High barrier food packaging paper and process for its production

Abstract

The application relates to the papermaking technical field, in particular to a high-barrier food packaging paper and a production process thereof. The application aims to solve the problem of how to reduce the cost while improving the barrier performance of the packaging paper. To this end, the production process of the high-barrier food packaging paper can reduce the fiber size, improve the fiber dispersion uniformity, strengthen the internal structure of the packaging paper and improve the barrier performance of the packaging paper by homogenizing the primary fiber slurry. In addition, the secondary fiber slurry, sodium alginate sol, alkyd resin and talcum powder are used as raw materials, the production cost is reduced, the barrier performance of the food packaging paper is improved, the oil resistance of the packaging paper is improved, and the tensile strength and breaking strength of the packaging paper are also improved.

Description

Technical Field

[0001] This invention relates to a high-barrier food packaging paper and its production process, belonging to the field of papermaking. Background Technology

[0002] Food packaging paper is the paper packaging material for ready-to-eat foods such as candy, popsicles, and pastries. Food packaging paper plays an irreplaceable role in protecting food, preventing contamination from external microorganisms or other substances, and preventing or reducing oxidation and other reactions. Therefore, packaging paper must have good barrier properties (water and oil resistant).

[0003] To achieve high barrier properties in packaging paper, surface sizing is typically applied, and oil-resistant agents are added to the sizing agent to enhance its oil-resistant effect. Many oil-resistant agents developed from natural polymers or fluorine-free agents have been developed and are also applied to the paper surface using sizing methods. However, these oil-resistant agents suffer from high usage and cost, hindering their widespread adoption. Summary of the Invention

[0004] The purpose of this invention is to provide a high-barrier food packaging paper and its manufacturing process, solving the problem of how to improve the barrier properties of packaging paper while reducing costs. To this end, this invention provides a manufacturing process for high-barrier food packaging paper, comprising the following steps:

[0005] a) The plant fiber is mixed with an alkaline solution and reacted, then filtered, washed and dried in sequence, water is added and mechanically pulped to obtain a primary fiber pulp.

[0006] b) After shearing the primary fiber pulp for 5-10 minutes, transfer it to a high-pressure homogenizer for homogenization to obtain the secondary fiber pulp;

[0007] c) Stir the secondary fiber slurry, sodium alginate sol, alkyd resin, and talc powder at 30-40℃ for 0.5-1h to obtain a mixed slurry;

[0008] d) The mixed pulp is sequentially processed into paper and dried to obtain the base paper;

[0009] e) The base paper is sizing and dried to obtain high-barrier food packaging paper.

[0010] In the preferred embodiment of the above production process, the preparation method of the sodium alginate sol includes adding tea polyphenols and sodium alginate to an acetic acid solution, stirring evenly, adjusting the pH value to 4-6 with an alkaline solution, and continuing to stir at 30-50℃ for 20-60 minutes to obtain sodium alginate sol.

[0011] In the preferred embodiment of the above production process, the mass ratio of tea polyphenols, sodium alginate, and acetic acid solution is (0.3-1):(1-5):100, and the mass concentration of acetic acid solution is 0.5-1.5%.

[0012] In the preferred embodiment of the above production process, the homogenization process specifically includes:

[0013] Cycle 2-4 times under a pressure of 40-50 MPa;

[0014] Cycle 1-3 times under a pressure of 20-30 MPa;

[0015] Cycle 1-3 times under a pressure of 30-40 MPa.

[0016] In the preferred technical solution of the above production process, the preparation method of the sizing agent used for sizing includes:

[0017] Solvents are added to alkyd resin, octenyl succinic anhydride, and lauramide propyl betaine. After stirring evenly, modified cellulose and modified cyclodextrin are added sequentially, and the reaction is carried out at 50-70℃ for 10-15 hours. Then, silane coupling agent is added, and the mixture is stirred at 40-50℃ for 2-4 hours to obtain the sizing agent.

[0018] In the preferred technical scheme of the above production process, the mass ratio of alkyd resin, octenyl succinic anhydride, lauramide propyl betaine, silane coupling agent, modified cellulose, and modified cyclodextrin is (1-3):(0.5-1):(0.3-0.6):(0.05-0.1):(0.1-0.5):(0.1-0.5).

[0019] In the preferred technical solution of the above production process, the preparation method of modified cellulose and modified cyclodextrin includes:

[0020] The cellulose suspension and cyclodextrin suspension were mixed and then sonicated. Stearic acid and sodium alginate were then added and sonicated again. The mixture was stirred in a water bath for 10-15 hours, centrifuged, and dried to obtain modified cellulose and modified cyclodextrin.

[0021] In the preferred technical solution of the above production process, the mass ratio of secondary fiber pulp, sodium alginate sol, alkyd resin and talc is 100:(10-20):(1-5):(1-5).

[0022] In the preferred embodiment of the above production process, the freeness of the primary fiber pulp is 60-70°SR; and / or

[0023] The mass concentration of the primary fiber pulp is 10-15%.

[0024] The present invention also provides a high-barrier food packaging paper, which is produced by the production process described in the above preferred technical solution.

[0025] Another objective of this invention is to provide a high-barrier food packaging paper and its production process. By homogenizing the primary fiber pulp, fiber size can be reduced, fiber dispersion uniformity can be improved, the internal structure of the packaging paper can be enhanced, and the barrier properties of the packaging paper can be improved. In addition, by using secondary fiber pulp, sodium alginate sol, alkyd resin, and talc as raw materials, the production cost is reduced, the barrier properties of the food packaging paper are improved, the oil resistance of the packaging paper is enhanced, and the tensile strength and burst strength of the packaging paper are also improved. Detailed Implementation

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0027] This invention provides a production process for high-barrier food packaging paper, characterized by comprising the following steps:

[0028] a) The plant fiber is mixed with an alkaline solution and reacted, then filtered, washed and dried in sequence, water is added and mechanically pulped to obtain a primary fiber pulp.

[0029] b) After shearing the primary fiber pulp for 5-10 minutes, transfer it to a high-pressure homogenizer for homogenization to obtain the secondary fiber pulp;

[0030] c) Stir the secondary fiber slurry, sodium alginate sol, alkyd resin, and talc powder at 30-40℃ for 0.5-1h to obtain a mixed slurry;

[0031] d) The mixed pulp is sequentially processed into paper and dried to obtain the base paper;

[0032] e) The base paper is sizing and dried to obtain high-barrier food packaging paper.

[0033] This application reduces fiber size and improves fiber dispersion uniformity by homogenizing the primary fiber pulp, thereby enhancing the internal structure and barrier properties of the packaging paper. Furthermore, using secondary fiber pulp, sodium alginate sol, alkyd resin, and talc as raw materials reduces production costs, improves the barrier properties of food packaging paper, enhances its oil resistance, and also increases its tensile strength and burst strength.

[0034] For step a), in this invention, the lignin structure of the plant fibers is destroyed by alkali treatment, and then separated from the fibers through filtration and washing. The primary fiber pulp obtained by mechanical pulping has a mass concentration of 10-15% and a freeness of 60-70°SR. Using primary fiber pulp with this freeness can improve the barrier performance of the device.

[0035] The plant fibers include wood fiber and bamboo fiber, and the mass ratio of wood fiber to bamboo fiber is (1-9):(9-1).

[0036] For step b), the primary fiber pulp undergoes a high-quality treatment, which includes treatment at 40-50 MPa for 5-10 minutes; at 20-30 MPa for 3-6 minutes; and at 30-40 MPa for 3-6 minutes. This high-quality treatment of the primary fiber pulp produces nanofibers of cellulose, thereby improving the barrier properties of the packaging paper.

[0037] For step c), using secondary fiber pulp, sodium alginate sol, alkyd resin, and talc as raw materials for packaging paper can improve the oil resistance, tensile strength, and bursting strength of the packaging paper. The mass ratio of secondary fiber pulp, sodium alginate sol, alkyd resin, and talc is 100:(10-20):(1-5):(1-5).

[0038] Sodium alginate sol can improve the antibacterial and antiseptic properties of food packaging paper. The preparation method of sodium alginate sol involves adding tea polyphenols and sodium alginate to an acetic acid solution, stirring until homogeneous, adjusting the pH to 4-6 with an alkaline solution, and continuing to stir at 30-50℃ for 20-60 minutes to obtain the sodium alginate sol. The mass ratio of tea polyphenols, sodium alginate, and acetic acid solution is (0.3-1):(1-5):100, and the mass concentration of the acetic acid solution is 0.5-1.5%.

[0039] Talc can improve the burst resistance of packaging paper, and its particle size is 100-200nm.

[0040] Alkyd resins can improve the tensile strength and bursting strength of packaging paper.

[0041] Step d) papermaking and drying are conventional techniques in this field and will not be described in detail here.

[0042] For step e), applying sizing to the surface of the base paper can improve the barrier properties of the packaging paper, as well as its tensile strength and bursting strength.

[0043] The preparation methods of the sizing agent used in sizing include:

[0044] Solvents are added to alkyd resin, octenyl succinic anhydride, and lauramide propyl betaine. After stirring evenly, modified cellulose and modified cyclodextrin are added sequentially, and the reaction is carried out at 50-70℃ for 10-15 hours. Then, silane coupling agent is added, and the mixture is stirred at 40-50℃ for 2-4 hours to obtain the sizing agent.

[0045] The mass ratio of alkyd resin, octenyl succinic anhydride, lauramide propyl betaine, silane coupling agent, modified cellulose, and modified cyclodextrin is (1-3):(0.5-1):(0.3-0.6):

[0046] (0.05-0.1): (0.1-0.5): (0.1-0.5).

[0047] Using alkyd resin in sizing agents can improve the peel strength between the sizing layer and the base paper. The carboxyl groups in octenyl succinic anhydride and lauramide propyl betaine can react with the hydroxyl groups in the alkyd resin to improve the film-forming effect of the sizing agent, thereby enhancing the barrier properties of the sizing layer.

[0048] In the above steps, the solvent can be any one of tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, or dimethyl sulfoxide.

[0049] The silane coupling agent is any one of ethyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, propyltrimethoxysilane, and propyltriethoxysilane.

[0050] The preparation methods for modified cellulose and modified cyclodextrin include:

[0051] Cellulose and cyclodextrin suspensions were mixed and ultrasonically treated. Stearic acid and sodium alginate were then added, and ultrasonication continued. The mixture was stirred in a water bath for 10-15 hours, centrifuged, and dried to obtain modified cellulose and modified cyclodextrin. The mass concentration of the cellulose suspension was 1-3%, and the mass concentration of the cyclodextrin suspension was 1-3%. The mass ratio of cellulose suspension, cyclodextrin suspension, stearic acid, and sodium alginate was (10-90):(10-90):(1-2):(1-5). Modification of cellulose and cyclodextrin improves the film-forming properties of the sizing agent, thereby ensuring the barrier properties of the packaging paper.

[0052] The present invention will be described in conjunction with the following embodiments.

[0053] Sodium alginate, alkyd resin, talc, tea polyphenols, octenyl succinic anhydride, lauramide propyl betaine, cellulose, cyclodextrin, silane coupling agent, and solvent used in this application are all commercially available.

[0054] The silane coupling agent is ethyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, propyltrimethoxysilane, or propyltriethoxysilane, all of which were purchased from THIAI (Shanghai) Chemical Industry Development Co., Ltd.

[0055] The solvents were tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, or dimethyl sulfoxide, all purchased from Jinan Chuangshi Chemical Co., Ltd.

[0056] Sodium alginate was purchased from Shandong Jingyun Food Ingredients Co., Ltd.

[0057] The alkyd resin was purchased from Shandong Lingsai Coatings Co., Ltd., 389-9A.

[0058] The talc powder was purchased from Danhai Chemical Stone Powder Co., Ltd. in Haicheng City.

[0059] The tea polyphenols were purchased from Xi'an Best Biotechnology Co., Ltd.

[0060] Octenyl succinic anhydride was purchased from Guangzhou Chuancan Chemical Co., Ltd.

[0061] Lauroamide propyl betaine was purchased from Shengci (Hubei) Industrial Materials Co., Ltd.

[0062] The cellulose used was either microcrystalline cellulose or carboxymethyl cellulose, both purchased from Guangzhou Huayu Biotechnology Co., Ltd.

[0063] The cyclodextrin was α-cyclodextrin, purchased from Shanghai Baisifu Food Development Co., Ltd.

[0064] In addition, both wood fiber and bamboo fiber are obtained by processing wood or bamboo raw materials into small pieces, then steaming the materials, followed by hot grinding, drying, and sieving to obtain wood fiber powder or bamboo fiber powder. The moisture content of the wood fiber powder or bamboo fiber powder is then controlled to be 40-50% (by mass). Finally, the wood fiber powder or bamboo fiber powder is treated with laccase or white rot fungi to obtain wood fiber powder or bamboo fiber powder.

[0065] Example 1

[0066] The production process of high-barrier food packaging paper includes the following steps:

[0067] a) The plant fiber is mixed with alkaline solution and reacted, then filtered, washed and dried in sequence, water is added and mechanically pulped to obtain a primary fiber pulp with a mass concentration of 11% and a freeness of 60°SR.

[0068] The plant fiber includes wood fiber and bamboo fiber in a mass ratio of 1:1, and the alkali solution is a sodium hydroxide solution with a mass concentration of 2%.

[0069] b) After shearing the primary fiber slurry for 7 minutes, transfer it to a high-pressure homogenizer for homogenization to obtain the secondary fiber slurry;

[0070] The homogenization process includes cycling 3 times at a pressure of 45 MPa; cycling 2 times at a pressure of 25 MPa; and cycling 2 times at a pressure of 35 MPa.

[0071] c) Stir the secondary fiber slurry, sodium alginate sol, alkyd resin, and talc powder at 40°C for 0.5 h to obtain a mixed slurry;

[0072] The mass ratio of secondary fiber pulp, sodium alginate sol, alkyd resin, and talc is 100:18:2:4.

[0073] The sodium alginate sol was prepared by adding tea polyphenols and sodium alginate to an acetic acid solution, stirring until homogeneous, adjusting the pH to 5 with an alkaline solution, and continuing to stir at 40°C for 40 minutes to obtain the sodium alginate sol. The mass ratio of tea polyphenols, sodium alginate, and acetic acid solution was 0.4:2:100, and the mass concentration of the acetic acid solution was 1.2%. The particle size of the talc powder was 100-200 nm.

[0074] d) The mixed pulp is sequentially processed into paper and dried to obtain the base paper;

[0075] e) The base paper is sizing and dried to obtain high-barrier food packaging paper;

[0076] The preparation methods of the sizing agent used in sizing include:

[0077] Tetrahydrofuran was added to alkyd resin, octenyl succinic anhydride, and lauramide propyl betaine. After stirring evenly, modified cellulose and modified cyclodextrin were added sequentially, and the reaction was carried out at 55℃ for 13 hours. Then, ethyltrimethoxysilane was added, and the mixture was stirred at 43℃ for 3.5 hours to obtain a sizing agent. The mass ratio of alkyd resin, octenyl succinic anhydride, lauramide propyl betaine, ethyltrimethoxysilane, modified cellulose, and modified cyclodextrin was 2.5:0.9:0.55:0.09:0.25:0.35.

[0078] Methods for preparing modified cellulose and modified cyclodextrin include:

[0079] Cellulose and cyclodextrin suspensions were mixed and ultrasonicated. After 20 minutes, stearic acid and sodium alginate were added, and ultrasonication continued for another 30 minutes. The mixture was then stirred in a water bath at 45°C for 12 hours. After centrifugation and drying, modified cellulose and modified cyclodextrin were obtained. The mass concentration of the cellulose suspension was 1.5%, and the mass concentration of the cyclodextrin suspension was 2.5%. The mass ratio of cellulose suspension, cyclodextrin suspension, stearic acid, and sodium alginate was 90:10:1.5:2.

[0080] Example 2

[0081] The production process of high-barrier food packaging paper includes the following steps:

[0082] a) The plant fiber is mixed with alkaline solution and reacted, then filtered, washed and dried in sequence, water is added and mechanically pulped to obtain a primary fiber pulp with a mass concentration of 13% and a freeness of 65°SR.

[0083] The plant fiber includes wood fiber and bamboo fiber in a mass ratio of 1:1, and the alkali solution is a 4% potassium hydroxide solution.

[0084] b) After shearing the primary fiber pulp for 10 minutes, transfer it to a high-pressure homogenizer for homogenization to obtain the secondary fiber pulp;

[0085] The homogenization process includes cycling 3 times at a pressure of 50 MPa; cycling 2 times at a pressure of 30 MPa; and cycling once at a pressure of 40 MPa.

[0086] c) Stir the secondary fiber slurry, sodium alginate sol, alkyd resin, and talc powder at 35°C for 1 hour to obtain a mixed slurry;

[0087] The mass ratio of secondary fiber pulp, sodium alginate sol, alkyd resin, and talc is 100:12:4:3;

[0088] The sodium alginate sol was prepared by adding tea polyphenols and sodium alginate to an acetic acid solution, stirring until homogeneous, adjusting the pH to 6 with an alkaline solution, and continuing to stir at 50°C for 45 minutes to obtain the sodium alginate sol. The mass ratio of tea polyphenols, sodium alginate, and acetic acid solution was 0.6:4:100, and the mass concentration of the acetic acid solution was 1.2%. The particle size of the talc powder was 100-200 nm.

[0089] d) The mixed pulp is sequentially processed into paper and dried to obtain the base paper;

[0090] e) The base paper is sizing and dried to obtain high-barrier food packaging paper;

[0091] The preparation methods of the sizing agent used in sizing include:

[0092] N,N-dimethylformamide was added to alkyd resin, octenyl succinic anhydride, and lauramide propyl betaine. After stirring evenly, modified cellulose and modified cyclodextrin were added sequentially, and the mixture was reacted at 55℃ for 13 hours. Then, methyltriethoxysilane was added, and the mixture was stirred at 40℃ for 4 hours to obtain a sizing agent. The mass ratio of alkyd resin, octenyl succinic anhydride, lauramide propyl betaine, methyltriethoxysilane, modified cellulose, and modified cyclodextrin was 2.5:0.75:0.45:0.08:0.4:0.2.

[0093] Methods for preparing modified cellulose and modified cyclodextrin include:

[0094] Cellulose and cyclodextrin suspensions were mixed and ultrasonicated. After 10 minutes, stearic acid and sodium alginate were added, and ultrasonication continued for another 30 minutes. The mixture was then stirred in a 50°C water bath for 14 hours. After centrifugation and drying, modified cellulose and modified cyclodextrin were obtained. The mass concentration of the cellulose suspension was 1%, and the mass concentration of the cyclodextrin suspension was 1%. The mass ratio of cellulose suspension, cyclodextrin suspension, stearic acid, and sodium alginate was 40:60:1.8:4.

[0095] Example 3

[0096] The production process of high-barrier food packaging paper includes the following steps:

[0097] a) The plant fiber is mixed with alkaline solution and reacted, then filtered, washed and dried in sequence, water is added and mechanically pulped to obtain a primary fiber pulp with a mass concentration of 12% and a freeness of 65°SR.

[0098] The plant fiber includes wood fiber and bamboo fiber in a mass ratio of 1:1, and the alkali solution is a sodium hydroxide solution with a mass concentration of 2%.

[0099] b) After shearing the primary fiber pulp for 5 minutes, transfer it to a high-pressure homogenizer for homogenization to obtain the secondary fiber pulp;

[0100] The homogenization process includes cycling 3 times at a pressure of 40 MPa; cycling 2 times at a pressure of 20 MPa; and cycling 2 times at a pressure of 30 MPa.

[0101] c) Stir the secondary fiber slurry, sodium alginate sol, alkyd resin, and talc powder at 30°C for 0.5 h to obtain a mixed slurry;

[0102] The mass ratio of secondary fiber pulp, sodium alginate sol, alkyd resin, and talc is 100:12:3:3;

[0103] The sodium alginate sol is prepared by adding tea polyphenols and sodium alginate to an acetic acid solution, stirring until homogeneous, adjusting the pH to 5 with an alkaline solution, and continuing to stir at 40°C for 30 minutes to obtain the sodium alginate sol. The mass ratio of tea polyphenols, sodium alginate, and acetic acid solution is 0.5:3:100, the mass concentration of the acetic acid solution is 1%, and the particle size of the talc is 100-200 nm.

[0104] d) The mixed pulp is sequentially processed into paper and dried to obtain the base paper;

[0105] e) The base paper is sizing and dried to obtain high-barrier food packaging paper;

[0106] The preparation methods of the sizing agent used in sizing include:

[0107] N,N-dimethylacetamide was added to alkyd resin, octenyl succinic anhydride, and lauramide propyl betaine. After stirring evenly, modified cellulose and modified cyclodextrin were added sequentially, and the mixture was reacted at 60℃ for 12 hours. Then, ethyltriethoxysilane was added, and the mixture was stirred at 45℃ for 3 hours to obtain a sizing agent. The mass ratio of alkyd resin, octenyl succinic anhydride, lauramide propyl betaine, ethyltriethoxysilane, modified cellulose, and modified cyclodextrin was 2:0.7:0.4:0.08:0.3:0.3.

[0108] Methods for preparing modified cellulose and modified cyclodextrin include:

[0109] Cellulose and cyclodextrin suspensions were mixed and ultrasonicated for 20 minutes. Stearic acid and sodium alginate were then added, and ultrasonication continued for another 20 minutes. The mixture was stirred in a 50°C water bath for 10-15 hours. After centrifugation and drying, modified cellulose and modified cyclodextrin were obtained. The mass concentration of the cellulose suspension was 2%, and the mass concentration of the cyclodextrin suspension was 2%. The mass ratio of cellulose suspension, cyclodextrin suspension, stearic acid, and sodium alginate was 50:50:1.5:3.

[0110] Example 4

[0111] The production process of high-barrier food packaging paper includes the following steps:

[0112] a) The plant fiber is mixed with alkaline solution and reacted, then filtered, washed and dried in sequence, water is added and mechanically pulped to obtain a primary fiber pulp with a mass concentration of 10% and a freeness of 65°SR.

[0113] The plant fiber includes wood fiber and bamboo fiber in a mass ratio of 1:1, and the alkali solution is a 1% potassium hydroxide solution.

[0114] b) After shearing the primary fiber pulp for 5 minutes, transfer it to a high-pressure homogenizer for homogenization to obtain the secondary fiber pulp;

[0115] The homogenization process includes cycling 4 times at a pressure of 40 MPa; cycling 3 times at a pressure of 20 MPa; and cycling 3 times at a pressure of 30 MPa.

[0116] c) Stir the secondary fiber slurry, sodium alginate sol, alkyd resin, and talc powder at 30°C for 1 hour to obtain a mixed slurry;

[0117] The mass ratio of secondary fiber pulp, sodium alginate sol, alkyd resin, and talc is 100:10:5:1;

[0118] The sodium alginate sol was prepared by adding tea polyphenols and sodium alginate to an acetic acid solution, stirring until homogeneous, adjusting the pH to 4 with an alkaline solution, and continuing to stir at 50°C for 20 minutes to obtain the sodium alginate sol. The mass ratio of tea polyphenols, sodium alginate, and acetic acid solution was 0.3:1:100, and the mass concentration of the acetic acid solution was 0.5%. The particle size of the talc powder was 100-200 nm.

[0119] d) The mixed pulp is sequentially processed into paper and dried to obtain the base paper;

[0120] e) The base paper is sizing and dried to obtain high-barrier food packaging paper;

[0121] The preparation methods of the sizing agent used in sizing include:

[0122] Dimethyl sulfoxide was added to alkyd resin, octenyl succinic anhydride, and lauramide propyl betaine. After stirring evenly, modified cellulose and modified cyclodextrin were added sequentially, and the reaction was carried out at 50℃ for 10 h. Then, propyltrimethoxysilane was added, and the mixture was stirred at 40℃ for 4 h to obtain a sizing agent. The mass ratio of alkyd resin, octenyl succinic anhydride, lauramide propyl betaine, propyltrimethoxysilane, modified cellulose, and modified cyclodextrin was 1:0.5:0.3:0.05:0.1:0.5.

[0123] Methods for preparing modified cellulose and modified cyclodextrin include:

[0124] Cellulose and cyclodextrin suspensions were mixed and ultrasonicated for 10 minutes. Stearic acid and sodium alginate were then added, and ultrasonication continued for another 10 minutes. The mixture was stirred in a 60°C water bath for 15 hours. After centrifugation and drying, modified cellulose and modified cyclodextrin were obtained. The mass concentration of the cellulose suspension was 3%, and the mass concentration of the cyclodextrin suspension was 1%. The mass ratio of cellulose suspension, cyclodextrin suspension, stearic acid, and sodium alginate was 10:90:1:1.

[0125] Example 5

[0126] The production process of high-barrier food packaging paper includes the following steps:

[0127] a) The plant fiber is mixed with alkaline solution and reacted, then filtered, washed and dried in sequence, water is added and mechanically pulped to obtain a primary fiber pulp with a mass concentration of 15% and a freeness of 70°SR.

[0128] The plant fiber includes wood fiber and bamboo fiber in a mass ratio of 1:1, and the alkali solution is a 5% sodium hydroxide solution.

[0129] b) After shearing the primary fiber pulp for 10 minutes, transfer it to a high-pressure homogenizer for homogenization to obtain the secondary fiber pulp;

[0130] The homogenization process includes cycling twice at a pressure of 50 MPa, once at a pressure of 30 MPa, and once at a pressure of 40 MPa.

[0131] c) Stir the secondary fiber slurry, sodium alginate sol, alkyd resin, and talc powder at 40°C for 0.5 minutes to obtain a mixed slurry;

[0132] The mass ratio of secondary fiber pulp, sodium alginate sol, alkyd resin, and talc is 100:20:1:5;

[0133] The sodium alginate sol was prepared by adding tea polyphenols and sodium alginate to an acetic acid solution, stirring until homogeneous, adjusting the pH to 6 with an alkaline solution, and continuing to stir at 30°C for 60 minutes to obtain the sodium alginate sol. The mass ratio of tea polyphenols, sodium alginate, and acetic acid solution was 1:5:100, and the mass concentration of the acetic acid solution was 1.5%. The particle size of the talc powder was 100-200 nm.

[0134] d) The mixed pulp is sequentially processed into paper and dried to obtain the base paper;

[0135] e) The base paper is sizing and dried to obtain high-barrier food packaging paper;

[0136] The preparation methods of the sizing agent used in sizing include:

[0137] N,N-dimethylacetamide was added to alkyd resin, octenyl succinic anhydride, and lauramide propyl betaine. After stirring evenly, modified cellulose and modified cyclodextrin were added sequentially, and the mixture was reacted at 70°C for 15 hours. Then, propyltriethoxysilane was added, and the mixture was stirred at 50°C for 2 hours to obtain a sizing agent. The mass ratio of alkyd resin, octenyl succinic anhydride, lauramide propyl betaine, propyltriethoxysilane, modified cellulose, and modified cyclodextrin was 3:1:0.6:0.1:0.5:0.1.

[0138] Methods for preparing modified cellulose and modified cyclodextrin include:

[0139] Cellulose and cyclodextrin suspensions were mixed and ultrasonicated for 130 min. Stearic acid and sodium alginate were then added, and ultrasonication continued for another 30 min. The mixture was stirred in a 40°C water bath for 10-15 h. After centrifugation and drying, modified cellulose and modified cyclodextrin were obtained. The mass concentration of the cellulose suspension was 1%, and the mass concentration of the cyclodextrin suspension was 3%. The mass ratio of cellulose suspension, cyclodextrin suspension, stearic acid, and sodium alginate was 90:50:2:5.

[0140] Comparative Example 1

[0141] The only difference from Example 1 is step a):

[0142] The freeness of the primary fiber pulp is 40%.

[0143] Comparative Example 2

[0144] The only difference from Example 1 is step a):

[0145] Plant fibers include only wood fibers.

[0146] Comparative Example 3

[0147] The only difference from Example 1 is step a):

[0148] Plant fibers include only bamboo fiber.

[0149] Comparative Example 4

[0150] The only difference from Example 2 is step b):

[0151] No homogenization process was performed.

[0152] Comparative Example 5

[0153] The only difference from Example 2 is step b):

[0154] The homogenization process involved three cycles at a pressure of 50 MPa and one cycle at a pressure of 40 MPa.

[0155] Comparative Example 6

[0156] The only difference from Example 2 is step b):

[0157] The homogenization process included three cycles at 30 MPa, two cycles at 40 MPa, and one cycle at 50 MPa.

[0158] Comparative Example 7

[0159] The only difference from Example 2 is step b):

[0160] The homogenization process included three cycles at 30 MPa, two cycles at 50 MPa, and one cycle at 40 MPa.

[0161] Comparative Example 8

[0162] The only difference from Example 3 is step c):

[0163] The sodium alginate sol is prepared by adding sodium alginate to an acetic acid solution, stirring until homogeneous, adjusting the pH to 5 with an alkaline solution, and continuing to stir at 40°C for 30 minutes to obtain the sodium alginate sol. The mass ratio of sodium alginate to acetic acid solution is 3:100.

[0164] Comparative Example 9

[0165] The only difference from Example 3 is step c):

[0166] Sodium alginate sol was not added to the mixed slurry.

[0167] Comparative Example 10

[0168] The only difference from Example 4 is step e):

[0169] Cellulose and cyclodextrin were not modified, and the mass ratio of alkyd resin, octenyl succinic anhydride, lauramide propyl betaine, methyltriethoxysilane, cellulose, and cyclodextrin was 2:0.7:0.4:0.08:0.3:0.3.

[0170] Comparative Example 11

[0171] The only difference from Example 4 is step e):

[0172] The cellulose was not modified, and the mass ratio of alkyd resin, octenyl succinic anhydride, lauramide propyl betaine, methyltriethoxysilane, cellulose, and modified cyclodextrin was 2:0.7:0.4:0.08:0.3:0.3.

[0173] Comparative Example 12

[0174] The only difference from Example 4 is step e):

[0175] The cyclodextrin was not modified, and the mass ratio of alkyd resin, octenyl succinic anhydride, lauramide propyl betaine, methyltriethoxysilane, modified cellulose, and cyclodextrin was 2:0.7:0.4:0.08:0.3:0.3.

[0176] Comparative Example 13

[0177] The only difference from Example 5 is step c):

[0178] Without the addition of alkyd resin, the mass ratio of secondary fiber pulp, sodium alginate sol, alkyd resin, and talc is 100:10:1.

[0179] Comparative Example 14

[0180] The only difference from Example 5 is step e):

[0181] Without adding octenyl succinic anhydride and lauramide propyl betaine, dimethyl sulfoxide was added to the alkyd resin, and after stirring evenly, modified cellulose and modified cyclodextrin were added sequentially, and the reaction was carried out at 50°C for 10 hours. Then, propyltrimethoxysilane was added, and the mixture was stirred at 40°C for 4 hours to obtain the sizing agent. The mass ratio of alkyd resin, propyltrimethoxysilane, modified cellulose, and modified cyclodextrin was 1:0.05:0.1:0.5.

[0182] The high-barrier food packaging papers prepared in Examples 1-5 and Comparative Examples 1-14 were tested for tensile strength, burst strength, oil absorption, water absorption and dust content in accordance with QB T1014-2010. The results are shown in Table 1.

[0183]

[0184] As can be seen from the experimental data in Table 1, the high-barrier food packaging paper prepared in Examples 1-5 is superior to the high-barrier food packaging paper prepared in Comparative Documents 1-14 in terms of tensile strength, burst strength, oil absorption, water absorption and dust content.

[0185] Those skilled in the art will understand that although some embodiments described herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, any of the claimed embodiments in the claims of this application can be used in any combination.

[0186] It should be noted that although the detailed steps of the method of this application have been described in detail above, those skilled in the art can combine, split and rearrange the above steps without departing from the basic principles of this application. Such modified technical solutions do not change the basic concept of this application and therefore fall within the protection scope of this application.

[0187] The technical solutions of this application have now been described. However, it will be readily understood by those skilled in the art that the scope of protection of this application is obviously not limited to these specific embodiments. Without departing from the principles of this application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions resulting from these changes or substitutions will all fall within the scope of protection of this application.

Claims

1. A production process for high-barrier food packaging paper, characterized in that, Includes the following steps: a) The plant fibers are mixed with alkaline solution and reacted, then filtered, washed and dried in sequence, water is added and mechanically pulped to obtain primary fiber pulp; wherein the plant fibers include wood fiber and bamboo fiber, and the mass of wood fiber to bamboo fiber is (1-9): (9-1); b) After shearing the primary fiber pulp for 5-10 minutes, transfer it to a high-pressure homogenizer for homogenization to obtain the secondary fiber pulp; c) Stir the secondary fiber slurry, sodium alginate sol, alkyd resin, and talc powder at 30-40℃ for 0.5-1h to obtain a mixed slurry; d) The mixed pulp is sequentially processed into paper and dried to obtain the base paper; e) The base paper is sizing and dried to obtain high-barrier food packaging paper; The preparation method of the sodium alginate sol includes adding tea polyphenols and sodium alginate to an acetic acid solution, stirring evenly, adjusting the pH value to 4-6 with an alkaline solution, and continuing to stir at 30-50℃ for 20-60 minutes to obtain sodium alginate sol. The mass ratio of tea polyphenols, sodium alginate, and acetic acid solution is (0.3-1):(1-5):100, and the mass concentration of the acetic acid solution is 0.5-1.5%. The homogenization process specifically includes: Cycle 2-4 times under a pressure of 40-50 MPa; Cycle 1-3 times under a pressure of 20-30 MPa; Cycle 1-3 times under a pressure of 30-40 MPa; The preparation methods of the sizing agent used in sizing include: Solvent is added to alkyd resin, octenyl succinic anhydride, and lauramide propyl betaine. After stirring evenly, modified cellulose and modified cyclodextrin are added in sequence, and the reaction is carried out at a temperature of 50-70℃ for 10-15 hours. Then, silane coupling agent is added, and the mixture is stirred at 40-50℃ for 2-4 hours to obtain sizing agent. The mass ratio of alkyd resin, octenyl succinic anhydride, lauramide propyl betaine, silane coupling agent, modified cellulose, and modified cyclodextrin is (1-3):(0.5-1):(0.3-0.6):(0.05-0.1):(0.1-0.5):(0.1-0.5). Methods for preparing modified cellulose and modified cyclodextrin include: Cellulose suspension and cyclodextrin suspension were mixed and ultrasonicated. Then stearic acid and sodium alginate were added and ultrasonication was continued. The mixture was stirred in a water bath for 10-15 hours. After centrifugation and drying, modified cellulose and modified cyclodextrin were obtained. The mass ratio of secondary fiber pulp, sodium alginate sol, alkyd resin, and talc is 100:(10-20):(1-5):(1-5); The freeness of the primary fiber pulp is 60-70°SR; the mass concentration of the primary fiber pulp is 10-15%.

2. A high-barrier food packaging paper, characterized in that, It is produced by the production process described in claim 1.

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