Self-thickening vinyl acetate-acrylic emulsion and preparation method thereof

Abstract

The invention relates to the technical field of vinyl acetate-acrylic emulsion preparation methods, in particular to a self-thickening vinyl acetate-acrylic emulsion and a preparation method thereof.According to the self-thickening vinyl acetate-acrylic emulsion prepared through the method, an anionic emulsifier and a nonionic emulsifier are used in cooperation, the stability of the emulsion is improved, and the stability of the emulsion is improved; the used nonionic emulsifier can further increase the thickness of a hydrated layer, so that the defect of poor stability of the vinyl acetate-acrylic emulsion is overcome; secondly, the acrylic hydrophilic monomer is added, so that the prepared vinyl acetate-acrylic emulsion has a self-thickening effect, and the production cost is reduced on the basis of improving the stability and powder holding capacity of the emulsion; and finally, the added crosslinking monomer can be subjected to crosslinking reaction with vinyl acetate and alkyl acrylate monomers to form a crosslinking film, so that the crosslinking density of the vinyl acetate-acrylic emulsion and the bond energy of molecular chain group connection are greatly improved, and the adhesive force, the tensile strength and the elongation at break are improved.

Description

Technical Field

[0001] The invention relates to the technical field of methods for preparing acetic acid acrylic emulsion, and in particular to a self-thickening acetic acid acrylic emulsion and a preparation method thereof. Background Art

[0002] Building sealants are used to seal various joints or holes in buildings to prevent gas, liquid, and solid from penetrating and to prevent structural materials from being damaged when the structure is displaced, thereby playing the role of heat preservation, sound insulation, waterproofing, dustproofing, gas proofing, fireproofing, corrosion resistance, shock absorption, and preventing the accumulation of foreign matter in joints. Acetyl acetate building sealant is widely used in high-rise buildings, large frame hanging board structures, glass curtain walls, insulating glass and other new building materials with its good performance and low price. The effect of the emulsion used on the performance of the sealant is very obvious.

[0003] The raw materials of vinyl acetate-acrylic sealant mainly include vinyl acetate-acrylic emulsion, heavy calcium powder, plasticizer, cellulose, dispersant, etc. Among them, vinyl acetate-acrylic emulsion is the most important component that determines the performance of vinyl acetate-acrylic sealant. Early sealant emulsions were mainly based on vinyl acetate-ethylene copolymer emulsions, but this emulsion has a small powder holding capacity, which makes the sealant cost high and does not meet market requirements. Therefore, how to prepare a vinyl acetate-acrylic sealant emulsion with a large powder holding capacity, low film-forming temperature and low cost has become a technical problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0004] Technical issues solved In view of the above-mentioned shortcomings of the prior art, the present invention provides a self-thickening vinyl acetate acrylic emulsion and a preparation method thereof, aiming to prepare a vinyl acetate acrylic sealant emulsion with large powder holding capacity, low film-forming temperature and low cost.

[0005] Technical Solution To achieve the above objectives, the present invention is implemented through the following technical solutions: A self-thickening acetoacetic acid acrylate emulsion, the self-thickening acetoacetic acid acrylate emulsion is composed of the following components: modified mesoporous titanium dioxide, modified starch, vinyl acetate, alkyl acrylate monomers, acrylic acid hydrophilic monomers, cross-linking monomers, emulsifier components, buffer components, initiator components and deionized water; The modified mesoporous titanium dioxide is prepared by modifying the mesoporous titanium dioxide with polyethyleneimine; The modified starch is prepared by oxidatively modifying cassava starch.

[0006] Furthermore, the preparation steps of the mesoporous titanium dioxide are: Step 1, weigh 4-5g of hexadecyltrimethylammonium bromide and 48mL of deionized water into a flask, add 36g of tetrabutyl titanate and stir at 300r / min for 2h, then add 10g of deionized water and 36g of anhydrous ethanol and stir at 200r / min for 3h under condensation reflux conditions at 88°C, cool to room temperature, filter and wash with deionized water three times, and then dry in an oven at 80°C to constant weight, the obtained product is recorded as crude titanium dioxide; Step 2: Pour 3 mL of 36% hydrochloric acid solution into 30 mL of 80% ethanol aqueous solution, add 5-8 g of crude titanium dioxide under stirring at a speed of 200 r / min, continue stirring for 48 hours, filter and wash with deionized water three times, place in an oven at 60°C and dry for 4 hours to obtain mesoporous titanium dioxide.

[0007] Furthermore, the preparation method of the modified mesoporous titanium dioxide is: weigh 2-3g of mesoporous titanium dioxide and disperse it in 100mL of anhydrous ethanol, ultrasonically disperse it at a frequency of 28kHz for 30min, then add 1-2g of polyethyleneimine, then heat to 58°C and stir at a speed of 200r / min for 8h, and finally centrifuge at a speed of 6000r / min for 20min, and the resulting precipitate is the modified mesoporous titanium dioxide.

[0008] Furthermore, the preparation method of the modified starch is: weigh 12-15g of cassava starch and dissolve it in 50g of deionized water, add a 20% sodium hydroxide aqueous solution by mass to adjust the pH value to 10, then add 3-5g of hydrogen peroxide, stir at a speed of 300r / min for 10min, then heat to 50-60°C and keep warm for 40-60min, and the obtained is the modified starch.

[0009] Furthermore, the alkyl acrylate monomer is at least one of isooctyl acrylate, ethyl acrylate, butyl acrylate, methyl acrylate, lauryl acrylate, n-propyl acrylate and 2-ethylhexyl methacrylate; the olefinic hydrophilic monomer is at least one of acrylic acid, hydroxyethyl acrylate, methacrylic acid, itaconic acid and hydroxypropyl acrylate; the crosslinking monomer is at least one of vinyl trimethoxy silane, glycidyl acrylate, γ-methacryloxypropyl trimethoxy silane, dimethylaminoethyl methacrylate and trimethylolpropane triacrylate.

[0010] Furthermore, the emulsifier component is prepared by mixing an anionic emulsifier and a nonionic emulsifier in a weight ratio of 1-10:1-10, the anionic emulsifier is at least one of sodium dodecylbenzene sulfonate, sodium dodecyl diphenyl ether disulfonic acid, sodium dodecyl sulfate, sodium acrylamide-2-methylpropane sulfonate, sodium vinyl sulfonate and dialkyl-2-sulfosuccinate sodium, and the nonionic emulsifier is at least one of lauryl oleyl alcohol polyoxyethylene ether, stearyl alcohol polyoxyethylene ether, polyoxyethylene sorbitan monooleate and fatty alcohol polyoxyethylene ether.

[0011] Furthermore, the buffer component is at least one of sodium bicarbonate, ammonium bicarbonate, disodium hydrogen phosphate, sodium carbonate, ammonium carbonate and sodium acetate, and the initiator component is at least one of ammonium persulfate, sodium persulfate and potassium persulfate.

[0012] A method for preparing a self-thickening acetoacetic acid acrylate emulsion, the preparation method comprising: S1. Weigh 6-8 parts of modified mesoporous titanium dioxide, 8-12 parts of modified starch, 70-100 parts of vinyl acetate, 20-50 parts of alkyl acrylate monomers, 1-5 parts of acrylic acid hydrophilic monomers, 0.5-2 parts of cross-linking monomers, 3-4 parts of emulsifier components, 0.5-1 parts of buffer components and 100-130 parts of deionized water by weight, mix them, and mix and disperse them uniformly to obtain a pre-emulsion; S2, 0.5-2 parts by weight of the initiator component and 10 parts by weight of deionized water are mixed, and the mixture obtained after mixed dissolution is recorded as the initiator solution; S3, weighing 1-4 parts of emulsifier component and 0.5-1 parts of buffer component by weight, pouring into the reaction kettle, heating to 60-80°C, adding dropwise 0.5%-5% of the total amount of pre-emulsion and 30% of the total amount of initiator solution, and reacting for 10-30 minutes, the result is recorded as the reaction system; S4. Raise the temperature of the reaction system in the reactor to 60-80°C, then drop the remaining pre-emulsion and the remaining initiator solution, and keep the reaction warm for 1-2 hours after the addition is completed. Then cool to 50°C and filter with a 200-mesh sieve to obtain a self-thickening acetic acid propylene emulsion.

[0013] Furthermore, in S1, the specific operation of mixing and dispersing uniformly is stirring at a speed of 500 r / min for 10 min, and in S2, the specific operation of mixing and dissolving is stirring at a speed of 500 r / min for 5 min.

[0014] Furthermore, the dripping rate in S3 and S4 is 1 drop / s.

[0015] Beneficial Effects The present invention provides a self-thickening acetic acid acrylate emulsion and a preparation method thereof. Compared with the prior art, the present invention has the following beneficial effects: 1. The self-thickening acetoacetic acid acrylate emulsion prepared by the present invention adopts anionic emulsifier and nonionic emulsifier in combination, thereby increasing the stability of the emulsion. The nonionic emulsifier used can further increase the thickness of the hydration layer, thereby solving the disadvantage of poor stability of the acetoacetic acid acrylate emulsion. Secondly, the acrylic acid hydrophilic monomer added in the present invention can make the prepared acetoacetic acid acrylate emulsion have the effect of increasing self-thickening, thereby reducing the production cost on the basis of improving the emulsion stability and powder holding capacity. Finally, the cross-linking monomer added in the present invention can react with vinyl acetate and alkyl acrylate monomers to form a cross-linked film, thereby greatly increasing the cross-linking density of the acetoacetic acid acrylate emulsion and the bond energy of the molecular chain group connection, thereby increasing the adhesion, tensile strength and elongation at break. The preparation method of the self-thickening acetoacetic acid acrylate emulsion in the present invention is simple in process and low in cost, and has excellent market promotion value.

[0016] 2. The present invention adds mesoporous titanium dioxide modified with polyethyleneimine to the preparation of a self-thickening vinyl acetate acrylic emulsion. Since the mesoporous titanium dioxide itself has a relatively high hardness, after being modified with polyethyleneimine, its hardness contribution in the vinyl acetate acrylic emulsion can be further improved, thereby enhancing the wear resistance of the vinyl acetate acrylic emulsion adhesive layer. Secondly, the addition of modified mesoporous titanium dioxide can indirectly promote the self-thickening effect of the coating by affecting the rheological properties of the vinyl acetate acrylic emulsion, making the coating easier to control during construction and reducing the occurrence of sagging. Moreover, the nano-scale modified mesoporous titanium dioxide helps to form a uniform dispersion system in the emulsion, thereby improving the coating uniformity and making the adhesive layer surface smoother. Furthermore, the addition of modified mesoporous titanium dioxide can slow down the diffusion rate of the corrosive medium in the adhesive layer by changing the microstructure of the adhesive layer, thereby further improving the anti-corrosion effect of the adhesive layer.

[0017] 3. The modified starch oxidized with hydrogen peroxide added to the present invention can improve the film-forming property of the emulsion, so that the adhesive layer can form a tougher and denser film layer after drying, and improve the weather resistance and durability of the adhesive layer. The functional groups such as hydroxyl groups in the oxidized starch can chemically react or physically adsorb with the surface of the substrate, thereby enhancing the adhesion between the emulsion adhesive layer and the substrate and reducing the risk of peeling of the adhesive layer. Secondly, the starch treated with hydrogen peroxide can have better water resistance, so after adding the emulsion, the water resistance of the adhesive layer can be improved, and the failure of the adhesive layer caused by water penetration can be prevented. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] The present invention will be further described below in conjunction with the embodiments.

[0020] Example 1 A self-thickening acetoacetic acid acrylate emulsion of the present embodiment, the self-thickening acetoacetic acid acrylate emulsion is composed of the following components: modified mesoporous titanium dioxide, modified starch, vinyl acetate, alkyl acrylate monomers, acrylic acid hydrophilic monomers, cross-linking monomers, emulsifier components, buffer components, initiator components and deionized water; The modified mesoporous titanium dioxide is prepared by modifying the mesoporous titanium dioxide with polyethyleneimine, wherein the preparation steps of the mesoporous titanium dioxide are as follows: Step 1, weigh 4g of hexadecyltrimethylammonium bromide and 48mL of deionized water into a flask, add 36g of tetrabutyl titanate and stir at 300r / min for 2h, then add 10g of deionized water and 36g of anhydrous ethanol and stir at 200r / min for 3h under condensation reflux conditions at 88°C, cool to room temperature, filter and wash with deionized water three times, and then dry in an oven at 80°C to constant weight, the obtained product is recorded as crude titanium dioxide; Step 2: Pour 3 mL of 36% hydrochloric acid solution into 30 mL of 80% ethanol aqueous solution, add 5 g of crude titanium dioxide under stirring at a speed of 200 r / min, continue stirring for 48 hours, filter and wash with deionized water three times, place in an oven at 60°C and dry for 4 hours to obtain mesoporous titanium dioxide.

[0021] The preparation method of modified mesoporous titanium dioxide is as follows: weigh 2g of mesoporous titanium dioxide and disperse it in 100mL of anhydrous ethanol, add 1g of polyethyleneimine after ultrasonic dispersion at a frequency of 28kHz for 30min, then heat to 58°C and stir at a speed of 200r / min for 8h, and finally centrifuge at a speed of 6000r / min for 20min. The resulting precipitate is the modified mesoporous titanium dioxide.

[0022] The modified starch is prepared by oxidatively modifying cassava starch, wherein the preparation method of the modified starch is as follows: 12 g of cassava starch is weighed and dissolved in 50 g of deionized water, a 20% sodium hydroxide aqueous solution is added dropwise to adjust the pH value to 10, and then 3 g of hydrogen peroxide is added, and the mixture is stirred at a speed of 300 r / min for 10 min, and then the temperature is raised to 50° C. and kept warm for 40 min, and the result is the modified starch.

[0023] The alkyl acrylate monomer is butyl acrylate; the olefinic acid hydrophilic monomer is acrylic acid; and the crosslinking monomer is gamma-methacryloxypropyltrimethoxysilane.

[0024] The emulsifier component is prepared by mixing an anionic emulsifier and a nonionic emulsifier in a weight ratio of 1:10, the anionic emulsifier is sodium dodecylbenzene sulfonate, and the nonionic emulsifier is fatty alcohol polyoxyethylene ether.

[0025] The buffer component is sodium bicarbonate, and the initiator component is ammonium persulfate.

[0026] A method for preparing a self-thickening acetic acid acrylic emulsion, the preparation method comprising: S1. Weigh 6 parts of modified mesoporous titanium dioxide, 8 parts of modified starch, 70 parts of vinyl acetate, 20 parts of alkyl acrylate monomers, 1 part of acrylic acid hydrophilic monomers, 0.5 parts of cross-linking monomers, 3 parts of emulsifier components, 0.5 parts of buffer components and 100 parts of deionized water by weight, and mix them. The specific operation of mixing and dispersing uniformly is to stir at a speed of 500 r / min for 10 minutes, and the result is recorded as a pre-emulsion; S2, 0.5 parts by weight of the initiator component and 10 parts by weight of deionized water were mixed, and the mixture was stirred at a speed of 500 r / min for 5 minutes to obtain an initiator solution; S3, weighing 1 part of the emulsifier component and 0.5 parts of the buffer component by weight, pouring them into the reaction kettle, heating to 60°C, adding 0.5% of the pre-emulsion solution by weight and 30% of the initiator solution by weight at a drop rate of 1 drop / s, and reacting for 10 minutes, and the result is recorded as the reaction system; S4. Raise the temperature of the reaction system in the reactor to 60°C, then drop the remaining pre-emulsion and the remaining initiator solution at a rate of 1 drop / s. After the addition is completed, keep the temperature for reaction for 1 hour, cool to 50°C, and filter with a 200-mesh sieve to obtain a self-thickening acetic acid propylene emulsion.

[0027] Example 2 A self-thickening acetoacetic acid acrylate emulsion of the present embodiment, the self-thickening acetoacetic acid acrylate emulsion is composed of the following components: modified mesoporous titanium dioxide, modified starch, vinyl acetate, alkyl acrylate monomers, acrylic acid hydrophilic monomers, cross-linking monomers, emulsifier components, buffer components, initiator components and deionized water; The modified mesoporous titanium dioxide is prepared by modifying the mesoporous titanium dioxide with polyethyleneimine, wherein the preparation steps of the mesoporous titanium dioxide are as follows: Step 1, weigh 5g of hexadecyltrimethylammonium bromide and 48mL of deionized water into a flask, add 36g of tetrabutyl titanate and stir at 300r / min for 2h, then add 10g of deionized water and 36g of anhydrous ethanol and stir at 200r / min for 3h under condensation reflux conditions at 88°C, cool to room temperature, filter and wash with deionized water three times, and then dry in an oven at 80°C to constant weight, the obtained product is recorded as crude titanium dioxide; Step 2: Pour 3 mL of 36% hydrochloric acid solution into 30 mL of 80% ethanol aqueous solution, add 8 g of crude titanium dioxide under stirring at a speed of 200 r / min, continue stirring for 48 hours, filter and wash with deionized water three times, place in an oven at 60°C and dry for 4 hours to obtain mesoporous titanium dioxide.

[0028] The preparation method of modified mesoporous titanium dioxide is as follows: 3 g of mesoporous titanium dioxide is weighed and dispersed in 100 mL of anhydrous ethanol, and then 2 g of polyethyleneimine is added after ultrasonic dispersion at a frequency of 28 kHz for 30 minutes, followed by heating to 58°C and stirring at a speed of 200 r / min for 8 hours, and finally centrifuging at a speed of 6000 r / min for 20 minutes. The resulting precipitate is the modified mesoporous titanium dioxide.

[0029] The modified starch is prepared by oxidatively modifying cassava starch, wherein the preparation method of the modified starch is as follows: 15 g of cassava starch is weighed and dissolved in 50 g of deionized water, a 20% sodium hydroxide aqueous solution is added dropwise to adjust the pH value to 10, and then 5 g of hydrogen peroxide is added, and the mixture is stirred at a speed of 300 r / min for 10 min, and then the temperature is raised to 60° C. and kept warm for 60 min, and the result is the modified starch.

[0030] The alkyl acrylate monomer is butyl acrylate; the olefinic acid hydrophilic monomer is acrylic acid and methacrylic acid mixed in equal weight ratio; and the crosslinking monomer is gamma-methacryloxypropyltrimethoxysilane.

[0031] The emulsifier component is prepared by mixing an anionic emulsifier and a nonionic emulsifier in a weight ratio of 10:1. The anionic emulsifier is sodium dodecylbenzene sulfonate, and the nonionic emulsifier is fatty alcohol polyoxyethylene ether.

[0032] The buffer component is sodium bicarbonate, and the initiator component is ammonium persulfate.

[0033] A method for preparing a self-thickening acetic acid acrylic emulsion, the preparation method comprising: S1. Weigh 8 parts of modified mesoporous titanium dioxide, 12 parts of modified starch, 100 parts of vinyl acetate, 50 parts of alkyl acrylate monomers, 5 parts of acrylic acid hydrophilic monomers, 2 parts of cross-linking monomers, 4 parts of emulsifier components, 1 part of buffer component and 130 parts of deionized water by weight, and mix them. The specific operation of mixing and dispersing them uniformly is to stir at a speed of 500 r / min for 10 minutes, and the result is recorded as a pre-emulsion; S2, 2 parts by weight of the initiator component and 10 parts by weight of deionized water were mixed, and the mixture was stirred at a speed of 500 r / min for 5 min to obtain an initiator solution; S3, weigh 4 parts of emulsifier component and 1 part of buffer component by weight, pour them into the reaction kettle, heat to 80°C, add 5% of the pre-emulsion by weight and 30% of the initiator solution by weight at a drop rate of 1 drop / s, and react for 30 minutes. The result is recorded as the reaction system; S4. Raise the temperature of the reaction system in the reactor to 80°C, then drop the remaining pre-emulsion and the remaining initiator solution at a rate of 1 drop / s. After the addition is completed, keep the temperature for 2 hours, cool to 50°C, and filter with a 200-mesh sieve to obtain a self-thickening acetic acid propylene emulsion.

[0034] Example 3 A self-thickening acetoacetic acid acrylate emulsion of the present embodiment, the self-thickening acetoacetic acid acrylate emulsion is composed of the following components: modified mesoporous titanium dioxide, modified starch, vinyl acetate, alkyl acrylate monomers, acrylic acid hydrophilic monomers, cross-linking monomers, emulsifier components, buffer components, initiator components and deionized water; The modified mesoporous titanium dioxide is prepared by modifying the mesoporous titanium dioxide with polyethyleneimine, wherein the preparation steps of the mesoporous titanium dioxide are as follows: Step 1, weigh 5g of hexadecyltrimethylammonium bromide and 48mL of deionized water into a flask, add 36g of tetrabutyl titanate and stir at 300r / min for 2h, then add 10g of deionized water and 36g of anhydrous ethanol and stir at 200r / min for 3h under condensation reflux conditions at 88°C, cool to room temperature, filter and wash with deionized water three times, and then dry in an oven at 80°C to constant weight, the obtained product is recorded as crude titanium dioxide; Step 2: Pour 3 mL of 36% hydrochloric acid solution into 30 mL of 80% ethanol aqueous solution, add 6 g of crude titanium dioxide under stirring at a speed of 200 r / min, continue stirring for 48 hours, filter and wash with deionized water three times, place in an oven at 60°C and dry for 4 hours to obtain mesoporous titanium dioxide.

[0035] The preparation method of modified mesoporous titanium dioxide is as follows: 3 g of mesoporous titanium dioxide is weighed and dispersed in 100 mL of anhydrous ethanol, and then 2 g of polyethyleneimine is added after ultrasonic dispersion at a frequency of 28 kHz for 30 minutes, followed by heating to 58°C and stirring at a speed of 200 r / min for 8 hours, and finally centrifuging at a speed of 6000 r / min for 20 minutes. The resulting precipitate is the modified mesoporous titanium dioxide.

[0036] The modified starch is prepared by oxidatively modifying cassava starch, wherein the preparation method of the modified starch is as follows: 14 g of cassava starch is weighed and dissolved in 50 g of deionized water, a 20% sodium hydroxide aqueous solution is added dropwise to adjust the pH value to 10, and then 4 g of hydrogen peroxide is added, and the mixture is stirred at a speed of 300 r / min for 10 min, and then the temperature is raised to 55° C. and kept warm for 50 min, and the result is the modified starch.

[0037] The alkyl acrylate monomer is a mixture of isooctyl acrylate and butyl acrylate in an equal weight ratio; the olefinic acid hydrophilic monomer is acrylic acid; and the crosslinking monomer is gamma-methacryloxypropyltrimethoxysilane.

[0038] The emulsifier component is prepared by mixing anionic emulsifier and nonionic emulsifier in a weight ratio of 3:4, the anionic emulsifier is sodium dodecylbenzene sulfonate, and the nonionic emulsifier is fatty alcohol polyoxyethylene ether.

[0039] The buffer component is sodium bicarbonate, and the initiator component is ammonium persulfate.

[0040] A method for preparing a self-thickening acetic acid acrylic emulsion, the preparation method comprising: S1. Weigh 7 parts of modified mesoporous titanium dioxide, 10 parts of modified starch, 80 parts of vinyl acetate, 40 parts of alkyl acrylate monomers, 3 parts of acrylic acid hydrophilic monomers, 1 part of cross-linking monomers, 4 parts of emulsifier components, 1 part of buffer component and 120 parts of deionized water by weight, and mix them. The specific operation of mixing and dispersing them uniformly is to stir at a speed of 500 r / min for 10 minutes, and the result is recorded as a pre-emulsion; S2, 1 part by weight of the initiator component and 10 parts by weight of deionized water were mixed, and the mixture was stirred at a speed of 500 r / min for 5 min to obtain an initiator solution; S3, weigh 3 parts of emulsifier component and 1 part of buffer component by weight, pour them into the reaction kettle, heat to 70°C, add 3% of the pre-emulsion by weight and 30% of the initiator solution by weight at a drop rate of 1 drop / s, and react for 20 minutes. The result is recorded as the reaction system; S4. Raise the temperature of the reaction system in the reactor to 70°C, then drop the remaining pre-emulsion and the remaining initiator solution at a rate of 1 drop / s. After the addition is completed, keep the temperature for 2 hours, cool to 50°C, and filter with a 200-mesh sieve to obtain a self-thickening acetic acid propylene emulsion.

[0041] Comparative Example 1 The self-thickening acetic acid acrylate emulsion and the preparation method thereof provided in this comparative example are substantially the same as those in Example 1, with the main difference being that in this comparative example 1, the modified mesoporous titanium dioxide in Example 1 is replaced by nano-silicon dioxide.

[0042] Comparative Example 2 The self-thickening acetic acid acrylic emulsion and the preparation method thereof provided in this comparative example are substantially the same as those in Example 1, with the main difference being that in this comparative example 2, the modified starch in Example 1 is replaced with cassava starch.

[0043] Comparative Example 3 The self-thickening acetic acid acrylate emulsion and the preparation method thereof provided in this comparative example are substantially the same as those in Example 1, with the main difference being that in this comparative example 3, the cross-linking monomer in Example 1 is replaced with deionized water.

[0044] Performance Testing The self-thickening acetoacrylate emulsions in Examples 1-3 and Comparative Examples 1-3 are marked as Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2 and Comparative Example 3, respectively. The properties of Examples 1-3 and Comparative Examples 1-3 were tested according to the provisions of GB / T11175-2002 and HG / T2727-2010, and the obtained data are recorded in the following table:

[0045] Among them, in the storage stability test, the thickening property is qualified if neither hot storage nor cold storage affects the thickening property. In the thickening storage stability test, the paste is qualified if there is no resistance to stirring after hot storage and cold storage.

[0046] It can be seen from the data in the above table that the performance of the self-thickening acetic acid acrylate emulsion in Examples 1-3 is significantly better than that in Comparative Examples 1-3, indicating that the modified mesoporous titanium dioxide, modified starch and cross-linking monomer added in the present invention can improve the performance of the acetic acid acrylate emulsion. Therefore, the self-thickening acetic acid acrylate emulsion and the preparation method thereof provided by the present invention have excellent market promotion value and excellent market application prospects.

[0047] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0048] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A self-thickening acetic acid acrylate emulsion, characterized in that: The self-thickening vinyl acetate emulsion is composed of the following components: modified mesoporous titanium dioxide, modified starch, vinyl acetate, alkyl acrylate monomers, acrylic acid hydrophilic monomers, cross-linking monomers, emulsifier components, buffer components, initiator components and deionized water; The modified mesoporous titanium dioxide is prepared by modifying the mesoporous titanium dioxide with polyethyleneimine; The modified starch is prepared by oxidatively modifying cassava starch.

2. A self-thickening acetoacrylic emulsion according to claim 1, characterized in that: The preparation steps of the mesoporous titanium dioxide are: Step 1, weigh 4-5g of hexadecyltrimethylammonium bromide and 48mL of deionized water into a flask, add 36g of tetrabutyl titanate and stir at 300r / min for 2h, then add 10g of deionized water and 36g of anhydrous ethanol and stir at 200r / min for 3h under condensation reflux conditions at 88°C, cool to room temperature, filter and wash with deionized water three times, and then dry in an oven at 80°C to constant weight, the obtained product is recorded as crude titanium dioxide; Step 2: Pour 3 mL of 36% hydrochloric acid solution into 30 mL of 80% ethanol aqueous solution, add 5-8 g of crude titanium dioxide under stirring at a speed of 200 r / min, continue stirring for 48 hours, filter and wash with deionized water three times, place in an oven at 60°C and dry for 4 hours to obtain mesoporous titanium dioxide.

3. A self-thickening acetoacrylic emulsion according to claim 1, characterized in that: The preparation method of the modified mesoporous titanium dioxide is as follows: 2-3g of mesoporous titanium dioxide is weighed and dispersed in 100mL of anhydrous ethanol, 1-2g of polyethyleneimine is added after ultrasonic dispersion at a frequency of 28kHz for 30min, and then heated to 58°C and stirred at a speed of 200r / min for 8h, and finally centrifuged at a speed of 6000r / min for 20min, and the resulting precipitate is the modified mesoporous titanium dioxide.

4. The self-thickening acetoacrylic emulsion according to claim 1, characterized in that: The preparation method of the modified starch is as follows: weigh 12-15g of cassava starch and dissolve it in 50g of deionized water, dropwise add 20% sodium hydroxide aqueous solution to adjust the pH value to 10, then add 3-5g of hydrogen peroxide, stir at a speed of 300r / min for 10min, then heat to 50-60°C and keep warm for 40-60min, and the obtained product is the modified starch.

5. The self-thickening acetoacrylic emulsion according to claim 1, characterized in that: The alkyl acrylate monomer is at least one of isooctyl acrylate, ethyl acrylate, butyl acrylate, methyl acrylate, lauryl acrylate, n-propyl acrylate and 2-ethylhexyl methacrylate; the olefinic acid hydrophilic monomer is at least one of acrylic acid, hydroxyethyl acrylate, methacrylic acid, itaconic acid and hydroxypropyl acrylate; the crosslinking monomer is at least one of vinyl trimethoxy silane, glycidyl acrylate, γ-methacryloxypropyl trimethoxy silane, dimethylaminoethyl methacrylate and trimethylolpropane triacrylate.

6. The self-thickening acetoacrylic emulsion according to claim 1, characterized in that: The emulsifier component is prepared by mixing an anionic emulsifier and a nonionic emulsifier in a weight ratio of 1-10:1-10, the anionic emulsifier is at least one of sodium dodecylbenzene sulfonate, sodium dodecyl diphenyl ether disulfonic acid, sodium lauryl sulfate, sodium acrylamide-2-methylpropane sulfonate, sodium vinyl sulfonate and dialkyl-2-sulfosuccinate sodium, and the nonionic emulsifier is at least one of lauryl oleyl alcohol polyoxyethylene ether, stearyl alcohol polyoxyethylene ether, polyoxyethylene sorbitan monooleate and fatty alcohol polyoxyethylene ether.

7. The self-thickening acetoacrylic emulsion according to claim 1, characterized in that: The buffer component is at least one of sodium bicarbonate, ammonium bicarbonate, disodium hydrogen phosphate, sodium carbonate, ammonium carbonate and sodium acetate, and the initiator component is at least one of ammonium persulfate, sodium persulfate and potassium persulfate.

8. The method for preparing a self-thickening acetoacrylic emulsion according to any one of claims 1 to 7, characterized in that: The preparation method is: S1. Weigh 6-8 parts of modified mesoporous titanium dioxide, 8-12 parts of modified starch, 70-100 parts of vinyl acetate, 20-50 parts of alkyl acrylate monomers, 1-5 parts of acrylic acid hydrophilic monomers, 0.5-2 parts of cross-linking monomers, 3-4 parts of emulsifier components, 0.5-1 parts of buffer components and 100-130 parts of deionized water by weight, mix them, and mix and disperse them uniformly to obtain a pre-emulsion; S2, 0.5-2 parts by weight of the initiator component and 10 parts by weight of deionized water are mixed, and the mixture obtained after mixed dissolution is recorded as the initiator solution; S3, weighing 1-4 parts of emulsifier component and 0.5-1 parts of buffer component by weight, pouring into the reaction kettle, heating to 60-80°C, adding dropwise 0.5%-5% of the total amount of pre-emulsion and 30% of the total amount of initiator solution, and reacting for 10-30 minutes, the result is recorded as the reaction system; S4. Raise the temperature of the reaction system in the reactor to 60-80°C, then drop the remaining pre-emulsion and the remaining initiator solution, keep the mixture warm for 1-2h, cool it to 50°C and filter it, to obtain a self-thickening acetic acid propylene emulsion.

9. The method for preparing a self-thickening acetoacrylic emulsion according to claim 8, characterized in that: In S1, the specific operation of mixing and dispersing uniformly is stirring at a speed of 500 r / min for 10 min, and in S2, the specific operation of mixing and dissolving is stirring at a speed of 500 r / min for 5 min.

10. The method for preparing a self-thickening acetoacrylic emulsion according to claim 8, characterized in that: The dripping rate in S3 and S4 is 1 drop / s.

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