JPS60134089A - Production of regenerated pulp from laminate old paper mixedpapermaking stock material - 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 invention relates to a method for producing recycled pulp for papermaking from papermaking raw materials, mainly wastepaper, including laminated wastepaper laminated with plastic film and metal foil.

A thin transparent plastic film is pasted on the printed surface of the paper to protect the printed surface and give it a glossy surface.)
In order to package milk and other beverages in paper containers, it has become common to apply metal foil, such as aluminum foil, to the paper surface forming the inner surface of the box.

On the other hand, in order to recycle the waste paper into valves for used paper, the waste paper is treated with a pulper, and the treated paper is fed into the retention tower from above and taken out from the bottom, storing it in the tower for 70 to 30 hours. The ink adhering to the paper is emulsified by the action of a deinking agent, and the material extracted from the tower is passed through a screen to separate foreign substances using a sieve mesh. , - Obtaining pulp through washing, bleaching, and washing was described in
It is publicly known from the publication No. 3-47904.

When producing pulp for papermaking by treating all waste paper with a pulper, including the above conventional method, the pulper disintegrates the waste paper into fibers, so the diameter of the holes in the soot strainer of the pulper is 3.
~io is simple. However, in order to disintegrate the waste paper into a fibrous state before passing through the holes of the strainer, it is necessary to let the waste paper flow in the pulper for a long time, and during that time,
Power costs are extremely high to keep the rotor rotating.

Furthermore, if the waste paper is mainly laminated waste paper, or if it contains two-layer waste paper, the plastic film, metal foil, or asphalt pitch attached to the paper during long-term disintegration may be removed from the paper. Some of the pulp is peeled off during the process, but some of it is crushed along with the paper and fragmented, and cannot be removed in the separation process due to the difference in sieve mesh and specific gravity after being extracted from the retention tower, and is left as is in the recycled pulp. This causes various troubles during paper making. For example, if finely crushed plastic film is mixed into the pulp, it will not only reduce the quality of the product, but also cause problems such as the plastic film softening due to heat in the paper machine and sticking to the paper making equipment. If fine fragments of aluminum foil or the like are mixed in, the problem arises that they come out on the surface of the paper and make it impossible to produce a product at all.

Therefore, when processing mainly waste paper, including laminated waste paper, with a pulper, the present invention changes the concept of the role of the pulper from the conventional one.In other words, instead of disintegrating the paper into fibers, it is used in a retention tower after processing with the pulper. It is only necessary to crush the plastic film or metal foil into coarse pieces that will not clog the pump, and this ensures that the coarse pieces of plastic film or metal foil are removed in the separation process using sieve mesh and specific gravity after being extracted from the silitention tower. The purpose of this method is to obtain recycled pulp that does not contain plastic film or metal foil, and at the same time reduce the power cost required to operate the pulper. A pulper equipped with a strainer is used to crush the paper pieces into coarse paper pieces that pass through the holes of the strainer, and the coarse paper pieces are stored in a retention tower for at least io hours to hydrate and swell the paper pieces into a fiber state in the tower. It is characterized by weakening the bond between the paper piece and the laminate piece, and then separating and removing the laminate piece using a screen with a hole diameter of 3 to 6 m.

Embodiments of the present invention will be described below with reference to the drawings.

Waste paper mixed with laminated waste paper is mixed with water, and the diameter is 10~
The waste paper is fed into a pulper equipped with a strainer having 4I0 square holes, and the waste paper is crushed into coarse pieces large enough to pass through the strainer holes by the shearing action of the water flow generated by the rotor rotating inside the vessel.

Incidentally, steam, chemicals that completely disintegrate the waste paper, deinking agent, whitening agent, etc. may be added to the pulper.

When waste paper is processed with a conventional pulper equipped with a strainer with a hole diameter of 3 to 1A, the residence time of the waste paper in the pulper is about 20 to 60 minutes. Since it is sufficient to crush the material to the extent that it passes through a 410 m hole, the residence time in the pulper is only 3 to 10 minutes, which is shorter than conventional methods to approximately A to 100 m, reducing power costs.

The coarse paper pieces crushed in the pulper have a concentration of 3 to 3%.
In this state, it is sent to Shishitsukuna J by a pump collector, concentrated to a concentration of /S to 30Qb by a thickener, and charged into a retention tower T from above. The liquid dehydrated in the thickener is passed through the ocean and stored in a storage tank S, and is supplied to the pulper when the pulper is at rest.This allows the added water, heat, and various chemicals to be circulated between the pulper and the thickener without wasting any waste. Compared to adding water and steam without circulation, the amount of water and steam added can be reduced by approximately 1 to 30%, and while the amount of chemicals consumed is the same, the concentration is approximately 9 to 5 times higher. It can be brought into contact with a piece of paper and absorbed into the paper evenly and quickly.

There is a rotationally driven agitator inside the lower end of the retention tower.While rotating, dilution water is jetted out from the front face in the same direction as the retention tower, and the swollen paper stock inside the lower end of the tower is sucked in from the back side of the agitator. It can be extracted with a pump through the hollow central shaft (this tower with an agitator can be used as described in Japanese Patent Publication No. 17-17-!;!!g3J proposed by the applicant of this patent), or the lower end of the tower. Extract it with a pump through the piping connected to the side.

The tower is a vertical tower with a large capacity, and the coarse paper stock with a density of ~30% is fed into the thickener from the top, and as mentioned above, the swollen material is successively sucked out from inside the bottom end. It takes over 10 hours to reach the bottom of the tower, during which time the large pieces of paper slowly descend inside the tower, becoming hydrated and swollen under the action of chemicals, turning into fibers, and becoming ink. Emulsification and bleaching of the fibers occur, and the bonding strength with plastic film pieces and metal foil pieces also weakens, and most of the film pieces and foil pieces separate from the paper pieces.

The optimal processing time for large pieces of paper fed into the retention tower to reach the bottom of the tower varies depending on the quality of the waste paper, but for example, in the case of high-quality plastic laminated waste paper, it is 2 to 30 hours, and depending on the paper quality, it is about 13 hours. The time may be longer than the effective time, for example, several hours, and the adjustment of this time can be determined by the height of the column and the amount of swollen material extracted from the bottom of the column.

From the bottom of the tower, a pump 6 extracts the swollen fibrous material together with coarse pieces of plastic and foil at a concentration of about 3%, and sends it to a vibrating screen 7. The diameter of the holes in the screen is 3 to 6 mm, and large pieces of plastic or foil cannot pass through these holes, so most of them are
Can be separated and removed.

After passing through the screen, the fibrous matter was removed by flotation separation of emulsified ink, oil, wax, pitch, etc. in a flotation separation device 8, and then sent to a secondary screen lθ with a pump to separate foreign matter again. After that, it is treated with a cyclone//washer 12 to obtain pulp.

According to the present invention, the pulper only crushes the laminated waste paper into coarse pieces that pass through holes with a diameter of 10-1/-osm in the strainer, so the residence time in the pulper is short and power consumption is low. Since the fibers that make up the paper strips are not mechanically damaged, high-quality recycled pulp can be produced, and because the plastic and metal foil laminate pieces are not broken down into small pieces and remain coarse in size, they can be used for retention towers. After ripening, it can be almost completely separated and removed using a screen.

[Brief explanation of drawings]

The drawing shows a flow sheet of an embodiment of the present invention, where l represents a pulper, da represents a retention tower, and 7 represents a screen. Special fraud applicant Masashi Kobayashi

Claims (1)

[Claims] Papermaking raw materials including laminated waste paper are crushed into coarse paper pieces that pass through the holes of the strainer using a pulper equipped with a strainer with a hole diameter of 10 to 10 m, and these coarse paper pieces are stored in a retention tower for at least 70 hours. Recycled pulp from papermaking raw material mixed with laminated waste paper, which is characterized in that the paper pieces are hydrated and swollen into a fiber state, the bond between the paper pieces and the laminate pieces is weakened, and then the laminate pieces are separated and removed using a screen with a hole diameter of 3 to 6 fins. Manufacturing method.