Recycled paper and preparation method thereof

Abstract

The invention discloses recycled paper and a preparation method thereof. The preparation method comprises the following steps: cutting disinfected waste textiles into cotton cloth with the length and the width of 1mm-3mm respectively; adding water and soaking at normal temperature; dissociating to obtain cotton pulp, and boiling the pulp in a water bath; polyoxyethylene with the final concentration of 0.02 wt%-0.05 wt% is added into the cotton pulp, and stirring is conducted; then adding polyvinyl alcohol with the final concentration of 0.05 wt%-0.1 wt%, and stirring; papermaking and pressurizing; and drying to obtain the recycled paper. The recycled paper prepared by the method disclosed by the invention has unique texture and touch feeling, is rich in color, is remarkably better in tensile strength and air permeability compared with conventional handmade paper prepared by taking wood pulp fiber as a raw material, can be applied to the fields of art packaging and the like, and has a good market prospect. A large amount of textile waste in the current market is fully utilized, the problem of shortage of papermaking raw materials is effectively relieved, and the method is energy-saving and environment-friendly.

Description

[0001] This invention claims the priority of a Chinese patent application titled "A Recycled Paper Derived from Waste Cotton Textiles and Its Preparation Method" with the application number 2024118829592, which was filed with the Chinese Patent Office on December 19, 2024. The entire content of this application is incorporated herein by reference. Technical Field

[0002] This invention belongs to the field of papermaking and relates to the technology of recycled paper. More specifically, it relates to a recycled paper derived from waste cotton or cotton blend textiles and its preparation method. Background Art

[0003] Traditional paper production mainly relies on primary fiber raw materials such as wood, which not only leads to the overconsumption of forest resources but also brings problems such as high energy consumption and high pollution. With the increasing global emphasis on environmental protection and sustainable development, the production technology of recycled paper has gradually become an important development direction in the papermaking industry. However, the raw materials currently used for recycled paper are basically common papermaking raw materials such as processed pulp, unprocessed pulp, and existing paper base paper. Although it reduces energy consumption and environmental pollution to a certain extent, it still fails to fundamentally solve the problem.

[0004] For example, CN116770628A discloses a method for preparing a para-aramid / polyphenylene sulfide composite paper and its recycling. This method involves wet grinding of waste aramid fiber / polyphenylene sulfide composite paper to obtain fibrillated aramid fibers, and then using aramid short fibers, polyphenylene sulfide ultrafine fibers, and fibrillated aramid fibers for wet papermaking, followed by hot pressing to prepare a mixed para-aramid / polyphenylene sulfide composite paper. This method only reprocesses the paper for utilization in the original field.

[0005] CN107354810A discloses a method for preparing a wet-pressed paper-plastic pharmaceutical packaging liner. This method uses sugarcane pulp, bamboo pulp, and wood pulp as basic raw materials, and after uniform mixing, hot pressing and shaping, and disinfection and storage, it is prepared into a pharmaceutical packaging box liner. The raw materials used in this method are sugarcane pulp, bamboo pulp, and wood pulp, which still cause energy consumption and environmental pollution.

[0006] CN108252156A discloses a digital thermal transfer paper for recycled paper coating and its preparation method. This method mainly uses polyvinyl alcohol, carboxymethyl cellulose (CMC), titanium dioxide, starch and silicone defoamer. The main steps are as follows: First, polyvinyl alcohol, carboxymethyl cellulose (CMC), titanium dioxide and starch are respectively placed in different containers and mixed with water for reaction. Then, the four prepared solutions are mixed with silicone defoamer in a specific proportion to form a coating glue. Finally, the prepared coating glue is applied to the raw paper through a back glue roller, and after drying, the digital thermal transfer paper for recycled paper coating is obtained. The raw paper used in this method is also the commonly used pulp fiber.

[0007] CN117026669A discloses a production method of an environmentally friendly shopping bag paper. The main raw materials of this method are softwood pulp, hardwood pulp, regenerated cellulose fiber and carboxylated styrene-butadiene latex. The main steps are as follows: The bleached chemical softwood pulp, bleached chemical hardwood pulp and regenerated cellulose fiber are mixed evenly in a mixing pulp tank, and after passing through a pressure screen, AKD sizing agent and cationic polyacrylamide are added, then formed by papermaking, and then dried to ≤5%. The surface sizing is carried out with a carboxylated styrene-butadiene latex mixture, and then dried to 4 - 6%. The raw materials used in this method are also the commonly used wood pulp for papermaking.

[0008] CN117071311A discloses a recycled paper processing technology. The main principle of this technology is to convert the paper scraps generated during the shredding process of recycled waste paper into pulp and then make paper. The main steps are as follows: First, the waste paper generated in the office is stacked and sent into a decomposition box, then the paper is shredded by multiple groups of extrusion and cutting components, then the shredded paper scraps are sorted, and finally some paper scraps are collected for pulping treatment, and dehydrated to obtain recycled paper. The raw material of this technology is still the commonly used papermaking pulp.

[0009] CN117626694A discloses a high-strength paper and its preparation method. The main raw material of this method is composed of plant fibers of corrugated paper pulp. The main steps are as follows: The corrugated paper pulp is made into recycled paper, then the obtained recycled paper is infiltrated with a small amount of alkali-urea mixed solution, taken out after standing at low temperature for a certain time, washed with water and dried. Finally, the treated paper is soaked in a strong alkali solution, taken out after a certain time, washed with water and dried to obtain high-strength paper. The raw material of this method is the commonly used plant fiber for papermaking.

[0010] CN117026687A discloses a preparation method of a self-heat-sealing antibacterial natural color food packaging paper. The raw materials of this method are renewable eucalyptus, sodium alginate, kaolin powder, polyethylene glycol, dodecyl alcohol ester, xanthan gum, konjac glucomannan, glycerol, carrageenan, chitosan solution. The raw materials used in this method are the commonly used wood pulp for papermaking.

[0011] CN106320044A discloses a method for recycling wax-containing waste paper in papermaking. The main raw material of this method is wax-containing waste paper. Through secondary cleaning, the dirt attached to the waste paper is deeply removed, so that the surface of the newly made wax paper is clean without any impurities or variegated colors. This invention only aims at removing the dirt attached inside the paper, and the used raw material, wax-containing waste paper, is made of common papermaking fibers.

[0012] Currently, there are also some reports on preparing recycled paper from waste textile fibers. For example, CN103147337A discloses a method for preparing paper from waste textile fibers. The waste textile fibers are sorted, opened, and ground into fine fibers by a disk refiner, then modified with NaOH solution, PVA solution is added, and then the slurry is prepared, the paper sheet is formed, and high-temperature and high-pressure treatment is carried out. Such as CN115897279A discloses a method for preparing a nano-composite recycled paper based on waste cotton textiles. The waste cotton textiles are recycled, then opened into cotton fibers and all recovered. Then, TEMPO oxidation method is used to prepare cellulose nanofibers from the waste cotton that cannot be recycled during the opening process. The recovered cotton fibers are physically processed into cotton short fibers, and a uniformly mixed cellulose nanofiber / cotton fiber mixed pulp is prepared. Finally, the nano-composite recycled paper is prepared by wet forming and hot pressing processes in sequence. In the article "Basic Research on the Application of Waste Textile Fibers in Papermaking", after the waste textile fibers are opened, they are bleached with NaOH solution / H2O2 solution / CIO2 solution, and then wood pulp fibers are mixed with the waste textile fibers, and the paper is made by machine. The mechanical properties of the paper prepared by mixing wood pulp fibers and waste textile fibers and the recycled paper prepared from waste textile fibers in this article are far inferior to those of the paper prepared from wood pulp fibers. It can be seen that the existing methods for recycling waste textiles into recycled paper currently have high process energy consumption when treating waste fabrics, and all use chemical treatment methods for the recycled fibers after opening, accompanied by the generation of a large amount of chemical sewage, and the performance of the prepared recycled paper is not ideal. Summary of the Invention

[0013] Based on this, the purpose of the present invention is to provide a method for preparing recycled paper from waste cotton / cotton blend textiles, which has low energy consumption, is environmentally friendly, and the prepared recycled paper has high tensile strength.

[0014] The technical solutions to achieve the above purpose are as follows.

[0015] In the first aspect of the present invention, a method for preparing recycled paper is provided, including the following steps:

[0016] Step 1: Cut the waste textiles after anhydrous disinfection treatment into cotton cloth with a length and width of 1 mm to 3 mm respectively; the waste textiles are waste cotton textiles or waste cotton blend textiles;

[0017] Step 2: Add water to the cotton cloth described in Step 1 in a weight ratio of 1:300 - 400, and soak at room temperature for 10h - 12h;

[0018] Step 3: Dissociate to obtain cotton pulp; perform a water bath treatment on the cotton pulp;

[0019] Step 4: Add polyethylene oxide with a final concentration of 0.02wt% - 0.05wt% to the cotton pulp and stir; then add polyvinyl alcohol with a final concentration of 0.05wt% - 0.1wt% and stir;

[0020] Step 5: Sheet forming, apply pressure;

[0021] Step 6: Dry to obtain the recycled paper.

[0022] In the second aspect of the present invention, there is provided the recycled paper obtained by the above preparation method.

[0023] In the present invention, the recycled waste cotton / cotton blended textiles are disinfected, physically shredded and then soaked, and then dissociated into single fiber state to obtain cotton pulp, and then subjected to water bath pulping. Then, appropriate amounts of separating agent polyethylene oxide (PEO) and binder polyvinyl alcohol (PVA) are added inside the cotton pulp, and then sheet forming, pressure application and drying are carried out, successfully preparing the recycled paper from recycled fibers of waste cotton / cotton blended textiles. Moreover, the prepared recycled paper has a unique texture, rich colors, can be used in fields such as art packaging, and has good market prospects.

[0024] In the preparation process of the recycled paper of the present invention, on the one hand, physical opening and dissociation techniques are used to replace high - energy - consuming disc refiners and high - temperature and high - pressure equipment, and the energy consumption of the equipment used throughout the papermaking process is significantly reduced compared with the existing methods. On the other hand, chemical bleaching (NaOH / H2O2 / CIO2), TEMPO oxidation and other chemical treatment methods are abandoned, and polyvinyl alcohol (PVA) and polyethylene oxide (PEO) with appropriate concentrations are used as manual papermaking aids. This can not only improve fiber uniformity, fiber interweaving degree and paper strength, but also their water solubility enables them not to use organic solvents during the papermaking process, so that the original color of the discarded clothes can be retained, and recycled paper with various colors can be prepared, reducing the comprehensive energy consumption and sewage toxicity.

[0025] The present invention provides a method for reusing a large number of discarded cotton fabrics on the market by using waste cotton / cotton blended textiles as raw materials and re - empowering the papermaking industry, which makes full use of a large number of textile waste on the current market and effectively alleviates the problem of shortage of papermaking raw materials in China.

[0026] In addition, the method for preparing recycled paper according to the present invention does not require complex machinery. Ordinary workers can master the core processes after short-term training, and it is suitable for decentralized production in rural workshops or small-scale environmental protection workshops. The present invention realizes for the first time the low technical threshold for recycling waste cotton textile fibers into paper, and its products can replace part of the wood pulp paper in fields such as cultural and creative paper and packaging liner paper, with both environmental protection and social and economic benefits. Description of the Drawings

[0027] Figure 1 In Example 1 of the present invention, the cotton cloth was cut transversely or longitudinally to 1 mm.

[0028] Figure 2 In Example 1 of the present invention, the cotton cloth was cut transversely and longitudinally to 1 mm respectively.

[0029] Figure 3 The cotton pulp obtained after dissociating the cotton cloth in Example 1 of the present invention.

[0030] Figure 4 The recycled paper prepared in Example 1 of the present invention.

[0031] Figure 5 The recycled paper prepared in Example 2 of the present invention.

[0032] Figure 6 The recycled paper prepared in Example 3 of the present invention.

[0033] Figure 7 The recycled paper prepared in Example 4 of the present invention.

[0034] Figure 8 The recycled paper prepared in Example 5 of the present invention.

[0035] Figure 9 The recycled paper prepared in Example 6 of the present invention.

[0036] Figure 10 The recycled paper prepared in Comparative Example 1 of the present invention.

[0037] Figure 11 The recycled paper prepared in Comparative Example 2 of the present invention.

[0038] Figure 12 The recycled paper prepared in Comparative Example 3 of the present invention.

[0039] Figure 13 The recycled paper prepared in Comparative Example 4 of the present invention.

[0040] Figure 14 The recycled paper prepared in Comparative Example 5 of the present invention.

[0041] Figure 15The recycled paper prepared in Comparative Example 6 of the present invention. Detailed implementation manners

[0042] The technical solutions of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0043] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the description of the present invention are only for the purpose of describing specific embodiments and are not used to limit the present invention.

[0044] The terms "include" and "have" in the present invention and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, device, product or equipment that includes a series of steps is not limited to the listed steps or modules, but optionally further includes steps not listed, or optionally further includes other steps inherent to these processes, methods, products or equipment.

[0045] "Plurality" mentioned in the present invention means two or more. "And / or" describes the association relationship of associated objects and indicates that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. The character " / " generally represents an "or" relationship between the front and rear associated objects.

[0046] In some embodiments of the present invention, a method for preparing recycled paper is disclosed, including the following steps:

[0047] Step 1: Perform anhydrous disinfection treatment on the recycled waste cotton / cotton blended textiles.

[0048] Step 2: Cut the waste cotton textiles into cotton cloth with a length and width of 1 mm to 3 mm respectively.

[0049] Step 3: Add water to the cotton cloth in Step 2 according to a weight ratio of 1:300 to 400, and soak at room temperature for 10 h to 12 h.

[0050] Step 4: Dissociate to obtain cotton pulp.

[0051] Step 5: Perform water bath heating and pulping treatment on the cotton pulp.

[0052] Step 6: Add PEO with a final concentration of 0.02 wt% - 0.05 wt% to the cotton pulp (using an appropriate concentration of PEO as a dispersant can prevent fiber entanglement during papermaking, promote the uniform dispersion of fibers in water, reduce flocculation, and thus facilitate the preparation of recycled paper), and stir; then add PVA with a final concentration of 0.05 wt% - 0.1 wt% (using an appropriate concentration of PVA as a binder can well adhere single fibers together, and thus facilitate the preparation of recycled paper), and stir;

[0053] Step 7: After papermaking (using an ancient method of scooping with a paper-making curtain and combining the traditional manual bamboo paper "swinging the curtain into the pulp" technique), apply pressure;

[0054] Step 8: Dry to obtain recycled paper.

[0055] In some of the embodiments, Step 1 includes: evenly laying the waste cotton / cotton blended textiles flat on the conveyor belt of the ultraviolet disinfection machine, feeding them into the box part of the ultraviolet disinfection machine, and irradiating with UV-C light at an irradiation level of 20000 μJ / cm 2 ~25000 μJ / cm 2 for 30 min - 60 min, which can achieve a killing rate of more than 90% of bacteria and microorganisms on the discarded clothing.

[0056] In some of the embodiments, Step 2 includes: evenly arranging the waste cotton / cotton blended textiles in the same direction, feeding them into a TC cutting machine for cutting, performing a longitudinal cut of 1 mm (or 2 mm or 3 mm) and a transverse cut of 1 mm (or 2 mm or 3 mm). By transverse and longitudinal cutting, small pieces of cotton cloth with lengths and widths both in the range of 1 mm - 3 mm are obtained, which can basically perform preliminary fragmentation treatment on the waste cotton / cotton blended textiles recycled in the market, greatly facilitating the next dissociation.

[0057] In some of the embodiments, in Step 2, the waste cotton / cotton blended textiles are cut into cotton cloth with lengths and widths of 1 mm - 2 mm respectively.

[0058] In some of the embodiments, in Step 3, the weight ratio of the cotton cloth to water is 1:300 - 350.

[0059] In some of the embodiments, in Step 3, the weight ratio of the cotton cloth to water is 1:310 - 330.

[0060] In some of the embodiments, Step 4 includes: using a fiber dissociator to dissociate into single fibers to obtain cotton pulp; the dissociation parameters are 30000 revolutions - 50000 revolutions, and the rotation speed is 1000 revolutions per minute - 3600 revolutions per minute. Appropriate dissociation parameters can disperse the knotted cotton fiber bundles into single fibers, which play a crucial role in the successful preparation of recycled paper.

[0061] In some of these embodiments, the dissociation parameter is 30,000 to 40,000 revolutions, and the rotational speed is 3,000 to 3,600 revolutions per minute.

[0062] In some of these embodiments, in step five, the temperature of the water bath is 70°C to 85°C, and the time of the water bath is 1 h to 1.5 h.

[0063] In some of these embodiments, in step six, the final concentration of PEO is 0.03 wt% to 0.05 wt%.

[0064] In some of these embodiments, in step six, the final concentration of PVA is 0.05 wt% to 0.08 wt%.

[0065] In some of these embodiments, step seven includes: after papermaking with a papermaking frame is completed, a pressure of 675 Pa to 835 Pa is applied to the paper.

[0066] In some of these embodiments, step eight includes: putting it into a dryer and drying at 40°C to 75°C.

[0067] In some of these embodiments, the drying time is 4 h to 8 h.

[0068] In some of these embodiments of the present invention, recycled paper from waste cotton textiles obtained by the above preparation method is disclosed.

[0069] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0070] Example 1 Preparation method of recycled paper from waste cotton textiles

[0071] It includes the following steps:

[0072] 1. Disinfect the recycled waste cotton textiles

[0073] (1) Sort the recycled waste cotton textiles, place them in the same direction, and send them into an ultraviolet disinfection machine (FS-0685, Suzhou Fansi Instrument Equipment Co., Ltd.) to make them as evenly distributed as possible on the conveyor belt of the ultraviolet disinfection machine.

[0074] (2) Adjust the parameters of the ultraviolet disinfection machine to UV-C light source 235, which emits germicidal light of 254 nm, and irradiate at an irradiation level of 25,000 μJ / cm 2 ².

[0075] (3) Start the machine. After the waste cotton textiles are sent into the ultraviolet disinfection box through the conveyor belt and into the feeding port, stop the transportation of the conveyor belt and stay for irradiation for 45 minutes.

[0076] (4) After the irradiation is completed, start the conveyor belt and collect the disinfected waste cotton textiles at the discharge port.

[0077] 2. Cut the disinfected waste cotton textiles

[0078] (1) Sort the disinfected waste cotton fabric, place it in the same direction, and send it into the TC cutting machine (ZD220 of Shandong Tongchen Co., Ltd.) for cutting, so that it is evenly distributed on the conveyor belt of the cutting machine as much as possible.

[0079] (2) Adjust the cutting machine parameters to a cutting distance of 1 mm.

[0080] (3) Start the machine. After sending the sorted fabric into the inlet of the cutting machine through the conveyor belt, collect the fabric processed in the first cutting direction (horizontal) at the discharge port ( Figure 1 ).

[0081] (4) For the fabric collected and processed in the first cutting direction, repeat the above steps 1, 2, and 3, and collect the fabric processed in the two cutting directions (horizontal and vertical) at the discharge port. Finally, obtain small pieces of cotton fabric with a longitudinal cutting length of 1 mm and a transverse cutting length of 1 mm ( Figure 2 ).

[0082] 3. Dissociate the cotton fabric

[0083] (1) According to the weight ratio of water:cotton fabric = 300:1, soak the cut and processed cotton fabric (10 g) in water (3000 g) at room temperature overnight (10 - 12 h);

[0084] (2) Dissociate the soaked cotton fabric with a fiber dissociator (CV-SJ-B of Dongguan Xiwaka Precision Measuring Instrument Co., Ltd.), and the dissociation parameter is 3 w revolutions, with a rotation speed of 3000 revolutions per minute, so as to obtain cotton pulp mixed with single-bundle cotton fiber state cotton fiber and water ( Figure 3 ).

[0085] 4. Water bath treatment

[0086] Heat and cook the cotton pulp with a water bath pot. The water bath temperature is 70 °C and the water bath time is 1 h.

[0087] 5. Handmade paper making

[0088] (1) Add PEO (polyethylene oxide, Sumitomo of Japan, model: PFZ blue, molecular weight: 7.5 million) with a final concentration of 0.02 wt% (0.602 g) to the cotton pulp (3010 g), and continuously stir the solution during the addition process to make it evenly mixed.

[0089] (2) Then add PVA (polyvinyl alcohol, Shanghai Chenqi Chemical Technology Co., Ltd., model: cold-soluble 2688, molecular weight: 114400 - 123200) with a final concentration of 0.05 wt% (1.505 g) to the cotton pulp (3010 g). During the addition process, continuously stir the solution to make it evenly mixed, obtaining the pulp.

[0090] (3) Use a papermaking frame of A5 size for sheet forming. Apply a pressure of 675 Pa on the paper until there is no obvious filtrate.

[0091] (4) Put it into a drying oven and dry for 6 h, setting the drying oven temperature at 65 °C.

[0092] (5) After the paper is dried, take it out of the frame, and then the recycled paper is obtained (as Figure 4 ).

[0093] The recycled paper prepared in this example has a unique wrinkled texture and a soft touch on the paper surface, can be used in fields such as art packaging, and has good market prospects.

[0094] Example 2

[0095] This example provides a method for preparing recycled paper. Except that in the manual sheet forming step (1), add PEO with a final concentration of 0.05 wt% (1.505 g) to the cotton pulp (3010 g), other operations are the same as in Example 1.

[0096] The recycled paper prepared in this example is as Figure 5 shown. The recycled paper has a unique wrinkled texture and a soft touch on the paper surface.

[0097] Example 3

[0098] This example provides a method for preparing recycled paper. Except that in the manual sheet forming step (1), add PVA with a final concentration of 0.1 wt% (3.01 g) to the cotton pulp (3010 g), other operations are the same as in Example 1.

[0099] The recycled paper prepared in this example is as Figure 6 shown. The recycled paper has a unique wrinkled texture and a soft touch on the paper surface.

[0100] Example 4

[0101] This embodiment provides a method for preparing recycled paper. Except in the step of dissociating cotton cloth, green cotton cloth (waste cotton blended textiles, cut into small pieces of cotton cloth with a length and width of 1 mm × 1 mm according to the method of Example 1) and black cotton cloth (waste cotton blended textiles, cut into small pieces of cotton cloth with a length and width of 1 mm × 1 mm according to the method of Example 1) are evenly mixed in a ratio of 7:3 (7 g of green cotton cloth and 3 g of black cotton cloth), and then water is added for soaking. Other operations are the same as those in Example 1.

[0102] The recycled paper prepared in this embodiment is as Figure 7 shown. The recycled paper has a unique wrinkled texture and a soft touch on the paper surface, and also has a special color due to the color of the cotton fibers used.

[0103] Example 5

[0104] This embodiment provides a method for preparing recycled paper. Except in the step of dissociating cotton cloth, white cotton fibers (cut into small pieces of cotton cloth with a length and width of 1 mm × 1 mm according to the method of Example 1) and green cotton fibers (cut into small pieces of cotton cloth with a length and width of 1 mm × 1 mm according to the method of Example 1) are evenly mixed in a ratio of 1:1 (5 g each), and then water is added for soaking. Other operations are the same as those in Example 1.

[0105] The recycled paper prepared in this embodiment is as Figure 8 shown. The recycled paper has a unique wrinkled texture and a soft touch on the paper surface, and also has a special color due to the color of the cotton fibers used.

[0106] Example 6

[0107] This embodiment provides a method for preparing recycled paper. Except in the step of dissociating cotton cloth, pulp (long fiber dehydrated pulp, mainly composed of fiber of trees such as Broussonetia papyrifera, with a length distribution of 2 - 3 mm, and the manufacturer is Lexiuzhibao Co., Ltd. in Jinan, Shandong) and cotton cloth (cut into small pieces of cotton cloth with a length and width of 1 mm × 1 mm according to the method of Example 1) are evenly mixed in a ratio of 1:1 (5 g each), and then water is added for soaking. Other operations are the same as those in Example 1.

[0108] This embodiment can also successfully prepare recycled paper using pulp and cotton cloth. As Figure 9 shown, the recycled paper has a unique wrinkled texture and a soft touch on the paper surface.

[0109] Performance Test

[0110] Tensile strength measurements (using the GB / T 1291-2018 standard, instrument: hand-cranked vertical testing machine, model: ZP-100N, manufacturer: Shenzhen Ailigong Instruments Co., Ltd.) and air permeability measurements (using the GB / T 5453-1997 standard, instrument: fully automatic air permeability tester, model: YD-TQD-A, manufacturer: Guangdong Yunda Machinery Equipment Manufacturing Co., Ltd.) were carried out on the recycled paper and pulp fiber handmade paper of Example 1, Example 4, and Example 6 (prepared from long fiber dehydrated pulp purchased from Lexiu Zhibao Co., Ltd., Jinan, Shandong according to the method of Example 1). The results are shown in Table 1.

[0111] Table 1

[0112] Tensile strength (kN / m) Air permeability (mm / s) Example 1 1.469 428.0 Example 4 1.527 436.0 Example 6 1.405 222.5 Handmade paper of wood pulp fiber 1.380 38.2

[0113] From the results in Table 1, it can be seen that compared with the pulp fiber handmade paper prepared from long fiber dehydrated pulp, the recycled paper prepared from waste cotton textiles, waste cotton blended textiles, and the mixture of waste cotton textiles and long fiber dehydrated pulp (Example 1, Example 4, and Example 6 respectively) has significantly better tensile strength and air permeability performance.

[0114] Comparative Example 1

[0115] This comparative example provides a method for preparing recycled paper. Except that in the manual papermaking step (2), PVA with a final concentration of 0.15 wt% (4.515 g) was added to the cotton pulp (3010 g), other operations were the same as in Example 1.

[0116] The recycled paper prepared in this comparative example is as Figure 10 shown. Due to the overly loose structure, the paper was directly damaged during the process of being removed from the frame. We analyzed that the reason might be that the PVA concentration was too high, the pulp viscosity was too high, and the fibers adhered and agglomerated seriously, which would lead to an overly loose paper structure, and the paper would break and could not form paper. Moreover, too much PVA would cause the excess glue to turn the paper yellow after drying.

[0117] Comparative Example 2

[0118] This comparative example provides a method for preparing recycled paper. Except that in the manual papermaking step (2), PEO with a final concentration of 0.1 wt% (3.01 g) was added to the cotton pulp (3010 g), other operations were the same as in Example 1.

[0119] The recycled paper prepared in this comparative example is as Figure 11As shown in the figure, the paper is directly damaged during the unframing process due to its loose structure. We analyzed that the reason may be that the PEO concentration is too high, the fibers are over-dispersed, the fibers cannot adhere well, and there is still excessive unmelted PEO on the surface of the paper. When drying, the unmelted PEO stays on the surface of the paper, causing transparent pits on the surface of the paper, and the paper structure is looser and easier to break.

[0120] Comparative Example 3

[0121] This comparative example provides a method for preparing recycled paper. Except that the recycled waste cotton textiles are cut into small pieces of cotton cloth with a longitudinal length of 4 mm and a transverse length of 4 mm, other operations are the same as those in Example 1.

[0122] The method of this comparative example cannot produce recycled paper. Figure 12 We analyzed that the possible reason is that after cutting, when the length and width of the cotton cloth are too long, the area of ​​the cotton cloth is too large, resulting in the blade of the fiber separator being unable to separate part of the cotton cloth, and there are a large number of blocky cotton cloth in the cotton pulp, which makes it impossible to separate the cotton cloth in the form of single fibers during hand-made papermaking, but in the form of blocks on the paper, resulting in loose entanglement between fibers, loose structure, and ultimately failure to form paper.

[0123] Comparative Example 4

[0124] This comparative example provides a method for preparing recycled paper. Except that the dissociation parameter is 2w revolutions when dissociating the cotton cloth, other operations are the same as those in Example 1.

[0125] The recycled paper prepared in this comparative example is Figure 13 As shown, from Figure 13 It can be seen that the surface of recycled paper has uneven bulges. We analyzed that the reason may be that the number of revolutions used when dissociating the cotton cloth is insufficient, and there is some undissociated cotton cloth in the cotton pulp. When hand-made paper is made, it cannot exist in the paper as a single fiber, resulting in uneven bulges on the paper surface.

[0126] Comparative Example 5

[0127] This comparative example provides a method for preparing recycled paper. Except that the cotton cloth dissociation step is not performed, other operations are the same as those in Example 1.

[0128] The method of this comparative example cannot be used to prepare recycled paper, and its surface is formed by squeezing small pieces of cotton cloth, such as Figure 14 We analyzed that the reason is that the cotton cloth was not dissociated, so it could not be in a single fiber state during papermaking. The cotton fibers in the bundled small pieces of cotton cloth could not be entangled, resulting in a loose paper structure, damaged paper, and no use value.

[0129] Comparative Example 6

[0130] This comparative example provides a method for preparing recycled paper. Except that in the manual papermaking step (2), a plant papermaking glue with a final concentration of 0.05 wt% (1.505 g) (manual papermaking binder: plant rhizome extract, purchased from Anhui Time Creation Culture Technology Co., Ltd.) was added to the cotton pulp (3010 g), all other operations were the same as in Example 1.

[0131] The recycled paper prepared in this comparative example is as Figure 15 shown. It can be seen from Figure 15 that the surface fibers of the recycled paper are severely stacked, the paper surface has obvious textures, and many cotton fibers are loosely distributed on the surface and can fly out of the paper surface directly.

[0132] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0133] The above-described embodiments only represent several implementation manners of the present invention, and the description is relatively specific and detailed. However, it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent should be subject to the appended claims.

Claims

1. A method for preparing recycled paper, characterized in that: The following steps are involved: Step 1: chopping the waste textiles after waterless disinfection into cotton cloth with a length and width of 1 mm to 3 mm respectively; the waste textiles are waste cotton textiles or waste cotton blended textiles; Step 2: Add water to the cotton cloth in step 1 at a weight ratio of 1:300-400, and soak at room temperature for 10h-12h; Step 3: dissociate to obtain cotton pulp; subject the cotton pulp to water bath treatment; Step 4: adding polyethylene oxide with a final concentration of 0.02 wt% to 0.05 wt% to the cotton pulp, stirring; then adding polyvinyl alcohol with a final concentration of 0.05 wt% to 0.1 wt%, stirring; Step 5: paper making and pressurizing; Step 6: Drying to obtain recycled paper.

2. The preparation method according to claim 1, characterized in that: In step 1, the waterless disinfection treatment comprises the steps of: subjecting the waste textiles to 20000 μJ / cm 2 ~25000μJ / cm 2 Irradiate under UV-C light for 30min to 60min; And / or, the waste textiles are shredded into cotton cloth having a length and a width of 1 mm to 2 mm respectively.

3. The preparation method according to claim 1, characterized in that: Step one includes: placing the waste textiles evenly in the same direction, feeding them into a cutting machine for cutting, wherein the longitudinal cutting length is 1mm-3mm, and the transverse cutting length is 1mm-3mm.

4. The preparation method according to claim 1, characterized in that: In step 2, the weight ratio of the cotton cloth to water is 1:300-350, preferably 1:310-330.

5. The preparation method according to claim 1, characterized in that: Step three includes: using a fiber disintegrator to dissociate into a single fiber state to obtain cotton pulp; the dissociation parameters are 3w rpm to 5w rpm and a rotation speed of 1000 rpm to 3600 rpm; And / or, the temperature of the water bath is 70° C. to 85° C., and the time of the water bath is 1 h to 1.5 h.

6. The preparation method according to claim 5, characterized in that: The dissociation parameters are 3w rpm to 4w rpm and a rotation speed of 3000 rpm to 3600 rpm.

7. The preparation method according to claim 1, characterized in that: In step 4, the final concentration of PEO is 0.03wt% to 0.05wt%; and / or the final concentration of PVA is 0.05wt% to 0.08wt%.

8. The preparation method according to claim 1, characterized in that: In step 5, the pressurization pressure is 675Pa to 835Pa, and the pressurization is performed until no obvious filtrate is left.

9. The preparation method according to claim 1, characterized in that: Step six comprises: placing in a dryer and drying at 40° C. to 75° C.; preferably, the drying time is 4 hours to 8 hours.

10. Recycled paper derived from waste cotton textiles obtained by the preparation method according to any one of claims 1 to 9.

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