AU683267B2

AU683267B2 - Petrol supply tube

Info

Publication number: AU683267B2
Application number: AU69316/94A
Authority: AU
Inventors: Olivier Denizart; Serge Lorek; Daniel Siour
Original assignee: Elf Atochem SA
Current assignee: Arkema France SA
Priority date: 1993-06-03
Filing date: 1994-06-01
Publication date: 1997-11-06
Anticipated expiration: 2014-06-01
Also published as: AU6931694A; NO307271B1; DE69417447T2; EP0740754A1; JPH08511326A; FR2706011A1; WO1994029626A1; FI950466A0; DE69417447D1; EP0740754B1; FI107290B; ATE178130T1; KR100337680B1; FR2706011B1; FI950466A; DK0740754T3; CA2141590C; ES2130425T3; GR3030310T3; CA2141590A1

Abstract

Polyamide-based tube for supplying petrol, especially to engines, and characterized by an outer polyamide layer, a fluorinated polymer median layer, preferably made of PVDF, and an inner polyamide layer. The layers are linked to one another by means of an adhesive binder.

Description

I r WO 94/29626 1 PCT/FR94/00640 PETROL SUPPLY TUBE TECHNICAL FIELD The present invention relates to a pipe for conveying or feeding petrol, in particular in engines, particularly motor vehicle engines. The pipe which is the subject of the invention is a polyamide-based petrol feed pipe.

For safety reasons and to protect the environment, motor vehicle manufacturers impose mechanical characteristics on petrol pipes: strength and flexibility, and characteristics of increased resistance to permeability. The pipes must be as impervious as possible to petroleum products and to their additives, in particular methanol.

PRIOR ART At present, polyamide pipes are commonly employed in the motor vehicle industry. Polyamides represent an ideal material for this pipe application, their mechanical strength being excellent and their flexibility being sufficient for a pipe to withstand, without breaking, the accumulation of flexural motions practically throughout the life of a vehicle. These polyamide pipes no longer meet the new requirements of the motor vehicle manufacturers where permeability is concerned. With the ever increasing presence of methanol in petrol, the sensitivity of polyamide pipes is reflected in a swelling of the pipe resulting in a Sdecrease in the mechanical properties and dimensional

-V

WO 94/29626 changes.

PCT/FR94/00640 DESCRIPTION OF THE INVENTION The objective of the present invention is therefore to overcome these disadvantages while preserving the mechanical properties of the polyamides.

Thus, the present invention provides a polyamide-based petrol feed pipe consisting of an outer layer of polyamide, a middle layer of fluoropolymer, preferably of PVDF, and an inner layer of polyamide, these layers being respectively bonded to each other by layers of adhesive bonding agent.

The subject of the invention is therefore a pipe consisting of five layers made up respectively of PA/bonding agent/fluoropolymer/bonding agent/PA (PA meaning polyamide).

These pipes are particularly suitable for feeding petrol to engines.

The polyamide employed is usually a thermoplastic aliphatic polyamide and especially a polyamide 11 (PA-11), polyamide 12 (PA-12) or polyamide 12,12 (PA-12,12), plasticized or otherwise, or else a polyamide 6 (PA-6) cr polyamide 6,6 The polyamide may optionally be a product modified to withstand impacts, or a copolymer. The polyamides of the outer and inner layers may be identical or different. Each polyamide layer may consist of one or a number of sublayers, each of these sublayers consisting of a different polyamide.

\0 WO 94/29626 3 PCT/FR94/00640 This polyamide may also contain conventional fillers for polyamides. The quantity of filler which is incorporated is itself also conventional and is a function of the specification of the motor vehicle manufacturers. One or both polyamide layers may contain such fillers.

According to an embodiment, this filler consists of a regrind. This term "regrind" refers to the ground product of a pipe misshapen during the manufacturing process, and therefore unsuitable for the application for which it is intended, which is thus recycled. It is therefore possible to grind up these misshapen pipes and to incorporate them into the inner and/or outer layer.

Among the fluoropolymers according to the invention there may be mentioned: vinylidene fluoride (VF2) homo- and copolymers, trifluoroethylene (VF 3 homo- and copolymers, homo- and copolymers, and especially terpolymers, combining residues of 4 chlorotrifluoroethylene (CTFE), tetrafluoroethylene (TFE), hexafluoropropene (HFP) and/or ethylene units and optionally VF2 and/or VF3 units. By way of example there may be mentioned polytetrafluoroethylene (PTFE) and poly(ethylene-tetrafluoroethylene) (ETFE).

A fluoropolymer is also intended to mean WO 94/29626 4 PCT/FR94/00640 mixtures of at least 70 by weight of the above with other polymers.

Among the fluoropolymers those advantageously employed are the vinylidene fluoride homo- and copolymers containing at least 70 by weight of VF2 residues, referred to as PVDF throughout the text. PVDF is also intended to mean mixtures of the above with at least one other thermoplastic polymer, provided that at least 50 by weight of VF2 units is present in the mixture.

Each layer of fluoropolymer may be made up of one or a number of sublayers, each of these sublayers being made up of a different fluoropolymer.

It is found that such a pipe, consisting of a middle layer of PVDF bonded by an adhesive bonding agent to two outer and inner layers of polyamide makes it possible to reduce the permeability by a factor of at least 10 when compared with that of an equivalent polyamide pipe, while maintaining the other properties, such as the cold impact strength, within the specification limits, of the motor vehicle manufacturers.

In order to ensure the adhesion between the polyamide and the fluoropolymer, a polymer containing carbonyl groups in its polymer chain is employed in a known manner, such as a polyurethane, a polyamide, a polyurea, a polyester, a copolymer which has ethylenecarbon monoxide groups or else their copolymer WO 94/29626 5 PCT/FR94/00640 derivatives or their mixtures.

Fluoropolymer may be mixed with this adhesive bonding agent in a proportion of 1 to 50 by weight.

When the bonding agent also contains fluoropolymer it is preferred that the fluoropolymer present in the bonding agent should be the same as that which is in the adjacent fluoropolymer layer(s).

Other thermoplastic polymers or copolymers may also be incorporated into this adhesive bonding agent, provided that the adhesive bonding agent is present in a proportion of at least 50 by weight in the mixture. The adhesive bonding agents of the layers situated, on the one hand, between the outer polyamide layer and the fluoropolymer layer and, on the other hand, between the inner polyamide layer and the fluoropolymer layer may be identical or different. Each layer of bonding agent may consist of one or more sublayers, each of these sublayers consisting of a different bonding agent.

Additional layers may be added both inside and outside the pipe. Such layers may consist of polymers, of sheaths and the like, of colouring additives, of anti-UV agent, antioxidant and, in general, any layer known in the art and which can be added to a polyamide layer.

According to an embodiment, the thickness of the polyamide layers is between 0.3 and 1.8 mm, the i- thickness of the fluoropolymer layer is between 10 .m WO 94/29626 6 PCT/FR94/00640 and 1 mm and the thickness of the layers of adhesive bonding agent is between 10 pm and 1 mm.

The thicknesses of the layers of polyamides and of bonding agents may be identical or different.

Such thicknesses of the constituents are appropriate for the manufacture of petrol feed pipes for engines the diameter of which is generally between 6 and 12 mm.

It is essential, in fact, that the fluoropolymer, and especially the PVDF, should be bonded efficiently to the polyamide. A pipe which does not exhibit bonding between the fluoropolymer and the polyamide cannot have a good flexibility and consequently cannot be folded or bent into an elbow easily by hot forming; in this case the thinnest material forms creases during th operation.

Furthermore, if the layers adhere to one another, poss~,ble condensation of gases between two fluoropolymer/polyamide layers can, in time, result in the deformation of the thinnest part of the pipe.

Furthermore, since the pipes are connected to each other, and to the petrol tank and to the carburettor by couplings, the latter cannot ensure leaktightness if they bear on separated layers. Finally, in the case where the fluoropolymer is PVDF and when the thickness of the PVDF layer inside the pipe is very small, for example from 10 to a few tens of pm, ard without adhesion, a partial vacuum in the )ipe deforms the polyvinylidene fluoride film irreversibly, making the WO 94/29626 7 PCT/FR94/00640 pipe unusable.

The invention also relates to pipes which are identical with the above but of larger diameter. They are suitable, for example, for connecting the buried petrol storage tank and the service station pump.

The pipe according to the invention is obtained in a known manner by coextrusion of the five components under known extrusion conditions which are appropriate to each of the thermoplastic materials.

Coextrusion of the five components facilitates the extrusion of the middle fluoropolymer layer, especially of PVDF, which is relatively difficult when this layer is not "sandwiched".

METHODS OF EMBODYING THE INVENTION The following examples illustrate the invention without limiting it.

EXAMPLE 1 A pipe of 8 mm external diameter, obtained in a conventional manner in a five-substance coextrusion plant, is made up of: an outer layer of PA-12 plasticized with 13 on a mass basis of n-butylbenzenesulphonamide (BBSA) 600 pm in thickness, a layer 150 im in thickness of a bonding agent consisting of a mixture of: parts by weight of thermoplastic polyurethane of polyester type with a Shore A hardness measured according to

I

WO 94/29626 8 PCT/FR94/00640 DIN standard 53-505 equal to 88 and with a relative density of 1.18, parts by weight of an ethylene/vinyl acetate copolymer functionalized by grafting with maleic anhydride with a melting point of 90°C and melt flow of 6 g/10 min at 190 0 C under 2.16 kg, a layer of PVDF which is a VF2 homopolymer with melt flow of 8 g/10 min at 230 0 C under 5 kg, 250 pm in thickness, a 150 pm layer of a bonding agent identical with the bonding agent employed above; an inner layer of 500 pm of PA-12 identical with the polyamide 12 employed above for the outer layer.

This pipe thus obtained exhibits a very low permeability to leaded premium petrol containing 15 of methanol; this pipe exhibits good mechanical properties.

EXAMPLE 2 A PA/bonding agent/PVDF/bonding agent/PA pipe calibrated to the following dimensions: outer diameter 8 mm and inner diameter 6 mm, is produced by coextrusion.

By way of comparison, a single-layer polyamide pipe identical with the above pipe, 1 mm in thickness, is extruded.

The polyamide employed is a PA-12 plasticized I I WO 94/29626 9 PCT/FR94/00640 with 7.5 on a mass basis of n-butylbenzenesulphonamide (BBSA) which has a flexural modulus of 450 MPa (ISO standard 178) and a notched Charpy impact strength of 9 kJ/m 2 at -40 0 C (ISO standard 179).

The bonding agent is a mixture obtained by extruding in a twin-screw extruder PVDF No.l (VF2 homopolymer with a melt flow of 13 min at 230 0 C under 5 kg (ISO standard 1133) mass a copolymer of acrylic-imide type containing the following units 1, 2, 3 and 4 in its structure:

CH

3

CH

3

-CH

2

C-CH

2

C-

I C 0= C 0 C*=0

CH

3 CH3

I

C -CH- C- I I 0= C -N C =0

CH

3 WO 94/29626 PCT/FR94/00640

CH

3 1

CH

2

C-

C =0

I

OH

CH3

I

CH-- C-

C=O

I

0

CH

3 the weight percentage (expressed in relation to the total mass of copolymers) of the acidic and anhydrous monomers 1 and 3 is equa =fo \6 the weight percentage (expressed in relation to the total mass of copolymers) of the imide monomers 2 is tw-enP a 6es% the said copolymer exhibiting a flexural modulus of 4,100 MPa (ISO standard 178) (15 and an impact modifier of the methyl methacrylate butadiene styrene (MBS) core-shell type (35 The PVDF No.2 of the middle layer is a VF2 homopolymer with a melt flow of 8 g/10 min at 230°C under 5 kg (ISO standard 1133).

The impact strength and the permeability are measured for each of the pipes in a test petrol.

oti WO 94/29626 11 PCT/FR94/00640 The standard employed for assessing the impact strength of the pipes is DIN standard 53453. The tests are conducted at The permeability tests are conducted according to the "micro SHED test" method by recirculating test petrol in the pipes. The test petrol TF1, mixture on a volume basis of ethanol (9 isooctane (45.5 and toluene (45.5 In this case the recirculation is performed at 40*C at a pressure of 2 bars.

Example Pipe structure Permeability DIN impact TF at (g/M 2 /24 hi) 2 PA-12/bonding agent/PVDF No.2/ 5 OF/1b banding agent/PA-12 (380 pii/65 VmL/100 pmf/65 pnh/380 pm) Comparative PA-12 69.7 OP/b0 1l mm) OF/1O No failure out of 10 tests according to the standard.

Claims

1. Polyamide-based petrol feed pipe characterized in that it consists of an outer layer of polyamide, a middle layer of fluoropolymer, preferably of PVDF, and an inner layer of polyamide, these layers being respectively bonded to each other by layers of adhesive bonding agent.

2. Pipe according to Claim 1, characterized in that the polyamide employed is chosen from the group consisting of PA-12, PA-12,12, PA-11, PA-6 and PA-6,6.

3. Pipe according to Claim 1 or 2, characterized in that the adhesive bonding agent is a polymer or copolymer containing carbonyl groups in its polymer chain.

4. Pipe according to any one of Claims 1 to 3, characterized in that fillers are incorporated into the polyamide layer(s). Pipe according to Claim 4, characterized in that the filler consists of a "regrind".

6. Pipe according to any one of Claims 1 to characterized in that the thickness of the polyamide layers is between 0.3 and 1.8 mm, in that the thickness of the fluoropolymer layer is between 10 pm and 1 mm and in that the thickness of the layers of adhesive bonding agent is between 10 pm and 1 mm.

7. Pipe according to any one of Claims I to 6, characterized in that it is intended for feeding petrol to engines. 13

8. Pipe according to any one of claims 1 to 7, characterized in that it is obtained by extrusion of its components.

9. Polyamide-based petrol feed pipe, substantially as hereinbefore described with reference to any one of the Examples. Dated 1 March, 1995 Elf Atochemn S.A. Patent Attorneys for the Applicant/Nominated Person SPRUSON FERGUSON 0 0 :00004 ~V R.~ [N:\LU3WI 4353:KEH I INTERNATIONAL SEARCH REPORT International Aplcdton International application No. PCT/FR 94/00640 A. CLASSIFICATION OF SUIECT MATTER IPC 5 F16L9/12 F16L11/12 According to International Patent Classification (IPC) or to both national classification and IPC B. FIELDS SEARCHED Minimum documentation searched (classification system followed by classification symbols) IPC 5 F16L Documentation searched other than minimum documentation to the extent that such documents are included in the fields searched Electronic data base consulted during the international search (name of data base and, where practcal, search terms used) C. DOCUMENTS CONSIDERED TO BE RELEVANT Category' Citation of document, with indication, where appropriate, of the relevant passages Relevant to claim No. A,P WO,A,93 21466 (ITT INDUSTRIES INC.) 28 1,2,7,8 October 1993 see abstract; figure 1 A US,A,4 907 625 (ITO ET AL.) 13 March 1990 1,2,6,8 see claims 1-9; figures 1-10 A DE,C,38 21 723 (TECHNOFORM CAPRANO 1,2,6-8 BRUNNHOFER KG) 21 September 1989 see claims 1-5; figures 1,2 A US,A,3 561 493 (MAILLARD) 9 February 1971 1,2,8 see the whole document S Further documents are listed in the continuation of box C. [M Patent family meme ers are listed in annex. Special categories of cited documents: T later document published after the international filing date A doho g l se of te at w h is nt r piority date and not s, conflict with the application but A document defining the general state of the art which is not cited to understand the principle or theory inderlying the con:idered to be of particular relevance invention earlier document but published on or after the international document of particular relevance; the claimed invention filing date cannot be considered novel or cannot be considered to document which may throw doubts on priority claim(s) or involve an inventive step when the document is taken alone which is cited to establish the publicaton date of another document of particular relevance; the claimed invention citation or other special reason (as specified) cannot be considered to involve an inventive step whe the O0' document referring to an oral disclosunt, use, exhibition or document is co,:mbined with one or more other such docu. other means ments, such combination being obvious to a person skilled document published prior to the international filing date but in the art. later than the priority date claimed document member of the same patent family Date of the actual completion of the international search Date of mailing of the intemational search report 22 August 1994 27. 09. 94 Name and mailing address of the ISA Authorized officer European Patent Office, P.B. 5818 Patentlaan 2 NL 2280 HV Rijswijk Tel.(+31-70) 340-2040, Tx. 31 651 epo nil An ius, P Fax: (+31-70) 340-3016, Form PCT/ISA/210 (second shet) (July 1992) i INTER~NATIONAL SEARCH REPORT nentnaapictoN. lnfonaun o paentfamly ncmeiiPCT/FR 94/00.640 Patent document j Publication patent family Publication cited in search report date member(s) I date WO-A-9321466 28-10-93 US-A- 5284184 08-02-94 US-A-4907625 13-03-90 JP-A- 1171939 06-07-89 JP-A- 2022050 24-01-90 US-A-3561493 09-02-71 NONE Form PCT/ISA/210 (patent ramilly annex) (July 1992) I t W RAI'PORI D9 IAECflRC*IE INTERNATIONALE PCT/FR 94/00640 A. CLASSEMENT D1 L/OIJET DE LA DEMANDE CIB 5 F16L9/12 F16L11/12 Selon Ia classification internationale des brevets (CIB),ou A la fois scion Ia classification nalsonalc et la CIB B. DOMAINES SUR LESQUELS LA RECHERCHE A PORTE Documentation minimaic consaitbe (systame de classification suivi des symboles dc classement) CIB 5 F16L Documentation consulthe autre quc Ia documentation rnimalc dama Ia mesurc oil ccs documents reltvent, des domaines stir lesquels a Porte la rechetche Base de donn~cs 6lcctronxque consult~c aui cours de In recherche intemnationale (norn dc In basc de dorntes, Cat s ca t rtaisable, termes de recherche utiuists) C. DOCUMENTS CONSIDERES COMME PERTINENTS Catkgoric Identification des documents cites, avec, [c cas echeant, l'indcation des passages pertinents no. des revendications; vise A,P WO,A,93 21466 (ITT INDUSTRIES INC.) 28 1,2,7,8 Octobre 1993 voir abr~gd; figure 1 A US,A,4 907 625 (ITO ET AL.) 13 Mars 1990 1,2,6,8 voir revendications, 1-9; figures 1-10 A DE,C,38 21 723 (TECHNOFORM CAPRANO 1,2,6-8 BRUNNHOFER KG) 21 Septembre 1989 voir revendications 1-5; figures 1,2 A US,A,3 561 493 (MAILLARD) 9 F~vrier 1971 1,2,8 voir le document en entier Voir In suite du cadre C pour in fin de Ia liste des documents Les documents de families de brevets sont indiques en annexe *Categories speeialces de documents cf'T' document ultkricur publit apres In date dle dkp~t international ou I a ocuentdefnisa't.Vtat en~al e I tehniuenondate de prlonite et n'apparteneniant pas A IV6tat de In ''dcun d6fiom 1 p art gneraeIn tecniqet o technique pertinent, mis citt pour comprendre ItPcpe consdtr com,.,parict~itemen pebrint:ou I& itorie constituant [a base de l'invcntion document ant~rseur, mais pablit A Ia date de: dftp~t international W document prticUlltrement pertinent; l'invention revendliqute n e peut oti airta cette date atre considWit commit nouvelle ou comme iMpliquant unc activatt W' docunment poulvant jeter tin doute stir uric revendication dc inventive par rapport au document considtra isoltmnrt prioritt ou 616t pour deterrrdner In date de publication d'tine 'Y document pasticulitrement pertinent; l'invention revendiqutc autre citation oti pour tine rison sptciale (telle qlu'indiquiie) ne petit etre considtrte conime lmpliquaafl une activit6 inventive, document se rA1~rant A tine divulgation orale, A tin usage, A lorsque It document est. associA A tin ou plusicurs autres une exposin ttusaremycs documents de minme nature, cette combinaison etant 6vidente document publik: i.ant I a date de dtp6t international, mais pour utin personne du mtier posterleurement Alan date de priontt revendiqute W' document qul fait partie de In m~me farnille de brevets Date A lInquelle Ia recherche internationalle a t effectiventent achevke Date d'exptdition du present rapport de reeberche intemationale 22 A00t,1994

27. 09.94 Nomn at adiresse postale de l'admlnlstratlon chargee de In. recherche intemnationale Fonctionnaire atitot Office Europeen des: Brevets, P.B. 5818 Patentlitan 2 NL 2280 HV Rijswijk Tel. 31-70) 340-2040, Tx. 31 651 eponrl,An u, P Faxc 31.70) 340-3016 n is P Forimutalra PCITlSN/21 (dauilmo fatillia) (lliat 1989k) *RAPPORT DR RECHRERCHJE InTERNATIONALE hzt±i.N. Renvelgrnenti rclatifs Aux membres die (amrl1c8 de bre~vets PCT/FR 94/00640 Document brevet cit6 at e Membre(s) do la Date tic au rapport de recherche pu liein ranille de brevetqs) publication WO-A-9321466 28-10-93 US-A- 5284184 08-02-94 uz.A-4907625 13-03-90 JP-A- 1171939 06-07-89 JP-A- 2022050 24-01-90 DE-C-3821723 21-09-89 AUCUN US-A-356 1493 09-02-7 1 AUCUN Fe.r.mulaim PCTIISA1210 (annex. families do brevet) (Juiflt 1"2)