Disclosure of Invention
The invention provides a silicon dioxide/polyacrylate/polysiloxane composite emulsion, a preparation method and application thereof, wherein particles in the silicon dioxide/polyacrylate/polysiloxane composite emulsion comprise an inorganic silicon dioxide component, and polysiloxane is assembled on the surface of acrylate in a raspberry shape, so that the prepared emulsion has the advantages of high hardness, good stain resistance, strong aging resistance and excellent color retention after film forming.
Scheme I)
A preparation method of silicon dioxide-acrylate-polysiloxane composite emulsion mainly comprises the following steps:
firstly, modifying silica sol: uniformly mixing water and the silica sol, adding a silane coupling agent, and stirring at the temperature of 50-65 ℃ and the stirring speed of 200-400rpm for 3-6h to obtain the modified silica sol, wherein the mass ratio of the water to the silica sol to the silane coupling agent is 1-2:1-2: 0.03-0.1;
secondly, preparing silicon dioxide/acrylate core-shell structure emulsion:
uniformly mixing 9-18 parts by mass of deionized water and 0.45-2.5 parts by mass of emulsifier, slowly adding 28-40 parts by mass of acrylic monomer at the stirring speed of 300-600rpm, and continuously stirring for 10-30 minutes to form a pre-emulsion I;
uniformly mixing 2.25-4.5 parts by mass of deionized water and 0.11-0.23 part by mass of emulsifier, slowly adding 7-10 parts by mass of acrylic monomer and 1-3 parts by mass of functional monomer at the stirring speed of 300-600rpm, and continuously stirring for 10-30 minutes to form a second pre-emulsion;
dissolving 3-6 parts by mass of initiator in 3.3-6.6 parts by mass of water in the formula to form a first initiator aqueous solution; dissolving 1-2 parts by mass of an initiator in the formula in 0.45-0.9 part by mass of water to form a second initiator aqueous solution;
adding 25-40 parts by mass of the modified silica sol prepared in the step one, 0.5-2 parts by mass of sodium bicarbonate and 0.19-0.38 part by mass of emulsifier into a reaction kettle, uniformly stirring, heating to 80-85 ℃, simultaneously adding 3-10% of a first pre-emulsion and a second initiator aqueous solution, and preserving heat for 10-30 min; then, dripping the residual pre-emulsion I prepared in the first step and 80 percent of the first initiator aqueous solution prepared in the third step for 2 to 3 hours, and preserving heat for 20 to 30 minutes after finishing dripping;
fifthly, dripping the pre-emulsion II prepared in the step II and the first initiator aqueous solution prepared in the step III in a proportion of 20 percent for 1 to 1.5 hours;
sixthly, preserving the heat for 1 hour after the dropwise adding is finished, then cooling to 30-40 ℃, and adjusting the pH value of the system to 7-8 to obtain silicon dioxide/acrylate core-shell structure emulsion;
thirdly, preparing the silicon dioxide/acrylate/polysiloxane composite emulsion: at room temperature, dripping the organic silicon emulsion into the silicon dioxide/acrylate composite emulsion prepared in the second step, and reacting for 3-12h at the temperature of 25-90 ℃ to obtain the silicon dioxide/acrylate/polysiloxane composite emulsion; the mass ratio of the organic silicon emulsion to the silicon dioxide/acrylate composite emulsion prepared in the second step is 1: 5-1: 30, of a nitrogen-containing gas;
preferably, the silane coupling agent in the first step is one or a combination of more than two of KH-570, KH560, KH550, A-151 or A-171 in any proportion.
Preferably, the silica sol in the first step has a particle size of 20-35nm, a solid content of 30-40% and a pH of 4-6.
Preferably, the acrylic acid monomer in the second step is one or a combination of more than two of methyl methacrylate, butyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, methacrylic acid and acrylic acid in any proportion.
Preferably, the functional monomer in the second step is one or a combination of more than two of glycidyl methacrylate, acrylamide, urea hydroxymethyl acrylate or organosilicon monomer in any proportion.
Preferably, the emulsifier in the second step is formed by mixing anion, nonionic and polymerizable emulsifier according to the mass ratio of 1-2:1-2: 1-2.
Preferably, the anionic emulsifier is one or any combination of more than two of DNS-18, DNS-625, SW3001 or FSL 707; the non-ionic emulsifier is one or the random combination of more than two of DNS-900, 3016 or LGE-30; the polymerizable emulsifier is one or more of HAPS, SR-10 and ER-10-in any combination.
Preferably, the particle size of the organic silicon emulsion is 20-150nm, the solid content is 30-50%, and the organic silicon emulsion is modified by amino or epoxy groups.
Scheme two)
The silicon dioxide-acrylate-polysiloxane composite emulsion is prepared by the method.
The application of the silicon dioxide-acrylate-polysiloxane composite emulsion in the exterior wall building coating comprises 10-30% of the emulsion prepared by the method by mass fraction.
Compared with the prior art, the preparation method of the silica/acrylate/polysiloxane composite emulsion, disclosed by the invention, has the advantages that the silica sol is modified, then the composite emulsion with a more stable silica/acrylate system and a low gel rate (less than 0.5%) is prepared by utilizing a seed-growth polymerization method, and active groups such as amino and epoxy are introduced into the acrylate, so that the acrylate and the subsequently added polysiloxane nano particles can be effectively assembled and compounded, and thus raspberry-shaped silica/acrylate/polysiloxane organic-inorganic hybrid emulsion with excellent performance is prepared. The silica component provides hardness support in the particles of the emulsion; the acrylate provides film-forming properties; polysiloxanes provide weatherability, color retention and stain resistance. The method is simple to operate, the cost performance of the selected raw materials is high, all the working procedures can be continuously completed, and the additional production burden cannot be increased.
Detailed Description
The invention will be further illustrated and explained with reference to specific embodiments, but the scope of protection is not limited to the following embodiments.
Example 1
A preparation method of silicon dioxide-acrylate-polysiloxane composite emulsion mainly comprises the following steps:
firstly, modifying silica sol: uniformly mixing water and silica sol, adding a silane coupling agent, and stirring at the stirring speed of 400rpm for 6 hours at 50 ℃ to obtain modified silica sol; the mass ratio of the water to the silica sol to the silane coupling agent is 1:1: 0.1;
secondly, preparing silicon dioxide/acrylate core-shell structure emulsion:
uniformly mixing 9 parts by mass of deionized water and 0.45 part by mass of an emulsifier, then slowly adding 28 parts by mass of an acrylic monomer at a stirring speed of 300rpm, and then continuously stirring for 10 minutes to form a pre-emulsion I;
uniformly mixing 2.25 parts by mass of deionized water and 0.11 part by mass of emulsifier, slowly adding 7 parts by mass of acrylic monomer and 1 part by mass of functional monomer at the stirring speed of 300rpm, and continuously stirring for 10 minutes to form a second pre-emulsion;
dissolving 3 parts by mass of initiator in 3.3 parts by mass of water in the formula to form a first initiator aqueous solution; dissolving 1 part by mass of an initiator in 0.45 part by mass of water to form a second initiator aqueous solution;
adding 25 parts by mass of the modified silica sol prepared in the step one, 0.5 part by mass of sodium bicarbonate and 0.19 part by mass of emulsifier into a reaction kettle, uniformly stirring, heating to 80 ℃, simultaneously adding 3% of a first pre-emulsion and a second initiator aqueous solution, and keeping the temperature for 10 min; then, dripping the residual pre-emulsion I prepared in the first step and 80 percent of the first initiator aqueous solution prepared in the third step for 2 hours, and preserving heat for 20 minutes after finishing dripping;
fifthly, dripping the pre-emulsion II prepared in the step II and the first initiator aqueous solution prepared in the step III in a proportion of 20 percent for 1 hour;
sixthly, preserving the heat for 1 hour after the dropwise adding is finished, then cooling to 30 ℃, and adjusting the pH value of the system to 7 to obtain silicon dioxide/acrylate core-shell structure emulsion;
thirdly, preparing the silicon dioxide/acrylate/polysiloxane composite emulsion: at room temperature, dripping the organic silicon emulsion into the silicon dioxide/acrylate composite emulsion prepared in the second step, and reacting for 3 hours at the temperature of 25 ℃ to obtain silicon dioxide/acrylate/polysiloxane composite emulsion; the mass ratio of the organic silicon emulsion to the silicon dioxide/acrylate composite emulsion prepared in the step two is 1.5: 30, of a nitrogen-containing gas;
preferably, the silane coupling agent in the first step is KH 550.
Preferably, the silica sol in the first step has a particle size of 20nm, a solid content of 30% and a pH of 4.
Preferably, the acrylic acid monomer in step two is butyl acrylate.
Preferably, the functional monomer in step two is glycidyl methacrylate.
Preferably, the emulsifier in the second step is formed by mixing anion, nonionic and polymerizable emulsifier according to the mass ratio of 1:1: 1.
Preferably, the anionic emulsifier is DNS-18; the nonionic emulsifier is DNS-900; the polymerizable emulsifier is HAPS.
Preferably, the particle size of the organic silicon emulsion is 20-150nm, the solid content is 30-50%, and the organic silicon emulsion is modified by amino or epoxy groups.
Coating the glass plate with the wire bar silicon dioxide/acrylic ester/polysiloxane composite emulsion, wherein the wet film thickness is 200 micrometers, baking the glass plate for 1 hour at 70 ℃, and testing the performance when the film coating temperature is reduced to room temperature. The hardness of a coating pencil is F, the adhesion force on glass is 0-1 grade, the water contact angle is 115 degrees, the water resistance and water-white resistance are excellent (no water-white and foaming exist in 4 days), and the coating pencil is resistant to artificial aging and has no chalking after 600 hours.
Example 2
A preparation method of silicon dioxide-acrylate-polysiloxane composite emulsion mainly comprises the following steps:
firstly, modifying silica sol: uniformly mixing water and silica sol, adding a silane coupling agent, and stirring at 65 ℃ and the stirring speed of 200rpm for 3 hours to obtain modified silica sol; the mass ratio of the water to the silica sol to the silane coupling agent is 2: 2: 0.03
Secondly, preparing silicon dioxide/acrylate core-shell structure emulsion:
uniformly mixing 18 parts by mass of deionized water and 2.5 parts by mass of an emulsifier, slowly adding 40 parts by mass of an acrylic monomer at a stirring speed of 600rpm, and continuing for 30 minutes to form a pre-emulsion I;
uniformly mixing 4.5 parts by mass of deionized water and 0.23 part by mass of emulsifier, slowly adding 10 parts by mass of acrylic monomer and 3 parts by mass of functional monomer at a stirring speed of 600rpm, and continuously stirring for 30 minutes to form a second pre-emulsion;
dissolving 6 parts by mass of an initiator in 6.6 parts by mass of water to form a first initiator aqueous solution; dissolving 2 parts by mass of an initiator in 0.9 part by mass of water in the formula to form a second initiator aqueous solution;
adding 40 parts by mass of the modified silica sol prepared in the step one, 1 part by mass of sodium bicarbonate and 0.38 part by mass of emulsifier into a reaction kettle, uniformly stirring, heating to 85 ℃, simultaneously adding 10% of a first pre-emulsion and a second initiator aqueous solution, and keeping the temperature for 30 min; then, dripping the residual pre-emulsion I prepared in the first step and 80 percent of the first initiator aqueous solution prepared in the third step for 3 hours, and preserving heat for 30 minutes after finishing dripping;
fifthly, dripping the pre-emulsion II prepared in the step II and the first initiator aqueous solution prepared in the step III in a proportion of 20 percent for 1.5 hours;
sixthly, preserving the heat for 1 hour after the dropwise adding is finished, then cooling to 40 ℃, and adjusting the pH value of the system to 8 to obtain silicon dioxide/acrylate core-shell structure emulsion;
thirdly, preparing the silicon dioxide/acrylate/polysiloxane composite emulsion: at room temperature, dripping the organic silicon emulsion into the silicon dioxide/acrylate composite emulsion prepared in the second step, and reacting for 12 hours at the temperature of 90 ℃ to obtain the silicon dioxide/acrylate/polysiloxane composite emulsion; the mass ratio of the organic silicon emulsion to the silicon dioxide/acrylate composite emulsion prepared in the step two is 1: 30, of a nitrogen-containing gas;
preferably, the silane coupling agent in step one is A-171.
Preferably, the silica sol in the first step has a particle size of 20-35nm, a solid content of 30-40% and a pH of 4-6.
Preferably, the acrylic monomer in step two is methyl methacrylate.
Preferably, the functional monomer in step two is glycidyl methacrylate.
Preferably, the emulsifier in the second step is formed by mixing anion, nonionic and polymerizable emulsifier according to the mass ratio of 2:1: 1.
Preferably, the anionic emulsifier is FSL 707; the nonionic emulsifier is LGE-30; the polymerizable emulsifier is one of ER-10-.
Preferably, the particle size of the organic silicon emulsion is 20-150nm, the solid content is 30-50%, and the organic silicon emulsion is modified by amino or epoxy groups.
The wire rod silicon dioxide/acrylic ester/polysiloxane composite emulsion is coated on a glass plate, the thickness of a wet film is 200 micrometers, the film is baked for 1 hour at 70 ℃, the light transmittance of the film is excellent, and the performance is tested when the temperature of the film is reduced to room temperature. The hardness of a coating pencil is H, the adhesion force on glass is 0-1 grade, the water contact angle is 110 degrees, the water resistance and water-white resistance are excellent (no water-white and foaming exist in 4 days), and the coating pencil is resistant to artificial aging and has no chalking after 500 hours.
Example 3
25g of deionized water was added to 25g of acidic silica sol (solid content: 40%), heated to 60 ℃ and added with 0.6gKH570, and the mixture was stirred at 250rpm and kept warm for 5 hours to obtain modified silica sol (solid content: 20%).
20g of water, 2g S25 and 2g of FSL707 were put into a 250ml four-necked flask, and after stirring at room temperature and 250rpm, 1.6g of acrylic acid, 45g of methyl methacrylate and 30g of butyl acrylate were added thereto, and the mixture was stirred at 400rpm for 20 minutes to obtain a uniform and stable pre-emulsion 1.
6g of water, 0.3g S25, 0.4g of FSL707 and 0.3g N-10 were put into a 100ml four-necked flask, and after stirring uniformly at 250rpm at normal temperature, 0.4g of acrylic acid, 2g of methylol ureide, 1.5g of an organosilicon monomer UM-1770, 2g of glycidyl methacrylate, 10g of methyl methacrylate and 8g of butyl acrylate were added in this order, the stirring speed was adjusted to 400rpm, and after stirring for 20 minutes, a uniform and stable pre-emulsion 2 was obtained.
5g of water and 0.2g of sodium hydrogencarbonate were put in a 500ml four-necked flask (equipped with a condenser and a thermometer), and after dissolving them by stirring, 2g S25 and 0.5g of FSL707 were added, and after stirring for 5 minutes, 50g of the above-mentioned modified silica sol was added to the flask and stirred at room temperature for 30 minutes. Then the temperature was raised to 82 ℃ with stirring at 250rpm, after the temperature had stabilized, 3g of the above pre-emulsion 1 and 1g of an aqueous ammonium persulfate initiator solution (containing 0.08g of ammonium persulfate) were added and the temperature was maintained for 20 min. The bottle was filled dropwise over 3h with the remaining pre-emulsion 1 and 10g of aqueous initiator solution (containing 0.4g of ammonium persulfate) and incubated for 30 min. And continuously dropwise adding 2g of pre-emulsion and 2g of initiator aqueous solution (containing 0.08g of ammonium persulfate) into the reaction flask within 1h, reacting for 1h after dropwise adding, cooling, and adjusting the pH of the system to 7-8 by using DMEA to prepare the silicon dioxide/acrylate composite emulsion.
Introducing 25g of commercial amino modified organic silicon emulsion (with the particle size of 40nm and the solid content of 37%) into the composite emulsion, diluting the organic silicon emulsion by 2 times, dropwise adding the diluted organic silicon emulsion into the silicon dioxide/acrylate composite emulsion, controlling the dropwise adding within 2h, keeping the temperature at 80 ℃ for 5 hours, cooling, and adjusting the pH to 7-8 by using DMEA to obtain the silicon dioxide/acrylate/polysiloxane composite emulsion.
Coating the glass plate with the wire bar silicon dioxide/acrylic ester/polysiloxane composite emulsion, wherein the wet film thickness is 200 micrometers, baking the glass plate for 1 hour at 70 ℃, and testing the performance when the film coating temperature is reduced to room temperature. The hardness of a coating pencil is 2H, the adhesive force on glass is 0-1 grade, the water contact angle is 125 degrees, the water resistance and the water-white resistance are excellent (no water white and bubbling in 4 days), and the coating pencil is resistant to artificial aging and has no chalking after 600 hours.
Example 4
25g of deionized water was added to 25g of acidic silica sol (solid content: 40%), the temperature was raised to 50 ℃ and 1g of A151 was added thereto, and the mixture was stirred at 250rpm and kept warm for 3 hours to obtain a modified silica sol (solid content: 20%).
20g of water, 2g S25 and 2g of FSL707 were put into a 250ml four-necked flask, and after stirring at room temperature and 250rpm, 1.6g of acrylic acid, 30g of methyl methacrylate and 45g of butyl acrylate were added thereto, and the mixture was stirred at 400rpm for 20 minutes to obtain a uniform and stable pre-emulsion 1.
6g of water, 0.3g S25, 0.4g of FSL707, and 0.3g N-10 were put into a 100ml four-necked flask, and after stirring at 250rpm at normal temperature, 0.4g of acrylic acid, 2g of methylol ureide, 1.5g of silicone monomer UM-1770, 1g of acrylamide, 7g of methyl methacrylate, and 11g of butyl acrylate were added in this order, and the stirring speed was adjusted to 400rpm, and after stirring for 20 minutes, homogeneous and stable pre-emulsion 2 was obtained.
5g of water and 0.2g of sodium hydrogencarbonate were put in a 500ml four-necked flask (equipped with a condenser and a thermometer), and after dissolving them by stirring, 2g S25 and 0.5g of FSL707 were added, and after stirring for 5 minutes, 50g of the above-mentioned modified silica sol was added to the flask and stirred at room temperature for 30 minutes. Then the temperature was raised to 82 ℃ with stirring at 250rpm, after the temperature had stabilized, 5g of the above pre-emulsion 1 and 1g of an aqueous ammonium persulfate initiator solution (containing 0.08g of ammonium persulfate) were added and the temperature was maintained for 20 min. The bottle was filled dropwise over 3h with the remaining pre-emulsion 1 and 10g of aqueous initiator solution (containing 0.4g of ammonium persulfate) and incubated for 30 min. And continuously dropwise adding 2g of pre-emulsion and 2g of initiator aqueous solution (containing 0.08g of ammonium persulfate) into the reaction flask within 1h, reacting for 1h after dropwise adding, cooling, and adjusting the pH of the system to 7-8 by using DMEA to prepare the silicon dioxide/acrylate composite emulsion.
And (2) introducing 13g of self-made epoxy modified organic silicon emulsion (with the particle size of 50nm and the solid content of 42%) into the composite emulsion, diluting the organic silicon emulsion by 3 times, dropwise adding the diluted organic silicon emulsion into the emulsion, controlling the dropwise adding time within 2 hours, heating to 70 ℃, preserving the heat for 5 hours, and reducing the temperature to adjust the pH to 7-8 by using DMEA to obtain the silicon dioxide/acrylate/polysiloxane composite emulsion.
The wire rod silicon dioxide/acrylic ester/polysiloxane composite emulsion is coated on a glass plate, the thickness of a wet film is 200 micrometers, the film is maintained for 7 days at room temperature, the light transmittance of the film is excellent, and the performance is tested when the temperature of the film is reduced to room temperature. The hardness of the coating pencil is H, the adhesion force on glass is 0-1 grade, the water contact angle is 115 degrees, the water resistance and water-white resistance are excellent (no water-white and foaming exist in 4 days), and the coating pencil is resistant to artificial aging and has no chalking after 400 hours.
Example 5
Adding 25g of deionized water into 25g of acidic silica sol (solid content: 40%), heating to 55 ℃, adding 1gA-171, stirring at 250rpm, and keeping the temperature for 5 hours to obtain modified silica sol (solid content: 20%).
20g of water, 2g S25 and 1.8g of DNS-18 were put into a 250ml four-necked flask, and after stirring at 250rpm at normal temperature, 1.6g of acrylic acid, 30g of methyl methacrylate and 45g of butyl acrylate were added thereto, and the mixture was stirred at 400rpm for 20 minutes to obtain a uniform and stable pre-emulsion 1.
6g of water, 0.3g S25, 0.1g of DNS-900 and 0.3g N-10 were put into a 100ml four-necked flask, and after stirring uniformly at 250rpm at normal temperature, 0.4g of acrylic acid, 2g of methylol ureide, 0.5g of silicone monomer KH570, 2g of acrylamide, 7g of methyl methacrylate and 11g of butyl acrylate were added in this order, the stirring speed was adjusted to 400rpm, and after stirring for 20 minutes, uniform and stable pre-emulsion 2 was obtained.
5g of water and 0.2g of sodium hydrogencarbonate were put in a 500ml four-necked flask (equipped with a condenser and a thermometer), and after dissolving them by stirring, 2g S25 and 0.5g of DNS-18 were added, and after stirring for 5 minutes, 50g of the above-mentioned modified silica sol was added to the flask and stirred at room temperature for 30 minutes. Then the temperature was raised to 82 ℃ with stirring at 250rpm, after the temperature had stabilized, 8g of the above pre-emulsion 1 and 1g of an aqueous ammonium persulfate initiator solution (containing 0.08g of ammonium persulfate) were added and the temperature was maintained for 20 min. The bottle was filled dropwise over 3h with the remaining pre-emulsion 1 and 10g of aqueous initiator solution (containing 0.4g of ammonium persulfate) and incubated for 30 min. And continuously dropwise adding 2g of pre-emulsion and 2g of initiator aqueous solution (containing 0.08g of ammonium persulfate) into the reaction flask within 1h, reacting for 1h after dropwise adding, cooling, and adjusting the pH of the system to 7-8 by using DMEA to prepare the silicon dioxide/acrylate composite emulsion.
Introducing 26g of self-made epoxy modified organic silicon emulsion (with the particle size of 50nm and the solid content of 42%) into the composite emulsion, diluting the organic silicon emulsion by 2 times, dropwise adding the diluted organic silicon emulsion into the emulsion, controlling the dropwise adding time within 4 hours, reacting at room temperature for 12 hours, and adjusting the pH to 7-8 by using DMEA to obtain the silicon dioxide/acrylate/polysiloxane composite emulsion.
The wire rod silicon dioxide/acrylic ester/polysiloxane composite emulsion is coated on a glass plate, the thickness of a wet film is 200 micrometers, the film is maintained for 7 days at room temperature, the light transmittance of the film is excellent, and the performance is tested when the temperature of the film is reduced to room temperature. The hardness of a coating pencil is H, the adhesion force on glass is 0-1 grade, the water contact angle is 130 degrees, the water resistance and water-white resistance are excellent (no water-white and foaming exist in 4 days), and the coating pencil is resistant to artificial aging and has no chalking after 800 hours.
Example 6
In contrast to example 5, example 6 contained no silica and no polysiloxane particles, and the emulsion prepared was comparative. Wherein the modified silica sol dispersion is replaced by equivalent deionized water and no organosilicon emulsion is added subsequently; the other experimental formulations and procedures were the same as in example 5.
The amino modified silicone emulsion described in the above example is a mezzanine Y-20746, and the epoxy modified silicone emulsion is a self-made (prepared by emulsifying epoxy modified silicone oil);
the silica-acrylate-polysiloxane composite emulsion prepared in the above examples 1-6 is prepared into a coating in an exterior wall building coating according to the following formula, and then a plate making test is carried out according to GB/T9755-2014, which is specifically shown in Table 1, and the thickening agent is preferably Rohm and Haas ASE 60; the defoaming agent is preferably hamming DF 7035; the pH regulator is preferably MA-95; the titanium dioxide is preferably DuPont R706; the film-forming auxiliary agent is preferably alcohol ester twelve; the sterilizing and preserving agent is preferably the dragon sand Proxel G20. The coating can also contain other emulsions with the mass fraction of 10-30%, and the performance of the coating is excellent.
The adopted basic formula comprises the following specific components in parts by weight:
TABLE 1 Properties of the paints prepared using the emulsions of examples 1-6