JP2022143794A - Manufacturing method of matte coating film - Google Patents

Abstract

To provide a manufacturing process for obtaining a coating film that has a desired designability using a fine particle-containing active energy ray-curable composition.SOLUTION: The solution of the present invention is based on a manufacturing process for matte coating film that is characterized by having a step (1) of irradiating a coating film made of an active energy ray-curable composition containing fine particles having a particle size of 50 μm or less provided on a substrate with ultraviolet ray in an atmosphere having an oxygen concentration of 21% or more, and a step (2) of irradiating electron beam or ultraviolet ray in an atmosphere having an oxygen concentration of less than 21%, in this order.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a method for producing a matte coating film using an active energy ray-curable composition.

In general, for the purpose of imparting an aesthetic appearance such as matting (sometimes referred to as low gloss), an electron beam curing type (sometimes referred to as an EB curing type) or an ultraviolet It is known to apply a coating agent to which a curable (sometimes referred to as UV curable) matting agent is added. (See Patent Document 1, for example)
In addition, when curing a coating agent to which a matting agent is added, an electron beam is irradiated while changing the oxygen concentration in multiple stages in an oxygen-containing inert gas atmosphere to cure the electron beam curable clear. Also known is a method for obtaining a highly weather-resistant matte decorative sheet that provides a sufficient matte effect and is remarkably excellent in weather resistance. (See Patent Document 2, for example)
However, even with these methods, there are cases where the desired matte effect cannot be obtained.

JP-A-2002-69332 JP-A-2001-87703

The problem to be solved by the present invention is to provide a production method for obtaining a coating film having a desired design by using an active energy ray-curable composition containing fine particles.

The present inventors conducted steps (1) and (2) of irradiating a coating film made of an active energy ray-curable composition containing fine particles of a specific size provided on a substrate with ultraviolet rays under a specific atmosphere. We have found that a method for producing a matte coating film having

That is, the present invention comprises a step (1) of irradiating a coating film made of an active energy ray-curable composition containing fine particles having a particle size of 50 μm or less provided on a substrate with ultraviolet rays in an atmosphere having an oxygen concentration of 21% or more. and a step (2) of irradiating electron beams or ultraviolet rays in an atmosphere with an oxygen concentration of less than 21%, in this order.

Further, in the present invention, the active energy ray-curable composition contains a polyfunctional (meth)acrylate as an active energy ray-curable compound and contains 0.5 to 50% by mass of fine particles having an average particle size of 50 μm or less, Provided is a method for producing a matte coating film containing 0.5% to 30% by mass of a photopolymerization initiator.

The present invention also provides a method for producing a matte coating film, wherein the integrated light quantity of ultraviolet irradiation in the step (1) is 20 mJ/cm ² to 1000 mJ/cm ² .

The present invention also provides a method for producing a matte coating film, wherein the integrated light quantity of ultraviolet irradiation in step (2) is 20 mJ/cm ² to 1000 mJ/cm ² or the dose of electron beam irradiation is 10 to 230 kGy.

The present invention also provides a method for producing a matte coating film, wherein the fine particles are silica having an average particle size of 25 μm or less.

The present invention also provides a method for producing a matte coating film, wherein the fine particles are resin beads having an average particle size of 50 μm or less.

Further, the present invention includes a step (1) of irradiating a coating film made of an active energy ray-curable composition containing fine particles provided on a substrate with ultraviolet rays in an atmosphere having an oxygen concentration of 21% or more, and electron beam irradiation or and a step (2) of irradiating ultraviolet rays in an atmosphere with an oxygen concentration of less than 21% in this order.

According to the manufacturing method of the present invention, a coating film with low gloss can be obtained more easily than before.

(Base material)
The substrate used in the present invention can be used without any particular limitation as long as it is a substrate for which a matte design is desired. For example, in the case of a decorative sheet for building materials, a general-purpose base sheet used for decorative sheets can be used as the base material.
The base sheet is not particularly limited, and a general decorative sheet (film) made of a general-purpose thermoplastic resin or paper is used.
Sheets (films) formed of thermoplastic resins include, for example, polyethylene, ethylene-α-olefin copolymer, polypropylene, polymethylpentene, polybutene, ethylene-propylene copolymer, propylene-butene copolymer, ethylene- Polyolefin resins such as vinyl acetate copolymer, ethylene-vinyl acetate copolymer saponified product, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic acid ester copolymer, polyvinyl chloride, polyethylene terephthalate (PET), polybutylene terephthalate, polyamide, polycarbonate, polyethylene naphthalate, ionomer, acrylic acid ester polymer, methacrylic acid ester polymer, and the like. The base sheet may be formed by using these resins alone or in combination of two or more.

The base sheet may be colored, and if necessary, fillers, matting agents, foaming agents, flame retardants, lubricants, antistatic agents, antioxidants, ultraviolet absorbers, light stabilizers, etc. may contain various additives. The thickness of the base sheet can be appropriately set according to the application of the final product, the method of use, etc., but is generally preferably 20 to 300 μm.

One side or both sides of the base sheet may be subjected to surface treatment such as corona discharge treatment, ozone treatment, plasma treatment, ionizing radiation treatment, dichromic acid treatment, etc., if necessary. For example, when corona discharge treatment is performed, the surface tension of the substrate sheet surface should be 30 dyne or more, preferably 40 dyne or more. The surface treatment may be carried out according to a conventional method for each treatment.

Examples of types of paper substrates for decorative sheets include thin paper, plain paper, reinforced paper, paper sheets such as resin-impregnated paper, titanium paper, and the like.

Also, a wooden decorative board or the like, which is widely used as a decorative board, may be used as the base material. Examples of the wooden base material for the wooden decorative board include known materials such as plywood, particle board, hardboard, MDF, etc., which have conventionally been used as wooden base materials for decorative boards, furniture, building members, and the like. Moreover, it does not matter what kind of manufacturing method these known base materials are obtained.
Furthermore, noncombustible materials that can be used as base materials include gypsum board, gypsum board, perforated board building materials made of calcium silicate board, etc.; , galvanized steel plate, polyvinyl chloride sol-coated steel plate, aluminum plate, copper plate and the like.

(Coating film made of active energy ray-curable composition)
A coating film comprising an active energy ray-curable composition is a coating film of a coating agent comprising an active energy ray-curable composition.
Hereinafter, the coating agent comprising the active energy ray-curable composition used in the present invention is referred to as "active energy ray-curable coating agent".

The active energy ray-curable coating agent used in the present invention contains a compound having a (meth)acryloyl group and a photopolymerization initiator.
In the present invention, "(meth)acryloyl group" refers to one or both of an acryloyl group and a methacryloyl group. Moreover, the "compound having a (meth)acryloyl group" may be referred to as (meth)acrylate. "(Meth)acrylate" refers to one or both of acrylate and methacrylate.

(Compound with (meth)acryloyl group)
The compound having a (meth)acryloyl group used in the present invention is not particularly limited and can be cured with a known active energy ray (hereinafter sometimes simply referred to as "active energy ray-curable"). can be used.
Examples of monofunctional (meth)acrylates include ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, hexadecyl (meth)acrylate, octadecyl (meth)acrylate, isoamyl (meth)acrylate, isodecyl (meth)acrylate, isostearyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, methoxyethyl (meth)acrylate, butoxy Ethyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, nonylphenoxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, glycidyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate , 2-hydroxy-3-phenoxypropyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate, diethylaminoethyl (meth)acrylate, nonylphenoxyethyltetrahydrofurfuryl (meth)acrylate, caprolactone-modified tetrahydrofurfuryl (meth)acrylates, isobornyl (meth)acrylates, dicyclopentanyl (meth)acrylates, dicyclopentenyloxyethyl (meth)acrylates, ethoxyethoxyethanol acrylic acid polymeric esters, and the like.

Examples of bifunctional (meth)acrylates include 1,4-butanediol di(meth)acrylate, 3-methyl-1,5-pentanediol di(meth)acrylate, and 1,6-hexanediol di(meth)acrylate. , neopentyl glycol di(meth)acrylate, 2-methyl-1,8-octanediol di(meth)acrylate, 2-butyl-2-ethyl-1,3-propanediol di(meth)acrylate, tricyclodecanedi Methanol di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, etc. dihydric alcohol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, tris(2-hydroxyethyl)isocyanurate di(meth)acrylate, 4 mol per 1 mol of neopentyl glycol di(meth)acrylates of diols obtained by adding ethylene oxide or propylene oxide, di(meth)acrylates of diols obtained by adding 2 mol of ethylene oxide or propylene oxide to 1 mol of bisphenol A, and the like. .

Trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol poly Poly(meth)acrylates of trihydric or higher polyhydric alcohols such as (meth)acrylates, tri(meth)acrylates of triols obtained by adding 3 mol or more of ethylene oxide or propylene oxide to 1 mol of glycerin, trimethylolpropane Di or tri(meth)acrylate of triol obtained by adding 3 mol or more of ethylene oxide or propylene oxide to 1 mol, diol of diol obtained by adding 4 mol or more of ethylene oxide or propylene oxide to 1 mol of bisphenol A Examples include poly(meth)acrylates of polyoxyalkylene polyols such as (meth)acrylates.

Furthermore, a mixture of dipentaerythritol hexaacrylate and dipentaerythritol pentaacrylate (sometimes abbreviated as DPHA), ditrimethylolpropane tetraacrylate (sometimes abbreviated as DTMPTA), which is a (meth)acrylate with two or more functions, Trimethylolpropane ethylene oxide adduct tri(meth)acrylate, which is a triol tri(meth)acrylate obtained by adding 3 mol or more of ethylene oxide to 1 mol of trimethylolpropane, may also be used. A typical example of the trimethylolpropane ethylene oxide adduct tri(meth)acrylate is trimethylolpropane ethylene oxide (hereinafter ethylene oxide may be referred to as "EO") modified (n≈3) triacrylate. be done.

Furthermore, a polymerizable oligomer may be used as necessary. Polymerizable oligomers include urethane (meth)acrylates, amine-modified polyether acrylates, amine-modified epoxy acrylates, amine-modified aliphatic acrylates, amine-modified polyester acrylates, amine-modified acrylates such as amino (meth)acrylates, and polyester (meth)acrylates. , polyether (meth)acrylate, polyolefin (meth)acrylate, polystyrene (meth)acrylate, epoxy (meth)acrylate, and the like.

Moreover, you may use resin which has a (meth)acryloyl group as a compound which has a (meth)acryloyl group used by this invention. Acrylic resins containing (meth)acryloyl groups are particularly preferred. (Meth)acryloyl group-containing acrylic resins are not particularly limited, and acrylic resins obtained by known methods can be used.

(Photoinitiator)
The active energy ray-curable coating agent of the present invention usually uses a photopolymerization initiator when it is cured with ultraviolet rays or the like. As the photopolymerization initiator used at this time, a known one may be used.

Among them, radical polymerization type photopolymerization initiators are preferable, and examples include α-hydroxyalkylketone photopolymerization initiators that do not cause discoloration of the solution when the active energy ray-curable compound is dissolved and cause little yellowing over time. Examples of α-hydroxyalkylketone photopolymerization initiators include 1-phenyl-2-hydroxy-2-methylpropan-1-one, 1-(4-i-propylphenyl)-2-hydroxy-2-methylpropane, -1-one, 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, 1-hydroxycyclohexylphenylketone and the like. Phenylglyoxolate-based photopolymerization initiators are also preferred. Examples of phenylglyoxolate-based photopolymerization initiators include methylbenzoyl formate and the like. Among them, 1-hydroxycyclohexylphenyl ketone is preferred.

Further, as other radical polymerization type photopolymerization initiators, monoacylphosphine oxide photopolymerization initiators having absorption wavelengths in the long wavelength region of ultraviolet rays may be used in appropriate combination. As the monoacylphosphine oxide-based photopolymerization initiator, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2,6 -dimethoxybenzoyl-diphenylphosphine oxide, 2,6-dichlorobenzoyl-diphenylphosphine oxide, 2,4,6-trimethylbenzoyl-phenylphosphine acid methyl ester, 2-methylbenzoyl-diphenylphosphine oxide, pivaloyl Examples include monoacylphosphine oxides such as phenylphosphinic acid isopropyl ester, and particularly, among these, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide has an emission wavelength of 385 nm or 395 nm. Having a UV absorption wavelength that matches the emission wavelength region of the LED is more preferable in terms of obtaining suitable curability and less yellowing of the cured film.

The photopolymerization initiators described above may be used alone, or two or more of them may be used in combination. The total amount of the photopolymerization initiator added is preferably in the range of 0.5% by mass to 30% by mass with respect to the total amount of the coating agent. More preferably, it is in the range of 1% by mass to 25% by mass with respect to the total amount of the coating agent.

(Organic solvent)
Moreover, the active-energy-ray-curable coating agent of this invention can also add the organic solvent as a diluent.
Any organic solvent can be used as long as it dissolves the compound having a (meth)acryloyl group. For example, aromatic hydrocarbons such as toluene and xylene; aliphatic or alicyclic hydrocarbons such as n-hexane, cyclohexane, methylcyclohexane, and ethylcyclohexane; esters such as ethyl acetate, butyl acetate, and propyl acetate; Alcohols such as ethanol, isopropyl alcohol and n-butanol, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, alkylene glycol monoalkyl ethers such as ethylene glycol monoethyl ether and propylene glycol monomethyl ether, propylene glycol monomethyl ether Ether esters such as acetate and the like are included.
However, for the purpose of environmental friendliness, it is more preferable not to contain the above-mentioned organic solvents in order to thoroughly reduce the amount of evaporation of organic solvents into the atmosphere, that is, to reduce volatile organic compounds (VOCs).

From the viewpoint of coatability, the active energy ray-curable coating agent of the present invention is preferably adjusted to a viscosity that allows coating in the method for producing a decorative sheet for building materials of the present invention, which will be described later. It is preferable to adjust the viscosity to 40 to 3000 mPa·s. Most of the (meth)acryloyl group-containing compounds generally have low molecular weights, and if the viscosity can be adjusted without dilution with an organic solvent, it is not necessary to dilute with an organic solvent. On the other hand, when a polymerizable oligomer having a high molecular weight and a high viscosity is used together, the viscosity can be adjusted by diluting with an organic solvent or heating.

(Fine particles with an average particle diameter of 50 μm or less)
The fine particles having an average particle size of 50 μm or less used in the present invention may be organic and/or inorganic, and may be used alone or in combination as long as they are known. Specifically, for example, silica, titanium oxide, alumina particles (aluminum oxide), calcium carbonate, barium sulfate, inorganic particles such as glass, or organic particles such as acrylic resin, urethane resin, polycarbonate resin, silicone resin, polystyrene resin, silicone Beads or the like can be used. Inorganic fine particles such as silica and aluminosilicate beads, and organic fine particles such as acrylic resin beads, urethane resin beads, silicone beads, etc., are preferable as those from which a high matting effect can be expected. By further adding beads to silica as the matting agent, there is an advantage that the scratch resistance of the coated surface can be improved in addition to design properties such as moderately low luster and touch.

(silica)
Silica used in the present invention is not particularly limited as long as it has an average particle size of 25 μm or less, and known silica can be used. Let the average particle diameter be the value measured by the laser diffraction method in this invention.
More specifically, amorphous silica is more preferred as silica. Examples of the amorphous silica include diatomaceous earth, activated clay, and the like. Among amorphous silica, dry silica, wet silica, silica gel, and the like can be used as synthetic amorphous silica. Among them, wet silica produced by neutralization or decomposition reaction of an aqueous solution of sodium silicate with an acid or an alkali metal salt is preferred. The wet silica may be surface-treated. The method for surface-treating the silica particles is not particularly limited, and any known method may be used. Examples include those surface-treated with wax or silane coupling agents. Wet silica may be used by mixing a plurality of the above-mentioned surface-treated and non-surface-treated silicas.

The average particle size of the wet silica used as the matting agent is 25 μm or less, more preferably 15 μm or less. If the average particle size is more than 25 μm, the particles are likely to fall off, resulting in a change in luster and scratches.

The content of silica is preferably 0.5 to 50% by mass, more preferably 1 to 30% by mass, in terms of solid content of the total amount of the coating agent. If the content is less than 0.5% by mass, a sufficient matting effect cannot be obtained, and if it exceeds 50% by mass, it tends to come off from the surface of the silica coating film, which is undesirable.

The average particle size of the beads used as the matting agent is 50 μm or less, more preferably 15 μm or less. If the average particle size is more than 50 μm, the beads are likely to fall off or be buried, resulting in a change in luster and scratches.

The bead content is preferably 0.5 to 50% by mass, more preferably 0.5 to 30% by mass, in terms of solid content of the total amount of the coating agent. If the mass exceeds 50%, the beads tend to fall off from the coating film surface, which is not preferable.

(Additive)
In addition, the active energy ray-curable coating agent of the present invention includes a polymerization inhibitor, a leveling agent, a thixotropic agent, a wax, a drying agent, a thickener, an anti-sagging agent, a plasticizer, a dispersant, an anti-settling agent, and an anti-foaming agent. agents, UV absorbers, light stabilizers, and the like.

(Production of active energy ray-curable coating agent)
The active energy ray-curable coating agent used in the present invention can be produced by mixing and kneading and dispersing a compound having a (meth)acryloyl group, a photopolymerization initiator, fine particles, and various other additives.
The particle size distribution of the filler of the active energy ray-curable coating agent used in the present invention can be adjusted by appropriately adjusting the size of the grinding media of the disperser, the filling rate of the grinding media, the dispersion treatment time, and the like. As the dispersing machine, commonly used roller mills, ball mills, pebble mills, attritors, sand mills and the like can be used.
If air bubbles or unexpectedly large particles are contained in the coating agent, it is preferable to remove them by filtration or the like, as they lower the quality of the coated product. A conventionally known filter can be used.

(Method for forming coating film)
The active energy ray-curable coating agent used in the present invention can form a coating film by a known coating/printing method. Specific examples of coating methods include roll coater, gravure coater, gravure offset coater, flexo coater, air doctor coater, blade coater, air knife coater, squeeze coater, impregnation coater, transfer roll coater, kiss coater, and curtain coater. , a cast coater, a spray coater, a die coater, an offset printer, a screen printer, and the like can be used as appropriate.

When the coating agent to be used contains an organic solvent, the coating film formed by the above formation method is obtained by drying the solvent in a drying oven or the like and then curing with active energy rays to obtain a cured coating film.

(Step (1))
Step 1 in the production method of the present invention is a step of irradiating the coating film composed of the active energy ray-curable composition provided on the substrate with ultraviolet rays in an atmosphere having an oxygen concentration of 21% or more.
An atmosphere having an oxygen concentration of 21% or higher is an atmosphere filled with an oxygen-containing inert gas having an oxygen concentration of 21% or higher. As the inert gas, one or a mixture of a plurality of gases such as nitrogen gas, carbon dioxide gas, and argon gas may be used. In addition, there is no problem even if a small amount of gas such as carbon dioxide contained in the air is contained. Specifically, the coating film is irradiated with ultraviolet rays in an environment filled with these gases and an oxygen gas adjusted to have an oxygen concentration of 21% or more.

The oxygen concentration in step 1 is preferably 40% or higher, more preferably 50% or higher. On the other hand, the upper limit of the oxygen concentration in step 1 is not particularly limited, but it is preferably 90% or less, more preferably 80% or less, because surface physical properties such as scratch resistance may deteriorate. . More preferably, it is 70% or less.

Here, ultraviolet irradiation can be performed by a known method. For example, germicidal lamp, ultraviolet fluorescent lamp, ultraviolet light emitting diode (UV-LED), carbon arc, metal halide lamp, xenon lamp, chemical lamp, low pressure mercury lamp, high pressure mercury lamp for copying, medium or high pressure mercury lamp, ultra high pressure mercury lamp, Ultraviolet rays are irradiated using an electrodeless lamp, a metal halide lamp, natural light, or the like as a light source. Curing efficiency is good if the amount of ultraviolet light during curing is 20 mJ/cm ² or more.

The cumulative amount of UV light in step (1) is preferably in the range of 20 mJ/cm ² to 1000 mJ/cm ² in order to maximize the effects of the present invention. Among others, it is more preferable that the integrated amount of light is in the range of 40 mJ/cm ² to 800 mJ/cm ² .

The thickness of the coating film thus obtained is preferably in the range of 0.1 to 100 μm, most preferably in the range of 0.5 to 50 μm. By setting the film thickness within this range, the effects of the present invention can be maximized.

(Step (2))
After the step (1), the coating film is further irradiated with electron beams or ultraviolet rays in an atmosphere with an oxygen concentration of less than 21% (step (2)).
An atmosphere with an oxygen concentration of less than 21% may be used for both electron beam irradiation and ultraviolet irradiation, but an oxygen concentration of 15% or less is more preferable for ultraviolet irradiation.
Here, the atmosphere having an oxygen concentration of less than 15% means an atmosphere filled with an inert gas containing oxygen and having an oxygen concentration of less than 15%. As the inert gas, one or a mixture of a plurality of gases such as nitrogen gas, carbon dioxide gas, and argon gas may be used. In addition, there is no problem even if a small amount of gas such as carbon dioxide contained in the air is contained.

Incidentally, the ultraviolet irradiation conditions and the integrated amount of light may be the same as in the step (1).

On the other hand, when an electron beam is used, an electron beam irradiation device is used. The irradiation dose is preferably about 10 to 230 kGy, more preferably about 10 to 100 kGy.

The reason why the desired matte coating film can be efficiently obtained by the manufacturing method of the present invention is not clear, but is presumed as follows.
That is, in the step (1), ultraviolet rays are irradiated in a state of high oxygen concentration. At that time, the curing reaction of the coating film surface of the active energy ray-curable coating agent is inhibited, while the reaction progresses from the inside of the coating film. It is presumed that cure shrinkage progresses. At that time, it is presumed that the fine particles of the matting agent or the like are pushed up, and the fine particles efficiently move to the film surface.

Moreover, the manufacturing method of the present invention can be widely used not only for building materials such as decorative sheets, but also for surface coating of furniture, musical instruments, office supplies, sporting goods, toys, and the like.

The present invention will be described in more detail below with reference to examples. Parts and parts by mass in the following examples represent % by mass.
The average particle diameter of the fine particles was measured using a nanoparticle particle size distribution analyzer Nanotrac UPA EX-150 manufactured by Nikkiso Co., Ltd.

(Adjustment Example 1 Active energy ray-curable composition)
60 parts by mass of trifunctional acrylate monomer "Miramer M3130" manufactured by MIWON, 5 parts by mass of 1-hydroxy-cyclohexyl-phenyl-ketone "Omnirad184" manufactured by BASF, and 5 parts by mass of silica "Nip Seal E170" manufactured by Tosoh Silica Co., Ltd. Mixed. , and stirred with a stirrer for about 1 hour to prepare an active energy ray-curable composition of Preparation Example 1 used in Example 1, which is 70 parts by mass in total.

The active energy ray-curable compositions of each adjustment example and each comparative adjustment example were obtained in the same manner as in adjustment example 1, except that the raw materials used and the amounts used were different. The details of the composition, such as raw materials and amounts used, are as shown in the table. In addition, the following raw materials were used in the table.
・Miramer M3130: Trifunctional acrylate monomer manufactured by MIWON ・Miramer M202: Bifunctional acrylate monomer manufactured by MIWON ・Nip seal E170: Silica manufactured by Tosoh Silica Co., Ltd. ・Silysia 450: Silica manufactured by Fuji Silysia Chemical ・Omnirad184: BASF Photopolymerization initiator GR-800: Acrylic beads manufactured by Negami Kogyo Co., Ltd. C-800: Urethane beads manufactured by Negami Kogyo Co., Ltd. X-52-1621: Silicone powder manufactured by Shin-Etsu Chemical Co., Ltd.

(Method for producing coating film)
(Coating method)
The active energy curable composition obtained in the adjustment example was applied to an easy-adhesion treated polyethylene terephthalate film (hereinafter referred to as PET film, A4300 manufactured by Toyobo Co., Ltd., thickness 100 μm) by a bar coater coating method to form a film of 30 μm. formed a layer.

(Step 1)
In the step (1) of irradiating the coating layer with ultraviolet rays in an atmosphere having an oxygen concentration of 21% or more, an ultraviolet irradiation device manufactured by GS Yuasa Corporation was used as the ultraviolet irradiation device. As an integrated light intensity measuring device (illuminometer), an ultraviolet integrated light intensity meter "Industrial UV Checker UVR-N1" manufactured by GS Yuasa Corporation was used.
The oxygen concentration and the integrated amount of light during irradiation are shown in the table for each example.

(Step 2)
In step (2) of irradiating the coating layer after step 1 with electron beams or ultraviolet rays in an atmosphere with an oxygen concentration of less than 21%, the ultraviolet irradiation device used was a UV irradiation device manufactured by GS Yuasa Corporation. . As an electron beam irradiation device, "Electrocurtain EC250/15/180L" manufactured by Iwasaki Electric Co., Ltd. was used. In step 2, the ultraviolet irradiation was standardized at 56 mJ/cm ² and the electron beam irradiation was standardized at 30 kGy. The oxygen concentration at the time of irradiation is shown in the table for each example.
A coating film was obtained as described above.

(Evaluation item 1: Gloss)
The glossiness of the resulting coating film was measured using the following equipment and conditions. It can be said that the higher the gloss reduction rate, the higher the matting effect.
Apparatus used: "MULTI GLOSS 268A" manufactured by Konica Minolta
Measurement conditions: Incident angle 60° Reflection angle 60°
Gloss reduction rate=(gloss value under reference condition (comparative example)−gloss value in example)/gloss value under reference condition (comparative example) The evaluation criteria for the gloss reduction rate are as follows.
◎: 40% or more ○: 20% or more and less than 40% △: 10% or more and less than 20% ×: less than 10%

(Evaluation item 2: scratch resistance)
Steel wool (“BON STAR No. 0000” manufactured by Nippon Steel Wool Co., Ltd.) was reciprocated on the surface of the obtained coating film with a load of 1.5 kg. The degree of damage to the coating film was evaluated according to three grades of criteria.
Evaluation criteria for scratch resistance are as follows.
A: No change, or slight change in luster, but no streak-like flaws.
B: A streak-like flaw enters the area of half or less of the friction surface.
C: Almost the entire surface of the rubbing surface had streak-like scratches, and the coating film turned white and was unusable.

(Evaluation item 3: tactile sensation)
About the obtained coating film, the sensory evaluation of the feel of the coating film was requested to three people at random. Comparative Example 1 containing no beads, and Comparative Example 13 and Example 20, which had the same composition as the object but had different curing conditions, were compared.
The evaluation criteria for tactile sensation are as follows.
○: Significant change in tactile sensation △: Slight change in tactile sensation ×: No change at all

The results are shown in the table. In addition, the table|surface hollow column represents non-compounding.

Table 1 is an example of using a trifunctional monomer and changing the oxygen concentration in step 1.
As a result, the coating films of Examples 1 to 5 had a lower gloss value than Comparative Example 1, and the effect was particularly remarkable at an oxygen concentration of 60%. On the other hand, when the oxygen concentration exceeded 80%, deterioration in scratch resistance was observed.

Table 2 is an example of using a bifunctional monomer and changing the oxygen concentration in step 1. As a result, the coating film of Example 7 had a lower gloss value than that of Comparative Example 2.

Table 3 is an example in which the oxygen concentration in step 2 is changed. Compared to Comparative Example 3, the coating films of Examples 8 to 10 gave lower gloss values.

Table 4 is an example of varying the silica particle size in the coating composition. Compared to Comparative Examples 4 and 5, the coating films of Examples 11 and 12 gave lower gloss values.

Table 5 shows examples in which the amount of silica agent in the coating composition was changed. Compared to Comparative Examples 6, 7 and 8, the coating films of Examples 13, 14 and 15 gave lower gloss values.

Table 6 shows examples in which the amount of photopolymerization initiator in the coating composition was changed. Compared to Comparative Examples 9, 10 and 11, the coating films of Examples 16, 17 and 18 gave lower gloss values.

Table 7 is an example of blending organic fine particles in the coating composition. Compared to Comparative Examples 12, 13 and 14, the coating films of Examples 19, 20 and 21 gave lower gloss values.
Furthermore, when urethane beads were used, a change in tactile sensation was also felt.

Table 8 shows an example in which the integrated amount of light in process 1 is changed. The cumulative amount of light was 150 or more, and a very high decrease in gloss was obtained.

According to the manufacturing method of the present invention, a coating film having a low glossiness can be obtained more easily than before.

Claims (7)

A step (1) of irradiating a coating film made of an active energy ray-curable composition containing fine particles having a particle size of 50 μm or less and provided on a substrate with ultraviolet rays in an atmosphere having an oxygen concentration of 21% or more; A method for producing a matte coating film, characterized by comprising a step (2) of irradiating electron beams or ultraviolet rays in an atmosphere of less than 21% in this order. The active energy ray-curable composition is
Contains a polyfunctional (meth)acrylate as an active energy ray-curable compound,
Containing 0.5 to 50% by mass of fine particles having an average particle size of 50 μm or less,
2. The method for producing a matte coating film according to claim 1, wherein the photopolymerization initiator is contained in an amount of 0.5% by mass to 30% by mass. 3. The method for producing a matte coating film according to claim 1 or 2, wherein the integrated light quantity of ultraviolet irradiation in the step (1) is 20 mJ/cm ² to 1000 mJ/cm ² . 4. The production of a matte coating film according to any one of claims 1 to 3, wherein the integrated light quantity of ultraviolet irradiation in step (2) is 20 mJ/cm ² to 1000 mJ/cm ² or the dose of electron beam irradiation is 10 to 230 kGy. Method. 2. The method for producing a matte coating film according to claim 1, wherein the fine particles are silica having an average particle size of 25 μm or less. 2. The method for producing a matte coating film according to claim 1, wherein the fine particles are resin beads having an average particle size of 50 μm or less. A step (1) of irradiating a coating film made of an active energy ray-curable composition containing fine particles provided on a substrate with ultraviolet rays in an atmosphere having an oxygen concentration of 21% or more;
A method for making a surface layer of a coating film matt, characterized by comprising a step (2) of irradiating an electron beam or irradiating an ultraviolet ray in an atmosphere with an oxygen concentration of less than 21% in this order.