A nanocellulose modified acrylic water-based emulsion, a preparation method and application thereof

Abstract

The application discloses a kind of nanocellulose modified acrylic water-based emulsion and its preparation method and application, it is related to the technical field of polymer composite.A kind of modified acrylic water-based emulsion includes 180-220 parts of acrylate monomer, 45-60 parts of functional monomer, 3-5 parts of nanocellulose liquid, 4-6 parts of emulsifier, 1.5-2 parts of initiator, 2-3 parts of sodium bicarbonate and 275-300 parts of deionized water, wherein functional monomer includes hydroxy acrylate, acrylonitrile and fluorine-containing acrylate.By using fluorine-containing acrylate with nanocellulose to modify acrylic emulsion, water-based emulsion with good film-forming performance can be prepared, and the formed coating has good adhesion, stain resistance, heat oil resistance and mechanical strength, if the water-based emulsion is applied to the surface modification of filter material, not only can improve the hand feeling of filter material, but also can improve the stain resistance and service life of filter material surface.

Description

Technical Field

[0001] This invention relates to the technical field of polymer composite materials, and in particular to a nanocellulose-modified acrylic aqueous emulsion, its preparation method, and its application. Background Technology

[0002] Filters play a vital role in modern industry and daily life, and are widely used in air purification, water treatment, food processing, and many other fields. However, because the filter media of traditional filters are mostly made of fiber composites or non-woven fabrics, their dirt resistance is poor, making them susceptible to environmental contamination and resulting in a short lifespan. Therefore, they still have many limitations in use.

[0003] To improve the performance of filter media, existing technologies often use aqueous emulsions to impregnate and modify the surface of filter media. Aqueous emulsions used for surface modification of filter media generally have good film-forming properties and water resistance, and can form a protective layer on the surface of filter media. This can not only improve the physical strength (such as stiffness and burst strength) and structural strength of filter media to a certain extent, but also give the filter media a certain surface anti-fouling ability.

[0004] However, traditional water-based emulsions for surface modification of filter media mostly use thermosetting phenolic resins, which still have shortcomings in terms of durability and environmental friendliness. For example, the impregnated filter media lacks flexibility, is brittle, and is prone to detachment, breakage, or aging. Furthermore, the production process consumes large amounts of solvents that are difficult to recycle, causing environmental pollution. Therefore, developing an environmentally friendly water-based 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 friendliness of the coating formed by modifying the surface of filter media with water-based emulsion, thereby improving the dirt resistance and service life of the filter media after impregnation, this application provides a nanocellulose-modified acrylic water-based emulsion, its preparation method and application.

[0006] Firstly, the modified acrylic aqueous emulsion provided in this application adopts the following technical solution:

[0007] A modified acrylic aqueous emulsion, comprising the following raw materials in parts by weight:

[0008] Acrylate monomer: 180-220 parts;

[0009] Functional monomers: 45-60 parts;

[0010] Nanocellulose solution: 3-5 parts;

[0011] Emulsifier: 4-6 parts;

[0012] Initiator: 1.5-2 parts;

[0013] Sodium bicarbonate: 2-3 parts;

[0014] Deionized water: 275-300 parts;

[0015] 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 hydroxy acrylate, acrylonitrile and fluorinated acrylate in a mass ratio of (4-10):(1-2):1.

[0016] By adopting the above technical solution, an aqueous emulsion with good film-forming properties can be obtained. Furthermore, the coating formed by the aqueous emulsion exhibits good adhesion, stain resistance, heat and oil resistance, and mechanical strength. If this aqueous emulsion is applied to the surface modification of filter media, it can not only improve the overall flexibility and feel of the filter media, but also enhance the stain resistance and service life of the filter media surface, reducing the occurrence of peeling, cracking, or aging of the modified coating. In addition, the above raw materials use deionized water as the main solvent, eliminating the need for large quantities of difficult-to-recover solvents during production and avoiding environmental pollution. It is not only easy to process but also meets environmental protection requirements, possessing broad application prospects and market value.

[0017] Optionally, the fluorinated acrylate is one of hexafluorobutyl acrylate, hexafluorobutyl methacrylate, dodecafluoroheptyl acrylate, or dodecafluoroheptyl methacrylate.

[0018] By adopting the above technical solutions, the physical and chemical properties of waterborne emulsions can be adjusted using different fluorinated acrylates, enabling the coatings formed to meet the needs of filter materials of various types. Furthermore, by introducing fluorine atoms into the waterborne emulsions using these fluorinated acrylates, environmentally friendly waterborne emulsions with superior performance compared to existing emulsions can be prepared without consuming large amounts of difficult-to-recover solvents, thus meeting the demands of current industrial development.

[0019] Optionally, the nanocellulose solution is prepared by mixing nanocellulose with deionized water, and the solid content of the nanocellulose solution is 2%-5%.

[0020] By adopting the above technical solution, the amount of nanocellulose added can be controlled within a reasonable range. This is beneficial for modifying acrylic waterborne emulsions in combination with fluorinated acrylates, so that the coating formed by the waterborne emulsion has better overall performance. It also helps to prevent the waterborne emulsion from becoming too viscous during mixing or becoming too hard and brittle after coating due to excessive addition of nanocellulose.

[0021] Optionally, the fluorinated acrylate is specifically selected as hexafluorobutyl acrylate, and the mass ratio of hexafluorobutyl acrylate to the solid effective substance in the nanocellulose liquid is (20-75):1.

[0022] By adopting the above technical solution, a modified acrylic aqueous emulsion with good overall performance can be obtained. Although the performance of the resulting aqueous emulsion is still somewhat inferior to that of the aqueous emulsion prepared using dodecafluoroheptyl acrylate, the overall raw material cost is lower, the cost-effectiveness is higher, and it has higher market value. In addition, the preparation of hexafluorobutyl acrylate is more environmentally friendly and safer than that of dodecafluoroheptyl acrylate, conforms to green processes, and has a certain degree of environmental friendliness.

[0023] Optionally, the nanocellulose may be specifically selected as carboxylated nanocellulose.

[0024] By adopting the above technical solution, the carboxyl groups on the surface of carboxylated nanocellulose can provide more reaction sites, enabling nanocellulose to fully react and connect with other molecules. This is beneficial for improving the monomer conversion rate of aqueous emulsions, and further improving the emulsifying and film-forming properties of aqueous emulsions. Furthermore, using carboxylated nanocellulose in combination with hexafluorobutyl acrylate to modify acrylic aqueous emulsions results in aqueous emulsions with similar overall performance but significantly lower raw material costs compared to those modified with dodecafluoroheptyl acrylate. This improves the cost-effectiveness of aqueous emulsions, giving them broad application prospects and market value.

[0025] Optionally, the emulsifier is an alkylphenol polyoxyethylene ether emulsifier, and the initiator is either potassium persulfate or ammonium persulfate.

[0026] Secondly, the method for preparing a modified acrylic aqueous emulsion provided in this application adopts the following technical solution:

[0027] A method for preparing a modified acrylic aqueous emulsion includes the following steps:

[0028] S1. By weight, take 20% emulsifier and 55% deionized water and mix thoroughly to obtain the base liquid; take acrylate monomer, functional monomer, 80% emulsifier and nanocellulose liquid and mix thoroughly to obtain the pre-emulsified monomer liquid; take initiator, sodium bicarbonate and 40% deionized water and mix thoroughly to obtain the initiator liquid.

[0029] S2. Stir and heat the bottom liquid to 83-85℃, then quickly add 10% initiator solution. After stirring continuously for 3-5 minutes, start to add the pre-emulsified monomer solution and the remaining initiator solution dropwise simultaneously. Continue stirring and control the dropwise temperature to maintain at 80-82℃. The dropwise addition of the pre-emulsified monomer solution must be completed within 4 hours, and the initiator solution must be added 15-20 minutes later than the pre-emulsified monomer solution.

[0030] S3. After the addition is complete, the temperature is further heated to 86-88℃ within 30 minutes, and the reaction is maintained at this temperature for 1-2 hours to obtain the emulsion matrix.

[0031] S4. After taking a sample from the emulsion matrix and smelling it until there is no obvious irritating odor, cool it down to below 40°C and filter it to obtain a modified acrylic water-based emulsion.

[0032] By adopting the above technical solution, the preparation method is simple, and the production process does not require the consumption of a large amount of solvents that are not easy to recycle, which has a certain degree of environmental friendliness.

[0033] Optionally, in step S4, when the emulsion matrix cools to 50-55°C, a thickener can be added to the emulsion matrix, wherein the steps for adding the thickener are as follows:

[0034] After taking a sample from the emulsion matrix and smelling it until there is no obvious irritating odor, the temperature is lowered to 50-52℃, a thickener is added, the temperature is maintained and the mixture is stirred continuously until homogeneous, and then the temperature is lowered to below 40℃ and filtered to obtain a modified acrylic water-based emulsion.

[0035] Optionally, the tackifier is prepared by dissolving a tackifying resin in 2 parts by weight of xylene, wherein the amount of the tackifying resin added is 5%-8% of the sum of the mass of the acrylate monomer and the functional monomer, and wherein the tackifying resin is one of terpene resin or rosin.

[0036] By adopting the above technical solution, adding either terpene resin or rosin as a tackifier to the water-based emulsion can not only effectively improve the initial tack of the water-based emulsion and improve the adhesion of the coating, but also improve the mechanical strength and heat resistance of the coating and extend the service life of the coating.

[0037] Thirdly, the application of the modified acrylic aqueous emulsion provided in this application adopts the following technical solution:

[0038] A modified acrylic aqueous emulsion application for surface impregnation treatment of paper or fiber filter media.

[0039] By adopting the above technical solutions, it is beneficial to improve the softness, dirt resistance and service life of impregnated paper or fiber filter media.

[0040] In summary, the technical solution of this application possesses at least one of the following beneficial effects:

[0041] 1. By using a small amount of fluorinated acrylate as a functional monomer and modifying acrylic aqueous emulsion with nanocellulose, 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.

[0042] 2. By selecting carboxylated nanocellulose and mixing it with hexafluorobutyl acrylate in a certain mass ratio to modify acrylic waterborne emulsions, waterborne emulsions with excellent comprehensive performance and low cost can be obtained, which have broad application prospects and market value.

[0043] 3. Applying the modified acrylic aqueous emulsion prepared above to the impregnation treatment of paper filter media or fiber filter media is beneficial to improving the dirt resistance and service life of the impregnated filter media. Detailed Implementation

[0044] The present application will be further described in detail below with reference to preparation examples, embodiments and comparative examples.

[0045] Preparation Example

[0046]

Preparation Example 1

[0047] The preparation of a nanocellulose solution includes the following steps:

[0048] Take 1g of nanocellulose powder and 49g of deionized water, and thoroughly pulverize and mix them using ultrasound to obtain a nanocellulose solution with a solid content of 2%.

[0049]

Preparation Example 2

[0050] The preparation of a nanocellulose solution includes the following steps:

[0051] Take 2.5g of nanocellulose powder and 47.5g of deionized water, and mix them thoroughly by ultrasonic stirring to obtain a nanocellulose solution with a solid content of 5%.

[0052]

Preparation Example 3

[0053] The preparation of a nanocellulose solution includes the following steps:

[0054] Take 2.5g of carboxylated nanocellulose powder and 47.5g of deionized water, and mix them thoroughly by ultrasonic stirring to obtain a carboxylated nanocellulose solution with a solid content of 5%.

[0055] Example

[0056]

Example 1

[0057] A modified acrylic aqueous emulsion comprises the following raw materials: 200g acrylate monomer, 45g functional monomer, 5g nanocellulose liquid, 5g emulsifier, 2g potassium persulfate, 2g sodium bicarbonate, and 275g deionized water.

[0058] The acrylate monomers include 150g of ethyl acrylate and 50g of butyl acrylate; the functional monomers include 30g of hydroxyethyl acrylate, 10g of acrylonitrile and 5g of fluorinated acrylate. In this embodiment, the fluorinated acrylate is specifically hexafluorobutyl acrylate; the nanocellulose liquid is specifically the nanocellulose liquid prepared in [Preparation Example 1]; the emulsifiers are specifically 3g of emulsifier OP-701 and 2g of emulsifier OP-205.

[0059] A method for preparing a modified acrylic aqueous emulsion includes the following steps:

[0060] S1. Take 1g of emulsifier OP-701 and 150g of deionized water and mix thoroughly to obtain the bottom solution; take acrylate monomer, functional monomer, the remaining emulsifier and nanocellulose solution and mix thoroughly to obtain the pre-emulsified monomer solution; take potassium persulfate, sodium bicarbonate and the remaining deionized water and mix thoroughly to obtain the initiator solution.

[0061] S2. Stir and heat the bottom liquid to 83-85℃, then quickly add 10% initiator solution. After stirring continuously for 5 minutes, start to add the pre-emulsified monomer solution and the remaining initiator solution dropwise simultaneously. Continue stirring and control the dropwise temperature to maintain at 80-82℃. The dropwise addition of the pre-emulsified monomer solution must be completed within 4 hours, and the initiator solution must be added 15 minutes later than the pre-emulsified monomer solution.

[0062] S3. After the addition is complete, the temperature is further heated to 86℃ within 30 minutes and kept at this temperature for another 1 hour to obtain the emulsion matrix; S4. After taking a sample from the emulsion matrix and smelling it until there is no obvious irritating odor, the temperature is lowered to below 40℃ and filtered through nylon cloth to obtain a modified acrylic water-based emulsion.

[0063] An application of a modified acrylic aqueous emulsion is provided for impregnating the surface of paper or fiber filter media. In this embodiment, it is specifically applied to impregnating the surface of PET nonwoven filter media.

[0064]

Example 2

[0065] A modified acrylic aqueous emulsion comprises the following raw materials: 180g acrylate monomer, 55g functional monomer, 3g nanocellulose liquid, 4g emulsifier, 1.5g potassium persulfate, 2g sodium bicarbonate and 275g deionized water.

[0066] The acrylate monomers include 130g of ethyl acrylate and 50g of butyl acrylate; the functional monomers include 40g of hydroxyethyl acrylate, 10g of acrylonitrile and 5g of fluorinated acrylate. In this embodiment, the fluorinated acrylate is specifically hexafluorobutyl methacrylate; the nanocellulose liquid is specifically the nanocellulose liquid prepared in [Preparation Example 2]; the emulsifiers include 2g of emulsifier OP-701 and 2g of emulsifier OP-205.

[0067] A method for preparing a modified acrylic aqueous emulsion includes the following steps:

[0068] S1. Take 1g of emulsifier OP-701 and 150g of deionized water and mix thoroughly to obtain the bottom solution; take acrylate monomer, functional monomer, the remaining emulsifier and nanocellulose solution and mix thoroughly to obtain the pre-emulsified monomer solution; take potassium persulfate, sodium bicarbonate and the remaining deionized water and mix thoroughly to obtain the initiator solution.

[0069] S2. Stir and heat the bottom liquid to 83-85℃, then quickly add 10% initiator solution. After stirring continuously for 5 minutes, start to add the pre-emulsified monomer solution and the remaining initiator solution dropwise simultaneously. Continue stirring and control the dropwise temperature to maintain at 80-82℃. The dropwise addition of the pre-emulsified monomer solution must be completed within 4 hours, and the initiator solution must be added 15 minutes later than the pre-emulsified monomer solution.

[0070] S3. After the addition is complete, the temperature is further heated to 88℃ within 30 minutes and kept at this temperature for another 2 hours to obtain the emulsion matrix; S4. After taking a sample from the emulsion matrix and smelling it until there is no obvious irritating odor, the temperature is lowered to below 40℃ and filtered through nylon cloth to obtain a modified acrylic water-based emulsion.

[0071] An application of a modified acrylic aqueous emulsion is provided for impregnating the surface of paper or fiber filter media. In this embodiment, it is specifically applied to impregnating the surface of PE nonwoven filter cloth.

[0072]

Example 3

[0073] A modified acrylic aqueous emulsion comprises the following raw materials: 220g acrylate monomer, 60g functional monomer, 5g nanocellulose liquid, 6g emulsifier, 2g ammonium persulfate, 3g sodium bicarbonate and 300g deionized water.

[0074] The acrylate monomers include 180g of ethyl acrylate and 40g of butyl acrylate; the functional monomers include 50g of hydroxyethyl acrylate, 5g of acrylonitrile, and 5g of fluorinated acrylate. In this embodiment, the fluorinated acrylate is specifically dodecafluoroheptyl acrylate; the nanocellulose liquid is specifically the nanocellulose liquid prepared in [Preparation Example 1]; the emulsifiers include 4g of emulsifier OP-701 and 2g of emulsifier OP-205.

[0075] A method for preparing a modified acrylic aqueous emulsion includes the following steps:

[0076] S1. Take 1g of emulsifier OP-701 and 150g of deionized water and mix thoroughly to obtain the bottom solution; take acrylate monomer, functional monomer, the remaining emulsifier and nanocellulose solution and mix thoroughly to obtain the pre-emulsified monomer solution; take potassium persulfate, sodium bicarbonate and the remaining deionized water and mix thoroughly to obtain the initiator solution.

[0077] S2. Stir and heat the bottom liquid to 83-85℃, then quickly add 10% initiator solution. After stirring continuously for 5 minutes, start to add the pre-emulsified monomer solution and the remaining initiator solution dropwise simultaneously. Continue stirring and control the dropwise temperature to maintain at 80-82℃. The dropwise addition of the pre-emulsified monomer solution must be completed within 4 hours, and the initiator solution must be added 20 minutes later than the pre-emulsified monomer solution.

[0078] S3. After the addition is complete, the temperature is further heated to 88℃ within 30 minutes and kept at this temperature for another 1 hour to obtain the emulsion matrix; S4. After taking a sample from the emulsion matrix and smelling it until there is no obvious irritating odor, the temperature is lowered to 50℃, a thickener is added to the emulsion matrix, and the temperature is maintained and stirred continuously for 5 minutes. Then the temperature is lowered again to below 40℃ and filtered through nylon cloth to obtain a modified acrylic water-based emulsion.

[0079] In step S4, the thickener added is prepared by dissolving terpene resin in 2 parts by mass of xylene, wherein the amount of terpene resin added is 5% of the sum of the added mass of acrylate monomer and functional monomer, i.e., 14g.

[0080] An application of a modified acrylic aqueous emulsion is provided for impregnating the surface of paper or fiber filter media. In this embodiment, it is specifically applied to impregnating the surface of glass fiber filter media felt.

[0081]

Example 4

[0082] A modified acrylic aqueous emulsion differs from [Example 1] in that the proportion and amount of fluorinated acrylate in the functional monomers are different.

[0083] In this embodiment, the functional monomers include 30g of hydroxyethyl acrylate, 7.5g of acrylonitrile, and 7.5g of hexafluorobutyl acrylate.

[0084]

Example 5

[0085] A modified acrylic aqueous emulsion differs from [Example 1] in that the functional monomer contains a different fluorinated acrylate.

[0086] In this embodiment, the fluorinated acrylate is specifically selected as hexafluorobutyl methacrylate.

[0087]

Example 6

[0088] A modified acrylic aqueous emulsion differs from [Example 1] in that the functional monomer contains a different fluorinated acrylate.

[0089] In this embodiment, the fluorinated acrylate is specifically selected as dodecafluoroheptyl acrylate.

[0090]

Example 7

[0091] A modified acrylic aqueous emulsion, which differs from [Example 1] in that it uses a different nanocellulose liquid.

[0092] In this embodiment, the nanocellulose liquid is specifically selected from the nanocellulose liquid prepared in [Preparation Example 2], that is, in this embodiment, the solid content of the nanocellulose liquid is 5%.

[0093]

Example 8

[0094] A modified acrylic aqueous emulsion, which differs from [Example 1] in that it uses a different nanocellulose liquid.

[0095] In this embodiment, the nanocellulose solution specifically used is the nanocellulose solution prepared in [Preparation Example 3].

[0096]

Example 9

[0097] A modified acrylic aqueous emulsion differs from [Example 8] in that it is prepared using a different method.

[0098] In this embodiment, in step S4 of the preparation method, a thickener can be added to the emulsion matrix to improve the initial tack of the aqueous emulsion. Specifically, a method for preparing a modified acrylic aqueous emulsion with improved initial tack includes the following steps:

[0099] S1. Take 1g of emulsifier OP-701 and 150g of deionized water and mix thoroughly to obtain the bottom solution; take acrylate monomer, functional monomer, the remaining emulsifier and nanocellulose solution and mix thoroughly to obtain the pre-emulsified monomer solution; take potassium persulfate, sodium bicarbonate and the remaining deionized water and mix thoroughly to obtain the initiator solution.

[0100] S2. Stir and heat the bottom liquid to 83-85℃, then quickly add 10% initiator solution. After stirring continuously for 5 minutes, start to add the pre-emulsified monomer solution and the remaining initiator solution dropwise simultaneously. Continue stirring and control the dropwise temperature to maintain at 80-82℃. The dropwise addition of the pre-emulsified monomer solution must be completed within 4 hours, and the initiator solution must be added 15 minutes later than the pre-emulsified monomer solution.

[0101] S3. After the addition is complete, the temperature is further heated to 86℃ within 30 minutes and kept at this temperature for another 1 hour to obtain the emulsion matrix; S4. After taking a sample from the emulsion matrix and smelling it until there is no obvious irritating odor, the temperature is lowered to 50℃, a thickener is added to the emulsion matrix, and the temperature is maintained and stirred continuously for 5 minutes. Then the temperature is lowered again to below 40℃ and filtered through nylon cloth to obtain a modified acrylic water-based emulsion.

[0102] In this embodiment, the tackifier added in step S4 is prepared by dissolving terpene resin in 2 parts by weight of xylene, wherein the amount of terpene resin added is 5% of the sum of the added mass of acrylate monomer and functional monomer, i.e., 12.25g.

[0103]

Example 10

[0104] A modified acrylic aqueous emulsion, which differs from [Example 9] in that it contains a different thickener.

[0105] In this embodiment, the tackifier added in step S4 is prepared by dissolving rosin in 2 parts by weight of xylene, wherein the amount of rosin added is 8% of the sum of the added mass of acrylate monomer and functional monomer, i.e., 19.6g.

[0106] Comparative Example

[0107] Comparative Example 1

[0108] An acrylic aqueous emulsion differs from [Example 1] in that it uses different functional monomers.

[0109] In this comparative example, no fluorinated acrylates were added to the functional monomers, and an equal amount of hydroxyethyl acrylate was used as a substitute. That is, in this comparative example, the functional monomers consisted of 35g of hydroxyethyl acrylate and 10g of acrylonitrile.

[0110] Comparative Example 2

[0111] An acrylic aqueous emulsion, which differs from [Example 1] in that it does not contain nanocellulose liquid.

[0112] In this comparative example, an equal amount of deionized water was used instead of nanocellulose solution.

[0113] Performance test data

[0114] Sample preparation: PET nonwoven filter cloth was impregnated with the aqueous emulsions prepared in each example and comparative example. After removal, it was allowed to air dry for at least 24 hours to obtain the test samples of the aqueous emulsions in each example and comparative example. Additionally, PET nonwoven filter cloth not impregnated with the aqueous emulsion was set up as a blank group. The PET nonwoven filter cloth was specifically purchased from Mingguan MGPT-60.

[0115] 1. Subjective Testing: The appearance and initial tactile feel of each sample were compared through visual inspection, direct touch, and rubbing. The samples were then immersed in 80℃ water for 48 hours, followed by thorough rubbing for 10 seconds, and the surface coating condition was observed. The subjective evaluation criteria for the initial tactile feel were: soft < relatively soft < relatively hard < hard.

[0116] 2. Stain resistance test: The solid staining method in section 7.2 of GB / T 30159.1-2013 Textiles - Test and evaluation of stain resistance - Part 1: Stain resistance was used for the test, and the staining level of each sample was recorded.

[0117] 3. High-temperature hydraulic resistance: First, measure the tensile strength of each sample in the CD direction. Then, immerse each sample in hydraulic oil at 150℃ for 96 hours. After removing the oil-absorbing paper to remove excess hydraulic oil, test the tensile strength in the CD direction again and record the tensile strength (N / 5cm) of each sample in the CD direction.

[0118] Table 1. Partial performance test data of modified acrylic waterborne emulsion.

[0119]

[0120]

[0121] Based on the data from Example 1, Comparative Examples 1-2, and the blank group, and referring to Table 1, it can be seen that Example 1, by using a small amount of fluorinated acrylate as a functional monomer and combining it with nanocellulose to modify the acrylic aqueous emulsion, produces an aqueous emulsion with better film-forming properties compared to using fluorinated acrylate or nanocellulose alone for modification. Moreover, when the aqueous emulsion is applied to PET nonwoven filter cloth, it not only improves the feel of the filter material, but also forms a coating with excellent stain resistance, heat and oil resistance, and mechanical strength, making the overall performance of the filter material better. This may be because fluorinated acrylates can impart lower surface energy and hydrophobicity to the emulsion through fluorine atoms, which further enhances the spreadability and wettability of the emulsion on substrates such as fiber filter media. 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 reinforcing properties of nanocellulose, when mixed with fluorinated acrylates in a certain proportion, a nanofiber network structure can be formed in the emulsion, further stabilizing the emulsion system. As a result, the aqueous emulsion can form a more uniform and dense coating on the surface of the fiber filter media, which is beneficial to improving the physical and chemical properties of the coating, such as adhesion, coating hardness, tensile strength or heat and oil resistance, and can further improve the surface modification effect of the filter media.

[0122] Combining Examples 1 and 4-6 with the data in Table 1, it can be seen that, with the same amount of nanocellulose added, the coating formed by the aqueous emulsion exhibits better stain resistance and mechanical strength as the proportion of fluorinated acrylate increases. While using hexafluorobutyl methacrylate instead of hexafluorobutyl acrylate can improve the mechanical strength of the coating to some extent, the presence of side-chain methyl groups may affect the shielding effect of fluorine atoms, resulting in a slightly higher surface energy of the aqueous emulsion and poorer water and stain resistance in the resulting coating. Furthermore, using dodecylfluoroheptyl acrylate instead of hexafluorobutyl acrylate further improves the aqueous emulsion and the coating in several aspects. However, dodecylfluoroheptyl acrylate is expensive. Without considering cost, dodecylfluoroheptyl acrylate or dodecylfluoroheptyl methacrylate can still be used in combination with nanocellulose to modify acrylic aqueous emulsions.

[0123] Combining Examples 1 and 7-8 with the data in Table 1, it can be seen that, with the same amount of fluorinated acrylate added, as the amount of nanocellulose added increases, the coating formed by the aqueous emulsion exhibits harder physical properties and higher tensile strength, and the stain resistance of the coating is also slightly improved. Furthermore, when carboxylated nanocellulose is specifically selected and mixed with hexafluorobutyl acrylate at a certain mass ratio, the resulting aqueous emulsion has performance close to that of the aqueous emulsion prepared using dodecafluoroheptyl acrylate, which is beneficial for preparing higher-performance acrylic aqueous emulsions at a lower cost. This may be because the surface of carboxylated nanocellulose introduces a large number of carboxyl groups, making its dispersibility and stability in water and emulsions superior to ordinary nanocellulose. Moreover, the carboxyl groups provide more reaction sites, allowing carboxylated nanocellulose to react fully with other molecules, indirectly improving the monomer conversion rate of the aqueous emulsion, and improving its emulsifying and film-forming properties, thus compensating for some of its performance deficiencies.

[0124] Based on Examples 8-10 and the data in Table 1, it can be seen that adding a small amount of thickener during the preparation of the water-based emulsion can not only effectively improve the initial tack of the water-based emulsion and improve its adhesion, but also improve the mechanical strength and heat resistance of the coating formed by the emulsion.

[0125] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this specific embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A modified acrylic aqueous emulsion, characterized in that, The following ingredients are included by mass parts: 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; The functional monomer is a mixture of hydroxy acrylate, acrylonitrile and fluorine-containing acrylate in a mass ratio of (4-10):(1-2):

1.

2. The modified acrylic 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. The modified acrylic aqueous emulsion according to claim 1, characterized in that 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%.

4. The modified acrylic aqueous emulsion according to claim 3, characterized in that The fluorine-containing 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.

5. The modified acrylic aqueous emulsion according to claim 4, characterized in that The nano-cellulose is specifically carboxylated nano-cellulose.

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

7. A method for preparing a modified acrylic aqueous emulsion according to any one of claims 1 to 6, characterized in that, The following steps are included: S1, by mass parts, 20% emulsifier and 55% deionized water are fully stirred and mixed to obtain a base liquid; acrylate monomer, functional monomer, 80% emulsifier and nano-cellulose liquid are fully stirred and mixed to obtain a pre-emulsified monomer liquid; initiator, sodium bicarbonate and the remaining deionized water are fully stirred and mixed to obtain an initiation liquid; S2, the base liquid is heated to 83-85℃ by stirring, then 10% of the initiation liquid is quickly added, and after 3-5min of continuous stirring, the pre-emulsified monomer liquid and the remaining initiation liquid are simultaneously added dropwise, the temperature is controlled to maintain at 80-82℃ during the dropwise addition, and the dropwise addition of the pre-emulsified monomer liquid needs to be completed within 4h, and the initiation liquid needs to be completed dropwise 15-20min later than the pre-emulsified monomer liquid; S3, after the dropwise addition is completed, the temperature is further heated to 86-88℃ within 30min, and then reacted for 1-2h to obtain a emulsion matrix; S4, after sampling from the emulsion matrix and smelling the taste to no obvious irritating odor, the temperature is reduced to below 40℃ and filtered to obtain a modified acrylic water-based emulsion.

8. The method for preparing a modified acrylic aqueous emulsion according to claim 7, characterized in that In step S4, when the emulsion matrix is cooled to 50-55℃, an adhesion promoter can be added to the emulsion matrix, and the steps of adding the adhesion promoter are as follows: After sampling from the emulsion matrix and smelling the taste to no obvious irritating odor, the temperature is reduced to 50-52℃, the adhesion promoter is added, the temperature is maintained and continuously stirred to mix uniformly, then the temperature is reduced to below 40℃ and filtered to obtain a modified acrylic water-based emulsion.

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

10. Use of a modified aqueous acrylic emulsion, for an aqueous emulsion prepared according to the process of any one of claims 7 to 9, characterized in that It is used for surface impregnation treatment of paper filter material or fiber filter material.

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