JP2020077717A - Fluid dispersion and manufacturing method of sheet material - Google Patents

Abstract

To provide a fluid dispersion containing an acid-modified hydrocarbon-based polymer capable of forming a layer having an adhesive property and an electrical property (adhesive layer), and a manufacturing method of a sheet material having a layer having an adhesive property and an electrical property.SOLUTION: A fluid dispersion according to the present invention includes a powder containing a tetrafluoroethylene-based polymer, a thermally decomposable fluoropolymer, an acid-modified hydrocarbon-based polymer, and a solvent, and the powder is dispersed in the solvent. In a manufacturing method of a sheet material according to the present invention, the fluid dispersion is applied to the surface of a sheet base material to form a liquid coating, and the liquid coating is heated to obtain sheet material having a layer containing the semi-cured product of the powder and the acid-modified hydrocarbon-based polymer.SELECTED DRAWING: None

Description

  The present invention includes a dispersion containing a powder containing a tetrafluoroethylene-based polymer, a thermally decomposable fluoropolymer, an acid-modified hydrocarbon-based polymer and a solvent, the powder being dispersed in the solvent, and the powder and the acid-modified carbon. The present invention relates to a method for producing a sheet material having a layer containing a semi-cured product of a hydrogen-based polymer.

With the miniaturization and higher functionality of electronic devices and electric devices, there is an increasing demand for printed circuit boards in which conductor circuits are multilayered and printed circuit boards with a coverlay film. These printed boards are manufactured by thermocompression bonding the printed board and a board having an adhesive layer (adhesive sheet or coverlay film with an adhesive layer).
Acid-modified hydrocarbon-based polymers such as acid-modified polystyrene and acid-modified polyolefin are known as adhesive polymers used in compositions for forming such adhesive layers (see Patent Documents 1 and 2). If a thermosetting composition is prepared by using these adhesive polymers in combination with epoxy resin or the like, the curing rate at low temperature is high, and each constituent part of the printed board (metal wiring part such as copper or polyimide etc. It is possible to obtain a substrate having an adhesive layer that exhibits strong adhesiveness with a resin insulating layer).

International Publication No. 2018/131571 International Publication No. 2014/147903

On the other hand, due to the progress of higher frequency of electric signals on a printed circuit board, a lower dielectric constant and heat resistance of a substrate having an adhesive layer have been demanded from the viewpoint of suppressing signal propagation speed and transmission loss. In order to lower the dielectric constant of a substrate having an adhesive layer using an acid-modified hydrocarbon-based polymer to make it heat resistant, a method of further blending a material having excellent physical properties with the thermosetting composition can be mentioned. The present inventors have examined the blending of such a material, a tetrafluoroethylene-based polymer, and found that it has adhesive properties (low temperature curing property, adhesive strength, etc.), electrical properties (low dielectric constant, low dielectric loss tangent, etc.), and heat resistance. It has not been possible to obtain a substrate having an adhesive layer sufficiently containing
The present invention comprises a dispersion containing an acid-modified hydrocarbon-based polymer capable of forming a layer (adhesive layer) having adhesive properties, electrical properties and heat resistance, and adhesive properties, electrical properties and heat resistance. An object of the present invention is to provide a method for producing a sheet material having a layer.

The present invention has the following aspects.
<1> A dispersion liquid containing a powder containing a tetrafluoroethylene-based polymer, a thermally decomposable fluoropolymer, an acid-modified hydrocarbon-based polymer, and a solvent, and the powder being dispersed in the solvent.
<2> The dispersion liquid of <1>, further containing an epoxy resin.
<3> The dispersion liquid according to <1> or <2>, wherein the thermal decomposition start temperature of the thermally decomposable fluoropolymer is 250 ° C. or lower.
<4> The dispersion liquid according to any one of <1> to <3>, in which the thermally decomposable fluoropolymer has any of groups represented by the following formulas (1) to (4) in a side chain.
(1) -C (O) OCH (CH 3) OR 1
(2) -C (O) OC (-R 2) 3
_{(3) -C (O) OCH} 2 -R 3
^{(4) -C (O) OC} (-R 41) (- R 42) 2
[In the formula, R ¹ represents a polyfluoroalkyl group or a polyfluoroalkyl group containing an etheric oxygen atom, R ² represents an alkyl group or an aryl group (three R ² may be the same. R ³ represents an aryl group, R ⁴¹ represents a hydrogen atom or an alkoxy group, and R ⁴² represents an alkyl group (two R ⁴² may be the same). They may be different and may together form an alkylene group.). ]
<5> The thermally decomposable fluoropolymer is a polymer including a unit based on a compound represented by the following formula F and a unit based on a compound represented by any of the following formulas D1 to D4, <1>>-<4> dispersion liquid.
Formula F: CH ₂ = CX ^F C (O) O-Q ^F- R ^F
Formula ^{_{D1: CH 2 = CX 1 C}} (O) OCH (CH 3) OR 1
Wherein ^{_{D2: CH 2 = CX 2 C}} (O) OC (-R 2) 3
Formula ^{_{D3: CH 2 = CX 3 C}} (O) OCH 2 -R 3
Wherein ^{_{D4: CH 2 = CX 4 C}} (O) OC (-R 41) (- R 42) 2
[In the formula, X ^F represents a hydrogen atom, a chlorine atom or a methyl group, Q ^F represents a methylene group, an ethylene group, an oxyethylene group or an oxybutylene group, and X ¹ , X ² , X ³ and X ⁴ Each independently represent a hydrogen atom or a methyl group, and R ^F represents a polyfluoroalkyl group having 1 to 6 carbon atoms, a polyfluoroalkyl group having 3 to 6 carbon atoms containing an etheric oxygen atom, or 4 to 4 carbon atoms. 12 represents a polyfluoroalkenyl group, R ¹ represents a polyfluoroalkyl group or a polyfluoroalkyl group containing an etheric oxygen atom, R ² represents an alkyl group or an aryl group (three R ² are the same). R ³ represents an aryl group, R ⁴¹ represents a hydrogen atom or an alkoxy group, R ⁴² represents an alkyl group (two R ⁴² are the same). Or may be different from each other, and may together form an alkylene group.). ]
<6> The dispersion liquid according to any one of <1> to <5>, wherein the acid-modified hydrocarbon polymer is an acid-modified polyolefin.
<7> The dispersion liquid according to any one of <1> to <6>, wherein the amount of the powder contained in the dispersion liquid is smaller than the amount of the acid-modified hydrocarbon-based polymer contained in the dispersion liquid.
<8> The dispersion liquid according to any one of <1> to <7>, wherein the solvent is methyl ethyl ketone, cyclohexanone or N-methyl-2-pyrrolidone.
<9> The dispersion liquid according to any one of <1> to <8>, wherein the volume-based cumulative 50% diameter of the powder is 0.05 to 6 μm.
<10> The dispersion according to any one of <1> to <9>, wherein the tetrafluoroethylene-based polymer contains 99.5 mol% or more of units based on tetrafluoroethylene with respect to all units contained in the polymer. liquid.
<11> Any one of the above <1> to <9>, wherein the tetrafluoroethylene-based polymer contains more than 0.5 mol% of a unit based on a comonomer other than tetrafluoroethylene with respect to all units contained in the polymer. That dispersion.
<12> The tetrafluoroethylene-based 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, The dispersion liquid according to any one of 1> to <11>.
<13> The dispersion liquid according to any one of <1> to <12> is applied to the surface of a sheet base material to form a liquid film, and the liquid film is heated to give the powder and the acid-modified hydrocarbon. A method for producing a sheet material, comprising obtaining a sheet material having a layer containing a semi-cured product of a base polymer.
<14> The manufacturing method according to <13>, wherein the sheet material is an adhesive sheet using the layer as an adhesive layer between substrates.
<15> The manufacturing method according to <13>, wherein the sheet material is a coverlay film that adheres the layer to a printed wiring board so as to cover the metal wiring.

  According to the present invention, a layer (coating film) having adhesive properties (low temperature curability, adhesive strength, etc.), electrical properties (low dielectric constant, low dielectric loss tangent, etc.), and heat resistance (flame retardancy, etc.) is formed. Provided are a dispersion which can be obtained, and a method for producing a sheet material having a layer (coating film) exhibiting low temperature adhesiveness and excellent heat resistance (flame retardancy, etc.).

The following terms have the following meanings.
“D50 of powder” is a particle size distribution of powder measured by a laser diffraction / scattering method, and a cumulative curve is obtained by setting the total volume of particles (hereinafter, also referred to as “powder particles”) constituting the powder as 100%. , And the particle diameter at the point where the cumulative volume becomes 50% on the cumulative curve (volume-based cumulative 50% diameter).
"Powder D90" is a point where the particle size distribution of powder is measured by a laser diffraction / scattering method, the cumulative volume is calculated with the total volume of the powder particle group as 100%, and the cumulative volume becomes 90% on the cumulative curve. Is the particle size (volume-based cumulative 90% size).
That is, D50 and D90 of the powder are the volume-based cumulative 50% diameter and the volume-based cumulative 90% diameter of the powder particles, respectively.
The "melt viscosity of the polymer" is based on ASTM D 1238, and a sample of the polymer (2 g) which had been heated for 5 minutes at the measurement temperature in advance using a flow tester and a die of 2Φ-8L was loaded with 0.7 MPa. It is the value measured by holding at the measurement temperature at.
“Viscosity” is a value measured with a B-type viscometer at room temperature (25 ° C.) under the condition of a rotation speed of 30 rpm. The measurement is repeated three times, and the average value of the three measured values is used.
The "thermolysis initiation temperature of the dispersant" is a thermogravimetric analyzer (TG), thermogravimetric differential thermal analyzer (TG-DTA), and the dispersant (10 mg) is mixed with a mixed gas (helium 90% by volume and oxygen). 10% by volume) 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 may be an atomic group formed directly from a monomer by a polymerization reaction, and the polymer obtained by the polymerization reaction is treated by a predetermined method to convert an atomic group in which a part of the structure is converted. May be
"(Meth) acryloyloxy group" is a general term for an acryloyloxy group and a methacryloyloxy group.
“(Meth) acrylate” is a general term for acrylate and methacrylate.
"Weight average molecular weight (Mw)" is a standard polystyrene conversion value measured by gel permeation chromatography (hereinafter, also referred to as "GPC").

The dispersion of the present invention comprises a powder containing a tetrafluoroethylene-based polymer (hereinafter, also referred to as “F polymer”), a thermally decomposable fluoropolymer (hereinafter, also referred to as “D polymer”), and an acid-modified hydrocarbon-based polymer. (Hereinafter, also referred to as “HC polymer”) and a solvent, and the powder is dispersed in the solvent.
The sheet material according to the present invention is a layer containing a powder containing an F polymer and a semi-cured material of an HC polymer by applying the dispersion liquid to the surface of a sheet base material to form a liquid coating, and heating the liquid coating. That is, it is obtained by forming a semi-cured resin layer: hereinafter also referred to as "F layer". It can be said that this sheet material is obtained by forming a resin layer in which a powder containing an F polymer is dispersed in a semi-cured HC polymer.
Here, the semi-cured product means a cured product in a state where an exothermic peak due to the curing of the HC polymer appears when the F layer is subjected to the scanning scanning calorimetry measurement. That is, the semi-cured product means a state where the uncured HC polymer remains in the F layer (B stage state).

By using the dispersion of the present invention, it is possible to form an F layer having excellent electrical properties and heat resistance (flame retardancy, etc.) while exhibiting excellent adhesiveness at a relatively low temperature. Regarding the heat resistance of the F layer, the D polymer contained in the dispersion liquid functions as a dispersant to improve the powder dispersibility in the dispersion liquid and the interaction between the powder and the HC polymer, whereby the semi-cured HC polymer is obtained. It is considered that this is because the powder is easily dispersed uniformly in the powder.
Further, when the sheet material of the present invention is used as an adhesive sheet (bonding sheet) using the F layer as an adhesive layer between substrates or a coverlay film for adhering the F layer to a printed wiring board so as to cover metal wiring. During the bonding, the F layer is heated at a temperature of about 250 ° C. For this reason, if the D polymer that is a thermally decomposable dispersant is used, the amount of the D polymer contained in the F layer after complete curing (hereinafter, also referred to as “F layer after curing”) is likely to be significantly reduced. .. Therefore, the adverse effect of the D polymer on the HC polymer is unlikely to occur, and it is considered that the F layer after curing exhibits excellent adhesiveness due to the HC polymer.
The effects as described above are remarkably exhibited in a preferred embodiment of the present invention described later.

The D50 of the powder in the present invention is preferably 0.05 to 6 μm, more preferably 0.1 to 3 μm, still more preferably 0.2 to 3 μm. Within this range, the fluidity and dispersibility of the powder will be good, and the electrical characteristics (low dielectric constant, etc.) and heat resistance of the F layer after curing will be most easily exhibited. The D90 of the powder is preferably 8 μm or less, more preferably 6 μm or less, still more preferably 5 μm or less. Within this range, the fluidity and dispersibility of the powder will be good, and the electrical characteristics (low dielectric constant, etc.) and heat resistance of the F layer after curing will be most easily exhibited.
The loosely packed bulk density of the powder is preferably 0.05 g / mL or more, more preferably 0.08 to 0.5 g / mL. The dense packing bulk density of the powder is preferably 0.05 g / mL or more, more preferably 0.1 to 0.8 g / mL. When the loosely packed bulk density or the densely packed bulk density is within the above range, the powder is excellent in handleability.

The powder in the present invention may contain a resin other than the F polymer as long as the effect of the present invention is not impaired, but it is preferable to contain the F polymer as a main component. The content of the F polymer in the powder is preferably 80% by mass or more, more preferably 100% by mass.
Examples of the resin include aromatic polyester, polyamideimide, thermoplastic polyimide, polyphenylene ether, and polyphenylene oxide.

The F polymer in the present invention is a polymer containing a unit (hereinafter, also referred to as “TFE unit”) based on tetrafluoroethylene (hereinafter, also referred to as “TFE”).
The F polymer is a homopolymer composed of TFE units (hereinafter also referred to as "PTFE"), a unit based on TFE units and perfluoro (alkyl vinyl ether) (hereinafter also referred to as "PAVE") (hereinafter also referred to as "PAVE unit"). A copolymer containing TFE units and hexafluoropropylene (hereinafter also referred to as “HFP”) units (hereinafter also referred to as “HFP units”) or a TFE unit and fluoroalkyl ethylene ( Hereinafter, a copolymer including a unit based on “FAE” (hereinafter, also referred to as “FAE unit”) is preferable.

The homopolymer composed of TFE units also includes a polymer containing a very small amount of units other than TFE units. The polymer containing an extremely small amount of other units preferably contains 99.5 mol% or more, and more preferably 99.9 mol% or more of TFE units based on all the 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, more preferably 1 × 10 ³ to 1 × 10 ⁶ Pa · s.
Such polymers include low molecular weight PTFE.

Low molecular weight PTFE is obtained by irradiating high molecular weight PTFE (melt viscosity of about 1 × 10 ⁹ to 1 × 10 ¹⁰ Pa · s) with radiation (International Publication No. 2018/026012, International Publication No. 2018). No. / 026017, etc.), and a PTFE obtained by using a chain transfer agent in the production of PTFE by polymerizing TFE (JP 2009-1745 A, WO 2010/114033). And a polymer described in JP-A-2005-232082), which has a core-shell structure composed of a core portion and a shell portion, and in which only the shell portion has the above-mentioned melt viscosity PTFE ( Polymers described in Japanese Patent Publication No. 2005-527652, International Publication No. 2016/170918, Japanese Patent Laid-Open No. 09-087334, etc.).
The standard specific gravity of low molecular weight PTFE (specific gravity measured according to ASTM D4895-04) is preferably 2.14 to 2.22, more preferably 2.16 to 2.20.

F polymers also include polymers containing other units than TFE units. The polymer containing other units preferably contains more than 0.5 mol% of other units with respect to the total units of the polymer. Such other units are preferably PAVE units, HFP units, FAE units or units having a functional group described later.
The F polymer 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 F polymer has the above functional group, the adhesiveness of the F layer is further improved. The carbonyl group-containing group includes an amide group.

The functional group may be contained in a unit constituting the F polymer, may be contained in an end group of the polymer main chain, or may be introduced into the F polymer by plasma treatment or the like. Examples of the F polymer having the above functional group in the terminal group of the polymer main chain include F polymers having a functional group as the terminal group derived from a polymerization initiator, a chain transfer agent and the like.
The functional group is preferably a hydroxy group or a carbonyl group-containing group, more preferably a carbonyl group, more preferably a carbonate group, a carboxy group, a haloformyl group, an alkoxycarbonyl group or an acid anhydride residue, and a carboxy group or an acid anhydride. Residues are more preferred.
The F polymer is preferably a polymer containing a TFE unit, a PAVE unit, an 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 hydroxy group or a carbonyl group-containing group is preferable, a monomer having an acid anhydride residue or a monomer having a carboxy group is more preferable, and a cyclic monomer having an acid anhydride residue is particularly preferable. preferable.
Examples of the cyclic monomer include itaconic anhydride, citraconic anhydride, 5-norbornene-2,3-dicarboxylic acid anhydride (also known as hymic acid anhydride; hereinafter also referred to as “NAH”) or maleic anhydride. Is preferred.

The _{PAVE, CF 2 = CFOCF 3,} CF 2 = CFOCF 2 CF 3, CF 2 = CFOCF 2 CF 2 CF 3 ( hereinafter, also referred to as _{"PPVE".), CF 2 = CFOCF 2} CF 2 CF 2 CF 3, _{CF 2 = CFO (CF 2)} 8 F can be mentioned, PPVE is preferred.
As FAE, CH ₂ ═CH (CF ₂ ) ₂ F, CH ₂ ═CH (CF ₂ ) ₃ F, CH ₂ ═CH (CF ₂ ) ₄ F, CH ₂ ═CF (CF ₂ ) ₃ H, CH ₂ ═CF (CF ₂ ) ₄ H, and CH ₂ ═CH (CF ₂ ) ₄ F or CH ₂ ═CH (CF ₂ ) ₂ F is preferable.
In this case, the TFE unit is preferably contained in an amount of 90 to 99 mol% and the PAVE unit, the HFP unit or the FAE unit is contained in an amount of 0.5 to 9.97 mol% based on all the units contained in the F polymer. Preferably, the unit having a functional group is contained in an amount of 0.01 to 3 mol%.
In this case, the melting point of the F polymer is preferably 250 to 380 ° C, more preferably 280 to 350 ° C.
Specific examples of such F polymers include the polymers described in WO2018 / 16644.

The solvent in the present invention is a compound which is liquid at 25 ° C, and may be an aqueous solvent or a non-aqueous solvent.
The solvent is preferably water, amide, alcohol, sulfoxide, ester, ketone or glycol ether, more preferably water, ketone or amide, still more preferably ketone or amide. The fluorine-based dispersant in the present invention has a high interaction with these solvents, and thus the coating film-forming properties (thixo ratio, adhesiveness, transparency, etc.) of the dispersion are easily improved. As the solvent, one type may be used alone, or two or more types may be used in combination.

Specific examples of the solvent include water, methanol, ethanol, isopropanol, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, diethyl ether, dioxane, ethyl lactate, ethyl acetate. , Butyl acetate, methyl ethyl ketone, methyl isopropyl ketone, cyclopentanone, cyclohexanone, ethylene glycol monoisopropyl ether, cellosolve (methyl cellosolve, ethyl cellosolve, etc.).
The solvent is preferably a compound that does not instantly volatilize, and specifically, a compound having a boiling point of 80 to 275 ° C. is more preferable, and a compound having a boiling point of 125 to 250 ° C. is further preferable. Within this range, when the solvent is distilled off from the dispersion by heating, the volatilization of the solvent and the decomposition and flow of the D polymer effectively proceed.

  The compound of such a solvent is preferably methyl ethyl ketone, cyclohexane, 2-propanol, 1-propanol, 1-butanol, 1-methoxy-2-propanol, (N-methyl-2-pyrrolidone, γ-butyrolactone, cyclohexanone or cyclopentanone. , Methyl ethyl ketone, cyclohexanone or N-methyl-2-pyrrolidone are more preferred.

The thermally decomposable fluoropolymer (D polymer) in the present invention is preferably a fluoropolymer having a thermal decomposition initiation temperature of 250 ° C or lower. The D polymer is a polymer other than the F polymer and the HC polymer.
100-250 degreeC is preferable and, as for the thermal decomposition start temperature of D polymer, 125-200 degreeC is more preferable. Since the D polymer having such a thermal decomposition starting temperature is difficult to decompose at room temperature, it suitably functions as a powder dispersant in the dispersion liquid. Further, since it is hard to remain in the F layer after curing, the electrical characteristics (low dielectric constant, etc.) and heat resistance of the F layer after curing are further improved.
The weight average molecular weight of the D polymer is preferably 2,000 to 80,000, more preferably 6,000 to 20,000. The D-polymer having such a weight-average molecular weight has an excellent function as a dispersant and is less likely to remain in the F layer after curing when decomposed.

  The D polymer is preferably a polymer having a main chain and a side chain branched from the main chain having a leaving group. The D-polymer having a leaving group has a high thermal decomposability because the leaving group is easily released from the main chain when heated and a radical is easily generated. Further, if the type of the leaving group is selected, the affinity of the D polymer for the powder and the solvent can be adjusted accordingly.

The D polymer preferably has any of the groups represented by the following formulas (1) to (4) in the side chain.
(1) -C (O) OCH (CH 3) OR 1
(2) -C (O) OC (-R 2) 3
_{(3) -C (O) OCH} 2 -R 3
^{(4) -C (O) OC} (-R 41) (- R 42) 2
The symbols in the formulas have the following meanings.
R ¹ is a polyfluoroalkyl group or a polyfluoroalkyl group containing an etheric oxygen atom, and is a polyfluoroalkyl group having 1 to 6 carbon atoms or a polyfluoroalkyl group having a carbon number of 3 to 6 containing an etheric oxygen atom. preferable.
R ² is an alkyl group or an aryl group, and the three R ² may be the same or different. R ² is preferably an alkyl group having 1 to 6 carbon atoms, and more preferably a methyl group. It is preferred that the three R ² are the same.
R ³ is an aryl group, preferably a phenyl group.
R ⁴¹ is a hydrogen atom or an alkoxy group, preferably a hydrogen atom or an alkoxy group having 1 to 3 carbon atoms, and more preferably a hydrogen atom.
R ⁴² is an alkyl group, and two R ^{42 s} may be the same or different, and may jointly form an alkylene group. The alkylene group formed together may be linear or branched, and may form a ring structure in the group. Moreover, an unsaturated bond or a hetero atom may be contained in the alkylene group.
It is preferable that the two R ^{42 s} together form an alkylene group.

Specific examples of the group represented by the formula _{(1), -C (O)} OCH (CH 3) O (CF 2) 4 F, -C (O) OCH (CH 3) O (CF 2) 6 F _{, -C (O) OCH (CH} 3) OCH 2 CF (CF 3) OCF 2 CF 2 CF 3, -C (O) OCH (CH 3) OCH 2 CF (CF 3) OCF 2 CF (CF 3) OCF _{2 CF 2 CF 3, -C (} O) OCH (CH 3) OCH (CF 3) 2, -C (O) OCH (CH 3) OCH 2 CF 2 CF 3, -C (O) OCH (CH 3) _{OCH 2 CF 3, -C (O} ) OCH (CH 3) O (CH 2) 6 CF 2 CF 3, -C (O) OCH (CH 3) O (CH 2) 2 CF 2 CF 2 CF 2 CF 2 _{CF 2 CF 3, -C (O} ) OCH (CH 3) O (CH 2) 2 CF 2 CF 2 CF 2 CF 3, -C (O) OCH (CH 3) O (CH 2) CF 2 CF 2 CF _{3, -C (O) OCH (} CH 3) O (CH 2) CF 2 CF 2 CF 2 CF 3, -C (O) OCH (CH 3) O (CH 2) CF 2 CF 2 CF 2 CF 2 CF _{2 CF 3, -C (O)} OCH (CH 3) OCF 2 OCF 2 CF 2 OCF 2 CF 3, -C (O) OCH (CH 3) OCF (CF 3) OCF 2 CF 2 CF 3, -C ( _{O) OCH (CH 3) OCF} (CF 3) C (= C (CF 3) 2) (CF (CF 3) 2), - C (O) OCH (CH 3) OC (CF 3) C (= C _{(CF (CF 3) 2)} 2) can be mentioned. Among them, the group represented by the formula (1) is —C (O) OCH (CH ₃ ) O (CF ₂ ) ₄ F or —C (O) from the viewpoint of further excellent physical properties (adhesiveness, etc.) of the F layer. _{) OCH (CH 3) O (} CF 2) 6 F are _{preferred, -C (O) OCH (CH} 3) O (CF 2) 6 F is more preferred.

Specific examples of the groups represented by formulas (2) to (4) include the following groups. In the formula, * is a bond.

The D polymer is a unit based on a compound represented by the following formula F (hereinafter, also referred to as “unit F”) and a unit based on a compound represented by any of the following formulas D1 to D4 (hereinafter referred to as “unit D”). Also referred to as ".") Is preferable.
Formula F: CH ₂ = CX ^F C (O) O-Q ^F- R ^F
Formula ^{_{D1: CH 2 = CX 1 C}} (O) OCH (CH 3) OR 1
Wherein ^{_{D2: CH 2 = CX 2 C}} (O) OC (-R 2) 3
Formula ^{_{D3: CH 2 = CX 3 C}} (O) OCH 2 -R 3
Wherein ^{_{D4: CH 2 = CX 4 C}} (O) OC (-R 41) (- R 42) 2
The symbols in the formulas have the following meanings.
X ^F is a hydrogen atom, a chlorine atom or a methyl group, preferably a hydrogen atom or a methyl group.
Q ^F is a methylene group _(-CH 2 -), ethylene group _(-CH 2 _CH 2 -), an oxyethylene group _(-CH 2 _CH 2 O-) or oxybutylene group _{(-CH 2 CH 2 CH 2 CH} 2 O-). When R ^F is a C 1-6 polyfluoroalkyl group or a C 3-6 polyfluoroalkyl group containing an etheric oxygen atom, Q ^F is preferably a methylene group or an ethylene group. Further, when R ^F is a polyfluoroalkenyl group having 4 to 12 carbon atoms, Q ^F is preferably an oxyethylene group or an oxybutylene group.
R ^F is a polyfluoroalkyl group having 1 to 6 carbon atoms, a polyfluoroalkyl group having 3 to 6 carbon atoms containing an etheric oxygen atom, or a polyfluoroalkenyl group having 4 to 12 carbon atoms. The ^{_{R F, - (CF 2)}} 4 F, - (CF 2) 6 F, -CF 2 OCF 2 CF 2 OCF 2 CF 3, -CF (CF 3) OCF 2 CF 2 CF 3, -CF (CF _{3) C (= C (CF} 3) 2) (CF (CF 3) 2) or _{-C (CF 3) C (=} C (CF (CF 3) 2) 2) is preferable, - _{(CF 2) 4 F, - (CF 2) 6} F, -CF 2 OCF 2 CF 2 OCF 2 CF 3 or _-CF (CF ₃₎ is more preferably OCF 2 _CF 2 _{CF 3.} Among them, from the viewpoint of the physical properties of the sheet material (adhesion, etc.) are more excellent, ^{R F} is, - _{(CF 2) 4} F or - _{(CF 2) 6} F are more preferred, - _{(CF 2) 6} F is particularly preferred . In particular, the compound represented by the above formula F having a linear polyfluoroalkyl group is suitable because it is available at a relatively low cost.
X ¹ , X ² , X ³ and X ⁴ are each independently a hydrogen atom or a methyl group.
R ¹ , R ² , R ³ , R ⁴¹ and R ⁴² have the same meanings as described above, and the respective preferable ranges are also the same.

20-60 mol% is preferable and, as for the quantity of the unit F with respect to all the units contained in the said polymer, 20-40 mol% is more preferable.
The amount of the unit D with respect to all units contained in the polymer is preferably 40 to 80 mol%, more preferably 60 to 80 mol%.
When the amount of each unit with respect to all units contained in the polymer is in the above range, the dispersibility of the dispersion liquid is further improved, and various physical properties of the F layer are well-balanced. Further, the thermal decomposition start temperature of the D polymer is further lowered.
The D polymer may be composed of only the units F and D, and may further contain additional units other than the units F and D as long as the effects of the present invention are not impaired.

  10-60 mass% is preferable, as for the fluorine content of D polymer in this invention, 20-50 mass% is more preferable, and its 25-45 mass% is still more preferable. Since the lower limit of the fluorine content is within the above range, the dispersibility of the dispersion is excellent. Since the upper limit of the fluorine content is within the above range, the affinity of the D polymer for each component of the dispersant is balanced, and in addition to the dispersibility of the dispersion, the layer (coating film) formability thereof is easily improved. For example, the F layer is characterized by high wettability and excellent smoothness and adhesiveness. The fluorine content of the D polymer can be calculated from the type of monomer used in its synthesis and the amount charged.

The acid-modified hydrocarbon-based polymer (HC polymer) contained in the dispersant of the present invention is a polymer obtained by acid-modifying a hydrocarbon-based polymer, and a polymer having an acid value (acid) obtained by acid-modifying a polyolefin. It is preferably a modified polyolefin). The HC polymer is a polymer other than the F polymer and the D polymer.
The polyolefin is preferably a polymer containing units based on at least one olefin selected from the group consisting of ethylene, propylene, butene, pentene, hexene, octene and 4-methyl-pentene, more preferably a polymer containing at least propylene-based units. preferable.
Polyolefins include polymers consisting of propylene-based units and ethylene-based units, polymers consisting of propylene-based units and butene-based units, propylene-based units, ethylene-based units and butene-based units. .. The amount of units based on propylene with respect to all units in these polymers is preferably 50 mol% or more.

As the modifier used for the acid modification of the HC polymer, α, β-unsaturated carboxylic acids are preferable, and maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, aconitic acid or norbornene dicarboxylic acid is preferable. .. The use of these modifiers makes it easy to graft the HC polymer and adjust it to the graft polymer. When the HC polymer is a graft polymer, not only the adhesion is excellent, but also the powder is easily dispersed uniformly in the F layer.
The acid value of the HC polymer is preferably 0.5 to 40 mgKOH / g, more preferably 1.0 to 30 mgKOH / g.
The weight average molecular weight of the HC polymer is preferably 50,000 to 200,000.

The dispersion of the present invention preferably further contains a polymer capable of reacting with an HC polymer, such as a phenol resin, a modified polyphenylene ether resin, a polyfunctional cyanate ester resin, a polyfunctional maleimide-cyanate ester resin, a polyfunctional maleimide resin. Alternatively, it preferably contains an epoxy resin, more preferably an epoxy resin.
Specific examples of the epoxy resin include bisphenol A type epoxy resin or hydrogenated product thereof; bisphenol F type epoxy resin or hydrogenated product thereof; orthophthalic acid diglycidyl ester, isophthalic acid diglycidyl ester, terephthalic acid diglycidyl ester, p- Glycidyl ester-based epoxy resins such as hydroxybenzoic acid glycidyl ester, tetrahydrophthalic acid diglycidyl ester, succinic acid diglycidyl ester, adipic acid diglycidyl ester, sebacic acid diglycidyl ester, trimellitic acid triglycidyl ester; ethylene glycol diglycidyl ether , Propylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, tetraphenylglycidyl ether ethane, triphenylglycidyl ether Glycidyl ether epoxy resins such as ethane, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether; glycidyl amine epoxy resins such as triglycidyl isocyanurate, tetraglycidyl diaminodiphenylmethane; epoxidized polybutadiene, epoxidized soybean oil, etc. Aliphatic epoxy resin; novolac type epoxy resin such as phenol novolac epoxy resin, o-cresol novolac epoxy resin, bisphenol A novolac epoxy resin; brominated bisphenol A type epoxy resin, phosphorus-containing epoxy resin, dicyclopentadiene skeleton-containing epoxy resin , Naphthalene skeleton-containing epoxy resin, anthracene type epoxy resin, tertiary butyl catechol type epoxy resin, triphenylmethane type epoxy resin, tetraphenylethane type epoxy resin, biphenyl type epoxy resin, bisphenol S type epoxy resin.
The dispersion liquid of the present invention may further contain a crosslinking agent, a curing agent, a curing aid, and the like.

The amount of powder contained in the dispersion of the present invention is preferably smaller than the amount of HC polymer contained in the dispersion.
The proportion of the HC polymer in the dispersant is preferably 20 to 60% by mass, more preferably 25 to 50% by mass. Within this range, it is easy to form an F layer having excellent adhesiveness.
The proportion of the powder in the dispersion liquid of the present invention is preferably 1 to 20% by mass, more preferably 3 to 15% by mass. Within this range, it is easy to form an F layer having excellent electrical characteristics and heat resistance.
The proportion of the thermally decomposable fluoropolymer in the dispersion of the present invention is preferably 1 to 10% by mass. Within this range, the dispersibility of the dispersion liquid is further improved, and the physical properties (wetting property, adhesiveness, etc.) of the F layer are more easily improved.
10-60 mass% is preferable, and, as for the ratio of the solvent in the dispersion liquid of this invention, 10-50 mass% is more preferable. Within this range, the coatability of the dispersion is excellent and the layer (coating film) formability is easily improved.

The dispersion liquid of the present invention may contain other materials as long as the effects of the present invention are not impaired. Other materials may or may not dissolve in the dispersion.
Such other materials include non-curable resins.
Examples of non-curable resins include non-meltable resins and heat-meltable resins.
Examples of the non-meltable resin include a cured product of a curable resin.
Examples of the heat-meltable resin include thermoplastic resins such as thermoplastic polyimide and heat-curable cured products of curable resins.

As the thermoplastic resin, polyester resin, polyolefin resin, styrene resin, polycarbonate, thermoplastic polyimide, polyarylate, polysulfone, polyallylsulfone, aromatic polyamide, aromatic polyetheramide, polyphenylene sulfide, polyallyl ether ketone, polyamide Examples thereof include imide, liquid crystalline polyester and polyphenylene ether, and thermoplastic polyimide, liquid crystalline polyester or polyphenylene ether are preferable.
Examples of such other materials include thixotropic agents, antifoaming agents, inorganic fillers, reactive alkoxysilanes, dehydrating agents, plasticizers, weathering agents, antioxidants, heat stabilizers, lubricants, antistatic agents, and additives. A whitening agent, a coloring agent, a conductive agent, a release agent, a surface treatment agent, a viscosity modifier, and a flame retardant are also included.

The viscosity of the dispersion liquid of the present invention is preferably 50 to 10,000 mPa · s, more preferably 75 to 1,000 mPa · s, and further preferably 100 to 500 mPa · s. In this case, not only is the dispersibility of the dispersion liquid excellent, but also its coatability and the miscibility with the varnish of different polymers are excellent.
The thixo ratio (η ₁ / η ₂ ) of the dispersion liquid of the present invention is preferably 1.0 to 2.2, more preferably 1.4 to 2.2, and even more preferably 1.5 to 2.0. In this case, not only the dispersibility of the dispersion is excellent, but also the coatability of the dispersion is good, and the homogeneity of the F layer is easily improved. In addition, such a dispersion has a higher mixability with a varnish of different polymers. The thixo ratio (η ₁ / η ₂ ) is obtained by dividing the viscosity η _{1 of the} dispersion liquid measured at a rotation speed of 30 rpm by the viscosity η ₂ of the dispersion liquid measured at a rotation speed of 60 rpm. Calculated.

The dispersion of the present invention can be used as a coating agent or the like which can form an F layer on the surface of a substrate when applied to the surface of various substrates. For example, by using the dispersion liquid of the present invention, it is possible to easily produce an adhesive sheet including an F layer having excellent adhesiveness, a sheet material used for a cover lay film and the like.
That is, in the method for producing a sheet material of the present invention, the above-mentioned dispersion is applied to the surface of a sheet base material to form a liquid coating, and the liquid coating is heated to remove the solvent from the liquid coating and to remove the HC polymer half. It can also be said to be a method of curing and forming a resin layer (F layer) in which powder is dispersed in a semi-cured HC polymer.

It is considered that the powder particles to which the HC polymer adheres are stably dispersed in the dispersion liquid and the liquid coating film by the action of the D polymer (fluorine-based dispersant). Therefore, in the dry coating film in which the solvent is removed from the liquid coating film, adjacent powder particles do not come into direct contact with each other due to the presence of the HC polymer, and between the powder particles, depending on the size of the HC polymer. The distance is secured. When the HC polymer is semi-cured by heating in this state, the F layer in which the powder particles are uniformly dispersed in the semi-cured HC polymer is formed.
Further, since the D polymer has a low thermal decomposition starting temperature, a part thereof is decomposed even during the above heating and hardly remains in the F layer. Therefore, the F layer exhibits uniform physical properties (adhesion, etc.) based on the properties of the semi-cured HC polymer.

When the sheet material in the present invention is an adhesive sheet in which the F layer is used as an adhesive layer between substrates, the sheet base material can be composed of a release sheet.
When the sheet material is a cover lay film in which the F layer is joined to the printed wiring board so as to cover the metal wiring, the sheet base material can be made of a heat resistant resin film.
The heat resistant resin film is a film containing at least one kind of heat resistant resin, and may be a single layer film or a multilayer film.
Examples of the heat resistant resin include polyimide, polyarylate, polysulfone, polyallyl sulfone, aromatic polyamide, aromatic polyether amide, polyphenylene sulfide, polyallyl ether ketone, polyamide imide, and liquid crystalline polyester.

In the present invention, the dispersion liquid is applied to the surface of the sheet base material. The application method may be any method as long as it forms a stable liquid film (wet film) made of a dispersion liquid on the surface of the sheet base material, and examples thereof include a coating method, a droplet discharge method, and a dipping method. preferable. If the coating method is used, a liquid coating can be efficiently formed on the surface of the substrate with simple equipment.
As a coating method, a spray method, a roll coating method, a spin coating method, a gravure coating method, a micro gravure coating method, a gravure offset method, a knife coating method, a kiss coating method, a bar coating method, a die coating method, a fountain Mayer bar method, a slot die coating method. There is a law.

During heating, the liquid coating is held at the volatilization temperature of the solvent to dry the liquid coating, and then the dried coating is held at a temperature above the volatilization temperature of the solvent (particularly, the curing temperature of the HC polymer). Semi-cure the polymer. In this way, the F layer in which the powder is uniformly dispersed in the semi-cured HC polymer (matrix resin) is formed on the surface of the sheet base material.
The “solvent volatilization temperature” is preferably the boiling point of the solvent ± 50 ° C., more preferably the temperature above the boiling point of the solvent, and even more preferably the temperature above the boiling point of the solvent + 50 ° C.
The temperature during drying usually means the temperature of the dry atmosphere.
At the time of drying, the solvent does not necessarily have to be completely volatilized, and may be volatilized to such an extent that the layer shape after holding is stable and the self-supporting film can be maintained. Specifically, the amount of the solvent to be volatilized is preferably 50% by mass or more of the solvent contained in the dispersion liquid.

The drying may be carried out in one step at a constant temperature, or in two or more steps at different temperatures.
Examples of the drying method include a method using an oven, a method using a ventilation drying furnace, and a method of irradiating heat rays such as infrared rays.
Drying may be performed under either normal pressure or reduced pressure.
Further, the dry atmosphere may be any of an oxidizing gas atmosphere (oxygen gas etc.), a reducing gas atmosphere (hydrogen gas etc.) and an inert gas atmosphere (helium gas, neon gas, argon gas, nitrogen gas etc.). ..
The drying temperature is preferably 50 to 280 ° C, more preferably 120 to 260 ° C. The drying time is preferably 0.1 to 30 minutes, more preferably 0.5 to 20 minutes.
If the liquid coating is dried under the conditions as described above, the F layer can be suitably solid-formed while maintaining high productivity.

Examples of the curing method include a method using an oven, a method using a ventilation drying furnace, and a method of irradiating heat rays such as infrared rays.
As a curing method, a method of irradiating far infrared rays is preferable because the HC polymer can be semi-cured in a short time and has a relatively compact size. The curing method may be a method combining infrared heating and hot air heating.
The effective wavelength band of far infrared rays is preferably 2 to 20 μm, and more preferably 3 to 7 μm in order to promote uniform curing (polymerization) of the HC polymer.
In addition, in order to improve the smoothness of the surface of the formed F layer, you may press a dry film with a heating plate, a heating roll, etc.

Curing may be performed under either normal pressure or reduced pressure. Further, the curing atmosphere may be any of an oxidizing gas atmosphere, a reducing gas atmosphere and an inert gas atmosphere. However, from the viewpoint of suppressing oxidative deterioration of the sheet base material and the formed F layer, the reducing atmosphere A gas atmosphere and an inert gas atmosphere are preferable.
The curing temperature is set according to the type of HC polymer, and is preferably 180 ° C to 400 ° C, more preferably 200 to 380 ° C, even more preferably 220 ° C to 370 ° C.
The temperature at which the HC polymer is semi-cured usually means the temperature of the curing atmosphere.
The curing time is preferably 30 seconds to 30 minutes, more preferably 1 to 15 minutes.
If the dry coating is heated under these conditions, the curing of the HC polymer is promoted, the productivity of the sheet material is increased, and the generation of hydrofluoric acid due to the decomposition of the F polymer is easily suppressed.

At this stage, the amount of the dispersant remaining in the F layer (semi-cured resin layer) is preferably 30% or less of the amount of the dispersant contained in the dispersion, and more preferably 10 to 20%. With the F layer in which the dispersant remains in this amount, high adhesiveness to the substrate and the like can be maintained, and the sheet material can be easily handled.
On the other hand, the amount of the dispersant remaining in the F layer after curing is preferably 10% or less of the amount of the dispersant contained in the dispersion, and more preferably 5% or less. When the amount of the dispersant remaining in the F layer after curing is sufficiently small, the F layer after curing has a good balance of high adhesiveness due to the HC polymer and excellent properties (heat resistance, electric properties) due to the F polymer. Can be demonstrated.

The method for manufacturing the dispersion liquid and the sheet material of the present invention has been described above, but the present invention is not limited to the configurations of the above-described embodiments.
For example, the dispersion of the present invention may have any other configuration added to the configuration of the above-described embodiment or may be replaced with any configuration exhibiting the same function.
Further, the sheet material manufacturing method of the present invention may have other optional steps in addition to the configurations of the above-described embodiments, and may be replaced with arbitrary steps that produce a similar action.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.
1. Preparation of each component [F polymer]
F polymer: a copolymer containing TFE-based units, NAH-based units and PPVE-based units in this order: 97.9 mol%, 0.1 mol%, 2.0 mol% [powder]
Powder: Powder made of F polymer having D50 of 1.7 μm and D90 of 3.8 μm. D50 and D90 are laser diffraction / scattering type particle size distribution measuring devices (LA-920 measuring device manufactured by Horiba Ltd.). The powder was dispersed in water and measured.

[D polymer]
D Polymer 1: Copolymer of Monomer F ¹ , Monomer H ¹ , Monomer H ² and Monomer R ¹ (Nonionic property, Thermal decomposition start temperature: 200 ° C. or less)
D polymer 2: Copolymer of monomer F ² and monomer AO ¹ (nonionic, thermal decomposition starting temperature: over 250 ° C.)

[monomer]
Monomer ^{_{F 1: CH 2 = C (}} CH 3) C (O) OCH 2 CH 2 (CF 2) 6 F
Monomer ^{_{F 2: CH 2 = CHCOO (}} CH 2) 4 OCF (CF 3) (C (CF (CF 3) 2) (= C (CF 3) 2)
Monomer ^{_{H 1: CH 2 = C (}} CH 3) C (O) OCH 2 -Ph
Monomer ^{_{H 2: CH 2 = C (}} CH 3) C (O) OCH <Nb
Monomer _{^{R 1: CH 2 = CHC (}} O) O (CH 2) 18 H
Monomer AO ¹ : CH ₂ = CHC (O) OCH ₂ CH ₂ (OCH ₂ CH ₂ ) ₁₀ OH
In the formula, “Ph” is a phenyl group and “CH <Nb” is an isobornyl group.

2. Preparation of dispersion (Example 1)
First, 40 parts by mass of N-methyl-2-pyrrolidone was mixed with 5 parts by mass of D polymer 1 and 40 parts by mass of powder to prepare a mixed solution.
Next, 20 parts by mass of the mixed liquid and 80 parts by mass of the varnish solution were mixed to obtain a dispersion liquid 1 (thermosetting composition). The varnish solution contains 50% by mass and 25% by mass of an acid-modified polyolefin (a graft polymer obtained by acid-modifying a copolymer of propylene and butene with maleic anhydride) as an HC polymer and an epoxy resin in this order. Including solvent and curing agent.
(Example 2)
Dispersion liquid 2 was obtained in the same manner as in Example 1 except that D polymer 1 was changed to D polymer 2.
(Example 3)
The varnish solution in Example 1 was used as is.

3. Preparation of Coverlay Film (Sheet Material) First, the obtained dispersion liquid was applied to the surface of a polyimide sheet base material to form a liquid film.
Next, this liquid film was heated at 120 ° C. for 3 minutes in the air atmosphere to obtain a dry film.
After that, the dry coating was heated at 180 ° C. for 15 minutes in the air atmosphere to semi-cure the HC polymer to produce a coverlay film having an F layer. In the F layer, the semi-cured product of the HC polymer formed the matrix resin, and the F powder was dispersed in the matrix resin.

4. Evaluation 4-1. Transmission Loss First, the surface of the copper foil of the single-sided copper-clad laminate was gold flash plated.
Next, the copper foil was processed to form a coplanar-type metal wiring to obtain a printed wiring board. The characteristic impedance of the metal wiring was 50Ω and the total length was 50 mm.
Then, the coverlay film was laminated on the printed wiring board so that the F layer was in contact with the metal wiring to obtain a laminate.
Then, this laminated body was vacuum hot pressed to completely cure the F layer. The processing conditions were temperature: 185 ° C., pressurizing pressure: 3.0 MPa, pressurizing time: 60 minutes.

A 28 GHz signal processed by a vector network analyzer was supplied to the metal wiring of the obtained laminated body through a high frequency contact probe of GSG (250 μm pitch), and the transmission loss per unit length was measured. TRL calibration (Thru-Reflect-Line calibration) was used for the calibration.
In addition, as a measure of the transmission loss, "S-parameter" (hereinafter, also referred to as "S value"), which is one of the circuit network parameters used for expressing the characteristics of the high frequency electronic circuit or the high frequency electronic component. used. The closer the S value is to 0, the smaller the transmission loss.
The transmission loss was evaluated according to the following criteria based on the calculated S value.
[Evaluation criteria]
◯: S value exceeds -1.6 ×: S value is less than -1.6

4-2. Adhesiveness The peel strength of the laminate obtained above was measured, and the adhesiveness was evaluated according to the following criteria.
[Evaluation criteria]
Good: Peel strength is 10 N / cm or more.
Δ: Peel strength is 5 N / cm or more and less than 10 N / cm.
X: Peel strength is less than 5 N / cm.
4-3. Flame Retardancy The laminate obtained above was evaluated for flame retardancy in accordance with UL94 standard.
[Evaluation criteria]
◯: It has flame retardancy equivalent to V-0 class.
X: There is no flame retardancy equivalent to V-0 class.
The above results are shown in Table 1 below.

  In Example 1 using a thermally decomposable fluoropolymer having a thermal decomposition starting temperature of 250 ° C. or less (particularly 200 ° C. or less) as a dispersant, a coverlay film having excellent F layer adhesiveness was obtained, and its electrical characteristics were excellent. Was there. On the other hand, in Example 2 in which the polymer having a temperature higher than 250 ° C. was used as the dispersant, the adhesion of the F layer was inferior to that in Example 1.

  The dispersion of the present invention is excellent in dispersibility and layer (coating film) formability, and can be easily processed into a film, a fiber reinforced film, a prepreg, a metal laminate (metal foil with resin), and a processed article obtained. Can be used as a material for antenna parts, printed circuit boards, aircraft parts, automobile parts, sports equipment, food industry products, saws, sliding bearings and the like.

Claims (15)

  A dispersion liquid containing a powder containing a tetrafluoroethylene-based polymer, a thermally decomposable fluoropolymer, an acid-modified hydrocarbon-based polymer, and a solvent, and the powder being dispersed in the solvent.   The dispersion according to claim 1, further comprising an epoxy resin.   The dispersion according to claim 1 or 2, wherein the thermal decomposition starting temperature of the thermally decomposable fluoropolymer is 250 ° C or lower. The dispersion according to any one of claims 1 to 3, wherein the thermally decomposable fluoropolymer has any of groups represented by the following formulas (1) to (4) in a side chain.
(1) -C (O) OCH (CH 3) OR 1
(2) -C (O) OC (-R 2) 3
_{(3) -C (O) OCH} 2 -R 3
^{(4) -C (O) OC} (-R 41) (- R 42) 2
[In the formula, R ¹ represents a polyfluoroalkyl group or a polyfluoroalkyl group containing an etheric oxygen atom, R ² represents an alkyl group or an aryl group (three R ² may be the same. R ³ represents an aryl group, R ⁴¹ represents a hydrogen atom or an alkoxy group, and R ⁴² represents an alkyl group (two R ⁴² may be the same). They may be different and may together form an alkylene group.). ] The thermally decomposable fluoropolymer is a polymer comprising a unit based on a compound represented by the following formula F and a unit based on a compound represented by any of the following formulas D1 to D4. The dispersion according to any one of items.
Formula F: CH ₂ = CX ^F C (O) O-Q ^F- R ^F
Formula ^{_{D1: CH 2 = CX 1 C}} (O) OCH (CH 3) OR 1
Wherein ^{_{D2: CH 2 = CX 2 C}} (O) OC (-R 2) 3
Formula ^{_{D3: CH 2 = CX 3 C}} (O) OCH 2 -R 3
Wherein ^{_{D4: CH 2 = CX 4 C}} (O) OC (-R 41) (- R 42) 2
[In the formula, X ^F represents a hydrogen atom, a chlorine atom or a methyl group, Q ^F represents a methylene group, an ethylene group, an oxyethylene group or an oxybutylene group, and X ¹ , X ² , X ³ and X ⁴ Each independently represent a hydrogen atom or a methyl group, and R ^F represents a polyfluoroalkyl group having 1 to 6 carbon atoms, a polyfluoroalkyl group having 3 to 6 carbon atoms containing an etheric oxygen atom, or 4 to 4 carbon atoms. 12 represents a polyfluoroalkenyl group, R ¹ represents a polyfluoroalkyl group or a polyfluoroalkyl group containing an etheric oxygen atom, R ² represents an alkyl group or an aryl group (three R ² are the same). R ³ represents an aryl group, R ⁴¹ represents a hydrogen atom or an alkoxy group, R ⁴² represents an alkyl group (two R ⁴² are the same). Or may be different from each other, and may together form an alkylene group.). ]   The dispersion according to any one of claims 1 to 5, wherein the acid-modified hydrocarbon-based polymer is an acid-modified polyolefin.   The dispersion according to any one of claims 1 to 6, wherein the amount of the powder contained in the dispersion is smaller than the amount of the acid-modified hydrocarbon-based polymer contained in the dispersion.   The dispersion according to claim 1, wherein the solvent is methyl ethyl ketone, cyclohexanone or N-methyl-2-pyrrolidone.   The dispersion according to any one of claims 1 to 8, wherein a volume-based cumulative 50% diameter of the powder is 0.05 to 6 µm.   The dispersion according to any one of claims 1 to 9, wherein the tetrafluoroethylene-based polymer contains 99.5 mol% or more of units based on tetrafluoroethylene with respect to all units contained in the polymer.   10. The tetrafluoroethylene-based polymer according to any one of claims 1 to 9, wherein units based on comonomer other than tetrafluoroethylene are more than 0.5 mol% with respect to all units contained in the polymer. Dispersion.   The tetrafluoroethylene-based 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. The dispersion according to any one of 1.   The dispersion according to any one of claims 1 to 12 is applied to the surface of a sheet base material to form a liquid film, and the liquid film is heated to obtain the powder and the acid-modified hydrocarbon-based polymer. A method for producing a sheet material, comprising: obtaining a sheet material having a layer containing the semi-cured product.   The manufacturing method according to claim 13, wherein the sheet material is an adhesive sheet using the layer as an adhesive layer between substrates.   The manufacturing method according to claim 13, wherein the sheet material is a coverlay film that adheres the layer to a printed wiring board so as to cover the metal wiring.