JPS63227897A - Production of whisker sheet - 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 [Industrial Application Field] The present invention provides a whisker sheath kI7'11 which has whiskers homogeneously dispersed, has high strength and flexibility, and is easy to handle.
III [Conventional technology] Whiskers have extremely high mechanical strength and elastic modulus, and also have excellent chemical and thermal stability.
It is attracting attention for a wide range of applications including reinforcing materials for composite materials. If this whisker can be made into a sheet, F
This not only facilitates the production of composite reinforcing materials such as RM, FRC, or FRP, but is also extremely useful in the electric and electronic industries as a matrix for IC substrates and phosphoric acid fuel cells.

however. Whiskers have a diameter of 0.1 to 5 μm and a length of 1
It is a fine fibrous substance with a volume of 0 to 500 μl, and it is difficult to form a sheet using only whiskers. Moreover, even if it is made into a sheet, it cannot provide enough mechanical strength to handle it.

There is also a method of mixing fibrous substances with whiskers and integrally molding them using a papermaking method, but whiskers with fine shapes are difficult to be captured by fibrous substances. It is difficult to obtain a sheet in which whiskers are homogeneously dispersed at a high concentration. For example, when formed into a sheet, the dispersion of whiskers tends to be different between the front and back sides.

[Problem that the invention seeks to solve]

The present invention solves the above problems. The present invention provides a method for manufacturing a whisker sheet that has high strength and flexibility, and is easy to handle, in which whiskers are homogeneously dispersed.

[Means for solving problems]

In other words, the present invention... 100 parts by weight of whiskers and 40 to 100 parts by weight of fluorine-based resin that can be made into fibers! A kneading aid is added to one part and kneaded, and the kneading aid is dissolved and removed from the kneaded product using a solvent, then redispersed in an organic solvent, filtered and dried, and heated to a temperature of 330°C.
This is a method for producing a whisker sheet, characterized by hot-press molding at ~400°C and a pressure of 10~150 kg/Cx''.

As the whiskers, ceramic whiskers such as SiC and 5isN4 are preferably used. The fiberizable fluorine-based resin used in the present invention refers to a powder resin containing a fluorine component that can be fiberized into a spider web shape by applying shearing force. Ceramic whiskers and a fluorine-based resin that can be made into fibers are mixed and vigorously kneaded using a kneading machine such as a roll or a Ni-Goo. The mixture is subjected to strong shearing force, and the fluororesin fibers form, forming a spider web-like network. Ceramic whiskers stably exist while being homogeneously dispersed and captured and immobilized in the web that forms.

In this case, it is desirable to add a kneading aid such as an epoxy resin or glycerin in order to easily and thoroughly knead the ceramic whiskers and the fluorine-based resin.

The amount of fluorine-based resin that can be made into fibers is determined from the viewpoint of increasing the strength characteristics of the sheet and maintaining the porosity of the sheet. The ratio is set to 40 to 100 parts by weight per 100 parts by weight of whiskers. If it is less than 40 parts by weight, the mechanical strength will not be sufficient and it will be difficult to homogeneously disperse the whiskers.

If it exceeds 100 parts by weight. This is because not only the unique performance of whiskers is reduced, but also the porosity is reduced.

The kneaded product is placed in a suitable solvent such as a suitable solvent or water, stirred and mixed, and the kneading aid is dissolved and subjected to over-separation. It is necessary to repeat this operation several times to completely remove the kneading aid. Next, the filter cake is dispersed in an organic solvent such as alcohol, acetone, benzene, toluene, xylene, ether, etc., stirred, filtered and dried to form a homogeneous structure in which whiskers are dispersed and fixed in the fibrous fluororesin. to obtain a mixture of In this case, a predetermined amount is used in consideration of the shape and thickness of the sheet, but the dispersion concentration in the organic solvent is preferably adjusted to 0.1 to 5 wt%.

This mixture is placed in a mold and hot-pressed. During hot press molding, the temperature is set at 330 to 400°C.

This is to melt the fluorine-based resin particles connected in a fibrous form to form fibers, and to fuse the resin components forming a spider web-like network to each other to firmly connect them.

That is, it is necessary to heat it to 330° C. or higher, which is the melting temperature of the fluorine resin. On the other hand, if the temperature exceeds 400°C, the fluororesin component will begin to decompose, so the heat treatment must be carried out at a temperature of 400°C or lower. For pressure treatment, a metal plate with a smooth surface such as stainless steel or iron is used as a pressure plate.
Molding is carried out under a pressure of 10 to 150 kg/cm''. By this hot-pressing process, whiskers are homogeneously dispersed, and a sheet with a thickness of 0.1 to 2x* with high mechanical strength can be produced.

[For production]

According to the present invention, whiskers are uniformly dispersed and captured in the spider web-like network structure of fluororesin fibers formed by strong shearing force at the time of crosstalk. Next, this is heat-press molded to complete the fiberization of the fluorine-based resin, and the fiberized resins are fused and bonded to each other, thereby improving the strength of the sheet and obtaining a whisker sheet with even greater flexibility. be able to.

〔Example〕

Example 1 SiC with a diameter of 0.2 to 0.5μ11 and a length of 30 to 60μ
To 100 parts by weight of the whiskers, 50 parts by weight of a fluorine-based resin (Teflon K, manufactured by DuPont Mitsui Fluorochemical Co., Ltd.) which can be made into fibers is added, along with 1000 parts by weight of an epoxy resin (Epicoat 828, manufactured by Yuka Shell Epoxy Co., Ltd.) as a kneading aid. The mixture was kneaded using three rolls. The kneaded material was put into 1500 parts by weight of acetone, stirred and mixed to dissolve the epoxy resin, and then separated by filtration. This operation was repeated three times to completely remove the epoxy resin. Next, the filtrate was dispersed in ethanol at a concentration of 1 wt%, and then over-dried using a 500 mesh nylon screen.

It was removed from the screen, placed in a 700xx square mold, sandwiched between stainless steel plates with smooth surfaces, and heat-treated at 350°C for 1 hour while being pressurized with a pressure of 100 kg/cx''.The obtained whisker sheet was 687y angle, thickness 0.15
IjI, and the tensile strength was 6.0 kg/cm''. Also, its properties were flexible and easy to handle.The porosity was 70%, and the weight was l
It was 25゛9/x''.

This whisker sheet is 10x13 wide! , length 500J
lff, the tip 10+u was immersed in a 95% phosphoric acid aqueous solution, and the phosphoric acid permeation rate was measured.
z/min.

Example 2 500 parts by weight of glycerin was added as a kneading aid to 100 parts by weight of the same SIC whiskers as in Example 1 and 90 parts by weight of a fibrousable fluororesin, and the mixture was kneaded using three rolls, and then 1500 parts by weight of water was used. The glycerin was separated into a melting furnace. After repeating the operation of dissolving and removing glycerin three times, the particles were dispersed in ethanol at concentrations of 0 and 5 vt%, and hot-press molded in the same manner as in Example 1. However, the pressure is 50kg/
cm", and the temperature was set at 360°C. The obtained whisker sheet had a square size of 680zx, a thickness of 0.18xm, a tensile strength of 10.6 kg/cx", a porosity of 66%, and a weight of 182.
97x''.The phosphoric acid permeation rate was 17xx1
It was a minute.

Comparative Example A whisker sheet was prepared in the same manner as in Example 1, except that 20 parts by weight of a non-fibrous fluororesin was mixed with 100 parts by weight of SIC whiskers.

The resulting sheet is 693xx square, 0.17mm thick and 11mm thick.
The porosity was 80% and the weight was 8997x''.The tensile strength was as low as 1.0 kg/cm'', and its properties were poor in flexibility. Although it was immersed in a phosphoric acid aqueous solution, it was not possible to measure the permeation rate because it was brittle.

〔Effect of the invention〕

According to the present invention, it is possible to easily obtain a whisker sheet that uses fluororesin fibers as a skeleton, whiskers are highly homogeneously dispersed, and has high mechanical strength. Moreover, it is flexible and easy to handle, so it can be used for composite materials and other materials.
It is extremely useful as a base material for various industrial materials such as carbon substrates and phosphoric acid fuel cell matrices.

Claims (2)

[Claims] 1. A kneading aid is added and kneaded to 100 parts by weight of whiskers and 40 to 100 parts by weight of a fibrousable fluororesin, and the kneading aid is dissolved and removed from the kneaded product using a solvent, and then redispersed in an organic solvent and filtered. A method for producing a whisker sheet, which comprises, after drying, hot-pressing molding at a temperature of 330 to 400°C and a pressure of 10 to 150 kg/cm^2. 2. The method for manufacturing a whisker sheet according to claim 1, wherein the whiskers are SiC or Si_3N_4 whiskers.