Environmentally friendly ultra-high barrier packaging paper and preparation method thereof

Abstract

This application relates to the technical field of packaging materials, specifically disclosing an environmentally friendly ultra-high barrier packaging paper and a method for preparing the same. The environmentally friendly ultra-high barrier packaging paper comprises a base paper layer, with high-barrier layers disposed on both sides of the base paper layer, a metal layer disposed on the outer side of the high-barrier layer away from the base paper layer, and a coating disposed on the outer side of the metal layer away from the high-barrier layer. The high-barrier layer is made from the following raw materials in parts by weight: 40-50 parts polyvinyl alcohol; 15-25 parts polyamide; 10-25 parts ethylene-vinyl alcohol copolymer; 4-8 parts barrier filler; and 5-9 parts modified mixed fiber. The environmentally friendly ultra-high barrier packaging paper of this application exhibits excellent bonding stability between the base paper layer and the high-barrier layer when affected by ambient temperature changes, resulting in high overall application quality.

Description

Technical Field

[0001] The present application relates to the technical field of packaging materials, and more specifically, to an environmentally friendly ultra-high barrier packaging paper and a preparation method thereof. Background Art

[0002] High-barrier packaging is a type of packaging material that has good oxygen and water barriers and high permeability, and can maintain quality, preserve freshness, and extend shelf life. Plastics and paper, plastic, and aluminum composite packaging materials are commonly used at home and abroad. Among them, polyamide (PA, also known as copolymer nylon), polyacrylonitrile (PAN), polyvinyl alcohol (PVA), polyvinyl chloride (PVC), polyethylene terephthalate (PET), polyvinylidene chloride (PVDC), and ethylene-vinyl alcohol copolymer (EVOH) are all commonly used high-barrier packaging materials.

[0003] High-barrier packaging paper is made from a paper-based material coated with a water-based barrier coating, making it recyclable and biodegradable, making its use more environmentally friendly. For example, Chinese invention patent application publication number CN115008853A discloses an easily recyclable high-barrier paper-aluminum composite packaging material and its preparation method. This packaging material has a multi-layer structure, consisting of a paper base and an aluminum foil layer bonded together by an adhesive. A coating layer is applied to both the paper base and the aluminum foil. The coating layer is composed of a biodegradable emulsion composed of one or more resins selected from polybutylene adipate / terephthalate, polylactic acid, polybutylene succinate, polycaprolactone, polyamide, and ethylene-vinyl alcohol copolymer. This packaging material possesses the advantages of high water solubility and easy degradation, significantly reducing the difficulty of recycling the aluminum foil. Furthermore, the presence of the aluminum foil and coating layer imparts excellent gas barrier properties to the material.

[0004] Regarding the above-mentioned related technologies, the inventors believe that the paper base layer is mostly processed and formed base paper that is used directly. The base paper itself is a porous fiber structure with holes at the microscopic level. After the coating layer material is adhered and fixed to the base paper, it will fill the holes on the surface of the base paper. When used in an environment with frequent temperature changes, the coating layer material expands and contracts due to changes in internal stress, causing the fiber structure at the holes of the base paper to undergo irreversible changes and creating gaps between the coating layer material, which in turn greatly reduces the bonding between the coating layer material and the base paper, affecting the stability of the packaging material during application.

[0005] Therefore, it is urgent to propose a solution to solve the above technical problems. Summary of the Invention

[0006] In order to improve the bonding stability between base paper and its surface coating in an environment with frequent temperature changes, the present application provides an environmentally friendly ultra-high barrier packaging paper and a preparation method thereof.

[0007] In a first aspect, the present application provides an environmentally friendly ultra-high barrier packaging paper, which adopts the following technical solution:

[0008] An environmentally friendly ultra-high barrier packaging paper comprises a base paper layer, high-barrier layers are provided on both sides of the base paper layer, a metal layer is provided on the outer side of the high-barrier layer away from the base paper layer, and a coating is provided on the outer side of the metal layer away from the high-barrier layer. The high-barrier layer is made of raw materials containing the following parts by weight:

[0009] 40-50 parts of polyvinyl alcohol;

[0010] Polyamide 15-25 parts;

[0011] 10-25 parts of ethylene-vinyl alcohol copolymer;

[0012] 4-8 parts of barrier filler;

[0013] 5-9 parts of modified mixed fiber;

[0014] The modified mixed fiber is prepared by the following steps:

[0015] S1, mixing hyaluronic acid chitosan with saturated sodium bicarbonate solution to obtain a treatment solution, then taking a fiber raw material and immersing it in the treatment solution, and finally taking it out and drying it to obtain a pretreated fiber raw material;

[0016] S2, treating the pretreated fiber raw material with a potassium permanganate solution, then mixing with acrylic acid and sulfuric acid for reaction, boiling, filtering, and drying the obtained grafted product, and then surface-treating it with a silane coupling agent, and drying to obtain a modified mixed fiber;

[0017] The fiber raw material consists of silk fiber and bamboo fiber in a weight ratio of (0.2-0.6):1.

[0018] By adopting the above technical solution, during the modification process of the fiber raw material, the fiber is first treated with a treatment liquid. By utilizing the action of hyaluronic acid chitosan and saturated sodium bicarbonate solution, the affinity and adhesion of the fiber can be improved, and based on the fiber-forming effect of chitosan, small fibrillated tentacles are formed on the fiber; then, after treatment with potassium permanganate, the fiber is grafted with a mixed reaction of acrylic acid and sulfuric acid, so that the overall strength of the fiber is improved, and the bonding between the fiber and other raw materials in the high-barrier layer is also significantly improved; finally, the surface is treated with a silane coupling agent, and the durability and water resistance of the fiber are improved by forming a silicon-oxygen bond cross-linking layer; finally, a modified hybrid fiber is obtained. When the modified mixed fiber is used in the high-barrier layer, it can be tightly combined with the fiber structure in the holes of the base paper layer. While entangled and hooked with each other, the modified mixed fiber can also act as a skeleton and bridge at the junction of the high-barrier layer and the base paper layer; when the high-barrier layer expands and contracts due to changes in ambient temperature, the modified mixed fiber and the fiber structure of the base paper layer can exert excellent mutual pulling and strain adjustment effects, so that the bonding strength between the high-barrier layer and the base paper layer maintains excellent stability, thereby making the environmentally friendly ultra-high barrier packaging paper have stable and excellent application effects.

[0019] Preferably, in step S2, the concentration of the potassium permanganate solution is 0.05-0.06 mol / L, the reaction concentration of acrylic acid is 3.5-4.5 mol / L, and the reaction concentration of sulfuric acid is 0.5-0.6 mol / L.

[0020] By adopting the above technical solution and selecting the above concentration substances, acrylic acid can be grafted relatively evenly onto the fiber surface during the treatment process, and the grafting rate of acrylic acid is also relatively high. As a result, when the final modified mixed fiber acts as a connecting skeleton and bridge, when the high barrier layer expands and contracts due to changes in ambient temperature, it can play an excellent role in maintaining the stability of the bonding strength between the high barrier layer and the base paper layer. As a result, the final environmentally friendly ultra-high barrier packaging paper has higher quality.

[0021] Preferably, the fiber raw material consists of silk fiber and bamboo fiber in a weight ratio of 0.5:1.

[0022] By adopting the above technical solution, the silk fibers and bamboo fibers with no weight ratio as fiber raw materials, after being applied as modified mixed fibers, not only form cross-network structures with different depths and are closely integrated with the fiber structure of the base paper layer, but also form a gradient pulling and strain adjustment system. The high-barrier layer can perfectly adapt to and play an excellent role in different expansion and contraction degrees, thereby maintaining a tight and stable combination between the high-barrier layer and the base paper layer, ensuring that the environmentally friendly ultra-high barrier packaging paper has relatively excellent stability during the application process.

[0023] Preferably, the modified mixed fiber is blended with polyester fiber before use, and the blending weight ratio of the modified mixed fiber to the polyester fiber is (2-5):1.

[0024] By adopting the above technical solution, polyester fiber and modified mixed fiber are blended and then applied to the high-barrier layer. Due to the presence of polyester fiber, the low strength of the modified mixed fiber can be further compensated, so that the combination of the two can better cope with the changes in the fiber structure of the base layer; at the same time, polyester fiber and modified mixed fiber can bring excellent coordination effect. In the process of pulling and strain adjusting the fiber structure of the base paper layer, the depolymerization effect of the blended system can show stronger applicability, so that the high-barrier layer and the base paper layer can show stronger resistance to damage when affected by ambient temperature changes, and thus are better in maintaining the stability of bonding strength, so that the application quality of the final environmentally friendly ultra-high barrier packaging paper is significantly improved.

[0025] Preferably, the blending weight ratio of the modified mixed fiber and the polyester fiber is 3.5:1.

[0026] By adopting the above technical solution, after the modified mixed fiber and polyester fiber in the above weight ratio are blended, the application effect is better, and the high barrier layer and the base paper layer can maintain a relatively stable and excellent combination in an environment with temperature changes, thereby obtaining an environmentally friendly ultra-high barrier packaging paper with better application quality.

[0027] Preferably, 3-7 parts by weight of a functional additive are added to the raw materials of the high barrier layer. The functional additive consists of isocyanate and porous ceramic powder, and the weight ratio of isocyanate to porous ceramic powder is 1:(1.8-2.4).

[0028] By adopting the above-mentioned technical solution, isocyanate can improve the interfacial compatibility between the modified mixed fiber and other raw materials. When it is used in combination with porous ceramic powder, part of the modified mixed fiber is penetrated into the pore size of the porous ceramic powder with the help of isocyanate, and then the porous ceramic powder is used as an anchor point in the high-barrier layer. In this way, the bonding stability between the high-barrier layer and the base paper layer can be greatly improved, and the ability to cope with changes in ambient temperature is stronger, thereby significantly improving the application quality of the environmentally friendly ultra-high barrier packaging paper.

[0029] Preferably, the weight ratio of the isocyanate to the porous ceramic powder is 1:2.

[0030] By adopting the above technical solution, the isocyanate and porous ceramic powder in the above weight ratio, when used in combination with the modified mixed fiber, have relatively excellent corresponding effects, and the environmentally friendly ultra-high barrier packaging paper finally obtained also has better overall quality.

[0031] Preferably, the barrier filler is one or a combination of zeolite, clay, silica and mica.

[0032] By adopting the above technical solution, the above types of fillers can all exert excellent barrier effects on liquids or gases. In the high-barrier layer, they can also form a stable and better coordination effect with polyvinyl alcohol, polyamide, and ethylene-vinyl alcohol copolymer, thereby making the high-barrier layer as a whole exhibit relatively excellent and stable barrier properties.

[0033] In a second aspect, the present application provides a method for preparing an environmentally friendly ultra-high barrier packaging paper, which adopts the following technical solution:

[0034] A method for preparing environmentally friendly ultra-high barrier packaging paper comprises the following steps:

[0035] (1) preparing a raw material comprising polyvinyl alcohol, polyamide, ethylene-vinyl alcohol copolymer, barrier filler, and modified mixed fiber;

[0036] (2) uniformly mixing the polyvinyl alcohol, polyamide, ethylene-vinyl alcohol copolymer, barrier filler and modified mixed fiber in step (1), coating the base paper layer on both sides, and drying to obtain a high barrier layer;

[0037] (3) A metal layer is formed on the high barrier layer by vacuum evaporation, and finally a paint is applied on the metal layer to form a coating, thereby obtaining an environmentally friendly ultra-high barrier packaging paper.

[0038] By adopting the above technical solution, the above preparation method is simple to operate and is convenient for large-scale industrial production; and when the modified mixed fiber is used, it only needs to be mixed with other raw materials in the high-barrier layer to be able to exert a stable effect in the future, which makes the application more convenient and can obtain high-quality environmentally friendly ultra-high barrier packaging paper.

[0039] In summary, this application has the following beneficial effects:

[0040] 1. This application modifies fiber raw materials composed of silk fibers and bamboo fibers, and applies the resulting modified mixed fibers to the high-barrier layer. The modified mixed fibers are entangled and bonded with the fiber structure at the pores of the base paper layer. When the high-barrier layer expands and contracts due to changes in ambient temperature, the fibers exert excellent mutual pulling and strain adjustment effects, thereby maintaining excellent stability in the bonding strength between the high-barrier layer and the base paper layer.

[0041] 2. This application blends polyester fiber with modified mixed fiber and then applies it to the high-barrier layer. While complementing each other, it can better cope with the changes in the fiber structure of the base layer. The blended structure of the two has strong anti-destructive properties, and thus is more excellent in maintaining the stability of the bonding strength between the high-barrier layer and the base paper layer in a temperature-changing environment.

[0042] 3. This application adds and uses a functional additive composed of isocyanate and porous ceramic powder. The partially modified mixed fiber is penetrated into the pores of the porous ceramic powder with the help of isocyanate, and then the porous ceramic powder is used as an anchor point in the high-barrier layer. In this way, the bonding stability between the high-barrier layer and the base paper layer can be greatly improved, and the ability to cope with changes in ambient temperature is stronger. DETAILED DESCRIPTION

[0043] The present application is further described in detail below with reference to the embodiments.

[0044] Unless otherwise specified, the raw materials used in the preparation examples and embodiments of this application are commercially available:

[0045] Polyvinyl alcohol was purchased from Inner Mongolia Shuangxin Polyvinyl Alcohol Aqueous Solution, model 2488;

[0046] Polyamide was purchased from Xinyuhong cross-linked polyamide aqueous solution, model number JPH 26063-63-8;

[0047] Ethylene-vinyl alcohol copolymer was purchased from Hongshi HS-330 copolymer emulsion;

[0048] Hyaluronic acid chitosan was purchased from Hubei Chushuo Biotechnology Co., Ltd. with an average molecular weight of 3000;

[0049] The silane coupling agent is KH560 type silane coupling agent;

[0050] The isocyanate is cyclopentyl isocyanate, CAS number 4747-71-1;

[0051] The porous ceramic powder was purchased from Hangzhou Jikang New Materials Co., Ltd. The silicon carbide ceramic powder model is WS05.

[0052] Preparation examples of raw materials and / or intermediates

[0053] Preparation Example 1

[0054] A modified mixed fiber is prepared by the following steps:

[0055] S1. Mixing hyaluronic acid chitosan with saturated sodium bicarbonate solution in a volume ratio of 1:1.3 to obtain a treatment solution, then immersing fiber raw materials in the treatment solution at a ratio of 1 g:600 ml at 55° C. for 60 min, and finally taking out and drying to obtain a pretreated fiber raw material;

[0056] S2. The pretreated fiber raw material is treated with potassium permanganate solution at a temperature of 60°C for 10 minutes, and then mixed with acrylic acid and sulfuric acid for reaction at a temperature of 50°C for 3.5 hours. After boiling, the grafted product is filtered and dried, and then surface treated with a silane coupling agent and dried to obtain a modified mixed fiber.

[0057] Note: In the above steps, the fiber raw materials used are composed of silk fiber and bamboo fiber in a weight ratio of 0.5:1; the concentration of potassium permanganate solution is 0.055 mol / L, the reaction concentration of acrylic acid is 4 mol / L, and the reaction concentration of sulfuric acid is 0.55 mol / L.

[0058] Preparation Example 2

[0059] A modified mixed fiber is different from Preparation Example 1 in that the fiber raw materials are composed of silk fiber and bamboo fiber in a weight ratio of 0.2:1.

[0060] Preparation Example 3

[0061] A modified mixed fiber is different from Preparation Example 1 in that the fiber raw materials are composed of silk fiber and bamboo fiber in a weight ratio of 0.6:1.

[0062] Preparation Example 4

[0063] A modified mixed fiber is different from Preparation Example 1 in that the fiber raw materials are composed of silk fiber and bamboo fiber in a weight ratio of 0.4:1.

[0064] Preparation Example 5

[0065] A modified mixed fiber is different from Preparation Example 1 in that the concentration of the potassium permanganate solution is 0.05 mol / L, the reaction concentration of acrylic acid is 3.5 mol / L, and the reaction concentration of sulfuric acid is 0.5 mol / L.

[0066] Preparation Example 6

[0067] A modified mixed fiber is different from Preparation Example 1 in that the concentration of the potassium permanganate solution is 0.06 mol / L, the reaction concentration of acrylic acid is 4.5 mol / L, and the reaction concentration of sulfuric acid is 0.6 mol / L.

[0068] Preparation Example 7

[0069] A modified mixed fiber is different from Preparation Example 1 in that the fiber raw material does not contain silk fiber.

[0070] Preparation Example 8

[0071] A modified mixed fiber is different from Preparation Example 1 in that the fiber raw material does not contain bamboo fiber.

[0072] Example

[0073] Example 1

[0074] An environmentally friendly ultra-high barrier packaging paper comprises a base paper layer, high-barrier layers are provided on both sides of the base paper layer, a metal layer is provided on the outer side of the high-barrier layer away from the base paper layer, and a coating is provided on the outer side of the metal layer away from the high-barrier layer. The raw materials used to prepare the high-barrier layer and their corresponding weights are shown in Table 1. The preparation method of the environmentally friendly ultra-high barrier packaging paper comprises the following steps:

[0075] (1) preparing a raw material comprising polyvinyl alcohol, polyamide, ethylene-vinyl alcohol copolymer, barrier filler, and modified mixed fiber;

[0076] (2) After the polyvinyl alcohol, polyamide, ethylene-vinyl alcohol copolymer, barrier filler and modified mixed fiber in step (1) are evenly mixed, double-sided coating is performed on the surface of the 0.1 mm thick base paper layer, and the coating amount is 20 g / m 2 , after drying, a high barrier layer is obtained;

[0077] (3) Vacuum evaporation is used to form a metal layer with a thickness of 50nm on the high barrier layer, and finally paint is applied on the metal layer to form a coating. The paint coating amount is 50g / m 2 , and then obtain environmentally friendly ultra-high barrier packaging paper.

[0078] Note: The above-mentioned raw material layer is coated paper, the metal layer is aluminum, and the paint is Huigu Chemical DCW312 water-based polyurethane coating; the barrier filler is a composition of clay, silica and mica in a weight ratio of 3:1:2, and its particle size is 10 μm; the modified mixed fiber is obtained in Preparation Example 1.

[0079] Example 2-3

[0080] An environmentally friendly ultra-high barrier packaging paper, which is different from Example 1 in that the raw materials used to prepare the high barrier layer and their corresponding weights are shown in Table 1.

[0081] Table 1 Raw materials used in the preparation of high barrier layers in Examples 1-3 and their weight parts (kg / part)

[0082]

[0083]

[0084] Example 4

[0085] An environmentally friendly ultra-high barrier packaging paper, which is different from Example 1 in that the modified mixed fiber is obtained in Preparation Example 2.

[0086] Example 5

[0087] An environmentally friendly ultra-high barrier packaging paper, which is different from Example 1 in that the modified mixed fiber is obtained in Preparation Example 3.

[0088] Example 6

[0089] An environmentally friendly ultra-high barrier packaging paper, which is different from Example 1 in that the modified mixed fiber is obtained in Preparation Example 4.

[0090] Example 7

[0091] An environmentally friendly ultra-high barrier packaging paper, which is different from Example 1 in that the modified mixed fiber is obtained in Preparation Example 5.

[0092] Example 8

[0093] An environmentally friendly ultra-high barrier packaging paper, which is different from Example 1 in that the modified mixed fiber is obtained in Preparation Example 6.

[0094] Example 9

[0095] An environmentally friendly ultra-high barrier packaging paper is different from Example 1 in that the modified mixed fiber is blended with polyester fiber before use, and the blending weight ratio of the modified mixed fiber and the polyester fiber is 3.5:1.

[0096] Example 10

[0097] An environmentally friendly ultra-high barrier wrapping paper, which differs from Example 9 in that the blending weight ratio of the modified mixed fiber and the polyester fiber is 2:1.

[0098] Example 11

[0099] An environmentally friendly ultra-high barrier wrapping paper, which differs from Example 9 in that the blending weight ratio of the modified mixed fiber and the polyester fiber is 5:1.

[0100] Example 12

[0101] An environmentally friendly ultra-high barrier packaging paper differs from Example 1 in that 5 parts by weight of a functional additive are also added to the raw materials of the high barrier layer. The functional additive is composed of isocyanate and porous ceramic powder in a weight ratio of 1:2, and the functional additive is mixed with other raw materials of the high barrier layer when used.

[0102] Example 13

[0103] An environmentally friendly ultra-high barrier packaging paper, which differs from Example 12 in that the functional additive consists of isocyanate and porous ceramic powder in a weight ratio of 1:1.8.

[0104] Example 14

[0105] An environmentally friendly ultra-high barrier packaging paper, which differs from Example 12 in that the functional additive consists of isocyanate and porous ceramic powder in a weight ratio of 1:2.4.

[0106] Example 15

[0107] An environmentally friendly ultra-high barrier packaging paper, which differs from Example 12 in that the functional additive consists of isocyanate and porous ceramic powder in a weight ratio of 1:2.1.

[0108] Example 16

[0109] An environmentally friendly ultra-high barrier packaging paper, which is different from Example 12 in that the functional additive is added in an amount of 3 parts by weight.

[0110] Example 17

[0111] An environmentally friendly ultra-high barrier packaging paper, which is different from Example 12 in that the functional additive is added in an amount of 7 parts by weight.

[0112] Example 18

[0113] An environmentally friendly ultra-high barrier packaging paper, which differs from Example 12 in that the functional additive does not contain isocyanate.

[0114] Example 19

[0115] An environmentally friendly ultra-high barrier packaging paper, which differs from Example 12 in that the functional additive does not contain porous ceramic powder.

[0116] Comparative Example

[0117] Comparative Example 1

[0118] An environmentally friendly ultra-high barrier packaging paper, which is different from Example 1 in that the modified mixed fiber is obtained in Preparation Example 7.

[0119] Comparative Example 2

[0120] An environmentally friendly ultra-high barrier packaging paper, which is different from Example 1 in that the modified mixed fiber is obtained in Preparation Example 8.

[0121] Comparative Example 3

[0122] An environmentally friendly ultra-high barrier packaging paper, which differs from Example 1 in that the high barrier layer does not contain modified mixed fibers.

[0123] Comparative Example 4

[0124] An environmentally friendly ultra-high barrier wrapping paper differs from Example 1 in that the modified mixed fiber is replaced by silk fiber and bamboo fiber raw materials in a corresponding weight ratio.

[0125] Performance test samples: The environmentally friendly ultra-high barrier packaging papers obtained in Examples 1-19 were used as test samples 1-19, and the environmentally friendly ultra-high barrier packaging papers obtained in Comparative Examples 1-4 were used as control samples 1-4.

[0126] Test method: (1) Air permeability test: Use a permeability tester to test using the differential pressure method. Place the sample to be tested between the upper and lower test chambers and fix them. The upper chamber is a high-pressure chamber for storing the test gas, and the lower chamber is a low-pressure chamber for storing the permeated gas. At a pressure of 1.24 kPa, record the time required for 100 ml of test gas to pass through the sample to be tested (100 mm x 100 mm). This is recorded as the air permeability (ml / min).

[0127] (2) Water permeability test: perform water permeability test according to the requirements of GB / T22897-2008 “Determination of water permeability of paper and paperboard” and record the penetration time;

[0128] (3) Adhesion strength test between high barrier layer and base paper layer: according to the requirements of GB5210-85 “Determination of adhesion of coatings”, the force required to break the high barrier layer and base paper layer is measured by the pull-off method;

[0129] (4) The test samples 1-19 and the control samples 1-4 were subjected to the above-mentioned air permeability test, water permeability test and adhesion strength test between the high barrier layer and the base paper layer, three times for each sample, and the average value corresponding to each sample was recorded as the initial value; then the test samples 1-19 and the control samples 1-4 were placed in a temperature alternating test box, with the initial temperature being 25°C, firstly heated to 55°C at 2°C / min, then cooled to 5°C at 1°C / min, and finally heated to 25°C at 1.5°C / min, which was recorded as one cycle. After completing 5 cycles, the above-mentioned air permeability test, water permeability test and adhesion strength test between the high barrier layer and the base paper layer were performed, three times for each sample, and the average value corresponding to each sample was recorded as the experimental value; the air permeability loss rate, water permeability loss rate and adhesion strength loss rate were calculated, and the loss rate = (initial value - experimental value) / absolute value of the initial value, which are recorded in Table 2 below.

[0130] Table 2 Test results of test samples 1-19 and control samples 1-4

[0131]

[0132]

[0133] From Examples 1-3 and Comparative Example 3 in combination with Table 2, it can be seen that by modifying the fiber raw materials composed of silk fibers and bamboo fibers and applying the obtained modified mixed fibers to the high-barrier layer, the bonding between the high-barrier layer and the base paper layer can still maintain relatively excellent stability when affected by drastic external temperature changes. Compared with the case where the modified mixed fibers are not used, the air permeability loss rate, water permeability loss rate and bonding strength loss rate obtained in the test are relatively low. From Comparative Example 4 in combination with Table 2, it can be seen that if the silk fibers and bamboo fibers are not modified and are directly applied, although the air permeability loss rate, water permeability loss rate and bonding strength loss rate measured in the test can be reduced, the effect is limited and far less than the corresponding excellent effect brought about by the application of the modified mixed fibers.

[0134] Combining Examples 1 and 4-6 with Table 2, it can be seen that the modified mixed fibers obtained by modifying the fiber raw materials with a weight ratio of (0.2-0.6):1 of silk fiber and bamboo fiber can all play an excellent stabilizing role, so that the bond between the high-barrier layer and the base paper layer can maintain a relatively stable bond when affected by drastic external temperature changes. Among them, when the weight ratio of silk fiber to bamboo fiber is 0.5:1, the overall effect is relatively excellent. Combining Comparative Examples 1-2 with Table 2, it can be seen that the effect of mixing silk fiber or bamboo fiber after modification and application in the high-barrier layer cannot be achieved, indicating that the cooperation between the two plays an important role in building a stable skeleton and bridge between the high-barrier layer and the base paper layer.

[0135] From Example 1 and Examples 9-11 and Table 2, it can be seen that by blending the modified mixed fiber with polyester fiber before use and then applying it to the high-barrier layer, the high-barrier layer and the base paper layer can exhibit stronger resistance to damage when the ambient temperature changes, thereby maintaining better bonding strength stability. The air permeability loss rate, water permeability loss rate, and bonding strength loss rate obtained in the test are further reduced.

[0136] Combining Example 1 and Examples 12-17 with Table 2, it can be seen that adding a functional additive composed of isocyanate and porous ceramic powder in a weight ratio of 1: (1.8-2.4) to the raw materials of the high barrier layer can further improve the bonding stability between the high barrier layer and the base paper layer in a temperature-varying environment, and when the weight ratio of isocyanate and porous ceramic powder is 1: 2, the corresponding effect brought by the application of the functional additive is better. Combining Examples 18-19 with Table 2, it can be seen that if isocyanate or porous ceramic powder is added alone, the improvement effect is limited, and the sum of the improvement effects brought by the use of the two alone is far less than the improvement effect brought by the use of the two as functional additives. It can be seen that isocyanate and porous ceramic powder can play an excellent composite synergistic role in the high barrier layer, thereby significantly reducing the measured air permeability loss rate, water permeability loss rate and bonding strength loss rate.

[0137] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. An environmentally friendly ultra-high barrier packaging paper, characterized in that: The invention comprises a base paper layer, a high barrier layer is provided on both sides of the base paper layer, a metal layer is provided on the outer side of the high barrier layer away from the base paper layer, and a coating is provided on the outer side of the metal layer away from the high barrier layer. The high barrier layer is made of the following raw materials in parts by weight: 40-50 parts of polyvinyl alcohol; Polyamide 15-25 parts; 10-25 parts of ethylene-vinyl alcohol copolymer; 4-8 parts of barrier filler; 5-9 parts of modified mixed fiber; The modified hybrid fiber is prepared by the following steps: S1. Hyaluronic acid chitosan and saturated sodium bicarbonate solution were mixed in a volume ratio of 1:1.3 to obtain a treatment solution, and then a fiber raw material was immersed in the treatment solution at a ratio of 1 g:600 ml at 55° C. for 60 minutes, and finally taken out and dried to obtain a pretreated fiber raw material; S2. The pretreated fiber raw material is treated with potassium permanganate solution, and then mixed with acrylic acid and sulfuric acid for reaction at a reaction temperature of 50° C. for a reaction time of 3.5 hours. After boiling, the obtained grafted product is filtered and dried. The surface of the obtained grafted product is then treated with a silane coupling agent and then dried to obtain a modified mixed fiber. The fiber raw material is composed of silk fiber and bamboo fiber in a weight ratio of (0.2-0.6):1; In step S2, the concentration of the potassium permanganate solution is 0.05-0.06 mol / L, the reaction concentration of acrylic acid is 3.5-4.5 mol / L, and the reaction concentration of sulfuric acid is 0.5-0.6 mol / L.

2. The environmentally friendly ultra-high barrier packaging paper according to claim 1, characterized in that: The fiber raw material consists of silk fiber and bamboo fiber in a weight ratio of 0.5:

1.

3. The environmentally friendly ultra-high barrier packaging paper according to claim 1, characterized in that: The modified mixed fiber is blended with polyester fiber before use, and the blending weight ratio of the modified mixed fiber to the polyester fiber is (2-5):

1.

4. The environmentally friendly ultra-high barrier packaging paper according to claim 3, characterized in that: The blending weight ratio of the modified mixed fiber and the polyester fiber is 3.5:

1.

5. The environmentally friendly ultra-high barrier packaging paper according to claim 1, characterized in that: The raw materials of the high barrier layer are further added with 3-7 parts by weight of a functional additive, which consists of isocyanate and porous ceramic powder, and the weight ratio of isocyanate to porous ceramic powder is 1:(1.8-2.4).

6. The environmentally friendly ultra-high barrier packaging paper according to claim 5, characterized in that: The weight ratio of the isocyanate to the porous ceramic powder is 1:

2.

7. The environmentally friendly ultra-high barrier packaging paper according to claim 1, characterized in that: The barrier filler is one or a combination of zeolite, clay, silica and mica.

8. The method for preparing the environmentally friendly ultra-high barrier packaging paper according to claim 1, characterized in that: The following steps are involved: (1) preparing a raw material comprising polyvinyl alcohol, polyamide, ethylene-vinyl alcohol copolymer, barrier filler, and modified mixed fiber; (2) After uniformly mixing the polyvinyl alcohol, polyamide, ethylene-vinyl alcohol copolymer, barrier filler and modified mixed fiber in step (1), double-sided coating is performed on the surface of the base paper layer, and a high barrier layer is obtained after drying; (3) A metal layer is formed on the high barrier layer by vacuum evaporation, and finally a paint is applied on the metal layer to form a coating, thereby obtaining an environmentally friendly ultra-high barrier packaging paper.

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