JP2002348468A - Electroconductive polyamide composite and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electroconductive polyamide excellent in electroconductivity, heat resistance, dimensional stability and toughness. SOLUTION: A method of manufacturing an electroconductive polyamide composite is to contact (A) an aqueous solution phase containing water, water glass and a diamine and (B) an organic solution phase containing an organic solvent and a dicarboxylic acid monomer in the presence of (C) an electroconductive particle. An electroconductive polyamide composite thus obtained is also provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polyamide composite having excellent conductivity, heat resistance, dimensional stability, and toughness, and a method for producing the same.

[0002]

2. Description of the Related Art Polyamide is known as an engineering plastic having excellent mechanical and chemical properties.
Polyamides are not inherently conductive, but can be mixed with conductive particles to make conductive plastic materials useful as electromagnetic wave shielding materials and antistatic materials, as disclosed in JP-A-60-108428 and JP-A-60-108428. Sho 61-26646
No. 0 publication. However, although this material is electrically conductive, the polyamide used is inferior in heat resistance, and thus has problems such as deterioration of characteristics at high temperatures and dimensional change due to heating. Improvement in this respect is desired. I was In addition, when used in a film or the like, the interfacial adhesion between the conductive particles and the polyamide is not sufficient, so that interfacial peeling is likely to occur, and there is a problem that the toughness is not sufficient.

On the other hand, the present inventors have already disclosed in Japanese Patent Application Laid-Open No. Hei 10-176106 a polyamide composite which is excellent in surface altitude, linear thermal expansion characteristics and the like and which is obtained by uniformly compounding fine glass. However, nothing is mentioned here about excellent conductivity due to coexistence of glass and conductive particles.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a conductive polyamide having excellent heat resistance, dimensional stability and toughness, and a method for producing the same.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that a ternary composite comprising conductive particles, glass and polyamide obtained by a specific manufacturing method. The body solves the above problems, and more surprisingly, by the coexistence of conductive particles and glass,
The present inventors have found that they exhibit better conductivity than the prior art, and have completed the present invention.

That is, the present invention provides an aqueous solution phase (A) containing water, water glass and diamine, and an organic solution phase (B) containing an organic solvent and dicarboxylic acid halide, by forming conductive particles (C). An object of the present invention is to provide a method for producing a conductive polyamide composite, wherein the conductive polyamide composite is brought into contact in the presence of the compound and a polycondensation reaction is carried out at an interface between both solution phases.

Further, the present invention provides a conductive polyamide composite obtained by the above production method.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
In the present invention, in the presence of the conductive particles (C), an aqueous solution phase (A) containing a diamine and an organic solution phase (B) containing a dicarboxylic acid halide are subjected to a polycondensation reaction under an interface to form a polyamide. obtain. In this case, the conductive particles (C) may be present in a form dispersed in the aqueous solution phase (A) and / or the organic solution phase (B). Above all, when the conductive particles (C) are contained in the aqueous solution phase (A) and the interfacial polymerization reaction is performed in a state where the conductive particles and water glass coexist, a part of the water glass is formed on the surface of the conductive particles. The reaction is performed in a state of being adsorbed, and the glass and the conductive particles are preferably taken into the polyamide in a state of being in good contact with the glass.

In the present invention, when the interfacial polycondensation reaction is carried out, water and glass coexist in the aqueous phase (A), whereby a fine and uniform composite of polyamide and glass is formed, The particles (C) are taken in uniformly.

The aqueous phase (A) contains water, water glass and diamine as essential components. The term “water glass” used herein means an alkali metal, silicon and oxygen as main constituent elements.
_It refers to a water-soluble glass having a composition formula of 2O · nSiO ₂ (M indicates an alkali metal). In the present invention, the glass component containing no water is defined as water glass.
In the above composition formula, M is preferably an alkali metal such as sodium or potassium, and the range of n is preferably 1.2 ≦ n ≦ 4 from the viewpoint of excellent solubility in water. One of the features of the present invention is that water glass can be directly used without any pretreatment such as hydrolysis with various acids or silylation.

The concentration of the water glass in the aqueous phase (A) is preferably in the range of 4 to 100 g / L (L = liter). If the glass concentration is less than 4 g / L, a sufficient amount of the composite to the polyamide will not be formed, and
If it exceeds L, the solution becomes highly viscous or the glass cannot be uniformly dispersed. The glass content in the composite can be controlled by adjusting the glass concentration.

The diamine is not particularly limited as long as it is a diamine monomer generally applicable to interfacial polycondensation. For example, 1,4-diaminobutane, 1,6-diaminohexane, p-phenylenediamine, m-phenylenediamine , M-xylylenediamine.

The concentration of the diamine in the aqueous phase (A) is not particularly limited as long as the polycondensation reaction proceeds sufficiently, but is preferably in the range of 0.01 to 5 mol / L. If the concentration condition is outside the above range, a problem that a sufficient yield cannot be obtained tends to occur. The aqueous solution phase (A) is obtained by adding water glass and a diamine to water, and the order of addition is not particularly limited. When adding the water glass, an aqueous solution in which the water glass is dissolved in water in advance may be used. It is possible.

For example, Japanese Industrial Standards (JIS K140)
8-1950) water glass No. 1, No. 2, No. 3, No. 4,
Water glass (M ₂ O · n)
In the composition formula of SiO ₂ , M is sodium;
2 ≦ n ≦ 4) is convenient and preferred.

An acid acceptor such as sodium hydroxide and / or a surfactant such as sodium lauryl sulfate may be added for the purpose of sufficiently promoting the polycondensation reaction of the monomer. Acid acceptors neutralize the protons released by the reaction, and surfactants increase the efficiency of contact between the monomers and promote the reaction. However, in many cases, polyamide can be sufficiently produced without using an acid acceptor or a surfactant. Incidentally, the water glass itself is also basic and also has an action as an acid acceptor, thereby promoting the formation of polyamide.

The organic solution phase (B) contains an organic solvent and a dicarboxylic acid halide as essential components. Examples of the organic solvent include those generally used for interfacial polycondensation, and typical examples include toluene, xylene, chloroform, dichloromethane, cyclohexane, tetrahydrofuran, 1,3-dioxolane, and the like.
The concentration of the dicarboxylic acid halide in the organic solution phase (A) is not particularly limited as long as the polycondensation reaction proceeds sufficiently, but is preferably in the range of 0.01 to 5 mol / L.

As the dicarboxylic acid halide, generally,
The monomer is not particularly limited as long as it is a monomer applicable to interfacial polycondensation.For example, adipoyl chloride, azelaoil chloride, sebacyl chloride, isophthaloyl chloride, terephthaloyl chloride and one or more of these aromatic rings And dicarboxylic acid halides in which hydrogen is replaced by halogen, nitro group or alkyl group.

The conductive particles (C) are not particularly limited, but include carbon materials such as carbon and graphite (including carbon black, carbon nanotubes and carbon nanofibers) and fibers of metal materials such as stainless steel, brass and steel. , Milled fiber, amorphous, spherical particles and the like. In particular, when it is desired to take advantage of lightness, a carbon material is advantageous. The conductive particles (C)
It may be used in a form dispersed in the aqueous solution phase (A) and / or the organic solution phase (B) described above.

These conductive particles are contained in the composite in an amount of 3 to 6%.
It is preferably present at 0% by weight, especially 20 to 50% by weight. If it is less than 3% by weight, the conductivity of the composite is insufficient, and
If the amount exceeds the weight percentage, the toughness is often insufficient.

The method for preparing the solution phases (A) and (B) is not particularly limited. For example, the above components may be added to a solvent and stirred at room temperature. At this time, each component may be dissolved in the solvent in advance and added in the form of a solution. In a state where the conductive particles (C) are not added,
It is preferable that both the aqueous solution phase and the organic solution phase are uniform. The reaction is carried out by bringing the aqueous solution phase (A) into contact with the organic solution phase (B). The aqueous solution phase may be added to the organic solution phase, or conversely, the aqueous solution phase may be added to the organic solution phase. The addition may be performed all at once or by dropping.

The conductive particles are added in a form dispersed in the aqueous solution phase (A) and / or the organic solution phase (B), and the polymerization is carried out in a state where the conductive particles are present at the interface between the two solution phases and in the vicinity thereof. Thus, the conductive particles are uniformly incorporated into the resulting polyamide. The conductive particles may be present in either the aqueous solution phase (A) or the organic solution phase (B), and the dispersion state is not particularly limited. It is common to do. By the presence of the conductive particles (C) in the water-soluble phase, the reaction is carried out in a state where a part of the water glass is adsorbed on the surface thereof, and the glass and the conductive particles are satisfactorily adhered to each other in the polyamide. It is preferable in that it is incorporated.

As the reaction temperature, the rate of the polycondensation reaction is extremely high, so that the reaction can be carried out at normal temperature. Therefore, the reaction can be performed at room temperature without particularly requiring any heating equipment. For example, the reaction can be preferably performed in a temperature range of -5 to 70C. The reaction time depends on the reaction rate of the monomer species used, but usually a precipitate is instantaneously formed by bringing the aqueous solution phase and the organic solution phase into contact with each other, and the reaction operation can be completed in, for example, 2 to 30 minutes.

It is preferable to stir both solution phases during the reaction, because the contact efficiency between (A) and (B) is increased. As described above, the water glass present in the aqueous solution phase (A) is uniformly incorporated into the polyamide generated by the interfacial polycondensation reaction, and a composite of glass and polyamide is obtained. Usually, under stirring conditions, the mixed solution comprising both solution phases (A) and (B) is a suspension containing the product.

One of the features of the present invention is that the hydrolysis and dehydration-condensation of water glass progress as shown in the following general formulas (1) and (2) with the compounding of water glass into polyamide. In addition, it is possible to incorporate very finely (glass diameter = 8-300 nm) into polyamide as a silica-type glass having an extremely small alkali metal component.

[0025]

[0026]

The silanol groups on the surface of the glass formed at this time are preferably bonded to the surface of the conductive particles, and a strong adhesion is obtained, which is effective for the development of toughness. In addition, when the conductive particles and the glass component coexist, the conductive particles and the glass component adhere to each other, and exhibit more excellent conductivity.

The complex thus obtained can be separated by removing components other than the complex from the mixed solution after the reaction. As a typical method of the separation, a method of filtering a mixed solution after the reaction is mentioned. After the filtration, a step of washing with an organic solvent or water may be introduced in order to completely remove unreacted monomers and by-products. For example, first, it can be washed with a solvent such as acetone or methanol, then washed with water, and then filtered. In particular, when the polyamide is of an aliphatic type, it is easy to obtain as pulp-like fine fibers (fiber length = 30 to 2000 μm can be exemplified), so that it is excellent in papermaking properties.
It is suitable for application as a conductive paper product.

After filtration, it is preferable to dry at a temperature higher than room temperature. Drying may be performed under reduced pressure or vacuum. At the time of such filtration, the composite can be obtained as a conductive paper product using a paper machine. Since the composite is easily obtained as pulp-like fine fibers, particularly when the polyamide is of an aliphatic type, the composite has excellent papermaking properties and is suitable for application as a conductive papermaking product.

The glass fraction (% by weight) in the composite can be suitably controlled by setting conditions such as the concentration of water glass in the aqueous solution phase (A) during synthesis. In general, a high water glass concentration gives a high ash content. For example, by setting the water glass concentration in the aqueous solution phase (A) to 8 g / L, 15 g / L, and 40 g / L, the glass fraction in the composite is 20 g / L, respectively. Weight% or more,
It becomes possible to make it 40% by weight or more and 60% by weight or more. The glass component can be finely dispersed on the surface of the nylon matrix and the conductive particles as ultrafine particles of 8 nm to 300 nm.

The conductive polyamide composite of the present invention has a small thermal expansion due to the excellent reinforcing effect of the finely dispersed glass and does not melt even at a temperature higher than the melting point of the matrix polyamide, for example, at a temperature exceeding the melting point. The shape can be maintained. Changes in characteristic values such as elastic modulus at high temperatures are small, and characteristic degradation during heating, which is a problem at a temperature higher than the glass transition temperature of polyamide, is suppressed. In addition, since glass is suitably bonded to the surface of the conductive particles and strong adhesion is obtained, it is excellent in toughness and conductivity. The conductive polyamide composite obtained by the present invention has an advantage that the surface hardness is also excellent.
The conductive plastic material containing the conductive polyamide composite of the present invention is useful as an electromagnetic wave shielding material, an antistatic material, a conductive filter material, a sheet heating element and the like.

[0032]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the Examples illustrate typical embodiments of the present invention and do not limit the scope of the present invention. The evaluation method in the examples is as follows.

(1) Conductivity The conductivity of the film at 25 ° C. was determined using a multi-tester CP7D manufactured by Sanwa Electronics. (2) Tensile test Using a 3 mm-wide film strip as a test piece, a tensile test was conducted at 25 ° C. at an initial gauge interval of 10 mm and a pulling speed of 1 mm / min using a universal testing machine Autograph 2000 manufactured by Shimadzu Corporation. The modulus of elasticity, strength, and elongation at break were each determined as an average of four measurements.

(3) Storage elastic modulus Dynamic solid viscoelastic property evaluation device (manufactured by Seiko Denshi Kogyo, D
MS200), 2 ° C./min heating rate, gauge length 1
5mm, 1Hz tensile mode, 20 ℃ under nitrogen atmosphere
The storage modulus of the paper was determined in the temperature range of 〜200 ° C.

(4) Hardness Dynamic ultra-micro hardness tester (DUH-2 manufactured by Shimadzu Corporation)
00), the dynamic hardness value of the flat plate at a test load of 10 gf at 25 ° C. was determined. (5) Linear thermal expansion coefficient Thermo-mechanical property measurement device (TMA / SS manufactured by Seiko Denshi Kogyo)
120C) in air at a heating rate of 2 ° C./min.
The average coefficient of thermal expansion at -30 to 30 ° C was measured. The calculation of the coefficient was based on the equation described in ASTM, D696. (6) Transmission Electron Microscope Observation Using a microtome, the observation sample was made into an ultra-thin section having a thickness of 55 nm. The obtained ultrathin section was observed with a microscope (JEM-200CX, manufactured by JEOL) at a magnification of 100,000 times.

(Example 1) Aqueous solution of water glass (Sodium silicate solution (No. 3) manufactured by Kishida Chemical Co., Ltd.)
Na ₂ O · 3.1 SiO ₂ , moisture = 60% by weight) 3.6
g, 4.64 g of 1,6-diaminohexane, and a uniform transparent 300 m obtained by stirring while adding distilled water at room temperature.
2.0 g of carbon black (Electric Black) manufactured by Denki Kagaku Kogyo was dispersed in the aqueous solution of L to obtain an aqueous solution phase. Also,
Toluene was added to 7.32 g of adipoyl dichloride at room temperature and stirred to obtain a uniform and transparent 200 mL organic solution phase.

A 1 L capacity blender bottle (Osterizer)
Solution phase), and the attached stirring blade is set to 9000 / min.
The organic solution phase was added all at once at 30 ° C. while rotating and stirring. A black complex was immediately precipitated from the mixed solution, and stirring was continued for 2 minutes in a suspended state. After filtering the obtained complex, it is washed with boiling acetone and then with distilled water, and then the liquid dispersed in water is passed through a papermaking apparatus having a 150 μm opening, and dried at 80 ° C. in vacuum to obtain a black color. A composite of carbon black, glass and polyamide was obtained as a papermaking product.

This paper product was compression molded at 290 ° C. and 20 MPa to form a 120 μm thick film. The transmission electron microscope observation of the film confirmed that the glass component was present in nylon 66 as spherical glass fine particles having a diameter of about 100 nm, and that carbon black having a diameter of 40 μm was uniformly dispersed in the composite matrix. In addition, 17 sheets of the above film are laminated, and 290 ° C., 20MP
a) to obtain a composite flat plate having a thickness of 2 mm. Tables 1, 2 and 3 show the results of the properties and properties of the above-mentioned paper, film, and flat plate.

Example 2 The procedure of Example 1 was repeated, except that 3.76 g of the aqueous solution of water glass was replaced with 30 g, and 2.0 g of carbon black was replaced with 4.5 g. Of carbon black, glass and polyamide was obtained as a papermaking product. Next, this was compression-molded with a hydraulic press machine at 320 ° C. and 800 MPa to obtain a composite flat plate having a thickness of 2 mm. Tables 1, 2, and 3 show the results of the properties and properties of the obtained paper, film, and flat plate.

(Comparative Example 1) The same operation as in Example 1 was carried out except that the water glass was omitted in Example 1, to obtain a composite comprising only black carbon black and polyamide as a papermaking product. Next, this was compression-molded at 320 ° C. and 800 MPa using a hydraulic press machine, and the thickness was 2 m.
m of the composite plate was obtained. The resulting paper, film,
Tables 1, 2, and 3 show the results of the properties and characteristics of the flat plate.

[0041]

[Table 1] Contents of conductive polyamide composite

[0042]

[Table 2] Tensile properties of thin films

[0043]

[Table 3] Physical properties of flat and paper products

[0044]

According to the present invention, a conductive polyamide having excellent conductivity, heat resistance, dimensional stability and toughness can be obtained.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Michiya Nakajima, 6-18-13 Yatsu, Narashino-shi, Chiba (72) Katsuharu Takahashi 5-21-2, Someino, Sakura-shi, Chiba F-term (reference) 4J002 CL031 DA027 DA037 DJ006 FA047 FD117

Claims (8)

[Claims] 1. An aqueous solution phase (A) containing water, water glass and diamine and an organic solution phase (B) containing an organic solvent and a dicarboxylic acid halide are contacted in the presence of conductive particles (C). And conducting a polycondensation reaction at the interface between the two solution phases. 2. The conductive polyamide composite according to claim 1, wherein the aqueous phase (A) contains the conductive particles (C), and the interfacial polymerization reaction is performed in a state where the conductive particles and water glass coexist. How to make the body. 3. The water glass is represented by a composition formula of M ₂ O · nSiO ₂ , wherein M is an alkali metal and 1.2 ≦ n ≦ 4. 3. The method for producing a conductive polyamide composite according to 1 or 2. 4. The concentration of water glass in the aqueous solution phase (A) is 4
-100 g / L, the concentration of diamine is 0.01-5 mol / L
L, the concentration of the dicarboxylic acid halide in the organic solution phase (B) is 0.01 to 5 mol / L, and -5 ° C to 70 ° C.
The method for producing a conductive polyamide composite according to any one of claims 1 to 3, wherein the reaction is performed at a temperature of: 5. The conductive polyamide composite according to claim 1, wherein 1,6-diaminohexane is used as a diamine and adipoyl dichloride is used as a dicarboxylic acid halide. Production method. 6. A conductive polyamide composite obtained by the production method according to claim 1. 7. The conductive polyamide composite according to claim 6, comprising 3 to 60% by weight of the conductive particles (C). 8. The conductive particles (C) are graphite,
The conductive polyamide composite according to claim 6, which is a carbon black, a carbon nanotube, or a carbon nanofiber.