Method for vulcanizing an elastomeric product including alternate heating and pressurizing steps

• US 5,240,669 A
• Filed: 12/12/1990
• Issued: 08/31/1993
• Est. Priority Date: 12/28/1989
• Status: Expired due to Fees

• Current Assignee: Sumitomo Rubber Industries Limited
• Original Assignee: Sumitomo Rubber Industries Limited
• Inventors: Kobayashi, Michihito
• Primary Examiner(s): Woo, Jay H.
• Assistant Examiner(s): Davis, Robert B.
• Application Number:
  US07/626,067
• Time in Patent Office: 993 Days
• Field of Search: 264/315, 264/326, 264/40.3, 264/40.6, 264/85, 264/347, 264/501, 264/347, 264/236, 425/29, 425/42, 425/34, 425/42
• US Class Current: 264/315
• CPC Class Codes: B29D 2030/0667 Circulating the fluids, e.g. introducing and removing them into and from the moulds; devices therefor
• CPC Class Codes: B29D 2030/0673 the vulcanizing fluids being combinations of different kinds of fluids, e.g. steam and nitrogen
• CPC Class Codes: B29D 2030/0675 Controlling the vulcanization processes
• CPC Class Codes: B29D 30/0662 Accessories, details or auxiliary operations

Abstract

A method for vulcanizing an elastomeric product placed in a vulcanizing apparatus includes one step of supplying heating medium into the elastomeric product and another step of supplying pressurizing medium into the elastomeric product at a higher pressure than the heating medium, the two steps being performed one after another at least two times. This method can produce an elastomeric product having no bareness without increasing the vulcanizing time.

Claims

1. A process for vulcanizing an elastomeric product comprising the steps of:

(A) placing an elastomeric product into a mold;

(B) applying, sequentially and alternately, at least two each of a heating step and a pressurizing step to the elastomeric product in order to effect vulcanization; and

(C) removing the vulcanized elastomeric product from said mold;

wherein said heating steps are carried out at a lower pressure than said pressurizing steps and wherein a duration of heating in said first stage heating is greater than a duration of heating in said second stage heating and a duration of the first stage pressurizing is less than a duration of the second stage pressurizing.

2. The process according to claim 1, wherein the first of said at least two heating steps is carried out until the elastomeric product is at most 15% cured.

3. The process according to claim 1, wherein the pressurizing step that is applied subsequently to a first heating step is carried out until said elastomeric product is no longer fluid-like.

4. The process according to claim 1, wherein the pressurizing step that is applied subsequently to a first heating step is carried out until the air trapped in the elastomeric product and between the elastomeric product and the mold is eliminated.

5. The process according to claim 1, wherein said heating and pressurizing steps of said step B comprise:

(1) a first pressurizing step;

(2) a first heating step;

(3) a second pressurizing step;

(4) a second heating step; and

(5) a third pressurizing step.

6. The process according to claim 1, wherein said mold includes a bladder.

7. The process according to claim 6, wherein said heating steps are carried out by supplying a heating medium into said bladder.

8. The process according to claim 7, wherein said heating medium comprises steam.

9. The process according to claim 6, wherein said pressurizing steps are carried out by supplying a pressurizing medium into said bladder.

10. The process according to claim 9, wherein said pressurizing medium comprises a gas.

11. A process for vulcanizing an elastomeric product comprising the steps of:

(A) placing an elastomeric product into a mold;

(B) applying, sequentially and alternately, at least two each of a heating step and a pressurizing step to the elastomeric product in order to effect vulcanization; and

(C) removing the vulcanized elastomeric product from said mold;

wherein said heating steps are carried out at a lower pressure than said pressurizing steps and wherein said two heating steps are performed at the same pressure, said two pressurizing steps are performed at the same pressure and a first one of said pressurizing steps is performed for a duration necessary to vulcanize said elastomeric product.

12. The process according to claim 11, wherein the first of said at least two heating steps is carried out until the elastomeric product is at most 15% cured.

13. The process according to claim 11, wherein the pressurizing step that is applied subsequently to a first heating step is carried out until said elastomeric product is no longer fluid-like.

14. The process according to claim 11, wherein the pressurizing step that is applied subsequently to a first heating step is carried out until the air trapped in the elastomeric product and between the elastomeric product and the mold is eliminated.

15. The process according to claim 11, wherein said heating and pressurizing steps of said step B comprise:

(1) a first pressurizing step;

(2) a first heating step;

(3) a second pressurizing step;

(4) a second heating step; and

(5) a third pressurizing step.

16. The process according to claim 11, wherein said mold includes a bladder.

17. The process according to claim 16, wherein said heating steps are carried out by supplying a heating medium into said bladder.

18. The process according to claim 17, wherein said heating medium comprises steam.

19. The process according to claim 16, wherein said pressurizing steps are carried out by supplying a pressurizing medium into said bladder.

20. The process according to claim 19, wherein said pressurizing medium comprises a gas.

21. The process according to claim 20, wherein said gas comprises at least one gas selected from the group consisting of nitrogen gas and combustion gas.