阅读说明：本技术 一种聚羧酸高性能减水剂及其制备方法 (Polycarboxylic acid high-performance water reducing agent and preparation method thereof ) 是由 潘全世 薛兆和 于 2019-09-10 设计创作，主要内容包括：本发明涉及一种聚羧酸高性能减水剂及其制备方法,属于减水剂技术领域,减水剂的原料包括甲氧基聚乙二醇甲基丙烯酸酯、初引发剂、反应引发剂、乙醇、丙烯酸、丙烯酸羟乙酯、氯乙烯、二甲胺基丙基甲基丙烯酰胺、巯基丙酸、釜底水、软化水。该聚羧酸高性能减水剂,通过原料之间的协同作用,使其不仅能够降低混凝土坍落度1h经时变化量,而且还使混凝土具有较高减水率、较高抗压强度的优点,采用分步骤的进行原料混合和反应,不仅使减水剂的制备方法简单、便于控制,而且提高了减水剂生产的稳定性。(The invention relates to a polycarboxylic acid high-performance water reducing agent and a preparation method thereof, belonging to the technical field of water reducing agents. The polycarboxylic acid high-performance water reducer not only can reduce the 1h time-varying amount of concrete slump through the synergistic effect between the raw materials, but also enables the concrete to have the advantages of higher water reducing rate and higher compressive strength.)

1. A polycarboxylic acid high-performance water reducing agent is characterized in that: the water reducing agent comprises, by weight, 3000-6500 parts of methoxy polyethylene glycol methacrylate, 2-10 parts of an initial initiator, 30-40 parts of a reaction initiator, 1-5 parts of ethanol, 300 parts of acrylic acid, 400 parts of hydroxyethyl acrylate, 0.8-8 parts of vinyl chloride, 70-100 parts of dimethylaminopropyl methacrylamide, 1-12 parts of mercaptopropionic acid, 2000 parts of still bottom water and 2000 parts of softened water, and the water reducing agent has a structural general formula as follows:

wherein a, b, c, d, e and m are the number of the repeating unit chain links of the water reducing agent, and the average molecular weight of the water reducing agent is 80-130 ten thousand.

2. The polycarboxylic acid high-performance water reducing agent according to claim 1, characterized in that: the raw materials comprise 3600-4800 parts of methoxy polyethylene glycol methacrylate, 5-7 parts of an initial initiator, 33-37 parts of a reaction initiator, 2-4 parts of ethanol, 150-250 parts of acrylic acid, 430 parts of hydroxyethyl acrylate, 3-8 parts of vinyl chloride, 80-100 parts of dimethylaminopropyl methacrylamide, 4-8 parts of mercaptopropionic acid, 1300 parts of kettle bottom water, 1700 parts of softened water and 1600 parts of ethylene glycol methacrylate.

3. The polycarboxylic acid high-performance water reducing agent according to claim 1, characterized in that: the weight ratio of the methoxy polyethylene glycol methacrylate to the acrylic acid to the hydroxyethyl acrylate is 50:2: 4.4.

4. The polycarboxylic acid high-performance water reducing agent according to claim 1, characterized in that: the initial initiator is hydrogen peroxide solution with the weight fraction of 10-15%, and the initial initiator is hydrogen peroxide solution with the weight fraction of 3-8%.

5. The polycarboxylic acid high-performance water reducing agent according to claim 1, characterized in that: the pH value of the water reducing agent is 5-6.

6. A method for preparing a polycarboxylic acid high performance water reducing agent according to any one of claims 1 to 5, characterized in that: the method comprises the following steps:

(1) dividing softened water into three parts, namely softened water A, softened water B and softened water C;

(2) adding acrylic acid and hydroxyethyl acrylate into the softened water A, and uniformly mixing to obtain a mixture A for later use;

(3) adding chloroethylene, dimethylamino propyl methacrylamide and mercaptopropionic acid into the softened water B, and uniformly mixing to obtain a mixture B for later use;

(4) under the protection of inert gas, heating kettle bottom water, adding ethanol and methoxy polyethylene glycol methacrylate, uniformly mixing, continuously heating, adding a primary initiator when the temperature reaches 60 ℃, stirring for 5-10min, then respectively dropwise adding the mixture A, the mixture B and a reaction initiator in a dropwise adding mode, wherein the dropwise adding time of the mixture A is 2-2.3h, the dropwise adding time of the mixture B is 2.5-2.8h, the dropwise adding time of the reaction initiator is 2.6-2.9h, the temperature is controlled to be 60-65 ℃, and carrying out heat preservation reaction for 2-4 h;

(5) and cooling to 50 ℃, adding softened water C, uniformly mixing, cooling to room temperature, and filtering to obtain the water reducer.

7. The method for preparing the polycarboxylic acid high-performance water reducing agent according to claim 6, characterized by comprising the following steps: the weight ratio of the softened water A to the softened water B to the softened water C is 3:3: 2.

8. The method for preparing the polycarboxylic acid high-performance water reducing agent according to claim 6, characterized by comprising the following steps: the pH value of the water reducing agent is adjusted by adopting a sodium hydroxide solution with the weight percentage of 5%.

9. The method for preparing the polycarboxylic acid high-performance water reducing agent according to claim 6, characterized by comprising the following steps: the mixture A, the mixture B, the primary initiator and the reaction initiator are prepared in situ and are prepared within 3min before use.

Technical Field

The invention relates to the technical field of water reducing agents, in particular to a polycarboxylic acid high-performance water reducing agent and a preparation method thereof.

Background

The water reducing agent is a concrete admixture capable of reducing the water consumption for mixing, has become an indispensable component of concrete due to the advantages of dispersing cement particles and reducing unit water consumption after being added into the concrete, and plays an increasingly important role in improving the performance of the concrete. The water reducing agent can be divided into lignosulfonic acid series, naphthalene series, melamine series, sulfamic acid series, polycarboxylic acid series and the like according to varieties, and the polycarboxylic acid series water reducing agent is a chemically synthesized polycarboxylic acid comb graft copolymer which can be adsorbed on the surface of cement particles, so that the cement particles have high dispersibility and fluidity retentivity through electrostatic repulsion and steric hindrance effects.

When constructing the concrete, the concrete is from mix to the process of pouring, inevitable needs are parked, transit time, always can be along with the change of concrete slump at this in-process, especially to the higher concrete construction of pumping floor, if the loss of slump is too fast, bring the difficulty for the construction, and the water-reducing agent has certain influence to the change of concrete slump, consequently, also provide higher requirement to polycarboxylate water-reducing agent, and need study one kind can reduce the water-reducing agent of concrete slump over-the-time variation, in order to satisfy the market demand.

Disclosure of Invention

The invention aims to provide a polycarboxylic acid high-performance water reducing agent which can reduce the change of concrete slump for 1h with time and also has the advantages of higher water reducing rate and higher compressive strength.

The technical purpose of the invention is realized by the following technical scheme:

a polycarboxylic acid high-performance water reducing agent is characterized in that: the water reducing agent comprises, by weight, 3000-6500 parts of methoxy polyethylene glycol methacrylate, 2-10 parts of an initial initiator, 30-40 parts of a reaction initiator, 1-5 parts of ethanol, 300 parts of acrylic acid, 400 parts of hydroxyethyl acrylate, 0.8-8 parts of vinyl chloride, 70-100 parts of dimethylaminopropyl methacrylamide, 1-12 parts of mercaptopropionic acid, 2000 parts of still bottom water and 2000 parts of softened water, and the water reducing agent has a structural general formula as follows:

wherein a, b, c, d, e and m are the number of the repeating unit chain links of the water reducing agent, and the average molecular weight of the water reducing agent is 80-130 ten thousand.

By adopting the technical scheme, free radical polymerization reaction is carried out among methoxy polyethylene glycol methacrylate, acrylic acid, hydroxyethyl acrylate, vinyl chloride and dimethylamino propyl methacrylamide, a macromolecular copolymer is formed, the water reducing agent is adsorbed on the surface of cement particles, a double electric layer is formed, electrostatic repulsion force is formed among the cement particles, the flocculation structure of the cement particles is damaged, the cement particles are mutually dispersed, free water is released, the fluidity of cement paste is increased, the water reducing rate of concrete is increased, the water reducing agent is a comb graft copolymer and has longer side chains, the cement particles generate larger steric hindrance under the action of the long side chains, the agglomeration among the cement particles is effectively prevented, the fluidity of the cement paste can be improved through the synergistic effect among raw materials, and the 1h time-varying amount of the concrete is reduced, namely, the slump loss of the concrete is reduced, and meanwhile, the concrete has the advantages of higher water reducing rate and higher compressive strength.

More preferably, the raw materials comprise 3600-4800 parts of methoxy polyethylene glycol methacrylate, 5-7 parts of an initial initiator, 33-37 parts of a reaction initiator, 2-4 parts of ethanol, 150-250 parts of acrylic acid, 140-430 parts of hydroxyethyl acrylate, 3-8 parts of vinyl chloride, 80-100 parts of dimethylaminopropyl methacrylamide, 4-8 parts of mercaptopropionic acid, 1300-1700 parts of bottom water and 500-1600 parts of softened water.

More preferably, the weight ratio of the methoxypolyethylene glycol methacrylate to the acrylic acid to the hydroxyethyl acrylate is 50:2: 4.4.

By adopting the technical scheme, the raw material ratio of the water reducing agent is optimized, and the weight ratio of the methoxy polyethylene glycol methacrylate, the acrylic acid and the hydroxyethyl acrylate is optimized, so that the using effect of the water reducing agent is improved, and the water reducing rate and the compressive strength of the concrete are further improved.

More preferably, the initial initiator is 10-15% of hydrogen peroxide solution by weight, and the initial initiator is 3-8% of hydrogen peroxide solution by weight.

By adopting the technical scheme, the primary initiator and the reaction initiator can generate hydroxyl free radicals in the raw materials, the hydroxyl free radicals promote the free radical polymerization reaction between the raw materials and enable the raw materials to form a macromolecular copolymer, the primary initiator accelerates the efficiency of the initial reaction of the raw materials, and the reaction initiator enables the concentration of the hydroxyl free radicals in the raw materials to be kept constant, so that the efficiency of the free radical polymerization reaction of the raw materials is maintained, and the production efficiency of the water reducing agent is improved through the synergistic effect between the primary initiator and the reaction initiator.

More preferably, the pH value of the water reducing agent is 5-6.

By adopting the technical scheme, the water reducing agent is weakly acidic, so that the storage container of the water reducing agent is prevented from being corroded due to high acidity of the water reducing agent, the storage time is shortened due to low acidity of the water reducing agent, the pH value of the water reducing agent is 5-6, and the storage effect of the water reducing agent is improved.

The second purpose of the invention is to provide a method for preparing the polycarboxylic acid high-performance water reducing agent, which not only ensures that the preparation method of the water reducing agent is simple and convenient to control, but also improves the production stability of the water reducing agent.

The technical purpose of the invention is realized by the following technical scheme:

a method for preparing the polycarboxylic acid high-performance water reducing agent comprises the following steps: the method comprises the following steps:

(1) dividing softened water into three parts, namely softened water A, softened water B and softened water C;

(2) adding acrylic acid and hydroxyethyl acrylate into the softened water A, and uniformly mixing to obtain a mixture A for later use;

(3) adding chloroethylene, dimethylamino propyl methacrylamide and mercaptopropionic acid into the softened water B, and uniformly mixing to obtain a mixture B for later use;

(4) under the protection of inert gas, heating kettle bottom water, adding ethanol and methoxy polyethylene glycol methacrylate, uniformly mixing, continuously heating, adding a primary initiator when the temperature reaches 60 ℃, stirring for 5-10min, then respectively dropwise adding the mixture A, the mixture B and a reaction initiator in a dropwise adding mode, wherein the dropwise adding time of the mixture A is 2-2.3h, the dropwise adding time of the mixture B is 2.5-2.8h, the dropwise adding time of the reaction initiator is 2.6-2.9h, the temperature is controlled to be 60-65 ℃, and carrying out heat preservation reaction for 2-4 h;

(5) and cooling to 50 ℃, adding softened water C, uniformly mixing, cooling to room temperature, and filtering to obtain the water reducer.

By adopting the technical scheme, softened water is divided into three parts, so that the preparation of the mixture A and the mixture B is convenient, the control of the concentration of the water reducer is convenient, the acrylic acid and the hydroxyethyl acrylate are prepared into the mixture A, the vinyl chloride, the dimethylamino propyl methacrylamide and the mercaptopropionic acid are prepared into the mixture B, the preparation of the mixture A and the mixture B is convenient, the reaction between the mixture A and the mixture B is reduced, meanwhile, the ethanol is added into the methoxy polyethylene glycol methacrylate, part of the ethanol volatilizes due to heat absorption, a protective layer is formed above the water at the bottom of the kettle, part of the ethanol is remained in the water at the bottom of the kettle, the mixing uniformity among the raw materials is increased, after the dropwise addition of the mixture A and the mixture B is finished, the reaction initiator is continuously dropwise added, and the production stability of the water reducer is.

More preferably, the weight ratio of the softened water A to the softened water B to the softened water C is 3:3: 2.

By adopting the technical scheme, the softened water A is used for preparing the mixture A, the softened water B is used for preparing the mixture B, the softened water C is used for controlling the concentration of the water reducing agent, and the proportion of the softened water A, the softened water B and the softened water C is limited, so that the preparation of the water reducing agent is controlled conveniently, and the production of the water reducing agent is more stable.

More preferably, the water reducing agent adopts 5% by weight of sodium hydroxide solution to adjust the pH value.

By adopting the technical scheme, the pH value of the water reducing agent is adjusted, the raw material of sodium hydroxide is easy to obtain, and the production cost of the water reducing agent is reduced.

Preferably, the mixture A, the mixture B, the primary initiator and the reaction initiator are prepared in situ and within 3min before use.

By adopting the technical scheme, after the mixture A and the mixture B are prepared, firstly, the raw materials are easily oxidized and deteriorated due to the existence of oxygen, partial polymerization can also occur between the raw materials, a small amount of hydroxyl free radicals are immediately generated in the initial initiator and the reaction initiator after the preparation is completed, the hydroxyl free radicals move freely and are easily collided and eliminated, the preparation completion time of the mixture A, the mixture B, the initial initiator and the reaction initiator is limited, and the influence on the performance and the production stability of the water reducing agent due to deterioration is reduced.

In conclusion, the invention has the following beneficial effects:

firstly, the polycarboxylic acid high-performance water reducing agent disclosed by the invention can reduce the change of the concrete slump for 1h with the time, and also has the advantages of higher water reducing rate and higher compressive strength.

And secondly, limiting the primary initiator and the reaction initiator, and improving the production efficiency of the water reducer through the synergistic effect of the primary initiator and the reaction initiator.

Thirdly, the method for preparing the polycarboxylic acid high-performance water reducing agent not only ensures that the preparation method of the water reducing agent is simple and convenient to control, but also improves the production stability of the water reducing agent.

And fourthly, the time for finishing the preparation of the mixture A, the mixture B, the primary initiator and the reaction initiator is limited, so that the influence on the performance and the production stability of the water reducer caused by deterioration is reduced.

Detailed Description

The present invention will be described in further detail with reference to examples. It should be understood that the preparation methods described in the examples are only for illustrating the present invention and are not to be construed as limiting the present invention, and that the simple modifications of the preparation methods of the present invention based on the concept of the present invention are within the scope of the present invention as claimed.

The structural general formula of the water reducing agent is as follows:

wherein a, b, c, d, e and m are the number of repeating unit links of the water reducing agent, and m is an integer of 23 to 35, preferably 25.

Table 1 examples the water reducing agent contained in each raw material (unit: Kg)