JP4871553B2 - Process for producing rubber composition and rubber product obtained thereby - Google Patents

Description

  The present invention relates to a method for producing a rubber composition and a rubber product obtained thereby.

In general, in a vibration-proof rubber used for an engine mount, suspension bush, and the like for supporting an engine of an automobile and suppressing vibration transmission, a low dynamic magnification is required as one of important performances. Yes. Further, when used for automobile tires, durability is also required. Therefore, conventionally, a rubber composition obtained by blending a rubber reinforcing material such as carbon black or silica with a diene rubber has been proposed (see, for example, Patent Document 1).
JP 2004-231905 A

  However, conventional rubber compositions use rubber reinforcing materials such as carbon black and silica, but there are few proposals for enhancing the functionality of these general-purpose rubber reinforcing materials.

  The present invention has been made in view of such circumstances, and for the purpose of enhancing the functionality of rubber, the rubber composition is excellent in reinforcing properties and can suppress reversion of vulcanization. The purpose is to provide the rubber products.

  In order to achieve the above-mentioned object, the present invention involves kneading a diene rubber, fullerene and a peptizer at a temperature of 150 to 200 ° C., grafting the diene rubber to the fullerene, A first gist is a process for producing a rubber composition in which kneaded fullerene and a rubber material containing diene rubber, sulfur and carbon black as essential components are kneaded. Moreover, this invention makes the 2nd summary the rubber product formed by vulcanizing the rubber composition obtained by the said manufacturing method.

  The inventors of the present invention have focused on fullerenes that are chemically and thermally stable and difficult to break, have features such as easy absorption of light energy, high electron acceptability, and radical scavenging ability. Recall that, instead of adding carbon black at the same time as the peptizer, the diene rubber and the peptizer are kneaded in advance at a high temperature and then kneaded with other rubber materials such as carbon black. did. Based on these results, the present inventors have conducted experimental studies, and as a result, kneaded diene rubber, fullerene and peptizer at a temperature of 150 to 200 ° C., and grafted the diene rubber to the fullerene. The inventors have found that the intended purpose can be achieved by kneading the grafted fullerene with a rubber material containing diene rubber, sulfur and carbon black as essential components, and the present invention has been achieved. The reason for this is not clear, but is presumed as follows. That is, when a diene rubber, fullerene, and a peptizer (peptizer) are kneaded at a high temperature of 150 to 200 ° C., the main chain of the diene rubber is cut by the peptizer and radicals are generated. Then, the diene rubber is activated. The radicals in the activated rubber are captured by the fullerene, and the rubber is grafted to the fullerene. As a result, the rubber shape can be maintained even in a high temperature kneading process for the rubber. When the kneading step is performed using the fullerene grafted with the diene rubber chain, the grafted fullerene acts on the carbon black, further improving the reinforcing effect of the carbon black, and returning to vulcanization. Can be suppressed.

  The method for producing the rubber composition of the present invention involves kneading a diene rubber, fullerene, and a peptizer (coughing agent) at a high temperature of 150 to 200 ° C. The main chain is cut, radicals are generated, and the diene rubber is activated. The radicals in the activated rubber are captured by the fullerene, and the rubber is grafted to the fullerene. As a result, the rubber shape can be maintained even in a high-temperature kneading process for the rubber. Since the kneading process is performed using the fullerene grafted with the diene rubber chain, the grafted fullerene acts on the carbon black, further improving the reinforcing effect of the carbon black, and returning to vulcanization. The effect that it can suppress is acquired. Further, by grafting the diene rubber to the fullerene, it is possible to uniformly disperse the fullerene without aggregating.

  And the rubber product formed by vulcanizing the rubber composition obtained by the said manufacturing method is provided with the effect that it is excellent in reinforcement property and can suppress a vulcanization return.

  Next, embodiments of the present invention will be described in detail.

  In the present invention, a diene rubber, a fullerene, and a peptizer are kneaded at a temperature of 150 to 200 ° C., and after the diene rubber is grafted to the fullerene, the grafted fullerene and the diene rubber And a rubber material containing sulfur and carbon black as essential components, to obtain a rubber composition.

  In the present invention, prior to the rubber material kneading step, a diene rubber, fullerene, and a kneading accelerator are kneaded at a high temperature of 150 to 200 ° C. to graft the diene rubber chain. The mastication step of preparing (grafted fullerene) in advance is performed, and this is the greatest feature.

  The method for producing the rubber composition of the present invention will be described in order by dividing it into a kneading step and a kneading step. First, the kneading process in the manufacturing method of the rubber composition of this invention is demonstrated. That is, diene rubber and fullerene are mixed in a solvent such as toluene. In addition, in order to improve the dispersibility of the diene rubber and fullerene in the solvent and suppress the aggregation of both, ultrasonic treatment may be performed as necessary. In some cases, fullerenes previously dispersed in toluene and sonicated may be used. Next, the solvent such as toluene is removed to obtain a mixture (solid content) of diene rubber and fullerene. A predetermined amount of a diene rubber and a kneading accelerator is further added to the mixture, and a predetermined rotor speed (preferably 40 to 40 ° C.) is used at a high temperature of 150 to 200 ° C. using a kneader such as a closed kneader. Kneading at 60 rpm for a predetermined time (preferably 3 to 5 minutes).

  The kneading temperature in the mastication step needs to be set to a high temperature of 150 to 200 ° C, but is preferably in the range of 160 to 180 ° C. That is, if the kneading temperature is less than 150 ° C., the grafting efficiency of the polymer to fullerene is reduced in a short time, and conversely if it exceeds 200 ° C., the rubber has a low molecular weight, which may cause deterioration in physical properties. Because.

  The diene rubber is not particularly limited. For example, natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), ethylene -Propylene-diene rubber (EPDM) and the like. These may be used alone or in combination of two or more. Of these, NR, BR, SBR, and IR are preferably used.

In the present invention, fullerene is a generic term for a carbon atom having a spherical network structure. A typical fullerene, C ₆₀ , consists of 12 5-membered rings and 20 6-membered rings surrounding the 5-membered ring. Each vertex of the network has the same shape as a soccer ball (60). It has a structure in which a carbon atom is located. Its diameter is 1 nm (0.7 nm as a carbon skeleton). The fullerene of the present invention is not limited to the above C _60, is composed of 70 C ₇₀ composed of carbon atoms, 82 carbon C ₈₂ composed of carbon atoms, 124 carbon atoms _C124 etc. are mentioned, and these are used alone or in combination of two or more.

  The blending amount of fullerene in the mastication step is preferably in the range of 1 to 20 parts, particularly preferably in the range of 2 to 10 parts, with respect to 100 parts by weight of diene rubber (hereinafter abbreviated as “part”). is there. That is, if the blending amount of the fullerene is less than 1 part, the reinforcing effect on the rubber becomes insufficient. Conversely, if it exceeds 20 parts, the material cost of the rubber tends to increase.

  Further, the peptizer (peptizer) is not particularly limited as long as the effect as a peptizer for diene rubber can be obtained at a high temperature of 150 to 200 ° C., for example, o, o'-dibenzamide diphenyl disulfide, zinc salt of 2-benzamidothiophenol, a mixture of diaryl sulfide, and the like. These may be used alone or in combination of two or more.

  Although the compounding quantity with respect to fullerene of the kneading promoter in the said mastication process is not specifically limited, The inside of the range of 0.01-1 part is preferable with respect to 1 part of fullerene, Most preferably, it is 0.1-1. Within the range of the part. That is, when the blending amount of the peptizer is less than 0.01 part, the reaction time tends to be long when the diene rubber is grafted to the fullerene, and conversely, This is because when the amount exceeds 1 part, the molecular weight of the polymer is excessively reduced and the elongation at break tends to decrease.

  Next, the kneading step in the process for producing the rubber composition of the present invention will be described. That is, the grafted fullerene prepared in the mastication step and a rubber material containing diene rubber, sulfur and carbon black as essential components are blended at a predetermined ratio, and these are mixed in a closed kneader or the like. The rubber composition can be prepared by kneading at a predetermined temperature (preferably 130 to 170 ° C.) for a predetermined time (preferably 3 to 5 minutes).

  Examples of the diene rubber include those similar to the diene rubber used in the aforementioned kneading step. The diene rubber in the kneading step and the diene rubber in the kneading step may be the same type of diene rubber or different types of diene rubber. In the present invention, it is preferable to use isoprene-based rubber as the diene rubber in the mastication step and natural rubber as the diene rubber in the kneading step.

  In addition, the compounding ratio of the diene rubber (a) in the mastication step and the diene rubber (b) in the kneading step is a weight ratio in the range of a / b = 10/90 to 80/20. Is particularly preferable, and a / b = 20/80 to 50/50.

  The blending amount of the diene rubber is based on 100 parts of the total amount (a + b) of the diene rubber (a) in the mastication step and the diene rubber (b) in the kneading step. Is preferably adjusted so as to be in the range of 0.5 to 10 parts, and in particular, the amount of the diene rubber is adjusted so that the amount of the fullerene is in the range of 1 to 8 parts. preferable. That is, if the final blending amount of fullerene is less than 0.5 parts, the reinforcing property of the rubber becomes insufficient. Conversely, if the final blending amount of fullerene exceeds 10 parts, the rubber material cost increases. This is because there is a tendency.

  The carbon black is not particularly limited, and examples thereof include various grades of carbon black such as SAF class, ISAF class, HAF class, MAF class, FEF class, GPF class, SRF class, FT class, and MT class. . These may be used alone or in combination of two or more.

  The blending amount of carbon black in the kneading step is preferably in the range of 10 to 100 parts, particularly preferably in the range of 30 to 80 parts, with respect to 100 parts of the diene rubber. That is, if the blending amount of the carbon black is less than 10 parts, the support performance of the rubber is small. Conversely, if the blending amount of the carbon black exceeds 100 parts, the Mooney viscosity increases and the processability tends to deteriorate. Because it is seen.

  Further, the amount of sulfur in the kneading step is preferably in the range of 0.1 to 7 parts, particularly preferably in the range of 0.5 to 5 parts, with respect to 100 parts of the diene rubber. That is, if the amount of sulfur is less than 0.1 part, the crosslinking density is insufficient and the physical properties are low, and conversely if the amount of sulfur exceeds 7 parts, the heat resistance tends to deteriorate. Because.

  In the kneading step, a vulcanization accelerator, a vulcanization aid, an anti-aging agent, a processing aid, a softening agent, etc. are appropriately blended with the diene rubber, sulfur and carbon black as necessary. There is no problem.

  The vulcanization accelerator is not particularly limited, and examples thereof include thiazole series, sulfenamide series, thiuram series, aldehyde ammonia series, aldehyde amine series, guanidine series, and thiourea series vulcanization accelerators. These may be used alone or in combination of two or more. Among these, a sulfenamide-based vulcanization accelerator is preferable from the viewpoint of excellent crosslinking reactivity.

  Examples of the thiazole vulcanization accelerator include dibenzothiazyl disulfide (MBTS), 2-mercaptobenzothiazole (MBT), 2-mercaptobenzothiazole sodium salt (NaMBT), and 2-mercaptobenzothiazole zinc salt (ZnMBT). Etc. These may be used alone or in combination of two or more. Among these, dibenzothiazyl disulfide (MBTS) is preferably used because it is particularly excellent in cross-linking reactivity.

  Examples of the sulfenamide-based vulcanization accelerator include N-cyclohexyl-2-benzodiallylsulfenamide, N-cyclohexyl-2-benzothiazylsulfenamide (CBS), N-oxydiethyl-2-benzo Examples thereof include thiazole sulfenamide (OBS), Nt-butyl-2-benzothiazoyl sulfenamide (BBS), N, N′-dicyclohexyl-2-benzothiazoyl sulfenamide, and the like.

  Examples of the thiuram vulcanization accelerator include tetramethyl thiuram disulfide (TMTD), tetraethyl thiuram disulfide (TETD), tetrabutyl thiuram disulfide (TBTD), and the like.

  The blending amount of the vulcanization accelerator is preferably in the range of 0.3 to 7 parts, particularly preferably in the range of 0.5 to 5 parts, with respect to 100 parts of the diene rubber. That is, if the vulcanization accelerator is less than 0.3 part, the crosslinking reactivity tends to be inferior, and conversely if the vulcanization accelerator exceeds 7 parts, the physical properties of rubber (breaking strength, breaking elongation) decrease. It is because there is a possibility of doing.

  The vulcanization aid is not particularly limited, and examples thereof include zinc white (ZnO) and magnesium oxide. These may be used alone or in combination of two or more.

  The compounding amount of such a vulcanization aid is preferably in the range of 1 to 20 parts, particularly preferably in the range of 3 to 10 parts, with respect to 100 parts of the diene rubber.

  Examples of the anti-aging agent include carbamate anti-aging agents, phenylenediamine anti-aging agents, phenol anti-aging agents, diphenylamine anti-aging agents, quinoline anti-aging agents, imidazole anti-aging agents, and waxes. Etc.

  The amount of such an anti-aging agent is preferably in the range of 1 to 7 parts, particularly preferably in the range of 2 to 5 parts, with respect to 100 parts of the diene rubber.

  Examples of processing aids include stearic acid, fatty acid esters, fatty acid amides, hydrocarbon resins, and the like.

  The amount of such a processing aid is preferably in the range of 1 to 5 parts, particularly preferably in the range of 1 to 3 parts, with respect to 100 parts of the diene rubber.

  The rubber product of the present invention can be obtained by subjecting the rubber composition obtained as described above to press vulcanization under predetermined conditions.

  The use of the rubber product of the present invention is not particularly limited, but it can be suitably used for tires, engine mounts, stabilizer bushes, suspension bushings, industrial vibration-proof rubbers, rubber hoses and the like used in vehicles such as automobiles.

  Next, examples will be described together with comparative examples. However, the present invention is not limited to these examples.

  First, prior to the examples and comparative examples, the following materials were prepared.

[Isoprene rubber]
IR2200, manufactured by Nippon Zeon

[Fullerene]
Frontier Carbon Co., nanom mix MF-S [Main component: Mixture of C ₆₀ and C ₇₀ (85 wt%), other higher fullerenes (15 wt%)]

[Kneading accelerator]
Mixture of diaryl sulfides (manufactured by Ouchi Shinsei Chemical Industry Co., Ltd., Noctizer SD-T)

[Natural rubber]
RSS # 3 [ML _{1 + 4} (100 ° C.): 65]

〔Carbon black〕
FEF grade carbon black (manufactured by Tokai Carbon Co., Seast SO)

[Zinc oxide]
Mitsui Metal Mining Co., Ltd., zinc oxide

〔stearic acid〕
Made by Kao, Lunac S30

[Vulcanization accelerator (CBS)]
N-cyclohexyl-2-benzodiallylsulfenamide (manufactured by Sanshin Chemical Industry Co., Ltd., Noxeller CZ-G)

〔sulfur〕
Sulfax200S manufactured by Tsurumi Chemical Co., Ltd.

  Next, various batches were produced using the above materials.

[Preparation of batch A]
Fullerene 2.8 g and isoprene rubber 20 g were mixed in toluene. Next, toluene was removed to obtain a mixture (solid content) of isoprene rubber and fullerene. To this mixture, 50 g of isoprene rubber and 1.4 g of a kneading accelerator were further added, and the mixture was mixed at a temperature of 160 ° C. and a rotor rotation speed of 60 rpm using a closed kneader (manufactured by Toyo Seiki Seisakusho, 100 cc lab plast mill). Kneaded for about minutes.

[Preparation of batch B]
It was produced in the same manner as in Batch A except that the blending amount of the fullerene was changed to 7 g.

[Preparation of batch C]
Fullerene 2.8 g and isoprene rubber 20 g were mixed in toluene. Next, toluene was removed to obtain a mixture (solid content) of isoprene rubber and fullerene. To this mixture, 50 g of isoprene rubber and 0.28 g of a kneading accelerator were further added, and the mixture was mixed at a temperature of 150 ° C. and a rotor rotation speed of 60 rpm using a closed kneader (manufactured by Toyo Seiki Seisakusho, 100 cc lab plast mill). Kneaded for about minutes.

[Preparation of batch D]
Fullerene 2.8 g and isoprene rubber 20 g were mixed in toluene. Next, toluene was removed to obtain a mixture (solid content) of isoprene rubber and fullerene. To this mixture, 50 g of isoprene rubber and 2.8 g of a kneading accelerator were further added, and the mixture was used at a temperature of 200 ° C. and a rotor rotation speed of 60 rpm using a closed kneader (manufactured by Toyo Seiki Seisakusho, 100 cc lab plast mill). Kneaded for about minutes.

[Preparation of batch a]
Fullerene 2.8 g and isoprene rubber 20 g were mixed in toluene. Next, toluene was removed to obtain a mixture (solid content) of isoprene rubber and fullerene. To this mixture, 50 g of isoprene rubber and 1.4 g of a kneading accelerator were further added, and 1 ml at a temperature of 140 ° C. and a rotor rotation speed of 60 rpm using a closed kneader (manufactured by Toyo Seiki Seisakusho, 100 cc lab plast mill). Kneaded for about minutes.

[Preparation of batch b]
Fullerene 2.8 g and isoprene rubber 20 g were mixed in toluene. Next, toluene was removed to obtain a mixture (solid content) of isoprene rubber and fullerene. To this mixture, 50 g of isoprene rubber and 1.4 g of a kneading accelerator were further added, and the mixture was sealed at a temperature of 210 ° C. and a rotor speed of 60 rpm using a closed kneader (manufactured by Toyo Seiki Seisakusho, 100 cc lab plast mill). Kneaded for about minutes.

[Example 1]
The components shown in Table 1 below are blended in the proportions shown in the same table, and rubber, batch, carbon black, zinc oxide, and stearic acid are mixed using a closed kneader (Toyo Seiki Seisakusho, 600cc Lab Plast Mill). The set temperature of the closed kneader was set to 100 ° C. and kneaded for 3 minutes. Thereafter, using a roll (manufactured by Kansai Roll Co., Ltd., 6 inch test roll), a vulcanization accelerator and sulfur were kneaded to prepare a rubber composition.

[Examples 2-6, Comparative Examples 1-4]
A rubber composition was prepared in the same manner as in Example 1 except that the type or amount of each component was changed to those shown in Tables 1 and 2 below.

  Using the rubber compositions of Examples and Comparative Examples thus obtained, each characteristic was evaluated according to the following criteria. These results are shown in Tables 1 and 2 below.

[Normal properties]
Each rubber composition was press-molded under conditions of 150 ° C. × 20 minutes and punched with a JIS No. 5 dumbbell to produce a rubber sheet having a thickness of 2 mm. Then, using this rubber sheet, 100% modulus (M100), breaking strength (TB), breaking elongation (EB), and hardness (Hs: JIS A) were measured according to JIS K 6251.

[Return to vulcanization]
For the rubber compositions of Example 1 and Comparative Example 1, the vulcanization behavior at a temperature of 150 ° C. was measured using a rotorless rheometer (ROTORLESS RHEOMETER RLR-2 manufactured by Toyo Seiki Seisakusho Co., Ltd.) to evaluate the reversion. went. The results are shown in FIG. In FIG. 1, the horizontal axis represents time (min) and the vertical axis represents torque (kgf · cm).

  From the above results, the Example products were excellent in normal physical properties. Further, from the results of FIG. 1, the product of Example 1 has a substantially constant torque and the vulcanization return is suppressed, whereas the product of Comparative Example 1 gradually decreases in torque and the vulcanization return occurs. It was. In addition, since the example product can obtain a sufficient reinforcing effect by using fullerene, a low-filling blend of carbon black is possible, and the weight of the rubber product can be reduced.

  Comparing the product of Comparative Example 1 with the product of Example, the product of Comparative Example 1 does not perform the mastication step (batch treatment) and uses carbon black instead of fullerene, and therefore 100% modulus (M100). And the hardness was inferior to that of Example 1. Moreover, since the comparative example 2 goods did not perform the mastication process (batch process), 100% modulus (M100) was inferior to Example 3,4. Since the comparative example 3 product uses a batch a having a low kneading temperature and a short kneading time, sufficient reinforcing properties were not ensured. The comparative example 4 product used the batch b having a kneading temperature too high and a long kneading time, so that the rubber had a low molecular weight and the elongation at break was small.

  The rubber product obtained by the production method of the present invention can be suitably used for tires, engine mounts, stabilizer bushes, suspension bushings, industrial vibration-proof rubbers, rubber hoses and the like used in vehicles such as automobiles.

It is a graph which shows the evaluation result of vulcanization return.

Claims (3)

  A diene rubber, fullerene and a peptizer are kneaded at a temperature of 150 to 200 ° C., and after the diene rubber is grafted to the fullerene, the grafted fullerene, the diene rubber, sulfur and carbon A method for producing a rubber composition, comprising kneading a rubber material containing black as an essential component. The diene rubber grafted to fullerene and the diene rubber kneaded with grafted fullerene are natural rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, and ethylene-propylene- The process for producing a rubber composition according to claim 1, wherein the rubber composition is at least one selected from the group consisting of diene rubbers.   A rubber product obtained by vulcanizing a rubber composition obtained by the production method according to claim 1 or 2.