SU1261996A1 - Method of producing paper - Google Patents

Abstract

The present invention relates to a method for producing paper and permits an increase in the absorbency of the paper while retaining its moisture resistance. f Unbleached sulphate pulp is ground to 16 ° IlP and a solution of compound A1 (CA) is added to it during the "spin-off" 20-40 minutes before the paper is bled. The CA consumption (recalculated) is 0.5-2.5% by weight of absolutely dry fiber. 30-120 seconds before the paper is poured into the mass, without turning off the agitators, add 1 n. a solution of Na hydroxide to a pH of 6.0-9.5, then paper is poured, pressed (L and dried. As CA use potassium alum, A1 sulphate or with their mixture. 2 Cp f-crystals. 7 tab.

Description

1C

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One Ilcobletenne belongs to the field of pulp and paper production and can be used in the manufacture of absorbent types of paper, which must also have the property of moisture resistance, such as paper for the inner layers of laminated plastic, as well as in the production of sanitary-hygienic types of paper. The purpose of the invention is to increase the absorbency of the paper while maintaining its moisture resistance. The essence of the method lies in the fact that when paper is obtained by successively introducing into the paper one weight of aluminum compounds and alkaline solution, pouring, pressing and drying the paper web of aluminum compound is introduced into the paper mass in 20-40 minutes, and the alkaline solution - in 30 -120 sec. Before the paper web is lowered, while aluminum potassium alum, aluminum sulphate and their mixture are used as aluminum compounds. The choice of the original alumina compounds and the duration of ripening of aluminum hydroxide (GSA) formed in bulk allows directionally adjusting the structure and composition of hydroxides in such a way that, together with an increase in interfluid bonds in paper, to provide a simultaneous increase in absorbency. The duration of the contact of aluminum compounds with paper pulp fibers (20-40 minutes) is necessary in order for the process of maturation and coarsening of hydroxide particles formed at the time of introduction of the solution into the mass, which causes an increase in the absorbency of the paper, basically ended. When aluminum compounds are supplied to the mass more than 40 min before the deposition on the grid, they form prematurely from polyhydroxo complexes of aluminum. At the same time, they are dehydrated and their structure is enlarged. As a result, deterioration of the binding properties of aluminum hydroxy compounds occurs and the strength of the resulting paper in a dry and wet state decreases. At the time of contact of the aluminum compounds with a fibrous mass of less than 20 min, the complete diffusion of such compounds into the wall of the cellulose fiber is not completed. Therefore, the distribution of side crosslinks in the paper sheet is uneven, causing a decrease in the strength of the samples. Example 1. In the first experiment, sulfate unbleached pulp of the grade NS-2 is milled in a laboratory roll to 6 ° ShR, aluminum sulfate solution is added to the ground pulp while moving. The amount of aluminum sulfate (in terms of) is varied in the range of 0.4–2.75% by weight of absolutely dry fibers. Aluminum sulphate solution is added with stirring 30 minutes before reflux. 20-150 seconds before pouring, add 1N to the mass, not including the agitators. Sodium hydroxide solution to pH 5-10. Samples of paper with a mass of 1 m 150 g are drained on an LOA-2 sheet casting machine. Samples were dried on a drying cylinder with a surface temperature of 1. the test results of the samples are presented in table. 1. As can be seen from the data given in table. 1, the introduction of aluminum sulphate in an amount of 0.5-2.5% with the subsequent introduction of sodium hydroxide 20-120 s before reflux at pH, 5 allows to obtain paper with high absorbency and moisture resistance. At the same time, the reduction in the consumption of aluminum sulfate going beyond the lower limit specified in the formula simultaneously leads to a decrease in the absorbency of ability and moisture resistance, and going beyond the upper limit to a decrease in absorbency. Deviation of the pH value from the specified limits reduces both. Example 1. In the second experiment, paper is obtained in the same way as the first experiment, but aluminum sulfate in an amount of 2-5% is introduced into pulp (ground cellulose) 15.20, 40 and 60 minutes before reflux, and sodium hydroxide solution is introduced in 20, 30, 120 and 130 s, and the outflow is carried out at pH 7. The test results of the samples are given in table. 2. Data table. 2 indicate that the introduction of the aluminum-containing compound into the pulp in less than 20 minutes before the paper samples are cast, does not result in paper with high moisture resistance and absorbing their ability. If the contact time AlJ (SO;) 3 with the fiber of that mass is reduced to 15 minutes, the capillary absorption of the samples is reduced by 26-29%, and the strength in the wet state is 38-57% compared to the level of these indicators for samples of the inventive invention. For example 2. The paper is prepared analogously to example 1, but aluminum potassium alum KAl (SO) is used as an aluminum compound in an amount of 0.3-2.8% by weight of absolutely dry fiber (in terms of 30 minutes to low tide.The results of tests of the obtained paper samples are given in Table 3. Dantd Table 3 indicates that aluminum potash alum, introduced into the paper weight of 0.5-2.5% to absolutely dry hair, provides increase the strength of paper in dry and wet conditions with a simultaneous increase in absorbency The efficacy of alum is almost the same as that of aluminum sulphate (Table D). Exceeding the volume of aluminum-containing compound reduces absorption, changing the time of interaction of GSA (hydroxy compounds with apcmin) with cellulose fibers to 10 and 150 s also reduces the effect, decreases 2–2.5 times the strength in the wet state and 1.2–1.3 times the absorption capacity. The pH of the mass before casting cannot be lower than 6, otherwise the strength of the paper produced is reduced compared with the strength of and pH 6-9.5 by 1.6 times. Higher than 9.5 pH values of the mass at low tide necessitate neutralization or washing of the paper. Example 3. The paper was prepared analogously to example 1, the difference is that the aluminum-containing compound is a mixture of aluminum sulfate and aluminum-potassium alum at the rate of 0.5–3.0% of the total content of the compound dried to the weight of absolutely dry fiberglass (in units of AljOj), ebb.Samples are produced. d t at pH 7.5. The level of this indicator is set for 30 s to low tide by entering into mass 1 and. NaOH solution. The results are presented in table. 4. Data table. 4 indicate that the mixture of aluminum sulfate and alum with a different ratio of these substances gives the same effect as each of the components separately. The excess of 2.5% content of aluminum-containing coepiaf (in terms of wt.% To absolutely dry fiber) leads to a decrease in the absorbency of the resulting paper. A mixture of aluminum-containing substances is introduced into the mass in the form of 1N. solution for 30 minutes before reflux. Example 4. To grind up to 16, sulphate unbleached pulp was added an almini sulphate solution in an amount of 0.5-1.5% by weight of absolutely dry fiber, counting on AljOj, and after 20 minutes. stirring, the alkaline solution is added - a solution of sodium aluminate to a pH of 7.5-9.5. Paper is poured out 30 seconds after adding the NaAlOj solution, i.e. formation of GSA in paper stock. The results are presented in table. 5. Analysis of table. 5 shows that sodium aluminate can be used as an alkaline agent to create the desired pH value without reducing the analyzed parameters. Example 5. Paper samples were obtained as in Example 4, the difference being that aluminum potassium alum was used as the aluminum-containing component, and sodium aluminate was used to adjust the pH of the assy. The results are presented in table. 6. Data table. 6 show that the introduction of aluminum-alum alum together with sodium aluminate into the paper pulp also makes it possible to obtain paper with a high absorbency, moisture and moisture resistance if the pH of the pulp is 7.4-9.0. Example 6. In the first experiment, paper was prepared according to a known method. To do this, in the same cellulose in examples 1–3, 15 minutes before the paper melt, nati aluminate is introduced in the amount of 2.5–5% by weight of absolutely dry fiber and the paper is converted.

those on A 1. Oj pH among; 8-9.5, which is ensured by adding 0.5 n to the mass. hydrochloric acid solution.

In the second ogalt, paper is prepared similarly to the first, but aluminum chloride is used as an aluminum compound. The outflow is carried out at a pH of 8-9.5, for which sodium hydroxide solution is introduced into the mass. The experiments were carried out under conditions close to production, i.e. without heat treatment (drying on a cylinder at.

The test results of the paper obtained in the first and second experiments, as well as the results of the test paper produced according to the previous method, are given in Table 7.

As a view, but from the data given in table. 7, the proposed method, compared with the known, allows an increase in the absorbency of the paper to be achieved while retaining moisture resistance.

Formula from gain

 . (/ paper preparation aid by successively introducing into the paper a mass of compounds of aluminum and alkaline solution, reflux, pressing, NIN and drying the paper web, so that it is, in order to increase the absorption ability of the paper while retaining its moisture resistance, aluminum compounds are introduced into the paper mass in 20-40 minutes, and alkaline solution - 30-120 seconds before the paper web is cast, while aluminum potassium alum, aluminum sulfate or aluminum mixture.

2. The method according to claim 1, about tl and h and y - y and with the fact that the compounds are

0 mini take in the amount of 0.5-2.5% by weight of absolutely dry fiber.

3. The method according to claim 1, wherein That the paper web is poured at pH

6.0-9.5.

It a b l and c a I

57.763.8 51.5 6, /, 5.3 7.94, B37 54.3 70.0 68.1 53.0 7.0 12.6 12.68.3M 53.873.0 73.2 50, 5 12.5 12.77.5 Zv 47.5 64.4 66.1 48.3 8.9 0.4 11.07730

Table 2 272930 36Sv39 MZv37 333029

Table 3

Table 4

Cashier I m, g

To PNP rna rtyulv most zl 5 mi, mm

(: Burst load;

in dry cocroKtaatt n.

when wet, n.

ERATOtlpOtmoCTb,%

Table 5

Table 6

Table 7

one

mass I m, g

Capillary flowability per S min, mm

Burst load:

in a dry state

n

when wet, n.8,4

Humidity, X1D, E

1261996

12.,

X

Continued table 7

150 150150150

130

37

3730

33

37

77; 3 57.5 80.8 60.6 79.2

13.3 8.214.2 8.614.0

17.2 14.5 17.5 14.1 17.6

Claims (3)

Claim 1. A method of producing paper by sequentially introducing into the paper pulp ₅ compounds of aluminum and an alkaline solution, reflux, press-. drying and drying of the paper web, characterized in that, in order to increase the absorbency of the paper while maintaining its moisture resistance, aluminum compounds are introduced into the paper pulp in 20–40 min, and alkaline solution in 30–120 s before ebb paper web when 15, potassium alum, aluminum sulfate or a mixture thereof is used as aluminum compounds. 2. The method according to π. 1, the fact that the compounds are 20 minia take in an amount of 0.5-2.5% by weight of absolutely dry fiber. 3. The method according to π. 1, characterized in that the casting of the paper web is carried out at pH 25 6.0-9.5. Ι Table! Sulphate aluminum consumption Alkaline administration time Bursting load in thawing, in dry soybean - Bursting load in wet n condition, n. PH at low tide Capillary absorbed in 5 minutes, mm solution Ά —-——- η . ¹ . ra s 5 6 7 | 8.5 J 10 5 6 7 9.5 TO 5 6 7 j 9.5 | 10 0.4 40 35.0 39.5 40.1 41.1 38,0 1.7 1.8 2, 1 2.0 2.1 28 27 29th 25 29th 0.5 thirty 31.7 52.9 54.0 .58.6 41.9 1.7 6.9 7.2 8.4 2.0 31 32 33 32 thirty 1.5 120 30,0 63.8 67.7 70.0 43.0 1.9 8.1 % uh 10.7 2,3 31 37 36 .34 _ 31 1.5 20 28,2 60.8 54,2 58.8 45.4 1.8 4.0 4.2 4.7 1.3 thirty 31 33 27 28 2,5 120 25.1 69.1 73.5 77.3 43.0 1.8 11.8 12.5 13.3 2.1 33 37 38 37 33 2.75 120 24.0 75,2 79,4 82,2 44.8 1.7 15.6 15,5 17.0 2,4 34 26 25 24 27 1,5 150 .30.3 63.0 66.3 71.0 41.5 1.8 4.4 4.2 6.2 1.8 27 27 29th thirty 29th table 2 Contact duration after addition of aluminum sulfate Explosive load in the dry CONDITION * N ₆ Bursting load in the wet state * n · Capillary retraction for 5 min, mm Contact Duration after alkali additives FROM 20 | thirty 120 | 130 20 1 30 120! 130 20 ?9 120 130 fifteen 57.7 63.8 75.0 51.5 6.4 5.3 7.9 4.8 27 27 29th thirty 20 54.3 70.0 68.1 53.0 7.0 12.6 12.6 8.3 34 36 38 39 40 53.8 73.0 73.2 50.1 7.5 12.5 2.7 Bj5 38 38 38 37 60 47.5 64,4 66.1 48.3 8.9 10,4 11.0 2.2 thirty 33 thirty 29th .1261996 Table 3 Consumption KA1 (SO ₄ ) ₂ ,% The time of introduction of NaOH before low tide, from pH at low tide Bursting cargo, n. Capillary absorption in 5 minutes, mm in dry condition in wet condition 0.3 40 6 42.0 2.0 26 0.5 thirty 6 57.5 3.2 thirty 1,5 thirty 9.5 71.3 11.2 34 2,5 120 9.5 80.8 14.2. 37 .2.8 120 9.5 81.1 16,4 24 1,5 10 6 60,4 6.4 26 1,5 150 6 70.0 5.1 29th 1,5 thirty 4,5 44,4 2.1 28 T Table 4 General The ratio (May.) A1 _g (SO ₄ ) ₃ and KA1 (SO ^ Bursting cargo, and. Capillary absorption in 5 minutes, mm consumption Alj (SO ₄ ) _3. + KA1 (SO ₄ ^,% Al ^ 0 j to fiber о in dry condition ... in wet condition  0.5 1: 1 60.6 8.6 sz 1,5 1: 2 74,2 12.1 37 2,5 2: 1 79.2 14.0 37 s oh 1: 1 80.2 14.3 22 - • T a b l and a 5 Consumption A1 _g (S0 ₄ ) _a ,% L1 _g O ₃ to fiber mass pH The time from the introduction of NaA10 ₂ to the outflow of paper, s Bursting cargo, n. Capillary 1 iep units LIVING magicians ig boo- in dry condition 1 Ιin wet ^! condition absorbency, mm 0.5 9.5 thirty 60, 1 8.6 29th 1,5 7.5 thirty 77.3 14.0 36 -B-o / Lk? .......... thirty BEHIND, .. 29th Table 6 Consumption KA1 (SO ₄ ) ₂ % A1 _g 0 ₅ to fiber the pH of the mass before the ebb paper The time from the introduction of NaAlO ₂ to the outflow of paper, s Breaking load, n. Capillary absorbency per 5 min, mm in dry condition in wet: CONDITIONS i ί ί 0.5 9.0 thirty 61.3 i mid co 29th 1.5 * 7.4 thirty 78.1 14.0 36 1,0 8.5 thirty 60.8 8.7 28 ... ..... - - ~ and Table 7 Indicators Paper obtained in a known manner according to the example. 6. 2.5% AIClj 5.0% AIClj 2.5% 5% ΝαΑΙΟγ to fiber to fiber NaAIO to fiber in units In units , to fiber in units A1 <0, A5A in units A1 _g 0 _e A ’A Weight 1 m *, g 150 150 150 150 Capillary rpktyvay — ’bridge” in 5 min, mm 21 16 . 24 thirteen 1 Bursting load} in dry condition, and. 59.7 81.1 57.9 80.0 in the wet state, i. 8.4 14.2 8.3 14.2 Moisture resistance,% 14.1 17.5 14.2 17.1 I2 _; . Continuation of table 7 The paper obtained by the proposed method according to examples 1 2 3 Al ^ SO,), KAI (SOD mix A1 _? (AML and KAI (SO,), 0.5% 2.5% 0.5% 2.5% 0.5% 2.5% PH 9.5 PH 9.5 pH 6.0 pH 9.5 pH 7.5 pH 7.5 . Λ Weight ! m, g 150 150 150 150 150 150 Capillary feed in 5 min, mm 32 37 thirty 37 33 37 Breaking load: in dry condition, n. 58.6 7.7 ', 3 57.5 80.8 60.6 79.2 in the wet state, n. 8.4 13.3 8.2 14.2 8.6 14.0 Moisture resistance.X 14.3 17,2 14.5 17.5 14.1 " 17.6