A nano-microencapsulated environmentally friendly water- and oil-repellent wax emulsion and its preparation method

Abstract

The present invention relates to the field of wax emulsions, and in particular to a nano-microencapsulated environmentally friendly water- and oil-repellent wax emulsion and a preparation method thereof. The nano-microencapsulated environmentally friendly water- and oil-repellent wax emulsion comprises: carnauba wax, KH570 silane coupling agent, polyoxyethylene octadecyl ether, an emulsifier, an initiator, methyl methacrylate monomer, and deionized water. The preparation method comprises hydrophobically modifying the carnauba wax with a KH570 silane coupling agent, mixing the carnauba wax with polyoxyethylene octadecyl ether and the emulsifier to obtain a composite wax emulsion, and then adding methyl methacrylate monomer dropwise for reaction to obtain a nano-microencapsulated environmentally friendly water- and oil-repellent wax emulsion. The nano-microencapsulated environmentally friendly water- and oil-repellent wax emulsion has the advantages of being water- and oil-repellent, environmentally friendly, highly stable, and food-contactable.

Description

Technical Field

[0001] The present invention relates to the field of wax emulsions, in particular to a nano-microencapsulated environment-friendly water- and oil-repellent wax emulsion and a preparation method thereof. Background Art

[0002] In recent years, the safety and environmental friendliness of food packaging materials have been strictly regulated. Currently, waterproof and oil-proof coatings usually use low-surface-energy materials, mainly fluoropolymers. However, fluoropolymers are difficult to degrade in the environment and are biotoxic, and have been explicitly restricted by the EU REACH regulations and the US FDA. Although petroleum-based wax materials have oil-proof properties, their mineral oil components MOSH / MOAH can accumulate in the human body through migration. The EU Directive 2023 / 903 has limited the migration of MOSH in food contact materials to ≤0.5mg / kg. Although existing synthetic waxes can avoid the risks of mineral oil, their hydrophobic angles are only 95-100°, and their barrier properties to oil and fat are difficult to meet the requirements for high-fat food packaging.

[0003] The World Health Organization's "Guidelines on the Safety of Food Contact Materials" points out that ideal materials must meet the following requirements simultaneously: ① Migration amount <0.01mg / dm²; ② Biodegradation rate >90% (OECD 301B standard); ③ Dynamic contact angle >110°.

[0004] Against the backdrop of increasingly stringent environmental regulations and rising consumer safety demands, this new wax emulsion material must not only possess excellent water and oil repellency but also meet biodegradability and food contact safety requirements to address the dual challenges of sustainable development and health and safety worldwide. Therefore, developing a high-performance water and oil repellent wax emulsion based on environmentally friendly materials has significant technical value and market significance. Summary of the Invention

[0005] In order to meet the requirements of water- and oil-repellent properties of wax emulsion while also having biodegradability and food contact safety, the present application provides a nano-microencapsulated environmentally friendly water- and oil-repellent wax emulsion and a preparation method thereof.

[0006] In the first aspect, the present application provides a nano-microencapsulated environmentally friendly water- and oil-repellent wax emulsion, which adopts the following technical solution:

[0007] A nano-microencapsulated environmentally friendly water- and oil-repellent wax emulsion is prepared from the following raw materials in parts by weight: 70-80 parts of modified wax, 7-13 parts of polyoxyethylene octadecyl ether, 0.4-0.8 parts of emulsifier, 10-20 parts of methyl methacrylate monomer, 0.5-1.5 parts of initiator, and 20-40 parts of deionized water. The modified wax is composed of carnauba wax and KH570 silane coupling agent.

[0008] By adopting the above technical scheme, the modified wax has good hydrophobicity and adhesion to the substrate. The polyoxyethylene octadecyl ether and emulsifier are compounded synergistically to realize a stable dispersion system of nano-microcapsules. The raw material composition is an aqueous solvent-free system, which complies with the requirements of GB 33372-2020 "Limits of Volatile Organic Compounds in Adhesives", reduces the environmental burden during the synthesis process, and conforms to the development trend of green chemistry.

[0009] Preferably, the nano-microencapsulated environmentally friendly water- and oil-repellent wax emulsion is prepared by including the following raw materials in parts by weight: 75 parts of modified wax, 10 parts of polyoxyethylene octadecyl ether, 0.6 parts of emulsifier, 15 parts of methyl methacrylate monomer, 1 part of initiator, and 30 parts of deionized water. The modified wax is composed of carnauba wax and KH570 silane coupling agent.

[0010] Preferably, the modified wax is carnauba wax and KH570 silane coupling agent in a mass ratio of (40-60):1.

[0011] Preferably, the modified wax is carnauba wax and KH570 silane coupling agent in a mass ratio of 50:1.

[0012] Preferably, the polyoxyethylene stearyl ether is any one or more of polyoxyethylene (2) stearyl ether and polyoxyethylene (10) stearyl ether.

[0013] Preferably, the emulsifier is any one or more of sodium polyoxyethylene fatty alcohol ether sulfate, sodium starch octenylsuccinate, alkyl glycoside, sucrose ester, lecithin, and cocamidopropyl betaine. The above emulsifiers all meet environmental protection and food safety standards.

[0014] Preferably, the mass ratio of the initiator, potassium persulfate to sodium bisulfite is (5-8):1.

[0015] Preferably, the mass ratio of the initiator, potassium persulfate to sodium bisulfite is 6.5:1.

[0016] Preferably, the deionized water comprises a first solvent for dissolving polyoxyethylene octadecyl ether, a second solvent for dissolving potassium persulfate, and a third solvent for dissolving sodium bisulfite, wherein the mass ratio of the first solvent, the second solvent, and the third solvent is 8:(1-2):(1-2).

[0017] Preferably, the deionized water comprises a first solvent for dissolving polyoxyethylene octadecyl ether, a second solvent for dissolving potassium persulfate, and a third solvent for dissolving sodium bisulfite, wherein the mass ratio of the first solvent, the second solvent, and the third solvent is 8:1:1.

[0018] In a second aspect, the present application provides a method for preparing a nano-microencapsulated environmentally friendly water- and oil-repellent wax emulsion, using the following technical solution:

[0019] S1: Carnauba wax modification: KH570 silane coupling agent was added to carnauba wax, and the mixture was stirred to obtain modified wax;

[0020] S2: Compounding and emulsification: premix polyoxyethylene octadecyl ether with a first solvent at 60-70°C, stir until a transparent solution is obtained, add the mixture to the modified wax prepared in S1, and then add an emulsifier and stir to obtain a compounded wax emulsion;

[0021] S3: Polymerization: Add citric acid to the compound wax emulsion prepared in S2 to adjust the pH value, add initiator, control the temperature at 40-60°C, and add methyl methacrylate monomer to react to form a nano-encapsulated environmentally friendly water- and oil-repellent wax emulsion.

[0022] By adopting the above technical scheme, the modified wax is prepared by using KH570 silane coupling agent to modify carnauba wax, introducing silicone groups into the carnauba wax molecules, significantly improving the hydrophobicity and interfacial properties of the wax; the method of premixing polyoxyethylene octadecyl ether with hot water is adopted to improve the emulsification efficiency and avoid the problem of particle agglomeration in the emulsification process; nano-microencapsulation technology, through the polymerization reaction of methyl methacrylate monomer, forms polymethyl methacrylate wall material on the surface of the wax emulsion, realizing nano-microencapsulation of the wax emulsion, not only improving the water and oil repellency of the wax emulsion, but also enhancing its stability and durability. The prepared nano-microencapsulated environmentally friendly water and oil repellent wax emulsion has the advantages of water and oil repellency, environmental protection, high stability, uniform coating and rapid film formation.

[0023] Preferably, the method for preparing the nano-microencapsulated environmentally friendly water- and oil-repellent wax emulsion adopts the following technical solution:

[0024] S1: Hydrophobic modification of carnauba wax: Preheat KH570 silane coupling agent to 50-70°C, add carnauba wax, and stir at 80-100°C and ≥500 rpm for 20-40 min to obtain modified wax;

[0025] S2: Compounding and emulsification: premix polyoxyethylene octadecyl ether with a first solvent at 60-70°C, stir until a transparent solution is obtained, add the mixture to the modified wax prepared in S1, and then add an emulsifier. Maintain the temperature at 75-85°C and stir at 300-400 rpm for 10-30 minutes to prepare a compounded wax emulsion.

[0026] S3: Polymerization: Add 0.5% citric acid to the compound wax emulsion prepared in S2 to adjust the pH to 3.5±0.1, add potassium persulfate to the second solvent to dissolve, and add sodium bisulfite to the third solvent to dissolve, and add them slowly. Control the temperature at 40-60°C to avoid excessive local concentration. After mixing, slowly add methyl methacrylate monomer and react at a pressure of 0.2-0.6MPa for 10-20h to form a nano-encapsulated environmentally friendly water- and oil-repellent wax emulsion.

[0027] In summary, this application has the following beneficial effects:

[0028] 1. This application prepares a nano-microencapsulated environmentally friendly water- and oil-repellent wax emulsion to achieve water- and oil-repellent properties, environmental protection, high stability, simple process, and food contact properties.

[0029] 2. This application obtains good hydrophobicity and substrate adhesion by modifying carnauba palm with KH570 silane coupling agent. The aqueous solvent-free raw material system reduces the environmental burden during the synthesis process and is biodegradable and food contact safe.

[0030] 3. The method of the present application, through nano-microencapsulation technology, the polymerization reaction of methyl methacrylate monomer and compound wax emulsion, forms polymethyl methacrylate wall material on the surface of the wax emulsion, which not only obtains the water and oil repellent properties of the wax emulsion, but also enhances its stability and durability. DETAILED DESCRIPTION

[0031] The technical solution of the present application is further illustrated below through specific embodiments. The specific embodiments do not limit the scope of protection of the present application; some non-essential modifications and adjustments made by others based on the concept of the present application still fall within the scope of protection of the present application.

[0032] Unless otherwise specified, the experimental methods described in the following examples are conventional methods. The reagents and materials described are all commercially available products.

[0033] The present application is further described in detail below with reference to the following examples and comparative examples. Example

[0034] Example 1

[0035] A nano-microencapsulated environmentally friendly water- and oil-repellent wax emulsion, the preparation method of which is as follows:

[0036] S1: Carnauba wax modification: Preheat 2 kg of KH570 silane coupling agent to 60°C, add 100 kg of carnauba wax, and stir at 80°C and ≥500 rpm for 30 min to obtain modified wax, which is set aside;

[0037] S2: Compounding and emulsification: 10 kg of polyoxyethylene octadecyl ether was premixed with 24 kg of the first solvent at 70°C, stirred until a transparent solution was obtained, and added to 75 kg of the modified wax prepared in S1. 0.6 kg of emulsifier was then added, and the mixture was stirred at 300 rpm for 200 min while maintaining the temperature at 80°C to obtain a compounded wax emulsion.

[0038] S3: Polymerization: Add 0.5% citric acid to the compound wax emulsion prepared in S2 to adjust the pH to 3.5±0.1, add 866.7g potassium persulfate to 3kg second solvent to dissolve, and add 133.3g sodium bisulfite to 3kg third solvent to dissolve, add them slowly, control the temperature at 40-60℃ to avoid excessive local concentration, add 15L methyl methacrylate monomer after mixing, and react at a pressure of 0.4MPa for 15h to form a nano-encapsulated environmentally friendly water- and oil-repellent wax emulsion.

[0039] Example 2

[0040] A nano-microencapsulated environmentally friendly water- and oil-repellent wax emulsion is prepared, which differs from Example 1 in that the modified wax is carnauba wax and the mass ratio of KH570 silane coupling agent is 40:1, the added amounts are 80 kg of carnauba wax and 2 kg of KH570 silane coupling agent, and the remaining steps and raw material addition amounts are the same as those in Example 1.

[0041] Example 3

[0042] A nano-microencapsulated environmentally friendly water- and oil-repellent wax emulsion is prepared, which differs from Example 1 in that the modified wax is carnauba wax and the mass ratio of KH570 silane coupling agent is 60:1, the added amounts are 120 kg of carnauba wax and 2 kg of KH570 silane coupling agent, and the remaining steps and raw material addition amounts are the same as those in Example 1.

[0043] Example 4

[0044] A nano-microencapsulated environmentally friendly water- and oil-repellent wax emulsion is prepared. The difference from Example 1 is that the amount of modified wax added is 70 kg, and the remaining steps and raw material addition amounts are the same as those in Example 1.

[0045] Example 5

[0046] A nano-microencapsulated environmentally friendly water- and oil-repellent wax emulsion is different from Example 1 in that the amount of modified wax added is 80 kg, and the remaining steps and raw material addition amounts are the same as those in Example 1.

[0047] Example 6

[0048] A nano-microencapsulated environmentally friendly water- and oil-repellent wax emulsion is prepared. The difference from Example 1 is that the amount of methyl methacrylate monomer added is 10 kg, and the remaining steps and raw material addition amounts are the same as those in Example 1.

[0049] Example 7

[0050] A nano-encapsulated environmentally friendly water- and oil-repellent wax emulsion is prepared. The difference from Example 1 is that the amount of methyl methacrylate monomer added is 20 kg, and the remaining steps and raw material addition amounts are the same as those in Example 1.

[0051] Comparative Example

[0052] Comparative Example 1

[0053] A nano-encapsulated environmentally friendly water- and oil-repellent wax emulsion is disclosed, which differs from Example 1 in that the modified wax added to the raw materials is replaced by carnauba wax of equal mass, and the remaining steps and raw material addition amounts are the same as those in Example 1.

[0054] Comparative Example 2

[0055] A nano-microencapsulated environmentally friendly water- and oil-repellent wax emulsion is prepared, which differs from Example 1 in that the emulsifier added to the raw materials is replaced by an equal mass of sodium lauryl sulfate, and the remaining steps and raw material addition amounts are the same as those in Example 1.

[0056] Comparative Example 3

[0057] A nano-microencapsulated environmentally friendly water- and oil-repellent wax emulsion is prepared, which differs from Example 1 in that the emulsifier added to the raw materials is replaced by an equal mass of Tween 80, and the remaining steps and raw material addition amounts are the same as those in Example 1.

[0058] Comparative Example 4

[0059] A nano-microencapsulated environmentally friendly water- and oil-repellent wax emulsion is different from Example 1 in that no emulsifier is added to the raw materials, and deionized water of equal mass is used instead. The remaining steps and the amount of raw materials added are the same as those in Example 1.

[0060] Comparative Example 5

[0061] A nano-microencapsulated environmentally friendly water- and oil-repellent wax emulsion is prepared, which differs from Example 1 in that the S3 nano-microencapsulation step is not performed during the preparation process, and the remaining steps and raw material addition amounts are the same as those in Example 1.

[0062] Performance testing

[0063] Nano-encapsulated, environmentally friendly, water- and oil-repellent wax emulsions were prepared according to the methods described in Examples 1-7 and Comparative Examples 1-5. The nano-encapsulated, environmentally friendly, water- and oil-repellent wax emulsions were then applied to handsheet paper at a coating weight of 7 g / m² and dried with hot air at 120°C. Testing was then performed according to the following method. The test results are shown in Table 1.

[0064] Stability test: No stratification or precipitation when stored at 4-40℃ for 30 days.

[0065] Surface contact angle measurement: The handsheet surface contact angle was measured using a contact angle analyzer. The test liquids were water and castor oil, and the test droplet volume was 4 µL. The contact angle was recorded 30 seconds after the droplet stabilized. The contact angle was used as an indicator of the paper's oil and water repellency. A larger contact angle indicates greater resistance to water / oil penetration and better water / oil repellency.

[0066] Grease Reagent Test Method: In accordance with TAPPI T559 and ISO 16532-1, a mixture of castor oil and n-heptane in varying proportions was used as the grease reagent. The mixture was dropped onto the handsheet surface, left to stand for 15 seconds, and observed for any penetration or wetting. The highest grease reagent number that did not penetrate the surface was used to determine the oil repellency rating, which was categorized as 1-12, with 12 being the highest.

[0067] Biodegradation test: The applied coating is buried in mud with a relative humidity of 50%. After 120 days, the coating is observed to see if it has collapsed by 90% or more. If it has collapsed by 90%, it is biodegradable; otherwise, it is non-degradable.

[0068] Table 1 Test results of Examples 1-7 and Comparative Examples 1-5

[0069] stability Contact angle (°) Oil resistance grade Biodegradation Example 1 No stratification or precipitation 119 Level 11 biodegradable Example 2 No stratification or precipitation 113 Level 10 biodegradable Example 3 No stratification or precipitation 109 Level 9 biodegradable Example 4 No stratification or precipitation 112 Level 10 biodegradable Example 5 No stratification or precipitation 104 Level 9 biodegradable Example 6 No stratification or precipitation 109 Level 10 biodegradable Example 7 No stratification or precipitation 106 Level 10 biodegradable Comparative Example 1 Slight delamination 92 Level 9 biodegradable Comparative Example 2 No stratification or precipitation 102 Level 9 biodegradable Comparative Example 3 Slight delamination 100 Level 9 biodegradable Comparative Example 4 Layering 97 Level 8 biodegradable Comparative Example 5 Slight precipitation 92 Level 8 biodegradable

[0070] As shown in Table 1, the environmentally friendly water- and oil-repellent wax emulsions prepared by the nano-microencapsulation of Examples 1-7 are not stratified or precipitated when stored for 30 days at 4-40°C; the surface contact angle is between 104° and 119°, indicating that the coating has good hydrophobicity; the oil resistance grade is between 9 and 11, indicating that the coating has excellent oil resistance; and the applied coating is buried in a muddy ground with a humidity of 50%. After being buried for 180 days, the degree of collapse of the coating is observed to be ≥90%, and both are biodegradable. Carnauba wax has a high melting point, strong glossiness and biodegradability, and combined with the surface modification effect of a silane coupling agent, it may impart better dispersibility and interfacial bonding. The above experiments can illustrate that the environmentally friendly water- and oil-repellent wax emulsions prepared by the nano-microencapsulation of the present application have the effects of water- and oil-repellent, degradable, high stability, simple process and food contact.

[0071] Compared with the test data of Examples 1-7, the contact angle of Comparative Example 1 is 92° and the oil resistance grade is 9 degrees, which are significantly lower than the test data of Examples 1-7. The carnauba wax is modified using KH570 silane coupling agent, and silicone groups are introduced into the carnauba wax molecules, which significantly improves the hydrophobicity and interfacial properties of the wax.

[0072] Compared with the test data of Examples 1-7, the stability, contact angle and oil resistance grade of Comparative Examples 2-4 are all lower than those of Examples 1-7. Although the amount of emulsifier added in the ratio is small, the synergistic effect of the compounding of polyoxyethylene octadecyl ether and the emulsifier realizes a stable dispersion system of nano-microcapsules, so that the nano-microencapsulated environmentally friendly water- and oil-repellent wax emulsion has good water- and oil-repellency and stability.

[0073] Compared with the test data of Examples 1-7, the stability, contact angle and oil resistance level of Comparative Example 5 are all lower than those of Examples 1-7, indicating that through the nano-microencapsulation technology, the polymerization reaction of methyl methacrylate monomer and compound wax emulsion forms polymethyl methacrylate wall material on the surface of the wax emulsion, which not only obtains the water and oil repellent properties of the wax emulsion, but also enhances its stability.

[0074] The environmentally friendly water-repellent and oil-repellent wax emulsion of nano-microencapsulation prepared by adopting the technical scheme of embodiment 1-7, the raw material composition belongs to aqueous solvent-free system, meets the requirements of GB 33372-2020 "Limit of Volatile Organic Compounds in Adhesives", and reduces the environmental burden during the synthesis process. Meanwhile, modified wax has good hydrophobicity and adhesion to substrate, and polyoxyethylene octadecyl ether and emulsifier are compounded to realize the stable dispersion system of nano-microcapsules; Nano-microencapsulation technology, through the polymerization reaction of methyl methacrylate monomer, forms polymethyl methacrylate wall material on the surface of wax emulsion, realizes the nano-microencapsulation of wax emulsion, not only improves the water-repellent and oil-repellent performance of wax emulsion, but also enhances its stability and durability. Prepare nano-microencapsulated environmentally friendly water-repellent and oil-repellent wax emulsion, with the advantages of water-repellent and oil-repellent, environmental protection, high stability and simple process.

[0075] This specific embodiment is merely an explanation of the present invention and is not intended to limit the present invention. After reading this specification, those skilled in the art may make non-creative modifications to this embodiment as needed. However, as long as they are within the scope of the present invention, they are protected by patent law.

Claims

1. A nano-microencapsulated environmentally friendly water- and oil-repellent wax emulsion, characterized in that: The invention is prepared by comprising the following raw materials in parts by weight: 70-80 parts of modified wax, 7-13 parts of polyoxyethylene octadecyl ether, 0.4-0.8 parts of emulsifier, 10-20 parts of methyl methacrylate monomer, 0.5-1.5 parts of initiator, and 20-40 parts of deionized water. The modified wax is composed of carnauba wax and KH570 silane coupling agent. The emulsifier is any one or more of sodium fatty alcohol polyoxyethylene ether sulfate, sodium starch octenylsuccinate, alkyl glucoside, sucrose ester, lecithin, and cocamidopropyl betaine; The deionized water comprises a first solvent for dissolving polyoxyethylene octadecyl ether, a second solvent for dissolving potassium persulfate, and a third solvent for dissolving sodium bisulfite, wherein the mass ratio of the first solvent, the second solvent, and the third solvent is 8:(1-2):(1-2); The preparation method of the nano-microencapsulated environmentally friendly water- and oil-repellent wax emulsion comprises the following steps: S1: Carnauba wax modification: KH570 silane coupling agent was added to carnauba wax, and the mixture was stirred to obtain modified wax; S2: Compounding and emulsification: premix polyoxyethylene octadecyl ether with a first solvent at 60-70°C, stir until a transparent solution is obtained, add the mixture to the modified wax prepared in S1, and then add an emulsifier and stir to obtain a compounded wax emulsion; S3: Polymerization: Add citric acid to the compound wax emulsion prepared in S2 to adjust the pH value, add initiator, control the temperature at 40-60°C, and add methyl methacrylate monomer to react to form a nano-encapsulated environmentally friendly water- and oil-repellent wax emulsion.

2. The environmentally friendly water- and oil-repellent wax emulsion of nano-microencapsulation according to claim 1, characterized in that The modified wax is carnauba wax and KH570 silane coupling agent in a mass ratio of (40-60):

1.

3. The environmentally friendly water- and oil-repellent wax emulsion of nano-microencapsulation according to claim 1, characterized in that The polyoxyethylene stearyl ether is any one or more of polyoxyethylene (2) stearyl ether and polyoxyethylene (10) stearyl ether.

4. The environmentally friendly water- and oil-repellent wax emulsion of nano-microencapsulation according to claim 1, characterized in that The mass ratio of the initiator, potassium persulfate and sodium bisulfite is (5-8):

1.

5. The environmentally friendly water- and oil-repellent wax emulsion of nano-microencapsulation according to claim 1, characterized in that: In step S1, the carnauba wax is hydrophobically modified by stirring and mixing at 80-100° C. and ≥500 rpm for 20-40 minutes to obtain modified wax.

6. The environmentally friendly water- and oil-repellent wax emulsion of nano-microencapsulation according to claim 1, characterized in that: In step S2, the emulsification reaction is maintained at a temperature of 75-85° C. and stirred at 300-400 rpm for 10-30 min to prepare a composite wax emulsion.

7. The environmentally friendly water- and oil-repellent wax emulsion of nano-microencapsulation according to claim 1, characterized in that: In step S3, the polymerization reaction is carried out at a pressure of 0.2-0.6 MPa for 10-20 hours to form a nano-microencapsulated environmentally friendly water- and oil-repellent wax emulsion.