Super-strong barrier packaging paper and preparation method thereof

Abstract

The invention provides super-strong barrier packaging paper and a preparation method thereof, relates to the field of high-barrier packaging paper, and aims to solve the problems that the barrier property of a traditional packaging material is reduced and the mechanical property is insufficient in a high-humidity environment. The packaging paper is composed of a coating barrier layer, a transparent film layer and a body paper base layer, and is prepared through a special process, so that the transmittance of oxygen and water vapor is remarkably reduced, and the shelf life of packaged contents is effectively prolonged. The preparation method comprises the following steps: mixing wood pulp fibers with a citric acid hydration solution, adding materials such as cationic starch to form fiber slurry, and drying to obtain the raw paper base layer; mixing and extruding acrylonitrile copolymer and other materials to form a transparent film layer; materials such as lignin and a citric acid hydration solution are mixed to form cross-linked slurry, the cross-linked slurry is mixed with a polymer solution to obtain a cross-linked coating, the raw paper base layer is coated with the cross-linked coating, the cross-linked coating is dried and then compounded with the transparent film layer, and the packaging paper has excellent barrier performance and mechanical performance and is particularly suitable for being used in areas with large temperature and humidity changes.

Description

Technical Field

[0001] The invention relates to the field of high barrier packaging paper, in particular to super barrier packaging paper and a preparation method thereof. Background Art

[0002] In the modern packaging industry, high-barrier packaging materials are valued for their ability to significantly extend the shelf life of food, medicine and other products. These materials can prevent the penetration of oxygen and water vapor, thereby protecting the contents from the external environment and maintaining their freshness and stability. As consumers' requirements for product quality increase, the development of new high-barrier packaging materials has become a research hotspot.

[0003] Traditional packaging materials, including plastics and paper, plastic, and aluminum composites, have certain barrier properties, but they have significant shortcomings in terms of sustainability and environmental impact. The production and use of these materials consume a large amount of non-renewable resources and cause serious pollution to the environment after they are discarded. In addition, in a high humidity environment, the barrier properties of traditional packaging materials drop sharply, and they cannot effectively prevent the penetration of oxygen and water vapor, thus affecting the storage quality of the product. At the same time, traditional packaging materials also have deficiencies in mechanical properties, especially in tensile strength, which limits their application effect when subjected to physical damage and environmental pressure, which to a certain extent restricts their scope of application. Summary of the invention

[0004] In view of the above problems, the present invention provides a super-strong barrier packaging paper and a preparation method thereof.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: a super-strong barrier packaging paper and a preparation method thereof, comprising the following steps:

[0006] S1: Mixing wood pulp fiber and citric acid hydration solution a to form a fiber suspension, uniformly mixing cationic starch a, talcum powder and softener with the fiber suspension to obtain fiber slurry, placing the fiber slurry on a net to form, and using a vacuum pressing roller to press and dehydrate the paper, and finally drying at 100° C. to 110° C. to obtain a base paper;

[0007] S2: uniformly mixing acrylonitrile copolymer a, ethylene glycol a and polybutyl methacrylate a in a certain ratio, heating the mixed material to a molten state in an extruder, and uniformly extruding it through the screw of the extruder to form a continuous molten film, while also heating polyvinylidene chloride a to a molten state, and extruding it into a film through another extruder, and then compounding the two molten materials in a hot pressing laminating machine to obtain a transparent film layer;

[0008] S3: First, the dried lignin, cationic starch b, chitosan and kaolin are mixed with zeolite, and a citric acid hydrate solution b is added, and then stirred at 85°C to 95°C for 1 to 2 hours, and the stirring speed is controlled at 3200 to 6000 rpm to promote the cross-linking reaction between the materials to form a cross-linked slurry; then, polyvinylidene chloride b, acrylonitrile copolymer b, ethylene glycol b and polymethyl methacrylate b are mixed and heated to a molten state to form a uniform polymer solution; the obtained cross-linked slurry is mixed with the polymer solution at 90°C to 100°C, and the stirring is continued for 2 to 3 hours, and the stirring speed is adjusted to 800 to 1200 rpm to obtain a cross-linked coating, and finally the mixed cross-linked coating is ground and refined using a sand mill or a ball mill,

[0009] Finally, a coating barrier layer material is obtained;

[0010] S4: The coating barrier layer material is evenly coated on the base paper by a coating machine, and then dried at 90°C to 100°C. The transparent film layer is then composited with the base paper coated with the coating barrier layer by hot pressing to obtain the final super-strong barrier packaging paper.

[0011] Preferably, the base paper layer is composed of 50% to 70% wood pulp fiber, 10% to 15% citric acid hydrate solution a, 5% to 15% cationic starch a, 5% to 15% talcum powder, and 2% to 8% softener; the transparent film layer is composed of 30% to 50% polyvinylidene chloride a, 20% to 40% acrylonitrile copolymer a, 5% to 15% ethylene glycol, and 10% to 30% polybutyl methacrylate a; the coating barrier layer material is composed of 10% to 20% lignin, 5% to 15% cationic starch b, 5% to 15% chitosan, 10% to 20% zeolite, 10% to 20% kaolin, 5% to 15% citric acid hydrate solution b, 5% to 15% polyvinylidene chloride b, 5% to 15% acrylonitrile copolymer b, 3% to 10% ethylene glycol, and 3% to 10% polybutyl methacrylate b.

[0012] Preferably, the super strong barrier packaging paper comprises a coating barrier layer, a transparent film layer, and a base paper layer; the coating barrier layer has a weight of 1.0 to 3.0 g / m 2 ; The quantitative weight of the transparent film layer after drying is 0.5~2.5g / m 2 .

[0013] The lignin is a natural polymer compound rich in active groups such as phenolic hydroxyl groups and alcoholic hydroxyl groups. The citric acid in the citric acid hydrate solution can undergo an esterification reaction with the phenolic hydroxyl groups and alcoholic hydroxyl groups in the lignin to form ester bonds, thereby achieving cross-linking between lignin molecules; the cationic starch in the coating barrier layer and the base paper layer contains amino groups, which can undergo an amidation reaction with the carboxyl groups in the citric acid to form amide bonds, thereby enhancing cross-linking between molecules; in addition, the amino groups in chitosan can also react with citric acid to enhance cross-linking between molecules. The base paper layer and the coating barrier layer both contain cationic starch. The cationic groups of the cationic starch can form ionic bonds with the fibers in the base paper layer and the lignin in the coating barrier layer, thereby playing a bridging role and enhancing the bonding force between layers.

[0014] Preferably, the monomers of the acrylonitrile copolymer a and the acrylonitrile copolymer b are composed of 20% acrylonitrile, 30% 1,3-butadiene and 50% styrene.

[0015] Preferably, the citric acid hydration solution a and the citric acid hydration solution b are composed of 20% to 40% citric acid, 1% to 3% magnesium chloride and 1% to 3% magnesium sulfate and the balance water.

[0016] Preferably, the softener is hydroxypropylated starch.

[0017] Beneficial Effects

[0018] The present invention provides a super-strong barrier packaging paper and a preparation method thereof, which has the following beneficial effects:

[0019] 1. The ultra-strong barrier packaging paper of the present invention significantly reduces the oxygen and water vapor transmission rate through the unique coating barrier layer and transparent film layer structure design, effectively prolonging the shelf life of the packaged contents, especially in applications under high humidity environments.

[0020] 2. Through the cross-linking reaction of citric acid hydrate solution with lignin, cationic starch and chitosan, a denser network structure is formed, and the cohesion and overall strength of the paper are improved, thereby improving the tensile and tear resistance of the packaging paper, making the packaging more durable and reliable.

[0021] 3. A denser network structure is formed through the cross-linking reaction of citric acid hydrate solution with lignin, cationic starch and chitosan.

[0022] 4. The water vapor transmission rate test of the super-barrier packaging paper at 38°C and 90% RH showed excellent barrier properties, indicating that the packaging paper can adapt to changing environmental conditions and is particularly suitable for use in areas with large changes in temperature and humidity. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] Embodiment 1:

[0025] A method for preparing super-strong barrier packaging paper comprises the following steps:

[0026] S1: 60% of wood pulp fiber and 15% of citric acid hydration solution a are mixed to form a fiber suspension. 10% of cationic starch a, 10% of talcum powder, and 5% of softener are added thereto, and the mixture is uniformly mixed to obtain a fiber slurry. The fiber slurry is formed on a net, and is squeezed and dehydrated using a vacuum press roller. Finally, it is dried at 100°C to 110°C to obtain a base paper substrate.

[0027] S2: 30% acrylonitrile copolymer a, 10% ethylene glycol a and 20% polybutyl methacrylate a are mixed evenly, heated to a molten state and extruded into a film through an extruder. At the same time, 40% polyvinylidene chloride a is also heated to a molten state and extruded into a film through another extruder. The two molten materials are compounded in a hot pressing compounding machine to obtain a transparent film layer.

[0028] S3: First, 20% of dried lignin, 15% of cationic starch b, 10% of chitosan, 10% of kaolin and 10% of zeolite are mixed, and 10% of citric acid hydrate solution is added, and then stirred at 85°C to 95°C for 1 to 2 hours, and the stirring speed is controlled at 3200 to 6000 rpm. Subsequently, 10% of polyvinylidene chloride b, 5% of acrylonitrile copolymer b, 5% of ethylene glycol b and 5% of polymethyl methacrylate b are mixed and heated to a molten state to form a uniform polymer solution. The obtained cross-linked slurry is mixed with the polymer solution at 90°C to 100°C, and stirring is continued for 2 to 3 hours. The stirring speed is adjusted to 800 to 1200 rpm to obtain a cross-linked coating. Finally, the mixed coating is ground and refined using a sand mill to finally obtain a coating barrier layer material.

[0029] S4: The coating barrier layer material is evenly coated on the base paper through a coating machine, and then dried at 90°C to 100°C. The transparent film layer is then composited with the base paper coated with the coating barrier layer by hot pressing to obtain the final super strong barrier packaging paper.

[0030] Embodiment 2:

[0031] A method for preparing super-strong barrier packaging paper comprises the following steps:

[0032] S1: 55% of wood pulp fiber and 12% of citric acid hydrate solution a are mixed to form a fiber suspension. 8% of cationic starch a, 7% of talcum powder, and 5% of softener are added thereto and mixed evenly to obtain a fiber slurry. The fiber slurry is formed on a net and squeezed and dehydrated using a vacuum press roller. Finally, it is dried at 100°C to 110°C to obtain a base paper substrate.

[0033] S2: Mix acrylonitrile copolymer a35%, ethylene glycol a12% and polybutyl methacrylate a23% evenly, heat to a molten state and extrude into a film through an extruder. At the same time, polyvinylidene chloride a30% material is also heated to a molten state and extruded into a film through another extruder. The two molten materials are compounded in a hot pressing compounding machine to obtain a transparent film layer.

[0034] S3: First, 18% of dried lignin, 8% of cationic starch b, 8% of chitosan, 12% of kaolin and 12% of zeolite are mixed, and 10% of citric acid hydrate solution is added, and then stirred at 85°C to 95°C for 1 to 2 hours, and the stirring speed is controlled at 3200 to 6000 rpm. Subsequently, 10% of polyvinylidene chloride b, 10% of acrylonitrile copolymer b, 6% of ethylene glycol b and 6% of polymethyl methacrylate b are mixed and heated to a molten state to form a uniform polymer solution. The obtained cross-linked slurry is mixed with the polymer solution at 90°C to 100°C, and stirring is continued for 2 to 3 hours. The stirring speed is adjusted to 800 to 1200 rpm to obtain a cross-linked coating. Finally, the mixed coating is ground and refined using a ball mill to finally obtain a coating barrier layer material.

[0035] S4: The coating barrier layer material is evenly coated on the base paper by a coating machine, and then dried at 90°C to 100°C. The transparent film layer is then composited with the base paper coated with the coating barrier layer by hot pressing to obtain the final super-strong barrier packaging paper.

[0036] Embodiment 3:

[0037] A method for preparing super-strong barrier packaging paper comprises the following steps:

[0038] S1: 70% of wood pulp fiber and 10% of citric acid hydration solution a are mixed to form a fiber suspension. 5% of cationic starch a, 5% of talcum powder, and 3% of softener are added thereto and mixed evenly to obtain a fiber slurry. The fiber slurry is formed on a net and squeezed and dehydrated using a vacuum press roller. Finally, it is dried at 100°C to 110°C to obtain a base paper substrate.

[0039] S2: Evenly mix acrylonitrile copolymer a25%, ethylene glycol a8% and polybutyl methacrylate a27%, heat to a molten state and extrude into a film through an extruder. At the same time, polyvinylidene chloride a35% material is also heated to a molten state and extruded into a film through another extruder. The two molten materials are compounded in a hot pressing compounding machine to obtain a transparent film layer.

[0040] S3: First, 12% of dried lignin, 6% of cationic starch b, 6% of chitosan, 14% of kaolin and 14% of zeolite are mixed, and 8% of citric acid hydrate solution b is added, and then stirred at 85℃~95℃ for 1~2 hours, and the stirring speed is controlled at 3200~6000rpm. Subsequently, 20% of polyvinylidene chloride b, 8% of acrylonitrile copolymer b, 6% of ethylene glycol b and 6b% of polymethyl methacrylate are mixed and heated to a molten state to form a uniform polymer solution. The obtained cross-linked slurry is mixed with the polymer solution at 90℃~100℃, and the stirring is continued for 2~3 hours. The stirring speed is adjusted to 800~1200rpm. Finally, the mixed coating is ground and refined by a sand mill to finally obtain a coating barrier layer material.

[0041] S4: The coating barrier layer material is evenly coated on the base paper by a coating machine, and then dried at 90°C to 100°C. The transparent film layer is then composited with the base paper coated with the coating barrier layer by hot pressing to obtain the final super-strong barrier packaging paper.

[0042] Embodiment 4:

[0043] A method for preparing super-strong barrier packaging paper comprises the following steps:

[0044] S1: 65% of wood pulp fiber and 13% of citric acid hydrate solution a are mixed to form a fiber suspension. 9% of cationic starch a, 8% of talcum powder, and 4% of softener are added thereto and mixed evenly to obtain a fiber slurry. The fiber slurry is formed on a net and squeezed and dehydrated using a vacuum press roller. Finally, it is dried at 100°C to 110°C to obtain a base paper substrate.

[0045] S2: acrylonitrile copolymer a32%, ethylene glycol a9% and polybutyl methacrylate a29% are mixed evenly, heated to a molten state and extruded into a film through an extruder. At the same time, polyvinylidene chloride a33% material is also heated to a molten state and extruded into a film through another extruder. The two molten materials are compounded in a hot pressing compounding machine to obtain a transparent film layer.

[0046] S3: First, 17% of dried lignin, 9% of cationic starch b, 9% of chitosan, 13% of kaolin and 13% of zeolite are mixed, and 9% of citric acid hydrate solution b is added, and then stirred at 85℃~95℃ for 1~2 hours, and the stirring speed is controlled at 3200~6000rpm. Subsequently, polyvinylidene chloride b10%, acrylonitrile copolymer b8%, ethylene glycol b7% and polymethyl methacrylate b7% are mixed and heated to a molten state to form a uniform polymer solution. The obtained cross-linked slurry is mixed with the polymer solution at 90℃~100℃, and the stirring is continued for 2~3 hours. The stirring speed is adjusted to 800~1200rpm. Finally, the mixed coating is ground and refined by a ball mill to finally obtain a coating barrier layer material.

[0047] S4: The coating barrier layer material is evenly coated on the base paper by a coating machine, and then dried at 90°C to 100°C. The transparent film layer is then composited with the base paper coated with the coating barrier layer by hot pressing to obtain the final super-strong barrier packaging paper.

[0048] Embodiment 5:

[0049] A method for preparing super-strong barrier packaging paper comprises the following steps:

[0050] S1: 68% of wood pulp fiber and 14% of citric acid hydrate solution a are mixed to form a fiber suspension. 7% of cationic starch a, 9% of talcum powder, and 6% of softener are added thereto and mixed evenly to obtain a fiber slurry. The fiber slurry is formed on a net and squeezed and dehydrated using a vacuum press roller. Finally, it is dried at 100°C to 110°C to obtain a base paper substrate.

[0051] S2: acrylonitrile copolymer a38%, ethylene glycol a11% and polybutyl methacrylate a26% are mixed evenly, heated to a molten state and extruded into a film through an extruder. At the same time, polyvinylidene chloride a37% material is also heated to a molten state and extruded into a film through another extruder. The two molten materials are compounded in a hot pressing compounding machine to obtain a transparent film layer.

[0052] S3: First, 10% of dried lignin, 15% of cationic starch b, 7% of chitosan, 20% of kaolin and 11% of zeolite are mixed, and 7% of citric acid hydrate solution b is added, and then stirred at 85°C to 95°C for 1 to 2 hours, and the stirring speed is controlled at 3200 to 6000 rpm. Subsequently, 8% of polyvinylidene chloride b, 9% of acrylonitrile copolymer b, 3% of ethylene glycol b and 10% of polymethyl methacrylate b are mixed and heated to a molten state to form a uniform polymer solution. The obtained cross-linked slurry is mixed with the polymer solution at 90°C to 100°C, and stirring is continued for 2 to 3 hours. The stirring speed is adjusted to 800 to 1200 rpm to obtain a cross-linked coating. Finally, the mixed coating is ground and refined using a sand mill to finally obtain a coating barrier layer material.

[0053] S4: The coating barrier layer material is evenly coated on the base paper by a coating machine, and then dried at 90°C to 100°C. The transparent film layer is then composited with the base paper coated with the coating barrier layer by hot pressing to obtain the final super-strong barrier packaging paper.

[0054] Comparative Example 1:

[0055] Comparative Example 1 Except that no cationic starch was added during the preparation of S1 and S2, the remaining raw material ratios, preparation methods, and operating conditions were the same as those of Example 1.

[0056] Comparative Example 2:

[0057] Comparative Example 2 Except that no citric acid hydrate solution was added during the preparation of S1 and S2, the remaining raw material ratios, preparation methods, and operating conditions were the same as those of Example 1.

[0058] The lowercase letters ab after the above material names are used for marking only, and the corresponding materials are essentially the same.

[0059] Performance Test:

[0060] The ultra-strong barrier packaging papers prepared in Examples 1 to 5 and Comparative Examples 1 to 2 were used as test samples to measure tensile strength (MPa), oxygen permeability (cm 3 / m 2 ·d·Pa), water vapor transmission rate (WVTR, g / m 2 / d) test, where the water vapor transmission rate test was conducted at 38°C and 90% RH. The specific results are shown in Table 1:

[0061] Table 1

[0062]

[0063]

[0064] The citric acid hydrate solution undergoes a cross-linking reaction with lignin, cationic starch and chitosan, which enhances the binding force between molecules. This cross-linking effect improves the cohesion and overall strength of the paper, thereby improving the tensile strength. The cationic groups of the cationic starch form ionic bonds with the fibers and lignin, which enhances the binding force between layers and further improves the tensile strength. Through the cross-linking reaction of the citric acid hydrate solution with lignin, cationic starch and chitosan, a denser network structure is formed, which effectively reduces the permeation path of oxygen molecules, thereby reducing the oxygen permeability.

[0065] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing super strong barrier packaging paper, characterized in that: The following steps are involved: S1: Mixing wood pulp fiber and citric acid hydration solution a to form a fiber suspension, uniformly mixing cationic starch a, talcum powder and softener with the fiber suspension to obtain fiber slurry, placing the fiber slurry on a net to form, and using a vacuum pressing roller to press and dehydrate the paper, and then drying at 100° C. to 110° C. to obtain a base paper; S2: uniformly mixing acrylonitrile copolymer a, ethylene glycol a and polybutyl methacrylate a in a certain ratio, heating the mixed material to a molten state in an extruder, and uniformly extruding it through the screw of the extruder to form a continuous molten film, while also heating polyvinylidene chloride a to a molten state, and extruding it into a film through another extruder, and then compounding the two molten materials in a hot pressing laminating machine to obtain a transparent film layer; S3: firstly, the dried lignin, cationic starch b, chitosan and kaolin are mixed with zeolite, and citric acid hydration solution b is added, and then stirred at 85° C. to 95° C. for 1 to 2 hours, and the stirring speed is controlled at 3200 to 6000 rpm to promote the cross-linking reaction between the materials to form a cross-linked slurry; Subsequently, polyvinylidene chloride b, acrylonitrile copolymer b, ethylene glycol b and polymethyl methacrylate b are mixed and heated to a molten state to form a uniform polymer solution; the obtained cross-linked slurry is mixed with the polymer solution at 90° C. to 100° C., and stirring is continued for 2 to 3 hours, and the stirring speed is adjusted to 800 to 1200 rpm to obtain a cross-linked coating, and finally the mixed cross-linked coating is ground and refined using a sand mill or a ball mill to finally obtain a coating barrier layer material; S4: The coating barrier layer material is evenly coated on the base paper by a coating machine, and then dried at 90°C to 100°C. The transparent film layer is then composited with the base paper coated with the coating barrier layer by hot pressing to obtain the final super-strong barrier packaging paper.

2. The method for preparing a super strong barrier packaging paper according to claim 1, characterized in that: The super strong barrier packaging paper comprises a coating barrier layer, a transparent film layer and a base paper layer; the coating barrier layer has a weight of 1.0 to 3.0 g / m after drying. 2 ; The quantitative amount of the transparent film layer after drying is 0.5~2.5g / 2 m。 3. The method for preparing a super strong barrier packaging paper according to claim 1, characterized in that: The base paper substrate is composed of 50% to 70% wood pulp fiber, 10% to 15% citric acid hydrate solution a, 5% to 15% cationic starch a, 5% to 15% talcum powder, and 2% to 8% softener; the transparent film layer is composed of 30% to 50% polyvinylidene chloride a, 20% to 40% acrylonitrile copolymer a, 5% to 15% ethylene glycol, and 10% to 30% polybutyl methacrylate a; the coating barrier layer material is composed of 10% to 20% lignin, 5% to 15% cationic starch b, 5% to 15% chitosan, 10% to 20% zeolite, 10% to 20% kaolin, 5% to 15% citric acid hydrate solution b, 5% to 15% polyvinylidene chloride b, 5% to 15% acrylonitrile copolymer b, 3% to 10% ethylene glycol, and 3% to 10% polybutyl methacrylate b.

4. The method for preparing a super strong barrier packaging paper according to claim 1, characterized in that: The monomers of the acrylonitrile copolymer a and the acrylonitrile copolymer b are both composed of 20% acrylonitrile, 30% 1,3-butadiene and 50% styrene.

5. The method for preparing a super strong barrier packaging paper according to claim 1, characterized in that: The citric acid hydration solution a and the citric acid hydration solution b are both composed of 20% to 40% of citric acid, 1% to 3% of magnesium chloride and 1% to 3% of magnesium sulfate and the balance of water.

6. The method for preparing a super strong barrier packaging paper according to claim 1, characterized in that: The softener is hydroxypropylated starch.

7. A super strong barrier packaging paper, characterized in that: The super-strong barrier packaging paper is prepared by the method for preparing super-strong barrier packaging paper described in claims 1 to 6.

Images