JPH0470436B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to fiber reinforced plastics (hereinafter referred to as
This paper relates to the manufacturing method of inorganic fiber sheets used as reinforcing materials for fiber reinforced ceramics (FRP), fiber reinforced ceramics (FRC), and fiber reinforced metals (FRM).

[Conventional technology]

Carbon fiber, boron fiber, SiC fiber, alumina fiber, and BN fiber are used as reinforcing materials for composite materials such as FRP, FRC, and FRM, but these are all unidirectionally reinforced composite materials using continuous fibers. Composite materials using continuous fiber cloth were the most common. However, with recent advances in gas phase reaction methods and liquid phase reaction methods, short fibers and whiskers of the above-mentioned inorganic fibers can be easily produced, and there are great expectations for them as reinforcing materials for composite materials.

Conventionally, as shown in JP-A-50-160565, when these inorganic short fibers and whiskers are used, they are mixed with plastics, ceramics, metals, etc. that serve as matrix materials for composite materials, and then pressurized. It is used by a method of thermoforming or a method of preforming inorganic fibers or whiskers into a molded object using a suitable binder and then impregnating the pores of the preform with a matrix material. In addition, when producing laminated molded products or thin-walled molded plates, a method is used in which inorganic fibers or whiskers are formed into a sheet, the sheet is impregnated or coated with a matrix material, and then laminated molded. Using these inorganic fibers and whiskers
In the manufacturing method of composite materials such as FRP, FRC, and FRM, the first method of mixing inorganic fibers and whiskers with the matrix material causes the inorganic fibers and whiskers to be damaged by shear force during mixing, resulting in the aspect ratio of the reinforcing material being The disadvantage is that it decreases.

In addition, this method has drawbacks such as the inability to mix a large amount of reinforcing material, so recently it has been
The reinforcing material preforming method shown in 2 and the lamination molding method in which the reinforcing material is formed into sheets are adopted. Both of these molding methods use plastic matrix material.
It is an effective method because it can be applied to both ceramics and metals.

[Problem that the invention seeks to solve]

The most convenient form of the reinforcing material used in the above-mentioned preforming method and lamination molding method is in the form of a sheet, and this sheet can be formed into various shapes or used as it is. It is said that it is difficult to manufacture sheets using short fibers with a fiber length of several millimeters or less or whiskers with a fiber length of several tens of microns to several hundred microns. Attempts have been made to form these fibers and whiskers into sheets using large amounts of binders, such as pulp, organic fibers, emulsions of synthetic resins, latexes of synthetic rubber, and polymer flocculants, either alone or in combination. The actual situation is that the amount of binder added is 20 to 30% by weight. Furthermore, a method for producing a continuous sheet with uniform fiber distribution and small thickness variations has not yet been established.

This invention was made to solve this problem, and with a small amount of binder, fibers with a fiber length of several millimeters or less to whisker-like fibers with a fiber length of several tens of microns to several hundred microns can be easily formed into fibers. The purpose of the present invention is to provide a method for manufacturing sheets of inorganic fibers that prevents damage to the fibers, allows for faster paper-making speed, and allows for continuous sheet production of inorganic fibers.

[Means for solving problems]

The inorganic fiber sheet manufacturing method of the present invention includes a step of draining a dispersion containing inorganic fibers as a main component and organic fibers fibrillated to a size of 1 micron or less as a binder, A sifter screen process in which the paper is made by a process of drying, a dehydration process in which the wet paper is pressed between a pair of press rolls to dehydrate it, and a drying process in which the dehydrated wet paper is dried by moving it in contact with a drying roll. In the dehydration step, a suction box is provided at least on one of the front and rear sides of the press roll, and an elastic body with a thickness of 2 mm or more is interposed between the pair of press rolls and the wet paper, and the press pressure is applied.
It dehydrates to less than 10 kg/cm.

[Effect]

By improving the dehydration process as described above, damage to the fibers can be prevented, and since the fibers are sufficiently dehydrated, drying becomes easier and paper making speed increases.

〔Example〕

Examples of inorganic fibers related to an embodiment of the present invention include glass fibers, carbon fibers, silicon carbide fibers, boron fibers, alumina fibers, alumina silicate fibers, quartz fibers, zirconia fibers,
Fibers such as asbestos fibers or whiskers of the above-mentioned fibers, and whiskers such as magnesia, boron carbide, boron nitride, silicon nitride, potassium titanate, graphite, etc. are used, but are not limited to these inorganic fibers. Any fibrous compound compound can be used. Note that "fiber" refers to fibers with a length of several millimeters or less, and "whiskers" refers to fibers with a length of several tens of microns to several hundred microns. Binders for these inorganic fibers include single fibers that have been fibrillated to a fiber diameter of 1 micron or less after removing impurities from natural fibers such as cotton, flax, wool, and silk, or cellulose and cellulose derivatives made from wood. Fibers made of viscose rayon or acetate fibers fibrillated to a size of 1 micron or less are used. In addition, polyamide fibers, polyvinyl alcohol fibers, polyvinylidene chloride fibers, polyvinyl chloride fibers,
After stretching polyacrylonitrile fibers, polyester fibers, polyethylene fibers, polypropylene fibers, polyurethane fibers, polycyanide vinylidene fibers, polyfluoroethylene fibers, etc. to near the limit, they are fibrillated using strong shearing force. Synthetic fibers can be used as binders. Furthermore, fibrillated heat-resistant organic fibers such as wholly aromatic polyamide fibers and phenol-formaldehyde fibers can also be used.

In addition, fibers other than those mentioned above can also be used if they are fibrillated to a single fiber diameter of 1 micron or less.
Either can be used. Further, it is preferable to use these binders in an amount of 1 to 15% by weight based on the above-mentioned inorganic fibers. The smaller the fiber diameter of these binders is compared to the fiber diameter of the inorganic fibers, the higher the bonding strength can be exhibited even when added in small amounts. Furthermore, the fiber length of the binder is preferably longer than the inorganic fibers, but is not particularly limited. Note that if the fiber diameter is 1 micron or more, the binding efficiency decreases, and if the fiber diameter is 1% by weight or less and 15% by weight or more, the binding force similarly decreases.

The drawing is a block diagram of a Fourdrinier paper machine according to an embodiment of the present invention, and in the drawing, 1a indicates a raw material dispersion;
1b is an inorganic fiber sheet, 2 is a saking blade, 3 is a dispersion mixing roll, 4 is a screen, 5 is a tension roll, 6 is a suction box, 7a is an under felt as an elastic body, 7b is an elastic body Top felt, 8 is a tension roll, 9 is a press roll, 10 is a canvas, 11 is a tension roll, 12 is a drying roll, 13 is a winding roll, 15 is a moving direction of the tension roll, 16 is a winding In the sheet, 17 is the rotation direction of the press roll, 18 is the winding rotation direction, and 19 is the rotation direction of the drying roll.

That is, first, a constant flow of the raw material dispersion liquid 1a was flowed into a flow box equipped with a saking blade 2 and a dispersion mixing roll 3, and the dispersion liquid that overflowed from the flow box was dehydrated using a sieve screen 4. paper. The dewatering method is carried out in a suction box set up at 6, and the dehydrated wet paper is further dehydrated at a press roll at 9, and the sheet is transferred to a drying process. In this outflow process, if a means for rotating and vibrating the dispersion consisting of a dispersion mixing roll (3) and a saking blade (2) is used in the flow box, these controls will prevent the inorganic fibers from settling and will also prevent the inorganic fibers from settling. This is preferable because it can be uniformly dispersed and overflowed to the screen portion, resulting in a homogeneous sheet. This mixes the dispersion liquid by causing a flow in the rotating direction at 3, and further gives vibration in a direction perpendicular to the flow direction of the dispersion liquid by 2 saking blades.

In addition, the dispersion liquid contains inorganic fibers as a main component and organic fibers fibrillated to a fiber diameter of 1 micron or less as a binder at a ratio of 1 to 15% by weight relative to the above inorganic fibers, and these are mixed with water, etc. It is preferable to use a material obtained by dispersing it in a dispersion medium at a concentration of 1 to 0.1% because a homogeneous sheet can be obtained.

Furthermore, in the screen netting process, it is preferable to make the suction force of the suction box 6 as large as possible. If the dehydration in the sieve process is insufficient, it will be difficult to move from the sieve process to the next process. Dewatering by press roll 9 in the dehydration process is 7
The under felt (a) and the top felt (7b) are placed between rolls for dehydration. At this time, in order to prevent the inorganic fibers from breaking due to the pressing pressure of the rolls, the linear pressure between the rolls must be 10 kg cm or less, and the felt thickness must be 2 mm or more. In addition, in the figure, a hard material such as metal is used as the roll material, and felt with a thickness of 2 mm or more is used as the elastic body, but if the roll material is made of soft rubber, for example, it can also be used as an elastic body itself. Function. Furthermore, in order to increase the dewatering efficiency in this area and increase the paper making speed, a suction box with a large suction force must be installed at least one of the front and rear sides of the roll. If the dehydration rate is poor, it is preferable to increase the installation distance of the suction box 6 and increase the suction force instead of increasing the linear pressure of the press roll. It is preferable to make the linear pressure of 9 as small as possible. The inorganic fiber sheet formed into a sheet and dehydrated in this manner passes through 12 drying rolls in the drying process, is dehydrated by more than 99%, and is wound up with 13 winding rolls. In this drying process, the diameter of the 12 drying rolls used is set as large as possible, and the drying rolls with a large heat capacity can dry the paper sufficiently, which increases the papermaking speed, which is preferable. A sealed jacket roll is suitable, and the heating method for the heating medium is preferably an induction heating method that can reduce energy loss and raise the temperature in a short time. type can also be used.

〔Effect of the invention〕

A process of flowing a dispersion containing inorganic fibers as a main component and organic fibers fibrillated to a size of 1 micron or less as a binder, a screen process in which the flowed dispersion is made into paper using a screen, and a pair of presses. A dehydration process in which the paper-made wet paper is dehydrated by pressing it between rolls, and a drying process in which the dehydrated wet paper is dried by moving it in contact with a drying roll are carried out, and the dehydration process is carried out by pressing the paper-made wet paper between rolls. By providing a suction box on at least one of the front and rear, interposing an elastic body of 2 mm or more in thickness between the pair of press rolls and the wet paper, and dehydrating the paper at a press pressure of 10 Kg cm or less,
An inorganic fiber sheet that uses a small amount of binder to easily prevent fiber breakage, even from fibers with a fiber length of a few millimeters to whiskers with a fiber length of tens of microns to hundreds of microns, and can be made into continuous sheets at a faster papermaking speed. A manufacturing method is obtained.

[Brief explanation of drawings]

The drawing is a block diagram of a Fourdrinier paper machine according to an embodiment of the present invention. In the figure, 1a is a raw material dispersion, 1b is an inorganic fiber sheet, 4 is a screen, 7a and 7b are elastic bodies, 9 is a press roll, 12 is a drying roll, 13
is the take-up roll.

Claims (1)

[Claims] 1. A dispersion step in which a dispersion containing inorganic fibers as a main component and organic fibers fibrillated to a size of 1 micron or less as a binder is discharged, and the discharged dispersion is used to make paper using a slotted screen. In the above-mentioned method, which performs a screen screening process, a dehydration process in which paper-made wet paper is dehydrated by pressing it between a pair of press rolls, and a drying process in which the dehydrated wet paper is dried by moving it in contact with a drying roll. In the dewatering process, a suction box is provided on at least one of the front and rear sides of the press rolls, an elastic body with a thickness of 2 mm or more is interposed between the pair of press rolls and the wet paper, and the press pressure is set to 10 kg cm or less. A method for manufacturing sheets of inorganic fibers. 2 Claim 1 in which the elastic body is felt
A method for producing a sheet of inorganic fibers as described in Section 1. 3. The method for manufacturing an inorganic fiber sheet according to claim 1, wherein the elastic body is a soft rubber. 4. The drying step is carried out using a drying roll having a diameter of 300 mm or more and having the largest heat capacity.
A method for manufacturing an inorganic fiber sheet according to any one of items 1 to 3. 5. The method for manufacturing an inorganic fiber sheet according to any one of claims 1 to 4, wherein the drying roll is an induction heating jacket roll. 6. The step of flowing out is the method according to any one of claims 1 to 5, in which the dispersion liquid is flowed out while preventing sedimentation of the inorganic fibers by using means for rotating and vibrating the dispersion liquid. Inorganic fiber sheet manufacturing method. 7 The dispersion liquid contains inorganic fibers as the main component and organic fibers fibrillated to a fiber diameter of 1 micron or less as a binder in a ratio of 1 to the above inorganic fibers.
7. The method for producing a sheet of inorganic fibers according to any one of claims 1 to 6, wherein the inorganic fibers are dispersed in water in a proportion of 15% by weight.