Biomass-based water-resistant and oil-resistant packaging paper and preparation method thereof

Abstract

The application discloses a biomass-based water-resistant and oil-resistant packaging paper and a preparation method thereof. The biomass-based water-resistant and oil-resistant packaging paper provided by the application takes Sargassum fusiforme, cellulose derivatives, lignin and the like as main raw materials, all of which are natural biomass-based polymers. The prepared water-resistant and oil-resistant paper is fluorine-free, green and environment-friendly, can be completely biodegraded, is harmless to the environment and human bodies, and has a simple preparation method and can be used to realize industrialized production.

Description

Technical Field

[0001] The present invention relates to the field of biopolymers, and in particular to a biomass-based water-resistant and oil-resistant packaging paper and a preparation method thereof. Background Art

[0002] Paper-based packaging materials are one of the most promising materials for replacing disposable plastic products and solving the problem of "white pollution" due to their advantages such as lightness, biodegradability, recyclability and mechanical flexibility. So far, the market share of paper-based packaging materials accounts for about 50% of the total packaging industry. However, the surface fibers of paper-based materials are hydrophilic and porous, resulting in poor water resistance and oil resistance. In addition, the adhesion of water and oil on the surface of paper-based materials will seriously affect the mechanical properties of paper, which severely limits the daily use of paper. At present, some specially treated paper-based materials on the market have both water and oil resistance, which effectively solves the problem of poor barrier properties of paper used for food packaging. Water-resistant and oil-resistant packaging paper is a kind of paper that resists the penetration of grease and water. It is often used to package foods with grease and high water content, such as hamburgers, cakes, traditional Chinese fast food, etc.

[0003] Since paper products themselves are not resistant to water and oil, in order to achieve the purpose of water and oil resistance, most paper products in the early days were covered with plastic film when used. However, the materials of plastic film, such as low-density polyethylene (LDPE), polyvinyl chloride (PVC), polyethylene terephthalate (PET), etc., cannot degrade on their own after being discarded. Even if incineration is adopted, a large amount of waste gas will be generated during the combustion process, which becomes a major source of environmental pollution. Moreover, the raw materials of these plastic films come from petroleum, which is a non-renewable resource. The large-scale use of plastic film will aggravate the energy crisis. Later, the use of fluorine coating in wrapping paper can achieve good oil resistance, but the application of fluorine coating in food packaging has certain risks. Moreover, after the fluorine-coated wrapping paper is discarded, it will release fluorine-containing organic matter during the compost decomposition process, polluting the soil and affecting people's health.

[0004] As people's awareness of environmental protection and physical health continues to increase, biodegradable materials have gradually become a research hotspot to replace traditional plastic materials due to their environmental protection, non-toxicity and regeneration properties. However, these biodegradable materials cannot truly achieve the dual effects of environmental protection and economy. For example, polylactic acid (PLA) has good biodegradability and mechanical properties, but it is hard and brittle at room temperature, with extremely low elongation at break and impact strength; polyvinyl alcohol (PVA) can be used by bacteria as a carbon source, and has excellent oil resistance and gas barrier properties, but its production process is complex and costly; polybutylene terephthalate (PBAT) has good flexibility, but its heat sealing properties are poor, its texture is soft, and it is easy to deform when stretched, which greatly limits the promotion and application of environmentally friendly biodegradable materials in the packaging field. Summary of the Invention

[0005] The purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art and to provide a biomass-based water-resistant and oil-resistant packaging paper.

[0006] Another object of the present invention is to provide a method for preparing the above-mentioned biomass-based water-resistant and oil-resistant packaging paper.

[0007] The purpose of the present invention is achieved through the following technical solutions:

[0008] A method for preparing biomass-based water-resistant and oil-resistant packaging paper comprises the following steps:

[0009] (1) impregnating base paper with a calcium chloride solution having a concentration of 1 to 3% for 4 to 10 minutes, and drying to obtain pretreated base paper;

[0010] (2) Preparation of nanocellulose using biomass raw materials;

[0011] (3) adding sodium dodecyl sulfate to anhydrous ethanol, stirring and heating at 50-70° C. for 30-50 min, then adding the nanocellulose obtained in step (2), continuing to stir and heat the reaction, washing, and ultrasonicating to obtain modified sulfonated nanocellulose;

[0012] (4) adding ethyl cellulose to anhydrous ethanol, stirring and heating at 30-50° C. for 20-40 minutes, then adding the modified sulfonated nanocellulose obtained in step (3) and continuing to stir and heat for 20-40 minutes to obtain an oil-resistant solution;

[0013] (5) adding alkali lignin to anhydrous ethanol, stirring and heating the mixture at 40-60°C for 40-80 minutes, then adding water and continuing stirring and heating the mixture for 20-40 minutes, collecting the supernatant, centrifuging the mixture at 4000-6000 rpm for 10-30 minutes, and removing the ethanol by rotary evaporation to obtain lignin nanoparticles;

[0014] (6) adding the lignin nanoparticles prepared in step (5), octadecylamine, and ferulic acid to anhydrous ethanol, stirring and heating at 50-70° C. for 3-5 h, cooling, filtering, and drying to obtain modified lignin nanoparticles;

[0015] (7) adding polyvinyl butyral to anhydrous ethanol, stirring and heating at 40-60° C. for 30-50 minutes, then adding the modified lignin nanoparticles obtained in step (6), and continuing to stir and heat for 20-40 minutes to obtain an aqueous solution-resistant nanoparticle;

[0016] (8) stirring and mixing the oil-resistant solution obtained in step (4) and the water-resistant aqueous solution obtained in step (7) for 20 to 40 minutes, and ultrasonically treating to obtain a water-resistant and oil-resistant composite solution;

[0017] (9) coating the water and oil resistant composite solution obtained in step (8) on the pretreated raw paper obtained in step (1), drying to obtain a biomass-based water and oil resistant packaging paper.

[0018] The raw paper in step (1) is paper with rough surface made of raw wood pulp.

[0019] The drying condition in step (1) is drying at 30-50℃ for 5-20min.

[0020] The biomass raw material in step (2) is cellulose-rich biomass raw material; preferably conifer pulp or Sargassum fusiforme; more preferably Sargassum fusiforme.

[0021] When the biomass raw material is conifer pulp, the preparation method of nanocellulose is as follows:

[0022] 20g bleached conifer pulp is added to a solution obtained by dissolving 0.05g TEMPO, 0.5g NaBr and 50mL NaClO in 500mL deionized water, the pH value of the reaction system is adjusted to 10 by 0.1mol / L HCl and NaOH, and then homogenized at 180MPa for 15 times, and conifer pulp nanocellulose is obtained by filtration.

[0023] When the biomass raw material is Sargassum fusiforme, the preparation method of nanocellulose is as follows:

[0024] Sargassum fusiforme dry product is soaked in water, soaked Sargassum fusiforme is uniformly mixed in 20wt% Na2CO3 solution for 1h, dried, washed, added to 3wt% acetic acid solution and reacted for 2h, then 30wt% H2O2 solution is added and reacted for 2h, washed, added with deionized water, then homogenized at 200MPa for 20 times, and Sargassum fusiforme nanocellulose is obtained by filtration.

[0025] The mass ratio of sodium dodecyl sulfonate to nanocellulose in step (3) is 1-2:1-2; preferably 2:1.

[0026] The ratio of anhydrous ethanol, ethyl cellulose and modified sulfonated nanocellulose in step (4) is 100mL:4-10g:2-6g; preferably 100mL:7g:3g.

[0027] The mass ratio of lignin nanoparticles, octadecylamine and ferulic acid in step (6) is 2-3:1-2:1-2; preferably 5:3:2.

[0028] The ratio of anhydrous ethanol, polyvinyl butyral and modified lignin nanoparticles in step (7) is 100mL:5-20g:1-2g; preferably 100mL:10g:1g.

[0029] The mass ratio of the oil-resistant solution to the water-resistant solution in step (8) is 1-3:1-3; preferably 1:1.

[0030] The coating in step (9) is performed using a roller coater.

[0031] The coating conditions of step (9) are as follows: a coating rate of 4 to 6 cm / s and a coating amount of 6 to 10 g / m 2 .

[0032] The drying condition of step (9) is drying at 40-60° C. for 20-40 minutes.

[0033] The filtration was performed using filter paper with a pore size of 0.3 μm.

[0034] Unless otherwise specified, the solutions described above are all solutions prepared with water as solvent.

[0035] A biomass-based water-resistant and oil-resistant packaging paper is prepared according to the above preparation method.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] (1) A method for preparing a biomass-based water-resistant and oil-resistant packaging paper is provided, wherein the base paper is pretreated with a calcium chloride solution, and a homemade modified sulfonated Sargassum fusiformis nanocellulose solution and an ethyl cellulose solution are compounded to prepare an oil-resistant coating, and an oleophobic group (SO4 2- ,-COO - ), combined with ethyl cellulose to form an oleophobic film on the surface of the paper, thereby achieving the purpose of filling the pores on the surface of the paper and significantly improving the oil resistance of the paper; and Ca 2+ -COO in Sargassum fusiformis nanocellulose - A cross-linking effect occurs, which makes the oil-resistant coating tightly bonded to the paper, and improves the mechanical properties of the paper.

[0038] (2) The homemade modified lignin nanoparticle solution and polyvinyl butyral solution were compounded to prepare a water-resistant coating, which was applied on the surface of the base paper, giving the paper excellent water resistance and further improving the mechanical properties of the paper.

[0039] (3) The biomass-based water-resistant and oil-resistant packaging paper provided by the present invention uses sea lettuce, cellulose derivatives, lignin, etc. as main raw materials, all of which are natural biomass-based polymers. The prepared water-resistant and oil-resistant paper is fluorine-free, green and environmentally friendly, completely biodegradable, harmless to the environment and human body, and the preparation method is simple and can be used to realize industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Fig. 1This is the oil resistance test result in Example 5.

[0041] Fig. 2 This is the water resistance test result in Example 5.

[0042] Fig. 3 This is the tensile strength test result in Example 5.

[0043] Fig. 4 This is the air permeability test result in Example 5.

[0044] Fig. 5 This is the water vapor transmission rate test result in Example 5.

[0045] Fig. 6 This is the degradation performance test result in Example 5.

[0046] Fig. 7 These are photographs of paper prepared in Example 1 and untreated paper; the left picture is untreated paper, and the right picture is paper prepared in Example 1. DETAILED DESCRIPTION

[0047] The present invention will be described in further detail below with reference to the embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0048] If specific experimental conditions are not specified in the following embodiments, conventional experimental conditions or those recommended by the reagent company will generally be used. Materials and reagents used were commercially available unless otherwise specified.

[0049] Source of raw materials:

[0050] Base paper: purchased from Guangxi Hezhou Red Star Paper Co., Ltd., the product name is white kraft paper, the product weight is 40g / m 2 ;

[0051] Sargassum fusiforme: purchased from Rongcheng Three Penguins E-Commerce Co., Ltd.

[0052] Ethyl cellulose: purchased from Guangzhou Huayu Biotechnology Co., Ltd.

[0053] Alkali lignin: purchased from Wuhan Lanabai Pharmaceutical Chemical Co., Ltd.

[0054] Polyvinyl butyral: purchased from Guangdong Fangxin Biotechnology Co., Ltd.

[0055] Example 1

[0056] A method for preparing biomass-based water-resistant and oil-resistant packaging paper comprises the following steps:

[0057] (1) Take calcium chloride into deionized water, mix uniformly, get 2.0% calcium chloride solution; Put the base paper into 100 mL calcium chloride solution, soak for 6 min, then put the paper into the vacuum drying oven, dry at 40℃ for 10 min, get the calcium chloride pretreated base paper.

[0058] (2) Put 400g of Sargassum fusiforme (absolute dry mass) into 2L deionized water and soak for 24h, at the same time, prepare 20% Na2CO3 solution, put the soaked Sargassum fusiforme into 2L Na2CO3 solution and mix uniformly for 1h, then put it into the oven at 60℃ and dry for 24h; After drying, wash the Sargassum fusiforme with deionized water, put it into 500mL acetic acid solution with 3% mass percentage concentration, react for 2h, then add 50mL 30% H2O2 solution, react for 2h, then wash with deionized water for 20 times. Finally, add 500mL deionized water to the Sargassum fusiforme product, then homogenize at 200MPa for 20 times, finally perform suction filtration at-0.09MPa pressure, get pure Sargassum fusiforme nanocellulose.

[0059] (3) Take 100mL anhydrous ethanol and heat at 60℃ (closed container), add 10g sodium dodecyl sulfonate, stir for 40min to prepare sodium dodecyl sulfonate solution; Put 5g Sargassum fusiforme nanocellulose into the sodium dodecyl sulfonate solution, continue to heat and stir for 60min for modification reaction, after the reaction is completed, perform suction filtration at-0.09MPa pressure (filter paper pore size 0.3μm), get modified nanocellulose. Finally, wash the modified nanocellulose with deionized water for 10 times, and ultrasonic treat at 200W power for 30min, get pure modified sulfonated nanocellulose.

[0060] (4) Take 100mL anhydrous ethanol and heat at 40℃, add 7g ethyl cellulose, stir for 30min to get ethyl cellulose solution, then add 3g modified sulfonated nanocellulose prepared in step (3), continue to heat and stir for 30min, prepare oil resistant solution.

[0061] (5) Take 300 mL of anhydrous ethanol and heat it at 50 ° C, add 20 g of alkali lignin into it, stir for 60 minutes, and after sufficient reaction, add 100 mL of deionized water and continue stirring for 30 minutes. Collect the supernatant and treat it in a high-speed centrifuge at 5000 rpm for 20 minutes, then use a rotary evaporator at 200 rpm for 30 minutes to remove ethanol to obtain lignin nanoparticles; take 5 g of lignin nanoparticles, 3 g of octadecylamine and 2 g of ferulic acid in 300 mL of ethanol solution, heat and stir at 60 ° C for 4 hours, wait for the sample to cool after sufficient reaction, filter it with a filter with a pore size of 0.3 μm, and dry it for 12 hours to obtain modified lignin nanoparticles.

[0062] (6) 300 mL of anhydrous ethanol was heated at 50 °C, 30 g of polyvinyl butyral was added thereto, and the mixture was stirred for 40 min to obtain a polyvinyl butyral solution. 3 g of modified lignin nanoparticles was then added thereto, and the mixture was heated and stirred for 30 min to obtain an aqueous solution.

[0063] (7) 50 g of the oil-resistant solution and 50 g of the water-resistant solution were mixed, stirred on a magnetic stirrer for 30 min, and then ultrasonically treated at a power of 200 W for 20 min to obtain a uniformly mixed water-resistant and oil-resistant composite solution. The composite solution was then uniformly coated on the surface of the base paper prepared in step (1) on a roller coater at a coating rate of 5 cm / s and a coating amount of 8 g / m 2 Finally, the paper is placed in a vacuum drying oven at a drying temperature of 50° C. and a drying time of 30 minutes to obtain the biomass-based water-resistant and oil-resistant packaging paper.

[0064] Example 2

[0065] A method for preparing biomass-based water-resistant and oil-resistant packaging paper comprises the following steps:

[0066] (1) Calcium chloride is added to deionized water and mixed uniformly to obtain a calcium chloride solution with a mass concentration of 1.0%; base paper is immersed in 100 mL of the calcium chloride solution for 8 minutes, and then the paper is placed in a vacuum drying oven and dried at 50° C. for 5 minutes to obtain base paper pretreated with calcium chloride.

[0067] (2) 300g of seaweed was soaked in 2L of deionized water for 36 hours. At the same time, a 20% mass concentration of Na2CO3 solution was prepared. The soaked seaweed was placed in the 2L Na2CO3 solution and evenly mixed for 1 hour. Then, it was placed in a 70°C oven and dried for 24 hours. The dried seaweed was fully washed with deionized water and placed in 500mL of 3% mass concentration of acetic acid solution. After fully reacting for 2 hours, 50mL of 30% mass concentration of H2O2 solution was added. After reacting for 2 hours, it was fully washed with deionized water 15 times. Finally, deionized water was added to the seaweed product, and then homogenized at 200MPa for 20 times to obtain pure seaweed nanocellulose.

[0068] (3) 100 mL of anhydrous ethanol was heated at 60 °C, 5 g of sodium dodecyl sulfate was added thereto, and the mixture was stirred for 40 min to obtain a sodium dodecyl sulfate solution; 5 g of Sargassum fusiformis nanocellulose was added to the sodium dodecyl sulfate solution, and the mixture was heated and stirred for 60 min to carry out the modification reaction. After the reaction was completed, the mixture was filtered under a pressure of -0.09 MPa (filter paper pore size 0.3 μm) to obtain modified nanocellulose. The modified nanocellulose was then washed 20 times with deionized water and ultrasonically treated at a power of 200 W for 40 min to obtain pure modified sulfonated nanocellulose.

[0069] (4) Take 100 mL of anhydrous ethanol and heat it at 40° C., add 8 g of ethyl cellulose thereto, and stir for 30 minutes to obtain an ethyl cellulose solution. Then, add 2 g of the modified sulfonated nanocellulose prepared in step (3) thereto, continue heating and stirring for 30 minutes, and obtain an oil-resistant solution.

[0070] (5) Take 300 mL of anhydrous ethanol and heat it at 50 ° C, add 15 g of alkali lignin into it, stir for 60 minutes, and after sufficient reaction, add 100 mL of deionized water and continue stirring for 30 minutes. Collect the supernatant and treat it in a high-speed centrifuge at 5000 rpm for 20 minutes, then use a rotary evaporator at 200 rpm for 30 minutes to remove ethanol to obtain lignin nanoparticles; take 5 g of lignin nanoparticles, 4 g of octadecylamine and 2 g of ferulic acid in 300 mL of ethanol solution, heat and stir at 60 ° C for 4 hours, wait for the sample to cool after sufficient reaction, filter it with a filter with a pore size of 0.3 μ, and dry it for 24 hours to obtain modified lignin nanoparticles.

[0071] (6) 300 mL of ethanol was heated at 50 °C, 35 g of polyvinyl butyral was added thereto, and the mixture was stirred for 40 min to obtain a polyvinyl butyral solution. 4 g of modified lignin nanoparticles was then added thereto, and the mixture was heated and stirred for 30 min to obtain an aqueous solution.

[0072] (7) Take 60 g of oil-resistant solution and 40 g of water-resistant solution, stir for 30 min on a magnetic stirrer, then perform ultrasonic treatment for 20 min at a power of 200 W, to obtain a uniformly mixed water-resistant and oil-resistant composite solution. Then, uniformly coat the composite solution on the surface of the base paper prepared in step (1) on a roll coater at a coating speed of 6 cm / s and a coating amount of 9 g / m 2 Finally, place the paper in a vacuum drying oven, dry at a temperature of 50℃ for 30 min, to obtain the biomass-based water-resistant and oil-resistant packaging paper.

[0073] Example 3

[0074] A method for preparing a biomass-based water-resistant and oil-resistant packaging paper, comprising the following steps:

[0075] (1) Add calcium chloride to deionized water and mix uniformly to obtain a calcium chloride solution with a mass concentration of 3.0%. Put the base paper into 100 mL of the calcium chloride solution and immerse for 6 min, then place the paper in a vacuum drying oven and dry at 30℃ for 10 min, to obtain the base paper pretreated with calcium chloride.

[0076] (2) Put 200 g of Sargassum into 2 L of deionized water and soak for 24 h. Meanwhile, prepare a Na2CO3 solution with a mass concentration of 20%. Put the soaked Sargassum into 2 L of the Na2CO3 solution and mix uniformly for 1 h, then place it in an oven at 60℃ and dry for 24 h. Wash the dried Sargassum with deionized water, then put it into 500 mL of an acetic acid solution with a mass percentage concentration of 3% and react for 2 h. Then, add 50 mL of a H2O2 solution with a mass concentration of 30% and react for 2 h. Finally, wash the product with deionized water for 20 times. Then, add deionized water to the Sargassum product and homogenize at 200 MPa for 20 times, to obtain pure Sargassum nanocellulose.

[0077] (3) Heat 100 mL of anhydrous ethanol at 60℃, then add 20 g of sodium dodecyl sulfate to the ethanol and stir for 40 min to obtain a sodium dodecyl sulfate solution. Then, add 10 g of Sargassum nanocellulose to the sodium dodecyl sulfate solution and continue to heat and stir for 60 min for modification reaction. After the reaction is completed, perform suction filtration at a pressure of -0.09 MPa (filter paper pore size 0.3 μm) to obtain modified nanocellulose. Then, wash the modified nanocellulose with deionized water for 20 times and perform ultrasonic treatment at a power of 200 W for 40 min, to obtain pure modified sulfonated nanocellulose.

[0078] (4) Take 100 mL of ethanol heated at 40℃, add 10 g of ethyl cellulose to it, stir for 30 min to obtain an ethyl cellulose solution, then add 5 g of modified sulfonated nanocellulose prepared in step (3) to it, continue to heat and stir for 30 min to prepare an oil-resistant solution.

[0079] (5) Take 300 mL of anhydrous ethanol heated at 50℃, add 20 g of alkali lignin to it, stir for 60 min, then add 100 mL of deionized water and continue to stir for 30 min, collect the supernatant and treat it in a high-speed centrifuge at 5000 rpm for 20 min, then use a rotary evaporator to treat it at 200 rpm for 30 min to remove ethanol, and prepare lignin nanoparticles; take 5 g of lignin nanoparticles, 3 g of octadecylamine and 2 g of ferulic acid in a 300 mL ethanol solution, heat and stir at 60℃ for 4 h, fully react, then cool the sample, filter it with a filter screen with a pore size of 0.3 μ, dry it for 12 h to prepare modified lignin nanoparticles.

[0080] (6) Take 300 mL of anhydrous ethanol heated at 50℃, add 30 g of polyvinyl butyral to it, stir for 40 min to obtain a polyvinyl butyral solution, then add 6 g of modified lignin nanoparticles to it, continue to heat and stir for 30 min to prepare a water-resistant solution.

[0081] (7) Take 40 g of the oil-resistant solution and 60 g of the water-resistant solution to perform compounding, stir on a magnetic stirrer for 30 min, then perform ultrasonic treatment at a power of 200 W for 20 min to prepare a uniformly mixed water-resistant and oil-resistant composite solution, then uniformly coat the composite solution on the surface of the base paper prepared in step (1) on a roll coater, the coating speed is 6 cm / s, and the coating amount is 10 g / m 2 , finally put the paper into a vacuum drying oven, the drying temperature is 50℃, and the drying time is 30 min, to prepare the biomass-based water-resistant and oil-resistant packaging paper.

[0082] Example 4

[0083] A method for preparing a biomass-based water-resistant and oil-resistant packaging paper, comprising the following steps:

[0084] (1) Take calcium chloride and add it to deionized water to obtain a calcium chloride solution with a mass concentration of 2.0%; put the base paper into 100 mL of the calcium chloride solution and immerse it for 5 min, then put the paper into a vacuum drying oven and dry it at 40℃ for 10 min to obtain a calcium chloride pretreated base paper.

[0085] (2) Put 400g of Sargassum into 2L of deionized water and soak for 24h, and prepare a Na2CO3 solution with a mass concentration of 20%. Put the soaked Sargassum into 2L of the Na2CO3 solution and mix evenly for 1h, and then put it into an oven at 60℃ and dry for 24h. After drying, the Sargassum is washed with deionized water, put into 500mL of an acetic acid solution with a mass percentage concentration of 3%, and fully reacted for 2h. Then, 50mL of H2O2 solution with a mass concentration of 30% is added, and reacted for 2h. After reaction, the product is washed with deionized water for 20 times. Finally, deionized water is added to the Sargassum product, and then homogenized at 200MPa for 20 times to obtain pure Sargassum nanocellulose.

[0086] (3) Take 100mL of anhydrous ethanol and heat it at 60℃, and then add 10g of sodium dodecyl sulfate to it, and stir for 40min to prepare a sodium dodecyl sulfate solution. Then, put 5g of Sargassum nanocellulose into the sodium dodecyl sulfate solution, and continue to heat and stir for 60min for modification reaction. After reaction, perform suction filtration at a pressure of -0.09MPa (filter paper pore size 0.3μm) to obtain modified nanocellulose. Then, wash the modified nanocellulose with deionized water for 10 times and ultrasonic treatment at 200W power for 30min to obtain pure modified sulfonated nanocellulose.

[0087] (4) Take 100mL of anhydrous ethanol and heat it at 40℃, and then add 7g of ethyl cellulose to it, and stir for 30min to obtain an ethyl cellulose solution. Then, add 3g of the modified sulfonated nanocellulose prepared in step (3) to it, and continue to heat and stir for 30min to prepare an oil-resistant solution.

[0088] (5) Take 300mL of anhydrous ethanol and heat it at 50℃, and then add 20g of alkali lignin to it, and stir for 60min. After reaction, add 100mL of deionized water and continue to stir for 30min. Collect the supernatant and treat it in a high-speed centrifuge at 5000rpm for 20min. Then, use a rotary evaporator to remove ethanol at 200rpm for 30min to prepare lignin nanoparticles. Take 5g of lignin nanoparticles, 3g of octadecylamine and 2g of ferulic acid, and add them to 300mL of an ethanol solution, and heat and stir at 60℃ for 4h for full reaction. After cooling the sample, perform filtration treatment using a filter screen with a pore size of 0.3μ. After drying for 12h, modified lignin nanoparticles are prepared.

[0089] (6) Take 300mL of anhydrous ethanol and heat it at 50℃, and then add 30g of polyvinyl butyral to it, and stir for 40min to obtain a polyvinyl butyral solution. Then, add 3g of modified lignin nanoparticles to it, and continue to heat and stir for 30min to prepare a water-resistant solution.

[0090] (7) Take 30 g of oil-resistant solution and 70 g of water-resistant solution to compound, stir for 30 min on a magnetic stirrer, then perform ultrasonic treatment for 20 min under a power of 200 W to prepare a uniformly mixed water-resistant and oil-resistant composite solution, then uniformly coat the composite solution on the surface of the base paper prepared in step (1) on a roll coater, the coating speed is 5 cm / s, and the coating amount is 8 g / m 2 Finally, place the paper in a vacuum drying oven, the drying temperature is 50 ℃, and the drying time is 30 min to prepare the biomass-based water-resistant and oil-resistant packaging paper.

[0091] Comparative Example 1

[0092] The preparation method of Reference Example 1 is referred to, but the operation of pretreating the base paper with a calcium chloride solution in Example 1 is omitted, that is, the water-resistant and oil-resistant solutions are directly coated on the surface of the base paper, and the other operations remain the same as in Example 1 to prepare the biomass-based water-resistant and oil-resistant packaging paper.

[0093] Comparative Example 2

[0094] The preparation method of Reference Example 1 is referred to, but the operation of preparing the modified sulfonated nanocellulose solution in Example 1 is omitted, that is, the oil-resistant layer is only composed of ethyl cellulose solution, and the other operations remain the same as in Example 1 to prepare the biomass-based water-resistant and oil-resistant packaging paper.

[0095] Comparative Example 3

[0096] The preparation method of Reference Example 1 is referred to, but the operation of preparing the ethyl cellulose solution in Example 1 is omitted, that is, the oil-resistant layer is only composed of modified sulfonated nanocellulose solution, and the other operations remain the same as in Example 1 to prepare the biomass-based water-resistant and oil-resistant packaging paper.

[0097] Comparative Example 4

[0098] The preparation method of Reference Example 1 is referred to, but the operation of preparing the modified lignin nanoparticle solution in Example 1 is omitted, that is, the water-resistant layer is only composed of polyvinyl butylal solution, and the other operations remain the same as in Example 1 to prepare the biomass-based water-resistant and oil-resistant packaging paper.

[0099] Comparative Example 5

[0100] The preparation method of Reference Example 1 is referred to, but the operation of preparing the polyvinyl butylal solution in Example 1 is omitted, that is, the water-resistant layer is only composed of modified lignin nanoparticle solution, and the other operations remain the same as in Example 1 to prepare the biomass-based water-resistant and oil-resistant packaging paper.

[0101] Comparative Example 6

[0102] The preparation method of Reference Example 1 is referred to, but the difference is that conifer pulp is used instead of Enteromorpha nanocellulose, specifically, step (2) is modified as:

[0103] (2) Add 20 g of bleached coniferous wood pulp into TEMPO / NaClO / NaBr system (0.05 g TEMPO, 0.5 g NaBr and 50 mL NaClO solution in 500 mL deionized water), adjust the pH value of the reaction system to 10 with 0.1 mol / L HCl and NaOH, then homogenize 15 times under 180 MPa, and obtain the nanocellulose of coniferous wood pulp after filtration.

[0104] The fiber length and properties of the prepared nanocellulose of coniferous wood pulp are similar to those of the nanocellulose of Sargassum thunbergii prepared in step (2), and modified cellulose can also be prepared. Other operations and example 1 remain unchanged, and a biomass-based water-resistant and oil-resistant packaging paper is prepared.

[0105] Comparative Example 7

[0106] The preparation method of reference example 1 is referred to, but an equal amount of methyl cellulose is used to replace the ethyl cellulose in example 1, that is, the oil-resistant layer is composed of Sargassum thunbergii modified sulfonated nanocellulose and methyl cellulose solution, and other operations and example 1 remain unchanged. A biomass-based water-resistant and oil-resistant packaging paper is prepared.

[0107] Comparative Example 8

[0108] The preparation method of reference example 1 is referred to, but an equal amount of carnauba wax is used to replace the polyvinyl butyral in example 1, that is, the water-resistant layer is composed of modified lignin nanoparticles and carnauba wax solution, and other operations and example 1 remain unchanged. A biomass-based water-resistant and oil-resistant packaging paper is prepared.

[0109] Comparative Example 9

[0110] The preparation method of reference example 1 is referred to, but an equal amount of modified lignin is used to replace the modified lignin nanoparticles prepared in example 1, that is, the water-resistant layer is composed of modified lignin and polyvinyl butyral solution, and other operations and example 1 remain unchanged. A biomass-based water-resistant and oil-resistant packaging paper is prepared.

[0111] Performance test of product of example 5

[0112] The water-resistant and oil-resistant packaging paper prepared by the examples and comparative examples is tested for performance, and the test method is as follows:

[0113] (1) Oil resistance test:

[0114] The method of standard TAPPI T 559-“Grease resistance test for paper and paperboard” is referred to.

[0115] (2) Water resistance test:

[0116] GB / T1540-2002 "Determination of water absorption of paper and paperboard - Cobb method".

[0117] (3) Tensile strength test:

[0118] GB / T12914-2018 "Paper and paperboard - Determination of tensile strength - Constant rate of tension method".

[0119] (4) Air permeability test:

[0120] GB / T458-2008 “Paper and board—Determination of air permeability”.

[0121] (5) Water vapor transmission rate test:

[0122] GB / T22921-2008 “Paper and paperboard thin materials - Determination of water vapour transmission rate - Dynamic airflow method and static gas method”.

[0123] (6) Degradation performance test:

[0124] GB / T39951-2021 "Evaluation method for the degradation performance of disposable paper products".

[0125] The test results are as follows:

[0126] The experimental results are as follows Figs. 1-7 As shown, it can be seen that:

[0127] The difference between Comparative Example 1 and Example 1 is that the base paper is not pretreated with calcium chloride solution; 2+ exists, but cannot react with -COOH in modified sulfonated nanocellulose. - Combined with the above, the tensile strength of water-resistant and oil-resistant paper shows a downward trend.

[0128] The difference between Comparative Example 2 and Example 1 is that the oil-resistant layer is composed only of ethyl cellulose solution; since the oil-resistant layer does not contain modified sulfonated nanocellulose solution, the pores on the surface of the base paper are not fully filled, resulting in a downward trend in the oil-proof performance and tensile strength of the water-resistant and oil-resistant paper, and an upward trend in the water vapor permeability and air permeability, thereby reducing the overall performance of the water-resistant and oil-resistant paper.

[0129] The difference between Comparative Example 3 and Example 1 is that the oil-resistant layer is composed only of a modified sulfonated nanocellulose solution; since the oil-resistant layer does not contain an ethyl cellulose solution, the pores on the surface of the base paper are not fully filled, resulting in a downward trend in the oil-proof performance and tensile strength of the water-resistant and oil-resistant paper, and an upward trend in the water vapor permeability and air permeability, thereby reducing the overall performance of the water-resistant and oil-resistant paper.

[0130] The difference between Comparative Example 4 and Example 1 is that the water-resistant layer is composed only of polyvinyl butyral solution; since the water-resistant layer does not contain modified lignin nanoparticle solution, the pores on the surface of the base paper are not fully filled, resulting in a downward trend in the water resistance and tensile strength of the water-resistant and oil-resistant paper, and an upward trend in the water vapor permeability and air permeability, thereby reducing the overall performance of the water-resistant and oil-resistant paper.

[0131] The difference between Comparative Example 5 and Example 1 is that the water-resistant layer is composed only of a modified lignin nanoparticle solution; since the water-resistant layer does not contain a polyvinyl butyral solution, the pores on the surface of the base paper are not fully filled, resulting in a downward trend in the water resistance and tensile strength of the water-resistant and oil-resistant paper, and an upward trend in the water vapor permeability and air permeability, thereby reducing the overall performance of the water-resistant and oil-resistant paper.

[0132] The difference between Comparative Example 6 and Example 1 is that the oil-resistant layer is composed of coniferous wood modified sulfonated nanocellulose and ethyl cellulose solution; since the oil-resistant layer does not contain sulfonated nanocellulose solution modified by Sargassum fusiformis, the oil-proof performance and tensile strength of the water-resistant and oil-resistant paper show a downward trend, while the water vapor permeability and air permeability show an upward trend, and the overall performance of the water-resistant and oil-resistant paper is reduced.

[0133] The difference between Comparative Example 7 and Example 1 is that the oil-resistant layer is composed of sulfonated nanocellulose modified with Sargassum fusiformis and a methylcellulose solution; since equal mass of methylcellulose increases the viscosity of the solution, coating is difficult, and the film-forming property of methylcellulose is poor, resulting in a downward trend in the oil-proof performance, water-proof performance, and tensile strength of the water-resistant and oil-resistant paper, and an upward trend in the water vapor permeability and air permeability, and the overall performance of the water-resistant and oil-resistant paper is reduced.

[0134] The difference between Comparative Example 8 and Example 1 is that the water-resistant layer is composed of modified lignin nanoparticles and carnauba wax solution; since the water-resistant layer does not contain polyvinyl butyral solution, the film-forming property of the base paper surface deteriorates and the pores are not fully filled, resulting in a downward trend in the water resistance and tensile strength of the water-resistant and oil-resistant paper, an upward trend in the water vapor permeability and air permeability, and a reduction in the overall performance of the water-resistant and oil-resistant paper.

[0135] The difference between Comparative Example 9 and Example 1 is that the water-resistant layer is composed of modified lignin and polyvinyl butyral solution; since the water-resistant layer does not contain modified lignin nanoparticle solution, the tiny pores on the surface of the base paper are not fully filled, resulting in the water resistance and tensile strength of the water-resistant and oil-resistant paper showing a downward trend, and the water vapor permeability and air permeability showing an upward trend, thereby reducing the overall performance of the water-resistant and oil-resistant paper.

[0136] To sum up, the biomass-based water-resistant and oil-resistant packaging paper prepared in the embodiment of the present invention adopts a composite water-resistant / oil-resistant layer, the coating is more tightly combined with the paper, and has a high oil resistance grade, high tensile strength, low water vapor permeability, low air permeability, good water resistance and degradation performance.

[0137] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for preparing biomass-based water-resistant and oil-resistant packaging paper, characterized in that The following steps are involved: (1) Using a calcium chloride solution with a concentration of 1-3% to impregnate the base paper for 4-10 minutes, and then drying to obtain the pretreated base paper; (2) Preparation of nanocellulose using Sargassum fusiformis; (3) Sodium dodecyl sulfate was added to anhydrous ethanol, and the mixture was stirred and heated at 50-70°C for 30-50 minutes. The nanocellulose obtained in step (2) was then added and the mixture was stirred and heated for reaction, washed, and ultrasonicated to obtain modified sulfonated nanocellulose. (4) Add ethyl cellulose to anhydrous ethanol, stir and heat at 30-50°C for 20-40 minutes, then add the modified sulfonated nanocellulose obtained in step (3) and continue stirring and heating for 20-40 minutes to obtain an oil-resistant solution; (5) Add alkali lignin to anhydrous ethanol, stir and heat at 40-60°C for 40-80 min, then add water and continue stirring and heating for 20-40 min, collect the supernatant, centrifuge at 4000-6000 rpm for 10-30 min, and remove ethanol by rotary evaporation to obtain lignin nanoparticles; (6) Adding the lignin nanoparticles prepared in step (5), octadecylamine, and ferulic acid to anhydrous ethanol, stirring and heating at 50-70° C. for 3-5 h, cooling, filtering, and drying to obtain modified lignin nanoparticles; (7) Add polyvinyl butyral to anhydrous ethanol, stir and heat at 40-60°C for 30-50 minutes, then add the modified lignin nanoparticles obtained in step (6), continue stirring and heating for 20-40 minutes to obtain an aqueous solution-resistant solution; (8) stirring and mixing the oil-resistant solution obtained in step (4) and the water-resistant aqueous solution obtained in step (7) for 20 to 40 minutes, and ultrasonicating to obtain a water-resistant and oil-resistant composite solution; (9) coating the water-resistant and oil-resistant composite solution obtained in step (8) on the pretreated base paper obtained in step (1), and drying the solution to obtain a biomass-based water-resistant and oil-resistant packaging paper; The preparation method of the nanocellulose described in step (2) is: The dried product of Sargassum fusiformis was soaked in water for expansion, and the soaked Sargassum fusiformis was placed in a 20wt% Na2CO3 solution and evenly mixed for 1 hour, then dried, washed, and placed in a 3wt% acetic acid solution for reaction for 2 hours. Then, a 30wt% H2O2 solution was added for reaction for 2 hours, washed, added with deionized water, and then homogenized 20 times at 200MPa and filtered to obtain Sargassum fusiformis nanocellulose.

2. The preparation method according to claim 1, wherein: The base paper in step (1) is a paper made from raw wood pulp and having a rough surface; The drying condition in step (1) is drying at 30-50° C. for 5-20 minutes.

3. The preparation method according to claim 1, wherein: The mass ratio of sodium lauryl sulfonate to nanocellulose in step (3) is 1-2:1-2; The ratio of anhydrous ethanol, ethyl cellulose and modified sulfonated nanocellulose in step (4) is 100 mL: 4-10 g: 2-6 g.

4. The preparation method according to claim 3, wherein: The mass ratio of sodium lauryl sulfonate to nanocellulose in step (3) is 2:1; The ratio of anhydrous ethanol, ethyl cellulose and modified sulfonated nanocellulose in step (4) is 100 mL: 7 g: 3 g.

5. The preparation method according to claim 1, wherein: The mass ratio of the lignin nanoparticles, octadecylamine and ferulic acid in step (6) is 2-3:1-2:1-2; The ratio of anhydrous ethanol, polyvinyl butyral and modified lignin nanoparticles in step (7) is 100 mL: 5-20 g: 1-2 g.

6. The preparation method according to claim 5, characterized in that: The mass ratio of the lignin nanoparticles, octadecylamine and ferulic acid in step (6) is 5:3:2; The ratio of anhydrous ethanol, polyvinyl butyral and modified lignin nanoparticles in step (7) is 100 mL: 10 g: 1 g.

7. The preparation method according to claim 1, wherein: The mass ratio of the oil-resistant solution to the water-resistant solution in step (8) is 1-3:1-3.

8. The preparation method according to claim 1, wherein: The coating in step (9) is performed using a roller coater; The coating conditions in step (9) are as follows: a coating rate of 4 to 6 cm / s and a coating amount of 6 to 10 g / m 2 ; The drying condition in step (9) is drying at 40-60° C. for 20-40 minutes.

9. A biomass-based water-resistant and oil-resistant packaging paper, prepared according to the preparation method according to any one of claims 1 to 8.

Images