JP2020063394A - Curable resin composition, dry film, cured product and electronic component - Google Patents

Abstract

To provide a curable resin composition that is suitable for obtaining a cured product that, while maintaining low thermal expansion coefficients, has low elasticity, and is excellent in both of toughness (flexibility) and low water absorption, and a dry film, a cured product and an electronic component including the same.SOLUTION: The present invention provides a curable resin composition or the like containing an epoxy compound, an episulfide compound, a fine cellulose powder with at least one-dimension of it being smaller than 100 nm, and a filler other than the fine cellulose powder.SELECTED DRAWING: None

Description

  The present invention relates to a curable resin composition, a dry film, a cured product and an electronic component.

  As electronic devices are made smaller and lighter, the built-in printed wiring boards are required to have higher functionality and lighter weight. Therefore, the thickness of the copper clad laminate (so-called CCL), which is the base material of the printed wiring board, becomes thin, and the conductor layers and interlayer insulating layers (so-called build-up layers) formed on the copper clad laminate also have a high wiring density. Thinning is advancing along with the advancement and multi-layering.

Along with such thinning of the base material and the buildup layer, there is a problem that the obtained printed wiring board is apt to warp.
On the other hand, conventionally, a resin component is highly filled with an inorganic filler such as silica to reduce the thermal expansion coefficient (see Patent Document 1), or rubber or an elastomer is blended with the resin component to improve toughness (flexibility). A method (see Patent Document 2) has been proposed.

However, there is a problem that the toughness of the cured product is lowered by the method of highly filling the inorganic filler, while the thermal expansion coefficient and the water absorption rate of the cured product are increased by the method of adding the components such as rubber and elastomer.
That is, there is a demand for a curable resin composition that is effective for obtaining a cured product that has both excellent toughness (flexibility) and low water absorption while maintaining a low coefficient of thermal expansion due to high filling of an inorganic filler.

JP 2001-72834A JP, 2003-286391, A

Therefore, an object of the present invention is to provide a curable resin composition suitable for obtaining a cured product which has low elasticity and low toughness (flexibility) and low water absorption while maintaining a low coefficient of thermal expansion. Especially.
Another object of the present invention is to provide a dry film, a cured product and an electronic component using the above curable resin composition.

  The present inventor has made earnest studies toward the achievement of the above object. As a result, as a thermosetting resin, a combination of an epoxy compound and an episulfide compound is used, and fine cellulose having a dimension of at least one dimension smaller than 100 nm with respect to fillers such as silica, calcium carbonate, barium sulfate, talc, and titanium oxide. Surprisingly, they have found that the above problems can be solved by using powders in combination, and completed the present invention.

  That is, the curable resin composition of the present invention is characterized by containing an epoxy compound, an episulfide compound, a fine cellulose powder having at least one dimension smaller than 100 nm, and a filler other than the fine cellulose powder. It is a thing.

  The dry film of the present invention is characterized in that the curable resin composition has a resin layer formed by coating and drying the film on the film.

  The cured product of the present invention is characterized in that the curable resin composition or the resin layer of the dry film is cured.

  An electronic component of the present invention is characterized by including the cured product.

  Here, in the present invention, the shape of the fine cellulose powder is not particularly limited, and those having a shape such as a fibrous shape, a scaly shape, and a granular shape can be used, and "at least one dimension is smaller than 100 nm" , One-dimensional, two-dimensional or three-dimensional is smaller than 100 nm. For example, in the case of fibrous fine cellulose powder, those having a two-dimensional dimension smaller than 100 nm and having a spread in the remaining one dimension are mentioned, and in the case of scale-like fine cellulose powder, one side thereof is smaller than 100 nm. In the case of granular fine cellulose powder, those having a particle size of less than 100 nm in all three dimensions can be mentioned.

  Further, in the present invention, the one-dimensional, two-dimensional and three-dimensional sizes of the fine cellulose powder are the same as those of the fine cellulose powder by SEM (Scanning Electron Microscope; scanning electron microscope) and TEM (Transmission Electron Microscope; transmission electron microscope). ) Or AFM: Atomic Force Microscope; atomic force microscope) and the like.

  For example, in the case of scale-like fine cellulose powder, the average value of the thickness which is the smallest one dimension is measured, and this average thickness is set to be smaller than 100 nm. Specifically, a diagonal line of a micrograph is drawn, and 12 fine cellulose powders in the vicinity of which the thickness can be measured are randomly extracted to obtain the thickest fine cellulose powder and the thinnest fine cellulose powder. After removing the powder, the thickness of the remaining 10 points is measured, and the averaged value is smaller than 100 nm.

  In the case of fibrous fine cellulose powder, the average value of the fiber diameter which is the smallest two-dimensional (hereinafter, also simply referred to as “average fiber diameter”) is measured, and this average fiber diameter is set to be smaller than 100 nm. Specifically, a line is drawn on the diagonal line of the micrograph, and 12 fine cellulose powders in the vicinity thereof are randomly extracted to remove fine cellulose powders having the thickest fiber diameter and the thinnest fiber diameter. The fiber diameters of the remaining 10 points are measured, and the averaged value is smaller than 100 nm.

  In the case of granular fine cellulose powder, the average value of particle diameters is measured, and this average particle diameter is set to be smaller than 100 nm. Specifically, a line is drawn on the diagonal line of the micrograph, and 12 fine cellulose powders in the vicinity are randomly extracted to remove fine cellulose powders having the largest particle size and the smallest particle size. The particle size of the remaining 10 points is measured, and the averaged value is smaller than 100 nm.

  In the case of a fine cellulose powder having a fibrous or scale-like spread to other dimensions, the spread is, for example, less than 1000 nm, preferably less than 650 nm, more preferably less than 450 nm. When the spread is less than 1000 nm, the reinforcing effect due to the interaction between the fine cellulose powders can be effectively obtained.

  According to the present invention, it is possible to provide a curable resin composition that is effective in obtaining a cured product that is low in elasticity and has excellent toughness (flexibility) and low water absorption while maintaining a low thermal expansion coefficient. it can. Further, according to the present invention, it is possible to provide a dry film, a cured product and an electronic component using the above curable resin composition.

  Hereinafter, embodiments of the present invention will be described in detail.

  The curable resin composition of the present invention uses an epoxy compound and an episulfide compound in combination as a thermosetting resin, and uses a fine cellulose powder and a filler other than the fine cellulose powder in combination as a filler. The point has the greatest feature. With such a structure, the structure of the filler reduces the coefficient of thermal expansion while maintaining the toughness (flexibility), and the episulfide group is opened in the reaction between the episulfide compound and the epoxy compound. It is presumed that the resulting thiolate anion reacts with the epoxy group and introduces a thioether group into the crosslinked structure to impart low elasticity and excellent toughness (flexibility). Furthermore, although there was a problem that the water absorption rate is usually increased when the cellulose powder is blended, according to the configuration of the present invention, the surprising effect that the water absorption rate of the cured product is reduced results in the base material or the build. An interlayer insulating material suitable for thinning the up layer can be obtained.

[Epoxy compound]
The curable resin composition of the present invention contains an epoxy compound. The epoxy compound is not particularly limited and known compounds can be used. In particular, an epoxy compound having a plurality of epoxy groups in the molecule is preferable from the viewpoint of heat resistance and strength of the cured product, and an epoxy compound having two epoxy groups is more preferable from the viewpoint of toughness (flexibility).

  Examples of the epoxy compound include 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. Bisphenol type epoxy resin, bisphenol A novolac type epoxy resin, phenol novolac type epoxy resin, cresol novolac epoxy resin and other novolac type epoxy resin, biphenyl type epoxy resin, biphenylaralkyl type epoxy resin, aryl alkylene type epoxy resin, tetraphenylolethane Type epoxy resin, naphthalene type epoxy resin, anthracene type epoxy resin, phenoxy type epoxy resin, dicyclopentadiene Type epoxy resin, norbornene type epoxy resin, adamantane type epoxy resin, fluorene type epoxy resin, glycidyl methacrylate copolymer epoxy resin, cyclohexyl maleimide and glycidyl methacrylate copolymer epoxy resin, epoxy modified polybutadiene rubber derivative, CTBN modified Epoxy resin, trimethylolpropane polyglycidyl ether, phenyl-1,3-diglycidyl ether, biphenyl-4,4'-diglycidyl ether, 1,6-hexanediol diglycidyl ether, ethylene glycol or propylene glycol diglycidyl ether , Sorbitol polyglycidyl ether, tris (2,3-epoxypropyl) isocyanurate, triglycidyl tris (2-hydroxyethyl) Isocyanurate, phenoxy resins. Further, it may be an epoxy resin obtained by hydrogenating an epoxy resin having an aromatic ring such as a bisphenol type epoxy resin so as to be alicyclic. The epoxy compounds may be used alone or in combination of two or more.

[Episulfide compound]
The curable resin composition of the present invention contains an episulfide compound. The episulfide compound is not particularly limited and well-known compounds can be used. Particularly, an episulfide compound having a plurality of episulfide groups in the molecule is preferable, and an episulfide compound having two episulfide groups is more preferable from the viewpoint of toughness (flexibility).

  The method for synthesizing the episulfide compound is not particularly limited, and the episulfide compound may be synthesized from the epoxy compound using a sulfiding agent such as potassium thiocyanate or thiourea. Examples of the episulfide compound include an episulfide resin in which the epoxy group of each epoxy resin listed above as an epoxy compound is replaced with an episulfide group.

  The structure of the episulfide compound may be an episulfide compound having a cyclic skeleton such as an aromatic ring, a heterocycle, or an alicyclic structure, or an episulfide compound having an acyclic skeleton such as chain aliphatic, but is more tough ( An alicyclic skeleton or a chain aliphatic episulfide compound is preferable, and an episulfide compound having an alicyclic skeleton is more preferable because a cured product excellent in flexibility is obtained. Examples of the alicyclic skeleton include cycloalkane and cycloalkene, and among them, cycloalkane having 4 to 8 carbon atoms in the ring structure is preferable. Examples of the episulfide compound having an alicyclic skeleton include episulfide compounds obtained by changing the epoxy group of the epoxy compound having an alicyclic skeleton to an episulfide group among the epoxy compounds listed above as the epoxy compound. Specifically, hydrogenated bisphenol type episulfide resin, hydrogenated novolac type episulfide resin, hydrogenated biphenyl type episulfide resin, hydrogenated biphenylaralkyl type episulfide resin, hydrogenated arylalkylene type episulfide resin, hydrogenated tetraphenylolethane type episulfide. Resin etc. are mentioned. In the above, hydrogenation means adding hydrogen to reduce an aromatic ring (for example, a benzene ring) to form an aliphatic ring (for example, a cyclohexane ring). When it is referred to as “added bisphenol type” or the like, it suffices that it has a hydrogenated structure, that is, a structure in which an aromatic ring is substituted with an aliphatic ring, and is synthesized without hydrogenation. It may be. The episulfide compounds may be used alone or in combination of two or more.

  The blending amount of the episulfide compound is preferably 1 to 60 parts by mass, and more preferably 5 to 25 parts by mass with respect to 100 parts by mass of the nonvolatile component of the epoxy compound. By setting it as such a range, the hardened | cured material excellent in storage stability and flexibility can be obtained.

[Fine cellulose powder]
Attention was paid to fine cellulose powder as a powder having at least one dimension smaller than 100 nm, and when the relationship between the compounding amount and the coefficient of thermal expansion was diligently examined, it was found that a small amount of compounded cellulose powder It has been found that a significant reduction in the coefficient of thermal expansion can be obtained with the amount. Furthermore, focusing on the fact that the blending of the fine cellulose powder gives a sufficient effect of reducing the coefficient of thermal expansion even with a small amount of blending, and as a result of diligent studies, various requirements for insulating materials for electronic components such as toughness have been obtained. While blending a filler such as silica for ensuring the properties, by blending together with the fine cellulose powder, a cured product that can maintain a low coefficient of thermal expansion and is excellent in various properties such as toughness Is obtained. Further, by blending the fine cellulose powder, the molecular movement of the curable component in the composition is suppressed, and the storage stability becomes good.

  The fine cellulose powder used in the present invention is a powder having at least one dimension smaller than 100 nm, and as described above, it is not only fine spherical particles but also fibrous particles having a cross-sectional diameter smaller than 100 nm. And sheet-like (scale-like) particles having a thickness of less than 100 nm are also included. Such a fine cellulose powder has a much larger surface area per unit mass and an increased proportion of atoms exposed on the surface, as compared with one having a three-dimensional dimension of 100 nm or more. Therefore, it is considered that the reinforcing effect is exhibited by the interaction that the fine powders attract each other, and the thermal expansion property is lowered.

  The fine cellulose powder may be particles having at least one dimension smaller than 100 nm, and two or more particles having different shapes may be used in combination.

  It is preferable that such a fine cellulose powder is subjected to a hydrophobic treatment or a surface treatment using a coupling agent. For such treatment, a known and conventional method suitable for fine cellulose powder can be used.

  The compounding amount of the fine cellulose powder in the present invention is preferably 0.04 to 30% by mass, more preferably 0.08 to 20% by mass, and further preferably, to the total amount of the composition excluding the solvent. , 0.1 to 10% by mass. When the blending amount of the fine cellulose powder is 0.04% by mass or more, the effect of reducing the coefficient of thermal expansion can be satisfactorily obtained. On the other hand, when it is 30% by mass or less, the film forming property is improved.

  The fine cellulose powder according to the present invention can be obtained as follows, but is not limited to these.

  As the raw material of the fine cellulose powder, wood, hemp, bamboo, cotton, jute, kenaf, beet, agricultural waste products, pulp obtained from natural vegetable fiber raw materials such as cloth, regenerated cellulose fibers such as rayon and cellophane are used. In particular, pulp is preferable. The pulp, chemically or mechanically the plant raw material, or chemical pulp such as kraft pulp and sulfite pulp obtained by pulping using both, semi-chemical pulp, chemigrand pulp, chemi-mechanical pulp, Thermo-mechanical pulp, chemi-thermo-mechanical pulp, refiner mechanical pulp, ground wood pulp and deinked waste paper pulp containing these plant fibers as a main component, magazine waste paper pulp, corrugated cardboard waste paper pulp and the like can be used. Among them, various kraft pulps derived from softwood having a high fiber strength, such as unbleached kraft pulp of softwood, unbleached kraft pulp exposed to oxygen of softwood, and bleached kraft of softwood are particularly preferable.

  The raw material is mainly composed of cellulose, hemicellulose and lignin, and the content of lignin is usually about 0 to 40% by mass, and particularly about 0 to 10% by mass. If necessary, these raw materials may be lignin-removed or bleached to adjust the amount of lignin. The lignin content can be measured by the Klason method.

  In the cell wall of a plant, cellulose molecules are not a single molecule but regularly aggregate to form dozens of microfibrils (fine cellulose fibers) with crystallinity, which are the basic skeletal substances of plants. ing. Therefore, in order to produce a fine cellulose powder from the above raw materials, the above raw materials are beaten or pulverized, treated with high temperature and high pressure steam, treated with a phosphate or the like, and the cellulose fibers are oxidized using an N-oxyl compound as an oxidation catalyst. It is possible to use a method in which the fibers are unraveled to a nano size by performing a treatment or the like.

  Among the above, the beating or crushing treatment is a method in which a force is directly applied to the raw material such as the pulp to mechanically beat or crush and the fibers are loosened to obtain a fine cellulose powder. More specifically, for example, pulp or the like is mechanically treated with a high-pressure homogenizer or the like to disentangle cellulose fiber into a water suspension of about 0.1 to 3% by mass, which is loosened to a fiber diameter of about 0.1 to 10 μm. Further, a fine cellulose powder having a fiber diameter of about 10 to 100 nm can be obtained by repeatedly grinding or fusing it with a grinder or the like.

  The above grinding or crushing treatment can be carried out using, for example, a grinder "Pure Fine Mill" manufactured by Kurita Kikai Seisakusho. This grinder is a stone mill type crusher that crushes the raw material into ultrafine particles by the impact, centrifugal force and shearing force generated when the raw material passes through the gap between the upper and lower grinders. , Dispersion, emulsification and fibrillation can be carried out simultaneously. The above-mentioned grinding or crushing treatment can also be carried out using an ultrafine particle grinder "Supermass Colloider" manufactured by Masuyuki Sangyo Co., Ltd. The Super Mass Colloider is a grinder that enables ultrafine atomization that feels like it melts beyond the mere crushing range. The supermass colloider is a millstone type ultra-fine grain grinder composed of upper and lower non-porous grindstones whose spacing can be freely adjusted. The upper grindstone is fixed and the lower grindstone rotates at high speed. The raw material put into the hopper is fed into the gap between the upper and lower grindstones by centrifugal force, and due to the strong compression, shearing, and rolling frictional force generated there, the raw material is gradually ground and ultra-finely pulverized.

The high temperature and high pressure steam treatment is a method of obtaining fine cellulose powder by exposing the raw materials such as pulp to high temperature and high pressure steam to loosen the fibers.

  Further, the treatment with the phosphate or the like, by weakening the binding force between the cellulose fibers by making the surface of the raw material such as the pulp into a phosphoric acid ester, and then performing a refiner treatment to loosen the fibers and finely This is a processing method for obtaining a cellulose powder. For example, the above raw materials such as pulp are immersed in a solution containing 50% by mass of urea and 32% by mass of phosphoric acid, the solution is sufficiently impregnated between cellulose fibers at 60 ° C., and then heated at 180 ° C. After proceeding with phosphorylation and washing this with water, hydrolysis treatment is carried out in a 3% by mass hydrochloric acid aqueous solution at 60 ° C. for 2 hours, and then water washing is carried out again, and thereafter, in a 3% by mass aqueous sodium carbonate solution, Phosphorylation is completed by treating at room temperature for about 20 minutes, and the treated product is defibrated by a refiner to obtain a fine cellulose powder.

  Then, the treatment of oxidizing the cellulose fibers by using the N-oxyl compound as an oxidation catalyst is a method of obtaining fine cellulose powder by oxidizing the raw materials such as the pulp and then making them finer.

  First, an aqueous dispersion is prepared by dispersing natural cellulose fibers in water in an amount of about 10 to 1000 times (mass basis) on an absolute dry basis using a mixer or the like. The natural cellulose fibers as the raw material of the fine cellulose fibers, for example, wood pulp such as softwood pulp and hardwood pulp, non-wood pulp such as straw pulp and bagasse pulp, cotton pulp such as cotton lint and cotton linter, Bacterial cellulose etc. can be mentioned. These may be used alone or in appropriate combination of two or more. Further, these natural cellulose fibers may be previously subjected to treatment such as beating in order to increase the surface area.

  Next, in the above aqueous dispersion, the N-oxyl compound is used as an oxidation catalyst to oxidize the natural cellulose fiber. Examples of the N-oxyl compound include TEMPO (2,2,6,6-tetramethylpiperidine-N-oxyl), 4-carboxy-TEMPO, 4-acetamido-TEMPO, 4-amino-TEMPO, and 4-amino-TEMPO. -Dimethylamino-TEMPO, 4-phosphonooxy-TEMPO, 4-hydroxy TEMPO, 4-oxy TEMPO, 4-methoxy TEMPO, 4- (2-bromoacetamido) -TEMPO, 2-azaadamantane N-oxyl and the like, A TEMPO derivative having various functional groups at the C4 position can be used. As the amount of addition of these N-oxyl compounds, a catalytic amount is sufficient, and usually, it may be in the range of 0.1 to 10% by mass based on the absolute dry standard with respect to the natural cellulose fiber.

  In the oxidation treatment of the above natural cellulose fiber, an oxidizing agent and a co-oxidizing agent are used together. Examples of the oxidizing agent include halous acid, hypohalous acid and perhalogenic acid and salts thereof, hydrogen peroxide, perorganic acid, and among them, sodium hypochlorite and hypobromite Alkali metal hypohalites such as sodium are preferred. As the co-oxidant, for example, alkali metal bromide such as sodium bromide can be used. The amount of the oxidizing agent used is usually in the range of about 1 to 100% by mass on the basis of absolute dry weight with respect to the natural cellulose fiber, and the amount of the co-oxidizing agent is usually used on the basis of the absolute dry basis based on the natural cellulose fiber. Is in the range of about 1 to 30% by mass.

During the oxidation treatment of the natural cellulose fiber, it is preferable to maintain the pH of the aqueous dispersion within the range of 9 to 12 from the viewpoint of efficiently promoting the oxidation reaction. Further, the temperature of the aqueous dispersion during the oxidation treatment can be arbitrarily set within the range of 1 to 50 ° C., and the reaction can be performed at room temperature without temperature control. The reaction time can be in the range of 1 to 240 minutes. In addition, a penetrant may be added to the aqueous dispersion in order to permeate the drug to the inside of the natural cellulose fiber and introduce more carboxyl groups to the fiber surface. Examples of the penetrant include anionic surfactants such as carboxylates, sulfates, sulfonates and phosphates, and nonionic surfactants such as polyethylene glycol type and polyhydric alcohol type. .

  After the above-mentioned oxidation treatment of the natural cellulose fiber, it is preferable to carry out a purification treatment for removing impurities such as unreacted oxidizing agent and various by-products contained in the water dispersion liquid, prior to the micronization. Specifically, for example, a method of repeatedly washing and filtering the oxidized natural cellulose fiber with water can be used. The natural cellulose fiber obtained after the purification treatment is usually subjected to a refining treatment in a state where it is impregnated with an appropriate amount of water, but if necessary, it may be dried to obtain a fibrous or powdery form.

  Next, the miniaturization of the natural cellulose treatment is carried out in a state in which the natural cellulose fibers purified as desired are dispersed in a solvent such as water. The solvent as the dispersion medium used in the micronization treatment is generally preferably water, but if desired, alcohols (methanol, ethanol, isopropanol, isobutanol, sec-butanol, tert-butanol, methyl cellosolve, ethyl cellosolve, Ethylene glycol, glycerin, etc.), ethers (ethylene glycol dimethyl ether, 1,4-dioxane, tetrahydrofuran, etc.), ketones (acetone, methyl ethyl ketone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, etc.), etc. The water-soluble organic solvent may be used, or a mixture thereof may be used. The solid content concentration of the natural cellulose fiber in the dispersion liquid of these solvents is preferably 50% by mass or less. When the solid content concentration of the natural cellulose fiber exceeds 50% by mass, extremely high energy is required for dispersion, which is not preferable. For the miniaturization of natural cellulose treatment, low pressure homogenizer, high pressure homogenizer, grinder, cutter mill, ball mill, jet mill, beating machine, disintegrator, short axis extruder, twin screw extruder, ultrasonic stirrer, household juicer mixer, etc. It can be performed using a disperser.

  The fine cellulose powder obtained by the micronization treatment can be in the form of a suspension in which the solid content concentration is adjusted or a dried powder, as desired. Here, in the case of forming a suspension, only water may be used as the dispersion medium, and water and other organic solvents, for example, alcohols such as ethanol, surfactants, acids, bases, etc. A mixed solvent may be used.

  By the oxidation treatment and the micronization treatment of the natural cellulose fiber, the hydroxyl group at the C6 position of the constitutional unit of the cellulose molecule is selectively oxidized to a carboxyl group via the aldehyde group, and the content of the carboxyl group is 0.1. It is possible to obtain a highly crystalline fine cellulose powder having the above-mentioned predetermined number average fiber diameter, which is composed of cellulose molecules of 3 mmol / g. This highly crystalline fine cellulose powder has a cellulose type I crystal structure. This means that the fine cellulose powder is obtained by surface-oxidizing the naturally-derived cellulose molecules having the type I crystal structure to make them fine. In other words, natural cellulose fibers are made up of fine fibers called microfibrils produced in the process of biosynthesis, which are bundled together to form a high-order solid structure. (Hydrogen bond of) is weakened by introducing an aldehyde group or a carboxyl group by an oxidation treatment, and further subjected to a refining treatment to obtain a fine cellulose powder. By adjusting the conditions of the oxidation treatment, the content of the carboxyl group can be increased or decreased to change the polarity, or by the electrostatic repulsion of the carboxyl group or the refinement treatment, the average fiber diameter or average fiber length of the fine cellulose powder can be changed. , The average aspect ratio, etc. can be controlled.

The fact that the natural cellulose fiber has the I-type crystal structure is typical in two positions near 2θ = 14 to 17 ° and around 2θ = 22 to 23 ° in the diffraction profile obtained by measuring the wide-angle X-ray diffraction image. It can be identified by having a typical peak. In addition, the fact that a carboxyl group is introduced into the cellulose molecule of the fine cellulose powder means that absorption due to a carbonyl group (1608 cm ⁻ ) in a total reflection infrared spectroscopic spectrum (ATR) in a sample in which water is completely removed. It can be confirmed by the presence of (around ¹ ). In the case of a carboxyl group (COOH), absorption is present at 1730 cm ^-1 in the above measurement.

  Since halogen atoms are attached or bonded to the natural cellulose fiber after the oxidation treatment, dehalogenation treatment can be performed for the purpose of removing such residual halogen atoms. The dehalogenation treatment can be performed by immersing the natural cellulose fiber after the oxidation treatment in a hydrogen peroxide solution or an ozone solution.

  Specifically, for example, the natural cellulose fiber after the oxidation treatment is added to a hydrogen peroxide solution having a concentration of 0.1 to 100 g / L, with a bath ratio of about 1: 5 to 1: 100, preferably 1:10 to 1 : Dip under the condition of about 60 (mass ratio). The concentration of the hydrogen peroxide solution in this case is preferably 1 to 50 g / L, more preferably 5 to 20 g / L. The pH of the hydrogen peroxide solution is preferably 8 to 11, and more preferably 9.5 to 10.7.

In addition, the amount [mmol / g] of the carboxyl group in cellulose with respect to the mass of the fine cellulose powder contained in the aqueous dispersion can be evaluated by the following method. That is, 60 ml of a 0.5 to 1 mass% aqueous dispersion of a fine cellulose powder sample whose dry mass was precisely weighed in advance was prepared, and the pH was adjusted to about 2.5 with a 0.1 M hydrochloric acid aqueous solution, and then 0.05 M. The aqueous sodium hydroxide solution is added dropwise until the pH reaches about 11, and the electrical conductivity is measured. The amount of functional groups can be determined from the amount (V) of sodium hydroxide consumed in the step of neutralizing a weak acid whose electric conductivity changes slowly, using the following formula. This amount of functional groups indicates the amount of carboxyl groups.
Functional group amount [mmol / g] = V [ml] × 0.05 / fine cellulose powder sample [g]

In addition, the fine cellulose powder used in the present invention may be chemically and / or physically modified to have enhanced functionality. Here, as the chemical modification, a functional group is added by acetalization, acetylation, cyanoethylation, etherification, isocyanation or the like, or an inorganic substance such as silicate or titanate is compounded by a chemical reaction or a sol-gel method, Alternatively, it can be coated. Examples of the method of chemical modification include a method of immersing a sheet-shaped fine cellulose powder in acetic anhydride and heating it. In addition, the fine cellulose powder obtained by the treatment of oxidizing cellulose fibers by using an N-oxyl compound as an oxidation catalyst has a carboxyl group in the molecule modified with an amine compound or a quaternary ammonium compound by an ionic bond or an amide bond. There is a method of making it.
As a method of physical modification, for example, a metal or ceramic raw material is subjected to physical vapor deposition (PVD method) such as vacuum vapor deposition, ion plating, sputtering, chemical vapor deposition (CVD method), electroless plating or electrolytic plating. A method of coating is exemplified by a method. These modifications may be performed before or after the above treatment.

  When the fine cellulose powder used in the present invention is fibrous, the average fiber diameter thereof is preferably 3 nm or more and smaller than 100 nm. Since the minimum diameter of the fine cellulose fiber monofilament is 3 nm, it is practically impossible to produce particles having a diameter of less than 3 nm. On the other hand, when the thickness is less than 100 nm, the desired effect of the present invention can be obtained without adding excessively, and the film-forming property becomes good. The number average fiber diameter of the fine cellulose powder can be measured according to the method for measuring the size of the fine cellulose powder described above.

[Filler other than fine cellulose powder]
The curable resin composition of the present invention further contains a filler other than the above-mentioned fine cellulose powder. Examples of such fillers include barium sulfate, barium titanate, amorphous silica, crystalline silica, fused silica, spherical silica, talc, clay, magnesium carbonate, calcium carbonate, aluminum oxide, aluminum hydroxide, silicon nitride, aluminum nitride. Inorganic fillers such as titanium oxide. Among the fillers, silica is preferable. The fillers other than the fine cellulose powder may be used alone or in combination of two or more.

  The average particle size of the filler is preferably 3 μm or less, more preferably 1 μm or less. The average particle size of the filler can be determined by a laser diffraction particle size distribution measuring device.

  The blending amount of this filler is 1 to 90% by mass, preferably 2 to 80% by mass, and more preferably 5 to 75% by mass, based on the total amount of the composition excluding the solvent. By setting the blending amount of the filler within the above range, it is possible to ensure good coating film performance of the cured product after curing.

The compounding ratio of the filler other than the fine cellulose powder and the fine cellulose powder in all the fillers is a mass ratio (filler other than fine cellulose powder: fine cellulose powder) = 100: (0.04 to 30), preferably Is 100: (0.1-20), more preferably 100: (0.2-10). By using the filler in such a blending ratio, it is possible to satisfy various characteristics such as toughness required for the insulating material of the electronic component while maintaining a low coefficient of thermal expansion.
Further, the total amount of fillers mixed in the curable resin composition is appropriately known in accordance with the use of the curable resin composition, for example, required characteristics of an insulating material such as an interlayer insulating material of an electronic component. The amount is preferable.

(Curing agent)
The curable resin composition of the present invention may contain a curing agent. As the curing agent, a compound having a phenolic hydroxyl group, a polycarboxylic acid and an acid anhydride thereof, a compound having a cyanate ester group, a compound having an active ester group capped with a hydroxyl group such as acetylation, a carboxyl group in the side chain or Examples thereof include a curing agent having a hydroxyl group, a carboxyl group, and an active ester structure, which reacts with the epoxy group or episulfide group of the epoxy compound or episulfide compound described above, such as a cycloolefin polymer having a hydroxyl group or an active ester structure. As the curing agent, one type may be used alone, or two or more types may be used in combination.

  Examples of the compound having a phenolic hydroxyl group include phenol novolac resin, alkylphenol volac resin, bisphenol A novolac resin, dicyclopentadiene type phenol resin, Xylok type phenol resin, terpene modified phenol resin, cresol / naphthol resin, polyvinylphenol, Conventionally known compounds such as phenol / naphthol resin, α-naphthol skeleton-containing phenol resin and triazine-containing cresol novolac resin can be used.

  The above-mentioned polycarboxylic acid and its acid anhydride are compounds having two or more carboxyl groups in one molecule and their acid anhydrides, for example, (meth) acrylic acid copolymers and maleic anhydride copolymers. In addition to dibasic acid condensates and the like, resins having a carboxylic acid terminal such as a carboxylic acid terminal imide resin can be mentioned.

  The above-mentioned compound having a cyanate ester group is a compound having two or more cyanate ester groups (-OCN) in one molecule. As the compound having a cyanate ester group, any conventionally known compound can be used. Examples of the compound having a cyanate ester group include phenol novolac type cyanate ester resin, alkylphenol novolac type cyanate ester resin, dicyclopentadiene type cyanate ester resin, bisphenol A type cyanate ester resin, bisphenol F type cyanate ester resin, bisphenol S type. Cyanate ester resins are mentioned. Further, it may be a prepolymer in which a part is triazine.

The compound having an active ester group is not particularly limited, and a resin having two or more active ester groups in one molecule is preferable. The active ester resin can be generally obtained by a condensation reaction of one or more of a carboxylic acid compound and a thiocarboxylic acid compound and one or more of a hydroxy compound and a thiol compound. Examples of the compound having an active ester group include a dicyclopentadienyl diphenol ester compound, bisphenol A diacetate, diphenyl phthalate, diphenyl terephthalate, and bis [4- (methoxycarbonyl) phenyl] terephthalate.
The compound having an active ester group is suitable for reducing the relative dielectric constant and the dielectric loss tangent and obtaining an electronic component having low dielectric properties.

  Such a curing agent is appropriately mixed with a known composition depending on the use of the curable resin composition containing them as a constituent, for example, required characteristics of an insulating material such as an interlayer insulating material of an electronic component. It is preferable. Among them, it is particularly preferable to use a compound having a phenolic hydroxyl group from the viewpoint of toughness (flexibility) and a compound having an active ester group from the viewpoint of low water absorption.

  The compounding amount of the curing agent is preferably 0.5 to 2.5 mol, and the functional group number of the curing agent to react is 0.7 to 0.7 mol per 1 mol of the total of the epoxy group and the episulfide group of the epoxy compound and the episulfide compound in the composition. It is more preferably about 1.5 mol. When it is 0.5 mol or more, the toughness (flexibility) of the cured product is excellent. When it is 2.5 mol or less, low water absorption, storage stability are improved, and thermal expansion coefficient is suppressed.

(Curing accelerator)
The curable resin composition of the present invention may contain a curing accelerator. As the curing accelerator, for example, imidazole, 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 4-phenylimidazole, 1-cyanoethyl-2-phenylimidazole, 1- Imidazole derivatives such as (2-cyanoethyl) -2-ethyl-4-methylimidazole; dicyandiamide, benzyldimethylamine, 4- (dimethylamino) -N, N-dimethylbenzylamine, 4-methoxy-N, N-dimethylbenzyl. Amines, amine compounds such as 4-methyl-N, N-dimethylbenzylamine, hydrazine compounds such as adipic acid dihydrazide and sebacic acid dihydrazide; phosphorus compounds such as triphenylphosphine, guanamine, acetoguanamine, benzoguanamine, and Min, 2,4-diamino-6-methacryloyloxyethyl-S-triazine, 2-vinyl-2,4-diamino-S-triazine, 2-vinyl-4,6-diamino-S-triazine / isocyanuric acid adduct , S-triazine derivatives such as 2,4-diamino-6-methacryloyloxyethyl-S-triazine / isocyanuric acid adduct, and the like. The curing accelerators may be used alone or in combination of two or more.

  The compounding amount of the curing accelerator is preferably 0.1 to 10 parts by mass, and 0.3 to 7 parts by mass with respect to 100 parts by mass of the total amount of the non-volatile components of the epoxy compound and the episulfide compound in the composition. More preferably. By setting the blending amount within the above range, it is possible to obtain a composition in which curability and storage stability are balanced.

  The curable resin composition of the present invention may contain a curable resin other than the epoxy compound and the episulfide compound as long as the effects of the present invention are not impaired. As the thermosetting resin other than the epoxy compound and the episulfide compound, any resin may be used as long as it is a resin that is cured by heating and exhibits electrical insulation, a compound having a cyclic ether group such as an oxetane compound, a melamine resin, a silicone resin, a benzoguanamine resin, Known resins such as amino resins such as melamine derivatives and benzoguanamine derivatives, polyisocyanate compounds, blocked isocyanate compounds, cyclocarbonate compounds, episulfide resins, bismaleimide, carbodiimide resins, polyimide resins, polyamideimide resins, polyphenylene ether resins, polyphenylene sulfide resins, etc. A curable resin can be used.

  Further, a photocurable resin may be blended to impart photocurability. The photocurable resin may be any resin that is curable by light irradiation, and examples thereof include alkyl (meth) acrylates such as 2-ethylhexyl (meth) acrylate and cyclohexyl (meth) acrylate; 2-hydroxyethyl (meth ) Hydroxyalkyl (meth) acrylates such as acrylate and 2-hydroxypropyl (meth) acrylate; mono- or di (meth) acrylates of alkylene oxide derivatives such as ethylene glycol, propylene glycol, diethylene glycol and dipropylene glycol; hexanediol, Polyhydric alcohols such as trimethylolpropane, pentaerythritol, ditrimethylolpropane, dipentaerythritol, and trishydroxyethyl isocyanurate or their ethylene oxides. Or poly (meth) acrylates of propylene oxide adducts; (meth) acrylates of phenolic ethylene oxide or propylene oxide adducts such as phenoxyethyl (meth) acrylate and polyethoxydi (meth) acrylate of bisphenol A; glycerin di (Meth) acrylates of glycidyl ethers such as glycidyl ether, trimethylolpropane triglycidyl ether, and triglycidyl isocyanurate; and melamine (meth) acrylate.

  The photocurable resin is used together with a photoreaction initiator that generates any one of a radical, a base and an acid, if necessary. Examples of the photoreaction initiator include bis- (2,6-dichlorobenzoyl) phenylphosphine oxide, bis- (2,6-dichlorobenzoyl) -2,5-dimethylphenylphosphine oxide, and bis- (2 , 6-Dichlorobenzoyl) -4-propylphenylphosphine oxide, bis- (2,6-dichlorobenzoyl) -1-naphthylphosphine oxide, bis- (2,6-dimethoxybenzoyl) phenylphosphine oxide, bis- (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, bis- (2,6-dimethoxybenzoyl) -2,5-dimethylphenylphosphine oxide, bis- (2,4,6) -Trimethylbenzoyl) -phenylphosphine oxa (BASF Japan Ltd., IRGACURE819) and other bisacylphosphine oxides; 2,6-dimethoxybenzoyldiphenylphosphine oxide, 2,6-dichlorobenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoyl. Phenylphosphinic acid methyl ester, 2-methylbenzoyldiphenylphosphine oxide, pivaloylphenylphosphinic acid isopropyl ester, 2,4,6-trimethylbenzoyldiphenylphosphine oxide (BASF Japan Ltd., DAROCUR TPO), etc. Monoacylphosphine oxides; 1-hydroxy-cyclohexyl phenyl ketone, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2- Methyl-1-propan-1-one, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] phenyl} -2-methyl-propan-1-one, 2 Hydroxyacetophenones such as -hydroxy-2-methyl-1-phenylpropan-1-one; benzoin such as benzoin, benzyl, benzoin methyl ether, benzoin ethyl ether, benzoin n-propyl ether, benzoin isopropyl ether, benzoin n-butyl ether Benzoin alkyl ethers; benzophenones such as benzophenone, p-methylbenzophenone, Michler's ketone, methylbenzophenone, 4,4'-dichlorobenzophenone, 4,4'-bisdiethylaminobenzophenone; acetophenone, 2 2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2 Acetophenones such as -morpholino-1-propanone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1, N, N-dimethylaminoacetophenone; thioxanthone, 2-ethylthioxanthone, 2 -Thioxanthones such as isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, and 2,4-diisopropylthioxanthone; anthraquinone, chloroanthraquinone, 2-methylan Anthraquinones such as raquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone, 2-amylanthraquinone and 2-aminoanthraquinone; ketals such as acetophenone dimethyl ketal and benzyldimethyl ketal; ethyl-4-dimethyl Benzoic acid esters such as aminobenzoate, 2- (dimethylamino) ethylbenzoate, p-dimethylbenzoic acid ethyl ester; 1.2-octanedione, 1- [4- (phenylthio)-, 2- (O-benzoyloxime )], Ethanone, oxime esters such as 1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl]-, 1- (0-acetyloxime); bis (η5-2 , 4-Cyclopentadiene-1-yl)- Sus (2,6-difluoro-3- (1H-pyrrol-1-yl) phenyl) titanium, bis (cyclopentadienyl) -bis [2,6-difluoro-3- (2- (1-pyr-1 Examples include titanocene such as -yl) ethyl) phenyl] titanium; phenyldisulfide 2-nitrofluorene, butyroin, anisoin ethyl ether, azobisisobutyronitrile, tetramethylthiuram disulfide and the like. One of the above photoreaction initiators may be used alone, or two or more thereof may be used in combination.

  Such a photocurable resin and a photoreaction initiator are appropriately and commonly used depending on the use of the photocurable resin composition containing them as a constituent component, for example, the required characteristics of an insulating material such as an interlayer insulating material of an electronic component. It is preferable to use a known composition.

  When the curable resin composition of the present invention is used as an alkali-developable photosolder resist composition that can be developed with an alkaline aqueous solution, a carboxyl group-containing resin is used in addition to the above-mentioned photocurable resin. It is preferable.

As the carboxyl group-containing resin, both a photosensitive carboxyl group-containing resin having at least one photosensitive unsaturated double bond and a carboxyl group-containing resin having no photosensitive unsaturated double bond can be used. And is not limited to a particular one. As the carboxyl group-containing resin, the resins listed below can be particularly preferably used.
(1) A carboxyl group-containing resin obtained by copolymerizing an unsaturated carboxylic acid and a compound having an unsaturated double bond, and a carboxyl group-containing resin obtained by modifying the resin to adjust its molecular weight and acid value.
(2) A photosensitive carboxyl group-containing resin obtained by reacting a carboxyl group-containing (meth) acrylic copolymer resin with a compound having an oxirane ring and an ethylenically unsaturated group in one molecule.
(3) An unsaturated monocarboxylic acid is reacted with a copolymer of a compound having one epoxy group and a compound having an unsaturated double bond in one molecule and a compound having an unsaturated double bond, and produced by this reaction. A photosensitive carboxyl group-containing resin obtained by reacting the secondary hydroxyl group with a saturated or unsaturated polybasic acid anhydride.
(4) After reacting the hydroxyl group-containing polymer with a saturated or unsaturated polybasic acid anhydride, the carboxylic acid produced by this reaction is treated with a compound having one epoxy group and one unsaturated double bond in each molecule. A photosensitive hydroxyl- and carboxyl-containing resin obtained by the reaction.
(5) Photosensitive carboxyl group obtained by reacting a polyfunctional epoxy compound with an unsaturated monocarboxylic acid, and reacting a part or all of the secondary hydroxyl group generated by this reaction with a polybasic acid anhydride Containing resin.
(6) A polyfunctional epoxy compound is reacted with a compound having two or more hydroxyl groups in one molecule and one reactive group other than a hydroxyl group that reacts with an epoxy group, and an unsaturated group-containing monocarboxylic acid to obtain A carboxyl group-containing photosensitive resin obtained by reacting the obtained reaction product with a polybasic acid anhydride.
(7) Obtained by reacting a reaction product of a resin having a phenolic hydroxyl group with an alkylene oxide or a cyclic carbonate with an unsaturated group-containing monocarboxylic acid, and reacting the obtained reaction product with a polybasic acid anhydride. Carboxyl group-containing photosensitive resin.
(8) Reaction product obtained by reacting a polyfunctional epoxy compound with a compound having at least one alcoholic hydroxyl group and one phenolic hydroxyl group in one molecule and an unsaturated group-containing monocarboxylic acid A carboxyl group-containing photosensitive resin obtained by reacting the alcoholic hydroxyl group of the above with an anhydride group of a polybasic acid anhydride.

  The carboxyl group-containing resin is preferably blended in a known composition which is commonly used in an alkali developing type curable resin composition such as a solder resist composition containing the resin as a constituent.

  The curable resin composition of the present invention may further contain other conventional compounding ingredients as appropriate depending on the application. Other commonly used compounding ingredients include thermoplastic resins, elastomers, polymer resins such as rubber particles, sensitizers, flame retardants, coloring agents, diluents such as organic solvents, and other additives, specifically Examples include known and commonly used additives such as foaming agents / leveling agents, thixotropy-imparting agents / thickening agents, coupling agents, and dispersants.

  Examples of the organic solvent 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, 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 esterification products of the above glycol ethers; Alcohols such as ethanol, propanol, ethylene glycol, propylene glycol; octa Aliphatic hydrocarbons such as decane may be mentioned petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, a petroleum solvent or the like, such as solvent naphtha. As the organic solvent, one type may be used alone, or two or more types may be used in combination.

  The curable resin composition of the present invention containing the components described above may be formed into a dry film or used as a liquid as it is. When used as a liquid, it may be a one-pack type or a two-pack type or more. Further, the curable resin composition of the present invention can also be used as a so-called prepreg obtained by coating or impregnating a sheet-like fibrous base material such as a glass cloth, a nonwoven fabric of glass and aramid, and semi-curing.

The dry film of the present invention has a resin layer obtained by coating and drying the curable resin composition of the present invention on a film (supporting film).
Here, when forming a dry film, first, after diluting the curable resin composition of the present invention with the above organic solvent to an appropriate viscosity, a comma coater, a blade coater, a lip coater, a rod coater A squeeze coater, a reverse coater, a transfer roll coater, a gravure coater, a spray coater or the like is used to apply a uniform thickness on the film. Then, the applied composition is usually dried at a temperature of 40 to 130 ° C. for 1 to 30 minutes to form a resin layer. The coating film thickness is not particularly limited, but in general, the film thickness after drying is appropriately selected within the range of 3 to 150 μm, preferably 5 to 60 μm.

  As the film (supporting film), a resin film is used, and for example, a polyester film such as polyethylene terephthalate (PET), a polyimide film, a polyamideimide film, a polypropylene film, a polystyrene film or the like can be used. The thickness of this film is not particularly limited, but generally, it is appropriately selected within the range of 10 to 150 μm. More preferably, it is in the range of 15 to 130 μm.

Thus, with respect to the film having the resin layer formed of the curable resin composition of the present invention formed thereon, a peelable film (for example, to prevent dust from adhering to the surface of the resin layer) It is preferable to further laminate a protective film).
The peelable film may be one that has a smaller adhesive force with the resin layer than the adhesive force between the resin layer and the supporting film when peeling, and examples thereof include a polyethylene film, a polytetrafluoroethylene film, and a polypropylene film. Alternatively, surface-treated paper or the like can be used.

  In the present invention, the curable resin composition of the present invention may be applied on the protective film and dried to form a resin layer, and a support film may be laminated on the surface of the resin layer. That is, as the film to which the curable resin composition of the present invention is applied when producing the dry film in the present invention, either a support film or a protective film may be used.

  The cured product of the present invention is obtained by curing the curable resin composition of the present invention or the resin layer of the dry film of the present invention. Such a cured product of the present invention can be suitably used as an electronic component material such as a solder resist, an interlayer insulating material, or a filling material, which requires insulation reliability.

  The electronic component of the present invention comprises the above-mentioned cured product of the present invention, and specific examples thereof include a printed wiring board. In particular, a multilayer printed wiring board using the curable resin composition of the present invention as an interlayer insulating material can have good interlayer insulation reliability.

Hereinafter, the present invention will be described in more detail with reference to examples.
[Preparation of dispersion liquid of fibrous fine cellulose powder]
Bleached kraft pulp fibers of coniferous trees (Menchen CSF 650 ml manufactured by Fletcher Challenge Canada, Inc.) were sufficiently stirred with 9900 g of ion-exchanged water, and then TEMPO (2,2,6,6-tetramethyl manufactured by ALDRICH was added to 100 g of the pulp mass. Piperidine 1-oxyl free radical) 1.25% by mass, sodium bromide 12.5% by mass, and sodium hypochlorite 28.4% by mass were added in this order. A pH stud was used to maintain the pH at 10.5 by dropwise addition of 0.5M sodium hydroxide. After the reaction was carried out for 120 minutes (20 ° C.), the dropping of sodium hydroxide was stopped to obtain oxidized pulp. The resulting oxidized pulp was thoroughly washed with ion-exchanged water, and then dehydrated. Thereafter, 3.9 g of oxidized pulp and 296.1 g of ion-exchanged water were subjected to a micronization treatment twice at 245 MPa using a high-pressure homogenizer (Starburst Lab HJP-2 5005 manufactured by Sugino Machine Ltd.), and a carboxyl group-containing fine cellulose powder. A body dispersion (solid content concentration 1.3% by mass) was obtained.

  Next, 408.75 g of the dispersion liquid of the obtained carboxyl group-containing fine cellulose powder was placed in a beaker, and 4085 g of ion-exchanged water was added to prepare a 0.5% by mass aqueous solution, which was heated at room temperature (25 ° C.) with a mechanical stirrer, Stir for 30 minutes. Subsequently, 245 g of a 1 M hydrochloric acid aqueous solution was charged and reacted at room temperature for 1 hour. After completion of the reaction, the precipitate was reprecipitated with acetone, filtered, and then washed with acetone / ion-exchanged water to remove hydrochloric acid and salts. Finally, acetone was added and filtered to obtain a dispersion liquid (solid content concentration 5.0% by mass) of the acetone-containing acid type cellulose powder in a state where the carboxyl group-containing fine cellulose powder was swollen in acetone. After the completion of the reaction, the mixture was filtered and then washed with ion-exchanged water to remove hydrochloric acid and salts. After the solvent substitution with acetone, the solvent substitution with DMF was performed, and the dispersion liquid of the DMF-containing acid-type cellulose powder in a state where the carboxyl group-containing fine cellulose powder was swollen (average fiber diameter: 3.3 nm, solid content concentration: 5.0 mass) %) Was obtained.

  Further, 40 g of the DMF-containing acid-type cellulose powder dispersion and 0.3 g of hexylamine were placed in a beaker equipped with a magnetic stirrer and a stirrer and dissolved with 300 g of ethanol. The reaction solution was reacted at room temperature (25 ° C) for 6 hours. After completion of the reaction, filtration, washing with DMF, and solvent substitution were performed to obtain a dispersion liquid (solid content concentration: 5.0% by mass) of fine cellulose powder in which amine was linked to fine cellulose powder through an ionic bond. .

(Examples 1 to 7, Comparative Examples 1 to 4)
After blending and stirring each component according to the description in Table 1 below, a high pressure homogenizer Nanowater NVL-ES008 manufactured by Yoshida Kikai Kogyo Co., Ltd. was used and dispersed 6 times to prepare each composition. In addition, the numerical value in Table 1 shows the mass part in a non-volatile component.

  With respect to each composition obtained in Examples and Comparative Examples, cured products were evaluated for thermal expansion property, toughness (flexibility), water absorption and elasticity. The evaluation method is as follows.

[Thermal expansion]
Each composition was applied to a PET film having a thickness of 38 μm with an applicator having a gap of 120 μm and dried at 90 ° C. for 10 minutes in a hot air circulation type drying oven to obtain a dry film having a resin layer of each composition. Then, it was pressure-bonded to a copper foil having a thickness of 18 μm under the conditions of 60 ° C. and a pressure of 0.5 MPa for 60 seconds with a vacuum laminator to laminate a resin layer of each composition, and the PET film was peeled off. Then, it was heated in a hot air circulation type drying oven at 180 ° C. for 30 minutes to be cured, and peeled from the copper foil to obtain a film sample made of a cured product of each composition. The obtained film sample was cut into a piece having a width of 3 mm and a length of 30 mm to obtain a test piece for thermal expansion evaluation. About this test piece, using TMA (Thermo-mechanical Analysis) Q400 manufactured by TA Instruments Co., Ltd., in a tensile mode, 16 mm between chucks, a load of 30 mN, and a temperature of 20 ° C. to 250 ° C. were increased at 5 ° C./min. Then, the temperature was lowered to 250 to 20 ° C. at 5 ° C./min, and the thermal expansion coefficients α1 and α2 (ppm / K) were measured and evaluated. The results of these measurements are also shown in Table 1.

[Toughness (flexibility) and elasticity]
A film sample made of a cured product of each composition prepared by the same method as described above was cut into a piece having a width of 5 mm and a length of 70 mm to obtain a test piece for toughness (flexibility) evaluation and elasticity evaluation.
(Toughness (flexibility))
For this test piece, an EZ-SX manufactured by Shimadzu Corporation was used to perform a tensile test, the distance between the grips was 50 mm, the pulling speed was 1 mm / min, the measurement was performed 10 times, and the elongation rate until the test piece broke was measured. The toughness (flexibility) was evaluated by setting the maximum value as the tensile elongation at break (%). The evaluation criteria are as follows. The evaluation results are also shown in Table 1.
◎: 3.0% or more ○: 2.5% or more and less than 3.0% △: 2.0% or more and less than 2.5% ×: Less than 2.0% (elasticity)
This test piece was subjected to the same test as the above-mentioned toughness (flexibility) evaluation, the elastic modulus at a tensile strength of 5 to 10 MPa was measured, and the average value thereof was used as the elastic modulus (GPa) to evaluate the elasticity. The evaluation criteria are as follows. The evaluation results are also shown in Table 1.
⊚: Less than 6.5 GPa ○: 6.5 GPa or more and less than 7.0 GPa △: 7.0 GPa or more and less than 7.5 GPa ×: 7.5 GPa or more

◎：０．３％未満のもの
〇：０．３％以上０．６％未満のもの
△：０．６％以上１．０％未満のもの
×：１．０％以上のもの [Water absorption]
A film sample made of a cured product of the composition produced by the same method as described above was cut into 100 mm × 100 mm to obtain a water absorption evaluation test piece. This test piece was dried at 105 ° C. for 1 hour, and the weight of the dried test piece was measured with a precision balance. Then, the dried test piece was allowed to stand in water at 23.5 ° C. for 24 hours to absorb water. After taking out the water-absorbed test piece from water, the water on the surface of the sample was wiped off and the weight after water absorption was measured by a precision balance. The water absorption rate was calculated from the weight change of the dried test piece and the water-absorbed test piece to evaluate the water absorption. The evaluation criteria are as follows. The evaluation results are also shown in Table 1.

◎: Less than 0.3% 〇: 0.3% or more and less than 0.6% △: 0.6% or more and less than 1.0% ×: 1.0% or more

* 1: jER828 (manufactured by Mitsubishi Chemical Corporation, bisphenol A type epoxy resin, epoxy group equivalent 189 g / eq.)
* 2: HP4032 (DIC Corporation, epoxy resin having a naphthalene skeleton, epoxy group equivalent 150 g / eq.)
* 3: TBIS-AHS (Taoka Chemical Co., Ltd., episulfide resin having an alicyclic skeleton, episulfide group equivalent 192 g / eq.)
* 4: TBIS-FXPS (Taoka Chemical Co., Ltd., aromatic ring-containing episulfide resin, episulfide group equivalent 200 g / eq.)
* 5: HF4M (manufactured by Meiwa Kasei Co., Ltd., phenol novolac resin, hydroxyl equivalent 105 g / eq.)
* 6: Epicron HPC8000 (manufactured by DIC Corporation, active ester resin, active ester group equivalent 223 g / eq.)
* 7: Bisphenol A diacetate (manufactured by Tokyo Chemical Industry Co., Ltd., active ester compound, active ester group equivalent 156 g / eq.)
* 8: 2E4MZ (2-ethyl-4-methylimidazole, manufactured by Shikoku Chemicals Co., Ltd.)
* 9: Admafine SO-C2 (silica, manufactured by Admatex Co., Ltd.)
* 10: Dispersion liquid of fine cellulose powder prepared above (solid content concentration 5.0% by mass)

As is clear from the results shown in Table 1, by using a combination of an epoxy compound and an episulfide compound as the thermosetting resin, and by using a fine cellulose powder and a filler other than the fine cellulose powder in combination, low thermal expansion It was confirmed that a cured product having low elasticity, excellent toughness (flexibility) and low water absorption while maintaining the coefficient was obtained. According to the curable resin composition of the present invention, it is possible to obtain an interlayer insulating material suitable for a thin plate substrate or a multilayer buildup structure.

Claims (4)

  A curable resin composition comprising an epoxy compound, an episulfide compound, a fine cellulose powder having at least one dimension smaller than 100 nm, and a filler other than the fine cellulose powder.   A dry film comprising the curable resin composition according to claim 1 and a resin layer formed by coating and drying the film.   A curable resin composition according to claim 1, or a cured product obtained by curing the resin layer of the dry film according to claim 2. An electronic component comprising the cured product according to claim 3.