CN116284605A

CN116284605A - Solid polycarboxylate superplasticizer and preparation method thereof

Info

Publication number: CN116284605A
Application number: CN202310352672.8A
Authority: CN
Inventors: 范士敏; 陈烽; 曾君; 潘玉杰; 马欣悦
Original assignee: Ningbo Conch New Material Technology Co ltd; Anhui Conch Material Technology Co ltd
Current assignee: Ningbo Conch New Material Technology Co ltd; Anhui Conch Material Technology Co ltd
Priority date: 2023-04-04
Filing date: 2023-04-04
Publication date: 2023-06-23

Abstract

The invention provides a solid polycarboxylate water reducer and a preparation method thereof, wherein polyether macromonomer, water, an activity excitant and an oxidant are mixed to be used as a base material; then taking unsaturated carboxylic acid monomers as a material A, taking an aqueous solution of a chain transfer agent and a reducing agent as a material B, simultaneously dripping the material A and the material B into a base material under a heating condition, carrying out heat preservation reaction after dripping, and adding caustic soda flakes for neutralization to obtain a polycarboxylate water reducer mother solution; then transferring the mother solution of the polycarboxylate water reducer into a first-stage devolatilization device, and devolatilizing under heating conditions; then transferring into a secondary mixing device, and adding a drying agent; finally, transferring the solid polycarboxylate water reducer into a slicing device to obtain a finished product of the solid polycarboxylate water reducer, wherein the water content is less than 3%, and the solid content of the polycarboxylate water reducer is more than 97%. Compared with the prior art, the preparation method is simple, the production energy consumption is low, and the product performance is excellent.

Description

Solid polycarboxylate superplasticizer and preparation method thereof

Technical Field

The invention belongs to the field of concrete additives, and particularly relates to a solid polycarboxylate water reducer and a preparation method thereof.

Background

The solid polycarboxylate water reducer (Solid Polycarboxylate Superplasticizer, hereinafter referred to as SPC) is a common additive in the fields of dry-mixed mortar, cement-based grouting materials, sprayed concrete and the like, can be directly mixed with various powder materials and packaged, is in a physical mixing state before water is added for use, and effectively releases the working performance of the SPC when the water is added for use. Furthermore, the traditional polycarboxylate superplasticizer mother liquor is contained between 40% and 50%, the long-distance transportation cost is high, and if the polycarboxylate superplasticizer mother liquor is transported in an SPC mode, the transportation cost of the polycarboxylate superplasticizer can be remarkably saved.

The literature and patent reports show that the spray drying method is the main method for producing and applying the solid polycarboxylate water reducer at present, the polycarboxylate water reducer is prepared into 20% -30% aqueous solution, then 5% -10% anti-adhesive (generally inorganic powder with particle size of 5-20 mu m, such as calcium carbonate, fumed silica, alumina, calcium oxide, talcum powder and the like) is added, the powder polycarboxylate water reducer is obtained by fully and uniformly mixing, and then the powder polycarboxylate water reducer is obtained by atomizing and drying the polycarboxylate water reducer through a spray drying device under the working condition of air inlet temperature of 180-200 ℃. The technology has high energy consumption (about 70% of water needs to be removed) in the drying process, and the effective content of the polycarboxylate superplasticizer is reduced due to the anti-adhesive agent, and the water reduction rate is only about 85% -90% of that of the liquid polycarboxylate superplasticizer.

Chinese patent CN111362615A, CN107652402A, CN109535340a and the like introduce a rigid benzene ring structure into the polycarboxylate water reducer, so as to raise the softening point of the finally prepared polycarboxylate water reducer and reduce the dosage of anti-binder, thereby improving the problems of caking and low effective content of the powder polycarboxylate water reducer. Furthermore, the traditional aqueous phase free radical polymerization method is adopted, so that the conversion rate of polyether monomers is ensured, and the problem that the polycarboxylate water reducer is difficult to spray dry into powder due to excessive unconverted polyether monomers in the subsequent spray drying process is avoided. However, the spray-drying process of the polycarboxylate water reducer still requires a large amount of water removal, resulting in high energy consumption in the drying process.

Another method for preparing solid polycarboxylate water reducer, which is more studied, is a bulk polymerization method, and the existing aqueous phase free radical polymerization mode is not adopted to prepare the polycarboxylate water reducer. The bulk polymerization reaction temperature is higher, the polyether macromonomer becomes liquid after reaching the melting point, azodiisobutyronitrile or benzoyl peroxide is adopted as a free radical initiator, unsaturated carboxylic acid and chain transfer agent solution are respectively or dropwise added into a reaction system after being mixed, and the obtained polycarboxylate water reducer is directly sliced to obtain the powder polycarboxylate water reducer. The bulk polymerization methods of polycarboxylate water reducers are reported in Chinese patents CN 110240676A, CN 108084362A, CN 114685729A, CN 108821633A and the like. The bulk polymerization mode has the advantages of convenient production process, obvious energy-saving effect and the like, but the viscosity is larger in the later stage of bulk polymerization, and mass transfer, heat transfer and the like are all adversely affected to a certain extent. Furthermore, the monomer conversion rate of the polycarboxylate water reducer synthesized by adopting the bulk polymerization method is lower and is generally 80-90%, and the polymerization effect of the traditional water phase free radical polymerization method is difficult to achieve.

In conclusion, the solid polycarboxylate water reducer has certain advantages in the aspects of saving transportation cost, packaging and product application range, is one of the development directions of the polycarboxylate water reducer, has the defects of higher energy consumption, low effective content, insufficient monomer conversion rate and the like in the spray drying method and the bulk polymerization method which are researched and applied more at present, and increases the production cost and the difficulty of large-scale popularization and application of the solid polycarboxylate water reducer.

Disclosure of Invention

The invention aims to provide a solid polycarboxylate water reducer and a preparation method thereof, wherein the preparation method is simple, the production energy consumption is low, and the product performance is excellent.

The specific technical scheme of the invention is as follows:

the preparation method of the solid polycarboxylate superplasticizer comprises the following steps:

1) Mixing polyether macromonomer, water, an activity excitant and an oxidant to serve as a base material; then taking unsaturated carboxylic acid monomers as a material A, taking an aqueous solution of a chain transfer agent and a reducing agent as a material B, simultaneously dripping the material A and the material B into a base material under a heating condition, carrying out heat preservation reaction after dripping, and adding caustic soda flakes for neutralization to obtain a polycarboxylate water reducer mother solution;

2) Transferring the mother solution of the polycarboxylate water reducer into a first-stage devolatilization device, and devolatilizing under heating conditions; then transferring into a secondary mixing device, and adding a drying agent; and finally transferring into a slicing device to obtain the solid polycarboxylate superplasticizer finished product.

In step 1), the polyether macromonomer is a commercially available polyether macromonomer product comprising the commonly used HPEG, TPEG, EPEG and VPEG product grades, number average molecular weight (M _n ) Between 2000 and 6000, the molecular structure of the polyether macromonomer is shown as the following formula:

r is H, -CH ³ One of them, X is-CH ₂ -，-CH ₂ -CH ₂ -，-O-CH ₂ -CH ₂ -，-O-CH ₂ -CH ₂ -O-CH ₂ -CH ₂ -，-O-CH ₂ -CH ₂ -CH ₂ -CH ₂ -，-O-CH ₂ -CH(CH ₃ )-CH ₂ -one of the following.

In the step 1), the water is common process water, and the dosage is 10-20% of the mass of the polyether macromonomer.

In the step 1), the activity excitant is used for guaranteeing the polymerization activity of each monomer in a high-solid-content system and improving the conversion rate of the polyether macromonomer. The invention adopts ferrous salt as an activity excitant, wherein the ferrous salt is selected from one of ferrous sulfate, ferrous chloride and ferrous nitrate; preferably, the activity excitant is: the ferrous salt is prepared into ferrous salt water solution with the mass concentration of 0.01 percent, and the dosage of the ferrous salt water solution is 0.05 to 0.1 percent of the mass of the polyether macromonomer.

In step 1), the oxidizing agent does not use hydrogen peroxide which is easily decomposed and volatilized as the oxidizing agent in consideration of the polymerization temperature. Preferably, the oxidant used in the invention is persulfate, preferably one of ammonium persulfate and sodium persulfate, as the oxidant; the consumption of the oxidant is 0.2% -1.0% of the mass of the polyether macromonomer.

In the step 1), the material A is an unsaturated carboxylic acid monomer, and comprises one or more monomers of maleic anhydride, acrylic acid, itaconic anhydride, methacrylic acid, hydroxyethyl acrylate, hydroxypropyl acrylate and the like. Wherein maleic anhydride, itaconic acid, methacrylic acid and other unsaturated carboxylic acid monomers which are solid at normal temperature are directly added into the base solution; the dosage of the unsaturated carboxylic acid monomer is 10-15% of the mass of the polyether macromonomer.

In the step 1), the material B is a mixed aqueous solution of a chain transfer agent and a reducing agent; the chain transfer agent is one of mercaptoethanol, mercaptopropionic acid and mercaptoacetic acid; the chain transfer agent is used in an amount of 0.4-0.8% of the mass of the polyether macromonomer; the reducing agent is one of L-ascorbic acid (Vc), sodium metabisulfite and the dosage of the reducing agent is 0.2-0.5% of the mass of the polyether macromonomer.

In step 1), the chain transfer agent and the reducing agent are dissolved using 10% by mass of water based on the mass of the polyether macromonomer.

In step 1), the heating conditions are as follows: the reaction temperature should reach above the melting point of the polyether macromonomer, and the material A and the material B are added dropwise at the same time at 50-65 ℃, the material A is added dropwise for 1.0-3.0h, and the material B is added dropwise for 0.5h longer than the material A.

The reaction is carried out in the heat preservation in the step 1), and the reaction time is 60+/-5 min.

In the step 1), the caustic soda flakes are sodium hydroxide tablets, and the dosage of the caustic soda flakes is the same as the molar dosage of carboxylic acid groups in unsaturated carboxylic acid monomers.

In the step 1), the prepared polycarboxylate superplasticizer mother liquor has effective solid content of 80-90 percent and weight average molecular weight (M) _w ) The conversion rate of the polyether macromonomer is more than or equal to 90 percent and the pH value is between 8 and 10 between 25000 and 45000.

In the step 2), the primary devolatilization device is a commercial double-screw extruder with an electric heating and vacuum devolatilization device. The double screws of the double screw extruder have good material conveying, mixing and heat transfer effects in the rotation engagement process, the influence of the increase of the material viscosity on the devolatilization efficiency is much smaller than that of the stirred tank reactor, and the moisture removal efficiency is higher. The twin-screw extruder equipment is a commercial product and is purchased from a manufacturer of the twin-screw extruder, and the structural formula of the equipment is shown in the following figure 1.

The reaction temperature of the primary devolatilization device is 150-250 ℃, the reaction pressure is-0.1 MPa, and the residence time of materials in the device is 3-10min.

The effective solid content of the mother solution of the polycarboxylate water reducer after passing through the primary devolatilization device is more than or equal to 97%.

The secondary mixing device is a conventional commercial double-screw extruder, and the double screws are used for fully mixing and conveying materials in the rotating and meshing process, and the structural formula of the secondary mixing device is shown in the following figure 2.

In the step 2), the drying agent is an inorganic drying agent or an organic drying agent, and the dosage of the drying agent is 0.05-0.25% of the mass of the polycarboxylate superplasticizer mother liquor.

The inorganic desiccant is one of sodium thiosulfate, sodium sulfate, sodium carbonate, ferrous sulfate, zinc sulfate, magnesium sulfate, alum, calcium chloride, calcium nitrate, calcium oxide, copper sulfate and the like. In view of the color, chloride ion content, and influence on the performance of the polycarboxylate water reducer, it is preferable that the inorganic desiccant of the present invention is one of sodium thiosulfate, sodium sulfate, sodium carbonate, calcium oxide, or the like.

The organic drying agent is commercial water-absorbent resin, and the main component is sodium polyacrylate or sodium polymethacrylate, and the weight average molecular weight is 100-200 ten thousand. The water-absorbing resin not only can be used as a drying agent of the solid polycarboxylate water reducer, but also has the effect of thickening and retaining water after being dissolved by adding water, and can further improve the working performance of the polycarboxylate water reducer.

The secondary mixing device has a material mixing temperature of 100-150 ℃ and a material residence time in the device of 3-10min.

In the step 2), the slicing device is a drum-type slicing machine for slicing common commercial polyether macromonomer.

The solid polycarboxylate water reducer provided by the invention is prepared by adopting the method, is in the shape of tan flakes and powder, has the water content of less than 3%, and has the solid content of more than 97%.

The invention provides a preparation method of the solid polycarboxylate water reducer, which has the advantages of simple preparation process, low production energy consumption and excellent product performance. Specifically, the preparation method of the solid polycarboxylate superplasticizer provided by the invention has the following advantages:

1. according to the invention, the high-solid content polycarboxylate water reducer mother liquor is prepared by a water phase free radical polymerization method, and the conversion rate and the water reducing effect of the polyether macromonomer are ensured by using the activity excitant, so that the dehydration energy consumption is reduced. Compared with the bulk polymerization method, the conversion rate and the water reducing effect of the polyether macromonomer are improved; compared with a spray drying method, the solid content of the polycarboxylate water reducer is improved from 20% -30% to 80% -90%, and the dehydration energy consumption can be saved by 50% -70%.

2. According to the invention, the carboxylic acid groups in the polycarboxylate superplasticizer are completely neutralized to sodium carboxylate groups by using caustic soda flakes, so that on one hand, the solid content of the polycarboxylate superplasticizer mother liquor is further improved, and the devolatilization energy consumption is reduced; on the other hand, the method is helpful for avoiding the dehydration and esterification reaction between the main chain carboxylic acid group and the terminal hydroxyl of the polyether side chain in the high-temperature drying process, and the high molecular weight crosslinked polymer is formed to influence the dissolution and water reduction performance of the subsequent solid polycarboxylate water reducer.

3. The invention adopts a two-stage double-screw extruder as a devolatilizing device and a mixing device of the high-solid content polycarboxylate water reducer mother solution, plays the advantages of devolatilizing and mixing the high-viscosity materials by the double-screw extruder, and improves the mass and heat transfer effects of the high-viscosity materials. The method can efficiently finish the procedures of dehydration, mixing and the like of the mother solution of the polycarboxylate superplasticizer, and further reduce the energy consumption of the solid polycarboxylate superplasticizer.

4. According to the invention, the drier is used for replacing an anti-adhesive agent to serve as an additive of the solid polycarboxylate water reducer, the drier serves as a filler to play a role of an anti-adhesive agent in the processing process, and the drier serves as the drier to absorb moisture in a finished product of the solid polycarboxylate water reducer, so that the solid polycarboxylate water reducer is prevented from being deliquesced to cause adhesion and blocking. Furthermore, the organic drying agent can be used as a thickening agent or a water-retaining agent after being dissolved in concrete, so that the working performance of the polycarboxylate water reducer is further improved.

Compared with the prior art, the method has the advantages that the polycarboxylic acid water reducer mother liquor with the solid content of 70-80% is prepared by water phase free radical polymerization, the carboxylic acid groups are completely neutralized by using equimolar amount of caustic soda flakes, the solid content is further improved to 80-90%, the dehydration energy consumption mother liquor is reduced, inorganic salt capable of forming crystal water or high molecular sodium polyacrylate or sodium polymethacrylate with excellent water absorption performance is used as a drying agent, and the drying agent is used for replacing an anti-adhesive agent and has low consumption; the double-screw extruder is adopted as a dehydration and mixing device for high-viscosity materials, so that the efficiency is improved, and the energy consumption is reduced; the invention improves the working performance of the final water reducer by utilizing the water retention effect of the high molecular weight sodium polyacrylate.

Drawings

FIG. 1 is a schematic diagram of a primary devolatilizer;

fig. 2 is a schematic diagram of a two-stage mixing device.

Detailed Description

The present invention is described in detail below by way of examples which are illustrative only and are not meant to limit the scope of applicability of the invention, as those skilled in the art will be able to make variations in the chemical reagents, processes and reaction equipment within the scope of the invention in light of the disclosure herein. All equivalent changes or modifications made in accordance with the spirit of the present invention should be construed to be included in the scope of the present invention.

In the embodiment of the invention, the weight average molecular weight, the molecular weight distribution (PDI) and the monomer conversion rate of the polycarboxylate superplasticizer mother liquor are measured by adopting a Wyatt technology corporation gel permeation chromatograph, and the test parameters are as follows: mobile phase 0.1mol/L NaNO ₃ An aqueous solution; the flow phase speed is 1ml/min; sample injection amount is 20 μl; sample concentration 0.5% (sample g/mobile phase g); a detector, namely a Shodex RI-71 type differential refraction detector; standard polyethylene glycol GPC standard (Sigma-Aldrich, molecular weight 1010000,478000,263000,118000,44700,18600,6690,1960,628,232. Solid content was measured using a rapid moisture meter and moisture was measured using the karl fischer method.

The embodiment is divided into two parts, namely, the preparation of the mother solution of the high-solid-content polycarboxylate superplasticizer and the preparation of the solid polycarboxylate superplasticizer. In the embodiment, the parts are specifically referred to as mass parts, and the addition amounts of other materials are converted into mass parts.

1. Example 1-example 7 preparation of high solids polycarboxylate superplasticizer mother liquor:

1. the molecular structure, starter and code of the polyether macromonomer used are shown in Table 1.

Table 1 molecular structure, initiator and code of the polyether macromonomer used

2. The molecular structure and code of the unsaturated carboxylic acid monomer used are shown in table 2.

Table 2 molecular Structure and code of unsaturated Carboxylic acid monomer used

3. The high-solid content polycarboxylate water reducer mother liquor is prepared by adopting the raw materials, a water phase free radical polymerization method is adopted, and polymerization process conditions are adjusted to prepare the high-solid content polycarboxylate water reducer mother liquor with the solid content of 80-90%, and the material proportion table of the polycarboxylate water reducer synthesis is shown in table 3.

Table 3 raw materials and amounts (amounts are parts by mass) of the mother solution of the high-solid content polycarboxylate superplasticizer

4. The preparation method for preparing the high-solid content polycarboxylate superplasticizer mother solution in the above examples 1-7 comprises the following steps:

according to the raw material proportion in Table 3, the polyether macromonomer and water with the formula amount are weighed and put in a reaction kettle, the temperature is raised to 50-65 ℃, and the mixture is fully stirred until the mixture is completely dissolved, so as to obtain base solution. Weighing unsaturated acrylic monomers, and naming the unsaturated acrylic monomers as dropwise adding solution A, wherein maleic anhydride, itaconic acid, methacrylic acid and other unsaturated carboxylic monomers which are solid at normal temperature are directly added into the base solution (in the embodiment 1, maleic anhydride is directly added into the base solution as solid, and dropwise adding of the solution A is not performed); the reducing agent and the chain transfer agent are weighed, dissolved by water accounting for 10 percent of the mass of the polyether macromonomer, fully dissolved into clear liquid and named as dropwise added solution B. Sequentially weighing an activity excitant and an oxidant, adding the activator and the oxidant into a reaction kettle to perform priming (as a bottom material), fully stirring and dissolving the oxidant for 5-10min, controlling the temperature of the reaction kettle at 50-65 ℃, setting the dripping time of the dripping solution A and the dripping solution B, wherein the dripping time of the dripping solution A is 2.5h, the dripping time of the dripping solution B is 30min longer than that of the dripping solution A, and preserving the heat for 1.0h after the dripping is finished. After the reaction is finished, adding caustic soda flakes for neutralization, wherein the dosage is the same as the molar dosage of carboxylic acid groups in unsaturated carboxylic acid monomers; and obtaining the high-solid-content polycarboxylate superplasticizer mother liquor, which is named as PCE-1 to PCE-7 in sequence.

5. The high solid content polycarboxylate water reducer mother liquors PCE-1 to PCE-7 prepared in the above examples 1 to 7 were tested according to a prescribed method, and the test results are shown in Table 4.

Table 4 test data for high solids polycarboxylate water reducing agent mother liquor

2. The solid polycarboxylate water reducer was prepared using the high solid content polycarboxylate water reducer mother liquor prepared in example 1-example 7 above:

1. preparing raw materials: the amounts of the high solids polycarboxylate water reducer mother liquor and the drying agent are shown in Table 5.

TABLE 5 raw materials and amounts of solid polycarboxylate water reducer (amounts are mass parts)

2. The preparation method comprises the following steps: transferring the high-solid content polycarboxylate water reducer mother liquor prepared in the embodiment 1-7 into a first-stage devolatilization device, and devolatilizing under certain temperature and pressure conditions; then transferring into a secondary mixing device, and adding a drying agent according to a certain proportion; and finally transferring into a slicing device to obtain the solid polycarboxylate superplasticizer finished product. The process parameter settings for each apparatus are shown in table 6.

Table 6 production process parameters of solid polycarboxylate superplasticizer

3. And (3) testing the performance of the produced product: the solid polycarboxylate water reducer finished product was tested according to a prescribed method, and the test results are shown in table 7.

Table 7 test data for solid polycarboxylate water reducer finished product

The results of two GPC tests indicate that dehydration does not cause side reactions that crosslink the polycarboxylate water reducer.

Application experiment one:

the fluidity test of cement paste is carried out according to the GB/T8077-2012 standard, the solid polycarboxylic acid water reducer prepared in the embodiment 1-7 of the invention is firstly dissolved into a finished product with 10% of solid content, conch P.O 42.5.5 cement is adopted, the water-cement ratio is 0.29, the additive folding and fixing mixing amount is 0.12% of the cement dosage, and the fluidity of the cement paste is measured on plate glass. Commercially available solid polycarboxylate water reducers were designated GPCE-1 and GPCE-2, respectively, as control samples. Wherein, the effective content of the polycarboxylate water reducer in GPEG-1 is 88.0 percent, the calcium carbonate (anti-caking agent) of 5-20 mu m is 11.0 percent, and the water content is 1.0 percent; the effective content of the GPEG-2 polycarboxylate superplasticizer is 85.0%, the fumed silica (anti-adhesive) is 14%, and the water content is 1.5%. The cement paste test results are shown in Table 8.

Table 8 cement paste fluidity test

From the data in the table, the solid polycarboxylate water reducer obtained by the preparation method of the solid polycarboxylate water reducer has obvious advantages in the aspects of initial water reduction and slump retaining compared with the commercial samples. Further, examples 2 to 4 each contained an unsaturated carboxylic acid ester structure, and the slump retaining ability of the resulting solid water reducer was more excellent.

Application experiment II:

the performance of the solid polycarboxylate water reducer of the present invention was tested using a concrete test. The test was performed with reference to the specifications in national standard GB/T8076-2008 concrete admixture. The adopted cement is conch P.O 42.5.5 cement, and the fly ash is secondary ash; the sand is middle sand with fineness modulus mx=2.6, and the water content of the sand is 5%; the cobble is crushed stone with the particle size of 5-20 mm and continuous grading, and the water content of the cobble is 2%. The folding and solidifying mixing amount of the water reducing agent is 0.16 percent. C30 strength grade concrete volume weight 2317Kg/m ³ The concrete test raw material formulation ratios are shown in Table 9

Table 9 concrete raw material proportioning table

Concrete test data for the finished solid polycarboxylate water reducer are shown in Table 10.

Table 10 concrete test of solid polycarboxylate water reducer

From the data in the table, the solid polycarboxylate water reducer obtained by the preparation method of the solid polycarboxylate water reducer has obvious advantages in the aspects of initial expansion and slump retention of concrete compared with the commercial samples. Still further, examples 5-7 use sodium polyacrylate or sodium polymethacrylate as a desiccant, with the concrete expansion approximating greater slump, exhibiting better workability during concrete application.

Claims

1. The preparation method of the solid polycarboxylate superplasticizer is characterized by comprising the following steps of:

2. The method of claim 1, wherein the step of activating the agent is: the ferrous salt is prepared into ferrous salt water solution with the mass concentration of 0.01 percent, and the dosage of the ferrous salt water solution is 0.05 to 0.1 percent of the mass of the polyether macromonomer.

3. The method according to claim 1, wherein in the step 1), the amount of the oxidizing agent is 0.2 to 1.0% by mass of the polyether macromonomer, and the oxidizing agent is persulfate.

4. The method according to claim 1, wherein in the step 1), the unsaturated carboxylic acid monomer is used in an amount of 10 to 15% by mass of the polyether macromonomer.

5. The method according to claim 1, wherein in step 1), the chain transfer agent is used in an amount of 0.4 to 0.8% by mass of the polyether macromonomer; the consumption of the reducing agent is 0.2% -0.5% of the mass of the polyether macromonomer.

6. The preparation method of claim 1, wherein in the step 1), the prepared polycarboxylate superplasticizer mother liquor has effective solid content of 80-90%, weight average molecular weight of 25000-45000, polyether macromonomer conversion rate of more than or equal to 90% and pH value of 8-10.

7. The process according to claim 1, wherein the reaction temperature of the primary devolatilization apparatus is 150-250 ℃, the reaction pressure is-0.1 Mpa, and the residence time of the material in the apparatus is 3-10min.

8. The process according to claim 1 or 7, wherein the secondary mixing device has a material mixing temperature of 100-150 ℃ and a material residence time in the device of 3-10min.

9. The preparation method according to claim 1, wherein in the step 2), the amount of the drying agent is 0.05-0.25% of the mass of the polycarboxylate water reducer mother liquor.

10. A solid polycarboxylate water reducer prepared by the preparation method as claimed in any one of claims 1 to 9, wherein the solid polycarboxylate water reducer has a water content of < 3% and a solid content of > 97%.