Fluorine-free plastic-free recyclable degradable food packaging barrier material

Abstract

The fluoride-free plastic-free recyclable degradable food packaging barrier material provided by the invention has barrier properties of food packaging materials in the fast moving consumer goods industry, and solves the problems that coated paper and waxed paper in an existing food packaging material are difficult to recycle or cannot be recycled and cannot be composted and degraded. Therefore, the negative influence of the oil-proof paper on the environment is reduced. The novel bio-based fluoride-free plastic-free recyclable compostable degradable food packaging barrier material provided by the invention has the barrier property of food packaging materials in the fast moving consumer goods industry; meanwhile, the problems that coated paper and waxed paper in an existing food packaging material are difficult to recover or cannot be recovered and cannot be composted and degraded, and oil-proof paper has negative effects on the environment and a human body are solved, so that the defects in the prior art are overcome.

Description

Technical Field

[0001] The invention belongs to the technical field of food packaging materials, and specifically relates to a fluorine-free, plastic-free, recyclable and degradable food packaging barrier material. Background Art

[0002] At present, the food packaging materials in the fast-moving consumer goods industry on the market mainly include plastic coated paper, oil-proof paper and waxed paper. Among them, plastic coated paper mainly uses the extrusion casting process to process plastic particles (polyethylene PE, polypropylene PP, etc.) onto the base paper. It has good waterproof and oil-proof properties, but it is not recyclable or difficult to recycle (it is necessary to separate the paper and plastic first and then recycle the plastic part and the paper part separately, which is energy-intensive and polluting). Moreover, after the material overflows the recycling system and enters the natural environment, the plastic part will not be compostable and degradable for a long time like ordinary plastic, causing pollution and damage to the natural environment and other organisms.

[0003] Moreover, oil-proof paper is produced by adding oil-proof agents to the pulp or coating the surface. It can resist oil penetration and absorption and has good oil-proof properties, but no water-proof properties. In addition, the oil-proof agents used in it contain perfluorinated and polyfluoroalkyl substances such as PFAS, which are not easy to decompose and have been proven to accumulate in the environment and people's bodies. Exposure to certain types of PFAS may have serious health effects. Waxed paper is made by melting wax and then coating it on the surface. It has good oil and moisture-proof properties, but the wax coating has low temperature resistance and is easy to peel off the paper at high temperatures. It is also difficult to recycle and the product cannot be composted and degraded. Summary of the invention

[0004] The purpose of the present invention is to provide a fluorine-free, plastic-free, recyclable and degradable food packaging barrier material. The provided material not only has the barrier properties of food packaging materials in the fast-moving consumer goods industry, but also solves the problems of coated paper and waxed paper in existing food packaging materials being difficult or impossible to recycle and non-compostable, thereby reducing the negative impact of oil-proof paper on the environment and making up for the shortcomings of the prior art.

[0005] The present invention provides a fluorine-free, plastic-free, recyclable and degradable food packaging barrier material, comprising a first base paper substrate layer, a second basic barrier layer and a third functional layer; wherein the second basic barrier layer is coated with grafted starch;

[0006] The preparation method of the grafted starch is as follows: water and corn starch are stirred evenly and then heated to 45±2°C, ammonium persulfate initiator is added for stirring reaction, and then butyl acrylate is added dropwise, and the reaction is carried out at a constant temperature of 30°C for 2 to 4 hours, and a hydroquinone solution is added to terminate the reaction, and the reaction product is washed with water, and the washed starch is dried to obtain the grafted starch.

[0007] As a preferred embodiment, the first base paper layer is preferably food contact paper with a grammage of 18 to 100 g / ㎡;

[0008] As a preferred embodiment, the second base barrier layer coating has a gram weight of 0.1 to 5 g / ㎡;

[0009] As a preferred embodiment, the third functional layer is selected from inorganic coating, biodegradable coating, water-based acrylic coating or water-based silicone coating;

[0010] Furthermore, the coating weight of the third functional layer is 0.1 to 5 g / ㎡.

[0011] The food packaging barrier material provided by the present invention has a preparation method as follows:

[0012] 1) Preparation of the second base barrier layer

[0013] Pour water into the starch gelatinization kettle, start stirring, weigh the grafted starch and add it to the starch gelatinization kettle, stir evenly, and then start heating to 95-98°C, and keep it at this temperature for 30 minutes, then cool it down to about 60-65°C to form starch gelatinization liquid for use.

[0014] 2) Preparation of the second base barrier layer

[0015] The starch gelatinized liquid is evenly coated on the paper through the sizing system at a machine speed of 50-300m / min and a drying temperature of 80-180℃ to form the second basic barrier layer, and then rolled up after drying;

[0016] 3) Functional coating

[0017] The functional coating is placed in the coating machine trough, and the coating operation is carried out at a speed of 20m / min-180m / min. The functional coating is transferred to the paper with the basic barrier layer, and the paper is dried and rolled at 50-180℃ to prepare the food packaging barrier material.

[0018] The present invention also provides application of the provided food packaging barrier material in preparing food packaging products.

[0019] The present invention provides a novel bio-based fluorine-free, plastic-free, recyclable and compostable food packaging barrier material, which has the barrier properties of food packaging materials in the fast-moving consumer goods industry and solves the problems of coated paper and waxed paper in existing food packaging materials being difficult or impossible to recycle and non-compostable, as well as the negative impact of oil-proof paper on the environment and human body, thereby making up for the deficiencies of the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1: Schematic diagram of the layered structure of the novel bio-based fluorine-free, plastic-free, recyclable, compostable and degradable food packaging barrier material of the present invention;

[0021] Figure 2 : Barrier effect diagram of the novel bio-based fluorine-free, plastic-free, recyclable, compostable and degradable food packaging barrier material of the present invention;

[0022] Figure 3 : Schematic diagram of the recycling and repulping effect of the new bio-based fluorine-free, plastic-free, recyclable, compostable and degradable food packaging barrier material of the present invention. DETAILED DESCRIPTION

[0023] The food packaging barrier material protected by the present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0024] Example 1: Screening of modified starch

[0025] The food packaging barrier material provided by the present invention comprises a first base paper substrate layer, a second basic barrier layer and a third functional layer, wherein the base paper substrate of the first base paper layer can be conventional food packaging paper, preferably 18-100g / ㎡ food contact paper; the second basic barrier layer is formed by uniformly coating the modified starch gelatinized liquid on the paper through a sizing system at a machine speed of 50-300m / min and a drying temperature of 80-180°C, and then drying and rolling. The third functional layer is coated on the basic barrier layer, and the third functional layer can be an inorganic coating, a biodegradable coating, a water-based acrylic coating or a water-based silicone coating.

[0026] The food packaging barrier material is prepared according to the following method, comprising the following steps:

[0027] 1) Preparation of modified starch gelatinized liquid

[0028] Pour 1800kg of water into the starch gelatinization kettle, start stirring, weigh 200kg of modified starch and add it to the kettle. After stirring evenly, start heating to 95-98℃ and keep it at this temperature for 30 minutes. Then cool it to about 60-65℃ to form starch gelatinization liquid for use. Stirring is continuous throughout the whole process.

[0029] 2) Coating to prepare the second base barrier layer

[0030] The starch gelatinized liquid is passed through the sizing system and evenly coated on the paper at a machine speed of 50-300m / min and a drying temperature of 80-180℃ to form the second basic barrier layer, which is then rolled up after drying. The coating weight of the second basic barrier layer is 0.1-5g / ㎡.

[0031] 3) Applying functional coating

[0032] Put the functional coating into the coating machine trough, and carry out coating operation at a speed of 20m / min-180m / min, transfer the functional coating to the paper with the basic barrier layer, dry it at 50-180℃ to form the third functional layer, and roll it up to prepare the food packaging barrier material. The coating weight of the third functional layer is 0.1-5g / ㎡.

[0033] In order to obtain the best effect, the types of modified starch were screened.

[0034] 1. Oxidized starch

[0035] Cassava starch (but other types of starch) is ground into small particles and washed with hydrochloric acid to remove impurities and the outer layer of the particles. The starch is then separated from other impurities by wet or dry extraction. The treated starch slurry is then subjected to an oxidation-reduction reaction with an oxidant such as hydrogen peroxide or nitrogen peroxide to oxidize some of the active groups such as hydroxyl groups and aldehyde groups in the starch molecules into groups such as aldehyde groups and carboxyl groups. After the oxidation-reduction reaction is completed, the reaction product is fully washed multiple times to remove residual impurities such as oxidants, acids, and salts. The washed starch is dried by spray drying or oven drying to reduce its moisture content to below the target value, thereby obtaining oxidized starch.

[0036] 2. Grafted starch

[0037] The preparation method of grafted starch is as follows: add 1kg of water to the reactor, start stirring, pour in 1.5kg of corn starch, stir evenly and heat to 45±2°C, add 10g of ammonium persulfate initiator, but other organic and inorganic substances that form a redox system can also be used as initiators. After stirring for 30 minutes, slowly add 0.5kg of butyl acrylate, keep the temperature at 30°C for 2 to 4 hours, add hydroquinone with a final concentration of 5% (mass fraction) to terminate the reaction, and wash the reaction product with water several times to remove residual impurities. The washed starch is spray-dried to obtain grafted starch.

[0038] 3. Enzymatic modification

[0039] Remove impurities from the original cassava starch to ensure the purity of the starch, wash it with water and suspend it in an appropriate amount of water for soaking. Add glucose amylase to hydrolyze the α-1,4-glycosidic bonds in the starch molecules to hydrolyze the starch into glucose molecules, adjust the pH value to 4.5-6.0, maintain the temperature at 50-60℃, and hydrolyze for 12 hours. After the enzymolysis is completed, inactivate the enzymolysis solution at 100℃ for 10 minutes.

[0040] 4. Filter the reaction solution to remove unreacted starch particles, enzymes and other impurities. The filtered product needs to be fully washed to remove residual enzymes and other soluble substances. The washed product is dried to remove moisture and prepared into enzymatically modified starch.

[0041] According to the preparation method of food packaging barrier materials determined above, food packaging barrier materials (material 1) were made using oxidized starch, food packaging barrier materials (material 2) were made using grafted starch, and food packaging barrier materials (material 3) were made using enzyme-modified starch. The barrier properties, ductility and biodegradability of the three materials were tested to screen out the most suitable modified starch. Three replicates were used in each group, and the weight of the barrier layer was 2g / ㎡.

[0042] 1) Test the barrier properties of three materials

[0043] Cut 10 specimens from the barriers made of three materials, with an area of ​​at least 50mm×150mm, and mark the test surface (i.e., barrier surface). According to the test method of GB / T 22805.2 "Determination of ester resistance of paper and paperboard", prepare KIT 1-12 test solutions of different oil resistance levels and number them. Place each specimen on a clean, flat test bench with the test surface facing up. Take a specimen and the test solution with the middle number, drop a drop of the test solution on the surface of the specimen at a distance of about 10mm from the test surface of the specimen, and start the stopwatch. After 15s, quickly wipe off the excess test solution with absorbent paper or cotton fabric, and immediately check the area where the test solution is dropped. If the area where the test solution is dropped becomes dark, the test endpoint is reached. If the test endpoint is obtained in the first test, repeat the above test steps on other areas of the same specimen with a lower numbered test solution until the test endpoint no longer appears. The highest number of the test solution that does not appear at the endpoint is taken as the ester resistance value of the specimen. The higher the ester resistance value, the higher the barrier property of the material.

[0044] From the results in Table 1, it can be seen that the barrier effect of material 2 is the best.

[0045] Table 1: Ester resistance values ​​of three barrier materials

[0046]

[0047] 2) Tensile strength

[0048] Cut the material sample into a size of 15mm in width and 150mm in length, fix it on the fixture, make sure the long axis of the sample is in a straight line with the axis of the testing machine, start the testing machine, and perform the tensile test at a tensile speed of 5mm / min. During the process, observe the deformation of the sample, and record the deformation of each material, as well as the tensile force value that reaches the breaking point. As shown in Table 2, the tensile strength of material 1 is the worst, and the tensile strength of material 2 is the best.

[0049] Table 2: Tensile strength of three barrier materials (Mpa)

[0050]

[0051] 3) Biodegradability test

[0052] Composting experiments were conducted using straw. Corn straw was added to three groups of barrier samples with the same specifications. Compost inoculum was added at a mass fraction of 8%. The temperature was maintained at 58±2°C, and the humidity was controlled between 50% and 55%. The experiment was conducted for 45 days, and the carbon dioxide release and degradation rate were recorded. As shown in Table 3, there was no significant difference in the average carbon dioxide release and degradation rate of the barriers made of the three materials (p>0.05), and the degradation rates were all above 95% after 45 days, confirming that the three material samples all had good biodegradability.

[0053] Table 3: Biodegradability of three barrier materials

[0054]

[0055] Taking into account the barrier properties, ductility and biodegradability of the three materials, the performance of material 2 is better than that of material 1 and material 3, so grafted starch is selected as the modified starch of the second layer.

[0056] Example 2: Preparation of packaging barrier material

[0057] like Figure 1 As shown, the fluorine-free, plastic-free, recyclable, compostable and degradable food packaging barrier material provided in this embodiment includes a first raw paper substrate layer, a second basic barrier layer and a third functional layer.

[0058] The second basic barrier layer is prepared using grafted starch, and the third functional layer is a water-based silicone coating.

[0059] The preparation method of grafted starch is as follows: add 1kg of water to the reactor, start stirring, pour in 1.5kg of corn starch, stir evenly and heat to 45±2°C, add 10g of ammonium persulfate initiator, but other organic and inorganic substances that form a redox system can also be used as initiators. After stirring for 30 minutes, slowly add 0.5kg of butyl acrylate, keep the temperature at 30°C for 2 to 4 hours, add hydroquinone with a final concentration of 5% (mass fraction) to terminate the reaction, and wash the reaction product with water several times to remove residual impurities. The washed starch is spray-dried to obtain grafted starch.

[0060] The specific steps for preparing packaging barrier materials are as follows:

[0061] Pour 18kg of water into the starch gelatinization kettle, start stirring, weigh 2kg of grafted starch and add it to the kettle. After stirring evenly, start heating to 95-98℃ and keep it at this temperature for 30 minutes. Then cool it to about 60-65℃ to form starch gelatinization liquid for use. Stirring is continuous during the whole process.

[0062] The starch gelatinized liquid is passed through a sizing system and evenly coated on the first layer of original paper substrate layer at a machine speed of 50-300 m / min and a drying temperature of 80-180°C to form a second basic barrier layer. The second barrier layer is rolled up after drying. The coating weight of the second barrier layer is 2±0.5 g / ㎡.

[0063] The third functional coating water-based silicone coating is placed in the coating machine trough, wherein the water-based silicone coating is manufactured by Elkem Silicones (Shanghai) Co., Ltd. under the product number BLUESIL TM EMUL 782 is sold as a composition of dimethylsiloxane, nonionic surfactants, alkylphenol ethoxylates and water.

[0064] The paper roll coated with the second base barrier layer is coated at a speed of 20m / min-180m / min, the functional coating water-based silicone coating is transferred to the second base barrier layer, and dried at 50-180℃ to form a third functional layer, which is then rolled up to prepare a new bio-based fluorine-free, plastic-free, recyclable, compostable and degradable food packaging barrier material.

[0065] The coating weight of the third functional layer is 1.5±0.5g / ㎡.

[0066] The barrier effect of the barrier material provided in this embodiment is as follows: Figure 2 As shown, its ester resistance value reaches 6, and the barrier surface of the second base barrier layer does not adhere to food and can withstand high temperatures of 220°C. Its raw material barrier layer comes from biomass to reduce carbon emissions and promote sustainable use of resources; the degradation product of the functional layer is silicon dioxide, which is environmentally friendly and has good recycling performance ( Figure 3 ), can be reused through recycling and regeneration processes to reduce resource waste and environmental pollution.

[0067] Example 3

[0068] The fluorine-free, plastic-free, recyclable, compostable and degradable food packaging barrier material provided in this embodiment includes a first raw paper substrate layer, a second basic barrier layer and a third functional layer.

[0069] The second basic barrier layer is prepared using grafted starch, and the third functional layer is a water-based acrylic coating. The water-based acrylic coating is a polymer emulsion formed by copolymerization of acrylic ester monomers. Different monomers and processes can be selected according to needs to prepare a water-based acrylic coating with functions such as waterproof and / or oil-proof and / or heat-sealing. The water-based acrylic coating used in this embodiment was produced by Covestro (Shanghai) Investment Co., Ltd. under the product number A-2092 for sale.

[0070] The functional coating water-based acrylic coating is placed in the coating machine trough, the water-based acrylic coating is coated at a speed of 20m / min-180m / min, the functional coating is transferred to the paper with the basic barrier layer, and the paper is dried and rolled at 50-180°C to prepare a new bio-based fluorine-free, plastic-free, recyclable, compostable and degradable food packaging barrier material. The barrier material provided by the present invention has a better barrier effect and an ester resistance value of more than 6.

[0071] Example 4

[0072] The fluorine-free, plastic-free, recyclable, compostable and degradable food packaging barrier material provided in this embodiment includes a first raw paper substrate layer, a second basic barrier layer and a third functional layer.

[0073] The second basic barrier layer is prepared using grafted starch, and the third functional layer is an inorganic coating.

[0074] The inorganic coating is composed of potassium silicate, silica sol, silicon dioxide, dispersant, defoamer and thickener. The inorganic coating used in this embodiment is sold by Sankeshu Coating Co., Ltd. under the item number SWI009. The functional coating inorganic coating is placed in the material trough of the coating machine, and the coating operation is carried out at a speed of 20m / min-180m / min. The functional coating is transferred to the paper with the basic barrier layer, and the paper is dried and rolled at 50-180°C to prepare a new bio-based fluorine-free plastic-free recyclable compostable food packaging barrier material. The barrier material provided by the present invention has a better barrier effect, an ester resistance value of more than 6, and a high temperature resistance of 220°C. Its raw materials come from biomass and inorganic materials to reduce carbon emissions and promote the sustainable use of resources. The degradation products of the barrier layer are water and carbon dioxide, and the degradation products of the functional layer are inorganic substances, which are pollution-free to the environment. The material has good recycling performance and can be reused through a recycling and regeneration process to reduce resource waste and environmental pollution.

[0075] The packaging barrier material prepared using modified starch in the present invention is a new type of packaging material, which combines multiple advantages such as bio-based, fluorine-free and plastic-free, recyclable, compostable and degradable, and can meet the requirements of modern food packaging for safety, environmental protection, sustainability and other aspects. It has broad application prospects and environmental protection characteristics. With the continuous advancement of technology and the continuous growth of market demand, this material will play an increasingly important role in the field of food packaging.

Claims

1. A fluorine-free, plastic-free, recyclable and degradable food packaging barrier material, characterized in that: The food packaging barrier material comprises a first base paper substrate layer, a second basic barrier layer and a third functional layer; wherein the second basic barrier layer is coated with grafted starch.

2. The food packaging barrier material according to claim 1, characterized in that: The preparation method of the grafted starch is as follows: water and corn starch are stirred evenly and then heated to 45±2°C, ammonium persulfate initiator is added for stirring reaction, butyl acrylate is added dropwise, constant temperature reaction is carried out at 30°C for 2-4 hours, hydroquinone solution is added to terminate the reaction, the reaction product is washed with water, and the washed starch is dried to obtain the grafted starch.

3. The food packaging barrier material according to claim 1, characterized in that: The first base paper layer is made of food contact paper with a grammage of 18-100 g / ㎡.

4. The food packaging barrier material according to claim 1, characterized in that: The second base barrier layer coating has a gram weight of 0.1-5 g / ㎡.

5. The food packaging barrier material according to claim 1, characterized in that: The third functional layer is selected from inorganic coatings, biodegradable coatings, water-based acrylic coatings or water-based silicone coatings.

6. The food packaging barrier material according to claim 1, characterized in that: The coating weight of the third functional layer is 0.1-5 g / ㎡.

7. The food packaging barrier material according to claim 1, characterized in that: The food packaging barrier material is prepared as follows: 1) Preparation of the second base barrier layer Pour water into the starch gelatinization kettle, start stirring, weigh the grafted starch and add it to the starch gelatinization kettle, stir evenly, and then start heating to 95-98°C, and keep it at this temperature for 30 minutes, then cool it down to about 60-65°C to form starch gelatinization liquid for use. 2) Preparation of the second base barrier layer The starch gelatinized liquid is evenly coated on the paper through the sizing system at a machine speed of 50-300m / min and a drying temperature of 80-180℃ to form the second basic barrier layer, and then rolled up after drying; 3) Functional coating The functional coating is placed in the coating machine trough, and the coating operation is carried out at a speed of 20m / min-180m / min. The functional coating is transferred to the paper with the basic barrier layer, and the paper is dried and rolled at 50-180℃ to prepare the food packaging barrier material.

8. Use of the food packaging barrier material according to claim 1 in preparing food packaging products.

9. A food packaging product, characterized in that: The food packaging barrier material according to claim 1 is used in the product.

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