TW201927936A - Powder, powder paint, and laminate production method - Google Patents

Abstract

Provided are: a powder capable of readily forming a fluorine resin layer having a smooth surface; and a production method for a laminate using a powder paint including said powder. This powder comprises resin particles including a fluorine polymer having a unit based on tetrafluoroethylene and having a melting point of 260-320 DEG C. When D50 is X and D10 is Y, Y/X is no more than 0.3. Ideally, D10 is no more than 4 [mu]m and D50 is 15-60 [mu]m.

Description

Method for manufacturing powder, powder coating and laminated body

The present invention relates to a method for producing a powder, a powder coating material, and a laminated body containing fine particles.

BACKGROUND ART A fluoropolymer such as a copolymer (PFA) having a unit mainly composed of tetrafluoroethylene and a unit mainly composed of perfluoro (alkyl vinyl ether) has a low coefficient of friction, non-adhesion, and chemical resistance. Excellent heat resistance and other properties. Therefore, fluoropolymers are widely used in the surface processing of food industry products, kitchen appliances such as pans and pans, household products such as irons, electrical industrial products, and mechanical industrial products.

Patent Document 1 discloses a method of applying a powder coating material containing a powder composed of fluoropolymer particles to a substrate and firing to form a fluororesin layer, thereby obtaining a laminated body. Patent Document 2 discloses a powder that is a powder having excellent adhesion to a substrate, and the powder system is composed of a fluoropolymer particle having a functional group such as a carbonyl group-containing group.

Prior technical literature Patent literature
[Patent Document 1] International Publication No. 2011/048965
[Patent Document 2] International Publication No. 2016/017801

SUMMARY OF THE INVENTION Problems to be Solved by the Invention However, if the particle diameter of the resin particles constituting the powder is not adjusted, the surface of the formed fluororesin layer is prone to unevenness. The present inventors have found that the above phenomenon becomes apparent when a powder made of resin particles containing a high-melting fluoropolymer is fired to form a fluororesin layer.
An object of the present invention is to provide a powder capable of easily forming a smooth fluororesin layer, a powder coating material including the powder, and a method for manufacturing a laminated body using the powder coating material.

Means for Solving the Problems The present invention has the following aspects.
<1> A powder composed of resin particles containing a fluoropolymer having a unit mainly composed of tetrafluoroethylene and having a melting point of 260 to 320 ° C; and,
When the volume-based cumulative 50% particle diameter of the powder is set to X and the volume-based cumulative 10% particle diameter is set to Y, Y / X is 0.3 or less.
<2> The powder according to <1> has a volume-based cumulative 10% particle size of 4 μm or less and a volume-based cumulative 50% particle size of 15-60 μm.
<3> The powder according to <2>, when the amount of the resin particles having a particle diameter of 4 μm or less contained in the powder is A and the amount of the resin particles having a particle diameter of 15 to 60 μm is B, A / B is 0.1 or more.
<4> The powder according to <2> or <3>, wherein the amount of the resin particles having a particle diameter of 4 μm or less in the powder is 5 to 25% by volume.
<5> The powder according to any one of <1> to <4> has a cumulative 100% volume-based particle diameter of 220 μm or less.
<6> The powder according to any one of <1> to <5>, wherein the fluoropolymer has at least one selected from the group consisting of a carbonyl group-containing group, a hydroxyl group, an epoxy group, and an isocyanate group. Functional group.
<7> The powder according to <6>, wherein the fluoropolymer has the aforementioned unit mainly composed of tetrafluoroethylene and the unit having the aforementioned functional group.
<8> A powder coating material comprising the powder according to any one of <1> to <7>.
<9> The powder coating material according to <8>, wherein the amount of the powder contained in the powder coating material is 90 to 100% by mass.
<10> A method for manufacturing a laminated body, the laminated body having a base material and a fluororesin layer provided on the base material and formed of a powder such as any one of <1> to <7>;
The manufacturing method of the said laminated body is supplying the powder coating material containing the said powder to the said base material, and baking it, and obtaining the said fluororesin layer.
<11> The method according to <10>, wherein the firing of the powder coating material is performed by heating the melting point of the fluoropolymer or more.
The manufacturing method of <12> such as <10> or <11> whose thickness of the said fluororesin layer is 50-750 micrometers.

Advantageous Effects of Invention According to the present invention, a fluororesin layer having a smooth surface can be easily formed.

Forms for Carrying Out the Invention The definitions of the following terms apply to the scope of this specification and the patent application for inventions.
The "hot-melt polymer" refers to a polymer in a state where MFR is 0.01 to 1000 g / 10 minutes at a load of 49 N and at a temperature 20 ° C or higher than the melting point of the polymer.
"Polymer melting point" means a temperature corresponding to the maximum melting peak of a polymer measured by a differential scanning calorimetry (DSC) method.
The "MFR of the polymer" is a melt flow rate defined in JIS K 7210-1: 2014 (corresponding to the international standard ISO 1133-1: 2011).
"Volume-based cumulative 50% particle size (D50)" is a measurement of the particle size distribution of the powder by laser diffraction scattering method, and the total volume of the powder is set to 100% to obtain a cumulative curve. The particle diameter of the point where the cumulative volume is 50%.
Similarly, "Volume-based cumulative 10% particle size (D10)", "Volume-based cumulative 90% particle size (D90)" and "Volume-based cumulative 100% particle size (D100)" The volume-based cumulative 10% particle size, volume-based cumulative 90% particle size, and volume-based cumulative 100% particle size (maximum particle size).
That is, the D10, D50, D90, and D100 of the powder are particles that constitute the powder on a volume basis with a cumulative 10% particle size, a volume basis with a cumulative 50% particle size, a volume basis with a 90% particle size, and a volume basis with a 100% particle size .
A "unit mainly composed of a monomer" is a collective term for an atomic group formed directly by the polymerization of one molecule of a monomer and an atomic group obtained by chemically converting a part of the atomic group. In the present specification, a unit mainly composed of a monomer is simply referred to as a "unit".
"(Meth) acrylate" is a general term for acrylate and methacrylate. Similarly, "(meth) acrylic" is a general term for acrylic acid and methacrylic acid, and "(meth) acryloxy" is a general term for propyleneoxy and methacryloxy.

The resin particles constituting the powder of the present invention include a fluoropolymer (hereinafter also referred to as "F polymer") having a unit mainly composed of tetrafluoroethylene (hereinafter also referred to as "TFE unit") and having a melting point of 260 to 320 ° C. ).
The amount of the F polymer contained in the resin particles is preferably 80% by mass or more, preferably 85% by mass or more, more preferably 90% by mass or more, and even more preferably 100% by mass. When a powder composed of resin particles containing the F polymer in this amount is used, the non-adhesiveness, chemical resistance, and heat resistance of the formed fluororesin layer (hereinafter also referred to as "F resin layer") are improved. The F polymer may be used in combination of two or more.
Examples of other polymers include fluoropolymers other than F polymers, aromatic polyesters, polyamidoimines, and thermoplastic polyimides. Other polymers may be used in combination of two or more.

Examples of the F polymer include a tetrafluoroethylene-perfluoro (alkyl vinyl ether) copolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, an ethylene-tetrafluoroethylene copolymer, polydifluoroethylene, and polytrifluoro Vinyl chloride, ethylene-trifluorochloroethylene copolymer, and at least one functional group selected from the group consisting of a carbonyl group-containing group, a hydroxyl group, an epoxy group, and an isocyanate group (hereinafter also described as "Adhesive group") polymer, modified polytetrafluoroethylene. In addition, as long as it exhibits hot-melt property, polytetrafluoroethylene may be used as the F polymer.

Examples of modified polytetrafluoroethylene include: (i) a copolymer of tetrafluoroethylene (hereinafter also referred to as "TFE") and a trace amount of CH ₂ = CH (CF ₂ ) ₄ F; (ii) the above (i) A copolymer of) and a monomer having a trace amount of an adhesive group (hereinafter also referred to as "adhesive monomer"), (iii) a copolymer of TFE and a trace amount of an adhesive monomer, (iv ) Polytetrafluoroethylene having an adhesive group introduced by plasma treatment or the like, (v) Copolymer of (i) described above having an adhesive group introduced by plasma treatment or the like.

The melting point of the F polymer is 260 to 320 ° C, preferably 280 to 320 ° C, more preferably 295 to 315 ° C, and even more preferably 295 to 310 ° C. When the melting point of the F polymer is at least the above-mentioned lower limit value, the heat resistance of the F resin layer is improved. When the melting point of the F polymer is equal to or less than the above-mentioned upper limit value, the hot-meltability of the F polymer is improved.
The melting point of the F polymer can be adjusted according to the type or ratio of units constituting the F polymer, the molecular weight of the F polymer, and the like. For example, as the ratio of TFE units increases, the melting point of the F polymer tends to increase.

The MFR at a temperature higher than the melting point of the F polymer by 20 ° C or higher is preferably 0.1 to 1000 g / 10 minutes, preferably 0.5 to 100 g / 10 minutes, more preferably 1 to 30 g / 10 minutes, and even more preferably 5 to 20g / 10 minutes. When the MFR is equal to or more than the above lower limit value, the hot-melt property of the F polymer is further improved, and the appearance of the F resin layer is improved. When the MFR is equal to or less than the above upper limit value, the mechanical strength of the F resin layer is improved.
MFR is a standard for the molecular weight of F polymers. The larger the MFR, the smaller the molecular weight, and the smaller the MFR, the larger the molecular weight. The MFR of the F polymer can be adjusted according to the manufacturing conditions of the F polymer. For example, if the polymerization time is shortened when the monomers are polymerized, the MFR of the F polymer tends to increase.

From the viewpoint of excellent adhesion between the F resin layer and the substrate, it is preferable that the adhesive group is a carbonyl group-containing group.
Examples of the carbonyl-containing group include a hydrocarbon group having a carbonyl group between carbon atoms, a carbonate group, a carboxyl group, a haloformyl group, an alkoxycarbonyl group, and an acid anhydride residue (-C (O) -OC (O)- ), Polyfluoroalkoxycarbonyl, fatty acid residues.
From the viewpoint of further excellent adhesion between the F resin layer and the substrate, the carbonyl group-containing group is preferably a hydrocarbon group having a carbonyl group between carbon atoms, a carbonate group, a carboxyl group, a haloformyl group, and an alkoxy group. The carbonyl group and the acid anhydride residue are more preferably a carboxyl group and an acid anhydride residue.
Examples of the hydrocarbon group in the hydrocarbon group having a carbonyl group between carbon atoms include an alkylene group having 2 to 8 carbon atoms and the like. The carbon number of the alkylene group does not include the carbon number of the carbonyl group.
Examples of the haloformamyl group include -C (= O) -F and -C (= O) Cl.
Examples of the alkoxy group in the alkoxycarbonyl group include a methoxy group and an ethoxy group.

The adhesive group may be included in the F polymer as an adhesive unit, or may be included in a terminal of the F polymer main chain as a terminal group. When an adhesive group is included as an end group of the main chain, the F polymer may or may not include an adhesive unit.
The F polymer preferably includes a TFE unit and a unit mainly composed of an adhesive monomer (adhesive unit).
The adhesive group which the adhesive monomer has may be one or two or more. When there are two or more adhesive groups, the two or more adhesive groups may be the same or different, respectively.

Examples of the adhesive monomer include a monomer having a carbonyl group-containing group, a monomer having a hydroxyl group, a monomer having an epoxy group, and a monomer having an isocyanate group. From the viewpoint of excellent adhesion between the F resin layer and the substrate, the monomer having a carbonyl group-containing group is preferably used as the adhesive monomer.
Examples of the monomer having a carbonyl group include a cyclic monomer having an acid anhydride residue, a monomer having a carboxyl group, a vinyl ester, a (meth) acrylate, CF ₂ = CFOR ^f1 CO ₂ X ¹ (wherein , R ^f1 is a perfluoroalkylene group having 1 to 10 carbon atoms or a perfluoroalkylene group having 2 to 10 carbon atoms having an etheric oxygen atom between the carbon atoms, and X ¹ is a hydrogen atom or 1 to 3 carbon atoms alkyl).

Examples of the cyclic monomer having an acid anhydride residue include unsaturated dicarboxylic acid anhydrides. Examples of the unsaturated dicarboxylic anhydride include itaconic anhydride (hereinafter also referred to as "IAH"), citraconic anhydride (hereinafter also referred to as "CAH"), 5-norbornene-2,3-dicarboxylic anhydride ( Another name: Nadic acid anhydride. Hereinafter also referred to as "NAH"), maleic anhydride.
Examples of the monomer having a carboxyl group include unsaturated dicarboxylic acids (itaconic acid, citraconic acid, 5-norbornene-2,3-dicarboxylic acid, and maleic acid), and unsaturated monocarboxylic acids (such as Acrylic, methacrylic, etc.).
Examples of vinyl esters include vinyl acetate, vinyl chloroacetate, vinyl butyrate, trimethyl vinyl acetate, vinyl benzoate, and vinyl crotonic acid.
Examples of the (meth) acrylate include (polyfluoroalkyl) acrylate and (polyfluoroalkyl) methacrylate.

From the viewpoint of further improving the adhesion between the F resin layer and the substrate, the monomer having a carbonyl group-containing monomer is preferably a cyclic monomer having an acid anhydride residue, and more preferably IAH, CAH, or NAH. When IAH, CAH or NAH is used, an F polymer having an acid anhydride residue can be easily produced. From the viewpoint that the adhesion of the F resin layer is likely to be improved, the monomer having a carbonyl group-containing group is particularly preferably NAH.

Examples of the monomer having a hydroxyl group include vinyl esters having a hydroxyl group, vinyl ethers having a hydroxyl group, allyl ethers having a hydroxyl group, (meth) acrylates having a hydroxyl group, hydroxyethylcrotonate, and allyl alcohol.
Examples of the monomer having an epoxy group include unsaturated glycidyl ether (allyl glycidyl ether, 2-methylallyl glycidyl ether, vinyl glycidyl ether, etc.) ), Unsaturated glycidyl ester (glycidyl (meth) acrylate, etc.).
Examples of the monomer having an isocyanate group include 2- (meth) acryloxyethyl isocyanate, 2- (2- (meth) acryloxyethoxy) ethyl isocyanate, and 1,1- Bis ((meth) acryloxymethyl) ethyl isocyanate.
The adhesive monomer may be used in combination of two or more.

Examples of the unit other than the adhesive unit and the TFE unit include a unit mainly composed of perfluoro (alkyl vinyl ether) (hereinafter also referred to as "PAVE") (hereinafter also referred to as "PAVE unit"), A unit mainly composed of fluoropropylene (hereinafter also referred to as "HFP") (hereinafter also referred to as "HFP unit"), and a unit mainly composed of an adhesive monomer, TFE, PAVE, and monomers other than HFP.

Examples of PAVE include: 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, preferably PPVE.
PAVE can also be used in combination of two or more.

Examples of other monomers include other fluorinated monomers (except for adhesive monomers, TFE, PAVE, and HFP), and other non-fluorinated monomers (except for adhesive monomers).
Examples of other fluorine-containing monomers include vinyl fluoride, difluoroethylene, trifluoroethylene, trifluorochloroethylene, CF ₂ = CFOR ^f3 SO ₂ X ³ (wherein R ^f3 is perfluoro with 1 to 10 carbon atoms) An alkylene or perfluoroalkylene having 2 to 10 carbon atoms having an etheric oxygen atom between carbon atoms, X ³ is a halogen atom or a hydroxyl group), CF ₂ = CF (CF ₂ ) _p OCF = CF ₂ (where , P is 1 or 2), CH ₂ = CX ⁴ (CF ₂ ) _q X ⁵ (where X ⁴ is a hydrogen atom or a fluorine atom, q is an integer from 2 to 10, and X ⁵ is a hydrogen atom or a fluorine atom), Perfluoro (2-methylene-4-methyl-1,3-dioxetane). Other fluorine-containing monomers may be used in combination of two or more kinds.
Regarding CH ₂ = CX ⁴ (CF ₂ ) _q X ⁵ , 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, preferably CH ₂ = CH (CF ₂ ) ₄ F, and CH ₂ = CH (CF ₂ ) ₂ F.

Examples of other non-fluorine-containing monomers include ethylene and propylene, and ethylene is preferred. Other non-fluorinated monomers may be used in combination of two or more.
As for other monomers, other fluorine-containing monomers and other non-fluorine-containing monomers may be used in combination.

When the F polymer has an adhesive group at the end of the main chain as a terminal group, the adhesive group is preferably an alkoxycarbonyl group, a carbonate group, a carboxyl group, a fluoroformamyl group, an acid anhydride residue, or a hydroxyl group. The adhesive group can be introduced by appropriately selecting a radical polymerization initiator, a chain transfer agent, or the like used in the production of the F polymer.

From the viewpoint of improving the heat resistance of the F resin layer, the F polymer is preferably a copolymer having an adhesive unit, a TFE unit and a PAVE unit (hereinafter also referred to as a copolymer (A1)), an adhesive unit, and a TFE. The copolymer of the unit and the HFP unit (hereinafter also referred to as a copolymer (A2)) is preferably a copolymer (A1).

The copolymer (A1) may have at least one of HFP units and other units as necessary. That is, the copolymer (A1) may be a copolymer having an adhesive unit, a TFE unit, and a PAVE unit, or a copolymer having an adhesive unit, a TFE unit, a PAVE unit, and an HFP unit, or an adhesive unit The copolymer of TFE unit, TFE unit, PAVE unit and other units may also be a copolymer having adhesive units, TFE units, PAVE units, HFP units and other units.
From the viewpoint of further improving the adhesion between the F resin layer and the substrate, the copolymer (A1) is preferably a copolymer having a unit mainly composed of a monomer having a carbonyl group, a TFE unit, and a PAVE unit. A copolymer having a unit mainly composed of a cyclic monomer having an acid anhydride residue, a TFE unit and a PAVE unit is preferred.
Specific examples of the copolymer (A1) include: copolymers having TFE units, PPVE units and NAH units, copolymers having TFE units, PPVE units and IAH units, having TFE units, PPVE units and CAH units Of copolymers.
The ratio of the adhering units in the copolymer (A1) should preferably be 0.01 to 3 mol%, preferably 0.05 to 1 mol% in all the units constituting the copolymer (A1). In this case, it is easy to balance the adhesiveness between the F resin layer and the substrate, and the heat resistance and color of the F resin layer.
The ratio of the TFE units in the copolymer (A1) should preferably account for 90 to 99.89 mole%, preferably 96 to 98.95 mole% of all the units constituting the copolymer (A1). At this time, it is easy to balance the heat resistance, chemical resistance, and the like of the F resin layer, and the hot-meltability, stress crack resistance, and the like of the copolymer (A1).
The ratio of the PAVE units in the copolymer (A1) should preferably be 0.1 to 9.99 mol%, preferably 1 to 9.95 mol% in all the units constituting the copolymer (A1). In this case, it is easy to adjust the hot-melt property of the fluorocopolymer (A1).
The total of the adhesive unit, TFE unit and PAVE unit in the copolymer (A1) is preferably 90 mol% or more, and more preferably 98 mol% or more. The upper limit is 100 mol%.

The copolymer (A2) may have at least one of a PAVE unit and other monomer units as necessary. That is, the copolymer (A2) may be a copolymer having an adhesive unit, a TFE unit, and an HFP unit, or a copolymer having an adhesive unit, a TFE unit, an HFP unit, and a PAVE unit, or an adhesive unit The copolymer of TFE unit, TFE unit, HFP unit and other units may also be a copolymer having adhesive unit, TFE unit, HFP unit, PAVE unit and other units.
From the viewpoint of further improving the adhesion between the F resin layer and the substrate, the copolymer (A2) is preferably a copolymer having a unit mainly composed of a monomer having a carbonyl group, a TFE unit and an HFP unit. A copolymer having a unit mainly composed of a cyclic monomer having an acid anhydride residue, a TFE unit and an HFP unit is preferred.
Specific examples of the copolymer (A2) include: copolymers having TFE units, HFP units and NAH units, copolymers having TFE units, HFP units and IAH units, having TFE units, HFP units and CAH units Of copolymers.

The ratio of the adhering units in the copolymer (A2) should preferably account for 0.01 to 3 mol%, preferably 0.05 to 1.5 mol% of all the units constituting the copolymer (A2). In this case, it is easy to balance the adhesiveness between the F resin layer and the substrate, and the heat resistance and color of the F resin layer.
The ratio of the TFE units in the copolymer (A2) should preferably account for 90 to 99.89 mol%, preferably 92 to 96 mol% of all units constituting the copolymer (A2). At this time, it is easy to balance the heat resistance, chemical resistance, and the like of the F resin layer, and the hot-melt property, stress crack resistance, and the like of the copolymer (A2).
The ratio of the HFP units in the copolymer (A2) should preferably be 0.1 to 9.99 mol%, preferably 2 to 8 mol% in all the units constituting the copolymer (A2). When the ratio of the HFP units is within the above range, the thermal melting property of the copolymer (A2) is further improved.
The total ratio of the adhesive unit, TFE unit and HFP unit in the copolymer (A2) is preferably 90 mol% or more, and more preferably 98 mol% or more. The upper limit is 100 mol%.
The ratio of each unit in the F polymer can be determined by NMR analysis such as melting nuclear magnetic resonance (NMR) analysis, fluorine content analysis, and infrared absorption spectrum analysis. For example, as described in Japanese Patent Application Laid-Open No. 2007-314720, a ratio (mole%) of an adhesive unit among all units constituting the F polymer is determined using a method such as infrared absorption spectrum analysis.

As for the manufacturing method of the F polymer, it can be enumerated: (i) a method of polymerizing an adhesive monomer and TFE and optionally added PAVE, FEP, and other monomers; (ii) a method having a TFE unit and A method for heating a fluorinated copolymer that decomposes a functional unit of a bonding group to thermally decompose the functional group to generate a bonding group (for example, a carboxyl group); (iii) graft polymerizing a fluorinated copolymer having a TFE unit The method of the sex monomer is preferably the method of (i) above.
The polymerization method (bulk polymerization method, solution polymerization method, suspension polymerization method, emulsion polymerization method, etc.) is not particularly limited, and can be appropriately set. The amount and type of the solvent, polymerization initiator, and chain transfer agent used in the polymerization may be appropriately set. In addition, the polymerization conditions (temperature, pressure, time, etc.) can be appropriately set depending on the type of monomer used.

In the powder of the present invention, when D50 is set to X and D10 is set to Y, Y / X is 0.3 or less. That is, the powder of the present invention includes resin particles having a moderate particle size (hereinafter also referred to as "medium particles") and resin particles having a particle size sufficiently smaller than the medium particles (hereinafter also referred to as "fine particles").
The F resin film is formed by supplying powder onto a substrate to form a powder layer, and then firing the powder layer. At this time, as shown in FIG. 1 (a), a space is formed between the intermediate particles in the powder layer, and the space is filled with fine particles. Therefore, when the powder layer is fired, as shown by the thick line in FIG. 1 (b), the surface of the powder layer (medium particles and fine particles) will start to melt almost uniformly, and an F resin layer with a smooth surface is easily formed. .

On the other hand, if fine particles are not included, as shown in FIG. 2 (a), there are many voids formed between the intermediate particles in the powder layer. Therefore, when the powder layer is fired, as shown by the thick line in FIG. 2 (b), the surface of the powder layer will start to melt along the shape of the medium particles, and it is easy to form the surface with irregularities reflecting the shape of the medium particles. F resin layer.
An F polymer having an adhesive group suitable for use in the present invention tends to have a higher MFR than an F polymer having no adhesive group. Therefore, the F polymer having an adhesive group is difficult to flow even if it is melted during firing, and an uneven shape is liable to remain on the surface of the F resin layer. In this case, the effect of the present invention using powder containing fine particles is particularly high.

In the present invention, Y / X is preferably 0.25 or less, and more preferably 0.15 to 0.2. When Y / X is within the above range, fine particles can more surely fill the spaces formed between the intermediate particles in the powder layer. As a result, an F resin layer having a smoother surface can be formed. In addition, Y / X is a value of Y divided by X.
More specifically, it is preferable that D10 is 4 μm or less and D50 is 15 to 60 μm. When D10 and D50 of the powder are adjusted within the above range, a smooth and thin F resin layer can be easily formed regardless of whether the F polymer has an adhesive group or not.

The D10 of the powder is preferably 0.5 to 3.9 μm, and more preferably 2 to 3.9 μm. When D10 is below the above-mentioned upper limit value, an F resin layer having a smoother surface can be easily formed. When D10 is at least the above lower limit value, it is difficult for the powder to adhere to the nozzle when the powder coating material containing the powder is applied, and the workability during the coating is improved.
The D50 of the powder is preferably 17 to 50 μm, and more preferably 20 to 40 μm. If D50 is more than the said lower limit value, it becomes easy to form a thinner F resin layer. When D50 is below the above upper limit value, it is easy to form an F resin layer having a smoother surface.

The D100 of the powder is preferably 220 μm or less, preferably 100 to 210 μm, and more preferably 140 to 205 μm. When D100 is equal to or less than the above upper limit, the powder does not include resin particles having an excessively large particle size relative to the medium particles (hereinafter also referred to as "coarse particles"), and therefore it is easy to form an F resin layer having a smoother surface. When D100 is at least the above lower limit value, it is easy to form an F resin layer having a sufficient thickness.

When the amount of resin particles having a particle diameter of 4 μm or less in the powder is A and the amount of resin particles having a particle diameter of 15 to 60 μm is B, A / B is preferably 0.1 or more, and more preferably 0.2 or more. A / B is preferably 0.5 or less, and more preferably 0.4 or less. If the A / B satisfies the above range, fine particles can be filled in the powder layer with a higher density to fill the spaces formed between the intermediate particles. The A / B is the value of A divided by B.
The specific amount of the resin particles having a particle diameter of 4 μm or less in the powder is preferably 5 to 25% by volume, and more preferably 10 to 20% by volume. When resin particles having a particle diameter of 4 μm or less are contained in this amount, even when the powder contains coarse particles, it is easy to form an F resin layer with a smooth surface.

The above powder can be produced by the following methods: (i) a method of obtaining F polymer by solution polymerization method, suspension polymerization method or emulsion polymerization method, and then removing the organic solvent or aqueous medium to obtain powder and then classifying the powder; ii) A method of melt-kneading the F polymer and other ingredients added if necessary, pulverizing the kneaded material, and classifying the pulverized material if necessary.
The powder can also be produced by mixing a first powder having D50 as the X and a second powder having D50 as the Y in a specific ratio. The first powder and the second powder can be produced by the method (i) or (ii).

D10 and D50 of the powder can be adjusted by the type of the grinding method and the grinding conditions.
Regarding the pulverizing method, a rotor mill, a nail disc mill, a hammer mill, a freezing hammer mill, a roller mill, a screen mill, a vibration mill, a sand mill, a vortex mill, a ball mill, and a basket mill Machine and other methods of crushing. Among them, from the viewpoint of easily adjusting the D10 and D50 of the powder to the above range, a method using a rotor mill and a nail disc mill is preferred.
If the number of revolutions of the pulverizer is reduced, D10 and D50 tend to increase. If the number of revolutions of the pulverizer is high and the pulverization time is long, D10 and D50 tend to become smaller.

The powder coating material of the present invention is a powder coating material including the powder of the present invention.
The manufacturing method of the laminated body of this invention is to supply the powder coating material containing the powder of this invention to a base material, and baking is performed, and an F resin layer is formed. Thereby, the laminated body which has a base material and the F resin layer provided on the base material and formed from a powder coating material can be obtained.
The powder coating may optionally contain other ingredients than the powder of the present invention. Examples of the other components include pigments, carbon fibers, and graphite.
The amount of the powder of the present invention contained in the powder coating is preferably 90% by mass or more, and more preferably 95% by mass or more. The upper limit of the amount of the powder of the present invention contained in the powder coating is 100% by mass.

Examples of the substrate include household items such as pans, pans, irons, and piping in factories.
Examples of the material of the substrate include metals such as stainless steel and iron, resins, glass, and ceramics.
Regarding the supply method of powder coating, electrostatic coating is preferred.

The firing of the powder coating material is preferably performed by heating above the melting point of the F polymer. The specific firing temperature is preferably 350 to 380 ° C, preferably 350 to 375 ° C, and more preferably 350 to 370 ° C. When the firing temperature is equal to or higher than the above-mentioned lower limit value, it is easy to form an F resin layer with a smooth surface, and the adhesion between the F resin layer and the substrate is improved.
On the other hand, if the firing temperature is equal to or lower than the above-mentioned upper limit value, since the melting point of the F polymer in the present invention is 260 to 320 ° C., it is possible to prevent gas generation due to thermal decomposition of the F polymer. Therefore, foaming or cracking in the F resin layer can be suppressed, and a laminated body having high safety and excellent appearance can be easily obtained. In other words, when an F polymer having a melting point of 260 to 320 ° C is used, it is impossible to extremely increase the firing temperature, and the powder layer has to be fired at a lower temperature. The powder of the present invention can easily obtain an F resin layer with a smooth surface even if it is fired at a relatively low temperature by containing fine particles.

The firing time is preferably 1 to 20 minutes, and more preferably 1 to 15 minutes. When the firing time is equal to or more than the above lower limit value, it is easy to form an F resin layer having a smooth surface. When the firing time is equal to or less than the above upper limit value, it is easier to suppress foaming or cracking in the F resin layer.

In the present invention, the operation of supplying the powder coating material to the substrate and firing it may be repeated twice or more.
At this time, the firing temperature and firing time in each firing step may be different or the same. At this time, the total firing time is preferably 3 to 60 minutes, preferably 4 to 60 minutes, more preferably 5 to 45 minutes, and even more preferably 10 to 30 minutes. When the total firing time is equal to or less than the above upper limit value, it is easy to suppress the occurrence of foaming or cracking in the F resin layer. When the total firing temperature is equal to or higher than the above-mentioned lower limit value, it is easy to form an F resin layer having a smooth surface, and the adhesion between the F resin layer and the substrate is further improved.

The thickness of the F resin layer to be formed is preferably 50 to 750 μm, and more preferably 100 to 500 μm. When the thickness of the F resin layer is equal to or more than the above-mentioned lower limit value, the productivity of the laminated body is improved. When the thickness of the F resin layer is equal to or less than the above upper limit value, the chemical resistance of the F resin layer is improved.

The peel strength of the F resin layer and the substrate is preferably 14 N / cm or more, preferably 15 to 100 N / cm, more preferably 16 to 90 N / cm, and even more preferably 16 to 85 N / cm. When the peel strength between the F resin layer and the substrate is at least the above lower limit value, it means that the adhesion between the F resin layer and the substrate is high, and the F resin layer is difficult to peel from the substrate.

As mentioned above, the manufacturing method of the powder and laminated body of this invention was demonstrated, However this invention is not limited to the structure of the said embodiment.
For example, the powder of the present invention may be added with another arbitrary structure to the structure of the aforementioned embodiment, or may be replaced with an arbitrary structure that can perform the same function.
In addition, the method for producing a laminated body according to the present invention may have other arbitrary steps added to the configuration of the embodiment described above, or may be replaced with an arbitrary step capable of producing the same effect.

[Example]
The following examples illustrate the present invention in detail, but the present invention is not limited to these examples.

1. Manufacture of raw material powder
[Manufacturing example 1]
Using NAH, TFE, and PPVE, a raw material powder (A1) composed of an F polymer (1) was produced according to a procedure described in paragraph [0123] of International Publication No. 2016/017801.
The ratio (mole%) of NAH units, TFE units, and PPVE units contained in the F polymer (1) was 0.1, 97.9, and 2.0 in this order. The melting point of the F polymer (1) was 300 ° C., the MFR was 17.6 g / 10 minutes, and the D50 of the raw material powder (A1) was 1554 μm.

[Manufacturing example 2]
A raw material powder (A2) composed of an F polymer (2) was obtained in the same manner as in Production Example 1 except that the chain transfer agent was changed to 0.5 kg of methanol.
The ratios (mole%) of NAH units, TFE units, and PPVE units contained in the F polymer (2) were 0.1, 97.9, and 2.0 in this order. The melting point of the F polymer (2) was 300 ° C., the MFR was 25.0 g / 10 minutes, and the D50 of the raw material powder (A2) was 1570 μm.

[Manufacturing example 3]
A raw material powder (A3) composed of an F polymer (3) was obtained in the same manner as in Production Example 1 except that the chain transfer agent was changed to 0.35 kg of methanol.
The ratios (mole%) of NAH units, TFE units, and PPVE units contained in the F polymer (3) were 0.1, 97.9, and 2.0 in this order. The melting point of the F polymer 3 was 300 ° C., the MFR was 8.2 g / 10 minutes, and the D50 of the raw material powder (A3) was 1490 μm.
The ratio of each unit contained in the F polymer is measured by a method described in International Publication No. 2016/017801.
The melting point was measured using a differential scanning thermal analyzer (DSC-7020) manufactured by Seiko Instruments Inc. The temperature rise rate of the F polymer was 10 ° C / min.
The MFR was determined by measuring the mass (g) of the F polymer flowing out of a nozzle having a diameter of 2 mm and a length of 8 mm for 10 minutes (unit time) under a load of 372 ° C and 49 N at a melt index measuring machine manufactured by Techno Seven.
The D50 of the raw material powder was obtained by the following procedure.
From top to bottom, they are sequentially overlapped as follows: 2.000 mesh (mesh aperture 2.400mm), 1.410 mesh (mesh aperture 1.705mm), 1.000 mesh (mesh aperture 1.205mm), 0.710 mesh (mesh aperture 0.855mm), 0.500 Screen (mesh aperture 0.605mm), 0.250 screen (mesh aperture 0.375mm), 0.149 screen (mesh aperture 0.100mm) and receiving tray.
Put the raw powder into the top sieve and sieve with a shaker for 30 minutes. The mass of the raw material powder remaining on each sieve was measured, and the cumulative value of the passing mass with respect to the pore size of each mesh was represented in a graph. The particle diameter that had accumulated to 50% by the mass was determined as D50 of the raw powder.
2. Manufacturing of powders and laminates
[example 1]
First, a raw material powder (A1) was pulverized using a rotor mill (Fritsch Co., high-speed rotor pulverizer P-14) at a speed of 1700 rpm to obtain a pulverized powder.
Next, the pulverized powder was classified using a circular vibrating sieve (manufactured by SEISHIN Corporation, KGO-1000 type, mesh opening 212 μm) to obtain a powder (B1).
The powder (B1) had D10 of 3.8 μm, D50 of 22.2 μm, D90 of 100.6 μm, D100 of 200.5 μm, a loose filler density of 0.491 g / mL, and a dense filler density of 0.646 g / mL.

First, a SUS304 steel plate having a length of 40 mm, a width of 150 mm, and a thickness of 2 mm was prepared.
Next, a 60-mesh alumina particle was used, and the steel plate surface was sand-blasted so that surface roughness Ra might become 5-10 micrometers.
Then, the surface of the steel plate was cleaned with ethanol to prepare a substrate.
After the powder coating material consisting of powder (B1) was electrostatically coated on the surface of the substrate, the firing operation was repeated 10 times at a firing temperature of 350 ° C. for 4 minutes to obtain a laminate.
The thickness of the F resin layer formed on the substrate was 314 μm.

[Example 2]
First, a raw material powder (A2) was pulverized using a nail disc mill (manufactured by SEISHIN Corporation, M-4 type) at a speed of 5000 rpm to obtain a pulverized powder.
Next, the pulverized powder was classified using a circular vibrating screen machine (KGO-1000 type manufactured by SEISHIN Corporation, with a mesh opening of 212 μm) to obtain a powder (B2).
D10 of the powder (B2) was 3.6 μm, D50 was 21.1 μm, D90 was 99.4 μm, D100 was 181.9 μm, the density of the loose filler was 0.524 g / mL, and the density of the compact filler was 0.695 g / mL.
Next, the base material produced in the same manner as in Example 1 was electrostatically coated with a powder coating made of powder (B2), and then repeatedly fired at a firing temperature of 350 ° C for 6 minutes. To get a laminated body.
The thickness of the F resin layer formed on the substrate was 330 μm.

[Example 3]
A powder (B3) was obtained in the same manner as in Example 2 except that the raw material powder (A3) was used instead of the raw material powder (A2).
The powder (B3) had D10 of 3.9 μm, D50 of 24.4 μm, D90 of 78.2 μm, D100 of 169.9 μm, a loose filler density of 0.525 g / mL, and a dense filler density of 0.699 g / mL.
Next, the surface of the substrate produced in the same manner as in Example 1 was electrostatically coated with a powder coating made of powder (B3), and then repeatedly fired at a firing temperature of 350 ° C. for a firing time of 4 minutes. Further, after the above-mentioned powder coating was electrostatically coated, the firing operation was performed once at a firing temperature of 350 ° C. for a firing time of 6 minutes to obtain a laminated body.
The thickness of the F resin layer formed on the substrate was 330 μm.

[Example 4]
A powder (B4) was obtained in the same manner as in Example 2 except that the number of revolutions of the nail disc mill was changed to 2100 rpm without classification.
Further, the powder (B4) had D10 of 10.6 μm, D50 of 94.4 μm, D90 of 260.1 μm, D100 of 340.1 μm, a loose filler density of 0.729 g / mL, and a dense filler density of 0.835 g / mL.
Next, a laminated body was obtained in the same manner as in Example 3 except that the powder coating material composed of the powder (B4) was used.
The thickness of the F resin layer formed on the substrate was 330 μm.

[Example 5]
A powder (B5) was obtained in the same manner as in Example 2 except that the number of revolutions of the nail disc mill was changed to 2100 rpm.
The powder (B5) had D10 of 10.6 μm, D50 of 82.1 μm, D90 of 186.5 μm, D100 of 212.0 μm, a loose filler density of 0.511 g / mL, and a dense filler density of 0.672 g / mL.
Next, a laminated body was obtained in the same manner as in Example 3 except that a powder coating material composed of powder (B5) was used.
The thickness of the F resin layer formed on the substrate was 330 μm.

[Example 6]
A powder (B6) was obtained in the same manner as in Example 2 except that the number of revolutions of the nail disc mill was changed to 3000 rpm.
D10 of the powder (B6) was 9.2 μm, D50 was 56.9 μm, D90 was 131.6 μm, D100 was 203.2 μm, the density of the loose filler was 0.529 g / mL, and the density of the compact filler was 0.691 g / mL.
Next, a laminated body was obtained in the same manner as in Example 3 except that a powder coating material composed of powder (B6) was used.
The thickness of the F resin layer formed on the substrate was 330 μm.

[Example 7 (comparative example)]
A powder (B7) and a laminate were obtained in the same manner as in Example 2 except that the number of revolutions of the nail disc mill was changed to 4000 rpm.
The powder (B7) had D10 of 8.3 μm, D50 of 25.5 μm, D90 of 120.6 μm, D100 of 191.3 μm, a loose filler density of 0.503 g / mL, and a dense filler density of 0.657 g / mL.
The thickness of the F resin layer formed on the substrate was 330 μm.

The particle diameter and amount of the resin particles constituting the powder, the density of the loose filler and the density of the tight filler are measured as follows.
(Measurement of Particle Size and Amount of Resin Particles)
The powder was dispersed in water using a laser diffraction scattering particle size distribution measuring device (LA-920 measuring device) manufactured by Horiba, Ltd., and the particle size distribution was measured to calculate D10, D50, D90, and D100.
Further, the amount of resin particles having a particle diameter of 4 μm or less and the amount of resin particles having a particle diameter of 15 to 60 μm were obtained from the obtained particle size distribution chart.
(Loose packing density and tight packing density)
The bulk density and bulk density of the powder are measured using the methods described in [0117] and [0118] of International Publication No. 2016/017801, respectively.

3. Measurement and evaluation
3-1. Peeling strength First, 10 mm of cuts were formed from the F resin layer surface side of the laminated body obtained in each example using a cutter.
Next, a part of the F resin layer was peeled off and fixed to a chuck of a tensile tester.
Then, the peeling strength (N / cm) when the F resin layer was peeled from the substrate at a tensile speed of 50 mm / minute and 90 ° was measured.

3-2. Appearance Evaluation 100 laminates were produced in each example, the surface of the F resin layer of each laminate was visually confirmed, and the appearance was evaluated by the following evaluation criteria.
＜ Evaluation criteria ＞
：: No unevenness was observed on the surface of the F resin layer of any laminated body.
：: Unevenness was observed on the surface of the F resin layer of 5 or less laminates.
Δ: Unevenness was observed on the surface of the F resin layer of 6 to 10 laminates.
╳: Unevenness was observed on the surface of the F resin layer of more than 10 laminates.
The above results are shown in Table 1 together with the powder manufacturing conditions, particle size (D10, D50, D90, D100) and amount, and the manufacturing conditions of the laminated body.

[Table 1]

As shown in Table 1, in Examples 1 to 6 in which the powder having a relationship between D10 and D50 within the range specified in the present invention was used, the adhesiveness between the substrate and the F resin layer was excellent.
In Examples 1 to 3 using a powder with a smaller D50, an F resin layer having a smooth surface was formed. On the other hand, in Examples 4 to 6 using a powder with a larger D50, there were irregularities on the surface of the F resin layer. tendency.
In Example 7 where powders whose relationship between D10 and D50 deviated from the range specified in the present invention were used, unevenness was observed on the surface of the F resin layer. Moreover, there exists a tendency for the adhesiveness of a base material and an F resin layer to fall.

Industrial Applicability The powder of the present invention is suitable for a powder coating used for powder coating, and is particularly suitable for a powder coating used to form a thick fluororesin layer with a smooth surface.
In addition, the entire contents of the Japanese Patent Application No. 2017-235350 specification, patent application scope, abstract, and drawings, which will be filed on December 07, 2017, are hereby incorporated by reference as the content of the present specification.

FIG. 1 is a diagram for explaining a state change when a fluororesin layer is formed using the powder of the present invention.

FIG. 2 is a diagram for explaining a state change when a fluororesin layer is formed using a conventional powder.

Claims (12)

A powder composed of resin particles containing a fluoropolymer having a unit mainly composed of tetrafluoroethylene and having a melting point of 260 to 320 ° C; and, When the volume-based cumulative 50% particle diameter of the powder is set to X and the volume-based cumulative 10% particle diameter is set to Y, Y / X is 0.3 or less. For example, the powder of claim 1 has a volume-based cumulative 10% particle size of 4 μm or less and a volume-based cumulative 50% particle size of 15-60 μm. As in the powder of claim 2, when the amount of resin particles having a particle size of 4 μm or less in the powder is set to A and the amount of resin particles having a particle size of 15 to 60 μm is set to B, A / B is Above 0.1. For example, the powder of claim 2 or 3, wherein the powder contains 5 to 25% by volume of the aforementioned resin particles having a particle diameter of 4 μm or less. For example, the powder according to any one of claims 1 to 4 has a cumulative 100% particle size on a volume basis of 220 μm or less. The powder according to any one of claims 1 to 5, wherein the fluoropolymer has at least one functional group selected from the group consisting of a carbonyl-containing group, a hydroxyl group, an epoxy group, and an isocyanate group. The powder according to claim 6, wherein the aforementioned fluoropolymer has the aforementioned unit mainly composed of tetrafluoroethylene and the unit having the aforementioned functional group. A powder coating comprising the powder according to any one of claims 1 to 7. According to the powder coating of claim 8, the amount of the powder contained in the powder coating is 90 to 100% by mass. A method for manufacturing a laminated body, the laminated body having a base material and a fluororesin layer provided on the base material and formed of the powder according to any one of claims 1 to 7; The manufacturing method of the said laminated body is supplying the powder coating material containing the said powder to the said base material, and baking it, and obtaining the said fluororesin layer. The method according to claim 10, wherein the firing of the powder coating material is performed by heating the melting point of the fluoropolymer or more. The manufacturing method according to claim 10 or 11, wherein the thickness of the foregoing fluororesin layer is 50 to 750 μm.