Pneumatic tire
In the pneumatic tire including a sealant layer containing an adhesive sealant on an inner surface of a tread portion, when a thickness of the sealant layer at 0° C. is G 0 , a thickness of the sealant layer at 50° C. is G 50 , a width of the sealant layer at 0° C. is W 0 , and a width of the sealant layer at 50° C. is W 50 , a rate of change R G of thickness expressed by R G =(|G 50 −G 0 |/G 0 )×100 is set to 3% or less, and a rate of change R W of width expressed by R W =(|W 50 −W 0 |/W 0 )×100 is set to 3% or less.
1 . A pneumatic tire comprising: a tread portion extending in a tire circumferential direction and having an annular shape, a pair of sidewall portions disposed on both sides of the tread portion, and a pair of bead portions disposed on an inner side in a tire radial direction of the sidewall portions, a sealant layer containing an adhesive sealant being provided at least on an inner surface of the tread portion and an auxiliary sheet only partially covering a surface of the sealant layer,
when a thickness of the sealant layer at 0° C. is G 0 , a thickness of the sealant layer at 50° C. is G 50 , a width of the sealant layer at 0° C. is W 0 , and a width of the sealant layer at 50° C. is W 50 , a rate of change R G of thickness expressed by Equation (1) being 3% or less, and a rate of change R W of width expressed by Equation (2) being 3% or less:
R G =(| G 50 −G 0 |/G 0 )×100 (1)
R W =(| W 50 −W 0 |/W 0 )×100 (2); wherein
the auxiliary sheet and the adhesive sealant collectively forming an innermost surface on a tire cavity side of the pneumatic tire at all points along a width and a circumference of the tire where the adhesive sealant is provided,
the adhesive sealant contains a crosslinking agent, an organic peroxide and a crosslinking aid, and the crosslinking agent contains a sulfur component,
a mass ratio A/B of a blended amount A of the crosslinking agent to a blended amount B of the organic peroxide is in a range of 2.5/1 to 5/1, and
a blended amount of the crosslinking aid is from 0.1 parts by mass to 0.9 parts by mass per 100 parts by mass of a rubber component included in the adhesive sealant.
2 . The pneumatic tire according to claim 1 , wherein the adhesive sealant is crosslinked.
3 . The pneumatic tire according to claim 1 , wherein, in the adhesive sealant, a proportion A of a toluene insoluble component expressed by Equation (3) is from 30 mass % to 60 mass %:
A =( M 2/ M 1)×100 (3)
where M2 is a mass (in g) of a toluene insoluble component remained after the adhesive sealant is immersed in toluene and allowed to stand still for one week, and M1 is an initial mass (in g) before the adhesive sealant is immersed in toluene.
4 . The pneumatic tire according to claim 1 , wherein a rubber component constituting the adhesive sealant contains a butyl rubber.
5 . The pneumatic tire according to claim 1 , further comprising an innerliner layer, the sealant layer being provided on a radially inner side of the innerliner layer at the tread portion.
6 . The pneumatic tire according to claim 1 , wherein the auxiliary sheet has a mesh form or a net form.
7 . The pneumatic tire according to claim 1 , wherein the auxiliary sheet covers at least 80% of a surface area of the adhesive sealant.
8 . The pneumatic tire according to claim 1 , wherein a ratio η 0 /η 50 of a viscosity η 0 (in kPa·s) of the adhesive sealant at 0° C. to a viscosity η 50 (in kPa·s) of the adhesive sealant at 50° C. is 6.0 or less.
9 . The pneumatic tire according to claim 8 , wherein the adhesive sealant is crosslinked.
10 . The pneumatic tire according to claim 9 , wherein, in the adhesive sealant, a proportion A of a toluene insoluble component expressed by Equation (3) is from 30 mass % to 60 mass %:
A =( M 2/ M 1)×100 (3)
where M2 is a mass (in g) of a toluene insoluble component remained after the adhesive sealant is immersed in toluene and allowed to stand still for one week, and M1 is an initial mass (in g) before the adhesive sealant is immersed in toluene.
11 . The pneumatic tire according to claim 10 , wherein a rubber component constituting the adhesive sealant contains a butyl rubber.