JP5018664B2 - Method for producing elastomer composition and pneumatic tire using the same - Google Patents

Description

  The present invention relates to a method for producing an elastomer composition and a pneumatic tire using the same, and more particularly to a method for producing an elastomer composition in which ultraviolet deterioration is suppressed and a pneumatic tire using the same for, for example, an inner liner.

  Elastomer compositions blended with butyl rubber and nylon are well known. However, butyl rubber has low resistance to ultraviolet rays, and has a problem that it deteriorates when exposed to sunlight and its mechanical properties are remarkably lowered. As a prescription for preventing UV degradation, it is common to add an amine or phenolic anti-aging agent (see Patent Document 1), which reacts with rubber or nylon and adversely affects the blend of rubber and nylon. For this reason, the butyl rubber / nylon blend system has a limit in use, and a sufficient effect of preventing UV deterioration cannot be obtained. In addition, it is known that when carbon black is blended with rubber (see Patent Document 2), in the rubber / nylon blend system, carbon black in the rubber becomes a defect and lowers durability. There is a problem and there is a limit to the amount of compounding, and this also fails to obtain a sufficient UV protection effect.

JP 2000-103917 A Special table 2001-512167 gazette

  Accordingly, an object of the present invention is to suppress an ultraviolet deterioration of an elastomer composition obtained by blending the above-mentioned butyl rubber and a nylon resin, and to endure long-term outdoor exposure, and an air using the same. The purpose is to provide tires.

  According to the present invention, (i) brominated product of isobutylene and paramethylstyrene copolymer rubber or (ii) at least one rubber selected from butyl rubber, halogenated butyl rubber and polyisobutylene rubber, isobutylene and paramethylstyrene copolymer rubber Butyl rubber (A), which is a blend with a brominated product of is a dispersed phase, and is selected from at least one selected from nylon 11, nylon 6/66 copolymer, nylon 6 and nylon 66, or a blend thereof. In the matrix phase of the butyl rubber / nylon resin blend composition in which the nylon resin (B) is a matrix phase, 2.5 to 8% by weight of titanium oxide (C) is blended with respect to the weight of the nylon resin (B). In the production of the elastomer composition, the resin (B) and titanium oxide (C) to be blended are added. Blending in a first step, the manufacturing method of the next resultant blend and the rubber (A) and elastomer composition characterized by mixing a is provided Te.

  According to the present invention, there is further provided a pneumatic tire using the elastomer composition produced by the above method as an inner liner.

  According to the present invention, even when an elastomer composition blended with butyl rubber (A) / nylon resin (B) is used as an inner liner for a tire, the tire is displayed outdoors at a store such as a store for a long period of time. However, since it is possible to prevent the rubber from being deteriorated by ultraviolet rays, the rubber can be used without deteriorating its characteristics. In addition, there is an example in which a release agent containing carbon black is applied to the inner surface of the tire for the convenience of manufacturing the tire. In this case, the presence of the release agent on the inner liner surface of the pneumatic tire causes the ultraviolet ray of rubber. Although degradation is prevented to some extent, according to the present invention, ultraviolet degradation can be suppressed without using a carbon black-containing release agent, so that stable characteristics can be imparted to a pneumatic tire as an inner liner. it can.

  As a result of researches to solve the above problems, the present inventors have found that (i) a brominated product of isobutylene and paramethylstyrene copolymer rubber or (ii) at least one selected from butyl rubber, halogenated butyl rubber and polyisobutylene rubber. A butyl rubber (A), which is a blend of a rubber of the above, isobutylene and a brominated product of paramethylstyrene copolymer rubber, is selected from nylon 11, nylon 6/66 copolymer, nylon 6 and nylon 66. In the matrix phase of the butyl rubber / nylon resin blend composition in which the nylon resin (B) selected from at least one or a blend thereof is used as the matrix phase, titanium oxide (C) is added to the weight of the nylon resin (B). In the production of an elastomer composition containing 2.5 to 8% by weight, ) And blended with all of the titanium oxide first step, by kneading then the resulting blend and the rubber (A), found that it is possible to achieve the object.

  According to the present invention, by adding 2.5 to 8% by weight of titanium oxide (i.e., titanium dioxide, hereinafter the same) in the nylon resin (B) serving as a matrix, the butyl rubber (A) that is vulnerable to ultraviolet rays is added. Deterioration due to ultraviolet irradiation can be prevented without suppressing UV transmission and without reducing durability. Titanium oxide is generally used as a white colorant in a compounding amount of about 0.5 to 1.5% by weight with respect to the resin. The prevention effect cannot be obtained, and if it is too much, it becomes a defect and the durability is lowered. % By weight.

  When the present inventors compound titanium oxide with rubber, the durability of the rubber composition tends to deteriorate, and when titanium oxide is not sufficiently dispersed in the resin, the durability tends to deteriorate due to poor dispersion. As a result, it was found that the resin and titanium oxide need to be blended first. In order to improve the dispersion of titanium oxide in the resin, a commercially available resin master batch containing titanium oxide can be used, and the viscosity of the system increases due to the reaction between the rubber and the resin, so that the kneading of the rubber and the resin At the same time, when titanium oxide was added at the same time, it was found that the titanium oxide in the masterbatch could not be sufficiently diffused throughout the resin, resulting in poor dispersion and impaired durability. On the other hand, the main cause of the deterioration of the rubber composition is the decomposition of rubber molecules by ultraviolet rays, so that it is more effective to blend in the matrix resin than in the rubber, so that the ultraviolet rays can be effectively prevented. I found it.

  According to the present invention, titanium oxide can be uniformly dispersed in the resin by previously blending titanium oxide and the resin at a final concentration, and it is weak against ultraviolet rays by effectively blending titanium oxide in the resin matrix. It is possible to prevent ultraviolet rays from being transmitted to butyl rubber, prevent poor dispersion, and prevent deterioration while maintaining durability.

  As the titanium oxide used as the component (C) in the elastomer composition of the present invention, anatase type and rutile type are well known, but rutile type is preferable for preventing ultraviolet rays.

  The butyl rubber (A) constituting the dispersed phase in the elastomer composition of the present invention is selected from (i) brominated product of isobutylene and paramethylstyrene copolymer rubber or (ii) butyl rubber, halogenated butyl rubber and polyisobutylene rubber. And a brominated product of at least one rubber, isobutylene, and paramethylstyrene copolymer rubber, all of which are readily available as commercial products. Among these, the use of brominated products of isobutylene and paramethylstyrene copolymer rubber is preferable from the viewpoint of compatibility with nylon and heat resistance.

  Examples of the nylon resin (B) constituting the matrix phase in the elastomer composition of the present invention include at least one selected from nylon 11, nylon 6/66 copolymer, nylon 6 and nylon 66, or a blend thereof. These are all easily available as commercial products. Among these, use of a nylon 6/66 copolymer and a blend thereof with nylon 6 is preferable from the viewpoint of a balance between gas barrier properties and fatigue durability. The compounding ratio of the butyl rubber (A) and the nylon resin (B) is not particularly limited, but the ratio (weight) of the rubber (A) / resin (B) is 55/45 to 95 / from the viewpoint of fatigue durability. 5 is preferable, and 60/40 to 85/15 is more preferable.

  The nylon resin (B) constituting the matrix phase of the elastomer composition of the present invention is a general plasticizer for nylon resin (D), for example, sulfonamides such as ethyltoluenesulfonamide, cyclohexyltoluenesulfonamide, and butylbenzenesulfonamide. Compounds, or octyl ester of p-oxybenzoic acid, dimethyl phthalate, triphenyl phosphate, glycerin, hexyl glycol, and the like, and butylbenzenesulfonamide is used as a particularly preferable plasticizer (D) from the viewpoint of compatibility. To preferred. The blending amount of the plasticizer (D) is not particularly limited, but it is preferably 10 to 40% by weight, more preferably 20 to 35% by weight based on the weight of the nylon resin (B).

  In the elastomer composition of the present invention, the modified polyolefin (E) is used as a compatibilizing agent for the butyl rubber (A) constituting the dispersed phase and the nylon resin (B) constituting the matrix phase, and the butyl rubber (A) and the nylon resin. It is preferable to mix at the time of kneading of (B). Examples of such a modified polyolefin include maleic anhydride-modified ethylene ethyl acrylate copolymer, ethylene propylene copolymer, ethylene butene copolymer, ethylene hexene copolymer, or ethylene octene copolymer anhydride maleate. it can. The blending amount of the modified polyolefin (E) is not particularly limited, but is preferably 1 to 15% by weight with respect to the weight of the butyl rubber (A) from the viewpoint of gas barrier properties and fatigue durability, and 5 to 12 More preferably, it is% by weight.

  During kneading of the butyl rubber (A) and the nylon resin (B) constituting the elastomer composition of the present invention, the butyl rubber (A) is dynamically cross-linked by blending the cross-linking agent (F). preferable. In particular, the cross-linking agent (F) and the butyl rubber (A) are kneaded first to obtain a rubber composition, and then kneaded with the nylon resin (B) to dynamically cross-link the butyl rubber (A) to an elastomer composition. It is preferable to produce a product. Here, “dynamic crosslinking” means that the resin and the rubber are mixed well and the rubber is crosslinked by adding a crosslinking agent in a state where the mixing is continued.

  Examples of the crosslinking agent (F) used in a preferred embodiment of the present invention include zinc oxide, magnesium oxide, methylolphenol, and the like, and these are known commercially available compounds that can be easily obtained by those skilled in the art. It can be done.

  In addition to the above-described components, the elastomer composition produced by the present invention includes other reinforcing agents (fillers) such as carbon black and silica, vulcanization or crosslinking agents, vulcanization or crosslinking accelerators, various oils, aging Various additives that are generally blended for tires such as inhibitors and plasticizers, and other rubber compositions can be blended, and these additives are kneaded into a composition by a general method, Can be used to vulcanize or crosslink. As long as the amount of these additives is not contrary to the object of the present invention, a conventional general amount can be used. Moreover, the method of manufacturing the inner liner of a pneumatic tire, for example using the elastomer composition of this invention can be based on the previous example.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further, it cannot be overemphasized that the scope of the present invention is not limited to these Examples.

Sample Preparation Method of Examples 1 to 5 The rubber (A) and the crosslinking agent (F) were kneaded at 100 ° C. for 2 minutes with a Banbury mixer (Kobe Steel) and then 100 ° C. with a rubber pelletizer (Moriyama Seisakusho). And processed into a pellet-like rubber composition. Next, using a twin-screw kneader (TEX44, Nippon Steel Works), the resin (B), titanium oxide (C) masterbatch and plasticizer (D) are first kneaded at 230 ° C. to obtain a resin composition, which is in a strand shape And then cut into pellets. Next, the rubber composition, the resin composition, and the modified polyolefin were kneaded at 230 ° C. with the biaxial kneader described above, extruded into a strand shape, and cut into a pellet shape. The produced pellets were processed into a 1 mm thick sheet at 230 ° C. by a T-die molding machine.

Sample Preparation Method of Comparative Example 1 The rubber (A) and the crosslinking agent (F) were kneaded for 2 minutes at 100 ° C. with a Banbury mixer (Kobe Steel) and then pelletized at 100 ° C. with a rubber pelletizer (Moriyama Seisakusho). Into a rubber composition. Next, using a twin-screw kneader (TEX44, Nippon Steel Works), the resin (B) and the plasticizer (D) are first mixed in the first kneading zone, and the rubber composition and the titanium oxide (C) master are mixed in the next kneading zone. The batch and modified polyolefin were added, kneaded at 230 ° C., extruded into strands, and cut into pellets. The produced pellets were processed into a 1 mm thick sheet at 230 ° C. by a T-die molding machine.

Sample Preparation Method of Comparative Example 2 Rubber (A) and crosslinking agent (F) were kneaded for 2 minutes at 100 ° C. with a Banbury mixer (Kobe Steel Works), and then pelleted at 100 ° C. with a rubber pelletizer (Moriyama Seisakusho). Into a rubber composition. Next, using a biaxial kneader (TEX44, Nippon Steel Works), first, the resin (B) and the plasticizer (D) were kneaded at 230 ° C. to obtain a resin composition, which was extruded into a strand shape and cut into a pellet shape. . Next, the rubber composition, the resin composition, the titanium oxide (C) masterbatch, and the modified polyolefin were kneaded at 230 ° C. with the above-described biaxial kneader, extruded into a strand shape, and cut into pellets. The produced pellets were processed into a 1 mm thick sheet at 230 ° C. by a T-die molding machine.

Sample Preparation Method of Comparative Example 3 The rubber (A) and the crosslinking agent (F) were kneaded for 2 minutes at 100 ° C. with a Banbury mixer (Kobe Steel) and then pelletized at 100 ° C. with a rubber pelletizer (Moriyama Seisakusho). Into a rubber composition. Next, using a biaxial kneader (TEX44, Nippon Steel Works), first, the resin (B) and the plasticizer (D) were kneaded at 230 ° C. to obtain a resin composition, which was extruded into a strand shape and cut into a pellet shape. . Next, the rubber composition, the resin composition, and the modified polyolefin were kneaded at 230 ° C. with the aforementioned biaxial kneader, extruded into a strand shape, and cut into a pellet shape to obtain a thermoplastic elastomer composition. Next, the thermoplastic elastomer composition and the titanium oxide (C) masterbatch were kneaded at 230 ° C. with a twin-screw kneader (TEX44, Nippon Steel), extruded into a strand, and cut into a pellet. The produced pellets were processed into a 1 mm thick sheet at 230 ° C. by a T-die molding machine.

Sample Preparation Method of Comparative Example 4 Rubber (A) and crosslinking agent (F) were kneaded at 100 ° C. for 2 minutes with a Banbury mixer (manufactured by Kobe Steel), and then pelletized at 100 ° C. with a rubber pelletizer (manufactured by Moriyama Seisakusho). The rubber composition was processed. Next, using a biaxial kneader (TEX44, Nippon Steel Works), first, the resin (B) and the plasticizer (D) were kneaded at 230 ° C. to obtain a resin composition, which was extruded into a strand shape and cut into a pellet shape. . Next, the rubber composition, the resin composition, and the modified polyolefin were kneaded at 230 ° C. with the aforementioned biaxial kneader, extruded into a strand shape, and cut into a pellet shape to obtain a thermoplastic elastomer composition. The prepared thermoplastic elastomer composition pellets and titanium oxide (C) masterbatch pellets were mixed well and placed in a T-die molding machine, and processed into a 1 mm thick sheet at 230 ° C.

Table I Footnote Br-IPMS; Exxpro MDX89-4 (Exxon Mobile Chemicals)
Br-IIR; Bromobutyl X2 (Bayer)
IIR; Exxon Butyl 268 (Exxon Mobile Chemicals)
PIB; Opanol B100 (BASF)
Zinc Hana; Zinc Hana No. 3 (Jodo Chemical)
Stearic acid; bead stearic acid (Japanese fats and oils)
Nylon 6,66; UBE nylon 5033B (Ube Industries)
Nylon 6; UBE nylon 1030B (Ube Industries)
Nylon 11; Rilsan BESNOTL (ARKEMA)
Nylon 66; UBE nylon 2026B (Ube Industries)
Titanium oxide master batch; PAM (F) 25529 White (Daiichi Seika Kogyo, nylon 6 / titanium oxide = 60/40 wt%)
BBSA; BM-4 (Daihachi Chemical Industry)
Carbon black; MA600 (Mitsubishi Chemical)
6PPD; SANTFLEX 6PPD (FLEXSYS)
HALS; Tinuvin 622LD (Ciba Specialty Chemicals)
UVA; Tinuvin 234 (Ciba Specialty Chemicals)
Mah-EEA; HPRAR201 (Mitsui DuPont Polychemical)
Mah-EPM; Toughmer MP0620 (Mitsui Chemicals)
Mah-EO; Exxcelor VA1840 (Exxon Mobile Chemicals)

Durability evaluation method Eight JIS No. 3 dumbbells were punched from a 1mm thick sheet and subjected to repeated strain up to 10 million times at a strain of 40%, -20 ° C and 6.7Hz with a constant strain tester (manufactured by Ueshima Seisakusho). It was. The number of ruptures of the dumbbell after the test was Weibull plotted, and the number of ruptures giving a 70% rupture rate was calculated as the fatigue life. The initial durability was tested as it was after the sheet was formed, and the fatigue life was measured.

SW (Sunshine Weather) Test Method Durability after SW was tested with a sunshine weather meter (made by Suga Test Instruments, using a carbon arc light source) at 63 ° C for 60 minutes under the conditions of rainfall for 12 minutes, followed by a constant strain test. The fatigue life was measured. The fatigue life passed 1 million times or more, and less than 1 million times was rejected. The results are shown in Table II and Table III.

Tire Evaluation Methods in Tables II and III The elastomer composition pellets produced by the production method in Table 1 were extruded into a 15-inch cylinder by inflation molding at 230 ° C. The extruded cylinder was cut in the circumferential direction to produce a tire inner liner member. Using this member, a tire of 195 / 65R15 was produced by vulcanization at 180 ° C. for 10 minutes.
After using 195 / 65R15 tires (rim 15 × 6JJ) and mounting each test tire on a rim size 15 × 6JJ rim, the diameter was 1707 mm under the conditions of air pressure 140 kPa, −20 ° C., load 6.1 kN. Was run at a speed of 80 km / h to a maximum travel distance of 1500 km, and the inner liner surface was observed. For new products, the produced tires were tested as they were, and for 6 months outdoor exposure, the produced tires were left outdoors for 6 months and then tested. Judgment is made by removing the tire from the rim after the test and observing the inner surface, and if the size of one crack on the inner liner is 10 mm or less and the total number of cracks is 10 or less, the size or number exceeds the specified value. It was rejected.

  According to the method of the present invention, even when an elastomer composition blended with butyl rubber (A) / nylon resin (B) is used as an inner liner for a tire, the tire is displayed outdoors for a long time at a store such as a store. Even so, it is possible to prevent the rubber from being deteriorated by ultraviolet rays, so that the rubber can be used without deteriorating its characteristics. In addition, there is an example in which a release agent containing carbon black is applied to the inner surface of the tire for the convenience of manufacturing the tire. In this case, the presence of the release agent on the inner liner surface of the pneumatic tire causes the ultraviolet ray of rubber. Although degradation is prevented to some extent, according to the method of the present invention, ultraviolet degradation can be suppressed without using a carbon black-containing release agent, so that a stable characteristic is imparted to a pneumatic tire as an inner liner. be able to.

Claims (16)

  (I) Brominated product of isobutylene and paramethylstyrene copolymer rubber or (ii) Blend of at least one rubber selected from butyl rubber, halogenated butyl rubber and polyisobutylene rubber and brominated product of isobutylene and paramethylstyrene copolymer rubber Nylon resin (B) selected from at least one selected from nylon 11, nylon 6/66 copolymer, nylon 6 and nylon 66, or a blend thereof. An elastomer composition obtained by blending 2.5 to 8% by weight of titanium oxide (C) with respect to the weight of the nylon resin (B) in the matrix phase of a butyl rubber / nylon resin blend composition in which is a matrix phase. In the first stage, the resin (B) and titanium oxide (C) to be blended are all mixed in the first stage. Ndoshi, then the resulting blend and the rubber (A) and production method of the elastomer composition, which comprises kneading.   The method for producing an elastomer composition according to claim 1, wherein the butyl rubber (A) is a brominated product of isobutylene and paramethylstyrene copolymer rubber.   The method for producing an elastomer composition according to claim 1 or 2, wherein the nylon resin (B) is a nylon 6/66 copolymer.   The method for producing an elastomer composition according to claim 1 or 2, wherein the nylon resin (B) is a blend of nylon 6/66 copolymer and nylon 6.   The manufacturing method of the elastomer composition of any one of Claims 1-4 which mix | blended the plasticizer (D) for the said nylon resin (B).   The method for producing an elastomer composition according to claim 5, wherein the amount of the plasticizer (D) is 10 to 40% by weight based on the weight of the nylon resin (B).   The method for producing an elastomer composition according to claim 5, wherein a blending amount of the plasticizer (D) is 20 to 35% by weight with respect to a weight of the nylon resin (B).   The method for producing an elastomer composition according to any one of claims 5 to 7, wherein the plasticizer (D) is butylbenzenesulfonamide.   The modified polyolefin (E) is blended at the time of kneading the butyl rubber (A) and the nylon resin (B) as a compatibilizer between the butyl rubber (A) and the nylon resin (B). A process for producing the elastomer composition according to claim 1.   The method for producing an elastomer composition according to claim 9, wherein the amount of the modified polyolefin (E) is 1 to 15% by weight based on the weight of the butyl rubber (A).   The method for producing an elastomer composition according to claim 9, wherein the amount of the modified polyolefin (E) is 5 to 12% by weight based on the weight of the butyl rubber (A).   The method for producing an elastomer composition according to any one of claims 9 to 11, wherein the modified polyolefin (E) is a maleic anhydride-modified ethylene ethyl acrylate copolymer.   The elastomer according to any one of claims 9 to 11, wherein the modified polyolefin (E) is an anhydrous maleated product of an ethylene propylene copolymer, an ethylene butene copolymer, an ethylene hexene copolymer or an ethylene octene copolymer. A method for producing the composition. The elastomer composition manufactured by the method according to any one of claims 1 to 13, wherein the butyl-based rubber is blended with the butyl rubber (A) and the nylon resin (B) by blending the crosslinking agent (F). A method for producing an elastomer composition, wherein rubber (A) is dynamically crosslinked.   The cross-linking agent (F) and the butyl rubber (A) are kneaded first to obtain a rubber composition, and then kneaded with the nylon resin (B) to dynamically cross-link the butyl rubber (A). The manufacturing method of the elastomer composition as described in any one of.   The pneumatic tire which used the elastomer composition manufactured by the method of any one of Claims 1-15 for the inner liner.