Elastomer composition, method for producing same and pneumatic tire using same

1. A method for producing an elastomer

composition (C) having no thermoplasticity which comprises a matrix of a thermoplastic resin (A) in which a dispersed phase of an elastomer component (B) is finely dispersed to form an island-in-sea structure, wherein volume ratios of the thermoplastic resin (A) and the elastomer component ( 3 ) satisfy the following formula (I):

φ d/φm>ηd/ηm   (I)

where φd and ηd, respectively, indicate a volume ratio and a melt viscosity of the elastomer component (B) and φm and ηm, respectively, indicate a volume ratio and a melt viscosity of the thermoplastic resin (A), said method comprising:

mixing and shaping a thermoplastic

resin (A), an elastomer component (B) and a plasticizer (D) in a ratio satisfying the following formulae (II)

and (III):

φ d /(φ m+φ 1)×(η n/ηd )<1  (II)

η ml/ηd= 0.8-1.2  (III)

wherein φd and ηd, respectively, indicate a volume ratio and a viscosity of the elastomer component (B), φm indicates a volume ratio of the thermoplastic resin (A), φ1 indicates a volume ratio of the plasticizer (D) and ηml indicates a melt viscosity of a mixture of the thermoplastic resin (A) and the plasticizer (D); and, then,

removing the plasticizer (D) by evaporation, extraction or migration.

2. A method for producing an elastomer composition (C) according to claim 1 , wherein the plasticizer (D) is alkylbenzene sulfonamide.

3. A method as claimed in claim 1 , wherein the thermoplastic resin (A) is at least one thermoplastic resin selected from the group consisting of Nylon 6, Nylon 6/66 copolymer, Nylon 11, Nylon 12, a Nylon 6/10 copolymer and a Nylon 6/12 copolymer.

4. A method as claimed in claim 1 , wherein the elastomer component (B) is at least one elastomer selected from the group consisting of a bromide of an isoprene-paramethyl styrene copolymer, a maleic anhydride-modified ethylene-α-olefin copolymer, butyl rubber, halogenated butyl rubber and polyisoprene rubber.