CN111378056B - Chitosan oligosaccharide intermediate, preparation method thereof and application of chitosan oligosaccharide intermediate in preparation of phosphonate water reducer - Google Patents
Chitosan oligosaccharide intermediate, preparation method thereof and application of chitosan oligosaccharide intermediate in preparation of phosphonate water reducer Download PDFInfo
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- CN111378056B CN111378056B CN201811651355.1A CN201811651355A CN111378056B CN 111378056 B CN111378056 B CN 111378056B CN 201811651355 A CN201811651355 A CN 201811651355A CN 111378056 B CN111378056 B CN 111378056B
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- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
- C08B37/00—Preparation of polysaccharides not provided for in groups C08B1/00 - C08B35/00; Derivatives thereof
- C08B37/0006—Homoglycans, i.e. polysaccharides having a main chain consisting of one single sugar, e.g. colominic acid
- C08B37/0024—Homoglycans, i.e. polysaccharides having a main chain consisting of one single sugar, e.g. colominic acid beta-D-Glucans; (beta-1,3)-D-Glucans, e.g. paramylon, coriolan, sclerotan, pachyman, callose, scleroglucan, schizophyllan, laminaran, lentinan or curdlan; (beta-1,6)-D-Glucans, e.g. pustulan; (beta-1,4)-D-Glucans; (beta-1,3)(beta-1,4)-D-Glucans, e.g. lichenan; Derivatives thereof
- C08B37/0027—2-Acetamido-2-deoxy-beta-glucans; Derivatives thereof
- C08B37/003—Chitin, i.e. 2-acetamido-2-deoxy-(beta-1,4)-D-glucan or N-acetyl-beta-1,4-D-glucosamine; Chitosan, i.e. deacetylated product of chitin or (beta-1,4)-D-glucosamine; Derivatives thereof
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B24/00—Use of organic materials as active ingredients for mortars, concrete or artificial stone, e.g. plasticisers
- C04B24/24—Macromolecular compounds
- C04B24/243—Phosphorus-containing polymers
- C04B24/246—Phosphorus-containing polymers containing polyether side chains
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- C07—ORGANIC CHEMISTRY
- C07H—SUGARS; DERIVATIVES THEREOF; NUCLEOSIDES; NUCLEOTIDES; NUCLEIC ACIDS
- C07H1/00—Processes for the preparation of sugar derivatives
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- C07—ORGANIC CHEMISTRY
- C07H—SUGARS; DERIVATIVES THEREOF; NUCLEOSIDES; NUCLEOTIDES; NUCLEIC ACIDS
- C07H5/00—Compounds containing saccharide radicals in which the hetero bonds to oxygen have been replaced by the same number of hetero bonds to halogen, nitrogen, sulfur, selenium, or tellurium
- C07H5/04—Compounds containing saccharide radicals in which the hetero bonds to oxygen have been replaced by the same number of hetero bonds to halogen, nitrogen, sulfur, selenium, or tellurium to nitrogen
- C07H5/06—Aminosugars
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G65/00—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule
- C08G65/02—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring
- C08G65/32—Polymers modified by chemical after-treatment
- C08G65/329—Polymers modified by chemical after-treatment with organic compounds
- C08G65/335—Polymers modified by chemical after-treatment with organic compounds containing phosphorus
- C08G65/3356—Polymers modified by chemical after-treatment with organic compounds containing phosphorus having nitrogen in addition to phosphorus
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G81/00—Macromolecular compounds obtained by interreacting polymers in the absence of monomers, e.g. block polymers
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2103/00—Function or property of ingredients for mortars, concrete or artificial stone
- C04B2103/30—Water reducers, plasticisers, air-entrainers, flow improvers
- C04B2103/302—Water reducers
Abstract
The invention provides a chitosan oligosaccharide intermediate, a preparation method thereof and application thereof in synthesizing a phosphate water reducing agent. The phosphate water reducing agent takes chitosan oligosaccharide as a main chain, phosphonic acid group adsorption groups and polyether side chains are grafted on the chitosan oligosaccharide, the main chain structure is a six-membered ring structure connected through C-O bonds, and the ring structure is provided with polyhydroxy groups. The phosphate water reducing agent has the performance of improving workability and retarding setting.
Description
Technical Field
The invention relates to a chitosan oligosaccharide intermediate, a preparation method thereof and application thereof in preparing a phosphonate water reducing agent, belonging to the field of concrete admixtures.
Background
Chitosan, also known as chitosan, is obtained by deacetylation of chitin (chitin) widely existing in nature, has a chemical name of polyglucosamine (1-4) -2-amino-B-D glucose, and is widely applied to the fields of medicine, food industry, daily chemical industry, agriculture, biotechnology, sewage treatment and the like. The molecular structure of the chitosan contains polyhydroxy and amino structures, so that more possibilities are provided for the chemical modification and research of the chitosan, and the chitosan is gradually paid attention and researched by researchers in the concrete water reducing agent industry.
Patent CN108383956A reports a preparation method of a polycarboxylic acid water reducing agent containing chitosan. Firstly, reacting an unsaturated compound containing epoxy groups with chitosan, and then synthesizing the unsaturated compound with monomers such as unsaturated carboxylic acid, unsaturated polyether and the like through free radical polymerization to obtain the target water reducing agent. Or firstly, monomers such as unsaturated compounds containing epoxy groups, unsaturated carboxylic acid, unsaturated polyether and the like are polymerized to synthesize a prepolymer through free radicals, and then chitosan is added to react with the epoxy groups in the prepolymer to prepare the target water reducing agent, and the water reducing agent has better workability improvement and slump retaining performance.
Patent CN 104356300B reports a preparation method of a modified chitosan high-efficiency retarding water reducer. The method comprises the steps of preparing double-bond-containing modified chitosan by taking chitosan and itaconic anhydride as raw materials, then carrying out free radical copolymerization on the modified chitosan and acrylic monomers, sodium allylsulfonate and the like, and finally adding a retarder into the copolymerization system to compound to obtain the modified chitosan high-efficiency retarding water reducer. Has the characteristics of high water reducing rate, strong adaptability and long retardation time.
Lei Xiping and the like (novel building materials, DOI: 10.3969/j.issn.1001-702X.2010.05.018) report a synthetic method for preparing N-maleylation water-soluble chitosan by using chitosan and maleic anhydride as raw materials and application thereof. When the water-cement ratio is 0.35, the initial fluidity of the cement paste doped with the water-soluble chitosan (the doping amount is 1 percent of the mass of the cement) is 230mm, the fluidity is reduced to 198mm after 60min, the water reduction rate is 20.4 percent, and the water reduction rate index of the common water reducing agent is reached.
The modification research of the water reducing agent mainly comprises the steps of introducing polymerizable double bonds into a chitosan structure, and synthesizing the chitosan structure into the water reducing agent by taking the chitosan structure as a comonomer through free radical polymerization. Or directly reacting the chitosan with anhydride.
However, the molecular weight of the chitosan is large, the viscosity average molecular weight of the chitosan with good water solubility is 50000-190000, the prepared water reducing agent has larger molecular weight, and the larger molecular weight is easy to cause the water solubility and the water reducing performance of the water reducing agent to slide down, so the application of the chitosan with polyhydroxy and polyamine base structures in the water reducing agent is greatly limited.
Disclosure of Invention
The invention provides a chitosan oligosaccharide intermediate which takes chitosan oligosaccharide as a raw material and has simple synthesis method and convenient structure adjustment, a phosphate water reducing agent synthesized by the intermediate, a preparation method and application thereof,
the chitosan oligosaccharide intermediate is structurally characterized in that a main chain structure is a-C-O-bonded six-membered oxygen-containing heterocyclic ring structure, the six-membered heterocyclic ring structure is provided with polyhydroxy and amino, and the amino is provided with a phosphorous acid group bridged by methylene.
The chitosan oligosaccharide intermediate is prepared from chitosan oligosaccharide, aldehyde monomers and phosphorous acid through a mannich reaction under the action of a catalyst.
The chitosan oligosaccharide is an oligosaccharide with the polymerization degree of 2-30 obtained by degrading chitosan through a biological enzyme technology, the number average molecular weight is 300-5000, and the water solubility is obviously improved compared with that of chitosan.
The phosphorous acid is solid phosphorous acid with 100 percent of solid content.
The catalyst is mainly a strong acid heterogeneous catalyst and comprises one of solid heteropoly acid, solid super acid, strong acid cation resin, nafion perfluorosulfonic acid resin and the like.
The aldehyde monomer comprises one of paraformaldehyde, 37% formaldehyde solution, glyoxylic acid and the like.
The chitosan oligosaccharide intermediate has one of the structural formulas shown as the following formula (1):
wherein x represents the number of structural units participating in phosphorylation reaction in the chitosan oligosaccharide structural unit, y represents the number of structural units not participating in phosphorylation reaction in the chitosan oligosaccharide structural unit, and x: y = (1-5): 1,x and y are integers more than 0.
The preparation method of the chitosan oligosaccharide intermediate comprises the following steps: sequentially adding chitosan oligosaccharide, water, phosphorous acid, a catalyst and an aldehyde monomer into a reaction kettle, sealing the reaction kettle after the addition is finished, starting stirring, and reacting under certain temperature and pressure conditions. After the reaction is finished, sequentially carrying out vacuum filtration and liquid alkali neutralization to obtain a chitosan oligosaccharide intermediate.
The preparation reaction of the chitosan oligosaccharide intermediate comprises the following steps: phosphorous acid: the molar ratio of the aldehyde monomer =1:x (2.0-3.0) x, the dosage of the catalyst is 5-10% of the mass of the chitosan oligosaccharide, and the dosage of the water is 40-60% of the mass of the chitosan oligosaccharide.
The preparation reaction of the chitosan oligosaccharide intermediate has the reaction temperature of 100-150 ℃, the reaction pressure of the reaction kettle and the reaction time of 5-15 h.
And (2) carrying out preparation reaction on the chitosan oligosaccharide intermediate, carrying out vacuum filtration under the vacuum degree of-0.08 to-0.1 MPa after the reaction is finished, separating the catalyst solid from the liquid of the reaction product, and then adding liquid alkali (the mass fraction is 32%) with the same molar amount as that of phosphorous acid to obtain the chitosan oligosaccharide intermediate.
The chitosan oligosaccharide intermediate can be used as an intermediate for preparing a phosphate water reducing agent.
The phosphate water reducing agent is obtained by carrying out an aminolysis reaction on a chitosan oligosaccharide intermediate and a chlorinated polyether monomer.
And (3) carrying out aminolysis reaction on the exposed amino group in the chitosan oligosaccharide intermediate and a chlorinated polyether monomer, and grafting a polyether side chain on the chitosan oligosaccharide intermediate to obtain the phosphonic acid-based water reducing agent.
The phosphate water reducing agent has the performance of improving workability and retarding setting. The chitosan oligosaccharide is used as a main chain, a phosphonic acid group adsorption group and a polyether side chain are grafted on the main chain, the main chain structure is a six-membered ring structure connected through a C-O bond, and the ring structure is provided with a polyhydroxy group. The main chain of the prepared water reducing agent not only has an electrostatic effect, but also has a steric hindrance effect in a local area, and the water reducing agent obtained by combining the steric effect of the polyether side chain has a good water reducing effect.
One of the structural formulas of the phosphonic acid-based water reducing agent is shown as the following formula (2):
the phosphonic acid water reducing agent has a weight average molecular weight of 5000-30000, and has good water solubility and performance.
The chlorinated polyether is prepared by copolymerizing an initiator, namely unsaturated alcohol ROH, and three types of alkylene oxides, namely ethylene oxide, propylene oxide and epichlorohydrin, wherein the polymerization reaction of ethylene oxide and propylene oxide in the chlorinated polyether structure is block polymerization or random polymerization, propylene oxide and ethylene oxide are polymerized firstly, or propylene oxide and ethylene oxide are polymerized simultaneously, and finally epichlorohydrin is polymerized.
The initiator R-OH is monohydric alcohol, including ethanol, butanol, isopropanol, n-amyl alcohol, cyclohexanol, benzyl alcohol, phenethyl alcohol, n-octanol, isooctanol, dodecanol, menthol, octadecanol and other small molecular alcohols with the carbon atom number of 1-20.
In the synthesis process of the chlorinated polyether, double Metal Cyanide (DMC) which can open the ring of epoxy chloropropane and does not react with chloride ions is used as a catalyst, and the dosage of the DMC catalyst is 0.01-1% of the total mass of unsaturated alcohol ROH serving as a starter. The specific polyether synthesis process is known to those skilled in the art and will not be described herein.
In the invention, the weight average molecular weight of the chlorinated polyether in the step (1) is between 400 and 5000.
The structural formula of the chlorinated polyether is shown as the following formula (3):
in the structure of the chlorinated polyether, R represents an alkyl part of an initiator ROH (unsaturated alcohol), and m represents the number of structural units of ethylene oxide in a polyether macromonomer; n represents the number of structural units of propylene oxide in the polyether macromonomer; c represents the number of structural units of epichlorohydrin in the polyether macromonomer. Wherein the number m of the structural units of the ethylene oxide is an integer between 10 and 100; in consideration of good water solubility possessed by the water reducing agent polyether, the number n of the structural units of the propylene oxide is an integer between 0 and 0.2 n.
The preparation method of the phosphonic acid-based water reducing agent comprises the following steps of: the molar ratio of the chlorinated polyether =1: y, the reaction temperature is between 100 and 150 ℃, and the reaction time is between 10 and 20 hours.
The beneficial results are that: the invention provides a preparation method of phosphonic acid water reducing agent, which has simple synthesis method, convenient structure adjustment and improved workability and slow setting performance.
Specifically, the synthesis method of the phosphonic acid-based water reducing agent disclosed by the invention has the following advantages:
the chitosan oligosaccharide is used as a main chain for the first time, a phosphonic acid group adsorption group and a polyether side chain are grafted on the chitosan oligosaccharide, the main chain structure is a six-membered ring structure connected through a C-O bond, and the ring structure is provided with a polyhydroxy group. The main chain of the prepared water reducing agent not only has an electrostatic effect, but also has a steric hindrance effect in a local area, and the water reducing agent obtained by combining the steric effect of the polyether side chain has a good water reducing effect.
The chitosan oligosaccharide contains polyhydroxy and polyamine groups in the structure, so that the chitosan oligosaccharide has good retarding and water retention effects, and the polyether side chain has a hydrophobic epoxypropane structural unit, so that the prepared water reducing agent has good effects on retarding and workability improvement besides water reducing performance.
The chitosan oligosaccharide intermediate obtained after neutralization of the phosphorylation reaction of chitosan oligosaccharide is medium-strong alkaline, and can catalyze the substitution reaction of amino in the subsequent structures of chlorinated polyether and chitosan oligosaccharide intermediate, thereby improving the reaction effect.
Firstly polymerizing propylene oxide and ethylene oxide by using DMC as a catalyst, and finally polymerizing epichlorohydrin. The inhibition effect of epoxy chloropropane on the DMC catalyst is avoided, and the synthesis efficiency of polyether is ensured to the greatest extent. In addition, waste acid and waste liquid generated by the reaction of polyether and chlorinated reagent in the traditional process for preparing chlorinated polyether are avoided.
Detailed Description
The present invention is described in detail below by way of examples, which are intended to be illustrative only and not to be construed as limiting the scope of the invention, and one skilled in the art will be able to make variations within the scope of the invention based on the disclosure herein, in reagents, catalysts and reaction process conditions. All equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.
In the examples of the present invention, the molecular weight of the polyether and the molecular weight and molecular weight distribution of the phosphonic acid based water reducing agent were determined using Wyatt technology corporation gel permeation chromatograph. (gel column: shodex SB806+803 2 chromatographic columns connected in series; eluent: tetrahydrofuran; mobile phase velocity: 1ml/min; sample amount: 20. Mu.l; sample preparation concentration: 0.5% (sample g/mobile phase g); detector: shodex RI-71 type differential refractometer detector; standard: polyethylene glycol GPC standard (Sigma-Aldrich, molecular weight 1010000,478000,263000,118000,44700,18600,6690,1960,628,232).
In the application embodiment of the invention, the adopted cement is ordinary portland cement (P.O 42.5.5), the sand is medium sand with fineness modulus Mx =2.6, and the stones are continuous graded broken stones with the particle size of 5-20 mm, except for special description. The fluidity of the cement paste is tested according to the GB/T8077-2000 standard, the water addition amount is 87g, and the fluidity of the cement paste is measured on plate glass. The test method of the gas content and the water reducing rate is executed according to the relevant regulations of GB8076-2008 concrete admixture. Slump and slump loss were carried out according to the instructions of JC473-2001, concrete Pump (concrete Pump).
The synthesis method in the embodiment is divided into two parts, namely, the preparation of the chlorinated polyether monomer, the preparation of the chitosan oligosaccharide intermediate and the synthesis of the phosphonic acid-based water reducing agent. In the embodiment, the parts are referred to as mass parts, and the addition amount of other materials is converted into mass parts.
Preparation of (mono) chloropolyether monomer M:
preparation example 1
100.0 parts of initiator ethanol is weighed, 0.02 part of catalyst DMC is added, the reaction kettle is sealed, and nitrogen is replaced for 3 times. Heating to 100 ℃, introducing 20.0 parts of propylene oxide, continuing to introduce 230.0 parts of propylene oxide after an induction reaction (temperature rise and pressure drop in the kettle), controlling the reaction temperature to be between 120 and 140 ℃, controlling the reaction pressure to be less than or equal to 0.4MPa, keeping the temperature for reaction for 10min after the material introduction is finished, then introducing 3238 parts of ethylene oxide, keeping the temperature for reaction for 10min after the material introduction is finished, finally introducing 200.0 parts of epichlorohydrin, keeping the temperature for reaction for 30min after the material introduction is finished, cooling to 80 ℃, discharging to obtain 3262 parts of colorless transparent polyether, marking as P-1, testing the number average molecular weight Mn =1035 and the molecular weight distribution PDI =1.08.
In the same way, the following chlorinated polyether monomer is prepared and used for synthesizing the ester type polycarboxylate superplasticizer.
P-2 chlorinated polyether monomer: 100.0 parts of butanol as initiator and 0.1 part of DMC, and 157.0 parts of propylene oxide, 2330.0 parts of ethylene oxide and 125.0 parts of epichlorohydrin are sequentially added to prepare 2697.0 parts of light brown yellow polyether, which is marked as P-2 and has the tested polyether number average molecular weight Mn =2021 and molecular weight distribution PDI =1.07.
P-3 chlorinated polyether monomer: 100.0 parts of phenethyl alcohol serving as an initiator and 0.5 part of DMC, and sequentially introducing 430.0 parts of propylene oxide, 3238 parts of ethylene oxide, 3238 parts of zxft And 76.0 parts of epichlorohydrin to prepare 3262 parts of light brown yellow polyether, which is marked as P-3, and the tested polyether has the number average molecular weight Mn =2981 and the molecular weight distribution PDI =1.03.
P-4 Chloropolyether monomer: 100.0 parts of isooctanol as a starter and 1.0 part of DMC, and simultaneously introducing 200.0 parts of propylene oxide, 2710.0 parts of ethylene oxide and 72.0 parts of epichlorohydrin to prepare 3075.0 parts of light brown yellow polyether, which is marked as P-4 and has the tested polyether number average molecular weight Mn =4013 and molecular weight distribution PDI =1.09.
P-5 Chloropolyether monomer: 100.0 parts of initiator dodecanol and 0.7 part of DMC, and sequentially introducing 200.0 parts of propylene oxide, 3242 parts of ethylene oxide, 2400.0 parts of epoxy chloropropane and 50.0 parts of epoxy chloropropane to prepare 2732 parts of light brown yellow polyether, wherein the light brown yellow polyether is marked as P-5, and the number average molecular weight Mn of the polyether is =4973 and the molecular weight distribution PDI is =1.06.
P-6 chlorinated polyether monomer: 100.0 parts of initiator menthol and 0.4 part of DMC, and simultaneously 100.0 parts of propylene oxide, 8978 parts of ethylene oxide, 8978 parts of zxft 8978 parts of epoxy chloropropane and 60.0 parts of epoxy chloropropane are introduced to prepare 1600 parts of light brown yellow polyether, which is marked as P-6 and has the tested polyether number average molecular weight Mn =2479 and the molecular weight distribution PDI =1.05.
P-7 chlorinated polyether monomer: 100.0 parts of octadecanol serving as an initiator and 0.3 part of DMC, and sequentially introducing 50.0 parts of propylene oxide, 380.0 parts of ethylene oxide and 35.0 parts of epichlorohydrin to prepare 555 parts of light brown yellow polyether, wherein the light brown yellow polyether is marked as P-6, the number average molecular weight Mn of the polyether is =1503, and the molecular weight distribution PDI is =1.03.
Synthesis of (di) chitosan oligosaccharide intermediate and phosphonic acid water reducing agent
Preparation example 2
Weighing 100.0 parts of chitosan oligosaccharide with the number average molecular weight Mn =483, sequentially adding 40.0 parts of solvent water, 5.0 parts of catalyst solid heteropoly acid and 67.9 parts of phosphorous acid, and starting stirring. Heating to 80 ℃, stirring until the materials are fully mixed, adding 24.8 parts of paraformaldehyde, sealing the reaction kettle, heating to 100 ℃, and carrying out heat preservation reaction for 15 hours. After the reaction, the solid heteropoly acid as the catalyst was separated by vacuum filtration, and 32% NaOH aqueous solution (103.5 parts) was added to the filtered liquid to obtain a chitooligosaccharide intermediate.
Adding 5363 parts of P-5 polyether 1029.6 into the chitosan oligosaccharide intermediate, heating to 150 ℃, and carrying out heat preservation reaction for 15h to obtain a finished product of the phosphonic acid-based water reducing agent, namely PCA-1, wherein the tested weight average molecular weight Mw of the water reducing agent =5672, and the molecular weight distribution PDI =1.34.1:2
Preparation example 3
Weighing 100.0 parts of chitosan oligosaccharide with the number average molecular weight Mn =1610, sequentially adding 50.0 parts of solvent water, 8.0 parts of catalyst solid super acid and 50.9 parts of phosphorous acid, and starting stirring. Heating to 80 ℃, stirring until the materials are fully mixed, adding 60.4 parts of 37 percent formaldehyde, sealing the reaction kettle, heating to 120 ℃, and carrying out heat preservation reaction for 10 hours. After the reaction, the solid super acid was separated by vacuum filtration, and to the filtered liquid was added 32% aqueous NaOH solution (77.6 parts) to obtain a reddish brown intermediate solution of chitosan oligosaccharide.
Adding 5363 parts of P-4 polyether 1246.3 into the chitosan oligosaccharide intermediate, heating to 130 ℃, and carrying out heat preservation reaction for 10h to obtain a brown phosphonic acid-based water reducing agent finished product, which is marked as PCA-2, and is tested to obtain a water reducing agent with the weight average molecular weight Mw =21014 and the molecular weight distribution PDI =1.58.1:1
Preparation example 4
Weighing 100.0 parts of chitosan oligosaccharide with the number average molecular weight Mn =4830, sequentially adding 60.0 parts of solvent water, 10.0 parts of catalyst strong acid cation resin NKC-9 and 76.4 parts of phosphorous acid, and starting stirring. Heating to 80 ℃, stirring until the materials are fully mixed, adding 113.3 parts of 37% formaldehyde solution, sealing the reaction kettle, heating to 150 ℃, and carrying out heat preservation reaction for 5 hours. After the reaction, the catalyst, namely the strongly acidic cationic resin NKC-9, was separated by vacuum filtration, and 32% aqueous NaOH solution 232.9 parts by weight was added to the filtered liquid to obtain a reddish chitosan oligosaccharide intermediate solution.
Adding 5363 parts of P-3 polyether 462.9 into the chitosan oligosaccharide intermediate, heating to 110 ℃, and carrying out heat preservation reaction for 17h to obtain a brown finished product of the phosphonic acid-based water reducing agent, namely PCA-3, wherein the weight average molecular weight Mw of the water reducing agent is =28793, and the molecular weight distribution PDI is =1.55.1:3
Preparation example 5
100.0 parts of chitosan oligosaccharide with the number average molecular weight Mn =3220 are weighed, 50.0 parts of solvent water, 7.0 parts of catalyst Nafion perfluorosulfonic acid resin and 76.4 parts of phosphorous acid are sequentially added, and stirring is started. Heating to 80 ℃, stirring until the materials are fully mixed, adding 34.9 parts of paraformaldehyde, sealing the reaction kettle, heating to 120 ℃, and carrying out heat preservation reaction for 15 hours. After the reaction, the catalyst Nafion perfluorosulfonic acid resin was separated by vacuum filtration, and 116.5 parts by weight of naoh aqueous solution, 32%, was added to the filtered liquid to obtain a reddish brown chitosan oligosaccharide intermediate solution.
313.8 parts of P-2 polyether is added into the chitosan oligosaccharide intermediate, the temperature is raised to 100 ℃, the reaction is carried out for 20 hours under the condition of heat preservation, and a brown phosphonic acid-based water reducing agent finished product is obtained and is marked as PCA-4, and the tested water reducing agent has the weight average molecular weight Mw =13798 and the molecular weight distribution PDI =1.59.1:4
Preparation example 6
100.0 parts of chitosan oligosaccharide with the number average molecular weight Mn =4025 is weighed, 60.0 parts of solvent water, 6.0 parts of catalyst solid heteropoly acid and 76.4 parts of phosphorous acid are sequentially added, and stirring is started. Heating to 80 ℃, stirring until the materials are fully mixed, adding 30.7 parts of paraformaldehyde, sealing the reaction kettle, heating to 140 ℃, and carrying out heat preservation reaction for 8 hours. After the reaction, the catalyst solid heteropoly acid was separated by vacuum filtration, and 32% NaOH aqueous solution 232.9 parts was added to the filtered liquid to obtain a wine-red chitosan oligosaccharide intermediate solution.
160.7 parts of P-1 polyether is added into the chitosan oligosaccharide intermediate, the temperature is raised to 120 ℃, the reaction is carried out for 13 hours under the condition of heat preservation, a tan phosphonic acid-based water reducing agent finished product is obtained, the finished product is marked as PCA-5, the weight average molecular weight Mw of the water reducing agent is =11657, and the molecular weight distribution PDI is =1.49.1:3
Preparation example 7
Weighing 100.0 parts of chitosan oligosaccharide with the number average molecular weight Mn =1932, sequentially adding 40.0 parts of solvent water, 3.0 parts of catalyst solid heteropoly acid and 84.9 parts of phosphorous acid, and starting stirring. Heating to 80 ℃, stirring until the materials are fully mixed, adding 113.3 parts of 32% formaldehyde solution, sealing the reaction kettle, heating to 120 ℃, and carrying out heat preservation reaction for 10 hours. After the reaction, the solid heteropoly acid as the catalyst was separated by vacuum filtration, and the resulting filtrate was added with 32% NaOH aqueous solution 258.8 parts to obtain a reddish chitosan oligosaccharide intermediate solution.
Adding 258.5 parts of P-6 polyether into the chitosan oligosaccharide intermediate, heating to 140 ℃, and carrying out heat preservation reaction for 16h to obtain a brown phosphonic acid-based water reducing agent finished product, which is marked as PCA-6, wherein the weight average molecular weight Mw of the water reducing agent is =7841, and the molecular weight distribution PDI is =1.52.1:5
Preparation example 8
100.0 parts of chitosan oligosaccharide with the number average molecular weight Mn =2415 is weighed, 60.0 parts of solvent water, 9.0 parts of catalyst Nafion perfluorosulfonic acid resin and 67.9 parts of phosphorous acid are sequentially added, and stirring is started. Heating to 80 ℃, stirring until the materials are fully mixed, adding 80.6 parts of 32% formaldehyde solution, sealing the reaction kettle, heating to 140 ℃, and carrying out heat preservation reaction for 13 hours. After the reaction, nafion perfluorosulfonic acid resin as a catalyst was separated by vacuum filtration, and 32% of an aqueous naoh solution 207.0 parts was added to the filtered liquid to obtain a reddish-brown chitosan oligosaccharide intermediate solution. Adding 311.2 parts of P-7 polyether into the chitosan oligosaccharide intermediate, heating to 130 ℃, and carrying out heat preservation reaction for 13h to obtain a brown phosphonic acid-based water reducing agent finished product, which is marked as PCA-7, wherein the weight average molecular weight Mw of the water reducing agent is =9786, and the molecular weight distribution PDI is =1.55.1:2
Comparative example 1
100.0 parts of chitosan oligosaccharide with the number average molecular weight Mn =1610 is weighed, 60.0 parts of solvent water, 10 parts of concentrated hydrochloric acid with the catalyst of 36.5% and 50.9 parts of phosphorous acid are sequentially added, and stirring is started. Heating to 80 ℃, stirring until the materials are fully mixed, adding 22.4 parts of paraformaldehyde, sealing the reaction kettle, heating to 170 ℃, and carrying out heat preservation reaction for 6 hours. After the reaction was completed, 155.3 parts by weight of NaOH aqueous solution was added to the filtered liquid to obtain a reddish brown chitosan oligosaccharide intermediate solution.
Adding 5363 parts of P-5 polyether 1544.4 into the chitosan oligosaccharide intermediate, heating to 120 ℃, and carrying out heat preservation reaction for 20 hours to obtain a tan phosphonic acid-based water reducing agent finished product, wherein the water reducing agent has a weight average molecular weight Mw =25792 and a molecular weight distribution PDI =1.63 through tests. 1:1
Comparative example 2
100.0 parts of polyethyleneimine with the weight-average molecular weight Mn =1800 is weighed, 60.0 parts of solvent water, 9 parts of catalyst solid heteropoly acid and 127.6 parts of phosphorous acid are sequentially added, and stirring is started. Heating to 80 ℃, stirring until the materials are fully mixed, adding 164.0 parts of 37% formaldehyde solution, sealing the reaction kettle, heating to 130 ℃, and carrying out heat preservation reaction for 12 hours. After the completion of the reaction, 32% of an aqueous NaOH solution 388.9 parts was added to the filtered liquid to obtain a reddish-brown chitosan oligosaccharide intermediate solution. 1800/43=42 1
Adding 1563.2 parts of P-2 polyether into the chitosan oligosaccharide intermediate, heating to 140 ℃, and carrying out heat preservation reaction for 15 hours to obtain a brown phosphonic acid-based water reducing agent finished product, wherein the water reducing agent has a weight average molecular weight Mw =32091 and a molecular weight distribution PDI =1.63 through tests. 1:2
The application example is as follows:
in the application examples, the cement used is ordinary portland cement (P.O 42.5.5), the sand is medium sand with fineness modulus Mx =2.6, and the stones are continuous graded broken stones with the particle size of 5-20 mm, unless otherwise specified.
Application example 1
The test of the fluidity of the cement paste is carried out according to the GB/T8077-2012 standard, 300g of ordinary portland cement is adopted, the water adding amount is 87g, and the fluidity of the cement paste is measured on plate glass. The viscosity of the initial cement paste is measured by referring to GB/T10274-2008 viscosity measurement method. The results of the neat paste test are shown in table 1.
TABLE 1 Cement paste fluidity test results
Remarking: PCA-III is a commercial ether type polycarboxylate superplasticizer product of a certain company in China.
The results in Table 1 show that the phosphonic acid-based water reducing agent prepared by using chitosan oligosaccharide as a raw material has better initial flow property and slump retaining property, the initial water reducing capacity of the water reducing agent is similar to that of the conventional ether type polycarboxylate water reducing agent PCA-III, but the slump retaining property is obviously better than that of the conventional ether type polycarboxylate water reducing agent PCA-III. In addition, during the viscosity test of the neat paste, the phosphonic acid-based water reducing agent disclosed by the invention is found to be capable of reducing the viscosity of the cement paste to a certain extent.
In comparative example 1, homogeneous catalyst inorganic acid is used for replacing heterogeneous strong acid catalyst for the phosphonic acid reaction of chitosan oligosaccharide, and the difference of the prepared water reducing agent in slump retaining performance is obvious compared with the example; in comparative example 2, the phosphonic acid-based water reducing agent prepared by using polyethyleneimine instead of chitosan oligosaccharide as a raw material has a large weight average molecular weight, and the initial water reducing and slump retaining performances of the water reducing agent are inferior to those of the examples.
Application example 2
The test method of the gas content and the water reducing rate is carried out according to the relevant regulations of GB8076-2008 concrete admixture. And the slump of the fresh concrete of the water reducer and the change of the slump over time of 60min are measured by referring to a related method of JC473-2001 concrete pumping agent, and the slump bucket emptying time of the fresh concrete is measured so as to measure the viscosity of the concrete. The concrete test results are shown in table 2.
TABLE 2 concrete test results
Remarking: PCA-III is a commercialized ether type polycarboxylate superplasticizer product of a certain company in China, and 2 drops of commercialized defoaming agent are added in each group of concrete test.
From the results in table 2, it can be seen that, under the conditions similar to the gas content of concrete, the slump bucket time of the phosphonic acid-based water reducing agent prepared from chitosan oligosaccharide is obviously shorter than that of the commercial ether-type polycarboxylic acid water reducing agent product. From concrete technical indexes such as slump/expansion degree, the phosphonic acid-based water reducing agent has better slump retaining performance under the condition of similar concrete expansion degree and slump. In conclusion, compared with the traditional ether type polycarboxylate water reducer, the phosphonic acid based water reducer prepared by taking chitosan oligosaccharide as a raw material has better slump retaining performance and workability improvement capability.
Claims (12)
1. A phosphonic acid-based water reducing agent is characterized in that a chitosan oligosaccharide intermediate is used as a main chain, polyether side chains are grafted on the main chain,
the main chain structure of the chitosan oligosaccharide intermediate is a-C-O-bonded six-membered oxygen-containing heterocyclic structure, the six-membered heterocyclic structure is provided with polyhydroxy and amino, and the amino is provided with a phosphorous acid group bridged by methylene; the chitosan oligosaccharide intermediate is prepared from chitosan oligosaccharide, aldehyde monomer and phosphorous acid through mannich reaction under the action of a catalyst;
the chitosan oligosaccharide is obtained by degrading chitosan through a biological enzyme technology, the polymerization degree of the chitosan oligosaccharide is between 2 and 30, and the number average molecular weight of the chitosan oligosaccharide is between 300 and 5000;
the phosphorous acid is solid phosphorous acid with 100 percent of solid content;
the catalyst is a strong acid heterogeneous catalyst and is selected from one of solid heteropoly acid, solid super acid, strong acid cation resin and Nafion perfluorosulfonic acid resin;
the aldehyde monomer is one selected from paraformaldehyde, 37% formaldehyde solution, glyoxylic acid and the like.
2. The phosphonic acid based water reducing agent according to claim 1, characterized in that one of the structural formulas of the chitosan oligosaccharide intermediate is represented by the following formula (1):
wherein x represents the number of structural units participating in phosphorylation reaction in the chitosan oligosaccharide structural unit, y represents the number of structural units not participating in phosphorylation reaction in the chitosan oligosaccharide structural unit, and x: y = (1-5): 1,x and y are integers more than 0.
3. The phosphonic acid-based water reducing agent according to claim 2, characterized in that the preparation steps of the chitosan oligosaccharide intermediate are as follows: sequentially adding chitosan oligosaccharide, water, phosphorous acid, a catalyst and an aldehyde monomer into a reaction kettle, sealing the reaction kettle after the addition is finished, starting stirring, wherein the reaction temperature is between 100 and 150 ℃, the reaction pressure is the pressure generated by the reaction kettle, and the reaction time is 5 to 15 hours; after the reaction is finished, sequentially carrying out vacuum filtration and liquid alkali neutralization to obtain a chitosan oligosaccharide intermediate;
the preparation reaction of the chitosan oligosaccharide intermediate comprises the following steps: phosphorous acid: the mol ratio of the aldehyde monomer =1:x (2.0-3.0) x, the dosage of the catalyst is 5% -10% of the weight of the chitosan oligosaccharide, and the dosage of the water is 40% -60% of the weight of the chitosan oligosaccharide.
4. The phosphonic acid based water reducing agent according to claim 3, characterized in that the preparation reaction of the chitosan oligosaccharide intermediate is carried out, after the reaction is finished, vacuum filtration is carried out under the vacuum degree of-0.08 to-0.1 MPa, the catalyst solid is separated from the liquid of the reaction product, and then liquid alkali with the same molar amount as that of phosphorous acid is added to obtain the chitosan oligosaccharide intermediate.
5. The phosphonic acid based water reducing agent according to any one of claims 2 to 4, characterized in that it is obtained by an aminolysis reaction of a chitooligosaccharide intermediate with a chlorinated polyether monomer; carrying out aminolysis reaction on the exposed amine group in the chitosan oligosaccharide intermediate and a chlorinated polyether monomer, and grafting a polyether side chain on the chitosan oligosaccharide intermediate to obtain the phosphonic acid-based water reducing agent;
the structural formula of the chlorinated polyether is shown as the following formula (3):
in the structure of the chlorinated polyether, R represents an alkyl part of an initiator ROH (unsaturated alcohol), and m represents the number of structural units of ethylene oxide in a polyether macromonomer; n represents the number of structural units of propylene oxide in the polyether macromonomer; c represents the number of structural units of epichlorohydrin in the polyether macromonomer; wherein the number m of structural units of the ethylene oxide is an integer between 10 and 100; in consideration of good water solubility of the polyether of the water reducing agent, the number n of the structural units of the propylene oxide is an integer between 0 and 0.2 m; and the weight average molecular weight of the chlorinated polyether is between 400 and 5000.
6. The phosphonic acid based water reducing agent according to claim 5, characterized in that the reaction temperature of the aminolysis reaction is between 100 and 150 ℃ and the reaction time is between 10 and 20 hours.
7. The phosphonic acid based water reducing agent according to claim 6, characterized in that the chlorinated polyether is prepared by copolymerizing an initiator, namely an unsaturated alcohol ROH, with three types of alkylene oxides, namely ethylene oxide, propylene oxide and epichlorohydrin, wherein the polymerization reaction of ethylene oxide and propylene oxide in the chlorinated polyether structure is block polymerization or random polymerization, and propylene oxide and ethylene oxide are polymerized first or simultaneously, and epichlorohydrin is polymerized finally;
the initiator R-OH is monohydric alcohol selected from ethanol, butanol, isopropanol, n-pentanol, cyclohexanol, benzyl alcohol, phenethyl alcohol, n-octanol, isooctanol, dodecanol, menthol and octadecanol.
8. The phosphonic acid based water reducing agent according to claim 5, characterized in that during the synthesis of said chlorinated polyether, a Double Metal Cyanide (DMC) capable of ring opening of epichlorohydrin and not reacting with chloride ions is used as catalyst, and the amount of DMC catalyst is between 0.01% and 1% of the total mass of starter unsaturated alcohol ROH.
9. The phosphonic acid based water reducing agent of claim 5, characterized in that one of the structural formulas of the phosphonic acid based water reducing agent is represented by the following formula (2):
10. the phosphonic acid based water reducer according to any of claims 6-8, characterized in that one of the structural formulas of the phosphonic acid based water reducer is represented by the following formula (2):
11. the phosphonic acid based water reducer of claim 5, characterized in that the phosphonic acid based water reducer has a weight average molecular weight between 5000 and 30000.
12. The phosphonic acid based water reducer according to any of claims 6-8 characterized in that the phosphonic acid based water reducer has a weight average molecular weight between 5000 and 30000.
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