US2782949A - Adhesives and method of applying to silicone-treated surfaces - Google Patents

Description

Unite ADIESIVES AND METHOD OF APPLYING TO SHICONE-TREATED SURFACES Lewis Marks, Jackson Heights, and Allison M. Stern, Mamaroneck, N. Y., assignors to Polymer Industries Inc., Astoria, N. Y., a corporation of Delaware No Drawing. Application January 11, 1954, SerialNo. 403,453

8 Claims. (Cl. 216-62) dated August30, 1955.

This invention relates to adhesives, and more particularly to the process of applying labels to containers, cloth, paper, or other surfaces which have been coated with silicones.

A new class of synthetic materials has appeared in recent years, known as the silicones or organosiloxanes. They have properties heretofore unknown in other materials and through adaptations have been utilized in a variety of desirable applications. Silicones have been employed by impregnating cloth therewith to render it water-repellent.

A further application of silicone has been to coat the inside of containers, bottles and the like, by dipping into or exposing them into the silicone. Among the advantages of using silicone as a surface coating are its resistance to adhesion, its chemical inertness, and its ease of application. While the aforesaid properties are most desirable, problems have arisen in labeling surfaces so treated. Further, in the forming of silicone coated paper bags and cartons, the resistance of the material to adhesion creates a problem in securing the flaps and tabs thereof.

Previous attempts to overcome the aforesaid difficulty have either proven unsatisfactory or not economically feasible. Solvents and wetting agents and even strong acids and alkalies have been employed without success. A partial success was achieved by using alkali 'alcoholates to wash the surface prior to any attempt at labeling, but the hazards and cost of this operation have made it undesirable. In addition, tl1e use of any of theforegoing methods would necessitate the redesign of existing labeling, boxing and bag machines. .A further undesirable feature of the prior methods is the reduction in the output of the machines caused .by the addition of another step to the process.

Accordingly, it is an object of this invention to provide an economical method of rendering silicone treated surfaces receptive of adherent materials.

An object of this invention is to provide a method of affixing labels to silicone treated surfaces without pretreatment with solvents, Wetting agents, chemicals or the like.

A further object is to provide a means of adhering labels to a silicone coated surface, so that a permanent bond is achieved.

A still further object of the present invention is to provide an adhesive composition capable of being used in the standard labeling, box making machinery, and the like.

With these and other objects in view, the invention consists of the improvements hereinafter described and claimed.

As will be seen from the subjoined description, the invention is based upon the discovery that acidic fluorides,

States Patent 2,782,949 Patented Feb. 26, 1957 even in very low concentrations, possess the property of destroying the resistance of a silicone-treated surface to adhesion.

Hydrogen fluoride, even when moderated and ameliorated by the presence of large quantities of viscous adhesive materials or thickening agents, have proven highly effective.

Other fluorides, such as ammonium bifluoride (ammonium acid fluoride), amine bifiuorides and sodium blfiuoride, are very effective in overcoming :the chemical inertness of the silicones and their adhesion resistance.

Alkaline fluorides have been found to be less active than those previously mentioned, but by adding acids to compositions containing alkaline fluorides, they may be rendered very efiicient.

Thus, it is within the purview of this invention to employ any suitable material or materials which either contain hydrogen fluoride or which can form hydrogen fluoride in situ, in compositions for the treatment of silicone-coated surfaces.

One of the many applications of the present invention lies in the formulation of adhesives. Adhesive bases suitable for use in connection with the compositions may comprise: starch and its derivatives, including ethers, esters, oxidation derivatives, torrefaction products, enzyme conversion products, wet and dry conversion products, dextrines, fluidity starches, and unconverted starches of all kinds, such as potato, rice, corn, wheat, tapioca, waxy maize, waxy sorghum, sweet potato, rye and sage; flours such as corn, wheat, rye and barley; proteins such as animal'glue, casein, wheat protein, soy protein, zein and gelatine and their derivatives; gums, suchas arabic, locust bean, tragacan-th and karaya, and their derivatives; a very wide variety of synthetic resins, including polyvinyl acetate, polyvinyl chloride, and their copolymers, polyamides, amide-formaldehydes, phenolic-formaldehydes, polystyrenes, polyacrylates and polymethacrylates, ethoxylines, alkyds, polyesters and polyethylenes; synthetic rubbers and natural rubbers of all kinds, and their derivatives; cellulose and its derivatives, such as ethers and esters; rosin and its derivatives and related products, such as the gasoline-insoluble fraction of pine-wood resin; sugars and their derivatives; asphalts and tarry materials; pitches derived from fatty oils; linseed oil, factices, and other oily materials; and other adhesive bases, able to unite one surface with another.

Compositions prepared in accordance with the present invention may be made to assume a wide variety of forms. Thus the composition has been successfully applied in the form of aqueous solutions, aqueous dispersions, solvent solutions, hot-melt compositions and catalyst or heatsetting resinous compositions.

Two specific examples of an adhesive composition made under the present concept, and which may be employed in a labeling, carton-forming, or paper bag making process, are as follows:

Example 1 347 parts (by weight) water 650 parts (by weight) soluble yellow tapioca dextrine 3 parts (by weight) phenol 500 parts (by weight) 60% aqueous solution of hydrogen fluoride, commercial grade Example 2 343 parts (by weight) water 644 parts (by weight) soluble yellow tapioca dextrine 3 parts (by weight) phenol 10 parts (by weight) 60% aqueous solution of hydrogen fluoride The mixtures in both the foregoing examples are prepared as follows: The water, dextrine and phenol are mixed and heated to near the boiling point. Stirring and 3 heating are continued until the dextrine is well dispersed. The mixture is then cooled to room temperature. The 60% aqueous solution of hydrogen fluoride, in the desired proportions depending upon which batch is being formulated, is then added to the viscous dextrine mixture.

The finished mixture, outlined in either of the two cited examples, can be applied to the label by means employed in labeling machines, prior to positioning it upon the silicone treated surface.

Another process, which can be employed in labeling, is to apply the adhesive composition to that area of the silicone surface which is to be covered by the label, then positioning thereon the dry label. A still further method is to apply the finished mixture in a thin film to the back of the label, to form the commonly known gum labels. The label may then be fed into a labeling machine, wherein it is moistened and positioned upon the silicone tneated surface.

In the manufacture of cartons the adhesive may be applied to the flaps of the blanks in a thin film. Thereafter, the flaps may be suitably moistened and the carton formed. Alternately, the flaps may be the adhesive applied thereto in the assembling process, in which case no moistening would be necessary.

In the making of silicone treated paper bags, the adhesive is applied to the surface just prior to forming, and by means well known in the art.

A third example of an adhesive, which may be employed in the above-described manner, is the following:

Example 3 375 parts (by weight) water 250 parts (by weight) animal hide glue (190 gram strength) 75 parts (by weight) thiourea 20 parts (by weight) phosphoric acid (75% aqueous) 80 parts (by weight) of a mixture of 1 part ammonium bi-fluoride; 2 parts of water, and 1 part of 28% aque ous armnonia Example 4 347 parts (by weight) water 650 parts (by weight) yellow soluble potato dextrine 3 parts (by weight) phenol 50 parts (by weight) sodium fluoride 40 parts (by weight) 75% aqueous phosphoric acid The water and dextrine are heated, as in Example 1; cooled to room temperature and the sodium fluoride then added with agitation. The phosphoric acid is added last.

Silicone coated aluminum foil may be made to adhere to paper by the use of a composition prepared in the following manner:

Example 5 Add to 100 parts (by weight) of water 50 parts (by weight) of 30% ammonia solution 50 parts (by weight) of ammonium bi-fluoride Eight parts of this mixture are added to 100 parts of a solution of polyvinyl alcohol, such as Elvanol 72- A-5l, manufactured by E. I, du Pont de Nemours.

Another specific example of an adhesive composition which can be utilized in securing labels to silicone coated cloth is the following:

Example 6 920 parts (by weight) of an emulsion of polyvinyl acetate in water (Ex. Du Po'nts 81-900) parts (by weight) dibutyl phthalate 30 parts (by weight) aqueous hydro-fluoric acid These materials may be mixed cold. This specific adhesive composition may be either applied to the label prior to being pressed upon the cloth, or may be applied directly to the cloth and the label thereafter placed upon the surface so treated.

It will be seen from the foregoing that several methods have been described whereby labels can be secured to silicone treated surfaces, or by which said surfaces may be secured together. In the methods disclosed herein there are present no dangers to the operators of labeling or bag and carton making machines, as the adhesives are free of strong acids or alkalies. In addition, while only a'few of the many adhesive compositions have been disclosed, it is obvious that many more types are possible, which can be employed to meet the variable factors encountered in the labeling process.

Further, it is apparent that the present labeling machine, carton and bag-making machines, need no modification in design or reduction in speed of operation, as the adhesive requires no special handling.

We claim:

1. The method of securing labels to silicone treated surfaces comprising the steps of mixing an acidic fluoride composition with an adhesive thickening agent compatible with said fluoride composition, applying said mixture to the'back of said label, positioning said label upon the silicone treated surface, and thereafter allowing the mixture to react with the silicone during the drying of said mixture upon the surface.

2. The method of securing labels to silicone treated surfaces comprising the steps of mixing an acidic fluoride composition of at least and not more than 35% by Weight with at least and not more than 99.9% of an adhesive thickening agent compatible with said fluoride composition, applying said mixture to the back of said label, positioning said label upon the silicone treated surface, and thereafter allowing the mixture to react with the silicone during the drying of said mixture upon the surface. 3. The method of securing labels to silicone treated surfaces comprising the steps of mixing an acidic fluoride composition with an adhesive thickening agent compatible with the said fluoride composition, spreading said mixture upon that portion of the silicone treated surface to be covered by a label, positioning a label upon the adhesive covered surface while said surface is still wet and thereafter allowing the mixture to react with the silicone during the drying of said mixture upon the surface.

4. The method of securing labels to silicone treated surfaces comprising the steps of mixing an acidic fluoride composition of at least with not more than 99.9% of an adhesive thickening agent compatible with the said fluoride composition, coating the back of a label and allowing said mixture to dry, moistening the back of said label and positioning said label under pressure upon the silicone treated surfaces and thereafter allowing the mixture to react with the silicone during the drying of said mixture upon the surface.

5. The method of forming and fastening a silicone treated carton blank into a carton comprising the steps of mixing an acidic fluoride composition with an adhesive thickening agent compatible with said fluoride composition, applying said mixture to the tabs of the said blank," folding said blank into a carton while said mixture is in a wet state, and thereafter allowng the mixture to react with the silicone during the drying of said mixture upon the surface.

6. The method of forming a silicone treated die-cut blank into a carton comprising the steps of mixing an acidic fluoride composition with an adhesive thickening agent compatible with said fluoride composition, covering the tabs with the said mixture, allowing the mixture to dry moistening the tabs, while folding said blank into a carton and thereafter allowing the mixture to re act upon the silicone during the drying of said mixture upon the surface.

7. The method of forming a silicone treated paper bag comprising the steps of mixing an acidic fluoride composition with an adhesive thickening agent compatible with said fluoride composition, applying said mixture to the tabs, allowing the acidic fluoride to etch the silicone surface and thereafter forming the said bag.

8. The method of securing labels to silicone treated surfaces, comprising, the steps of preparing a first mixture of 75 parts of thiourea with 375 parts of water, adding hide glue thereto and allowing said glue to soften, heating said first mixture to 140 F. for two hours, and thereafter cooling it to 120 F., preparing a second mixture of 1 part ammonium bi-fluoride, 2 parts of water and 1 part of a 28% aqueous ammonia, combining 80 parts of the said second mixture with the said first mixture, applying the composition thus formed to a label by positioning said label in intimate contact with the silicone treated surface and thereafter allowing the mixture to react with the silicone during the drying of said mixture upon the surface.

References Cited in the file of this patent UNITED STATES PATENTS 254,263 Bitterlin Feb. 28, 1882 1,470,772 Simon Oct. 16, 1923 1,471,466 Hogeman Oct. 23, 1923 1,980,179 Bergstein Nov. 13, 1934 1,988,265 Collings et al Jan. 15, 1935 2,118,386 Swinehart May 24, 1938 2,137,683 Flaherty Nov. 22, 1938 2,159,108 Staudt May 23, 1939 2,278,257 Gallagher h Mar. 31, 1942 2,493,984 McKay Jan. 10, 1950 2,716,612 Marks et al Aug. 30, 1955

Claims (1)

1. THE METHOD OF SECURING LABELS TO SILICONE TREATED SURFACES COMPRISING THE STEPS OF MIXING AN ACIDIC FLUORIDE COMPOSITION WITH AN ADHESIVE THICKENING AGENT COMPATIBLE WITH SAID FLUORIDE COMPOSITION, APPLYING SAID MIXTURE TO THE BACK OF SAID LABLE, POSITIONING SAID LABEL UPON THE SILICONE TREATED SURFACE, AND THEREAFTER ALLOWING THE MIXTURE TO REACT WITH THE SILICONE DURING THE DRYING OF SAID MIXTURE UPON THE SURFACE.