Preparation method of waterproof bamboo fiber

Abstract

The invention relates to a waterproof bamboo fiber preparation method, and belongs to the technical field of paper waterproof materials, and the waterproof bamboo fiber preparation method comprises the following steps: S1, AKD wax sheet melting; s2, uniformly coating AKD on the pulp board; s3, performing water bath heating on the pulp board; s4, preparing the waterproof bamboo fibers. The AKD emulsion does not need to be prepared, the AKD wax sheet is directly used for curing and emulsifying, so that the AKD and the bamboo fibers are more stably combined, the obtained waterproof bamboo fibers are higher in waterproof performance, the emulsifying process is easy to control, the uniformity of pulp quality is ensured, the waterproof performance of paper can be effectively improved, and the method is particularly suitable for paper products with higher requirements on waterproof performance.

Description

Technical Field

[0001] The invention belongs to the technical field of paper waterproof materials, and particularly relates to a method for preparing waterproof bamboo fiber. Background Art

[0002] Paper waterproofing technology is one of the important directions to improve the performance of paper products, and is widely used in packaging, transportation, food, medical and other industries. The traditional preparation technology of waterproof bamboo fiber generally uses AKD (alkyl ketene dimer) emulsion for internal sizing to make the paper waterproof.

[0003] However, the traditional waterproof sizing method has some technical and process problems. For example, in the actual production process, the preparation of AKD emulsion requires mixing AKD wax flakes with water and emulsifiers, and forming a stable emulsion through emulsification. This process involves multiple steps and requires special emulsification equipment and control technology, which leads to cumbersome production processes and long production time, increases production costs, and requires high automation and energy efficiency of the production line. In addition, there is a certain amount of chemical consumption in the preparation process of AKD emulsion, and the operation process is complicated, which is prone to problems such as incomplete emulsification and poor emulsion stability. The stability of AKD emulsion is easily affected by external factors (such as temperature, pH value, etc.), and emulsion stratification or incomplete emulsification may occur, thereby affecting the sizing effect and reducing the performance of bamboo fiber paper. AKD emulsion can be stored at room temperature for 2 months, and it is not allowed to exceed 30°C or be frozen. Practice has shown that when the storage temperature exceeds 30°C or is frozen, the amount of AKD used is more than twice the normal amount. If diluted with water, it must be used up within 48 hours, otherwise AKD will hydrolyze and lose its sizing effect. This not only increases production costs, but may also affect the stability and consistency of waterproof performance. Since the sizing effect of the emulsion is affected by many factors, bamboo fiber paper produced by traditional methods may have unstable waterproof performance in actual applications, especially in environments with large changes in humidity and temperature, the waterproof effect is likely to decrease. In traditional waterproofing technology, paper often needs to go through a long maturation process after production. This process is to allow the waterproofing agent to fully penetrate and set to achieve the desired waterproofing effect. This not only increases the production cycle, but may also bring additional storage and management costs.

[0004] Therefore, how to simplify the production process, improve efficiency, and at the same time maintain or enhance the waterproof effect has become a technical problem that needs to be urgently solved in the current waterproof bamboo fiber. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for preparing waterproof bamboo fiber. The present invention does not need to prepare AKD emulsion, and directly uses AKD wax flakes through aging and emulsification to make the combination of AKD and bamboo fiber more stable. The obtained waterproof bamboo fiber has stronger waterproof performance, and the emulsification process is easy to control, ensuring the uniformity of slurry quality, and can effectively improve the waterproofness of paper. The method is particularly suitable for paper products with high requirements for waterproof performance.

[0006] The present invention solves the technical problem by the following technical solutions:

[0007] A method for preparing waterproof bamboo fiber, the steps of the preparation method are:

[0008] S1. Take an appropriate amount of AKD wax flakes and put them into a beaker. Place the beaker on a temperature-controlled heating plate and heat at a constant temperature of 60°C until the AKD wax flakes are completely melted into liquid;

[0009] S2, evenly coating the liquid AKD on the pulp board and forming a thin film on the surface of the pulp board;

[0010] S3, tear the pulp sheet of S2 into pieces and put it into a water bath for heating treatment, and continue stirring and heating at 60°C for 100 minutes;

[0011] S4. Add bamboo fiber to the solution of S3 to prepare bamboo fiber slurry. Put the slurry into a grinding and dispersing machine and stir it evenly at high speed for 30 minutes to make AKD and bamboo fiber fully dispersed and emulsified. Use a paper sheet former to make the emulsified slurry into sheets to obtain waterproof bamboo fiber.

[0012] Moreover, the pulp board in step S2 is a bamboo fiber pulp board with a beating degree of 12°SR-15°SR.

[0013] Moreover, the coating thickness in the step S2 is 20-50 microns.

[0014] Moreover, the rotation speed of the grinding and dispersing machine in the step S4 is 2000 r / min.

[0015] Moreover, in the step S3, the stirring rate during the heating process is 300-500 r / min.

[0016] Moreover, the mass fraction of bamboo fiber in the bamboo fiber slurry in step S4 is between 1% and 2%.

[0017] Moreover, in the step S4, the waterproof bamboo fiber is made into paper with a basis weight of 80 g / m 2 Copy.

[0018] The positive effects that the present invention can produce are:

[0019] 1. The waterproof cellulose of the present invention has significant waterproofness and does not require post-ripening: the Cobb value of the obtained paper is lower than that of the paper treated by the traditional sizing method, and the surface water contact angle is higher than that of the paper treated by the traditional sizing method. The waterproof performance can reach or even exceed the effect of the traditional waterproof method. And a more excellent waterproof effect can be achieved without post-ripening.

[0020] 2. The waterproof cellulose of the present invention has good storage and transportation stability: the traditional waterproof sizing method uses AKD emulsion as a sizing agent, and the sizing agent in the form of an emulsion is difficult to store for a long time and is prone to stratification or deterioration. The present invention adopts the method of directly adding AKD wax flakes. The AKD wax flakes have a longer storage period and better storage stability, are not easily affected by the environment and deteriorate, can be stored for a long time, and are convenient for use at any time during the production process, solving the inconvenience that AKD emulsion may cause during storage and transportation.

[0021] 3. The waterproof cellulose of the present invention has excellent production efficiency and operability: it can not only be added in the conventional paper production process, but also is easy to operate and has strong adaptability. Compared with the traditional sizing method, the present invention does not require emulsifiers and the cumbersome steps of preparing AKD emulsion, which greatly improves production efficiency and reduces waste in the production process.

[0022] 4. The preparation method of the present invention reduces environmental pollution: The waterproof sizing method adopted by the present invention has low volatile organic compound emissions, is environmentally friendly, and meets environmental protection requirements. Compared with the traditional waterproof treatment method containing organic solvents, the present invention is more environmentally friendly and reduces pollution to air and water. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of contact angle measurement of waterproof cellulose in the embodiments and comparative examples of the present invention. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below through specific examples. The following examples are only illustrative and not restrictive, and the protection scope of the present invention cannot be limited thereto.

[0025] A method for preparing waterproof bamboo fiber, the innovation of which lies in: the steps of the preparation method are:

[0026] S1. Take an appropriate amount of AKD wax flakes and put them into a beaker. Place the beaker on a temperature-controlled heating plate and heat at a constant temperature of 60°C until the AKD wax flakes are completely melted into liquid;

[0027] S2, evenly coating the liquid AKD on the pulp board and forming a thin film on the surface of the pulp board, the pulp board is a bamboo fiber pulp board with a beating degree of 12°SR-15°SR, and the coating thickness is 20-50 microns to ensure uniform coating and effectively improve the waterproof performance of bamboo fiber;

[0028] S3, tear the pulp sheet of S2 into pieces and put it into a water bath for heating treatment. Stir and heat continuously at 60°C for 100 minutes. The stirring rate during the heating process is 300-500r / min to ensure the uniformity of the solution.

[0029] S4, adding bamboo fiber to the solution of S3 to prepare bamboo fiber slurry, placing the slurry in a grinding and dispersing machine for high-speed shearing and uniform stirring for 30 minutes, the rotation speed of the grinding and dispersing machine is 2000r / min, so that AKD and bamboo fiber are fully dispersed and emulsified, and the emulsified slurry is used for sheeting by a paper sheet former to obtain waterproof bamboo fiber, the bamboo fiber mass fraction of the bamboo fiber slurry is between 1% and 2%, and the waterproof bamboo fiber is made into paper with a quantitative weight of 80g / m 2 Copy.

[0030] Example 1

[0031] A method for preparing waterproof bamboo fiber, the innovation of which lies in: the steps of the method are:

[0032] (1) AKD wax flakes accounting for 0.063% of the absolute dry pulp are placed in a beaker, which is consistent with the solid content in the 0.5% AKD emulsion, and are placed on a constant temperature heating plate at 60° C. and heated until the AKD wax flakes are completely melted and become liquid;

[0033] (2) Apply the melted liquid AKD evenly on the surface of the pulp board to ensure that the coating area is uniform.

[0034] (3) The pulp sheet coated with AKD wax flakes was torn into pieces, placed in a water bath, heated at 60°C and stirred for 100 min to ensure that AKD and bamboo fiber were fully reacted and matured;

[0035] (4) The bamboo fiber after the reaction was prepared into a 1% concentration slurry, and the slurry was placed in a grinding and dispersing machine, the speed was set to 2000r, and high-speed shearing was performed for 30 minutes until the AKD and the bamboo fiber were emulsified evenly;

[0036] (5) Using a paper sheet former to perform hand-forming to obtain paper raw materials, the paper is then placed in a vacuum drying oven for drying to ensure that the water is completely evaporated to obtain waterproof bamboo fiber.

[0037] Example 2

[0038] A method for preparing waterproof bamboo fiber, the innovation of which lies in: repeating the experiment according to the conditions and steps of Example 1, the difference being that the content of AKD wax flakes is adjusted to 0.125% of the absolute dry pulp, which is consistent with the solid content in 1% AKD emulsion.

[0039] Example 3

[0040] A method for preparing waterproof bamboo fiber, the innovation of which lies in: repeating the experiment according to the conditions and steps of Example 1, the difference being that the content of AKD wax flakes is adjusted to 0.188% of the absolute dry pulp, which is consistent with the solid content in the 1.5% AKD emulsion.

[0041] Example 4

[0042] A method for preparing waterproof bamboo fiber, the innovation of which lies in: repeating the experiment according to the conditions and steps of Example 1, the difference being that the content of AKD wax flakes is adjusted to 0.250% of the absolute dry pulp, which is consistent with the solid content in the 2% AKD emulsion.

[0043] Example 5

[0044] A method for preparing waterproof bamboo fiber, the innovation of which lies in: repeating the experiment according to the conditions and steps of Example 1, the difference being that the content of AKD wax flakes is adjusted to 0.313% of the absolute dry pulp, which is consistent with the solid content in the 2.5% AKD emulsion.

[0045] Example 6

[0046] A method for preparing waterproof bamboo fiber, the innovation of which lies in: repeating the experiment according to the conditions and steps of Example 1, the difference being that the content of AKD wax flakes is adjusted to 0.375% of the absolute dry pulp, which is consistent with the solid content in the 3% AKD emulsion.

[0047] Comparative Example 1

[0048] A method for preparing waterproof bamboo fiber, the innovation of which lies in: the steps of the method are:

[0049] (1) A finished AKD emulsion with a solid content of 12.5% ​​and a proportion of 0.5% of absolute dry pulp is added to the pulp for internal sizing. By controlling the amount of sizing, the AKD emulsion in the pulp is fully combined with the fiber to give the paper waterproof properties.

[0050] (2) Papermaking the sizing pulp to obtain waterproof bamboo fiber.

[0051] Comparative Example 2

[0052] A method for preparing waterproof bamboo fiber, the innovation of which lies in: repeating the experiment according to the conditions and steps of comparative example 1, the difference being that the content of AKD emulsion is adjusted to 1% of the absolute dry pulp.

[0053] Comparative Example 3

[0054] A method for preparing waterproof bamboo fiber, the innovation of which lies in: repeating the experiment according to the conditions and steps of comparative example 1, the difference being that the content of AKD emulsion is adjusted to 1.5% of the absolute dry pulp.

[0055] Comparative Example 4

[0056] A method for preparing waterproof bamboo fiber, the innovation of which lies in: repeating the experiment according to the conditions and steps of comparative example 1, the difference being that the content of AKD emulsion is adjusted to 2% of the absolute dry pulp.

[0057] Comparative Example 5

[0058] A method for preparing waterproof bamboo fiber, the innovation of which lies in: repeating the experiment according to the conditions and steps of comparative example 1, the difference being that the content of AKD emulsion is adjusted to 2.5% of the absolute dry pulp.

[0059] Comparative Example 6

[0060] A method for preparing waterproof bamboo fiber, the innovation of which lies in: repeating the experiment according to the conditions and steps of comparative example 1, the difference being that the content of AKD emulsion is adjusted to 3% of the absolute dry pulp.

[0061] The Cobb value of the waterproof bamboo fibers prepared in Examples 1 to 6 and Comparative Examples 1 to 6 was measured for 60 seconds. The test results are the average values ​​of 5 groups of data, as shown in Table 1.

[0062] Table 1 Sample Cobb value test results

[0063] Example 1 163.3 Comparative Example 1 165.8 Example 2 98.5 Comparative Example 2 105.3 Example 3 30.4 Comparative Example 3 38.2 Example 4 18.9 Comparative Example 4 23.2 Example 5 15.5 Comparative Example 5 18.4 Example 6 11.1 Comparative Example 6 12.6

[0064] Through the analysis of the Cobb value data in Table 1, it can be seen that the Cobb value of the waterproof bamboo fiber of Examples 1 to 6 can reach or even be slightly lower than that of the traditional waterproof technology. The lower the Cobb value, the less water the paper absorbs per unit time. Therefore, the new waterproof technology can significantly improve the waterproofness of the paper and prevent moisture from penetrating into the inside of the paper. When the same AKD solid content is used, the waterproof bamboo fiber prepared by the present invention can achieve the waterproof performance of the traditional waterproof method, or even exceed the traditional method. This shows that the new waterproof technology can save time and cost by eliminating the post-ripening time.

[0065] The contact angles of the waterproof bamboo fibers obtained in Examples 1 to 6 and Comparative Examples 1 to 6 were measured. Figure 1As shown, the data in the figure show that the contact angle of the waterproof cellulose paper of the present invention is greater than the contact angle of the paper treated with traditional waterproof technology, indicating that the angle formed by water droplets on the surface of the new bamboo fiber paper is larger. According to the contact angle theory, the larger the contact angle, the stronger the hydrophobicity of the paper and the better the waterproof performance. Therefore, the comparison results of the contact angles further support the advantage of the waterproof cellulose of the present invention in terms of waterproofness.

[0066] In summary, through comparative analysis of Cobb value and contact angle, it can be concluded that the waterproof cellulose of the present invention performs excellently in improving the waterproof performance of paper, can achieve or even exceed the waterproof effect of traditional technology, and can save post-ripening time.

[0067] AKD wax flakes themselves are insoluble in water, and they are solid at room temperature. However, through the aging and emulsification steps, AKD can effectively give paper waterproof properties. The main chemical component of AKD is the olefinic ketone dianhydride molecule. When the coated pulp board is torn into pieces and heated in a 60°C water bath, AKD begins to react chemically with water and the hydroxyl (-OH) in the bamboo fiber. The ketone group (C=O) reacts with the hydroxyl (-OH) in the fiber to form a chemical bond. As a result of this reaction, a stable chemical connection is formed between AKD and the fiber in the pulp. In this process, AKD forms a thin film on the fiber surface, and because the hydrophobicity of the reaction product is enhanced, the paper surface can effectively prevent water penetration. The formation of this film greatly improves the waterproof performance of the paper. In the process of slurry preparation, a grinding disperser is used for high-speed shearing, so that AKD can form a stable emulsified state in the bamboo fiber pulp. Through this process, AKD is emulsified with water and fiber to form fine AKD particles distributed in the slurry. Although AKD is insoluble in water, it can form tiny particles in the water phase, and these particles are tightly combined with fibers. The present invention does not need to use emulsifiers and other additives, saving the time and material costs of preparing AKD emulsions. In traditional waterproofing technology, paper often needs to go through a long maturation process after production. In contrast, the paper of the present invention can quickly show better waterproof performance without a long maturation time.

[0068] Although the embodiments and drawings of the present invention are disclosed for illustrative purposes, those skilled in the art will appreciate that various substitutions, changes and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims

1. A method for preparing waterproof bamboo fiber, characterized in that: The steps of the preparation method are: S1. Take an appropriate amount of AKD wax flakes and put them into a beaker. Place the beaker on a temperature-controlled heating plate and heat at a constant temperature of 60°C until the AKD wax flakes are completely melted into liquid; S2, evenly coating the liquid AKD on the pulp board and forming a thin film on the surface of the pulp board; S3, tear the pulp sheet of S2 into pieces and put it into a water bath for heating treatment, and continue stirring and heating at 60°C for 100 minutes; S4. Add bamboo fiber to the solution of S3 to prepare bamboo fiber slurry. Put the slurry into a grinding and dispersing machine and stir it evenly at high speed for 30 minutes to make AKD and bamboo fiber fully dispersed and emulsified. Use a paper sheet former to make the emulsified slurry into sheets to obtain waterproof bamboo fiber.

2. The method for preparing waterproof bamboo fiber according to claim 1, characterized in that: The pulp board in step S2 is a bamboo fiber pulp board with a beating degree of 12°SR-15°SR.

3. The method for preparing waterproof bamboo fiber according to claim 1, characterized in that: The coating thickness in step S2 is 20-50 microns to ensure uniform coating and effectively improve the waterproof performance of bamboo fiber.

4. The method for preparing waterproof bamboo fiber according to claim 1, characterized in that: The rotation speed of the grinding and dispersing machine in step S4 is 2000 r / min.

5. The method for preparing waterproof bamboo fiber according to claim 1, characterized in that: In the step S3, the stirring rate during the heating process is 300-500 r / min to ensure the uniformity of the solution.

6. The method for preparing waterproof bamboo fiber according to claim 1, characterized in that: In the step S4, the mass fraction of bamboo fiber in the bamboo fiber slurry is between 1% and 2%.

7. The method for preparing waterproof bamboo fiber according to claim 1, characterized in that: In step S4, the waterproof bamboo fiber is made into paper with a basis weight of 80 g / m 2 Copy.

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