Preparation method of fluorine-free waterproof and oil-proof agent for paper secondary processing

Abstract

The application discloses a preparation method of a fluorine-free waterproof and oil-proof agent for paper secondary processing, and relates to the technical field of waterproof agents, in particular to the following: a special acrylate polymer is synthesized by adopting a reactive emulsifier, introducing an organic monomer containing a special group, and adding a silane coupling agent with a special structure through an emulsion polymerization method, so that the waterproof performance required after paper secondary processing is realized. The method has a simple process and is easy to industrialize. The raw materials and the raw material consumption all meet the national standard GB9685-2016 food contact material and product additive use standard. The prepared waterproof and oil-proof agent is non-toxic and harmless, can be applied to the food material industry and other fields with waterproof and oil-proof requirements, has important application value and economic benefits, and through process control, the emulsion is controlled in a small particle size, the permeability of the emulsion to paper is increased, and better application effect can be achieved.

Description

Technical Field

[0001] This invention relates to the field of waterproofing agent technology, specifically to a method for preparing a fluorine-free waterproofing and oil-repellent agent for secondary paper processing. Background Technology

[0002] With the deepening of national environmental protection policies and the market's demand for cost control, the use of secondary wood pulp fiber raw materials is increasing. This has led to a gradual increase in impurities in the pulp that affect paper performance, thus requiring increasingly stringent requirements for paper water-resistant chemicals. To achieve desired performance, most paper waterproofing agents on the market currently contain fluorides. However, due to the toxicity and environmental pollution associated with fluorides, they pose certain risks to health and the environment. Per- and polyfluoroalkyl substances (PFAS) are among the most difficult-to-degrade organic pollutants discovered worldwide, exhibiting a high capacity for bioaccumulation. When ingested by organisms, they do not accumulate in adipose tissue but instead bind to proteins and remain in the blood, accumulating in tissues such as the liver, kidneys, and muscles, exhibiting significant bioaccumulation. In recent years, bans on the use of fluorides have been gradually implemented worldwide. Therefore, researching a fluoride-free paper waterproofing agent preparation method is of great significance. Furthermore, current paper waterproofing agents on the market have relatively limited performance and lack good oil-repellent properties, which does not provide a good solution for certain fields, such as the food paper industry.

[0003] In the prior art, some methods for preparing fluorine-free paper waterproofing agents have been disclosed. For example, Chinese Patent Application No. CN202211552628.3 discloses a fluorine-free paper waterproofing agent and its preparation method, relating to the field of waterproofing agent technology. The fluorine-free paper waterproofing agent comprises the following components by weight: 50-60 parts silicone resin, 1-3 parts paraffin wax, 3-7 parts silicone oil, 4-9 parts ethanol, 10-12 parts cationic wax dispersion, 3-7 parts crosslinking agent, 4-8 parts methyltriethylsiloxane, 1-8 parts emulsifier, and 10-15 parts auxiliary agent. In this invention, the addition of isophorone diisocyanate and castor oil dimer improves the waterproofing performance of the paper, especially significantly enhancing its durability. Even after repeated water contact, the waterproofing performance remains intact. Furthermore, the addition of silicone resin improves corrosion resistance, thus extending the paper's lifespan. This invention is highly practical and represents a significant advancement. Although the waterproofing agent in this invention is fluorine-free, the raw material used, isophorone diisocyanate, is harmful to both the human body and the environment.

[0004] To address the aforementioned issues, existing technologies, such as Chinese Patent Application No. CN202110035917.5, disclose a method for preparing a high-efficiency paper waterproofing agent. This invention's waterproofing agent uses starch as a raw material. After pretreatment, the starch is combined with a specially structured monomer, methacryloyloxyethyl dimethylbenzylammonium chloride. Under a novel polymerization process, the self-emulsifying effect of this polymerizable monomer achieves the technical requirements of soap-free emulsion polymerization. This not only solves the problem of reduced paper waterproofing caused by the introduction of large amounts of emulsifiers in emulsion polymerization but also further improves the film-forming properties and stability of the emulsion, overcoming the shortcomings of existing styrene-acrylic surface sizing agents and achieving excellent paper waterproofing. Although the waterproofing agent in this invention uses environmentally friendly raw materials, it requires high precision in raw material stability and production process operation. The degree of starch hydrolysis and the grafting effect of the monomer directly affect the product quality, causing instability. Summary of the Invention

[0005] This invention provides a method for preparing a fluorine-free waterproof and oil-resistant agent for secondary paper processing. This method solves the problems mentioned in the background art, such as the limited performance of commercially available paper waterproof agents, the lack of good oil-resistant properties, and the high requirements for raw material stability and production process precision when using environmentally friendly raw materials, which affects the stability of quality.

[0006] This invention provides the following technical solution: a method for preparing a fluorine-free waterproof and oil-resistant agent for secondary paper processing, wherein the fluorine-free waterproof and oil-resistant agent for secondary paper processing is composed of the following substances in parts by weight: 55-65 parts deionized water, 2-5 parts reactive emulsifier, 16-20 parts acrylate monomer, 22-25 parts methacrylate monomer, 1.1-1.6 parts silane coupling agent, 0.4-0.8 parts hydrophilic carboxylic acid monomer, 0.6-1 part special crosslinking monomer, 0.15-0.25 parts persulfate, 0.05-0.08 parts oily oxidant, 0.05-0.08 parts water-soluble antioxidant, and 0.05-0.08 parts pH adjuster;

[0007] Wherein: the reactive emulsifier is one or two of sodium allyl succinate or sodium allyl hydroxypropanesulfonate; the silane coupling agent is one or two of vinyltrimethoxysilane or vinyltriethoxysilane; and the special crosslinking monomer is one or two of hydroxyethyl acrylate or hydroxyethyl methacrylate.

[0008] The preparation process of the above-mentioned fluorine-free waterproof and oil-resistant agent for secondary paper processing is as follows:

[0009] S1: Add reactive emulsifier and deionized water to the reactor, heat to 80℃-82℃, introduce nitrogen gas, and start stirring;

[0010] S2: Add reactive emulsifier and deionized water to the high-level tank, then add acrylate monomer, methacrylate monomer, hydrophilic carboxylic acid monomer, and special crosslinking monomer, and start stirring at the same time until a uniform milky white dispersion is formed for later use.

[0011] S3: Add a portion of persulfate aqueous solution to the reactor, and then start simultaneously adding the emulsion in the high-level tank and the remaining persulfate aqueous solution. Control the adding temperature at 80-82℃ and the adding time at 3-3.5h. After the adding is complete, add the silane coupling agent to the reactor.

[0012] S4: After completion, keep warm for 1 hour, then cool down to 72℃, add oily oxidant, keep warm for 10 minutes; then add water-soluble antioxidant, keep warm for 20 minutes;

[0013] S5: Cool down to 45℃, add pH adjuster, and adjust the pH to 7-9;

[0014] S6: Filter the material through a 200-mesh sieve to obtain the final product.

[0015] Preferably, the acrylate monomer is one or both of n-butyl acrylate or isooctyl acrylate.

[0016] Preferably, the methacrylate monomer is one or both of methyl methacrylate or butyl methacrylate.

[0017] Preferably, the hydrophilic carboxylic acid monomer refers to one or both of acrylic acid or methacrylic acid.

[0018] Preferably, the persulfate is one or both of ammonium persulfate or potassium persulfate.

[0019] Preferably, the oily oxidant is tert-butyl hydroperoxide; the water-soluble antioxidant is one or both of sodium metabisulfite or ascorbic acid.

[0020] Preferably, the stirring speed in S1 is 150-200 r / min; the stirring speed in S2 is 400-500 r / min, and the stirring time is 20 min.

[0021] Preferably, the concentration of the persulfate aqueous solution in S3 is 10%, and a persulfate aqueous solution with a concentration of 9.7% is first added to the reaction vessel.

[0022] Preferably, the pH adjuster is ammonia.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. This method for preparing a fluorine-free waterproof and oil-repellent agent for secondary paper processing involves synthesizing a special acrylate polymer via emulsion polymerization to achieve the required waterproof performance after paper processing. This method is simple and easy to industrialize. All raw materials and their dosages comply with the national standard GB9685-2016 "Standards for the Use of Additives in Food Contact Materials and Products." The resulting waterproof and oil-repellent agent is non-toxic and harmless, and can be applied to the food industry and other fields with waterproof and oil-repellent requirements, demonstrating significant application value and economic benefits.

[0025] 2. The preparation method of this paper secondary processing using a fluorine-free waterproof and oil-resistant agent employs a reactive emulsifier. Most emulsifier molecules can be bonded to the molecular chain through polymerization, reducing the presence of emulsifiers in small molecule form and preventing desorption, migration, and aggregation, thereby improving the water resistance and whitening properties of the emulsion coating. The introduction of organic monomers containing special groups makes the latex particles more compact after drying, providing both waterproof and oil-resistant effects. The addition of a specially structured silane coupling agent allows the silanol bonds generated by the hydrolysis of the coupling agent on the latex particle surface to crosslink, causing the latex particles to condense and form a network structure, thus improving the adhesion and water resistance of the inorganic substrate.

[0026] 3. The preparation method of the paper secondary processing using a fluorine-free waterproof and oil-resistant agent, through process control, controls the emulsion to a smaller particle size, which increases the emulsion's permeability to the paper and achieves better application results. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the sample performance test results. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] This invention provides a paper secondary processing waterproofing agent, composed of the following substances in parts by weight: 55-65 parts deionized water, 2-5 parts reactive emulsifier, 16-20 parts acrylate monomer, 22-25 parts methacrylate monomer, 1.1-1.6 parts silane coupling agent, 0.4-0.8 parts hydrophilic carboxylic acid monomer, 0.6-1 part special crosslinking monomer, 0.15-0.25 parts persulfate, 0.05-0.08 parts oily oxidant, 0.05-0.08 parts water-soluble antioxidant, and 0.05-0.08 parts pH adjuster.

[0030] Among them, reactive emulsifiers refer to one or both of sodium allyl succinate or sodium allyl hydroxypropanesulfonate. By setting reactive emulsifiers, most emulsifier molecules can be bonded to the molecular chain through polymerization reaction, reducing the presence of emulsifiers in the form of small molecules, avoiding the desorption, migration and aggregation of emulsifiers, thereby improving the water whitening resistance of the emulsion coating film, and improving the penetration of the emulsion into paper, thus achieving better application results.

[0031] Acrylic ester monomers refer to one or both of n-butyl acrylate or isooctyl acrylate. Methacrylate monomers refer to one or both of methyl methacrylate or butyl methacrylate. Silane coupling agents refer to one or both of vinyltrimethoxysilane or vinyltriethoxysilane. By adding silane coupling agents with special structures, the silanol bonds generated by the hydrolysis of the coupling agent on the surface of the latex particles can play a cross-linking role. Furthermore, the silanol bonds or hydroxyl groups contained in the silane coupling agent-modified emulsion itself can form hydrogen bonds or condensation, thereby causing the emulsion particles to condense together to form a network structure, thus improving the adhesion, water resistance, heat resistance, moisture resistance, and solvent resistance of the inorganic substrate.

[0032] Hydrophilic carboxylic acid monomers refer to one or both of acrylic acid or methacrylic acid. Special crosslinking monomers refer to one or both of hydroxyethyl acrylate or hydroxyethyl methacrylate. By introducing organic monomers containing special groups, the latex particles become more densely packed after the emulsion dries and forms a film, providing both waterproof and oil-repellent effects. Persulfates refer to one or both of ammonium persulfate or potassium persulfate. Oily oxidizing agents refer to tert-butyl hydroperoxide. Water-soluble antioxidants refer to one or both of sodium metabisulfite or ascorbic acid. pH adjusters refer to ammonia.

[0033] The preparation process of the above-mentioned fluorine-free waterproof and oil-resistant agent for secondary paper processing is as follows:

[0034] S1: Add reactive emulsifier and deionized water to the reactor, heat to 80℃-82℃, introduce nitrogen gas, and start stirring at a speed of 150-200r / min.

[0035] S2: Add reactive emulsifier and deionized water to the high-level tank, then add acrylate monomer, methacrylate monomer, hydrophilic carboxylic acid monomer and special crosslinking monomer. At the same time, start stirring at a speed of 400-500 r / min for 20 min to form a uniform milky white dispersion for later use.

[0036] S3: Add a portion of the persulfate aqueous solution to the reactor, then simultaneously add the emulsion from the high-level tank and the remaining persulfate aqueous solution. Control the adding temperature at 80-82℃ and the adding time at 3-3.5 hours. After the addition is complete, add the silane coupling agent to the reactor. In this step, the concentration of the persulfate aqueous solution is 10%, and a 9.7% persulfate aqueous solution is added to the reactor first.

[0037] S4: After completion, keep warm for 1 hour. Then cool to 72℃, add oily oxidant, keep warm for 10 minutes; then add water-soluble antioxidant, keep warm for 20 minutes.

[0038] S5: Cool down to 45℃, add pH adjuster, and adjust the pH to 7-9;

[0039] S6: Filter the material through a 200-mesh sieve to obtain the final product.

[0040] The present application will be further described below through some embodiments.

[0041] Case 1:

[0042] S1: Add 7.4g of sodium allyl succinate and 240g of deionized water to the reactor, heat to 80℃-82℃, introduce nitrogen gas, and start stirring at a speed of 150-200r / min.

[0043] S2: Add 13.8g of sodium allyl succinate and 188g of deionized water to the high-level tank, then add 165g of n-butyl acrylate, 220g of methyl methacrylate, 3.8g of acrylic acid and 6.4g of hydroxyethyl methacrylate. At the same time, start stirring at a speed of 400-500r / min for 20min to form a uniform milky white dispersion for later use.

[0044] S3: Add 1.4g of a 10% potassium persulfate aqueous solution to the reactor, then simultaneously add the emulsion from the high-level tank and the remaining 14.4g of the 10% potassium persulfate aqueous solution. Control the adding temperature at 80-82℃ and the adding time at 3-3.5h. After the addition is complete, add 10g of vinyltrimethoxysilane to the reactor.

[0045] S4: After completion, keep warm for 1 hour. Then cool to 72℃, add 0.48g of tert-butyl hydroperoxide, keep warm for 10 minutes; then add 0.48g of ascorbic acid, keep warm for 20 minutes;

[0046] S5: Cool to 45℃, add 4.8g of ammonia water with 25% solid content, and adjust the pH to 7-9;

[0047] S6: Filter the material through a 200-mesh sieve to obtain the final product.

[0048] Case 2:

[0049] S1: Add 7.4g of sodium allyl hydroxypropanesulfonate and 240g of deionized water to the reactor, heat to 80℃-82℃, introduce nitrogen gas, and start stirring at a speed of 150-200r / min.

[0050] S2: Add 13.8g of sodium allyl hydroxypropanesulfonate and 188g of deionized water to the high-level tank, then add 165g of isooctyl acrylate, 220g of butyl methacrylate, 3.8g of methacrylic acid and 6.4g of hydroxyethyl methacrylate. At the same time, start stirring at a speed of 400-500r / min for 20min to form a uniform milky white dispersion for later use.

[0051] S3: Add 1.4g of a 10% potassium persulfate aqueous solution to the reactor, then simultaneously add the emulsion from the high-level tank and the remaining 14.4g of the 10% potassium persulfate aqueous solution. Control the adding temperature at 80-82℃ and the adding time at 3-3.5h. After the adding is complete, add 12g of vinyltriethoxysilane to the reactor.

[0052] S4: After completion, keep warm for 1 hour. Then cool to 72℃, add 0.48g of tert-butyl hydroperoxide, keep warm for 10 minutes; then add 0.48g of ascorbic acid, keep warm for 20 minutes;

[0053] S5: Cool to 45℃, add 4.8g of ammonia water with 25% solid content, and adjust the pH to 7-9;

[0054] S6: Filter the material through a 200-mesh sieve to obtain the final product.

[0055] Case 3:

[0056] S1: Add 4.8g of sodium allyl succinate, 2.6g of sodium allyl hydroxypropanesulfonate and 240g of deionized water to the reactor, heat to 80℃-82℃, introduce nitrogen gas, and start stirring at a speed of 200-250r / min.

[0057] S2: Add 11.8g of sodium allyl succinate, 2g of sodium allyl hydroxypropanesulfonate and 188g of deionized water to the high-level tank, then add 165g of n-butyl acrylate, 120g of butyl methacrylate, 100g of methyl methacrylate, 3.8g of methacrylic acid and 6.4g of hydroxyethyl methacrylate. At the same time, start stirring at a speed of 400-500r / min for 20min to form a uniform milky white dispersion for later use.

[0058] S3: Add 1.4g of a 10% potassium persulfate aqueous solution to the reactor, then simultaneously add the emulsion from the high-level tank and the remaining 14.4g of the 10% potassium persulfate aqueous solution. Control the adding temperature at 80-82℃ and the adding time at 3-3.5h. After the addition is complete, add 12g of vinyltrimethoxysilane to the reactor.

[0059] S4: After completion, keep warm for 1 hour. Then cool to 72℃, add 0.48g of tert-butyl hydroperoxide, keep warm for 10 minutes; then add 0.48g of ascorbic acid, keep warm for 20 minutes;

[0060] S5: Cool to 45℃, add 4.8g of ammonia water with 25% solid content, and adjust the pH to 7-9;

[0061] S6: Filter the material through a 200-mesh sieve to obtain the final product.

[0062] The performance of samples manufactured using the solution in Case 1, the solution in Case 2, and the solution in Case 3 was tested. The application performance data of the samples are shown in the appendix to the instruction manual. Figure 1 As shown.

[0063] Included in the instruction manual Figure 1 It is known that the paper secondary waterproofing agent prepared by the present invention has excellent waterproof and oil-proof properties after paper coating application tests, and has a low polymerization slag rate, resulting in very high industrial production efficiency.

[0064] All standard parts used in this invention can be purchased from the market, and irregularly shaped parts can be customized according to the description and drawings. The specific connection methods of each part adopt conventional methods such as bolts, rivets, and welding that are mature in the prior art. The machinery, parts and equipment adopt conventional models in the prior art, which will not be described in detail here. The contents not described in detail in this specification belong to the prior art known to those skilled in the art. Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a fluorine-free waterproof and oil-resistant agent for secondary paper processing, characterized in that: The fluorine-free waterproof and oil-resistant paper secondary processing agent is composed of the following substances in parts by weight: 55-65 parts deionized water, 2-5 parts reactive emulsifier, 16-20 parts acrylate monomer, 22-25 parts methacrylate monomer, 1.1-1.6 parts silane coupling agent, 0.4-0.8 parts hydrophilic carboxylic acid monomer, 0.6-1 part special crosslinking monomer, 0.15-0.25 parts persulfate, 0.05-0.08 parts oily oxidant, 0.05-0.08 parts water-soluble antioxidant, and 0.05-0.08 parts pH adjuster; Wherein: the reactive emulsifier is one or both of sodium allyl succinate or sodium allyl hydroxypropanesulfonate; the silane coupling agent is one or both of vinyltrimethoxysilane or vinyltriethoxysilane; the special crosslinking monomer is one or both of hydroxyethyl acrylate or hydroxyethyl methacrylate; the acrylate monomer is one or both of n-butyl acrylate or isooctyl acrylate. The preparation process of the above-mentioned fluorine-free waterproof and oil-resistant agent for secondary paper processing is as follows: S1: Add reactive emulsifier and deionized water to the reactor, heat to 80℃-82℃, introduce nitrogen gas, and start stirring at a speed of 150-200r / min. S2: Add reactive emulsifier and deionized water to the high-level tank, then add acrylate monomer, methacrylate monomer, hydrophilic carboxylic acid monomer and special crosslinking monomer, and start stirring at the same time until a uniform milky white dispersion is formed for later use. The stirring speed is 400-500 r / min, and the stirring time is 20 min. S3: Add a portion of persulfate aqueous solution to the reactor, and then simultaneously add the emulsion and the remaining persulfate aqueous solution from the high-level tank. Control the adding temperature at 80-82℃ and the adding time at 3-3.5h. After the adding is complete, add the silane coupling agent to the reactor. The concentration of the persulfate aqueous solution is 10%, and add the 9.7% persulfate aqueous solution to the reactor first. S4: After completion, keep warm for 1 hour, then cool down to 72℃, add oily oxidant, keep warm for 10 minutes; then add water-soluble antioxidant, keep warm for 20 minutes; S5: Cool down to 45℃, add pH adjuster, and adjust the pH to 7-9; pH adjuster is ammonia water; S6: Filter the material through a 200-mesh sieve to obtain the final product.

2. The method for preparing a fluorine-free waterproof and oil-resistant agent for secondary paper processing according to claim 1, characterized in that: The methacrylate monomer is one or both of methyl methacrylate or butyl methacrylate.

3. The method for preparing a fluorine-free waterproof and oil-resistant agent for secondary paper processing according to claim 2, characterized in that: The hydrophilic carboxylic acid monomer refers to one or both of acrylic acid or methacrylic acid.

4. The method for preparing a fluorine-free waterproof and oil-resistant agent for secondary paper processing according to claim 3, characterized in that: The persulfate is one or both of ammonium persulfate or potassium persulfate.

5. The method for preparing a fluorine-free waterproof and oil-resistant agent for secondary paper processing according to claim 4, characterized in that: The oily oxidant is tert-butyl hydroperoxide; the water-soluble antioxidant is one or both of sodium metabisulfite or ascorbic acid.

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