Composition containing rubber particles

Abstract

To provide a composition that exhibits superior elongation at break and elastic moduli when forming a resin film.SOLUTION: A composition is provided that contains modified cellulose fibers, rubber particles and resin. There are also provided a bonding method using the composition, a molding containing the composition, and a fiber composite material containing the composition.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a composition containing rubber particles.

Background Art

[0002] In recent years, adhesives have been used in various fields. For example, it is known that blades of wind turbines for wind power generation are made by bonding various members with an adhesive. Adhesives used for blades of wind turbines are required to have a certain elastic modulus and not break in order to withstand strong winds and long-term use.

[0003] For example, Patent Document 1 discloses an adhesive composition containing an adhesive resin and core-shell polymer particles, and it is described that such a composition has excellent fatigue resistance characteristics and undergoes cohesive failure during fatigue fracture.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Since the adhesive composition in Patent Document 1 contains core-shell polymer particles which are a kind of rubber particles, an effect of improving the elongation at break can be expected, but on the other hand, there is a problem that the elastic modulus decreases.

[0006] Therefore, the present invention relates to providing a composition excellent in elongation at break and elastic modulus when forming a resin film.

Means for Solving the Problems

[0007] The present invention relates to the following [1] to [5]. [1] A composition containing modified cellulose fibers, rubber particles, and resin. [2] The composition described in [1] above, which is an adhesive composition. [3] A bonding method using the composition described in [1] above. [4] A molded article containing the composition described in [1] above. [5] A fiber composite material containing the composition described in [1] above. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a composition that exhibits excellent elongation at break and elastic modulus when a resin film is formed. [Modes for carrying out the invention]

[0009] 1. Composition of the present invention The composition of the present invention contains modified cellulose fibers, rubber particles, and resin. Although the detailed mechanism by which the composition of the present invention exhibits such effects is unknown, it is presumed that a synergistic effect is produced by the combined action of the modified cellulose fibers contained in the formed resin film with the rubber particles contained in the resin film.

[0010] The composition of the present invention can be used as an adhesive or molded article by itself, or it can be used as an adhesive material for obtaining an adhesive by further blending it with other components.

[0011] [Modified cellulose fiber] The modified cellulose fiber in this invention is a cellulose fiber having a modifying group. Preferably, the modifying group is bonded to some or all of the hydroxyl groups of the cellulose fiber, or to a carboxyl group obtained by converting a hydroxyl group of a glucose unit to a carboxyl group, and more preferably, to a carboxyl group obtained by converting the C6 group (-CH2OH) of a glucose unit to a carboxyl group.

[0012] (Anionic modified cellulose fiber) Anionically modified cellulose fibers are cellulose fibers having one or more anionic groups, selected from the group consisting of carboxyl groups, ()phosphorous groups, and sulfonic acid groups, within their molecule. The introduction of anionic groups into cellulose fibers can be achieved by the methods described below. From the viewpoint of availability and effectiveness, anionically modified cellulose fibers having a carboxyl group as the anionic group (referred to as "oxidized cellulose fibers") are preferred, and anionically modified cellulose fibers in which the group at the C6 position (-CH2OH) of the glucose unit constituting the cellulose fiber is selectively converted to a carboxyl group (referred to as "TEMPO-oxidized cellulose fibers") are more preferred. The ion paired with the anionic group (counterion) is preferably a proton.

[0013] The anionic group content in anionically modified cellulose fibers 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 handling, it is preferably 3 mmol / g or less, more preferably 2.5 mmol / g or less, even more preferably 2 mmol / g or less, even more preferably 1.9 mmol / g or less, even more preferably 1.8 mmol / g or less, even more preferably 1.7 mmol / g or less, and even more preferably 1.5 mmol / g or less. Note that "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.

[0014] The bonding of a modifying group to an anionic group in an anionic-modified cellulose fiber means that the modifying group is bonded to an anionic group, preferably a carboxyl group, that the anionic-modified cellulose fiber possesses. The bonding modes between the modifying group and the anionic group include ionic bonds and / or covalent bonds. Examples of covalent bonds include amide bonds, ester bonds, and urethane bonds, with amide bonds being preferred.

[0015] (Modifying group) Examples of the modifying group include (a) a hydrocarbon group and (b) a polymer group. These modifying groups may be combined singly or in combination of two or more and bonded to the anionic modified cellulose fiber.

[0016] (a) Hydrocarbon group Examples of the hydrocarbon group include a monovalent hydrocarbon group, such as a linear or branched chain saturated hydrocarbon group, a linear or branched chain unsaturated hydrocarbon group, a cyclic saturated hydrocarbon group, an aryl group, an aralkyl group, and a heterocyclic aromatic hydrocarbon group. From the viewpoint of enhancing the adhesive strength, the number of carbon atoms of the hydrocarbon group is 1 or more, preferably 3 or more, more preferably 8 or more, still more preferably 10 or more. From the same viewpoint, it is preferably 30 or less, more preferably 22 or less, still more preferably 18 or less. The hydrocarbon group may have a substituent described later, and a part of the hydrocarbon group may be substituted with a hydrogen nitride group.

[0017] From the viewpoint of enhancing the adhesive strength, the linear or branched chain saturated hydrocarbon group is preferably a linear chain saturated hydrocarbon group. Examples of the chain saturated hydrocarbon group 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, an octacosanyl group, etc.

[0018] Examples of the chain unsaturated hydrocarbon group 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, an octadecenyl group.

[0019] Examples of cyclic saturated hydrocarbon groups include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, cyclododecyl, cyclotridecyl, cyclotetradecyl, and cyclooctadecyl groups.

[0020] Examples of aryl groups include phenyl, naphthyl, anthryl, phenanthryl, biphenyl, triphenyl, terphenyl groups, and groups in which these groups are substituted with substituents described later.

[0021] Examples of aralkyl groups include benzyl, phenethyl, phenylpropyl, phenylpentyl, phenylhexyl, phenylheptyl, phenyloctyl, and groups in which these groups are substituted with substituents described later. Examples of heterocyclic aromatic hydrocarbon groups include imidazole groups, methylimidazole groups, ethylimidazole groups, propylimidazole groups, 2-phenylimidazole groups, benzimidazole groups, and groups in which these groups are substituted with substituents.

[0022] (b) Polymer group In this invention, a polymer group is a functional group containing a polymer structure. From the viewpoint of increasing the adhesive strength of the composition, the formula weight (molecular weight) of the polymer group is preferably 100 or more, more preferably 200 or more, even more preferably 300 or more, even more preferably 500 or more, even more preferably 1,000 or more, and even more preferably 1,500 or more. From a similar viewpoint, it is preferably 1,000,000 or less, more preferably 100,000 or less, even more preferably 10,000 or less, even more preferably 7,000 or less, even more preferably 5,000 or less, even more preferably 4,000 or less, even more preferably 3,500 or less, and even more preferably 2,500 or less.

[0023] From the viewpoint of increasing the adhesive strength of the composition, the polymer group is preferably a functional group having a repeating structure linked by an oxygen atom, more preferably a functional group having a repeating structure linked by an oxygen atom, such as a polyoxyalkylene structure or a polysiloxane structure, more preferably having a polyoxyalkylene structure, and even more preferably an alkoxypolyoxyalkylene group.

[0024] From the viewpoint of increasing the adhesive strength of the composition, the polyoxyalkylene structure is preferably a (co)polymer structure of one or more oxyalkylenes selected from oxyalkylenes having 2 to 8 carbon atoms, more preferably a (co)polymer structure of one or more oxyalkylenes selected from oxyalkylenes having 2 to 4 carbon atoms, even more preferably a (co)polymer structure of one or two oxyalkylenes selected from ethylene oxide (EO) and propylene oxide (PO), and even more preferably a copolymer structure (EO / PO copolymer structure) in which ethylene oxide and propylene oxide are polymerized randomly or in blocks.

[0025] An example of a copolymer structure in which ethylene oxide and propylene oxide are polymerized randomly or in a blocky manner is the following formula:

[0026] [ka]

[0027] (In the formula, R 1 represents a hydrogen atom, a hydrocarbon group having 1 to 6 carbon atoms, or a -CH2CH(CH3)NH2 group. EO and PO are present randomly or in a blocky arrangement, where a is a positive number representing the average number of moles of EO added, and b is a positive number representing the average number of moles of PO added. Examples of structures include those shown in ).

[0028] R 1 From the viewpoint of increasing the adhesive strength of the composition, it is preferably a linear or branched alkyl group having 1 to 6 carbon atoms, and more preferably a methyl group.

[0029] From the viewpoint of increasing the adhesive strength of the composition, a is preferably 1 or more, more preferably 3 or more, even more preferably 6 or more, even more preferably 11 or more, even more preferably 15 or more, even more preferably 20 or more, even more preferably 25 or more, and even more preferably 30 or more. From a similar viewpoint, it is preferably 100 or less, more preferably 70 or less, even more preferably 60 or less, even more preferably 50 or less, and even more preferably 40 or less.

[0030] From the viewpoint of enhancing the adhesion of the composition, b is preferably 1 or more, more preferably 3 or more, and even more preferably 5 or more. From a similar viewpoint, it is preferably 50 or less, more preferably 40 or less, even more preferably 30 or less, even more preferably 25 or less, even more preferably 20 or less, even more preferably 15 or less, and even more preferably 10 or less. In the above formula, a+b represents the average number of moles added in total of EO and PO, and from the viewpoint of improving the adhesion of the composition, it is preferably 4 or more, more preferably 6 or more, and even more preferably 8 or more, and from the same viewpoint, it is preferably 100 or less, and more preferably 70 or less.

[0031] The PO content (mol%) in the EO / PO copolymer structure can be calculated based on a and b above, specifically from b × 100 / (a ​​+ b). From the viewpoint of improving the adhesion of the composition, the PO content is preferably 1 mol% or more, more preferably 5 mol% or more, even more preferably 7 mol% or more, even more preferably 10 mol% or more, and even more preferably 20 mol% or more. From a similar viewpoint, it is preferably 100 mol% or less, more preferably 90 mol% or less, even more preferably 85 mol% or less, even more preferably 75 mol% or less, even more preferably 60 mol% or less, even more preferably 50 mol% or less, even more preferably 40 mol% or less, and even more preferably 30 mol% or less.

[0032] (c) Further substituents The modifying group may have further substituents. Examples of substituents 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, sec-butoxycarbonyl, and tert-butoxycarbonyl groups. Examples include alkoxy-carbonyl groups with 1 to 6 carbon atoms, such as t-butoxycarbonyl, pentyloxycarbonyl, and isopentyloxycarbonyl groups; halogen atoms such as fluorine, chlorine, bromine, and iodine atoms; acyl groups with 1 to 6 carbon atoms, such as acetyl and propionyl groups; aralkyl groups; aralkyloxy groups; alkylamino groups with 1 to 6 carbon atoms; dialkylamino groups with 1 to 6 carbon atoms in the alkyl group; and hydroxyl groups.

[0033] [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 by attaching modifying groups to the anionic groups of the anionically modified cellulose fibers (step 2).

[0034] (Process 1) Raw material: cellulose fiber As cellulose fibers used as raw materials for anion-modified cellulose fibers, natural cellulose is preferred from an environmental standpoint. Examples include wood pulp such as coniferous pulp and hardwood pulp; cotton pulp such as cotton linters and cotton lint; non-wood pulp such as straw pulp and bagasse pulp; and bacterial cellulose. One of these can be used alone or in combination of two or more.

[0035] The average fiber diameter of the raw cellulose fibers is not particularly limited, but from the viewpoint of handling and cost, it is preferably 5 μm or more, more preferably 7 μm or more, and from the same viewpoint, preferably 500 μm or less, more preferably 300 μm or less. The average fiber diameter of the raw cellulose fibers can be determined by the method described in the examples below.

[0036] Furthermore, while the average fiber length of the raw cellulose fibers is not particularly limited, from the viewpoint of availability and cost, it is preferably 5 μm or more, more preferably 25 μm or more, and from the same viewpoint, 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.

[0037] Method for introducing anionic groups Methods for introducing a carboxyl group as an anionic group into cellulose fibers include, for example, oxidizing the hydroxyl group of the cellulose fiber to convert it into a carboxyl group, or reacting the hydroxyl group of the cellulose fiber with at least one selected from the group consisting of compounds having a carboxyl group, acid anhydrides of compounds having a carboxyl group, and derivatives thereof.

[0038] One method for oxidizing the hydroxyl groups of cellulose fibers is described in Japanese Patent Publication No. 2015-143336 or Japanese Patent Publication No. 2015-143337, which involves reacting 2,2,6,6-tetramethyl-1-piperidine-N-oxyl (TEMPO) as a catalyst with an oxidizing agent such as sodium hypochlorite and a bromide such as sodium bromide, using cellulose fibers as a raw material. By oxidizing cellulose fibers using TEMPO as a catalyst, the C6 group of glucose in the cellulose fiber constituent units is selectively converted to a carboxyl group, thereby obtaining the aforementioned oxidized cellulose fibers.

[0039] Methods for introducing sulfonic acid groups as anionic groups into cellulose fibers include adding sulfuric acid to the cellulose fibers and heating them. Methods for introducing ()phosphorous groups as anionic groups into cellulose fibers include mixing powder or aqueous solution of ()phosphorous or ()phosphorous derivatives with dry or wet cellulose fibers, or adding aqueous solution of ()phosphorous or ()phosphorous derivatives to a dispersion of cellulose fibers. When these methods are employed, dehydration and heat treatment are generally performed after mixing or adding powder or aqueous solution of ()phosphorous or ()phosphorous derivatives.

[0040] (Process 2) The introduction of modifying groups to the anionic groups of anionic-modified cellulose fibers is achieved by reacting the anionic-modified cellulose fibers with a compound for introducing modifying groups to the anionic groups (referred to as the "modifying compound"). Methods for introducing the modifying groups include (1) introduction via ionic bonding, as described in Japanese Patent Publication No. 2015-143336, and (2) introduction via amide bonding, as described in Japanese Patent Publication No. 2015-143337. After the completion of step 2, post-treatment may be performed as appropriate to remove unreacted compounds, etc. Examples of post-treatment methods include filtration, centrifugation, and dialysis.

[0041] (Refining process) By refining the cellulose fibers at any stage of the modified cellulose fiber manufacturing method (for example, before step 1, before step 2, and after step 2), micrometer-scale cellulose fibers can be refined to a nanometer scale. Reducing the average fiber diameter to nanometer size is preferable because it improves dispersibility in the resin.

[0042] For the micronization process, known micronization methods can be employed. For example, to obtain modified cellulose fibers with an average fiber diameter of nanometer size, a processing method using a grinder such as a muscoloider or a processing method using a high-pressure homogenizer in a medium can be carried out.

[0043] Examples of media 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 can be used individually or in mixtures of two or more. The amount of media used should be an effective amount that can disperse the modified cellulose fibers, preferably 1 mass or more, more preferably 2 mass or more, preferably 500 mass or less, and more preferably 200 mass or less, relative to the modified cellulose fibers.

[0044] In addition to high-pressure homogenizers, other known dispersers can be suitably used in the micronization process. For example, dissociators, beaters, low-pressure homogenizers, grinders, mascolloiders, cutter mills, ball mills, jet mills, short-screw extruders, twin-screw extruders, ultrasonic stirrers, and household juicer mixers can be used. Furthermore, the solid content of the modified cellulose fibers in the micronization process is preferably 50% by mass or less.

[0045] (Short fiber treatment) In any step of the method for producing modified cellulose fibers, the cellulose fibers may be subjected to a short fiber treatment. The short fiber treatment can be carried out by subjecting the target cellulose fibers to one or more treatment methods selected from the group consisting of (i) alkali treatment, (ii) acid treatment, (iii) heat treatment, ultraviolet treatment, electron beam treatment, mechanical treatment, and enzymatic treatment.

[0046] [Properties of modified cellulose fibers] The main properties of the modified cellulose fibers in this invention are as follows:

[0047] (Crystal structure) From the viewpoint of increasing adhesive strength, modified cellulose fibers having a cellulose type I crystalline structure are preferred. From the viewpoint of increasing adhesive strength, the degree of crystallinity of the modified cellulose fibers is preferably 10% or more, more preferably 15% or more, and even more preferably 20% or more. 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 degree of crystallinity of cellulose fibers is the degree of 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 natural cellulose, and the degree of cellulose type I crystallinity means the proportion of the crystalline region in the total amount of cellulose fibers. The presence or absence of a cellulose type I crystalline structure can be determined by the presence of a peak at 2θ = 22.6° in X-ray diffraction measurement.

[0048] (Average fiber diameter) The modified cellulose fibers are preferably those that have been micronized to a 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 viewpoint of handling, availability, and cost, and preferably 300 nm or less, more preferably 200 nm or less, even more preferably 150 nm or less, and even more preferably 120 nm or less, from the viewpoint of improving handling, dispersibility, and adhesive strength.

[0049] (Average fiber length) From the viewpoint of increasing adhesive strength, the average fiber length of the modified cellulose fibers is preferably 10 nm or more, more preferably 30 nm or more, and even more preferably 50 nm or more. On the other hand, from the viewpoint of increasing extrusion properties and adhesive strength, it is preferably 1000 nm or less, more preferably 500 nm or less, and even more preferably 300 nm or less.

[0050] (Average aspect ratio) The average aspect ratio of the modified cellulose fibers 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 from the viewpoint of increasing extrusion and adhesive strength, it is preferably 300 or less, more preferably 200 or less, and even more preferably 100 or less. By keeping the average aspect ratio within the above range, excellent adhesion is achieved between materials with different physical properties (for example, materials with different coefficients of thermal expansion). The average fiber diameter, average fiber length, and average aspect ratio of the modified cellulose fibers are determined by the method described in the examples below.

[0051] (Amount of modifying group attached and rate of introduction) From the viewpoint of increasing adhesive strength, the amount of modifying groups bound to the modified cellulose fibers is preferably 0.01 mmol / g or more, and from the same viewpoint, preferably 3.0 mmol / g or less. When any two or more modifying groups are simultaneously introduced into the modified cellulose fibers, the amount of modifying groups bound is preferably within the above range.

[0052] From the viewpoint of dispersibility, the introduction rate of modifying groups in modified cellulose fibers is preferably 10 mol% or more, and the higher the rate, the better, preferably 100 mol%. When two or more arbitrary modifying groups are introduced simultaneously, it is preferable that the total introduction rate does not exceed the upper limit of 100 mol% while remaining within the above range.

[0053] The amount and rate of modification groups can be adjusted by the type and amount of modification compound added, the reaction temperature, the reaction time, the type of solvent, etc. The amount (mmol / g) and rate (mol%) of modification groups refer to the amount and percentage of modification groups introduced (bonded) to the anionic groups in the modified cellulose fibers. For example, when the anionic group is a carboxyl group, the amount and rate of modification groups in the modified cellulose fibers can be calculated using the method described in the examples below.

[0054] [Rubber particles] The rubber particles used in the present invention are preferably those that can be uniformly dispersed in the resin. Examples include diene-based rubber particles such as natural rubber particles, polybutadiene rubber particles, and butadiene nitrile rubber particles, as well as acrylic rubber particles and urethane rubber particles. Among these, core-shell rubber particles having a shell layer that enhances compatibility with the resin are preferred. Core-shell rubber particles are commercially available; for example, Kaneka's KaneAce is one such product.

[0055] The average particle size of the rubber particles is preferably 1 nm or more, more preferably 50 nm or more, and even more preferably 80 nm or more, from the viewpoint of improving the adhesive strength of the composition, while from the viewpoint of the elastic modulus of the composition and improving the adhesive strength of the composition, it is preferably 500 nm or less, more preferably 200 nm or less, and even more preferably 120 nm or less.

[0056] 〔resin〕 In the present invention, from the viewpoint of use in various structures, water-insoluble resins that do not dissolve in water or have extremely low solubility in water are preferred. Specifically, a water-insoluble resin is defined as a resin whose solubility in water at 25°C is 1 mg or less per 100 g of water.

[0057] The solubility of the above-mentioned substance is measured as follows: Add 100 mg of resin to 1 L (25°C) of water and stir for 24 hours using a stirring device such as a stirrer. Then, centrifuge the solution (or suspension) at 3000 × g at 25°C for 30 minutes and collect the insoluble residue. Dry this residue at 105°C for 3 days and measure the mass after drying (dry mass). Resins with a dry mass of less than 99 mg are classified as water-soluble, and resins with a dry mass of 99 mg or more are classified as water-insoluble.

[0058] The resins used in this invention are preferably resins that have adhesive properties on their own, or resins that exhibit adhesive properties when used in combination with a curing agent. The resins may be used alone or as a mixture of two or more resins. The resins used in this invention are used as the matrix of the composition according to the present invention and are different from the rubber particles.

[0059] Specific examples of resins include epoxy resins, urethane resins, acrylic resins, polyvinyl chloride resins, phenoxy resins, phenolic resins, urea resins, melamine resins, polyimide resins, unsaturated polyester resins, diallyl phthalate resins, and rubber-based resins.

[0060] Among resins, curable resins (e.g., epoxy resins, urethane resins, phenoxy resins, phenolic resins, urea resins, melamine resins) are preferred from the viewpoint of increasing adhesive strength. Depending on the type of resin, photocuring and / or heat curing treatments can be performed.

[0061] [Other ingredients] The composition of the present invention may optionally contain components known in the field of adhesives, such as polymerization initiators, plasticizers, stabilizers, lubricants, surfactants, and inorganic fillers. The amount of such components is not particularly limited, and appropriate amounts may be used as appropriate.

[0062] The mass ratio of rubber particles to resin, when calculated in terms of blending amount, is preferably 0.01 or higher, more preferably 0.03 or higher, and even more preferably 0.05 or higher, and from the same viewpoint, preferably 1 or lower, more preferably 0.2 or lower, and even more preferably 0.1 or lower.

[0063] The mass ratio of modified cellulose fibers to resin in the composition of the present invention, when calculated in terms of blending amount, on a cellulose basis (excluding modifying groups, etc.) (however, if the cellulose has anionic groups, on an anionically modified cellulose basis), is preferably 0.01 / 100 or more, more preferably 0.05 / 100 or more, even more preferably 0.1 / 100 or more, even more preferably 0.3 / 100 or more, and even more preferably 0.5 / 100 or more, from the viewpoint of the elastic modulus of the composition and improvement of adhesive strength by the composition. On the other hand, from the viewpoint of handling during manufacturing, it is preferably 30 / 100 or less, more preferably 20 / 100 or less, even more preferably 15 / 100 or less, even more preferably 10 / 100 or less, even more preferably 7 / 100 or less, even more preferably 5 / 100 or less, and even more preferably 3 / 100 or less.

[0064] The amount of modified cellulose fibers in the composition of the present invention, when calculated in terms of blending amount, is preferably 0.1% 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 (excluding modifying groups, etc.), from the viewpoint of improving the elastic modulus of the composition and the adhesive strength of the composition. On the other hand, from the viewpoint of handling during manufacturing, it is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 4% by mass or less.

[0065] The amount of rubber particles in the composition of the present invention, when calculated in terms of blending amount, is preferably 0.1% by mass or more, more preferably 1% by mass or more, and even more preferably 3% by mass or more, and from the same viewpoint, preferably 50% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less.

[0066] The amount of resin in the composition of the present invention, when calculated as the blending amount, is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more, and from the same viewpoint, preferably 95% by mass or less, more preferably 92% by mass or less, and even more preferably 90% by mass or less.

[0067] The composition of the present invention and the adhesive using the composition are liquid or solid (e.g., pellet or powder) at room temperature (25°C). In the case of a solid, it can be made into a paste, solution, or dispersion by adding an appropriate medium. It can also be heated to a liquid state as needed before use.

[0068] [Method for manufacturing the composition] The composition of the present invention can be produced, for example, by mixing the modified cellulose fibers, the rubber granules, and the resin. Furthermore, a solvent, a curing agent, and other components can be mixed in as needed. The method for mixing each component of the composition is not particularly limited and general methods include using a stirrer, ultrasonic homogenizer, high-pressure homogenizer, etc.

[0069] Examples of solvents that can be used during manufacturing include dimethylformamide, ethyl acetate, methyl methacrylate, ethanol, isopropanol, N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N,N-dimethylacetamide, tetrahydrofuran (THF), diester of succinic acid and triethylene glycol monomethyl ether, acetone, methyl ethyl ketone (MEK), acetonitrile, dichloromethane, chloroform, toluene, 1-methoxy-2-propanol (PGME), acetic acid, etc., and these can be used individually or in combination of two or more. When a solvent is used, the amount is preferably 50 parts by mass or more, more preferably 100 parts by mass or more, per 100 parts by mass of resin, while preferably 5000 parts by mass or less, and more preferably 2000 parts by mass or less.

[0070] 2. The bonding method of the present invention One example of the bonding method of the present invention is to apply the composition of the present invention onto a structure (or a component thereof) and then bond it to the other structure (or component thereof).

[0071] There are no particular limitations on the method of applying the composition, but examples include using a spray, a sealer gun, a dispenser, a nozzle, a brush, a spatula, etc.

[0072] After bonding one structure to the other, the bonding can be completed by maintaining a temperature of, for example, -30 to 200°C for 1 minute to 3 days.

[0073] 3. Molded article of the present invention Examples of molded articles of the present invention include molded articles obtained by molding the composition of the present invention, or a mixture of the composition of the present invention and another resin composition. Such molded articles can be produced by appropriately using known molding methods such as coating, extrusion, injection molding, press molding, casting, or solvent casting, using the composition of the present invention or a mixture containing the composition.

[0074] 4. Fiber composite material of the present invention Examples of fiber composite materials of the present invention include carbon fiber composite materials and glass fiber composite materials obtained by molding a mixture of the composition of the present invention and fibers such as carbon fibers or glass fibers.

[0075] The molding method for fiber composite materials is not particularly limited and can be carried out according to known methods. Examples of molding methods include pre-forming the molding material into a prepreg and heating it under pressure by pressing or autoclaving, as well as RTM (Resin Transfer Molding) molding, VaRTM (Vacuum Assist Resin Transfer Molding) molding, lamination molding, and hand lay-up molding.

[0076] The amount of fibers in the fiber composite material of the present invention is preferably 5% by mass or more, and more preferably 9% by mass or more. On the other hand, the amount of fibers is preferably 70% by mass or less, and more preferably 60% by mass or less.

[0077] The compositions, molded articles, and fiber composite materials of the present invention can be used as adhesives and structural components in automobiles, railway vehicles (bullet trains, electric trains), ships, aircraft (airplanes and drones), buildings, wind turbines, electronics, space industries, and the like. [Examples]

[0078] The present invention will be specifically described below with reference to examples. The following examples are merely illustrative of the present invention and do not imply any limitation. "Normal pressure" refers to 101.3 kPa, and "room temperature" refers to 25°C.

[0079] [Average fiber diameter and average fiber length of cellulose fibers, anionically modified cellulose, and modified cellulose fibers] Depending on the size of the cellulose fiber being measured, one of the following two measurement methods was selected for measurement. (1) Deionized water or N,N-dimethylformamide (DMF) was added to the cellulose fibers to be measured to prepare a dispersion with a content of 0.0001% by mass. The dispersion was dropped onto mica and dried to serve as the observation sample. An atomic force microscope (AFM) (Digital Instruments, Nanoscope II Tappingmode AFM; probe used: Nanosensors, Point Probe (NCH)) was used to measure the fiber height (difference in height between areas with and without fibers) of the cellulose fibers in the observation sample. At that time, 100 cellulose fibers were extracted from the microscope image in which the cellulose fibers could be confirmed, and the average fiber diameter was calculated from their fiber heights. The average fiber length was calculated from the distance in the direction of the fibers.

[0080] (2) Deionized water was added to the cellulose fibers to be measured to prepare a dispersion with a content of 0.01% by mass. This dispersion was measured using a wet dispersion type image analysis particle size distribution analyzer (Jusco International Co., Ltd., 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, sampling: 15%. The length of the short axis when the cellulose fiber is approximated as a rectangle was defined as the fiber diameter, and the length of the long axis was defined as the fiber length. These values ​​were measured for 100 cellulose fibers, and the average value was calculated.

[0081] [Anionic group content of anionic-modified cellulose] A 0.5 g dry weight of the cellulose fiber to be measured was placed in a beaker, and deionized water or a methanol / deionized water = 2 / 1 (volume ratio) mixed solvent was added to make a total volume of 55 mL. 5 mL of 0.01 M sodium chloride aqueous solution was then added to prepare a dispersion. The dispersion was stirred until the cellulose fiber was sufficiently dispersed. 0.1 M hydrochloric acid was added to the dispersion to adjust the pH to 2.5-3. Using an automatic titrator (Toa DKK Co., Ltd., AUT-701), 0.05 M sodium hydroxide aqueous solution was added dropwise to the dispersion with a waiting time of 60 seconds, and the conductivity and pH values ​​were measured every minute. Measurements were continued until the pH reached approximately 11, and a conductivity curve was obtained. From this conductivity curve, the amount of sodium hydroxide titration was determined, and the anionic group content of the cellulose fiber was calculated using the following formula. Anionic group content (mmol / g) = [Titration volume of sodium hydroxide aqueous solution (mL) × Concentration of sodium hydroxide aqueous solution (0.05M)] / [Mass of cellulose fiber to be measured (0.5g)]

[0082] [Content of each ingredient] The amounts of each component were calculated. The amount of modified cellulose was calculated assuming that all of the short-fiber anionic modified cellulose fibers and amines were ionically bonded. The glucose units in the modified cellulose were calculated from the amount of modified cellulose and the amount of modified cellulose added.

[0083] [Confirmation of crystal structure in various cellulose fibers] The crystal structures of various cellulose fibers, including cellulose fibers, anionically modified cellulose fibers, and modified cellulose fibers, were confirmed by measuring them using a diffractometer (MiniFlexII, Rigaku Corporation) under the following conditions. Measurement pellet preparation conditions: Pressure is applied to the target cellulose fibers in the range of 10-20 MPa using a tablet molding machine, with an area of ​​320 mm². 2 ×Smooth pellets with a thickness of 1 mm were prepared. X-ray diffraction analysis conditions: Step angle 0.01°, scan speed 10° / min, measurement range: diffraction angle 2θ = 5~40° X-ray source: Cu / Kα-radiation, tube voltage: 15kv, tube current: 30mA Peak splitting conditions: After removing background noise, a Gaussian function was fitted so that the error between 2θ = 13-23° was within 5%.

[0084] The degree of crystallinity of the cellulose type I crystal structure was calculated using the area of ​​the X-ray diffraction peaks obtained by the aforementioned peak splitting, based on the following equation (A). Cellulose type I crystallinity (%) = [I cr / ( I cr +I am )] × 100 (A) [In the formula, I cr This is the area of ​​the diffraction peak at the lattice plane (002 plane) (diffraction angle 2θ = 22-23°) in X-ray diffraction, I am This indicates the area of ​​the diffraction peak in the amorphous region (diffraction angle 2θ = 18.5°).

[0085] [Anionic modified cellulose fiber] Anionically modified cellulose fibers having the physical properties listed in Table 1 were used as raw materials.

[0086] [Table 1]

[0087] Such anionically modified cellulose fibers can be prepared, for example, by the TEMPO oxidation treatment described below.

[0088] [TEMPO oxidation treatment] In a 2L PP beaker equipped with a mechanical stirrer and stirring blades, weigh out 10g of bleached kraft pulp fiber from coniferous trees (the raw material for natural cellulose fiber) and 990g of deionized water, and stir at 25°C and 100rpm for 30 minutes. Next, add 0.13g of TEMPO, 1.3g of sodium bromide, and 35.5g of 10.5% by mass sodium hypochlorite aqueous solution to 10g of pulp fiber in that order. Then, perform pH stat titration using an automatic titrator and add 0.5M sodium hydroxide aqueous solution dropwise to maintain the pH at 10.5. Allow the reaction to proceed at 25°C for 120 minutes with a stirring speed of 100rpm. Next, while stirring, add 0.01M hydrochloric acid to adjust the pH of the suspension to 2. Finally, filter out the solids by suction filtration. The solids are dispersed in deionized water, and the solids are filtered out by suction filtration. This process is repeated until the conductivity of the filtrate is 200 μs / cm or less. The resulting solids are then dehydrated to obtain anionic modified cellulose fibers.

[0089] [Preparation of short-fiber anion-modified cellulose fibers] Anionically modified cellulose fibers having the physical properties listed in Table 1 were subjected to alkaline hydrolysis to prepare short-fiber anionically modified cellulose fibers having the physical properties listed in Table 2.

[0090] [Table 2]

[0091] Such short-fiber anionic modified cellulose fibers can be prepared, for example, by the following alkaline hydrolysis treatment.

[0092] [Alkaline hydrolysis treatment] A suspension of anionically modified cellulose fibers having the physical properties listed in Table 1, with a solid content of 144.5 g, is diluted with 1000 g of deionized water. 1.4 g of 35% hydrogen peroxide solution is added (1 part by mass of hydrogen peroxide per 100 parts by mass of solid content of the raw cellulose fibers), and the pH is adjusted to 12 with a 1 M sodium hydroxide aqueous solution. Then, alkaline hydrolysis is performed at 80°C for 2 hours (solid content of the anionically modified cellulose fiber suspension is 4.3% by mass). After the suspension is cooled to room temperature, 0.01 M hydrochloric acid is added to adjust the pH of the suspension to 2. The solid content of the suspension is filtered off by suction filtration. The process of dispersing the solid content in deionized water and filtering off the solid content by suction filtration is repeated until the conductivity of the filtrate is 200 μS / cm or less. Deionized water is added to the suspension so that the solid content concentration in the suspension is 5% by mass, the mixture is stirred at 95°C for 12 hours, and then cooled to room temperature to obtain an aqueous suspension of short-fiber anionically modified cellulose fibers. Shortened anion-modified cellulose fibers can be obtained by centrifuging the aqueous suspension of the obtained shortened anion-modified cellulose fibers.

[0093] [Composition containing modified cellulose fibers and resin] (Example 1) Shortened anionic cellulose fibers were added to PGME to obtain a dispersion with a solid content of 2.0% by mass. 4.1 g of EO / PO amine was added to 300 g of the obtained dispersion and stirred at 25°C for 1 hour to obtain a modified cellulose fiber dispersion. 300 g of epoxy resin was then added to the modified cellulose fiber dispersion and stirred at 25°C for 1 hour. The dispersion was then subjected to five treatments at 150 MPa using a high-pressure homogenizer (NanoVeta L-ES, manufactured by Yoshida Machinery Industry Co., Ltd.). Subsequently, PGME was removed from the modified cellulose fiber dispersion using an evaporator to obtain a composition containing modified cellulose fibers and resin.

[0094] (Example 2) A composition containing modified cellulose fibers and resin was obtained by the same procedure as in Example 1, except that 1750 g of a dispersion with a solid content of 2.0% by mass, obtained by adding short-fiber anionic modified cellulose fibers to PGME, 23.7 g of EO / PO amine, and 700 g of epoxy resin were used.

[0095] [Composition containing a curing agent and a curing accelerator] Rubber particles were added to a composition containing modified cellulose fibers and resin, and the mixture was stirred at 25°C and 2000 rpm for 3 minutes, followed by defoaming at 25°C and 2200 rpm for 2 minutes using an automatic orbital stirrer (Sinky Co., Ltd., Awatori Rentaro). Subsequently, a hardening agent and a hardening accelerator were added, and the mixture was stirred at 25°C and 2000 rpm for 3 minutes, followed by defoaming at 25°C and 2200 rpm for 2 minutes using an automatic orbital stirrer (Sinky Co., Ltd., Awatori Rentaro), to obtain the compositions shown in Table 3.

[0096] (Comparative Examples 1-2) The compositions described in Table 3 were obtained by performing the same procedures as in the above examples, except that rubber particles were added to a resin that does not contain modified cellulose fibers, instead of a composition containing modified cellulose fibers and resin.

[0097] [Fabrication of resin film] The compositions listed in Table 3 were applied to copper foil with an applicator (manufactured by Tester Sangyo Co., Ltd.) to a coating thickness of 200 μm, and a resin film was prepared by curing at 130°C for 2 hours.

[0098] [Tensile test] The resin film was punched out into strips measuring 5 x 40 mm and used as a sample. The test was performed using a benchtop precision universal testing machine (Shimadzu Corporation, AGS-X) with a load cell of 1000N, a chuck distance of 20mm, at room temperature (25°C), and a tensile speed of 1mm / min. The thickness of the test specimen was calculated from the average of three points, and the elastic modulus was calculated from the slope of the stress-strain diagram using strains of 5-15 MPa. The results are shown in Table 3.

[0099] [Table 3]

[0100] Comparing Example 1 with Comparative Example 1, and Example 2 with Comparative Example 2, it was found that the elastic modulus of the resulting resin film was higher in the Examples, as was the value of the elongation at the breaking point. From this, it was found that by combining modified cellulose fibers and rubber particles, a high elastic modulus can be imparted to the resulting resin film while maintaining its elongation.

[0101] [reagent] The following reagents and raw materials were used without special purification. Resin: Epoxy resin (manufactured by Mitsubishi Chemical Corporation, jER828, epoxy equivalent = 184-194, weight-average molecular weight = 370) Hardener: Dicyandiamide (manufactured by Mitsubishi Chemical Corporation, DICY) was used, which was pulverized using a mini blender (manufactured by Osaka Chemical Co., Ltd.). The curing accelerator used was 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) (manufactured by Thermo Scientific), which was pulverized using a mini blender (manufactured by Osaka Chemical Co., Ltd.). Rubber particles: Core-shell rubber particles (manufactured by Kaneka Corporation, KaneAce MX-153, 33% by mass of core-shell rubber particles / 67% by mass of bisphenol A type epoxy resin, average particle size 100 nm) PGME: 1-Methoxy-2-propanol (manufactured by Daicel Corporation) EO / PO amine: Methoxypoly(oxyethylene / oxypropylene)-2-propylamine (HUNTSMAN, Jeffermin M2070, Mw=2000, EO:PO=4:1) [Industrial applicability]

[0102] The composition of the present invention exhibits excellent elongation at break and elastic modulus when forming a resin film, and can therefore be used as an adhesive, a molded article, or a material for adhesives.

Claims

1. A composition containing modified cellulose fibers, rubber particles, and a curable resin, The modified cellulose fiber is formed by attaching at least one modifying group selected from the group consisting of hydrocarbon groups, functional groups having a polyoxyalkylene structure, and functional groups having a polysiloxane structure to an anionic modified cellulose fiber. A composition in which the curable resin is an epoxy resin, a urethane resin, a phenoxy resin, a phenolic resin, a urea resin, or a melamine resin.

2. The composition according to claim 1, wherein the mass ratio of rubber particles to curable resin is 0.01 or more and 1 or less.

3. The composition according to claim 1 or 2, wherein the mass ratio of modified cellulose fibers to curable resin is 0.01 / 100 or more and 30 / 100 or less.

4. The composition according to any one of claims 1 to 3, wherein the modified cellulose fiber content is 0.1% by mass or more and 10% by mass or less.

5. The composition according to any one of claims 1 to 4, which is an adhesive composition.

6. A bonding method using the composition described in any one of claims 1 to 5.

7. A molded article containing the composition according to any one of claims 1 to 5.

8. A fiber composite material containing the composition according to any one of claims 1 to 5.

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