JPS6181443A - Magnetic cellulosic material and its preparation - Google Patents

Abstract

PURPOSE:To produce a magnetic cellulosic material having high flexibility, light weight and excellent moldability, and suitable as an electromagnetic wave shielding material, electrical radiation absorbing material, etc., by impregnating a solution of a metallic salt composed mainly of iron in a celulosic material, and precipitating the metal oxide in the material. CONSTITUTION:A cellulosic material (e.g. paper, wood pulp, etc.) or activated cellulosic material is impregnated with a solution of metallic salt composed mainly of iron, and the metal oxide is precipitated by the control of pH and temperature, heating, electrolysis, etc. The metal oxide composed mainly of magnetic iron can be precipitated in the cellulosic material.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic cellulosic material and a method for producing the same.

[Industrial application field]

In recent years, digital equipment, dense electronic equipment, and IC.

With the spread of LSI and other circuit parts, problems such as interference with magnetic waves and magnetic interference have become a problem, and the need for electromagnetic shielding, wave absorption, and magnetic shielding is increasing.

The present invention provides a magnetic cellulose-based material that is soft, lightweight, and has excellent moldability and is suitable for use as an electromagnetic shielding material, a radiowave absorbing material, a magnetic shielding material, and other magnetic materials, and a method for producing the same. .

[Conventional technology]

The conventional method for imparting magnetism to cellulose-based materials is to first manufacture a powdered magnetic substance, then disperse it in a solution of 11 g of synthetic or natural binder to form a magnetic coating liquid, and then apply it to the cellulose-based materials. is being carried out. However, in this coating method, in preparing the coating liquid, it takes a long time to perform operations for uniformly dispersing the magnetic material particles into the resin as a binder. Furthermore, several coating steps are required when coating cellulose-based materials, and in this case, only the surface layer has magnetism.

[Problem that the invention seeks to solve]

The purpose of the present invention is to improve the drawbacks of magnetic cellulose materials obtained by the above-mentioned techniques, and to make use of the characteristics of cellulose materials, such as hydrophilicity and porousness, to make them economical and easy to operate. Specifically, it is an attempt to obtain a cellulose-based material that is flexible, at-temperature, has good moldability, and has a high magnetic effect.

In other words, (1) no synthetic resin or natural binder is used, (2) the cellulose thread material and the magnetic substance are brought into close contact with each other, and (3) a continuous film of the magnetic substance is formed. The purpose of this study is to economically obtain a magnetic cellulose material with reduced magnetic properties.

[Means to resolve the problem]

The present inventors have discovered that by impregnating a cellulose-based material or a cellulose-based material that has been previously activated with a solution of metal salts mainly containing iron, and then performing a precipitation operation such as heating or electrolysis, the desired magnetic cellulose can be obtained. The present invention has been achieved by discovering that these materials can be used.

That is, the first invention of the present invention is a magnetic cellulose-based material in which a gold MfR compound mainly composed of iron and gold is precipitated to have magnetism in the cellulose-based material. Further, the second invention is to precipitate a magnetic metal oxide mainly composed of iron from a cellulosic material or a cellulosic material that has been previously activated and impregnated with a metal salt solution mainly composed of iron. This is a method for producing a magnetic cellulose-based material.

In the magnetic cellulose-based material of the present invention, the precipitation it'f of the magnetic metal oxide can be varied from 1 to several hundreds of degrees based on the weight of the cellulose, and is uniformly precipitated.

Moreover, magnetic cellulose-based materials in the form of powders, fibers, and sheets can be easily obtained. In addition to having agitated magnetic properties, this magnetic cellulose-based material has a much lower specific gravity, is rich in flexibility, and has good moldability compared to single materials of magnetic metals and magnetic metal oxides.

Furthermore, by compounding it with other materials such as plastics or other cellulose materials, a magnetic material with even lighter motion can be obtained. It is expected to exhibit superior performance because it is lighter, more elegant, and easier to form than conventionally commercially available magnetic shielding materials, electromagnetic wave shielding materials, radio wave absorbing materials, and other magnetic materials.

In the present invention, the metal salts include ferrous salts, ferric salts, mixtures of ferrous salts and ferric salts, or these salts containing Li, Na, Cu + Ag*, respectively.
Mg * Ba, Zn, AI I Ti +
Sn * Pb * V e Sb aCr r Mo
Preferably, one or more types of metal salts such as e Mn + Fs * Co * N1 are appropriately selected and combined. Although there are various types of iron salts and other metal salts mentioned above, sulfates and chlorides are preferred from the viewpoint of ease of availability and economical efficiency,69 and more preferably water-soluble sulfuric acid salts. Salts and chlorides are preferred.

As a means of precipitation from these iron-based gold IA salt Ml solutions to cellulose materials, under pB and temperature control,
Heat treatment, electrolysis treatment, etc. or a combination thereof is used. Through this precipitation treatment, a magnetic metal oxide mainly composed of iron is deposited on the cellulose material.

When these precipitation treatments are carried out in a full magnetic field, the degree of magnetic orientation of the precipitated magnetic material increases, which is effective in improving the magnetic properties of magnetic cellulose-based materials.

A wide range of cellulosic materials can be used, ranging from pure cellulose to lignocellulose, but sheet-like materials include paper, boards, cotton cloth, etc., and fibrous materials include prefecture white pulp and unprocessed materials. Various wood pulps up to white pulp, cotton, regenerated cellulose cotton, etc., and powders such as microcrystalline cellulose, wood powders (e.g., wood flour), cellulose-like products (e.g., starch), etc. Can be mentioned.

These cellulosic materials are subjected to treatment with a metal salt solution either as they are or after being activated in advance. In this case, activation treatment methods include various oxidizing agents, υ whose functional groups such as aldehyde groups are increased in the material through oxidation treatment such as corona discharge treatment, glyoxal having aldehyde groups, dialde L do starch, and formaldehyde resin systems. There is a method of imparting an aldehyde group by attaching a compound or the like to a cellulose-based material, or a method of attaching a surfactant or a drug having a surfactant effect.

As a precipitation means, such a cellulose-based material is immersed in a metal salt solution, the pH and temperature of the solution are adjusted, and heat treatment and, if necessary, introduction of an oxygen-containing gas are used in combination. Such a precipitation operation causes hydrolysis and oxidation of the metal salts, and a magnetic metal oxide magnetic material mainly composed of iron is precipitated on the cellulose material.

Others soak cellulosic materials at different temperatures (p)
When an electric current is passed through a metal salt bath solution in which l is adjusted, a magnetic substance is deposited on the cellulose material due to hydrolysis and oxidation of the metal salt.

In addition, in these precipitation treatments, the specific method of pH adjustment can be easily carried out by conventionally known methods, and in order to uniformly precipitate the magnetic material on the cellulose material, the type of p11 adjuster and its It is desirable to select and adjust the addition rate appropriately. Final pH during precipitation treatment is 5-1
3 is desirable, but the preferred range varies depending on the type of metal salt and pHI adjuster, precipitation treatment method, etc. For example, when salts of amphoteric metals such as zinc or aluminum are included, a magnetic material having the desired composition will not precipitate unless sufficient attention is paid to pH adjustment. For example, when nickel or cobalt salts are included, if a PA adjuster such as ammonia or amines is used, these metals will form a carp body, so that a magnetic material of the desired composition will not be precipitated. The atmosphere during precipitation is not particularly limited, but for example, a metal salt solution containing iron as a main component, or a precipitated magnetic metal oxide may be oxidized more than necessary, resulting in poor magnetic properties such as coercive force and saturation magnetic flux density. If this is undesirable due to a decrease in the concentration, the atmosphere may be adjusted and selected as appropriate, such as by performing precipitation under an inert atmosphere.

[Effect]

The magnetic substance deposited on the cellulose material by such a precipitation treatment or a combination of these adheres well to the cellulose material and does not fall off when washed with water, etc., so it is not necessary to use pH adjusters, unreacted metal salts, or pH adjusters. Substances that are undesirable when using the obtained magnetic cellulose material, such as salts produced by the reaction between the agent and metal salts, can be removed by washing with water or the like. After washing with water and drying, a magnetic cellulose material having desired magnetic properties with excellent weather resistance and abrasion resistance is obtained. Furthermore, this magnetic cellulose material has flexibility and excellent moldability, and has sufficient strength, so that a good magnetic composite material can be obtained by combining it with other materials.

〔Example〕

Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to the following practical examples.

Example 1 Softwood albumen pulp 100 beaten to freeness 400-
f t A 1% D degree slurry was prepared. While stirring, add 1 mol/l of ferrous sulfate solution to this slurry, and add 1 mol/l of ferrous sulfate solution to 435 m/l of ferric sulfate solution.
and - adjust the pH to 11-12 with sodium hydroxide.
After 14i, the pulp changes from reddish brown to black.

When this slurry is heat-treated at 90° C. for 0 minutes, the ferrous and ferric salts are almost entirely magnetized.1- They precipitate into the pulp as magnetic iron oxide, which is the main component.

After washing this magnetic iron oxide precipitated pulp with water,
When paper is made to a weight of 60 t/-g and dried at 105°C, a black magnetic paper is obtained.

The precipitation rate of the magnetic substance on the obtained magnetic paper is 100% of the pulp
In weight percent, its magnetic properties are coercive force 970e.

Residual magnetic flux density 8.6 emu/f, saturation magnetic flux density 25
, Oemu/r, and magnetic permeability was 12.1.

The magnetic properties were measured using a vibrating sample type direct current magnetization property automatic recording device manufactured by Denshi Magnetic Industry Co., Ltd.

The following measurements of magnetic properties were also carried out by colleagues.

Example 2 Hardwood pulp was beaten to a total 7-ness of 250 mm, and paper was made into paper with a basis weight of 60 r7.2 in a conventional manner to obtain a wet paper. This wet paper was treated with corona discharge to increase the amount of aldehyde in the pulp to 5.0 mmol per 100 f of pulp. This activated wet paper 100 ft-
Redisperse in water to make a 2-layer slurry. 1 mol μ of ferric chloride bath solution 870− was added to this slurry, and heated while stirring well until it boiled, thereby adsorbing F@3+ ions to the pulp. To this Fe ion absorption pulp slurry, 1 mo17'L of ferrous chloride was added so that the molar ratio of ferric chloride, ferrous chloride, and nickel chloride was 2:1:1.
Iron solution 435-1l mol/j Nickel chloride solution 43
After adding 5- and stirring well, the - of the system was adjusted to 10 to 11 kg with sodium hydroxide, and heat treated at 90°C for 1 hour to obtain magnetic pulp in which magnetic iron oxide containing nickel oxide was precipitated. It will be done. After washing this magnetic pulp with water, it is made into paper using a conventional method and dried at 105°C to form a paper sheet of 60 f/m.
magnetic paper was obtained.

The rate of precipitation of the magnetic substance on the obtained magnetic paper was 100 mm per pulp, and its magnetic properties were 50 e.

Residual magnetic flux level 10-9 emu/? , saturation magnetic flux density 2
It had a magnetic permeability of 9.0 emu/l and a magnetic permeability of 19.4. Saturation magnetic flux density by containing nickel oxide,
A magnetic cellulose material with improved magnetic permeability was obtained.

Example 3 100 ml of unbleached oblique-leaved pulp was beaten to a freeness of 500 ml to prepare a 1 ml slurry. While stirring this slurry, 1 not/L ferrous chloride solution 870-
Add 435 mol/l mol/of cobalt chloride solution and adjust the pH of the system to 10-11 K with sodium hydroxide,
When heat treated at 90° C. for 9 minutes, a magnetic pulp in which magnetic iron oxide containing cobalt oxide is precipitated is obtained.

This magnetic pulp is made into paper by a conventional method and dried at 105°C to obtain a magnetic paper with an area of 60 f7m.

The amount of magnetic material deposited on the obtained magnetic paper was 100 times the weight of pulp, and its magnetic properties were 6600 @ coercive force.

Residual magnetic flux density 10-6 mmolf, saturation magnetic flux density 22
・0@mu/f, magnetic permeability was 5.4. By containing cobalt oxide, a magnetic cellulose material with significantly improved retention ability was obtained.

Example 4 Beech wood flour (80 mesh pass) 100IP t-10
When suspended in 2 L of aqueous solution of 5% periodic acid and treated at room temperature for 5 minutes, 100% of wood powder was obtained. 30 mmol
aldehyde groups are formed. After washing this oxidation-activated wood powder with water, l mol/was added to a ferrous chloride solution of 600-1
1mo 1μ manganese chloride solution 200ml, 1mo
Prepare 200 l of zinc chloride solution, suspend it in the 9 mixed liquid, continue stirring for 1 hour, and thoroughly soak the solution into the wood flour. Adjusted to include When this wet wood powder is chewed in an ammonia gas atmosphere, it becomes black in color. Next, by heat treatment with hot air at 80° C., a magnetic main powder in which magnetic iron oxide containing manganese oxide and zinc oxide is precipitated is obtained. It was thoroughly washed with water to remove impurities and dried again.

The rate of precipitation of the magnetic material into the obtained magnetic wood powder was lt-chi with respect to the weight of the wood powder, and its magnetic properties were a coercive force of 190e and a residual magnetic flux density of 0.
．． 7 mmolf, saturation magnetic flux density 10-5 mmol
f.

The magnetic permeability was 9.6. By containing manganese oxide and zinc oxide, a magnetic cellulose material with coercive force and residual magnetic flux density smaller than the saturation magnetic flux density was obtained.

〔Effect of the invention〕

The results obtained in Examples 1 to 4 above are summarized in Table 1.

Table 1 In the present invention, it is possible to precipitate magnetic metal scrap oxide, which is mainly composed of iron, as a uniform and continuous film on cellulose-based materials, and the amount of the precipitated film can be freely controlled.

Furthermore, since the magnetic properties of the obtained magnetic cellulose material can be freely controlled, it is possible to economically provide a flexible, lightweight, and moldable magnetic material that has a magnetic effect depending on the application.

Claims (2)

[Claims] (1) A magnetic cellulose-based material in which a magnetic metal oxide, mainly iron, is deposited on the cellulose-based material. (2) The feature is that a magnetic metal oxide mainly composed of iron is precipitated from a cellulosic material or a cellulose material that has been previously activated and impregnated with a solution of metal salts mainly composed of iron. A method for producing a magnetic cellulose material.