Nano-cellulose modified acrylic acid water-based emulsion as well as preparation method and application thereof

Abstract

The invention discloses a nanocellulose modified acrylic acid water-based emulsion as well as a preparation method and application thereof, and relates to the technical field of polymer composite materials. The invention relates to a modified acrylic aqueous emulsion, which comprises 180-220 parts of an acrylate monomer, 45-60 parts of a functional monomer, 3-5 parts of a nano cellulose solution, 4-6 parts of an emulsifier, 1.5-2 parts of an initiator, 2-3 parts of sodium bicarbonate and 275-300 parts of deionized water, and the functional monomer comprises hydroxyl acrylate, acrylonitrile and fluorine-containing acrylate. According to the present invention, the fluorine-containing acrylate is matched with the nano cellulose to modify the acrylic emulsion so as to prepare the aqueous emulsion with good film-forming property, the formed coating has good adhesion, good stain resistance, good hot oil resistance and good mechanical strength, and if the aqueous emulsion is applied to the surface modification of the filter material, the hand feeling of the filter material can be improved, and the filtration effect can be improved; the stain resistance and the service life of the surface of the filter material can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer composites, and in particular to a nano-cellulose modified acrylic aqueous emulsion, a preparation method thereof, and an application thereof. Background Art

[0002] Filters play a crucial role in modern industry and daily life and are widely used in many fields such as air purification, water treatment, and food processing. Since most of the filter media of traditional filters are made of materials such as fiber composites or non-woven fabrics, their stain resistance is poor and they are easily polluted by the external environment, resulting in a low service life. Therefore, there are still many limitations in the use process.

[0003] In order to improve the performance of the filter media, in the prior art, an aqueous emulsion is often used to impregnate and modify the surface of the filter media. The aqueous emulsion used for the surface modification of the filter media generally has good film-forming properties and water resistance, and can form a protective layer on the surface of the filter media. It can not only improve the physical strength (such as stiffness and bursting strength) and structural strength of the filter media to a certain extent, but also endow the filter media with a certain surface anti-fouling ability.

[0004] However, most of the traditional aqueous emulsions for the surface modification of filter media are still prepared using thermosetting phenolic resins, and there are still deficiencies in terms of durability and environmental protection. For example, the impregnated filter media lacks flexibility, is brittle as a whole, and is prone to falling off, breaking, or aging. At the same time, a large amount of solvents that are not easily recycled are consumed during production and preparation, which will cause pollution to the environment. Therefore, developing an environmentally friendly aqueous emulsion with good durability is of great significance for promoting the development of the filter media industry. Summary of the Invention

[0005] In order to improve the durability and environmental protection of the coating formed by the aqueous emulsion for the surface modification of filter media, and thus improve the stain resistance and service life of the impregnated filter media, the present application provides a nano-cellulose modified acrylic aqueous emulsion, a preparation method thereof, and an application thereof.

[0006] In a first aspect, a modified acrylic aqueous emulsion provided by the present application adopts the following technical solution: A modified acrylic aqueous emulsion, comprising the following raw materials in parts by weight: Acrylate monomer: 180 - 220 parts; Functional monomer: 45 - 60 parts; Nano-cellulose liquid: 3 - 5 parts; Emulsifier: 4 - 6 parts; Initiator: 1.5 - 2 parts; Sodium bicarbonate: 2 - 3 parts; Deionized water: 275 - 300 parts; Among them, the acrylate monomer is a mixture of ethyl acrylate and butyl acrylate in a mass ratio of (2.6 - 5):1, and the functional monomer is a mixture of hydroxyacrylate, acrylonitrile, and fluorinated acrylate in a mass ratio of (4 - 10):(1 - 2):1.

[0007] By adopting the above technical solution, an aqueous emulsion with good film-forming properties can be prepared. Moreover, the coating formed by the aqueous emulsion has good adhesion, stain resistance, heat and oil resistance, and mechanical strength. If this aqueous emulsion is applied to the surface modification of filter materials, it can not only improve the overall flexibility of the filter materials, improve the hand feeling of the filter materials, but also improve the stain resistance and service life of the filter material surface, and reduce the occurrence of phenomena such as peeling, cracking, or aging of the surface modification coating of the filter material. In addition, deionized water is used as the main solvent in the above raw materials, which does not require a large amount of solvents that are not easily recovered in production preparation, and will not cause environmental pollution. It is not only easy to process, but also meets the environmental protection requirements, and has broad application prospects and market value.

[0008] Optionally, the fluorinated acrylate is one of hexafluorobutyl acrylate, hexafluorobutyl methacrylate, dodecafluoroheptyl acrylate, or dodecafluoroheptyl methacrylate.

[0009] By adopting the above technical solution, different fluorinated acrylates can be used to adjust the physical and chemical properties of the aqueous emulsion, so that the formed coating can meet the requirements of filter materials of different materials. At the same time, by introducing fluorine atoms into the aqueous emulsion through the above several fluorinated acrylates, an environmentally friendly aqueous emulsion with better performance than the existing emulsion can be prepared without consuming a large amount of solvents that are not easily recovered, which meets the requirements of current industrial development.

[0010] Optionally, the nano-cellulose liquid is prepared by mixing nano-cellulose with deionized water, and the solid content of the nano-cellulose liquid is 2% - 5%.

[0011] By adopting the above technical solution, the addition amount of nano-cellulose can be controlled within a reasonable range, which is not only beneficial to the modification of acrylic aqueous emulsion in cooperation with fluorinated acrylate, so that the coating formed by the aqueous emulsion has better comprehensive performance, but also beneficial to preventing the viscosity of the aqueous emulsion from being too high during mixing or the coating being too hard and brittle after formation due to excessive addition of nano-cellulose.

[0012] Optionally, the fluorinated acrylate is specifically hexafluorobutyl acrylate, and the mass ratio of hexafluorobutyl acrylate to the solid effective substance in the nano-cellulose liquid is (20 - 75):1.

[0013] By adopting the above technical scheme, a modified acrylic water-based emulsion with good comprehensive performance can be prepared. Although the prepared water-based emulsion is still lacking in performance compared to the water-based emulsion prepared by using dodecafluoroheptyl acrylate, the comprehensive raw material cost is lower, the cost performance is higher, and it has a higher market value. In addition, the preparation of hexafluorobutyl acrylate is more environmentally friendly and safer than dodecafluoroheptyl acrylate, conforms to green technology, and has certain environmental protection.

[0014] Optionally, the nanocellulose is specifically selected from carboxylated nanocellulose.

[0015] By adopting the above technical solution, the carboxyl groups on the surface of carboxylated nanocellulose can provide more reaction sites, so that nanocellulose can fully react and connect with other molecules, which is beneficial to improve the monomer conversion rate of the aqueous emulsion, and further improve the emulsification performance and film-forming property of the aqueous emulsion. In addition, the aqueous emulsion prepared by modifying the acrylic aqueous emulsion with carboxylated nanocellulose and hexafluorobutyl acrylate has similar comprehensive performance to the aqueous emulsion modified with dodecafluoroheptyl acrylate, but the raw material cost is greatly reduced, which is beneficial to improve the cost performance of the aqueous emulsion, so that it has a wide range of application prospects and market value.

[0016] Optionally, the emulsifier is an alkylphenol polyoxyethylene ether emulsifier, and the initiator is one of potassium persulfate or ammonium persulfate.

[0017] In the second aspect, the present application provides a method for preparing a modified acrylic acid aqueous emulsion using the following technical solution: A method for preparing a modified acrylic acid aqueous emulsion comprises the following steps: S1. Take 20% of emulsifier and 55% of deionized water, stir and mix them thoroughly to obtain a base liquid; take acrylate monomer, functional monomer, 80% of emulsifier and nanocellulose liquid, stir and mix them thoroughly to obtain a pre-emulsified monomer liquid; take initiator, sodium bicarbonate and 40% of deionized water, stir and mix them thoroughly to obtain an initiator liquid; S2, stirring and heating the base liquid to 83-85°C, then quickly adding 10% of the initiator liquid, stirring continuously for 3-5 minutes, and then simultaneously dripping the pre-emulsified monomer liquid and the remaining initiator liquid, stirring continuously and controlling the dripping temperature to maintain at 80-82°C, wherein the dripping of the pre-emulsified monomer liquid must be completed within 4 hours, and ensure that the dripping of the initiator liquid is completed 15-20 minutes later than the pre-emulsified monomer liquid; S3, after the dropwise addition is completed, the temperature is further heated to 86-88°C within 30 minutes, and the temperature is kept for reaction for another 1-2 hours to obtain an emulsion matrix; S4. After taking a sample from the emulsion matrix and smelling it until there is no obvious irritating odor, the sample is cooled to below 40° C. and filtered to obtain a modified acrylic acid aqueous emulsion.

[0018] By adopting the above technical solution, the preparation method is simple, and a large amount of solvents that are not easily recycled are not consumed during production, which has a certain environmental friendliness.

[0019] Optionally, in step S4, when the emulsion matrix is cooled to 50-55°C, a tackifier can be added to the emulsion matrix. The steps for adding the tackifier are as follows: After sampling and smelling the emulsion matrix until there is no obvious pungent smell, when it is cooled to 50-52°C, add the tackifier, maintain the temperature and continuously stir and mix evenly, and then cool it below 40°C and filter to obtain a modified acrylic aqueous emulsion.

[0020] Optionally, the tackifier is prepared by dissolving a tackifying resin in 2 times the mass of xylene. The addition amount of the tackifying resin is 5%-8% of the sum of the added masses of the acrylate monomer and the functional monomer, and the tackifying resin is one of terpene resin or rosin.

[0021] By adopting the above technical solution, using one of terpene resin or rosin as a tackifier and adding it to the aqueous emulsion can not only effectively improve the initial tack of the aqueous emulsion, which is beneficial to improving the adhesion of the coating, but also beneficial to improving the mechanical strength and heat and oil resistance of the coating, and extending the service life of the coating.

[0022] In the third aspect, the application of a modified acrylic aqueous emulsion provided by this application adopts the following technical solution: An application of a modified acrylic aqueous emulsion is used for surface impregnation treatment of paper filter materials or fiber filter materials.

[0023] By adopting the above technical solution, it is beneficial to improve the softness, stain resistance and service life of the impregnated paper filter material or fiber filter material.

[0024] In summary, the technical solution of this application has at least any one of the following beneficial effects: 1. By using a small amount of fluorinated acrylate as a functional monomer and cooperating with nanocellulose to modify the acrylic aqueous emulsion, an aqueous emulsion with good film-forming performance can be prepared, and the coating formed by the aqueous emulsion has good adhesion, stain resistance, heat and oil resistance and mechanical strength.

[0025] 2. By selecting carboxylated nanocellulose and mixing it with hexafluorobutyl acrylate in a certain mass ratio to modify the acrylic aqueous emulsion, an aqueous emulsion with excellent comprehensive performance and low cost can be prepared, and it has broad application prospects and market value.

[0026] 3. By applying the prepared modified acrylic aqueous emulsion to the impregnation treatment of paper filter materials or fiber filter materials, it is beneficial to improve the stain resistance and service life of the impregnated filter materials. Detailed implementation mode

[0027] The present application will be further described in detail below in conjunction with preparation examples, examples and comparative examples.

[0028] Preparation example

Preparation example 1

[0029]

Preparation example 2

[0030]

Preparation example 3

[0031]

Example 1

[0032] Among them, the acrylate monomer includes 150 g of ethyl acrylate and 50 g of butyl acrylate; the functional monomer includes 30 g of 2-hydroxyethyl acrylate, 10 g of acrylonitrile, and 5 g of fluorinated acrylate. In this example, the fluorinated acrylate is specifically 2,2,3,3,4,4-hexafluorobutyl acrylate; the nano-cellulose solution is specifically the nano-cellulose solution prepared in

Preparation example 1

[0033] A preparation method of a modified acrylic aqueous emulsion includes the following steps: S1. Take 1 g of emulsifier OP-701 and 150 g of deionized water and fully stir and mix them to obtain a bottom liquid; take the acrylate monomer, functional monomer, the remaining emulsifier and nano-cellulose solution and fully stir and mix them to obtain a pre-emulsified monomer liquid; take potassium persulfate, sodium bicarbonate and the remaining deionized water and fully stir and mix them to obtain an initiator liquid; S2. Stir and heat the bottoming liquid to 83 - 85 °C, then quickly add 10% of the initiator solution. After continuously stirring for 5 min, start to simultaneously drip-feed the pre-emulsified monomer solution and the remaining initiator solution, continuously stir and control the dripping temperature to be maintained at 80 - 82 °C. Among them, the dripping of the pre-emulsified monomer solution needs to be completed within 4 h, and it is ensured that the initiator solution finishes dripping 15 min later than the pre-emulsified monomer solution; S3. After the dripping is completed, further heat the temperature to 86 °C within 30 min and keep it warm for reaction for 1 h to obtain the emulsion matrix; S4. After sampling from the emulsion matrix and smelling until there is no obvious pungent smell, cool it down to below 40 °C and filter it through a nylon cloth for discharging to obtain a modified acrylic aqueous emulsion.

[0034] The application of a modified acrylic aqueous emulsion can be used for impregnating the surface of paper filter materials or fiber filter materials. In this embodiment, it can be specifically applied to impregnating the surface of PET non-woven filter cloth.

[0035]

Example 2

[0036] Among them, the acrylate monomer comprises 130 g of ethyl acrylate and 50 g of butyl acrylate; the functional monomer comprises 40 g of 2-hydroxyethyl acrylate, 10 g of acrylonitrile, and 5 g of fluorinated acrylate. In this embodiment, the fluorinated acrylate is specifically hexafluorobutyl methacrylate; the nano-cellulose solution is specifically the nano-cellulose solution prepared in

Preparation Example 2

[0037] A preparation method of a modified acrylic aqueous emulsion comprises the following steps: S1. Take 1 g of emulsifier OP-701 and 150 g of deionized water and stir and mix them fully to obtain the bottoming liquid; take the acrylate monomer, functional monomer, the remaining emulsifier, and the nano-cellulose solution and stir and mix them fully to obtain the pre-emulsified monomer solution; take potassium persulfate, sodium bicarbonate, and the remaining deionized water and stir and mix them fully to obtain the initiator solution; S2. Stir and heat the bottoming liquid to 83 - 85 °C, then quickly add 10% of the initiator solution. After continuously stirring for 5 min, start to simultaneously drip-feed the pre-emulsified monomer solution and the remaining initiator solution, continuously stir and control the dripping temperature to be maintained at 80 - 82 °C. Among them, the dripping of the pre-emulsified monomer solution needs to be completed within 4 h, and it is ensured that the initiator solution finishes dripping 15 min later than the pre-emulsified monomer solution; S3. After the dropping is completed, further heat the temperature to 88 °C within 30 min, and keep it warm for reaction for another 2 h to obtain an emulsion matrix; S4. After sampling from the emulsion matrix to smell until there is no obvious pungent smell, cool it down to below 40 °C and filter it through a nylon cloth for discharging to obtain a modified acrylic aqueous emulsion.

[0038] The application of a modified acrylic aqueous emulsion can be used for impregnating the surface of a paper filter material or a fiber filter material. In this embodiment, it can be specifically applied to impregnating the surface of a PE non-woven filter cloth.

[0039]

Example 3

[0040] Among them, the acrylate monomer comprises 180 g of ethyl acrylate and 40 g of butyl acrylate; the functional monomer comprises 50 g of 2-hydroxyethyl acrylate, 5 g of acrylonitrile, and 5 g of fluorinated acrylate. In this embodiment, the fluorinated acrylate is specifically dodecafluoroheptyl acrylate; the nano-cellulose solution is specifically the nano-cellulose solution prepared in

Preparation Example 1

[0041] A preparation method of a modified acrylic aqueous emulsion comprises the following steps: S1. Take 1 g of emulsifier OP-701 and 150 g of deionized water and stir and mix them fully to obtain a bottom liquid; take the acrylate monomer, functional monomer, the remaining emulsifier, and the nano-cellulose solution and stir and mix them fully to obtain a pre-emulsified monomer liquid; take potassium persulfate, sodium bicarbonate, and the remaining deionized water and stir and mix them fully to obtain an initiator liquid; S2. Stir and heat the bottom liquid to 83-85 °C, then quickly add 10% of the initiator liquid. After continuously stirring for 5 min, start to simultaneously dropwise add the pre-emulsified monomer liquid and the remaining initiator liquid, continuously stir and control the dropping temperature to be maintained at 80-82 °C, wherein the dropping of the pre-emulsified monomer liquid needs to be completed within 4 h, and it is ensured that the initiator liquid is completed 20 min later than the pre-emulsified monomer liquid; S3. After the dropping is completed, further heat the temperature to 88 °C within 30 min, and keep it warm for reaction for 1 h to obtain an emulsion matrix; S4. After sampling from the emulsion matrix to smell until there is no obvious pungent smell, when the temperature is cooled down to 50 °C, add a tackifier to the emulsion matrix, and keep stirring and mixing at a constant temperature for 5 min, then cool it down to below 40 °C again and filter it through a nylon cloth for discharging to obtain a modified acrylic aqueous emulsion.

[0042] Among them, the tackifier added in step S4 is prepared by dissolving terpene resin in 2 parts by mass of xylene, and the addition amount of terpene resin is 5% of the sum of the addition masses of acrylate monomers and functional monomers, that is, 14 g.

[0043] The application of a modified acrylic aqueous emulsion can be used for impregnating the surface of paper filter materials or fiber filter materials. In this embodiment, it can be specifically applied to impregnating the surface of a fiberglass filter felt.

[0044]

Example 4

Example 1

[0045] In this embodiment, the functional monomers include 30 g of hydroxyethyl acrylate, 7.5 g of acrylonitrile, and 7.5 g of hexafluorobutyl acrylate.

[0046]

Example 5

Example 1

[0047] In this embodiment, the fluorinated acrylate is specifically selected as hexafluorobutyl methacrylate.

[0048]

Example 6

Example 1

[0049] In this embodiment, the fluorinated acrylate is specifically selected as dodecafluoroheptyl acrylate.

[0050]

Example 7

Example 1

[0051] In this embodiment, the nano-cellulose liquid is specifically selected as a nano-cellulose liquid prepared in

Preparation Example 2

[0052]

Example 8

Example 1

[0053] In this embodiment, the nano-cellulose liquid is specifically selected as a nano-cellulose liquid prepared in

Preparation Example 3

[0054]

Example 9

Example 8

[0055] In this embodiment, in step S4 of the preparation method, a tackifier can be added to the emulsion matrix to improve the initial tack of the aqueous emulsion. Specifically, a preparation method of a modified acrylic aqueous emulsion for improving the initial tack includes the following steps: S1. Take 1 g of emulsifier OP-701 and 150 g of deionized water, stir and mix them thoroughly to obtain a bottoming liquid; take acrylate monomers, functional monomers, the remaining emulsifier and nanocellulose liquid, stir and mix them thoroughly to obtain a pre-emulsified monomer liquid; take potassium persulfate, sodium bicarbonate and the remaining deionized water, stir and mix them thoroughly to obtain an initiator liquid; S2. Stir and heat the bottoming liquid to 83 - 85 °C, then quickly add 10% of the initiator liquid, continuously stir for 5 min, and then start to simultaneously dropwise add the pre-emulsified monomer liquid and the remaining initiator liquid, continuously stir and control the dropping temperature to be maintained at 80 - 82 °C. Among them, the dropping of the pre-emulsified monomer liquid needs to be completed within 4 h, and it is ensured that the initiator liquid finishes dropping 15 min later than the pre-emulsified monomer liquid; S3. After the dropping is completed, further heat the temperature to 86 °C within 30 min and keep it warm for reaction for 1 h to obtain an emulsion matrix; S4. After sampling from the emulsion matrix to smell until there is no obvious pungent smell, when the temperature is cooled to 50 °C, add a tackifier to the emulsion matrix, keep the temperature and continuously stir and mix for 5 min, then cool the temperature to below 40 °C again and filter through a nylon cloth to obtain a modified acrylic aqueous emulsion.

[0056] In this embodiment, the tackifier added in step S4 is prepared by dissolving terpene resin in 2 times the mass of xylene, and the addition amount of the terpene resin is 5% of the sum of the added masses of the acrylate monomers and the functional monomers, that is, 12.25 g.

[0057]

Example 10

Example 9

[0058] In this embodiment, the tackifier added in step S4 is prepared by dissolving rosin in 2 times the mass of xylene, and the addition amount of the rosin is 8% of the sum of the added masses of the acrylate monomers and the functional monomers, that is, 19.6 g.

[0059] Comparative Example

Comparative Example 1

Example 1

[0060] In this comparative example, fluorinated acrylate is not added to the functional monomer, and an equal amount of 2-hydroxyethyl acrylate is used for replacement. That is, in this comparative example, the functional monomer includes 35 g of 2-hydroxyethyl acrylate and 10 g of acrylonitrile.

[0061]

Comparative Example 2

Example 1

[0062] In this comparative example, an equal amount of deionized water was used to replace the nano-cellulose liquid.

[0063] Performance test data Preparation of samples to be tested: The PET non-woven filter cloth was impregnated with the aqueous emulsions prepared in each example and comparative example respectively, and after taking out, it was left to air dry for no less than 24 h to obtain the samples to be tested of the aqueous emulsions in each example and comparative example. In addition, a PET non-woven filter cloth not impregnated with the aqueous emulsion was set as a blank group. Among them, the PET non-woven filter cloth was specifically purchased as MGPT-60 from Mingguan.

[0064] 1. Subjective detection: The appearance performance and initial touch feel of each sample to be tested were compared by means of visual inspection, direct touch, rubbing, etc. Then, the sample to be tested was immersed in water at 80 °C for 48 h, and then fully rubbed for 10 s to observe the surface coating state. Among them, the subjective evaluation criteria for the initial touch feel were: soft < relatively soft < relatively hard < hard.

[0065] 2. Stain resistance test: The test was carried out with reference to Section 7.2 Solid staining method in "GB / T 30159.1-2013 Textiles - Detection and evaluation of anti-fouling properties - Part 1: Resistance to staining", and the staining grade of each sample to be tested was recorded.

[0066] 3. High-temperature oil pressure resistance: First, the tensile strength in the CD direction of each sample to be tested was measured, and then each sample to be tested was placed in hydraulic oil at 150 °C and soaked for 96 h. Then, after taking out and using absorbent paper to remove the excess hydraulic oil on the opposite side, the tensile strength in the CD direction was detected again, and the tensile strength (N / 5 cm) in the CD direction of each sample to be tested was recorded.

[0067] Table 1 Partial performance test data of the modified acrylic aqueous emulsion Combining Example 1, Comparative Examples 1-2 and the blank group and the data in Table 1, it can be seen that Example 1 uses a small amount of fluorinated acrylate as a functional monomer and cooperates with nanocellulose to modify the acrylic aqueous emulsion. Compared with the modification using only fluorinated acrylate or nanocellulose, the prepared aqueous emulsion has better film-forming properties, and when the aqueous emulsion is applied to the PET non-woven filter cloth, it can not only improve the feel of the filter material, but also the formed coating has excellent stain resistance, hot oil resistance and mechanical strength, so that the comprehensive performance of the filter material is better. This may be because fluorinated acrylates can impart lower surface energy and hydrophobicity to the emulsion through fluorine atoms, thereby further enhancing the spreadability and wettability of the emulsion on substrates such as fiber filter materials. At the same time, low surface energy and high hydrophobicity are also beneficial to improving the water resistance and stain resistance of the coating after drying and film formation. In addition, due to the unique structure and excellent mechanical reinforcement properties of nanocellulose, when it is mixed with fluorinated acrylates in a certain proportion and added, a nanofiber network structure can be formed in the emulsion, further stabilizing the emulsion system, and then the aqueous emulsion can form a more uniform and dense coating on the surface of the fiber filter material, which is beneficial to improving the physical and chemical properties of the coating, such as adhesion, coating hardness, tensile strength or hot oil resistance, and can further improve the surface modification effect of the filter material.

[0068] Combining Example 1 and Example 4-6 and the data in Table 1, it can be seen that under the same amount of nanocellulose added, as the proportion of fluorinated acrylate added increases, the coating formed by the aqueous emulsion has better stain resistance and mechanical strength. When hexafluorobutyl methacrylate is used instead of hexafluorobutyl acrylate, although the mechanical strength of the coating formed by the aqueous emulsion can be improved to a certain extent, the presence of the side chain methyl group may affect the shielding effect of the fluorine atom, so the surface energy of the aqueous emulsion will be slightly higher, and the water resistance and stain resistance of the coating formed by it are poor. In addition, when dodecafluoroheptyl acrylate is used instead of hexafluorobutyl acrylate, the obtained aqueous emulsion and the coating formed by the emulsion have further improvements in many aspects, but the price of dodecafluoroheptyl acrylate is high. Without considering the price cost, dodecafluoroheptyl acrylate or dodecafluoroheptyl methacrylate can still be used to modify the acrylic aqueous emulsion in combination with nanocellulose.

[0069] Combined with Example 1 and Examples 7 - 8 and the data in Table 1, it can be seen that under the same addition of fluorinated acrylate, as the addition amount of nanocellulose increases, the coating formed by the aqueous emulsion exhibits harder physical properties and higher tensile strength, and the stain resistance of the coating also has a slight improvement. In addition, when carboxylated nanocellulose is specifically selected as the nanocellulose and mixed with 1,1,1,3,3,3 - hexafluorobutyl acrylate according to a certain mass ratio, the prepared aqueous emulsion is similar in performance to the aqueous emulsion prepared with 1,1,1,2,2,3,3,4,4,5,5,6,6 - tridecafluoro - 1 - hexyl acrylate, which is beneficial to preparing an acrylic aqueous emulsion with better performance at a lower cost. This may be because a large number of carboxyl groups are introduced on the surface of carboxylated nanocellulose, making its dispersibility and stability in water and emulsion better than ordinary nanocellulose, and the carboxyl groups provide more reaction sites, enabling carboxylated nanocellulose to fully react with other molecules, indirectly increasing the monomer conversion rate of the aqueous emulsion, improving the emulsifying performance and film - forming performance of the aqueous emulsion, and thus can make up for the deficiencies in performance to a certain extent.

[0070] Combined with Examples 8 - 10 and the data in Table 1, it can be seen that adding a small amount of tackifier during the preparation of the aqueous emulsion can not only effectively improve the initial tack of the aqueous emulsion, which is beneficial to improving the adhesion of the aqueous emulsion, but also is beneficial to improving the mechanical strength and heat - resistant oiliness of the coating formed by the emulsion.

[0071] This specific embodiment is only an interpretation of the present application and does not limit the present application. After reading this specification, those skilled in the art can make modifications to this specific embodiment without creative contributions as needed, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. A modified acrylic acid aqueous emulsion, characterized in that: Including the following raw materials by weight: Acrylate monomer: 180-220 parts; Functional monomer: 45-60 parts; Nanocellulose liquid: 3-5 parts; Emulsifier: 4-6 parts; Initiator: 1.5-2 parts; Sodium bicarbonate: 2-3 parts; Deionized water: 275-300 parts; The functional monomers are hydroxy acrylate, acrylonitrile and fluorine-containing acrylate mixed in a mass ratio of (4-10):(1-2):

1.

2. A modified acrylic acid aqueous emulsion according to claim 1, characterized in that : The fluorine-containing acrylate is one of hexafluorobutyl acrylate, hexafluorobutyl methacrylate, dodecafluoroheptyl acrylate or dodecafluoroheptyl methacrylate.

3. A modified acrylic acid aqueous emulsion according to claim 1, characterized in that The nanocellulose liquid is prepared by mixing nanocellulose and deionized water, and the solid content of the nanocellulose liquid is 2%-5%.

4. A modified acrylic acid aqueous emulsion according to claim 3, characterized in that : The fluorine-containing acrylate is specifically selected from hexafluorobutyl acrylate, and the mass ratio of hexafluorobutyl acrylate to the solid effective substance in the nanocellulose liquid is (20-75):

1.

5. A modified acrylic acid aqueous emulsion according to claim 4, characterized in that : The nanocellulose is specifically selected from carboxylated nanocellulose.

6. A modified acrylic acid aqueous emulsion according to claim 1, characterized in that : The emulsifier is an alkylphenol polyoxyethylene ether emulsifier, and the initiator is one of potassium persulfate or ammonium persulfate.

7. A method for preparing a modified acrylic acid aqueous emulsion, for preparing a modified acrylic acid aqueous emulsion according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. Take 20% of emulsifier and 55% of deionized water, stir and mix them thoroughly to obtain a base liquid; take acrylate monomer, functional monomer, 80% of emulsifier and nanocellulose liquid, stir and mix them thoroughly to obtain a pre-emulsified monomer liquid; take initiator, sodium bicarbonate and 40% of deionized water, stir and mix them thoroughly to obtain an initiator liquid; S2. Stir and heat the base liquid to 83-85°C, then quickly add 10% of the initiator liquid, continue stirring for 3-5 minutes, and then start to drip the pre-emulsified monomer liquid and the remaining initiator liquid at the same time, continue stirring and control the dripping temperature to maintain at 80-82°C, wherein the dripping of the pre-emulsified monomer liquid must be completed within 4 hours, and ensure that the dripping of the initiator liquid is completed 15-20 minutes later than the pre-emulsified monomer liquid; S3, after the dropwise addition is completed, the temperature is further heated to 86-88°C within 30 minutes, and the temperature is kept for reaction for another 1-2 hours to obtain an emulsion matrix; S4. After taking a sample from the emulsion matrix and smelling it until there is no obvious irritating odor, the sample is cooled to below 40° C. and filtered to obtain a modified acrylic acid aqueous emulsion.

8. The method for preparing a modified acrylic acid aqueous emulsion according to claim 7, characterized in that In step S4, when the emulsion matrix is ​​cooled to 50-55° C., a tackifier may be added to the emulsion matrix, wherein the steps of adding the tackifier are as follows: After taking a sample from the emulsion matrix and smelling it until there is no obvious irritating odor, the sample is cooled to 50-52° C., a tackifier is added, the temperature is maintained and the mixture is stirred and mixed evenly, and then the sample is cooled to below 40° C. and filtered to obtain a modified acrylic water-based emulsion.

9. The method for preparing a modified acrylic acid aqueous emulsion according to claim 8, characterized in that The tackifier is prepared by dissolving a tackifier resin in 2 parts by mass of xylene, wherein the added amount of the tackifier resin is 5%-8% of the sum of the added mass of the acrylate monomer and the functional monomer, wherein the tackifier resin is one of a terpene resin or a rosin.

10. An application of a modified acrylic acid aqueous emulsion, applicable to an aqueous emulsion prepared by the method for preparing a modified acrylic acid aqueous emulsion according to any one of claims 7 to 9, characterized in that : Used for surface impregnation treatment of paper filter material or fiber filter material.

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