FR2472588A1 - LATEX-BASED COMPOSITION, PROCESS FOR PRODUCING THE SAME AND APPLICATION THEREOF TO CONCRETE PREPARATION - Google Patents

Abstract

THE INVENTION IS ADDRESSED IN A GENERAL MANNER TO THE FIELD OF CONSTRUCTION. IT CONCERNS A LATEX COMPOSITION OF A RUBBER POLYMER CONTAINING IN PARTICULAR A DIOLEFIN CONJUGATED IN C A C, THE WAX PREFERABLY BEING A PARAFFINIC WAX DISSOLVED IN ONE OF THE MONOMERS. THE COMPOSITION OF THE INVENTION IS USEFUL IN PARTICULAR IN CEMENT MORTAR COMPOSITIONS FOR THE APPLICATION IN THIN LAYERS FOR EXAMPLE ON BRIDGE DECKS, OVERHEADWALKS, RAMPS, EXPRESS TRACKS AND OTHERS. LOCATIONS REQUIRING HIGH RESISTANCE TO PENETRATION BY WATER OR CORROSIVE LIQUIDS.

Description

Latex is a product well known for its plasticizing effects, adhesives

  and film-forming, either alone in coating or as an ingredient of a coating composition. When a latex is used as a component of a cement and a mortar, the concrete that is obtained after setting has one or more improved properties such as tensile strength, compressive strength, resistance bending and resistance to water, resulting in a more durable, watertight and wear resistant surface which may also be resistant to penetration by water and corrosive liquids such as only salt solutions. These latex modified cement and mortar compositions can be used for both new construction and restoration work. Pavement compositions containing a latex-modified Portland cement provide a concrete coating with improved tensile, compressive, flexural and adherent properties. It has also been found that a latex-modified concrete road surface is generally more resistant than conventional concrete to penetration by water and salt solutions and is

  generally less sensitive to the effects of freezing-

  defrosting and chemical etching even in layers

thin 1.90 cm or 2.5 cm.

  U.S. Patent No. 2,662,064 discloses a composition containing Portland cement, fibrous and non-fibrous fillers and pigments, a rubbery styrene-butadiene copolymer in the form of latex and a water-soluble thickener selected from class

  comprising hydroxyethylated starch, dextrin, hydroxypropyl

  ethylcellulose and sodium carboxymethylcellulose. This composition is intended to be used as a spray-applied surface wall decorative material having good adhesion and abrasion resistance properties. This patent does not mention whether the composition is endowed with the resistance to penetration by water or corrosive liquids which is desirable for example in the case of surfaces exposed to the action of freezing and thawing or to the effects of deterioration. chemical substances used for the removal of ice or snow, for example salt. U.S. Patent No. 3,892,704 discloses polymeric products of the type of a concrete which can be molded and which are considered to have

  very good properties of mechanical resistance and

  with a reduced tendency to develop an efflorescence. In this case, the polymer is formed by reacting a water-soluble ethenoid monomer, a water-soluble crosslinking monomer and an oxy-reduction catalyst system in the presence of a soluble alkali metal sulfate or carbonate. in water. The cement obtained as a product, containing the polymer, makes more rapid

  giving a concrete endowed with very good properties.

  Australian Patent No. 147,189 discloses a cement with a high alumina content, an inert filler and a vinyl polymer emulsion which make it possible to obtain a non-slip, good-impact, impact-resistant coating for

  metal, cement, wood or other substrates.

  U.S. Patent No. 2,979,476

  teaches mass polymerization of styrene in sight.

  to obtain a crystalline polystyrene containing a wax. The wax must be added when the monomeric styrene has reached a degree of conversion of 15 to 60% and the resulting product is a moldable composition to which it can be added.

  incorporate loads to obtain recording media

  very phonographic sensitive to sound, resistant to wear.

  U.S. Patent No. Reissue No. 28,722 discloses a cement mortar composition comprising Portland cement, a mineral aggregate, a styrene-butadiene copolymer latex, water, a nonionic surfactant, an anionic surfactant. and a surfactant consisting of a liquid polyorganosiloxane. This patent teaches that a lesser amount of water is needed to obtain a ready-to-apply cement mortar when the latex and

  surfactants are added. There are also improvements

  properties of the composition such as flexibility, adhesion, elongation of rupture and

of volume.

  U.S. Patent No. 4,039,345 discloses a shrinkage compensating Portland cement concrete and mortar composition comprising an expansive Portland cement, a mineral aggregate, a styrene-butadiene copolymer latex, water, a nonionic surfactant, an anionic surfactant, an anti-foam polyorganosiloxane and an anti-foaming armature. This patent discloses the very good properties of these compositions, such as the compressive and flexural strength and alternation resistance of the gel and the thaw. These compositions are particularly advantageous to use

  in the construction of structures without cracking.

  U.S. Patent No. 4,057,528 discloses a method for the repair of concrete, using cement mortar compositions capable of pneumatic spraying, which improve bonding capabilities and resistance to abrasion. drying. The cement mortar compositions comprise a Portland cement substantially free of

  of air, a mineral aggregate, a styrene copolymer latex,

  butadiene, water and a foamed polyorganosiloxane.

  None of the above-described prior art compositions involve the use of a latex which has the property of reducing the penetrability of the coating or composition in which it is used to improve the

  resistance to water and / or corrosive liquids.

  The Federal-Highway Administration has conducted research which is described in the report with the reference FHWA-RD-77-16 entitled "Internally

  Sealed Concrete: Material Characterization And Heat-

  Treating Studies. "This review reports on the use of small particles or spherical beads of wax mixed with the conventional components of Portland cement, concrete

  resulting in a wax content of about 3% by weight.

  After the concrete has set, heat is applied and the wax melts and flows into the capillaries and the exudation vessels of the concrete. The wax solidifies in

  these capillaries and interstices by giving a concrete shutter

  internally. However, it is assumed that the time and expense required to melt the wax throughout the concrete coating taken, the complex apparatus needed and the cost of energy to melt the wax

  make such a process difficult to achieve.

  It has now been found that a latex of a polymer containing the wax type additive, such as paraffin wax, prepared by dissolving the wax in one or more copolymerizable monomers which are then emulsion polymerized to form a latex of a polymer preferably containing rubber, is very advantageous for the preparation of a concrete containing this latex endowed with a very good resistance to water or to aggressive liquids such as aqueous solutions of salt. Latex

  can be incorporated with other ingredients into

  cement or mortar applications used for concrete products. Incorporation of from about 1 to about 20% wax by weight based on the total monomer content is effective to provide a latex supplemented with a sufficient amount of wax to achieve the desired water and liquid strength. aggressive. When such a rubbery latex containing a wax is mixed with a hydraulic cement mortar, the concrete obtained after setting has very good tensile, compressive and flexural strength properties as well as being able to very good properties of resistance to penetration by water or corrosive liquids, especially salt solutions, as shown by the low absorption of salt solution after prolonged exposure to this solution. The concrete produced with this wax-containing latex provides an improved road surface, especially in thin layers such as for deck decks, overhead passages, ramps, raised sections of expressways, and parking areas. multi-level car parks, etc., and withstands the detrimental effects of chemical substances used for the removal of snow and ice, thereby providing a durable and economical surface area.

  The present invention relates to a composition

  improved latex formulation, methods for producing the composition and improved concrete to which said latex has been incorporated, prior to setting, with the mortar or cement-forming materials used in the production of the improved concrete. A preferred embodiment of the invention resides in a latex of a rubbery polymer, especially rubbery polymers.

containing styrene-butadiene.

  The improved latex of the present invention is a latex of a polymer which contains a wax added with the particles of the polymer forming the latex. The latex polymer is a C4-C6 conjugated diolefin-containing polymer, preferably a C4-C6 conjugated diolefin-containing polymer and an aromatic vinyl monomer, and is most preferably a polymer.

  of a C4 to C6 conjugated diolefin, an aromatic monomer,

  vinylic acid and of one or more carboxylic acids

  ethylenic unsaturation or compounds derived therefrom.

  Representative examples of such polymers include polymers containing butadiene or isoprene, polymers containing butadiene or isoprene and styrene or α-methylstyrene, and polymers containing

  butadiene, styrene and one or more carboxylic acids

  ethylenically unsaturated compounds or compounds derived therefrom. Examples of suitable carboxylic acids include acrylic acid, methacrylic acid, cinnamic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid and atropic acid. Examples of suitable compounds derived from the acids mentioned above include acrylonitrile, acrylamide, methacrylamide, N-methylolacrylamide and C1-C6 alkyl esters of any of the acids.

  mentioned above. For such styrene polymers

  Butadiene, the weight ratio of butadiene to styrene is generally from about 70:30 to about 30:70. For polymers containing butadiene, styrene and ethylenically unsaturated carboxylic acids or compounds derived from these acids, the weight of butadiene is generally in the range of about 30 to about 70 parts by weight, the weight of styrene in the range of about 70 parts by weight and the weight of the acids or compounds derived therefrom is in the range of about 2 to about 10 parts by weight, for a total of 100 parts by weight. Suitable latexes of this type contain from about 30 to about 60, preferably about 45 to about

% by weight of polymer.

  The production of a latex by free radical emulsion polymerization is a well-known method in the prior art, which is described in the literature. A process for preparing a latex composition comprising a latex of a wax-added polymer according to the present invention comprises dissolving said wax in at least one of the monomers to be polymerized, and then subjecting it to emulsion polymerization. by free radicals this monomer or monomers containing the wax in solution as well as other monomers to be polymerized, in order to produce the latex of the polymer, the latter being a rubbery polymer containing a conjugated C 4 -C 6 diolefin, the amount of wax added from about 1 to about 20 parts by weight per 100 parts by weight of polymer. The process involves stirring at the desired temperature for the necessary period in the presence of surfactants or emulsifiers and other conventional additives such as

  chain transfer agents, initiators, activators

  etc. When the polymerization to the desired degree of monomer conversion is complete, the resulting latex is stripped of the residual monomers and the pH is adjusted to the alkaline value usually desired, for example by the addition of ammonium hydroxide. Any of the desired adjuvants such as stabilizing agents, antioxidants, deodorants, etc. may be added. A visual examination of the latex reveals that there is no free wax in this latex, which tends to prove that the wax was mixed with the polymer particles or incorporated into the particles of

polymer forming the latex.

  The waxes which can be incorporated into the improved latex polymer of the present invention can be chosen from natural waxes of vegetable or animal origin, mineral waxes and synthetic waxes. Representative examples of natural waxes of vegetable or animal origin include carnauba wax, candelilla wax, hydrogenated castor oil, uricury wax, Japanese wax, wax, wax, wax esparto, retamo wax, sugar cane wax, jojoba bean oil wax, palm wax, beeswax, spermaceti wax, Chinese entomocire, shellac wax and lanolin wax. Among these waxes, preference is given to carnauba, candelilla, bee and spermaceti waxes. Mineral waxes include peat wax, montane wax, ozokerite, and petroleum waxes such as paraffin waxes, microcrystalline waxes, and petrolatum. Among these waxes, preference is given to petroleum waxes, especially paraffin waxes and microcrystalline waxes. Waxes

  Synthetics include solid esters of polyhydric alcohols

  hydroxyl, for example glycerol stearates, high molecular weight (C18-C30) acids or alcohols and synthetic paraffin waxes as obtained by the Fischer-Tropsch process. It is for economic reasons that paraffin wax is used

  preferably in the present invention.

  It has been found very advantageous to incorporate the wax into the latex by dissolving it in a monomer before the beginning of the polymerization. When styrene is used as one of the monomers, it is preferable to dissolve the wax in monomeric styrene. The amount of wax contained in the latex is from about 1 to about 20, preferably from about 5 to about 15 parts by weight per 100 parts by weight of polymer in the latex. Since the monomers are generally not converted to 100% polymer, the amount of wax added to the monomer can be adjusted accordingly so that the latex polymer contains the desired amount.

  The incorporation of the latex wax by dissolu-

  In one of the monomers before the polymerization, it is obviously more efficient when the wax is dispersed throughout the mass of the latex polymer than if it is attempted.

  to incorporate a latex wax by mixing.

  The latex of the present invention may be mixed with the cement or mortars, together with the usually added aggregate and water, in a conventional manner. In accordance with general practice, Portland cement complying with ASTM C 150 for Type II non-airtight cement is mixed with sand in accordance with ASTM C 33 for concrete, in a normal cement mixer in a dry or semi-dry state for about 5 minutes. After this operation, water and the latex of the present invention are mixed and loaded into the mixer and the mixing operation is continued until a homogeneous mixture is obtained. We

  thus obtains an improved composition of concrete comprising

  Portland cement, aggregates, water, and a latex composition comprising a latex of a wax-added polymer, such that said concrete composition after curing has a high resistance to penetration by liquids. such as water or corrosive solutions of salt. It is presumed that the presence of wax is responsible at least in part for the very good quality of the concrete after setting. The invention therefore provides a process for preparing an improved concrete composition, which comprises mixing Portland cement, aggregates, water and a latex composition comprising a latex of a polymer supplemented with a wax and then let

concrete composition to make.

  The present invention can be illustrated by

the following example.

exmple

  Latex compositions A and B are prepared by mixing and emulsion polymerizing at a temperature of about 50 ° C the ingredients shown in the following table. All parts are by weight.

BOARD

  Styrene Butadiene N-methylolacrylamide Acrylonitrile Tertiododecyl mercaptan Paraffinic wax Water Dialkyl ester of the sodium salt of sulfosuccinic acid Dihexyl ester of the sodium salt of sulfosuccinic acid Colloidal mineral substance Tetrasodium salt of the acid ethylenediamine tetraacetic ammonium persulfate position A 4, 16 2.0 0.40 0.50 Composition B 4.16 2.0 0.40, 0 0.50 0.30 0.10 0.10 2, 0 0, 30 0.10 0.10 2.0 i. Paraffin wax is dissolved in styrene before

  to be added to the rest of the ingredients.

  After polymerization to a degree of trans-

  About 70% of the latexes are freed of the residual monomer and the pH is adjusted to a range of about 8 to about 10. The final

solids is 46.5%.

  15% of the latex composition A is added, based on the weight of dry solid latex relative to the cement, to a dry mixture of cement and sand using a ratio of sand cement of 1 to 3.25. Water is added in an amount sufficient to obtain a fluid mixture. After proper kneading, a 15.24 cm diameter and 2.54 cm thick concrete sample was prepared and allowed to cure after being covered with a wet wrapping cloth. After setting, the test piece is immersed in saline for 7 days and the saline absorption is measured by determining the weight of solution absorbed by the concrete. The absorbed percentage of salt solution is 15.7% by weight based on the weight after

  immersion compared to weight before immersion.

  The latex / wax composition B is mixed in the same way with cement, sand and water, the mixture is stirred correctly and an identical test tube of 24 cm in diameter and 2.54 cm in thickness is cast. and discarded after being covered with a wet wrapping cloth. After immersion for 7 days in a salt water solution, the amount of saline solution absorbed by the test piece is measured and the proportion of salt solution absorbed by the test piece is only 4.4%. Thus, the test piece containing wax absorbed only slightly more than 25% of the amount of salt solution absorbed by

  the sample does not contain wax.

  In contrast to the use of wax beads mixed with the concrete and then heated to split the wax, in the cured concrete, the present invention provides a much more economical and less expensive means.

  complex to achieve an advanced concrete coating.

he

Claims (9)

  An improved latex composition, characterized in that it comprises a latex of a polymer supplemented with a wax, said polymer being a rubbery polymer containing a conjugated C 4 -C 6 diolefin, the amount of wax added being between about 1 and about 20 parts by weight per 100 parts by weight of polymer. 2. Latex composition according to claim 1, characterized in that the polymer is a polymer containing a C4 to C6 conjugated diolefin and a vinyl aromatic monomer, preferably a polymer containing butadiene and styrene, with, in addition, the case optionally, one or more carboxylic acids with ethylenic unsaturation or   compounds derived therefrom.   3. Latex composition according to claim 2, characterized in that the added amount of wax, preferably a paraffin wax, is about 5 to about   parts by weight per 100 parts by weight of polymer.   4. latex composition according to claim 1, characterized in that the latex is mixed with Portland cement, aggregates and water * and in that it gives, at the outlet, an improved concrete endowed with a very good   resistance to penetration by liquids.   5. Process for producing a latex composition comprising a latex of a polymer added with a wax, characterized in that it consists in dissolving said wax in at least one of the monomers to be polymerized and then to be subjected to at a free radical emulsion polymerization the monomer (s) containing the solution wax and other monomers to be polymerized to produce the polymer latex, said polymer being a rubbery polymer containing a C4 to C6 conjugated diolefin, the amount added wax ranging from about 1 to about 20 parts by weight per 100 parts by weight of polymer.   6. Process according to claim 5, characterized   in that the polymer is a C 4 -C 6 conjugated diolefin-containing polymer and a vinyl aromatic monomer, preferably a butadiene-styrene-containing polymer, the wax being preferably dissolved in monomeric styrene prior to polymerization, with the optionally one or more unsaturated carboxylic acids   ethylene or compounds derived from these acids.   7. A process according to claim 6, characterized   in that the wax, preferably a paraffinic wax, is added in an amount of about 5 to about 15 parts   by weight per 100 parts by weight of polymer.   8. Advanced composition of concrete,   It comprises a mixture of Portland cement, aggregates, water and a latex composition containing a latex of a wax-added polymer, and in that it sets with high strength. to penetration by liquids.   9. Process for the preparation of an improved composition of concrete, characterized in that it consists in mixing Portland cement, aggregates, water and a latex composition containing a latex of a polymer containing a wax, then to have the concrete composition taken.