JPS5825368A - Electrically conductive coating composition - Google Patents

Abstract

PURPOSE:To provide the titled compsn. forming a strong film with a high electric conductivity, prepared by addint to a highly conductive fluoropolymer, a specified metal compd. which forms a condensation film under heating or a water- soluble organic polymer which decomposes and volatalizes at the burning temp. of the fluoropolymer. CONSTITUTION:The coating compsn. contains (A) 5-40wt% fluoropolymer[e.g., tetrafluoroethylene (co)polymer], (B) 5-40wt% electrically conductive pigment (e.g., graphite or copper powder), (C) 5-50wt% hydrophilic organic solvent (e.g., carbitol), (D) 1-30wt% surfactant (e.g., nonionic surfactant with an HLB value of 10-20), (E) 0-60wt% water, (F) 0.15-15wt% silane or quadrivalent Ti, Zr or Sn compd. (e.g. omega-aminoalkyltrialkoxysilane and tetraethyl titanate) and/or (G) 0.005-1wt% water soluble organic polymer which decomposes and volatalizes at the burning temp. of the fluoropolymer (e.g. gelatin or PVA).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fluoropolymer coating composition containing a conductive pigment.

Fluorine-containing polymers have excellent heat resistance, chemical resistance, and solvent resistance.
Moreover, it has unique non-adhesive and self-lubricating properties, so it is widely used for non-adhesive, mold release and lubrication purposes.

In recent years, attempts have been made to impart conductivity to such fluorine-containing polymers, particularly polytetrafluoroethylene, by blending them with conductive pigments.

For example, JP-A-49-11911 discloses a polytetrafluoroethylene coating composition containing conductive carbon. In the case of this composition, the weight ratio of conductive carbon/polytetrafluoroethylene is 3 to 15.
/100, the conductivity is low, and the electrical resistivity of the obtained film is approximately 75 to 103 g·α. Therefore, among the uses of conductors such as static electricity removal and heating elements, this composition can only be used for static electricity removal and cannot be used for heating elements.

On the other hand, Japanese Patent Publication No. 4B-17663 discloses a method for producing a polytetrafluoroethylene dispersion.

In the case of the dispersion obtained by this method, the weight ratio of conductive material/tetrafluoroethylene is as high as 1/1,
As a result, the electrical conductivity of the obtained film is also high (electrical specific resistance of approximately 0.3 to 2 Ω·cm). Therefore, this dispersion is a material that can be applied to static electricity removers, heating elements, etc., but when formed into a film, the coating strength is weak and the range of application during processing is narrow.

In general, in a fluorine-containing polymer coating composition containing a conductive pigment, increasing the ratio of the conductive pigment to the fluorine-containing polymer increases the conductivity, but on the other hand, the strength of the film when formed into a coating decreases. A contradictory phenomenon can be seen.

An object of the present invention is to overcome the drawbacks of the prior art and to provide a fluorine-containing polymer coating composition that has high conductivity and provides a film with excellent film strength.

This purpose of the present invention is as follows: (a) 5 to 40% by weight of the fluoropolymer; (b) 5 to 40% by weight of the conductive pigment; (C) 5 to 50% by weight of the hydrophilic organic solvent; (d) the interface. 1 to 30% by weight of an activator; and (e) 0 to 60% by weight of water, further comprising (') silane or a tetravalent titanium, zirconium or tin compound which decomposes on heating to form a condensation film. and/or (g) 9.005 to 1% by weight of a water-soluble organic polymer material that decomposes at the firing temperature of the fluororesin and at least part of it evaporates. This is achieved by a conductive coating composition characterized by containing.

Examples of the fluorine-containing polymer used in the composition of the present invention include tetrafluoroethylene resins, ie, tetrafluoroethylene homopolymers or copolymers containing 75% by weight or more of tetrafluoroethylene. Examples of the comonomer used in the copolymer include ethylene, flopene, hexafluoroglobene, vinylidene fluoride, trifluorotrichloroethylene, and perfluorovinylethernato. Further, as the fluorine-containing polymer, a fluorine-containing elastic copolymer can also be used alone or in combination with the tetrafluoroethylene resin.

Examples of the fluorine-containing elastic copolymer include tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer, vinylidene fluoride-hexafluoropropylene copolymer, and tetrafluoroethylene-propylene copolymer.

The fluorine-containing polymer is used in an amount of 5 to 40% by weight, preferably 10 to 20% by weight, based on the composition.

Examples of conductive pigments include graphite such as scaly graphite or earthy graphite; conductive carbon, that is, carbon whose particles have a highly continuous structure (for example, Lion Akzo Co., Ltd.: KetjenISlack E, C,
:) Mouth 7 Bien Carbon Company: Conductex
95 Q, etc.); and metal powders such as nickel powder, silver powder, copper powder, and aluminum powder.

The conductive material is used in an amount of 5 to 40% by weight, preferably 10 to 20% by weight, based on the composition.

Examples of the hydrophilic organic solvent include carpitol, butyl carpitol, cellosolve, butyl cellosolve, -gamma-lactone, glycerin, polyglycerin, and ethylene glycol.

The reason for using such a hydrophilic organic solvent is as follows: For example, when mixing carbon with polytetrafluoroethylene, adding carbon directly to an aqueous polytetrafluoroethylene dispersion will cause the polytetrafluoroethylene to condense. Therefore, it is necessary to prepare the carbon in an aqueous dispersion in advance. As described above, carbon must first be dispersed in water, but if only a surfactant is used, the viscosity of the liquid increases, and only about 10% of carbon can be added. Ball mill crosstalk also becomes impossible. If such a low concentration carbon dispersion is used, the concentration of the final coating composition will be low, making it difficult to coat. If a hydrophilic organic solvent is present therein, the viscosity will not increase and a dispersion containing carbon at a high concentration can be obtained.

The hydrophilic organic solvent is preferably used in an amount of 10 to 20% by weight of the needle in the final composition of 5 to 50% by weight.

As the surfactant, any surfactant can be used, but nonionic or ionic surfactants with an HLBIO of 40 are preferred. In particular, HLBIO~20
A nonionic surfactant is desirable for its effect on stabilizing the dispersion. Specific examples of surfactants include polyoxyethylene oleyl ether as a nonionic surfactant;
Polyoxyethylene lauryl ether, polyoxyethylene nonylphenyl ether, and anionic surfactants include sodium lauryl alcohol sulfate and sodium dodecylbenzenesulfonate.

``The surfactant is used in an amount of 1 to 30% by weight, preferably 4 to 15% by weight, based on the composition.

Compounds capable of forming a condensation film include silane or tetravalent titanium, zirconium or tin compounds which can be polyhydrolyzed. Such compounds have at least 2 hydrolyzable groups, preferably at least 3 hydrolyzable groups, and especially for titanium, zirconium and tin, 4 hydrolyzable groups. This is desirable. By hydrolyzing such compounds, their halide or oxyhydrocarbon groups can be replaced with hydroxyl groups, and these compounds are converted into polyhydroxy compounds. The polyhydroxy compound is dehydrated and condensed by heating to form repeating units: 1 [wherein M represents silicon, titanium, zirconium or tin]. Unsaturated valences are saturated with hydrolysable groups, hydrolyzable groups of such groups, or repeating units. ] forming a network of alternating silicon or metal atoms and oxygen atoms. In the case of silane, each silicon atom is bonded to at least one aliphatic carbon atom.

To further explain each condensation product in detail, in the case of titanium, the condensation product is characterized as a product consisting of condensable tetravalent titanium oxide units: TiO-. Among these, the products obtained by thermal decomposition are thought to have a network structure with units of 1.

Compounds capable of hydrolyzing titanium include titanate esters, for example, formula: % formula % [wherein k' is alkyl, aryl, or carbon number 1-8
cycloalkyl; P represents an integer of 0 to 3; ] Orthoesters or acrylates of orthoticunic acid; chelates of titanium, such as formula: T 1
(OR') (OX YR') 4p [wherein, Y is a 2 or 3 carbon chain; X represents oxygen or nitrogen.

k' and p have the same meanings as above.

However, when X is oxygen, one k′ bonded to it
exists, and when X is nitrogen, two k bonded to it
′ exists. ] The compounds shown in the following are exemplified. At the above ceremony R
/ may be hydrogen, except that it is a compound from which orthotitanic acid is obtained. Specific examples of hydrolyzable titanate esters include tetraalkyl titanates (e.g., tetraethyl titanate, tetraisoglobil titanate, and tetrabutyl titanate), tetraethylene glycol titanate, triethanolamine titanate, titanium-acetyl titanate. Included are prepolymers obtained by reaction of acetonate, titanium lactate, and tetraalkyl titanate with water.

For zirconium, compounds similar to titanium can be used, thus the formula: Z r (OR' ) Z r (0COR' )
(ok') p o4・4-
p and Z r (OR') p (OX Y R'n4
-pr In the formula, R', y, x and P have the same meanings as above. ]
Compounds shown can be used. Specifically, tetraalkyl zirconates (eg, tetraethyl and tetrabutyl zirconate) and water-soluble chelates thereof.

The silane may be expressed, for example, by the formula: % Formula % [In the formula, D represents a hydrolyzable functional group; B represents an organic group containing a carbon atom bonded to a Si atom. E is D or B
Represents either. ] A compound represented by these is used. Where two B groups are present, at least one of these has an aliphatic carbon attached to the silicon atom of the formula. Examples of bases include halogen,
Examples include cl or F: alkoxy, preferably alkoxy having 1 to 5 carbon atoms: aryloxy, such as phenoxy or naphthoxy; and acetoxy. directly or indirectly, for example to an alkylene group (where X is an integer from 2 to 12, preferably from 3 to 9) ;-(CH2)yNH(CH2),
NHK (where y is an integer from 2 to 4, 2 is an integer from 1 to 4, and k is 11, methyl or ethyl):
and (C112)x (CFI 3) , where X is as defined above. Suitable silanes include amine-functional silanes, such as omega-aminoalkyltrialkoxysilanes, such as gamma-
Aminopropyltriethoxysilane, meta- and para-aminophenyltriethoxysilane, and N (n-
Propyltrimethoxysilyl)ethylenediamine is included.

Hydrolysis and thermal decomposition of such silanes yields repeating units: 1 [wherein the free valence is another hydrolyzable group, its hydrolyzable group, or a similar repeating unit (bonded by an oxygen atom]). saturated. However, at least one bond in each silicon atom is bonded to an aliphatic carbon atom. ] A condensation product is formed.

The polyhydrolysable compound of tetravalent tin can be an organic or inorganic compound, such as S n Cl 4 . The hydrolysis/condensation products of such tin compounds are formed by repeating units 1 C, where the free valence ' is a hydrolyzable group, a hydrolyzable group of such a group, or a similar repeating unit (oxygen bonded by atoms). ] It has.

The amount of the compound capable of forming such a condensation film is 0.915 to 15% by weight, preferably 0.2% by weight based on the composition.
It is used in a proportion of ~3.0% by weight.

The water-soluble organic polymer material decomposes at the firing temperature of the fluororesin, and at least a portion thereof evaporates.

Polymeric materials used in the present invention include natural polymers such as gelatin and gum arabic, semi-natural polymers such as methyl cellulose, polyvinyl alcohol, water-soluble phenolic resin, water-soluble alkyd resin, sodium alginate, polyethylene oxide, and acrylamide resin. Examples include synthetic polymers such as and melamine-modified resins.

The water-soluble organic polymer material is 0.005 to
It is used in a proportion of 1% by weight, preferably 0.01 to 0.1% by weight.

The composition of the present invention can generally be prepared by the following method. First, components (b), (C), (d) and (e>
are mixed to form a dispersion or paste, and this is mixed with an aqueous dispersion of the fluorine-containing polymer. Ingredients ('') and (
g) can be added at any step.

Next, examples and comparative examples will be shown to specifically explain the present invention.

Example 1 (1) Preparation of conductive pigment paste 510 grams of graphite powder and 9 grams of conductive carbon powder
Butylcarpitol 6002 was added to 09, and a nonionic surfactant (polyoxyethylene octylphenyl ether) 20% aqueous solution 1 was added to this.
00 (l) with stirring, and stirred and mixed to uniformly wet the mixture. Next, water goof! in which 48 g of 2.5% methyl cellulose aqueous solution was dissolved was added with stirring to obtain a viscous mixture. The mixture is placed in a ball mill and kneaded for about 10 hours to finely disperse the pigment.About 3000 g of the resulting Puco pigment paste contains about 20% by weight of the conductive pigment.

(2) Preparation of conductive coating composition An aqueous dispersion 33 containing 60% by weight of polytetrafluoroethylene particles in the pigment paste 100P obtained in (1)
f! , ion exchange water 41F! , 2.4 g of a 20% by weight aqueous solution of r-aminopropyltriethoxysilane was added with stirring and mixed uniformly to form an aqueous dispersion of 176.45 i
got '.

Example 2 Ethylcarpitol 1322 was added to 612 grams of graphite powder and 11 grams of conductive carbon while stirring, and 220 grams of a 20% aqueous solution of a nonionic surfactant (polyoxyethylene octylphenyl ether) was added in the same manner to form a solid. Wet the ingredients evenly. Next, 176.75' of water in which 5.72% of a 2.5% methylcellulose aqueous solution is dissolved is added with stirring to obtain a viscous mixture. This mixture is placed in a ball mill and mixed for about 10 hours to finely disperse the pigment.

The pigment paste thus obtained, about 6005i', contains about 12% conductive pigment (by weight).

Aqueous dispersion 20f containing 60% by weight of polytetrafluoroethylene particles in this pigment paste 100F! and 1.52 y of a 20% by weight aqueous solution of r-aminopropyltriethoxysilane were added with stirring and mixed uniformly to obtain 121.5 y of an aqueous dispersion.

Examples 3-5 Instead of graphite powder and conductive carbon powder,
Silver powder (average particle size 0.3μm 6001 Example 3), nickel powder (average particle size 0.2μm) 600g (Example 4)
Alternatively, using copper powder (average particle size 0.2 μm) 600S' (Example 5), the same procedure as in Example 1 was repeated to obtain an aqueous dispersion.

Examples 6-7 Example 1 without r-aminopropyltriethoxysilane (Example 6) or methylcellulose (Example 7)
The same procedure as above was repeated to obtain each aqueous dispersion.

Comparative Example 1 An aqueous dispersion was obtained by repeating the same procedure as in Example 1 without using r-aminopropyltriethoxysilane and methylcellulose.

A coating film was created using the aqueous dispersion obtained in the above Examples and Comparative Examples, and its tensile strength and electrical resistance were measured. 0+m) using a doctor knife to a uniform thickness. After leaving it at room temperature for 15 minutes, it was dried for 20 minutes in an atmosphere whose temperature was adjusted to 120-150°C using an infrared lamp, and then heat-treated at 380°C for 15 minutes in an electric furnace to bake the polytetrafluoroethylene resin contained therein. and make it into a film. The aluminum plate with the film formed thereon is immersed in 6N hydrochloric acid for 60 minutes to completely dissolve the aluminum portion. Finally, a film containing fluororesin and conductive pigment remains. This film is washed with water and used for measurement.

Measurement of tensile strength of film A test piece film measuring 159 ma+ in length, 20 mm in width, and about 20 μm in thickness is pulled at a rate of 10 g/min in a room temperature atmosphere, and the film strength at break is measured.

Electrodes held between copper foils are attached to both ends of a similar test piece in the longitudinal direction, and a current of Q, lmA is applied to measure the voltage at 4 or more points at a distance of 60 mm along the longitudinal direction of the film. The electrical specific resistance R is calculated by the following formula: R=lQVS - [where V is the measured voltage and S is the lateral cross-sectional area, ie width x thickness unit d). ] The thickness was measured at several points and the average value was used.

The measurement results are shown in Table 1.

Representative 1: Attorney Masu Buri, Qingbai Bo (and 2 others), Commissioner of the Japan Patent Office, 1. Description of the case, 1982 Patent Application No. 1'24380, 2. Name of the invention, Conductive coating composition 3. Person making the amendment. Relationship to the case Patent applicant address: New Hankyu Building, 1112-39 Ume Il-1-chome, Kita-ku, Osaka-shi, Osaka Prefecture (285) Representative of Daikin Industries, Ltd. Yama 111 Minoru 48, Agent 5, Date of amendment order (Attachment) 7. The following parts of the statement of amendments will be amended.

■Claims column As per attached sheet.

■Detailed Description of the Invention Column (1) Page 4, line 8, "1% by weight" was revised to "5% by weight"i'F.

! 2114 Kan line 11, [1% by weight...0.1% by weight] is replaced with "5% by weight, preferably 0.01 to 1% by weight"
Heavy #Qi, special: 0.01-0.1% by weight,” it was corrected.

Claim 1 (Al-containing fluoropolymer 5-40 pigment 5-40 weight #%; (C) hydrophilic organic solution ~15-50
(d) surfactant 1-30% by weight; and (e
) containing 0 to 60% by weight of water, and further containing () 0.15 to 15% of silane or a compound of tetravalent titanium, zirconium or tin which can be decomposed by heating to form a condensation product. weight?%; and/or (g
) A water-soluble organic polymer material that decomposes at the firing temperature of the fluorine-containing polymer and at least a part of it evaporates from 0.005 to
A conductive coating composition characterized in that it contains 5% by weight.

2. The conductive coating composition according to claim 1, wherein the surfactant is a nonionic surfactant of 1-IL810 to 20.

Claims (1)

[Claims] 1. (a) fluorine-containing polymer 5-40% by weight; (b) conductive pigment 5-40% by weight; (C) hydrophilic organic solvent 5-50% by weight
(d) surfactant 1-30% by weight; and (e
) Contains 0 to 60% by weight of water, and (f) 0.15 to 15% by weight of a silane or a tetravalent titanium, zirconium or tin compound which can be decomposed by heating to form a condensation film. %: and/or (g
) A conductive coating composition characterized by containing 0.005 to 1% by weight of a water-soluble organic polymer material that decomposes at the firing temperature of the fluororesin and at least part of it evaporates. 2. The conductive coating composition according to claim 1, wherein the surfactant is a nonionic surfactant with an LBIO of LBIO to 20.