Pipes and tubular conduits – Flexible – Distinct layers
Reexamination Certificate
1998-12-14
2001-07-31
Pyon, Harold (Department: 1772)
Pipes and tubular conduits
Flexible
Distinct layers
C138S140000, C428S036900, C428S036910, C428S036920, C428S413000, C428S475800, C428S476100, C523S215000, C524S251000
Reexamination Certificate
active
06267148
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a polyamide-based electrically conductive resin composition and products using the same. More particularly, the present invention relates to a polyamide-based electrically conductive resin composition which has an improved heat-aging resistance and oxygenated-gasoline (i.e. sour gasoline) resistance as well as an excellent balance of physical properties such as fuel oil resistance, antistatic characteristics, elongation, flexibility and the like and is useful as an inner tube material, and a tube using the same.
BACKGROUND OF THE INVENTION
Resin materials endowed with conductivity are used in a very wide range of applications such as anti-electrostatic products, surface-exothermic materials, CV cables, electrically conductive paints and ink, IC packing materials, shielding materials for electromagnetic waves and the like. There are also used resin tubes endowed with conductivity for the purpose of transporting fuel so as to remove static electricity generated by friction during the transportation and induced by charged gasoline through the filter.
As a means to impart conductivity to the resin, a method of adding to a resin, for example, carbonaceous materials like carbon black as a typical example is the most commonly conducted [JP-A-H07-286103 (1995) and JP-B-H08-13902 (1996), wherein the term “JP-A” as used herein means a laid-open publication for an unexamined application while the term “JP-B” means a publication after examined.] and, as for polyamide resin, it is well-known that an electrically conductive polyamide resin can be obtained by the mixing with conductive carbon black. There is a defect, however, that the heat-aging resistance of a polyamide resin is reduced when mixed with the conductive carbon black. Moreover, when such a resin is used as a tube for fuel oil, the oxygenated-gasoline resistance is far below the satisfactory level.
The addition of a phenolic or organophosphate heat-resistant stabilizer to a polyamide resin in order to improve heat-aging resistance is commonly known in the art but the effect is little in a polyamide resin mixed with the conductive carbon black and scarcely serves to an improvement.
JP-B-H03-61701 (1991) disclosed a method for improving heat-aging resistance by mixing polyamide containing conductive carbon black with copper iodide and potassium iodide. However, since copper iodide and potassium iodide are not compatible with a polyamide resin, it is difficult to make them uniformly dispersed in the resin. They also give rise to a problem that the surface condition of a tube obtained by extrusion (i.e. skin of the hose manufactured by extrusion) is deteriorated. Additionally, the oxygenated-gasoline resistance has been little improved.
There is also a report on the study of the effect of preventing oxidation by adding a phenol, secondary amine, hindered amine antioxidant to a monomer of nylon 6 (6-hexanelactam) [Lanska, B., Poly. Degrad. Stab., 53 (1996) 99-109] but this method does not relate to the addition of carbon black and the report does not investigate the effect of the antioxidant with regard to preventing aging deterioration of physical properties of nylon.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a resin composition which is excellent in electrical conductivity, heat-aging resistance and oxygenated-gasoline resistance.
It is another object of the present invention to provide a tube produced by using the resin composition having excellent conductivity, heat-aging resistance and oxygenated-gasoline resistance.
We have investigated additives which can improve both heat-aging resistance and oxygenated-gasoline resistance of an electrically conductive polyamide mixed with conductive carbon black and have found that secondary aromatic amines can improve heat-aging resistance and oxygenated-gasoline resistance of the conductive polyamide resin.
Accordingly, the present invention provides following conductive polyamide resin compositions and tubes manufactured by using the same.
(1) A conductive resin tube comprising one or more layers, wherein at least the most inner layer of the said tube comprising a conductive polyamide resin composition containing from 6 to 15 parts by weight of conductive carbon black and from 0.3 to 5 parts by weight of secondary aromatic amine for 100 parts by weight of a polyamide resin.
(2) The conductive resin tube as described in the above (1), wherein the polyamide resin is nylon 11 or nylon 12.
(3) The conductive resin tube as described in the above (1), wherein the tube has an outer layer comprising materials selected from a group of polyamide, epichlorohydrin rubber, NBR, a mixture of NBR with polyvinyl chloride, chlorosulfonated polyethylene rubber, chlorinated polyethylene rubber, acrylic rubber(ACM), chloroprene rubber(CR), ethylene-propylene rubber(EPR), ethylene-propylene diene rubber(EPDM), NBR-EPDM blend rubber and a thermoplastic elastomer containing vinyl chloride, olefin, ester or amide.
(4) The conductive resin tube as described in the above (1), wherein the tube is used for the transport of fuel oil.
(5) The conductive resin tube as described in any of the above (1) to (4), wherein the secondary aromatic amine is selected from a group of phenyl-&agr;-naphthylamine, phenyl-&bgr;-naphthylamine, N-phenyl-N′-(p-toluene-sulfonyl)-p-phenylenediamine, 4,4′-bis(&agr;,&agr;-dimethyl-benzyl)-diphenylamine, reaction products of diphenylamine with acetone, reaction products of diphenylamine and aniline with acetone, substituted diphenylamine, N,N′-diphenyl-p-phenylenediamine and N,N′-di-2-naphthyl-p-phenylenediamine, octylated diphenylamine, N,N′-diphenyl-p-phenylenediamine, N,N′-di-2-naphthyl-p-phenylenediamine, N-phenyl-N′-isopropyl-p-phenylene-diamine, N-phenyl-N′-(1,3-dimethylbutyl)phenylenediamine.
(6) A conductive resin tube structure comprising a single- or multi-layer conductive resin tube and a protective member disposed partially or totally on the outer peripheral surface of the tube, at least the most inner layer of the said tube comprising a conductive polyamide resin composition containing from 6 to 15 parts by weight of conductive carbon black and from 0.3 to 5 parts by weight of secondary aromatic amine for 100 parts by weight of a polyamide resin.
(7) The conductive resin tube structure as described in the above (6), wherein the protective member is a member of solid or sponge form comprising a material selected from ethylene-propylene rubber(EPR), ethylene-propylene diene rubber(EPDM) and a thermoplastic elastomer containing vinyl chloride or olefin.
(8) The conductive resin tube as described in the above (6) or (7), wherein the secondary aromatic amine is selected from a group of phenyl-&agr;-naphthylamine, phenyl-&bgr;-naphthylamine, N-phenyl-N′-(p-toluene-sulfonyl)-p-phenylenediamine, 4,4′-bis(&agr;,&agr;-dimethyl-benzyl)-diphenylamine, reaction products of diphenylamine with acetone, reaction products of diphenylamine and aniline with acetone, substituted diphenylamine, N,N′-diphenyl-p-phenylenediamine and N,N′-di-2-naphthyl-p-phenylenediamine,octylated diphenylamine, N,N′-diphenyl-p-phenylenediamine, N,N′-di-2-naphthyl-p-phenylenediamine, N-phenyl-N′-isopropyl-p-phenylenediamine, N-phenyl-N′-(1,3-dimethylbutyl)phenylenediamine.
(9) A conductive polyamide resin composition containing from 6 to 15 parts by weight of conductive carbon black and from 0.3 to 5 parts by weight of secondary aromatic amine for 100 parts by weight of a polyamide resin.
(10) A shaped article comprising the composition of the polyamide resin described in the above (9).
DETAILED DESCRIPTION OF THE INVENTION
(1) Resin Compositions
The composition of the conductive resin of the present invention contains a polyamide resin, conductive carbon black and a secondary aromatic amine as essential constituents and may contain other constituents if desired. Each of these constituents will be descri
Itoh Hiroaki
Katayama Kazutaka
Murakami Koyo
Foutch Louise A.
LaPointe Dennis G.
Mason & Assoc., P.A.
Nolan Sandra M.
Pyon Harold
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