RU2542562C1 - Method of obtaining microcrystalline cellulose for cardboard production - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: method includes reagent technological processing of initial raw material for 1-2 hours with possible additional stages of IR convective drying or homogenisation.

EFFECT: method is characterised by carrying out simple technological operations, environment friendliness, application of low-toxic reagents in minimal volume, scalability and reduction of production cost, does not require application of highly toxic reagents.

3 cl

Description

The invention relates to a method for producing microfibrillar cellulose fibers from plant materials, in particular sugar beet pulp, and can be used in the paper industry, in particular, in the manufacture of cardboard.

A known method of producing cellulose from flaxseed raw materials for use in the pulp and paper industry by loosening and cleaning the raw materials, washing, grinding, further soaking, thermomechanical processing, washing and bleaching, re-washing, spinning and drying. After thermomechanical treatment of the cellulose-containing material, it is possible to ripen in an alkaline solution, (patent RU 2343241 C1, publ. 10.01.2009).

A known method of producing cellulose from straw, which can be used in the pulp and paper industry in the production of various types of paper and cardboard. The method includes impregnation in a reactor and maceration of a straw section with an aqueous solution of sodium hydroxide with a concentration of 20-30 g / l in units Na ₂ O at a temperature of 30-80 ° C, the impregnated cross-section is kept at a given temperature for 30 minutes, the liquid phase is taken, heated water is added to the mass, the mass temperature is increased to 96 ° C, cooking is carried out for 2.5 hours (patent RU 2423570 C1, publ. 07/10/2011).

A known method of producing cellulose fibers from agricultural waste processing of cereals and cereals, including two stages of cooking, the first stage of cooking is carried out in an alkaline environment followed by separation of the cellulose-containing product, the second stage of cooking is carried out in an acidic medium with a mixture of peracetic acid, acetic acid and hydrogen peroxide in the presence of a stabilizer, which is used as a mixture of organophosphonates; the second stage of cooking is carried out in the presence of ozone (patent RU 2418122, publ. 05/10/2011).

A known method of producing cellulose from plant cellulose-containing material by sequentially locking the raw materials in an alkaline solution, thermomechanical processing, spinning, washing, bleaching, spinning, washing, spinning and drying (patent RU 2487206, publ. 10.07.2013).

The above disadvantages of the known methods, each separately or all together, reduce technological efficiency, increase the cost of production, cause difficulties in scaling production, do not allow to obtain a product with the claimed properties.

The closest to the invention in technical essence and the achieved result in terms of the method is a method for producing microfibrillar pectin-containing cellulose fibers, including steaming the fraction obtained by crushing the feedstock, three times washing, and subsequent bleaching with three washing, with possible additional stages of homogenization and infrared convective with (patent RU 2501325 C2, publ. 20.12.2013). The proposed method is characterized by sparing processing conditions for raw materials, however, it is multi-stage, has a higher cost.

The objective of the invention is to develop a consistent, without intermediate washes, wringes and unloadings, stepless reagent method for producing microfibrillar cellulose fibers using low toxicity reagents in a minimum volume, with the possibility of scalability and reduce production costs.

The technical result of the invention is to improve the quality of the finished product with a high degree of moisture retention, the ability to fully maintain its structure and properties during drying, which is widely used in the paper industry, in the production of biodegradable packaging materials, including cardboard. The addition of microfibrillar cellulose fibers obtained in this way in the pulp in the manufacture of cardboard significantly improves its quality indicators:

Breaking length, m Kink, the number of double bends Tear resistance, N / m ² Waste paper without additives 3670 334 320 Waste paper with the addition of microfibrillar cellulose fibers, 5% by weight 5870 1715 368

The technical result is achieved by the fact that the feedstock is crushed and fractionated to a particle size of 1.0-2.5 mm, reagent processing is carried out for 1-2 hours using tap drinking water as a process water with a total hardness of not more than 7 ° W, the total salt content of not more than 1000 mg / dm ³ , temperature 40-45 ° C, produce a smooth rise in temperature after 30 minutes from the start of steaming with the addition of an alkaline reagent in the form of a 45% aqueous solution of NaOH, to a pH of 9.6- 10.0, contribute 33% a solution of hydrogen peroxide when reaching a temperature of 55 ° C, measure the pH level, if necessary, adjust the pH level with an aqueous solution of NaOH to 9.6-10.0, continue to gradually increase the temperature to 75-80 ° C, maintain at a constant temperature of 75-80 ° C and pH 9.3-9.7 for 15-25 minutes, measure the pH level, if necessary, adjust the pH level with a 50% solution of acetic acid to a pH of 6.8-7.2, spin in a centrifuge or other squeezing equipment, washed in tap water at a temperature of 45-52 ° C for 5 minutes with constant stirring uu produce spin in a centrifuge or other squeezing equipment.

The technical result is achieved by choosing the optimal temperature and time parameters of the process and the minimum number of technological steps.

The method is implemented as follows.

In the production of microcrystalline cellulose fibers, sugar beet pulp is preferably used as a raw material.

The feedstock is ground and fractionated to a particle size of 1.0-2.5 mm.

The resulting fraction is subjected to reagent processing for 1-2 hours, optimally 1.5 hours with constant stirring. As process water use tap drinking water with a total hardness of not more than 7 ° W, a total salt content of not more than 1000 mg / dm ³ , a temperature of 40-45 ° C, optimally 45 ° C.

After 30 minutes from the start of steaming at a temperature of 45 ° C, a smooth rise in temperature is made, while adding an alkaline reagent in the form of a 45% aqueous NaOH solution to a pH of 9.6-10.0, optimally 9.8.

When the temperature reaches 55 ° C, a 33% hydrogen peroxide solution is added, the pH level is measured and, if necessary, the pH is adjusted with an aqueous NaOH solution to 9.6-10.0, optimally 9.8.

Then they continue to increase the temperature to 75-80 ° C, maintain at a constant temperature of 75-80 ° C and pH 9.3-9.7, optimally 9.5 for 15-25 minutes, optimally 20 minutes.

At the end of the alkaline steaming process, measure the pH level, carry out the correction with a 50% solution of acetic acid to a pH of 6.8-7.2, optimally 7.0.

Then spin in a centrifuge or other squeeze equipment.

Next, rinse in tap water at a temperature of 45-52 ° C, optimally 50 ° C for 5 minutes with constant stirring. Then spin in a centrifuge or other squeeze equipment.

The result is a wet granular product of white or light yellow color, without extraneous odors, with a mass fraction of moisture content of 85-95%, with a fiber size in the cross section of 0.1-1.0 μm, a length of 0.5-50 μm . The product can be subjected to infrared convective drying to a residual moisture content of 7-9%.

The resulting product may be subjected to an additional homogenization step to obtain a hydrogel. To do this, the resulting product is diluted with softened water to the required solids content, mixed until a homogeneous mass is passed three times through a homogenizer at a pressure of 200-300 atmospheres. The result is a hydrogel with a high degree of viscosity.

All three finished products can be used for the production of corrugated board and biodegradable packaging material for food and non-food products.

Claims (3)

1. A method of producing microcrystalline cellulose fibers, including grinding and fractionation of feedstock to a particle size of 1.0-2.5 mm, reagent processing for 1-2 hours using tap drinking water as process water with a total hardness of not more than 7 ° G, with a total salt content of not more than 1000 mg / dm ³ , a temperature of 40-45 ° C, a smooth rise in temperature after 30 minutes from the start of steaming with the addition of an alkaline reagent in the form of a 45% aqueous solution of NaOH to a pH of 9.6- 10, 0, making a 33% hydrogen peroxide solution when the temperature reaches 55 ° C, measuring and adjusting the pH level with an aqueous NaOH solution to 9.6-10.0, gradually raising the temperature to 75-80 ° C, keeping at a constant temperature of 75- 80 ° C and pH 9.3-9.7 for 15-25 minutes, measuring and correcting the pH level with a 50% solution of acetic acid to a pH of 6.8-7.2, spin in a centrifuge or other squeezing equipment, rinsing in tap water at a temperature of 45-52 ° C for 5 minutes with constant stirring, spin in a centrifuge or other squeezing equipment. 2. The method according to claim 1, characterized in that the resulting product is subjected to infrared convective drying to a residual moisture content of 7-9%. 3. The method according to claim 1, characterized in that the resulting product is diluted with softened water to the required dry matter content, mixed to obtain a homogeneous mass, passed through a homogenizer three times at a pressure of 200-300 atmospheres.