A green and environmentally friendly moisture-proof and antibacterial white kraft paper coating and process technology

Abstract

The invention discloses a green and environmentally friendly moisture-proof and antibacterial white kraft paper coating and process technology, wherein the green and environmentally friendly moisture-proof and antibacterial white kraft paper coating comprises the following components in parts by weight: 5-15 parts of polyvinyl alcohol aqueous solution, 10-20 parts of carboxymethyl cellulose aqueous solution, 5-8 parts of chitosan aqueous solution, 3-8 parts of gelatin aqueous solution, 1-5 parts of emulsion wax, 2-8 parts of ethylene glycol and 2-8 parts of glycerol. The natural, safe and environmentally friendly composition used in the white kraft paper coating of the present invention is an absolute green packaging when combined with paper, truly conforms to the national environmental strategy, conforms to the environmental standards of international trade, and expands the application scope of white kraft paper in packaging. The white kraft paper coating process technology of the present invention adopts a process of coating and then peeling off the film, and this innovative process makes the coating brighter and has better visual effects and commercial value.

Description

Technical Field

[0001] The invention relates to the technical field of packaging coatings, and in particular to a green, environment-friendly, moisture-proof and antibacterial white kraft paper coating and process technology. Background Art

[0002] With the growth of consumer demand and the continuous development of the logistics industry, packaging materials have become an indispensable part of modern life. There are many types of packaging materials, and different industries and scenarios require different packaging materials. Paper packaging materials are a common packaging material with the advantages of environmental protection, easy processing, and lightness. They are widely used in small daily necessities (such as socks, scarves, headwear, etc.), small cultural and creative products (such as various cards, stickers, paper-cuts, exquisite souvenirs, etc.), daily chemical products (such as eye patches, wrinkle patches, temporary skin care creams, etc.) and other industries.

[0003] White kraft paper is a special type of kraft paper, usually with a white appearance. Compared with traditional kraft paper, it is bleached or made of white pulp, with long fibers and higher strength, so the surface is bright white and usually smoother. It can be used for the above packaging to show its lightness, cleanliness and elegance. However, the biggest weakness of white kraft paper is that it is easily eroded by moisture, which in turn breeds mold and other bacteria, causing the contents to be contaminated and rotten. Therefore, it restricts the packaging application of food and medicine. Because these two types of materials need to be unaffected by the ambient temperature and humidity during a certain storage and transportation period, and not be eroded by moisture to breed mold, to ensure safety and perfect quality. Therefore, in order to change this fatal weakness of white kraft paper and improve the moisture resistance and antibacterial properties of white kraft paper, there are also some studies in the industry, such as coating a layer of synthetic resin coating on the surface of white kraft paper, or compounding with other plastic films, or using various mixed chemical additives to make coatings. Although these practices have improved the moisture permeability and antibacterial properties, they may pose safety risks to food, medicine or human health, pollute the environment, and form barriers to export trade because they contain substances such as synthetic plastics and chemical additives, solvents and additives.

[0004] Therefore, the present invention aims to provide a green and environmentally friendly moisture-proof and antibacterial white kraft paper coating, which is entirely composed of natural, safe and environmentally friendly substances and is an absolute green packaging when combined with paper. Summary of the invention

[0005] Based on the problems existing in the background technology, the present invention provides a green and environmentally friendly moisture-proof and antibacterial white kraft paper coating and process technology. The coating of the present invention not only meets the environmental standards of international trade, but also effectively protects the inner packaging. Moreover, it can be recycled after being discarded, without the need to mine new resources, which is in line with the country's carbon emissions. At the same time, it also brings considerable commercial value.

[0006] The present invention is implemented by the following technical solutions:

[0007] On the one hand, the present invention discloses a green and environmentally friendly moisture-proof and antibacterial white kraft paper coating, which comprises the following components in parts by weight: 5-15 parts of polyvinyl alcohol aqueous solution, 10-20 parts of carboxymethyl cellulose aqueous solution, 5-8 parts of chitosan aqueous solution, 3-8 parts of gelatin aqueous solution, 1-5 parts of emulsion wax, 2-8 parts of ethylene glycol and 2-8 parts of glycerol.

[0008] Furthermore, the concentration of the polyvinyl alcohol aqueous solution is 10%.

[0009] Furthermore, the concentration of the carboxymethyl cellulose aqueous solution is 8%.

[0010] Furthermore, the concentration of the chitosan aqueous solution is 8%; the chitosan aqueous solution also contains 2% acetic acid.

[0011] Furthermore, the concentration of the gelatin aqueous solution is 20%.

[0012] Furthermore, ethylene glycol can play a role in regulating the viscosity of the coating liquid and increasing the stability of each component in the entire system. Glycerol, as a plasticizer and solubilizer, can increase the plasticity and flexibility of the coating liquid, promote the fusion of the various components of the system, and facilitate the subsequent use of the coating liquid. The various components in the system can achieve better and more uniform mutual solubility under the action and plasticization of ethylene glycol and glycerol.

[0013] The second aspect of the present invention discloses a green and environmentally friendly process technology for moisture-proof and antibacterial white kraft paper coating, comprising the following steps:

[0014] (1) preparing a coating solution;

[0015] (2) Evenly apply the coating liquid on the white kraft paper with a scraper;

[0016] (3) After coating, a layer of PLA film is immediately applied on the coating;

[0017] (4) A rubber roller is used to roll the PLA film, and the white kraft paper is baked on a flat plate. After baking, the upper film is immediately peeled off and rewound to obtain a green and environmentally friendly white kraft paper coating that is moisture-proof and antibacterial.

[0018] Furthermore, the coating solution is prepared in step (1) by preparing a polyvinyl alcohol aqueous solution, a carboxymethyl cellulose aqueous solution, a chitosan aqueous solution and a gelatin aqueous solution; the polyvinyl alcohol aqueous solution, the carboxymethyl cellulose aqueous solution, the chitosan aqueous solution and the gelatin aqueous solution are uniformly mixed, emulsion wax, ethylene glycol and propylene glycol are added, and stirring is continued in a water bath at 70-80°C to obtain the coating solution.

[0019] Furthermore, the coating amount of the coating liquid in step (2) is 20-50 g / m2 .

[0020] Furthermore, in step (4), the roller rolling pressure is 4-5 kg.

[0021] Furthermore, in step (4), the temperature of baking the bottom of the white kraft paper on the flat plate is 60-70° C., and the residence time is 30-60 seconds.

[0022] Furthermore, in step (4), hot air can be blown under the plate.

[0023] Beneficial effects of the present invention:

[0024] (1) The white kraft paper with a green and environmentally friendly moisture-proof and antibacterial coating prepared by the present invention has significantly improved moisture-proof and antibacterial properties. Compared with ordinary white kraft paper, the moisture-proof property is improved by about 5 times, and the antibacterial and bactericidal properties are improved by more than 15 times.

[0025] (2) The polyvinyl alcohol, carboxymethyl cellulose, chitosan, gelatin and emulsion wax in the coating solution of the present invention can be better blended under the action and plasticization of ethylene glycol and propylene glycol, which is convenient for the subsequent coating steps.

[0026] (3) The green and environmentally friendly composition used in the white kraft paper coating of the present invention is an absolute green packaging when combined with paper, which truly complies with the national environmental strategy and the environmental standards of international trade. The raw materials for the coating in the present invention are widely available and are all environmentally friendly materials. The white kraft paper can be degraded and recycled after being discarded, which can protect the environment and reduce carbon emissions. The coating process of the present invention not only improves the strength of the white kraft paper, but also gives the white kraft paper moisture-proof and antibacterial and sterilization properties, greatly expanding the packaging range of the white kraft paper bags, making them light and beautiful, saving resources and reducing costs. The present invention provides a broader space and development prospects for white kraft paper as a green and low-cost packaging, and also lays a solid foundation for subsequent continuous research.

[0027] (4) The white kraft paper coating process of the present invention adopts a process of coating and then peeling off the film, so that the coating becomes bright and has better visual effect and value, thereby broadening the scope of use of white kraft paper and overcoming the barriers to import and export trade. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings are used to provide further explanation of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0029] Figure 1 This is a process flow chart of the green and environmentally friendly moisture-proof and antibacterial white kraft paper coating;

[0030] Figure 2This is a graph showing the moisture permeability of the green and environmentally friendly moisture-proof and antibacterial white kraft paper coating in Example 1;

[0031] Figure 3 This is the moisture permeability diagram of the untreated white kraft paper in Comparative Example 1. DETAILED DESCRIPTION

[0032] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments, but the protection scope of the present invention is not limited to the following embodiments.

[0033] Example 1

[0034] A green and environmentally friendly moisture-proof and antibacterial white kraft paper coating comprises the following steps:

[0035] (1) preparing a coating solution;

[0036] Prepare 10% polyvinyl alcohol aqueous solution, 8% carboxymethyl cellulose aqueous solution, 8% chitosan aqueous solution (containing 2% acetic acid) and 20% gelatin aqueous solution;

[0037] Mix 10g of polyvinyl alcohol aqueous solution, 15g of carboxymethyl cellulose aqueous solution, 5g of chitosan aqueous solution and 5g of gelatin aqueous solution, add 3g of emulsion wax, 5g of ethylene glycol and 5g of propylene glycol, and continue stirring in a water bath at 80°C to obtain a coating solution.

[0038] (2) Use a scraper to evenly apply the coating liquid on the white kraft paper, with a coating amount of 30g / m 2 ;

[0039] (3) After coating, a layer of PLA film is immediately applied on the coating;

[0040] (4) A rubber roller is used to roll the PLA film at a rolling pressure of 4 kg, and the white kraft paper underneath is baked on a flat plate at a baking temperature of 70°C for a residence time of 30 seconds. After the baking is completed, the upper film is immediately peeled off and rewound to obtain a green and environmentally friendly white kraft paper coating that is moisture-resistant and antibacterial.

[0041] Example 2

[0042] A green and environmentally friendly moisture-proof and antibacterial white kraft paper coating comprises the following steps:

[0043] (1) preparing a coating solution;

[0044] Prepare 10% polyvinyl alcohol aqueous solution, 8% carboxymethyl cellulose aqueous solution, 8% chitosan aqueous solution (containing 2% acetic acid) and 20% gelatin aqueous solution;

[0045] 8 g of polyvinyl alcohol aqueous solution, 16 g of carboxymethyl cellulose aqueous solution, 6 g of chitosan aqueous solution and 6 g of gelatin aqueous solution were mixed evenly, 2 g of emulsion wax, 5 g of ethylene glycol and 5 g of propylene glycol were added, and the mixture was stirred evenly in a water bath at 80°C to obtain a coating solution.

[0046] (2) Use a scraper to evenly apply the coating liquid on white kraft paper, with a coating amount of 25g / m 2 ;

[0047] (3) After coating, a layer of PLA film is immediately applied on the coating;

[0048] (4) A rubber roller is used to roll the PLA film at a rolling pressure of 4 kg, and the white kraft paper underneath is baked on a flat plate at a baking temperature of 70°C for a residence time of 30 seconds. After the baking is completed, the upper film is immediately peeled off and rewound to obtain a green and environmentally friendly white kraft paper coating that is moisture-resistant and antibacterial.

[0049] Example 3

[0050] A green and environmentally friendly moisture-proof and antibacterial white kraft paper coating comprises the following steps:

[0051] (1) preparing a coating solution;

[0052] Prepare 10% polyvinyl alcohol aqueous solution, 8% carboxymethyl cellulose aqueous solution, 8% chitosan aqueous solution (containing 2% acetic acid) and 20% gelatin aqueous solution;

[0053] Mix 10g of polyvinyl alcohol aqueous solution, 15g of carboxymethyl cellulose aqueous solution, 5g of chitosan aqueous solution and 3g of gelatin aqueous solution, add 3g of emulsion wax, 5g of ethylene glycol and 5g of propylene glycol, and continue stirring in a water bath at 80°C to obtain a coating solution.

[0054] The remaining steps are the same as in Example 1.

[0055] Example 4

[0056] A green and environmentally friendly moisture-proof and antibacterial white kraft paper coating comprises the following steps:

[0057] (1) preparing a coating solution;

[0058] Prepare 10% polyvinyl alcohol aqueous solution, 8% carboxymethyl cellulose aqueous solution, 8% chitosan aqueous solution (containing 2% acetic acid) and 20% gelatin aqueous solution;

[0059] Mix 10g of polyvinyl alcohol aqueous solution, 15g of carboxymethyl cellulose aqueous solution, 5g of chitosan aqueous solution and 4g of gelatin aqueous solution, add 3g of emulsion wax, 5g of ethylene glycol and 5g of propylene glycol, and continue stirring in a water bath at 80°C to obtain a coating solution.

[0060] The remaining steps are the same as in Example 1.

[0061] Comparative Example 1

[0062] The comparative example is white kraft paper without any treatment.

[0063] Comparative Example 2

[0064] A green and environmentally friendly moisture-proof and antibacterial white kraft paper coating comprises the following steps:

[0065] (1) preparing a coating solution;

[0066] Prepare 10% polyvinyl alcohol aqueous solution, 8% carboxymethyl cellulose aqueous solution, 8% chitosan aqueous solution (containing 2% acetic acid) and 20% gelatin aqueous solution;

[0067] Mix 10g of polyvinyl alcohol aqueous solution, 15g of carboxymethyl cellulose aqueous solution, 1g of chitosan aqueous solution and 5g of gelatin aqueous solution, add 3g of emulsion wax, 5g of ethylene glycol and 5g of propylene glycol, and continue stirring in a water bath at 80°C to obtain a coating solution.

[0068] The remaining steps are the same as in Example 1.

[0069] Comparative Example 3

[0070] A green and environmentally friendly moisture-proof and antibacterial white kraft paper coating comprises the following steps:

[0071] (1) preparing a coating solution;

[0072] Prepare 10% polyvinyl alcohol aqueous solution, 8% carboxymethyl cellulose aqueous solution, 8% chitosan aqueous solution (containing 2% acetic acid) and 20% gelatin aqueous solution;

[0073] Mix 10g of polyvinyl alcohol aqueous solution, 15g of carboxymethyl cellulose aqueous solution, 2g of chitosan aqueous solution and 5g of gelatin aqueous solution, add 3g of emulsion wax, 5g of ethylene glycol and 5g of propylene glycol, and continue stirring in a water bath at 80°C to obtain a coating solution.

[0074] The remaining steps are the same as in Example 1.

[0075] Comparative Example 4

[0076] A green and environmentally friendly moisture-proof and antibacterial white kraft paper coating comprises the following steps:

[0077] (1) preparing a coating solution;

[0078] Prepare 10% polyvinyl alcohol aqueous solution, 8% carboxymethyl cellulose aqueous solution, 8% chitosan aqueous solution (containing 2% acetic acid) and 20% gelatin aqueous solution;

[0079] Mix 10g of polyvinyl alcohol aqueous solution, 15g of carboxymethyl cellulose aqueous solution, 3g of chitosan aqueous solution and 5g of gelatin aqueous solution, add 3g of emulsion wax, 5g of ethylene glycol and 5g of propylene glycol, and continue stirring in a water bath at 80°C to obtain a coating solution.

[0080] The remaining steps are the same as in Example 1.

[0081] Comparative Example 5

[0082] A green and environmentally friendly moisture-proof and antibacterial white kraft paper coating comprises the following steps:

[0083] (1) preparing a coating solution;

[0084] Prepare 10% polyvinyl alcohol aqueous solution, 8% carboxymethyl cellulose aqueous solution, 8% chitosan aqueous solution (containing 2% acetic acid) and 20% gelatin aqueous solution;

[0085] Mix 10g of polyvinyl alcohol aqueous solution, 15g of carboxymethyl cellulose aqueous solution, 4g of chitosan aqueous solution and 5g of gelatin aqueous solution, add 3g of emulsion wax, 5g of ethylene glycol and 5g of propylene glycol, and continue stirring in a water bath at 80°C to obtain a coating solution.

[0086] The remaining steps are the same as in Example 1.

[0087] Comparative Example 6

[0088] A green and environmentally friendly moisture-proof and antibacterial white kraft paper coating comprises the following steps:

[0089] (1) preparing a coating solution;

[0090] Prepare 10% polyvinyl alcohol aqueous solution, 8% carboxymethyl cellulose aqueous solution, 8% chitosan aqueous solution (containing 2% acetic acid) and 20% gelatin aqueous solution;

[0091] Mix 10g of polyvinyl alcohol aqueous solution, 15g of carboxymethyl cellulose aqueous solution, 5g of chitosan aqueous solution and 1g of gelatin aqueous solution, add 3g of emulsion wax, 5g of ethylene glycol and 5g of propylene glycol, and continue stirring in a water bath at 80°C to obtain a coating solution.

[0092] The remaining steps are the same as in Example 1.

[0093] Comparative Example 7

[0094] A green and environmentally friendly moisture-proof and antibacterial white kraft paper coating comprises the following steps:

[0095] (1) preparing a coating solution;

[0096] Prepare 10% polyvinyl alcohol aqueous solution, 8% carboxymethyl cellulose aqueous solution, 8% chitosan aqueous solution (containing 2% acetic acid) and 20% gelatin aqueous solution;

[0097] Mix 10g of polyvinyl alcohol aqueous solution, 15g of carboxymethyl cellulose aqueous solution, 5g of chitosan aqueous solution and 2g of gelatin aqueous solution, add 3g of emulsion wax, 5g of ethylene glycol and 5g of propylene glycol, and continue stirring in a water bath at 80°C to obtain a coating solution.

[0098] The remaining steps are the same as in Example 1.

[0099] Comparative Example 8

[0100] A green and environmentally friendly moisture-proof and antibacterial white kraft paper coating comprises the following steps:

[0101] (1) preparing a coating solution;

[0102] Prepare 10% polyvinyl alcohol aqueous solution, 8% carboxymethyl cellulose aqueous solution, 8% chitosan aqueous solution (containing 2% acetic acid) and 20% gelatin aqueous solution;

[0103] Mix 10g of polyvinyl alcohol aqueous solution, 15g of carboxymethyl cellulose aqueous solution, 5g of chitosan aqueous solution and 1g of gelatin aqueous solution, add 3g of emulsion wax, 5g of ethylene glycol and 5g of propylene glycol, and continue stirring in a water bath at 80°C to obtain a coating solution.

[0104] (2) Use a scraper to evenly apply the coating liquid on the white kraft paper, with a coating amount of 30g / m 2 ;

[0105] (3) After the coating is completed, a layer of PLA film is not coated on the coating, and the bottom of the white kraft paper is directly baked on a flat plate. The baking temperature is 70°C and the residence time is 30s. After the baking is completed, the white kraft paper is rewound.

[0106] Comparative Example 9

[0107] A green and environmentally friendly moisture-proof and antibacterial white kraft paper coating comprises the following steps:

[0108] (1) preparing a coating solution;

[0109] Prepare 10% polyvinyl alcohol aqueous solution, 8% carboxymethyl cellulose aqueous solution, 8% chitosan aqueous solution (containing 2% acetic acid) and 20% gelatin aqueous solution;

[0110] Mix 10g of polyvinyl alcohol aqueous solution, 15g of carboxymethyl cellulose aqueous solution, 5g of chitosan aqueous solution and 2g of gelatin aqueous solution, add 3g of emulsion wax, 5g of ethylene glycol and 5g of propylene glycol, and continue stirring in a water bath at 80°C to obtain a coating solution.

[0111] (2) Use a scraper to evenly apply the coating liquid on the white kraft paper, with a coating amount of 30g / m 2 ;

[0112] (3) After the coating is completed, a layer of PLA film is not coated on the coating, and the bottom of the white kraft paper is directly baked on a flat plate. The baking temperature is 70°C and the residence time is 30s. After the baking is completed, the white kraft paper is rewound.

[0113] Comparative Example 10

[0114] A green and environmentally friendly moisture-proof and antibacterial white kraft paper coating comprises the following steps:

[0115] (1) preparing a coating solution;

[0116] Prepare 10% polyvinyl alcohol aqueous solution, 8% carboxymethyl cellulose aqueous solution, 8% chitosan aqueous solution (containing 2% acetic acid) and 20% gelatin aqueous solution;

[0117] Mix 10g of polyvinyl alcohol aqueous solution, 15g of carboxymethyl cellulose aqueous solution, 5g of chitosan aqueous solution and 3g of gelatin aqueous solution, add 3g of emulsion wax, 5g of ethylene glycol and 5g of propylene glycol, and continue stirring in a water bath at 80°C to obtain a coating solution.

[0118] (2) Use a scraper to evenly apply the coating liquid on the white kraft paper, with a coating amount of 30g / m 2 ;

[0119] (3) After the coating is completed, a layer of PLA film is not coated on the coating, and the bottom of the white kraft paper is directly baked on a flat plate. The baking temperature is 70°C and the residence time is 30s. After the baking is completed, the white kraft paper is rewound.

[0120] Comparative Example 11

[0121] A green and environmentally friendly moisture-proof and antibacterial white kraft paper coating comprises the following steps:

[0122] (1) preparing a coating solution;

[0123] Prepare 10% polyvinyl alcohol aqueous solution, 8% carboxymethyl cellulose aqueous solution, 8% chitosan aqueous solution (containing 2% acetic acid) and 20% gelatin aqueous solution;

[0124] Mix 10g of polyvinyl alcohol aqueous solution, 15g of carboxymethyl cellulose aqueous solution, 5g of chitosan aqueous solution and 4g of gelatin aqueous solution, add 3g of emulsion wax, 5g of ethylene glycol and 5g of propylene glycol, and continue stirring in a water bath at 80°C to obtain a coating solution.

[0125] (2) Use a scraper to evenly apply the coating liquid on the white kraft paper, with a coating amount of 30g / m 2 ;

[0126] (3) After the coating is completed, a layer of PLA film is not coated on the coating, and the bottom of the white kraft paper is directly baked on a flat plate. The baking temperature is 70°C and the residence time is 30s. After the baking is completed, the white kraft paper is rewound.

[0127] Comparative Example 12

[0128] A green and environmentally friendly moisture-proof and antibacterial white kraft paper coating comprises the following steps:

[0129] (1) preparing a coating solution;

[0130] Prepare 10% polyvinyl alcohol aqueous solution, 8% carboxymethyl cellulose aqueous solution, 8% chitosan aqueous solution (containing 2% acetic acid) and 20% gelatin aqueous solution;

[0131] Mix 10g of polyvinyl alcohol aqueous solution, 15g of carboxymethyl cellulose aqueous solution, 5g of chitosan aqueous solution and 5g of gelatin aqueous solution, add 3g of emulsion wax, 5g of ethylene glycol and 5g of propylene glycol, and continue stirring in a water bath at 80°C to obtain a coating solution.

[0132] (2) Use a scraper to evenly apply the coating liquid on the white kraft paper, with a coating amount of 30g / m 2 ;

[0133] (3) After the coating is completed, a layer of PLA film is not coated on the coating, and the bottom of the white kraft paper is directly baked on a flat plate. The baking temperature is 70°C and the residence time is 30s. After the baking is completed, the white kraft paper is rewound.

[0134] Test Example 1

[0135] Antibacterial test

[0136] According to the national standard GB15979-2002, the hygienic standard for disposable sanitary products, the coating surface was smeared and sampled. The test results are shown in Table 1.

[0137] Table 1

[0138] project Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 <![CDATA[Total number of colonies (CFU / cm 2 )]]> ＜10 ＜10 ＜10 ＜10 ＜10

[0139] It can be seen from the results in Table 1 that the coated kraft paper prepared by the method of the present invention meets the requirements of the national standard GB15979-2002.

[0140] The kraft paper prepared in Example 1 and Comparative Examples 2-5 was cut into 2 cm x 3 cm / pieces, and a bacterial suspension of the same concentration was added to the coating surface for 20 minutes before sampling (unsterilized); after sterilization, a bacterial suspension of the same concentration was added to the surface of the base paper without surface coating for 20 minutes before sampling (the edge of the coated paper, i.e., the uncoated part, was taken and cut into 2 cm x 3 cm / piece). The test results are shown in Table 2.

[0141] Table 2

[0142]

[0143] From the results in Table 2, it can be seen that as the amount of chitosan increases, the bactericidal performance of the coated white kraft paper also increases. When the amount of chitosan aqueous solution is 5g, its bactericidal performance is improved by 15 times compared with the amount of chitosan aqueous solution of 1g. From the results of Example 1, it can also be seen that the bactericidal performance of the coating using the formulation of the present invention is significantly improved by 12 times compared with the white kraft paper without any treatment.

[0144] Test Example 2

[0145] Water barrier properties

[0146] The water barrier properties of the white kraft paper in Example 1 and Comparative Example 1 were tested using a MOCON PERMATRAN water vapor transmission rate tester. The test results are as follows: Figure 2 and 3 shown.

[0147] The moisture permeability of the coated white kraft paper prepared in Example 1 is 146.4 g / (m2*day), and the moisture permeability of the untreated white kraft paper in Comparative Example 1 is 623.0 g / (m2*day). It can be seen that applying the coating of the present invention on white kraft paper can greatly improve the water-blocking performance of the white kraft paper.

[0148] Test Example 3

[0149] Coating gloss testing

[0150] According to the national standard GB / T 8941-2007, the specular gloss of paper and paperboard is measured and tested. The specific results are shown in Table 3.

[0151] Table 3

[0152]

[0153]

[0154] As can be seen from the results in Table 3, as the amount of gelatin aqueous solution in the coating increases, the glossiness of white kraft paper increases. When the amount of gelatin aqueous solution is greater than or equal to 3g, the later changes are not significant. In Comparative Example 8, the steps of coating a layer of PLA film on the surface of the coating and rolling with a rubber roller on the PLA film are omitted. The glossiness of the prepared white kraft paper is not significantly improved compared with the base paper in Comparative Example 1. Comparative Examples 9-12 increase the amount of gelatin aqueous solution on the basis of Comparative Example 8. It is found that with the increase in the amount of gelatin, the glossiness of white kraft paper is improved but not significant. The data in Table 2 fully show that the addition of gelatin can improve the glossiness of the coating, and the synergistic effect of coating and rolling after coating significantly improves the glossiness of white kraft paper, giving white kraft paper better visual aesthetics and improving the commercial value of white kraft paper, thereby broadening the scope of use of white kraft paper and overcoming barriers to import and export trade.

[0155] Finally, it should be noted that the above-mentioned embodiments only express several implementation methods of the present invention and are not intended to limit the invention. For those skilled in the art, any modification, equivalent replacement, improvement, etc. made without departing from the concept of the present invention should be included in the protection scope of the invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A green and environmentally friendly preparation process of a moisture-proof and antibacterial white kraft paper coating, characterized in that: The following steps are involved: (1) preparing a coating solution; (2) Use a scraper to evenly apply the coating liquid on the white kraft paper; (3) After coating is completed, a layer of PLA film is immediately applied on the coating; (4) Rolling the PLA film with a rubber roller, and baking the white kraft paper on a flat plate. After baking, the upper film is immediately peeled off and rewound to obtain a green and environmentally friendly white kraft paper coating that is moisture-proof and antibacterial. The coating solution in step (1) is composed of the following components in parts by weight: 5-15 parts of polyvinyl alcohol aqueous solution, 10-20 parts of carboxymethyl cellulose aqueous solution, 5-8 parts of chitosan aqueous solution, 3-8 parts of gelatin aqueous solution, 1-5 parts of emulsion wax, 2-8 parts of ethylene glycol and 2-8 parts of glycerol; The concentration of the polyvinyl alcohol aqueous solution is 10%; The concentration of the carboxymethyl cellulose aqueous solution is 8%; The concentration of the chitosan aqueous solution is 8%; the chitosan aqueous solution also contains 2% acetic acid; The concentration of the gelatin aqueous solution is 20%.

2. The preparation process according to claim 1, characterized in that: The coating solution is prepared in step (1) by preparing a polyvinyl alcohol aqueous solution, a carboxymethyl cellulose aqueous solution, a chitosan aqueous solution and a gelatin aqueous solution; the polyvinyl alcohol aqueous solution, the carboxymethyl cellulose aqueous solution, the chitosan aqueous solution and the gelatin aqueous solution are uniformly mixed, emulsion wax, ethylene glycol and propylene glycol are added, and the mixture is stirred uniformly in a water bath at 70-80° C. to obtain the coating solution.

3. The preparation process according to claim 1, characterized in that: The coating amount of the coating liquid in step (2) is 20-50g / m 2 .

4. The preparation process according to claim 1, characterized in that: In step (4), the roller rolling pressure is 4-5 kg.

5. The preparation process according to claim 1, characterized in that: In step (4), the temperature of baking the bottom of the white kraft paper on the flat plate is 60-70° C., and the residence time is 30 s-60 s.

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