JP2762319B2 - Laser marking method and printing ink - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a high-speed, efficient,
Related to the method of marking on labels, etc., especially after forming the laser coloring material layer in an arbitrary pattern simply by printing method,
It relates to a method for laser marking.

[0002]

2. Description of the Related Art A general method for marking a label or the like is a method of directly obtaining a mark by a printing method.

In this case, the printing method includes pad printing,
Screen printing is a commonly used method.Pad printing has the advantage of being able to print on curved surfaces due to the elastic pad material used in it, but it is not suitable for marking fine patterns and its accurate reproducibility. There is a disadvantage in that. Similarly, in screen printing, marking of a fine pattern and its reproduction are difficult because of its mesh plate.

[0004] In addition, for marking applications requiring real-time performance as much as possible, it is necessary to adjust the time for producing a plate corresponding to the marking pattern or setting printing conditions. Printing is by no means the preferred method.

In recent years, ink jet marking has begun to be used as an alternative method.

Although this method is a marking method that sufficiently satisfies the high-speed and real-time properties that the printing method lacks, it is based on a mechanism for discharging liquid ink from a small-diameter nozzle at a high pressure. The characteristics required of the ink jet printer are quite severe, and sometimes clogging of nozzles which is considered to be caused by ink may occur, thereby increasing the defective rate of marking. This is the problem left to be solved in this scheme.

[0007] Therefore, laser marking has attracted attention as a more efficient marking method at a higher speed, and has already been used in some applications.

[0008] This is mainly done by irradiating a laser beam only to a necessary portion of the substrate surface and heating to change or remove the substrate, or by irradiating a laser to the film coated on the substrate surface to form only the film. removed, a method of marking by attaching a contrast Ru殆Ndodea between laser irradiated and non-irradiated portions of the substrate. From heat
Labels made of paper substrate with color recording area
Marking using non-destructive coloring by laser irradiation
Although there is no practical example yet, various proposals have been made. example
For example, Japanese Patent Application Laid-Open No. 53-52442 discloses that
A label consisting of a thermal recording medium attached to a moving object
Method of printing by applying laser light to the surface to develop heat-sensitive color
Is described. Also, Japanese Patent Application Laid-Open No. 55-11857
The report shows a method similar to the one described above,
The thermochromic region is a thermochromic ink layer. Also,
JP-A-58-145493 discloses a color former and a color former.
Containing specific additives, which should also be referred to as sensitizers
A thermosensitive recording medium is described. For other lasers
Various thermal recording media have been proposed, but as described above,
Such recording media and recording methods are not sufficiently practical.
Not.

[0009]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method capable of performing high-speed, efficient and non-destructive marking even on a paper-based label or the like, and a marking material used therefor. .

[0010]

Means for Solving the Problems The present inventors have optimized in view of such circumstances, the result of intensive studies for non-destructive color development by laser irradiation, the Re coloring agent and its such leuco dyes
A printing ink containing a specific developer, such as a gravure printing ink, is printed on the base material and then irradiated with a laser. And find that it can be easily marked,
The present invention has been completed.

That is, the present invention relates to a laser marking method for irradiating a printed portion of a substrate on which a printing ink containing a color former and a developer has been printed with a laser, by converting a phenolic compound to methylol as a developer. laser marking method which comprises using an object, and rail, characterized by containing a such color former and the developer
The present invention provides a printing ink for marking .

As the color former used in the present invention, any color former used as an electron donor in a thermosensitive recording medium can be used. For example, triphenylmethphthalide,
Colorless leuco dyes such as phenothiazines, spiropyrans, rhodamine lactams, leucomilans and fluorans are preferred, with fluoranes being preferred.

Specific examples of leuco dyes include 3,3-
Bis (p-dimethylaminophenyl) phthalide, 3,3
-Bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (also known as crystal violet lactone = CVL), 3,3-bis (p-dimethylaminophenyl) -6-aminophthalide, 3,3-bis (p- Dimethylaminophenyl) -6-nitrophthalide, 3,3-bis (p-dimethylaminophenyl) phthalide, 3,3-
Bis 3-dimethylamino-7-methylfluoran, 3-
Diethylamino-7-chlorofuran, 3-diethylamino-6-chloro-7-methylfluoran, 3-diethylamino-7-anilinofluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 2- ( 2-fluorophenylamino) -6-diethylaminofluoran, 2- (2-fluorophenylamino) -6-di-n
-Butylaminofluoran, 3-piperidino-6-methyl-7-anilinofluoran, 3- (N-ethyl-p-
Toluidino) -7- (N-methylanilino) fluoran, 3- (N-ethyl-p-toluidino) -6-methyl-7-anilinofluoran, 3-N-ethyl-N-isoamylamino-6-methyl- 7-anilinofluoran,
3-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluoran, 3-N, N-diethylamino-7-o-chloroanilinofluoran, rhodamine B lactam, 3-methylspirodinaphate Pyran, 3-ethylspirodinaphthopyran, 3-benzylspironaphthopyran and the like can be mentioned.

[0014] As the color developer, methylolated products of phenolic compounds among those belonging to the category of acidic substances to be used as the electron acceptor in the heat-sensitive recording material and the like. Of course, in addition to the color developer of the present invention, it is also effective to use an appropriate one of various color developers used for the thermosensitive recording medium.

Examples of the ingredients thereof Examples of these developer include phenol, 4-phenylphenol, 4-hydroxyacetophenone, 2,2'-dihydroxydiphenyl, 2,2 '
-Methylenebis (4-chlorophenol), 2,2'-
Methylenebis (4-methyl-6-t-butylphenol), 4,4'-isopropylidenediphenol (also known as bisphenol A), 4,4'-isopropylidenebis (2-chlorophenol), 4,4'-isopropylidene Bis (2-methylphenol), 4,4'-ethylenebis (2-methylphenol), 4,4'-thiobis (6
-T-butyl-3-methylphenol), 1,1-bis (4-hydroxyphenyl) -cyclohexane, 2,
2'-bis (4-hydroxyphenyl)-n-heptane, 4,4'-cyclohexylidene bis (2-isopropyl phenol), methylolated products of phenolic compounds such as 4,4'-sulfonyl diphenol No.

The color former and the color developer are usually used in a range where the weight ratio of the color developer / the color former is 0.1 / 1 to 5/1, and the weight ratio is preferably 0.5 / 1. A range of 範 囲 3/1 is preferable.

Examples of the printing ink of the present invention include those containing the above color former and developer. The amount of the color former and the developer used is in a range where the total of the color former and the developer is 10 to 90% by weight, preferably 30 to 95% by weight in the nonvolatile components in the printing ink.

The method for incorporating a color former and a color developer into the printing ink is not particularly limited as long as the color former is not colored. For example, it may be added during the production of the ink, or it may be added. May be added later to the ink.

The type of printing ink is not particularly limited, among others gravure printing ink, in particular leuco dyes, water was used methylolated product of phenolic compound as a developer as a color former - alcohol-based gravure printing The ink can easily form a laser coloring layer in an arbitrary pattern, has high sensitivity to laser irradiation, and is capable of marking even if there is an overcoat layer on the coloring layer. This is preferred because it has the advantage that there is no blank color development in the system and it can be used in a one-liquid dispersion system.

The leuco dye used in the water-alcohol gravure printing ink is preferably a fluoran dye. Methylolated of phenolic compounds
The by chromogenic methylolated Monogare Za irradiated portion of the phenol, preferred especially in view of excellent non-coloring of clearness and laser unirradiated portion.

As the phenol methylol compound,
For example, a low molecular weight compound having a molecular weight of 200 or less in which 1 to 3 methylol groups are added to a mononuclear phenol obtained by reacting phenol and formaldehyde in the presence of an alkali catalyst.

[0022]

[0023]

[0024]

[0025] or a leuco dye, both the water and the methylolated product of phenolic compounds - The binder resin used in the alcohol gravure printing ink, is soluble in lower alcohols, and include film formation capable neutral resin, For example, polyamide resin, polybutyral resin, nitrocellulose resin, acrylic resin, vinyl chloride-vinyl acetate copolymer resin, urethane resin, petroleum resin, chloride rubber resin, cyclized rubber resin, alkyd resin Etc.
Of these, polyamide resins are preferred.

The printing ink thus obtained may be printed on a substrate under the condition that the coloring agent is not colored, and the printing conditions are not particularly limited. The substrate used in the present invention may be any substrate as long as it can be printed, and examples thereof include paper, plastic, a metal plate, paper having a metal deposition film, and plastic.

The laser used in the present invention may be a pulsed laser capable of giving an energy of 0.5 joules / cm ² · pulse or more, preferably 1 joule / cm ² · pulse or more, to an irradiation surface, or a laser having an output of 0.5 W. A scanning laser having the above output is preferable, for example, a carbon dioxide laser, a carbon monoxide laser, a semiconductor laser,
Yttrium aluminum glass (YAG) laser, excimer laser, etc.
versionly Excited Atomopha
A ric Pressure (TEA) type carbon dioxide laser or a scanning carbon dioxide laser is particularly preferable in that black marking with good visibility can be obtained.

[0028]

The present invention will be described more specifically below with reference to examples and comparative examples. The parts and percentages in the examples are on a weight basis.

Example 1 150 g of phenol, 300 g of a 37% formalin aqueous solution and 30 g of a 50% aqueous sodium hydroxide solution were charged into a 1-liter four-necked flask equipped with a thermometer, a stirrer, and a reflux condenser. For 5 hours.
Thereafter, excess formalin was removed over a period of about 30 minutes under a weak reduced pressure (250 to 300 mmHg).

100 parts of an aqueous solution of the thus obtained phenol methylol compound having a nonvolatile content of about 50%, fluoran black leuco dye TG-11 [Nippon Kayaku Co., Ltd. 2
-(2-fluorophenylamino) -6-diethylaminofluorane] and 25 parts of nylon resin M995F
20% methanol solution of Nippon Rilsan Co., Ltd. 12
Five parts were diluted with 150 parts of methanol and sufficiently stirred with a sand mill to obtain a gravure printing ink.

Using the obtained gravure printing ink,
It was gravure-printed on an aluminum-deposited film of aluminum-deposited paper using a 5 μm Helio plate and dried. Using a TEA-type carbon dioxide laser, a laser having an irradiation energy of 1.4 joules / cm ² · pulse was irradiated on the dry printed film through a metal mask for one pulse (pulse width: about 3 μsec) to perform marking. Table 1 shows the viscosity, printability and marking results of the gravure printing ink.

The viscosity of the gravure printing ink was determined by Zahn Cup No. The number of measurement seconds according to 3 and the printability were evaluated by visual evaluation of the smoothness of the printing ink coating film (◎: particularly good, ○: good, Δ: slightly poor, ×: poor). And the overall evaluation of sharpness (◎: particularly good, ：: good, Δ: slightly poor, ×: poor).

Example 2 10 parts of a 50% aqueous solution of a methylolated phenol obtained in Example 1 and 10 parts of a fluoran leuco dye TG-21 [2- (2-fluorophenylamino)-manufactured by Nippon Kayaku Co., Ltd.]
6-di-n-butylfluorane] and 40 parts of a 30% methanol solution of polybutyral resin SREC-B (Sekisui Chemical Co., Ltd.) as a binder resin and 40 parts of methanol as a diluent were added to a sand mill. And sufficiently stirred to obtain a gravure printing ink.

The obtained gravure printing ink was used in Example 1.
After printing under the same conditions as above, marking was performed by irradiating a TEA-type carbon dioxide laser. Table 1 shows the viscosity, printability and marking results of the gravure printing ink.

Example 3 125 parts of a fluoran leuco dye TG-11 and methylolated phenol [Methanol 700 manufactured by Hitachi Chemical Co., Ltd.]
2B] of a 50% aqueous solution and nylon resin M99
125 parts of a 20% methanol solution of 5F
After dilution with 50 parts, an ink for gravure printing was obtained in the same manner as in Example 1 and then printed, followed by irradiation with a TEA-type carbon dioxide laser and marking. Table 1 shows the viscosity, printability and marking results of the gravure printing ink.

Example 4 The gravure printing ink obtained in Example 3 was printed on aluminum-evaporated paper and dried, and then nitrocellulose-based gravure OP varnish [SF8 manufactured by Dainippon Ink and Chemicals, Inc.]
15] to cover the coloring material ink layer. Using a TEA-type carbon dioxide laser, a laser having an irradiation energy of 1.4 joules / cm ² · pulse was irradiated through the metal mask for one pulse (pulse width: about 3 μsec) to perform marking. Table 1 shows the viscosity, printability and marking results of the gravure printing ink.

[0037]

[0038]

[0039]

[0040]

[0041]

[0042]

[0043]

Comparative Example 1 Example 4 except that printing of the gravure printing ink was omitted.
When the marking was carried out in the same manner as in the above, slightly white marking was obtained, but there was no contrast and it could not be used practically.

[0045]

[Table 1]

[0046]

According to the laser masking method of the present invention, a laser coloring layer can be easily formed in an arbitrary pattern, and high-speed, efficient and non-destructive marking can be performed. For this reason, the method of the present invention is particularly suitable for marking labels, wrapping paper, nameplates, cards and the like.

Continuation of the front page (51) Int.Cl. ⁶ identification symbol FI B41M 5/36 C09D 11/10 C09D 11/02 B41M 5/18 108 11/10 114 (56) References JP-A-55-63293 (JP, A) JP-A-1-188390 (JP, A) JP-A-2-76779 (JP, A) JP-A-62-243619 (JP, A) JP-A-4-344286 (JP, A) (58) Survey Field (Int.Cl. ⁶ , DB name) B41M 5/30

Claims (8)

(57) [Claims] 1. A laser marking method printing ink containing a color former and the developer to perform laser irradiation on the printed portion of the printed substrate, the use of a methylolated product of phenolic compound as a developer Laser marking method characterized by the above-mentioned. 2. The method according to claim 1 , wherein the methylolated phenolic compound is soluble in water. 3. The method according to claim 1 , wherein the methylolated phenolic compound is a methylolated phenol. 4. A printing ink containing a color former and the developer, laser marking, characterized in that it contains the methylolated product of phenolic compound as a developer
For printing ink. 5. The ink according to claim 4 , wherein the methylolated phenolic compound is soluble in water. 6. The ink according to claim 4 , wherein the methylolated phenolic compound is a methylolated phenol. 7. A gravure printing ink .
6. The ink according to any one of 6 . 8. The ink according to claim 7, wherein the binder resin contains a neutral resin that is soluble in lower alcohol and is capable of forming a film.