CN104356300B - Efficient retardation water reducing agent of a kind of modification of chitosan and preparation method thereof and using method - Google Patents

Abstract

The present invention discloses efficient retardation water reducing agent of a kind of modification of chitosan and preparation method thereof and using method, modification of chitosan containing double bond is prepared with furoate clothing anhydride reactant with shitosan, gained modification of chitosan carries out copolymerization again with acrylic monomer and sodium allylsulfonate, and products therefrom carries out compounding with retarder and obtained the efficient retardation water reducing agent of modification of chitosan.The features such as water reducer prepared by the inventive method is had diminishing efficiency high, strong adaptability, Slow setting time length and can be used cooperatively with poly carboxylic acid series water reducer.

Description

A modified chitosan high-efficiency retarding water reducer and its preparation method and use method

【Technical field】

The invention relates to the field of water reducing agents for concrete, in particular to a modified chitosan high-efficiency retarding water reducing agent and its preparation method and use method.

【Background technique】

Water reducer is an important admixture that must be used in the production and construction of modern concrete. The development of water reducers has experienced the first generation of lignosulfonate water reducers, the second generation of naphthalene sulfonate and sulfamate water reducers, and the third generation of polycarboxylate water reducers. At present, the second-generation water-reducer is the most widely used in China, and the third-generation polycarboxylate-based water-reducer is still being promoted, and its usage is increasing year by year. When the second-generation naphthalene-based water reducer is used, its solid content is about 1% of the cement weight, the water reducing rate can reach 15% to 20%, and the retarding time is 1 to 2 hours. The third-generation polycarboxylate water reducer has a solid content of 0.2% of the cement weight, a water reducing rate of about 30%, and a retarding time of 2 to 3 hours. At present, the problem encountered in the application of the third-generation water reducing agent is that it has poor adaptability and is sensitive to the variety of cement and the mud content in sand and gravel. It has good adaptability when used in some brands of cement, but in use For other brands of cement, the effect may be very poor. At the same time, when the mud content in the sand is greater than 5%, the water-reducing rate of the polycarboxylate-based water-reducing agent and the fluidity of the concrete will drop significantly, making it almost unusable. , The existence of these problems hinders the popularization and application of polycarboxylate superplasticizers in central my country, especially in Northwest China. The reason is that the natural sand of the river courses in these areas generally has a high mud content. The sensitivity of polycarboxylate superplasticizers to the mud content of sand has become a research hotspot in recent years.

【Content of invention】

The object of the present invention is to provide a modified chitosan high-efficiency retarding water-reducer and its preparation method and use method. The modified chitosan high-efficiency retarding water-reducer prepared by the method has high water-reducing efficiency.

In order to achieve the above object, the present invention adopts the following technical solutions:

A preparation method of a modified chitosan high-efficiency retarding water reducer, comprising the following steps:

According to parts by weight, heat 15-20 parts of chitosan and 8-12 parts of itaconic anhydride in a dry, anhydrous reactor to 70-80°C, stir and mix evenly, and then heat up to 90-95°C to continue the heat preservation reaction for 2~ After 3 hours, after cooling down to 40-50°C, add 40-50 parts of deionized water under stirring, then neutralize until the pH value is 6.5-7.5, keep the temperature of the obtained product solution at 45-50°C, and add dropwise under stirring 8 to 12 parts of mixed monomers, 2 to 4 parts of initiator solution I and 1.5 to 3.5 parts of initiator solution II, the dropping time is 1 to 1.5 hours. 25-30°C, then neutralize until the pH value is 6.5-7.5, then add 3-5 parts of retarder, and stir evenly to obtain a modified chitosan high-efficiency retarded superplasticizer.

Preferably, the deacetylation degree of the chitosan is greater than 85%, the viscosity is 350mPa.s-250mPa.s, and it can be dissolved in water.

Preferably, the mixed monomers are prepared by mixing acrylic acid, methacrylic acid, sodium allyl sulfonate and water in parts by weight of 10:2:1:5.

Preferably, the initiator solution I is obtained by dissolving ammonium persulfate, potassium persulfate or sodium persulfate in water, wherein the mass ratio of ammonium persulfate, potassium persulfate, sodium persulfate to water is 1:10; Agent solution II is obtained by dissolving sodium bisulfite, sodium sulfite or sodium thiosulfate in water, wherein the mass ratio of sodium bisulfite, sodium sulfite, sodium thiosulfate to water is 1:10; the adding method of initiator is initiator Solution I and initiator solution II were added dropwise without mixing before adding.

Preferably, the retarder is sodium citrate, sodium gluconate or sodium tripolyphosphate.

Preferably, the time for stirring the chitosan and itaconic anhydride uniformly is 30-50 minutes.

Preferably, a 40% sodium hydroxide solution is used to adjust the pH value.

The use method of modified chitosan high-efficiency retarded water-reducer: the water-reducing rate of the modified chitosan high-efficiency retarded water-reducer is 0.4% of the cement weight, and the water-reducing rate is 27-30%, which can be used for sand Concrete with stone mud content less than 11%.

How to use modified chitosan high-efficiency retarding water reducer: when using, add 0.12% to 0.15% of modified chitosan water reducer and 0.12% to 0.16% of cement weight into cement Carboxylic acid-based water reducer, with a water reducing rate of 28% to 30%, can be used for concrete with sand and gravel mud content less than 9%.

Compared with the prior art, the present invention has the following beneficial effects: the present invention adopts the reaction of chitosan and itaconic anhydride to prepare modified chitosan containing double bonds, and the gained modified chitosan is combined with acrylic monomer and allyl base sulfonate etc. for free radical polymerization, and finally compound with sodium citrate and other retarders to prepare modified chitosan high school water reducer; the water reducer prepared by the method of the present invention has high water reducing efficiency, and when solid The water-reducing rate is 27-30% when the cement weight is 0.4%. It has good adaptability to cement and has a long retarding time. The retarding time alone can reach 4-5 hours. 11% concrete. At the same time, this product can also be used in conjunction with polycarboxylate superplasticizers, which can improve the defects of easy bleeding, segregation, and sensitivity to mud and sand in polycarboxylate superplasticizers. The solid content is 0.12% to 0.16% according to the weight of cement, and the solid content is 0.12% to 0.15% according to the weight of cement. Using this product together, the water reduction rate is 28% to 30%, which can prevent the concrete from being damaged during the mixing construction process. Applicable to concrete with less than 9% sand and gravel mud content.

【detailed description】

A kind of preparation method of modified chitosan high-efficiency retarding superplasticizer of the present invention comprises the following steps:

Heat 15-20 parts of chitosan and 8-12 parts of itaconic anhydride in a dry, anhydrous reactor to 70-80°C and stir for 30-50 minutes, then heat up to 90-95°C to keep warm React for 2 to 3 hours, after cooling down to 40 to 50°C, slowly add 40 to 50 parts of deionized water under stirring, neutralize with 40% sodium hydroxide solution to a pH value of 6.5 to 7.5, and obtain a product solution Keep the temperature at 45-50°C, add 8-12 parts of mixed monomers, 2-4 parts of initiator solution I and 1.5-3.5 parts of initiator solution II dropwise under stirring, and the dropping time is 1-1.5 hours. After the feeding is completed, continue the heat preservation reaction for 4 to 5 hours, then cool down to 25 to 30°C, neutralize with 40% sodium hydroxide solution to a pH value of 6.5 to 7.5, then add 3 to 5 parts of retarder, and stir The modified chitosan high-efficiency retarding superplasticizer was evenly obtained.

The degree of deacetylation of the chitosan is greater than 85%, the viscosity is 350mPa.s-250mPa.s, and it is soluble in water.

The aforementioned mixed monomers are prepared by mixing acrylic acid, methacrylic acid, sodium allyl sulfonate and water in parts by weight of 10:2:1:5.

The above initiator I is obtained by dissolving 1 part of ammonium persulfate, 1 part of potassium persulfate or 1 part of sodium persulfate in 10 parts of water; initiator II is obtained by dissolving 1 part of sodium bisulfite, 1 part of sodium sulfite or 1 part of sodium thiosulfate It is obtained by dissolving in 10 parts of water; the way of adding the initiator is to add the initiator I and the initiator II dropwise respectively, and do not mix them before adding.

The above-mentioned set retarder is sodium citrate, sodium gluconate or sodium tripolyphosphate.

Example 1

A preparation method of a modified chitosan high-efficiency retarding water reducer, comprising the following steps: heating 15 parts of chitosan and 12 parts of itaconic anhydride in a dry, anhydrous reactor to 80° C. and stirring Mix for 30 minutes, then raise the temperature to 90°C and continue the heat preservation reaction for 2 hours, then slowly add 40 parts of deionized water under stirring after cooling down to 40°C, neutralize with a mass fraction of 40% sodium hydroxide solution until the pH value is 6.5, The resulting product solution was kept at a temperature of 45°C, and 8 parts of mixed monomers, 2 parts of initiator solution I (obtained by dissolving ammonium persulfate in water, the mass ratio of ammonium persulfate to water was 1:10) and 3.5 parts of initiator solution II (obtained by dissolving sodium sulfite in water, the mass ratio of sodium sulfite to water is 1:10), the dropwise addition time is 1 hour, after the addition is completed, continue the insulation reaction for 4 hours, then cool down to 25 ° C, use mass The fraction is 40% sodium hydroxide solution to neutralize to a pH value of 6.5, then add 5 parts of sodium citrate as a retarder, and stir evenly to obtain a modified chitosan high-efficiency retarder superplasticizer.

Example 2

A preparation method of a modified chitosan high-efficiency retarding water reducer, comprising the following steps: heating 18 parts of chitosan and 8 parts of itaconic anhydride in a dry, anhydrous reactor to 70° C. and stirring Mix for 50 minutes, then raise the temperature to 95°C and continue the heat preservation reaction for 3 hours, then slowly add 50 parts of deionized water under stirring after cooling down to 40°C, neutralize with a mass fraction of 40% sodium hydroxide solution until the pH value is 7.5, The resulting product solution was maintained at a temperature of 50°C, and 10 parts of mixed monomers, 2 parts of initiator solution I (obtained by dissolving potassium persulfate in water, the mass ratio of potassium persulfate to water was 1:10) and 2.5 parts of initiator solution II (obtained by dissolving sodium thiosulfate in water, the mass ratio of sodium thiosulfate to water is 1:10), the dropwise addition time is 1 hour, after the addition is completed, continue the insulation reaction for 4 hours, then cool down to 30°C, neutralize with 40% sodium hydroxide solution to a pH value of 7.5, then add 4 parts of sodium citrate as a retarder, and stir evenly to obtain a modified chitosan high-efficiency retarded superplasticizer.

Example 3

A preparation method of a modified chitosan high-efficiency retarding water reducer, comprising the following steps: heating 20 parts of chitosan and 10 parts of itaconic anhydride in a dry, anhydrous reactor to 70° C. and stirring Mix for 50 minutes, then raise the temperature to 95°C and continue the heat preservation reaction for 2 hours, then slowly add 50 parts of deionized water under stirring after cooling down to 40°C, neutralize with a mass fraction of 40% sodium hydroxide solution until the pH value is 7.5, The resulting product solution was maintained at a temperature of 50°C, and 12 parts of mixed monomers, 2 parts of initiator solution I (obtained by dissolving potassium persulfate in water, the mass ratio of potassium persulfate to water was 1:10) and 1.5 parts of initiator solution II (obtained by dissolving sodium sulfite in water, the mass ratio of sodium sulfite to water is 1:10), the dropwise addition time is 1.5 hours, after the addition is completed, continue the insulation reaction for 5 hours, then cool down to 25 ° C, use mass The fraction is 40% sodium hydroxide solution to neutralize to a pH value of 7.5, then add 3 parts of sodium gluconate as a retarder, and stir evenly to obtain a modified chitosan high-efficiency retarder superplasticizer.

Example 4

A preparation method of a modified chitosan high-efficiency retarding water reducer, comprising the following steps: heating 16 parts of chitosan and 11 parts of itaconic anhydride in a dry, anhydrous reactor to 80° C. and stirring according to parts by weight Mix for 30 minutes, then raise the temperature to 90°C and continue the heat preservation reaction for 2 hours, then slowly add 45 parts of deionized water under stirring after cooling down to 50°C, neutralize with a mass fraction of 40% sodium hydroxide solution until the pH value is 7, The resulting product solution was kept at a temperature of 50°C, and 10 parts of mixed monomers, 2 parts of initiator solution I (obtained by dissolving sodium persulfate in water, the mass ratio of sodium persulfate to water was 1:10) and 1.5 parts of initiator solution II (obtained by dissolving sodium bisulfite in water, the mass ratio of sodium bisulfite to water is 1:10), the dropwise addition time is 1.5 hours, after the addition is completed, continue the insulation reaction for 5 hours, and then cool down to 30°C, neutralize with 40% sodium hydroxide solution to a pH of 7.5, then add 3 parts of sodium tripolyphosphate as a retarder, and stir evenly to obtain a modified chitosan high-efficiency retarded superplasticizer .

Example 5

A preparation method of a modified chitosan high-efficiency retarding water reducer, comprising the following steps: heating 15 parts of chitosan and 12 parts of itaconic anhydride in a dry, anhydrous reactor to 70° C. and stirring Mix for 40 minutes, then raise the temperature to 95°C and continue the heat preservation reaction for 3 hours, then slowly add 50 parts of deionized water under stirring after cooling down to 40°C, neutralize with a mass fraction of 40% sodium hydroxide solution until the pH value is 7.5, The resulting product solution was kept at a temperature of 50°C, and 12 parts of mixed monomers, 2 parts of initiator solution I (obtained by dissolving ammonium persulfate in water, the mass ratio of ammonium persulfate to water was 1:10) and 1.5 parts of initiator solution II (obtained by dissolving sodium bisulfite in water, the mass ratio of sodium bisulfite to water is 1:10), the dropwise addition time is 1 hour, after the addition is completed, continue the insulation reaction for 4 hours, and then lower the temperature to 30°C, neutralize with 40% sodium hydroxide solution to pH 7.5, then add 5 parts of sodium gluconate as a retarder, and stir evenly to obtain a modified chitosan high-efficiency retarded superplasticizer.

The present invention adopts the reaction of chitosan and itaconic anhydride to prepare modified chitosan containing double bonds, and then carries out free radical polymerization reaction with acrylic monomer and allyl sulfonate etc. The coagulant is compounded to prepare a modified chitosan high-school water-reducing agent; the water-reducing agent prepared by the method of the present invention has a high water-reducing efficiency, and when the solid content is 0.4% of the cement weight, the water-reducing rate is 27-30%. Good adaptability to cement, suitable for concrete with less than 11% mud content in sand and gravel, long retarding time, the retarding time can reach 5 hours. At the same time, this product can be used in conjunction with polycarboxylate superplasticizers, which can improve the defects of easy bleeding, segregation, and sensitivity to mud and sand in polycarboxylate superplasticizers. The solid content is 0.12% to 0.16% of the weight of the cement. At the same time, according to the solid content of 0.12% to 0.15% of the cement weight, this product can be used together to prevent the phenomenon of water leakage and segregation of the concrete during the mixing construction process, and reduce water. The ratio is 28% to 30%, which is suitable for concrete with sand and gravel mud content less than 9%.

Claims (7)

1. the preparation method of the efficient retardation water reducing agent of a kind of modification of chitosan, it is characterised in that comprise the following steps：

15 ~ 20 parts of shitosan and 8 ~ 12 parts of furoate clothing acid anhydrides are heated to into 70 being dried, in anhydrous reactor according to weight portion ~ 80 DEG C are uniformly mixed, and are then warmed up to 90 ~ 95 DEG C and continue insulation reaction 2 ~ 3 hours, add after being down to 40 ~ 50 DEG C under agitation Enter 40 ~ 50 parts of deionized waters, it is 6.5 ~ 7.5 to be then neutralized to pH value, and products therefrom solution keeping temperature is 45 ~ 50 DEG C, is being stirred Mix the initiator solution II of lower 8 ~ 12 parts of mix monomers of Deca respectively, 2 ~ 4 parts of initiator solution I and 1.5 ~ 3.5 parts, time for adding For 1 ~ 1.5 hour, charging finished follow-up continuous insulation reaction 4 ~ 5 hours, then cools to 25 ~ 30 DEG C, and being then neutralized to pH value is 6.5 ~ 7.5,3 ~ 5 parts of retarder are subsequently adding, the efficient retardation water reducing agent of modification of chitosan has been uniformly mixing to obtain；

The deacetylation of the shitosan is more than 85%, and viscosity is 350mPa.s ~ 250mPa.s, can be dissolved in water；

The mix monomer is by acrylic acid, methacrylic acid, sodium allylsulfonate and water according to weight portion 10:2:1:5 mixing and Into；

The initiator solution I is dissolved in the water by Ammonium persulfate., potassium peroxydisulfate or sodium peroxydisulfate and is obtained, wherein persulfuric acid The mass ratio of ammonium, potassium peroxydisulfate, sodium peroxydisulfate and water is 1:10；Initiator solution II by sodium sulfite, sodium sulfite or Person's sodium thiosulfate is dissolved in the water and obtains, and wherein the mass ratio of sodium sulfite, sodium sulfite, sodium thiosulfate and water is 1: 10；The feed postition of initiator is initiator solution I and initiator solution II difference Deca, is not mixed before adding.

2. the preparation method of the efficient retardation water reducing agent of a kind of modification of chitosan according to claim 1, it is characterised in that：Institute Retarder is stated for sodium citrate, sodium gluconate or sodium tripolyphosphate.

3. the preparation method of the efficient retardation water reducing agent of a kind of modification of chitosan according to claim 1, it is characterised in that：Shell The time that polysaccharide and furoate clothing acid anhydride stir is 30 ~ 50 minutes.

4. the preparation method of the efficient retardation water reducing agent of a kind of modification of chitosan according to claim 1, it is characterised in that：Adopt It is that 40% sodium hydroxide solution adjusts pH value with mass fraction.

5. prepared by a kind of preparation method of the efficient retardation water reducing agent of modification of chitosan any one of Claims 1-4 The efficient retardation water reducing agent of modification of chitosan.

6. the using method of the efficient retardation water reducing agent of modification of chitosan described in claim 5, it is characterised in that be used in sandstone When clay content is less than in 11% concrete, the solids loading content of the efficient retardation water reducing agent of the modification of chitosan is cement weight When 0.4%, 27% ~ 30%, Slow setting time was up to 4 ~ 5 hours for water-reducing rate.

7. the using method of the efficient retardation water reducing agent of modification of chitosan described in claim 5, it is characterised in that be used in sandstone When clay content is less than in 9% concrete, efficiently delayed using modification of chitosan of the solid volume for cement weight 0.12% ~ 0.15% Solidifying water reducer and 0.12% ~ 0.16% poly carboxylic acid series water reducer, water-reducing rate be 28% ~ 30%, Slow setting time be 4 ~ 5 hours.