JP2006198511A - Coating film forming method and gloss adjusting process of coating film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gloss adjusting process of a coating film which adjusts the surface gloss (degree of matting) of a cured coating film obtained by using a photo-polymerization composition (such as a matting powder coating). <P>SOLUTION: The coating film is formed on the surface of a substrate by a preliminary curing step of irradiating the coating film formed by the photo-polymerization composition which is solid or viscous at room temperature (for example, a photo-polymerization composition containing a filler such as a matting agent) with active rays (such as ultraviolet ray) of a predetermined radiation energy (G1) to partially cure the coating film, a heating step of heating the coating film and a curing step of irradiating the coating film with the active rays (such as ultraviolet ray) of a predetermined radiation energy (G2) to cure. The surface gloss of the cured coating film is adjusted by G1. The greater the G1 is, the lower the surface gloss of the coating film is. For example, G1/G2 is adjusted within a range of 1/99 to 3/70. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for forming a coating film using a photopolymerizable composition and a method for adjusting the gloss of the coating film.

  Conventionally, a method of forming a cured coating film by irradiating ultraviolet rays onto a coating film formed by applying an ultraviolet curable powder coating material to a substrate is known.

  For example, JP-A-8-301957 (Patent Document 1) discloses a radiation curable powder composition containing a terminal methacryl group-containing crystalline polyester. This document describes a radiation curable powder composition deposited on an article by spraying with a triboelectric gun or electrostatic gun (electrostatic coating) or by a fluidized bed (fluid dipping method) at 80-150 ° C. A coating method is described in which after being melted by heating, it is irradiated with ultraviolet rays or an accelerated electron beam. In this document, an ultraviolet curable powder composition deposited on an article is heated and melted at 80 to 150 ° C. in a forced circulation oven or using an infrared lamp, spread, It is described that a uniform continuous coating is obtained.

  Japanese Patent Application Laid-Open No. 2002-221506 (Patent Document 2) discloses a powder coating for applying to a porous substrate, and an ultraviolet curable powder coating containing wax. In this document, the powder coating adhered to the porous substrate by electrostatic coating is heated and melted, and then cured by irradiation with ultraviolet rays, and the occurrence of foaming marks is suppressed by wax. Is described.

However, in the case of electrostatic coating, the coating efficiency to the substrate is about 50 to 70%, and the paint that has not been coated is collected or discarded. Since the particle size distribution of the collected powder paint is different from the particle size distribution of a normal paint, if the collected powder paint is used again for electrostatic coating, the appearance of the coating film may be impaired. Moreover, a uniform and thick film cannot be formed on an electrically insulating substrate such as a wood material. Furthermore, it is difficult to control the coating amount and it is difficult to form a coating film having a good appearance. Furthermore, when the base material is a wood material or the like, high-temperature heating is difficult. In either case, since the powder coating wraps around the back surface of the base material, it is difficult to apply only to a predetermined surface of the base material. Furthermore, in any of these methods, in order to form a smooth coating film, the coating film is heated and melted, and then the coating film is irradiated with ultraviolet rays and cured. Therefore, it is suitable for forming a highly glossy coating film. However, even if an attempt is made to form a coating film with a low gloss using a matting agent, the gloss of the coating film becomes high. Therefore, it is difficult to form a coating film having a desired gloss.
JP-A-8-301957 (Claim 1, Claim 18, Paragraph Number [0045], Paragraph Number [0046]) JP-A-2002-221506 (Claim 1, Example)

  Accordingly, an object of the present invention is to provide a coating film forming method capable of adjusting the gloss of a cured coating film by a simple operation and a method for adjusting the gloss of a cured coating film.

  Another object of the present invention is to form a coating film that can adjust the gloss (matte level) of a cured coating film by a simple operation even for a coating film containing a filler (for example, a matted coating film). The object is to provide a method and a method for adjusting the gloss of a cured coating film.

  Still another object of the present invention is to provide a coating film forming method capable of forming a uniform and thick film with high coating efficiency.

  As a result of intensive studies to achieve the above-mentioned problems, the inventors of the present invention applied actinic rays to a coating film formed of a photopolymerizable composition that is solid or viscous at room temperature to be partially cured (precured). In the method of curing after irradiation with actinic rays, and increasing the degree of precuring (irradiation energy of actinic rays), the gloss of the cured coating is found to be reduced, completing the present invention. did.

  That is, in the coating film forming method of the present invention, a coating film formed of a photopolymerizable composition that is solid or viscous at room temperature is irradiated with actinic rays (for example, ultraviolet rays) to be partially cured (precured). Then, the coating film is heated, and further, the heated coating film is irradiated with actinic rays (for example, ultraviolet rays) to be cured. The photopolymerizable composition may be, for example, a photopolymerizable composition having a viscosity of 200 Pa · s (= 2000 poise) or more at 25 ° C. Moreover, you may form the coating film of a photopolymerizable composition by melt coating, for example. Furthermore, the precured coating film may be flattened by heating.

  The photopolymerizable composition may contain a filler, and the amount of the filler used is 10 to 300 parts by weight with respect to 100 parts by weight of the photocurable resin constituting the photopolymerizable composition. There may be. The filler may be composed of at least a matting agent, and the amount of the matting agent used is 30 to 120 parts by weight with respect to 100 parts by weight of the photocurable resin constituting the photopolymerizable composition. There may be.

  In the present invention, when the total amount of irradiation energy G1 of actinic rays to the coating film formed from the photopolymerizable composition and irradiation energy G2 of actinic rays to the coating film after heating is 100, G1 / G2 is 1 / 99-30 / 70 may be sufficient.

  In the present invention, a pre-curing step of partially curing the coating film formed of the photopolymerizable composition by irradiation with actinic rays, a heating step of heating the partially cured coating film, and after heating And a method of adjusting the gloss of the cured coating film by the irradiation energy of the actinic ray in the preliminary curing process.

  According to the present invention, the coating film formed of the photopolymerizable composition that is solid or viscous at room temperature is cured through the preliminary curing process, the heating process, and the curing process, so that the gloss of the cured coating film is increased. Can be adjusted. That is, a cured film having a low gloss can be formed by increasing the degree of preliminary curing. The gloss of the cured coating film can also be adjusted by a filler (particularly a matting agent). Therefore, the gloss of the cured coating film can be adjusted in a wide range by combining the degree of preliminary curing and the filler content. In addition, according to the present invention, since a solid or viscous photopolymerizable composition is melt coated at room temperature, a uniform and thick film can be formed with high coating efficiency. Furthermore, according to the present invention, the surface gloss of the cured coating film can be adjusted by a simple operation of adjusting the irradiation energy of actinic rays in the preliminary curing, and a cured coating film having a desired surface gloss can be formed.

  In the present invention, a pre-curing step in which a coating film (uncured coating film) formed of the photopolymerizable composition is irradiated with actinic rays to be partially cured, and a heating step in which the partially cured coating film is heated ( For example, a cured coating film is formed on the surface of the base material by a heating process in which the coating film surface is heated to flatten the surface and a curing process in which the heated coating film is irradiated with an actinic ray to be cured.

[Photopolymerizable composition]
The photopolymerizable composition is solid or viscous at room temperature (temperature: 15 to 25 ° C.), and the viscosity of the viscous photopolymerizable composition is, for example, 200 Pa · s or more, usually 300 Pa · s at 25 ° C. s or more, preferably 500 Pa · s or more, and more preferably 1000 Pa · s or more. The viscosity of the photopolymerizable composition can be measured using, for example, a B-type viscometer, but usually cannot be measured at 25 ° C. in many cases. In such a case, it may be obtained by extrapolating from the relationship between the measured value at a high temperature by the B-type viscometer and the temperature.

  The solid or viscous photopolymerizable composition may be flattened by heating the coating film, or may not be able to form a uniform coating film only by applying to the substrate and cooling. .

  The photopolymerizable composition may be composed of, for example, a photocurable resin and a photopolymerization initiator. The photocurable resin is a resin that is solid at room temperature (temperature 15 to 25 ° C.) and has a photopolymerizable group (for example, an α, β-ethylenically unsaturated bond group such as a (meth) acryloyl group). If it is, it will not specifically limit, A photocurable polyester resin, a photocurable acrylic resin, a photocurable epoxy (meth) acrylate resin, a photocurable urethane (meth) acrylate resin, a photocurable silicone resin etc. Illustrated. These photocurable resins can be used alone or in combination of two or more.

  The photo-curable polyester resin includes a saturated or unsaturated polyester resin having a functional group (hydroxyl group, carboxyl group, etc.) and a polymerizable unsaturated compound having a reactive group with respect to the functional group (for example, reaction with respect to the functional group). Polymerizable group-containing polyester resin (for example, (meth) acryloyl group-containing polyester resin), photocurable unsaturated polyester-based resin produced by the reaction of a reactive group and a (meth) acryloyl group-containing polymerizable compound) Examples thereof include resins (for example, polyester resins obtained by using unsaturated dicarboxylic acid components such as maleic anhydride and maleic acid as dicarboxylic acid components). As the photocurable polyester resin, a polyester resin having a (meth) acryloyl group is usually used.

  The polyester-based resin having a functional group includes a polycarboxylic acid component containing a dicarboxylic acid component as a main component (for example, 70 to 100 mol%, preferably 80 to 100 mol%, more preferably about 90 to 100 mol%), It may be a product resulting from an esterification reaction with a polyol component containing a diol component as a main component (for example, about 70 to 100 mol%, preferably about 80 to 100 mol%, more preferably about 90 to 100 mol%).

Examples of the dicarboxylic acid component include aliphatic dicarboxylic acids (for example, C _2-20 aliphatic dicarboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid), aromatic Dicarboxylic acids (for example, C _8-16 aromatic dicarboxylic acids such as isophthalic acid, terephthalic acid, phthalic anhydride, phthalic acid, naphthalenedicarboxylic acid or the like), alicyclic dicarboxylic acids (for example, 1,4- Examples thereof include _C8-12 alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid and tetrahydrophthalic acid or anhydrides thereof. The dicarboxylic acid component may be a reactive derivative such as a lower alkyl ester (C _1-3 alkyl ester such as methyl ester). These dicarboxylic acid components can be used alone or in combination of two or more.

Among these dicarboxylic acid components, linear C _6-16 aliphatic dicarboxylic acid (especially linear C _6-12 aliphatic dicarboxylic acid), C _8-12 aromatic dicarboxylic acid (especially benzene dicarboxylic acid, naphthalene dicarboxylic acid) Acid) and at least one dicarboxylic acid selected from C _8-12 alicyclic dicarboxylic acids (particularly C _8-10 alicyclic dicarboxylic acids).

  The dicarboxylic acid component may be used in combination with a polycarboxylic acid (for example, a tricarboxylic acid such as trimellitic acid or pyromellitic acid, a tetracarboxylic acid, or an acid anhydride thereof) as necessary to introduce a branched structure.

Examples of the diol component include alkylene glycol (for example, C _2-12 alkylene glycol such as ethylene glycol, propylene glycol, trimethylene glycol, tetramethylene glycol, 1,3-butanediol, neopentyl glycol, hexanediol), ( Poly) oxyalkylene glycol (for example, (poly) oxy C _2-4 alkylene glycol such as diethylene glycol and dipropylene glycol), alicyclic diol (for example, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, etc.) C _6-10 cycloalkanediol), aromatic diols (for example, bisphenols such as bisphenol A, bisphenols such as bisphenol A-C _2-4 alkylene oxide adducts, and C _2-4 alkyleneo And adducts with xoxides). These diol components can be used alone or in combination of two or more. Among these diol components, at least one selected from C _2-8 alkylene glycol (ethylene glycol, etc.) and C _6-8 cycloalkanediol (1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, etc.) Often used.

  The diol component may be used in combination with a polyol component (for example, a triol such as glycerin or trimethylolpropane, a tetraol such as pentaerythritol, etc.) as necessary in order to introduce a branched structure.

  The concentration of the functional group (carboxyl group, hydroxyl group) of the polyester resin may be in a range where photopolymerizability can be imparted by reaction with the polymerizable unsaturated compound, for example, acid value or hydroxyl value (OH value). It may be about 5 to 200 mgKOH / g, preferably 10 to 150 mgKOH / g, more preferably about 20 to 100 mgKOH / g.

Examples of the polymerizable compound having a reactive group with respect to the functional group of the polyester resin (for example, a polymerizable compound having a reactive group with respect to the functional group of the polyester resin and a (meth) acryloyl group) include, for example, a carboxyl group Compounds having a reactive group with respect to [for example, glycidyl (meth) acrylate, hydroxyalkyl (meth) acrylate such as hydroxy C _2-6 alkyl (meth) acrylate (hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, etc.), etc. Etc.], a compound having a reactive group with respect to a hydroxyl group [for example, vinyl isocyanate, (meth) acrylate having an isocyanate group (for example, polyisocyanate such as tolylene diisocyanate, isophorone diisocyanate) Reaction product of the component with the hydroxyalkyl (meth) acrylate), unsaturated carboxylic acid ((meth) acrylic acid, crotonic acid, etc.) or reactive derivative thereof (anhydrous (meth) acrylic acid, (meth) acrylic) Acid chloride and the like)] and the like. These polymerizable compounds can be used alone or in combination of two or more depending on the type of functional group of the polyester resin.

The photocurable polyester resin may be crystalline (including semi-crystalline) or non-crystalline. In order to obtain a crystalline polyester resin, it is advantageous to use a dicarboxylic acid in which a carboxyl group is substituted on the symmetry axis of the molecule and / or a diol in which a hydroxyl group is substituted on the symmetry axis of the molecule. Examples of such symmetric (or symmetric structure) dicarboxylic acid include linear C _4-16 aliphatic dicarboxylic acid (particularly linear C _6-12 aliphatic dicarboxylic acid) and symmetric cyclic dicarboxylic acid (terephthalate). Examples thereof include at least one dicarboxylic acid selected from aromatic dicarboxylic acids such as acids and alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid. Symmetric (or symmetric structure) diols include linear C _2-8 alkylene glycol (ethylene glycol, 1,4-butanediol, 1,6-hexanediol, etc.) and symmetric C _6-8 cycloalkanediol ( Examples include at least one diol selected from 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol and the like.

  When the proportion of the symmetric dicarboxylic acid component and the symmetric diol component increases, the crystallinity (or crystallinity) of the photocurable polyester resin increases. On the other hand, when the ratio of the polycarboxylic acid component having an asymmetric structure (including a dicarboxylic acid component) and the polyol component having an asymmetric structure (including a diol component) increases, the crystallinity (or crystallinity) of the photocurable polyester resin increases. descend. Therefore, the proportion of the dicarboxylic acid component having a symmetric structure in the polycarboxylic acid component (including the dicarboxylic acid component) is, for example, 50 to 100 mol%, preferably 70 to 100 mol%, more preferably 85 to 100 mol%. The ratio of the diol component having a symmetrical structure in the polyol component (including the diol component) is, for example, 50 to 100 mol%, preferably 70 to 100 mol%, more preferably 85 to 100 mol. % May be sufficient.

  The reaction between the polyester resin having a functional group and the polymerizable compound is carried out by a conventional method, for example, a thermal polymerization inhibitor (for example, hydroquinone alkyl ether such as hydroquinone or t-butyl hydroquinone) in an inert gas atmosphere. In the presence, an esterification catalyst (metal catalyst, amines, etc.) may be used, usually at a temperature of about 60 to 160 ° C. (for example, 80 to 130 ° C.). If necessary, the reaction may be carried out in the presence of an organic solvent. The ratio of the reactive group of the polymerizable compound to 1 mol of the functional group of the polyester resin is 0.5 to 1.5 mol, preferably 0.7 to 1.3 mol, and more preferably 0.8 to 1. About 2 mol may be sufficient. After completion of the reaction, a photopolymerizable polyester resin that is solid at room temperature can be obtained by removing residual monomers and solvents as necessary.

  The acid value of the photocurable polyester resin is usually about 0.1 to 10 mgKOH / g (for example, 0.3 to 5 mgKOH / g).

  Examples of the photocurable acrylic resin include an acrylic resin having a reactive group (hydroxyl group, carboxyl group, glycidyl group, etc.) and a polymerizable unsaturated compound having a reactive group with respect to the reactive group (for example, a hydroxyl group). Reacts to vinyl phenyl isocyanate, maleic anhydride, maleic acid, (meth) acrylic acid or reactive derivatives thereof (anhydrous (meth) acrylic acid, (meth) acrylic acid chloride, etc.), carboxyl groups Polymerizable groups (α, β-ethylenically unsaturated bonds such as (meth) acryloyl groups) formed by reaction with possible glycidyl (meth) acrylate, (meth) acrylic acid capable of reacting with glycidyl groups, etc.) An acrylic resin having

  The photocurable epoxy (meth) acrylate resin includes, for example, an epoxy (meth) acrylate resin produced by a reaction between an epoxy resin such as a bisphenol A type epoxy resin and (meth) acrylic acid.

  Examples of the photocurable urethane (meth) acrylate resin include a resin produced by a reaction between a urethane oligomer having an isocyanate group and a hydroxyalkyl (meth) acrylate, a resin having a hydroxyl group (the polyester resin, the acrylic resin). ) And a (meth) acrylate having a free isocyanate group (for example, a product of a reaction of a polyisocyanate and a hydroxyalkyl (meth) acrylate) or the like.

  The concentration of the polymerizable group (such as (meth) acryloyl group) in the photocurable resin is usually 200 to 10,000 g / eq (particularly 250 to 8000 g / eq) as a polymerizable unsaturated bond equivalent (molecular weight per polymerizable group). For example, 300 to 7000 g / eq, preferably 350 to 5000 g / eq, and more preferably 400 to 4000 g / eq (particularly 500 to 3000 g / eq). The number average molecular weight of the photocurable resin may be, for example, about 500 to 30000, preferably 700 to 20000, and more preferably about 900 to 15000 (particularly 1000 to 10,000).

  Of the photocurable resins, at least one photocurable resin selected from polyester resins, epoxy resins, and urethane resins and having a polymerizable unsaturated bond is preferable.

  Photocurable resins (noncrystalline and crystalline resins) usually have a glass transition temperature or a heat melting temperature (or melting point). The glass transition temperature (Tg) of the photocurable resin may be, for example, about 40 to 70 ° C, preferably 40 to 65 ° C, and more preferably about 40 to 60 ° C (particularly 40 to 50 ° C).

  The photo-curing resin may be generally composed of an amorphous resin (for example, less than 10% crystallinity) or a crystalline resin (including a semi-crystalline resin) exhibiting the glass transition temperature. In order to improve the coating film performance and the appearance characteristics of the coating film, a non-crystalline resin and a crystalline resin may be combined. The crystallinity of the crystalline resin may be, for example, about 10 to 70%, preferably 15 to 60%, and more preferably about 20 to 50%. The thermal melting temperature (or melting point) of the crystalline resin is usually about 50 to 150 ° C., for example, 55 to 130 ° C., preferably 60 to 110 ° C., more preferably 65 to 100 ° C. (particularly 70 to 90 ° C.). ) Degree.

  The ratio (weight ratio) between the non-crystalline resin and the crystalline resin constituting the photocurable resin is usually about the former / the latter = 50/50 to 99/1, for example, 60/40 to 98/2. It may be 70/30 to 97/3, preferably 75/25 to 96/4 (particularly 80/20 to 95/5).

  The photocurable resin may contain a conventional radical polymerizable diluent in order to adjust the polymerizability, kneadability and the like as long as the photopolymerizable composition can maintain a solid state at room temperature. The polymerizable diluent may be liquid or solid at room temperature (for example, about 10 to 25 ° C.). The ratio (weight ratio) between the photocurable resin and the radical polymerizable diluent may be about the former / the latter = 100/0 to 80/20 (for example, 100/0 to 90/10).

  The photopolymerizable composition of the present invention may contain a polyfunctional polymerizable compound having a plurality of polymerizable groups (α, β-ethylenically unsaturated bonds) as at least a part of the polymerizable diluent. The polyfunctional polymerizable compound can adjust the polymerizability or crosslink density, melting temperature, melt viscosity, and the like of the photopolymerizable composition. Since the polyfunctional polymerizable compound is highly reactive and polyfunctional, the quality of the cured coating film is deteriorated (for example, remaining unreacted polyfunctional polymerizable compound in the cured coating film). In addition, the hardness of the cured coating film can be improved to a high degree. Particularly, the coating film hardness (pencil hardness) is 2 ranks or more (preferably 3 to 8 functions, preferably 4 to 7 functions, preferably 4 to 7 functions, more preferably 5 to 6 functions). Can be improved by 3 ranks or more, for example, pencil hardness F to 2H or 3H. For example, a photopolymerizable composition is melt-coated on a substrate, pre-cured by irradiation with actinic light, then heated and flattened, and further cured by irradiation with actinic light. The hardness (pencil hardness) may be, for example, about H or higher (usually H to 5H, particularly H to 4H), preferably about 2H or higher (usually 2H to 4H). The pencil hardness can be measured according to, for example, JIS K5400 (1990).

  The polyfunctional polymerizable compound is liquid, semi-solid or solid (usually at room temperature (eg, about 10 to 25 ° C.) as long as the photopolymerizable composition can be maintained in the form of a solid (eg, powder). Liquid form). The polyfunctional polymerizable compound often has a lower melting point (or glass transition point) than the photocurable resin, and often lowers the glass transition temperature of the photopolymerizable composition. Usually, compared to solid polyfunctional polymerizable compounds, liquid polyfunctional polymerizable compounds have a large effect of lowering the glass transition temperature of the photopolymerizable composition, and the glass transition temperature and melting of the photopolymerizable composition. In many cases, the temperature (and melt viscosity) is efficiently reduced.

The polyfunctional polymerizable compound has two or more polymerizable groups (photopolymerizable groups) and has two or more functions, for example, 2 to 10 functions, preferably 3 to 8 functions, and more preferably 4 to 6 functions. It may be a degree. Examples of the polymerizable group include (meth) acryloyl group, alkenyl group (C _2-4 alkenyl group such as vinyl group, allyl group, etc.) and the like, and usually at least (meth) acryloyl group (especially acryloyl group). ) In many cases.

  The polyfunctional polymerizable compound may be, for example, urethane (meth) acrylate, epoxy (meth) acrylate, a reaction product of a glycidyl group-containing oligomer or copolymer and (meth) acrylic acid, polyol poly (meth) acrylate, or the like. Good.

  Examples of the urethane (meth) acrylate include a reaction product of an organic polyisocyanate (for example, tolylene diisocyanate, isophorone diisocyanate, etc.) and a hydroxyalkyl (meth) acrylate, a terminal isocyanate oligomer and a hydroxyalkyl (meth) acrylate. A reaction product etc. can be illustrated. The terminal isocyanate oligomer can be produced by a reaction between a polyisocyanate and a polyol (polyester diol, polyether diol, polycarbonate diol, etc.).

  Examples of the epoxy (meth) acrylate include a reaction product of an epoxy compound (such as glycidyl ether of bisphenol A) and (meth) acrylic acid. Examples of the reaction product of a glycidyl group-containing oligomer or copolymer and (meth) acrylic acid include, for example, glycidyl (meth) acrylate and a copolymerized vinyl monomer (acrylic monomers such as n-butyl methacrylate, methyl methacrylate, etc. Examples thereof include a reaction product of a glycidyl group-containing copolymer obtained by copolymerization with (meth) acrylate and the like) and (meth) acrylic acid.

  The polyol poly (meth) acrylate has two or more (meth) acryloyl groups, and all or part of the hydroxyl groups of the polyol may be substituted with (meth) acryloyl groups. It may have a hydroxyl group of about 10 to 10, preferably 4 to 8, more preferably about 4 to 6. The polyol constituting the polyol poly (meth) acrylate is a non-aliphatic polyol (aromatic polyol, heterocyclic polyol, etc.) or an aliphatic polyol [alicyclic polyol, acyclic aliphatic polyol (eg, alkane polyol, alkane). Polyol oligomers and the like)].

Typical polyol poly (meth) acrylates include, for example, aromatic polyol poly (meth) acrylates [for example, C _2-4 alkylene oxide adducts of bisphenols (such as bisphenol A-C _2-4 alkylene oxide adducts). Di (meth) acrylate], heterocyclic polyol poly (meth) acrylate [for example, polyol having an isocyanurate ring [di- or tri (meth) acrylate etc. of tris (2-hydroxyethyl) isocyanurate]], fat Cyclic polyol poly (meth) acrylate [for example, di (meth) acrylate of C _6-10 cycloalkanediol (1,4-cyclohexanedimethanol, etc.), di (meth) acrylate of hydrogenated bisphenol A alkylene oxide adduct, etc. ], Alkane polyol or Examples thereof include poly (meth) acrylates of the oligomer. The poly (meth) acrylate of an alkane polyol or an oligomer thereof includes an alkane polyol or an oligomer thereof and a compound [(C _2-4 alkylene oxide (for example, ethylene oxide), lactone (for example, ε- Poly (meth) acrylates of adducts such as caprolactone, etc.], alkane polyols in which some hydroxyl groups are etherified [alkyl (eg, C _1-12 alkyl) etherification, etc.] or esterified (or acylated). Or the oligomer poly (meth) acrylate is also included.

Examples of the alkane polyol constituting the poly (meth) acrylate of the alkane polyol or its oligomer include, for example, C _2-12 alkane diol, preferably C _2-10 alkane diol, more preferably C _2-8 alkane diol (particularly C _{2 -6} alkanediol) (for example, ethylene glycol, propylene glycol, trimethylene glycol, tetramethylene glycol, 1,3-butanediol, neopentyl glycol, hexanediol, etc.); C _3-12 alkanetriol, preferably C _{3- 10} alkanetriols, more preferably C _3-8 alkanetriols (especially branched C _4-6 alkanetriols) (eg trimethylolpropane, glycerin etc.); C _4-12 alkanetriols (preferably C _4-12 Alkanetetraol, even better Preferably C _4-10 alkanetetraol (particularly branched C _5-8 alkanetetraol) (eg pentaerythritol); C _5-15 alkanepentaol, preferably C _{5-12 alkanepentaol} , Preferred examples include C _5-10 alkanepentaol (particularly branched C _5-8 alkanepentaol) (eg, xylitol), C _{6-18 alkanehexaol} (eg, sorbit), etc. Alkane polyol The oligomer may be, for example, a 2 to 10-mer of an alkane polyol, preferably a 2 to 5 mer, more preferably a 2 to 3 mer, and is composed of a single or two or more polyols. Also good.

  Representative poly (meth) acrylates of alkane polyols or oligomers thereof include, for example, di (meth) acrylates of alkanediol or oligomers thereof (particularly dimers or trimers) [for example, ethylene glycol di (meth) acrylate, propylene glycol di- (Meth) acrylate, 1,4-butanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, di- or triethylene glycol di (meth) acrylate, di Or tripropylene glycol di (meth) acrylate, etc.]; di- or tri (meth) acrylates of alkanetriol or oligomers thereof (particularly dimers or trimers) [for example, trimethylolpropane tri (meth) acrylate] Rate, glycerin di (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, diglycerin tri to tetra (meth) acrylate, triglycerin tri to penta (meth) acrylate, etc.]; alkanetetraol or its oligomer (especially dimer or Trimer) di to hexa (meth) acrylate [for example, pentaerythritol tri to tetra (meth) acrylate, dipentaerythritol tri to hexa (meth) acrylate (manufactured by Nippon Kayaku Co., Ltd., “KARAYAD DPHA”, etc. ), Penta (meth) acrylate of dipentaerythritol monoalkyl ether (manufactured by Nippon Kayaku Co., Ltd., “KARAYAD D-310”, etc.), dipentaerythritol caprolactone adduct Sa (meth) acrylate (manufactured by Nippon Kayaku Co., Ltd., “KARAYAD DCPA-20”, “KARAYAD DCPA-30”, “KARAYAD DCPA-60”, “KARAYAD DCPA-120”, etc.), alkanepentaol or an oligomer thereof Examples thereof include dimer or hexa (meth) acrylate (particularly dimer or trimer).

The polyfunctional polymerizable compound is, for example, alkanediol, alkanetriol (monomer, dimer or trimer) or alkanetetraol in view of the melting temperature and viscosity of the photopolymerizable composition, the surface hardness and appearance of the cured coating film, etc. Poly (meth) acrylates of polyols such as (monomer, dimer or trimer) may be used. Among these, alkane polyol oligomer poly (meth) acrylates often have an ether bond, and thus can effectively impart high flexibility to a cured coating film. Examples of the polyol having an ether bond include, for example, alkanetriol dimer or trimer di to penta (meth) acrylate, alkanetetraol dimer or trimer di to hexa (meth) acrylate [preferably C _3-10 alkanetriol. or C _4-10 such as tri to hexa (meth) acrylate of an alkane tetraol dimer (especially C _4-10 alkane tetraols dimer)], and others.

  Polyfunctional polymerizable compounds can be used alone or in combination of two or more.

  The concentration of the polymerizable group of the polyfunctional polymerizable compound may be usually larger than the concentration of the polymerizable group of the photocurable resin, and is, for example, 30 to 300 g / eq, preferably 50 as the polymerizable unsaturated bond equivalent. It may be about 200 g / eq, more preferably about 70 to 150 g / eq.

  The proportion of the polyfunctional polymerizable compound depends on the type of photocurable resin and the type and shape of the polyfunctional polymerizable compound (liquid, semi-solid, solid), but usually the photopolymerizable composition is at room temperature ( For example, it can be selected within a range that can maintain a solid (for example, granular) form at 10 to 25 ° C., and is usually about 0.5 to 35 parts by weight with respect to 100 parts by weight of the photocurable resin. 1 to 30 parts by weight, preferably 3 to 25 parts by weight, more preferably about 5 to 20 parts by weight (particularly 7 to 15 parts by weight).

  The photopolymerizable composition may usually contain a photopolymerization initiator. A photoinitiator can be selected according to the kind of actinic light, and may form an ultraviolet curable composition.

  Examples of the photopolymerization initiator include ketone compounds, phosphine compounds, sulfide compounds (dibutyl sulfide, diphenyl disulfide, dibenzyl sulfide, decylphenyl sulfide, tetramethylthiuram monosulfide, etc.). Of these photopolymerization initiators, ketone compounds and phosphine compounds are preferred.

  Examples of ketone compounds include acetophenone compounds (acetophenone diethyl ketal, diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl. -Phenyl ketone, etc.), benzophenone compounds [benzophenone, 2,4,6-trimethylbenzophenone, 4,4'-dimethoxybenzophenone, 4-phenylbenzophenone, 3,3'-dimethyl-4-methoxybenzophenone, 4,4 ' -Diaminobenzophenone, 4-N, N-dimethylamino-4'-methoxybenzophenone, methyl benzoylbenzoate, 4-benzoyl-4'-methyldiphenyl sulfide, (4-benzoylbenzyl) trimethylan Nium chloride, bis (4-dialkylaminophenyl) ketone, etc.], benzoin compounds (benzoin derivatives such as benzoin and benzoin ethyl ether), benzyl compounds (benzyl, benzylmethyl ketal, etc.), anthraquinone compounds (anthraquinone, 2 -Methylanthraquinone, 2-ethylanthraquinone, etc.), thioxanthone compounds (isopropylthioxanthone, diethylthioxanthone, etc.), morpholine compounds [2-methyl-2-morpholino (4-thiomethylphenyl) propan-1-one, 2-benzyl 2-dimethylamino-1- (4-morpholinophenyl) -butane, 3,6-bis (2-morpholinoisobutyl) -9-butylcarbazole and the like].

  Examples of the phosphine compound include 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, bis -(2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide (BAPO), bis (2,4,6-trimethylbenzoyl) methylphosphine oxide, bis (2,4,6-trimethylbenzoyl) Examples thereof include ethylphosphine oxide and bis (2,4,6-trimethylbenzoyl) n-butylphosphine oxide.

  A photoinitiator can be used individually or in combination of 2 or more types. For example, a ketone compound and a phosphine compound may be used in combination.

  The proportion of the photopolymerization initiator is, for example, 0.1 to 10 parts by weight, preferably 0.15 to 8 parts by weight, and more preferably 0.2 to 6 parts by weight (100 parts by weight). In particular, it may be about 0.3 to 5 parts by weight.

  The photopolymerizable composition contains a photopolymerization initiator and a sensitizer, for example, tertiary amines (dialkylaminobenzoic acid or its ester, acridine, etc.), coumarins [3- (2-benzothiazolyl) -7- (Diethylamino) coumarin, etc.], quinolines [2- (2- (4-dimethylaminophenyl) ethenyl) quinoline, etc.], quinones (benzoquinone, anthraquinone, etc.), pyrenes (1-nitropyrene, etc.), aromatic hydrocarbons (Such as acenaphthene) may be included.

  The photopolymerizable composition may form a paint capable of forming a clear coating (for example, a solid paint such as a powder paint), or a matte paint (for example, a solid paint such as a matte powder paint). It may be formed.

  In many cases, the photopolymerizable composition usually contains a filler. This filler is usually a powder, and may be, for example, an organic powder or an inorganic powder. The filler includes a pigment in addition to a general additive called a filler, and may or may not have hiding properties. The filler may have colorability like a color pigment, but may not have colorability like an extender pigment, and has a matte function (such as a gloss on the coating surface) like a matting agent. May have a function of adjusting), but may not have a matte function.

  The filler may be an inorganic filler or an organic filler. Examples of the filler include inorganic fillers such as mica, kaolin clay, bentonite, and talc, and organic fillers such as resin particles (crosslinked resin particles such as crosslinked acrylic resin particles and crosslinked polystyrene resin particles). The A filler can be used individually or in combination of 2 or more types.

Examples of the pigment include extender pigments [metal oxides (silica, alumina, etc.), metal hydroxides (aluminum hydroxide, etc.), metal carbonates (calcium carbonate, magnesium carbonate, etc.), metal sulfates [barium sulfate (especially Barite powder obtained by grinding barite), metal silicates (calcium silicate, aluminum silicate, etc.), glass (quartz glass, etc.); white pigments [titanium dioxide, zinc oxide, alumina white, etc.] Aluminum oxide, magnesium silicate, lithopone (ZnS + BaSO _4, etc.)], black pigment (carbon black, etc.), red pigment (brown, lead red, molybdenum red, cadmium red, etc.), yellow pigment (yellow iron oxide, yellow lead, risurge) , Cadmium yellow, Chrome yellow, etc.), Orange pigment (Molybdate orange, etc.) , Inorganic pigments such as blue pigments (such as bitumen and ultramarine), green pigments (such as chrome green), purple pigments (such as manganese violet), metal powder pigments (such as aluminum powder pigments); yellow-red pigments [azo pigments (pigments) Yellow, pigment orange, pigment red, hansa yellow, etc.), quinacridone pigments (such as quinacridone red), perylene pigments (such as perylene maroon)], blue-green pigments [phthalocyanine pigments (such as phthalocyanine blue, phthalocyanine green)] Organic pigments such as are exemplified.

  Pigments are pigments with special functions, such as anti-corrosion pigments [metal chromate (zinc chromate, strontium chromate, etc.), lead compounds (lead red, lead suboxide, basic lead chromate, cyanamide lead, calcium leadate, etc.) ), Metal phosphates (such as zinc phosphate, aluminum phosphate, potassium phosphate), metal zinc powder, glass flake powder, etc.], antifouling pigments (such as cuprous oxide), fluorescent pigments, pearl pigments, etc. Also good. The pigments can be used alone or in combination of two or more.

  Examples of the filler having a matting function (matting agent) include metal oxides (silica, alumina, etc.), metal hydroxides (aluminum hydroxide, etc.), metal carbonates (calcium carbonate, magnesium carbonate, etc.), Examples thereof include colloidal silicic acid and glass. Matting agents can be used alone or in combination of two or more.

  The average particle diameter of the filler other than the matting agent is usually about 0.001 to 5 μm (for example, 0.005 to 3 μm), although it depends on the type of the filler, preferably 0.01. It may be about 1 μm (for example, 0.05 to 0.5 μm), more preferably about 0.1 to 0.3 μm. The oil absorption amount of the filler other than the matting agent is usually about 10 to 60 ml / 100 g, for example, about 15 to 55 ml / 100 g. Oil absorption can be measured according to JIS K5101 using linseed oil.

  The average particle size of the matting agent is usually about 0.1 to 12 μm, for example, 0.5 to 10 μm, preferably 1 to 8 μm, and more preferably about 2 to 7 μm. The oil absorption amount of the matting agent is usually about 50 to 200 ml / 100 g, for example, 60 to 170 ml / 100 g, preferably 70 to 150 ml / 100 g (for example, about 75 to 120 ml / 100 g).

  A filler can be used individually or in combination of 2 or more types. For example, a matting agent and a filler other than the matting agent can be used in combination. The usage-amount of a filler can be normally selected from about 0-300 weight part (for example, 10-300 weight part) with respect to 100 weight part of photocurable resins, Preferably it is 20-250 weight part (for example, 30). ˜200 parts by weight), more preferably about 40 to 150 parts by weight (particularly 50 to 100 parts by weight).

  When the matting agent is used, the amount of the matting agent is usually 200 parts by weight or less (for example, about 0.5 to 200 parts by weight) with respect to 100 parts by weight of the photocurable resin, preferably 5 to 180 parts by weight (for example, 15 to 150 parts by weight), more preferably 30 to 120 parts by weight (for example, 40 to 110 parts by weight), particularly about 50 to 100 parts by weight (for example, 60 to 90 parts by weight). There may be.

  When a matting agent and a filler other than a matting agent are used in combination, usually the weight ratio can be selected from the former / the latter = 1/99 to 99/1, for example, 5/95 to 95/5, Preferably, it may be about 10/90 to 90/10, more preferably about 15/85 to 85/15 (particularly 20/80 to 80/20).

  In the present invention, even when a single photopolymerizable composition is used, the gloss of the cured coating film can be adjusted by a simple operation of adjusting the irradiation energy of actinic rays in the preliminary curing step. In particular, the gloss of the coating film can be adjusted in a wide range by adjusting the content of the filler and the irradiation energy of actinic rays in the preliminary curing step.

  The photopolymerizable composition includes various additives such as waxes, surface conditioners or leveling agents (acrylic leveling agents, vinyl leveling agents, silicone leveling agents, fluorine leveling agents, etc.), dispersants (nonions). Surfactants, surfactants such as anionic surfactants, polymer-type dispersants that may be nonionic or anionic), stabilizers (such as UV absorbers, antioxidants, thermal stabilizers), plasticizers Further, it may contain a viscosity modifier, a flame retardant, a charging agent, an antistatic agent and the like. The use amount of these additives may be about 0.1 to 5 parts by weight, preferably about 0.2 to 3 parts by weight with respect to 100 parts by weight of the photocurable resin.

  The form of the photopolymerizable composition is not particularly limited, and is, for example, non-fibrous (spherical, ellipsoidal, polygonal, amorphous, etc.), fibrous (needle, short fiber, long fiber, etc.). For example, it may be a granular material (powdered, granular, chip-shaped, pellet-shaped, block-shaped, flake-shaped, etc.), and is usually a non-fibrous granular material (particularly chip-shaped or block-shaped). Shaped granular material).

  The maximum particle size of the photopolymerizable composition may be, for example, 30 mm or less, preferably 20 mm or less, and more preferably about 10 mm or less. The maximum particle size of the photopolymerizable composition may usually be about 0.005 mm or more. The volume average particle diameter of the photopolymerizable composition is not particularly limited, and is usually about 0.005 to 20 mm, for example, 0.01 to 15 mm, preferably 0.05 to 10 mm, and more preferably 0.1. About 8 mm (especially 0.5-5 mm) may be sufficient.

  For example, when melt-coating a photopolymerizable composition, even if the photopolymerizable composition (for example, powder particles such as chips and blocks) is fused (blocked), it does not cause a serious problem. Therefore, although not necessarily required, a granular blocking inhibitor can be used as necessary to prevent blocking of the photopolymerizable composition. The anti-blocking agent is usually composed of organic or inorganic fine particles (particularly inorganic fine particles). Examples of the anti-blocking agent include metal oxides [silica, alumina, magnesia, titanium oxide, iron oxide, zinc oxide, etc.], metal carbonates (calcium carbonate, magnesium carbonate, etc.), metal sulfates (calcium sulfate, barium sulfate). Etc.), metal silicates (calcium silicate, aluminum silicate, etc.), silicic acid (hydrous silicic acid) and the like. Of these inorganic fine particles, silicon-containing inorganic fine particles, for example, fine particles such as silica, metal silicate, and silicic acid [usually silica fine particles (particularly anhydrous silica fine particles) and the like] are often used. An antiblocking agent can be used individually or in combination of 2 or more types. Among such anti-blocking agents, anhydrous silica fine particles are available from Nippon Aerosil Co., Ltd. under the trade names “Aerosil R972”, “Aerosil R805”, “Aerosil R812S” and the like.

  The antiblocking agent may be hydrophilic or hydrophobic. A preferred anti-blocking agent has a hydrophobic surface. The surface of the fine particles constituting the antiblocking agent is, for example, silicone oil (such as dimethyl silicone oil), alkylsilane (such as octylsilane), silane coupling agent (such as a silane coupling agent having an alkylsilyl group such as a trimethylsilyl group), etc. Can be made hydrophobic.

  The average particle diameter of the fine particles (primary particles) constituting the antiblocking agent is usually 1 to 100 nm, for example, about 3 to 90 nm, preferably 5 to 80 nm, more preferably 8 to 70 nm (particularly 10 to 50 nm). It may be. The fine particles constituting the anti-blocking agent have a small bulk density and are usually about 20 to 200 g / L, for example, 25 to 180 g / L, preferably 30 to 150 g / L, more preferably 35 to 130 g / L ( In particular, it may be about 40 to 100 g / L).

  The amount of the antiblocking agent used is, for example, 0.01 to 1 part by weight, preferably 0.05 to 0.8 part by weight, and more preferably 0.08 to 0 part per 100 parts by weight of the photopolymerizable composition. It may be about 5 parts by weight (particularly 0.1 to 0.3 parts by weight). An antiblocking agent may be added to the granular material of the photopolymerizable composition. By adding an anti-blocking agent, it is possible to effectively prevent blocking of the particles of the photopolymerizable composition and improve storage stability. The anti-blocking agent may be released from the photopolymerizable composition and may be interposed between the photopolymerizable composition powder particles, and all or part of the antiblocking agent may be present on the surface of the photopolymerizable composition powder particles. Bonding (or fixing) may be performed by embedding or adhesion.

[Method for producing photopolymerizable composition]
The photopolymerizable composition (particularly, the granular material of the photopolymerizable composition) includes, for example, a photocurable resin, a photopolymerization initiator, and [additives as necessary (for example, polymerizable diluent, filler). Etc.) and] are melt-kneaded, cooled and solidified, pulverized, and classified if necessary. You may mix an antiblocking agent with the photopolymerizable composition classified into the predetermined size. However, in many cases, a mixture containing a photocurable resin and a photopolymerization initiator is melt-kneaded, cooled and solidified, an antiblocking agent is added to the obtained solidified product, pulverized, and classified as necessary. When the solidified product of the photopolymerizable composition is pulverized in the presence of an anti-blocking agent, the anti-blocking agent is fixed to the surface of the resulting photopolymerizable composition, or the particles of the photopolymerizable composition. The storage stability or blocking resistance of the body can be improved.

  The melt kneading of the mixture containing the photocurable resin and the photopolymerization initiator (and other additives as necessary) is performed while suppressing polymerization or curing of the photocurable resin. , Cooled and solidified into a granular (eg, pellet) form. Melt kneading is a conventional method, for example, each component is dry-mixed with a mixer (Henschel mixer, ribbon mixer, etc.) and melted with a melt kneader (single or twin screw extruder, Banbury mixer, kneader, mixing roll, etc.). It can be performed by kneading. The melt kneading temperature may be a temperature capable of suppressing polymerization of the photocurable resin, and is usually about 60 to 160 ° C., for example, 65 to 150 ° C., preferably 70 to 130 ° C., more preferably 75. It may be about ~ 120 ° C (particularly 80 to 100 ° C).

  If necessary, the pulverization step after cooling and solidification may be repeated. In the pulverization step, a conventional pulverizer such as an atomizer can be used. When a resin having a low glass transition temperature or melting point is used as the photocurable resin, the solidified product is preferably pulverized under cooling (for example, cooling with cold air, dry ice, liquefied nitrogen, etc.). The cooling temperature is, for example, about 40 ° C. or less (for example, 0 to 40 ° C.), preferably about 30 ° C. or less (for example, 3 to 30 ° C.), and more preferably about 20 ° C. or less (for example, 5 to 20 ° C.). Good. If necessary, after pulverization, classification may be performed using a sieve or a classifier in order to obtain a granular material of a predetermined size.

[Coating process]
The coating film (uncured coating film) formed of the photopolymerizable composition is, for example, (1) a substrate heated to a temperature higher than the melting temperature of the photopolymerizable composition, for example, using a spray gun. A method of spraying and applying powder particles of a polymerizable composition (powder spraying method), (2) a substrate preheated to a temperature higher than the melting temperature of the photopolymerizable composition, Method of dipping in a fluidized bed of powder and melt-coating (fluid dipping method), (3) Method of sucking and adhering powder of photopolymerizable composition to substrate using static electricity (powder static (4) a method of melt-coating a photopolymerizable composition on a substrate (melt coating method), or the like. Among these methods, the melt coating method is preferable from the viewpoint of the coating efficiency of the photopolymerizable composition.

  The substrate may be, for example, an organic substrate or an inorganic substrate, and may be a non-porous substrate or a porous substrate. Examples of the organic substrate include nonporous substrates such as nonporous plastics; porous substrates such as wood materials, porous plastics, paper, and fabrics (woven fabrics and nonwoven fabrics). Examples of the wood material include natural wood and synthetic wood [for example, MDF board (medium fiber board), particle board (PB), veneer board, etc.]. Examples of the inorganic base material include non-porous base materials such as ceramic, glass, and metal (steel plate, aluminum, stainless steel, etc.); and porous base materials such as concrete panels, gypsum boards, and porous metals. Examples of the porous metal include magnesium alloy castings, aluminum die casts, aluminum sprayed iron plates, castings, zinc sprayed iron plates (metallicons), and the like. The substrate can be selected in consideration of the method for forming a coating film of the photopolymerizable composition. The substrate may be a single substrate or two or more composite substrates.

  In the melt coating method, the substrate does not necessarily have to be heated (preheated), but from the viewpoint of the appearance of the formed coating film, the photopolymerizable composition is melt coated on the heated substrate. May be. The heating temperature may be, for example, a temperature lower or higher than the melting temperature of the photopolymerizable composition. The heating temperature is usually about 30 to 130 ° C., for example, 35 to 120 ° C., preferably 40 to 110 ° C., and more preferably about 45 to 100 ° C. (particularly 50 to 90 ° C.). If the heating temperature is low, the coating film appearance may be adversely affected. If the heating temperature is too high, the substrate may be deformed. The substrate can be heated using various heating means (for example, a heater such as a far-infrared heater, a near-infrared heater, and a hot air heater).

  The photopolymerizable composition is brought to its melting temperature [usually about 50 to 200 ° C., for example 60 to 180 ° C., preferably 70 to 160 ° C., more preferably about 80 to 150 ° C. (especially about 90 to 140 ° C.)]. It can be melt coated by heating. Examples of the melt coating method include a roll coater method and a thermal spraying method. From the viewpoint of mass productivity, a roll coater method using a hot roll is preferred.

  In FIG. 1, the schematic for demonstrating the application | coating state by a roll coater method is shown. In the roll coater method, a pair of doctor rolls 2 for controlling the supply amount of the photopolymerizable composition 4 and a coater roll 1 for applying the molten photopolymerizable composition 4 to the substrate 3. A roll coater having the following rolls is used. The coater roll 1 and the doctor roll 2 (especially the surface of each roll) may be made of metal or nonmetal (for example, rubber such as heat-resistant silicone rubber). The coater roll 1 and the doctor roll 2 may be the same or different from each other. Using the coater roll 1 and the doctor roll 2, a melted photopolymerizable composition coating film (uncured) is formed on the porous substrate 3 which is conveyed in a predetermined direction at a predetermined speed by a conveying means 5 such as a conveyor. Coating film) can be formed.

  In the case of the roll coater method, the heating temperature of the coater roll and doctor roll is a temperature at which the photopolymerizable composition can be maintained in a molten state (melting temperature), usually about 50 to 200 ° C, preferably 60 to 180 ° C, Preferably, it may be about 70 to 160 ° C, more preferably about 80 to 150 ° C (particularly 90 to 140 ° C). When the heating temperature of each roll is low, the melt viscosity of the photopolymerizable composition is increased, and the leveling property of the coating film tends to decrease. When the heating temperature of each roll is too high, the stability of the photopolymerizable composition tends to decrease. The coater roll and doctor roll can be heated by, for example, a method in which an electric heater is incorporated in each roll and heating, a method in which heated oil is circulated in each roll, and the like.

  In a pair of rolls composed of a coater roll and a doctor roll, the doctor roll may be rotated, but without rotating the doctor roll, the coater roll is rotated (for example, rotated in the conveyance direction of the substrate), By melt coating, a coating film with an appropriate coating amount and good appearance can be formed.

The coating amount of the photopolymerizable composition with respect to the substrate is not particularly limited, and can usually be selected from a range of about 10 to 300 g / m ² , for example, 20 to 250 g / m ² , preferably 40 to 200 g / m ^2. More preferably, it may be about 60 to 180 g / m ² (particularly 80 to 150 g / m ² ). The coating amount may be controlled by, for example, the distance between the coater roll and the doctor roll, the rotation speed, or the like. The distance between the coater roll and the doctor roll is usually about 2500 μm or less, and may be, for example, about 10 to 2000 μm, preferably 50 to 1500 μm, and more preferably about 100 to 1000 μm (particularly 200 to 500 μm). For example, when the surface of at least one of the coater roll and the doctor roll is made of an elastic material (such as rubber), the coater roll and the doctor roll may be in contact with each other, the doctor roll is pressed against the coater roll, The roll surface made of at least one elastic material may be in a depressed state. The coating amount may be controlled by the peripheral speed V ₁ of the coater roll. That is, the coating amount can be increased by increasing the peripheral speed V ₁ of the coater roll. The peripheral speed V ₁ of the coater roll can be selected according to the flow characteristics such as the melt viscosity of the photopolymerizable composition, and is usually about 1 to 30 m / min, for example, 2 to 25 m / min, preferably 3 to 3 m / min. It may be about 20 m / min, more preferably about 5 to 15 m / min (particularly 7 to 13 m / min). The coating amount may be controlled by the difference (V ₂ −V ₁ ) between the coater roll peripheral speed V ₁ and the conveyor speed V ₂ for conveying the substrate. In other words, than the coater roll peripheral speed V _1, may be increased conveyor speed V _2, based on the conveyor speed V _2, the higher the coater roll peripheral speed V _1, can increase the coating amount. Conveyor speed V ₂ is not particularly limited, usually about 5～60M / min, for example 10～55M / min, preferably 15 to 50 m / min, more preferably 20～45M / min (especially 25~40m / Min). The difference (V ₂ −V ₁ ) between the coater roll circumferential speed V ₁ and the conveyor speed V ₂ is, for example, about 5 to 30 m / min, preferably about 10 to 25 m / min, and more preferably about 15 to 20 m / min. May be.

  The coating speed of the photopolymerizable composition on the substrate is not particularly limited and may correspond to the conveyor speed, and is usually about 5 to 60 m / min, for example, 10 to 55 m / min, preferably 15 to 50 m. / Min, more preferably 20 to 45 m / min (especially 25 to 40 m / min).

[Pre-curing step-heating step-curing step]
In the present invention, an uncured coating film (such as a melted coating film or a heated coating film) is precured (precuring process), then heated (heating process), and the coated film is further cured (curing process). ). The cycle composed of the preliminary curing step, the heating step, or the preliminary curing step and the heating step may be repeated a plurality of times.

  Pre-curing and curing after heating are performed by irradiating an uncured coating film or a heated coating film with actinic rays. The active light may be, for example, gamma rays, X-rays, ultraviolet rays, visible rays, etc., but is usually ultraviolet rays. For the irradiation of ultraviolet rays, for example, an ultraviolet irradiation lamp (high pressure mercury lamp, metal halide lamp, xenon lamp, etc.) can be used. The wavelength range of ultraviolet rays may be, for example, about 270 to 460 nm, preferably 280 to 455 nm, and more preferably about 290 to 450 nm.

  The gloss of the cured coating film (cured coating film) can be adjusted by the actinic ray irradiation energy in the preliminary curing step. That is, generally, the degree of curing of the coating film can be adjusted by the irradiation energy of actinic rays. Usually, when the degree of pre-curing is increased, the improvement of the gloss of the coating film due to the heating process is suppressed, and a cured coating film with a low gloss can be formed. Therefore, the gloss (matte level) is adjusted as necessary. A matte coating can be formed. The actinic ray irradiation energy (unit: J) corresponds to the product of the actinic ray irradiation intensity [wattage (unit: J / s)] and the irradiation time (unit: s). For example, the irradiation energy of ultraviolet rays (irradiation energy per unit area) can be measured by, for example, “UVR-T1” manufactured by TOPCOM Corporation.

  When the irradiation energy of actinic rays in the preliminary curing step is G1 and the irradiation energy of actinic rays in the curing step is G2, the cured coating film having a lower surface gloss as the ratio of G1 to G2 (G1 / G2) is increased. (For example, a more highly matted cured coating film) can be formed. The ratio of G1 / G2 is usually about 1/99 to 30/70, with the total amount of G1 and G2 (G1 + G2) being 100, for example, 2/98 to 25/75, preferably 3/97 to It may be about 20/80, more preferably about 4/96 to 15/85 (particularly 5/95 to 10/90).

The value of irradiation energy (G1) of actinic rays (for example, ultraviolet rays) in the preliminary curing step (the total amount when the preliminary curing step is repeated a plurality of times) is usually about 1 to 1000 mJ / cm ² per unit area of the coating film. For example, it may be adjusted within a range of about 5 to 800 mJ / cm ² , preferably 10 to 500 mJ / cm ² , more preferably 30 to 300 mJ / cm ² (particularly 50 to 200 mJ / cm ² ). Moreover, the value of irradiation energy (G2) of actinic rays (for example, ultraviolet rays) in the curing step is usually about 100 to 5000 mJ / cm ² per unit area of the coating film, for example, 200 to 4000 mJ / cm ² , Preferably, it may be about 300 to 3000 mJ / cm ² , more preferably about 400 to 2500 mJ / cm ² (particularly 500 to 2000 mJ / cm ² ).

  In the heating step, the pre-cured coating film may be usually heated to a temperature higher than the glass transition temperature (or melting temperature) of the photopolymerizable composition, and in the heating step, the pre-cured coating film is flattened. (Leveling) may be used. Although heating temperature is based also on the kind of photopolymerizable composition, it is about 50-160 degreeC normally, for example, 55-150 degreeC, Preferably it is 60-140 degreeC, More preferably, it is 70-130 degreeC (especially 80-130 degreeC). (About 120 degreeC) may be sufficient. The heating time is usually about 1 second to 10 minutes, for example, 3 seconds to 9 minutes, preferably 5 seconds to 8 minutes, more preferably 7 seconds to 7 minutes (particularly 10 seconds to 5 minutes). May be. As a heating source, for example, an infrared irradiation furnace equipped with an infrared (IR) irradiation lamp, a heating furnace such as a hot air drying furnace can be used. A method using an infrared irradiation furnace (for example, an infrared irradiation furnace having a wavelength of about 0.7 to 20 μm) or a method using a combination of the infrared irradiation furnace and a hot air drying furnace is preferable.

  The surface glossiness of the cured coating film can usually be adjusted within a range of about 0.1 to 85, for example, 0.5 to 80, preferably 1 to 75, more preferably 1.5 to 70 (particularly 2 to 2). 65) or so. The surface glossiness of the coating film can be measured under the condition of an incident angle of 60 ° based on, for example, JIS K5600-4-7 (2004).

  The coating film forming method of the present invention is useful for forming a cured coating film from a photopolymerizable composition that is solid or viscous at room temperature (for example, a powder coating material), and in particular, the surface gloss of the cured coating film. And is useful for forming a cured coating film having a desired gloss. The present invention is suitable for manufacturing, for example, a painted panel (for example, a building material panel).

  EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example and a comparative example, this invention is not limited to these Examples.

[Manufacture of powder coatings]
Powder coatings A to E were produced according to the following procedure. Table 1 shows the coating compositions of the powder coatings A to E.
(Powder paint A)
UV curable polyester resin (Daicel UCB Co., Ltd., Uvecoat 3001, Tg = 44 ° C.) 100 parts by weight, semi-crystalline resin (Daicel UCB Co., Ltd., Uvecoat 9010) 10 parts by weight, acrylate monomer [Nippon Kayaku Co., Ltd., Karayad DPHA (dipentaerythritol hexaacrylate)], photopolymerization initiator (Ciba Specialty Chemicals Co., Ltd., Irugacure 819) 1 part by weight, polymerization initiator (Ciba Specialty Chemicals Co., Ltd.) 1 part by weight, Irugacure 2959), matting agent [manufactured by Tatsumori Co., Ltd., Furex E-2 (amorphous high purity fused silica glass filler), average particle size 7 μm], 70 parts by weight, titanium oxide (white pigment) ) 20 parts by weight and 1 part by weight of a surface conditioner (manufactured by SOLUTIA, MODAFLOW POWDER M-2000) were dry mixed with a Henschel mixer for 1 minute, then It was melt-kneaded with a rudder and solidified by cooling. The obtained solidified product was pulverized with a crusher at 5 to 20 ° C. to obtain a chip-like matte powder coating material (powder coating material A).
(Powder paint B)
Chip-like matte in the same manner as powder coating A, except that no photopolymerization initiator (Ciba Specialty Chemicals Co., Ltd., Irugacure 819) was used and the amount of matting agent used was 40 parts by weight. A powder coating material (powder coating material B) was obtained.
(Powder paint C)
A chip-like matte powder coating (powder coating C) was obtained in the same manner as the powder coating A except that the amount of the matting agent used was 20 parts by weight.
(Powder paint D)
A chip-like matte powder coating (powder coating D) was obtained in the same manner as the powder coating A except that the amount of the matting agent (Furex E-2) was 1 part by weight.
(Powder paint E)
A chip-like matte powder coating (powder coating E) was obtained in the same manner as the powder coating A except that the amount of the matting agent used was 40 parts by weight.
(Powder paint F)
Chip-like matte powder paint (powder) in the same manner as powder paint A except that 70 parts by weight of barium sulfate (matte agent) was used instead of 70 parts by weight of matte agent (Furex E-2) Paint F) was obtained.

Example 1
Using a roll coater having a pair of rolls composed of a coater roll 1 and a doctor roll 2 shown in FIG. 1, the chip-shaped powder coating material (powder coating material A) 4 is heated to 130 ° C. and heated to 50 ° C. The pre-heated MDF plate (base material) 3 was melt coated. In this step, the MDF plate 3 is transported at a conveyor speed of 30 m / min using the conveyor 5 as a conveying means, and the coater roll 1 is rotated at a peripheral speed of 10 m / min without rotating the doctor roll 2. Rotated in the transport direction.

Using a high-pressure mercury lamp (wavelength 280 to 450 nm) to the uncured coating film of the powder coating A melt-coated on the MDF plate, UV light is irradiated until the irradiation energy reaches 100 mJ / cm ² or more. Cured (precuring step). Subsequently, the pre-cured coating film was flattened by heating so that the surface temperature became 100 to 120 ° C. in about 3 minutes using a mid-wavelength infrared irradiation furnace (wavelength 1 to 10 μm) (heating step) ). Thereafter, the heated coating film was cured by irradiation with ultraviolet rays for 10 seconds to 3 minutes using a high-pressure mercury lamp (wavelength 280 to 450 nm) (curing step). Table 2 shows the ultraviolet irradiation energy (G1) in the preliminary curing step and the ultraviolet irradiation energy (G2) in the curing step. The irradiation energy of ultraviolet rays in the preliminary curing step and the curing step was set to 1500 mJ / cm ^{2 in} total (G1 + G2). The irradiation energy of ultraviolet rays was measured using “UVR-T1” manufactured by TOPCOM.

Examples 2 and 3
The irradiation energy (G1) of ultraviolet rays in the preliminary curing step was the same as that of Example 1 except that it was 90 mJ / cm ² or more (Example 2) or 80 mJ / cm ² or more (Example 3).

Reference example 1
The procedure was the same as in Example 1 except that no precuring was performed.

Reference example 2
The order of the pre-curing step-heating step-curing step was the same as in Example 1 except that the heating step-pre-curing step-curing step was changed.

Examples 4-8
Instead of powder coating A, powder coating B (Example 4), powder coating C (Example 5), powder coating D (Example 6), powder coating E (Example 7) or Powder coating F (Example 8) was used, and Example 7 was carried out in the same manner as Example 1 except that the irradiation energy (G1) of ultraviolet rays in the preliminary curing step was set to 80 mJ / cm ² or more.

[Evaluation of coating film]
Each test was done in the following procedures for the cured coating films formed in Examples 1 to 8 and Reference Examples 1 and 2. The results are shown in Table 2.
(Surface gloss)
The surface glossiness of the cured coating film is measured under the condition of an incident angle of 60 ° based on JIS K5600-4-7 (2004) “Specular Glossiness”.
(Adhesiveness)
The adhesion of the cured coating film to the substrate is tested under the condition of a cross cut width of 2 mm based on JIS K5600-5-6 (cross cut method) and evaluated according to the following criteria.
Classification 0: The edge of the cut is completely smooth, and there is no peeling to the eyes of any lattice.
Classification 1: Small peeling of the coating film at the intersection of cuts. It is clearly not more than 5% that the crosscut is affected.
Classification 2: The coating is peeled along the edge of the cut and / or at the intersection. The cross-cut part is clearly affected by more than 5% but not more than 15%.
Classification 3: The coating film is partially or completely peeled along the edge of the cut, and / or various parts of the eye are partially or completely peeled off. The cross-cut portion is clearly affected by more than 15% but not more than 35%.
Classification 4: The coating film is partially or completely peeled along the edge of the cut, and / or some eyes are partially or completely peeled off. It is clearly not more than 35% that the cross-cut is affected.
Category 5: When the degree of peeling exceeds Category 4.
(Scratch hardness)
The scratch hardness of the cured coating film is tested based on JIS K5600-5-4 (pencil scratch method).
(Solvent resistance)
The gauze soaked with xylene is allowed to stand for 2 hours on the cured coating, and the cured coating is checked for changes (abnormalities) such as blistering, peeling, and glossiness.

  In Table 2, the comparison with Reference Examples 1 and 2 shows that in Example 1, the surface gloss of the cured coating film is low due to the pre-curing before heating. From Examples 1 to 3, it is understood that the surface gloss of the cured coating film is lower as the ultraviolet irradiation energy (G1) in the preliminary curing is larger. From Examples 1 and 4, it can be seen that the photopolymerization initiator also affects the surface gloss of the cured coating film, but has a smaller effect than the preliminary curing (Examples 1 to 3). From Examples 1 and 5-7, the amount of matting agent also affects the surface gloss of the cured coating, but even if the amount of matting agent is reduced, the surface gloss of the cured coating does not necessarily increase. Therefore, it can be seen that it is difficult to adjust the surface gloss of the cured coating film depending on the amount of the matting agent. From Examples 1 and 8, it can be seen that the type of matting agent also affects the surface gloss of the cured coating film, but the effect is smaller than that of preliminary curing (Examples 1 to 3).

FIG. 1 is a schematic view for explaining a coating state by a roll coater method used in an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Coater roll 2 ... Doctor roll 3 ... Base material (MDF board)
4 ... Photopolymerizable composition (matte powder coating)
5 ... Conveyor

Claims (11)

  The coating film formed of a photopolymerizable composition that is solid or viscous at room temperature is irradiated with actinic rays to be partially cured, then the coating film is heated, and further, the actinic rays are applied to the heated coating film Coating film forming method of irradiating and curing.   The coating film forming method according to claim 1, wherein the viscosity of the photopolymerizable composition is 200 Pa · s or more at 25 ° C.   The coating film forming method according to claim 1, wherein the partially cured coating film is flattened by heating.   The coating film forming method according to claim 1, wherein the photopolymerizable composition contains a filler.   The coating film forming method according to claim 4, wherein the amount of the filler used is 10 to 300 parts by weight with respect to 100 parts by weight of the photocurable resin constituting the photopolymerizable composition.   The method for forming a coating film according to claim 4, wherein the filler comprises at least a matting agent.   The coating film forming method according to claim 6, wherein the amount of the matting agent used is 30 to 120 parts by weight with respect to 100 parts by weight of the photocurable resin constituting the photopolymerizable composition.   The coating film formation method of Claim 1 which irradiates an actinic ray to the coating film formed by the melt coating of the photopolymerizable composition.   The coating film forming method according to claim 1, wherein the actinic ray is ultraviolet light.   When the total amount of irradiation energy G1 of actinic rays irradiated to the coating film formed with the photopolymerizable composition and irradiation energy G2 of actinic rays irradiated to the coating film after heating is 100, G1 / G2 is The method for forming a coating film according to claim 1, which is 1/99 to 30/70.   A pre-curing step of partially curing the film formed of a photopolymerizable composition that is solid or viscous at room temperature by irradiating with actinic rays, a heating step of heating the partially cured coating, and A method of adjusting the gloss of the cured coating film by the irradiation energy of the actinic ray in the preliminary curing process, comprising a curing process in which the coating film after heating is irradiated and cured.

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