Moisture-proof and water-resistant translucent paper and preparation method and application thereof

Abstract

The application provides a moisture-proof and water-resistant translucent paper and a preparation method and application thereof, and relates to the field of paper processing. The moisture-proof and water-resistant translucent paper comprises a translucent base paper and a first water-proof layer and a second water-proof layer formed on the surface of the translucent base paper in sequence. The coating material for forming the first water-proof layer comprises the following raw materials in parts by weight: modified starch 0.5-5.0 parts, sodium alginate 0.5-5.0 parts, chitosan 0.5-5.0 parts, nano-cellulose 0.5-5.0 parts, polyvinyl alcohol 0.5-5.0 parts and water 100 parts. The coating material for forming the second water-proof layer comprises the following raw materials in parts by weight: ethyl cellulose 0.5-5.0 parts and alcohol 100 parts. The raw materials are all degradable substances, which replace the film coating and internal sizing from the source, and solve the problem of waste paper recycling difficulty. The raw materials are all modified products of natural substances, and are high in safety. The double-layer coating structure greatly improves the moisture-proof and water-resistant performance of the translucent paper.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of paper processing, in particular to a moisture-proof and water-resistant translucent paper and a preparation method and application thereof. BACKGROUND

[0002] Packaging materials play an important role in the entire packaging industry. With the development of economy, the demand for green packaging materials is also increasing. There are many types of packaging materials with different properties. Among them, plastics are more commonly used in the packaging field due to their lighter weight, lower cost and easy processing. Since plastics are difficult to degrade in nature and can migrate toxic substances to the surface of the packaged material during use, the use of green packaging materials instead of plastics and other non-degradable materials is increasingly valued.

[0003] Paper packaging materials are derived from wood, green and environmentally friendly, and are easily degradable and recyclable, having great development potential. Translucent paper has a high transparency of 70-80%, and is mainly used for the outer packaging and inner lining materials of precision instruments, instrument parts, silk fabrics, medical supplies, candies, tobacco and alcohol, cakes and pastries, and other commodities. Although translucent paper has certain moisture-proof properties, it is afraid of water and will lose its original strength, wrinkle, break and other problems once it is soaked in water, which can easily cause damage to the packaged material.

[0004] Currently, there are mainly the following ways to improve the water and oil resistance of paper: first, using film coating, wax coating or aluminum plating on the surface of the paper to achieve water and oil resistance; second, using in- pulp sizing during papermaking to add sizing agents such as alkyl ketene dimer (AKD) to form a hydrophobic film on the outer layer of the paper fibers, thereby obtaining certain hydrophobic properties of the paper made; third, coating a water and oil repellent agent on the surface of the base paper, the hydrophilic groups in the carbon chain of the oil repellent agent combine with the hydroxyl groups on the surface of the paper fibers, and the hydrophobic groups are oriented outward to form an oil-proof film, forming a low-surface-energy barrier, so that the paper can effectively resist oil and water penetration. Currently, fluorine-containing and silicon-containing oil repellents are more commonly used, in addition to which new types of oil repellents such as chitosan-based oil repellents are also used.

[0005] The above methods can improve the water and oil resistance of paper to some extent, but for food packaging paper such as translucent paper, film coating, wax coating and sizing will introduce corresponding substances, making it difficult to recycle waste paper; aluminum plating and other methods directly affect the translucency of the paper and cannot be applied to translucent paper; fluorine-containing and silicon-containing oil repellents will come into direct contact with food, posing a safety hazard; chitosan-based new oil repellents are safer, but they have the disadvantage of insufficient water and oil resistance.

[0006] Therefore, how to provide a moisture-proof and water-resistant translucent paper which can not affect waste paper recycling, paper translucency, safety and excellent water resistance at the same time has become a problem to be solved by those skilled in the art. SUMMARY

[0007] Therefore, the technical problem to be solved by the present application is to overcome the defects of the prior art method for improving the water and oil resistance of paper, such as difficulty in waste paper recycling, affecting the translucency of paper, poor safety, and insufficient water resistance, thereby providing a new moisture-proof and water-resistant translucent paper and a preparation method and application thereof.

[0008] To achieve the above-mentioned object, the present application provides the following technical solutions.

[0009] In a first aspect, the present application provides a moisture-proof and water-resistant translucent paper, comprising a translucent base paper and a first water-resistant layer and a second water-resistant layer formed on the surface of the translucent base paper in sequence,

[0010] The coating forming the first water-resistant layer comprises the following raw materials by weight: modified starch 0.5-5.0 parts, sodium alginate 0.5-5.0 parts, chitosan 0.5-5.0 parts, nanocellulose 0.5-5.0 parts, polyvinyl alcohol 0.5-5.0 parts, and water 100 parts;

[0011] The coating forming the second water-resistant layer comprises the following raw materials by weight: ethyl cellulose 0.5-5.0 parts, and alcohol 100 parts.

[0012] Further, the coating forming the first water-resistant layer comprises the following raw materials by weight: modified starch 4.0-5.0 parts, sodium alginate 0.5-1.0 parts, chitosan 4.0-5.0 parts, nanocellulose 4.0-5.0 parts, polyvinyl alcohol 4.0-5.0 parts, and water 100 parts;

[0013] The coating forming the second water-resistant layer comprises the following raw materials by weight: ethyl cellulose 4.0-5.0 parts, and alcohol 100 parts.

[0014] Further, the coating amount of the first water-resistant layer is 1%-15% of the weight of the base paper; and the coating amount of the second water-resistant layer is 0.1%-5% of the weight of the base paper.

[0015] Further, the coating amount of the first water-resistant layer is 7%-9% of the weight of the base paper; and the coating amount of the second water-resistant layer is 1%-2% of the weight of the base paper.

[0016] Further, the coating amount of the first water-resistant layer is 7.8%-8.5% of the weight of the base paper; and the coating amount of the second water-resistant layer is 1.9%-2.0% of the weight of the base paper.

[0017] Further, the volume fraction of the alcohol is 95%.

[0018] Further, the basis weight of the translucent base paper is 50-220 g / m 2 .

[0019] Further, the basis weight of the translucent base paper is 100 g / m 2 .

[0020] Further, the first waterproof layer and the second waterproof layer are coated on one side or both sides of the translucent base paper.

[0021] In a second aspect, the application provides a method for preparing the moisture-proof and water-proof translucent paper, comprising the following steps:

[0022] (1) taking modified starch, sodium alginate, chitosan, nanocellulose, polyvinyl alcohol and water in proportion, mixing uniformly to obtain a first waterproof coating;

[0023] (2) taking ethyl cellulose and alcohol in proportion, mixing uniformly to obtain a second waterproof coating;

[0024] (3) taking a translucent base paper, coating the first waterproof coating on the surface of the translucent base paper to form a first waterproof layer, and coating the second waterproof coating on the surface of the first waterproof layer to form a second waterproof layer.

[0025] Further, in step (3), the method for coating the first waterproof coating or the second waterproof coating comprises at least one of the following processes: gravure printing, letterpress printing, metering rod coating, air knife coating.

[0026] Further, in step (3), the first waterproof coating or the second waterproof coating is coated by gravure printing process, and the process conditions are as follows: speed of 50-200 m / min, oven temperature of 50-110℃.

[0027] Further, in step (3), the first waterproof coating is coated by gravure printing process, and the process conditions are as follows: speed of 80 m / min, oven temperature of 90℃.

[0028] Further, in step (3), the second waterproof coating is coated by gravure printing process, and the process conditions are as follows: speed of 80 m / min, oven temperature of 70℃.

[0029] In a third aspect, the application provides the moisture-proof and water-proof translucent paper or the moisture-proof and water-proof translucent paper obtained by the preparation method as a packaging paper or a lining material.

[0030] The technical scheme of the application has the following advantages:

[0031] The moisture-proof and water-resistant translucent paper provided by the application comprises a translucent base paper and a first water-proof layer and a second water-proof layer formed on the surface of the translucent base paper in sequence, first, the raw materials for forming the first water-proof layer and the second water-proof layer are all degradable substances, which replace the film coating and the internal sizing from the source, and solve the problems such as the difficulty in waste paper recycling; second, all the raw materials are modified products of natural substances (modified starch, sodium alginate, chitosan, nanocellulose, polyvinyl alcohol and ethyl cellulose), which are high in safety and do not harm the environment and human bodies; third, the two layers of coating formed by the compatibility of the raw materials are high in transparency and do not affect the translucency of the paper, and can be used for coating treatment of the translucent paper; and finally, the double-layer coating structure designed by the application greatly improves the moisture-proof and water-resistant performance of the translucent paper, and can produce good social and economic benefits.

[0032] It should be noted that the double-coating structure provided by the application is not simply the superposition of the water-proof coating, but is specially designed and considered. The inventors found in the experiment that the ethyl cellulose coating has good water-proof effect, but when it is applied to the base paper of the translucent paper, the combination with the base paper is not good, and obvious folds are easily generated in the using process, causing the coating to fail; the coating formed by the compounding of the modified starch, sodium alginate, chitosan, nanocellulose and polyvinyl alcohol has good film forming effect and high combination degree with the base paper, and is not easy to generate folds, but the coating formed by the compounding coating still has certain water-proof effect, and still has certain hygroscopicity due to the hydroxyl groups in the modified starch, chitosan and polyvinyl alcohol, which causes the water-proof performance to decrease in the using process; the inventors accidentally found that when the second water-proof coating containing ethyl cellulose is coated on the surface of the first water-proof coating formed by the compounding coating, the problems existing in the single coating are overcome, the combination between the first water-proof coating and the second water-proof coating is good, the problem of obvious folds generated in the direct coating of the ethyl cellulose coating is solved after the first water-proof coating is formed on the surface of the translucent base paper and the second water-proof coating is formed on the surface of the first water-proof coating, and the setting of the second water-proof coating also effectively improves the problem of poor water-proof effect of the first water-proof coating in the using process, the double coatings cooperate with each other to achieve excellent moisture-proof and water-resistant effect, and the effect can be maintained in the using process and is not easy to fail.

[0033] The first waterproof coating can play a key role in combination because in the aqueous solution of the first waterproof coating, the hydroxyl groups between several components in the raw materials interact to form hydrogen bonds, electrostatic forces and other cross-linking effects, thereby changing the molecular conformation and spatial structure, increasing the molecular weight, improving the viscosity and stability, in addition, sodium alginate can also provide additional anions to promote the adsorption and coagulation of several components in the raw materials, and enhance the gelation and gelation capacity, the compatibility of each component makes the coating film-forming and binding well, especially the first waterproof coating obtained by compounding modified starch, sodium alginate, chitosan, nanocellulose and polyvinyl alcohol has more prominent effect. DETAILED DESCRIPTION

[0034] The following examples are provided to better further understand the present application and are not limited to the best mode, and do not limit the content and scope of protection of the present application, and any person under the inspiration of the present application or the combination of the present application with other prior art features, any product same or similar to the present application falls within the scope of protection of the present application.

[0035] Raw material information used in the examples:

[0036] Modified starch: purchased from Guangxi Mingyang, viscosity 8~15 mPa·s (6%, 55℃), whiteness ≥88%.

[0037] Sodium alginate: purchased from Nanshan Biology, 1% aqueous solution pH value is 6-8, viscosity 500~800 mPa·s.

[0038] Chitosan: purchased from Hehai Biology, degree of deacetylation ≥90%, viscosity 20~800 mPa·s, particle size ≥80 mesh.

[0039] Nanocellulose: purchased from Aikema Chemical Industry, average particle size: width 4~5 nm wide, length 50~500 nm, solid content 6%.

[0040] Polyvinyl alcohol: purchased from Chuanwei Chemical Industry, alcoholysis degree ≥98%, viscosity 20~30 mPa·s.

[0041] Ethyl cellulose: purchased from Liming Chemical Industry, ethoxyl content ≥45~48%, solubility ≥99%, viscosity 40~50 mPa·s.

[0042] Semi-transparent base paper: take 500 kg of coniferous pulp, 100 kg of broadleaf pulp, produce semi-transparent base paper according to papermaking process, control the basis weight of semi-transparent paper on the equipment to 100 g / m 2 .

[0043] The specific experimental steps or conditions are not indicated in the examples, and the operation or conditions can be carried out according to the conventional experimental steps described in the literature in the art. The raw materials or instruments used are conventional products that can be obtained by purchase, including but not limited to the raw materials or instruments used in the examples of the present application.

[0044] Example 1

[0045] The present example provides a preparation method of a moisture-proof and water-resistant translucent paper, and the steps are as follows:

[0046] (1) Add 100 kg of water to a container, and add 0.5 kg of sodium alginate under stirring conditions. After stirring uniformly, add 5.0 kg of modified starch, and gelatinize at 90°C. After gelatinization is completed, add 4.0 kg of chitosan, 4.0 kg of nanocellulose, and 5.0 kg of polyvinyl alcohol, and stir uniformly to obtain a first waterproof coating;

[0047] (2) Add 100 kg of 95% alcohol to a container, and add 5.0 kg of ethyl cellulose under stirring conditions. After stirring uniformly, a second waterproof coating is obtained;

[0048] (3) Take a translucent base paper, and use intaglio printing process to coat the first waterproof coating on the surface of the translucent base paper, with a coating amount of 8.0% of the mass of the base paper, a vehicle speed of 80 m / min, and an oven temperature of 90°C, to form a first waterproof layer. The second waterproof coating is coated on the surface of the first waterproof layer using intaglio printing process, with a coating amount of 2.0% of the mass of the base paper, a vehicle speed of 80 m / min, and an oven temperature of 70°C, to form a second waterproof layer, and complete the double-sided coating.

[0049] Example 2

[0050] The present example provides a preparation method of a moisture-proof and water-resistant translucent paper, and the steps are as follows:

[0051] (1) Add 100 kg of water to a container, and add 1.0 kg of sodium alginate under stirring conditions. After stirring uniformly, add 4.0 kg of modified starch, and gelatinize at 90°C. After gelatinization is completed, add 5.0 kg of chitosan, 5.0 kg of nanocellulose, and 4.0 kg of polyvinyl alcohol, and stir uniformly to obtain a first waterproof coating;

[0052] (2) Add 100 kg of 95% alcohol to a container, and add 4.0 kg of ethyl cellulose under stirring conditions. After stirring uniformly, a second waterproof coating is obtained;

[0053] (3) Take the translucent base paper, adopt the gravure printing process to coat the first waterproof coating on the surface of the translucent base paper, the coating amount is 7.8% of the mass of the base paper, the vehicle speed is 80 m / min, the oven temperature is 90℃, the first waterproof layer is formed, the gravure printing process is adopted to coat the second waterproof coating on the surface of the first waterproof layer, the coating amount is 1.9% of the mass of the base paper, the vehicle speed is 80 m / min, the oven temperature is 70℃, the second waterproof layer is formed, and the double-sided coating is completed.

[0054] Example 3

[0055] The embodiment provides a preparation method of a moisture-proof and water-resistant translucent paper, and the steps are as follows:

[0056] (1) 100 kg of water is added to a container, 1.0 kg of sodium alginate is added under stirring conditions, 5.0 kg of modified starch is added after stirring uniformly, and the temperature is increased to 90℃ for gelatinization, 5.0 kg of chitosan, 5.0 kg of nanocellulose and 5.0 kg of polyvinyl alcohol are added after the gelatinization is completed, and stirring is uniform, to obtain a first waterproof coating;

[0057] (2) 100 kg of 95% alcohol is added to a container, 5.0 kg of ethyl cellulose is added under stirring conditions, and stirring is uniform to obtain a second waterproof coating;

[0058] (3) Take the translucent base paper, adopt the gravure printing process to coat the first waterproof coating on the surface of the translucent base paper, the coating amount is 8.5% of the mass of the base paper, the vehicle speed is 80 m / min, the oven temperature is 90℃, the first waterproof layer is formed, the gravure printing process is adopted to coat the second waterproof coating on the surface of the first waterproof layer, the coating amount is 2.0% of the mass of the base paper, the vehicle speed is 80 m / min, the oven temperature is 70℃, the second waterproof layer is formed, and the double-sided coating is completed.

[0059] Comparative Example 1

[0060] The comparative example provides a preparation method of a moisture-proof and water-resistant translucent paper, and the steps are as follows:

[0061] (1) 100 kg of water is added to a container, 1.0 kg of sodium alginate is added under stirring conditions, 10.0 kg of modified starch is added after stirring uniformly, and the temperature is increased to 90℃ for gelatinization, 10.0 kg of nanocellulose is added after the gelatinization is completed, and stirring is uniform to obtain a first waterproof coating;

[0062] (2) 100 kg of 95% alcohol is added to a container, 5.0 kg of ethyl cellulose is added under stirring conditions, and stirring is uniform to obtain a second waterproof coating;

[0063] (3) Take the translucent base paper, adopt the gravure printing process to coat the first waterproof coating on the surface of the translucent base paper, the coating amount is 8.5% of the mass of the base paper, the vehicle speed is 80 m / min, the oven temperature is 90℃, the first waterproof layer is formed, adopt the gravure printing process to coat the second waterproof coating on the surface of the first waterproof layer, the coating amount is 2.0% of the mass of the base paper, the vehicle speed is 80 m / min, the oven temperature is 70℃, the second waterproof layer is formed, and the double-sided coating is completed.

[0064] Comparative Example 2

[0065] The present comparative example provides a preparation method of a moisture-proof and water-resistant translucent paper, and the steps are as follows:

[0066] (1) Add water 100 kg in a container, add sodium alginate 1.0 kg under stirring condition, add modified starch 10.0 kg after stirring uniformly, gelatinize by increasing the temperature to 90℃, add polyvinyl alcohol 10.0 kg after the gelatinization is completed, stir uniformly, and the first waterproof coating is obtained;

[0067] (2) Add 95% alcohol 100 kg in a container, add ethyl cellulose 5.0 kg under stirring condition, stir uniformly, and the second waterproof coating is obtained;

[0068] (3) Take the translucent base paper, adopt the gravure printing process to coat the first waterproof coating on the surface of the translucent base paper, the coating amount is 8.5% of the mass of the base paper, the vehicle speed is 80 m / min, the oven temperature is 90℃, the first waterproof layer is formed, adopt the gravure printing process to coat the second waterproof coating on the surface of the first waterproof layer, the coating amount is 2.0% of the mass of the base paper, the vehicle speed is 80 m / min, the oven temperature is 70℃, the second waterproof layer is formed, and the double-sided coating is completed.

[0069] Comparative Example 3

[0070] The present comparative example provides a preparation method of a moisture-proof and water-resistant translucent paper, and the steps are as follows:

[0071] (1) Add water 100 kg in a container, add sodium alginate 1.0 kg under stirring condition, add modified starch 5.0 kg after stirring uniformly, gelatinize by increasing the temperature to 90℃, add chitosan 5.0 kg, nano-cellulose 5.0 kg, and polyvinyl alcohol 5.0 kg after the gelatinization is completed, stir uniformly, and the waterproof coating is obtained;

[0072] (2) Take the translucent base paper, adopt the gravure printing process to coat the first waterproof coating on the surface of the translucent base paper, the coating amount is 8.5% of the mass of the base paper, the vehicle speed is 80 m / min, the oven temperature is 90℃, the waterproof layer is formed, and the double-sided coating is completed.

[0073] Comparative Example 4

[0074] The present comparative example provides a preparation method of a moisture-proof and water-resistant translucent paper, and the steps are as follows:

[0075] (1) Add 100 kg of 95% alcohol to a container, and add 5.0 kg of ethyl cellulose under stirring condition, and stir uniformly to obtain a first water-resistant coating;

[0076] (2) Add 100 kg of water to a container, and add 1.0 kg of sodium alginate under stirring condition, and then add 5.0 kg of modified starch after stirring uniformly, and gelatinize by heating to 90°C, and then add 5.0 kg of chitosan, 5.0 kg of nano-cellulose and 5.0 kg of polyvinyl alcohol, and stir uniformly to obtain a second water-resistant coating;

[0077] (3) Take the translucent base paper, and coat the first water-resistant coating on the surface of the translucent base paper by using the gravure printing process, and the coating amount is 2.0% of the mass of the base paper, the vehicle speed is 80 m / min, and the oven temperature is 70°C to form a first water-resistant layer, and coat the second water-resistant coating on the surface of the first water-resistant layer by using the gravure printing process, and the coating amount is 8.5% of the mass of the base paper, the vehicle speed is 80 m / min, and the oven temperature is 90°C to form a second water-resistant layer, and complete the double-sided coating.

[0078] Experimental example

[0079] The moisture-proof and water-resistant translucent papers obtained by the examples and the comparative example are tested for performance, and the test methods of the indexes and the obtained test results are shown in Table 1.

[0080] Table 1 Performance indexes of the moisture-proof and water-resistant translucent paper

[0081]

[0082] From Table 1, it can be seen that the moisture-proof and water-resistant performance of the moisture-proof and water-resistant translucent paper prepared in Example 3 is the best, the transparency and tensile strength decrease slightly, the thickness increases slightly, which does not affect the normal use of the translucent paper; under the condition of ensuring the total amount of the coating in Example 3, the moisture-proof and water-resistant performance is reduced after the two components in the first waterproof coating are omitted (Comparative Example 1 and Comparative Example 2), which proves that the specific several raw materials in the first waterproof coating realize good synergistic effect in the moisture-proof and water-resistant performance; compared with Example 3, Comparative Example 3 only coats the first waterproof layer, the dosage decreases, the moisture-proof and water-resistant performance decreases, and the other performances change slightly, which proves that setting the second waterproof layer on the surface of the first waterproof layer can effectively improve the moisture-proof and water-resistant performance of the first waterproof layer; compared with Example 3, the order of the two layers in Comparative Example 4 is interchanged, the moisture-proof and water-resistant performance decreases, and the other performances change slightly, which proves that the waterproof layer prepared from modified starch, sodium alginate, chitosan, nanocellulose and polyvinyl alcohol has better combination performance with the translucent base paper than the waterproof layer prepared from ethyl cellulose and alcohol, and forms good combination with the translucent base paper and the outermost waterproof layer, and the waterproof layer prepared from ethyl cellulose and alcohol has better waterproof effect as the outermost coating.

[0083] Obviously, the above examples are only examples for clearly illustrating but not limiting the embodiments. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. All the embodiments do not need to be exhausted here. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A moisture resistant, water repellant, translucent paper, characterized in that, The moisture-proof and water-proof translucent paper comprises a translucent base paper and a first water-proof layer and a second water-proof layer formed on the surface of the translucent base paper in sequence, The coating forming the first water-proof layer comprises the following raw materials by weight: modified starch 4.0-5.0 parts, sodium alginate 0.5-1.0 parts, chitosan 4.0-5.0 parts, nano-cellulose 4.0-5.0 parts, polyvinyl alcohol 4.0-5.0 parts, and water 100 parts; The coating forming the second water-proof layer comprises the following raw materials by weight: ethyl cellulose 4.0-5.0 parts, and alcohol 100 parts, The coating amount of the first water-proof layer is 7-9% of the weight of the base paper, and the coating amount of the second water-proof layer is 1-2% of the weight of the base paper.

2. The moisture resistant, water repellant, translucent paper of claim 1, wherein, The volume fraction of the alcohol is 95%.

3. The moisture resistant, water repellant, translucent paper of claim 1, wherein, The basis weight of the translucent base paper is 50 to 220 g / m 2 .

4. The moisture resistant, water repellant, translucent paper of claim 3, wherein, The basis weight of the translucent base paper is 100 g / m 2 .

5. The moisture resistant, water repellant, translucent paper of claim 1, wherein, The first water-proof layer and the second water-proof layer are coated on one side or both sides of the translucent base paper.

6. The method of making a moisture resistant, water repellant, translucent paper according to any one of claims 1 to 5, characterized in that, The method comprises the following steps: (1) taking modified starch, sodium alginate, chitosan, nano-cellulose, polyvinyl alcohol and water in proportion, mixing uniformly to obtain a first water-proof coating; (2) taking ethyl cellulose and alcohol in proportion, mixing uniformly to obtain a second water-proof coating; (3) taking a translucent base paper, coating the first water-proof coating on the surface of the translucent base paper to form a first water-proof layer, and coating the second water-proof coating on the surface of the first water-proof layer to form a second water-proof layer.

7. The method of claim 6, wherein the moisture resistant, water repellant, translucent paper is prepared by the steps of: In step (3), the method for coating the first water-proof coating or the second water-proof coating comprises at least one of the following processes: gravure printing, letterpress printing, metering rod coating, and air knife coating.

8. Use of the moisture-proof and water-proof translucent paper according to any one of claims 1-5 or the moisture-proof and water-proof translucent paper obtained by the preparation method of claims 6 or 7 as a wrapping paper or a lining material.

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