Title:
HOT STAMP TAPE WITH ETCHED CARRIER
United States Patent 3770479
Abstract:
A web of indeterminate length carrying thermally transferable material, usually referred to as hot stamp tape, is structured to provide an improved simulated wood grain pattern on a substrate after transfer to the substrate of transferable portions of the tape. The web or tape may be provided in sheet form. A carrier sheet is etched to provide "ticks" or discrete linearly oriented spots of material having lower specular reflectivity than the remainder of the surface and a layer is coated thereon to provide the top layer of the transferred material, which replicates the surface of the carrier sheet. Either the tick areas or non-tick areas may be etched depending on the effect of the etchant and the characteristics of the unetched areas.
US Patent References:
Polyamide heat transfer for launderable fabrics
Meyer et al. - December 1967 - 3359127
Heat transfer
Shepherd - June 1961 - 2990311
Transfer and method of coating therewith
Francis - June 1951 - 2556078
Transfer picture and process for its manufacture
Hentschel - October 1932 - 1882593
Method of imitating wood and resulting products
Verne et al. - July 1936 - 2046954
Polyamide heat transfer for launderable fabrics
Meyer et al. - December 1967 - 3359127
Heat transfer
Shepherd - June 1961 - 2990311
Transfer and method of coating therewith
Francis - June 1951 - 2556078
Transfer picture and process for its manufacture
Hentschel - October 1932 - 1882593
Method of imitating wood and resulting products
Verne et al. - July 1936 - 2046954
Application Number:
05/257433
Publication Date:
11/06/1973
Filing Date:
05/26/1972
View Patent Images:
Export Citation:
Assignee:
Thermark Corporation (Schererville, IN)
Primary Class:
Other Classes:
428/209, 428/484.100, 428/211.100, 428/200, 427/152, 156/232, 428/480, 428/207
International Classes:
B44C1/17; B44C3/08; B44F9/00; B44F9/02; B44C3/00; B41M3/12; B44C1/16
Field of Search:
117/3.4,45,8,11 264/226,219 161/46T 156/61,231,238,240,2,232
US Patent References:
Primary Examiner:
Martin, William D.
Assistant Examiner:
Gwinnell, Harry J.
Parent Case Data:
CROSS-REFERENCES
This application is a continuation-in-part of application Ser. No. 188,423, filed Oct. 12, 1971, entitled "Hot Stamp Tape", now Pat. No. 3,666,516.
Claims:
Having thus described my invention, I claim
1. In a hot transfer sheet comprising a carrier sheet and transferable material on one side of said carrier sheet, said transferable material being releasable from said carrier sheet and said transferable material being adherently attachable to a substrate in response to heat and pressure, said hot transfer sheet characterized by the combination of
2. The sheet of claim 1 wherein said first surface of the carrier sheet is a matte surface.
3. The sheet of claim 1 wherein said heat transferable replicating layer comprises coloring material.
4. The sheet of claim 1 wherein said heat transferable replicating layer is transparent and is coated with at least one additional layer, said additional layer comprising coloring material.
5. The sheet of claim 1 wherein said heat transferable replicating layer is tacky when heated to provide adherence of said transferable material to said substrate when transferred in response to said heat and pressure.
6. The sheet of claim 1 wherein said transferable material includes an adherence layer to provide adherence to said substrate and said adherence layer consists essentially of a layer of material which provides a surface for said transfer sheet opposite to said second surface of said carrier sheet, said adherence layer of material being tacky when heated.
7. The sheet of claim 1 wherein said carrier sheet comprises a laminate and said laminate comprises a lamina of paper and a lamina of aluminum.
1. In a hot transfer sheet comprising a carrier sheet and transferable material on one side of said carrier sheet, said transferable material being releasable from said carrier sheet and said transferable material being adherently attachable to a substrate in response to heat and pressure, said hot transfer sheet characterized by the combination of
2. The sheet of claim 1 wherein said first surface of the carrier sheet is a matte surface.
3. The sheet of claim 1 wherein said heat transferable replicating layer comprises coloring material.
4. The sheet of claim 1 wherein said heat transferable replicating layer is transparent and is coated with at least one additional layer, said additional layer comprising coloring material.
5. The sheet of claim 1 wherein said heat transferable replicating layer is tacky when heated to provide adherence of said transferable material to said substrate when transferred in response to said heat and pressure.
6. The sheet of claim 1 wherein said transferable material includes an adherence layer to provide adherence to said substrate and said adherence layer consists essentially of a layer of material which provides a surface for said transfer sheet opposite to said second surface of said carrier sheet, said adherence layer of material being tacky when heated.
7. The sheet of claim 1 wherein said carrier sheet comprises a laminate and said laminate comprises a lamina of paper and a lamina of aluminum.
Description:
FIELD
This invention relates to hot stamp tapes and more particularly to webs comprising heat transferable coatings.
PRIOR ART
The instant invention represents an improvement on the disclosures of the following patents: U. S. Pat. Nos. 3,592,722, Morgan; 3,486,919, Dreazy et al., 3,467,538, Best; 3,459,626, Morgan; 3,434,862, Luc; 3,363,956, Vingren et al., 3,351,510, Harris; 3,252,847, Morgan; 3,054,715, White; 2,316,143, Peebles et al.; 2,303,395, Schultz et al.; 2,046,954, Verne et al.; 2,016,416, Dippel; 1,844,083, Weber; and British Pat. No. 702,572, Ganz.
SUMMARY
Simulated woodgrain patterns have been provided on many surfaces in recent years. Examples include countertops, wall panels, cupboard door, radio cabinets and the like. Many of these have been provided by printing a woodgrain pattern on paper, laminating the paper to a substrate and covering the paper with a layer of synthetic resinous material. This has been particularly true in the case of countertops and wall panels.
In other instances, a woodgrain pattern has been provided in a transferable layer of a hot stamp tape (or web) and then, by hot stamp transfer, the transferable portion including the woodgrain patterned layer has been transferred to and adhered to a substrate.
More recently, in order to better simulate the grain of wood, it has become common to emboss linearly oriented spaced-apart depressions into the surface during or after transfer, the embossed portions being referred to in the art as "ticks." Alternatively it has been well-known to provide the substrate with such "ticks" by molding or embossment prior to applying a coating thereto and then forcing the coating down into the "ticks."
Even more recently, hot stamp tapes have been provided in which ticks were printed on a carrier with a "rotten" or splitting ink prior to applying the transferable layers to the carrier so that when the transferable portion was transferred in response to heat and pressure, a portion of the splitting ink remained on the carrier in each tick area and a second portion was transferred in each tick area.
More recently yet, improved results have been obtained as described in the parent application hereto, now U.S. Pat. No. 3,666,516 by applying a non-transferable tick coating to the carrier and applying thereto as a portion on in some instances the entirety of the transferable material, a replicating layer which replicates the coated tick portions as well as the remainder of the carrier sheet surface.
In accordance with the present invention, the carrier sheet is etched to provide tick portions which are less specularly reflective than remaining or non-tick surface portions of the carrier sheet so that the tick areas and non-tick areas respectively differ markedly in specular reflectivity to provide in the final product an excellent simulation of the grain patterns of actual wood.
I first provide a carrier sheet or web which may be any carrier sheet or web of the prior art; for example, a polyester film such as "Mylar" (trademark of DuPont), "Melinex" (trademark of Imperial Chemical Industries), or a web of cellophane or cellulose acetate or paper or a laminate as described below. I may utilize either paper, such as a heavily filled paper as described below or a paper laminate such as an aluminum paper laminate or a polyester film, particularly "Mylar." A matte-surfaced Mylar may be provided by incorporating an inert particulate substance in the formulation during early stages of manufacture which affects the surface during later biaxial orientation or by embossment or abrading or chemical coating such as by applying to a glossy Mylar surface a coating which provides a matte surface.
The carrier may then be etched on one surface to provide "ticks" so that the surface of each "tick" is a surface having very low specular reflectance. The area eteched may either be the tick areas or the non-tick areas. Thus, if the carrier has a matte surface suitable to consititute the surface of tick portions, the remainder or non-tick areas may be etched with an etchant which reduces the degree of matte (increases specular reflectance, increases gloss) to provide a desired result. Etchant may be applied by any suitable means such as by silk screening or spraying through a mask or by gravure printing or printing from the surfaces of characters (letter press) or by first applying a "resist" coating by any such means, the "resist" coating being impervious or resistant to the etchant, then applying the etchant, then stopping the washing off the etchant and then, in most instances, removing the resist. In some instances, if a resist coating is used, it may not be necessary to remove the resist subsequently or it may not be necessary to wash to remove the etchant. In some instances neither step may be necessary. The discrete spaced apart portions or tick areas are an integral portion of the carrier sheet so that they will not transfer from the carrier sheet when subjected to the heat and pressure of the transfer operation.
A release coating may then be applied which may be of conventional form and may thus be based on paraffin wax or the like. The normal characteristics of a release coating are that it melts or softens at a temperature below that of other layers in the sheet so that neither the carrier portion which remains behind or the transferred portion (which may be one layer or may be as many as eight or 10 layers) is melted or softened, except that the surface of the layer adjacent the substrate is sufficiently softened or made sufficiently tacky to provide adherence to the substrate.
Extreme thinness of the release coating is absolutely essential if not entirely critical. Thus, the release coating must be relatively thin relative to the size of the "bumps" in the relatively non-specularly reflective surface of the tick areas, to permit subsequent replication of these "bumps" as well as subsequent replication of the "bumps," if any, of the non-tick area.
A layer of replicating synthetic resinous material is then coated relatively thickly over the release coating so that the dimensions of said "bumps" in each tick area are either somewhat less or at least not much greater than the thickness of this newly coated layer, the newly coated layer being of synthetic resinuous material suited to replicate both etched and un-etched portions of the surface of the carrier sheet. This replicating layer may carry coloring material or may be transparent and may be adapted to be adhered directly to a substrate or may be provided with additional layers which may comprise coloring material and/or tackiness characteristics for providing adherence to a substrate. The replicating layer may be provided with release properties so that the aforementioned release coat is not necessary and may be omitted, as described below in greater detail.
For example, it is normal to provide a simulated wood-grain pattern as a plurality of printings of different colors overlying each other and a coating is necessary for each such color. Coatings embodying all these colors may be placed over the replicating coating and the last of such color-containing coatings or an additional coating may be of a composition that provides the desired degree of tackiness during heat transfer to provide adhesion to the substrate.
Although carrier sheets either having a high degree of specular reflectivity, that is, being highly glossy or having a matte surface, that is, having a lower degree of specular reflectivity, have been described, the carrier sheet surface may have any suitable degree of specular reflectivity desired for any particular purpose.
This invention is not limited to providing simulated woodgrain patterns but may be utilized to provide any desired pattern having coated surface portions which vary greatly in specular reflectivity. Thus, on a carrier sheet having high, medium or low specular reflectivity, there may be etched not only one group of "ticks" or other pattern having a particular set of surface characteristics, but there may also be etched additional groups of "ticks" or other patterns to provide any desired number of groups, each group having a particular surface characteristic or characteristics which need not be the same as that of any other group etched thereon.
The replicatory coat then replicates all cahracteristics of all the etched, partially etched (if any) and un-etched portions of the carrier sheet surface.
OBJECTS
It is, therefore, an object to provide a hot stamp tape or web suitable for providing an improved simulated woodgrain pattern on a substrate.
Another object is such a web etched to provide tick areas having low specular reflectivity and a replicating coating adapted to provide portions having corresponding low specular reflectivity after transfer.
Another object is to provide such a replicatory coat with two different degrees of reduced specular reflectivity after transfer.
Further objects will become apparent from the description.
DRAWINGS
In the drawings like reference numerals refer to like parts and:
FIG. 1 is a cross-sectional schematic view of one embodiment of the method and article of the invention;
FIG. 2 is a cross-sectional schematic view of the embodiment of FIG. 1 after completion of the process;
FIG. 3 is a cross-sectional schematic view of another embodiment of the process and article; and
FIG. 4 is a cross-sectional schematic view of the embodiment of FIG. 3 after completiom of the process.
DESCRIPTION
Referring now to FIG. 1, a carrier sheet A may be provided with etched tick areas 9. A release coat D may then be provided and overlying the release coat there may be provided respectively a replicating layer E, an abrasion resistant layer F, a second abrasion resistant layer G, a color coat H, another color coat I, and an adherence promoting coat J.
Heat as indicated by arrows 10 and pressure as indicated by arrows 11 may be applied to force the laminar assembly 13, consisting of layers A through J as described, against substrate 14. After thus applying heat and pressure, the carrier sheet and layers B and C and D attached thereto, may be removed to provide the article of FIG. 2, wherein areas of low specular reflectance are indicated at 15 and areas of specular reflectance differing therefrom are indicated at 16.
In FIG. 3 is shown an embodiment corresponding to that of FIG. 1 wherein many layers are omitted, layer E provides a combination replicating, release, color, and adherence coat. In FIG. 4 is shown the article which remains after completing the process of FIG. 3 and removing sheet A having coating C attached thereto.
Etchant or resist and also color layers such as H and I may be applied by gravure printing or applied by silk screen printing, letter press printing, or the like. All other coats or layers may be applied by any suitable coating means such as by Meyer rod or roller coater.
Below are given specific examples of suitable formulations for each coating layer together with particular characteristics thereof.
The carrier sheet which is preferably in web or tape form may be, as described above, a polyester film such as Mylar or a web of cellophane or cellulose acetate or paper. Mylar having a thickness of from one-half mil to 2 mils is preferred.
Table I below sets forth pertinent data on carrier material, carrier surface, resist and etchant for each of 13 examples. In Table II are shown the layers present in the various examples.
The release coat is generally preferably of a material such as a wax or the like; either natural wax, paraffin wax, or a mixture thereof, or a mixture of wax with other substances, may be used; but it is generally a waxy substance characterized by having a softening range rather than a clear softening point. The softening range or softening point of the release coat is generally preferably lower than the melting or softening points of the carrier sheet and all other layers in the laminar assembly so that when subjected to heat the softness of the release coat when heated permits the replicating coat to be released therefrom.
The replicating coat may in suitable instances be provided with release properties so that when subjected to suitable heat and pressure during hot stamping it is suitably released from the carrier sheet without the presence of a separate and a distinct release coat.
Abrasion resisting coats have the obvious function of providing enhanced abrasion resistance and either or both may be omitted if the replicating layer provides sufficient abrasion resistance in and of itself. Color coats are generally printed on. Generally at least two color coats are necessary if a suitable wood grain or simulated wood grain pattern is to be provided and often three color coats may suitably be utilized for the purpose of providing an attractive and suitable simulated wood grain pattern; however, for providing other patterns which are not simulated wood grain patterns, it may in many instances be suitable to provide only a single color coat or to provide sufficient coloring material in the replicating layer so that no individual color coat is necessary. In some instances, in fact, if no color is desired in the surface finish, no coloring material at all need be incorporated. The purpose of the adherence layer is to promote or improve adherence of the laminar assembly to a substrate, and an adherence coat need be provided only if the adherence is otherwise unsatisfactory.
Whereas the examples show the use of only one thickness of cellulose acetate film, such film may be used which has a thickness of from 0.8 to 3.0 mils.
In each example, the effect of the etchant is to reduce rather than increase the degree of matte, that is, the effect is to increase the specular reflectivity or glossiness. With such etchants it is preferred, for the purpose of providing hot stamp tapes to simulate wood grain patterns, to apply the etchant to all those areas not occupied by ticks and to let the matte surface originally present be the surface of the carrier in the tick areas. With other etchants and other carriers, where the etchant provides a less glossy surface than that originally present, it is, of course, preferable to apply the etchant only in the tick areas if a hot stamp tape is to be provided to simulate a wood grain pattern.
The resist used in the examples is removed by washing with acetone or other solvent for the resist which is non-solvent for cellulose acetate.
If the same resist, i.e., one-half sec. R. S. Nitrocellulose, is used on a different carrier material, e.g., polystyrene, it may then be removed by mechanical means, viz., brushing and blowing with a strong air current. Other mechanical means might be substituted, e.g., vacuum and scraping.
With other resists on other carriers the resist may usually be dissolved or washed away.
Although the examples show only the use of cellulose acetate as a carrier, Mylar may be used as a carrier in accordance with the invention and has been successfully etched with etchants known in the art or discovered long heretofore.
Mylar may be provided and possibly may be utilized as a carrier in thicknesses of from about 0.2 to 0.3 mil to 2.0 or 3.0 mils but generally when Mylar is used as a carrier, a thickness of 0.5 or 1 mil is usually used.
Generally etchants for Mylar produce a relatively pronounced matte effect and decrease the specular reflectivity or glossiness.
Matte surfaced Mylar may be provided by abrading or by manufacturing with an inert material included in the formulation which provides the desired matte surface during the subsequent step in manufacture of bilateral stretching to provide bilateral orientation. Mylar with an overall matte surface may also be provided by etching with such an etchant as may be applied as disclosed herein to provide discrete tick areas; it may also be provided by coating with any formulation described in the aforementioned parent application for a tick coat. The degree of matte, that is, the amount of reflectivity of the surface may be controlled, in this latter instance by controlling the proportion of flattener in the coating formulation. If a coating is thus used to provide a matte surface, it is of course preferred to choose a coating which is not resistant to the etchant, that is, one which may be etched. However, on the other hand, such a coating may be used as a resist which is allowed to remain in place after etching and may be applied by any suitable printing technique to cover these areas which are not to be etched and expose the Mylar surface in those areas which it is desired to etch and in this latter instance it is desirable that a coating formulation be selected which is resistant to (unetched by or relatively unetched by) the etchant chosen.
Also, although the examples show only cellulose acetate film as a carrier, a laminate of paper and aluminum foil may be used as a carrier in accordance with the invention. Generally the layer of aluminum is nominally 0.00023 inch or 0.00035 inch thick, though such laminates which incorporate thicker layers of aluminum may suitably be used. The finish on the aluminum surface as it is provided prior to etching is generally provided by finishing rolls during the process of manufacture and may be a relatively glossy surface or a slightly matte surface. Etchants may be those such as used in the chemical milling of aluminum and may be suitably compounded to provide the degree of matte desired and a viscosity or range of viscosities suitable for application by the chosen method such as gravure printing, letter press or raised character printing or silk screen printing where the etchant is to be applied directly only to those areas to be etched or by Meyer rod or roller coater in those instances in which a resist is utilized. Such etchants are usually caustic in nature and may comprise NaOH, KOH or the like. To provide a suitable viscosity a thickener may be added; for example, to thicken solutions of NaOH having a concentration of up to 50 percent NaOH, a modified bentonite clay sold commercially under the trademark "Bentone LT" by the National Lead Company may be added in concentration of from 0.5 percent to 4 percent. Such etchants may generally be stopped and washed with water.
It may be suitable to utilize as a resist, on the aluminum surface, any one of many traditional types of resist compositions in the etching art which are generally based on shellac, pitch, asphalt or other bituminous material and the like. Such resists are generally used as being resistant to etching acids but may in many instances be utilized in accordance with the present invention as being appreciably more resistant to caustics than is aluminum.
A resist, if used, may be allowed to remain on the carrier if its adherence to the carrier is suitable and the degree of specular reflectivity of its surface is suitable, rather than being removed before application of the replicating layer. The resist, if allowed thus to remain, then becomes part of the carrier, that is, part of the non-transferable portion of the structure; its surface constitutes the unetched portion of the carrier which is replicated by the replicatory layer.
A suitable resist coat which may be allowed to remain on the aluminum after etching, rather than being removed prior to application of the replicating layer may be suitably formulated composition comprising an epoxy resin or an acrylic resin.
In place of Mylar or cellulose acetate or other resin film or paper-aluminum laminate there may be utilized as a carrier a sheet or web of paper provided with a suitable surface treatment. Thus there may be utilized a 15 lbs. high strength bleached kraft treated with or provided with a coating of high solids content modified thermosetting acrylic resin. A suitable such resin may be Crystophane, trademark of International Printing Ink Corp., resin.
A polystyrene film which may be used as a carrier may be etched with an etchant such as toluol. A suitable polystyrene film may be an oriented polystyrene film sold under the trademark "Tricite" by Dow Chemical Company.
A laminate of polystyrene and paper may also be utilized as a carrier in accordance with the invention.
To provide a suitable viscosity for the etchant to facilitate its application it is generally most suitable to add a thickener such as the thickeners disclosed below for methylethylketone, ethylene dichloride and NaOH solutions. Thickeners for organic and agneous liquids are generally well known in the art and any may be used which are suitable. Examples of well known thickeners include pyrolytic silica such as that sold under the trademark "Cabosil" by Cabot, bentonite clays, derivatives of hydroxy ethyl cellulose, carboxy methyl cellulose and soaps or metal salts of fatty acids.
A resist (resist coat or resist layer) is normally removed after applying the etchant and prior to applying the replicating layer. However, as previously mentioned, the resist may be allowed to remain in place if its adhesion to the carrier is suitable and other properties are suitable so that it is not transferred when heat and pressure are subsequently applied to transfer the transferable portion; it becomes part of the non-transferable portion and thus part of the carrier when applied.
In other embodiments the resist may be allowed to remain in place after application of the etchant and prior to application of the replicating coat but it may be formulated so that it releases from the carrier and adheres to the replicating layer so that it becomes part of the replicating layer. For example, any one of the replicating formulations of Examples 5 and 7 through 13 may be used as a resist on Mylar, if its resistance to the etchant is suitable, and if then the same formulation is used for the replicating layer, the resist and replicating layers become undistinguishably part of the same layer and the unetched portion of the carrier is in fact replicated by that portion of the ultimate replicating layer which was originally applied as the resist.
In yet another series of embodiments, such a resist may be used and etching may be accomplished by abrading with fine particles. The fine particles (which may be sand, corncob particles, pecan or other nut shells, sawdust or any of a wide variety of materials) are forcefully directed against the surface by air blast, water blast or centrifugal throwing means and suitably abrade both the resist and the portions of the carrier which aren't covered by the resist. When a replicating layer of the same material (or similar material) as the resist is applied the resist and replicating layers become a single layer of replicating material and the abraded surface of the resist to which the replicating layer adheres entirely vanishes in the interior of the ultimately provided replicating material. As a specific example, any of the replicating layers of examples 5 through 13 may be used as a resist on Mylar for this purpose; in each instance, after etching by abrasion, the same material used as resist may be applied as a replicating layer. The resist then becomes part of the replicating layer, replicates the unetched portion of the Mylar to which it was applied, and transfers during heat and pressure transfer along with all other transferable material. ##SPC1##
In Table II, the presence of an X in a column indicates that a coating or layer is present in the example heading the column, and the absence of an X indicates the absence of a corresponding layer. ##SPC2##
Examples 1 to 8 are suitable for providing two-color patterns, if the color coats are printed, which may be simulated wood-grain patterns, simulated leather patterns and the like.
Although the examples show the presence of a release coat in all instances, a release need not necessarily be used in every case as made clear in connection with the drawings. ##SPC3## ##SPC4## ##SPC5## ##SPC6## ##SPC7##
Further embodiments and variations will be apparent to those skilled in the art and are intended to be included within the scope of the invention.
This invention relates to hot stamp tapes and more particularly to webs comprising heat transferable coatings.
PRIOR ART
The instant invention represents an improvement on the disclosures of the following patents: U. S. Pat. Nos. 3,592,722, Morgan; 3,486,919, Dreazy et al., 3,467,538, Best; 3,459,626, Morgan; 3,434,862, Luc; 3,363,956, Vingren et al., 3,351,510, Harris; 3,252,847, Morgan; 3,054,715, White; 2,316,143, Peebles et al.; 2,303,395, Schultz et al.; 2,046,954, Verne et al.; 2,016,416, Dippel; 1,844,083, Weber; and British Pat. No. 702,572, Ganz.
SUMMARY
Simulated woodgrain patterns have been provided on many surfaces in recent years. Examples include countertops, wall panels, cupboard door, radio cabinets and the like. Many of these have been provided by printing a woodgrain pattern on paper, laminating the paper to a substrate and covering the paper with a layer of synthetic resinous material. This has been particularly true in the case of countertops and wall panels.
In other instances, a woodgrain pattern has been provided in a transferable layer of a hot stamp tape (or web) and then, by hot stamp transfer, the transferable portion including the woodgrain patterned layer has been transferred to and adhered to a substrate.
More recently, in order to better simulate the grain of wood, it has become common to emboss linearly oriented spaced-apart depressions into the surface during or after transfer, the embossed portions being referred to in the art as "ticks." Alternatively it has been well-known to provide the substrate with such "ticks" by molding or embossment prior to applying a coating thereto and then forcing the coating down into the "ticks."
Even more recently, hot stamp tapes have been provided in which ticks were printed on a carrier with a "rotten" or splitting ink prior to applying the transferable layers to the carrier so that when the transferable portion was transferred in response to heat and pressure, a portion of the splitting ink remained on the carrier in each tick area and a second portion was transferred in each tick area.
More recently yet, improved results have been obtained as described in the parent application hereto, now U.S. Pat. No. 3,666,516 by applying a non-transferable tick coating to the carrier and applying thereto as a portion on in some instances the entirety of the transferable material, a replicating layer which replicates the coated tick portions as well as the remainder of the carrier sheet surface.
In accordance with the present invention, the carrier sheet is etched to provide tick portions which are less specularly reflective than remaining or non-tick surface portions of the carrier sheet so that the tick areas and non-tick areas respectively differ markedly in specular reflectivity to provide in the final product an excellent simulation of the grain patterns of actual wood.
I first provide a carrier sheet or web which may be any carrier sheet or web of the prior art; for example, a polyester film such as "Mylar" (trademark of DuPont), "Melinex" (trademark of Imperial Chemical Industries), or a web of cellophane or cellulose acetate or paper or a laminate as described below. I may utilize either paper, such as a heavily filled paper as described below or a paper laminate such as an aluminum paper laminate or a polyester film, particularly "Mylar." A matte-surfaced Mylar may be provided by incorporating an inert particulate substance in the formulation during early stages of manufacture which affects the surface during later biaxial orientation or by embossment or abrading or chemical coating such as by applying to a glossy Mylar surface a coating which provides a matte surface.
The carrier may then be etched on one surface to provide "ticks" so that the surface of each "tick" is a surface having very low specular reflectance. The area eteched may either be the tick areas or the non-tick areas. Thus, if the carrier has a matte surface suitable to consititute the surface of tick portions, the remainder or non-tick areas may be etched with an etchant which reduces the degree of matte (increases specular reflectance, increases gloss) to provide a desired result. Etchant may be applied by any suitable means such as by silk screening or spraying through a mask or by gravure printing or printing from the surfaces of characters (letter press) or by first applying a "resist" coating by any such means, the "resist" coating being impervious or resistant to the etchant, then applying the etchant, then stopping the washing off the etchant and then, in most instances, removing the resist. In some instances, if a resist coating is used, it may not be necessary to remove the resist subsequently or it may not be necessary to wash to remove the etchant. In some instances neither step may be necessary. The discrete spaced apart portions or tick areas are an integral portion of the carrier sheet so that they will not transfer from the carrier sheet when subjected to the heat and pressure of the transfer operation.
A release coating may then be applied which may be of conventional form and may thus be based on paraffin wax or the like. The normal characteristics of a release coating are that it melts or softens at a temperature below that of other layers in the sheet so that neither the carrier portion which remains behind or the transferred portion (which may be one layer or may be as many as eight or 10 layers) is melted or softened, except that the surface of the layer adjacent the substrate is sufficiently softened or made sufficiently tacky to provide adherence to the substrate.
Extreme thinness of the release coating is absolutely essential if not entirely critical. Thus, the release coating must be relatively thin relative to the size of the "bumps" in the relatively non-specularly reflective surface of the tick areas, to permit subsequent replication of these "bumps" as well as subsequent replication of the "bumps," if any, of the non-tick area.
A layer of replicating synthetic resinous material is then coated relatively thickly over the release coating so that the dimensions of said "bumps" in each tick area are either somewhat less or at least not much greater than the thickness of this newly coated layer, the newly coated layer being of synthetic resinuous material suited to replicate both etched and un-etched portions of the surface of the carrier sheet. This replicating layer may carry coloring material or may be transparent and may be adapted to be adhered directly to a substrate or may be provided with additional layers which may comprise coloring material and/or tackiness characteristics for providing adherence to a substrate. The replicating layer may be provided with release properties so that the aforementioned release coat is not necessary and may be omitted, as described below in greater detail.
For example, it is normal to provide a simulated wood-grain pattern as a plurality of printings of different colors overlying each other and a coating is necessary for each such color. Coatings embodying all these colors may be placed over the replicating coating and the last of such color-containing coatings or an additional coating may be of a composition that provides the desired degree of tackiness during heat transfer to provide adhesion to the substrate.
Although carrier sheets either having a high degree of specular reflectivity, that is, being highly glossy or having a matte surface, that is, having a lower degree of specular reflectivity, have been described, the carrier sheet surface may have any suitable degree of specular reflectivity desired for any particular purpose.
This invention is not limited to providing simulated woodgrain patterns but may be utilized to provide any desired pattern having coated surface portions which vary greatly in specular reflectivity. Thus, on a carrier sheet having high, medium or low specular reflectivity, there may be etched not only one group of "ticks" or other pattern having a particular set of surface characteristics, but there may also be etched additional groups of "ticks" or other patterns to provide any desired number of groups, each group having a particular surface characteristic or characteristics which need not be the same as that of any other group etched thereon.
The replicatory coat then replicates all cahracteristics of all the etched, partially etched (if any) and un-etched portions of the carrier sheet surface.
OBJECTS
It is, therefore, an object to provide a hot stamp tape or web suitable for providing an improved simulated woodgrain pattern on a substrate.
Another object is such a web etched to provide tick areas having low specular reflectivity and a replicating coating adapted to provide portions having corresponding low specular reflectivity after transfer.
Another object is to provide such a replicatory coat with two different degrees of reduced specular reflectivity after transfer.
Further objects will become apparent from the description.
DRAWINGS
In the drawings like reference numerals refer to like parts and:
FIG. 1 is a cross-sectional schematic view of one embodiment of the method and article of the invention;
FIG. 2 is a cross-sectional schematic view of the embodiment of FIG. 1 after completion of the process;
FIG. 3 is a cross-sectional schematic view of another embodiment of the process and article; and
FIG. 4 is a cross-sectional schematic view of the embodiment of FIG. 3 after completiom of the process.
DESCRIPTION
Referring now to FIG. 1, a carrier sheet A may be provided with etched tick areas 9. A release coat D may then be provided and overlying the release coat there may be provided respectively a replicating layer E, an abrasion resistant layer F, a second abrasion resistant layer G, a color coat H, another color coat I, and an adherence promoting coat J.
Heat as indicated by arrows 10 and pressure as indicated by arrows 11 may be applied to force the laminar assembly 13, consisting of layers A through J as described, against substrate 14. After thus applying heat and pressure, the carrier sheet and layers B and C and D attached thereto, may be removed to provide the article of FIG. 2, wherein areas of low specular reflectance are indicated at 15 and areas of specular reflectance differing therefrom are indicated at 16.
In FIG. 3 is shown an embodiment corresponding to that of FIG. 1 wherein many layers are omitted, layer E provides a combination replicating, release, color, and adherence coat. In FIG. 4 is shown the article which remains after completing the process of FIG. 3 and removing sheet A having coating C attached thereto.
Etchant or resist and also color layers such as H and I may be applied by gravure printing or applied by silk screen printing, letter press printing, or the like. All other coats or layers may be applied by any suitable coating means such as by Meyer rod or roller coater.
Below are given specific examples of suitable formulations for each coating layer together with particular characteristics thereof.
The carrier sheet which is preferably in web or tape form may be, as described above, a polyester film such as Mylar or a web of cellophane or cellulose acetate or paper. Mylar having a thickness of from one-half mil to 2 mils is preferred.
Table I below sets forth pertinent data on carrier material, carrier surface, resist and etchant for each of 13 examples. In Table II are shown the layers present in the various examples.
The release coat is generally preferably of a material such as a wax or the like; either natural wax, paraffin wax, or a mixture thereof, or a mixture of wax with other substances, may be used; but it is generally a waxy substance characterized by having a softening range rather than a clear softening point. The softening range or softening point of the release coat is generally preferably lower than the melting or softening points of the carrier sheet and all other layers in the laminar assembly so that when subjected to heat the softness of the release coat when heated permits the replicating coat to be released therefrom.
The replicating coat may in suitable instances be provided with release properties so that when subjected to suitable heat and pressure during hot stamping it is suitably released from the carrier sheet without the presence of a separate and a distinct release coat.
Abrasion resisting coats have the obvious function of providing enhanced abrasion resistance and either or both may be omitted if the replicating layer provides sufficient abrasion resistance in and of itself. Color coats are generally printed on. Generally at least two color coats are necessary if a suitable wood grain or simulated wood grain pattern is to be provided and often three color coats may suitably be utilized for the purpose of providing an attractive and suitable simulated wood grain pattern; however, for providing other patterns which are not simulated wood grain patterns, it may in many instances be suitable to provide only a single color coat or to provide sufficient coloring material in the replicating layer so that no individual color coat is necessary. In some instances, in fact, if no color is desired in the surface finish, no coloring material at all need be incorporated. The purpose of the adherence layer is to promote or improve adherence of the laminar assembly to a substrate, and an adherence coat need be provided only if the adherence is otherwise unsatisfactory.
Whereas the examples show the use of only one thickness of cellulose acetate film, such film may be used which has a thickness of from 0.8 to 3.0 mils.
In each example, the effect of the etchant is to reduce rather than increase the degree of matte, that is, the effect is to increase the specular reflectivity or glossiness. With such etchants it is preferred, for the purpose of providing hot stamp tapes to simulate wood grain patterns, to apply the etchant to all those areas not occupied by ticks and to let the matte surface originally present be the surface of the carrier in the tick areas. With other etchants and other carriers, where the etchant provides a less glossy surface than that originally present, it is, of course, preferable to apply the etchant only in the tick areas if a hot stamp tape is to be provided to simulate a wood grain pattern.
The resist used in the examples is removed by washing with acetone or other solvent for the resist which is non-solvent for cellulose acetate.
If the same resist, i.e., one-half sec. R. S. Nitrocellulose, is used on a different carrier material, e.g., polystyrene, it may then be removed by mechanical means, viz., brushing and blowing with a strong air current. Other mechanical means might be substituted, e.g., vacuum and scraping.
With other resists on other carriers the resist may usually be dissolved or washed away.
Although the examples show only the use of cellulose acetate as a carrier, Mylar may be used as a carrier in accordance with the invention and has been successfully etched with etchants known in the art or discovered long heretofore.
Mylar may be provided and possibly may be utilized as a carrier in thicknesses of from about 0.2 to 0.3 mil to 2.0 or 3.0 mils but generally when Mylar is used as a carrier, a thickness of 0.5 or 1 mil is usually used.
Generally etchants for Mylar produce a relatively pronounced matte effect and decrease the specular reflectivity or glossiness.
Matte surfaced Mylar may be provided by abrading or by manufacturing with an inert material included in the formulation which provides the desired matte surface during the subsequent step in manufacture of bilateral stretching to provide bilateral orientation. Mylar with an overall matte surface may also be provided by etching with such an etchant as may be applied as disclosed herein to provide discrete tick areas; it may also be provided by coating with any formulation described in the aforementioned parent application for a tick coat. The degree of matte, that is, the amount of reflectivity of the surface may be controlled, in this latter instance by controlling the proportion of flattener in the coating formulation. If a coating is thus used to provide a matte surface, it is of course preferred to choose a coating which is not resistant to the etchant, that is, one which may be etched. However, on the other hand, such a coating may be used as a resist which is allowed to remain in place after etching and may be applied by any suitable printing technique to cover these areas which are not to be etched and expose the Mylar surface in those areas which it is desired to etch and in this latter instance it is desirable that a coating formulation be selected which is resistant to (unetched by or relatively unetched by) the etchant chosen.
Also, although the examples show only cellulose acetate film as a carrier, a laminate of paper and aluminum foil may be used as a carrier in accordance with the invention. Generally the layer of aluminum is nominally 0.00023 inch or 0.00035 inch thick, though such laminates which incorporate thicker layers of aluminum may suitably be used. The finish on the aluminum surface as it is provided prior to etching is generally provided by finishing rolls during the process of manufacture and may be a relatively glossy surface or a slightly matte surface. Etchants may be those such as used in the chemical milling of aluminum and may be suitably compounded to provide the degree of matte desired and a viscosity or range of viscosities suitable for application by the chosen method such as gravure printing, letter press or raised character printing or silk screen printing where the etchant is to be applied directly only to those areas to be etched or by Meyer rod or roller coater in those instances in which a resist is utilized. Such etchants are usually caustic in nature and may comprise NaOH, KOH or the like. To provide a suitable viscosity a thickener may be added; for example, to thicken solutions of NaOH having a concentration of up to 50 percent NaOH, a modified bentonite clay sold commercially under the trademark "Bentone LT" by the National Lead Company may be added in concentration of from 0.5 percent to 4 percent. Such etchants may generally be stopped and washed with water.
It may be suitable to utilize as a resist, on the aluminum surface, any one of many traditional types of resist compositions in the etching art which are generally based on shellac, pitch, asphalt or other bituminous material and the like. Such resists are generally used as being resistant to etching acids but may in many instances be utilized in accordance with the present invention as being appreciably more resistant to caustics than is aluminum.
A resist, if used, may be allowed to remain on the carrier if its adherence to the carrier is suitable and the degree of specular reflectivity of its surface is suitable, rather than being removed before application of the replicating layer. The resist, if allowed thus to remain, then becomes part of the carrier, that is, part of the non-transferable portion of the structure; its surface constitutes the unetched portion of the carrier which is replicated by the replicatory layer.
A suitable resist coat which may be allowed to remain on the aluminum after etching, rather than being removed prior to application of the replicating layer may be suitably formulated composition comprising an epoxy resin or an acrylic resin.
In place of Mylar or cellulose acetate or other resin film or paper-aluminum laminate there may be utilized as a carrier a sheet or web of paper provided with a suitable surface treatment. Thus there may be utilized a 15 lbs. high strength bleached kraft treated with or provided with a coating of high solids content modified thermosetting acrylic resin. A suitable such resin may be Crystophane, trademark of International Printing Ink Corp., resin.
A polystyrene film which may be used as a carrier may be etched with an etchant such as toluol. A suitable polystyrene film may be an oriented polystyrene film sold under the trademark "Tricite" by Dow Chemical Company.
A laminate of polystyrene and paper may also be utilized as a carrier in accordance with the invention.
To provide a suitable viscosity for the etchant to facilitate its application it is generally most suitable to add a thickener such as the thickeners disclosed below for methylethylketone, ethylene dichloride and NaOH solutions. Thickeners for organic and agneous liquids are generally well known in the art and any may be used which are suitable. Examples of well known thickeners include pyrolytic silica such as that sold under the trademark "Cabosil" by Cabot, bentonite clays, derivatives of hydroxy ethyl cellulose, carboxy methyl cellulose and soaps or metal salts of fatty acids.
A resist (resist coat or resist layer) is normally removed after applying the etchant and prior to applying the replicating layer. However, as previously mentioned, the resist may be allowed to remain in place if its adhesion to the carrier is suitable and other properties are suitable so that it is not transferred when heat and pressure are subsequently applied to transfer the transferable portion; it becomes part of the non-transferable portion and thus part of the carrier when applied.
In other embodiments the resist may be allowed to remain in place after application of the etchant and prior to application of the replicating coat but it may be formulated so that it releases from the carrier and adheres to the replicating layer so that it becomes part of the replicating layer. For example, any one of the replicating formulations of Examples 5 and 7 through 13 may be used as a resist on Mylar, if its resistance to the etchant is suitable, and if then the same formulation is used for the replicating layer, the resist and replicating layers become undistinguishably part of the same layer and the unetched portion of the carrier is in fact replicated by that portion of the ultimate replicating layer which was originally applied as the resist.
In yet another series of embodiments, such a resist may be used and etching may be accomplished by abrading with fine particles. The fine particles (which may be sand, corncob particles, pecan or other nut shells, sawdust or any of a wide variety of materials) are forcefully directed against the surface by air blast, water blast or centrifugal throwing means and suitably abrade both the resist and the portions of the carrier which aren't covered by the resist. When a replicating layer of the same material (or similar material) as the resist is applied the resist and replicating layers become a single layer of replicating material and the abraded surface of the resist to which the replicating layer adheres entirely vanishes in the interior of the ultimately provided replicating material. As a specific example, any of the replicating layers of examples 5 through 13 may be used as a resist on Mylar for this purpose; in each instance, after etching by abrasion, the same material used as resist may be applied as a replicating layer. The resist then becomes part of the replicating layer, replicates the unetched portion of the Mylar to which it was applied, and transfers during heat and pressure transfer along with all other transferable material. ##SPC1##
In Table II, the presence of an X in a column indicates that a coating or layer is present in the example heading the column, and the absence of an X indicates the absence of a corresponding layer. ##SPC2##
Examples 1 to 8 are suitable for providing two-color patterns, if the color coats are printed, which may be simulated wood-grain patterns, simulated leather patterns and the like.
Although the examples show the presence of a release coat in all instances, a release need not necessarily be used in every case as made clear in connection with the drawings. ##SPC3## ##SPC4## ##SPC5## ##SPC6## ##SPC7##
Further embodiments and variations will be apparent to those skilled in the art and are intended to be included within the scope of the invention.