JPS61127680A - Manufacture 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 (1) Technical field of the invention The present invention is directed to forming fine fibrous crystals, so-called whiskers, into one piece in a single layer or multilayer form by simple aqueous papermaking. This invention relates to providing a sheet whose properties are not impaired.

(B) Conventional whiskers are expected to have excellent chemical resistance, heat resistance, and stable chemical properties, as well as excellent mechanical properties such as tensile strength and elastic modulus, so they can be used to strengthen various composite materials. It is well known that early industrialization is expected for use in wood and heat-resistant materials.

When whiskers are used as reinforcing materials in various composite materials, their reinforcing properties can only be utilized if they are uniformly dispersed in the matrix, but this uniform dispersion is not easy. Therefore, if a sheet made of uniformly dispersed whiskers is obtained, it becomes possible to easily form a composite material using it.

However, such whiskers are extremely small in shape, for example, silicon nitride or silicon carbide whiskers have a fiber diameter of 0.
．． Because the whiskers are extremely fine, less than 5 μm in length and less than 300 μm in length, it is difficult to make a sheet with just the whiskers, and even after being made into a Yoshiba molded sheet, the sheet itself has no mechanical strength due to its handling, so it is difficult to put it into practical use. is difficult to offer. Furthermore, whiskers are not only extremely small in size compared to fine glass or carbon fibers, but also have extremely low dispersion ability, so it is difficult to form them into a sheet evenly. Previously, for example, such sheets were made by mixing whiskers made of silicon carbide or silicon titanide with an organic solvent such as acetone, as shown in Japanese Patent Publication No. 58-502193, etc., and then spreading the mixture thinly on aluminum foil. You can see an example of it being applied, dried, and integrated, but the whiskers simply adhere to the aluminum foil.
Due to the lack of holding capacity of the sheet itself and its workability, it has not yet been possible to form a practical sheet.

Separately from this, it is also possible to form a sheet by adding a conventional binder, such as a water-soluble resin, but such a method alone is unsatisfactory.

Therefore, it is desirable to preferably form these whiskers into sheets in order to make the material more versatile.

(C) Purpose of the Invention The purpose of the present invention is to provide a single layer or laminated whisker sheet that is easy to handle, can embody the attributes of whiskers at high yield and low cost, and can have any thickness and density. It is in. Other objects of the invention will become apparent from the description below.

(D) Structure of the Invention The object of the present invention is achieved by a method for producing a mixed paper, in which an aqueous composition comprising whiskers and a fibrous material having a freeness of 100 csf or less is integrally formed into paper.

That is, the idea is to add a natural or synthetic fibrous material to the whiskers and obtain a sheet by a normal papermaking method. child\
The fibrous material used in this process is required to have a good shape and properties in order to function as a whisker holding material, and in order to form a uniform sheet, the Canadian Standard Freeness (CSF) must be 100.
Use less than fibrous material. The fibrous material satisfies the above numerical values and is not particularly limited in shape, regardless of whether it is natural or synthetic. Further, the amount of the fibrous material to be combined can be arbitrarily selected depending on the degree of porosity or densification of the desired sheet, but from the viewpoint of sheet forming ability, less than 20 parts per 100 parts of whisker is sufficient. A value of 5 to 10% is preferable, and sufficient handling characteristics can be achieved in order to embody the attributes of whiskers. The gist of the present invention is to combine as fine a fibrous material as possible, that is, low sawa suisan, with whiskers, in order to achieve more preferable compatibility with the whiskers. It has a small surface area and lacks the ability to promote fine whiskers on its surface, resulting in no dispersion ability, making it difficult to form a desired sheet. Therefore, in order to enhance the ability of the whiskers to promote movement, it is necessary to reduce the P value to 100 or less. Furthermore, during papermaking, a well-known retention agent can be used in combination so that fine whiskers can be easily peeled off from the wire during papermaking.

The term "whiskers" as used in the present invention does not include the aforementioned silicon dioxide and silicon carbide alumina, but also substantially inorganic powders. On the other hand, fibrous materials include natural fibers such as cellulose fibers, regenerated cellulose fibers, and cellulose acetate, fibers made of aromatic polyamide, fibers made of nitrogen-containing polyheterocyclic compounds, and fibers made of polyphenylene oxide (polyarylene). ), aromatic, aliphatic polyester, etc. -5-
, making it possible to use them together.

A preferred embodiment of the present invention is a combination with a fibrous material having high thermal conductivity and heat resistance. For example, an aromatic polyamide fibrous material can be used as a printed circuit board or various industrial materials by using any sheet obtained from the fibrous material. This is advantageous in that it allows for the application of

In such a preferred embodiment, Japanese Patent Publication No. 37-573
A good bonding force can be achieved by mixing the aromatic polyamide fibrous material (fibrid) disclosed in No. 2, etc. with whiskers at the above-mentioned compounding ratio and heating or heating the mixture at the edges of the paper, near the softening point of the fibrous material. This is an excellent method because it increases the mechanical strength of the sheet. In this way, whiskers and fibrous materials can be made into a single sheet or a laminate (so-called gold dust).
After dispersing both at the same time or separately, they are dispersed in a wet state in a single layer or laminated. However, when dispersing before papermaking, the entanglement between the whiskers is strong and it is difficult to disperse, so it is difficult to disperse them uniformly. It is a method of adding fibrous material to a place where sufficient dispersion is achieved through means such as high-speed stirring with a dispersion medium such as glass or sand.
-6- to obtain a desired dispersion.

These whisker sheets of the present invention may be made using a conventional paper making method, such as a Fourdrinier paper machine, a circular paper machine, or a combination machine combining these machines, and an inclined paper machine capable of layer paper making can be used.

Example 1 Polymetaphenylene isophthalamide 1 of polymetaphenylene, isophthalamide (logarithmic viscosity in sulfuric acid 1.5)
0 parts was dissolved in 90 parts of N,N-dimethylacetamide containing 5 parts of Licl, and this solution was introduced into an aqueous glycerin solution in a homomixer with high speed stirring to obtain a pulp-like material. The Canadian Standard Freeness (csf) of this product was 80 ml. Silicon nitride whiskers (average fiber length 100μ, diameter 0.5μ)
10 parts were added to 500 parts of water, and the mixture was mixed with a homomixer (manufactured by Tokushu Kika Kogyo) to prepare a whisker dispersion slurry. Next, 100 parts of Slur IJ-1 containing 1 part of the above pulp-like material as a solid content was added to this slurry and mixed to obtain a uniform dispersion. Then, 30 sheets were obtained by hand-shaping according to the conventional method. The resulting sheet has whiskers uniformly dispersed, and the tensile strength of the sheet is 0.2Q.
Kv/25+an, excellent handling workability. The ash content of the sheet was 90.2 q6.

Example 2 A dispersion slurry of whiskers and pulp-like material was obtained in the same manner as in Example 1. Next, 30 parts of a 0.01% aqueous solution of a high molecular weight cationic polyacrylamide, Percoll 57 (manufactured by Allied Colloids), was added to this slurry and mixed. Make paper by the usual method, 30 f/rr? I got a sheet of The texture of the sheet has whiskers that are a bit clumped together.
The tensile strength of the sheet was the same as in Example 1, although the sheet had a slight tendency to flock. Also, the ash division was 90.696.

Example 3 NBKP was beaten to obtain a beating degree of csf500m/, 350
-1200- and 80- pulp slurries were obtained. Silicon carbide whiskers (average fiber length 40μ, diameter 0.2μ) 1
0 part was added to 500 parts of water and dispersed at 600 Or, p, m using a homogenizer (Nippon Seiki Seisakusho) to obtain four uniformly dispersed slurries of whiskers. To this slurry, 1.5 f of each pulp slurry having a pulp solid content of which the beating degree had been changed was mixed to obtain four types of slurries. Next, add 30% of Percoll 57 0.01% solution to each.
The slurry was added in portions at a time, and hand papermaking was performed using this slurry.

In hand-making, a slurry is collected using a wire of 80 td, and after dehydration, felt or paper is brought into close contact with a wet sheet on the wire and pressed to transfer it to felt or paper. When using pulp with a high freeness, the wet paper could not be transferred from the wire. On the other hand, the transfer was possible only when using 80 f pulp, and subsequent press-drying was carried out without any problems, and 40 f
/r? sheets were obtained. This sheet was easy to handle.

Example 4 Silicon carbide whiskers (average fiber length 10μ, -diameter 0.1
μ) 10 parts were treated in the same manner as in Example 1 to obtain 500 parts of a rice car dispersion slurry. Next, 100 parts of Slur IJ containing a pulp-like material with a solid content of 1 part was added, and anionic polyacrylamide (Star Gum A-15: manufactured by Seiko Kagaku) was added.
0.5 part was added and mixed with stirring. Furthermore, cationic polyacrylamide (Polystron 619; manufactured by Arayo Kagaku) 0.
5 parts were added and mixed with stirring. Using this slurry, υ hand-sheeting was carried out in a conventional manner to obtain 50 sheets. The resulting sheet had a tensile strength of 0.6 Kp/25m5+ and was easy to sweep. Also, the whisker distribution in the sheet was uniform.

Claims (1)

[Claims] A method for producing a whisker sheet, which comprises integrally forming an aqueous composition comprising whiskers and a fibrous material having a freeness of 100 csf.