Methacrylic acid monosilane ester and preparation method thereof, compound water reducing agent and preparation method thereof

Abstract

This invention relates to the field of compound synthesis, and particularly to monosilane methacrylate and its preparation method, as well as compound water-reducing agents and their preparation methods. This invention prepares monosilane methacrylate by esterification of (meth)acrylic acid and hydroxyl-modified silicone oil under the action of a catalyst and a polymerization inhibitor. This method utilizes the hydrophobic properties of small-molecule silicone oil as a linear polymer, selecting small-molecule hydroxyl-terminated silicone oil and (meth)acrylic acid from unsaturated carboxylic acids as raw materials, and esterifying them to generate monosilane methacrylate, thus improving its hydrophilicity. The generated monosilane methacrylate is then copolymerized with unsaturated carboxylic acids to synthesize a water-reducing agent with Si-O bonds as the core, retaining the easy film-forming and high rigidity properties of long-chain siloxanes. This monosilane methacrylate is suitable for gypsum-based self-leveling mortars, exhibiting excellent water absorption, impermeability, and compressive strength, thus providing waterproofing and reinforcing effects in gypsum-based mortars.

Description

Technical Field

[0001] This invention relates to the field of compound preparation, and particularly to monosilane methacrylate and its preparation method, and compound water-reducing agent and its preparation method. Background Technology

[0002] Gypsum-based self-leveling mortar is widely used in indoor underfloor heating flooring and exterior wall decoration due to its advantages such as being lightweight, fireproof, soundproof, heat-insulating, and hardening quickly.

[0003] However, gypsum-based self-leveling mortar has many capillary pores on its surface, a low softening coefficient, and is prone to softening when exposed to water and moisture. At the same time, gypsum-based mortar dries and hardens quickly, resulting in poor volume stability. After being exposed to water or absorbing water, the compressive strength of gypsum-based self-leveling mortar is low, which affects the quality of the project and its widespread use.

[0004] In the mixing process of gypsum-based self-leveling mortar, appropriate amounts of cement and water-reducing agents are added to improve the mortar's workability, compensate for post-strengthening shrinkage, and enhance the water resistance and structural density of the hardened gypsum. However, adding cement reduces the color of the gypsum mortar base surface. Currently, the water-reducing agents added to gypsum-based self-leveling mortars are designed to address problems in concrete construction, with cement as their carrier. Their physicochemical properties differ from those of gypsum-based rapid-hardening materials, leading to numerous problems in the application of gypsum-based mortars.

[0005] Silane esters are organosilicon compounds commonly used as surface modifiers, coupling agents, or crosslinking agents, and are widely applied in plastics, rubber, coatings, adhesives, and composite materials. However, existing silane ester water-reducing agents have problems such as high water absorption, poor waterproofing (resistance), and low resistance to seepage pressure and water compressive strength when applied to gypsum-based self-leveling mortars.

[0006] In the prior art, how to prepare a water-reducing agent that is suitable for gypsum-based self-leveling mortar, has low water absorption, and excellent resistance to seepage pressure and compressive strength is a problem that needs to be solved by those skilled in the art. Summary of the Invention

[0007] To address the problems of poor water resistance, low impermeability, and low compressive strength of silane ester water-reducing agents in existing gypsum-based self-leveling mortars.

[0008] This invention provides a monosilane methacrylate as described in general formula I:

[0009] (I)

[0010] Wherein, R is alkyl, silyl or cycloalkyl, R1 is hydrogen or methyl, R2 is amino, benzene ring or hydrogen, n is 1-5, and m is 1-3.

[0011] The monosilane methacrylate provided by this invention is a homopolymer with a molecular weight of 270-660. One end of the hydroxyl group is retained. Since the hydroxyl group is a low-viscosity linear group, the synthesized monosilane methacrylate is polar and the molecule is an asymmetric polar long chain. The asymmetric molecular configuration leads to the twisting of opposite sides in molecular motion. When applied to water-reducing agents, it can improve the film-forming effect of water-reducing agents on the surface of gypsum-based mortar. With the addition of an appropriate amount of water-reducing agent, the fluidity of gypsum-based mortar can be improved.

[0012] Furthermore, this monosilane methacrylate has a Si-O bond as its core framework, compared to conventional PCE water-reducing agents which have a -CC bond as their framework. It retains the easy film-forming, high rigidity, and hydrophobic properties of long-chain siloxanes. When mixed and reacted with gypsum-based materials, it is carried into the gaps inside the gypsum-based mortar as its aqueous solution penetrates into the mortar structure. It undergoes a chelation reaction with calcium ions in the gypsum base to form water-insoluble microcrystalline particles with Si-O cores. The crystals form from sparse to dense in the gaps of the gypsum-based mortar, gradually forming a dense, impermeable zone from the surface to the depth of the gypsum-based mortar structure, thereby rapidly improving the strength of the gypsum-based mortar.

[0013] As water molecules evaporate, gypsum hardens rapidly. The hydrophobic silane chains in monosilane methacrylate remain in the pores of the gypsum mortar, layering and interlacing to form a rigid hydrophobic film between the mortar pores. This seals the micropores of the gypsum-based board, preventing the accumulation of external water molecules on the surface and their penetration into the interior of the gypsum-based board, effectively improving the water resistance (proofing) effect of the gypsum-based self-leveling mortar surface.

[0014] This invention also provides a method for preparing monosilane methacrylate, comprising the following steps:

[0015] The (meth)acrylic acid of general formula II and the alcohol hydroxyl-modified silicone oil of general formula III are subjected to esterification reaction in the presence of a catalyst and a polymerization inhibitor, and then separated to obtain monosilane methacrylate.

[0016] (II)

[0017] (III)

[0018] In formula II, R is hydrogen or methyl; in formula III, R is alkyl, silyl or cycloalkyl; R2 is hydrogen or methyl; R2 is amino, benzene ring or hydrogen; n is 1-5; and m is 1-3.

[0019] The method for preparing monosilane methacrylate provided by this invention utilizes the properties of organosilicon oil as a linear polymer, which is hydrophobic and commonly used as a waterproofing agent in building materials, textiles, and paper. Small-molecule hydroxyl-terminated silicone oil and unsaturated carboxylic acids are selected as raw materials, and an esterification reaction is performed to generate a silane ester. This silane ester is then copolymerized with the unsaturated carboxylic acid to produce a PCE-like water-reducing agent with Si-O bonds as the core framework. This retains the easy film-forming properties of long-chain siloxanes (Si-O bond energy is 100 KJ / mol higher than C / C bond energy), high rigidity, and hydrophobic characteristics. The chelating effect of the unsaturated carboxylic acid groups with calcium ions enhances the waterproofing effect when used in gypsum-based mortar. The obtained monosilane methacrylate has certain hydrophobic properties, which allow the mortar to form a waterproof film upon contact with water, reducing water absorption and penetration, and effectively improving the waterproofing performance of gypsum-based mortar.

[0020] Meanwhile, the hydroxyl-terminated silane esters obtained have active hydroxyl groups and appropriate retarding effect. To a certain extent, they can delay the rapid hardening of anhydrous gypsum and maintain the workability of gypsum-based mortar.

[0021] Preferably, the catalyst is one or more selected from stannous sulfate, stannous chloride, stannous pyrophosphate, cuprous chloride, and phosphoric acid.

[0022] The catalyst is not only an esterification catalyst but also a hydroxyl protectant, preventing the oxidation of terminal hydroxyl groups. Furthermore, the catalyst can suppress the formation of diester products (byproducts), controlling the diester content within a certain range. During the reaction, the catalyst dissolves in an acidic solution. As the esterification reaction proceeds, free acid is consumed, and the pH concentration in the system gradually decreases. This reduces the dissolution effect of stannous salt in the catalyst, causing it to slowly precipitate and form microparticles. The rapid decrease in stannous ion concentration in the catalyst naturally slows down the esterification reaction. Even with increased system temperature and extended reaction time within a certain range, the diesterification rate does not increase, and the proportion of diester products (byproducts) remains around 3%-11%.

[0023] Preferably, the amount of catalyst added is 0.02%-0.2% of the total mass of (meth)acrylic acid and hydroxyl-modified silicone oil.

[0024] Preferably, the polymerization inhibitor is one or more of hydroquinone or phenothiazine, which prevents the self-polymerization of (meth)acrylic acid in the system at high temperature through free radical reaction, or prevents the unsaturated double bonds of the esterification product from being oxidized and losing their reactivity during storage.

[0025] Preferably, the amount of the polymerization inhibitor added is 0.02%-0.4% of the total mass of (meth)acrylic acid and hydroxyl-modified silicone oil.

[0026] Preferably, the molar ratio of (meth)acrylic acid and hydroxyl-modified silicone oil is 1.6-2.0%.

[0027] Preferably, the alcohol hydroxyl-modified silicone oil is a terminal hydroxyl amino-modified silicone oil, a double-terminated hydroxyl amino-modified silicone oil, or a terminal hydroxyl hydrogenated heterocyclic silicone oil.

[0028] Preferably, the alcohol hydroxyl-modified silicone oil is a double-terminated hydroxyl amino-modified silicone oil.

[0029] Preferably, the homopolymer molecular weight of the hydroxyl-modified silicone oil is between 100 and 3000.

[0030] Preferably, the homopolymer molecular weight of the hydroxyl-modified silicone oil is 200-600 or 800-1200.

[0031] Preferably, the esterification reaction is carried out under nitrogen protection, with stirring at 60-100°C for 40-120 min, followed by cooling to obtain a silane ester esterification solution.

[0032] Preferably, the silane esterification solution is separated by extraction to obtain the monosilane methacrylate of general formula I; specifically, the extraction process is as follows:

[0033] The silane esterification solution was dissolved in a saturated sodium chloride solution, stirred and dispersed completely, and allowed to stand for extraction. The upper oily liquid was disilane ester and silicone oil. The lower aqueous solution was collected, filtered through an RO (reverse osmosis) membrane, washed with purified water, and the component accumulated in the RO membrane tube was collected, which was monosilane methacrylate.

[0034] Preferably, the esterification reaction is carried out at a temperature of 75-85°C.

[0035] The present invention also provides a compound water-reducing agent, characterized in that:

[0036] The preparation is carried out by mixing component A and component B;

[0037] Component A comprises 80%-91% by weight of monosilane methacrylate, 3%-11% by weight of silane dimethacrylate, 0.3%-7% by weight of (meth)acrylic acid and 0.1%-10% by weight of hydroxyl-modified silicone oil.

[0038] Component B is either a polycarboxylate superplasticizer or a melamine superplasticizer.

[0039] The mass ratio of component A to component B is (3-9):(1-2).

[0040] The compound water-reducing agent provided by this invention combines the hydrophobic and oleophilic properties, longer chain length, and good film-forming effect of bissilane esters with the small molecular weight, easy film-forming, and high rigidity of monosilane esters. It has a good molecular film-forming effect and is excellent in terms of waterproofing and compressive strength when applied to gypsum-based mortars.

[0041] Furthermore, the silane esterification liquid produced during the preparation process of this invention contains disilane esters and monosilane esters in the required ratio without the need for separation and proportioning. It can directly achieve a weight ratio of 80%-91% monosilane methacrylate, 3%-11% disilane methacrylate, 0.3%-7% (meth)acrylic acid, and 0.1%-10% alcohol hydroxyl-modified silicone oil. The above silicone oil ester mixture is directly copolymerized with acrylic acid to obtain a silane ester water-reducing agent.

[0042] Preferably, when the homopolymer molecular weight of the alcohol hydroxyl modified silicone oil is between 800 and 1200, the ratio of monosilane methacrylate to disilane methacrylate is 100:7-13, resulting in the best molecular film-forming effect and the best waterproofing effect when applied to gypsum-based self-leveling mortar.

[0043] Preferably, when the homopolymer molecular weight of the alcohol hydroxyl modified silicone oil is between 200 and 600, the ratio of monosilane methacrylate to disilane methacrylate is 100:3-9, which has the defoaming effect of silane esters and the microsphere effect of Si-O, and has a good viscosity reduction effect on high-grade concrete.

[0044] This invention also provides a method for preparing a compound water-reducing agent, characterized in that:

[0045] The preparation method of component A is as follows:

[0046] Component A is obtained by esterification of (meth)acrylic acid of general formula II and hydroxyl-modified silicone oil of general formula III under the action of a catalyst and a polymerization inhibitor.

[0047] (II)

[0048] (III)

[0049] In general formula II, R is hydrogen or methyl, in general formula III, R is alkyl, silyl or cycloalkyl, R2 is amino, benzene ring or hydrogen, n is 1-5, and m is 1-3.

[0050] Component B is either a polycarboxylate superplasticizer or a melamine superplasticizer;

[0051] The prepared component A and component B are mixed evenly at a mass ratio of (3-9):(1-2) to obtain the compound water-reducing agent.

[0052] Preferably, the polycarboxylate superplasticizer is an ether-based or ester-based polycarboxylate superplasticizer.

[0053] Aqueous solution.

[0054] The compound water-reducing agent provided by this invention is more suitable for gypsum-based self-leveling mortar compared with existing technologies, and its waterproof (anti-water) effect, anti-seepage pressure and compressive strength are all excellent. Detailed Implementation

[0055] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0056] The present invention provides the following embodiments:

[0057] Example 1:

[0058] In a flask, add 306g of homopolymer 200-molecular-weight bihydroxyl-terminated amino silicone oil and 247.63g of methacrylic acid. Start heating and stirring, then add 0.42g of hydroquinone, 1.47g of stannous sulfate and 0.24g of phenothiazine. Purge with nitrogen gas and stir at 76-85℃ for 40-90min. Cool to room temperature to obtain an aminosilane methacrylate esterified solution.

[0059] In the aminosilane methacrylate esterification solution, monosilane methacrylate accounts for 90.63%, dimethacrylate silane accounts for 3.74%, free methacrylic acid accounts for 0.37%, free hydroxyl-terminated amino silicone oil accounts for 2.68%, and the remainder consists of a small amount of methyl silicone oil entrained in the raw material hydroxyl-terminated silicone oil, residual methacrylic acid self-polymers and water in the esterification product.

[0060] The aminosilane methacrylate esterification liquid and the ether-based polycarboxylic acid water-reducing agent are mixed at a mass ratio of 9:1 to prepare water-reducing agent #1.

[0061] The formulations of ether-based polycarboxylate superplasticizers are shown in Table 1 below:

[0062] Table 1. Formulation ratio of ether-based polycarboxylate superplasticizers

[0063]

[0064] Example 2:

[0065] Add 338g of homopolymer 600 dihydroxyl hydrogenated benzene ring modified silicone oil and 80.48g of acrylic acid to a flask, start stirring, add 0.38g of hydroquinone, 1.24g of stannous chloride and 0.27g of phenothiazine, purge with nitrogen, heat to 68-75℃, and maintain the temperature with stirring for 60-120 minutes. Cool down to obtain the hydroxyl-terminated hydrogenated benzene ring silicone oil acrylated solution.

[0066] In the acrylate esterification solution of hydroxyl-terminated hydrogenated benzene ring silicone oil, the proportion of monosilane acrylate is 89.39%, the proportion of hydrogenated silicone oil diester is 4.91%, the proportion of free acrylic acid is 1.08%, the proportion of free dihydroxyl-terminated hydrogenated benzene ring modified silicone oil is 1.98%, and the remainder is a small amount of methyl silicone oil entrained in the raw material dihydroxyl-terminated hydrogenated benzene ring silicone oil, the residual acrylic acid self-polymer and water in the esterification product.

[0067] The hydroxyl-terminated hydrogenated silicone oil acrylated liquid and melamine-type water-reducing agent were mixed at a mass ratio of 3:2 to prepare water-reducing agent #2.

[0068] The formulation ratios of melamine-type water-reducing agents are shown in Table 1 below:

[0069] Table 1. Formulation ratio of melamine-based water-reducing agents

[0070]

[0071] Example 3:

[0072] Add 298g of homopolymer 800 dihydroxyamino silicone oil and 61.02g of methacrylic acid to a flask, start stirring, add 0.42g of hydroquinone, 0.87g of cuprous chloride and 0.48g of stannous chloride, purge with nitrogen, heat to 82-88℃, and maintain the temperature with stirring for 60-80 minutes. Cool to obtain the hydroxyl-terminated amino silicone oil methacrylate esterified solution.

[0073] In the methacrylic acid esterification solution of hydroxyl-terminated silicone oil, monosilane methacrylate accounts for 81.63%, bissilane dimethacrylate accounts for 6.74%, free methacrylic acid accounts for 0.89%, free dihydroxyl silicone oil accounts for 9.37%, and the remainder consists of a small amount of methyl silicone oil entrained in the raw material hydroxyl-terminated silicone oil, residual methacrylic acid self-polymers and water in the esterification product.

[0074] The hydroxyl-terminated silicone oil methacrylate esterification liquid and the ester-based polycarboxylic acid water-reducing agent were mixed at a mass ratio of 7:1 to prepare water-reducing agent #3.

[0075] Example 4:

[0076] Add 360g of homopolymer 1200 dihydroxyphenyl modified silicone oil and 40.54g of acrylic acid to a flask, start stirring, add 0.40g of hydroquinone, 1.28g of stannous pyrophosphate, 0.23g of phosphoric acid and 0.24g of phenothiazine, purge with nitrogen, heat to 85-98℃, and maintain the temperature while stirring for 40-70 minutes. Cool down to obtain the hydroxyphenyl-terminated silicone oil acrylate solution.

[0077] In the acrylate esterification solution of hydroxyl-terminated phenyl-modified silicone oil, hydroxyl-terminated phenyl-modified silicone oil acrylate monoester accounts for 80.38%, diacrylate silane ester accounts for 10.84%, free acrylic acid accounts for 6.37%, free dihydroxyl-terminated phenyl-modified silicone oil accounts for 0.13%, and the remainder consists of a small amount of methyl silicone oil entrained in the raw material hydroxyl-terminated phenyl-modified silicone oil, residual acrylic acid self-polymers and water in the esterification product.

[0078] The hydroxyl-terminated phenyl silicone oil acrylated liquid was copolymerized with acrylic acid, and after neutralization with liquid alkali, it became water-reducing agent #4.

[0079] Comparative Example 1:

[0080] It is an ether-based polycarboxylate superplasticizer, and the specific formulation is shown in Table 1 above.

[0081] Comparative Example 2:

[0082] It is a melamine-based water-reducing agent, and the specific formulation is shown in Table 2 above.

[0083] Comparative Example 3:

[0084] It is an ester-based polycarboxylate superplasticizer, and the specific formulation is shown in Table 3 below.

[0085] Table 3. Formulation ratio of ester-based polycarboxylate superplasticizers

[0086]

[0087] Comparative Example 4:

[0088] Comparative Example 4 replaced the aminosilane methacrylate esterification solution in Example 1 with 3-(trimethoxysilyl)propyl methacrylate esterification solution, and all other aspects were the same as in Example 1.

[0089] Add 306 g of 3-(trimethoxysilyl)propanol and 247.63 g of methacrylic acid to a flask, start heating and stirring, then add 0.42 g of hydroquinone, 1.47 g of stannous sulfate and 0.24 g of phenothiazine, purge with nitrogen gas, and stir at 76-85 °C for 40-90 min. Cool to room temperature to obtain the esterified solution of 3-(trimethoxysilyl)propyl methacrylate.

[0090] In the esterification solution of 3-(trimethoxysilyl)propyl methacrylate, the proportion of 3-(trimethoxysilyl)propyl methacrylate is 88.96%, the proportion of free methacrylic acid is 6.91%, the proportion of free 3-(trimethoxysilyl)propanol is 2.47%, and the remainder is impurities in the raw materials and a small amount of water.

[0091] To demonstrate the superior technical effects of the water-reducing agent provided by this invention compared to existing water-reducing agents, this invention will combine the above embodiments and comparative examples, and test the performance of gypsum-based self-leveling mortar according to standards JC / T 1023-2021 gypsum-based self-leveling mortar, JG / T 230-2007 premixed mortar, and JGJ / T 70-2009 basic performance test methods for building mortar. Two types of commercially available gypsum-based mortar substrates (α-hemihydrate gypsum and β-hemihydrate gypsum) will be used to compare the water-reducing agents prepared in Examples 1-4 and Comparative Examples 1-4. The performance will be evaluated based on indicators such as initial flowability, 30-minute flowability, water absorption rate, impermeability pressure, and compressive strength.

[0092] In Examples 1-4 and Comparative Examples 1-4, the initial fluidity water ratio was 22.4%, and the amount of water-reducing agent added was 1.6-2.0% of the substrate content in the gypsum-based mortar to ensure the initial fluidity of the self-leveling mortar and maintain its workability for approximately 40 minutes.

[0093] The test results are shown in Table 4 below:

[0094] Table 4. Performance test results of the gypsum-based self-leveling mortars described in Examples 1-4 and Comparative Examples 1-4

[0095]

[0096] Compared with the water-reducing agents of Comparative Examples 1-4, the water-reducing agent prepared in the embodiments of the present invention can effectively improve the water resistance, seepage pressure resistance and compressive strength of gypsum-based self-leveling mortar. This indicates that the silane ester prepared in the present invention has a good waterproof effect when applied to gypsum-based self-leveling mortar and can effectively improve the strength of gypsum-based self-leveling mortar.

[0097] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A monosilane methacrylate, as described in general formula I, characterized in that: （I） Wherein, R is an alkylene group, R1 is hydrogen or methyl, R2 is amino or phenyl, n is 1-5, and m is 1-3.

2. A method for preparing monosilane methacrylate as described in claim 1, characterized in that: The (meth)acrylic acid of general formula II and the alcohol hydroxyl-modified silicone oil of general formula III are subjected to esterification reaction in the presence of a catalyst and a polymerization inhibitor, and then separated to obtain monosilane methacrylate. (II) (III) In general formula II, R1 is hydrogen or methyl, R in general formula III is alkylene, R2 is amino or phenyl, n is 1-5, and m is 1-3; The catalyst is one or more of stannous sulfate, stannous chloride, stannous pyrophosphate, and cuprous chloride.

3. The preparation method according to claim 2, characterized in that: The catalyst is added at a rate of 0.02%-0.2% of the total mass of (meth)acrylic acid and hydroxyl-modified silicone oil.

4. The preparation method according to claim 2, characterized in that: The polymerization inhibitor is one or more of hydroquinone or phenothiazine, and the amount of the polymerization inhibitor added is 0.02%-0.4% of the total mass of (meth)acrylic acid and alcohol hydroxyl modified silicone oil.

5. The preparation method according to claim 2, characterized in that: The molar ratio of (meth)acrylic acid and hydroxyl-modified silicone oil is 1.6-2.

0.

6. The preparation method according to claim 2, characterized in that: The homopolymer molecular weight of the hydroxyl-modified silicone oil is between 100 and 3000.

7. The preparation method according to claim 2, characterized in that: The esterification reaction was carried out under nitrogen protection and stirred for 40-120 minutes at a temperature of 60-100℃.

8. A compound water-reducing agent, characterized in that: The preparation is carried out by mixing component A and component B; Component A comprises 80%-91% by weight of the monosilane methacrylate as described in claim 1, 3%-11% of the dimethacrylate silane ester, 0.3%-7% of (meth)acrylic acid and 0.1%-10% of the alcohol hydroxyl-modified silicone oil. Component B is either a polycarboxylate superplasticizer or a melamine superplasticizer. The mass ratio of component A to component B is (3-9):(1-2).

9. A method for preparing a compound water-reducing agent according to claim 8, characterized in that: The preparation method of component A is as follows: Component A is obtained by esterification of (meth)acrylic acid of general formula II and hydroxyl-modified silicone oil of general formula III under the action of a catalyst and a polymerization inhibitor. (II) (III) In general formula II, R1 is hydrogen or methyl, R in general formula III is alkylene, R2 is amino or phenyl, n is 1-5, and m is 1-3; Component B is either a polycarboxylate superplasticizer or a melamine superplasticizer; The prepared component A and component B are mixed evenly at a mass ratio of (3-9):(1-2) to obtain the compound water-reducing agent.

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