WO2021173301A2

WO2021173301A2 - Heat transfer label and process for the use thereof

Info

Publication number: WO2021173301A2
Application number: PCT/US2021/015702
Authority: WO
Inventors: Michael B. Colella; Huanyu Wei; Caroline M. O'LEARY
Original assignee: Illinois Tool Works Inc.
Priority date: 2020-02-27
Filing date: 2021-01-29
Publication date: 2021-09-02
Also published as: WO2021173301A3

Abstract

A DWR heat transfer label is provided for application to an item or fabric that is a durable water repellent (DWR) based substrate. The heat transfer label includes a carrier web, one or more ink layers that define a graphic supported on the carrier web, and at least one adhesive layer adapted to bond to the DWR substrate that is based on an acrylic or urethane composition devoid of polyester and polyamide. The DWR heat transfer label may be applied to a substrate by a heat transfer method. An adhesive formulation based on an acrylic composition is also disclosed.

Description

HEAT TRANSFER LABEL AND PROCESS FOR THE USE THEREOF

RELATED APPLICATIONS

[0001] This application claims priority of United States Provisional Patent Application Serial Nos. 62/982,174 and 63/053,170 filed February 27, 2020 and July 17, 2020, respectively; the contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

[0002] The present invention in general relates to heat transfer labels, and in particular to heat transfer labels for application of indicia to durable water repellant fabrics.

BACKGROUND OF THE INVENTION

[0003] Durable water repellent (DWR) is a term conventionally used to describe a coating added to fabrics at the factory to make fabrics water-resistant (hydrophobic). Most factory applied DWR treatments are fluoropolymer based. Durable water repellents are commonly used in conjunction with waterproof breathable fabrics such as stretched polytetrafluoroethylene to prevent the outer layer of fabric from becoming saturated with water. This saturation, called 'wetting out,' can reduce the garment's breathability (moisture transport through the breathable membrane) and let water through.

[0004] Heat transfer labels, commonly known as "tag- less tags", are used to promote a brand of a garment or fabric, or to provide care instructions without the bulk of a traditional woven or printed label. Heat transfer labels are applied directly onto the garment, tag-free. Heat transfer labels stretch with the fabric, are soft to the touch, and are applied with a heat pre . [0005] Heat transfer labels are in widespread use in the textile industry. For example, heat transfer labels are used to transfer indicia formed from ink onto many fabrics for cleaning instmctions, sizes, fabric composition, and decoration, etc. Heat transfer labels are also used in the automotive industry; in particular the safety warning labels on seat belts and sun visors made of various fabric compositions which may be colored through the use of sublimation dyes. Typically, heat transfer labels include thermoplastic inks and/or adhesives that are heat-activated to adhere to fabrics. Heat transfer labels have replaced sewn-on patches in many fabric applications, especially for sports apparel, tee shirts and under garments.

[0006] FIG. 1 illustrates the construction for a prior art heat transfer label 10 used in the apparel industry. An inert carrier web 12 is coated with a release layer 14 upon which a graphic image 16 is routinely printed. The inert carrier web 12 is formed of a material illustratively including polyester, polylactic acid, poly (lactic-co-gly colic acid), polycaprolactone, poly a-hydroxy esters, and laminates containing any of the aforementioned. The inert carrier web 12 typically has a thickness of 5 to 500 microns. This graphic image 16 can be a single pass of one color or several passes of multiple colors. In some instances, there may even be multiple passes of the same color. For illustrative simplicity, the graphic image 16 is shown as a single layer. In most cases the graphic image 16 is backed with a pass of a white ink as a backup layer 18. The white backup layer 18 is used to ensure the colors in the graphic image remain as intended even if the colors are being applied to a darker color or multi-color fabrics. The dye migration layer 20 is commonly an ink containing activated carbon which acts as a filter for sublimation dye molecules by absorbing them as they migrate into the layer 20. This migration resistant layer 20 is often formed with multiple passes with a second dye migration layer 20’ shown in FIG. 1, or even more depending upon how aggressive the sublimation dye is and how effective at absorbing the sublimation dye the activated carbon is. An adhesive is also printed in multiple passes as shown in FIG. 1 as a two-pass stmcture 22 and 22’. The adhesive being polyester, polyurethane, polyamide, or a combination thereof. The label 10 is transferred to the fabric substrate 24 through the application of heat 26 and pressure 28 from the backside of the carrier web 12. After bonding to the fabric 24, the carrier web 12 and the release layer 14 are peeled away and discarded, leaving the image 16 visible on the substrate 24. Tetrault et. al. (US Patent No. 9,944,424 B2) have taught us that another approach to minimizing dye migration into the label is to have the heat source below the garment. In this manner the sublimation dyes are attracted to the heat source which is away from the label.

[0007] DWR fabrics are by their construction resistant to heat transfer labels adhering well to them. DWR fabrics have in the past been produced by impregnating fabrics with water resistant poly(fluorocarbons) - PFCs and used herein this refers to both per- and poly- fluorinated chemicals. Like their silicone analogs these PFCs have a low surface tension and are very difficult for inks and adhesives typically used in heat transfer labels to wet out. This poor wetting results in poor adhesion and unacceptable durability of the heat transferred label. While PFCs are being phased out of DWR fabrics, in many instances PFCs are being replaced by special acrylic and urethane polymers that still possess the characteristics of being water repellent. These acrylic and urethane polymers still have low surface tensions and the problem of wetting these materials out with heat transfer label adhesive formulations persist. While such compositions have been used as a textile fiber treatment, heat transfer label applications have remained problematic. In some cases apparel manufacturers have had to resort to sewn on labels which compromise the water repellency of the garment.

[0008] Thus, there exists a need for a high quality heat transfer label that will transfer and adhere strongly to the new generation of DWR fabrics, especially those based on acrylic or urethane polymers. There further exists a need for heat transfer labels that are durable enough to withstand repeated washings of the garment at high temperatures, as well as being rub resistant to the outdoor “wear and tear” these labels are typically exposed to. There further exists a need for a label that is easily made (e.g., printed), using readily commercially available materials. There further exists a need for raw materials used to make the indicia that are approved for use on fabrics. There further exists a need for a label that is stable and has a prolonged shelf life.

SUMMARY OF THE INVENTION

[0009] A DWR heat transfer label is provided for application to an item or fabric that is a durable water repellent (DWR) based substrate. The heat transfer label includes a carrier web, one or more ink layers that define a graphic supported on the carrier web, and at least one adhesive layer adapted to bond to the DWR substrate that is based on acrylic or urethane compositions devoid of polyester and polyamide. The DWR heat transfer label may be applied to a substrate by a heat transfer method. An adhesive formulation based on an acrylic composition is also disclosed.

[0010] A method for imparting a label to a substrate includes positioning a heat transfer label on the substrate. Heat and pressure are applied to the label from a backside of the carrier web to bond the graphic to the substrate. The carrier web is positioned to expose the graphic on the substrate.

[0011] An adhesive formulation includes acrylic or urethane composition with a molecular weight of between 2000 and 100,000. The acrylic composition is obtained by the polymerization of: 65 to 95% by weight of alkyl acrylates, cycloalkyl acrylates, arylacrylates, or a combination thereof. 0 to 20% by weight of acrylic acid is also present. A remainder by weight of at least one ester of mono- or di- (Ci-Cs alkyl) a- or b-ethylenically unsaturated dicarboxylic acid is also present. The urethane composition is present as an oil in water emulsion. The acrylic or urethane composition is present as an oil in water emulsion and forming a majority by weight of the formulation. An additive of a rheology modifier, a defoamer, a matting agent, or a combination thereof is also optionally present. The additive or the combination of additives forming a minority by weight of the formulation.

BRIEF DESCRIPTION OF THE DRAWINGS [0012] The subject matter that is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other objects, features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

[0013] FIG. 1 illustrates the construction for a standard prior art heat transfer label used in the apparel industry;

[0014] FIG. 2 illustrates the construction of a heat transfer label for application to various durable water repellent (DWR) items or fabrics-based substrates in accordance with an embodiment of the present invention; and

[0015] FIG. 3 illustrates the construction of a heat transfer label for application to various durable water repellent (DWR) items or fabrics-based substrates that do not require a dye migration resistant layer in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION [0016] The present invention has utility as a heat transfer label for application to various durable water repellent (DWR) items or fabrics based substrates. Embodiments of the inventive heat transfer label reduce the wetting out problem of conventional DWR coatings associated with their low surface energy. In contrast to the prior art adhesives of polyester, and polyamide; the present invention resorts to an acrylic adhesive that is able to adhere well to the DWR coatings and provides a durable heat transfer label that is easy to produce and apply.

[0017] Inventive embodiments of the DWR heat transfer label include a carrier web, one or more ink layers to define the graphic, optionally a dye migration barrier layer, and an adhesive layer or layers as required. In some inventive embodiments, a release coat is applied to the carrier web. The inks, barrier layer, and adhesive are printed and cured to form a storable film on the carrier web.

[0018] As used herein, “curing” is defined as the drying of solvent-based or water-based ink to drive off the solvent and/or water. Inventive embodiments of the DWR heat transfer label may be applied to a substrate by a heat transfer process, illustratively including manual and automatic clam shell heat presses, vertical heat transfer presses as well as roll-on heat transfer presses as offered, for example, by Insta Graphic Systems and United Silicone. The temporary carrier web is removed after the indicia of the label are transferred to the substrate. A method of making embodiments of the DWR heat transfer labels and a method of marking an item with indicia from a hot stamp label are also disclosed.

[0019] Embodiments of the inventive heat transfer label adhere strongly to the new generation of DWR fabrics, especially those based on acrylic polymers. It is appreciated that embodiments of the heat transfer labels may also adhere to non-DWR fabrics illustratively including synthetic fabrics such as polyester and nylon, as well as natural fiber-based fabrics such as cotton. The heat transfer labels are durable enough to withstand repeated high temperature washings of garments to which they are applied, as well as being rub resistant to the outdoor “wear and tear” these labels are typically exposed to. Embodiments of the heat transfer label are easily made (e.g., printed), using readily commercially available material . Raw materials used to make the indicia are approved for use on fabrics. Embodiments of the heat transfer label are chemically stable and have a prolonged shelf life. [0020] Specific inventive embodiments of the heat transfer label eliminate the use of hot melt particles in the inventive adhesive formulations. The typical adhesive used for apparel heat transfer labels contains insoluble hot melt particles scattered throughout the adhesive. The conventional use of hot melt particles is detailed in U.S. Patent Publication 2011/0226414A1. When melted to facilitate the heat transfer process the resultant “glue” is a hazy mixture of carrier resin and hot melt polymer. For printing reasons the adhesive is printed larger than the graphic resulting in a glue line halo around the image. This glue line halo is objectionable from an aesthetic point of view and in some cases label manufacturers have resorted to laser cutting the heat transfer label to eliminate the glue line halo. This is an added step in the manufacturing process and adds cost to the label. In inventive embodiments of the heat transfer label, since the adhesive formulations act alone without the need for a hot melt powder, the glue line is much more transparent and less likely to cause an objectionable halo around the image.

[0021] It is to be understood that in instances where a range of values are provided that the range is intended to encompass not only the end point values of the range but also intermediate values of the range as explicitly being included within the range and varying by the last significant figure of the range. By way of example, a recited range of from 1 to 4 is intended to include 1-2, 1-3, 2-4, 3-4, and 1-4.

[0022] Referring now to the figures, FIG. 2 shows the construction for an embodiment of a heat transfer label 30 for a DWR treated substrate in which like reference numerals having the meanings ascribed thereto with respect to the aforementioned FIG. 1. An inert carrier web 12 is coated with a release layer 14 upon which is printed a graphic image 16. This graphic image may be a single pass of one color or several passes of multiple colors. In some instances, there may even be multiple passes of the same color. For illustrative simplicity, the graphic image 16 is shown as a single layer. In most cases the graphic image 16 is backed with a pass of a white ink as a backup layer 18. The white backup layer 18 is used to ensure the colors in the graphic image remain as intended even if they are being applied to darker color or multi-color fabrics. The dye migration layer 20 is commonly an ink containing activated carbon which acts as a filter for sublimation dye molecules by absorbing the molecules as they migrate into the layer. This migration resistant layer 20 is often formed by multiple passes rather than just the one as shown in FIG. 2, depending upon how aggressive the sublimation dye is and how effective at absorbing the sublimation dye the activated carbon is. Embodiments of the inventive adhesive 32 are printed in a single pass or formed multiple passes to include a second adhesive layer 32’ as shown in FIG. 2. It is appreciated still more than two passes may be used to print the adhesive in inventive embodiments. Rather than the typical polyester, or polyamide compositions routinely used in the adhesive layer(s) 22 and 22’ per FIG. 1, adhesives 32 and 32’ are acrylics or oil in water urethane emulsions. In some inventive embodiments, the acrylics or urethanes are those employed to impart water repellency to the garment either as a pretreatment to the fabric 24 or after DWR application. The inventive label 30 is transferred to the fabric substrate 24 through the application of heat 26’ and pressure 28’ from the backside of the carrier. Typical application conditions for bonding as to heat 26’ and pressure 28’ include temperatures of between 80 and 200°C, pressures of from 01 to 20 bar, and dwell times of from 1 to 120 seconds. After bonding to the fabric substrate 24, the carrier web 12 is peeled away and the release layer 14 are peeled away and discarded, leaving the image 16 on the substrate 24. In still other inventive embodiments, the release layer 14 is retained when the web carrier 12 is peeled away and serves as a protective layer overlying the graphics 16. It is appreciated that in some inventive embodiments, when a protective coating is desired, the protective coating is added as a separate layer after the release coat. Typically, the release coat is the layer that something releases from, not that releases with an underlying layer. [0023] FIG. 3 shows the construction for another embodiment of an inventive heat transfer label 40 for a DWR treated substrate in which like reference numerals having the meanings ascribed thereto with respect to the aforementioned drawings. In this specific inventive embodiment, the DWR garment does not require a dye migration resistant layer 20 found in FIGs. 1 and 2. An inert carrier web 12 is coated with a release layer 14 upon which is printed a graphic image 16. This graphic image 16 may be a single pass of one color or several passes of multiple colors. In some instances, there may even be multiple passes of the same color. For illustrative simplicity, the graphic image is shown as one layer. In this specific inventive embodiment, the graphic image 16 is backed with one or more passes of a white ink backup layer 18 followed by an adhesive pass 32 of the present invention. Embodiments of the inventive adhesive 32 are printed in a single pass or formed with multiple passes to include a second adhesive layer 32’ as shown in FIG. 2. It is appreciated still more than two passes may be used to print the adhesive in inventive embodiments. The label 40 is transferred to the fabric substrate 24 through the application of heat 26’ and pressure 28’ from the backside of the carrier. After bonding to the fabric substrate 24, the carrier web 12 is peeled away and discarded leaving the image 16 on the substrate 24.

[0024] An adhesive operative herein to form layers 32 alone or in combination with 32’ include a polymer soluble in organic media with a molecular weight of between 2000 and 100,000. The adhesive being an acrylic composition obtained by polymerization of: 65 to 95% by weight of at least one acrylate of alkyl acrylates, cycloalkyl acrylates, arylacrylates, or a combination thereof; 0 to 20% by weight of acrylic acid; and a remainder by weight of at least one ester of mono- or di- (Ci-Cs alkyl) a- or b-ethylenically unsaturated dicarboxylic acid. In other inventive embodiments, the acrylic composition is a copolymer of styrene and an acrylic ester, the acrylic ester having a C1-C3 alkyl group atoms or being a C6-C12 aromatic acrylic ester. [0025] As used herein, the term “styrene” refers to styrene per se, as well as styrene containing modifications, such as a-methyl styrene, 3-chlorostyrene, 2,5-dichlorostyrene, 4- bromostyrene, 4-tert-butylstyrene, 4-methoxystyrene, vinyl naphthalene, vinyl toluene, and divinyl benzene.

[0026] The acrylic ester monomers are used in the copolymer of the present invention in amounts of greater than 30 weight percent. In another embodiment, the amount of acrylic ester monomer is from 30 to 85 weight percent based on the amount of monomers in the copolymer. Exemplary acrylic esters operative herein include methyl acrylate, ethyl acrylate and benzyl acrylate.

[0027] The styrene is present in amounts greater than about 15 weight percent based on the amount of monomers. In other inventive embodiments, the amount of styrene is from about 15 to about 70 weight percent based on the total weight of the copolymer.

[0028] The copolymer in some inventive embodiments includes a lesser amount of one or more additional monomers such that the copolymer contains at least 90 weight percent of styrene or acrylic or methacrylic monomers. The copolymer in such embodiments up to 10 weight percent of other monomers. Suitable monomers operative herein illustratively include vinyl esters of aliphatic acids, ethylenically unsaturated carboxylic acids, and combinations thereof. Ethylenically unsaturated carboxylic acids operative herein illustratively include itaconic acid, maleic acid, fumaric acid, 2-carboxyethyl acrylate (b-CEA), and combinations thereof.

[0029] In other inventive embodiments, the adhesive is a polyurethane prepared by reaction of an organic polyisocyanate with an organic polymer containing isocyanate-reactive hydroxyl groups. Isocyanate reactive hydroxyl groups in some inventive embodiments are present in polyesters, polyethers and/or polyesteramides. The organic polyisocyanate in some inventive embodiments is aromatic, while in other inventive embodimients the polyisocyante is aliphatic and illustratively includes polymethylene diisocyanates such as ethylene diisocyanate and hexamethylene diisocyanate, or alkylene diisocyanates such as propylene- 1, 2-diisocyanate. The polyisocyanate, which may itself be a prepolymer containing recurring and/or terminal isocyanate groups, is generally prereacted in molar excess with the polyhydroxyl-containing reactant to yield a liquid prepolymer containing residual isocyanate groups. The prepolymer is subsequently cured, either through resort to a cross linking agent, such as diols or diamines such as 4,4'-methylene bis-(2-chloroaniline) (MOCA), or even water; or can be rendered heat and/or air drying air-curing/drying emulsion by adding a catalytic amount of an organometallic of metals such as cobalt, tin, zirconium, manganese, bismuth, or zinc bonded to organic groups such as naphthenate, or a peroxide such as methyl ethyl ketone peroxide from 0 to 2 percent by weight of the water insoluble dispersed phase of a urethane emulsion.

[0030] A urethane composition is rendered as an oil-in-water emulsions through resort to C8-C24 alkyl alcohols that facilitate ionic surfactant emulsification. As a result polyurethane precursor droplet sizes as small as 0.1 m are prepared with surfactant that form stable oil in water emulsions. Exemplary of the formation of urethane compositions is US20190309174A1.

[0031] The adhesive is devoid of polyester, polyurethane, and polyamide in amounts of greater than zero adhesive layer weight percent. The adhesive layer is also readily formed without resort to hot melt powders that are conventional to the art. While in other inventive embodiments, the adhesive contains less than 20 weight percent polyester, polyurethane, and polyamide or combinations thereof. In still other inventive embodiments, the adhesive contains between 5 and 20 weight percent polyester, polyurethane, and polyamide or combinations thereof. [0032] As used herein, “molecular weight” in regard to a polymer refers to weight average molecular weight (MW).

[0033] The alkyl acrylates and cycloacrylates operative herein include Ci-Cs alkyl acrylates regardless of whether linear or branched and Cs-Cs cycloacrylates. Specific alkyl acrylates and cycloalkyl acrylates operative herein include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, hexyl, 2-ethylhexyl, nonyl, dodecyl, octadecyl, cyclopentyl, cyclohexyl, phenyl, and isodecyl acrylates; and combinations thereof.

[0034] An ester of mono- or di- (Ci-Cs alkyl) a- or b-ethylenically unsaturated dicarboxylic acid operative herein illustratively includes mono- or di-alkyl ester of one or more of fumaric, maleic, or itaconic acids.

[0035] The acrylic polymer adhesives of the present invention used in layers 32 or 32’ are soluble in esters, alcohols, and alcoholic ether with the proviso that the solvent is liquid at standard temperature and pressure. Specific solvents operative herein include ethyl acetate, Ci-Cs alkyl alcohols, cellosolves, mixtures, and azeotropes thereof.

[0036] The polymerization of the monomers to form an inventive acrylic adhesive polymer include any conventional method of radical polymerization usually used for this type of monomer. The polymerization readily occurs in the monomer mass, in a solvent medium or in an emulsion, in the presence of a radical initiator. An exemplary process for which is detailed in FR2765878A1. The resulting polymer is slightly anionic and readily emulsified in water with addition of a protective colloidal thickener such as sodium polyacrylate. Emulsion pH values range from 7.5-9.5 at solids content of 10-55% by weight.

[0037] It is noted that in specific inventive embodiments, depending upon the DWR fabric or substrate, a simple adhesive ink made with the specialty acrylic polymer used in the DWR fabric will be suitable. However, in other cases it may be necessary to incorporate a hot melt adhesive powder to help improve the durability of the label 30 or 40 on the fabric. However, as previously noted, it is preferable to avoid the use of hot melt particles scattered throughout the adhesive. When melted to facilitate the heat transfer process the resultant “glue” is a hazy mixture of carrier resin and hot melt polymer. For printing reasons the adhesive is printed larger than the graphic resulting in a glue line halo around the image. This glue line halo is objectionable from an aesthetic point of view and in some cases label manufacturers have resorted to laser cutting the heat transfer label to eliminate the glue line halo. This is an added step in the manufacturing process and adds cost to the label.

[0038] A hot melt adhesive may be present from 0 to 20 total weight percent of an inventive adhesive. A hot melt adhesive operative herein illustratively includes thermoplastic polyurethanes (TPUs), copolyamides (CoPA), and copolyesters (CoPES) such as those commercially available as Unex powders from Fixatti, Griltex powders from EMS-Griltech, and Rowalit powders from Rowak AG.

[0039] A rheological modifier is present from 0 to 4 total weight percent of an inventive adhesive. A rheological modifier operative herein illustratively includes polyether urea polyurethanes; reaction products of poly alky lene oxides with polyfunctional polyols, amines, amine alcohols, thiols and polyisocyanates, as detailed in U.S. Patent No. 4,337,184; organoclays; and combinations thereof.

[0040] A defoamer is present from 0 to 5 total weight percent of an inventive adhesive. A defoamer operative herein illustratively includes mineral oil carrier, hydrophobic silica, ethylene bis-stearamide, acrylic polymers, propoxylate polymers, silicone oil, and combinations thereof.

[0041] A matting agent is present from 0 to 4% total weight percent of an inventive adhesive and functions to diffract light to reduce the gloss associated with the adhesive layer. A matting agent operative herein illustratively includes fumed silica, wax powder, and combinations thereof. [0042] Table 1 shows adhesive formulations according to the present invention with material amounts as weight percentages to the adhesive formulation unless stated otherwise. Table 1: Adhesive Formulations for heat transfer labels with amounts provided as total weight percentages of the adhesive formulation:

[0043] In specific inventive embodiments where improved adhesion of the transfer label is required, an alternative to the use of hot melt particles to increase adhesion may be achieved with the inclusion of a latent cross-linking agent in the ink as described in Yang et al. (U.S. Patent No. 8,507,616). With the inclusion of a blocked cross-linking agent, such as a blocked isocyanate, depending upon the blocking agent the temperature range over which the isocyanate unblocks and can become reactive can be controlled. For example, as shown in Table 2, blocking agents are unblocked in specific temperature ranges.

Table 2: Unblocking temperature ranges for blocking agents:

[0044] Selection of the proper blocking agent allows for the protection of the blocked isocyanates up until a certain temperature range. For example, selecting 3,5-dimethylpyrazole allows for printing and drying an ink at temperatures up to about 100°C without activating the isocyanate. When the label is applied to the fabric at temperatures of from 135-150°C, the isocyanate unblocks and begins to react with molecules that have an active hydrogen, such as amines, alcohols, and acids. If the substrate fabric has any of these functional groups and the ink has any of these functional groups, a graft reaction may occur that binds the ink to the substrate. In the absence of functional groups in the fabric but still having the presence of functional groups in the ink, a cross-linking reaction of the ink with itself may occur. This results in some inventive embodiments in a stronger and less reversible chain entanglement of the ink with the fabric resulting in a more permanent bond. As mentioned in Yang et a , it is also advantageous to have a catalyst to speed up the grafting/cross-linking reactions so they occur during the short duration of the application step (i.e., 10-15 seconds). In specific inventive embodiments, resins such as hydroxy functionalized polyurethanes as well as carboxylic acid containing acrylic emulsions may be incorporated in the adhesive formulation to promote cross-linking.

[0045] The hydroxy functionalized polyurethane is obtainable by chemical crosslinking of a polyurethane prepolymer obtained by chemical reaction of: one or more aliphatic polyester polyols having a hydroxy functionality of from 1.8 to 33 inclusive and a number average molecular weight equal to or greater than 1000 g/mol with one or more compounds having a hydroxy functionality of 1.8 to 33 inclusive and a number average molecular weight of less than 1000 g/mol mol, and one or more aliphatic diisocyanates, with the ratio of the total number of isocyanate groups to the total number of hydroxyl groups of the substances involved in the chemical reaction for the construction of the polyurethane prepolymer is greater than or equal to 0.4 and less than 1. Number average molecular weights of the resulting hydroxy functionalized polyurethane range between 600 and 4500. Exemplary hydroxy functionalized polyurethanes operative herein are also detailed in JP2006182795 A. [0046] Carboxylic acid containing acrylic emulsions are also operative herein and are detailed in U.S. Patent No. 6,887,933 and U.S. Patent No. 8,507,616. In some inventive embodiments, the acrylic contains a thermoplastic acrylic resin that is a hydrophobic polymer to impart water resistance to the resulting construct. In still other inventive embodiments, the glass transition temperature of the thermoplastic acrylic resin is between 45 and 90 ° Celsius. In other inventive embodiments, the solubility parameter is between 7 and 12.

[0047] As further noted in Yang et al. (U.S. Patent No. 8,507,616) with the incorporation of adhesive like qualities into a pigmented ink a separate adhesive layer may not be needed for application of the transfer label. The result would be a simpler label constmction.

[0048] The present invention is further described with respect to the following non limiting examples. These examples are intended to illustrate specific formulations according to the present invention and should not be construed as a limitation as to the scope of the present invention.

EXAMPLES

Example 1-3

[0049] Adhesive formulations are provided as follows in Table 3 with material amounts as weight percentages to the adhesive formulation unless stated otherwise.

[0050] Table 3: Adhesive Formulations for heat transfer labels with amounts provided as total weight percentages of the adhesive formulation. It is appreciated that such formulations are dispersed in water.

Example 4

[0051] Test labels are produced by screen printing onto a 4-mil thick release coated polyester film. The test labels are a simple one-color white graphic printed with a suitable white polyurethane water based printing ink. Two passes of white are printed followed by two passes of adhesive. The adhesives of Examples 1-3 tested in this manner. Examples 1 and 3 yield a more transparent adhesive halo around the graphic image due to the absence of the matting agent.

[0052] The test labels are applied with an Insta stamping machine with the following parameters; die face temperature setting 150°C, pressure 4 bar, and dwell 15 seconds. Both labels applied in such a manner passed a standard 5 cycle wash test at 60°C.

Example 5

[0053] Labels with adhesive formulations as described in Examples 1-3 are applied to non-DWR treated fabrics including synthetic fabrics illustratively including polyester and nylon, as well as natural fabrics such as those formed of cotton. The test labels were applied with an Insta stamping machine with the following parameters; die face temperature setting 150°C, pressure 4 bar, and dwell 15 seconds. Both labels applied in such a manner passed a standard 5 cycle wash test at 60°C with a standard drying cycle following each wash.

[0054] The results indicate that the acrylic emulsion based adhesive acts as a universal adhesive, which is a surprising result in that typically a different adhesive might be required for each fabric type and most definitely a different adhesive for synthetics like polyester and nylon vs. natural such as cotton.

Example 6

[0055] The composition of Example 1 is used except that a like amount of polyurethane adhesive replaces the acrylic adhesive. As a comparative a prior art label per the background of the invention is formed with like amounts of polyurethane. The label is applied to DWR treated polyester and nylon. The test labels were applied with an Insta stamping machine with the following parameters; die face temperature setting 150°C, pressure 4 bar, and dwell 15 seconds. Inventive and comparative labels adhered well, but after a standard 5 cycle wash test at 60°C with a standard drying cycle following each wash, all the inventive labels adhered while every comparative label had a degree of delamination.

[0056] Patent documents and publications mentioned in the specification are indicative of the levels of those skilled in the art to which the invention pertains. These documents and publications are incorporated herein by reference to the same extent as if each individual document or publication was specifically and individually incorporated herein by reference. [0057] The foregoing description is illustrative of particular embodiments of the invention but is not meant to be a limitation upon the practice thereof. The following claims, including all equivalents thereof, are intended to define the scope of the invention.

Claims

1. A heat transfer label to be applied to a durable water repellent (DWR) substrate comprising: a carrier web; one or more ink layers that define a graphic supported on the carrier web; and at least one adhesive layer adapted to bond to the DWR substrate and comprising an acrylic composition or polyurethane composition that is devoid of both polyester and polyamide.

2. The label of claim 1 further comprising a release coat applied to the carrier web and intermediate between the carrier web and the one or more ink layers.

3. The label of claim 1 further comprising a backup layer formed of a white ink intermediate between the one or more ink layers and the at least one adhesive layer.

4. The label of claim 1 further comprising a dye migration barrier layer intermediate between the one or more ink layers and the at least one adhesive layer and if the backup layer is present, in contact with the backup layer.

5. The label of claim 1 further comprising at least one of a rheology modifier, a defoamer, or a matting agent.

6. The label of claim 1 further comprising a hot melt adhesive powder.

7. The label of any one of claims 1 to 6 wherein the carrier web is formed of polyester, polylactic acid, poly(lactic-co-glycolic acid), polycaprolactone, poly a-hydroxy esters, and laminates containing any of the aforementioned

8. The label of any one of claims 1 to 6 wherein the carrier layer has a thickness of 5 to 500 pmeters.

9. The label of any one of claims 1 to 6 wherein the graphic is a single pass of one color or several passes of the same color or of different colors.

10. The label of any one of claims 1 to 6 wherein the acrylic composition has a molecular weight of between 2000 and 100,000.

11. The label of any one of claims 1 to 6 wherein the substrate is a fabric.

12. The label of claim 1 wherein the acrylic composition is obtained by the polymerization of: 65 to 95% by weight of alkyl acrylates, cycloalkyl acrylates, arylacrylates, or a combination thereof; 0 to 20% by weight of acrylic acid; and a remainder by weight of at least one ester of mono- or di- (C1-C8 alkyl) a- or b-ethylenically unsaturated dicarboxylic acid.

13. The label of claim 12 wherein the alkyl acrylates or the cycloacrylates are at least one of Ci-Cs alkyl acrylates or C -C_K cycloacrylates.

14. The label of claim 12 wherein the ester of mono- or di- (Ci-Cs alkyl) a- or b- ethylenically unsaturated dicarboxylic acid is a mono- or di-alkyl ester of one or more of fumaric, maleic, or itaconic acids.

15. The label of claim 1 wherein the acrylic composition is a copolymer of styrene and an acrylic ester monomer, the acrylic ester monomer having a C1-C3 alkyl group atoms or being a C6-C12 aromatic acrylic ester.

16. The label of claim 15 wherein the amount of the acrylic ester monomer is from 30 to 85 weight percent of the copolymer.

17. The label of claim 1 wherein the acrylic composition is present as an oil in water emulsion.

18. The label of claim 17 wherein the oil in water emulsion has a pH of 8 to 9 at 10% solids in an aqueous solution at 20°C.

19. A heat transfer label to be applied to a durable water repellent (DWR) substrate comprising: a carrier web; one or more ink layers that define a graphic supported on the carrier web, the one or more ink layers further comprising inclusion of a latent cross-linking agent in the ink; and wherein the one or more ink layers adapted to bond to the DWR substrate.

20. The label of claim 19 wherein said latent cross-linking agent comprises a blocked isocyanate.

21. The label of claim 19 or 20 further comprising a catalyst for the latent cross-linking agent, the catalyst being an organo-metallic catalyst, wherein the metal ion is one or more of cobalt, tin, zircomium, manganese, bismuth, and zinc.

22. A method for imparting a label to a substrate comprising: positioning the heat transfer label of claim 1 on the substrate; applying heat and pressure to the label from a backside of the carrier web to bond the graphic to the substrate; and removing the carrier web to expose the graphic on the substrate.

23. The method of claim 22 wherein conditions of the applying the heat and pressure are temperatures of between 80 and 200°C, pressures of from 01 to 20 bar, and contact times of from 1 to 120 seconds.

24. An adhesive formulation comprising: an acrylic composition with a molecular weight of between 2000 and 100,000, the acrylic composition is obtained by the polymerization of: 65 to 95% by weight of alkyl acrylates, cycloalkyl acrylates, arylacrylates, or a combination thereof; 0 to 20% by weight of acrylic acid; and a remainder by weight of at least one ester of mono- or di- (C1-C8 alkyl) a- or b-ethylenically unsaturated dicarboxylic acid, the acrylic composition present as an oil in water emulsion and forming a majority by weight of the formulation; an additive of a rheology modifier, a defoamer, a matting agent, or a combination thereof, the additive or the combination of additives forming a minority by weight of the formulation; and devoid of a hot melt particles.

25. The formulation of claim 24 being devoid of polyester, polyurethane, and polyamide.

26. The formulation of claim 25 further comprising a hot melt adhesive.

27. An adhesive formulation comprising: a urethane composition with a molecular weight of between 2000 and 100,000, present as an oil in water emulsion and forming a majority by weight of the formulation; an additive of a rheology modifier, a defoamer, a matting agent, or a combination thereof, the additive or the combination of additives forming a minority by weight of the formulation; and devoid of a hot melt particles.

28. The formulation of claim 27 being devoid of polyester and polyamide.

29. The formulation of claim 27 further comprising a hot melt adhesive.