US2222581A - Textile printing paste - Google Patents

Description

Patented Nov. 19, 1940 STA'ES .GFFEQE TEXTILE PRINTING PASTE corporation of Ohio No Drawing.

Application June 22, 1939,

Serial No. 280,517

3 Claims.

This invention relates to textile printing pastes useful in marking textile fabrics, and designed to be applied to fabric by intaglio rollers like the dye pastes heretofore used for decorat- 5 ing fabrics.

Conventional textile printing is ordinaril done with water solutions of dyestufls containing water soluble thickening agents in suflicient quantity to retard the spreading of the color on the fabric after printing. The dyestufi is fixed onto the fabric by some chemical process and the thickening agent is then washed out of the fabric. The time and expense involved in this after treatment, added to the originally high color cost for light and tub-fast dyes, has been a major problem in textile printing. An unsolved problem has been the reproduction of very fine designs. Since the pastes spread on the fabric after printing when thin enough to be removed sharply from fine engravings, giving blurred designs, it has been found impossible to use photogravure cylinders or extremely fine mill and dye engravings. Attempts to modify these pastes by addition of wetting agents and emulsiflcation of oils therein have not solved the basic dimculties.

The use as printing pastes of colored lacquers (which, for the purpose of this application are defined as dispersions of color in vehicles consisting of a solution of a plastic or solid film forming, water resistant binder such as a cellulose derivative or a resin, in an organic solvent or mixture of solvents) has been attempted in order to overcome the difliculties with prior art pastes, but has not been successful commercially. Relatively few lacquer compositions withstand both dry cleaning and washing; and such compositions as are resistant have been generally unacceptable due to the fact that the fabrics, when printed with these lacquers, develop an undesirable stiff feel (known to the trade as hand) to the necessity for using large amounts of color to obtain deep shades, and to the tendency of colored markings to rub off onto other clothing and leave a mark (known as "crocking).

I have invented a new type of textile printing paste which eliminates the disadvantages of the conventional dye printing pastes and avoids the difliculties which have been encountered in the prior art lacquer printing pastes. My new pastes are emulsions in which an outer continuous water-immiscible-lacquer phase is thickened by an inner aqueous phase which is at least 20 per cent. of the total emulsion, by weight. Preferably, the binder of the lacquer is one which is originally soluble in ordinary organic solvents and which can be converted into an insoluble state after printing-most desirably, a readily heat-polymerizable synthetic resin, best exemplified by the plasticized urea formaldehyde resins.

The use of pastes made in accordance with my invention permits of the use of cheap pigments and avoids the after treatment necessary with conventional printing pastes. Furthermore, my new pastes separate sharpl even from very fine photogravure cylinders, although thickened sufliciently to prevent any spreading on the fab ric; this makes possible much finer printing than can be obtained with conventional pastes. The hand imparted to fabrics by my new pastes is very much less than the hand imparted to similar fabrics by ordinary lacquer pastes having the same binder, the amount of color needed to produce deep shades is sharply reduced, and the cracking substantially eliminated.

I believe that the improved results obtained with my pastes are due to the fact that the color does not penetrate into the fabric or spread laterally on the fabric, so that the bulk of the color remains visible, cemented by binder to the structural fibres of the individual yarns of the fabric, as discontinuous markings at or near the surface of the fabric. Thus, the excessive cementing of fibres and yarns, and the dilution of pigment value characteristic of ordinary lacquer pastes, are both avoided, and hand, pigment cost and crocking are sharply reduced.

A further advantage of my invention lies in the fact that the use of water to thicken the lacquer sharply reduces the amount of binder required as well as the amount of pigment, so that excessive hand imparted by mere added weight is avoided. In general, I prefer to maintain the binder content at not above 25%, to minimize weighting of the fabric, and to maintain the volume ratio of binder to pigment at 2 to 1 or higher, to minimize crocking. Although good results are obtainable with 20% water, I prefer to operate in the range of 40 to water content. Larger amounts can be added if desired, but care must be taken not to add so much water that the emulsion breaks during application.

Still another advantage of the use of these emulsions lies in the fact that the body can be varied readily by varying the ratio of water to organic solvents. This permits ready reproduction of desired body with different lacquers and with different pigments.

A typical example of my invention is as follows:

A printing paste is prepared as follows:

and stirred into the lacquer phase in a turbo mixer at a relatively high speed, and the mix is then passed through a colloid mill or homogenizer.

The resultant emulsion, although it contains only 22% solids, has a consistency like that of the conventional dye-pastes used for textile printing-that of a rather soft cold cream. When applied to water absorbent fabrics with the conventional intaglio rollers used for printing fabric with dye pastes, a discontinuous, nonpenetrating film is obtained which is unusually flexible, soft and uniform, and has high color value. Because of the consistency of the emulsion, the film produced does not completely surround the individual fibers, but is confined largely to the portions of thefibers adjacent the printed side. In order to develop maximum resistance to washing and dry cleaning in this type of paste containing a heat convertible resin, the fabric should be heated to set the resin. This may be done by passing the fabric over the conventional heating drums used in textile plants, at a tem perature of 250 to 300 F.

Some pigments suchasthe light chrome yellows and certain organic lakes precipitated on alumina hydrate tend to cause breaking of the emulsions. I find that this may be corrected by the inclusion of small percentages of colloidal clay, such as bentonite; these additions tend to stabilize the emulsions.

While stable emulsions can be made in a mixer alone, the use of a colloid mill gives a smoother, more desirable product. Where hydrophobe binders are used, while it is preferable to add the water to the lacquer phase, the order may be reversed; in such event, precipitation occurs initially, until sufflcient laquer is added, when the lacquer coalesces to form a continuous phase.

It will be noted that in the foregoing example the binder of the lacquer includes, in addition to the urea resin, a soft material compatible therewith, which serves to plasticize the urea resin, so that the binder may most simply be described as consisting of a plasticized urea resin.

My invention, while it is of special value with respect to the production of permanent prints on fabric, may also be used for cheaper work, where prior art lacquer prints have been too expensive, by using pastes with very small percentages of pigment and binder. Such low solid emulsions, when made with flexible film forming ingredients as described in the example, are highly desirable in the printing of very sheer fabrics.

Printing pastes made from any water-insoluble resins which may be rapidly converted to films which have the desired resistance to washing and/or dry cleaning may be used to produce water-in-lacqueremulsions for the best textile printing. While plasticized urea formaldehyde resins gave the most satisfactory results, some phenolic resins, and some drying oil modified alkyd resins, have proven acceptable. These are resins of the class specified as preferable and most desirable on page 1, namely, readily heatpolymerizable synthetic resins which can be converted into an insoluble state after printing by heat-polymerization. These resins may be plas- -ticized, as with fatty oils, the various chemical plasticizers which are water immiscible, and with alkyd resins. Practically all pigments may be used, including metallic pigments previously dispersed in hydrophobe solvents.

In the use of my printing pastes, I prefer to heat the printed cloth to a degree sufiiclent to convert the resinous binder used to the insoluble state.

This application is a continuation in part of my co-pending application Serial Number 182,- 795, filed December 31, 1937.

The improvement in the art of textile printing, which consists in thickening the colors printed on absorbent textile by emulsification instead of by the incorporationof a solid thickener, is not claimed herein as it forms the subject matter of my co-pendingdivisionalapplication Serial Number 314,868, filed January 20, 1940.

I claim:

1. A textile printing paste consisting of an emulsion having an outer continuous water-immiscible-lacquer phase consisting of thin pigmented lacquer containing a binder amounting to at least twice the amount of pigment by volume and including a readily heat-polymerizable synthetic resin which can be converted into an insoluble state by heating after printing, and thickened to printing consistency by an inner aqueous phase amounting to at least 20% of the total emulsion, by weight.

2. A textile printing paste consisting of an emulsion having an outer continuous water-immiscible-lacquer phase consisting of thin pigmented lacquer composed of a plasticized urea formaldehyde resin in the organic-solvent-soluble state dissolved in a volatile water-immiscible organic solvent and amounting to at least twice the amount of pigment, by volume, and thickened to printing consistency by an inner aqueous phase amounting to at least 20% of the total emulsion, by weight.

3. A textile printing paste consisting of an emulsion having an outer continuous water-immiscible-lacquer phase consisting of thin pigmented lacquer composed of a urea formaldehyde resin in the organic-solvent-soluble state and a soft oil-modified alkyd resin, both dissolved in a volatile water-immiscible organic solvent' and amounting together to at least twice the amount of pigment, by volume, and thickened to printing consistency by an aqueous inner phase amounting to at least 20% of the total emulsion, by 7 weight.

HENRY JENEI'I.