JP6008726B2 - Colored sheet and marking processing method - Google Patents

Description

  The present invention relates to a colored sheet and a marking processing method.

Conventionally, in the process of manufacturing component parts and the like, a part number, a manufacturing date, and the like are marked as a character string or a two-dimensional code in order to reliably identify the part.
The marking method is appropriately selected according to the material and shape of the part to be marked. For example, by pressing on a workpiece such as a metal part or various products while vibrating the stylus at high speed, a method that stamps alphanumeric characters or marks, or a dye-containing layer is formed on the surface of a target part made of thermoplastic resin. A method is known in which the dye-containing layer is directly heated with a thermal pen or the like to activate the dye and soften the substrate to fix the dye on the surface of the substrate.

  In addition, as a marking processing method using a laser beam, there is a method of performing damage or processing on a workpiece surface by a laser beam. Marking using a laser beam is good in productivity because high-speed marking is possible, but it is necessary to use a large laser oscillator and an expensive galvano scanner or an XY stage, which makes the apparatus expensive. It was.

Therefore, in order to realize downsizing and simplification of the apparatus, Patent Document 1 discloses that a droplet containing an infrared absorber is applied so as to form a predetermined pattern on the surface of a thermoplastic resin member using an inkjet head. And a method of irradiating the resin surface with a laser beam having a wavelength in the infrared region from the laser head under irradiation conditions such that the applied infrared absorber is fixed on the surface of the resin, thereby melting and fixing the infrared absorber on the resin surface. Has been.
However, this marking method has a major limitation in that the color that can be written is a single color and cannot be multicolored.

In Patent Document 2, as a technique relating to laser color marking that enables multicolor coloring, a colorant-containing layer is formed on the surface of a thermoplastic resin member, and a laser beam is applied to the colorant-containing layer along a predetermined marking shape. Is applied to soften the portion of the thermoplastic resin member irradiated with the laser beam to fix the colorant, and to develop a marking shape on the surface of the thermoplastic resin member.
However, in this method, since the colorant-containing layer is uniformly applied to the front surface of the surface of the thermoplastic resin member and then irradiated with a laser beam in a desired shape, the colorant-containing layer is reformed in order to increase the number of colors. There was a problem that it was necessary and productivity was bad.

Further, in Patent Document 3, in the field of textile printing, after disperse dye is put on a fabric made of thermoplastic synthetic fiber, the irradiated portion is heated by irradiating a CO ₂ laser, and simultaneously with drying, the disperse dye is put inside the fiber. A dyeing method for diffusion dyeing is disclosed.
However, since the wavelength of the CO ₂ laser beam has high spectral transmittance (that is, low absorption) for some thermoplastic synthetic fibers, the output of the laser beam in order to generate heat in these thermoplastic synthetic fibers. There was a problem that energy efficiency was bad.

In Patent Document 4, a full-color ink is applied to the surface portion of a thermoplastic resin member by inkjet, and the wavelength of a quantum cascade laser capable of wavelength selection in the infrared region is selected by the absorbance of the thermoplastic resin member. A laser beam having a different wavelength is used to scan and irradiate the applied portion of the ink applied to the surface of the thermoplastic resin member, and the ink is applied to the surface portion of the thermoplastic resin member by heat generated at the surface portion of the thermoplastic resin member. A marking method for fixing by diffusion or melting and fixing is disclosed.
With this marking processing method, multicolor marking can be performed. Moreover, the laser irradiation apparatus to be used can use a low-power semiconductor laser (quantum cascade laser).

JP 2008-155232 A JP 2008-12869 A JP 59-106589 A JP 2012-11689 A

However, according to the marking processing method described in Patent Document 4, it is necessary to change the wavelength of the laser beam used according to the type of the resin material of the target resin molded product, and the target resin material was changed. In some cases, it is inefficient for industrial use because it is necessary to select and adjust the optimum wavelength according to the target material each time.
In addition, since an ink jet method is employed as a method of applying ink to the surface of the thermoplastic resin member, it is not suitable for application to a curved surface. That is, in order to perform laser marking on a curved surface, an ink jet head capable of three-dimensional operation following the curved surface is required, and there is a problem that the apparatus becomes large and expensive.
Furthermore, when the compatibility between the ink and the resin molded product to be colored is poor, the ink diffuses on the surface of the resin molded product, and there is a problem that clear marking cannot be performed.

In order to solve the above-described problems, the present invention is a colored sheet used when performing a marking process for irradiating a laser beam toward the surface of a thermoplastic resin member and fixing a dye to the irradiation position of the laser beam. And having a structure in which a heating layer that absorbs radiation energy of the laser beam to generate heat upon irradiation with the laser beam and a colored layer containing a dye that is fixed on the surface of the thermoplastic resin member are laminated, and the coloring in a state where the layer side is brought into contact with the surface of the thermoplastic resin member, by irradiation of the laser beam from the heating layer side, the by heat generated in the heating layer is melted dye in the colored layer Rutotomoni the thermoplastic resin The surface of the member is softened so that the dye of the colored layer can be fixed on the surface of the thermoplastic resin member.

The present invention is the colored sheet, wherein the heat generating layer has a black color.
The present invention is the colored sheet, wherein the heat generating layer contains metal particles or metal oxide particles.
The present invention is the colored sheet, wherein the thickness of the colored layer is 30 μm or less.
The present invention is the colored sheet, wherein the dye of the colored layer is a fluorescent paint.

The present invention also toward the surface of the thermoplastic resin member is irradiated with laser beam, and a marking method to fix the dye, the heat generating layer which generates heat by the irradiation of the laser beam relative to the irradiation position of the laser beam, Arranging a colored sheet having a structure in which a colored layer containing a dye to be fixed to the surface of the thermoplastic resin member is laminated, in a state where the colored layer side is in contact with the surface of the thermoplastic resin member; the laser is irradiated from the heating layer side, said surface of the heat generated in the heating layer is melted dye in the colored layer Rutotomoni the thermoplastic resin member is softened, the thermoplastic dye of the colored layer look including a step of fixing the surface of the resin member, wherein the laser beam, the thermoplastic resin member by heat generation of the heat generating layer by irradiation of the laser beam Characterized in that it is an output that can be heated to the softening point.

  According to the present invention, since the laser beam is absorbed in the heat generating layer and converted into thermal energy, the laser beam does not depend on the spectral transmittance (that is, the laser beam absorption rate) of the target thermoplastic resin member material. Therefore, it is not necessary to adjust the wavelength appropriately according to the material of the target thermoplastic resin member, and the apparatus can be simplified.

  Further, if the colored sheet is arranged on the target thermoplastic resin member and has a configuration in which the laser beam is irradiated from above, the colored sheet can be arranged following the target thermoplastic resin member. Marking on curved surfaces is also possible.

  Furthermore, since the colored layer is formed on the colored sheet, the target thermoplastic resin member does not diffuse even if the compatibility with the dye is poor, and clear marking is possible. .

  In addition, when the heat-generating layer has a black color, laser irradiation is performed, so even when the laser beam has a wavelength in the visible light region, the same color dye as the laser beam is melted and fixed to the surface portion of the target thermoplastic resin member. can do.

It is a schematic diagram showing the marking processing method which is one Embodiment of this invention. In the marking processing method which is one embodiment of the present invention, it is a cross-sectional schematic diagram showing the state of the heat transfer area of each colored sheet layer and the thermoplastic resin member when marking on the thermoplastic resin member, FIG. ) Represents the state immediately after laser irradiation, FIGS. 2B and 2C represent a state in which the heat transfer region in the heat generation layer and the colored layer is expanded, and FIG. 2D represents the surface of the thermoplastic resin member. This represents how the dye is colored. It is a schematic diagram which shows the behavior of the heat transfer area | region of a thermoplastic resin member, Fig.3 (a) shows the mode of the molecular lattice of the thermoplastic resin member before a heating, FIG.3 (b) shows the thermoplastic resin under a heating. The state of the molecular lattice of the member is shown. It is a schematic diagram which shows the jig | tool for preparation of a colored sheet, and a preparation method. It is a schematic diagram which shows the basic composition of a laser irradiation apparatus. It is a schematic diagram showing the marking method which is one embodiment of the invention, and shows the case where the target thermoplastic resin member has a curved surface. The marking result obtained in the Example is shown.

Hereinafter, a colored sheet which is an embodiment to which the present invention is applied will be described in detail with reference to the drawings.
In addition, in the drawings used in the following description, in order to make the features easy to understand, there are cases where the portions that become the features are enlarged for the sake of convenience, and the dimensional ratios of the respective components are not always the same as the actual ones. Absent.

<Outline of configuration>
FIG. 1 shows a marking processing method according to an embodiment of the present invention. In the marking processing method of this embodiment, the colored sheet 1 is arranged on the surface 2a of the thermoplastic resin member 2 to be marked, and the laser beam 5 is condensed and irradiated on the surface 1a of the colored sheet 1 by the laser irradiation device 4. Thus, marking is performed by fixing the dye at the position corresponding to the spot region S on the surface 2a of the thermoplastic resin member.

2A to 2D are schematic cross-sectional views showing a state in which marking is performed by irradiating a laser beam 5 onto a thermoplastic resin member 2 on which a colored sheet 1 according to an embodiment of the present invention is arranged.
The colored sheet 1 is roughly configured by having at least two layers of a heat generating layer 6 and a colored layer 7 containing a dye. Moreover, the structure which has the transparent base sheet 8 in the one surface of the heat generating layer 6 and the surface 6a on the opposite side to the colored layer 7 may be sufficient.
In addition, in this specification, the surface 1a of the colored sheet 1 means the surface on the side where the heat generating layer 6 is formed in the layer structure of the heat generating layer 6 and the colored layer 7, and in the case where the base sheet 8 is provided. Suppose that the surface of the base sheet 8 is the surface 1a of the colored sheet 1.

As shown in FIGS. 2A to 2D, the colored sheet 1 is disposed on the surface 2 a of the thermoplastic resin member 2 with the colored layer 7 facing the thermoplastic resin member 2 (with the heat generating layer 6 on the upper side). Has been.
The laser beam 5 is applied to the surface 1 a of the colored sheet 1 arranged on the surface 2 a of the thermoplastic resin member 2, that is, the surface of the base sheet 8. Since the base sheet 8 is transparent, it transmits the laser beam 5. Therefore, it can be considered that the laser beam 5 is applied to the surface 6 a of the heat generating layer 6.

As shown in FIG. 2A, most of the radiant energy of the laser beam 5 is absorbed by the heat generating layer 6 and converted into heat energy. That is, the spot region S irradiated with the laser beam 5 on the surface 6a of the heat generating layer 6 generates heat. At this time, the central portion of the spot region S is heated to about 150 ° C. to 300 ° C.
Heat generated on the surface 6 a of the heat generating layer 6 is transferred to the inside of the heat generating layer 6, and a heat transfer region 6 b is formed inside the heat generating layer 6.

  As shown in FIG. 2B, the heat transfer region 6 b of the heat generating layer 6 expands according to the irradiation time of the laser beam 5 and eventually reaches the boundary surface 7 a between the heat generating layer 6 and the colored layer 7. The heat of the heat generating layer 6 is transferred to the colored layer 7, and the colored layer 7 is heated to form a heat transfer region 7 b inside the colored layer 7. In the heat transfer region 7b, the contained dye is activated when the temperature is 120 ° C. or higher.

As shown in FIGS. 2C and 2D, the heat transfer region 7 b of the colored layer 7 expands according to the irradiation time of the laser beam 5 and eventually reaches the surface 2 a of the thermoplastic resin member 2. The heat of the colored layer 7 is transmitted to the thermoplastic resin member 2, the thermoplastic resin member 2 is heated, and a heat transfer region 2 b is formed inside the thermoplastic resin member 2.
In the heat transfer region 2b inside the thermoplastic resin member 2, the temperature rises due to heat, reaches the softening point of the thermoplastic resin, and the thermoplastic resin member 2 softens. As a result, the molecular lattice of the thermoplastic resin is opened, the activated dye of the colored layer 7 enters the open portion, and then the irradiation of the laser beam 5 is stopped, the thermoplastic resin member 2 is cooled, and the molecular lattice 2c. Closes and the dye is fixed.

The behavior of the heat transfer region 2b of the thermoplastic resin member 2 will be described based on FIGS. 3 (a) and 3 (b). FIG. 3A is a diagram schematically showing the state of the molecular lattice 2c of the thermoplastic resin member 2 before heating. FIG. 3B is a diagram schematically showing the state of the molecular lattice 2c of the thermoplastic resin member 2 being heated.
As shown in FIG. 3A, the molecular lattice 2c has a regularly arranged lattice structure. The molecular lattice 2c of the thermoplastic resin member 2 is formed smaller than the molecular size of the dye contained in the colored layer 7, and the dye does not enter the thermoplastic resin member 2 in about 1 to 2 minutes.

On the other hand, as shown in FIG. 3 (b), the molecular lattice 2c being heated has active molecular activity, and its lattice size is locally larger than the molecular size of the dye contained in the colored layer 7 locally. This allows the dye to enter.
Thereafter, when the irradiation of the laser beam 5 is stopped, the thermoplastic resin member 2 is cooled and the molecular lattice 2c is closed. That is, since the state shown in FIG. 3A is obtained, the dye is fixed.

<Components>
Hereinafter, constituent elements according to embodiments of the present invention will be described in detail with reference to the drawings as necessary.
(Thermoplastic resin member)
The thermoplastic resin member 2 that is an object to be subjected to laser marking according to the present invention is a molded product made of a thermoplastic resin that is softened by heating. If it is a thermoplastic resin, engineering plastics can be used in addition to general-purpose plastics and semi-general-purpose plastics.
For example, polyethylene (hereinafter referred to as PE), polypropylene (hereinafter referred to as PP), and polymethyl methacrylate resin (hereinafter referred to as PMMA) are exemplified. In addition, polymethylpentene, polybutene, crystalline polybutadiene, polystyrene, polybutadiene, and polytetrafluoro Ethylene (hereinafter PFE), styrene butadiene resin, polyvinyl chloride, polyvinyl acetate, polyvinylidene chloride, ethylene vinyl acetate copolymer (EVA, AS, ABS, ionomer, AAS, ACS), polymethyl methacrylate, polyacetal (polyoxy) Methylene), polyamide, polycarbonate, polyphenylene ether, polyethylene terephthalate, polybutylene terephthalate, polyarylate (U polymer), polystyrene, polyethersulfone, polyimide, polyester Amide-imide, polyphenylene sulfide, polyoxybenzoyl, polyether ether ketone, polyetherimide, liquid crystal polyester, cellulose acetate, cellulose butyrate, cellophane, can be used celluloid, a thermoplastic elastomer.
In addition, these resins may be colorless and transparent or any color.

(Colored sheet)
As shown in FIGS. 2A to 2D, the colored sheet 1 has at least a heat generating layer 6 and a colored layer 7. Further, in the case of adopting a manufacturing method in which the heat generating layer 6 and the colored layer 7 are sequentially formed on the transparent base sheet 8 as the manufacturing method of the colored sheet 1, the base sheet 8 may be provided.

(Colored layer)
The configuration of the colored layer 7 will be described in detail with reference to FIGS.
The thickness of the colored layer 7 is preferably 5 μm or more and 30 μm or less.
It is not only difficult in the manufacturing process to reduce the thickness of the colored layer 7 to 5 μm or less, but the amount of the dye in the colored layer 7 is insufficient, and the thermoplastic resin member 2 may not be clearly colored. .
Further, when the thickness of the colored layer 7 is 30 μm or more, the heat energy generated in the heat generating layer 6 and transmitted to the colored layer 7 reaches the thermoplastic resin member 2 in the heat transfer process transmitted to the thermoplastic resin member 2. The heat energy is diffused into the thermoplastic resin member 2 and the heat transfer efficiency to the thermoplastic resin member 2 is deteriorated. That is, it is necessary to lengthen the irradiation time of the laser beam 5 and the energy efficiency is deteriorated. Furthermore, since the irradiation time of the laser beam 5 becomes longer, the heat transfer region 6b of the heat generating layer 6 and the heat transfer region 7b of the colored layer 7 are formed larger. Therefore, heat transfer to the boundary surface 7a with the colored layer 7 is also performed in a wide range, and furthermore, heat transfer to the surface 2a of the thermoplastic resin member 2 is also performed in a wide range. Thereby, the marking range is widened with respect to the spot diameter of the laser beam 5, and the marking becomes unclear.
However, for example, when the laser output is 150 mW or more, the irradiation time of the laser beam 5 can be shortened, so that clear marking is possible even if the thickness of the colored layer 7 is 30 μm or more. Become.

In the colored layer 7, the dye is bound by a binder. As an example of the binder, a polyvinyl alcohol resin (hereinafter referred to as PVA) or a mixture of PVA and glycerin can be used.
Other binders include vinyl chloride copolymers, polyurethane resins, acrylic resins, polyester resins, acrylonitrile-butadiene copolymers, polyamide resins, polyvinyl butyral resins, nitrocellulose, styrene butadiene copolymers. Coalescence, acetal resin, epoxy resin, phenoxy resin, polyether resin, polyimide resin, phenolic resin, polybutadiene elastomer, synthetic rubber resin, and other thermoplastic resins, polycondensation phenol resin, epoxy resin, polyurethane curable resin, Thermosetting of urea resin, butyral resin, polymeric resin, melanin resin, alkyd resin, silicone resin, acrylic reaction resin, polyamide resin, epoxy-polyamide resin, saturated polyester resin, urea formaldehyde resin, etc. Resin, a radiation curable resin or mixtures thereof may be used.
Among these, it is preferable to use one having high thermal conductivity.

  The color of the dye contained in the colored layer 7 may be any color. As the dye, for example, each color of Polylon (trade name) of Tanaka Nao Dye Store, Inc., BLACK, BLUE of KIWALON POLYESTER MAX-SL (trade name) of Kiwa Chemical Co., Ltd. can be used.

Further, a fluorescent dye may be used as the dye. By using the fluorescent dye as the dye of the colored layer 7, the marking applied to the target thermoplastic resin member is not visible under visible light, but the fluorescent dye emits fluorescence when irradiated with ultraviolet light. Visual recognition is possible.
Therefore, it can be used as a marking that can be recognized only by a person in charge of manufacturing by irradiating an ultraviolet light. For example, a serial number or a two-dimensional code can be marked without impairing the design of the product. .
It can also be used for the purpose of preventing forgery.
In addition, since the fluorescent dye itself emits light when irradiated with ultraviolet light, sufficient contrast can be obtained even if the dye is melted and fixed to the thermoplastic resin member 2 in a very small amount. It is expensive and useful in this respect.

  The dye is preferably contained in a mass ratio with the binder of about 1: 1 to 2: 1. When the mass ratio of the dye exceeds twice the mass of the binder, the smoothness of the contact surface with the thermoplastic resin member 2 in the colored layer 7 is lost, and the adhesion with the thermoplastic resin member 2 is deteriorated. Thereby, the heat transfer efficiency from the colored layer 7 to the thermoplastic resin member 2 is lowered, and the processability of the marking process may be deteriorated. If the mass ratio of the dye is lower than the mass of the binder, marking with sufficient contrast cannot be performed due to the lack of the dye. Therefore, the above-mentioned range is preferable for the mass ratio of the dye to the binder.

(Heat generation layer)
The configuration of the heat generating layer 6 will be described in detail with reference to FIGS.
The heat generating layer 6 has a configuration in which a pigment component capable of absorbing the radiation energy of the laser beam 5 from the laser irradiation device 4 is bonded with a binder such as PVA. Therefore, it becomes possible to absorb the laser beam 5 irradiated by the laser irradiation device 4 and convert the radiant energy of the laser beam 5 into heat energy with high efficiency.
For example, when a semiconductor laser device that irradiates a laser having a red wavelength region (red laser) is used as the laser irradiation device 4, the heat generation layer 6 is blue or green, so that the light energy of the red laser is efficiently heated. Can be converted into energy.

The film thickness of the heat generating layer 6 is preferably 4 μm or more and 30 μm or less.
It is difficult in the manufacturing process to reduce the thickness of the heat generating layer 6 to 4 μm or less, and the film thickness may be uneven, that is, the thermoplastic resin member 2 may be unevenly colored. .
When the thickness of the heat generating layer 6 is increased, in the heat transfer process of the heat energy generated in the heat generating layer 6, the heat energy is diffused to reach the colored layer 7 and the heat transfer efficiency to the colored layer 7 is deteriorated. That is, it is necessary to lengthen the irradiation time of the laser beam 5 and the energy efficiency is deteriorated.
Moreover, the heat transfer area | region 6b of the heat generating layer 6 will be largely formed because the irradiation time of the laser beam 5 becomes long. Therefore, heat transfer to the boundary surface 7a with the colored layer 7 is also performed in a wide range, and furthermore, heat transfer to the surface 2a of the thermoplastic resin member 2 is also performed in a wide range. Thereby, the marking range is widened with respect to the spot diameter of the laser beam 5, and the marking becomes unclear.
However, for example, when the laser output is 150 mW or more, the irradiation time of the laser beam 5 can be shortened, so that clear marking is possible even if the thickness of the heat generating layer 6 is 30 μm or more. Become.

Further, depending on the type and content of the dye component of the heat generating layer 6, when the film thickness is 30 μm or less, the color density of the heat generating layer 6 becomes insufficient and the radiation energy of the laser beam 5 can be sufficiently absorbed. There are cases where it is impossible In this case, by increasing the film thickness, the radiation energy of the laser beam 5 can be sufficiently absorbed, and clear marking becomes possible. As an example, when triiron tetroxide (Fe ₃ O ₄ ) is used as the pigment component, the thickness of the heat generating layer 6 can be about 150 μm.

  When the heat generating layer 6 is black, black absorbs light having a wavelength in the visible region. Therefore, the heat generating layer 6 radiates the laser beam 5 regardless of the visible region of the wavelength of the laser beam 5. Absorbs energy with high efficiency and generates heat. Therefore, regardless of the wavelength (ie, color) of the laser beam 5 of the laser irradiation device 4, the light energy of the laser beam 5 can be efficiently converted into thermal energy, regardless of the laser in any visible wavelength region.

The pigment component of the heat generating layer 6 may be a dye, a pigment, or metal particles or metal oxide particles.
In particular, when the heat generating layer 6 has a black color, a black dye can be used. For example, black of Polylon (trade name) of Tanaka Naoten Co., Ltd., KIWALON POLYESTER MAX-SL of Kiwa Chemical Co., Ltd. (trade name) ) BLACK can be used.

  In the case where a dye or pigment is used for the heat generating layer 6 and the dye has the same color as the dye of the colored layer 7, the heat generating layer 6 is not provided and only the colored layer 7 is configured. it can. That is, the colored layer 7 serves as the heat generating layer 6, and the colored layer 7 absorbs the radiation energy of the laser beam 5 with high efficiency and generates heat.

By including metal particles or metal oxide particles as the dye component of the heat generating layer 6, the heat conductivity of the heat generating layer 6 is improved, which is more preferable. When the thermal conductivity of the heat generating layer 6 is improved, the heat energy generated in the heat generating layer 6 is efficiently transferred to the colored layer 7. That is, the irradiation time of the laser beam 5 is shortened and energy efficiency is improved.
Moreover, the heat transfer area | region 6b of the heat generating layer 6 can be made small because the irradiation time of the laser beam 5 becomes short. Therefore, heat transfer to the boundary surface 7a with the colored layer 7 is also performed in a narrow range, and further, heat transfer to the surface 2a of the thermoplastic resin member 2 is also performed in a narrow range. Thereby, the marking range does not expand with respect to the spot diameter of the laser beam 5, and the marking can be made clear.

In addition, when black metal oxide particles are used as the dye component, the heat generating layer 6 absorbs the radiation energy of the laser beam 5 with high efficiency and generates heat regardless of the wavelength of the laser beam 5 in any visible region. In addition, the heat conductivity of the heat generating layer 6 is improved, and clear marking becomes possible. Examples of black metal oxide particles that can be used include triiron tetroxide (Fe ₃ O ₄ ) and copper oxide.

Further, not only black but also other metal particles or metal oxide particles, γ-Fe ₂ O ₃ , solid solution of γ-Fe ₂ O ₃ and Fe ₃ O ₄ , Co compound deposition type γ-Fe ₂ O ₃ , Co compound-doped γ-Fe ₂ O ₃ , Co compound-coated Fe ₃ O ₄ , Co compound-doped Fe ₃ O ₄ , Co compound-coated γ-Fe ₂ O ₃ and Co compound-coated Fe ₃ O ₄ , solid solution of Co compound doped γ-Fe ₂ O ₃ and Co compound doped Fe ₃ O ₄ , oxide ferromagnetic powder such as CrO ₂ , Fe—Co—Ni alloy, Fe—Al alloy, Mn-Bi alloy, Fe-Al-P alloy, Fe-Co-Ni-Cr alloy, Fe-Ni-Zn alloy, Fe-Co-Ni-P alloy, Fe-Ni alloy, Co-Ni alloy, Co-P Alloy, Fe-Mn-Zn alloy, Fe-Ni-Cr P alloy, can be used powder mainly composed Fe, Ni, and Co.

When the heat generating layer 6 contains metal particles or metal oxide particles, it is preferable to use a small and uniform particle size of the metal particles or metal oxide particles. In addition, it is even better because heat transfer efficiency is improved by using needle-shaped particles of metal particles or metal oxide particles.
By using uniform metal particles or metal oxide particles having a small particle size, the distance between the particles dispersed in the heat generating layer 6 is reduced. As a result, the amount of heat energy absorbed by the binder interposed between the particles can be suppressed, and heat can be efficiently transferred within the heat generating layer 6 with little energy loss.
That is, since the heat energy generated in the heat generating layer 6 is efficiently transferred to the colored layer 7, it contributes to the improvement of the thermal conductivity, the irradiation time of the laser beam 5 can be shortened, and the heat transfer of the heat generating layer 6 The region 6b can be reduced. Therefore, heat transfer to the boundary surface 7a with the colored layer 7 is also performed in a narrow range, and further, heat transfer to the surface 2a of the thermoplastic resin member 2 is also performed in a narrow range. Thereby, the marking range does not expand with respect to the spot diameter of the laser beam 5, and the marking can be made clear.
In order to perform clear marking, the particle diameter of the metal particles or metal oxide particles is preferably 1 μm or less, and more preferably 60 nm or less when fine marking is performed.

In the heat generating layer 6, the pigment component is bound by a binder. As an example of the binder, PVA or a mixture of PVA and glycerin can be used.
Other binders include vinyl chloride copolymers, polyurethane resins, acrylic resins, polyester resins, acrylonitrile-butadiene copolymers, polyamide resins, polyvinyl butyral resins, nitrocellulose, styrene butadiene copolymers. Coalescence, acetal resin, epoxy resin, phenoxy resin, polyether resin, polyimide resin, phenolic resin, polybutadiene elastomer, synthetic rubber resin, and other thermoplastic resins, polycondensation phenol resin, epoxy resin, polyurethane curable resin, Thermosetting of urea resin, butyral resin, polymeric resin, melanin resin, alkyd resin, silicone resin, acrylic reaction resin, polyamide resin, epoxy-polyamide resin, saturated polyester resin, urea formaldehyde resin, etc. It may be used butter, a radiation curable resin or mixtures thereof.
Among these, it is preferable to use one having high thermal conductivity.

(Base sheet)
The colored sheet 1 of the present invention may have a configuration having a transparent base sheet 8 on the surface 6 a of the heat generating layer 6. The base sheet 8 is not particularly limited as long as it is a material that transmits the laser beam 5 with high transmittance. For example, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyamide (PA), and the like. Can be used. Further, the thickness of the base sheet 8 is not particularly limited, but a material having a thickness of about 15 μm can be used.
When the colored sheet 1 is disposed on the surface 2a of the thermoplastic resin member 2, the base sheet 8 side is disposed on the top. The laser beam 5 is transmitted through the transparent base sheet 8 and directly heats the heat generating layer 6 formed on the lower surface of the base sheet 8.

For example, a magnetic tape used for a VHS video tape or the like can be used as the heat generating layer 6 and the base sheet 8 integrated.
The magnetic tape has high thermal conductivity and contains fine magnetic powder. There is also a thing in which the magnetic powder has a needle shape. An example is a magnetic tape containing γ-Fe ₂ O ₃ having a particle size of 60 nm. Further, the thickness of the base tape of the magnetic tape is about 16 μm, which matches the conditions required for the heat generating layer 6 in the present invention.

(Colored sheet manufacturing method)
An example of a method for producing the colored sheet 1 will be described below. In addition, here, it demonstrates using the code | symbol of the said figure with reference to Fig.2 (a)-(d) suitably.
As a preliminary preparation, a dye component mixed solution that becomes the heat generating layer 6 and a dye mixed solution that becomes the colored layer 7 are prepared, and these are sequentially coated on the base sheet 8 to form the heat generating layer 6 and the colored layer 7 to be colored. Sheet 1 can be produced.

First, a dye component mixed solution that becomes the heat generating layer 6 is prepared. A predetermined amount of a dye component is mixed with a mixture of polyvinyl alcohol (3 to 10% aqueous solution) and glycerin (polyvinyl alcohol ratio 0 to 10%) as a binder to obtain a dye component mixture 9. In addition, as a pigment | dye component, what can absorb the radiant energy of the laser beam 5 is used as mentioned above.
The thermal conductivity of the heat generating layer 6 can be increased by increasing the amount of the pigment component relative to the binder. However, if the amount of the dye component is too large relative to the binder, the binder cannot bind the dye component, and the dye component is not fixed. Accordingly, it is desirable that the content ratio is appropriate. For example, when triiron tetroxide is used as the pigment component, the mass ratio of the binder to the pigment component is preferably about 3: 1.
Next, the liquid mixture of the pigment component and the binder is sufficiently stirred, and a degassing process is performed with a vacuum desiccator to remove bubbles in the liquid mixture. By passing through this step, it is possible to remove the air in the dye component mixture and obtain a dye component mixture in which the dye component is uniformly dispersed in the binder.

Next, a dye mixed solution to be the colored layer 7 is prepared. Similar to the process of forming the heat generating layer 6, a dye is mixed with polyvinyl alcohol (8-20% aqueous solution) as a binder.
The dye mixture liquid in which the dye is mixed is sufficiently stirred and deaerated by a vacuum desiccator to remove bubbles in the mixture liquid. By passing through this step, it is possible to remove air in the dye mixture and obtain a dye mixture in which the dye is uniformly dispersed.

Next, a process for producing the heat generating layer 6 and the colored layer 7 having a uniform thickness will be described. In this process, the jig 14 shown in FIG. The jig 14 includes a base plate 12, a pair of film thickness adjusting shims 11 disposed thereon, and a shim restraining plate 10 that holds the film thickness adjusting shims 11.
A film thickness adjusting shim 11 is disposed on the base plate 12 in parallel at a predetermined interval, and the shim suppressing plate 10 is installed so as to expose a part of the opposite side of the film thickness adjusting shim 11. To do. The shim restraining plate 10 serves to hold the film thickness adjusting shim 11.

A process of forming the heat generating layer 6 on the base sheet 8 will be described. As shown in FIG. 4B, the base sheet 8 is disposed on the base plate 12 of the jig 14 between the opposing film thickness adjusting shims 11, and a sufficient amount of the dye is formed on the base sheet 8. The component mixture 9 is simply applied.
Next, as shown in FIG. 4 (c), the coating plate 13 is disposed on the upper surface of the film thickness adjusting shim 11 and exposed from the shim restraining plate 10, and in front of FIG. 4 (c). The coating component 13 is slid once to several times from the back to the back or from the back to the front, so that the pigment component mixture 9 simply applied on the base sheet 8 is leveled and the film thickness is adjusted. The heat generating layer 6 having a film thickness corresponding to the thickness of the shim 11 can be formed.

Further, the base sheet 8 uniformly coated with the dye component mixture 9 produced in the step shown in FIG. 4C is dried at 40 ° C. for about 30 minutes. As a result, the moisture in the pigment component mixed solution 9 is removed, and the heat generating layer 6 is fixed to the base sheet 8.
In addition, you may perform the said drying process by dehumidification by vacuum deaeration. The heat generating layer 6 is formed by the above process.

  Next, using the same jig 14 as in the method for producing the heat generating layer 6, through the same process, the dye mixture is uniformly applied on the heat generating layer 6 and dried at 40 ° C. for about 30 minutes. The water in the dye mixture is removed, and a colored layer 7 is formed on the heat generating layer 6. In addition, you may perform the said drying process by dehumidification by vacuum deaeration.

(Laser marking device)
The laser irradiation device 4 that is a light source of the laser beam is preferably a compound semiconductor laser. As the compound semiconductor laser, an inexpensive laser having an output of about 100 to 350 mW and using a GaAs compound semiconductor or the like can be used.
FIG. 5 shows a basic configuration of the laser irradiation apparatus 4. The laser irradiation device 4 converts the diffused light emitted from the laser oscillator 4d into parallel light by the collimator lens 4b, precisely condenses the parallel light by the subsequent condenser lens 4a, and irradiates the target irradiation target W. To do.
As the laser oscillator 4d, for example, a laser diode that oscillates a red laser having a wavelength of 670 nm can be used. The laser oscillator 4d is connected to a control unit 4c having a laser driver and a temperature controller.

The laser irradiation device 4 irradiates the surface of the irradiation target W with the spot region S. The shape of the spot region S of the laser irradiation device 4 includes a circular shape and an elliptical shape depending on the type of the laser irradiation device 4. Since the shape of the spot region S is substantially similar to the shape to be marked, for example, when the marking shape is to be circular, the laser irradiation device 4 having a circular spot shape is used, or the spot shape is circular. Correction is necessary.
Further, the laser irradiation device 4 can narrow the spot area S to a minimum of 0.1 mm.
As an example of the laser irradiation apparatus, HL65545MG manufactured by OPENEXT can be used.

(Marking method)
FIG. 1 shows a marking processing method of this embodiment.
In the marking processing method, the above-described colored sheet 1 is disposed on the thermoplastic resin member 2 to be marked, and the surface 1a of the colored sheet 1 is irradiated with a laser beam 5 by a laser irradiating device 4, thereby the thermoplastic resin. It has the structure which fixes a dye to the surface part of a resin member, and performs marking.

  The thermoplastic resin member 2 to be marked is placed on the XY table 3 with the marking target portion of the thermoplastic resin member 2 facing up. The XY table 3 can freely move relative to the laser irradiation device 4 installed above the XY table 3 in a predetermined range on a horizontal plane. The X-Y table 3 and the laser irradiation device 4 are relatively operated, and the spot region S of the laser beam 5 is set to a portion where the marking of the thermoplastic resin member 2 is performed, so that the thermoplastic resin member 2 is placed at a predetermined position. Marking can be performed.

  The laser irradiation device 4 includes a Z stage (not shown) operable in the vertical direction, and the focal distance is adjusted by adjusting the distance between the laser irradiation device 4 and the thermoplastic resin member 2. The size of the spot area S can be appropriately adjusted by matching with the upper surface of the colored sheet 1 disposed on the member 2.

The colored sheet 1 is arranged in a necessary and sufficient size on the marking target portion of the thermoplastic resin member 2. When arranging, it arrange | positions so that the colored layer 7 side may contact the thermoplastic resin member 2 among the colored layer 7 and the heat generating layer 6 of the colored sheet 1.
By irradiating the surface 1 a of the colored sheet 1 with the laser beam 5 for a predetermined time, the marking having a shape similar to the spot diameter can be performed on the thermoplastic resin member 2. Further, a line can be drawn by relatively moving the XY stage and the laser irradiation device 4 at a constant speed while irradiating the laser beam 5.

The irradiation time of the laser beam 5 is set to about 100 ms in order to fix the dye to the thermoplastic resin member 2, and is preferably 65 ms, more preferably 15 ms in consideration of production efficiency.
By these marking processing methods, markings are made on the surface of the thermoplastic resin member 2, and the part number for reliably identifying the part and the manufacturing date for ensuring the traceability of the part are character strings. Or it is marked as a two-dimensional code.
In the case of marking a two-dimensional barcode, the size of each dot is about 0.2 mm to 0.3 mm.

The thermoplastic resin member 2 to be marked may have a curved surface as long as the colored sheet 1 can be arranged following the thermoplastic resin member 2.
FIG. 6 shows a marking processing method when the thermoplastic resin member 22 to be marked has a curved surface. When the thermoplastic resin member 22 has a curved surface, the distance between the laser irradiation device 4 and the thermoplastic resin member 22 when the XY stage and the laser irradiation device 4 are relatively moved is not constant. Therefore, when the XY stage and the laser irradiation device 4 move relative to each other, the distance between the laser irradiation device 4 and the thermoplastic resin member 22 is adjusted by a Z stage (not shown) provided in the laser irradiation device 4. There is a need to. Further, when drawing a line, the XY stage and the Z stage are operated in synchronization according to the curved surface shape of the thermoplastic resin member 22.

  With the above configuration, the laser beam 5 is absorbed in the heat generating layer 6 and converted into thermal energy, and does not depend on the spectral transmittance of the target thermoplastic resin members 2 and 22. Therefore, it is not necessary to adjust the wavelength appropriately according to the material of the thermoplastic resin members 2 and 22, and the apparatus can be simplified.

  Further, in order to perform laser irradiation on the heat generating layer 6 containing black particles, even when the laser beam 5 has a wavelength in the visible light region, the surface of the thermoplastic resin members 2 and 22 is dyed with the same color as the laser beam 5. 2a and 22a can be melt-fixed.

  Furthermore, by having the configuration in which the colored sheet 1 is arranged on the thermoplastic resin members 2 and 22, if the colored sheet 1 can be arranged following the thermoplastic resin members 2 and 22, marking on the curved surface is also possible. Become.

  In addition, since the colored layer 7 is formed on the colored sheet 1, the target thermoplastic resin members 2, 22 do not diffuse even if the compatibility with the dye is poor, and clear. Marking is possible.

The features of the present invention will be described more specifically with reference to the following examples. However, the scope of the present invention is not limited to the examples.
Sample No. having the configuration described in Table 1 was used. The colored sheets of Examples 1 to 11 and Comparative Examples were produced. Hereinafter, each configuration will be specifically described.
A base sheet made of transparent polypropylene and having a thickness of 16 μm was used. This base sheet has a high transmittance and transmits a laser beam.
The heat generating layer used black dye, black pigment, iron trioxide, cobalt oxide or copper oxide as a pigment component. In addition, PVA was used as a binder to combine the dye components to form a heat generating layer. As the film thickness of the heat generating layer, those shown in Table 1 were used for each sample.
Sample No. As the colored sheets of Examples 1 and 11, a magnetic tape of VHS video tape HG (VHS) (product name) manufactured by TDK Corporation was used on the assumption that the heat generating layer and the base sheet were integrated. The magnetic tape has a thickness of 5 μm, and the particle diameter of the contained particles is about 60 nm.
Sample No. The colored sheets of Comparative Examples 8 and 9 do not have a heat generating layer and are composed of only a base sheet and a colored layer.
As a dye for the colored layer, red Polylon (trade name) from Tanaka Nao Dye Store Co., Ltd. was used, and a mixture of PVA and glycerin was used as a binder. As the thickness of the colored layer, those described in Table 1 were used for each sample.

  HL6545MG (continuous operation output 120 mW, laser beam wavelength 660 nm, single mode) manufactured by OPENEXT was used as the laser irradiation apparatus. The spot shape was a circle, the spot diameter was φ0.2 mm, the laser output was 170 mA, and the laser beam was irradiated for 200 ms.

  Sample No. The state of the surface of the base material marked with the colored tape 1 is shown in FIG. Referring to FIG. 7, marking with a size of about φ0.2 mm, which is substantially the same as the spot diameter of the laser beam, could be performed. It was also confirmed that substantially uniform coloring was performed inside the marked area.

Marking is evaluated visually by magnifying the marking part with a microscope and visually observing, x for uncolored, △ for unclear but colored, and clear for non-uniform. Evaluation was performed in four stages, with ◯ being colored as ◯ and clear and uniformly colored as being ◎ (that is, equivalent to the colored state shown in FIG. 7). After the laser irradiation, the marking surface was wiped with ethyl alcohol and then observed.
Table 1 shows details and determination results of each example and comparative example.

Referring to Table 1, sample No. which is an example. Samples Nos. 1-6, 10 and 11 were colored although there was a difference in marking quality. In 7 to 9, the base material was not colored.
Sample No. which does not constitute a heat generating layer In the comparative examples 8 and 9, since the base sheet transmits the laser beam, the red colored layer is directly irradiated with the laser beam, so that the radiation energy of the laser beam cannot be absorbed and the marking cannot be performed. .

In addition, Sample No. with a heat generation layer containing copper oxide was formed. In the comparative example of No. 7, since the heat generating layer is gray, it is considered that the radiation energy of the laser beam could not be sufficiently absorbed and the marking could not be performed.
For these comparative examples, sample no. In the examples of 1 to 6, 10, and 11, since the heat generating layer is black or dark gray, it absorbs the radiation energy of the laser beam, converts it into heat energy, and transfers heat related to the colored layer. It is considered that marking was possible because it was made.

However, even in the examples, the sample Nos. Containing cobalt oxide in the heat generating layer. No. 6 is disadvantageous in that the color of the heat generating layer is dark gray and the radiation energy is absorbed with respect to black. As a result, it is considered that the marking is relatively unclear.
Sample No. For the colored tapes of the examples having the heat-generating layer containing 4 or 5 iron trioxide, sample no. 4 has a thickness of 70 μm. The film thickness of 5 is 150 μm. In forming the heat generating layer, triiron tetroxide becomes light black (gray) at 70 μm and black at 150 μm. Therefore, it is considered that the absorption of the red laser is weak at 70 μm iron trioxide and becomes Δ as a marking result, and at 150 μm, the marking result is ○.

  Sample No. 1 and sample no. Comparing the 11 examples, both use magnetic tape as the heat generating layer. 1 is ◎, sample no. 11 is Δ. This is because the film thickness of the colored layer is Sample No. In No. 11, since it is a thick film with a thickness of 40 μm, it is considered that in the heat transfer process transmitted from the colored layer to the thermoplastic resin member, the thermal energy diffuses and the marking becomes unclear.

1a, 2a, 6a ... surface 2, 22 ... thermoplastic resin members 2b, 6b, 7b ... heat transfer region 2c ... molecular lattice 3 ... XY table 4 ... laser irradiation device 4a ... condensing lens 4b ... collimating lens 4c ... Control unit 4d ... Laser oscillator 5 ... Laser beam 6 ... Heat layer 7 ... Colored layer 7a ... Interface 8 ... Base sheet 9 ... Dye component mixture 10 ... Plate 11 ... Thickness adjusting shim 12 ... Base plate 13 ... Coating plate 14 ... Jig S ... Spot area W ... Target

Claims (6)

A colored sheet used when performing marking processing to irradiate a laser beam toward the surface of the thermoplastic resin member and fix the dye to the irradiation position of the laser beam,
A heat generating layer that generates heat by absorbing radiation energy of the laser beam by the irradiation of the laser beam; and
Having a structure in which a colored layer containing a dye to be fixed on the surface of the thermoplastic resin member is laminated;
Said colored layer side being in contact with the surface of the thermoplastic resin member, wherein the irradiation of the laser beam from the heating layer side, Rutotomoni the heat to melt the dye of the colored layer by heat generated in the heat generating layer A colored sheet , wherein the surface of the plastic resin member is softened so that the dye of the colored layer can be fixed to the surface of the thermoplastic resin member.   The colored sheet according to claim 1, wherein the heat generating layer has a black color.   The colored sheet according to claim 1, wherein the heat generating layer contains metal particles or metal oxide particles.   The colored sheet according to claim 1, wherein the colored layer has a thickness of 30 μm or less.   The colored sheet according to any one of claims 1 to 4, wherein the dye of the colored layer is a fluorescent paint. A marking method for irradiating a laser beam toward the surface of a thermoplastic resin member and fixing a dye to the irradiation position of the laser beam,
A colored sheet having a structure in which a heat generating layer that generates heat upon irradiation with the laser beam and a colored layer containing a dye to be fixed on the surface of the thermoplastic resin member is laminated, and the colored layer side is the surface of the thermoplastic resin member A step of placing the device in contact with the
The laser is irradiated from the heating layer side, said surface of the heat generated in the heating layer is melted dye in the colored layer Rutotomoni the thermoplastic resin member is softened, the thermoplastic dye of the colored layer a step of fixing the surface of the resin member seen including,
The marking processing method , wherein the laser beam has an output capable of heating the thermoplastic resin member to a softening point by heat generation of the heat generating layer by irradiation of the laser beam .