JPH09170199A - Sheet having continuous gradient function in thickness direction and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gradient function sheet suitable as a density-gradient filter by using plural kinds of raw materials and continuously varying the raw material composition in the thickness of the sheet. SOLUTION: A stationary wire part 17 is constantly and continuously supplied with fresh water, the lower part of the wire is constantly drained and the water- level is constantly maintained to a definite level at the upper part of the wire 17. Two kinds of paper materials 3, 4 held in containers 1, 2 are supplied to the sheet machine by opening valves 5, 6. Exclusively the paper material 3 is supplied to the sheet machine 12 at first and the ratio of the paper material 4 is continuously increased according to the lowering of the water levels in the containers 1, 2 since the paper material 4 is transferred to the container 1 and mixed by the stirrer 7. After the complete supply of the paper materials 3, 4 to the sheet machine 12, the sheet is dehydrated, the wet paper is peeled off from the wire 17 and dried with a drier under pressure to obtain the objective gradient function sheet having raw material composition continuously varying in the thickness direction of the sheet.

Description

Detailed Description of the Invention

[0001]

[Industrial application] A functionally graded sheet made of two or more kinds of raw materials, in which the composition of the raw materials continuously changes in the thickness direction of the sheet, a method for producing this sheet, and the production of this sheet. Regarding the device.

[0002]

2. Description of the Related Art Conventionally, as a sheet whose composition changes in the thickness direction, a plurality of layers having different fiber densities are disclosed, for example, as disclosed in JP-A-62-33514 and JP-A-64-43324. There was a sheet that was characterized by. Also, as a method for manufacturing a sheet at a laboratory level, the composition of which varies in the thickness direction of the sheet, Japanese Patent Publication No. 63-4899.
8 discloses a method and an apparatus for manufacturing a multilayer sheet.

[0003]

Problems to be Solved by the Invention In all conventional sheets, the composition of which changes in the thickness direction, the composition changes in each layer. It's not. In addition, Japanese Patent Publication No. 63-4899
The sheet machine disclosed in No. 8 is designed for multi-layer papermaking, and is not equipped with a device for continuously changing the blending ratio of the stock material to be supplied. It is possible.

In the present invention, the existing sheet machine is improved, and while continuously dehydrating under the wire of the sheet machine, the sheet machine is continuously supplied with different raw materials, so that the sheet thickness can be improved. Provided is a functionally gradient sheet in which the composition of raw materials continuously changes in the vertical direction.

[0005]

In order to manufacture a functionally graded sheet in which the raw material composition continuously changes in the thickness direction of the sheet according to the present invention, an existing sheet machine for a paper machine at a laboratory level is improved. Then, the manufacturing apparatus of the functionally gradient sheet shown in FIG. 1 was devised.

The manufacturing is performed as follows. First, fresh water is always continuously supplied to the wire portion in a stationary state, dehydration is always performed at the lower portion of the wire, and the water level is always kept constant at the upper portion of the wire. Next, the paper materials 1 and 2 are put into the containers 1 and 2 and kept at the same water level. After that, the stoppers 1 and 2 are opened to supply the paper material to the sheet machine. Initially, only the stock 1 is sent to the sheet machine, but as the water levels in both containers drop, the stock 2 moves to the container 1 and is mixed with the stock 1 by the stirrer 1, so the raw materials supplied to the sheet machine Is continuously changed to the one in which the ratio of the stock 2 is increased.
In the sheet machine, the paper material is mixed with fresh water, and is further uniformly dispersed in the fresh water by a stirring device. The dispersed paper material is rectified by two types of plates, then moved to the wire portion and dehydrated, and the raw materials are laminated on the wire while continuously changing the composition. After the supply of all the stock has been completed, the supply of fresh water is stopped, and after dehydration, the wet paper formed by a conventional method is stripped from the wire and pressed and dried with a dryer to obtain a functionally gradient sheet.

The apparatus for supplying the paper material to the sheet machine is not limited to the apparatus shown in FIG. 1, and is not particularly limited as long as it can supply two or more kinds of paper material to the sheet machine while continuously changing the mixing ratio. For example, as shown in FIG. 2, a device may be used in which a pump is installed in each container and the feed rate of both pumps is continuously controlled to change the mixing ratio.

The wire used in the present invention may be any wire used in the production of ordinary paper and wet non-woven fabric,
Any of wire mesh made of copper or stainless steel, plastic wire made of polyester or nylon, or the like can be used. The size of the wire mesh may be from about 50 mesh to about 250 mesh.

The raw material used in the present invention is not particularly limited as long as it is a raw material used in the production of paper and wet non-woven fabric. Wood fibers such as softwood pulp and hardwood pulp,
Non-wood fibers such as mulberry, san tsubaki, goose bark, Manila hemp, linter
Chemistry of rayon fiber, polyester fiber, acrylic fiber, polyolefin fiber, polyvinyl alcohol fiber, etc.
Inorganic / metal fibers such as synthetic fibers, carbon fibers, glass fibers, stainless fibers, and alumina fibers, or heat resistance, water absorption, oil absorption, water resistance, water repellency, conductivity,
Any fiber such as a functional fiber provided with a special function such as chromic property or electret property can be used.

Further, the raw material is not limited to the fiber, and any of fillers, dyes, functional inorganic powders, functional organic materials and the like can be used as long as they are added to ordinary paper and wet non-woven fabric.

The raw materials to be combined are not limited to two kinds but may be three kinds or more. In that case, it can be produced by using one or both of the paper materials mixed with several kinds of raw materials.

The functionally gradient sheet according to the present invention is one in which the fiber composition, fiber density, functionality and the like are continuously changed from the front surface to the back surface of the sheet. It is fundamentally different from conventional, multi-layered sheets.

The sheet in which the composition of the fibers is continuously inclined from the front to the back is produced by combining different kinds of fibers such as a combination of softwood pulp and rayon fibers, a combination of polyester fibers and polyolefin fibers, a combination of alumina fibers and stainless fibers. It is a sheet in which the fiber composition from the front surface to the back surface of the sheet continuously changes in the thickness direction.

The sheet in which the fiber densities are continuously inclined from the front to the back is, for example, a combination of 0.7 denier rayon fiber and 3 denier rayon fiber, a combination of 0.2 denier ultrafine polyester fiber and 3 denier rayon fiber. As described above, the sheet is manufactured by using fibers having different fiber diameters, and the fiber density from the front surface to the back surface of the sheet continuously changes in the thickness direction.
Not only the same kind of fibers but also different kinds of combinations can be produced by combining raw materials having different diameters. The diameter of the fiber to be used is not particularly limited, and is usually a fiber having an average diameter of about 1 μm to about 40 μm, as long as it is a fiber used in the production of ordinary paper and wet non-woven fabric. is not.

The sheet in which the functions of the front and back surfaces of the fibers are continuously inclined combines several kinds of fibers having the functions of heat resistance, water absorption, oil absorption, water resistance, water repellency, conductivity, chromic property, electret property, etc. A sheet manufactured by the above method, and these functions continuously change in the thickness direction from the front surface to the back surface of the sheet. The function of inclining is not limited to the case of utilizing the special function given to the fiber, but may be the case of utilizing the function originally possessed by the fiber. Also,
The functional powder may be adsorbed on the fiber to utilize its function, or the powder itself may be used as the raw material.

The thickness of the functionally graded sheet is not particularly limited and can be freely set from about 20 μm to about 5,000 μm. US basis weight which may in any case from those of 10 g / ^{m 2} up of about 2,000 g / ^{m 2.}

[0017]

EXAMPLES The measurement and evaluation in the examples of the present invention are as follows. The basis weight of the rice is measured by the metric basis weight of JIS-P-8118 paper, and the thickness is measured by the thickness and density of JIS-P-8118 paper and paperboard. The evaluation of the change in the fiber composition in the thickness direction of the sheet was performed by dividing the sheet micrograph and the electron micrograph into 5 sections from one surface,
This was done by image analysis of each section. For image analysis, image folding device S manufactured by Olympus Optical Co., Ltd.
It was carried out by a method of evaluating the area of an image obtained by binarizing a cross-sectional photograph using P500.

Example 1 As a raw material, 4 liters of chemical softwood pulp was adjusted to a stock concentration of 0.06% to prepare a stock 1, and a diameter of 7 μm,
Carbon fiber having a length of 13 mm was adjusted to 4 liters so as to have a stock concentration of 0.06%, which was used as a stock 2, and 1 d-3 mm of polyvinyl alcohol fiber (10% as a raw material) was used as a binder for both stocks. Was added to. The stock 1 and the stock 2 are supplied to the apparatus of FIG. 1 by the method described in 0006, and the blending ratio of carbon fiber and softwood chemical pulp continuously changes in the thickness direction of the sheet.
A prototype of a functionally graded sheet having m ² and a thickness of 1,210 μm was produced.

Regarding a micrograph of a cross section of this sheet,
The analysis results of the fiber composition obtained by binarizing the pulp fiber portion and the carbon fiber portion using an image analyzer and dividing the pulp surface into 5 sections in the thickness direction and measuring the area ratio are shown. Shown in 1.

[0020]

[Table 1]

Example 2 4 l of a raw material having a polyester / nylon ultrafine composite fiber of 0.2d-5 mm and a stock concentration of 0.07% was prepared and used as a stock 1, and 3d-5 mm rayon fiber was prepared. 4 liters of stock with a stock density of 0.07% were prepared and used as stock 2, and 1d-3m as a binder.
m polyvinyl alcohol fiber (10% of raw material) was added to both stocks. These paper materials are supplied to the sheet machine shown in FIG. 1 by the method described in 0006, and the ultrafine composite fibers and rayon fibers are continuously changed in the thickness direction of the sheet to continuously change the size of voids. U.S. basis weight 289g
/ M ² and a functionally graded sheet with a thickness of 890 μm were prototyped.

A scanning micrograph of the cross section of this sheet was binarized into fibers and voids using an image folding device, and the average cross-sectional area of the voids was divided into 5 sections every 150 μm in the thickness direction from the dense surface. Table 2 shows the results of the analysis.

[0023]

[Table 2]

[0024]

EFFECTS OF THE INVENTION It is possible to manufacture a functionally graded sheet in which the fiber composition, fiber density, functionality and the like are continuously changed in the thickness direction of the sheet. In addition, functionally graded sheets do not have the problem of delamination compared to sheets with a multi-layer structure manufactured by laminating and pasting, and since they have continuous inclination, thin sheets can also be manufactured. .

A functionally graded sheet in which the fiber density continuously changes in the thickness direction of a sheet produced by combining a thick fiber diameter and a thin fiber diameter, the void diameter also continuously changes, and as a density gradient type filter. Available. In this case, since a small substance to a large substance can be efficiently collected according to the size of the voids, the pressure loss can be suppressed low and the filter life can be improved. This is one of the most effective applications of functionally graded sheets.

[Brief description of the drawings]

FIG. 1 is a schematic view of a sheet manufacturing apparatus having a tilt function in the thickness direction.

FIG. 2 is a schematic diagram of an example of a stock material supply system of a sheet manufacturing apparatus having a tilt function in the thickness direction.

[Explanation of symbols]

 1 Container 1 2 Container 2 3 Paper Material 1 4 Paper Material 2 5 Stopper 1 6 Stopper 2 7 Stirrer 1 8 Starter 2 9 Piping 10 Stirrer 11 Fresh Water 12 Sheet Machine 13 Stirrer Container 14 Shape of Stirrer Container Bottom 15 Plate 1 16 Plate 2 17 Wire 18 Tube Pump with Inverter 1 19 Tube Pump with Inverter 2

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsuhiro Fujiwara 2 Ehime Prefectural Paper Mill at 281 Hirotsubo, Kawanoe Town, Kawanoe City, Ehime Prefecture

Claims (2)

[Claims] 1. A functionally graded sheet material, which is made of two or more kinds of raw materials and in which the composition of the raw materials continuously changes in the thickness direction of the sheet. 2. The method for producing a functionally graded sheet and the apparatus therefor according to claim 1, wherein a stock material having a raw material composition continuously changed is supplied to a wire that is continuously dehydrated.