Corrugated paper made from bamboo and methods for preparing corrugated paper using bamboo

Abstract

This invention discloses a corrugated paper made from bamboo and a method for preparing corrugated paper using bamboo. The corrugated paper is made from bamboo pulp and waste paper pulp, wherein the bamboo pulp accounts for at least 20%, and the bamboo pulp is produced by a steam explosion process involving physical treatment of bamboo. The method includes a crushing step, a steam explosion step, a pulping step, a beating step, and a papermaking step.

Description

Technical Field

[0001] This invention relates to the field of papermaking, and particularly to a corrugated paper made of bamboo and a method for preparing corrugated paper using bamboo. Background Technology

[0002] Corrugated paper is widely used in packaging to protect goods. It can generally be made from raw materials such as bamboo, reeds, wheat straw, cotton stalks, sugarcane bagasse, bamboo shoots, and wood.

[0003] Currently, the main processes for preparing pulp include chemical pulping and mechanical pulping. Chemical pulping primarily utilizes strong alkalis or sulfates, among other chemical agents, to penetrate the raw materials during high-temperature cooking. These chemicals react with the lignin in the raw materials, separating the lignin. However, this process generates large amounts of wastewater due to the large quantity of chemicals involved, polluting the environment and conflicting with increasingly stringent environmental protection requirements. Mechanical pulping reduces the amount of chemicals used through the shearing action of mechanical forces. However, this method fails to effectively disrupt the cell wall structure and lignin-containing structures at the microscopic level, potentially reducing fiber strength. Pure mechanical pulp is generally used as a filler, with its addition ratio typically not exceeding 10%. In addition, there are chemimechanical pulping and semi-chemical pulping methods, all of which require the addition of chemicals for treatment, and environmental pressures and drawbacks persist. Summary of the Invention

[0004] In order to solve the problems of chemical pollution caused by chemical pulping processes and poor paper strength of mechanical pulp in related technologies, this invention discloses a corrugated paper made of bamboo that does not contain any chemical additives and whose paper strength meets the standard requirements, as well as a method for preparing corrugated paper using bamboo.

[0005] The present invention provides a corrugated paper made of bamboo, the corrugated paper being made from bamboo pulp and waste paper pulp, wherein the bamboo pulp accounts for at least 20%, and the bamboo pulp is made from bamboo through a steam explosion process involving physical treatment.

[0006] Optionally, the proportion of bamboo pulp is 20% to 90%.

[0007] Optionally, the bamboo pulp is prepared by a purely physical process.

[0008] Optionally, the steam explosion process is as follows: bamboo blocks are fed into a steam explosion machine, saturated steam at 0.2 to 2.5 MPa is introduced into the steam explosion machine and the pressure is maintained for 1 to 20 minutes. Then, the pressure is released instantaneously so that the bamboo blocks are exploded in the steam explosion machine within 5 to 20 ms, and the material is instantly cooled to 40 to 80°C.

[0009] Optionally, after steam explosion, the average fiber length is 1200um-2500um.

[0010] Optionally, after the steam explosion, the material includes hemicellulose, cellulose, lignin, and lignin-modified rubbery substances.

[0011] Optionally, after the steam explosion process, the bamboo yield is 55% to 95%.

[0012] Optionally, the process of manufacturing the corrugated paper further includes:

[0013] Pulping step: The material after steam explosion is fed into a pulper to separate the steam-exploded bamboo fibers and refine the pulp into fine fibers.

[0014] Optionally, the process of manufacturing the corrugated paper also includes a pulping step: pulping the refined bamboo pulp and waste paper separately or mixed in a pulping machine, and then conveying them into a pulp tank.

[0015] Optionally, the process of manufacturing the corrugated paper also includes a papermaking step: papermaking of the pulped material.

[0016] Optionally, the steam explosion process, grinding step, and pulping step involve no chemical additives and are purely physical processes.

[0017] The present invention also provides a method for preparing corrugated paper using bamboo, comprising:

[0018] Crushing step: Crush the bamboo into bamboo blocks;

[0019] Steam explosion procedure: The bamboo block is fed into the steam explosion machine. Saturated steam at 0.2-2.5 MPa is introduced into the steam explosion machine and the pressure is maintained for 1-20 minutes. Then, the pressure is released instantaneously so that the bamboo block explodes in the steam explosion machine within 5-20 ms, and the material is instantly cooled to 40-80℃.

[0020] Pulping step: The material after steam explosion is fed into a pulper to separate the steam-exploded bamboo fibers and refine the pulp into fine fibers;

[0021] Pulping steps: The bamboo pulp after refining, with a bamboo pulp content of at least 20%, is pulped separately or mixed with waste paper in a pulping machine, and then sent to the pulp tank; and

[0022] Papermaking steps: The pulped material is then processed into paper.

[0023] The crushing step, the steam explosion step, the grinding step, and the pulping step are all physical processing steps.

[0024] Optionally, the proportion of bamboo pulp is 20% to 90%.

[0025] Optionally, the crushing step, the steam explosion step, the grinding step, and the pulping step are all purely physical processing steps.

[0026] Optionally, after the steam explosion step, the average fiber length is 1200um-2500um.

[0027] Optionally, after the steam explosion step, the material includes hemicellulose, cellulose, lignin, and a rubbery substance modified from lignin.

[0028] Optionally, after the steam explosion step, the bamboo yield is 55% to 95%.

[0029] The technical solutions provided by the embodiments disclosed in this invention may include the following beneficial effects:

[0030] This invention discloses another type of corrugated paper made from bamboo, wherein the corrugated paper is made from bamboo pulp and waste paper pulp, with the bamboo pulp accounting for at least 20%, and the bamboo pulp is produced by a steam explosion process involving physical treatment of bamboo. The corrugated paper disclosed in this invention increases the bamboo pulp ratio to 20%, reduces the proportion of waste paper pulp (which has higher costs), thereby lowering the production cost of corrugated paper, improving economic efficiency, and facilitating large-scale production and manufacturing. This steam explosion process is a purely physical treatment process, without the addition of any chemical agents, causing no pollution and meeting environmental protection requirements. Furthermore, after steam explosion, the lignin is partially removed or modified into a rubbery substance, making the exposed bamboo fibers easier to bond, thus improving the paper's strength.

[0031] This invention discloses a method for preparing corrugated paper using bamboo. The method includes a crushing step, a steam explosion step, a refining step, a pulping step, and a papermaking step. The crushing step involves crushing the bamboo into bamboo blocks. The steam explosion step involves feeding the bamboo blocks into a steam explosion machine, introducing saturated steam at 0.2–2.5 MPa, maintaining the pressure for 1–20 minutes, and then instantly releasing the pressure to cause the bamboo blocks to explode within 5–20 ms, instantly cooling the material to 40–80°C. The refining step involves feeding the steam-exploded material into a refining machine to separate the bamboo fibers and refine the pulp into finer fibers. The pulping step involves pulping the refined bamboo pulp (at least 20% bamboo pulp) separately or mixed with waste paper in a pulping machine, and then feeding it into a pulp tank. The papermaking step involves processing the pulped material into paper. The aforementioned crushing, steam explosion, grinding, and beating steps are all physical processing steps, without the addition of any chemical agents, resulting in no pollution and meeting environmental protection requirements. After steam explosion, some lignin is removed or modified into a rubbery substance, exposing bamboo fibers that are easier to bond, thereby improving paper strength. Furthermore, increasing the bamboo pulp ratio to over 20% helps reduce the production cost of corrugated paper, improving economic efficiency and facilitating large-scale production and manufacturing. The full utilization of bamboo, a fast-growing timber, also helps protect forest resources and increase the economic income of farmers in the region.

[0032] It should be understood that the above general description and the following detailed description are merely exemplary and do not limit the invention. Attached Figure Description

[0033] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0034] Figure 1 This is a flowchart of the method for preparing corrugated paper using bamboo disclosed in this invention. Detailed Implementation

[0035] To further illustrate the principles and structure of the present invention, the preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0036] As mentioned earlier, chemical pulping is highly polluting, while mechanical pulping cannot effectively separate lignin. With the development of science and technology, some have begun to explore steam explosion methods for pulp preparation. Steam explosion pulping uses steam to treat plant fiber raw materials with cellular structures. This involves using high-temperature, high-pressure steam to soften the lignin, reduce the lateral bonding strength of the fiber pulp, and cause the steam in the pores of the raw material to expand rapidly, resulting in an explosion. This allows the fibers to separate and disperse, partially stripping away the lignin and tearing the raw material into smaller fibers. However, these steam explosion pulping methods are mainly used for raw materials such as straw and wood. Since my country has the world's richest bamboo resources, the largest bamboo forest area, and the highest bamboo production, and bamboo has the advantage of faster growth compared to wood, and compared to other non-wood raw materials such as wheat straw and rice straw, bamboo has advantages such as longer fibers, better pulp properties, and no seasonality. Therefore, using bamboo for pulping can not only promote sustainable resource development but also enhance market competitiveness. However, due to the significant differences in anisotropy and structural strength characteristics of bamboo itself, including bamboo nodes and bamboo green, the processing is complex and the process parameters are difficult to determine. Therefore, the process of producing corrugated paper using steam explosion technology to blast bamboo without adding chemical agents has not yet been applied.

[0037] The inventors realized that by using a specific steam explosion method, lignin can be effectively separated or modified into a rubber-like substance while retaining relatively intact fibers. After multiple experiments, it was found that under this steam explosion method, the proportion of bamboo pulp in corrugated paper increased to 20% to 90%, which can greatly reduce the production cost of corrugated paper and has significant environmental benefits.

[0038] The method proposed by the inventor is as follows:

[0039] Combination Figure 1 As shown, the method for preparing corrugated paper using bamboo provided by the present invention includes:

[0040] S1, Crushing step: Crush the bamboo into bamboo blocks.

[0041] The bamboo material can be native bamboo harvested directly from the bamboo growing site, or it can be bamboo left over or discarded from the manufacture of other products, such as waste bamboo from the manufacture of container flooring.

[0042] Bamboo can be broken into bamboo blocks, which can be 2-5cm in length. Cutting bamboo into 2-5cm lengths helps to minimize damage to the fiber length of the bamboo and facilitates the separation of lignin, cellulose and hemicellulose by steam explosion.

[0043] S2, Steam Explosion Step: The bamboo block is fed into the steam explosion machine. Saturated steam at 0.2-2.5 MPa is introduced into the steam explosion machine and the pressure is maintained for 1-20 minutes. Then, the pressure is released instantaneously so that the bamboo block explodes in the steam explosion machine within 5-20 ms, and the material is instantly cooled to 40-80℃.

[0044] After bamboo blocks are fed into a sealed steam detonator, the pressure of the steam entering the detonator is controlled within the range of 0.2–2.5 MPa and maintained for 1–20 minutes, placing the bamboo blocks under high temperature, high pressure, and high humidity. The pressure is then rapidly released, causing the bamboo blocks to explode within 5–20 ms in the detonator. During the steam explosion, steam enters the fibrous raw material and penetrates into the pores and cell walls between the fibers, forming hydrogen bonds with some of the hydroxyl groups in cellulose. Under the combined action of steam and heat, cellulose begins to soften and degrade, low-molecular-weight substances begin to dissolve, and the bonds between fibers begin to weaken. After the pressure is released, the internal pressure of the bamboo cells is much greater than the external pressure. When this process occurs suddenly within a short time, the steam inside the cells cannot release from the pores in time, and the enormous pressure of the steam causes an explosion inside the cells. Under the action of high temperature and high pressure, the structure of cellulose, hemicellulose, and lignin in the fiber cells is destroyed, the hydrogen bonds between cellulose fibers are broken, and the bonds between fibers are reduced, causing cellulose, hemicellulose, and lignin to separate.

[0045] The blasting process is completed in an extremely short instant, effectively separating lignin between fibers while minimizing damage to cellulose and hemicellulose. During this instantaneous blasting, some lignin is released from the fibers, while a small portion is modified to form a rubbery substance with hemicellulose, which can then be used to make bamboo pulp together with cellulose.

[0046] No chemical agents were added during the steam explosion process; it was a purely physical process.

[0047] It should be noted that purely physical treatment refers to the treatment process without the addition of any chemical agents. It should also be emphasized that if a small amount of chemical agent is added during the treatment process to circumvent the technical solution of this invention, and this small amount of chemical agent has no effect on the actual treatment process and does not require special wastewater treatment, then it still falls under the category of purely physical treatment and is within the scope of protection disclosed in this invention.

[0048] After a steam explosion, the average length of the resulting fibers is 1200um-2500um. The average length of the raw bamboo fibers in three-year-old moso bamboo is around 2200um, so a steam explosion does not have a significant impact on the fiber length.

[0049] After the steam explosion, the bamboo yield was 55% to 95%, which is much higher than the yield of chemical pulping.

[0050] S3, Pulping Step: The material after steam explosion is fed into a pulper to separate the steam-exploded bamboo fibers and refine the pulp into fine fibers.

[0051] After a steam explosion, the lignin in the material is destroyed, but it still contains cellulose. A pulper is used to open and remove the lignin, exposing the cellulose and allowing the cellulose fibers to come into direct contact with each other and form hydroxyl bonds. Pulping machines include pulverizers, high-consistency mills, medium-consistency mills, and low-consistency mills. The steam-exploded bamboo fibers first enter the pulverizer for initial grinding, then pass through a high-consistency mill, or a high-consistency mill process with two different intervals, to open and remove the lignin in a high-concentration, high-temperature environment. Next, they enter the medium and low-consistency mills to remove more lignin, while simultaneously refining the pulp into finer fibers, resulting in roughly flocculent fibers.

[0052] S4, Pulping step: The bamboo pulp after grinding, with a bamboo pulp ratio of at least 20%, is pulped separately or mixed with waste paper in a pulping machine and then sent to the pulp tank.

[0053] The proportion of bamboo pulp added refers to the ratio of bamboo pulp to the total amount of bamboo pulp and waste paper pulp. For example, if the weight of bamboo pulp is 50 kg and the weight of waste paper pulp added is also 50 kg, then the proportion of bamboo pulp is 50%.

[0054] The bamboo pulp after refining can be directly fed into a pulper for beating, while waste paper is also pulped separately in the pulper. The bamboo pulp and waste paper pulp are then mixed and transported to a pulp tank, wherein the bamboo pulp accounts for at least 20% of the mixture. In one embodiment, the proportion of bamboo pulp ranges from 20% to 90%.

[0055] Alternatively, the bamboo pulp after refining is first mixed with waste paper before being pulped in a beater, wherein the mixing ratio is at least 20% bamboo pulp, and the mixture is then transported together to the pulp tank after pulping. In one embodiment, the proportion of bamboo pulp ranges from 20% to 90%.

[0056] The above steps S1-S4 do not involve the addition of any chemical agents. The entire process is a purely physical treatment process, which is pollution-free, very environmentally friendly, and meets the increasingly stringent environmental protection requirements of the country.

[0057] S5, Papermaking step: The pulped material is used for papermaking.

[0058] Corrugated paper products are formed by using a papermaking machine, followed by dehydration, sizing, and drying.

[0059] The present invention also provides a corrugated paper made of bamboo, which can be produced by the above steps S1-S5, that is, by a purely physical method without any chemical agents. The corrugated paper is made from bamboo pulp and waste paper pulp, wherein the bamboo pulp accounts for at least 20%, and the bamboo pulp is produced by a steam explosion process involving physical treatment of bamboo.

[0060] Bamboo pulp is prepared through a purely physical steam explosion process in step S2. Therefore, the bamboo pulp contains no chemical agents and is free from chemical pollution. After steam explosion, the average fiber length is 1200µm-2500µm. The materials include hemicellulose, cellulose, lignin, and a lignin-modified rubbery substance. Due to the modification of some lignin, the fiber yield is increased. In one embodiment, the fiber yield is 55%–95%, significantly higher than that of chemical pulping.

[0061] In one embodiment, the proportion of bamboo pulp is 20% to 90%. The proportion of bamboo pulp can reach up to 90%, which can greatly reduce the proportion of waste paper pulp added and significantly reduce production costs.

[0062] The fiber pulp of corrugated paper is made by the above-mentioned steam explosion process. During the steam explosion, the huge explosive energy can instantly kill all viruses, bacteria, and insect eggs, achieving the effect of disinfection and sterilization.

[0063] As can be seen from the above, the method of producing corrugated paper is not only environmentally friendly, but also significantly increases the proportion of bamboo pulp, thereby greatly reducing costs and improving economic benefits. It is conducive to large-scale manufacturing and production, and helps to promote the large-scale application of bamboo materials in my country, thus supporting the country's pro-agriculture policies through industry.

[0064] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. All equivalent structural changes made based on the description and drawings of the present invention are included within the scope of protection of the present invention.

Claims

1. A type of corrugated paper made from bamboo, characterized in that, The corrugated paper is made from bamboo pulp and waste paper pulp, with the bamboo pulp accounting for at least 20%, and the bamboo pulp is made from bamboo through a steam explosion process involving physical treatment. The corrugated paper is made by the following steps: Crushing step: Crush the bamboo into bamboo blocks; Steam explosion process: Bamboo blocks are fed into a steam explosion machine. Saturated steam at 0.2–2.5 MPa is introduced into the machine and maintained at pressure for 1–20 minutes. Then, the pressure is released instantaneously, causing the bamboo blocks to explode within 5–20 ms in the steam explosion machine. The material is also instantly cooled to 40–80°C. After the steam explosion process, the bamboo yield is 55%–95%. Pulping step: The material after steam explosion is fed into a pulper to separate the steam-exploded bamboo fibers and refine the pulp into fine fibers; Pulping steps: The bamboo pulp after grinding is pulped separately or mixed with waste paper in a pulping machine and then sent to the pulp tank; as well as Papermaking steps: The pulped material is then processed into paper. The above steps involve no chemical additives and are all purely physical processes.

2. The corrugated paper made of bamboo according to claim 1, characterized in that, The proportion of bamboo pulp is 20% to 90%.

3. The corrugated paper made of bamboo according to claim 1, characterized in that, After the steam explosion, the average fiber length is 1200μm-2500μm.

4. The corrugated paper made of bamboo according to claim 1, characterized in that, After the steam explosion, the material includes hemicellulose, cellulose, lignin, and a rubbery substance modified with lignin.

5. A method for preparing corrugated paper using bamboo, characterized in that, It consists of the following steps: Crushing step: Crush the bamboo into bamboo blocks; Steam explosion process: Bamboo blocks are fed into a steam explosion machine. Saturated steam at 0.2–2.5 MPa is introduced into the machine and maintained at pressure for 1–20 minutes. Then, the pressure is released instantaneously, causing the bamboo blocks to explode within 5–20 ms in the steam explosion machine. The material is also instantly cooled to 40–80°C. After the steam explosion process, the bamboo yield is 55%–95%. Pulping step: The material after steam explosion is fed into a pulper to separate the steam-exploded bamboo fibers and refine the pulp into fine fibers; Pulping steps: The bamboo pulp after refining, with a bamboo pulp content of at least 20%, is pulped separately or mixed with waste paper in a pulping machine, and then sent to the pulp tank; and Papermaking steps: The pulped material is then processed into paper. The crushing step, the steam explosion step, the pulping step, the beating step, and the papermaking step are all purely physical processes without the addition of any chemical agents.

6. The method for preparing corrugated paper using bamboo according to claim 5, characterized in that, The proportion of bamboo pulp is 20% to 90%.

7. The method for preparing corrugated paper using bamboo according to claim 5, characterized in that, After the steam explosion step, the average fiber length is 1200μm-2500μm.

8. The method for preparing corrugated paper using bamboo according to claim 5, characterized in that, Following the steam explosion step, the material comprises hemicellulose, cellulose, lignin, and a rubbery substance modified from lignin.

Images