US 2700619 A
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United States Patent-O DECALCOMANIA PAPER James E. Sullivan, North Brookfield, and Harold 1. Kenneway, Jr., Brookfield, Mass., assignors to McLaurin- Jgnes Co., Brookfield, Mass., a corporation of Massac usetts No Drawing. Application October 9, 1951, Serial No. 250,576
5 Claims. (Ci. 117-'3.6)
This invention relates to decalcomania papers prepared especially for the printing thereon of decalcomania designs in such manner that they may be readily released for application to the surfaces of articles to which they are to be applied.
As is well known in the art, a decalcomania paper comprises a backing sheet carrying on its surface one or more coatings of a specially prepared adhesive which is dry and non-tacky under normal conditions, being adapted to take decalcomania printing, but which is activatable by water or other liquid to release the decalcomania when desired. There are a number of essential requirements for such a paper, first, and most important, the coating must be readily releasable (e. g. within 1 minute) from its backing sheet, and as a practical matter it must be releasable by water. Second, the decalcomania transferred coating must be transparent except in the areas of actual printing. This is particularly important in cases in which the decalcomania is to be applied to transparent materials, as if the coating is not transparent it will appear as a cloudy or dirty film surrounding the printed design and, in the case of face-down transfers, on the design itself. Third, the coating must adhere to the surfaces of a wide variety of materials in order that it may be of universal use.
In addition to the above essential requirements, we have found that there are a number of other practical requirements which should be met. For instance, it is, of course, desirable, particularly from a manufacturing standpoint, that but one coating rather than a number of coatings be used on the backing sheet, since a number of coatings, in addition to increasing manufacturing cost, greatly increase the manufacturing problems due, for instance, to possible incompatability of and interaction between the various coatings, as well as increasing the amount of cleaning of the transferred print.
Additionally, it is desirable from the standpoint of smoothness and uniformity of the decalcomania coating, to employ a smooth, hard finished backing sheet. Heretofore, however, it has been considered impractical to use such a backing sheet since such sheets were dense enough, because of the presence of the usual sizing therein, to prevent the essential rapid release of the decalcomania printed coating. Thus, unsized, highly water-permeable, and hence rough surfaced paper backing sheets have heretofore been standard.
Lastly, it is most desirable to have a decalcomania which readily can be released either by the slide ofi transfer method, in which the decalcomania printed coating is slid off the moistened backing sheet and applied with the back of said coating to the surface of an article, or by the face-down transfer method in which the decalcomania paper is applied with its coated face to the surface of an article and the moistened backing sheet then peeled off the decalcomania printed coating, leaving the coating on the surface of the article, since one or the other of said methods may be more desirable according to the type of design to be applied. For instance, it is almost impossible to use the slide off method with discontinuous designs since the various parts of the design cannot be readily kept in alignment, whereas it is relatively easy with the face-down method. On the other hand, continuous designs are somewhat easier and quicker to apply by the slide-01f method.
In accordance with the above requirements, then, we have devised a decalcomania paper providing the requisite releasability, transparency, andadhesiveness of the trans- 2,700,619 Patented Jan. 25, 1955 ferred coating, and one which is adapted to be used in either the slide-off or face-down transfer method of application of the decalcomania printed design. Surprisingly enough, we are able to produce our novel paper by a single water-activatable adhesive coating applied to a smooth-finished water-permeable backing paper sized with any of the usual sizing materials, for example rosin, waxes, starches, or glues, as Well as certain resins such as melamine, resulting in an improved printing surface as well as greatly reducing the cost thereof.
We have discovered that this novel result can be secured by employing dimethyl hydantoin formaldehyde as a constituent of the coating, such substance, together with its preparation, being disclosed in U. S. Patent No. 2,155,863. This material, in addition to being an excellent Wateractivated adhesive, provides an extremely high rate of release apparently by diffusion into the backing sheet when present in a significant amount with other wateract'ivatable adhesive materials, even when used on a sized backing sheet. For instance, we have found that, even using a highly sized backing sheet having a smooth surface, suitable releasability may be obtained when the dimethyl hydantoin formaldehyde is present in quantities as low as about 5% by weight of the dry coating, although with such low concentrations it is ocacsionally desirable to apply the usual starch coat to the backing sheet before applying the adhesive coat in order to increase the speed of release.
The water-activatable adhesive materials which may be employed with the dimethyl hydantoin formaldehyde to make up the remainder of the coating may be any of a number of well known watenactivatable adhesives or combinations thereof such as hide and bone glue, fish glue, gelatin, starches, modified starches such as starch acetate, dextrines, natural gums such as gum arabic, gum tragacanth, gum ghatti, cereal proteins as ortho protein from, say, wheat proteins, as well as various other natural and synthetic materials such as methyl cellulose, sodium carboxy methyl cellulose, polyvinyl alcohol, polyvinyl acetate, polyvinyl methyl ether, aryl alkyl polyether alcohol, sodium polyacrylate styrene butadiene copolymer, polyethylene glycol, etc.
Although dimethyl hydantoin formaldehyde is itself useful as the sole constituent of the coating, we have found that when it is present in amounts greater than, say, 70 or 80% of the dry coating, the resulting coating tends to become tacky under conditions of unusually high humidity. Hence, we prefer to use dimethyl hydantoin formaldehyde together with any of the water-activatable adhesive substances set forth above to produce a coating which will be non-tacky until activated under all atmospheric conditions, even conditions of unusually high humidity.
A formula which has proved particularly satisfactory for a face-down decalcomania paper is as follows, the constituents being given on a parts basis:
Dimethyl hydantoin formaldehyde 60 Aryl alkyl polyether alcohol 1 Polyvinyl alcohol 42 Polyvinyl methyl ether 1.6 Water In making up this formula the various components are mixed together and heated at temperatures of, say, to 'F. until they are thoroughly dissolved. The mixture is then cooled to approximately room temperature and then applied, as for example, in a coating machine of one or the common commercial types to a web of book raw stock having the usual amount of rosin size, such web having a smooth, dense surface characteristic of commercial sized paper. From the coating machine the web customarily is run through a drying chamber where it is dried in the usual manner in a current of hot air under time and temperature conditions such that the coating will not be broken down.
After the coating and drying operations have been completed, the web customarily is cut up into sheets of the size required for use by the decalcomania printers, such printing, in the case ofa face-down decalcomania, .being done directly on the coating made as. above described, or in the case of slide-off printing, if so desired, a lacquer coat can be applied over the coating and the decalcomania printing can then be done on this lacquer coat in a manner Well understood in this art.
We have also found that the releasability, particularly in the case of the slide-off transfer method, can be further improved by employing, in addition to the dimethyl hydantoin formaldehyde, a relatively small proportion of sodium cellulose sulfate, as such substance makes the coating extremely slippery when Wet with water and aids the sliding off of the decalcomania design. The significant quantities of sodium cellulose sulfate may range from as low as of the dry coating, although we prefer to employ about 20 to 25%. A suitable formula employing sodium cellulose sulfate is as follows, the constituents being given in a parts basis:
Dimethyl hydantoin formaldehyde .5 Sodium cellulose sulfate 6 Aryl alkyl polyether alcohol .3 Polyvinyl methyl ether .5 Water 7 The above formula is made up and applied in the same way as set forth above.
Other formulas as follows have been found useful, the percentage of dimethyl hydantoin formaldehyde in such formulas ranging fromas low as to as high as 92% of the coating mixture.
(l) Dimethyl hydantoin formaldehyde 5 Starch acetate 10 Water 25 Fish glue l0 (2) Dimethyl hydantoin formaldehyde 5 Hide glue 10 Water 15 (3) Gum arabic 4 Dimethyl hydantoin formaldehyde 6 Water 15 (4) Gelatin 6 Water 46 Ethyl alcohol 18 Dimethyl hydantoin formaldehyde 1O (5) Dextrine (corn) 7 Dimethyl hydantoin formaldehyde 5 Water l0 (6) Aryl alkyl polyether alcohol .2 Dimethyl hydantoin formaldehyde 8 Polyethylene glycol .5
(7) Urea .5 Aryl alkyl polyether alcohol .3 Polyvinyl methyl ether 1 Dimethyl hydantoin formaldehyde 6 Water 7 (8) Glycol stearate .2 Dimethyl hydantoin formaldehyde 10 Aryl alkyl polyether alcohol .1 Polyvinyl methyl ether .5 Water 7 (9) Clear Flow L starch (National Starch Prod.)
(sodium salt of starch acid ester containing carboxylic and sulphonic acid groups) Dimethyl hydantoin formaldehyde 10 Water 40 (l0) Ethylene diamine .2 Dimethyl hydantoin formaldehyde 5 Aryl alkyl polyether alcohol .1 Water 3 (ll) Dimethyl hydantoin formaldehyde 10 Special wheat protein (General Mills) 5 Water 10 (12) Dimethyl hydantoin formaldehyde 5 The dried adhesive coating is in each case composed of the same constituents referred to in the foregoing formula and in the same proportions, except for the water.
In applying the decalcomania print to the surface of an article either the slide-off or the face-down transfer methods may be employed. Ordinarily, the slideoff method consists simply in dipping the printed decalcomania sheet in water, removing it, and then, after allowing sufficient time for the print to become loosened by the water-activation of the adhesives, the decalcomania printing is slid off onto the surface to which it is to be applied. It retains a sufficient proportion of the adhesive coating to secure it firmly to the surface to which it is to be applied, and such application consists simply in pressing it against that surface.
In the face-down transfer method, the decalcomania sheet is similarly dipped and then the coating with the decalcomania print thereon is pressed firmly to the surface to which it is to be applied. After allowing sufficient time for the print to become loosened, the backing paper is carefully peeled from the design which remains on the article surface. The print remains firmly adhered to the surface, while the adhesive on the side of the print adjacent the backing sheet is largely removed by absorbtion into the backing sheet and by the water present since it is highly soluble, there being much less adhesive present than with heretofore known decalcomania papers having rough, highly absorbent backing sheets, since the backing sheet of our novel paper is smooth. Furthermore, our novel coating is clear and does not crack when dried; hence for many applications, even on transparent surfaces such as glass, it need not undergo any subsequent cleaning operation. Too, removal of excess adhesive after application of the print is much less of a problem than heretofore, since, after the decalcomania has dried, the final traces of adhesive may be removed by water if a particularly neat job is desired, although such is not necessary in most cases.
This invention has been found to meet all of the essential as well as the desirable requirements of a decalcomania paper, as set forth above, including those of providing a suitable surface to take the decalcomania printing, and freedom from handling difficulties during the printing operations. The adhesive coating thereof, when once dried, remains dry and non-tacky indefinitely without blocking under any and all normal atmospheric conditions.
l. A decalcomania paper adapted to carry decalcomania printing comprising a paper backing sheet and a uniformly smooth, dry, non-tacky, water-activatable adhesive, continuous coating united firmly to one side only of said sheet but readily releasable therefrom by water, said coating being composed mainly of a water-activatable adhesive material including at least 5% by weight of the dry coating of dimethyl hydantoin formaldehyde.
2. A decalcomania paper according to claim 1 in which said water-activatable adhesive material further includes 5 to 25% by weight of the dry coating of sodium cellulose sulfate.
3. A decalcomania paper adapted to carry decalcomania printing comprising a uniformly smooth, sized paper backing sheet and a uniformly smooth, dry, nontacky, water-activatable adhesive, continuous coating united firmly to one side only of said sheet but readily releasable therefrom by water, said coating being composed mainly of a water-activatable adhesive material including at least 5% by weight of the dry coating of dimethyl hydantoin formaldehyde.
4. A decalcomania' paper adapted to carry decalcomania printing comprising a uniformly smooth, sized paper backing sheet and a uniformly smooth, dry, nontacky, water-activatable adhesive, continuous coating united firmly to one side only of said sheet but readily releasable therefrom by water, said coating consisting of a singlelayer composed mainly of a water-activatable adhesive material including at least 5% by weight of the dry coating of dimethyl hydantoin formaldehyde.
5. A decalcomania paper comprising a paper backing sheet and a uniformly smooth, dry, non-tacky, wateractivatable adhesive, continuous coating united firmly to one side only of said sheet but readily releasable therefrom by water, said coating being composed mainly of a water-activatable adhesive material including at least 5% 5 by weight of the dry coating of dimethyl hydantoin form- 2,337,242 aldehyde and carrying decalcomania printing. 2,416,673
References Cited in the file of this patent UNITED STATES PATENTS 5 41,776 Hudson Mar. 1, 1864 564,424 2,089,779 Adair Aug. 10, 1937 6 Humphner Dec. 21, 1943 Asnes Mar. 4, 1947 FOREIGN PATENTS Great Britain Apr. 30, 1934 Great Britain Dec. 24, 1940 Great Britain Sept. 27, 1944