JP7550566B2 - Heat dissipating resin composition - Google Patents

Description

The present invention relates to a heat dissipation resin composition. The present invention further relates to a heat dissipation resin composition for power devices, a heat dissipation resin composition for electromagnetic wave shielding, a heat dissipation resin composition for heat dissipation resin substrates, and a heat dissipation resin composition for sealing materials.

In recent years, the heat generated by electronic devices that handle large volumes of information at high speeds, such as digital home appliances, has been increasing rapidly. As such electronic devices continue to become smaller, lighter, and thinner, the components that make up electronic devices are increasingly being replaced by plastic molded bodies rather than metal ones, making it increasingly important to dissipate heat from plastic molded bodies as efficiently as possible.

For example, Patent Document 1 discloses a heat dissipation material made of a composite of thermally conductive inorganic particles and cellulose nanofibers, the surfaces of which have been modified with an ester compound and/or etherification.

However, Patent Document 1 also stated that if the acrylic resin or the like exceeds 25 volume percent, there is a risk that the thermal conductivity of the heat dissipation material may decrease (paragraph 0029).

JP 2016-079202 A

The present invention therefore relates to a resin molded article with excellent heat dissipation properties, i.e., a resin molded article with high thermal conductivity, and a heat dissipating resin composition capable of molding such a resin molded article. Furthermore, the present invention relates to a resin composition for power devices, a resin composition for electromagnetic shielding, a resin composition for heat dissipating resin substrates, and a resin composition for sealing materials, all of which exhibit excellent heat dissipation properties.

The present invention relates to the following [1] to [5].
[1] A heat dissipating resin composition containing modified cellulose and a resin.
[2] The heat dissipating resin composition according to [1] above, further comprising inorganic particles.
[3] A resin molded product obtained by molding the heat dissipating resin composition according to [1] or [2] above.
[4] The heat dissipating resin composition according to [1] or [2] above, which is for use in a power device, an electromagnetic wave shield, a heat dissipating resin substrate, or an encapsulant.
[5] The resin molded article according to [3] above, which is used for a resin molding material, an electrical insulating material, a paint, an ink, a coating agent, a conductive paste, an adhesive, a lens, a transparent resin material, a three-dimensional modeling material, a cushioning material, a repair material, a pressure-sensitive adhesive, a sealing material, a heat insulating material, a sound absorbing material, an artificial leather material, an electronic material, a packaging material, a tire, an automobile part, a fiber composite material, a hollow fiber, or a dialysis membrane.

The resin molded article obtained by molding the resin composition of the present invention has the effect of having excellent heat dissipation properties.

1 is a graph showing the relationship between the content of modified cellulose in the resin molded products produced in the examples and comparative examples of the present invention and the thermal conductivity of the resin molded products, where the horizontal axis of the graph is the cellulose content (volume %) in the modified cellulose, and the vertical axis is the thermal conductivity (W/m K).

As a result of the inventors' investigation into the composition of resin molded bodies with excellent heat dissipation properties, they discovered that by using a specific modified cellulose as the cellulose component, even compositions (molded bodies) with a high resin ratio can exhibit excellent heat dissipation properties, leading to the completion of the present invention. The mechanism by which the effects of the present invention are exhibited is unclear, but it is presumed that this is because heat is easily transferred through highly crystalline cellulose.

<Resin composition for heat dissipation>
The heat dissipating resin composition of the present invention contains modified cellulose and a resin.

[Modified cellulose]
The modified cellulose in the present invention is preferably a modified cellulose in which a modifying group is bonded to the anionic group of an anionically modified cellulose.

(Anionically modified cellulose)
Anion-modified cellulose is cellulose having an anionic group, for example, one or more groups selected from the group consisting of a carboxy group, a phosphate group, and a sulfonic acid group, in the molecule. The introduction of an anionic group into cellulose can be achieved by the method described below. From the viewpoint of availability and effectiveness, anion-modified cellulose having a carboxy group as the anionic group is preferred, and anion-modified cellulose in which the group (-CH ₂ OH) at the C6 position of the glucose unit constituting cellulose is selectively converted to a carboxy group (referred to as "oxidized cellulose") is more preferred. The ion (counter ion) that is paired with the anionic group is preferably a proton.

The anionic group content in the anion-modified cellulose is preferably 0.1 mmol/g or more, more preferably 0.4 mmol/g or more, and even more preferably 0.6 mmol/g or more, from the viewpoint of stable introduction of modifying groups. Also, from the viewpoint of improving handleability, it is preferably 3 mmol/g or less, more preferably 2 mmol/g or less, even more preferably 1.8 mmol/g or less, and even more preferably 1.5 mmol/g or less. The "anionic group content" means the total amount of anionic groups in the glucose constituting the cellulose, and is specifically measured by the method described in the Examples below.

The preferred ranges for the average fiber diameter and length of anionically modified cellulose are the same as those of the raw cellulose, although this depends on the order of the manufacturing process.

The modification group is bonded to the anionic group of the anion-modified cellulose means that the modification group is bonded to the anionic group, preferably the carboxy group, of the anion-modified cellulose. The bond between the modification group and the anionic group can be an ionic bond and/or a covalent bond. Examples of the covalent bond include an amide bond, an ester bond, and a urethane bond, and an amide bond is preferred.

(Modifying Group)
The modifying group may be a hydrocarbon group, a hydrocarbon group with a polymerized or copolymerized portion, or a silicone group. These modifying groups may be bonded (introduced) to cellulose either alone or in combination of two or more.

(1) Hydrocarbon Group Examples of the hydrocarbon group include chain saturated hydrocarbon groups, chain unsaturated hydrocarbon groups, cyclic saturated hydrocarbon groups, and aromatic hydrocarbon groups.

As a chain saturated hydrocarbon group, those having 1 to 30 carbon atoms are preferred, and specific examples include, for example, methyl group, ethyl group, propyl group, isopropyl group, butyl group, sec-butyl group, tert-butyl group, isobutyl group, pentyl group, tert-pentyl group, isopentyl group, hexyl group, isohexyl group, heptyl group, octyl group, 2-ethylhexyl group, nonyl group, decyl group, dodecyl group, tridecyl group, tetradecyl group, octadecyl group, docosyl group, and octacosanyl group.

The chain unsaturated hydrocarbon group preferably has 2 to 30 carbon atoms, and specific examples include ethenyl, propenyl, butenyl, isobutenyl, isoprenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, dodecenyl, tridecenyl, tetradecenyl, and octadecenyl.

As the cyclic saturated hydrocarbon group, those having 3 to 20 carbon atoms are preferable, and specific examples include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, a cyclodecyl group, a cyclododecyl group, a cyclotridecyl group, a cyclotetradecyl group, and a cyclooctadecyl group.

Examples of aromatic hydrocarbon groups include aryl groups and aralkyl groups. In the aryl group and aralkyl group, the aromatic ring itself may be substituted or unsubstituted.

The total number of carbon atoms in the aryl group is preferably 6 or more and 24 or less, and specific examples of the aryl group include a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, a biphenyl group, a triphenyl group, a terphenyl group, and groups in which these groups are substituted with a substituent.

The total number of carbon atoms in the aralkyl group is preferably 7 or more and 24 or less. Specific examples of aralkyl groups include benzyl groups, phenethyl groups, phenylpropyl groups, phenylpentyl groups, phenylhexyl groups, phenylheptyl groups, phenyloctyl groups, and groups in which the aromatic groups of these groups are substituted with substituents.

(2) Hydrocarbon group with polymerized or copolymerized portion The polymerized portion is a structure in which ethylene oxide (EO) or propylene oxide (PO) is polymerized in a linear chain. In this specification, such a structure is referred to as an EO polymerized portion or a PO polymerized portion. In addition, the copolymerized portion is a structure in which ethylene oxide (EO) and propylene oxide (PO) are polymerized in a random or block shape. In this specification, such a structure is referred to as an (EO/PO) copolymerized portion.

Examples of hydrocarbon groups with EO polymerization parts, PO polymerization parts, or EO/PO copolymerization parts include those represented by the following formula:

(In the formula, R ¹ represents a hydrogen atom, a hydrocarbon group having from 1 to 6 carbon atoms, or a -CH ₂ CH(CH ₃ )NH ₂ group. EO and PO are present randomly or in a block form, a represents 0 or a positive number indicating the average number of moles of EO added, and b represents 0 or a positive number indicating the average number of moles of PO added. However, a and b cannot be 0 at the same time.)

In the above formula, a is preferably 0 or more, more preferably 1 or more, more preferably 5 or more, more preferably 11 or more, and more preferably 15 or more, from the viewpoint of obtaining a resin molded product with excellent heat dissipation properties, and from the same viewpoint, it is preferably 100 or less, and more preferably 70 or less.

In the above formula, b is preferably 0 or more, more preferably 1 or more, and more preferably 3 or more, from the viewpoint of obtaining a resin molded product with excellent heat dissipation properties, and from the same viewpoint, it is preferably 50 or less, and more preferably 40 or less.

In the above formula, a+b indicates the average number of moles of EO and PO added together, and from the viewpoint of obtaining a resin molded product with excellent heat dissipation, it is preferably 4 or more, more preferably 6 or more, and more preferably 8 or more, and from the same viewpoint, it is preferably 100 or less, and more preferably 70 or less.

The PO content (mol %) in the EO/PO copolymer portion is preferably 1 mol % or more, more preferably 5 mol % or more, while it is preferably 100 mol % or less, more preferably 90 mol % or less.

The molecular weight of the EO polymerization portion, PO polymerization portion or EO/PO copolymerization portion is preferably 200 or more, more preferably 500 or more, more preferably 1,000 or more, and is preferably 10,000 or less, more preferably 7,000 or less. The PO content in the EO/PO copolymerization portion and the molecular weight of the EO/PO copolymerization portion can be calculated from the average number of moles added when producing an amine compound having a hydrocarbon group with an EO/PO copolymerization portion described below.

In terms of obtaining a resin molded product having excellent heat dissipation properties, R ¹ in the formula of the hydrocarbon group having the above-mentioned EO polymerization portion, PO polymerization portion, or EO/PO copolymerization portion is preferably a hydrogen atom. The hydrocarbon group having 1 to 6 carbon atoms is preferably a methyl group, an ethyl group, or an iso- or normal propyl group.

(3) Silicone Group A silicone group is a monovalent group having a siloxane bond as the main chain, which may have an alkylene group attached thereto.

(4) Further Substituents The modifying group may further have a substituent. Examples of the substituent include alkoxy groups having 1 to 6 carbon atoms, such as methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, sec-butoxy, tert-butoxy, pentyloxy, isopentyloxy, and hexyloxy; methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, isopropoxycarbonyl, butoxycarbonyl, isobutoxycarbonyl, and sec-butoxycarbonyl; Examples of such an alkoxy group include alkoxy-carbonyl groups having 1 to 6 carbon atoms, such as a carboxyl group, a tert-butoxycarbonyl group, a pentyloxycarbonyl group, or an isopentyloxycarbonyl group; halogen atoms such as a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom; acyl groups having 1 to 6 carbon atoms, such as an acetyl group or a propionyl group; aralkyl groups; aralkyloxy groups; alkylamino groups having 1 to 6 carbon atoms; and dialkylamino groups having an alkyl group with 1 to 6 carbon atoms.

[Method for producing modified cellulose]
The modified cellulose can be produced, for example, by introducing anionic groups into raw cellulose to produce anionically modified cellulose (step 1), and then bonding modifying groups to the anionic groups of the anionically modified cellulose (step 2).

(Step 1)
Cellulose as raw material As the cellulose as the raw material for anion-modified cellulose, natural cellulose is preferred from an environmental perspective, and examples thereof include wood pulp such as coniferous pulp and hardwood pulp; cotton pulp such as cotton linter and cotton lint; non-wood pulp such as straw pulp and bagasse pulp; bacterial cellulose, and the like. These may be used alone or in combination of two or more.

The average fiber diameter of the raw cellulose is not particularly limited, but from the viewpoints of ease of handling and cost, it is preferably 5 μm or more, more preferably 7 μm or more, and from the same viewpoint, it is preferably 500 μm or less, more preferably 300 μm or less. The average fiber diameter of the raw cellulose is determined by the method described in the Examples below.

The average fiber length of the raw cellulose is not particularly limited, but from the viewpoints of availability and cost, it is preferably 5 μm or more, more preferably 25 μm or more, and from the same viewpoint, it is preferably 5,000 μm or less, more preferably 3,000 μm or less. The average fiber length of the raw cellulose can be measured according to the method described in the Examples below.

Treatment Method
(1) Introducing a carboxy group into cellulose as an anionic group Examples of a method for introducing a carboxy group into cellulose include a method of oxidizing a hydroxy group of cellulose to convert it into a carboxy group, and a method of reacting a hydroxy group of cellulose with at least one selected from the group consisting of a compound having a carboxy group, an acid anhydride of a compound having a carboxy group, and derivatives thereof.

Methods for oxidizing the hydroxyl groups of cellulose include, for example, the method described in JP 2015-143336 A or JP 2015-143337 A, in which 2,2,6,6-tetramethyl-1-piperidine-N-oxyl (TEMPO) is used as a catalyst to react the raw cellulose with an oxidizing agent such as sodium hypochlorite and a bromide such as sodium bromide. By oxidizing cellulose using TEMPO as a catalyst, the group at the C6 position of the glucose of the cellulose building blocks is selectively converted to a carboxy group, and the above-mentioned oxidized cellulose can be obtained.

The compound having a carboxy group to be used for introducing a carboxy group into cellulose is not particularly limited, but specifically includes halogenated acetic acid, such as chloroacetic acid.
The acid anhydrides of compounds having a carboxyl group and their derivatives for use in introducing a carboxyl group into cellulose are not particularly limited, and examples thereof include acid anhydrides of dicarboxylic acid compounds such as maleic anhydride, succinic anhydride, phthalic anhydride, and adipic anhydride, imidized products of acid anhydrides of compounds having a carboxyl group, and derivatives of acid anhydrides of compounds having a carboxyl group. These compounds may be substituted with a hydrophobic group.

(2) Introducing a Sulfonic Acid Group or a Phosphate Group into Cellulose as an Anionic Group As a method for introducing a sulfonic acid group into cellulose, a method of adding sulfuric acid to cellulose and heating the cellulose may be mentioned.
Methods for introducing phosphate groups into cellulose include a method of mixing a powder or an aqueous solution of phosphoric acid or a phosphoric acid derivative with cellulose in a dry or wet state, a method of adding an aqueous solution of phosphoric acid or a phosphoric acid derivative to a dispersion of cellulose, etc. When these methods are adopted, in general, after mixing or adding a powder or an aqueous solution of phosphoric acid or a phosphoric acid derivative, a dehydration treatment, a heat treatment, etc. are carried out.

(Step 2)
Introduction of a modifying group into the anionic group of anion-modified cellulose is achieved by reacting a compound for introducing a modifying group into the anionic group (referred to as a "modifying compound") with anion-modified cellulose. As a method for introducing a modifying group, (1) when the modifying group is introduced via an ionic bond, JP-A-2015-143336 can be referred to, and (2) when the modifying group is introduced via an amide bond, JP-A-2015-143337 can be referred to.
After completion of step 2, post-treatment may be appropriately carried out in order to remove unreacted compounds, etc. Examples of methods for the post-treatment include filtration, centrifugation, dialysis, etc.

(1) Aspect of introduction via ionic bond When oxidized cellulose is used as the anionically modified cellulose and a compound having an amino group (for example, an amine compound having a hydrocarbon group, an amine compound having a hydrocarbon group with a copolymerized portion, and an amine compound having a silicone group) is used as the modifying compound, modifying groups ^R0 , ^R1 , ^R2 , and ^R3 can be introduced into the cellulose via ionic bonds as shown in the following formula: ^R0 , ^R1 , ^R2 , and ^R3 may be the same or different, and may be hydrogen atoms (except when all of ^R0 , ^R1 , ^R2 , and ^R3 are hydrogen atoms).

When introducing a modifying group via an ionic bond, the oxidized cellulose and the modifying compound are mixed, which forms an ionic bond between the carboxy group contained in the oxidized cellulose and the amino group of the modifying compound.

Modifying Compound The modifying compound used in this embodiment may be any compound capable of introducing a desired modifying group, and preferable examples thereof include amine compounds and phosphonium compounds having the above-mentioned hydrocarbon group, a hydrocarbon group with a copolymerized portion, or a silicone group.

Amine compound The amine compound is, for example, an amine compound having the above-mentioned hydrocarbon group, the above-mentioned hydrocarbon group with a copolymer portion, or the above-mentioned silicone group as a modifying group, and such a hydrocarbon group or the like is introduced into the anion-modified cellulose via an ionic bond to become a modifying group in the modified cellulose.

The amine compound may be any of primary amines, secondary amines, tertiary amines, and quaternary ammonium compounds. From the viewpoint of reactivity, the anion component of the quaternary ammonium compound is preferably a halogen ion such as a chloride ion or a bromide ion, a hydrogen sulfate ion, a perchlorate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, a trifluoromethanesulfonate ion, or a hydroxyl ion.

Specific examples of the amine compound having a hydrocarbon group include primary, secondary and tertiary amines such as ethylamine, diethylamine, triethylamine, propylamine, dipropylamine, butylamine, dibutylamine, hexylamine, 2-ethylhexylamine, dihexylamine, trihexylamine, octylamine, dioctylamine, trioctylamine, dodecylamine, didodecylamine, stearylamine, distearylamine, monoethanolamine, diethanolamine, triethanolamine, oleylamine, aniline, octadecylamine, dimethylbehenylamine and benzylamine. Examples of quaternary ammonium compounds include tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), tetraethylammonium chloride, tetrapropylammonium hydroxide (TPAH), tetrabutylammonium hydroxide (TBAH), tetrabutylammonium chloride, lauryltrimethylammonium chloride, dilauryldimethyl chloride, stearyltrimethylammonium chloride, distearyldimethylammonium chloride, cetyltrimethylammonium chloride, and alkylbenzyldimethylammonium chloride.

Amine compounds having a hydrocarbon group can be commercially available or prepared according to known methods.

Amine compound having a hydrocarbon group with a polymerized or copolymerized portion The EO polymerized portion, the PO polymerized portion or the EO/PO copolymerized portion and the nitrogen atom of the amine compound are preferably bonded directly or via a linking group. The linking group is preferably a hydrocarbon group, and an alkylene group having preferably 1 to 6 carbon atoms, more preferably 1 to 3 carbon atoms, is mentioned. For example, an ethylene group or a propylene group is preferable.

Examples of amines having a hydrocarbon group with an EO polymerized portion, a PO polymerized portion, or an EO/PO copolymerized portion include those represented by the following formula (i):

In formula (i), R ¹ , a and b are the same as R ¹ , a and b in the above-mentioned formula for the hydrocarbon group having an EO polymerized portion, a PO polymerized portion or an EO/PO copolymerized portion.

The amine compound having a hydrocarbon group with an EO polymerization part, a PO polymerization part, or an EO/PO copolymerization part represented by formula (i) can be prepared according to a known method. For example, a desired amount of ethylene oxide or propylene oxide may be added to a propylene glycol alkyl ether, and then the hydroxyl group terminal may be aminated. If necessary, the alkyl ether may be cleaved with an acid to convert the terminal to a hydrogen atom. For these production methods, refer to JP-A-3-181448, and details of such an amine compound are described, for example, in JP-A-6105139.

The amine having a hydrocarbon group with the EO polymerization portion or PO polymerization portion may be, for example, a commercially available product. Specific examples include SUNBRIGHT MEPA-10H, SUNBRIGHT MEPA-20H, SUNBRIGHT MEPA-50H, SUNBRIGHT MEPA-10T, SUNBRIGHT MEPA-12T, SUNBRIGHT MEPA-20T, SUNBRIGHT MEPA-30T, SUNBRIGHT MEPA-40T, etc., manufactured by NOF Corporation. The amine having a hydrocarbon group with an EO/PO copolymerization portion may be, for example, a commercially available product. Specific examples thereof include Jeffamine M-2070, Jeffamine M-2005, Jeffamine M-2095, Jeffamine M-1000, Jeffamine M-600, Surfoamine B200, Surfoamine L100, Surfoamine L200, Surfoamine L207, Surfoamine L300, Surfoamine B-100, XTJ-501, XTJ-506, XTJ-507, XTJ-508, M3000, Jeffamine ED-600, Jeffamine ED-900, Jeffamine ED-2003, Jeffamine D-230, Jeffamine D-400, Jeffamine D-2000, and Jeffamine ED-2003, all of which are manufactured by HUNTSMAN. D-4000, XTJ-510, Jeffamine T-3000, Jeffamine T-5000, XTJ-502, XTJ-509, XTJ-510, etc. These may be used alone or in combination of two or more.

Amine compound having a silicone group: For example, such an amine compound may have a structure in which an amino group is bonded to the skeleton of a silicone group via an alkylene group or the like. In this specification, such an amine compound may be referred to as an "amino-modified silicone compound". The amino-modified silicone compound may be a commercially available product or may be prepared according to a known method. Only one type of amino-modified silicone compound may be used, or two or more types may be used.

Examples of the amino-modified silicone compound that may be used from the viewpoint of performance include TSF4703 (kinetic viscosity: 1000, amino equivalent: 1600) and TSF4708 (kinetic viscosity: 1000, amino equivalent: 2800) manufactured by Momentive Performance Materials, Inc., SS-3551 (kinetic viscosity: 1000, amino equivalent: 1600), SF8457C (kinetic viscosity: 1200, amino equivalent: 1800), SF8417 (kinetic viscosity: 1200, amino equivalent: 1700), and BY16-209 (kinetic viscosity: 500, amino equivalent: 1800) manufactured by Dow Corning Toray Silicone Co., Ltd., and BY16-892 (kinetic viscosity: 1500, amino equivalent: 2000), BY16-898 (kinetic viscosity: 2000, amino equivalent: 2900), FZ-3760 (kinetic viscosity: 220, amino equivalent: 1600), Shin-Etsu Chemical Co., Ltd.'s KF8002 (kinetic viscosity: 1100, amino equivalent: 1700), KF867 (kinetic viscosity: 1300, amino equivalent: 1700), KF-864 (kinetic viscosity: 1700, amino equivalent: 3800), BY16-213 (kinetic viscosity: 55, amino equivalent: 2700), BY16-853U (kinetic viscosity: 14, amino equivalent: 450) are preferred. In (), the kinetic viscosity indicates the measured value (unit: mm ² /s) at 25 ° C., and the unit of amino equivalent is g / mol.

Reaction conditions, etc. The amount of modifying compound used is, from the viewpoint of reactivity, an amount such that the number of amino groups in the modifying compound is preferably 0.01 mol or more, more preferably 0.1 mol or more, even more preferably 0.5 mol or more, even more preferably 0.7 mol or more, and even more preferably 1 mol or more, per mol of carboxy groups in the oxidized cellulose, and, from the viewpoint of product purity, is preferably an amount such that the number of amino groups is 50 mol or less, more preferably 20 mol or less, and even more preferably 10 mol or less. When the modifying compound has multiple amino groups, it is used so that the total number of moles of amino groups is the above-mentioned number of moles.

It is preferable to use a solvent when mixing. As the solvent, it is preferable to select a solvent in which the compound used dissolves. Examples of the solvent include methanol, ethanol, isopropanol (IPA), N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N,N-dimethylacetamide, tetrahydrofuran (THF), acetone, methyl ethyl ketone (MEK), cyclohexanone, ethyl acetate, acetonitrile, dichloromethane, chloroform, toluene, acetic acid, water, etc., and these can be used alone or in combination of two or more.

From the viewpoint of the reactivity of the compound, the temperature during mixing is preferably 0°C or higher, more preferably 5°C or higher, and even more preferably 10°C or higher. From the viewpoint of suppressing discoloration of the modified cellulose, the temperature is preferably 50°C or lower, more preferably 40°C or lower, and even more preferably 30°C or lower. The mixing time can be set appropriately depending on the type of compound and solvent used, but from the viewpoint of the reactivity of the compound, it is preferably 0.01 hours or higher, more preferably 0.1 hours or higher, and from the viewpoint of productivity, it is preferably 48 hours or lower, more preferably 24 hours or lower.

(2) Aspect of introduction via amide bond When oxidized cellulose is used as the anion-modified cellulose and a compound having an amino group (e.g., an amine compound having a hydrocarbon group, an amine compound having a hydrocarbon group with a copolymerized moiety, and an amine compound having a silicone group) is used as the modifying compound, modifying groups ^R1 and ^R2 can be introduced into the cellulose via an amide bond as shown in the following formula: In the following formula, ^R1 and ^R2 may be the same or different, and either one may be a hydrogen atom.

When introducing a modifying group via an amide bond, the anion-modified cellulose and the modifying compound are mixed in the presence of a known condensing agent, which causes a condensation reaction between the carboxy group contained in the oxidized cellulose and the amino group of the modifying compound to form an amide bond.

Modifying Compound The modifying compound used in this embodiment may be any compound capable of introducing a desired modifying group, and preferably includes an amine compound having the aforementioned hydrocarbon group, a hydrocarbon group with a copolymer portion, or a silicone group.

Amine compound The amine compound is, for example, an amine compound having the above-mentioned hydrocarbon group, the above-mentioned hydrocarbon group accompanied by a copolymer portion, or the above-mentioned silicone group as a modifying group, and such a hydrocarbon group or the like is introduced into the anion-modified cellulose via an amide bond to become a modifying group in the modified cellulose.

Examples of the amine compound include primary amines and secondary amines. Specific examples of the amine compound include the primary amines and secondary amines among the amine compounds having a hydrocarbon group, the amine compounds having a hydrocarbon group with a copolymerized portion, and the amine compounds having a silicone group, all of which are exemplified in the above "(1) Aspect of introduction via ionic bond".

Reaction Conditions The amount of modifying compound used is, from the viewpoint of reactivity, an amount such that the number of amino groups in the modifying compound is preferably 0.1 mol or more, more preferably 0.5 mol or more, per mol of carboxy groups in the oxidized cellulose, and, from the viewpoint of product purity, an amount such that the number of amino groups is preferably 50 mol or less, more preferably 20 mol or less, and even more preferably 10 mol or less. When the modifying compound has multiple amino groups, it is used so that the total number of moles of amino groups is the above number of moles.

The condensation agent is not particularly limited, but includes those described on page 116 of Synthetic Chemistry Series: Peptide Synthesis (Maruzensha) or those described in Tetrahedron, 57, 1551 (2001), such as 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (hereinafter sometimes referred to as "DMT-MM").

In the amidation reaction, it is preferable to use a solvent. It is preferable to select a solvent in which the compound used dissolves. Specific examples of the solvent include the solvents exemplified in "(1) Aspect of introduction via ionic bond" above.

The reaction time and reaction temperature in the amidation reaction can be appropriately selected depending on the type of compound and solvent used, but from the viewpoint of reaction rate, it is preferably 1 to 24 hours, more preferably 10 to 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. From the viewpoint of product quality such as coloration, it is preferably 200°C or lower, more preferably 80°C or lower, and even more preferably 30°C or lower.

(Micronization process)
By micronizing the cellulose at any stage of the production method of the modified cellulose (for example, before step 1, before step 2, and after step 2), the cellulose on the micrometer scale can be micronized to the nanometer scale. By reducing the average fiber diameter to the nanometer size, the dispersibility in the resin is improved, which is preferable.

For the micronization process, known micronization processes can be used. For example, to obtain modified cellulose with an average fiber diameter of nanometer size, a process using a grinder such as a mass colloider or a process using a high-pressure homogenizer in a medium can be carried out.

Examples of the medium include alcohols having 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms, such as water, methanol, ethanol, and propanol; ketones having 3 to 6 carbon atoms, such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; ketones having 2 to 4 carbon atoms, such as ethyl acetate and butyl acetate; 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 alkyl ethers having 2 to 5 carbon atoms; and polar solvents such as N,N-dimethylformamide (DMF), N,N-dimethylacetamide, and dimethylsulfoxide. These can be used alone or in combination of two or more. The amount of the medium used may be an effective amount that can disperse the modified cellulose, and is preferably at least 1 time by weight, more preferably at least 2 times by weight, and more preferably at most 500 times by weight, and more preferably at most 200 times by weight, relative to the modified cellulose.

As the equipment used in the micronization process, in addition to a high-pressure homogenizer, a known dispersing machine can be suitably used. For example, a disintegrator, a beater, a low-pressure homogenizer, a grinder, a mass colloider, a cutter mill, a ball mill, a jet mill, a single-screw extruder, a twin-screw extruder, an ultrasonic agitator, a household juicer mixer, etc. can be used. In addition, the solid content of the modified cellulose in the micronization process is preferably 50 mass% or less.

[Properties of modified cellulose]
The main properties of the modified cellulose in the present invention are as follows:

(Average fiber diameter)
The average fiber diameter of the modified cellulose is preferably 5 μm or more, regardless of the type of modifying group. From the viewpoints of handling, availability, and cost, it is more preferably 7 μm or more, even more preferably 10 μm or more, and even more preferably 15 μm or more. In addition, although there is no particular upper limit, from the viewpoint of handling, it is preferably 10,000 μm or less, more preferably 5,000 μm or less, even more preferably 1,000 μm or less, even more preferably 500 μm or less, and even more preferably 100 μm or less. The average fiber diameter of the modified cellulose is determined by the method described in the Examples below.

The modified cellulose may be one that has been subjected to a micronization process to have nanometer size. In this case, the average fiber diameter of the modified cellulose is preferably 1 nm or more, more preferably 2 nm or more, from the viewpoints of handling, availability, and cost, and is preferably 500 nm or less, more preferably 300 nm or less, even more preferably 200 nm or less, even more preferably 150 nm or less, and even more preferably 120 nm or less, from the viewpoints of handling and solvent dispersibility. The average fiber diameter of the modified cellulose that has been subjected to a micronization process is determined by the method described in the Examples below.

(Amount and introduction rate of modifying group)
The amount of the modifying group bonded to the modified cellulose is preferably 0.01 mmol/g or more from the viewpoint of dispersibility, and is preferably 3.0 mmol/g or less from the same viewpoint. When any two or more types of modifying groups are simultaneously introduced into the modified cellulose as the modifying groups, the amount of the modifying groups bonded is preferably within the above range.

From the viewpoint of dispersibility, the introduction rate of the modifying group in the modified cellulose is preferably 10 mol% or more, and the higher the better, preferably 100 mol%. When any two or more types of modifying groups are simultaneously introduced as the modifying groups, it is preferable that the total introduction rate is within the above range, so long as it does not exceed the upper limit of 100 mol%.

The amount and introduction rate of the modifying group bonded can be adjusted by the type and amount of the modifying compound added, the reaction temperature, the reaction time, the type of solvent, etc. The amount (mmol/g) and introduction rate (mol%) of the modifying group refer to the amount and ratio of the modifying group introduced (bonded) to the anionic group in the modified cellulose. For example, when the anionic group is a carboxy group, the amount and introduction rate of the modifying group bonded to the modified cellulose are calculated by the method described in the Examples below.

(Crystal Structure)
The modified cellulose preferably has a cellulose I type crystal structure, and the crystallinity of the modified cellulose is preferably 10% or more, more preferably 15% or more, and even more preferably 20% or more from the viewpoint of strength expression of a molded body of the resin composition. In addition, from the viewpoint of raw material availability, it is preferably 90% or less, more preferably 85% or less, even more preferably 80% or less, and even more preferably 75% or less. In this specification, the crystallinity of cellulose is the cellulose I type crystallinity calculated from the diffraction intensity value by the X-ray diffraction method, and can be measured according to the method described in the examples below. In addition, cellulose I type refers to the crystalline form of natural cellulose, and cellulose I type crystallinity means the proportion of the amount of crystalline region in the entire cellulose. The presence or absence of cellulose I type crystal structure can be determined by the presence of a peak at 2θ = 22.6 ° in X-ray diffraction measurement.

〔resin〕
The resin in the present invention is preferably a curable resin. Examples of the curable resin include a urethane resin, a (meth)acrylic resin, an epoxy resin, a urea resin, a melamine resin, and a phenol resin. Of these, one or more resins selected from the group consisting of a urethane resin, a (meth)acrylic resin, and an epoxy resin are preferred.

When the curable resin is a urethane resin, examples of the curable monomer include aromatic isocyanates such as tolylene diisocyanate and diphenylmethane diisocyanate, and aliphatic isocyanates such as hexamethylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, and tetramethylxylylene diisocyanate, and polyols such as ethylene glycol, diethylene glycol, butanediol, hexanediol, neopentyldiol, hydroxyethyl acrylate, trimethylolpropane, dimethylolpropionic acid, and isophoronediamine. The reaction product of an isocyanate and a polyol becomes a urethane resin, but this is not limited to this. Oligomers of the polyols listed above, and polyols such as polyether polyols, polyester polyols, and polycarbonate polyols may also be used as the curable prepolymer.

When the curable resin is a (meth)acrylic resin, examples of the curable monomer include mono(meth)acrylates such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, n-hexyl acrylate, n-hexyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, nonanediol diacrylate, phenoxyethyl acrylate, (meth)acrylates of bisphenol A-alkylene oxide adducts, epoxy (meth)acrylates (bisphenol A type epoxy (meth)acrylate, novolac type epoxy (meth)acrylate, etc.), polyester (meth)acrylates (for example, aliphatic polyester type (meth)acrylate, aromatic polyester type (meth)acrylate, etc.), urethane (meth)acrylates (polyester type urethane (meth)acrylate, polyether type urethane (meth)acrylate, etc.), silicone (meth)acrylate, and cyanoacrylate. Oligomers of the mono(meth)acrylates listed above may be used as curable prepolymers.

When the curable resin is an epoxy resin, examples of the curable monomer include bisphenol A type, phenol novolac type, glycidyl ether type, alicyclic type, glycidyl amine type, and glycidyl ester type monomers. Oligomers of the monomers listed above may also be used as the curable prepolymer.

When the curable resin is a urea resin, examples of the curable monomers include urea and formaldehyde. When the curable resin is a melamine resin, examples of the curable monomers include melamine and formaldehyde. When the curable resin is a phenolic resin, examples of the curable monomers include phenol, cresol, xylenol, resorcinol, and formaldehyde.

[Curing agent and curing accelerator]
When the resin contains a thermosetting resin, the heat dissipating resin composition of the present invention may contain a curing agent and/or a curing accelerator.

The curing agent can be appropriately selected depending on the type of resin. For example, when the resin is an epoxy resin, examples of the curing agent include amine-based curing agents, phenolic resin-based curing agents, acid anhydride-based curing agents, polymercaptan-based curing agents, and latent curing agents (boron trifluoride-amine complex, dicyandiamide, carboxylic acid hydrazide, etc.). The curing agent may be used alone or in combination of two or more kinds. The curing agent may also act as a curing accelerator.

The ratio of the hardener can be selected appropriately depending on the type of hardener, but is preferably 0.1 to 300 parts by weight per 100 parts by weight of resin, for example.

The curing accelerator can also be appropriately selected depending on the type of resin. For example, when the resin is an epoxy resin, examples of the curing accelerator include phosphines and amines. The curing accelerators may be used alone or in combination of two or more types.

The proportion of the curing accelerator can be selected appropriately depending on the type of curing agent, but is preferably 0.01 to 100 parts by mass per 100 parts by mass of resin, for example.

[Inorganic particles]
The composition of the present invention preferably further contains inorganic particles, which is expected to have the effect of further increasing thermal conductivity.
The inorganic particles preferably have thermal conductivity. Specifically, boron nitride, aluminum nitride, silicon nitride, gallium nitride, magnesium oxide, zinc oxide, aluminum oxide, silicon carbide, and silicon dioxide can be mentioned. Only one type of inorganic particles may be used, or two or more types may be used.

From the viewpoint of heat dissipation effect, the average particle diameter of the inorganic particles is preferably 0.1 μm or more, more preferably 0.5 μm or more, while from the same viewpoint, it is preferably 100 μm or less, more preferably 50 μm or less. The average particle diameter of the inorganic particles is determined by measuring the particle diameters (average of the major axis and minor axis) of 500 particles from a scanning electron microscope (SEM) photograph, and taking the number average value of these.

[Solvent or Dispersion Medium]
The heat dissipating resin composition may contain a solvent or a dispersion medium within a range that does not impair the effects of the present invention. Examples of such a solvent or the like in the present invention include organic solvents and organic media containing reactive functional groups, and are not particularly limited as long as they are used in the field of coating materials.

From the viewpoint of smoothness and heat resistance, the solvent used in the present invention preferably has a dielectric constant at 25°C of 75 or less, more preferably 55 or less, even more preferably 45 or less, preferably 1 or more, more preferably 2 or more, and even more preferably 3 or more. The dielectric constant of the solvent can be measured at 25°C using a liquid dielectric constant meter Model 871 (manufactured by Nippon Luft Co., Ltd.).

Examples of organic solvents include alcohols such as methanol, ethanol, isopropyl alcohol, 2-butanol, 1-pentanol, octyl alcohol, glycerin, ethylene glycol, and propylene glycol; carboxylic acids such as acetic acid; hydrocarbons such as hexane, heptane, octane, decane, and liquid paraffin; aromatic hydrocarbons such as toluene and xylene; amides such as dimethyl sulfoxide, N,N-dimethylformamide, dimethylacetamide, and acetanilide; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; halogens such as methylene chloride and chloroform; ethylene Examples of suitable oils include carbonates such as propylene carbonate, dimethyl carbonate, and diethyl carbonate; esters such as methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl butyrate, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitol fatty acid esters, glycerin fatty acid esters, and polyoxyethylene fatty acid esters; polyethers such as polyethylene glycol and polyoxyethylene alkyl ethers; silicone oils such as polydimethylsiloxane; acetonitrile, propionitrile, ester oils, salad oils, soybean oil, and castor oil. These oils may be used alone or in combination of two or more.

Examples of organic media containing reactive functional groups include acrylates such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, n-hexyl acrylate, n-hexyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, and phenyl glycidyl ether acrylate; urethane prepolymers such as hexamethylene diisocyanate urethane prepolymer and phenyl glycidyl ether acrylate toluene diisocyanate urethane prepolymer; glycidyl ethers such as n-butyl glycidyl ether, 2-ethylhexyl glycidyl ether, glycidyl ether of stearic acid, styrene oxide, phenyl glycidyl ether, nonylphenyl glycidyl ether, butylphenyl glycidyl ether, 1,6-hexanediol diglycidyl ether, ethylene glycol diglycidyl ether, and diethylene glycol diglycidyl ether; chlorostyrene, methoxystyrene, butoxystyrene, and vinyl benzoic acid.

When a solvent or dispersion medium is used, the content of the solvent or dispersion medium in the composition of the present invention is preferably 30% by mass or more, more preferably 50% by mass or more, and even more preferably 80% by mass or more, from the viewpoints of smoothness and heat resistance. On the other hand, from the same viewpoint, it is preferably 98% by mass or less, more preferably 97% by mass or less, and even more preferably 96% by mass or less. If necessary, the solvent or dispersion medium may be partially or entirely removed from the composition of the present invention. Therefore, the composition of the present invention may be in the form of a solution or dispersion, or may be in the form of a dried powder.

[Other ingredients]
The heat dissipating resin composition may contain, for example, plasticizers, crystal nucleating agents, fillers (inorganic fillers, organic fillers), hydrolysis inhibitors, flame retardants, antioxidants, lubricants such as hydrocarbon waxes and anionic surfactants, ultraviolet absorbers, antistatic agents, antifogging agents, light stabilizers, pigments, antifungal agents, antibacterial agents, foaming agents, surfactants; starches, polysaccharides such as alginic acid; natural proteins such as gelatin, glue, and casein; inorganic compounds such as tannins, zeolites, ceramics, and metal powders; fragrances; flow regulators; leveling agents; conductive agents; ultraviolet light dispersants; and deodorants, within the scope of the present invention. Furthermore, it is also possible to add other polymeric materials and other compositions within the scope of the present invention.

[Composition of heat dissipating resin composition]
The amount of modified cellulose in the composition of the present invention is preferably 0.2% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more, in terms of cellulose (not including modification groups, etc.) in terms of the blending amount, from the viewpoint of obtaining a resin molded product having excellent heat dissipation, while it is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, and even more preferably 10% by mass or less. In addition, the amount of modified cellulose in the composition of the present invention is preferably 0.2% by volume or more, more preferably 0.4% by volume or more, and even more preferably 0.8% by volume or more, while it is preferably 50% by volume or less, more preferably 40% by volume or less, even more preferably 30% by volume or less, and even more preferably 10% by volume or less. The volume percentage of each component in the heat dissipation resin composition is determined from the volume ratio of each component at the time of blending.

The content of the resin in the composition of the present invention, calculated in terms of the blending amount, is preferably 50% by mass or more, more preferably 75% by mass or more, and even more preferably 90% by mass or more, while it is preferably 99.5% by mass or less, more preferably 99% by mass or less, even more preferably 98% by mass or less, and even more preferably 97% by mass or less. The amount of the resin in the composition of the present invention is preferably 10% by volume or more, more preferably 20% by volume or more, and even more preferably 30% by volume or more, while it is preferably 99.5% by volume or less, more preferably 99% by volume or less, even more preferably 98% by volume or less, and even more preferably 97% by volume or less.

When inorganic particles are contained, the content of inorganic particles in the composition of the present invention is preferably 10% by volume or more, more preferably 20% by volume or more, while it is preferably 90% by volume or less, more preferably 80% by volume or less.

[Method for producing heat dissipating resin composition]
The heat dissipating resin composition of the present invention can be produced, for example, by mixing the modified cellulose and the resin, and further adding a solvent and the like, if necessary.
For example, the above-mentioned components can be melt-kneaded using a known kneader such as an internal kneader, a single-screw or twin-screw extruder, a roll mill, or an open-roll type kneader, or can be sheared by a solvent casting method or by a shearing device such as a high-shear processing machine.

The amount of modified cellulose during mixing is preferably 0.06 parts by mass or more, more preferably 0.12 parts by mass or more, even more preferably 0.36 parts by mass or more, even more preferably 0.6 parts by mass or more, and even more preferably 1 part by mass or more, per 100 parts by mass of resin, from the viewpoint of expressing mechanical properties in a molded article of the resin composition. On the other hand, from the viewpoint of production costs, it is preferably 120 parts by mass or less, more preferably 100 parts by mass or less, even more preferably 60 parts by mass or less, even more preferably 40 parts by mass or less, and even more preferably 20 parts by mass or less.

<Resin Molded Body>
The resin molded article of the present invention is obtained by molding the heat dissipating resin composition of the present invention. The resin molded article can be produced by appropriately using a known molding method such as coating molding, extrusion molding, injection molding, press molding, casting molding, or solvent casting of the composition of the present invention. Among these known molding methods, coating molding is preferred from the viewpoint of productivity.

The amount of modified cellulose in the resin molded product is preferably 0.2% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more, in terms of cellulose (not including modification groups, etc.) in terms of the blending amount, from the viewpoint of obtaining a resin molded product with excellent heat dissipation, while it is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, and even more preferably 10% by mass or less. The amount of modified cellulose in the resin molded product is preferably 0.2% by volume or more, more preferably 0.4% by volume or more, and even more preferably 0.8% by volume or more, while it is preferably 50% by volume or less, more preferably 40% by volume or less, even more preferably 30% by volume or less, and even more preferably 10% by volume or less. The volume percentage of each component in the resin molded product is determined from the volume ratio of each component when blended.

The amount of resin in the resin molded body, calculated in terms of the blending amount, is preferably 50% by mass or more, more preferably 75% by mass or more, and even more preferably 90% by mass or more, while it is preferably 99.5% by mass or less, more preferably 99% by mass or less, even more preferably 98% by mass or less, and even more preferably 97% by mass or less. The amount of resin in the resin molded body is preferably 10% by volume or more, more preferably 20% by volume or more, and even more preferably 30% by volume or more, while it is preferably 99.5% by volume or less, more preferably 99% by volume or less, even more preferably 98% by volume or less, and even more preferably 97% by volume or less.

When the resin molded body contains inorganic particles, the inorganic particles in the resin molded body are preferably 10% by volume or more, more preferably 20% by volume or more, and preferably 90% by volume or less, more preferably 80% by volume or less.

The resin molded body thus obtained has excellent heat dissipation properties, i.e., high thermal conductivity, and can therefore be suitably used as a heat dissipation material. The heat dissipation properties of the resin molded body can be evaluated by measuring the thermal conductivity as described in the examples below.

Specific examples of applications of the resin molded article of the present invention include resin molding materials, electrical insulating materials, paints, inks, coating agents, conductive pastes, adhesives, lenses, transparent resin materials, three-dimensional modeling materials, cushioning materials, repair materials, pressure sensitive adhesives, sealing materials, heat insulating materials, sound absorbing materials, artificial leather materials, electronic materials, packaging materials, tires, automobile parts, fiber composite materials, hollow fibers, dialysis membranes, etc. in the fields of home appliance parts, electronics, aerospace, civil engineering and construction, automobiles, on-board applications, optical materials, medical materials, etc. The shape of the resin molded article of the present invention may be a sheet, a film such as a coating film, or a fiber.

The heat dissipating resin composition of the present invention is preferably used as a sealing material for protecting electronic parts, particularly semiconductors, from light, heat, moisture, dust, physical impacts, and the like.
The heat dissipating resin composition of the present invention is preferably used for a power device, an electromagnetic wave shield, or a heat dissipating resin substrate.

The resin composition or resin molded article of the present invention can be suitably used in the following fields. Semiconductor applications, specifically, photoresists, buffer coat films, rewiring materials, backgrinding tapes, dicing tapes, die bond films, epoxy sealants, film sealants, underfills, mold underfills, CMP slurries, CMP pads, and the manufacture of high-purity hydrogen fluoride. Display applications, specifically, polarizer protective films, surface treatment films, backlight films, QD sheets, protective films, transparent conductive films, cover sheets, back panels, foldable cover sheets, retardation films for circular polarizers, OLED substrates, OLED sealants, and OLED bank materials. Automotive applications, specifically, millimeter-wave radar-compatible decorative materials, LiDAR light sources, LiDAR interference filters, automotive lens materials, automotive OCA/OCR, HUD light sources, HUD concave mirrors and plane mirrors, intermediate films, connector terminals, and motor insulating sheets. Passive component applications, specifically aluminum electrolytic capacitors, film capacitors, multilayer ceramic capacitors, inductors, varistors, etc. Electromagnetic wave material applications, specifically electromagnetic wave shields, noise suppression shields, etc. Optical material applications, specifically light control glass and film applications, projector screen film applications, graphite sheet applications, LED phosphor material applications. Heat dissipation material applications, specifically heat dissipation metal substrates, heat dissipation resin substrates, heat dissipation sheets, phase change sheets, heat dissipation grease applications, heat dissipation gap filler applications, heat dissipation adhesive applications.

The present invention will be specifically explained below with reference to examples and comparative examples, but the present invention is not limited to the following examples. Parts in the examples are parts by weight unless otherwise specified. "Normal pressure" refers to 101.3 kPa, and "normal temperature" refers to 25°C.

[Average fiber diameter of various celluloses]
(1) When the average fiber diameter of the cellulose to be measured is expected to be several nanometers to several hundred nanometers, the average fiber diameter of the cellulose is calculated as follows.
A suitable solvent is added to the cellulose or cellulose dispersion to be measured to prepare a dispersion with a content of 0.0001% by mass, and the dispersion is dropped onto mica and dried to obtain an observation sample. The fiber height of the cellulose in the observation sample (the difference in height between the area with and without fibers) is measured using an atomic force microscope (AFM) (Digital Instrument, Nanoscope III Tapping mode AFM, probe is Nanosensors, Point Probe (NCH)). The suitable solvent is any solvent that swells the cellulose to be measured, and in the case of cellulose, water or ethanol is preferred, and in the case of modified cellulose or finely modified cellulose, DMF, MEK, toluene, etc. are preferred. In this case, 100 or more cellulose strands are extracted from a microscope image in which the cellulose can be confirmed, and the average fiber diameter is calculated from the fiber height. The average fiber length is calculated from the distance in the fiber direction. The average aspect ratio is calculated from the average fiber length/average fiber diameter, and the standard deviation is also calculated. Generally, the smallest unit of cellulose nanofibers prepared from higher plants is a 6 x 6 molecular chain packed in an approximately square shape, so the height analyzed in an AFM image can be regarded as the width of the fiber.

(2) When the average fiber diameter of the cellulose to be measured is expected to be between several hundred nanometers and several thousand micrometers, the average fiber diameter of the cellulose is calculated as follows.
A medium is added to the cellulose to be measured to prepare a dispersion having a content of 0.01% by mass. The dispersion is measured using a wet dispersion type image analysis particle size distribution meter (manufactured by Jusco International, product name: IF-3200) under the following conditions: front lens: 2x, telecentric zoom lens: 1x, image resolution: 0.835 μm/pixel, syringe inner diameter: 6515 μm, spacer thickness: 500 μm, image recognition mode: ghost, threshold: 8, analysis sample amount: 1 mL, sampling: 15%. 100 or more cellulose strands are measured, and the average ISO fiber diameter and average ISO fiber length are calculated as the average fiber diameter and average fiber length, respectively. The average aspect ratio is calculated from the average fiber length/average fiber diameter, and the standard deviation is also calculated.

[Anionic group content of various celluloses]
A 100 mL beaker is filled with 0.5 g of cellulose fiber to be measured, and ion-exchanged water or a 2/1 mixed solvent of methanol and water is added to make a total of 55 mL. 5 mL of 0.01 M aqueous sodium chloride solution is added to the beaker to prepare a dispersion. The dispersion is stirred until the cellulose fiber to be measured is sufficiently dispersed. 0.1 M hydrochloric acid is added to the dispersion to adjust the pH to 2.5 to 3, and an automatic titrator (manufactured by DKK-TOA Corporation, product name "AUT-701") is used to drop 0.05 M aqueous sodium hydroxide solution into the dispersion with a waiting time of 60 seconds, and the conductivity and pH values are measured every minute. The measurement is continued until the pH is about 11, and a conductivity curve is obtained. The sodium hydroxide titration amount is determined from this conductivity curve, and the anionic group content of the cellulose fiber to be measured is calculated by the following formula.

Anionic group content (mmol/g) = sodium hydroxide titration amount x sodium hydroxide aqueous solution concentration (0.05M) / mass of cellulose fiber to be measured (0.5g)

[Confirmation of cellulose crystal structure]
The crystal structures of various celluloses, such as raw cellulose, anion-modified cellulose, and modified cellulose, are confirmed by measurement under the following conditions using a diffractometer (manufactured by Rigaku Corporation, trade name: MiniFlexII).
Measurement pellet preparation conditions: A pressure in the range of 10 to 20 MPa is applied to the target cellulose using a tablet press to prepare smooth pellets with an area of 320 mm ² × thickness of 1 mm.
X-ray diffraction analysis conditions: step angle 0.01°, scan speed 10°/min, measurement range: diffraction angle 2θ=5 to 40°
X-ray source: Cu/Kα-radiation, tube voltage: 15kv, tube current: 30mA
Peak division conditions: After removing background noise, the peaks are fitted with a Gaussian function so that the error between 2θ=13° and 23° is within 5%.

The crystal structures of various celluloses are confirmed by measurement using the above-mentioned diffractometer under the above-mentioned conditions.
The degree of crystallinity of the cellulose I type crystal structure is calculated based on the following formula (A) using the area of the X-ray diffraction peak obtained by the above-mentioned peak division.
Cellulose I type crystallinity (%) = [I _cr / (I _cr + I _am )] × 100 (A)
(In the formula, I _cr represents the area of the diffraction peak of the lattice plane (002 plane) (diffraction angle 2θ=22-23°) in X-ray diffraction, and I _am represents the area of the diffraction peak of the amorphous portion (diffraction angle 2θ=18.5°).)

[Amount of modified group bonded and introduction rate in modified cellulose]
The amount of modified groups bonded is determined by the following IR measurement method, and the amount of bonded and the introduction rate are calculated by the following formula: Specifically, the IR measurement is performed by measuring the dried anion-modified cellulose or modified cellulose by the ATR method using an infrared absorption spectrometer (IR) (manufactured by Thermo Fisher Scientific, product name: Nicolet 6700), and the amount of modified groups bonded and the introduction rate are calculated by the following formulas A and B.
<Formula A>
Amount of modified group bonded (mmol/g)=a×(b−c)÷d
a: Carboxy group content of oxidized cellulose (mmol/g)
b: Peak intensity at 1720 cm ⁻¹ of oxidized cellulose c: Peak intensity at 1720 cm ⁻¹ of modified cellulose d: Peak intensity at 1720 cm ⁻¹ of oxidized cellulose Peak intensity at 1720 cm ⁻¹ : Peak intensity derived from the carbonyl group of carboxylic acid <Formula B>
Modification group introduction rate (mol%)=100×e/f
e: Amount of modified group bound (mmol/g)
f: Carboxy group content of oxidized cellulose (mmol/g)

[Cellulose content (equivalent amount) in modified cellulose]
The cellulose amount (equivalent amount) in the modified cellulose is the amount of cellulose in the modified cellulose excluding the modifying group. In the modified cellulose of the present invention, the formula weight of the modifying group may be considerably larger (for example, larger than the molecular weight of glucose), so in this specification, when it is appropriate to describe the modified cellulose without considering the difference in the formula weight of the modifying group, the amount of cellulose constituting the modified cellulose is expressed as the amount (equivalent amount) of the cellulose, not the amount of the modified cellulose.

The amount of cellulose (converted amount) is measured by the following method.
(a) When one type of “modifying compound” is added, the amount of cellulose (equivalent amount) is calculated by the following formula E.
<Formula E>: Amount of cellulose (converted amount) (g) = mass of modified cellulose (g) / [1 + molecular weight of modifying compound (g/mol) × bond amount of modifying group (mmol/g) × 0.001]
(b) When two or more types of "modifying compounds" are added, the amount of cellulose (equivalent amount) is calculated taking into account the molar ratio of each compound (i.e., the molar ratio when the total molar amount of the modifying compounds added is taken as 1).

[Production of anionically modified cellulose]
Production Example 1
Bleached coniferous kraft pulp (West Fraser, product name: Hinton) was used as the natural cellulose. A commercially available product (ALDRICH, free radical, 98% by mass) was used as the TEMPO. A commercially available product (Wako Pure Chemical Industries, 10.5% by mass aqueous solution) was used as the sodium hypochlorite. A commercially available product (Wako Pure Chemical Industries, 10.5% by mass aqueous solution) was used as the sodium bromide.

First, 10 g of the bleached kraft pulp was thoroughly stirred with 990 g of ion-exchanged water, and then 0.13 g of TEMPO, 1.3 g of sodium bromide, and 27 g of a 10.5% by mass aqueous solution of sodium hypochlorite were added in this order to the 10 g of pulp. Using a pH stat titration with an automatic titrator (manufactured by DKK-TOA Corporation, product name: AUT-701), a 0.5 M aqueous solution of sodium hydroxide was added dropwise to maintain the pH at 10.5. After the reaction was carried out for 120 minutes (20°C) at a stirring speed of 200 rpm, the addition of sodium hydroxide was stopped, and an anion-modified cellulose in which the anionic group was a carboxy group was obtained.

The anion-modified cellulose was neutralized with 0.01 M hydrochloric acid, and then thoroughly washed with ion-exchanged water until the electrical conductivity of the filtrate measured with a compact electrical conductivity meter (HORIBA, LAQUAtwin EC-33B) was 200 μs/cm or less, and then dehydrated. The carboxyl group content of the anion-modified cellulose was 1.3 mmol/g.

[Production of heat dissipating resin composition]
Production Example 2
A predetermined amount of the anion-modified cellulose finally obtained in Production Example 1 (i.e., 10 g in terms of cellulose), 470 g of acetone, and 6.5 g of Jeffamine M2070 were mixed and stirred at 25°C for 1 hour. Then, 470 g of epoxy resin jER828 (manufactured by Mitsubishi Chemical Corporation) was added and stirred at 25°C for another 1 hour. The resulting mixture was subjected to dispersion treatment at 150 MPa for 5 passes using a high-pressure homogenizer (manufactured by Yoshida Kikai Co., Ltd., Nanovater L-ES). The solvent was removed from the resulting dispersion to obtain a heat-dissipating resin composition containing modified cellulose and resin. The resulting modified cellulose had a bond amount of modifying groups of 0.34 mmol/g, a modification group introduction rate of 26 mol%, and a cellulose I-type crystallinity of 65%.

Production Example 3
50 g of the heat dissipating resin composition obtained in Production Example 2 and 50 g of jER828 were mixed and stirred at 60° C. for 30 minutes to obtain a heat dissipating resin composition containing modified cellulose and a resin.

Production Example 4
25 g of the heat dissipating resin composition obtained in Production Example 2 and 75 g of jER828 were mixed and stirred at 60° C. for 30 minutes to obtain a heat dissipating resin composition containing modified cellulose and a resin.

The properties of the modified cellulose in the above manufacturing example and the composition of the heat dissipating resin composition (mass % and volume % of each component) are summarized in Table 1. In Table 1, the numbers in parentheses are the volume % of the modified cellulose and the resin, respectively.

[Production of resin molded body]
Example 1
2.32 g of 2-ethyl-4-methyl-imidazole was added as a curing agent to 80 g of the heat dissipating resin composition obtained in Production Example 2, and the mixture was stirred for 2 minutes and degassed for 2 minutes at room temperature using an automatic revolution type mixer (Thinky Corporation, Awatori Rentaro). The mixture was then poured into a casting mold and heated in a hot air circulating oven at 60°C for 4 hours, and then further heated at 150°C for 4 hours to heat cure the mixture, producing a resin molded product. The casting mold used here was made by stacking two aluminum plates (3 mm thick) measuring 200 mm in length and 200 mm in width with a φ3 mm silicone rubber spacer and fixing them with clips.

Example 2
A resin molded article was produced by carrying out the same process as in Example 1, except that the heat dissipating resin composition obtained in Production Example 3 was used and the amount of 2-ethyl-4-methyl-imidazole was changed to 2.36 g.

Example 3
A resin molded article was produced by carrying out the same process as in Example 1, except that the heat dissipating resin composition obtained in Production Example 4 was used and the amount of 2-ethyl-4-methyl-imidazole was changed to 2.38 g.

Comparative Example 1
A resin molded body was produced by carrying out the same process as in Example 1, except that jER828 was used instead of the heat dissipating resin composition obtained in Production Example 2 and the amount of 2-ethyl-4-methyl-imidazole was changed to 2.40 g.

Test Example 1 (Evaluation of heat dissipation properties of resin molded body: Measurement of thermal conductivity of resin molded body)
The resin molded bodies obtained in each of the Examples and Comparative Examples were machined to a size of 10 mm x 80 mm and subjected to testing.
The thermal conductivity of the resin molded body was measured as an evaluation of the heat dissipation of the resin molded body. The thermal conductivity of the resin molded body was measured at 23°C using a hot disk method thermal property measuring device (TPS2500, manufactured by Kyoto Electronics Manufacturing Co., Ltd.). Three points were measured per resin molded body, and the average value was used. The results are shown in Table 2 and FIG. 1.

From Table 2 and Figure 1, which summarizes the data in Table 2, it can be seen that by increasing the amount of modified cellulose in the composition, the thermal conductivity of the resin molded body is increased, i.e., high heat dissipation properties are achieved.

The resin molded articles obtained by molding the heat dissipating resin composition of the present invention can be suitably used in fields such as home appliance parts, electronics, aerospace, civil engineering and construction, automobiles, in-vehicle applications, passive parts, and electromagnetic wave materials.

Claims (9)

A heat dissipating resin composition containing modified cellulose and a resin ,
The content of modified cellulose in the heat dissipating resin composition is 0.2% by volume or more, and the content of resin is 99.5% by volume or less,
The modified cellulose is a modified cellulose obtained by selectively converting the group at the C6 position of the glucose unit constituting the cellulose to a carboxy group of the oxidized cellulose, to which a modifying group is bonded.
Heat dissipating resin composition . The heat dissipating resin composition according to claim 1, wherein the modified cellulose has a cellulose I type crystal structure. The heat dissipating resin composition according to claim 1 or 2, wherein the average fiber diameter of the modified cellulose is 1 nm or more and 300 nm or less. The heat dissipating resin composition according to any one of claims 1 to 3 , wherein the modifying group is bonded to the carboxyl group via an ionic bond and/or a covalent bond. The heat dissipating resin composition according to any one of claims 1 to 4 , wherein the resin content is 20% by volume or more and 99.5% by volume or less. The heat dissipating resin composition according to any one of claims 1 to 5 , further comprising inorganic particles. A resin molded product obtained by molding the heat dissipating resin composition according to any one of claims 1 to 6 . The heat dissipating resin composition according to any one of claims 1 to 6 , which is for use in a power device, an electromagnetic wave shield, a heat dissipating resin substrate, or a sealing material. The resin molded article according to claim 7, which is used for a resin molding material, an electrical insulating material, a paint, an ink, a coating agent, a conductive paste, an adhesive, a lens, a transparent resin material, a three-dimensional modeling material, a cushioning material, a repair material, a pressure-sensitive adhesive, a sealing material, a heat insulating material, a sound absorbing material, an artificial leather material, an electronic material, a packaging material, a tire, an automobile part, a fiber composite material, a hollow fiber, or a dialysis membrane.

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