JP5394142B2 - Method for producing rubber composition - Google Patents

Description

  The present invention relates to a method for producing a rubber composition containing fibrillated fibers.

  Conventionally, in rubber compositions used for tires and the like, particulate fillers such as carbon black and silica are blended for reinforcement. Carbon black and silica have a high specific gravity of about 2. Therefore, in order to reduce the weight of the tire, it is required to reinforce the rubber composition with a reinforcing agent having a lower specific gravity.

  On the other hand, a technique for reinforcing a rubber composition with a fiber is known, and it is also known to blend fibrillated cellulose in order to enhance the reinforcing property. Such fibrillated cellulose has a specific gravity of about 1.3 and is smaller than that of carbon black or silica, so that weight reduction can be expected. However, fibrillated cellulose tends to be entangled and aggregated due to its flared form, and it is difficult to uniformly disperse it in the rubber composition. In addition, since cellulose has hydroxyl groups (OH) on the fiber surface, it is particularly easy to aggregate and is marketed as a water suspension for handling. Therefore, it is necessary to disperse the rubber composition in the rubber composition while removing water from the water suspension during the production of the rubber composition, and it is not easy to disperse uniformly. Therefore, the actual situation is that the reinforcing property by the fibrillated cellulose is not sufficiently exhibited.

  In Patent Document 1 below, fibrillated cellulose in water suspension is stirred and mixed in water together with latex rubber (so-called wet mixing), and the resulting master batch is used to make a conventional Banbury mixer, extruder, etc. And mixing with other chemicals (so-called dry mixing) to obtain the final rubber composition. However, this method requires equipment for wet mixing, has poor productivity, and further has a problem that the rubber polymer is limited to latex rubber.

  Patent Document 2 listed below discloses blending a rubber composition with a dry product obtained by combining fibrillated cellulose and mineral particles (particulate filler) such as carbon black or silica, Preparing a water suspension containing fibrillated fibers and particulate filler to obtain the dried product and drying it, and all or some of the water in the water suspension such as ethanol or methanol It is disclosed to replace with alcohol (paragraphs 0096-0098). However, this document requires a particulate filler to disperse the fibrillated cellulose in the polymer matrix, and does not disclose that the fibrillated cellulose is uniformly dispersed in the polymer without the particulate filler. . Further, this document obtains the dried product by combining a large amount of particulate filler together with fibrillated cellulose (see paragraph 0094). Thus, in the case where a large amount of particulate filler is essential, there is a problem that the effect of reducing the weight of the rubber composition by fibrillated cellulose cannot be obtained, and the hysteresis loss due to the particulate filler is large and the low heat build-up property is poor.

JP 2006-206864 A JP-T-2002-503621

  The present invention has been made in view of the above points, and provides a method for producing a rubber composition that can improve the balance between reinforcement and weight reduction and further improve the balance between low heat build-up. The purpose is to provide.

  The present inventors uniformly disperse the fibrillated cellulose in the diene rubber without adding particulate filler by immersing the fibrillated water-suspended cellulose in a specific organic solvent and drying it. The balance between reinforcement and weight reduction can be improved, and by using the dried fibrillated cellulose and a modified diene rubber having a functional group, the reinforcement is further improved and the balance with low heat generation is improved. As a result, the present invention was completed.

That is, in the method for producing a rubber composition according to the present invention, an aqueous suspension of fibrillated cellulose is immersed in an organic solvent composed of at least one kind of monohydric alcohol and ketone having a boiling point of 120 ° C. or lower, Dry to obtain a dried body of fibrillated cellulose containing 2 to 10% by weight of the organic solvent ,
The obtained dried cellulose is used as the amount of cellulose with respect to 100 parts by weight of a diene rubber containing 20 parts by weight or more of a modified diene rubber having a functional group capable of binding to a hydroxyl group on the fiber surface of the cellulose. 5 parts by weight or more is added and mixed.

  According to the present invention, by using fibrillated cellulose dipped in a specific organic solvent and dried, the dispersibility of the fibrillated cellulose in the rubber composition can be improved, and excellent reinforcing properties can be exhibited. The balance between reinforcement and weight reduction can be improved. Further, by using this dried fibrillated cellulose in combination with a modified diene rubber that can be bonded thereto, the balance between reinforcement and low heat build-up can be improved.

  Hereinafter, matters related to the implementation of the present invention will be described in detail.

  In the production method according to the present invention, an aqueous suspension of fibrillated cellulose is used. As the fibrillated cellulose, those pulverized and microfibrillated by a mechanical shearing force such as a high-pressure homogenizer can be used. Cellulose has a specific gravity of about 1.3 and is smaller than carbon black or silica having a specific gravity of about 2. Therefore, the weight of the rubber composition can be reduced by using this as a reinforcing agent.

  The water suspension is obtained by suspending or dispersing fibrillated cellulose in water, and water-suspended cellulose finely ground and fibrillated by mechanical shearing force in water can be used. . As such an aqueous suspension, for example, serisch PC-110A, PC-110B, PC-110S, PC-110T, FD-100F, FD-100G, KY-100G, KY-100S can be used as microfibrous cellulose. Etc. are commercially available (both manufactured by Daicel Chemical Industries, Ltd.), and these are preferably used. The form of these commercially available products is in the form of a cotton swab, and such a water suspension in the form of a cotton swab can be used.

  Although the diameter (namely, fiber diameter) of the fibrillated cellulose is not specifically limited, It is preferable that an average fiber diameter is 5 micrometers or less, More preferably, it is 0.01-1 micrometer. Further, the length of the fibrillated cellulose (that is, fiber length) is not particularly limited, but the average fiber length is preferably 10 to 1500 μm. Here, the average fiber diameter is measured by observation with a scanning electron microscope (SEM). Specifically, 20 fibrillated fibers are randomly extracted from image data obtained by microscopic observation, the minor axis is measured, and the arithmetic average is defined as the average fiber diameter. The average fiber length is measured according to JIS P8121 using a fiber length measuring machine (FS-200) manufactured by KAJANI.

  The ratio of the fibrillated cellulose contained in the water suspension is not particularly limited. For example, an aqueous suspension having a fiber ratio of 5 to 95% by weight and a water ratio of 95 to 5% by weight can be used. It may contain a small amount of a third component such as a stabilizer or impurities as long as the effect is not impaired.

  In the production method according to the present invention, the water suspension is immersed in a specific organic solvent, and then dried to produce a dried fibrillated cellulose.

  As the organic solvent, at least one kind of monohydric alcohol and ketone having a boiling point of 120 ° C. or lower is used. Specifically, methanol (boiling point 64.7 ° C), ethanol (boiling point 78.4 ° C), 1-propanol (boiling point 97.2 ° C), 2-propanol (boiling point 82.4 ° C), 1-butanol (boiling point) 117 ° C.), 2-butanol (boiling point 99.5 ° C.), monobutyl alcohol such as isobutyl alcohol (boiling point 108 ° C.), t-butyl alcohol (boiling point 82.4 ° C.), acetone (boiling point 56.5 ° C.), methyl ethyl ketone And ketones such as (boiling point 79.5 ° C.).

  By using such a specific hydrophilic organic solvent, when the water suspension is immersed, the water taken into the fibrillated cellulose is replaced with the organic solvent, and the water can be removed. The reason for this is not clear, but it is presumed that the surface of the fibrillated cellulose is more easily bonded to the hydrophilic organic solvent than water due to the electronegativity. From such a viewpoint, the organic solvent is preferably selected from monohydric alcohols and ketones having 4 or less carbon atoms, and more preferably 3 or less carbon atoms.

  Further, by using a volatile solvent having a boiling point of 120 ° C. or lower as the organic solvent, it can be easily evaporated in the drying step after immersion and the kneading step with the diene rubber. From such a viewpoint, the boiling point is preferably 100 ° C. or less, more preferably 55 to 85 ° C.

  When immersing the water suspension in an organic solvent, it is preferable to immerse the water suspension in an organic solvent in an amount of 5 to 15 times the weight of water contained in the water suspension. When the ratio of organic solvent / water is less than 5 times, sufficient dehydration effect cannot be obtained even if the water suspension is immersed in the organic solvent. Moreover, since this dehydration effect reaches its peak at about 10 to 15 times, it is preferable to make it 15 times or less from the viewpoint of cost.

  By soaking the aqueous suspension in the organic solvent in this way, the fibrillated cellulose becomes a suspension in the organic solvent. Preferably, after immersion, filtration is performed to remove excess organic solvent, whereby a suspension of fibrillated cellulose in a wet state wetted with the organic solvent is obtained. During this filtration, the water initially contained is removed along with the excess organic solvent.

  The drying method of the suspension containing the fibrillated cellulose is not particularly limited as long as the organic solvent can be removed from the suspension, and can be performed using, for example, an oven. By removing the organic solvent by drying, slippage due to the presence of the organic solvent during kneading with the diene rubber can be prevented, and kneading workability can be improved. However, drying should be performed to such an extent that the organic solvent contained is not completely removed. This is because the fibrillated cellulose aggregates and solidifies when the organic solvent is completely removed. Therefore, the dried product obtained by drying preferably contains about 2 to 10% by weight of an organic solvent, more preferably 3 to 5% by weight of an organic solvent.

  The dried fibrillated cellulose thus obtained contains fibrillated cellulose as a main component (for example, 80% by weight or more), and particulate fillers such as carbon black and silica are substantially free. It is preferably not included. That is, it is preferable to immerse in a water suspension of fibrillated cellulose in an organic solvent without substantially containing a particulate filler and then dry it. According to the present invention, fibrillated cellulose can be uniformly dispersed in a rubber composition without containing a particulate filler, and the balance between reinforcement and weight reduction can be improved. Therefore, it becomes possible to make the rubber composition finally obtained into an embodiment in which no particulate filler is contained. Particulate fillers such as carbon black and silica cause the energy loss due to the aggregation of the particles even with relatively small strain deformation of the vulcanized rubber, which increases the loss tangent tanδ and deteriorates the low heat generation. On the other hand, fibrillated cellulose is less likely to be entangled by fibrillation, or if it can be dispersed uniformly, tan δ is smaller than that when a particulate filler is used, and it is difficult to generate heat. Therefore, by enabling an embodiment that does not include particulate filler, an increase in hysteresis loss due to the particulate filler can be suppressed, and low heat build-up can be improved. From such a viewpoint, it is preferable that the dry body does not contain any particulate filler. However, the dry body may contain a small amount of particulate filler as long as the effect is not impaired. You may contain about 10 weight% or less.

  The dried product obtained above is then added to a diene rubber and kneaded to produce a rubber composition. For kneading at that time, a Banbury mixer, a roll, a kneader or the like generally used in the preparation of the rubber composition can be used.

  As the diene rubber which is a rubber component, a modified diene rubber having a functional group capable of binding to a hydroxyl group on the surface of cellulose fiber is used. With such a modified diene rubber, the dispersibility of the fibrillated cellulose can be further improved by bonding the functional group to the hydroxyl group on the fiber surface of the fibrillated cellulose, and the reinforcing property and low heat build-up can be improved. The balance can be further improved.

  The bond includes not only a narrow chemical bond such as a covalent bond but also a broad chemical bond such as a hydrogen bond. Examples of such functional groups include amino groups, epoxy groups, hydroxyl groups, alkylsilyl groups, alkoxysilyl groups, and carboxyl groups. The amino group may be not only a primary amino group but also a secondary amino group. The alkylsilyl group may be a monoalkylsilyl group, a dialkylsilyl group, or a trialkylsilyl group. The alkoxysilyl group refers to a group in which at least one of the three hydrogens of the silyl group is substituted with an alkoxyl group, and includes a trialkoxysilyl group, an alkyldialkoxysilyl group, and a dialkylalkoxysilyl group.

  The polymer type of the modified diene rubber is not particularly limited, but styrene butadiene rubber (SBR), butadiene rubber (BR), natural rubber (NR), isoprene rubber (IR), styrene-isoprene copolymer rubber, butadiene. -Isoprene copolymer rubber etc. are mentioned, More preferably, it is SBR and BR.

  As the modified diene rubber, a terminal-modified polymer obtained by introducing the above functional group by modifying a polymer terminal of a polymer synthesized by anionic polymerization with various modifiers can be used. Such a polymer polymerization method and terminal modification method can be performed by a conventionally known method, for example, by the methods described in JP-A Nos. 2002-284930 and 2002-284933.

  The modified diene rubber is used in an amount of 20 parts by weight or more based on 100 parts by weight of the total diene rubber blended in the rubber composition. When the content of the modified diene rubber is less than 20 parts by weight, the bonding with the fibrillated cellulose becomes insufficient, and the effect of improving the reinforcing property and low heat build-up cannot be obtained sufficiently. The diene rubber compounded in the rubber composition may be a modified diene rubber alone (ie, 100 parts by weight) or a blend with another unmodified diene rubber. Preferably, the diene rubber as a rubber component is composed of 20 to 70 parts by weight of a modified diene rubber and 80 to 30 parts by weight of an unmodified diene rubber. Examples of the other diene rubber include, but are not limited to, natural rubber, isoprene rubber, styrene-butadiene rubber, butadiene rubber, styrene-isoprene copolymer rubber, butadiene-isoprene copolymer rubber, and the like. These can be used alone or in combination of two or more.

  The dry weight of the fibrillated cellulose may be appropriately set so as to exhibit the reinforcing properties required depending on the use of the rubber composition, but as the amount of cellulose relative to 100 parts by weight of the diene rubber ( That is, it is preferably 5 parts by weight or more (as the addition amount of only fibrillated cellulose excluding other components such as an organic solvent). This is because if the amount is less than 5 parts by weight, it is difficult to obtain a sufficient reinforcing effect. Although the upper limit of this compounding quantity is not specifically limited, Usually, it is 200 weight part or less, and it is more preferable that it is 100 weight part or less.

  The rubber composition may contain various additives generally used in the rubber industry, such as softeners, plasticizers, anti-aging agents, zinc white, stearic acid, resins, vulcanizing agents, and vulcanization accelerators. it can. These additives may be added to the diene rubber together with the dried product, or may be added in a step different from the dried product, and the order of addition is not particularly limited. Usually, in the first mixing stage, a chemical excluding vulcanizing additives such as a vulcanizing agent and a vulcanization accelerator is added to the diene rubber together with the dried body and kneaded, and then the second mixing stage. Thus, the rubber composition can be produced by adding and mixing the vulcanizing additive to the kneaded product obtained in the first mixing stage. In addition, since particulate fillers such as carbon black and silica tend to deteriorate in weight and low heat build-up, it is preferable not to add as much as possible, but it is added within a range not impairing the effect of the present invention. It doesn't matter.

  The rubber composition according to the present invention is used as rubber members of pneumatic tires such as bead fillers and sidewall rubbers by vulcanization molding according to a conventional method, or for various rubber products such as vibration-proof rubbers and belts. be able to. The rubber composition of the present invention is particularly suitable for use as a rubber member for pneumatic tires because of its excellent balance between weight reduction, reinforcement and low heat build-up as described above, and the reinforcement required for tires. And the balance of fuel efficiency can be improved.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

[Production Example 1]
As an aqueous suspension of fibrillated cellulose, “Cerish PC-110S” manufactured by Daicel Chemical Industries, Ltd. (average fiber diameter = 1 μm, average fiber length = 600 μm, microfibrous cellulose = 35 wt%, water = 65 % By weight) was used. 100 parts by weight of the aqueous suspension was immersed in 650 parts by weight of ethanol (10 times the amount of water contained in the aqueous suspension), stirred gently, and then filtered to remove excess ethanol. The obtained wet body of fibrillated cellulose was dried in an oven at 120 ° C. for 120 minutes to obtain a dried body of fibrillated cellulose. The obtained dried product was in a soft cotton-like form without being coagulated and solidified. When the volatile matter (ethanol content) of this dried product was examined, it was 5% by weight.

[Production Example 2]
A dried fibrillated cellulose was obtained in the same manner as in Production Example 1 except that acetone was used in an amount of 325 parts by weight (5 times the amount of water contained in the water suspension) instead of ethanol. The obtained dried product was in a soft cotton-like form without being coagulated and solidified, and the volatile content (acetone content) was 3% by weight.

[Production Example 3]
A dried fibrillated cellulose was obtained in the same manner as in Production Example 1, except that methanol was replaced with 325 parts by weight (5 times the amount of water contained in the water suspension). The obtained dried product is in a soft cotton-like form without being agglomerated and solidified, and can be uniformly dispersed in the rubber polymer. The volatile matter (methanol content) of the dried product was 4% by weight.

[Production Example 4]
As an aqueous suspension of fibrillated cellulose, “Cerish KY-100G” manufactured by Daicel Chemical Industries, Ltd. (average fiber diameter = 0.1 μm, average fiber length = 500 μm, fine fibrous cellulose = 10% by weight, water = 90% by weight). 100 parts by weight of the aqueous suspension was immersed in 630 parts by weight of ethanol (7 times the amount of water contained in the aqueous suspension), stirred gently, and then filtered to remove excess ethanol. The obtained wet body of fibrillated cellulose was dried in an oven at 120 ° C. for 120 minutes to obtain a dried body of fibrillated cellulose. The obtained dried product was in a soft cotton-like form without being coagulated and solidified. The volatile matter (ethanol content) of the dried product was examined and found to be 3% by weight.

[Production Example 5]
A dried fibrillated cellulose was obtained in the same manner as in Production Example 4, except that acetone was used in an amount of 630 parts by weight (7 times the amount of water contained in the water suspension) instead of ethanol. The obtained dried product was in a soft cotton-like form without being coagulated and solidified, and the volatile content (acetone content) was 3% by weight.

[Production Example 6]
A dried fibrillated cellulose was obtained in the same manner as in Production Example 4 except that methanol was changed to 630 parts by weight (7 times the amount of water contained in the water suspension) instead of ethanol. The obtained dried product is in a soft cotton-like form without being agglomerated and solidified, and can be uniformly dispersed in the rubber polymer. The volatile matter (methanol content) of the dried product was 4% by weight.

[Test Example 1]
Using a Banbury mixer, a rubber composition was prepared according to the formulation shown in Table 1 below. Specifically, a reinforcing agent, stearic acid, and zinc oxide are added to the diene rubber, kneaded to obtain a first mixture (discharge temperature: 150 ° C.), and then in the second mixing step, the first mixture A vulcanization accelerator and sulfur were added and kneaded to obtain a rubber composition (discharge temperature: 110 ° C.). As the reinforcing agent, Examples 1, 2 and Comparative Examples 1, 2 use the dried product of Production Example 1, Examples 3 and 4 use the dried product of Production Example 2, and Comparative Examples 3 and 4 use Daicel. Chemical Industry Co., Ltd. “Serish PC-110S” was used as it was, and in Comparative Example 5, carbon black was used. In Examples 1-4 and Comparative Examples 1-4, it added so that the compounding quantity of solid content (namely, fibrillated cellulose) might become the quantity of Table 1. Each component in Table 1 is as follows.

NR: Natural rubber, RSS No. 3 Unmodified BR: Unmodified butadiene rubber, “Diene NF35R” manufactured by Asahi Kasei Corporation
Modified BR: modified polybutadiene rubber having a hydroxyl group as a functional group synthesized by anionic polymerization, “Toughden E40” manufactured by Asahi Kasei Corporation
・ Carbon black: “Seast V” manufactured by Tokai Carbon Co., Ltd.
・ Stearic acid: "Industrial stearic acid" manufactured by Kao Corporation
・ Zinc oxide: “No. 1 Zinc Hana” manufactured by Mitsui Mining & Smelting Co., Ltd.
-Vulcanization accelerator: N-tert-butyl-2-benzothiazolesulfenamide-Sulfur: "5% oil-treated powdered sulfur" manufactured by Tsurumi Chemical Co., Ltd.

  Each rubber composition obtained was vulcanized at 160 ° C. for 20 minutes to prepare a test piece having a predetermined shape, and M300 (300% modulus), specific gravity and tan δ were measured using the obtained test piece. evaluated. Each evaluation method is as follows.

M300: The tensile stress at 300% elongation was measured by a tensile test according to JIS K6251 and displayed as an index with the value of Comparative Example 1 being 100. It shows that M300 is so large that an index | exponent is large and it is excellent in reinforcement.

Specific gravity: In accordance with JIS K6268, the measured specific gravity was displayed as an index with the value of Comparative Example 1 as 100. The smaller the index, the smaller the specific gravity, and thus the lighter the weight.

Tan δ: According to JIS K6394, the loss coefficient tan δ was measured under the conditions of a temperature of 70 ° C., a frequency of 10 Hz, a static strain of 10%, and a dynamic strain of 2%, and displayed as an index with the value of Comparative Example 1 being 100. The smaller the index, the smaller the tan δ, and the less the heat is generated.

  The results are as shown in Table 1. Compared to Comparative Example 4 in which fibrillated water-suspended cellulose was blended as it was, and Comparative Example 5 in which carbon black was used as a reinforcing agent, the dried product of Production Example 1 In Comparative Example 1 in which M300 was used, M300 was high and the reinforcing property was excellent, the balance between weight reduction and the reinforcing property was improved, tan δ was low, and the low heat generation property was also excellent. Compared to Comparative Example 1, in Examples 1 to 4, in which a modified polymer is used in combination with a diene rubber, M300 is further improved, tan δ is low, and the balance between reinforcement and low heat generation is further improved. It was.

  In Comparative Example 2, since the amount of the modified polymer was small, the amount of improvement in reinforcement and low heat build-up was less than that in Comparative Example 1. In Comparative Example 3, although the modified polymer was used for the diene rubber, the water-suspended fibrillated cellulose was used as it was, so that both the reinforcing property and the low heat generation were insufficient.

[Test Example 2]
According to the composition shown in Table 2 below, a rubber composition was prepared in the same manner as in Test Example 1 above. About each obtained rubber composition, M300, specific gravity, and tan-delta were measured and evaluated using the vulcanized test piece similarly to Test Example 1. However, all evaluations were expressed as an index with the value of Comparative Example 6 as 100. The results are as shown in Table 2. Even when the amount of the reinforcing agent was 15 parts by weight, the same tendency as in Test Example 1 was obtained.

[Test Example 3]
In accordance with the formulation shown in Table 3 below, as a reinforcing agent, the dried product of Production Example 4 was used in Examples 7 and 8 and Comparative Examples 10 and 11, and the dried product of Production Example 5 was used in Examples 9 and 10. In Comparative Examples 12 and 13, a rubber composition was prepared in the same manner as in Test Example 1 except that “Cerish KY-110G” manufactured by Daicel Chemical Industries, Ltd. was used as it was, and carbon black was used in Comparative Example 14. . Each component in Table 3 is the same as Table 1 except for the following.

Unmodified SBR: Unmodified styrene butadiene rubber, “VSL5025-2HM” manufactured by LANXESS
Modified SBR: Modified styrene butadiene rubber having a carboxyl group as a functional group synthesized by anionic polymerization, “PBR4003” manufactured by LANXESS.

  About each obtained rubber composition, M300, specific gravity, and tan-delta were measured and evaluated about the vulcanized test piece similarly to Test Example 1. However, all evaluations were expressed as an index with the value of Comparative Example 10 as 100.

  The results are as shown in Table 3. Compared to Comparative Example 13 in which fibrillated water-suspended cellulose was blended as it was, and Comparative Example 14 using carbon black as a reinforcing agent, the dried product of Production Example 4 In Comparative Example 10 in which M300 was used, M300 was high and the reinforcing property was excellent, the balance between weight reduction and the reinforcing property was improved, tan δ was low, and the low heat generation property was also excellent. Compared to Comparative Example 10, when Examples 7 to 10 were used in combination with a modified polymer, M300 was further improved, tan δ was low, and the balance between reinforcement and low heat generation was further improved.

  According to the present invention, it is possible to produce a rubber composition that improves the balance between weight reduction, reinforcement, and low heat build-up without deteriorating productivity with conventional equipment such as a Banbury mixer or roll. It can be used for various applications such as tire rubber members, anti-vibration rubber and belts.

Claims (5)

A water suspension of fibrillated cellulose is immersed in an organic solvent composed of at least one kind of monohydric alcohol and ketone having a boiling point of 120 ° C. or less, and then dried, and 2-10 wt% of the organic solvent is added. Obtaining a dried body of fibrillated cellulose containing , and
The obtained dried cellulose is used as the amount of cellulose with respect to 100 parts by weight of a diene rubber containing 20 parts by weight or more of a modified diene rubber having a functional group capable of binding to a hydroxyl group on the fiber surface of the cellulose. Adding and mixing 5 parts by weight or more,
The manufacturing method of the rubber composition containing this. 2. The method for producing a rubber composition according to claim 1, wherein the dried product of cellulose does not contain a particulate filler or contains 10% by weight or less .   The method for producing a rubber composition according to claim 1 or 2, wherein the water suspension is immersed in the organic solvent in an amount of 5 to 15 times the weight of water contained in the water suspension. The drying is performed without agglomerating and solidifying the fibrillated cellulose to obtain the dried product in a cotton-like form, and the obtained cotton-like dried product is added to the diene rubber and mixed. The manufacturing method of the rubber composition of any one of Claims 1-3 characterized by the above-mentioned.   The rubber composition according to any one of claims 1 to 4, wherein the functional group is at least one selected from an amino group, an epoxy group, a hydroxyl group, an alkylsilyl group, an alkoxysilyl group, and a carboxyl group. Manufacturing method.