SU1509737A1 - Method of determining hydrophobic property of adhesive based on rosin for sizing paper and cardboard - Google Patents

Abstract

The invention is intended for use in the manufacture of glued paper and paperboard in an acidic environment. The purpose of the invention is to improve the accuracy, intensify the process and simplify it while ensuring that it is possible to establish optimal sizing conditions. Rosin-based glue is successively precipitated from the coagulant aqueous suspension to various pH values of the suspension in the range of 4.0-5.5. Then, the resulting glue residue is dewatered by filtration under the action of hydrostatic pressure of a suspension column. The drainage characteristic is measured directly during the filtration process for each PH value. Filtration duration is used as a dewatering characteristic, the maximum value of which is taken as the desired value. 1 tab.

Description

This invention relates to methods for determining the hydrophobic ability of rosin-based adhesives for sizing paper and paperboard in bulk in an acidic medium, and can be used to investigate the suitability of adhesives in the pulp and paper industry.

The purpose of the invention is to improve the accuracy, intensify the process and simplify it while ensuring that the optimal conditions for the sizing process are established.

In the proposed method, the precipitation of coagulant adhesives is carried out sequentially to different pH values of the suspension in the range of 4.0-5.5, the measurement of the dewatering performance is carried out directly in the filtering process for each pH value, the duration of filtering is used as the dewatering performance and the determination of the desired value is carried out by the maximum value of a long filtering time.

In order to obtain a specific pH of the precipitated glue in the range of 4.0-5.5, the required amount of alkali (e.g. NaOH) or acid (for example, HCl) is injected into the initial glue solution or coagulant solution, and then precipitated glue coagulum.

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Sequential sedimentation of the coagulant glue to different pH values makes it possible to determine its optimum value at which the maximum filtering duration is observed. The latter characterizes the possibility of achieving the greatest hydrophobization effect of paper or cardboard under the conditions of sizing of the paper pulp draft

Filtration time maximums for suspensions of glue sediments are in the range of pH 4.0-5.5. At the same time, the duration of dewatering at pH below 4.0 or more than 5.5 has the smallest values that remain practically unchanged with further decrease or increase in pH which makes it impractical to carry out the precipitation of coagulant glue and reveal the duration of filtration beyond the limiting values of the specified pH range.

Example I (by a known method) The hydrophobic ability of rosin-based glue (7 variants) is determined by a known method by detecting the value of the limiting water retention of the adhesive sediment.

The preparation of a suspension of glue sediment, its dehydration by shaking, water retention, is performed as follows.

To one liter of distilled water is added a solution of completely saponified glue in an amount calculated by the formula

V

ml

1000

. .

.

to

where V is the glue consumption, deposition, ml; C 50 g / l - adhesive concentration,

g / l;

K is the number of acidic acid groups. in the adhesive, determined by conductometric method of analysis, mEq / g; 3.0 is the amount of mEq of the sizing agent contained in 1 L (mEq / L); 1000 - the volume of water ml

50

Example 2 The hydrophilizing ability of rosinol-based adhesives (the same 7 variants of adhesives as in example 1) is determined by the proposed method. For this purpose, a filter apparatus is used, consisting of 45 Büchner funnel installed in the neck of the flask, having an additional opening, which is hermetically connected through an intermediate edge to a pressure tank for water. In the lower part of the flask there is a tube with a drain valve installed in it. On a perforated partition of the Buchner valve is placed standard filter paper ltr

With stirring, 55 ash-free, labeled white are added.

a solution of coagulant (alumina) in an amount that provides a 1: 1 ratio of rosin and alumina to adjust the pH of the resulting glue suspension

tape), which ensures the retention of adhesive particles on its surface. By opening the intermediate valve, the flask is filled with water from

sediment up to 5.0, after which it is sequentially dewatered by filtration. First, the sediment is dewatered in a Buchner funnel through a paper filter under the action of the hydrostatic pressure of the suspension column, then in a special device under pressure at its two fixed values of P, 3.5 kg / cm and Prg 60 kg / cm

At the end of the dewatering by filtration under pressure, the precipitate is weighed, dried in the drying cabinet to a completely dry state, the dry residue is weighed and the water retention is determined for the specified pressure values.

 W

 - - R; --R,-

g 2 "

where W is the limiting water retention

adhesive sediment

g water / mEq saponified

acid groups; W and W - water holding values

sediment at pressure P and

g water / mg-squashed saponified

acid groups

establish the desired value of the limiting water retention of

The duration of all operations to determine the limiting water retention in three parallel experiments is 5 hours.

Example 2 The hydrophobic ability of rosin-based adhesives (the same 7 variants of adhesives as in example 1), using the proposed method, is used. For this purpose, a filter apparatus consisting of a Büchner funnel installed in the neck of the flask having A mouth is connected tightly through an intermediate faucet with a pressure tank for water. In the lower part of the flask there is a tube with a drain valve installed in it. On the Buchner funnel, a standard filter paper is placed ( type filters

ashless, marked white

tape), which ensures the retention of adhesive particles on its surface. By opening the intermediate valve, the flask is filled with water from the pressure tank at 20-2 ° C to a level that ensures wetting of the filter paper pd. Next, a sample of glue sediment is prepared,

15 ml of glue with a concentration of 25 g / l is diluted with distilled water to 135 ml. Then, with stirring, an aqueous suspension of glue is precipitated with coagulum (alumina) by adding 15 ml of alumina with a concentration of 25 g / l, which ensures a 1: 1 ratio of rosin and alumina and a total volume of the resulting suspension 150 ml. -5.5 during the precipitation of coagulant glue to the required value is carried out by adding an appropriate amount of alkali (NaOH) to the initial glue solution before precipitating the alumina. At this, the pH change interval is 0.2, and from 5.4 to 5.5 ,one"

The change in the volume of the glue sediment suspension when adjusting the pH by alkali is insignificant and does not take

The prepared suspension of glue sediment is uniformly mixed, divided into three equal parts of 50 ml each, and at 20 ° C are successively subjected to dehydration by filtration under the action of hydrostatic pressure of the column through a paper filter in a raven; Ke Buchner, To do this, release the tap with simultaneous activation of the stopwatch. dehydration and fixation of continuous ITI filtration is carried out upon reaching a volume of 45 ml in a measuring glass under a bleeder valve. The arithmetic average of three parallel measurements is taken as the actual value.

The end of the dewatering and the fixing of its filtration time can be determined by the moment of occurrence of the matt surface of the sediment, accompanied by the appearance of noise due to the beginning of the air through the precipitate, or when a certain column is reached by a column of suspension deposited above the filter surface.

As shown by the data obtained for each of the 7 variants of adhesives, the dependence of the length of the filter

0

five

about

0

five

five

0

five

from the pH of the suspension of glue sediment passes through m. maximum, i set the desired filtration value

The pH value corresponding to the maximum filtration time is optimal during the preparation of the glue sediment at the accepted cost ratio of rosin and coagulant. In practice, these conditions for the preparation of glue sediment correspond to the best mode of sticking of paper pulp and obtaining the highest degree of hydrophobicity in paper production.

At the same time, rosin-based adhesives, which have higher values of filtering time when compared, have better hydrophobicity,

The table shows the duration of filtration at pH 4.0; 5.0; 5.5, as well as at optimal pH values corresponding to the maximum duration of filtration; Additionally, the table shows the data characterizing the degree of hydrophobicity (sizing), assessed by water absorption by one-sided wetting for 60 s of paper weighing 70 g / m, made in laboratory conditions of bleached sulphite pulp with glue consumption of 1.0% of the dry residue of the fiber mass at the specified pH values

The mathematical processing of the table data and their analysis show that the correlation coefficient between the limiting water retention and the degree of sizing according to the known method is only 0.37, while according to the proposed method, at optimal pH values - 0, 92, which characterizes achieving higher accuracy.

The proposed method is, in addition, simpler, since there is no need for additional analysis methods: conductometric and weight analysis, pressure filtration and sludge drying, the availability of appropriate equipment and instruments.

In the proposed method, the measurement of the dewatering characteristic directly in the process

Filtration, depending on the type of rosin glue, can be carried out within 0.5-2.0 hours versus 5.0 hours for a known method, which characterizes the intensification of the process of determining the hydrophobic ability of rosin-based adhesives. At the same time, determining the conditions under which the maximum filtering time, additionally allows to determine the optimal sizing regimes of the pH of the suspension, the ratio of the consumption of rosin and coagulant to the paper pulp during the paper manufacturing process, which was not achieved by the known determining allowance hydrophobization adhesives ability to rosin-based.

Claims (1)

The invention The method of determining the hydrophobic ability of rosin-based glue for sizing paper and paperboard, including the deposition of glue from its aqueous suspension of coagulant. Dehydration of the precipitate by filtration under the action of hydrostatic pressure. a suspension column, measurement of the sludge dewatering characteristic and determination of the desired value from the measured characteristic, characterized in that increase the accuracy, intensify the process and simplify it while ensuring that the optimal conditions for the sizing process can be established, the deposition of the adhesive is coagulated successively to different values of the pH-suspension in the range of 4.0-5.5, the measurement of the dewatering performance is carried out directly in the filtering process for each pH value; filtration time.