US2311850A - Flock printing - Google Patents

Description

Patented Feb. 23, 1943 FLOCK PRINTING Charles L. Mantell, Manhasset, N. Y., assignor to United Merchants & Manufacturers, Inc., New York, N. Y., a corporation of Delaware No Drawing. Application May 1, 1941,

Serial No. 391,348

This invention relates to relief printing on textiles and compositions adapted therefor, more particularly processes of flock printing and compositions adapted for use in such processes.

In relief or flock printing processes a textile is coated with an adhesive in a predetermined design as, for example, by employing a suitable stencil. In the flock printing process the coated textile is then treated with flock which adheres to and becomes anchored in the adhesive, the adhesive in turn adhering to and being anchored in the textile, and the thustreated textile is then subjected to treatment, as for example heating,

to set or dry the adhesive. It is necessary for a definite thickness of adhesive to be built-up above the surface of the fabric to provide the necessary relief effect, and in the case of flock printing the necessary anchorage for the flock. It is therefore necessary not only to coat the individual yarns or strands of the fabric but also to bridge across the space therebetween and in addition to build up a definite layer, coating or film, this necessary structure being commonly referred to as loft." In this and other respects the process and product is differentiated from the color printing of textiles, because in the latter process it is necessary to apply the desired color only to the individual yarns or threads and to avoid a continuous layer or film, particularly when the color is associated with an organic binder, because such film would make impossible the production of the necessary softness or hand.

The ideal adhesive for flock and relief printing is one which in its final form possesses not only the necessary loft but also the properties of flexibility, insolubility, and resistance to washing, ironing and dry cleaning to at least the same extent as that of the textile itself and preferably to a greater extent,'so that in effect the adhesive becomes a part of the textile. Color stability and economy in cost are other requirements of the ideal adhesive. Among these requirements loft and permanent flexibility are the most important characteristics, and by flexibility is meant that particular combination of flexibility, pliablity and softness which is so characteristic of textiles per se.

Adhesives formerly used in this art have been deficient in one or more of these requirements,

particularly the requirement of permanent flexibility and softness. The adhesive should be such that not only is it flexible when the print is first manufactured but also throughout the life of the print. Adhesives heretofore used have been subject to a number of disadvantages among the out- 3 Claims. (Cl. 117-13) peries and the like and subjected to sewing operations, the needles on the machines either failed to penetrate the portions of the design or else were broken during the sewing operation.

It is therefore an object of the present invention to provide an adhesive for flock printing and other relief printing processes meeting all of the above requirements.

In accordance with the present invention a per-' "manently flexible, oil modified alkyd resin of the heat-convertible, non-air-drying type is dispersed by means of a volatile dispersion medium. The resin of the present invention is one which is employed in the soluble or dispersible condition and capable of conversion into an insoluble and infusible condition by heating. After this condition has been attained it is permanently flexible and essentially stable in all respects and undergoes no further change on aging, including long continued exposure to the atmosphere. Such a resin may be obtained by reacting a polyhydric alcohol with a dibasic carboxylic acid and a fatty acid or mixture of fatty acids derived from a nondrying or semi-drying oil, so as to produce an oil modified alkyl resin capable of being converted or polymerized by heat to a condition of substantial insolubility, infusibility, permanent fiexibilty and softness and, ingeneral, chemical stability including resistance to color change and chemical change in general, on aging.

A resin of the type described may be referred to as one which is self-plasticized in that it contains in chemical combination a substance or radical Which acts as a primary plasticizing agent as, for example, a fatty acid, this self-plasticizing agent being one which acts as a permanent and stable plasticizer. In addition to this self-plasticiZing component the resin may be physically mixed with a separate and additional plasticizing component.

Preferably the resin used in preparing the adhesive is employed in a condition of intermediate polymerization which, however, is sufficiently advanced so that Whenthe adhesive is applied to the textile the operation of curing or converting by heat to the final condition will not require an undue length of time or temperatures higher than that which the fabric can undergo. For example, the stage of polymerization of the resin may be such that a percent by weight solutionof the resin in a volatile hydrocarbon such as petroleum or coal tar naphtha will yield a solution having a viscosity of about 25 centipoises or higher. In order to facilitate the application -of the resin to the textile it is necessary to disperse itin a volatile dispersion medium which can be eliminated during the heating of the tex-' tile to convert the adhesive, Such dispersion medium maybe a volatile solvent or Water, or an intimate mixture of the two. The dispersion may be of the water-in-oil type in which the resin or a solution of the resin in a volatile hydrophobe organic solvent constitutes the outer or continuous phase of an emulsion in which water is the inner phase. In such emulsion, as the ratio of inner to outer phase increases the viscosity increases until a critical point is reached beyond which inversion of the emulsion occurs from the water-in-oil to the oil-in-water type, and the proportion of phases may be so controlled that the composition of the emulsion corresponds approximately to that at the point of inversion which is about one part by weight of water to one part by weight of resin plus solvent (or resin alone). Lesser proportions of water may be employed provided the viscosity of the resulting emulsion is with n the range of flock printing consistency.

In order to secure a sufiicient thickness of deposit per unit area the dispersion must have a minimum concentration of total solids in any particular case, thi concentration varying with the particular fabric being printed. Generally his proportion is at least about 50 percent and may consist entirely of resin or binder. However, since such resin or binders are generally transparent, whereas flock printing generally requires an opaque or color deposit, the total solids preferably include a proportion of pigment which varies in different instances not only as to the proportion of the pigment but also as to its concentration by weight or volume.

It is unnecessary to describe in detail the specific nature of the pigments since they are known in the art. It is, however, necessary that the proportion of binder for a particular pigment or mixture of pigments be sufficient to bind the particles of pigment together, to cause sufiicient adherence of the deposit to the textile and sufficient anchorage for the flock, in the case of flock printing. Generally the proportion of binder should not be less than about 30 percent.

.In a typical case the resin is prepared as follows:

Example 1 Substantially 1.1 molecular weight of glycerine is reacted with 1.2 molecular weight of phthalic anhydride or phthalic anhydride and succinic anhydride with approximately 1 molecular weight or higher is obtained. The initial composition as above set fort-h corresponds to approximately 50 percent of fatty acids but after the reaction has been completed, due to the preferentially greater loss of glycerine and the dibasic acids as a result of volatilization a resin is produced which is of the order of greater than 50 percent combined fatty acids.

The proportion of self-plasticizing component embodied in the above example in the fatty acids of a non-drying or semi-drying oil varies somewhat with the nature of the dibasic carboxylic acid in order to obtain the desired degree of softness or flexibility of the resin in its final or heatconverted form. Where phthalic acid is used about 50 percent of said fatty acids is sufiicient for this purpose. With maleic acid a somewhat higher proportion of fatty acid may be used. With citric acid a somewhat lower proportion of fatty acid may be employed. The specific proportion of fatty acid to polyhydric alcohol and dibasic carboxylic acid may readily be determined by tests. Instead of glycerine other polyhydric alcoh may be employed.

It is not necessary to provide a multiplicity of examples since instructions to prepare an oilmodified alkyd re in of the non-air-drying heatconvertible type are sufficient to enable those skilled in the art to prepare such a resin. The invention is not in the resin per se but in its use as described and claimed. The resin prepared as described in the above example is one of numerous oil-modified alkyd resins which will provide a resin convertible by heat to a condition of infusibility and insolubility combined however, with sufiicient permanent softness and flexibilty to meet the requirements above mentioned. In addition such resin in the heat-converted form is particularly stable to washing, chemical change and aging and does not undergo a progressive solidification or hardening by the absorption of oxygen or other atmospheric influences such as sunlight. Such resin i also resistant to color changes.

In preparing the fiock printing composition, in a typical case, the following proportions may be employed: I

Example 2 Parts by weight Resin 37 Pigment 23 Water 40 The resin is melted or heated to reduce its viscosity and the Water is then gradually dispersed therein by the action of a high speed stirrer or other suitable mechanism. The pigment is then incorporated, again by the action of the high speed stirrer.

In another typical case ingredients are used in the following proportions:

Example 3 Parts by weight Resin 33 Solvent 9 Pigment 22 Water 36 The resin is dissolved in the solvent and the water incorporated in the same manner as above described. The pigments are then added and thoroughly incorporated. The resultant emulsion may be then adjusted by the addition of sufficient water or solvent or a combination of these to bring the product to a flock printing viscosity or consistency point.

Instead of employing the resin in the form of an emulsion it may be employed in the form of a solution in a volatile solvent for which the following represents a typical formula:

Example 4 Parts by weight Resin Solvent Pigment 25 The resin is dissolved in the solvent and the pigment then incorporated in the usual manner. In this particular case a resin is selected made in accordance with the above example in which, however, the degree of polymerization is carried to a stage where the solution of the resin in the solvent provides a solution having a viscosity of about 1000 centipoises.

In Example 2 the viscosity of the resulting emulsion is about 850 centipoises, and in Example 3 about 120 centipoises. In general, in order that-the dispersion of the present invention may be readily applied to textiles but nevertheless have a consistency such that suitably sharp definition may be obtained, the viscosity of the dispersion should be of the order of 100 to 1000 centipoises.

The prepared emulsion whose viscosity has been adjusted to fiockor relief-printing consistency is fed or delivered to the inside of a stencil in cylindrical form constituting a part of a suitable or conventional printing apparatus comprising said stencil and a rubber-covered roll, so that the textile fabric may be passed between the external cylindrical surfaces of the stencil and roll which functions to feed the textile against the stencil through the perforations of which -(constituting the design on the stencil) the emulsion is applied to the fabric-in said pre- I jected to an elevated temperature which may be of the order of F. to F. for a period from two to eightvhours in order to heat-set the adhesive, thereby causing adherence of the flock to the adhesive and the adhesive to the fabric particularly in the interstices on the fabric.

'After this operation the fabric is subjected to treatment whereby excess flock is removed.

I claim:

l Process of flock printing which comprises applying flock to a textile coated in a predetermined design with .an adhesive, said adhesive comprising a permanentlyfle'xible, oil-modified alkyd resin of the heat-convertible, non-airdrying type dispersed with a volatile dispersion medium, and heating the flock-coated textile to eliminate the dispersion medium and heat-set the resin.- 7

2. An improvement in the art of flock printing which comprises substituting for the adhesives heretofore used in the flock printing of textiles, an adhesive comprising a permanently flexible, oil-modified alkyd resin of the heat-convertible, non-air-drying type dispersed with a volatile dispersion medium, and heating the flock-coated textile to eliminate the dispersion medium and heat-set the resin.

3. A textile carrying thereon a flock print, said flock being carried by and united to the'textile by an adhesive comprising a permanently fl'exible, heat-set, oil-modified alkyd resin of the heat-convertible, non-aindrying type.

CHARLES L. MANTELL.