US 3575788 A
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Arii 26, HQ?! .FUNK ETAL M. ADHESIVE COATED BEL WITH A L RELEASE COATING APPLIE TH T0 Filed April 18. 1968 United States Patent O US. Cl. 161-167 1 Claim ABSTRACT OF THE DISCLOSURE An adhesive coated label includes a coated paper construction having a paper base printed with labels message on one side and coated on the other side with an adhesive. A release coating on the printed surface prevents sticking of the adhesive to the printed side of the label and allows for gathering the label stock into rolls for convenient use. The method by which the label is made includes printing the label, applying a release agent in coated form, curing the release agent and thereafter applying an adhesive coating to the underside of the label.
BACKGROUND OF THE INVENTION Adhesive coated labels have been used for various purposes including the marking of price data on such packages as bread bags. For convenience in use these labels are gathered in roll form. Heretofore rolls of labels have required the use of an interleaving sheet to prevent the adhesive side of the label from sticking to the printed side. While this arrangement possesses certain advantages, it is nevertheless necessary to dispose of the interleaved sheet after using the labels. Moreover, the interleaved sheet adds to the cost of the overall label stock without the customer deriving a commensurate benefit from such added cost.
SUMMARY OF THE INVENTION The present invention contributes to the art of adhesive coated labels and provides a label which eliminates the need for interleaved sheets which prevent sticking of the adhesive side of the label to the printed side when the labels are in roll form.
In one embodiment of the present invention, a pressure sensitive label includes a base sheet of label stock printed with the usual message. The printed surface is overcoated with a layer of nitrocellulose lacquer and thereafter, such lacquer coating is covered with a coating of a release agent. The release agent preferably is a thermosetting silicone resin which provides for release and easy unwinding of the labels from roll form. Prior efforts to use silicone as a release agent have not been successful because the silicone transfers to and reduces the effectiveness of the adhesive side of the label when the labels are in roll form. The silicone acts as a release agent for the adhesive side with the undesirable consequence of preventing the label from sticking as intended to package or other product.
OBJECTS OF THE INVENTION Accordingly, it is the object of the present invention to provide a new and improved adhesive coated label and a new method of making the label.
Another object of the present invention is to provide a pressure sensitive label which eliminates the need for an interleaved sheet.
Another object of the present invention is to provide a pressure sensitive label having a release coating on the printed side thereof which does not transfer to the adhesive side of the label when the labels are in roll form.
3,575,788 Patented Apr. 20, 1971 "Ice Another object of the present invention is to provide a pressure sensitive label which may readily be handled by label applicating machines.
Other and further objects of the present invention will occur to one skilled in the art upon and understanding of the following illustrative embodiment of the invention, or upon the employment of the invention in practice.
DESCRIPTION OF THE DRAWINGS A preferred embodiment of the invention has been chosen for purposes of illustration and description and is shown in the accompanying drawings forming part of the specification wherein:
FIG. 1 is an enlarged section view of a label according to the present invention;
FIGS. 2 and 3 represent packages illustrating the manner in which the label according to the present invention may be used;
FIGS. 4 and 5 illustrate the method for making the label according to the present invention.
Referring more particularly to FIG. 1, the label 1 includes a base layer 2 of the usual paper stock which is printed at 3 with a suitable link to provide a message on the label. Preferably, the paper stock is approximately 40 to 60 lbs, per ream with the usual clay coating to make the paper receptive to the printed data on one side and t0 the adhesive on the other side.
The paper layer 2 is printed with a high heat resistant nitrocellulose base ink having a plasticizer content selected so as not to inhibit curing. The label is next overcoated with a layer 4 of high heat resistant nitrocellulose lacquer which prevents an unfavorable interaction between the release coating and the clay coated paper. That is to say the nitrocellulose lacquer acts as a barrier to prevent an outer release agent layer from contacting the clay coating. Such contact would inhibit the curing of the release agent.
Preferably, the paper layer is printed with the ink and the lacquer overcoating by using flexographic printing techniques.
As shown in FIG. 1, a release coating 5 is applied to the lacquer overlayer. The release coating prevents an adhesive layer 6 from sticking to the surface of the printed layer. The release coating is preferably a thermosetting silicone resin and is applied over the nitrocellulose lacquer coating 4. A suitable thermosetting silicone resin is a silicone rubber polymer (as for example Dow Cornings Syl-oif 23) dissolved in a suitable solvent like xylene or toluene to about 7 to 15% solids. In addition, an organic metallic catalyst (for example Dow Cornings Co Catalysts 23A, XY 139, or XY dissolved in a suitable solvent like toluene may be used as a catalyst in curing the thermosetting silicone resin.
The silicone resin coating is applied in a suitable manner as for example by a gravure cylinder 7 (FIG. 4) and is preferably applied in the amount of one-half pound of coating per ream of paper stock. After coating, the release coating is cured in an oven 8 at a temperature between 350 F. and 500 F. for about 4 to 6 seconds.
After curing, an adhesive coating 6 is applied to the underside of the paper layer. The adhesive coating is preferably pressure sensitive.
A suitable pressure sensitive adhesive may be produced by combining ingredients generally identified as a film former, a tackifying resin (or a combination of tackifying resins) and a plasticizer.
Preferably the film former belongs to the class of ethylene vinyl acetate copolymers. Such copolymers having an acetate content of from 14% to 40% and melt indices from 2.4 to 350 have been used in the present invention.
As to tackifying resins, either a single resin or a combination of resins may be used. If a single resin is used one liquid at room temperature is preferred. The tackifying resins are chosen from rosin derivations, terpenes, phenolic resins or hydrocarbon resins. Preferably the preferred tackifying resin includes a composition mixing a staybelite resin and a triethylene glycol ester of hydrogenated rosin.
Difierent plasticisers may be used in making the pressure sensitive formulation, including dibutyl tartrate, glycerol monoricinoleate, mineral oils, Santicizer HB-40, Plastolein 971 (polyester type), tricresyl phosphate, dibutyl phthalate, and Santicizer 8 (N-ethyl oand ptoluene sulfoamide).
Various changes have been made in the formula for the pressure sensitive adhesive and such changes have been examined in respect to the adhesive characteristics of the resultant product. The film former was varied from about 15% of the composition to 60% and the other ingredients were varied in relation to the film former. The plasticizer was varied from to 40% and the tackifying resin from to 70%. Adhesiveness resulted in these ranges.
FIGS. 4 and 5 illustrate the preferred method for making labels according to the present invention. As shown in FIG. 4, the paper layer 2 has been printed with a message and has been overprinted with the nitrocellulose lacquer coating 4. Next the layer 5 of thermosetting silicone resin is applied by means of a gravure cylinder 7 over the surface of the lacquer coating. Thereafter, the label web 1 is passed through a dryer 8 Where the silicone resin release coating is cured at a temperature of between 350 and 500 F. for about 5 seconds. After such curing the label Web 1 is coated on its other side with the pressure sensitive adhesive 6 which in cooperation with a smoother bar 9 provides a uniform tackiness over the surface of the web. A suitable roller 10 and glue supply 1 may be used to apply the adhesive coating. If desired, the label web may pass through a pan of cooling rollers 12 after the adhesive coating is applied.
In a final step, the web may be slit into individual Widths of label stock for shipment to a customer. FIGS. 2 and 3 illustrate packages 14, 15 which are using the label .as an end label 16 or as a price sticker 17 affixcd to the package (as in FIG. 4). In FIG. 5, the label stock may 4 be used as a header 18 aifixed in the nature of a fin or a header to the mouth of a plastic (usually polyethylene) bread bag.
It will be seen that applicant has provided a new pressure sensitive adhesive label, The advantages of thi new label are that it eliminates the need for an interleaved sheet and new label may readily be handled on label applicating equipment.
Various changes may be made to the form, constru tion, arrangement and composition without departing from the spirit and scope of the invention and without sacrificing its advantages and it is to be understood that the embodiments set forth are to be interpreted as illustrati've and not in a limiting sense.
What is claimed is:
1. A label comprising a clay coated paper sheet having a first surface and a second, opposite surface, the first surface being printed with a nitrocellulose base ink and overcoated with a nitrocellulose base lacquer, a heat-cured thermosetting silicone resin release coating applied over the nitrocellulose lacquer overcoating, the second surface being coated with a pressure-sensitive adhesive.
References Cited UNITED STATES PATENTS 2,133,914 10/1938 Burke 161406X 2,578,150 12/1951 Rathke l6l167X 2,588,367 3/1952 Dennett 117-122PS 2,768,460 10/1956 Northrup 16l167UX 2,860,083 11/1958 Nitzsche et a1. 117122PS 2,934,467 4/1960 Bergstein 161209 3,111,449 11/1963 Gold et a1. 16l406X 3,263,677 2/1966 Bradstreet 161-167X 3,328,482 6/1967 Northrup et al. 161406X 3,394,799 7/1968 Ritson et al 16l406X 3,432,333 3/1969 Hurst 161406X JOHN T. GOOLKASIAN, Primary :Examiner G. W. MOXON II, Assistant Examiner US. Cl. X.R.