Paper-plastic composite paper for woven bags and preparation method of paper-plastic composite paper
By mixing waste paper in a specific ratio and combining it with a plastic layer to prepare paper-plastic composite materials, the problems of insufficient air permeability and strength of recycled paper are solved, and high-performance, low-cost paper materials for woven bags are realized.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-27
- Publication Date
- 2026-05-19
AI Technical Summary
Existing recycled paper has poor air permeability and strength, making it difficult to meet the application requirements of high-demand products, resulting in a decline in economic value.
Paper-plastic composite paper is prepared by mixing cardboard boxes, book pages, milk cartons, and high-temperature paper in a specific ratio, and then processing it through pulping, screening, beating, and sizing. The paper is then combined with a plastic layer to form a paper-plastic composite material.
The resulting paper-plastic composite paper has an air permeability of 8S and a tensile strength comparable to that of brand-new kraft paper, resulting in significantly reduced costs and increased economic value.
Smart Images
Figure SMS_1
Abstract
Description
Technical Field
[0001] This invention relates to the field of paper materials, and in particular to a paper-plastic composite paper for woven bags and its preparation method. Background Technology
[0002] With the continuous strengthening of environmental protection concepts, the reuse of paper has received increasing attention. However, current paper reuse methods lack relevant research on the combination of different types of waste paper. In practice, different types of waste paper are often mixed randomly or a single type of waste paper is used for recycling. Paper produced by this recycling method usually has relatively poor performance, especially in terms of air permeability and strength. This narrows the application range of recycled paper and makes it difficult to use in products with high requirements for paper performance, thus reducing the economic value of recycled paper. Therefore, there is still room for improvement. Summary of the Invention
[0003] To improve the air permeability and strength of recycled paper, this application provides a paper-plastic composite paper for woven bags and a method for preparing the same.
[0004] In a first aspect, this application provides a method for preparing a paper-plastic composite paper for woven bags, employing the following technical solution: A method for preparing a paper-plastic composite paper for woven bags includes the following steps: Step 1) Mix the cardboard boxes, book pages, milk cartons, and high-temperature paper in a mass ratio of 3.5-4.5:5.5-6.5:2.5-3.5:1.5-2.5 to obtain the mixed raw materials; Step 2) Mix the raw materials, water, deinking agent, and sodium hydroxide, and then pulp them using a pulping device to obtain coarse pulp; Step 3) The coarse pulp is screened to remove slag, and then pulped using a pulping device to obtain refined pulp; Step 4) Add sizing agent and wet strength agent to the pulp, then feed it into the papermaking equipment, and after forming, pressing and dewatering, and drying, obtain the base paper; Step 5) The base paper and the plastic layer are combined through a thermal lamination process to obtain paper-plastic composite paper for woven bags.
[0005] By adopting the above technical solution, and by combining cardboard boxes, book pages, milk cartons, and high-temperature paper in a specific ratio, various types of fiber structures can be fully utilized to form a special structure under specific proportions. The resulting base paper has high strength and air permeability. The tensile strength of the base paper reaches the level of new kraft paper, and the air permeability reaches 8S. The final composite paper has excellent performance and can well meet the needs of woven bags. At the same time, the cost is significantly reduced compared to new kraft paper, which has high economic value.
[0006] Preferably, in step 2), during the pulping process, the pulping temperature is controlled at 20-45℃, the pulp concentration is 3.5-4.5%, the amount of deinking agent is 0.8-1.2% of the mass of the mixed raw materials, and the amount of sodium hydroxide is 1.3-1.7% of the mass of the mixed raw materials.
[0007] By adopting the above technical solution and controlling the pulp concentration, the pulping effect is better, which can fully mix the fibers in various types of waste paper and effectively improve the quality of the base paper.
[0008] Preferably, in step 3), during the screening and slag removal process, the refined pulp is diluted to a pulp mass concentration of 1.0-1.3%, and then centrifugation, slag removal, filtration, and foaming deinking are performed sequentially.
[0009] By adopting the above technical solution, and by removing slag at a pulp concentration of 1.0-1.3%, the impurity removal effect is better, and the quality of the resulting base paper is better.
[0010] Preferably, in step 3), during the foaming deinking process, 0.8-1.2% of the mass of the mixed raw materials of the deinking agent is added to the slurry, air is injected to generate a large number of bubbles, the foam is scraped off, and the deinking is completed.
[0011] By adopting the above technical solution and adding deinking agent twice, the ink in waste paper can be removed more effectively, resulting in better color of the original paper.
[0012] Preferably, in step 3), the mass concentration of the refined pulp obtained after pulping is 3.5-4.5%, the wet weight is 6.0-8.0, and the freeness is 37-39°SR.
[0013] By adopting the above technical solutions and controlling the wet weight and beating degree of the refined pulp, the resulting base paper has better quality and higher strength.
[0014] Preferably, in step 4), the amount of sizing agent is 0.1-0.2% of the mass of the mixed raw materials, and the amount of wet strength agent is 1.6-1.8% of the mass of the mixed raw materials.
[0015] By adopting the above technical solution and by specifically selecting the dosage of sizing agent and wet strength agent, the strength of the base paper can be improved. Furthermore, based on the synergistic effect of various types of fibers in the base paper, the base paper can have sufficiently high strength with a small amount of sizing agent and wet strength agent, resulting in a higher utilization rate when the base paper is recycled.
[0016] Preferably, the sizing agent is AKD sizing agent, and the wet strength agent is PAE wet strength agent.
[0017] By adopting the above technical solutions and specifically selecting AKD sizing agent and PAE wet strength agent, the effect of improving the strength of the base paper is even better.
[0018] Preferably, in step 4), during web forming, the web concentration is controlled at 0.6-0.9%, the pulp-to-web speed ratio is 0.95-1.00 (total pressure head), the lip opening is 18-21mm, and the dryness of the web exit section is 19-22%; during press dewatering, the pressure of the first press line is controlled at 3.5 BAR, the pressure of the second press line is 3.5-4.0 BAR, the pressure of the third press line is 3.0-3.5 BAR, and the dryness of the press exit section is 42-47%; during drying, the steam pressure of the first cylinder is controlled at 0.3-0.5 BAR, the steam pressure of the second cylinder is 0.6-0.9 BAR, the steam pressure of the third cylinder is 1.2-1.5 BAR, and the moisture content of the paper exiting the drying cylinder is 7.5-9.5%.
[0019] By adopting the above technical solution, the resulting base paper has uniform quality and strength distribution, is less prone to local weak points, and has better overall quality.
[0020] Preferably, in step 5), the plastic layer is a polypropylene flat filament woven fabric.
[0021] By adopting the above technical solution and using polypropylene flat yarn woven fabric, the resulting paper-plastic composite paper is of higher quality and better meets the needs of woven bags.
[0022] Secondly, this application provides a paper-plastic composite paper for woven bags, employing the following technical solution: A paper-plastic composite paper for woven bags is prepared by the above-described method for preparing paper-plastic composite paper for woven bags.
[0023] By adopting the above technical solution, the paper-plastic composite paper raw material used for woven bags is made from waste paper, which reduces costs and ensures that the air permeability and strength meet the requirements of woven bags, thus having high economic value.
[0024] In summary, this application has the following beneficial effects: 1. Because this application uses a specific ratio of cardboard boxes, book pages, milk cartons, and high-temperature paper, it can fully utilize various types of fiber structures to form a special structure under specific ratios. The resulting base paper has high strength and air permeability. The tensile strength of the base paper reaches the level of new kraft paper, and the air permeability reaches 8S. The final composite paper has better performance and can well meet the needs of woven bags. At the same time, the cost is significantly reduced compared to new kraft paper, which has high economic value.
[0025] 2. In this application, it is preferred to control the pulp concentration during pulping to achieve better pulping effect, which can fully mix the fibers in various types of waste paper. Furthermore, by removing slag at a pulp concentration of 1.0-1.3%, the impurity removal effect is better, resulting in higher quality base paper.
[0026] 3. In this application, it is preferred to control the wet weight and beating degree of the pulp to obtain a base paper with better quality and higher strength. Detailed Implementation
[0027] The present application will be further described in detail below with reference to the embodiments. Example 1
[0028] A paper-plastic composite paper for woven bags, the preparation method includes the following steps: Step 1) Dry the cardboard boxes, book pages, milk cartons, and high-temperature paper at 100℃ for 4 hours. Then weigh 350kg of cardboard boxes, 550kg of book pages, 250kg of milk cartons, and 150kg of high-temperature paper, and mix them to obtain mixed raw materials.
[0029] Step 2) Mix the raw materials, water, deinking agent, and sodium hydroxide and put them into a pulper for pulping to obtain coarse pulp. During the pulping process, control the pulping temperature to 20℃, the pulp mass concentration to 3.5%, the amount of deinking agent to be 0.8% of the mass of the raw materials, and the amount of sodium hydroxide to be 1.3% of the mass of the raw materials.
[0030] Step 3) Dilute the coarse pulp with water to a pulp concentration of 1.0%, then put it into a centrifugal desander for high-speed rotation to remove heavy impurities. Then use a pulp filter screen to remove fine and flat impurities. Next, add 0.8% of the mixed raw material mass of deinking agent to the pulp, inject air to generate a large number of bubbles, scrape off the foam, and then put the desandered pulp into a polishing machine for beating to obtain a polished pulp with a mass concentration of 3.5%, a wet weight of 6.0, and a freeness of 37°SR.
[0031] Step 4): Add sizing agent and wet strength agent to the refined pulp. The amount of sizing agent is 0.1% of the mass of the mixed raw materials, and the amount of wet strength agent is 1.6% of the mass of the mixed raw materials. After mixing evenly, feed the mixture into the papermaking equipment and sequentially perform wire forming, press dewatering, and drying to obtain the base paper. During wire forming, control the wire density at 0.6%, the pulp-wire speed ratio at 0.95 (total press head), the lip opening at 18mm, and the dryness of the wire exit section at 19%. During press dewatering, control the pressure of the first press line at 3.5 BAR, the pressure of the second press line at 3.5 BAR, the pressure of the third press line at 3.0 BAR, and the dryness of the paper exiting the press at 42%. During drying, control the steam pressure of the first cylinder at 0.3 BAR, the steam pressure of the second cylinder at 0.6 BAR, and the steam pressure of the third cylinder at 1.2 BAR, and the moisture content of the paper exiting the drying cylinder at 7.5%.
[0032] Step 5) The base paper and the plastic layer are combined through a thermal lamination process to obtain paper-plastic composite paper for woven bags.
[0033] The deinking agent was purchased from Fengtai Environmental Protection Technology (Shandong) Co., Ltd., model: FT-T130.
[0034] The sizing agent is AKD sizing agent, purchased from Wuxi Tianxin Chemical Co., Ltd., model: LS-A15.
[0035] The wet strength agent is PAE wet strength agent, purchased from Qingzhou Jinhao New Materials Co., Ltd., model: JH-1201.
[0036] The plastic layer is made of polypropylene flat filament woven fabric, purchased from Shandong Dexuda Geotechnical Materials Co., Ltd., model: 98 grams.
[0037] Cardboard boxes are recycled kraft paper boxes used for packaging.
[0038] The pages are the pages from old, discarded books, excluding the cover.
[0039] The milk cartons are recycled dairy product packaging boxes.
[0040] High-temperature paper is recycled baking silicone paper. Example 2
[0041] A paper-plastic composite paper for woven bags, the preparation method includes the following steps: Step 1) Dry the cardboard boxes, book pages, milk cartons, and high-temperature paper at 100℃ for 5 hours. Then weigh 400kg of cardboard boxes, 600kg of book pages, 300kg of milk cartons, and 200kg of high-temperature paper, and mix them to obtain mixed raw materials.
[0042] Step 2) Mix the raw materials, water, deinking agent, and sodium hydroxide and put them into a pulper for pulping to obtain coarse pulp. During the pulping process, control the pulping temperature to 30℃, the pulp mass concentration to 4%, the amount of deinking agent to 1% of the mass of the raw materials, and the amount of sodium hydroxide to 1.5% of the mass of the raw materials.
[0043] Step 3) Dilute the coarse pulp with water to a pulp concentration of 1.2%, then put it into a centrifugal desander for high-speed rotation to remove heavy impurities. Then use a pulp filter screen to remove fine and flat impurities. Next, add 1% of the mass of the mixed raw materials as deinking agent to the pulp, inject air to generate a large number of bubbles, scrape off the foam, and then put the desandered pulp into a polishing machine for beating to obtain a polished pulp with a mass concentration of 4%, a wet weight of 7.0, and a freeness of 38°SR.
[0044] Step 4): Add sizing agent and wet strength agent to the refined pulp. The amount of sizing agent is 0.15% of the mass of the mixed raw materials, and the amount of wet strength agent is 1.7% of the mass of the mixed raw materials. After mixing evenly, send it to the papermaking equipment for sequential web forming, press dewatering, and drying to obtain the base paper. During web forming, control the web concentration at 0.8%, the pulp-to-web speed ratio at 0.98 (total press head), the lip opening at 20mm, and the dryness of the exit section at 20%. During press dewatering, control the pressure of the first press line at 3.5 BAR, the pressure of the second press line at 3.8 BAR, the pressure of the third press line at 3.2 BAR, and the dryness of the exit press at 45%. During drying, control the steam pressure of the first cylinder at 0.4 BAR, the steam pressure of the second cylinder at 0.8 BAR, and the steam pressure of the third cylinder at 1.3 BAR, and the moisture content of the paper exiting the drying cylinder at 8%.
[0045] Step 5) The base paper and the plastic layer are combined through a thermal lamination process to obtain paper-plastic composite paper for woven bags.
[0046] The deinking agent was purchased from Fengtai Environmental Protection Technology (Shandong) Co., Ltd., model: FT-T130.
[0047] The sizing agent is AKD sizing agent, purchased from Wuxi Tianxin Chemical Co., Ltd., model: LS-A15.
[0048] The wet strength agent is PAE wet strength agent, purchased from Qingzhou Jinhao New Materials Co., Ltd., model: JH-1201.
[0049] The plastic layer is made of polypropylene flat filament woven fabric, purchased from Shandong Dexuda Geotechnical Materials Co., Ltd., model: 98 grams.
[0050] Cardboard boxes are recycled kraft paper boxes used for packaging.
[0051] The pages are the pages from old, discarded books, excluding the cover.
[0052] The milk cartons are recycled dairy product packaging boxes.
[0053] High-temperature paper is recycled baking silicone paper. Example 3
[0054] A paper-plastic composite paper for woven bags, the preparation method includes the following steps: Step 1) Dry the cardboard boxes, book pages, milk cartons, and high-temperature paper at 100℃ for 6 hours. Then weigh 450kg of cardboard boxes, 650kg of book pages, 350kg of milk cartons, and 250kg of high-temperature paper, and mix them to obtain mixed raw materials.
[0055] Step 2) Mix the raw materials, water, deinking agent, and sodium hydroxide and put them into a pulper for pulping to obtain coarse pulp. During the pulping process, control the pulping temperature to 45℃, the pulp mass concentration to 4.5%, the amount of deinking agent to be 1.2% of the mass of the raw materials, and the amount of sodium hydroxide to be 1.7% of the mass of the raw materials.
[0056] Step 3) Dilute the coarse pulp with water to a pulp concentration of 1.3%, then put it into a centrifugal desander for high-speed rotation to remove heavy impurities. Then use a pulp filter screen to remove fine and flat impurities. Next, add 1.2% of the mixed raw material mass of deinking agent to the pulp, inject air to generate a large number of bubbles, scrape off the foam, and then put the desandered pulp into a polishing machine for beating to obtain a polished pulp with a mass concentration of 4.5%, a wet weight of 8.0, and a freeness of 39°SR.
[0057] Step 4): Add sizing agent and wet strength agent to the refined pulp. The amount of sizing agent is 0.2% of the mass of the mixed raw materials, and the amount of wet strength agent is 1.8% of the mass of the mixed raw materials. After mixing evenly, feed the mixture into the papermaking equipment and sequentially perform wire forming, press dewatering, and drying to obtain the base paper. During wire forming, control the wire density at 0.9%, the pulp-to-wire speed ratio at 1.00 (total press head), the lip opening at 21mm, and the dryness of the wire exit section at 22%. During press dewatering, control the pressure of the first press line at 3.5 BAR, the pressure of the second press line at 4.0 BAR, the pressure of the third press line at 3.5 BAR, and the dryness of the paper exiting the press at 47%. During drying, control the steam pressure of the first cylinder at 0.5 BAR, the steam pressure of the second cylinder at 0.9 BAR, and the steam pressure of the third cylinder at 1.5 BAR, and the moisture content of the paper exiting the drying cylinder at 9.5%.
[0058] Step 5) The base paper and the plastic layer are combined through a thermal lamination process to obtain paper-plastic composite paper for woven bags.
[0059] The deinking agent was purchased from Fengtai Environmental Protection Technology (Shandong) Co., Ltd., model: FT-T130.
[0060] The sizing agent is AKD sizing agent, purchased from Wuxi Tianxin Chemical Co., Ltd., model: LS-A15.
[0061] The wet strength agent is PAE wet strength agent, purchased from Qingzhou Jinhao New Materials Co., Ltd., model: JH-1201.
[0062] The plastic layer is made of polypropylene flat filament woven fabric, purchased from Shandong Dexuda Geotechnical Materials Co., Ltd., model: 98 grams.
[0063] Cardboard boxes are recycled kraft paper boxes used for packaging.
[0064] The pages are the pages from old, discarded books, excluding the cover.
[0065] The milk cartons are recycled dairy product packaging boxes.
[0066] High-temperature paper is recycled baking silicone paper.
[0067] Comparative Example 1 A paper-plastic composite paper for woven bags, differing from Example 2 only in that: Replace the book pages with an equal amount of cardboard boxes.
[0068] Cardboard boxes are recycled kraft paper boxes used for packaging.
[0069] Comparative Example 2 Replace milk cartons with cardboard boxes of equal quantity.
[0070] Cardboard boxes are recycled kraft paper boxes used for packaging.
[0071] Comparative Example 3 Replace the high-temperature paper with an equal amount of cardboard boxes.
[0072] Cardboard boxes are recycled kraft paper boxes used for packaging.
[0073] Comparative Example 4 A paper-plastic composite paper for woven bags, differing from Example 2 only in that: Replace book pages with an equal amount of leather cardboard boxes, replace milk cartons with an equal amount of leather cardboard boxes, and replace high-temperature paper with an equal amount of leather cardboard boxes.
[0074] Cardboard boxes are recycled kraft paper boxes used for packaging.
[0075] Comparative Example 5 A paper-plastic composite paper for woven bags, differing from Example 2 only in that: In step 1), the weights of the cardboard boxes, book pages, milk cartons, and high-temperature paper are adjusted as follows: 200kg cardboard boxes, 800kg book pages, 100kg milk cartons, and 400kg high-temperature paper.
[0076] Comparative Example 6 A paper-plastic composite paper for woven bags, differing from Example 2 only in that: In step 1), the weights of the cardboard boxes, book pages, milk cartons, and high-temperature paper are adjusted as follows: 600kg cardboard boxes, 400kg book pages, 450kg milk cartons, and 50kg high-temperature paper.
[0077] Experiment 1 The air permeability P and air resistance of the base paper prepared in each example and comparative example were determined according to the Gurley method in GB / T 458-2008 "Determination of air permeability of paper and paperboard".
[0078] Experiment 2 The longitudinal tensile strength of the base paper prepared in each example and comparative example was determined according to GB / T 12914-2018 "Determination of tensile strength of paper and paperboard - constant speed tensile method (20 mm / min)".
[0079] The experimental data for Experiments 1-2 are detailed in Table 1.
[0080] Table 1
[0081] According to the data comparison in Table 1, the air permeability and strength properties of the base paper prepared in each embodiment are significantly better than those in the comparative examples. It can be seen that by using waste cardboard boxes, book pages, milk cartons, and high-temperature paper in a specific ratio as raw materials for recycled paper, the air permeability and strength properties of recycled paper can be significantly improved by making full use of the interaction of various fiber structures. There is no need to add a large amount of chemical modifiers, the production process is more green and environmentally friendly, and the cost is lower, which has higher economic value.
[0082] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.
Claims
1. A method for preparing a paper-plastic composite paper for woven bags, characterized in that: Includes the following steps: Step 1) Mix the cardboard boxes, book pages, milk cartons, and high-temperature paper in a mass ratio of 3.5-4.5:5.5-6.5:2.5-3.5:1.5-2.5 to obtain the mixed raw materials; Step 2) Mix the raw materials, water, deinking agent, and sodium hydroxide, and then pulp them using a pulping device to obtain coarse pulp; Step 3) The coarse pulp is screened to remove slag, and then pulped using a pulping device to obtain refined pulp; Step 4) Add sizing agent and wet strength agent to the pulp, then feed it into the papermaking equipment, and after forming, pressing and dewatering, and drying, obtain the base paper; Step 5) The base paper and the plastic layer are combined through a thermal lamination process to obtain a paper-plastic composite paper for woven bags.
2. The method for preparing a paper-plastic composite paper for woven bags according to claim 1, characterized in that: In step 2), during the pulping process, the pulping temperature is controlled at 20-45℃, the pulp mass concentration is 3.5-4.5%, the amount of deinking agent is 0.8-1.2% of the mass of the mixed raw materials, and the amount of sodium hydroxide is 1.3-1.7% of the mass of the mixed raw materials.
3. The method for preparing a paper-plastic composite paper for woven bags according to claim 2, characterized in that: In step 3), during the screening and slag removal process, the refined pulp is diluted to a pulp mass concentration of 1.0-1.3%, and then centrifugation, slag removal, filtration, and foaming deinking are performed sequentially.
4. The method for preparing a paper-plastic composite paper for woven bags according to claim 3, characterized in that: In step 3), during the foaming deinking process, 0.8-1.2% of the mass of the mixed raw materials of the deinking agent is added to the slurry, air is injected to generate a large number of bubbles, the foam is scraped off, and the deinking is completed.
5. The method for preparing a paper-plastic composite paper for woven bags according to claim 4, characterized in that: In step 3), the mass concentration of the refined pulp obtained after pulping is 3.5-4.5%, the wet weight is 6.0-8.0, and the freeness is 37-39°SR.
6. The method for preparing a paper-plastic composite paper for woven bags according to claim 5, characterized in that: In step 4), the amount of sizing agent is 0.1-0.2% of the mass of the mixed raw materials, and the amount of wet strength agent is 1.6-1.8% of the mass of the mixed raw materials.
7. The method for preparing a paper-plastic composite paper for woven bags according to claim 6, characterized in that: The sizing agent is AKD sizing agent, and the wet strength agent is PAE wet strength agent.
8. A method for preparing a paper-plastic composite paper for woven bags according to any one of claims 6 or 7, characterized in that: In step 4), during web forming, the web concentration is controlled at 0.6-0.9%, the pulp-to-web speed ratio at 0.95-1.00 (total pressure head), the lip opening at 18-21 mm, and the dryness of the web exit section at 19-22%. During press dewatering, the pressure of the first press line is controlled at 3.5 BAR, the pressure of the second press line at 3.5-4.0 BAR, the pressure of the third press line at 3.0-3.5 BAR, and the dryness of the press exit section at 42-47%. During drying, the steam pressure of the first cylinder is controlled at 0.3-0.5 BAR, the steam pressure of the second cylinder at 0.6-0.9 BAR, the steam pressure of the third cylinder at 1.2-1.5 BAR, and the moisture content of the paper exiting the drying cylinder is 7.5-9.5%.
9. The method for preparing a paper-plastic composite paper for woven bags according to claim 8, characterized in that: In step 5), the plastic layer is a polypropylene flat filament woven fabric.
10. A paper-plastic composite paper for woven bags, characterized in that: It is prepared by the method for preparing paper-plastic composite paper for woven bags according to any one of claims 1-9.