JP2016169333A - Powder coating, coated article, method for producing powder coating and microcapsule - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a powder coating that comprises a microcapsule containing ultraviolet absorber and controls the surface charge of the microcapsule.SOLUTION: A powder coating comprises a microcapsule that contains ultraviolet absorber, and has a surface charge absolute value of 9nC/g or more after applied with an electrostatic field under the conditions of -60kV, 20μA.SELECTED DRAWING: None

Description

  The present invention relates to a powder coating material, a coated product, a method for producing a powder coating material, and a microcapsule.

Conventionally used solvent-based paints are accompanied by discharge of volatile organic compounds (VOC) at the time of painting, and are not preferred for use due to environmental problems. Therefore, improvements such as making the paint water-based have been made. Further, as a paint that can be cured by heating, a powder paint that does not contain a volatile organic compound has attracted attention and its use is recommended. Examples of the powder coating include a polyester resin powder coating, and there is a concern that the polyester resin powder coating is insufficient in weather resistance. Thus, for example, the use of fluororesin powder coatings is being studied in applications that require high weather resistance, such as outdoor building materials and road materials, but fluororesin powder coatings are expensive. There is a problem that there is.
Polyester resin powder coating is used in combination with acrylic resin, epoxy resin, urethane resin, etc. for the purpose of improving coating performance such as adhesion, damage resistance, chemical resistance and weather resistance. There is also.

By the way, as a method for producing a polyurethane resin powder, there is a method in which a self-emulsifiable polyurethane resin is mixed with an organic solvent solution of a polyurethane resin, water is gradually added to form an O / W emulsion, and a slurry is formed into a resin powder. It has been proposed (for example, see Patent Document 1).
Further, a heat obtained by dehydrating and drying an aqueous dispersion obtained by dispersing a solution of a mixture comprising a thermoplastic polyurethane resin not containing an isocyanate group and a compound capable of regenerating isocyanate by heating in water in the presence of a dispersion stabilizer. A crosslinkable powdery polyurethane resin composition has been proposed (see, for example, Patent Document 2).
Dispersing a solution of a precursor having an isocyanate group in an aqueous dispersion of a polyurethane resin to form resin particles, the resin particles obtained by attaching a polyurethane resin to the surface of the resin particles, and the resin particles It has been proposed to be used for powder coatings (see, for example, Patent Document 3).
For example, polyurethane resin powder or polyurethane resin particles as described above may be used for the powder coating.

  In addition, many types of ultraviolet absorbers are sold, not limited to liquids and solids, and it has been studied to improve weatherability by adding ultraviolet absorbers to paints.

For example, a manufacturing method for preparing a sol-gel microcapsule filled with a functional molecule or substance such as an ultraviolet absorber, and the use of the sol-gel microcapsule in a paint have been proposed (for example, (See Patent Document 4).
In addition, it has been proposed to use microencapsulated particles that are at least partially encapsulated by a wall material and containing an ultraviolet absorber, and products that are microencapsulated (see, for example, Patent Document 5).

JP-A-5-117407 JP-A-11-116796 JP 2002-284881 A Special table 2003-525100 gazette Special table 2013-514885 gazette

However, when an ultraviolet absorber is added to a paint containing a polyurethane resin powder proposed in Patent Documents 1 and 2, the ultraviolet absorber cannot be fixed to the polyurethane resin particles by chemically primary bonding. There is a problem that the ultraviolet absorber bleeds out from the inside of the coating film to the surface after a long period of time.
Further, in the powder coating proposed in Patent Document 3, the surface of the resin particles formed from the precursor can be dissolved even if the ultraviolet absorber can be dissolved in the solution of the precursor having an isocyanate group. Since the polyurethane resin particles are attached, it is difficult to increase the concentration of the ultraviolet absorber in the powder-coated film.

  Furthermore, Patent Documents 1 to 3 do not disclose a method of using polyurethane resin powder or polyurethane resin particles as a powder coating, or a charge control method that is important when electrostatic powder coating is performed.

  Further, Patent Documents 4 and 5 do not describe the use of microcapsules as a powder coating material, and it is also possible to control the surface charge of microcapsules by redispersing them in an organic solvent. There is no disclosure.

The present invention includes a powder coating containing a microcapsule encapsulating an ultraviolet absorber, the surface charge of the microcapsule being controlled, a coating having a coating film formed using the powder coating, and the powder coating. An object is to provide a manufacturing method.
Another object of the present invention is to provide a microcapsule containing an ultraviolet absorber and having a controlled surface charge.

Specific means for achieving the above-described object are as follows, for example.
<1> A powder coating containing a microcapsule containing an ultraviolet absorber and having an absolute value of surface charge of 9 nC / g or more after applying an electrostatic field under the conditions of −60 kV and 20 μA.
<2> The powder coating according to <1>, wherein the microcapsule includes a hydrophilic nonionic surfactant having a weight average molecular weight of 4000 or more on a capsule wall.
<3> The powder coating material according to <2>, wherein the nonionic surfactant is a polyoxyethylene polyoxypropylene glycol surfactant.
<4> The powder coating material according to any one of <1> to <3>, wherein the microcapsules are redispersed in an organic solvent.
<5> The powder paint according to <4>, wherein the organic solvent is at least one selected from the group consisting of acetone, ethyl acetate, methyl ethyl ketone, and aliphatic alcohol.
<6> The powder coating material according to any one of <1> to <5>, further including at least one of acrylic resin, urethane resin, epoxy resin, ester resin, and fluorine resin.
<7> The absolute value of the surface charge of the microcapsule after applying an electrostatic field under the conditions of −60 kV and 20 μA is the absolute value of the surface charge of the resin after applying the electrostatic field under the conditions of −60 kV and 20 μA. Smaller than <6>.
<8> The powder coating material according to any one of <1> to <7>, which is used for electrostatic powder coating.

  <9> A coated product having a coating film formed using the powder coating material according to any one of <1> to <8>.

  <10> An oil phase containing a polyvalent isocyanate compound and an ultraviolet absorber is added to an aqueous phase containing a hydrophilic nonionic surfactant having a weight average molecular weight of 4000 or more to obtain an emulsion, and the emulsification Reacting the polyisocyanate compound in the liquid to produce a microcapsule encapsulating the ultraviolet absorber; drying the microcapsule to form a powder; and And a step of redispersing in an organic solvent containing a surfactant.

<11> A microcapsule containing an ultraviolet absorber and having an absolute value of surface charge of 9 nC / g or more after applying an electrostatic field under the conditions of −60 kV and 20 μA.
<12> The microcapsule according to <11>, wherein the capsule wall contains a hydrophilic nonionic surfactant having a weight average molecular weight of 4000 or more.
<13> The microcapsule according to <12>, wherein the nonionic surfactant is a polyoxyethylene polyoxypropylene glycol surfactant.
<14> The microcapsule according to any one of <11> to <13>, which is used for a powder coating material.

According to one aspect of the present invention, a powder coating including a microcapsule encapsulating an ultraviolet absorber, the surface charge of the microcapsule being controlled, a coated article having a coating formed using the powder coating, and A method for producing the powder coating material can be provided.
According to one embodiment of the present invention, it is possible to provide a microcapsule that includes an ultraviolet absorber and has a controlled surface charge.

(A) is a graph showing changes in L ^* over time, (b) is a graph showing changes in a ^* over time, and (c) is a graph showing changes in b ^* over time.

Hereinafter, the powder coating material which concerns on one Embodiment of this invention is demonstrated.
In this specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

[Powder paint]
The powder coating material according to this embodiment includes a microcapsule containing an ultraviolet absorber and having an absolute value of surface charge of 9 nC / g or more after applying an electrostatic field under the conditions of −60 kV and 20 μA. The microcapsules contained in the powder coating are microcapsules that can be redispersed in an organic solvent, and the surface charge of the microcapsules is preferably controlled by redispersing the microcapsules in an organic solvent. If necessary, the surface charge of the microcapsule can be adjusted by adding a surface treatment agent (for example, a surfactant) of the microcapsule to the organic solvent.
Furthermore, the powder coating according to the present embodiment includes a microcapsule that includes an ultraviolet absorber and has a controlled surface charge, and is useful for electrostatic powder coating because the surface charge of the microcapsule is controlled. Yes, it may be used as an electrostatic powder coating.

  The powder coating material according to this embodiment includes a microcapsule containing an ultraviolet absorber and having an absolute value of a surface charge of 9 nC / g or more after applying an electrostatic field under the conditions of −60 kV and 20 μA. A microcapsule is a small particle of a micron unit coated with a thin resin film, and encapsulates an ultraviolet absorber. Examples of the resin film include a polyurethane film.

  The microcapsule encapsulating the ultraviolet absorber is, for example, an ultraviolet absorber and a polyvalent isocyanate compound dissolved in an organic solvent or finely dispersed in a solid state and emulsified in an aqueous phase containing a surfactant. It can be prepared by reacting a compound in an aqueous phase.

  In the microcapsules enclosing the ultraviolet absorber, since the ultraviolet absorber is coated on a dense resin film (for example, polyurethane film) in which a three-dimensional crosslinked structure is formed, the powder coating according to the present embodiment is applied to the microcapsule. When this is done, bleeding out of the ultraviolet absorber from the inside of the coating film to the surface is suppressed.

<Ultraviolet absorber>
The microcapsule included in the powder coating according to the present embodiment includes an ultraviolet absorber. Since the UV absorber is included in the microcapsule, the UV absorber is prevented from bleeding out from the inside of the coating film to the surface even after a long period of time, and the effect of the UV absorber is maintained for a long time. be able to.

  As the ultraviolet absorber to be encapsulated, conventionally known ones can be used, for example, benzotriazole compounds, triazine compounds, benzophenone compounds, cyanoacrylate compounds, salicylate compounds, etc. Benzotriazole compounds and triazine compounds are preferred. By using these ultraviolet absorbers, excellent ultraviolet shielding properties can be obtained, and deterioration of the resin component contained in the coating film can be suppressed.

  Examples of the benzotriazole compounds include 2- (2-hydroxy-5-methylphenyl) benzotriazole, 2- (2-hydroxy-5-t-butylphenyl) benzotriazole, 2- (2-hydroxy-3, 5-di-t-butylphenyl) benzotriazole, 2- (2-hydroxy-3-tert-butyl-5-methylphenyl) -5-chlorobenzotriazole, 2- (2-hydroxy-3,5-di- t-butylphenyl) -5-chlorobenzotriazole, 2- (2-hydroxy-3,5-di-t-amylphenyl) benzotriazole, 2- (2-hydroxy-4-octoxyphenyl) benzotriazole, 2 -{2-hydroxy-3- (3,4,5,6-tetrahydrophthalimidomethyl) -5-methylphenyl} benzo Riazor, 2- (2-hydroxy-5-methacryloyloxyethyl phenyl) -2H- benzotriazole.

  Examples of the triazine compound include 2,4-bis (2,4-dimethylphenyl) -6- (2-hydroxy-4-isooctyloxyphenyl) -1,3,5-triazine, 2- [4 ( (2-hydroxy-3-dodecyloxypropyl) -oxy) -2-hydroxyphenyl] -4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine, 2- [4-(( 2-hydroxy-3-tridecyloxypropyl) -oxy) -2-hydroxyphenyl] -4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine, 2- (2,4- And dihydroxyphenyl) -4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine.

A commercially available product may be used as the ultraviolet absorber.
Examples of the benzotriazole compounds include TINUVIN (registered trademark) PS manufactured by BASF, TINUVIN 99-2, TINUVIN 384-2, TINUVIN 900, TINUVIN 928, TINUVIN 1130, and the like.
Examples of the triazine compound include Tinuvin 400, Tinuvin 405, Tinuvin 460, Tinuvin 477, and Tinuvin 479 manufactured by BASF.

  The content of the ultraviolet absorber is preferably adjusted so as to be 3% by mass to 15% by mass, and preferably 5% by mass to 10% by mass with respect to the powder coating material.

<Organic solvent>
The organic solvent used for redispersing the microcapsules encapsulating the ultraviolet absorber is not particularly limited as long as the microcapsules can be redispersed. For example, acetone, ethyl acetate, methyl ethyl ketone, and aliphatic alcohol can be used. It is preferably at least one selected from the group consisting of, and more preferably acetone.

  As an aliphatic alcohol which is an example of an organic solvent, a C2-C10 alcohol is mentioned, Preferably, a C2-C5 alcohol is mentioned. More specifically, the aliphatic alcohol includes ethanol, propanol, propanol, isopropanol, butanol and the like.

<Hydrophilic nonionic surfactant>
In the powder coating according to the present embodiment, the microcapsule preferably contains a hydrophilic nonionic surfactant having a weight average molecular weight (Mw) of 4000 or more on the capsule wall. By using the hydrophilic nonionic surfactant, microcapsules can be suitably produced, and the produced microcapsules can be redispersed in an organic solvent such as acetone.

  When a hydrophilic nonionic surfactant having a weight average molecular weight (Mw) of less than 4000 is used by using a hydrophilic nonionic surfactant having a weight average molecular weight (Mw) of 4000 or more. Rather than agglomerating droplets at the time of microcapsule production, the microcapsules can be more suitably produced.

  When a partially saponified product of polyvinyl alcohol, gelatin, which is a polymer surfactant suitably used for the production of microcapsules, is used, these surfactants remain in the produced microcapsules. It cannot be redispersed in an organic solvent. On the other hand, when microcapsules are produced using the hydrophilic nonionic surfactant, the produced microcapsules can be redispersed in an organic solvent such as acetone, and the microcapsules can be obtained by surface treatment during redispersion. The surface charge can be adjusted.

  The hydrophilic nonionic surfactant is not particularly limited as long as it is a hydrophilic nonionic surfactant having a weight average molecular weight (Mw) of 4000 or more, but droplets aggregate when producing microcapsules. Is preferably a hydrophilic nonionic surfactant having a Mw of 5000 or more, more preferably a hydrophilic nonionic surfactant having a Mw of 7000 or more. Is more preferably 9000 or more hydrophilic nonionic surfactant. In addition, the weight average molecular weight (Mw) of hydrophilic nonionic surfactant is measured as mentioned later using a gel permeation chromatograph (GPC).

  The hydrophilic nonionic surfactant is preferably a hydrophilic nonionic surfactant having a Mw of 50000 or less and a hydrophilicity of Mw of 40000 or less from the viewpoint of solubility in water. The nonionic surfactant is more preferably a hydrophilic nonionic surfactant having a Mw of 30000 or less.

  The hydrophilic nonionic surfactant is preferably a polyoxyethylene polyoxypropylene glycol surfactant from the viewpoint of emulsification. The polyoxyethylene polyoxypropylene glycol-based surfactant is a high molecular weight nonionic surfactant having a polyoxypropylene group as a hydrophobic group (lipophilic group) and a polyoxyethylene group as a hydrophilic group. The aforementioned high molecular weight nonionic surfactant preferably has, for example, an Mw of 4,000 to 50,000, more preferably 9000 to 30,000.

  The polyoxyethylene polyoxypropylene glycol-based surfactant may be a polymer compound having at least one polyoxypropylene group and polyoxyethylene group, and at least one of a polyoxypropylene group and a polyoxyethylene group May be a polymer compound containing two or more.

  The polyoxyethylene polyoxypropylene glycol surfactant is preferably a polymer having one polyoxypropylene group and at least two polyoxyethylene groups. And a polymer having two polyoxyethylene groups is more preferable.

  Examples of the hydrophilic nonionic surfactant include polyoxyethylene polyoxypropylene glycol surfactants, and commercially available products may be used as this surfactant. For example, Epan 485, Epan U-108 manufactured by Daiichi Kogyo Seiyaku Co., Ltd. may be used.

  The hydrophilic nonionic surfactant contained in the aforementioned microcapsule is a hydrophilic nonionic surfactant contained in the aqueous phase when the microcapsule is produced. Here, the microcapsule may contain a surfactant in addition to the hydrophilic nonionic surfactant. For example, when the microcapsule is produced, the hydrophilic ionic interface contained in the aqueous phase is included. It may contain an activator, a lipophilic nonionic surfactant contained in the oil phase, and a surfactant used for surface treatment of microcapsules when redispersed in an organic solvent such as acetone. You may go out.

  Examples of the hydrophilic ionic surfactant contained in the aqueous phase include polyoxyethylene lauryl ether sulfate sodium salt and polyoxyethylene alkyl ether sulfate sodium salt.

  Examples of the lipophilic nonionic surfactant contained in the oil phase include polyoxyethylene polyoxypropylene glycol surfactants. By using a lipophilic nonionic surfactant, it is possible to more suitably suppress the aggregation of droplets during the production of microcapsules, and the particle diameter of the microcapsules can be further reduced. In addition, the efficiency of microcapsule production can be increased.

  The lipophilic nonionic surfactant contained in the oil phase is a polyoxyethylene polyoxypropylene glycol-based polymer having an Mw of 1500 or more from the viewpoint of more suitably suppressing the aggregation of droplets during microcapsule production. A surfactant is preferred, and a polyoxyethylene polyoxypropylene glycol surfactant having an Mw of 1700 or more is more preferred. The lipophilic nonionic surfactant contained in the oil phase is preferably a polyoxyethylene polyoxypropylene glycol-based surfactant having an Mw of 15000 or less, and a polyoxyethylene polyoxypropylene glycol of 10,000 or less. More preferably, it is a system surfactant.

  The powder coating material according to this embodiment includes microcapsules having an absolute value of surface charge of 9 nC / g or more after applying an electrostatic field under the conditions of −60 kV and 20 μA. In the powder coating according to the present embodiment, when the microcapsules encapsulating the ultraviolet absorber are redispersed in the organic solvent, the surface charge of the microcapsules can be adjusted by the surface treatment of the microcapsules. The absolute value of the surface charge can be adjusted to 9 nC / g or more. Thereby, when using the powder coating material containing the resin mentioned later for electrostatic coating, the component which adheres electrostatically to a to-be-coated object can be controlled suitably, and a desired coated material can be manufactured.

  The absolute value of the surface charge of the microcapsule after applying an electrostatic field under the conditions of −60 kV and 20 μA is preferably adjusted to 40 nC / g or less, more preferably 30 nC / g or less, and 20 nC / g. It is more preferable to adjust to the following.

  Examples of the method for adjusting the surface charge of the microcapsule include a method in which a microcapsule encapsulating an ultraviolet absorber is redispersed in an organic solvent, and a surfactant is added to the organic solvent to surface-treat the microcapsule. .

  Examples of the surfactant added to the organic solvent include polyoxyethylene alkyl ether, polyoxyethylene lauryl ether, polyoxyethylene oleyl ether and the like. Moreover, as a surfactant added to the organic solvent, commercially available products may be used, for example, Emulgen 109P, Emulgen 130K, Emulgen 306P, etc. manufactured by Kao Corporation may be used. By appropriately selecting a surfactant to be added to the organic solvent, the surface charge of the microcapsules can be adjusted.

  In the present invention, the surface charge of the microcapsule after the surface treatment is measured using an electrostatic powder spray gun (Colo-900T, manufactured by Hangzhou Color Powder Coating Equipment Co. Ltd.) under the condition of −60 kV and 20 μA. Is a value measured after applying.

<Resin>
The powder coating according to the present embodiment may further include a resin used for the powder coating, for example, at least one of acrylic resin, urethane resin, epoxy resin, ester resin (also referred to as polyester resin), and fluorine resin. The resin may be included. Of these resins, one type of resin may be used, or two or more types of resins may be used in combination. Furthermore, it is preferable that the powder coating material according to the present embodiment further includes at least one of a polyester resin and a fluorine resin. Thereby, since the powder coating material contains the microcapsules encapsulating the ultraviolet absorber and the resin serving as the base of the coating film, it can be suitably used, for example, for electrostatic powder coating. Moreover, since the microcapsules encapsulating the ultraviolet absorber are particles coated with a resin film, they have a high affinity with these resins.

(Polyester resin)
The polyester resin used in this embodiment is a resin obtained by reacting a carboxylic acid and a polyhydric alcohol. As the polyester resin, a polyester resin contained in a commercially available powder paint may be used, and a powder paint containing a microcapsule containing an ultraviolet absorber and a commercially available powder paint containing a polyester resin are mixed. And it is good also as the powder coating material which concerns on this embodiment.

  In general, polyester resins are inexpensive, but have a problem of poor weather resistance. However, in this embodiment, by combining a microcapsule encapsulating an ultraviolet absorber and a polyester resin, a powder coating material that is excellent in weather resistance over a long period of time and is inexpensive can be obtained.

  Examples of the carboxylic acid component used in the production of the polyester resin 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, tri Polycarboxylic acids such as merit acid and pyromellitic acid, lower alkyl esters of these polycarboxylic acids and their anhydrides, or hydroxycarboxylic acids such as malic acid, tartaric acid, 1,2-hydroxystearic acid and paraoxybenzoic acid Etc.

  Moreover, as a polyhydric alcohol component used for manufacture of a polyester resin, for example, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4 -Butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, 1,10-decanediol, neopentyl glycol, spiroglycol, 1,10-decanediol, 1,4- Examples include cyclohexanedimethanol, trimethylolethane, trimethylolpropane, glycerin, pentaerythritol and the like.

  In addition, from the viewpoint of improving the weather resistance, a fluorine resin, which will be described later, may be added to the powder coating material according to this embodiment together with the polyester resin. Moreover, you may add an epoxy resin and a urethane resin for the improvement of other coating-film physical properties.

(Fluorine resin)
The fluorine resin used in the present embodiment is a fluorine-containing polymer obtained by polymerizing or copolymerizing a fluorine-containing monomer. Examples of the fluororesin include polytetrafluoroethylene (PTFE) resin, polyvinylidene fluoride (PVDF) resin, and polyvinyl fluoride (PVF) resin. In addition, as the fluororesin, a fluororesin contained in a commercially available powder paint may be used, and a powder paint containing a microcapsule encapsulating an ultraviolet absorber and a commercially available powder paint containing a fluororesin are mixed. And it is good also as the powder coating material which concerns on this embodiment.

Typical examples of the fluorine-containing monomer include vinyl fluoride, vinylidene fluoride, trifluoroethylene, tetrafluoroethylene, bromotrifluoroethylene, chlorotrifluoroethylene, pentafluoropropylene, hexafluoropropylene, and the like. It is done.
The fluororesin may be copolymerized with a polymerizable monomer other than the above fluorine-containing monomers, and 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.

<Other additives>
The powder coating material according to the present embodiment may contain other additives as long as the effects of the present invention are not impaired. Other additives include, but are not limited to, antioxidants, light stabilizers, flame retardants, fillers, colorants, crosslinking agents, viscosity modifiers, antifoaming agents, leveling agents, anti-fogging agents, appearance improvers, etc. Is mentioned.

  In the powder coating according to the present embodiment, the absolute value of the surface charge of the microcapsule after applying the electrostatic field under the conditions of −60 kV and 20 μA is the resin after applying the electrostatic field under the conditions of −60 kV and 20 μA. It is preferably smaller than the absolute value of the surface charge. During electrostatic coating, it is possible to suitably control components that adhere electrostatically to the object to be coated, and to manufacture a desired painted object. Specifically, the base resin can be preferentially attached to the application surface by generating a charge opposite to the microcapsules and the resin on the application surface of the object to be coated.

  Resin contained in commercially available powder coatings has a surface charge of −20 nC / g to −130 nC when the surface charge after applying an electrostatic field under the conditions of −60 kV and 20 μA is measured with Electrostatic Charge Meter (manufactured by Trek Japan Co., Ltd.). / G or so. Therefore, the surface charge of the microcapsules after applying the electrostatic field under the conditions of −60 kV and 20 μA may be adjusted according to the resin contained in the powder coating used.

[Painted material]
A coated product having a coating film formed using a powder coating material including a microcapsule enclosing a resin and an ultraviolet absorber is also included in the scope of the present invention. The coated material is not particularly limited as long as it can be produced by powder coating, and examples thereof include building materials, road materials, buildings, vehicle bodies, and electronic devices.

[Production method of powder coating]
Hereinafter, the manufacturing method of the powder coating material which concerns on one Embodiment of this invention is demonstrated. In the method for producing a powder coating according to the present embodiment, a polyisocyanate compound and an ultraviolet absorber are added to an aqueous phase containing a hydrophilic nonionic surfactant having a weight average molecular weight (Mw) of 4000 or more. A step of producing a microcapsule encapsulating the ultraviolet absorber by adding the oil phase containing to make an emulsion, reacting the polyvalent isocyanate compound in the emulsion, and drying the microcapsule to form a powder And a step of redispersing the microcapsules in powder form in an organic solvent containing a surfactant.

  First, the manufacturing method of the powder coating material which concerns on this embodiment includes the process of producing the microcapsule which includes an ultraviolet absorber. In this step, an oil phase containing a polyvalent isocyanate compound and an ultraviolet absorber is added to an aqueous phase containing a hydrophilic nonionic surfactant having an Mw of 4000 or more to obtain an emulsion, A microcapsule encapsulated by reacting the polyvalent isocyanate compound in the emulsion and encapsulating an ultraviolet absorber can be produced.

The hydrophilic nonionic surfactant having an Mw of 4000 or more is preferably added to the aqueous phase so that the concentration in the emulsion is 0.5% by mass to 5% by mass.
When the polyvalent isocyanate compound in the emulsion is reacted, the reaction temperature is preferably 30 ° C. to 50 ° C., and the reaction time is preferably 3 hours to 5 hours.

  In the step of producing a microcapsule, by using a hydrophilic nonionic surfactant having an Mw of 4000 or more, droplets can be prevented from agglomerating during the production of the microcapsule, and the microcapsule is more suitably produced. Can do. Furthermore, the produced microcapsules can be redispersed in an organic solvent such as acetone, and the surface charge of the microcapsules can be adjusted by surface treatment during redispersion.

  In the method for producing a powder coating according to the present embodiment, the above-mentioned hydrophilic ionic surfactant may be added to the aqueous phase containing a hydrophilic nonionic surfactant, and a polyvalent isocyanate compound may be added. And the above-described lipophilic nonionic surfactant may be added to the oil phase containing the ultraviolet absorber. The hydrophilic ionic surfactant is preferably added to the aqueous phase so that the concentration in the emulsion is 0.5% by mass to 5% by mass, and the lipophilic nonionic surfactant is It is preferable to add to the oil phase so that the concentration in the emulsion is 0.5% by mass to 5% by mass.

  The manufacturing method of the powder coating material which concerns on this embodiment includes the process of making the produced microcapsule into powder after the process of producing a microcapsule. The dried microcapsules may be classified by sieving. At this time, the microcapsules are preferably sieved so that the average particle diameter is between 1 μm and 100 μm.

  The method for producing a powder coating according to the present embodiment includes a step of redispersing the microcapsules in powder in an organic solvent containing a surfactant after the step of drying the microcapsules into powder. . When redispersed in an organic solvent, a surfactant or the like used for the surface treatment of the microcapsules may be added to the organic solvent. By redispersing in an organic solvent, the surface charge of the microcapsules can be controlled. For example, the surface charge can be adjusted to a desired value by adding a desired surfactant to the organic solvent and redispersing the microcapsules in the organic solvent.

[Microcapsule]
A microcapsule containing an ultraviolet absorber and having an absolute value of surface charge of 9 nC / g or more after applying an electrostatic field under the conditions of −60 kV and 20 μA is also included in the scope of the present invention. Such a microcapsule can be produced as described above using a hydrophilic nonionic surfactant having a weight average molecular weight of 4000 or more. The microcapsules according to this embodiment are preferably used for powder coatings, and more preferably used for electrostatic powder coating.

  Next, although one mode of the present invention is explained based on the following examples, the present invention is not limited to the examples.

[Example 1]
<Preparation of microcapsule solution>
A microcapsule solution was prepared as follows.
First, a polyoxyethylene polyoxypropylene glycol-based surfactant having an ethylene oxide content of about 85% by mass and a polypropylene glycol molecular weight of 1200 (Epan 485, PS (polystyrene) conversion, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 1.6 mass parts of weight average molecular weight 11000 ± 1000) and polyoxyethylene lauryl ether sulfate sodium salt (manufactured by Sanyo Chemical Industries, Ltd., Carribbon EN-200) The aqueous phase was mixed with the part.
26 parts by weight of Takenate D110N (manufactured by Sumitomo Chemical Bayer Urethane Co., Ltd.) as a polyisocyanate compound that is an adduct of xylylene diisocyanate, an ethylene oxide content of about 30% by mass, and a polypropylene glycol molecular weight of 1200 Polyoxyethylene polyoxypropylene glycol surfactant (Daiichi Kogyo Seiyaku Co., Ltd., Epan U-103, PS equivalent weight average molecular weight 9500 ± 500) 2.0 parts by mass dissolved in ethyl acetate 23 parts by mass Phased.
The aforementioned oil phase was gradually added to the aforementioned aqueous phase, and then stirred to disperse to obtain an emulsion. This emulsion was reacted for 4 hours while stirring in a warm bath kept at 40 ° C. to prepare a microcapsule solution having a particle size of 30 μm to 60 μm.

  The weight average molecular weight (Mw), number average molecular weight (Mn), and polydispersity (Mw / Mn) in terms of polystyrene of the polyoxyethylene polyoxypropylene glycol-based surfactant and nonionic surfactant used in the examples are , Using a GPC system (manufactured by JASCO Corporation), tetrahydrofuran as an eluent and KF-805L (manufactured by Showa Denko KK) as a separation column, using a polystyrene calibration curve. Specifically, a polyoxyethylene polyoxypropylene glycol surfactant or a nonionic surfactant is dissolved in tetrahydrofuran at 40 ° C. to prepare a sample solution having a concentration of 0.5% by mass, and 0.1 ml of the sample solution Was introduced into the column at a temperature of 40 ° C. and 1 ml / min and measured.

<Preparation of microcapsule powder>
The microcapsule solution prepared as described above was diluted with water and decanted three times, and then dried at 100 ° C. for several minutes. The microcapsule powder obtained by drying was classified with a stainless steel sieve having an opening diameter of 180 μm.

<Preparation of microcapsules for powder coatings>
The microcapsule powder after classification was redispersed with acetone. The re-dispersed microcapsule powder was classified with a 100 μm sieve and then dried in an oven to obtain a powder coating microcapsule (powder coating sample).

[Example 2]
A powder coating microcapsule (powder coating sample) was prepared in the same manner as in Example 1 except that Epan U-108 was used instead of Epan 485.
Note that Epan U-108 has a polyoxyethylene polyoxypropylene glycol-based surfactant having an ethylene oxide content of about 80% by mass and a polypropylene glycol molecular weight of 3250 (Daiichi Kogyo Seiyaku Co., Ltd., PS equivalent weight). Average molecular weight 28000).

Example 3
A powder coating microcapsule (powder coating sample) was prepared in the same manner as in Example 1 except that Epan 410 was used instead of Epan U-103.
Epan 410 has a polyoxyethylene polyoxypropylene glycol-based surfactant having an ethylene oxide content of about 10% by mass and a polypropylene glycol molecular weight of 1200 (Daiichi Kogyo Seiyaku Co., Ltd., PS-converted weight average molecular weight). 1900).

Example 4
Instead of re-dispersing with acetone containing no nonionic surfactant, 2.3 mass of nonionic surfactant (Emulgen 109P, Mw = 1102) having an HLB value of 13.6 was obtained. A microcapsule for powder coating (powder coating sample) was prepared in the same manner as in Example 1 except that it was re-dispersed using an acetone solution containing 1%.

Example 5
Instead of redispersing with acetone containing no nonionic surfactant, 2.3 mass of nonionic surfactant having an HLB value of 18.1 (manufactured by Kao Corporation, Emulgen 130K, Mw = 3559) A microcapsule for powder coating (powder coating sample) was prepared in the same manner as in Example 1 except that it was re-dispersed using an acetone solution containing 1%.

Example 6
Instead of re-dispersing with acetone containing no nonionic surfactant, 2.3 mass of nonionic surfactant (Emulgen 306P, Mw = 1026, manufactured by Kao Corporation) having an HLB value of 9.4 A microcapsule for powder coating (powder coating sample) was prepared in the same manner as in Example 1 except that it was re-dispersed using an acetone solution containing 1%.

<Electrostatic powder coating experiment>
The charge amount of the powder coating samples of Examples 1, 4, 5, and 6 was measured as follows.
First, an electrostatic powder spray gun (Colo-900T, manufactured by Hangzhou Color Powder Coating Equipment Co. Ltd.) was applied to 50 g of a powder coating sample, and an electrostatic field was applied under conditions of an applied voltage of −60 kV and a current of 20 μA. Then, several g of the powder coating sample was discharged from the spray gun and collected by a collection device (cylindrical filter paper). The charge amount of the collected powder coating sample was measured with an Electrostatic Charge Meter (manufactured by Trek Japan Co., Ltd.).
The results are as shown in Table 1.

  In Examples 1 to 6, it was possible to redisperse the microcapsule powder after drying in an organic solvent such as acetone. In addition, from the results of charge measurement in Examples 1, 4, 5, and 6, the surface charge of the microcapsules can be adjusted by adding a surfactant to an organic solvent such as acetone to surface-treat the microcapsules. I found out.

  Here, when the above-described electrostatic powder coating experiment was performed on a commercially available powder coating (for example, PVDF coating or polyester coating), the charge amount of the resin component of the powder coating was −20 nC / g to It was about −130 nC / g. Therefore, by adjusting the surface charge of the microcapsule powder, the surface charge of the microcapsule powder can be made smaller than the surface charge of the resin component of the powder coating, and the microcapsule enclosing the ultraviolet absorber, It has been found that a paint containing a resin component is particularly useful as an electrostatic powder paint.

Example 7
A microcapsule solution was prepared in the same manner as in Example 1 except that 9.75 parts by mass of an ultraviolet absorber (manufactured by BASF, Tinuvin 400) was added to the oil phase when preparing the microcapsule solution. Then, in the same manner as in Example 1, after producing microcapsule powder (microcapsule powder including an ultraviolet absorber), a powder coating sample was obtained.

<Weather resistance test>
The powder coating sample obtained in Example 7 was mixed with a powder coating (green) containing a colored polyester resin to prepare a weather resistance test coating. At this time, the powder coating sample and the powder coating were mixed so that the addition amount of the ultraviolet absorber was 5, 7.5, and 10% by mass with respect to the powder coating. For comparison, a coating material for weather resistance test using only a powder coating material (addition amount of UV absorber is 0% by mass) was also prepared.
The weather resistance test paint was evenly applied to the slide glass through a metal sieve, and heat-treated at 180 ° C. for 10 minutes in a dry oven to obtain a weather resistance test sample. The sample for weather resistance test after heat treatment was irradiated with a super xenon weatherometer (SX-75, 180 kW lamp, manufactured by Suga Test Instruments Co., Ltd.), and the number of colors (L ^* , a ^* , b ^* ) was measured. The results are shown in (a) to (c) of FIG. FIGS. 1A to 1C are graphs showing changes in L ^* , a ^* , and b ^* over time, respectively.

As shown in FIG. 1 (a), when only a powder coating containing a polyester resin is used, the increase in L ^* due to light irradiation is higher than when a powder coating sample and a powder coating are mixed. It was remarkable. In addition, in the case of only a powder coating containing a polyester resin, the surface was a mirror surface when not irradiated, but the surface became clouded by light irradiation, and fine irregularities were formed on the surface by light irradiation. The formation of a large number was confirmed by microscopic observation.
On the other hand, as shown in FIGS. 1B and 1C, the hues (a ^* , b ^* ) of all the weather resistance test samples are almost constant even when light irradiation is performed. There was no change in taste.
Therefore, when only a powder coating containing a polyester resin is used, the polyester resin deteriorates by light irradiation, so that L ^* increases, and when a sample for powder coating and a powder coating are mixed, an ultraviolet absorber It was found that the inclusion of the microcapsules encapsulating the polyester suppresses deterioration of the polyester resin due to light irradiation and suppresses an increase in L ^* .
Moreover, since the weather resistance of the polyester resin powder coating material can be improved, it is presumed that the weather resistance can be improved, for example, for a powder coating material in which a polyester resin and a fluorine resin are mixed.

[Comparative Example 1]
A microcapsule solution was prepared in the same manner as in Example 1 except that PVA217E (manufactured by Kuraray Co., Ltd.) was used as an aqueous phase surfactant instead of Epan 485 and Caribon EN-200. Capsule powder was prepared. The produced microcapsule powder could not be redispersed in either acetone or methanol.

[Comparative Example 2]
The emulsification and reaction was carried out in the same manner as in Example 1 except that only the carrier ribbon EN-200 was used instead of Epan 485 and carrier ribbon EN-200 as the aqueous phase surfactant. Agglomerated and microcapsules could not be obtained.

[Comparative Example 3]
Example 1 except that Emulgen 109P (manufactured by Kao Corporation, HLB value = 13.6, Mw = 1102) was used instead of Epan 485 and Caribon EN-200 as the aqueous phase surfactant. Then, emulsification and reaction were performed, but the liquid droplets aggregated during the reaction, and microcapsules could not be obtained.

[Comparative Example 4]
Except for using Emulgen 130K (manufactured by Kao Corporation, HLB value = 18.1, Mw = 3559) instead of Epan 485 and Caribon EN-200 as the aqueous phase surfactant, the same as in Example 1. Then, emulsification and reaction were performed, but the liquid droplets aggregated during the reaction, and microcapsules could not be obtained.

Claims (14)

  A powder coating containing a microcapsule containing an ultraviolet absorber and having an absolute value of a surface charge of 9 nC / g or more after applying an electrostatic field under the conditions of −60 kV and 20 μA.   The powder coating according to claim 1, wherein the microcapsule includes a hydrophilic nonionic surfactant having a weight average molecular weight of 4000 or more on a capsule wall.   The powder coating material according to claim 2, wherein the nonionic surfactant is a polyoxyethylene polyoxypropylene glycol-based surfactant.   The powder coating material according to any one of claims 1 to 3, wherein the microcapsules are redispersed in an organic solvent.   The powder coating material according to claim 4, wherein the organic solvent is at least one selected from the group consisting of acetone, ethyl acetate, methyl ethyl ketone, and aliphatic alcohol.   The powder coating material according to any one of claims 1 to 5, further comprising at least one of an acrylic resin, a urethane resin, an epoxy resin, an ester resin, and a fluorine resin.   The absolute value of the surface charge of the microcapsule after applying an electrostatic field under the conditions of −60 kV and 20 μA is smaller than the absolute value of the surface charge of the resin after applying the electrostatic field under the conditions of −60 kV and 20 μA. The powder coating material according to claim 6.   The powder coating material according to any one of claims 1 to 7, which is used for electrostatic powder coating.   The coated object which has a coating film formed using the powder coating material of any one of Claims 1-8. An oil phase containing a polyvalent isocyanate compound and an ultraviolet absorber is added to an aqueous phase containing a hydrophilic nonionic surfactant having a weight average molecular weight of 4000 or more to form an emulsion, and the emulsion in the emulsion Reacting the polyvalent isocyanate compound to produce a microcapsule encapsulating the ultraviolet absorber;
Drying the microcapsules into a powder;
And redispersing the microcapsules in powder form in an organic solvent containing a surfactant.   A microcapsule containing an ultraviolet absorber and having an absolute value of surface charge of 9 nC / g or more after applying an electrostatic field under the conditions of −60 kV and 20 μA.   The microcapsule according to claim 11, wherein the capsule wall contains a hydrophilic nonionic surfactant having a weight average molecular weight of 4000 or more.   The microcapsule according to claim 12, wherein the nonionic surfactant is a polyoxyethylene polyoxypropylene glycol-based surfactant.   The microcapsule according to any one of claims 11 to 13, which is used for a powder coating material.