JPWO2005073328A1 - Powder coating containing PTT - Google Patents

Abstract

The present invention provides a powder coating comprising polytrimethylene terephthalate. The powder coating material preferably has a content of a component that melts during coating of 30 to 100% by weight. With such a powder coating, it is possible to perform coating having excellent surface protection performance such as corrosion resistance and impact resistance and a beautiful appearance without a pinhole.

Description

  The present invention relates to a powder coating material containing polytrimethylene terephthalate. More specifically, a powder coating suitable for powder coating having excellent surface protection performance such as corrosion resistance and impact resistance, excellent appearance, and good coating properties, and the powder coating were used. It relates to the painting method.

  Unlike solvent coating, which has been widely used in the past, powder coating is a method of forming a coating film by melting a paint by heat without using a solvent, and therefore hardly generates volatile organic compounds. For this reason, it has many features such as not deteriorating the environment, less concern about fire, no concern about poisoning due to solvents, and the ability to reduce paint costs because paint can be reused. In recent years, the use has been greatly expanded.

  Of these, powder coatings that use thermoplastic polyester resins have features such as excellent adhesion to objects, excellent anticorrosion performance, and high coating strength, and are highly reliable anticorrosion coatings for outdoor equipment. Has attracted attention as. However, such a powder coating is difficult to become a fine powder, has a high melting point, and has a high melt viscosity. For this reason, there are problems such as difficulty in painting with an excellent appearance and poor workability at the time of coating, and its application is limited.

As a technique for solving these problems, there is a proposal of a powder coating made of polyethylene terephthalate (hereinafter abbreviated as “PET”) having a specific range of particle size, ratio of major axis to minor axis, and intrinsic viscosity (hereinafter referred to as “PET”) ( For example, see Patent Document 1). If this technique is used, it is possible to finish the painted surface relatively beautifully without eliminating the skin and bubbles. Moreover, it can be set as the coating material which has the softness | flexibility which does not generate | occur | produce a crack even if a coating material is bent, and also had the outstanding weather resistance.
However, adhesion to a metal surface and impact resistance, particularly thermal shock resistance in a cold cycle are not satisfactory levels, and improvement in the beauty of the painted surface is desired. Furthermore, since the melting point is almost the same as that of pure PET having no additive, it is necessary to melt the coating by heating it to a temperature close to 300 ° C. during coating. For this reason, there is a problem in that an object subject to thermal oxidative degradation such as a hot dip galvanized steel sheet can be applied only to a limited thing such as a thick steel sheet having a large heat capacity.

  As a technique for improving adhesion and lowering the temperature during coating, a powder coating using PET obtained by copolymerizing isophthalic acid or 1,4-butanediol has also been proposed (for example, Patent Documents 2 and 3). reference). However, since copolymerized PET is used in the technique, the hardness of the resulting coating film is reduced, and the most important characteristic is anticorrosion performance, particularly resistance to alkali components derived from cement and the like. End up. In addition, it becomes difficult to pulverize into a fine powder by lowering the glass transition point. As a result, the particle size of the paint becomes large, causing irregularities on the surface, resulting in a problem that a beautiful coating film cannot be obtained, or pinholes that greatly reduce the weather resistance are easily formed. .

  Technologies for grinding a resin with a low glass transition point into fine powder include mechanical grinding while cooling with liquid nitrogen, etc., and adding a poor solvent to a solution in which the resin is dissolved in a good solvent to precipitate the resin. Thus, a technique of so-called chemical pulverization for producing powder has also been proposed (see, for example, Patent Document 4). By using these techniques, fine pulverization is certainly possible. However, complicated equipment for using liquid nitrogen or a solvent is required, or the process time is increased, resulting in a considerably long working time, and the productivity is extremely deteriorated.

This document also proposes a technique of pulverizing coarse pellets having a crystallinity of 35% or more obtained by heat-treating a resin mainly composed of PET at 170 ° C. for 6 to 17 hours. However, according to the study by the present inventors, the crystallinity that can improve the pulverizability and the conditions for achieving such crystallinity vary depending on the resin components. Therefore, even if this technique is directly applied to a resin other than PET, the target powder cannot be obtained with high productivity. Moreover, even if this technique is used, improvement in anticorrosion performance cannot be expected.
As described above, the conventional techniques cannot maintain a smooth and beautiful coating film without pinholes while maintaining excellent surface protection performance such as adhesion, corrosion resistance, and impact resistance. Furthermore, it has not been possible to obtain a powder paint that can be produced with good productivity while keeping the temperature during coating low.
JP 50-159541 A JP-A-61-203180 JP 62-45673 A JP 2000-53892 A

  The present invention uses a powder coating that can be applied with excellent surface protection performance such as corrosion resistance and impact resistance, a beautiful appearance without pinholes, and can be manufactured with high productivity, and the powder coating. The purpose is to provide a painting method.

As a result of intensive studies, the present inventors have found that the above problems can be solved by including polytrimethylene terephthalate in the powder coating material, and have made the present invention.
That is, the aspects of the present invention are as follows.
(1) A powder coating containing polytrimethylene terephthalate.
(2) The powder coating material according to (1), wherein the content of the component that melts during coating is 30 to 100% by weight.
(3) The powder coating material according to (1) or (2), wherein the ratio of polytrimethylene terephthalate to a component that melts during coating is 30 to 100% by weight.
(4) The powder coating material according to any one of (1) to (3), wherein the average particle diameter is 1 to 500 μm.
(5) The powder coating material according to any one of (1) to (4), wherein the average particle size is 5 to 250 μm.
(6) The powder coating material according to any one of (1) to (5), which is mechanically pulverized and / or chemically pulverized.
(7) The powder coating material according to any one of (1) to (6), which is pulverized after being previously heat-treated at 60 to 230 ° C. for 1 minute or more.
(8) The powder coating material according to any one of (1) to (6), which is pulverized after heat treatment in advance at 150 to 230 ° C. for 5 minutes to 200 hours.
(9) The powder coating material according to (7) or (8), wherein the pulverization is performed by mechanical pulverization at normal temperature.
(10) In any one of (1) to (9), at least one functional substance selected from the group consisting of a photocatalyst, a deodorant and an antibacterial agent is added as separate particles from polytrimethylene terephthalate. The powder coating described.
(11) A structure in which the powder coating material according to any one of (1) to (10) is coated on a part or the entire surface of the structure.
(12) The structure according to (11), wherein the structure is one selected from the group consisting of a shopping cart, a steel pipe column, a net basket, and a fence.
(13) A coating film containing polytrimethylene terephthalate formed on the structure.
(14) The coating film according to (13), wherein a ratio of polytrimethylene terephthalate to a component that melts during coating is 30 to 100% by weight.
(15) The coating film is formed by adhering the powder coating material according to any one of (1) to (10) to a part of or the entire surface of the structure, and subsequently heating and melting the powder coating material. A method of painting, including forming.
(16) A coating method comprising: bringing the powder coating material according to any one of (1) to (10) into contact with a heated structure to melt the powder coating material to form a coating film.
(17) The method according to (16), comprising heating again after forming the coating film.
(18) The method according to any one of (15) to (17), comprising cooling the heated powder coating material and the structure in a gas.
(19) The method according to any one of (15) to (17), comprising quenching a heated powder coating material and an object to be coated in a liquid.

  The powder coating of the present invention is suitable for various applications including outdoor equipment that requires highly reliable anti-corrosion coating, shopping carts and baskets that require good appearance and impact resistance. It becomes possible to perform powder coating. Further, since the powder coating material is obtained by mechanical pulverization without using a special chemical such as liquid nitrogen, it can be manufactured with high productivity and low cost without using complicated equipment.

The present invention will be specifically described below. First, the powder coating material of the present invention will be described.
The powder coating of the present invention needs to contain polytrimethylene terephthalate (hereinafter sometimes abbreviated as PTT). Surprisingly, when the powder coating material contains PTT, an excellent feature not present in the conventional powder coating material is exhibited. As a characteristic of the powder coating material of the present invention, firstly, the impact resistance, adhesion, corrosion resistance, and weather resistance of the obtained coating film are increased. This is expected to be derived from the chemical stability resulting from the molecular structure of PTT and the impact absorption resulting from the molecular skeleton structure of zigzag. Secondly, lowering the coating temperature and shortening the time can be mentioned. This is probably because PTT has a lower melting point than PET, which is a general polyester. Thirdly, improvement in grindability is mentioned. This is particularly noticeable when the PTT is heat-treated at a high temperature, but it seems that the PTT is easily crystallized and easily cracks when it is deformed beyond a certain level by crystallization. As a result, the pulverization ability can be increased in the mechanical pulverization and the pulverization is facilitated. When the coating material is pulverized, the coating film can be made smoother and thinner, the coating temperature can be lowered, and the coating operation can be shortened.

Here, PTT is a polyester having terephthalic acid as an acid component and trimethylene glycol (also referred to as 1,3-propanediol, hereinafter abbreviated as “TMG”) as a diol component. The PTT includes a case where 0 to 50% by weight of other components are copolymerized as long as the effects of the present invention are not impaired. Examples of such copolymer components include 5-sodium sulfoisophthalic acid, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentamethylene glycol, 1,6-hexamethylene glycol, Heptamethylene glycol, octamethylene glycol, decamethylene glycol, dodecamethylene glycol, 1,4-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, oxalic acid, malon Acid, succinic acid, glutaric acid, adipic acid, heptanedioic acid, octanedioic acid, sebacic acid, dodecanedioic acid, 2-methylglutaric acid, 2-methyladipic acid, fumaric acid, maleic acid, itaconic acid, 1,4 -Cyclohexanedicarboxylic acid, 1 3-cyclohexane dicarboxylic acid, ester-forming monomers or polyethylene glycol such as 1,2-cyclohexanedicarboxylic acid, polypropylene glycol, polytetramethylene glycol and copolymers thereof, and the like. The other copolymer component is preferably 30% by weight or less, and more preferably 20% by weight or less in consideration of the performance and pulverizability of the coating film.
Further, the term “containing PTT” means that the same chemical as the PTT homopolymer is obtained by analysis using ¹ H nuclear magnetic resonance spectrum (hereinafter abbreviated as “NMR”) using HFIP: CDCl ₃ = 1: 1 as a solvent. It means that a spectrum is observed at the position of the shift.

  The powder paint of the present invention preferably contains 10 to 100% by weight of PTT as described above. Since the powder coating material is composed of a component that melts at the time of coating and a component that does not melt, the preferred amount of PTT varies depending on these ratios. Here, the component that melts at the time of coating is the most preferable upper limit value of the heating temperature in the powder coating method of the present invention described later, and is the most in electrostatic coating that is the coating method performed at the lowest temperature. It indicates a component that melts at a temperature of 280 ° C. or lower, which is the upper limit of the preferred temperature range. By setting the PTT weight ratio in the powder coating to the above-described range, it becomes easy to simultaneously satisfy the excellent surface protection performance, the beautiful appearance, and the ease of manufacture which are the objects of the present invention. The PTT is more preferably 20 to 100% by weight, and particularly preferably 40 to 100% by weight. When the coating film is required to have flexibility, the PTT ratio is desirably 70 to 100% by weight. The weight ratio of PTT can be determined by NMR.

  The content of the component that melts during coating varies depending on the purpose and conditions of the coating. In addition, although it is difficult to measure the amount of components to be melted in powder paint, the type and amount of substances contained are estimated by analyzing the composition, and the total amount of components to be melted is calculated. When the amount of the component to be melted can be determined, it is preferably 30 to 100% by weight of the powder coating material in order to increase the impact resistance, smoothness and gloss of the coating film, and 50 to 100% by weight. % Is more preferable, and 70 to 100% by weight is particularly preferable. The ratio of the PTT to the melting component is preferably 30 to 100% by weight, more preferably 50 to 100% by weight, and particularly preferably 70 to 100% by weight.

  Examples of the melting component other than PTT contained in the powder coating of the present invention include resins other than PTT, cyclic and linear oligomers, monomers of acid components and glycol components constituting PTT, and various additives. . Examples of resins other than PTT include polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyamides such as nylon 6, nylon 66, nylon 11, and nylon 12, polyolefins such as polyethylene and polypropylene, polyurethanes, fluoropolymers, and polyphenylenes. Examples thereof include sulfite and copolymer resins thereof. It is also a preferable example that such a resin is obtained by once collecting a product formed into a fiber, a film, a bottle or the like.

  On the other hand, the non-melting component contained in the powder coating of the present invention includes high melting point or non-melting polyester, polyolefin, polyamide, epoxy, acrylic, cellulose and other resins, organic and inorganic pigments, glass fibers, carbon fibers, Additives such as talc, mica, wollastonite, kaolin clay, calcium carbonate, titanium dioxide and other inorganic fillers, silica dioxide and other surface conditioners and stabilizers for controlling gloss and smoothness, and polymerization A catalyst residue etc. are mentioned.

  Further, in the present invention, various additives such as a matting agent, a heat stabilizer, a flame retardant, an antistatic agent, an antifoaming agent, a color stabilizer, an antioxidant, an ultraviolet absorber, and a crystal nucleating agent are used as necessary. , Including brighteners, impurity scavengers, surface conditioners and the like.

  In particular, in the present invention, a stabilizer is preferably added, and pentavalent and / or trivalent phosphorus compounds and hindered phenol compounds are preferred. The addition amount of the phosphorus compound is preferably 2 to 500 ppm, more preferably 10 to 200 ppm as the weight ratio of the phosphorus element in the powder coating material. Specific examples of the preferred compound include trimethyl phosphite, phosphoric acid, phosphorous acid, and tris (2,4-di-tert-butylphenyl) phosphite (such as Irgafos 168 manufactured by Ciba Specialty Chemicals). .

  The hindered phenol compound is a phenol derivative having a substituent having a steric hindrance at a position adjacent to a phenolic hydroxyl group, and a compound having one or more ester bonds in the molecule. The addition amount of the hindered phenol compound is preferably 0.001 to 1% by weight, more preferably 0.01 to 0.2% by weight as a weight ratio with respect to the powder coating material. Specific examples of the compound include pentaerythritol-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] (such as Irganox 1010 manufactured by Ciba Specialty Chemicals), 1, 1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate (Ciba Specialty) Chemicals Co., Ltd. Irganox 1076), N, N′-hexamethylenebis (3,5-tert-butyl-4-hydroxy-hydrocinnamamide), ethylenebis (oxyethylene) bis [3- (5- tert-butyl-4-hydroxy-m-tolyl) propionate] -Irganox 245 manufactured by Specialty Chemicals Co., Ltd.), N, N'-hexane-1,6-diylbis [3- (3,5 di-tert-butyl-4-hydroxyphenylpropionamide)] (Ciba Specialty chemicals, Inc., Irganox 1098, etc.) are preferred. Of course, using these stabilizers in combination is one of the preferred methods.

  In the present invention, it is also one of preferable methods to add a scavenger for low molecular weight volatile impurities. The scavenger is preferably a polyamide or polyesteramide polymer or oligomer, or a low molecular weight compound having an amide group or an amine group. Specifically, polyamides such as nylon 6.6, nylon 6, nylon 4.6, and polymers such as polyethyleneimine, and the reaction product of N-phenylbenzeneamine and 2,4,4-trimethylpentene (Ciba Irganox 5057 manufactured by Specialty Chemicals Co., Ltd.), N, N′-hexane-1,6-diylbis [3- (3,5 di-tert-butyl-4-hydroxyphenylpropionamide)] (Ciba Irganox 1098 manufactured by Specialty Chemicals Co., Ltd.), 2,6-di-tert-butyl-4- (4,6-bis (octylthio) -1,3,5-triazin-2-ylamino) phenol (Ciba)・ Irganox 565 manufactured by Specialty Chemicals Co., Ltd.) is preferable. Of course, a combination of these is also one of the preferred methods.

  Further, in the case of applications mainly used outdoors, it is preferable to add an ultraviolet absorber. As the ultraviolet absorber, benzotriazole or triazine is preferable. Specifically, 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5-[(hexyl) oxy] -phenol (TINUVIN 1577FF manufactured by Ciba Specialty Chemicals Co., Ltd.) And 2- (2H-benzotriazol-2-yl) -p-cresol (such as TINUVIN 234 manufactured by Ciba Specialty Chemicals Co., Ltd.) and the like are preferable. Of course, a combination of these is also one of the preferred methods.

  In this invention, the case where these components are reacting with PTT and the case where it mixes simply are included. Moreover, the case where one particle | grain is formed with PTT also includes the case where it mixes as a separate particle | grain and forms the powder coating material.

  Representative examples of components added as separate particles from PTT include, but are not limited to, lubricants, pigments, surface conditioners, and the like for suppressing blocking and improving the handleability of powders. . As the lubricant, silica having an average particle diameter of 1 μm or less is preferable. Moreover, it can also be set as a metallic-tone coating film by adding mica etc. as a particle separate from PTT.

  Moreover, in this invention, it is also an example of a preferable method to mix functional substances, such as a photocatalyst, a deodorizing agent, and an antibacterial agent, which add a new function to the obtained coating film. These substances can be selected as appropriate depending on their characteristics when mixing as a single particle with PTT and when mixing as separate particles.

The powder coating of the present invention usually has an average particle size (average particle size of all particles contained in the powder coating including components other than PTT and PTT) of 1 to 500 μm. It is preferable that it is 5-250 micrometers. When the average particle size is 1 μm or more, handling of the powder by transfer or painting becomes easy. In addition, by making it 500 μm or less, it becomes easy to obtain a smooth and beautiful coating film which is one of the objects of the present invention, and even if the coating film thickness is reduced, it becomes difficult to make pinholes, It is possible to lower the temperature during painting. The average particle size is more preferably from 10 to 200 μm, further preferably from 15 to 150 μm, particularly preferably from 20 to 100 μm. Moreover, in order to obtain a beautiful coating film and to make it easy to handle, it is preferable that particles having a particle size of 1 to 500 μm are 95% by weight or more of the total particles contained in the powder coating material.
In addition, the shape of the particles is preferably a shape close to a sphere or a cube, with few whiskers and film-like projections, so that the particles are not easily aggregated by a pipe or the like and can be easily transferred and easily applied uniformly to the coating surface. .

The powder coating material of the present invention preferably starts to melt at a temperature of 150 to 240 ° C. and can form a coating film. The term “melting” here means that independent particles are combined and united and are not easily separated as individual particles. The preferable melting temperature varies depending on the application, but it is more preferable that the melting temperature starts at 180 to 230 ° C. in a normal metal paint. By doing in this way, it becomes easy to make the heat resistance of a coating film and the ease of coating compatible.
Further, the viscosity at the time of melting of the powder paint of the present invention is preferably 0.1 to 5000 Pa · s at 260 ° C., more preferably 0.5 to 1000 Pa · s, and 1 to 500 Pa · s. More preferably. It becomes easy to obtain a smooth coating film by setting it as this range.

Next, the coating film obtained by this invention is demonstrated.
The coating film obtained by the present invention is a coating film containing PTT formed on a solid structure.
Examples of the solid structure include metals, resins, ceramics, stones, ceramics, porcelain, wood, and paper. Among these, metals such as steel materials mainly composed of iron elements, stainless steel, and steel materials plated with zinc or chromium are preferable because a good coating film can be easily formed.

  Since the composition of the coating film is a powder coating having almost no volatile component, it consists of almost the same components as those described above or components obtained by reacting these components with heat or the like. The average thickness of the coating film is preferably 5 to 2000 μm. By making it in this range, it becomes easy to achieve both excellent surface protection performance and excellent appearance. When emphasizing the surface protection performance, the thickness is more preferably 50 μm or more, still more preferably 100 μm or more, and particularly preferably 200 μm or more. In the case where the appearance is important, the thickness is more preferably 500 μm or less, further preferably 300 μm or less, and particularly preferably 200 μm or less. The coating film having such a thickness is preferably free from pinholes in order to improve the anticorrosion performance.

When the coating film is formed on a metal, it is preferably 20 kg / cm ² or more, more preferably 30 kg / cm ² or more, more preferably 40 kg / cm ² or more according to a test method according to JIS K 5400. Is more preferable, and 50 kg / cm ² or more is particularly preferable.
The impact resistance of the coating film is the maximum height at which a coating film is not defective when a hemispherical steel ball with a mass of 300 g and a tip radius of 12.7 mm is dropped by a test method according to JIS K 5400. It is preferably 30 cm or more, more preferably 50 cm or more, and particularly preferably 70 cm or more. Further, the hardness of the coating film is preferably 4B or more, more preferably 2B or more, and still more preferably F or more, in accordance with JIS K5400 in terms of pencil hardness by hand-drawing method.

Next, the manufacturing method of the powder coating material of this invention is demonstrated.
For the production of the powder coating material of the present invention, a composition containing PTT obtained by polymerization; or a composition containing PTT obtained by polymerization is cooled and solidified, or in a molten state, uniaxially or biaxially. A composition containing PTT, which is put into a shaft extruder or the like and melt-kneaded with additives such as pigments and stabilizers, is used. Then, the composition can be produced by pulverizing using a known mechanical pulverizer after forming the solid composition such as pellets obtained by extruding the composition into water in the form of strands and cooling, solidifying and cutting.

  Polymerization of an acid component and a diol component for obtaining a composition containing PTT can be performed by a conventionally known method. For example, dimethyl terephthalate and trimethylene glycol, and if necessary, other copolymer components were used as raw materials, and transesterification was performed at a normal pressure and a temperature of 180 to 260 ° C. using titanium tetrabutoxide as a catalyst by a conventional method. Thereafter, a polycondensation reaction is performed at 220 to 270 ° C. under reduced pressure.

  The intrinsic viscosity [η] of the composition containing PTT is preferably 0.3 to 3.0 dl / g. The strength of the coating film obtained by increasing the degree of polymerization so that the intrinsic viscosity [η] is 0.3 dl / g or more can be increased. Moreover, it becomes easy to obtain a smooth coating film surface by not increasing the degree of polymerization so that the intrinsic viscosity [η] is 2.0 dl / g or less. The intrinsic viscosity is more preferably 0.35 to 2.5 dl / g, and particularly preferably 0.4 to 2.0 dl / g. Further, the carboxyl group concentration at the end of the PTT is preferably 0 to 100 eq / ton, more preferably 0 to 80 eq / ton, particularly preferably 0 to 50 eq / ton in order to increase the weather resistance of the resulting coating film. . In order to further improve the weather resistance, the content of the dipropylene glycol component (hereinafter abbreviated as “DPG”), which is a trimerene glycol dimer, is preferably 0 to 2% by weight, It is more preferable that it is weight%, and it is especially preferable that it is 0 to 1.2 weight%.

  As a method of adding additives necessary for making a powder coating, a method of adding at the time of polymerization, a method of adding at the time of melt kneading after polymerization, a method of adding as independent particles, or a combination of these two or more A method is mentioned. From these methods, it can be appropriately selected depending on the kind and amount of additives, required performance, and the like.

  In the present invention, the solid matter containing PTT can be pulverized by either mechanical pulverization or chemical pulverization. Since a special solvent and equipment are not required and productivity is good, a method in which heat treatment is performed at a temperature of 60 ° C. or more for 1 minute or more and then mechanical pulverization is performed at a temperature near room temperature is most preferable. It is desirable that the temperature of the heat treatment be equal to or lower than the temperature at which the solid matter is fused. The heat treatment time may be long, but in practice it is preferably 300 hours or less. Here, the vicinity of normal temperature means a case where equipment for controlling the temperature of the pulverizer is not provided, and a case where equipment or solid matter is cooled using cold air or a refrigerant of −40 to 20 ° C. It is not included in the case of so-called freeze pulverization, in which the material is immersed in a refrigerant or the like. In such mechanical pulverization, the temperature of the pulverizer rises due to frictional heat, but is preferably 150 ° C. or lower, more preferably 120 ° C. or lower, and still more preferably 100 ° C. or lower. As described at the beginning, unlike PET and nylon, which are generally used, it is possible to pulverize with good productivity by mechanical pulverization at room temperature as described above because of the use of PTT, which is one of the features of the present invention. It is.

  There is no restriction | limiting in particular as an equipment which grind | pulverizes, A well-known grinder can be used. For example, impact type fine grinding machines such as Hosokawa Micron Co., Ltd. ACM Pulperizer, Turbo Industry Co., Ltd. turbo mill, Nisshin Engineering Co., Ltd. blade mill, and Seisin Enterprise Co., Ltd. jet mill etc. Machine. In the present invention, an impact-type pulverizer is preferable because the productivity is higher than the characteristics of PTT.

  The heat treatment of solids such as pellets is preferably performed at a temperature of 60 ° C. or higher for 1 minute or longer, but in order to further improve the grindability, it is more preferably performed at a temperature of 150 ° C. to 230 ° C. for 5 minutes to 200 hours. preferable. By such heat treatment, the crystallinity of PTT contained in the solid can be increased, and it becomes easy to obtain a fine powder at a high yield, and it is also easy to reduce the whiskers of the powder particles. become. The temperature of the heat treatment is more preferably 180 to 225 ° C, particularly preferably 200 to 220 ° C. The heat treatment time is more preferably 10 minutes to 100 hours, further preferably 15 minutes to 50 hours. The heat treatment is preferably performed in an inert gas atmosphere such as nitrogen or carbon dioxide gas in order to suppress coloring of PTT by oxygen.

  It is preferable that the pulverized solid is subsequently classified and filtered. Coarse particles and fine particles are removed by classification and filtration, thereby making it easier to obtain a smooth coating film and handling of the powder coating material. Such classification and filtration can be performed using a vibration sieve or an air classifier.

  The powder thus obtained can be further mixed with other powder using a Henschel mixer or the like. In the present invention, all of the pigments and various additives and the powder containing PTT are mixed in this mixing step by a dry method, or when the powder containing PTT containing different additives is mixed. This includes any case where powders containing PTT of different colors are mixed to form a new color paint. In mixing the powder, it is preferable to appropriately adjust the size of the powder in accordance with the specific gravity difference or amount. In particular, when mixing particles having different colors, it is desirable to use powders with smaller particle diameters in order to obtain a uniform and beautiful coating film.

Finally, the painting method will be described.
In the present invention, it can be applied to a wide variety of substances such as metals, resins, ceramics, stones, ceramics, porcelain, wood, paper and the like. Among these, metals, particularly steel materials mainly composed of iron elements, plated products thereof, stainless steel, and the like are preferable because a good coating film can be easily formed.

  As a coating method, a so-called “electrostatic coating method” in which a coating film is formed by adhering a paint to the surface of an object to be coated by static electricity or the like, and then melting and adhering the powder paint by heating from the outside. Can be used. In addition, the powder coating material of the present invention is lifted by a gas flow, and the coating material is formed by immersing the pre-heated article in a layer that is in a fluid state to form a coating film. The so-called “fluid dipping method” can also be used. In the fluid immersion method, in order to obtain an excellent coating film, the coating film may be adhered and then heated again from the outside to smooth the coating film. In addition to the above-described coating method, the present invention includes a case where the coating is performed by a so-called “thermal spraying method” in which the coating is softened by passing through a high-temperature flame at high speed and the softened coating is fused to an object to be coated. . Since this method does not require a furnace, it has the feature that it can be constructed on site.

  In the electrostatic coating method, the temperature and time of heating from the outside vary depending on the size and shape of the object to be coated, the thickness of the coating film, the required smoothness of the coating film, and the like. 230-350 degreeC and 0.5-30 minutes are respectively preferable, 235-300 degreeC and 0.7-20 minutes are more preferable, 240-280 degreeC and 1-10 minutes are still more preferable. On the other hand, the temperature at which the article to be coated is preliminarily heated in the fluidized immersion method is preferably 230 to 400 ° C, more preferably 240 to 380 ° C, still more preferably 250 to 350 ° C, and particularly preferably 280 to 320 ° C. In the case of the fluid dipping method, it may be long as long as the article to be coated does not deteriorate. In any method, it is easy to obtain a tough and beautiful coating film without deteriorating the paint by setting the temperature to such a temperature.

  In the present invention, the paint melted after adhering to the object to be coated by the above-described method is cooled by being brought into contact with a coolant such as water, so-called "rapid cooling", and slowly cooled in the air as it is. There is a case of so-called “slow cooling”. Rapid cooling is preferred when it is desired to increase the gloss of the coating film or toughness, and slow cooling is preferred when it is desired to increase the hardness of the coating film surface or suppress the gloss. When cooling by contacting with a coolant, it is preferable to circulate the coolant to prevent bubbles from being generated on the surface of the coating film and resulting in poor appearance.

  It is preferable that the particle size and composition of the paint used for coating are appropriately selected according to the coating method, the target thickness and surface smoothness, and other required performance. In general, a coating material having an average particle size of 50 to 150 μm is preferable in the fluid immersion method, and a coating material having an average particle size of 20 to 80 μm is preferable in the electrostatic coating method.

  In the present invention, pretreatment of the surface of the object to be coated is not particularly necessary, but pretreatment is preferably performed in order to increase the adhesion strength or form a beautiful coating film. Examples of such pretreatment include degreasing treatment and acid treatment for removing fats and oils adhering to the surface, and blasting treatment for removing the rust on the surface and roughening the surface for the anchoring effect. However, primer treatment for applying an epoxy resin or the like widely used for powder coating of nylon or polyethylene is not essential, and this is one of the features of the present invention.

  The coating with the powder coating of the present invention is mainly made of face materials such as a combination of pipes and wire rods and flat plates such as shopping carts, carts, refrigerators, etc., and outer plates of electric products such as lockers and refrigerators. It can be applied to various structures such as combinations, guardrails, fences, various pipes for transporting liquids and gases, and steel pipe columns. Among these, it is particularly suitable for shopping carts and carts that make use of the surface protection performance such as impact resistance and anticorrosion and the beauty of the exterior, and steel pipe columns that make use of the excellent anticorrosion performance.

(Example)
The present invention will be described based on examples.
The main measurement values in the examples were measured by the following methods.
(1) PTT content rate and DPG content rate PTT content rate and DPG content rate (% by weight) are obtained by dissolving 100 mg of paint or coating film in a solvent (HFIP: CDCl ₃ = 1: 1) and removing insoluble components by MEMBRANE FILTER ( 1 [mu] m, using a solution after filtration through a ^PTFE), determined by 1 H-NMR. As a measuring machine, FT-NMR DPX-400 (manufactured by Bruker) was used. The insoluble component removed by filtration was used for measuring the weight after vacuum drying and obtaining the PTT content and the DPG content. In addition, the DPG content is simply described as “DPG” in Table 1 described later.

(2) Particle size (average particle size, particle size distribution)
The particle size (average particle size, particle size distribution) of the powder dispersed in water was measured using a Microtrac FRA particle size analyzer manufactured by Nikkiso Co., Ltd. using a laser light diffraction / scattering method. The particle size distribution was determined as the weight percent of particles having a particle size of 1 to 500 μm (described as “main ratio” in Table 1 described later).

(3) Shape The shape of the powder particles was observed with an optical microscope. Regarding the evaluation of the presence or absence of whiskers in the powder, “○” indicates that almost no whiskers are observed, “△” indicates that whiskers are frequently observed, and “×” indicates that many beards are observed. did.
(4) Fluidity A cylindrical shape with a diameter of 200 mm, and a 2 kg powder coating material is placed in a fluidized immersion layer in which PE nonwoven fabric is stretched from the bottom so that air flows uniformly in the cross section. The fluidity when air was introduced so as to be 1.4 times was visually judged. The case where the whole was uniformly floated when air was introduced was marked with “◯”, the case where local powder was frequently blown out was marked with “X”, and the middle was marked with “Δ”.

(5) Melting start temperature The powder coating material sandwiched between glass plates was placed on a hot stage having a temperature control function, and the temperature at which melting started when the temperature was raised from room temperature at 10 ° C./min was visually determined.
(6) Melt viscosity Measured at 260 ° C. and a shear rate of 100 s-1 using RMS-800 manufactured by Rheometric Co., Ltd.

(7) Film thickness Measured using an electromagnetic film thickness meter.
(8) Presence / absence of pinholes Measured using a low frequency high voltage pulse discharge type pinhole detector. The case where there was no pinhole was indicated as “◯”, and the case where there was a pinhole was indicated as “x”.

(9) Adhesiveness of coating film According to JIS K5400, an adhesive having a diameter of 20 mm was adhered to the coating film, a load was applied to the adhesive by an autograph, and a vertical force (adhesive force) for peeling was measured.
(10) Impact resistance When a hemispherical steel ball with a tip radius of 12.7 mm and a mass of 300 g is dropped by a test method according to JIS K5400, cracks, peeling, and through-holes are generated in the coating film. The maximum height at which no defects occurred was measured.

(11) Pencil hardness It measured by the hand-drawing method according to JIS K5400.
(12) Appearance The presence / absence of gloss, surface waviness and unevenness was visually determined.
Regarding the gloss, “Good” indicates “good”, “Good” indicates medium, and “No” indicates poor. In addition, regarding surface undulations and unevenness, “◯” indicates that they were hardly observed, “Δ” indicates that they were observed to some extent, and “X” indicates that they were observed in large quantities.

(13) Intrinsic viscosity (intrinsic viscosity) [η]
The intrinsic viscosity [η] is extrapolated to a zero concentration by using the Ostwald viscometer, and the ratio ηsp / C of the specific viscosity ηsp and the concentration C (g / 100 ml) in o-chlorophenol at 35 ° C. Sought according to.
[Η] = lim (ηsp / C)
C → 0
(14) Carboxyl end group concentration 1 g of the PTT composition was dissolved in 25 ml of benzyl alcohol, and then 25 ml of chloroform was added, followed by titration with a 1 / 50N potassium hydroxide benzyl alcohol solution, and the titration value V _A (ml) From the blank value V0 in the absence of the PTT composition, the following formula was used. (The carboxyl end group concentration was described as COOH in Table 1 described later.)
Carboxyl end group concentration (eq / ton) = (V _A −V ₀ ) × 20

[Example 1]
To 100 parts by weight of PTT having an intrinsic viscosity [η] of 0.9 dl / g, a carboxyl end group concentration of 15 eq / ton, and a DPG content of 1% by weight, liquid paraffin and smoil P-260 manufactured by Matsumura Oil Research Co., Ltd. 0.03% by weight as an additive, 0.1% by weight of Mitsubishi Carbon Black manufactured by Mitsubishi Chemical Co., Ltd. as a black pigment, and Irganox 1098 manufactured by Ciba Specialty Chemicals Co., Ltd. as a heat stabilizer. 0.1 parts by weight of TINUVIN234 manufactured by Ciba Specialty Chemicals Co., Ltd. as an ultraviolet absorber was dry blended and then charged into a twin screw extruder (Toshiba Machine Co., Ltd .: TEM58). Screw rotation speed 300 rpm, cylinder temperature 240 ° C. (the polymer temperature near the tip nozzle was 260 ° C.), extrusion rate 1 0 kg / hr (residence time of 1 minute), were melt-kneaded at a reduced pressure of 0.04 MPa. The kneaded polymer was made into a strand shape and extruded into water, and then cooled, solidified, and cut to obtain solid pellets.

The obtained pellets were heat-treated at 210 ° C. for 300 minutes using a tumbler dryer having an internal volume of 300 liters while flowing 10 liters / hour of nitrogen to obtain crystallized pellets.
The crystallized pellets are pulverized and classified by combining a mechanical pulverizer manufactured by Turbo Industry Co., Ltd., turbo mill (abbreviation: TM in Table 1) and a 100-mesh vibratory sieve to obtain a powder coating product. It was. Here, the pellets pulverized by a pulverizer were classified by a 100-mesh vibrating screen, and those that passed through the sieve were used as products, and those that did not pass were returned to the pulverizer and pulverized again.
Table 1 shows the main production conditions and powder paint properties.

The PTT content in the paint was 99% or more, the average particle size was as fine as 70 μm, and there was no whisker and the powder was excellent in fluidity. Further, it was a powder coating material having excellent handling properties and coating properties, with a melting start temperature of 225 ° C. and a melt viscosity of 100 Pa · s.
Next, the obtained powder coating is cylindrical with a diameter of 200 mm, and a non-woven fabric made of PE is stretched from the bottom so that air flows uniformly in the cross section. Air was introduced so that the volume was 1.4 times to create a fluidized immersion layer. A steel plate having a thickness of 3.2 mm, a length of 100 mm, and a width of 40 mm heated to 310 ° C. was immersed in this fluid immersion layer for 2 seconds to melt and adhere the paint, and then taken out and left in the air for 30 seconds. After that, it was put in water and rapidly cooled for painting. The surface of the object to be coated was blasted to give unevenness. The obtained coating film properties are shown in Table 2.
By using the powder coating obtained above, a coating film having no pinholes and having excellent adhesion, impact resistance, hardness and excellent appearance was obtained.

[Examples 2 to 5]
A powder coating was obtained in the same manner as in Example 1 except that the conditions described in Table 1 were changed. The results are shown in Table 1.
In Example 2, when the pellet was heat-treated at 80 ° C. for 30 minutes, an average particle size was increased, and although some whisker was observed in the powder particles, a powder coating without problems was obtained.
In Examples 3 and 4, when the polymerization degree of PTT was changed, although the average particle diameter of the obtained powder was different, a good powder was obtained. When coating was performed under the conditions shown in Table 2 using the paint obtained in Example 3, a good coating film having a thin film thickness at a lower temperature could be obtained. The coating material obtained in Example 4 was used for coating with cooling as air cooling. The obtained coating film had a slightly matte texture, but had excellent physical properties.
In Example 5, when heat treatment was performed at 80 ° C. for 30 minutes and the filter mesh was increased to 50 mesh, a usable powder coating material was obtained although the particle size was large and the fluidity was slightly deteriorated. When coating was performed using the obtained powder coating so as to increase the film thickness under the conditions shown in Table 2, a coating film having excellent characteristics was obtained, although some waviness and unevenness were observed. It was.

[Examples 6 to 9]
Instead of 100 parts by weight of PTT, in Example 6, 90 parts by weight of PTT used in Example 1, 10 parts by weight of PET having an intrinsic viscosity [η] of 0.6 dl / g and a carboxyl end group concentration of 40 eq / ton, were used in Example 7. In Example 8, 60 parts by weight of PTT and 40 parts by weight of PET used in Example 6 were used. In Example 8, 90 parts by weight of PTT used in Example 1, intrinsic viscosity [η] was 0.7 dl / g, carboxyl terminal. In Example 9, 10 parts by weight of PET recovered from a PET bottle having a base concentration of 50 eq / ton, 90 parts by weight of PTT used in Example 1, 0.9 dl / g of intrinsic viscosity, and 60 eq of carboxyl end group concentration were used. A powder coating material was obtained in the same manner as in Example 1 except that 10 parts by weight of PBT (polybutylene terephthalate) was used except for the conditions shown in Table 1. The results are shown in Table 1. In any case, the obtained powder coating was a powder having a fine particle size, no whiskers, and good fluidity. Moreover, the melting start temperature was as low as 210 to 220 ° C., and the melt viscosity was 100 to 500 Pa · s, which was a powder coating material excellent in handling property and coating property.
Next, coating was performed in the same manner as in Example 1 except for the conditions shown in Table 2 using the powder paint obtained in Example 6, and there was no pinhole even under a slightly low heating temperature. A coating film having excellent adhesion, impact resistance, hardness and excellent appearance was obtained. The results are shown in Table 2.

[Example 10]
Other than the conditions shown in Table 1, copolymer PTT (co-PTT) having an intrinsic viscosity of 0.9 dl / g copolymerized with 10% by weight of neopentyl glycol and a carboxyl end group concentration of 20 eq / ton is used instead of PTT. Obtained a powder paint in the same manner as in Example 1. The results are shown in Table 1. The obtained powder coating was a powder having a fine particle size and good fluidity, although some whiskers were observed. Moreover, the melting start temperature was as low as 220 ° C., and the melt viscosity was 100 Pa · s, which was a powder coating material excellent in handling property and coating property.
Next, coating was performed in the same manner as in Example 1 except for the conditions shown in Table 2 using the obtained powder coating material. There was no pinhole even under a slightly low heating temperature, and excellent adhesion and resistance. A coating film having impact properties, hardness and excellent appearance was obtained.

[Examples 11 to 13]
Instead of carbon black as a pigment, 0.1 part by weight of Macrol Red EG manufactured by Bayer Co., Ltd. is used as a red pigment in Example 11, and no pigment is used in Example 12, and white pigment is prepared in Example 13 as a white pigment. A powder coating was obtained in the same manner as in Example 1 except that 30 parts by weight of processed titanium I-131E manufactured by Kakko Co., Ltd. was used, except for the conditions shown in Table 1. The results are shown in Table 1. In any case, the obtained powder coating was a powder having a fine particle size, no whiskers, and good fluidity. Moreover, it was a powder coating material having a low melting start temperature and an excellent melt viscosity and excellent handleability and coating property.

[Example 14]
2 parts by weight of HIMILAN-1707 manufactured by Mitsui DuPont Polychemical Co., Ltd., which is an ionomer, was added as a crystal nucleating agent, and a powder coating material was obtained in the same manner as in Example 1 except for the conditions shown in Table 1. The results are shown in Table 1. The obtained powder coating material was a powder having a fine particle size, no whiskers, and good fluidity. Moreover, it was a powder coating material having a low melting start temperature and an excellent handling property and coating property with an appropriate melt viscosity.
Next, coating was performed in the same manner as in Example 1 except for the conditions shown in Table 2 using the obtained powder coating material. There was no pinhole, excellent adhesion, impact resistance, hardness, A coating film having an excellent appearance with a matte appearance was obtained.

[Example 15]
To the powder coating material obtained in Example 1, 10 parts by weight of powder of mask melon type photocatalyst (standard type, average particle size 15 μm, containing titanium dioxide 85% or more) manufactured by Taihei Chemical Industry Co., Ltd. was added. Then, it was thoroughly mixed using a Henschel mixer to obtain a new powder coating material that can be expected to have a photocatalytic function. The paint properties are shown in Table 1. The obtained powder coating material was a powder having a fine particle size, no whiskers, and good fluidity. Moreover, it was a powder coating material having a low melting start temperature and an excellent handling property and coating property with an appropriate melt viscosity.

[Example 16]
A powder coating material that can be expected to have antibacterial properties was obtained in the same manner as in Example 14 except that 1 part by weight of an antibacterial agent manufactured by Toagosei Co., Ltd. and Novalon AGZ330 was added instead of the crystal nucleating agent. The results are shown in Table 1. The obtained powder coating material was a powder having a fine particle size, no whiskers, and good fluidity. Moreover, it was a powder coating material having a low melting start temperature and an excellent handling property and coating property with an appropriate melt viscosity.

[Comparative Examples 1 and 2]
Instead of PTT, 100 parts by weight of PET used in Example 6 was used in Comparative Example 1, and 90 parts by weight of PET used in Example 6 and 10 parts by weight of PBT used in Example 9 were used in Comparative Example 2, respectively. A powder paint was obtained in the same manner as in Example 1 except for the conditions shown in FIG. As shown in Table 1, in any case, after about 10 to 30 minutes from the start of pulverization, the eyes of the vibrating screen were clogged, and the powder coating material could not be produced continuously. Examination of the powder coating obtained until the eyes were clogged revealed that in all cases the particle size was large and the powder was full of beard-like protrusions, and the fluidity was poor and could not be used for fluid immersion coating. Met.

[Example 17]
Coating was performed in the same manner as in Example 1 except that the powder coating material obtained in Example 1 was melted and adhered and then placed in an electric furnace with an atmospheric temperature of 280 ° C. and post-heated for 2 minutes. went. The obtained coating film properties are shown in Table 2. A coating film having a surface smoothness superior to that of Example 1 was obtained.

[Example 18]
250 kg of the powder coating material obtained in Example 1 was placed in a rectangular parallelepiped container having a length of 500 mm and a width of 1000 mm, and heated to 320 ° C. in a fluidized immersion layer into which air was introduced so that the volume became 1.4 times. A steel pipe having an outer diameter of 200 mmφ and a wall thickness of 2 mm was immersed for 3 seconds to melt and adhere the paint, and then taken out, left in the air for 30 seconds, and then rapidly cooled in water. The surface of the object to be coated was blasted to give unevenness.
The obtained coating film properties are shown in Table 2. There was no pinhole, and a painted product with an excellent appearance could be obtained.

[Examples 19 and 20]
In Example 19, a wire mesh formed by combining steel wires having a diameter of 3 mmφ in Example 19, and in Example 20, a steel wire having a diameter of 2 mmφ and a diameter of 3 mmφ, and a steel pipe having an outer shape of 15 mmφ and a wall thickness of 2.3 mm are combined. Coating was performed in the same manner as in Example 18 except that the conditions shown in Table 2 were used. The surface of the object to be coated was blasted to give unevenness.
The obtained coating film properties are shown in Table 2. There was no pinhole, and a painted product with an excellent appearance could be obtained.

[Comparative Examples 3 to 5]
In Comparative Examples 3 to 5, coating was performed in the same manner as in Example 1 except for the conditions shown in Table 2 using the following powder coating. The following PE is an abbreviation for polyethylene and Ny is an abbreviation for nylon 12. In Comparative Example 4, air cooling was performed in the same manner as in Example 4, and in Comparative Example 5, post-heating was performed in the same manner as in Example 17.
PET: PET powder coating manufactured by NTT Advanced Technology Co., Ltd., SAPOE-5000 (used in Comparative Example 3)
PE: polyethylene powder coating manufactured by Sumitomo Seika Co., Ltd., Frocene (used in Comparative Example 4)
Ny: Nylon 12 powder paint manufactured by Daicel Degussa Co., Ltd., Daiamide Z2073 (used in Comparative Example 5)
The obtained coating film properties are shown in Table 2. In Comparative Example 3, since a PET powder coating material having a high melting start temperature of 250 ° C. was used, the coating material was not completely melted, and part of the coating material remained in a powdery state, and surface waviness and unevenness were observed. A coating film could not be obtained. In Comparative Examples 4 and 5, since only PE and Ny powder coatings were used, only a coating film having very weak adhesion to the object was obtained. The PE coating film of Comparative Example 4 had a hardness of 5B and was very easily damaged.

[Example 21]
A powder coating material was obtained in the same manner as in Example 1 except that a blade mill (abbreviation in Table 1: BM) manufactured by Nisshin Engineering Co., Ltd. was used as a pulverizer. Table 1 shows the physical properties of the powder coating material. The average particle size was 20 μm, which was very fine and had no whiskers. However, although it was slightly inferior in fluidity, it was a powder having no problem for use in electrostatic coating described later. Further, it was a powder coating material having excellent handling properties and coating properties, with a melting start temperature of 225 ° C. and a melt viscosity of 100 Pa · s.
Next, using the corona charging electrostatic coating gun EP-M10 manufactured by Anest Iwata Co., Ltd., the obtained powder coating was applied to a steel flat plate having a thickness of 1 mm, a length of 100 mm, and a width of 40 mm. Then, it was placed in an electric furnace at 250 ° C. for 3 minutes to melt and adhere the paint, then taken out and cooled in the air for coating. The surface of the object to be coated was blasted to give unevenness. The obtained coating film properties are shown in Table 2.
By using the obtained powder coating material, a coating film having no pinholes and having excellent adhesion, impact resistance, hardness and excellent matte appearance was obtained.

  The present invention relates to a powder coating containing PTT and a method for producing the same, and more specifically, it has excellent surface protection performance such as corrosion resistance and impact resistance, excellent appearance, and good coating properties. A powder coating suitable for powder coating and a method for producing the same are provided. Examples of structures to be painted include shopping carts, steel pipe columns, net baskets, and fences.

Claims (19)

  Powder paint containing polytrimethylene terephthalate.   The powder coating material of Claim 1 whose content rate of the component fuse | melted at the time of coating is 30 to 100 weight%.   The powder coating material of Claim 1 or 2 whose ratio of the polytrimethylene terephthalate with respect to the component fuse | melted at the time of coating is 30 to 100 weight%.   The powder coating material of any one of Claims 1-3 whose average particle diameter is 1-500 micrometers.   The powder coating material of any one of Claims 1-4 whose average particle diameter is 5-250 micrometers.   The powder coating material according to any one of claims 1 to 5, which is mechanically pulverized and / or chemically pulverized.   The powder coating material according to any one of claims 1 to 6, which has been pulverized after heat treatment in advance at 60 to 230 ° C for 1 minute or more.   The powder coating material according to any one of claims 1 to 6, which has been pulverized after heat treatment in advance at 150 to 230 ° C for 5 minutes to 200 hours.   The powder coating material according to claim 7 or 8, wherein the pulverization is performed by mechanical pulverization at normal temperature.   The powder according to any one of claims 1 to 9, wherein at least one functional substance selected from the group consisting of a photocatalyst, a deodorant and an antibacterial agent is added as separate particles from polytrimethylene terephthalate. Body paint.   A structure in which the powder coating material according to any one of claims 1 to 10 is coated on a part of or the entire surface of the structure.   The structure according to claim 11, wherein the structure is one selected from the group consisting of a shopping cart, a steel pipe column, a net basket, and a fence.   A coating film containing polytrimethylene terephthalate formed on a structure.   The coating film of Claim 13 whose ratio of the polytrimethylene terephthalate with respect to the component fuse | melted at the time of coating is 30 to 100 weight%.   A coating film is formed by adhering the powder coating material according to any one of claims 1 to 10 to part or all of the surface of the structure, and subsequently heating and melting the powder coating material. Including painting methods.   A coating method comprising: bringing the powder coating material according to claim 1 into contact with a heated structure to melt the powder coating material to form a coating film.   The method of Claim 16 including heating again after forming a coating film.   18. A method according to any one of claims 15 to 17, comprising cooling the heated powder coating and structure in a gas.   The method according to any one of claims 15 to 17, comprising quenching the heated powder coating material and the object to be coated in a liquid.