Multi-layer tubing having electrostatic dissipation for handling hydrocarbon fluids

An elongated multi-layer tubing for connection to a motor vehicle system to handle fluids containing hydrocarbons comprising:

• a first layer disposed radially innermost and having an inner surface capable of prolonged exposure to a fluid containing hydrocarbons and an outer surface spaced a first predetermined radial thickness from the inner surface, the first layer consisting essentially of an extrudable, melt-processible thermoplastic;
• a second layer having a second predetermined radial thickness at most equal to the thickness of the first layer, the second layer homogeneously connected to the first layer and consisting essentially of an extrudable, melt-processible thermoplastic capable of sufficiently permanent laminar adhesion with the first layer to prevent delamination during a desired lifetime of said tubing, at least one of the first and second layers resistant to permeation by hydrocarbons;
• a third layer having a third predetermined radial thickness greater than the thickness of the first layer, the third layer homogeneously connected to the second layer and consisting essentially of an extrudable, melt-processible thermoplastic chemically dissimilar to the thermoplastic material employed in the second layer and capable of sufficiently permanent laminar adhesion to the second layer to prevent delamination during said desired lifetime of said tubing;
• and
• wherein the melt-processible thermoplastic material employed in the first, second, and third layers respectively upon lamination provides tubing which has a passive hydrocarbon permeation rate less than about 0.5 g/m.sup.2 in a 24 hour interval, an elongation at break of at least 150%, an ability to resist impacts of at least 2 foot-pounds at temperatures below about -20.degree. C., a tensile strength of at least 25 N/mm.sup.2 and a burst strength at 23.degree. C. and 120.degree. C. of at least 20 bar;
• and
• wherein the extrudable, melt-processible thermoplastic material employed in the second layer is selected from the group consisting of polyvinylidine fluoride polymers, polyvinyl polymers, blends of polyvinyl acetate and urethane, and mixture thereof.

An elongated multi-layer tubing for connection to a motor vehicle system to handle fluids containing hydrocarbons comprising:

• a first layer disposed radially innermost and having an inner surface capable of prolonged exposure to a fluid containing hydrocarbons and an outer surface spaced a first predetermined radial thickness from the inner surface, the first layer consisting essentially of an extrudable, melt-processible thermoplastic;
• a second layer having a second predetermined radial thickness at most equal to the thickness of the first layer, the second layer homogeneously connected to the first layer and consisting essentially of an extrudable, melt-processible thermoplastic capable of sufficiently permanent laminar adhesion with the first layer to prevent delamination during a desired lifetime of said tubing, at least one of the first and second layers resistant to permeation by hydrocarbons;
• a third layer having a third predetermined radial thickness greater than the thickness of the first layer, the third layer homogeneously connected to the second layer and consisting essentially of an extrudable, melt-processible thermoplastic chemically dissimilar to the thermoplastic material employed in the second layer and capable of sufficiently permanent laminar adhesion to the second layer to prevent delamination during said desired lifetime of said tubing;
• and
• wherein the extrudable, melt-processible thermoplastic material employed in the second layer is a polyester thermoplastic selected from the group consisting of polybutylene terephthalate, polyethylene terephthalate, polyteremethylene terephthalate, and mixtures thereof.

An elongated multi-layer tubing for connection to a motor vehicle system to handle fluids containing hydrocarbons comprising:

• a first layer disposed radially innermost and having an inner surface capable of prolonged exposure to a fluid containing hydrocarbons and an outer surface spaced a first predetermined radial thickness from the inner surface, the first layer consisting essentially of an extrudable, melt-processible thermoplastic;
• a second layer having a second predetermined radial thickness at most equal to the thickness of the first layer, the second layer homogeneously connected to the first layer and consisting essentially of an extrudable, melt-processible thermoplastic capable of sufficiently permanent laminar adhesion with the first layer to prevent delamination during a desired lifetime of said tubing, at least one of the first and second layers resistant to permeation by hydrocarbons;
• a third layer having a third predetermined radial thickness greater than the thickness of the first layer, the third layer homogeneously connected to the second layer and consisting essentially of an extrudable, melt-processible thermoplastic chemically dissimilar to the thermoplastic material employed in the second layer and capable of sufficiently permanent laminar adhesion to the second layer to prevent delamination during said desired lifetime of said tubing;
• wherein the extrudable, melt-processible thermoplastic material employed in the first and third layers is zinc chloride resistant Nylon 6 and the thermoplastic material employed in the second layer is selected from the group consisting of co-polymers of alkenes having less than four carbon atoms and vinyl alcohol, copolymers of alkenes having less than four carbon atoms and vinyl acetate, and mixtures thereof.