Microfibrous fabric having a suede appearance, within the colour range of grey and black, with a high light fastness, and preparation method thereof
An artificial leather having a suede appearance and colors within the grey-black range and high color fastness comprising a microfibrous component and an elastomeric matrix; the microfibrous component consisting of polyester microfibers having a count of 0.01 to 0.50 dtex; the elastomeric matrix consisting of polyurethane consisting of soft and hard segments; the ratio between the elastomeric matrix and the microfibrous component ranging from 20/80 and 50/50 by mass; the microfibrous component containing carbon black pigment in a percentage of 0.05 to 2.00% by mass; the elastomeric matrix containing carbon black pigment in a percentage of 0 to 10% by weight; the carbon black always having an average dimension smaller than 0.4 microns. The average length of the tassel is between 200 and 500 microns. The soft segments consist of at least one polycarbonate diol selected from polyalkylene carbonate diols and at least one polyester diol. The hard segments consist of urethane groups deriving from the reaction between free isocyanate groups and water. The total content of carbon black is between 0.025 and 6% by weight.
1. A process for the production of an artificial leather having a suede appearance, a color fastness to light, higher than or equal to 4, according to the method SAE J 1885 225.6 KJ/m 2 , and a color fastness to light not lower than 3, according to the method SAE J 1885 488.8 KJ/m 2 , said process comprising the following steps:
a) spinning bi-component fibers of the “sea-island” type, in which the “island” component consists of a polyester and 0.05% to 2% by weight of carbon black and the “sea” component consists of a polymer immiscible with the island component;
b) preparing a mono-layer felt by connecting the bi-component fibers through needle punching;
c) impregnating the mono-layer felt with a polyurethane (PU) or a polyurethane dispersion (PUD) binder capable of withholding the “island” component during the subsequent elimination phase of the “sea” component;
d) dissolving the “sea” component with an organic solvent to give a microfibrous intermediate product;
e) impregnating the microfibrous intermediate product with an elastomeric matrix solution and/or dispersion comprising one or more polyurethanes and carbon black, the latter being present in a quantity of 0.02 to 6% by weight, with respect to the polyurethane, said polyurethane being made up of soft segments and hard segments, said soft segments consisting of at least one polyalkylene carbonate diol and at least one polyester diol; said hard segments consisting of urethane and/or ureic groups deriving from the reaction between free isocyanate groups and water;
f) eliminating the organic solvent to give a raw semi-finished product;
g) grinding the surface of the raw semi-finished product to yield ground raw semi-finished product having a suede appearance; and
h) overdyeing the ground raw semi-finished product with dispersed dyes to obtain an artificial leather having a suede appearance, a color fastness to light higher than or equal to 4, according to the method SAE J 1885 225.6 KJ/m 2 , and a color fastness to light not lower than 3, according to the method SAE J 1885 488.8 KJ/m 2 .
2. The process according to claim 1 , wherein the polyester containing the carbon black has an Inherent Viscosity (I.V.) value not lower than that of the other polyester.
3. The process according to claim 1 , wherein carbon black is contained in the microfibres in a quantity of 0.15 to 1.50% by weight.
4. The process according to claim 1 , wherein the microfibres are polyethylene terephthalate, polytrimethylene terephthalate, or polybutylene terephthalate.
5. The process according to claim 4 , wherein the microfibres are polyethylene terephthalate microfibres.
6. The process according to claim 4 , wherein the microfibres are previously subjected to a polymerization processes in the solid state to increase the length of the polymeric chains.
7. The process according to claim 1 , wherein the dyeing step is conducted at a temperature ranging from 100° C. to 140° C.
8. The process according to claim 1 , wherein the carbon black has an average particle-size less than 0.4 microns.
9. The process according to claim 1 , wherein the ratio between the elastomer matrix and the microfibrous component ranges from 20/80 to 50/50 by mass.
10. The process according to claim 1 , wherein part of the microfibrous component forms tassels on a surface of the artificial leather having a length from 200 to 500 μm.
11. The process according to claim 10 , wherein length of the tassels range from 210 to 400 μm.
12. The process according to claim 1 , wherein the artificial leather is a non-woven artificial leather.
13. The process according to claim 1 , wherein the microfibrous component comprising polyester microfibres having a count of 0.01 to 0.50 dtex.
14. The process according to claim 1 , wherein
the polyester diols are selected from the group consisting of polyhexamethylene adipate diol (PHA), poly(3-methylpentamethylene) adipate diol (PMPA), polyneopentyl adipate diol (PNA), and polycaprolactone diol (PCL);
the polyalkylenecarbonate diols are selected from the group consisting of polytetramethylene carbonate diol (PTMC), polypentamethylene carbonate diol (PPMC), polyhexamethylene carbonate diol (PHC), polyheptamethylene carbonate diol, polyoctamethylene carbonate diol, polynonamethylene carbonate diol, polydecamethylene carbonate diol, poly-(2-methyl-pentamethylene carbonate)diol, and poly-(2-methyl-1-octamethylene carbonate) diol; and
the isocyanate groups derive from methylene-bis-(4-phenylisocyanate) (MDI) and/or from toluene diisocyanate (TDI).
15. The process according to claim 1 , wherein the polyester diol is polyhexamethylene adipate diol (PHA).
16. The process according to claim 1 , wherein the hard segments of said polyurethane further comprise one or more compounds selected from the group consisting of 2,2-dimethylol-propanoic acid, 2,2-dimethylol-butanoic acid, N-methyl-diethanolamine, dihydroxy alkyl amines, di-amino-alkyl amines, quaternary ammonium salts, and polyoxyalkyl ethers.
17. A process for the production of an artificial leather having a suede appearance, a color fastness to light, higher than or equal to 4, according to the method SAE J 1885 225.6 KJ/m 2 , and a color fastness to light not lower than 3, according to the method SAE J 1885 488.8 KJ/m 2 , said process comprising the following steps:
a) spinning bi-component fibers of the “sea-island” type, in which the “island” component consists of a polyester and 0.05% to 2% by weight of carbon black and the “sea” component consists of a polymer immiscible with the island component;
b) preparing a mono-layer felt by connecting the bi-component fibers through needle punching;
c) impregnating the mono-layer felt with a polyvinyl alcohol (PVA) binder capable of withholding the “island” component during the subsequent elimination phase of the “sea” component;
d) dissolving the “sea” component with an organic solvent to give a microfibrous intermediate product;
e) impregnating the microfibrous intermediate product with an elastomeric matrix solution and/or dispersion comprising one or more polyurethanes and carbon black, the latter being present in a quantity of 0.02 to 6% by weight, with respect to the polyurethane, said polyurethane being made up of soft segments and hard segments, said soft segments consisting of at least one polyalkylene carbonate diol and at least one polyester diol; said hard segments consisting of urethane and/or ureic groups deriving from the reaction between free isocyanate groups and water;
f) eliminating the organic solvent and binder to give a raw semi-finished product;
g) grinding the surface of the raw semi-finished product to yield ground raw semi-finished product having a suede appearance; and
h) overdyeing the ground raw semi-finished product with dispersed dyes to obtain an artificial leather having a suede appearance, a color fastness to light higher than or equal to 4, according to the method SAE J 1885 225.6 KJ/m 2 , and a color fastness to light not lower than 3, according to the method SAE J 1885 488.8 KJ/m 2 .