High-strength and high-toughness paper for paper yarn and preparation method thereof

Abstract

The present invention provides a high-strength and high-toughness paper for paper yarn and a preparation method thereof, belonging to the technical field of textile and papermaking. The paper for paper yarn provided by the present invention is prepared by bleached softwood kraft pulp, cationic modified microfibrillated cellulose, cationic reinforcing additives and functional additives through round screen molding, micro-wrinkling and sizing; the glue during sizing is a flexible polymer glue. The present invention utilizes cationic modified microfibrillated cellulose to improve the mechanical strength performance of paper for paper yarn, and through a micro-wrinkling process and impregnation sizing flexible polymer, the paper for paper yarn has both high strength and high toughness.

Description

Technical Field

[0001] The invention belongs to the technical field of textile and papermaking, and in particular relates to high-strength and high-toughness paper for paper yarn and a preparation method thereof. Background Art

[0002] Paper yarn paper is made of plant fiber as the main raw material, and is produced into paper through sheeting, pressing and drying. In recent years, scientific researchers in the domestic pulp and paper industry have actively carried out some research work on paper yarn paper, focusing mainly on improving the strength of yarn paper by adding different reinforcing fibers or reinforcing additives to improve the strength of paper, such as adding non-plant fibers, namely bacterial fibers or polyvinyl alcohol fibers to greatly improve the mechanical strength of the base paper. However, in the prior art, paper yarn paper has a low elongation and poor toughness, and paper yarn paper often breaks due to poor toughness (low elongation) during the actual yarn making and weaving process, affecting practical applications. Therefore, there is an urgent need for a paper yarn paper that has both high strength and high toughness (elongation). Summary of the invention

[0003] The purpose of the present invention is to provide a high-strength and high-toughness paper yarn that can be used in the textile field, and to provide a method for preparing paper yarn that is suitable for production by a modern papermaking machine. The paper yarn provided by the present invention has both high strength and high toughness.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] The invention provides a high-strength and high-toughness paper for paper yarn, which is prepared by bleached softwood kraft pulp, cationic modified microfibrillated cellulose, cationic reinforcing aids and functional aids through round screen forming, micro-wrinkling and sizing; the cationic reinforcing aids include wet strength agents and dry strength agents, the functional aids are softeners; the glue during sizing is a flexible polymer glue; the basis weight of the paper for paper yarn is 16-22 g / m 2 , the aspect ratio is 5 to 8.

[0006] The present invention also provides a method for preparing the high-strength and high-toughness paper yarn paper described in the above technical solution, comprising the following steps:

[0007] (1) mixing bleached softwood kraft pulp with water, cationic modified microfibrillated cellulose, a cationic reinforcing agent and a functional additive to obtain a pulp fiber suspension;

[0008] (2) subjecting the pulp fiber suspension obtained in step (1) to cylinder-wire forming and pressing in sequence to obtain a paper web in which the pulp fibers are arranged longitudinally;

[0009] (3) The paper web with pulp fibers arranged longitudinally obtained in step (2) is subjected to first drying, micro-wrinkling, sizing, second drying, calendering and winding in sequence to obtain high-strength and high-toughness paper for paper yarn; the glue used in the sizing is a flexible polymer glue.

[0010] Preferably, in step (1), the beating degree of the bleached softwood kraft pulp is 30-55°SR, and the wet weight of the fibers in the bleached softwood kraft pulp is 9-13 g.

[0011] Preferably, the cation in the cation-modified microfibrillated cellulose in step (1) comprises a quaternary ammonium cation, a phosphonium cation or a sulfonium cation; the degree of substitution of the cation-modified microfibrillated cellulose is 5 to 9 mol%, the diameter of the cation-modified microfibrillated cellulose is 200 to 500 nm, and the aspect ratio of the cation-modified microfibrillated cellulose is 50 to 300.

[0012] Preferably, in step (1), the mass ratio of the cationic modified microfibrillated cellulose to the fibers in the bleached softwood kraft pulp is (1-5): (95-99).

[0013] Preferably, based on the mass of solids in the wet strength agent, the mass ratio of the wet strength agent to the fibers in the bleached softwood kraft pulp in step (1) is (1-2):100.

[0014] Preferably, based on the solid mass of the dry strength agent, the mass ratio of the dry strength agent to the fiber in the bleached softwood kraft pulp in step (1) is (0.2-1):100.

[0015] Preferably, the flexible polymer glue in step (3) comprises one or more of aqueous polyurethane, polyvinyl alcohol solution, acrylate emulsion, ethylene-acrylic acid copolymer emulsion and ethylene-vinyl acetate copolymer emulsion.

[0016] Preferably, the amount of glue applied in step (3) is 0.5 to 3.0 g / m 2 .

[0017] Preferably, the wrinkling rate of the micro-wrinkling in step (3) is 5 to 15%.

[0018] The invention provides a high-strength and high-toughness paper for paper yarn, which is prepared by bleached softwood kraft pulp, cationic modified microfibrillated cellulose, cationic reinforcing aids and functional aids through round screen forming, micro-wrinkling and sizing; the cationic reinforcing aids include wet strength agents and dry strength agents, the functional aids are softeners; the glue during sizing is a flexible polymer glue; the basis weight of the paper for paper yarn is 16-22 g / m 2, the aspect ratio is 5 to 8. The cationic modified microfibrillated cellulose in the present invention is used as a reinforcing agent for paper yarn. The surface of bleached coniferous kraft pulp fiber is negatively charged, and the surface of the cationic modified microfibrillated cellulose contains a certain amount of cations and thus carries a positive charge. The electrostatic adsorption force can increase the binding force between it and the bleached coniferous kraft pulp fiber; in addition, the cationic modified microfibrillated cellulose can increase the bonding area between pulp fibers through physical interweaving and entanglement. Through the above two forms of action, the addition of cationic modified microfibrillated cellulose significantly improves the mechanical strength performance of paper yarn; through the micro-wrinkling process and the impregnation sizing flexible polymer, the two work synergistically to improve the toughness of paper yarn, thereby making the paper yarn paper have both high strength and high toughness. The results of the embodiment show that the longitudinal tensile strength of the paper yarn provided by the present invention is above 31.7N, and the longitudinal elongation is above 3.8%. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic flow chart of the method for preparing paper for paper yarn in Example 1 of the present invention. DETAILED DESCRIPTION

[0020] The invention provides a high-strength and high-toughness paper for paper yarn, which is prepared by bleached softwood kraft pulp, cationic modified microfibrillated cellulose, cationic reinforcing aids and functional aids through round screen forming, micro-wrinkling and sizing; the cationic reinforcing aids include wet strength agents and dry strength agents, the functional aids are softeners; the glue during sizing is a flexible polymer glue; the basis weight of the paper for paper yarn is 16-22 g / m 2 , the aspect ratio is 5 to 8.

[0021] The present invention utilizes cationic modified microfibrillated cellulose to improve the mechanical strength of paper for paper yarn, and through a micro-wrinkling process and impregnation sizing flexible polymer, the paper for paper yarn has both high strength and high toughness. The paper for paper yarn provided by the present invention has both high strength and high toughness, can meet the application of paper for paper yarn in the field of textile and yarn making, and is adapted to the existing papermaking process and can meet industrial production.

[0022] The present invention also provides a method for preparing the high-strength and high-toughness paper yarn paper described in the above technical solution, comprising the following steps:

[0023] (1) mixing bleached softwood kraft pulp with water, cationic modified microfibrillated cellulose, a cationic reinforcing agent and a functional additive to obtain a pulp fiber suspension;

[0024] (2) subjecting the pulp fiber suspension obtained in step (1) to cylinder-wire forming and pressing in sequence to obtain a paper web in which the pulp fibers are arranged longitudinally;

[0025] (3) The paper web with pulp fibers arranged longitudinally obtained in step (2) is subjected to first drying, micro-wrinkling, sizing, second drying, calendering and winding in sequence to obtain high-strength and high-toughness paper for paper yarn; the glue used in the sizing is a flexible polymer glue.

[0026] Unless otherwise specified, the present invention has no particular limitation on the sources of the raw materials, and commercially available products known to those skilled in the art may be used.

[0027] The invention mixes bleached conifer kraft pulp with water, cationic modified microfibrillated cellulose, cationic reinforcing auxiliary agent and functional auxiliary agent to obtain pulp fiber suspension.

[0028] In the present invention, the beating degree of the bleached softwood kraft pulp is preferably 30-55°SR, more preferably 30°SR, 35°SR, 40°SR, 45°SR or 50°SR; the wet weight of the fiber in the bleached softwood kraft pulp is preferably 9-13g, more preferably 9-12g, and further preferably 9-11g. In the present invention, the beating degree of the bleached softwood kraft pulp and the wet weight of the fiber are selected within the above ranges, which can further improve the strength and toughness of paper for paper yarn.

[0029] When the beating degree and wet weight of the bleached softwood kraft pulp are out of the above ranges, the present invention preferably performs beating on the bleached softwood kraft pulp.

[0030] In the present invention, the bleached softwood kraft pulp is preferably beaten by a refiner, and more preferably three single-disc refiners connected in series are used to perform long-fiber sticky beating.

[0031] In the present invention, the pulping concentration is preferably 3-6%; the pulping machine throughput is preferably 30-50m 3 / h. The present invention has no special limitation on other parameters during the beating. The beating technical scheme well known to those skilled in the art can be used to ensure that the beating degree of the bleached softwood kraft pulp after beating is within the range of 30-55°SR and the fiber wet weight is within the range of 9-13g.

[0032] The present invention has no special limitation on the source of the bleached softwood kraft pulp, and commercial products known to those skilled in the art can be used. In the embodiment of the present invention, the bleached softwood kraft pulp is preferably the "Silver Star" brand of the Chilean Arauco Group, the "GP" brand of Georgia-Pacific, or the "Moon" brand of the Canadian Mercer Celgar pulp mill.

[0033] In the present invention, the cationically modified microfibrillated cellulose is preferably quaternary ammonium salt-modified microfibrillated cellulose, pyridinium salt-modified microfibrillated cellulose, phosphonium salt-modified microfibrillated cellulose or sulfonium salt-modified microfibrillated cellulose, and more preferably quaternary ammonium salt-modified microfibrillated cellulose. In the present invention, the cationically modified microfibrillated cellulose is used as a reinforcing agent for paper yarns. The surface of bleached coniferous kraft pulp fibers is negatively charged, and the surface of the cationically modified microfibrillated cellulose contains a certain amount of cations and thus carries a positive charge. The electrostatic adsorption force can increase the binding force between the cationically modified microfibrillated cellulose and the bleached coniferous kraft pulp fibers; in addition, the cationically modified microfibrillated cellulose can increase the bonding area between pulp fibers through physical interweaving and entanglement. Through the above two forms of action, the addition of cationically modified microfibrillated cellulose significantly improves the mechanical strength performance of paper yarns.

[0034] In the present invention, the degree of substitution of the cationically modified microfibrillated cellulose is preferably 5-9 mol%, more preferably 6-8 mol%. In the present invention, when the cationically modified microfibrillated cellulose is quaternary ammonium salt-modified microfibrillated cellulose, the degree of substitution of the quaternary ammonium salt group is preferably characterized by the content of amino groups.

[0035] In the present invention, the diameter of the cationically modified microfibrillated cellulose is preferably 200 to 500 nm; the aspect ratio of the cationically modified microfibrillated cellulose is preferably 50 to 300. The present invention selects the degree of substitution, diameter and aspect ratio of the cationically modified microfibrillated cellulose within the above ranges, which can further increase the binding force with the bleached softwood kraft pulp fiber through electrostatic adsorption, and at the same time has a higher specific surface area and a higher aspect ratio, which can further increase the bonding area between pulp fibers through entanglement, and further improve the strength of paper yarn paper.

[0036] The present invention has no special limitation on the source of the cationic modified microfibrillated cellulose, and a commercial product or a product prepared by a conventional preparation method known to those skilled in the art can be used. In an embodiment of the present invention, the preparation method of the quaternary ammonium salt modified microfibrillated cellulose is as follows: APMP pulp (poplar APMP pulp, Shandong Dezhou Zhongmao Shengyuan Paper Co., Ltd.) is ground and beaten to 37°SR by PFI, 7.53g of pulp (equivalent to 1g of absolute dry pulp) is weighed and put into a beaker, and sodium hydroxide solution (the mass of sodium hydroxide is 1% of the mass of absolute dry pulp) and 3-chloro-2-hydroxypropyltrimethylammonium chloride are added successively, and deionized water is added to adjust the pulp concentration to 8%, and stirred evenly. Then, it is placed in a 50°C water bath for reaction for 60 minutes. After the reaction is completed, the pulp is transferred to a Buchner funnel for filtration and washing, and the filtrate is tested with a silver nitrate solution until no precipitation is produced, and the water content is balanced in a polyethylene bag to obtain quaternary ammonium salt modified microfibrillated cellulose.

[0037] In the present invention, the mass ratio of the cationically modified microfibrillated cellulose to the fibers in the bleached softwood kraft pulp is preferably (1-5): (95-99), more preferably (2-5): (95-98), and further preferably (3-5): (95-97). In the present invention, the mass of the fibers in the bleached softwood kraft pulp is preferably measured by the absolute dry mass of the fibers. The present invention selects the mass ratio of the cationically modified microfibrillated cellulose to the fibers in the bleached softwood kraft pulp within the above range, which can further improve the strength and toughness of paper for paper yarn.

[0038] In the present invention, the cationic strengthening aid includes a wet strength agent and a dry strength agent.

[0039] In the present invention, the wet strength agent is preferably polyamide epichlorohydrin (PAE). In the present invention, the average molecular weight of the polyamide epichlorohydrin is preferably ≤10W. In the present invention, the wet strength agent can be adsorbed onto the negatively charged fiber surface, form hydrogen bonds with the hydroxyl groups on the fiber surface, improve the bonding force between fibers, and thus improve the strength of paper.

[0040] In the present invention, the mass ratio of the wet strength agent to the fiber in the bleached softwood kraft pulp is preferably (1-2):100, more preferably (1.2-1.8):100, based on the solid mass in the wet strength agent. In the present invention, the mass of the fiber in the bleached softwood kraft pulp is preferably based on the absolute dry mass of the fiber. In the present invention, the mass ratio of the wet strength agent to the fiber in the bleached softwood kraft pulp is selected within the above range, which can further improve the strength of the paper.

[0041] In the present invention, the solid content of the wet strength agent is preferably 1-2%. In the present invention, the solid content of the wet strength agent is selected within the above range, which can make its viscosity lower and more convenient to add.

[0042] When the solid content of the wet strength agent is not within the above range, the present invention preferably dilutes the wet strength agent by mixing it with water. The present invention has no particular limitation on the amount of water used during the dilution, as long as the solid content of the wet strength agent after dilution is within the above range.

[0043] In the present invention, the dry strength agent is preferably cationic polyacrylamide (CPAM). In the present invention, the average molecular weight of the cationic polyacrylamide is preferably 10 to 100 W. In the present invention, the dry strength agent can be adsorbed onto the negatively charged fiber surface, forming hydrogen bonds with the hydroxyl groups on the fiber surface, thereby increasing the bonding force between the fibers and thus increasing the strength of the paper.

[0044] In the present invention, the mass ratio of the dry strength agent to the fiber in the bleached softwood kraft pulp is preferably (0.2-1):100, more preferably (0.3-0.8):100, based on the solid mass in the dry strength agent. In the present invention, the mass of the fiber in the bleached softwood kraft pulp is preferably based on the absolute dry mass of the fiber. In the present invention, the mass ratio of the dry strength agent to the fiber in the bleached softwood kraft pulp is selected within the above range, which can further improve the strength of the paper.

[0045] In the present invention, the solid content of the dry strength agent is preferably 1-2%. In the present invention, the solid content of the dry strength agent is selected within the above range, which can make its viscosity lower and more convenient to add.

[0046] When the solid content of the dry strength agent is not within the above range, the present invention preferably dilutes the dry strength agent by mixing it with water. The present invention has no particular limitation on the amount of water used during the dilution, as long as the solid content of the dry strength agent after dilution is within the above range.

[0047] In the present invention, the functional auxiliary agent is a softener.

[0048] In the present invention, the softener is preferably a natural vegetable oil-based softener. The present invention has no particular limitation on the source of the softener, and any softener known to those skilled in the art can be used. In an embodiment of the present invention, the natural vegetable oil-based softener is preferably TS22 produced by Guanhong Chemical (Yangzhou) Co., Ltd.

[0049] In the present invention, the mass ratio of the softener to the fiber in the bleached softwood kraft pulp is preferably (0.01-0.3):100, more preferably (0.05-0.25):100, based on the solid mass in the softener. In the present invention, the mass of the fiber in the bleached softwood kraft pulp is preferably based on the absolute dry mass of the fiber. In the present invention, the mass ratio of the softener to the fiber in the bleached softwood kraft pulp is selected within the above range, which can further improve the softness of the paper.

[0050] In the present invention, the solid content of the softener is preferably 0.5-1.5%. The present invention selects the solid content of the softener within the above range, which can make its viscosity lower and more convenient to add.

[0051] When the solid content of the softener is not within the above range, the present invention preferably dilutes the softener by mixing it with water at 55-65° C. The present invention has no particular limitation on the amount of water used during the dilution, as long as the solid content of the softener after dilution is within the above range.

[0052] In the present invention, the ratio of the mass of the fiber in the bleached softwood kraft pulp to the total mass of the bleached softwood kraft pulp and water is preferably (0.05-0.5): 100, and more preferably (0.1-0.5): 100. In the present invention, the ratio of the mass of the fiber in the bleached softwood kraft pulp to the total mass of the bleached softwood kraft pulp and water is selected within the above range, which is more conducive to the mixing of the raw materials and the smooth progress of the subsequent processes.

[0053] The present invention has no special limitation on the amount of water, as long as the ratio of the mass of the fiber in the bleached softwood kraft pulp to the total mass of the bleached softwood kraft pulp and water is within the above range.

[0054] In the present invention, the mixing of the bleached softwood kraft pulp with water, cationic modified microfibrillated cellulose, cationic reinforcing agent and functional additive is preferably as follows: the bleached softwood kraft pulp is mixed with water and stirred for 5 to 20 minutes, the cationic modified microfibrillated cellulose is added and stirred for 5 to 20 minutes, the wet strength agent is added and stirred for 5 to 20 minutes, the dry strength agent is added and stirred for 5 to 20 minutes, and the softener is added and stirred for 5 to 20 minutes. The present invention has no particular limitation on the stirring rate, and the stirring rate well known to those skilled in the art can be used to uniformly mix the raw materials. In the present invention, the mixing is preferably carried out in the pre-papermaking tank of the paper machine.

[0055] After obtaining the pulp fiber suspension, the present invention sequentially performs cylinder-net forming and pressing on the pulp fiber suspension to obtain a paper web in which the pulp fibers are arranged longitudinally.

[0056] The present invention preferably conveys the pulp fiber suspension to the mesh cage of the rotary paper machine, controls the vehicle speed, adjusts the movable arc plate of the rotary paper machine, shapes the pulp fibers to have a longitudinal arrangement, and then presses to obtain a paper web with longitudinally arranged pulp fibers.

[0057] In the present invention, the vehicle speed is preferably 50-80 m / min. In the present invention, the distance between the arc plate and the cylinder screen is preferably 5-15 mm; the opening angle of the arc plate is preferably 8-25°. The present invention selects the parameters of the vehicle speed and the arc plate within the above range, so that the pulp fibers can be better arranged longitudinally, thereby improving the aspect ratio of the paper, and further improving the strength and toughness of the paper.

[0058] The present invention has no special limitation on the pressing operation, and a pressing technical solution well known to those skilled in the art can be used to ensure that the basis weight of the paper web is within a limited range.

[0059] In the present invention, the basis weight of the paper web in which the pulp fibers are arranged longitudinally is preferably 15 to 21 g / m 2In the present invention, the basis weight of the paper web in which the pulp fibers are arranged longitudinally is selected within the above range, which is more conducive to the subsequent sizing process.

[0060] After obtaining the paper web with pulp fibers arranged longitudinally, the present invention sequentially performs first drying, slight wrinkling, sizing, second drying, calendering and winding on the paper web with pulp fibers arranged longitudinally to obtain paper for paper yarn.

[0061] In the present invention, the glue used in the sizing is a flexible polymer glue; the flexible polymer glue preferably includes one or more of aqueous polyurethane, polyvinyl alcohol solution, acrylate emulsion, ethylene-acrylic acid copolymer emulsion and ethylene-vinyl acetate copolymer emulsion. In the present invention, the solid content of the glue is preferably 20-45%. In the present invention, the average molecular weight of the polyurethane in the aqueous polyurethane is preferably 2W; the average molecular weight of the polyvinyl alcohol in the polyvinyl alcohol solution is preferably 1.5W; the acrylate in the acrylate emulsion is preferably butyl methacrylate; the average molecular weight of the ethylene-acrylic acid copolymer in the ethylene-acrylic acid copolymer emulsion is preferably 2.5W; the average molecular weight of the ethylene-vinyl acetate copolymer in the ethylene-vinyl acetate copolymer emulsion is preferably 2.5W. In the present invention, the glue fills the pores of the three-dimensional network structure of the paper and improves the toughness of the paper. The present invention selects the average molecular weight of the polymer in the glue within the above range, which can make the glue have better flexibility and further improve the toughness of the paper.

[0062] In the present invention, the amount of glue applied during the gluing is preferably 0.5 to 3.0 g / m 2 , more preferably 1.0 to 3.0 g / m 2 The present invention selects the glue amount within the above range, which can further improve the toughness of the paper.

[0063] In the present invention, the temperature of the first drying is preferably 90-105°C; the moisture content of the paper web after the first drying is preferably 15-25%. The present invention has no special limitation on the time of the first drying, as long as the moisture content of the paper web after drying is within the above range.

[0064] In the present invention, the paper web is preferably micro-creped using a creping blade when passing through the creping zone of the drying section. In the present invention, the moisture content during micro-creping is preferably 15-25%.

[0065] In the present invention, the material of the corrugating scraper is preferably ceramic; the scraper holder angle of the corrugating scraper is preferably 15-25°; the corrugating angle of the corrugating scraper is preferably 70-90°; the scraper pressure of the corrugating scraper is preferably 10-25N / cm 2 .

[0066] In the present invention, the wrinkling rate of the micro-wrinkling is preferably 5 to 15%. The present invention selects the wrinkling rate within the above range to further improve the toughness of the paper.

[0067] In the present invention, the temperature of the second drying is preferably 80 to 110° C.; the time of the second drying is preferably 10 to 40 seconds.

[0068] In the present invention, the calendering line pressure is preferably 10 to 30 N / mm; the calendering temperature is preferably 30 to 60° C.; and the paper thickness after calendering is preferably 25 to 35 μm.

[0069] In the present invention, the winding tension is preferably 30 to 80 N; the winding speed is preferably 20 to 70 m / min.

[0070] The present invention adds cationic modified microfibrillated cellulose to improve the strength of paper, but cellulose is a linear polysaccharide, which is composed of glucose structural units connected by β-1,4-glycosidic bonds and arranged into neat bundle structures. Due to the presence of intramolecular and intermolecular hydrogen bonds, the cellulose fibers have a certain rigidity, which makes the elongation of the paper relatively low, at about 1-2%. The present invention uses a micro-wrinkling process, then impregnates the glue and controls the type of the glue, so that the paper yarn has both high strength and high toughness. At the same time, the preparation method is green and environmentally friendly and can be industrially produced.

[0071] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0072] The preparation method of quaternary ammonium salt modified microfibrillated cellulose in each embodiment is as follows: APMP pulp (poplar APMP pulp, Shandong Dezhou Zhongmao Shengyuan Paper Co., Ltd.) is beaten to 37°SR by PFI grinding to obtain pulp, 7.53g of pulp (equivalent to 1g of absolute dry pulp) is weighed and put into a beaker, sodium hydroxide solution (the mass of sodium hydroxide is 1% of the mass of absolute dry pulp) and 3-chloro-2-hydroxypropyltrimethylammonium chloride are added successively, deionized water is added to adjust the pulp concentration to 8%, stirred evenly, and then placed in a 50°C water bath to react for 60 minutes. After the reaction is completed, the pulp is transferred to a Buchner funnel for filtration and washing, and the filtrate is detected with a silver nitrate solution, washed until no precipitation is produced, and placed in a polyethylene bag to balance the moisture to obtain quaternary ammonium salt modified microfibrillated cellulose.

[0073] Example 1

[0074] The schematic diagram of the process for preparing paper yarn paper provided in Example 1 is as follows Figure 1 As shown, pulp fiber (bleached softwood kraft pulp) is refined (i.e., beaten), cationic modified microfibrillated cellulose, cationic reinforcing agents (dry strength agent and wet strength agent), and functional additives (softener) are added to prepare the pulp, and the paper is subjected to wire forming, pressing, first drying, micro-wrinkling, impregnation sizing, second drying, calendering, and winding to obtain high-strength and high-toughness paper yarn paper; the specific preparation method is:

[0075] (1) Commercial bleached softwood kraft pulp (Silver Star brand of Chile's Arauco Group) was subjected to long fiber sticky pulping using three single-disc refiners in series, with a pulping concentration of 4.0%, a power of 60 kW, and a refiner throughput of 33 m 3 / h, the final beating degree of the bleached softwood kraft pulp is 35°SR, and the wet weight of the fiber is 10.8g;

[0076] (2) The bleached softwood kraft pulp after beating is pumped to the paper machine for mixing, water is added to adjust the pulp fiber mass concentration to 0.1% (the ratio of the mass of the fiber in the bleached softwood kraft pulp to the total mass of the bleached softwood kraft pulp and water is 0.1:100), and quaternary ammonium salt-modified microfibrillated cellulose with a substitution degree (based on amino groups) of 6 mol% (the mass ratio of the quaternary ammonium salt-modified microfibrillated cellulose to the fiber in the bleached softwood kraft pulp (based on the absolute dry mass of the fiber) is 3:97), PAE wet strength agent (average molecular weight of 8W, solid content of 1%, based on the solid mass in the wet strength agent, the mass ratio of the wet strength agent to the fiber in the bleached softwood kraft pulp is 1.2:100), bleached The mass of the fiber in the softwood kraft pulp is calculated based on the absolute dry mass of the fiber), CPAM dry strength agent (average molecular weight 40W, solid content 1%, calculated based on the solid mass in the dry strength agent, the mass ratio of the dry strength agent to the fiber in the bleached softwood kraft pulp is 0.3:100, and the mass of the fiber in the bleached softwood kraft pulp is calculated based on the absolute dry mass of the fiber), natural vegetable oil-based softener (TS22 produced by Guanhong Chemical (Yangzhou) Co., Ltd., solid content 1%, calculated based on the solid mass in the softener, the mass ratio of the softener to the fiber in the bleached softwood kraft pulp is 0.15:100, and the mass of the fiber in the bleached softwood kraft pulp is calculated based on the absolute dry mass of the fiber), and stirred for 15 minutes respectively to obtain a pulp fiber suspension;

[0077] (3) The pulp fiber suspension was transported to the cylinder of the cylinder paper machine, the speed was controlled at 65 m / min, the movable arc plate of the cylinder paper machine was adjusted, the distance between the arc plate and the cylinder was 10 mm, and the opening angle of the arc plate was 18°, so that the pulp fibers were arranged longitudinally, and the wet paper web was obtained through the wire forming and pressing process, and the basis weight of the paper web was controlled at 17.0 ± 0.5 g / m 2 ;

[0078] (4) After the paper web passes through the first drying section (drying temperature 95°C, moisture content 20%), the wrinkling area is adjusted to the wrinkling angle of the wrinkling scraper 83° (the material of the wrinkling scraper is ceramic; the angle of the scraper holder of the wrinkling scraper is 19°; the scraper pressure of the wrinkling scraper is 18N / cm 2 ) The paper surface is slightly wrinkled, and the wrinkling rate is 8%;

[0079] (5) When the paper web passes through the sizing section, the upper and lower coating rollers are used to immerse and sizing water-based polyurethane (solid content is 30%, the average molecular weight of polyurethane is 2W), and the amount of glue applied is controlled to 1.0 g / m 2 ;

[0080] (6) Finally, after the second drying (105°C, 25s), calendering (calendering line pressure is 15N / mm; calendering temperature is 45°C; paper thickness after calendering is 30μm) and winding (winding tension is 50N; winding speed is 65m / min) stages, high-strength and high-flexibility paper yarn paper is obtained.

[0081] Example 2

[0082] (1) Commercial bleached softwood kraft pulp (Silver Star brand of Chile's Arauco Group) was subjected to long fiber sticky pulping using three single-disc refiners in series, with a pulping concentration of 4.0%, a power of 60 kW, and a refiner throughput of 33 m 3 / h, the final beating degree of the bleached softwood kraft pulp is 45°SR, and the wet weight of the fiber is 9.7g;

[0083] (2) The bleached softwood kraft pulp after beating is pumped to the paper machine for mixing, water is added to adjust the pulp fiber mass concentration to 0.1% (the ratio of the mass of the fiber in the bleached softwood kraft pulp to the total mass of the bleached softwood kraft pulp and water is 0.1:100), and quaternary ammonium salt-modified microfibrillated cellulose with a substitution degree (based on amino groups) of 9 mol% (the mass ratio of the quaternary ammonium salt-modified microfibrillated cellulose to the fiber in the bleached softwood kraft pulp (based on the absolute dry mass of the fiber) is 1.5:98.5) and PAE wet strength agent (average molecular weight of 8W, solid content of 1%, based on the solid mass in the wet strength agent, the mass ratio of the wet strength agent to the fiber in the bleached softwood kraft pulp is 1.5:100) are added successively. The mass of the fiber in the bleached coniferous kraft pulp is calculated based on the absolute dry mass of the fiber), CPAM dry strength agent (average molecular weight 40W, solid content 1%, calculated based on the solid mass in the dry strength agent, the mass ratio of the dry strength agent to the fiber in the bleached coniferous kraft pulp is 0.5:100, and the mass of the fiber in the bleached coniferous kraft pulp is calculated based on the absolute dry mass of the fiber), natural vegetable oil-based softener (TS22 produced by Guanhong Chemical (Yangzhou) Co., Ltd., solid content 1%, calculated based on the solid mass in the softener, the mass ratio of the softener to the fiber in the bleached coniferous kraft pulp is 0.15:100, and the mass of the fiber in the bleached coniferous kraft pulp is calculated based on the absolute dry mass of the fiber), and stirred for 15 minutes respectively to obtain a pulp fiber suspension;

[0084] (3) The pulp fiber suspension was transported to the cylinder of the cylinder paper machine. The speed was controlled at 65 m / min. The movable arc plate of the cylinder paper machine was adjusted. The distance between the arc plate and the cylinder was 12 mm. The opening angle of the arc plate was 20°. The pulp fibers were arranged longitudinally. The wet paper web was obtained through the wire forming and pressing process. The basis weight of the paper web was controlled at 17.0 ± 0.5 g / m 2 ;

[0085] (4) When the paper web passes through the wrinkling zone of the first drying section (drying temperature 95°C, moisture content 20%), adjust the wrinkling angle of the wrinkling scraper to 85° (the material of the wrinkling scraper is ceramic; the angle of the scraper holder of the wrinkling scraper is 21°; the scraper pressure of the wrinkling scraper is 18N / cm 2 ) The paper surface is slightly wrinkled, and the wrinkling rate is 9%;

[0086] (5) The paper web passes through the sizing section, where the upper and lower coating rollers carry out immersion sizing of ethylene-vinyl acetate copolymer emulsion (solid content of 20%, average molecular weight of ethylene-vinyl acetate copolymer of 2.5W), and the amount of sizing is controlled to be 1.0 g / m 2 ;

[0087] (6) Finally, after the second drying (105°C, 25s), calendering (calendering line pressure is 15N / mm; calendering temperature is 45°C; paper thickness after calendering is 30μm) and winding (winding tension is 50N; winding speed is 65m / min) stages, high-strength and high-flexibility paper yarn paper is obtained.

[0088] Example 3

[0089] (1) Commercial bleached softwood kraft pulp ("GP" brand from Georgia-Pacific) was subjected to long fiber sticky pulping using three single-disc refiners in series, with a pulping concentration of 4.0%, a power of 60 kW, and a refiner throughput of 33 m 3 / h, the final beating degree of the bleached softwood kraft pulp is 35°SR, and the wet weight of the fiber is 10.8g;

[0090] (2) The bleached softwood kraft pulp after beating is pumped to the paper machine for mixing, water is added to adjust the pulp fiber mass concentration to 0.1% (the ratio of the mass of the fiber in the bleached softwood kraft pulp to the total mass of the bleached softwood kraft pulp and water is 0.1:100), and quaternary ammonium salt-modified microfibrillated cellulose with a substitution degree (based on amino groups) of 5 mol% (the mass ratio of the quaternary ammonium salt-modified microfibrillated cellulose to the fiber in the bleached softwood kraft pulp (based on the absolute dry mass of the fiber) is 5:95), PAE wet strength agent (average molecular weight of 8W, solid content of 1%, based on the solid mass in the wet strength agent, the mass ratio of the wet strength agent to the fiber in the bleached softwood kraft pulp is 1.5:100), bleached The mass of the fiber in the softwood kraft pulp is calculated based on the absolute dry mass of the fiber), CPAM dry strength agent (average molecular weight 40W, solid content 1%, calculated based on the solid mass in the dry strength agent, the mass ratio of the dry strength agent to the fiber in the bleached softwood kraft pulp is 0.5:100, and the mass of the fiber in the bleached softwood kraft pulp is calculated based on the absolute dry mass of the fiber), natural vegetable oil-based softener (TS22 produced by Guanhong Chemical (Yangzhou) Co., Ltd., solid content 1%, calculated based on the solid mass in the softener, the mass ratio of the softener to the fiber in the bleached softwood kraft pulp is 0.15:100, and the mass of the fiber in the bleached softwood kraft pulp is calculated based on the absolute dry mass of the fiber), and stirred for 15 minutes respectively to obtain a pulp fiber suspension;

[0091] (3) The pulp fiber suspension was transported to the cylinder of the cylinder paper machine, the speed was controlled at 65 m / min, the movable arc plate of the cylinder paper machine was adjusted, the distance between the arc plate and the cylinder was 12 mm, and the opening angle of the arc plate was 18°, so that the pulp fibers were arranged longitudinally, and the wet paper web was obtained through the wire forming and pressing process, and the basis weight of the paper web was controlled at 17.0 ± 0.5 g / m 2 ;

[0092] (4) When the paper web passes through the wrinkling zone of the first drying section (drying temperature 95°C, moisture content 20%), adjust the wrinkling angle of the wrinkling scraper to 83° (the material of the wrinkling scraper is ceramic; the scraper holder angle of the wrinkling scraper is 20°; the scraper pressure of the wrinkling scraper is 18N / cm 2 ) The paper surface is slightly wrinkled, and the wrinkling rate is 10%;

[0093] (5) The paper web passes through the sizing section, where the upper and lower coating rollers apply water-based polyurethane (solid content of 30%, average molecular weight of polyurethane of 2W) to the paper web. The amount of sizing is controlled to be 2.0 g / m 2 ;

[0094] (6) Finally, after the second drying (105°C, 25s), calendering (calendering line pressure is 15N / mm; calendering temperature is 45°C; paper thickness after calendering is 30μm) and winding (winding tension is 50N; winding speed is 65m / min) stages, high-strength and high-flexibility paper yarn paper is obtained.

[0095] Example 4

[0096] (1) Commercial bleached softwood kraft pulp ("GP" brand from Georgia-Pacific) was subjected to long fiber sticky pulping using three single-disc refiners in series, with a pulping concentration of 4.0%, a power of 60 kW, and a refiner throughput of 33 m 3 / h, the final beating degree of bleached softwood kraft pulp is 55°SR, and the wet weight of the fiber is 9.1g;

[0097] (2) The bleached softwood kraft pulp after beating is pumped to the paper machine for mixing, water is added to adjust the pulp fiber mass concentration to 0.1% (the ratio of the mass of the fiber in the bleached softwood kraft pulp to the total mass of the bleached softwood kraft pulp and water is 0.1:100), and quaternary ammonium salt-modified microfibrillated cellulose with a substitution degree (based on amino groups) of 6 mol% (the mass ratio of the quaternary ammonium salt-modified microfibrillated cellulose to the fiber in the bleached softwood kraft pulp (based on the absolute dry mass of the fiber) is 3:97), PAE wet strength agent (average molecular weight of 8W, solid content of 1%, based on the solid mass in the wet strength agent, the mass ratio of the wet strength agent to the fiber in the bleached softwood kraft pulp is 1.2:100), bleached The mass of the fiber in the softwood kraft pulp is calculated based on the absolute dry mass of the fiber), CPAM dry strength agent (average molecular weight 40W, solid content 1%, calculated based on the solid mass in the dry strength agent, the mass ratio of the dry strength agent to the fiber in the bleached softwood kraft pulp is 0.3:100, and the mass of the fiber in the bleached softwood kraft pulp is calculated based on the absolute dry mass of the fiber), natural vegetable oil-based softener (TS22 produced by Guanhong Chemical (Yangzhou) Co., Ltd., solid content 1%, calculated based on the solid mass in the softener, the mass ratio of the softener to the fiber in the bleached softwood kraft pulp is 0.15:100, and the mass of the fiber in the bleached softwood kraft pulp is calculated based on the absolute dry mass of the fiber), and stirred for 15 minutes respectively to obtain a pulp fiber suspension;

[0098] (3) The pulp fiber suspension was transported to the cylinder of the cylinder paper machine, the speed was controlled at 70 m / min, the movable arc plate of the cylinder paper machine was adjusted, the distance between the arc plate and the cylinder was 15 mm, and the opening angle of the arc plate was 20°, so that the pulp fibers were arranged longitudinally, and the wet paper web was obtained through the wire forming and pressing process, and the basis weight of the paper web was controlled at 18.0 ± 0.5 g / m 2 ;

[0099] (4) When the paper web passes through the wrinkling zone of the first drying section (drying temperature 95°C, moisture content 20%), adjust the wrinkling angle of the wrinkling scraper to 90° (the material of the wrinkling scraper is ceramic; the scraper holder angle of the wrinkling scraper is 15°; the scraper pressure of the wrinkling scraper is 18N / cm 2 ) The paper surface is slightly wrinkled, and the wrinkling rate is 13%;

[0100] (5) The paper web passes through the sizing section, where the upper and lower coating rollers apply sizing with a flexible butyl methacrylate emulsion (solid content of 20%, average molecular weight of 3W). The amount of sizing is controlled to be 0.5 g / m 2 ;

[0101] (6) Finally, after the second drying (105°C, 25s), calendering (calendering line pressure is 15N / mm; calendering temperature is 45°C; paper thickness after calendering is 30μm) and winding (winding tension is 50N; winding speed is 65m / min) stages, high-strength and high-flexibility paper yarn paper is obtained.

[0102] Example 5

[0103] (1) Commercial bleached softwood kraft pulp ("Moon" brand from Mercer Celgar pulp mill in Canada) was subjected to long fiber sticky pulping using three single-disc refiners in series, with a pulping concentration of 4.0%, a power of 60 kW, and a refiner throughput of 33 m 3 / h, the final beating degree of the bleached softwood kraft pulp is 35°SR, and the wet weight of the fiber is 10.8g;

[0104] (2) The bleached softwood kraft pulp after beating is pumped to the paper machine for mixing, water is added to adjust the pulp fiber mass concentration to 0.1% (the ratio of the mass of the fiber in the bleached softwood kraft pulp to the total mass of the bleached softwood kraft pulp and water is 0.1:100), and quaternary ammonium salt-modified microfibrillated cellulose with a substitution degree (based on amino groups) of 6 mol% (the mass ratio of the quaternary ammonium salt-modified microfibrillated cellulose to the fiber in the bleached softwood kraft pulp (based on the absolute dry mass of the fiber) is 3:97), PAE wet strength agent (average molecular weight of 8W, solid content of 1%, based on the solid mass in the wet strength agent, the mass ratio of the wet strength agent to the fiber in the bleached softwood kraft pulp is 1.2:100), bleached The mass of the fiber in the softwood kraft pulp is calculated based on the absolute dry mass of the fiber), CPAM dry strength agent (average molecular weight 40W, solid content 1%, calculated based on the solid mass in the dry strength agent, the mass ratio of the dry strength agent to the fiber in the bleached softwood kraft pulp is 0.3:100, and the mass of the fiber in the bleached softwood kraft pulp is calculated based on the absolute dry mass of the fiber), natural vegetable oil-based softener (TS22 produced by Guanhong Chemical (Yangzhou) Co., Ltd., solid content 1%, calculated based on the solid mass in the softener, the mass ratio of the softener to the fiber in the bleached softwood kraft pulp is 0.15:100, and the mass of the fiber in the bleached softwood kraft pulp is calculated based on the absolute dry mass of the fiber), and stirred for 15 minutes respectively to obtain a pulp fiber suspension;

[0105] (3) The pulp fiber suspension was transported to the cylinder of the cylinder paper machine, the speed was controlled at 65 m / min, the movable arc plate of the cylinder paper machine was adjusted, the distance between the arc plate and the cylinder was 10 mm, and the opening angle of the arc plate was 8°, so that the pulp fibers were arranged longitudinally, and the wet paper web was obtained through the wire forming and pressing process, and the basis weight of the paper web was controlled at 16.0 ± 0.5 g / m 2 ;

[0106] (4) When the paper web passes through the wrinkling zone of the first drying section (drying temperature 95°C, moisture content 20%), adjust the wrinkling angle of the wrinkling scraper to 83° (the material of the wrinkling scraper is ceramic; the scraper holder angle of the wrinkling scraper is 19°; the scraper pressure of the wrinkling scraper is 18N / cm 2 ) The paper surface is slightly wrinkled, and the wrinkling rate is 7%;

[0107] (5) The paper web passes through the sizing section, where the upper and lower coating rollers apply water-based polyurethane (solid content of 30%, average molecular weight of polyurethane of 2W) to the paper web. The amount of sizing is controlled to be 3.0 g / m 2 ;

[0108] (6) Finally, after the second drying (105°C, 25s), calendering (calendering line pressure is 15N / mm; calendering temperature is 45°C; paper thickness after calendering is 30μm) and winding (winding tension is 50N; winding speed is 65m / min) stages, high-strength and high-flexibility paper yarn paper is obtained.

[0109] Example 6

[0110] (1) Commercial bleached softwood kraft pulp ("Moon" brand from Mercer Celgar pulp mill in Canada) was subjected to long fiber sticky pulping using three single-disc refiners in series, with a pulping concentration of 4.0%, a power of 60 kW, and a refiner throughput of 33 m 3 / h, the final beating degree of the bleached softwood kraft pulp is 35°SR, and the wet weight of the fiber is 10.8g;

[0111] (2) The bleached softwood kraft pulp after beating is pumped to the paper machine for mixing, water is added to adjust the pulp fiber mass concentration to 0.1% (the ratio of the mass of the fiber in the bleached softwood kraft pulp to the total mass of the bleached softwood kraft pulp and water is 0.1:100), and quaternary ammonium salt-modified microfibrillated cellulose with a substitution degree (based on amino groups) of 9 mol% (the mass ratio of the quaternary ammonium salt-modified microfibrillated cellulose to the fiber in the bleached softwood kraft pulp (based on the absolute dry mass of the fiber) is 1:99), PAE wet strength agent (average molecular weight of 8W, solid content of 1%, based on the solid mass in the wet strength agent, the mass ratio of the wet strength agent to the fiber in the bleached softwood kraft pulp is 2.0:100), bleached The mass of the fiber in the softwood kraft pulp is calculated based on the absolute dry mass of the fiber), CPAM dry strength agent (average molecular weight 40W, solid content 1%, calculated based on the solid mass in the dry strength agent, the mass ratio of the dry strength agent to the fiber in the bleached softwood kraft pulp is 1.0:100, and the mass of the fiber in the bleached softwood kraft pulp is calculated based on the absolute dry mass of the fiber), natural vegetable oil-based softener (TS22 produced by Guanhong Chemical (Yangzhou) Co., Ltd., solid content 1%, calculated based on the solid mass in the softener, the mass ratio of the softener to the fiber in the bleached softwood kraft pulp is 0.15:100, and the mass of the fiber in the bleached softwood kraft pulp is calculated based on the absolute dry mass of the fiber), and stirred for 15 minutes respectively to obtain a pulp fiber suspension;

[0112] (3) The pulp fiber suspension was transported to the cylinder of the cylinder paper machine, the speed was controlled at 65 m / min, the movable arc plate of the cylinder paper machine was adjusted, the distance between the arc plate and the cylinder was 13 mm, and the opening angle of the arc plate was 17°, so that the pulp fibers were arranged longitudinally, and the wet paper web was obtained through the wire forming and pressing process, and the basis weight of the paper web was controlled at 20.0±0.5 g / m 2 ;

[0113] (4) When the paper web passes through the wrinkling zone of the first drying section (drying temperature 95°C, moisture content 15%), adjust the wrinkling angle of the wrinkling scraper to 83° (the material of the wrinkling scraper is ceramic; the scraper holder angle of the wrinkling scraper is 15°; the scraper pressure of the wrinkling scraper is 15N / cm 2 ) The paper surface is slightly wrinkled, and the wrinkling rate is 10%;

[0114] (5) The paper web passes through the sizing section, where the upper and lower coating rollers perform sizing with a flexible ethylene-acrylic acid copolymer emulsion (solid content of 20%, average molecular weight of ethylene-acrylic acid copolymer of 2.5W), and the amount of sizing is controlled to be 1.0 g / m 2 ;

[0115] (6) Finally, after the second drying (105°C, 25s), calendering (calendering line pressure is 15N / mm; calendering temperature is 45°C; paper thickness after calendering is 30μm) and winding (winding tension is 50N; winding speed is 65m / min) stages, high-strength and high-flexibility paper yarn paper is obtained.

[0116] Example 7

[0117] (1) Commercial bleached softwood kraft pulp ("GP" brand from Georgia-Pacific) was subjected to long fiber sticky pulping using three single-disc refiners in series, with a pulping concentration of 4.0%, a power of 60 kW, and a refiner throughput of 33 m 3 / h, the final beating degree of the bleached softwood kraft pulp is 40°SR, and the wet weight of the fiber is 9.8g;

[0118] (2) The bleached softwood kraft pulp after beating is pumped to the paper machine for mixing, water is added to adjust the pulp fiber mass concentration to 0.1% (the ratio of the mass of the fiber in the bleached softwood kraft pulp to the total mass of the bleached softwood kraft pulp and water is 0.1:100), and quaternary ammonium salt-modified microfibrillated cellulose with a substitution degree (based on amino groups) of 8 mol% (the mass ratio of the quaternary ammonium salt-modified microfibrillated cellulose to the fiber in the bleached softwood kraft pulp (based on the absolute dry mass of the fiber) is 1.5:98.5) and PAE wet strength agent (average molecular weight of 8W, solid content of 1%, based on the solid mass in the wet strength agent, the mass ratio of the wet strength agent to the fiber in the bleached softwood kraft pulp is 1.5:100), The mass of the fiber in the bleached coniferous kraft pulp is calculated based on the absolute dry mass of the fiber), CPAM dry strength agent (average molecular weight 40W, solid content 1%, calculated based on the solid mass in the dry strength agent, the mass ratio of the dry strength agent to the fiber in the bleached coniferous kraft pulp is 0.5:100, and the mass of the fiber in the bleached coniferous kraft pulp is calculated based on the absolute dry mass of the fiber), natural vegetable oil-based softener (TS22 produced by Guanhong Chemical (Yangzhou) Co., Ltd., solid content 1%, calculated based on the solid mass in the softener, the mass ratio of the softener to the fiber in the bleached coniferous kraft pulp is 0.15:100, and the mass of the fiber in the bleached coniferous kraft pulp is calculated based on the absolute dry mass of the fiber), and stirred for 15 minutes respectively to obtain a pulp fiber suspension;

[0119] (3) The pulp fiber suspension was transported to the cylinder of the cylinder paper machine, the speed was controlled at 65 m / min, the movable arc plate of the cylinder paper machine was adjusted, the distance between the arc plate and the cylinder was 14 mm, and the opening angle of the arc plate was 20°, so that the pulp fibers were arranged longitudinally, and the wet paper web was obtained through the wire forming and pressing process, and the basis weight of the paper web was controlled at 16.0 ± 0.5 g / m 2 ;

[0120] (4) When the paper web passes through the wrinkling zone of the first drying section (drying temperature 95°C, moisture content 15%), adjust the wrinkling angle of the wrinkling scraper to 75° (the material of the wrinkling scraper is ceramic; the angle of the scraper holder of the wrinkling scraper is 15°; the scraper pressure of the wrinkling scraper is 15N / cm 2 ) The paper surface is slightly wrinkled, and the wrinkling rate is 7%;

[0121] (5) The paper web passes through the sizing section, where the upper and lower coating rollers apply water-based polyurethane (solid content 30%, average molecular weight of polyurethane 2W) to the paper web, and the amount of sizing is controlled to be 0.5 g / m 2 ;

[0122] (6) Finally, after the second drying (105°C, 25s), calendering (calendering line pressure is 15N / mm; calendering temperature is 45°C; paper thickness after calendering is 30μm) and winding (winding tension is 50N; winding speed is 65m / min) stages, high-strength and high-flexibility paper yarn paper is obtained.

[0123] The paper yarn papers prepared in Examples 1 to 7 were subjected to quantitative and mechanical strength performance tests according to standards GB / T451.2-2002 and GB / T12914-2008, and compared with the performance of two commercial yarn papers. The results are shown in Table 1.

[0124] Table 1 Properties of paper yarn paper prepared in Examples 1 to 7 and commercial yarn paper

[0125]

[0126] From the data in Table 1, it can be seen that the high-strength and high-flexibility paper yarns of Examples 1 to 7 obtained by changing the beating degree of bleached softwood kraft pulp, the addition amount and substitution degree of cationic modified microfibrillated cellulose, the paper web basis weight and the amount of glue applied have various mechanical performance indicators far exceeding a commercial paper yarn. In addition, the high-strength and high-flexibility paper yarns prepared by the present invention are still insufficient in tensile index and aspect ratio compared with a commercial hemp yarn paper, but the high-strength and high-flexibility paper yarns prepared by the present invention are completely composed of 100% softwood pulp fibers, which are lower in cost than hemp fibers and have higher elongation.

[0127] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A high-strength and high-toughness paper for paper yarn, which is prepared by bleached softwood kraft pulp, cationic modified microfibrillated cellulose, cationic reinforcing agent and functional agent through cylinder screen forming, micro-wrinkling and sizing; the cationic reinforcing agent includes a wet strength agent and a dry strength agent, the functional agent is a softener; the glue used in sizing is a flexible polymer glue; the basis weight of the paper for paper yarn is 16-22 g / m 2 , aspect ratio is 6.5~7.4; The method for preparing the high-strength and high-tenacity paper yarn comprises the following steps: (1) mixing bleached softwood kraft pulp with water, cationic modified microfibrillated cellulose, a cationic reinforcing agent and a functional additive to obtain a pulp fiber suspension; (2) subjecting the pulp fiber suspension obtained in step (1) to cylinder-wire forming and pressing in sequence to obtain a paper web in which the pulp fibers are arranged longitudinally; (3) subjecting the paper web with pulp fibers arranged longitudinally obtained in step (2) to first drying, micro-creping, sizing, second drying, calendering and winding in sequence to obtain paper for paper yarn with high strength and high toughness; the glue used in the sizing is a flexible polymer glue; The cationically modified microfibrillated cellulose in step (1) is quaternary ammonium salt cationically modified microfibrillated cellulose; the degree of substitution of the cationically modified microfibrillated cellulose is 5-9 mol%, the diameter of the cationically modified microfibrillated cellulose is 200-500 nm, and the aspect ratio of the cationically modified microfibrillated cellulose is 50-300; the mass ratio of the cationically modified microfibrillated cellulose to the fiber in the bleached coniferous kraft pulp in step (1) is (1-5): (95-99); the beating degree of the bleached coniferous kraft pulp in step (1) is 30-55°SR, and the wet weight of the bleached coniferous kraft pulp is The wrinkling rate of the micro-wrinkling in the step (3) is 5-15%; the wrinkling blade is used to micro-wrinkle the paper web when it passes through the wrinkling zone of the drying section in the step (3); the material of the wrinkling blade is ceramic; the angle of the scraper holder of the wrinkling blade is 15-21°; the wrinkling angle of the wrinkling blade is 70-90°; the flexible polymer glue in the step (3) includes one or more of water-based polyurethane, acrylic ester emulsion, ethylene-acrylic acid copolymer emulsion and ethylene-vinyl acetate copolymer emulsion; the glue amount during the glue application in the step (3) is 0.5-3.0 g / m 2 .

2. The method for preparing the high-strength and high-tenacity paper yarn according to claim 1, comprising the following steps: (1) mixing bleached softwood kraft pulp with water, cationic modified microfibrillated cellulose, a cationic reinforcing agent and a functional additive to obtain a pulp fiber suspension; (2) subjecting the pulp fiber suspension obtained in step (1) to cylinder-wire forming and pressing in sequence to obtain a paper web in which the pulp fibers are arranged longitudinally; (3) subjecting the paper web with pulp fibers arranged longitudinally obtained in step (2) to first drying, micro-creping, sizing, second drying, calendering and winding in sequence to obtain paper for paper yarn with high strength and high toughness; the glue used in the sizing is a flexible polymer glue; The cationically modified microfibrillated cellulose in step (1) is quaternary ammonium salt cationically modified microfibrillated cellulose; the degree of substitution of the cationically modified microfibrillated cellulose is 5-9 mol%, the diameter of the cationically modified microfibrillated cellulose is 200-500 nm, and the aspect ratio of the cationically modified microfibrillated cellulose is 50-300; the mass ratio of the cationically modified microfibrillated cellulose to the fiber in the bleached coniferous kraft pulp in step (1) is (1-5): (95-99); the beating degree of the bleached coniferous kraft pulp in step (1) is 30-55°SR, and the wet weight of the bleached coniferous kraft pulp is The wrinkling rate of the micro-wrinkling in the step (3) is 5-15%; the wrinkling blade is used to micro-wrinkle the paper web when it passes through the wrinkling zone of the drying section in the step (3); the material of the wrinkling blade is ceramic; the angle of the scraper holder of the wrinkling blade is 15-21°; the wrinkling angle of the wrinkling blade is 70-90°; the flexible polymer glue in the step (3) includes one or more of water-based polyurethane, acrylic ester emulsion, ethylene-acrylic acid copolymer emulsion and ethylene-vinyl acetate copolymer emulsion; the glue amount during the glue application in the step (3) is 0.5-3.0 g / m 2 .

3. The preparation method according to claim 2, characterized in that: Calculated by the solid mass in the wet strength agent, the mass ratio of the wet strength agent to the fiber in the bleached softwood kraft pulp in step (1) is (1-2):

100.

4. The preparation method according to claim 2, characterized in that: Calculated on the basis of the solid mass in the dry strength agent, the mass ratio of the dry strength agent to the fiber in the bleached softwood kraft pulp in step (1) is (0.2-1):100.

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