A sol-gel coating to give coated substrates barrier properties and method of applications thereof

A method for coating a cellulose-comprising substrate, comprising:

• applying a coating composition on at least one surface of the cellulose-comprising substrate;
• wherein the composition comprises:
• (A) at least one silane selected from the group consisting of:
• vinyltrimethoxysilane, methyltrimethoxysilane, trimethoxysilane, methyltriethoxysilane, triethoxypropylsilane, thriethoxysilane, (3-Mercaptopropyl)trimethoxysilane, (3-Mercaptopropyl)triethoxysilane, 3-(Trimethoxysilyl)propyl methacrylate, 3-(Triethoxysilyl)propyl methacrylate, Glycidoxypropyltrimethoxysilane, Bis[3-(triethoxysilyl)propyl] tetrasulfide, 1,2-bis(triethoxysilyl)ethane, N-[3-(trimethoxysilyl)propyl] aniline, Aminopropyltriethoxysilane, Bis-[3-(triethoxysilyl)propyl] amine, Bis-[3-(trimethoxysilyl)propyl] amine, Triethoxyphenylsilane and trimethoxyphenylsilane, Trimethoxyvinylsilane, Triethoxyvinylsilane, vinyltrimethylsilane, chlorovinylsilane, chlorodimethylvinylsilane and mixtures thereof,
• (B) from 0.01% to 3% by weight relative to the weight of the at least one silane of a catalyst selected from a monoprotic and/or a polyprotic acid,
• and a dispersing agent selected from the group consisting of water and a hydroalcoholic solution comprising a linear or branched C1 to C4 alcohol and more than 55% by volume water relative to the volume of the dispersing agent.

A coating composition, comprising:

• (A) at least one silane selected from the group consisting of:
• triethoxypropylsilane, methyltriethoxysilane, methyltrimethoxysilane, trimethoxysilane, triethoxysilane, and mixtures thereof,
• (B) from 0.01% to 3% by weight relative to the weight of the at least one silane of a catalyst selected from a monoprotic and/or a polyprotic acid,
• and a dispersing agent selected from the group consisting of water and a hydroalcoholic solution comprising a linear or branched C1 to C4 alcohol and more than 55% by weight water relative to the weight of the dispersing agent.

A composite coated article comprising:

• a first layer consisting of a substrate selected from the group consisting of cellulose-comprising substrates, metals or plastic substrates
• at least a second layer comprising a coating composition comprising:
• (A) at least one silane selected from the group consisting of:
• triethoxypropylsilane, methyltriethoxysilane, methyltrimethoxysilane, trimethoxysilane, triethoxysilane, and mixtures thereof,
• (B) from 0.01% to 3% by weight relative to the weight of the at least one silane of a catalyst selected from a monoprotic and/or a polyprotic acid,
• and a dispersing agent selected from the group consisting of water and a hydroalcoholic solution comprising a linear or branched C1 to C4 alcohol and more than 55% by weight water relative to the weight of the dispersing agent.

A method for coating a substrate, comprising the steps of:

• a) providing a substrate selected among cellulose-comprising substrates, metals or plastic substrates,
• b) preparing a coating composition,
• c) applying the coating composition on at least one surface of the substrate to obtain a preliminary composite coated article, and
• d) drying the preliminary composite coated article at a temperature ranging from 20° C. for several days to 280° C. for less than 1 minute, to obtain the composite coated article
• wherein the coating composition comprises:
• (A) at least one silane selected from the group consisting of:
• triethoxypropylsilane, methyltriethoxysilane, methyltrimethoxysilane, trimethoxysilane, triethoxysilane, and mixtures thereof,
• (B) from 0.01% to 3% by weight relative to the weight of the at least one silane of a catalyst selected from a monoprotic and/or a polyprotic acid,
• and a dispersing agent selected from the group consisting of water and a hydroalcoholic solution comprising a linear or branched C1 to C4 alcohol and more than 55% by weight water relative to the weight of the dispersing agent.

A method for preparing a coating composition comprising:

• (A) at least one silane selected from the group consisting of:
• triethoxypropylsilane, methyltriethoxysilane, methyltrimethoxysilane, trimethoxysilane, triethoxysilane, and mixtures thereof,
• (B) from 0.01% to 3% by weight relative to the weight of the at least one silane of a catalyst selected from a monoprotic and/or a polyprotic acid,
• a dispersing agent selected from the group consisting of water and a hydroalcoholic solution comprising a linear or branched C1 to C4 alcohol and more than 55% by weight water relative to the weight of the dispersing agent, and
• (C) optionally from 0.30% to 10% by weight relative to the weight of the at least one silane of a filler composition comprising
• c1) an inorganic filler composition comprising at least one inorganic filler selected from the group consisting of silicon dioxide, aluminum oxides, phyllosilicates, inosilicates, tectosilicates, talcum powder, zinc sulphate, magnesium, oxide, zinc flakes, talc, kaolin, albarine, dolomite, cerium oxide, magnesium carbonate, calcium carbonate, sodium aluminate, calcium sulphate, barium sulphate, zinc stearate, and a mixture thereof;
• and/or
• c2) an organic filler composition comprising at least one organic filler selected from the group consisting of cellulose, microfibrillated cellulose, nanofibrillated cellulose, cellulose microcrystals, starch, chitin or a mixture thereof;
• said method comprising the steps of:
• (i) dispersing components (A), (B) and optionally (C) in the dispersing agent to obtain a mixture, and
• (ii) stirring the mixture obtained from step (i) until a viscosity of 5-5000 cps is obtained and until room temperature is reached, to obtain the coating composition.