A water-based acrylic exterior wall emulsion and a preparation method thereof

Abstract

The application discloses a water-based acrylic outer wall emulsion and a preparation method thereof, and belongs to the technical field of building coating. The water-based acrylic outer wall emulsion comprises methyl methacrylate, butyl acrylate, acrylic acid, a styrene-maleic anhydride copolymer salt solution, methyl acrylamide, itaconic acid and an emulsifier. The water-based acrylic outer wall emulsion has good film-forming performance, and the hydrophilicity and hardness of the paint film can be improved by using the hydrophilic hard monomer methyl methacrylate and the soft monomer butyl acrylate; the hydrophilicity of the paint film can be further improved by using the acrylic acid, the methyl acrylamide and the itaconic acid which have hydrophilic groups; in addition, the hardness of the paint film can be improved, and the hydrophilicity of the paint film can also be improved by introducing the special hydrophilic material, the styrene-maleic anhydride copolymer salt solution, so that the stain resistance of the paint film can be obviously improved by improving the hydrophilicity of the paint film.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of building coatings, in particular to a water-based acrylic exterior wall emulsion and a preparation method thereof. BACKGROUND

[0002] The exterior wall flat coating latex paint is the largest variety in exterior wall decorative coatings, and its stain resistance is facing great challenges. If the wall is dirty, the cleaning cost and recoating cost of the wall are very high, so people hope that the exterior wall flat coating latex paint can be more resistant to dirt after being brushed on the wall, that is, the stain resistance of the film after the exterior wall flat coating latex paint is formed can be improved.

[0003] At present, the stain resistance of the film after the exterior wall flat coating latex paint is formed is mainly improved by improving the hydrophobicity of the paint film. The principle is to reduce the surface tension of the paint film, so that the dust stains and the like cannot accumulate on the surface of the paint film after the paint film has the lotus leaf effect. When the rainwater contacts the surface of the paint film, it will pass through the surface of the paint film in the form of a small water droplet like the rainwater on the surface of the lotus leaf, and at the same time, the dust stains are taken away, achieving the effect of cleaning the surface of the paint film. However, through actual verification, the effect of improving the stain resistance of the paint film by improving the hydrophobicity of the paint film is limited. This method can only make the surface of the paint film clean when it rains heavily after the dust cannot easily accumulate in the early stage; when it rains lightly, a clear and clean path is formed, and the path where the rainwater rolls is clean, and the path where the rainwater does not roll is dirty. However, especially importantly, the hydrophobic surface of the paint film cannot prevent dust from accumulating for a long time. Within one to two years after the exterior wall flat coating latex paint is applied to the exterior wall, dust can already accumulate on the surface of the paint film. After the dust accumulates on the hydrophobic surface of the paint film, it cannot be washed away no matter whether it rains lightly or heavily, which means that the hydrophobic surface of the paint film will gradually become dirty in about one to two years and cannot be washed.

[0004] It can be seen that the prior art still needs to be improved and enhanced. SUMMARY

[0005] In view of the above shortcomings of the prior art, the purpose of the present application is to provide a water-based acrylic exterior wall emulsion and a preparation method thereof, which aims to improve the stain resistance of the paint film by improving the hydrophilicity of the paint film after the exterior wall flat coating latex paint is formed.

[0006] In order to achieve the above purpose, the present application adopts the following technical solutions:

[0007] The present application provides a water-based acrylic exterior wall emulsion, which comprises the following components by weight: 80-100 parts of methyl methacrylate and butyl acrylate, 2-5 parts of acrylic acid, 1-6 parts of styrene-maleic anhydride copolymer salt solution, 1-3 parts of methacrylamide, 1-3 parts of itaconic acid, 1.5-2 parts of emulsifier, 0.5-2 parts of initiator, and 100 parts of deionized water.

[0008] The solid content of the styrene-maleic anhydride copolymer salt solution is 40±1%.

[0009] The styrene-maleic anhydride copolymer salt solution in the water-based acrylic exterior wall emulsion is a styrene-maleic anhydride copolymer sodium salt solution.

[0010] The weight ratio of styrene and maleic anhydride in the styrene-maleic anhydride copolymer sodium salt solution in the water-based acrylic exterior wall emulsion is 1:1.

[0011] The methyl methacrylate accounts for 55% of the total weight of methyl methacrylate and butyl acrylate in the water-based acrylic exterior wall emulsion. ～ 67%.

[0012] The emulsifier in the water-based acrylic exterior wall emulsion includes one or both of polyoxyethylene-polyoxypropylene block copolymer and octadecanol polyoxyethylene ether.

[0013] The initiator in the water-based acrylic exterior wall emulsion includes one or more of ammonium persulfate, potassium persulfate, and sodium persulfate.

[0014] The pH of the water-based acrylic exterior wall emulsion is 7.0 ～ 9.0.

[0015] The application also provides a preparation method of a water-based acrylic exterior wall emulsion, wherein the water-based acrylic exterior wall emulsion is the aforementioned water-based acrylic exterior wall emulsion, and the preparation method comprises the following steps:

[0016] Step S001. 40 parts of deionized water and 0.5 ～ 0.7 parts of emulsifier are added to a reaction kettle to prepare a bottom liquid;

[0017] Step S002. 30 parts of deionized water and 1 ～ 1.3 parts of emulsifier are added to an emulsifying cylinder, and after stirring, 50-60 parts of methyl methacrylate, 30-40 parts of butyl acrylate, 2-5 parts of acrylic acid, 1-3 parts of methacrylamide, and 1-3 parts of itaconic acid are sequentially added, and after stirring and mixing, a pre-emulsion is prepared;

[0018] Step S003. 30 parts of deionized water and 0.5-2 parts of initiator are stirred and mixed to prepare an initiator solution;

[0019] Step S004. The temperature in the reaction kettle is raised to 80-88 DEG C, and 4-8% of the total amount of pre-emulsion and 10-30% of the total amount of initiator solution are added to the bottom liquid, and after 20-30 min of incubation, a seed emulsion is prepared, and the remaining pre-emulsion and initiator solution are added to the reaction kettle at a uniform speed for 150-240 min.

[0020] Step S005. After step S004, the temperature in the reaction kettle is maintained at 80-88 DEG C for 50-70 min, and after the incubation, the temperature in the reaction kettle is reduced to room temperature, and the pH of the liquid in the reaction kettle is adjusted with sodium hydroxide solution, and then 1-6 parts of styrene-maleic anhydride copolymer salt solution is added, and the liquid in the reaction kettle is stirred for 20-40 min; after stirring, the liquid in the reaction kettle is filtered to obtain a water-based acrylic exterior wall emulsion.

[0021] Further, in step S004, the remaining initiator solution is added 10 min later than the remaining pre-emulsion.

[0022] Beneficial effects:

[0023] The present application provides a water-based acrylic exterior wall emulsion and a preparation method thereof, by using the more hydrophilic hard monomer methyl methacrylate and soft monomer butyl acrylate, the water-based acrylic exterior wall emulsion has good film-forming properties, and the hydrophilicity and hardness of the paint film are improved; by using acrylic acid, methacrylamide and itaconic acid with hydrophilic groups, the hydrophilicity of the paint film is further improved; in addition, by introducing a special hydrophilic material, styrene-maleic anhydride copolymer salt solution, the hardness of the paint film is improved, and the hydrophilicity of the paint film is also improved. Since the hydrophilicity of the water-based acrylic exterior wall emulsion provided by the present application is improved after film formation, the paint containing the water-based acrylic exterior wall emulsion after film formation not only improves the dirt resistance of the paint film by improving the hardness of the paint film, but also significantly improves the dirt resistance of the paint film by improving the hydrophilicity of the paint film. DETAILED DESCRIPTION

[0024] The present application provides a water-based acrylic exterior wall emulsion and a preparation method thereof, in order to make the purpose, technical scheme and effect of the present application more clear and explicit, the following examples are further described in detail. It should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the present application.

[0025] The application provides an aqueous acrylic exterior wall emulsion, which comprises the following components in parts by weight: 80-100 parts of methyl methacrylate and butyl acrylate, 2-5 parts of acrylic acid, 1-6 parts of styrene-maleic anhydride copolymer salt solution, 1-3 parts of methacrylamide, 1-3 parts of itaconic acid, 1.5-2 parts of emulsifier, 0.5-2 parts of initiator and 100 parts of deionized water.

[0026] The solid content of the styrene-maleic anhydride copolymer salt solution is 40±1%.

[0027] In the above components, the methyl methacrylate is a hard monomer, which can make the emulsion and paint film have good hardness after film formation, thereby improving the stain resistance of the paint film; the butyl acrylate is a soft monomer, which has a lower glass transition temperature than the methyl methacrylate, and when used in combination with the methyl methacrylate, the glass transition temperature of the emulsion can be prevented from being too high due to the introduction of the hard monomer, so that the emulsion and paint have good film-forming performance at room temperature and the weather resistance of the paint film is improved. In addition, the methyl methacrylate and butyl acrylate are more hydrophilic than other hard monomers (such as styrene) and soft monomers (such as isooctyl acrylate), so that the hydrophilicity of the paint film can be improved.

[0028] In the above components, the acrylic acid contains a carboxyl group, the methacrylamide contains an amide group, and the itaconic acid has a double carboxylic acid structure and is highly hydrophilic, so that the hydrophilicity of the three functional monomers is better than that of the methyl methacrylate and butyl acrylate, and the introduction of the three functional monomers into the emulsion can further improve the hydrophilicity of the paint film.

[0029] In the above components, the styrene-maleic anhydride copolymer salt solution is a special hydrophilic material, the styrene part of which can improve the hardness of the paint film, and the double carboxyl structure of the maleic anhydride part can provide hydrophilicity for the paint film, so that the deficiency of the styrene part in hydrophilicity can be made up, and at the same time, the surface of the paint film can be easily wetted, the water flow can carry away the pollution source, and the effect of improving the stain resistance of the paint film can be achieved.

[0030] The application uses the more hydrophilic hard monomer methyl methacrylate and the soft monomer butyl acrylate to improve the film-forming property of the water-based acrylic exterior wall emulsion, and improve the hydrophilicity and hardness of the paint film; the use of the acrylic acid, methacrylamide and itaconic acid with hydrophilic groups can further improve the hydrophilicity of the paint film; in addition, the use of the special hydrophilic material, styrene-maleic anhydride copolymer salt solution, can improve the hardness of the paint film and the hydrophilicity of the paint film. The water-based acrylic exterior wall emulsion provided by the application has improved hydrophilicity, so that the surface tension of the paint film can be improved after the paint containing the water-based acrylic exterior wall emulsion is formed, so that the rainwater can quickly spread and wet the wall surface after contacting the paint film, and the dust and stains accumulated on the wall surface can be washed away with the rainwater, so that the effect of self-cleaning of the paint film surface is achieved.

[0031] Further, the styrene-maleic anhydride copolymer salt solution is a styrene-maleic anhydride copolymer sodium salt solution. Compared with the styrene-maleic anhydride copolymer potassium salt solution and the styrene-maleic anhydride copolymer ammonium salt solution, the styrene-maleic anhydride copolymer sodium salt solution is better in improving the stain resistance, washability and storage stability of the emulsion and the paint.

[0032] Further, the weight ratio of styrene to maleic anhydride in the styrene-maleic anhydride copolymer sodium salt solution is 1:1. When the weight ratio of the styrene part to the maleic anhydride part in the styrene-maleic anhydride copolymer sodium salt solution is 1:1, the stain resistance of the paint film is most obviously improved.

[0033] Further, the methyl methacrylate accounts for 55% of the total weight of the methyl methacrylate and the butyl acrylate. ～ 67%. Although the methyl methacrylate can improve the hardness of the emulsion and the paint after film formation, when the amount of the methyl methacrylate is too large, the film-forming property of the emulsion and the paint is poor, so the amount of the methyl methacrylate cannot be too large. Therefore, in the present application, the amount of the methyl methacrylate accounts for 55% of the total weight of the methyl methacrylate and the butyl acrylate. ～ 67% is the best, at which the film-forming property of the emulsion and the paint is good, and the stain resistance and washability of the paint film can be kept at the best.

[0034] Further, the emulsifier includes one or both of polyoxyethylene-polyoxypropylene block copolymer and octadecanol polyoxyethylene ether. The above-mentioned emulsifier is a hydrophilic emulsifier, which can further improve the hydrophilicity of the emulsion and the paint.

[0035] Further, the initiator includes one or more of ammonium persulfate, potassium persulfate and sodium persulfate.

[0036] Further, the pH of the water-based acrylic exterior wall emulsion is 7.0-9.0. When the pH of the emulsion is 7.0-9.0, the water-based acrylic exterior wall emulsion and the paint containing the water-based acrylic exterior wall emulsion have the best storage stability.

[0037] The application also provides a preparation method of the water-based acrylic exterior wall emulsion.

[0038] Step S001. 40 parts of deionized water and 0.5-0.7 parts of emulsifier are added to a reaction kettle (the reaction kettle is provided with a stirring device, a condensing device and a constant-flow pump feeding device) to prepare a bottom liquid by stirring;

[0039] Step S002. 30 parts of deionized water and 1-1.3 parts of emulsifier are added to an emulsifying cylinder (provided with a metering device and a stirring device), and then 50-60 parts of methyl methacrylate, 30-40 parts of butyl acrylate, 2-5 parts of acrylic acid, 1-3 parts of methacrylamide and 1-3 parts of itaconic acid are sequentially added after uniform stirring, and then the mixture is uniformly stirred to prepare a pre-emulsion;

[0040] Step S003. 30 parts of deionized water is mixed with 0.5-2 parts of initiator to prepare an initiator solution;

[0041] Step S004. The temperature in the reaction kettle is raised to 80-88°C, and 4%-8% of the total amount of the pre-emulsion and 10%-30% of the total amount of the initiator solution are added to the bottom liquid, and then the seed emulsion is prepared after 20-30 minutes of heat preservation, and the remaining pre-emulsion and initiator solution are added dropwise to the reaction kettle at a uniform speed for 150-240 minutes;

[0042] Step S005. After the end of step S004, the temperature in the reaction kettle is maintained at 80-88°C for 50-70 minutes of heat preservation, and then the temperature in the reaction kettle is reduced to room temperature, and then 1-6 parts of a styrene-maleic anhydride copolymer salt solution is added, and the liquid in the reaction kettle is stirred for 20-40 minutes; after the stirring is completed, the liquid in the reaction kettle is filtered to obtain the water-based acrylic exterior wall emulsion.

[0043] Further, in step S004, the remaining initiator solution is added dropwise 10 minutes later than the remaining pre-emulsion, so that the residual monomers can be better reacted during the heat preservation process in step S005, and the amount of residual monomers is lower.

[0044] The water-based acrylic exterior wall emulsion prepared by the preparation method has solid content of 48.0%-50.0%, pH of 7.0-9.0, particle size of 150 nm-190 nm, and glass transition temperature of 25-35 DEG C, which meets the index parameters of mainstream exterior wall emulsion, and coating manufacturers can easily replace the emulsion without making large changes to the formula of the coating.

[0045] In order to further illustrate the water-based acrylic exterior wall emulsion and the preparation method thereof provided by the application, the following examples and comparative examples are provided.

[0046] Example 1

[0047] The water-based acrylic exterior wall emulsion provided by the application comprises the following components by weight: 58 parts of methyl methacrylate, 30 parts of butyl acrylate, 2 parts of acrylic acid, 1 part of styrene-maleic anhydride copolymer sodium salt solution, 3 parts of methacrylamide, 1 part of itaconic acid, 1.8 parts of sodium dodecyl alcohol polyoxyethylene ether sulfate, 0.5 parts of ammonium persulfate, and 100 parts of deionized water.

[0048] The styrene-maleic anhydride copolymer sodium salt solution has solid content of 40±1%, and the weight ratio of styrene to maleic anhydride in the styrene-maleic anhydride copolymer sodium salt solution is 1:1.

[0049] The application further provides a preparation method of the water-based acrylic exterior wall emulsion, and the water-based acrylic exterior wall emulsion is the aforementioned water-based acrylic exterior wall emulsion, and the preparation method comprises the following steps.

[0050] S001. 40 parts of deionized water and 0.5 parts of sodium dodecyl alcohol polyoxyethylene ether sulfate are added into a reaction kettle, and a bottom liquid is prepared by stirring;

[0051] S002. 30 parts of deionized water and 1.3 parts of sodium dodecyl alcohol polyoxyethylene ether sulfate are added into an emulsifying cylinder, stirred uniformly, and then 58 parts of methyl methacrylate, 30 parts of butyl acrylate, 2 parts of acrylic acid, 3 parts of methacrylamide and 1 part of itaconic acid are sequentially added, stirred and mixed uniformly to prepare a pre-emulsion;

[0052] S003. 30 parts of deionized water and 0.5 parts of ammonium persulfate are stirred and mixed to prepare an initiator solution;

[0053] S004. The temperature in the reaction kettle is raised to 80 DEG C, 4% of the total amount of the pre-emulsion and 10% of the total amount of the initiator solution are added into the bottom liquid, and a seed emulsion is prepared after 20 min of heat preservation, and the remaining pre-emulsion and initiator solution are added dropwise into the reaction kettle at a uniform speed for 150 min;

[0054] Step S005. After step S004, the temperature in the reactor is maintained at 80℃ ～ 82℃, and the temperature is maintained for 50 min. After the temperature is maintained, the temperature in the reactor is reduced to room temperature, and the pH of the liquid in the reactor is adjusted to 7.0 by using a sodium hydroxide solution ～ 9.0, and then 1 part of a styrene-maleic anhydride copolymer sodium salt solution is added, and the liquid in the reactor is stirred for 20 min. After the stirring is completed, the liquid in the reactor is filtered to obtain an aqueous acrylic exterior wall emulsion.

[0055] Further, in step S004, the remaining initiator solution is added 10 min later than the remaining pre-emulsion.

[0056] Example 2

[0057] The present application provides an aqueous acrylic exterior wall emulsion, which comprises the following components by weight: 55 parts of methyl methacrylate, 33 parts of butyl acrylate, 3 parts of acrylic acid, 3.5 parts of a styrene-maleic anhydride copolymer sodium salt solution, 1 part of methyl methacrylamide, 2 parts of itaconic acid, 1.8 parts of sodium alpha-allyl sulfonate, 1 part of potassium persulfate, and 100 parts of deionized water.

[0058] The styrene-maleic anhydride copolymer sodium salt solution has a solid content of 40±1%, and the weight ratio of styrene to maleic anhydride in the styrene-maleic anhydride copolymer sodium salt solution is 1:1.

[0059] The present application also provides a preparation method of an aqueous acrylic exterior wall emulsion, wherein the aqueous acrylic exterior wall emulsion is the aforementioned aqueous acrylic exterior wall emulsion, and the preparation method comprises the following steps:

[0060] Step S001. 40 parts of deionized water and 0.6 parts of sodium alpha-allyl sulfonate are added to a reactor to prepare a bottom liquid.

[0061] Step S002. 30 parts of deionized water and 1.2 parts of sodium alpha-allyl sulfonate are added to an emulsifying cylinder, and then 55 parts of methyl methacrylate, 33 parts of butyl acrylate, 3 parts of acrylic acid, 1 part of methyl methacrylamide, and 2 parts of itaconic acid are sequentially added to the emulsifying cylinder, and the mixture is stirred to prepare a pre-emulsion.

[0062] Step S003. 30 parts of deionized water and 1 part of potassium persulfate are stirred and mixed to prepare an initiator solution.

[0063] Step S004. The temperature in the reaction kettle is raised to 84℃, and 5% of the total amount of pre-emulsion and 20% of the total amount of initiator solution are added to the bottom liquid. After 25 minutes of incubation, the seed emulsion is prepared, and the remaining pre-emulsion and initiator solution are added to the reaction kettle at a uniform speed for 180 minutes.

[0064] Step S005. After step S004 is completed, the temperature in the reaction kettle is maintained at 84℃ ～ 86℃, and incubated for 60 minutes. After the incubation is completed, the temperature in the reaction kettle is reduced to room temperature, and the pH of the liquid in the reaction kettle is adjusted to 7.0 with sodium hydroxide solution ～ 9.0, and then 3.5 parts of a styrene-maleic anhydride copolymer sodium salt solution is added, and the liquid in the reaction kettle is stirred for 20 minutes. After the stirring is completed, the liquid in the reaction kettle is filtered to obtain the water-based acrylic exterior wall emulsion.

[0065] Further, in step S004, the remaining initiator solution is added 10 minutes later than the remaining pre-emulsion.

[0066] Example 3

[0067] The present application provides a water-based acrylic exterior wall emulsion, which comprises the following components by weight: 51.5 parts of methyl methacrylate, 36.5 parts of butyl acrylate, 4 parts of acrylic acid, 6 parts of a styrene-maleic anhydride copolymer sodium salt solution, 2 parts of methyl methacrylamide, 3 parts of itaconic acid, 1.8 parts of sodium dodecyl diphenyl ether disulfonate, 1.5 parts of sodium persulfate, and 100 parts of deionized water.

[0068] The styrene-maleic anhydride copolymer sodium salt solution has a solid content of 40±1%, and the weight ratio of styrene to maleic anhydride in the styrene-maleic anhydride copolymer sodium salt solution is 1:1.

[0069] The present application also provides a preparation method of a water-based acrylic exterior wall emulsion, wherein the water-based acrylic exterior wall emulsion is the aforementioned water-based acrylic exterior wall emulsion, and the preparation method comprises the following steps:

[0070] Step S001. 40 parts of deionized water and 0.7 parts of sodium dodecyl diphenyl ether disulfonate are added to a reaction kettle to prepare a bottom liquid.

[0071] Step S002. 30 parts of deionized water and 1.1 parts of sodium dodecyl diphenyl ether disulfonate are added to an emulsifying cylinder, and then 51.5 parts of methyl methacrylate, 36.5 parts of butyl acrylate, 4 parts of acrylic acid, 2 parts of methyl methacrylamide, and 3 parts of itaconic acid are sequentially added, and stirred to obtain a pre-emulsion.

[0072] Step S003. Stir and mix 30 parts of deionized water with 1.5 parts of sodium persulfate to prepare an initiator solution;

[0073] Step S004. The temperature in the reaction kettle is raised to 86℃, and 8% of the total amount of pre-emulsion and 30% of the total amount of initiator solution are added to the bottom liquid. After 30 min of incubation, a seed emulsion is prepared, and the remaining pre-emulsion and initiator solution are added to the reaction kettle at a uniform speed for 210 min.

[0074] Step S005. After step S004 is completed, the temperature in the reaction kettle is maintained at 86℃ ～ 88℃, and incubated for 70 min. After the incubation is completed, the temperature in the reaction kettle is reduced to room temperature, and the pH of the liquid in the reaction kettle is adjusted to 7.0 ～ 9.0 with 6 parts of a styrene-maleic anhydride copolymer sodium salt solution, and the liquid in the reaction kettle is stirred for 40 min. After the stirring is completed, the liquid in the reaction kettle is filtered to obtain a water-based acrylic exterior wall emulsion.

[0075] Further, in step S004, the remaining initiator solution is added 10 min later than the remaining pre-emulsion.

[0076] Example 4

[0077] The present application provides a water-based acrylic exterior wall emulsion, which comprises the following components by weight: 53 parts of methyl methacrylate, 37 parts of butyl acrylate, 5 parts of acrylic acid, 5 parts of a styrene-maleic anhydride copolymer sodium salt solution, 2 parts of methacrylamide, 3 parts of itaconic acid, 1.7 parts of sodium dodecyl alcohol polyoxyethylene ether sulfate, 1.5 parts of ammonium persulfate, and 100 parts of deionized water.

[0078] The styrene-maleic anhydride copolymer sodium salt solution has a solid content of 40±1%, and the weight ratio of styrene to maleic anhydride in the styrene-maleic anhydride copolymer sodium salt solution is 1:1.

[0079] The present application also provides a preparation method of a water-based acrylic exterior wall emulsion, wherein the water-based acrylic exterior wall emulsion is the aforementioned water-based acrylic exterior wall emulsion, and the method comprises the following steps:

[0080] Step S001. Add 40 parts of deionized water and 0.7 parts of sodium dodecyl alcohol polyoxyethylene ether sulfate to a reaction kettle to prepare a bottom liquid.

[0081] Step S002. 30 parts of deionized water and 1.0 parts of sodium dodecyl alcohol polyoxyethylene ether sulfate were added to the emulsification cylinder, stirred uniformly, and then 53 parts of methyl methacrylate, 37 parts of butyl acrylate, 5 parts of acrylic acid, 2 parts of methacrylamide and 3 parts of itaconic acid were sequentially added, stirred and mixed uniformly to prepare a pre-emulsion;

[0082] Step S003. 30 parts of deionized water was stirred and mixed with 1.5 parts of ammonium persulfate to prepare an initiator solution;

[0083] Step S004. The temperature in the reaction kettle was raised to 86℃, and 8% of the total amount of the pre-emulsion and 30% of the total amount of the initiator solution were added to the bottom liquid, and after 30min of incubation, a seed emulsion was prepared, and the remaining pre-emulsion and initiator solution were added to the reaction kettle at a uniform speed, and the dropwise adding time was 240min;

[0084] Step S005. After step S004 was completed, the temperature in the reaction kettle was kept at 86℃ ～ 88℃, and incubated for 70min, then the temperature in the reaction kettle was reduced to room temperature, and the pH of the liquid in the reaction kettle was adjusted to 7.0 ～ 9.0 with sodium hydroxide solution, and then 5 parts of styrene-maleic anhydride copolymer sodium salt solution was added, and the liquid in the reaction kettle was stirred for 30min; After stirring, the liquid in the reaction kettle was filtered to obtain a water-based acrylic exterior wall emulsion.

[0085] Further, in step S004, the remaining initiator solution is added 10min later than the remaining pre-emulsion.

[0086] Comparative Example 1

[0087] The difference between Comparative Example 1 and Example 1 is that no styrene-maleic anhydride copolymer sodium salt solution is used in Comparative Example 1.

[0088] Comparative Example 2

[0089] The present application provides a water-based acrylic exterior wall emulsion, which comprises the following components by weight: 61.5 parts of methyl methacrylate, 26.5 parts of isooctyl acrylate, 2 parts of acrylic acid, 6 parts of styrene-maleic anhydride copolymer sodium salt solution, 3 parts of methacrylamide, 1 part of itaconic acid, 1.8 parts of sodium dodecyl alcohol polyoxyethylene ether sulfate, 0.5 parts of ammonium persulfate, and 100 parts of deionized water;

[0090] The solid content of the styrene-maleic anhydride copolymer sodium salt solution is 40±1%, and the weight ratio of styrene to maleic anhydride in the styrene-maleic anhydride copolymer sodium salt solution is 1:1.

[0091] The application further provides a preparation method of the water-based acrylic exterior wall emulsion.

[0092] Step S001. 40 parts of deionized water and 0.5 parts of sodium dodecyl alcohol polyoxyethylene ether sulfate are added into a reaction kettle and stirred to prepare a bottom solution;

[0093] Step S002. 30 parts of deionized water and 1.3 parts of sodium dodecyl alcohol polyoxyethylene ether sulfate are added into an emulsifying cylinder and stirred uniformly, and then 61.5 parts of methyl methacrylate, 26.5 parts of isooctyl acrylate, 2 parts of acrylic acid, 3 parts of methacrylamide and 1 part of itaconic acid are sequentially added and stirred and mixed uniformly to prepare a pre-emulsion;

[0094] Step S003. 30 parts of deionized water and 0.5 parts of an initiator are stirred and mixed to prepare an initiator solution;

[0095] Step S004. The temperature in the reaction kettle is increased to 80℃, and 4% of the total amount of the pre-emulsion and 10% of the total amount of the initiator solution are added into the bottom solution, and a seed emulsion is prepared after 20 min of heat preservation, and the remaining pre-emulsion and initiator solution are added dropwise into the reaction kettle at a uniform speed and for 150 min;

[0096] Step S005. After the end of step S004, the temperature in the reaction kettle is kept at 80℃ ～ 82℃, and the temperature in the reaction kettle is reduced to room temperature, and then the pH of the liquid in the reaction kettle is adjusted to 7.0 ～ 9.0, and then 6 parts of a styrene-maleic anhydride copolymer sodium salt solution is added, and the liquid in the reaction kettle is stirred for 20 min; after the stirring is completed, the liquid in the reaction kettle is filtered to obtain the water-based acrylic exterior wall emulsion.

[0097] Further, in step S004, the remaining initiator solution is added dropwise 10 min later than the remaining pre-emulsion.

[0098] Comparative Example 3

[0099] The application provides a water-based acrylic exterior wall emulsion, which comprises the following components in parts by weight: 58 parts of methyl methacrylate, 30 parts of butyl acrylate, 1 part of acrylic acid, 6 parts of a styrene-maleic anhydride copolymer sodium salt solution, 1 part of itaconic acid, 1.8 parts of sodium dodecyl alcohol polyoxyethylene ether sulfate, 0.5 parts of ammonium persulfate and 100 parts of deionized water.

[0100] The solid content of the styrene-maleic anhydride copolymer sodium salt solution is 40±1%, and the weight ratio of styrene to maleic anhydride in the styrene-maleic anhydride copolymer sodium salt solution is 1:1.

[0101] The application further provides a preparation method of the water-based acrylic exterior wall emulsion.

[0102] Step S001. 40 parts of deionized water and 0.5 parts of sodium dodecyl alcohol polyoxyethylene ether sulfate are added to a reaction kettle to prepare a bottom solution by stirring;

[0103] Step S002. 30 parts of deionized water and 1.3 parts of sodium dodecyl alcohol polyoxyethylene ether sulfate are added to an emulsifying cylinder, and after stirring uniformly, 58 parts of methyl methacrylate, 30 parts of butyl acrylate, 1 part of acrylic acid and 1 part of itaconic acid are sequentially added, and after stirring and mixing uniformly, a pre-emulsion is prepared;

[0104] Step S003. 30 parts of deionized water are stirred and mixed with 0.5 parts of an initiator to prepare an initiator solution;

[0105] Step S004. The temperature in the reaction kettle is raised to 80℃, and 4% of the total amount of the pre-emulsion and 10% of the total amount of the initiator solution are added to the bottom solution, and after being kept at 80℃ for 20 minutes, a seed emulsion is prepared, and the remaining pre-emulsion and initiator solution are added dropwise into the reaction kettle at a uniform speed, and the dropwise adding time is 150 minutes;

[0106] Step S005. After step S004 is completed, the temperature in the reaction kettle is kept at 80℃ ～ 82℃, and the temperature in the reaction kettle is kept at 80℃ for 50 minutes, and after the keeping is completed, the temperature in the reaction kettle is reduced to room temperature, and then the pH of the liquid in the reaction kettle is adjusted to 7.0 ～ 9.0, and then 6 parts of a styrene-maleic anhydride copolymer sodium salt solution is added, and the liquid in the reaction kettle is stirred for 20 minutes; after the stirring is completed, the liquid in the reaction kettle is filtered to obtain the water-based acrylic exterior wall emulsion.

[0107] Further, in step S004, the remaining initiator solution is added dropwise 10 minutes later than the remaining pre-emulsion.

[0108] The water-based acrylic exterior wall emulsion prepared by examples 1 to 4 and comparative examples 1 to 3 is used to prepare an exterior wall emulsion paint. The exterior wall emulsion paint comprises the following components by weight:

[0109] Water-based acrylic exterior wall emulsion 70 parts, polyvinyl chloride 15 parts, pigment and filler 30 parts, thickening agent 5 parts, defoaming agent 2 parts, leveling agent 0.2 parts, mildewcide 0.5 parts, antioxidant 1 part, dispersant 0.8 parts, surfactant 0.4 parts, deionized water 60 parts.

[0110] The above prepared exterior wall emulsion paint was made into a plate according to the content specified in GB / T 9755-2014 "Synthetic resin emulsion exterior wall paint" standard, and the stain resistance and washability of the emulsion paint were tested, and the test results are shown in the following table:

[0111]

[0112]

[0113] In the above table, MMA is methyl methacrylate, BA is butyl acrylate, EHA is isooctyl acrylate, AA is acrylic acid, MAM is methacrylamide, ITA is itaconic acid, and SMA is styrene-maleic anhydride copolymer sodium salt solution. In addition, in the stain resistance index, the smaller the value, the better the stain resistance of the paint film, and when the stain resistance is ≤15, it is a superior product.

[0114] From the test results in the above table, it can be seen that: (1) the exterior wall emulsion paint containing the water-based acrylic exterior wall emulsion prepared in Examples 1 to 4 has a paint film with a stain resistance that meets the requirements of a superior product;

[0115] (2) The water-based acrylic exterior wall emulsion prepared in Comparative Example 1 does not contain styrene-maleic anhydride copolymer sodium salt solution, although it is used in exterior wall emulsion paint, the paint film has a stain resistance that meets the requirements of a superior product, but it is not as good as the exterior wall emulsion paint containing the water-based acrylic exterior wall emulsion prepared in Examples 1 to 4;

[0116] (3) Comparative Document 2 uses isooctyl acrylate with strong hydrophobicity, even if 6 parts of styrene-maleic anhydride copolymer sodium salt solution is added, the stain resistance of the paint film of the final exterior wall emulsion paint cannot meet the requirements of a superior product;

[0117] (4) Comparative Example 4 has an unreasonable arrangement of hydrophilic functional monomers, even if 6 parts of styrene-maleic anhydride copolymer sodium salt solution is added, the stain resistance of the paint film of the final exterior wall emulsion paint cannot meet the requirements of a superior product.

[0118] In summary, the present application provides a kind of water-based acrylic outer wall emulsion and its preparation method, by using more hydrophilic hard monomer methyl methacrylate and soft monomer butyl acrylate, water-based acrylic outer wall emulsion has good film-forming property, while also can improve the hydrophilicity and hardness of paint film;By using the acrylic acid, methacrylamide and itaconic acid with hydrophilic group, the hydrophilicity of paint film can be further improved;In addition, by introducing styrene-maleic anhydride copolymer salt solution, a special hydrophilic material, not only can improve the hardness of paint film, but also can improve the hydrophilicity of paint film.The water-based acrylic outer wall emulsion provided by the present application has improved hydrophilicity after film-forming, so the paint containing the water-based acrylic outer wall emulsion can not only improve the stain resistance of paint film by improving the hardness of paint film, but also can significantly improve the stain resistance of paint film by improving the hydrophilicity of paint film.

[0119] It can be understood that, for those skilled in the art, equivalent replacements or changes can be made according to the technical solutions and inventive concepts of the present application, and all such changes or replacements shall fall within the protection scope of the claims appended to the present application.

Claims

1. An aqueous acrylic exterior wall emulsion, characterized by, The composition comprises the following components by weight: 80-100 parts of methyl methacrylate and butyl acrylate, 2-5 parts of acrylic acid, 1-6 parts of styrene-maleic anhydride copolymer salt solution, 1-3 parts of methacrylamide, 1-3 parts of itaconic acid, 1.5-2 parts of emulsifier, 0.5-2 parts of initiator, and 100 parts of deionized water; The solid content of the styrene-maleic anhydride copolymer salt solution is 40±1%; The styrene-maleic anhydride copolymer salt solution is a styrene-maleic anhydride copolymer sodium salt solution; the styrene-maleic anhydride copolymer sodium salt solution provides hydrophilicity for the paint film; The methyl methacrylate accounts for 55-67% of the total weight of the methyl methacrylate and butyl acrylate; The emulsifier is one of polyoxyethylene-polyoxypropylene block copolymer, octadecyl alcohol polyoxyethylene ether, sodium dodecyl alcohol polyoxyethylene ether sulfate, sodium α-allyl sulfonate, and sodium dodecyl diphenyl ether disulfate.

2. The aqueous acrylic exterior wall emulsion according to claim 1, characterized in that, In the styrene-maleic anhydride copolymer sodium salt solution, the weight ratio of styrene to maleic anhydride is 1:

1.

3. The aqueous acrylic exterior wall emulsion according to claim 1, characterized in that, The initiator includes at least one of ammonium persulfate, potassium persulfate, and sodium persulfate.

4. The aqueous acrylic exterior wall emulsion of claim 1, wherein, The pH is 7.0-9.

0.

5. A process for the preparation of an aqueous acrylic exterior wall emulsion as claimed in any one of claims 1 to 4, characterized in that, The method comprises the following steps: Step S001. 40 parts of deionized water and 0.5-0.7 parts of emulsifier are added to a reaction kettle and stirred to prepare a base solution; Step S002. 30 parts of deionized water and 1-1.3 parts of emulsifier are added to an emulsifying cylinder, stirred uniformly, and then 50-60 parts of methyl methacrylate, 30-40 parts of butyl acrylate, 2-5 parts of acrylic acid, 1-3 parts of methacrylamide, and 1-3 parts of itaconic acid are sequentially added, stirred and mixed uniformly to prepare a pre-emulsion; Step S003. 30 parts of deionized water is stirred and mixed with 0.5-2 parts of initiator to prepare an initiator solution; Step S004. The temperature in the reaction kettle is raised to 80-88℃, and 4-8% of the total amount of the pre-emulsion and 10-30% of the total amount of the initiator solution are added to the base solution, and the temperature is maintained for 20-30 minutes to prepare a seed emulsion, while the remaining pre-emulsion and initiator solution are added dropwise to the reaction kettle at a uniform speed for 150-240 minutes; Step S005. After step S004 is completed, the temperature in the reaction kettle is maintained at 80-88℃ for 50-70 minutes, and then the temperature in the reaction kettle is reduced to room temperature, and the pH of the liquid in the reaction kettle is adjusted with sodium hydroxide solution, and then 1-6 parts of styrene-maleic anhydride copolymer salt solution is added, and the liquid in the reaction kettle is stirred for 20-40 minutes; after stirring, the liquid in the reaction kettle is filtered to obtain a water-based acrylic acid exterior wall emulsion.

6. The method of preparing an aqueous acrylic exterior wall emulsion according to claim 5, characterized by, In step S004, the remaining initiator solution is added 10 minutes later than the remaining pre-emulsion.

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