HIGH SOLIDS POLYCARBOXYLATE SYNTHESIS FOR CEMENT SUPERPLASTICIZERS

Abstract

The present invention provides efficient methods to form a high solids content polymeric polyacid or a comb polymer useful as a superplasticizer or dispersant which comprise heating to from 80 to 100 C for a first time period, and then, sequentially, heating to a second temperature of from 150 to 250 C. for a second time period a wet reaction mixture having a solids content of from 80 to 99 wt. % and comprising from 15 to 60 wt. % of one or more ethylenically unsaturated acid or a salt thereof, from 37 to 76.99 wt. % of one or more polyether polyols, alkyl polyether polyols, polyether amines or alkyl polyether amines in the presence of (i) from 0.01 to 1 wt. %, of one or more water soluble radical initiators or redox pairs and (ii) from 2 to 22 wt. % of one or more phosphorus oxide containing compounds, all weights based on the total weight of the wet reaction mixture.

Claims

1. A method for making a polycarboxylate or polycarboxamide ether comprising: heating to a temperature of from 80 to 100 C. for a first time period of 5 to 300 minutes, and then, sequentially, heating to a second temperature of from 150 to 250 C. for a second time period of from 30 to 600 minutes a reaction mixture in water (wet reaction mixture) having a solids content of from 80 to 99 wt. % of the reaction mixture comprising from 15 to 60 wt. %, based on the total weight of the wet reaction mixture, of one or more ethylenically unsaturated acid or a salt thereof, from 37 to 76.99 wt. %, based on the total weight of the wet reaction mixture of one or more polyether polyols, alkyl polyether polyols, polyether amines or alkyl polyether amines, in the presence of (i) from 0.01 to 1 wt. %, based on the total weight of the wet reaction mixture, of one or more water soluble radical initiators or redox pairs and in the presence of (ii) from 2 to 22 wt. %, based on the total weight of the wet reaction mixture, one or more phosphorus oxide containing compounds chosen from a hypophosphite, such as sodium hypophosphite, or an organic phosphite to form a comb polymer.

2. The method as claimed in claim 1, wherein the solids content of the wet reaction mixture ranges from 90 to 99 wt. %.

3. The method as claimed in claim 1, wherein the heating during the second time period takes place under a partial vacuum of from 10 to 300 mm/Hg.

4. The method as claimed in claim 1, wherein the one or more ethylenically unsaturated acid is chosen from methacrylic acid, a salt thereof, or a mixture of methacrylic acid with acrylic acid.

5. The method as claimed in claim 1, wherein the total amount of the of one or more polyether polyols, alkyl polyether polyols, polyether amines or alkyl polyether amines that is a diol or difunctional amine is 3 wt. % or less, based on the total weight of the one or more polyether polyols, alkyl polyether polyols, polyether amines or alkyl polyether amines.

6. The method as claimed in claim 1, wherein the weight average molecular weight of the one or more polyether polyols, alkyl polyether polyols, polyether amines or alkyl polyether amines ranges from 200 to 5000.

7. The method as claimed in claim 1, wherein the ratio of moles of carboxyl or carboxylate groups of ethylenically unsaturated acid to moles of amine or hydroxyl groups in the total wet reaction mixture ranges from 9:1 to 1:1.

8. The method as claimed in claim 1, wherein the comb polymer has a weight average molecular weight of from 6,000 to 160,000.

9. The method as claimed in claim 1, wherein the wet reaction mixture is free of added organic solvent.

10. The method as claimed in claim 1, comprising charging all of the total phosphorus oxide containing compound into the wet reaction mixture or vessel prior to heating.

Description

SYNTHESIS OF EXAMPLE 1: PMAA POLYMER WITH 9 WT. % CHAIN TRANSFER AGENT (CTA) HALF CHARGED AND HALF FED, MADE IN MPEG 2,000

[0054] To a 5 L reaction kettle under a nitrogen sweep was charged all of the phosphorus oxide containing compound as indicated in Table 1, below, and the indicated methylpolyethylene glycol having a molecular weight of 2,000 (mPEG 2000) which was allowed to melt while heating to 97 C., when melted stirring was started and then the indicated phosphorus oxide containing compound, sodium hypophosphite (NaHP) was charged. Then, the indicated initiator, sodium persulfate (NaPS) and methacrylic acid (MAA) monomer was fed to the kettle over 120 minutes, feeding the monomer on the surface of kettle contents. At the same time, in parallel, the indicated phosphorus oxide containing compound (NaHP) was fed over a period of 95 minutes. The reaction temp. was maintained at 97 C. during the feeds. At end of feeds, the temperature was held @ 97 C. for 20 more minutes.

TABLE-US-00001 TABLE 1 Synthesis of pMAA at 94 wt. % Solids Solids Tot. Wt. Wt. Material Conc. (g) (g) mPEG 2,000 100.0% 1247.4 1247.4 CTA NaHP (aqueous) 45.0% 37.42 83.2 DI Rinse H.sub.2O 0.0% 0.0 5.0 Monomer Feed MAA 100.0% 831.6 831.6 DI Rinse H.sub.2O 0.0% 0.0 5 CTA Cofeed SHP (aqueous) 45.0% 37.42 83.2 DI Rinse H.sub.2O 0.0% 0 2.5 Initiator Cofeed NaPS (aqueous) 45.0% 24.9 55.43 DI Rinse H.sub.2O 0.0% 0.0 5.0 Wt. % Solids 94.0% 2178.8 2318

SYNTHESIS OF EXAMPLE 2: PMAA POLYMER WITH CHAIN TRANSFER AGENT (CTA) HALF CHARGED AND HALF FED MADE IN MPEG 2,000

[0055] To a 5 L reaction kettle under a nitrogen sweep was charged half the phosphorus oxide containing compound as indicated in Table 2, below, and the indicated methylpolyethylene glycol having a molecular weight of 2,000 (mPEG 2000) which was allowed to melt while heating to 97 C., when melted stirring was started. Then, the indicated initiator and methacrylic acid (MAA) monomer was fed to the kettle over 120 minutes, feeding the monomer on the surface of kettle contents. At the same time, in parallel, the indicated phosphorus oxide containing compound (NaHP) was fed over a period of 105 minutes. The reaction temp. was maintained at 97 C. during the feeds. At end of all feeds, the temperature was held @ 97 C. for 20 more minutes.

TABLE-US-00002 TABLE 2 Synthesis of PMAA at 96.1 wt. % Solids Charge Conc. Sols. Wt. Tot. Wt. mPEG 2,000 100.0% 1247.4 1247.4 CTA NaHP 45.0% 18.72 41.6 DI Rinse H.sub.2O 0.0% 0.0 2.5 Monomer Feed MAA 100.0% 415.8 415.8 DI Rinse H.sub.2O 0.0% 0.0 2.5 CTA Cofeed NaHP 45.0% 18.72 41.6 DI H.sub.2O DI Rinse H.sub.2O 0.0% 0.0 1.2 Initiator Cofeed NaPS 100.0% 12.5 12.47 DI H.sub.2O 0.0 15.24 DI Rinse H.sub.2O 0.0% 0.0 2.5 Dilution Water DI H.sub.2O 0.0% 0.0 Wt. % Solids = 96.1% 1713.1 1783

SYNTHESIS OF EXAMPLE 3 PCE: PMAA POLYMER WITH 9% CHAIN TRANSFER AGENT (CTA) MADE IN MPEG 2,000

[0056] To a 5 L reaction kettle under a nitrogen sweep was charged the methylpolyethylene glycol having a molecular weight of 2,000 (mPEG 2000) as indicated in Table 3, below, and all of the indicated phosphorus oxide containing compound. The mPEG was allowed to melt while heating to 97 C., when melted stirring was started. Then, the indicated initiator and methacrylic acid (MAA) monomer was fed to the kettle over 120 minutes, feeding the monomer on the surface of kettle contents. At the same time, in parallel, the indicated initiator was fed over a period of 120 minutes. The reaction temp. was maintained at 97 C. during the feeds. After 1.5 hours of polymerization, 15 grams of DI water was charged and an additional 10 grams of DI water was charged at 1.75 hours, this is listed as dilution water in Table 3, below. After polymerization of the polyacid, 1435 additional grams of mPEG 2,000 was added and the mixture was heated to 180 C. for 3 hours under 20 inHg of vacuum.

TABLE-US-00003 TABLE 3 Synthesis of PMAA at 91.6 wt. % Solids Charge Conc. Sols. Wt. Tot. Wt. mPEG 2,000 100.0% 499.0 499.0 CTA NaHP 45.0% 29.97 66.6 DI Rinse H.sub.2O 0.0% 0 2 Monomer Feed MAA 100.0% 332.6 332.6 DI Rinse H.sub.2O 0.0% 0 2 Initiator Cofeed NaPS 45.0% 10.0 22.17 DI Rinse H.sub.2O 0.0% 0 2 Dilution Water DI H.sub.2O 0.0% 0 25 Wt. % Solids = 91.6% 871.5 951

SYNTHESIS EXAMPLE 4 PCE: PMAA POLYMER WITH 9% CHAIN TRANSFER AGENT (CTA) MADE IN MPEG 2,000

[0057] To a 5 L reaction kettle under a nitrogen sweep was charged the indicated methylpolyethylene glycol having a molecular weight of 2,000 (mPEG 2000), polypropylene glycol 2000, and all of the phosphorus oxide containing compound (NaHP) indicated in Table 4, below. The mPEG was allowed to melt while heating to 97 C., when melted stirring was started. Then, the indicated initiator and methacrylic acid (MAA) monomer was fed to the kettle over 120 minutes, feeding the monomer on the surface of kettle contents. At the same time, in parallel, the indicated intiator was fed over a period of 120 minutes. The reaction temp. was maintained at 97 C. during the feeds. After polymerization of the polyacid, the mixture was heated to 180 C. for 2.75 hours under 20 inHg of vacuum. The reaction was stopped due to excessive crosslinking as noted by a significant increase in viscosity.

TABLE-US-00004 TABLE 4 Synthesis of PMAA at 95.7 wt. % Solids Total Charge Conc. Sols. Wt. Weight PPG 2,000 100.0% 72.6 72.6 mPEG 2,000 100.0% 1469.9 1469.9 CTA NaHP 45.0% 61.1 61.1 DI Rinse H.sub.2O 0.0% 0 5 Monomer Feed MAA 100.0% 305.7 305.7 DI Rinse H.sub.2O 0.0% 0 0 Initiator Cofeed NaPS 45.0% 9.2 20.3 DI Rinse H.sub.2O 0.0% 0 0 Dilution Water DI Rinse H.sub.2O 0.0% 35.1 Total 1884.9 1969.8

[0058] From the synthesis Examples 1, 2, 3, and 4, the GPC Weight average molecular weight data for polymeric polyacids that result from heating for the first time period is as follows:

TABLE-US-00005 TABLE 5 Weight Average Molecular Weights of pMAA (Before Esterification) Example Description Mw 1 42% pMAA synthesized in mPEG 2000, 50/50 10,197 NaHP precharge/cofeed 2 24% pMAA synthesized in mPEG 2000, 50/50 26,613 NaHP precharge/cofeed 3 42% pMAA synthesized in mPEG 2000, 100% 6,969 NaHP precharge 4 15.5% pMAA synthesized in mPEG 2,000 and 16,675 PPG 2,000, 100% NaHP precharge

[0059] From Table 5, above, it is apparent that in all Examples, a polymeric polyacid results from the methods wherein the wet reaction mixture is heated for the first time period. Thus, in accordance with the present invention, one can form a polymeric polyacid with very little water and, thereby, enable economical formation of comb polymers or PCEs at the second temperature. Example 1 shows the advantage of increasing the content of the ethylenically unsaturated acid relative to the content of the polyether containing compound, giving a lower, more controlled molecular weight. Example 3 shows the advantage of charging all of the phosphorus oxide containing compound with the polyether containing compound prior to feeding ethylenically unsaturated acid and heating for the first period, thereby giving a lower molecular weight polymeric polyacid in comparison to inventive Example 1.

[0060] Applications Testing:

[0061] The comb polymers (PCE) made from the methods in Examples 3 and 4 were tested in concrete. All PCEs were formulated in a 3:1 mixture of sand to cement (50-30 Unimin sand (Unimin Corp., New Canaan, Conn.) and Type I Grey Portland Cement) at a constant water level of 42 wt. % on cement with Deefo PI-35 Defoamer (Munzing, Bloomfield, N.J.) at 1.0 wt. % on PCE solids. Immediately after mixing, the wet mortar samples were placed and packed in brass flow molds (10 cm diameter base) on the plate of a motorized flow table. After tamping, the molds were removed from the wet mortar and the de-molded samples were subjected to 25 table drops. After the dropping process was completed, the samples were measured with the mortar diameter check calipers for flow differences and recorded. Acceptable results are diameters at least 10% greater than the control. The testing was performed using guidelines of test method ASTM-1437-13 (2013), Flow of Hydraulic Cement Mortar.

[0062] Table 6, below, shows the results of the methods of the present invention compared to no added PCE and to other known methods where cleavage of a polyether to make it difunctional is required. Table 6 shows that a comparative Example 4 made with a diol (PEG) or cleaved alkyl polyether rather than with an alkylpolyether mono-ol provided no slump or cement flow compared to the control without any PCE. Meanwhile, the inventive Example 3 polymer made with an alkylpolyether mono-ol successfully performed as a PCE and improved the flow of the cement.

TABLE-US-00006 TABLE 6 Slump Test Results Example Diameter *No PCE 10.3 3 12.4 *4 10.4 *indicates Control.