Emulsion Polymer Two-Component Compositions For Fast Curing, Flexible Cementitious Waterproofing Membranes

Abstract

The present invention provides two-component compositions for making a waterproofing membrane comprising as component A) one or more acrylic aqueous emulsion copolymerization product (copolymer) of (i) from 60 to 89.9 wt. % of one or more nonionic (meth)acrylic monomers, preferably, butyl acrylate, methyl acrylate or ethylhexyl (meth)acrylate, (ii) from 10 to 40 wt. % of one or more vinyl aromatic monomers, (iii) from 0.1 to 2.0 wt. % of one or more amide functional acrylic monomer, and mixtures thereof with itaconic acid or methacrylic acid, wherein the emulsion copolymer has at least one residue of an ascorbic acid reducing agent and of t-butyl hydroperoxide and has less than 40 ppm or, preferably, less than 20 ppm, or more preferably, less than 10 ppm, of residual (meth)acrylamide.

Claims

1. A two-component composition for making a waterproofing membrane comprising as one component A) one or more aqueous emulsion copolymer having a residual (meth)acrylamide content of less than 40 ppm, and, as a separate component B), a fast curing dry mix powder composition of a hydraulic cement and a high alumina, content cement, wherein at least one of the one or more aqueous emulsion copolymers in component A) is the copolymerization product of (i) from 60 to 89.9 wt. % of one or more nonionic (meth)acrylic monomers, (ii) from 10 to 40 wt. % of one or more vinyl aromatic monomers, (iii) from 0.1 to 3 wt % of one or more monomers chosen from, amides of a,-unsaturated C.sub.3 to C.sub.6 carboxylic acids and mixtures thereof with itaconic acid or methacrylic acid, all wt. %s of monomers based on the total monomer solids used to make the aqueous emulsion copolymer, wherein the aqueous emulsion copolymer has a residue of an ascorbic acid reducing agent, preferably, isoascorbic acid, and a residue of t-butyl hydroperoxide, and, further wherein, the mole ratio of t-butyl hydroperoxide to ascorbic acid reducing agent in the aqueous emulsion copolymer ranges from 1.0:1 to 3.0:1.

2. The two-component composition as claimed in claim 1, wherein in at least one of the one or more aqueous emulsion copolymer of component A), the mole ratio of t-butyl hydroperoxide to ascorbic acid reducing agent in the aqueous emulsion copolymer ranges from greater than 1.0:1 to 2.5:1.

3. The two-component composition as claimed in claim 1, wherein at least one of the one or more aqueous emulsion copolymer of component A) has a residual (meth)acrylamide content of less than 20 ppm.

4. The two-component composition as claimed in claim 1, wherein at least one of the one or more aqueous emulsion copolymer of component A) has a tetrahydrofuran insoluble content of from 45 to 90 wt. %.

5. The two-component composition as claimed in claim 1, wherein at least one of the one or more aqueous emulsion copolymer of component A) comprises the copolymerization product of (i) one or more nonionic (meth)acrylic monomers chosen from butyl acrylate, ethyl acrylate 2-ethylhexyl acrylate, fatty C.sub.12 to C.sub.18 (meth)acrylates, and mixtures thereof.

6. The two-component composition as claimed in claim 1, wherein at least one of the one or more aqueous emulsion copolymer of component A) comprises the copolymerization product of one or more monomers (i), (ii), (iii) and, in addition, (iv) one or more hydroxyalkyl (meth)acrylate monomers.

7. The two-component composition as claimed in claim 6, wherein in at least one of the one or more aqueous emulsion copolymer of component A), comprises the copolymerization product of from 0.1 to 1.5 wt. % of (iv) one or more hydroxyalkyl (meth)acrylate, all wt. %s of monomers based on total monomer solids.

8. The two-component composition as claimed in claim 1, wherein in at least one of the one or more aqueous emulsion copolymer of component A) comprises the copolymerization product of (ii) one or more vinyl aromatic monomers chosen from styrene, alkyl substituted styrene, vinyl toluene and mixtures thereof.

9. The two-component composition as claimed in claim 1, wherein in at least one of the one or more aqueous emulsion copolymer of component A), the t-butyl hydroperoxide is present in an amount of from 0.2 to 2.5 wt. % or the ascorbic acid reducing agent is present in an amount of from 0.1 to 1.0 wt. %, all amounts as solids based on the total monomer solids used to make the aqueous emulsion copolymer.

10. The two-component composition as claimed in claim 1 comprising from 10 to 60 wt. %, as solids, of the one or more aqueous emulsion copolymer of component A), based on the total solids content of the composition.

11. A methods of making an aqueous emulsion copolymer of component A) having a residual (meth)acrylamide content of less than 40 ppm, preferably, less than 20 ppm comprise addition polymerizing, preferably, gradual addition polymerizing, a reaction medium of a monomer mixture of (i) from 60 to 89.9 wt. % of one or more nonionic meth)acrylic monomers, (ii) from 10 to 40 wt. % of one or more vinyl aromatic monomers, (iii) from 0.1 to 3 wt. % or, preferably, of one or more monomers chosen from amides of 4-unsaturated C.sub.3 to C.sub.6 carboxylic acids and mixtures thereof with itaconic acid or methacrylic acid, all wt. %s of monomers based on the total monomer solids used to make the monomer emulsion, in the presence of an initiator or a redox pair, thereby creating an exotherm and raising for a time period the temperature of the reaction medium to form an aqueous emulsion copolymer composition, after the temperature of the reaction medium stops rising, charging to the aqueous emulsion copolymer composition t-butyl hydroperoxide and a reducing agent, and, then feeding to the composition an ascorbic acid reducing agent, wherein the amount of the ascorbic acid reducing agent ranges from 0.1 to 1.0 wt. %, based on the total monomer solids used to make the aqueous emulsion copolymer, and the amount of the t-butyl hydroperoxide ranges from 0.2 to 2.5 wt. %, based on the total monomer solids used to make the aqueous emulsion copolymer.

Description

EXAMPLES

[0067] The following examples are provided for illustrative purposes only and are not intended to limit the scope of the claims that follow.

[0068] Unless otherwise indicated, all parts and percentages are by weight, all temperatures are at room temperature (RT), and all pressures are at standard pressure.

Synthesis Example 1

Making the Aqueous Emulsion Copolymer in Example 1

[0069] A multi-neck reaction flask was charged with 600 g deionized (DI) water. The necks were set up to accommodate an overhead mechanical stirrer, a nitrogen inlet, a thermocouple, a condenser, and two inlets for the addition of reactants via pump. A monomer emulsion of 397 g water, 35.9 g FES 993 (sodium lauryl ethoxy (EO) ether sulfate, 12 EO Units, BASF SE, Ludwigshafen, DE), 26.2 g Tergitol 15-S-40 (secondary alcohol ethoxylate40 EO units, 70 wt. % in water, The Dow Chemical Company, Midland, Mich.), and a monomer mixture of 1542 g butyl acrylate (BA), 282 g styrene (STY), 35.5 g acrylamide (AM), and 9.31 g 2-hydroxyethyl methacrylate (HEMA) was prepared.

[0070] The reaction flask was heated to 88 to 94 C. before 54.7 g of a 9% sodium bicarbonate solution, 94.7 g of the monomer emulsion, and 20 g of 9% sodium persulfate solution in water were added to the flask. After the resulting exotherm, the remainder of the monomer emulsion and 120 g of a 4.9 wt. % solution of sodium persulfate in water were added over a period of 180 min while maintaining a temperature of 87 to 92 C. preferably 90 C. After the end of feeds, the reaction was held at 80 to 90 C. for approximately 30 min before being cooled to 73 to 77 C. Then 14.8 g of 6.2 wt. % t-butyl hydrogen peroxide solution in water and 14.6 g of 4.6 wt. % sodium bisulfite solution in water were added to the flask as a shot chase. The reaction was hold at 75 C. for 15 min and then was cooled to 60 C. 53 g of 18.4 wt. % t-butyl hydrogen peroxide and 59.8 g of 11.2 wt. % isoascorbic acid solutions in water were added via pump over 1 hour (h). The product of the reaction had solids content ranging from 55 to 58% and a pH below 5. The chase package with mol ratio of oxidant (tert-Butyl hydrogen peroxide, t-BHP) to reductant (Isoascorbic acid) more than 1:1 preferably, from 1:1 to 2.5:1 was used. The molar mass of isoascorbic acid is 176.1 g/mol. Molar mass of tert-Butyl hydrogen peroxide is 90.1 g/mol.

Synthesis Example 2

Making the Aqueous Emulsion Copolymer of Example 2

[0071] The copolymer was made in the manner disclosed Synthesis Example 1, except that the monomer mixture was used as stated in Table 1 below

Synthesis Example 3

Making the Aqueous Emulsion Copolymer of Example 3

[0072] The copolymer was made in the manner disclosed Synthesis Example 1, except that the chase package with the mol ratio of oxidant (tert-Butyl hydrogen peroxide, t-BHP) to isoascorbic acid) equal to 1 was used as stated in Table 1 below.

Aqueous Emulsion Copolymers of Comparative Examples 1 and 2

[0073] The aqueous emulsion copolymer having the monomer mixture and reagents as listed in Table 1, below, was made by single stage gradual addition emulsion polymerization in the presence of an acrylic emulsion polymer seed, an anionic surfactant and a 15% sodium persulfate solution in water. The emulsion copolymer was cooled to 60 to 70 C. and then residual monomers were chased through the addition of the indicated oxidants and reductants.

[0074] In Comparative Example 2, the chase comprised addition of an aqueous solution containing 3 wt % t-butyl hydrogen peroxide and 0.5 wt % hydrogen peroxide and, in parallel, a 4 wt % solution of isoascorbic acid to the flask over a period of 0.75 to 1 hour. The final mixture had solids content ranging from 50 to 55% and a pH of above 5. Table 2, below, discloses the fast curing dry mix powder composition formulations used in the Examples.

[0075] The amount of tetrahydrofuran insoluble content in both comparative and inventive aqueous emulsion copolymers, as determined gravimetrically and compared using size exlusion chromatography (SEC), as defined above. Table 1, below, reports various properties of the aqueous emulsion copolymer.

TABLE-US-00001 TABLE 1 Emulsion Polymer Compositions Aqueous Emulsion Example 1 Example 2 Comp Comp Copolymer (Tg 23 C.) (Tg 12 C.) Example 3 1* 2* Monomers Butyl acrylate 82.5 70 82.5 70 82.5 Styrene 15.1 28.3 15.1 28.3 15.1 Acrylamide 1.9 1.95 1.9 1.95 1.9 2-hydroxyethyl 0.5 0.5 0.5 0.5 0.5 methacrylate Surfactants FES 993 (sodium 0.54 0.54 0.54 0.54 0.54 lauryl ether sulfate - 12 EO Units) Tergitol 15-S-40 0.98 0.98 0.98 0.49 0.49 Chase Package Sodium bisulfite 0.04 0.04 0.04 0.21 0.21 Isoascorbic acid 0.36 0.36 0.18 0 0.14 t-Butyl 0.4 0.4 0.36 0.15 0.36 hydroperoxide Properties.sup.1 Measured Tg ( C.) 30.3 11.8 ~30 12.6 ~30 Residual Monomers Butyl acrylate 3 ppm 4 ppm 31 ppm 240 ppm 4894 ppm Styrene 1 ppm 16 ppm 0.7 ppm 2 ppm 33 ppm Acrylamide 0.2 ppm 1 ppm 64 ppm 1 ppm 635 ppm % THF.sup.1 Insoluble 78% 57% 66% 23% 54% Content .sup.1THF = tetrahydrofuran; 2. For all properties with ranges given in the Comparative Examples, the ranges given are target values for the emulsion polymers which the inventors used; no measurements were taken for these polymers.

[0076] As shown in Table 1, above, the inventive copolymers have a much lower residual monomer content, especially in acrylamide, than do the comparatives. Also, the inventive polymers have a much higher tetrahydrofuran insoluble content.

[0077] To formulate the waterproofing membrane compositions or mortars, 40 weight parts active content of the aqueous emulsion copolymer indicated in Table 1, above, as solids, and 100 weight parts fast curing dry mix powder composition solids as indicated in Table 2, below, were combined with 32 weight parts water (from wet aqueous emulsion copolymer plus additional water as needed, as described below). Test results are reported in Table 3, below.

TABLE-US-00002 TABLE 2 Fast Cure Dry Mix Formulation FAST DRY MIX Ingredients Wt. % % Ordinary Portland Cement (OPC CEM I 42.5R.sup.1) 25.30 Calcium Aluminate Cement (CAC Ternal.sup.,2 RG) 12.00 Snow White.sup., 3 filler (CaSO.sub.4) 2.70 Quarzsand.sup., 4 F32 (average PS 0.24 mm) 36.40 Quarzsand.sup., 4 F36 (average PS 0.16 mm) 23.45 WALOCEL.sup., 5 MKX 6000 PF01 0.15 .sup.1OPC CEM I 42.5R (From Heidelberger, Germany); OPC CEM I = Ordinary Portland Cement type I Comprising Portland Cement and up to 5% of minor additional constituents. 42.5R - Compressive strength >42.5 after 28 d; .sup.2CAC Ternal RG Kerneos SA, France (Calcium Aluminate Cement clinker >99.5 wt. %); .sup.3Snow White Filler, USG, CaSO4 >97.68%; .sup.4Quarzsand FH 32/FH36, Quarzwerke GmbH, Germany; .sup.5Walocel MKX 6000 PF 01 Hydroxyethyl methyl cellulose (HEMC) thickener powder giving a viscosity of 60000 cps (Haake, 2.55 reciprocal seconds) in a 2 wt % solution in water at room temperature (Dow Chemical, Midland MI); .sup.6Arbocel PWC 500, J. RETTENMAIER & SHNE GMBH + CO, Germany. Natural cellulose fibers; .sup.7Finntalc M15, MONDO MINERALS B.V. Netherlands, Mg-silicate.

[0078] To form the fast curing dry mix powder composition component, the cement, sand and thickener were weighed and placed into a plastic (polyethylene) bag and then hand mixed for 2 minutes and conditioned at room temp (23 C.) for 24 hrs. After 24 hours, the aqueous emulsion copolymer component was prepared by adding the indicated amount of water into a 2 l polyethylene beaker and stirring for 30 seconds at 200 rpm with a 4-wing stirrer (diameter: 75 mm). Then, fast curing dry mix powder component was added within 45 s to the wet component. Stirrer speed was increased continuously from 200 up to 750 rpm to have a good vortex in the mass. After combining all components, the paste was stirred for additional 135s at 750 rpm to form a mortar.

[0079] After stirring was finished, if needed, a waterproofing membrane was formed from the mortar, as set forth in the test methods below.

Test Methods

[0080] Appearance (including cracks): A waterproofing membrane was formed by planing the indicated mortar material with a smoothing trowel to cover the area bounded by two 200 mm10 mm2.6 mm thick metal slats fixed on opposite (widthwise) sides of a continuous polytetraflouroethylene film substrate (Bytac VF-81, SPI Supplies, West Chester, Pa.) resting on a 300250 mm10 mm thick poly(vinyl chloride) plate support. Each membrane was dried, the two slats removed, and the membranes were carefully removed from the film substrate after 2 days. The membranes were inspected for the number and appearance of small cracks (<5 mm long), large cracks (>5 mm long), deep cracks and overall appearance. The film substrate was inspected for cracks that might get reproduced in the waterproofing membrane coated on the substrate so that there were no cracks in the substrate film that would influence the tensile test.

[0081] Elongation/Tensile Strength: (DIN ISO EN 527-1 and DIN ISO EN 527-2, March, 2010) 2.6 mm thick membranes of each indicated material were made as described in the Appearance test, above. The specimens cured under conditions of 7 days storage at 23 C./50% rel. humidity (RH), 7 days storage at 23 C. (RT)/50% RH followed by 7 days at 23 C. under water and 28 days at 23 C. (RT)/50% RH (7 days followed by 21 more days). After the 7 day RT cure, each of the cured membranes was then cut into twenty one dumbbell shape specimens each having dimensions of (14 mm)/twenty one (21 mm), according to DIN ISO EN 527-2, type 1B (80 mm L15 mm W with a narrow center section that is 10 mm W and 20 mm L). Seven (7) specimens of each cured membrane were tested immediately; seven (7) specimens of each cured membrane were cured 7 days under water at RT and then tested. Another seven (7) specimens were cured 21 more days at RT and 50% RH. To test, for each specimen thickness and width was measured at the thin part of the specimen 3 times for calculation of the sectional area before elongation. Elongation and tensile tests were run in a texture analyzer (TA.XT.plus Texture Analyser, Winopal Forschungsbedarf GmbH, Ahnsbeck, DE) at a speed of 20 mm/min and controlled via computer. Each specimen was fixed in the two clamps of texture analyser (60 mm distance between clamps). Measured was the distance between the clamps over time with the corresponding force needed to elongate the specimen elongated. The readings taken were maximum force; distance at maximum force and the distance at break (the distance at 50% max. force before break was taken, as this could be easy detected). From these readings, the percent elongation and maximum tensile strength, elongation at break and e-modulus or slope of the curve plotted as tensile strength vs. elongation were calculated. Reported values for each indicated material was the average of the seven (7) results calculated from readings for each specimen tested.

[0082] Acceptable tensile strength (28 d) is 0.4 N/mm.sup.2 (MPa); Acceptable Elongation (28 d) is 8%.

[0083] Crack Bridging: According to EN 14891 (March, 2010). For each indicated mortar, concrete specimens (1605012 mm) were made from a mix of 28.9wt. % CEM I 52.5R, 57.8 wt. % quartz sand F36, 0.3 wt. % superplasticiser (Glenium 51, BASF, Ludwigshafen, DE) and 13 wt. % water and cured 2 days at 23 C./50% rel. humidity and 26 days under water at 23 C. Once the concrete specimens were cured, each indicated freshly prepared mortar was applied to one concrete specimen using a metal frame of 3 mm thickness to one of the 16050 mm sides of the specimen and allowed to dry for 4 h. Then, each freshly prepared mortar was applied to the other side of the specimen on which the same mortar had been applied using the same frame. Each specimen was cured 7 days at 23 C./50% rel. humidity. After curing, each cured specimen was broken carefully according to EN 14891(March, 2010) without destroying the membrane. The broken concrete specimen with the intact membrane was elongated with the texture analyzer at a speed of 0.15 mm/min, and the surface of the membrane was monitored visually. The reported distance was (1) at maximum force (2) when the first cracks appear. Additionally the maximum force was reported. An acceptable result is 0.75 mm.

[0084] Density: Immediately after mixing, mortars were placed into a 100 ml steel beaker container of known volume and weight (inside diameter: 54 mm, height: (inside): 43.7 mm, wall thickness: 1.6 mm), tamped down, and then weighed. Density of the mortar is the weight divided by the volume of the mortar.

[0085] Time needed to apply second layer: The indicated freshly prepared mortar was applied at 1.3 mm thickness in one layer onto a lime stone brick. By a finger tip test every 5 min the freshness of the membrane was checked. When the membrane is set to the finger tip it is possible to apply a second layer and this time was recorded.

[0086] Water Impermeability: According to EN 12390-8 (March, 2010) A hole was drilled in a lime stone brick on the obverse side of the testing surface (nearly piercing1 cm away from the testing surface). The indicated freshly made mortar was applied at 1.3 mm thickness in one layer on the lime stone brick. After 4 h a second layer of a freshly made mortar was applied at an added 1.3 mm on the first layer and allowed to dry for 7 days at 23 C. and 50% rel. humidity. A water indication paper (Wator 90610, Macherey-Nagel, Dueren, DE) was put into the drilled hole and then the membrane with the lime stone was put into the water impermeability tester (supplier: TESTING Bluhm & Feuerherdt GmbH, Berlin, DE) and a hydrostatic pressure of 1.5 bars was put on the membrane for 4 days. If the water absorption was less than 25 ml the pressure was raised up to 5 bars for 3 days. If the absorption was higher the pressure was held additional 3 days at 1.5 bar. After the 7 days the water indication paper was checked. The test is passed if no humidity is seen underneath the membrane. In parallel the water loss over time was read from the calibrated cylinder of the water impermeability tester. In most cases, the membrane is water impermeable if water loss is below 30 ml after 7 days exposure.

[0087] Water Absorption: The indicated freshly prepared membrane mortar was applied at 2.6 mm thickness in one layer onto a polytetrafluoroethylene film (supported by a PVC or glass plate) to form a wet membrane. The membrane was allowed to cure for 7 days at 23 C./50% rel. humidity. After curing, 5 pieces of 55 cm size were cut out of the membrane, weighed and immersed in water. After 1 and 7 days, the specimens were taken out of the water, the surface of each specimen was carefully dried with a tissue and the specimens were weighed. The water uptake in percent is calculated as the ratio of weight increase divided by the weight before immersing. Less than 5% after 24 h and less than 10% after 7 days is acceptable.

[0088] W/S: Water to solid ratio (W/S) ratio is calculated by taking the ratio of total amount of water to the total amount of solids coming from the emulsion copolymer and drymix.

[0089] Table 3, below, gives test results for each indicated mortar or membrane.

[0090] As shown in Table 3, below, inventive Examples 2 show that a second mortar layer can be applied in 45 min or less to the first applied layer. The Comparative Example 1 mortar creates cracks as it cures, whereas the mortars of inventive Example 2 does not crack as it cures. The water permeable membrane having the inventive polymer of Example 2 provides superior elongation at max force and rupture, as well as maximum force in comparison to the same composition made with the polymer of Comparative Example 1 which was not made with the inventive amount of t-butyl hydroperoxide or with a greater amount of t-butyl hydroperoxide than reducing agent. Finally, the membranes made from the mortars of Example 2 exhibits dramatically improved crack bridging when compared to Comparative Example 1, both in terms of deformation at maximum force and at rupture.

TABLE-US-00003 TABLE 3 Results TEST Ex 2 Comp 1* COMP 2* Ex 1 Water/Solids 0.219 0.256 0.226 0.229 Density (g/cm.sup.3) 1.39 1.10 1.37 1.35 (immediate) Time needed to 45 35 80 80 apply second layer (min) Appearance slightly rough, white spotty nice even slightly rough, but nice and surface but but nice and even surface very soft, few even surface front and lumbs front & backside is moderate backside is shiny rough shiny, slightly sticky after 7 days Cracks polytetrafluoroethylene no like dry river no no bed limestone no ok no no Water Absorption (5 5 cm 7 d NK+ (%) after 1 day water 3.5 13.9 5.4 5.4 storage after 7 days water 8.5 20.5 13.1 13.4 storage Remark after 7 days clear clear clear clear H.sub.2O Elongation (water immersion, 7 d at RT and 50% RH/7dH.sub.2O) tensile strength (max 1.11 No 0.46 0.71 force, N/mm.sup.2) average elongation 106.5 No 66.1 66 % at max. force average elongation 129 n/a 87.8 74 % at rupture Elongation (@ 20 C.) tensile strength (max n/a n/a 3.27 2.47 force, N/mm.sup.2) average elongation n/a n/a 41 65 % at max. force average elongation n/a n/a 46.9 74 % at rupture Crack Bridging (after 7 days at RT and 50% RH) max force (N) 125 64 75 88 deformation at max 2.84 0.93 1.21 1.58 force (mm) deformation at 6.47 1.86 2.67 3.22 rupture (mm) *Comparative Example.