Hydrophobic modified unsaturated polyether for polycarboxylate superplasticizer and preparation method of hydrophobic modified unsaturated polyether

Abstract

The invention discloses hydrophobic modified unsaturated polyether for a polycarboxylic acid water reducer and a preparation method thereof, and the preparation method comprises the following steps: mixing vinylphenol substances, an organic amine catalyst and a polymerization inhibitor, under the protection of inert gas, heating to 60-90 DEG C, introducing ethylene oxide gas, and then curing for 10-60 minutes; cooling to 40 DEG C or below, adding a catalyst, heating to 100-130 DEG C under the protection of inert gas, continuously introducing ethylene oxide gas, and then curing for 10-60 minutes; adjusting the pH value of the reaction system to 7-9; unsaturated double bonds in the hydrophobic modified unsaturated polyether are connected with a benzene ring, compared with EPEG polyether, the charge environment of the double bonds is greatly improved, the activity of the double bonds is improved, the dropwise adding time of acrylic acid during synthesis of the polycarboxylate superplasticizer can be greatly shortened, the hydrophobicity of the benzene ring is high, the HLB value of the polyether can be reduced, and the hydrophobic property of the polyether is improved. Therefore, the viscosity of the concrete is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of water reducers, and particularly relates to a hydrophobically modified unsaturated polyether for a polycarboxylic acid water reducer and a preparation method thereof. Background Art

[0002] Polyethers for polycarboxylic acids are usually made by the addition polymerization of unsaturated enols, such as allyl alcohol, methyl allyl alcohol, isopentanol, diethylene glycol monovinyl ether and ethylene glycol monovinyl ether, with ethylene oxide. The mainstream types of polyethers for polycarboxylic acids are methyl allyl alcohol polyoxyethylene ether (HPEG), isopentanol polyoxyethylene ether (TPEG) and ethylene glycol monovinyl polyoxyethylene ether (EPEG). The unsaturated double bonds in HPEG and TPEG polyethers are connected to two carbon atoms, and the unsaturated double bonds in EPEG are directly connected to an oxygen atom, forming a molecular structure with a group of CO bonds. This change in molecular structure shifts the distribution of the double bond electron cloud, thereby improving the charge environment of the unsaturated double bonds in the macromonomer, making the reactivity of the double bonds in the EPEG macromonomer much greater than that of general macromonomers (HPEG and TPEG), making it easier to undergo polymerization reactions.

[0003] Although the performance of EPEG is significantly better than that of HPEG and TPEG, and the synthesized polycarboxylic acid water-reducing agent has higher adaptability, especially for the conditions of poor quality of sand and gravel and high mud content, it cannot effectively solve the problem of high concrete viscosity caused by low water-cement ratio.

[0004] Currently, the viscosity of concrete is mainly reduced by grafting some hydrophobic functional groups into the polycarboxylic acid mother liquor or reducing the molecular weight of the polyether. However, both methods will have a certain impact on the water reduction or slump retention performance of the mother liquor, and there are problems such as complex grafting modification process, low water reduction of the mother liquor, and large dosage. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a hydrophobically modified unsaturated polyether for polycarboxylate water-reducing agent and a preparation method thereof. In the hydrophobically modified unsaturated polyether for polycarboxylate water-reducing agent, the unsaturated double bond is connected to the benzene ring. Compared with EPEG polyether, it not only greatly improves the charge environment of the double bond, but also further improves the activity of the double bond, and can greatly reduce the dripping time of acrylic acid during the synthesis of polycarboxylate water-reducing agent, and the benzene ring has high hydrophobicity, which can reduce the HLB value of the polyether, thereby reducing the viscosity of the concrete.

[0006] The present invention also provides a polycarboxylate water reducer and a preparation method thereof, which is prepared using the hydrophobically modified unsaturated polyether of the present invention as a raw material. The polycarboxylate water reducer can significantly reduce the viscosity of concrete.

[0007] The technical solution adopted by the present invention is as follows:

[0008] A method for preparing a hydrophobically modified unsaturated polyether for a polycarboxylate water-reducing agent, the method comprising the following steps:

[0009] (1) mixing vinyl phenol, organic amine catalyst and polymerization inhibitor, heating to 60-90° C. under the protection of inert gas, introducing ethylene oxide gas, and then aging for 10-60 min;

[0010] (2) Cooling to below 40°C, adding a catalyst, heating to 100-130°C under the protection of an inert gas, continuing to introduce ethylene oxide gas, and then aging for 10-60 minutes;

[0011] (3) adjusting the pH of the reaction system to 7-9 to obtain a hydrophobically modified unsaturated polyether for a polycarboxylic acid water-reducing agent.

[0012] In step (1), the vinylphenol substance is one of 4-vinylphenol, 3-vinylphenol, 2-vinylphenol and 2-methoxy-4-vinylphenol.

[0013] The organic amine catalyst is at least one of N,N-dimethylethylamine, N,N-diethylmethylamine and triethylamine; the mass of the organic amine catalyst is 0.1-0.5% of the mass of the vinyl phenol substance.

[0014] In step (1), the polymerization inhibitor is at least one of nitroxyl piperidinol, methyl hydroquinone, 2,2-biphenyl-1-picrylhydrazyl, and p-tert-butylcatechol; and the mass of the polymerization inhibitor is 1-3% of the mass of the vinyl phenol substance.

[0015] In step (2), the catalyst is one of sodium, sodium hydroxide, potassium hydroxide, sodium hydride, and sodium methoxide; the mass of the catalyst is 1-2% of the mass of the vinyl phenol substance.

[0016] The mass ratio of the vinyl phenol substance to ethylene oxide is 1:15-30; the mass ratio of the ethylene oxide introduced in step (1) to the ethylene oxide introduced in step (2) is 1:8-15.

[0017] In step (3), acetic acid is used to adjust the pH of the reaction system to 7-9.

[0018] The present invention also provides a hydrophobically modified unsaturated polyether for a polycarboxylate water-reducing agent prepared by the preparation method.

[0019] The present invention also provides a polycarboxylic acid water reducer, which uses the hydrophobically modified unsaturated polyether of the present invention as a raw material.

[0020] The present invention also provides a method for preparing a polycarboxylate water reducer, which is prepared by using the hydrophobically modified unsaturated polyether of the present invention as a raw material.

[0021] The preparation method specifically comprises the following steps: mixing a hydrophobically modified unsaturated polyether, water and hydrogen peroxide to form a base liquid, mixing acrylic acid, mercaptopropionic acid and water to form a drop liquid A, and mixing sodium formaldehyde sulfoxylate and water to form a drop liquid B, wherein the initial temperature of the base liquid is 3-8°C, stirring is started, and materials A and B are added dropwise at the same time, and after the addition is completed, the liquid is matured and the temperature is controlled below 25°C.

[0022] Furthermore, the dropping time is 0.5 h, and the aging time is 0.5 h.

[0023] In the preparation method of the hydrophobically modified unsaturated polyether for polycarboxylic acid water-reducing agent provided by the present invention, a low-temperature catalyst is used in the early stage to carry out low-temperature polymerization with the assistance of a polymerization inhibitor to prepare a low molecular weight polyether and reduce the double bond activity; and then high-temperature polymerization is carried out to prepare a high molecular weight polyether. This is because the double bond activity of vinyl phenol substances is high due to the presence of benzene rings. If one of sodium, sodium hydroxide, potassium hydroxide, sodium hydride, and sodium methoxide is directly used as a catalyst, at a high temperature of 100-130°C, the vinyl phenol substances will self-polymerize, resulting in a low synthesis yield of the hydrophobically modified unsaturated polyether.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] In the hydrophobically modified unsaturated polyether for polycarboxylate water-reducing agent provided by the present invention, the unsaturated double bond is connected to the benzene ring, and compared with EPEG polyether, the hydrophobically modified unsaturated polyether not only greatly improves the charge environment of the double bond, but also further improves the activity of the double bond; when the hydrophobically modified unsaturated polyether is used as a raw material of the polycarboxylate water-reducing agent to prepare the polycarboxylate water-reducing agent, the dripping time of acrylic acid during the synthesis of the polycarboxylate water-reducing agent can be greatly reduced, and the preparation time of the polycarboxylate water-reducing agent can be controlled within 1 hour; and the hydrophobicity of the benzene ring is high, and when the polycarboxylate water-reducing agent is used as an additive for cement or concrete, the viscosity of the cement or concrete can be significantly reduced, the emptying time of the cement or concrete can be greatly increased, and the construction performance of the concrete can be improved. DETAILED DESCRIPTION

[0026] The present invention is described in detail below with reference to the embodiments.

[0027] The parts mentioned in the embodiments and comparative examples are all parts by weight.

[0028] Implementation 1

[0029] A method for preparing a hydrophobically modified unsaturated polyether for a polycarboxylate water-reducing agent comprises the following steps:

[0030] 1 part of 4-vinylphenol, 0.001 part of triethylamine and 0.01 part of nitroxyl piperidinol were put into a reaction kettle, replaced with nitrogen, the air in the reaction kettle was discharged, the temperature was raised to 60°C, 1.5 parts of ethylene oxide were introduced, the reaction pressure was controlled at 0.2MPa, and after the ethylene oxide was introduced, it was aged for 10 minutes;

[0031] The temperature of the reactor was lowered to 20°C, 0.016 parts of metallic sodium was added, the reactor was closed, the atmosphere was replaced with nitrogen again, the air in the reactor was discharged, the temperature was raised to 100°C, 15.1 parts of ethylene oxide were added, and after aging for 20 minutes, acetic acid was added to neutralize the pH of the reaction system to 7, and a hydrophobically modified unsaturated polyether with a molecular weight of Mn = 2000 ± 30 was obtained. The hydroxyl value was 27.83 mg / g and the double bond retention rate was 94.45%.

[0032] The molecular weight of the hydrophobically modified unsaturated polyether is determined by the hydroxyl value, and the loss of double bonds is determined by the double bond retention rate, in accordance with "Polyether and Its Derivatives for Concrete Admixtures" (JC / T2033-2018).

[0033] Implementation 2

[0034] A method for preparing a hydrophobically modified unsaturated polyether for a polycarboxylate water-reducing agent comprises the following steps:

[0035] 1 part of 3-vinylphenol, 0.003 parts of N,N-dimethylethylamine and 0.02 parts of p-tert-butylcatechol were put into a reaction kettle, replaced with nitrogen, the air in the reaction kettle was discharged, the temperature was raised to 80°C, 2.5 parts of ethylene oxide were introduced, and the reaction pressure was controlled at 0.5MPa. After the ethylene oxide was introduced, it was aged for 30 minutes;

[0036] The temperature of the reactor was lowered to 40°C, 0.013 parts of sodium methoxide were added, the reactor was closed, the gas was replaced with nitrogen again, the air in the reactor was discharged, the temperature was raised to 130°C, 22.8 parts of ethylene oxide were added, and after aging for 30 minutes, acetic acid was added to neutralize the pH of the reaction system to 9, and a hydrophobically modified unsaturated polyether with a molecular weight of Mn = 3000 ± 3 was obtained. The hydroxyl value was 18.56 mg / g and the double bond retention rate was 93.32% Example 3

[0037] A method for preparing a hydrophobically modified unsaturated polyether for a polycarboxylate water-reducing agent comprises the following steps:

[0038] 1 part of 2-vinylphenol, 0.005 parts of N,N-diethylmethylamine and 0.03 parts of 2,2-biphenyl-1-picrylhydrazyl were added into a reaction kettle, replaced with nitrogen, the air in the reaction kettle was discharged, the temperature was raised to 70°C, 2.0 parts of ethylene oxide were introduced, the reaction pressure was controlled at 0.3MPa, and after the ethylene oxide was introduced, it was aged for 50min;

[0039] The temperature of the reactor was lowered to 30°C, 0.02 parts of potassium hydroxide was added, the reactor was closed, the gas was replaced with nitrogen again, the air in the reactor was discharged, the temperature was raised to 110°C, 27.2 parts of ethylene oxide were added, and after aging for 50 minutes, acetic acid was added to neutralize the pH of the reaction system to 8, and a hydrophobically modified unsaturated polyether with a molecular weight of Mn = 3500 ± 30 was obtained. The hydroxyl value was 16.07 mg / g and the double bond retention rate was 92.22% Example 4

[0040] A method for preparing a hydrophobically modified unsaturated polyether for a polycarboxylate water-reducing agent comprises the following steps:

[0041] 1 part of 2-methoxy-4-vinylphenol, 0.004 part of triethylamine and 0.03 part of methylhydroquinone were put into a reaction kettle, replaced with nitrogen, the air in the reaction kettle was discharged, the temperature was raised to 90°C, 1.5 parts of ethylene oxide were introduced, the reaction pressure was controlled at 0.4MPa, and after the ethylene oxide was introduced, it was aged for 30 minutes;

[0042] The temperature of the reactor was lowered to 25°C, 0.02 parts of sodium hydride were added, the reactor was closed, the gas was replaced with nitrogen again, the air in the reactor was discharged, the temperature was raised to 120°C, 15.4 parts of ethylene oxide were added, and after aging for 40 minutes, acetic acid was added to neutralize the pH of the reaction system to 9 to obtain a hydrophobically modified unsaturated polyether with a molecular weight of Mn=2500±30. The hydroxyl value was 22.59 mg / g after chemical analysis, and the double bond retention rate was 93.14%.

[0043] Comparative Example 1

[0044] 1 part of 2-methoxy-4-vinylphenol, 0.024 parts of sodium hydride and 0.03 parts of methylhydroquinone were put into a reaction kettle, replaced with nitrogen, the air in the reaction kettle was discharged, the temperature was raised to 120°C, 16.9 parts of ethylene oxide were introduced, the reaction pressure was controlled at 0.4MPa, after the ethylene oxide was introduced, the reaction was aged for 50min, acetic acid was added to neutralize the pH of the reaction system to 9, and the obtained product was chemically analyzed and determined, the hydroxyl value was 26.13mg / g; the double bond retention rate was 34.67%, which shows that the double bonds were partially ring-opened and polymerized at high temperature, the double bond retention rate of the prepared material was low, and the material was viscous and the epoxy polymerization degree was low.

[0045] Application Examples 1-4

[0046] 44.3 parts of the hydrophobically modified unsaturated polyether prepared in Example 1-4, 37.68 parts of water and 0.17 parts of hydrogen peroxide with a mass concentration of 27.5% were prepared into a base liquid, 4.69 parts of acrylic acid, 0.2 parts of mercaptopropionic acid and 4.69 parts of water were prepared into material A, 0.06 parts of sodium formaldehyde sulfoxylate and 4.06 parts of water were prepared into material B, the initial temperature of the base liquid was 5°C, stirring was started, material A and material B were added dropwise at the same time, the dropping time was 0.5h, after the dropping was completed, it was matured for 0.5h, and the temperature was controlled below 25°C to obtain polycarboxylic acid water reducer 1-4 synthesized using the hydrophobically modified unsaturated polyether in Example 1-4.

[0047] Application Comparative Example 1

[0048] The rest is the same as in Application Examples 1-4, except that the hydrophobically modified unsaturated polyether is replaced by an equal amount of EPEG polyether with a molecular weight of 3000.

[0049] Application Comparative Example 2

[0050] The other steps are the same as those in Comparative Example 1, except that the addition time of material A and material B is 1 hour, and the material is ripened for 1 hour after the addition is completed.

[0051] Test Case

[0052] The polycarboxylate water-reducing agents prepared in the above-mentioned application examples and application comparative examples were used as additives for cement and concrete, respectively. Then, the fluidity of cement paste was tested according to the standard "Polycarboxylate High Performance Water-Reducing Agent" (JC / T 223-2007), the viscosity of cement paste was tested according to the "Method for Determination of Viscosity of Cement Paste" (GB / T 43876-2024), and the slump or expansion of concrete and the emptying time of concrete were tested according to the "Standard for Test Methods for Performance of Ordinary Concrete Mixtures" (GB / T 50080-2016). The results are shown in Tables 1 and 2.

[0053] Table 1

[0054]

[0055] Table 2

[0056]

[0057] It can be seen from Table 1 and Table 2 that the water reducing agent synthesized by the hydrophobically modified unsaturated polyether prepared by the present invention under the same conditions has no obvious difference in water reducing performance from EPEG polyether through cement paste fluidity and concrete performance evaluation, but the viscosity of the concrete is significantly reduced. It can be seen that the polycarboxylate water reducing agent prepared by using the hydrophobically modified unsaturated polyether prepared by the preparation method provided by the present invention as the raw material of the polycarboxylate water reducing agent can significantly reduce the viscosity of concrete and improve the construction performance of concrete.

[0058] The above-mentioned detailed description of a hydrophobically modified unsaturated polyether for polycarboxylic acid water-reducing agent and its preparation method with reference to the embodiments is illustrative rather than restrictive, and several embodiments can be listed according to the limited scope. Therefore, changes and modifications without departing from the overall concept of the present invention should fall within the scope of protection of the present invention.

Claims

1. A method for preparing a hydrophobically modified unsaturated polyether for a polycarboxylate water-reducing agent, characterized in that: The preparation method comprises the following steps: (1) mixing vinyl phenol, organic amine catalyst and polymerization inhibitor, heating to 60-90° C. under the protection of inert gas, introducing ethylene oxide gas, and then aging for 10-60 min; (2) Cooling to below 40°C, adding a catalyst, heating to 100-130°C under the protection of an inert gas, continuing to introduce ethylene oxide gas, and then aging for 10-60 minutes; (3) adjusting the pH of the reaction system to 7-9 to obtain a hydrophobically modified unsaturated polyether for a polycarboxylic acid water-reducing agent.

2. The preparation method according to claim 1, characterized in that: In step (1), the vinylphenol substance is one of 4-vinylphenol, 3-vinylphenol, 2-vinylphenol and 2-methoxy-4-vinylphenol.

3. The preparation method according to claim 1, characterized in that: The organic amine catalyst is at least one of N,N-dimethylethylamine, N,N-diethylmethylamine and triethylamine; the mass of the organic amine catalyst is 0.1-0.5% of the mass of the vinyl phenol substance.

4. The preparation method according to claim 1, characterized in that: In step (1), the polymerization inhibitor is at least one of nitroxyl piperidinol, methyl hydroquinone, 2,2-biphenyl-1-picrylhydrazyl, and p-tert-butylcatechol; and the mass of the polymerization inhibitor is 1-3% of the mass of the vinyl phenol substance.

5. The preparation method according to claim 1, characterized in that: In step (2), the catalyst is one of sodium, sodium hydroxide, potassium hydroxide, sodium hydride, and sodium methoxide; the mass of the catalyst is 1-2% of the mass of the vinyl phenol substance.

6. The preparation method according to claim 1, characterized in that: The mass ratio of the vinyl phenol substance to ethylene oxide is 1:15-30; the mass ratio of the ethylene oxide introduced in step (1) to the ethylene oxide introduced in step (2) is 1:8-15.

7. The preparation method according to any one of claims 1 to 5, characterized in that: In step (3), acetic acid is used to adjust the pH of the reaction system to 7-9.

8. The hydrophobically modified unsaturated polyether for polycarboxylate water-reducing agent prepared by the preparation method according to any one of claims 1 to 7.

9. A polycarboxylate water reducer, characterized in that: The hydrophobically modified unsaturated polyether described in claim 8 is used as a raw material.

10. The method for preparing a polycarboxylate water-reducing agent according to claim 9, characterized in that: The preparation method comprises the following steps: preparing with the hydrophobically modified unsaturated polyether as claimed in claim 8 as raw material.

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