Ester-ether composite polycarboxylate water reducer and preparation method thereof

Abstract

The invention discloses an ester-ether composite polycarboxylate water reducer and a preparation method thereof. In order to make the molecular structure of the ether bond functional group and the ester bond functional group be 1:1, the method selects 3,4-epoxyhexane esterification, and under the catalytic condition of an anion alkali metal catalyst, uses an unsaturated ene alcohol compound as an end group initiator to synthesize an unsaturated polyoxyethylene ether containing both an ester bond and an ether bond; and synthesizes a polycarboxylate high-efficiency water reducer with better slow-setting and slump-retaining performance and anti-mud performance by free radical copolymerization of the synthesized unsaturated polyoxyethylene ether containing both an ester bond and an ether bond and an unsaturated carboxylic acid organic matter.

Description

Technical Field

[0001] The invention relates to the technical field of polycarboxylate water reducer preparation, and in particular to an ester-ether composite polycarboxylate water reducer and a preparation method thereof. Background Art

[0002] As researchers delve deeper into the field of polycarboxylic acid water reducers, many researchers have found that the performance of polycarboxylic acid high-efficiency water reducers is closely related to their molecular structure. Therefore, the molecular structure design of polycarboxylic acid water reducers is of great significance for exploring the relationship between structure and performance. In previous studies on polycarboxylic acid high-efficiency water reducers, it is generally believed that ether functional groups have a better effect of retarding setting and retaining collapse for the synthesized polycarboxylic acid water reducers. However, for concrete applications with high mud content, ether monomers have poor mud resistance; polycarboxylic acid water reducers with ester functional groups have better compatibility and anisotropy, and can be effectively used in concrete projects with high mud content.

[0003] In the prior art, polycarboxylate water reducers are designed according to the reactant ratio, reaction conditions and synthesis process for specific construction projects or application requirements, and usually can only be adjusted slightly, which is not conducive to increasing the scope of application of the process. In the prior art, unsaturated carboxylic acid compounds (acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, etc.) are usually reacted with unsaturated alcohol polyethers (such as isopentyl unsaturated alcohol polyethers (TPEG), isobutylene unsaturated alcohol polyethers (HPEG), propylene unsaturated alcohol polyethers (APEG), etc.).

[0004] In the prior art, there are reports on ester-ether composite polycarboxylic acid water-reducing agents. In the related technical solutions, both ester unsaturated monomers and ether unsaturated monomers need to be used. However, in the technical solutions described in the prior art, there are differences in the reactivity ratios of unsaturated ester monomers and unsaturated ether monomers, and there are also differences in the initiator systems and reaction conditions applicable to ester monomers and ether monomers. Therefore, the polycarboxylic acid-based high-efficiency water-reducing agent synthesized by the prior art solution cannot achieve the ideal molecular structure design of 1:1 between ester bond functional groups and ether bond functional groups, and thus cannot achieve the best anti-mud and slow-setting and slump-retaining performance. Summary of the invention

[0005] The purpose of the present invention is to provide an ester-ether composite polycarboxylic acid water-reducing agent and a preparation method thereof in view of the deficiencies in the prior art.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] The first aspect of the present invention is to provide a method for preparing an ester-ether composite polycarboxylate water-reducing agent, comprising the following steps:

[0008] Step 1, using an unsaturated enol compound as a reaction raw material, adding an alkali metal alcoholate as a catalyst, and carrying out an anionic ring-opening polymerization reaction with 3,4-epoxyhexane ester, and adjusting the pH to 8-12 after the reaction is completed to obtain an unsaturated polyoxyethylene ether containing both ester bonds and ether bonds;

[0009] Step 2: The unsaturated polyoxyethylene ether prepared in step 1 is subjected to free radical copolymerization reaction with an unsaturated carboxylic acid compound, and after the reaction, the pH is adjusted to 5.0-6.5 to obtain an ester-ether composite polycarboxylic acid-based high-efficiency water reducer.

[0010] Furthermore, the 3,4-epoxyhexane ester is 3,4-epoxyhexane methyl ester or 3,4-epoxyhexane ethyl ester or a mixture of the two.

[0011] Furthermore, in the step 1, the reaction temperature of the anionic ring-opening polymerization reaction is 120-145° C., the reaction time is 3-7 hours, and the pressure of the reaction device is 1.7-3.8 MPa.

[0012] Furthermore, in the step 1, the amount of the catalyst used is 0.7-2.5% of the total mass of the reactants, and the molar ratio of the unsaturated enolate compound to the 3,4-epoxyhexane ester is 1:(8-25).

[0013] Furthermore, in the step 2, the unsaturated carboxylic acid compound is acrylic acid or methacrylic acid or a mixture of the two.

[0014] Furthermore, in the step 2, the molar ratio of the unsaturated polyoxyethylene ether to the unsaturated carboxylic acid compound is 1:(2.5-5.5).

[0015] Furthermore, in the step 2, the initiators used are hydrogen peroxide and vitamin C, wherein the mass ratio of hydrogen peroxide to vitamin C is 1:(0.2-0.5), and the total amount of the initiator is 0.5-2.5% of the total mass of the reactants.

[0016] Furthermore, in the step 2, the reaction temperature of the free radical copolymerization reaction is 15-35° C., and the reaction time is 90-360 min.

[0017] The second aspect of the present invention is to provide an ester-ether composite polycarboxylate water-reducing agent, which is prepared by the above-mentioned preparation method.

[0018] The present invention adopts the above technical solution, and has the following technical effects compared with the prior art:

[0019] In order to make the molecular structure of ether bond functional groups and ester bond functional groups be 1:1, the present invention selects 3,4-epoxyhexane esterification, and uses unsaturated ene alcohol compounds as terminal initiators to synthesize unsaturated polyoxyethylene ethers containing both ester bonds and ether bonds under the catalytic conditions of anionic alkali metal catalysts; and synthesizes a polycarboxylic acid-based high-efficiency water reducer with better slow-setting and slump-retaining performance and anti-mud performance through free radical copolymerization of the synthesized unsaturated polyoxyethylene ethers containing both ester bonds and ether bonds and unsaturated carboxylic acid organic matter. DETAILED DESCRIPTION

[0020] The following specific embodiments further illustrate the present invention, but are not intended to limit the present invention. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.

[0021] Example 1

[0022] Step 1:

[0023] 0.5 kg of allyl alcohol as a reaction raw material was added to a pressure reaction vessel, and 0.08 kg of metallic sodium alcoholate was added as a catalyst. Mechanical stirring was performed under the reaction condition of 135°C, and the pressure of the reaction device was 2.3 MPa. 5 kg of 3,4-epoxyhexane methyl ester was added to carry out anionic ring-opening polymerization, and the reaction time was 5 hours. After the reaction was completed, the pH was adjusted to 10, and the reaction obtained unsaturated polyoxyethylene ether A1 containing both ester bonds and ether bonds.

[0024] Step 2:

[0025] 0.7 kg of acrylic acid was added to the reaction device, and 10 kg of unsaturated polyoxyethylene ether A1 was added under mechanical stirring conditions. The reaction temperature was controlled to 25°C, and 0.07 kg of hydrogen peroxide and 0.03 kg of vitamin C were added as initiators for free radical copolymerization. The reaction time was 180 min. After the reaction was completed, sodium hydroxide aqueous solution was added to adjust the pH to 6.0 to obtain an ester-ether composite polycarboxylic acid-based high-efficiency water reducer.

[0026] Example 2

[0027] Step 1:

[0028] 0.7 kg of methyl allyl alcohol as a reaction raw material was added to a pressure reaction vessel, and 0.2 kg of metallic sodium alcoholate was added as a catalyst. Mechanical stirring was performed under the reaction condition of 140°C, and the pressure of the reaction device was 3.1 MPa. 14 kg of 3,4-epoxyhexane ethyl ester was added for anionic ring-opening polymerization, and the reaction time was 6 hours. After the reaction was completed, the pH was adjusted to 10, and the reaction obtained an unsaturated polyoxyethylene ether A2 containing both ester bonds and ether bonds.

[0029] Step 2:

[0030] 0.8 kg of methacrylic acid was added to the reaction device, and 15 kg of unsaturated polyoxyethylene ether A2 was added under mechanical stirring conditions. The reaction temperature was controlled to 20°C, and 0.13 kg of hydrogen peroxide and 0.05 kg of vitamin C were added as initiators for free radical copolymerization. The reaction time was 240 min. After the reaction was completed, sodium hydroxide aqueous solution was added to adjust the pH to 6.5 to obtain an ester-ether composite polycarboxylic acid-based high-efficiency water reducer.

[0031] Example 3

[0032] Step 1:

[0033] 0.5 kg of allyl alcohol as a reaction raw material was added to a pressure reaction vessel, and 0.12 kg of metallic sodium alcoholate was added as a catalyst. Mechanical stirring was performed under the reaction condition of 125°C, and the pressure of the reaction device was 2.5 MPa. 7 kg of 3,4-epoxyhexane ethyl ester was added to carry out anionic ring-opening polymerization, and the reaction time was 4.5 hours. After the reaction was completed, the pH was adjusted to 10, and the reaction obtained unsaturated polyoxyethylene ether A3 containing both ester bonds and ether bonds.

[0034] Step 2:

[0035] 0.4kg acrylic acid and 0.5kg methacrylic acid were added to the reaction device, 13kg unsaturated polyoxyethylene ether A3 was added under mechanical stirring, the reaction temperature was controlled to 18°C, 0.12kg hydrogen peroxide and 0.35kg vitamin C were added as initiators for free radical copolymerization, and the reaction time was 270min. After the reaction, sodium hydroxide aqueous solution was added to adjust the pH to 5.5 to obtain an ester-ether composite polycarboxylic acid-based high-efficiency water reducer.

[0036] Example 4

[0037] 0.8 kg of isopentenol as a reaction raw material was added to a pressure reaction vessel, and 0.15 kg of metal sodium alcoholate was added as a catalyst. Mechanical stirring was performed under the reaction condition of 140°C, and the pressure of the reaction device was 2.9 MPa. 6 kg of 3,4-epoxyhexane ethyl ester was added for anionic ring-opening polymerization, and the reaction time was 3.5 hours. After the reaction was completed, the pH was adjusted to 8.5, and the reaction obtained an unsaturated polyoxyethylene ether A4 containing both ester bonds and ether bonds.

[0038] Step 2:

[0039] 0.7 kg of acrylic acid was added to the reaction device, 15 kg of unsaturated polyoxyethylene ether A4 was added under mechanical stirring, the reaction temperature was controlled to 25°C, 0.15 kg of hydrogen peroxide and 0.08 kg of vitamin C were added as initiators for free radical copolymerization, and the reaction time was 210 min. After the reaction was completed, sodium hydroxide aqueous solution was added to adjust the pH to 6.0 to obtain an ester-ether composite polycarboxylic acid-based high-efficiency water reducer.

[0040] Example 5

[0041] 0.5 kg of allyl alcohol as a reaction raw material was added to a pressure reaction vessel, and 0.08 kg of metallic sodium alcoholate was added as a catalyst. Mechanical stirring was performed under the reaction condition of 135°C, and the pressure of the reaction device was 2.3 MPa. 5 kg of 3,4-epoxyhexane methyl ester was added to carry out anionic ring-opening polymerization, and the reaction time was 5 hours. After the reaction was completed, the pH was adjusted to 10, and the reaction obtained unsaturated polyoxyethylene ether A1 containing both ester bonds and ether bonds.

[0042] 0.8 kg of isopentenol as a reaction raw material was added to a pressure reaction vessel, and 0.15 kg of metal sodium alcoholate was added as a catalyst. Mechanical stirring was performed under the reaction condition of 140°C, and the pressure of the reaction device was 2.9 MPa. 6 kg of 3,4-epoxyhexane ethyl ester was added for anionic ring-opening polymerization, and the reaction time was 3.5 hours. After the reaction was completed, the pH was adjusted to 8.5, and the reaction obtained an unsaturated polyoxyethylene ether A4 containing both ester bonds and ether bonds.

[0043] Step 2:

[0044] 0.7 kg of acrylic acid was added to the reaction device, and 5 kg of unsaturated polyoxyethylene ether A1 and 5.5 kg of unsaturated polyoxyethylene ether A4 were added under mechanical stirring conditions. The reaction temperature was controlled to be 30°C, and 0.18 kg of hydrogen peroxide and 0.07 kg of vitamin C were added as initiators for free radical copolymerization. The reaction time was 180 min. After the reaction was completed, sodium hydroxide aqueous solution was added to adjust the pH to 6.0 to obtain an ester-ether composite polycarboxylic acid-based high-efficiency water reducer.

[0045] Concrete admixtures were synthesized using the technical solutions of Examples 1-5, and the effects of such concrete admixtures on the initial performance and time-dependent performance of cement mortar were measured. The detection method was based on GB / T 8077-2012 concrete admixture homogeneity test method, and the unit of fluidity expansion diameter was millimeter (mm). The experimental results are shown in Table 1 below:

[0046] Table 1

[0047]

[0048]

[0049] The building sand was washed to remove the soil, and then dried to remove the moisture. Then 1%, 3% and 5% of the soil component were added to it respectively, and mixed evenly. The expansion degree after 60 minutes was measured by the glue sand test. The results are shown in Table 2:

[0050] Table 2

[0051]

[0052] It can be seen that the polycarboxylic acid-based high-efficiency water reducer of the present invention has both ester and ether functional groups, and the ratio of the two functional groups is close to 1:1, so they can play a synergistic role. Compared with the ester-ether copolymer polycarboxylic acid water reducer of the prior art, the ester functional groups and ether functional groups of the polymerization product of the present invention are evenly distributed, avoiding the random distribution of the two functional groups in the prior art. Therefore, the molecular structure uniformity of the synthesized polycarboxylic acid water reducer is higher, and it has better slow setting and slump retention performance and mud resistance performance.

[0053] The above description is only a preferred embodiment of the present invention, and does not limit the implementation mode and protection scope of the present invention. For those skilled in the art, it should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the contents of the specification of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing an ester-ether composite polycarboxylate water-reducing agent, characterized in that: The steps include: Step 1, using an unsaturated enol compound as a reaction raw material, adding an alkali metal alcoholate as a catalyst, and carrying out an anionic ring-opening polymerization reaction with 3,4-epoxyhexane ester, and adjusting the pH to 8-12 after the reaction is completed to obtain an unsaturated polyoxyethylene ether containing both ester bonds and ether bonds; Step 2, the unsaturated polyoxyethylene ether prepared in step 1 is subjected to a free radical copolymerization reaction with an unsaturated carboxylic acid compound, and after the reaction is completed, the pH is adjusted to 5.0-6.5 to obtain an ester-ether composite polycarboxylic acid-based high-efficiency water reducer; Wherein, the 3,4-epoxyhexane ester is 3,4-epoxyhexane methyl ester or 3,4-epoxyhexane ethyl ester or a mixture of the two.

2. The method for preparing the ester-ether composite polycarboxylate water-reducing agent according to claim 1, characterized in that: In the step 1, the reaction temperature of the anionic ring-opening polymerization reaction is 120-145° C., the reaction time is 3-7 hours, and the pressure of the reaction device is 1.7-3.8 MPa.

3. The method for preparing the ester-ether composite polycarboxylate water-reducing agent according to claim 1, characterized in that: In the step 1, the amount of the catalyst used is 0.7-2.5% of the total amount of the reactants, and the molar ratio of the unsaturated enolate compound to the 3,4-epoxyhexane ester is 1:(8-25).

4. The method for preparing the ester-ether composite polycarboxylate water-reducing agent according to claim 1, characterized in that: In the step 2, the unsaturated carboxylic acid compound is acrylic acid or methacrylic acid or a mixture of the two.

5. The method for preparing the ester-ether composite polycarboxylate water-reducing agent according to claim 1, characterized in that: In the step 2, the molar ratio of the unsaturated polyoxyethylene ether to the unsaturated carboxylic acid compound is 1:(2.5-5.5).

6. The method for preparing the ester-ether composite polycarboxylate water-reducing agent according to claim 1, characterized in that: In the step 2, the initiators used are hydrogen peroxide and vitamin C, wherein the mass ratio of hydrogen peroxide to vitamin C is 1:(0.2-0.5), and the total amount of the initiator is 0.5-2.5% of the total mass of the reactants.

7. The method for preparing the ester-ether composite polycarboxylate water-reducing agent according to claim 1, characterized in that: In the step 2, the reaction temperature of the free radical copolymerization reaction is 15-35° C., and the reaction time is 90-360 min.

8. An ester-ether composite polycarboxylate water-reducing agent prepared by the preparation method according to any one of claims 1 to 7.

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