JP2016003292A - Rubber composition and pneumatic tire using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bead filler rubber composition that solves the dilemma in which: the bead filler is required also to be high hardness as well as low heat generation; although the method in which the incorporation amount of carbon black is increased is known as the common means of increasing the hardness of a vulcanized rubber, there is a problem that the heat generation worsens, also the viscosity of unvulcanized rubber composition increases, the load on the processing such as kneading and extrusion becomes large, and the processability worsens; and on the other hand, when the incorporation amount of carbon black is decreased, the heat generation is improved but the high hardness is not obtained in this case.SOLUTION: The problem was solved by a rubber composition in which 1 to 30 pts.mass of C-based petroleum resin modified with a phenolic compound having a weight average molecular weight Mw of 200 to 1000 and a softening point in a range of -40 to 20°C, 40 to 100 pts.mass of carbon black, 1 to 20 pts.mass of thermosetting resin, and 0.1 to 10 pts.mass of hardening agent are incorporated into 100 pts.mass of a diene-based rubber.

Description

  The present invention relates to a rubber composition and a pneumatic tire using the same, and more particularly to a rubber composition capable of simultaneously improving all of hardness, heat generation, and processability and a pneumatic tire using the same. It is.

The bead filler needs to have high hardness in order to suppress the movement and separation of the bead core and the rolled-up portion of the carcass layer. On the other hand, low heat generation is also required.
As a general technique for increasing the hardness of vulcanized rubber, a method of blending a phenolic resin and a curing agent is known (see, for example, Patent Document 1). Aside from this, a method of increasing the amount of carbon black is also known, but exothermicity deteriorates, the viscosity of the unvulcanized rubber composition increases, and the load on processes such as kneading and extrusion is increased. There is a problem that the processability is deteriorated. On the other hand, if the blending amount of carbon black is reduced, the heat build-up can be improved, but in this case, high hardness cannot be obtained.
In order to improve the deterioration of workability due to the increase in the amount of carbon black, there is a means for increasing the amount of oil. In this case, both the hardness and the exothermicity are deteriorated.
As described above, it is recognized that it is a difficult matter in the industry to obtain a rubber composition that can simultaneously improve all of hardness, heat generation, and processability.

US Pat. No. 5,226,987

  Accordingly, an object of the present invention is to provide a rubber composition capable of simultaneously improving all of hardness, heat generation and processability, and a pneumatic tire using the same.

The present inventors have results of extensive research with respect to the diene rubber, phenolic compounds modified with C ₉ petroleum resins with specific properties, carbon black, a thermosetting resin and a curing agent with a specific amount It has been found that the above-mentioned problems can be solved by blending, and the present invention has been completed.
That is, the present invention is as follows.

1. To diene rubber 100 parts by weight, the weight average molecular weight Mw of 200 to 1000, and a softening point in the range of -40~20 ℃, 1~30 mass _{C 9} petroleum resins modified with phenolic compounds A rubber composition comprising 40 to 100 parts by mass of carbon black, 1 to 20 parts by mass of a thermosetting resin, and 0.1 to 10 parts by mass of a curing agent.
2. The phenolic compounds modified with C ₉ petroleum resin is a rubber composition according to the 1, which is a C ₉ petroleum resin modified with phenol.
3. 3. The rubber as described in 1 or 2 above, wherein the thermosetting resin is a novolac type phenol resin, or a novolac type phenol resin, a novolac type cresol resin, a novolac type resorcin resin, or a mixture thereof. Composition.
4). The curing agent is any one of hexamethylenetetramine, HMMM (partial condensate of hexamethoxymethylol melamine), PMMM (partial condensate of hexamethylol melamine pentamethyl ether), or a mixture thereof. The rubber composition in any one of -3.
5. The rubber composition as described in any one of 1 to 4 above, wherein the rubber composition after vulcanization has a hardness (hardness measured at 20 ° C. in accordance with JIS K6253) of 65 or more.
6). A pneumatic tire using the rubber composition according to any one of 1 to 5 as a bead filler.

According to the present invention, to the diene rubber, phenolic compounds modified with C ₉ petroleum resins with specific properties, carbon black, since the thermosetting resin and a curing agent was blended with a specific amount, hardness, It is possible to provide a rubber composition capable of simultaneously improving both heat generation and processability and a pneumatic tire using the same.

  Hereinafter, the present invention will be described in more detail.

(Diene rubber)
As the diene rubber used in the present invention, any diene rubber that can be blended in the rubber composition can be used, for example, natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR). Styrene-butadiene copolymer rubber (SBR), acrylonitrile-butadiene copolymer rubber (NBR), ethylene-propylene-diene terpolymer (EPDM), and the like. These may be used alone or in combination of two or more. The molecular weight and microstructure are not particularly limited, and may be terminally modified with an amine, amide, silyl, alkoxysilyl, carboxyl, hydroxyl group or the like, or may be epoxidized.
Among these diene rubbers, NR and SBR are particularly preferable as the diene rubber from the viewpoint of the effect of the present invention. As the diene rubber, it is preferable to use a non-hydrogenated rubber.

(Modified C ₉ petroleum resin with a phenol compound)
_{C 9} petroleum resins modified with phenolic compounds used in the present invention has a weight average molecular weight Mw of 200 to 1000, and a softening point in the range of -40~20 ℃. Also, the C ₉ petroleum resin is a liquid at room temperature.
As is well known, the C ₉ petroleum resin is an aromatic petroleum resin obtained by (co) polymerizing a C ₉ fraction obtained by thermal decomposition of naphtha. Typical C ₉ petroleum resin, styrene, vinyl toluene, and a-methyl styrene, indene, one or more selected from methyl indene and dicyclopentadiene as monomer units.
C ₉ petroleum resins modified with phenolic compounds used in the present invention can be obtained by cationic polymerization of the C ₉ fraction in the presence of a phenol-based compound. Examples of the phenolic compound include phenol, cresol, xylenol, pt-butylphenol, p-octylphenol, p-nonylphenol, and the like. Among them, phenol is preferable from the viewpoint of improving the effect of the present invention.
Here, the weight average molecular weight Mw of C ₉ petroleum resins modified with phenolic compounds is greater than 200 less than or 1000, hardness, pyrogenic, it is impossible to improve all processability simultaneously. Even when the softening point is less than −40 ° C. or exceeds 20 ° C., all of hardness, exothermicity and workability cannot be improved at the same time.
The weight average molecular weight is measured by a GPC method in terms of polystyrene, and the softening point is measured by a ring and ball method defined in JIS K6220-1.
Incidentally, _{C 9} petroleum resins modified with phenolic compounds used in the present invention may be used those commercially available, for example, Rutgers Co. Nobaresu L100, Nobaresu L800, Nobaresu A1200, etc. Nobaresu LC60 is cited It is done.
By blending the modified C ₉ petroleum resin with a phenol-based compound increases the dispersibility of carbon black, also by joining the cross-linking reaction of the thermosetting resin, it is presumed that the desired properties are expressed.

(Carbon black)
The carbon black used in the present invention preferably has a nitrogen adsorption specific surface area (N ₂ SA) of 20 to 150 m ² / g from the viewpoint of simultaneously improving all of hardness, exothermicity and workability. More preferably, it is -120 m < ² > / g.
The nitrogen adsorption specific surface area (N2SA) is determined according to JIS K6217-2.

(Thermosetting resin)
The thermosetting resin used in the present invention is preferably a novolak-type phenolic resin, specifically, any of a novolak-type phenol resin, a novolac-type cresol resin, a novolac-type resorcin resin, an oil-modified phenol resin, or those Of the mixture.
Moreover, the novolak-type phenol resin used by this invention can utilize what is marketed, for example, Taoka Chemical Industry Co., Ltd. Sumikanol 610,620, Indian specification company Penacolite resin B-18- S, Sumitomo Bakelite Co., Ltd. PR-YR-170 etc. are mentioned.

(Curing agent)
The rubber composition of the present invention contains a curing agent. Although it does not restrict | limit especially as a hardening | curing agent, For example, from a viewpoint of the effect of this invention, hexamethylenetetramine, HMMM (partial condensate of hexamethoxymethylol melamine), PMMM (partial condensate of hexamethylol melamine pentamethyl ether), hexaethoxy Examples thereof include methyl melamine, a polymer of para-formaldehyde, and an N-methylol derivative of melamine. From the viewpoint of the effects of the present invention, one or more selected from the group consisting of hexamethylenetetramine, HMMM, and PMMM are preferable.

(Rubber composition ratio)
The rubber composition of the present invention has a weight average molecular weight Mw of 200 to 1000 and a softening point in the range of −40 to 20 ° C. with respect to 100 parts by mass of diene rubber, and C ₉ modified with a phenol compound. 1 to 30 parts by mass of a petroleum petroleum resin, 40 to 100 parts by mass of carbon black, 1 to 20 parts by mass of a thermosetting resin, and 0.1 to 10 parts by mass of a curing agent.
If the amount of the C ₉ petroleum resins modified with the phenolic compound is less than 1 part by mass, it is impossible to achieve the effect of the present invention too small, amount. On the other hand, when it exceeds 30 parts by mass, the hardness and exothermicity deteriorate.
When the blending amount of the carbon black is less than 40 parts by mass, the hardness deteriorates, and when it exceeds 100 parts by mass, the exothermic property and workability deteriorate.
When the blending amount of the thermosetting resin is less than 1 part by mass, the hardness deteriorates, and when it exceeds 20 parts by mass, the exothermic property and workability deteriorate.
Hardness will deteriorate that the compounding quantity of a hardening | curing agent is less than 0.1 mass part, and exothermic property and workability will deteriorate when it exceeds 10 mass parts.

A further preferred amount of the C ₉ petroleum resins modified with the phenolic compound to the diene rubber 100 parts by weight, from 5 to 30 parts by weight.
A more preferable blending amount of the carbon black is 50 to 90 parts by mass with respect to 100 parts by mass of the diene rubber.
The more preferable amount of the thermosetting resin is 5 to 20 parts by mass with respect to 100 parts by mass of the diene rubber.
The more preferable compounding amount of the curing agent is 0.5 to 5 parts by mass with respect to 100 parts by mass of the diene rubber.

(Other ingredients)
In the rubber composition of the present invention, in addition to the above-described components, a vulcanization or crosslinking agent; a vulcanization or crosslinking accelerator; various fillers such as zinc oxide, clay, talc, calcium carbonate; an anti-aging agent; Various additives that are generally blended in rubber compositions such as additives can be blended, and these additives are kneaded by a general method into a composition and used for vulcanization or crosslinking. Can do. The blending amounts of these additives can be set to conventional general blending amounts as long as the object of the present invention is not violated.

  The rubber composition of the present invention is suitable for producing a pneumatic tire according to a conventional method for producing a pneumatic tire, and the hardness of the rubber composition after vulcanization (measured at 20 ° C. according to JIS K6253). Is not less than 65, and the heat generation and workability can be improved at the same time.

  EXAMPLES Hereinafter, although an Example and a comparative example further demonstrate this invention, this invention is not restrict | limited to the following example.

Examples 1-3 and Comparative Examples 1-9
Sample Preparation In the formulation (parts by mass) shown in Table 1, the components except the vulcanization accelerator and sulfur were kneaded for 5 minutes with a 1.7 liter closed Banbury mixer, and then added with the vulcanization accelerator and sulfur. The rubber composition was obtained by kneading. Next, the obtained rubber composition was press vulcanized in a predetermined mold at 160 ° C. for 20 minutes to obtain a vulcanized rubber test piece, and an unvulcanized rubber composition and vulcanized rubber were tested by the following test method. The physical properties of the test piece were measured.

Exothermic property (tan δ (60 ° C.)): In accordance with JIS K6394, using a viscoelastic spectrometer manufactured by Toyo Seiki Co., Ltd., elongation deformation strain rate = 10%, amplitude = ± 2%, frequency = 20 Hz, temperature Tan δ (60 ° C.) was measured under the condition of 60 ° C., and the exothermic property was evaluated with this value. The results are shown as an index with Comparative Example 1 as 100. A larger index indicates a lower exothermic property.
Hardness: measured at 20 ° C. according to JIS K6253.
Mooney viscosity: The viscosity of unvulcanized rubber at 100 ° C. was measured in accordance with JIS K6300 using the rubber composition. The result was expressed as an index with the value of Comparative Example 1 as 100. The larger the index, the lower the viscosity and the better the workability.
The results are also shown in Table 1.

* 1: NR (STR20)
* 2: SBR (Nipol 1502 manufactured by Zeon Corporation)
* 3: Carbon black (Toast Carbon Co., Ltd. Seest F, nitrogen adsorption specific surface area (N ₂ SA) = 40 m ² / g)
* 4: Zinc oxide (3 types of zinc oxide manufactured by Shodo Chemical Industry Co., Ltd.)
* 5: Stearic acid (bead stearic acid manufactured by NOF Corporation)
* 6: Anti-aging agent (VULKANOX manufactured by LANXESS)
* 7: Thermosetting resin (Novolac cresol resin, Sumikanol 610, manufactured by Taoka Chemical Co., Ltd.)
* 8: Curing agent (Sanshin Chemical Industry Co., Ltd. hexamethylenetetramine, Sunseller HT-P0)
* 9: Oil (Extract No. 4 S manufactured by Showa Shell Sekiyu KK)
* 10: Resin -1 (Rutgers Co. Nobaresu L800, phenol modified with _{C 9} petroleum resin, Mw = 300, softening point -40 to-30 ° C., hydroxyl value = 0.1 wt%, liquid at room temperature)
* 11: Resin-2 (Rutgers Novales C90, Coumarone Indene resin, Mw = 2000, softening point 20-30 ° C., hydroxyl value = 0.0 wt%, solid at room temperature)
* 12: Sulfur (fine powder sulfur with Jinhua seal oil manufactured by Tsurumi Chemical Co., Ltd. (sulfur content 95.24% by mass))
* 13: Vulcanization accelerator (SANTOCURE CBS manufactured by FLEXSYS)

As is clear from the results of Table 1 above, the rubber compositions obtained in Examples 1 to 3 were C ₉ petroleum resins and carbons modified with a phenolic compound having specific characteristics with respect to the diene rubber. Since black, a thermosetting resin, and a curing agent are blended in specific amounts, it has been found that all of hardness, heat generation, and workability can be improved simultaneously with respect to the conventional representative comparative example 1.
In contrast, Comparative Example 2, without the use of modified C ₉ petroleum resin with a phenol-based compound, because it is an example of using the unmodified coumarone-indene resin to that instead, is exothermic and workability deteriorate did.
Comparative Example 3, since the amount of modified C ₉ petroleum resin in the phenolic compound is less than the lower limit defined in the present invention, workability was deteriorated.
Comparative Example 4, since the amount of C ₉ petroleum resins modified with phenolic compounds is greater than the upper limit defined in the present invention, hardness and heat resistance is deteriorated.
In Comparative Example 5, since the blending amount of carbon black was less than the lower limit specified in the present invention, the hardness deteriorated.
In Comparative Example 6, the exothermic property and workability deteriorated because the blending amount of carbon black exceeded the upper limit defined in the present invention.
Comparative Example 7 does not use the C ₉ petroleum resin modified with phenolic compounds, since an example in which increasing the amount of oil that instead, hardness and heat resistance is deteriorated.
In Comparative Example 8, since the blending amount of the thermosetting resin and the curing agent was less than the lower limit specified in the present invention, the hardness deteriorated.
Since the compounding quantity of the thermosetting resin and the hardening | curing agent exceeded the upper limit prescribed | regulated by this invention in the comparative example 9, exothermic property and workability deteriorated.

Claims (6)

To diene rubber 100 parts by weight, the weight average molecular weight Mw of 200 to 1000, and a softening point in the range of -40~20 ℃, 1~30 mass _{C 9} petroleum resins modified with phenolic compounds A rubber composition comprising 40 to 100 parts by mass of carbon black, 1 to 20 parts by mass of a thermosetting resin, and 0.1 to 10 parts by mass of a curing agent. The phenolic compounds modified with C ₉ petroleum resin is a rubber composition according to claim 1, characterized in that the modified C ₉ petroleum resin with phenol.   3. The thermosetting resin according to claim 1, wherein the novolac type phenol resin is any one of a novolac type phenol resin, a novolac type cresol resin, a novolac type resorcin resin, or a mixture thereof. Rubber composition.   The curing agent is any one of hexamethylenetetramine, HMMM (partial condensate of hexamethoxymethylolmelamine), PMMM (partial condensate of hexamethylolmelamine pentamethyl ether), or a mixture thereof. The rubber composition in any one of 1-3.   The rubber composition according to any one of claims 1 to 4, wherein the rubber composition after vulcanization has a hardness (hardness measured at 20 ° C in accordance with JIS K6253) of 65 or more. .   A pneumatic tire using the rubber composition according to claim 1 as a bead filler.