JP2014118458A - Powder coating and coating member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a powder coating capable of adjusting glossiness in the surface of a cured coating film in a wide range, and a coating member coated by using the powder coating.SOLUTION: A powder coating is obtained by mixing two or more kinds of powder different in the concentration of a pigment by 5 points or more, by wt.% value. The powder coating is preferably obtained by mixing powder of polyester resin containing a pigment and powder of fluorine resin containing a pigment. The concentration of a pigment in the powder of fluorine resin may be higher or lower than the concentration of a pigment in the powder of polyester resin. A coating member comprises a coating film formed by electrostatic coating and baking using the powder coating.

Description

  The present invention relates to a powder coating obtained by mixing a plurality of powders, and more particularly to a powder coating capable of adjusting glossiness widely. The present invention also relates to a painted member such as a painted building material coated with the powder paint.

  Many solvent-based fluororesin coatings are used for the surface finishing of aluminum alloy building exterior materials that require long-term durability. However, in recent years, a powder coating containing no solvent has been attracting attention due to environmental problems caused by VOC emissions.

  As a method of electrostatically coating aluminum building materials such as aluminum sashes, aluminum curtain walls, aluminum verticals, and aluminum gates using powder, electrostatic coating is performed by using a powder paint blended with polyester paint and fluorine paint. A film is formed (Patent Documents 1 to 3).

  As a method for adjusting the glossiness of the powder coating film, there is a method of adding a coarse particle extender pigment (Patent Document 1). In this method, the 60 ° specular reflectance (60 ° gloss) is 50 or less. However, the physical properties of the coating film are significantly deteriorated due to the addition of a large amount of extender pigments. For example, when an extender is added in an amount of 30 wt% or more, the coating film becomes hard and brittle, and the appearance defect, water resistance, and weather resistance are remarkably lowered.

  Patent Document 2 describes a polyester / fluororesin coating film in which a polyester paint is distributed richly on the base side and a fluorine paint is distributed richly on the film surface side, but the pigment concentrations in the two paints are different. There is no description about the point to be applied, and the glossiness is in a narrow range of 25 to 40%.

  Patent Document 3 describes a powder coating that dry blends two types of fluorine-containing resin particles having different combinations of a fluorine-containing resin and a curing agent to arbitrarily adjust the 60-degree specular gloss to 30 to 60%. However, there is no description of different pigment concentrations in both resins.

JP 61-19668 JP2012-40503 JP2003-183591

  An object of this invention is to provide the powder coating material which can adjust the glossiness of the cured coating-film surface in the wide range, and the coating member coated using this powder coating material.

The powder coating material of the present invention is obtained by mixing two or more types of resin powders having a pigment concentration (wt% value) that differs by 5 points or more.
In one embodiment of the present invention, the powder coating is obtained by dry blending a polyester resin powder coating containing a pigment and a fluororesin powder coating containing a pigment, and the pigment concentration of the fluororesin powder coating is a polyester resin powder. It is higher than the pigment concentration of body paint.
In another aspect of the present invention, the powder coating is obtained by dry blending a polyester resin powder coating containing a pigment and a fluororesin powder coating containing a pigment, and the polyester resin powder coating has a pigment concentration of fluorine. It is higher than the pigment concentration of the resin powder paint.

  In the case of these aspects, it is preferable that (DELTA) SP value of a polyester resin and a fluororesin is 1.0-1.5.

  Further, in the powder coating obtained by dry blending 60 to 80 wt% of the polyester resin powder coating and 20 to 40 wt% of the fluororesin powder coating, the pigment concentration contained in the polyester resin powder coating is 50 wt% or less, It is preferable that the pigment concentration contained in the fluororesin powder coating is 50 wt% or less.

  The coating member of the present invention has a coating film formed by electrostatic coating and baking using the powder coating of the present invention.

  According to the powder coating material of the present invention, the glossiness can be widely adjusted by combining powders having different pigment concentrations.

  The polyester resin and fluororesin have a fluororesin component on the coating surface side when melted during the thermosetting process to form a coating film due to chemical characteristics, especially differences in SP value and melt viscosity. It will be easy to exist. For this reason, by varying the pigment concentration of the polyester resin powder and the fluororesin powder, the viscosity behavior at the time of heating and melting is greatly changed, and the surface roughness of the cured coating film can be adjusted. When the surface roughness is large, the glossiness decreases due to diffuse reflection of light, and when the surface roughness is small, it becomes close to specular reflection and the glossiness increases. Accordingly, by adjusting the blending ratio of the polyester resin powder and the fluororesin powder and the concentration of each pigment, the glossiness of the coating film can be widely adjusted.

  By using polyester resin powder and fluororesin powder as the powder, the coating film has good durability.

  The powder coating material of the present invention is obtained by mixing two or more kinds of resin powders having a pigment concentration (wt% value) of 5 points or more, preferably polyester resin powder and fluororesin powder having different pigment concentrations. It is a mixture of the body. In addition, resin powder other than polyester resin powder and fluororesin powder may be contained, and this resin may contain a pigment.

  The fluororesin used in the present invention is a resin that is solid at room temperature, and preferably has a softening point of 50 to 150 ° C.

<Fluorine resin>
The fluororesin is a fluorine-containing copolymer obtained by polymerizing (or copolymerizing) a fluorine-containing monomer, and the following fluorine-containing monomer is used.

Examples of the fluorine-containing monomer include vinyl fluoride, vinylidene fluoride, trifluoroethylene, tetrafluoroethylene, bromotrifluoroethylene, chlorotrifluoroethylene, pentafluoropropylene, hexafluoropropylene, and (per) fluoroalkyltrifluoro. Vinyl ether [(per) fluoroalkyl group has 1 to 18 carbon atoms. ] And the like are typical examples.
The fluororesin may be obtained by copolymerizing a polymerizable monomer other than the above-mentioned fluorine-containing monomer. Examples of the polymerizable monomer include vinyl ethers, olefins, allyl ethers, vinyl esters, allyl esters, (meta ) Acrylic acid esters, crotonic acid esters and the like.
The fluororesin may have a reactive site that reacts with a curing agent or the like, and may be a copolymer with a reactive group-containing monomer together with the above-mentioned fluorine-containing monomer or polymerizable monomer.
Examples of the reactive group include functional groups such as hydroxyl group, carboxyl group, amide group, amino group, nitrile group, glycidyl group, and isocyanate group.
Among these, it is preferable to use a hydroxyl group-containing fluororesin using a hydroxyl group-containing monomer from the viewpoints of stability of the resin and control of melt viscosity.

<Polyester resin>
The polyester resin used in the present invention is a resin obtained by reacting a carboxylic acid and a polyhydric alcohol, and is a solid resin at room temperature. The softening point is preferably 100 to 150 ° C.

Examples of carboxylic acid components that can be used in the production of polyester resins include phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,2-octadecanedicarboxylic acid, maleic acid, fumaric acid, cyclohexanedicarboxylic acid, hexahydrophthalic acid, tetrahydrophthalic acid , Polycarboxylic acids such as trimellitic acid and pyromellitic acid, lower alkyl esters of these polyvalent carboxylic acids and their anhydrides, or hydroxy such as malic acid, tartaric acid, 1,2-hydroxystearic acid, paraoxybenzoic acid, etc. Carboxylic acid can be mentioned .
Examples of the polyhydric alcohol component that can be used in the production of the polyester resin include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, , 4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, 1,10-decanediol, neopentyl glycol, spiroglycol, 1,10-decanediol, 1, 4-Cyclohexanedimethanol, trimethylolethane, trimethylolpropane, glycerin, pentaerythritol and the like can be mentioned.

<Pigment>
As for the pigment, color pigments, extender pigments, luster pigments, rust preventive pigments and the like used in general powder coatings can be used.
Examples of the color pigment include inorganic pigments such as titanium oxide, yellow iron oxide, titanium yellow, and red rose, and organic pigments such as cyanine blue, cyanine green, permanent yellow FGL, permanent red F5RK, carbazole, quinacridone red, and carbon black. Etc.
Examples of extender pigments include barium sulfate, barium carbonate, calcium carbonate, silica, talc, and alumina.
Examples of the bright pigment include aluminum powder pigment, nickel powder pigment, stainless powder pigment, copper powder, bronze powder, gold powder, silver powder, mica pigment, graphite pigment, glass flake pigment, and flaky iron oxide pigment. .
Examples of rust preventive pigments include condensed calcium phosphate, aluminum phosphate, condensed aluminum phosphate, zinc phosphate, aluminum phosphite, zinc phosphite, calcium phosphite, zinc molybdate, calcium molybdate, and manganese molybdate. Can be mentioned.

  The pigments in the polyester resin powder and the fluororesin powder preferably have the same composition. The pigment concentration of the polyester resin powder and the fluororesin powder is preferably about 3 to 50 wt%. When the pigment concentration is excessively low, the coloring effect and the gloss adjusting effect are poor, and when the pigment concentration is excessively high, the properties of the coating film are deteriorated.

  The polyester resin powder and fluororesin powder have different pigment concentrations (wt% values) of 5 points or more, preferably 10 points or more, for example, 10 to 50 points. Thus, by varying the pigment concentration in both powders and adjusting the blending ratio of the polyester resin powder and the fluororesin powder and the concentration of each pigment, the glossiness of the coating film can be widely adjusted. . In this specification, the difference (ab) value between the pigment concentration awt% and bwt% is expressed as a point. For example, the difference between 50 wt% and 40 wt% is 10 points.

<Epoxy resin>
The powder coating composition of the present invention may further contain (D) an epoxy resin in addition to the components (A) fluororesin, (B) polyester resin, and (C) pigment. This epoxy resin is added in an amount of 1 to 5 parts by mass in order to improve the adhesion to the substrate.
The epoxy resin used in the present invention is a resin that is solid at room temperature, and the softening point of the resin is preferably 50 to 150 ° C. As such an epoxy resin, an epoxy resin conventionally used for producing an epoxy resin powder coating can be used without particular limitation.
Specifically, for example, bisphenol A type diglycidyl ether resin, bisphenol F type diglycidyl ether resin, aminoglycidyl ether resin, bisphenol AD type diglycidyl ether resin, bisphenol Z type diglycidyl ether resin, O-cresol novolac epoxy Resin, phenol novolac epoxy resin, biphenol glycidyl ether resin, cyclopentadiene skeleton epoxy resin, naphthalene skeleton epoxy resin, GMA acrylic resin, etc., or those in which substituents of these resins are replaced with other ones, for example, CTBN or esterification Those subjected to modification such as can be used without limitation.

<Curing agent>
The curing agent used in the present invention is not particularly limited as long as it reacts with the above (A) fluororesin, (B) polyester resin, and (D) epoxy resin to form a cross-linked bond. Various curing agents that are used can be used. In particular, the curing agent is preferably an isocyanate compound from the viewpoint of coating film properties such as coating film hardness and hydrolysis resistance, and more preferably a blocked isocyanate compound.
In the present invention, the preferred blocked isocyanate as a curing agent is solid at room temperature. Examples of the isocyanate include polyisocyanate obtained by reacting an aliphatic, aromatic, and araliphatic diisocyanate with a low-molecular compound having active hydrogen, by reacting with a blocking agent and masking. It is manufactured and its manufacture is easy. Examples of the diisocyanate used here include tolylene diisocyanate, 4,4′-diphenylmethane isocyanate, xylylene diisocyanate, hexamethylene diisocyanate, 4,4′-methylene bis (cyclohexyl isocyanate), methylcyclohexane diisocyanate, bis (isocyanate). Methyl) cyclohexane, isophorone diisocyanate, dimer acid diisocyanate, lysine diisocyanate and the like.
Other additives include plasticizers, curing accelerators, crosslinking accelerators, surface conditioners, UV absorbers, light stabilizers, antioxidants, fluidity modifiers, anti-sagging agents, and anti-foaming agents that are additives for general paints A foaming agent etc. can be used.

<Solubility parameter (SP value)>
The difference in solubility parameter (SP value) between (A) fluororesin and (B) polyester resin is preferably 1.0 to 1.5.
Calculation of SP value of resin was performed as follows. Dissolve the resin in tetrahydrofuran (THF) to make a 2.5 wt% solution, aliquot a portion of the solution into VTHF, titrate with hexane (Hexane) and ion-exchanged water (Water), respectively, and become cloudy SPn and SPh were calculated by substituting VHexane and VWater of the drop amount (ml) in the following formulas (1) and (2), respectively. Next, the SP value obtained by substituting the obtained SPn and SPh into the equation (3) was obtained.
SPn = (SPTHF × VTHF + SPHexane × VHexane) / (VTHF + VHexane) (1)
SPh = (SPTHF × VTHF + SPWater × VWater) / (VTHF + VWater) (2)
SP = 10 ^ ((logSPn + logSPh) / 2) (3)
(However, SPTHF = 9.5, SPHexane = 7.2, SPWater = 23.4)

  When the difference in SP value of each resin is less than 1.0, (A) the fluororesin and (B) the polyester resin tend to become compatible when melted and cured to form a coating film, such as the upper layer / lower layer Layer separation is difficult to occur, and if the difference in SP value exceeds 1.5, there is a concern about delamination or poor appearance between the upper layer and the lower layer although layer separation occurs.

  The powder coating material of the present invention is produced by dry blending the above-mentioned pigment-containing polyester resin powder and fluororesin powder. In order to form a coating film using this powder coating material, an electrostatic coating process and a baking process are performed.

  Aluminum coating materials such as aluminum extrusion molding materials and aluminum plate materials are suitable as members (painting members) having this coating film, but can also be applied to metal materials other than aluminum, various inorganic materials, resin materials, and composite materials. It is.

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. In the examples and comparative examples, “part” and “%” are based on mass.
The following raw materials were used in the following examples and comparative examples.

<Fluorine resin>
Asahi Glass Co., Ltd., trade name Lumiflon LF710F (hydroxyl group-containing fluororesin), solubility parameter 8.58
<Polyester resin>
Polyester resin 1: Nippon Iupika Co., Ltd., trade name Iupika Coat GV570 (hydroxyl group-containing polyester resin), solubility parameter 9.99
Polyester resin 2: Nippon Iupika Co., Ltd., trade name Iupika Coat GV150 (hydroxyl group-containing polyester resin), solubility parameter 9.88
Polyester resin 3: Shinto Paint Co., Ltd. in-house synthesized product (hydroxyl group-containing polyester resin), solubility parameter 9.11.
Polyester resin 4: Shinto Paint Co., Ltd. in-house synthetic product (hydroxyl group-containing polyester resin), solubility parameter 10.25
Polyester resin 5: manufactured by Daicel Cytec Co., Ltd., trade name CRYLCOAT 4642-3 (carboxyl group-containing polyester resin), solubility parameter 9.75
<Pigment>
≪Coloring pigment≫
Titanium oxide: DuPont, trade name Ti-Pure R-706
Bengala: Toda Kogyo Co., Ltd., trade name TODA COLOR 160ED
<External pigment>
Calcium carbonate: Maruo Calcium Co., Ltd., trade name SUPER-S
<Epoxy resin>
Manufactured by Dow Chemical Co., Ltd. E. R. 662-E
<Curing agent>
Isocyanate: ε-caprolactam block isocyanate, manufactured by Evonik Degussa, trade name VESTAGON B1530
Primid: Product name Primid XL-552 manufactured by EMS

[Examples 1-20, Comparative Examples 1-10]
<Making powder paint>
For Formulation Examples F-1 to F-6 and P-1 to P-12, the raw materials shown in Tables 1 and 2 are blended as shown in Tables 1 and 2, mixed well, melt-kneaded, and finely pulverized. Thereafter, classification was performed to obtain each powder.
Then, about Examples 1-20 and Comparative Examples 1-10, each fluororesin powder and polyester resin powder are combinations shown in Tables 3 and 4, and the fluororesin powder ratio becomes the ratio shown in Tables 3-5. Each powder paint was obtained by dry blending at a ratio.

<Creation of test plate>
In the powder coating materials prepared in Examples 1 to 20 and Comparative Examples 1 to 10, an anodized aluminum plate having a thickness of 1.5 mm was suspended in the vertical direction, and a corona charging electrostatic powder coating machine (Nippon Parkerizing Co., Ltd.). GX-304 type) and electrostatically coated to a film thickness of 60 μm at a voltage of −60 KV, baked in an electric furnace under the condition of 180 ° C. × 20 minutes, melted and cured, and left at room temperature. It stood to cool until it became, and produced the test plate.
Thereafter, various evaluation tests described below were performed, and the results are shown in Tables 3 to 5.
-Appearance of coating film Visually determine the state of the coating film surface after coating plate preparation.
Gloss value According to JIS K 5600-4-7 (specular gloss), the 60 ° specular gloss is measured with a gloss meter (HG-6 manufactured by Suga Test Instruments).
・ Adhesiveness In accordance with JIS K 5600-5-6 (cross-cut method), whether or not the coating film is peeled off by peeling the tape after applying the adhesive tape after cutting the coating film at 100 squares at 1 mm intervals. evaluate.
-Weight drop resistance Based on JIS K5600-5-3 (DuPont type), the crack of a coating film is evaluated about the resistance of the coating film with respect to a drop height of 50 cm with a weight of 1/2 [phi] and a weight of 500 g.

Claims (6)

  A powder paint obtained by dry blending two or more types of resin powders having a pigment concentration (wt% value) of 5 points or more.   2. The polyester resin powder paint containing pigment and the fluororesin powder paint containing pigment are dry blended, and the pigment concentration of the fluororesin powder paint is higher than the pigment concentration of the polyester resin powder paint. Powder paint characterized by high price.   The polyester resin powder paint containing pigment and the fluororesin powder paint containing pigment are dry blended according to claim 1, wherein the pigment concentration of the polyester resin powder paint is higher than the pigment concentration of the fluororesin powder paint. Powder paint characterized by high price.   The powder coating material according to claim 2, wherein the ΔSP value of the polyester resin and the fluororesin is 1.0 to 1.5.   5. The powder concentration obtained by dry blending 60 to 80 wt% of a polyester resin powder coating and 20 to 40 wt% of a fluororesin powder coating in claim 4, wherein the pigment concentration in the polyester resin powder coating is 50 wt% or less. A powder coating material characterized in that the pigment concentration contained in the fluororesin powder coating material is 50 wt% or less.   The coating member which has a coating film formed by electrostatic coating and baking using the powder coating material of any one of Claims 1 thru | or 5.