JP7029125B2 - Method for manufacturing composite materials - Google Patents

Description

The present invention relates to a method for producing a composite material using cellulose nanofibers.

In recent years, attention has been paid to cellulose nanofibers obtained by defibrating natural cellulose fibers into nano-sized fibers. Natural cellulose fiber is a biomass made from pulp such as wood, and it is expected that the environmental load will be reduced by effectively using it.

Cellulose nanofibers have been offered on the market as an aqueous dispersion, but it has been difficult to process them for compounding with a rubber component or a synthetic resin. Since the cellulose nanofibers form hydrogen bonds and aggregate in the drying step of removing water from the aqueous dispersion, the cellulose nanofibers cannot exist in a highly deflated state in the composite process, and the composite material is used. It could not be sufficiently reinforced by cellulose nanofibers.

Therefore, a method of mixing a cellulose nanofiber aqueous dispersion with a rubber latex or a resin emulsion has been proposed (see Patent Documents 1 and 2).

However, the composite materials produced by these methods may be affected by the properties of the rubber latex or resin emulsion. In addition, it could not be applied to rubber or resin that is not on the market as rubber latex or resin emulsion.

Japanese Unexamined Patent Publication No. 2015-98576 Japanese Unexamined Patent Publication No. 2016-29169

The present invention provides a method for producing a composite material using a fiber material having excellent processability for composite of cellulose nanofibers.

[1] One aspect of the method for producing a composite material is
A step of mixing a cellulose nanofiber aqueous dispersion in which cellulose nanofibers are dispersed in an aqueous solvent, a cationic surfactant, and a polyhydric alcohol to obtain a CNF dispersion.
A drying step of removing an aqueous solvent from the CNF dispersion to obtain a fiber material, and a drying step.
A mixing step of mixing the fiber material with a rubber component to obtain a composite material,
Including
The mass ratio of the cationic surfactant to the cellulose nanofibers in the CNF dispersion is 0.1 to 2.0 times.
The mass ratio of the polyhydric alcohol to the cellulose nanofibers in the CNF dispersion is 2.0 to 20.0 times.

[2] In one aspect of the method for producing a composite material,
The cationic surfactant can be any one or more of a primary to tertiary amine salt and a quaternary ammonium salt.

[3] In one aspect of the method for producing a composite material,
The cationic surfactant can be a quaternary ammonium salt having a long-chain alkyl group having 10 to 18 carbon atoms.

[4] In one aspect of the method for producing a composite material,
The polyhydric alcohol can be at least one of a dihydric alcohol and a trihydric alcohol.

[5] In one aspect of the method for producing a composite material,
In the mixing step, an open roll having a roll interval of more than 0 mm and 0.5 mm or less and a roll temperature of 0 ° C. to 50 ° C. can be used for thinning.

[6] In one aspect of the method for producing a composite material,
The rubber component can be nitrile rubber.

[7] In one aspect of the method for producing a composite material,
The rubber component can be silicone rubber.

[8] In one aspect of the method for producing a composite material,
The rubber component can be styrene-butadiene rubber.

[9] In one aspect of the method for producing a composite material,
A removal step of removing the polyhydric alcohol remaining in the composite material can be further included by heating the composite material obtained in the mixing step in a heating furnace and degassing the inside of the heating furnace.

According to one aspect of the method for producing a composite material, the composite material can be produced using a fiber material having excellent processability for compositing cellulose nanofibers.

It is a flowchart which shows the manufacturing method of the composite material which concerns on one Embodiment. It is a figure which shows typically the mixing process in the manufacturing method of the composite material which concerns on one Embodiment. It is a figure which shows typically the mixing process in the manufacturing method of the composite material which concerns on one Embodiment. It is a figure which shows typically the mixing process in the manufacturing method of the composite material which concerns on one Embodiment. It is a figure which shows the electron micrograph of the tensile fracture cross section of the composite material of Example 3. FIG. It is a figure which shows the electron micrograph of the tensile fracture cross section of the composite material of Example 3. FIG. It is a figure which shows the electron micrograph of the tensile fracture cross section of the composite material of the comparative example 2. It is a figure which shows the electron micrograph of the tensile fracture cross section of the composite material of the comparative example 2. It is a graph which shows the result of the tensile fatigue test of Example 2 and Comparative Example 1.

Hereinafter, a method for producing a composite material and a preferred embodiment of the composite material will be described in detail with reference to the drawings. The embodiments described below do not unreasonably limit the content of the present invention described in the claims. Moreover, not all of the configurations described below are essential constituent requirements of the present invention.

A. Method for Manufacturing Composite Material FIG. 1 is a flowchart showing a method for manufacturing a composite material according to an embodiment.

As shown in FIG. 1, the method for producing a composite material according to the present embodiment includes a step of obtaining a CNF dispersion (S10), a drying step (S12), and a mixing step (S14). More specifically, in the method for producing a composite material according to the present embodiment, a cellulose nanofiber aqueous dispersion in which cellulose nanofibers are dispersed in an aqueous solvent, a cationic surfactant, and a polyhydric alcohol are mixed to form a CNF dispersion. (S10), a drying step (S12) for removing an aqueous solvent from the CNF dispersion to obtain a fiber material, and a mixing step (S14) for mixing the fiber material with a rubber component. The mass ratio of the cationic surfactant to the cellulose nanofibers in the CNF dispersion is 0.1 to 2.0 times, and the mass ratio of the polyvalent alcohol to the cellulose nanofibers in the CNF dispersion is 2. It is 0 to 20.0 times.

A-1. Step of obtaining CNF dispersion liquid (S10)
The step (S10) for obtaining a CNF dispersion is a step of mixing a cellulose nanofiber aqueous dispersion in which cellulose nanofibers are dispersed in an aqueous solvent, a cationic surfactant, and a polyhydric alcohol to obtain a CNF dispersion.

In the step (S10) of obtaining the CNF dispersion liquid, a predetermined amount of the cationic surfactant and the polyhydric alcohol can be added to the cellulose nanofiber aqueous dispersion liquid and mixed by a known stirring means. As the stirring means, those used in the miniaturization step described later can be adopted.

Next, each raw material used in the step (S10) for obtaining the CNF dispersion liquid will be described.

A-1-1. Cellulose nanofibers Cellulose nanofibers are fine fibers of cellulose having an average fiber diameter of 3 nm to 200 nm. Cellulose nanofibers are provided as cellulose nanofiber aqueous dispersions. The aqueous dispersion may contain oxidized cellulose fibers. As the cellulose nanofibers, those obtained by various known methods can also be used. The known raw material for the cellulose nanofibers may be derived from a plant material such as wood, or may be derived from an animal material such as sea squirt or a microorganism such as a bacterium other than the plant material. Further, as a method for producing cellulose nanofibers using a raw material of a vegetable material, for example, the raw material is chemically treated to make it easy to defibrate and then physically treated by a mechanical shearing force to prepare the raw material. The raw material is physically defibrated by a method using a known mechanical high shearing force such as a defibrated product, a high-pressure homogenizer method, a grinder grinding method, a freeze crushing method, a strong shearing force kneading method, and a ball mill crushing method. Shear and manufactured products can be used.

As a method of chemically treating the raw material, an anionic group can be introduced into the cellulose nanofiber as an ionic functional group. Examples of such an ionic functional group include a carboxyl group, a sulfone group, and a group derived from these. As the cellulose nanofibers into which an ionic functional group has been introduced, for example, carboxymethylated CNF (cellulose nanofibers), oxidized CNF described in detail below, and the like can be adopted.

The aqueous dispersion containing the oxidized cellulose fiber can be produced, for example, by an oxidation step of oxidizing the natural cellulose fiber to obtain the oxidized cellulose fiber.

The aqueous dispersion containing the cellulose nanofibers can be obtained by a production method including, for example, an oxidation step of oxidizing natural cellulose fibers to obtain oxidized cellulose fibers and a miniaturization step of refining the oxidized cellulose fibers.

First, in the oxidation step, water is added to the natural cellulose fiber as a raw material and treated with a mixer or the like to prepare a slurry in which the natural cellulose fiber is dispersed in water. Here, examples of natural cellulose fibers include wood pulp, cotton pulp, bacterial cellulose and the like. More specifically, examples of wood pulp include coniferous pulp, hardwood pulp and the like, examples of cotton pulp include cotton linter and cotton lint, and examples of non-wood pulp include cotton linter and cotton lint. Straw pulp, bagus pulp and the like can be mentioned. At least one of these can be used as the natural cellulose fiber.

The natural cellulose fiber has a structure composed of a cellulose microfibril bundle and lignin and hemicellulose filling the space between the bundles. That is, it is presumed that hemicellulose covers the circumference of the cellulose microfibrils and / or the cellulose microfibril bundle, and that the cellulose microfibrils are further covered with lignin. Cellulose microfibrils and / or cellulose microfibril bundles are firmly adhered to each other by lignin to form plant fibers. Therefore, it is preferable that the lignin in the plant fiber is removed in advance from the viewpoint that the aggregation of the cellulose fiber in the plant fiber can be prevented. Specifically, the lignin content in the plant fiber-containing material is usually about 40% by mass or less, preferably about 10% by mass or less. Further, the lower limit of the removal rate of lignin is not particularly limited, and it is preferable that it is close to 0% by mass. The lignin content can be measured by the Klason method.

As the cellulose microfibrils, cellulose microfibrils having a fiber diameter of about 3 nm to 4 nm exist as the smallest unit, and these can be called single cellulose nanofibers. The cellulose nanofibers are those obtained by unraveling natural cellulose fibers and / or oxidized cellulose fibers to the nano-size level, and in particular, the average value of the fiber diameter can be 3 nm to 200 nm, and further can be 3 nm to 150 nm. It can be, in particular, a cellulose microfibril and / or a cellulose microfibril bundle of 3 nm to 100 nm. That is, the cellulose nanofibers can include a single cellulose nanofiber alone or a bundle of a plurality of single cellulose nanofibers. Here, the numerical range indicated by "-" in the present specification includes an upper limit and a lower limit.

The aspect ratio (fiber length / fiber diameter) of the cellulose nanofibers can be 10 to 1000 on average, further 10 to 500, and particularly 100 to 350.

The average value of the fiber diameter and the fiber length of the cellulose nanofibers is an arithmetic mean value measured for at least 50 or more cellulose nanofibers in the field of view of an electron microscope.

Next, in the oxidation step, natural cellulose fibers are oxidized in water using an N-oxyl compound as an oxidation catalyst to obtain oxidized cellulose fibers. As the oxidation step, a known method for oxidizing cellulose can be adopted. Examples of the N-oxyl compound that can be used as an oxidation catalyst for cellulose include 2,2,6,6-tetramethyl-1-piperidin-N-oxyl (hereinafter, also referred to as TEMPO), 4-acetamide-TEMPO, and the like. 4-carboxy-TEMPO, 4-phosphonooxy-TEMPO and the like can be used.

After the oxidation step, for example, a purification step of repeating washing and filtration can be carried out to remove impurities other than the oxidized cellulose fibers contained in the slurry, such as unreacted oxidizing agents and various by-products. The solvent containing the cellulose oxide fiber is, for example, impregnated with water, and at this stage, the cellulose oxide fiber is not defibrated to the unit of the cellulose nanofiber. Water can be used as the solvent, but for example, an organic solvent (alcohols, ethers, ketones, etc.) soluble in water can be used in addition to water depending on the purpose.

The oxidized cellulose fiber has a carboxyl group by modifying a part of the hydroxyl group of the cellulose nanofiber with a substituent having a carboxyl group.

The average value of the fiber diameter of the oxidized cellulose fiber can be 10 μm to 30 μm. The average value of the fiber diameters of the cellulose oxide fibers is an arithmetic mean value measured for at least 50 or more of the cellulose oxide fibers in the field of view of the electron microscope.

Oxidized cellulose fibers can be bundles of cellulose microfibrils. Oxidized cellulose fibers can be defibrated into cellulose nanofibers in the miniaturization step.

In the miniaturization step, the cellulose oxide fibers can be agitated in a solvent such as water, and cellulose nanofibers can be obtained.

In the miniaturization step, the solvent as the dispersion medium can be water. Further, as a solvent other than water, an organic solvent soluble in water, for example, alcohols, ethers, ketones and the like can be used alone or in combination.

The stirring process in the miniaturization process includes, for example, a breaker, a beater, a low-pressure homogenizer, a high-pressure homogenizer, a grinder, a cutter mill, a ball mill, a jet mill, a short-screw extruder, a twin-screw extruder, an ultrasonic stirrer, and a household juicer mixer. Etc. can be used.

Further, the solid content concentration of the solvent containing the oxidized cellulose fiber in the miniaturization treatment can be, for example, 50% by mass or less. If the solid content concentration exceeds 50% by mass, high energy is required for dispersion.

An aqueous dispersion containing cellulose nanofibers can be obtained by the miniaturization step. The aqueous dispersion containing the cellulose nanofibers can be a colorless transparent or translucent suspension. In the suspension, cellulose nanofibers, which are fibers that have been surface-oxidized and defibrated to be finely divided, are dispersed in water. That is, in this aqueous dispersion, the strong cohesive force between microfibrils (hydrogen bonds between surfaces) is weakened by the introduction of carboxyl groups in the oxidation step, and further through the miniaturization step, cellulose nanofibers can be obtained. .. Then, by adjusting the conditions of the oxidation step, the carboxyl group content, polarity, average fiber diameter, average fiber length, average aspect ratio and the like can be controlled. The average value of the fiber diameters of the cellulose nanofibers in the aqueous dispersion thus obtained can be 3 nm to 10 nm, and further can be 3 nm to 4 nm. The average aspect ratio of the cellulose nanofibers in this aqueous dispersion can be 20-350, further 20-250, and in particular 50-200. Further, although the oxidized CNF obtained by the oxidation step has been described here, even a carboxymethylated CNF having an anionic group introduced as an ionic functional group may have the same fiber diameter and aspect ratio as the oxidized CNF. can.

The aqueous dispersion thus obtained can have a solid content of cellulose nanofibers of 0.01% by mass to 5% by mass, preferably 0.1% by mass to 2% by mass. .. If the solid content of the cellulose nanofibers in the aqueous dispersion is less than 0.01% by mass, it takes time for the drying step described later, and if it exceeds 5% by mass, the cationic surfactant cannot be uniformly treated and the cellulose nanofibers. Aggregates are likely to occur. Further, the aqueous dispersion can be, for example, an aqueous dispersion diluted to 1% by mass of the solid content of the cellulose nanofibers. Further, the aqueous dispersion can have a light transmittance of 40% or more, and can have a light transmittance of 60% or more, particularly 80% or more. The transmittance of the aqueous dispersion can be measured as the transmittance at a wavelength of 660 nm using an ultraviolet-visible spectrophotometer.

A-1-2. Cationic Surfactant A cationic surfactant can suppress aggregation due to hydrogen bonds between cellulose nanofibers. The cationic surfactant has an effect of suppressing aggregation of cellulose nanofibers in the fiber material after the drying step. The cationic surfactant can be any one or more of a primary to tertiary amine salt and a quaternary ammonium salt. In particular, the cationic surfactant can be a quaternary ammonium salt having a long-chain alkyl group having 1 to 40 carbon atoms (C number), preferably 2 to 20, and more preferably 8 to 18 carbon atoms. The salt can be chloride, bromide or the like.

Examples of the quaternary ammonium salt having a long-chain alkyl group having 1 to 40 carbon atoms include octyltrimethylammonium chloride, decyltrimethylammonium chloride, dodecyltrimethylammonium chloride, tetradecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, and chloride. Trimethylammonium salts such as octadecyltrimethylammonium; pyridinium salts such as octylpyridinium chloride, decylpyridinium chloride, dodecylpyridinium chloride, tetradecylpyridinium chloride, hexadecylpyridinium chloride, octadecylpyridinium chloride; benzalconium chloride, benzethonium chloride, benzyltri chloride Examples thereof include alkylammonium, dialkyldimethylammonium chloride, trimethylstearylammonium chloride, dodecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide and the like.

The mass ratio of the cationic surfactant to the cellulose nanofibers in the CNF dispersion is 0.1 to 2.0 times. If the mass ratio of the cationic surfactant to the cellulose nanofibers is 0.1 times or more, it can act on the carboxyl group on the surface of the cellulose nanofibers to suppress the reaggregation of the cellulose nanofibers, which is good in the rubber component. A defibrated state can be obtained. When the mass ratio of the cationic surfactant to the cellulose nanofibers in the CNF dispersion exceeds 2.0 times, the amount of the surfactant in the composite increases, the processability deteriorates, and the physical characteristics of the composite material deteriorate. do. Furthermore, the mass ratio of the cationic surfactant to the cellulose nanofibers can be 0.1 to 1.0 times. If the mass ratio is 1.0 times or less, the workability in the mixing step described later can be excellent.

A-1-3. Polyhydric alcohol The polyhydric alcohol can suppress the reaggregation of the cellulose nanofibers after dehydration drying by hindering the hydrogen bonding between the cellulose nanofibers even if the aqueous solvent is removed in the drying step described later. Therefore, the polyhydric alcohol exerts a function as a substitute material for the aqueous solvent of the CNF dispersion liquid. In addition, it is possible to facilitate the defibration of cellulose nanofibers in the mixing step. The polyhydric alcohol is an alcohol excluding the monohydric alcohol. Since monohydric alcohol has a lower boiling point than water, it cannot be used.

Multivalent alcohols have a higher boiling point than water. By having a boiling point higher than that of water, the polyhydric alcohol can remain in the fiber material even if the water evaporates through the drying step described later. Further, since the surfactant is adsorbed on the cellulose nanofibers, the cellulose nanofibers do not aggregate with each other and can maintain a stable dispersed state. It is desirable that the polyhydric alcohol has a boiling point higher than the kneading temperature in the mixing step described later. This is to prevent the polyhydric alcohol from rapidly evaporating in the mixing step and causing reaggregation of the cellulose nanofibers.

The polyhydric alcohol is preferably at least one of a dihydric alcohol and a trihydric alcohol. Examples of the dihydric alcohol include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, neopentyl glycol and the like. Examples of the trihydric alcohol include glycerin, trimethylolethane, trimethylolpropane, cyclohexanedimethanol and the like. As the polyhydric alcohol other than divalent and trivalent, for example, pentaerythritol, diglycerin, polyglycerin and the like may be contained.

The mass ratio of the polyhydric alcohol to the cellulose nanofibers in the CNF dispersion is 2.0 to 20.0 times. If the mass ratio of the polyvalent alcohol to the cellulose nanofibers is 2 times or more, the cellulose nanofibers can be defibrated when compounded with the rubber component using the fiber material after the drying step, and if it is 20 times or more. For example, processing becomes difficult at the time of compounding. Further, the mass ratio of the polyvalent alcohol to the cellulose nanofibers can be 2.5 times to 10.0 times, and the mass ratio of the polyvalent alcohol to the cellulose nanofibers is 2.5 times or more and less than 10.0 times. Can be.

A-2. Drying step (S12)
The drying step (S12) is a step of removing an aqueous solvent from the CNF dispersion obtained in the step of obtaining the CNF dispersion to obtain a fiber material. As a method for removing the aqueous solvent from the CNF dispersion liquid, a known method can be used, and for example, it may be dried by heating or may be dried by a spray drying method.

For example, the CNF dispersion is poured into a container (such as a vat), and the container is placed in an oven to evaporate the aqueous solvent at 30 ° C to 100 ° C.

In the drying step (S12), the aqueous solvent may be completely removed from the CNF dispersion, or a small amount of the aqueous solvent may be left so that it can be removed in the mixing step described later.

A-2-1. Fiber material The fiber material obtained by the drying step contains cellulose nanofibers, a cationic surfactant and a polyhydric alcohol, and the mass ratio of the polyvalent alcohol to the cellulose nanofibers is 2.0 to 20.0 times. Is. The cationic surfactant prevents aggregation of the cellulose nanofibers due to hydrogen bonds, and the polyhydric alcohol can facilitate the defibration of the cellulose nanofibers in the mixing step described later. Therefore, by using the fiber material in the method for producing a composite material, it is possible to improve the processability for compositing the cellulose nanofibers.

A-3. Mixing step (S14)
The mixing step (S14) is a step of mixing the fiber material with the rubber component. In the mixing step (S14), an open roll having a roll interval of more than 0 mm and 0.5 mm or less and a roll temperature of 0 ° C. to 50 ° C. can be used for thinning.

First, before the thinning step, as shown in FIG. 2, the rubber component 30 wound around the first roll 10 can be kneaded, and the molecular chain of the rubber component 30 is appropriately cut to be free. Generates radicals. The free radicals of the rubber component 30 generated by the kneading are in a state where they are easily combined with the cellulose nanofibers.

As the rubber component 30, natural rubber (NR) or synthetic rubber can be used. Examples of synthetic rubber include styrene-butadiene rubber (SBR), nitrile rubber (NBR), chloroprene rubber (CR), ethylene propylene rubber (EPDM), butyl rubber (IIR), chlorobutyl rubber (CIIR), and acrylic rubber (ACM). , Silicone rubber (Q), Fluorine rubber (FKM), butadiene rubber (BR), epoxidized butadiene rubber (EBR), epichlorohydrin rubber (CO, CEO), urethane rubber (U), polysulfide rubber (T), etc. A mixture can be used.

The rubber component 30 can be a nitrile rubber. Nitrile rubber includes hydrogenated nitrile rubber (H-NBR). The hydrogenated nitrile rubber may be referred to as hydrogenated nitrile rubber, hydrogenated acrylonitrile-butadiene rubber, or the like. The hydride nitrile rubber can be obtained by hydrogenating the double bond contained in the nitrile rubber. A composite material using nitrile rubber as the rubber component 30 has excellent rigidity because the rubber component 30 is reinforced by defibrated cellulose nanofibers, and has excellent properties such as 50% modulus and 100% modulus in a tensile test. .. Among the nitrile rubbers, the composite material using hydrogenated nitrile rubber as the rubber component 30 has excellent tensile strength in, for example, a tensile test.

The rubber component 30 can be a silicone rubber. The silicone rubber can be a raw rubber of organopolysiloxane, the main chain is composed of siloxane bonds, and the side chains are alkyl groups such as methyl group, ethyl group, propyl group and butyl group, and cycloalkyl such as cyclohexyl group. Bonded to an alkenyl group such as a group, a vinyl group, an allyl group, a butenyl group, a hexenyl group, an aryl group such as a phenyl group or a trill group, an aralkyl group such as a benzyl group or a γ-phenylpropyl group, or a carbon atom of these groups. It can have a group in which a part or all of the hydrogen atom is substituted with a halogen atom, a cyano group or the like, for example, a chloromethyl group, a trifluoropropyl group, a cyanoethyl group or the like. The molecular structure of the silicone rubber can be linear and can be linear with some branches. A composite material using silicone rubber as the rubber component 30 has excellent properties in tensile strength, rigidity, and fracture energy in a tensile test because the rubber component 30 is reinforced by defibrated cellulose nanofibers.

A known cross-linking agent can be used for the silicone rubber. For example, a condensation type reaction, an addition type reaction, or a peroxide reaction can be used as the cross-linking form, and peroxide cross-linking is preferable. By cross-linking the silicone rubber with a cross-linking agent, a composite material having excellent heat resistance and chemical resistance can be produced.

Further, the silicone rubber contains a silicone rubber compound in which silica is pre-blended. Commercially available silicone rubber usually contains silica. Silicone rubber is characterized by having excellent properties at a wide range of temperatures from low temperature to high temperature, but since it has low physical strength, a compound containing silica particles in advance is generally used.

The rubber component 30 can be styrene-butadiene rubber. A composite material using styrene-butadiene rubber as the rubber component 30 has excellent properties in tensile strength, rigidity, and fracture energy in a tensile test because the rubber component 30 is reinforced by defibrated cellulose nanofibers.

Next, as shown in FIG. 3, a step of gradually putting the fiber material 80 into the bank 34 of the rubber component 30 wound around the first roll 10 and kneading the fibers to obtain an intermediate mixture can be performed. In the step of obtaining the intermediate mixture, in addition to the fiber material 80, for example, a cross-linking agent, a vulcanizing agent, a vulcanization accelerator, a vulcanization retarder, a softening agent, a plasticizer, a curing agent, a reinforcing agent, a filler, and an antiaging agent. Agents, colorants, acid acceptors, coupling agents and the like can be included. The compounding agents other than these cellulose nanofibers can be added to the rubber component 30 at an appropriate time in the mixing process.

The step of obtaining the intermediate mixture of FIGS. 2 and 3 is not limited to the open roll method, and for example, a closed kneading method or a multi-screw extrusion kneading method can also be used.

Further, as shown in FIG. 4, a thinning step can be performed. The thinning step is a step of thinning at 0 ° C. to 50 ° C. using an open roll 2 having a roll interval d of more than 0 mm and set to 0.5 mm or less to obtain an uncrosslinked composite material 50. Can be done. The roll interval d is a set value, and if the intermediate mixture 36 can enter a slight gap between rolls, the intermediate mixture 36 may be extruded from the slight gap. In this step, the roll spacing d between the first roll 10 and the second roll 20 is set to, for example, a spacing of 0.1 mm to 0.5 mm, and the intermediate mixture 36 obtained in FIG. 3 is used as the open roll 2. It can be thrown in and thinly threaded once or multiple times. The number of thinnings can be, for example, about 1 to 10 times. Assuming that the surface speed of the first roll 10 is V1 and the surface speed of the second roll 20 is V2, the surface speed ratio (V1 / V2) of both in thinning is 1.05 to 3.00. It can be 1.05 to 1.2. By using such a surface velocity ratio, a desired shearing force can be obtained.

The composite material 50 extruded from such a narrow roll is greatly deformed as shown in FIG. 5 by the restoring force due to the elasticity of the rubber component, and at that time, the cellulose nanofibers move greatly together with the rubber component. The composite material 50 obtained through thinning is rolled by a roll and dispensed into a sheet having a predetermined thickness, for example, 100 μm to 500 μm.

In this thinning step, in order to obtain the highest possible shearing force, the roll temperature can be set to, for example, 0 ° C to 50 ° C, and further set to a relatively low temperature of 5 ° C to 30 ° C. Can be done. The measured temperature of the composite material 50 can also be adjusted to 0 ° C to 50 ° C, and further can be adjusted to 5 ° C to 30 ° C.

By adjusting to such a temperature range, the cellulose nanofibers can be defibrated by utilizing the elasticity of the rubber component, and the defibrated cellulose nanofibers can be dispersed in the composite material 50.

Due to the high shearing force in this thinning step, a high shearing force acts on the rubber component, and the cellulose nanofibers in the fiber material are separated from each other so as to be pulled out one by one to the molecules of the rubber component and dispersed in the rubber component. Will be done. Here, since the fiber material contains polyhydric alcohol to suppress the aggregation of cellulose nanofibers, and the cationic surfactant bound to the cellulose nanofibers suppresses the aggregation due to hydrogen bonding between the cellulose nanofibers, the cellulose nanofibers Is deflated and dispersed in the rubber component. In particular, since the rubber component has elasticity and viscosity, cellulose nanofibers can be defibrated and dispersed. Then, it is possible to obtain a composite material 50 having excellent dispersibility and dispersion stability of the cellulose nanofibers (the cellulose nanofibers are less likely to reaggregate).

More specifically, when the rubber component and the cellulose nanofibers are mixed with an open roll, the viscous rubber component penetrates into each other of the cellulose nanofibers. When the surface of the cellulose nanofibers is moderately active, for example, by an oxidation treatment, it can be particularly easily bonded to the molecules of the rubber component. Next, when a strong shearing force acts on the rubber component, the cellulose nanofibers also move with the movement of the molecules of the rubber component, and further, the cellulose nanofibers aggregated due to the restoring force of the rubber component due to the elasticity after shearing. It will be separated and dispersed in the rubber component. In particular, the open roll method is preferable because it can measure and control the actual temperature of the mixture as well as control the roll temperature.

The rubber component contains polar and reactive functional groups such as carboxyl groups, hydroxyl groups, amino groups, epoxy groups, acrylic groups, methacrylic groups, to enhance interaction with cellulose nanofibers treated with cationic surfactants. And can be a modified rubber component having a reactive functional group selected from these combinations. Examples of such a rubber component include carboxy-modified NBR.

In the mixing step, the composite material may be used as a masterbatch and mixed with the polymer substance to be a matrix.

A-4. Removal Step The method of manufacturing a composite material may further include a removal step. The removal step is a step of removing the polyhydric alcohol from the composite material. The removal step can be performed by heating the composite material. The heating temperature in the removal step can be higher than the temperature at which the polyhydric alcohol used in the composite material evaporates. In the removing step, the polyhydric alcohol remaining in the composite material can be removed by heating the composite material obtained in the mixing step (S14) in the heating furnace and degassing the inside of the heating furnace. For degassing in the heating furnace, the air in the furnace may be sucked by a vacuum pump or the like connected to the heating furnace to promote evaporation of the polyhydric alcohol. The heating temperature in the removal step can be equal to or lower than the temperature at which the rubber component does not deteriorate. Further, the heating temperature in the removal step can be lower than the temperature at which the cellulose nanofibers do not discolor. For example, the temperature may be set so that the weight of the cellulose nanofibers does not decrease by 5% or more in the thermal weight measurement (TG: Thermo Gravity measurement) so that the rubber component and the cellulose nanofibers do not deteriorate.

For the heat treatment in the removal step, for example, a vacuum oven or the like can be used. The removing step may be performed by raising the temperature of the roll to the heating temperature in the removing step and continuing the kneading for a predetermined time after the mixing step (S14).

A-5. Molding step It can be molded using the composite material obtained in the mixing step (S14) or the removing step. The molding step is, for example, press working, compression molding, extrusion molding, etc., which are common for molding rubber compositions.

In the molding step, the composite material obtained in the mixing step (S14) can be pressed while being heated in the mold, and the composite material can be molded by degassing the inside of the mold. Further, in the molding step, the composite material obtained in the removal step can be further heated and pressurized in the mold, and the composite material can be molded by degassing the inside of the mold. By degassing the inside of the mold, the polyhydric alcohol remaining in the composite material can be removed. For degassing in the mold, the air in the furnace may be sucked by a vacuum pump or the like connected to the heating furnace to promote the evaporation of the polyhydric alcohol.

Prior to the molding step, known additives to be incorporated into the rubber composition may be mixed with the composite material. For example, cross-linking agents, vulcanizing agents, vulcanization accelerators, vulcanization retarders, softeners, plasticizers, curing agents, reinforcing agents, fillers, anti-aging agents, coloring agents, acid receiving agents, coupling agents, etc. Can include.

B. Composite material The composite material according to the present embodiment contains cellulose nanofibers and a cationic surfactant in the rubber component, and 5.0 parts by mass to 40.0 parts by mass of the cellulose nanofibers with respect to 100 parts by mass of the rubber component. The mass ratio of the cationic surfactant to the cellulose nanofibers is 0.1 to 2.0 times.

The rubber component can be reinforced by the composite material containing 5.0 parts by mass or more of defibrated cellulose nanofibers with respect to 100 parts by mass of the rubber component. In addition, the inclusion of cellulose nanofibers, which are biomass, reduces the environmental load of composite materials. When the composite material contains 40.0 parts by mass or less of defibrated cellulose nanofibers with respect to 100 parts by mass of the rubber component, the processing by the above-mentioned mixing step (S14) can be performed. Further, the blending amount of the cellulose nanofibers with respect to 100 parts by mass of the rubber component in the composite material can be 5.0 parts by mass to 30.0 parts by mass.

The cellulose nanofibers contained in the composite material can have an average fiber diameter of 3 nm to 200 nm. When the average value of the fiber diameter of the cellulose nanofibers is 3 nm or more, it is available on the market, and when the average value is 200 nm or less, the rubber component 30 can be reinforced by adding a small amount.

The composite material can be free of agglomerates of cellulose nanofibers having a maximum width of 10 μm or more, and can be free of agglomerates of cellulose nanofibers having a maximum width of 5 μm or more, particularly 1 μm or more. It can be free of agglomerates with maximum width. Further, since the composite material does not contain a large agglomerate of 10 μm or more, it is possible to achieve both high flexibility and reinforcing property without breaking at an early stage during deformation.

In the composite material, the rubber component in the composite material can be nitrile rubber. In the composite material, the rubber component in the composite material can be silicone rubber. In the composite material, the rubber component in the composite material can be styrene-butadiene rubber.

Cellulose nanofiber agglomerates are scattered in a matrix in which a plurality of cellulose nanofibers are gathered together and aggregated in the form of particles. The maximum width of the cellulose nanofiber agglomerates can be determined by observing the composite material sheet with a transmission optical microscope and the particulate agglomerates scattered in the matrix material by observing the fracture surface of the composite material with a scanning electron microscope. Measure the maximum width.

By containing the defibrated cellulose nanofibers in the composite material, the hydrophilicity on the surface of the composite material is improved and the adhesiveness is improved.

In the present invention, some configurations may be omitted, or each embodiment or modification may be combined within the range having the features and effects described in the present application.

The present invention includes substantially the same configurations as those described in the embodiments (configurations having the same function, method and result, or configurations having the same purpose and effect). The present invention also includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. Further, the present invention includes a configuration having the same action and effect as the configuration described in the embodiment or a configuration capable of achieving the same object. Further, the present invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

(1) Preparation of Samples of Examples 1 to 9 Step of obtaining CNF dispersion: Cellulose nanofibers by diluting cellulose nanofibers aqueous dispersion (2% concentration TEMPO oxidized cellulose nanofibers manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) with water. As a 1% concentration aqueous dispersion (solvent is water), add polyhydric alcohol to the aqueous dispersion, use a juicer mixer (Warning Blender MX1200XTX), and stir at a rotation speed of 20,000 rpm for 15 seconds. Mixed in. Further, a cationic surfactant was added to this mixture, and the mixture was stirred at a rotation speed of 20,000 rpm for 15 seconds using the same juicer mixer to obtain a CNF dispersion.

In Tables 1 to 3,
"H-NBR": Hydrogenated nitrile rubber, Zeon Corporation Zetpol2230LX, center value of nitrile amount 33.2%, iodine value 36 mg / 100 mg, solid content concentration 40.5%, carboxy-modified H-NBR latex dried. Used as solid rubber,
"CNF": TEMPO oxidized cellulose nanofibers (average fiber diameter of cellulose nanofibers is 3.3 nm, average aspect ratio is 160),
"K1": ACROS ORGANICS, dodecyltrimethylammonium chloride, 98% concentration,
"K2": manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., hexadecyltrimethylammonium chloride, 95% concentration,
"K3": manufactured by Tokyo Chemical Industry Co., Ltd., trimethylstearylammonium chloride, 98% concentration,
"DEG": Fuji Film Wako Pure Chemical Industries, Ltd., diethylene glycol, special grade,
"THF": manufactured by Wako Pure Chemical Industries, Ltd., tetrahydrofuran, special grade,
Met.

In Tables 1 to 5, the blending amount of the cationic surfactant and the polyhydric alcohol in the fiber material is the mass of each material when the blending amount (mass) of the cellulose nanofibers in each example is "1". Shown as a ratio. Therefore, for example, when the ratio of the cationic surfactant is "0.5", the amount of the cationic surfactant is 2.5 parts by mass (phr) when the blending amount of CNF in the composite material is 5.0 parts by mass (phr). ). Further, in Tables 1 to 5, the blending amount of CNF in the composite material is CN when the rubber component (H-NBR) is 100 parts by mass (phr).
The mass part of F and the mass part of the cationic surfactant are shown.

Drying step: An aqueous solvent was removed from the CNF dispersion to obtain a fiber material. More specifically, the CNF dispersion was poured into a vat and dried in an oven at 50 ° C. for 24 hours to remove the aqueous solvent to obtain a fiber material.

Mixing step: H-NBR as a rubber component of Tables 1 and 2 is wound around an open roll (two rolls), the fiber material is gradually charged into the H-NBR wound around the roll, and the H-NBR is combined with the open roll. The fiber material was kneaded to obtain an intermediate mixture, and the intermediate mixture was thinly passed through (roll temperature 10 ° C. to 30 ° C., roll interval 0.3 mm, roll speed ratio 1.1) to obtain a composite material.

Here, in Examples 1 to 4, the blending amount of CNF was changed from 5.0 parts by mass to 30.0 parts by mass using the fiber materials having the same blending. In Examples 5 to 9, the composition of the fiber material was changed. Specifically, in Example 5, the ratio of the cationic surfactant to CNF1 was 0.2, which was smaller than the ratio of the cationic surfactant in Examples 1 to 4. In Example 6, the cationic surfactant was set to 1 with respect to CNF 1, and a larger amount than the ratio of the cationic surfactant of Examples 1 to 4 was blended. In Example 7, the DEF was set to 10 with respect to CNF 1, and the ratio was higher than the ratio of DEF in Examples 1 to 4. In Example 8, the cationic surfactant was hexadecyltrimethylammonium chloride, and the ratio was 0.5. In Example 9, the cationic surfactant was trimethylstearylammonium chloride, and the ratio was 0.5.

Removal step: The composite material was placed in a vacuum oven and heated at 100 ° C. for 4 hours to remove the polyhydric alcohol.

Molding step: The composite material was reintroduced into the open roll and compounded with a cross-linking agent and other additives. The composite material to which the cross-linking agent was added was pressure-molded under vacuum at 165 ° C. for 30 minutes to obtain a sheet-shaped sample of each example having a thickness of 1 mm.

(2) Preparation of Samples of Comparative Examples 1 to 5 The samples of Comparative Examples 1 to 5 were prepared according to the blending amounts in Table 3.

In Comparative Example 1, a sample was obtained by press molding in the same manner as in Example 1 using H-NBR which is a rubber component used in Examples 1 to 9.

In Comparative Example 2, the mixing step was carried out in the same manner as in Example 3 except that the cationic surfactant was 3 times that of CNF.

In Comparative Example 3, a test piece was obtained in the same manner as in Example 3 except that the polyhydric alcohol was 0.5 times that of CNF.

In Comparative Example 4, the mixing step was carried out in the same manner as in Example 3 except that the polyhydric alcohol was 50 times that of CNF, but the test piece was not wrapped around the roll and no test piece was obtained.

In Comparative Example 5, a test piece was obtained in the same manner as in Example 3 except that tetrahydrofuran, which is a solvent other than the polyhydric alcohol, was used instead of the polyhydric alcohol.

(3) Evaluation method (3-1) Hardness measurement For the samples of Examples and Comparative Examples, the rubber hardness (Hs (JIS A)) is JIS K.
Measured based on the 6253 test. The measurement results are shown in Tables 1 to 3.

(3-2) Tensile test For the samples of Examples and Comparative Examples, the test pieces punched into the dumbbell shape of JIS No. 6 were used at 23 ± 2 ° C. using a tensile tester of Autograph AG-X manufactured by Shimadzu Corporation. Tensile test was conducted based on JIS K6251 with a distance between marked lines of 20 mm and a tensile speed of 500 mm / min. Tensile strength (TS (MPa)), elongation during cutting (Eb (%)), 50% modulus (σ50 (MPa)) ) And 100% modulus (σ50 (MPa)) were measured. The measurement results are shown in Tables 1 to 3.

(3-3) Tear test Samples of Examples and Comparative Examples are punched into an angled test piece without a notch, and using an Autograph AG-X manufactured by Shimadzu Corporation, a tensile speed of 500 mm / min is compliant with JIS K6252. A tear test was performed, the maximum tear force (N) was measured, and the measurement result was divided by the thickness of the test piece of 1 mm to calculate the tear strength (Tr (N / mm)). The measurement results are shown in Tables 1 to 3.

(3-4) Measurement of Linear Expansion Coefficient For the samples of Examples and Comparative Examples, the average value (ppm (1 / K)) of the linear expansion coefficient (CTE) in the measurement temperature range was measured. The measuring device is a thermomechanical analyzer TMA / SS6100 manufactured by SII, the measurement sample shape is 20 mm × 2 mm × 1 mm (chuck spacing 10 mm), the tension mode is 25 kPa, the temperature rise rate is 10 ° C / min, and the measurement temperature is 20 ° C ( The average linear expansion coefficient from room temperature) to 100 ° C. was measured. The measurement results are shown in Tables 1 to 3.

(3-5) Workability Evaluation For the samples of Examples and Comparative Examples, the workability in the above mixing step when H-NBR was prototyped at 100 g was evaluated. Evaluation result ("○" was given when the roll wrapping property was good and the kneading time was within 2 hours, indicating that the workability was good. The roll wrapping property was good and the kneading time was good. When the time was 2 hours or more, it was marked with "△" to indicate that processing was possible. The roll wrapping property was poor (for example, the rubber slipped around the roll and did not wrap, and passed between the rolls. When the rubber was not connected, etc.) and the kneading time was 2 hours or more, an "x" was given to indicate that the processing could not be performed.) Are shown in Tables 1 to 3.

(3-6) Evaluation of defibration and dispersibility For the samples of Examples and Comparative Examples, the tensile fracture surface of each sample was observed with a scanning electron microscope of JSM-7400F manufactured by JEOL Ltd., and the defibration and dispersion were observed. Sexual evaluation was performed. The evaluation results (◯ is the case without agglomerates having a maximum width of 10 μm or more, × is the case with agglomerates having a maximum width of 10 μm or more) are shown in Tables 1 to 3. In addition, no agglomerates having a maximum width of 5 μm or more were found in the samples of Examples 1 to 33. Further, the electron micrographs of Example 3 are shown in FIGS. 5 and 6 as samples of “◯”, and the electron micrographs of Comparative Example 2 are shown in FIGS. 7 and 8 as samples of “×”. 5 and 7 were 1000 times, and 6 and 8 were 10000 times.

(3-7) Tensile Fatigue Test The samples of Examples and Comparative Examples were punched into a strip-shaped test piece of 20 mm × width 4 mm × thickness 1 mm (long side is in the columnar direction), and the center of the long side of the test piece. Make a 1 mm deep notch with a razor blade in the width direction from the top, and use a thermomechanical analyzer TMA / SS6100 tester manufactured by SII to hold the short sides of both ends of the test piece with a chuck (between chucks). The distance was 10 mm), a fatigue test was performed by repeatedly applying stress under the condition of a frequency of 1 Hz in an air atmosphere of 120 ° C., and the number of times until the test piece was broken by the stress was measured by applying multiple types of stress. did. The measurement results are shown in FIG. The horizontal axis of FIG. 9 is the linear pressure (N / mm) which is the stress, and the vertical axis is the number of times (times) until the fracture.

(4) Evaluation The tensile strength (TS) of Examples 1 to 9 was larger than that of Comparative Example 1.

Examples 1 to 7 were superior to Comparative Example 1 in the values of 50% modulus (σ50), 100% modulus (σ100), tear strength (Tr), and linear expansion coefficient.

Examples 8 and 9 used different cationic surfactants from Example 3, but the same evaluation as in Example 3 was obtained.

Examples 1 to 9 were superior in defibration and dispersibility as compared with Comparative Examples 2, 3 and 5. The samples of Examples 1 to 9 did not have agglomerates having a maximum width of 10 μm or more. As shown in FIGS. 5 and 6, electron micrographs showed no mass larger than 10 μm. The samples of Comparative Examples 2, 3 and 5 had agglomerates of 10 μm or more. As shown in FIGS. 7 and 8, a large number of large CNF masses having an agglomerate width of more than 10 μm were found in the electron micrographs. In Comparative Example 4, the sample could not be evaluated because it was difficult to knead with an open roll.

Examples 1 to 6, 8 and 9 were superior in workability as compared with Comparative Examples 2 to 5. In Example 7, since the blending amount of the polyhydric alcohol was larger than in Examples 1 to 6, 7, and 8, the mixture tended to be less likely to wrap around the open roll, but compared with Comparative Examples 2 and 4, in Example 7. The workability was excellent.

According to FIG. 9, in Example 2, due to the defibrated CNF, the number of times until fracture was increased by one order of magnitude or more at the same linear pressure.

(5) Preparation of Samples of Examples 10 to 15 The steps of obtaining the CNF dispersion, the drying step, the mixing step, the removing step, and the molding step are the same as in Example 1 according to the formulations shown in Tables 4 and 5. Samples of ~ 15 composite materials were obtained.

In Tables 4 and 5,
"NBR": ternary copolymer XNBR (Carbosiki-modified NBR), Nippon Zeon Corporation Nipol NX775, nitrile amount 26.7%, Mooney viscosity 44.0,
"EG": Tokyo Chemical Industry Co., Ltd., ethylene glycol,
Met. In addition, "CNF", "K1" and "DEG": were the same as in Example 1.

In Examples 10 to 15, different rubber components from those in Examples 1 to 9 were adopted. In Examples 10 to 12, the blending amount of CNF was changed from 5.0 parts by mass to 20.0 parts by mass using the same fiber material. In Example 13, a composite material was obtained in the same manner as in Example 12, except that the polyhydric alcohol was 5 times that of CNF. In Example 14, hexadecyltrimethylammonium chloride was used as the cationic surfactant, and a composite material was obtained in the same manner as in Example 13 except for the above. In Example 15, ethylene glycol was used as the polyhydric alcohol, and the other composite materials were obtained in the same manner as in Example 12.

(6) Preparation of Samples of Comparative Examples 6 and 7 The samples of Comparative Examples 6 and 7 were prepared according to the blending amounts in Table 5.

In Comparative Example 6, a sample was obtained by press molding in the same manner as in Example 10 using NBR which is a rubber component used in Examples 10 to 15.

In Comparative Example 7, a test piece was obtained in the same manner as in Example 12 except that the polyhydric alcohol was 1.5 times as much as CNF.

(7) Evaluation Method The above evaluation test (3) was performed on Examples 10 to 15 and Comparative Examples 6 and 7 under the same conditions as in Example 1.

(8) Evaluation In Example 10, the values of 50% modulus (σ50) and 100% modulus (σ100) were larger than those of Comparative Example 6. In Example 11, the values of 50% modulus (σ50) and 100% modulus (σ100) were larger than those of Comparative Example 6.

In Examples 12 to 15, the values of tensile strength (TS), 50% modulus (σ50) and 100% modulus (σ100) were larger than those of Comparative Examples 6 and 7.

Examples 10 to 15 were superior in defibration and dispersibility as compared with Comparative Examples 6 and 7. Further, Examples 10 to 15 were superior in processability as compared with Comparative Example 7.

(9) Preparation of Samples of Examples 16 to 25 The steps of obtaining the CNF dispersion, the mixing step, the removing step and the molding step are the same as those of Example 1 according to the formulations shown in Tables 6 and 7, and the drying step is as follows. A sample of the composite material of Examples 16 to 25 was obtained.

Drying step: The CNF dispersion was poured into a vat and dried in an oven at 40 ° C. for 3 days to remove an aqueous solvent to obtain a fiber material.

In Tables 6 to 8,
"Silicone rubber": Shin-Etsu Chemical Co., Ltd., KE-551-U,
Met. In addition, "CNF", "K1", "K3" and "DEG": were the same as in Examples 1-9.

In Examples 16 to 25, different rubber components from those in Examples 1 to 9 were adopted. In Examples 16 to 18, the blending amount of CNF was changed from 5.0 parts by mass to 20.0 parts by mass using the same fiber material. In Example 19, a composite material was obtained in the same manner as in Example 18 except that the cationic surfactant was trimethylstearylammonium chloride. In Examples 20 to 22, a composite material was obtained in the same manner as in Example 18 except that the blending amount of the polyhydric alcohol was changed. In Examples 23 and 24, a composite material was obtained in the same manner as in Example 18 except that the blending amount of the cationic surfactant was changed. In Example 25, a composite material was obtained in the same manner as in Example 18 except that the blending amount of the polyhydric alcohol was changed.

(10) Preparation of Samples of Comparative Examples 8 to 13 The samples of Comparative Examples 8 to 13 were prepared according to the blending amounts in Table 8.

In Comparative Example 8, a sample was obtained by press molding in the same manner as in Example 16 using the silicone rubber which is the rubber component used in Examples 16 to 25. Comparative Example 9 obtained a test piece in the same manner as in Example 18 except that it did not contain a polyhydric alcohol. In Comparative Example 10, the mixing step was carried out in the same manner as in Example 18 except that it did not contain a surfactant, but it did not wrap around the roll and no test piece was obtained. In Comparative Examples 11 and 12, each manufacturing process was carried out in the same manner as in Example 18 except that the blending amount of the polyhydric alcohol was changed. Finally, a test piece was obtained. In Comparative Example 13, the mixing step was carried out in the same manner as in Example 18 except that the blending amount of the surfactant was changed, but the test piece was not wrapped around the roll and a test piece could not be obtained.

(11) Evaluation Method The above evaluation test (3) was carried out on Examples 16 to 25 and Comparative Examples 8, 9 and 12 under the same conditions as in Example 1. In Examples 16 to 25 and Comparative Examples 8, 9 and 12, the fracture energy was calculated and evaluated from the results of the tensile test.

(12) Evaluation In Examples 16 to 25, the values of tensile strength (TS), 50% modulus (σ50), 100% modulus (σ100) and fracture energy were larger than those of Comparative Example 8. In Examples 21 and 22 and 25 in which the amount of polyhydric alcohol was higher than that in Example 18, the processability was deteriorated. In Example 24, in which the amount of surfactant was larger than that in Example 18, the processability was lowered.

In Comparative Examples 9 and 12, the defibration and dispersibility of the cellulose nanofibers were low because the polyhydric alcohol was not blended or was too small.

(13) Preparation of Samples of Examples 26 to 33 The steps of obtaining the CNF dispersion, the drying step, the mixing step, the removing step, and the molding step are the same as those of Example 16 according to the formulations shown in Tables 9 and 10. -33 CNF dispersions were obtained.

In Tables 9 to 11,
"SBR": Emulsion-polymerized styrene-butadiene rubber manufactured by JSR Corporation, JSR-1500,
"Modified SBR": Modified solution-polymerized styrene-butadiene rubber manufactured by Asahi Kasei Corporation, Toughden E580 ("Toughden" is a registered trademark),
Met. In addition, "CNF", "K1", "K3" and "DEG": were the same as in Examples 1-9.

In Examples 26 to 33, different rubber components from those in Examples 1 to 9 were adopted. In Examples 26 to 28, the blending amount of CNF was changed from 5.0 parts by mass to 20.0 parts by mass by using the same fiber material. In Examples 29 and 30, a composite material was obtained in the same manner as in Example 28 using two types of styrene-butadiene rubber as the rubber component. In Example 30, a composite material was obtained in the same manner as in Example 29 except that the cationic surfactant was trimethylstearylammonium chloride. In Examples 31 and 32, a composite material was obtained in the same manner as in Example 28 except that the blending amount of the cationic surfactant was changed. In Example 33, a composite material was obtained in the same manner as in Example 28 except that the blending amount of the polyhydric alcohol was changed.

(14) Preparation of Samples of Comparative Examples 14 to 20 The samples of Comparative Examples 14 to 20 were prepared according to the blending amounts in Table 11.

In Comparative Example 14, a sample was obtained by press molding in the same manner as in Example 26 using the styrene-butadiene rubber which is the rubber component used in Examples 26 to 28 and 31 to 33. Comparative Example 15 obtained a test piece in the same manner as in Example 28 except that it did not contain a surfactant and a polyhydric alcohol. Comparative Example 16 obtained a test piece in the same manner as in Example 28 except that it did not contain a polyhydric alcohol. In Comparative Example 17, the mixing step was carried out in the same manner as in Example 28 except that it did not contain a surfactant, but it did not wrap around the roll and no test piece was obtained. In Comparative Example 18, a sample was obtained by press molding in the same manner as in Example 29 using the silicone rubber which is the rubber component used in Examples 29 and 30. In Comparative Examples 19 and 20, each manufacturing process was carried out in the same manner as in Example 28 except that the blending amount of the polyhydric alcohol was changed. In Comparative Example 19, no test piece was obtained because the product was not wrapped around the roll, and Comparative Example 20 was obtained. Finally, I got a test piece.

(15) Evaluation Method The above evaluation test (3) was carried out on Examples 26 to 33 and Comparative Examples 14 to 16, 18 and 20 under the same conditions as in Example 1. In Examples 26 to 33 and Comparative Examples 14 to 16, 18 and 20, the fracture energy was calculated and evaluated from the results of the tensile test.

(16) Evaluation In Examples 26 to 28 and 31 to 33, the values of tensile strength (TS), 50% modulus (σ50), 100% modulus (σ100) and fracture energy were larger than those of Comparative Example 14. In Examples 29 and 30, the values of tensile strength (TS), 50% modulus (σ50), 100% modulus (σ100) and fracture energy were larger than those of Comparative Example 18. In Example 32, in which the amount of surfactant was larger than that in Example 28, the processability was lowered. In Example 33, in which the amount of polyhydric alcohol was higher than that in Example 28, the processability was lowered.

2 ... open roll, 10 ... first roll, 20 ... second roll, 30 ... rubber component, 34 ... bank, 36 ... intermediate mixture, 50 ... composite material, d ... roll spacing, V1, V2 ... rotation speed

Claims (9)

A step of mixing a cellulose nanofiber aqueous dispersion in which cellulose nanofibers are dispersed in an aqueous solvent, a cationic surfactant, and a polyhydric alcohol to obtain a CNF dispersion.
A drying step of removing an aqueous solvent from the CNF dispersion to obtain a fiber material, and a drying step.
A mixing step of mixing the fiber material with a rubber component to obtain a composite material,
Including
The mass ratio of the cationic surfactant to the cellulose nanofibers in the CNF dispersion is 0.1 to 2.0 times.
A method for producing a composite material, wherein the mass ratio of the polyvalent alcohol to the cellulose nanofibers in the CNF dispersion is 2.0 to 20.0 times. In claim 1,
A method for producing a composite material, wherein the cationic surfactant is one or more of a primary to tertiary amine salt and a quaternary ammonium salt. In claim 1,
The method for producing a composite material, wherein the cationic surfactant is a quaternary ammonium salt having a long-chain alkyl group having 10 to 18 carbon atoms. In any one of claims 1 to 3,
The method for producing a composite material, wherein the polyhydric alcohol is at least one of a dihydric alcohol and a trihydric alcohol. In any one of claims 1 to 4,
The mixing step is a method for producing a composite material, in which an open roll having a roll interval of more than 0 mm and 0.5 mm or less and a roll temperature of 0 ° C. to 50 ° C. is used for thinning. In any one of claims 1 to 5,
A method for producing a composite material, wherein the rubber component is nitrile rubber. In any one of claims 1 to 5,
A method for producing a composite material, wherein the rubber component is silicone rubber. In any one of claims 1 to 5,
A method for producing a composite material, wherein the rubber component is styrene-butadiene rubber. In any one of claims 1 to 8,
A composite material comprising a removal step of heating the composite material obtained in the mixing step in a heating furnace and degassing the inside of the heating furnace to remove polyvalent alcohol remaining in the composite material. Production method.

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