JP2013022849A - Laminate for laser marking and laser marking method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate for laser marking which is capable of obtaining a recorded image having excellent light resistance, rub resistance, water resistance, and oil resistance and further having excellent visibility even when energy of a laser beam required for marking is reduced more than before, and a marking method using the same.SOLUTION: The laminate for laser marking includes a heat generating melt composition layer including a material absorbing a laser beam causing neither coloring nor discoloring substantially to generate heat and a material receiving heat generating energy of the absorbing heat generating material to melt on a preliminarily colored substrate having permeation absorption properties, and further includes a protective layer provided thereon. The laser marking method executes recording by laser irradiation, absorption, heat generation, melting, and permeation which take place in this order on the laminate.

Description

  The present invention relates to a laminate for laser marking that performs recording with laser light and a laser marking method using the same. More specifically, the present invention relates to a laser marking laminate capable of marking with low energy, and a laser marking method for recording by irradiating the laminate with laser light.

  For the purpose of product management and quality assurance, it is common to record information such as a production number and a shelf life on a product packaging or a film used for packaging. Conventional recording methods include the thermal transfer method, hot stamp method, and ink jet method. However, since the recording is performed directly on the surface of the film used for packaging or wrapping, the recorded material may be rubbed off or washed with water, oil, etc. The recording was blurred or disappeared and was not fully satisfactory in terms of scratch resistance, water resistance and oil resistance.

  In order to solve these problems, a method has been proposed in which a color-developing layer that is colored by a laser beam protected by a protective layer such as a film is provided and information is recorded by irradiating the laser beam.

  For example, a method has been proposed in which a color-developing layer that develops color by absorption of a laser beam composed of a color developer such as a leuco dye and a developer is provided on one side of a transparent film, and laser light is irradiated from the film side to record. (For example, see Patent Document 1)

  However, since the color was developed with a leuco dye or the like, the light resistance was inferior and was not satisfactory.

  In addition, a packaging body that has a color-developing layer containing a color former that develops color by laser light and can be recorded by laser light irradiation has been proposed (see, for example, Patent Document 2). However, since the color former and the binder resin are simultaneously present in the color development layer, the packaging body is scattered with the color development agent in the color development layer, and the ratio is small and the color density cannot be sufficiently obtained. It was.

The masking layer and the base layer that appears when the masking layer is removed have a contrast that allows the masking layer and the base layer to be easily visually recognized, and the masking layer generates heat and is destroyed by irradiation with laser light. Thus, a laminate for laser printing has been proposed (see, for example, Patent Documents 3 to 4). However, since the concealing layer is removed by irradiating the laser beam, the recorded portion has poor scratch resistance, water resistance, oil resistance, and the like. Furthermore, in order to remove the concealing layer, it is necessary to increase the irradiation energy of the laser beam.
Japanese Patent Laid-Open No. 08-25809 JP 2007-313876 A JP 2008-100385 A JP 09-123606 A

  The present invention is excellent in light resistance, scratch resistance, water resistance, oil resistance, etc., and can obtain a recorded image with high visibility even when the energy of laser light necessary for marking is lower than before. A laminate and a marking method using the same are provided.

In the present invention, an exothermic melting composition layer containing a material that absorbs laser light and generates heat and a material that receives and melts the exothermic energy of the material is disposed on a pre-colored substrate having penetrability. As a result, the above problems have been solved and the present invention has been completed.
That is, the present invention
“1. Exothermic melting that includes a material that absorbs and generates heat by absorbing laser light that does not substantially develop or change color (hereinafter referred to as an absorption heating material) and a material that receives and melts the heat generation energy of the absorption heating material (hereinafter referred to as a melting material). A laminate for laser marking, characterized in that a composition layer is disposed on a pre-colored substrate having penetrability and a protective layer is provided thereon.
2. The laminate for laser marking according to item 1, wherein the melting material has a melting point of 60 ° C to 200 ° C.
3. The laminate for laser marking according to item 1 or 2, wherein the melting material is one or more selected from waxes and organic compounds.
4). The step of irradiating the laser marking laminate according to any one of Items 1 to 3 with laser light, the absorption heat generating material absorbs laser light and generates heat, and the melting material receives the generated energy, A laser marking method comprising: sequentially recording the melted material by melting and penetrating into the substrate by the received heat.
".

  According to the present invention, the melting material melts into the base material, for example, by disposing an exothermic melting composition layer containing the absorption heat generating material and the melting material on a pre-colored base material having penetrability. In order to be recorded and visible by penetrating, marking is possible with lower energy compared to conventional laser marking laminates and marking methods, and even when marking with low energy, visibility is also possible This provides an excellent effect that a high recorded image can be obtained.

Sectional drawing which shows an example of the laminated body for laser markings of this invention

  The laminate for laser marking according to the present invention has an absorption heat generating material, a melting material, a pre-colored base material, and a protective layer as minimum constituent requirements.

  The laminate for laser marking according to the present invention is configured according to the above requirements. The mechanism by which a recorded image marked by irradiating laser light becomes visible is considered as follows. That is, the laser marking laminate of the present invention has an exothermic melting composition layer containing an absorbing heat generating material and a melting material disposed on a pre-colored substrate. Exists in a state where it becomes opaque by scattering light and conceals the substrate. The exothermic melting composition layer can be made opaque by scattering light, for example, by allowing the melting material to exist in a coarse state. When the laminate for laser marking according to the present invention, in which the exothermic melting composition layer is scattered and opaque, is irradiated with laser light, the absorption heating material irradiated with the laser light in the composition emits laser light. Absorbs and generates heat. The exothermic energy is received and melted by the melting material, and permeates and is absorbed by the pre-colored substrate. As a result, it becomes visible as information due to the contrast between the non-irradiated portion of the laser beam and the portion where the molten material is permeated and absorbed by the laser beam irradiation.

  The absorption heating material used in the present invention is a material that can absorb laser light, convert the absorbed light energy into heat energy, and then apply the heat energy to the melting material to melt the melting material. Specific examples include organic pigments, inorganic pigments, dyes, and inorganic materials.

  Organic pigments include fast yellow G, fast yellow 10G, fast yellow FGL, pyrazolone orange, dianisidine orange, benzimidazolone orange HL, lake red 4R, naphthol carmine FB, brilliant fast scarlet, methyl violet lake, rhodamine B lake, Dioxazine violet, Victoria Blue Lake, Peacock Blue Lake, Phthalocyanine Blue R, Brilliant Green Lake, Malachite Green Lake, Phthalocyanine Green 6Y and the like.

  As inorganic pigments, white pigments such as carbon black, titanium oxide, basic lead sulfate, zinc oxide, zinc sulfide, antimony oxide, precipitated barium sulfate, barium carbonate, precipitated calcium carbonate, diatomaceous earth, talc, clay, basic Examples include extender pigments such as magnesium carbonate and alumina white.

  Examples of inorganic materials include simple metals, metal salts, metal hydroxides, metal oxides, and the like. Specifically, examples of the simple metal include iron, zinc, tin, nickel, copper, silver, and gold. Metal salts include copper carbonate, nickel carbonate, manganese carbonate, cobalt carbonate, lanthanum carbonate, magnesium nitrate, manganese nitrate, iron nitrate, cadmium nitrate, zinc nitrate, cobalt nitrate, lead nitrate, nickel nitrate, copper nitrate, Palladium nitrate, lanthanum nitrate, magnesium acetate, manganese acetate, cadmium acetate, zinc acetate, cobalt acetate, lead acetate, nickel acetate, copper acetate, palladium acetate, copper chloride, iron chloride, cobalt chloride, nickel chloride, silver chloride, zinc chloride , Copper phosphate, iron phosphate, cobalt phosphate, copper pyrophosphate, copper sulfate, iron sulfate, cobalt sulfate, copper oxalate, iron oxalate, cobalt oxalate, copper benzoate, iron benzoate, cobalt benzoate, Examples thereof include copper phosphonate having an aromatic ring and silicate mineral.

  Examples of the metal hydroxide include copper hydroxide, aluminum hydroxide, magnesium hydroxide, zinc hydroxide, antimony hydroxide, cobalt hydroxide, nickel hydroxide, iron hydroxide, and lanthanum hydroxide. Examples of the metal oxide include silicon oxide, aluminum oxide, iron oxide, magnesium oxide, cobalt oxide, lead oxide, tin oxide, indium oxide, manganese oxide, molybdenum oxide, nickel oxide, copper oxide, palladium oxide, lanthanum oxide, Examples thereof include antimony tin oxide, indium tin oxide, synthetic zeolite, natural zeolite, and copper-molybten composite oxide.

In the absorption heat generating material used in the present invention, it is preferable that a high contrast is obtained between the pre-colored base material and the exothermic melting composition layer, and when the melting material penetrates the base material and is absorbed, the colored base Those that do not inhibit the color development of the material are preferred. In view of the above, the absorption heat generating material preferably used includes titanium oxide, surface-coated mica, and the like. Although carbon black is colored, it has excellent ability to absorb laser light and generate heat. Since an effect is acquired, it is especially preferable.

  The blending ratio of the absorption heat generating material used in the present invention is 0.1 to 20% by mass with respect to the total mass of the exothermic melting composition. The information tends to be difficult to see, and if it is larger than this range, the heat energy generated by the absorption heating material increases, the melting range of the melting material increases, and the recorded information tends to become unclear. . More preferably, it is 0.5 to 10% by mass, and when it is in this range, the recorded image becomes clear and the visibility becomes high.

  The melting material used in the present invention is a material that can receive and melt the heat generation energy of the absorbing heat generating material, conceal a previously colored base material, and can penetrate into the base material when melted. . Specific examples include waxes and organic compounds. Examples of the waxes that can be used in the present invention include natural waxes and synthetic waxes. For example, paraffin wax, microcrystalline wax, polyethylene wax, and the like are used. Examples of the organic compound include long chain fatty acids and esters thereof, amides, and the like. For example, trilaurin, myristic acid, behenic acid, stearic acid amide and the like are used.

  As described above, the melting material used in the present invention receives heat energy and melts, but the melting point of the melting material is preferably 60 ° C to 200 ° C. If the temperature is lower than this range, the heat resistance of the laser marking laminate tends to be deteriorated. If the temperature is higher than this range, a large amount of energy is required for the melting material to melt, and the amount of melting of the melting material decreases. The recorded information tends to be difficult to view. More preferably, it is 80 ° C. to 160 ° C., and if it is within this range, the heat resistance is sufficient, and the recorded image is clear and the visibility is high, which is preferable.

  The thickness of the exothermic melting composition layer of the laser marking laminate used in the present invention is preferably about 1 μm to 50 μm. If it is smaller than this range, it will be difficult to conceal the pre-colored base material, and the visibility of the recorded image will tend to be inferior. If it is larger than this range, the melting material will melt and penetrate and absorb into the base material. There is a tendency to require more energy. More preferably, it is about 5 μm to 35 μm, and most preferably about 15 μm to 30 μm. Within these ranges, it is preferable because information can be recorded with appropriate energy and the visibility of the recorded image can be sufficiently obtained.

  As an example of a method for disposing the exothermic melting composition layer on a pre-colored base material, the melting material is dispersed in an organic solvent by a ball mill or the like, whereby an organic solvent dispersion of the melting material in a coarse state is obtained. can get. An organic solvent dispersion of the exothermic absorbent composition is obtained by mixing and stirring an absorption exothermic material in the dispersion. An organic solvent dispersion of the exothermic absorbent composition is applied onto a substrate and dried to obtain an exothermic melting composition layer that conceals the substrate.

  Various additives can be added to the exothermic melting composition layer as needed to the extent that the marking is not affected. Specifically, an ultraviolet absorber, various coloring agents, a dispersing agent, etc. are mentioned.

  The pre-colored base material used in the present invention can absorb and absorb when the melting material is melted, and there is a contrast between the laser light non-irradiated portion and the portion where the molten material is permeated and absorbed by laser light irradiation. As long as it can be visually confirmed that the marking has been made, there is no particular limitation, and colored paper, colored cloth, nonwoven fabric, and the like can be used. In addition, since it is visually recognized by the contrast between the laser light non-irradiated portion and the portion where the melting material is permeated and absorbed by the laser light irradiation, the heat-dissipating composition layer that itself scatters light and conceals the substrate. Since the contrast becomes higher, it is preferable to use a pre-colored substrate having low brightness.

  As shown in FIG. 1, the laser marking laminate (1) of the present invention comprises an exothermic melting composition layer containing an absorbing heat generating material (3 a) and a melting material (3 b) on a pre-colored base material (2). An example is a configuration in which (3) and the protective layer (4) are sequentially laminated. When the laminated body is irradiated with laser light, the absorption heat generating material absorbs the laser light and converts the absorbed light energy into heat. The melting material receives and melts the heat energy converted by the absorption heat generating material, penetrates into the base material and is absorbed, and a marking image or the like is formed and recorded.

  The laminate for laser marking of the present invention is provided with a protective layer from the viewpoint of imparting scratch resistance, water resistance, oil resistance and the like. At that time, since the recorded image is clear and visibility is high, the protective layer is preferably transparent and does not absorb laser light.

  The protective layer used in the present invention can be formed by various commonly known coating methods. Specifically, water or an organic solvent is used as a solvent or dispersion medium, and a solution prepared by using various mixing or dispersing machines with a color developing material in the solvent or dispersion medium is disposed on a pre-colored substrate. It can be obtained by removing the solvent or the dispersion medium after coating by the coating technique such as bar coating in contact with the exothermic melting composition layer.

  In addition, after polymerization, monomers or oligomers that can serve as a protective layer are dissolved or dispersed directly or in a solvent, etc., and then applied to the substrate by a coating method such as bar coating, and then irradiated with electron beams, ultraviolet rays, etc. The desired protective layer can also be obtained by polymerization by applying heat. When providing a protective layer, a generally known anchor layer or precoat layer may be provided in order to increase adhesion to the exothermic melting composition layer.

  In addition, a resin film, a sheet, or the like may be used as it is as the protective layer. At this time, it may be provided via an adhesive layer, an adhesive layer, or the like, or may be provided directly on the exothermic melting composition layer.

  The protective layer used in the present invention may further have antifouling properties, heat resistance, light resistance, deterioration resistance, gas barrier properties, antistatic properties, blocking resistance, and the like. Moreover, it is good also as a surface with the slipperiness | lubricity of a surface, and printability.

  In the present invention, examples of lasers that can be irradiated include solid lasers, liquid lasers, gas lasers, semiconductor lasers, fiber lasers, and free electron lasers.

  Examples of the solid laser include a ruby laser, a YAG laser, and a diode-excited solid laser, and examples of the liquid laser include a dye laser. Further, examples of the gas laser include a carbon dioxide laser, a helium neon laser, an argon ion laser, and an excimer laser. Examples of the semiconductor laser include a green laser, and examples of the fiber laser include a FAYb laser.

  The wavelength range of the laser that can be used is 500 nm to 12000 nm, and the intensity thereof is appropriately selected and used with an output that does not damage the laminate for laser marking of the present invention. The wavelength range of the laser that is preferably used is 500 nm to 1200 nm, and the wavelength range of the laser that is particularly preferably used is 500 nm to 700 nm. The laser light used is preferably a YAG laser, a green laser or the like. In particular, when using a green laser, the wavelength of the laser light is short, so the diameter of the laser light irradiation can be reduced, the recording becomes clear, and the irradiation energy per unit output is large, so the output is low. It is particularly preferable because it can be recorded in the same state.

  As a method of marking on the laser marking laminate of the present invention, the following steps are performed. That is, the laser marking laminate is irradiated with laser light emitted from the irradiable laser, and the absorption heating material absorbs the laser light and generates heat. Subsequently, the melting material receives the generated energy, and the melting material is melted by the received heat, and penetrates the pre-colored base material to be absorbed, thereby recording target information and the like.

Examples of the present invention will be described below, but the present invention is not limited thereto.
Example 1
(Preparation of exothermic melting composition coating solution)
Polyethylene wax (melting point 100 ° C. Melting material) 50 parts by weight Ethylcellulose 5 parts by weight Carbon black (absorption heat generating material) 0.5 part by weight Methyl ethyl ketone 50 parts by weight The above ingredients are stirred and mixed in a ball mill for 1 hour, and an exothermic melting composition is applied. A working solution was obtained.
(Preparation of exothermic melting composition layer)
By applying the exothermic melting composition coating solution on a colored paper that has been colored red in advance as a base material and drying at room temperature, the pre-colored base material becomes a light gray color with the exothermic melting composition. A concealed laminate having an exothermic melting composition layer provided on a substrate was obtained. At this time, the thickness of the exothermic melting composition layer was 25 μm.
(Production of laser marking laminate)
An acrylic pressure-sensitive adhesive solution (Esdyne 7850 45% by mass toluene / ethyl acetate solution manufactured by Sekisui Chemical Co., Ltd.) is coated on a transparent 50 μm polyethylene terephthalate film and dried at room temperature to obtain a transparent film. Was provided with an adhesive layer. This film was laminated on the exothermic melting composition layer using a laminator, a protective layer was provided, and a laser marking laminate was obtained.
Laser light is applied to this laminate by a green laser light irradiation device (LP-G050 manufactured by SUNX, laser wavelength: 655 nm, power: 1.0 W, scan speed: 500 mm / s, print pulse cycle: 50 μs, focal length: 225 mm). Irradiated from the protective layer side, the absorbed laser beam is absorbed by the heat generating material to generate heat, and the generated heat is received by the polyethylene wax that is the melting material, and the polyethylene wax melts by the received heat and penetrates into the substrate and absorbs it. As a result, laser marking was performed. When the recorded state of the marked part is visually confirmed, a clear and highly visible recorded image is obtained in which the part irradiated with the laser light turns red and the part not irradiated remains light gray. Was confirmed.

(Example 2)
Using the laser marking laminate of Example 1, laser irradiation was performed under the following conditions. Laser light is irradiated from the protective layer side by a YAG laser light irradiation device (LP-V10U manufactured by SUNX, laser wavelength: 1060 nm, power: 2.4 W, scan speed: 300 mm / s, printing pulse cycle: 20 μs, focal length: 190 mm) Then, laser marking was performed. When the recorded state of the marked part is visually confirmed, a clear and highly visible recorded image is obtained in which the part irradiated with the laser light turns red and the part not irradiated remains light gray. Was confirmed.

(Example 3)
A laser marking laminate was obtained in the same manner as in Example 1 except that the polyethylene wax was fatty acid amide (melting point: 145 ° C.). Further, laser irradiation was performed in the same manner as in Example 2. When the recorded state of the marked part is visually confirmed, a clear and highly visible recorded image is obtained in which the part irradiated with the laser light turns red and the part not irradiated remains light gray. Was confirmed.

Example 4
Surface-coated mica (LAZERFLAIR820 Merck) 2.0 parts by weight Absorbing exothermic agent was used in the same manner as in Example 1 except that 0.05 part by weight of sorbitan monostearate was obtained as a dispersant. It was. Further, laser irradiation was performed in the same manner as in Example 2.
When the recorded state of the marking is confirmed by visual observation, it is confirmed that a clear and highly visible recorded image is obtained in which the portion irradiated with the laser light turns red and the portion not irradiated remains white. It could be confirmed.

(Example 5)
A laser marking laminate was obtained in the same manner as in Example 1 except that polyethylene wax was erucic acid amide (melting point: 80 ° C.). Further, laser irradiation was performed in the same manner as in Example 1.
When the recorded state of the marked part is visually confirmed, a clear and highly visible recorded image is obtained in which the part irradiated with the laser light turns red and the part not irradiated remains light gray. Was confirmed.

(Comparative Example 1)
A laminate for laser marking was obtained in the same manner as in Example 1 except that carbon black was not used. Further, this laminate was irradiated with laser in the same manner as in Example 1, but could not be marked.

(Comparative Example 2)
On a 12 μm PET film substrate, 8 parts of titanium dioxide (material that absorbs and generates heat by Ishihara Sangyo Co., Ltd.), 204 parts (by Sekisui Fuller Co., Ltd., acrylate resin, solid content 45 mass) %, The solution dispersed in the material) is applied by bar coating, the solvent is removed by hot air, and the layer is provided with a thickness of 25 μm, and a conventional laser marking laminate having a laser light absorption exothermic coloring layer is obtained. It was. This laminate was irradiated with laser light under the same conditions as in Example 1 to perform laser marking. When the recorded state of the marking is visually confirmed, the material that absorbs and generates heat and the material that develops color are mixed, and the material that absorbs and generates heat and the material that develops color are scattered. It was confirmed that a recorded material having a low color density and a low contrast was obtained without being used.

記録の視認性：レーザー光を照射した部分の記録画像の視認性を目視により評価した。
◎：記録画像のコントラストが高く、十分な視認性がある。
△：記録画像のコントラストが低く、視認しにくい。
×：記録画像のコントラストがとれず、視認できない。
記録の鮮明性：レーザー光を照射した部分の記録画像の鮮明性を目視により評価した。
◎：記録画像の解像度が高く、非常に鮮明。
○：記録画像の解像度がやや高く、鮮明。
△：記録画像の解像度がやや低く、やや不鮮明。
×：記録画像が得られていない。 Table 1 shows the results of visual evaluation of the recorded state when the laser beams of Examples 1 to 5 and Comparative Examples 1 and 2 were irradiated and marked.

Visibility of recording: Visibility of a recorded image of a portion irradiated with laser light was visually evaluated.
A: The contrast of the recorded image is high and there is sufficient visibility.
(Triangle | delta): The contrast of a recorded image is low and it is hard to visually recognize.
X: The contrast of the recorded image cannot be taken and cannot be visually recognized.
Sharpness of recording: The sharpness of the recorded image of the portion irradiated with the laser beam was visually evaluated.
A: The resolution of the recorded image is high and very clear.
○: The resolution of the recorded image is slightly high and clear.
Δ: The resolution of the recorded image is slightly low and slightly unclear.
X: A recorded image is not obtained.

  As is clear from the results in Table 1, the recorded images obtained by irradiating the laser beams with the laser marking laminates of Examples 1 to 5 were clear and highly visible. On the other hand, the laminates for laser marking of Comparative Examples 1 and 2 were not able to obtain a recorded image or were unclear even when obtained, and were difficult to visually recognize.

  INDUSTRIAL APPLICABILITY The present invention can be used as various marking materials for recording information such as production numbers and expiration dates on product packaging and film used for packaging for the purpose of product management and quality assurance.

DESCRIPTION OF SYMBOLS 1 ... Laser marking laminated body 2 ... Pre-colored base material 3a ... Absorption heat generating material 3b ... Melting material 3 ... Exothermic melting composition layer 4 ... Protective layer

Claims (4)

  An exothermic melting composition comprising a material that absorbs and generates heat by absorbing laser light that does not substantially develop or change color (hereinafter referred to as an absorption heating material) and a material that receives and melts the heat generated by the absorption heating material (hereinafter referred to as a melting material). A laminate for laser marking, wherein a layer is disposed on a pre-colored substrate having penetrability and a protective layer is provided thereon.   2. The laser marking laminate according to claim 1, wherein the melting material has a melting point of 60 ° C. to 200 ° C. 3.   The laminate for laser marking according to claim 1 or 2, wherein the melting material is one or more selected from waxes and organic compounds.   The laser marking laminate according to any one of claims 1 to 3, a step of irradiating a laser beam, a step of absorbing the laser beam and generating heat, and the melting material receiving and receiving the generated energy. A laser marking method comprising: sequentially performing a process of melting a molten material by heat and infiltrating into the substrate.

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