CA1297219C - Alkaline curing emulsions for use in cement admixtures - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A cement admixture which results in a cement mortar with excellent adhesion to various adherents and with excellent flexibility over a wide range of temperatures, including very low temperatures, contains cement, optionally but preferably sand, and an effective amount of an aqueous emulsion of a cationic acrylate polymer having a Tg between below 10°C and -40°C. The polymer comprises (a) about 25 to 85% of an acrylate monomer (e.g., butyl acrylate, methylmethacrylate, or 2-ethylhexyl acrylate but not methyl or ethyl acrylate), (b) about 0.5-15% of the total polymer weight of an alkaline-curable cationic quaternary ammonium salt monomer, and optional monomer(s) other than (a) or (b). The alkaline-curable cationic quaternary ammonium salt units in the polymer are represented by the formula

Description

~Z97Z9L9 ~LKALINE C[~RING EMULSIONS FOR USE IN cE2~Nr ADMI~RES

BACK(~;ROUND OF THE INVhrNTION

This invention relates to cement admixtures containing an aqueous emulsion of an alkaline-curable polymer. The resulting cement mortars have excellent adhesion, flexibility, an~ waterproofin3 properties.
Aqueous emulsions of synthetic polymers have been added to cement admixtures which are used for the surface finishing of buildings or structures. The resulting cement mortars have shown improvements in adhesion, crack-resistance, impact-resistance, abrasion-resistance, flexibility, and waterproofing properties. The aqueous emulsions used have included synthetic rubber latex, acrylate emulsion, ethylene-vinyl acetate emulsion, and ethylene-vinyl chloride emulsion. Of these, the synthetic rubber latices are excellent in water~ and alkali-resistance, but unsatisfactory in ozone-resistance, heat resistance, and ~eather-resistance. Hence, they do not provide satisfactory cements. Ethylene-vinyl acetate emulsions provide good adhesion but are poor in water-resistance,alkali-resistance, and weather-resistan~e. Ethylene-vinyl ~, :

lZ97Z~9 chlorid~ emulsions have gocd adhesion and alkali-resistance, but are poor in heat-resistance and weather-resistance. Acrylate emulsions have a good balance of properties and have been widely used to provide the best cement admixtures.
Although acrylate emulsions have been used widely, attempts have been made to improve their performance, specifically to improve the adhesion of the cement mortar. One such attempt has been the introduction of carboxyl and epoxide groups into an ac~ylate polymer by polymerization with ethylenically unsaturated monomers containing such groups. Another attempt has been the introduction of a cationic charge into an acrylate polymer by polymerization with an ethylenically unsaturated cationic monomer such as alkylaminoethylmethacrylate. However, in some cases, the adhesion of the resulting oement mortar to certain adherents is still unsatisfactory, e.g., to adherents such as glazed ceramic tiles, plastic floor surfaees (epoxy resin, urethane resin, polyvinyl chloride, and the like), asphalt,concrete, steel, and plywood, as well as old and weathered concrete and mortar.
In order to increase the flexibility of the cement ~ortar, acrylate polymers havi~ a low Tg are added in large amounts~ The use of the low Tg polymers results in poor adhesion due to low cohesive strength. m ere is also a limitation on the amount of polymer e~ulsion which can be added to the cement. Hence, good adhesion and good flexibility have not been obtained simultaneously using the same polymer emulsion.

5 The present invention provides a c~ment admixture which results in a ~2~

cement mortar which h~s excellent adhesion to various adherents a~d ~hich maintains excellent Elexibility over a wide range of temperatures including very low temperatures. The cement admixture comprises a cement and an efEective amount of an ~queous emulsion of an acrylate polymer having a Tg below 1~ C to -40 C, which comprises a polymer o~ (a) about 25 to 9Y.57, of a hyd~olytically-stable acrylate monomer, (b) about 0.5-15~ by weight of the total polymer weight of an alkaline-curable cationic quaternary ammonium salt monomer, (c) 0-70~ of a hydrolytically-stable mono~er other than (a) or (b), and (d) 0-30~ of a hydrolytically-unstable monomer other than (a) or (b) with the percentages being by weight and totalling 100%;
the acrylate units in the polymer being represented by the formula --CH C--COO~ ~
and with the alkaline-curable cationic quaternary ammonium salt units in the polymer bein3 represented by the formula O=C R2 l +
A ~CH2)n I CH2 CIH I 2 where R is hydrogen or a methyl group; R is a Cl-C12 alkyl group or a C6-C12 cycloalkyl group with the proviso that R is not C1 or C2 when R is H; R2 and R3 may be the same or different and are a methyl or ethyl gro~p;
A is -O- or -NH-; X i5 chlorine, bromine, or iodine; Y is an organic or 7~

inorganic monovalent anion; and n is 2 or 3. The practitioner will recognize that the halohydrin gro~p (i.e., -CH-CH2J will be in epoxide O~i X
orm (i.e., ~ ~H2-) under alkaline conditions.
O
Aqueous emulsions of the above alkaline-curable cationic acrylate resins are effectively absorbed by the anionically charged cement particles. me cement and polymer particles are evenly distributed. The functional group (-CH-CH2) on the particle surface of the polymer are OH X
crosslinked in the presence of the alkalLne cement. When the cement is used as a mortar, it contains sand. When the cement is used as a paint, it may or may not contain a fine sand. The resulting oement mortar shows high adhesive strength even with difficult bonding surfaces. m e resulting cement paint shows improved flexibility and adhesion. Thus, it is possible to improve the low temperature flexibility without reducing the adhesive strength.
Typical alkyl or cycloalkyl acrylates or methacrylates include methyl methyacrylate, ethyl methacrylate, propyl acrylate or methacrylate, butyl acrylate or methacrylate, amyl acrylate or methacrylate, hexyl acrylate or methacrylate, 2-ethylhexyl acrylate or methacrylate, n-octyl acrylate or methacrylateJ decyl acrylate or methacrylate, lauryl acrylatR or methacry-late, and cyclohexyl acrylate or methacrylate. These can be used alone or in combination. If necessary, other monomers which can be copolymerized with the above-described monomers can be included. m ese incl~de hydroly--tically-s~able monomers such as styrene and its derivatives, acrylonitrile or methacrylonitrile, acrylic acid or methacrylic acid, vinyl pyridine, 2~

vinyl pyrrolidinone, alkyl amino acrylate or methacrylate, N,N'-dialkyl ac~ylamide or methacrylamide, dimethyla~inopropyl acrylamide or methac~ylamide in amoi~nts up to about 70~0 by weight. ~ydrolytically-unstable monomers such as methyl acrylate, ethyl acrylate, vinyl acetate, vi~yl chloride, and vinyl ethers may also ~e used in amounts which do not affect the hydroly~ic stability of the polymer, e.g., up to 30%
by weight. The term "hydrolytically-stable monomer", as used herein, means a monomer which does not hydrolyze at a pH a~ove 1~.
The preferred polymers contain about 40-60%, most preferably 50%
methylmethacrylate or styrene, 40-60%, most preferably 50%, butyl acrylate, 1-10% of the cationic monomer, and optionally 2-ethylhexyl acrylate, with t~e percentages totaling 100% and ~eing selected to give a polymer within the preferred Tg range of 0 to -10C.
The alkaline~curable cationic quaternary ammonium monomers useful herein are the adducts of an epihalohydrin and a dialkylaminoalkyl acrylamide or me~lacrylamide (where A is -NH-) or acrylate or methacrylate ~where A is -O-). These cationic halohydrin-con~aining monomers are described in U.S. Pat. No. 3,095,390 issued June 25, 1963 to A. Maeder 'which covers the methacrylamides) and UOS. Pat. No. 3,694,393 issued September 26, 1972 to S. N. Lewis (which covers the methacrylate).
Iypical adducts include adducts dimethylaminoethyl acrylate or methacryla~e, diethylaminoethyl acrylate or methacrylate, dimethylamino-propyl æ rylate or methacrylate, diethylamm oethyl acrylamide or methacrylamide, diethylaminopropyl acrylamideor methacrylamide~ and the like. The monomers are used in the salt fonm. Various salts are sui~able. Typical inorganic anions include chloride, bramide, sulfa~e and ,, ~ .. ... . . . ....... .. ..

~%~2~

nitrate. Typical organic anions include acetate, benzosulfonate and lauryl sulfonate. ~he preferred monomers are the chlorides or nitrates of dimethylaminoethyl methacrylate, dimethylarninopropyl methacrylate, and dimethylarninopropyl methacrylarnide. m ey are easy to manufacture or purchase and give acrylate polyners having good perfo~nance.
The amount of quaternary ammonium salt monomer ~sed i5 preferably 0.5-15~, preferably 1-10%, by weight of the total pol~ner.
Below 0.5~ the improvenent in adhesion and flexibility is insufficient and above 15%, the crosslinking density is too great, causing the polymer, and consequently the cement mortar, to become brittle.
The aqueous emulsions herein can be prepared by known polymerization methods, that is, by charging the above monomers with an initiator into a reactor with an agitator and a jacket or controlling the tem~erature and p~lymerizin~ at 50-80C and atmospheric pressure for 3-8 hrs. Conventional initiators and other polymerization additives such as surfactants and/or protective colloids may be used.
As the initiator, a peroxide or a combination of a peroxide and reducing agent typically is used. The preferred peroxides include:
potassium sulfate, ammonium persulfate, sodium persulfate, or hydrogen peroxide. me preferred reducing agents include sodium bisulfite, sodium hydrosulfite and ferrous salts (e.g.r ferrous sulfate/tartaric acid). The thiosulfate initiators are ~mployed in known catalytic amounts, preferably about 0.02-5% by weight based on the weight of the total monomers.
As surfactants, all conventional types can be used, hGwever, it is preferable to use a nonionic or cationic surfactant in order to provide the desired performanoe of the acrylate polymer. The preferred nonionic surfactants include polyoxyethylene alkyl ether, polyoxyethylene ~LZ~7Z~

alkyl~henol ether, and oxyethylene oxypropylene block copolymers. The preferred cationic surfactants include lauryl trimethyl ammonium chloride and alkylbenzyl dimethyl ammonium chloride. Although anionic surfactants are not as effective as the nonionic or cationic surfactants, they can be used. Suitable anionic surfactants are an alkali salt of a higher alcohol sulfate, alkali salt of alkylbenzene sulfonate, alkali salt of aIkylnaphthalene sulfonate, alkali salt of polyoxyethylene alkyl sulfate, or alkali salt of polyoxyethylene alkylphenyl sulfate.
As protective colloids, most of the known water soluble polymers can be used. m ese incl~de fully or partially hydrolyzed polyvinyl alcohol, an alkali salt of a fully or partially hydroly2ed sulfonated polyvinyl alcohol, cellulose derivatives such as methyl oe llulose and hydroxyethyl cellulose, polyethylene glycol, and polypropylene glycol. The amount of protective colloid i~ preferably 0.2~10~, ~ore preferably 2-5%, by weight based on the total weight of the monaners.
Buffering agents, preferably phosphoric acid, sodiwm bicarbonate, potassiun bicarbonate, sodium pyrophospha~e, potassiun pyrophosphate, sodium phosphate, and sodium acetate may be used. The amount used is preferably 0-5% by weight based on the total weight of the monomer(s).
The resulting polymers are dispersed in water ~hus fonmLng an emulsion. The preferred particle size is 0.1-1 micron. The polymer content (i.e., solids) in the emulsion is preferably 20-70~ by weight.
m e Tg of the acrylabe polymers is controlled by ~he carbon chain length of ~he alkyl group (i.eO~ R ) in the acryla~e or methacrylate monamer.
The polymer should have a theoretical Tg below 10C, preferably below O~C
and most preferably -10C or below. m e acrylate polymers become brittle ~ 9L297~9 when their Tg is over 10C and, consequently, the flexibility of the cement mortar is not improved. Ihus, it is necessary to keep the Tg below 10C.
Howeverf acrylate or methacrylate polymers having a Tg above 10~C can S ke used ir sufficient plasticiæer iS added so that the apparent Tg of the plasticized polymer composition is lowered to ~elow 10C. For the purposes herein, thes2 plasticized aqueous polymer emulsions are considered the equivalent of the non-plasticized polymer emulsions containing polymers ~a~ing the required Tg. The plasticizer can ~e added at the same time the raw materials are charged to the reactor or can be added after the po~ymerization reaction has ~een completed. The pre~erred plasticizers i~clude dibutyl phthalate, dioctyl phthalate, trLmethyl penta diol mono-iso-butyrate, trimethyl penta diol di-iso-butyrate, and butyl carbitol. The amount of plasticizer used is below 20% by weight, based an the total weight of the polymer. It is preferable to minimize the amount used.
With respect to the iower limit for the Tg of the polymers, if it is below -40C, the main chain of the the polymer becomes too soft and sufficient mechanical strength is not obtained even after ~he curLng has taken pl~ oe . ~ence, the preerred lower limit for the Tg is -40C, more preferably -30C.

The cement admixture herein is manuEactured by mixlng the aqueous polymer emulsion, cement, and~ if necessary, other a~ditives. All kno~n cements are suitable for use herein, i.e., Portland cement, rapid hardening cement, ultra rapid hardening cementt aluminum cement, jet cement, Portland blast furnace cement, Pozzolan cem~nt, sulfate resistant cement and white Portland cement. Fillers are used when necessary, and c, ., ~Z97Z~9 g the preferred fillers include silica sand, crushed sand, blast furnace slag sand, sea sand, Pe~lite, calcium carbonate, asbestos, al~ali-resistant glass fiber, steel fiber, carbon fiber, fly ash, titanium dioxide, and iron ore sand. The addition of a defoamer makes it possible to obtain high density cement mortars. The amount of defoamer used is preferably 0 5%, based on the aqueous emulsion. If a pigment is desired, iron oxide red and carbon black are preferred.
Typical cement mixing methods are suitable for mixing the above aqueous polymer emulsion and the cement. For example, the cement, emulsion, and necessary fillers (depending upon the end use) are mixed in a conventional mixer such as an electric mixer, a paint disperser, or a mortar mixer. In this case, the emulsion can be diluted previously with part or all of the water to be adde~ as mixing water for the cement. m e amount of polymer emulsion used should ~e sufficient to provide 1-200% of polymer solids based on the cement solids weig~t. The appropriate mixing ratio i5 selected within this range according t~ the use for the cement mortar composition. For example, when the adhesion i~ to be increased, 1-40%, preferably 5-25%, is appropriate. ~hen flexibility is to be provided, 25-200~, preferably 40-100%, i5 appropriate. E~ren though the mixing of the polymer emulsion and cement is carried out at room temperature, the curing reaction does not ~ake place immediately, but follows the rate of the cement hydration reaction.
In the typical cement mortar the ratio of cement to ~and to polymer solids is 1 to 0.5-4.0 to 0.05-0.25, whereas in the typical oement paint the ratio is 1 to 0-1 to 0.1-1. The resulting cement admixtures are suitable for use on various types of adherent surfaces, such as concrete structural walls, concre~e floors, waterproofing cement mortars, elastic ~2972~9 c~nent coatings, weathered ceramic tile surfaces, steel floors, or steel pipe surfaces. They are also suitable for joint sealing of concrete, autoclaved light weight concrete, and ceramic tile. They may be applied in the same manner as the usual Gement finishing methods, e.g., by the use of trowel, brush, or spray gun. m e amount applied will depend upon the use, typically a thick coating (1-50mm) is applied when the cement is used as a mortar and thin coating (1-2mm) is applied when the cement is used as a paint. m e curing of the cement admixture is carried out in air or in moist air.
When the cement admixture herein is coated on the adherent, the water in the cement admixture is decreased by hydration of the cement, by evaporation, and even by beiny absorbed into the adherent when the adherent has water absorbing capability. Upon loss of water the polymer particles, c~ment particles, and option~l fillers become more intimately in contact with each other. qhe acrylate polymers herein have many cationic groups on the surface of the acrylate polymer particles. me particles are more strongly cationically charged than those polymers containing added cationic surfactants or protective colloids, as well as those cationlc polymers containing no alkaline cur~ble groups (e.g., alkylaminoethylmethacrylate). m e particles, therefore, are absorbed and fuse~ more effectively with ~ anionir c~ment partid es an~ fillers.
The cemRnt admixture here m provides flexibilit~ and good adhesion which is not reduced by changes in temperature. Because the polymer has a Tg of below 10C it is rather soft, and the hardened cement shows ex oe llent flexibility, not only at ordinary temperatures, but also at low temperatures.

~29~2~

In the examples which follow, the parts are by weight, the Brabender viscosity is determined at 30C, and the réported ~9 values are theoretical (i.e., calculated) values rather than actual I~ values.

EXAMPLE I
S This example descri~es the preparation of an aqueous emulsion of an acrylate polymer (MMA/2-E~) containing an alkaline-curable cationic quaternary ammonium salt monomer. It compares the performance of a cement mortar containing this polymer emulsion with cement mor'cars containing aqueous emulsions of comparative acrylate resins.
. Par_A - Alkaline-Curable Acrylate Emulsion The following were charged to a 2 liter reactor equipped with an anchor-shaped agitator:

Initial Char~ Parts Polyoxyethylene nonylphenol. (20 moles EO~) 5 15 Sodium hydrogen phosphate 0.5 ~mmonium persulfabe 0.5 Hydroxyethyl cellulose (as a 2% solution having 3 a viscosity of 10 cps.) Water 100 20 * E0-ethylene oxide Total 109 Monomer Charge Parts Methyl methacrylate (MMA) 32 2-Ethylhexyl acrylate ~2-EHA) 65 25 Nitrate salt of DimethyIaminopropyl methacrylateJ 3.3 Epichlorohydrin adduct (DMAPMA/Epi ' ~O3) (90% soln.) ~00.3 ~2~72J ~

T~ initial aqueous solution Wa5 charged to the reactor, heated to 75C, and maintained at this temperature while the monomer charge was slowly added over 3 hours. After the slow addition was completed, heating was continued for 1 hr. The emulsion had a solids content of 51%, viscosity of 3500 cps., and pH of 2.2. The Tg of the polymer was -14C. Using this alkaline-curable cationic acrylate polymer emulsion, a cement mortar was formulated as follows:
Parts Portland cement 100 Standard sand 300 Acrylate emulsion 39.2 (20 as polymer solids) Defoamer ~VPCO NX~*
Water 45 It was poured into a 4.5 x 4.5 x 0.5 cm. frame placed on top of a 7.5 x 7.5 x 0.5 cm. glazed semi-porcelin tile and air cured for three weeks under standard conditions ~20C, 65~ relative humidity).

art B ~_Comparative Acrylate Emulsion~s An emulsion (B-l) of a commercially available cationic acrylate polymer, i.e., dimethylaminoethyl methacrylate/2-ethylhexyl acrylate/
methyl methacrylate ~DMAEMA/2-EHA/MM~), was used in place of the polymer emulsion of Part A. The amount used was sufficient to provide 20 parts by weight of polymer solids. The emulsion had a solids oontent of 40%, viscosity of 150 cps., and p~ of 5.4. The qg of the polymer was -5C.
An emulsion (B-2) of a commeroially available anionic acrylate polymer, i.e., acrylic acid/2~ethylhexyl acrylate/styrene (AAj2-EHA/St) was used in place of the polymer emulsion of Part A. It was used in an amount sufficient to provide 20 parts by weight of polymer solids. m e _ emulsion had a solids content of 58%~ viscosity of 700 cps., and pH of 8.
The Tg of the polymer was -20~C.

*Trade Mark ~72~9 The tensile butt adhesive strength of the three assemblies was measured using a Kenken type tester. ~ne results are shown in Table 1.
Table I

Polymer Adh~sive Breaking Behavior (~ failure) 5 Emulsion (Xg./cm. ) Stren~th InterfaceMortar or adherent Part A 6.8 0 100 Part 8-1* 3.1 90 10 Part B-2* 2.6 100 0 *Comparative The results show that the cement mortar containing tne alkaline curable quarternary am~onium salt monomer had excellent adhesion. The comparative acrylate polymers which had a Tg below 10C and one of which was cationic, showed much poorer adhesion. The results also show that the cement mortar containing the alkaline-curable monomer failed in cohesive strength (i.e., failed in the mortar or adherent) rather than at t`ne interface with the adherent, ~hereas the cement mortar containing the camparative acrylate polymers failed in adhesive strength (i.e., failed at the interface).
., EX~MPLE II
The polymerization was carried out as in Example I except that the initial charge was as shown below and the monomer charge was as indicated in Table II.
Initial Char~ Pa Polyoxyethylene octylphenol (15 moles EO) 5.0 Polyoxyethylene octylphenol (35 moles EO) 5.0 Potassium persulfate 0.5 Sodium hydrogen phosphate 1.0 Water 100 Total 111.5 *Trade Ma~k ~297%: L9 Table II

Properties of No. ~onom_r Composition (parts) _ Emulsion Pol~;mer DMAEMA/Epi. Add~ct Solids Visc, ~ Tg (90% Chloride soln.) MMA BA 2-EHA St (%) ~ (cps.) ( C) 2* 0 30 70 51.5 450 2.7 -11 3 0.55 29.5 70 51.4 430 2.5 -13 4 1.1 29.0 70 51.3 ~40 2.6 -14 3 3 27 0 70 50.9 ~60 2.7 -14 6 8 8 22 0 70 50.8 550 2.5 -15 7 11.0 20.0 70 50.6 300 2.7 ~16 8 15.6 16.0 70 50.6 290 2.6 -16 9 4 4 70 26 51.6 610 2.6 -12 10** 5 5 47 48 50.9 ~20 2.7 +13 1511** 5.5 5 90 5~.7 490 2.S -48 * Comparative - no alkaline-curable monomer **Comparative - outside Tg range The DMAEMA/Epi adduct i5 an adduct of dimethylaminoethyl m~thacrylate and epichlorohydrin.
~sing the resulting emulsions, cement mortars were formulated as follows:
Par~
Rapid hardening cement 100 Silica sand ~No. 6) 100 Silica sand (No. 7) 100 Silica sand (No. 8) . 100 Polymer emulsion 20 (polymer solids) Defoamer 0.5 Water 50 The mortars were poured onto four different adherents and cured for tw~
weeks under the standard conditions. The adherents and their dimensions were as follows:

SS41 Steel (6.0 X 9.0 X 0~9 cm) Plywood lauan (7.5 X 7.5 X 0.9 om) Semi-porcelain tile (7.5 X 7.5 X 0.5 om) Cement mortar brick (7.0 X 7.0 X 2.0 cm) qhe adhesive test results are shown in qable III. Ihe assemblies other than the plywood assembly were sub~ected to an aging test which involved the following cycles: submersion in water for 2 days at room temperature followed by drying for 2 days at 80C; after 5 such cycles the ~Z97Z~9 ass~mbly was cured for 1 week under standard con~itions. The sample designated No. 12 was obtained by modifyinq the polymer emulsion designated ~o. 10 with 5% of the plasticizer dibutyl phthalate to lower the apparent Tg of the emulsion from ~13 to 0C.
TABLE III

No. _ Steel Semi rcelain Cement mortarPl ~ ood Alr- After PO Air- After Air- After Cured Aain Cured A~inq Cured AgingCured a4ing 2* 5.7 8.3 4.1 1.2 5.~ 8.6 4.0 3 10.6 16.7 6.0 5.6 11.715.6 8.6 4 12.2 17.8 6.4 5.9 13.217.2 9.0 13.0 18.0 7.6 6.1 13.918.7 9.2 --6 14.1 19.2 7.2 5.8 15.220.6 9.5 7 13.2 19.0 8.0 6.0 14.918.6 8.0 --8 9.0 4.4 6.4 3.1 16.6 9.0 8.8 9 14.9 18.6 6.8 5.9 13.418.1 8.6 10** 16.8 8.0 7.8 2.4 19.2 9.3 8.8 11** 10.1 12.0 5.2 5.0 11.110.5 9.0 --12*** 14.4 13.9 7.0 6.0 18.217.2 8.1 * Comparative - no alkaline-curable monaner ** Comparative - outside Ig range ~**Same as No. 10 but modified with plasticizer m e results show that the cement a~nixtures containing ~he alkaline-curable cationic quaternary ammonium salt monomers had excellent adhesion to all adherents. m e comparative cement admixture ~see No. 2), in which a typical acrylate polymer emulsion i.e., an emulsion containiny a polymer with no alkaline-curable polymer, was used showed both poor initial adhesion and poor adhesion after aging. m e results also show that even when the ~lk2line-curable cationic quaternary ammonium salt nomer was used, if t~e Ig is abcve 10C (see Nb. 10), the adhesion after aging wzs unsatisfactory. When this p~lymer was used with the plasticizer, it was satisfactory (see No. 12). The results further show that an alkali-~2~729 ~

c~rable polymer with too low a Tg was inferior to the hi~her qg polymers (see No. 11). The appropriate Ig range for the polymer is thus demonstrated.
EX~MPLE Ill The polymerizations were carried out as in Example II using the monomers shown in Table IV.
~B~E IV
Monomer Composition No.
13 14* 15* 16* 17*
_ Nitrate Salt of Dimethyl-aminoethyl methacrylate/
Epichlorohydrin adduct (DMAEMA/Epi . N~3). 3.3 -- --(90% Nitrate soln.) Methyl methacrylate (MMA) 27 27 25 27 26 2-Ethylhexyl acrylate 70 70 70 70 70 (2-EHA) Other monomer** ~ 3 AA 5 GMA 3 DMAE~ 4 DMAPMhm .
_ Pro~erties of the emulslon and polymer Solids ~) 50.5 50.8 50.7 51.0 50.7 Viscosity (cps.) 300 810 240 280 250 pH 2.6 2.4 2.5 2.8 2.7 Tg tC) 23 -23 -25 -22 -24 * Comparative **AA is acrylic acid; GMA is glycidyl methacrylate; DMAE~ is dimethylaminoethyl acrylate: DMAPMAm is dimethylaminopropyl ~ethacryla~mide.
Using the résulting polymer emulsions, the following c~ment admixtures tdesignated A and B) were formulated:
(A) C~ment composition same as in Example II
Parts (B) ~hite Portland cement 100 Calcium Carbonate 50 Polymer emulsion100 (polymer solids) Methyl oellulose 0.2 Defoamer 3 Water appropriate amount ~Z972~g ~ e cernent admixt~res were thoroughly agitated and cement paints were made. Films (1 mm thick) were formed by immediately casting the paint on a Teflon*plastic plate. After curing for one month, the cement films were tested for tensile strength (m2ximum point) and elongation ( % at break) at -10, 20, and 50C using an Instron tester at a tensile speed of 200 mm/min.
The results are shown in Tables V and VI. The emulsion designated No. 18 was prepared using a cationic surfactant in place of the alkaline-curable cationic quaternary ammonium salt monomer and the polymerization was carried out using methyl methacrylate/2-ethylhexyl acrylate (35/65) as the monomers and lauryltrimethylammonium chloride as the surfactant. ~The polymerization was carried out as in Example I.
TABLE V - Adhesion ~k~/om2) of Cement A

' Polymer ~mulsion ~b.
.
herent Test Conditions13 14* 15* 16* 17* 18*

Steel Air-Cured 12.712.0 13.0 11.6 13.2 After ~ging 17.213.6 8.B 9.0 8.8 Semi porcelain Air-Cured 5.9 4.3 3.0 4.0 4.2 tile After ~ging 5.2 2.7 2.0 3.0 3.3 Cement mortar Air-Cured 12.6 11.4 12.2 14.2 13.2 After Aging 15.416.3 17.2 9~3 8.8 Plywood (Lauan) Air-Cured 7~7 5.4 5.6 5.0 4.3 -- -After Aging ~

I~BL~_VI Properties of Cement Film B

Emulsion No.
13 14* 15* 16* 17* 18*

Tensile strength (kg.~om.2) -10C 42.6 125 110 101 132 90.3 20C 12.6 15.213.6 9.0 10.6 5.0 30 50C 5.0 3.0 2.5 3.4 3.7 1.9 *Trade Mark ~297~

TABLE VI Properties of Cement Film B (cont'd) Emulsion No.
13 14* 15* 16* 17* 18*

~aximum elongation (~) -10C 220 40 30 105 90 105 50~C 1940 2~10 22002900 25002760 *Comparative The results show that the cement admixture containing the alkaline-curable cationic quaternary ammonium salt moncmer (No~ 13) was superior not only in adhesion to various adherents but also in the balance of tensile strength and elongation in comparison to the typical cement compounds (Nos. 14-18). Additionally, the variation in properties within the temperature range of -10C to +50C are slight, and accordingly the composition can be applied over a wide range of temperatures. m e typical cement admixtures showed a marked decrea æ in their perfonmance after aging, whereas the cement admixture herein (No. 13) maintained the initial adhesion level. It is believed this difference is due t~ the flexibility of this cement mort~r which allow~ for temperat~re variation. Typical cement mortars are not flexible.
~XaMPi~ VI
The polymerization was carried out as in Example I except that the reaction temperature was 70-75C and the slow addition time was 4 hours.
The charges are described below:
Initial Char~ Parts Polyoxyethylene nonylphenol (20 moles EO) 6.0 Ammonium persulfate 0.4 Sodium dihydrogen phosphate 0.5 Water 100 Total 106.9 `` ~Z97~

_ 19 _ Mon~ner Charge Parts ~thyl methacrylate (~ ) 10 Styrene (St) 15 2-Ethylhexyl acrylate ( 2-EHA ) 42 ~thyl acrylate (EA) 30 Nitrate salt of Dimethyaminopropyl methacrylamide/Epichlorohydrin 4.3 Adduct (70~ Nitrate Soln.
(DMAPMA~Epi. NO3) Total 101.3 The emulsion had a solids content of 50.2~, viscosity of 400 cps., and pH of 3.1. The polymer h~d a Tg of -14-C~
~ sing the above emulsion, a cement mortar was formulated as follows:

Rapid hardening cement 100 Silica sand (No. 7) 100 Silica sand (No. 8) 100 Silica sand (No. 9) 100 Resin emulsion 30 (as polymer solids) Oefoamer 2 Water Appropriate amount The flow value (detenmined according to ASTM C~30-55T) of the final cem;ent mortar was adjusted to 170 mm~ It was poured onto a 5 year old epoxy coated floor. It was smoothed to a thickness of 2-5 mm by troweling and cured or 1 week in air. lhe adhesion of the Gement mortar to the surface was 8.4 kg/cm2 after 7 day~ curing. Cements containing the comparative p~lymer em~sio~s B-1 and B-2 of Example I were also applied;
their adhesion was poor (both 0 kg/cm2).
EX~MPLE VII
The pol~merization was carried out as in Example I using the following:
Initial Charge Parts Polyoxyethylene nonyl~henol (25 moles EO) 7.0 Potassium persulfate 0.6 Water 70 Total 77.6 , ~2972~L~

Monomer Charge Parts B~tyl methacrylate (a~A) 15 Styrene (St) 10 Ethyl acrylate (EA) 25 Butyl acrylate (BA) 45 Chloride salt of DLmethylaminoethyl methacrylate /Epichlorohydrin adduct 5.5 (DMAEMA~Epi . Cl) (90~ soln.) Total 100.5 The emulsion had a solids content of 59.1~, viscosity of 1520 cps., and pH of 2.3. The polymer had a Tg of -18DC.
~sin~ the above polymer emulsion, the following cement mortar was formulated:

Rapid hardening cement 100 Silica sand (No.'7) 100 Polymer emulsion 50 (polymer solids) Defoamer 3 Water appropriate amount The flow value of the cement mortar wa~s adjuqted to 200 mm. The fresh cement mortar was patched on the h~llow places of asphalt mixed with concrete usi~ a trowel and the surfaoe was flattened. The cement mortar was cured for 1 week. A urethane coating for flooring was coated on the cement mortar with the thickness of the coating being S mm. ~fter 1 year, the constructed portion were examined thoroughly; no degradation was detected. Ihe adhesion to both the asphalt concrete resin an~ urethane resin was satisfactory. SLmilar evaluations were carried out with the comparative resins (B-1 an~ B-2 of Example I)~ me results were poor.
The cement mortar swelled due to the absorbtion of water from the under layer. lhe surface of the coated urethane becane uneven after 6 months.

~Z~7~

Example VIII (comparative) ~ nis example sho~ th3t the lower alXyl acrylates (C1 and C2) are poor in hydrolytic stability. A ethyl acrylate/2-ethylhexyl acrylate/dim-ethylaminopropyl methacrylamide/epichlorohydrin adduct as the chloride S salt (87.7/9.7/2.6) having a Tg of -28 was evaluated. A butyl acrylate/methyl methacrylate~acrylic acid (50/49/1) having a Tg of +2C
was also evaluated. The film weight minus loss (%) after immersion in alkali i5 shown belo~.
Polymer Days Inmersion ~ 5 12 19 33 ~7 EA/2-EHA4DMAPMA.EPI adduct In saturated cement solutlon* 1.1 1.7 1.8 2.3 2.5 2.8-In 5~ ~aOH solution 0.7 1.Ç 1.8 2.2 3.4 4.4 ~AA
In saturated cement solution* 0.6 1.1 1.5 2.0 2.2 2.2 In 5~ NaOH solution 0.2 1.1 1.5 2.0 2.2 2.2 *about pH 12 The resulks show that the butyl acrylate-based film sho~ed better alkali-stability.
Now that the preferred embodiments of the invention have been described in detail, various modifications and improvements thereon will become readily apparent to those skilled in the art. A~cordingly, the spirit and scope of the invention are to be limit~d only by the appended claims and not by the foregoing specification.

Claims (16)

1. A cement admixture comprising a cement and an effective amount of an aqueous emulsion of an acrylate polymer with a Tg between below 10°C and -40°C, the polymer comprising (a) about 25-99.5% of a hydrolytically-stable acrylate or methacrylate monomer, (b) about 0.5-15% by weight of the total polymer weight of an alkaline-curable cationic quaternary ammonium salt monomer, (c) 0-70% of a hydrolytically-stable monomer other than (a) or (b), and (d) 0-30% of a hydrolytically-unstable monomer other than (a) or (b) with the percentages being by weight and totalling 100%; wherein the acrylate unit in the polymer has the formula and the alkaline-curable cationic quarternary ammonium unit in the polymer has the formula Y- , where R is hydrogen or a methyl group; R1 is a C1-C12 alkyl group or a C6-C12 cycloalkyl group with the proviso that R1 is not a methyl or ethyl group when R is hydrogen; R2 and R3 are methyl or ethyl groups and R2 and R3 may be the same or different; A is -O- or -NH-; X is chlorine, bromine or iodine; Y- represents an organic or inorganic anion; and n is 2 or 3.

2. The cement admixture of Claim 1, wherein the acrylate polymer has a Tg with m the range of 0° to -30°C.

3. The cement admixture of Claim 1, wherein the acrylate polymer has a Tg within the range of 0° to -10°C.

4. The cement admixture of Claim 1, wherein the monomer of (a) is selected from the group consisting of methyl methacrylate, 2-ethylhexyl acrylate, and butyl acrylate.

5. The cement admixture of Claim 1, wherein the monomer of (b) is present in an amount of 1-10%.

6. The cement admixture of Claim 5, wherein the monomer is selected from the group consisting of the salts of a dimethylaminopropyl methacrylate adduct with an epihalohydrin, a dimethylaminoethyl methacrylate adduct with an epihalohydrin, and a dimethylaminopropyl methacrylamide adduct with an epihalohydrin.

7. The cement admixture of Claim 6, wherein the epihalohydrin is epichlorohydrin.

8. The cement admixture of Claim 6, wherein the salt is the nitrate or chloride salt.

-23-.

9. The cement admixture of Claim 5, wherein the monomer is the nitrate or chloride salt of the adduct of dimethylaminopropylmethacrylate and epichlorohydrin, or of dimethylaminoethyl methacrylate and epichlorohydrin, or of dimethylaminopropyl methacrylamide and epichlorohydrin.

10. The cement admixture of Claim 1, wherein the monomer of (c) is selected from the group consisting of styrene, acrylic acid, glycidyl methacrylate, dimethylaminoethyl acrylate, and dimethylaminopropyl methacrylamide.

11. The cement admixture of Claim 1, wherein the monomer of (d) is selected from the group consisting of methyl or ethyl acrylate.

12. The cement admixture of Claim 1, further comprising sand.

13. The cement admixture of Claim 12, wherein the amount of polymer solids present is about 1-40% based on the cement.

14. The cement admixture of Claim 12, wherein the amount of polymer solids present is about 25-200% based on the cement.

15. A method for improving the adhesion and flexibility of a cement admixture which comprises the step of adding to the cement an aqueous emulsion of an acrylate polymer with a Tg between below 10°C and -40°C, the polymer comprising (a) about 25-99.5% of a hydrolytically-stable the polymer comprising (a) about 25-99.5% of a hydrolytically-stable acrylate or methacrylate monomer, (b) about 0.5-15% by weight of the total polymer weight of an alkaline-curable cationic quaternary ammonium salt monomer, (c) 0-70% of a hydrolytically-stable monomer other than (a) or (b), and (d) 0-30%
of a hydrolytically-unstable monomer other than (a) or (b) with the percentages being by weight and totalling 100%; wherein the acrylate unit in the polymer and has the formula and the alkaline-curable cationic quaternary ammonium unit in the polymer has the formula Y- , where R is hydrogen or a methyl group; R1 is a C1-C12 alkyl group or a C6-C12 cycloalkyl group with the proviso that R1 is not a methyl or ethyl group when R is hydrogen; R2 and R3 are methyl or ethyl groups and R2 and R3 may be the same or different, A is -O- or -NH; X is chlorine, bromine or iodine; Y- represents an organic anion; and n is 2 or 3; the aqueous emulsion being added in an amount sufficient to provide about 1-200% by weight of polymer solids based on the cement solids.

16 The method of Claim 15, wherein the acrylate polymer has a Tg within the range of 0° to -30°C; wherein the monomer of (a) is selected from the group consisting of methyl methacrylate, 2-ethylhexyl acrylate, and butyl acrylate; wherein the monomer of (b) is present in an amount of 1-10% and is selected from the group consisting of the nitrate or chloride salt of a dimethylaminopropyl methacrylate adduct with epichlorohydrin, a dimethylaminoethyl metharylate adduct with epichlorohydrin, and a dimethylaminopropyl methacrylamide adduct with epichlorohydrin; wherein the monomer of (c) is selected from the group consisting of styrene, acrylic acid, glycidyl methacrylate, dimethylaminoethyl acrylate, and dimethylaminopropyl methacrylamide; the aqueous emulsion being added in an amount of about 5-25% when the cement admixture is to be used as a mortar or about 40-100% when the cement admixture is to be used as a paint.