JPS60134100A - Production of inorganic fiber sheet 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 present invention relates to a method for producing an inorganic fiber sheet material useful as a high-performance filter material. More specifically, it relates to a method for producing an inorganic fiber sheet material, which is characterized by using microfibrillated cellulose (hereinafter abbreviated as MFc) as a fixing agent and dispersant for inorganic fibers, and producing a slurry containing the microfibrillated cellulose. be.

Conventionally, asbestos has been used as a filtration material for removal of fine dust in the air and precision of liquids, and has been used as a filtration material for J1 applications, and asbestos has been used as a material for its high trapping performance and low filtration resistance. Because of the above problems, its use is considered undesirable.Therefore, the development of an alternative is desired.

In order to produce a filtration material with high capture performance and low filtration resistance, it is necessary to use a rigid fibrous material with as little glue as possible. Therefore, materials commonly referred to as inorganic fibers are used for that purpose.

The inorganic fibers mentioned here include glass fiber, ceramic fiber, rock wool, slag wool, alumina fiber, PM-
F' (a type of rock wool), alkali metal titanate, silicon carbide, silicon nitride, carbon fiber, etc. Some of these are naturally produced in the form of fibers, and fibers can be produced by means such as melt spinning. Some are formed into shapes.

Among them, glass fiber is particularly useful as a material for inorganic sheet materials because the technology for producing fine and uniform fibers from raw materials of constant quality and purity has been established. however,
Since its surface is smooth and its dispersibility and fixing properties are poor, it is difficult to make paper by itself.

The inventors have discovered that microfibrillated cellulose (MFC)
) acts as a good fixing agent and dispersant for inorganic fibers, and it has been discovered that inorganic fiber sheets can be efficiently produced using MFC, and the present invention has been achieved.

MFC is obtained by beating the cellulose solids into a viscous form in water using the method shown in the specification of No. 1980-1.00801, such as bulbs and linters. It is defined as ``fibrous cellulose''.

MFC consists of finely divided cellulose fibers with a diameter of several μW.
It is an aggregate of many fibrils as shown below.

The length of fibrils varies somewhat depending on the raw material and manufacturing conditions, but those obtained from wood pulp are on the order of several hundred μm. MFC has a water retention capacity about 6 times that of the raw material valve, and when dispersed in water at a concentration of cellulose solid content of 0.4% or more, it forms a stable suspension. When this suspension is cast and dried, a translucent film is obtained.

Although inorganic fibers, especially glass fibers, have poor solid dispersibility, they are well dispersed when mixed with an MFC suspension by stirring. In addition, the smaller the diameter or the longer the length of inorganic fibers, the more difficult it becomes to fix them, and they may be washed away during sheet formation or fall off even after sheet formation.
Using MFC improves fixing, resulting in a sheet with a high inorganic fiber sheath. The fixation and dispersion function of MFC on inorganic fibers is thought to be due to the entanglement of its fine fibrils.

When the inorganic fibers used contain long fibers, MFC can be used to form a sheet with high strength. In this case, the fiber diameter does not have much influence on the sheet strength. If only inorganic fibers with short fiber lengths, for example, 100 μm or less, are used, the resulting sheet material will only have low strength. In such cases, it is preferable to add other long fibers for the purpose of reinforcing the sheet strength. However, if the fiber length is too long, workability during papermaking will deteriorate, so it should be 500 μm to 5000 μm.
A value of about m is appropriate.

In this case, there is no particular restriction on the material of the relatively long fibers to be added;
In addition to vegetable fibers, synthetic fibers such as polyester, polyamide, and polypropylene, and regenerated cellulose fibers, alumina and glass fibers can also be used.

Conventionally, cationic starch, polyacrylamide, polyacrylic acid hydrazide, etc. have been known as substances that have a fixing effect on glass fibers, etc., but sheets made using these materials are prone to re-elution when used in aqueous fluid treatment. Therefore, there is a problem that it cannot be used for food applications, for example.

MFC, on the other hand, is inherently insoluble in water,
There are no ambidextrous problems at all. When MFC is used, even fine inorganic fibers can be formed into a sheet with a high fixation rate (high yield). The more MFC is used for inorganic fibers, the better the yield will be, but since the water speed during paper making is slow and the working time is longer, MFC/inorganic fibers = 20/8.
Approximately 0 is suitable. In addition, since MFC has a large fixing ability, it is possible to form a sheet even at 2/98 in the case of glass fiber. Even when fibers are added to increase sheet strength, it is possible to produce a sheet material in which the inorganic fibers account for 50% by weight or more of the total solid content. That is, the present invention relates to a method for producing an inorganic paper sheet, which is characterized in that the paper is produced using a slurry containing inorganic fibers and MFC as essential components.

In addition, in the manufacturing method of the present invention, it is also possible to appropriately use additives other than the essential components in combination within the range where the object of the present invention is achieved.

The inorganic fiber sheet 1 material obtained by the method of the present invention is
In addition to filtering material, it can be used as a base material for impregnation, separators, beaker cones, printed circuit boards, etc.

The present invention will be explained below with reference to Examples.

Example 1 Glass fiber (manufactured by Asahi Fiberglass, diameter 1°/lf'n
, length 3) 70 parts by weight, wood valve (Mitsubishi Paper L-
BKP) 30 parts by weight of 2% solids water suspension of MFC 50
parts by weight and 5,000 parts by weight of water were mixed and stirred to form a slurry, which was prepared using a TAPPI standard type hand paper machine (brass wire s0m).
The paper was made using esh). The obtained sheet was rotated at 150°
A sheet material having a thickness of 0.471 m and a basis weight of]2ag7z was obtained.

The following items were measured for the sheet material.

・Glass fiber retention rate Calculated from the weight of the sheet material (%) ・Rear length Calculated from the following formula ・Water absorption Stand the sheet material vertically, soak the bottom end in water, and water will rise through the sheet material in 10 minutes. Height: mm) Comparative Example 1 The procedure was the same as in Example 1 except that 1 part by weight of cationized polyacrylamide (Polystron 705, manufactured by Kabushiki Kagaku) was used in place of the MFC suspension in Example 1. A sheet material with approximately the same appearance, military songs, etc. as the sheet material of Example t was used! t
Ta.

Comparative Example 2 The procedure was the same as in Example 1 except that cationized hard powder was used in place of the MTi'C suspension in Example 1, and the sheet material, appearance, and mold needles of Example 1 were etc. obtained approximately the same sheet thickness.

Comparative Example 3 A sheet material was obtained by carrying out the same procedure as in Example except without adding the MFC suspension of Example J. The thickness of the sheet material is 0.3
mm, tsubo M], 05g/2.

Example 2 Fibrous potassium titanate (manufactured by Otsuka Chemicals, fiber length 20-3
011rn, fiber diameter 0.1-0.37z m) 100
Linter 12 with weight part, average fiber length 1.0'In1n
5 wt % water suspension/100 parts by weight, 250 parts by weight of 2 wt % water suspension of MFC and 4000 parts by weight of water are mixed;
A homogeneous slurry was prepared.

This slurry was made into paper according to the method of Example 1 and dried. Thickness of the obtained sheet material: O, 47 meters, H tsubo 1.1
It was 45 g/m.

Comparative Example 4 10% alumina sol instead of Example 20 MFC suspension
A sheet material was produced in the same manner as in Example 2 except that 50 parts by weight of the water suspension was used. (The thickness of the smoothed sheet material was 0.3 mm, and the basis weight was 5 g/ny.

Table 1 summarizes the number of measurements made for the sheet materials obtained in Examples and Comparative Examples.

Table 1 Examples], ! 18 05ji 8 G comparative example]
85 (1,5++ 51itt '2 !11f1.
51 77 // 3 +::〼il, 4 n (+8 Example 2 4+ 1 - - - Comparative example 4 42 - - Patent 11 rower 1 person Daicel Chemical Co., Ltd.

Claims (3)

[Claims] (1) A method for producing an inorganic fiber sheet material, which is characterized in that papermaking is performed using a slurry containing inorganic fibers and microfibrillated cellulose as essential components. (2) The method for producing an inorganic fiber sheet material according to claim 1, wherein the inorganic fiber is glass fiber. (3) The inorganic fiber content in the solid content of the slurry is 50
The method for producing an inorganic fiber sheet material according to claim 1 or 2, wherein the inorganic fiber sheet material is 98X.