RU2755986C1 - Method for producing cellulose fluff - Google Patents

Abstract

FIELD: paper.SUBSTANCE: invention relates to the timber and pulp and paper industry and can be used for production of cellulose fluff from coniferous and foliiferous wood for production of disposable sanitary products, e.g., paper towels. Described is a method for producing cellulose fluff for paper towels from wood pulp, characterised by the fact that the wood pulp consisting of foliiferous or coniferous wood bleached in one stage is subjected to treatment with a BANZYME L90 enzyme for 5 to 10 minutes at a temperature of 50°C with an enzyme consumption rate of 0.05 to 0.2 g/kg of cellulose, dried to a moisture content of 45-55%, then crushed by aerodynamical dissolution of the cellulose for 7 to 15 s, and the process of mixing and separating the air suspension of cellulose fibres is executed by rotating rotor blades at a rate of 30 m/s with simultaneous formation of a uniform flow of the air suspension of cellulose fibres and supply thereof via a mass supply channel to a forming mesh resulting in a formed layer of fibres with a combination of fibres with a length of 0.5 to 1.5 mm from 20 to 30% and fibres longer than 1.5 mm from 70 to 80% for foliiferous wood and fibres with a length of 0.5 to 1.5 mm from 21 to 32% or fibres longer than 1.5 mm from 68 to 79% for coniferous wood, followed by applying the formed layer of antibacterial additive onto the surface in an amount of 1.5 wt.% at a content of the components: water solution of cluster silver - 0.5 wt.%, citric acid - 3.0 wt.%, hydrogen peroxide - 2.5 wt.% and distilled water - 94.0 wt.% by a sprayer at an angle of inclination during spraying of 90°, followed by drying under a pressure of 1.0 to 2.0 atm for 1 to 3 minutes at a temperature of 103 to 107°C with uniform migration of the antibacterial additive over the volume of the layer to a moisture content of 5 to 6.5%.EFFECT: production of a fluffed material with an antibacterial additive, without impurities, with maintained increased whiteness of the product (89.5% ISO) by means of use of one stage of cellulose bleaching, with reduced density, increased absorbency, for use in disposable sanitary products (e.g., paper towels).1 cl, 4 tbl, 6 ex

Description

The invention relates to the forestry and pulp and paper industry and can be used to obtain disposable hygiene products (for example, paper towels).

A composition for obtaining fluff pulp is known from the prior art according to patent RU2641136 (IPC D21H 21/22, D21H 17/37, D21H 17/36, 1321H 11/00, publ. 16.01.2018, USA). The composition consists of cellulose, a binding agent or binding agent, and a disintegrant. The composition is obtained on a paper machine in the form of a dried sheet, with or without subsequent treatment with a surfactant, and ground in a hammer mill. A superabsorbent polymer is used as a binder. After receiving the fluff (fluff pulp), tests are carried out for fractionation by fiber size, absorbency, compressibility and stiffness, liquid absorption time. The composition according to the patent RU2641136 contains three components (cellulose, a binding agent, a baking powder), and its production consists of four stages (obtaining a web, adding a baking powder (surfactant), grinding the web in a hammer mill (obtaining fluff), adding a binding agent (polymer)) ...

It is known in the art to use the BANZYME L90 enzyme to treat unbleached pulp (30-70% brightness) or waste paper before grinding to increase the life of the grinding equipment. Long-term treatment of the fiber with an enzyme preparation (40 min.) Leads to the process of fiber shortening, which limits the use of this development only for the production under consideration - obtaining a fluting-corrugated cardboard layer with water-repellent properties, a high density of 140 g / m ² and a low surface absorbency of 30-70 g / m ² (GOST 7377) [M.N. Spasennikov, V.A. Zhitnyuk, A.A. Shipigusev, G.F. Bylintseva, E.V. Belkin. An innovative approach to the use of enzymes in the production of high yield cellulose // Materials of the III All-Russian industrial scientific and practical conference "Prospects for the development of equipment and technology in the pulp and paper industry", Perm - 2015. - P. 33-37].

It is known from the prior art to use the enzymes Banzyme L90, Banzyme L90R, Resinase A2X, Resinase HT Fibercare D. BANZYME L90 to obtain CTMP from larch wood using enzymatic treatment to reduce the energy consumption for grinding by 15% and improve the mechanical properties of the resulting mass at a processing time of 2 hours and a temperature of 40-50 ° C [Kazymov D.S. Obtaining CTMP from larch wood using enzymatic treatment: abstract of dis. for the degree of Cand. tech. Sci., SPbGUPTD HSE, St. Petersburg, 2019]. Purpose and results: to develop the effect of enzymatic treatment for the development of the production of chemo-thermomechanical mass, using the features of larch wood raw materials with the preliminary extraction of extractives from wood raw materials.

From the prior art it is known to obtain southern softwood pulp of low coarseness (fluff pulp) according to international patent application US2019169799 (D21H 11/04; D21H 11/20; D21H 15/02; D21H 25/00; D21H 27/00; D21H 27/02 , publ. 06.06.2019, USA), chosen by the applicant as the closest analogue. Southern softwood pulp includes coniferous pine grown in the southern regions of the United States. Southern softwood pulp of low coarseness is obtained by debarking, grinding, kraft cooking or any, bleaching, forming into a sheet, dehydration, drying. The dried cellulose is tied into bales or rolled into a roll. A pine wood product grown in the southern regions of the United States, US2019169799 has good toughness. Significant disadvantages of this invention are: two stages of bleaching with chlorine dioxide according to ECF technology to achieve the required brightness, and the content of residual chlorine in the fluff pulp is not controlled; high content of long fibers 1.6-3.0 mm, which increases the density of the paper and reduces the absorbency.

The objective of the claimed technical solution and its technical result is to obtain a fluffed material with an antibacterial additive, with no impurities, maintaining the increased whiteness of the product (89.5% ISO) due to the use of one stage of pulp bleaching, with a reduced density, increased absorbency, for use in disposable hygiene products (for example, paper towels).

The task and the result is achieved by the fact that a method of obtaining fluff pulp from a web of wood pulp, characterized in that a web of deciduous or coniferous wood is treated with the BANZYME L90 enzyme for 5-10 minutes. at a temperature of 45-50 ° C with an enzyme consumption of 0.05-0.2 g / kg of cellulose and drying to a moisture content of 45-55%, and grinding is carried out by breaking up cellulose by an aerodynamic method for 7-15 seconds. on a combination of small fibers from 20 to 30% and large fibers from 80 to 70% for hardwood or from 21 to 32% of small fibers and from 79 to 68% of large fibers for softwood, followed by applying an antibacterial layer to the surface of a fluffed layer - additives for on the basis of an aqueous solution of cluster silver, citric acid and hydrogen peroxide at a ratio of the volume of the antibacterial additive to the volume of the fluffed layer 1: 11-1: 16, respectively, by a sprayer with an angle of inclination when spraying 90 °, drying under a pressure of 1.0-2.0 atm. within 1-3 minutes. at a temperature of 103-107 ° C with uniform migration of the antibacterial additive throughout the sample to a moisture content of 5-6.5%. In contrast to the prototype, fluff cellulose according to the claimed method contains an antibacterial product, the effectiveness of which is increased due to its deep penetration into the capillary-porous structure of cellulose fibers, which retained their integrity during the dissolution of the cloth subjected to enzymatic treatment. Only the combined action of enzymatic treatment and antibacterial additives in the indicated modes provide the technical result of the claimed method.

Example. The implementation of the method for obtaining paper towels is carried out by treating cellulose with the BANZYME L90 enzyme (cellulase enzyme preparation produced using genetically modified strains of Trichoderma reesei, the main active substances are endo-1,4-β-D-glucanase and cellobiohydrolase) for 5-10 minutes ... at a temperature of 45-50 ° C with an enzyme consumption of 0.05-0.2 g / kg of cellulose (for the convenience of operation, the enzyme preparation was diluted 100 times), drying to a humidity of 45-55%, cellulose dissolving is carried out by aeroforming using equipment [ patents RU2100508, RU94043433]: with a feed rate of a leaf made of deciduous, coniferous wood of 1.5 g / s, an air flow rate of 0.2 m ³ / s; with a speed of rotation of the rotor blades of 30 m / s; specific energy consumption in the disiergator 380 kJ / kg at a productivity of 50 t / day, with a room temperature of 25 ° C, an air humidity in the room of 75%, with a dissolution time of 7-15 s. on a combination of small fibers from 20 to 30% and large fibers from 80 to 70% for hardwood or from 21 to 32% of small fibers and from 79 to 68% of large fibers for softwoods, followed by applying an antibacterial additive to the surface of a fluffed layer at a ratio the volume of the antibacterial additive to the volume of the fluffed layer is 1:11 - 1:16, respectively, with a sprayer with an angle of inclination when spraying 90 ° and drying under a pressure of 1.0-2.0 atm. within 1-3 minutes. at a temperature of 103-107 ° C with uniform migration of the antibacterial additive throughout the volume of the sample to a moisture content of 5-6.5%, which is confirmed by measuring the moisture content at 10 points of the sample. Fibering was carried out in the same mode without pretreatment with the enzyme.

The cellulose web is fed into the mass feeding device through the diffuser-confuser channel. In the direction of movement, the cellulose bends around the rotor with blades installed in the body of the mass feeding device.

The rotation of the rotor helps to separate the cellulose into individual fibers and provides intensive mixing of the air suspension of the fibers, which guarantees an even distribution of the suspended fibers. The formed homogeneous flow of air suspension of cellulose fibers enters through the mass supply channel to the forming mesh. An air intake box is located behind the mesh, connected to a suction (exhaust) fan.

Examples (1-6), representing the influence of performance indicators, are shown in table. 1-4.

From the summary table it can be seen that only the declared wood raw material, consisting of hardwood pulp with the characteristics: whiteness 88.5% ISO, resin content - traces, residual chlorine content 0.03 g / l, lignin content less than 2%, ash content - 0, 50%, or softwood pulp with characteristics: whiteness 88.0% ISO, resin content 0.5%, residual chlorine content 0.03 g / l, lignin content less than 2%, ash content 0.55%, treatment with BANZYME enzyme L90 for 5-10 min. at a temperature of 45-50 ° C with an enzyme consumption of 0.05-0.2 g / kg of cellulose and drying to a moisture content of 45-55%, the decomposition of wood raw materials into fibers by aerodynamic hyusob for 7-15 s, providing a combination of small fibers from 20 up to 30% and large fibers from 80 to 70% for hardwood or from 21 to 32% of small fibers and from 79 to 68% of large fibers for conifers, followed by applying an antibacterial additive based on an aqueous solution of cluster silver to the surface of the fluffed layer, citric acid and hydrogen peroxide with a ratio of the volume of the antibacterial additive to the volume of the fluffed layer 1:11 - 1:16, respectively, by a sprayer with an angle of inclination when spraying 90 ° and drying under a pressure of 1.0-2.0 atm. within 1-3 minutes. at a temperature of 103-107 ° C to a moisture content of 5-6.5%, the tasks described above are provided.

From table 3 it can be seen that the best quality indicators of fluff pulp from hardwoods are presented in example 1: the strength of the test casting in tension is 1500 m, the breaking force is 7.5 N, the density of the test casting is 0.4 g / cm ³ . when treated with BANZYME L90 enzyme for 5 min. at a temperature of 50 ° C with an enzyme consumption of 0.20 g / kg of cellulose, with a mode of cellulose dissolution with a moisture content before dispersion - 55.0%, dispersion time - 7 s, fractional composition along the fiber length: 0.5-1.5 mm - 20%, more than 1.5 mm - 80%, when drying fluff pulp: pressure - 2.0 atm., Time - 3 minutes, temperature - 103 ° С, humidity after drying - 6.5%. When using softwood cellulose, example 4: the strength of the test casting at a stretch of 1490 m, the breaking force of 7.3 Η, the density of the test casting is 0.4 g / cm ³ , obtained by treatment with the BANZYME L90 enzyme for 5 minutes. at a temperature of 50 ° C with an enzyme consumption of 0.20 g / kg of cellulose, in the mode of dissolving cellulose with a moisture content before dispersion - 55.0%, dispersion time 8 s, fractional composition along the length of the fibers: 0.5-1.5 mm - 21 %, more than 1.5 mm 79%, with the drying mode of fluff pulp: pressure - 2.0 atm., time 3 min., temperature - 103 ° С, humidity after drying - 6.5%. Consequently, cellulose on hardwood has the best performance of fluff pulp under the same fiber preparation conditions and dispersion modes.

Thus, in contrast to the closest analogue of obtaining a web, fluff pulp according to the claimed method has a significant advantage in that both softwood and deciduous wood can be used to obtain fluff pulp with bleaching in one stage, and grinding is carried out by dissolving the web aerodynamically to a combination of small fibers from 20 to 30% and large fibers from 80 to 70% for hardwood or from 21 to 32% of small fibers and from 79 to 68% of large fibers for softwood. Treatment with the BANZYME L90 enzyme in these modes allows you to preserve the integrity of the fiber, which contributes to the preservation of the fibrous structure of the fluff layer, and to reduce the time of breaking into fibers (grinding) to 7-15 s. for processed cellulose, depending on the consumption of the enzyme. In the prototype, the method for producing the web has significant disadvantages in that the bleaching is carried out in two stages with chlorine dioxide using ECF technology to achieve the required whiteness, and the content of residual chlorine in the finished product is not controlled; includes a high content of long fibers of 1.6-3.0 mm, which increases the density of the paper and reduces the absorbency. In contrast to the prototype, fluff cellulose according to the claimed method contains an antibacterial product, the effectiveness of which is increased due to its deep penetration into the capillary-porous structure of cellulose fibers, which retained their integrity during the dissolution of the cloth subjected to enzymatic treatment.

In addition, the aerodynamic method for obtaining fluff pulp helps to reduce energy consumption and the amount of fresh water, in contrast to the traditional method of obtaining a web, declared in the closest analogue.

Example. Use of fluff pulp in disposable products.

As can be seen from table 4, fluff cellulose has the necessary absorbency, strength, lack of toxicity of the aqueous extract and foreign odors, neutral pH of the aqueous extract, contains an antibacterial additive, which ensures its use to obtain disposable hygiene products: paper towels.

Claims (1)

A method of obtaining fluff pulp for paper towels from wood pulp, characterized in that wood pulp consisting of deciduous or coniferous wood, bleached in one stage, is treated with the BANZYME L90 enzyme for 5-10 minutes at a temperature of 50 ° C with the consumption of the enzyme 0.05-0.2 g / kg of cellulose, dried to a moisture content of 45-55%, then crushed by breaking up cellulose by an aerodynamic method for 7-15 s, and the process of mixing and separating the air suspension of cellulose fibers is carried out by rotating the rotor blades at a speed of 30 m / s with the simultaneous formation of a uniform flow of air suspension of cellulose fibers and its flow through the mass supply channel to the forming mesh with the formation of a formed layer of fibers with a combination of fibers 0.5-1.5 mm in length from 20 to 30% and fibers longer than 1.5 mm from 70 to 80% for hardwood and fibers with a length of 0.5-1.5 mm from 21 to 32% or fibers with a length of more than 1.5 mm from 68 to 79% for conifers, followed by by applying an antibacterial additive to the surface of the molded layer in an amount of 1.5 mass. % with the content of components: an aqueous solution of cluster silver - 0.5 wt. %, citric acid - 3.0 wt. %, hydrogen peroxide - 2.5 wt. % and distilled water - 94.0 wt. % spray with an angle of inclination when spraying 90 °, followed by drying under a pressure of 1.0-2.0 atm for 1-3 minutes at a temperature of 103-107 ° C with a uniform migration of the antibacterial additive throughout the layer volume to a moisture content of 5-6, 5%.