JPH09277700A - Liquid-like composition for laser marking, article and method for marking - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide excellent spray coating, gravure printability without solvent, and excellent properties of adhesive properties, heat resistance, water resistance, moisture resistant heat and color development by incorporating energy beam curable resin and laser beam absorbing compound as indispensable components, and specifying the viscosity. SOLUTION: The composition for laser marking comprises energy beam curable resin, and compound for absorbing laser beam as indispensable components so that the viscosity at 60 deg.C by E type visometer is 20cPs or less. The energy beam curable resin is curable by ultraviolet ray or electron beam, and radical polymerization type is preferable. The compound for absorbing the laser has laser beam absorbing capacity to exhibit white color by emitting the laser, polyvalent metal hydroxide, organic aluminum compound, or salts of boric acid, silicic acid, phosphoric acid, oxalic acid. The molding to be marked with the composition for marking is coated by a spray coating method, irradiated with an energy beam to be cured, and irradiated with laser beam to obtain a white mark.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser marking composition and a laser marking method suitable for spray-coating the surface of a molded article and providing a clear white mark by irradiation with a laser beam.

[0002]

2. Description of the Related Art In recent years, electronic parts such as ICs, resistors, capacitors and inductors, electric parts such as relays, switches, connectors and printed circuit boards, housings for electric products, automobile parts, machine parts, cables, sheets and packaging. Use marking ink to mark characters and symbols such as manufacturer name, article name, date of manufacture, lot number, etc. on the surface of various containers such as sheets, cards, foods or medicines, caps of containers, labels, etc. The conventional printing method or ink jet marking method has become widespread. However, these methods require a long time from the process of printing to the drying of ink, the difficulty of marking fine parts, the maintenance of print quality, the complexity of management, the high cost, and the use of solvents. There is a problem such as environmental pollution, and rationalization is desired.

Recently, in order to rationalize marking, a laser marking method has been used in which the surface of a component or the like is directly irradiated with laser light and a part of the surface is etched by thermal decomposition or evaporation to perform marking. However, in this marking method, since there are various materials for the parts to be marked, there is a problem in that clear marking cannot be performed depending on the material, or in the case of a colored material, it is difficult to obtain a clear mark. .

As a method for solving the above problems, laser-markable energy ray-curable resin is applied to the surface of a marking object such as electronic parts, electric parts, housings, packages, etc., and the resin is then cured by laser light. A method of marking by etching is known. This method has the advantage that it can be performed in a short time, marking fine products, and good marking can be obtained. However, in the case of laser marking ink using energy ray curable resin,
It is usually applied by a method such as pad printing, offset printing, or screen printing, and the viscosity required for it is in the high viscosity range of several thousand to tens of thousands cps with an E-type viscometer in order to impart printability and adhesion to the substrate. It is in. However, when printing or applying to products produced at a very high speed, a coating method such as spray coating or gravure printing is adopted, and the viscosity required for this is generally a viscosity of 50 cps or less at room temperature with an E-type viscometer. Is required. It may be possible to dilute the high viscosity ink used in pad printing, offset printing or screen printing with a solvent to reduce the viscosity, but in this case an extra step of volatilizing the solvent is required It is an impractical means because there is a problem of air pollution due to the diffusion of the ash into the atmosphere.

[0005]

[Problems to be Solved by the Invention] White suitable for spray coating without solvent and excellent in gravure printing, and excellent in adhesiveness to a substrate, heat resistance, water resistance, moist heat resistance, and color development. There is a need for colored laser marking compositions.

[0006]

The inventors of the present invention have reached the present invention as a result of intensive studies to solve the above-mentioned problems. That is, the present invention contains (1) an energy ray-curable resin and a compound that absorbs laser light as essential components, and has a viscosity of 20 c in an E-type viscometer at 60 ° C.
a liquid composition for marking having a ps or less, (2) the energy ray-curable resin has a viscosity of 2 at 60 ° C. in an E-type viscometer
(1) Liquid composition for laser marking, which is a resin of 0 cps or less, (3) Energy ray curable resin is composed of an acrylate resin having a cyclic structure in the molecule and another energy ray curable resin, The liquid composition of (2) in which the viscosity of one or both of the resins is 50 cps or less as measured by an E-type viscometer at 25 ° C., and (4) the acrylate resin having a cyclic structure in the molecule is dicyclopentanil. Ring, dicyclopentenyl ring, isobornene ring, morpholine ring, benzene ring, cyclohexane ring, cyclohexene ring, piperidine ring, naphthalene ring, piperazine ring, pyrimidine ring, furan ring, imidazole ring, imidazoline ring, imidazolidine ring, pyridine ring, Acryl having picoline ring, quinarizone ring, anthracene ring or fluorene ring The liquid composition of a preparative resin (3),

(5) The acrylate resin having a cyclic structure in the molecule and having a viscosity of 50 cps or less measured by an E-type viscometer at 25 ° C. is a monoacrylate resin having a cyclic structure in the molecule. Liquid composition, (6) Monoacrylate resin having a cyclic structure in the molecule has one or more of dicyclopentanyl ring, dicyclopentenyl ring, isobornene ring, morpholine ring, benzene ring and cyclohexene ring. It is a monoacrylate resin (5)
(7) a monoacrylate resin having a cyclic structure in the molecule is dicyclopentanyl acrylate, dicyclopentanyl methacrylate, dicyclopentenyloxyethyl acrylate, dicyclopentenyloxyethyl methacrylate, isobornyl acrylate, Isobornyl methacrylate, morpholine acrylate,
A liquid composition of (5) which is phenoxydiethylene glycol acrylate or cyclohexyl acrylate;

(8) Compounds which absorb laser light are hydroxides of polyvalent metals, organoaluminum compounds, borates,
The laser marking composition of (1) to (7), which is a silicate, a phosphate or an oxalate, and (9) the compound that absorbs laser light has an absorption peak in the infrared absorption spectrum in the range of 900 to 1000 cm ^-1. A laser marking composition which is an inorganic compound (1) to (6),
(10) The composition for laser marking according to (9), wherein the inorganic compound having an infrared absorption spectrum absorption peak in the range of 900 to 1000 cm ⁻¹ is aluminum hydroxide.
1) The ratio of the energy ray-curable resin to the total solid content of the laser marking composition is 30 to 98% by weight, and the ratio of the compound that absorbs laser light is 2 to 70% by weight (1) to (10). ) Laser marking composition, (12) Laser marking article having a cured coating of the laser marking composition of (1) to (11) on the surface of the article, (13) Article is bottle, cap, card, label (12) Laser marking article, which is a class or can, (14) Laser marking article (12) or (13), wherein the cured film has a thickness of 3 to 50 μm.

(15) In producing the article of (12) to (14), the surface of the article is coated with the composition for laser marking of (1) to (11) by a spray coating method and then irradiated with energy rays. (16) A method for producing a laser marking article, which is characterized in that the energy rays are ultraviolet rays or electron rays (1
5) A method for producing an article for laser marking, (17)
(12) to (14) a laser marking method characterized by irradiating a cured film layer formed on the surface of the article with a laser beam, (18) a laser marking method according to (17), wherein the laser beam is an infrared laser, (1
9) The infrared laser light is a far infrared laser (1
7) or (18) laser marking method, (20)
The laser marking method according to any one of (17) to (19), wherein the energy of the laser beam is 1.0 to 6.0 J / cm ² .

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The liquid composition for laser marking of the present invention contains an energy ray-curable resin and a compound that absorbs laser light as essential components, and has a viscosity at 60 ° C. of not more than 20 cps in an E-type viscometer. belongs to. The energy ray-curable resin used in the present invention is a resin curable by energy rays such as infrared rays, visible light rays, ultraviolet rays, and electron rays, preferably ultraviolet rays, and a resin curable by electron rays, a radical polymerization type, Alternatively, a cationic polymerization type resin can be used, but a radical polymerization type resin is preferable. The resin is a mixed resin of an acrylate resin having a cyclic structure in the molecule (preferably a monoacrylate resin) and another energy ray-curable resin, and the viscosity of either or both resins is 25 ° C. It is preferable that the value measured by the E-type viscometer is 50 cps or less from the viewpoint of the adhesion to the substrate, especially the adhesion to aluminum.

Examples of the radical-polymerizable resin used in the present invention include acrylates having a cyclic structure in the molecule, monoacrylates, diacrylates, triacrylates of various alcohols, acrylates of modified alcohols, vinyl ethers and the like. To be

Examples of the acrylate having a cyclic structure in the molecule include dicyclopentane ring, dicyclopentenyl ring, isobornene ring, morpholine ring, benzene ring, cyclohexane ring, cyclohexene ring, piperidine ring, naphthalene ring, piperazine ring and pyrimidine ring. Ring, furan ring,
Imidazole ring, imidazoline ring, imidazolidine ring,
Examples thereof include acrylates having a pyridine ring, a picoline ring, a quinazoline ring, a quinazolidine ring, an anthracene ring, and a fluorene ring. Acrylates having a cyclic structure in these molecules are preferably dicyclopentane ring,
An acrylate having a dicyclopentenyl ring, an isobornene ring, a morpholine ring, a benzene ring, and a cyclohexane ring, and more preferably an acrylate having a viscosity of 50 cps or less measured by an E-type viscometer at 25 ° C. Monoacrylates having a cyclopentane ring, a dicyclopentenyl ring, an isobornene ring, a morpholine ring, a benzene ring or a cyclohexane ring, specifically, dicyclopentanyl acrylate, dicyclopentanyl methacrylate, dicyclopentanyl dimethacrylate. , Dicyclopentenyloxyethyl acrylate, dicyclopentenyloxyethyl methacrylate, isobornyl acrylate, isobornyl methacrylate, morpholine acrylate, morpholine methacrylate, phenoxy Ethylene glycol methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, and the like. Further, from the viewpoint of adhesion to the base material, monoacrylates having a dicyclopentane ring, a dicyclopentanyl ring, an isobornene ring, a morpholine ring, a benzene ring or a cyclohexane ring as a cyclic structure in the molecule, Includes dicyclopentanyl acrylate, dicyclopentanyl methacrylate, dicyclopentanyloxyethyl acrylate, dicyclopentanyloxyethyl methacrylate, isobornyl acrylate, isobornyl methacrylate, morpholine acrylate, morpholine methacrylate, Phenoxydiethylene glycol methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate and the like can be mentioned.

Examples of monoacrylates of various alcohols include 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, lauryl acrylate, stearyl acrylate, paramyl acrylate,
Examples thereof include acrylates of C1-C23 saturated or unsaturated alcohols such as oleyl acrylate, and preferably the viscosity by an E-type viscometer at 25 ° C. is 50 cps.
The following C8 to C23 saturated or unsaturated alcohol acrylates, and more preferably C12 or higher saturated or unsaturated alcohol acrylates, such as lauryl acrylate, stearyl acrylate, palmityl acrylate, and oleyl acrylate. .

Examples of diacrylates and triacrylates of various alcohols include ethylene glycol, propylene glycol, butanediol, pentanediol, heptanediol, octanediol, diethylene glycol, triethylene glycol, dipropylene glycol, polypropylene glycol and glycerin. Examples thereof include polyhydric alcohol di- or triacrylates, preferably ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, and other polyhydric alcohol di- or triacrylates. And more preferably,
Diacrylates or triacrylates having a viscosity by E-type viscometer at 25 ° C. of 50 cps or less, for example, di- or triacrylates of polyhydric alcohols such as ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, neopentyl glycol. Specific examples thereof include diethylene glycol diacrylate, diethylene glycol dimethacrylate, tripropylene glycol diacrylate and neopentyl glycol diacrylate, with diethylene glycol diacrylate, tripropylene glycol diacrylate and neopentyl glycol diacrylate being preferred.

In the case of monohydric alcohol, the acrylates of denatured alcohol are acrylated denatured denatured alcohols using a modifier that produces a hydroxyl group by denaturation, and in the case of polyhydric alcohol, the hydroxyl group of polyhydric alcohol. Is an acrylated alcohol modified with a modifier which may have a hydroxyl group capable of reacting with a hydroxyl group. As a modifier, butyrolactone, caprolactone, epichlorohydrin, ethylene oxide, propylene oxide, butylene oxide, C1
To C6 aliphatic aldehydes, benzaldehyde, p-methoxybenzaldehyde, p-hydroxybenzaldehyde, p-nitrobenzaldehyde, p-chlorobenzaldehyde, and other aromatic aldehydes, C1-C6 aliphatic carboxylic acids, benzoic acid, phthalic acid, Aromatic carboxylic acids such as p-hydroxybenzoic acid, p-nitrobenzoic acid, p-hydroxybenzoic acid and p-chlorobenzoic acid, and fatty acids having a hydroxyl group such as lactaldehyde, tartaraldehyde, citroaldehyde and hydropivalaldehyde Aliphatic carboxylic acids having a hydroxyl group such as group aldehydes, lactic acid, tartaric acid, citric acid, hydropivalic acid, etc., preferably caprolactone, epichlorohydrin,
Hydropivalyl aldehyde, hydropivalic acid, a modified acrylate resin modified with ethylene oxide, more preferably caprolactone, epichlorohydrin, hydropivalyl aldehyde, hydropivalic acid having a viscosity of 50 cps or less measured by an E-type viscometer at 25 ° C., It is a modified acrylate resin modified with ethylene oxide, and includes, for example, caprolactone-modified 2-hydroxy acrylate, hydroxypiparic acid-modified neopentyl glycol diacrylate, and 2- (2- (ethyloxy).
Ethyloxy) ethyl acrylate is exemplified, and caprolactone-modified 2-hydroxyacrylate, hydroxypivalic acid-modified neopentylglycol diacrylate, and 2- (2 (ethyloxyethyl) ethyloxy) ethyl alcohol are preferable.

When a resin having a viscosity of 50 cps or less measured by an E-type viscometer at 25 ° C. is used as the energy ray-curable resin, various acrylates having a viscosity of 50 cps or higher measured by the E-type viscometer at 25 ° C. Adhesiveness and curability can be further improved by adding compounds, various oligomers, vinyl ethers, or epoxy resins to the extent that they do not affect the viscosity of the liquid composition. 25
As various acrylates having a viscosity of 50 cps or more measured by an E-type viscometer at ℃, an acrylate having one or more of dicyclopentanyl ring, dicyclopentenyl ring, isobornene ring, morpholine ring, benzene ring, and cyclohexane ring. -Based resin, caprolactone-modified acrylate-based resin, epichlorohydrin-modified acrylate-based resin, hydropivalylaldehyde-modified acrylate-based resin, hydropivalic acid-modified acrylate-based resin, ethylene oxide-modified acrylate-based resin, monoacrylate-based resin, di- or triglycol acrylate-based resin 1 or 2 or more kinds of acrylate resins, and preferred are epichlorohydrin-modified 1,6-hexanediol diacrylate and ethylene oxide. Sex trimethyl propanone triacrylate, pentaerythritol triacrylate, polyethylene glycol diacrylate, trimethylolpropane triacrylate, 5-ethyl-2-
(2-Hydroxy-1,1-dimethylethyl) -5-
(Hydroxymethyl) -1,3-dioxane diacrylic acid ester and the like can be mentioned.

As the oligomers, epoxy acrylate oligomers such as epoxidized soybean oil acrylate, acrylates based on various bisphenol A type epoxy resins, epoxidized linseed oil acrylate and modified bisphenol A diacrylate, the following formula (1)

[0018]

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Polyester acrylate oligomers such as reaction products of polyester and acrylic acid based on a dibasic acid and an aliphatic diol as shown in the following formula (2)

[0020]

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Aliphatic or aromatic urethane acrylates obtained by reaction with aliphatic or aromatic isocyanates based on the polyols or polyesters shown in (1) and the like can be mentioned. The amount of these oligomers added is such that the composition has a viscosity of 20 c at 60 ° C. in an E-type viscometer.
It may be blended so as to be less than ps, but usually 20% by weight
Or less, preferably 15% by weight or less, more preferably 10% by weight or less.
% By weight or less.

Examples of vinyl ethers include ethyl vinyl ether, n-butyl vinyl ether, n-dodecyl vinyl ether, n-octadecyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexanedimethanol monovinyl ether, cyclohexyl vinyl ether, 1,4-cyclohexanedimethanol divinyl ether. , Hydroxybutyl vinyl ether,
1,6-hexanediol divinyl ether, diethylene glycol divinyl ether, dipropylene glycol divinyl ether, tripropylene glycol divinyl ether, triethylene glycol divinyl ether, propylene carbonate propenyl ether are mentioned, and preferably ethyl vinyl ether, n-butyl vinyl ether, n. -Dodecyl vinyl ether, n-octadecyl vinyl ether, 2-ethylhexyl vinyl ether, hydroxybutyl vinyl ether, 1,6-
Hexanediol divinyl ether, diethylene glycol divinyl ether, dipropylene glycol divinyl ether, tripropylene glycol divinyl ether, and triethylene glycol divinyl ether.

These acrylates and vinyl ethers may be used alone or in combination of two or more within a range that does not affect the viscosity. In order to satisfy the required physical properties such as adhesion, they are generally used as a mixture. . Further, the above radical polymerization type resin can also be used as a cation polymerization type resin.

Examples of the cation-polymerizable resin include the above-mentioned acrylates and vinyl ethers, and epoxy resins are also used. Epoxy resins include bisphenol A, bisphenol F, bisphenol S, bisphenol C, 4,4'-thiodiphenol, 4,4'-biphenylphenol, 2,2'-methylene-bis (4-methyl-6-tert-). Butylphenol), 2,2'-methylene-bis (4-ethyl-6-
tert-butylphenol), 4,4'-butylylene-bis (3-methyl-6-tert-butylphenol), 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenol), trishydroxy. It is a glycidyl etherified product of a polyphenol compound such as phenylmethane, pyrogallol, resorcinol, benzenetriols, phenols having a diisopropylidene skeleton, and phenols having a fluorene skeleton such as 1,1-di-4'-hydroxyphenylfluorene. Polyfunctional epoxy resin, phenol, phenol, cresol, naphthol, phenylene skeleton, toluylene skeleton, xylylene skeleton, aromatic skeleton such as naphthalene skeleton, and alicyclic skeleton such as dicyclopentadiene No Epoxy resins are glycidyl ethers of rack resins. These epoxy resins may be used as a mixture with acrylates and / or vinyl ethers.

In the liquid composition of the present invention, it is preferable to use a photoinitiator for curing. As such an initiator, a thioxanthone type, anthraquinone type, acetophenone type, benzoin ether type, benzophenone type radical polymerization type resin is used. Type, amine type photoinitiators, and cationic polymerization resins include aromatic diazonium salts, aromatic halonium salts, metallocene compounds and other photoinitiators.
These photoinitiators may be used alone or in combination of two or more. When a cationic polymerization type resin is used for curing, the curing temperature is in the range of 80 to 170 ° C., particularly preferably 100 to 170 ° C. in order to further complete the curing.
It is desirable to heat in the range of 150 ° C. The heating time varies depending on the temperature, but is usually 5 to 30 minutes.

The compound which absorbs laser light used in the present invention is not particularly limited as long as it has a laser light absorption ability and exhibits a white color upon irradiation with laser light, but the color of the compound itself is, for example, It is preferable to have a white color such as a pastel color such as white or reddish white, bluish white, yellowish white, blackish white, etc., for example, a hydroxide of a polyvalent metal, an organic aluminum compound, a borate salt. , Silicates, phosphates, oxalates and the like. The proportion of the compound that absorbs laser light in the laser marking composition of the present invention is preferably in the range of 2 to 70% by weight, more preferably 5 to 60% by weight, still more preferably 10 to 50% by weight. It should be noted that the white color includes those having transparency such as colorless and transparent and colored and transparent in a pastel tone.

Examples of polyvalent metal hydroxides that can be used include aluminum hydroxide, calcium hydroxide and the like, which become white oxides upon irradiation with laser light. Examples of the organic aluminum compound include acetylacetone aluminum and the like. Examples of the borate include metal borate salts such as zinc borate, calcium borate, magnesium borate, lithium borate, aluminum borate, sodium borate, manganese borate, and barium borate, and these are anhydrous even if they contain bound water. But good. As silicates, natural mica such as muscovite, phlogovite, biotite, sericite, fluorophlogopite,
Synthetic mica such as fluorinated tetrasilicon mica, zirconium silicate, calcium silicate, aluminum silicate, wollastonite, bentonite, silica, hydrous silica, talc, kaolin,
Clay, silica sand, blast furnace slag, diatomaceous earth and olivine family, garnet family, calcium pyroxene family, semipyroxene family, amphibole family, serpentine family, feldspar family, and various natural silicates belonging to quasi-feldspar family. The phosphates include zinc phosphate, monobasic calcium phosphate, dibasic calcium phosphate, tribasic calcium phosphate, monobasic magnesium phosphate, dibasic magnesium phosphate, tribasic magnesium phosphate, monobasic lithium phosphate, dibasic lithium phosphate, and tribasic phosphate. Lithium, aluminum phosphate, sodium monophosphate, sodium diphosphate, sodium triphosphate, potassium monophosphate, potassium diphosphate, potassium triphosphate, manganese phosphate, manganese ammonium phosphate, zirconyl phosphate, barium phosphate, hydroxide Examples include apatite.
Examples of the oxalates include calcium oxalate and magnesium oxalate. Of these, aluminum hydroxide, zinc borate, calcium phosphates, mica, silica, talc, kaolin, clay, calcium hydroxide, magnesium oxalate, and more preferably aluminum hydroxide, mica, zinc borate. And aluminum hydroxide is particularly preferable. You may use these compounds in mixture of 2 or more types.

The compound which absorbs the laser beam used in the present invention may be an inorganic compound having an absorption peak of infrared absorption spectrum in the range of 900 to 1000 cm ^-1 . This inorganic compound can be used regardless of its absorption intensity if it has an absorption peak in the above range, and is not particularly limited as long as it exhibits a white color by laser light irradiation,
The color of the compound itself preferably has a white color such as a pastel color such as white, reddish white, bluish white, yellowish white, and blackish white, and specific examples thereof include hydroxide. Examples include various inorganic compounds such as aluminum, wollastonite, bentonite, hydrous silica, calcium silicate, talc, kaolin, and clay, but aluminum hydroxide is particularly preferable. You may use these inorganic compounds in mixture of 2 or more types. It should be noted that the white color includes those having transparency such as colorless and transparent and colored and transparent in a pastel tone.

The compound which absorbs the laser beam used in the present invention is an inorganic compound having a small hiding property (no use as a pigment) when the composition for laser marking of the present invention requires transparency. Is preferred. Such an inorganic compound is not particularly limited as long as it exhibits a white color upon irradiation with laser light, but the color of the compound is, for example, white, reddish white, bluish white, yellowish white, blackish white. Those having a white color such as pastel color are preferable, and specific examples thereof include aluminum-containing inorganic compounds such as aluminum hydroxide. It should be noted that the white color includes those having transparency such as colorless and transparent and colored and transparent in a pastel tone.

The proportion of each of the above-mentioned components in the laser marking composition of the present invention is preferably 2 to 70% by weight, more preferably 5 to 70% by weight, based on the total solid content of the composition. 60% by weight, more preferably 1
The range of 0 to 50% by weight and the energy curable resin is preferably 30 to 98% by weight, more preferably 40 to 95% by weight, and further preferably 50 to 90% by weight.
The ratio of the compound that absorbs laser light and the energy ray-curable resin in the composition of the present invention is not particularly limited, but generally, 1 part by weight of the compound is the energy ray-curable resin. It is preferably used in an amount of 0.4 to 50 parts by weight, more preferably 1 to 20 parts by weight.

Other additives may be added to the composition for laser marking of the present invention, if necessary.
Examples of other additives that can be used include colorants, dispersants, flow regulators, release agents, flame retardants, lubricants, light stabilizers, antioxidants, and various fillers other than the inorganic compounds used in the present invention. Materials used in energy ray-curable coatings such as materials. Examples of colorants that can be used in the present invention include carbon black, phthalocyanine, monoazo, disazo, quinacridone, anthraquinone, flavantron, perinone, perylene, dioxazine, condensed azo, azomethine, or various organic pigments of methine type, titanium oxide. , Lead sulfate, zinc oxide, black iron, chrome yellow,
Examples include inorganic pigments such as zinc yellow, chrome vermilion, sage, cobalt purple, ultramarine blue, navy blue, chrome green, and cobalt green. The amount used is such that the viscosity in an E-type viscometer at 60 ° C. is 20 cps or less, and in a range that does not affect the vividness of color development, and is usually 1 w / w% or less in all solid sentences. Used in proportion. Further, as the filler, calcium carbonate, alumina, an inorganic filler other than the inorganic compound that absorbs the laser light of the present invention,
In addition, organic fillers such as polyethylene, polyamide, epoxy resin and guanamine resin can be used.

The composition of the present invention is used by coating it on a substrate. In order to facilitate application to a substrate,
Various auxiliaries can be added. The amount added is 0.1 to 40% by weight of the total solid content in the composition, preferably 0.1.
It is preferably about 3 to 25% by weight. As various auxiliaries, for example, sodium dioctyl sulfosuccinate, sodium dodecylbenzene sulfonate, sodium lauryl alcohol sulfate ester, anionic type such as fatty acid metal salt, oleylamine acetate, aminopropylamine oleate, cationic type such as tetraalkylammonium, Polyethylene glycol derivatives, polyhydric alcohol derivatives, nonionic compounds such as higher fatty acid esters, amino acid, amphoteric ion type dispersants such as betaine compounds, other silicone type, higher alcohol type, fluorine type antifoaming agents, triazole type, Phenol-based and amine-based light stabilizers, stilbene-based and coumarin-based fluorescent dyes, higher fatty acids and their salts, carnauba wax, polyethylene wax, and fluororesin-based lubricants In filler other than the inorganic compound used, titanium dioxide, calcium carbonate, various masking agents typified by alumina. These are not particularly limited and are appropriately selected from various commercially available auxiliaries.

The marking composition of the present invention comprises an energy ray-curable resin, a compound that absorbs laser light, and other fillers, colorants, dispersants, flow regulators, release agents, flame retardants, and light as required. It is prepared by mixing a stabilizer, an antioxidant and the like using a stirrer such as a triple roll, preferably at a temperature of 15 to 30 ° C.

The laser marking article of the present invention is an article having a cured coating of the above laser marking composition on the surface of the article. Examples of the article include bottles, caps, cards, labels or cans. The film thickness of the laser marking composition present on the surface of the article is 3 to 50 μm, preferably 4 to 30 μm, and more preferably 5 to 20 μm.

In order to produce the laser marking article of the present invention, the surface of the article is coated with the above laser marking composition by a spray coating method, and then the coated surface is irradiated with infrared rays, visible rays, ultraviolet rays, electron beams or the like. Energy rays,
Preferably, the composition may be cured by irradiation with ultraviolet rays or electron beams.

Spray coating is a method in which ink is passed under pressure through a nozzle to form fog droplets of several hundred μm or less, and the fog droplets are sprayed onto a substrate for coating. There are two methods of atomization, one is using compressed air, and the other is two methods in which the ink itself is compressed by a pressure pump to atomize. In the present invention, either method can be used. In order to obtain a uniform thin film of 3 to 50 μm in the present invention, the fog droplets obtained by spraying are 0.5 μm to several hundred μm.
m, preferably 1 μm to 100 μm, more preferably 2
μm to 80 μm. In order to obtain such small fog droplets, the viscosity of the ink is the most important factor, and the lower the viscosity of the ink, the smaller fog droplets can be obtained. The viscosity of the ink is 20 cp at 60 ° C with an E-type viscometer.
s or less, preferably a viscosity of 2 with an E-type viscometer at 50 ° C.
The viscosity in an E-type viscometer at 40 ° C. is 20 cps or less. Further, since the liquid composition (ink) of the present invention has a low viscosity, it is suitable for gravure printing which requires low viscosity.

The E-type viscometer referred to here is a kind of rotational viscometer for calculating viscosity and yield value from resistance generated when a disk, cylinder, cone plate, etc. are rotated in ink, and is a relatively small amount. It is generally used because it can be measured by.

To carry out the laser marking method of the present invention, for example, the following may be carried out. That is, the marking composition of the present invention was applied to a molded article to be marked by a spray coating method so that the film thickness after curing would be 3 to 50 μm, and was cured by irradiating with energy rays. After that, by irradiating the surface of the coated article with a laser beam, a white mark having a clear contrast can be obtained. The laser light to be irradiated has an output of 6 J / cm ² or less, preferably 1.0 to 5.5 J / cm ² , and more preferably 1.5 to 5 J / cm ^2.
2 , more preferably 2.0-4.5 J / cm ² pulsed laser, output 5-100 watts or less, preferably 10
Scanning lasers of ˜90 watts or less, more preferably 15-80 watts or less are preferred. The laser used is a carbon dioxide gas laser, a YAG laser,
Examples of the excimer laser include infrared lasers such as TEA carbon dioxide laser.

The substrate of the article to which the liquid composition of the present invention is applied is a metal plate such as aluminum or iron, paper such as vapor-deposited paper, coated paper or synthetic paper, polyester such as polyethylene terephthalate or polybutylene terephthalate, Examples thereof include plastic films made of vinyl chloride, polyethylene, polypropylene and the like, and plastic plates made of these plastics and commonly used plastics such as acrylic resin and ABS resin. The article of the present invention is not particularly limited as long as it is desired to impart a mark with a laser beam, and examples thereof include various containers such as food and medical products such as metal cans, caps and the like of containers and sheets, and packaging. It is used to display the manufacturer name, content display, manufacturing date, lot number, etc. on the surface of sheets, packaging films, cards, labels, bottles, caps, etc.

Depending on the purpose, transparency of the cured film may be required. In this case, it is better not to use a masking agent such as a pigment. If transparency is required, the coating may be performed by a method other than spray coating or gravure printing. Further, in order to improve the adhesion to the substrate, an adhesion improver (for example, Kayamer PM-2
(Manufactured by Nippon Kayaku Co., Ltd.)) may be used.

[0041]

EXAMPLES The present invention will be described in more detail with reference to Reference Examples and Examples, but the present invention is not limited to these Reference Examples and Examples. In the Reference Examples and Examples, parts mean parts by weight.

Reference Example 1 Isobornyl acrylate 30 parts, aluminum hydroxide 3
0 part is passed twice using a triple roll to disperse and obtain color former ink A.

Reference Example 2 Isobornyl acrylate 30 parts Irgacure 1
84 5 parts (Ciba-Geigy photoinitiator), Irgacure 907 2 parts (Ciba-Geigy photoinitiator) and 0.3 parts of metoquinone were dissolved at 80 ° C. and then cooled to 25 ° C. to obtain photoinitiator ink B.

Examples 1 to 5 The above-described color-forming ink and initiator ink were mixed in the composition ratios shown in Table 1 to obtain liquid compositions of the present invention. As shown in Table 1, all of these liquid compositions had a viscosity at 20 ° C. measured by an E-type viscometer of 20 cps or less. These liquid compositions are used as the marking agent of the present invention as an airless spray coater (Cross cut nozzle type: 06 /
When the aluminum substrate was coated with 16 ″ spray time: 50 msec), the marking (ink) was well atomized and a coated film having a uniform coating was obtained. This was irradiated with ultraviolet rays from a high pressure mercury lamp. The marking agent was cured to obtain a test piece having a film thickness of 10 to 15 μm after curing.The test piece was provided with a pulse-type carbon dioxide gas laser irradiator (manufactured by Laser Technics, BLAZAR6000 energy density 3 J /
cm ² ), a clear white mark was obtained when irradiated with laser light. Table 2 shows the water resistance, hot water resistance, and heat resistance test results of the marked test pieces.

Examples 6 to 7 The above color-forming inks were mixed in the composition ratios shown in Table 1 to obtain liquid compositions of the present invention. As shown in Table 1, these liquid compositions all had a viscosity of 20 cp at 60 ° C. measured by an E-type viscometer.
It was s or less. When these liquid compositions were applied as a marking agent of the present invention on an aluminum substrate with an airless spray coater (Crosscut nozzle type: 06/16 "spray time: 50 msec) manufactured by Nordson Co.,
The marking (ink) was well atomized, and a coated product having a uniform coating film was obtained. The marking agent is cured by irradiating it with an electron beam of 6 mega rat (CB175 / 15 / 180L manufactured by Iwasaki Electric Co., Ltd.), and the film thickness after curing is 10 to 1
A test piece of 5 μm was obtained. A pulse type carbon dioxide laser irradiation machine (manufactured by Laser Technics, BLAZA
When a laser beam was irradiated using R6000 energy density of 3 J / cm ² ), a clear white mark was obtained. Table 2 shows the water resistance, hot water resistance, and heat resistance test results of the marked test pieces.

Materials C to J in Table 1 are the following acrylates. C: pentaerythriacrylate D: trimethylolpropane triacrylate E: epichlorohydrin-modified 1,6 hexanediol diacrylate F: bisphenol A epoxy resin (R- manufactured by Nippon Kayaku Co., Ltd.
114) G: Ethylene oxide-modified trimethylpropanone triacrylate H: Neopentyl glycol diacrylate I: Isobornyl acrylate J: Dicyclopentanyl acrylate

[0047]

[Table 1] Table 1 Examples A B C D E F G H I J Viscosity 1 60 37.3 10 30 13 2 60 37.3 10 30 11 3 60 37.3 10 30 12 4 60 37.3 10 10 20 15 5 60 37.3 10 30 10 6 60 10 30 11 7 60 10 30 11

[0048]

[Table 2] Table 2 Examples Transparency Color development Water resistance Hot water resistance Heat resistance Adhesion 〇 〇 〇 〇 〇 6 6 〇 〇 〇 〇 〇 〇 〇 7 〇 〇 〇 〇 〇 〇 〇

The evaluation results shown in Table 2 were measured by the following evaluation methods. (1) Transparency: It was visually judged whether or not the metal color of the aluminum test piece was maintained. ◯: The coating film is transparent and the aluminum base can be clearly confirmed. Δ: The coating film is semi-transparent and the metallic color of the aluminum base is visible. X: The coating film is milky white and the metallic color of the aluminum base cannot be seen at all. (2) Coloring property: The marking portion of the test piece was visually judged. ○: A clear mark can be confirmed. Δ: The mark is somehow visible. X: The mark cannot be read at all. (3) Water resistance: Marked test pieces in cold water at 5 ° C
After soaking for a week, wipe off the water on the surface and visually check the mark condition. ○: A clear mark can be confirmed. Δ: The mark is somehow visible. X: The mark cannot be read at all.

(4) Hot water resistance: After the marked test piece was immersed in warm water at 63 ° C. for 1 hour, the surface water was wiped off and the state of the mark was visually judged. ○: A clear mark can be confirmed. Δ: The mark is somehow visible. X: The mark cannot be read at all. (5) Heat resistance: When the marked test piece was left in an atmosphere of 210 ° C. for 10 minutes, the state of the coating film and the mark portion was visually judged. ◯: There is no abnormality such as cracks in the coating film, and clear marks can be confirmed. Δ: The coating film is cracked, but the mark is manageable. X: The coating film is peeled off, and the mark cannot be read at all. (6) Adhesion: Cuts are made in a grid pattern that penetrates the coating film on the test piece and reaches the aluminum substrate, and an adhesive tape is peeled off over the grid pattern to show the state of adhesion of the coating film after peeling. It was visually judged. 〇: There is slight peeling at the intersection of the cuts, but there is no peeling at every glance. Δ: There is peeling at the intersection of cuts, and the area of the defective portion is 5 to 15% of the area of the entire square. X: The area of peeling is 65% or more of the total square area.

From Table 2, it can be seen that the marking composition of the present invention is excellent in adhesion to metal and transparency, and is also excellent in color developability, water resistance, hot water resistance and heat resistance.

[0052]

The marking composition has a low viscosity and is suitable for spray coating and gravure printing, and develops a clear white color by irradiation with a laser beam, and a clear white color, and is more robust. Provided are a marking composition having excellent properties, adhesion to a metal, and transparency, and a laser marking method using the composition.

Claims (20)

[Claims] 1. A liquid composition for laser marking, which contains an energy ray-curable resin and a compound that absorbs laser light as essential components and has a viscosity of 20 cps or less as measured by an E-type viscometer at 60 ° C. 2. The energy ray curable resin is a resin having a viscosity of 20 cps or less measured by an E-type viscometer at 60 ° C.
Liquid composition for laser marking. 3. The energy ray curable resin comprises an acrylate resin having a cyclic structure in the molecule and an energy ray curable resin other than the acrylate resin, and one or both of the resins has an E-type viscosity at 25 ° C. 50c by viscometer
The liquid composition according to claim 2, which has a ps or less. 4. An acrylate resin having a cyclic structure in the molecule is a dicyclopentanyl ring, a dicyclopentenyl ring,
Isobornene ring, morpholine ring, benzene ring, cyclohexane ring, cyclohexene ring, piperidine ring, naphthalene ring, piperazine ring, pyrimidine ring, furan ring, imidazole ring, imidazoline ring, imidazolidine ring, pyridine ring, picoline ring, quinazoline ring, anthracene ring The liquid composition according to claim 3, which is an acrylate resin having a ring or a fluorene ring. 5. The liquid according to claim 3, wherein the acrylate resin having a cyclic structure in the molecule and having a viscosity of 50 cps or less measured by an E-type viscometer at 25 ° C. is a monoacrylate resin having a cyclic structure in the molecule. Composition. 6. A monoacrylate having a cyclic structure in the molecule, wherein the monoacrylate resin has one or more of dicyclopentanyl ring, dicyclopentenyl ring, isobornene ring, morpholine ring, benzene ring and cyclohexane ring. The liquid composition according to claim 5, which is a resin. 7. A monoacrylate resin having a cyclic structure in the molecule is dicyclopentanyl acrylate, dicyclopentanyl methacrylate, dicyclopentanyloxyethyl acrylate, dicyclopentanyloxyethyl methacrylate, isobornyl. Acrylate, isobornyl methacrylate, morpholine acrylate,
The liquid composition according to claim 5, which is phenoxydiethylene glycol acrylate or cyclohexyl acrylate. 8. The laser marking according to claim 1, wherein the compound that absorbs laser light is a hydroxide of a polyvalent metal, an organoaluminum compound, borates, silicates, phosphates or oxalates. Composition. 9. A compound that absorbs laser light is 900 to 1
The composition for laser marking according to any one of claims 1 to 7, which is an inorganic compound having an absorption peak of infrared absorption spectrum in a range of 000 cm ^-1 . 10. The laser marking composition according to claim 9, wherein the inorganic compound having an absorption peak in the infrared absorption spectrum in the range of 900 to 1000 cm ⁻¹ is aluminum hydroxide. 11. The ratio of the energy ray curable resin to the total solid content of the laser marking composition is 30 to 98.
% By weight, and the ratio of compounds that absorb laser light is 2
The composition for laser marking according to any one of claims 1 to 10, wherein the composition is about 70% by weight. 12. A laser marking article having a cured coating of the laser marking composition according to any one of claims 1 to 11 on the surface of the article. 13. The laser marking article according to claim 12, wherein the article is a bottle, a cap, a card, a label or a can. 14. The laser marking article according to claim 12, wherein the cured film has a thickness of 3 to 50 μm. 15. In manufacturing the article according to any one of claims 12 to 14, the surface of the article is irradiated with energy rays after the composition for laser marking according to any one of claims 1 to 11 is applied by a spray coating method. A method for producing an article for laser marking, comprising: 16. The method for producing an article for laser marking according to claim 14, wherein the energy rays are ultraviolet rays or electron rays. 17. A laser marking method, which comprises irradiating a laser beam to a cured coating layer formed on the surface of the article according to claim 12. 18. The laser marking method according to claim 17, wherein the laser light is an infrared laser. 19. The laser marking method according to claim 17, wherein the infrared laser light is a far infrared laser. 20. The energy of laser light is 1.0 to 6.
The laser marking method according to any one of claims 17 to 19, wherein the laser marking is 0 J / cm ² .