MICROFIBROUS FABRIC HAVING A SUEDE APPEARANCE, WITHIN THE COLOUR RANGE OF GREY AND BLACK, WITH A HIGH LIGHT FASTNESS, AND PREPARATION METHOD THEREOF

Abstract

A high-quality artificial leather is described, having a suede appearance and colors within the grey-black range, the light fastness of the colors according to the method SAE J 1885 225.6 KJ/m.sup.2 being higher than or equal to 4; the lightfastness of the colors according to the method SAE J 1885 488.8 KJ/m.sup.2 being not lower than 3; said artificial leather having a tassel on the surface of the leather itself. 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; and the total content of carbon black is between 0.025 and 6% by weight.

Claims

1. A non-woven artificial leather, having a suede appearance, said non-woven artificial leather consisting essentially of a non-woven microfibrous component and an elastomeric matrix; the non-woven microfibrous component comprising polyester microfibres having a count of 0.01 to 0.50 dtex and carbon black pigment in a percentage of 0.05 to 2.00% by weight; the elastomeric matrix comprising polyurethane comprising soft and hard segments and carbon black pigment in a percentage of 0 to 10% by weight; wherein the soft segments comprise at least one polycarbonate diol selected from polyalkylene carbonate diols, and at least one polyester diol; wherein the hard segments comprise urethane groups deriving from the reaction between free isocyanate groups and water; and wherein part of the microfibrous component forms tassels on a surface of the artificial leather having an average length ranging from 210 to 400 microns, which provides an improved mottling effect and writing effect.

2. The artificial leather according to claim 1, wherein the microfibrous component comprise polyethylene terephthalate microfibres.

3. The artificial leather according to claim 1, wherein the polyester microfibres contain carbon black in a percentage of 0.15 to 1.50% by weight.

4. The artificial leather according to claim 1, wherein the elastomeric matrix contains the carbon black pigment in a percentage ranging from 0 to 7% by weight.

5. The artificial leather according to claim 1, wherein the elastomeric matrix comprises the carbon black pigment in a percentage ranging from 0.02% to 10% by weight.

6. The artificial leather according to claim 1, wherein the elastomeric matrix comprises the carbon black pigment in a percentage ranging from 0.02% to 7% by weight.

7. The artificial leather according to claim 1, wherein the elastomeric matrix comprises the carbon black pigment in a percentage ranging from 0.02% to 6% by weight.

8. The artificial leather according to claim 1, wherein the overall content of carbon black ranges from 0.075 to 4.25% by weight.

9. The artificial leather according to claim 1, wherein the overall content of carbon black ranges from 0.025 to 6% by weight.

10. The artificial leather according to claim 1, wherein the overall content of carbon black ranges from 0.085 to 3.75% by weight.

11. The artificial leather according to claim 1, wherein the carbon black has an average dimension lower than 0.4 microns.

12. The artificial leather according to claim 1 having a color shade within the grey-black range, wherein the light fastness of the color shade being higher than or equal to 4, according to the method SAE J 1885 225.6 KJ/m.sup.2, and not lower than 3, according to the method SAE J 1885 488.8 KJ/m.sup.2.

13. The artificial leather 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 are derived from methylene-bis-(4-phenylisocyanate) (MDI) and/or from toluene diisocyanate (TDI).

14. The artificial leather according to claim 1, wherein the color shade is characterized by a value of L<70, wherein said value is measured before the artificial leather is subjected to an over-dyeing treatment.

15. The artificial leather according to claim 14, wherein the color shade is characterized by a value of L<55.

16. The artificial leather according to claim 1, wherein the polyester diol is polyhexamethylene adipate diol (PHA).

17. The artificial leather according to claim 1, wherein the hard segment of said polyurethane further comprises 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.

18. The artificial leather according to claim 1, wherein the tassels on the surface of the artificial leather have an average length ranging from 210 to 370 microns.

19. The artificial leather according to claim 1, wherein the tassels on the surface of the artificial leather have an average length ranging from 210 to 350 microns.

Description

EXAMPLES

[0106] The following table indicates the abbreviations used for identifying the raw materials in the examples

TABLE-US-00002 ABBREVIATIONS RAW MATERIAL c.b. Carbon black PET Polyethylene terephthalate PS Polystyrene PVA Polyvinyl alcohol DMF N,N-Dimethylformamide PHC Polyhexamethylene carbonate glycol PNA Polyneopentyladipate glycol MDI 4-4 Diphenylmethanediisocyanate DBA N,N-Dibutylamine

Comparative Example 1 (Standard Product)

[0107] A bi-component fibre of the island-sea type is produced by extruding a pair of polymers insoluble with respect to each other.

[0108] The polymers used are PET and PS, which are extruded and spun to produce a fibre whose sea component consists of PS and the island component PET. The PET has an I.V. value equal to 0.7 dl/g. The fibre thus obtained has the following characteristics:

1. Yarn count: 4.2 dtex

2. Length: 51 mm

[0109] 3. Maximum load strength: 2.08 g/dtex
4. Maximum load elongation: 62%
5. Crimp number: about 4-5/cm
6. PET microfibre strength at maximum load: 3.89 g/dtex
7. PET micro-fibre elongation at maximum load: 72%

[0110] In particular, the fibre is made up of 57 parts by weight of PET and 43 parts by weight of PS. The fibre, if observed in section, reveals the presence of 16 PET micro-fibres englobed in the PS matrix.

[0111] An intermediate felt is prepared with the bi-component fibre, subjected to needling to form a needled felt having a density within the range of 0.1800.200 g/cm.sup.3 and a Unit Weight within the range of 580630 g/m.sup.2.

[0112] The white-coloured needled felt (coordinate CIELAB L equal to 96.3), is immersed in a water solution at 20% weight of polyvinyl alcohol and then subjected to drying. The needled felt thus treated is subsequently immersed in trichloroethylene until the complete dissolution of the polystyrene matrix of the fibres. The non-woven fabric formed is then dried, obtaining an intermediate product called semifinished product D (coordinate CIELAB L, after removal of the sea component, equal to 96.6).

[0113] A polyurethane elastomer is prepared separately, in the form of a solution in DMF. In a first step (pre-polymerization) a solution of PHC and PNA both having a molecular weight of 2,000 in DMF are reacted, at a temperature of 65 C. and under stirring, with MDI in an isocyanate/diols molar ratio of 2.9/1. Three hours after the beginning of the reaction, the pre-polymer thus obtained is cooled to a temperature of 45 C. and diluted with DMF, until a 25% solution of pre-polymer is obtained having a content of free NCO groups of 1.46%.

[0114] DBA and water dissolved in DMF are then slowly added, maintaining a temperature of 45 C., over a period of 5 minutes, in order to have a polyurethane-polyurea having a calculated molecular weight equal to 43,000. After heating to 65 C., the reactor is kept under stirring for a further 8 hours obtaining, in the end, a polyurethane-urea solution which is stable with time having a viscosity at 20 C. of 22,000 mPa*sec. The elastomer solution thus prepared is then diluted with DMF containing Irganox 1010 and Tinuvin 326, with the addition of carbon black in a percentage of 4.8% with respect to PU alone, to form a solution at 14% by weight in PU. The polymer in solution thus obtained, if coagulated with water, is capable of generating structures with a high porosity.

[0115] The semifinished product D is immersed in the solution of the polyurethane elastomer, squeezed by passage through a pair of rolls and subsequently immersed in a water bath maintained at 40 C., for one hour. A coagulated semi-finished product is thus obtained which is passed through a water bath heated to 85 C. to extract the residual solvent and polyvinyl alcohol. The composite is then dried by passage through a heated oven.

[0116] The coagulated and dried semi-finished product having a thickness of 2.30 mm and grey-coloured due to the presence of carbon black in the polyurethane matrix, is then longitudinally cut to obtain two equal laminates, each having a thickness of 1.15 mm which are then subjected to grinding to remove an aliquot of the polyurethane matrix, extract the microfibre component thus forming the tassel. The grinding process is effected by using suitable abrasive papers under such conditions as to reduce the thickness of the composite material to a value of 0.85 mm, producing a microfibrous tassel having a length of 350400 microns (CIELAB L coordinate equal to 55.8).

[0117] The composite is finally treated in suitable dyeing machines (jet), in order to dye the microfibre, according to the technology traditionally used for known synthetic leathers of the suede type, within the grey or black range. In particular, the composite is passed through the Venturi Tube for 1 hour, operating at 125 C. in an aqueous dye bath containing the following dispersed dyes:

TABLE-US-00003 Red dispersed dye (anthraquinonic) 5.4% Blue dispersed dye (anthraquinonic) 22.8% Yellow dispersed dye (amino ketone) 9.4%

[0118] At the end of the dyeing, a dyed microfibrous non-woven fabric is obtained, which, after further treatment under reducing conditions with sodium hydrosulphite in an alkaline environment to eliminate the excess dye, is subjected to finishing treatment.

[0119] The artificial leather thus obtained is subjected to analysis of the physical-mechanical properties (UNI EN 29073-3) and colour fastness to dry and wet rubbing (AATCC 8-2001), to soap washing (AATCC 61-2001), dry washing and light (SAEJ-225.6 KJ/m.sup.2 and 448.8 KJ/m.sup.2).

[0120] The evaluations shown in the following tables, relating to the dyed microfibrous non-woven product, were effected as follows:

[0121] a) for the colour discharge on the test sample (multifibre felt for the washings and cloth for the rubbings) the dirt on the sample is evaluated by comparison with the ISO 105A03 grey scale;

[0122] b) for the shade exchange of the sample before and after the test, the ISO 105A02 grey scale is used.

[0123] The evaluation is effected by comparing the shade exchange or the dirty level with the shade contrasts codified by the appropriate grey scale; an evaluation equal to 5 corresponds to no change in shade/colour transfer, whereas an evaluation of 1 corresponds to the maximum contrast found on the grey scale used.

TABLE-US-00004 TEST Evaluation Longitudinal ultimate tensile strength 410 N Transversal ultimate tensile strength 310 N Longitudinal elongation at 50 N 4.9% Transversal elongation at 50 N 20.0% Wet rubbing AATCC 8-2001 (colour discharge) 4 Dry rubbing AATCC 8-2001 (colour discharge) 4/5 Soap washing AATCC 61-2001 (colour exchange) 5 Dry washing AATCC 61-2001 (colour discharge) 3/4 Dry washing (shade exchange) 5 Dry washing (colour discharge) 3/4 Light fastness, SAE J 1885 225.6 KJ/m.sup.2 (shade exchange) 3 Light fastness, SAE J 1885 488.8 KJ/m.sup.2 (shade exchange) 2/3

Example 2 (Fast Colour from Master SSP with 1% c.b.in Fibre)

[0124] A masterbatch consisting of PET chips with the addition of carbon black at 30% by weight, is polymerized in the solid state in order to increase its Inherent viscosity (I.V.).

[0125] Polymerization is effected in the solid state (SSP) at a temperature of 203 C. and a pressure of 42 mbar for 100 hours.

[0126] The trend of the SSP process is controlled by I.V. measurements effected by means of the following analytic method: 0.5 g of masterbatch are finely ground with a specific grinding mill, and immersed in a 50 cc solution of dichloroacetic acid, maintaining them at 85 C. for 6 hours and subsequently at 70 C. in an ultrasound bath for a further 30 minutes in order to complete the dissolution of the polymer. The solution thus obtained is then analyzed by means of a capillary viscometer of the Ostwald type.

[0127] By comparing the flow time used by the solution to cover a certain portion of the capillary with the time used by the solvent alone, the value of the specific viscosity is obtained. The I.V. value is obtained from the latter value using appropriate mathematical formulae.

[0128] The I.V. before and after the SSP treatment is obtained by means of the above method. The results are as follows: [0129] I.V. masterbatch as such=0.35 dl/g [0130] I.V. masterbatch after SSP=0.71 dl/g

[0131] The chips of masterbatch polymerized in the solid state are then added and suitably mixed, in a proportion of 1/30, with virgin PET chips (I.V. equal to 0.7 dl/g).

The chips thus mixed are then extruded and spun together with a quantity of PS, according to the procedure of the sea-island spinning technology, to produce a bi-component fibre whose sea component consists of PS and the island component consists of PET with the addition of c.b. The fibre thus obtained has the following characteristics:

[0132] 1. Yarn count (denier): 4.2 dtex

[0133] 2. Length: 51 mm

[0134] 3. Maximum load strength: 2.18 g/tex

[0135] 4. Maximum load elongation: 70%

[0136] 5. Crimp number: about 4-5/cm

[0137] 6. PET microfibre strength under maximum load: 3.86 g/dtex

[0138] 7 Elongation of the PET microfibre under maximum load: 68%.

[0139] In particular, the fibre consists of 57 parts by weight of PET with the addition of carbon black and 43 parts by weight of PS. When observed in section, the fibre reveals the presence of 16 micro-fibres of PET+carbon black englobed in the PS matrix.

[0140] An intermediate felt is prepared with the bi-component fibre and is subjected to needling to form a needled felt having a density within the range of 0.1700.190 c/cm.sup.3 and Unitary Weights within the range of 580630 g/m.sup.2.

[0141] The needled felt, having a dark grey colour due to the presence of the fibre with the addition of carbon black (CIELAB L coordinate equal to 35.7), is immersed in an aqueous solution at 20% by weight and then subjected to drying.

[0142] The needled felt thus treated is subsequently immersed in trichloroethylene until the complete dissolution of the polystyrene matrix of the fibres. The non-woven fabric thus formed is then dried, obtaining an intermediate product called semi-finished product D (CIELAB L coordinate, after removal of the sea component, equal to 40.1).

[0143] A polyurethane elastomer is prepared separately, as already described in example 1. The elastomer solution thus prepared is then diluted with DMF containing Irganox 1010 and Tinuvin 326, with the addition of carbon black in a percentage of 4.8% with respect to the PU alone, to form a solution in PU at 14% by weight. The polymer in solution thus obtained, if coagulated in water, is capable of generating structures with high porosities.

[0144] The semi-finished product D is immersed in the solution of the polyurethane elastomer squeezed by passing it through a pair of rolls and subsequently immersed for 1 hour in a water bath maintained at 40 C. A coagulated semifinished product is thus obtained which is passed through a water bath heated to 85 C. to extract the residual solvent and polyvinyl alcohol. The composite material is then dried by passing it through a heated oven.

[0145] The coagulated and dried semifinished product, having a thickness of 2.30 mm and a dark grey colour due to the presence of carbon black both in the fibre and in the polyurethane matrix, is then longitudinally cut to obtain two equal laminates, each having a thickness of 1.15 mm which are then subjected to grinding to remove an aliquot of the polyurethane matrix, to extract the microfibre component thus forming the tassel. The grinding process is effected using specific abrasive papers under such conditions as to reduce the thickness of the composite material to a value of 0.85 mm, producing a microfibrous tassel having a length of 350400 microns (CIELAB L coordinate equal to 33.8).

[0146] The composite is finally treated in suitable dyeing machines (jet), in order to over-dye the microfibre with the addition of carbon black, according to the technology traditionally used for known synthetic leathers, to give a suede type leather, coloured within the range of grey or black. In particular, the composite is passed through the Venturi Tube for 1 hour, operating at 125 C. in an aqueous dyeing bath containing the following dispersed dyes:

TABLE-US-00005 Red dispersed dye (anthraquinonic) 4% Blue dispersed dye (anthraquinonic) 3% Yellow dispersed dye (amino ketone) 3.5%.sup.

[0147] At the end of the dyeing, a dyed microfibrous non-woven product is obtained, which, after further treatment under reducing conditions with sodium hydrosulphite in an alkaline environment to eliminate the excess dye, is subjected to finishing treatment.

The artificial leather thus obtained is subjected to analysis of the physical-mechanical properties and colour fastness, to rubbing, soap washing and a combination of dry washing and light exposure as widely described in example 1. The evaluations are shown in the following table

TABLE-US-00006 TEST Valutazione Longitudinal ultimate tensile strength 450 N Transversal ultimate tensile strength 248 N Longitudinal elongation at 50 N 4.5% Transversal elongation at 50 N 24.0% Wet rubbing AATCC 8-2001 (colour discharge) 4 Dry rubbing AATCC 8-2001 (colour discharge) 4/5 Soap washing AATCC 61-2001 (colour exchange) 5 Dry washing AATCC 61-2001 (colour discharge) 4/5 Dry washing (shade exchange) 5 Dry washing (colour discharge) 4/5 Light fastness, SAE J 1885 225.6 KJ/m.sup.2 (shade exchange) 4/5 Light fastness, SAE J 1885 488.8 KJ/m.sup.2 (shade exchange) 4

Example 3 (Fast Colour from Master SSP with 0.4% c. b. In Fibre and Lighter Dyeing-Shade Colour)

[0148] The chips of masterbatch polymerized in the solid state as described in example 2, are added and suitably mixed to chips of virgin PET (I.V. equal to 0.7 dl/g), in a proportion of 1/75.

[0149] The chips thus mixed are then extruded and spun together with PS, according to the procedure of the sea-island spinning technology, to produce a bi-component fibre, whose sea component consists of PS and the island component consists of PET with the addition of c.b. The fibre thus obtained has the following characteristics:

[0150] 1. Yarn count (denier): 4.2 dtex

[0151] 2. Length: 51 mm

[0152] 3. Maximum load strength: 2.09 g/tex

[0153] 4. Maximum load elongation: 71%

[0154] 5. Crimp number: about 4-5/cm

[0155] 6. PET microfibre strength under maximum load: 3.84 g/dtex

[0156] 7 Elongation of the PET microfibre under maximum load: 74%.

[0157] In particular, the fibre consists of 57 parts by weight of PET with the addition of carbon black and 43 parts by weight of PS. When observed in section, the fibre reveals the presence of 16 micro-fibres of PET+carbon black englobed in the PS matrix.

[0158] An intermediate felt is prepared with the bi-component fibre and is subjected to needling to form a needled felt having a density within the range of 0.2040.208 c/cm.sup.3 and Unitary Weights within the range of 550580 g/m.sup.2.

[0159] The needled felt, having a dark grey colour due to the presence of the fibre containing carbon black (CIELAB L coordinate equal to 50.4), is immersed in an aqueous solution at 20% by weight and then subjected to drying.

[0160] The needled felt thus treated is subsequently immersed in trichloroethylene until the complete dissolution of the polystyrene matrix of the fibres. The non-woven fabric thus formed is then dried, obtaining an intermediate product called semi-finished product D (CIELAB L coordinate, after removal of the sea component, equal to 51.6).

[0161] A polyurethane elastomer is prepared separately, as already described in example 1. The elastomer solution thus prepared is then diluted with DMF containing Irganox 1010 and Tinuvin 326, with the addition of carbon black in a percentage of 0.3% with respect to the PU alone, to form a solution in PU at 14% by weight The polymer in solution thus obtained, if coagulated in water, is capable of generating structures with high porosities.

[0162] The semi-finished product D is immersed in the solution of the polyurethane elastomer squeezed by passing it through a pair of rolls and subsequently immersed for 1 hour in a water bath maintained at 40 C. A coagulated semifinished product is thus obtained which is passed through a water bath heated to 85 C. to extract the residual solvent and polyvinyl alcohol. The composite material is then dried by passing it through a heated oven.

[0163] The coagulated and dried semifinished product, having a thickness of 2.30 mm and a dark grey colour due to the presence of carbon black both in the fibre and in the polyurethane matrix, is then longitudinally cut to obtain two equal laminates, each having a thickness of 1.15 mm which are then subjected to grinding to remove an aliquot of the polyurethane matrix, extract the microfibre component and thus form the tassel. The grinding process is effected by using specific abrasive papers under such conditions as to reduce the thickness of the composite material to a value of 0.85 mm, producing a microfibrous tassel having a length of 300350 microns (CIELAB L coordinate equal to 50.0).

[0164] The composite is finally treated in suitable dyeing machines (jet), in order to over-dye the microfibre containing carbon black, according to the technology traditionally used for known synthetic leathers, to give a suede-type leather, coloured within the grey or black range.

[0165] Unlike what has been observed with the composite materials previously illustrated, the lower amount of carbon black used makes it necessary to use a higher quantity of dyes, if the final colour desired is the same. Starting from a lighter grey shade, on the contrary, a range of lighter colours can be obtained, by over-dyeing, which would otherwise be impossible to produce starting from the grey base of the composite previously illustrated (example 2), in any case maintaining equally high colour fastness performances.

[0166] In particular, the composite is passed through the Venturi Tube for 1 hour, operating at 125 C. in an aqueous dyeing bath containing the following dispersed colours:

TABLE-US-00007 Red dispersed dye (anthraquinonic) 0.7% Blue dispersed dye (anthraquinonic) 1.9% Yellow dispersed dye (amino ketone) 0.5%

[0167] At the end of the dyeing, a dyed microfibrous non-woven fabric is obtained, which, after further treatment under reducing conditions with sodium hydrosulphite in an alkaline environment to eliminate the excess dye, is subjected to finishing treatment. The artificial leather thus obtained is subjected to analysis of the physical-mechanical properties and colour fastness to rubbing, soap washing and a combination of dry washing and light exposure as widely described in example 1. The evaluations are indicated in the following table

TABLE-US-00008 TEST Valutazione Longitudinal ultimate tensile strength 410 N Transversal ultimate tensile strength 240 N Longitudinal elongation at 50 N 5.5% Transversal elongation at 50 N 25.0% Wet rubbing AATCC 8-2001 (colour discharge) 4 Dry rubbing AATCC 8-2001 (colour discharge) 4/5 Soap washing AATCC 61-2001 (colour exchange) 5 Dry washing AATCC 61-2001 (colour discharge) 4/5 Dry washing (shade exchange) 5 Dry washing (colour discharge) 4/5 Light fastness, SAE J 1885 225.6 KJ/m.sup.2 (shade exchange) 4/5 Light fastness, SAE J 1885 488.8 KJ/m.sup.2 (shade exchange) 4

[0168] By comparison, a composite produced with the same procedure, starting however from virgin PET fibres (with no addition of carbon black), required, in order to obtain the same colour shade, the use of a dyeing bath with the following dispersed dyes

TABLE-US-00009 Red dispersed dye (anthraquinonic) 1.3% Blue dispersed dye (anthraquinonic) 3.8% Yellow dispersed dye (amino ketone) 1.3%

Example 4(Non-Regraded Fast Colour with 1% Carbon Black in Fibre)

[0169] The chips of masterbatch as such (containing PET with the addition of carbon black at 30% by weight, I.V. equal to 0.35 dl/g), are added to and suitably mixed, in a proportion of 1/30, with chips of virgin PET (I.V. of 0.7 dl/g).

The chips thus mixed are then extruded and spun together with PS, according to the sea-island spinning technology, to produce a bi-component fibre, whose sea component consists of PS and the island component consists of PET with the addition of carbon black. The fibre thus obtained has the following characteristics:

[0170] 1. Yarn count (denier): 4.2 dtex

[0171] 2. Length: 51 mm

[0172] 3. Maximum load strength: 1.45 g/tex

[0173] 4. Maximum load elongation: 69%

[0174] 5. Crimp number: about 4-5/cm

[0175] 6. PET microfibre strength under maximum load: 2.55 g/dtex

[0176] 7 Elongation of the PET microfibre under maximum load: 72%.

[0177] In particular, the fibre consists of 57 parts by weight of PET with the addition of carbon black and 43 parts by weight of PS. When observed in section, the fibre reveals the presence of 16 micro-fibres of PET+carbon black englobed in the PS matrix.

[0178] An intermediate felt is prepared with the bi-component fibre and is subjected to needling to form a needled felt having a density within the range of 0.2400.260 c/cm.sup.3 and Unitary Weights within the range of 630650 g/m.sup.2. Also during the production of the felt, problems were observed relating to the breakage of the microfibre, which causes a sudden increase in density and frequent needle breaks.

[0179] The needled felt, having a dark-grey colour due to the presence of the fibre with the addition of carbon black (CIELAB L coordinate equal to 35.4), is immersed in an aqueous solution of polyvinyl alcohol at 20% by weight and then subjected to drying.

[0180] The needled felt thus treated is subsequently immersed in trichloroethylene until the complete dissolution of the polystyrene matrix of the fibres. The non-woven fabric thus formed is then dried, obtaining an intermediate product called semi-finished product D (CIELAB L coordinate, after removal of the sea component, equal to 40.3).

[0181] A polyurethane elastomer is prepared separately, as already described in example 1. The elastomer solution thus prepared is then diluted with DMF containing Irganox 1010 and Tinuvin 326, with the addition of carbon black in a percentage of 4.8% with respect to the PU alone, to form a solution in PU at 14% by weight. The polymer in solution thus obtained, if coagulated in water, is capable of generating structures with high porosities.

[0182] The semi-finished product D is immersed in the solution of the polyurethane elastomer, squeezed by passing it through a couple of rolls and subsequently immersed for 1 hour in a water bath maintained at 40 C. A coagulated semifinished product is thus obtained which is passed through a water bath heated to 85 C. to extract the residual solvent and polyvinyl alcohol. The composite material is then dried by passing it through a heated oven.

[0183] The coagulated and dried semifinished product, having a thickness of 2.30 mm and a dark grey colour due to the presence of carbon black both in the fibre and in the polyurethane matrix, is then longitudinally cut to obtain two equal laminates, each having a thickness of 1.15 mm which are then subjected to grinding to remove an aliquot of the polyurethane matrix, extract the microfibre component and thus form the tassel. The grinding process is effected by using suitable abrasive papers under such conditions as to reduce the thickness of the composite material to a value of 0.85 mm, producing a microfibrous tassel having a length of 320370 microns (CIELAB L coordinate equal to 34.0).

[0184] The composite is finally treated in suitable dyeing machines (jet), in order to over-dye the microfibre containing carbon black, according to the technology traditionally used for known synthetic leathers, to give a suede-type leather, coloured within the grey or black range. In particular, the composite is passed through the Venturi Tube for 1 hour, operating at 125 C. in an aqueous dyeing bath containing the following dispersed colours:

TABLE-US-00010 Red dispersed dye (anthraquinonic) 4% Blue dispersed dye (anthraquinonic) 3% Yellow dispersed dye (amino ketone) 3.5%.sup.

[0185] At the end of the dyeing, a dyed microfibrous non-woven fabric is obtained, which, after further treatment under reducing conditions with sodium hydrosulphite in an alkaline environment to eliminate the excess dye, is subjected to finishing treatment.

The artificial leather thus obtained is subjected to analysis of the physical-mechanical properties and colour fastness to rubbing, soap washing and a combination of dry washing and light exposure as widely described in example 1. The evaluations are indicated in the following table

TABLE-US-00011 TEST Evaluation Longitudinal ultimate tensile strength 424 N Transversal ultimate tensile strength 272 N Longitudinal elongation at 50 N 3.6% Transversal elongation at 50 N 22.0% Wet rubbing AATCC 8-2001 (colour discharge) 4 Dry rubbing AATCC 8-2001 (colour discharge) 4/5 Soap washing AATCC 61-2001 (colour exchange) 5 Dry washing AATCC 61-2001 (colour discharge) 4/5 Dry washing (shade exchange) 5 Dry washing (colour discharge) 4/5 Light fastness, SAE J 1885 225.6 KJ/m.sup.2 (shade exchange) 4/5 Light fastness, SAE J 1885 488.8 KJ/m.sup.2 (shade exchange) 4

[0186] The composite has a thickness of 0.82 mm.

Example 5 (Non-Regraded Fast Colour with 2% Carbon Black in Fibre)

[0187] The chips of masterbatch as such (containing PET with the addition of 30% by weight of carbon black, I.V. equal to 0.35 dl/g), are added to and suitably mixed, in a proportion of 1/15, with chips of virgin PET (I.V. of 0.7 dl/g).

[0188] The chips thus mixed are then extruded and spun together with PS, according to the sea-island spinning technology, to produce a bi-component fibre, whose sea component consists of PS and the island component consists of PET with the addition of carbon black. The fibre thus obtained has the following characteristics:

[0189] 1. Yarn count (denier): 4.2 dtex

[0190] 2. Length: 51 mm

[0191] 3. Maximum load strength: 1.4 g/tex

[0192] 4. Maximum load elongation: 62%

[0193] 5. Crimp number: about 4-5/cm

[0194] 6. PET microfibre strength under maximum load: 2.52 g/dtex

[0195] 7. Elongation of the PET microfibre under maximum load: 72%.

[0196] In particular, the fibre consists of 57 parts by weight of PET containing carbon black and 43 parts by weight of PS. When observed in section, the fibre reveals the presence of 16 microfibres of PET+carbon black englobed in the PS matrix.

[0197] An intermediate felt is prepared with the bi-component fibre and is subjected to needling to form a needled felt having a density within the range of 0.2400.260 c/cm.sup.3 and Unitary Weights within the range of 615630 g/m.sup.2.

[0198] The needled felt, having a dark grey colour due to the presence of the fibre containing carbon black (CIELAB L coordinate equal to 25.0), is immersed in an aqueous solution of polyvinyl alcohol at 20% by weight and then subjected to drying.

[0199] The needled felt thus treated is subsequently immersed in trichloroethylene until the complete dissolution of the polystyrene matrix of the fibres. The non-woven fabric thus formed is then dried, obtaining an intermediate product called semi-finished product D (CIELAB L coordinate, after removal of the sea component, equal to 30.3).

[0200] A polyurethane elastomer is prepared separately, as already described in example 1. The elastomer solution thus prepared is then diluted with DMF containing Irganox 1010 and Tinuvin 326, with the addition of carbon black in a percentage of 4.8% with respect to the PU alone, to form a solution in PU at 14% by weight. The polymer in solution thus obtained, if coagulated in water, is capable of generating structures with high porosities.

[0201] The semi-finished product D is immersed in the solution of the polyurethane elastomer, squeezed by passing it through a pair of rolls and subsequently immersed for 1 hour in a water bath maintained at 40 C. A coagulated semifinished product is thus obtained which is passed through a water bath heated to 85 C. to extract the residual solvent and polyvinyl alcohol. The composite material is then dried by passing it through a heated oven.

[0202] The coagulated and dried semifinished product, having a thickness of 2.30 mm and dark-grey colour due to the presence of carbon black both in the fibre and in the polyurethane matrix, is then longitudinally cut to obtain two equal laminates, each having a thickness of 1.15 mm which are then subjected to grinding to remove an aliquot of the polyurethane matrix, extract the microfibrous component and thus form the tassel. The grinding process is effected by using suitable abrasive papers under such conditions as to reduce the thickness of the composite material to a value of 0.85 mm, producing a microfibrous tassel having a length of 320370 microns (CIELAB L coordinate equal to 24.4).

[0203] The composite is finally treated in suitable dyeing machines (jet) in order to over-dye the microfibre containing carbon black, according to the technology traditionally used for already known synthetic leathers, to give a suede-type leather coloured within the grey and black range.

[0204] Unlike what has been observed with the composite products described above, the higher quantity of carbon black used does not allow the same colour range to be reproduced, starting from the composite products already described. The colours listed in the following table, for example, characterized by high sales volumes, cannot be prepared starting from the present composite product due to the greater brightness of the colour shade required with respect to that of the composite produced (CIELAB L coordinate equal to 24.4)

TABLE-US-00012 Colour L 6650 29.86 6750 26.89 6950 32.87

[0205] For other colours, on the other hand, difficulties are observed for reaching the desired colour shade by means of over-dyeing due to the strong colour changes towards red and/or blue shades of the composite product and to the poor contribution of the dyes necessary for effecting the shade correction. The smaller colour range which can be developed on this colour base of the composite product, however, is coupled by a strong increase in resistance on particularly dark colours (black in particular) which in any case require considerable additions of dyes even when starting from the composite product described in examples 2 and 4.

[0206] In particular, the composite is passed through the Venturi Tube for 1 hour, operating at 125 C. in an aqueous dyeing bath containing the following dispersed dyes:

TABLE-US-00013 Red dispersed dye (anthraquinonic) 1% Blue dispersed dye (anthraquinonic) 3% Yellow dispersed dye (amino ketone) 10.5%

[0207] At the end of the dyeing, a dyed microfibrous non-woven fabric is obtained, which, after further treatment under reducing conditions with sodium hydrosulphite in an alkaline environment to eliminate the excess dye, is subjected to finishing treatment.

[0208] The artificial leather thus obtained is subjected to analysis of the physical-mechanical properties and colour fastness to rubbing, soap washing and the combination of dry washing and light exposure as widely described in example 1. The evaluations are indicated in the following table

TABLE-US-00014 TEST Evaluation Longitudinal ultimate tensile strength 395 N Transversal ultimate tensile strength 240 N Longitudinal elongation at 50 N 7.0% Transversal elongation at 50 N 32.0% Wet rubbing AATCC 8-2001 (colour discharge) 4 Dry rubbing AATCC 8-2001 (colour discharge) 4/5 Soap washing AATCC 61-2001 (colour exchange) 5 Dry washing AATCC 61-2001 (colour discharge) 4/5 Dry washing (shade exchange) 5 Dry washing (colour discharge) 4/5 Light fastness, SAE J 1885 225.6 KJ/m.sup.2 (shade exchange) 4/5 Light fastness, SAE J 1885 488.8 KJ/m.sup.2 (shade exchange) 4/5

[0209] PET fibre (with no addition of carbon black) required, in order to obtain the same colour shade, the use of a dyeing bath with the following dispersed dyes:

TABLE-US-00015 Red dispersed dye (anthraquinonic) 5.7% Blue dispersed dye (anthraquinonic) 12.8% Yellow dispersed dye (amino ketone) 18.1%

Comparative Example 6 (Fast Colour from Master SSP with 1% Carbon Black in Fibre and Short Tassel)

[0210] The composite product, prepared as described in example 2, was ground under such conditions as to produce a micro-fibrous tassel having a length ranging from 90 to 120 m (CIELAB L coordinate equal to 33.4).

[0211] The composite is finally treated in suitable dyeing machines (jet), in order to over-dye the microfibre containing carbon black, according to the technology traditionally used for known synthetic leathers of the suede type, within the range of grey or black. In particular, the composite is passed through the Venturi Tube for 1 hour, operating at 125 C. in an aqueous dyeing bath containing the following dispersed dyes:

TABLE-US-00016 Red dispersed dye (anthraquinonic) 3.8% Blue dispersed dye (anthraquinonic) 2.8% Yellow dispersed dye (amino ketone) 3.2%

[0212] At the end of the dyeing, a dyed microfibrous non-woven is obtained, which, after further treatment under reducing conditions with sodium hydrosulphite in an alkaline environment to eliminate the excess dye, is subjected to finishing treatment.

The artificial leather thus obtained shows an evident qualitative decay from an aesthetical point of view due to the excessive exposure of the polyurethane background and to the loss of the writing and marbling effect caused by the particularly short microfibrous tassel. Prototypes of composite products thus produced were considered as being unsuitable by the final user and therefore discarded.

[0213] The evaluation of the physical-mechanical properties and colour resistance tests to rubbing, soap washing and a combination of dry washings and light exposures (already widely described in example 1), are indicated in the following table

TABLE-US-00017 TEST Evaluation Longitudinal ultimate tensile strength 445 N Transversal ultimate tensile strength 250 N Longitudinal elongation at 50 N 4.3% Transversal elongation at 50 N 23.0% Wet rubbing AATCC 8-2001 (colour discharge) 4 Dry rubbing AATCC 8-2001 (colour discharge) 4/5 Soap washing AATCC 61-2001 (colour exchange) 5 Dry washing AATCC 61-2001 (colour discharge) 4/5 Dry washing (shade exchange) 5 Dry washing (colour discharge) 4/5 Light fastness, SAE J 1885 225.6 KJ/m.sup.2 (shade exchange) 4/5 Light fastness, SAE J 1885 488.8 KJ/m.sup.2 (shade exchange) 4

[0214] The composite product has a thickness of 0.78 mm.

Summarazing Table

[0215] The main characteristics of the composite materials described above are summarized hereunder, for a clearer and more convenient reading.

[0216] Comparative example 1 refers to the production of artificial suede leather with no carbon black in the micro-fibrous part.

[0217] Comparative example 6 refers to the production of suede leather having a tassel length of 90-120 microns.

TABLE-US-00018 TEST 1C 2 3 4 5 6C I.V. masterbatch (dl/g) 0.71 0.71 0.35 0.35 0.71 c.b. microfibre content (%) 0 1 0.4 1 2 1 c.b. elastomer content (%) 4.8 4.8 0.3 4.8 4.8 4.8 c.b. total content (%) 1.6 2.3 0.4 2.3 2.9 2.3 fibre count (dtex) 4.2 4.2 4.2 4.2 4.2 4.2 fibre toughness (g/dtex) 2.08 2.18 2.09 1.45 1.40 2.18 fibre elongation (%) 62 70 71 69 62 70 PET microfibre toughness 3.89 3.86 3.84 2.55 2.52 3.86 (g/dtex) PET microfibre elongation 72 68 74 72 72 68 (%) felt luminosity (L) 96.3 35.7 50.4 35.4 25.0 35.7 composite luminosity (L) 55.8 33.8 50.0 34.0 24.4 33.4 tassel length (m) 350-400 320-370 300-350 320-370 320-370 90-120 Fastness to light, SAE J 1885 3 4/5 4 (4/5*) 4/5 (4/5*) 4/5 225.6 KJ/m.sup.2 (shade exchange) Fastness to light, SAE J 1885 2/3 4 3/4 (4*) 4 (4/5*) 4 488.8 KJ/m.sup.2 (shade exchange) increase in the colour fastness of the dye to light, even of 1-1.5 with respect to the grey scale (see examples 1C and 2); by increasing the carbon black content in the fibre, the colour fastness to light increases but the colour range which can be obtained starting from the intermediate microfibrous compound decreases (decrease in the luminosity value L of the same intermediate product); the addition of masterbatch containing carbon black causes a slight decrease in the physical-mechanical properties of the fibre; the masterbatch polymerization process in the solid state (see examples 2 and 3) allows the production of a microfibre with improved mechanical properties, comparable with that of the reference product, without carbon black, described in comparative example 1.