Preparation method of in-situ lignin bonded kapok fiber-based high-strength paper

Abstract

The invention discloses a preparation method of in-situ lignin-bonded kapok fiber-based high-strength paper. The preparation method comprises the following steps: removing wax and partial lignin components on the surface of kapok fibers through an alkaline solution, and then washing the kapok fibers with deionized water; the preparation method comprises the following steps: dispersing kapok fibers in deionized water to obtain a kapok fiber dispersion solution, and preparing primary kapok fiber base paper through a wet papermaking technology; and carrying out hot pressing on the primary kapok fiber-based paper to obtain the kapok fiber-based high-strength paper. The technical process is simple and convenient, is green and environment-friendly, and does not need other chemical reagents as adhesives. The kapok fiber-based high-strength paper has application prospects in the fields of food packaging, space flight and aviation, medicine and health and the like.

Description

Technical Field

[0001] This invention relates to the field of paper processing technology, specifically to a method for preparing high-strength paper based on kapok fiber and bonded by in-situ lignin. Background Technology

[0002] High-strength paper, characterized by its high burst strength, tensile strength, and tear resistance, is widely used in packaging, construction, furniture, and aerospace industries. However, current high-strength paper manufacturing processes generally rely on the introduction of chemical additives such as fillers, reinforcing agents, and wet-strength agents. This not only significantly increases production costs but also potentially leads to a series of environmental problems, including resource consumption, environmental pollution, and health risks. Furthermore, the long fibers used as papermaking raw materials require specific processing techniques and increase the difficulty of papermaking, potentially causing problems such as fiber clogging of screens or entanglement in grinding discs. Therefore, exploring and implementing green and environmentally friendly manufacturing strategies to achieve low-cost production of high-strength paper has profound theoretical and practical significance for the sustainable development of the paper processing industry.

[0003] To prepare high-strength paper, CN202311512953.1 improved the mechanical properties of paper by loading a dialdehyde starch / PVA and waterborne polyurethane layer onto the base paper. However, its complex preparation process and the use of chemical reagents increased production costs. In contrast, lignin, a naturally occurring polymer, forms a robust network structure in plant cell walls by cross-linking cellulose and hemicellulose, acting as a structural adhesive. This makes it possible to mimic its structural adhesive properties during papermaking. Furthermore, kapok fiber, a natural cellulose fiber with a length of approximately 8-32 mm, has the potential to be used directly as a papermaking raw material. The application of kapok fiber can not only simplify the papermaking process and reduce the technical difficulty of papermaking, but also, due to its natural origin, help reduce dependence on chemical additives, thereby promoting the greening and sustainability of high-strength papermaking. Summary of the Invention

[0004] The technical problem to be solved by this invention is: how to improve the mechanical properties of high-strength paper while solving the cost and environmental problems caused by adding chemical reagents during the preparation process.

[0005] To address the above problems, this invention provides a method for preparing in-situ lignin-bonded high-strength kapok fiber-based paper, comprising the following steps:

[0006] Step 1): Remove the wax and some lignin components from the surface of the kapok fiber by passing it through an alkaline solution, and then wash the kapok fiber with deionized water until the pH value of the washing liquid reaches 7.

[0007] Step 2): Disperse the kapok fibers obtained in Step 1) in deionized water to obtain a kapok fiber dispersion solution, and prepare nascent kapok fiber base paper by wet papermaking technology;

[0008] Step 3): The nascent kapok fiber base paper is hot-pressed to obtain kapok fiber base high-strength paper.

[0009] Preferably, the kapok fibers in step 1) are mechanically cut using a fiber shredder before use.

[0010] More preferably, the fiber pulverizer has a rotation speed of 6000-20000 rpm and a processing time of 2-30 min.

[0011] Preferably, the alkaline solution in step 1) includes at least one of sodium hydroxide, potassium hydroxide, calcium hydroxide, and ammonium hydroxide, and the mass concentration of the alkaline solution is 2-30%; the treatment temperature of the alkaline solution is 30-99℃, and the treatment time is 1-60 min.

[0012] Preferably, in step 2), the kapok fibers are dispersed in deionized water using a disperser with a speed of 1000-3000 rpm and a dispersion time of 10-30 min.

[0013] Preferably, the basis weight of the kapok fiber base paper obtained in step 2) is 18-360 g / m³. 2 .

[0014] Preferably, the temperature of hot pressing in step 3) is 30-180℃ and the pressure is 1-30MPa.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0016] (1) This study uses pure cotton fiber as papermaking raw material to achieve low-cost, environmentally friendly and biodegradable high-strength paper preparation, avoiding the cost and environmental problems caused by the use of synthetic fibers in traditional methods;

[0017] (2) This method uses the endogenous lignin of kapok fiber as a natural binder, replacing the chemical curing agent in the traditional high-strength paper preparation process, which not only significantly reduces the cost but also improves the green and environmentally friendly nature of the process.

[0018] (3) This method is simple, convenient and easy to control. By precisely controlling the fiber weight, temperature and pressure parameters of hot pressing, it can realize the customized production of high-strength paper with different mechanical properties to meet diverse application needs. Attached Figure Description

[0019] Figure 1 This is a surface electron microscope image of the high-strength paper based on kapok fiber prepared in Example 1;

[0020] Figure 2 This is a surface electron microscope image of the high-strength paper based on kapok fiber prepared in Example 2;

[0021] Figure 3 This is a surface electron microscope image of the high-strength paper based on kapok fiber prepared in Example 3;

[0022] Figure 4 This is a surface electron microscope image of the high-strength paper based on kapok fiber prepared in Example 4. Detailed Implementation

[0023] To make the present invention more apparent and understandable, preferred embodiments are described in detail below with reference to the accompanying drawings.

[0024] Example 1

[0025] Step 1: Use a fiber shredder to mechanically cut the kapok fibers at a speed of 6000 rpm for 0 min;

[0026] Step 2: Treat the kapok fibers in a sodium hydroxide solution with a sodium hydroxide concentration of 20 wt%, a treatment temperature of 60°C, and a treatment time of 5 minutes. Afterward, wash the treated kapok fibers with deionized water until the pH of the washing liquid reaches 7.

[0027] Step 3: Disperse the alkali-treated kapok fibers obtained in Step 1 evenly in deionized water using a disperser at a speed of 4500 r / s for 30 min.

[0028] Step 4: Prepare nascent kapok fiber base paper from the kapok fiber aqueous dispersion obtained in Step 2 using wet papermaking technology. The kapok fiber basis weight is 180 g / m². 2 ;

[0029] Step 5: The nascent kapok fiber base paper obtained in Step 3 is hot-pressed at a pressure of 10 MPa and a temperature of 150°C to obtain high-strength kapok fiber base paper.

[0030] The prepared high-strength paper based on kapok fiber is constructed from a dense network of chemical bonds formed by the physical entanglement between fibers and the internal flow and penetration of lignin. It exhibits a tensile strength of 28.75 MPa and a Young's modulus of 42.58 MPa.

[0031] Example 2

[0032] Step 1: Use a fiber shredder to mechanically cut the kapok fibers at a speed of 6000 rpm for 0 min;

[0033] Step 2: Treat the kapok fibers in a sodium hydroxide solution with a sodium hydroxide concentration of 20 wt%, a treatment temperature of 60°C, and a treatment time of 10 min. Afterward, wash the treated kapok fibers with deionized water until the pH of the washing liquid reaches 7.

[0034] Step 3: Disperse the alkali-treated kapok fibers obtained in Step 1 evenly in deionized water using a disperser at a speed of 5000 r / s for 30 min.

[0035] Step 4: Prepare nascent kapok fiber base paper from the kapok fiber aqueous dispersion obtained in Step 2 using wet papermaking technology. The kapok fiber basis weight is 270 g / m². 2 ;

[0036] Step 5: The nascent kapok fiber base paper obtained in Step 3 is hot-pressed at a pressure of 5 MPa and a temperature of 150°C to obtain high-strength kapok fiber base paper.

[0037] The prepared high-strength paper based on kapok fiber is constructed from a dense network of chemical bonds formed by the physical entanglement between fibers and the internal flow and penetration of lignin. It exhibits a tensile strength of 14.87 MPa and a Young's modulus of 25.16 MPa.

[0038] Example 3

[0039] Step 1: Use a fiber shredder to mechanically cut the kapok fibers at a speed of 10,000 rpm for 10 minutes;

[0040] Step 2: Treat the kapok fibers in a sodium hydroxide solution with a sodium hydroxide concentration of 15 wt%, a treatment temperature of 70°C, and a treatment time of 5 minutes. Afterward, wash the treated kapok fibers with deionized water until the pH of the washing liquid reaches 7.

[0041] Step 3: Disperse the alkali-treated kapok fibers obtained in Step 1 evenly in deionized water using a disperser at a speed of 4500 r / s for 30 min.

[0042] Step 4: Prepare nascent kapok fiber base paper from the kapok fiber aqueous dispersion obtained in Step 2 using wet papermaking technology. The kapok fiber basis weight is 90 g / m². 2 ;

[0043] Step 5: The nascent kapok fiber base paper obtained in Step 3 is hot-pressed at a pressure of 10 MPa and a temperature of 120°C to obtain high-strength kapok fiber base paper.

[0044] The prepared high-strength paper based on kapok fiber is constructed from a dense network of chemical bonds formed by the physical entanglement between fibers and the internal flow and penetration of lignin. It has a breaking strength of 10.65 MPa and a Young's modulus of 41.89 MPa.

[0045] Example 4

[0046] Step 1: Use a fiber shredder to mechanically cut the kapok fibers at a speed of 10,000 rpm for 20 minutes;

[0047] Step 2: Treat the kapok fibers in a sodium hydroxide solution with a sodium hydroxide concentration of 20 wt%, a treatment temperature of 50°C, and a treatment time of 20 min. Afterward, wash the treated kapok fibers with deionized water until the pH of the washing liquid reaches 7.

[0048] Step 3: Disperse the alkali-treated kapok fibers obtained in Step 1 evenly in deionized water using a disperser at a speed of 4000 r / s for 15 min.

[0049] Step 4: Prepare nascent kapok fiber base paper from the kapok fiber aqueous dispersion obtained in Step 2 using wet papermaking technology. The kapok fiber basis weight is 450 g / m². 2 ;

[0050] Step 5: The nascent kapok fiber base paper obtained in Step 3 is hot-pressed at a pressure of 20 MPa and a temperature of 150°C to obtain high-strength kapok fiber base paper.

[0051] The prepared high-strength paper based on kapok fiber is constructed from a dense network of chemical bonds formed by the physical entanglement between fibers and the internal flow and penetration of lignin. It has a tensile strength of 69.00 MPa and a Young's modulus of 1163.55 MPa.

[0052] Analysis of Examples 1-4 shows that as the fiber basis weight, hot pressing temperature and hot pressing pressure increase, the breaking strength and Young's modulus of the kapok fiber-based high-strength paper will also increase.

Claims

1. A process for the preparation of in-situ lignin bonded kapok fiber based high strength paper, characterized by, The method comprises the following steps: Step 1): removing the wax and part of the lignin component on the surface of kapok fibers by an alkaline solution, and then washing the kapok fibers with deionized water until the pH value of the washing liquid reaches 7; Step 2): dispersing the kapok fibers obtained in step 1) in deionized water to obtain a kapok fiber dispersion solution, and preparing a primary kapok fiber-based paper by a wet laying technology; Step 3): obtaining a kapok fiber-based high-strength paper by hot pressing the primary kapok fiber-based paper.

2. The process for the production of in-situ lignin bonded kapok fiber based high strength paper as claimed in claim 1 wherein, Before the kapok fibers in step 1) are used, the fibers are mechanically cut by a fiber crusher.

3. The process for the production of in-situ lignin bonded kapok fiber based high strength paper as claimed in claim 2 wherein, The rotating speed of the fiber crusher is 6000-20000 rpm, and the processing time is 2-30 min.

4. The process for the production of in-situ lignin bonded kapok fiber based high strength paper as claimed in claim 1 wherein, The alkaline solution in step 1) comprises at least one of sodium hydroxide, potassium hydroxide, calcium hydroxide and ammonium hydroxide, and the mass concentration of the alkaline solution is 2-30%; the processing temperature of the alkaline solution is 30-99℃, and the processing time is 1-60 min.

5. The process for the production of in-situ lignin bonded kapok fiber based high strength paper as claimed in claim 1 wherein, The kapok fibers in step 2) are dispersed in deionized water by a disperser, and the rotating speed of the disperser is 1000-3000 rpm, and the dispersion time is 10-30 min.

6. The process for the production of in-situ lignin bonded kapok fiber based high strength paper as claimed in claim 1 wherein, The paper obtained in step 2) has a basis weight of 18-360 g / m 2 .

7. The process for the production of in-situ lignin bonded kapok fiber based high strength paper as claimed in claim 1 wherein, The temperature of hot pressing in step 3) is 30-180℃, and the pressure is 1-30 MPa.

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