconate, neoalkoxytris(dioctyl)pyrophosphate zirconate, neoalkoxytris(ethylenediamino)ethylzirconate, neoalkoxytris(m-amino)phenylzirconate, tetra (2,2-diallyloxymethyl)butyl, di(ditridecyl)phosphitozirconate, neopentyl(diallyl)oxy, trineodecanoylzirconate, neopentyl(diallyl)oxy, tri(dodecyl)benzene-sulfonylzirconate, neopentyl (diallyl)oxy, tri(dioctyl)phosphatozirconate, neopentyl(diallyl)oxy, tri(dioctyl)pyro-phosphatozirconate, neopentyl(diallyl)oxy, tri(N-ethylenediamino)ethylzirconate, neopentyl ( diallyl)oxy, tri(m-amino)phenylzirconate, neopentyl(diallyl)oxy, trimethacrylzirconate, neopentyl(diallyl)oxy, triacrylzirconate, dineopentyl(diallyl)oxy, di-para-aminobenzoylzirconate, dineopentyl ( diallyl)oxy, di(3-mercapto)propionic zirconate, zirconium (IV) 2,2-bis(2-propenolatomethyl)butanolate, cyclodi[2,2-(bis-2-propenolatomethyl) Zirconate coupling agents such as butanolate]pyrophosphato-O, O, etc., aluminate coupling agents such as diisobutyl (oleyl) acetoacetylaluminate, alkylacetoacetate aluminum diisopropylate, etc. can be used, and adhesion to the substrate can be improved. can be expected to be improved and the hardness of the cured product can be improved.

(Flame retardants)
Flame retardants include hydrated metals such as aluminum hydroxide and magnesium hydroxide, red phosphorus, ammonium phosphate, ammonium carbonate, zinc borate, zinc stannate, molybdenum compounds, bromine compounds, chlorine compounds, and phosphate esters. , phosphorus-containing polyols, phosphorus-containing amines, melamine cyanurate, melamine compounds, triazine compounds, guanidine compounds, silicone polymers, etc. can be used, and the self-extinguishing property and heat resistance of the cured product can be achieved at a high level in a well-balanced manner.

(Organic solvent)
Examples of organic solvents include ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene, xylene and tetramethylbenzene; methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, and diethylene glycol. Glycol ethers such as monoethyl ether, dipropylene glycol monoethyl ether and triethylene glycol monoethyl ether; Esters such as ethyl acetate, butyl acetate, cellosolve acetate, diethylene glycol monoethyl ether acetate and esters of the above glycol ethers; alcohols such as ethanol, propanol, ethylene glycol and propylene glycol; amides such as dimethylformamide and dimethylacetamide; aliphatic hydrocarbons such as octane and decane; A petroleum solvent etc. can be mentioned.

The content of the organic solvent is not particularly limited, and can be appropriately adjusted according to the application of the curable resin composition.

In addition, such a curable resin composition is obtained by mixing and dispersing each raw material.

<<<Dry Film>>>
The dry film of the present invention is a resin layer obtained by coating or impregnating a substrate with the curable composition described above and drying the substrate.

Here, the substrate includes metal foil such as copper foil, film such as polyimide film, polyester film and polyethylene naphthalate (PEN) film, glass cloth, fiber such as aramid fiber.

A dry film is obtained, for example, by coating a curable composition on a polyethylene terephthalate film, drying it, and laminating a polypropylene film as necessary.

<<<cured product>>>
A cured product is obtained by curing the above-described curable composition (including the resin layer contained in the dry film).

The method for obtaining a cured product from the curable composition is not particularly limited, and can be changed as appropriate according to the composition of the curable composition. As an example, after performing the step of applying the curable composition onto the substrate as described above (for example, coating with an applicator or the like), a drying step of drying the curable composition is performed as necessary. Then, a thermosetting step of thermally cross-linking the curable resin and the curing agent by heating (for example, heating by an inert gas oven, a hot plate, a vacuum oven, a vacuum press, etc.) may be performed. The implementation conditions (for example, coating thickness, drying temperature and time, heating temperature and time, etc.) in each step may be appropriately changed according to the composition, application, etc. of the curable composition.

<<<Wiring board>>>
In the present invention, a wiring substrate can be produced using the dry film described above.

<<<Electronic Components>>>
Since such a cured product has excellent mechanical properties, heat resistance and transparency, it can be used for electronic parts and the like. In particular, it is used as a dry film for printed circuit boards, and as a sealant for light-emitting diodes for optical electronic parts.

<Preparation of oxidized pulp 1>
Eucalyptus-derived hardwood bleached kraft pulp (manufactured by CENIBRA) was used as the natural cellulose fiber. As TEMPO, a commercial product (manufactured by ALDRICH, Free radical, 98% by mass) was used. As sodium hypochlorite, a commercial product (manufactured by Wako Pure Chemical Industries, Ltd.) was used. As sodium bromide, a commercial product (manufactured by Wako Pure Chemical Industries, Ltd.) was used.

First, 100 g of bleached hardwood kraft pulp fiber is sufficiently stirred with 9900 g of ion-exchanged water, and then 1.25% by mass of TEMPO, 12.5% by mass of sodium bromide, and 28% by mass of sodium hypochlorite are added to 100 g of this pulp mass. .4% by weight were added in this order. Using a pH stud, the pH was maintained at 10.5 by dropwise addition of 0.5M sodium hydroxide. After the reaction was carried out for 120 minutes (20° C.), the dropwise addition of sodium hydroxide was stopped to obtain oxidized pulp. The obtained oxidized pulp was thoroughly washed with ion-exchanged water and then dehydrated to obtain oxidized pulp 1 having a solid content of 30.4% by mass.

<Preparation of fine cellulose fiber aqueous dispersion>
(Preparation Example 1)
105.3 g of oxidized pulp 1 was diluted with 1000 g of deionized water, and 346 g of concentrated hydrochloric acid was added to prepare a dispersion having an oxidized pulp solid content concentration of 2.34 wt % and a hydrochloric acid concentration of 2.5 M, followed by refluxing for 10 minutes. let me The obtained oxidized pulp was thoroughly washed to obtain an acid-hydrolyzed TEMPO oxidized pulp having a solid content of 41% by mass. After that, 0.88 g of oxidized pulp and 35.12 g of ion-exchanged water were subjected to a micronization treatment 10 times at 150 MPa using a high-pressure homogenizer to obtain a carboxyl group-containing fine cellulose fiber dispersion (solid concentration: 5.0% by mass). rice field. The fine cellulose fibers had an average fiber diameter of 11.0 nm, an average fiber length of 187 nm, an average aspect ratio of 17, and a carboxyl group content of 1.1 mmol/g.

<Preparation of fine cellulose fiber dispersion having modifying group>
(CNF1)
A beaker equipped with a magnetic stirrer and stirrer was charged with 40 g of the fine cellulose fibers obtained in Preparation Example 1 (solid concentration: 5.0% by mass). Subsequently, an amount of dodecylamine corresponding to 1.2 mol of amino groups per 1 mol of carboxyl groups of CNF, 0.34 g of 4-methylmorpholine, and 1.98 g of DMT-MM as a condensing agent were charged and dissolved in 300 g of DMF. let me The reaction solution was reacted at room temperature (25° C.) for 14 hours. After completion of the reaction, the mixture is filtered, washed with ethanol, DMT-MM salt is removed, washed with DMF, and the solvent is replaced to obtain a CNF/DMF dispersion in which an aliphatic hydrocarbon group is linked to CNF via an amide bond. got The solid content concentration of the obtained CNF/DMF dispersion was 2.2% by mass.

(CNF2)
A beaker equipped with a magnetic stirrer and stirrer was charged with 35 g of the fine cellulose fibers obtained in Preparation Example 1 (solid concentration: 5% by mass). Subsequently, tetrabutylammonium hydroxide was charged in an amount corresponding to 1 mol of amino group per 1 mol of carboxyl group of CNF, and dissolved in 300 g of DMF. The reaction solution was reacted at room temperature (25° C.) for 1 hour. After completion of the reaction, the reaction mixture was filtered and washed with DMF to obtain CNF in which an amine salt was bound to CNF. The obtained CNF/DMF dispersion had a solid content concentration of 4.0% by mass.

(CNF3)
10% by mass of fibrous fine cellulose powder (BiNFi-s manufactured by Sugino Machine, average fiber diameter 80 nm) is dehydrated and filtered, 10 times the amount of carbitol acetate is added to the filtered material, stirred for 30 minutes, and filtered. did. This replacement operation was repeated three times, and carbitol acetate was added in an amount 20 times the amount of the filter material to prepare a fine cellulose powder dispersion (solid concentration: 5.0% by mass).

<Preparation of curable resin composition>
According to the description in Table 1 below, after blending and stirring each component, a high-pressure homogenizer Nanovater NVL-ES008 manufactured by Yoshida Kikai Kogyo Co., Ltd. was used to repeat dispersion six times to prepare each composition. In addition, the numerical value in Table 1 shows the mass part of solid content (excluding a volatile component).

<Evaluation of film formability>
Each composition was applied to a PET film having a thickness of 38 μm using an applicator with a gap of 120 μm, and dried in a hot air circulating drying oven at 90° C. for 10 minutes to obtain a dry film having a resin layer of each composition. Thereafter, the resin layer of each composition was laminated by pressure bonding with a vacuum laminator at 60° C. and a pressure of 0.5 MPa for 60 seconds to a copper foil having a thickness of 18 μm, and the PET film was peeled off. Then, it was heated and cured at 180° C. for 30 minutes in a hot air circulating drying oven to obtain a copper foil sample having a cured film.
The surface condition of the resin layer after drying when the dry film was produced was visually observed. In addition, it was evaluated whether a self-supporting film (a film without defects) could be obtained when the cured film was peeled off from the copper foil sample provided with the cured film. Evaluation criteria are shown below. The results are also shown in Table 1.
○: The surface condition of the resin layer after drying is good, and the self-supporting film can be peeled off from the copper foil. The cured film is damaged when peeled off from the copper foil.

<Evaluation of transparency>
The dry film was pressure-bonded to a glass substrate having a thickness of 1 mm using a vacuum laminator at 60° C. and a pressure of 0.5 MPa for 60 seconds to laminate a resin layer of each composition, and the PET film was peeled off. Then, it was cured by heating at 180° C. for 30 minutes in a hot air circulating drying oven to obtain a sample for transparency evaluation. The obtained sample for transparency evaluation was placed in a visible light/ultraviolet light absorption measuring instrument (manufactured by JASCO Corporation: model V-570) to measure the transmittance of light with a wavelength of 450 nm. Evaluation criteria are shown below. The results are also shown in Table 1.
◎: transmittance of 85% or more ○: transmittance of 80% or more and less than 85% △: transmittance of 75% or more and less than 80% ×: transmittance of less than 75%

Epoxy resin 1: Celoxide 2021P (alicyclic epoxy resin) Epoxy resin 2 manufactured by Daicel Corporation: HP4032 (naphthalene type epoxy resin) Acid anhydride 1 manufactured by DIC Corporation: Rikashid MH700 Acid manufactured by Shin Nippon Rika Co., Ltd. Anhydride 2: Rikashid HH Shin Nippon Rika Co., Ltd. Phenol compound: HF4M (phenol novolac resin) Meiwa Kasei Co., Ltd. active ester compound: Bisphenol A diacetate Curing catalyst 1: Triphenylphosphine (TPP)
Curing catalyst 2: 2E4MZ (2-ethyl-4-methylimidazole) Shikoku Chemical Industry Co., Ltd.
Made

As described in detail above, by using a curable resin composition containing an epoxy resin, an acid anhydride, and CNF whose carboxyl group is modified with an amine compound, excellent film-forming properties and transparency can be obtained. It was confirmed that a cured product could be obtained.

Claims (8)

A curable resin composition comprising an epoxy resin, an acid anhydride, cellulose nanofibers, and a curing catalyst ,
The content of the acid anhydride is such that the acid anhydride equivalent/epoxy equivalent is 0.7 to 1.4,
The cellulose nanofibers include the structure of formula 1 below,
A curable resin composition , wherein the curing catalyst contains a phosphorus compound.
(Formula 1)

(R ₁ in Formula 1 is a saturated or unsaturated, cyclic, linear or branched hydrocarbon group, and R ₂ is hydrogen or a saturated or unsaturated, cyclic, linear or It is a branched hydrocarbon group.) 2. The curable resin composition according to claim ₁ , wherein R 1 is a hydrocarbon group having 3 to 18 carbon atoms, and R ₂ is hydrogen. 3. The curable resin composition according to claim 1, wherein said acid anhydride is an alicyclic compound. The curable resin composition according to any one of claims 1 to 3, wherein the epoxy resin is an alicyclic compound. A dry film comprising a resin layer obtained by coating or impregnating a film with the curable resin composition according to any one of claims 1 to 4, followed by drying. A cured product obtained by curing the curable resin composition according to any one of claims 1 to 4 or the resin layer of the dry film according to claim 5. A wiring board comprising the cured product according to claim 6 . An electronic component comprising the cured product according to claim 6 .