Recycled paper and preparation method thereof

Abstract

The present invention discloses a recycled paper and a preparation method thereof. The steps include: shredding sterilized waste textiles into cotton cloth with a length and width of 1 mm to 3 mm; adding water and soaking at room temperature; dissociating to obtain cotton pulp, and boiling the pulp in a water bath; adding polyethylene oxide with a final concentration of 0.02 wt% to 0.05 wt% to the cotton pulp, and stirring; then adding polyvinyl alcohol with a final concentration of 0.05 wt% to 0.1 wt% and stirring; making paper, applying pressure, and drying to obtain recycled paper. The recycled paper prepared by the method of the present invention has a unique texture and touch, rich colors, and has significantly better tensile strength and air permeability than conventional handmade paper made from wood pulp fibers. It can be used in fields such as art packaging and has good market prospects. The present invention makes full use of the large amount of textile waste currently on the market, effectively alleviates the problem of shortage of papermaking raw materials, and is energy-saving and environmentally friendly.

Description

[0001] The present invention claims priority to the Chinese patent application filed with the Patent Office of China on December 19, 2024, with application number 2024118829592, entitled “A kind of recycled paper derived from waste cotton textiles and its preparation method”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present invention belongs to the field of papermaking and relates to the technology of recycled paper, and more particularly to recycled paper sourced from waste cotton or cotton blended textiles and a preparation method thereof. Background Art

[0003] Traditional paper production primarily relies on raw materials like wood. This not only leads to excessive depletion of forest resources but is also associated with high energy consumption and pollution. With the increasing global emphasis on environmental protection and sustainable development, recycled paper production technology has become a key development direction for the papermaking industry. However, the raw materials currently used for recycled paper are generally common papermaking raw materials, such as treated pulp, untreated pulp, and existing paper bases. While this reduces energy consumption and environmental pollution to some extent, it still fails to fundamentally address the problem.

[0004] For example, CN116770628A discloses a para-aramid / polyphenylene sulfide composite paper and a method for its regeneration. This method involves wet-grinding discarded aramid fiber / polyphenylene sulfide composite paper to produce fibrillated aramid fibers. This is then wet-laid using chopped aramid fibers, ultrafine polyphenylene sulfide fibers, and fibrillated aramid fibers, followed by hot pressing to produce the mixed para-aramid / polyphenylene sulfide composite paper. This method merely reprocesses the paper back into its original field for reuse.

[0005] CN107354810A discloses a method for preparing wet-pressed paper-plastic pharmaceutical packaging liners. This method uses sugarcane pulp, bamboo pulp, and wood pulp as basic raw materials. The raw materials are uniformly mixed, hot-pressed, shaped, sterilized, and stored to produce the pharmaceutical packaging lining. This method, which uses sugarcane pulp, bamboo pulp, and wood pulp as raw materials, still results in energy consumption and environmental pollution.

[0006] CN108252156A discloses a recycled papermaking coated digital thermal transfer paper and its preparation method. The method primarily utilizes polyvinyl alcohol, carboxymethyl cellulose (CMC), titanium dioxide, starch, and an organic silicon defoamer. The main steps are: first, polyvinyl alcohol, carboxymethyl cellulose (CMC), titanium dioxide, and starch are placed in separate containers and mixed with water for reaction; then, the four resulting solutions are mixed with an organic silicon defoamer in a specific ratio to form a coating glue; finally, the resulting coating glue is applied to raw paper using a backing roller; and after drying, the recycled papermaking coated digital thermal transfer paper is obtained. The raw paper used in this method is also commonly used pulp fiber.

[0007] CN117026669A discloses a method for producing environmentally friendly handbag paper. The main raw materials of this method are softwood pulp, hardwood pulp, regenerated cellulose fiber and carboxyl styrene butadiene latex. The main steps are to uniformly mix bleached chemical softwood pulp, bleached chemical hardwood pulp and regenerated cellulose fiber in a mixing tank, add AKD sizing agent and cationic polyacrylamide after pressure screening, paper-cut into pieces, then dry to ≤5%, apply surface sizing with carboxyl styrene butadiene latex mixture, and then dry to 4-6%. The raw materials used in this method are also commonly used papermaking wood pulp.

[0008] CN117071311A discloses a recycled paper processing process. The process primarily involves converting scraps of recycled waste paper into pulp for papermaking. The main steps are: first, stacking office waste paper into a decomposition bin; then, multiple extrusion and cutting components shred the paper; then, the resulting scraps are sorted; and finally, some of the scraps are collected for pulping and dehydration to produce recycled paper. The raw material for this process remains conventional papermaking pulp.

[0009] CN117626694A discloses a high-strength paper and a method for producing it. The method uses plant fibers from corrugated paper pulp as the primary raw material. The main steps are: converting the corrugated paper pulp into recycled paper, then soaking the resulting recycled paper in a small amount of an alkaline urea mixed solution, allowing it to stand at low temperature for a certain period of time, then removing it from the paper, washing it, and drying it. Finally, soaking the treated paper in a strong alkaline solution, removing it from the paper after a certain period of time, washing it, and drying it to obtain the high-strength paper. The raw materials for this method are plant fibers commonly used in papermaking.

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

[0011] CN106320044A discloses a method for recycling waxy waste paper into paper. The method uses waxy waste paper as the primary raw material. A secondary cleaning process deeply removes contaminants from the waste paper, leaving the newly produced waxed paper surface clean and free of impurities or discoloration. This invention focuses solely on removing contaminants from paper, and the waxy waste paper used as the raw material is made from commonly used papermaking fibers.

[0012] Currently, there are also some reports on the use of waste textile fibers to produce recycled paper. For example, CN103147337A discloses a method for producing paper from waste textile fibers, which involves sorting, opening, and grinding the waste textile fibers into fine fibers using a disc grinder. The fibers are then modified with a NaOH solution, and a PVA solution is added. A slurry is then prepared, the paper is formed into sheets, and the paper is subjected to high-temperature and high-pressure treatment. For example, CN115897279A discloses a method for producing nanocomposite recycled paper based on waste cotton textiles. The waste cotton textiles are recycled, opened into cotton fibers, and all of them are recovered. The cotton noil that cannot be recycled during the opening process is then converted into cellulose nanofibers using a TEMPO oxidation process. The recovered cotton fibers are then physically treated into short cotton fibers to produce a uniformly mixed cellulose nanofiber / cotton fiber pulp. Finally, the nanocomposite recycled paper is produced through a wet-laid web forming and hot-pressing process. In the article "Basic Research on the Application of Waste Textile Fibers in Papermaking," the waste textile fibers were first opened and then bleached using NaOH solution / H2O2 solution / CIO2 solution. Wood pulp fibers were then mixed with the waste textile fibers and paper was made using a machine. The mechanical properties of the paper made from the mixture of wood pulp fibers and waste textile fibers, as well as the recycled paper made from waste textile fibers, were far inferior to those of the paper made from wood pulp fibers. This shows that the current methods of recycling waste textiles for papermaking consume a lot of energy when processing waste fabrics, and chemical treatment is used to treat the opened recycled fibers, resulting in the generation of large amounts of chemical wastewater. The performance of the recycled paper produced is also unsatisfactory. Summary of the Invention

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

[0014] The technical solutions for achieving the above-mentioned objectives include the following.

[0015] A first aspect of the present invention provides a method for preparing recycled paper, comprising the following steps:

[0016] Step 1: chopping the waste textiles after anhydrous 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;

[0017] 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 10-12 hours;

[0018] Step 3: dissociate to obtain cotton pulp; subject the cotton pulp to water bath treatment;

[0019] Step 4: adding polyethylene oxide to a final concentration of 0.02 wt% to 0.05 wt% to the cotton pulp and stirring; then adding polyvinyl alcohol to a final concentration of 0.05 wt% to 0.1 wt% and stirring;

[0020] Step 5: Papermaking and pressurization;

[0021] Step 6: Drying to obtain recycled paper.

[0022] The second aspect of the present invention provides recycled paper obtained by the above preparation method.

[0023] The present invention disinfects and physically crushes the recycled waste cotton / cotton blended textiles, then soaks them, dissociates them into single fibers, obtains cotton pulp, boils the pulp in a water bath, and then adds appropriate amounts of polyethylene oxide (PEO) as a separator and polyvinyl alcohol (PVA) as a binder into the cotton pulp. The process then proceeds to papermaking, pressurizing, and drying, thereby successfully preparing recycled paper derived from recycled fibers of waste cotton / cotton blended textiles. The recycled paper thus prepared has a unique texture and rich colors, can be used in fields such as art packaging, and has good market prospects.

[0024] The preparation process of recycled paper of the present invention, on the one hand, adopts physical opening and dissociation technology to replace high-energy-consuming disc grinders and high-temperature and high-pressure equipment, and the energy consumption of the equipment used in the entire papermaking process is significantly reduced compared with the existing methods; on the other hand, chemical treatment methods such as chemical bleaching (NaOH / H2O2 / CIO2) and TEMPO oxidation are abandoned, and polyvinyl alcohol (PVA) and polyethylene oxide (PEO) of appropriate concentrations are used as manual papermaking additives, which can not only improve fiber uniformity, fiber interweaving and paper strength, but also their water solubility makes it unnecessary to use organic solvents in the papermaking process, thereby retaining the original color of discarded clothing, thereby preparing recycled paper with various colors, reducing comprehensive energy consumption and wastewater toxicity.

[0025] The present invention provides a method for recycling a large amount of discarded cotton fabrics on the market using waste cotton / cotton blended textiles as raw materials, and re-empowering the papermaking industry. It fully utilizes the large amount of textile waste currently on the market and effectively alleviates the problem of shortage of papermaking raw materials in my country.

[0026] Furthermore, the recycled paper production method of this invention does not require complex machinery; ordinary workers can master the core processes after a short training period. It is suitable for decentralized production in rural workshops or small-scale environmentally friendly workshops. This invention, for the first time, achieves a low-tech barrier to entry for recycled papermaking from waste cotton textile fibers. Its products can partially replace wood pulp paper in areas such as cultural and creative paper and packaging lining, achieving both environmental protection and socioeconomic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 In Example 1 of the present invention, the cotton cloth is cut into 1 mm in the transverse or longitudinal direction.

[0028] Figure 2 In Example 1 of the present invention, the cotton cloth is cut into 1 mm in the transverse and longitudinal directions respectively.

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

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

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

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

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

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

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

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

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

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

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

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

[0041] Figure 15This is the recycled paper prepared in Comparative Example 6 of the present invention. DETAILED DESCRIPTION

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

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

[0044] The terms "comprise," "comprising," and "having," and any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, apparatus, product, or device comprising a series of steps is not limited to the listed steps or modules but may optionally include steps not listed, or other steps inherent to the process, method, product, or device.

[0045] In this application, "plurality" refers to two or more. "And / or" describes the relationship between related objects, indicating that three possible relationships exist. For example, "A and / or B" can mean: A exists alone, A and B exist simultaneously, or B exists alone. The character " / " generally indicates that the related objects are in an "or" relationship.

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

[0047] Step 1: Disinfect the recycled waste cotton / cotton blended textiles with waterless disinfection;

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

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

[0050] Step 4: dissociation to obtain cotton pulp;

[0051] Step 5: heating and boiling the cotton pulp in a water bath;

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

[0053] Step 7: Papermaking (using the ancient method of scooping paper curtains to form paper, combined with the traditional handmade bamboo paper "swinging curtains into pulp" technique) and then pressurizing;

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

[0055] In some embodiments, step 1 includes: evenly laying the waste cotton / cotton blended textiles on the conveyor belt of the UV disinfection machine, feeding them into the UV disinfection machine body, and using UV-C light at 20000 μJ / cm 2 ~25000μJ / cm 2 Irradiation at the irradiation level for 30 minutes to 60 minutes can achieve a killing rate of more than 90% of bacteria and microorganisms on discarded clothing.

[0056] In some embodiments, step 2 includes evenly arranging waste cotton / cotton blended textiles in the same direction and feeding them into a TC cutter 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). The transverse and longitudinal cuts produce small pieces of cotton cloth with a length and width ranging from 1 mm to 3 mm, which essentially performs a preliminary fragmentation process on recycled waste cotton / cotton blended textiles, greatly facilitating the subsequent separation process.

[0057] In some embodiments, in step 2, the waste cotton / cotton blended textiles are chopped into cotton cloths with a length and width of 1 mm to 2 mm respectively.

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

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

[0060] In some embodiments, step 4 includes using a fiber disintegrator to disintegrate the cotton into single fibers to obtain cotton pulp; the disintegration parameters are 3W to 5W rpm and a rotation speed of 1000 to 3600 rpm. Appropriate disintegration parameters can separate tangled cotton fiber bundles into single fibers, which is crucial for the successful production of recycled paper.

[0061] In some embodiments, the dissociation parameter is 3W to 4W rpm, and the rotation speed is 3000 rpm to 3600 rpm.

[0062] In some embodiments, the temperature of the water bath in step 5 is 70° C. to 85° C., and the time of the water bath is 1 h to 1.5 h.

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

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

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

[0066] In some embodiments, step eight includes: placing in a dryer and drying at 40°C to 75°C.

[0067] In some embodiments, the drying time is 4 hours to 8 hours.

[0068] In some embodiments of the present invention, the recycled paper derived from waste cotton textiles obtained by the above-mentioned 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] The following steps are involved:

[0072] 1. Disinfected and recycled waste cotton textiles

[0073] (1) Arrange the recycled waste cotton textiles, place them in the same direction, and send them into the ultraviolet disinfection machine (Suzhou Fansi Instrument Equipment Co., Ltd. FS-0685) so that they are distributed as evenly 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 254nm sterilization light at 25000μJ / cm 2 Exposure to radiation levels.

[0075] (3) Start the machine, and after the waste cotton textiles are fed into the feed port through the conveyor belt and enter the ultraviolet disinfection box, stop the conveyor belt and stay for 45 minutes.

[0076] (4) After the irradiation is completed, the conveyor belt is started to collect the sterilized waste cotton textiles at the discharge port.

[0077] 2. Cut and disinfect waste cotton textiles

[0078] (1) Arrange the sterilized waste cotton fabrics, place them in the same direction, and send them into the TC cutting machine (ZD220, Shandong Tongchen Co., Ltd.) for cutting so that they are distributed as evenly as possible on the cutting machine conveyor belt.

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

[0080] (3) Start the machine, send the sorted fabrics to the cutting machine inlet through the conveyor belt, and collect and process the fabrics in the cutting direction (horizontal) at the outlet. Figure 1 ).

[0081] (4) Repeat the above steps 1, 2, and 3 for the fabric collected and processed once in the cutting direction, and collect and process the fabric in two cutting directions (horizontally and longitudinally) at the outlet. Finally, a small piece of cotton cloth with a longitudinal cutting length of 1 mm and a transverse cutting length of 1 mm is obtained ( Figure 2 ).

[0082] 3. Dissociate cotton cloth

[0083] (1) Soak the cut cotton cloth (10 g) in water (3000 g) at a weight ratio of water to cotton cloth = 300:1 at room temperature overnight (10-12 h);

[0084] (2) The soaked cotton cloth was dissociated using a fiber dissociator (CV-SJ-B, manufactured by Dongguan Xiwaka Precision Measuring Instrument Co., Ltd.) with a dissociation parameter of 3W and a rotation speed of 3000 rpm to obtain a cotton pulp ( Figure 3 ).

[0085] 4. Water bath treatment

[0086] The cotton pulp was heated and boiled in a water bath with a water bath temperature of 70°C and a water bath time of 1 h.

[0087] 5. Handmade paper

[0088] (1) PEO (polyethylene oxide, Sumitomo, Japan, model: PFZ blue, molecular weight: 7.5 million) was added to cotton pulp (3010 g) at a final concentration of 0.02 wt% (0.602 g). During the addition process, the solution was stirred continuously to ensure uniform mixing.

[0089] (2) PVA (polyvinyl alcohol, Shanghai Chenqi Chemical Technology Co., Ltd., model: cold-melt 2688, molecular weight: 114400-123200) with a final concentration of 0.05 wt% (1.505 g) was added to the cotton pulp (3010 g). During the addition process, the solution was continuously stirred to mix it evenly to obtain pulp.

[0090] (3) Use an A5-sized papermaking frame to make paper, apply a pressure of 675 Pa on the paper, and pressurize until there is no obvious filtrate on the paper.

[0091] (4) Place in a drying oven and dry for 6 hours, setting the drying oven temperature to 65°C.

[0092] (5) After the paper is dried, take it out from the frame to get recycled paper (such as Figure 4 ).

[0093] The recycled paper prepared in this embodiment has a unique wrinkled texture and a soft paper surface feel, and can be used in fields such as artistic packaging, and has good market prospects.

[0094] Example 2

[0095] This embodiment provides a method for preparing recycled paper. Except that in the hand-papermaking step (1), PEO with a final concentration of 0.05 wt% (1.505 g) is added to the cotton pulp (3010 g), other operations are the same as those in Example 1.

[0096] The recycled paper prepared in this embodiment is as follows Figure 5 As shown, recycled paper has a unique wrinkled texture and a soft paper surface feel.

[0097] Example 3

[0098] This embodiment provides a method for preparing recycled paper. Except that in the hand-papermaking step (1), PVA with a final concentration of 0.1 wt% (3.01 g) is added to the cotton pulp (3010 g), other operations are the same as those in Example 1.

[0099] The recycled paper prepared in this embodiment is as follows Figure 6 As shown, recycled paper has a unique wrinkled texture and a soft paper surface feel.

[0100] Example 4

[0101] This embodiment provides a method for preparing recycled paper. Except that in the cotton cloth dissociation step, green cotton cloth (waste cotton blended textile, cut into small pieces of cotton cloth with a length and width of 1 mm×1 mm as in Example 1) and black cotton cloth (waste cotton blended textile, cut into small pieces of cotton cloth with a length and width of 1 mm×1 mm as in Example 1) are uniformly 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 in Example 1.

[0102] The recycled paper prepared in this embodiment is as follows Figure 7 As shown, recycled paper has a unique wrinkled texture and soft paper surface feel, 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 that in the cotton cloth dissociation step, white cotton fibers (cut into small pieces of cotton cloth with a length and width of 1 mm×1 mm as in 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 as in the method of Example 1) are uniformly mixed in a ratio of 1:1 (5 g each) and then water is added for soaking, other operations are the same as in Example 1.

[0105] The recycled paper prepared in this embodiment is as follows Figure 8 As shown, recycled paper has a unique wrinkled texture and soft paper surface feel, 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 that in the step of dissociating the cotton cloth, pulp (long-fiber dehydrated pulp, mainly composed of pine tree fibers such as paper mulberry bark, with a length distribution of 2-3 mm, manufactured by Shandong Jinan Lexiu Zhibao Co., Ltd.) and cotton cloth (cut into small pieces of 1 mm × 1 mm in length and width as in Example 1) are uniformly mixed in a ratio of 1:1 (5 g each), and then water is added for soaking, other operations are the same as in Example 1.

[0108] In this embodiment, recycled paper can also be successfully prepared using pulp and cotton cloth. Figure 9 As shown, recycled paper has a unique wrinkled texture and a soft paper surface feel.

[0109] Performance Testing

[0110] The recycled paper and wood pulp fiber handmade paper of Example 1, Example 4, and Example 6 (made from long fiber dehydrated pulp purchased from Shandong Jinan Lexiu Zhibao Co., Ltd. and prepared according to the method of Example 1) were subjected to paper tensile strength measurement (using GB / T 1291-2018 standard, instrument: hand-cranked vertical testing machine, model: ZP-100N, manufacturer: Shenzhen Ailigu Instrument Co., Ltd.) and air permeability measurement (using GB / T 5453-1997 standard, instrument: fully automatic air permeability tester, model: YD-TQD-A, manufacturer: Guangdong Yunda Machinery Equipment Manufacturing Co., Ltd.). 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 Wood pulp fiber handmade paper 1.380 38.2

[0113] From the results in Table 1, it can be seen that compared with the wood pulp fiber handmade paper prepared with long fiber dehydrated pulp as raw material, the recycled paper prepared with waste cotton textiles, waste cotton blended textiles, and a mixture of waste cotton textiles and long fiber dehydrated pulp as raw materials (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 hand-papermaking step (2), PVA with a final concentration of 0.15 wt% (4.515 g) is added to the cotton pulp (3010 g), other operations are the same as those in Example 1.

[0116] The recycled paper prepared in this comparative example is Figure 10 As shown, the paper broke directly during the unframing process due to its loose structure. We analyzed that the possible reasons are: the PVA concentration is too high, the pulp viscosity is too high, and the fibers are severely clumped together, resulting in an excessively loose paper structure, which breaks and cannot be formed into sheets. In addition, there is too much PVA, and the excess glue causes the paper to turn yellow after drying.

[0117] Comparative Example 2

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

[0119] The recycled paper prepared in this comparative example is Figure 11As shown in the figure, the paper was damaged during the unframing process due to its loose structure. We believe that the reasons may be that the PEO concentration is too high, the fibers are overly dispersed, and the fibers cannot adhere well to each other. In addition, there is still excess unmelted PEO on the paper surface. During drying, the unmelted PEO remains on the paper surface, causing transparent pits on the paper surface, making the paper structure even looser and more fragile.

[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 be used to make recycled paper. Figure 12 We analyzed that the possible reason is that after cutting, the length and width of the cotton cloth were too long, and the cotton cloth area was too large, resulting in the fiber separator blades being unable to disintegrate part of the cotton cloth. A large number of lumps of cotton cloth were present in the cotton pulp, which made it impossible to separate the cotton cloth into single fibers during hand-made papermaking. Instead, the fibers were in lumps on the paper, resulting in loose entanglement between the fibers and a loose structure, which ultimately made it impossible to make paper.

[0123] Comparative Example 4

[0124] This comparative example provides a method for preparing recycled paper. Except that the dissociation parameter for cotton cloth is 2 revolutions, 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 the recycled paper has uneven ridges. We believe that the reason may be that the number of revolutions used when disintegrating the cotton cloth is insufficient, and some undisintegrated cotton cloth exists in the cotton pulp. During hand-made papermaking, it cannot be retained as a single fiber in the paper, resulting in uneven ridges on the paper surface.

[0126] Comparative Example 5

[0127] This comparative example provides a method for preparing recycled paper. Except for not performing the cotton cloth dissociation step, 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 pushing small pieces of cotton cloth, such as Figure 14 We analyzed that the reason is that the cotton cloth was not dissociated, which resulted in the cotton cloth not being able to present a single fiber state during papermaking. The cotton fibers in the small bundles 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 (handmade papermaking adhesive: plant rhizome extract, purchased from Anhui Shiguang Zaowu Culture Technology Co., Ltd.) with a final concentration of 0.05 wt% (1.505 g) is added to the cotton pulp (3010 g), the other operations are the same as those in Example 1.

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

[0132] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0133] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A method for preparing recycled paper, characterized in that: It consists of the following steps: Step 1: chopping the waste textiles after anhydrous 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 10 h-12 h; Step 3: using a fiber disintegrator to dissociate into a single fiber state to obtain cotton pulp; subjecting the cotton pulp to a water bath treatment; the dissociation parameters are 30,000 to 50,000 rpm, a rotation speed of 1,000 to 3,600 rpm; the temperature of the water bath is 70° C. to 85° C., and the water bath time is 1 h to 1.5 h; Step 4: Add polyethylene oxide to a final concentration of 0.02 wt% to 0.05 wt% to the cotton pulp and stir; then add polyvinyl alcohol to a final concentration of 0.05 wt% to 0.1 wt% and stir; Step 5: Papermaking and pressurization; Step 6: Drying to obtain recycled paper.

2. The preparation method according to claim 1, characterized in that In step 1, the anhydrous disinfection treatment comprises the steps of: subjecting the waste textiles to a 20,000 μJ / cm 2 ~25000 μJ / cm 2 Irradiate under UV-C light for 30 min~60 min; And / or, cutting the waste textiles into cotton cloth with a length and 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, with the longitudinal cutting length being 1 mm to 3 mm and the transverse cutting length being 1 mm to 3 mm.

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.

5. The preparation method according to claim 4, characterized in that The weight ratio of the cotton cloth to water is 1:310-330.

6. The preparation method according to claim 1, characterized in that The dissociation parameters are 30,000 to 40,000 rpm and a rotation speed of 3,000 to 3,600 rpm.

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

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

9. The preparation method according to claim 1, characterized in that Step six includes: placing in a dryer and drying at 40°C to 75°C.

10. The preparation method according to claim 9, characterized in that The drying time is 4 h to 8 h.

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

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