Fluorine-free oil repellent, preparation method and application thereof

Abstract

The application provides a fluorine-free oil repellent as well as a preparation method and application thereof, and belongs to the technical field of textile auxiliaries. The fluorine-free oil repellent is prepared by reacting a fluorine-free oil-repellent monomer with hydrophobic silica aerogel particles, the fluorine-free oil-repellent monomer has an umbrella-like liquid-like feature, and the hydrophobic silica aerogel particles have a three-dimensional porous network structure. The fluorine-free oil repellent can give the fabric good oil-proof effect.

Description

Technical Field

[0001] This application relates to a fluorine-free oil repellent, its preparation method, and its application, belonging to the field of textile auxiliaries technology. Background Technology

[0002] For a long time, fluorinated finishing agents based on perfluorinated / polyfluoroalkyl structures have been widely used in textiles, leather, papermaking, and medical fields due to their excellent water and oil repellency properties. However, the processing and use of traditional fluorinated water and oil repellent agents often involve the emission of toxic and harmful compounds, posing a significant threat to human health and the environment. The European Union and parts of North America are expected to completely ban the production and use of fluorinated water and oil repellent agents starting in 2025. In 2023, my country also explicitly included perfluorooctanoic acid, perfluorooctyl sulfonic acid, and perfluorohexyl sulfonic acid compounds in the "List of Key New Pollutants under Control".

[0003] Because non-fluorinated substances often have high surface energy, most commercially available fluorine-free waterproofing agents currently lack oil-repellent properties. Research on fluorine-free oil-repellent agents for textiles is still in its early stages. In her paper "Non-fluorine oilrepellency: to what extent can it substitute perfluoroalkyl substances," Zhao Yan used chemical vapor deposition (CVD) to covalently graft polydimethylsiloxane (PDMS) molecular brushes onto the surface of nylon fibers. This can, to some extent, prevent the diffusion and penetration of low-surface-energy droplets such as edible oils and hexadecane into the fabric. However, CVD technology cannot be applied on a large scale and at low cost in the textile industry. Zhuang Qixin, in his paper "Fluorine-free low surface energy organiccoating for anti-stain applications," reported that depositing acrylate polymers on the fiber surface and introducing tris(trimethylsiloxane)silyl groups can impart a certain degree of oil-repellent effect to textile materials.

[0004] Furthermore, the microstructure of a surface has a significant impact on surface wettability. Doris Vollmer, in her paper "Fluorine-free super-liquid-repellent surfaces: pushing the limits of PDMS," reported the use of PDMS-modified nanospheres to construct a binary porous microstructure with roughness, resulting in a fluorine-free superhydrophobic surface. Zhao Kai introduced cage-like polysilsesquioxanes into the molecular design of a fluorine-free oil-repellent agent, thereby constructing a nanoscale rough structure on the fiber surface. The treated fabric exhibited a certain degree of oil repellency.

[0005] However, none of the above products can achieve the ideal oil-repellent effect. In particular, the current research results cannot meet the industry's needs for oil-repellent effect and defluorination for waterproof and oil-repellent agents used in the textile industry. Therefore, it is imperative to research and develop fluorine-free oil-repellent agents with better oil-repellent effect. Summary of the Invention

[0006] In view of this, this application firstly provides a fluorine-free oil repellent agent, which not only achieves a fluorine-free chemical composition, but also endows the finished fabric with good oil repellency.

[0007] Specifically, this application is implemented through the following scheme: A fluorine-free oil repellent agent is prepared by reacting a fluorine-free oleophobic monomer with hydrophobic silica aerogel particles, wherein the fluorine-free oleophobic monomer has umbrella-shaped liquid-like characteristics and the hydrophobic silica aerogel particles have a three-dimensional porous network structure.

[0008] The aforementioned fluorine-free oil repellent not only does not introduce fluorine components, but is also endowed with fluorine-free monomers with umbrella-like liquid properties and silica aerogel particles with a three-dimensional network structure. Its umbrella-like liquid properties can effectively prevent common edible oils from penetrating into fabrics, while the three-dimensional network structure can create a rough structure on the fiber surface, thereby further improving the oil-repellent effect of the fluorine-free oil repellent.

[0009] Furthermore, as a preferred option: The fluorine-free oleophobic monomer is a methacryloyloxypropyl T-structure polysiloxane or a methacryloyloxypropyl-functionalized polydimethylsiloxane.

[0010] The hydrophobic silica aerogel particles possess a three-dimensional porous network structure and have methacryloxypropyl or acryloxypropyl groups on their surface. They can be prepared via a two-step acid-base catalytic sol-gel method. Specifically, the hydrophobic silica aerogel particles are prepared as follows: Under stirring conditions, methyltrimethoxysilane and γ-methacryloxypropyltrimethoxysilane are added to methanol. Oxalic acid is then slowly added to the solution while stirring continues. Ammonia is then added dropwise, the reaction vessel is sealed, and gelation is performed. After gelation, a small amount of methanol is added to the reaction vessel as a mother liquor for further aging. Finally, the mixture is pulverized and dried with supercritical carbon dioxide fluid to obtain silica aerogel particles with a three-dimensional porous network structure.

[0011] The applicant's second objective is to provide a method for preparing a fluorine-free oil repellent using a fine emulsion polymerization method, with the following steps: Step 1: Weigh the cationic emulsifier and the nonionic emulsifier, stir them evenly, dissolve them in deionized water, and adjust the pH of the solution to 3-6 to obtain an emulsifier aqueous solution; Step 2: Weigh out the fluorine-free oil-resistant monomer with an umbrella-like liquid structure, the silica aerogel particles with a three-dimensional porous network structure, and the functional monomer, respectively. Disperse the three in a co-solvent, and slowly add the resulting dispersion to the emulsifier aqueous solution to obtain a mixed dispersion. Step 3: First, disperse the mixed dispersion to obtain a crude emulsion, then sonicate the crude emulsion to obtain a fine emulsion, then add the initiator that has been dissolved in deionized water in advance, heat to 70 °C, stir and react for 5 to 20 h, filter the liquid to obtain a fluorine-free oil inhibitor; The mass percentages of the above-mentioned materials added are as follows: Fluorine-free oleophobic monomers: 20-50%, Hydrophobic silica aerogel particles: 2~5%, Functional monomers 0.5-4%, Cosolvent 0-2%, Cationic emulsifiers and nonionic emulsifiers: 2-5%, Initiator: 0.002–1% Deionized water: 40-70%.

[0012] In the above preparation process, the fluorine-free oleophobic monomers exhibit umbrella-like liquid-like characteristics, including methacryloyloxypropyl T-structured polysiloxanes or methacryloyloxypropyl-functionalized polydimethylsiloxanes. Using these monomers can form a large number of umbrella-like liquid-like PDMS segments on the fiber surface, while simultaneously reducing the fiber surface free energy by utilizing the high methyl content of the monomers. The hydrophobic silica aerogel particles possess a three-dimensional porous network structure and have numerous methacryloyloxypropyl or acryloyloxypropyl groups on their surface. The purpose of adding hydrophobic silica aerogel particles is primarily to construct a rough structure on the fiber surface, thereby enhancing the oil-repellent effect of the oil repellent.

[0013] Preferred: The functional monomer contains copolymerizable methacrylate or acrylate groups. More preferably, the functional monomer also contains at least one functional group selected from epoxy, hydroxyl, amino, carboxyl, or ketone carbonyltrialkoxysilyl groups. The functional monomer is a functional monomer that contains both copolymerizable methacrylate or acrylate groups and reactive groups such as epoxy, hydroxyl, amino, carboxyl, or ketone carbonyltrialkoxysilyl groups. Examples include glycidyl methacrylate, hydroxyethyl methacrylate, methacrylic acid, methacrylamide, and N-vinylpyrrolidone. The addition of functional monomers increases the bonding strength between the fluorine-free oil repellent and the textile material, improving the fluorine-free oil repellency durability of the fabric.

[0014] The cationic emulsifier is any one or a mixture of one or more of octadecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, and hexadecyltrimethylammonium chloride.

[0015] The nonionic emulsifier is any one or a mixture of more than one of fatty alcohol polyoxyethylene ether, isomeric alcohol polyoxyethylene ether, Span-80, and polyethylene glycol monolaurate.

[0016] The pH value is adjusted using a pH adjuster, with an addition amount of 0-1.5%, and glacial acetic acid is preferred as the pH adjuster.

[0017] The initiator is any one or a mixture of more than one of azobisisobutyramidine hydrochloride (2,2'-azobisisobutyramidine hydrochloride), azobisisobutyramidine imidazoline hydrochloride, dimethyl azobisisobutyrate, potassium persulfate, and azobisisobutyronitrile.

[0018] The applicant's third objective is to provide an application of the aforementioned fluorine-free oil repellent for use in textile finishing.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) Most of the fluorine-free waterproofing agents on the market do not have oil-repellent function. This invention uses fluorine-free oil-repellent monomers with umbrella-like liquid structure to prepare fluorine-free oil-repellent agents, which can give textiles a better oil-repellent effect.

[0020] (2) The fluorine-free oil repellent in this invention contains silica aerogel particles with a three-dimensional porous network structure, which can build a rough structure at the micro-nano level on the fiber surface, giving textiles a better oil repellent effect.

[0021] (3) The method for preparing the fluorine-free oil repellent provided by the present invention is simple, easy to implement and control, and conducive to promotion and application.

[0022] (4) With this fluorine-free oil repellent, textiles can achieve ideal fluorine-free oil repellency through a simple impregnation-rolling-baking process, and it has broad application prospects in the field of waterproof and oil-proof textile processing. Attached Figure Description

[0023] Figure 1 The silica aerogel particles in this application have a three-dimensional porous network structure; Figure 2 This is a comparison diagram of the oil-repellent effect of the fabric before and after finishing in Example 2 of this application. Detailed Implementation

[0024] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0025] Unless otherwise specified, all products are commercially available conventional preparations.

[0026] Example 1

[0027] This embodiment describes a fluorine-free oil repellent, which is prepared using the following method: Step 1: Under stirring conditions, 80 mL of methyltrimethoxysilane and 40 mL of γ-methacryloxypropyltrimethoxysilane were added to 685 mL of methanol. Then, 50 mL of oxalic acid (0.01 M) was slowly added to the solution while stirring for 24 h. Subsequently, 50 mL of ammonia water (10 M) was added dropwise to the solution while stirring. The reaction vessel was sealed and placed at 50 °C for gelation. After gelation, a small amount of methanol was added to the reaction vessel as a mother liquor for aging treatment for 48 h. Finally, the silica gel was pulverized using a homogenizer and ultrasonic centrifuge. After drying with supercritical carbon dioxide fluid, silica aerogel particles with a three-dimensional porous network structure were obtained, as shown in the figure. Figure 1 As shown.

[0028] Step 2: Weigh 3 g of cationic emulsifier octadecyltrimethylammonium chloride and 18 g of nonionic emulsifier fatty alcohol polyoxyethylene ether, stir them evenly and dissolve them in 460 g of deionized water, and add glacial acetic acid to adjust the pH to around 4 to obtain the emulsifier solution.

[0029] Step 3: Weigh 220 g of methacryloxypropyl-functionalized polydimethylsiloxane (MCS-M11, Gelest, USA), 25 g of silica aerogel particles prepared in Step 1, and 20 g of hydroxyethyl methacrylate and disperse them in 70 g of tripropylene glycol. Slowly add the resulting dispersion to the emulsifier solution prepared in Step 2 to obtain a mixed dispersion.

[0030] Step 4: The mixed dispersion is dispersed using a disperser to obtain a crude emulsion. The crude emulsion is then sonicated in a cell disruptor to obtain a fine emulsion. An aqueous solution containing 2.5 g of initiator 2,2'-azobisisobutyramidine hydrochloride is then added, the temperature is raised to 70 °C, and the mixture is stirred for 8 h. The emulsion is then filtered to obtain a fluorine-free oil repellent in the form of an emulsion.

[0031] Comparative Example 1

[0032] The setup of this comparative example is the same as that of Example 1, except that silica aerogel particles with a three-dimensional porous network structure were not added.

[0033] Comparative Example 2

[0034] The setup for this comparative example is the same as that for Example 1, except that 220 g of methacryloyloxypropyl-functionalized polydimethylsiloxane is replaced with 230 g of octadecyl methacrylate.

[0035] Comparative Example 3

[0036] The setup for this comparative example is the same as that for Example 1, except that 20 g of hydroxyethyl methacrylate was not added.

[0037] Example 2

[0038] This embodiment describes a fluorine-free oil repellent, which is prepared using the following method: Step 1: Under stirring conditions, 80 mL of methyltrimethoxysilane and 40 mL of γ-methacryloxypropyltrimethoxysilane were added to 685 mL of methanol. Then, 50 mL of oxalic acid (0.01 M) was slowly added to the above solution while stirring for 24 h. Subsequently, 50 mL of ammonia water (10 M) was added dropwise to the above solution while stirring. The reaction vessel was then sealed and placed at 50 °C for gelation treatment. After gelation, a small amount of methanol was added to the reaction vessel as a mother liquor for aging treatment for another 48 h. Finally, the silica gel was pulverized using a homogenizer and an ultrasonic centrifuge. After drying with supercritical carbon dioxide fluid, silica aerogel particles with a three-dimensional porous network structure were obtained.

[0039] Step 2: Weigh 3 g of cationic emulsifier octadecyltrimethylammonium chloride and 18 g of nonionic emulsifier fatty alcohol polyoxyethylene ether, stir them evenly and dissolve them in 460 g of deionized water, and add glacial acetic acid to adjust the pH to around 4 to obtain the emulsifier solution.

[0040] Step 3: Weigh 250 g of methacryloyloxypropyl T-structure polysiloxane (RTT-1011, Gelest, USA), 25 g of silica aerogel particles prepared in Step 1, and 25 g of glycidyl methacrylate and disperse them in tripropylene glycol. Slowly add the resulting dispersion to the emulsifier solution to obtain a mixed dispersion.

[0041] Step 4: The mixed emulsion is dispersed using a disperser to obtain a crude emulsion. The crude emulsion is then sonicated in a cell disruptor to obtain a fine emulsion. An aqueous solution containing 2.5 g of initiator 2,2'-azobisisobutyramidine hydrochloride is then added, the temperature is raised to 70 °C, and the mixture is stirred for 8 h. The emulsion is then filtered to obtain a fluorine-free oil repellent in the form of an emulsion.

[0042] Comparative Example 4

[0043] The setup for this comparative example is the same as that for Example 2, except that silica aerogel particles with a three-dimensional porous network structure were not added.

[0044] Comparative Example 5

[0045] The setup for this comparative example is the same as that for Example 2, except that 25 g of glycidyl methacrylate was not added.

[0046] The oil-repellent agents prepared in Examples 1 and 2 and Comparative Examples 1, 2, 3, 4, and 5 were used for fluorine-free oil-repellent finishing of fabrics.

[0047] The oil-resistant finishing process is as follows: Prepare a finishing solution with a solid content of 30% oil repellent to a concentration of 50 g / L, and add 20 g / L of commercially available crosslinking agent (HYDROSIN C-20, Maflon SPA, Italy). Select plain cotton fabric, use a one-dip-one-nip method, and dry at 180 ℃ for 2 min.

[0048] Oil droplet contact angle: Place 5μL of household olive oil droplets on the fabric surface and measure the oil droplet contact angle of the fabric before and after treatment using a contact angle tester. Repeat the test in 5 different areas of the fabric and take the average value of the oil droplet contact angle of the 5 areas as the oil droplet contact angle of the fabric.

[0049] Oil-resistant time: Place 5 microliters of household olive oil on the surface of the fabric and observe the time it takes for the oil droplet to begin to penetrate the fabric. This is the oil-resistant time.

[0050] Wash resistance: The wash resistance of the fabrics before and after finishing was tested according to AATCC-135. Specific standards are shown in Table 1. Tumble drying was selected as the drying method.

[0051] Table 1: AATCC-135 Washing Test Standards .

[0052] The oil-repellent effects of the oil-repellent agent on plain-weave cotton fabrics obtained in each case are shown in Table 2.

[0053] Table 2: Comparison of oil-repellent effects of different methods .

[0054] Table 2 shows that Examples 1, 2, 1, and 4 all imparted good oil-repellent properties to plain-weave cotton fabrics after oil-repellent finishing, with Example 2 showing the best oil-repellent effect, followed by Example 1. In Comparative Examples 1 and 4, no silica aerogel particles were added, resulting in insufficient roughening of the fiber surface and a slight reduction in oil-repellent performance.

[0055] The oil-repellent effect of the fabric before and after treatment in Example 2 is as follows: Figure 2 As shown, from the moment the oil droplets were first dropped onto the fabric (t=0s) to t=1300s and up to t=2600s, the oil droplets remained large particles with no change in shape. This confirms that the fluorine-free oil repellent provided in this application has a good oil-repellent effect.

[0056] In Comparative Example 2, octadecyl methacrylate, the most widely used monomer on the market, was used as the waterproof and oil-repellent monomer. Its oil droplet contact angle was 0°, indicating that octadecyl methacrylate alone has no oil-repellent effect.

[0057] Table 3: Comparison of oil-repellent effects of different methods .

[0058] Table 3 shows that Examples 1, 3, 2, and 5 all imparted good initial oil-repellent properties to plain-weave cotton fabrics after oil-repellent finishing. However, after three washes, the fluorine-free oil-repellent effect of the fabrics in Examples 1 and 2 weakened slightly. In Comparative Examples 2 and 5, no functional monomers were added, resulting in weaker bonding between the fluorine-free oil-repellent molecules and the fibers, leading to a significant decrease in the oil-repellent properties of the fabrics after washing. This indicates that the addition of functional monomers increases the bonding strength between the oil-repellent agent and the textile material, which is reflected in the oil-repellent performance after multiple washes.

[0059] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A fluorine-free oil repellent, characterized in that: The fluorine-free oil-repellent agent is prepared by reacting a fluorine-free oleophobic monomer with hydrophobic silica aerogel particles, and the preparation steps are as follows: Step 1: Weigh the cationic emulsifier and the nonionic emulsifier, stir them evenly, dissolve them in deionized water, and adjust the pH of the solution to 3-6 to obtain an emulsifier aqueous solution; Step 2: Weigh out the fluorine-free oil-resistant monomer with an umbrella-like liquid structure, the silica aerogel particles with a three-dimensional porous network structure, and the functional monomer, respectively. Disperse the three in a co-solvent, and slowly add the resulting dispersion to the emulsifier aqueous solution to obtain a mixed dispersion. Step 3: First, disperse the mixed dispersion to obtain a crude emulsion, then sonicate the crude emulsion to obtain a fine emulsion, then add the initiator that has been dissolved in deionized water in advance, heat to 70 °C, stir and react for 5 to 20 h, filter the liquid to obtain a fluorine-free oil inhibitor; The mass percentages of the above-mentioned materials added are as follows: Fluorine-free oleophobic monomers: 20-50%, Hydrophobic silica aerogel particles: 2~5%, Functional monomers 0.5-4%, The co-solvent content is 0-2%, and a value of 0 is not used. Cationic emulsifiers and nonionic emulsifiers: 2-5%, Initiator: 0.002–1% Deionized water: 40-70%, The fluorine-free oleophobic monomer is a methacryloyloxypropyl T-structure polysiloxane or a methacryloyloxypropyl-functionalized polydimethylsiloxane. The functional monomer is any one or a mixture of more than one of glycidyl methacrylate, hydroxyethyl methacrylate, methacrylic acid, methacrylamide, and N-vinylpyrrolidone. The surface of the hydrophobic silica aerogel particles has methacryloyloxypropyl or acryloyloxypropyl groups. The cationic emulsifier is any one or a mixture of more than one of octadecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, and hexadecyltrimethylammonium chloride; the nonionic emulsifier is any one or a mixture of more than one of fatty alcohol polyoxyethylene ether, isomeric alcohol polyoxyethylene ether, Span-80, and polyethylene glycol monolaurate. The initiator is any one or a mixture of more than one of azobisisobutyranin hydrochloride, azobisisobutyridine imidazoline hydrochloride, dimethyl azobisisobutyrate, potassium persulfate, and azobisisobutyronitrile.

2. The application of the fluorine-free oil repellent according to claim 1, characterized in that: Fluorine-free oil repellents are used in textile finishing.

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