adhesive composition

Abstract

To provide an adhesive composition having excellent mechanical strength (for example, shear adhesion strength) and a bonding method.SOLUTION: An adhesive composition contains (a) a modified cellulose fiber having a cellulose I-type crystal structure, an average fiber length of 1000 nm or less, and an average fiber diameter of 1 nm or more and 300 nm or less, and (b) a resin. There is also provided a bonding method for bonding a structure with an adhesive composition containing (a) a modified cellulose fiber having a cellulose I-type crystal structure, an average fiber length of 1000 nm or less, and an average fiber diameter of 1 nm or more and 300 nm or less, and (b) a resin.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an adhesive composition and a bonding method. [Background technology]

[0002] In recent years, environmentally friendly technologies have been attracting attention, and against this technological background, materials using cellulose fibers, which are naturally occurring biomass, have been attracting attention.

[0003] For example, Patent Document 1 discloses an adhesive composition containing a water-insoluble resin and fine cellulose fibers containing ionic groups and / or a fine cellulose fiber composite formed by bonding modified groups to fine cellulose fibers containing ionic groups. Furthermore, Patent Document 2 discloses an adhesive composition characterized by containing fine fibrous cellulose and a matrix resin that satisfy the following conditions (A) to (E). (A) Number average fiber diameter is 2 nm or more and 500 nm or less (B) Average aspect ratio is between 10 and 1000 (C) Cellulose type I crystal structure (D) Having an anionic functional group (E) A specific polyetheramine is bonded to some or all of the anionic functional groups described in (D). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-94388 [Patent Document 2] Japanese Patent Application Publication No. 2018-44097 Summary of the Invention [Problem to be solved by the invention]

[0005] The performance required of an adhesive (or adhesive composition) varies depending on the physical properties of the object to be adhered.

[0006] The present invention relates to providing an adhesive composition and bonding method that exhibit excellent mechanical strength (for example, shear adhesive strength) when used on metal members of structures, etc. [Means for solving the problem]

[0007] The present invention relates to the following [1] to [3]. [1] Modified cellulose fibers having a cellulose type I crystalline structure, an average fiber length of 1000 nm or less, and an average fiber diameter of 1 nm or more and 300 nm or less; resin An adhesive composition comprising: [2] Modified cellulose fibers having a cellulose type I crystal structure, an average fiber length of 1000 nm or less, and an average fiber diameter of 1 nm or more and 300 nm or less; and resin A bonding method for bonding structures with an adhesive composition containing the above-mentioned compound. [3] Modified cellulose fibers having a cellulose type I crystal structure, an average fiber length of 1000 nm or less, and an average fiber diameter of 1 nm or more and 300 nm or less; and resin A bonding method for bonding metal members with an adhesive composition containing the above-mentioned compound. [Effects of the Invention]

[0008] According to the present invention, an adhesive composition and a bonding method are provided that are excellent in mechanical strength (for example, shear adhesive strength). DETAILED DESCRIPTION OF THE INVENTION

[0009] Although the detailed mechanism by which the adhesive composition of the present invention exerts such effects is unknown, it is presumed that the presence of the modified cellulose fiber at the interface between the object to be bonded and the resin improves the adhesion of the resin to the bonding surface, even if the bonding surface of the object to be bonded (e.g., metal and / or plastic) is somewhat less smooth, thereby improving the mechanical strength. This is presumed to be because the adhesive composition of the present invention suppresses thermal shrinkage during bonding.

[0010] The adhesive composition of the present invention comprises: A modified cellulose fiber having a cellulose type I crystal structure, an average fiber length of 1000 nm or less, and an average fiber diameter of 1 nm or more and 300 nm or less; and resin Contains:

[0011] [Modified cellulose fiber] The modified cellulose fibers of the present invention are cellulose fibers having a cellulose type I crystalline structure, an average fiber length of 1000 nm or less, and an average fiber diameter of 1 nm to 300 nm, and are obtained by bonding modifying groups to the cellulose fibers. The modifying groups are preferably bonded to some or all of the hydroxy groups of the cellulose fibers, or to carboxy groups obtained by converting the group (—CHOH) at the C6 position of the glucose unit to a carboxy group.

[0012] The modifying group preferably contains one or more selected from the group consisting of (a) a hydrocarbon group, (b) a silicone chain, and (c) an alkylene oxide chain. Furthermore, the cellulose fiber to which the modifying group is bonded is preferably anion-modified cellulose fiber from the viewpoint of ease of bonding of the modifying group.

[0013] (anion-modified cellulose fiber) Anion-modified cellulose fibers are cellulose fibers having anionic groups, such as one or more groups selected from the group consisting of carboxyl groups, (phosphite) groups, and sulfonic acid groups, in the molecule. Introduction of anionic groups into cellulose fibers can be achieved by the methods described below. From the standpoints of availability and effectiveness, anion-modified cellulose fibers having carboxyl groups as anionic groups are preferred, and anion-modified cellulose fibers in which the group (—CHOH) at the C6 position of the glucose unit constituting the cellulose fiber has been selectively converted to a carboxyl group (referred to as “oxidized cellulose fibers”) are more preferred. The counter ion of the anionic group is preferably a proton.

[0014] The anionic group content of the anion-modified cellulose fiber is preferably 0.1 mmol / g or more, more preferably 0.4 mmol / g or more, even more preferably 0.6 mmol / g or more, even more preferably 0.7 mmol / g or more, and even more preferably 0.8 mmol / g or more, from the viewpoint of introducing stable modifying groups and increasing adhesive strength through the introduction of modifying groups. Furthermore, from the viewpoint of improving handleability, the anionic group content is preferably 3 mmol / g or less, more preferably 2.5 mmol / g or less, more preferably 2 mmol / g or less, more preferably 1.9 mmol / g or less, even more preferably 1.8 mmol / g or less, more preferably 1.7 mmol / g or less, and even more preferably 1.5 mmol / g or less. The term "anionic group content" refers to the total amount of anionic groups in the glucose constituting the cellulose fiber, and is specifically measured by the method described in the Examples below.

[0015] The term "modifying groups bonded to anionic groups of anion-modified cellulose fibers" means that the modifying groups are bonded to anionic groups, preferably carboxy groups, possessed by the anion-modified cellulose fibers. The bond between the modifying groups and the anionic groups can be an ionic bond and / or a covalent bond. Examples of covalent bonds include amide bonds, ester bonds, and urethane bonds, with amide bonds being preferred.

[0016] (modifying group) The modifying groups include (a) hydrocarbon groups, (b) silicone chains, and (c) alkylene oxide chains. These modifying groups may be bonded (introduced) to cellulose fibers either alone or in combination.

[0017] (a) Hydrocarbon group The hydrocarbon group includes monovalent hydrocarbon groups, for example, chain saturated hydrocarbon groups, chain unsaturated hydrocarbon groups, cyclic saturated hydrocarbon groups, and (heterocyclic) aromatic hydrocarbon groups. From the viewpoint of increasing adhesive strength, the number of carbon atoms in the hydrocarbon group is 1 or more, preferably 3 or more, more preferably 8 or more, and even more preferably 10 or more, and from the same viewpoint, is preferably 30 or less, more preferably 22 or less, and even more preferably 18 or less. The hydrocarbon group may have a substituent as described below, and a portion of the hydrocarbon group may be substituted with a hydrogen nitride group.

[0018] The chain saturated hydrocarbon group is preferably one having 3 to 30 carbon atoms, and specific examples include a propyl group, an isopropyl group, a butyl group, a sec-butyl group, a tert-butyl group, an isobutyl group, a pentyl group, a tert-pentyl group, an isopentyl group, a hexyl group, an isohexyl group, a heptyl group, an octyl group, a 2-ethylhexyl group, a nonyl group, a decyl group, a dodecyl group, a tridecyl group, a tetradecyl group, an octadecyl group, a docosyl group, and an octacosanyl group.

[0019] The chain unsaturated hydrocarbon group is preferably one having 3 to 30 carbon atoms, and specific examples include a propenyl group, a butenyl group, an isobutenyl group, an isoprenyl group, a pentenyl group, a hexenyl group, a heptenyl group, an octenyl group, a nonenyl group, a decenyl group, a dodecenyl group, a tridecenyl group, a tetradecenyl group, and an octadecenyl group.

[0020] The cyclic saturated hydrocarbon group is preferably one having 3 to 20 carbon atoms, 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.

[0021] Examples of aromatic hydrocarbon groups include aryl groups and aralkyl groups. The aryl groups and aralkyl groups may be unsubstituted or substituted with the substituents described below. The heterocyclic aromatic hydrocarbon group includes an imidazole group.

[0022] 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 the substituents described below.

[0023] The total number of carbon atoms in the aralkyl group is preferably 7 or more and 24 or less, and specific examples of the aralkyl group include a benzyl group, a phenethyl group, a phenylpropyl group, a phenylpentyl group, a phenylhexyl group, a phenylheptyl group, a phenyloctyl group, and groups in which these groups are substituted with the substituents described below. The total number of carbon atoms in the imidazole group is preferably 3 or more and 24 or less, and specific examples of the imidazole group include an imidazole group, a methylimidazole group, an ethylimidazole group, a propylimidazole group, a 2-phenylimidazole group, a benzimidazole group, and groups in which these groups are substituted with a substituent.

[0024] (b) Silicone chain The silicone chain is a monovalent group having a siloxane bond as the main chain, and may further include an alkylene group. The silicone chain may have a substituent, which will be described later.

[0025] (c) alkylene oxide chain The alkylene oxide chain is a structure containing a (co)polymer of ethylene oxide (EO) or propylene oxide (PO), and is preferably one or more structures selected from the group consisting of a structure containing a polymer of EO (EO chain), a structure containing a polymer of PO (PO chain), and a structure containing a copolymer in which EO and PO are polymerized randomly or in a block form ((EO / PO) chain). The alkylene oxide chain may further have a hydrocarbon group bonded thereto.

[0026] Examples of the alkylene oxide chain include those represented by the following formula:

[0027] [ka]

[0028] (In the formula, R 1 represents a hydrogen atom, a hydrocarbon group having from 1 to 6 carbon atoms, or a -CH2CH(CH3)NH2 group. EO and PO are present randomly or in a block form, a is 0 or a positive number indicating the average number of moles of EO added, and b is 0 or a positive number indicating the average number of moles of PO added, except when both a and b are 0.

[0029] In the above formula, a represents the average number of moles of EO added, and from the viewpoints of availability and affinity with the resin, it is preferably 0 or more, more preferably 1 or more, and even more preferably 2 or more; from the same viewpoints, it is preferably 100 or less, more preferably 70 or less.

[0030] In the above formula, b represents the average number of moles of PO added, and from the viewpoint of affinity with the resin, it is preferably 0 or more, more preferably 1 or more, and even more preferably 3 or more, and from the viewpoint of availability, it is preferably 50 or less, more preferably 40 or less.

[0031] R in the above formula 1Specific examples of the hydrocarbon group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, a tert-butyl group, an isobutyl group, a pentyl group, a tert-pentyl group, an isopentyl group, a hexyl group, and an isohexyl group.

[0032] The formula weight (molecular weight) of the alkylene oxide chain is preferably 500 or more, more preferably 1,000 or more, and is preferably 10,000 or less, more preferably 7,000 or less. The formula weight of the alkylene oxide chain can be determined by calculation from the average number of moles added when producing an amine compound having an alkylene oxide chain, which will be described later.

[0033] From the viewpoint of increasing adhesive strength, the PO content (mol %) in the (EO / PO) chain is preferably 1 mol % or more, more preferably 5 mol % or more, and from the same viewpoint, it is preferably 100 mol % or less, more preferably 95 mol % or less, and even more preferably 90 mol % or less. The PO content in the (EO / PO) chain can be calculated from the average number of moles added when producing an amine compound having an alkylene oxide chain, which will be described later. The alkylene oxide chain may have the following substituents.

[0034] (d) Further Substituents The modifying group may further have a substituent, such as an alkoxy group having 1 to 6 carbon atoms, such as a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, a pentyloxy group, an isopentyloxy group, or a hexyloxy group; a methoxycarbonyl group, an ethoxycarbonyl group, a propoxycarbonyl group, an isopropoxycarbonyl group, a butoxycarbonyl group, an isobutoxycarbonyl group, or a sec-butoxycarbonyl group; alkoxycarbonyl groups having 1 to 6 carbon atoms, such as 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; dialkylamino groups having an alkyl group with 1 to 6 carbon atoms; and a hydroxy group.

[0035] [Method for producing modified cellulose fibers] Modified cellulose fibers can be produced, for example, by introducing anionic groups into raw cellulose fibers to produce anionically modified cellulose fibers (step 1), and then bonding modifying groups to the anionic groups of the anionically modified cellulose fibers (step 2).

[0036] (Process 1) Raw material: cellulose fiber As the cellulose fiber that is the raw material for the anion-modified cellulose fiber, natural cellulose is preferred from an environmental perspective, and examples thereof include wood pulp such as softwood pulp and hardwood pulp; cotton pulp such as cotton linter and cotton lint; non-wood pulp such as straw pulp and bagasse pulp; and bacterial cellulose, and these can be used alone or in combination of two or more.

[0037] The average fiber diameter of the raw cellulose fibers is not particularly limited, but from the viewpoints of handleability and cost, it is preferably 5 μm or more, more preferably 7 μm or more, and from the same viewpoints, it is preferably 500 μm or less, more preferably 300 μm or less. The average fiber diameter of the raw cellulose fibers is determined by the method described in the Examples below.

[0038] The average fiber length of the raw cellulose fibers 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 viewpoints, it is preferably 5,000 μm or less, more preferably 3,000 μm or less. The average fiber length of the raw cellulose fibers can be measured according to the method described in the Examples below.

[0039] Processing method (1) When carboxyl groups are introduced as anionic groups into cellulose fibers Methods for introducing carboxy groups into cellulose fibers include, for example, a method of oxidizing the hydroxy groups of the cellulose fibers to convert them into carboxy groups, and a method of reacting the hydroxy groups of the cellulose fibers with at least one selected from the group consisting of compounds having carboxy groups, acid anhydrides of compounds having carboxy groups, and derivatives thereof.

[0040] Examples of methods for oxidizing the hydroxy groups of cellulose fibers include those described in JP 2015-143336 and JP 2015-143337, which involve reacting raw cellulose fibers with an oxidizing agent such as sodium hypochlorite and a bromide such as sodium bromide using 2,2,6,6-tetramethyl-1-piperidine-N-oxyl (TEMPO) as a catalyst. By oxidizing cellulose fibers using TEMPO as a catalyst, the group at C6 of the glucose of the cellulose fiber structural unit is selectively converted to a carboxy group, thereby producing the oxidized cellulose fibers described above.

[0041] The compound having a carboxy group to be used for introducing a carboxy group into cellulose fibers is not particularly limited, but specific examples include halogenated acetic acids, such as chloroacetic acid. The acid anhydrides of compounds having a carboxyl group and their derivatives to be used for introducing a carboxyl group into cellulose fibers 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.

[0042] (2) When sulfonic acid groups or (phosphorous) groups are introduced as anionic groups into cellulose fibers As a method for introducing sulfonic acid groups into cellulose fibers, a method of adding sulfuric acid to cellulose fibers and heating the fibers can be given. Methods for introducing (phosphite) groups into cellulose fibers include mixing a powder or aqueous solution of (phosphite) phosphorous or a (phosphite) derivative with dry or wet cellulose fibers, or adding an aqueous solution of (phosphite) phosphorous or a (phosphite) derivative to a dispersion of cellulose fibers. When these methods are employed, dehydration treatment, heat treatment, etc. are generally carried out after mixing or adding a powder or aqueous solution of (phosphite) phosphorous or a (phosphite) derivative.

[0043] (Process 2) Introduction of modifying groups into the anionic groups of anion-modified cellulose fibers is achieved by reacting the anion-modified cellulose fibers with a compound for introducing modifying groups into the anionic groups (referred to as a "modifying compound"). Methods for introducing modifying groups include (1) JP 2015-143336 A when introducing via an ionic bond, and (2) JP 2015-143337 A when introducing via an amide bond. After completion of step 2, post-treatment may be carried out as appropriate to remove unreacted compounds, etc. Examples of post-treatment methods that can be used include filtration, centrifugation, dialysis, etc.

[0044] (1) Introduction via ionic bond When the modifying group is introduced via an ionic bond, the anion-modified cellulose fiber and the modifying compound are mixed, and an ionic bond is formed between the anionic group contained in the anion-modified cellulose fiber and the amino group of the modifying compound. Specifically, when oxidized cellulose fibers are used as the anion-modified cellulose fibers and a primary amine having the aforementioned modifying group is used as the modifying compound, the aforementioned modifying group can be introduced via an ionic bond to the carboxy group at the C6 position of the glucose constituting the cellulose fibers, as shown in the following formula (where C 6 is the carbon atom at the 6th position of the glucose that makes up the cellulose fiber, and R is a modifying group.

[0045] [ka]

[0046] Compound for modification The modifying compound used in this embodiment may be any compound capable of introducing a desired modifying group, and preferred examples include the above-mentioned amine compounds having a hydrocarbon group, an alkylene oxide chain, or a silicone chain, phosphonium compounds, and guanidino group-containing compounds.

[0047] Amine compounds The amine compound is, for example, an amine compound having the aforementioned hydrocarbon group, the aforementioned alkylene oxide chain, or the aforementioned silicone chain as a modifying group, and such hydrocarbon group or the like is introduced into the anion-modified cellulose fiber via an ionic bond to become the modifying group in the modified cellulose fiber.

[0048] The amine compound may be any of primary amines, secondary amines, tertiary amines, and quaternary ammonium compounds. From the viewpoint of reactivity, preferred anion components of the quaternary ammonium compounds include halogen ions such as chloride ions and bromide ions, hydrogen sulfate ions, perchlorate ions, tetrafluoroborate ions, hexafluorophosphate ions, trifluoromethanesulfonate ions, and hydroxy ions.

[0049] Amine compounds having hydrocarbon groups Specific examples of amine compounds having a hydrocarbon group include primary to 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, benzylamine, naphthylamine, imidazole, 2-methylimidazole, 2-ethylimidazole, 2-phenylimidazole, 2-ethyl-4-methylimidazole, 2-phenyl-4-methylimidazole, and 1-(3-aminopropyl)imidazole.

[0050] 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.

[0051] The amine compound having a hydrocarbon group may be a commercially available product or may be prepared according to a known method.

[0052] Amine compounds having alkylene oxide chains In the amine compound, the alkylene oxide chain 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 includes an alkylene group having preferably 1 to 6 carbon atoms, more preferably 1 to 3 carbon atoms. Preferred examples of such alkylene groups include ethylene and propylene groups.

[0053] Examples of the amine having an alkylene oxide chain include amines represented by the following formula (i):

[0054] [ka]

[0055] In formula (i), R 1 , a and b are R in the formula showing an example of the alkylene oxide chain. 1 , a and b.

[0056] Amine compounds having alkylene oxide chains can be prepared according to known methods. For example, desired amounts of ethylene oxide and propylene oxide can be added to a propylene glycol alkyl ether, followed by aminating the hydroxyl group terminal. If necessary, the alkyl ether can be cleaved with an acid to convert the terminal to a hydrogen atom. For these production methods, see JP-A-3-181448, and details of such amine compounds are described, for example, in JP-A-6105139.

[0057] As the amine compound having an alkylene oxide chain, for example, commercially available products can be suitably used. Specific examples 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-900, Jeffamine ED-2003, Jeffamine D-2000, Jeffamine D-4000, XTJ-510, Jeffamine T-3000, and Jeffamine ED-2003, all manufactured by HUNTSMAN. Examples include T-5000, XTJ-502, XTJ-509, and XTJ-510, and SUNBRIGHT MEPA-10H, SUNBRIGHT MEPA-20H, SUNBRIGHT MEPA-50H, SUNBRIGHT MEPA-10T, SUNBRIGHT MEPA-12T, SUNBRIGHT MEPA-20T, SUNBRIGHT MEPA-30T, and SUNBRIGHT MEPA-40T manufactured by NOF Corporation. These may be used alone or in combination of two or more.

[0058] Amine compounds with silicone chains Examples of such amine compounds include those having a structure in which an amino group is bonded to a silicone chain skeleton via an alkylene group or the like. In this specification, such amine compounds may be referred to as "amino-modified silicones." The amino-modified silicones may be commercially available products or may be prepared according to known methods. Only one type of amino-modified silicone may be used, or two or more types may be used.

[0059] As amino-modified silicones, from the viewpoint of performance, the following products are recommended: TSF4703 (kinematic viscosity: 1000, amino equivalent: 1600) and TSF4708 (kinematic viscosity: 1000, amino equivalent: 2800) manufactured by Momentive Performance Materials, SS-3551 (kinematic viscosity: 1000, amino equivalent: 1600), SF8457C (kinematic viscosity: 1200, amino equivalent: 1800), SF8417 (kinematic viscosity: 1200, amino equivalent: 1700), BY16-209 (kinematic viscosity: 500, amino equivalent: 1800), and B Preferred examples include Y16-892 (kinematic viscosity: 1500, amino equivalent: 2000), BY16-898 (kinematic viscosity: 2000, amino equivalent: 2900), FZ-3760 (kinematic viscosity: 220, amino equivalent: 1600), KF8002 (kinematic viscosity: 1100, amino equivalent: 1700), KF867 (kinematic viscosity: 1300, amino equivalent: 1700), KF-864 (kinematic viscosity: 1700, amino equivalent: 3800), BY16-213 (kinematic viscosity: 55, amino equivalent: 2700), and BY16-853U (kinematic viscosity: 14, amino equivalent: 450), all manufactured by Shin-Etsu Chemical Co., Ltd. Kinematic viscosity is measured at 25°C (unit: mm 2 / s), and the unit of amino equivalent is g / mol.

[0060] Guanidino group-containing compounds The guanidino group-containing compound is, for example, a guanidine compound having the aforementioned hydrocarbon group, silicone chain, or alkylene oxide chain as a modifying group, and such hydrocarbon group or the like is introduced into the anion-modified cellulose fiber via an ionic bond to become the modifying group in the modified cellulose fiber. Examples of the guanidino group-containing compound include diphenylguanidine, ditolylguanidine, 1,2,3-triphenylguanidine, aminoguanidine, and arginine.

[0061] Reaction conditions etc. The amount of modifying compound used is, from the standpoint of reactivity, preferably an amount such that the number of amino groups in the modifying compound is 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 fiber, and, from the standpoint of product purity, 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.

[0062] It is preferable to use a solvent when mixing. As the solvent, it is preferable to select a solvent in which the compound to be used dissolves, and examples thereof 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, 1-methoxy-2-propanol (PGME), water, etc., and these can be used alone or in combination of two or more.

[0063] 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 the reactivity of the compound. Furthermore, from the viewpoint of suppressing discoloration of the modified cellulose fiber, it 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 appropriately set depending on the type of compound and solvent used, but from the viewpoint of the reactivity of the compound, it is preferably 0.01 hour or higher, more preferably 0.1 hour or higher, and from the viewpoint of productivity, it is preferably 48 hours or lower, more preferably 24 hours or lower.

[0064] (2) Introduction via an amide bond When the modifying group is introduced via an amide bond, the anion-modified cellulose fiber and the modifying compound are mixed in the presence of a known condensing agent, whereby an amide bond is formed between the anionic group contained in the anion-modified cellulose fiber and the amino group of the modifying compound. Specifically, when oxidized cellulose fibers are used as the anion-modified cellulose fibers and a primary amine having the aforementioned modifying group is used as the modifying compound, the aforementioned modifying group can be introduced via an amide bond to the carboxy group at the C6 position of the glucose constituting the cellulose fibers, as shown in the following formula (wherein: C 6 is the carbon atom at the 6th position of the glucose that makes up the cellulose fiber, and R is a modifying group.

[0065] [ka]

[0066] Compound for modification The modifying compound used in this embodiment may be any compound capable of introducing a desired modifying group, and preferred examples include the above-mentioned amine compounds having a hydrocarbon group, an alkylene oxide chain, or a silicone chain.

[0067] Amine compounds The amine compound is, for example, an amine compound having the aforementioned hydrocarbon group, the aforementioned alkylene oxide chain, or the aforementioned silicone chain as a modifying group, and such a hydrocarbon group or the like is introduced into the anion-modified cellulose fiber via an amide bond to become a modifying group in the modified cellulose fiber.

[0068] Examples of the amine compound include primary amines and secondary amines. Specific examples of the amine compound include primary amines and secondary amines among amine compounds having a hydrocarbon group, amine compounds having an alkylene oxide chain, and amine compounds having a silicone chain, which are exemplified in the above-mentioned "(1) Aspect of introduction via ionic bond."

[0069] Reaction conditions The amount of modifying compound used is, from the viewpoint of enhancing reactivity and adhesive strength, an amount such that the amount of amino groups in the modifying compound is preferably 0.05 mol or more, more preferably 0.1 mol or more, even more preferably 0.2 mol or more, even more preferably 0.3 mol or more, and even more preferably 0.5 mol or more per mol of carboxy groups in the oxidized cellulose fibers, and, from the viewpoint of product purity and dischargeability, an amount such that the amount 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.

[0070] The condensing 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"). It is also possible to carry out the reaction by heat treatment alone without using a condensing agent.

[0071] A solvent may or may not be used in the amidation reaction. When a solvent is used, it is preferable to select a solvent that dissolves the compound to be used. Specific examples of the solvent include the solvents exemplified in the above-mentioned "(1) Mode of introduction via ionic bond."

[0072] The reaction time and reaction temperature in the amidation reaction can be appropriately selected depending on the type of compound and solvent used, etc., but from the viewpoint of the reaction rate, they are 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, the reaction temperature is preferably 200°C or lower, more preferably 80°C or lower, and even more preferably 30°C or lower.

[0073] (Refining process) By micronizing the cellulose fibers at any stage of the production method of the modified cellulose fibers (for example, before step 1, before step 2, and after step 2), it is possible to micronize the cellulose fibers from the micrometer scale to the nanometer scale. Reducing the average fiber diameter to the nanometer size is preferable because it improves dispersibility in the resin.

[0074] The micronization treatment can be carried out by a known micronization treatment method. For example, to obtain modified cellulose fibers having an average fiber diameter of nanometer size, a treatment method using a grinder such as a mass colloider or a treatment method using a high-pressure homogenizer in a medium may be carried out.

[0075] Examples of the medium include alcohols having 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms, such as water, methanol, ethanol, propanol, and 1-methoxy-2-propanol (PGME); 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 dimethyl sulfoxide. These solvents can be used alone or in combination. The amount of the medium used should be an effective amount for dispersing the modified cellulose fibers. The amount used is preferably at least 1 times, more preferably at least 2 times, and preferably at most 500 times, more preferably at most 200 times the mass of the modified cellulose fibers.

[0076] As the apparatus used in the micronization treatment, in addition to a high-pressure homogenizer, known dispersers are also 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 fiber in the micronization treatment is preferably 50 mass% or less.

[0077] [Properties of modified cellulose fibers] The main properties of the modified cellulose fiber of the present invention are as follows:

[0078] (crystal structure) The modified cellulose fiber has a cellulose type I crystal structure from the viewpoint of enhancing adhesive strength. The crystallinity of the modified cellulose fiber is preferably 10% or more, more preferably 15% or more, and even more preferably 20% or more from the viewpoint of enhancing adhesive strength. Furthermore, 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 the cellulose fiber refers to the cellulose type I crystallinity calculated from the diffraction intensity value by X-ray diffraction, and can be measured according to the method described in the Examples below. Cellulose type I refers to the crystalline form of native cellulose, and cellulose type I crystallinity refers to the proportion of crystalline regions in the entire cellulose fiber. The presence or absence of the cellulose type I crystal structure can be determined by the presence of a peak at 2θ = 22.6° in X-ray diffraction measurement.

[0079] (average fiber diameter) The modified cellulose fibers are preferably those that have been subjected to a micronization treatment to nanometer size. Therefore, the average fiber diameter of the modified cellulose fibers is preferably 1 nm or more, more preferably 2 nm or more, from the viewpoints of handleability, availability, and cost, and is preferably 300 nm or less, more preferably 200 nm or less, even more preferably 150 nm or less, even more preferably 120 nm or less, and even more preferably 20 nm or less, from the viewpoints of improving handleability, dispersibility, and adhesive strength.

[0080] (average fiber length) The average fiber length of the modified cellulose fiber is preferably 10 nm or more, more preferably 30 nm or more, and even more preferably 50 nm or more, from the viewpoint of increasing adhesive strength, while it is 1000 nm or less, preferably 500 nm or less, more preferably 300 nm or less, and even more preferably less than 150 nm, from the viewpoint of increasing dischargeability and adhesive strength.

[0081] (average aspect ratio) The average aspect ratio of the modified cellulose fiber is preferably 5 or more, more preferably 10 or more, and even more preferably 20 or more from the viewpoint of increasing adhesive strength, while it is preferably 300 or less, more preferably 200 or less, even more preferably 150 or less, even more preferably 100 or less, and even more preferably 70 or less from the viewpoint of increasing dischargeability and adhesive strength. By setting the average fiber length and average aspect ratio within the above ranges, excellent adhesion is achieved between materials with different physical properties (for example, materials with different linear expansion coefficients). The average fiber diameter, average fiber length and average aspect ratio of the modified cellulose fiber can be determined by the method described in the Examples below.

[0082] (Amount of modified group bonded and introduction rate) The amount of modifying groups bonded to the modified cellulose fiber is preferably 0.01 mmol / g or more from the viewpoint of increasing adhesive strength, and from the same viewpoint, is preferably 3.0 mmol / g or less. When any two or more types of modifying groups are simultaneously introduced into the modified cellulose fiber, the amount of modifying groups bonded is preferably within the above range.

[0083] From the viewpoint of dispersibility, the introduction rate of the modifying group in the modified cellulose fiber is preferably 10 mol% or more, the higher the better, and 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 be within the above range as long as it does not exceed the upper limit of 100 mol%.

[0084] The bonded amount and introduction rate of the modifying group 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 bonded amount (mmol / g) and introduction rate (mol%) of the modifying group refer to the amount and rate of the modifying group introduced (bonded) to the anionic group in the modified cellulose fiber. For example, when the anionic group is a carboxy group, the bonded amount and introduction rate of the modifying group in the modified cellulose fiber are calculated by the method described in the Examples below.

[0085] The amount of modified cellulose fiber in the composition of the present invention, calculated in terms of cellulose (excluding modifying groups, etc.), is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, more preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and even more preferably 0.5% by mass or more, from the viewpoint of increasing adhesive strength, while from the viewpoint of ejection property, it is preferably 30% by mass or less, more preferably 20% by mass or less, more preferably 15% by mass or less, more preferably 10% by mass or less, more preferably 7% by mass or less, even more preferably 5% by mass or less, and even more preferably 3% by mass or less.

[0086] 〔resin〕 In view of the use of the resin in various structures, the resin in the present invention is preferably a water-insoluble resin that does not dissolve in water or has extremely low solubility in water. Specifically, a resin whose solubility in water at 25°C is 1 mg or less per 100 g of water is called a water-insoluble resin.

[0087] The solubility is measured as follows. 100 mg of resin is added to 1 L of water (25°C) and stirred for 24 hours using a stirring device such as a stirrer. The solution (or suspension) is then centrifuged at 25°C and 3000 x g for 30 minutes to collect the insoluble residue. This residue is dried at 105°C for 3 days, and the mass after drying (dry mass) is measured. Resins with a dry mass of less than 99 mg are considered water-soluble, and those with a dry mass of 99 mg or more are considered water-insoluble.

[0088] The resin used in the present invention is preferably a resin that has adhesiveness by itself or a resin that exhibits adhesiveness when used in combination with a curing agent. The resin may be used alone or as a mixture of two or more resins.

[0089] Specific examples of the resin include epoxy resin, urethane resin, acrylic resin, vinyl chloride resin, phenoxy resin, phenol resin, urea resin, melamine resin, polyimide resin, unsaturated polyester resin, diallyl phthalate resin, and rubber-based resin.

[0090] Among the resins, curable resins (e.g., epoxy resin, urethane resin, acrylic resin, phenoxy resin, phenolic resin, urea resin, melamine resin) are preferred from the viewpoint of increasing adhesive strength. Depending on the type of resin, photocuring and / or heat curing treatment can be performed. Thermosetting resins are preferred as the resin used in the present invention.

[0091] The mass ratio of modified cellulose fiber / resin in the composition of the present invention, calculated in terms of cellulose (excluding modifying groups, etc.) (however, if the cellulose has anionic groups, calculated in terms of anion-modified cellulose), is preferably 0.01 / 100 or more, more preferably 0.05 / 100 or more, more preferably 0.1 / 100 or more, more preferably 0.3 / 100 or more, and even more preferably 0.5 / 100 or more, from the viewpoint of increasing adhesive strength; on the other hand, from the viewpoint of dischargeability, it is preferably 30 / 100 or less, more preferably 20 / 100 or less, more preferably 15 / 100 or less, more preferably 10 / 100 or less, more preferably 7 / 100 or less, even more preferably 5 / 100 or less, and even more preferably 3 / 100 or less.

[0092] [Other ingredients] The adhesive composition of the present invention may contain, as necessary, components known in the adhesive field, such as a polymerization initiator, a plasticizer, a stabilizer, a lubricant, a surfactant, etc. The amounts of such components are not particularly limited, and appropriate amounts may be used as appropriate.

[0093] [Method for producing adhesive composition] The adhesive composition of the present invention can be produced, for example, by mixing the modified cellulose fiber with the resin, etc. If necessary, a solvent, a curing agent, or other components described above can be further mixed. The method for mixing the components constituting the adhesive composition is not particularly limited, and includes common methods such as those using a stirrer, ultrasonic homogenizer, or high-pressure homogenizer.

[0094] Examples of solvents that can be used during production include dimethylformamide, ethyl acetate, methyl methacrylate, ethanol, isopropanol, N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N,N-dimethylacetamide, tetrahydrofuran (THF), a diester of succinic acid and triethylene glycol monomethyl ether, acetone, methyl ethyl ketone (MEK), acetonitrile, dichloromethane, chloroform, toluene, 1-methoxy-2-propanol (PGME), and acetic acid. These can be used alone or in combination of two or more. When a solvent is used, the amount thereof is, for example, preferably 50 parts by mass or more, more preferably 100 parts by mass or more, per 100 parts by mass of the resin, while preferably 5000 parts by mass or less, more preferably 2000 parts by mass or less.

[0095] The adhesive composition of the present invention and adhesives using the composition are in a liquid or solid form (e.g., pellets or powder) at room temperature (25°C). If the composition is solid, it can be converted into a paste, solution, or dispersion by adding an appropriate medium. Furthermore, it can be heated as needed before use to form a fluid.

[0096] <Adhesive composition and bonding method> The bonding method of the present invention comprises providing modified cellulose fibers having a cellulose type I crystalline structure, an average fiber length of 1000 nm or less, and an average fiber diameter of 1 nm or more and 300 nm or less, and resin The adhesive composition contains the above-mentioned compound (namely, the adhesive composition of the present invention).

[0097] The bonding method of the present invention includes, for example, a method of applying the adhesive composition of the present invention to a structure (or a component thereof) and bonding it to a counterpart structure (or a component thereof). Such an adhesive composition includes a structural adhesive composition.

[0098] A structural adhesive composition is an adhesive composition used in structures such as vehicles and buildings that require mechanical strength, and is preferably used to bond vehicle assemblies, replacing or reinforcing conventional joining techniques such as welding, nuts and bolts, and rivets. The adhesive composition of the present invention can be used as a structural adhesive by itself, or can be used as an adhesive material to obtain an adhesive by further blending other components.

[0099] Examples of vehicles include rockets, airplanes, drones, automobiles, ships, etc. Specifically, it is used to manufacture automobile structures by structurally bonding parts such as automobile bodies and automobile components, and is particularly suitable for bonding by a method that combines spot welding and adhesives (weld bond method).

[0100] The method for applying the adhesive composition to a structure is not particularly limited, and examples thereof include methods using a spray, a sealer gun, a dispenser, a nozzle, a brush, a spatula, etc. Among these, it is preferable to use a dispenser because the adhesive composition of the present invention has excellent dischargeability. When a dispenser is used, an embodiment in which the adhesive composition is discharged from the dispenser and applied to the structure can be mentioned.

[0101] After laminating the structure and the other structure, the structure can be completely bonded to each other by maintaining the structure at, for example, -30 to 200°C for 1 minute to 3 days.

[0102] The adhesive composition of the present invention has excellent bonding strength with a variety of materials, for example, metals such as iron, aluminum, copper, etc., alloys such as steel and aluminum alloys, plastics such as polypropylene, polyamide, polyacetal, etc., fiber-reinforced plastics such as carbon fiber-reinforced plastic and glass fiber-reinforced plastic, rubber, carbon fiber, glass, ceramics, etc., and can contribute to reducing the weight of structures such as vehicles and reducing welding costs. The adhesive composition of the present invention is preferably used for bonding metal members, and is more preferably used when the bonding surface of the metal member contains aluminum.

[0103] In the bonding method of the present invention, the surface of the structure or its component to which the adhesive composition is applied, i.e., the bonding surface, is preferably made of a material containing one or more selected from the group consisting of metal, plastic, ceramic, and glass, more preferably a material containing metal and / or plastic, and even more preferably a material containing metal. That is, the bonding method of the present invention is preferably a method in which the adhesive composition of the present invention is applied to a metal member and then the metal member is bonded to the other metal member. The metal member is a material formed from metal and is different from powder or the like.

[0104] The adhesive surface material used in the adhesive method of the present invention has a linear expansion coefficient of 20 × 10 -6 / °C or more. Examples of such metals include aluminum and zinc. Even if the adhesive of the present invention has a high linear expansion coefficient, it is presumed that the adhesive strength is high because thermal shrinkage is suppressed.

[0105] More specifically, examples of bonding surfaces for metal members include steel plates, SPC steel plates, plated steel plates (e.g., electrogalvanized steel plates, hot-dip galvanized steel plates, organic surface-treated steel plates, alloyed galvanized steel plates, zinc-nickel alloy-plated steel plates, tin-lead plated steel plates, and cationic electrodeposition-coated steel plates), aluminum plates, aluminum alloy plates (e.g., aluminum-manganese alloy plates and aluminum-magnesium alloy plates), and magnesium plates. Examples of bonding surfaces for plastics include fiber-reinforced plastic fiber plates such as carbon fiber-reinforced plastics and glass fiber-reinforced plastics. Examples of bonding surfaces for ceramics include barium titanate, boron nitride, silicon nitride, lead zirconate titanate, aluminum oxide, aluminum nitride, silicon carbide, zinc oxide, zirconia, ferrite, indium oxide, and silicon. Examples of bonding surfaces for glass include soda-lime glass, lead glass, borosilicate glass, and quartz glass. In particular, when the bonding surface of the metal member contains aluminum, the adhesive composition of the present invention and the bonding method of the present invention are suitably applied.

[0106] The adhesive composition of the present invention is particularly excellent in adhesiveness between materials with different physical properties (for example, metal materials with different linear expansion coefficients). -6 / ℃ or more with metals and 20×10 -6 / °C. Specifically, the adhesive strength is also excellent for combinations of dissimilar metals (for example, steel and aluminum alloy, i.e., metals containing iron and metals containing aluminum). Metals containing iron can be used as steel plates, and metals containing aluminum can be used as alloy plates. Therefore, the adhesive method of the present specification can also be suitably applied to methods for bonding dissimilar metals. [Example]

[0107] The present invention will be specifically described below with reference to examples. Note that the following examples are merely illustrative of the present invention and are not intended to limit the scope of the present invention. Note that "normal pressure" refers to 101.3 kPa, and "normal temperature" refers to 25°C.

[0108] [Average fiber diameter, average fiber length and average aspect ratio of anion-modified cellulose fibers and modified cellulose fibers] Water is added to the cellulose fibers to be measured to prepare a dispersion with a cellulose content of 0.0001% by mass. The dispersion is dropped onto mica and dried to serve as an observation sample. An atomic force microscope (AFM) (Nanoscope II Tapping mode AFM manufactured by Digital Instruments; the probe used is Point Probe (NCH) manufactured by Nanosensors) is used to measure the fiber height (height difference between where fibers are present and where fibers are not present) of the cellulose fibers in the observation sample. In this case, 100 cellulose fibers are extracted from a microscopic image in which the cellulose fibers can be seen, and the average fiber diameter is calculated from their fiber height. The average fiber length is calculated from the distance in the fiber direction. The average fiber diameter and average fiber length are number averages. The average aspect ratio is calculated by dividing the average fiber length by the average fiber diameter. The height analyzed in the AFM image can be considered the fiber diameter.

[0109] In Comparative Examples 3 and 4, it was difficult to confirm the presence of modified cellulose fibers using the AFM. Therefore, in Comparative Examples 3 and 4, the thickening composition obtained was diluted with IPA to 0.02 wt%, ultrasonically treated for 5 minutes, and one drop of the solution was dropped onto mica. After air drying, the sample was gold-sputtered using an MSP-1S (Vacuum Devices Co., Ltd.) and observed using a VE-8800 electron microscope (Keyence Corporation) with an accelerating voltage of 5 kV and a spot diameter of 8 mm.

[0110] [Average fiber diameter and average fiber length of raw cellulose fibers] Deionized water is added to the cellulose fibers to be measured to prepare a dispersion containing 0.01% by mass of cellulose. The dispersion is measured using a wet dispersion image analysis particle size distribution analyzer (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 volume: 1 mL, and sampling: 15%. At least 100 cellulose fibers 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.

[0111] [Anionic Group Content of Anion-Modified Cellulose Fibers and Modified Cellulose Fibers] A dry mass of 0.5 g of the cellulose fiber to be measured is placed in a beaker and mixed with deionized water or a 2:1 (volume ratio) methanol / water mixture to a total volume of 55 mL. 5 mL of 0.01 M aqueous sodium chloride solution is then added to prepare a dispersion. The dispersion is stirred until the cellulose fiber to be measured is fully dispersed. 0.1 M hydrochloric acid is added to the dispersion to adjust the pH to 2.5-3. Using an automatic titrator (manufactured by DKK-TOA Corporation, product name "AUT-701"), 0.05 M aqueous sodium hydroxide solution is added dropwise to the dispersion with a waiting time of 60 seconds, and the conductivity and pH values ​​are measured every minute. Measurements are continued until the pH reaches approximately 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 using the following formula: Anionic group content (mmol / g) = [Titer of aqueous sodium hydroxide solution (mL) × Concentration of aqueous sodium hydroxide solution (0.05 M)] / [Mass of cellulose fiber to be measured (0.5 g)]

[0112] [Aldehyde group content of oxidized cellulose fiber] The carboxy group content of the oxidized cellulose fiber to be measured is measured by the above-mentioned method for measuring the anionic group content. Separately, 100 g of the aqueous dispersion of oxidized cellulose fiber to be measured (solids content: 1.0% by mass), 100 g of acetate buffer (pH 4.8), 0.33 g of 2-methyl-2-butene, and 0.45 g of sodium chlorite were added to a beaker and stirred at 25°C for 16 hours to oxidize any remaining aldehyde groups in the oxidized cellulose fiber. After the reaction was completed, the cellulose fiber was washed with deionized water to obtain cellulose fiber with the aldehyde groups oxidized. The carboxy group content of the dried product obtained after freeze-drying was measured using the above-mentioned method for measuring anionic group content, and the "carboxy group content of the oxidized oxidized cellulose fiber" was calculated. Next, the aldehyde group content of the oxidized cellulose fiber to be measured was calculated using Equation 1.

[0113] Aldehyde group content (mmol / g) = (carboxyl group content of oxidized cellulose fiber after oxidation treatment) - (carboxyl group content of oxidized cellulose fiber to be measured) Equation 1

[0114] [Solid content in dispersion] The measurement is performed using a halogen moisture meter (Shimadzu Corporation; product name "MOC-120H"), with 1 g of sample measured every 30 seconds at a constant temperature of 150°C, and the value when the mass loss is 0.1% or less of the initial amount of the sample is taken as the solid content.

[0115] [Amount of modified group bonded and introduction rate of modified cellulose fiber] The amount of modified group bonded is determined by the following IR measurement method, and the bonded amount and introduction rate are calculated using the following formula. Specifically, the IR measurement involves measuring the infrared absorption spectrum of dried modified cellulose fiber by the ATR method using an infrared absorption spectrometer (IR) (Nicolet 6700, manufactured by Thermo Fisher Scientific), and the bonded amount and introduction rate of the modified group are calculated using formulas A and B. The following describes the case where the anionic group is a carboxy group, i.e., the case of oxidized cellulose fiber. The following "1720 cm" -1 The "peak intensity" is the peak intensity derived from the carbonyl group. In the case of an anionic group other than a carboxy group, the value of the wave number may be appropriately changed to calculate the bond amount and introduction rate of the modifying group.

[0116] <Formula A-1 (Ionic bond)> Amount of modified group bound (mmol / g) = a × (bc) ÷ b a: Carboxylic group content of oxidized cellulose fiber (mmol / g) b: 1720 cm of oxidized cellulose fiber -1 Peak intensity of c: 1720 cm of modified cellulose fiber -1 Peak intensity of <Formula A-2 (in the case of an amide bond)> Amount of modified group bound (mmol / g) = de d: Carboxylic group content of oxidized cellulose fiber (mmol / g) e: Carboxylic group content of modified cellulose fiber (mmol / g) <Formula B> Modification group introduction rate (mol%) = 100 × f / g f: Amount of modified group bound (mmol / g) g: Carboxylic group content of oxidized cellulose fiber (mmol / g)

[0117] [Confirmation of crystalline structure in modified cellulose fibers] The crystalline structure of the modified cellulose fiber is confirmed by measurement under the following conditions using an X-ray diffractometer (MiniFlexII, manufactured by Rigaku Corporation). The measurement conditions were as follows: X-ray source: Cu / Kα-radiation, tube voltage: 30 kV, tube current: 15 mA, measurement range: diffraction angle 2θ = 5 to 45°, X-ray scan speed: 10° / min. The measurement sample was a cellulose fiber to be measured, with an area of ​​320 mm. 2 The cellulose is compressed into a pellet with a thickness of 1 mm. The degree of crystallinity of the cellulose type I crystal structure is calculated from the obtained X-ray diffraction intensity using the following formula C.

[0118] <Formula C> Cellulose type I crystallinity (%) = [(I 22.6 -I 18.5 ) / I 22.6 ]×100 [In the formula, I 22.6is the diffraction intensity of the lattice plane (002 plane) (diffraction angle 2θ = 22.6°) in X-ray diffraction, I 18.5 indicates the diffraction intensity of the amorphous part (diffraction angle 2θ = 18.5°).

[0119] On the other hand, if the crystallinity obtained by the above formula C is 35% or less, in order to improve calculation accuracy, it is preferable to calculate based on the following formula D, in accordance with the description on pages 199-200 of the "Wood Science Experiment Manual" (edited by the Japan Wood Research Society; published in April 2000). Therefore, when the crystallinity obtained by the above formula C is 35% or less, the value calculated based on the following formula D can be used as the crystallinity.

[0120] <Formula D> Cellulose type I crystallinity (%) = [A c / (A c +A a )]×100 [In the formula, A c is the sum of the peak areas of the lattice planes (002 plane) (diffraction angle 2θ = 22.6°), (011 plane) (diffraction angle 2θ = 15.1°), and (0-11 plane) (diffraction angle 2θ = 16.2°) in X-ray diffraction, A a indicates the peak area of ​​the amorphous portion (diffraction angle 2θ = 18.5°), and each peak area is determined by fitting the obtained X-ray diffraction chart with a Gaussian function.

[0121] [Cellulose fiber (equivalent amount) in modified cellulose fiber] The cellulose amount (equivalent amount) in a modified cellulose fiber is the amount of cellulose in the modified cellulose fiber excluding the modifying group. In the modified cellulose fiber of the present invention, the formula weight of the modifying group may be considerably larger (for example, than the molecular weight of glucose). Therefore, in this specification, when it is appropriate to explain the difference in formula weight of the modifying group without considering the difference, the amount of cellulose constituting the modified cellulose fiber (equivalent amount) is expressed rather than the amount of modified cellulose fiber. The cellulose fiber (equivalent amount) in the modified cellulose fiber is measured by the following method.

[0122] (1) When one type of "modifying compound" is added The amount of cellulose fiber (equivalent amount) is calculated by the following formula E. <Formula E> Amount of cellulose fiber (equivalent amount) (g) = mass of modified cellulose fiber (g) / [1 + molecular weight of modifying compound (g / mol) × bonding amount of modifying group (mmol / g) × 0.001] (2) When two or more types of "modifying compounds" are added The amount of cellulose fiber (equivalent amount) is calculated taking into consideration the molar ratio of each compound (that is, the molar ratio when the total molar amount of the compounds added is taken as 1).

[0123] Production Example 1 (Production of anion-modified fine cellulose fibers) 10 g of bleached coniferous kraft pulp (trade name: Hinton, manufactured by West Fraser) as natural cellulose was thoroughly stirred in 990 g of ion-exchanged water, and then 0.13 g of 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO, manufactured by Aldrich, 98% by mass), 1.3 g of sodium bromide, and 27 g of a 10.5% by mass aqueous solution of sodium hypochlorite (10.5% by mass aqueous solution) were added to the 10 g of pulp in this order.

[0124] During this process, pH stat titration was performed using an automatic titrator (DKK-TOA Corporation, AUT-701), and 0.5 M aqueous sodium hydroxide solution was added dropwise to maintain the pH at 10.5. The reaction was carried out for 120 minutes (20°C) at a stirring speed of 200 rpm, after which the mixture was thoroughly washed with ion-exchanged water and then dehydrated to obtain anion-modified cellulose fibers with a solids content of 27.2%. The anionic groups in the resulting anion-modified cellulose fibers were carboxy groups, and the carboxy group content was 1.3 mmol / g.

[0125] Production Example 2 (Production of adhesive composition containing modified cellulose fiber) 2.0 g of the anion-modified cellulose fiber obtained in Production Example 1 (absolute dry mass) and 193 g of ion-exchanged water were mixed and stirred with a mechanical stirrer at room temperature (25°C) for 30 minutes. Subsequently, 4.5 g of 1 M aqueous hydrochloric acid solution was added to the mixture, and the mixture was stirred at room temperature for 1 hour to allow the reaction to proceed. After the reaction was completed, the filtrate was thoroughly washed with ion-exchanged water until the conductivity measured with a compact electrical conductivity meter (HORIBA, Ltd., LAQUAtwin EC-33B) was 200 μs / cm or less, and the hydrochloric acid and generated salt were removed. Subsequently, the solvent was replaced with 1-methoxy-2-propanol (PGME), and an anion-modified fine cellulose fiber dispersion (solids concentration 2.0%) in which carboxyl group-containing fine cellulose fibers were swollen in PGME was obtained.

[0126] 21.4 g of the resulting dispersion was mixed with 0.27 g of monoamine (Jeffamine M-2070, manufactured by Huntsman, USA, PO / EO (molar ratio) = 10 / 31) and stirred at 25°C for 1 hour to obtain a dispersion of modified cellulose fibers. 20 g of epoxy resin A (bisphenol A-type epoxy resin, jER828, manufactured by Mitsubishi Chemical Corporation, viscosity 120-150 P / 25°C, epoxy equivalent 184-194) was then added and stirred at 25°C for an additional 1 hour. The resulting mixture was dispersed five times at 150 MPa using a high-pressure homogenizer (NanoVata L-ES, manufactured by Yoshida Kikai Kogyo Co., Ltd.).

[0127] The solvent was removed from the resulting dispersion to obtain a resin composition containing the modified cellulose fiber and the epoxy resin. The resulting modified cellulose fibers had a bonding amount of modifying groups (groups in which an (EO / PO) chain position is bonded to an alkyl group) of 0.30 mmol / g, a modification group introduction rate of 23.4 mol%, a cellulose type I crystallinity of 60%, an average fiber diameter of 2.7 nm, an average fiber length of 594 nm, and an average aspect ratio of 220. The above physical properties of the modified cellulose were determined by measuring the physical properties of modified cellulose obtained by carrying out the same dispersion process except for the addition of resin. The same applies below. Here, the monoamine is a monoamine having an alkylene oxide chain, i.e., an (EO / PO) chain.

[0128] Production Example 3 (Production of a resin composition containing shortened modified cellulose fibers) 2.0 g (bone-dry mass) of the anion-modified cellulose fiber obtained in Production Example 1 and 193 g of ion-exchanged water were mixed and stirred with a mechanical stirrer at room temperature (25°C) for 30 minutes. Subsequently, 24.5 g of 1 M aqueous hydrochloric acid was added to the mixture, and the mixture was stirred at room temperature for 1 hour to allow the reaction to proceed. After the reaction was completed, the filtrate was thoroughly washed with ion-exchanged water until the electrical conductivity measured with a compact electrical conductivity meter (HORIBA, Ltd., LAQUAtwin EC-33B) was 200 μs / cm or less, and the hydrochloric acid and generated salt were removed. Then, 1.8 g (bone-dry mass) of the obtained anion-modified cellulose fiber was placed in a vial equipped with a magnetic stirrer and a stirrer, and ion-exchanged water was added until the mass of the treatment solution reached 36 g. The treatment solution was reacted at 95°C for 12 hours to obtain an aqueous suspension of shortened anion-modified cellulose fiber.

[0129] The solvent was then replaced with PGME to obtain a dispersion of shortened, anion-modified cellulose fibers (solids concentration 2.0%) in which carboxyl group-containing cellulose fibers were swollen in PGME. 21.4 g of the resulting dispersion was mixed with 0.27 g of monoamine (Jeffamine M-2070, manufactured by Huntsman, USA, PO / EO (molar ratio) = 10 / 31) and stirred at 25°C for 1 hour to obtain a dispersion of shortened, modified cellulose fibers. 20 g of epoxy resin A was then added and stirred for an additional 1 hour at 25°C. The resulting mixture was dispersed five times at 150 MPa using a high-pressure homogenizer (NanoVita L-ES, manufactured by Yoshida Kikai Kogyo Co., Ltd.).

[0130] The solvent was removed from the resulting dispersion to obtain a resin composition containing shortened modified cellulose fibers and epoxy resin. The resulting modified cellulose fibers had a modified group content of 0.30 mmol / g (an alkyl group bonded to an (EO / PO) chain position), a modification group introduction rate of 23.4 mol%, a cellulose type I crystallinity of 65%, an average fiber length of 132 nm, an average fiber diameter of 3.3 nm, and an average aspect ratio of 40.

[0131] Production Example 4 (Production of long-fiber anion-modified fine cellulose fibers) Eight grams of bleached coniferous kraft pulp (manufactured by West Fraser, product name: Hinton) as natural cellulose was thoroughly stirred with 760 g of ion-exchanged water, and then 0.09 g of TEMPO (manufactured by Aldrich, free radical, 98% by mass), 1.0 g of sodium bromide, and 21 g of a 5.0% by mass aqueous solution of sodium hypochlorite (3.8 mmol / g per gram of pulp) were added to the 8 g of pulp in this order.

[0132] During this process, a 0.5 M aqueous solution of sodium hydroxide was added dropwise using a pH-stat titration system with an automatic titrator (DKK-TOA Corporation, AUT-701) 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, yielding a suspension of anion-modified cellulose fibers in which the anionic group was a carboxy group (i.e., oxidized cellulose fibers).

[0133] The resulting suspension of anion-modified cellulose fibers was adjusted to pH 2 with 0.01 M hydrochloric acid, and the anion-modified cellulose fibers were thoroughly washed with ion-exchanged water until the conductivity of the filtrate measured with a compact electrical conductivity meter (HORIBA, Ltd., LAQUAtwin EC-33B) was 200 μs / cm or less. The anion-modified cellulose fibers were then dehydrated to obtain cake-like anion-modified cellulose fibers. The carboxyl group content of the resulting anion-modified cellulose fibers was 1.3 mmol / g.

[0134] Ion-exchanged water was added to the resulting anion-modified cellulose fiber to a solids concentration of 0.5% and stirred at 25°C for 1 hour. 0.27 g of monoamine (Jeffamine M-2070, manufactured by Huntsman, USA, PO / EO (molar ratio) = 10 / 31) was added to 80 g of the resulting dispersion and stirred at 25°C for 1 hour to obtain a dispersion of modified cellulose fiber. The resulting mixture was dispersed once at 100 MPa using a high-pressure homogenizer (NanoVita L-ES, manufactured by Yoshida Kikai Kogyo Co., Ltd.). PGME was then added to a solids concentration of 0.17% and stirred at 25°C for an additional 1 hour. The resulting mixture was dispersed once at 100 MPa using a high-pressure homogenizer.

[0135] The resulting dispersion was mixed with PGME while removing the ion-exchanged water to obtain a PGME dispersion of modified cellulose fibers. 20 g of epoxy resin A was then added to the resulting dispersion and stirred at 25°C for 1 hour. The resulting mixture was dispersed once using a high-pressure homogenizer at 50 MPa. The solvent was removed from the resulting dispersion to obtain a resin composition containing epoxy resin. The resulting modified cellulose fibers had a bonding amount of modifying groups (groups in which an (EO / PO) chain position is bonded to an alkyl group) of 0.30 mmol / g, a modification group introduction rate of 23.4 mol%, a cellulose type I crystallinity of 43%, an average fiber length of 4870 nm, an average fiber diameter of 111 nm, and an average aspect ratio of 44.

[0136] Examples 1 and 2 (Production of adhesive composition) To 10 g of the resin composition obtained in Production Example 3, 0.5 g of dicyandiamide (a polyaddition curing agent) and 0.3 g of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (a curing accelerator, DCMU99 manufactured by Hodogaya Chemical Co., Ltd.) were added, and the mixture was stirred for 2 minutes and degassed for 2 minutes using an automatic revolving mixer (Thinky Corporation, Awatori Rentaro) at room temperature (25°C), to obtain an adhesive composition containing modified cellulose fiber and an epoxy resin.

[0137] Examples 3 and 4 (However, Examples 3 and 4 are reference examples.) An adhesive composition was obtained in the same manner as in Examples 1 and 2, except that in Examples 1 and 2, 10 g of the resin composition obtained in Production Example 2 was used instead of 10 g of the resin composition obtained in Production Example 3.

[0138] Examples 5 and 6 An adhesive composition was obtained in the same manner as in Examples 1 and 2, except that in Examples 1 and 2, modified cellulose fibers using amino-modified silicone (manufactured by Dow Corning Toray Silicone Co., Ltd., SS-3551) as the modifying group were used instead of 10 g of the resin composition obtained in Production Example 3.

[0139] Examples 7 and 8 (However, Examples 7 and 8 are reference examples.) In Examples 3 and 4, adhesive compositions were obtained in the same manner as in Examples 3 and 4, except that 10 g of the resin composition obtained in Production Example 2 was a mixture of epoxy resin A and acrylic resin (NeoCryl A-1127) in proportions of 95% by mass and 5% by mass, respectively.

[0140] Comparative Examples 1 and 2 An adhesive composition was obtained in the same manner as in Examples 1 and 2, except that in Examples 1 and 2, 10 g of epoxy resin A not containing modified cellulose fiber was used instead of 10 g of the resin composition obtained in Production Example 3.

[0141] Comparative Examples 3 and 4 An adhesive composition was obtained in the same manner as in Examples 1 and 2, except that in Examples 1 and 2, 10 g of the resin composition obtained in Production Example 4 was used instead of 10 g of the resin composition obtained in Production Example 3.

[0142] [Evaluation of physical properties] The properties of the resulting adhesive composition were evaluated by the methods of the following Test Examples 1 and 2. The results are shown in Tables 1 to 3.

[0143] Test example 1 (shear adhesive strength test: similar adhesive) According to the shear strength test method specified in JASO M353, the adhesive composition was applied to two cold-rolled SPCC-SD steel sheets (100 mm x 25 mm x 1.6 mm) with a thickness of 0.15 mm, with an overlap of 12.5 mm. After removing any excess adhesive composition, the sheet was heated and cured at 130°C for two hours to prepare shear test specimens. The resulting test specimens were tested using a bench-top precision universal testing machine (Shimadzu Corporation, AGS-X) with a chuck distance of 111.5 cm at room temperature (25°C) and a tensile speed of 5 mm / min.

[0144] The cold-rolled steel sheet SPCC-SD used here was surface-treated before use in accordance with the surface treatment method for test piece materials described in JASO M353. The steel sheet was degreased with acetone, dried, immersed in rust-preventive oil (WD-40), and then left for 24 hours to allow the oil to drain. The numerical values ​​of the shear adhesive strength for the adhesive compositions obtained in Examples 1, 3, 5, and 7 and Comparative Example 3 were expressed as an index, with the value for the adhesive composition obtained in Comparative Example 1 being set at 100.

[0145] Test Example 2 (shear adhesive strength test: dissimilar adhesive) The test was carried out in the same manner as in Test Example 1, except that one cold-rolled steel plate SPCC-SD and one aluminum alloy plate A5052P were used instead of the two cold-rolled steel plates SPCC-SD in Test Example 1. The numerical values ​​of the shear adhesive strength for the adhesive compositions obtained in Examples 2, 4, 6 and 8 were expressed as an index, with the value for the adhesive composition obtained in Comparative Example 2 being set at 100.

[0146] Test Example 3 (evaluation of ejection properties) The dischargeability of adhesive compositions can be qualitatively evaluated through discharge tests using actual equipment. Here, 0.5 g of the sample was filled into a 2 mL syringe and manually squeezed out at room temperature to determine whether the viscosity was within the range that allowed discharge. Evaluation criteria A: Possible to discharge B: Difficult to dispense (somewhat possible to dispense with one hand) C: Difficult to excrete (somewhat possible to excrete using both hands) D: Unable to discharge

[0147] [Table 1]

[0148] [Table 2]

[0149] [Table 3]

[0150] Tables 1 to 3 show that the adhesive compositions of the present invention containing modified cellulose fibers with an average fiber length of 1000 nm or less, such as those in Examples 1 to 8, have improved shear adhesive strength compared to the comparative examples and are suitable as structural adhesives. Comparing Examples 1 and 3 and Examples 2 and 4, it can be seen that Examples 1 and 2, which use modified cellulose fibers with a short average fiber length and a small average aspect ratio, have excellent adhesive strength and dischargeability. A comparison between Example 1 and Comparative Example 1 (adhesion strength is 1.3 times) and a comparison between Example 2 and Comparative Example 2 (adhesion strength is 7.2 times) shows that the adhesive composition of the present invention has excellent adhesion between materials with different physical properties (for example, different materials containing metals with large linear expansion coefficients). [Industrial Applicability]

[0151] The adhesive composition of the present invention can be used for structural bonding of vehicle assemblies and the like.

Claims

1. A modified cellulose fiber having a cellulose I type crystal structure, an average fiber length of less than 150 nm, and an average fiber diameter of 1 nm or more and 300 nm or less; resin An adhesive composition (excluding aqueous adhesive compositions) containing the above.

2. 10. The composition of claim 1, wherein the modified cellulose fiber has an average aspect ratio of 200 or less.

3. 3. The composition of claim 1 or 2, wherein the modified cellulose fibers have an average aspect ratio of 100 or less.

4. The modified cellulose fiber is a cellulose fiber to which a modifying group is bonded, the modifying group contains at least one selected from the group consisting of (a) a hydrocarbon group, (b) a silicone chain, and (c) an alkylene oxide chain; The composition according to any one of claims 1 to 3.

5. The composition of claim 4, wherein the cellulose fibers are anionically modified cellulose fibers.

6. The composition according to claim 5, wherein the modifying group is bonded to the anionic group of the anionically modified cellulose fiber via an ionic and / or covalent bond.

7. The composition according to any one of claims 1 to 6, wherein the resin is a curable resin.

8. The composition of any one of claims 1 to 7, which is a structural adhesive composition.

9. The composition of any one of claims 1 to 8 used to bond vehicle assemblies.

10. The composition according to any one of claims 1 to 9, which is used to bond metal components.

11. The composition of claim 10 wherein the bonding surface of the metal component comprises aluminum.

12. The composition according to claim 10 or 11, which is used for bonding dissimilar metals.

13. A composition described in claim 10 or 11, used for bonding dissimilar metals having different linear expansion coefficients.

14. A modified cellulose fiber having a cellulose I type crystal structure, an average fiber length of less than 150 nm, and an average fiber diameter of 1 nm or more and 300 nm or less; resin A bonding method for bonding structures with an adhesive composition containing the above (however, this does not include a bonding method in which the adhesive composition is a water-based adhesive composition).

15. The bonding method according to claim 14, wherein the bonding surface of the structure comprises at least one material selected from the group consisting of metal, plastic, ceramic, and glass.

16. A modified cellulose fiber having a cellulose I type crystal structure, an average fiber length of less than 150 nm, and an average fiber diameter of 1 nm or more and 300 nm or less; resin A bonding method for bonding metal members with an adhesive composition containing the above (however, this does not include a bonding method in which the adhesive composition is a water-based adhesive composition).

17. 17. The bonding method of claim 16, wherein the bonding surface of the metal member comprises aluminum.

18. The bonding method according to any one of claims 14 to 17, which is used for bonding dissimilar metals.

19. A bonding method described in any one of claims 14 to 17, used for bonding dissimilar metals with different linear expansion coefficients.

20. The bonding method according to any one of claims 14 to 19, wherein the adhesive composition is discharged from a dispenser and applied to the structure.

21. The bonding method according to any one of claims 14 to 20, wherein the average aspect ratio of the modified cellulose fiber is 200 or less.

22. The bonding method according to any one of claims 14 to 21, wherein the average aspect ratio of the modified cellulose fiber is 100 or less.

Images