A fluorine-free environmentally friendly oil-proof agent for paper base and its preparation method and application

Abstract

The invention discloses a fluorine-free environmentally friendly oil-proof agent for paper base and its preparation method and application, belonging to the technical field of fine chemical industry. The oil-proof agent comprises the following components in parts by weight: 30-50 parts of modified cellulose, 10-20 parts of gelatin, 9-18 parts of acrylate monomers, 20-30 parts of polyurethane prepolymers, 2-5 parts of modified nano-silicon dioxide and 1-3 parts of polyether-modified siloxane; the modified cellulose is obtained by esterification and graft polymerization of carboxymethyl cellulose; the modified nano-silicon dioxide is obtained by organic treatment and interfacial polymerization of nano-silicon dioxide; the oil-proof agent of the invention is a fluorine-free formula, and the synergistic effect of each component not only avoids the potential harm of fluoride to the environment and health, but also improves the oil-proof performance, mechanical properties, tensile strength and chemical stability of the oil-proof agent.

Description

Technical Field

[0001] The invention belongs to the technical field of fine chemicals, and in particular relates to a fluorine-free, environmentally friendly oil-proofing agent for paper bases, and a preparation method and application thereof. Background Art

[0002] In the application of paper and paper-based materials, oil resistance is an important indicator. Traditional oil-proof agents mostly use fluorinated compounds. Although these compounds have good oil-proof effects, they have environmental pollution and biological safety issues.

[0003] Traditional oil-proofing agents often contain fluorine. Although fluorine can reduce the surface tension of paper and give paper good oil-proofing properties, fluorine-containing compounds are not easy to decompose, easily aggregate in organisms, and ultimately endanger human health through the food chain. Therefore, many countries have restricted the use of fluorine-containing compounds in food packaging. Fluorine-free oil-proofing agents are more environmentally friendly, but how to achieve good oil-proofing effects while ensuring environmental protection has become a technical problem that needs to be solved urgently. Therefore, the present invention develops a fluorine-free environmentally friendly oil-proofing agent for paper base and its preparation method and application, which are used to solve the problems of insufficient oil-proofing effects and poor stability of traditional fluorine-free oil-proofing agents in the prior art, especially when processing food packaging with high oil content, there is no further refinement of the preparation process and the addition of improved additives to improve the oil-proofing effect of the oil-proofing agent, and the lack of long-term stability on the surface of paper-based materials. Summary of the invention

[0004] The object of the present invention is to provide a fluorine-free environmentally friendly oil-proof agent for paper-based materials, and a preparation method and application thereof, so as to solve the problems that the conventional fluorine-free oil-proof agent in the prior art is insufficient in oil-proof effect and poor in stability, especially when processing food packaging with a high oil content, the oil-proof effect of the oil-proof agent is not improved from the perspective of further refining the preparation process and adding improved auxiliary agents, and the technical problem of lack of long-term stability on the surface of paper-based materials.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A fluorine-free environmentally friendly oil-proof agent for paper base comprises the following components in parts by weight: 30-50 parts of modified cellulose, 10-20 parts of gelatin, 9-18 parts of acrylate monomers, 20-30 parts of polyurethane prepolymers, 2-5 parts of modified nano-silicon dioxide and 1-3 parts of polyether-modified siloxane; the modified cellulose is obtained by modifying carboxymethyl cellulose through esterification and graft polymerization; the acrylate monomer is a mixture of methyl methacrylate and butyl acrylate, the mass ratio of methyl methacrylate to butyl acrylate is 2:1, the polyurethane prepolymer is a mixture of polyether polyurethane and polyester polyurethane, the mass ratio of polyether polyurethane to polyester polyurethane is 1:1, and the polyether polyurethane and polyester polyurethane are purchased from Dongguan Jiurui Plastic Raw Materials Co., Ltd.; the modified nano-silicon dioxide is obtained by modifying nano-silicon dioxide through organic treatment and interfacial polymerization; and the ether-modified siloxane is purchased from Nanjing Dahai New Material Technology Co., Ltd.

[0006] The preparation method of the modified cellulose comprises the following steps: S1, esterification: adding carboxymethyl cellulose to solution 1, adding sulfuric acid, stirring the reaction, after the reaction is completed, adjusting the pH with NaOH solution, centrifuging, then washing with water, and drying to obtain esterified cellulose; S2, graft polymerization: dispersing the esterified cellulose in dimethylformamide, adding methyl methacrylate, butyl acrylate and ammonium persulfate, stirring for reaction, and after completion, centrifuging, washing and drying to obtain graft copolymerized cellulose; Furthermore, the carboxymethyl cellulose in S1 was purchased from Renqiu Jinyu Chemical Co., Ltd., and solution one was prepared by dissolving caprylic anhydride and stearic anhydride in anhydrous ethanol in a mass ratio of 1:1. The mass concentration of solution one was 8-10wt%, the mass ratio of carboxymethyl cellulose to anhydride was 1-2:1, the mass concentration of sulfuric acid was 96-98%, the volume ratio of sulfuric acid to anhydrous ethanol was 1:200, the temperature of the stirring reaction was 60-80°C, the time of the stirring reaction was 2-6 hours, the concentration of the NaOH solution was 1M, and the pH was adjusted to 7- 7.5, washed with water 2-3 times, and dried at 60-65°C; the mass volume ratio of esterified cellulose to dimethylformamide in S2 is 10-20:100 g / mL, the mass ratio of esterified cellulose to methyl methacrylate is 1:0.5-0.8, the mass ratio of methyl methacrylate to butyl acrylate is 1:1, the mass concentration of ammonium persulfate is 1-5wt%, the stirring reaction temperature is 60-80°C, the stirring reaction time is 2-6 hours, washed with dimethylformamide 2-3 times, and dried at 60-65°C.

[0007] The preparation method of the nano silicon dioxide comprises the following steps: Q1. Pretreatment: disperse nano-silicon dioxide in water, perform ultrasonic treatment, add stearic acid, stir and react to obtain a reaction suspension; Q2. Interfacial polymerization: Add methyl methacrylate and benzoyl peroxide to the reaction suspension, stir to react, and after completion, filter, wash, and dry to obtain modified nano-silica.

[0008] Furthermore, the mass volume ratio of nano-silica to water in Q1 is 10-20:100 g / mL, ultrasonic treatment is performed for 30-40 minutes, the mass ratio of nano-silica to stearic acid is 5:0.8-1, stirring reaction is carried out for 2-3 hours, and the reaction temperature is 60-65°C. The mass ratio of nano-silica to methyl methacrylate in Q2 is 5:0.8-1, the mass ratio of nano-silica to benzoyl peroxide is 100:1, the reaction temperature is 70-75°C, the reaction time is 2-4 hours, washing is carried out 2-3 times with 75% ethanol, and the drying temperature is 60-65°C.

[0009] A method for preparing a fluorine-free environmentally friendly oil-proofing agent for paper substrates comprises the following steps: (1) Preparation of the main emulsion: Add modified cellulose, gelatin, acrylate monomer, polyurethane prepolymer and nano-silica into a normal pressure reactor, and add polyether-modified siloxane at the same time, stir and react. After the reaction is completed, cool naturally to room temperature to obtain a preliminary oil-proofing agent solution; (2) Degassing and concentration: The gas in the vacuum reactor is extracted by a vacuum pump, and the preliminary oil repellent solution is transferred to the vacuum reactor by a screw pump, and then degassed and concentrated to obtain a concentrated oil repellent solution; (3) Colloid mill: The concentrated oil repellent solution is finely dispersed through a colloid mill to obtain a finely dispersed oil repellent solution; (4) Emulsification stage: The finely dispersed oil repellent solution is transferred to a high shear emulsification tank through screw pump 2, and the solution is further dispersed and emulsified by high shear force to obtain an emulsified oil repellent solution; the emulsified oil repellent solution is transferred to a temporary storage tank through screw pump 3; (5) Low temperature concentration: The finely dispersed oil repellent solution is transferred to a three-effect falling film evaporator through a screw pump 4 for low temperature continuous evaporation concentration to obtain a stable oil repellent solution; (6) Storage and packaging: The stable oil repellent solution is transferred to a finished product can and packaged to obtain a fluorine-free and environmentally friendly oil repellent for paper.

[0010] Furthermore, in step (1), the reaction temperature is 80-90°C, the stirring speed is 150-200 rpm, and the reaction time is 1-2 hours; in step (2), the vacuum degree of the reaction system reaches -0.08 to -0.09 MPa, the reaction temperature is maintained at 70-80°C, and the reaction time is 30-60 minutes; in step (3), the rotation speed of the colloid mill is 2000-3000 rpm, and the dispersion time is 10-20 minutes; in step (4), the shear rate is 3000-5000 rpm, and the emulsification time is 15-30 minutes; in step (5), the evaporation temperature is 60-70°C, the vacuum degree is -0.06 to -0.08 MPa, and the concentration time is 1-2 hours.

[0011] The invention also provides application of a fluorine-free and environment-friendly oil-proofing agent for paper base in food packaging.

[0012] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. The present invention forms a highly efficient, environmentally friendly, fluorine-free oil-proof agent by rationally compounding components such as modified cellulose, gelatin, acrylate monomers, polyurethane prepolymers, modified nano-silica and polyether-modified siloxane. The fine preparation process with colloid mill dispersion, high shear emulsification and low-temperature concentration steps ensures uniform coating and long-term stability of the oil-proof agent on the surface of the paper-based material. In addition, the introduction of polyurethane prepolymers and polyether-modified siloxanes helps to enhance the adhesion and flexibility of the coating and reduce the risk of the coating falling off; the introduction of modified cellulose and nano-silica not only enhances the hydrophobicity and oil resistance of the coating, but also improves the mechanical strength and wear resistance of the coating, thereby enhancing the oil-proof effect.

[0013] 2. The present invention introduces long-chain alkyl groups through esterification to improve the hydrophobicity of cellulose, and grafts the esterified cellulose with methyl methacrylate, butyl acrylate and ammonium persulfate in dimethylformamide to improve the reactivity of cellulose and its compatibility with other components; the long-chain hydrocarbon group of stearic acid is adsorbed on the surface of nano-silica to reduce its surface energy, improve its dispersibility and compatibility with organic matrices, and interfacial polymerization of methyl methacrylate is carried out on the surface of modified nano-silica to form a polymer shell, which further enhances its hydrophobicity and binding force with the oil repellent system, thereby improving the dispersibility and stability of nano-silica in the oil repellent, and enhancing the hydrophobicity and oil resistance of the oil repellent. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 creative work.

[0015] Figure 1 A partial structural schematic diagram of a system for processing a fluorine-free and environmentally friendly oil-proofing agent for paper base according to the present invention is shown; Figure 2 Another part of the structural schematic diagram of the fluorine-free and environmentally friendly oil-proofing agent processing system for paper base of the present invention is shown.

[0016] Figure numerals: 1. atmospheric pressure reactor; 2. vacuum pump; 3. screw pump one; 4. vacuum reactor; 5. colloid mill; 6. screw pump two; 7. shear emulsification tank; 8. screw pump three; 9. temporary storage tank; 10. screw pump four; 11. three-effect falling film evaporator; 12. finished product tank. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention.

[0018] Example 1, see Figure 1-Figure 2 As shown, this embodiment provides a system for processing fluorine-free environmentally friendly oil-proofing agent for paper base, which is suitable for the processing method of fluorine-free environmentally friendly oil-proofing agent for paper base, including a normal pressure reactor 1, a vacuum reactor 4 and a shear emulsification tank 7. The bottom of the normal pressure reactor 1 is connected to the top of the vacuum reactor 4 through a screw pump 1 3, and the top of the vacuum reactor 4 is connected to a vacuum pump 2. The bottom of the vacuum reactor 4 is connected to a screw pump 2 6 through a colloid mill 5, and the screw pump 2 6 is connected to the top of the shear emulsification tank 7. The bottom of the shear emulsification tank 7 is connected to a temporary storage tank 9 through a screw pump 3 8, and the bottom of the temporary storage tank 9 is connected to a three-effect falling film evaporator 11 through a screw pump 4 10, and the discharge port of the three-effect falling film evaporator 11 is connected to a finished product tank 12.

[0019] The fluorine-free environmentally friendly oil-proofing agent processing system for paper base has the functions of main emulsion preparation, degassing and concentration, colloid grinding, emulsification, low-temperature concentration, storage and packaging, realizes the automatic processing of the fluorine-free environmentally friendly oil-proofing agent, and improves the stability of the fluorine-free environmentally friendly oil-proofing agent.

[0020] Example 2. This example discloses a fluorine-free, environmentally friendly oil-proof agent for paper, comprising the following components by weight: 30 kg of modified cellulose, 10 kg of gelatin, 6 kg of methyl methacrylate, 3 kg of butyl acrylate, 10 kg of polyether polyurethane, 10 kg of polyester polyurethane, 2 kg of modified nano-silica and 1 kg of polyether-modified siloxane; the modified cellulose is carboxymethyl cellulose modified by esterification and graft polymerization; the modified nano-silica is nano-silica modified by organic treatment and interfacial polymerization.

[0021] The preparation method of the modified cellulose comprises the following steps: S1, esterification: 1 kg of carboxymethyl cellulose was added to 6.25 L of anhydrous ethanol containing 250 g of caprylic anhydride and 250 g of stearic anhydride, 31.25 mL of 96 wt % sulfuric acid was added, and the reaction was stirred at 60 ° C for 2 hours, the pH was adjusted to 7 with 1 M NaOH solution, centrifuged, and then washed with water twice, and dried at 60 ° C to obtain esterified cellulose; S2. Graft polymerization: 100 g of esterified cellulose was dispersed in 1 L of dimethylformamide, and 50 g of methyl methacrylate, 50 g of butyl acrylate and 10 g of ammonium persulfate were added. The reaction temperature was stirred at 60° C. for 2 hours, and the mixture was centrifuged, washed twice with dimethylformamide, and dried at 60° C. to obtain graft copolymerized cellulose.

[0022] The preparation method of the nano silicon dioxide comprises the following steps: Q1. Pretreatment: 100 g of nano-silicon dioxide was dispersed in 1 L of water, and ultrasonic treatment was performed for 30 minutes. 16 g of stearic acid was added, and the mixture was stirred for 2 hours at a reaction temperature of 60°C to obtain a reaction suspension. Q2. Interfacial polymerization: add 16 g of methyl methacrylate and 1 g of benzoyl peroxide to the reaction suspension, the reaction temperature is 70°C, the reaction time is 2 hours, filter, wash twice with 75% ethanol, dry at 60°C, and obtain modified nano-silica.

[0023] See also Figure 1-Figure 2 As shown, a method for preparing a fluorine-free environmentally friendly oil-proof agent for paper base includes the following steps: (1) Preparation of the main emulsion: Add modified cellulose, gelatin, acrylate monomer, polyurethane prepolymer and nano-silica to a normal pressure reactor 1, and add polyether-modified siloxane at the same time, and stir to react. The reaction temperature is 80° C., the stirring speed is 150 rpm, the reaction time is 1 hour, and the mixture is naturally cooled to room temperature to obtain a preliminary oil repellent solution; (2) Degassing and concentration: The gas in the vacuum reactor 4 is extracted by the vacuum pump 2, and the preliminary oil repellent solution is transferred to the vacuum reactor 4 by the screw pump 3 for degassing and concentration. The vacuum degree of the reaction system reaches -0.08 MPa, the reaction temperature is maintained at 70°C, and the reaction time is 30 minutes to obtain a concentrated oil repellent solution; (3) Colloid mill: The concentrated oil repellent solution is finely dispersed by a colloid mill 5 at a rotation speed of 2000 rpm for a dispersion time of 10 minutes to obtain a finely dispersed oil repellent solution; (4) Emulsification stage: the finely dispersed oil repellent solution is transferred to the high shear emulsification tank 7 through the screw pump 2 6, and the solution is further dispersed and emulsified by the high shear force. The shear speed is 3000 rpm and the emulsification time is 15 minutes to obtain an emulsified oil repellent solution; the emulsified oil repellent solution is transferred to the temporary storage tank 9 through the screw pump 3 8; (5) Low temperature concentration: The finely dispersed oil repellent solution is transferred to the triple-effect falling film evaporator 11 through a screw pump 10 for low temperature continuous evaporation concentration. The evaporation temperature is 60°C, the vacuum degree is -0.06MPa, and the concentration time is 1 hour to obtain a stable oil repellent solution. (6) Storage and packaging: The stable oil-proofing agent solution is transferred to the finished product tank 12 and packaged to obtain the fluorine-free and environmentally friendly oil-proofing agent for paper base.

[0024] Example 3. This example discloses a fluorine-free, environmentally friendly oil-proof agent for paper, comprising the following components by weight: 40kg modified cellulose, 15kg gelatin, 12kg methyl methacrylate, 6kg butyl acrylate, 13kg polyether polyurethane, 13kg polyester polyurethane, 4kg modified nano-silica and 2kg polyether modified siloxane; the modified cellulose is carboxymethyl cellulose modified by esterification and graft polymerization; the modified nano-silica is nano-silica modified by organic treatment and interfacial polymerization.

[0025] The preparation method of the modified cellulose comprises the following steps: S1, esterification: 1 kg of carboxymethyl cellulose was added to 10 L of anhydrous ethanol containing 500 g of caprylic anhydride and 500 g of stearic anhydride, 50 mL of 97 wt % sulfuric acid was added, and the mixture was stirred for reaction at 70 ° C for 4 hours, the pH was adjusted to 7.2 with 1 M NaOH solution, and the mixture was centrifuged and then washed with water for 3 times, and dried at 63 ° C to obtain esterified cellulose; S2. Graft polymerization: 100 g of esterified cellulose was dispersed in 1 L of dimethylformamide, and 80 g of methyl methacrylate, 80 g of butyl acrylate and 40 g of ammonium persulfate were added. The stirring temperature for the reaction was 70° C. and the stirring time for the reaction was 4 hours. The mixture was centrifuged, washed with dimethylformamide for 3 times, and dried at 63° C. to obtain graft copolymerized cellulose.

[0026] The preparation method of the nano silicon dioxide comprises the following steps: Q1. Pretreatment: 100 g of nano-silicon dioxide was dispersed in 1 L of water, and ultrasonic treatment was performed for 40 minutes. 20 g of stearic acid was added, and the reaction was stirred for 3 hours at a reaction temperature of 63°C to obtain a reaction suspension. Q2. Interfacial polymerization: add 16 methyl methacrylate and 1 benzoyl peroxide to the reaction suspension, the reaction temperature is 73°C, the reaction time is 4 hours, filter, wash 3 times with 75% ethanol, dry at 63°C, and obtain modified nano-silica.

[0027] See also Figure 1-Figure 2 As shown, a method for preparing a fluorine-free environmentally friendly oil-proof agent for paper base includes the following steps: (1) Preparation of the main emulsion: Add modified cellulose, gelatin, acrylate monomer, polyurethane prepolymer and nano-silica to a normal pressure reactor 1, and add polyether-modified siloxane at the same time, and stir to react. The reaction temperature is 85° C., the stirring speed is 180 rpm, the reaction time is 2 hours, and the mixture is naturally cooled to room temperature to obtain a preliminary oil repellent solution. (2) Degassing and concentration: The gas in the vacuum reactor 4 is extracted by the vacuum pump 2, and the preliminary oil repellent solution is transferred to the vacuum reactor 4 by the screw pump 3 for degassing and concentration. The vacuum degree of the reaction system reaches -0.09 MPa, the reaction temperature is maintained at 80°C, and the reaction time is 50 minutes to obtain a concentrated oil repellent solution; (3) Colloid mill: The concentrated oil repellent solution is finely dispersed by a colloid mill 5 at a rotation speed of 2500 rpm for a dispersion time of 15 minutes to obtain a finely dispersed oil repellent solution; (4) Emulsification stage: the finely dispersed oil repellent solution is transferred to the high shear emulsification tank 7 through the screw pump 2 6, and the solution is further dispersed and emulsified by the high shear force. The shear speed is 4000 rpm and the emulsification time is 20 minutes to obtain an emulsified oil repellent solution. The emulsified oil repellent solution is transferred to the temporary storage tank 9 through the screw pump 3 8; (5) Low temperature concentration: The finely dispersed oil repellent solution is transferred to the triple-effect falling film evaporator 11 through a screw pump 10 for low temperature continuous evaporation concentration. The evaporation temperature is 65°C, the vacuum degree is -0.07 MPa, and the concentration time is 2 hours to obtain a stable oil repellent solution. (6) Storage and packaging: The stable oil-proofing agent solution is transferred to the finished product tank 12 and packaged to obtain the fluorine-free and environmentally friendly oil-proofing agent for paper base.

[0028] Example 4. This example discloses a fluorine-free, environmentally friendly oil-proof agent for paper, comprising the following components by weight: 50kg modified cellulose, 20kg gelatin, 12kg methyl methacrylate, 6kg butyl acrylate, 15kg polyether polyurethane, 15kg polyester polyurethane, 5kg modified nano-silica and 3kg polyether modified siloxane; the modified cellulose is obtained by modifying carboxymethyl cellulose through esterification and graft polymerization; the modified nano-silica is obtained by modifying nano-silica through organic treatment and interfacial polymerization.

[0029] The preparation method of the modified cellulose comprises the following steps: S1, esterification: 1 kg of carboxymethyl cellulose was added to 10 L of anhydrous ethanol containing 500 g of caprylic anhydride and 500 g of stearic anhydride, 50 mL of 98 wt % sulfuric acid was added, and the mixture was stirred for reaction at 80 ° C for 6 hours, the pH was adjusted to 7.5 with 1 M NaOH solution, and the mixture was centrifuged and then washed with water for 3 times, and dried at 65 ° C to obtain esterified cellulose; S2, graft polymerization: 200g of esterified cellulose was dispersed in 1L of dimethylformamide, 160g of methyl methacrylate, 160g of butyl acrylate and 50g of ammonium persulfate were added, the temperature of stirring reaction was 80°C, the stirring reaction time was 6 hours, centrifuged, washed with dimethylformamide 3 times, and dried at 65°C to obtain graft copolymerized cellulose; The preparation method of the nano silicon dioxide comprises the following steps: Q1. Pretreatment: 200 g of nano-silicon dioxide was dispersed in 1 L of water, and ultrasonic treatment was performed for 40 minutes. 40 g of stearic acid was added, and the reaction was stirred for 3 hours at a reaction temperature of 65°C to obtain a reaction suspension. Q2. Interfacial polymerization: add 40g methyl methacrylate and 2g benzoyl peroxide to the reaction suspension, the reaction temperature is 75°C, the reaction time is 4 hours, filter, wash with 75% ethanol 3 times, dry, the drying temperature is 65°C, and obtain modified nano-silica.

[0030] See also Figure 1-Figure 2 As shown, a method for preparing a fluorine-free environmentally friendly oil-proof agent for paper base includes the following steps: (1) Preparation of the main emulsion: Add modified cellulose, gelatin, acrylate monomer, polyurethane prepolymer and nano-silica to a normal pressure reactor 1, and add polyether-modified siloxane at the same time, and stir to react. The reaction temperature is 90° C., the stirring speed is 200 rpm, the reaction time is 2 hours, and the reaction is naturally cooled to room temperature to obtain a preliminary oil repellent solution; (2) Degassing and concentration: The gas in the vacuum reactor 4 is extracted by the vacuum pump 2, and the preliminary oil repellent solution is transferred to the vacuum reactor 4 by the screw pump 3 for degassing and concentration. The vacuum degree of the reaction system reaches -0.09 MPa, the reaction temperature is maintained at 80°C, and the reaction time is 60 minutes to obtain a concentrated oil repellent solution; (3) Colloid mill: The concentrated oil repellent solution is finely dispersed by a colloid mill 5 at a rotation speed of 3000 rpm for a dispersion time of 20 minutes to obtain a finely dispersed oil repellent solution; (4) Emulsification stage: the finely dispersed oil repellent solution is transferred to the high shear emulsification tank 7 through the screw pump 2 6, and the solution is further dispersed and emulsified by the high shear force. The shear speed is 5000 rpm and the emulsification time is 30 minutes to obtain an emulsified oil repellent solution. The emulsified oil repellent solution is transferred to the temporary storage tank 9 through the screw pump 3 8; (5) Low temperature concentration: The finely dispersed oil repellent solution is transferred to the triple-effect falling film evaporator 11 through a screw pump 10 for low temperature continuous evaporation concentration. The evaporation temperature is 70°C, the vacuum degree is -0.08 MPa, and the concentration time is 2 hours to obtain a stable oil repellent solution. (6) Storage and packaging: The stable oil-proofing agent solution is transferred to the finished product tank 12 and packaged to obtain the fluorine-free and environmentally friendly oil-proofing agent for paper base.

[0031] Comparative Example 1: Comparative Example 1 Compared with Example 3, in the preparation process of the fluorine-free and environmentally friendly oil-proof agent for paper base in Comparative Example 1, no modified cellulose is added, and other conditions remain unchanged.

[0032] Comparative Example 2: Comparative Example 2 Compared with Example 3, in the preparation process of the fluorine-free and environmentally friendly oil-proof agent for paper base in Comparative Example 2, no modified nano-silica is added, and other conditions remain unchanged.

[0033] Comparative Example 3: Comparative Example 3 Compared with Example 3, in the preparation process of the fluorine-free and environmentally friendly oil-proofing agent for paper base in Comparative Example 3, the high shear force emulsification stage is not performed, and other conditions remain unchanged.

[0034] Comparative Example 4: Comparative Example 4 Compared with Example 3, in the preparation process of the fluorine-free environmentally friendly oil-proofing agent for paper base in Comparative Example 4, fine dispersion by colloid mill is not performed, and other conditions remain unchanged.

[0035] Experimental example The performance of the fluorine-free environmentally friendly oil-proof agent for paper prepared in Examples 2-4 and Comparative Examples 1-4 was tested. The fluorine-free environmentally friendly oil-proof agent for paper prepared in Examples 2-4 and Comparative Examples 1-4 was respectively applied to the paper base material by a coating roller to form a coating, and then directly heat-sealed to form a disposable paper bowl. The prepared disposable paper bowl was subjected to the following performance tests: The oil-proof performance was tested according to GB / T 24218.2-2009, the oil penetration time was observed, and the contact angle of the oil drop on the paper surface was measured using a contact angle meter; the mechanical properties were tested according to GB / T 1720-1989, the tape stripping method was used to evaluate the adhesion between the coating and the paper base, and the wear resistance of the coating was measured using a Taber abrasion tester; the tensile strength was tested according to GB / T 24497-2009 and the VOC content was tested according to GB / T 23344-2009. The results are shown in Table 1: Table 1

[0036] According to the test results in Table 1, it can be seen that the grease penetration time, contact angle, tensile strength, adhesion and wear resistance of Examples 2-4 of the present invention are significantly improved, and the VOC content is significantly reduced. Comparison of Examples 2-4 with Comparative Examples 1-4 shows that the addition of modified cellulose, modified nano-silica, the high shear force emulsification stage and the fine dispersion of the colloid mill can significantly improve the oil resistance, mechanical properties, tensile strength and chemical stability.

[0037] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

[0038] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to only specific implementation methods. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A fluorine-free environmentally friendly oil-proofing agent for paper base, characterized in that: The invention comprises the following components in parts by weight: 30-50 parts of modified cellulose, 10-20 parts of gelatin, 9-18 parts of acrylate monomers, 20-30 parts of polyurethane prepolymers, 2-5 parts of modified nano silicon dioxide and 1-3 parts of polyether modified siloxane; the modified cellulose is obtained by modifying carboxymethyl cellulose through esterification and graft polymerization; the acrylate monomer is a mixture of methyl methacrylate and butyl acrylate, the mass ratio of methyl methacrylate to butyl acrylate is 2:1; the polyurethane prepolymer is a mixture of polyether polyurethane and polyester polyurethane, the mass ratio of polyether polyurethane to polyester polyurethane is 1:1; the modified nano silicon dioxide is obtained by modifying nano silicon dioxide through organic treatment and interfacial polymerization.

2. The fluorine-free environmentally friendly oil-proofing agent for paper base according to claim 1, characterized in that: The preparation method of the modified cellulose comprises the following steps: S1, esterification: adding carboxymethyl cellulose to solution 1, adding sulfuric acid, stirring the reaction, after the reaction is completed, adjusting the pH with NaOH solution, centrifuging, then washing with water, and drying to obtain esterified cellulose; S2. Graft polymerization: Disperse the esterified cellulose in dimethylformamide, add methyl methacrylate, butyl acrylate and ammonium persulfate, stir and react, and after reaction, centrifuge, wash and dry to obtain graft copolymerized cellulose.

3. The fluorine-free and environmentally friendly oil-proofing agent for paper base according to claim 2, characterized in that: Solution 1 in S1 is prepared by dissolving caprylic anhydride and stearic anhydride in anhydrous ethanol in a mass ratio of 1:1, the mass concentration of solution 1 is 8-10wt%, the mass ratio of carboxymethyl cellulose to anhydride is 1-2:1, the mass concentration of sulfuric acid is 96-98%, the volume ratio of sulfuric acid to anhydrous ethanol is 1:200, the stirring reaction temperature is 60-80°C, the stirring reaction time is 2-6 hours, the concentration of NaOH solution is 1M, the pH is adjusted to 7-7.5, washed with water 2-3 times, and dried at 60-65°C.

4. The fluorine-free and environmentally friendly oil-proofing agent for paper base according to claim 2, characterized in that: The mass volume ratio of esterified cellulose to dimethylformamide in S2 is 10-20:100 g / mL, the mass ratio of esterified cellulose to methyl methacrylate is 1:0.5-0.8, the mass ratio of methyl methacrylate to butyl acrylate is 1:1, the mass concentration of ammonium persulfate is 1-5wt%, the stirring reaction temperature is 60-80°C, the stirring reaction time is 2-6 hours, washed with dimethylformamide 2-3 times, and dried at 60-65°C.

5. The fluorine-free and environmentally friendly oil-proofing agent for paper base according to claim 1, characterized in that: The preparation method of the nano silicon dioxide comprises the following steps: Q1. Pretreatment: disperse nano-silicon dioxide in water, perform ultrasonic treatment, add stearic acid, stir and react to obtain a reaction suspension; Q2. Interfacial polymerization: Add methyl methacrylate and benzoyl peroxide to the reaction suspension, stir to react, and after completion, filter, wash, and dry to obtain modified nano-silica.

6. The fluorine-free and environmentally friendly oil-proofing agent for paper base according to claim 5, characterized in that: The mass volume ratio of nano-silicon dioxide to water in Q1 is 10-20:100 g / mL, and the ultrasonic treatment is carried out for 30-40 minutes. The mass ratio of nano-silicon dioxide to stearic acid is 5:0.8-1, and the reaction is stirred for 2-3 hours. The reaction temperature is 60-65°C.

7. The fluorine-free and environmentally friendly oil-proofing agent for paper base according to claim 5, characterized in that: In Q2, the mass ratio of nano-silicon dioxide to methyl methacrylate is 5:0.8-1, the mass ratio of nano-silicon dioxide to benzoyl peroxide is 100:1, the reaction temperature is 70-75°C, the reaction time is 2-4 hours, it is washed with 75% ethanol 2-3 times, and the drying temperature is 60-65°C.

8. A method for preparing a fluorine-free environmentally friendly oil-proofing agent for paper base, characterized in that: The following steps are involved: Preparation of the main emulsion: Add modified cellulose, gelatin, acrylate monomer, polyurethane prepolymer and nano-silica to a normal pressure reactor (1), and add polyether-modified siloxane at the same time, stir and react, and after the reaction is completed, naturally cool to room temperature to obtain a preliminary oil-proofing agent solution; Degassing and concentration: the gas in the vacuum reactor (4) is extracted by a vacuum pump (2), and the preliminary oil repellent solution is transferred to the vacuum reactor (4) by a screw pump (3), and degassing and concentrating are performed to obtain a concentrated oil repellent solution; Colloid mill: the concentrated oil repellent solution is finely dispersed by passing it through a colloid mill (5) to obtain a finely dispersed oil repellent solution; Emulsification stage: the finely dispersed oil-proofing agent solution is transferred to the high shear emulsification tank (7) through the screw pump 2 (6), and the solution is further dispersed and emulsified by the high shear force to obtain an emulsified oil-proofing agent solution; the emulsified oil-proofing agent solution is transferred to the temporary storage tank (9) through the screw pump 3 (8); Low temperature concentration: the finely dispersed oil repellent solution is transferred to a three-effect falling film evaporator (11) through a screw pump (10) for low temperature continuous evaporation concentration to obtain a stable oil repellent solution; Storage and packaging: The stable oil-proofing agent solution is transferred to a finished product tank (12) and packaged to obtain a fluorine-free and environmentally friendly oil-proofing agent for paper base.

9. The method for preparing a fluorine-free environmentally friendly oil-proofing agent for paper base according to claim 8, characterized in that: The reaction temperature for the preparation of the main emulsion is 80-90°C, the stirring speed is 150-200rpm, and the reaction time is 1-2 hours; the vacuum degree of the degassed and concentrated reaction system reaches -0.08 to -0.09MPa, the reaction temperature is maintained at 70-80°C, and the reaction time is 30-60 minutes; the rotation speed of the colloid mill is 2000-3000rpm, and the dispersion time is 10-20 minutes; the shear rate in the emulsification stage is 3000-5000rpm, and the emulsification time is 15-30 minutes; the evaporation temperature of the low-temperature concentration is 60-70°C, the vacuum degree is -0.06 to -0.08MPa, and the concentration time is 1-2 hours.

10. Use of the fluorine-free and environmentally friendly oil-proof agent for paper base according to claims 1-9 in food packaging.

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