JPH09254552A - Laser marking composition and article obtained by using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form an excellent laser marking film well forming a color by laser beam by using a compsn. prepared by adding an aq. normal temp. drying type emulsion compounded with a polyhydrazide crosslinking agent, a color former and a coupler to a carbonyl group-containing polymer emulsion. SOLUTION: As aq. normal temp. drying type emulsion, a carbonyl group- containing polymer emulsion obtained by emulsifying and polymerizing a carbonyl group-containing unsaturated monomer and a radical polymerizable unsaturated monomer in the presence of a nonionic and/or anionic surfactant is used. A laser marking compsn. is prepared by mixing a color former and a coupler with the aq. normal temp. drying type emulsion. A laser marking article is obtained by coating a base material with the laser marking compsn. to form a laser marking film layer and crosslinking this film layer. By this constitution, the laser marking article forming a color by laser beam to impart a good mark and excellent in water resistance, chemical resistance and solvent resistance is obtained.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a laser marking composition and an article obtained by using the same.

[0002]

2. Description of the Related Art Conventionally, products such as food containers, medical product containers, cosmetic containers, packaging materials, electronic parts, etc., usually have information such as a production lot number, a production date, a production factory, and a type, written in letters, Marking is done with symbols, marks, figures, bar codes, etc. As a marking method, in recent years, it is possible to mark articles of various shapes in real time, and since it has advantages such as high-speed printing and fine marking, the laser marking method has been used. There is.

In this system, a color-forming layer coating liquid containing a color-developing agent, a color-developing agent and a binder as a main component is applied to a substrate, and then a laser is irradiated to a necessary portion to react the color-developing agent with the color-developing agent. The mark is formed by coloring that portion (see JP-A-7-228057 and JP-A-7-257042). However,
The binder component used in the method described in the above publication is substantially an aqueous polyvinyl alcohol solution, an acrylic emulsion (ethyl acrylate, emulsion containing acrylonitrile and butadiene as a main monomer component, methyl methacrylate, 2-ethylhexyl acrylate and styrene. The laser marking coating formed by the method described in the above publication is a non-crosslinking type binder component (emulsion which is a main monomer component), and has a water resistance, oil resistance, solvent resistance, weather resistance, etc. Since the performance is not sufficient, there is a drawback that it cannot be used for outdoor articles that require durability and articles that come into contact with water, chemicals and the like. Laser marking coatings are usually made of plasticizers, oils, alcohols, and other substances that erase the marks in the colored areas and make the marks unreadable, and the uncolored areas discolor, making it difficult to distinguish between the marks and their surroundings. It has the drawback of being clear.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides good color development by a laser beam, water resistance, chemical resistance, solvent resistance,
It is intended to develop a composition capable of forming a laser marking film having excellent weather resistance and the like.

[0005]

Means for Solving the Problems The inventors of the present invention have completed the present invention as a result of intensive studies to solve the above problems. That is, the present invention provides: (I) Aqueous normally dry emulsion prepared by blending a carbonyl group-containing emulsion with a polyhydrazide crosslinking agent,
1. A composition for laser marking, which comprises (II) a color former and (III) a color developer; The carbonyl group-containing emulsion contains diacetone acrylamide and / or diacetone methacrylamide at 2 to 30% by weight, and at least one selected from acrylic acid, methacrylic acid, acrylamide and methacrylamide.
0% to 1.5% by weight of total monomers, 0% styrene
~ 30% by weight, 0 to 10% by weight of a hydroxyl group-containing monomer,
And a polymerizable monomer mixture (1) containing 38.5 to 98% by weight of a monomer mixture other than the above, in which the SP value of the monomer mixture is 8.0 to 9.3, is 0 based on the polymerizable monomer mixture (1). 1. The above-mentioned composition for laser marking, which is obtained by emulsion polymerization in the presence of 1 to 6.0% by weight of a nonionic and / or anionic surfactant; 3. The laser marking composition as described above, wherein the polyhydrazide crosslinking agent is an adipic acid dihydrazide compound; It is intended to provide a laser marking article having a laser marking crosslinked coating layer formed from the above laser marking composition and a clear coating for topcoat on the surface.

Hereinafter, the composition for laser marking and the laser marking article of the present invention will be described in more detail.

Aqueous normally dry emulsion (I) : As an aqueous normally dry emulsion, a carbonyl group-containing unsaturated monomer (A) and other radical polymerizable compounds capable of radical copolymerization with the monomer (A) A carbonyl group polymer emulsion obtained by emulsion polymerization of the unsaturated monomer (B) in the presence of a nonionic and / or anionic surfactant can be used.

The carbonyl group-containing unsaturated monomer (A) is a monomer having at least one aldehyde group or keto group and one radically polymerizable double bond in one molecule, that is, a polymerized polymer. Possible mono-olefinically unsaturated aldehyde compounds and keto compounds can be used. As typical examples thereof, for example, diacetone (meth) acrylamide, diacetone (meth) acrylate, acrolein, formyl styrene, 2-hydroxypropyl (meth) acrylate acetyl acetate,
Examples thereof include vinyl alkyl ketone. Of these, diacetone (meth) acrylamide is preferred.

The other radically polymerizable unsaturated monomer (B) has a double bond capable of radical polymerization reaction with the above monomer (A) and does not substantially react with a carbonyl group. There is no particular limitation as long as it is a conventionally known one and can be used. In particular,
For example, methyl (meth) acrylate, ethyl (meth)
C of (meth) acrylic acid such as acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, lauryl (meth) acrylate, cyclohexyl (meth) acrylate, etc.
1-24 alkyl or cycloalkyl esters and the like;
Methoxybutyl (meth) acrylate, methoxyethyl (meth) acrylate, ethoxybutyl (meth) acrylate, etc. Acrylic acid or methacrylic acid C2-C18 alkoxyalkyl esters, etc .; Acrylonitrile, methacrylonitrile, etc. nitriles Compounds; aromatic unsaturated compounds such as vinyltoluene and styrene; hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, diethylene glycol mono (meth)
Hydroxyl group-containing monomers such as acrylate and ε-caprolactone-modified (meth) acryl hydroxyethyl; nitrogen-containing unsaturated compounds such as (meth) acrylamide and vinylpyridine; olefin compounds such as ethylene and propylene; vinyl chloride and vinyl acetate Etc. can be mentioned.

Among the above-mentioned monomer components, diacetone acrylamide and / or diacetone methacrylamide are contained in an amount of 2 to 30% by weight, and at least one monomer selected from acrylic acid, methacrylic acid, acrylamide and methacrylamide is added in total. 0 to 1.5% by weight, 0 to 30% by weight of styrene, 0 to 10% by weight of a hydroxyl group-containing monomer, and a monomer mixture (1) other than the above in which the SP value of the monomer mixture is 8.0 to 9.3. 38.5-98
A blend of a polymerizable monomer in a weight percentage is preferable because it is excellent in storage stability of the laser marking composition and water resistance, oil resistance, solvent resistance and weather resistance of the crosslinked coating.

Here, the "SP value" is an abbreviation for solubility parameter and represents a measure of intermolecular interaction of liquid molecules. The SP value of the polymerizable monomer in the present specification is J. Paint Technology, vol.42, 176.
The one described in (1970) was adopted. S of monomer mixture
The P value is calculated using the following formula (1).

SP = SP1 × fw1 + SP2 × fw2 + ... + SPn × fwn (1) In the above formula (1), SP1, SP2 ... SPn are SP values of the respective monomers, and fw1, fw2 ... fwn are respectively The weight fraction of the total monomer is shown.

Surfactants which can be used in emulsion polymerization of the monomers (A) and (B) include:
A nonionic anionic surfactant having a polyoxyethylene or polyoxypropylene chain between a hydrophobic part and a hydrophilic anionic part is preferable. When such a surfactant is attached to the particle surface, there is a hydrophilic nonionic surface-active portion between the polymer phase of the particle and the anion in water, and the anion promotes crosslinking on the particle surface during storage. Prevent you from doing so. Examples of such surfactants include Newcol 560SN, Newcol 560SF, Newcol 707.
SF, Newcol 861SE, Newcol 1305SN (all manufactured by Nippon Emulsifier), Hitenol series (manufactured by Daiichi Kogyo Seiyaku), Latemur WX, Emal NC-35, Rebenol WZ (all manufactured by Kao) and the like can be mentioned. The amount of these surfactants used is generally 0.1 to 6% by weight, preferably 0.2 to 5%.
% By weight. In addition to the above surfactants, nonionic surfactants can also be used. Further, other anion activators can be used in combination as long as the amount is small.

The emulsion polymerization can be carried out according to a method known per se.

The polyhydrazide crosslinking agent added to the obtained emulsion is a compound having two or more hydrazide groups in one molecule. Specifically, for example, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide,
C1 to C20 aliphatic carboxylic acid dihydrazides such as glutaric acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, eicosane diacid dihydrazide; carbonic acid dihydrazide such as carbonic acid dihydrazide; phthalic acid dihydrazide, terephthalic acid dihydrazide, trimellitic acid trihydrate An aromatic polyhydrazide such as hydrazide; bissemicarbazide and polyacrylic acid polyhydrazide can be mentioned. Of these, aliphatic carboxylic acid dihydrazides and adipic acid dihydrazide are preferable because they have appropriate water solubility and the composition has good storage stability.

These polyhydrazine crosslinking agents are usually
The hydrazide group can be used in a proportion of 0.1 to 2.0 equivalents, preferably 0.2 to 1.2 equivalents, relative to 1 equivalent of carbonyl groups in the emulsion composition.

Aqueous normally dry emulsions generally range from about 20 to.
It can have a solids content in the range of 70% by weight, preferably about 40-60% by weight.

Coloring agent (II): As the coloring agent which can be blended in the composition of the present invention, those which are usually used in heat-sensitive recording materials can be used. Specific examples thereof include 3,3'-bis ( p-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (p-dimethylaminophenyl) -3-
(1,2-dimethylindol-3-yl) phthalide,
3,3′-bis (1,2-dimethylindol-3-yl) -5-dimethylaminophthalide, 3-p-dimethylaminophenyl-3- (1-methylpyrrol-3-yl) -6-diethylamino Triallyl methane phthalide dyes such as phthalide; 4,4'-bis-dimethylaminobenzhydryl benzyl ether, diphenyl methane dyes such as N-halophenyl leuco auramine; thiazine dyes such as benzoyl leuco methylene blue; 3 −
Spiro dyes such as methyl-naphtho (6'-methoxybenzo) spiropyran and 3-benzyl-spiro-dinaphthopyran; lactam dyes such as rhodamine-B-anilinolactam and rhodamine-B- (o-chloroanilino) lactam; 3 -Diethylamino-7- (o-fluoroanilino) fluorane, 3-dimethylamino-7- (o
-Fluoroanilino) fluorane, 3-diethylamino-7- (o-chloroanilino) fluorane, 3-diethylamino-7- (p-chloroanilino) fluorane, 3
-Diethylamino-7-dibenzylaminofluorane,
3- (N-cyclohexyl-N-methylamino) -6
Methyl-7-phenylaminofluorane, 3-diethylamino-6-methyl-7-phenylaminofluorane,
Fluorane dyes such as 3-dibutylamino-6-methyl-7-phenylaminofluorane and 3-diethylaminobenzo [a] fluorane; 3,6-bis (dimethylamino) fluorene spiro (9,3 ′)-6 ′ -Dimethylaminophthalide, 3,6-bis (dimethylamino) fluorenspiro (9,3 ')-6'-pyrrolidinophthalide, 3-dimethylamino-6-diethylaminofluorenspiro (9,3')-6 Fluorene dyes such as ′ -pyrrolidinophthalide; and the like. Of these, fluoran dyes are preferred.

Developer (III): As the developer that can be blended in the composition of the present invention, those commonly used in heat-sensitive recording materials can be used. Specific examples thereof are 4,4'- Sulfonyl diphenol, bis- (3-allyl-4-hydroxyphenyl) sulfone, 2,2 ', 6,6'-
Tetramethyl-4,4'-sulfonyldiphenol,
2,2 ', 6,6'-Tetrabromo-4,4'-sulfonyldiphenol, 4,4'-isopropylidenediphenol, bis- (p-hydroxyphenyl) -methane, 1,1-bis- (p Bisphenols such as -hydroxyphenyl) -cyclohexane; monophenols such as p-octylphenol, p-phenylphenol, 4- (4'-isopropoxyphenyl) sulfonylphenol; benzyl p-hydroxybenzoate, 4-
Dimethyl hydroxyphthalate, diethyl 5-hydroxyisophthalate, 3,5-di-tert-butylsalicylic acid,
Aromatic carboxylic acid derivatives such as salicylic acid and benzyl β-hydroxynaphthalenecarboxylate; polysalt metal salts of carboxylic acids; novolak phenolic resins, activated clay, acid clay, attapulgite, inorganic acid substances such as aluminum silicate and the like. Bisphenols are particularly preferred. These may be used alone or in combination of two or more.

Laser marking composition: The laser marking composition of the present invention basically comprises the above-mentioned aqueous normally dry emulsion (I), a color former (II) and a color developer (III). Can be prepared by mixing. The use ratio of the color former (II) and the color developer (III) in that case can be appropriately changed according to the types of the color former and the color developer used, and is not particularly limited,
Generally, the developer (III) per 1 part by weight of the color developer (II)
It can be in the range of 1 to 50 parts by weight, preferably about 1.5 to 10 parts by weight. Further, the proportion of the color former (II) and the developer (III) in the total solid content in the composition of the present invention is 5 to 30% by weight, preferably 10 to 25% by weight of the color former (II), And the color developer (II) is 10-60
It may be in the range of wt%, preferably 20 to 50 wt%.

In order to increase the sensitivity to laser, the composition for laser marking of the present invention may contain, if necessary, an inorganic compound which absorbs laser light as a recording sensitivity improving agent. Specific examples of such a recording sensitivity improver include aluminum hydroxide, wollastonite, bentonite, mica (white mica, gold mica),
Various inorganic compounds such as silicate minerals such as calcium silicate, talc, kaolin, clay and fayalite, horn blend, and albite are included. Aluminum hydroxide, white mica, wollastonite and the like are particularly preferable. These inorganic compounds may be used alone or in combination of two or more, and the compounding ratio thereof is preferably 1 to 50 parts by weight, more preferably about 1.5 to 1 part by weight per 1 part by weight of the color former (II).
It can be used within the range of 0 parts by weight. Further, these recording sensitivity improvers are preferably 5 to 40% by weight, more preferably 10 to 30% by weight, based on the solid content of the composition.
It can be used within the range of.

The laser marking composition of the present invention may contain various auxiliaries, if necessary, in addition to the above components in order to facilitate coating on a substrate. Examples of the auxiliary agents that can be mixed include dispersants such as sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, sodium lauryl alcohol sulfate, and fatty acid metal salts; UV absorbers such as benzophenone-based and triazole-based; oxidation. Hiding agents such as titanium; other antifoaming agents, viscosity modifiers, fluorescent dyes, coloring agents and the like. Also, higher fatty acid amides such as stearic acid amide; animal waxes such as beeswax and ceramic wax; vegetable waxes such as carnauba wax; mineral waxes such as montan wax;
Paraffin wax, petroleum wax, higher fatty acid esters, chlorinated paraffin, synthetic paraffin, acetoacetic acid anilides, diphenylamines, carbazoles, fatty acid anilides; carboxylic acid esters such as dimethyl terephthalate and diphenylphthalate; benzenesulfonic acid anilide, etc. Sulfonic acid amides; sulfonic acid esters such as p-toluenesulfonic acid phenoxyethyl ester and benzenesulfonic acid phenyl ester; diphenyl such as bis- (4-allyloxyphenyl) sulfone and bis- (4-pentylphenyl) sulfone Sulfones; Naphthol derivatives such as 1-benzyloxynaphthalene and 2-benzoyloxynaphthalene; Urea derivatives such as N-stearylurea; 4-
Diketone compounds such as acetylacetophenone and octadecane-2,17-dione; ethers such as 1,2-m-cresyloxyethane can be appropriately used as the sensitizer.

The laser marking composition of the present invention can be prepared, for example, as follows: water or a solvent containing water as a main component among color formers, color developers, recording sensitivity improvers and the like. For what needs to be distributed in
Using a dispersing machine such as a ball mill, an attritor, or a sand grinder, the respective components are treated together or separately in water or a water-containing solvent containing a dispersant such as polyvinyl alcohol to obtain a dispersion liquid. The average particle size of each component after dispersion can be usually about 2 μm or less, preferably about 1 μm or less. Next, the composition for laser marking of the present invention is obtained by mixing the dispersion (I) with the emulsion (I). The solid content of the composition is 40 to 70% by weight, preferably about 50 to 65% by weight.

Laser marking article: The laser marking article of the present invention is left at room temperature after the composition for laser marking obtained as described above is applied (printed) on a substrate to form a laser marking coating layer. Or by heating to crosslink the laser marking coating layer. The substrate to which the composition is applied is not particularly limited as long as it requires marking, and for example, a predetermined portion such as a food container, a packaging material, an electronic component, or the like for sticking to these. Articles such as a label substrate may be mentioned. As the label substrate,
Papers such as paper and synthetic paper, synthetic resin films, plastics, metal vapor-deposited papers and synthetic papers, metal vapor-deposited films, metals, woods, etc. are appropriately used according to the application.

The composition for laser marking may be applied directly to a substrate, or may be applied to a substrate which has been subjected to surface treatment or undercoating in advance. The coating can be performed using a suitable coating device such as a roll coater, a gravure coater, a micro gravure coater, a knife coater, and a spray coater. The thickness of the coating obtained after coating and cross-linking can be generally 1 to 8 μ, and if it is less than 1 μ, the color development due to laser irradiation is inferior and at the same time the coating film is easily peeled off. And label aptitude tend to decrease.
Drying may be performed at room temperature depending on the coating conditions such as line speed, but usually about 60 to about 150 ° C.
It is preferable that the heating is performed for about 1 to about 60 seconds.

In the laser marking article of the present invention, a clear coating composition for top coat can be applied (printed) on the surface of the coating of the above laser marking. As a clear coating composition for a top coat, a conventionally known top clear composition for a laser marking coating or a coating, a non-crosslinked or crosslinked resin used in printing or the like is dissolved or dispersed in water or an organic solvent. It is possible to use a clear resin liquid or the like. Among these, a lacquer-clear resin liquid using an organic solvent as a medium is particularly preferable because it is easy to dry and the performance is excellent as compared with the aqueous non-crosslinked type.

Examples of the lacquer-clear resin liquid include cellulose derivatives (nitrocellulose, acetylbutyl cellulose, etc.), acrylic resins, alkyd resins,
Examples thereof include silicone resin, vinyl resin, vinyl chloride / vinyl acetate copolymer, polyvinyl butyral, polyurethane resin, fluororesin, epoxy resin, polyamide resin and the like. These resins can be used alone or in combination of two or more. Further, the above-mentioned aqueous normally dry emulsion (I) can be used as the clear resin liquid. If necessary, for example, in the clear resin liquid,
A leveling agent, a slipperiness imparting agent, an antifoaming agent and the like can be added. The method for applying (printing) the clear resin liquid is not particularly limited, and for example, a roll coater, a gravure coater, a microgravure coater, a spray coater, or the like can be used. The film thickness is generally 3 to
It can be 10 μ.

When the coloring layer formed on the marking article thus formed is irradiated with a laser beam, the irradiated portion is heated, and the developer and the coloring agent react with each other to develop a color and mark. The amount of energy of the laser to be irradiated is not particularly limited, but considering the possibility of breaking the coating film,
It is preferably 1.8 J (joule) / cm ² or less. on the other hand,
The lower limit of irradiation energy required for color development is unknown because there is no device that generates low energy, but 0.4 J / cm
^{Even with 2} energies, sufficient color is developed. Therefore, the irradiation energy for color development is generally 0.4 to 1.8 J.
/ Cm ² , especially 0.45 to 1.4 J / cm ² is suitable. Further, the laser to be irradiated is preferably a pulsed laser or a scanning laser, and the type of laser may be, for example, any of a gas laser, an excimer laser, and a semiconductor laser. Examples include gas lasers, mixed gas lasers, YAG lasers and ruby lasers.

As a method of partially irradiating a desired shape with a laser beam, a method of irradiating the coating film with a laser beam through a metal mask and irradiating the coating film with a laser beam corresponding to the shape of the void portion of the metal mask, There is a method of inputting a desired desired shape to a computer and irradiating a laser beam according to the shape in a so-called one-stroke writing manner. When the color-developing layer is irradiated with a laser beam, the temperature of that part rises and the color is developed by the melt-mixing of the color-forming components in the laser marking coating layer, and letters and figures having a clear desired shape appear. The color change due to this irradiation can be performed instantaneously because the energy density of the laser light is high.

Labels as laser marking articles of the present invention include papers, papers such as synthetic papers as base materials, synthetic resin films, plastics, metal vapor-deposited papers and synthetic papers, metal vapor-deposited films, A label base material that appropriately uses metals and the like according to the application can be produced by forming a color-forming layer and a clear coating layer for a top coat, if necessary, by the above-mentioned method, and as a use of the obtained label. Is applicable to all fields conventionally used, but fields such as foods, pharmaceuticals, toiletries, publications, electronic and electric parts are particularly preferable.

The packaging material as the laser marking article of the present invention includes paper, paper such as synthetic paper as a base material, synthetic resin film, plastics, metal vapor-deposited paper and synthetic paper, metal vapor-deposited. Various kinds of commonly used packaging materials such as boxes, wrapping paper, packages, etc., in which films, metals, glass, wood, etc. are appropriately used according to the application, and laser marking coating layers and top coats as required by the method described above. Those having a clear protective coating layer for use therein may be mentioned. The use of the packaging material is directed to all fields conventionally used, but food, pharmaceuticals,
The fields of toiletries, publications and electronic / electrical components are particularly preferred.

Further, the container as the laser marking article of the present invention comprises glass, plastic, and metal as a base material, and a laser marking coating layer and, if necessary, a top coat on the base material by the above-mentioned method. Those provided with a clear coating layer for use are included. As food containers, bottles of alcoholic beverages and soft drinks, retort food containers, instant food containers, cosmetics containers, pharmaceutical containers,
Markings according to the invention are possible for all conventionally used containers, such as toiletry products.

[0033]

The present invention will be described below in more detail with reference to examples. Unless otherwise noted, all parts and percentages are parts by weight and percentages by weight.

Production Example of Aqueous Normal Dry Emulsion 242 parts of deionized water and Ne in a 2-liter four-necked flask.
2.4 parts of wcol 707SF (Daiichi Kogyo Seiyaku Co., Ltd., solid content 30%) was added, and the temperature was maintained at 80 ° C. after purging with nitrogen. Immediately before dropping this pre-emulsion, 0.7 part of ammonium persulfate was added, and 352 parts of deionized water, 67 parts of diacetone acrylamide, 3.2 parts of acrylic acid, and 118.2 of styrene.
Parts, methyl methacrylate 120 parts, 2-ethylhexyl acrylate 120 parts, n-butyl acrylate 24
A pre-emulsion of 3 parts, 64.5 parts of Newcol 707SF and 1.3 parts of ammonium persulfate was added dropwise over 3 hours. From 30 minutes after the completion of dropping, a solution of 0.7 parts of ammonium persulfate dissolved in 7 parts of deionized water was added dropwise for 30 minutes, and kept at 80 ° C. for 2 hours to obtain an emulsion.
The emulsion had a SP value of 8.5 for the monomer mixture (120 parts of methyl methacrylate / 2,120 parts of 2-ethylhexyl acrylate / 243 parts of n-butyl acrylate).
9. The solid content was 51.2%. Then, to the obtained emulsion, add adipic acid dihydrazide to P with ammonia water.
After adjusting H to 8-9, it was blended so as to be 1.0 equivalent to 1 equivalent of carbonyl group of the emulsion to obtain an aqueous normally dry emulsion.

Production Example of Aqueous Normal Dry Emulsion An emulsion was obtained in the same manner as the above emulsion, except that the pre-emulsion to be dropped had the following monomer composition. [Monomer component (352 parts deionized water, 100 parts diacetone acrylamide, 8 parts methacrylic acid, 201 parts styrene, 67 parts methyl methacrylate, 294 parts 2-ethylhexyl methacrylate, Newcol 707SF64.
5 parts, ammonium persulfate 1.3 parts)] The emulsion is a monomer mixture (methyl methacrylate 67 parts / 2-ethylhexyl acrylate 294 parts).
Had an SP value of 8.11 and a solid content of 51.4%. Next, adipic acid dihydrazide was added to the obtained emulsion with ammonia water to adjust the pH to 8 to 9, and then compounded so as to be 1.0 equivalent to 1 equivalent of carbonyl groups of the emulsion to obtain an aqueous normally dry emulsion. .

Production Example of Aqueous Normal Dry Emulsion A 2 liter four-necked flask was charged with 242 parts of deionized water and Ne.
0.6 part of wcol 707SF (Daiichi Kogyo Seiyaku Co., Ltd., solid content 30%) was added, and the temperature was maintained at 80 ° C. after purging with nitrogen. Immediately before dropping the pre-emulsion having the following monomer composition, 0.8 part of ammonium persulfate was added, and the pre-emulsion was dropped over 3 hours. [Monomer component (328 parts of deionized water,
Diacetone acrylamide 39 parts, acrylic acid 4 parts,
Styrene 109 parts, methyl methacrylate 316 parts, 2
-114 parts of ethylhexyl acrylate, 184 parts of n-butyl acrylate, 15 parts of 2-hydroxyethyl acrylate, 52 parts of Newcol 707SF, 1.6 parts of ammonium persulfate)] 30 minutes after dropping, 10 parts of 0.5 parts of ammonium persulfate are deionized. The solution dissolved in water was added dropwise for 30 minutes, and then kept at 80 ° C. for 2 hours to obtain an emulsion. The emulsion is a monomer mixture (methyl methacrylate 31
6 parts / 2-ethylhexyl acrylate 114 parts / n-
Butyl acrylate (184 parts) had an SP value of 8.80 and a solid content of 54.8%. Then, add adipic acid dihydrazide to the obtained emulsion with ammonia water to adjust the pH to 8
After adjusting to -9, the emulsion was obtained by blending so as to be 1.0 equivalent to 1 equivalent of carbonyl group of the emulsion.

Production Example of Aqueous Normal Dry Emulsion 200 parts of deionized water was placed in a 2-liter four-necked flask, and the temperature was maintained at 80 ° C. after purging with nitrogen. A pre-emulsion having the following monomer composition was added dropwise over 3 hours. [Monomer (285 parts deionized water, 50 parts diacetone acrylamide, 145 parts styrene, 50 methyl methacrylate)
Part, 2-ethylhexyl acrylate 247 parts, 2-hydroxyethyl acrylate 8 parts, Newcol 707SF52
Part, ammonium persulfate 2.5 parts)] After 30 minutes of dropping, a solution of 0.5 parts of ammonium persulfate in 10 parts of deionized water was added dropwise for 30 minutes, and then kept at 80 ° C. for 2 hours to obtain an emulsion. It was The emulsion is a monomer mixture (methyl methacrylate 50
Part / 2-ethylhexyl acrylate 247 parts) SP
The value was 8.10 and the solid content was 49.5%. Next, malonic acid dihydrazide was adjusted to a pH of 8 to 9 with aqueous ammonia, and the resulting emulsion was mixed in an amount of 1.0 equivalent to 1 equivalent of carbonyl groups in the emulsion to obtain an emulsion.

In the above emulsion, the SP values of methyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate and n-butyl acrylate are 9.23, 7.87, 7.85 and 8.63, respectively.

Preparation Example of Coloring Agent Dispersion (a) 3-A mixture of 30 parts of diethylamino-7- (o-fluoroanilino) fluorane, 20 parts of 25% polyvinyl alcohol and 50 parts of deionized water was applied using a sand grinder. After being treated for 2 hours, the average particle size was dispersed to about 0.8 μm to obtain a color developer dispersion (a). The dispersion (a) has a solid content of 3
5% and the color former concentration was 30%.

Production Example of Coloring Agent Dispersions (b) to (e) As a coloring agent, 3-diethylamino-7- (o-chloroalinino) fluorane, 3-dibutylamino-6-methyl-7-phenylaminofluorane, 3 , 3'-bis (p
-Dimethylaminophenyl) -6-dimethylaminophthalide or 3-diethylamibenzo [a] fluorane was used in the same manner as in the production example of (a) above, but in order (b) to (e). Was manufactured. The dispersions (b) to (e) had a solid content of 35% and a color former concentration of 30%.

Production Example of Developer Dispersion (f) Bis- (3-allyl-4-hydroxyphenyl) sulfone 40 parts, 40% by weight acrylic emulsion (glass of resin containing ethyl acrylate, acrylonitrile and butadiene as main components) A mixture of 12.5 parts of emulsion having a transition temperature of about -10 ° C and 47.5 parts of deionized water was treated with a sand grinder for 2 hours to disperse the average particle size to about 0.8μ and develop color. An agent dispersion liquid (f) was obtained.
The dispersion (f) had a solid content of 45% and a developer concentration of 40%.

[0042] 4 Production Example of color developer of Developer Dispersion (g) ~ (i) ( 4- isopropoxyphenyl) sulfonyl phenols, 2,2'-6,6'-tetrabromo-4,4'- The color developer dispersions (g) to (i) were sequentially produced in the same manner as in the production example of (f) except that sulfonyldiphenol or 4-4-sulfonyldiphenol was used. The dispersions (g) to (i) have a solid content of 45%,
The developer concentration was 40%.

Example of Production of Recording Sensitivity Improver Dispersion (j) Sandwich a mixture of 55 parts of aluminum hydroxide, 12.5 parts of 40 wt% acrylic emulsion (same as above) and 32.5 parts of deionized water. Using a grinder 2
Dispersion (j) was obtained by dispersing the average particle size to about 0.8 μm by time treatment. The dispersion (j) had a solid content of 60% and a recording sensitivity improving agent concentration of 55%.

Production Example of Recording Sensitivity Improver Dispersion (k) A mixture of 55 parts of mica, 20 parts of 25% polyvinyl alcohol and 25 parts of deionized water was treated with a sand grinder for 2 hours to give an average particle size of about Dispersion into 0.8 μm gave a dispersion (k). The dispersion (k) has a solid content of 60%,
The recording sensitivity improver concentration was 55%.

Example 1 19 parts of an aqueous dry emulsion and a color developer dispersion (a)
20 parts, 50 parts of the developer dispersion (f) and 33 parts of the recording sensitivity improver dispersion (j) were mixed to obtain a laser marking composition of Example 1 having a solid content of 46.1%. The composition obtained was applied to a gravure coater (200 mesh, plate depth 20).
μ) on aluminum vapor-deposited paper at 50 m / min. This was dried at 80 ° C. for 3 seconds to form a 2 μm-thick crosslinked coating layer for laser marking. Then, the vapor-deposited paper was irradiated with a laser beam at an energy of 0.6 J / cm ² by a carbon dioxide gas laser (Unimark, manufactured by Ushio Inc.) using a stencil capable of producing numbers to form marks.

Examples 2 to 16 : Aqueous normally dry emulsions and color developer dispersions shown in Table 1
The developer dispersion and the recording sensitivity improver dispersion were blended to produce the laser marking compositions of Examples 2-16.
Then, marks were formed on the base materials shown in Table 1 in the same manner as in Example 1.

[0047] were prepared composition to Comparative Examples 1 to 3 formulations those described in Comparative Examples 1-3 in Table 1. Then, a mark was formed in the same manner as in Example 1.

Table 1 shows the compounding amounts and kinds of base materials in Examples and Comparative Examples.

[0049]

[Table 1]

In Table 1, is a water-soluble resin solution of 15% polyvinyl alcohol, and is a 40% by weight acrylic emulsion (same as above).

Next, the marks obtained in Examples and Comparative Examples were tested. The performances of Examples and Comparative Examples are shown in Table 2.

[0052]

[Table 2]

In Table 2, performance was evaluated according to the following criteria.

Laser printing suitability : evaluated by visual inspection according to the following criteria. O indicates that the laser printing is extremely good. In the case of Δ, the laser marking is recognized but not clear. Marking with a laser is not recognized for x.

Coloring property : Visual evaluation was made according to the following criteria. ○ indicates a clear color. Δ is colored but not clear. × is not colored.

Topcoat suitability : A solvent-type topcoat clear in which cellulose is dissolved in an organic solvent of ethyl acetate is barco-coated to a dry film thickness of 1 to 3 μm on the surface of the coating films obtained in Examples and Comparative Examples, and the temperature is set to 80 ° C. It was left for 1 minute to dry. The decoloring resistance of the laser-colored portion and the discoloration resistance (background fog resistance) of the uncolored portion were evaluated by the same method as the above (water resistance).

Water resistance : After being immersed in water at 30 ° C. for 20 days, the decoloring resistance of the laser color-developed portion and the discoloration resistance (background fog resistance) of the uncolored portion were visually evaluated according to the following criteria. In the case of ○, there is no change in both the color of the laser-colored portion and the color of the uncolored portion. In the case of Δ, the color of the laser-colored portion becomes light and it is difficult to identify the mark, and the color of the uncolored portion is discolored and it is difficult to identify the mark. In the case of x, the color of the laser-colored portion is extremely thin and it is difficult to identify the mark, and the color of the uncolored portion is discolored, and it is difficult to identify the mark.

Oil resistance : After rubbing the surface of the laser marking coating twice with gauze impregnated with coconut oil, the decoloring resistance of the laser-colored portion and the discoloration resistance (non-fog resistance) of the uncolored portion are as described above ( Water resistance) was evaluated by the same method.

[0059]

The composition for laser marking of the present invention comprises:
It can be colored by a laser beam to give a good mark to an article, and the laser marking coating is excellent in water resistance, chemical resistance, solvent resistance and the like.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Akiki Niimoto 7-6-2-906 Suzuya, Yono City, Saitama Prefecture (72) Shoichi Hayashibara 1090 Kamiochiai, Yono City, Saitama Prefecture

Claims (4)

[Claims] 1. An aqueous normally dry emulsion prepared by blending (I) a carbonyl group-containing emulsion with a polyhydrazide crosslinking agent, (II) a color former, and (III) a developer. A composition for laser marking. 2. The carbonyl group-containing emulsion contains 2 to 30% by weight of diacetone acrylamide and / or diacetone methacrylamide and at least one monomer selected from acrylic acid, methacrylic acid, acrylamide and methacrylamide in total of 0. ~ 1.5% by weight,
0 to 30% by weight of styrene, 0 to hydroxyl group-containing monomer
10% by weight, and the SP value of the monomer mixture is 8.0
The monomer mixture other than the above which is 9.3 is 38.5-9.
By emulsion-polymerizing the polymerizable monomer mixture (1) containing 8% by weight in the presence of 0.1 to 6.0% by weight of the nonionic and / or anionic surfactant with respect to the polymerizable monomer mixture (1). The composition for laser marking according to claim 1, which is obtained. 3. The composition for laser marking according to claim 1, wherein the polyhydrazide crosslinking agent is an adipic acid dihydrazide compound. 4. A laser marking article having a laser marking crosslinked coating layer and a clear coating layer for topcoat formed on the surface of the composition for laser marking according to claim 1.