Improved polycarboxylic acid water reducing agent, and preparation method and application thereof

Abstract

The application discloses a preparation method of an improved polycarboxylic water reducing agent, which comprises the following steps: S1, unsaturated fluorine-containing POSS, unsaturated acid, unsaturated amine and unsaturated long-chain oxyethylene group-containing phosphate are weighed according to weight parts and are added into a reaction container; S2, a catalyst and an initiator are added; under the protection of nitrogen, the reaction system is heated to a certain temperature and is kept for a period of time, so that addition copolymerization reactions of the raw materials are caused to occur; and S3, after the copolymerization reactions are completed, the reaction liquid is cooled and separated, so that the improved polycarboxylic water reducing agent is obtained. The improved polycarboxylic water reducing agent prepared by the method has excellent water reducing effect, and simultaneously endows the concrete with excellent anti-freezing, anti-permeation and anti-chloride ion erosion performances, so that the workability and durability of the concrete of a sea building are remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water reducing agent, and particularly to an improved polycarboxylate superplasticizer and a preparation method thereof. BACKGROUND

[0002] In the field of marine construction, concrete structures face a series of unique challenges, including the impact of harsh marine environments on concrete durability. Traditional polycarboxylate superplasticizers, while excellent in improving concrete workability, still have some limitations in marine concrete applications, especially in terms of water-reducing effect, frost resistance, impermeability, and resistance to chloride ion erosion.

[0003] Chloride ion erosion is one of the main reasons for the damage of marine concrete structures. Chloride ions can penetrate into concrete and reach the surface of steel bars, causing steel corrosion and leading to structural deterioration. In addition, low temperature and freeze-thaw cycles in marine environments also pose a threat to the stability of concrete structures. Traditional superplasticizers often cannot effectively resist these environmental factors, resulting in reduced durability and service life of concrete structures. SUMMARY

[0004] In view of the above shortcomings of the prior art, the present application provides an improved polycarboxylate superplasticizer to solve the technical problem that traditional superplasticizers cannot simultaneously achieve water-reducing effect, frost resistance, impermeability, and resistance to chloride ion erosion in marine construction concrete applications.

[0005] To achieve the above purpose, the technical solution adopted by the present application is as follows:

[0006] A preparation method of an improved polycarboxylate superplasticizer, comprising the following steps:

[0007] S1: weigh the raw materials unsaturated fluorinated POSS, unsaturated acid, unsaturated amine, and unsaturated long-chain oxyethylene phosphonate by weight parts, and add them to a reaction container;

[0008] S2: add catalyst and initiator to the reaction container of step S1; under nitrogen protection, heat the reaction system to a certain temperature and maintain for a period of time, so that the raw materials undergo addition copolymerization reaction;

[0009] S3: after the copolymerization reaction of step S2 is completed, cool the reaction liquid to room temperature; remove unreacted raw materials, catalyst, and impurities by separation method to obtain the improved polycarboxylate superplasticizer.

[0010] As a preferred technical scheme, the synthesis method of the unsaturated fluorine-containing POSS is: taking fluorine-containing trichlorosilane as raw material, performing partial hydrolysis in an aqueous acetone solution to obtain a T7(OH)3 intermediate (i.e., the POSS has one unclosed corner, and three hydroxyl groups are respectively arranged at the corner); then adding unsaturated olefin trichlorosilane into the intermediate, and performing ring closure reaction under the action of triethylamine to obtain the unsaturated fluorine-containing POSS (i.e., a monofunctional POSS, wherein one functional group connected to a silicon atom of the POSS is an unsaturated olefin, and the other seven functional groups connected to the silicon atom of the POSS are fluorine-containing alkane groups).

[0011] As a preferred technical scheme, the fluorine-containing trichlorosilane is trifluoropropyl trichlorosilane and / or nonafluorohexyl trichlorosilane.

[0012] As a preferred technical scheme, the unsaturated olefin trichlorosilane is at least one of allyl trichlorosilane, 3-(trichlorosilyl)propyl methacrylate, (3-(acryloyloxy)propyl)trichlorosilane and 7-octenyl trichlorosilane.

[0013] As a preferred technical scheme, the unsaturated acid is at least one of acrylic acid, methacrylic acid, maleic acid and fumaric acid.

[0014] As a preferred technical scheme, the unsaturated amine consists of allylamine and N-vinylhexamethyleneimine.

[0015] As a preferred technical scheme, the unsaturated long-chain oxyethylene phosphonate is polyethylene glycol methacrylate phosphonate or a metal salt of polyethylene glycol methacrylate phosphonate.

[0016] As a preferred technical scheme, the molar ratio of the unsaturated acid, the unsaturated amine, the unsaturated long-chain oxyethylene phosphonate and the unsaturated fluorine-containing POSS is 2-10:5-25:3-15:1-10.

[0017] Another aspect of the present application is to provide an improved polycarboxylic acid water reducer, wherein the polycarboxylic acid water reducer is prepared by the preparation method of the improved polycarboxylic acid water reducer.

[0018] Still another aspect of the present application is to provide an application of the improved polycarboxylic acid water reducer, wherein the raw materials of a Haibin building concrete formula are taken according to the following proportions by weight: 400-450 kg / m 3 cement, 80-100 kg / m 3 fly ash, 700-800 kg / m 3 river sand, 1100-1200 kg / m 3Gravel and 160-180 kg / m 3 Water, while adding improved polycarboxylate superplasticizer, which is 0.5%-1.5% of the weight of cement, and adding 0.5-1.5 kg / m 3 Synthetic fiber, stirring and mixing evenly, get the sea building concrete.

[0019] The core of the improved polycarboxylate superplasticizer of the application lies in its unique functional group structure. The unsaturated acid (such as acrylic acid, methacrylic acid, etc.) provides a rich carboxylic acid group for the copolymerization reaction product, which can form a stable complex with calcium ions in cement, thereby reducing the interaction force between cement particles and improving the workability of concrete.

[0020] In the preparation method of the polycarboxylate superplasticizer of the application, on the one hand, unsaturated amines (such as allylamine and N-vinyl hexamethylene amine) are used as comonomers. The introduction of these unsaturated amines provides a rich amine functional group, which plays a key role in the interaction with chloride ions, thereby enhancing the chloride ion erosion resistance of the superplasticizer by forming a stable nitrogen-chlorine complex. On the other hand, the introduction of N-vinyl hexamethylene amine provides amino functional groups for the superplasticizer. These amino functional groups can be protonated in an alkaline environment to form a positive charge, which is attracted to the negative charge on the surface of the cement particles, further improving the dispersibility and stability of the superplasticizer.

[0021] The synthesized unsaturated fluorine-containing POSS has good low-temperature stability. The introduction of unsaturated fluorine-containing POSS makes the polycarboxylate superplasticizer of the application contain a rich group of elements such as fluorine and silicon, which endows the improved polycarboxylate superplasticizer with excellent frost resistance. Due to the presence of these groups, the freezing point of concrete is reduced, thereby reducing the potential damage of water ice expansion to the structure of concrete. In cold conditions, this superplasticizer can effectively prevent cracking and damage of concrete due to water ice, and enhance the durability of the concrete structure. At the same time, it has a unique cage structure, so that the branched chain with steric hindrance effect of the polycarboxylate superplasticizer of the application can occupy the pores in the concrete, further reducing the porosity and improving the compactness and impermeability of the concrete. These characteristics work together to make the concrete better resist the invasion of water and harmful substances, thereby significantly prolonging the service life of the concrete structure.

[0022] Finally, the introduction of unsaturated long-chain oxyethylene phosphate ester (such as polyethylene glycol methacrylate phosphate ester or its metal salt) into the water reducing agent brings phosphoric acid groups and long-chain oxyethylene groups. The phosphoric acid groups can form stable calcium phosphate complexes with calcium ions in cement, improving the compactness and durability of the concrete. The long-chain oxyethylene groups have good lubricity and dispersibility, and can form a stable adsorption layer on the surface of cement particles, effectively reducing the friction and cohesion between cement particles, thereby achieving significant water-reducing effect, and further improving the frost resistance, impermeability and chloride ion resistance of the concrete.

[0023] Advantages of the present application:

[0024] The improved polycarboxylic acid water reducing agent prepared by the present application not only has excellent water-reducing effect, but also endows the concrete with excellent frost resistance, impermeability and chloride ion resistance, thereby significantly improving the workability and durability of the concrete of marine structures. DETAILED DESCRIPTION

[0025] The following description is used to disclose the present application to enable those skilled in the art to implement the present application. The preferred embodiments in the following description are only as examples, and other obvious modifications can be made by those skilled in the art.

[0026] Example 1

[0027] The preparation method of the improved polycarboxylic acid water reducing agent of the present embodiment comprises the following steps:

[0028] S1: The raw materials unsaturated fluorine-containing POSS, acrylic acid, allylamine, N-vinyl hexamethylene amine and polyethylene glycol methacrylic acid phosphate ester are weighed by weight parts and added into a reaction container; the molar ratio of the unsaturated fluorine-containing POSS, acrylic acid, allylamine, N-vinyl hexamethylene amine and polyethylene glycol methacrylic acid phosphate ester is 2:4:1:3:1.

[0029] S2: To the reaction container of step S1, 0.3% and 0.2% of catalyst ammonium persulfate and initiator azobisisobutyronitrile by mass fraction are added; under nitrogen protection, the reaction system is heated to 90℃ and kept for 3 hours, so that the addition copolymerization of the raw materials occurs.

[0030] S3: After the completion of the copolymerization reaction of step S2, the reaction liquid is cooled to room temperature; the unreacted raw materials, catalysts and impurities are removed by separation methods such as filtration, centrifugation or distillation, to obtain the improved polycarboxylic acid water reducing agent.

[0031] The synthesis method of the unsaturated fluorine-containing POSS is as follows: taking trifluoropropyltrichlorosilane as a raw material, a T7(OH)3 intermediate is obtained by performing partial hydrolysis in a 65% mass concentration acetone aqueous solution, the mass ratio of the trifluoropropyltrichlorosilane to the acetone aqueous solution is 1:3, and the reaction temperature is controlled at 30°C; then, allyl trichlorosilane and triethylamine are added to the intermediate, the molar ratio of the allyl trichlorosilane to the intermediate is 1.1:1, the triethylamine is 2% of the weight of the intermediate, the ring-closing reaction is performed under the action of the triethylamine, the reaction temperature is controlled at 110°C, and the unsaturated fluorine-containing POSS is obtained.

[0032] In this embodiment, the improved polycarboxylic acid water reducing agent is applied to the sea building concrete, and the following raw materials are weighed according to the following proportions (per cubic meter of sea building concrete): 400 kg of cement, 80 kg of fly ash, 700 kg of river sand, 1100 kg of gravel and 160 kg of water, and the improved polycarboxylic acid water reducing agent is added, the improved polycarboxylic acid water reducing agent is 0.5% of the weight of the cement, and 0.5 kg of synthetic fiber is additionally added, and the mixture is stirred and mixed uniformly to obtain the sea building concrete.

[0033] Embodiment 2

[0034] In this embodiment, the improved polycarboxylic acid water reducing agent is prepared by the following steps:

[0035] S1: raw materials of unsaturated fluorine-containing POSS, methacrylic acid, allylamine, N-vinyl hexamethylene amine and polyethylene glycol methacrylic acid phosphate are weighed according to the proportions by weight and added to a reaction container; the molar ratio of the unsaturated fluorine-containing POSS, methacrylic acid, allylamine, N-vinyl hexamethylene amine and polyethylene glycol methacrylic acid phosphate is 5:10:5:10:5.

[0036] S2: catalyst ammonium persulfate and initiator azobisisobutyronitrile are added to the reaction container of step S1, and the mass proportions of the two are 0.3% and 0.2% respectively; under the protection of nitrogen, the reaction system is heated to 90°C and kept for 3 hours, so that the raw materials undergo addition copolymerization reaction.

[0037] S3: after the copolymerization reaction of step S2 is completed, the reaction liquid is cooled to room temperature; the unreacted raw materials, catalyst and impurities are removed by separation methods such as filtration, centrifugation or distillation to obtain the improved polycarboxylic acid water reducing agent.

[0038] The synthesis method of the unsaturated fluorine-containing POSS is as follows: nonafluorohexyltrichlorosilane is used as a raw material, and partial hydrolysis is carried out in an acetone aqueous solution with a mass concentration of 65% to obtain a T7(OH)3 intermediate, wherein the mass ratio of the nonafluorohexyltrichlorosilane to the acetone aqueous solution is 1:3, and the reaction temperature is controlled at 40°C; then, 3-(trichlorosilyl)propyl methacrylate and triethylamine are added to the intermediate, wherein the molar ratio of the 3-(trichlorosilyl)propyl methacrylate to the intermediate is 1.1:1, and the triethylamine is 2% of the weight of the intermediate; a ring-closure reaction is carried out under the action of triethylamine, and the reaction temperature is controlled at 110°C to obtain the unsaturated fluorine-containing POSS.

[0039] The improved polycarboxylate water reducer of this embodiment is applied to island building concrete. Specifically, the formula raw materials are weighed according to the following weight parts (per cubic meter of island building concrete): 420kg cement, 90kg fly ash, 750kg river sand, 1150kg gravel and 170kg water, and the improved polycarboxylate water reducer is added at the same time. The improved polycarboxylate water reducer is 1.0% by weight of cement. In addition, 1kg synthetic fiber is added and stirred and mixed evenly to obtain island building concrete.

[0040] Example 3

[0041] The preparation method of the improved polycarboxylate water-reducing agent of this embodiment comprises the following steps:

[0042] S1: Weigh the raw materials of unsaturated fluorine-containing POSS, maleic acid, allylamine, N-vinyl caprolactam and polyethylene glycol methacrylate phosphate in parts by weight and add them into a reaction container; the molar ratio of the unsaturated fluorine-containing POSS, maleic acid, allylamine, N-vinyl caprolactam and polyethylene glycol methacrylate phosphate is 10:15:10:15:10.

[0043] S2: Add 0.3% by weight of ammonium persulfate as a catalyst and 0.2% by weight of azobisisobutyronitrile as an initiator to the reaction vessel of step S1; under nitrogen protection, heat the reaction system to 90° C. and maintain for 3 hours to allow the raw materials to undergo addition copolymerization reaction.

[0044] S3: After the copolymerization reaction in step S2 is completed, the reaction solution is cooled to room temperature; unreacted raw materials, catalysts and impurities are removed by separation methods such as filtration, centrifugation or distillation to obtain the improved polycarboxylate water-reducing agent.

[0045] The synthesis method of the unsaturated fluorine-containing POSS is as follows: taking trifluoropropyltrichlorosilane as raw material, partial hydrolysis is carried out in 65% mass concentration of acetone aqueous solution to obtain T7(OH)3 intermediate, the mass ratio of trifluoropropyltrichlorosilane to acetone aqueous solution is 1:3, and the reaction temperature is controlled at 40°C; then (3-(acryloyloxy)propyl)trichlorosilane and triethylamine are added to the intermediate, the molar ratio of (3-(acryloyloxy)propyl)trichlorosilane to intermediate is 1.1:1, the triethylamine is 2% of the weight of the intermediate, ring closure reaction is carried out under the action of triethylamine, and the reaction temperature is controlled at 110°C to obtain the unsaturated fluorine-containing POSS.

[0046] The improved polycarboxylic acid water reducing agent is applied to the sea building concrete, and the sea building concrete is obtained by taking the following formula raw materials by weight (per cubic meter of sea building concrete): 450 kg of cement, 100 kg of fly ash, 800 kg of river sand, 1200 kg of gravel and 180 kg of water, and adding the improved polycarboxylic acid water reducing agent, which is 1.5% of the weight of the cement, and 1.5 kg of synthetic fibers.

[0047] Comparative Example 1

[0048] The polycarboxylic acid water reducing agent of the present comparative example has the same raw material composition and preparation steps as those of Example 1, except that the raw material does not contain unsaturated fluorine-containing POSS in the preparation method of the water reducing agent of the present comparative example; in addition, the sea building concrete is obtained by applying the polycarboxylic acid water reducing agent of the present comparative example.

[0049] Comparative Example 2

[0050] The polycarboxylic acid water reducing agent of the present comparative example has the same raw material composition and preparation steps as those of Example 1, except that the raw material does not contain unsaturated amine in the preparation method of the water reducing agent of the present comparative example; in addition, the sea building concrete is obtained by applying the polycarboxylic acid water reducing agent of the present comparative example.

[0051] Comparative Example 3

[0052] The polycarboxylic acid water reducing agent of the present comparative example has the same raw material composition and preparation steps as those of Example 1, except that polyethylene glycol methyl ether methacrylate is used instead of polyethylene glycol methacrylate phosphate in the preparation method of the water reducing agent of the present comparative example; in addition, the sea building concrete is obtained by applying the polycarboxylic acid water reducing agent of the present comparative example.

[0053] The improved polycarboxylic acid water reducing agents prepared in Examples 1-3 and Comparative Examples 1-3 are tested for performance, and the performance results are shown in Table 1:

[0054] Water-reducing rate and compressive strength test: First, refer to the preparation method of Examples 1 to 3 and Comparative Examples 1 to 3 to prepare a reference concrete without adding a water-reducing agent. The two kinds of concrete are respectively subjected to a slump test to calculate the water-reducing rate. The concrete added with the water-reducing agent is made into a standard size cubic test piece, and is cured under standard curing conditions for 3 days, 7 days and 28 days, and then its compressive strength is tested, and the ratio of the compressive strength after 28 days to the compressive strength of the reference concrete is used for performance evaluation.

[0055] Frost resistance test method: The concrete test piece cured for 28 days is subjected to freezing and thawing cycles at -20℃, and the number of cycles is 50, and then the loss value of the compressive strength is tested, and the frost resistance is evaluated according to the loss value.

[0056] Permeability resistance test method: According to ISO / DIS 7031 "Concrete - Test methods for permeability", the permeability coefficient of the concrete is tested to evaluate the permeability resistance.

[0057] Chloride ion erosion resistance test method: The concrete test piece cured for 28 days is partially immersed in a sodium chloride solution (simulating a seawater environment) with a mass concentration of 3.5%; after 14 days of immersion, the change in conductivity at the interface between the solution and the concrete is measured, and the penetration degree of the chloride ion is evaluated by the change in conductivity, so as to evaluate the chloride ion erosion resistance of the concrete.

[0058] Table 1

[0059] Item Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Water reduction, % 28 31 33 27 26 24 Compressive strength, % 92 93 94 85 88 90 Frost resistance, % 9 7 5 15 12 10 impermeability, 10 -12 m / s 0.8 0.6 0.5 1.0 0.9 1.2 Chloride ion penetration resistance, % 5 6 5 9 7 7

[0060] The above shows and describes the basic principles, main features and advantages of the present application. It should be understood by those skilled in the art that the present application is not limited to the above examples, and the above examples and descriptions in the specification are only the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application.

Claims

1. A method for preparing an improved polycarboxylate water-reducing agent, characterized in that: The preparation method comprises the following steps: S1: Weigh the raw materials unsaturated fluorine-containing POSS, unsaturated acid, unsaturated amine and unsaturated long-chain oxyethylene phosphate in parts by weight and add them to a reaction container; S2: Adding a catalyst and an initiator to the reaction vessel of step S1; heating the reaction system to a certain temperature under nitrogen protection and maintaining it for a period of time to allow the raw materials to undergo addition copolymerization reaction; S3: After the copolymerization reaction in step S2 is completed, the reaction solution is cooled to room temperature; unreacted raw materials, catalysts and impurities are removed by a separation method to obtain the improved polycarboxylate water reducer; The synthesis method of the unsaturated fluorine-containing POSS comprises the following steps: using fluorine-containing trichlorosilane as a raw material, partially hydrolyzing it in an acetone aqueous solution to obtain a T7(OH)3 intermediate; then adding unsaturated olefin trichlorosilane to the intermediate, and performing a ring-closure reaction under the action of triethylamine to obtain the unsaturated fluorine-containing POSS; the unsaturated amine is composed of allylamine and N-vinylcaprolactam.

2. The method for preparing the improved polycarboxylate water-reducing agent according to claim 1, wherein: The fluorine-containing trichlorosilane is trifluoropropyltrichlorosilane and / or nonafluorohexyltrichlorosilane.

3. The method for preparing the improved polycarboxylate water-reducing agent according to claim 1, wherein: The unsaturated olefin trichlorosilane is at least one of allyl trichlorosilane, 3-(trichlorosilyl)propyl methacrylate, (3-(acryloyloxy)propyl)trichlorosilane, and 7-octenyl trichlorosilane.

4. The method for preparing the improved polycarboxylate water-reducing agent according to claim 1, wherein: The unsaturated acid is at least one of acrylic acid, methacrylic acid, maleic acid and fumaric acid.

5. The method for preparing the improved polycarboxylate water-reducing agent according to claim 1, wherein: The unsaturated long-chain oxyethylene phosphate is polyethylene glycol methacrylate phosphate or a metal salt of polyethylene glycol methacrylate phosphate.

6. The method for preparing the improved polycarboxylate water-reducing agent according to claim 1, wherein: The molar ratio of the unsaturated acid, the unsaturated amine, the unsaturated long-chain oxyethylene phosphate and the unsaturated fluorine-containing POSS is 2-10:5-25:3-15:1-10.

7. An improved polycarboxylate water reducer, characterized in that: The polycarboxylate water reducer is prepared by the preparation method of the improved polycarboxylate water reducer according to any one of claims 1 to 6.

8. An application of the improved polycarboxylate water-reducing agent according to claim 7, characterized in that: Weigh the raw materials for island building concrete according to the following weight ratios: 400-450 kg / m 3 Cement, 80-100 kg / m 3 Fly ash, 700~800kg / m 3 River sand, 1100~1200kg / m 3 Crushed stone and 160~180kg / m 3 Water, add improved polycarboxylate water reducer at the same time, the improved polycarboxylate water reducer is 0.5% to 1.5% of the weight of cement, and add 0.5 to 1.5 kg / m 3 The synthetic fibers are stirred and mixed evenly to obtain island building concrete.