RU2471911C1 - Method of obtaining colored paper - Google Patents

Abstract

FIELD: textiles, paper.

SUBSTANCE: invention relates to a method of obtaining colored paper, including the preparation of an aqueous dispersion of cellulose fibers and a natural dye solution - the product of the extraction of larch wood, containing 65-75 wt % quercetine and 25-35 wt % lignin-carbohydrate complex substances, dyeing of the cellulose fibers by their processing with the dye solution with its consumption of 0.5-0.8% of dry substance in reliance on the weight of absolutely dry fiber in dispersion, forming a paper web, which is different in preparing the additional dispersion of fibrillated cellulose fibers, only these fibers are subjected to dyeing, both dispersions are mixed to produce the paper pulp, while the amount of fibrillated cellulose fibers is 5-10 wt % of total amount of cellulose fibers in the paper pulp.

EFFECT: simplification and reduction in the cost of the process of obtaining the colored paper.

2 cl, 4 ex, 1 tbl

Description

The invention relates to technologies for producing paper dyed with natural dyes and can be used in the pulp and paper industry.

It is known that the coloring matter of natural dyes obtained by extraction of many plant materials is quercetin. However, the use of pure quercetin as a dye was not widely used due to its high cost.

A known method of dyeing paper by treating it with a solution of natural dye (SU 1470825, IPC D21H 1/46, publ. 07.04.89). This dye in the form of an amorphous powder is obtained by extraction of mulberry berries and the corresponding processing of the extract. The powder is dissolved in distilled water, the solution is filtered and the paper is processed by immersion in the resulting solution. The color of the paper, depending on the concentration of the solution, can be orange, orange-yellow and bright yellow.

The disadvantages of the method are the complex technology of dyeing, the use of additional equipment for the impregnation of paper and subsequent drying.

The closest analogue in technical essence and purpose to the present invention is a method for producing dyed paper, including the preparation of an aqueous dispersion of cellulose fibers and a solution of a natural dye - a larch wood extraction product containing 65-75 wt.% Quercetin and 25-35 wt.% Substances of the ligno-carbohydrate complex (RU 2173368, IPC D21H 21/28, published on 09/10/2001). The cellulose fibers in the dispersion are dyed by treating them with a dye solution in the presence of an inorganic salt at a dye flow rate of 0.5-0.8% dry matter based on the weight of the dry fiber in the dispersion. The temperature of the dispersion during processing is selected in the range of 60-100 ° C. Inorganic salt is added in an amount of 1.5-2.5% by weight of absolutely dry fiber. Excipients are added to the dispersion to form a pulp from which a paper web is formed.

The disadvantages of the method are due to the need to heat the pulp to 60-100 ° C, as well as the contamination of the paper with a non-functional inorganic salt.

A new positive result when using the proposed method is the simplification and cheapening of the process of obtaining colored paper due to the elimination of the operation of heating the paper pulp when processing the fiber with dye, reducing the level of contamination of the paper pulp and, accordingly, the paper with inorganic salt, as well as increasing the mechanical properties of the paper due to the use of pulp fibrillated cellulose fibers.

These results are achieved by the fact that in the method of producing dyed paper, including the preparation of an aqueous dispersion of cellulose fibers and a solution of a natural dye - an extraction product of larch wood containing 65-75 wt.% Quercetin and 25-35 wt.% Substances of the ligno-carbohydrate complex, dyeing cellulose fibers by treating them with a dye solution at a flow rate of 0.5-0.8% by dry matter based on the weight of the absolutely dry dispersion fiber, forming a paper web, according to the invention, an additional from a dispersion of fibrillated cellulosic fibers, is subjected to dyeing these fibers only, the two dispersions are mixed, the amount of fibrillated fibers is 5-10 wt.% of the total amount of cellulose fibers in the pulp. The treatment of cellulose fibers with a dye solution is carried out at room temperature.

The method in General is as follows.

The cellulose is ground to a predetermined degree of grinding and a dispersion is prepared with a concentration of, for example, 3% based on the dry weight of these fibers. A dye solution is also prepared. For its preparation, the amorphous raw quercetin powder containing 65-75 wt.% Quercetin and 25-35 wt.% Substances of the ligno-carbohydrate complex obtained by extraction of larch wood of Siberian or Daurian and subsequent processing of the extract is used. A predetermined amount of raw quercetin is dispersed in hot water, a solution of sodium carbonate is fed into the dispersion with stirring to a pH of 6.5-7.0, and a dye solution free of suspended particles is obtained. The dispersion of fibrillated cellulose fibers is diluted to a concentration of, for example, 0.5%, with stirring, a predetermined amount of the dye solution is fed into it and held for 2-3 minutes. Then both dispersions are mixed and get paper pulp. A paper web is formed from this mass using conventional technology.

In industrial conditions, all processes are carried out continuously using flowing apparatus.

The following examples illustrate the effectiveness of the proposed method.

Example 1

In order to obtain writing paper, a dispersion of cellulose fibers with a degree of grinding of 29 ° SR, a dispersion of fibrillated cellulose fibers, a yellow quercetin solution with a content of quercetin of 65 wt.% And a ligno-carbohydrate complex of 35 wt.% Are prepared. The estimated amount of dispersion of fibrillated fibers is treated with a dye solution with a given flow rate, kept for 2-3 minutes with stirring and mixed with a given amount of dispersion of cellulose fibers and get paper pulp. The content of cellulose fibers in it is 95%, microfibrillated fibers 5% of the total fiber mass. Dye consumption 0.65% based on total fiber weight. 3 identical yellow castings weighing 75 g / m ² are prepared from this mass by the usual method. The intensity of staining corresponds to the consumption of dye.

Example 2

Get cover paper for notebooks. The paper pulp operations are similar to those of Example 1. A pink-red dye solution is used. The content of cellulose fibers in the mass of 92.5%, fibrillated fibers of 7.5%. Dye consumption 0.80% based on total fiber weight. A pink-red color paper is obtained.

Example 3

Get colored paper with a filler, which is used as chemically precipitated chalk. The paper pulp operations are similar to those of Example 1. A brown dye solution is used. The content of cellulose fibers in the mass of 90%, fibrillated fibers of 10% of the total fiber mass. The content of chalk 10 wt.h. per 100 parts by weight fibers. The dye consumption is 0.5% based on the total amount of solids in the paper pulp. Castings have a light brown color.

Example 4

Castings weighing 75 g / m ² are obtained from cellulose fibers with a grinding degree of 29 ° SR without any additives.

Castings of the examples obtained from paper pulps that do not contain auxiliary substances. This is done to determine the effect on the strength characteristics of paper adding fibrillated fibers to its composition.

Under production conditions, those excipients are added to the paper pulp in the quantities required for the production of a given type of paper from the paper pulp compositions presented in the examples. The dyeing of the fibers does not affect these factors.

The table below shows the conditions for the production of castings and paper characteristics by examples.

Table The composition of the pulp for castings and characteristics of paper. Pulp composition and paper specifications Examples one 2 3 four Cellulose fibers, wt.% In the total mass of fibers 95 92.5 90 one hundred Fibrillated cellulose fibers, wt.% In the total mass of fibers 5 7.5 10 - Dye, wt.% Calculated on the total amount of solids in the paper pulp 0.65 0.80 0.50 - the content of quercetin in the dye, wt.% 65 70 75 - - the content of the ligno-carbohydrate complex in the dye, wt.% 35 thirty 25 - Filler, parts by weight per 100 parts by weight fibers - - 10 - Breaking length, m 5120 5200 5180 4850 The number of double bends 177 187 146 167 Tear resistance, mN 520 592 468 510 Bursting Resistance, kPa 226 236 194 214

Claims (2)

1. A method of producing dyed paper, including the preparation of an aqueous dispersion of cellulose fibers and a natural dye solution - an extraction product of larch wood containing 65-75 wt.% Quercetin and 25-35 wt.% Substances of the ligno-carbohydrate complex, dyeing cellulose fibers by treating them with a dye solution with its consumption of 0.5-0.8% by dry matter, calculated on the weight of absolutely dry fiber in the dispersion, forming a paper web, characterized in that an additional dispersion is prepared from fibrillated cellulos ozone fibers, only these fibers are dyed, both dispersions are mixed to produce paper pulp, and the amount of fibrillated cellulose fibers is 5-10 wt.% of the total amount of cellulose fibers in the paper pulp. 2. The method according to claim 1, characterized in that the treatment of cellulose fibers with a dye solution is carried out at room temperature.