JPH0754644B2 - White conductive material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to magnesium borate having an excellent reinforcing effect on plastics and the like and having conductivity.

(Prior art) With the development of science and technology and diversification of needs, development of high-performance and multifunctional materials is actively carried out, and various researches on development of conductive polymer materials are attempted even in the plastics industry. , For example carbon particles or fibers or copper,
A polymer material using a metal powder such as silver or gold as a conductive filler has been proposed. However, carbon particles, carbon fibers, and metal powders such as copper, silver, and gold each have a black or metal-specific color tone, which limits their use.
Moreover, these conductive fillers have no reinforcing property except carbon fiber. Carbon fiber is a reinforcing conductive filler, but it is difficult to make the fiber length uniform, and the aspect ratio is not uniform, so the moldability is poor, and the surface smoothness and abrasiveness of the molded product are poor. Inferior in.

(Problems to be Solved by the Invention) An object of the present invention is to provide a white conductive material which retains the original characteristics of magnesium borate.

Another object of the present invention is to provide a white electroconductive substance which can give a molded product excellent in molding processability, surface smoothness and abrasiveness.

(Means for Solving the Problems) The present invention is based on the general formula MgxByOz (x, y, z in which the surface is covered with tin oxide.
Represents a positive real number of 0 <x ≦ 4,0 <y ≦ 4,0 <z ≦ 10) and is a white conductive material containing magnesium borate as a main component.

The raw material of the present invention, magnesium borate, has the general formula MgxByO
z (x, y, z each represent a positive real number of 0 <x ≦ 4,0 <y ≦ 4,0 <z ≦ 10), and this magnesium borate is generally an ASTM powder X-ray. Diffraction cards 16-168 give an X-ray diffractogram similar to that of suunite, but with [201] plane and [4
02] It is unique in that the surface is well developed. The magnesium borate is also provided in the form of whiskers.

This magnesium borate whisker contains, for example, a magnesium supply component selected from magnesium oxide, hydroxide and inorganic acid salt, and a boric acid supply component selected from boron oxide, oxyacid and its alkali metal salt. , Sodium halide and potassium halide, in the presence of at least one kind of melting agent, it can be produced by heating to a temperature of 600 to 1000 ° C. to react.

As the magnesium supply component in this method, in addition to oxides and hydroxides of magnesium, magnesium compounds such as inorganic acids such as magnesium salts of carbonic acid, sulfuric acid, nitric acid and hydrohalic acid are used. Examples of such compounds include magnesium oxide, magnesium hydroxide, basic magnesium carbonate, magnesium sulfate, magnesium chloride, magnesium bromide and the like. These may be used alone or in combination of two or more.

Next, as a boric acid supply component, an oxide of boron, such as boron oxide, or an oxygen acid of boron, such as forthoboric acid (H ₃ BO ₃ ), tetraboric acid (H ₂ B ₄ O ₇ ), metaboric acid ( HBO ₂ )
Alternatively, these alkali metal salts such as sodium borate, sodium pyroborate, potassium pyroborate, and sodium metaborate are used. These may be used alone or in combination of two or more.

The magnesium supply component and the boric acid supply component are mixed at a molar ratio of magnesium to boron in the range of 1: 4 to 1: 1 and a melting agent is added in the range of about 10 to 95% by weight based on the total weight. Then, the desired magnesium borate whiskers can be produced by heating to a temperature in the range of about 600 to 1000 ° C. and reacting. The heating temperature at this time is 60
If the temperature is below 0 ° C, the reaction progresses extremely slowly, and 1000 ° C.
If it exceeds the above range, a large amount of triclinic prismatic magnesium borate is by-produced in addition to the desired magnesium borate whiskers, which is not preferable. The reaction time is usually in the range of 15 minutes to 2 hours.

To isolate the whiskers from this reaction product, they are first treated with hot or cold water to remove the melting agent and other water-soluble components. When there are by-products depending on the raw material composition used, the fibrous material is separated from the residue by means such as decantation, hydration and air bubble separation. Then, the crude magnesium borate whiskers thus obtained are treated with an alkali,
For example, pure magnesium borate whiskers can be obtained by removing impurities by washing with an aqueous solution of sodium hydroxide and an acid, for example, an aqueous solution of acetic acid or cold dilute hydrochloric acid.

In the X-ray diffraction spectrum, the magnesium borate whiskers thus obtained had a d-value of 4,47 [201] plane and a d-value of 2.47 as compared with ASTM powder X-ray diffraction card 16-168.
The diffraction intensity on the [402] plane of 823 is strong, and the d value of 2.557 is [012].
The diffraction intensity of the surface is relatively weak, and thus it can be identified as a fibrous compound.

Magnesium borate is generally a powder or fibrous single crystal, but in the present invention, any of these forms can be used. However, among them, fibrous substances are preferable, of which fiber length is 5 μm or more, aspect ratio is 20 or more, especially 10
Those of 0 or more are suitable as the reinforcing filler.

Magnesium borate in the present invention is white and can be used in combination with a colorant to give an arbitrary color tone. In order to obtain the object of the present invention, a general metal oxide forming method can be applied, but as the reinforcing conductive material, it is preferable that the conductive material is separated into a short fiber state, and the fine fiber state remains as it is. It is advantageous to subject the magnesium borate to a tin oxide coating. For example, an aqueous solution of tin chloride, an alcohol solution or an alcohol, a polyhydric alcohol, an aqueous solution or dispersion containing an organic solvent such as a water-soluble aldehyde is used.
A spray coating method in which the surface of magnesium borate heated to 0 to 900 ° C, preferably 400 to 800 ° C is sprayed and then reheated to deposit tin oxide on the surface of magnesium borate;
Magnesium borate is suspended in a fluidized bed in a non-oxidizing atmosphere in a suspended, suspended or sedimented state, and a tin compound is introduced under heating. If necessary, moisture or oxygen is introduced to oxidize the surface of magnesium borate. A chemical vapor deposition method of depositing tin; a so-called physical vapor deposition method of depositing magnesium borate on the surface of magnesium borate by vaporizing tin oxide under reduced pressure and heating after forming or molding magnesium borate can be applied.

Incidentally, as the tin compound applicable to these methods, any compound can be considered if the complexity of the process is ignored,
Tin chloride or its hydrate is advantageous in that it is less toxic, stable, and easy to control the treatment process. Also, a CVD method or a method of decomposing acetylacetone tin salt or acetylacetone antimony salt and showering on magnesium borate can be applied.

In the present invention, it is possible to improve the conductivity by artificially mixing a small amount of antimony, indium or the like when forming the tin oxide coating layer.

The conductive magnesium borate of the present invention is a plastic currently in practical use, for example, polyethylene, polypropylene, ethylene propylene diene polymer, polyester resin, polyamide resin, phenol resin, amino resin,
Epoxy resin, polyether resin, polyimide resin, polyacetal resin, polybutylene terephthalate resin,
It becomes a white composite material that is well miscible with any of polysulfone resin, polyether sulfone resin, etc. and has excellent conductivity and improved mechanical strength. Moreover, these composite materials are excellent in cutting, polishing, and flatness.

Further, the conductive magnesium borate of the present invention can be used in combination with a suitable polymer binder to form a conductive paint, a conductive ink, a conductive adhesive, a conductive tape, a conductive sheet, a conductive sealant, etc. It is applicable to various uses.

As described above, the present invention provides a conductive substance that can be easily manufactured and has excellent post-processability. A white or white conductive substance of the present invention is added to the conductive substance having black or colored reinforcing properties. By combining the above, it is possible to obtain a reinforcing conductive filler having an arbitrary color tone, which is excellent in heat resistance and surface smoothness.

(Examples) Hereinafter, examples will be described.

Example 1 10 g of fibrous magnesium borate was dispersed in 100 ml of water,
The mixture was stirred for 30 minutes with a stirrer to form a slurry. Next, this dispersion slurry is heated to 90 ° C. in an oil bath, and stannic chloride (SnCl ₄ · xH ₂ O manufactured by Hanai Chemical Co., Ltd.,
x: 4.8, containing 75% SnCl ₄ ] 16 g and 1.6 g of antimony chloride [SbCl ₃ manufactured by Hanai Chemical Co., Ltd.] in 3.7 N hydrochloric acid aqueous solution
The mixed solution dissolved in 30 g and 90 ml of 3.7 N aqueous sodium hydroxide solution were simultaneously added with stirring over about 1 hour while maintaining the liquid temperature of the hot slurry at 90 ° C. and pH 10 to 11.
The pH was adjusted to 7.5 with 7N hydrochloric acid, and the solution temperature was adjusted to 9
The mixture was stirred for 1 hour while maintaining it at 0 ° C. After that, the reaction solution was allowed to cool to room temperature, the solid matter was washed with water, dried, and then finely divided, and then heat-treated at 600 ° C. for 2 hours. Thus, white conductive fibrous magnesium borate was obtained.

The volume resistivity (the same applies hereinafter unless otherwise specified) of the conductive fibrous magnesium borate measured under a load of 100 kg / cm ² was 1.3 × 10 ² Ω · cm.

Example 2 Magnesium borate obtained in the same manner as in Example 1 except that antimony chloride was not used had a volume resistivity of 4.1 × 10 ⁴ Ω.
・ It was in cm.

Example 3 17 g of stannic chloride and 1.7 g of antimony chloride same as in Example 1
Was dissolved in 30 g of 3.7 N hydrochloric acid aqueous solution to prepare a mixed salt solution.

Then spread 10 g of magnesium borate on a porcelain dish to a thickness of 1 mm, heat the magnesium borate to 750 ° C while vibrating it on a zircon sand bath adjusted to 800 ° C, and use the above-mentioned adjustment liquid with a simple hand spray. Was sprayed onto the surface of magnesium borate. When spraying, the total amount is sprayed at 10-second intervals in 10 times, and then 750 minutes for another 5 minutes.
After keeping the temperature at ℃, it was transferred to drying adjusted to 300 ℃ and aged for 3 hours to obtain a white, fine fibrous conductive magnesium borate powder.

The conductivity was evaluated by using a tablet molding machine under pressure of 100 kg / cm ² to form tablets having a diameter of 12 mm and a thickness of 3 mm, and measuring the volume resistance of the tablets. Volume resistivity is 4.9 × 10 ²
It was Ω · cm.

Example 4 Example 3 was repeated except that the heating temperature and the post-treatment temperature of magnesium borate at the time of spraying the stannic chloride solution were changed to the conditions shown in Table 1.
Samples 41 to 45, which are white fine crystals, were prepared in the same manner as in. The evaluation of conductivity is shown in Table 1.

Example 5 Stannous chloride 80 parts Methyl alcohol 20 parts Stannous chloride alcohol solution (solution A) Antimony chloride 3.5 parts Methyl alcohol 96.5 parts Antimony chloride alcohol solution (solution B) A
Solution B and solution B were prepared as described above, and a treating solution having a mixing ratio (part) of solution A and solution B shown in Table 2 was prepared. Then, the surface of magnesium borate was treated with the mixed solution to give a white, fine powder. A conductive magnesium borate powder was obtained.

Example 6 25 g of fibrous magnesium borate was dispersed in 200 ml of water and stirred for 30 minutes with a stirrer to form a slurry, and the dispersed slurry was heated to 90 ° C. in an oil solution. In this hot slurry 3.
After adding 57.3 ml of 7N sodium hydroxide and mixing, 5.5 g of antimony trichloride was added to 62.4 g of a 45% aqueous solution of stannous chloride (as SnCl ₂ ) prepared in advance, and 3.7 g of 3.7N hydrochloric acid
An acidic mixed salt solution containing stannous chloride and antimony chloride prepared by adding a solution dissolved in ml and 52 ml of an 8.4 N sodium hydroxide aqueous solution were added in the same manner as in Example 1 over about 1 hour. After aging this hot slurry under stirring at 90 ° C for 1 hour, the pH was adjusted to 8.5 with 3.7N hydrochloric acid, insoluble matter was removed, washed with water, dried, and then heat-treated at 600 ° C for 2 hours to obtain white. A conductive fibrous magnesium borate was obtained. The volume resistivity of this magnesium borate was 7.2 × 10 ¹ Ω · cm. In addition, urethane paint [Dainippon Paint Co., Ltd.
V Top clear] dispersed in a ratio of 25 wt%, 40 μm after mixing
The thickness of the paper was applied to the paper, and after drying, this paper was exposed under a fluorescent lamp of 100 W under an irradiation distance of 60 cm and an irradiation time of 24 hours, and the light resistance was examined. It was shown below that it has good light resistance.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Misao Morinaga 463 Kagasuno, Kawauchi-cho, Tokushima City, Tokushima Prefecture Otsuka Chemical Co., Ltd. Tokushima Laboratory (72) Inventor Yuya Harayama 463, Kagasuno, Kawauchi-cho, Tokushima Prefecture (56) References JP-A-56-114216 (JP, A) JP-A-59-6235 (JP, A) JP-A-59-89337 (JP, A)

Claims (2)

[Claims] 1. A general formula MgxByOz having a surface covered with tin oxide.
(X, y, z are positive real numbers of 0 <x ≦ 4,0 <y ≦ 4,0 <z ≦ 10, respectively), which is a white conductive material containing magnesium borate as a main component. 2. The white conductive material according to claim 1, wherein the magnesium borate is fibrous.