US2308185A - Adhesive composition - Google Patents

Description

are in rather extensive use..

Patented Jan. 12, 1943 ADHESIVE COMPOSITION Wesley N. Lindsay, Brooklyn, N. Y., and Harold Charles Li'etz, San Francisco, Caliik, assignors to The Arabol Manufacturing Company, New York, N. Y., a corporation of New York No Drawing. Application August 23, 1940, Serial No. 353,892

3 Claims. (Cl. 106-157) This invention relates to adhesive compositions, and more particularly to improved adhesives of the class containing gel forming protein, commercially termed "iceproof glue.

The adhesive of the present invention is useful for attaching paper labels and the like to containers, characteristic in that immersion in cold water does not disturb the adhesion of the label. Generally speaking, the iceproof glue or adhesive is used to attach relatively water permeable members, such as paper labels or the like, to reusable containers such as bottles. The labeled container may be immersed in cold or iced liquid over fairly long periods, the label firmly remaining on the bottle, not being removable by ordinary handling. A further general characteristic of iceproof glue is that a label attached therewith may be readily removed from the container by washing with warm water, even without the use of a detergent.

Iceproof glues are well known in the art and They contain an animal glue or similar gel forming protein in water soluble form, in a concentration which would set to a firm gel in the absence of modify- I ing substances. They also contain a highly water soluble substance which may be termed a gel inhibitor or liquifying agent. The inhibitor or agent is one which does not react with protein or alter its chemical structure to render it incapable of gelation. Its function is to inhibit the gelation or lower the temperature at which gelation occurs. When the agent is removed from the protein solution it leaves it in such condition that gel formation thereupon occurs.

The action or operational mechanism of iceproof glue is as follows: The adhesive film between the label and container contains the soluble protein and liiquifying agent in combination,

as previously stated. The label becomes permeated with water upon immersion in cold water. The highly water soluble liquifying agent rapidly dissolves, and difl'uses through the label. The concentration of liquifying agent in the adhesive film thereupon becomes reduced, and gelation of the protein is no longer inhibited. A gel is formed which can only extremely slowly disperse or dissolve in water. properties to adhere the label effectively onto the container. The gel so formed may however be liquiiied by heat. Thus, washing the label at an elevated temperature readily efiects a complete and clean removal of the label from the container. 1

Iceproof glue generally contains other ingredients than those mentioned. Starch, dextrine, or other modified starch is generally included to increase the initial viscosity or tackiness of the glue, and otherwise improve its operation with labeling machinery, or the like. It also decreases stringiness in the glue. The starch may be added to the adhesive composition in its modified form. On the other hand, it may be added directly andmodified in the process of manufacturing the adhesive. Another ingredient is generally added to decrease the rate atwhich the dry glue film is permeated and swollen by known to those skilled in the art.

Among gel inhibitors or liquifying agents previously used or proposed for iceproof glues are calcium chloride, calcium nitrate, magnesium chloride, sodium chloride, sodium nitrate, urea and lactic acid. However, the prior liquifying agents rendered the iceproof glue either so hygroscopic as to present greatly retarded drying rates under high humidity; or, decreased its iceproofness by permitting the liquified protein to dissolve too rapidly and difiuse through the label.

In accordance with the present invention, the use of a water soluble thiocyanate is proposed as the liquifying agent for animal glue gels, and particularly for application in adhesive of the iceproof glue type. We have found that the use of water soluble thiocyanate overcomes the disadvantages of the prior liquifying agents. The ad- The-gel has sufiicient adhesive v hesive composition of the invention is neither too hygroscopic nor too stable in its liquification. The adhesive composition or iceproof glue of the invention contains a water soluble thio'cyanate as the liquifying agent, the other ingredients being similar to those of the prior art compositions. We have found that the composition of the invention may be readily adapted for, all commercial applications for such adhesives, re-

2 I maining stable under widely'varying conditio- By way of example. the positions are given:

The proportions of the ingredients may of course be considerably varied. The procedure of preparing the adhesive composition is similar to that heretofore practiced, and wellknown by those skilled in the art. Briefly, the animal glue is mixed with the water and allowed to stand for one hour without heating. The mixture is then raised to a temperature of about to C. to complete the dispersion of the glue and the 'liquifying agent, namely the thiocyanate, is added to the mixture at about this temperature. The starch which may have been previously moistened with a portion of the water component, is then added to the mixture at the elevated temperature. The mixture is then agitated and heated in a temperature of to C. and the remaining ingredients of-the composition areadded. The resultant adhesive is then strained, if necessary, and cooled. In an alternate procedure, the starch is added in a dry state providing the liquified glue mixture is cooled from its 55 to 60 C. temperature to about 45 C. to inhibit lumping.

Suitable commercial water soluble thiocyanates are those of ammonium, sodium and potassium, although others may be used. Practical proportions of the thiocyanate is in the range of 25 to 60 per cent of the dry weight of the glue. Other starches than the tapioca and sago starches illustrated, may be used; as may dextrines or modified followins typical .corn- Example I Pounds Animal glue (360 gm.) 120 Ammonium thiocyanate 50 Tapioca star h 120 Water 259 Phenol 1 Total -L 550 Example]! 1 Pounds Animal glue (360 gm.)- 105 Sodium thiocyanate 52 Sago star h 105 Water 267 Lanolin 20 Phenol 1 Total 550 starches. The characterisation of the animal -mal glue, gel forming proteins, and gelatin may be used by suitably varying the formula of the composition to produce the desired results. The purified gelatin may be substituted. The protein used must have gel forming characteristics in aqueous solution which is inhibited or depressed by the liquifying agent.

Although specific compounds and compositions for practicing the invention have been described and illustrated, it is to be understood that modi-. flcations which fall within the broader spirit and scope of the invention may be practiced, and accordingly we do not intend to be limited except as set forth in the following claims.

What we claim is: I

1. An iceproof glue of the character described comprising the combination of a gel forming protein and starch in substantially equal proportions,

' and a water soluble thiocyanate in the proportion of about 60 per cent of the dry weight of said protein to inhibit gel formation of the protein in the composition, said thiocyanate dissolving out of the composition when it is immersed in water to effect gel formation of said protein therein.

2. An iceproof glue of the character described comprising the combination of a protein which disperses in hot water and gels upon cooling, starch substantially equal in amount to said protein, and a water soluble thiocyanate in the proportion substantially in the range of about 25 to cent of the dry weight of said protein for inhibiting the gel formation of the protein and gelatinizing and stabilizing dispersion of the starch in the glue. 4

WESLEY N; LINDSAY. HAROLD CHARLES LIETZ.