US 3562087 A
Description (OCR text may contain errors)
United States Patent 3,562,087 DECAL 0R TRANSFER LAYER ADHERED TO A CARRIER LAYER WITHOUT ADHESIVE John Percy Wigzell, Bulawayo, Rhodesia, assignor to Vactran Patents (Private) Limited, Bulawayo, Rhodesia, a corporation of Rhodesia No Drawing. Filed Dec. 7, 1965, Ser. No. 512,215 Claims priority, application/Rhodesia, Dec. 17, 1964, 469 6 Int. Cl. B321) 3/00 U.S. Cl. 161-127 7 Claims ABSTRACT OF THE DISCLOSURE This invention relates to transfers of the general type in which indicia are supported on a carrier sheet and are capable of being released therefrom to adhere to a receiving surface.
It is, of course, well-known to attach indicia to a carrier sheet by means of an adhesive and to secure their release by dissolving the adhesive in a liquid medium.
So called dry transfer materials are also known and they may require the application of heat or other means to separate the two elements.
The characteristic feature of known transfers is, however, the provision of an adhesive bond between the indicia and the carrier sheet which is brought into being either through the use of an independent adhesive layer or by using materials which naturally stick to one another.
The object of the present invention is to provide a transfer employing as indicia and carrier sheet respectively, materials which are not or are only lightly self-adherent one to the other and causing them to adhere firmly together by creating a pressure differential between the outer exposed faces of the two elements and the zone of contact between them.
In accordance with one aspect of the invention, there is provided a method of making a transfer comprising the step of applying an indicia to a carrier sheet so that a gastight rupturable zone of sub-atmospheric pressure is disposed between the abutting faces of the indicia and the carrier. In other words, the periphery of an area of the indicia sheet or layer is in direct contact with the carrier sheet so as to define a space which is gas tight, rupturable and also is at subatmospheric pressure.
The indicia and the carrier are thus retained in firm contact with one another by reason of the fact that the exposed outer faces of the two elements are subjected to atmospheric pressure, whereas the abuting faces are subjected to sub-atmospheric pressure, or a complete vacuum is created in the gas-tight zone.
To release the indicia from the carrier sheet, it is only necessary to rupture the enclosed space formed by the carrier and indicia layers, i.e., the gas-tight zone, as by puncturing the carrier sheet, whereupon the two pressures become equalised and little or no separating force is required.
The exposed face of the indicia will normally be coated with an adhesive, e.g. a contact adhesive of the non-drying type, by means of which it is caused to adhere to a receiving surface. Such adhesive will be covered in known manner with a protective layer which is stripped off immediately before the indicia is brought into contact with the surface to which it is to be applied.
To facilitate accurate location and registration of the indicia, it is preferred to use a carrier sheet which is transparent, or at least translucent. It has been found that a polyalkylene derivative, such as polyethylene or poly propylene, in flexible sheet form is a convenient material to use for this purpose. A sheet of at least 300 gauge is suitable.
The sub-atmospheric gas-tight zone may be obtained in one of several ways. In the case of solid indicia applied to the carrier sheet, air may be expelled from the relevant zone by forcing the indicia and carrier sheet together. For example, a pressure applying roller may be used or the required result may be derived by a stamping operation. In accordance with this method for obtaining the sub-atmospheric pressure zone the carrier sheet and/or the indicia must be sufiiciently resilient to enable opposed surfaces of the carrier sheet and indicia to close on one another, so expelling air, and subsequently to move apart under resilient deformation.
As an alternative to the solid mounted indicia the indicia may be applied to the carrier as liquids or pastes which exclude air as they are applied. When the wet state indicia set they adhere to the carrier through zones of reduced pressure which have been formed between themselves and the carrier. The fluids may be applied by roller, brush, or by means of a spray; with or without a stencil. Also a particularly effective method of applying the wet state indicia is by a silk screen printing process.
Oil and lacquer based paints and inks having sufficient flexibiilty when dry to withstand bending have been found to be satisfactory materials to apply to the flexible carrier sheet and they provide indicia which are durable and of a pleasing appearance. Enamel paint is particularly suitable. It is preferred that the thickness of these indicia should be about 0.0025".
Collodium geltine, egg white or pitch bitumen may also be used to form indicia.
Carrier sheets having a high gloss surface should be used with high gloss indicia; conversely, matt or semi-matt sheets should be used with indicia having a matt finish.
A preferred method for the formation of transfers according to the invention comprises the production of the desired indicia, for example lettering, in the usual manner with the aid of a Starlettograph machine on clear film. The images are transferred to a piece of Hi Fi Green Photographic stencil material which is then exposed to a quartz lamp in a vacuum frame. The stencil is then developed in A and B developer and stripped in the usual manner.
The stencil is then brought to a stainless steel mesh screen stretched on an aluminum frame. All open areas of the screen are blocked out to leave only the stencil area.
A millboard base board, first coated with lacquer-based silk screen ink on both sides to prvent absorbtion, is coated on one side with synthetic bees wax to retain a carrier sheet. The carrier sheet is cut from 500 gauge, heat drawn low density polyethylene, and is rolled onto the base board by means of a mangle type roller. This operation gives a degree of stretch to the polyethylene carrier sheet and ensures that it is evenly adhered to the base board.
Printing of the indicia is then commenced by lowering the screen into position over a base board with carrier sheet afiixed. The base board may conveniently be retained in position by a vacuum table. Enamel ink is then poured onto the upper surface of the screen and the ink is pressed through the stencil onto the carrier by means of a squeegee. The snap distance, which should be between one eighth and one quarter of an inch but which may be more or less depending on the particular circumstances, partly regulates the degree of reduced pressure that will be formed between the indicia material and the carrier sheet material. The pressure that is applied by the squeegee, through the screen to the carrier, accounts for the remainder of the reduced pressure effect.
When the carrier has been printed, it is racked in a dust free place for about 6 hours at about 75 Fahrenheit until properly dry. Once it is dry, it is overprinted with a contact adhesive through the same screen. Once this adhesive has settled, a silicone treated backing sheet is placed over the carrier and the carrier sheet is stripped from the base board. The base board may then be re-used for further operations.
It will be understood that the carrier sheet and the indicia must be non-porous to permit the formation of the gas-tight zone between them and, further, that the carrier sheet must not be soluble in, or otherwise deleteriously aifected by, the substance used for the indiciae.
If the indicia has been prefabricated in solid form, it may be applied to the carrier sheet by pressure which expels the air between the adjacent faces.
It will be appreciated that the adhesive used for securing the indicia to the surface upon which it is to be received may be of any desired strength. Thus, it is not necesary to use an exeptionally strong adhesive to overcome the adhesive force between the indicia and the carrier sheet as is required in certain known types of dry transfers.
1. A transfer sheet comprising an indicia layer and a carrier layer therefor;
both of said layers being adapted to substantially exclude air from entry between said layers;
both of said layers being in direct contact about the periphery of an area of said layers;
the said layers Within the said periphery being separated to form an enclosure which is gas tight, rupturable, and at subatmospheric pressure;
said indicia layer being adhered to said carrier layer substantially by means comprising said subatmospheric pressure and thereby, said indicia layer also being adapted to being removed from said carrier layer by rupture of said enclosure. 2. The sheet of claim 1 in which the exposed face of the indicia is coated -with an adhesive.
3. The sheet of claim 1 in which the carrier sheet is flexible.
4. The sheet of claim 1 in which the carrier sheet is transparent.
5. The sheet of claim 1 in which the carrier sheet is translucent.
6. The sheet of claim 1 in which the carrier sheet comprises a polyalkylene derivative.
7. The sheet of claim 1 in which the carrier sheet is polyethylene of at least 300' gauge.
References Cited UNITED STATES PATENTS 2,586,039 2/1952 Heggedal 40-125 3,013,917 12/1961 Karlan et al. 161-406 3,065,120 11/1962 Avelar 161-406 3,294,611 12/1966 Vomela 161-406 1,706,038 3/1928 Owens 101-128.4 2,156,680 5/1939 Dennison 156104X 2,397,827 4/1946 Williams 156230 2,408,147 9/1946 Kneale 156230 2,558,803 7/1951 Wittgren 156--240 2,591,779 4/1952 Buck 156230X 2,910,723 11/1959 Traver 204168 3,014,828 12/1961 Reese 156247X 3,212,913 10/1965 Mackenzie 156-230 FOREIGN PATENTS 589,276 12/1959 Canada 156--23O 393,132 6/1933 Great Britain, 1,293,384 4/1962 France 156-230 JOHN T. GOOLKASIAN, Primary Examiner W. E. HOAG, Assistant Examiner US. Cl. X.R.
ll7-3.l, 7; l56--230, 347, 253; l6140, 116, 146, 406.