Method for manufacturing bladder for use in manufacturing tires

1. A method for manufacturing a bladder for use in manufacturing tires that comprises a surface-modified rubber layer on an outer surface side of a base rubber layer, comprising the steps of:

forming an uncross-linked body of the surface-modified rubber layer by molding a rubber composition including a modified butyl rubber composition (A) or (B) and an organic peroxide and applying a siloxane compound having a (meth)acryloyl group to a surface of this rubber molded body;

wherein the modified butyl rubber composition (A) comprises a modified butyl rubber ( 1 ) formed by reacting with butyl rubber a compound (a) having a nitroxide free radical in a molecule that is stable at ambient temperature in the presence of oxygen, a radical initiator (b), and a radical polymeric monomer (c) having at least difunctionality; and the modified butyl rubber composition (B) is formed by compounding the monomer (c) with a modified butyl rubber ( 2 ) formed by reacting the compound (a) and the radical initiator (b) with butyl rubber;

forming the base rubber layer from an unvulcanized body or vulcanized body formed from a rubber composition different than the modified butyl rubber compositions (A) and (B);

laminating the uncross-linked body of the surface-modified rubber layer on the outer surface side of the base rubber layer; and

heat treating.

2. The method for manufacturing a bladder for use in manufacturing tires according to claim 1 , wherein the siloxane compound having a (meth)acryloyl group is at least one selected from organopolysiloxane compounds expressed by the following formulas (1), (2), or (3):

(wherein R 1 is a polyalkylene glycol or alkyl group, R 2 is hydrogen or a methyl group; and m and n are integers selected such that a number average molecular weight is from 1,000 to 20,000, and a ratio m:n satisfies 98:2 to 90:10);

(wherein R 3 is a hydrogen or a methyl group; R 4 is an alkyl group or an alkylene group; and p is an integer selected such that a number average molecular weight is from 100 to 20,000);

(wherein R 3 is hydrogen or a methyl group, R 4 and R 5 independently are alkyl groups or alkylene groups, and p is an integer selected such that a number average molecular weight is from 100 to 20,000).

3. The method for manufacturing a bladder for use in manufacturing tires according to claim 2 , wherein a number of carbon atoms in R 1 is from 4 to 30; and a number of carbon atoms in each of R 4 and R 5 is from 1 to 30.

4. The method for manufacturing a bladder for use in manufacturing tires according to claim 1 , wherein the radical polymeric monomer (c) having at least difunctionality and a radical polymeric monomer (d) having an alkoxysilyl group are simultaneously reacted or compounded.

5. The method for manufacturing a bladder for use in manufacturing tires according to claim 1 , wherein the base rubber layer comprises a base bladder that is formed by vulcanization molding a butyl rubber composition.

6. The method for manufacturing a bladder for use in manufacturing tires according to claim 5 , wherein after laminating the uncross-linked body of the surface-modified rubber layer on the outer surface side of the base bladder, this laminate is heat treated in a mold.

7. The method for manufacturing a bladder for use in manufacturing tires according to claim 1 , wherein the base rubber layer comprises a butyl rubber composition having at least one of butyl rubber and halogenated butyl rubber as a main component.

8. The method for manufacturing a bladder for use in manufacturing tires according to claim 1 , wherein the base rubber layer comprises from 30 to 80 parts by weight of carbon black compounded per 100 parts by weight of a rubber component of the base rubber layer.

9. The method for manufacturing a bladder for use in manufacturing tires according to claim 1 , wherein the base rubber layer comprises from 40 to 70 parts by weight of carbon black compounded per 100 parts by weight of a rubber component of the base rubber layer.

10. The method for manufacturing a bladder for use in manufacturing tires according to claim 1 , wherein an added amount of the compound (a) is from 0.001 to 0.5 mol, per 100 g of the butyl rubber.

11. The method for manufacturing a bladder for use in manufacturing tires according to claim 1 , wherein an added amount of the compound (a) is from 0.005 to 0.1 mol, per 100 g of the butyl rubber.

12. The method for manufacturing a bladder for use in manufacturing tires according to claim 1 , wherein an added amount of the radical initiator (b) is from 0.001 to 0.5 mol, per 100 g of the butyl rubber.

13. The method for manufacturing a bladder for use in manufacturing tires according to claim 1 , wherein an added amount of the radical initiator (b) is from 0.005 to 0.2 mol, per 100 g of the butyl rubber.

14. The method for manufacturing a bladder for use in manufacturing tires according to claim 4 , wherein the monomer (d) is in a hydrolyzed and condensed form.

15. The method for manufacturing a bladder for use in manufacturing tires according to claim 14 , wherein the monomer (d) is expressed by the following formula:

Si(OR 7 ) 4-n (R 6 -A) n

where R 6 and R 7 independently are hydrocarbon groups; R 7 contains an ether bond; A is a radical polymeric group; n is an integer from 1 to 3; and when n is 2 or 3, each of R 6 , R 7 , and A groups are different groups.

16. The method for manufacturing a bladder for use in manufacturing tires according to claim 14 , wherein an added amount of the monomer (d) is from 0.0001 to 0.5 mol, per 100 g of the butyl rubber.

17. The method for manufacturing a bladder for use in manufacturing tires according to claim 14 , further comprising preparing the modified butyl rubber composition (A) or (B) by:

heating a pre-blended mixture of the butyl rubber, the compound (a) and the radical initiator (b) at a temperature from 150 to 220° C. in a nitrogen-substituted sealed kneader until reaction occurs for the modified butyl rubber composition (B); or

temporarily reducing the temperature, adding the monomer (c) or the monomers (c) and (d) to the modified butyl rubber ( 2 ), repeating nitrogen substitution, and heating at a temperature from 120 to 220° C. until reaction occurs for the modified butyl rubber composition (A).

18. The method for manufacturing a bladder for use in manufacturing tires according to claim 1 , wherein an added amount of the organic peroxide is from 0.05 to 15 parts by weight per 100 weight parts of the rubber composition containing the modified butyl rubber ( 1 ) and ( 2 ).

19. The method for manufacturing a bladder for use in manufacturing tires according to claim 1 , wherein an added amount of the modified butyl rubbers ( 1 ) and ( 2 ) is at least 5 weight %.

20. A bladder for use in manufacturing tires manufactured according to the manufacturing method of claim 1 .