Process for preparing a composite tubular article consisting of a vulcanized elastomer used in combination with a thermoplastic containing polyamide blocks especially petrol pipe

• US 5,643,526 A
• Filed: 06/02/1995
• Issued: 07/01/1997
• Est. Priority Date: 01/13/1993
• Status: Expired due to Fees

• Current Assignee: Elf Atochem S.A.
• Original Assignee: Elf Atochem S.A.
• Inventors: Dousson, Christian, Nawrot, Serge, Hert, Marius
• Primary Examiner(s): THURLOW, JEFFERY
• Application Number:
  US08/458,789
• Time in Patent Office: 760 Days
• Field of Search: 264/171.12, 264/171.26-236, 264/347, 264/476, 156/307.7
• US Class Current: 264/476
• CPC Class Codes: B29C 48/00 Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor extrusion blow-moulding B29C49/04
• 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 48/151 Coating hollow articles
• CPC Class Codes: B29C 48/21 the layers being joined at their surfaces
• CPC Class Codes: B29K 2019/00 Use of rubber not provided for in a single one of main groups B29K2007/00 - B29K2011/00, as moulding material
• CPC Class Codes: B29K 2077/00 Use of PA, i.e. polyamides, e.g. polyesteramides or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2105/24 crosslinked or vulcanised
• CPC Class Codes: B29L 2023/005 Hoses, i.e. flexible
• CPC Class Codes: B32B 1/08 Tubular products
• CPC Class Codes: B32B 2038/0076 Curing, vulcanising, cross-linking
• CPC Class Codes: B32B 2270/00 Resin or rubber layer containing a blend of at least two different polymers
• CPC Class Codes: B32B 2305/72 Cured, e.g. vulcanised, cross-linked
• CPC Class Codes: B32B 2309/02 Temperature
• CPC Class Codes: B32B 25/08 of synthetic resin
• CPC Class Codes: B32B 25/14 comprising synthetic rubber copolymers B32B25/18 and B32B25/20 take precedence
• CPC Class Codes: B32B 27/304 comprising vinyl halide (co)polymers, e.g. PVC, PVDC, PVF, PVDF
• CPC Class Codes: B32B 27/32 comprising polyolefins comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30
• CPC Class Codes: B32B 27/34 comprising polyamides
• CPC Class Codes: C08J 5/12 Bonding of a preformed macromolecular material to the same or other solid material such as metal, glass, leather, e.g. using adhesives
• CPC Class Codes: F16L 11/04 made of rubber or flexible plastics
• CPC Class Codes: F16L 2011/047 : with a diffusion barrier layer
• CPC Class Codes: Y10T 428/1393 : Multilayer [continuous layer]
• CPC Class Codes: Y10T 428/3154 : Of fluorinated addition polymer from unsaturated monomers
• CPC Class Codes: Y10T 428/31739 : Nylon type
• CPC Class Codes: Y10T 428/31761 : Next to aldehyde or ketone condensation product
• CPC Class Codes: Y10T 428/31859 : Next to an aldehyde or ketone condensation product

Abstract

The invention relates to a process for preparing a composite tubular article consisting of a vulcanized elastomer containing carboxylic acid or dicarboxylic acid anhydride functional groups, which is used in combination with a thermoplastic elastomer containing polyamide blocks. The composite tubular article is prepared such that it consists of an inner layer of thermoplastic elastomer containing polyamide blocks sheathed by extrusion at an appropriate temperature with an elastomeric composition comprising a synthetic or natural elastomer containing carboxylic acid or dicarboxylic acid anhydride functional groups, a crosslinking system and optionally various adjuvants and fillers. Optionally, an innermost layer consisting of a thermoplastic with good liquid-barrier properties is present. The composite tubular article obtained is vulcanized, preferably at a temperature of between -5° C. and +30° C. in relation to the Vicat point of the said thermoplastic elastomer containing polyamide blocks. This process produces composite tubular articles exhibiting excellent properties, particularly of flexibility and of peel strength of the outer layer. The invention also relates to a process for preparing petrol pipes consisting of such articles in which the inner face of the thermoplastic tube is coated with a polymer for protection against liquids and preferably against fuels.

Claims

1. A process for the preparation of a composite tubular article consisting of an outer sheath of a vulcanized elastomer containing carboxylic acid or dicarboxcylic acid anhydride functional groups, used directly in combination with a tube of thermoplastic elastomer containing polyamide blocks having a melting point of between 120°

C. and 210°

C., the said article exhibiting a high peel strength of the vulcanized elastomer sheath when subjected to a separating stress, preferably higher than 2 daN/cm, comprising (a) sheathing a tubular thermoplastic elastomer containing polyamide blocks by extrusion at a temperature of between 50°

C. and 120°

C., with a vulcanizable elastomeric composition comprising a carboxylic acid or dicarboxcylic acid anhydride functional groups and a crosslinking system and optionally various adjuvants and fillers, and (b) vulcanizing said sheath, wherein said vulcanizing is completed in 15 minutes or less at a temperature between -5°

C. and +30°

C. relative to a Vicat point of said thermoplastic elastomer containing polyamide blocks.

2. The process for the preparation of a composite tubular article of claim 1, wherein said vulcanizable elastomeric composition is extruded into a sheathing die in which there is present a thermoplastic tube.

3. The process for the preparation of a composite tubular article of claim 1, wherein said vulcanizing is completed in a vulcanization autoclave for rubber that uses hot air and infrared to achieve vulcanization.

4. The process for the preparation of a composite tubular article of claim 1, wherein the tubular thermoplastic elastomer containing polyamide blocks further comprises fillers between 5 and 100 parts by weight per 100 parts of elastomers.

5. The process for the preparation of a composite tubular article of claim 1, wherein the vulcanization temperature is about at the Vicat point of the thermoplastic elastomer containing polyamide blocks.

6. The process for the preparation of a composite tubular article of claim 1, wherein said vulcanizing has a t₉₀ of 15 minutes or less.

7. The process for the preparation of a composite tubular article of claim 1, wherein said vulcanizing has a t₉₀ between 5 and 10 minutes.

8. The process for the preparation of a composite tubular article of claim 1, wherein said vulcanizing yields a torque increase of 0.3 Nm in between 4 and 6 minutes.

9. The process for the preparation of a composite tubular article of claim 1, wherein said tubular thermoplastic elastomer containing polyamide blocks further comprises an inner protective layer of polyamide with a melting point higher than 220°

C.

10. The process for the preparation of a composite tubular article of claim 9, wherein said inner protective layer of polyamide is a polyamide 6 or polyamide 66.

11. The process for the preparation of a composite tubular article of claim 1, wherein said vulcanization is carried out continuously by placing a UHF oven in line with a sheathing extruder.

12. The process for the preparation of a composite tubular article of claim 1, wherein said article exhibits a peel strength higher than 2 daN/cm.