JPS6385171A - Conductive fiber and its production - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to conductive fibers, and more specifically to conductive materials, resistance materials, antistatic materials, static electricity removal prevention materials, electromagnetic shielding materials, etc. that require conductivity. It is a material for conductive composite materials that can be applied to materials such as conductive inks, paints, etc.
This invention relates to conductive fibers that can be widely used in fields that require high conductivity, such as sheet molded products.

(Prior art) In recent years, with the diversification of needs regarding conductive materials, the development of highly conductive compositions and molded products has been desired, and the development of highly conductive fillers that are suitable as materials for conductive composite materials has been desired. Although desired, highly conductive fillers include gold, silver, platinum,
16'j metal powder such as palladium or carbon powder,
Anything other than carbon powder is expensive, and these powdered highly conductive fillers are non-reinforcing fillers, and if a large amount of conductive filler is used to increase conductivity, the strength will drop significantly, making it difficult to use as a composition. A high level of skill is required for selection of formulations for adjusting if1 of physical properties and conductivity, process control during manufacturing, etc.

Carbon # as a reinforcing filler! There are fibers, but the fiber lengths are uneven, making them unsuitable as materials for conductive composite materials that require precision. The present inventor has developed various conductive alkali metal titanate fibers as a conductive filler with excellent reinforcing properties, and has disclosed the technical contents thereof, and is currently applying for a patent for a silver-coated conductive composition. Although conductive fibers can be obtained by manufacturing methods using these electroless plating baths, when used as a material for composite materials, there are problems such as an increase in the coating layer film (1) and a decrease in the surface smoothness of the coating layer. Although it is superior to conductive substances, it has problems such as not being able to fully utilize the properties of fibers as a base material.

(Problems to be Solved by the Invention) The purpose of the present invention is to provide a highly conductive klkm that is suitable as a material for conductive composite materials that require precision and that can fully utilize the characteristics of fibers as a base material. It's about r.

(Means for Solving the Problems) The present invention provides a conductive M&fiber characterized in that the surface of the aJli material is crested with one or a mixture of two or more of et gold metals and its oxides, and a method for producing the same. Pertains to.

In the present invention, the fibrous material has a fiber shape with an aspect ratio (ratio of fiber diameter to fiber diameter) of 10 or more, and the fiber length is determined from the viewpoint of processability when used as a conductive composition. 1 micron ~: 100 mm, fiber at diameter is IONm ~ 1
+n+n is preferable, including gypsum fiber, asbestos, rock wool, quartz fiber, alumina fiber, carbon fiber,
Silicon carbide fiber, silicon nitride fiber, norconia fiber, boron nitride fiber, boron carbide Jyt.

Examples include titanium boride fiber, boron fiber, beryllium oxide fiber, magnesium pyroborate IAjIt, alkali metal titanate fiber, alkaline earth metal titanate fiber, and the like.

In particular, alkali metal titanate Wt fibers having a composition represented by the general formula M20·nTioz (the middle part of the formula is an alkali metal, and n means an integer from 2 to 12), such as sodium titanate
Among the 7-mutaatt, potassium titanate fibers, and titanate titanate fibers, potassium titanate fibers have excellent heat resistance and mechanical strength, and when used as a filler, have excellent surface smoothness and reinforcing properties. It's advantageous.

The invention! Metals are gold, silver, platinum group metals, and A
Examples include utAgvPttPa and the like, and a conductive coating layer made of one or more of these metals and metal oxides is formed, but silver and silver oxide are practically preferred because they are inexpensive.

In the present invention, the I? Although there are no particular restrictions on
It is necessary that the coating is homogeneous; if it is too thin, the conductivity will be insufficient, and if it is too thick, it will not only be wasteful from an economical point of view, but also be coated with fish scales or aggregates of granular materials. 1 nm because it tends to result in an irregular surface with many unevenness.
A range of ~1 μm is preferred.

A second invention of the present invention relates to an advantageous method for manufacturing the electrically conductive fiber of the first invention.

That is, one component necessary for the reduction of the noble metal compound is added to the a) aqueous dispersion of the fibrous material, of the components consisting of the a) aqueous solution or aqueous dispersion of the metal compound, c) the reducing agent, and 2) the reduction catalyst. Add the remaining ingredients and complete the reduction of the noble metal compound under stirring.Continuously add the remaining essential ingredients to homogeneously form a thin film of metal or noble metal oxide on the surface of the fiber material. The specific method is as follows: 1) a) fJ & textile material dispersion a) aqueous solution or aqueous dispersion of a noble metal compound b) 9)
A method in which a reducing agent is added under stirring to a mixture of the above or a reducing catalyst added thereto, 2) A) Aqueous dispersion of a fibrous substance A) An aqueous solution or aqueous dispersion of a noble metal compound C) A reducing agent I 9) A method of adding a reducing catalyst to the mixed solution of (9) and (3) under stirring; 3) A method of adding a reducing catalyst to the mixed solution of (9) and (3) under stirring; 3) A method of adding a reducing catalyst to the mixed solution of 9) and (3) adding a reducing catalyst to the aqueous dispersion of the fibrous material in a reducing atmosphere, and then adding an aqueous solution or dispersion of the noble metal compound under stirring Examples include a method of adding a liquid, etc., but the method is not limited to methods of separately preparing and mixing the components shown in methods 1) to 3) above, and these reactions can be substantially performed. As the process progresses, each component may be added to the same aqueous dispersion medium simultaneously or sequentially.

In this invention #! The aqueous dispersion of the IL fiber material can be obtained by the usual powder dispersion method, but the preferred method is to add the fiber material to an aqueous solvent under stirring, and at this time, remove as much miscellaneous material as possible. It is desirable that the fibers be defibrated; if the defibration is insufficient, it will be difficult to form a conductive jacket NWI uniformly, and the resulting conductive fibers will have insufficient conductivity. Therefore, when preparing an aqueous dispersion, commonly used dispersion aids, such as water-soluble organic solvents and surfactants, may be used in combination.
Since it is preferable that the fiber material exhibit sufficient fluidity, the ratio of the aqueous dispersion medium to the fibrous material is in the range of 1:10 to 1:1000, preferably 1:50 to 1:500.

In the present invention, nitrates, hydrochlorides, cyanides, etc. are exemplified as water-soluble compounds of the noble metal compound, and the aqueous solution of the present invention is obtained by dissolving these water-soluble compounds in water, and the aqueous solution of the noble metal compound is By adding hydrolyzing agents and chelating agents such as alkali hydroxide, ammonia, ethylenenoaminetitraacetic acid and its alkali salts, precious metal compounds are precipitated from an aqueous solution as fine colloidal particles, resulting in a homogeneous aqueous system consisting of noble metal compounds. A dispersion is obtained, and in the present invention, rather than using an aqueous solution of a noble metal compound,
When using an aqueous dispersion of a noble metal compound prepared by the method described above, more favorable results were obtained in terms of conductivity, film homogeneity, etc. An aqueous reducing substance that reduces a part of the noble metal compound is added to an aqueous solution of the compound to reduce the metal compound and colloidal particles of the noble metal are precipitated. A dispersion in which colloidal particles of a noble metal element are precipitated in an aqueous solution of a reducing substance by adding a portion of the reducing substance may also be used.

In the present invention, stabilizers commonly used in aqueous solutions and dispersions of noble metal compounds, such as water-soluble organic solvents, inorganic acids, organic acids, chelating agents, surfactants, etc., may be added.

In the present invention, the concentration of the aqueous solution and aqueous dispersion of the noble metal compound is not particularly limited, and it is sufficient that the solubility of the noble metal compound is higher than the solubility of the noble metal compound. This concentration is such that a colloid of an element is precipitated and forms a stable dispersion, and it is generally preferred to use a concentration of 0.1 to 50% by weight. In the present invention, the effect of the presence of colloidal particles of a noble metal compound or a noble metal element on the formation of a conductive film has not been fully elucidated, but e.g.
When the t-metal compound is reduced and precipitated together with metal elements, these colloidal particles first deposit on the surface of the fibrous material and form wtP4 nuclei, and when the subsequent noble metal compounds are reduced and precipitated, the colloidal particles are deposited around these nuclei. This is thought to be because the liquid metal film grows and becomes a homogeneous film.

In the present invention, the reducing agent refers to one that reduces a noble metal compound by itself or in the presence of a reduction catalyst, such as formaldehyde, sodium periosulfate, tartaric acid and its salts, hydrazine and its salts, hydrogen peroxide, barium peroxide, There are peroxides that exhibit reducing properties in the coexistence of alkali such as calcium peroxide, and examples of reduction catalysts include alkali metal compounds such as potassium hydroxide and potassium hydroxide.

In the present invention, there are no particular restrictions on the form in which the reducing agent and reducing catalyst are used, but aqueous solutions are generally preferred, and hydrazine, hydrogen peroxide, etc. are particularly unstable, so it is convenient to use hydrates or aqueous solutions.Others The reducing agent and reducing catalyst may have a concentration higher than the solubility, but it is usually about 5 to 70%.
Used in a concentration of % by weight.

In the present invention, it is preferable to use a colloidal solution obtained by adding an aqueous solution of a noble metal compound to an aqueous solution of the reducing agent or reducing catalyst to precipitate a noble metal element, since a homogeneous noble metal coating can be obtained.

In the present invention, the ratio of the noble metal compound to the reducing agent may be at least the stoichiometric amount required for reducing the d-metal compound, but usually the reducing agent is used in excess, and about 1
A range of 20 equivalents is preferred.

As explained above, the conductive fiber of the present invention can be produced by adding a reducing agent to a homogeneous mixture of fiber Mt, an aqueous dispersion of a substance, and a homogeneous mixture of an aqueous solution or an aqueous dispersion of a metal compound.
t' to a system in which a reducing agent was added to an aqueous dispersion of the IL41i substance.
A method in which an aqueous solution or dispersion of a metal compound is added, and a reduction catalyst is added to an aqueous dispersion of Wl, an arsenic substance, a noble metal compound is added, and a reducing agent activated by a reducing catalyst is added. However, it is preferable to always use these reaction solutions in a homogeneous dispersion system; if the dispersion is insufficient, the coating layer tends to become non-uniform. Note that any commonly used stirrer or dispersion rock can be used for these dispersions, and when proceeding with the reaction, it is preferable to continuously add the last component to be added, and these reduction reactions should be carried out at around room temperature. However, if the reaction generates heat, cool it to 10-40℃, and if it does not, heat it to 2.
It is best to carry out the reaction at a temperature of 0 to 50°C; in any case, if the temperature is higher than 70°C, the reaction will be too rapid and the surface will become uneven.
On the other hand, if it is below O'C, the reaction will be slow, resulting in poor productivity, etc.
There is α.

Furthermore, in the present invention, a commonly used dispersion stabilizer, tlFT
Dispersion stabilizers such as J agent and i++1 foaming agent, reaction regulators, etc. may be used in combination.

The conductive fibers of the present invention can be produced in the examples shown below, but in order to improve their conductivity, they are reprocessed in a reducing atmosphere such as reduction firing to improve their conductivity. It can also be increased.

(Effects of the Invention) The conductive fiber of the present invention is an excellent functional material that exhibits high conductivity without losing any of the original characteristics of the fiber material as a material for composite materials. It is extremely suitable for needs such as antistatic materials and static electricity removal materials, and according to the manufacturing method of the present invention, the conductive a-fiber of the present invention can be easily manufactured at an extremely low cost with good reproducibility. can.

(Example) A detailed explanation will be given below with reference to examples.

Example 1 Potassium titanate #thm <Otsuka Chemical Co., Ltd., Teismo p)
ig homogeneously dispersed in 100ml of water, add 4g of silver nitrate
After dissolving in 100ml of water, ammonia water (concentration 28%)6
ml of potassium titanate fibers was added to obtain a homogeneous solution, thereby obtaining an aqueous dispersion of potassium titanate fibers in which silver nitrate was dissolved. Next, add 20g of separately prepared potassium/sodium tartrate to 200ml of water.
A solution of 10.6 g of nitric acid dissolved in 20 + nl of water was added to the solution in 1, and the reducing solution, in which silver was colloidally dispersed in an aqueous sodium tartrate solution, was stirred and the reaction temperature was raised to 30 mL.
While maintaining the temperature at ~40°C, it was added to the aqueous dispersion of potassium titanate fibers for 30 minutes, and then stirred at 30°C for 30 minutes.
After aging for 0 minutes, deposit! Separately, *By drying,
The surface of the potassium titanate fiber is uniformly coated with reduced silver to a thickness of 15 nm, and the specific volume resistivity is 2. lX10-'Ω
3.9 g of grey-white conductive potassium titanate a-fiber of em was obtained.

For comparison, Example 1 except that the amount of silver nitrate dissolved in the aqueous dispersion of potassium titanate #a was 4.6 g, and no silver nitrate was added to the potassium sodium tartrate aqueous solution.
In the same method as above, 3.4g of dark brown fiber-like material was obtained.
However, the conductivity was 6.3×10 −1 ΩcIIl, which was insufficient.

Example 2 2X10 of ethylenediaminetetraacetic acid disodium salt
20 g of silver nitrate was added to water I under stirring in a molar aqueous solution 4001
A solution dissolved in QOml was added to obtain a colloidal dispersion in which part of the silver nitrate was chelated.

Add 6g of potassium titanate fiber (Teismo D) to the above dispersion.
To the dispersion of potassium titanate fibers in which some silver nitrate was colloidally dispersed, 200 ml of 30% hydrogen peroxide was added, and the noble metal compound (nitric acid I) and reducing agent (peroxide) were added. An aqueous dispersion of potassium titanate aM# was obtained. While stirring the above dispersion, 50 ml of a 5N aqueous sodium hydroxide solution was added dropwise over about 30 minutes to 10-15°C on an ice-water cooling bath, and then a portion of the reaction dispersion was collected and dried separately. The thing is potassium titanate al! It was a dark brown conductive fiber having a coating layer having a thickness of 10 n +11 on which silver oxide was uniformly precipitated with reduced silver as the core, and a volume specific resistivity of 2.4 x 10 -' Ωcm.

Add 5N hydroxide to the remaining reaction dispersion above) + 7 um 1
After adding 50 ml, 300 ml of 30% hydrogen peroxide was added dropwise over 30 minutes while stirring and kept at 10 to 15°C on an ice-water cooling bath, and dried to a thickness of about 10 ml.
coated with reduced silver with a volume resistivity of 3.9×10
18.2 g of gray-white conductive fibers of -4ΩcI11 were obtained during sampling.

Example 3 20g of sodium/potassium tartrate in 200ml of water
10 ml of a 30% aqueous solution of silver nitrate was added dropwise to the solution under stirring to obtain a reduced solution in which reduced silver was dispersed in a colloidal state. Potassium titanate fibers (Otsuka Chemical Co., Ltd., Teismo L) Ig were added to this reducing solution to obtain an aqueous dispersion in which potassium titanate fibers were dispersed in the reducing solution.

While stirring the above dispersion, maintain the reaction solution at 30 to 40°C, and dissolve 3.7 g of separately prepared silver nitrate in 200 ml of water. An aqueous solution containing a noble metal compound containing barley and 6 ml of 28% ammonia water was added dropwise over a period of about 30 minutes, and after aging for another 30 minutes, the surface of the potassium titanate fibers was dried to form reduced silver. 3.4 g of grayish-white conductive fibers having a volume resistivity of 4.3×IQ-4Ωc111 was obtained, which was uniformly coated with a thickness of 12 nm.

Example 4 Potassium titanate [t (Teismo D) Ig was homogeneously dispersed in 300 ml of 4N hydrochloric acid, 1 part of 80% hydrazine hydrate was added, and 40 g of a 10% solution of chloroauric acid in hydrochloric acid was added. was added under stirring to obtain an aqueous dispersion of potassium titanate fibers containing a noble metal compound.

After adding 80% hydrazine hydrate 1001 dropwise to the above-mentioned dispersion on an ice-water cooling bath while stirring for about 30 minutes while adjusting the reaction temperature not to exceed 30°C, it was aged at 30°C for 2 hours. , separately, by drying, potassium wham titanate #a
, the surface of the material is homogeneously coated with reduced gold to a thickness of 9% and 1%,
Orange-red conductive a41t3. with a specific volume resistivity of 1.8X10-Ωel11. Got Igwo? =.

(that's all)

Claims (11)

[Claims] (1) A conductive fiber characterized in that the surface of the fiber material is coated with one or a mixture of two or more noble metals and their oxides. (2) The conductive fiber according to claim 1, wherein the noble metal is Pt, Au, Ag, or Pd. (3) The conductive fiber according to claim 1, wherein the coating layer has a thickness of 1 nm to 1 μm. (4) The conductive fiber according to claim 1, wherein the fiber material is an alkali metal titanate fiber. (5) A) Adding to the aqueous dispersion of the fibrous material, b) an aqueous solution or aqueous dispersion of a noble metal compound, c) a reducing agent, and d) a reducing catalyst among the components consisting of the above b), c), and d), a noble metal. One component necessary for the reduction of the compound is omitted and the remaining component is added, and the remaining essential component is continuously added to complete the reduction of the noble metal compound under stirring, and the surface of the fiber material is coated with the noble metal or the oxide of the noble metal. A method for producing conductive fibers characterized by forming a homogeneous thin film. (6) A) Aqueous dispersion of fibrous material b) Aqueous solution or dispersion of noble metal compound a), b)
6. The method for producing conductive fibers according to claim 5, wherein a reducing agent is added to a mixed solution of the above or a reducing catalyst added thereto under stirring. (7) A) Aqueous dispersion of fibrous material B) Aqueous solution or aqueous dispersion of a noble metal compound C) Reducing agent A reducing catalyst is added to the mixture of a), b), and c) under stirring. 5. The method for producing a conductive fiber according to item 5. (8) After adjusting the aqueous dispersion of the fibrous material to a reducing atmosphere,
6. The method for producing conductive fibers according to claim 5, wherein an aqueous solution or dispersion of a noble metal compound is added under stirring. (9) In forming a thin film made of a noble metal or an oxide of a noble metal on the surface of a fibrous material homogeneously, an aqueous dispersion in which colloidal particles of a noble metal compound or a noble metal element coexist is used. Method for manufacturing conductive fibers. (10) The method for producing conductive fibers according to claim 5, wherein the noble metal compound is Pt, Au, Ag, or Pd. (11) The method for producing a conductive fiber according to claim 5, wherein the fiber material is an alkali metal titanate fiber.