WO2021235252A1

WO2021235252A1 - Method for producing laminate which has layer containing thermofusible tetrafluoroethylene polymer

Info

Publication number: WO2021235252A1
Application number: PCT/JP2021/017605
Authority: WO
Inventors: 敦美山邊; 文伊藤
Original assignee: Ａｇｃ株式会社
Priority date: 2020-05-21
Filing date: 2021-05-08
Publication date: 2021-11-25
Also published as: CN115666942A; KR20230010621A; TW202204507A; JPWO2021235252A1

Abstract

[Problem] To provide a production method for providing a laminate which exhibits excellent peeling strength and reliability such as water resistance, and improves adhesion between a substrate and a layer which has a tetrafluoroethylene polymer. [Solution] A method for producing a laminate which has a layer containing a thermofusible tetrafluoroethylene polymer, said method involving the formation of a layer containing a thermofusible tetrafluoroethylene polymer by coating a substrate with a dispersion containing a powder of a thermofusible tetrafluoroethylene polymer, forming a coating film by drying the same, and heating the obtained coating film, wherein the steps from at least forming the coating film until after the layer has been formed involve heating and compressing the substrate and the coating film or layer.

Description

A method for producing a laminate having a layer containing a heat-meltable tetrafluoroethylene polymer.

The present invention relates to a method for producing a laminate having a layer containing a heat-meltable tetrafluoroethylene polymer.

Tetrafluoroethylene-based polymers have excellent physical properties such as electrical insulation, water and oil repellency, chemical resistance, and heat resistance, and are widely used in electronic device parts, automobile parts, and the like. In particular, since tetrafluoroethylene polymers are excellent in low dielectric property and low dielectric loss tangent property, their use in the field of electronic devices is attracting attention by taking advantage of their characteristics.

For example, a laminate in which a tetrafluoroethylene polymer and a metal substrate such as copper are laminated, or a laminate in which a tetrafluoroethylene polymer and a polyimide resin having excellent heat resistance are laminated is used as a printed circuit substrate. However, since the tetrafluoroethylene polymer is inferior in adhesiveness to other resins and metals, various attempts have been made to improve the adhesiveness.

For example, Patent Document 1 describes a method for producing a laminate in which a dispersion liquid containing a powder of a tetrafluoroethylene polymer is applied onto a substrate and heated to form a layer containing the tetrafluoroethylene polymer. .. However, the layer formed by such a manufacturing method may swell or crack due to gas or the like generated during heating. As a result, it is known that uneven thickness of the layer and variation in electrical characteristics occur (Patent Document 2).

International Publication 2016/159102 Japanese Unexamined Patent Publication No. 2013-22899

Therefore, a layer containing a tetrafluoroethylene polymer is included in the laminate in which a dispersion containing the tetrafluoroethylene polymer is applied onto a substrate of another resin or metal and heated to form a layer containing the tetrafluoroethylene polymer. It has been required to improve the adhesiveness between the substrate and the substrate, the water resistance of the laminate and the peel strength, suppress the deterioration of the peel strength during use, that is, improve the reliability of the laminate in use.

The present inventors have produced a laminate having the layer and the substrate for the purpose of providing a laminate having excellent peel strength and water resistance, in which the adhesiveness between the layer containing the tetrafluoroethylene polymer and the substrate is improved. The method was examined and the present invention was completed.

The present invention provides a manufacturing method for improving the adhesiveness between a layer containing a tetrafluoroethylene polymer and a substrate to give a laminate having excellent peel strength and water resistance.

The present invention has the following aspects.
A dispersion containing a powder of a heat-meltable tetrafluoroethylene polymer is applied onto a substrate and dried to form a coating film, and the obtained coating film is further heated to further heat the heat-meltable tetrafluoroethylene polymer. A layer containing a heat-meltable tetrafluoroethylene-based polymer that heats and compresses the coating film or the layer and the substrate in the process from the formation of the coating film to the formation of the layer. A method for producing a laminate having.
[2]
The heat-meltable tetrafluoroethylene polymer contains units based on perfluoro (alkyl vinyl ether) and has polar functional groups, or contains 2 to 5 mol% of units based on perfluoro (alkyl vinyl ether) with respect to all units. The method for producing a laminate according to the above [1], which is a polymer having no polar functional group.
[3]
The method for producing a laminate according to the above [1] or [2], wherein the substrate is a copper foil or a polyimide film.
[4]
The temperature of the heat compression is not more than the glass transition temperature of the heat-meltable tetrafluoroethylene polymer and 100 ° C. or less higher than the melting temperature of the heat-meltable tetrafluoroethylene polymer, according to the above [1] to [3]. The method for producing a laminate according to any one.
[5]
The method for producing a laminate according to any one of the above [1] to [4], wherein the heat compression pressure is 0.2 MPa or more and 10 MPa or less.
[6]
The method for producing a laminate according to any one of [1] to [5], wherein the heat compression is performed when the layer is formed.
[7]
The ratio of the thickness of the coating film after heat compression to the thickness of the coating film before heat compression, or the thickness of the layer after heat compression to the thickness of the layer before heat compression. The method for producing a laminate according to any one of the above [1] to [6], wherein the ratio is 0.1 to 0.8.
[8]
The method for producing a laminate according to any one of the above [1] to [7], wherein the thickness of the layer after heat compression is 40 μm or more.
[9]
The method for producing a laminate according to any one of the above [1] to [8], wherein the dispersion further contains an inorganic filler.
[10]
The method for producing a laminate according to any one of the above [1] to [9], wherein the dispersion liquid further contains an inorganic filler surface-treated with a silane coupling agent.
[11]
The method for producing a laminate according to any one of the above [1] to [10], wherein the dispersion liquid contains an inorganic filler having an average particle size of 10 μm or more.
[12]
The laminate according to any one of [9] to [11], wherein the mass ratio of the inorganic filler to the heat-meltable tetrafluoroethylene polymer in the dispersion is 0.5 to 1.5. How to make a body.
[13]
The method for producing a laminate according to any one of the above [1] to [12], wherein the dispersion further contains a non-heat-meltable polytetrafluoroethylene powder.
[14]
The method for producing a laminate according to any one of the above [1] to [13], wherein the dispersion further contains an aromatic polymer.
[15]
The method for producing a laminate according to any one of the above [1] to [14], wherein the dispersion further contains a silane coupling agent.

According to the present invention, it is possible to improve the adhesiveness between the layer containing the tetrafluoroethylene polymer and various substrates, and to produce a laminate having excellent peel strength and water resistance.

The following terms have the following meanings.
The "heat-meltable tetrafluoroethylene-based polymer" is a polymer containing a unit (hereinafter, also referred to as TFE unit) based on tetrafluoroethylene (hereinafter, also referred to as TFE), and has a melt flow rate under the condition of a load of 49N. It means a melt-fluid polymer having a temperature of 1 to 1000 g / 10 minutes.
The "glass transition point (Tg) of the polymer" is a value measured by analyzing the polymer by the dynamic viscoelasticity measurement (DMA) method.
The “polymer melting temperature (melting point)” is the temperature corresponding to the maximum value of the melting peak measured by the differential scanning calorimetry (DSC) method.
“D50” is the average particle size of the object (powder or inorganic filler), and is the volume-based cumulative 50% diameter of the object obtained by the laser diffraction / scattering method. That is, the particle size distribution of the object is measured by the laser diffraction / scattering method, the cumulative curve is obtained with the total volume of the group of objects as 100%, and the particle size at the point where the cumulative volume is 50% on the cumulative curve. be.
“D90” is the cumulative volume particle size of the object, and is the volume-based cumulative 90% diameter of the object obtained in the same manner as “D50”.
The "viscosity of the dispersion liquid" is a value measured for the dispersion liquid at room temperature (25 ° C.) and a rotation speed of 30 rpm using a B-type viscometer. The measurement is repeated 3 times, and the average value of the measured values for 3 times is used.
The "thixotropic ratio of the dispersion liquid" is a value calculated by dividing the viscosity obtained by measuring the dispersion liquid under the condition of a rotation speed of 30 rpm by the viscosity obtained by measuring the dispersion liquid under the condition of a rotation speed of 60 rpm. ..
The "monomer-based unit" means an atomic group based on the monomer formed by polymerization of the monomer. The unit may be a unit directly formed by a polymerization reaction, or may be a unit in which a part of the unit is converted into another structure by processing a polymer. Hereinafter, the unit based on the monomer a is also simply referred to as “monomer a unit”.

The production method of the present invention (hereinafter, also referred to as this method) is a dispersion liquid (hereinafter, this dispersion liquid) containing a powder (hereinafter, also referred to as this powder) of a heat-meltable tetrafluoroethylene polymer (hereinafter, also referred to as F polymer). (Also referred to as) is applied onto a substrate and dried to form a coating film, and the obtained coating film is further heated to form a layer containing the heat-meltable tetrafluoroethylene polymer, and at least the coating film is formed. This is a method for obtaining a laminated body (hereinafter, also referred to as the present laminated body) by heating and compressing the coating film or the layer and the substrate at any stage from the formation of the above layer to the formation of the layer.

The melting temperature of the F polymer contained in this powder is preferably 200 ° C. or higher, and the melting temperature of the F polymer is more preferably 250 ° C. or higher, further preferably 280 ° C. or higher. The melting temperature of the F polymer is preferably 325 ° C. or lower from the viewpoint of moldability.

The glass transition point of the F polymer is preferably 30 to 150 ° C, more preferably 75 to 125 ° C.
The F polymer includes a polymer (hereinafter also referred to as PFA) containing a TFE unit and a unit based on perfluoro (alkyl vinyl ether) (hereinafter also referred to as PAVE) (hereinafter also referred to as PAVE unit) or a unit based on TFE and hexafluoropropylene. A copolymer containing (hereinafter, also referred to as FEP) is preferable, and PFA is particularly preferable. These polymers may further contain units based on other comonomeres.

As the PAVE, CF ₂ = CFOCF ₃ , CF ₂ = CFOCF ₂ CF ₃ or CF ₂ = CFOCF ₂ CF ₂ CF ₃ (hereinafter, also referred to as PPVE) is preferable, and PPVE is more preferable.
The F polymer preferably has a polar functional group. The F polymer having a polar functional group tends to further improve reliability such as adhesiveness to a substrate, which will be described later, peel strength and water resistance of the laminate.

The polar functional group may be contained in the monomer unit in the F polymer, or may be contained in the terminal group of the main chain of the polymer. Examples of the latter embodiment include an F polymer having a polar functional group as a terminal group derived from a polymerization initiator, a chain transfer agent, etc., and an F polymer having a polar functional group obtained by subjecting the F polymer to plasma treatment or ionization line treatment. Be done.
The polar functional group is preferably a hydroxyl group-containing group or a carbonyl group-containing group, and a carbonyl group-containing group is particularly preferable.
When the F polymer has an oxygen-containing polar group, the number of oxygen-containing polar groups in the F polymer is preferably 10 to 5000, more preferably 100 to 3000, per ^{1 × 10 6 carbon atoms in the main chain.} The number of oxygen-containing polar groups in the F polymer can be quantified by the composition of the polymer or the method described in International Publication No. 2020/145133.

The hydroxyl group-containing group is preferably a group containing an alcoholic hydroxyl group, more preferably -CF ₂ CH ₂ OH or C (CF ₃ ) ₂ OH.
The carbonyl group-containing group is a group containing a carbonyl group (> C (O)), a carboxyl group, an alkoxycarbonyl group, an amide group, an isocyanate group, a carbamate group (-OC (O) NH ₂ ), and an acid anhydride residue. Group (-C (O) OC (O)-), imide residue (-C (O) NHC (O)-etc.) or carbonate group (-OC (O) O-) is preferred, and acid anhydride residue. Is particularly preferable.

Suitable embodiments of the F polymer include a polymer (1) containing TFE and PAVE units and having polar functional groups, or 2 to 5 mol of PAVE units per total monomer unit, including TFE and PAVE units. A polymer (2) containing% and having no polar functional group can be mentioned. Since these polymers form microspherulites in the product, the properties of the obtained product tend to be improved.

The polymer (1) is preferably a polymer containing a TFE unit, a PAVE unit, and a unit based on a monomer having a hydroxyl group-containing group or a carbonyl group-containing group. The polymer (1) has 90 to 99 mol% of TFE units, 0.5 to 9.97 mol% of PAVE units, and 0.01 to 3 mol% of units based on the above-mentioned monomers, respectively, with respect to all the units. It is preferable to include it.
Further, the monomer is preferably itaconic anhydride, citraconic anhydride or 5-norbornene-2,3-dicarboxylic acid anhydride (also known as hymic anhydride; hereinafter also referred to as "NAH").
Specific examples of the polymer (1) include the polymers described in International Publication No. 2018/16644.

The polymer (2) is composed of only TFE units and PAVE units, and preferably contains 95 to 98 mol% of TFE units and 2 to 5 mol% of PAVE units with respect to all the monomer units.
The content of PAVE units in the polymer (2) is preferably 2.1 mol% or more, more preferably 2.2 mol% or more, based on all the monomer units.
The fact that the polymer (2) does not have polar functional groups means that the number of polar functional groups possessed by the polymer is less than 500 per ^{1 × 10 6 carbon atoms constituting the polymer main chain.} Means that The number of polar functional groups is preferably 100 or less, more preferably less than 50. The lower limit of the number of polar functional groups is usually 0.

The polymer (2) may be produced by using a polymerization initiator, a chain transfer agent, or the like that does not generate a polar functional group as a terminal group of the polymer chain, and the F polymer having a polar functional group is fluorinated. May be manufactured. Examples of the fluorination treatment method include a method using fluorine gas (see JP-A-2019-194314).

This powder is a powder containing an F polymer, and the amount of the heat-meltable F polymer in the powder is preferably 80% by mass or more, more preferably 100% by mass.
The D50 of this powder is preferably 50 μm or less, more preferably 20 μm or less, and even more preferably 8 μm or less. The D50 of this powder is preferably 0.1 μm or more, more preferably 0.3 μm or more, and even more preferably 1 μm or more. The D90 of this powder is preferably less than 100 μm, more preferably 90 μm or less. If D50 and D90 of the present powder are in such a range, the surface area thereof becomes large, and the dispersibility of the present powder is likely to be further improved.

This powder may contain other resins or inorganic substances different from the F polymer.
Specific examples of other resins include aromatic polymers such as aromatic polyimides, aromatic maleimides, styrene elastomers, and aromatic polyamic acids.
Specific examples of inorganic substances include silica.
This powder may form a core-shell structure having an F polymer as a core and a resin or an inorganic compound other than the F polymer as a shell, and the F polymer as a shell and a resin or an inorganic compound other than the F polymer as a core. It may form a core-shell structure.
The content of F powder in this dispersion is preferably 5% by mass or more, more preferably 10% by mass or more. The content of the F powder is preferably 60% by mass or less, more preferably 40% by mass or less.

In this method, the dispersion liquid in which the powder is dispersed in a dispersion medium is applied onto the substrate. The dispersion medium is preferably degassed from the viewpoint of reducing the uniformity of the component distribution of the molded product and suppressing voids.
The dispersion medium is a liquid, preferably a low-viscosity liquid or a high-viscosity liquid, and more preferably a low-viscosity liquid. The dispersion medium may consist of one liquid or may be a mixture of a plurality of liquids.

The low-viscosity liquid is a liquid compound having a viscosity at 25 ° C. of more than 0 mPa · s and 10 mPa · s or less and does not react with an F polymer and a different resin. The boiling point of the low-viscosity liquid is preferably 75 ° C. or higher, more preferably 100 ° C. or higher. The boiling point of the low-viscosity liquid is preferably 300 ° C. or lower, more preferably 250 ° C. or lower.
The low-viscosity liquid may be water or a non-aqueous dispersion medium. As the non-aqueous dispersion medium, amides, ketones or esters are preferable, and N-methyl-2-pyrrolidone, γ-butyrolactone, cyclohexanone or cyclopentanone are more preferable.

Highly viscous liquids are liquid compounds having a viscosity at 25 ° C. of more than 10 mPa · s and do not react with F-polymers and different resins. The viscosity of the highly viscous liquid is preferably 200 mPa · s or less. The boiling point of the highly viscous liquid is preferably 100 ° C. or higher. The boiling point of the highly viscous liquid is preferably 350 ° C. or lower, more preferably 300 ° C. or lower.
The highly viscous liquid is preferably glycol, glycol ether or glycol acetate, more preferably glycol monoalkyl ether, glycol monoaryl ether, glycol monoalkyl ether acetate or glycol monoaryl ether acetate, and even more preferably glycol monoalkyl ether.
Specific examples of the highly viscous liquid include ethylene glycol mono-2-ethylhexyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, dipropylene glycol monobutyl ether, triethylene glycol monomethyl ether, tripropylene glycol monobutyl ether, and propylene. Glycol monophenyl ether, diethylene glycol monoethyl ether acetate or diethylene glycol monobutyl ether acetate can be mentioned.

The content of the dispersion medium in the dispersion is preferably 30% by mass or more. The content of the dispersion medium is preferably 90% by mass or less, more preferably 80% by mass or less.
The solid content in the dispersion is preferably 20% by mass or more, more preferably 30% by mass or more, with the total mass of the dispersion as 100%. Further, from the viewpoint of dispersibility of the dispersion liquid, the solid content is preferably 60% by mass or less, more preferably 50% by mass or less.
The amount of solid content in the dispersion liquid means the total amount of substances that form solid content in the molded product formed from the dispersion liquid. For example, when the dispersion liquid contains an F polymer and an inorganic filler and an aromatic polymer described later, the total content of these components is the solid content in the dispersion liquid.

The dispersion liquid is a liquid containing the present powder, and is a liquid composition in which the present powder is dispersed.
The dispersion liquid may contain a third component other than the present powder. As an example of the third component, the inorganic filler is used from the viewpoint of improving the electric properties of the laminate and the low linear expansion property of the layer containing the F polymer in the laminate, and the surface activity is selected from the viewpoint of improving the dispersion stability and the handleability. Examples of the agent include aromatic polymers from the viewpoint of improving the peel strength and processability of the laminate.

The inorganic filler is preferably a nitride filler or an inorganic oxide filler, and is preferably a boron nitride filler, a beryllia filler (a filler of an oxide of beryllium), a silicate filler (silica filler, a wollastonite filler, a talc filler, or a steatite filler). ), Metal oxide fillers such as cerium oxide, aluminum oxide, magnesium oxide, zinc oxide or titanium oxide are more preferable, silica fillers, steatite fillers and boron nitride fillers are more preferable, and silica fillers are particularly preferable.
The silica content in the silica filler is preferably 50% by mass or more, more preferably 75% by mass or more. The silica content is preferably 100% by mass or less, more preferably 90% by mass or less.

It is preferable that at least a part of the surface of the inorganic filler is surface-treated. Examples of the surface treatment agent used for such surface treatment include polyhydric alcohols such as trimethylolethane, pentaeristol or propylene glycol, saturated fatty acids such as stearic acid and lauric acid, esters thereof, alkanolamines, trimethylamines and amines such as triethylamine. , Paraffin wax, silane coupling agent, silicone, polysiloxane and the like.
The silane coupling agent is 3-aminopropyltriethoxysilane, vinyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane or 3-isocyanate. A silane coupling agent having a functional group such as propyltriethoxysilane is preferable.
When the inorganic filler is surface-treated with a silane coupling agent having a functional group, voids are less likely to occur in the layer containing the F polymer in the present laminate, and the present laminate tends to have excellent water resistance. In addition, the inorganic filler is not easily peeled off from the layer containing the F polymer.

The average particle size of the inorganic filler, D50, is preferably 30 μm or less, more preferably 20 μm or less. The average particle size is preferably 0.1 μm or more, more preferably 1 μm or more.
When the present dispersion contains an inorganic filler, the D50 of the inorganic filler is preferably 10 μm or more. In this case, voids are less likely to occur in the layer containing the F polymer in the present laminate, and the present laminate tends to have excellent water resistance. Further, since the surface area of the inorganic filler is small, resistance at the interface with the F polymer is unlikely to occur, and the laminated body tends to have excellent electrical characteristics.
The shape of the inorganic filler may be granular, needle-shaped (fibrous), or plate-shaped. Specific shapes of the inorganic filler include spherical, scaly, layered, leafy, apricot kernel, columnar, chicken crown, equiaxed, leafy, mica, block, flat plate, wedge, rosette, and mesh. The shape and the prismatic shape are mentioned, and a spherical shape or a scaly shape is preferable.
Further, in addition to the above-mentioned shape, the above-mentioned inorganic filler may have various shapes such as a plate shape, a hollow shape, and a honeycomb shape.
When a hollow filler is used, the hollow ratio (average value of the volume ratio of the voids per particle) is preferably 40 to 80%.
The particle strength of the hollow filler is preferably 20 MPa or more. The particle strength is the particle strength when the residual ratio of the hollow filler after pressure pressing is 50%. The particle strength can be calculated from the apparent density of the hollow filler and the apparent density of the pellets obtained by pressure-pressing the hollow filler.

As the inorganic filler, one kind of inorganic filler may be used alone, or two or more kinds of inorganic fillers may be used in combination. In the latter case, it is preferable to use at least a silica filler. Further, in the latter case, it is preferable to use a hollow filler and a non-hollow filler in combination.
Suitable specific examples of the inorganic filler are silica filler ("Admafine" series manufactured by Admatex Co., Ltd.) and zinc oxide surface-treated with an ester such as propylene glycol dicaprate ("FINEX" manufactured by Sakai Chemical Industry Co., Ltd.). Series, etc.), Spherical molten silica filler (Denka's "SFP" series, etc.), Rutyl-type titanium oxide filler coated with polyhydric alcohol and inorganic substances (Ishihara Sangyo's "Typake" series, etc.), Alkyl Rutyl-type titanium oxide filler surface-treated with silane ("JMT" series manufactured by Teika Co., Ltd.), steatite filler ("BST" series manufactured by Nippon Tarku Co., Ltd.), boron nitride filler ("UHP" manufactured by Showa Denko Co., Ltd.) Series, Denka's "HGP" series, "GP" series, etc.).

When the dispersion liquid contains an inorganic filler, the content thereof is preferably 1% by mass or more, preferably 5% by mass or more. The content is preferably 40% by mass or less, and preferably 30% by mass or less. The mass ratio of the content of the inorganic filler to the content of the F polymer in this dispersion is preferably 0.5 or more, more preferably 0.7 or more. The mass ratio is preferably 1.5 or less, more preferably 1.2 or less. In this case, the dispersion stability of the present dispersion is more likely to be improved, and the electrical characteristics of the present laminate are more likely to be improved.

The surfactant is preferably a nonionic surfactant.
The hydrophilic moiety of the surfactant preferably has an oxyalkylene group or an alcoholic hydroxyl group.
The oxyalkylene group may be composed of one kind or two or more kinds. In the latter case, different types of oxyalkylene groups may be randomly arranged or may be arranged in blocks.
The oxyalkylene group is preferably an oxyethylene group.

The hydrophobic moiety of the surfactant preferably has an acetylene group, a polysiloxane group, a perfluoroalkyl group or a perfluoroalkenyl group.
As the surfactant, a glycol-based surfactant, an acetylene-based surfactant, a silicone-based surfactant or a fluorine-based surfactant is preferable, and a silicone-based surfactant is more preferable.
As the nonionic surfactant, one kind may be used, or two or more kinds may be used. When two kinds of nonionic surfactants are used, the nonionic surfactants are preferably a silicone-based surfactant and a glycol-based surfactant.
The fluorine-based surfactant is preferably a fluorine-based surfactant having a hydroxyl group, particularly an alcoholic hydroxyl group or an oxyalkylene group, and a perfluoroalkyl group or a perfluoroalkenyl group.
Specific examples of such surfactants include the "Futergent" series (Futtergent manufactured by Neos Co., Ltd. is a registered trademark), the "Surflon" series (Surflon manufactured by AGC Seimi Chemical Co., Ltd. is a registered trademark), and the "Mega Fuck" series ( DIC Co., Ltd. Mega Fvck is a registered trademark), "Unidyne" series (Daikin Kogyo Co., Ltd. Unidyne is a registered trademark), "BYK-347", "BYK-349", "BYK-378", "BYK-3450" , "BYK-3451", "BYK-3455", "BYK-3456" (manufactured by Big Chemie Japan), "KF-6011", "KF-6043" (manufactured by Shin-Etsu Chemical Co., Ltd.), "Tergitol" series (manufactured by Shin-Etsu Chemical Co., Ltd.) "Tergitol TMN-100X" manufactured by Dow Chemical Co., Ltd., etc. Tergitol is a registered trademark).
When the present dispersion contains a surfactant, the content thereof is preferably 1 to 15% by mass. In this case, the affinity between the components is increased, and the dispersion stability of the present dispersion is more likely to be improved.

As the aromatic polymer, aromatic polyimide, aromatic polyamideimide, aromatic maleimide, aromatic elastomer (styrene elastomer and the like), aromatic polyamic acid or polyphenylene ether are preferable, and aromatic polyimide or aromatic polyamic acid is more preferable. The aromatic polyimide may be thermoplastic or thermosetting. The thermoplastic polyimide means a polyimide that has been imidized and does not undergo a further imidization reaction.

Specific examples of aromatic polyimides include "Neoprim (registered trademark)" series (manufactured by Mitsubishi Gas Chemical Company), "Spixeria (registered trademark)" series (manufactured by Somar), and "Q-PILON (registered trademark)" series ( PI Technology Research Institute), "WINGO" series (Wingo Technology), "Toamide (registered trademark)" series (T & K TOKA), "KPI-MX" series (Kawamura Sangyo), "Yupia (" Registered trademark) -AT "series (manufactured by Ube Industries, Ltd.) can be mentioned.
Specific examples of the aromatic polyamide-imide include "HPC-1000" and "HPC-2100D" (both manufactured by Showa Denko Materials Co., Ltd.).
When the present dispersion contains an aromatic polymer, the content thereof is preferably 1 to 30% by mass, more preferably 5 to 20% by mass. In this case, the peel strength and UV processability of the laminated body are likely to be improved.

The dispersion liquid may contain non-heat-meltable polytetrafluoroethylene (hereinafter, also referred to as PTFE) in addition to the third component. In this case, the physical properties based on the non-heat-meltable PTFE are well developed, and the present laminate tends to have excellent electrical characteristics. Further, when the layer containing the F polymer in the present laminate further contains the inorganic filler and the non-heat-meltable PTFE, the non-heat-meltable PTFE is partially fibrillated when the layer containing the F polymer and the substrate are heated and compressed. It is preferable that the inorganic filler is highly supported and the powder falling is easily suppressed.
The non-thermally meltable PTFE means a PTFE that does not have a temperature at which the melting flow rate is 1 to 1000 g / 10 minutes under the condition of a load of 49 N. The non-heat-meltable PTFE may be a homopolymer of TFE, and in addition to the TFE unit, a trace amount of PAVE, hexafluoropropylene (hereinafter, also referred to as “HFP”) or fluoroalkyl ether (hereinafter, hereinafter, “HFP”) may be used. It may be a modified PTFE such as a copolymer having a unit based on (also referred to as “FAE”).
This dispersion preferably contains non-heat-meltable PTFE as a non-heat-meltable PTFE powder. The D50 of such powder is preferably 0.1 to 1 μm.
When the present dispersion contains non-heat-meltable PTFE, the content of the non-heat-meltable PTFE powder is preferably 1% by mass or more, more preferably 10% by mass or more. The content is preferably 60% by mass or less, more preferably 40% by mass or less. The ratio of the content of the non-heat-meltable PTFE powder in the present dispersion is preferably 1 or more, more preferably 3 or more, with the content of the F powder being 1. The ratio is preferably 100 or less. In this case, the laminated body tends to have excellent electrical characteristics and water resistance.

The present dispersion may also contain a silane coupling agent separately from the viewpoint of the adhesiveness of the layer containing the F polymer. In this case, the present dispersion tends to be excellent in dispersion stability and film forming property. Further, when the dispersion liquid contains the inorganic filler, the F powder and the inorganic filler are more firmly bonded to each other, and as a result, the inorganic filler is less likely to fall off from the laminate. Examples of the silane coupling agent include compounds similar to the silane coupling agent used for the surface treatment of the inorganic filler.

When the present dispersion contains a silane coupling agent, the content thereof is preferably 0.1% by mass or more, more preferably 1% by mass or more. The content is preferably 20% by mass or less, more preferably 10% by mass or less.
When the present dispersion contains a silane coupling agent, the ratio of the content of the silane coupling agent is preferably 0.01 or more, more preferably 0.05 or more, with the content of the F powder being 1. The ratio of the content of the silane coupling agent is preferably 0.3 or less, more preferably 0.1 or less, with the content of the F powder being 1.
When the content of the silane coupling agent is within the above range, the present dispersion tends to have excellent dispersion stability.
Preferred silane coupling agents include the silane coupling agent used for the surface treatment of the above-mentioned inorganic filler.

In this method, the dispersion liquid is applied onto a substrate and dried to form a coating film.
Examples of the substrate include a metal substrate and a resin substrate.
The metal substrate is preferably a metal foil. If the metal foil is processed, the molded product of the present invention can be suitably used as a printed circuit board. Examples of the metal constituting the metal foil include copper, copper alloy, stainless steel, nickel, nickel alloy, aluminum, aluminum alloy, titanium, and titanium alloy.
As the metal foil, a copper foil is preferable, a rolled copper foil having no distinction between the front and back sides or an electrolytic copper foil having a distinction between the front and back sides is more preferable, and a rolled copper foil is further preferable. Since the rolled copper foil has a small surface roughness, transmission loss can be reduced even when the laminated body is processed into a printed circuit board. Further, the rolled copper foil is preferably used after being immersed in a hydrocarbon-based organic solvent to remove rolling oil.
The ten-point average roughness of the surface of the metal foil is preferably 0.01 to 0.05 μm.

Further, the metal substrate may be a metal foil with a carrier including two or more layers of metal foil. Examples of the metal foil with a carrier include a copper foil with a carrier having a thickness of 10 to 35 μm and an ultrathin copper foil having a thickness of 2 to 5 μm laminated on the carrier copper foil via a release layer. Be done.
By peeling off only the carrier copper foil of the copper foil with a carrier, a laminate having an ultrathin copper foil can be easily formed. By using this laminate, it is possible to form a fine pattern by using an ultrathin copper foil layer as a plating seed layer by an MSAP (modified semi-additive) process.
As the release layer, a metal layer containing nickel or chromium or a multilayer metal layer in which the metal layers are laminated is preferable from the viewpoint of heat resistance. With such a peeling layer, the carrier metal foil can be easily peeled from the ultrathin metal foil even after a step of 300 ° C. or higher.
Specific examples of the metal foil with a carrier include the trade name "FUTF-5DAF-2" manufactured by Fukuda Metal Foil Powder Industry Co., Ltd.

As the resin substrate, a layer containing polyimide is preferable, and a polyimide film is more preferable.
As the polyimide, a polyimide obtained by reacting a diamine with a carboxylic acid dianhydride to synthesize a polyamic acid and imidizing the polyamic acid by a thermal imidization method or a chemical imidization method is preferable. As the polyimide, aromatic polyimide is particularly preferable.
The surface of the substrate may be surface-treated with a silane coupling agent or the like.

This dispersion is applied onto the substrate and dried to remove the dispersion medium to form a coating film containing an F polymer. The coating film may be formed on at least one side of the surface of the base material, the coating film may be formed on only one side of the base material, or the coating film may be formed on both sides of the base material. Further, drying may be carried out until the dispersion medium is completely removed to form a coating film containing no dispersion medium, or drying may be carried out until most of the dispersion medium is removed to form a coating film containing a trace amount of the dispersion medium. You may. In the latter coating film formation, it is preferable to remove 90% by mass or more of the dispersion medium contained in the present dispersion liquid.
The coating film preferably contains an unmelted F polymer, and more preferably formed by packing the unmelted present powder.

When applying this dispersion, the spray method, roll coat method, spin coat method, gravure coat method, micro gravure coat method, gravure offset method, knife coat method, kiss coat method, bar coat method, die coat method, fountain Mayer bar method. , The application method of the slot die coating method can be used.

The temperature for removing the dispersion medium is preferably a temperature below the melting temperature of the F polymer and below the boiling point of the dispersion medium, preferably 100 ° C. or less below the melting temperature of the F polymer and 10 ° C. to 100 ° C. below the boiling point of the dispersion medium. More preferred. For example, when an F polymer having a melting temperature of 300 ° C. and N-methyl-2-pyrrolidone having a boiling point of about 200 ° C. are used, the temperature for removing the dispersion medium is preferably 150 ° C. or lower, more preferably 100 to 100 ° C. It is 120 ° C. From the viewpoint of forming a coating film having excellent smoothness, it is preferable to blow air onto the surface of the formed coating film when removing the dispersion medium.

The formed coating film is further heated, and the F polymer is melt-fired to form a layer containing the F polymer (hereinafter, also referred to as an F layer). The F polymer in the F layer may be completely melt-fired or partially melt-fired.
The thickness of the F layer is preferably 1 μm or more, more preferably 10 μm or more, still more preferably 50 μm or more. The upper limit of the thickness is preferably 300 μm or less, more preferably 100 μm or less, still more preferably 50 μm or less.
In this range, the F layer having excellent crack resistance can be easily formed. The peel strength between the F layer and the base material is preferably 10 N / cm or more, more preferably 15 N / cm or more. The peel strength is preferably 100 N / cm or less.

The F layer is formed through the steps of applying the dispersion liquid and heating as described above, but these steps may be repeated twice or more. For example, the present dispersion may be applied to the surface of the base material and heated to form the F layer, and the present dispersion may be further applied to the surface of the F layer and heated to form the second F layer. .. Further, at the stage where the present dispersion is applied to the surface of the base material and heated to remove the liquid dispersion medium, the present dispersion may be further applied to the surface and heated to form the F layer.

In this method, the coating film or the F layer and the substrate are heat-compressed at least in any process from the formation of the coating film to the formation of the F layer. The heat compression is preferably performed after the formation of the coating film or the formation of the F layer.
As described above, the formation of the coating film is to dry the dispersion liquid applied on the substrate to remove the dispersion medium and form the coating film containing the F polymer.
Further, the formation of the F layer is, as described above, further heating the coating film to melt-fire the F polymer to form the F layer, until the cooling after the firing is completed. Cooling after melt firing may be either forced cooling with cold air or cold water, or natural cooling left at around room temperature, but the stage when the temperature of the laminate having the F layer drops to the ambient temperature is regarded as the completion of cooling.
The heat compression is preferably performed when the F layer is formed, preferably after the F layer is formed, and preferably before the cooling is completed, and more preferably immediately after the F polymer is fired.
When the F layer is formed by repeating the steps of applying the dispersion liquid and heating twice or more as described above, heat compression may be performed after the first application, or after the second application and heating. It may be performed after any of the steps. Further, heat compression may be performed sequentially after each step, or several steps may be performed without heat compression. Heat compression may be performed after all the steps of applying and heating the dispersion liquid.

The heat compression is, for example,
(1) The stage immediately after the dispersion liquid is dried and the coating film is formed (2) The stage after the coating film is formed and before the coating film is further heated to form the F layer.
(3) At the stage where the coating film is further heated and the F polymer is melt-fired to form the F layer.
(4) The stage until the F layer formed by melting and firing the F polymer is cooled.
It is preferable to carry out at any stage of. The temperature of the coating film in (1) above is preferably the temperature at which the dispersion medium is removed. Further, in the step (2) above, after the coating film is formed, the coating film may be cooled once, or after the coating film is formed, it may be further heated without being cooled. The heat compression is more preferably performed at the step (3) or (4) above, and further preferably at the step (4). The heat compression may be performed in a plurality of the above steps.

The temperature of heat compression is preferably higher than the glass transition temperature of the F polymer, and more preferably 30 ° C. or higher than the glass transition temperature. The temperature of heat compression is preferably 100 ° C. higher than the melting temperature of the F polymer, more preferably lower than the melting temperature, and even more preferably 100 ° C. or lower than the melting temperature. The temperature of heat compression is preferably a temperature higher than the glass transition temperature of the F polymer and 100 ° C. or more lower than the melting temperature of the F polymer.

The heat compression is preferably performed in an atmosphere of atmospheric pressure to reduced pressure, and more preferably performed in an atmosphere of atmospheric pressure.
The pressure for heat compression is preferably 0.2 MPa or more, more preferably 0.5 MPa or more. The pressure is preferably 10 MPa or less, more preferably 5 MPa or less.

The heat compression method is a method of passing the coating film or the F layer and the substrate between a pair of heated rolls at any stage from the formation of the coating film to the formation of the F layer, the coating film or the F layer. A method of blowing hot air while passing the substrate through a pair of rolls, and a method of pressurizing the coating film or the F layer and the substrate by a heated press.
As a method of passing between a pair of rolls, it is preferable to use a roll press machine. As the pair of rolls, a pair of metal rolls may be used, or a metal roll and a rubber roll may be used. The linear pressure applied between the pair of rolls is preferably 1 to 20 tf / m, more preferably 2 to 10 tf / m. The temperature of the roll is preferably 70 ° C. or higher than the melting point of the F polymer, and more preferably 50 ° C. or higher than the melting point of the F polymer. The temperature of the roll is preferably 70 ° C. or higher, which is 70 ° C. lower than the melting point of the F polymer, and more preferably 50 ° C. or higher, which is 50 ° C. lower than the melting point of the F polymer. The temperature of the roll is preferably 250 ° C. or higher, more preferably 300 ° C. or higher. The temperature of the roll is preferably 370 ° C or lower, more preferably 350 ° C or lower.
When the F layer and the substrate are passed between the pair of rolls, a release film is placed between the surface of the F layer and the roll, or the roll is placed, from the viewpoint of suppressing the adhesion of the F layer to the roll. It is preferable to surface-treat the surface with a mold release agent. It is preferable that the release film is in contact with the F layer only on the pressurized surface of the roll and is peeled off when the F layer is separated from the roll.
The thickness of the release film is preferably 50 to 150 μm.
Examples of the release film include a polyimide film, and specific examples thereof include "Apical NPI" (manufactured by Kaneka Corporation), "Kapton EN" (Toray DuPont), and "UPIREX S (Ube Industries, Ltd.)".

When the thickness of the coating film or F layer before heat compression is 10 to 300 μm, the thickness of the coating film or F layer after heat compression is preferably 5 to 200 μm.
By the above heat compression, the ratio of the thickness of the coating film or the F layer after the heat compression to the thickness of the coating film or the F layer before the heat compression is preferably 0.1 to 0.8. For example, the ratio of the thickness of the coating film after heat compression to the thickness of the coating film before heat compression is 0.1 to 0.8, or the thickness of the F layer before heat compression is after heat compression. The thickness ratio of the F layer is preferably 0.1 to 0.8.
Further, according to this method, even if the thickness of the F layer is increased, the powder of the present powder or the inorganic filler is suppressed from falling off in the obtained laminate, so that the thickness of the F layer after heat compression can be adjusted. Can be thickened. A laminate with a thick F layer has improved electrical characteristics and water resistance. From this point of view, the thickness of the F layer after heat compression is preferably 40 μm or more. The thickness of the F layer after heat compression is usually 200 μm or less.

When a laminate having a layer containing an F polymer is produced by applying, drying, and heating a dispersion liquid containing the powder of the F polymer, the powder once accumulates in the state of the coating film, so that voids are generated between the powders. The coating film was further heated to melt the powder and form a layer, but at this time, it was difficult to completely fill the voids. However, it is considered that the voids in the laminate obtained by the production method having the heat compression step as in the above method are crushed and the voids in the layer are reduced.

The present laminated body is obtained by the above-mentioned method.
The porosity of the F layer in this laminated body is preferably 5% or less, more preferably 4% or less. The porosity is preferably 0.01% or more, more preferably 0.1% or more. The void ratio is determined by image processing to determine the void portion of the F layer from the SEM photograph of the cross section of the molded product observed using a scanning electron microscope (SEM), and the area occupied by the void portion is the area occupied by the F layer. It is the ratio (%) divided by the area. The area occupied by the void portion is obtained by approximating the void portion to a circle.
The present laminated body may be a laminated body having an F layer on one side of the substrate and the substrate, or may be a laminated body having an F layer on both sides of the substrate and the substrate.

The surface of the F layer of the present laminate may be further surface-treated to improve its adhesiveness. Surface treatment includes corona discharge treatment, plasma treatment such as atmospheric pressure plasma discharge treatment or vacuum plasma discharge treatment, plasma graft polymerization treatment, electron beam irradiation, light beam irradiation treatment such as Exima UV light irradiation, itro treatment using flame, metallic sodium. Wet etching treatment using the above can be mentioned, and vacuum plasma discharge treatment is preferable.
The vacuum plasma discharge treatment can be carried out using a known device. From the viewpoint of processing efficiency, the vacuum plasma discharge treatment is preferably a glow discharge treatment in which continuous discharge is performed at a gas pressure of 0.1 to 1330 Pa, preferably 1 to 266 Pa, that is, a so-called low temperature plasma treatment. Stable glow discharge can be performed by applying a power of 10 W to 100 kW at a frequency of 10 kHz to 2 GHz between the discharge electrodes under such gas pressure. The discharge power density of the vacuum plasma discharge process is preferably ^{5 to 400 W · min / m 2.} Examples of the gas used for the vacuum plasma discharge treatment include helium gas, neon gas, argon gas, nitrogen gas, oxygen gas, carbon dioxide gas, hydrogen gas, air, and water vapor. These gases may be used as a mixture of two or more. As the gas, an argon gas, a carbon dioxide gas, an oxygen gas or a mixed gas of nitrogen gas and hydrogen gas is preferable, and a mixed gas of argon gas and hydrogen gas is more preferable, from the viewpoint of improving the adhesion strength. The gas flow rate during the treatment is preferably 500 to 10,000 sccm.

When this laminated body is further laminated with another layer, the configuration thereof is, for example, a metal substrate / F layer / another base material layer / F layer / metal substrate, a metal substrate layer / another base material layer / F layer. / Other base material layer / Metal substrate layer and the like. Each layer may further contain a glass cloth or filler.
This laminate is useful as antenna parts, printed substrates, aircraft parts, automobile parts, sports equipment, food industry supplies, paints, cosmetics, etc. Specifically, wire covering materials such as aircraft electric wires, electricity. Insulating tape, insulating tape for oil drilling, materials for printed substrates, precision filtration membranes, ultrafiltration membranes, reverse osmosis membranes, ion exchange membranes, separation membranes such as dialysis membranes or gas separation membranes, lithium secondary batteries or fuels. Electrode binders for batteries, copy rolls, furniture, automobile dash boats, covers for home appliances, load bearings, sliding shafts, valves, bearings, gears, cams, sliding members such as belt conveyors or food transport belts, shovels. It is useful as a tool for shavings, cuttings, saws, boilers, hoppers, pipes, ovens, baking molds, chutes, dies, toilet bowls, and container covering materials.

As described above, according to this method, it is possible to improve the adhesiveness between the F layer and the substrate, to have excellent water resistance, peel strength, etc., and to be resistant to deterioration, in other words, to produce a highly reliable laminated body.

Although the present method has been described above, the present invention is not limited to the configuration of the above-described embodiment.
For example, this method may additionally have any other step in the configuration of the above embodiment, or may be replaced with any step that produces the same action. Further, in the configuration of the above embodiment, the present laminated body may be added with any other configuration or may be replaced with any configuration exhibiting the same function.

Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited thereto.
1. 1. Preparation of each ingredient [Powder]
Powder 1: F-polymer 1 containing 98.0 mol%, 0.1 mol%, 1.9 mol% of TFE units, NAH units and PPVE units in this order and having an oxygen-containing polar group (melting temperature: 300 ° C., Powder consisting of glass transition point: 85 ° C. (D50: 2.0 μm, 98% particle size: 4.9 μm)
Powder 2: Powder made of non-heat-meltable PTFE (D50: 0.3 μm)

[Inorganic filler]
Filler 1: Approximately spherical silica filler (D50: 0.4 μm, 98% granules) surface-treated with vinyltrimethoxysilane (hereinafter, also referred to as vinylsilane), which is composed of silicon oxide and has a specific surface area of 7 m ^{2 / g.} Diameter: 1.0 μm)
Filler 2: A substantially spherical silica filler (D50: 0.4 μm, 98% particle size: 1.0 μm) which is composed of silicon oxide and has a specific surface area of 7 m ^{2 / g and is not surface-treated.}
Filler 3: A substantially spherical silica filler (D50: 16 μm, 98% particle size: 20 μm) surface-treated with vinylsilane, which is composed of silicon oxide and has a specific surface area of 3 m ^{2 / g.}

[Non-aqueous solvent]
NMP: N-methyl-2-pyrrolidone [surfactant]
Surfactant 1: Copolymer of (meth) acrylate having perfluoroalkenyl group and (meth) acrylate having hydroxyl group and oxyethylene group [varnish of other polymer]
Varnish 1: Varnish in which thermoplastic polyimide (PI1) is dissolved in NMP

2. 2. Production example of dispersion liquid (Example 1)
First, powder 1, varnish 1, surfactant 1 and NMP were put into a pot, and then zirconia balls were put into the pot. Then, the pot was rolled at 150 rpm for 1 hour to prepare a liquid composition.
Next, after the filler 1, the surfactant 1 and the NMP were put into the pot, the zirconia balls were put into the pot. Then, the pot was rolled at 150 rpm for 1 hour to prepare a liquid composition.
Then, after putting both liquid compositions into the pot, zirconia balls were put into the pot. Then, the pot is rolled at 150 rpm for 1 hour to powder 1 (11 parts by mass), filler 1 (11 parts by mass), PI1 (7 parts by mass), surfactant 1 (4 parts by mass) and NMP (67 parts by mass). A dispersion liquid 1 having a viscosity of 400 mPa containing the part) was obtained.

(Example 2)
Powder 1 (11 parts by mass), filler 1 (11 parts by mass), surfactant 1 (4 parts by mass) and NMP (4 parts by mass) in the same manner as in Example 1 except that the amount of NMP was changed without using varnish 1. A dispersion liquid 2 having a viscosity of 400 mPa containing 74 parts by mass) was obtained.
(Example 3)
Powder 1 (11 parts by mass), filler 2 (11 parts by mass), PI1 (7 parts by mass), surfactant 1 (4 parts by mass) in the same manner as in Example 1 except that the filler 1 was changed to the filler 2. And NMP (67 parts by mass) and a dispersion liquid 3 having a viscosity of 700 mPa · s were obtained.

(Example 4)
Powder 1 (11 parts by mass), filler 3 (11 parts by mass), PI1 (7 parts by mass), surfactant 1 (4 parts by mass) in the same manner as in Example 1 except that the filler 1 was changed to the filler 3. And NMP (67 parts by mass) and a dispersion liquid 4 having a viscosity of 400 mPa were obtained.

(Example 5)
Powder 1 (2 parts by mass), powder 2 (9 parts by mass), in the same manner as in Example 1 except that 11 parts by mass of powder 1 was changed to 2 parts by mass of powder 1 and 9 parts by mass of powder 2. A dispersion 5 having a viscosity of 500 mPa containing filler 3 (11 parts by mass), PI1 (7 parts by mass), surfactant 1 (4 parts by mass) and NMP (67 parts by mass) was obtained.

3. 3. Example of manufacturing of laminated body (manufacturing of laminated body 1)
The dispersion liquid 1 was applied to the surface of a long copper foil having a thickness of 18 μm using a bar coater. Next, the copper foil coated with the dispersion liquid 1 was passed through a drying oven at 120 ° C. for 5 minutes and dried by heating to obtain a coating film. The thickness of the formed coating film was 12 μm. Immediately after drying, until the coating film is cooled to 25 ° C., the coating film is heated to a temperature of 150 ° C. and a pressure of 0.6 MPa by hot pressing by roller pressing in an atmosphere of atmospheric pressure, and the thickness of the coating film becomes 8 μm. Heat compressed to. Then, the coating film was heated at 380 ° C. for 3 minutes in a nitrogen oven. As a result, a laminate 1 having a copper foil and an F layer having a thickness of 7 μm as a molded product containing a melt-fired product of powder 1 and filler 1 and PI1 on the surface thereof was produced. It was confirmed that the voids in the coating film decreased before and after heat compression.

(Manufacturing of laminated body 2)
A coating film was obtained on the surface of the copper foil in the same manner as in the laminated body 1. The thickness of the formed coating film was 15 μm. Then, the coating film was heated at 380 ° C. for 3 minutes in a nitrogen oven to obtain an F layer having a thickness of 12 μm, which contained a copper foil and a melt-fired product of powder 1 and filler 1 and PI1 on the surface thereof. .. Then, immediately after heating, until the F layer is cooled to 25 ° C., the F layer is hot-pressed in a vacuum atmosphere at a temperature of 330 ° C. and a pressure of 0.2 MPa using a vacuum press machine to reach 8 μm. It was heated and compressed to obtain a laminated body 2. Before and after heat compression, a decrease in the voids in the F layer was confirmed.

(Manufacturing of laminated body 3)
The laminate 3 was manufactured in the same manner as the laminate 2 except that the dispersion 1 was changed to the dispersion 2 and the hot press conditions were changed to a temperature of 330 ° C. and 0.6 MPa. It was confirmed that the voids in the F layer decreased before and after the heat compression.

(Manufacturing of laminated body 4)
The laminate 4 was manufactured in the same manner as the laminate 3 except that the conditions of the hot press were changed to a temperature of 330 ° C. and 1.0 MPa and the F layer was heated and compressed until the temperature became 5 μm. It was confirmed that the voids in the F layer decreased before and after the heat compression.

(Manufacturing of laminated body 5)
The laminate 5 was manufactured in the same manner as the laminate 3 except that the conditions of the hot press were changed to a temperature of 380 ° C. and 0.6 MPa. It was confirmed that the voids in the F layer decreased before and after the heat compression.

(Manufacturing of laminated body 6)
The laminate 6 was manufactured in the same manner as the laminate 3 except that the heat press was not performed.

(Manufacturing of laminated body 7)
The laminated body 7 was manufactured in the same manner as the laminated body 1 except that the dispersion liquid 1 was changed to the dispersion liquid 3. Before and after heat compression, a decrease in the voids in the F layer was confirmed.

(Manufacturing of laminated body 8)
The laminated body 8 was manufactured in the same manner as the laminated body 1 except that the dispersion liquid 1 was changed to the dispersion liquid 4. Before and after heat compression, a decrease in the voids in the F layer was confirmed.

(Manufacturing of laminated body 9)
The laminated body 8 was manufactured in the same manner as the laminated body 1 except that the dispersion liquid 1 was changed to the dispersion liquid 5. Before and after heat compression, a decrease in the voids in the F layer was confirmed.

(Manufacturing of laminated body 10)
The laminated body 10 was manufactured in the same manner as the laminated body 1 except that the thickness of the F layer was changed to 100 μm.

(Manufacturing of laminated body 11)
The laminated body 11 was manufactured in the same manner as the laminated body 1 except that the thickness of the F layer was changed to 100 μm and no heat pressing was performed.

(Manufacturing of laminated body 12)
A coating film was obtained on the surface of the copper foil in the same manner as in the laminated body 1. The thickness of the formed coating film was 15 μm. Then, in a nitrogen oven, the coating film is heated at 380 ° C. for 3 minutes to have a copper foil and an F layer having a thickness of 12 μm containing a melt-fired product of powder 1 and filler 1 and PI1 on the surface thereof. A laminate was obtained. Then, immediately after heating and before the F layer was cooled to 25 ° C., the obtained laminate was passed between a pair of metal rolls at 330 ° C. in an atmosphere of atmospheric pressure. At this time, the polyimide film was sandwiched between the surface of the F layer and the metal roll as a release film and passed through the laminate. As a result, the F layer was heated and compressed to obtain a laminated body 12.
Before and after heat compression, a decrease in the porosity of the F layer was confirmed, and the porosity of the F layer was 0.1% or more and 4% or less.
The laminates 1 to 12 were evaluated for peel strength, water resistance, electrical characteristics and warpage based on the following criteria.

3. 3. Measurement and evaluation 3-1. Evaluation of Water Resistance Each laminate was etched with an aqueous solution of ferric chloride to remove the copper foil to obtain a simple substance F layer.
This F layer was pre-dried at 50 ° C. for 48 hours according to ASTM D570, and then immersed in pure water at 23 ° C. for 24 hours. The mass of the F layer before and after immersion in pure water was measured, the water absorption rate was determined based on the following formula, and the evaluation was made according to the following criteria.
Water absorption rate (%) = (mass after immersion in water-mass after pre-drying) / mass after pre-drying x 100
〇: The water absorption rate is 0.05% or less.
Δ: The water absorption rate is more than 0.05% and 0.1% or less.
X: The water absorption rate is more than 0.1%.

3-2. Evaluation of peeling strength after high-temperature and high-humidity treatment A rectangular test piece with a length of 100 mm and a width of 10 mm was cut out from each laminate and held at 85 ° C. and a relative humidity of 85% for 72 hours before testing. The copper foil and the F layer were peeled off from one end in the length direction of the piece to a position of 50 mm, and the peeled copper foil and one end of the F layer were attached to each chuck of a tensile tester (manufactured by Orientec). Next, the peel strength (N / cm) of the copper foil and the F layer in the unpeeled portion of this test piece was measured by a tensile tester and evaluated according to the following criteria.
〇: Peeling strength ≧ 10 N / cm
X: Peeling strength ≤ 10 N / cm

3-3. Evaluation of Dissipation Factor after High Temperature and High Humidity Treatment A rectangular test piece with a length of 100 mm and a width of 50 mm was cut out from each laminate and etched with an aqueous ferric chloride solution to remove the copper foil, and the F layer alone was removed. Obtained. After holding the F layer alone in an atmosphere of 85 ° C. and 85% relative humidity for 72 hours, the dielectric loss tangent (measurement frequency: 10 GHz) of the multilayer film was measured by the SPDR (split post dielectric resonance) method. It was evaluated according to the criteria of.
〇: The dielectric loss tangent is less than 0.0020.
Δ: The dielectric loss tangent is 0.0020 or more and 0.0040 or less.
X: The dielectric loss tangent is more than 0.0040.

3-4. Evaluation of Warpage after High Temperature and High Humidity Treatment A 180 mm square test piece was cut out from each laminate and held in an atmosphere of 85% relative humidity for 72 hours, and then the test piece was placed on a smooth glass surface. It was allowed to stand still and visually evaluated, and evaluated according to the following criteria.
〇: No warpage is confirmed on the test piece.
Δ: Warpage (waviness) is confirmed on the test piece, but the test piece is not curled.
X: Warpage (waviness) was confirmed on the test piece, and the test piece was curled.
The above results are shown in Table 1 below.

It should be noted that each of the laminated bodies 8 to 10 was more excellent in physical properties of the laminated body in the following points as compared with the laminated body 1.
The laminate 8 had a lower dielectric loss tangent itself and was excellent in electrical characteristics.
In the laminated bodies 9 and 10, the inorganic filler did not easily come off and was easy to handle, and the surface smoothness of the layer was also high.
The laminated body 12 had a lower water absorption rate in the evaluation of water resistance and was excellent in water resistance as compared with the laminated body 2.

As is clear from the above results, the cross section of the laminated body prepared by this method has no voids and is dense, has low water absorption, has excellent peel strength and electrical characteristics, and has little warpage. .. Therefore, the laminate obtained by this method has excellent adhesiveness to various substrates, and has excellent peel strength and water resistance.

Claims

A dispersion containing a powder of a heat-meltable tetrafluoroethylene polymer is applied onto a substrate and dried to form a coating film, and the obtained coating film is further heated to further heat the heat-meltable tetrafluoroethylene polymer. A layer containing a heat-meltable tetrafluoroethylene-based polymer that heats and compresses the coating film or the layer and the substrate in the process from the formation of the coating film to the formation of the layer. A method for producing a laminate having.
The heat-meltable tetrafluoroethylene polymer contains units based on perfluoro (alkyl vinyl ether) and has a polar functional group, or contains 2 to 5 mol% of units based on perfluoro (alkyl vinyl ether) with respect to all units. The method for producing a laminate according to claim 1, which is a polymer having no polar functional group.
The method for manufacturing a laminate according to claim 1 or 2, wherein the substrate is a copper foil or a polyimide film.
Any one of claims 1 to 3 in which the temperature of the heat compression is equal to or higher than the glass transition temperature of the heat-meltable tetrafluoroethylene-based polymer and 100 ° C. higher than the melting temperature of the heat-meltable tetrafluoroethylene-based polymer. The method for manufacturing a laminate according to the section.
The method for producing a laminate according to any one of claims 1 to 4, wherein the heat compression pressure is 0.2 MPa or more and 10 MPa or less.
The method for producing a laminate according to any one of claims 1 to 5, wherein the heat compression is performed when the layer is formed.
The ratio of the thickness of the coating film after heat compression to the thickness of the coating film before heat compression, or the thickness of the layer after heat compression to the thickness of the layer before heat compression. The method for producing a laminate according to any one of claims 1 to 6, wherein the ratio is 0.1 to 0.8.
The method for producing a laminate according to any one of claims 1 to 7, wherein the thickness of the layer after heat compression is 40 μm or more.
The method for producing a laminate according to any one of claims 1 to 8, wherein the dispersion further contains an inorganic filler.
The method for producing a laminate according to any one of claims 1 to 9, wherein the dispersion further contains an inorganic filler surface-treated with a silane coupling agent.
The method for producing a laminate according to any one of claims 1 to 10, wherein the dispersion liquid contains an inorganic filler having an average particle size of 10 μm or more.
The laminate according to any one of claims 9 to 11, wherein the mass ratio of the inorganic filler to the heat-meltable tetrafluoroethylene polymer in the dispersion is 0.5 to 1.5. Manufacturing method.
The method for producing a laminate according to any one of claims 1 to 12, wherein the dispersion further contains a non-heat-meltable polytetrafluoroethylene powder.
The method for producing a laminate according to any one of claims 1 to 13, wherein the dispersion further contains an aromatic polymer.
The method for producing a laminate according to any one of claims 1 to 14, wherein the dispersion further contains a silane coupling agent.