A water- and oil-blocking and anti-sticking food plastic-free packaging paper, its preparation method and application

Abstract

The present invention belongs to the technical field of food packaging functional materials, and particularly relates to a plastic-free food packaging paper with water and oil barrier and anti-sticking properties, its preparation method and application. The plastic-free food packaging paper adopts a multi-layer composite structure design, including an inner layer, an intermediate layer and a surface layer which are sequentially laminated; the inner layer is a base paper layer, the intermediate layer is a starch layer, and the surface layer is a waterproof and oil-proof barrier coating; the waterproof and oil-proof barrier coating is prepared by coating a mixture of an aqueous acrylic resin emulsion and a biodegradable filler; the biodegradable filler can specifically be a biodegradable ester material, and the waterproof and oil-proof barrier coating realizes the barrier to water and oil. The plastic-free food packaging paper has good properties such as oil resistance, water resistance, and anti-sticking, and the materials used are non-toxic, environmentally friendly, can be directly contacted with food, and the pulp can be completely recycled. At the same time, the preparation method is simple, the reaction time is short, and it is easy to promote, so it has good practical application value.

Description

Technical Field

[0001] The present invention belongs to the technical field of food packaging functional materials, and particularly relates to a plastic-free food packaging paper with water and oil barrier and anti-sticking properties, and a preparation method and application thereof. Background Art

[0002] Disclosing the information of this background art section is only intended to enhance the overall understanding of the present invention, and is not necessarily regarded as an admission or an indication in any form that this information constitutes the prior art already known to those of ordinary skill in the art.

[0003] In the field of food packaging, the water and oil barrier properties of packaging paper play a very important role. However, ordinary paper is formed by fibers, and its internal natural polyhydroxy structure and capillary action result in poor water barrier ability of the paper. At present, the commonly used methods for improving the water and oil barrier properties of paper mainly include aluminum-plastic composite and plastic film coating.

[0004] Currently, on the premise of avoiding the use of aluminum-plastic composite to prepare high-barrier packaging paper, some new high-barrier materials and packaging paper products have been continuously developed. For example, Patent CN113389060A discloses a coated cloth for food packaging prepared from styrene-acrylic emulsion and artificial viscose fiber. This coated cloth has achieved good water and oil barrier effects. However, the inventor found that its preparation process is relatively complex and its biodegradability is not ideal. Patent CN105001459A prepared a fully biodegradable plastic film using twelve raw materials including corn starch, peanut oil, and sodium alginate. Although this film can be biodegradable when applied in the field of food packaging, the inventor found that its water and oil barrier effects are still quite different from those of aluminum-plastic composite packaging paper.

[0005] Meanwhile, there is also a very serious problem of coating anti-sticking when using waterborne acrylic emulsion as a barrier functional coating. In a high-humidity and high-temperature environment, there will be a serious adhesion phenomenon between the barrier coating and the printing coating on the non-coated surface. When the paper is separated, products such as printing ink will remain on the food-contact barrier coating surface, which will produce an adverse visual effect and pose a potential food health and safety hazard. Summary of the Invention

[0006] Aiming at the problems of non-biodegradability of existing plastic film-coated packaging paper and anti-sticking of waterborne acrylic resin emulsion-coated paper in high-humidity and high-temperature environments, the inventor has conducted long-term technical and practical explorations and provided a plastic-free food packaging paper with water and oil barrier and anti-sticking properties, and a preparation method and application thereof. The materials used in the present invention are non-toxic, environmentally friendly, and biodegradable, the preparation method is simple, and it can be in direct contact with food, and at the same time has good oil barrier, water barrier, anti-back adhesion and other properties. Based on the above research results, the present invention is thus completed.

[0007] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0008] The first aspect of the present invention provides a food plastic substitute packaging paper that is water-resistant, oil-resistant and anti-sticky. The food plastic substitute packaging paper adopts a multi-layer composite structure design, including an inner layer, an intermediate layer and a surface layer composited in sequence; wherein the inner layer is a base paper layer, the intermediate layer is a starch layer, and the surface layer is a waterproof and oil-proof barrier coating; the main purpose of providing the starch layer is to provide a smooth interface for the high-barrier layer, thereby facilitating the film formation of functional materials; the waterproof and oil-proof barrier coating is prepared by mixing an aqueous acrylic resin emulsion with a biodegradable filler and then applying the mixture; the biodegradable filler can specifically be a biodegradable ester material, and the waterproof and oil-proof barrier coating can achieve water and oil barrier.

[0009] The second aspect of the present invention provides a method for preparing water-resistant, oil-resistant and anti-sticking food plastic substitute packaging paper. The preparation method comprises: coating a starch layer on a base paper layer and drying it. It should be noted that the paper layer needs to be kept flat and free of wrinkles to avoid affecting the subsequent application of a waterproof and oil-proof barrier coating; then, a biodegradable filler is added to an aqueous acrylic resin emulsion for single-layer or double-layer coating, and the paper is obtained after drying.

[0010] The third aspect of the present invention provides the application of the above-mentioned food plastic substitute packaging paper in the field of food packaging.

[0011] Compared with the existing technical solutions, the above one or more technical solutions have the following beneficial effects:

[0012] The water-resistant, oil-resistant and anti-sticking food plastic substitute packaging paper prepared by the above technical solution has good oil-resistant, water-resistant and anti-sticking properties, and the materials used are non-toxic and environmentally friendly, can be in direct contact with food, and the pulp can be completely recycled.

[0013] At the same time, the above technical solution has a simple preparation method, a short reaction time, and is easy to promote. Therefore, it can effectively replace the current plastic film packaging materials and has good practical application value. DETAILED DESCRIPTION

[0014] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0015] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they specify the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0016] Specifically, in a typical specific embodiment of the present invention, a plastic-free food packaging paper that can resist water, oil, and anti-sticking is provided. The plastic-free food packaging paper adopts a multi-layer composite structure design, including an inner layer, an intermediate layer, and a surface layer that are sequentially laminated; wherein, the inner layer is a base paper layer, the intermediate layer is a starch layer, and the surface layer is a waterproof and oil-proof barrier coating; the main purpose of setting the starch layer is to provide a flat interface for the high-barrier layer, thereby facilitating the film formation of functional materials; the waterproof and oil-proof barrier coating is prepared by mixing an aqueous acrylic resin emulsion with a biodegradable filler; the biodegradable filler can specifically be a biodegradable ester material, and the waterproof and oil-proof barrier coating realizes the barrier to water and oil.

[0017] In another specific embodiment of the present invention, the starch raw material used in the starch layer can be ordinary natural starch or modified starch. Among them, the ordinary natural starch includes potato starch, bean starch, cereal starch, and other vegetable starches; the modified starch includes anionic starch, cationic starch, amphoteric starch, multi-component modified starch, non-ionic starch, and other modified starches; in order to make the industrial cost of the present invention lower, in a specific embodiment of the present application, ordinary natural starch is used.

[0018] In another specific embodiment of the present invention, the coating amount of the starch layer is 0.5 g / m 2 ~1.5 g / m 2 .

[0019] In another specific embodiment of the present invention, the biodegradable filler includes water-repellent compounds such as polycaprolactone, glycerol monostearate, triglyceride vegetable oil, neopentyl glycol dioleate, trimethylolpropane trioleate, ethylene glycol monooleate epoxide, epoxidized soybean oil, etc. and ultra-large flaky barrier clay.

[0020] In another specific embodiment of the present invention, the biodegradable ester materials used in the waterproof and oil-proof barrier coating include one or more of glycerol monostearate, triglyceride vegetable oil, epoxidized soybean oil, etc., and their industrial cost is lower.

[0021] The addition amount of the biodegradable filler is 1% - 10% of the mass of the acrylic resin, and further 2% - 6%.

[0022] In another specific embodiment of the present invention, the waterproof and oil-proof barrier coating is obtained by coating with a single-layer or double-layer aqueous acrylic resin emulsion containing biodegradable fillers.

[0023] When using single-layer coating, the aqueous acrylic resin emulsion is a core-shell type aqueous acrylic resin emulsion with a solid content of 30% to 50%, and the core and shell have different glass transition temperatures. The monomers used in the aqueous acrylic resin emulsion include any one or more of butyl acrylate, butyl methacrylate, methyl methacrylate, 2-ethylhexyl acrylate, styrene, α-methylstyrene, and isooctyl methacrylate. Further, the monomers of the aqueous acrylic resin emulsion are a combination of butyl acrylate, butyl methacrylate, methyl methacrylate, styrene, and α-methylstyrene.

[0024] In another specific embodiment of the present invention, the glass transition temperature of the core-shell type aqueous acrylic resin emulsion is 30°C to 60°C, preferably 30°C to 45°C.

[0025] When using double-layer coating, the glass transition temperatures of the aqueous acrylic resin emulsion for the bottom layer coating and the aqueous acrylic resin emulsion for the outer layer coating are different, with a solid content of 30% to 50%. The monomers used include various combinations of methacrylic acid, butyl acrylate, butyl methacrylate, methyl methacrylate, 2-ethylhexyl acrylate, acrylamide, styrene, acrylic acid, α-methylstyrene, isooctyl acrylate, isooctyl methacrylate, etc. Preferably, the monomers used are a combination of methacrylic acid, butyl acrylate, butyl methacrylate, styrene, acrylamide, isooctyl acrylate, and α-methylstyrene.

[0026] In another specific embodiment of the present invention, for the two aqueous acrylic resin emulsions, the resin glass transition temperature of the aqueous acrylic resin emulsion for the bottom layer coating is 10°C to 30°C, and the resin glass transition temperature of the aqueous acrylic resin emulsion for the outer (top) layer coating is 60°C to 80°C.

[0027] The coating amount of the waterproof and oil-proof barrier coating is 5 g / m 2 ~10 g / m 2 .

[0028] In another specific embodiment of the present invention, a method for preparing a food plastic-free packaging paper that can prevent water and oil and resist anti-sticking is provided. The preparation method includes: coating a starch layer on the base paper layer and drying it. It should be noted that it needs to be kept flat without wrinkles to avoid affecting the subsequent coating of the waterproof and oil-proof barrier coating; then, a single-layer or double-layer coating is performed by adding biodegradable fillers to the aqueous acrylic resin emulsion, and it is obtained after drying.

[0029] The drying condition is drying for 0.5 - 3 min under the condition of 105 - 120°C.

[0030] When the aqueous acrylic resin emulsion is a core - shell acrylic resin emulsion, a single - layer coating method is adopted; when the aqueous acrylic resin emulsion is a non - core - shell acrylic resin emulsion, a double - layer coating method is adopted, and the glass transition temperature of the non - core - shell aqueous acrylic resin emulsion for the bottom layer coating is lower than that of the non - core - shell aqueous acrylic resin emulsion for the outer layer coating. Further, the resin glass transition temperature of the aqueous acrylic resin emulsion for the bottom layer coating is 10°C - 30°C, and the resin glass transition temperature of the aqueous acrylic resin emulsion for the outer layer coating is 60°C - 80°C. Through experiments, it is proved that the single - layer coating method using the above - mentioned core - shell aqueous acrylic resin emulsion or the double - layer coating method using the above - mentioned non - core - shell aqueous acrylic resin emulsions with different glass transition temperatures can effectively solve the problem of back - sticking.

[0031] In another specific embodiment of the present invention, the application of the above food - replacing plastic packaging paper in the field of food packaging is provided.

[0032] The following further illustrates the present invention with specific examples. The following examples are only for explaining the present invention and do not limit its content. Any simple modification, equivalent change and modification made to the embodiments according to the technical essence of the present invention all fall within the scope of the technical solution of the present invention.

[0033] Example 1

[0034] Firstly, 0.81 g / m 2 of gelatinized starch is coated on a thin paper with a basis weight of 30 g / m 2 and dried, and attention should be paid to keeping the surface flat without wrinkles to avoid affecting the coating of the waterproof and oil - proof barrier coating. Then, 10% of super - large flaky Steamplus barrier clay is dispersed in the prepared core - shell aqueous acrylic resin emulsion (glass transition temperature is 37.4°C), and after being uniformly dispersed at 400 rpm, it is coated on the starch layer, and the coating amount is 9.88 g / m 2 . After drying at 105°C for 2 min, a food - replacing plastic packaging paper with water - and oil - resistance and anti - back - sticking properties is successfully prepared. It has good heat - sealing performance and can be used for the production of packaging containers such as disposable packaging papers, bags, and boxes.

[0035] Table 1 Monomer composition of the core - shell aqueous acrylic resin emulsion in this example

[0036]

[0037] Example 2

[0038] Coat 30 g / m 2 of tissue paper with 0.75 g / m 2 of gelatinized starch and dry it. Pay attention to keep the surface flat without wrinkles to avoid affecting the coating of the waterproof and oil-proof barrier coating. Then, evenly disperse 10% of triglyceride stearate in the prepared core-shell type waterborne acrylic resin emulsion (glass transition temperature is 31.6 °C). After mixing evenly at a stirring speed of 400 rpm, coat it on the starch layer, and the coating amount is 10.47 g / m 2 . After drying at 120 °C for 0.5 min, a food plastic-free packaging paper with water and oil resistance and anti-sticking properties is successfully prepared. It has good heat-sealing performance and can be used for the production of disposable packaging papers, bags, boxes and other packaging containers.

[0039] Table 2 Monomer composition of the core-shell type waterborne acrylic resin emulsion in this example

[0040]

[0041] Example 3

[0042] Coat 30 g / m 2 of tissue paper with 0.79 g / m 2 of gelatinized starch and dry it. Pay attention to keep the surface flat without wrinkles to avoid affecting the coating of the waterproof and oil-proof barrier coating. Then, evenly disperse 5% of epoxy soybean oil in the primer waterborne acrylic resin emulsion with a glass transition temperature of 29.9 °C and the topcoat waterborne acrylic resin emulsion with a glass transition temperature of 60.0 °C. After mixing evenly at a stirring speed of 400 rpm, coat it on the starch layer. The coating amount of the primer resin is 7.05 g / m 2 . After drying at 110 °C for 1 min, then coat 3.25 g / m 2 of the high glass transition temperature resin emulsion. After drying under the same drying conditions, a food plastic-free packaging paper with water and oil resistance and anti-sticking properties is successfully prepared. It has good heat-sealing performance and can be used for the production of disposable packaging papers, bags, boxes and other packaging containers.

[0043] Table 3 Monomer composition of the two non-core-shell type waterborne acrylic resin emulsions in this example

[0044]

[0045] Effect verification

[0046] The waterproof, oil-proof, anti-sticking, and biodegradability tests were carried out on the food substitute plastic packaging paper prepared in the above embodiments. Among them, the Cobb120s experimental method was used for the waterproof test, the Kit method was used for the oil-proof test to detect the oil-proof grade, and the anti-sticking test was carried out in a high-temperature and high-humidity test chamber (62 °C, 70% humidity, putting the coated surface and the original paper surface together, applying a load so that the paper was under a pressure of 500 Pa, and standing for 24 h), and the anti-sticking phenomenon was observed. The biodegradability was tested by a 90-day biodegradation experiment (GB / T 19276.1-2003). The experimental results are shown in Table 4.

[0047] Table 4 Test results of the food substitute plastic packaging paper of each embodiment

[0048]

[0049] As can be seen from the results in Table 4, the food substitute plastic packaging paper prepared by the present invention has good water resistance, oil resistance, and anti-sticking properties, and at the same time has a good biodegradation rate, is green, safe, and environmentally friendly, and is very suitable for large-scale popularization and application. At the same time, from the results of each embodiment, it can be seen that the food substitute plastic packaging paper prepared in Embodiment 2 has the best comprehensive performance. It not only has the lowest Cobb120 value, indicating its most excellent waterproof performance, but also has the highest biodegradation rate.

[0050] The above are only the preferred embodiments of the present application and are not used to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A food plastic-free wrapping paper that can resist water, oil and anti-sticking, characterized in that, The plastic-free food packaging paper adopts a multi-layer composite structure design, including an inner layer, a middle layer and a surface layer which are sequentially laminated; wherein, the inner layer is a base paper layer, the middle layer is a starch layer, and the surface layer is a waterproof and oil-proof barrier coating; the waterproof and oil-proof barrier coating is prepared by coating a mixture of an aqueous acrylic resin emulsion and a biodegradable filler; the biodegradable filler is a biodegradable ester material; The waterproof and oil-proof barrier coating is obtained by double-layer coating with an aqueous acrylic resin emulsion containing a biodegradable filler; During double-layer coating, the glass transition temperature of the aqueous acrylic resin emulsion for bottom layer coating is lower than that of the aqueous acrylic resin emulsion for outer layer coating, the solid content is 30% - 50%, and the monomers used include various combinations of methacrylic acid, butyl acrylate, butyl methacrylate, methyl methacrylate, 2-ethylhexyl acrylate, acrylamide, styrene, acrylic acid, α-methylstyrene, isooctyl acrylate, isooctyl methacrylate; There are two kinds of aqueous acrylic resin emulsions. The resin glass transition temperature of the aqueous acrylic resin emulsion for bottom layer coating is 29.9 °C, and the resin glass transition temperature of the aqueous acrylic resin emulsion for outer layer coating is 60 °C - 80 °C; The biodegradable filler includes polycaprolactone, glycerol stearate, triglyceride vegetable oil, neopentyl glycol dioleate, trimethylolpropane trioleate, ethylene glycol epoxyoctanoate, epoxidized soybean oil.

2. The food plastic-free wrapping paper according to claim 1, characterized in that, The monomers used are a combination of methacrylic acid, butyl acrylate, butyl methacrylate, styrene, acrylamide, isooctyl acrylate and α-methylstyrene.

3. The food substitute plastic wrapping paper according to claim 1, characterized in that, The starch raw material used in the starch layer is ordinary natural starch or modified starch. Among them, the ordinary natural starch includes potato starch, bean starch, cereal starch; the modified starch includes anionic starch, cationic starch, multi-modified starch, non-ionic starch.

4. The food substitute plastic wrapping paper according to claim 3, characterized in that, The coating amount of the starch layer is 0.5 g / m 2 to 1.5 g / m 2 .

5. The food substitute plastic wrapping paper according to claim 1, characterized in that, The addition amount of the biodegradable filler is 1% - 10% of the mass of the acrylic resin.

6. The food substitute plastic wrapping paper according to claim 5, characterized in that, The addition amount of the biodegradable filler is 2% - 6% of the mass of the acrylic resin.

7. The food substitute plastic wrapping paper according to claim 1, wherein, The coating amount of the waterproof and oil-proof barrier coating is 5 g / m 2 ~10 g / m 2 .

8. The preparation method of the water-blocking, oil-resistant and anti-sticking food plastic-free wrapping paper according to any one of claims 1-7, characterized in that, The preparation method includes: coating the starch layer on the base paper layer and drying; then adding the biodegradable filler to the aqueous acrylic resin emulsion for double-layer coating, and obtaining the product after drying.

9. The preparation method of the food substitute plastic packaging paper according to claim 8, characterized in that, The drying condition is drying at 105 - 120 °C for 0.5 - 3 min.

10. Application of the plastic-free food packaging paper according to any one of claims 1 - 7 in the field of food packaging.

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