Composite fluoride-free waterproof agent applied to glass fiber filter paper and preparation method of composite fluoride-free waterproof agent

Abstract

The invention relates to the technical field of glass fiber filter paper modification, in particular to a composite fluoride-free waterproof agent applied to glass fiber filter paper and a preparation method thereof.The composite fluoride-free waterproof agent applied to the glass fiber filter paper is prepared from, by mass, 1-5 parts of silicone oil, 4-8 parts of soft monomers, 10-15 parts of hard monomers and 5-10 parts of hydrophobic monomers, 2-3 parts of a functional monomer, 1-3 parts of a surfactant, 0.1-0.5 part of a chain transfer agent, 1-5 parts of a cosolvent, 0.1-1 part of an initiator and the balance of pure water. Glass fiber air filter paper obtained by dipping and drying the prepared composite fluoride-free water repellent agent emulsion and glass fiber paper filter paper has the advantages of good water resistance, high stiffness and high tensile strength.

Description

Technical Field

[0001] The invention belongs to the technical field of glass fiber filter paper modification, and particularly relates to a composite fluorine-free waterproofing agent applied to glass fiber filter paper and a preparation method thereof. Background Art

[0002] Glass fiber filter paper is widely used in air purification and high-temperature flue gas filtration due to its high porosity, high-temperature resistance, and chemical stability. However, the presence of numerous hydroxyl groups on the glass fiber surface makes it highly hydrophilic. This makes it susceptible to moisture absorption in humid environments, leading to a decrease in strength and filtration efficiency. This severely limits its service life in extreme operating conditions (such as high humidity and oil mist).

[0003] In order to give glass fiber filter paper a waterproof effect, the industry currently generally uses fluorine-containing waterproofing agents (such as PFOS and PFOA derivatives) to hydrophobically modify glass fiber filter paper. Although this can give the filter paper excellent water-repellent properties, it has the following defects: ① Environmental hazards: long-chain fluorocarbon compounds are difficult to degrade and pose a risk of bioaccumulation. They are strictly controlled by the EU REACH regulations and the global PFAS restriction list; ② Cost issues: Fluorine-containing raw materials are expensive, and energy consumption costs increase.

[0004] Chinese patent CN 119327182A describes a fluorine-free organosilicon waterproofing agent that is less susceptible to biodegradation and readily degrades, making it a safer and more environmentally friendly fluorine-free waterproofing agent. However, it also has drawbacks. First, the monomers used to prepare the waterproofing agent are expensive, such as trimethylethoxysilane. Second, it uses hydrochloric acid as a catalyst. Hydrochloric acid, a strong acid, is dangerous and falls into the third category of the list of precursor chemicals, making it difficult to obtain. Finally, there is a risk of gelation during storage of silica sol waterproofing agents.

[0005] The finishing process for glass fiber filter paper is relatively complex. Traditionally, waterproofing glass fiber filter paper requires the separate application of a water repellent, acrylic soft glue (to improve flexibility), and a hard glue (to enhance mechanical strength). This can lead to problems such as poor compatibility and uneven coating. Existing single-component water repellents cannot simultaneously meet the requirements for hydrophobicity and physical properties. Summary of the Invention

[0006] The object of the present invention is to provide a composite fluorine-free waterproofing agent for glass fiber filter paper and a preparation method thereof, so as to solve the technical problems in the prior art.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] The technical solutions provided by the present invention are as follows:

[0009] In a first aspect, the present invention provides a composite fluorine-free waterproofing agent for glass fiber filter paper, wherein the composite fluorine-free waterproofing agent for glass fiber filter paper specifically comprises the following components by weight: 1 to 5 parts of silicone oil, 4 to 8 parts of soft monomers, 10 to 15 parts of hard monomers, 5 to 10 parts of hydrophobic monomers, 2 to 3 parts of functional monomers, 1 to 3 parts of surfactants, 0.1 to 0.5 parts of chain transfer agents, 1 to 5 parts of cosolvents, 0.1 to 1 part of initiators, and the balance is pure water.

[0010] Preferably, the soft monomer includes at least one of ethyl acrylate, n-butyl acrylate, ethylhexyl acrylate, isooctyl acrylate, and lauryl acrylate.

[0011] Preferably, the hard monomer includes at least one of methyl methacrylate, methyl acrylate, styrene, acrylonitrile, acrylamide, vinyl acetate, and isobornyl methacrylate.

[0012] Preferably, the hydrophobic monomer includes at least one of behenyl acrylate, stearyl acrylate, lauryl acrylate, and isodecyl acrylate.

[0013] By adopting the above technical solution, through core-shell emulsion polymerization, soft and hard monomer polymers are used as the core of latex particles, and hydrophobic monomers are grafted onto the latex particles as the shell.

[0014] Preferably, the silicone oil includes at least one of hydroxyl-terminated silicone oil, vinyl-terminated silicone oil, and acrylate-based silicone oil; the silicone oil structural formula is shown in formula (I):

[0015]

[0016] In formula (I), R is selected from one of hydroxyl, vinyl and acrylate groups.

[0017] By adopting the above technical solution and using a shell design with silicone oil and long-chain alkyl groups in a directional arrangement, the filter paper can obtain a higher water contact angle.

[0018] Preferably, the functional monomer includes at least one of 1,6-hexanediol diacrylate, ethylene glycol dimethacrylate, and methacrylic acid.

[0019] Preferably, the surfactant includes at least one of a cationic surfactant and a nonionic surfactant; the cationic surfactant includes at least one of an amine salt and a quaternary ammonium salt; the nonionic surfactant includes at least one of a high-carbon fatty alcohol polyoxyethylene ether, fatty acid polyoxyethylene, sorbitan ester, and alkylphenol polyoxyethylene ether.

[0020] Preferably, the chain transfer agent is n-dodecyl mercaptan; and the cosolvent includes at least one of propylene glycol methyl ether, dipropylene glycol methyl ether, tripropylene glycol methyl ether, and dipropylene glycol butyl ether.

[0021] Preferably, the initiator is one of azobisisobutylamidine hydrochloride and persulfate.

[0022] In a second aspect, the present invention further provides a method for preparing a composite fluorine-free waterproofing agent for glass fiber filter paper, comprising the following steps:

[0023] Step (1) Core stage: Add soft monomer, hard monomer, functional monomer, emulsifier and deionized water to a reaction kettle; heat to 74-76° C., pre-emulsify at a stirring speed of 200-400 rpm for 20-40 minutes, add 1 / 2 of the initiator solution dropwise at a dropping speed of 0.4-0.6 mL / min, react until the emulsion exhibits obvious blue light, and keep warm for 20-40 minutes to obtain a mixed solution;

[0024] Step (2) Shell stage: The hydrophobic monomer, silicone oil, and the remaining soft and hard monomers are mixed with a cosolvent, and ultrasonically pre-emulsified at 45-55° C. for 20-40 minutes to obtain a pre-emulsion, and the pre-emulsion is added dropwise to the mixed solution using a constant pressure dropping funnel within 2.5-3.5 hours, and the remaining 1 / 2 initiator solution is added dropwise simultaneously;

[0025] Step (3) aging: keeping the reaction at 77-79°C for 2.5-3.5 hours;

[0026] After the step (4) is completed, the temperature is lowered to below 40° C., and the gel particles are removed by filtration through a 200-mesh sieve to obtain a composite fluorine-free waterproofing agent for glass fiber filter paper.

[0027] By adopting the above technical solution, the composite fluorine-free waterproofing agent does not need to be mixed with the waterproofing agent, acrylic soft glue and hard glue. It only needs to be diluted before use, avoiding the problem of compound compatibility.

[0028] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0029] 1. This invention utilizes core-shell emulsion polymerization, with soft and hard monomer polymers serving as the core of the latex particles and hydrophobic monomers grafted onto the latex particles to form the shell. The use of silicone oil and a directional arrangement of long-chain alkyl groups in the shell layer results in a high water contact angle for the filter paper and significantly improves the hydrostatic pressure resistance of the glass fiber filter paper, effectively resolving the industry challenge of poor dynamic water resistance in fluorine-free products.

[0030] 2. Compared with the physical mixing of two colloids, the composite emulsion of the present invention uses soft and hard monomers as the core of latex particles, which greatly improves the tensile strength of the glass fiber filter paper treated, and solves the brittle cracking problem of traditional waterproofing agents.

[0031] 3. The present invention synthesizes a composite fluorine-free waterproofing agent by core-shell emulsion polymerization. In the design of the composite fluorine-free waterproofing agent, the core-shell structure synergistically improves performance through functional zoning. Through the core-shell structure design, the core layer is designed to form a rigid core with a high glass transition temperature hard monomer, providing the high stiffness and deformation resistance required by the filter paper. The monomer can enhance the interfacial bonding between the core and the substrate to prevent the coating from falling off. The core formed in the seed polymerization stage serves as the reaction site for the subsequent shell growth to ensure the stability of the emulsion. The shell design grafts long alkane chains and silicone oil to the shell of the latex particles in the reaction stage. The shell hydrophobic monomer forms a directionally arranged hydrophobic barrier after heat treatment, which significantly improves the static waterproofness and dynamic anti-penetration ability. By feeding in stages, the gradient distribution of hydrophobic groups and the gradual assembly of soft and hard monomers are achieved, thereby improving the density and rigidity of the membrane while avoiding interface defects.

[0032] 4. The composite fluorine-free water repellent in the present invention does not require the application of a waterproofing agent, acrylic soft glue and hard glue. It only needs to be diluted before use, avoiding compounding compatibility problems, improving product stability, and completing the modification with a single coating, reducing process steps, being environmentally friendly and having a simple use process. The glass fiber air filter paper obtained by impregnating and drying the composite fluorine-free water repellent emulsion prepared by the present invention with glass fiber paper filter paper has good high resistance to hydrostatic pressure, excellent tensile strength and stiffness properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0034] Figure 1 It is the mass spectrum of the composite fluorine-free waterproofing agent prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0035] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0036] Unless otherwise specified, the reagents and raw materials used in the examples and comparative examples of the present invention were purchased from the market.

[0037] Example 1

[0038] This embodiment discloses a composite fluorine-free waterproofing agent for glass fiber filter paper.

[0039] It includes 5 parts of n-butyl acrylate (BA), 3 parts of ethyl acrylate (EA), 12 parts of methyl methacrylate (MMA), 3 parts of isobornyl methacrylate (IBOMA), 4 parts of acrylic acid ester-based silicone oil, 6 parts of octadecyl acrylate (SA), 2 parts of lauryl acrylate (LMA), 1 part of methacrylic acid (MAA), 1 part of 1,6-hexanediol diacrylate (HDDA), 2 parts of fatty alcohol polyoxyethylene ether (AEO-9), 0.2 parts of n-dodecyl mercaptan, 3 parts of dipropylene glycol butyl ether, 0.3 parts of azobisisobutyramidine hydrochloride, and 65 parts of deionized water.

[0040] The preparation process of the composite fluorine-free waterproofing agent applied to glass fiber filter paper includes the following steps:

[0041] Step (1) Core stage: 1 / 3 of the soft monomers BA and EA, 1 / 2 of the hard monomer MMA, all of the IBOMA, MAA, AEO-9, and water were added to a reactor, pre-emulsified at 74° C., stirred at 400 rpm for 20 min, and 1 / 2 of the initiator was added dropwise at a rate of 0.4 mL / min. The mixture was reacted until a blue light was emitted to obtain a mixed solution.

[0042] Step (2) Shell stage: the remaining hydrophobic monomers SA and LMA, acrylic acrylate-based silicone oil, HDDA, n-dodecyl mercaptan, and dipropylene glycol butyl ether were pre-emulsified at 55°C for 20 min and then added dropwise to the mixture within 3.5 h, and the remaining initiator was added dropwise simultaneously;

[0043] Step (3) aging: 79°C for 3.5 hours;

[0044] After the heat preservation in step (4) is completed, the temperature is lowered to below 40° C., and the gel particles are removed by filtration through a 200-mesh sieve to obtain a composite fluorine-free waterproofing agent for glass fiber filter paper with a white and slightly light blue light.

[0045] The infrared spectrum of the composite fluorine-free waterproofing agent is as follows Figure 1 As shown, the characteristic peaks are: 2955.83 / 2873.42cm -1 : corresponding to -CH3 asymmetric stretching and -CH2- symmetric stretching vibration (acrylate characteristics); 1726.92cm -1 : The strong absorption peak is the characteristic vibration of the aliphatic ester C=O; 1237.22-1159.27cm -1 :COC asymmetric stretching vibration (ester bond characteristics); 1065.27cm -1 :Si-O-Si stretching vibration (successful copolymerization of silicone oil); 842.11cm -1: Si-CH3 rocking vibration (confirmed by silicone component). Peak position assignment proves that the polymer was successfully synthesized.

[0046] Example 2

[0047] This embodiment discloses a composite fluorine-free waterproofing agent for glass fiber filter paper.

[0048] 6 parts of ethylhexyl acrylate (EHA), 15 parts of methyl methacrylate (MMA), 3 parts of acrylic acid acrylate-based silicone oil, 8 parts of octadecyl acrylate (SA), 1.5 parts of ethylene glycol dimethacrylate (EGDMA), 1 part of hexadecyltrimethylammonium bromide (CTAB), 1 part of fatty alcohol polyoxyethylene ether (AEO-9), 0.3 parts of n-dodecyl mercaptan, 4 parts of dipropylene glycol butyl ether, 0.4 parts of ammonium persulfate, and 60 parts of deionized water.

[0049] The preparation process of the composite fluorine-free waterproofing agent applied to glass fiber filter paper includes the following steps:

[0050] Step (1) Core stage: All hard monomers MMA, CTAB, and water were pre-emulsified at 76° C., stirred at 200 rpm for 40 min, and 1 / 2 of the initiator was added dropwise at a rate of 0.6 mL / min to form a hard core;

[0051] Step (2) Shell stage: After pre-emulsification of soft monomer (EHA), hydrophobic monomer (SA), acrylic acrylate-based silicone oil, AEO-9, n-dodecyl mercaptan, dipropylene glycol butyl ether, and EGDMA at 45°C for 40 min, they were added dropwise to the mixture over 2 h, and the initiator was added;

[0052] Step (3) aging: 77°C for 2.5 hours;

[0053] After the step (4) is completed, the temperature is lowered to below 40° C., and the gel particles are removed by filtration through a 200-mesh sieve to obtain a composite fluorine-free waterproofing agent emulsion with a white and slightly light blue color.

[0054] Comparative Example 1

[0055] Comparative Example 1 Compared with Example 1, in the process of preparing the composite fluorine-free waterproofing agent emulsion in Comparative Example 1, the hydrophobic monomers SA, LMA, and DA were omitted, and other conditions remained unchanged to obtain a white composite fluorine-free waterproofing agent emulsion.

[0056] Comparative Example 2

[0057] Comparative Example 2 Compared with Example 1, in the process of preparing the composite fluorine-free waterproofing agent emulsion in Comparative Example 2, all monomers containing the hydrophobic monomer are added to the reactor at one time, and other conditions remain unchanged to obtain a white composite fluorine-free waterproofing agent emulsion.

[0058] Experimental example

[0059] Treatment of glass fiber filter paper:

[0060] Clearly take 6 g of the composite fluorine-free waterproofing agent emulsion prepared in Example 1-2 and Comparative Example 1-2 and 94 g of water, mix and stir evenly, spread glass fiber paper flat and immerse it in the dilution for 30 seconds, then take it out and cure it at 150°C for 10 minutes to obtain a glass fiber air filter material.

[0061] The performance of the prepared glass fiber air filter material was tested, and the test method was as follows:

[0062] 1. Filtration efficiency and filtration resistance test

[0063] Glass fiber filter paper was treated with the emulsions prepared in Examples 1-2 of the present invention and Comparative Examples 1-2, and the filtration efficiency and filtration resistance were tested using an American TSI-8130 automatic filter material tester.

[0064] 2. Stiffness test

[0065] The stiffness test was performed on the glass fiber filter papers prepared in Examples 1-2 of the present invention and Comparative Examples 1-2.

[0066] 3. Tensile strength

[0067] A tensile test was performed on the glass fiber filter papers prepared in Examples 1-2 of the present invention and Comparative Examples 1-2.

[0068] 4. Hydrostatic pressure test

[0069] The glass fiber filter papers prepared in Examples 1-2 and Comparative Examples 1-2 of the present invention were subjected to hydrostatic pressure tests according to the national standard GB / T4744-2013. The results are shown in Table 1.

[0070] Table 1

[0071]

[0072] The results in Table 1 show that the core-shell emulsion polymerization method, with its core-shell structure designed and soft and hard monomers as the latex particle core, effectively improves the bonding strength of the fluorine-free water repellent with the glass fiber after drying and film formation, imparting excellent stiffness and tensile strength to the glass fiber filter paper. The hydrophobic monomers used as the latex particle shell impart excellent hydrophobicity to the glass fiber filter paper. Combining acrylic adhesive with the water repellent to form a composite water repellent eliminates the need for further compounding, optimizes the application process, and simultaneously ensures high filtration efficiency and other excellent properties of the filter paper.

[0073] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

[0074] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to specific embodiments. Obviously, many modifications and variations are possible based on the contents of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A composite fluorine-free waterproofing agent for glass fiber filter paper, characterized in that: The raw materials of the composite fluorine-free waterproofing agent applied to glass fiber filter paper are composed of the following components in parts by mass (weight): 1 to 5 parts of silicone oil, 4 to 8 parts of soft monomers, 10 to 15 parts of hard monomers, 5 to 10 parts of hydrophobic monomers, 2 to 3 parts of functional monomers, 1 to 3 parts of surfactants, 0.1 to 0.5 parts of chain transfer agents, 1 to 5 parts of cosolvents, 0.1 to 1 part of initiators, and the balance is pure water.

2. The composite fluorine-free waterproofing agent for glass fiber filter paper according to claim 1, characterized in that: The silicone oil includes at least one of hydroxyl-terminated silicone oil, vinyl-terminated silicone oil, and acrylate-based silicone oil; the silicone oil structural formula is shown in formula (I): In formula (I), R is selected from one of hydroxyl, vinyl and acrylate groups.

3. The composite fluorine-free waterproofing agent for glass fiber filter paper according to claim 1, characterized in that: The soft monomer includes at least one of ethyl acrylate, n-butyl acrylate, ethylhexyl acrylate, isooctyl acrylate, and lauryl acrylate.

4. The composite fluorine-free waterproofing agent for glass fiber filter paper according to claim 1, characterized in that: The hard monomer includes at least one of methyl methacrylate, methyl acrylate, styrene, acrylonitrile, acrylamide, vinyl acetate, and isobornyl methacrylate.

5. The composite fluorine-free waterproofing agent for glass fiber filter paper according to claim 1, characterized in that: The hydrophobic monomer includes at least one of behenyl acrylate, stearyl acrylate, lauryl acrylate, and isodecyl acrylate.

6. The composite fluorine-free waterproofing agent for glass fiber filter paper according to claim 1, characterized in that: The functional monomer includes at least one of 1,6-hexanediol diacrylate, ethylene glycol dimethacrylate, and methacrylic acid.

7. The composite fluorine-free waterproofing agent for glass fiber filter paper according to claim 1, characterized in that: The surfactant includes at least one of a cationic surfactant and a nonionic surfactant; the cationic surfactant includes at least one of an amine salt and a quaternary ammonium salt; the nonionic surfactant includes at least one of a high-carbon fatty alcohol polyoxyethylene ether, fatty acid polyoxyethylene, anhydrous sorbitan ester, and alkylphenol polyoxyethylene ether.

8. The composite fluorine-free waterproofing agent for glass fiber filter paper according to claim 1, characterized in that: The chain transfer agent is n-dodecyl mercaptan; the cosolvent includes at least one of propylene glycol methyl ether, dipropylene glycol methyl ether, tripropylene glycol methyl ether, and dipropylene glycol butyl ether.

9. The composite fluorine-free waterproofing agent for glass fiber filter paper according to claim 1, characterized in that: The initiator is one of azobisisobutylamidine hydrochloride and persulfate.

10. A method for preparing a composite fluorine-free waterproofing agent for glass fiber filter paper according to any one of claims 1 to 9, characterized in that: The steps include: Step (1) Core stage: Add soft monomer, hard monomer, functional monomer, emulsifier and deionized water to a reaction kettle; heat to 74-76° C., stir at 200-400 rpm for pre-emulsification for 20-40 minutes, then dropwise add 1 / 2 of the initiator solution at a rate of 0.4-0.6 mL / min, react until the emulsion exhibits a distinct blue light, and then keep warm for 20-40 minutes to obtain a mixed solution; Step (2) Shell stage: The hydrophobic monomer, silicone oil, and the remaining soft and hard monomers are mixed with a cosolvent, and ultrasonically pre-emulsified at 45-55° C. for 20-40 minutes to obtain a pre-emulsion, and the pre-emulsion is added dropwise to the mixed solution using a constant pressure dropping funnel within 2.5-3.5 hours, and the remaining 1 / 2 initiator solution is added dropwise simultaneously; Step (3) aging: keeping the reaction at 77-79°C for 2.5-3.5 hours; After the step (4) is completed, the temperature is lowered to below 40° C., and the gel particles are removed by filtration through a 200-mesh sieve to obtain a composite fluorine-free waterproofing agent for glass fiber filter paper.

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