Elastomer composition, method for producing same, and pneumatic tire using same
An elastomer composition, having an excellent flexibility and low temperature durability, a method for producing the same and a pneumatic tire using the same are provided. An elastomer composition (C) comprising 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 (B) satisfy the following formula (I): φ d/φm>ηd/ηm (I) wherein 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)), a method for producing the same and a pneumatic tire using the same.
1. A pneumatic tire having an inner liner in the form of a sheet comprising an elastomer composition (C) having no thermoplasticity which comprises a matrix of at least one thermoplastic resin (A) 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 in which a dispersed phase of at least one elastomer component (B) selected from the group consisting of a bromide of an isoprene-paramethyl styrene copolymer, a maleic anhydride-modified ethylene-α-olefin copolymer, butyl rubber and halogenated butyl rubber is finely dispersed to form an island-in-sea structure, wherein volume ratios of the thermoplastic resin (A) and the elastomer component (B) 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).
2. A pneumatic tire as claimed in claim 1 , wherein the volume ratio of elastomer component (B) is 55 to 95.
3. A pneumatic tire as claimed in claim 1 , wherein the at least one thermoplastic resin (A) is Nylon 6 or Nylon 6/66.
4. A pneumatic tire as claimed in claim 1 , wherein the at least one elastomer component (B) is at least one elastomer is a bromide of isoprene-paramethyl styrene copolymer or a maleic anhydride-modified ethylene-α-olefin.
5. A pneumatic tire as claimed in claim 1 , wherein the inner liner in the form of a sheet is manufactured by a method comprising the steps of:
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 ml/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) to thereby form a thermoplastic elastomer composition (E);
forming a sheet from the thermoplastic elastomer composition (E); and
removing the plasticizer (D) by evaporation, extraction or migration.