Microwaveable coated paper and paper container

Abstract

The application belongs to the technical field of laminated paper and specifically discloses a microwaveable laminated paper and a paper container. The microwaveable laminated paper comprises paper and a laminated layer, and the laminated layer comprises the following raw materials according to weight parts: 100-110 parts of polylactic acid, 50-60 parts of degradable toughening resin, 20-25 parts of modified talcum powder, 15-18 parts of modified chitosan fiber, 3-5 parts of maleic anhydride grafted polypropylene, 1-2 parts of antioxidant, 2-3 parts of ultraviolet resistance agent and 4-5 parts of pentaerythritol stearate. The microwaveable laminated paper prepared in the application has good high and low temperature resistance, strength and heat sealing property, and the cooperation of various raw material components improves the mechanical property, adhesion and thermal stability of the laminated layer.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of laminated paper, in particular to microwaveable laminated paper and a paper container. BACKGROUND

[0002] Laminated paper is a composite material formed by coating plastic particles (such as polyethylene PE particles) on the surface of paper through a flow coater, and its manufacturing process mainly includes the steps of preparing raw paper, coating process, drying treatment and winding or cutting, and the laminated paper is widely used in the fields of food, medicine and chemical industry.

[0003] Microwaveable laminated paper is a special kind of laminated paper, which can be safely used in a microwave oven and will not produce harmful substances or cause fire due to high temperature. Commonly used raw materials of the microwaveable laminated paper include polylactic acid, polybutylene adipate terephthalate and polyhydroxyalkanoate, which have excellent heat resistance and biodegradability.

[0004] However, the compatibility among polylactic acid, polybutylene adipate terephthalate and polyhydroxyalkanoate is poor, which may cause phase separation of the materials during mixing, form an uneven dispersed phase and reduce the overall strength of the mechanical properties such as tensile and tear of the materials. SUMMARY

[0005] In order to improve the poor mechanical properties of the laminated paper prepared from polylactic acid, the application provides microwaveable laminated paper and a paper container.

[0006] The application provides microwaveable laminated paper, which adopts the following technical scheme:

[0007] The microwaveable laminated paper comprises paper and a laminated layer, and the laminated layer comprises the following raw materials according to weight parts: 100-110 parts of polylactic acid, 50-60 parts of degradable toughening resin, 20-25 parts of modified talcum powder, 15-18 parts of modified chitosan fiber, 3-5 parts of maleic anhydride grafted polypropylene, 1-2 parts of antioxidant, 2-3 parts of anti-ultraviolet agent and 4-5 parts of pentaerythritol stearate.

[0008] By adopting the technical scheme, the polylactic acid has good compatibility, can be well combined with paper, and form a uniform coating layer. The polylactic acid coating layer has good high and low temperature resistance, strength and heat sealing property, can withstand the temperature change of cold and hot liquid without leakage and deformation. The addition of the degradable toughening resin can significantly improve the toughness of the coating layer, make it more resistant to tearing and impact, thereby improving the overall performance of the packaging material. The polylactic acid improves the gas barrier property, mechanical property, moisture resistance and heat sealing property of the coating layer. The modified talc powder has a lamellar structure, can form a layered dispersion in the coating layer, provides excellent mechanical property support for the coating layer, significantly improves the barrier property of the coating paper, and improves the thermal stability of the coating layer, so that it can still maintain good performance in a high temperature environment.

[0009] The modified chitosan fiber has excellent antibacterial property, high strength and toughness, can be tightly combined with the plastic substrate to form a stable structure, improve the tensile strength, tearing strength and puncture resistance of the product, and significantly improve the mechanical property of the coating layer. The modified talc powder is mixed with the modified chitosan fiber, the modified talc powder can be loaded on the surface of the modified chitosan fiber, improve the compactness of the raw material, and improve the mechanical property of the coating layer. The maleic anhydride grafted polypropylene has good compatibility, improves the heat resistance, weather resistance, tensile and impact strength of the coating layer, significantly improves the adhesion between the coating layer and the paper, ensures the tight combination between the coating layer and the substrate, and thereby improves the overall strength and durability of the product.

[0010] The antioxidant can protect the material property of the coating layer, prevent it from being reduced due to oxidation, delay the progress of the oxidation reaction, significantly prolong the service life, and improve the weather resistance and stability. The ultraviolet resistant agent can absorb ultraviolet energy and convert it into heat energy or other harmless forms, thereby avoiding the direct damage of ultraviolet to the coating layer material, maintaining its original physical and chemical properties, and prolonging the service life. The pentaerythritol stearate has good lubricity and demolding property, which can significantly reduce the friction and adhesion between the materials in the coating layer, promote the flow of the plastic during the coating process, reduce the adhesion between the mold and the material, thereby improving the production efficiency and product quality.

[0011] Preferably, the preparation method of the modified talc powder comprises the following steps:

[0012] (1) dispersing the talc powder in a dilute nitric acid solution, stirring at room temperature for 30-40 min, washing with water, then dispersing in ethanol, adding a titanate coupling agent, stirring at a temperature of 60-65℃ for 1-2h, filtering, and drying to obtain a pretreated talc powder;

[0013] (2) The modified corn straw is dispersed in deionized water, the pretreated talcum powder and nano-silicon dioxide in step (1) are added, stirring at 80-85℃ for 2-3h, drying, grinding, to obtain modified talcum powder.

[0014] By using the above technical scheme, the talcum powder is treated by dilute nitric acid solution, some unnecessary substances are dissolved or reacted by dilute nitric acid, the impurities on the surface of the talcum powder are removed, the talcum powder is dispersed in ethanol, and the titanate coupling agent is added, the titanate coupling agent reacts with the functional groups such as hydroxyl groups on the surface of the talcum powder to form chemical bonds, thereby improving the compatibility and dispersibility of the talcum powder with organic matter; after the treatment of the titanate coupling agent, new functional groups are introduced on the surface of the talcum powder, which improves the compatibility and dispersibility of the talcum powder with organic matter.

[0015] The modified corn straw is dispersed in deionized water, the modified corn straw has good compatibility, air permeability, strength and toughness, the pretreated talcum powder has a sheet structure and can form an effective barrier layer to improve the barrier properties of the coating layer to gas, moisture and the like, and prolong the freshness and shelf life of the packaged goods; the addition of the pretreated talcum powder can enhance the mechanical properties such as tensile strength and tear strength of the coating layer, so that the coating layer is less likely to be damaged when subjected to external force, and the durability of the package is improved. Nano-silicon dioxide has a very high specific surface area and activity, and can form a close combination with other components in the coating layer, thereby improving the overall strength and toughness of the coating layer, so that the coating layer can better resist deformation and damage when subjected to external force. Nano-silicon dioxide has excellent dispersibility and stability, and can be uniformly distributed in the coating layer to avoid agglomeration and sedimentation.

[0016] Nano-silicon dioxide can be loaded in the structure of talcum powder, and the modified corn straw can be closely combined with nano-silicon dioxide and talcum powder, thereby improving the mechanical properties, wear resistance and barrier properties of the modified talcum powder, and the subsequent application in the coating layer improves the overall strength and toughness, wear resistance and aging resistance of the coating layer, prolongs the service life of the coating layer, and reduces the packaging damage problem caused by wear and aging.

[0017] Preferably, the mass ratio of the talcum powder, the modified corn straw and the nano-silicon dioxide is 1:0.4-0.6:0.1-0.2.

[0018] By adopting the technical scheme, the mass ratio of talcum powder, modified corn straw and nano-silicon dioxide is further limited within a certain range, the comprehensive performance of the talcum powder such as the mechanical property, wear resistance and barrier property is improved, the talcum powder has a sheet structure and can enhance the tensile strength and tear strength of the coating layer; the nano-silicon dioxide has a very high specific surface area and activity and can form a close combination with other components in the coating layer, thereby further improving the overall strength and toughness; the modified corn straw also has components such as cellulose which can help to enhance the physical properties of the coating layer. The modified corn straw can be closely combined with the nano-silicon dioxide and the talcum powder, thereby improving the comprehensive performance of the modified talcum powder, and the modified talcum powder is subsequently applied to the coating layer to improve the wear resistance and aging resistance of the coating layer, and the talcum powder and the nano-silicon dioxide can form an effective barrier layer in the coating layer to improve the barrier performance of the coating layer to gas and moisture.

[0019] Preferably, the preparation method of the modified corn straw comprises the following steps: crushing, drying and sieving the corn straw, then dispersing the corn straw in a sodium hydroxide solution, stirring at a temperature of 70-75°C for 40-45 min, washing with water, dispersing the corn straw in deionized water again, adding sodium alginate, nano-silver and xanthan gum, stirring at a temperature of 80-85°C for 2-3 h, drying and grinding to obtain the modified corn straw.

[0020] By adopting the technical scheme, the corn straw is crushed and treated with a sodium hydroxide solution to destroy the lignin and hemicellulose structure in the corn straw, so that the corn straw is more easily combined with other components in the subsequent steps; the corn straw is washed with water to remove residual sodium hydroxide and other impurities. The water-washed corn straw is dispersed in deionized water again, and sodium alginate, nano-silver and xanthan gum are added. The sodium alginate has good viscosity, film-forming property and biocompatibility, can be combined with cellulose in the corn straw to form a complementary fiber network structure, thereby improving the strength and toughness of the system, the nano-silver has antibacterial properties and can be embedded in the network structure formed by the sodium alginate and the cellulose to increase the antibacterial properties of the system, and the xanthan gum is a good thickening agent which can significantly increase the viscosity and stability of the mixture. The sodium alginate, the xanthan gum and the cellulose are cross-linked to form a more stable and uniform structure, and the viscosity and mechanical properties of the system are also increased.

[0021] The modified corn straw is applied to the modified talcum powder, so that the talcum powder is closely bonded with the nano-silicon dioxide, the nano-silicon dioxide is closely bonded in the structure of the talcum powder through the modified corn straw, the mechanical strength and performance stability of the modified talcum powder are improved, and the modified talcum powder is subsequently applied to the coating layer to improve the corresponding performance of the coating layer.

[0022] Preferably, the preparation method of the modified chitosan fiber comprises the following steps:

[0023] (1) Disperse the chitosan fiber in sodium hydroxide solution, stir at 50-55℃ for 1-2h, wash, dry, and obtain the pretreated chitosan fiber;

[0024] (2) Disperse the modified starch in deionized water, add the pretreated chitosan fiber of step (1), sodium hydroxymethyl cellulose, and acetic acid, stir at a temperature of 70-75℃ for 1-2h, and dry to obtain the modified chitosan fiber.

[0025] By using the above technical solution, the chitosan fiber is first pretreated, treated with sodium hydroxide solution, and the reaction between the chitosan fiber and the sodium hydroxide solution removes the acetyl group in the chitosan molecule, thereby improving the ductility and solubility of the fiber; the purpose of washing is to remove the residual sodium hydroxide and other impurities on the surface of the fiber, ensuring the purity of the fiber and the safety of subsequent use.

[0026] Disperse the modified starch in deionized water to form a uniform suspension, add the chitosan fiber, sodium hydroxymethyl cellulose, and acetic acid. The chitosan fiber has good mechanical properties, antibacterial properties, and biocompatibility. The modified starch can coat the chitosan fiber, improve the adhesion and mechanical properties of the chitosan fiber, and the hydroxyl groups of the modified starch can form hydrogen bonds or cross-linking reactions with the amino groups of the chitosan fiber or the hydroxyl groups of the sodium hydroxymethyl cellulose. Acetic acid adjusts the pH value of the system and plays a catalytic role, promoting the progress of these reactions. The addition of sodium hydroxymethyl cellulose can also improve the dispersibility of the fiber and enhance the interaction between the fibers, thereby improving the mechanical properties and stability of the composite material.

[0027] Subsequently applied in the laminated film layer, starch can form a colloidal solution, increase the viscosity of the system, prevent the rapid loss of liquid components, thereby improving the stability and durability of the laminated film layer. Sodium hydroxymethyl cellulose can increase the viscosity of the solution to achieve the purpose of thickening, thereby improving the texture and stability of the laminated film layer. In addition, sodium hydroxymethyl cellulose also has good film-forming properties and can form a protective film on the surface of the laminated film layer to prevent damage to the laminated film layer from the external environment. Chitosan fiber has a wide antibacterial spectrum and high antibacterial activity, which can significantly improve the antibacterial properties of the laminated film layer, prevent the growth and reproduction of microorganisms, and thereby prolong the service life of the laminated film layer.

[0028] Preferably, the mass ratio of the chitosan fiber, modified starch, and sodium hydroxymethyl cellulose is 1:0.3-0.5:0.08-0.09.

[0029] By adopting the technical scheme, the mass ratio of the chitosan fiber, the modified starch and the sodium hydroxymethyl cellulose is further limited in a certain range, the obtained chitosan fiber has better mechanical properties and antibacterial properties, the modified starch can coat the chitosan fiber, improve the mechanical properties and viscosity of the chitosan fiber, and the sodium hydroxymethyl cellulose makes the chitosan fiber and the modified starch further bond, thereby improving the comprehensive performance of the system.

[0030] The chitosan fiber has excellent mechanical properties and biocompatibility, the hydroxyl groups of the modified starch can form hydrogen bonds or cross-linking reactions with the amino groups of the chitosan fiber or the hydroxyl groups of the sodium hydroxymethyl cellulose, thereby enhancing the strength and toughness of the film layer and improving the water resistance and weather resistance of the film layer. As a thickening agent and stabilizer, the sodium hydroxymethyl cellulose can increase the cohesion of the film layer, so that the film layer is more compact and tough. The thickening effect of the sodium hydroxymethyl cellulose can improve the coatability and uniformity of the film layer, so that the film layer is more easily processed and applied.

[0031] Preferably, the preparation method of the modified starch comprises the following steps: dispersing waxy rice starch in a sodium hydroxide solution, stirring at 60-65℃ for 1-2h, centrifuging the starch milk, pouring off the supernatant, adding water, shaking and centrifuging, repeating the operation until the starch milk becomes neutral, filtering and drying the starch milk to obtain pretreated starch, then dispersing the starch in deionized water, adding calcium carbonate and montmorillonite, stirring at 80-85℃ for 2-3h, drying and grinding to obtain the modified starch.

[0032] By adopting the technical scheme, the waxy rice starch is dispersed in a sodium hydroxide solution, which causes the internal fracture of the starch molecules and the formation of cross-linking structures, so that the starch molecules are converted from a granular structure to a uniform colloidal structure. Centrifugation can remove excess water and unreacted sodium hydroxide in the starch milk, and the obtained pretreated starch improves the viscosity and uniformity of the starch.

[0033] The starch is dispersed in water to form a starch emulsion. Calcium carbonate has high hardness and stability, can be embedded in the starch structure, and increase the hardness and density of the whole system. The surface of montmorillonite has a large number of hydroxyl groups and negative charges, which can adsorb cations and organic molecules in water, and at the same time promote the dispersion of calcium carbonate and starch, thereby helping to enhance the uniformity and stability of the mixture.

[0034] The hydroxyl groups on the starch molecular chains can interact with the calcium ions on the surface of calcium carbonate or the hydroxyl groups on the surface of montmorillonite, forming a cross-linked structure, which helps to improve the stability and mechanical strength of the mixture. The calcium carbonate particles in the mixed system are wrapped by the starch colloid to form a starch-calcium carbonate composite. This composite helps to prevent the agglomeration and sedimentation of calcium carbonate particles and improves the uniformity of the mixture. Starch, calcium carbonate and montmorillonite can form a synergistic reinforcing effect in the mixture, and the interaction between them can enhance the mechanical strength, heat resistance and stability of the whole system. Subsequently applied in the lamination layer, the adhesion between the lamination layer and the substrate is enhanced, and the mechanical properties, wear resistance, barrier property and heat resistance of the lamination layer are improved.

[0035] Preferably, the degradable toughening resin is selected from at least one of polyhydroxyalkanoate, polybutylene succinate, polybutylene terephthalate-co-adipate, and polyhydroxybutyrate.

[0036] By adopting the above technical scheme, the degradable toughening resin enhances the toughness of the material, which can effectively improve the impact strength and tear resistance of the lamination layer, making it more durable and less likely to be damaged when facing external forces.

[0037] In a second aspect, the application also provides a preparation method of a microwaveable laminated paper, comprising the following steps:

[0038] Mix polylactic acid, degradable toughening resin, modified talc powder, modified chitosan fiber, maleic anhydride grafted polypropylene, antioxidant, ultraviolet resistant agent, and pentaerythritol stearate to obtain a premixed raw material;

[0039] The premixed raw material is extruded and granulated to obtain a composite modified master batch;

[0040] The composite modified master batch is dried, and then cast coated with paper to obtain a microwaveable laminated paper.

[0041] By adopting the above technical scheme, the above preparation method is adopted, the process time is short, the operation is simple, which helps to improve the production efficiency of the laminated paper, and the microwaveable laminated paper obtained has good comprehensive properties such as mechanical properties and stability.

[0042] In a third aspect, the application also provides a paper container, which comprises a container body, the inner and outer walls of the container body are bonded with the laminated paper prepared above, and the adhesive used for bonding is an acrylic resin.

[0043] In summary, the application has the following beneficial effects:

[0044] 1、The polylactic acid in the application has good compatibility and can be well combined with paper to form a uniform laminated film. The polylactic acid laminated film has good high and low temperature resistance, strength and heat sealing property, and can withstand temperature changes of cold and hot liquids without leakage and deformation.

[0045] 2、The modified talc powder in the application has a lamellar structure and can form a laminated dispersion in the laminated film, providing excellent mechanical property support for the laminated film, significantly improving the barrier property of the laminated base paper, improving the thermal stability of the laminated film, and enabling it to maintain good performance in a high temperature environment.

[0046] 3、The modified chitosan fiber in the application has excellent antibacterial property, high strength and toughness, can be tightly combined with plastic substrates to form a stable structure, improve the tensile strength, tear strength and puncture resistance of the product, and significantly improve the mechanical properties of the laminated film. DETAILED DESCRIPTION

[0047] The application will be further described in detail below in combination with examples.

[0048] The raw materials used in the examples and comparative examples can be obtained by market purchase.

[0049] Preparation example of modified talc powder

[0050] Preparation example 1-1

[0051] The preparation method of the modified talc powder comprises the following steps:

[0052] (1) Disperse 50 kg of talc powder in 70 L of 20% mass fraction dilute nitric acid solution, stir at room temperature for 35 min, wash with water, then disperse in 80 L of ethanol, add titanium ester coupling agent HY401, stir at a temperature of 65℃ for 2 h, filter, dry, and obtain pretreated talc powder;

[0053] (2) Disperse the modified corn straw in 80 L of deionized water, add the pretreated talc powder of step (1) and nano silicon dioxide, stir at a temperature of 85℃ for 3 h, dry, grind, and obtain modified talc powder.

[0054] The mass ratio of talc powder, modified corn straw and nano silicon dioxide is 1:0.4:0.2.

[0055] The preparation method of the modified corn straw comprises the following steps: 100 kg of corn straw is crushed, dried, and then dispersed in 120 L of a 10% sodium hydroxide solution, stirred at 75 DEG C for 45 min, washed with water, then dispersed in 150 L of deionized water, 25 kg of sodium alginate, 30 kg of nano-silver and 20 kg of xanthan gum are added, stirred at 85 DEG C for 3 h, dried, ground, and the modified corn straw is obtained.

[0056] Preparation Example 1-2

[0057] The difference from Preparation Example 1-1 is that in step (2), the modified corn straw is not added.

[0058] Preparation Example 1-3

[0059] The difference from Preparation Example 1-1 is that in step (2), the nano-silicon dioxide is not added.

[0060] Preparation Example 1-4

[0061] The difference from Preparation Example 1-1 is that the mass ratio of talcum powder, modified corn straw and nano-silicon dioxide is 1:0.6:0.1.

[0062] Preparation Example 1-5

[0063] The difference from Preparation Example 1-1 is that the mass ratio of talcum powder, modified corn straw and nano-silicon dioxide is 1:0.1:0.7.

[0064] Preparation Example 1-6

[0065] The difference from Preparation Example 1-1 is that in the preparation method of the modified corn straw, the sodium alginate is not added.

[0066] Preparation Example 1-7

[0067] The difference from Preparation Example 1-1 is that in the preparation method of the modified corn straw, the nano-silver is not added.

[0068] Preparation Example 1-8

[0069] The difference from Preparation Example 1-1 is that in the preparation method of the modified corn straw, the xanthan gum is not added.

[0070] Preparation Example of Modified Chitosan Fiber

[0071] Preparation Example 2-1

[0072] The preparation method of the modified chitosan fiber comprises the following steps:

[0073] (1) 30 kg of chitosan fiber was dispersed in 50 L of 0.8 mol / L sodium hydroxide solution, stirred at 55°C for 2 h, washed, and dried to obtain pretreated chitosan fiber;

[0074] (2) The modified starch was dispersed in 90 L of deionized water, and the pretreated chitosan fiber, sodium hydroxymethyl cellulose, and 10 L of acetic acid of step (1) were added, stirred at a temperature of 75°C for 2 h, and dried to obtain modified chitosan fiber.

[0075] The mass ratio of chitosan fiber, modified starch, and sodium hydroxymethyl cellulose was 1:0.3:0.09.

[0076] The preparation method of the modified starch comprises the following steps: 30 kg of waxy rice starch was dispersed in 50 L of 0.05% sodium hydroxide solution, stirred at 65°C for 2 h, the starch milk was centrifuged, the supernatant was poured out, and then water was added, shaken, and centrifuged, and the operation was repeated until the starch milk became neutral. The starch milk was filtered and dried to obtain pretreated starch. Then the pretreated starch was dispersed in 90 L of deionized water, 10 kg of calcium carbonate and 15 kg of montmorillonite were added, stirred at 85°C for 3 h, dried, and ground to obtain modified starch.

[0077] Preparation Example 2-2

[0078] The difference from Preparation Example 2-1 is that no modified starch is added in step (2).

[0079] Preparation Example 2-3

[0080] The difference from Preparation Example 2-1 is that no sodium hydroxymethyl cellulose is added in step (2).

[0081] Preparation Example 2-4

[0082] The difference from Preparation Example 2-1 is that the mass ratio of chitosan fiber, modified starch, and sodium hydroxymethyl cellulose is 1:0.5:0.08.

[0083] Preparation Example 2-5

[0084] The difference from Preparation Example 2-1 is that the mass ratio of chitosan fiber, modified starch, and sodium hydroxymethyl cellulose is 1:0.1:0.2.

[0085] Preparation Example 2-6

[0086] The difference from Preparation Example 2-1 is that no calcium carbonate is added in the preparation method of the modified starch.

[0087] Preparation Example 2-7

[0088] The difference from Preparation Example 2-1 is that no montmorillonite is added in the preparation method of the modified starch.

[0089] Embodiment

[0090] Embodiment 1

[0091] A microwaveable laminated paper, comprising paper and a laminated layer, the laminated layer comprising, by weight, polylactic acid 100 kg, degradable toughening resin 50 kg, modified talc powder 20 kg, modified chitosan fiber 15 kg, maleic anhydride grafted polypropylene 3 kg, antioxidant 1 kg, ultraviolet resistant agent 2 kg, and pentaerythritol stearate 5 kg.

[0092] The degradable toughening resin is polyhydroxyalkanoate, the antioxidant is antioxidant 1010, and the ultraviolet resistant agent is UV-360, which is purchased from Nanjing Milan Chemical Co., Ltd.

[0093] A preparation method of the microwaveable laminated paper, comprising the following steps: placing polylactic acid, degradable toughening resin, modified talc powder, modified chitosan fiber, maleic anhydride grafted polypropylene, antioxidant, ultraviolet resistant agent, and pentaerythritol stearate into a dry blender to mix, to obtain pre-mixed raw materials;

[0094] The pre-mixed raw materials are put into a double-screw extruder to be extruded and granulated, to obtain a composite modified master batch;

[0095] The composite modified master batch is dried, and then cast coated with paper to obtain the microwaveable laminated paper.

[0096] When the pre-mixed raw materials are put into the double-screw extruder to be extruded and granulated, the temperature of the mixing area is set to be 120℃, 170℃, 200℃, 200℃, 180℃, and 170℃ in sequence; the temperature of the cast coating is 180℃, and the thickness of the laminated layer is 10μm.

[0097] The modified talc powder is prepared by the preparation example 1-1, and the modified chitosan fiber is prepared by the preparation example 2-1.

[0098] Embodiment 2

[0099] A microwaveable laminated paper, which is different from the embodiment 1 in that the laminated layer comprises, by weight, polylactic acid 110 kg, degradable toughening resin 60 kg, modified talc powder 25 kg, modified chitosan fiber 18 kg, maleic anhydride grafted polypropylene 5 kg, antioxidant 2 kg, ultraviolet resistant agent 3 kg, and pentaerythritol stearate 4 kg.

[0100] Embodiment 3

[0101] A microwaveable laminated paper, which is different from the embodiment 1 in that the modified talc powder is prepared by the preparation example 1-2.

[0102] Embodiment 4

[0103] A microwaveable laminated paper, which differs from Example 1 in that the modified talc powder is prepared using Preparation Example 1-3.

[0104] Example 5

[0105] A microwaveable laminated paper, which differs from Example 1 in that the modified talc powder is prepared using Preparation Example 1-4.

[0106] Example 6

[0107] A microwaveable laminated paper, which differs from Example 1 in that the modified talc powder is prepared using Preparation Example 1-5.

[0108] Example 7

[0109] A microwaveable laminated paper, which differs from Example 1 in that the modified talc powder is prepared using Preparation Example 1-6.

[0110] Example 8

[0111] A microwaveable laminated paper, which differs from Example 1 in that the modified talc powder is prepared using Preparation Example 1-7.

[0112] Example 9

[0113] A microwaveable laminated paper, which differs from Example 1 in that the modified talc powder is prepared using Preparation Example 1-8.

[0114] Example 10

[0115] A microwaveable laminated paper, which differs from Example 1 in that the modified chitosan fiber is prepared using Preparation Example 2-2.

[0116] Example 11

[0117] A microwaveable laminated paper, which differs from Example 1 in that the modified chitosan fiber is prepared using Preparation Example 2-3.

[0118] Example 12

[0119] A microwaveable laminated paper, which differs from Example 1 in that the modified chitosan fiber is prepared using Preparation Example 2-4.

[0120] Example 13

[0121] A microwaveable laminated paper, which differs from Example 1 in that the modified chitosan fiber is prepared using Preparation Example 2-5.

[0122] Example 14

[0123] A microwaveable laminated paper, which differs from Example 1 in that the modified chitosan fiber is prepared using Preparation Example 2-6.

[0124] Example 15

[0125] A microwaveable laminated paper, which is different from Example 1 in that the modified chitosan fiber is prepared by Preparation Example 2-7.

[0126] Comparative Example

[0127] Comparative Example 1

[0128] A microwaveable laminated paper, which is different from Example 1 in that no modified talc powder is added.

[0129] Comparative Example 2

[0130] A microwaveable laminated paper, which is different from Example 1 in that the modified talc powder is replaced by an equal amount of talc powder.

[0131] Comparative Example 3

[0132] A microwaveable laminated paper, which is different from Example 1 in that no modified chitosan fiber is added.

[0133] Comparative Example 4

[0134] A microwaveable laminated paper, which is different from Example 1 in that the modified chitosan fiber is replaced by an equal amount of chitosan fiber.

[0135] Performance test

[0136] The microwaveable laminated papers prepared by Examples 1-15 and Comparative Examples 1-4 were tested for performance:

[0137] Tensile strength refers to GB / T 12914-2018 "Determination of tensile strength of paper and paperboard-Constant rate of elongation method (20mm / min)", tear resistance refers to GB / T 455-2002 "Determination of tear resistance of paper and paperboard", folding endurance refers to GB / T 457-1989 "Method for determination of folding endurance of paper", and bonding strength refers to GB / T 36392-2018 "Laminated paper and paperboard for food packaging".

[0138] Degradation performance: The sample was buried in soil for degradation test, and GB / T 39951-2021 "Evaluation method for degradation performance of disposable paper products" was referred to. After 45d and 90d, the residual weight was recorded, and the weight loss rate was calculated; the test results are shown in Table 1.

[0139] Table 1 Test data of examples and comparative examples

[0140]

[0141] As shown in Table 1, the prepared laminated paper of Examples 1-2 has good mechanical properties, degradation performance and adhesion, wherein the tensile strength of Example 1 is 4.78 KN.m, the tear strength is 489 mN, the weight loss rates of 45d and 90d are 55.2% and 93.7% respectively, the folding endurance is 151 times, and the adhesion is 35 N / inch. It shows that the prepared laminated layer has good tensile strength and tear strength, and the prepared laminated layer has good adhesion with the paper, which ensures the close combination between the laminated layer and the substrate, thereby improving the overall strength and durability of the product.

[0142] In the preparation methods of modified talc powder of Examples 3-4, no modified corn straw and nano-silicon dioxide are added respectively, and the mass ratio of talc powder, modified corn straw and nano-silicon dioxide is changed in Examples 5-6. As shown in Table 1, the tensile strength, tear strength, weight loss rates of 45d and 90d, folding endurance and adhesion of Examples 3-4 are obviously worse than those of Examples 1-2 and Example 5, and the corresponding performance test of Example 6 is better than that of Examples 3-4 but worse than that of Examples 1-2 and Example 5, which shows that the modified corn straw can be closely combined with nano-silicon dioxide and talc powder to improve the comprehensive performance of the modified talc powder, which is subsequently applied in the laminated layer to improve the wear resistance and anti-aging property of the laminated layer. Talc powder and nano-silicon dioxide can form an effective barrier layer in the laminated layer to improve the mechanical properties and adhesion of the laminated layer.

[0143] In the preparation methods of modified corn straw of Examples 7-9, no sodium alginate, nano-silver and xanthan gum are added respectively. As shown in Table 1, the tensile strength, tear strength, weight loss rates of 45d and 90d, folding endurance and adhesion of Examples 7-9 are obviously better than those of Example 3, but worse than those of Examples 1-2 and Example 5, which shows that sodium alginate has good viscosity, film-forming property and biocompatibility, can be combined with cellulose in corn straw to form a complementary fiber network structure, thereby improving the strength and toughness of the system; nano-silver has antibacterial property, can be embedded in the network structure formed by sodium alginate and cellulose to increase the antibacterial property and mechanical properties of the system; xanthan gum can increase the viscosity and stability of the mixture, and also increase the viscosity and mechanical properties of the system.

[0144] The preparation methods of modified chitosan fibers in Examples 10-11 do not add modified starch and sodium hydroxymethyl cellulose, respectively, and the mass ratio of chitosan fibers, modified starch and sodium hydroxymethyl cellulose is changed in Examples 12-13. As can be seen from Table 1, the tensile strength, tear degree, weight loss rate at 45d and 90d, folding endurance and bonding force of Examples 10-11 are significantly poorer than those of Examples 1-2 and Example 12, and the corresponding performance test of Example 13 is better than that of Examples 10-11 but poorer than that of Examples 1-2 and Example 12, indicating that the chitosan fiber has excellent mechanical properties and biocompatibility, the hydroxyl group of the modified starch can form hydrogen bonding or crosslinking reaction with the amino group of the chitosan fiber or the hydroxyl group of the sodium hydroxymethyl cellulose, thereby enhancing the strength and toughness of the coating layer and improving the water resistance, bonding force, weather resistance and mechanical properties of the coating layer.

[0145] The preparation methods of modified starch in Examples 14-15 do not add calcium carbonate and montmorillonite, respectively. As can be seen from Table 1, the tensile strength, tear degree, weight loss rate at 45d and 90d, folding endurance and bonding force of Examples 14-15 are significantly better than those of Example 10, but poorer than those of Examples 1-2 and Example 12, indicating that calcium carbonate has high hardness and stability, can be embedded in the structure of starch, and increase the hardness and density of the whole system; montmorillonite crosslinks with starch to improve the stability and mechanical strength of the mixture, and is subsequently applied in the coating layer to enhance the adhesion between the coating layer and the substrate, and improve the mechanical properties, wear resistance, barrier property and heat resistance of the coating layer.

[0146] In Comparative Examples 1 and 3, modified talc and modified chitosan fiber are not added, respectively. As can be seen from Table 1, the tensile strength, tear degree, weight loss rate at 45d and 90d, folding endurance and bonding force of Comparative Examples 1 and 3 are significantly poorer than those of Examples 1-2, indicating that the modified talc can form a layered dispersion in the coating layer, providing excellent mechanical property support for the coating layer and improving the stability of the coating layer and maintaining good performance; the modified chitosan fiber has excellent antibacterial performance, high strength and toughness, can be tightly combined with the plastic substrate to form a stable structure, and improve the tensile strength, tear strength and puncture resistance of the product, thereby improving the mechanical properties of the coating layer.

[0147] In Comparative Examples 2 and 4, the modified talc is replaced by an equal amount of talc, and the modified chitosan fiber is replaced by an equal amount of chitosan fiber. As can be seen from Table 1, the tensile strength, tear degree, weight loss rate at 45d and 90d, folding endurance and bonding force of Comparative Examples 2 and 4 are significantly poorer than those of Examples 1-2 but better than those of Comparative Examples 1 and 3, indicating that the modified talc and the modified chitosan fiber of the present application have good mechanical properties, thereby improving the mechanical properties of the coating layer and maintaining the durability and stability of the coating paper.

[0148] The embodiments are only illustrative of the present application, and are not intended to limit the present application, and those skilled in the art can make modifications to the embodiments without creative contribution after reading the specification, but as long as the modifications are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A microwave-safe coated paper, characterized in that, The product includes paper and a coating layer. The coating layer, by weight, comprises the following raw materials: 100-110 parts polylactic acid, 50-60 parts biodegradable toughening resin, 20-25 parts modified talc, 15-18 parts modified chitosan fiber, 3-5 parts maleic anhydride-grafted polypropylene, 1-2 parts antioxidant, 2-3 parts UV stabilizer, and 4-5 parts pentaerythritol stearate. The method for preparing the modified talc powder includes the following steps: (1) Disperse talc powder in dilute nitric acid solution, stir at room temperature for 30-40 min, wash with water, then disperse in ethanol, add titanate coupling agent, stir at 60-65℃ for 1-2 h, filter, dry to obtain pretreated talc powder; (2) Disperse the modified corn stalks in deionized water, add the pretreated talc powder and nano silica from step (1), stir at 80-85℃ for 2-3 hours, dry, grind, and obtain modified talc powder. The method for preparing the modified chitosan fiber includes the following steps: (1) Disperse chitosan fibers in sodium hydroxide solution, stir at 50-55℃ for 1-2 hours, wash and dry to obtain pretreated chitosan fibers; (2) Disperse the modified starch in deionized water, add the pretreated chitosan fiber, sodium hydroxymethyl cellulose and acetic acid from step (1), stir at 70-75℃ for 1-2 hours, and dry to obtain the modified chitosan fiber. The method for preparing the modified corn stalks includes the following steps: crushing and drying the corn stalks, sieving them, dispersing them in a sodium hydroxide solution, stirring them at 70-75℃ for 40-45 minutes, washing them with water, dispersing them again in deionized water, adding sodium alginate, nano silver and xanthan gum, stirring them at 80-85℃ for 2-3 hours, drying them, and grinding them to obtain the modified corn stalks; The method for preparing the modified starch includes the following steps: dispersing glutinous rice starch in sodium hydroxide solution, stirring at 60-65℃ for 1-2 hours, centrifuging the starch milk, discarding the supernatant, adding water and shaking well, centrifuging again, repeating the operation until the starch milk becomes neutral, filtering the starch milk and drying it to obtain pretreated starch, then dispersing the starch in deionized water, adding calcium carbonate and montmorillonite, stirring at 80-85℃ for 2-3 hours, drying, grinding, and obtaining modified starch.

2. The microwave-safe coated paper according to claim 1, characterized in that, The mass ratio of talc, modified corn stalks and nano-silica is 1:0.4-0.6:0.1-0.

2.

3. The microwave-safe coated paper according to claim 1, characterized in that, The mass ratio of chitosan fiber, modified starch, and sodium hydroxymethyl cellulose is 1:0.3-0.5:0.08-0.

09.

4. The microwave-safe coated paper according to claim 1, characterized in that, The biodegradable toughening resin is selected from at least one of polyhydroxy fatty acid ester, polybutylene succinate, poly(adipate-terephthalic acid) cobutylene, and polyhydroxybutyrate.

5. The method for preparing microwave-safe coated paper according to claim 1, characterized in that, Includes the following steps: Polylactic acid, biodegradable toughening resin, modified talc, modified chitosan fiber, maleic anhydride-grafted polypropylene, antioxidant, UV stabilizer, and pentaerythritol stearate are mixed to obtain a premixed raw material. The premixed raw materials are extruded and granulated to obtain composite modified masterbatch; The composite modified masterbatch is dried and then cast and coated with paper to obtain microwave-safe coated paper.

6. A paper container, comprising a container body, characterized in that, The inner and outer walls of the container body are both bonded with the coated paper according to any one of claims 1-5, and the adhesive used for bonding is acrylic resin.

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