JPS60134097A - Papermaking method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides Il! 1 Paper Process Paper Process - This paper relates to a method for improving freeness.

Paper mills have been increasing the speed of paper machines and creating closed drainage systems for the purpose of saving energy, saving resources, and preventing end-of-ring pollution.

Under such circumstances, many paper mills use freeness improvers for the purpose of increasing the speed per second and reducing the amount of steam. Recently, with the increase in the speed of paper machines and the introduction of a closed system for white water, it has become difficult to sort the products.
- Due to the increased influence of shearing forces above the water and the progress towards closed white water systems, fine fibers, inorganic salts, anionic organic substances, etc. have accumulated in the white water1, and these have caused the release of chemicals. Effectiveness has begun to be harmed.

Conventionally, chemicals used as freeness improvers are generally susceptible to the above-mentioned inhibition, resulting in a large gap between static tests using clean water on a table and actual tests using white water. . Under this current situation,
We continued to investigate a good water warming property improver when white water containing interfering substances is mixed in, and found that chitosan had a significantly good effect, leading to the present invention.

Conventionally, polyamide polyamines, polyethyleneimine, Hofmann reaction products of polyacrylamide, Mannich reaction products of polyacrylamide, etc. have been used as drainage improvers, but they are generally susceptible to the influence of inhibitors α in white water. , polyamide polyamine is effective only due to its charge neutralization effect, +7), so it has no cohesive force against shearing force, and due to the recent trend toward closed white water, it cannot be used because it cannot respond to stratification. There are few factories.

Is polyethyleneimine sho #? Unable to respond to faster machine speeds,
Because it has disadvantages such as foaming and coloring, it has been replaced by the one described below. The Hoffmann reactant of polyacrylamide is
It does not have enough force to handle particularly strong shearing forces, and is inhibited by inorganic salts in white water, reducing its effectiveness.

The Mannich reaction product of polyacrylamide has a cohesive force against strong shearing force, so the number of factories using it tends to increase, but it has the disadvantage that it has little effect on reducing sheet moisture content, that is, steam usage meter. Under these circumstances, the emergence of a new filtering agent that has a cohesive force against shearing force, is effective in reducing steam consumption, and is less likely to be affected by white water has been awaited.

The chitosan used in the present invention is hardly affected by white water and is the best water-reducing agent that exhibits the effect of improving steam per second and reducing steam flow. It is surprising that the effect is good even when a small amount is added.

It also has the effects of a retention agent as a secondary effect. For example, it improves the yield of fine 11111 fibers, fillers, sizing agents, paper strength agents, etc., improves interlaminar strength, and reduces the burden of wastewater treatment.

The reason why chitosan has this effect is not yet fully understood, but the idea is described below.

Paper stock consists of a considerable amount of fine fibers and long fibers. Fines are the main cause of water draining and slowing down when sheets are formed on the Wiggy paper making machine. Freeness is used in the paper industry as a measure of water drainage; as freeness increases, water drainage increases.

Addition of a water reducing property improver causes fines to coagulate or coagulate, increasing the freeness of the paper stock and increasing the wire speed, thereby improving paper oil production.

Then, in the pressing process, the sheet is dehydrated to reduce the amount of steam used during drying, but as mentioned earlier, the water-reducing agent reduces the moisture on the wire, that is, the moisture before pressing, so the sheet The strength becomes stronger as the water content decreases, and the sheet does not collapse even under high press pressure.Also, since the fine particles are fixed on the long fibers, the flow path of the squeezed water is not blocked, so it is possible to increase the press pressure. It is possible to extract more water. However, if a polymer with strong water retention properties is used even when the freeness is dry, the agglomerated parts will be sticky and contain water, and when the water is squeezed out, the press pressure will block the water flow path. It is thought that the sheet moisture content will not decrease and the steam usage will not decrease.

Although chitosan does not form coarse aggregates, it has strong resistance to shearing force, so it exhibits high freeness even in high-speed paper machines that are subjected to strong shearing forces. In addition, by taking in water,
It has excellent performance as a water-reducing property improver, showing no tackiness after being mixed with fibers.

We think about chitosan as follows. Chitosan is a condensate of 2-aminoglucose linked to β-1,4 bonds, and is a polymer having a structure very similar to thealcellulose, a condensate of glucose linked to β-1,4 bonds. Therefore, its molecular structure has step-like linearity, and steric hindrance due to aminoglucose,
Also, due to its planar structure, the molecule is rigid. Since it is a molecule as described above, it electrostatically adsorbs to fibers and other anionic sites, and when the charge is neutralized, it becomes a cellulose analog, so it is thought that the aggregate does not have stickiness. Furthermore, because the molecules are rigid, they are not affected by salts or other interference in white water, and are thought to have strong resistance to shearing forces.

The chitosan used in the method of the present invention is obtained by a hydrolysis reaction of heating chitin with an alkali, and is made water-soluble by the presence of an acid such as acetic acid, sulfamic acid, or salt solution. Chitin exists as an organic skeletal material in arthropods, annelids, molluscs, etc., and is usually made from the shells of crabs or shrimps, washed and crushed, and then treated with diluted salt to remove calcium carbonate. After a short treatment with a concentrated alkaline solution,
After removing proteins and impurities, it is washed and dried.

According to this invention, water reducing properties can be improved by adding chitosan after the addition of each of the 11 chemicals is finished and mixed with white water in the paper manufacturing process. Water reduction properties can be improved by adding chitosan after mixing with white water. By adding chitosan after mixing with white water, it is possible to prevent the application of excessive shearing force after adding chitosan and to efficiently aggregate fines in white water. Specific locations for addition include under the seed box, before and after the fan pump, and before and after the screen.

The amount to be added as a freeness improver varies depending on the paper product and the paper machine, but 0.01 to 0.1% per valve is appropriate; Adding it to needles would be economically meaningless. Conventionally, it has been said that a 1% decrease in sheet moisture content before the drying process, that is, after the pressing process, reduces the steam consumption by 4 to 5%. In addition, in many paper mills that use freeness improvers, steam usage is reduced by about 8 to 10%.

The following examples are intended to explain this invention in more detail, but are not intended to be exhaustive.

Example 1 In order to compare the effect of improving freeness of chitosan and its relative freeness improver, each predetermined amount was added to valve slurry made from waste cardboard and diluted with tap water. After mixing, the freeness was measured according to JIS P, 8121 [Method for testing pulp freeness].

The chemicals used were as follows.

1. Chitosan, when dissolved at 1% in 1% acetic acid aqueous solution, 2o
It had a viscosity of ocp and a deacetylation rate of 81 mol%, and was used after being dissolved in an acetic acid aqueous solution.

2. Polyethyleneimine, (trade name of Borimin SN Badish) 3. Hoffmann reaction product of polyacrylamide, the molecule h↑ of polyacrylamide is 750,000, and the modification rate is 36 mol%.

4. Mannich reaction product of polyacrylamide, molecule 11
4.9 million, with a metamorphosis rate of 50 mol%.

Canadian Standard Freeness (CC) is shown below.

However, it is a slurry with a pH of 5.4 containing 3% of sulfuric acid.

According to this example, polyethyleneimine has low freeness and
It can be seen that the effect of shoja rise is low.

Example 2゜Example 1. However, in the same manner as in Example 1, the amount of oil and water was measured in the same manner as in Example 1. 3% of sulfuric acid was added.The solid temperature of the white water used was 1
,150 p p m, Cl0D1An1,290 p
pm1N4'J degree was 1,700μ.

Additive-free 298 cc Based on this result, chitosan is 4. For the system that sums: l-
It can be seen that 5-1 shows particularly good freeness, and that the effect is sufficiently exhibited even when ik'+l/z is added to (1;'t or iit).

Example 3 Example 2. The water-cooled 7111 regular product of the sheet sound water cooling was carried out using the crotch ball waste paper containing the white water used in the above] slurry and chemicals.

A sheet with a weight of 300 g/1♂ was made using the method (・2, 300 g/1♂), and was placed in an experimental calender (pressure 0.3 Kg).
The water content of the sheet was determined to be 7IIll by squeezing the sheet at a temperature of 12-min./as, d) degree.

Blank 55.9% This example shows that the effect of chitosan is particularly effective.

Example 4゜ Seeds for a white paperboard manufacturing factory using newspapers, magazines and waste paper as raw materials,
and white water to prepare pulp slurry, Example 2
．． 3, the Canadian Standard Freeness Value (Ca) and sheet moisture content were measured. In addition, the white water analysis value Gj1 solid content concentration was 2400 ppms, pH 6.1, and 1% sulfuric acid was added.

l) Canadian Standard Free Male value with turnip addition: 235 cc 2) Sheet moisture content: without addition of turnip: 235 cc This result also shows that the effect of chitosan is strong.

Procedures Amendment Written April 6, 1980 Patent Office P Officer Kazuo Wakasugi 1 Instructions in the case 1982 Patent Application No. 237779 2 Title of the invention Paper making method 3 Relationship with the case by the person making the amendment Patent applicant

Claims (1)

[Claims] A paper-making method for the purpose of improving freeness, which comprises adding water-soluble chitosan in an amount of 0.01 to 0.1% based on solid content during the paper-making process.