Containers having a low permeability to hydrocarbon vapours, and process for producing them

Claim 2

A container or tank for hydrocarbons made from a plastic material, and in particular for fuels, characterized in that at least one surface thereof is coated with a layer of at least one polymer of p-xylylene and/or its derivatives.

Claim 3

A container according to Claim 1, characterized in that it is made of high-density, high-molecular-weight polyethylene.

Claim 4

A container according to Claim 1 or 2, characterized in that the thickness of the layer of the polymer of p-xylylene and/or its derivatives is greater than 0.01 micrometer.

Claim 5

A container according to Claim 3, wherein the thickness is within the range of from 0.1 to 100 micrometers.

Claim 6

A container according to any one of Claims 1 to 4 characterized in that the coating layer is a polymer of a p-­xylylene monomer having the formula: wherein: X represents a (C₁-C₆)-alkyl group, a (C₆-C₁₀)-aryl group, a (C₇-C₁₆)-aralkyl group, a haloalkyl or haloaralkyl group, an acetoxy group, an aminoalkyl group, an arylamino group, cyano, alkoxy, hydroxy, nitro, a halogen atom, a sulphonic radical, a sulphonic ester radical, a phosphorus-based substituent, a sulphide radical, an alkyl-sulphoxide group, or a hydrogen atom, and m is zero or an integer within the range of from 1 to 4.

Claim 7

A container according to Claim 5, characterized in that the p-xylylene monomer is selected from chloro-p-xylylene, dichloro-p-xylylene, cyano-p-­xylylene, iodo-p-xylylene, fluoro-p-xylylene, hydroxymethyl-­p-xylylene, ethyl-p-xylylene, methyl-p-xylylene, aminomethyl-­p-xylylene, carbomethoxy-p-xylylene, and their mixtures.

Claim 8

A container according to any one of Claims 1 to 6, wherein the layer comprises at least one p-xylylene polymer containing the recurrent units : wherein the symbol X and X′, equal to or different from each other, and m and n, equal to or different from each other, have the same meaning as defined in Claim 5.

Claim 9

A process of producing a container or tank for hydrocarbons, and in particular for fuels, comprising placing the tank or container to be coated inside a deposition chamber maintained at a temperature lower than 200°C, and depositing onto the surfaces of the tank or container reactive vapors of p-xylylene or its derivatives having the formula: wherein: X represents a (C₁-C₆)-alkyl group, a (C₆-C₁₀)-aryl group, a (C₇-C₁₆)-aralkyl group, a haloalkyl or haloaralkyl group, an acetoxy group, an aminoalkyl group, an arylamino group, cyano, alkoxy, hydroxy, nitro, a halogen atom, a sulphonic radical, a sulphonic ester radical, a phosphorus-based substituent, a sulphide group, an alkyl-sulphoxide group, or a hydrogen atom, and m is zero or an integer within the range of from 1 to 4.

Claim 10

A process of producing a container or tank for hydrocarbons, and in particular for fuels, comprising placing the tank or container to be coated inside a deposition chamber maintained at a temperature lower than 200°C, and depositing onto the surfaces of the tank or container reactive vapors of p-xylylene or its derivatives having the formula: wherein: X represents a (C₁-C₆)-alkyl group, a (C₆-C₁₀)-aryl group, a (C₇-C₁₆)-aralkyl group, a haloalkyl or haloaralkyl group, an acetoxy group, an aminoalkyl group, an arylamino group, cyano, alkoxy, hydroxy, nitro, a halogen atom, a sulphonic radical, a sulphonic ester radical, a phosphorus-based substituent, a sulphide group, an alkyl-sulphoxide group, or a hydrogen atom, and m is zero or an integer within the range of from 1 to 4.

Claim 11

A process according to Claim 8, wherein the vapors of p-xylylene or its derivatives of formula (I) are obtained by means of a pyrolytic cracking, at a temperature higher than 400°C, from the corresponding dimer of formula: wherein X and X′, equal to or different from each other, and m and n equal to or different from each other, have the same meanings as respectively indicated for X and m in Claim 5.

Claim 12

A process according to Claim 8 or 9, wherein the deposition of the reactive vapors is carried out under a pressure within the range of from 0.01 to 1 mm Hg.

Claim 13

A process according to any one of Claims 8 to 10, wherein the surface to be coated is subjected to a chemical or physical treatment in order to improve the adhesion of the reactive vapors of p-xylylene or its derivatives.

Claim 14

A process according to any one of Claims 8 to 11, wherein p-xylylene monomers or their derivatives of formula (I) are in admixture with minor amounts of at least one other monomer.