RU2249636C2 - Method of preparing pulp from corn stems - Google Patents

Abstract

FIELD: paper-and-pulp industry.

SUBSTANCE: corn stems are reduced to fragment, boiled, ground, dispersed, flattened, and dried to produce paper sheets. Boiling is carried out for 1.5-4 h at ratio of aqueous solution of reagent to corn stem material between 3:1 and 6:1 and temperature 120-200°C.

EFFECT: achieved high quality of pulp, improved environmental condition, and reduced expenses.

5 cl, 2 tbl, 7 ex

Description

BACKGROUND OF THE INVENTION

The present invention relates to a technology for the production of pulp using herbaceous plants, and more particularly, to a method for producing pulp from corn stalks.

The use of corn stalks as raw material for paper pulp allows to replace the import of wood raw materials, save foreign currency, increase agricultural income and ensure the production of high quality paper.

At present, taking into account the growing national income, Korea is the tenth country in the world for the production of industrial products (production of paper and cardboard is 5830000 tons per year), as well as the seventh consumer country of paper used for publications, newspapers, cardboard for book publishing, kraft paper and puffy soft paper. However, the total pulp production for paper production is completely (100%) dependent on foreign supplies. Since the development of pulp industry leads to a decrease in forest resources, the development of new materials for paper production is required. For this, it will be necessary to produce and process cellulosic materials from various plant species and improve their consumer value. The types of trees growing in Korea are not suitable for the production of pulp, wood harvesting in this country for the production of pulp is insufficient and therefore it is not possible to provide the required amount of raw materials for the production of paper pulp. In this regard, research reports often appear in order to find a new method for the pulp industry.

Typically, pulp for paper production is mainly obtained from wood. However, since the shortage of wood resources has been worsening all over the world recently, a serious problem has arisen for ensuring the production of pulp and paper without destroying forests and destroying the environment. As part of the program to solve this problem, one can note the attempts made to develop technologies for the production of pulp from non-woody plant fibers using one or two year old plants as the main materials. Significant efforts are being made to develop cellulose materials using herbaceous plants such as bamboo and agricultural waste, as well as to develop raw materials for pulp production in China, the Middle East and India, that is, in countries experiencing a shortage of forest resources. technological processes for the production of pulp using waste stems of sugarcane, usually destroyed after sugar production.

Generally speaking, non-woody plants contain a lot of pectin, a variety of hemicellulose and inorganic matter, as well as a little lignin. For the production of pulp from non-wood plants, chemical, semi-chemical, or mechanical methods are used to produce unbleached or bleached cellulose under very moderate conditions compared to wood materials. Non-wood pulp is characterized by the corresponding form of fibers, chemical composition, as well as the type and number of cells of non-fibrous materials. Therefore, paper made only from non-wood pulp or in an appropriate combination with wood pulp finds wider applications in accordance with strength, durability, electrical characteristics, gloss, dimensional stability and suitability for printing, and the number of such use cases is constantly growing.

Examples of non-woody plant materials are: inner layer of paper mulberry bark, flax, hemp, cotton and manila hemp, etc. In the art, attempts have already been made to develop methods for the production of pulp using raw materials such as sugar beet cake (as described in Korean Patent Laid-Open No. 84-005762), dry pine needles collected from fallen needles (see laid out Korean patent No. 91-3216), or rice stalks (see Korean Patents Laid-Open No. 98-9651 and 93-2604). In addition, Korean Patent Application No. 85-5895 discloses a method for producing pulp from tobacco stems.

According to the author of the invention, a method for producing pulp from corn stalks is not described in any document published before the filing date of this application.

Varieties of corn cultivated in rural areas are used as food for humans or as fodder for cattle. Most of the stalks of corn are used ground to fertilize the soil, although some of them are used to feed cattle. There is a serious need for alternative raw materials for the preparation of pulp in order to minimize the excessive costs of foreign currency and find the beneficial use of agricultural waste to increase agricultural income. There is also a need for high quality paper. Therefore, it is necessary to re-treat the corn stalks and increase their use in the production of cellulosic materials or other materials of the same purpose.

Therefore, the present invention attempts to produce new pulp from corn stalks and to produce paper having high quality and unique characteristics. Since currently, in most countries, paper production and dissolution of pulp is carried out by separating fibrous pulp from wood sources, more than 90% of the world pulp production is pulp.

In Korea, Korean paper was produced from mulberry bark for a long time, producing a purely Korean product with specific characteristics that differs from Western paper in physical properties. For example, Korean paper has much better durability, thermal insulation, and breathability.

Usually, to produce Korean paper, in October and November each year they collect paper mulberry bark, boil it in boilers and remove the top layer from it, leaving only a white bast. The outer layers of the bark are boiled for a long time in buckwheat liquor, and then beat off with a mallet to soften. Then the resulting decoction of paper mulberry is added to the debarking tub to produce sheet paper.

In the process of production of wood-based pulp, it is necessary to use a selective reagent composition that reacts when the wood material is exposed not to cellulose but to lignin. Since the process of obtaining pulp, from the point of view of environmental protection, is a combination of wastewater treatment and waste treatment, the pulp industry is considered a capital-intensive and energy-intensive industry using large-sized equipment and the consumption of a huge amount of water.

The chemical preparation of pulp involves the step of converting to pulp to remove lignin from the woody ingredients, as well as the step of bleaching and purifying the pulp to selectively remove residual impurities contained in the pulp. The specific chemical process for the production of pulp can vary significantly depending on the subsequent use and the desired quality of the finished pulp product. Typically, the pulp used to make paper is obtained from coniferous and deciduous wood. Such raw materials are processed into wood pulp by mechanical, chemical or semi-chemical method. The mechanical process for producing pulp consists of debarking, cross cutting, grinding, rough screening, fine screening, centrifugal cleaning, water separation, bleaching, washing, drying and packaging. While the chemical process for producing pulp consists of debarking, crushing, cooking, rough screening, fine screening, washing, centrifugal cleaning, water separation, bleaching, drying and packaging.

In particular, there are two types of pulp — pulp for paper making and soluble pulp. Soluble pulp is obtained by pretreatment and chemical cooking to obtain a high-purity cellulosic product and is used to produce various cellulosic polymer products and to produce cellulose derivatives having a high alpha-cellulose content of 90-98%. The semi-chemical method of pulping is a moderate chemical treatment followed by mechanical separation of the pulp fibers.

The sulfate method for removing lignin from wood involves the use of an alkaline cooking liquor containing nucleophilic groups such as —OH, —SH, and —S ₂ , which act on the lignin polymer formed by phenylpropane units to produce phenol hydroxyl groups forming a quinone methide that reacts with nucleophilic reagent, activating the sulfation reaction and thereby destroying the lignin polymer, which dissolves in an alkaline solution. In the acid sulfite method, hydrolysis of phenol ether bonds by H ⁺ ions is provided to produce a bisulfite carbon ion compound, whereby the lignin polymer is converted to a water-soluble lignosulfate. However, since in the implementation of the considered methods a cooking reagent is used that selectively reacts to the lignin polymer and not to other polymer wood ingredients, the cooking solution is a solution of strong alkali or acid. In addition, with these methods it is not possible to isolate varieties of high-purity fibrous cellulose, since some of the cellulose varieties decompose at a high temperature maintained in the range of about 150-170 ° C. to achieve a cost-effective lignin release rate. Therefore, the pulp for paper production has to be bleached to obtain a high whiteness using a method for selectively removing residual lignin with oxidation in at least five steps and / or using reduction and extraction with alkali, based on considerations of pulp yield and economic aspect.

SUMMARY OF THE INVENTION

The present invention is directed to a method for producing good quality pulp from corn stalks, whereby corn stalks can be used to produce high-quality pulp instead of ordinary wood pulp. The method of obtaining further includes the step of bleaching the pulp.

It is also an object of the present invention to provide a method for producing pulp from corn stalks into which other types of pulp can be added, such as wood pulp, pulp from waste paper or pulp from other herbaceous plants.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to a method for producing pulp using herbaceous plants and, in particular, to a method for producing pulp from corn stalks.

Eight varieties of corn are used as raw materials in the present invention: tooth corn, hard corn, sweet corn, popcorn, powdery corn, starchy sweet corn, waxy corn and soft corn, depending on the shape and properties of the grain. The fruits of corn are used for food, and silage from cut stems and leaves is used as animal feed. In addition, different varieties of corn are used as material for construction, fuel, filler, bedding, wicker sandals, medical materials, etc.

Traditionally, the main source of pulp is wood, which is formed in the form of cell walls of growing trees. The wood contains microfibers tightly laid in alternating order in a lignin matrix, which is similar in structure to cement, and partially connected with each other by chemical bonds that strengthen the wood. In a publication by Feudenberg et al., The decomposition products of wood were analyzed by hydrolysis, pyrolysis, substitution, oxidation, and reduction, and it was determined that wood has a different structure depending on the type of source, i.e. conifer, deciduous or herbaceous plant. Coniferous wood is used as an industrial material, and its use is based on the structure of elementary units of lignin contained in the walls of wood cells.

Regarding composition, the corn stalks of the present invention contain the most hemicelluloses and a reduced amount of lignin, while wood contains a large amount of cellulose and a large amount of lignin. For example, wood contains 45 wt.% Cellulose, 27 wt.% Hemicellulose, 28 wt.% Lignin and 3 wt.% Of other extracts. The corn stalk has elementary fibers 1-4 mm long, 20-40 microns wide and 5-10 microns thick.

The present invention is directed to a method for producing pulp from corn stalks, comprising the steps of grinding, cooking, pulping, paper forming and drying. This method of producing pulp from corn stalks is in many ways similar to the method of producing pulp from wood, but requires less stringent conditions for producing pulp due to the low content of lignin, etc. However, obtaining pulp from corn stalks takes quite a long time compared to the production of pulp from other herbaceous plants.

A method for producing pulp from corn stalks may further include a pulp bleaching step in which an oxidizing or reducing agent is usually used to bleach pulp. The method may further include a chlorination step using chlorine only in the first step of the process to remove residual lignin. The chlorination step makes lignin hydrophilic due to the reaction with an unsaturated aliphatic compound, fluorinated rubber preparations, or resinate. After chlorination, a thermal alkaline extraction step is carried out, which provides for the alkaline saponification of fatty acids, paraffins and other esters to give the free fatty acid in the form of soap. Fatty acid dissolves fluororubber preparations and decomposes lignin fragments. One of the most effective surfactants used in the alkaline extraction step is nonylphenol having branched glycol polyethylene. Like wood pulp, pulp from corn stalks is bleached with hypochlorite, bleached with chlorine dioxide or bleached with hydrogen peroxide to improve the whiteness of the product.

To improve and / or provide the required properties, pulp from wood, from grassy plants or from waste paper can be added to the pulp from corn stalks.

Alternatively, a water-soluble polymeric material can be introduced into the pulp, consisting only of corn stalks or additionally containing another pulp, in order to improve the properties of the pulp. In a preferred embodiment, polyvinyl alcohol or polyacrylamide can be used as the water-soluble polymer. a water-soluble polymer is introduced into the pulp to improve the surface condition and paper strength, expand application options and ensure its water resistance.

In the pulping process, additional ingredients such as starch, a paper hardening agent, a fiber expanding agent, a fluorescent bleach or a polymer electrolyte can be added. Preferred examples of polymer electrolyte may include polyamine, polyethyleneamine, polyethylene oxide, etc. Polymer electrolyte prevents fiber entanglement and disperses the pulp. Other additives make the pulp structure dense and provide fiber expansion, printing properties and paper opacity, as well as lower production costs. Examples of other additives include aluminum sulfate, calcium carbonate, kaolin, aluminum hydroxide, diatomaceous earth, lipid glucose, talc, carboxymethyl cellulose, diethylamine ethyl chloride, gum rosin, extraction rosin, and the like.

Among the steps for producing pulp in the high-pressure cooking step, it is preferable to use methods of pulping under pressure, such as sulphate cooking, sulphite cooking, alkaline sulphite cooking and soda cooking, since paper is not produced using the atmospheric pressure cooking method. The method of cooking at atmospheric pressure does not provide satisfactory boiling of the keratin layer and the inner fiber of the corn stalks, and, therefore, leads to significant losses of the cooking reagent.

The reaction conditions in the high-pressure cooking step are almost the same as in the four cooking methods above, with the exception of the type of reagent. For example, the alkaline sulfite cooking method and the soda cooking method are carried out under the same conditions, but using a different reagent. In the implementation of the sulfate cooking method, an aqueous solution of NaOH and Na ₂ S is used, in the implementation of the sulfite cooking method, an aqueous solution of Na ₂ SO ₃ and Na ₂ CO _{3 is used} , in the implementation of the alkaline sulfite cooking method, an aqueous solution of NaOH, Na ₂ CO ₃ and AQ ( anthraquinone), when implementing the method of soda cooking, only an aqueous solution of NaOH is used.

The cooking stage at high pressure is usually carried out under the following conditions: the reaction time is 1.5-4 hours; the reaction temperature is 120-200 ° C; the ratio (mass to mass) of the aqueous solution of the reagent and the feedstock to obtain pulp is selected in the range from 3: 1 to 6: 1. If the ratio (mass to mass) of the aqueous solution of the reagent and the raw material for producing pulp exceeds the above range, the use of the above chemicals leads to the dissolution of all fragile cellulose, so that strong fibers remain to increase the strength of the paper. Thus, the ratio of the aqueous solution of the reagent and the feedstock for pulp should be adjusted to achieve such an adequate level that will satisfy economic requirements.

The collected corn stalks are separated from the fleshy texture, chopped and torn to allow fiber cooking and, after removing the keratin layer and other impurities, are milled and torn. After that, sheet paper is made by forming sheets of paper from the dispersed pulp using a sheet-blowing machine, which is then sized, and dried.

Physical properties are measured for each type of paper obtained by sintering, sulphate cooking or alkaline sulphite cooking.

The largest specific volume is obtained for the pulp obtained by sodnar cooking only from the stalks of corn, which indicates that the fibrous structure of the pulp prepared by using the sodn cooking is very soft and forming a three-dimensional structure. The tensile strength test showed that the pulp obtained from sulfate cooking showed the highest tensile strength and boiled best. These results demonstrate that sulphate pulp consists mainly of fibrous tissue. Sulphate pulp has the highest bursting resistance and fracture resistance, while alkaline sulphite pulp has the highest tensile strength.

Table 1 Options Bleached Soda Cellulose Bleached sulfate pulp Bleached Alkaline Sulphite Pulp Softwood Bleached Sulphate Pulp Specific Volume (m ³ / g) 2.15 1.87 1.92 2.12 Stretch Factor (Nm ² / g) 17.52 28.82 23.12 39.40 Burst rate (kPa m ² / g) 0.08 0.15 0.12 0.41 Fracture resistance (number of double bends) 1.33 2 1,67 4.36 The rate of gap (mN m ² / g) 0.43 0.41 0.46 2.59

All sheets of paper obtained by mixing 40 wt.% Soda pulp from corn stalks, sulphate pulp from corn stalks or alkaline sulphite pulp from corn stalks with about 60 wt.% Bleached softwood pulp from softwoods (BSCCP) had significantly better physical properties compared to pulp obtained from corn stalks alone. Three types of cellulose, i.e. soda cellulose, sulphate cellulose and alkaline sulphite cellulose mixed with BSCCP showed an almost twice as high specific volume and burst resistance, at least almost seventy times greater fracture resistance and at least five times greater tensile strength than cellulose derived from corn stalks alone. This confirms the acceptability of the characteristics, economic benefits and the predicted long-term development in the field of pulp production from corn stalks.

table 2
Properties of paper sheets containing BSCCP (60 wt.%) And bleached pulp from corn stalks (40 wt.%) Options Bleached Soda Cellulose Bleached kraft pulp Bleached Alkaline Sulphite Pulp Softwood Bleached Sulphate Pulp A IN A IN A IN A IN The composition of the fibers (wt.%) 60 40 60 40 60 40 60 40 Specific Volume (m ³ / g) 1.98 1.89 1.98 2.12 Stretch Factor (Nm ² / g) 32.58 36.27 34.42 39.40 Burst rate (kPa m ² / g) 0.27 0.27 0.29 0.41 Fracture resistance (number of double bends) 77 85 78 4.36 The rate of gap (mN m ² / g) 1,69 2.08 1,52 2.59 Note. A: BSCCP B: cellulose from corn stalks

BEST MODE FOR CARRYING OUT THE INVENTION

A more detailed description of the present invention will be given below with reference to the following examples, which are illustrative and in no way intended to limit the present invention.

Reagents and materials

NaOH, Na ₂ SO ₃ , Na ₂ S and Na ₂ CO _{3 were} used as cooking agents in the present invention, and sodium hypochlorite (NaClO) and calcium hypochlorite (Ca (ClO) ₂ ) were used as bleaching agents.

As a raw material for the pulp used stalks of corn grown on a farm and completely dried in the shade. The dried stalks of corn were cut into 3-4 cm lengths, peeled of leaves and other unnecessary parts of the outer layer, and divided to remove the inner peel, i.e. fleshy texture, then crushed to the desired size, passing through a grinder and grater.

To obtain pulp, we used a three-liter vessel, a heating plate, a magnetic stirrer and a double steam boiler, which were used in atmospheric conditions, as well as a heated tank under a pressure of 10 kg / cm ² with agitation under increased pressure. An automatic agitator was used for washing and neutralization, and a special device was used to grind liquid pulp. For grinding pulp, a PFI type grinding apparatus was used (grinding conditions: pressure 1.8 kg / cm ² , clearance 0.3 mm), and a special standard sheet-making apparatus (manual sheet machine manufactured by TMI Inc., 173 mm in diameter). In this case, the radius of the filled tank was 17.3 mm, and the size of the sieve opening was 0.38-0.39 mm.

To shape the prepared paper sample and prevent warping on the dry surface of the paper sample, a thick non-woven fabric, ejector rollers and a twin-cylinder paper machine were used. Pulp characteristics were measured using a special volume meter and a tensile strength measuring instrument (Schopper instrument manufactured by Toyo seik Inc.), a burst resistance measuring instrument (a Mullen type measuring instrument manufactured by BFPerkin Inc.), measuring instrument for determining the resistance to fracture (manufactured by Timus Olsen testing machine Inc.) and a device for measuring tensile strength (measuring instrument Elmendorf (Elmendorf) for determining resistance Breaking the gap (Twing Alert Instrument Inc.).

Comparative Example 1

During an atmospheric experiment, 100 g of a sample of corn stalks (taken from a fleshy texture) was tested using NaOH with a concentration of 10% and Na ₂ SO ₃ with a concentration of 15% in a temperature range of about 150 ° C for 2, 3 and 4 hours, respectively . After filtering the boiled sample using a sieve with a mesh size of 100 mesh, the residue was precipitated in water to neutralize for about one day and dried at 80 ° C for 5 days. The dried product was intended to be used as a cellulosic material. Thus obtained finished product had a mass of 65.4, 63.2 g and 62.3 g as a result of treatment with 15% NaOH at 150 ° C for 2, 3 and 4 hours, respectively; and 68.34 g, 65.12 g and 62.7 g when treated with a 15% solution of Na ₂ SO ₃ at 150 ° C for 2, 3 and 4 hours, respectively. Thus, the quantitative yield was about 65%. One hundred (100) g of the boiled sample was filtered using a sieve having a mesh size of 100 mesh, and the residue was precipitated in water for about one day, followed by grinding paper pulp. The finished product was intended to be used as a cellulosic material, but paper was not formed from it.

To calculate the yield during cooking, a sample of corn stalks boiled under the appropriate cooking conditions was washed, torn in a fiber tearing apparatus at a speed of 3000 rpm, dried at 80 ° C for 5 hours, and weighed. The output during cooking was set by the following equation:

Example 1

When implementing the high pressure cooking method according to the present invention, 500 g of a sample of corn stalks were added to a rotary cooking apparatus with an electric heater (pressure 0-10 kg / cm ² , temperature 0-200 ° C, capacity 40 liters) and cooked at a liquid ratio ( mass to mass) from 4: 1 to 6: 1 (mass of an aqueous cooking solution to the mass of a dry sample) and at a maximum cooking temperature of 150 ° C for 1.5 to 4 hours, in accordance with the method of soda cooking.

In particular, at the first stage of the soda cooking method, 500 g of a sample was added to a rotating cooking apparatus with an electric heater (pressure 0-10 kg / cm ² , temperature 0-200 ° C, capacity 40 liters) and treated with a 15% NaOH solution at a fixed ratio of liquid (mass to mass) of 4: 1 (mass of an aqueous cooking solution to the mass of a dry sample) and a maximum cooking temperature of 150 ° C for 1.5 hours. It was found that the thickenings of corn stalks were poorly boiled and restored to their original state, which made it difficult to use the resulting material as a pulp. However, in the second stage of the soda cooking method, 500 g of the sample was added to a rotating cooker with an electric heater (pressure 0-10 kg / cm ² , temperature 0-200 ° C, capacity 40 liters) and treated with a 20% NaOH solution at a fixed ratio liquid (mass to mass) of 6: 1 (mass of an aqueous cooking solution to the mass of a dry sample) and at a maximum cooking temperature of 150 ° C for 3 hours. As a result, the corn stalks were well boiled, which allowed to obtain a pulp with a yield of 21-35 wt.%.

Example 2

A sample of corn stalks was soda-cooked using the first cooking liquid, consisting of a 14% Na ₂ SO ₃ solution and a 4% Na ₂ CO ₃ solution, at a fixed liquid ratio (mass to mass) of 4: 1 (mass aqueous cooking solution to the mass of the dry sample), and a maximum cooking temperature of 150 ° C for 2 hours. A sample of corn stalks did not boil properly to produce cellulose. Therefore, the sample of corn stalks was subjected to soda cooking using a second cooking liquid, consisting of a 28% Na ₂ SO ₃ solution and an 8% Na ₂ CO ₃ solution, at a fixed ratio of liquid (mass to mass) of 6: 1 ( the mass of the aqueous cooking solution to the mass of the dry sample), and the maximum cooking temperature of 150 ° C for 4 hours. As a result, the corn stalks were well boiled, which allowed to obtain a pulp with a yield of 26-41 wt.%.

Example 3

The same procedures were carried out as described in Example 1, except that 500 g of a sample of corn stalks were soda-cooked using a cooking solution consisting of a 10% solution of NaOH, a 20% solution of Na ₂ SO ₃ , 4 % solution of Na ₂ CO ₃ and 0.1% anthraquinone, with a fixed ratio of liquid (mass to mass) of 6: 1 (mass of an aqueous cooking solution to the mass of a dry sample) for 3 hours. The cellulose yield was approximately 23-38 wt.%.

Example 4

The same procedures were performed as described in Example 1, except that 500 g of a sample of corn stalks were sulphate cooked using a cooking solution consisting of a 20% NaOH solution and a 15% Na ₂ S solution, with a fixed the ratio of liquid (mass to mass) of 6: 1 (mass of an aqueous cooking solution to the mass of a dry sample) for 1.5 hours. The cellulose yield was approximately 25-32 wt.%.

Example 5

First pulp grinding and paper making

Thirty (30) g of boiled dry sample was precipitated in water at a concentration of 10% (mass to mass) for at least 2 hours and added to a grinder — a PFI grinder (grinding conditions: pressure 1.8 kg / cm ² , clearance 0.3 mm), followed by grinding sulfate pulp at 500 rpm or alkaline sulfite pulp at 1100 rpm to obtain 40. SR (Schopper-Riegler).

Example 6

Pulp bleaching

Sodium hypochlorite (NaClO) and calcium hypochlorite (Ca (ClO) ₂ ) were used as a bleaching agent, and sodium hydroxide and sodium silicate were added to them to obtain a pH value of 9-11. The concentration of pulp was in the range of 4-6% at a reaction temperature of 40 ° C, and in the range of 10-16% at 35 ° C.

After the stage of bleaching the pulp, the remaining alkaline component was extracted, reaching a concentration of pulp 10-20% at 45-80 ° C for 1-2 hours.

The types of pulp obtained in the examples were processed into sheets of paper using a special sheet-making apparatus (manual sheet-making apparatus manufactured by TMI Inc. 173 mm in diameter).

Example 7

We measured the physical properties of four varieties of cellulose (pulp), i.e. soda cellulose, sulphate cellulose, alkaline sulphite cellulose and sulphite cellulose obtained using the above examples, in which physical properties were measured. To improve physical properties and expand the use of pulp from corn stalks, every 40 wt.% Of these individual types of pulp was mixed with about 60 wt.% Bleached sulphate pulp from coniferous wood. After that, measurements were made on cellulose samples to determine the specific volume, tensile strength, burst resistance, fracture resistance and tear resistance. The results are presented in tables 1 and 2.

As described above, the present invention provides a method for producing pulp, in particular a method for producing pulp from corn stalks, comprising the steps of cooking, washing, sieving, separating water, bleaching, grinding paper pulp and drying, carried out under mild conditions, which have a negligible environmental impact. The use of corn stalks as raw materials for paper pulp eliminates the import of wood raw materials, saves foreign currency, increases agricultural income and helps to produce high-quality paper.

Claims (5)

1. The method of obtaining pulp from corn stalks, which consists in grinding corn stalks, boiling, grinding, dispersing, forming paper and drying the resulting sheets of paper, and cooking is carried out at a ratio of an aqueous solution of the reagent to the material of the corn stalks, from 3: 1 to 6: 1, at a reaction temperature of 120-200 ° C for 1.5-4 hours 2. The method according to claim 1, characterized in that the pulp is further bleached. 3. The method according to claim 1, characterized in that carry out sulfate cooking, sulfite cooking, alkaline cooking or soda cooking. 4. The method according to claim 1, characterized in that a water-soluble polymer material containing polyvinyl alcohol or polyacrylamide is introduced. 5. The method according to claim 1, characterized in that they additionally introduce an additive containing starch, an agent for hardening paper, an agent for expanding fibers, a fluorescent bleach or a polymer electrolyte.