Bladder and tire producing method

• US 20030122284A1
• Filed: 11/01/2002
• Published: 07/03/2003
• Est. Priority Date: 11/02/2001
• Status: Active Grant

• Current Assignee: Klaus Schmidt, Teijin Limited
• Original Assignee: Teijin Limited
• Inventors: Mori, Hiroyuki, Takayama, Yozaburo, Kogishi, Takayuki, Fujiwara, Naoya, Yoshikawa, Eiichiro, Okada, Kazuto, Mitamura, Hisashi, Fujisawa, Kazuhisa
• Granted Patent: US 6,824,724 B2
• Time in Patent Office: Days
• US Class Current: 264/501
• CPC Class Codes: B29C 2043/3649 Inflatable bladders using gas or fluid and related details
• CPC Class Codes: B29C 33/505 cores or mandrels, e.g. inflatable B29C33/0016 takes precedence; for winding and joining B29C53/824; for supporting articles during joining B29C66/634; flexible cores for vulcanizing tyres B29D30/0654
• CPC Class Codes: B29C 43/104 the mould cavity lying totally outside the axis of symmetry, e.g. toroidal moulds
• CPC Class Codes: B29C 43/3642 Bags, bleeder sheets or cauls for isostatic pressing
• CPC Class Codes: B29D 2030/0655 Constructional or chemical features of the flexible cores
• CPC Class Codes: B29D 30/0601 Vulcanising tyres; Vulcanising presses for tyres
• CPC Class Codes: B29D 30/0654 Flexible cores therefor, e.g. bladders, bags, membranes, diaphragms elastic cores or mandrels for shaping of plastics B29C33/505; bags for isostatic pressing in compression moulding B29C43/12, B29C43/3642
• CPC Class Codes: B29L 2030/00 Pneumatic or solid tyres or parts thereof conveyor belts B29L2031/7092; drive belts B29L2031/7094; fourdrinier belts B29L2031/733

Abstract

An object of the present invention is to provide a bladder which is unlikely to have a shapal variation along the inner wall surface of the tire and can satisfactorily extend along the inner wall surface of the tire. An inventive bladder is used to press the inner wall surface of the tire by a pressurized heating medium during the vulcanization of a green tire and is comprised of a fabric layer (purl stitched fabric layer 12) and rubber layers (silicone rubber layers 11, 13) placed one over another. Elongation rates of the fabric layer in warp direction and in weft direction both exceed 15% and satisfy: 0.4≦elongation rate in weft direction/elongation rate in warp direction≦6.0. Since the fabric layer has good extensibility, it can elongate with the rubber layers.

Claims

1. A bladder used to press the inner wall surface of a tire by means of a pressurized heating medium during the vulcanization of a green tire, comprising at least one rubber layer and at least one fabric layer, wherein elongation rates of the fabric layer in warp direction and in weft direction both exceed 15% and satisfy following equation (1):

0.4≦

elongation rate in weft direction/elongation rate in warp direction≦

6.0 

 

(1).

2. A bladder according to claim 1, wherein the elongation rates of the fabric layer in warp direction and in weft direction both exceeds 25%.

3. A bladder according to claim 1, wherein the fabric layer satisfies following equation (2):

0.5≦

elongation rate in weft direction/elongation rate in warp direction≦

1.7 

 

(2).

4. A bladder according to claim 1, wherein the fabric layer is made of a knitted fabric.

5. A bladder according to claim 4, wherein the knitted fabric is made by circular knitted stitches.

6. A bladder according to claim 4, wherein the knitted fabric is a purl stitched fabric.

7. A bladder according to claim 4, wherein the stitch density of the knitted fabric is 5 to 25 courses/2.54 cm and 5 to 25 wales/2.54 cm.

8. A bladder according to claim 1, wherein the fabric layer is made from high-strength fibers of 17 cN/dtex or higher.

9. A bladder according to claim 8, wherein the fabric layer is made from spun yarns made of high-strength fibers, false twist yarns made of high-strength fibers by a draft zone system spinning method or composite yarns of these yarns.

10. A bladder according to claim 8, wherein the high-strength fibers are aramid fibers.

11. A bladder according to claim 10, wherein the aramid fibers are copolyparaphenylen·

3,4′

-oxydiphenylene terephthalamide fibers.

12. A bladder according to claim 1, wherein the bladder has a three-layer structure in which rubber layers are provided on both surfaces of the fabric layer.

13. A bladder according to claim 1, wherein the bladder has a two-layer structure in which a rubber layer is provided on one surface of the fabric layer.

14. A bladder according to claim 1, wherein the fabric layer is embedded in the rubber layer.

15. A tire producing method, comprising the steps of:

placing a bladder inside a green tire set in a mold, and

supplying a pressurized heating medium to the inside of the bladder to vulcanize the green tire while pressing it against the inner wall surface of the mold,

wherein the bladder comprises at least one rubber layer and at least one fabric layer, and elongation rates of the fabric layer in warp direction and in weft direction both exceed 15% and satisfy following equation (1);

0.4≦

elongation rate in weft direction/elongation rate in warp direction≦

6.0 

 

(1).