KR100217303B1 - The production of high brightness recycled pulp - Google Patents

Abstract

The present invention relates to a method for producing recycled pulp having a high whiteness, and more specifically, to the dissociation step, oleyl alcohol derivative is added as a deodorizing agent to maintain whiteness initially, and to increase the number of carbon atoms in the flotation step during the deinking step. The present invention relates to a method for producing recycled pulp having excellent whiteness by adding saturated or unsaturated fatty acids of from 18 to increase collection properties.

Description

Manufacturing method of high white recycled pulp

The present invention relates to a method for producing recycled pulp having a high whiteness, and more specifically, to the dissociation step, oleyl alcohol derivative is added as a deodorizing agent to maintain whiteness initially, and to increase the number of carbon atoms in the flotation step during the deinking step. The present invention relates to a method for producing recycled pulp having excellent whiteness by adding saturated or unsaturated fatty acids of from 18 to increase collection properties.

Recently, the use of recycled pulp is increasing in terms of environmental and resource protection in the world, and the production process of recycled pulp generally consists of the following six processes.

The first step is a dissociation step of separating the paper into fibrous forms by treating the paper with chemicals and mechanical action in the pulp. The printing ink is peeled and dispersed from the fiber and a deodorant, which is a surfactant, is added. The second process is a shipbuilding process in which large foreign substances such as iron pieces, stones, and plastics contained in old paper are removed using a facility such as a cleaner. The third step is a deinking step of removing the ink dispersed and separated from the fibers out of the system using a flotation processor and a scrubber. The fourth step is a selection process for removing fine foreign substances such as sticky substances and large ink particles contained in the pulp by using a screen and a cleaner. In the fifth step, a polydisc filter, a screw press, or the like is used as a concentration step of compressing and concentrating the pulp concentration at 1 to 30% to increase the bleaching efficiency. The sixth process is a aging process to remove the chromophore of the fiber at a high temperature by using a bleaching agent such as hydrogen peroxide and sodium silicate to increase the whiteness.

The amount of ink that can be removed depends on the size of the ink peeled from the paper due to chemicals introduced during pulping, such as caustic soda and degreaser, pulping concentration, hydrogen ion concentration and mechanical stirring.

For example, in the dissociation process, the ink peeled from the fiber is removed from the flotation process used in the deinking process, where the deinking efficiency depends on the amount and size of the introduced air bubbles, and the size and the pulping of the ink attached to the air bubbles are added. Are affected by deodorant.

The degreaser during the production process of the recycled pulp serves to remove and disperse the ink together with air bubbles in the flotation apparatus used during the defrosting process by peeling and dispersing the ink from the fiber during the pulping process. Indeed, when the degreaser is added to the pulping process, the white paper may be separated by inks of different sizes even when the same paper is used due to the difference in penetration into the ink due to the difference in interfacial tension. In particular, in recent years, the printing method is offset ink printing in the case of newspaper paper, and the copy paper, etc. is changed to the molten ink printing method, so that peeling of ink from the fiber is difficult, and the paper quality is deteriorated due to the increase in slippery paper.

Accordingly, many efforts have been made to develop a method for producing a new recycled pulp that has excellent peelability of ink and excellent deinking efficiency.

In particular, Korean Patent Application Publication No. 89-2491 discloses an example in which recycled pulp is prepared by adding a fatty alcohol derivative as a deodorizing agent to a pulp to improve peelability of ink. In this case, a recycled pulp having a slightly better whiteness than the conventional method was prepared, but by adding only one type of degreaser to the pulp, it is necessary to adjust the peelability and ink size of the ink in the pulp. During the deinking process, it was not possible to satisfy the collection capability to collect ink together with bubbles in the flotation treatment machine.

In the present invention, as a result of a lot of efforts to improve the efficiency of each process, the oleyl alcohol derivative in the dissociation step in order to prevent the fall of whiteness due to ink refinement and to peel to a size suitable for removing the ink, and the ink together with the bubbles The present invention was completed by adding saturated or unsaturated fatty acids having 12 to 18 carbon atoms, respectively, in the flotation process during the deinking process in order to increase the collection properties.

Therefore, the present invention separates and adds a different type of degreaser suitable for each process, thereby improving the peeling and dispersibility of the ink and separating the ink particles into easy-to-remove ink particles in the flotation treatment machine, thereby improving the collection property and increasing the ink removal rate. It is an object of the present invention to provide a method for producing high-quality recycled pulp having excellent whiteness and low residual ink content.

In the present invention, in the method for producing recycled pulp, the oleyl alcohol derivative represented by the following formula (1) is added as a demulsifier in the dissociation step, and a saturated or unsaturated fatty acid having 12 to 18 carbon atoms is desorbed during the flotation during the deinking step. It is characterized by putting it as a mute.

At this time, x is an integer of 5-20, y is an integer of 7-15.

The present invention will be described in detail as follows.

The present invention separates and inputs a demulsifier of different components in each of the dissociation and deinking processes in a conventional regenerated pulp manufacturing method to separate and collect the ink particles in the ink particle size to facilitate separation and dispersion of the ink and to remove them in the flotation treatment machine. The present invention relates to a method for producing recycled pulp of high whiteness, which is excellent in whiteness and can contain less residual ink by improving ink removal rate.

The manufacturing method of the recycled pulp of the present invention will be described with reference to the dissociation step and the deinking step.

In the dissociation process, 0.5 to 1.5% by weight of caustic soda, 1.0 to 2.5% by weight of sodium silicate, and 0.1 to 1.0% by weight of deinking agent are added to the pulp of recycled paper such as newspaper paper, magazine paper, white paper, color white paper, and copy paper. Dissociate by

In general, as a demulsifier, fatty acids, fatty acid soaps, fatty acid derivatives, fatty alcohol derivatives, and the like are mainly used. Since there are differences in foaming properties, trapping properties, and foaming properties, appropriate ones may be selected. In particular, in the present invention, the fatty alcohol derivative having the best peelability of the ink during pulping in the dissociation process is used, and more preferably, the oleyl alcohol derivative represented by Chemical Formula 1 is used.

The oleyl alcohol derivative represented by Chemical Formula 1 has a strong permeability and is injected into a dissociation process to perform a strong ink peeling action. Therefore, since the size of the ink particles is largely separated to show whiteness superior to other degreaser in the pulp, excellent whiteness can be maintained initially. At this time, the oleyl alcohol derivative represented by the formula (1) is added to 0.1 ~ 1.0% by weight based on the dry weight of the material, if the addition amount is less than 0.1% by weight, there is a problem in peeling the ink, if it exceeds 1.0% by weight economical and There is a problem that excessive bubbles are generated.

Next, as the deinking process, the pulp treated in the dissociation step is diluted to 1.0-3.0% concentration with distilled water, followed by flotation and washing. In particular, in the present invention, when the pulp is added to the flotation treatment machine in the deinking process, saturated or unsaturated fatty acids having 12 to 18 carbon atoms are added. At this time, 0.1 to 1.0% by weight of saturated or unsaturated fatty acid is added to the dry weight, and if the amount is less than 0.1% by weight, there is a problem in collecting ink, and when it exceeds 1.0% by weight, problems of yield dropping and excess bubbles are caused. have.

This allows separation of the ink that has already been stripped off by the fatty alcohol derivative surfactant using the strong trapping by the ionic interaction of the saturated or unsaturated fatty acids used to produce pulp with superior whiteness than the conventional manufacturing process using only one type. It can manufacture.

Finally, bleaching is carried out for 30 minutes using a mixture of 1.0 to 2.0 wt% caustic soda, 1.5 to 3.0 wt% sodium silicate, and 1 wt% hydrogen peroxide for the purpose of increasing the whiteness.

Although this invention is demonstrated in more detail based on an Example, this invention is not limited to an Example.

Examples 1-8

A mixture of 80% by weight newspaper and 20% by weight magazine was used, and 0.5% by weight of caustic soda, 1.0% by weight of sodium silicate, and oleyl alcohol derivative were added to the composition of Table 1 in the dissociation process, and 15% The mixture was stirred using a high concentration dissociator (Daeil Corporation, Helico type) for 10 minutes at the stock concentration.

Subsequently, large foreign substances contained in the highland were removed using a cleaner, and the pulp thus prepared was diluted to 1.0% with distilled water, and soybean fatty acid (mixture of various fatty acids) was added to the flotation treatment machine according to the composition shown in Table 1 below. It was desorbed for a minute.

After decontamination, the mixture was concentrated to 30% using a concentrator, and then bleached for 30 minutes by mixing 0.5 wt% caustic soda, 3.0 wt% sodium silicate, and 1 wt% hydrogen peroxide.

Paper whiteness after each process was measured using ERIC 950 of Technidyne, USA, and the results are shown in Table 1 below. Also, the yield of the final product was calculated by measuring the dry weight of the filtered rejects during flotation. It was.

Example One 2 3 4 5 6 7 8 Notice Newspaper 80% + Magazine 20% Dissociation Process ⁽¹⁾ oleyl alcohol derivative (wt%, x / y) 0.3 (10/10) 0.3 (20/7) 0.3 (5/15) 1.0 (10/10) 0.1 (20/7) 0.2 (20/7) 0.3 (20/7) 0.3 (20/7) Whiteness after dissociation (%) 48.2 48.1 47.6 49.3 47.6 47.9 48.1 48.1 Deinking Process Soybean fatty acid (% by weight) 0.1 0.1 0.1 1.0 0.2 0.2 0.2 0.3 Whiteness after deinking (%) 54.0 54.4 53.8 57.5 54.5 54.0 54.2 55.5 Whiteness after bleaching (%) 61.0 61.2 60.9 65.0 61.5 61.0 61.5 62.7 Yield (%) 90.1 89.7 89.1 84.3 88.9 88.4 88.3 87.9 (1) Deinking agent used in the dissociation step (where x is the number of repeating units of ethylene oxide and y is the number of repeating units of propylene oxide)

Comparative Examples 1 to 5

In the same manner as in Examples 1 to 8, the oleic acid (C ₁₈ H ₃₅ COOH, unsaturated) and oleyl alcohol derivative was added to the composition of the following Table 2 upon dissociation, soybean desorption during the deinking process No fatty acids were added.

Comparative example One 2 3 4 5 Notice Newspaper 80% + Magazine 20% Dissociation Process Oleic acid 1.0 - 0.6 - - Soybean Fatty Acids - 0.6 - - - Oleyl alcohol derivative (wt%, x / y) - - - 0.4 (10/7) 0.4 (20/7) Whiteness after dissociation (%) 45.7 45.6 45.0 47.2 49.1 Whiteness after deinking (%) 51.0 50.1 50.2 50.7 51.3 Whiteness after bleaching (%) 57.7 56.9 57.2 57.6 58.5 Yield (%) 84.5 85.7 86.0 87.1 88.3

Examples 9-16

100% white paper, used in the dissociation process, caustic soda 0.5% by weight, sodium silicate 1.5% by weight, oleyl alcohol derivative is added to the composition of the following Table 3, high concentration dissociation for 10 minutes at 15% paper concentration ( Daeilki Corp., Helico form) was used for stirring.

Subsequently, large foreign substances contained in the highland were removed using a cleaner, and the pulp thus prepared was diluted to 1.0% with distilled water, and soybean fatty acid (mixture of various fatty acids) was added to the flotation treatment machine for 5 minutes by the composition shown in Table 3 below. It was desorbed.

After defrosting, the solution was concentrated to 30% using a concentrator, and then 0.5% by weight of caustic soda, 1.5% by weight of sodium silicate, and 0.5% by weight of hydrogen peroxide were mixed and bleached for 30 minutes, and the whiteness after each step was measured and shown in Table 3.

Example 9 10 11 12 13 14 15 16 Notice 100% white paper notice Dissociation Process Oleyl alcohol derivative (wt%, x / y) 0.3 (10/10) 0.3 (20/7) 0.3 (5/15) 1.0 (10/10) 0.1 (20/7) 0.2 (20/7) 0.3 (20/7) 0.3 (20/7) Whiteness after dissociation (%) 68.4 69.1 67.7 69.9 67.9 68.2 69.1 69.1 Deinking Process Soybean fatty acid (% by weight) 0.1 0.1 0.1 1.0 0.2 0.2 0.2 0.3 Whiteness after deinking (%) 79.0 79.0 78.5 83.9 79.0 79.2 79.7 80.8 Whiteness after bleaching (%) 83.5 84.0 83.2 88.5 83.8 84.1 84.6 85.3 Yield (%) 74.6 74.0 74.7 71.5 74.0 73.5 73.6 73.2

Comparative Examples 6 to 10

The same method as in Examples 9 to 16, except that the oleic acid (C ₁₈ H ₃₅ COOH, unsaturated) and oleyl alcohol derivative in the composition of the following Table 4 was added to the dissociation process, and deinking agent Soybean fatty acid was not added.

Comparative example 6 7 8 9 10 Notice Great white paper 100% Dissociation Process Oleic acid 1.0 - 0.6 - - Soybean Fatty Acids - 0.6 - - - Oleyl alcohol derivative (wt%, x / y) - - - 0.4 (10/7) 0.4 (20/7) Whiteness after dissociation (%) 65.5 65.9 65.0 67.2 69.4 Whiteness after deinking (%) 72.7 71.9 71.2 73.7 74.6 Whiteness after bleaching (%) 76.4 75.9 76.4 77.6 78.2 Yield (%) 72.0 72.5 72.3 73.1 73.5

As described in Tables 1 to 4 above, when oleyl alcohol derivatives, which are fatty alcohol derivatives, are added and fatty acids are added to the flotation during the deinking process, 3 to 4% GE in the case of newspapers, In this case, the whiteness can be increased by about 7 to 8% GE.

As described above, the present invention maintains excellent whiteness by injecting oleyl alcohol derivative in the dissociation step to maintain the excellent whiteness in the initial stage, and incorporating saturated or unsaturated fatty acids having 12 to 18 carbon atoms in the deinking step. It is possible to produce recycled pulp having a high whiteness by increasing it, which is very useful for solving the problem of deterioration of ink which has recently increased.

Claims (3)

In the method for producing recycled pulp, an oleyl alcohol derivative represented by the following formula (1) is added as a demulsifier in the dissociation step, and saturated or unsaturated fatty acids having 12 to 18 carbon atoms are added as a deinking agent in the flotation process during the demelting step. Method for producing a high whiteness recycled pulp, characterized in that. Formula 1

X is an integer of 5-20, y is an integer of 7-15. The method of claim 1, wherein the oleyl alcohol derivative is 0.1 to 1.0% by weight based on the amount of dry matter. The method of claim 1, wherein the saturated or unsaturated fatty acid is added to 0.1 ~ 1.0% by weight based on the dry material weight.