JP4657099B2 - Reinforcing composite and pneumatic tire using the same - Google Patents

Description

  The present invention relates to a reinforcing composite used particularly for a carcass of a pneumatic tire, which has a high ratio of resources outside oil and a good strength, and a pneumatic tire using the same. .

  Currently commonly used tires include materials derived from petroleum resources such as synthetic rubber, synthetic fibers, petroleum-based fillers, petroleum-based softeners, etc., but in preparation for the future depletion of petroleum resources, raw materials for tires Is also required for effective use of non-oil resources. For example, Patent Document 1 describes a tire that is friendly to the earth and is prepared for a future reduction in the supply of oil by replacing some or all of the raw materials made of petroleum resources used in tires with raw materials made of non-oil resources. Further, 75% by weight or more of the total weight is composed of raw materials made of resources other than petroleum, and tires containing natural rubber have been proposed as raw materials made of resources other than petroleum. In Patent Document 1, inorganic fillers and / or biofillers are used instead of carbon black, vegetable oils and fats are used instead of petroleum-based oils, and natural fibers are used instead of synthetic fibers. As natural fibers, rayon, Acetate, cupra and the like have been proposed.

On the other hand, for example, in the reinforcing composite of ply cord and rubber used for carcass and the like, it is desired to improve the ratio of non-oil resources. In the reinforcing composite, the physical properties of the ply cord and the rubber layer are respectively increased. In addition to strength and durability, it is essential to ensure initial or long-term adhesion between the ply cord and the rubber layer. Conventionally, rayon, lyocell, etc. have been proposed as ply cords using non-oil resources. Since these have properties of relatively high elastic modulus, good bending fatigue resistance, and relatively light weight, their use as an alternative to, for example, steel cords has been studied. However, when rayon is used as a ply cord, due to the characteristics of rayon that easily absorbs moisture, especially when the rubber in contact with the ply cord contains silica as a filler, the ply cord and the rubber part are affected by moisture. There is a problem that the adhesive strength is reduced or the strength of the ply cord itself is reduced. Although lyocell is superior in swelling resistance compared to rayon, it is not easy to obtain sufficient adhesion between the ply cord and the rubber part, especially when the ratio of non-oil resources in the rubber part is increased. In fact, a reinforcing composite that has an external resource ratio and can maintain sufficient durability has not yet been obtained.
JP 2003-63206 A

  The present invention solves the above-mentioned problems, a composite for reinforcement in which the ratio of resources outside oil is high, and the adhesive strength between the ply cord and the rubber part is well maintained for a long period of time and a pneumatic tire using the same for a carcass For the purpose of provision.

  The present invention relates to a reinforcing composite comprising a ply cord made of purified cellulose fibers and a rubber layer, and used as a carcass layer or a belt layer of a pneumatic tire, wherein the rubber layer is a rubber component and silica as a filler. The rubber component contains at least natural rubber, the silica content is in the range of 20 to 60 parts by mass with respect to 100 parts by mass of the rubber component, and the above ply The reinforcing composite in which the adhesive strength between the cord and the rubber layer in the standard state at a temperature of 20 ° C. and a relative humidity of 65% is 85% or more of the adhesive strength at a temperature of 120 ° C. and an absolutely dry state. About the body.

  The present invention also relates to a reinforcing composite in which the rubber component contains an epoxidized natural rubber.

  The present invention also provides that the rubber composition contains at least a rubber component composed of 50 to 90% by mass of natural rubber and 10 to 50% by mass of epoxidized natural rubber, and a filler. The present invention relates to a reinforcing composite in which the proportion of silica is in the range of 85 to 100% by mass.

  The present invention also relates to a reinforcing composite in which the rubber composition contains a silane coupling agent.

The present invention also relates to a pneumatic tire using the above reinforcing composite for a carcass.
The present invention also relates to a pneumatic tire using the above reinforcing composite for a jointless belt layer.

  According to the present invention, since the initial and long-term adhesion between the ply cord and the rubber layer can be improved while improving the ratio of non-oil resources of the reinforcing composite, the non-oil resources can be used at a high ratio. A reinforcing composite having excellent long-term strength retention and excellent durability can be obtained. Further, the use of the reinforcing composite for a carcass layer and / or a belt layer has a high ratio of non-oil resources and excellent durability. A pneumatic tire can be obtained.

  The reinforcing composite of the present invention contains at least a ply cord made of purified cellulose fiber, a rubber component and a rubber layer containing silica, and the rubber component contains at least natural rubber. In the reinforcing composite of the present invention, the ply cord is composed of purified cellulose fibers that are natural fibers, and the rubber component contains natural rubber, so that resources other than petroleum are used for both the ply cord and the rubber portion. Reinforcing composites with a high ratio of non-oil resources are formed.

  In the present invention, the purified cellulose fiber means a cellulose fiber obtained by spinning raw cellulose directly after dissolving it in an organic solvent, for example, and is made into fiber without passing through a cellulose derivative. Examples thereof include lyocell obtained by a solvent spinning method. That is, the purified cellulose fiber used in the present invention does not undergo derivatization by chemical decomposition of raw cellulose as in the production of rayon, cupra, etc., so that the purified cellulose fiber retains the crystal structure of raw cellulose. In addition, there is little decrease in molecular weight when compared with raw material cellulose, high crystallinity and orientation, and excellent physical strength. In addition, the purified cellulose fiber is superior in swelling resistance when wet compared to regenerated fiber such as rayon due to its high crystallinity and orientation.

  The purified cellulose fiber used in the present invention can be formed as a long fiber filament by, for example, continuous spinning after dissolving raw material cellulose in an organic solvent such as amine oxide.

  The rubber composition constituting the rubber layer in the reinforcing composite of the present invention contains natural rubber derived from resources other than petroleum as a rubber component. The content of the natural rubber in the rubber component is preferably in the range of 70 to 100% by mass. When the content is 70% by mass or more, a sufficient amount of natural rubber is blended in the rubber component, and the effect of improving the non-petroleum resource ratio by replacing synthetic rubber with natural rubber is good. The content is preferably 80% by mass or more, and more preferably 100% by mass.

  The rubber component used in the present invention includes, in addition to natural rubber, for example, ethylene propylene-diene terpolymer (EPDM), styrene butadiene rubber (SBR), butadiene rubber, isoprene rubber, butyl rubber, halogenated butyl rubber, acrylonitrile. -Synthetic rubber such as butadiene rubber (NBR) may be used singly or in combination of two or more, but the rubber component is composed of natural rubber and its derivatives in that the effect of improving the non-petroleum resource ratio is obtained satisfactorily. It is preferable. Examples of natural rubber derivatives include epoxidized natural rubber. Epoxidized natural rubber is preferable in that it has a large polarity and can effectively impart an effect of improving the adhesion between the ply cord and the rubber layer.

  When epoxidized natural rubber is used, the content of epoxidized natural rubber in the rubber component is preferably in the range of 10 to 50% by mass. When the content is 10% by mass or more, the effect of improving the adhesiveness between the ply cord and the rubber layer can be obtained satisfactorily. When the content is 50% by mass or less, the reinforcing composite is combined with other rubber components. The various performances required as can be appropriately controlled according to the purpose, and good mechanical strength can be imparted. The content is more preferably 15% by mass or more, and more preferably 40% by mass or less. Further, in the present invention, the rubber component is particularly preferably composed of natural rubber and epoxidized natural rubber.

  The rubber composition constituting the rubber layer in the reinforcing composite of the present invention contains silica as a filler. Silica is excellent in the reinforcing effect of the rubber composition, but has the property of easily adsorbing moisture. Therefore, in the reinforcing composite in which the rubber composition containing silica and the ply cord having poor swelling resistance to water are combined. In addition, there is a tendency that the strength of the ply cord is easily lowered with long-term use. In the present invention, a refined cellulose fiber having excellent resistance to swelling with water and a rubber composition containing silica are used in combination, thereby improving the resource ratio outside petroleum and increasing the moisture content during use. Thus, a reinforcing composite having excellent long-term strength retention can be obtained. Thereby, the pneumatic tire which is excellent in durability can be manufactured without requiring advanced humidity management in the manufacturing process.

  The content of silica in the rubber layer of the reinforcing composite of the present invention is in the range of 20 to 60 parts by mass with respect to 100 parts by mass of the rubber component. If the blending amount is 20 parts by mass or more, the reinforcing effect on the rubber composition is good, and if it is 60 parts by mass or less, the adhesion with the ply cord due to the rubber composition becoming too hard or the durability is lowered. Can be prevented. The content is more preferably 30 parts by mass or more and more preferably 55 parts by mass or less with respect to 100 parts by mass of the rubber component.

  In the present invention, the filler contained in the rubber composition constituting the rubber layer may be only silica, but as fillers other than silica, for example, carbon black, titanium oxide, magnesium oxide, calcium carbonate, carbonic acid Magnesium, aluminum hydroxide, magnesium hydroxide, calcium sulfate, talc, clay, mica and the like may be contained. The composition of the filler can be appropriately controlled according to the performance required for the reinforcing composite. In the present invention, the composition of the filler is preferably adjusted so that the proportion of silica in the entire filler is 85 to 100% by mass. When the ratio of silica in the whole filler is 85% by mass or more, the ratio of non-oil resources in the reinforcing composite is improved by reducing the amount of fillers derived from petroleum resources such as carbon black. preferable. The ratio is more preferably 85% by mass or more, and further preferably 90% by mass or more.

Preferred silica used in the present invention includes silica having a nitrogen adsorption specific surface area in the range of 70 to 150 m ² / g. When the nitrogen adsorption specific surface area of silica is 70 m ² / g or more, the reinforcing effect of the rubber composition by blending silica is good, and when it is 150 m ² / g or less, the Mooney viscosity of the rubber composition is excessively increased. , And the risk of impairing the workability when producing a composite of the rubber composition and the ply cord is low. The nitrogen adsorption specific surface area of silica is particularly preferably 80 m ² / g or more, more preferably 90 m ² / g or more, and preferably 130 m ² / g or less. In addition, the nitrogen adsorption specific surface area of a silica can be measured by the method based on ASTM-D-4820-93.

Examples of the silica to be blended in the present invention include, for example, a dry process silica manufactured by a combustion method and an arc method, and a wet process silica manufactured by a precipitation method and a gel method, but a rubber layer and a ply cord. From the standpoint of good adhesion, those having a large number of silanol groups on the silica surface are preferably used. Silica may be used alone or in combination of two or more. When two or more types of silica are used in combination, the average nitrogen adsorption specific surface area may be in the range of 70 m ² / g or more and 150 m ² / g.

  In the rubber layer of the reinforcing composite of the present invention, the rubber component consists of 50 to 90% by mass of natural rubber and 10 to 50% by mass of epoxidized natural rubber, and the silica content in the filler is 85 to 100%. It is particularly preferable that the rubber composition is formed of a rubber composition in which the silica is blended in the range of 20 to 60 parts by mass with respect to 100 parts by mass of the rubber component.

  The rubber composition used in the present invention preferably further contains a silane coupling agent. When silica is compounded in the production of rubber products, a silane coupling agent is usually used for the purpose of further improving the reinforcing effect of the silica, but the silane coupling agent compounded in the present invention is When used in combination with purified cellulose fibers, it acts not only on rubber components and silica but also on purified cellulose fibers. That is, when a silane coupling agent is present in the rubber composition used in the present invention, the adhesion between the ply cord and the rubber layer is further enhanced by the action of the silane coupling agent on the hydroxyl group in the purified cellulose fiber. It is possible to form a reinforcing composite that is improved and has excellent durability.

  It is preferable that the compounding quantity of a silane coupling agent shall be in the range of 4-12 mass% of the compounding quantity of a silica. When the blending amount of the silane coupling agent is 4% by mass or more of the blending amount of silica, the reinforcing effect on the rubber composition is obtained well and the effect of improving the adhesion between the ply cord and the rubber layer is also good. When the compounding amount of the silane coupling agent is 12% by mass or less of the compounding amount of silica, the effect as a softening agent of the silane coupling agent is satisfactorily exhibited. The compounding amount of the silane coupling agent is more preferably 6% by mass or more, and more preferably 10% by mass or less of the compounding amount of silica.

  As the silane coupling agent, for example, those having a thiol-based, amine-based or halogen-based functional group can be preferably used alone or in combination of two or more. Specifically, bis (3-triethoxy Silylpropyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylpropyl) tetrasulfide, bis (triethoxylylethyltolylene) polysulfide, 3-mercaptopropyltriethoxysilane, 2 -Mercaptoethyltrimethoxysilane and the like.

  With respect to the adhesive strength between the ply cord and the rubber layer of the reinforcing composite of the present invention, the adhesive strength in a standard state at a temperature of 20 ° C. and a relative humidity of 65% is 85 ° C. in an absolutely dry state at a temperature of 120 ° C. % Or more. When the adhesive strength in the standard state is 85% or more of the adhesive strength in the absolutely dry state, the strength reduction due to the humidity of the reinforcing composite is small, and the durability when using the tire is good. The relationship between the adhesive strength between the ply cord and the rubber layer in the standard state and the absolutely dry state is evaluated by performing a peel test under the same conditions except for temperature and humidity using an Instron, for example. be able to.

  In addition, for example, the following blending components can be appropriately blended in the rubber composition used in the present invention.

  As the vulcanizing agent, for example, a sulfur-based vulcanizing agent is preferably used, and can be blended within a range of, for example, 3 to 8 parts by mass with respect to 100 parts by mass of the rubber component. As a sulfur type vulcanizing agent, 1 type (s) or 2 or more types can be used among sulfur, a morpholine disulfide, etc., for example.

  Vulcanization accelerators include sulfenamide, thiazole, thiuram, thiourea, guanidine, dithiocarbamic acid, aldehyde-amine, aldehyde-ammonia, imidazoline, or xanthate vulcanization accelerators. Of these, one or more can be blended.

  As an anti-aging agent, 1 type (s) or 2 or more types can be mix | blended among amine type, a phenol type, an imidazole type, a carbamic acid metal salt, a wax, etc., for example.

  Softeners include process oil, lubricating oil, paraffin, liquid paraffin, petroleum asphalt, petroleum softener such as petrolatum, fatty oil softener such as castor oil, linseed oil, rapeseed oil, coconut oil, beeswax, carnauba wax In addition to waxes such as lanolin, tall oil, sub, linoleic acid, palmitic acid, stearic acid, lauric acid and the like can be blended.

  Examples of plasticizers include DMP (dimethyl phthalate), DEP (diethyl phthalate), DBP (dibutyl phthalate), DHP (diheptyl phthalate), DOP (dioctyl phthalate), DINP (diisononyl phthalate), DIDP. (Diisodecyl phthalate), BBP (butyl benzyl phthalate), DLP (dilauryl phthalate), DCHP (dicyclohexyl phthalate) and the like may be blended.

  Furthermore, as a scorch inhibitor for preventing or delaying scorch, for example, organic acids such as phthalic anhydride, salicylic acid and benzoic acid, nitroso compounds such as N-nitrosodiphenylamine, N-cyclohexylthiophthalimide and the like can be blended. .

  FIG. 1 is a diagram illustrating an example of a reinforcing composite body according to the present invention. The reinforcing composite of the present invention is produced, for example, by the following method. First, a ply cord 14 made of purified cellulose fibers is used as a warp, and about 8 to 13 pieces / 10 cm are driven to produce a weave fabric 13 made of the warp and weft 15, and the drape fabric 13 is immersed in an adhesive such as RFL. Thereafter, the warp yarn is baked with a predetermined tension. This is cut into a predetermined length, and an unvulcanized product of the rubber composition according to the present invention is topped on top and bottom of the interwoven fabric to form a rubber layer 12, and a reinforcing composite 11 including the rubber layer 12 and the ply cord 14; To do. The reinforcing composite 11 is applied to a portion that becomes a carcass layer and / or a belt layer in the production of a pneumatic tire, and then becomes a carcass layer and / or a belt layer through a vulcanization process.

  The reinforcing composite of the present invention is used as a carcass layer and / or a belt layer of a pneumatic tire. It is also preferably used as a jointless belt layer. FIG. 2 is a diagram showing a right half of a sectional view of the pneumatic tire according to the present invention. The carcass ply 21 made of the reinforcing composite of the present invention is arranged as one ply that is folded and locked around the bead core 25 of the bead portion 24 from the tread portion 22 through the sidewall portion 23. A belt layer 26 composed of two belt plies is disposed at an angle of 5 ° to 45 ° in the tire circumferential direction at the crown portion of the tire. FIG. 2 shows a pneumatic tire having a radial structure, and the warp yarns of the carcass ply are arranged so as to extend radially (perpendicular to the tire circumferential direction) in the radial direction inside the tire. The pneumatic tire T is manufactured by using the above carcass ply and belt ply, combining a bead core, tread rubber, etc. by a normal molding method to form a raw tire cover, and vulcanizing it with a vulcanization mold. obtain.

[Example]
EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.

<Production of rubber sheet>
Among the ingredients shown in Table 1, the components excluding sulfur and vulcanization accelerator were kneaded for 4 minutes or more using 1.7 L Banbury, discharged at 145 ° C., and then added with sulfur and vulcanization accelerator. It knead | mixed for 2 minutes or more at 100 degreeC, and it shape | molded by the method of sheeting using a roll, and produced the sheet | seat of thickness 0.7mm which consists of rubber composition AC.

Note 1: The epoxidized natural rubber is “ENR25” (epoxidation rate: 25%) manufactured by Kungpu Langley.
Note 2: Silica is “Ultrasil VN3” manufactured by Degussa.
Note 3: The silane coupling agent is “Si75” manufactured by Degussa.
Note 4: Stearic acid is “stearic acid” manufactured by NOF Corporation.
Note 5: Zinc Hana is “Zinc Hana 1” manufactured by Mitsui Mining & Smelting Co., Ltd.
Note 6: Sulfur is “Seimi sulfur” manufactured by Tsurumi Chemical Co., Ltd.
Note 7: The vulcanization accelerator is “Noxeller NS” (N-tert-butyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinsei Chemical Co., Ltd.

<Production of reinforcing composite>
Reinforcing composites were produced using the ply cords shown in Table 2 and the rubber sheet made of the rubber composition produced by the above-described method according to the formulation shown in Table 1 in the combinations shown in Table 2. Composite material for reinforcement is prepared by immersing the fabric woven with wefts so that the ply cord has a density of 10/10 cm and immersing it in RFL and then bonding the above rubber sheets on top and bottom of the fabric and press-bonding them. The body was made. Two of the obtained composites were attached to each other at right angles and vulcanized at 150 ° C. for 30 minutes to prepare a sample for a peel test of a reinforcing composite. Cuts were made at 25 mm intervals along the direction of the ply cord on the surface of the peel test sample. A peel test was performed on this sample.

<Peel test>
In the above peel test sample, the stress when the two reinforcing composites were peeled off was peeled off by using the Instron method at a rate of 50 mm / min. It was evaluated as (unit: N). The results are shown in Table 2.

Note 8: Ply cord 1 is a tire cord (1840 dtax) in which purified cellulose fiber is twisted.
Note 9: Ply cord 2 is a rayon cord (1840 dtax).

In Comparative Examples 1 and 2 using a rayon cord as a ply cord, a ply cord formed by twisting purified cellulose fiber is used, whereas an adhesive strength in a standard state is 90% or less with respect to an adhesive strength in a completely dry state. In Examples 1 and 2 and Reference Example 1 , the adhesive strength was 100% or more of the absolutely dry state even in the standard state. In particular, in Examples 1 and 2 in which epoxidized natural rubber was blended, the adhesive strength in the standard state was particularly good. From these results, it can be seen that in Examples 1 and 2 , the adhesive strength between the ply cord and the rubber layer can be maintained for a long period of time because there is little decrease in the adhesive strength when placed under operating conditions. Further, in Examples 1 to 3, the absolute value of the adhesive strength was large in both the standard state and the absolutely dry state as compared with Comparative Examples 1 and 2, and the initial adhesive force showed a tendency to be excellent. From these results, by using a combination of a ply cord made of purified cellulose fiber and a rubber layer made of a rubber composition containing natural rubber and silica, a high ratio of non-petroleum resources and a high initial ply cord and rubber layer It can also be seen that a reinforcing composite having excellent long-term adhesive strength can be obtained.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The reinforcing composite of the present invention has a high ratio of non-petroleum resources and excellent long-term strength retention, and can be suitably used as a carcass for pneumatic tires used in, for example, passenger cars, trucks, buses, various heavy machinery and the like.

It is a figure explaining the example of the composite_body | complex for reinforcement which concerns on this invention. It is a figure which shows the right half of sectional drawing of the pneumatic tire which concerns on this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 Composite for reinforcement, 12 Rubber layer, 13 Weave fabric, 14 Ply cord, 15 Weft, 21 Carcass ply, 22 Tread part, 23 Side wall part, 24 Bead part, 25 Bead core, 26 Belt layer

Claims (5)

A reinforcing composite comprising a ply cord made of purified cellulose fiber and a rubber layer, and used as a carcass layer or a belt layer of a pneumatic tire,
The rubber layer is composed of a rubber composition comprising 50 to 90% by mass of natural rubber and 10 to 50% by mass of epoxidized natural rubber , and at least silica as a filler,
The content of the silica is within a range of 20 to 60 parts by mass with respect to 100 parts by mass of the rubber component, and
In the adhesive strength between the ply cord and the rubber layer, the adhesive strength in a standard state at a temperature of 20 ° C. and a relative humidity of 65% is 85% or more of the adhesive strength at a temperature of 120 ° C. and an absolutely dry state. , Composite for reinforcement.   The reinforcing composite according to claim 1, wherein the rubber composition has a ratio of 85 to 100% by mass of the silica in the filler.   The reinforcing composite according to claim 1, wherein the rubber composition contains a silane coupling agent.   A pneumatic tire using the reinforcing composite body according to claim 1 for a carcass.   A pneumatic tire using the reinforcing composite according to claim 1 for a jointless belt layer.

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