Biomass-based water-resistant oil-resistant biodegradable coated paper as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of food packaging paper, and particularly discloses biomass-based water-resistant and oil-resistant biodegradable coated paper and a preparation method and application thereof.The biomass-based water-resistant and oil-resistant biodegradable coated paper is prepared by taking food-grade packaging base paper as a substrate, uniformly mixing sodium carboxymethyl cellulose, water and a plasticizer to form coating liquid, coating the surface of the base paper for food packaging with the coating liquid, and drying the coating liquid to obtain the biomass-based water-resistant and oil-resistant biodegradable coated paper. And dipping the base paper coated with the coating liquid into a ferric chloride solution, taking out and drying to obtain the biomass-based water-resistant and oil-resistant biodegradable coated paper. The preparation method is simple, the reaction condition is mild, the novel method for rapidly preparing the water-resistant and oil-resistant packaging paper in an environment-friendly and large-scale mode is achieved, and the prepared paper has good water-resistant and oil-resistant performance and is expected to be widely applied to the field of food packaging.

Description

Technical Field

[0001] The invention relates to the technical field of food packaging paper, in particular to a biomass-based water- and oil-blocking biodegradable coated paper and a preparation method and application thereof. Background Art

[0002] With the development of take-out, express delivery, e-commerce and other industries, the use of disposable take-out food packaging tableware, especially traditional plastic packaging bags and polystyrene plastic lunch boxes, has increased significantly, causing white pollution problems. With the introduction of plastic restriction policies around the world, fully biodegradable packaging materials have attracted widespread attention. Among them, paper-based packaging materials are widely used in the field of food packaging because of their advantages such as renewable, recyclable and biodegradable. However, the problems of paper-based materials being easy to penetrate oil and easy to break when immersed in water have limited their application in the field of food packaging to a certain extent. The traditional way to modify paper to be hydrophobic and oleophobic is to add fluorinated oil-proof additives during the papermaking process to reduce the surface tension of the paper-based material, thereby achieving the purpose of waterproofing and oil-proofing. As the material or product comes into contact with food, the residual perfluoroalkyl or polyfluoroalkyl compounds may migrate to the food, and then may be ingested by the human body, continue to act in the human body, and have a potential risk of carcinogenesis. Disposable paper bags, paper boxes, pulp molding and other products used for food packaging need to have good oil and water resistance. Fluorine-free oil repellents prevent the penetration of oil molecules by forming a dense and uniform barrier layer on the surface of paper-based materials (water-based acrylic resins, silicone resins (water- and oil-blocking, non-biodegradable), starch and other biomass film layers (only oil-blocking but not water-blocking)).

[0003] Therefore, seeking a biodegradable functional coating material with both waterproof and oil-proof properties remains an important technical problem that needs to be solved. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a biomass-based water- and oil-resistant biodegradable coated paper and a preparation method and application thereof.

[0005] To achieve the above object, the present invention is implemented according to the following technical solutions:

[0006] One of the technical solutions of the present invention is to provide a method for preparing a biomass-based water- and oil-blocking biodegradable coated paper, comprising the following steps:

[0007] S1, dissolving sodium carboxymethyl cellulose in deionized water to form a sodium carboxymethyl cellulose aqueous solution with a mass concentration of 1.5% to 2.5%, taking a plasticizer according to a mass ratio of sodium carboxymethyl cellulose to plasticizer of 1:(0.15 to 0.3), dissolving it in the sodium carboxymethyl cellulose aqueous solution to obtain a coating liquid;

[0008] S2, applying the coating liquid to the surface of the base paper for food packaging, and obtaining the food packaging paper containing the waterproof and oil-proof coating after drying;

[0009] S3. Soak the food packaging paper containing the waterproof and oil-proof coating in an aqueous solution of ferric chloride for 5-30 minutes, take it out and dry it to obtain a biomass-based water-proof and oil-proof biodegradable coated paper.

[0010] Furthermore, in step S1, the plasticizer is one or more of glycerol, sorbitol, mannitol and maltitol.

[0011] Furthermore, in the step S2, the coating amount of the coating liquid on the surface of the food packaging base paper is 10 to 30 g / m 2 .

[0012] Furthermore, in said step S3, the concentration of the aqueous ferric chloride solution is 0.01 mol / L-0.1 mol / L.

[0013] Preferably, in steps S2 and S3, the drying temperature is 40°C to 70°C.

[0014] A second technical solution of the present invention is to provide a biomass-based water- and oil-resistant biodegradable coated paper prepared by the method according to any one of claims 1 to 5.

[0015] The third technical solution of the present invention is to provide a biomass-based water- and oil-resistant biodegradable coated paper for use in food packaging.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] (1) The present invention uses sodium carboxymethyl cellulose as a film-forming aid to perform surface immersion coating on food contact packaging paper. 3+ After cross-linking and drying, the sodium carboxymethyl cellulose can be given a higher degree of cross-linking and better water- and oil-blocking properties, so that a biomass-based water- and oil-blocking biodegradable coated paper with good water- and oil-blocking properties can be prepared.

[0018] (2) The biomass-based water- and oil-resistant biodegradable coated paper prepared by the present invention has very good water- and oil-resistant properties, can withstand vegetable oil stains on the back for more than 24 hours, and can withstand water immersion for more than 1 hour.

[0019] (3) The biomass-based water- and oil-resistant biodegradable coated paper prepared by the present invention has a simple preparation process and mild reaction conditions, and can be used for large-scale preparation and industrial application of disposable food contact tableware such as disposable paper cups, paper straws, and paper tableware. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1This is a scanning electron microscope image (SEM) of the surface of the base paper for food packaging that is not coated with the coating liquid of Example 1;

[0021] Figure 2 This is a scanning electron microscope image (SEM) of a cross section of a base paper for food packaging that is not coated with the coating liquid of Example 1;

[0022] Figure 3 The scanning electron microscope (SEM) image of the surface of the base paper for food packaging coated with the coating liquid of Example 1;

[0023] Figure 4 The scanning electron microscope image (SEM) of the cross section of the base paper for food packaging coated with the coating liquid of Example 1;

[0024] Figure 5 This is a scanning electron microscope image (SEM) of the surface of the biomass-based water- and oil-blocking biodegradable coated paper prepared in Example 1;

[0025] Figure 6 This is a scanning electron microscope image (SEM) of a cross section of the biomass-based water- and oil-blocking biodegradable coated paper prepared in Example 1;

[0026] Figure 7 This is an optical picture of the oil barrier effect of uncross-linked paper with different coating amounts tested by the Kit method;

[0027] Figure 8 The optical pictures are of the water-blocking effect of the base paper for food packaging which is not coated with the coating liquid of Example 1 and the base paper which is coated with the coating liquid of Example 1;

[0028] Fig. 9 These are optical pictures of the oil-blocking effect of a base paper for food packaging that is not coated with the coating liquid of Example 1 and a base paper coated with the coating liquid of Example 1 for 48 hours. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments. The specific embodiments described herein are only used to explain the present invention and are not used to limit the invention.

[0030] Example 1

[0031] 1) Dissolve 25 g of sodium carboxymethyl cellulose (viscosity 600-3000 mPa.s) and 7.5 g of sorbitol in 75 g of deionized water to obtain a coating solution.

[0032] 2) Dissolve ferric chloride hexahydrate in 500 g of deionized water to prepare a 0.1 mol / L ferric chloride aqueous solution.

[0033] 3) Apply the prepared coating liquid to the surface of the food packaging base paper (coating amount 30g / m 2 ), dried at 40℃.

[0034] 4) After the base paper coated with the coating liquid is immersed in a ferric chloride solution for 5 minutes, it is taken out and dried at 40° C. to obtain a biomass-based water- and oil-resistant biodegradable coated paper.

[0035] Figure 1 , Figure 2 The SEM images of the surface and cross section of the base paper for food packaging without coating liquid are shown in Figure 1. Figure 3 , Figure 4 The SEM images of the surface and cross section of the base paper for food packaging coated with the coating liquid are shown in Figure 1. Figure 5 , Figure 6 These are the SEM images of the surface and cross section of the paper after cross-linking treatment in an aqueous solution of ferric chloride. It can be seen from the figure that the cellulose on the surface of the base paper without any treatment is distributed crosswise and vertically, with pore structures of varying sizes. After the surface coating of sodium carboxymethyl cellulose, the surface of the paper is smooth and flat, without a pore structure; the cross-sectional view shows that a layer of carboxymethyl cellulose film is evenly coated on the surface of the paper, which reduces the penetration of oil droplets into the interior of the paper to a certain extent. The skeleton structure of the fiber appears on the surface of the paper after cross-linking treatment, and it can be seen from the cross-sectional view that the thickness of the carboxymethyl cellulose film layer is reduced compared to before cross-linking. This may be because after the high-valent ion cross-linking treatment, the three-dimensional network structure between the carboxymethyl cellulose is more compact, further improving the barrier ability of the film layer to water and oil.

[0036] Specifically, the Kit method commonly used for oil-proof paper was used to determine the oil-proof grade of the modified paper. The test showed that the oil-proof grade of the modified paper could reach KIT-6 or above even without being soaked and cross-linked in ferric chloride solution. When the coating amount reached 20g / m 2 When the coating amount reaches 30g / m 2 When the oil resistance level can reach KIT-11 or above ( Figure 7 ). Considering some practical situations in the application of modified paper tableware, from meal packaging to take-out delivery, and then to the hands of customers, the whole process lasts relatively long. Only the traditional Kit method for detecting the oil resistance level and the 15s oil resistance test cannot meet the requirements of practical application. Therefore, in this embodiment, in combination with practical applications, a drop of vegetable oil (including 80°C hot oil) is dripped onto the surface of the modified paper at a height of 15mm with a rubber-tipped dropper, and the time it takes for the oil drop to penetrate the surface of the modified paper is observed and recorded every 5 minutes to truly reflect its application performance; similarly, a drop of water is dripped with a rubber-tipped dropper, and it is observed every 5 minutes, and the time it takes for the water drop to penetrate the paper is recorded; the test results are as follows Figure 8 and Fig. 9 As shown by Figure 8 and Fig. 9 It can be seen that the biomass-based water- and oil-resistant biodegradable coated paper prepared in this embodiment can withstand water penetration for 90 minutes and oil penetration for more than 48 hours.

[0037] Example 2

[0038] 1) Dissolve 15 g of sodium carboxymethyl cellulose (viscosity 3000-5000 mPa.s) and 2.25 g of glycerol in 85 g of deionized water to obtain a coating solution.

[0039] 2) Dissolve ferric chloride hexahydrate in 500 g of deionized water to prepare a 0.01 mol / L ferric chloride aqueous solution.

[0040] 3) Apply the prepared coating liquid to the surface of the base paper for food packaging (coating amount 10g / m 2 ), dried at 70°C.

[0041] 4) After the base paper coated with the coating liquid is immersed in a ferric chloride solution for 30 minutes, it is taken out and dried at 70° C. to obtain a biomass-based water- and oil-resistant biodegradable coated paper.

[0042] The same test method as in Example 1 was used to test that the biomass-based water- and oil-resistant biodegradable coated paper prepared in this example could withstand water penetration for 35 minutes and oil penetration for more than 24 hours.

[0043] Example 3

[0044] 1) Dissolve 20 g of sodium carboxymethyl cellulose (viscosity 1500-3000 mPa.s) and 4 g of mannitol in 80 g of deionized water to obtain a coating solution.

[0045] 2) Dissolve ferric chloride hexahydrate in 500 g of deionized water to prepare a 0.05 mol / L ferric chloride aqueous solution.

[0046] 3) Apply the prepared coating liquid to the surface of the food packaging base paper (coating amount 15g / m 2 ), and dried at 60°C to obtain a biomass-based water- and oil-resistant biodegradable coated paper.

[0047] 4) Soak the base paper coated with the coating liquid in the ferric chloride solution for 15 minutes, then take it out and dry it at 60°C.

[0048] The same test method as in Example 1 was used to test that the biomass-based water- and oil-resistant biodegradable coated paper prepared in this example could withstand water penetration for 45 minutes and oil penetration for more than 30 hours.

[0049] Example 4

[0050] 1) Dissolve 25 g of sodium carboxymethyl cellulose (viscosity 600-1000 mPa.s) and 3.75 g of maltitol in 75 g of deionized water to obtain a coating solution.

[0051] 2) Dissolve ferric chloride hexahydrate in 500 g of deionized water to prepare a 0.10 mol / L ferric chloride aqueous solution.

[0052] 3) Apply the prepared coating liquid to the surface of the food packaging base paper (coating amount 25g / m 2 ), dried at 50°C.

[0053] 4) After the base paper coated with the coating liquid is immersed in a ferric chloride solution for 10 minutes, it is taken out and dried at 50° C. to obtain a biomass-based water- and oil-resistant biodegradable coated paper.

[0054] The same test method as in Example 1 was used to test that the biomass-based water- and oil-resistant biodegradable coated paper prepared in this example could withstand water penetration for 75 minutes and oil penetration for more than 48 hours.

[0055] In summary, the coated paper of the present invention has good water and oil barrier properties and can be used for food packaging.

[0056] The technical solution of the present invention is not limited to the above-mentioned specific embodiments. All technical variations made according to the technical solution of the present invention fall within the protection scope of the present invention.

Claims

1. A method for preparing biomass-based water- and oil-blocking biodegradable coated paper, characterized in that: The following steps are involved: S1, dissolving sodium carboxymethyl cellulose in deionized water to form a sodium carboxymethyl cellulose aqueous solution with a mass concentration of 1.5% to 2.5%, taking a plasticizer according to a mass ratio of sodium carboxymethyl cellulose to plasticizer of 1:(0.15 to 0.3), dissolving it in the sodium carboxymethyl cellulose aqueous solution to obtain a coating liquid; S2, applying the coating liquid to the surface of the base paper for food packaging, and obtaining the food packaging paper containing the waterproof and oil-proof coating after drying; S3. Soak the food packaging paper containing the waterproof and oil-proof coating in an aqueous solution of ferric chloride for 5-30 minutes, take it out and dry it to obtain a biomass-based water-proof and oil-proof biodegradable coated paper.

2. The method for preparing the biomass-based water- and oil-blocking biodegradable coated paper according to claim 1, characterized in that: In the step S1, the plasticizer is one or more of glycerol, sorbitol, mannitol and maltitol.

3. The method for preparing the biomass-based water- and oil-blocking biodegradable coated paper according to claim 1, characterized in that: In the step S2, the coating amount of the coating liquid on the surface of the food packaging base paper is 10 to 30 g / m 2 .

4. The method for preparing the biomass-based water- and oil-blocking biodegradable coated paper according to claim 1, characterized in that: In the step S3, the concentration of the ferric chloride aqueous solution is 0.01 mol / L-0.1 mol / L.

5. The method for preparing the biomass-based water- and oil-blocking biodegradable coated paper according to claim 1, characterized in that: In the steps S2 and S3, the drying temperature is 40°C to 70°C.

6. A biomass-based water- and oil-resistant biodegradable coated paper prepared by the method according to any one of claims 1 to 5.

7. Use of the biomass-based water- and oil-resistant biodegradable coated paper as claimed in claim 6 in food packaging.

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