阅读说明：本技术 一种抗泥缓凝型秸秆基聚羧酸减水剂的制备方法和在混凝土中的应用 (Preparation method of mud-resistant slow-setting type straw-based polycarboxylate superplasticizer and application of water-resistant slow-setting type straw-based polycarboxylate superplasticizer in ) 是由 章德玉 张惠琴 左国防 刘流 王鹏 刘岿 司长代 张建斌 唐慧安 王小芳 刘新文 于 2019-02-21 设计创作，主要内容包括：本发明公开一种抗泥缓凝型秸秆基聚羧酸减水剂的制备方法和在混凝土中的应用。是混凝土添加剂减水剂的制备方法。目的是拓展农作物秸秆在混凝土减水剂制备领域,为秸秆全组分利用提供新的可能,继而提高混凝土骨料的强适应性扩展度及抗压强度。本发明的技术方案如下：秸秆预处理、切碎、清洗、烘干、二次粉碎、微碎；秸秆粉料水解预处理；接着进行秸秆木质纤维素磺化一季铵化改性处理,通过螺旋挤出机制得木质素磺酸钠和纤维素硫酸酯；再经多元催化、氧化还原体系进行相应的化学反应,最后制得聚羟酸减水剂。本发明用于混凝土减水剂的制备以添补秸秆基减水剂制备领域的空白。(The invention discloses a preparation method of a mud-resistant slow-setting type straw-based polycarboxylate superplasticizer and application of the straw-based polycarboxylate superplasticizer to concrete. Is a preparation method of the concrete additive water reducing agent. The method aims to expand the field of preparation of the concrete water reducing agent by using crop straws, provide new possibility for full utilization of straw components, and further improve the strong adaptability expansion degree and compressive strength of concrete aggregate. The technical scheme of the invention is as follows: straw pretreatment, chopping, cleaning, drying, secondary crushing and micro crushing; carrying out hydrolysis pretreatment on straw powder; then carrying out sulfonation-quaternization modification treatment on the straw lignocellulose, and obtaining sodium lignosulfonate and cellulose sulfate by a screw extruder; and carrying out corresponding chemical reaction by a multi-element catalysis and oxidation reduction system to finally prepare the polyhydroxy acid water reducing agent. The method is used for preparing the concrete water reducing agent to fill the blank in the field of preparation of the straw-based water reducing agent.)

1. A preparation method of a mud-resistant slow-setting type straw-based polycarboxylate water reducer and application of the water reducer in concrete are characterized in that the preparation process flow of the water reducer is as follows:

(1) pretreatment of straw

1.1, straw raw material cutting, cleaning, drying, secondary crushing and micro-crushing pretreatment: a certain amount of raw material straw bundles (3) are naturally air-dried and then sent into a straw primary crushing device (2) to be crushed into straw sections of 1-3 cm, the straw sections are cleaned by a cleaning device (5), then enter a pre-drying device (6) and a spiral dryer (8) to be secondarily dried, and are crushed into straw sections of less than 10mm by a secondary crushing device (12), and finally enter a horizontal ball mill micro-crushing device (13) to be ball-milled and finely crushed to ensure that the particle size is less than 400 mu m;

1.2 pretreatment of straw powder by hydrolysis

Weighing a certain amount of straw powder prepared in the working procedures through a material collecting bin weighing device (15), feeding the straw powder into a screw extrusion hydrolysis machine (19) for hydrolysis, firstly starting a No. 1 heater (20) to heat the material in the hydrolysis process, slowly adding the prepared liquid in a No. 1-3 prepared liquid storage tank in a No. 1 prepared liquid storage tank group (18) into the screw extrusion hydrolysis machine through a control valve after the preset temperature is reached, and preserving the heat and hydrolyzing for a certain time, wherein the prepared liquid in the No. 1-3 prepared liquid storage tank is respectively a lubricating additive, a hydrolysis main catalytic acid and a cocatalyst acid with certain concentration dosage;

(2) straw lignocellulose is modified by sulfonation-quaternization.

Weighing a certain weight of straw materials prepared by pretreatment through a 2# metering bin weighing device (22), feeding the straw materials into a spiral extrusion reaction unit (26) formed by connecting 1# spiral extruders, 2# spiral extruders, 3# spiral extruders and 4# spiral extruders in series for sulfonation-quaternization modification reaction, starting a 2# heater (28) to heat the materials in the reaction process, sequentially adding a prepared liquid in a 2# prepared material storage tank group (25) after reaching a preset temperature, adding an oxidant with a certain mass concentration in a 1# prepared material storage tank in the 2# prepared material storage tank group (25) through a control valve while feeding the materials into the 1# spiral extruder, feeding the materials into the 2# spiral extruder after reacting for a certain time, adding a sulfonating agent in a 2# prepared material storage tank in the 2# prepared material storage tank group (25), feeding the materials into the 3# spiral extruder after reacting for a certain time, adding an alkali liquor in a 3# prepared material storage tank, adjusting the pH value, discharging materials into a No. 4 screw extruder after reacting for a certain time, adding a quaternization reagent in a No. 4 storage tank, preserving heat for a certain time, and discharging the materials to obtain a mixture of the straw modified sodium lignosulfonate and cellulose sulfate, and quaternization sodium lignosulfonate and cellulose sulfate;

(3) preparing a mud-resistant slow-setting type straw-based polycarboxylate superplasticizer:

3.1 weighing a certain amount of unsaturated polyoxyethylene ether macromonomer and a certain amount of the straw modified mixture prepared above and adding the mixture into a mixing reactor (30);

3.2 adding tap water into the prepared liquid in the No. 1 preparing storage tank in the No. 3 preparing storage tank group (27), stirring and dissolving to prepare a water solution in a certain proportion, adding the water solution into a mixing reactor (30), starting a No. 3 heater (31), and heating the mixing reactor to a certain temperature;

3.3 adding a liquid preparation oxidant in a No. 2 ingredient storage tank in a No. 3 ingredient storage tank group (27) into the mixing reactor (30), and stirring for a certain time;

3.4 adding a certain amount and proportion of unsaturated micromolecule monomers and a mixture thereof in the 3# batching storage tank (27) into the mixing reactor (30), and stirring for a certain time;

3.5 adding a certain amount of reducing agent in a No. 4 ingredient storage tank in a No. 3 ingredient storage tank group (27) into the mixing reactor (30);

3.6 adding a certain amount of chain transfer agent in the No. 5 ingredient storage tank in the No. 3 ingredient storage tank group (27) into the mixing reactor (30), and stirring and reacting for a certain time;

3.7 adding a certain amount of beta-cyclodextrin and dimethyl fumarate from a feed inlet of the mixing reactor, and stirring for a certain time;

3.8 adding the liquid caustic soda in the No. 6 batching storage tank in the No. 3 batching storage tank group (27) into the mixing reactor (30), adjusting the PH value to the required value, finishing the reaction, naturally cooling and aging for a period of time, and discharging to obtain the required product.

2. The method for preparing the water reducing agent according to claim 1, wherein the lubricating additive is one or a combination of stearic acid and oleic acid.

3. The preparation method of the water reducer according to claim 1, characterized in that the hydrolysis primary catalytic acid is one of monocarboxylic acid, dicarboxylic acid or polycarboxylic acid.

4. The preparation method of the water reducing agent according to claim 1, characterized in that the catalysis-assisting acid is dilute sulfuric acid or dilute hydrochloric acid.

5. The method for preparing the water reducing agent according to claim 1, wherein the sulfonating agent is one of sodium sulfite or sodium bisulfite.

6. The preparation method of the water reducing agent according to claim 1, characterized in that the oxidant is hydrogen peroxide or potassium permanganate solution.

7. The preparation method of the water reducing agent according to claim 1, characterized in that the alkali liquor is one of sodium hydroxide or potassium hydroxide.

8. The preparation method of the water reducing agent according to claim 1, characterized in that the quaternizing agent is a polyvinyl ammonium monomer or an unsaturated cationic quaternary ammonium salt.

9. The preparation method of the water reducing agent according to claim 1, characterized in that the polyoxyethylene ether macromonomer is polyethylene glycol monomethyl ether.

10. The preparation method of the water reducing agent according to claim 1, characterized in that the unsaturated small molecule monomer is acrylic acid.

11. The preparation method of the water reducing agent according to claim 1, characterized in that the reducing agent is vitamin C.

12. The preparation method of the water reducing agent according to claim 1, characterized in that the chain transfer agent is sodium methacrylate sulfonate.

13. The preparation method of the water reducing agent according to claim 1, characterized in that the straw primary crushing device, the cleaning device, the pre-drying device, the spiral dryer, the cyclone separator, the secondary crushing device, the horizontal ball mill micro crushing device, the aggregate bin weighing device (3), the buffer storage tanks (2), the batching storage tank group (3), the spiral extrusion hydrolysis machine, the heaters (3), the spiral extrusion reaction unit and the mixing reactor are connected into a complete system by a coarse material conveying air duct, a coarse material output belt and a powder conveying belt.

Technical Field

The invention relates to a preparation method of a concrete admixture water reducing agent, in particular to a preparation method of a mud-retarding straw-based polycarboxylic acid water reducing agent and application thereof in concrete.

Background

At present, along with the increasing shortage of petrochemical raw materials required by a new generation of high-performance petroleum-based polycarboxylate water reducer for preparing a concrete admixture, the price is gradually increased and the high-quality aggregate of concrete is gradually consumed, so that the outstanding problem that the use of low-quality sandstone aggregate with high mud content is forced is solved, the rapid development of the new generation of high-performance polycarboxylate water reducer is restricted, the production cost is continuously increased, and the loss of high performance such as high water reduction, high fluidity, high strength, high durability and the like of the polycarboxylate water reducer in concrete is caused by the high mud content of the sandstone in the concrete, the polycarboxylic acid water reducing agent has the defects that the polycarboxylic acid water reducing agent with higher performance advantage than naphthalene water reducing agents, aliphatic water reducing agents, sulfamate water reducing agents, lignin water reducing agents and the like cannot be widely popularized and applied in the building industry to improve the building quality.

With the problems of high cost, low mud resistance and the like of the polycarboxylic acid water reducing agent serving as a novel additive of concrete, the national and foreign scholars begin to research key bottleneck technical problems such as raw material selection and synthesis methods for preparing the low-cost, mud-resistant and salt-resistant polycarboxylic acid water reducing agent in recent years.

The research on the low-cost polycarboxylate water reducer is mainly embodied in that biomass-based renewable raw materials are used as a main method for reducing the polycarboxylate water reducer, the application of modified cellulose, hemicellulose, starch, monosaccharide and the like in the water reducer is mainly reported at present, and the modification methods mainly comprise sulfonation, esterification, etherification, amidation and the like.

The research on the mud-resistant polycarboxylate water reducer is advanced, and the water reducer is very sensitive to the mud content in concrete sand and stone and has a strong adsorption tendency on clay. The concrete clay (clay) shielding agent, the clay (clay) inhibitor, the clay (clay) resisting agent, the clay resisting sacrificial agent and the like are called differently. The essence of the method is that functional groups are introduced to better disperse and adsorb the clay, so that the adsorption capacity of the clay to the clay is far stronger than that of hydrophilic groups of a main chain of the polycarboxylic acid water reducing agent to the clay. At present, the main research shows that the polycarboxylic acid water reducing agent with mud resistance effect such as amides, phosphates, silanes and the like and the organic and inorganic salt combined mud resistance agent or clay shielding agent with mud resistance performance. The anti-mud agent or the clay shielding agent can be compounded with the polycarboxylic acid water reducing agent for use, and can also be added before the water reducing agent is added for separate use.

At present, few research reports of directly using biomass straws as a water reducing agent exist, and most of the research reports are that cellulose and lignin are extracted and separated from the straws, or black liquor wastewater obtained by producing paper making and ethanol from the straws is used as a raw material for modification research of the water reducing agent or compounding research with a polycarboxylic acid water reducing agent. Chinese patent CN 101337789A, "method for preparing water reducing agent by condensation modification of wheat straw alkali lignin", is to dissolve wheat straw alkali lignin in water of 4.4-5.5 times of the weight of wheat straw alkali lignin, add copper sulfate of 0.6-0.9% of the weight of wheat straw alkali lignin, adjust the pH value to 10-11 with caustic soda solution, add anhydrous sodium sulfite of 45-55% of the weight of wheat straw alkali lignin, heat up to 88-92 ℃, react for 4-5h to prepare sulfonated product, and perform condensation reaction with quantitative formaldehyde under the conditions of pH value of 11.6-12.0 and 65-75 ℃ to prepare the water reducing agent. The water reducing agent prepared by the method has low water reducing rate and can only be used as the most common water reducing agent. Chinese patent CN 101759856B "preparation method of sodium lignosulfonate water reducer", takes black liquor produced by soda boiling of corncobs, corncob acid hydrolysis residues, bagasse or corn stalks as raw materials, and prepares the sodium lignosulfonate water reducer with low water content by coarse filtration, ultrafiltration membrane concentration, sulfonation and spray drying. Chinese patent CN 106698993A, "a polycarboxylate water reducing agent", utilizes waste white mud to size, heat, mix with corn stalk evenly again, add sodium dodecyl sulfate, dry and extrude the piece after stirring, the acid leaching obtains the hydrolyzate, utilize CaO to adjust the pH value of straw hydrolyzate to 6.0-7.0, the hydrolyzate that obtains is dried, oxidized, sulfonated, add to polycarboxylate water reducing agent, use ultrasonic treatment for 1-2 h after stirring evenly, obtain modified polycarboxylate water reducing agent. The method has the main advantages that the papermaking waste liquid is used for preparing the polycarboxylic acid water reducing agent, waste materials can be well changed into valuable materials, and the strong base in the papermaking waste liquid is utilized to pretreat the corn straws, so that the corn straws can be better soaked in acid for hydrolysis. The essence of the method is that lignin in the straws is sulfonated and compounded with a water reducing agent. Chinese patent CN 102936110A, "a lignosulfonate-polycarboxylic acid copolymerization composite high-performance water reducing agent and a preparation method thereof", is obtained by directly synthesizing lignosulfonate, methyl allyl polyoxyethylene ether and acrylic acid under the action of ammonium persulfate and neutralizing with sodium hydroxide. The essence of the water reducing agent is a lignosulfonate modified polycarboxylic acid water reducing agent.

Crop straws are inexpensive biomass raw materials which cannot be fully utilized, and comprise the rest parts of wheat, rice, corn, potatoes, oil plants, cotton, sugarcane and other crops after seeds are harvested. China is a big agricultural country, and most of crop straws which are produced by 7 hundred million or more tons per year are still incinerated, so that resource waste and environmental pollution are caused. The utilization of crop straws has been internationally regarded as a strategic industry for developing renewable energy resources in the 21 st century, and the resource utilization of crop straws mainly focuses on the development of chemical engineering and building materials. At present, the application research of crop straws as building materials is a hotspot, for example. However, the research on the direct use of the water reducing agent as a raw material is very rare. The main components of the straw are cellulose, hemicellulose, lignin and other bio-based macromolecules, the molecules contain ether groups, carbon-carbon double bonds, propenol hydroxyl groups, phenolic hydroxyl groups, carbonyl groups, methoxyl groups, carboxyl groups, benzene rings and other functional groups and chemical bonds, and the graft copolymerization and the cross-linking copolymerization reactions such as etherification, esterification, sulfonation, amidation and the like can be carried out, so that the obtained product has special performance.

The research reports of directly using biomass straws as water reducing agents mainly include: chinese patent CN 106279574A 'A polycarboxylate superplasticizer modified by straws and a preparation method thereof', the first step is straw pretreatment: crushing straws, adding dilute acid, uniformly stirring and mixing, soaking for 18-36h, filtering, and washing the straws to be neutral by using clear water; step two, preparing the straw modified polycarboxylate superplasticizer: adding methallyl polyoxyethylene-1000, methallyl polyoxyethylene-2400, maleic anhydride, acrylamide, sodium methallyl sulfonate and straws into a four-reflux device and a constant-pressure dropping funnel, adding ammonium sulfate into the constant-pressure dropping funnel, beginning to drop initiator ammonium persulfate at the dropping speed of 2-4 drops/s, and preserving heat for 4-5 hours after dropping; cooling to 35-45 ℃, and adjusting the pH value to 6.8-7.2 to obtain the straw modified polycarboxylic acid water reducing agent. Chinese patent CN 105713164B, "an aliphatic water reducer prepared from straws and a preparation method thereof", is prepared by the steps of straw acid cleaning, straw modified aliphatic water reducer and the like. The method specifically comprises the following steps: pretreating straws, namely crushing corn straws or wheat straws, adding dilute acid, uniformly stirring and mixing, soaking for 18-36h, filtering, and washing the straws to be neutral by using clear water; adding water into a reaction kettle, then adding sodium sulfite, and dissolving; adding acetone into the dissolved sodium sulfite solution, and sulfonating for 8-12 min; then adding the pretreated straws, and stirring and reacting for 20-40 min; and adding formaldehyde into the solution, and reacting at 90-95 ℃ for 1-2 h to prepare the straw modified aliphatic water reducer. The technology effectively utilizes the straw waste resources, overcomes the defect of poor retarding effect of the existing aliphatic water reducing agent, improves the application range of the aliphatic water reducing agent, and reduces the production cost. However, the results of the two studies are laboratory shake flask tests, do not suggest the conception and conception of industrial tests, and are far away from industrialization.

The efficient polycarboxylate superplasticizer prepared by directly modifying the crop straws also faces the mud resistance problem of high mud content in the poor-quality concrete aggregate, so that the side effect of the clay is reduced and resisted to the maximum extent, the strong adaptability to the concrete aggregate is improved, the efficient polycarboxylate superplasticizer is also a key problem considered when preparing a novel superplasticizer, and otherwise the efficient polycarboxylate superplasticizer cannot play a role in developing and utilizing the novel superplasticizer. However, the report of the method for directly preparing the mud-resistant polycarboxylate superplasticizer by utilizing the crop straws is not seen yet.

Disclosure of Invention

The invention provides a preparation method of an anti-mud retarding water reducer by modifying crop straws and application of the anti-mud retarding water reducer in concrete, so as to expand the field of direct application of the crop straws in preparation of concrete water reducers with special properties. Thereby providing new possibility for recycling all components of the crop straws.

The technical scheme of the invention is as follows:

1. pretreatment of straw

1.1 pre-treatment of cutting, cleaning, drying, secondary crushing and micro-crushing of the straw raw material.

Taking a certain amount of raw material straw bundles, naturally air-drying the raw material straw bundles, then feeding the raw material straw bundles into a straw primary crushing device, crushing the straw bundles into straw sections of 1-3 cm, washing the straw sections by a washing device, then feeding the straw sections into a pre-drying device and a spiral dryer for secondary drying, crushing the straw sections into straw sections of less than 10mm by a secondary crushing device, and finally feeding the straw sections into a horizontal ball mill micro-crushing device for ball milling and fine crushing to ensure that the particle size is less than 400 mu m;

1.2 pretreatment of straw powder by hydrolysis

Weighing a certain amount of straw powder prepared by the working procedures through a material collecting bin weighing device, feeding the straw powder into a screw extrusion hydrolysis machine for hydrolysis, firstly starting a 1# heater to heat the material in the hydrolysis process, slowly adding the prepared liquid in 1# to 3# material storage tanks in a 1# material storage tank group into the screw extrusion hydrolysis machine through a control valve after the material is heated to a preset temperature, and carrying out heat preservation hydrolysis for a certain time, wherein the 1# material storage tanks, the 2# material storage tanks and the 3# material storage tanks respectively contain a lubricating additive, a hydrolysis main catalytic acid and a cocatalyst with certain concentration and dosage;

2. straw lignocellulose sulfonation-quaternization modification

Weighing a certain amount of straw materials prepared by pretreatment through a No. 2 aggregate bin weighing device, feeding the straw materials into a spiral extrusion reaction unit formed by connecting No. 1, No. 2, No. 3 and No. 4 spiral extruders in series for sulfonation-quaternization modification reaction, starting a No. 2 heater in the reaction process, heating the materials, sequentially adding the prepared liquid in a No. 2 ingredient storage tank group after reaching a preset temperature, feeding the materials into the No. 1 spiral extruder, simultaneously adding an oxidant with a certain mass concentration in a No. 1 ingredient storage tank in the No. 2 ingredient storage tank group through a control valve, feeding the materials into the No. 2 spiral extruder after reacting for a certain time, adding the sulfonating agent in a No. 2 ingredient storage tank in the ingredient storage tank group, feeding the materials into the No. 3 spiral extruder after reacting for a certain time, adding alkali liquor in a No. 3 ingredient storage tank, adjusting the pH value, feeding the materials into the No. 4 spiral extruder after reacting for a certain time, adding a quaternizing agent in a No. 4 storage tank, carrying out heat preservation reaction for a certain time, and then discharging to obtain a mixture of the straw modified sodium lignosulfonate and the cellulose sulfate, and the quaternized sodium lignosulfonate and the cellulose sulfate. The molecular formulas are shown in figure 2, figure 3, figure 4 and figure 5 respectively.

3. And (3) preparing the mud-resistant slow-setting type straw-based polycarboxylate superplasticizer.

3.1, weighing a certain amount of unsaturated polyoxyethylene ether macromonomer and a certain amount of straw modified mixture prepared in the previous paragraph, and adding the mixture into a mixing reactor);

3.2 adding tap water into the prepared liquid in the No. 1 preparing storage tank in the No. 3 preparing storage tank group, stirring and dissolving to prepare a water solution in a certain proportion, adding the water solution into the mixing reactor, and starting the No. 3 heater to heat the mixing reactor to a certain temperature;

3.3 adding a certain amount of liquid preparation oxidant in the No. 2 ingredient storage tank in the No. 3 ingredient storage tank group into the mixing reactor, and stirring for a certain time;

3.4 adding a certain amount and proportion of unsaturated micromolecule monomers and mixtures thereof in the 3# batching storage tank group into the mixing reactor, and stirring for a certain time;

3.5, adding a certain amount of reducing agent in the No. 4 ingredient storage tank in the No. 3 ingredient storage tank group into the mixing reactor;

3.6 adding a certain amount of chain transfer agent in the No. 5 ingredient storage tank in the No. 3 ingredient storage tank group into the mixing reactor, and stirring and reacting for a certain time;

3.7 adding a certain amount of beta-cyclodextrin and dimethyl fumarate from a feed inlet of the mixing reactor, and stirring for reacting for a certain time;

3.8 adding the liquid caustic soda in the No. 6 ingredient storage tank in the No. 3 ingredient storage tank group into the mixing reactor, and adjusting the PH value to the required value to finish the reaction. Naturally cooling and aging for a period of time, and discharging to obtain the prepared product.

FIG. 1 shows a synthesis scheme of the water reducing agent of the present invention.

The invention has the following beneficial effects:

(1) the method expands the application of crop straws in the field of concrete water reducing agents with special properties, changes waste into valuable, and realizes green production of the concrete water reducing agent by using renewable resource raw materials. The defects that the conventional polycarboxylate superplasticizer has high cost and is very sensitive to clay to influence the performance are overcome, and the application range of the anti-mud retarding polycarboxylate superplasticizer is widened;

(2) the straw raw material is degraded by adopting a semidry method (the water content in the straw reaches about 10 percent) spiral extrusion combined organic acid pretreatment method, so that the straw raw material has small corrosion to equipment, high degradation rate, simple reaction process, mild reaction conditions, low cost and easy industrial application;

(3) the organic acid main catalyst used by the straw raw material pretreated by the combination of the semidry method (the water content in the straw is about 10%) and the spiral extrusion and the organic acid can be used as a carboxylic acid monomer required by the subsequent preparation of the water reducing agent, particularly, the unsaturated carboxylic acid monomer can actively participate in the subsequent synthesis of the polycarboxylic acid water reducing agent, and the product performance is not influenced by slight excess;

(4) during the pretreatment of the straw lignocellulose raw material by the semidry method (the water content in the straw is about 10 percent) and the combination of the spiral extrusion and the organic acid, various complex reactions occur, and some small molecular compounds are generated, for example, hydrolysis sugar, organic acid, furfural, 5-hydroxymethyl furfural, phenolic compounds and the like are usually generated in the liquid phase of the pretreated material. Hemicellulose can concomitantly produce compounds such as acetic acid, arabinose, xylose, mannose, galactose and glucose; cellulose can produce glucose; lignin can produce phenolic compounds; extractives and ashes, etc. can produce wood resins, etc. Meanwhile, part of arabinose and xylose are further hydrolyzed and converted into furfural, mannose and galactose, glucose is further hydrolyzed and converted into hydroxymethyl furfural, furfural is further hydrolyzed and converted into formic acid, and hydroxymethyl furfural is further hydrolyzed and converted into formic acid and levulinic acid. The generated small molecular compounds can be used as small molecular monomers required by the synthesis of the water reducing agent and have respective characteristicsSuch as retarding and reducing of water of monosaccharide, polysaccharide, carboxylic acid, slump retaining of furfural and phenolic compounds, etc., and the generated organic weak acid such as formic acid, acetic acid and levulinic acid provides H⁺The hydrolysis is promoted, and the hydrolysis process is accelerated;

(5) has better mud resistance.

Excess hypophosphorous acid, phosphorous acid, phosphoric acid and citric acid used in the raw material pretreatment form sodium salt after subsequent sodium hydroxide neutralization, phosphate has a dispersing effect on soil, sodium citrate has an ion complexing exchange effect, and polyvinyl alcohol used in the water reducing agent synthesis has an adsorption effect on soil. The clay dispersing and adsorbing component preferentially adsorbs the clay in the sandstone aggregate, and the sodium citrate complexes and exchanges ions with high-valence metal ions such as calcium ions on the surface layer of the clay in the clay, so that the adsorption amount of the clay to the polycarboxylic acid water reducing agent is reduced and inhibited. The excessive sodium salt is used as a mud inhibiting agent or a clay sacrificial agent, and has good mud inhibiting and anti-mud effects. A small amount of acrylamide and derivatives thereof are introduced in the synthesis of the water reducing agent to participate in copolymerization, and amine cations generated by amide groups in the molecular structure of the water reducing agent in a strong alkaline environment of cement have a sealing effect on clay with negative charges, so that the anti-mud effect is achieved. And (3) sulfonating and quaternizing sulfonated wood/sulfonated cellulose, wherein an ester group and a quaternary ammonium group are subjected to hydrolysis reaction in an alkaline cement environment to generate a carboxyl group with negative charges and an amino group with positive charges, and the carboxyl group and the amino group have dispersing and adsorbing effects on clay with negative charges respectively, so that the mud resistance effect is achieved.

Unsaturated itaconic acid containing two carboxyl groups used in the synthesis of the polycarboxylate superplasticizer, maleic acid and maleic anhydride small monomer are copolymerized, the generated polyitaconic acid and the carboxyl groups on the side chain of the polymaleic acid macromonomer far away from the main chain can well perform esterification reaction with the active hydroxyl groups in the lignin and cellulose structures which are not hydrolyzed but separated, the lignin and the cellulose with macromolecular structures are used as the polyitaconic acid and the polymaleic acid macromonomer end sealing groups, the physical size of the tail end of the side chain is greatly increased, the physical size of the tail end of the polycarboxylate superplasticizer side chain is further improved, the polycarboxylate superplasticizer is not easy to insert into the layered structure of clay, the mud resistance effect is achieved, and the working performance of concrete is ensured.

Similarly, the lignin and cellulose with macromolecular structure have more active hydroxyl groups, such as 3 hydroxyl groups on each glucose monomer in the cellulose structure, and more active hydroxyl groups in the lignin structure. Therefore, excessive macromolecular carboxylic acids such as palmitic acid, stearic acid, benzoic acid and terephthalic acid used in the raw material pretreatment can be used as macromonomer end-capping groups of lignin and cellulose with macromolecular structures, the physical size of the tail end is further greatly increased, and the mud resistance effect is further enhanced.

And a small amount of beta-cyclodextrin is added to further improve the mud resistance and the coagulation slowing effect.

(6) A small amount of dimethyl fumarate is added, so that a good anticorrosion effect is kept on the prepared straw-based water reducing agent, the performance of the water reducing agent is kept stable for 3-5 months, and the phenomenon of decomposition and deterioration is basically avoided.

(7) In conclusion, the invention prepares the anti-mud-retarding polycarboxylate superplasticizer product by modifying the straws, not only overcomes the defect of high cost of the existing polycarboxylate superplasticizer, but also improves the application range of the anti-mud-retarding polycarboxylate superplasticizer, overcomes the limitations of the polycarboxylate superplasticizer on clay sensitivity and concrete sand and stone, shows better economic benefit and environmental protection benefit, and has potential industrial value and application prospect.

Drawings

FIG. 1-scheme for the Synthesis of the Water reducing agent of the present invention

FIG. 2 is a schematic diagram of the molecular structure of sodium lignosulfonate of the present invention

FIG. 3-schematic diagram of molecular structure of straw cellulose sulfate

FIG. 4-schematic representation of the molecular structure of quaternized sodium lignosulfonate

FIG. 5-schematic representation of the molecular Structure of quaternized cellulose sulfate

FIG. 6 is a schematic view of a molecular structure of a representative polycarboxylic acid water reducing agent in example 3 of the present invention

FIG. 7-arrangement of the system of equipment used in the invention

Detailed Description

The process equipment and the system for realizing the invention are shown in figure 7;

arrange from left to right in proper order and install on equipment support 1: the straw primary crushing device 2 and the used raw material straw bundle 3 are placed on a platform, then the raw material enters a 1# straw coarse material conveying air duct 4, a cleaning device 5 and a pre-drying device 6, then enters a spiral dryer 9 and a collecting bin 10 through a coarse material conveying belt 7, then enters a secondary crushing device 12 and a horizontal ball-milling micro-crusher 13 through a 2# straw coarse material conveying air duct 11 for crushing, then enters a 1# buffer storage tank 16 and a 1# collecting bin weighing device 15 through a 1# powder conveying belt 14, then enters a 1# batching storage tank group 18 through a 2# powder conveying belt 17, enters a 2# batching storage tank group 25 through a 3# powder conveying belt 21 after being heated and hydrolyzed by a 1# heater 20 through a spiral extrusion hydrolyzing machine 19, then enters a 2# buffer storage tank 23 through a 2# powder collecting bin weighing device 22, then enters a 2# batching storage tank group 25 through a 4# powder conveying belt 24, then enters a 3# batching storage tank 27 after being chemically reacted in a spiral extrusion reacting unit 26, heated by a No. 2 heater 28, weighed by a No. 3 aggregate bin weighing device 29, and then fed into a mixing reactor 30, heated by a No. 3 heater 31, and reacted for a certain time to obtain the required product.

Specific examples are listed below:

firstly, the characteristics of the straw raw material required by the embodiment are explained for illustration.

The straw raw materials used in the following examples are wheat straw and corn straw harvested in the Tianshui area of Gansu province in 2017, cotton straw harvested in Xinjiang, the harvested straws are air-dried, the dried straws (including roots, stems and leaves) are crushed and ground to obtain fine powder, and the fine powder is subjected to composition content analysis and detection of lignin, hemicellulose, cellulose and the like, and the analysis results are shown in the following table 1 (in terms of dry substances, mass fraction%);

TABLE 1 analysis and detection data of straw composition content

(dry basis mass%)