Patent GB-791618-A (GB)
Title: Improvements in the coating of nylon fabrics
IPC: B32B27/00
Filed: 1954-06-28
Abstract: <PICT:0791618/IV (b)/1> <PICT:0791618/IV (b)/2> A woven nylon fabric coated with polyurethane rubber is obtained by successively applying to the fabric a normally tacky, liquid polyesterdiisocyanate intermediate reaction product containing unreacted isocyanate groups and a curing agent therefor, whereby the polyesterdiisocyanate is converted in situ on the fabric to a solid, non-tacky, cured condition with the nylon yarns firmly embedded in the cured rubber, and with the coated fabric remaining porous.  The polyester may be that obtained by reacting a mixture of ethylene and propylene glycols with adipic acid and may have an hydroxyl number 20-120, an acid value less than 2 and a mol. weight of 1700-3000.  The polyester is reacted under anhydrous conditions at 70-150 DEG  C. with a diisocyanate OCN-R-NCO, where R is a divalent hydrocarbon radical, of which a number are specified, e.g. naphthalene-1,5-diisocyanate or p,p1-diphenylmethane diisocyanate, in an amount 20-250 per cent in excess over the amount of diisocyanate required to react with the alcoholic hydroxyl groups present in the polyester.  As shown in Fig. 2, an open leno weave fabric of untwisted continuous multi-filament nylon yarns 10 is drawn from roll 11 and passed through a bath 12 containing a diprimary diamine curing agent as liquid or in solution in an inert organic solvent, e.g. 4,41-diamino diphenyl methane in acetone, although a number of other diamines are referred to.  The treated fabric then passes through an acetone solution of the polyester-diisocyanate intermediate in bath 14 and squeeze rolls 15, and may be subjected to air jet 16 to blow solution from the interstices of the fabric to ensure porosity, e.g. for shoe uppers. The fabric passes through a second solution of diamine in 17 and, without contact with any surface for a sufficient time to effect initial cure, round roll 18 to oven 19 at 100-200 DEG  F., and thence to take up roll 20.  The diamine may be applied before or after the polyester-diisocyanate intermediate or, as indicated, both before and after, and multiple coatings may be obtained by applying polyester-diisocyanate intermediate successively, or alternately with diamine.  The coatings may be applied by brushing, dipping, spreading or spraying.  Alternatively, the open weave nylon fabric 25 in Fig. 4 may be drawn down between adjustable, closely spaced driven rolls 27 containing a bank 28 of methyl isobutyl ketone solution of polyester-diisocyanate intermediate, and then passes through oven 31, containing a humid atmosphere of 70-95 per cent relative humidity at 100-400 DEG  F., obtained by steam heating pipes 32 and live steam injectors 34, whereby water vapour acts as the curing agent, after blowing interstices clear by steam jet 33. The fabric is again unsupported until after an initial cure.  This first application of polyester-diisocyanate intermediate should not be more than 70 grms./100 nylon, so that the fabric is impregnated without deposition external of the fibres, and after curing and standing is dimensionally stabilized.  The fabric may be treated with intermediate and humid atmosphere a second a third time, but after the third coating a cloth liner saturated with water should be wound in with the fabric.ALSO:A woven nylon fabric coated with polyurethane rubber is obtained by successively applying to the fabric a normally tacky, liquid polyesterdiisocyanate intermediate reaction product containing unreacted isocyanate groups and a curing agent therefor, whereby the polyesterdiisocyanate is converted in situ on the fabric to a solid, non-tacky, cured condition with the nylon yarns firmly embedded in the cured rubber, and with the coated fabric remaining porous.  The polyester may be that, obtained by reacting a mixture of ethylene and propylene glycols and adipic acid, having an hydroxyl number 20-120, acid value less than 2, mol. weight 1700-3000.  The polyester is reacted under anhydrous conditions at 70-150 DEG  C. with a diisocyanate OCN-R-NCO, where R is a divalent hydrocarbon radical, of which a number are specified, e.g. naphthalene1,5-diisocyanate or p,p1-diphenylmethane diisocyanate, in amount 20-250 per cent excess over the amount of diisocyanate required to react with the alcoholic hydroxyl groups present in the polyester.  In Fig. 2, an open leno weave fabric of untwisted continuous multifilament nylon yarns 10 is drawn from roll 11 and passed through a bath 12 containing a diprimary diamine curing agent as liquid or in solution in an inert organic solvent (number specified) e.g. 4,41-diamino diphenyl methane in acetone, although a number of other diamines are referred to.  The treated fabric then passes through acetone solution of the polyesterdiisocyanate intermediate in bath 14, and squeeze rolls 15, and may be subjected to air jet 16 to blow solution from the interstices of the fabric to ensure porosity, e.g. for shoe uppers.  The fabric passes through a second solution of diamine in 17 and, without contact with any surface for a sufficient time to effect initial cure, round 18 to oven 19 at 100-200 DEG  F., and thence to take up 20.  The diamine may be applied before or after the polyester-diisocyanate intermediate, or as indicated both before and after, and multiple coatings may be obtained by applying polyester-diisocyanate <PICT:0791618/IV (a)/1> <PICT:0791618/IV (a)/2> intermediate successively, or alternately with diamine.  The coatings may be applied by brushing, dipping, spreading, or spraying.  Alternatively, the open weave nylon fabric 25 in Fig. 4 may be drawn down between adjustable, closely spaced driven rolls 27 containing a bank 28 of methyl isobutyl ketone solution of polyester-diisocyanate intermediate, and then passes through oven 31, containing a humid atmosphere of 70-95 per cent relative humidity at 100-400 DEG  F., obtained by steam heating pipes 32 and live steam injectors 34 whereby water vapour acts as the curing agent, after blowing interstices clear by steam jet 33.  The fabric is again unsupported until after an initial cure.  This first application of polyesterdiisocyanate intermediate should not be more than 70 grms./100 grms. nylon, so that the fabric is impregnated without deposition external of the fibres, and after curing and standing is dimensionally stabilized.  The fabric may be treated with intermediate and humid atmosphere a second and third time, but after the third coating a cloth liner saturated with water should be wound in with the fabric.