Preparation method of degradable and transparent cellulose plastic with high toughness
By using cellulose oxidation modification and bentonite composite method to form brick-mud structure, the mechanical strength and transparency of cellulose plastic are significantly improved, which solves the shortcomings of cellulose plastic in terms of mechanical properties and biodegradability, and realizes the preparation of high-strength, tough and biodegradable cellulose plastic.
Patent Information
- Application Number
- CN202511504735.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-21
- Publication Date
- 2025-12-19
AI Technical Summary
Existing cellulose plastics suffer from brittleness and poor flexibility in terms of mechanical properties, making it difficult to meet the high requirements of applications. At the same time, traditional improvement methods reduce their biodegradability and environmental friendliness.
A "brick-and-mortar" structure is formed by cellulose oxidation modification, bentonite composite and water molecule induction, which improves the mechanical strength and transparency of cellulose plastics. Sodium periodate is used as a strong oxidant and nano-bentonite is used as a reinforcing agent. A dense structure is formed by hot pressing.
A high-strength, tough, biodegradable, and transparent cellulose plastic was prepared, with a mechanical strength of 75 MPa and a transparency of 85.5%. After 3 months in soil, the weight loss rate reached 90.1%, which can replace traditional petroleum-based plastics.
Smart Images
Figure CN121159902A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of plastics and relates to a method for preparing a cellulose plastic that is high in strength and toughness, biodegradable and transparent. Background Technology
[0002] Plastics are widely used in various fields of production and daily life due to their excellent properties such as light weight, durability, and low cost. However, most traditional plastics are derived from non-renewable petroleum resources and are extremely difficult to degrade in the natural environment, leading to an increasingly serious problem of "white pollution," which poses a long-term threat to the ecological environment and human health. Therefore, developing environmentally friendly plastics derived from renewable resources and capable of natural degradation after use has become an important research direction in the fields of materials science and sustainable development.
[0003] Cellulose is the most abundant natural polymer in the world, possessing outstanding advantages such as renewability, complete biodegradability, good biocompatibility, and low cost, making it one of the ideal candidate materials to replace traditional petroleum-based plastics. Currently, the main methods for preparing plastic polymer materials using cellulose as a raw material include: viscose preparation of adhesive fiber materials, cellulose-reinforced composite materials, and cellulose dissolution and regeneration membrane materials. However, viscose preparation of adhesive fiber materials suffers from long process flows and high energy consumption; cellulose-reinforced composite materials have limited cellulose content; and cellulose dissolution and regeneration membrane materials suffer from insufficient mechanical strength, especially high brittleness and poor flexibility, making it difficult to meet the application requirements of plastic products with high mechanical performance requirements (such as packaging materials and daily-use plastic parts). In summary, plastic materials with high cellulose content often have poor mechanical properties, while improving mechanical properties by compounding with other polymers reduces their biodegradability and environmental friendliness. Therefore, there is an urgent need to develop a new preparation method that can significantly improve the mechanical strength and overall performance of cellulose plastics while maintaining their high biodegradability and high bio-based content, thereby further promoting the industrial application of cellulose plastics and practicing the concept of green and low-carbon development. Summary of the Invention
[0004] Purpose of the invention: In order to solve the technical problems existing in the prior art, the present invention aims to provide a green, efficient, and scalable method for preparing cellulose plastics that are high in strength and toughness, biodegradable and transparent.
[0005] Technical solution: The preparation method of the high-strength, tough, biodegradable, and transparent cellulose plastic of the present invention includes the following steps: (1) Disperse cellulose in a solvent to obtain a cellulose dispersion; (2) Add a strong oxidant to the cellulose dispersion, mix and react, then add bentonite or organic bentonite, continue to disperse and mix, and filter and wash the resulting mixture to obtain a filter membrane. (3) After drying the filter membrane, immerse it in a solvent to obtain a wetted filter membrane, and then perform hot pressing to obtain cellulose plastic.
[0006] Further, in step (1), the mass concentration of the cellulose dispersion is 0.1-5 wt%; the solvent is water.
[0007] Further, in step (1), the cellulose is one or more of wood dissolving pulp, wood chemimechanical pulp, wood chemical pulp, bamboo dissolving pulp, bamboo chemimechanical pulp, bamboo chemical pulp, cotton, nanocellulose, microcrystalline cellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, or carboxymethylcellulose.
[0008] Further, in step (2), the strong oxidant is sodium periodate; the mass ratio of cellulose to strong oxidant is 1:1-3; the conditions for the mixed reaction are: stirring at 25-70°C for 5-24 h.
[0009] Further, in step (2), the amount of bentonite added is 2-15 wt% of the cellulose mass; the organic bentonite is prepared by reacting a long-chain quaternary ammonium salt on the surface of bentonite, and the long-chain quaternary ammonium salt is one or more of bis(octadecyl)dimethylammonium chloride, bis(hexadecyl)dimethylammonium chloride, or octadecyltrimethylammonium chloride; the organic bentonite contains 25-45 wt% of the long-chain quaternary ammonium salt.
[0010] Further, in step (2), the process of forming the filter membrane is as follows: the mixture is filtered on the filter membrane under a pressure of -0.2MPa to -0.1MPa for 2-5 minutes, wherein the mass concentration of the mixture is 0.1wt%-5wt%; and the thickness of the filter membrane is 1-5 mm.
[0011] Further, in step (3), the mass ratio of the filter membrane to the solvent is 1:0.5-3; the conditions for the hot pressing treatment are: temperature 70-140 ℃, pressure 2.0-8.0 MPa, and time 2-10 min.
[0012] Invention Principle: This invention utilizes cellulose oxidation modification, bentonite composite, and water molecule induction to form a "brick-and-mortar" structure in plastics. The bentonite lamellar structure acts as the "brick," the long cellulose chains act as the "mortar," and water molecules, acting as plasticizers, induce the cellulose chains to rearrange during reheat pressing, forming a dense structure that achieves high transparency in the plastic. This preparation method significantly improves the mechanical strength of cellulose plastics while increasing the preparation efficiency, reducing production costs, and further expanding the application potential of cellulose plastics in replacing traditional petroleum-based plastics.
[0013] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: (1) The preparation method of the high-strength, tough, degradable and transparent cellulose plastic described in the present invention is convenient and efficient. The cellulose plastic prepared can replace traditional petroleum-based plastics, thereby further improving the added value of cellulose and expanding its application range; (2) The cellulose plastic of the present invention has the characteristics of high transparency, high mechanical strength and degradability. Its mechanical strength is up to about 75 MPa. After being buried in the soil for 3 months, the weight loss rate is 90.1 wt%. The transmittance in the visible light region is more than 85.5%. It can be used as a green substitute for petroleum-based plastics. Attached Figure Description
[0014] Figure 1 The mechanical properties of the cellulose plastic prepared in Example 1 are shown in the figure. Figure 2 This is an optical transparency diagram of the cellulose plastic prepared in Example 1. Detailed Implementation
[0015] The present invention will now be further described in conjunction with specific embodiments and accompanying drawings.
[0016] The raw materials and reagents used in the following examples and comparative examples are all commercially available.
[0017] Example 1: Preparation of cellulose plastics using wood dissolving pulp. The preparation method includes the following steps: (1) Soak the wood dissolving pulp in deionized water at 1 wt%, and disperse it in a homogenizer for 40 min to obtain a cellulose dispersion; (2) Add the cellulose dispersion to a round-bottom flask, add sodium periodate at a cellulose:sodium periodate mass ratio of 1:1.5, and stir at 50 °C for 12 h. Then add 5 wt% of nano-bentonite by cellulose mass to the reaction solution and continue to disperse for 20 min using a homogenizer to obtain a mixture with a mass concentration of 1 wt%. Filter the mixture on a filter membrane under a pressure of -0.1 MPa for 2 minutes and wash with deionized water to obtain a filter membrane with a thickness of 3 mm. (3) After drying the filter membrane, the filter membrane is re-wetted at a mass ratio of 1:1.5 (filter membrane: water). Finally, the wetted filter membrane is hot-pressed at 110 °C and 5.0 MPa for 7 min to obtain cellulose plastic.
[0018] Figure 1 This is the mechanical tensile stress-strain curve of the cellulose plastic in Example 1. Figure 1 The cellulose plastic exhibits excellent mechanical properties, with a mechanical strength of up to approximately 75 MPa and a mechanical toughness of 1.23 MJ / m. 3 This indicates the excellent mechanical properties of cellulose plastics.
[0019] Figure 2 The image shown is an optical photograph of the cellulose plastic in Example 1. Figure 2 Cellulose plastics exhibit excellent optical transparency; patterns beneath a 0.15 mm thick cellulose plastic film can be clearly observed, demonstrating the high transparency of cellulose plastics.
[0020] Example 2: Preparation of cellulose plastics using wood pulp. The preparation method includes the following steps: (1) The wood pulp was soaked in deionized water at 0.1 wt%, and dispersed in a homogenizer for 40 min to obtain a cellulose dispersion; (2) Add the cellulose dispersion to a round-bottom flask, add sodium periodate at a cellulose:sodium periodate mass ratio of 1:1.5, and stir at 70 °C for 6 h. Then add 2 wt% of nano-bentonite by cellulose mass to the reaction solution and continue to disperse for 20 min using a homogenizer to obtain a mixture with a mass concentration of 0.1 wt%. Filter the mixture on a filter membrane under a pressure of -0.1 MPa for 2 minutes and wash with deionized water to obtain a filter membrane with a thickness of 1.0 mm. (3) After drying the filter membrane, the filter membrane is re-wetted at a mass ratio of 1:1 (filter membrane: water). Finally, the wetted filter membrane is hot-pressed at 90°C and 5.0 MPa for 7 min to obtain cellulose plastic.
[0021] Example 3: Preparation of cellulose plastics using wood chemical pulp. The preparation method includes the following steps: (1) Soak the wood chemical pulp in deionized water at 2 wt%, and disperse it in a homogenizer for 40 min to obtain a cellulose dispersion; (3) Add the cellulose dispersion to a round-bottom flask, add sodium periodate at a cellulose:sodium periodate mass ratio of 1:1.5, and stir the reaction at 25 °C for 24 h. Then add 7.5 wt% of nano-bentonite of cellulose to the reaction solution and continue to disperse it for 20 min using a homogenizer to obtain a mixture with a mass concentration of 2 wt%. Filter the mixture on a filter membrane under a pressure of -0.1 MPa for 2 minutes and wash it with deionized water to obtain a filter membrane with a thickness of 3.2 mm. (4) After drying the filter membrane, the filter membrane is re-wetted at a mass ratio of 1:2 (filter membrane: water). Finally, the wetted filter membrane is hot-pressed at 110°C and 4.0 MPa for 7 min to obtain cellulose plastic.
[0022] Example 4: Preparation of cellulose plastics using bamboo dissolving pulp. The preparation method includes the following steps: (1) Soak bamboo dissolving pulp in deionized water at 3 wt%, and disperse it in a homogenizer for 60 min to obtain cellulose dispersion; (2) Add the cellulose dispersion to a round-bottom flask, add sodium periodate at a cellulose:sodium periodate mass ratio of 1:2, and stir at 55 °C for 12 h. Then add 10 wt% of nano-bentonite by cellulose mass to the reaction solution and continue to disperse using a homogenizer for 20 min to obtain a mixture with a mass concentration of 3.3 wt%. Filter the mixture on a filter membrane under a pressure of -0.1 MPa for 2 minutes and wash with deionized water to obtain a filter membrane with a thickness of 3.7 mm. (3) After drying the filter membrane, the filter membrane is re-wetted at a mass ratio of 1:1.5 (filter membrane: water). Finally, the wetted filter membrane is hot-pressed at 90°C and 2.5 MPa for 7 min to obtain cellulose plastic.
[0023] Example 5: Preparation of cellulose plastics using microcrystalline cellulose. The preparation method includes the following steps: (1) Microcrystalline cellulose was soaked in deionized water at 4 wt% and dispersed in a homogenizer for 60 min to obtain a cellulose dispersion; (2) Add the cellulose dispersion to a round-bottom flask, add sodium periodate at a cellulose:sodium periodate mass ratio of 1:2.5, and stir at 40 °C for 12 h. Then add 15 wt% of nano-bentonite by cellulose mass to the reaction solution and continue to disperse for 20 min using a homogenizer to obtain a mixture with a mass concentration of 4.6 wt%. Filter the mixture on a filter membrane under a pressure of -0.1 MPa for 2 minutes and wash with deionized water to obtain a filter membrane with a thickness of 4.3 mm. (3) After drying the filter membrane, the filter membrane is re-wetted at a mass ratio of 1:2.5 (filter membrane: water). Finally, the wetted filter membrane is hot-pressed at 100 °C and 3.0 MPa for 7 min to obtain cellulose plastic.
[0024] Example 6: The difference from Example 1 is that in step (2), organic bentonite is used, which is prepared by reacting octadecyltrimethylammonium chloride on the surface of bentonite. It is a material that is purchased directly, with a purity specification of 25-30wt.% containing trimethylstearyl ammonium, product number: N477269, brand: Aladdin.
[0025] Example 7: The difference from Example 1 is that in step (2), organic bentonite is used, which is prepared by reacting the bentonite surface with dioctadecyl / hexadecyl dimethyl ammonium chloride. It is a material that is purchased directly. The purity specification is: containing 35-45wt.% dimethyl dialkyl (C14-C18) amine. The product number is N477270 and the brand is Aladdin.
[0026] The bentonite is a dimethyldialkyl (C14-C18)amine modified nano-bentonite.
[0027] Comparative Example 1: The difference from Example 1 is that nano-bentonite is not added in step (2).
[0028] Comparative Example 2: The difference from Example 1 is that the amount of nano-bentonite used in step (2) is 40 wt% of cellulose.
[0029] Comparative Example 3: The difference from Example 1 is that water molecule induction is not used in step (3): After drying the filter membrane, it is directly hot-pressed at 110 °C and 5.0 MPa for 7 min to obtain cellulose plastic.
[0030] The cellulose plastics prepared in Examples 1-7 and Comparative Examples 1-3 were subjected to performance tests, and the results are shown in Table 1 below. As can be seen from Table 1, the cellulose plastics prepared in Examples 1-7 all exhibit excellent mechanical properties, degradation properties, and transparency. However, the cellulose plastics prepared in Examples 6-7, due to the presence of amino groups in the modified bentonite, react with the aldehyde groups of oxidized cellulose, resulting in a slight yellowing of the samples. In Comparative Example 1, the lack of bentonite prevented the cellulose plastic from achieving a brick-and-mortar structure, and also resulted in poor mechanical properties. In Comparative Example 2, the excessive amount of bentonite caused aggregation and stress concentration, leading to poor performance, and the high content also resulted in opacity. In Comparative Example 3, the anhydrous molecule-induced material was opaque, non-uniform, and had poor performance.
[0031] Table 1 shows the performance test results of the cellulose plastics prepared in Examples 1-7 and Comparative Examples 1-3.
[0032]
Claims
1. A method for preparing a high-strength, tough, biodegradable, and transparent cellulose plastic, characterized in that, Includes the following steps: (1) Disperse cellulose in a solvent to obtain a cellulose dispersion; (2) Add a strong oxidant to the cellulose dispersion, mix and react, then add bentonite or organic bentonite, continue to disperse and mix, and filter and wash the resulting mixture to obtain a filter membrane. (3) After drying the filter membrane, immerse it in a solvent to obtain a wetted filter membrane, and then perform hot pressing to obtain cellulose plastic.
2. The preparation method according to claim 1, characterized in that, In step (1), the mass concentration of the cellulose dispersion is 0.1-5 wt%; the solvent is water.
3. The preparation method according to claim 1, characterized in that, In step (1), the cellulose is one or more of wood dissolving pulp, wood chemimechanical pulp, wood chemical pulp, bamboo dissolving pulp, bamboo chemimechanical pulp, bamboo chemical pulp, cotton, nanocellulose, microcrystalline cellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, or carboxymethylcellulose.
4. The preparation method according to claim 1, characterized in that, In step (2), the strong oxidant is sodium periodate; the mass ratio of cellulose to strong oxidant is 1:1-3.
5. The preparation method according to claim 1, characterized in that, In step (2), the conditions for the mixing reaction are: stirring at 25-70°C for 5-24 h.
6. The preparation method according to claim 1, characterized in that, In step (2), the amount of bentonite added is 2-15 wt% of the mass of cellulose.
7. The preparation method according to claim 1, characterized in that, In step (2), the organic bentonite is prepared by reacting a long-chain quaternary ammonium salt on the surface of bentonite. The long-chain quaternary ammonium salt is one or more of bis(octadecyldimethylammonium chloride), bis(hexadecyldimethylammonium chloride), or octadecyltrimethylammonium chloride.
8. The preparation method according to claim 1, characterized in that, In step (2), the process of forming the filter membrane is as follows: the mixture is filtered on the filter membrane under a pressure of -0.2MPa to -0.1MPa for 2-5 minutes, wherein the mass concentration of the mixture is 0.1wt%-5wt%; and the thickness of the filter membrane is 1-5 mm.
9. The preparation method according to claim 1, characterized in that, In step (3), the mass ratio of the filter membrane to the solvent is 1:0.5-3.
10. The preparation method according to claim 1, characterized in that, In step (3), the hot pressing conditions are: temperature 70-140 ℃, pressure 2.0-8.0 MPa, and time 2-10 min.