Fluorine-free oil repellent with dendritic crosslinked structure and preparation method thereof

Abstract

The application discloses a kind of fluorine-free oil-proof agent of dendritic crosslinking structure and preparation method thereof, comprising the following steps: vinyl siloxane monomer, hydrogen-containing siloxane monomer, unsaturated double bond organic monomer copolymerization obtains dendritic structure silicon resin, dendritic structure silicon resin and solvent are mixed to obtain fluorine-free oil-proof agent of dendritic crosslinking structure;The molecular weight of vinyl siloxane monomer is 1000-3000;The molecular weight of hydrogen-containing siloxane monomer is 1000-3000;Unsaturated double bond organic monomer is any one or combination in vinyl aromatic monomer or olefin monomer.The dendritic structure silicon resin of the application has excellent comprehensive performance by unique molecular structure design, combines the advantages of dendritic polymer and silicon resin, has excellent comprehensive performance.High heat resistance enables it to be used stably in high temperature environment.

Description

Technical Field

[0001] This invention belongs to the field of functional materials technology, and in particular relates to a dendritic cross-linked fluorine-free oil repellent and its preparation method. Background Technology

[0002] Smart devices have become indispensable tools in our lives, such as smartphones, watches, headphones, and smart speakers. The acoustic and electrical components inside these devices are very fragile and easily damaged by water, oil, and solid particles (dust, waste, and hazardous debris). The main solution is to add a protective layer at the external openings. This layer typically uses mesh, steel mesh, or thin film materials to ensure breathability while forming a barrier at the openings to effectively isolate dirt and dust. However, the above materials have relatively weak resistance to oil stains, thus requiring oleophobic modification treatment. In fact, to date, all developed superoleophobic coatings use materials with a large amount of CF... 2- and CF 3- Fluorinated compounds with fluoropolymer groups, such as PTFE, perfluorosilanes, and perfluoropolymers. Given the inherent surface tension limitations of the materials, previous highly oleophobic coatings were primarily based on fluorinated materials with surface energy.

[0003] CN118930763A discloses a fluorine-free waterproofing agent, which is prepared using acrylates. It incorporates long-chain alkyl and epoxy active groups to facilitate reaction with surface-active groups on fabrics, enhancing wash resistance and providing a better hand feel. However, its formula, primarily based on acrylates, has high surface tension and is mainly for waterproofing, not oil repellency.

[0004] CN116854888A discloses a method of achieving waterproofing by crosslinking trimethylolpropane with IPDI and diethanolamine to form a dendritic resin. However, the polymer contains a large number of hydrophilic bonds such as formate bonds, ether bonds, hydroxyl bonds, and ionic bonds, resulting in high surface tension. This leads to poor compatibility with PTFE membranes and repulsion between the polymer and the PTFE membrane surface, causing the hydrophilic bonds to align outwards. This increases the overall surface tension of the membrane, affecting its waterproof and oil-resistant properties. Summary of the Invention

[0005] In view of this, the present invention aims to provide a dendritic cross-linked fluorine-free oil repellent and its preparation method, so as to solve at least one technical problem in the background art.

[0006] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0007] A method for preparing a dendritic cross-linked fluorine-free oil repellent includes the following steps: copolymerizing vinyl siloxane monomers, hydrogen-containing siloxane monomers, and unsaturated double-bonded organic monomers to obtain a dendritic silicone resin; mixing the dendritic silicone resin with a solvent to obtain a dendritic cross-linked fluorine-free oil repellent.

[0008] The molecular weight of vinylsiloxane monomers is 1000-3000;

[0009] The molecular weight of hydrogen-containing siloxane monomers is 1000-3000;

[0010] The unsaturated double bond organic monomer is any one or a combination of vinyl aromatic monomers or olefin monomers.

[0011] The vinyl siloxane monomer has the chemical formula Vi-(Me2SiO)m(Vi-MeSiO)nSiMeVi and a vinyl content of 3%.

[0012] The structural formula of the hydrogen-containing silicone oil monomer is Me3SiO(Me2SiO)m(MeHSiO)nSiMe3, and the hydrogen content is 0.5%.

[0013] Furthermore, the olefin monomer is selected from one or more of methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, cyclohexyl acrylate, vinyl acetate, propylene, and butadiene.

[0014] Furthermore, the vinyl aromatic monomer is selected from one or more of styrene, 1-methylvinylbenzene, and divinylbenzene.

[0015] Furthermore, the mass of the hydrogen-containing siloxane monomer is 3%–10% of the total mass of the prepared dendritic silicone resin.

[0016] Furthermore, the mass ratio of vinylsiloxane monomer to unsaturated double-bonded organic monomer is 9-11:1.

[0017] A method for preparing a dendritic cross-linked fluorine-free oil repellent includes the following steps:

[0018] S1: Under inert gas protection, vinylsiloxane monomers, unsaturated double-bonded organic monomers, and initiators are mixed and heated to carry out a polymerization reaction to obtain a mixture; through unsaturated bond addition reaction, branched organic groups are introduced into the siloxane backbone to form a preliminary branched structure.

[0019] S2: Hydrogen-containing siloxane monomers and catalysts are added to the mixture from step S1, and the mixture is heated to initiate a reaction. After the reaction, post-treatment is performed to obtain a dendritic silicone resin. A solvent is then used to prepare a dendritic cross-linked, fluorine-free oil-resistant agent. This reaction introduces more methyl groups at the ends of the dendritic structure, controlling the cross-linking molecular weight and forming a dendritic silicone resin with a certain viscosity.

[0020] Furthermore, the inert gas in step S1 is selected from one or more of nitrogen and argon;

[0021] The initiator in step S1 is selected from one or both of azobisisobutyronitrile and benzoyl peroxide;

[0022] The mass of the initiator is 0.1%–0.5% of the total mass of the vinylsiloxane monomer, the hydrogen-containing siloxane monomer, and the unsaturated double-bonded organic monomer;

[0023] The temperature for the polymerization reaction in step S1 is 50-100℃;

[0024] The time for the polymerization reaction in step S1 is 1-5 hours.

[0025] Furthermore, the catalyst in step S2 is chloroplatinic acid;

[0026] In step S2, the reaction temperature for the hydrogen-containing siloxane monomer and catalyst is 30-50℃, and the reaction time is 3-6h.

[0027] The mass of the catalyst is 0.03%–0.1% of the total mass of vinylsiloxane monomers, hydrogen-containing siloxane monomers, and unsaturated double-bonded organic monomers.

[0028] Furthermore, the post-processing in step S2 includes distilling the reaction product under reduced pressure;

[0029] The dendritic cross-linked fluorine-free oil repellent prepared in step S2 has a dendritic silicone resin mass fraction of 4-10%.

[0030] The above-mentioned method for preparing a dendritic cross-linked fluorine-free oil repellent includes a solvent and a dendritic silicone resin.

[0031] Furthermore, the solvent includes one or more of toluene, xylene, acetone, and trichloropropane.

[0032] Vinylsiloxane monomers are vinyl silicone oils;

[0033] Hydrogen-containing siloxane monomers are hydrogen-containing silicone oils.

[0034] Compared with existing technologies, the dendritic oleophobic agent of this invention has a highly branched dendritic macromolecular structure with silicon atoms as the core, connected by silicon-oxygen bonds. In the molecular structure, a small amount of side-group hydrogen-containing silicone oil is added, which increases both the crosslinking degree of the oleophobic agent and a large number of methyl groups. Vinyl silicone oil serves as the main reactant, resulting in a small amount of crosslinkable groups in the oleophobic agent. The addition of unsaturated double-bonded organic monomers endows the silicone resin with a certain affinity for different substrates, promoting the outward orientation of CH3 groups and enhancing the oleophobic properties of the silicone resin. Simultaneously, it can further participate in chemical reactions, undergoing secondary crosslinking through heating during post-treatment, thereby improving the material's oleophobic performance.

[0035] Compared with existing technologies, the dendritic cross-linked fluorine-free oil repellent and its preparation method described in this invention have the following advantages:

[0036] 1. The dendritic silicone resin of this invention combines the advantages of dendritic polymers and silicone resins through a unique molecular structure design, resulting in excellent comprehensive performance. Its high heat resistance enables stable use in high-temperature environments; its good flexibility and high mechanical strength provide better adaptability in various application scenarios; and its low surface tension and good adhesion to various substrates allow for wide application in the surface treatment of various materials.

[0037] 2. The preparation method of this invention is simple and easy to operate, with mild reaction conditions. It does not require special equipment or complex process steps, making it suitable for large-scale industrial production. Furthermore, by precisely controlling the reaction conditions, the molecular structure and properties of the dendritic silicone resin can be accurately controlled, ensuring the stability and consistency of product quality. Attached Figure Description

[0038] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0039] Figure 1 This is a schematic diagram showing the contact angle changes of the dendritic cross-linked fluorine-free oil repellent prepared in Example 1 of the present invention (a is the contact angle of water on the material without the dendritic cross-linked fluorine-free oil repellent, which is 64.1°; b is the contact angle of water on the material with the dendritic cross-linked fluorine-free oil repellent prepared in the example, which is 124.6°; c is the contact angle of olive oil on the material without the dendritic cross-linked fluorine-free oil repellent prepared in the example, which is 0°; d is the contact angle of olive oil on the material with the dendritic cross-linked fluorine-free oil repellent prepared in the example, which is 90.2°).

[0040] Figure 2Schematic diagrams showing the effects of propylene glycol on blank PP film, the effects of propylene glycol on PP film treated in Example 1, the effects of glycerin on blank PP film, the effects of glycerin on PP film treated in Example 1, the effects of soapy water on blank PP film, and the effects of soapy water on PP film treated in Example 1 (A: effect of propylene glycol on blank PP film, contact angle 45.42°; B: effect of propylene glycol on PP film treated in Example 1, contact angle 48.375°; C: effect of glycerin on blank PP film, contact angle 64.474°; D: effect of glycerin on PP film treated in Example 1, contact angle 100.675°; E: effect of soapy water on blank PP film, contact angle 102.764°; F: effect of soapy water on PP film treated in Example 1, contact angle 118.542°).

[0041] Figure 3 This is a spectral analysis diagram of the dendritic cross-linked fluorine-free oil repellent of Example 1 of this application. Detailed Implementation

[0042] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0043] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0044] The hydrogen-containing silicone oil was purchased from Dow Corning (Zhangjiagang) Organosilicon Co., Ltd.

[0045] The vinyl silicone oil was purchased from Shenzhen Jipeng Silicon Fluorine Materials Co., Ltd.

[0046] Example 1:

[0047] Step 1: Under nitrogen protection, add 150g of vinyl silicone oil (vinyl siloxane monomer, structural formula Vi-(Me2SiO)m(Vi-MeSiO)nSiMeVi, vinyl content 3%), molecular weight 1000, 15g of styrene, and 0.5g of azobisisobutyronitrile to a reactor equipped with a stirrer, thermometer, and reflux condenser. Heat to 70℃ and react for 5 hours.

[0048] Step 2: Add 8g of hydrogen-containing silicone oil (the structural formula of the hydrogen-containing silicone oil monomer is Me3SiO(Me2SiO)m(MeHSiO)nSiMe3, with a hydrogen content of 0.5%), a molecular weight of 1000, a Si-H content of 1.5mmol / g, and 0.1g of chloroplatinic acid catalyst to the above reaction system, control the temperature at 40℃ and react for 4 hours.

[0049] Step 3: After the reaction is complete, the reaction product is subjected to vacuum distillation to remove solvent and unreacted monomers and other small molecule impurities to obtain dendritic silicone resin. Then, 5 grams of the obtained dendritic silicone resin is taken and 95 grams of trichloropropane are added to prepare a 5% (w / w) solution of dendritic silicone resin to obtain a dendritic cross-linked fluorine-free oil repellent.

[0050] The contact angle change of the dendritic cross-linked non-fluorinated oil repellent prepared in Example 1 (e.g., the coating angle of the oil repellent). Figure 1 As shown, a represents the contact angle of water on the material without the dendritic cross-linked fluorine-free oil repellent coating, which is 64.1°; b represents the contact angle of water on the material coated with the dendritic cross-linked fluorine-free oil repellent prepared in the example, which is 124.6°; c represents the contact angle of olive oil on the material without the dendritic cross-linked fluorine-free oil repellent coating, which is 0°; and d represents the contact angle of olive oil on the material coated with the dendritic cross-linked fluorine-free oil repellent prepared in the example, which is 90.2°. Figure 2 The diagrams show the effects of propylene glycol on the blank PP film, the propylene glycol effect on the PP film treated in Example 1, the glycerin effect on the blank PP film, the glycerin effect on the PP film treated in Example 1, the soap solution effect on the blank PP film, and the soap solution effect on the PP film treated in Example 1. In these diagrams, A represents the effect of propylene glycol on the blank PP film with a contact angle of 45.42°; B represents the effect of propylene glycol on the PP film treated in Example 1 with a contact angle of 48.375°; C represents the effect of glycerin on the blank PP film with a contact angle of 64.474°; D represents the effect of glycerin on the PP film treated in Example 1 with a contact angle of 100.675°; E represents the effect of soap solution on the blank PP film with a contact angle of 102.764°; and F represents the effect of soap solution on the PP film treated in Example 1 with a contact angle of 118.542°.

[0051] like Figure 3 As shown, 3081cm -1 2949cm -1 2923cm -1 The absorption peak is the stretching vibration of the benzene ring, at 2173 cm⁻¹. -1 The absorption peak is the stretching vibration of the hydrogen-containing (-Si—H) bond, at 1131 cm⁻¹. -1 and 1093cm -1 The absorption peak is due to the bending vibration of -Si-OC. Infrared analysis confirmed that vinylsiloxane reacts with hydrogen-containing siloxanes and styrene to form a dendritic structure, with a peak at 2173 cm⁻¹. -1 The stretching vibration absorption peak of the hydrogen-containing (-Si—H) bond disappears, while the absorption peak at 3081 cm⁻¹ disappears. -1 2949cm -1 2923cm -1 It exhibits a strong absorption peak, and the vinylsiloxane reacts with the hydrogen-containing siloxane, while styrene is successfully attached to the dendritic molecular chain.

[0052] Example 2:

[0053] Step 1: Under argon protection, add 150g of vinyl silicone oil (vinyl siloxane monomer, structural formula Vi-(Me2SiO)m(Vi-MeSiO)nSiMeVi, vinyl content 3%), 50g of styrene, and 0.5g of azobisisobutyronitrile to a reactor equipped with a stirrer, thermometer, and reflux condenser. Heat to 70℃ and react for 5 hours.

[0054] Step 2: Add 5g of hydrogen-containing silicone oil (the structural formula of the hydrogen-containing silicone oil monomer is Me3SiO(Me2SiO)m(MeHSiO)nSiMe3, with a hydrogen content of 0.5%), a molecular weight of 1000, a Si-H content of 1.5mmol / g, and 0.1g of chloroplatinic acid catalyst to the above reaction system. Control the temperature at 40℃ and carry out the reaction for 3-6 hours.

[0055] After the reaction was completed, the reaction product was subjected to vacuum distillation to remove solvent and unreacted monomers and other small molecule impurities to obtain a dendritic silicone resin. Then, 5 grams of the obtained dendritic silicone resin was taken and 95 grams of trichloropropane were added to prepare a 5% (w / w) solution of the dendritic silicone resin, thus obtaining a dendritic cross-linked fluorine-free oil repellent.

[0056] Example 3:

[0057] Step 1: Under nitrogen protection, add 150g of vinyl silicone oil (vinyl siloxane monomer, structural formula Vi-(Me2SiO)m(Vi-MeSiO)nSiMeVi, vinyl content 3%), 15g of butyl acrylate, and 0.5g of azobisisobutyronitrile to a reactor equipped with a stirrer, thermometer, and reflux condenser. Heat to 70℃ and react for 5 hours.

[0058] Step 2: Add 16g of hydrogen-containing silicone oil (the structural formula of the hydrogen-containing silicone oil monomer is Me3SiO(Me2SiO)m(MeHSiO)nSiMe3, with a hydrogen content of 0.5%), a molecular weight of 1000, a Si-H content of 1.5mmol / g, and 0.1g of chloroplatinic acid catalyst to the above reaction system. Control the temperature at 40℃ and carry out the reaction for 3-6 hours.

[0059] Step 3: After the reaction is complete, the reaction product is subjected to vacuum distillation to remove solvent and unreacted monomers and other small molecule impurities to obtain dendritic silicone resin. Then, 5 grams of the obtained dendritic silicone resin is taken and 95 grams of trichloropropane are added to prepare a 5% (w / w) solution of dendritic silicone resin to obtain a dendritic cross-linked fluorine-free oil repellent.

[0060] Example 4:

[0061] Step 1: Under nitrogen protection, add 150g of vinyl silicone oil (vinyl siloxane monomer, structural formula Vi-(Me2SiO)m(Vi-MeSiO)nSiMeVi, vinyl content 3%), 15g of styrene, and 0.5g of azobisisobutyronitrile to a reactor equipped with a stirrer, thermometer, and reflux condenser. Heat to 70℃ and react for 5 hours.

[0062] Step 2: Add 8g of hydrogen-containing silicone oil (the structural formula of the hydrogen-containing silicone oil monomer is Me3SiO(Me2SiO)m(MeHSiO)nSiMe3, the hydrogen content is 0.5%, the molecular weight is 3000, and the Si-H content is 1.5mmol / g) and 0.05g of chloroplatinic acid catalyst to the above reaction system, control the temperature at 40℃ and react for 3-6 hours.

[0063] Step 3: After the reaction is complete, the reaction product is subjected to vacuum distillation to remove solvent and unreacted monomers and other small molecule impurities to obtain dendritic silicone resin. Then, 5 grams of the obtained dendritic silicone resin is taken and 95 grams of trichloropropane are added to prepare a 5% (w / w) solution of dendritic silicone resin to obtain a dendritic cross-linked fluorine-free oil repellent.

[0064] Example 5:

[0065] Step 1: Under nitrogen protection, add 150g of vinyl silicone oil (vinyl siloxane monomer, structural formula Vi-(Me2SiO)m(Vi-MeSiO)nSiMeVi, vinyl content 3%), 15g of butyl acrylate, and 0.738g of benzoyl peroxide to a reactor equipped with a stirrer, thermometer, and reflux condenser. Heat to 70℃ and react for 5 hours.

[0066] Step 2: Add 8g of hydrogen-containing silicone oil (the structural formula of the hydrogen-containing silicone oil monomer is Me3SiO(Me2SiO)m(MeHSiO)nSiMe3, with a hydrogen content of 0.5%), a molecular weight of 1000, a Si-H content of 1.5mmol / g, and 0.1g of chloroplatinic acid catalyst to the above reaction system, control the temperature at 40℃ and react for 4 hours.

[0067] Step 3: After the reaction is complete, the reaction product is subjected to vacuum distillation to remove solvent and unreacted monomers and other small molecule impurities to obtain dendritic silicone resin. Then, 5 grams of the obtained dendritic silicone resin is taken and 95 grams of trichloropropane are added to prepare a 5% (w / w) solution of dendritic silicone resin to obtain a dendritic cross-linked fluorine-free oil repellent.

[0068] Comparative Example 1:

[0069] Purchase commercially available ordinary silicone resin, model RSN-0749.

[0070] Comparative Example 2:

[0071] The difference from Example 1 is that the molecular weight of the vinyl silicone oil was changed to 10,000, while other reaction conditions remained unchanged to prepare a dendritic silicone resin. In this case, agglomeration occurred, and a stable solution could not be formed.

[0072] Comparative Example 3

[0073] The difference from Example 1 is that the molecular weight of the hydrogen-containing silicone oil is 5000. When the reaction conditions are unchanged to prepare the dendritic silicone resin, agglomeration occurs and a stable solution cannot be formed.

[0074] Comparative Example 4

[0075] The difference from Example 1 is that the molecular weight of the vinyl silicone oil is 800;

[0076] The molecular weight of hydrogen-containing silicone oil is 1000;

[0077] Compared to Example 1, the degree of crosslinking is low and the oleophobic properties of the reaction product are poor.

[0078] Comparative Example 5

[0079] The difference from Example 1 is that the molecular weight of the vinyl silicone oil is 4000;

[0080] The molecular weight of hydrogen-containing silicone oil is 1000;

[0081] Excessive cross-linking in the reaction results in a product with high viscosity, making it difficult to dissolve and form a homogeneous solution. Consequently, uneven oleophobic properties occur during the oleophobic treatment of PTEF membranes.

[0082] Comparative Example 6

[0083] The difference from Example 1 is that the molecular weight of the vinyl silicone oil is 1000;

[0084] The molecular weight of hydrogen-containing silicone oil is 4000;

[0085] Increased cross-linking degree makes the reaction difficult to control, easily leads to agglomeration, and results in uneven membrane performance.

[0086] Comparative Example 7

[0087] The difference from Example 1 is that the molecular weight of the vinyl silicone oil is 1000;

[0088] The molecular weight of hydrogen-containing silicone oil is 800;

[0089] The degree of cross-linking is extremely low, and the product has no oleophobic properties.

[0090] Performance testing

[0091] 1. Waterproof and oil-proof test:

[0092] Sample preparation: A certain amount of samples from Examples 1 to 5 and Comparative Examples 1 to 7 were coated onto PTFE films. After coating, the samples were heated and cured at 100°C for 30 minutes.

[0093] Test method:

[0094] 1) Immerse the sample sheet (both sides of the inner pore membrane can be in contact with the solution) in water, hand soap, shampoo, and vegetable oil;

[0095] 2) After soaking for 10 hours, samples were taken to inspect appearance and function. Table 1 shows schematic diagrams of the effects of different batches A, B, and C in Examples 1-5 and Comparative Examples 1-7, respectively.

[0096] Table 1 shows the effects of different batches A, B, and C in Examples 1-5 and Comparative Examples 1-7, respectively. ;

[0097] Water droplet angle and oil droplet angle tests:

[0098] The sample for the droplet angle test was a PP film. The test condition was the instantaneous droplet angle. The test method used a JC2000D5 contact angle tester. Before the experiment, the injection needle was thoroughly wetted with deionized water or n-hexadecane, and the presence of air bubbles in the syringe was observed during the injection process. Water or oil was dripped onto the substrate surface with the syringe. After the droplet stabilized, the contact angle formed by the droplet was recorded by taking a picture with the instrument. To ensure the accuracy of the test, 3-5 points were measured for each coating, and the average value was calculated, as shown in Table 2.

[0099] Table 2 shows the effects of water, propylene glycol, olive oil, and n-hexadecane on Examples 1-5 and Comparative Examples 1-7.

[0100] ;

[0101] The larger the contact angle, the closer the droplet is to a perfect sphere, indicating a weaker interaction between the liquid and the surface, and a better surface hydrophobicity / liquid resistance.

[0102] The original PP breathable membrane (untreated) has a 70° contact angle with water (some hydrophobicity), but a 0° contact angle with all organic liquids (propylene glycol, olive oil, n-hexadecane) (complete wetting), indicating complete oleophilicity and no oil-repellent properties. This is a typical characteristic of low surface energy polyolefin materials, where the surface energy is higher than the surface tension of organic liquids.

[0103] Examples 1, 3, 4, and 5 have a water contact angle >125°, meeting the superhydrophobic standard. Example 2 has excellent waterproof (114°) and propylene glycol (100°) properties, but is completely wetted by olive oil and n-hexadecane (0°). This treatment only improves the material's protection against liquids with moderate surface tension.

[0104] Comparative Examples 2, 3, 4, and 7 show that the contact angle data for all liquids are completely consistent with those for the untreated PP film. These treatment processes were completely ineffective and failed to change the surface chemistry or morphology of the PP film.

[0105] Comparative Examples 1 and 5 exhibit only moderate hydrophobicity (water contact angle 100°), completely wetting all organic liquids. The treatment process only slightly improves water resistance, falling far short of superhydrophobicity and failing to impart any oil resistance. It may simply introduce some roughness or weak hydrophobic groups, but this is insufficient to resist organic liquids.

[0106] Comparative Example 6 has superhydrophobic (125°) properties and is resistant to olive oil (115°), but is wetted by propylene glycol and n-hexadecane.

[0107] 3. Temperature resistance test;

[0108] Test method: PI films treated with the fluorine-free oil-resistant agents prepared in Examples 1-5 and blank PI films were placed in an oven and heated at 300°C for 30 minutes.

[0109] 1) Observe the wetting condition using propylene glycol test;

[0110] 2) Test for weightlessness;

[0111] Table 3. Weightlessness in Examples 1-5;

[0112] sample Unheated wettability Add 30 minutes of wetting Weightlessness after heating Example 1 Non-wetting Non-wetting 0 Example 2 infiltration infiltration 0 Example 3 Non-wetting Non-wetting 0 Example 4 Non-wetting Non-wetting 0 Example 5 Non-wetting Non-wetting 0 Blank PI film infiltration infiltration 0

[0113] The PI film did not lose its oleophobic properties after being heated at 300℃ for 30 minutes. The PI film treated with the fluorine-free oleophobic agent did not lose weight or become non-wetted after being heated at 300℃ for 30 minutes, indicating that the fluorine-free oleophobic agent is stable at 300℃.

[0114] Through the comparison of the above embodiments and comparative examples, it can be clearly seen that the dendritic structure silicone resin of the present invention has significant advantages in performance. Its preparation method is simple and feasible, and its application effect is good, with broad application prospects and market value.

[0115] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a dendritic cross-linked fluorine-free oil repellent, characterized in that: Includes the following steps: S1: Under inert gas protection, vinylsiloxane monomer, unsaturated double bond organic monomer and initiator are mixed and heated to carry out polymerization reaction to obtain a mixture; S2: Add hydrogen-containing siloxane monomer and catalyst to the mixture in step S1 and heat to react. After the reaction is completed, perform post-treatment to obtain dendritic silicone resin and use solvent to prepare dendritic cross-linked structure fluorine-free oil repellent. The molecular weight of vinylsiloxane monomers is 1000-3000; The molecular weight of hydrogen-containing siloxane monomers is 1000-3000; The unsaturated double-bonded organic monomer is any one or a combination of vinyl aromatic monomers or olefinic monomers; The mass of the hydrogen-containing siloxane monomer is 3%–10% of the total mass of the prepared dendritic silicone resin.

2. The method for preparing a dendritic cross-linked fluorine-free oil repellent according to claim 1, characterized in that: The olefin monomers are selected from one or more of methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, cyclohexyl acrylate, vinyl acetate, propylene, and butadiene.

3. The method for preparing a dendritic cross-linked fluorine-free oil repellent according to claim 1, characterized in that: The vinyl aromatic monomers are selected from one or more of styrene, 1-methylvinylbenzene, and divinylbenzene.

4. The method for preparing a dendritic cross-linked fluorine-free oil repellent according to claim 1, characterized in that: The mass ratio of vinylsiloxane monomer to unsaturated double-bonded organic monomer is 9-11:

1.

5. The method for preparing a dendritic cross-linked fluorine-free oil repellent according to claim 1, characterized in that: The inert gas in step S1 is selected from one or more of nitrogen and argon; The initiator in step S1 is selected from one or both of azobisisobutyronitrile and benzoyl peroxide; The mass of the initiator is 0.1%–0.5% of the total mass of the vinylsiloxane monomer, the hydrogen-containing siloxane monomer, and the unsaturated double-bonded organic monomer; The temperature for the polymerization reaction in step S1 is 50-100℃; The time for the polymerization reaction in step S1 is 1-5 hours.

6. The method for preparing a dendritic cross-linked fluorine-free oil repellent according to claim 1, characterized in that: The catalyst in step S2 is chloroplatinic acid; In step S2, the reaction temperature for the hydrogen-containing siloxane monomer and catalyst is 30-50℃, and the reaction time is 3-6h. The mass of the catalyst is 0.03%–0.1% of the total mass of vinylsiloxane monomers, hydrogen-containing siloxane monomers, and unsaturated double-bonded organic monomers.

7. The method for preparing a dendritic cross-linked fluorine-free oil repellent according to claim 1, characterized in that: The post-processing in step S2 includes distilling the reaction product under reduced pressure. The dendritic cross-linked fluorine-free oil repellent prepared in step S2 has a dendritic silicone resin mass fraction of 4-10%.

8. A dendritic cross-linked fluorine-free oil repellent prepared by the method according to any one of claims 1-7, characterized in that: Dendritic cross-linked fluorine-free oil repellents include solvents and dendritic silicone resins.

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