Recycling method of recycled paper-plastic compound bag

Abstract

The invention relates to the field of paper-plastic compound bags, in particular to a cyclic utilization method of recycled paper-plastic compound bags, which comprises the following steps: screening raw materials, performing primary treatment on the raw materials, performing cyclic treatment on the raw materials, performing reinforced treatment on the raw materials, and performing cyclic utilization, and screening the long and short fibers. The paper pulp of the waste recycled paper is subjected to reinforcing treatment, specifically, cellulase is added to modify secondary fibers, paper fiber combination is enhanced through polyhydroxyalkanoate, the strength of the paper is improved, meanwhile, long and short fibers are differentiated and utilized, and the long and short fibers are prepared into the inner layer and the outer layer of the bag body respectively; and through different characteristics of the long and short fibers and the paper strength, the overall strength of the regenerated bag is improved, and the recovery efficiency of the regenerated paper is effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of paper-plastic composite bags, and in particular to a recycling method for recycled paper-plastic composite bags. Background Art

[0002] Recycled paper-plastic composite bags are bags made of recycled paper and plastic. They are usually made of three layers of materials: the outer layer is recycled paper, the middle layer is a moisture-proof and waterproof plastic film, and the inner layer is a soft plastic film or recycled paper.

[0003] At present, traditional recycled paper-plastic composite bags are mostly made of recycled paper for the inner and outer layers of waste paper. Although the recycled paper that has been specially treated still has high strength and wear resistance, the strength of the recycled paper cannot be guaranteed after multiple recycling, and the recycling process is relatively cumbersome, time-consuming and labor-intensive. As a result, most recycled paper-plastic composite bags are directly discarded after use, which not only wastes resources, but also brings certain environmental problems. Therefore, a recycling method for recycled paper-plastic composite bags is urgently needed. Summary of the invention

[0004] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a recycling method for recycled paper-plastic composite bags.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for recycling recycled paper-plastic composite bags comprises the following steps:

[0007] S1. Raw material screening;

[0008] A. The collected recycled paper-plastic composite bags are sorted manually, and the staff will recycle the metal, plastic bottles, glass bottles, stones and other obvious impurities mixed in the bags, as well as the bags that are severely damaged and cannot be reused;

[0009] B. After being processed by S1-A, the recyclable recycled paper-plastic composite bags are sent to a cleaning device for cleaning. The cleaning device is specifically a high-pressure water gun and a spray mechanism, which strongly washes the surface of the waste bags to remove stains, dust and residues on the surface;

[0010] C. After S1-B treatment, secondary screening and sorting are performed;

[0011] S2, initial processing of raw materials;

[0012] A. Crushing, specifically, sending the raw materials collected in S1 to a crusher for crushing, breaking the bags into smaller pieces, and then collecting the crushed pieces in a centralized manner;

[0013] B. Perform pretreatment, including removing moisture, oil and residue, and drying the bag fragments in S2-A with hot air in a dryer to ensure that the fragments are dry and clean;

[0014] C. Chemical separation treatment: pour the dried bag fragments into a container containing tetrahydrofuran solvent and completely immerse them in the solvent. Then, the solvent is heated to promote the dissolution of the plastic. After heating, the solvent is continuously stirred at a uniform speed so that the solvent can be quickly integrated with the plastic and the recycled paper can be quickly separated from the surface of the plastic.

[0015] D. After the plastic component is fully dissolved in the solvent, the mixture is filtered through a filtering device to collect and remove undissolved recycled paper fibers and other impurities;

[0016] E. Collect the filtrate and send the solvent containing the dissolved plastic components to a concentrator to remove the solvent and recover the plastic components;

[0017] S3, raw material recycling processing;

[0018] A. Processing of recycled paper fibers: sending them to a paper shredder for further shredding, and then putting the shredded recycled paper fragments into a pulper, adding an appropriate amount of water for shredding, the recycled paper fragments are further broken into fibrous substances to form paper pulp, and then the larger impurities and fiber bundles in the waste paper pulp are removed through screening equipment to obtain a more uniform waste paper pulp;

[0019] B. pH adjustment, deinking, bleaching, and making pulp from mechanical pulp;

[0020] S4, enhanced processing of raw materials;

[0021] A. adding cellulase and hemicellulase into the pulp, stirring it synchronously with a stirring device, and allowing it to stand for a static treatment after the stirring is completed;

[0022] B. Adding polyhydroxyalkanoate to the mixed slurry, the polyhydroxyalkanoate accounts for 2-3% of the total slurry volume, and then heating the mixed slurry and stirring it continuously, and after the stirring is completed, standing it to cool down to room temperature;

[0023] C. The cooled mixed slurry is screened by filtering equipment to separate the long and short fibers in the slurry, and then the short fiber slurry is refined by a refiner to obtain a finer slurry, thereby improving the fiber bonding force and strength of the paper;

[0024] D. Add the short fiber slurry into the container and use the ultrasonic generator to perform cavitation and shearing on the slurry, thereby destroying the hydrogen bonds and van der Waals forces between the fibers and promoting the rearrangement and bonding of the fibers;

[0025] S5. Recycling;

[0026] A. The long and short fibers obtained in S4 are processed by a paper machine in the same manner, wherein the obtained paper is sent to a corresponding factory for use;

[0027] B. Process the plastic raw materials processed in S2 and send them to the corresponding project.

[0028] Preferably, the solvent can be reused through a condensation and recovery system to reduce waste and environmental pollution, wherein the separated recycled paper fibers and plastics need to be purified before being sent to subsequent processing.

[0029] Preferably, after the S4 medium and long fibers are separated, they are prepared using the same additives and processing technology as the short fibers.

[0030] Preferably, after the long and short fibers are prepared, the recycled paper made from the long and short fibers is used as the outer layer and inner layer of the recycled paper-plastic composite bag, respectively.

[0031] Preferably, before the processing of the recycled paper fragments in S2, the recycled paper fragments are centrifuged by a centrifugal device to remove some debris on the surface thereof.

[0032] Preferably, during the preparation of S3, a mixture of hydrogen peroxide and sodium hydroxide is used to effectively remove impurities and ink from the pulp while reducing damage to the fibers.

[0033] Preferably, in the preparation process of S4, the corresponding mass ratio of cellulase to hemicellulase is 3:1.3, wherein the ratio of the total mass of cellulase and hemicellulase to the total mass of pulp is 0.1-0.3:3.

[0034] Preferably, after the mechanical pulping is completed, the pulp is pressed, and the pressing pressures of the long and short limits are different, and the specific pressure ratio is 1.2:0.9.

[0035] Preferably, during the drying process, the drying temperature is controlled between 80 and 120°C.

[0036] The beneficial effects of the present invention are:

[0037] In the present invention, the pulp of waste recycled paper is strengthened by adding cellulase to modify secondary fibers and strengthening the paper fiber bonding through polyhydroxyalkanoates to improve the strength of the paper. At the same time, through the differentiation and utilization of long and short fibers, the long and short fibers are respectively prepared into the inner and outer layers of the bag body. The different characteristics of the long and short fibers and the strength of the paper are used to improve the overall strength of the recycled bag, thereby effectively increasing the recycling efficiency of the recycled paper. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0039] A method for recycling recycled paper-plastic composite bags comprises the following steps:

[0040] S1. Raw material screening;

[0041] A. The collected recycled paper-plastic composite bags are sorted manually, and the staff will recycle the metal, plastic bottles, glass bottles, stones and other obvious impurities mixed in the bags, as well as the bags that are severely damaged and cannot be reused;

[0042] B. After being processed by S1-A, the recyclable recycled paper-plastic composite bags are sent to a cleaning device for cleaning. The cleaning device is specifically a high-pressure water gun and a spray mechanism, which strongly washes the surface of the waste bags to remove stains, dust and residues on the surface;

[0043] C. After S1-B treatment, secondary screening and sorting are performed;

[0044] S2, initial processing of raw materials;

[0045] A. Crushing, specifically, sending the raw materials collected in S1 to a crusher for crushing, breaking the bags into smaller pieces, and then collecting the crushed pieces in a centralized manner;

[0046] B. Perform pretreatment, including removing moisture, oil and residue, and drying the bag fragments in S2-A with hot air in a dryer to ensure that the fragments are dry and clean;

[0047] C. Chemical separation treatment: pour the dried bag fragments into a container containing tetrahydrofuran solvent and completely immerse them in the solvent. Then, the solvent is heated to promote the dissolution of the plastic. After heating, the solvent is continuously stirred at a uniform speed so that the solvent can be quickly integrated with the plastic and the recycled paper can be quickly separated from the surface of the plastic.

[0048] D. After the plastic component is fully dissolved in the solvent, the mixture is filtered through a filtering device to collect and remove undissolved recycled paper fibers and other impurities;

[0049] E. Collect the filtrate and send the solvent containing the dissolved plastic components to a concentrator to remove the solvent and recover the plastic components;

[0050] S3, raw material recycling processing;

[0051] A. Processing of recycled paper fibers: sending them to a paper shredder for further shredding, and then putting the shredded recycled paper fragments into a pulper, adding an appropriate amount of water for shredding, the recycled paper fragments are further broken into fibrous substances to form paper pulp, and then the larger impurities and fiber bundles in the waste paper pulp are removed through screening equipment to obtain a more uniform waste paper pulp;

[0052] B. pH adjustment, deinking, bleaching, and making pulp from mechanical pulp;

[0053] S4, enhanced processing of raw materials;

[0054] A. adding cellulase and hemicellulase into the pulp, stirring it synchronously with a stirring device, and allowing it to stand for a static treatment after the stirring is completed;

[0055] B. Adding polyhydroxyalkanoate to the mixed slurry, the polyhydroxyalkanoate accounts for 2-3% of the total slurry volume, and then heating the mixed slurry and stirring it continuously, and after the stirring is completed, standing it to cool down to room temperature;

[0056] C. The cooled mixed slurry is screened by filtering equipment to separate the long and short fibers in the slurry, and then the short fiber slurry is refined by a refiner to obtain a finer slurry, thereby improving the fiber bonding force and strength of the paper;

[0057] D. Add the short fiber slurry into the container and use the ultrasonic generator to perform cavitation and shearing on the slurry, thereby destroying the hydrogen bonds and van der Waals forces between the fibers and promoting the rearrangement and bonding of the fibers;

[0058] S5. Recycling;

[0059] A. The long and short fibers obtained in S4 are processed by a paper machine in the same manner, wherein the obtained paper is sent to a corresponding factory for use;

[0060] B. Process the plastic raw materials processed in S2 and send them to the corresponding project.

[0061] Furthermore, the solvent can be reused through a condensation and recovery system to reduce waste and environmental pollution, wherein the separated recycled paper fibers and plastics need to be purified before being sent to subsequent processing.

[0062] Furthermore, after the long and medium fibers of S4 are separated, they are prepared using the same additives and processing technology as the short fibers. By separating and utilizing the long and short fibers, the inner and outer bags of recycled paper-plastic plastic belts are prepared through the different strengths and properties of the long and short fibers.

[0063] Furthermore, after the long and short fibers are prepared, the recycled paper made from the long and short fibers is used as the outer layer and inner layer of the recycled paper-plastic composite bag respectively.

[0064] Furthermore, before the processing of the recycled paper fragments in S2, the recycled paper fragments are centrifuged by a centrifugal device to remove some debris on the surface thereof.

[0065] Furthermore, during the preparation of S3, a mixture of hydrogen peroxide and sodium hydroxide is used to effectively remove impurities and ink from the pulp while reducing damage to the fibers.

[0066] Furthermore, during the preparation of S4, the corresponding mass ratio of cellulase to hemicellulase is 3:1.3, wherein the ratio of the total mass of cellulase and hemicellulase to the total mass of pulp is 0.1-0.3:3.

[0067] Furthermore, after the mechanical pulping is completed, the pulp is pressed, and the pressing pressures of the long and short limits are different, and the specific pressure ratio is 1.2:0.9.

[0068] Furthermore, during the drying process, the drying temperature is controlled between 80 and 120°C.

[0069] In this embodiment, during the raw material screening stage, the collected recycled paper-plastic composite bags are manually preliminarily sorted to screen out obvious impurities such as metals, plastic bottles, glass bottles, stones, etc. in the bags, while those bags that are severely damaged and cannot be reused are processed in a centralized manner.

[0070] Then, the recyclable recycled paper-plastic composite bags are sent to the cleaning equipment for cleaning, so as to remove oil stains, sludge, dust and residues on the surface of the bag, thereby ensuring the efficiency of subsequent processing, and at the same time, the bag can be disinfected as a whole.

[0071] After processing, the processed waste recycled paper is shredded, the bags are broken into smaller pieces, and then the broken pieces are collected and dried with hot air in a dryer. The wet pieces after washing are dried, and then the dried paper pieces are screened for the second time to remove debris that was not found the first time.

[0072] Then, the paper fragments after the second screening are chemically separated, and the dried bag fragments are poured into a container containing tetrahydrofuran solvent and completely immersed in the solvent. The solvent is then heated to promote the dissolution of the plastic, and after heating, it is continuously stirred at a uniform speed so that the solvent can quickly merge with the plastic and the recycled paper can quickly separate from the plastic surface. After the plastic component is fully dissolved in the solvent, the mixture is filtered through a filtering device to collect and remove undissolved recycled paper fibers and other impurities.

[0073] Furthermore, the paper fibers and plastic components in the solution are filtered and screened.

[0074] Among them, when processing recycled paper fibers, the processed paper fibers are sent to a paper shredder for further pulverization, and then the pulverized recycled paper fragments are placed in a pulper, and an appropriate amount of water is added for pulverization. The recycled paper fragments are further broken into fibrous substances to form pulp, and then the larger impurities and fiber bundles in the waste paper pulp are removed through screening equipment to obtain a more uniform waste paper pulp.

[0075] After the process is completed, enhanced treatment is carried out, specifically, by adding solvents such as cellulase, hemicellulase, polyhydroxyalkanoate, etc. into the mixed slurry, and improving the overall connection strength and chemical properties of the fibers, and then screening the long and short fibers in the slurry, and passing the short fiber slurry through a refining machine to refine the slurry to obtain a more delicate slurry, thereby improving the fiber bonding force and strength of the paper, and then adding the short fiber slurry into a container, and subjecting the slurry to cavitation and shearing effects through an ultrasonic generator, thereby destroying the hydrogen bonds and van der Waals forces between the fibers, and promoting the rearrangement and bonding of the fibers, and after the process is completed, the long and short fibers are processed with the same process through a papermaking machine, and the resulting paper is sent to the corresponding factory.

[0076] In the present invention, the pulp of waste recycled paper is strengthened by adding cellulase to modify secondary fibers and strengthening the paper fiber bonding through polyhydroxyalkanoates to improve the strength of the paper. At the same time, through the differentiation and utilization of long and short fibers, the long and short fibers are respectively prepared into the inner and outer layers of the bag body. The different characteristics of the long and short fibers and the strength of the paper are used to improve the overall strength of the recycled bag, thereby effectively increasing the recycling efficiency of the recycled paper.

[0077] The recycled paper-plastic composite bags prepared in the above embodiments were selected for strength testing, and the test environment, time and other conditions were the same (A, B, and C were ordinary paper-plastic composite bags, reinforced paper-plastic composite bags, food-grade paper-plastic composite bags, and environmentally friendly recycled paper bags on the market, respectively, and D was the recycled paper-plastic composite bag prepared in this technical solution).

[0078]

[0079] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for recycling recycled paper-plastic composite bags, characterized in that: The following steps are involved: S1. Raw material screening; A. The collected recycled paper-plastic composite bags are sorted manually, and the staff will recycle the metal, plastic bottles, glass bottles, stones and other obvious impurities mixed in the bags, as well as the bags that are severely damaged and cannot be reused; B. After being processed by S1-A, the recyclable recycled paper-plastic composite bags are sent to a cleaning device for cleaning. The cleaning device is specifically a high-pressure water gun and a spray mechanism, which strongly washes the surface of the waste bags to remove stains, dust and residues on the surface; C. After S1-B treatment, secondary screening and sorting are performed; S2, initial processing of raw materials; A. Crushing, specifically, sending the raw materials collected in S1 to a crusher for crushing, breaking the bags into smaller pieces, and then collecting the crushed pieces in a centralized manner; B. Perform pretreatment, including removing moisture, oil and residue, and drying the bag fragments in S2-A with hot air in a dryer to ensure that the fragments are dry and clean; C. Chemical separation treatment: pour the dried bag fragments into a container containing tetrahydrofuran solvent and completely immerse them in the solvent. Then, the solvent is heated to promote the dissolution of the plastic. After heating, the solvent is continuously stirred at a uniform speed so that the solvent can be quickly integrated with the plastic and the recycled paper can be quickly separated from the surface of the plastic. D. After the plastic component is fully dissolved in the solvent, the mixture is filtered through a filtering device to collect and remove undissolved recycled paper fibers and other impurities; E. Collect the filtrate and send the solvent containing the dissolved plastic components to a concentrator to remove the solvent and recover the plastic components; S3, raw material recycling processing; A. Processing of recycled paper fibers: sending them to a paper shredder for further shredding, and then putting the shredded recycled paper fragments into a pulper, adding an appropriate amount of water for shredding, the recycled paper fragments are further broken into fibrous substances to form paper pulp, and then the larger impurities and fiber bundles in the waste paper pulp are removed through screening equipment to obtain a more uniform waste paper pulp; B. pH adjustment, deinking, bleaching, and making pulp from mechanical pulp; S4, enhanced processing of raw materials; A. adding cellulase and hemicellulase into the pulp, stirring it synchronously with a stirring device, and allowing it to stand for a static treatment after the stirring is completed; B. Adding polyhydroxyalkanoate to the mixed slurry, the polyhydroxyalkanoate accounts for 2-3% of the total slurry volume, and then heating the mixed slurry and stirring it continuously, and after the stirring is completed, standing it to cool down to room temperature; C. The cooled mixed slurry is screened by filtering equipment to separate the long and short fibers in the slurry, and then the short fiber slurry is refined by a refiner to obtain a finer slurry, thereby improving the fiber bonding force and strength of the paper; D. Add the short fiber slurry into the container and use the ultrasonic generator to perform cavitation and shearing on the slurry, thereby destroying the hydrogen bonds and van der Waals forces between the fibers and promoting the rearrangement and bonding of the fibers; S5. Recycling; A. The long and short fibers obtained in S4 are processed by a paper machine in the same manner, wherein the obtained paper is sent to a corresponding factory for use; B. Process the plastic raw materials processed in S2 and send them to the corresponding project.

2. The method for recycling recycled paper-plastic composite bags according to claim 1, characterized in that: The solvent can be reused through a condensation and recovery system to reduce waste and environmental pollution, wherein the separated recycled paper fibers and plastics need to be purified before being sent to subsequent processing.

3. The method for recycling recycled paper-plastic composite bags according to claim 1, characterized in that: After being separated, the S4 medium and long fibers are prepared using the same additives and processing techniques as the short fibers.

4. The method for recycling recycled paper-plastic composite bags according to claim 1, characterized in that: After the long and short fibers are prepared, the recycled paper made from the long and short fibers is used as the outer layer and inner layer of the recycled paper-plastic composite bag respectively.

5. The method for recycling recycled paper-plastic composite bags according to claim 1, characterized in that: Before the processing of the recycled paper fragments in S2, the recycled paper fragments are centrifuged by a centrifugal device to remove some debris on the surface of the recycled paper fragments.

6. The method for recycling recycled paper-plastic composite bags according to claim 1, characterized in that: During the preparation of S3, a mixture of hydrogen peroxide and sodium hydroxide is used to effectively remove impurities and ink from the pulp, while reducing damage to the fibers.

7. The method for recycling recycled paper-plastic composite bags according to claim 1, characterized in that: During the preparation of S4, the corresponding mass ratio of cellulase to hemicellulase is 3:1.3, wherein the ratio of the total mass of cellulase and hemicellulase to the total mass of pulp is 0.1-0.3:

3.

8. The method for recycling recycled paper-plastic composite bags according to claim 1, characterized in that: After the mechanical pulping is completed, the pulp is pressed, and the pressing pressures of the long and short limits are different, and the specific pressure ratio is 1.2:0.

9.

9. The method for recycling recycled paper-plastic composite bags according to claim 1, characterized in that: During the drying process, the drying temperature is controlled between 80 and 120°C.

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