US2481390A - Method of applying sodium silicate binder - Google Patents

Description

Patented Sept. 6, 1949 METHOD OF APPLYING SODIUM SILICATE BINDER John M. Campbell, Cleveland, Ohio, assignor to John M. Campbell and Philmore J. Haber as trustees No Drawing. Application May 15, 1945, Serial No. 593.963

4 Claims.

My invention relates to binding agents in general, and in particular to binders for insulatin materials.

An object of my invention is to provide a binder agent for materials having interstices therein which binder is evenly distributed throughout the mass.

Another object of my invention is to provide a binder agent for materials having interstices therein which binder can be mixed with the materials having interstices therein without packing the material and destroying the air pockets provided by the interstices.

Other objects and a fuller understanding of my invention may be had by referring to the following description and claims.

Granulated and fibrous insulating and acoustical sound-absorbing material, such for example, as expanded vermiculite, granulated cork, glass, wool, rocE wool and similar materials, are employe or ea resisting, insulating and soundabsorbing boards by binding the loose material together with a suitable binder and either extruding or molding into final shape and form. However, heretofore known binders and methods of binding the loose insulating materials together into final form have been limited very much to specific uses. For example, many materials are highly inflammable, although having very excellent sound-absorbing and heat-insulating properties. These materials are often used in house insulating even though they add nothing to the fire-proof qualities of the house.

play is a well known and extensively use binder. However, a material bound together by clay is usually too heavy to float in water, and when wetted by an excess of water will allow the material to disintegrate and become useless. Further, clay will calcine under high temperatures and allow the insulating material to check and crack, and under extreme temperatures, to entirely disintegrate.

Water glass is another well known binding agent. However, water glass in its natural form is relatively viscous and syrupy. when water glass is mixed with one of the insulating materials referred to, there is a great tendency for one portion of the insulating materials to become over saturated with the water glass, while at the same time another portion becomes under wetted. The result is that one portion of the finished insulating material is exceedingly dense and hard whereas another portion is exceedingly light and fragile. The dense and hard portion will be found to have a higher coemcient of heat conduction than the light material, and therefore will act as a weak point insofar as the insulating properties are concerned. Again, water glass when used insufficient quantities to serve as a binder will not normally produce aninsulating material resistant to deterioration by moisture. Further, none of the known binders used today will increase the ability of the insulating material to withstand the effects of high temperature. That is, the finished insulating material will deteriorate and char at approximately the same temperature as would the original material.

My improved method of binding insulating material provides an evenly distributed binding action throughout the entire mass of the insulating material to bind the materials into a finished product of even density throughout, thereby preventing the described spotty condition of high density and low density areas. Further my improved method binder doesn't permit the insulating materials to calcine readily under relatively high temperature, and therefore holds the insulating material together under fire and intense heat. My binder also is so extremely light, that the density of the original insulating material will not be materially affected and therefore, the insulating materials may be flufied to include enough air space to provide a finished product with a density less than one. H

The basic conception of my invention is the neptizing rea n dh s xe. mater a 'i'rTiSi'dei'" unmw swe "swan 'dfl thejriatgi ial mightehe gsdueednn, aft erv the adhesive material isfntirely and thproughly mixed with the insulating materials to be bound. After being well mixed and distributed, the peptized adhesiy ma;

Serial No. 593,964, and filed concurrently here- I mat application, ex anded vermiculite g is impregnated with powdered aluminum Hydrate and magnesium carbonate. one examp e, e mpregna par c es are hen wetted with a solution of a slig1htl% acidic hardening ,geint. hereafter, a pep ize so u ion of an adhes ve material was slowly sprayed to the acidified mixtu'Tf'mhe mixture was being constantly stirred. Thus, the adhesive material is evenly distributed throughout the material because it is in an entirely fluid condition upon entering into the mass, whereafter it is precipitated as a j ell to completely enclose and supp'BY'FtliETrag'iIeWxpanded vermiculite particles. Aftegir ying, the adhesive material shrinks to a very small" amount of material, and therefore does not materially increase the weight of the insulating board. Although the jell is usually produced by preci itatin the adhesive material by an acid c mageflil, the principles involved include a prec pitation of certain binders by a reverse procedure, that is, a precipitation by chemical manipulation to change the pH value to the basic side. The use of this improved jell process of distributing an adhesive agent is not limited, however, to use with vermiculite and similar insulating materials. For example, lass wool and even saw dust has been shown to resist the action of Heat to a considerably greater degree when bound into insulating board by my process, than with any other known process today.

In actual operation, my improved binder jell may be used advantageously with any material (having interstices therein. The binder a ent such as water glass, resin, silica resi'n, e't'c., may be peptized By any mown 't'izin a ent suc'fi'asfifa'" for example, and then be evenly dis' persed roughout the mass of insulating material. Thereafter, a sli htly acidic solution may be added to the moistened mass to precip tate the adhesive in the form of a jell throughout the material. on the'other hand, if the insulating material used in the type having the body thereof made of individual laminated exfoliated cells, such as vermiculite, the mass may be first moistoned witli't lieicidic material to prevent the peptized insulating material from running into the interstices of the individual cell. That is, after the material has been y etted withthe acidic, mixture the peptized adhesiv rial will jell --shortly'afterbeing added tothemass, and there fore will not penetrate into the small openings of the material." Further, the peptized binder will remain fluid until the pH value thereof is shifted to the acidic side. Therefore, once the acidic property of the acidic materials is neutralized in one spot, the peptized fluid binder will pass over and be precipitated in another spot. over concentration of binder is prevented in any one spot. Thus, in the case of materials of this kind such as vermiculite or ran lated cork, the adh s ra ..ma.. 1a l; iw t min? nfielde of the individual cell particles'faiida'n insulating material is thus produced having a large amount 1 of entrapped-{air pockets and an appreciably lighter specific gravity. Ihe a cidic solution v f added to ause the peptized adhesive material 0 1 lell, may preferably be in the form of a ardenin .aLat .wbi l .....%.M eaia. We he... w i c3230 rt i e j .or example? Thav'e found "t at ma nes urosilicate will serve to prel cipita e n er as a jell, and at the same time serve to harden the adhesive material to better withstand the actions of high tempera- Thus an crease the lubricating action of the resultant jelled mass in order that the mass may be extruded from an extruding machine into shape. It is well known that extruded insulating materials are considerably cheaper to manufacture than those formed by molding. In addition to the clay or talc as a plasticizer or lubricant to help in extruding water-proofin a ents to increase th resistance to water, color, fillers and other matefii'FfiiEFlQiddd to the mass either before the wetting action or after. These materials are entirely auxiliary to the basic conception of jell distribution of the adhesive agent, and may be varied within suitable limits for specific purposes.

After forming into suitable shapes, the material may be air dried or oven dried as desired. In either cas'e'ftfie materiaTwill befund to have shrunk only a, fraction of one per cent of its original volume and will not be checked or cracked. The finished product may be sawed or nailed and may be used as a fire-proof filler between two walls. The jelled mass, before drying, or after being rewetted, is also an excellent plaster material being held tenaciously in place by the evenly distributed adhesive.

Although I have described my invention with a certain degree of particularity, it is understood that the present disclosure has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention as hereinafter claimed.

I claim as my invention:

1. An improved method of applying adhesive sfigiu nfgflmtejinwato material having inters ces erein, said In hod comprising the steps ofpeptizing the said sodium silicate with urea to form a peptized solution within the said material to be bound with the peptized sodium silicate solution and thereafter precipitating the sodium silicate in jell form by shifting the pH value of the peptized sodium silicate solution, the pH value being shifted by the addition of a solution of sodium flurosilicate.

2. An improved method of applying sodium silicate binder to particles of material to be bound together, said method comprising the steps of mixing the particles with an acidic soluton in quantities suflicient to moisten the surfaces of the individual particles, separately preparing a binder of peptized aqueous dispersion of sodium silicate and urea, and thereafter mixing the binder with the filled particles while the filled particles are still moist with the acid solution, whereby the peptized dispersion is precipitated as an adhesive jell, and thereafter shaping into forms and drying.

v 3. An improved method of applying an adhesive of sodium silicate to material having interstices therein, said method comprising the steps'of peptizing an aqueous solution of the said adhesive with urea, mixing the sodium silicate and urea solution with the said material to be bound, and thereafter precipitating the adhesive jell form by shifting the pH value of the peptized adhesive to a more acid degree, the pH value being shifted onaco cate and urea solution.

JOHN M. CAMPBELL.

REFERENCES CITED The following references are of record in the flle of this patent:

UNITED STATES PATENTS Number Name Date Mark July 8, 1919 Wiliett May 8, 1923 Bechtner- Nov. 3, 1931 Jack, 3rd Aug. 8, 1933 Kliefoth Oct. 16, 1934 Byers Apr. 13, 1937 Ward Apr. 19, 1938 Ostenberg Feb. 4, 1941