CN112313279A - Liquid composition, laminate, heat exchanger, and method for producing corrosion-resistant coating film - Google Patents

Liquid composition, laminate, heat exchanger, and method for producing corrosion-resistant coating film Download PDF

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CN112313279A
CN112313279A CN201980040997.4A CN201980040997A CN112313279A CN 112313279 A CN112313279 A CN 112313279A CN 201980040997 A CN201980040997 A CN 201980040997A CN 112313279 A CN112313279 A CN 112313279A
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corrosion
liquid composition
resistant coating
conductive filler
laminate
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CN112313279B (en
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细田朋也
寺田达也
尾泽纪生
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AGC Inc
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Asahi Glass Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B1/00—Layered products having a non-planar shape
    • B32B1/08—Tubular products
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B15/00—Layered products comprising a layer of metal
    • B32B15/04—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B15/08—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • B32B15/082—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin comprising vinyl resins; comprising acrylic resins
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/01—Use of inorganic substances as compounding ingredients characterized by their specific function
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/02—Elements
    • C08K3/04—Carbon
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L27/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers
    • C08L27/02—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment
    • C08L27/12—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
    • C08L27/18—Homopolymers or copolymers or tetrafluoroethene
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D127/00—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Coating compositions based on derivatives of such polymers
    • C09D127/02—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Coating compositions based on derivatives of such polymers not modified by chemical after-treatment
    • C09D127/12—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Coating compositions based on derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
    • C09D127/18—Homopolymers or copolymers of tetrafluoroethene
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
    • C09D7/40—Additives
    • C09D7/60—Additives non-macromolecular
    • C09D7/61—Additives non-macromolecular inorganic
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F19/00—Preventing the formation of deposits or corrosion, e.g. by using filters or scrapers
    • F28F19/02—Preventing the formation of deposits or corrosion, e.g. by using filters or scrapers by using coatings, e.g. vitreous or enamel coatings
    • F28F19/04—Preventing the formation of deposits or corrosion, e.g. by using filters or scrapers by using coatings, e.g. vitreous or enamel coatings of rubber; of plastics material; of varnish

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Organic Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Polymers & Plastics (AREA)
  • Medicinal Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Wood Science & Technology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Inorganic Chemistry (AREA)
  • Laminated Bodies (AREA)
  • Compositions Of Macromolecular Compounds (AREA)
  • Paints Or Removers (AREA)

Abstract

The present invention provides: a liquid composition capable of forming a corrosion-resistant coating layer having excellent appearance and being reduced in variation in thermal conductivity, corrosion resistance and corrosion resistance; a laminate comprising a corrosion-resistant coating layer having excellent appearance and being reduced in variation in thermal conductivity, corrosion resistance and corrosion resistance; a heat exchanger; and a method for producing a corrosion-resistant coating film. A liquid composition comprising: containing a melt viscosity of 1X 10 at 380 DEG C2～1×106A layer forming component of Pa · s tetrafluoroethylene polymer powder and a conductive filler, and a liquid medium, wherein the sum of the proportion of the tetrafluoroethylene polymer and the proportion of the conductive filler in the layer forming component is greater than 75% by mass, and at least a part of the layer forming component is dispersed.

Description

Liquid composition, laminate, heat exchanger, and method for producing corrosion-resistant coating film
Technical Field
The present invention relates to a liquid composition, a laminate, a heat exchanger, and a method for producing a corrosion-resistant coating film.
Background
A boiler that generates steam from boiler water using combustion gas uses a heat exchanger having heat transfer tubes.
The combustion gas contains water vapor, sulfur oxides, and the like. Therefore, when the combustion gas reaches a temperature (sulfuric acid dew point temperature) or lower at which sulfuric acid is produced by heat exchange in the heat exchanger, sulfuric acid is produced in the heat exchanger, and corrosion of the heat transfer tubes and the like easily occurs.
As a heat transfer pipe of a heat exchanger capable of suppressing corrosion by sulfuric acid, there has been proposed a heat transfer pipe having a corrosion-resistant coating layer formed by attaching a mixture of dry powders of a fluororesin, carbon fiber, a lead-free solder alloy, graphite, and silicon carbide to the outer surface of a pipe main body by electrostatic coating and performing a firing treatment (see patent document 1).
Documents of the prior art
Patent document
Patent document 1: japanese patent laid-open publication No. 2013-164247
Disclosure of Invention
Technical problem to be solved by the invention
However, when a mixture of dry powders of the respective components is electrostatically coated, it is necessary to make the average particle diameter of each powder (particularly, the average particle diameter of the dry powder of the fluororesin) several tens of micrometers. Therefore, the corrosion-resistant coating layer formed tends to have uneven distribution of the respective components, and to have uneven corrosion resistance. Further, the surface of the corrosion-resistant coating layer is likely to be rough, resulting in poor appearance.
The present invention provides: a liquid composition capable of forming a corrosion-resistant coating layer having excellent appearance and being reduced in variation in thermal conductivity, corrosion resistance and corrosion resistance; a laminate having excellent appearance and little variation in thermal conductivity, corrosion resistance and corrosion resistance; a heat exchanger; and a corrosion-resistant coating film.
Technical scheme for solving technical problem
The present invention has the following technical contents.
[1]A liquid composition comprising: containing a melt viscosity of 1X 10 at 380 DEG C2～1×106A layer forming component of Pa · s tetrafluoroethylene polymer powder and a conductive filler, and a liquid medium, wherein the sum of the proportion of the tetrafluoroethylene polymer and the proportion of the conductive filler in the layer forming component is greater than 75% by mass, and at least a part of the layer forming component is dispersed.
[2] The liquid composition according to [1], wherein the layer-forming component contains the conductive filler in an amount of 10% by mass or more.
[3] The liquid composition according to [1] or [2], wherein the viscosity at 25 ℃ is 50 to 10000 mPas.
[4] The liquid composition according to any one of [1] to [3], wherein the conductive filler is a conductive non-metallic filler.
[5] The liquid composition as described in any one of [1] to [4], wherein the conductive filler is carbon short fiber, carbon black, graphene oxide, fullerene, graphite, or graphite oxide.
[6] The liquid composition as described in any one of [1] to [5], wherein the conductive filler is a fibrous conductive filler having an average fiber length of 0.01 to 500 μm or a particulate conductive filler having an average particle diameter of 0.01 to 300 μm.
[7] The liquid composition according to any one of [1] to [6], wherein the tetrafluoroethylene polymer has a melting temperature of 240 ℃ or more and less than 330 ℃.
[8] The liquid composition according to any one of [1] to [7], wherein the tetrafluoroethylene polymer has an average particle diameter of 0.01 to 5.0 μm.
[9] A laminate comprising a substrate and a corrosion-resistant coating layer on the substrate, wherein the corrosion-resistant coating layer comprises a fired product of a layer-forming component in the liquid composition according to any one of [1] to [8 ].
[10]Such as [9]]The laminate according to (1), wherein the corrosion-resistant coating layer has a volume resistivity of 1X 1010Omega cm or less.
[11] The laminate according to [9] or [10], wherein the corrosion-resistant coating layer has a coefficient of thermal expansion of 150 ppm/DEG C or less.
[12] The laminate according to any one of [9] to [11], wherein the corrosion-resistant coating layer has a thickness of20 to 1000 μm or more.
[13] The laminate according to any one of [9] to [12], wherein the base material is metal, glass, or ceramic.
[14] A heat exchanger comprising the heat transfer tube of the laminate according to any one of [9] to [13 ].
[15] A method for producing a corrosion-resistant coating film, comprising removing the base material of the laminate according to any one of [9] to [13] to obtain a corrosion-resistant coating film containing the fired product.
Effects of the invention
According to the liquid composition of the present invention, a corrosion-resistant coating layer having excellent appearance with little variation in thermal conductivity, corrosion resistance and corrosion resistance can be formed.
The laminate of the present invention includes a corrosion-resistant coating layer having excellent appearance and having little variation in thermal conductivity, corrosion resistance, and corrosion resistance.
The heat exchanger of the present invention comprises: the heat transfer tube is a heat transfer tube comprising the laminated body of the present invention having a corrosion-resistant coating layer which has excellent appearance and is less in variation in thermal conductivity, corrosion resistance and corrosion resistance.
Drawings
Fig. 1 is a cross-sectional view showing an example of a heat transfer pipe of a laminate according to the present invention.
Detailed Description
The following terms have the following meanings.
The "average particle diameter of the powder" is a volume-based cumulative 50% diameter of the powder (D50) determined by a laser diffraction scattering method. That is, the particle size distribution of the powder was measured by a laser diffraction scattering method, and a cumulative curve was obtained with the total volume of the particle group as 100%, and the particle size at a point where the cumulative volume reached 50% on the cumulative curve. In addition, the cumulative 90% diameter on a volume basis of the powder is denoted as D90 of the powder.
The "average particle diameter of the conductive filler" is a value obtained by image analysis of the conductive filler using a microscope.
Specifically, 5mL of liquid paraffin for a grade 1 reagent was measured by a dropper in a 30mL Erlenmeyer flask. And collecting a sample of the conductive filler by using a miniature scraper, and dispersing the sample in liquid paraffin. A micropipette was used to measure 300. mu.L of the dispersion from the flask, and the dispersion was dropped on the 1 st glass slide, and the 2 nd glass slide was covered and pressure-bonded. An image of the sample sandwiched between the slides was taken with a CCD MICROSCOPE (for example, scopaman DIGITAL CCD microsoft MS-804 manufactured by MORITEX CORPORATION), and particle diameters were determined for 1000 to 1300 conductive filler particles using image analysis software (for example, WinROOF2015 manufactured by sanko CORPORATION), and the average value was used as the average particle diameter of the conductive filler. If the conductive filler is fibrous, it is the average fiber length of the conductive filler.
When the conductive filler has a nano-size fiber length like a carbon nanotube or a nano-size particle diameter like carbon black and the particle diameter cannot be obtained by a CCD microscope, the particle diameters of 300 conductive filler particles are randomly obtained from an electron micrograph of the conductive filler, and the average value thereof is defined as the average particle diameter or the average fiber length of the conductive filler.
"melt viscosity of polymer" means a value measured by holding a polymer sample (2g) preheated at a measurement temperature for 5 minutes under a load of 0.7MPa at the measurement temperature using a flow tester and a 2. phi. -8L mold based on ASTM D1238.
"melting temperature of a polymer" means a temperature corresponding to the maximum value of a melting peak measured by Differential Scanning Calorimetry (DSC).
The "viscosity of the liquid composition" is a value measured by a B-type viscometer at a temperature of 25 ℃ and a rotation speed of 6 rpm.
The "heat-resistant resin" refers to a polymer compound having a melting temperature of 280 ℃ or higher, or JISC 4003: 2010(IEC 60085: 2007) wherein the maximum continuous use temperature is 121 ℃ or higher.
For convenience of explanation, the size ratio in fig. 1 is different from the actual size ratio.
The "unit" in the polymer may be a radical formed directly from 1 molecule of a monomer by polymerization, or may be a radical in which a part of the structure is converted by treating a polymer obtained by polymerization in a predetermined method. The units based on monomer A contained in the polymer are also referred to simply as "units A".
"(meth) acrylate" is a generic term for both acrylates and methacrylates.
The liquid composition of the present invention comprises: comprises at 380 deg.CMelt viscosity of 1X 102～1×106A powder of a Pa · s tetrafluoroethylene polymer (hereinafter also referred to as a "TFE-based polymer") (hereinafter also referred to as an "F powder") and a layer-forming component of a conductive filler, and a liquid medium. In the layer forming component, the sum of the proportion of the TFE polymer and the proportion of the conductive filler is more than 75% by mass, and at least a part (F powder and the like) of the layer forming component is dispersed in a particulate form.
The liquid composition of the present invention may further contain a material other than the liquid medium, the powder, and the conductive filler (hereinafter referred to as "other material") within a range not to impair the effects of the present invention. Specific examples of other materials are described below. When the other material is a layer-forming component, the other material accounts for less than 25 mass%, preferably 10 mass% or less of the layer-forming component.
The viscosity of the liquid composition of the present invention is preferably 50 to 10000 mPas, more preferably 70 to 5000 mPas, and still more preferably 100 to 5000 mPas. In this range, the liquid composition is more excellent in dispersibility and coatability, and the layer formed therefrom is more likely to have more excellent physical properties.
The liquid medium in the present invention is a dispersion medium in the liquid composition, and is an inert component which is liquid at 25 ℃.
The liquid medium is preferably a compound having a boiling point lower than that of the components other than the liquid medium contained in the liquid composition and being capable of being removed by volatilization by heating or the like.
Examples of the liquid medium include: water, alcohols (methanol, ethanol, propanol, etc.), nitrogen-containing compounds (N, N-dimethylformamide, N-dimethylacetamide, N-methyl-2-pyrrolidone, etc.), sulfur-containing compounds (dimethyl sulfoxide, etc.), alkanes (cyclohexane, etc.), ethers (diethyl ether, dioxane, etc.), esters (ethyl lactate, ethyl acetate, etc.), ketones (methyl ethyl ketone, methyl isopropyl ketone, cyclopentanone, cyclohexanone, etc.), glycol ethers (ethylene glycol monoisopropyl ether, etc.), cellosolves (methyl cellosolve, ethyl cellosolve, etc.), aromatic hydrocarbons, and the like. The liquid medium can be used alone 1, also can be more than 2 combination use.
The boiling point of the liquid medium is preferably 80 to 275 ℃, and particularly preferably 125 to 250 ℃. In this range, when the liquid medium is removed from the liquid composition by heating, the liquid medium does not instantaneously volatilize, and the volatilization of the liquid medium and the uniform layer formation due to the flow of the layer forming component easily proceed in cooperation.
As the liquid medium, alcohols, esters, ketones and amides are preferable, and 2-propanol (boiling point: 82 ℃ C.), 1-propanol (boiling point: 97 ℃ C.), 1-butanol (boiling point: 117 ℃ C.), 1-methoxy-2-propanol (boiling point: 119 ℃ C.), N-methyl-2-pyrrolidone (boiling point: 202 ℃ C.), γ -butyrolactone (boiling point: 204 ℃ C.), cyclohexanone (boiling point: 156 ℃ C.), and cyclopentanone (boiling point: 131 ℃ C.) are more preferable, and N-methyl-2-pyrrolidone, γ -butyrolactone, cyclohexanone, and cyclopentanone are particularly preferable.
The F powder in the present invention is a powder of a TFE polymer.
The F powder may contain components other than the TFE-based polymer within a range not impairing the effect of the present invention, but is preferably composed of only the TFE-based polymer. The F powder may contain 2 or more TFE-based polymers. The proportion of the TFE polymer in the F powder is preferably 80% by mass or more, particularly preferably 100% by mass.
D50 as the F powder is preferably 0.01 to 5.0. mu.m, more preferably 0.1 to 4.0. mu.m, and particularly preferably 0.5 to 3.0. mu.m. In this range, the flowability and dispersibility of the F powder are good. As a result, the corrosion-resistant coating layer has less variation in corrosion resistance, and the appearance of the corrosion-resistant coating layer is improved.
D90 as the F powder is preferably 0.05 to 10 μm, more preferably 0.5 to 8 μm, and particularly preferably 1 to 6 μm. In this range, the F powder is excellent in fluidity and dispersibility, the variation in corrosion resistance in the corrosion-resistant coating layer is further reduced, and the appearance of the corrosion-resistant coating layer is further improved.
The sparse packing volume density of the F powder is preferably 0.08-0.5 g/mL, and the dense packing volume density of the F powder is preferably 0.1-0.8 g/mL.
Examples of the powder F include the powders described in paragraphs [0065] to [0069] of International publication No. 2016/017801. If the desired powder is commercially available, it can be used as an F powder.
The TFE-based polymer in the present invention is a polymer having a Tetrafluoroethylene (TFE) based unit (TFE unit). The TFE-based polymer may be a homopolymer of TFE, or a copolymer of TFE and another monomer copolymerizable with TFE (hereinafter, also referred to as a comonomer). The TFE polymer is preferably a TFE polymer having a ratio of a TFE unit to all units constituting the polymer of 90 to 100 mol%.
Examples of the TFE-based polymer include Polytetrafluoroethylene (PTFE), a copolymer of TFE and ethylene (ETFE), a copolymer of TFE and propylene, a copolymer of TFE and perfluoro (alkyl vinyl ether) (PFA), a copolymer of TFE and hexafluoropropylene (FEP), and a copolymer of TFE and chlorotrifluoroethylene.
The TFE polymer in the present invention has a melt viscosity of 1X 10 at 380 ℃2～1×106Pa · s. The TFE polymer preferably has a melt viscosity of 1X 10 at 340 DEG C2～1×106Pa · s, particularly preferably a melt viscosity at 300 ℃ of 1X 102～1×106Pa · s. In this range, the F powder easily forms a corrosion-resistant coating layer having close packing and high homogeneity and smoothness. As a result, the corrosion-resistant coating layer having less variation in corrosion resistance and good appearance can be formed.
A preferable embodiment of the TFE polymer is low molecular weight PTFE. Low molecular weight PTFE has a melt viscosity of 1X 10 at 380 ℃ as a whole2～1×106Pa · s PTFE may also be PTFE in which only the shell portion of the core-shell structure composed of the core portion and the shell portion satisfies the melt viscosity.
The low molecular weight PTFE may be a high molecular weight PTFE (melt viscosity: 1X 10)9～1×1010Pa · s or so. ) PTFE obtained by irradiation with radiation (see international publication No. 2018/026012, international publication No. 2018/026017, and the like). ) Further, PTFE obtained by reducing the molecular weight of PTFE by using a chain transfer agent in the production of PTFE by polymerizing TFE (see Japanese patent application laid-open No. 2009-1745, International publicationPublication No. 2010/114033, etc. ).
The low-molecular-weight PTFE may be a polymer obtained by polymerizing TFE alone or a copolymer obtained by copolymerizing TFE with a comonomer (see international publication No. 2009/20187, etc.). The proportion of the TFE unit is preferably 99.5 mol% or more, more preferably 99.8 mol% or more, and particularly preferably 99.9 mol% or more, relative to all units constituting the polymer. As the comonomer, a fluorine monomer described later is exemplified, and Hexafluoropropylene (HFP), perfluoro (alkyl vinyl ether) (PAVE) and fluoroalkyl vinyl (FAE) are preferable.
Examples of the PTFE having a core-shell structure include PTFE described in Japanese patent application laid-open No. 2005-527652 and International publication No. 2016/170918. In order to make the melt viscosity of the shell portion fall within the above range, there are a method of reducing the molecular weight of the shell portion with a chain transfer agent (see Japanese patent laid-open No. 2015-232082, etc.), a method of copolymerizing TFE and the above-mentioned comonomer at the time of producing the shell portion (see Japanese patent laid-open No. 09-087334, etc.), and the like.
The Standard Specific Gravity (SSG) of the low molecular weight PTFE is preferably 2.14 to 2.22, more preferably 2.16 to 2.20. SSG can be measured according to ASTM D4895-04.
Other suitable forms of the TFE-based polymer include: a copolymer obtained from TFE and a comonomer, and a hot-melt fluoropolymer in which the proportion of comonomer-based units to all units constituting the copolymer is more than 0.5 mol% (hereinafter also referred to as "polymer F"). The melting temperature of the polymer F is preferably 240 ℃ or higher and less than 330 ℃, more preferably 260 to 320 ℃, and particularly preferably 295 to 310 ℃. In this range, the heat resistance and melt moldability of the polymer F are balanced.
The TFE-based polymer preferably has at least 1 functional group (hereinafter, also referred to as "functional group") selected from a carbonyl group-containing group, a hydroxyl group, an epoxy group, an amide group, an amino group, and an isocyanate group, from the viewpoint of excellent adhesiveness. The functional group can be imparted by plasma treatment or the like.
The functional group may be contained in a unit constituting the TFE-based polymer or may be contained in a terminal group of the main chain of the polymer. The latter polymer may be a polymer having a functional group as an end group derived from a polymerization initiator, a chain transfer agent, or the like.
As the polymer F, a polymer containing a unit having a functional group and a TFE unit is preferable. In this case, the polymer F preferably further has another unit.
The functional group is preferably a carbonyl group-containing group from the viewpoint of adhesiveness. Examples of the carbonyl group-containing group include a carbonate group, a carboxyl group, a haloformyl group, an alkoxycarbonyl group, an acid anhydride residue, and a fatty acid residue, and a carboxyl group and an acid anhydride residue are preferable.
As the unit having a functional group, a unit based on a monomer having a functional group is preferable, a unit based on a monomer having a carbonyl group, a unit based on a monomer having a hydroxyl group, a unit based on a monomer having an epoxy group, and a unit based on a monomer having an isocyanate group are more preferable, and a unit based on a monomer having a carbonyl group is particularly preferable.
As the monomer having a carbonyl group, a cyclic monomer having an acid anhydride residue, a monomer having a carboxyl group, a vinyl ester and a (meth) acrylic ester are preferable, and a cyclic monomer having an acid anhydride residue is particularly preferable.
As the cyclic monomer having an acid anhydride residue, itaconic anhydride, citraconic anhydride, 5-norbornene-2, 3-dicarboxylic anhydride (also referred to as nadic anhydride, hereinafter, also referred to as "NAH") and maleic anhydride are preferable.
As the unit having a functional group and the unit other than the TFE unit, an HFP unit, a PAVE unit, and a FAE unit are preferable.
As PAVE, CF is mentioned2＝CFOCF3、CF2＝CFOCF2CF3、CF2＝CFOCF2CF2CF3(PPVE)、CF2＝CFOCF2CF2CF2CF3、CF2＝CFO(CF2)8F, etc., preferably PAVE.
As FAE, CH may be mentioned2＝CH(CF2)2F、CH2＝CH(CF2)3F、CH2＝CH(CF2)4F、CH2＝CF(CF2)3H、CH2＝CF(CF2)4H, etc., preferably CH2＝CH(CF2)4F and CH2＝CH(CF2)2F。
As the polymer F, a polymer containing a unit having a functional group, a TFE unit, a PAVE unit, or an HFP unit is preferable. Specific examples of the polymer F include the polymer (X) described in International publication No. 2018/16644.
The proportion of TFE units in the polymer F is preferably 90 to 99 mol% among all units constituting the polymer F.
The proportion of the PAVE unit or HFP unit in the polymer F is preferably 0.5 to 9.97 mol% in all units constituting the polymer F.
The proportion of the unit having a functional group in the polymer F is preferably 0.01 to 3 mol% of all units constituting the polymer F.
The conductive filler in the present invention is preferably selected from conductive fillers for resins.
Examples of the conductive filler include: a carbon-containing filler, a metal powder, a conductive metal oxide (conductive titanium oxide, conductive tin oxide, conductive mica, etc.), and an ionic conductive agent. As the conductive filler, a conductive non-metallic filler is preferable, and a carbonaceous filler is particularly preferable, from the viewpoint of excellent corrosion resistance.
The carbonaceous filler is preferably short carbon fibers, carbon black, graphene oxide, fullerene, graphite, and graphite oxide, and particularly preferably short carbon fibers, carbon black, and graphite, from the viewpoint of excellent thermal conductivity.
The carbonaceous filler may be surface-treated with subcritical water or supercritical water at a pressure of 50 to 400atm and a temperature of 100 to 600 ℃ in the absence of an oxidizing agent.
Examples of the carbon short fibers include: short carbon fibers obtained by cutting or pulverizing carbon fibers (such as PAN-based carbon fibers and pitch-based carbon fibers), vapor grown carbon fibers, and carbon nanotubes (single-layer, double-layer, multi-layer, cup-stacked).
Examples of carbon black include: furnace black, acetylene black, thermal black, channel black, and the like.
When the conductive filler is fibrous, the conductive filler has an average fiber length of preferably 0.01 to 500. mu.m, more preferably 1 to 300. mu.m, still more preferably 3 to 200. mu.m, and particularly preferably 5 to 100. mu.m. In this range, the dispersibility of the conductive filler is excellent. As a result, the corrosion-resistant coating layer having less variation in thermal conductivity is easily formed.
When the conductive filler is in the form of particles, the average particle diameter of the conductive filler is preferably 0.01 to 30 μm, more preferably 0.03 to 10 μm, and particularly preferably 0.05 to 1 μm. In this range, the dispersibility of the conductive filler is excellent. As a result, the corrosion-resistant coating layer having less variation in thermal conductivity is easily formed.
The conductive filler is preferably 0.01 to 500 μm in average fiber length in the case of short carbon fibers, 0.01 to 0.5 μm in average particle diameter in the case of carbon black, and 1 to 300 μm in average particle diameter in the case of graphite.
The liquid composition of the present invention preferably contains a surfactant from the viewpoint of promoting dispersion of the layer forming component and further improving the physical properties of the layer formed therefrom. The surfactant may be used alone in 1 kind, or may be used in combination of2 or more kinds.
The surfactant is preferably a nonionic surfactant.
When the liquid composition contains a dispersant, the proportion thereof is preferably 1 to 20% by mass, and particularly preferably 3 to 10% by mass. In this range, a corrosion-resistant coating layer having high homogeneity and smoothness can be easily formed.
As the surfactant, a fluorine-based surfactant having a fluorine-containing group and a hydrophilic group is preferable. When a fluorine-based surfactant is used, the surface tension of the liquid medium is reduced, the wettability to the surface of the F powder is improved, and the dispersibility of the F powder is improved, and at the same time, a fluorine-containing group is adsorbed on the surface of the TFE-based polymer powder (F powder), and a hydrophilic group is extended in the liquid medium, whereby the aggregation of the F powder is prevented by the steric hindrance of the hydrophilic group, and the dispersion stability is further improved.
The fluorine-containing group is preferably a perfluoroalkyl group or a perfluoroalkenyl group. The number of carbons of the fluorine-containing group is preferably 4 to 12.
The hydrophilic group is preferably an alcoholic hydroxyl group or a polyoxyalkylene group.
Examples of the fluorine-based surfactant include: FTERGENT (M series, F series, G series, P.D series, 710FL, 710FM, 710FS, 730FL, 730LM, 610FM, 601AD, 601ADH2, 602A, 650AC, 681) available from Bell corporation, SURFON series (S-386, etc.) available from AGC cleaning and beauty chemical Co., Ltd, MEGAFACE series (F-553, F-555, F-556, F-557, F-559, F-562, F-565, etc.) available from DIC corporation, and UNIDYNE series (DS-403N, etc.) available from Dajin Industrial Co., Ltd.
Examples of the other material include resin materials other than TFE-based polymers. The resin material may be soluble in the liquid composition or may be insoluble in the liquid composition.
The resin material may be a non-curable resin or a curable resin.
Examples of the non-curable resin include a hot-melt resin and a non-melt resin. Examples of the hot-melt resin include thermoplastic polyimide. Examples of the non-fusible resin include cured products of curable resins.
Examples of the curable resin include epoxy resins, thermosetting polyimides, polyamide acids which are precursors of polyimides, thermosetting acrylic resins, phenol resins, thermosetting polyester resins, thermosetting polyolefin resins, thermosetting modified polyphenylene ether resins, polyfunctional cyanate resins, polyfunctional maleimide-cyanate resins, polyfunctional maleimide resins, vinyl ester resins, urea resins, diallyl phthalate resins, melamine resins, guanamine resins, and melamine-urea copolymer resins. Among them, from the viewpoint of being usable for printed board applications, thermosetting polyimide, polyimide precursor, epoxy resin, thermosetting acrylic resin, bismaleimide resin, and thermosetting polyphenylene ether resin are preferable as the thermosetting resin, and epoxy resin and thermosetting polyphenylene ether resin are particularly preferable.
Specific examples of the epoxy resin include naphthalene type epoxy resins, cresol novolac type epoxy resins, bisphenol a type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, alicyclic epoxy resins, aliphatic chain epoxy resins, cresol novolac type epoxy resins, phenol novolac type epoxy resins, alkylphenol novolac type epoxy resins, aralkyl type epoxy resins, bisphenol type epoxy resins, dicyclopentadiene type epoxy resins, trishydroxyphenylmethane type epoxy compounds, epoxy compounds of condensates of phenol and aromatic aldehydes having a phenolic hydroxyl group, diglycidyl etherate of bisphenol, diglycidyl etherate of naphthalene diol, glycidyl etherate of phenol, diglycidyl etherate of alcohol, triglycidyl isocyanurate, and the like.
Examples of the bismaleimide resin include a resin composition (BT resin) obtained by using a bisphenol a type cyanate resin and a bismaleimide compound in combination as disclosed in japanese patent laid-open No. 7-70315, an invention disclosed in international publication No. 2013/008667, and a resin disclosed in the background art thereof.
The polyamic acid generally has a reactive group capable of reacting with the functional group of the TFE-type polymer.
Examples of the diamine and polycarboxylic acid dianhydride that form the polyamic acid include diamines and polycarboxylic acid dianhydrides described in [0020] of Japanese patent No. 5766125, [0019] of Japanese patent No. 5766125, and [0055] and [0057] of Japanese patent laid-open Nos. 2012 and 145676. Among these, polyamic acids obtained by combining aromatic diamines such as 4,4 ' -diaminodiphenyl ether and 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane with aromatic polybasic acid dianhydrides such as pyromellitic dianhydride, 3 ', 4,4 ' -biphenyltetracarboxylic dianhydride and 3,3 ', 4,4 ' -benzophenonetetracarboxylic dianhydride are preferred.
Examples of the hot-melt resin include thermoplastic resins such as thermoplastic polyimides and hot-melt cured products of curable resins.
Examples of the thermoplastic resin include polyester resins, polyolefin resins, styrene resins, polycarbonates, thermoplastic polyimides, polyarylates, polysulfones, polyarylsulfones, aromatic polyamides, aromatic polyetheramides, polyphenylene sulfides, polyaryletherketones, polyamideimides, liquid crystalline polyesters, polyphenylene ethers, and the like, and thermoplastic polyimides, liquid crystalline polyesters, and polyphenylene ethers are preferred.
Further, as other materials, there can be also mentioned: thixotropy imparting agents, antifoaming agents, inorganic fillers (excluding conductive fillers), reactive alkoxysilanes, dehydrating agents, plasticizers, weather-resistant agents, antioxidants, heat stabilizers, lubricants, antistatic agents, whitening agents, colorants, conductive agents, mold release agents, surface treatment agents, viscosity modifiers, flame retardants.
The layer forming component of the present invention contains a TFE-based polymer and a conductive filler, and may contain other layer forming components (a layer forming material among the above materials, etc.) within a range not impairing the effects of the present invention. The sum of the proportion of the TFE polymer in the layer-forming component and the proportion of the conductive filler is greater than 75% by mass, preferably 90% by mass or more. The upper limit of the sum is 100 mass%.
The ratio of the conductive filler in the layer forming component is preferably 10 mass% or more, more preferably 35 mass% or more, and particularly preferably 45 mass% or more. The upper limit of the proportion is usually 80 mass%.
When the sum and the ratio to the conductive filler are within the above ranges, a corrosion-resistant coating layer having a balanced thermal conductivity and corrosion resistance can be more easily formed.
The total content of the TFE polymer and the conductive filler in the liquid composition of the present invention is preferably 10 to 80% by mass, and particularly preferably 30 to 70% by mass. In this range, the liquid composition has excellent coatability, and the corrosion-resistant coating layer is less likely to have poor appearance.
The mass ratio of the TFE polymer to the conductive filler (F powder/conductive filler) in the liquid composition is preferably 90/10 to 5/85, more preferably 80/20 to 20/80. In this range, a corrosion-resistant coating layer having an excellent balance between thermal conductivity and corrosion resistance can be easily formed.
When the conductive filler is carbon short fibers, the mass ratio of the F powder to the carbon short fibers (F powder/carbon short fibers) in the liquid composition is preferably 90/10 to 10/90, and more preferably 80/20 to 20/80. In this range, the coating film can exhibit the advantages derived from the carbon fibers, and can be smoothly coated, so that the coating film has excellent coatability, and can simultaneously realize the advantages of the TFE-based polymer and the advantages derived from the carbon fibers, and the coating film has excellent adhesion strength to the substrate.
The liquid composition of the present invention described above contains an electrically conductive filler, and therefore can form a corrosion-resistant coating layer having thermal conductivity.
When the liquid composition of the present invention is used, a corrosion-resistant coating layer having corrosion resistance can be formed.
That is, in the liquid composition of the present invention, the melt viscosity at 380 ℃ is 1X 102～1×106The Pa · s TFE-based polymer and the conductive filler are main layer-forming components, and the former component is highly dispersed as F powder. When the layer is formed from the liquid composition, the F powder is densely packed, and a coating layer having high dispersibility of the conductive filler and high homogeneity and smoothness is easily formed. As a result, it is considered that the corrosion-resistant coating layer having a good appearance with less variation in corrosion resistance is formed by these synergistic effects.
When the liquid composition of the present invention is applied to a substrate, and the liquid medium is removed and then fired, a laminate having a corrosion-resistant coating layer composed of the substrate and a fired product of the layer forming components on the substrate can be obtained. The coating, the removal of the liquid medium, and the firing may be performed in the same manner as in the heat transfer pipe described below.
As the material of the substrate, metal, glass, and ceramic are preferable, and metal is particularly preferable.
Examples of the metal include copper, copper alloy, aluminum alloy, iron alloy, and brass.
Examples of the glass include soda lime glass, soda potassium glass, soda aluminosilicate glass, aluminum borate glass, aluminum borosilicate glass, low expansion glass, quartz glass, and porous glass.
Examples of the ceramics include alumina, zirconia, mullite, cordierite, talc, magnesium titanate, calcium titanate, strontium titanate, aluminum nitride, silicon carbide, and silicon nitride.
The shape of the substrate is not particularly limited, and examples thereof include a flat plate shape, a tubular shape, a spherical shape, a curved surface shape, a wedge shape, and a wave shape.
As a preferred example of the substrate, a main body of a heat transfer pipe described later can be mentioned. A corrosion-resistant coating layer is formed on the outer surface of a tubular base material composed of a tube, a finned tube, or the like, thereby making it possible to provide a heat transfer tube for use in a heat exchanger or the like.
Further, since thermal conductivity and electrical conductivity are correlated, the thermal conductivity of the corrosion-resistant coating layer can be evaluated by volume resistivity. It can be said that the higher the volume resistivity, the lower the thermal conductivity, and the lower the volume resistivity, the higher the thermal conductivity. The volume resistivity of TFE polymers is usually 1X 1017Omega cm or more, and its thermal conductivity is also very low.
Since the liquid composition of the present invention contains a TFE-based polymer and a conductive filler, the conductivity of the layer (corrosion-resistant coating layer) formed therefrom is improved, and the volume resistivity thereof can be easily adjusted to 1 × 1010Omega cm or less, so that the corrosion-resistant coating layer has good thermal conductivity. The volume resistivity of the corrosion-resistant coating layer is preferably 1X 109Not more than Ω cm, more preferably 1X 108Not more than Ω cm, particularly preferably 1X 106Omega cm or less. If the amount exceeds the upper limit, thermal and electrical conductivity deteriorates, and the heat transfer efficiency of the heat exchanger deteriorates.
The linear expansion coefficient of the corrosion-resistant coating layer is preferably 150 ppm/DEG C or less, more preferably 130 ppm/DEG C or less, and preferably 100 ppm/DEG C or less. If the content is not more than the upper limit, the adhesion strength between the base material and the corrosion-resistant coating layer can be maintained high even in a high-temperature environment. The corrosion-resistant coating layer most preferably has substantially the same linear expansion coefficient as the substrate.
The thickness of the corrosion-resistant coating layer is preferably 2 μm or more, more preferably 10 μm or more, and particularly preferably 20 μm or more. The thickness of the corrosion-resistant coating layer is preferably 1000 μm or less, more preferably 500 μm or less, and particularly preferably 200 μm or less. In this range, the corrosion-resistant coating layer is more likely to have a balance between the thermal conductivity and the corrosion resistance.
Further, when the substrate is removed from the laminate of the present invention, a corrosion-resistant coating film can be obtained. Examples of the method for removing the substrate include a method for peeling the substrate from the laminate and a method for dissolving the substrate from the laminate. For example, when the substrate of the laminate is a copper foil, the substrate is dissolved and removed when the substrate surface of the laminate is brought into contact with an etching solution such as hydrochloric acid.
A preferred example of the laminate of the present invention is a heat transfer pipe.
The heat transfer pipe which is a laminate of the present invention has a corrosion-resistant coating layer on the outer surface of a tubular base material, the corrosion-resistant coating layer being obtained by applying the liquid composition of the present invention to the outer surface of the tubular base material, removing the liquid medium, and then firing the composition.
Fig. 1 is a cross-sectional view showing an example of the heat transfer pipe.
The heat transfer pipe 10 has a pipe-shaped base material composed of a pipe 12 and fins 14 provided on the outer periphery of the pipe 12, and a corrosion-resistant coating layer 16 covering the outer surface of the pipe 12 and the surfaces of the fins 14.
Examples of the material of the tube 12 include the above-mentioned metals, and copper, copper alloys, aluminum, and aluminum alloys are preferable from the viewpoint of thermal conductivity.
The outer diameter and the inner diameter of the tube 12 can be set as appropriate depending on the material of the tube, the application of the heat transfer pipe, and the like.
The material of the fin 14 may be, for example, the above-mentioned metal, and copper, a copper alloy, aluminum, and an aluminum alloy are preferable from the viewpoint of thermal conductivity. The fins are generally of the same material as the tubes.
The number, shape, thickness, area, and arrangement pitch of the fins can be appropriately set according to the material of the fins, the use of the heat transfer pipe, and the like. Examples of the shape of the fin include plate fins, brass plate fins (japanese: ブレージングプレートフィン), corrugated fins, slit fins, helical fins, mesh fins (japanese: メッシュフィン), tube fins, and air fins.
The thickness of the corrosion-resistant coating layer is preferably 2 to 500. mu.m, and particularly preferably 10 to 200. mu.m. In this range, the corrosion-resistant coating layer has an excellent balance between thermal conductivity and corrosion resistance.
For example, a heat transfer pipe is produced by applying the liquid composition of the present invention to the outer surface of a tubular base material, removing the liquid medium, and then firing the composition to form a corrosion-resistant coating layer. Examples of the shape of the heat transfer pipe include plate-fin type heat transfer pipes, brass-plate type (japanese patent publication No. ブレージングプレート type) heat transfer pipes, plate-fin type heat transfer pipes, spiral-fin type heat transfer pipes, double-pipe type heat transfer pipes, cross-fin type heat transfer pipes, corrugated fin type heat transfer pipes, slit fin type heat transfer pipes, net fin type (japanese patent publication No. メッシュフィン type) heat transfer pipes, tube fin type heat transfer pipes, and air fin type heat transfer pipes, and specific examples thereof include those described in the drawings of japanese patent publication No. 59-38517, japanese patent application laid-open No. 60-141437, and japanese patent application laid-open No. 63-54984.
Examples of the coating method include: spray coating, roll coating, spin coating, gravure coating, microgravure coating, gravure offset coating, knife coating, kiss roll coating (japanese: キスコート method), bar coating, die coating, jet meyer bar coating (japanese: ファウンテンメイヤーバー method), slit die coating.
Preferably, after application of the liquid composition, the liquid medium is removed while maintaining the temperature in the low temperature range. The temperature in the low temperature range is preferably 80 ℃ or higher and less than 180 ℃, more preferably 100 to 175 ℃, and particularly preferably 120 to 170 ℃. The temperature at which the temperature is maintained in the low temperature range indicates the temperature of the atmosphere. The low temperature range can be maintained in one step or in more than two steps at different temperatures. Examples of the heating method in the low temperature range include: a method using an oven, a method using a forced air drying oven, and a method of irradiating heat rays such as infrared rays.
The atmosphere in the low temperature range may be either normal pressure or reduced pressure. The atmosphere in the low temperature range may be any of an oxidizing gas (oxygen, etc.) atmosphere, a reducing gas (hydrogen, etc.) atmosphere, and an inert gas (helium, neon, argon, nitrogen, etc.) atmosphere.
The time for holding in the low temperature range is preferably 0.1 to 10 minutes, and particularly preferably 0.5 to 5 minutes.
It is preferable to maintain the temperature range in which the TFE polymer is fired (hereinafter also referred to as "firing range") after the liquid medium is removed. The temperature of the firing range indicates the temperature of the atmosphere. The firing range is a temperature range of the holding temperature higher than the low temperature range.
The firing method may, for example, be a method using an oven, a method using a through-air drying oven, or a method of irradiating heat rays such as infrared rays. In order to improve the smoothness of the surface of the corrosion-resistant coating layer, pressurization may be performed using a hot plate, a hot roller, or the like. As the firing method, a method of irradiating far infrared rays is preferable from the viewpoint that firing can be performed in a short time and the far infrared furnace is relatively compact. A combination of infrared heating and hot air heating is possible. From the viewpoint of promoting homogeneous fusion of TFE polymers, the effective wavelength band of far infrared rays is preferably 2 to 20 μm, and particularly preferably 3 to 7 μm.
The firing temperature is preferably 250 to 400 ℃ or lower, and particularly preferably 300 to 380 ℃.
The time for holding in the firing range is preferably 30 seconds to 10 minutes, and particularly preferably 1 to 5 minutes.
The atmosphere during firing may be either normal pressure or reduced pressure. The atmosphere during firing may be any of an oxidizing gas (oxygen, etc.) atmosphere, a reducing gas (hydrogen, etc.) atmosphere, and an inert gas (helium, neon, argon, nitrogen, etc.) atmosphere, and a reducing gas atmosphere or an inert gas atmosphere is preferable from the viewpoint of suppressing oxidative deterioration of the tubular base material and the corrosion-resistant coating layer.
The atmosphere during firing is preferably a gas atmosphere containing an inert gas and having a low oxygen concentration, and is preferably a gas atmosphere containing nitrogen and having an oxygen concentration (based on volume) of less than 500 ppm. The oxygen concentration (based on volume) is particularly preferably 300ppm or less. The oxygen concentration (volume basis) is usually 1ppm or more.
The heat exchanger of the present invention includes the heat transfer pipe which is the laminate of the present invention.
In the heat exchanger of the present invention, the heat transfer pipe is preferably provided at a position where sulfuric acid is generated when the combustion gas containing moisture and sulfur compounds is cooled to a temperature not higher than the dew point temperature of sulfuric acid.
For example, the heat exchanger of the present invention is used as an economizer in a boiler.
The liquid composition of the present invention is useful as a heat-releasing and heat-conducting resin material and a heat-conducting film-forming material, particularly as the latter material, in various fields such as the electric and electronic industry field and the automobile field.
The heat transfer tube which is a laminated body of the present invention can be used for applications requiring corrosion resistance of the heat exchanger or the fins or tubes constituting the heat exchanger. For example, there are cases where a facility which burns a sulfur-containing partial fuel to generate exhaust gas (for example, a thermal power plant which is a combustion facility for a sulfur-containing partial fuel such as coal and heavy oil) is exposed to sulfuric acid, and a stack, an exhaust pipe, and the like for discharging exhaust gas generated during combustion.
The liquid composition of the present invention can also be used as a material for forming a heat conductive film on a heat-emitting member or the like when heat from various heat-emitting members is released.
Examples of the heat generating member include a power device, a transistor, a thyristor, a rectifier, a transformer, a power MOS FET, a CPU, and the like, and examples of the heat generating member include a heat radiating fin and a metal heat radiating plate, more specifically, a frame of a computer and a display, an electronic device material, a sealing material for an interior and exterior package of an automobile, a processing machine and a vacuum furnace which perform a heat treatment under a low oxygen atmosphere, a sealing material for a plasma processing apparatus, and a heat radiating member in a processing unit of a sputtering apparatus, various dry etching apparatuses, and the like.
The present invention can also be used as a material for forming a heat-conductive heat-resistant coating layer by impregnating and drying an insulating layer of a printed wiring board, a heat-conductive interface material, a substrate for a power module, a coil used in a power device such as a motor, and the like.
Further, the liquid composition of the present invention can also be used for applications in which a resin layer is formed by coating the liquid composition on a bearing, a piston, a carrier, a sliding member such as a slide switch or a gear, or a separator of a fuel cell.
In addition, the liquid composition of the present invention can also be used as an adhesive. In semiconductor devices, high-density substrates, module members, and the like, adhesives are used for bonding electronic components such as IC chips, resistors, and capacitors mounted on substrates, bonding circuit substrates and heat-radiating plates, and bonding LED chips to substrates. In the mounting process of the electronic component, it is also preferably used as a conductive bonding material between the circuit wiring and the electronic component (as an application of replacing solder bonding). In addition, the adhesive can also be used for bonding between a ceramic member and a metal member in an in-vehicle engine. In addition, the printed circuit board can be used as a novel printed circuit board material in place of a conventional glass epoxy board in order to prevent a temperature rise of the printed circuit board on which electronic components are densely mounted.
Examples
The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.
The various measurement methods are shown below.
Melt viscosity of the Polymer
The measurement was carried out by holding a polymer sample (2g) preheated at the measurement temperature for 5 minutes at the measurement temperature under a load of 0.7MPa using a flow tester and a 2. phi. -8L mold based on ASTM D1238.
Melting temperature of the polymer
A melting peak of the polymer at a temperature rise of 10 ℃ per minute was recorded by a differential scanning calorimeter (DSC-7020, manufactured by Seiko Seisakusho K.K.), and the temperature corresponding to the maximum value was defined as the melting temperature.
Particle size of the powder
The powder was dispersed in water and measured using a laser diffraction scattering particle size distribution measuring device (horiba, japan), LA-920 measuring device.
(sparse pack bulk density and dense pack bulk density)
The bulk density of the powder at the sparse packing and the bulk density at the dense packing were measured by the methods described in paragraphs [0117] and [0118] of International publication No. 2016/017801.
Viscosity of the liquid composition
The measurement was carried out with a type B viscometer (model LVDV2T, manufactured by Brookfield corporation, Japanese: ブルックフィールド) at a temperature of 25 ℃ and a rotation speed of 6 rpm.
The raw materials used are as follows.
< powder of TFE-based Polymer >
Powder 1: from a polymer 1 having an acid anhydride group and having TFE units, NAH units and PPVE units in the order of 97.9 mol%, 0.1 mol%, 2.0 mol% (melting temperature: 300 ℃ C., melt viscosity at 300 ℃ C. of 103Pa · s) (average particle diameter (D50): 1.7 μm, D90: 3.8 μm. ).
Powder 2: comprising a polymer 2 which is a substantially homopolymer of TFE and has a TFE unit content of 99.5 mol% or more (melting temperature: 330 ℃, melt viscosity at 380 ℃ of more than 1X 10)6Pa · s) (average particle diameter: 7 μm, AGC system "L173J". ).
< liquid Medium >
NMP: n-methyl pyrrolidone.
< dispersant >
Dispersant 1: a (meth) acrylic polymer having a perfluoroalkenyl group, a hydroxyl group and a polyoxyethylene group in each side chain (FTERGENT 710FL available from Bell chemical Co., Ltd.).
< conductive Filler >
Packing 1: carbon short fibers having an average fiber length of 90 μ M (manufactured by wuyu corporation, microfine carbon short fibers (japanese: クレカチョップ), M-2007S.).
Example 1 production of liquid composition
Examples 1-1 preparation of liquid composition 11
102g of powder 1, 10.2g of dispersant 1 and 91.8g of NMP were charged in a horizontal ball mill vessel and dispersed with zirconia balls having a particle diameter of 15 mm. Further, 26g of filler 1 was added and stirred at 500rpm for 5 minutes using a uniform dispersant to obtain a liquid composition 11.
Examples 1-2 to 1-7 production of liquid compositions 12 to 17
Liquid compositions 12 to 17 were obtained in the same manner as in example 1-1, except that the kinds and the proportions of the respective components were changed. The results are shown in the following table 1 together with the evaluation results.
[ Table 1]
Figure BDA0002843568170000191
The dispersibility and coatability of the liquid composition were evaluated by the following methods.
< dispersibility >
In the liquid composition immediately after preparation, the dispersion state of the powder and the conductive filler was visually confirmed, and the evaluation was performed according to the following criteria.
Poor: the aggregates of the powder or the conductive filler can be visually confirmed.
Good: no aggregates of the powder and the conductive filler were observed.
< coatability >
The liquid composition was applied to the surface of a stainless steel substrate using a wire bar (No 14, manufactured by Instrument industries, Ltd.), heated at 100 ℃ for 10 minutes to remove the liquid medium in the liquid composition, and the appearance of the formed coating film (having a thickness of about 200 μm) was visually confirmed and evaluated by the following criteria.
Poor: the coating film is not uniform or has a striped depth.
Good: the coating film is uniform and has little depth.
In the table, the "filler + F polymer ratio" is the sum of the ratio (mass%) of the filler in the layer-forming components of the liquid composition and the ratio (mass%) of the TFE-based polymer, and the "filler ratio" is the ratio (mass%) of the filler in the layer-forming components of the liquid composition.
Example 2 production of laminate
Example 2-1 production example of laminate 11
The liquid composition 11 was applied to the surface of a stainless steel substrate using a wire bar (product of instrumentation industries, Ltd., No 14). The resulting mixture was heated at 100 ℃ for 10 minutes to remove the liquid medium from the liquid composition, thereby obtaining a laminate having a coating film with a thickness of about 200 μm formed on the surface of the substrate. The laminate was heated at 340 ℃ for 15 minutes under a nitrogen atmosphere, and a laminate 11 in which the powder was melted and a corrosion-resistant coating layer was formed on the surface of the substrate was obtained.
[ examples 2-2 to 2-7] production examples of laminates 12 to 17
Laminates 12 to 17 were obtained in the same manner as in example 2-1, except that the liquid composition was changed. The results are shown in Table 2 below together with the evaluation results.
[ Table 2]
Figure BDA0002843568170000201
The appearance and adhesiveness of the laminate were evaluated by the following methods.
< appearance >
Poor: the corrosion-resistant coating layer is uneven in the components or rough in the surface.
Good: the corrosion-resistant coating layer contains a uniform amount of each component and has no rough surface.
< adhesion >
Poor: the corrosion-resistant coating layer is peeled off from the substrate.
Good: the corrosion-resistant coating layer adheres to the substrate and does not peel off.
Example 3 production of liquid composition
Liquid compositions 20 to 29 were obtained in the same manner as in example 1, except that the kinds and the proportions of the respective components were changed. The results are shown collectively in table 3 below. The epoxy resins in the table are commercially available curable compositions for forming an undercoat layer, which contain an aromatic epoxy resin and a curing agent, and the component amounts thereof are amounts as layer forming components.
[ Table 3]
Figure BDA0002843568170000211
Example 4 production of laminate
Example 4-1 production evaluation example of laminate 20
The liquid composition 21 was dip coated onto an aluminum substrate (thickness 2mm, width 40mm, length 150 mm). Then, the liquid medium was removed by heating at 120 ℃ for 10 minutes under an air atmosphere. Next, heating was performed at 340 ℃ for 15 minutes, so that the powder was melted and a corrosion-resistant coating layer was formed on the surface of the base material, to obtain a laminated body 20. The dip coating is adjusted so that the thickness of the corrosion-resistant coating layer 21 is 80 to 120 μm.
[ examples 4-2 to 4-10] production evaluation examples of laminates 21 to 29
Laminates 22 to 30 were obtained in the same manner as in example 4-1, except that the type of the liquid composition was changed. The results are shown in Table 4 below together with the evaluation results.
[ Table 4]
Figure BDA0002843568170000221
The reliability test, linear expansion coefficient and volume resistivity of the laminate were evaluated by the following criteria.
< reliability test >
Powder of polymer 1 was electrostatically coated on the corrosion-resistant coating layer of the laminate, and the laminate was heated at 340 ℃ for 10 minutes to melt the powder, thereby forming a layer (thickness 100 μm) of polymer 1 on the surface of the corrosion-resistant coating layer. The laminate was exposed to a PCT tester (HASTEST MODEL PC-III, HIRAYAMA) at 130 ℃ and 100% RH for 120 hours. The bare core (the part where the layers are not laminated) of the laminate was fixed to a chuck of a tensile tester, and the adhesion of the corrosion-resistant coating layer after PCT was determined as 90 degrees detachable strength at a tensile rate of 50 mm/min.
Grade A … 15N/cm above
B-level … 5 above 5N/cm and less than 15N/cm
The C level … is less than 5N/cm
< coefficient of linear expansion (CTE) >
A sample obtained by cutting a laminate into long strips (width: 4mm, run: 55mm) was dried in an oven at 250 ℃ for 1 hour, and measured by using a thermomechanical analyzer (TMA/SS6100) manufactured by SII. Specifically, the sample was heated from 25 ℃ to 260 ℃ at a rate of2 ℃/min while applying a load of20 mN with a chuck pitch of20 mm in an air atmosphere, and the amount of displacement accompanying the linear expansion of the sample was measured. After the measurement, the amount of displacement is defined as the linear expansion coefficient (ppm/DEG C) at 25 to 260 ℃.
< volume resistivity >
The liquid composition used for the production of the laminate was applied to a film (thickness 50 μm, product of yu ken corporation, trade name "UPILEX S") by a bar coating method, heated at 100 ℃ for 10 minutes, then heated at 340 ℃ for 10 minutes, and a treated film was prepared by another method in which the polymer was melted to form a corrosion-resistant coating layer (thickness 30 μm). A test piece (length: 70mm, width: 10mm) was cut out of the treated film, and the volume resistivity (Ω cm) of the treated film was determined as the volume resistivity of the laminate by the 4-probe method (JIS-7194) using a resistivity meter (Loresta-GP, manufactured by Mitsubishi chemical Co., Ltd.).
< chemical resistance >
The laminate was immersed in a 25% sulfuric acid aqueous solution at 80 ℃ for 24 hours, and then used in the above reliability test to evaluate the adhesiveness of the corrosion-resistant coating layer after PCT.
Possibility of industrial utilization
The liquid composition of the present invention is useful as a coating material for forming a corrosion-resistant coating layer or the like in a heat transfer pipe of a heat exchanger.
In addition, the entire contents of the specification, claims, abstract and drawings of japanese patent application No. 2018-117987 filed on day 21, 06, 2018 and japanese patent application No. 2018-235717 filed on day 17, 12, 2018 are cited herein as disclosures of the description of the present invention.
Description of the symbols
10 heat conduction pipe,
12 tubes,
14 fins,
16 corrosion resistant coating.

Claims (15)

1. A liquid composition comprising: containing a melt viscosity of 1X 10 at 380 DEG C2～1×106A layer forming component of Pa · s tetrafluoroethylene polymer powder and a conductive filler, and a liquid medium, wherein the sum of the proportion of the tetrafluoroethylene polymer and the proportion of the conductive filler in the layer forming component is greater than 75% by mass, and at least a part of the layer forming component is dispersed.
2. The liquid composition according to claim 1, wherein the layer-forming component contains the conductive filler in an amount of 10% by mass or more.
3. The liquid composition according to claim 1 or 2, wherein the viscosity at 25 ℃ is 50 to 10000 mPa-s.
4. A liquid composition as claimed in any one of claims 1 to 3, wherein the electrically conductive filler is an electrically conductive non-metallic filler.
5. A liquid composition according to any one of claims 1 to 4, wherein the electrically conductive filler is carbon staple fibre, carbon black, graphene oxide, fullerene, graphite or graphite oxide.
6. A liquid composition according to any one of claims 1 to 5, wherein the conductive filler is a fibrous conductive filler having an average fiber length of 0.01 to 500 μm or a particulate conductive filler having an average particle diameter of 0.01 to 300 μm.
7. A liquid composition according to any one of claims 1 to 6, wherein the tetrafluoroethylene polymer is a tetrafluoroethylene polymer having a melting temperature of 240 ℃ or higher and less than 330 ℃.
8. The liquid composition as claimed in any one of claims 1 to 7, wherein the average particle diameter of the tetrafluoroethylene polymer is 0.01 to 5.0 μm.
9. A laminate comprising a substrate and a corrosion-resistant coating layer on the substrate, wherein the corrosion-resistant coating layer comprises a fired product of a layer forming component in the liquid composition according to any one of claims 1 to 8.
10. The laminate of claim 9, wherein the corrosion-resistant coating has a volume resistivity of 1 x 1010Omega cm or less.
11. The laminate of claim 9 or 10, wherein the corrosion-resistant coating has a coefficient of thermal expansion of 150ppm/° c or less.
12. The laminate according to any one of claims 9 to 11, wherein the corrosion-resistant coating layer has a thickness of20 to 1000 μm or more.
13. The laminate according to any one of claims 9 to 12, wherein the substrate is made of metal, glass or ceramic.
14. A heat exchanger comprising a heat transfer tube which is the laminate according to any one of claims 9 to 13.
15. A method for producing a corrosion-resistant coating film, characterized by removing the base material of the laminate according to any one of claims 9 to 13 to obtain a corrosion-resistant coating film containing the fired product.
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