JPS5860088A - Method and apparatus for bleaching surface of paper in papermaking process - 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 relates to a method and apparatus for bleaching the surface of filter paper in a papermaking process.

In paper mills, conventionally, a bleaching process is carried out during the valving process using an apparatus as shown in FIG. That is, bleaching solution (b) is added to the raw material dehydrated with dehydration i (cL).
) and heated while mixing in the mixer (c), and then reacted in the reaction tower (d). Dilution water (e) was injected into the lower part of the reaction tower (dl) and the agitator (by force) The paper was stirred, then pumped using a pump (Gl), sent again to a dehydrator (α) in a similar device, and the above process was repeated six or more times to ensure complete bleaching throughout the entire thickness of the paper web. In the above, the bleaching solution includes chlorine in the first step and chlorine in the second step.
Caustic soda was used in the process, and sodium hybochlorite (NaOCt) or chlorine dioxide (ClO2) was used in the sixth process, which was expensive, and the equipment used to carry out the process was quite large.

The paper produced through the above-mentioned process is generally -L grade paper, but depending on the customer, it may not be possible to cover the entire thickness of the paper.
There is a demand for the production of inexpensive medium to low-grade paper that is bleached only on the front or back sides. However, the reality is that a method that bleaches only the front or back surfaces and can be produced at low cost has not yet been developed.

In view of the above circumstances, the present invention has been made with the aim of producing paper bleached only on the front or front and back sides in accordance with customer requests at a low cost. This invention relates to a method and apparatus for bleaching a 1 m paper web, characterized in that during the process or during paper web drying, a bleaching solution is applied to a 1 m paper web to bleach the surface of the paper web.

Hereinafter, embodiments of the present invention will be described with reference to Figure +f+7.

Figure 2 schematically shows the entire papermaking process.
is a head box, (2) is a dehydration process, (3) is a pressurization process, and (4) is a drying process, and in the present invention, bleaching process (5) is performed during the drying process (4). It is.

Note that (6) is a paper horse.

The specific apparatus used in the bleaching step (5) is as shown in FIG.

That is, smoothing rolls (7J (7)) are arranged above and below the paper web passage line so as to sandwich the paper web (6) in the width direction, and an appropriate number of bleaching rolls (7J) are placed in contact with each smoothing roll (7). A liquid application roll (8) is provided, and each of the upper and lower application rolls (8) located at the farthest position from the upper and lower smoothing rolls (7) among the basket cloth rolls (8) is placed in a liquid tank (
9) Immerse each roll in bleach solution 00 (7).
(Each application roll (8) by rotating 8J,
Smoothing roll (7)'j: KaiL bleaching solution (LO
The structure is such that it can be applied to the front and back surfaces of the paper web (6).

As the bleaching solution αQ, hydrogen peroxide (H2O2), zinc hydrosulfide (Z?LS204), calcium hypochloride (Cα(Oct)), sodium hypochloride (NaOCl), etc. are used.

In such a configuration, when the paper web (6) enters the drying process (4) after passing through the head box (1), the dewatering process (2), and the pressurizing process (3), the paper web (6) becomes as shown in FIG. It is bleached using the bleaching equipment shown in . That is, the paper rolls (71 (7)) hold the paper, and each of the 11 smoothing rolls (7) absorbs the bleaching solution Q in the liquid tank (9).
Since it is in contact with the application roll (8) side that is immersed in the
When each smoothing roll (7) rotates, the bleaching solution 00 in the liquid tank (!) is sequentially deposited and fed from each application roll (8) to the smoothing roll (7), It is applied to the top and bottom E11+, that is, the front and back sides of the paper web (6).The paper web (6) coated with bleaching solution θ0
is further bleached while being dried during the drying process and then wound up.

In this way, during the drying step (4), the front and back sides of the paper web (6) can be easily bleached using a simple device, making it possible to eliminate the need for conventional equipment that causes great damage. .

FIG. 4 shows another embodiment of the present invention, in which nozzle pipes 0υ0υ are arranged facing each other in the width direction of the paper web (6) at the edge of the paper web passing line. A bleaching solution (IO) was sprayed from each nozzle pipe 0υ toward the paper web (6) to bleach the front and back surfaces of the paper web (6).

Even when such a system is used, the same effects as those of the above embodiment can be achieved.

In addition, in each of the above-mentioned Examples, the drying process of the paper web (6) (
Although the case where bleaching was performed during the step 4) was shown as an example, the pressure step (3)
), or the front and back sides of the paper web may be bleached, but if necessary, it is possible to bleach the paper without using a device in which either the upper or lower side of the paper web passing line is located on one side. Of course, only one side of the animal may be bleached, and various other changes may be made without departing from the gist of the present invention.

As described above, according to the present invention, the bleaching solution is applied to the paper web surface during the pressurization process or drying process, so that
It is possible to eliminate the need for the conventional equipment that causes large losses, and to inexpensively produce paper that is bleached only on the surface of the paper that meets the customer's requests.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of the conventional example, Fig. 2 is a schematic diagram of the paper making process employing the present invention, Fig. 5 is a schematic diagram of the apparatus of the present invention, and Fig. 4 is a schematic diagram of the paper making process employing the present invention.
The figure is an explanatory diagram showing an embodiment of the device according to the present invention. (4)...Drying process, (5)...Bleaching process, (6)
... Paper fish, (7) ... Smoothing roll, (8)
...Coating 0-ru, (9)...liquid tank, 00-bleaching solution, (1υ...nozzle tube. Patent applicant Ishikawajima-Harima Heavy Industries Co., Ltd.

Claims (1)

[Claims] 1) A filter paper in a paper making process characterized by applying a bleaching liquid or the like to the paper web to bleach the paper web surface during the second and subsequent steps of "Paper web pressurization" How to bleach your face. 2) Smoothing rolls that clamp the paper web in the width direction are disposed above and below the paper web passing line during the process after the paper web pressurization stage, and each smoothing roll is bleached. 1. A four-side bleaching device for filter paper in a papermaking process, characterized in that a means for applying a solution is provided, and the bleaching solution can be applied to the surface of the paper by rotation of the smoothing roll. 3) At the lower part of the paper web passage line in the process after the paper web pressurization step, nozzle pipes for spraying one bleaching solution toward the paper web surface are provided facing each other in the width direction of the paper web. 1. A paper web surface marking device for use in a papermaking process, characterized in that it is configured to apply a bleaching solution sprayed from a nozzle pipe onto the paper web surface.