Bleaching and dyeing; fluid treatment and chemical modification – Process of printing permanently on substrate – other than...
Reexamination Certificate
2002-05-21
2004-08-17
Robertson, Jeffrey B. (Department: 1712)
Bleaching and dyeing; fluid treatment and chemical modification
Process of printing permanently on substrate, other than...
C008S494000, C008S552000, C008S581000, C008S602000, C516S055000, C516S069000, C516S102000, C524S588000, C524S590000, C524S591000, C428S423100, C428S447000, C442S157000
Reexamination Certificate
active
06776804
ABSTRACT:
Vast numbers of garments are produced every year.
The aesthetics of the garment are often enhanced by printing, for example, the manufacturer's logo or some other design onto the garment. This applies in particular to leisure wear, e.g. T-shirts. One of the principal features of leisure wear is comfort. This generally means that mostly very elastic, stretchable fabrics are used.
Printing T-shirts is an industry in its own right. With T-shirts, in particular, the design is generally printed onto the garment after it has been made up into a garment.
As with other clothing, the printed design has to be fast to rubbing and to washing.
It is normal to use pigments, as opposed to substantive dyes, as the colours in the prints, as the application processes for pigments are very much more straightforward and only require a fixation process after the printing. Substantive dye printing is more suited to printing long runs of fabric before it is made into individual garments.
In pigment printing, the pigment is applied together with a binder, which holds the pigments in place on the fabric. The binder is a clear, film-forming, flexible polymer that coats both the pigments and the fibres. The fixation process serves to allow the binder to spread out and then crosslink. The fixation process is generally a treatment at an elevated temperature for a short time,—e.g. 3 minutes at 150° C. After fixation, the binder is an insoluble film covering the surface of the fibres.
For woven fabrics, such as sheeting, shirting and most dress goods, there is a very limited amount of stretch in the fabric. These fabrics are often printed with pigments. The binders used for this purpose are nearly always based on polymers of acrylic esters or butadiene/acrylic ester copolymers. They give excellent fastness and a soft handle. However they are totally inadequate for printing on fabrics that have a high degree of stretch, such as knitted cotton interlock, as they do not stretch with the fabric and therefore crack when the fabric is stretched.
When the base fabric is very stretchable, as is usual for leisure wear, the printed mark must also be stretchable, or else it will either prevent the fabric from stretching and so greatly impair the aesthetic appeal of the garment, or else it will crack when the fabric is stretched and spoil the visual impact of the design. It is normal practice to use plastisol inks, i.e. inks which are based on polyvinyl chloride (PVC) emulsions, for this type of application.
For several reasons, however, there is a strong motivation in the industry to get away from compositions containing PVC.
Plastisol inks usually also contain plasticisers. These are present because PVC alone is a very rigid plastic and has to be softened or plasticised to give it the necessary degree of flexibility. The plasticisers are often phthalate esters and may be harmful to the environment. They may be leached out of the print during washing or may evaporate, particularly during drying in garment production processes or in household driers.
The normal plastisol inks also usually contain significant amounts of heavy metals, such as lead or cadmium, as stabilisers for the PVC which are often undesirable. Thus a strong demand exists in industry dealing with printing stretched textile material to find a method for printing such articles without the use of PVC, a plasticiser like e.g. phthalate esters and/or heavy metals.
JP-A 2-91280 discloses a binder composition for pigment printing containing a silicone emulsion and a polyurethane water dispersion or solution, which is said to reveal good fastness to rubbing and resistance to washing. However, with respect to open time in screen these formulations do not meet the highest requirements.
It has now surprisingly been found that the drying of the screen can be slowed down, i.e. the open time in screen can be increased, by using the inventive printing pastes containing specific amounts of a polyurethane emulsion binder, a silicone and optionally further components, e.g. a crosslinking agent.
The invention thus concerns a process for printing textile fabrics characterised in that the fabrics are treated with a printing paste containing a polyurethane, a silicone, optionally a pigment, water and optionally further components.
The printing pastes used in the inventive process are a further part of the invention. They contain:
a) 5 to 25% by weight of a polyurethane,
b) 1.5 to 20% by weight of a silicone,
c) 0 to 50% by weight of a further component and
d) water as the remainder,
the sum of the amounts of components (a)+(b)+(c)+(d) being 100%.
Preferred printing pastes contain:
a) 10 to 20% by weight, in particular 14 to 18% by weight, of a polyurethane,
b) 2 to 15% by weight, in particular 2.5 to 5.0% by weight, of a silicone,
c) 1 to 40% by weight, in particular 5 to 38% by weight, of a further component and
d) water as the remainder.
The above % values refer to the pure amounts of urethane, silicone etc.
The polyurethanes are preferably used as stable aqueous polyurethane dispersions containing only small amounts (less than 3%) or no organic solvent.
In principle, all the well-known polyurethanes prepared by polyaddition of a di- or polyfunctional isocyanate and a di- or polyfunctional alcohol can be applied in the printing pastes according to the invention.
Preferably the polyurethanes are derived from aliphatic, cycloaliphatic, araliphatic or aromatic diisocyanates. Typical of such diisocyanate compounds are hexamethylene diisocyanate, biuret of hexamethylene diisocyanate, 2,2,4-trimethyl-hexamethylene diisocyanate, 1,4-diisocyanatocyclohexane, 4,4′-diisocyanatodicyclohexylmethane, isophorone diisocyanate, 1,3-cyclohexane bis(methylisocyanate), 1,4-diisocyanatobenzene, diphenylmethane diisocyanate in the form of its 2,2′-, 2,4′- and 4,4′-isomers, diisocyanatotoluene in the form of its 2,4- and 2,6-isomers and 1,5-diisocyanatonaphthalene.
The most preferred diisocyanates for the preparation of the polyurethanes suitable as component (a) are toluene diisocyanate, isophorone diisocyanate and, in particular, hexamethylene diisocyanate.
Di- or polyfunctional alcohols suitable for the preparation of polyurethanes are hydroxy-terminated polyethers and, in particular, hydroxy-terminated polyesters. Hydroxy-terminated polyesters can be prepared, for example, by the condensation of appropriate proportions of glycols and higher functionality polyols with dicarboxylic or polycarboxylic acids.
Some of the above urethanes and dispersions are commercially available.
Preferably, component (a) of the printing pastes according to the invention is an isocyanate-terminated reaction product of polyisocyanates and hydroxy-terminated polyesters, more specifically the polyaddition product of a diisocyanate and a polyester polyol produced by reacting a difunctional acid with an excess of a di- and/or tri-functional alcohol.
As the difunctional acid preferably succinic acid and especially adipic acid are used.
The di- and/or tri-functional alcohol may be an alkane diol or triol having 2 to 6 carbon atoms; these alcohols optionally can contain ether groups and/or can contain diamine components or polyether alcohols. All these compounds are well known in polyurethane chemistry. They are e.g. described in U.S. Pat. No. 5,961,906 in columns 1 and 2.
Preferably, the difunctional alcohol is ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, polyethylene glycol or polyproylene glycol.
Especially useful is the urethane having the trade name Dicrylan PMC.
The silicones also are preferably used as stable aqueous dispersions. Such silicones are known as polyorganosiloxanes and are commercially available.
Preferred silicones are amino-functional polydimethyl siloxane emulsions, especially those having the trade name ULTRATEX FEW or ULTRATEX UM.
Further components which may be present in the printing pastes are e.g. natural or synthetic thickeners, pigments, acids, bases and/or salts to adjust the pH to the desired value, anionic, nonio
Crabtree Alan
Lane Martin
Potts Ian George
Rouse Leslie Walter
Ciba Specialty Chemicals Corporation
Mansfield Kevin T.
Robertson Jeffrey B.
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