US2306570A - Process for protecting and coloring concrete - Google Patents

Description

Patented Dec. 29, 1942 PROCESS FOR PROTECTING AND COLOR- ING CONCRETE Edward W. Scripture, Jr., Shaker Heights, Ohio No Drawing. Application December 12, 1938, Serial No. 245,212

9 Claims,

This invention relates to the coloring of structures of concrete, mortar and artificial stone and has particular reference to floors, walks, roadways and the like from Portland or other hydraulic cement. The objects of the invention are the provision of simple and inexpensive means for imparting a uniform durable color to a hardened concrete structure of uncolored or natural cement colored concrete or mortar.

It is well known that to produce a colored concrete surface color should be introduced integrally in the concrete mix at the time the concrete is placed either in the form of a suitable pigment or of a colored aggregate or both.

Nevertheless the situation frequently arises that the coloring of the concrete has been neglected at the time of layingor placing for one reason or another, and it is desired to color the plain concrete subsequently. Hitherto no satisfactory solution to this problem has been offered.

There have been two methods of coloring plain concrete which have had fairly general application. These are painting and chemical staining.

Painting has never proved entirely satisfactory due chiefly to two causes, In contact with concrete in the presenceof even small amounts 'of moisture, painting is unsuccessful either because the paint itself is deteriorated by thealkali oi.

the cement or because the film blisters or peels;

Paint, furthermore, even if not attacked by moisture and alkali in the concrete, is not resistant to abrasion so that only short life can be expected under wear and frequent renewals are required. Chemical staining, usually with iron or copper salts, has been fairly satisfactory except for certain limitations. The available colors are limited to brown and green and intermediate shades derived from mixtures of these two. The

concrete to be stained must be in excellent con'- dition for successful application,"the results proa duced are entirely unpredictable, and it is impossible to secure an even or uniform color.

The coating and finishing of walls, blocks,

,bricks, floors, or other structures composed of,

.or smaller degree. Taking cement, concrete, or

lime mortar for example, the lime present (as well as other alkalies usually occurring together with the lime) attacks resin acids and fatty acids, as well as their glycerides (such as the linolein of linseed oil) forming lime soaps. On the one hand, this destroys the bond of the calcareous materials by the removal of lime, or the destruction of bonding compounds containing it,

and on the other, the formation of the lime soaps the idea of forming lime soaps, but this also affects the bond of the surface while the lime soaps do not prove in this case desirable components of the coating as theytend to oxidize and become friable and are hydrolytic. i

In any 'form' of concrete Ci -.ting containing acid material for the purpose of neutralizing the alkalinity ofconcrete, as is the case with certain.

types of concrete primers the speed of neutralization has to be considered. If the acid component acts rapidly, neutralization may be effected before the coating has set and dried. If the action of the acid component is slow, neutralization and reaction may go on after setting and drying of the composition, thus causing rupturing of the coating and its ultimate destruction. The resin acids differ from the fatty acidsin this respect. They are slower than the fatty acids in neutralizing activity, so slow in fact that under ordinary conditions a coating compound has opportunity to dry and harden before neutralizing reactions are fairly under way, and these reactions subsequently progress to the detriment of the coating.

The following brief comparisons may serve to explain the differences noted. The fats as glycerides form well characterized bodies. The resins are largely bodies resulting from condensation, are very fluctuating in composition and the nature of their compounds is not at all well established at the present time. The copals which are so extensively used in varnish making vary in composition very greatly. Manila copal, for

example, may have an acid number of 135,and a saponiflcation value of 185 while Angola copal will perhaps give an acid number of 60 and a saponification value of I35. Borneo copal will give an acid number of about 145 and a saponiflcation value of, say, 180. Amber contains about 30% resin acids and nearly 70% of saponifiable esters. Common rosin has an acid number of about 140 although this varies considerably with different grades. However, the uncertain composition of resins makes all these figures of indifferent value.

It will be apparent that neither the vegetable oils composed of fatty acid glycerides nor the natural resins containing as they do considerable proportions of saponifiable material are suitable for the purposes of my invention. Some attempts have been made to overcome this difficulty with natural resins by removing from the resin the saponifiable matter before incorporating it in the coating composition. Particularly this has been the case with resins separated from jelutong of different qualities known in the trade, according to the source from which they are derived, as palembang, pontianak, sarawak, and the like. Pontianak resin especially has been separated and treated for use as a coating material but the pontianak resin in and of itself, whether free of saponifiable matter or in its original condition, is not a very good coating material, being more or less friable and brittle.

The foregoing difficulties encountered in the use of drying oils and natural resins in coating compositions for cement surfaces may be overcome by the use of synthetic resins which form tough, impermeable and transparent films and which are themselves unsaponifiable and substantially immune to attack by alkali. Amon such resins are those formed by the treatment of rubber with hydrogen chloride, metal chlorides,

' or halogens, particularly chlorine, and known in the trade, for example, as Tornesit and Pliolite. Carleton Ellis in his book entitled The Chemistry of Synthetic Resins, volume II, published in 1935 by the Reinhold Publishing Co. of New cosity than those of the original material. They do not burn. Somewhat similar compounds are formed by the action of the hydrogen halides on rubber and related materials. Othersynthetic resins, such as the co-polymers of vinyl chloride and vinyl acetate, known as Vinylite, have similar properties and are suitable for the purpose of my invention. It is suflicient that the synthetic resin employed be chemically inert and unsaponifiable, that it be soluble ina suitable solvent to form a solution of low viscosity, and that it form a tough and relatively impermeable film.

Numerous methods of finishing concrete surfaces have been proposed. Painting has been used but as has been pointed out, paint on an alkaline surface is unsatisfactory. Many attempts have been made to overcome the difliculties due to the action; of alkali on paint. These have taken the form of treatments of the surface to neutralize the alkali or of applying a priming coat before the application of the paint. While the use of such materials as zinc sulphate, magnesium fluosilicate, or similar materials, to neutralize the alkali, have been to some extent beneficial the remedy is incomplete since York, on page 1117, footnote 83, states that chlorinated rubber'hasrbeen placed on the market under the tradekfame Tornesit.

On page 1102 of the above book, Ellis states that when 10% by weight of chlorostannic acid is milled into ,rubber and heated for two to five hours at 130 C. to 150 C., a tough balata-like material results. Long heating or excessive temperature forms a hard ebony-like substance. In footnote 132, Ellis states that these resins have been placed on the market by The Goodyear Tire & Rubber Company as molding materials and alkali-resistant coatings under the trade name Pliolite.

The reaction products of rubber and chlorostannic acid are described in Bruson Patent No. 1,797,188; this patent states that these reaction products contain combined chlorine.

The phrase chlorine-containing rubber derivative as used herein includes products as obtained by the treatment of rubber with chlorin'e-containing reagents, such as chloro stannic acid or chlorine, which are used in the preparation of Pliolite and Tornesit, respectively. The halogens react directly with rubber, guttapercha, or balata to form an interesting series of compounds possessing properties intermediate between those of rubber and the brittle natural resins. Highly chlorinated rubber, together with derivatives containing less chlorine, furnish a graduated series of products with elastic properties varying from that. of the original rubber to one of a tough leatherlike resin. The halogenated bodies are chemically inactive and are more soluble than the original stock in various solvents. The solutions possess much lower visonly the alkali on the surface is neutralized and subsequently alkali from the interior will penetrate to the surface. Priming coats such as treated oils, particularly Chinawood oil, various compositions of natural resins including the resins derived from jelutong, particularly pontianak resin, have been .more or less successful but usually fail in,one or more respects. Either the primer itself is not completely immune to attack by alkali, or it does not completely protect the overlying paint from attack, or the bond of the primer to the concrete surface is poor, or the bond between the primer and the paint is poor. In order to improve the bond, roughening of the surface has been employed, and this is of some benefit, but where the roughening is solely for the purpose of providing a bond for a surface film it is only a partial solution of the problem. Regardless of the methods used to prepare or treat the surface preparatory to painting. where the final finish is a paint coat it is always subject to wear. and gives only temporary resistance to abrasion.

In.addition to the use of chemical stains, that is solutions of compounds, usually of copper or iron, which react with the cement to form colored reaction products, it has been proposed to use dyes in solution in various organic solvents. While it is possible in this way to color a cement surface the dyes being transparent or translucent rather than opaque do not give complete hiding of the surface and do not produce a uniform, strong color. Furthermore, most dyes are more or less susceptible to fading in the light and the permanence of colors so produced is questionable.

It is an object of this invention to impart a pleasing uniform color to uncolored surfaces which will be resistant to moisture and alkali from the concrete and to abrasion from traflic or other wear, to provide a finish which will be resistant to most corrosives which are apt to come in contact with the surface, to provide a finish which is easily maintained and renewed if necessary and to secure these results by means of a reasonably simple and inexpensive treatment rocess.

In order to secure a colored finish which is durable and which will not be pushed from the surface by the action of moisture, alkali, or salt solutions in the concrete it is necessary thatsuitable colored pigment or pigments should be carried into the pores of the concrete and should be held there by a binding medium which is resistant to attack by moisture and alkali. It is further desirable that an alkali and moisture resistant substance should penetrate into the concrete and remain there to minimize the penetration of moisture to the surface. The color treatment should not, however, be such that a heavy coat, as of paint, should remain on the surface but rather the color should penetrate into the pores with only sufiicient on the surface to hide and color the surface. Finally to secure resistance to abrasion and provide easy maintenance the surface should be finished with a wax or waxlike substance which can be polished to form a wearing film which is preferably not'slippery. Thus, dependence is not placed on the pigment treatment for a wearing surface but only for a waterproofing treatment which will hold the color pigment firmly in place in the surface.

I have found that for pigments it is desirable to use finely divided alkali resistant pigments such as the inorganic oxides of iron, chromium,

manganese, etc., and also ultramarine blue. It is also desirable to use pigment dyestuffs such as the toluidine toners, Hansa Yellow, Monastrel Blue, etc.,. which are more brilliant in color, which are more finely divided and therefore will more readily enter into the pores of the concrete, and which are alkali resistant. To bind the pigments into the concrete surface I have found that solutions of alkali-resistant synthetic resins are quite effective. Synthetic resins of thetype of Vinylite may .be used; also synthetic rubber resins such as chlorinated rubber, cyclicized rubber and rubber hydrochloride. are very effective. As a penetrating, waterproofing substance I employ a resinous liquid which is of comparatively low viscosity but non-volatile and non-drying such as a chlorinated diphenyl, which is also nonsaponifiable. Owing to the saponifying action of alkali on drying oils such as tung and linseed oils, it is undesirable to use such oils in conjunction with this coloring process. While it may be possible to apply each of the'three substances described, pigment, synthetic resin, and penetrant separately with good results, it is preferable to incorporate the pigment and the penetrant in the resin solution so that all three may be applied in one operation. The proportion of pigment in the composition should be sufficient to fill the pores of the concrete and to just hide and color the surface of the concrete, but insufficient to increase substantially the viscosity of the composition or to cause the building up of a thick film like that of a paint on the surface of the concrete. The waterproofing penetrant should be present 'in sufficient proportion to give effective waterproofing and to help in carrying the pigment into the pores, but should not be present insuflicient quantity to impair the hardening of the synthetic resin. The resin in a suitable solvent should be present in sufficient quantity to bind'the pigment mineral spirits may be used in making solutions of these resins, an excess of mineral spirits tends to cause the formation of a more permeable film and this is particularly true where the mineral spirits used is of the same or lower volatility than follows:

Xylol c.c Rubber resin (Pliolite) g 10 Chlorinated diphenyl c.c 5 Oxide pigment g 4 Pigment dyestufi g 2 For the final finish coat I employ a wax or waxlike substance which is resistant to attack by moisture or alkali such as a high-melting point wax as canauba, or a waxlike substance such as a chlorinated naphthalene (Halowax). The latter has the desirable quality that it produces a wearing surface which is waxlike in that it may be-polished but is not slippery. .These waxes or waxlike materials may be applied either as solutions, either true or colloidal in suitable solvents, usually in the form of paste or as emulsions in water. I prefer their application as emulsions since this avoids the danger of softening the resin which holds thepigment during ap plication of the finish. Where a wax or waxlike substance with a melting point higher than the boiling point of water is used it is necessary to employ a small amount of a suitable solvent to lower the melting point of the wax or waxlike substance to permit thepreparation of an emulsion. To avoid the formation of streaks which are hard to polish out and to avoid the clouding of the color underneath by any whitening of the waxlike finish, it is often desirable to incorporate into the finish a small amount of pigment. An example of a suitable composition is as follows:

The process whereby the concrete surface is treated with these coloring and finishing compositions comprises preferably four steps. First, the concrete surface is thoroughly cleaned.- Second, the surface is etched with a dilute solution (10%) of a suitable acid (hydrochloric) in order to open the pores and allow penetration, the resultant salts are thoroughly washed from the surface and the surface allowed to dry. If the surface is already porous the acid etching may be omitted. I'hird, to the dry open surface is applied the composition comprising pigment, penetrant, and resin solution by scrubbing in with stiff brushes and brushing out with a soft brush to bring to an even surface. Fourth, when the pigmented treatment has dried the waxlike finish is brushed evenly over the surface, allowed to dry, and polished.

It will 'be seen that I have provided a process for treating concrete or cement structures whereby a'durable, wear-resistant-finish is obtained, which adds to the appearance of the structure and also protects its surface to a large extent from the action of the elements.

Many modification may be made of my invention without departing from the spirit thereof, and it is intended that it be limited only by the prior art and the scope of the appended claims.

What I claim is:

l. The'process of imparting a uniform, durable color to a hardened concrete or mortar structure, which comprises applying to the surface of such structure a liquid chlorinated diphenyl of relatively low viscosity, a coloring material, and a solution of at least one member of the group consisting of chlorine-containing rubber derivatives and chlorine-containing vinyl resins, and subsequently applying a coat of a high melting point wax-like substance.

2. The process of imparting a uniform, durable color to a hardened concrete or mortar structure, which comprises applying to the surface of the structure a solution of at least one member of the group consisting of chlorine-containing rubber derivatives and chlorine-containing vinyl resins, and containing a liquid chlorinated diphenyl of relatively low viscosity and an alkali fast coloring material, and applying a finishing coat of a high melting point alkali resistant, waxlike substance in aqueous dispersion, said coatings being further characterized by having no substantial amounts of drying oils.

3. The process of imparting a uniform, durable color to a hardened concrete or mortar structure. which comprises applying to the surface of the structure a solution of at least one member of the group consisting of chlorine-containing rubber derivatives and chlorine-containing vinyl resins, and containing liquid chlorinated diphenyl of relatively low viscosity and an alkali fast coloring material, and applying a finishing coat of a high melting point alkali resistant, wax-like substance in aqueous dispersion.

4. The process of imparting a uniform, durable color to a hardened concrete or mortar structure, which comprises applying to the surface of the structure a solution of a chlorine-containing rubber derivative and containing a liquid chlorinated diphenyl, a pigment and an alkali fast coloring material, and applying a finishing coat of a high melting point alkali resistant wax-like substance in aqueous dispersion, said coatings being further characterized by having no substantial amounts of drying oils.

5. The process of imparting a uniform, durable color to a hardened concrete or mortar structure, which comprises applying to the surface of the structure a solution containing chlorinated rubher, a liquid chlorinated diphenyl of relatively low viscosity and an alkali fast coloring material, and then applying a coat of an aqueous dispersion of a high melting point wax-like substance.

6. The process of imparting a uniform, durable color to a hardened concrete or mortar structure, which comprises applying to the surface of the structure a solution containing a chlorine-containing vinyl resin, a penetrating non-drying, liquid chlorinated diphenyl of relatively low viscosity, and an alkali fast coloring material, and then applying a coat of an aqueous dispersion of a high melting point wax-like substance.

7. The process of imparting a uniform, durable color to a hardened concrete or mortar structure,

which comprises applying to the surface of the structure a solution containing rubber hydrochloride, a liquid chlorinated diphenyl of rela tively low viscosity and an alkali fast coloring material, and then applying a coat of an aqueous dispersion of a high melting point wax-like substance.

8. In a process of imparting a uniform, durable color to a hardened concrete or mortar structure, the steps which comprise cleaning the surface of said structure, etching said surface with acid to increase its porosity, applying to said surface a solution of chlorine-containing rubber derivatives, said solution containing a liquid chlorinated diphenyl of relatively low viscosity and an alkali fast coloring material, and then applying a finishing coat of an aqueous dispersion of an alkali resistant wax-like substance.

9. The process of imparting a uniform durable color to a hardened concrete or mortar structure which comprises applying to the surface of such a structure a liquid chlorinated diphenyl of relatively low viscosity, a coloring material and a solution of a chlorine-containing rubber derivative and subsequently applying a coat of chlorinated naphthalene in aqueous dispersion.

1 EDWARD W. SCRIPTURE, JR.