JPH04348195A - Felt detergent for papermaking - Google Patents

Abstract

PURPOSE:To provide the title detergent for continuous cleaning so as not to develop stains due to aluminum hydroxide and/or calcium carbonate leading to prevention of declining in papermaking felt performance due to contaminants. CONSTITUTION:The objective detergent for cleaning papermaking felts contaminated during papermaking process, a detergent liquor incorporated with an organic acid with chelating ability singly or its combination with an inorganic acid.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention focuses on aluminum hydroxide and calcium carbonate, which accumulate in the papermaking felt that transports wet paper in the press section of a papermaking machine and removes its moisture, degrading its performance. Related to cleaning agents that prevent stains.

0002

2. Description of the Related Art Generally, various chemicals are added to papermaking raw materials for the purpose of increasing paper strength, improving yield, improving paper texture, etc. The pH of aluminum sulfate, which is added to fix the sizing agent to the pulp fibers, changes due to the influence of shower water used for washing, and becomes water-insoluble aluminum hydroxide, which accumulates in the felt. ,adhere to. Furthermore, waste paper is used as a raw material for paper making, and calcium carbonate contained in the waste paper also adheres to and accumulates on the felt, significantly reducing the water permeability of the felt for paper making. Conventionally, physical methods and chemical methods have been used alone or in combination to remove stains from papermaking felt. Physical methods include high-pressure shower cleaning methods and the like. Chemical cleaning methods used inorganic acids and surfactants to dissolve and remove dirt.

0003

[Problem to be solved by the invention] In the case of a high-pressure shower using a physical method, the strong force of water causes hair removal on papermaking felt along with dirt, resulting in hair removal adhering to the paper and deterioration of paper quality. It turns out. For this reason, various chemical cleaning methods are commonly used. As cleaning agents, acids, alkalis, surfactants, etc. are used, and these are used alone or in combination. These methods dissolve and remove adhered dirt. Further, these are often used in strongly acidic or strongly alkaline conditions, which are not necessarily preferable in terms of workability and corrosion of paper-making machines. Efficiently removing such papermaking felt contaminants and reducing machine corrosion is a major issue in the use of papermaking felt during the papermaking process. The present invention is a papermaking felt cleaning agent for continuous cleaning to prevent aluminum hydroxide stains and calcium carbonate stains from occurring, rather than dissolving and removing adhered stains as in conventional cleaning methods. The purpose is to prevent a decline in the performance of felt for papermaking.

0004

[Means for Solving the Problems] As a result of intensive research into the above-mentioned situation, the present inventors found that the combination of an organic acid and an inorganic acid with a chelating effect effectively removes the water deposited on paper-making felt. The present invention was completed by discovering that aluminum oxide stains and calcium carbonate stains can be prevented. The present invention is a cleaning agent for cleaning papermaking felt that is contaminated during the papermaking process, and is a cleaning solution containing an organic acid alone or a mixture of an organic acid and an inorganic acid. As the organic acid, an organic acid having a chelating effect is preferable, and citric acid and malic acid are preferable, and these are used alone or in combination. As the inorganic acid, strong acids capable of lowering the solution pH with a small addition amount, such as hydrochloric acid, sulfuric acid, and sulfamic acid, are suitable.

By using a strong inorganic acid, the pH of the water in the felt after dilution with shower water can be adjusted. The reason why we decided to use an inorganic acid in addition to an organic acid is that the amount of precipitation of aluminum hydroxide and calcium carbonate stains, which are insoluble substances in water, reaches its maximum at pH around 7 and 11, respectively. Therefore, by using this inorganic acid, the pH of the solution can be lowered, and the precipitation of dirt can be prevented while the amount of dirt deposited is small. Furthermore, in places where metal corrosion is a problem, such as Yankee dryers, the problem can be solved by stopping the mixing of inorganic acids and increasing the amount of organic acids added. The organic acid concentration is 40% by weight in the case of citric acid and malic acid each alone.
is the upper limit, and in the case of a mixture, the total amount of both is 40% by weight.
is the upper limit. If it exceeds 40% by weight, insoluble matter will be formed, which is not preferable. The upper limit of the inorganic acid concentration is 50% by weight. Needless to say, each detailed combination will be determined by testing according to the papermaking conditions.

[0006]

【Example】

Example 1 (Precipitation prevention test) 2.00 g of various organic acids were weighed and dissolved in 50 ml of ion exchange distilled water. Using 0.5N-NaOH,
The pH was adjusted to two types, 7 and 11. Furthermore, ion-exchanged distilled water was added to bring the total volume to 150 ml. 0.1
Fine adjustment of the pH was performed using N-NaOH. pH to 7
aluminum sulfate (85.5g/l)
) to which the pH was adjusted to 11, calcium acetate was added dropwise and titrated until stable turbidity was confirmed. The pH during titration was always 7 and 11 using 0.1N NaOH.
I kept it. Calculate the gram equivalent and calculate the 1.00 gram equivalent of various organic acids.
Table 1 shows the results of calculating the amount of aluminum hydroxide stain and calcium carbonate stain that can be prevented from precipitating per gram.

[0007]

[Table 1]

As can be seen from Table 1, it has been found that phosphonic acid has a very large precipitation prevention effect on calcium carbonate stains, but this phosphonic acid is relatively expensive and furthermore contains phosphorus in its molecular structure. It was found that it could not be put to practical use as it would lead to eutrophication of water. Therefore, it has been found that the use of citric acid and malic acid, which have a large effect of preventing the precipitation of calcium carbonate and aluminum hydroxide, alone or in combination is excellent.

Example 2 (Metal Corrosion Test) The degree of metal corrosion was investigated in comparison with hydrochloric acid, which is mainly used in conventional chemical cleaning methods. Iron and SUS-304 manufactured by Nihon Test Panel Kogyo Co., Ltd. were used as test pieces, and the acid concentration was set to 1% pure content. The test piece was wiped with methanol and acetone to degrease it. After drying this test piece at 105°C, it was left in a desiccator and weighed. It was immersed in a 1% chemical solution that was aerated to constantly supply oxygen. The test pieces were taken out at regular intervals, washed, left to dry under the above conditions, and then weighed. After weighing, it was immersed in the chemical solution again. Tables 2 and 3 show the results of changes in the amount of corrosion caused by acids, and FIGS. 1 and 2 show graphs of the changes in the amount of corrosion.

0010

[Table 2]

[Table 3]

[0011]

Effects of the Invention As can be seen from the above explanation, the papermaking felt cleaning agent of the present invention is excellent in preventing the precipitation of stubborn papermaking felt stains such as aluminum hydroxide stains and calcium carbonate stains. It can be easily cleaned using the papermaking felt cleaning agent of the present invention without changing the papermaking felt cleaning agent of the present invention. In particular, when used in combination with an inorganic acid, the pH of the solution can be lowered, and the excellent effect of preventing the precipitation of dirt can be achieved while the amount of precipitation of dirt is small.

[Brief explanation of the drawing]

FIG. 1 is a graph showing changes in the amount of corrosion caused by acid on iron test pieces.

FIG. 2 is a graph showing changes in the amount of corrosion caused by acid on SUS-304 test pieces.

Claims (1)

[Claims] Claim 1: Use of a single solution or a mixture of an organic acid having a chelating effect of citric acid or malic acid, or a mixture of these organic acids, in a felt cleaning agent for cleaning papermaking felt contaminated during the papermaking process. 1. A felt cleaning agent for papermaking, characterized in that a felt cleaning agent for papermaking is used, either alone or in a mixed solution to which an inorganic acid group such as hydrochloric acid, sulfuric acid, or sulfamic acid is added.