BACKGROUND OF THE INVENTION

Field of the Invention

The present invention is generally directed toward a pretreatment composition for use in connection with the application of sublimation ink transfer to a cotton-containing textile material, such as a T-shirt.

Description of the Prior Art

Ink or image transfer systems are useful in applying graphics to a wide variety of items. In certain applications, ink transfers have advantages over other types of image application systems, including direct printing systems. In some situations, the substrate or item intended to receive the image is not amenable to direct printing operations. In other situations, the volume of images to be printed makes direct printing operations, such as screen printing, economically unfeasible. The use of ink transfers also allows printing operations to be performed at a site remote from the products to which the images will be applied. The textile and clothing industry has used ink transfers as a way of applying an image to, for example, an article of clothing. U.S. Patent No. 8,815,040 is directed toward an ink transfer system for transferring ink images to synthetic textile materials.

Dye sublimation transfers have also been shown to provide certain benefits as compared to direct-to-substrate printing and other types of image transfer systems, particularly in regard to fabrics. Dye sublimation transfers are created by laying down reversed imagery onto transfer paper using dye-containing inks, as opposed to pigmented inks that are used in a number of direct printing systems. The fabric and transfer paper are pressed together under high heat, often 400°F, and the dyes contained within the inks flash sublimate. The vapor dyes then migrate into the fabric's fibers thereby transferring the image from the transfer to the fabric. Dye sublimation has the ability to provide vibrant colors and transfer of highly detailed images that are limited only by the texture of the fabric and the resolution of the printer used in the manufacture of the transfer.

However, dye sublimation has not been demonstrated to work well in all fabric applications. For example, while dye sublimation can be used on cotton-containing fabrics to initially transfer an image to the fabric, the dyes generally do not adhere well to the cotton fibers. As a result, the image is durable and degrades very quickly, even upon a single wash cycle. Therefore, there is a need in the art for a system that permits use of sublimation dye transfers with cotton-containing textile materials that are colorfast and hold up even under repeated washing cycles.

SUMMARY OF THE INVENTION

In certain embodiments of the present invention there is provided a method of transferring an ink image onto a cotton-containing textile material. An aqueous pretreatment composition is applied to at least a portion of the textile material that is to receive the ink image. The pretreatment composition comprises one or more polymer resins, one or more crosslinking compounds, and one or more plasticizers. The textile material containing the pretreatment composition is heated so as to remove moisture from the pretreatment composition and react the one or more polymer resins with the one or more crosslinking compounds thereby forming an image-receiving area on the textile material. The ink image is transferred to the textile material by positioning a sublimation transfer system in contact with at least a portion of the image-receiving area and heating the sublimation transfer system to a temperature sufficient to cause the gassing of at least a portion of one or more dyes contained within the ink image and the transfer of at least a portion of the gasified dyes to the image-receiving area.

In other embodiments of the present invention there is provided an aqueous composition for use with sublimation transfer systems on cotton-containing textile materials. The composition comprises from about 5% to about 30% by weight of one or more water-dispersible polymer resins, from about 0.25% to about 10% by weight of one or more melamine crosslinking agents, from about 0.5% to about 12% by weight of one or more plasticizers, and from about 50% to about 90% by weight of water.

In still other embodiments of the present invention there is provided a cotton- containing textile material having a quantity of the pretreatment composition described herein applied to at least an image-receiving area thereof. The textile material may further have an image applied to the image-receiving area using a dye sublimation transfer. DETAILED DESCRIPTION OF THE PREFERRED EMB ODEVIENT

Certain embodiments of the present pertain to an aqueous composition that can be applied to a textile material, especially a textile material comprising cotton fibers, and that provides a platform for transferring an image to the textile material from a dye sublimation transfer. The aqueous composition, when cured upon the textile material, bonds with the textile's fibers and provides a stable base for adhesion of the gasified dyes from the transfer.

In particular embodiments, the water-based composition comprises a combination of one or more water-dispersible polymer resins, one or more crosslinking agents, and glass particles, each of which is described in further detail below. Generally, the one or more polymer resins comprise at least one member selected from the group consisting of polyesters, urethanes, epoxies, acrylics and latexes. However, in preferred embodiments, the one or more polymer resins comprise at least one polyester resin. Even more preferably, the polyester resin comprises a polyester-polyurethane resin. Exemplary polymer resins that may be used with the present invention include Alberdingk Boley U 199 (60% solids, pH between 7.5-9.5, Brookfield viscosity 200-1000 mPas), Alberdink Boley U 475 (40% solids, pH between 7.5-8.5, Brookfield viscosity 50-300 mPas), and Dispercoll U 53 (40% solids, viscosity at 23°C, spindle L 21 30 rpm 50-600 mPas). In certain embodiments, the composition comprises from about 5% to about 30% by weight, from about 10% to about 20% by weight, or from about 12% to about 18% by weight of the one or more water-dispersible polymer resins. It is noted that, often, the one or more polymer resins are formulated as water-based dispersion. Therefore, the foregoing amounts are considered to be on a percent solids basis.

In certain embodiments, the one or more crosslinking agents comprise at least one crosslinking agent selected from the group consisting of melamine crosslinking agents and aziridine crosslinking agents. In preferred embodiments, the melamine crosslinking agent comprises an alkylated melamine-formaldehyde resin. Exemplary crosslinking agents that may be used with the present invention include Cymel 327 (a methylated high imino melamine crosslinker, 90% solids) and CX-100 by DSM (a polyfunctional aziridine crosslinker, 100%) solids). In certain embodiments, the one or more crosslinking agents, and particular the melamine crosslinking agents, are formulated with isobutanol. In certain embodiments, the composition comprises from about 0.25% to about 10% by weight, from about 0.5% to about 5% by weight, or from about 1% to about 4% by weight of the one or more crosslinking agents.

The glass particles, which comprise the composition, are believed to improve the crosslinking density of the composition upon curing thereof. In addition, the glass particles are believed to promote the adhesion of the composition to the fibers of the textile material. The glass particles may also function as a high-grade filler material for the composition. In particular embodiments, the glass particles comprise glass microspheres that have an average particle size of from about 7 to about 10 μπι. One exemplary type of glass microspheres that may be used with the present invention is Spheriglass ^® 5000 Solid Glass Spheres by Potter Industries. In certain embodiments, the composition comprises from about 0.25%) to about 10%> by weight, from about 0.5% to about 5% by weight, or from about 1%) to about 3% of the glass particles.

The glass particles aid in allowing the sublimation dye transfer to achieve very fine detail upon sublimation and absorption into the textile material. The glass particles help to eliminate "halos" surrounding the image that can be formed during the sublimation process, which are the result of bleeding of the image beyond its original margins. In addition, because at least a portion of the gassed dye penetrates or is absorbed by the glass particles, wash resistance and abrasion resistance is improved. Moreover, the glass particles reduce and/or eliminate image shrinkage and provide improved stress distribution.

Certain embodiments of the present invention further comprise a silica material. Exemplary silica materials for use with the present invention include Evonik TS-100 (untreated thermal silica) and Evonik Aerosil 200 (hydrophilic fumed silica). In particular embodiments, the silica material assists with suspending the glass particles within the composition thereby permitting the composition to be sprayed or otherwise applied to a textile material without particle settling issues. In certain embodiments, the composition comprises from about 0.25% to about 10% by weight, from about 0.5% to about 5%, or from about 1% to about 3% by weight of the silica material.

Certain embodiments of the present invention further comprise at least one plasticizer. In particular embodiments, the plasticizer comprises a benzoic acid ester, such as dipropylene glycol dibenzoate, diethylene glycol dibenzoate, or a mixture thereof. An exemplary plasticizer that may be used with the present invention is Benzoflex 50 by Eastman Chemical. In certain embodiments, the plasticizer may impart improved hand- feel to the textile material bearing the composition, and may improve the washability of image-bearing textile material by enhancing color retention. In certain embodiments, the composition comprises from about 0.5% to about 12% by weight, from about 1% to about 10%) by weight, or from about 2.5% to about 7.5% by weight of the at least one plasticizer.

As discussed above, the compositions according to the present invention are water- based. In certain embodiments, the compositions comprise from about 50% to about 90% by weight, from about 60% to about 80% by weight, or from about 65% to about 75% by weight of water. As certain components, such as the polymer resins, may be supplied as aqueous dispersions, these ranges refer to the total weight of water including the water contained in these dispersions as well as water (e.g., deionized water) that is separately added.

The compositions disclosed herein are useful in methods of transferring an ink image onto a cotton-containing textile material. In these embodiments, the compositions are used as a textile pretreatment formulation. The pretreatment composition is applied to a portion of the textile material that is designed to ultimately receive the image transfer. Alternatively, and particularly if the dimensions of the sublimation transfer are not known, the pretreatment composition can be applied to substantially all of the textile material. In certain embodiments, the pretreatment composition is applied to the textile material in an amount of from about 0.05 to about 1 g/in ² , from about 0.1 to about 0.8 g/in ² , or from about 0.2 to about 0.5 g/in ² . The pretreatment composition can be applied to the textile material by nearly any means known in the art. However, in certain embodiments, it is preferable to apply the pretreatment composition by spraying or inkjetting the pretreatment composition onto the textile material.

The textile material comprising the wet pretreatment composition is then heated so as to remove moisture from the pretreatment composition and react the one or more polymer resins with the one or more crosslinking compounds thereby forming an image- receiving area on the textile material. In certain embodiments, this heating step may comprise passing the pretreated textile material through a drying oven or other similar apparatus and heating the textile material to a temperature of at least 275°F. In particular embodiments, the textile material is heated to a temperature of between about 275°F to about 400°F, from about 300°F to about 375°F, or from about 325°F to about 350°F. The heating, or drying, time over which the textile material is exposed to the elevated temperature conditions depends at least in part on the drying temperature. However, in certain embodiments, the drying time is at least 30 seconds, or can range from about 30 seconds to about 5 minutes, from about 45 seconds to about 2 minutes, or from about 60 to about 90 seconds. In certain embodiments, this heating step may be accomplished through the use of a heated press. Not only does the press provide the heat required to remove moisture from and crosslink the pretreatment composition, oxygen is also kept away from the reaction. This helps eliminate oxygen inhibition of the reaction between the polymer resin and crosslinking agent, which otherwise might retard the crosslinking cycle.

Once the pretreatment composition has been adequately dried and/or reacted on the textile material, the image can now be applied to the image-receiving area. In this process, a sublimation transfer system is placed in contact with at least a portion of the image- receiving area. Heat is then applied to the sublimation transfer system, and consequently the textile material, so as to raise the temperature of the sublimation transfer system to a level sufficient to cause the gassing of at least a portion of the one or more dyes contained within the ink image. In certain embodiments, the heat is supplied by a heated press, which can be in the form of a heated plate or pair of opposed rollers through which the textile material and transfer system are directed. The application of pressure to the transfer system and textile material allows the gasified dyes to migrate into the image-receiving area of the textile material thereby transferring the image from the transfer system to the textile material. In certain embodiments, this step of transferring the ink image to the textile material comprises heating the sublimation transfer system to a temperature of at least 300°F, and alternatively to a temperature of from about 300°F to about 425°F, from about 325°F to about 400°F, or from about 350°F to about 375°F. Again, the heating time is dependent, at least in part, upon the heating temperature. However, in certain embodiments, the heating time for this transfer step is at least 15 seconds, and alternatively from about 15 seconds to about 2 minutes, from about 30 seconds to about 90 seconds, or from about 45 seconds to about 60 seconds.

In certain embodiments, it is important to note that because of the pretreatment composition, the dye does not penetrate deeply into the fibers making up the textile material. The dyes tend to remain on top of the fibers thereby leading to transferred images that are very crisp and vibrant.

The finished textile product comprises an image formed within the image-receiving area comprising the dye of one or more sublimation inks. As noted above, in certain embodiments of the present invention, the textile material comprises cotton fibers. In particular embodiments, the textile material may be a blend of cotton and one or more synthetic fibers, such as polyester, nylon, or rayon. In these embodiments, the textile material may comprise at least 50% cotton, at least 75% cotton, or at least 90% cotton, on the basis of total fiber content. Alternatively, the textile material may be substantially 100%) cotton. In certain embodiments, the textile material is provided in the form of an article of clothing, such as a T-shirt. The textile material can also have been dyed or colored prior to the pretreatment process. Alternatively, the textile material can be provided as a continuous web of material, such as in the form of a roll, or in the form of a banner or other type of signage-quality material.

In certain embodiments, the finished textile product exhibits excellent washability characteristics, capable of withstanding a minimum of six washing cycles (e.g., using a household washing machine and detergent) without any observable fading of the transferred image. In other embodiments, the finished product is capable of withstanding at least ten, at least 15, or at least 25 washing cycles while still exhibiting only minor amounts of fading of the transferred image. The image remaining after the washing cycles is considered industrially acceptable and retains at least 50%, at least 70%, at least 75% or at least 80% of the original color density as measured by a spectrodensitometer, even after 10, 15, or 25 washing cycles. In addition, the pretreatment composition avoids discernable yellowing of the textile material upon heating and curing of the composition. Use of the pretreatment composition also avoids the need to overcoat the transferred image with any kind of protective coating.

EXAMPLES

The following table contains exemplary pretreatment compositions made in accordance with the present invention. These formulations are provided by way of illustration and should not be taken as limiting the scope of the present invention.

Deionized water 64.50 62.7 70.5

In order to test the washability of an image transferred to 100% cotton fabric using a pretreatment composition according to the present invention, Formulation 1 was applied to a cotton swatch at a rate 0.3g/in ² and dried to form an image-receiving area. Next, a sublimation dye transfer was placed in contact with the image-receiving area and pressed under heat so as to transfer the ink image onto the cotton swatch. The image contained several colors, the strength was measured using an XRite 528 spectrodensitometer. The cotton swatch was washed 25 times in a conventional household washing machine with a conventional laundry detergent. The color strength of each color was measured again and the percent loss of color strength calculated. The results are provided in the table below.