US1967688A - Treatment of glue - Google Patents

Description

Patented July 24, 1934 UNITED STATES PATENT OFFICE poration of New York to Haskelite Manufacturing Corporation, a cor- No Drawing. Application October 31, 1931, Serial No. 572,435

2 Claims.

The present invention has for one of its objects so to treat glue in a state of complete or partial desiccation that it shall become toxic and be able successfully to resist the attack of destructive bacteria, molds, fungi and vermin and become more water resistant and produce a stronger joint after it has set than is the case in the natural or untreated condition of the glue.

Another object of the present invention is to make it possible to simplify and improve the commercial practice of making joints with blood albumen glue, and to a lesser extent, caseinous glues, and avoid the considerable amount of waste that now results from the use of such glues.

In order to glue together two members with a blood albumen glue, it is necessary to press the members together with a layer of glue interposed between the same; heat being applied simultaneously with the pressure. Heretofore great skill and care has been required to insure that the glue is put in a proper state of dryness at the time the work is placed in the hot press, as it has been necessary to avoid either an excess or a deficiency of moisture in the glue. It has therefore been the practice to spread the glue on one or both of the faces to be joined, and permit the glue'to remain exposed to the air until it has attained the degree of dryness which experience has taught to be necessary in order to form satisfactory glue joints. Where much gluing is being done, this old practice means not only that there will be a lot of work lying about so that the glue can properly dry but, also, that occasionally high atmospheric humidity causes a longer than normal drying period to be required. This is very undesirable inasmuch as it leaves the pressing equipment and all its operators idle until the glue finally attains the proper state of dryness. Then,

40 again, whatever glue remains unused at the end of the day has heretofore been thrown away as it cannot be kept over until the next day. Consequently, there is a considerable loss because of wasted glue. By my invention I am able to overcome these objections and difficulties.

Blood albumen and other glues heretofore employed have been known to be subject to the attack of putrefactive and otherwise destructive 5 bacteria, molds, fungi, and vermin (insects). Especially was this true when the glue line was exposed to excessive moisture and humidity for any great length of time. In the process herein described, the resistance to destruction by bacteria, etc., is greatly increased; thereby effecting a greater longevity and durability of the glued product.

Although I have just referred to the ordinary commercial practice followed in joining veneers with blood albumen glue, my invention is not confined to that type of glue or to any particular method of introducing the glue between the surfaces to be united. In other words, glues of various types, as I shall hereinafter explain, may be in the form of layers, films or sheets, or any combination thereof, on one or both of the faces to be joined; or be separate therefrom and adapted to be placed between the same. In a broad sense, the glue may be wet, dry or'moistened after having been dried. In accordance with my invention, such a layer, film or sheet is coated with chemical reagents that will soften, plasticize, swell, condense, or coagulate or otherwise set the glue under pressure, with or without the application of heat, to form a strong, highly waterresistant, toxic binding material.

My present invention is applicable to many different kinds of adhesives among which are; blood albumen glue, with or without rubber latex whether in aqueous alkali dispersion or in organic solvent solution or emulsion; caseinous and caseinate glues; rubber latex or similar latices; socalled animal glues, made from the hides and other parts of animals; vegetable and leguminous glues as, for example, glues made from starches, soya beans, etc.; and phenol-formaldehyde resins or other natural or synthetic materials in a state of partially completed condensation, with or without having been combined with drying or nondrying oils of the fatty acid derivative type, or 90 with both of such oils.

The amount of the reagent that is applied to the layer, film or sheet that is being treated is ordinarily comparatively small. Usually the quantity of the active ingredients will be about 2 95 of the quantity of the glue that is being treated. The reagent may be applied in any suitable way as, for example, by spraying or by spreading it on with a brush or roller.

Generally speaking, if the reagent is intended solely to make possible the avoidance of waste in using glues having short working life, the reagent may consist of a material or materials tending to soften, and plasticize the glue to be treated; such material or materials being con- 1 5 tained in a suitable solvent or dispersing medium. Where the glue is to be made highly resistant to the attack of destructive bacteria, molds, fungi,

and vermin, the reagent must be composed of or contain a material or materials that will give a toxic character to the glue without weakening it.

In order that the glue treated thereby shall possess a high degree of water resistance, the reagent must consist of or contain a material or materials that are insolubilizers.

Ordinarily, it is of course desirable to employ reagents that will make it possible to secure all of the advantages of my invention and not only some of those advantages. Thus, I have obtained excellent results in avoiding waste of glue, facilitating the making of glue joints, securing the requisite toxicity, and insuring a high degree of water resistance, by employing a reagent mixture composed of:

a. I-Iydroxy compounds of aliphatic or aromatic hydrocarbons, or other suitable toxic materials,

acid or alkaline, which may or may not tend to condense, coagulate or otherwise render insoluble the glue to which it or they is or are applied;

2). Polyhydric alcohols (such as glycerine,) or other materials which tend to soften or plasticize the glue being treated, and at the same time (if necessary) act as solvents for the toxic or insolubilizing agents or both; 7

c. Water or other suitable medium or mediums for dispersing or dissolving, or both, with or without emulsifying agents such as fatty acids or derivatives thereof, alkali silicates, and rubber latex, which give the mixture bulk, and facilitate spreading in such concentration as is desired.

d. Halogen salts or esters, or other reagents, which tend to accentuate the toxicity of materials described herein, and which of themselves may or may not possess toxic properties.

A specific example of a reagent such as I have just described in general terms may consist of carbolic acid, glycerine, water and sodium chloride. The carbolic acid may comprise from 5% to 90% of the entire mixture; the glycerine from 0% to 25%; the water from 10% to 95% and the sodium chloride from 0% to 10%. It will be noted that in some cases there will be no glycerine and in some cases sodium chloride is not required.

The carbolic acid makes the glue toxic and causes it to coagulate or set. The glycerine is a solvent for the carbolic acid, gives body to the latter, improves the spreading qualities of the glue beingtreated and softens and plasticizes the glue. The water gives bulk to the mixture and makes it possible to spread a small amount of carbolic acid over a large surface. The sodium chloride increases the toxicity.

In some cases the reagent may consist simply of or contain compounds,- or mixtures thereof, alone or in solution known as aldehydes, conforming to the general formula CnH2nO, or which form aldehydic substances when reacted upon by other chemicals or heat. As examples may be given formaldehyde, acetaldehyde, etc., aldol, formates and acetates of alkali or alkali earth metals.

Such compounds or mixtures give the best results in connection with animal glues and may also be employed in the treatment of casein glues.

Again, the reagent may consist of or contain compounds, or mixtures thereof, containing sulphur in such form as to make the compounds useful in the vulcanization of rubber, or having setting or hardening or coagulating effect on latter has been spread or fashioned into a layer, film or sheet and is not mixed with the glue so as initially to form a part thereof. Ordinarily, if the reagent were mixed with the glue before spreading the latter, the glue would set so quickly, if a sufficient quantity of the reagent were employed to produce the advantages sought, that it would hardly be commercially feasible to employ such modified glues.

Quite aside from the advantages and savings that I have heretofore pointed out, my improved method results in a distinct saving due to e1im-' ination of much of the kiln drying to which glued veneer panels have heretofore been subjected.

In making panels of wood veneers joined together with blood glues, for example, it has heretofore been the practice to dry the veneers to a point where their moisture content is not more than about two percent. In the gluing operation so much moisture has heretofore been taken up from the glue by the veneer that long subsequent drying has been necessary to bring the completed panel to that state of dryness required in a commercial product. These two drying operations take considerable time, are costly, and often result in more or less checking of the exposed faces of the veneer.

When my process is employed, the glue may contain very much less moisture than heretofore, being in say an out of the dust state of dryness before the application of the reagent; the veneer need not be so dry initially; and, at the end of the gluing operation, the panel will contain less moisture than heretofore. The result is that there is a great saving in time and energy consumed in drying and, because the completed panel contains only a little more water than is desired, the final drying can be done without danger of checking the surface of the veneer.

The glue, as heretofore explained, may be applied in any desired way. Thus, it may be spread on one of two faces to be glued together and be allowed to dry before being treated with the reagent; the glue may be applied to both of the surfaces and be dried; or the glue may be applied to a sheet of paper or other fabric and dried, the reagent being then spread upon the glue and the sheet being interposed between the two surfaces to be joined together, which surfaces may be sized or unsized; or the glue may be placed in a dry, or comparatively dry, sheet form, wit out employing a holding or reenforcing sheet of paper or other fabric, and, after having been coated with the reagent, the sheet may be placed between the two surfaces to be joined.

After the members to be joined together have 1 been assembled with the treated glue arranged between the same, the subsequent operation may be the same as heretofore practiced in effecting the gluing, depending upon the nature of the glue. In some cases only pressure is required to complete the gluing operation whereas, in other cases heat, also, is necessary. 7

It should be understood that while I have named only a few specific reagents that may be employed successfully to carry out my invention, there are of course many other substances, materials or compounds whose characteristics are known to be such as to adapt them to carry out one or more phases of my invention. Furthermore, although I have heretofore stated that ordinarily it is impracticable to mix the reagents with the wet glues, before applying the glues, it will of course be understood that some of the substan es or materials may be mixed with the wet gIues. I therefore do not desire to be understood as limiting my invention to a treatment of glue by substances that in every case will secure all of the advantages of my invention, as long as there is some reagent that is applied to the glue while the latter is in layer, film or sheet form to afford the desired toxicity, insolubility or plasticity. It therefore follows that I do not I claim:

1. The method of uniting a wood member with another member which comprises spreading a wet blood albumen base adhesive over at least one of the two faces to be joined, drying the adhesive, moistening the adhesive with an aqueous solution of phenol, placing said members one upon the other with the adhesive between them, and applying pressure.

2. The process of gluing a wood member to another member, which comprises spreading a wet blood albumen base adhesive over one of the surfaces to be united, drying the adhesive, applying an aldehydic solution to the dry adhesive, assembling said members together, and applying p CHARLES E. ROZEMA.