JP7363797B2 - Method for producing dispersion liquid and resin-coated metal foil - Google Patents

Description

The present invention relates to a dispersion liquid that suppresses powder falling during layer (resin layer) formation and that can form layers (resin layers) with excellent physical properties in various layers (resin layers), and a method for producing resin-coated metal foil.

Tetrafluoroethylene polymers such as polytetrafluoroethylene (PTFE) have excellent physical properties such as chemical resistance, water and oil repellency, heat resistance, and electrical properties, and are used in a variety of applications and in various products such as powders and films. The usage pattern is known. Patent Document 1 describes an aqueous dispersion containing a powder of a tetrafluoroethylene polymer, a powder of a depolymerizable acrylic polymer, and an aqueous medium.
In recent years, tetrafluoroethylene-based polymers, which have excellent electrical properties such as low dielectric constant and low dielectric loss tangent, and excellent heat resistance such as solder reflow resistance, have attracted attention as printed circuit board materials compatible with high frequency bands.

Patent Document 2 describes a resin-coated metal foil having a PTFE layer formed from a dispersion of PTFE powder dispersed in a non-aqueous medium, and a method of forming a transmission line on the metal foil to form a printed circuit board. There is. Patent Document 3 describes a non-aqueous dispersion containing PTFE powder as such a dispersion.

International Publication No. 2003/011991 Special table 2015-509113 publication International Publication No. 2016/159102

Formation of a tetrafluoroethylene polymer layer (resin layer) from such a dispersion involves applying the dispersion to the surface of the substrate, evaporating the liquid dispersion medium, and forming a powder-filled layer on the surface of the substrate. Further, the powder is melted or fired. However, tetrafluoroethylene-based polymers are inherently non-tacky and their powders have poor interparticle interactions. Therefore, powder is likely to be missing (powder falling) when forming a filled layer.
Falling powder not only impairs the physical properties of the layer (resin layer), but also contaminates the article itself or manufacturing equipment, reducing its productivity. Therefore, the layer (resin layer) has excellent electrical properties (electrical properties such as dielectric constant and electrostatic dissipation tangent) and surface properties (heat resistance, chemical resistance, smoothness, gloss, etc.) while suppressing powder falling. ) is needed.

As a result of extensive studies, the present inventors have found that a dispersion containing a predetermined (meth)acrylic polymer and a tetrafluoroethylene polymer powder at a predetermined ratio has good electrical and surface properties while suppressing powder falling off. It was discovered that a layer (resin layer) with excellent properties could be formed.

The present invention has the following aspects.
[1] A dispersion liquid containing a powder of a tetrafluoroethylene polymer, a (meth)acrylic polymer having a glass transition point of 0 to 120°C, and a liquid dispersion medium, in which the tetrafluoroethylene polymer is dispersed in the liquid dispersion medium. A dispersion containing 0.1 to 10 parts by mass of the (meth)acrylate polymer based on 100 parts by mass of the tetrafluoroethylene polymer.
[2] The dispersion according to [1], which contains 0.1 or more and less than 5 parts by mass of the (meth)acrylate polymer based on 100 parts by mass of the tetrafluoroethylene polymer.
[3] The dispersion according to [1] or [2], wherein the liquid dispersion medium is a non-aqueous medium.
[4] The dispersion according to any one of [1] to [3], wherein the liquid dispersion medium is an ester or an amide.
[5] The tetrafluoroethylene polymer has at least one functional group selected from the group consisting of a carbonyl group-containing group, a hydroxy group, an epoxy group, an oxetanyl group, an amino group, a nitrile group, and an isocyanate group. ] to [4]. The dispersion according to any one of [4].
[6] The dispersion according to any one of [1] to [5], wherein the (meth)acrylic polymer has a hydroxy group.
[7] The (meth)acrylic polymer may include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, isobornyl (meth)acrylate, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, and benzyl ( The dispersion according to any one of [1] to [6], which contains a unit based on at least one (meth)acrylate selected from the group consisting of meth)acrylates.
[8] The dispersion according to any one of [1] to [7], wherein the (meth)acrylic polymer is a methacrylate polymer.
[9] The dispersion according to any one of [1] to [8], wherein the (meth)acrylic polymer has a weight average molecular weight of 10,000 to 150,000.
[10] The dispersion according to any one of [1] to [9], further comprising a fluorine-based dispersant.
[11] The dispersion according to any one of [1] to [10], further comprising at least one fluorine-based dispersant selected from the group consisting of fluoroalcohol, fluorosilicone, and fluoropolyether.
[12] A method for producing a resin-coated metal foil comprising a metal foil and a resin layer that is provided in contact with the surface of the metal foil and includes a tetrafluoroethylene polymer, the method comprising:
The dispersion according to any one of [1] to [11] is applied to the surface to form a coating layer from the dispersion, and the liquid dispersion medium is removed by heating, and the tetrafluoroethylene-based A method for manufacturing a resin-coated metal foil, comprising forming the resin layer by melting or firing a polymer.
[13] The manufacturing method according to [12], wherein the coating layer is formed at a temperature equal to or higher than the glass transition point of the (meth)acrylic polymer.
[14] The manufacturing method according to [12] or [13], wherein the resin layer is formed at 250°C to 400°C.
[15] The manufacturing method according to any one of [12] to [14], wherein the resin layer has a thickness of less than 20 μm.

According to the present invention, while suppressing the falling of powder particles, the electrical properties (dielectric constant, electrostatic dissipation tangent, etc.) and surface physical properties (heat resistance, chemical resistance, smoothness, gloss, etc.) are excellent. A dispersion containing a tetrafluoroethylene polymer capable of forming a layer (resin layer) is provided.

The following terms have the following meanings:
"D50 of powder" is the point on the cumulative curve where the particle size distribution of the powder is measured by the laser diffraction/scattering method, the total volume of the powder particles is taken as 100%, and the cumulative volume becomes 50%. particle diameter (volume-based cumulative 50% diameter).
"Powder D90" is the point on the cumulative curve where the cumulative volume is 90% by measuring the particle size distribution of the powder using a laser diffraction/scattering method and calculating a cumulative curve with the total volume of the powder particle population as 100%. particle size (volume-based cumulative 90% diameter).
"Polymer melt viscosity" is measured in accordance with ASTM D 1238, using a flow tester and a 2Φ-8L die, using a polymer sample (2 g) that has been heated for 5 minutes at the measurement temperature under a load of 0.7 MPa. This is the value measured while maintaining the temperature at the measurement temperature.
The "melting point of a polymer" is the temperature corresponding to the maximum value of the melting peak measured by differential scanning calorimetry (DSC).
"Viscosity" is a value measured using a B-type viscometer at room temperature (25° C.) and a rotation speed of 30 rpm. Repeat the measurement three times and use the average value of the three measurements.
"(Meth)acrylate" is a general term for acrylate and methacrylate.
"(Meth)acrylic acid" is a general term for acrylic acid and methacrylic acid.
The "glass transition point (Tg)" of a polymer is a value determined by differential scanning calorimetry, and if it cannot be measured, it is a value determined from Fox's equation.
The "weight average molecular weight (Mw)" of a polymer is a value determined by gel permeation chromatography using polystyrene as a standard sample and tetrahydrofuran as a developing solvent.
The "pyrolysis initiation temperature" of the polymer was determined using a thermogravimetric analyzer (TG) and a thermogravimetric differential thermal analyzer (TG-DTA). %) The temperature is such that when the temperature is raised at a rate of 10°C/min in an atmosphere, the mass reduction rate is 1% by mass/min or more.
The "unit" in a polymer is a general term for an atomic group derived from one molecule of the monomer formed by polymerization of monomers, and an atomic group obtained by chemically converting a part of the atomic group. The unit may be a unit directly formed by a polymerization reaction, or may be a unit in which a part of said unit is converted into another structure by processing the polymer. Hereinafter, a unit based on monomer a will also be simply referred to as a "monomer a unit." For example, a unit based on tetrafluoroethylene (TFE) is also referred to as a TFE unit.

The dispersion of the present invention comprises a powder of a tetrafluoroethylene polymer (hereinafter also referred to as "TFE polymer") and a (meth)acrylic polymer (hereinafter referred to as "predetermined polymer") having a glass transition point of 0 to 120°C. ) and a liquid dispersion medium.
In the dispersion, the TFE-based polymer is dispersed in a liquid dispersion medium, and the dispersion contains 0.1 to 10 parts by mass of the predetermined polymer based on 100 parts by mass of the TFE-based polymer.
When a layer (resin layer) is formed from the dispersion of the present invention, powder falling is suppressed and the formed layer (resin layer) has excellent electrical properties and surface properties for the following reasons. It will be done.

When forming a coating layer (a layer formed when the liquid dispersion medium of the dispersion of the present invention is removed), the specified polymer decreases its rigidity and viscosity and forms a thin and uniform layer in the gaps between powder particles. It is thought that it will penetrate. Further, it is thought that the predetermined polymer having a (meth)acryloyloxy group forms a thin and dense matrix in the coating layer due to its intermolecular force, thereby suppressing powder falling-off.
On the other hand, certain polymers have lower heat resistance than TFE-based polymers and are more likely to disappear due to thermal decomposition, so they are less likely to damage the physical properties of the layer (resin layer) formed by melting or baking the powder by heating. . In addition, since the predetermined polymer exists thinly in the gaps between powder particles, gas and polymer residue generated due to thermal decomposition are less likely to impede the physical properties of the layer (resin layer). As a result, a layer (resin layer) with excellent surface properties (heat resistance, chemical resistance, smoothness, gloss, etc.) and electrical properties (dielectric constant, electrostatic tangent, etc.) was obtained from the dispersion of the present invention. It is thought that it was formed. This tendency tends to become noticeable when the layer (resin layer) is thin. Therefore, by using the dispersion liquid of the present invention, a printed circuit board material (resin-coated copper foil, etc.) having a thin film-like electrically insulating layer with good surface properties and electrical properties can be easily obtained.

The D50 of the powder in the present invention is preferably 0.05 to 6 μm, particularly preferably 0.1 to 3.0 μm. When the D50 of the powder is within the above range, the powder not only has excellent fluidity and dispersibility, but also has a layer or resin layer (formed from the dispersion of the present invention) containing a melt or fired product of a TFE-based polymer. (hereinafter also referred to as "F layer") has excellent smoothness. The D90 of the powder is preferably 8.0 μm or less, particularly preferably 1.5 to 5.0 μm. When the D90 of the powder is within the above range, the dispersibility of the powder and the homogeneity of the F layer are excellent.
The loosely packed bulk density and the tightly packed bulk density of the powder are preferably 0.08 to 0.5 g/mL and 0.1 to 0.8 g/mL in this order.
The powder in the present invention is a powder whose main component is a TFE-based polymer. The content of the TFE-based polymer in the powder is preferably 80% by mass or more, particularly preferably 100% by mass. Other resins that may be included in the powder include aromatic polyester, polyamideimide, thermoplastic polyimide, polyphenylene ether, polyphenylene oxide, and the like.

The TFE-based polymer in the present invention is a polymer containing units based on tetrafluoroethylene (TFE) (TFE units).
TFE-based polymers include homopolymers consisting essentially of TFE units (hereinafter also referred to as "PTFE"), copolymers containing TFE units and units based on perfluoro(alkyl vinyl ether) (PAVE) (PAVE units), and TFE units and Preference is given to copolymers containing units based on hexafluoropropylene (HFP) (HFP units) or copolymers containing TFE units and units based on fluoroalkylethylene (FAE) (FAE units).

PTFE also includes polymers containing very small amounts of units other than TFE units and low molecular weight PTFE. The polymer preferably contains more than 99.5 mol%, particularly preferably 99.9 mol% or more, of TFE units based on all units contained in the polymer. The melt viscosity of the polymer at 380° C. is preferably 1×10 ² to 1×10 ⁸ Pa·s, particularly preferably 1×10 ³ to 1×10 ⁶ Pa·s.

The low molecular weight PTFE may be PTFE obtained by irradiating high molecular weight PTFE (polymer described in International Publication No. 2018/026012, International Publication No. 2018/026017, etc.). PTFE obtained by using a chain transfer agent during polymerization to produce PTFE (polymer described in JP 2009-1745 A, WO 2010/114033, JP 2015-232082, etc.). It is a polymer having a core-shell structure consisting of a core part and a shell part, and only the shell part is made of low molecular weight PTFE (Japanese Patent Application Publication No. 2005-527652, International Publication No. 2016/170918, JP-A-09 -087334, etc.) may also be used.
The standard specific gravity (specific gravity measured in accordance with ASTM D4895-04) of low molecular weight PTFE is preferably 2.14 to 2.22, more preferably 2.16 to 2.20.

Polymers containing TFE units also include polymers containing units other than TFE units. The polymer preferably contains more than 0.5 mol % of units based on monomers other than TFE units based on the total units contained in the polymer. The units other than TFE are preferably PAVE units, HFP units, FAE units, or units having a functional group as described below.

The polymer containing TFE units preferably has at least one functional group selected from the group consisting of a carbonyl group-containing group, a hydroxy group, an epoxy group, an oxetanyl group, an amino group, a nitrile group, and an isocyanate group. When the TFE-based polymer has the above-mentioned functional group, the interaction between the predetermined polymer and the TFE-based polymer is strengthened, which improves the dispersion physical properties of the dispersion (viscosity, color tone, etc.) and the F layer formation physical properties (adhesion, transparency, etc.) It is also easier to improve. Note that the carbonyl group-containing group includes an amide group.

The above-mentioned functional group may be included in the units constituting the TFE-based polymer, may be included in the terminal groups of the polymer main chain, or may be introduced into the TFE-based polymer by plasma treatment or the like. Examples of TFE-based polymers containing the above-mentioned functional groups in the terminal groups of the polymer main chain include TFE-based polymers having functional groups as terminal groups derived from polymerization initiators, chain transfer agents, and the like.

The above functional group is preferably a hydroxy group or a carbonyl group-containing group, more preferably a carbonyl-containing group, particularly preferably a carbonate group, a carboxy group, a haloformyl group, an alkoxycarbonyl group, an acid anhydride residue or a fatty acid residue, and a carboxy group. or acid anhydride residues are most preferred.
The TFE-based polymer in the present invention is preferably a polymer containing a TFE unit, a PAVE unit, a HFP unit, or a FAE unit, and a unit having a functional group.
The unit having a functional group is preferably a unit based on a monomer having a functional group.
As the monomer having a functional group, a monomer having a carbonyl group-containing group is preferable, and a cyclic monomer having an acid anhydride residue is particularly preferable.
Examples of the cyclic monomer include itaconic anhydride, citraconic anhydride, 5-norbornene-2,3-dicarboxylic anhydride (also known as hymic anhydride; hereinafter also referred to as "NAH"), or maleic anhydride. is preferred.

As PAVE, _{CF2 = CFOCF3} , _{CF2 = CFOCF2CF3 , CF2} = _{CFOCF2CF2CF3 (} PPVE) _{, CF2} = _{CFOCF2CF2CF2CF3 , CF2} =CFO( _CF2 ) ₈ F, and PPVE is preferred.
As FAE, _CH2 =CH( _CF2 ) _2F , _CH2 =CH( _CF2 ) _3F , _CH2 =CH( _CF2 ) _4F , _CH2 =CF( _CF2 ) _3H , _CH2 =CF( _CF2 ) _4H is mentioned.
In this case, TFE units, PAVE units, HFP units, or FAE units, and units having functional groups are, in this order, 90 to 99 mol% and 0.5 to 9.97 mol% of all units contained in the polymer. , is preferably contained in an amount of 0.01 to 3 mol%. In this case, the melting point of the TFE-based polymer is preferably 250 to 380°C, particularly preferably 280 to 350°C. Specific examples of such TFE-based polymers include the polymers described in International Publication No. 2018/16644.

The predetermined polymer in the present invention is a (meth)acrylic polymer having a glass transition point of 0 to 120°C. (Meth)acrylic polymer is a general term for polymers containing units based on (meth)acrylate.
The predetermined polymer may be dispersed in the form of particles in the dispersion liquid, or may be dissolved in the dispersion liquid.
The glass transition point of a given polymer is preferably 30 to 120°C, preferably 40 to 110°C, particularly preferably 60 to 100°C. In this case, the fluidity of the predetermined polymer in forming the coating layer increases, powder falling-off is further suppressed, and the physical properties of the F layer are more likely to be improved.
The thermal decomposition initiation temperature of the predetermined polymer is preferably 200°C or higher, particularly preferably 250 to 300°C. Further, the thermal decomposition rate of the predetermined polymer at 350° C. is preferably 1% by mass/min or more, particularly preferably 2% by mass/min or more. In this case, the predetermined polymer forms a dense matrix in the coating layer formed from the dispersion, and the predetermined polymer is easily decomposed in forming the F layer, making it easy to form the F layer with excellent electrical properties. .

Preferably, the given polymer has hydroxy groups. In this case, not only the interaction between the predetermined polymers is further improved, but also the interaction between the liquid dispersion medium and the TFE-based polymer is likely to be improved. As a result, falling of the powder is further suppressed, and the physical properties of the F layer are more likely to be improved.
The hydroxyl group may be contained within a given polymer unit or may be contained at the end of the polymer chain (the end of the polymer main chain).
The predetermined polymer is a (meth)acrylate-based polymer containing units based on (meth)acrylate having a hydroxy group, or a polymer chain terminal obtained by polymerizing (meth)acrylate in the presence of a chain transfer agent and an alcohol. A (meth)acrylate polymer having a hydroxyl group is preferred.

Examples of (meth)acrylates having a hydroxy group include hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Examples include (meth)acrylate, monoglycidyl ether, or (meth)acrylate obtained by adding glycidol and (meth)acrylic acid.
As a chain transfer agent, 1-butanethiol, 1-octanethiol, 1-decanethiol, 1-dodecanethiol, 1-hexadecanethiol, cyclohexanethiol, 2-mercaptoethanol, mercaptoacetic acid, methylmercaptoacetate, 3-mercaptopropion acid, 2,4-diphenyl-4-methyl-1-pentene.
Examples of alcohol include methanol, ethanol, and propanol.

Preferably, the given polymer contains units based on hydrocarbon-based (meth)acrylates, such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, cyclohexyl (meth)acrylate and benzyl (meth)acrylate. More preferably, it contains a unit based on at least one (meth)acrylate selected from the group consisting of. In this case, the glass transition point of the predetermined polymer and the thermal decomposability of the predetermined polymer can be easily adjusted, the falling of the powder when forming the F layer is further suppressed, and the physical properties thereof are more easily improved. Note that butyl (meth)acrylate may be any of n-butyl (meth)acrylate, iso-butyl (meth)acrylate, and tert-butyl (meth)acrylate.

The weight average molecular weight of the predetermined polymer is preferably 10,000 to 150,000. In this case, not only the fluidity of the predetermined polymer in the formation of the coating layer increases, but also the degradability of the predetermined polymer improves, so that the falling of the powder of the dispersion of the present invention is further suppressed, and the F layer physical properties are easier to improve.

Specific examples of the predetermined polymer include a polymer having a weight average molecular weight of 50,000 to 150,000 and containing a unit based on the monomer having a hydroxy group and a unit based on the hydrocarbon (meth)acrylate; Examples include polymers comprising units based on acrylate and having a weight average molecular weight of 10,000 to 50,000. Note that the latter polymer preferably has a hydroxy group at the end of the polymer chain.
The former polymer contains units based on a monomer having a hydroxy group and units based on the hydrocarbon (meth)acrylate, in this order, 1 to 20 mol% and 80 to 99 mol% of all units contained in the polymer. It is preferable to include %.

The predetermined polymer is preferably a methacrylate polymer. Note that methacrylate-based polymer is a general term for polymers containing units based on methacrylate. When the predetermined polymer is a methacrylate polymer, it is thought that a denser matrix is formed due to intermolecular forces based on the steric configuration of the polymer main chain, and powder falling off at the edge of the F layer is more likely to be suppressed.
Specific examples of methacrylate polymers include polymers with a weight average molecular weight of 50,000 to 150,000 that include units based on methacrylate having a hydroxyl group and units based on hydrocarbon methacrylate, and polymers that have a weight average molecular weight of 50,000 to 150,000 and units based on hydrocarbon methacrylate. Examples include polymers having a molecular weight of 10,000 to 50,000.
The former polymer contains, in this order, 1 to 20 mol% and 80 to 99 mol% of units based on methacrylate having a hydroxy group and units based on hydrocarbon methacrylate, based on the total units contained in the polymer. preferable. Further, the glass transition point of the former polymer is preferably 60 to 100°C.
The latter polymer preferably has a hydroxy group at the end of the polymer chain. Further, the glass transition point of the latter polymer is preferably 0 to 40°C.

The hydrocarbon methacrylate is preferably at least one methacrylate selected from the group consisting of methyl methacrylate, ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, and benzyl methacrylate, and methyl methacrylate (MMA), ethyl methacrylate (EMA) ) or butyl methacrylate (BMA) is more preferred. Note that BMA may be any of n-butyl methacrylate, iso-butyl methacrylate, and tert-butyl methacrylate.
The methacrylate having a hydroxy group is preferably hydroxyethyl methacrylate (HEMA), 2-hydroxybutyl methacrylate or 4-hydroxybutyl methacrylate.
Such predetermined polymers are available as commercial products (such as "Oricox KC-1700P" manufactured by Kyoeisha Chemical Co., Ltd.).

The liquid dispersion medium in the present invention is a compound that is liquid at 25°C and has the function of dispersing the powder of the present invention, and may be an aqueous medium or a non-aqueous medium, with a non-aqueous medium being preferred. The water content of the nonaqueous medium is preferably 20,000 ppm or less. The lower limit of the water content of the non-aqueous medium is usually 0 ppm.
If the liquid dispersion medium is a non-aqueous medium (especially an ester or a ketone), the specified polymer will be more easily dispersed or dissolved in the dispersion, and the effect of forming the coating layer (the effect of the specified polymer (formation of a dense matrix, etc.) becomes easier to improve, and powder falling off when forming a thin F layer becomes particularly easy to be suppressed.
The compound of the liquid dispersion medium is preferably an organic medium such as a nitrogen-containing compound, a sulfur-containing compound, an ester, a ketone, or a glycol ether.
The boiling point of the compound of the liquid dispersion medium is preferably 60 to 240°C, particularly preferably 80 to 210°C.
The boiling point of the compound of the liquid dispersion medium is preferably equal to or higher than the glass transition point of the predetermined polymer. The boiling point of the compound of the liquid dispersion medium is preferably equal to or lower than the glass transition point +150°C. In this case, during the formation of the coating layer due to the volatilization of the liquid dispersion medium, the fluidity of the predetermined polymer increases, the falling of the powder is further suppressed, and the physical properties of the formed layer (F layer) are more likely to be improved. .

Specific examples of liquid dispersion medium compounds include water, methanol, ethanol, isopropanol, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, diethyl ether, dioxane, and lactic acid. Examples include ethyl, ethyl acetate, butyl acetate, methyl ethyl ketone, methyl isopropyl ketone, γ-butyrolactone, cyclopentanone, cyclohexanone, ethylene glycol monoisopropyl ether, cellosolve (methyl cellosolve, ethyl cellosolve, etc.).
The compound of the liquid dispersion medium is preferably N,N-dimethylacetamide, N-methyl-2-pyrrolidone or γ-butyrolactone.

The dispersion liquid of the present invention includes a dispersant, an antifoaming agent, an inorganic filler, a dehydrating agent, a plasticizer, a weathering agent, an antioxidant, a binder, a heat stabilizer, a lubricant, an antistatic agent, a whitening agent, and a coloring agent. , a conductive agent, a mold release agent, a surface treatment agent, a viscosity modifier, and a flame retardant.
From the viewpoint of improving the dispersibility of the TFE-based polymer powder in the dispersion and improving the physical properties of the F layer, the dispersion of the present invention preferably contains a dispersant.

A dispersant is a compound that chemically and/or physically adsorbs on the surface of TFE-based polymer powder and has the function of stably dispersing the powder in a liquid dispersion medium. A fluorine-based dispersant (fluorine-based surfactant) having a hydrophilic moiety is preferred, and at least one compound selected from the group consisting of fluoroalcohol, fluorosilicone, and fluoropolyether is particularly preferred. Note that these compounds are compounds other than the TFE-based polymer and the predetermined polymer.

Examples of fluoroalcohols include non-polymeric fluoromonols and polymeric fluoropolyols. Further, some of the hydroxyl groups of the polymeric fluoropolyol may be chemically modified.
Examples of fluorosilicone include polyorganosiloxanes containing C—F bonds in part of their side chains.
Examples of the fluoropolyether include compounds in which some of the hydrogen atoms of polyoxyalkylene alkyl ether are replaced with fluorine atoms.

The fluorine-based dispersant is preferably a polymeric fluoropolyol, more preferably a polymer containing a unit based on fluoroalkyl (meth)acrylate or fluoroalkenyl (meth)acrylate and oxyalkylene glycol mono(meth)acrylate.
Specific examples of the former (meth)acrylate include _CH2 =C( _CH3 )C(O) _OCH2CH2 ( _CF2 ) _6F , _CH2 = _CHC (O) _OCH2CH2 ( _{CF2 ) 6F} , _CH2 =C( _CH3 )C(O) _OCH2CH2 ( _CF2 ) _4F , _{CH2 =} CClC(O) _OCH2CH2 ( _CF2 ) _4F , _CH2 =CHC( _O ) _{OCH2CH2CH2CH2OCF} ( _{CF3 )} C(=C _{( CF3 ) 2} ) _{( CF} ( _{CF3 ) 2} ), _CH2 =CHC ₍ O)OCH2CH2CH2CH2OC( CF ₃ )C(=C(CF(CF ₃ ) ₂ ) ₂ ).
The amount of the former unit based on the total units contained in the polymer is preferably 60 to 90 mol%, particularly preferably 70 to 90 mol%.

Specific examples of the latter (meth)acrylate include _CH2 = _{C ( CH3} )C(O)( _OCH2CH2 ) _2OH , _CH2 =C( _CH3 )C(O)( _OCH2CH2 ) _{9 OH} , _CH2 =C( _CH3 )C(O)( _OCH2CH2 ) ₂₃ OH, _CH2 =C( _CH3 )C(O)( _{OCH2CH2 ) 66} OH, _CH2 =CHC (O) (OCH ₂ CH ₂ ) ₄ OH, CH ₂ =CHC(O) (OCH ₂ CH ₂ ) ₉ OH, CH ₂ =CHC(O) (OCH ₂ CH ₂ ) ₂₃ OH, CH ₂ =CHC(O )( _{OCH2CH2 ) 66} OH, _{CH2 =C(CH3)C(O)(OCH2CH(CH3))4 OH,CH2=C(CH3 ) C ( O )} ( _{OCH2CH 2} ) _4. (OCH ₂ CH(CH ₃ )) ₃ OH, CH ₂ =C(CH ₃ )C(O)(OCH ₂ CH ₂ ) _10. (OCH ₂ CH ₂ CH ₂ CH ₂ ) ₅ OH is listed. It will be done.
The amount of the latter units relative to the total units contained in the polymer is preferably 10 to 40 mol%, particularly preferably 10 to 30 mol%.

The polymer may further include other additional units.
Preferably, the polymer is nonionic.
The weight average molecular weight of the polymer is preferably 2,000 to 80,000, particularly preferably 6,000 to 20,000.
The polymer may have a hydroxyl group or a carboxyl group at the end of the main chain. In this case, the leveling properties of the dispersion of the present invention tend to improve. Such polymers can be obtained by adjusting the types of polymerization initiators and chain transfer agents used in their production.

The proportion of powder in the dispersion is preferably 5 to 60% by weight, particularly preferably 30 to 50% by weight. In this case, the dispersibility of the dispersion liquid and the physical properties of the F layer tend to improve.
The proportion of the liquid dispersion medium in the dispersion is preferably 15 to 65% by weight, particularly preferably 25 to 50% by weight. In this case, the formation of the coating layer from the dispersion and the physical properties of the F layer are likely to be improved.
The proportion of the predetermined polymer in the dispersion is preferably 0.05 to 6% by weight, particularly preferably 0.1 to 5% by weight. In this case, the dispersibility of the dispersion liquid and the physical properties of the F layer tend to improve.

The dispersion liquid of the present invention contains 0.1 to 10 parts by mass of a predetermined polymer based on 100 parts by mass of TFE-based polymer. The content of the predetermined polymer based on 100 parts by mass of the TFE-based polymer is preferably 0.5 parts by mass or more, particularly preferably 1 part by mass or more. The content is preferably 5 parts by mass or less, particularly preferably less than 5% by mass. In this case, falling of the powder of the coating layer formed from the dispersion of the present invention is further suppressed, and the physical properties of the F layer are more likely to be improved. Further, it is easier to form a thin film-like electrical insulating layer having good surface properties and electrical properties.
If the dispersion of the invention contains other materials, the proportion of the other materials in the dispersion is preferably from 1 to 50% by weight, particularly preferably from 5 to 30 parts by weight. Note that when the other material contains a dispersant, the proportion of the dispersant in the dispersion is preferably 1 to 10 parts by mass.

The dispersion of the present invention can be produced by mixing a liquid dispersion medium, a TFE-based polymer powder, and a predetermined polymer, and can be produced by mixing a liquid dispersion medium, a predetermined polymer, and a TFE-based polymer powder. preferable.
When mixing, it is preferable to perform a dispersion treatment using a homodisper or a homogenizer to improve the dispersion state. Furthermore, when using the dispersion of the present invention stored at 0 to 40°C, it is preferable to carry out these dispersion treatments before use.

In the present invention, the dispersion of the present invention is applied to the surface of metal foil to form a coating layer, and the TFE-based polymer is further melted or fired by heating to form a resin layer (F layer) containing the TFE-based polymer. Form. Thereby, it is possible to provide a resin-coated metal foil that includes a metal foil and a resin layer that is provided in contact with the surface of the metal foil and includes a TFE-based polymer.
In the production method of the present invention, the ranges of the TFE-based polymer, its powder, the predetermined polymer, and the liquid dispersion medium, including their preferred embodiments, are the same as those for the polymer dispersion of the present invention. Further, in the manufacturing method of the present invention, it is sufficient that the resin layer is formed on at least one surface of the metal foil, the resin layer may be formed on only one side of the metal foil, or the resin layer is formed on both surfaces of the metal foil. may be formed.

Examples of the material of the metal foil include copper, copper alloy, stainless steel, nickel, nickel alloy (including 42 alloy), aluminum, aluminum alloy, titanium, titanium alloy, and the like.
As the metal foil, copper foils such as rolled copper foil and electrolytic copper foil are preferred.
A rust-proofing layer or a heat-resistant layer may be disposed on the surface of the metal foil. Moreover, the surface of the metal foil may be surface-treated with a silane coupling agent.
The thickness of the metal foil may be as long as it can exhibit a sufficient function in the application of the laminate. The thickness of the metal foil is greater than or equal to the ten-point average roughness of its surface, and is preferably 2 to 40 μm. As the metal foil, a carrier-attached metal foil consisting of a carrier copper foil (10 to 35 μm thick) and an ultra-thin copper foil (2 to 5 μm thick) laminated on the carrier copper foil via a release layer is used. It's okay. Further, the thickness of the metal foil is preferably greater than the thickness of the F resin layer.

Methods for applying the dispersion include spray method, roll coating method, spin coating method, gravure coating method, microgravure coating method, gravure offset method, knife coating method, kiss coating method, bar coating method, die coating method, and Fountain Meyer bar method. , slot die coating method.

The coating layer is preferably formed by heating the metal foil at a temperature equal to or higher than the glass transition point of a predetermined polymer to remove the liquid dispersion medium. At this time, it is not necessary to completely volatilize the liquid dispersion medium, but it is sufficient to volatilize the liquid dispersion medium to the extent that a stable self-supporting film is formed from the coating layer formed by applying the dispersion liquid. Specifically, it is preferable to volatilize 50% by mass or more of the liquid dispersion medium contained in the dispersion. Note that the liquid dispersion medium that has not been volatilized can be completely removed in the next melting or firing step.
The temperature at this time is preferably 50 to 150°C, more preferably 80 to 120°C.
The time at this time is preferably 0.1 to 30 minutes, more preferably 0.5 to 20 minutes.

The temperature at which the coating layer is heated to melt or bake the TFE-based polymer to form a resin layer containing the TFE-based polymer is preferably 250°C to 400°C, particularly preferably 300 to 400°C.
Examples of the heating method include a method using an oven, a method using a ventilation drying oven, and a method of irradiating with heat rays such as infrared rays. In order to improve the surface smoothness of the F layer, pressure may be applied using a heating plate, heating roll, or the like. Note that the temperature in heating usually indicates the temperature of the atmosphere. The effective wavelength band of infrared rays is particularly preferably 3 to 7 μm from the viewpoint of homogeneously melting or baking the TFE polymer.
The atmosphere for heating preferably has an oxygen gas concentration of 100 to 500 ppm from the viewpoint of suppressing oxidation of the metal foil and F layer. Further, the atmosphere is preferably an inert gas (nitrogen gas, etc.) atmosphere or a reducing gas atmosphere (hydrogen gas, etc.).

The thickness of the resin layer formed is preferably less than 20 μm, more preferably less than 10 μm. The thickness of the resin layer is preferably 1 μm or more. In the dispersion of the present invention, the content of the predetermined polymer relative to the content of the TFE polymer is within a predetermined range, and even in the formation of such a thin resin layer, a dense layer of the TFE polymer is formed due to the action of the predetermined polymer. Not only is this possible, but it is also difficult for certain polymers to remain in the resin layer. As a result, a thin film-like resin layer with excellent surface properties and electrical properties can be easily formed, and a resin-coated copper foil that is resistant to warping can be easily obtained.

In the resin-coated metal foil of the present invention, the surface of the resin layer may be subjected to surface treatment in order to control the linear expansion coefficient of the resin layer or further improve the adhesiveness of the resin layer.
Examples of the surface treatment include annealing treatment, corona discharge treatment, atmospheric pressure plasma treatment, vacuum plasma treatment, UV ozone treatment, excimer treatment, chemical etching, silane coupling treatment, and micro-roughening treatment.
The temperature in the annealing treatment is preferably 80 to 190°C. The pressure in the annealing treatment is preferably 0.001 to 0.030 MPa. The annealing time is preferably 10 to 300 minutes.

Examples of plasma irradiation equipment used in plasma processing include high-frequency induction type, capacitively coupled electrode type, corona discharge electrode-plasma jet type, parallel plate type, remote plasma type, atmospheric pressure plasma type, and ICP type high-density plasma type. .
Examples of the gas used in the plasma treatment include oxygen gas, nitrogen gas, rare gas (argon, etc.), hydrogen gas, ammonia gas, and the like, with rare gas or nitrogen gas being preferred. Specific examples of the gas used for plasma processing include argon gas, a mixed gas of hydrogen gas and nitrogen gas, and a mixed gas of hydrogen gas, nitrogen gas, and argon gas.
The atmosphere in the plasma treatment is preferably an atmosphere in which the volume fraction of rare gas or nitrogen gas is 70% by volume or more, and particularly preferably 100% by volume. In this range, by adjusting Ra of the surface of the F resin layer to 2.5 μm or less, it is easy to form fine irregularities on the surface of the F layer of the resin-coated metal foil.

Ra of the surface of the F layer in the resin-coated metal foil is preferably 2 nm to 2.5 μm, particularly preferably 5 nm to 1 μm. The surface Rz of the F layer is preferably 15 nm to 2.5 μm, particularly preferably 50 nm to 2 μm. Within this range, it is easy to balance the adhesiveness between the resin-coated metal foil and the prepreg and the surface workability of the F layer.
As a method for laminating the prepreg on the surface of the F layer of the resin-coated metal foil, there is a method of hot pressing the resin-coated metal foil and the prepreg.

The pressing temperature is preferably below the melting point of the TFE polymer, particularly preferably from 160 to 220°C. Within this range, the F layer and the prepreg can be firmly bonded while suppressing thermal deterioration of the prepreg.
It is particularly preferable that the heat press be performed at a vacuum degree of 20 kPa or less. Within this range, the incorporation of air bubbles into the interfaces of the metal foil, F layer, and cured material layer in the laminate and deterioration due to oxidation can be suppressed. Further, during hot pressing, it is preferable to raise the temperature after reaching the above-mentioned degree of vacuum.
The pressure in the hot press is preferably 0.2 to 10 MPa. Within this range, the F layer and the prepreg can be firmly bonded while suppressing damage to the prepreg.

The resin-coated metal foil of the present invention has a resin layer made of TFE-based polymer, which has excellent physical properties such as electrical properties and chemical resistance (etching resistance). It can be used as a rigid metal clad laminate to manufacture printed circuit boards.
For example, the resin-coated metal foil of the present invention may be etched to form a conductor circuit (transmission circuit) with a predetermined pattern, or the resin-coated metal foil of the present invention may be processed by electrolytic plating (semi-additive plating). A printed circuit board can be manufactured from the resin-coated metal foil of the present invention by processing it into a transmission circuit by a modified semi-additive method (SAP method), modified semi-additive method (MSAP method), etc.

The printed circuit board manufactured from the resin-coated metal foil of the present invention preferably has a transmission circuit, an F layer, and a cured material layer in this order. Examples of the layer structure of the printed circuit board of the present invention include transmission circuit/F layer/cured material layer, transmission circuit/F layer/cured material layer/F layer/transmission circuit.
In manufacturing a printed circuit board, after forming a transmission circuit, an interlayer insulating film may be formed on the transmission circuit, and a transmission circuit may be further formed on the interlayer insulating film. The interlayer insulating film can also be formed using, for example, the dispersion of the present invention.
In manufacturing printed circuit boards, a solder resist may be laminated on the transmission circuit. A solder resist can be formed using the dispersion of the present invention.
In manufacturing printed circuit boards, a coverlay film may be laminated on the transmission circuit. Coverlay films can also be formed with the dispersions of the present invention.

EXAMPLES Hereinafter, the present invention will be explained in detail with reference to Examples, but the present invention is not limited thereto.
Various evaluations were performed using the following methods.
<Powder falling off of coating layer (Part 1)>
The metal foil with the dispersion applied and dried to form a coating layer is wound up into a roll and stored for 10 days. After that, a 10m long metal foil is rolled out from the roll, and the number of powder (detachable powder) adhering to the back side of the metal foil (the side on which the coating layer is not formed) is visually checked and evaluated using the following criteria. did.
○: The number of detached powders is less than 5.
×: The number of detached powders is 5 or more.
<Powder falling off of coating layer (Part 2)>
After the dispersion was applied and dried to form a coating layer, the edges of the metal foil were visually checked and evaluated according to the following criteria.
○: Missing is not confirmed.
△: Missing parts are confirmed.
×: Missing areas have also expanded to the periphery.
<Smoothness of resin-coated copper foil>
The surface of the F layer of the resin-coated copper foil was irradiated with light, visually checked from diagonally above, and evaluated using the following criteria.
○: Yuzu skin pattern is not observed.
×: Yuzu skin pattern is confirmed.
Details and abbreviations of the materials used are as follows.

<TFE polymer>
Polymer F1: A copolymer containing 97.9 mol%, 0.1 mol%, and 2.0 mol% of TFE units, NAH units, and PPVE units in this order, and has a melting point of 300°C.
<(meth)acrylate polymer>
Polymer A1: A polymer containing 60 mol%, 20 mol%, and 10 mol% of EMA units, MMA units, and HEMA units in this order, and having a Tg of 75°C and a Mw of 120,000.
Polymer A2: A polymer consisting of BMA units and having a Tg of 25°C and a Mw of 25,000.
Polymer A3: A polymer containing 60 mol%, 20 mol%, and 10 mol% of EMA units, MMA units, and HEMA units in this order, and has a Tg of 65°C and a Mw of 100,000.
<Liquid dispersion medium>
NMP: N-methylpyrrolidone (boiling point: 202°C)

[Example 1] Production example of dispersion [Example 1-1] Production example of dispersion 1 Powder F1 of polymer F1 (D50: 2.6 μm , D90: 7.1 μm).
3209 g of Powder F1, 320.9 g of fluorine-based dispersant (Ftergent 710FL, manufactured by Neos), 2888 g of NMP, and 97.7 g of Polymer A1 were placed in a horizontal ball mill pot, and dispersed using 15 mm diameter zirconia balls. , Dispersion 1 in which powder of Polymer A1 was dispersed was obtained. The viscosity of Dispersion 1 was 180 mPa·s at 60 rpm.

[Example 1-2] Production example of dispersion liquid 2 As a fluorine-based dispersant, a unit based on CH ₂ = C (CH ₃ ) C (O) OCH ₂ CH ₂ (CF ₂ ) ₆ F and a unit based on CH ₂ = C (CH Example 1 except that polymers containing 81 mol% and 19 mol% of units based on 3) C(O ₎ (OCH ₂ CH ₂ ) ₂₃ OH in this order were used, and polymer A2 was used instead of polymer A1. Dispersion 2 was obtained in the same manner as in Example 1. The viscosity of Dispersion 2 was 160 mPa·s at 60 rpm.
[Example 1-3] Production Example of Dispersion 3 Dispersion 3 was obtained in the same manner as Example 1-1 except that Polymer A3 was used instead of Polymer A1. The viscosity of Dispersion 3 was 150 mPa·s at 60 rpm.
[Example 1-4] Production example of dispersion liquid 4 Same as Example 1-1 except that polymer A2 was used instead of polymer A1 and 15 parts by mass of polymer A2 was used for 100 parts by mass of polymer F1. Dispersion 4 was obtained.
Note that when dispersions 1 to 3 were applied to the surface of copper foil immediately after preparation and heated, a resin-coated copper foil having an F layer (thickness: 5 μm) containing polymer F1 could be produced. Resin-coated copper foils having F layers with a thickness of 7 μm and a thickness of 10 μm were also produced without any problem.

[Example 2] Manufacturing example of resin-coated metal foil (Part 1)
[Example 2-1]
Dispersion 1 was stirred with a paint shaker for 1 hour, stirred with a homomixer for 30 minutes at 3000 rpm, filtered with mesh (pore size 100 μm), and then placed in a tank connected to a gravure coater via a liquid feed line. A stirring device with stirring blades was installed and operated in the tank, and a filtration filter was installed in the liquid feeding line.
Using a gravure coater, dispersion liquid 1 was applied to the roughened surface of a long copper foil (Fukuda Metal Foil & Powder Industries Co., Ltd., CF-T4X-SV, width 640 mm, thickness 18 μm) that was moving at a conveyance speed of 10 m/min. The coating was applied to a thickness of 5 μm to form a wet film on the roughened surface. Subsequently, the long copper foil with the wet film was passed through a ventilation drying oven to volatilize the liquid dispersion medium and form a coating layer. The conditions in the ventilation drying oven were 100° C. for 1.5 minutes.

Furthermore, the copper foil was passed through a far-infrared furnace (NORITAKE Co., Ltd., roll-to-roll type NORITAKE far-infrared rays, N2 atmosphere furnace, length 4.7 m) while moving at a conveyance speed of 5 m/min to melt and bake the polymer F1. As a result, a long resin-coated copper foil having an F layer containing polymer F1 was obtained. The heating conditions in the far-infrared furnace were 370° C. for 1 minute in a nitrogen gas atmosphere with an oxygen gas concentration of 200 ppm.
The surface of the F layer of the obtained resin-coated copper foil was subjected to plasma treatment. As the plasma processing apparatus, a roll-to-roll type vacuum plasma apparatus of NVC-R series/RollVIA system manufactured by Nippon Denshi Co., Ltd. was used. The plasma processing conditions were: output: 4.5 kW, introduced gas: argon gas, introduced gas flow rate: 50 cm 3 /min, pressure: 50 mTorr (6.7 Pa), and processing time: 2 minutes.

FR-4 (manufactured by Hitachi Chemical Co., Ltd., GEA-67N 0.2t (HAN), reinforcing fiber: glass fiber, matrix resin: epoxy resin) was applied to the surface of the F layer of the resin-coated copper foil within 72 hours after plasma treatment. , thickness: 0.2 mm), and vacuum hot pressing was performed under the conditions of press temperature: 185° C., press pressure: 3.0 MPa, and press time: 60 minutes to obtain a laminate. The evaluation results for powder removal from the coating layer (Part 1), powder removal from the coating layer (Part 2), and smoothness of the resin-coated copper foil were each "Good".

[Example 2-2] to [Example 2-4]
A resin-coated copper foil was prepared in the same manner as in Example 2-1, except that dispersion 2, 3 or dispersion 1 (dispersion C) containing no (meth)acrylate polymer was used instead of dispersion 1. Manufactured. The evaluation results of the coating layer of each resin-coated copper foil are summarized in Table 1.

[Example 3] Manufacturing example of resin-coated metal foil (Part 2)
[Example 3-1]
Dispersion 2 was applied roll-to-roll by the gravure reverse method onto the same copper foil as in Example 2 to form a wet film. Then, it was heated and dried in a drying oven at 120° C. for 5 minutes to form a coating layer. The dried coating was then heated at 380° C. for 3 minutes under a nitrogen oven. Thereby, a resin-coated copper foil having an F layer (thickness: 4 μm) formed by melting and firing the polymer F1 on the surface of the copper foil was obtained.
This resin-coated copper foil was subjected to plasma treatment in the same manner as in Example 2, and prepreg was layered in the same manner as in Example 2 to obtain a laminate having copper foil, an F layer, and a cured prepreg layer in this order. In a soldering heat resistance test in which this laminate was floated in a solder bath, even when it was floated in a solder bath at 288°C for 5 seconds five times, the phenomenon of swelling at the interface between the F layer and the cured material layer (blister phenomenon) and the phenomenon that the F layer A phenomenon in which the copper foil floats (floating phenomenon) did not occur.

[Example 3-2]
A laminate having a copper foil, an F layer, and a cured prepreg layer in this order was obtained in the same manner as Example 3-1 except that Dispersion 4 was used instead of Dispersion 2.
The results of the solder heat resistance test for each laminate are summarized in Table 2. The value of "Polymer A2/Polymer F1" in the table is the content (parts by mass) of Polymer A2 per 100 parts by mass of Polymer F1 contained in the dispersion used.

The dispersion liquid of the present invention can form an article having a TFE polymer layer (F layer) that suppresses powder falling during layer (F layer) formation and has excellent electrical properties and surface properties. Can be used for fiber-reinforced films, prepregs, resin-coated metal foils, metal-clad laminates, printed circuit boards, etc. Further, the dispersion of the present invention is useful as a material for antenna parts, printed circuit boards, aircraft parts, automobile parts, sports equipment, food industry products, saws, sliding bearings, and the like.

In addition, Japanese Patent Application No. 2018-188254 filed on October 3, 2018, Japanese Patent Application No. 2018-218320 filed on November 21, 2018, and Japanese Patent Application No. 2018-218320 filed on April 4, 2019. The entire contents of the specification, claims, and abstract of patent application No. 2019-071907 are cited here and incorporated as disclosure of the specification of the present invention.

Claims (8)

A powder of a tetrafluoroethylene polymer having a carbonyl group-containing group , a (meth)acrylic polymer having a glass transition point of 0 to 120°C, and a liquid dispersion medium, the tetrafluoroethylene polymer being dispersed in the liquid dispersion medium. A dispersion containing 0.1 or more and less than 5 parts by mass of the (meth)acrylate polymer based on 100 parts by mass of the tetrafluoroethylene polymer. The dispersion according to claim 1, wherein the liquid dispersion medium is a non-aqueous medium. The dispersion liquid according to claim 1 or 2 , wherein the liquid dispersion medium is an ester or an amide. The dispersion liquid according to any one of claims 1 to 3 , wherein the (meth)acrylic polymer has a hydroxy group. The (meth)acrylic polymer is methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, isobornyl (meth)acrylate, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, and benzyl (meth)acrylate. Dispersion according to any one of claims 1 to 4 , comprising at least one (meth)acrylate-based unit selected from the group consisting of: The dispersion according to any one of claims 1 to 5 , wherein the (meth)acrylic polymer is a methacrylate polymer. The dispersion according to any one of claims 1 to 6 , wherein the (meth)acrylic polymer has a weight average molecular weight of 10,000 to 150,000. The dispersion according to any one of claims 1 to 7 , further comprising a fluorine-based dispersant.