阅读说明：本技术 一种固体聚羧酸减水剂及其制备方法 (Solid polycarboxylic acid water reducing agent and preparation method thereof ) 是由 朱建民 刘兆滨 董振鹏 杨雪 张建东 于 2020-05-13 设计创作，主要内容包括：本发明提供一种固体聚羧酸减水剂及其制备方法,该制备方法包括：将聚醚单体与超支化单体融化成液体；向所述液体中加入引发剂并搅拌,之后加入不饱和羧酸和链转移剂,得到混合溶液；以及对所述混合溶液进行老化处理,之后降温凝固,得到所述固体聚羧酸减水剂。本发明的固体聚羧酸减水剂由于加入了超支化单体,在聚合时对粘度的要求有所降低,并在混凝土评价过程中对混凝土和易性较好,无泌水、泌浆、漏石等现象,在低水灰比条件下能够降低混凝土粘度,此外,本发明的方法制备结束即得到无水固体聚羧酸减水剂产品,无需像传统母液水剂需经过喷雾干燥才能得到粉体聚羧酸减水剂,与粉体聚羧酸减水剂相比大大的减少了生产成本以及长途运输成本。(The invention provides a solid polycarboxylic acid water reducing agent and a preparation method thereof, wherein the preparation method comprises the following steps: melting polyether monomer and hyperbranched monomer into liquid; adding an initiator into the liquid, stirring, and then adding unsaturated carboxylic acid and a chain transfer agent to obtain a mixed solution; and carrying out aging treatment on the mixed solution, and then cooling and solidifying to obtain the solid polycarboxylic acid water reducing agent. The hyperbranched monomer is added into the solid polycarboxylate superplasticizer, so that the requirement on viscosity during polymerization is reduced, the concrete workability is better in the evaluation process of the concrete, the phenomena of bleeding, slurry bleeding, stone leakage and the like are avoided, the viscosity of the concrete can be reduced under the condition of low water-cement ratio, in addition, the anhydrous solid polycarboxylate superplasticizer product is obtained after the preparation of the method disclosed by the invention, the powder polycarboxylate superplasticizer can be obtained without spray drying like the traditional mother liquor water agent, and the production cost and the long-distance transportation cost are greatly reduced compared with the powder polycarboxylate superplasticizer.)

1. The preparation method of the solid polycarboxylic acid water reducing agent is characterized by comprising the following steps:

melting polyether monomer and hyperbranched monomer into liquid;

adding an initiator into the liquid, stirring, and then adding unsaturated carboxylic acid and a chain transfer agent to obtain a mixed solution; and

and carrying out aging treatment on the mixed solution, and then cooling and solidifying to obtain the solid polycarboxylic acid water reducing agent.

2. The preparation method according to claim 1, wherein the polyether monomer is added in an amount of 82 to 89% by mass, the hyperbranched monomer is added in an amount of 0.4 to 3% by mass, the unsaturated carboxylic acid is added in an amount of 7 to 11% by mass, the chain transfer agent is added in an amount of 0.2 to 0.7% by mass, and the initiator is added in an amount of 0.4 to 1.5% by mass, based on the total mass of the raw materials.

3. The preparation method as claimed in claim 1, wherein the polyether monomer is selected from one or more of methallyl polyoxyethylene ether, prenol polyoxyethylene ether and hydroxybutyl polyoxyethylene ether, and the molecular weight of the polyether monomer is 1200-5000, preferably 2000-4000.

4. The method according to claim 1, wherein the hyperbranched monomer has a structure represented by formula I, wherein n is an integer of 1 to 15, m is an integer of 1 to 10, x is an integer of 1 to 10, and y is an integer of 1 to 10.

5. The method of claim 1, wherein the initiator is selected from one or more of benzoyl peroxide, lauroyl peroxide, ammonium persulfate, potassium persulfate, sodium persulfate, azobisisobutyronitrile, azobisisoheptonitrile, azobisisovaleronitrile, azobisdicyclohexylcarbonitrile, azobisisobutyric acid dimethylku, dicyclohexyl peroxydicarbonate, and hexacosanyl peroxydicarbonate.

6. The method according to claim 1, wherein the unsaturated carboxylic acid is one or more selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, maleic anhydride, maleic acid, and fumaric acid.

7. The method of claim 1, wherein the chain transfer agent is selected from one or more of sodium methallyl sulfonate, sodium allyl sulfonate, thioglycolic acid, mercaptopropionic acid, mercaptoethanol, n-dodecylmercaptan, sodium hypophosphite, sodium vinyl sulfonate, sodium propenyl sulfonate, and sodium styrene sulfonate.

8. The production method according to claim 1, wherein the unsaturated carboxylic acid and the chain transfer agent are added to the liquid by a dropping method for 0.5 to 2 hours.

9. The method according to claim 1, wherein the aging treatment is carried out for 0.5 to 3 hours.

10. A solid polycarboxylic acid water reducing agent characterized in that it is prepared according to the method of any one of claims 1 to 9.

Technical Field

The invention relates to the field of concrete admixtures, and particularly relates to a solid polycarboxylic acid water reducing agent and a preparation method thereof.

Background

The water reducing agent is an indispensable important part in the current concrete industry, and from a first generation lignosulfonate series common water reducing agent to a second generation naphthalene series water reducing agent, a melamine series water reducing agent, a sulfamate series water reducing agent, a fatty acid series water reducing agent and other high-efficiency water reducing agents and to a third generation polycarboxylic acid series high-performance water reducing agent, each water reducing agent has the unique advantages of the water reducing agent; in particular to a polycarboxylic acid high-performance water reducing agent which is the most applied in the current concrete and has the figure in all large projects.

However, most polycarboxylic acid water reducers in the market at present mainly comprise mother liquor water agents, the solid content of products is generally about 40-50%, so the cost is increased in transportation, the application of the polycarboxylic acid water reducers in engineering construction such as sprayed concrete, dry-mixed mortar and the like is limited, although the mother liquor of the water reducers can be directly converted into powder polycarboxylic acid by using a spray drying method, the spray drying method has high energy consumption, and partial products can be lost in drying and have safety problems in production.

CN108192041A discloses a preparation method and application of a powdery polycarboxylate superplasticizer, and the preparation method and application of the powdery polycarboxylate superplasticizer after spray drying comprise the steps of preparing a polycarboxylate monomer a, a benzene ring-containing small monomer b and a benzene ring-containing polyether monomer c in an aqueous medium through free radical copolymerization to obtain a polycarboxylate superplasticizer mother liquor; directly forming fog drops from the polycarboxylate superplasticizer mother liquor through a centrifugal atomizer of the sprayer without adding an isolating agent, controlling the average particle size of powder to be 50-150um, drying the fog drops into powder after the fog drops enter a drying chamber, guiding the material to a discharge port through an induced draft fan, and packaging and discharging the material by adopting a bag packaging machine to obtain the powdery polycarboxylate superplasticizer. The invention has certain loss in the process of spray centrifugation, the temperature required by spray drying is higher, and the energy consumption requirement under the same yield is overhigh.

CN108484841A discloses a preparation method of a solid sheet-shaped polycarboxylate superplasticizer by bulk polymerization, wherein a certain amount of freshly synthesized liquid polyether monomer and viscosity reducer are added into a reaction kettle, and the mixture is stirred and heated; controlling the temperature at 100-105 ℃, and starting to add a certain amount of initial initiator, organic peroxide initiator, solubilizer, chain transfer agent and initial initiator; after 5min, beginning to drop small monomer solution, wherein the dropping time of the small monomer solution is a hours, and the small monomer solution consists of a certain proportion of fluoro functional monomer and acrylic acid; after the small monomer solution is dripped for 10min, a certain amount of organic peroxide initiator is added into the kettle, and then the small monomer solution is added once every 10min until the small monomer solution is added for the last time before the small monomer solution is dripped; after the dripping is finished, the temperature is raised to be at 110-115 ℃, the temperature is kept constant, the mixture is cured for b hours, and then the mixture is cooled, sliced and packaged to obtain the solid sheet-shaped polycarboxylate superplasticizer. The invention has relatively complex process in the synthesis process, and has high energy consumption loss due to high reaction temperature.

It is noted that the information disclosed in the foregoing background section is only for enhancement of background understanding of the invention and therefore it may contain information that does not constitute prior art that is already known to a person of ordinary skill in the art.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide the solid polycarboxylic acid water reducing agent which has good workability and lower production and transportation costs.

In order to achieve the purpose, the invention adopts the following technical scheme:

a preparation method of a solid polycarboxylic acid water reducing agent comprises the following steps:

melting polyether monomer and hyperbranched monomer into liquid;

adding an initiator into the liquid, stirring, and then adding unsaturated carboxylic acid and a chain transfer agent to obtain a mixed solution; and

and carrying out aging treatment on the mixed solution, and then cooling and solidifying to obtain the solid polycarboxylic acid water reducing agent.

In some embodiments, the polyether monomer is added in an amount of 82 to 89% by mass, the hyperbranched monomer is added in an amount of 0.4 to 3% by mass, the unsaturated carboxylic acid is added in an amount of 7 to 11% by mass, the chain transfer agent is added in an amount of 0.2 to 0.7% by mass, and the initiator is added in an amount of 0.4 to 1.5% by mass, based on the total mass of the raw materials.

In some embodiments, the polyether monomer is selected from one or more of methallyl polyoxyethylene ether, prenol polyoxyethylene ether, and hydroxybutyl polyoxyethylene ether, and the molecular weight of the polyether monomer is 1200-5000, preferably 2000-4000.

In some embodiments, the hyperbranched monomer has a structure according to formula I, wherein n is an integer from 1 to 15, m is an integer from 1 to 10, x is an integer from 1 to 10, and y is an integer from 1 to 10.

In some embodiments, the initiator is selected from one or more of benzoyl peroxide, lauroyl peroxide, ammonium persulfate, potassium persulfate, sodium persulfate, azobisisobutyronitrile, azobisisoheptonitrile, azobisisovaleronitrile, azobisdicyclohexylcarbonitrile, dimethylisobutyric acid, dicyclohexyl dicarbonate peroxide, and hexacosanyl peroxydicarbonate.

In some embodiments, the unsaturated carboxylic acid is selected from one or more of acrylic acid, methacrylic acid, itaconic acid, maleic anhydride, maleic acid, and fumaric acid.

In some embodiments, the chain transfer agent is selected from one or more of sodium methallyl sulfonate, sodium allyl sulfonate, thioglycolic acid, mercaptopropionic acid, mercaptoethanol, n-dodecyl mercaptan, sodium hypophosphite, sodium vinyl sulfonate, sodium propenyl sulfonate, and sodium styrene sulfonate.

In some embodiments, the unsaturated carboxylic acid and chain transfer agent are added to the liquid by a dropwise addition method over a period of 0.5 to 2 hours.

In some embodiments, the aging treatment time is 0.5 to 3 hours.

In another aspect, the invention provides a solid polycarboxylic acid water reducing agent, which is prepared according to the method.

The hyperbranched monomer is added into the solid polycarboxylate superplasticizer, so that the requirement on viscosity during polymerization is reduced, the concrete workability is good in the concrete evaluation process, the phenomena of bleeding, slurry bleeding, stone leakage and the like are avoided, and the viscosity of the concrete can be reduced under the condition of low water-cement ratio. In addition, the anhydrous solid polycarboxylate water reducer product is obtained after the preparation of the method is finished, the powder polycarboxylate water reducer can be obtained without spray drying like the traditional mother liquor water agent, and compared with the powder polycarboxylate water reducer, the production cost and the long-distance transportation cost are greatly reduced.

Detailed Description

The technical solution of the present invention is further explained below according to specific embodiments. The scope of protection of the invention is not limited to the following examples, which are set forth for illustrative purposes only and are not intended to limit the invention in any way.

The invention provides a preparation method of a solid polycarboxylate superplasticizer, which comprises the following steps:

melting polyether monomer and hyperbranched monomer into liquid;

adding an initiator into the liquid, stirring, and then adding unsaturated carboxylic acid and a chain transfer agent to obtain a mixed solution; and

and carrying out aging treatment on the mixed solution, and then cooling and solidifying to obtain the solid polycarboxylic acid water reducing agent.

According to the total mass of the raw materials, the addition amount of the polyether monomer is 82-89%, the addition amount of the hyperbranched monomer is 0.4-3%, the addition amount of the unsaturated carboxylic acid is 7-11%, the addition amount of the chain transfer agent is 0.2-0.7%, and the addition amount of the initiator is 0.4-1.5%.

The polyether monomer and the hyperbranched monomer are firstly melted into liquid within a certain temperature range, the polyether monomer can be completely melted firstly, and then the hyperbranched monomer is added for melting. The temperature of the material can be controlled between 65 and 100 ℃.

The polyether monomer used in the invention is selected from one or more of methyl allyl polyoxyethylene ether, isoamylol polyoxyethylene ether and hydroxybutyl polyoxyethylene ether, and the molecular weight of the polyether monomer is 1200-5000, preferably 2000-4000.

The hyperbranched monomer used in the invention is a polymer obtained by adding ethylene oxide and propylene oxide random block into polyethylene polyamine as a raw material, and has a structure shown in a formula I, wherein n represents the addition number of Ethylene Oxide (EO), which is an integer from 1 to 15, preferably an integer from 3 to 10, m represents the addition number of Propylene Oxide (PO), which is an integer from 1 to 10, preferably an integer from 2 to 6, x is an integer from 1 to 10, and y is an integer from 1 to 10.

After the polyether monomer and the hyperbranched monomer are melted into liquid, an initiator is added into the liquid and stirred, the initiator used in the invention is an oil-soluble initiator which is selected from one or more of benzoyl peroxide, lauroyl peroxide, ammonium persulfate, potassium persulfate, sodium persulfate, azobisisobutyronitrile, azobisisoheptonitrile, azobisisovaleronitrile, azobisdicyclohexyl carbonitrile, azobisisobutyric acid dimethylku, dicyclohexyl peroxydicarbonate and hexacosanyl peroxydicarbonate, and the stirring time is usually 5-10 min.

Adding an initiator and stirring, and then adding unsaturated carboxylic acid and a chain transfer agent into the liquid, wherein the unsaturated carboxylic acid and the chain transfer agent can be mixed firstly and then added simultaneously, and the dropwise adding is preferably carried out in a dropwise adding mode, and the dropwise adding time is 0.5-2 h.

The unsaturated carboxylic acid used in the present invention is selected from one or more of acrylic acid, methacrylic acid, itaconic acid, maleic anhydride, maleic acid and fumaric acid.

The chain transfer agent used in the invention is selected from one or more of sodium methallyl sulfonate, sodium allyl sulfonate, thioglycolic acid, mercaptopropionic acid, mercaptoethanol, n-dodecyl mercaptan, sodium hypophosphite, sodium vinylsulfonate, sodium propenyl sulfonate and sodium styrene sulfonate.

And adding unsaturated carboxylic acid and a chain transfer agent to obtain a mixed solution, and continuously stirring at a constant temperature to carry out aging treatment on the mixed solution, wherein the aging treatment time is 0.5-3 h.

After aging treatment, cooling to about 60 ℃, discharging, and solidifying the product at room temperature to obtain the anhydrous solid polycarboxylic acid water reducing agent.

The solid polycarboxylate superplasticizer prepared by the method can be prepared into liquids with different concentrations by adding water into the solid polycarboxylate superplasticizer according to different construction requirements or further processed into a powdery solid polycarboxylate superplasticizer, the powdery solid polycarboxylate superplasticizer can be directly doped into dry-mixed mortar or sprayed concrete for use, and the original performance of the polycarboxylate superplasticizer cannot be reduced in the process of changing the form.

The hyperbranched monomer is added into the solid polycarboxylate superplasticizer, so that the requirement on viscosity during polymerization is reduced, the solid polycarboxylate superplasticizer is stable in state, and cannot be bonded when being stored at room temperature. The solid polycarboxylate superplasticizer disclosed by the invention has excellent water-reducing and dispersing effects, has good workability on concrete in a concrete evaluation process, does not have the phenomena of bleeding, slurry bleeding, stone leakage and the like, can still show good fluidity and holding capacity under low mixing amount, can keep good workability under different mixing amounts, and shows strong adaptability to different varieties of cement.

In addition, the preparation process can directly obtain the anhydrous solid polycarboxylate water reducer product, the powdery polycarboxylate water reducer can be obtained without spray drying like the traditional mother liquor water agent, the production process and the production period are simpler and shorter than the traditional polycarboxylate water reducer mother liquor, the operation is more convenient, the advantages of the product in transportation distance and transportation cost are more obvious, and meanwhile, if the polyether hot material can be used for producing the solid polycarboxylate water reducer, the assembly cost can be saved by about 30%, and the energy conservation and consumption reduction of a water reducer manufacturer are greatly improved.

Therefore, the preparation method disclosed by the invention is environment-friendly in overall process, beneficial to industrial production and industrial popularization and application, and has good economic benefits and social significance.

The present invention is further illustrated by the following specific examples, which describe preferred embodiments, but which are not to be construed as limiting the invention, and any person skilled in the art may, by applying the above teachings, modify the equivalent embodiments equally.

Examples

Preparation of hyperbranched monomers

40g of polyethylene polyamine and 0.2g of catalyst are put in a 0.3L dry stainless steel high-pressure reaction kettle, nitrogen is introduced into the closed reaction kettle for 3 times of replacement, the temperature is raised to 120 ℃, 29.34g of ethylene oxide and 23.2g of propylene oxide are slowly added into the reaction kettle simultaneously, the reaction temperature is maintained at 120-130 ℃ in the material introducing process, the pressure is 0.3-0.4MPa, the mixture is continuously stirred for 1h at 120 ℃ after the material introduction is finished, and then the mixture is cooled to about 75-80 ℃ for discharging, thus obtaining the hyperbranched monomer.

Example 1

Firstly, 350g of methyl allyl polyoxyethylene ether (theoretical molecular weight of 2400) is put into a reactor, the temperature is raised to 70 ℃, after the materials are completely melted into liquid, 3.5g of hyperbranched monomer obtained in the preparation example is added, the mixture is continuously stirred for 10min, 3.5g of initiator is added, after stirring for 10min, the mixture of 37.5g of acrylic acid and 2g of mercaptoacetic acid is dripped, the dripping reaction time is controlled to be 1h +/-5 min, after the reaction is finished, the temperature is raised to 75 ℃, aging is carried out for 2h, after the aging is finished, the mixture is poured into a tray for discharging, and after the product is solidified, the anhydrous solid polycarboxylic acid water reducer can be obtained.

Example 2

357g of methyl allyl polyoxyethylene ether (with the theoretical molecular weight of 3000) is put into a reactor, the temperature is raised to 75 ℃, after the materials are completely melted into liquid, 4g of hyperbranched monomer obtained in the preparation example is added, the stirring is continued for 10min, 3.6g of benzoyl peroxide is added as an initiator, after the stirring for 10min, the dropping and feeding of a mixed dropping material of 37.9g of acrylic acid and 2.2g of sodium hypophosphite are started, the dropping reaction time is controlled to be 1h +/-5 min, after the reaction is finished, the aging is carried out for 2h, after the aging is finished, the mixed dropping material is poured into a tray for discharging, and after the product is solidified, the anhydrous solid polycarboxylic acid water reducer can be obtained.

Example 3

Firstly, 351g of methyl allyl polyoxyethylene ether (theoretical molecular weight is 3000) is put into a reactor, the temperature is raised to 75 ℃, after the materials are completely melted into liquid, 5g of hyperbranched monomer obtained in the preparation example is added, the stirring is continued for 10min, 4g of azodiisobutyronitrile is added as an initiator, after the stirring is carried out for 10min, the mixed dripping feeding of 35.3g of acrylic acid, 1.5g of mercaptopropionic acid and 0.7g of mercaptoethanol is started, the dripping reaction time is controlled to be 1h +/-5 min, after the reaction is finished, the aging is carried out for 2h, after the aging is finished, the tray is poured for discharging, and after the product is solidified, the anhydrous solid polycarboxylic acid water reducer can be obtained.

Example 4

Firstly, 345g of prenyl alcohol polyoxyethylene ether (theoretical molecular weight of 2400) is put into a reactor, the temperature is raised to 75 ℃, after the materials are completely melted into liquid, 5g of hyperbranched monomer obtained in the preparation example is added, the stirring is continued for 10min, 4g of azodiisobutyronitrile is added as an initiator, after the stirring is carried out for 10min, the dropping and feeding of a mixed dropping material of 40.2g of methacrylic acid and 2.3g of sodium hypophosphite is started, the dropping reaction time is controlled to be 1.5h +/-5 min, the aging is carried out for 2.5h after the reaction is finished, the mixture is poured into a tray for discharging after the aging is finished, and the anhydrous solid polycarboxylic acid water reducer can be obtained after the product is solidified.

Example 5

Firstly, 326g of prenyl alcohol polyoxyethylene ether (theoretical molecular weight is 3000) is put into a reactor, the temperature is raised to 70 ℃, after the materials are completely melted into liquid, 6g of hyperbranched monomer obtained in the preparation example is added, the stirring is continued for 10min, 2g of azobisisobutyronitrile and 2.5g of azobisisovaleronitrile are added as initiators, after the stirring is continued for 10min, a mixed dropwise addition material of 36.2g of methacrylic acid and 2.3g of sodium hypophosphite is started to be dropwise added, the dropwise addition reaction time is controlled to be 1.5h +/-5 min, the aging is carried out for 2.5h after the reaction is finished, after the aging is finished, a tray is poured for discharging, and after the product is solidified, the anhydrous solid polycarboxylic acid water reducer can be obtained.

Example 6

Firstly, 364g of hydroxybutyl polyoxyethylene ether (theoretical molecular weight of 2400) is put into a reactor, the temperature is raised to 75 ℃, after the materials are completely melted into liquid state, 6g of hyperbranched monomer 3 obtained in the preparation example is added, stirring is continued for 10min, 3.8g of ammonium persulfate is added, after stirring for 10min, a mixed dropwise addition material of 30.9g of methacrylic acid and 3g of sodium methallylsulfonate is started to be dropwise added, the dropwise addition reaction time is controlled to be 1h +/-5 min, aging is carried out for 2.5h after the reaction is finished, a tray is poured for discharging after the aging is finished, and the anhydrous solid polycarboxylic acid water reducer can be obtained after the product is solidified.

Example 7

Firstly, 350g of hydroxybutyl polyoxyethylene ether (theoretical molecular weight is 3000) is put into a reactor, the temperature is raised to 75 ℃, after the materials are completely melted into liquid, 3g of hyperbranched monomer obtained in the preparation example is added, the mixture is continuously stirred for 10min, 3.8g of ammonium persulfate is added as an initiator, after the mixture is stirred for 10min, the mixed dripping feeding of 30.9g of methacrylic acid and 3g of sodium methallyl sulfonate is started, the dripping reaction time is controlled to be 1h +/-5 min, the mixture is aged for 2.5h after the reaction is finished, the mixture is poured into a tray for discharging after the aging is finished, and the anhydrous solid polycarboxylic acid water reducer can be obtained after the product is solidified.

Example 8

342g of hydroxybutyl polyoxyethylene ether (theoretical molecular weight of 3600) is put into a reactor, the temperature is raised to 80 ℃, after the materials are completely melted into liquid, 4g of hyperbranched monomer obtained in the preparation example is added, the stirring is continued for 10min, 3.5g of azodiisobutyronitrile is added, after the stirring is carried out for 5min, the dropwise addition of a mixed dropwise addition material of 32.7g of methacrylic acid, 7g of itaconic acid, 1g of mercaptopropionic acid and 0.7g of mercaptoethanol is started, the dropwise addition reaction time is controlled within 1h +/-5 min, the aging is carried out for 2h after the reaction is finished, the discharging is carried out by pouring into a tray after the aging is finished, and the anhydrous solid polycarboxylic acid water reducer can be obtained after the product is solidified.

The solid polycarboxylic acid water reducing agents prepared in examples 1 to 8 were uniformly put into an oven to be melted, and the viscosities of the samples of examples 1 to 8 and the viscosities of comparative examples 1 to 8 were measured at 70 ℃ using a petroleum product kinematic viscometer using a comparative example only without adding a hyperbranched monomer under the same conditions as in the examples, and the molecular weights of the samples of examples 1 to 8 and the samples of comparative examples 1 to 8 (without adding a hyperbranched monomer) were measured by gel liquid chromatography, and the results are shown in table 1.

TABLE 1 comparison of viscosity and molecular weight of solid polycarboxylic acid water reducing agent prepared in examples and comparative examples

The test leads to the conclusion that: after the hyperbranched monomer is added, the viscosity of the sample is generally between 3000 and 3500, the viscosity of the sample without the hyperbranched monomer is generally between 4900 and 5500, and the molecular weight of the solid polycarboxylic acid water reducing agent product is not greatly changed; the viscosity of the solid polycarboxylate water reducer is obviously reduced by adding the hyperbranched monomer, and the reduction of the viscosity shows that the requirement on equipment in production of the solid polycarboxylate water reducer is reduced, so that the yield of the product in the forming and slicing process is improved, and more space is provided for improving the profit of the product.

The solid polycarboxylic acid water reducing agent prepared in the examples 1 to 8 is prepared into a water reducing agent with a concentration of 10%, according to the test requirements of a high-performance water reducing agent in the GB8076-2008 "concrete admixture" standard, the performance of the sample synthesized in the example is compared with that of a commercial water reducing agent (HD-14 high-performance polycarboxylic acid water reducing agent produced by Shenyang Haida building materials factory), the experimental formula is shown in Table 2, and the concrete performance test results are shown in tables 3 and 4.

TABLE 2 concrete test ratio (kg/m)³)

TABLE 3 concrete Performance test results for Mount thousand Cement 42.5

TABLE 4 concrete Performance test results for Oncomelania Hupensis Cement 42.5

The experimental results show that the solid polycarboxylate superplasticizer prepared by the invention has good adaptability to different varieties of cement, has higher water reducing rate and retention performance compared with the traditional polycarboxylate superplasticizer mother liquor, and the hyperbranched monomer is added in the invention to reduce the product viscosity and the concrete bleeding rate, so that the concrete workability is improved to a certain extent without obvious bleeding, slurry bleeding and stone leakage.

It should be noted by those skilled in the art that the described embodiments of the present invention are merely exemplary and that various other substitutions, alterations, and modifications may be made within the scope of the present invention. Accordingly, the present invention is not limited to the above-described embodiments, but is only limited by the claims.