USRE20326E - Adhesive and method of making same - Google Patents

Description

. Reissued Apr. 13, 1937 UNITED STATES PATENT OFFICE ADHESIVE AND METHOD OF MAKING SAME Edward F. Christopher, Chicago, Ill., assignor to Industrial Patents Corporation, Chicago, 11]., a corporation of Delaware No Drawing. Original him 1,962,763, dated June 12, 1934, Serial No. 649,233, December 28, 1932. ggigiifation for reissue June 1, 1936, Serial No.-

18 Claims. (c1. 134-23.9)

This invention relates to a new and improved will hydrolize, and give off objectionable ammonia composition of matter adapted for use as an adhesive, plastic massor coating material and suitable for numerous purposes and use in yasives made from casein and urea, that in those cases where it may be necessary or desirable, from the standpoint'of-commercial practice, to subject the adhesive to heat, or to boil the adhesive alone or with other substances, that the urea fumes. Also an adhesive of casein and urea is subject to attack by certain enzymes such as urease enzymes which contaminate the air and or biuret, cyanuric acid is also formed and perhaps a small quantity of ammonia. and in addition, some ammonia salt of cyanuric acid. The

invention therefore contemplates the use of these substances in combination because in practice rious industrial processes. This invention also produce by their attack, an undesirable decompo- 5 relates to a novel process by which a composition sition of the urea. 01' this invention maybe produced. Accordingly it is a further Object of this in- This compomtion of matter is characterized as vention to prepare an adhesive which possesses made from casein, and biuret and cyanuric acid. the advantages but is free from the objections It is an object of this invention to prepare an stated for urea, whereby it is neutral but will not 10 adhesive from casein which is neutral. give off ammonia fumes as above described and A further object is to prepares neutral casein will not be subject to attack by urease enzymes adhesive which may be utilized with or without 'with resulting decomposition of the urea cona hardening agent, such as an aldehyde, the use stituent.

of which will destroy the water solubility of the In furtherance of the above stated objects, it 15 adhesive and render it more durable and resistant is also an object of the present invention to proto deterioration and attack by bacteria and the vide casein adhesives which are transparent, free like. from odors, and adapted for various industrial It is a further object of this invention to prouses, particularly in connection with edible foodvide a casein adhesive which is water soluble and stufls, wherein it is highly important that the go which may be prepared initially in solution as a adhesive be free from. odors or any other inliquid or paste or if desired, in the form of a fluence that would contaminate or in any wise powder whichis sold dry and prepared for use, affect the food product. merely by the addition of water. These and other objects not specifically enu- It'has been well known prior to this invention 'merated are contemplated for this invention as that casein adhesives exhibit high adhesive propwill readily appear to one skilled in the art as m'ties. 'However, inasmuch as casein is insoluble the following description proceeds. in water and its use heretofore has involved the The present invention is based upon the disuse of alkalis, casein adhesives have been'uncovery that a clear neutral casein solution may suitable in many uses as substitutes for vegetable be readily produced by dissolving casein in an and animal glues; It is well known that alkalis aqueous solution of biuret, or more specifically, tend to discolor and in many cases, destroy paper, biuret, cyanuric acid, and perhaps also, ammonia and other objects to which the adhesive is apsalts of cyanuric acid. Furthermore, either ren-- plied. Furthermore, many of these prior art net casein or acid casein may be used in the prepcasein adhesives are subject to destructive action aration of this solution whereas heretofore, with a of bacteria when in solution, and the joints made alkaline solvents, only acid casein has beentherefrom are comparatively easily soluble inusable. Casein completely dissolves in a short water. time in the cold aqueous solution of biuret and As an improvement over the casein adhesives cyanuric acid and although variable quantities 4o utilizing alkaline solutions as dissolvirm mediums, of casein may be employed with success, casein 40 there is disclosed in Patent No. 1,725,805, Lanmay be'added in equal quantity by weight to the decker, issued August 27th, 1929, an adhesive prequantity of biuret and cyanuric acid employed. pared from casein and urea. This preparation is It is to be understood that this invention animprovement over the alkali solutions in that it contemplates the use of pure biuret as the disisneutral and further, in that it is subject to being solving agent for the casein but inasmuch as 45 hardened or rendered water insoluble by the acpure biuret is relatively expensive 'to obtain. it tion of an aldehyde so as to prevent the taking is intended that a mixture of biuret and cyanuric up of water such as might subject the casein to acid be employed. This mixture serves, admirthe destructive action of bacteria. ably in accomplishing the objects of this inven- The applicant has found however, with adhetion. It is well known that in the preparation acid and its ammonia salts and in its pure state with anequal degree of success.

Purely by way of example, this invention may be practiced by, first, preparing the dissolving re-agent for the casein by gradually heating dry urea until it reaches a temperature of approximately 160 degrees C. At 132 degrees C. the urea melts and at from 150 to 170 degrees C. it decomposes and gives oi! ammonia gas. After the urea hasmelted the product is agitated frequently while heating and the heating continued for several hours. The time required to raise the temperature to 160 degrees C. depends upon the amount of urea used and the source of heat employed. By way of illustration, when using approximately 1.5 pounds of urea and utilizing an oil bath, the time required to raise the temperature to 160 degrees C. is approximately two hours. Thereafter, heating of the urea is continued at between 150 to 1'70 degrees .C. for approximately two hours longer whereby the total heat treatment is conducted for about four hours. At this point air is blown through the melted mass to remove any ammonia which may be present. .The melted mixture so prepared which is known to contain biuret, cyanur'ic acid and ammonia or ammonia salts of cyanuric acid is then poured onto a slab or tray and allowed to cool and harden. The dry, hard product is then removed and ground to a powder in which iorm it is ready for use in preparing the casein solution.

The second step is the preparation of the casein solution. One preferred method involves the use of .100 parts by weight of casein (preferably '70 mesh) 100 parts of the dissolving re-agent prepared as above described, and 200 parts water.

The ingredients are first mixed and heated in a jacketed kettle or steam bath to a temperature approaching but not above 100 degrees C. until a smooth, viscous solution is obtained. The solution is then allowed to stand untfl cool and to permit the escape of air which is incorporated during the mixing. This periodwill vary according to the treatment employed but if al- .lowed to stand without special treatment. the mass will be cooled and freed of air in approxi- 50 mately sixteen hours.

It is tobe understood that the adhesive is in vthe nature of a colloidal suspension and accordingly the ingredients may be varied \through out'wide limits whereby the invention is not to be restricted to any exact proportions. In fact, it h found that with the dissolving re-agent here specifled,'only a relatively small amount of casein need be employed in order to give the adhesive 00 solution relatively high adhesive properties.

-'It is to be understood that the adhesive may be used for any and all commercial and industrial purposes but it may be mentioned that it has special usefulness in connection with the preparation of certain food products such as for instance, the gluing of normal cellophane in making artiiicial sausage casings or similar or analogous um.

Furthermore, according to the proportions em- 70 played in the concentration of the solution, an

adhesive can be obtained of any desired consistency, such as a relatively thin liquid or a paste of substantial viscosity. Furthermore, it is entirely practical to prepare the solid ingrei dientsintheiormofadrypowderwhichmay ao,sas

' they are found to give the desirable results here be sold on the market as such and thereafter prepared for use by the addition of the desired quantity of water. It is found that by the addition of water to the dry, powdered ingredients, that the casein is caused to readily dissolve to form the desired adhesive composition.

In addition, the adhesive of this invention may be treated for the purpose of altering its water solubility after its application or use, whereby the adhesive is rendered more stable and free from attack by bacteria or the like. This may be accomplished by reacting with an aldehyde which acts chemically therewith todestroy the water solubility of the adhesive.

The exact chemical reaction is not understood but it is known that the solubility of the product can be materially reduced in this way. This offers a substantial improvement over various prior, practices where various different methods were attempted which in most cases, would only penetrate the edges of the applied adhesive.

In the present invention, when the adhesive is in the form of a solution, a solution of formaldehyde may be employed or when the adhesivfe is prepared as a dry powder, a solid polymer of formaldehyde, such as para-formaldehyde, may

be added to the'solid mixture. The presence of formaldehyde in the mixture ofl'ers the advan tage of being thoroughly incorporated throughout theentire adhesive mass whereby its action upon the mixture in rendering it water insoluble is more completely and satisfactorily effected.

I claim:

1. An adhesive mixture comprising biuret, and water.

2. An adhesive, mixture comprising biuret, and aldehyde and water.

3. An adhesive mixture comprising biuret, formaldehyde and water.

4. An adhesive mixture comprising biuret, cyanurlc acid, and water.

5. An adhesive mixture comprising casein, biuret, cyanuric acid, an aldehyde, and water.

6. An adhesive mixture comprising casein, biuret, cyanuric acid, formaldehyde, and water.

'7. A new composition of matter comprising a powdered mixture of casein and biuret adapted to form a casein solution upon the addition of water.

8. A new composition of matter comprising a powdered mixture of casein, biuret and cyanuric acid adapted to form a casein solution upon the addition of water.

9. A new composition of matter comprising a powdered mixture of casein, biuret, and an aidehyde adapted to form a casein solution upon the addition of water.

10. A new composition of matter comprising a casein,

casein casein,

casein.

powdered mixture of casein, biuret, cyanuric' acid, and an aldehyde adapted to form a casein solution upon the addition of water.

11. A new composition of matter comprising a powdered mixture of casein. bluret. and formaldehyde adapted to form a casein solution upon the addition of water.

12. A new composition of matter comprising a powdered mixture of casein, biuret, cyanuric acid, and formaldehyde, adapted to form a casein solution upon the addition of water.

13, The process of preparing a neutral casein solution, which consists in dissolving biuret'in water. and then dissolving casein in the solution so prepared.

14. The process of preparing a neutral casein solution, which consists in dissolving bluret and cyanuric acid in water and then dissolving casein in the solution so prepared.

15. The process of preparing a neutral casein 5 solution, which consists in dissolving biuret in water, and then dissolving casein in the solution so prepared and finally hardening said adhesive by reacting with an aldehyde.

16. The process of preparing a neutral casein 10. solution, which consists in dissolving biuret in water, and then dissolving casein in the solution so prepared and finally hardening said adhesive by reacting with formaldehyde.

17. The process oi preparinc a neutral casein solution, which consists in dissolvinl biuret and cyanuric acid in water, and then dissolvin: casein in the solution so prepared and finally hardening said adhesive-by reacting with an aldehyde.

18. The process of preparing a neutral casein 7 solution, which consists in dissolving biuret and I cyanuric acid in water. and then dissoivin: casein in the solution so prepared and iinsiiy hardeninl said adhesive by reacting with formaldehyde.

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