MXPA97006041A - Compositions and donor elements of thermal mass transfer to be used in the production of signalarticulars - Google Patents

Abstract

Coated, thermal mass transfer precursor compositions suitable for producing thermal mass transfer donor elements are disclosed, the compositions that can be coated include a polyalkylene binder precursor, an acrylic binder precursor, an effective amount of a pigment to provide the desired color to a thermal mass transfer composition using the recoverable composition, and d) a diluent (preferably water) in which the polyalkylene binder precursor, acrylic binder precursor and pigment, is they all find scattered there. Signage items produced using the donor elements are also described

Description

COMPOSITIONS AND DONOR ELEMENTS OF TRANSFER OF THERMAL MASSES FOR USE IN THE PRODUCTION OF SIGNALING ITEMS.

BACKGROUND OF THE INVENTION 1. Field of the invention The present invention relates to thermal mass transfer compositions and articles for use in the production of signaling articles. In particular, the present invention relates to the use of thermal mass transfer compositions that employ a binder that does not significantly absorb ultraviolet radiation, thus preventing substantial absorption of heat and degradation of the binder, and including stable, durable pigments that do not present a significant color change or loss of brightness. 2 . Related technique Thermal mass transfer procedures use a donor or donor layer (commonly referred to as "ribbon" or "sheet") and a receiving sheet or substrate.

Ref: 25281 The thermal mass transfer donor sheet normally comprises a carrier layer and a coloring layer with at least one thermally transferable colorant (a colorant or preferably a pigment) in a binder that can be softened by heat. The coloring layer is typically composed of a pigment dispersed in a binder (the binder being transferred with the pigment during thermal transfer). The thermal mass transfer sheets are used with the surface of the donor (coloring layer) in intimate contact with a receiving material, and the donor sheet is heated in an image-like manner (eg by thermal print heads, irradiation as by a laser or high intensity radiation transmitted through a mask or stencil) to transfer the image forming material. In the thermal mass transfer system, the coloring layer is softened by image heating (and sometimes a receptor layer on the receiving sheet is softened contemporaneously) and the smoothed area is transferred to the receiving sheet. The final use of the substrate that has the image transferred on it frequently dictates the durability requirements of the image.

Thermal mass transfer is useful for printing durable outdoor signage items, such as automobile registration labels that are affixed to patent plates. See, for example, Patent Cooperation Treaty, applications WO 94/19710 (claiming United States Priority Nos. 08 / 017,573 and 08 / 033,627) and WO 94/19769 (claiming United States Priority Nos. series 08/017573 and 08 / 033,625), both published on September 1, 1994. For the articles described here, the signs transferred by thermal mass were printed on a "multifunction" layer of specially formulated polyurethane, an attribute of which speaks eliminate the need for a coating layer for printed signs with resin-based binder. Many commonly used binders employ large amounts of UV stabilizers and UV absorbers, which tend to produce heat in the binders and cause their early degradation, thus decreasing the gloss and / or increasing the color change. There is a need in the signaling art, particularly those for outdoor use, to be able to apply color images to many different substrates without loss of brightness or color change and without having to use complex procedures.

BRIEF DESCRIPTION OF THE INVENTION The present invention solves many shortcomings of the prior art with regard to the provision of long-lasting, good quality thermal mass transfer images (ie minimal color change and minimal loss of brightness). The durability of the thermal mass transfer images produced by the methods of the invention is improved by the use of thermal mass transfer precursor compositions including dispersions of organic and / or inorganic pigments. How it is used here, the term "thermal mass transfer precursor composition" means a film-forming composition (preferably aqueous), which can be coated, comprising binder precursors and pigments. Binder precursors are present in the compositions that can be coated, while the term binder means the solid residues of the binder precursors. The term thermal mass transfer composition means a solid composition present either in a donor element of the invention or as an image in a substrate. According to one aspect of the present invention, recoverable, film-forming, thermal mass precursor compositions are disclosed, comprising: a) a polyalkylene latex binder precursor, b) a binder precursor acrylic latex, c) an effective amount of a pigment to provide the desired color to a thermal mass transfer composition using the composition, and d) a diluent (preferably water) in which the polyalkylene latex binder precursor, precursor to acrylic latex binder and pigment are all dispersed, wherein the pigment and the acrylic binder precursor are present in a weight ratio of pigment to acrylic binder precursor ranging from ca. 0.5. 1.0 to approx. 1.5: 1.0, and the acrylic latex binder precursor is present in an amount to provide the low transparent to visible and UV light desired to the thermal mass transfer composition. It will be understood that optional ingredients such as emulsifiers, dispersion aids, surfactants and the like, will normally be included in commercial embodiments of the film-forming compositions, which can be coated, as further described herein, while the transfer composition of resulting thermal mass (other than pigments, dyes or colorants) is substantially transparent to UV. The term polyalkylene not only includes polyethylene, polypropylene, polybutadiene and the like, but also polyalkylene type oligomers and polymers, which have a high percentage of methylene units, such as oligomeric compositions comprising the reaction product of a low molecular weight organic acid, such as acrylic acid, and a high molecular weight alcohol or short chain diol. As used herein, the term "acrylic" includes copolymers and terpolymers of an alkylene monomer and an acidic copolymerizable monomer. Examples of alkylene monomers include ethylene, propylene, and the like, and examples of acidic copolymerizable monomers include acrylic acid and alkylacrylic acids such as methacrylic acid, ethacrylic acid, and the like.

The term that can be coated means that the compositions of the invention have a viscosity of no more than 50 centipoise, measured using a Brookfield viscometer, spindle # 2, at room temperature (about 20 ° C). Another aspect of the invention is a thermal mass transfer donor element comprising a dried version of the composition of the invention (i.e. a thermal mass transfer composition) adhered to a vehicle, wherein the vehicle is preferably a film, more preferably a polymeric film. The compositions and donor elements of the invention can be used in conventional processes to provide a thermal mass transfer image on a substrate. Thus, another aspect of the invention is a signaling article comprising a thermal mass transfer composition of the invention adhered to a substrate, thereby forming a coloring layer. The heat transfer methods used to produce these articles typically comprise the steps of placing the dye layer of a thermal mass transfer donor element in contact with a second surface, and transferring at least a portion of the transfer composition. of thermal mass of the donor element to the second surface by heating at least a portion of the thermal mass transfer donor layer. Preferred substrates are paper, metal and polymers, with polymeric substrates being particularly preferred, for example the polymer surface of a retroreflective coating. Particularly preferred signage items include durable outdoor signage, such as highway signs, self-adhesive labels for validation of automobile registration and self-adhesive for windows and license plates. The coloring layer of the signaling articles of the invention can be exposed or covered by one or more polymeric layers (particularly polymethylmethacrylate (PMMA)) or glass coating, but for uses for which prolonged exposure to weather is expected. A coating layer is particularly desired. The thickness of the coloring layer in articles of the invention is preferably from approx. 1 to approx. 10 micrometers, more preferably from approx. 2 to approx. 8 micrometers, and more preferably still from approx. 3 to approx. 6 micrometers. The coloring layer (in the thermal mass transfer donor elements and the signaling articles of the invention) has a softening or melting temperature between 50 ° C and 140 ° C, preferably from approx. 60 ° C and 120 ° C, more preferably from 65 ° C and 110 ° C and more preferably still from 70 ° C and 100 ° C. In donor elements of the invention that employ a polymeric film vehicle (preferably polyethylene terephthalate (PET)), the polymer film preferably has a thickness ranging from ca. 1 and approx. 10 micrometers, more preferably from approx. 2 to approx. 6 micrometers. For formulating the film-forming compositions, which can be coated, of the invention, it is important, particularly if transparent colors are desired in the signaling articles of the invention, to avoid agglomeration of the pigment particles. Thus, another aspect of the invention is a method for formulating a film-forming composition, which can be coated, the use of the composition being suitable for producing a thermal mass transfer-giving element, the method comprising the steps of: a) add water to an amount of a pigment dispersion using moderate agitation to form a first intermediate, b) add methanol to the first intermediate to form a second intermediate, c) add an acrylic dispersion to the second intermediate to form a third intermediate, and d) add a polyalkylene emulsion to the third intermediate to form the composition that can be coated, wherein the amount of water and methanol is sufficient to give the composition a weight percentage of solids ranging from ca. 1 to approx. 20 weight percent, and the pigment dispersion, the acrylic latex, and the polyalkylene emulsion are present in a weight ratio of approx. 1: 1: 4 The invention will be more fully understood with reference to the following detailed description of the invention.

Brief description of the drawing Fig. 1 is a sectional view (enlarged) of an illustrative thermal mass transfer donor element according to the present invention, Fig. 2 is a sectional view (enlarged) of an illustrative retroreflective signaling article in accordance with the present invention, Fig. 3 is a sectional view (enlarged) of an illustrative paper signaling article in accordance with the present invention.

The figures are not in scale and are merely illustrative of the invention.

Description of preferred embodiments I. Thermal mass transfer precursors, film formers, which can be coated The binder or binder precursors of thermal masses useful in the invention function (in the binder form) primarily to provide the necessary adhesion of the thermal mass transfer composition to the substrate. The acrylic latex binder precursors also provide binders that retain their optical properties for extended periods of time of exposure to outdoor conditions, especially when protected from abrasion via a plastic or glass cover layer. The tests for color change and gloss retention are included in the Test Methods Section. The acrylic latex binder precursors, after drying and film formation, also provide a high degree of water resistance for all substrates and corrosion resistance for metal substrates. The acrylic latex binder precursors, thermoplastics are available as aqueous dispersions, typically and preferably having a solids percent ranging from about 10 to about 80 weight percent, a pH ranging from about 6.0 to 8.0 and an Acidity Index ranging from about 30 to about 80, more preferably from about 60 to 80, a viscosity ranging from about 5 to about 500 centipoise measured at 25 ° C using a Brookfield viscometer, spindle No. 2, and a glass transition temperature varying between ca. 20 and 70 ° C, more preferably between approx. 25 and approx. 60 ° C. Preferred aqueous acrylic film-forming dispersions are those known under the trade names CARBOSET XL-11 and CARBOSET 514H, from BFGoodrich, Cleveland, Ohio, where the XL-11 version is 30 weight percent solids and has a viscosity of 50 centipoise, a pH of 6.7, an acid number of 75, and glass transition temperature of 55 ° C and version 514H, which has 40% by weight solids, a viscosity of 350 centipoise, a pH of 7 , 0, an acid number of 65, and glass transition temperature of 28 ° C. The polyalkylene binder precursor has the function (in the form of a binder) of a wax component. The thermally transferred compositions of the invention preferably comprise at least one polyalkylene binder, typically and preferably derived from an aqueous film-forming dispersion comprising 0.01 to 5 microns of particulate solid (preferably optically clear). Preferred polyalkylene binder precursors are micron-sized particulate solids, and can include any solid, fine, transparent polyalkylene particle, which is not soluble and yet easily dispersible to form the thermal mass transfer precursor compositions. filmmakers, which can be coated, of the invention. Polyethylene polymers having low differentials in their refractive indices of acrylic binders are preferred. The differential low is preferred for the comparison of the Refractory Index to reduce the light scattering in the coloring layer.

Since the precursors of acrylic latex and polyalkylene latex binders are immiscible, the minor component of the two (the acrylic binder) forms islands in the film formed by the main component (the polyalkylene binder). Therefore, the ratio of these two ingredients has to be carefully optimized in the film-forming compositions, which can be coated, of the invention, to provide adequate cohesiveness of the thermal mass transfer composition, dried, for the taking of high resolution images. As both the acrylic and the polyalkylene binder are thermoplastic, both contribute to the necessary adhesion to the receiver during thermal mass transfer printing. The polyalkylene binder also functions as a wax type material as it helps to make the transferred image conform to the rough surface, such as paper, or around and between the glass beads in the retroreflective encapsulated lens coating. The polyalkylene material and optional particulate solids also provide the benefits of reducing the input of energy in the printhead during the thermal mass transfer process.The polyalkylene binder precursors can be obtained as dispersions and emulsions having viscosities ranging from ca. 10 and approx. 70 centipoise, oscillating the pH between approx. 7 and 10, oscillating the percent solids between approx. 10 and approx. 80 percent by weight, and they are typically and preferably clear and transparent. An exemplary polyalkylene latex binder precursor is the one known under the trade designation POLY EMULSION 330 N35, which is available from Chemical Corporation of America, East Rutherford, NJ, which is a 35 weight percent emulsion of latex solids. of film-forming polyethylene known under the trade name AC-330 from Allied Chemical Corporation. The emulsion has a non-ionic charge, a viscosity of 50 centipoise maximum, a pH ranging from ca. 8.5 and approx. 9.5 and it is clear and transparent. To further reduce the cohesion of the coloring layer, non-thermoplastic, non-film-forming solid particles can be employed. Preferred acrylic, non-film-forming particulates are a dispersion of 10 percent solids in deionized water of stearylmethacrylate hexanedioldiacrylate polymers, preferably present in a weight ratio of 1: 1. Other optional non-film-forming solid particulates may be preferred for adapting higher resolution and lower energy for imaging (i.e., the energy required to transfer the composition from the PET or other donor to the intended recipient). These include but are not limited to Ti02, MgO, ZnO, CaCO3, SiO2, micas and the like. The film-forming compositions, which can be coated, of the invention preferably comprise a weight ratio of from approx. 0.5: 1.0 to approx. 1.5: 1.0 between pigment dispersion and dispersion of acrylic latex binder precursor, and a weight ratio between pigment dispersion and dispersion of polyalkylene latex binder precursor ranging from ca. 0.1: 1.0 and 0.33: 1.0. In the thermal mass transfer compositions of the invention (solid) the weight ratio between pigment and acrylic binder ranges from ca. 0.5: 1.0 and approx, 1.5: 1.0, while the weight ratio between the pigment and the polyalkylene binder ranges from ca. 0.1: 1.0 and approx. 0.33: 1.0.

Preferably, the thermal mass transfer compositions of the invention have a melting point (mp) or softening point (pa) ranging from ca. 50 ° and approx. 140 ° C to increase the thermal mass transfer efficiency. Melting points below 50 ° C indicate a composition that can become sticky and blocking when not intended, while melting points above 140 ° C could possibly degrade the vehicle during coating and kiln drying and certainly they would increase the thermal energy requirement to transfer the composition to the intended substrate.

B. Pigments The pigments useful in the invention may be organic or inorganic. Suitable inorganic pigments include carbon black and titania (TiO?), While suitable organic pigments include phthalocyanines, anthraquinones, perylenes, carbazoles, monoazo- and diazobenzimidazolone, isoindole inones, monoazonaphthol, diarylpyridolzolone, rhodamine, indigoid, quinacridone, diazopirantrone, dinitraniline, pyrazolone, dianisidine, pyrantrone, tetrachloroisoindole inone, dioxazine, monoazoacrilide, anthrapyrimidine. Those skilled in the art will recognize that the organic pigments may have different shades, or even different colors, depending on the functional groups attached to the parent molecule. However, many of the aforementioned organic pigments exhibited good weather resistance in simulated external use as they retain much of their initial brightness and color, as exemplified here below. Commercial examples of useful organic pigments include those known under the trade names PB 1, PB 15, PB 15: 1, PB : 2, PB 15: 3, PB 15: 4, PB 15: 6, PB 16, PB 24 and PB 60 (blue pigments); PB 5, PB 23, and PB 25 (brown pigments), PY 3, PY 14, PY 16, PY 17, PY 24, PY 65, PY 73, PY 74, PY 83, PY 95, PY 97, PY 108, PY 109, PY 110, PY 113, PY 128, PY 129, PY 138, PY 139, PY 150, PY 154, PY 156, and PY 175 (yellow pigments); PG 1, PG 7, PG 10 and PG 36 (green pigments); PO 5, PO 15, PO 16, PO 31, PO 34, PO 36, PO 43, PO 48, PO 51, PO 60 and PO 61 (orange pigments); PR 4, PR 5, PR 7, PR 9, PR 22, PR 23, PR 48, PR 48: 2, PR 49, PR 112, PR 122, PR 123, PR 149, PR 166, PR 168, PR 170, PR 177, PR 179, PR 190, PR 202, PR 206, PR 207 and PR 224 (red); PV 19, PV 23, PV 37, PV 32 and PV 42 (violet pigments), and PBLACK (black), several of which can be obtained from Heucotech, Fairless Hills, PA as aqueous dispersions under the trade name AQUIS II. Other commercially available useful aqueous dispersions include those known under the trade designations AQUALOR (available from Penn Color Inc., Doylestown, PA, MICORLITH-WA) (obtainable from CIBA-GEIGY Corporation, Oak Division pigments). Brook, IL), SUNSPERSE, FLEXIVERSE and AQUATONE) (obtainable from Sun Chemical Corporation, Dispersions Division, Amelia, OH, and HEUCOSPERSE III) (available from Heucotech Ltd. Fairless Hills, PA).

II. Thermal Mass Transfer Giver Elements The constructions of the thermal transfer donor elements of the present invention comprise a thermal mass transferable dye layer comprising a dried version of a recoverable composition, of the invention, coated on a vehicle. Fig. 1 illustrates a donor element 100 such as this, having a dye layer 12 coated on a vehicle 14, in this embodiment a thin polyethylene terephthalate (PET) film (4.5 micrometers thick). An optional release / anti-peel coating 16 is also illustrated. The carrier or carrier materials suitable for the thermal mass transfer donor element can be any flexible material to which a transparent dried coloring composition or an opaque metallic / white pigment layer can adhere. Suitable vehicles can be liquid or rough, transparent or opaque, and continuous (or sheet type). They are preferably essentially non-porous. Non-limiting examples of materials that are suitable for use as a vehicle include polyesters, especially PET, polyethylene naphthalate, polysulfones, polystyrenes, polycarbonates, polyimides, polyamides, cellulose esters, such as cellulose acetate and cellulose bitirate, chlorides of polyvinyl and derivatives, and the like. The substrate generally has a thickness of 1 to 500 micrometers, preferably 2 to 100 micrometers, more preferably 3 to 10 micrometers. Particularly preferred vehicles are PET filled with white or transparent or opaque paper. By "non-porous" in the description of the invention it is meant that ink, paints or other means of coloring liquids or anti-stick compositions will not flow rapidly through the vehicle (eg, less than 0.05 per second vacuum applied). 7 torr, preferably less than 0.02 mi per second at vacuum applied to 7 torr). In a preferred embodiment a release / anti-stick coating is applied to the back of the donor element (i.e., the side opposite the thermally transferable dye layer) to improve the handling characteristics of the donor element, reduce friction and avoid that the donor element sticks to the printing substrate. Suitable release / anti-stick materials include, but are not limited to, silicone materials including poly (lower alkyl) siloxanes such as polydimethylsiloxane and silicone-urea copolymers and perfluorinated compounds such as perfluoropolyethers. The thermal mass transfer donor or donor elements of the invention are suitable for the production of images in desktop advertising, direct non-critical digital color testing, manufacture of signs in small and large lots, etc. especially when the graphic image is intended to be weather resistant and durable.

As used herein, the terms "durable" and "durability" refer to characteristics such as resistance to solvents and chemicals, resistance to abrasion, maintenance of the binding of the thermal mass transfer composition to the substrate, and maintenance of the brightness of the color and ( for retroreflective substrates) of the retroreflective sheen. The terms weather-resistant and weather-resistant refer to characteristics such as retroreflective, dirt-resistant maintenance, resistance to yellowing and the like, all under normal weather conditions, where light of the sun, temperature and other environmental parameters can affect performance. In the formulation of the recoverable film-forming compositions of the invention, it is important that the pigment particles remain non-agglomerated to produce transparent color images. One method, detailed in the examples, uses a ball mill. A more preferred method is to formulate the film-forming compositions, which can be coated, of the invention in the following manner. To formulate a 10 percent solids composition (in a diluent composed of a 1: 1 weight ratio of deionized water / methanol) of a 1: 1.4 weight ratio composition of (1) the known pigment dispersion under the trade name PB 15: 3; (2) the acrylic latex known under the trade name CARBOSET 514H; and (3) the polyethylene emulsion known under the trade name POLYEMULSION AC 330 N35, is first added by spreading the pigment under moderate mixing conditions to a flask, followed by the addition of deionized water. With continuous moderate agitation, methanol is introduced, followed by the acrylic dispersion and then the polyethylene emulsion. If the proper order of addition is followed, a "startle" or agglomeration of the pigment does not occur, so that ball milling is unnecessary. Changing the solvents from ethanol to methanol prevents less viscosity from forming in the composition (ethanol causes the polymers to increase in volume, making it difficult to coat the composition on the desired vehicle). The coating of the recoverable film-forming thermal mass precursor compositions of the invention on the vehicle can be performed by many standard coil coating techniques such as gravure printing, extrusion coating on single or double slot and similar. Gravure printing is particularly useful for patch-type coatings where there are interspersed regions of opaque metallic or white dyes on a ribbon or layer.

III. Signaling items The donor elements of the present invention are generally used in the thermal mass transfer printing by contacting the transferable dye layer of the tape donor element of the invention with a receiving sheet or film (i.e., a substrate) such that the dye layer Thermally transferable dye is in contact with the receiving sheet. Heat is applied, either from a thermal needle or an infrared heat source such as an infrared laser or a heat lamp and the donor layer is transferred to the receiver. The heat can be applied to the back of the donor tape or the receiving layer or can be directly introduced to a transferable donor layer. Particularly preferred substrates are retroreflective coatings, such as those known under the trade name SCOTCHLITE, particularly the 3700, 4200 and 5300 series (all include retroreflective type lenses). Retroreflective coatings of incorporated lenses are disclosed in U.S. Patent No. 2,407,680, incorporated herein by reference. Also useful retroreflective substrates are the encapsulated lens coatings disclosed in US Patent Nos. 3,190,178.; 4,025,159; 4,896,943; 5,064,272; and 5,066,098, all incorporated herein by reference and cube corner retroreflective laminate, such as those described in U.S. Patent Nos. 3,648,348; 4,801,193; 4,895,428; and 4,938,563, all incorporated herein by reference. Fig. 2 illustrates in an enlarged cross-section an embodiment or embodiment 200 of retroreflective signaling article, illustrative, according to the invention, comprising the thermal mass transfer composition in the form of desired, alpha-numeric indicia, bar codes, logos and the like, a layer 24 of polyvinyl butyral in which a plurality of transparent glass microspheres 26 are fitted. The layer 24 may also comprise other organic layers, such as gliptal, alkyde, copolymers of ethylene and / or propylene acrylic acid, ethylene methacrylic acid copolymer, ionomers, crosslinked and / or non-crosslinked aliphatic polyurethanes, vinyl, PMMA, and similar. A cover material 31 is illustrated on the printed indicia for abrasion resistance, chemical deterioration resistance, and the like, which would be desirable by users of the inventive articles in prolonged outdoor use (ie, more than 1 year) , such as license plates, road signs, street signs and the like. A reflective layer 28, a layer 30 of pressure sensitive adhesive, and a removable liner 32 complete the structure. Fig. 3 illustrates in enlarged section another embodiment 300 of the illustrative signage article according to the invention, comprising a thermal mass transfer composition 22 in the form of desired alphanumeric signs, bar codes, logos and the like, adhered to a flexible, non-retroreflective substrate 34. Suitable non-retroreflective substrates include vinyl film, paper with an ethylene / acrylic acid copolymer coating and PET coated with thermoplastic resin for use in. transparency with mirror.

The following test methods and examples further illustrate the present invention but should not be considered limiting.

TEST METHODS Accelerated weather meter test To simulate the conditions of exposure to the real external world to evaluate the retention of brightness and color change of the retroreflective coating printed by thermal mass transfer made in accordance with the invention, the test articles were inserted in an accelerated meteorological meter which employed a xenon arc light source cooled with water. The weather meter was a 65XWWR or Cl 65 model, obtainable from Atlas Electric Devices Co., and the procedures of ASTM G-26 Type B, BH, test designation 3-1 were followed. The weather meter used a test cycle consisting of alternating periods of 102 minutes of light at 63 ° C black panel temperature, then 18 minutes of light plus water spray. A 6500 watt xenon lamp was used, with an irradiance of 0.35 W / m2 at 340 nanometers of wavelength, which provides a good laboratory simulation of the Earth's sunlight.

Initial brightness and brightness retention The brightness of the articles was measured at the beginning and at the end of the exposure periods (500 and 1000 hours) with a retroluminometer as described in the U.S. Defensive Publication T987.003 at an observation angle of 0.2 ° and an entry angle of -4.0 °.

Color retention Color combination test scan L * a * b * Since color is the first stimulus the consumer perceives, resulting in an immediate evaluation of print quality, color consistency is one of the main quality attributes of the printed substance by thermal mass transfer. To determine the color change of the thermal mass transfer compositions of the invention after a certain time duration in the accelerated meteorological meter, a spectrophotometer known under the trade name SPECTROPLUS CAT, which can be obtained from Color and Appearance, was used. Technology Co., Princeton, NJ The spectrophotometer is designed to measure the reflectance color of objects. The measurement geometry of the meter spectrofot used was 0 ° / 45 °. This geometry provided the visualization of the samples similar to the normal visual evaluation, with 0 ° of illumination, or perpendicular illumination of the sample, in visualization of the sample at 45 °, the circumferential visualization of 45 ° effectively excludes the specular reflectance (glossy ). This geometry essentially eliminated the. effect of the directionality of the sample or printing texture. The spectrophotometer used operates essentially as follows. Light from a halogen lamp passes through a series of filters and lenses to simulate D65 daylight and remove heat and is focused on the sample in a circular pattern. (The print color was read in "Illuminant D65", which represents daylight with a correlated color temperature of about 6500 ° Kelvin). The diffusely reflected light from the sample is collected at 45 ° from the sample by a series of independent photodetectors stationed at various points around the sample, each photodetector detecting a different wavelength band. The information of each photodetector is then entered into a personal computer through an analog-to-digital converter. The computer processes the measurement data at 10 nanometer intervals across the visual spectrum, from 400 to 700 nanometers. For the color determination tests, the 10th CIÉ Standard Observer (CIÉ means Commission International de l'Eclairage, an international commission on lighting) was used. The "Standard Observer" is the spectral response characteristic of the average observer defined by the CIÉ . Two sets of data of this type are defined, the 1933 data for the 2nd visual field (distance view) and the 1964 data for the 10th annular visual field (approximately the arm length view). A much better agreement can be obtained with the average visual evaluation using the standard observer 10 ° and therefore this was the observer used in these tests. For each color sample tested, a sample was explored with the spectrophotometer. This exploration produced a numerical description of the colored sample, a digital print, which never changes. However, since it does not consider the lighting condition and the observer, the CIÉ L * a * b * n completely describes the visual aspect of the color. S developed a mathematical means to transfer digital impressions to a set of three numbers (XYZ), tristimulus values. The tristimulus values describe the color as a normal observer sees them under a specific lighting condition. Since the triestimulus (XYZ) values do not provide uniform or logical estimates of color intervals perceived color relationships, the scales based on the standard CIÉ observer were transformed into the theory d of the "opposing colors" of the color vision. The 1976 CIÉ L * a * b is one such transformation. The theory of the colored opponents maintains that the interaction between the eye and the brain decodes the experience of a color in three specific signals. One of these signals is light-dark (L *), a red-green e (a *) and one is yellow-blue (b *) «This color system was chosen for use in these tests because it is believed to be understandable to both the color expert and the novice. Thus, all the instrument's color readings were taken in a SPECTROPLUS spectrophotometer C.A.T., in Illuminant D65, with observer 10 °, in color space 1976 CIÉ L * a * b *.

Each sample tested was placed in the sample opening of the instrument. Two complete spectroeotometer readings (scans) were taken, completely emptying and repeating the layout procedure each time. The procedure was repeated until consistent readings were obtained within a range of less than 0.3 units. If not, the procedures were repeated with more attention to detail. All samples submitted to a spectrophotometer for the determination of the difference or color were at room temperature. Samples were read in all cases within four hours of printing (Samples that were left in an uncontrolled condition may present unwanted changes, and samples that were left to rest for a long period of time are not acceptable for readings in the spectrophotometer). When interpreting the results of the spectrophotometer, the opposing color scales give color measurements in units of approximate visual uniformity in the color space. L * measures clarity and ranges from 100 for perfect white to zero for black, approx. how the eye evaluates it; a * and b * chromaticity dimensions, give understandable color designations as follows: a * measure the degree of red when it is more, gray when it is zero, and the degree of green when it is less and b * measure the degree of yellow when it is more, gray when it is zero, and the degree of blue when it is less. The color change in the Examples here is reported as? E * 'which is defined as:? E * = [(? L *) 2 + (? A *) 2 + (Áb *) 2] where is it preferred? E * is as low as possible preferably not more than 10 after 500 hours of exposure to the weathering device, particularly preferably no more than 5 after 500 hours of exposure to the weather meter. The data for all Tables I-IV used the thermal mass transfer composition and donor element described in Example I printed on a retroreflective coating known under the trade designation 3M SCOTCHLITE reflective patent plate coating, product series 3750, which It was a retroreflective lens coating including a polyvinyl butyral binder layer in which are completely included glass beads, a reflective layer, aluminum, a PSA layer and a paper coating. In all Examples (Tables I-IV) block images were printed by thermal mass transfer on the exposed binder of the retroreflective coating using a Zebra 140 thermal mass transfer print, which can be obtained from Zebra Technologies Corp. Chicago, IL . The data for Tables I and III were generated with a layer of glass cover over the printed signs, while the data for Tables II and IV were generated with the sign printed with a cover layer of polymethyl methacrylate (PMMA), 0.003 inches (0.076 mm) thick. The articles were tested in duplicate with respect to the brightness and color change test. The retention of brightness in percent was determined for each sample by dividing the final values by the starting values by multiplying the result by 100.

EXAMPLES In Examples 1, 2 and 3 below, the thermal mass transfer donor elements consisted of a colored thermal mass transfer composition according to the invention adhered to a 4.5 micrometer thick PET film with a coating Anti-stick on his back. The PET film with an anti-stick coating was obtained from Toray Chemical Co., Japan Except where indicated, the thermal mass transfer composition was derived from an aqueous recoverable composition according to the invention comprising an acrylic dispersion carried by water obtained from BFGoodrich, Cleveland, Ohio, known under the commercial name CARBOSET 514H, a polyethylene emulsion known under the trade name POLYEMULSION 330 N35 obtained from Chemical Corporation of America, and at least one dispersion of pigments based on aqueous surfactants of Heucotech known under the trade name AQUIS II as detailed in every example. The compositions that can be coated were milled in a ball mill for at least 24 hours before they were coated to decrease the particle size to much less than micrometer and thus increase the light transparency of the printed compositions. The recoverable compositions were coated on the polyester film by means of a wound wire rod (other methods for depositing thin films, such as gravure printing, flexographic printing, and the like, can be used) and drying at elevated temperature at 80 ° C for 1 minute. The resulting coated vehicle film was attached to a color test donor element used in a color test machine known under the trade name RAINBOW DESKTOP COLOR PROOFER, which can be obtained from 3M. In Examples 1, 2 and 3 the donor element was placed in the tester and an image was printed by thermal mass transfer on a retroreflective coating precursor composed of glass beads completely included in polyvinyl butyral binder. The resolution was higher than 200 dots per inch (dpi), which indicated that the adherence to the retroreflective coating was good.

Example 1: A recoverable composition, according to the invention, was prepared as described above using the pigment dispersion known under the trade name Pigment Blue 15: 3 dispersed in a stabilized dispersion of aqueous Heubach surfactant (also known under the commercial name AQUIS II BW 3571 pigment 45%, solids 51%). The composition comprises a 1: 1: 4 weight ratio of PB 15: 3 dispersion / 514H / 330 N35 (10% solids in a 1: 1 weight ratio of ethanol / deionized water). The composition that can be coated according to the invention was coated on a 4.5 micrometer thick polyester film of Toray with a # 20 coiled wire rod to produce a thermal mass transfer composition layer of 3.3. micrometers thick (coloring layer). The film was attached to the test donor element and the thermal mass transfer composition of the invention was thermally transferred to the upper polyvinyl butyral film. The dye layer showed good adhesion to the polyvinyl butyral retroreflective coating precursor film and excellent transparency as defined by the following relationship: Transparency < x logio (I0 / I3) where IQ is the original light intensity and Is is the intensity of scattered light, and where the higher the value of the logarithm, the better the transparency. As a comparison of the transparency and optical transmission density (TOD) of the thermal mass transfer compositions of the invention with a known composition, three obtainable commercially available wax-based thermal transfer tapes were used. from Calcomp, Co. , Sanders Corp. of Anaheim, CA, to transfer a block of color to a PET film. Table A compares TOD (measured using a MacBeth densitometer TR927) and transparency (measured using a MacBeth RD918 analyzer) for the comparative images produced using the tapes of Example I. The data in Table A illustrates that although the images produced using the compositions of the invention and the heat transfer articles have higher transmission optical density (TOD) than the comparative example, the thermally transferred dough compositions of the invention showed greater transparency, an unexpectedly good result.

TABLE A Calcomp Dye Transfer Invention - Rency TOD Transparen- TOD Thermal Transparency Yellow 0.40 1.07 0.85 1.60 Magenta 0.53 1.51 0.85 1.69 greenish blue 0.81 1.39 2.73 1.93 Example 2 Example 1 was repeated with the following exceptions: a polyalkylene type binder precursor composed of i) a copolymer dispersion of ethylene acrylic acid (EAA) known under the trade name 50T4983 from Morto International (25% solids) and ii) a version Polymerized stearylmethacrylate hexanedioldiacrylate (SMA-HDDA), obtained as an aqueous dispersion of 3M, was used in place of the polyethylene dispersion; and the acrylic dispersion known under the trade name CARBOSET XL-11 from BFGoodrich was used in place of CARBOSET 514H.

The following recoverable composition was coated on a new piece of the same polyester vehicle used in Example 1 using a # 18 coiled wire rod to produce a 3 micron thick layer of thermal mass transfer composition (coloring layer ): a ratio of compositions (a) and (b) 1: 1 by weight, wherein a) ratio 1: 1 by weight of dispersion pB 15: 3 / 50T4983 (10% solids in a 4: 1 weight ratio of ethanol / deionized water + 1 weight percent NH40H) and b) 1: 1 weight ratio of SMA-HDDA (10% solids in deionized water / XL 11 (10% solids in a 4: 1 weight ratio of ethanol / water deionized)). The film was attached to the donor element used in the same color test machine used in Example I, and the thermal mass transfer composition of the invention was thermally transferred to the upper polyvinyl butyral film. The dye layer showed good adhesion to the retroreflective polyvinyl butyral precursor film and excellent transparency.Example 3 (four shots of color images on retroreflective coating) The retroreflective coating, the acrylic dispersion, and the polyethylene dispersion of Example I were used to prepare the following four recoverable compositions, according to the invention in the following proportions at 10 weight percent solids in a ratio of 1: 1 weight of ethanol / deionized water.

Color: Yellow Pigment used: AQUIS .II PY 150, also known as YW 3338, a solid pigment 35% by weight Composition that can be coated: weight ratio 1: 1: 4 dispersion PY 150 / CARBOSET 514H / POLY-EMULSION 330 N35 Color: Magenta Pigment used: AQUIS II PR 122, also known as RW 3115 Composition that can be coated: weight ratio 1: 1: 4 of PR 122 / CARBOSET 514H / POLYEMULSION 330 N35 Color: Blue green Pigment used: AQUIS II PB 15: 3, also known as BW 3571 Coatable composition: weight ratio 1: 1: 4 of PB 15: 3 / CARBOSET 514H / POLYEMULSION 330 N35 Color: Black Pigment used: AQUIS II PIGMENT BLACK (also known as KW 3750, a composition of solids 55% by weight) Composition that can be coated: 1: 1: 4 of PIGMENT BLACK / CARBOSET 514H / POLYEMULSION 330 N35 Each recoverable composition was coated on a separate 4.5 micron thick PET film having an anti-stick coating (Toray) using a # 20 coiled wire rod to produce a thermal mass transfer layer (dye layer) with a thickness of 3.3 micrometers. Each coated vehicle film was attached to the test donor element used in the tester described in Example I, each at its appropriate point. An image was prepared in such a way that when transferring dye was transferred to 100% energy because the test machine was not designed for thermal mass transfer. This limited the number of colors capable of being printed to red, magenta, blue, greenish-blue, green, yellow and black. Printing using a dot growth technique would undoubtedly produce more varied colors.

Test results with e "accelerated weathering device: brightness and color change As previously mentioned, the recoverable composition of Example 1 was prepared with various pigments, separate thermal mass transfer donor elements formed into separate pieces of the Toray PET film vehicle, and the thermal mass transfer compositions of the invention. were transferred by thermal mass as a color block to separate pieces of retroreflective coating known under the trade designation 3M SCOTCHLITE Reflective patent plate coating, 3750 series product, 3M. The color coatings were then subjected to the accelerated weather meter test and the brightness retention and color change was measured after 500 and, in some examples, 1000 hours. These data are presented in Tables, I-IV. in Tables I and II; the denomination AE * denotes the change of color as in the test described above, while in Tables III and IV the denomination "CPL" denotes candelas, per lux per square meter, which is a measure of brightness. As you can see from the data, the brightness retention was excellent in all samples (except black pigments, in which brightness is not a problem), and the color change was minimal or within acceptable values. The gloss retention is preferably at least 50 percent after 500 hours of testing with the accelerated weather meter, more preferably at least 75 percent after 1000 hours of testing with the accelerated weather meter. Various modifications and alterations of this invention will be apparent to those skilled in the art without departing from the scope thereof. It should be understood, therefore, that the scope of this invention should not be limited to the illustrative embodiments set forth herein, but is determined by the limitations expressed in the claims and equivalents thereof.

Table I (Color change - Images covered by glass) Table II (Color change - Images covered by PMMA film) Table III (Retention of brightness - Images covered by glass) Table IV (Retention of brightness - Images covered with PMMA film)

Claims (33)

1. A recoverable, film-forming, thermal mass precursor composition comprising: a) or "? Polyalkylene latex binder precursor, b) an acrylic latex binder precursor, c) an effective amount of a pigment to provide the desired color to a thermal mass transfer composition using the recoverable composition, and d) a diluent in which the polyalkylene binder precursor, the acrylic binder precursor and the pigment are all dispersed , characterized in that the pigment and the acrylic binder precursor are present in a weight ratio between pigment and acrylic binder precursor ranging from about 0.5: 1.0 to about 1.5: 1.0, and The polyalkylene binder precursor is present in an amount sufficient to provide the visible light and desired U transparency to the thermal mass transfer composition.

2. Composition according to claim 1, characterized in that the diluent comprises a significant portion of water.

3. Composition according to claim 1, characterized in that a combination of the polyalkylene latex, the acrylic latex and the diluent is substantially UV transparent.

4. Composition according to claim 1, characterized in that the polyalkylene binder precursor is selected from the group consisting of polyethylene, polypropylene, polybutadiene and oligomers and polyalkylene type polymers having a high percentage by weight of methylene units.

5. Composition according to claim 4, characterized in that the polyalkylene type oligomers and polymers having a high percentage by weight of methylene units are selected from the group consisting of compositions comprising the reaction product of a low molecular weight organic acid and a high molecular weight alcohol or short chain diol.

6. Composition according to claim 5, characterized in that the low molecular weight organic acid is methacrylic acid and the high molecular weight alcohol is stearyl alcohol.

7. Composition according to claim 5, characterized in that the low molecular weight organic acid is acrylic acid and the short chain diol is hexanediol.

8. Composition according to claim 1, characterized in that the acrylic binder precursor is selected from the group consisting of copolymers and terpolymers of an alkylene monomer and an acid copolymerizable monomer.

9. Composition according to claim 8, characterized in that the alkylene monomer is selected from the group consisting of ethylene and propylene.

10. Composition according to claim 1, characterized in that the acidic copolymerizable monomer is selected from the group consisting of acrylic acid, methacrylic acid and ethacrylic acid.

11. A thermal mass transfer donor element comprising a vehicle and a thermal mass transfer composition adhered to the vehicle, the thermal mass transfer composition comprising: a) a polyalkylene binder, b) an acrylic binder; and c) an effective amount of a pigment to provide the desired color to a more thermal transfer composition, characterized in that the pigment and the acrylic binder are present in a weight ratio between acrylic binder pigment ranging from ca. 0.5: 1.0 and approx. 1.5: 1.0, and the polyalkylene binder is present in an amount sufficient to provide the visible light and UV transparency and brightness desired to the thermal mass transfer composition.

12. A thermal mass transfer donor element according to claim 11, characterized in that the vehicle is a polymeric film.

13. A thermal mass transfer donor element according to claim 11, which is substantially UV transparent except for said pigment.

14. A thermal mass transfer donor element according to claim 11, characterized in that the polyalkylene binder is selected from the group consisting of polyethylene, polypropylene, polybutadiene and oligomers and polyalkylene type polymers having a high percentage by weight of methylene units.

15. A thermal mass transfer donor element according to claim 14, characterized in that the polyalkylene type oligomers and polymers having a high percentage by weight of methylene units are selected from the group consisting of compositions comprising the reaction product of an acid low molecular weight organic and a high molecular weight alcohol or short chain diol.

16. A thermal mass transfer donor element according to claim 15, characterized in that the low molecular weight organic acid is methacrylic acid and the high molecular weight alcohol is stearyl alcohol.

17. A thermal mass transfer donor element according to claim 15, characterized in that the low molecular weight organic acid is acrylic acid and the short chain diol is hexanediol.

18. A thermal mass transfer donor element according to claim 11, characterized in that the acrylic binder is selected from the group consisting of copolymers and terpolymers of an alkylene monomer and an acid copolymerizable monomer.

19. A thermal mass transfer donor element according to claim 18, characterized in that the alkylene monomer is selected from the group consisting of ethylene and propylene.

20. A mass transfer donor element: thermal according to claim 18, characterized in that the acid copolymerizable monomer is selected from the group consisting of acrylic acid, methacrylic acid and ethacrylic acid.

21. A signaling article comprising a thermal mass transfer composition in the form of signs adhered to a substrate, the thermal mass transfer composition comprising: a) a polyalkylene binder, b) an acrylic binder; and c) an effective amount of a pigment to provide the desired color to a thermal mass transfer composition, characterized in that the pigment and the acrylic binder are present in a weight ratio between pigment and acrylic binder ranging from ca. 0.5: 1.0 and approx. 1.5: 1.0, and the polyalkylene binder is present in an amount sufficient to provide the visible light and UV transparency and brightness desired to the thermal mass transfer composition.

22. Signaling article according to claim 21, characterized in that the substrate is selected from the group consisting of paper, metal, and polymeric materials.

23. Signaling article according to claim 22, characterized in that the polymer material is a polymer surface of a retroreflective coating.

24. Signaling article according to claim 23, characterized in that the polymer surface of a retroreflective coating comprises polyvinyl butyral.

25. Signaling article according to claim 23, characterized in that the signaling article is durable in the open air and resistant to weathering.

26. Signaling article according to claim 21, further comprising a layer of transparent covering material on the thermal mass transfer composition.

27. Signaling article according to claim 21, characterized in that the thermal mass transfer composition has a thickness ranging from about 1 to about 10 microns.

28. Signaling article according to claim 21, characterized in that the thermal mass transfer composition has a thickness ranging from about 2 to about 8 micrometers.

29. Signaling article according to claim 21, characterized in that the thermal mass transfer composition has a thickness ranging from about 3 to about 6 micrometers.

30. Signaling article according to claim 21, characterized in that the article presents a protected color change defined by? E * of not more than 5 after exposure for 500 hours.

31. Signaling article according to claim 21, characterized in that the article exhibits a protected gloss retention of at least 50 percent after exposure to the accelerated meteorological meter for 500 hours.

32. Signaling article according to claim 21, characterized in that the article exhibits a protected gloss retention of at least 75 percent after exposure to the accelerated meteorological meter for 1000 hours.

33. A method for formulating a film-forming composition, which can be coated, the composition being suitable for use to produce a thermal mass transfer-giving element, the method comprising the steps of: a) adding water to an amount of a dispersion of pigment using moderate agitation to form a first intermediate, b) adding methanol to the first intermediate to form a second intermediate, c) adding an acrylic dispersion to the second intermediate to form a third intermediate, and d) adding a polyalkylene emulsion to the third intermediate for forming the composition that can be coated, characterized in that the amount of water and methanol is sufficient to give the composition a weight percentage of solids ranging from about 1 to about 20 weight percent, and the pigment dispersion, the latex acrylic, and the polyalkylene emulsion are present in a weight ratio of approx. 1: 1: 4