A barrier layer composition, its preparation method and application

Abstract

The application belongs to the field of barrier layer compositions, and specifically discloses a barrier layer composition, a preparation method and application thereof. In the barrier layer composition, the nanocrystalline cellulose, the montmorillonite, the ionic liquid and the silane coupling agent can cooperate with each other and synergistically improve the oxygen and water vapor barrier properties of the barrier layer.

Description

Technical Field

[0001] This invention belongs to the field of barrier layer compositions, specifically relating to a barrier layer composition, its preparation method, and its application. Background Technology

[0002] Food and medicine are susceptible to environmental factors such as air, moisture, grease, and dust. Proper storage and packaging can delay spoilage or damage. Therefore, packaging materials for food and medicine must have high barrier properties to reduce or prevent the penetration of moisture, grease, water vapor, oxygen, and other substances into the packaging.

[0003] Plastics, such as polyethylene and polypropylene, are commonly used as the main raw materials for this type of packaging material. These materials offer excellent barrier properties against gas penetration, oil, and water. However, many of these plastics degrade extremely slowly, or are even non-biodegradable, making them difficult to recycle and leading to environmental pollution from discarded packaging materials. To reduce environmental pressure, barrier layers with barrier functions can be prepared on the base paper to form barrier-functional composites, meeting the packaging needs of food, pharmaceuticals, and other products. However, because base paper is a plant fiber with multiple hydroxyl groups, capillary action, and high porosity, existing barrier layer coatings offer relatively poor barrier effects against oxygen and water vapor. Summary of the Invention

[0004] In view of the problems of poor barrier layer coatings in the prior art, the present invention will provide a barrier layer composition, its preparation method and application.

[0005] To achieve the above objectives, the following technical solutions are specifically included:

[0006] A barrier layer composition comprising the following components in weight percentages:

[0007] Resin 30-60%, nanocrystalline cellulose 5-15%, montmorillonite 1-5%, ionic liquid 0.05-1.5%, silane coupling agent 1-5%, balance solvent.

[0008] In this invention, the barrier layer composition utilizes nanocrystalline cellulose and montmorillonite to synergistically extend the diffusion path of liquid and gas molecules, thereby improving the barrier layer composition's ability to block water and gas. Simultaneously, because nanocrystalline cellulose and montmorillonite have poor compatibility with resins, they are further modified hydrophobically using ionic liquids and silane coupling agents, which improves the compatibility of nanocrystalline cellulose and montmorillonite with resins, thereby enhancing the barrier layer composition's ability to block liquids and gases, particularly its ability to block oxygen and water vapor.

[0009] Preferably, the resin comprises at least one of polyvinyl alcohol (PVA), methyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, polypropylene carbonate, polycaprolactone, polybutylene adipate terephthalate, and polybutylene succinate.

[0010] Preferably, the resin is polyvinyl alcohol and methyl methacrylate, and the mass ratio of polyvinyl alcohol to polybutylene adipate is (1.5-7):1.

[0011] The resin not only has good film-forming properties, but also has good barrier properties against gases, water vapor, and grease. In particular, when the above-mentioned types of resin are used, the barrier layer composition can further have a good oxygen and water vapor barrier effect.

[0012] Preferably, the mass ratio of the nanocrystalline cellulose to the resin is (2-8):1.

[0013] Nanocrystalline cellulose binds to resin through hydrogen bonds, increasing crystallinity, reducing the hydrophilicity of the coating made from the composition, and improving the barrier properties of the coating against water vapor and oxygen.

[0014] Preferably, the ionic liquid comprises at least one of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-ethyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium octylsulfonate, 1-methylimidazolium tetrafluoroborate, and N-methylimidazolium bis(trifluoromethanesulfonyl)imide.

[0015] Ionic liquids can activate and hydrophobically modify nanocrystalline cellulose and montmorillonite, improve the compounding effect of nanocrystalline cellulose, montmorillonite and resin, and thus improve the ability of the coating made by the barrier layer composition to block oxygen and water vapor.

[0016] Preferably, the silane coupling agent includes at least one of 3-aminopropyltriethoxysilane, trimethoxymethylsilane, and vinyltrimethoxysilane.

[0017] Silane coupling agents are amphiphilic and can promote the bonding of nanocrystalline cellulose, montmorillonite and resin after activation by ionic liquid, improve the compounding effect between components, and thus improve the ability of the coating made by the barrier layer composition to block oxygen and water vapor.

[0018] Preferably, the montmorillonite has a layered structure and the average size of the montmorillonite is 10-500 nm.

[0019] Preferably, the mass ratio of montmorillonite to nanocrystalline cellulose is (1.5-11.5):1.

[0020] More preferably, the mass ratio of montmorillonite to nanocrystalline cellulose is (3-5):1.

[0021] Montmorillonite has a layered structure. When liquid and gas molecules enter, the layered two-dimensional structure can extend the molecular diffusion path, thereby improving the ability of the coating made from the barrier layer composition to block liquids and gases. In addition, the smaller particle size of nano-sized montmorillonite increases the density of the coating to a greater extent, which can further improve the ability of the coating made from the barrier layer composition to block oxygen and water vapor.

[0022] Preferably, the solvent includes at least one of water and alcohol solvents.

[0023] Preferably, when the solvent is water and an alcohol solvent, the water content is 10-50 wt.% and the alcohol solvent content is 5-10%.

[0024] Preferably, the alcohol solvent includes at least one of ethanol, methanol, and glycerol.

[0025] When the resin is polyvinyl alcohol, water can be chosen as the solvent, as the resin can dissolve in hot water. This reduces the organic solvent content of the overall barrier layer composition, making it more environmentally friendly. When the resin is not water-soluble, alcohol solvents can be used for dissolution and dispersion.

[0026] The present invention also provides a method for preparing the barrier layer composition, comprising the following steps:

[0027] (1) Nanocrystalline cellulose, montmorillonite, ionic liquid and part of solvent are mixed and reacted to obtain the first mixture;

[0028] (2) Mix the resin, silane coupling agent and the remaining solvent evenly to obtain a second mixture;

[0029] (3) Mix the second mixture and the first mixture, homogenize them, and obtain the barrier layer composition.

[0030] Preferably, the temperature of the reaction in step (1) is 50-90°C and the reaction time is 1-6 hours.

[0031] Preferably, the mixing temperature in step (2) is 35-90°C, and the homogenization stirring rate is 500-1500 rpm.

[0032] Preferably, the mixing temperature in step (3) is 35-80°C.

[0033] Increasing the temperature appropriately during mixing can promote better mixing between the components.

[0034] The present invention also provides an application of the barrier layer composition in food and pharmaceutical packaging paper. The barrier layer composition can be directly coated onto food and pharmaceutical packaging paper using conventional coating methods. After drying and curing, a barrier layer is formed on the food and pharmaceutical packaging paper. This barrier layer has excellent properties of blocking oxygen and water vapor, as well as conventional oil and water resistance, and is environmentally friendly, meeting the application requirements of food and pharmaceutical packaging paper.

[0035] Compared with the prior art, the present invention has the following beneficial effects: the nanocrystalline cellulose, montmorillonite, ionic liquid and silane coupling agent in the barrier layer combination of the present invention can cooperate with each other to synergistically improve the barrier layer's performance in blocking oxygen and water vapor. Detailed Implementation

[0036] To better illustrate the purpose, technical solution, and advantages of this invention, specific embodiments will be used to further explain the invention below. Unless otherwise specified, the test methods used in the embodiments and / or comparative examples are conventional methods; the materials and reagents used, unless otherwise specified, are commercially available.

[0037] Examples 1-16 and Comparative Examples 1-4

[0038] Examples 1-16 and Comparative Examples 1-4 describe a method for preparing the barrier layer composition, comprising the following steps:

[0039] (1) Mix nanocrystalline cellulose, montmorillonite, ionic liquid and some water according to the proportions in Tables 1 and 2, and react at 70°C for 5 hours to obtain the first mixture;

[0040] (2) Dissolve polyvinyl alcohol in a portion of water at 90°C to obtain a polyvinyl alcohol aqueous solution; then selectively add other resins, or first dissolve other alcohol-soluble resins in ethanol to obtain a resin ethanol solution; mix the polyvinyl alcohol aqueous solution and the selectively added resins or resin ethanol solution at room temperature, then add a silane coupling agent and mix evenly to obtain a second mixture;

[0041] (3) The second mixture and the first mixture are mixed and homogenized at 40°C and 1000 rpm for 1 hour to obtain the barrier layer composition;

[0042] For the raw material descriptions in the table below:

[0043] The molecular weight of polyvinyl alcohol is 4000; the montmorillonite is nanoscale layered montmorillonite with a size range of less than 500 nm; ionic liquid 1 is 1-butyl-3-methylimidazolium hexafluorophosphate, ionic liquid 2 is 1-ethyl-3-methylimidazolium acetate, and ionic liquid 3 is 1-butyl-3-methylimidazolium octylsulfonate; silane coupling agent 1 is 3-aminopropyltriethoxysilane, silane coupling agent 2 is trimethoxymethylsilane, and silane coupling agent 3 is vinyltrimethoxysilane.

[0044] Table 1

[0045]

[0046]

[0047] Table 2

[0048]

[0049] The barrier layers prepared in the above embodiments and comparative examples were combined and coated onto the base paper, with a coating amount of 20 g / m². 2 After drying, a barrier layer is formed on the base paper. The base paper can be parchment, metallized paper, food-grade cardboard, etc., but to better highlight the barrier performance, conventional food-grade cardboard is selected. The oxygen permeability of the barrier layer is tested according to GB / T1038-2000 standard, with units of cm³ / m. 2 •d·MPa; Water vapor permeability at 23℃ and 50% relative humidity, tested according to GB / T21529-2008 standard, unit is g / (m³). 2 • 24h), the test results are shown in Table 3.

[0050] According to the TAPPI 559cm-02 "Grease resistance test for paper and paperboard" test method, the oil resistance of the barrier layer is divided into 1-12 grades, with grade 1 being the worst and grade 12 being the best. The oil resistance grade of the barrier layers prepared by the barrier layer compositions in Examples 1-16 above is 12. At the same time, the water contact angle of the barrier layer was tested using a contact angle measuring instrument. The water contact angle of the barrier layers prepared by the barrier layer compositions in Examples 1-16 above is greater than 150°.

[0051] Table 3

[0052] Group / Project <![CDATA[Oxygen permeability, cm3 / m 2 ·d·MPa]]> <![CDATA[Water vapor permeability, g / (m 2 ·24h)]]> Food-grade cardboard 900 950 Example 1 157 274 Example 2 143 214 Example 3 104 167 Example 4 126 198 Example 5 302 412 Example 6 121 266 Example 7 186 305 Example 8 226 365 Example 9 278 403 Example 10 128 215 Example 11 169 275 Example 12 211 343 Example 13 175 270 Example 14 145 258 Example 15 259 312 Example 16 205 296 Comparative Example 1 725 868 Comparative Example 2 615 695 Comparative Example 3 586 801 Comparative Example 4 501 587

[0053] As can be seen from the above embodiments, the barrier layer composition of the present invention can make the oxygen permeability of the barrier layer less than 310 cm3 / m. 2 Below ·d·MPa, water vapor permeability is less than 420g / (m³). 2It has excellent ability to block oxygen and water vapor (24h).

[0054] As can be seen from Example 1 and Comparative Examples 1-4, the nanocrystalline cellulose, montmorillonite, ionic liquid, and silane coupling agent in the system of the present invention can work together to synergistically improve the performance of the barrier layer in blocking oxygen and water vapor.

[0055] As can be seen from Examples 1-4, the combined use of polyvinyl alcohol and methyl methacrylate can further improve the barrier layer's ability to block oxygen and water vapor.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A barrier layer composition characterized in that, consists of the following components by mass percentage: Resin 30-60%, nanocrystalline cellulose 5-15%, montmorillonite 1-5%, ionic liquid 0.05-1.5%, silane coupling agent 1-5%, the balance solvent; the resin is polyvinyl alcohol and methyl methacrylate, the mass ratio of the polyvinyl alcohol and methyl methacrylate is 7:1, 3:1 or 5:3; the ionic liquid includes at least one of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide, 1-ethyl-3-methylimidazole acetate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium octanesulfonate, 1-methylimidazole tetrafluoroborate, N-methylimidazolium bis(trifluoromethanesulfonyl) imide; the silane coupling agent includes at least one of 3-aminopropyltriethoxysilane, trimethoxymethylsilane, vinyltrimethoxysilane; The preparation method of the barrier layer composition comprises the following steps: (1) nanocrystalline cellulose, montmorillonite, ionic liquid and part of the solvent are mixed and reacted to obtain a first mixture; the reaction temperature is 50-90℃; (2) the resin, the silane coupling agent and the remaining part of the solvent are mixed uniformly to obtain a second mixture; (3) the second mixture and the first mixture are mixed and homogenized to obtain the barrier layer composition.

2. The barrier layer composition of claim 1, wherein, The solvent includes water and an alcohol solvent.

3. A process for the preparation of the barrier layer composition according to claim 1 or 2, characterized in that Comprises the following steps: (1) nanocrystalline cellulose, montmorillonite, ionic liquid and part of the solvent are mixed and reacted to obtain a first mixture, and the reaction temperature is 50-90℃; (2) the resin, the silane coupling agent and the remaining part of the solvent are mixed uniformly to obtain a second mixture; (3) the second mixture and the first mixture are mixed and homogenized to obtain the barrier layer composition.

4. The method of claim 3, wherein the barrier layer composition is prepared by a method comprising: The reaction time in step (1) is 1-6h.

5. The barrier layer composition of claim 1 or 2 is applied to paper for food and drug packaging.

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