Flexible tube for endoscope, material used for producing outer cover of the flexible tube, and production method of the flexible tube

• US 6,599,239 B2
• Filed: 12/13/2000
• Issued: 07/29/2003
• Est. Priority Date: 12/13/1999
• Status: Active Grant

• Current Assignee: Hoya Corporation
• Original Assignee: Pentax Corporation (Hoya Corporation)
• Inventors: Ueki, Kensaku, Hayakawa, Shinji
• Primary Examiner(s): Walberg, Teresa
• Assistant Examiner(s): Fastovsky, Leonid M
• Application Number:
  US09/734,928
• Publication Number:
  US 20010007917A1
• Time in Patent Office: 958 Days
• Field of Search: 600/139, 600/140, 600/121, 604/282, 425/125, 523/211
• US Class Current: 600/139
• CPC Class Codes: A61B 1/00071 Insertion part of the endoscope body A61B1/0055 takes precedence
• CPC Class Codes: A61B 1/005 Flexible endoscopes
• CPC Class Codes: B29C 48/09 Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels
• CPC Class Codes: B29C 48/34 Cross-head annular extrusion nozzles, i.e. for simultaneously receiving moulding material and the preform to be coated
• CPC Class Codes: G02B 23/2476 Non-optical details, e.g. housings, mountings, supports

Abstract

A flexible tube for an endoscope includes a flexible elongated structural body and an outer cover provided over the elongated structural body. The outer cover is made of a material which contains polyurethane elastomer and polyester elastomer, in which compounding ratio of the polyurethane elastomer and the polyester elastomer in the material is 0.03-0.3 parts by weight of the polyester elastomer per 1 part by weight of the polyurethane elastomer. This flexible tube has excellent flexibility as well as various excellent properties such as chemical resistance, heat resistance and weather resistance.

Claims

1. A flexible tube for an endoscope comprising:

a flexible elongated structural body; and

an outer cover provided over the elongated structural body, the outer cover comprising polyurethane elastomer and polyester elastomer in a compounding ratio of 1 part by weight of the polyurethane per 0.03-0.2 parts by weight of the polyester.

2. The flexible tube of claim 1, comprising a compounding ratio of 1 part by weight of the polyurethane per 0.03-0.15 parts by weight of the polyester.

3. The flexible tube of claim 1, wherein the weight average molecular weight of the polyester elastomer lies within the range of 10,000-50,000.

4. The flexible tube of claim 1, wherein the polyurethane elastomer and the polyester elastomer are uniformly mixed.

5. A material used for producing an outer cover of a flexible tube for an endoscope, the material comprising polyurethane elastomer and polyester elastomer in a compounding ratio of 1 part by weight of the polyurethane per 0.03-0.2 parts by weight of the polyester.

6. The material of claim 5, comprising a compounding ratio of 1 part by weight of the polyurethane per 0.03-0.15 parts by weight of the polyester.

7. The material of claim 5, wherein the weight average molecular weight of the polyester elastomer lies within the range of 10,000-50,000.

8. The material of claim 5 wherein the polyurethane elastomer and the polyester elastomer are uniformly mixed.

9. A method of producing a flexible tube for an endoscope comprising:

preparing a material comprising polyurethane elastomer and polyester elastomer in a ratio of 1 part by weight of the polyurethane elastomer to 0.03-0.2 parts by weight of the polyester elastomer;

heating the material to such an extent that the material is melted or softened; and

molding the material onto a flexible elongated structural body to form an outer cover of the flexible tube in an elongated tubular form.

10. The method of claim 9, wherein the material prepared comprises polyurethane elastomer and polyester elastomer in a ratio of 1 part by weight of the polyurethane elastomer to 0.03-0.15 parts by weight of the polyester elastomer.

11. The method of claim 9, wherein the molding comprises extrusion molding.

12. The method of claim 9, wherein before the molding the temperature of the material is held at 140-230°

C.

13. The method of claim 9, wherein before the molding, the viscosity of the material lies within the range of 1.0×

10²-1.0×

10⁷ ps.

14. The method of claim 9, wherein the weight average molecular weight of the polyester elastomer lies within the range of 10,000-50,000.

15. The method of claim 9, wherein the preparing comprises stirring the material so that the polyurethane elastomer and the polyester elastomer are uniformly mixed.

16. The method of claim 15, wherein the preparing comprises pouring the material into a cylinder provided with a mixing screw, and stirring the material with the mixing screw under heated condition.

17. The method of claim 16, wherein the stirring comprises rotating the cylinder at a rotation speed of 2 to 30 rpm.

18. The method of claim 16, wherein the stirring comprises rotation speed control of the mixing screw comprising switching a rotation speed mode between at least two modes having different rotation speeds.

19. The method of claim 18, wherein the rotation speed mode of the mixing screw is switched at least two times per minute.

20. The method of claim 18, wherein the at least two modes having different rotation speeds have a difference of at least 5 rpm.