JP2013001087A - Transparent laser marking sheet and laser marking method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayer sheet in which a sheet having a laser marking function includes an ink receiving layer, which is superior in color printing aptitude by a sublimation type direct heat transfer method or a sublimation type indirect heat transfer method, with which high contrast and clear characters, symbols, and images can be obtained by laser marking, which has all of a heat fusion property, transparency, a sheet conveying property, a separating property from a die after heat press, heat resistance, bendability, and abrasion resistance, and which is suitable for electronic passports and plastic cards.SOLUTION: The transparent laser marking sheet includes an ink receiving layer forming agent containing polyester resin having a vinyl chloride-based copolymer or a specific functional group on at least one surface of a base material sheet composed of a single layer sheet having a transparent polycarbonate resin composition containing a laser light energy absorbing body, or a multilayer sheet having a skin layer and a core layer.

Description

  The present invention relates to a transparent laser marking sheet and a laser marking method. In particular, the present invention relates to a transparent laser marking sheet excellent in color printing suitability by a sublimation thermal transfer method and marking characteristics by laser marking, and a laser marking method. The present invention also relates to a transparent laser marking sheet and a laser marking method that can be suitably used for plastic cards or electronic passports.

  As international exchange progresses, the movement of people is becoming more active across countries. As a means of identifying individuals and verifying their identity or identity, ID cards with personal information or ID cards such as passports are used. (Identity certificate) etc. are used. In particular, the importance of ID cards issued by public institutions and highly reliable organizations is increasing.

  After the September 2001 terrorist attacks in the United States, measures such as stricter immigration control have been taken in each country. For example, the United States specialized organization ICAO (International Civic Aviation Organization) has established a standard and has started to introduce an electronic passport that incorporates an IC chip capable of writing and reading personal information.

  On the other hand, a plastic card incorporating an IC chip can record a large amount of information as compared to a magnetic card, and has the advantage that it is not easily counterfeited or tampered with. Therefore, a cash card, credit card, prepaid card, electronic Widely used for money cards, ETC cards, various membership cards, employee ID cards, student ID cards, transportation commuter passes, etc.

  In electronic passports or plastic cards that incorporate such various IC chips, information such as personal names, symbols, characters, photographs, designs, etc. is displayed on the card body, etc., in addition to the IC chip in which personal information is written. It is common and plays a central role in the identity authentication process, bringing convenience to people's lives.

  By the way, the above-mentioned electronic passport can identify and prove an individual, so that a third party other than the country or a designated or agency of the country can easily forge or alter personal information. In other words, its reliability is low, and it may interfere with the progress of international exchange and the movement of people on a global scale.

  Therefore, in the above-mentioned electronic passport, or a plastic card such as an IC card or an ID card, prevention of tampering and forgery is an important problem. In other words, providing a clear display with high contrast to plastic cards such as electronic passports, IC cards, ID cards, etc. is extremely effective in terms of physical specifications of the card itself from the viewpoint of preventing counterfeiting and tampering. It is considered important.

  For such a problem, a sheet for laser marking, which gives a laser mark function to the sheet itself constituting the card and can laser mark personal names, symbols, characters, photographs, designs, etc., has been attracting attention, for example, There exist the following patent documents 1-2. Further, there are the following Patent Documents 3 to 4 as IC card sheets capable of performing color printing of characters, symbols, images, designs and the like.

  Patent Document 1 describes a card oversheet formed of at least three layers having skin layers on both sides of a core layer. The skin layer of this card oversheet is formed of a non-crystalline aromatic polyester resin and a lubricant. The core layer is formed of a polycarbonate resin and a laser light energy absorber. Further, the total thickness of the three-layer sheet and the ratio of the thickness of the core layer to the total thickness of the three-layer sheet are defined.

  In Patent Document 2, a surface layer formed from a thermoplastic resin such as polycarbonate or polyethylene terephthalate and an inner layer formed from a polycarbonate, an energy absorber, and a colorant are formed by melt coextrusion. A multilayer sheet for laser marking is disclosed.

  Furthermore, Patent Document 3 describes an IC card core sheet formed from a sheet made of a copolymerized polyester resin composition obtained by substituting a specific amount of an ethylene glycol component with cyclohexanemethanediol, and an oversheet. Yes. Further, it is disclosed that one side of the sheet is embossed.

  Patent Document 4 discloses a non-stretched polyester resin composition comprising two kinds of polyesters having different molar ratios of ethylene glycol units and 1,4-cyclohexanedimethanol units, and an aromatic polycarbonate. A sheet for an identification card on which one side is matted is described.

Japanese Patent No. 4142086 Japanese Patent No. 4379668 JP-A-9-66590 JP-A-11-100451

  Certainly, in the card oversheet in Patent Document 1, the oversheet can be marked without damage by irradiation of laser light energy, and the contrast between the fabric portion and the print portion is high, and clear characters, symbols, and images are displayed. Obtained and excellent in heat resistance. However, the outermost skin layer of the sheet is formed of a non-crystalline aromatic polyester resin and a lubricant. For this reason, it is difficult to perform color printing of characters, symbols, images, designs, and the like excellent in color development and sharpness on the skin layer by color printing by the sublimation type direct thermal transfer method or the sublimation type indirect heat transfer method.

  The multilayer sheet for laser marking disclosed in Patent Document 2 has good laser marking properties. However, as in Patent Document 1, the surface layer is formed of a thermoplastic resin such as polycarbonate or polyethylene terephthalate. Therefore, it is difficult to record characters, symbols, images, designs, and the like excellent in color development and sharpness on this surface layer by color printing by the sublimation type direct thermal transfer system or the sublimation type indirect thermal transfer system.

  Furthermore, in the IC card of Patent Document 3, the means for imparting printing aptitude such as printing ink adhesiveness, ink fillability, and printing machine aptitude is by embossing. In the embossing, a certain degree of printing machine suitability can be obtained, but the color reproducibility and sharpness of color printing by the sublimation type direct thermal transfer method or the sublimation type indirect heat transfer method are inferior. Even if color printing is possible, the printing is easily peeled off. The IC card disclosed in Patent Document 3 is obtained by fusing an oversheet and a core sheet and having an IC chip mounting module disposed therein, and does not have a laser marking function. The information is only printed and may be inferior in tampering prevention and counterfeiting prevention.

  In addition, in the identification card of Patent Document 4, as in Patent Document 3, the provision of printing aptitude such as printing ink adhesion, ink landing finish, and printing machine suitability was simply formed on the surface of the polyester resin sheet. This is due to embossing. In the embossing, a certain degree of printability can be obtained as in Patent Document 3, but the color reproducibility and sharpness of color printing by the sublimation type direct thermal transfer method or the sublimation type indirect heat transfer method are inferior. There is also a problem that printed characters, designs, etc. are easily peeled off. Further, the IC card of Patent Document 4 is formed by fusing an oversheet and a core sheet, and an IC chip mounting module is disposed therein. Therefore, like the IC card described in Patent Document 3, it does not have a laser marking function. The information is only printed and has a problem that it is inferior in tampering prevention and counterfeiting prevention.

  The present invention has been made to solve the above-described problems, and can provide a transparent laser marking sheet and a laser marking method that have printability, adhesion, and transparency. Further, a transparent laser marking sheet having an ink receiving layer provided on at least one side of a substrate sheet is extremely excellent in color printability by a sublimation type direct thermal transfer method or a sublimation type indirect heat transfer method. Further, the ink receiving layer is firmly adhered to the base material sheet and does not peel off or deteriorate. Furthermore, the transparent laser marking sheet can mark information such as characters, symbols, and images without being damaged by the irradiation of laser light energy. Moreover, it is possible to provide a transparent laser marking sheet and a laser marking method in which a contrast between the base sheet (background portion) and the marked information portion is high and a clear marking can be obtained. In addition, the transparent laser marking sheet, which has sheet transportability, releasability from the mold after hot pressing, has heat resistance, bending resistance, wear resistance, and is excellent in prevention of tampering and forgery, And a laser marking method.

  Furthermore, the laser marking can provide a high-contrast and clear display, and can provide a plastic card and an electronic passport that are excellent in preventing falsification and forgery.

  The present invention provides the following transparent laser marking sheet and laser marking method.

[1] A transparent laser marking sheet provided with an ink receiving layer on at least one side of a transparent base sheet for laser marking, wherein the transparent base sheet is based on 100 parts by mass of a transparent resin mainly composed of a polycarbonate resin. A single layer sheet having a thickness of 50 to 200 μm and a total light transmittance of 70% or more, or a skin layer. The skin layer is a transparent resin layer mainly composed of an amorphous aromatic polyester resin, the core layer being formed from at least three sheets that are coextruded by a melt coextrusion method. The layer is a laser light energy absorber 0.0005 with respect to 100 parts by mass of the transparent resin mainly composed of polycarbonate resin. As a multilayer sheet having a transparent polycarbonate resin composition layer containing 1 part by mass, having a total sheet thickness of 50 to 200 μm, a thickness ratio of 20 to 80% with respect to the total thickness of the core layer, and a total light transmittance of 70% or more. The ink receiving layer is made of a vinyl chloride copolymer or a polyester-based resin having a functional group, and a dry film thickness is formed on one side of the single-layer sheet or multilayer sheet with a solvent or a solution using water as a medium. Is a transparent laser marking sheet configured as a layer having a thickness of 1 to 20 μm.

[2] The transparent laser marking sheet according to [1], wherein the laser light energy absorber of the transparent laser marking sheet contains one or more selected from carbon black, titanium black, and metal oxide. .

[3] The single-layer sheet is a transparent polycarbonate resin composition comprising 100 parts by weight of a transparent resin mainly composed of a polycarbonate resin and 0.01 to 3 parts by weight of a lubricant, and further, an antioxidant and / or an anti-coloring agent. The transparent laser marking sheet according to [1] or [2], comprising 0.1 to 5 parts by mass of an agent and 0.1 to 5 parts by mass of an ultraviolet absorber and / or a light stabilizer.

[4] A non-crystalline aromatic polyester resin composition in which the skin layer constituting the multilayer sheet is composed of 100 parts by mass of a transparent resin mainly composed of non-crystalline aromatic polyester resin and 0.01 to 3 parts by mass of a lubricant. [1] or [2] further comprising 0.1 to 5 parts by mass of an antioxidant and / or anti-coloring agent and 0.1 to 5 parts by mass of an ultraviolet absorber and / or a light stabilizer. ] The transparent laser marking sheet of description.

[5] Any of [1] to [4] above, wherein the melt volume rate measured according to ISO 1133 of the polycarbonate resin constituting the core layer of the single layer sheet and the multilayer sheet is 4 to ³⁰ cm 3/10 minutes. The transparent laser marking sheet according to Crab.

[6] The copolymerization ratio of vinyl chloride and other monomers in the vinyl chloride copolymer is at least 30% by mass of vinyl chloride and the average degree of polymerization of 100 to 2000 is the above [1] to [5] The transparent laser marking sheet according to any one of the above.

[7] A copolymer component other than vinyl chloride in the vinyl chloride copolymer is vinyl ester, acrylic acid, methacrylic acid, acrylic ester, methacrylic ester, olefin, acrylonitrile, styrene, vinylidene chloride, vinyl ether, and aromatic The transparent laser marking sheet according to any one of [1] to [6], which is one or more selected from vinyl compounds.

[8] The transparent laser marking sheet according to any one of [1] to [7], wherein the polyester resin having the functional group is a polyester resin having a sulfonate group or a carboxylate group.

[9] The transparent laser marking sheet according to any one of [1] to [8], which is for a plastic card.

[10] The transparent laser marking sheet according to any one of [1] to [8], which is for an electronic passport.

[11] A method for performing color printing and laser marking on a transparent laser marking sheet provided with the ink receiving layer according to any one of [1] to [10], wherein the ink receiving layer of the transparent laser marking sheet comprises: After color printing is performed on the formed surface by a sublimation type direct thermal transfer method or a sublimation type indirect thermal transfer method, laser light energy is irradiated from the surface on which the ink receiving layer is provided, and characters, figures, symbols, or information are displayed. Laser marking method for laser marking.

  ADVANTAGE OF THE INVENTION According to this invention, the outstanding effect that the transparent laser marking sheet and laser marking method which have printability, adhesiveness, and transparency can be provided can be show | played. In particular, the color printing suitability by the sublimation type direct thermal transfer method or the sublimation type indirect heat transfer method is extremely excellent, and the printing suitability is excellent such that there is no color distortion and color blur and printing having a good density can be performed. Further, the ink receiving layer is firmly adhered to the base material sheet and does not peel off or deteriorate. Furthermore, the transparent laser marking sheet can mark information such as characters, symbols, and images without being damaged by the irradiation of laser light energy. In addition, it is possible to provide a transparent laser marking sheet and a laser marking method in which the contrast between the non-marking portion (background portion) of the sheet and the marked information portion is high and a clear marking can be obtained. In addition, it has good sheet transportability, release properties from the mold after hot pressing, heat resistance, bending resistance, wear resistance, excellent anti-tampering and anti-counterfeiting, transparent laser marking Sheets and laser marking methods can be provided.

It is the schematic diagram which shows one Embodiment of the transparent laser marking sheet of this invention, Comprising: It is the figure which showed typically the cross section of the laser marking sheet which provided the ink receiving layer in the single side | surface of the base material sheet which consists of a single layer. It is a schematic diagram showing another embodiment of the transparent laser marking sheet of the present invention, schematically showing a cross section of a laser marking sheet provided with an ink receiving layer on one side of a base material sheet having a skin layer and a core layer. It is a figure. It is the usage example schematic diagram which shows one Embodiment of the transparent laser marking sheet of this invention, Comprising: It is the figure which showed typically the cross section of the usage example to a plastic card. It is the usage example schematic diagram which shows one Embodiment of the transparent laser marking sheet of this invention, Comprising: It is the figure which showed typically the cross section of the usage example (IC chip type) to the data page for electronic passports. It is the usage example schematic diagram which shows one Embodiment of the transparent laser marking sheet of this invention, Comprising: It is the figure which showed typically the cross section of the other usage example (IC chipless type) to the data page for electronic passports.

  Hereinafter, embodiments for carrying out the transparent laser marking sheet and the laser marking method of the present invention will be specifically described. However, the present invention broadly includes a transparent laser marking sheet and a laser marking method having the invention-specific matters, and is not limited to the following embodiments.

[1] Configuration of the transparent laser marking sheet of the present invention:
A transparent laser marking sheet in which an ink receiving layer is provided on at least one side of a transparent base sheet for laser marking, wherein the transparent base sheet is a laser with respect to 100 parts by weight of a transparent resin mainly composed of a polycarbonate resin. As a single-layer sheet comprising a transparent polycarbonate resin composition containing 0.0005 to 1 part by mass of a light energy absorber and having a thickness of 50 to 200 μm and a total light transmittance of 70% or more, or a skin layer and a core layer. The skin layer is a transparent resin layer mainly composed of an amorphous aromatic polyester resin, and the core layer is formed from at least three layers coextruded by a melt coextrusion method. Laser light energy absorber 0.0005-1 quality with respect to 100 parts by mass of transparent resin mainly composed of polycarbonate resin Part of a transparent polycarbonate resin composition, comprising a sheet having a total thickness of 50 to 200 μm, a thickness ratio of the core layer to the total thickness of 20 to 80%, and a total light transmittance of 70% or more. The Further, the ink receiving layer is made of a vinyl chloride copolymer or a polyester-based resin having a functional group, and a dry film thickness is formed on one side of the single-layer sheet or the multilayer sheet with a solvent or a solution using water as a medium. It is configured as a layer having a thickness of 1-20 μm.

[1-1] Ink receiving layer:
The ink receiving layer in the transparent laser marking sheet of the present invention is formed in a layered manner on at least one side of the substrate sheet. Further, the receiving layer is formed from a vinyl chloride copolymer or a polyester-based resin having a functional group, and has a dry film thickness of 1 to 20 μm. By forming in this way, color printing can be performed on the ink receiving layer provided on the transparent laser marking sheet by, for example, a sublimation type direct thermal transfer method or a sublimation type indirect heat transfer method. Color-printed characters and designs have no color blurring or color distortion, and are excellent in density reproducibility. In addition, it is possible to form an ink receiving layer that adheres firmly to the base sheet and does not peel off or change in quality. Laser marking is excellent in preventing falsification and counterfeiting, but cannot meet the demand for color images because it is monochromatic (white or black). However, by using a transparent laser marking sheet provided with such an ink-receiving layer, in addition to laser marking for preventing falsification and forgery, a color image can be formed on a plastic card or an electronic passport described later. it can.

  This ink receiving layer is made of a vinyl chloride copolymer or a polyester-based resin having a functional group, and is coated on one side of the transparent laser marking sheet with a solvent or water-based solution to a dry film thickness of 1 to 20 μm. It is made. By providing such an ink-receiving layer, there is no color blur or color distortion, excellent print reproducibility, excellent adhesion to the substrate, and does not impair the sharpness of marking during laser marking, or characters , Graphics, symbols, etc. can be clearly and reliably visible without so-called blurring.

  Moreover, the ink receiving layer in the transparent laser marking sheet of the present invention is configured as a layer having a dry film thickness of 1 to 20 μm. By providing such a desired thickness, the ink receiving layer does not need to be excessively thick. Furthermore, it can have sufficient printability, and it corresponds to a general thickness standard required for an electronic passport or a plastic card. That is, there is an advantage that it becomes easy to form an electronic passport or a plastic card using a transparent laser marking sheet having such a desired ink receiving layer. Furthermore, when the ink receiving layer is within the above-described desired thickness range, it is possible to ensure the clarity of characters, figures, symbols and the like when laser marking or printing is performed. On the other hand, if the thickness of the ink receiving layer is less than 1 μm, it is difficult to obtain sufficient printability. By reducing the adhesion between the printing ink and the base material, for example, characters and designs by sublimation type direct thermal transfer method or sublimation type indirect thermal transfer method, etc., color blurring and color torsion, density reproduction It becomes inferior to sex. On the other hand, when the thickness of the ink receiving layer exceeds 20 μm, the average thickness of the transparent laser marking sheet is originally about 80 to 120 μm, and the total thickness of the transparent laser marking sheet provided with the ink receiving layer is excessive. For example, in the case of a plastic IC card, the thickness of the entire card is defined by ISO, which is not preferable because it exceeds the thickness. Moreover, even if it is too thick, it is difficult to obtain printability commensurate with it.

  Here, the “ink-receiving layer made of a vinyl chloride copolymer or a polyester-based resin having a functional group” is transparent when applied to a substrate, and has excellent fixability of printing ink. The target printing method includes a sublimation type direct thermal transfer method or a sublimation type indirect heat transfer method, and various printing methods such as an ink jet method and an offset printing method can be targeted.

  The vinyl chloride copolymer has a copolymerization ratio between vinyl chloride and another monomer of at least 30% by mass of vinyl chloride and an average degree of polymerization of 100 to 2000, and the vinyl chloride copolymer other than vinyl chloride. The copolymerization component is one or more selected from vinyl esters, acrylic acid, methacrylic acid, acrylic esters, methacrylic esters, olefins, acrylonitrile, styrene, vinylidene chloride, vinyl ethers, and aromatic vinyl compounds.

  The ratio (ratio) of vinyl chloride in the vinyl chloride copolymer is 30% by mass or more, preferably 50% by mass or more. This ratio is 30% by mass or more, preferably 50% by mass or more even in the case of binary copolymers and ternary or higher multi-component copolymers. Here, the vinyl chloride component contributes to fixing of printing ink (ink acceptance), and the other components contribute to solubility in organic solvents, dispersion stability of polymer droplets in water, and adhesion to the substrate. Therefore, by setting it to 30% by mass or more, especially by direct thermal transfer printing, it has excellent adhesion to the substrate, color development and sharpness, characters, symbols, images, and designs. Color printing can be performed. On the other hand, when the ratio of vinyl chloride is less than 30% by mass, it is difficult to obtain good printability. In addition, it is preferable that the upper limit of content of a vinyl chloride component is 85 mass%. If the vinyl chloride component content is too high, the copolymer component content will be low, the solubility in organic solvents will be difficult, the film formability during coating will be poor, and the adhesion to the substrate will be poor. Since it is inferior in property, formation of the ink receiving layer on the substrate is hindered.

  The average degree of polymerization of the vinyl chloride copolymer forming the ink receiving layer is preferably 100 to 2000. An ink receiving layer containing a vinyl chloride copolymer having such a degree of polymerization is excellent in printability and also has good adhesion to a substrate sheet. Furthermore, if the degree of polymerization is too low such that the average degree of polymerization is less than 100, the cohesive force of the ink-receiving layer becomes small and the printed layer becomes brittle, which is not preferable because cracking or peeling of the printed layer occurs. On the other hand, a vinyl chloride copolymer having an average degree of polymerization of more than 2000 is inferior in suitability for coating because it is poor in solubility in an organic solvent or in dispersion stability in water. It cannot be formed properly and does not function as an ink receiving layer.

  Here, the average degree of polymerization is a value representing how many monomers are polymerized to form a copolymer. The total number of molecules of vinyl chloride and the copolymer components other than vinyl chloride that form a vinyl chloride copolymer formed by polymerization of vinyl chloride and a copolymer component other than vinyl chloride is the number of molecules of the vinyl chloride copolymer. The value divided by. The average degree of polymerization refers to the number average degree of polymerization.

  Examples of the vinyl chloride copolymer that forms the ink receiving layer include vinyl chloride-olefin copolymers such as vinyl chloride-ethylene copolymer, vinyl chloride-propylene copolymer, vinyl chloride-isobutylene copolymer, Halogenation of vinyl chloride-propylene copolymers such as vinyl chloride-vinylidene chloride copolymer, vinyl chloride-vinyl fluoride copolymer, vinyl chloride-vinyl bromide copolymer, vinyl chloride-propylene chloride copolymer, etc. Olefin copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl ester copolymer such as vinyl chloride-vinyl stearate copolymer, vinyl chloride-acrylic such as vinyl chloride-acrylic copolymer, or acrylic -Based derivative copolymer, ethylene-vinyl chloride-vinyl acetate copolymer, ethylene-vinyl chloride-acrylic Ethyl copolymer, methyl methacrylate - butadiene - styrene - may be mentioned 3-way, or quaternary copolymer of vinyl chloride copolymer. The copolymer structure of the vinyl chloride copolymer may be a block copolymer, a graft copolymer, or a random copolymer.

  On the other hand, examples of the polyester resin having a functional group include an aqueous polyester resin containing a sulfonate group or a carboxylate group. Furthermore, these water-based polyester resins and vinyl-based monomer emulsion polymerization emulsions, water-dispersible resin compositions of these water-based polyester resins and copolymerized acrylic resins, these water-based polyester resins and water-based urethane resins and polyvinyl alcohol (hereinafter, An aqueous solution obtained by graft polymerization of a hydrophilic radically polymerizable vinyl monomer and other vinyl monomers in the presence of a mixed aqueous solution, aqueous dispersion, or mixed aqueous solution or aqueous dispersion thereof. Examples thereof include mixed aqueous solutions and aqueous dispersions of a modified cationic polymer obtained by mixing a graft copolymer, a vinyl copolymer having a side chain cationic quaternary ammonium base, and PVA.

  Examples of the sulfonate group, which is a functional group of the polyester resin, include groups in which protons of the sulfonate group are substituted with other cations (for example, metal ions, organic onium ions, etc.). Needless to say, is not limited to monovalent ions, but may be divalent or higher ions. Furthermore, examples of the carboxylate group include groups in which a hydrogen atom of a carboxyl group is substituted with another cation.

  The above-mentioned polyester-based resin having a sulfonate group can be obtained, for example, by polymerizing a polyester-based resin and then copolymerizing a dicarboxylic acid or glycol containing a sulfonate group such as a metal salt of sulfonic acid. A polyester resin having a carboxylate group can be obtained by a method in which an acid anhydride is reacted with a polyester resin, a carboxyl group is introduced, and then neutralized with an alkali compound or the like to obtain a carboxylate.

  Further, in order to perform suitable coating and drying on the substrate sheet, a coating agent (vinyl chloride copolymer or polyester resin having a functional group) for forming an ink receiving layer is used as an organic solvent solution, an aqueous solution or an organic solvent. Used as a mixed aqueous solution of solvent and water. By being configured as a solvent solution, an aqueous solution, or a mixed aqueous solution in this way, it becomes easy to apply a thin coating on the surface of the substrate when applying to the substrate sheet, and it is easy to adjust the thickness of the ink receiving layer. Become.

  An organic solvent that can be used by dissolving a copolymer or a polyester resin that forms an ink receiving layer containing a vinyl chloride copolymer or a polyester resin having a functional group is ethyl cellosolve (2-ethoxy). Ethanol), butyl cellosolve (2-n-butoxyethanol), ethyl alcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol, methyl ethyl ketone, isobutyl ketone, ethyl acetate, butyl acetate, isopropyl acetate, dioxane, cyclohexanone, and the like. The organic solvent is not limited to one type when used, and two or more types can be mixed and used.

  In addition, as described above, the mixing ratio of the organic solvent and water when used as a mixed aqueous solution of the organic solvent and water is not particularly limited, and it is easy to adjust the thickness of the ink receiving layer, and the ink receiving layer is thin. It is preferable to determine in consideration of such factors.

  The copolymer or polyester resin forming the ink receiving layer is required to be used as an organic solvent solution or an aqueous solution as described above, and the solid content concentration at that time is 20 to 60% by mass. It is preferable to set it as the range. This is because if it is less than 20% by mass, several times of recoating are required to obtain a desired dry film thickness, and man-hours are required. On the other hand, if it exceeds 60% by mass, uniform coating becomes difficult.

[1-2] Method for forming ink receiving layer:
The agent for forming an ink receiving layer containing a vinyl chloride copolymer or a polyester-based resin having a functional group is applied to one side of a single-layer sheet or a multilayer sheet described later by a known coating method. Thus, an ink receiving layer can be formed. For example, a method of preparing an ink receiving layer by preparing a coating solution dissolved or dispersed in a solvent or water and applying and drying the adjusted coating solution by a known method such as gravure coating. Can do.

  The drying temperature after coating is determined according to the heat resistance of the substrate sheet used and the type of solvent (organic solvent or water) of the copolymer or polyester resin forming the ink receiving layer, but is generally 60 ° C. ~ 120 ° C is preferred. Moreover, considering the damage due to the drying temperature of the base sheet, the drying time is preferably a relatively low temperature and a long drying time, but considering industrial production, it is usually several tens of seconds to several tens of minutes. From less than 1 minute to several minutes is preferable from the viewpoint of productivity. By performing drying under such drying conditions, the ink receiving layer can be formed in tight contact with the substrate sheet. On the other hand, if the drying temperature after application is less than 60 ° C., there is a problem in the drying property of the organic solvent or water of the copolymer or polyester resin forming the ink receiving layer, and the organic solvent or water remains in the ink receiving layer. For this reason, the ink-receiving layer becomes sticky, or the cohesive force of the ink-receiving layer is greatly reduced, so that the function as the ink-receiving layer is greatly reduced, which is not suitable for practical use. On the other hand, if the drying temperature after coating exceeds 120 ° C., the organic solvent and water in the ink receiving layer will evaporate violently, which may cause voids and cracks in the dried ink receiving layer, It is not preferable because the sheet is softened to cause vertical streaks in the base sheet. The drying time depends on the drying temperature, but by setting the desired drying time as described above, a strong ink receiving layer without stickiness can be formed on the base sheet. On the other hand, if the drying time is too short, it is necessary to raise the drying temperature more than necessary, which may cause voids and cracks in the dried ink-receiving layer, and may cause softening of the base sheet. This causes undesirable vertical streaks.

[1-3] Specific mode of ink receiving layer:
For example, as shown in FIG. 1, a transparent laser marking sheet 1 (1A) having an ink receiving layer may be mentioned. In the transparent laser marking sheet 1 (1A) shown in FIG. 1, the base sheet 2 is composed of a single-layer sheet described later, and an ink receiving layer 3 is formed on one side thereof.

  Further, for example, as shown in FIG. 2, a transparent laser marking sheet 1 (1B) on which an ink receiving layer 3 is formed can be mentioned. In the transparent laser marking sheet 1 (1B) shown in FIG. 2, the base material is composed of a multilayer sheet described later, and the ink receiving layer 3 is formed on one side thereof.

[2] Configuration of substrate sheet:
The transparent laser marking sheet of the present invention comprises a transparent polycarbonate resin composition containing 0.0005 to 1 part by mass of a laser light energy absorber with respect to 100 parts by mass of a transparent resin mainly composed of a polycarbonate resin, and has a thickness of 50. ~ 200 μm, a single layer sheet having a total light transmittance of 70% or more, or a skin layer and a core layer, and is formed from at least three layers coextruded by melt coextrusion, and the skin layer Is a transparent resin layer mainly composed of an amorphous aromatic polyester resin, and the core layer has a laser light energy absorber of 0.0005 to 100 parts by mass of the transparent resin mainly composed of a polycarbonate resin. It is a transparent polycarbonate resin composition layer containing 1 part by mass, with a total sheet thickness of 50 to 200 μm and a total thickness of the core layer. On the other hand, it is composed of a multilayer sheet having a thickness ratio of 20 to 80% and a total light transmittance of 70% or more.

[2-1] Single layer sheet:
The single layer sheet is formed from a transparent resin layer mainly composed of a transparent polycarbonate resin. Here, the polycarbonate resin is not particularly limited, but those having a melt volume rate measured according to ISO 1133 of 4 to ³⁰ cm 3/10 minutes can be preferably used. The melt volume rate of less than 4 cm ^3/10 min, although in terms of toughness of the sheet is improved mean is, since the molding processability by melt extrusion is inferior, unfavorably a difficulty in practical use. Further, the melt volume rate is more than 30 cm ^3/10 min, because the poor toughness of the sheet, which is not preferable. As described above, the single layer sheet can be formed from a transparent resin layer containing a polycarbonate resin, thereby obtaining excellent marking properties by irradiation with laser light energy, and further having excellent heat resistance and toughness due to the polycarbonate resin.

  It is important that the base sheet has high transparency. Specifically, when configured as a single-layer sheet, there is no particular limitation on adding and blending resin, filler, etc. within a range that does not impair the transparency of the polycarbonate resin. For the purpose of improving, a blend of a general-purpose polycarbonate resin and a special polycarbonate resin, a blend of a polycarbonate resin and a polyarylate resin, or the like can be employed.

  Examples of the special polycarbonate resin include a siloxane copolymer polycarbonate (product names “Tarlon Neo”, “RC1900” manufactured by Idemitsu Kosan Co., Ltd.), and the blend ratio in this case is 20 to 80% ( Mass basis) is preferred. The blend ratio in the case of blending with a polyarylate resin is also preferably in the same range as described above. Further, for example, a graft polymer having a main chain made of a polycarbonate resin and having a polystyrene resin or a modified acrylonitrile-styrene copolymer resin in the side chain, specifically a product name “Modiper C Series” manufactured by NOF Corporation, etc. Can be mentioned. The blend ratio (mass ratio) in this case is preferably 95/5 to 60/40. Further, the blend ratio in the case of blending with a polyarylate resin is preferably set in the same range as described above.

[2-2] Multilayer sheet:
The multilayer sheet is formed by laminating a plurality of layers having a skin layer and a core layer. That is, in the present embodiment, the base sheet is configured as a multilayer sheet having a “at least three layers” structure including a skin layer and a core layer. However, the “three-layer sheet” means “at least three layers” and is not limited to a three-layer structure. In other words, when the base sheet is composed of multiple layers, the “three-layer sheet” is for convenience of explanation, and the “three-layer sheet” means “a sheet composed of at least three layers”. However, it is not intended to limit the sheet to “three layers”. That is, if it is a structure of 3 layers or more, even if it is formed of 5 layers, 7 layers, or an odd number of layers or more, it is included in the multilayer sheet.

  When the multilayer sheet as the base sheet is composed of the above-described “at least three layers” multilayer structure, the skin layer is disposed on the outermost side of the sheet composed of the multilayer structure, and the core layer. It is arranged on both sides. Furthermore, it is necessary to arrange | position so that a core layer may be pinched | interposed into both skin layers (between). The thickness of the skin layer is not particularly limited, but it is more preferable that the skin layer is formed to have a thickness within a predetermined range described later.

  However, even when the multilayer sheet is composed of the above-mentioned “odd number of more layers”, if the layer structure is excessively large, the layer thickness per layer of the skin layer and the core layer constituting the multilayer is It becomes too thin. Therefore, there is a possibility that a mold stick may be generated in the heat pressing process at the time of lamination. Therefore, the multilayer sheet is preferably composed of 5 layers, more preferably 3 layers.

  That is, the multilayer sheet in this embodiment is composed of odd layers as described above, even if the layer structure is a multilayer sheet composed of even layers, the skin layer or the core layer is composed of two or more of the same or different layers. This is because even if there are a plurality of layers, the plurality of layers are each formed as a single layer, and as a result, the configuration is always the same as that of a multilayer sheet composed of odd layers. Specifically, for example, a base sheet composed of four layers has a layer structure such as skin layer / core layer / core layer / skin layer, and has the same structure as a multilayer sheet composed of odd layers. . That is, in this case, a core layer (core layer / core layer) composed of two layers of the same type or different types is defined as one layer.

  For example, taking a multilayer sheet composed of three layers (so-called “three-layer sheet”) as an example, the outermost layer of one and the other is arranged so that a layer arrangement of skin layer / core layer / skin layer is formed. Two skin layers are arranged. Then, a single core layer is arranged so as to be sandwiched between the two skin layers to form a multilayer sheet. In the case of a multi-layer sheet composed of five layers, one and the other are arranged so that the core layer and the skin layer are arranged in the order of skin layer / core layer / skin layer / core layer / skin layer. Two skin layers are arranged on the outermost sides of the two. Thus, a multilayer sheet as a base sheet may be formed by alternately arranging skin layers and core layers.

  Here, the skin layer is compared with a single-layer sheet made of a transparent resin mainly composed of a transparent polycarbonate resin, which is a resin constituting the core layer, by configuring the base sheet as a multilayer sheet having a multilayer structure. Chemical resistance and scratch resistance can be improved by constituting with an amorphous aromatic polyester resin. Furthermore, when it is desired to form surface irregularity (tactile property) by laser color development, the amorphous aromatic polyester resin that constitutes the skin layer swells by irradiating laser light energy at a higher output than usual, resulting in a tactile property. Can be demonstrated. Laser marking does not necessarily require only smooth marking, but sometimes there is a demand for tactile marking. The single-layer sheet made of a transparent resin mainly composed of the above-mentioned transparent polycarbonate resin has a higher output than usual and laser light energy. Although a clear tactile marking cannot be formed even if it is irradiated, smooth laser marking and tactile marking can be adjusted by the irradiation output of laser light energy by using a multilayer sheet.

[2-2-1] Skin layer in multilayer sheet:
When a skin layer is formed in a multilayer sheet, that is, when a multilayer sheet having a “three-layer structure” is used, the skin layer is configured as both outermost layers arranged outside the three-layer sheet. This skin layer is arranged so as to be sandwiched from both end face sides (outside) of the core layer in the multilayer sheet, and plays a role as a surface layer (both outermost layers) of the three-layer sheet.

  Here, the thicknesses of the skin layers are preferably the same. In plastic IC cards and multilayer laminates for electronic passports, it is common to perform laser marking from the front and back. For this reason, the thickness of the skin layers arranged (laminated) in the outermost layer and the outermost layer of the base material sheet as a laminate differs, resulting in a difference in energy reaching the core layer by laser light energy irradiation. If the thickness of the skin layer is different due to the difference in marking density and the difference in refractive index between the resin constituting the skin layer and the core layer, the visibility of characters / images marked on the core layer is not preferable. For example, when the base sheet is formed as a multilayer sheet from three layers such as skin layer / core layer / skin layer, and the thickness of the core layer is 20% to 80%, the skin layer is on both sides. It is less than 80% and exceeds 20%, and has the laser marking properties, heat resistance, and toughness properties that the core layer resin has, and the chemical resistance, scratch resistance, and heat fusion properties that the skin layer resin has. Excellent characteristics with all of these. However, when the thickness of the core layer is less than 20% and more than 80%, the skin layer is more than 80% and less than 20% on both sides, and when the thickness on both sides of the skin layer is more than 80%, the core layer thickness is 20%. This is not preferable because the laser marking property is inferior as described above. On the other hand, if the thickness is less than 20% on both sides of the skin layer, the thickness on one side is less than 10%, and the thickness of the skin layer becomes too thin at the time of melt-extrusion sheet forming, making it difficult to control the thickness of the skin layer.

[2-2-2] Material of skin layer of multilayer sheet:
Here, the material for forming the skin layer of the multilayer sheet is formed from a resin mainly composed of an amorphous aromatic polyester resin, particularly an amorphous aromatic polyester resin obtained by preparing a copolyester resin. .

  As the transparent resin mainly composed of the non-crystalline aromatic polyester-based resin, it is preferable that the non-crystalline aromatic polyester resin having a glass transition temperature of 80 ° C. or higher is the main component. As such a non-crystalline aromatic polyester resin, a non-crystalline aromatic polyester-based resin (trade name “Easter Copolyester GN071” (PETG) Eastman Chemical Co., Ltd.) using 1,4-cyclohexanedimethanol as a copolymer component. And / or non-crystalline aromatic polyester-based resin (trade name “Eastman Tritan Copolyester FX100” (glass transition temperature 110) using 2,2,4,4-tetramethylcyclobutane-1,3-diol. ° C), “Eastman Tritan copy FX200” (glass transition temperature 119 ° C.) (PCT) (both manufactured by Eastman Chemical Co., Ltd.) and the like.

[2-2-3] Core layer in the multilayer sheet:
When the base sheet is a multilayer sheet, the core layer is configured as a so-called core layer disposed in the center of the base sheet. That is, when the base sheet is configured as a multilayer sheet as a three-layer sheet, the core layer is formed as the core layer of the three-layer sheet so as to be sandwiched between two skin layers disposed on the outermost side. ing.

[2-2-4] Material of core layer of multilayer sheet:
That is, the core layer of the multilayer sheet is formed from a transparent resin layer mainly composed of a transparent polycarbonate resin. However, the polycarbonate resin to be used is not particularly limited, but those having a melt volume rate measured according to ISO 1133 of 4 to ³⁰ cm 3/10 minutes can be preferably used. The melt volume rate of less than 4 cm ^3/10 min, although in terms of toughness of the sheet is improved mean is, since the molding processability by melt extrusion is inferior, unfavorably a difficulty in practical use. Further, when the melt volume rate is more than 30 cm ^3/10 min, because the poor toughness of the sheet, which is not preferable. Thus, by forming the multilayer sheet from a transparent resin layer containing a polycarbonate resin, it is possible to achieve black marking having excellent sharpness and color density by laser light energy irradiation, and the heat resistance and toughness of the polycarbonate resin. Also has sex. By providing a skin layer composed of a transparent resin layer mainly composed of an amorphous aromatic polyester resin on both sides of the core layer, the core layer has excellent properties and is also a weak point of the resin forming the core layer. It can improve the chemical resistance, scratch resistance, and interlayer heat fusion property when a heated laminate with another sheet is formed.

[2-2-5] Core layer thickness:
Here, the thickness of the core layer of the multilayer sheet needs to be formed so that the ratio of the thickness in the entire sheet is 20% to 80%. When the thickness of the core layer is 20% to 80%, the skin layer is less than 80% and more than 20% on both sides, and the laser marking properties, heat resistance, and toughness that are the characteristics of the resin forming the core layer And exhibits excellent properties that combine all of the chemical resistance, scratch resistance, and heat-fusibility properties that the skin layer resin has. However, when the thickness of the core layer is less than 20% and more than 80%, the skin layer is more than 80% and less than 20% on both sides, and when the skin layer is more than 80% on both sides, the core layer thickness is 20%. This is not preferable because the laser marking property is inferior as described above. Further, if the skin layer is less than 20% on both sides, the thickness on one side is less than 10%, and the thickness of the skin layer becomes too thin at the time of melt-extrusion sheet forming, making it difficult to control the thickness of the skin layer.

[2-3] Base sheet thickness:
Moreover, the thickness of a base material sheet is 50-200 micrometers in both a single layer sheet and a multilayer sheet. When the total thickness of the base sheet is less than 50 μm, a laser beam energy is applied to a card laminate (hereinafter sometimes simply referred to as a card) using such a base sheet as an oversheet. When characters and images are formed by black marking, the black / white contrast with the core sheet (white or printed) that is the base layer of the transparent laser marking sheet marked with black is insufficient. Since visibility is inferior, it is not preferable. On the other hand, if the total thickness of the transparent laser marking sheet exceeds 200 μm, the total thickness of the plastic IC card greatly exceeds the thickness specified by ISO around 760 μm, which is not practical. For example, in a non-contact type plastic IC card, 5 of transparent laser marking sheet / core sheet (white printing) / inlet sheet (sheet provided with IC chip + antenna) / core sheet (white printing) / transparent laser marking sheet. Taking a laminated body as an example, generally, the inlet sheet is 300 to 400 μm, and the core sheet (white printing) is 100 in order to prevent the IC chip + antenna arranged on the inlet sheet from being seen (hiding property) 100 In many cases, when the total thickness of the transparent laser marking sheet exceeds 200 μm, the total thickness of the multilayer laminate greatly exceeds about 760 μm.

  In this way, when the base sheet is a single layer sheet or a multilayer sheet, by setting the total thickness of the sheet and the thickness ratio of the core layer of the multilayer sheet to a desired range, only the laser marking property of the transparent laser marking sheet can be obtained. In other words, it is possible to achieve both excellent properties such as heat resistance, scratch resistance, chemical resistance, and heat-fusibility.

[3] Laser energy absorber:
It is essential to blend a laser beam energy absorber in the base sheet. With such a configuration, the laser coloring property when laser marking is performed is excellent, the contrast between the background portion and the printed portion is increased, and a clear character, symbol, or image can be obtained. Furthermore, when a base material sheet is comprised as a single layer sheet, it contains 0.0005-1 mass part of laser beam energy absorbers with respect to 100 mass parts of transparent resin which has polycarbonate resin as a main component. In the case of a polycarbonate resin composition and the base sheet is a multilayer sheet, the core layer has a laser light energy absorber of 0.0005 with respect to 100 parts by mass of the transparent resin mainly composed of the polycarbonate resin. A polycarbonate resin composition containing ˜1 part by mass. A laser capable of forming clear characters, symbols, or images with excellent contrast with the underlying core sheet (background) by irradiating laser light energy to single layer sheets and multilayer sheets using such a polycarbonate resin composition. Marking can be obtained.

  The above laser light energy absorber is not particularly limited as long as it can absorb laser light energy and change the color, tone, and lightness different from the background color. For example, carbon black, titanium black, metal Examples thereof include at least one selected from the group consisting of oxides, metal sulfides, metal nitrides, metal soot oxides, and metal carbonates. More preferable laser light energy absorbers are at least one selected from carbon black, titanium black, and metal oxide, or two or more.

  Here, the average particle diameter of carbon black, titanium black, metal oxide, metal sulfide, metal nitride, metal soot oxide, and metal carbonate as the laser light energy absorber is preferably less than 150 nm. More preferably, it is less than 100 nm. Further, carbon black having an average particle diameter of 10 to 90 nm and dibutyl phthalate (DBT) oil absorption of 60 to 170 ml / 100 gr, or a combination of the carbon black and titanium black having an average particle diameter of less than 150 nm, or a metal oxide is preferable. . If the average particle size of carbon black, titanium black, metal oxide, metal sulfide, or metal nitride exceeds 150 nm, the transparency of the sheet may be reduced, or large irregularities may be generated on the sheet surface, which is not preferable. . Further, if the average particle size of the carbon black is less than 10 nm, the laser color developability deteriorates and it is too fine to be difficult to handle. Further, when the DBT oil absorption is less than 60 ml / 100 gr, the dispersibility is poor, and when it exceeds 170 ml / 100 gr, the concealability is poor, which is not preferable.

  As metal oxides that are laser light energy absorbers, zinc, magnesium, aluminum, iron, titanium, silicon, antimony, tin, lead, copper, manganese, cobalt, vanadium, bismuth, niobium can be used as the metal that forms the oxide. , Molybdenum, ruthenium, tungsten, palladium, silver, platinum and the like. Furthermore, ITO, ATO, AZO, etc. are mentioned as a composite metal oxide.

  Examples of metal sulfides that are laser light energy absorbers include zinc sulfide and cadmium sulfide. Further, examples of the metal nitride include titanium nitride. Examples of metal oxalates include magnesium oxalate and copper oxalate. Furthermore, basic metal carbonate can be mentioned as a metal carbonate.

  Thus, as the laser light energy absorber, carbon black, metal oxide, and composite metal oxide are preferably used, and each is used alone or in combination.

  In addition, in the case of carbon black, the addition amount (blending amount) of the laser light energy absorber needs to be added (blending) 0.0005 to 1 part by mass, and most preferably 0.0008 to 0.1 mass. Part. Further, when carbon black and at least one selected from metal oxides, metal sulfides, and metal nitrides having an average particle diameter of less than 150 nm are used in combination, the blending amount of the mixture is 0.0005 to 1 part by mass Most preferably, the amount is 0.0008 to 0.5 parts by mass.

  Thus, the addition amount (blending amount) of the laser light energy absorber is adjusted to a desired amount because the transparent laser marking sheet is preferably transparent. In other words, when used for laminated sheets (data pages) for plastic IC cards and electronic passports, usually white sheets or white sheets that are printed on one side of a white sheet by offset printing or the like as the underlayer of a transparent laser marking sheet (Printing core sheet) is heated and laminated. For example, in a plastic IC card, for example, five layers of transparent laser marking sheet / printing core sheet / inlet (sheet) / printing core sheet / transparent laser marking sheet are laminated and heated using a vacuum press or the like. A laminate (card-like laminate) is produced. If this card-like laminate is punched with a punching machine to produce a plastic IC card, images, characters and symbols are formed by black marking on the transparent laser marking sheet layer by irradiating laser light energy from the outermost surface of the card. To do. In this case, the transparent laser marking sheet layer has a thickness of 50 to 200 μm, but when the transparent laser marking sheet layer is a single layer, it is easily marked by black marking with the entire thickness, and images and characters, The symbol cannot be deleted. It is very difficult for a counterfeiter who tries to counterfeit because the entire transparent laser marking sheet layer must be scraped in order to delete it. Therefore, laser marking is extremely effective in preventing forgery and tampering. In this way, when used in combination with a transparent laser marking sheet / printing core sheet (a lot of light-colored printing on a white sheet), the white color of the underlayer and the black image laser-marked on the transparent laser marking sheet By virtue of the black / white contrast with characters and symbols, clear images, characters and symbols can be visually recognized. In addition, since the laser marking sheet is transparent, the parts that are not marked with black markings are transparent, so that the printing of the underlayer looks beautiful. The information printed on the underlayer (fixed information) and the transparent laser marking sheet Both of the information (variation information, personal information in the case of individuals) with black markings on the layer are clearly visible, and a plastic IC card with high security can be obtained.

  When the average particle diameter of the above laser light energy absorber exceeds 150 nm, the transparency of the transparent laser marking sheet is lowered, which is not preferable. Further, if the blending amount of these laser light energy absorbers exceeds 1 part by mass, the transparency is lowered. In addition, the amount of absorbed energy becomes too large, causing the resin to deteriorate. As a result, sufficient contrast cannot be obtained. On the other hand, if the addition amount of the laser beam energy absorber is less than 0.0005 parts by mass, a sufficient contrast cannot be obtained, which is not preferable.

[4] Lubricant, antioxidant, anti-coloring agent, ultraviolet absorber, and light stabilizer:
Moreover, in this embodiment, it is preferable to make a transparent laser marking sheet contain a lubricant, and when a transparent laser marking sheet consists of a multilayer sheet, it is preferable to make a skin layer contain a lubricant. This is because inclusion of a lubricant can prevent fusion to the press plate during molding and heating.

  Examples of the lubricant include fatty acid esters, fatty acid amides, and fatty acid metal salts, and it is preferable to add at least one lubricant selected from them.

  Examples of fatty acid ester lubricants include butyl stearate, cetyl palmitate, stearic acid monoglyceride, stearic acid diglyceride, stearic acid triglyceride, ester of montan wax acid, wax ester, dicarboxylic acid ester, complex ester, fatty acid amide type Examples of the lubricant include stearic acid amide and ethylene bisstearyl amide. Examples of the fatty acid metal salt lubricant include calcium stearate, magnesium stearate, zinc stearate, aluminum stearate and barium stearate.

  Furthermore, in this embodiment, when the base sheet of the transparent laser marking sheet is configured as a single layer sheet, if necessary, at least one of an antioxidant and an anti-coloring agent, and ultraviolet absorption. It is also preferable to contain at least one of an agent and a light stabilizer. In addition, when the base sheet of the transparent laser marking sheet is configured as a multilayer sheet, the skin layer is optionally provided with at least one of an antioxidant and an anti-coloring agent, and an ultraviolet absorber and a light stabilizer. It is also preferable to contain at least one agent. Addition (mixing) of at least one of an antioxidant and an anti-coloring agent effectively acts on physical property reduction and hue stabilization due to molecular weight reduction during molding processing. Here, a phenolic antioxidant or a phosphite ester colorant is used as at least one of the antioxidant and the colorant. In addition, the addition (formulation) of at least one of an ultraviolet absorber and a light stabilizer suppresses the light deterioration resistance during storage of the transparent laser marking sheet and the actual use of electronic passports and plastic cards as final products. It works effectively. As such an ultraviolet absorber, a benzotriazole compound, a hydroxyphenyltriazine compound, a cyclic imino ester compound, or the like can be used.

  As said antioxidant, a phenolic antioxidant, an amine antioxidant, etc. can be used, for example.

  Examples of the phenol-based antioxidant include α-tocopherol, butylhydroxytoluene, sinapyl alcohol, vitamin E, n-octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 3 -5-di-t-butyl-4-hydroxytoluene; pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- ( 3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2- t-butyl-6- (3′-t-butyl-5′-methyl-2′-hydroxybenzyl) -4-methylphenol Acrylate, 2,6-di-tert-butyl-4- (N, N-dimethylaminomethyl) phenol, 3,5-di-tert-butyl-4-hydroxybenzylphosphonate diethyl ester, 2,2′-methylenebis (4-methyl-6-tert-butylphenol), 2,2′-methylenebis (4-ethyl-6-tert-butylphenol), 4,4′-methylenebis (2,6-di-tert-butylphenol), 2, 2′-methylenebis (4-methyl-6-cyclohexylphenol), 2,2′-dimethylene-bis (6-α-methyl-benzyl-4-cresol), 2,2′-ethylidene-bis (4,6- Di-t-butylphenol), 2,2'-butylidene-bis (4-methyl-6-t-butylphenol), 4,4'-butylidenebis (3-methyl-6-) -Butylphenol), triethylene glycol-N-bis-3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate, 1,6-hexanediol bis [3- (3,5-di- t-butyl-4-hydroxyphenyl) propionate], bis [2-t-butyl-4-methyl 6- (3-t-butyl-5-methyl-2-hydroxybenzyl) phenyl] terephthalate, 3,9-bis {2- [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1,1, -dimethylethyl} -2,4,8,10-tetraoxaspiro [5,5 ] Undecane, 4,4'-thiobis (6-t-butyl-m-cresol), 4,4'-thiobis (3-methyl-6-t-butylphenol), 2,2'-thiobi (4-methyl-6-tert-butylphenol), bis (3,5-di-tert-butyl-4-hydroxybenzyl) sulfide, 4,4′-di-thiobis (2,6-di-tert-butylphenol) 4,4′-tri-thiobis (2,6-di-t-butylphenol), 2,2-thiodiethylenebis- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] 2,4-bis (n-octylthio) -6- (4-hydroxy-3 ′, 5′-di-t-butylanilino) -1,3,5-triazine, N, N′-hexamethylenebis- ( 3,5-di-t-butyl-4-hydroxyhydrocinnamide), N, N′-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine, 1,1 , 3-Tris (2-methyl -4-hydroxy-5-t-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tris (3 , 5-di-t-butyl-4-hydroxyphenyl) isocyanurate, tris (3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate, 1,3,5-tris (3,5-di) -T-butyl-4-hydroxybenzyl) isocyanurate, 1,3,5-tris (4-t-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanurate, 1,3,5-tris 2 [ 3 (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] ethyl isocyanurate and tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) Propionyloxymethyl] methane, and the like.

  Among these examples, n-octadecyl-3- (3,5-di-t-butyl-hydroxyphenyl) propionate, 1,3,5-trimethyl-2,4,6-tris (3, 5-di-t-butyl-4-hydroxybenzyl) benzene, 1,3,5-tris (3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate, tetrakis [3- (3,5- Di-t-butyl-4-hydroxyphenyl) propionyloxymethyl] methane is preferred, and n-octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate is particularly preferred. The said hindered phenolic antioxidant can be used individually or in combination of 2 or more types.

  Examples of coloring inhibitors include phosphite compounds, such as triphenyl phosphite, tris (nonylphenyl) phosphite, tridecyl phosphite, trioctyl phosphite, trioctadecyl phosphite, didecyl. Monophenyl phosphite, dioctyl monophenyl phosphite, diisopropyl monophenyl phosphite, monobutyl diphenyl phosphite, monodecyl diphenyl phosphite, monooctyl diphenyl phosphite, 2,2-methylenebis (4,6-di-t-butyl Phenyl) octyl phosphite, tris (diethylphenyl) phosphite, tris (di-iso-propylphenyl) phosphite, tris (di-n-butylphenyl) phosphite, tris (2,4-di t-butylphenyl) phosphite, tris (2,6-di-t-butylphenyl) phosphite, distearyl pentaerythritol diphosphite, bis (2,4-di-t-butylphenyl) pentaerythritol diphosphite Bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite, bis (2,6-di-t-butyl-4-ethylphenyl) pentaerythritol diphosphite, phenylbisphenol A Examples thereof include pentaerythritol diphosphite, bis (nonylphenyl) pentaerythritol diphosphite, and dicyclohexyl pentaerythritol diphosphite.

  Furthermore, as another phosphite compound in the coloring inhibitor, those having a cyclic structure by reacting with dihydric phenols can be used. For example, 2,2′-methylenebis (4,6-di-t-butylphenyl) (2,4-di-t-butylphenyl) phosphite, 2,2′-methylenebis (4,6-di-t- Butylphenyl) (2-t-butyl-4-methylphenyl) phosphite, 2,2′-methylenebis (4-methyl-6-t-butylphenyl) (2-t-butyl-4-methylphenyl) phosphite And 2,2′-ethylidenebis (4-methyl-6-t-butylphenyl) (2-t-butyl-4-methylphenyl) phosphite.

  Among the anti-coloring agents described above, tris (2,4-di-t-butylphenyl) phosphite is particularly preferable because of its extremely high purity and excellent hydrolysis resistance and volatilization resistance. The phosphite ester coloration inhibitor may be used alone or in combination of two or more. Moreover, you may use together with a phenolic antioxidant.

  Specific examples of the above-described ultraviolet absorbers, which are benzotriazole compounds, hydroxyphenyltriazine compounds, and cyclic imino ester compounds, are as follows.

  Examples of the benzotriazole ultraviolet absorber include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole and 2- (2′-hydroxy-3 ′, 5′-di-t-amylphenyl) benzotriazole. 2- (2′-hydroxy-3 ′, 5′-bis (α, α′-dimethylbenzyl) phenylbenzotriazole, 2,2′methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol], methyl-3- [3-t-butyl-5- (2H-benzotriazol-2-yl) -4-hydroxyphenylpropionate-polyethylene glycol The compound represented by the condensate of these can be mentioned.

  Examples of the hydroxyphenyl triazine-based compound ultraviolet absorber include 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5-hexyloxyphenol and 2- (4,6-bis). And (2,4-dimethylphenyl) -1,3,5-triazin-2-yl) -5-hexyloxyphenol.

  Furthermore, as the cyclic imino ester compound ultraviolet absorber, for example, 2,2′-p-phenylenebis (3,1-benzoxazin-4-one), 2,2′-2-phenylenebis (3,1- And benzoxazin-4-one) and 2,2′-4,4′-diphenylenebis (3,1-benzoxazin-4-one).

  Examples of the light stabilizer include bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, tetrakis (2 , 2,6,6-tetramethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate, tetrakis (1,2,2,6,6-pentamethyl-4-piperidyl) -1,2 , 3,4-Butanetetracarboxylate, poly {[6- (1,1,3,3-tetramethylbutyl) amino-1,3,5-triazine-2,4-diyl] [(2,2, 6,6-tetramethylpiperidyl) imino] hexamethylene [(2,2,6,6-tetramethylpiperidyl) imino]} and polymethylpropyl 3-oxy- [4- (2,2,6,6-tetra Methyl) piperi Hindered amine compounds typified by [nyl] siloxane can also be used, and such a light stabilizer can be used in combination with the above-mentioned ultraviolet absorber or various antioxidants in some cases in terms of weather resistance, etc. Demonstrate.

  More preferably, if the base sheet is a single-layer sheet, the transparent laser marking sheet comprises a transparent polycarbonate resin comprising 0.01 to 3 parts by mass of a lubricant with respect to 100 parts by mass of the transparent resin mainly composed of a polycarbonate resin. Further, the transparent laser marking sheet comprises 0.1 to 5 parts by mass of at least one of an antioxidant and an anti-coloring agent with respect to 100 parts by mass of the transparent resin having a polycarbonate resin as a main component. 0.1-5 mass parts of at least 1 sort (s) of an absorber and a light stabilizer are included.

  Furthermore, if the base sheet is a multi-layer sheet (so-called three-layer sheet), the skin layer of the multi-layer sheet has a lubricant of 0.01 to 100 parts by mass with respect to 100 parts by mass of the transparent resin mainly composed of an amorphous aromatic polyester resin. 3 parts by mass of a transparent polycarbonate resin composition, and further, at least one of the skin layer of the multilayer sheet and the core layer is an antioxidant with respect to 100 parts by mass of the transparent resin mainly composed of the polycarbonate resin. And 0.1 to 5 parts by mass of at least one kind of coloring inhibitor and 0.1 to 5 parts by mass of at least one kind of ultraviolet absorber and light stabilizer.

  Here, the addition amount of the lubricant is 0.01 to 3 parts by mass, preferably 0.05 to 1.5 parts by mass. If it is less than 0.01 parts by mass, it will be fused to the press plate at the time of hot pressing, and if it exceeds 3 parts by mass, there will be a problem in interlayer heat fusion at the time of multi-layer heating press of electronic passports and cards. Further, when the addition amount of at least one of the antioxidant and the coloring inhibitor is less than 0.1 parts by mass, the thermal oxidation reaction of the polycarbonate resin in the step of melting, extruding and molding, and the thermal discoloration resulting therefrom Problems are likely to occur. On the other hand, if it exceeds 5 parts by mass, problems such as bleeding of these additives are likely to occur. Furthermore, when the addition amount of at least one of the ultraviolet absorber and the light stabilizer is less than 0.1 parts by mass, the effect is poor, and light defects such as deterioration due to light resistance and associated discoloration tend to occur. Furthermore, if it exceeds 5 parts by mass, problems such as bleeding of these additives are likely to occur, which is not preferable.

  It should be noted that the fusion and concealment properties of the multilayer sheet and the contrast with the laser marking portion are extremely important factors such as whether the multilayer sheet can be practically used, productivity, market needs, etc.

[5] Substrate sheet forming method:
In the present invention, in order to obtain a base sheet, for example, in the case of a single layer sheet, a method of melt extrusion molding a resin composition can be employed. Also, in the case of a multilayer sheet, a method of melt extrusion molding the resin composition constituting each layer, a method of forming a film of what constitutes each layer, a method of laminating this, and a melt extrusion of the two layers, Although there is a method of laminating a separately formed film, etc., it is preferable to laminate and integrate by melt extrusion from the viewpoint of production and cost.

  Specifically, in the case of a multi-layer sheet, each resin composition constituting each layer is blended, or pelletized as necessary, and charged into each hopper of a three-layer T-die extruder with T-die jointly connected. To do. And it melts at the temperature of 200-300 degreeC, 3 layer T-die melt-extrusion molding is carried out, and it cools and solidifies with a cooling roll etc., and can form a 3 layer laminated body. In addition, the transparent laser marking sheet and colored multilayer sheet of this invention are not limited to the said method, It can form by a well-known method. For example, it can be obtained according to the description of JP-A-10-71763, pages (6) to (7).

[6] Total light transmittance:
Furthermore, it is necessary that the total light transmittance of the transparent laser marking sheet is 70% or more. More preferred is 85% or more. For example, when the transparent laser marking sheet of the present invention is used for a laminated sheet for a plastic IC card or an electronic passport, printing is generally performed for those uses. Therefore, for example, a white sheet (printing core sheet) on which characters, figures, and the like have been printed (hereinafter, a white sheet on which characters, figures, etc. have been printed, is appropriately printed on the lower part of the transparent laser marking sheet of the present embodiment. Laminating a transparent laser marking sheet, which is the outermost layer, by irradiating it with laser light energy, producing a black color, marking images and characters, and designing and laser marking in the printing section Often used in combination with anti-counterfeiting. By combining in this way, since the underlayer is white, a clear image can be obtained by vividness of the printed portion and black / background color contrast of the laser marking portion. That is, when laminating white sheets or the like, these effects can be maximized by setting the transparency of the outermost layer to the above-mentioned desired range of total light transmittance (clearness of black / white contrast). Sex can stand out.) In other words, the transparency of the outermost layer is important for ensuring the sharpness of the printed portion and the black / white contrast of the laser marking portion, and the black / white contrast is less than 70% of the total light transmittance. Is insufficient, and there is a problem that sufficient marking properties cannot be secured, and since printing is performed on the base white sheet, this causes a problem in the visibility of the printing.

  Further, in the present invention, since the ink receiving layer is provided on the transparent laser marking sheet, for example, when an example of a plastic IC card is given, a transparent laser marking sheet / white core sheet / inlet / white having an ink receiving layer is provided. After laminating 5 sheets of transparent laser marking sheet with a core sheet / ink-receiving layer and heating and laminating them with a vacuum press machine, etc., punching out to make a card, and then using a direct thermal transfer printing machine After color printing of images, letters, symbols, etc., usually a protective coating is applied, but then, by marking the images, letters, symbols, etc. in black by irradiating laser light energy to areas that are not color printed, The image and black marking can be used together, and the printed color image can be scraped off. Since images and characters, symbols and the like remain by black markings as was very excellent in anti-counterfeiting properties. In other words, a plastic IC card with high security can be obtained.

  As another example, a transparent laser marking sheet provided with an ink receiving layer / printing core sheet / inlet / printing core sheet / a transparent laser marking sheet provided with an ink receiving layer is stacked and vacuum pressed. After heating and laminating with a machine, etc., punching out to produce a card, directly printing an image (for example, a person image) on the card using a thermal transfer printing machine, usually a protective coating, then color printing By irradiating laser light energy to the unmarked part and marking the images, characters, symbols, etc. in black, the background image (fixed information) of the printed core sheet and the image by direct thermal transfer color printing (in the case of personal images, individual Information) and fluctuation information by black marking (personal information in the case of personal images, characters and symbols) can be used together. Variable information such as the information can be formed on demand, it is possible to obtain a high plastic IC card to the same security.

  Here, the “total light transmittance” is an index indicating the ratio of light transmitted through the light incident on the sheet, film, film, etc., and the total light transmittance when all the incident light is transmitted is 100%. In this specification, “total light transmittance” indicates a value measured in accordance with JIS K7105 (light transmittance and total light reflectance). Measurement of this total light transmittance Can be measured using, for example, a Nippon Denshoku Industries haze meter (trade name: “NDH 2000”), a spectrophotometer (trade name “EYE7000” manufactured by Macbeth Co., Ltd.), and the like.

[7] Plastic card:
Next, a plastic card using the transparent laser marking sheet described so far will be described. However, this is an example and is not limited.

  First, an embodiment of a plastic card is shown in FIG. That is, the plastic card 14 is made of transparent laser marking sheet 1 (1A, 1B) (oversheet) / core sheet 6 / inlet sheet 7 / core sheet 6 / transparent laser marking sheet 1 (1A, 1B) (oversheet). It has the structure which laminates | stacks a layer. In addition, there is a configuration in which three layers of transparent laser marking sheet 1 (1A) / core sheet 6 / transparent laser marking sheet 1 (1A) that do not use the inlet sheet 7 are laminated.

  The above-mentioned plastic card is formed by heating and laminating the five sheets as described above, and then punching out to produce a blank card. Thereafter, direct thermal transfer color printing for the card is performed, and further, laser light energy is irradiated to produce a color card. A plastic card with printing and laser marking can be obtained.

  Here, direct thermal transfer color printing is performed by pressing a sublimation ink ribbon (dye system) against a blank card and heating it to transfer the sublimation ink onto the card surface, and then applying a protective transparent coating. Normally, these processes can be performed by a single machine system. On the other hand, indirect thermal transfer color printing, a sublimation ink ribbon (pigment system) is transferred to a PET film according to the same principle as described above, and then the PET film on which the sublimation ink is transferred is attached to a blank card or sublimation type. The PET film on which the ink has been transferred is pressed against a blank card and heated to transfer the sublimation ink onto the card surface, and then a protective transparent coating is applied.

  The direct thermal transfer color printing described above is a dye-based ink that has a clear and clean color, and only the ribbon of the ink ribbon is discarded. In contrast, indirect thermal transfer color printing is a pigment-based ink, so that the color development is not very clear, and in the method of pasting to a blank card for each PET film to which sublimation ink is transferred, the PET film is at least about 20 μm. Since it has a thickness, when the marking increases by irradiating laser light energy on the PET film, it is inferior in the density and sharpness of the obtained marking, and in some cases between the PET film and the card surface. There is a problem that laser marking causes blistering and the marked characters / images are blurred and cannot be seen well. Further, in the latter printing method in indirect thermal transfer color printing, the PET film that has been transferred once is discarded, which is not environmentally preferable. Further, the process is considerably complicated and there is a problem in productivity. In the present invention, it is more preferable to perform color printing by sublimation type direct thermal transfer method among color printing by sublimation type direct thermal transfer method or sublimation type indirect thermal transfer method.

  As described above, the transparent laser marking sheet 1 (1A, 1B) is a transparent laser marking sheet in which an ink receiving layer is provided on at least one surface of a transparent substrate sheet. That is, the transparent base sheet is a single layer sheet composed of a polycarbonate resin and a transparent polycarbonate resin composition containing a laser light energy absorber, or a transparent resin layer mainly composed of an amorphous aromatic polyester resin as a skin layer. As a multilayer sheet having the transparent polycarbonate resin composition as a core layer. Further, the ink receiving layer is a transparent laser marking sheet formed from a vinyl chloride copolymer or a polyester-based resin having a functional group and configured as a layer having a dry film thickness of 1 to 20 μm. .

  Further, the core sheet 6 has a single layer sheet made of an amorphous aromatic polyester resin, a single layer sheet made of an alloy polymer of an amorphous aromatic polyester resin and a polycarbonate resin, and further has a skin layer and a core layer. In addition, a multilayer sheet comprising at least three layers by melt extrusion molding, a skin layer made of a copolyester resin having a glass transition temperature of 80 ° C. or higher, and a core layer made of a polycarbonate resin can be used. In the case of a single-layer sheet, these core sheets preferably contain 1 part by mass or more of at least one resin colorant such as a dye or pigment with respect to 100 parts by mass of the resin forming the core sheet. In the case of a multilayer sheet, it is preferable to contain 1 part by mass or more of at least one dye or pigment with respect to 100 parts by mass of the skin layer resin and the core layer resin. Furthermore, it is preferable that the total thickness of the core sheet 6 is 50 to 400 μm, and that the thickness ratio of the core layer to the total thickness of the multilayer sheet is 20% or more and less than 80%.

  In single-layer and multilayer core sheets, skin layers and core layers of single-layer sheets and multilayer sheets contain 1 part by mass or more of at least one resin colorant such as dye or pigment with respect to 100 parts by mass of the forming resin. It is preferable to let it be. This is different from the transparent laser marking sheet. In this way, 1 part by mass or more of the colorant of the resin such as the coloring dye and the pigment is compounded by laminating a plurality of laminated sheets of the transparent laser marking sheet and the colored core sheet 7 as described later. Later, when marking is performed by irradiating with laser light energy, if the laser light energy irradiation part is marked black, the core sheet as the lower layer must be lightly colored from the viewpoint of contrast, especially white is good It is. Furthermore, it is common that an image or the like is fixedly printed on the core sheet by color printing using offset printing or the like, and light color or particularly white is desirable from the viewpoint of printing visibility.

  As coloring agents for resins such as coloring dyes and pigments, titanium oxide, barium oxide, zinc oxide as a white pigment, iron oxide, titanium yellow as a yellow pigment, iron oxide as a red pigment, cobalt blue ultramarine blue as a blue pigment, etc. Is mentioned. However, in order to improve the contrast, a light colored and lightly colored system is preferable.

  Among the coloring dyes and pigments, it is more preferable to add resin colorants such as white dyes and pigments, which stand out in contrast.

  Furthermore, with respect to 100 parts by mass of the resin forming the core sheet, 0.1 to 5 parts by mass of at least one of an antioxidant and an anti-coloring agent, and at least one of an ultraviolet absorber and a light stabilizer are added. It is also one of the preferable forms to contain 0.1-5 mass parts. In the case where at least one of an antioxidant and an anti-coloring agent is added (blended), it effectively acts on physical property reduction and hue stabilization due to molecular weight reduction during molding processing. In addition, when adding (compounding) at least one of an ultraviolet absorber and a light stabilizer, these sheets are used for long-term storage and light during actual use of plastic IC cards and electronic passports as final products. This is effective for suppressing deterioration. That is, with such a configuration, a desired amount of at least one of an antioxidant and an anti-coloring agent and at least one of an ultraviolet absorber and a light stabilizer can be appropriately and selectively contained. In addition, since the region to be contained can be selected as appropriate, the effect of the present invention can be further exhibited synergistically as the entire sheet.

  In addition, the lubricant, antioxidant, coloring inhibitor, etc. of the core sheet 6 are the same as the lubricant, antioxidant, and coloring inhibitor contained in the transparent laser marking sheet. Therefore, please refer to the transparent laser marking sheet.

[8] Data page for electronic passport:
The basic configuration of the electronic passport data page is of the following two types. First, one of them is an IC chip type. As shown in FIG. 4, an oversheet (transparent) 8 / oversheet (transparent laser marking sheet) 1 (1A, 1B) / core sheet (white) 9 / Inlet sheet 7 / hinge sheet 11 / core sheet (white) 9 / over sheet (transparent laser marking sheet) 1 (1A, 1B) / over sheet (transparent) 8 (15 (15A)). Further, as shown in FIG. 5, the other is an IC chipless type, which is an oversheet (transparent) 8 / oversheet (transparent laser marking sheet) 1 (1A, 1B) / core sheet (white) 9 / It is composed of hinge sheet 11 / core sheet (white) 9 / over sheet (transparent laser marking sheet) 1 (1A, 1B) / over sheet (transparent) 8 (15 (15B)). Personal information (images, characters, etc.) is written by irradiating these data pages with laser light energy, and the hinge sheet is used as a cover or other visa sheet by sewing binding using the part that protrudes from other sheets. Electronic passports are bound by binding them firmly together.

  In the above structure, a function for firmly binding personal information, etc., recorded on a storage medium such as an IC chip disposed on a page where data is written and an inlet sheet of the data page to a cover sheet or the like with a hinge sheet, It is important that the heat-fusability between each layer, especially between the core sheet and the hinge sheet, is firmly heat-fused. For these purposes, the hinge sheet plays a very important role in the electronic passport. . Therefore, the performance required for the hinge sheet requires not only flexibility, repeated bending fatigue strength, tear strength, sewing binding strength, but also strong interlayer heat fusion and heat resistance in the heating lamination process. .

[9] Hinge sheet:
The hinge sheet (binding sheet) 11 that plays the role as described above is at least one selected from thermoplastic polyester resins, thermoplastic polyester elastomers, thermoplastic polyamide resins, thermoplastic polyamide elastomers, thermoplastic polyurethane resins, and thermoplastic polyurethane elastomers. Sheets formed from seeds, or integral lamination sheets of these polymers and various woven fabrics, knitted fabrics, and nonwoven fabrics are preferable.

  Further, the hinge sheet 11 is used for easy binding to the electronic passport as described above. Accordingly, the shape, length, etc. are not particularly limited as long as the shape and size are easy to bind, and can be appropriately selected according to need.

  More preferably, the hinge sheet 11 has a thickness of 50 to 500 μm, preferably 50 to 250 μm. If the thickness of the hinge sheet 11 is less than 50 μm, the strength of the sewing binding portion is insufficient, and there is a concern that the multilayer sheet on which personal information such as personal images, characters, numbers, and the like is laser-marked is peeled off from the electronic passport. Further, if the thickness exceeds 500 μm, the total thickness of the data page becomes too large to be practically used, and further, the rigidity of the sheet becomes too large, and the electronic passport is naturally opened even when not in use. .

  Furthermore, it is preferable to form one end of the hinge sheet 11 so as to project from the data page (reference numeral 12 in FIGS. 4 and 5), and it is sufficient that the projecting length is 5 to 100 mm. By forming the overhanging portion 12 on the hinge sheet 11, the overhanging portion 12 can be used to bind the cover sheet or the like to the cover sheet, and then attached to the cover sheet with an adhesive. Reference numeral 13 is a sewing machine binding.

  The dimension of the overhanging portion 12 is 5 to 100 mm, but is preferably 5 to 50 mm, and more preferably 5 to 20 mm.

[10] Method for producing transparent laser marking sheet (oversheet):
In the present invention, when the substrate sheet constituting the transparent laser marking sheet (oversheet) is a single layer, a method for producing a sheet by melt extrusion molding of a resin composition using one T-die extruder In general, when the transparent laser marking sheet (oversheet) is a multilayer sheet having three or more layers, for example, in a three-layer sheet, two extruders are connected to one three-layer T die. A method of producing a three-layer sheet by two-type three-layer coextrusion molding is common.

  After cutting the transparent laser marking sheet, core sheet, and the like obtained as described above into predetermined dimensions, a laminated body of data pages for cards and electronic passports is obtained by heat lamination using a vacuum press machine or the like. Can do. In this lamination, the ink receiving layer provided on the transparent laser marking sheet is disposed so as to be positioned on the outermost layer. By arranging in this way, printing can be performed on the ink receiving layer. Moreover, in another method of the card laminate, it is possible to roll a roll sheet such as a transparent laser marking sheet and a core sheet into a roll sheet shape by using a heating lamination apparatus and then cut to a predetermined card size. is there. The ink-receiving layer of the transparent laser marking sheet is a solvent solution for forming an ink-receiving layer containing a vinyl chloride copolymer or a polyester-based resin having a functional group on one side after melt extrusion of the transparent laser marking sheet. Alternatively, an ink receiving layer is formed by coating (applying) an aqueous solution. It is preferable to mold by heating and pressurizing so that the core sheet is in contact with the side opposite to the side where the ink receiving layer is formed.

  Here, the desired time, the desired pressure, and the desired temperature are not particularly limited, and are preferably selected appropriately in consideration of the apparatus to be used, the composition and type of various sheets, and the like. For example, when a rotary type vacuum press is used, in general, the tact time is about 60 seconds to 3 minutes, the pressure is 1 to 20 Mpa, the press temperature is 120 to 190 ° C., for example, When using a vacuum press of the mold, the working pressure and the press temperature are the same as when using a rotary vacuum press, but the cycle time is about 30 to 90 minutes.

[11] Printing method of fixed information on plastic card and electronic passport data page:
The basic structure of data pages for plastic cards and electronic passports is as described above, and fixed information is printed on one side of the core sheet (white) by color printing, such as offset printing, inkjet printing, silk screen printing, etc. Printing is done. In this way, a plurality of sheets are heated and laminated by the above-described method together with other sheets such as the printed core sheet and oversheet.

  Here, examples of the plastic card to which the transparent laser marking sheet of the present invention can be applied include various ID cards, health insurance cards, transportation cards such as ETC cards, and various IC cards such as bank cards. . However, these are merely examples, and the present invention is not limited to these.

  In a general plastic IC card for laser marking, after performing color printing on one side of the core sheet by offset printing or the like, as described above, after heat lamination with other oversheets, A blank card is manufactured by cutting into a predetermined card size. After that, by irradiating the blank card with laser light energy and black marking, for example, personal information can be deeply applied to the card. However, laser marking is a monochrome image or a character, and when a color image is required, color printing by a sublimation indirect thermal transfer method is generally used. As described above, in the sublimation type indirect thermal transfer method, after transferring the sublimation ink of the ink ribbon to the base transparent film such as a PET film, the PET film is pasted on the outermost surface of the card, or transferred to the PET film. For example, a method of applying a protective coat after the transferred image is retransferred to a card. In these methods, first, the former card becomes PET film / ink layer / transparent laser marking layer rather than the outermost layer, and there is a problem that the card becomes thicker by the thickness of the PET film. When black marking is performed by irradiating such a card with laser light energy, the laser light energy absorber uniformly dispersed in the transparent laser marking sheet absorbs the laser light energy and generates high heat. Therefore, “fluff” is generated between the PET film / ink layer / transparent laser marking layer. Due to the “bulge”, the visibility of the black marking is significantly reduced. In the latter, such a problem is unlikely to occur. However, since the PET film becomes a waste material by retransfer, it is not environmentally preferable. By using the transparent laser marking sheet of the present invention, there is no such problem, and a desired color image can be printed on the card, so that the use value can be increased.

[12] For electronic passport:
Moreover, the transparent laser marking sheet in this embodiment can be suitably used for an electronic passport data page or the like.

  There are two basic types of electronic passport data pages. The IC chip type is oversheet (transparent) / oversheet (transparent laser marking sheet) / core sheet (white) / inlet sheet / hinge sheet / core. Sheet (white) / oversheet (transparent laser marking sheet) / oversheet (transparent). The IC chipless type is oversheet (transparent) / oversheet (transparent laser marking sheet) / core sheet (white) / Hinge sheet / core sheet (white) / over sheet (transparent laser marking sheet) / over sheet (transparent). These various sheets are cut into a predetermined shape, and an electronic passport data page is manufactured by heat lamination as in the card laminate manufacturing process.

[13] Matting:
The transparent laser marking sheet, core sheet, and other sheet surfaces are preferably matted with an average roughness (Ra) of 0.1 to 5 μm. As described above, the reason why the mat processing is appropriately and selectively formed on the surface of each of the above-mentioned sheets is that offset printing is performed on one side of the core sheet when heating and laminating to obtain a plastic card and an electronic passport data page. Although there is a step of performing color printing, in this step, the sheet is conveyed by a conveyor and put into a printing machine. However, if an appropriate mat processing is not performed, the sheet does not slide and causes a problem in conveying the sheet. Further, other sheets similarly have problems in the transportability in the transport process, which hinders mass production. Further, in the process of heating and laminating a plurality of various sheets, there is a problem in that bubbles between the sheets are difficult to be removed and a “bulge” on the surface of the card or data page is generated.

  When the average roughness (Ra) of the sheet surface is less than 0.1 μm, as described above, the sheet conveyance problem and the “bubble” problem during heating lamination occur, but the average roughness (Ra) of mat processing exceeds 5 μm. In the core sheet, there is a problem in printability, and in the oversheet, the mat processing on the sheet surface is not crushed by heating / pressurization in the heat lamination process, leaving irregularities on the card or data page surface, color printing or laser The visibility of the marking image is not preferable.

[14] Laser marking method:
The transparent laser marking sheet in the present embodiment is one that develops color by irradiating laser light energy. Examples of the laser light energy include gas lasers such as He—Ne laser, Ar laser, CO ₂ laser, and excimer laser, and YAG. Examples of the laser include solid lasers such as a laser, Nd · YVO ₄ laser, semiconductor lasers, and dye lasers. Of these, YAG laser and Nd · YVO ₄ laser are preferable.

  In the laser marking method of this embodiment, the laser beam of laser light energy may be single mode or multimode. Further, in addition to a beam diameter reduced to 20 to 40 μm, a beam diameter as wide as 80 to 100 μm can be used. However, in the single mode, a beam diameter of 20 to 40 μm is preferable from the viewpoint of obtaining a print quality with a good contrast by setting the contrast between the print coloring portion and the base to 3 or more.

  In this way, when the transparent laser marking sheet of this embodiment is irradiated with laser light energy, the laser light energy absorber uniformly dispersed in the transparent laser marking sheet absorbs the laser light energy and generates high heat. The polycarbonate resin of the single-layer transparent laser marking sheet or the polycarbonate resin which is the core layer resin in the three-layer structure is colored black by the high heat, thereby marking characters and images in the transparent laser marking sheet.

[15] Color printing and laser marking method:
More preferably, it is a laser marking method for performing color printing and laser marking on the transparent laser marking sheet described so far. A transparent laser marking sheet on which an ink receiving layer is formed is used as an oversheet, and a heated laminate is formed in the card configuration so that the ink receiving layer side is the outermost layer of the card. After color printing by the sublimation direct thermal transfer method from the card surface, a monochrome image and characters are marked by laser light energy irradiation to form a color image, monochrome (black) image, and characters. Of course, sublimation type indirect thermal transfer system color printing can be used instead of the sublimation type indirect thermal transfer system, but the sublimation type direct thermal transfer system is more preferable because of the problems described above.

  Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto. In the following examples and comparative examples, “parts” and “%” mean parts by mass and mass% unless otherwise specified. Various evaluations and measurements in the examples were evaluated and measured by the following methods.

[1] Transparency of a transparent laser marking sheet provided with an ink receiving layer:
For the transparent laser marking sheets of Examples 1 to 6 and Comparative Examples 1 to 5, the total light transmittance of each sheet was measured using a spectrophotometer (trade name “NDH 2000” manufactured by Nippon Denshoku Industries Co., Ltd.). The transparency of the sheet was determined at the following evaluation level.
A: Total light transmittance 80% or more ○: Total light transmittance 60% or more and less than 80% X: Total light transmittance 60% or less [2] Adhesiveness between ink receiving layer and substrate sheet:
The transparent laser marking sheets of Examples 1 to 6 and Comparative Examples 1 to 5 were subjected to a cross-cut test (lattice pattern: 25) for the adhesion between the ink receiving layer and the base sheet in accordance with JIS K 5600. The adhesion between the ink receiving layer and the substrate sheet was evaluated at the following evaluation levels.
◎: No peeling at all ○: No more than 5 peelings △: No more than 10 peelings ×: 10 to 20 peelings XX: All peeling [3] Color printability:
The transparent laser marking sheets of Examples 1 to 6 and Comparative Examples 1 to 5 are used as oversheets, and the sheet B produced in Production Example 2 is used as a core sheet, resulting in an oversheet / core sheet / core sheet / oversheet layer structure. In the same way, using a rotary vacuum press (manufactured by Nissei Plastic Industry Co., Ltd.), a blank card which is punched after being pressed to a total thickness of about 700 μm with a tact time of 2 minutes at a heating temperature of 160 ° C. and a surface pressure of 10 MPa. Got. These blank cards were subjected to color printing using a double-sided card printer (product name: PR5350, manufactured by Nisca Co., Ltd.), and the printing situation was observed with the naked eye and visually evaluated at the following evaluation levels.
○: No color blur or color jump, slightly low density but good color printing △: No color blur or color jump but low density ×: Color blur or color jump is observed, density is extremely low

[4] Laser marking property:
Using the Nd • YVO ₄ laser marker (trade name “RSM10E” manufactured by Roffincinal Co., Ltd.) on the part of the blank card manufactured in [3] which is not subjected to color printing, irradiation conditions, frequency 30 KHz, current After irradiating laser light energy at 28 A and an irradiation speed of 400 mm / sec, the laser marking property was evaluated at the following evaluation level.
○: Contrast ratio of 3 or more, no bulge in laser light energy irradiation part Δ: Contrast ratio of less than 2-3 or slight bulge in laser light energy irradiation part ×: Contrast ratio of less than 2 or many bulges in laser light energy irradiation part Yes

(Production Example 1) single-layer sheet A: Transparent laser marking monolayer sheet of polycarbonate resin (trade name "TARFLON FN2200A" manufactured by Idemitsu Kosan Co., Ltd., melt volume rate ⁼ 12cm 3 / 10min) 100 parts, as the laser beam energy absorber Carbon black (Mitsubishi Chemical Corporation # 10, average particle size 95 nm, DBP oil absorption 86 ml / 100 g) 0.0015 parts, n-octadecyl-3- (3,5-di-t as phenolic antioxidant -Butyl-4-hydroxyphenyl) propionate (trade name “Irganox 1076”, manufactured by Ciba Specialty Chemicals Co., Ltd.) 0.1 part, and 2- (2′-hydroxy-3 ′) as an ultraviolet absorber , 5′-di-t-butylphenyl) -5-chlorobenzotriazole (trade name “Tinubi 329 ", manufactured by Ciba Specialty Chemicals Co., Ltd.), 0.2 parts by T-die extruder, the total sheet thickness is 100 μm, and the average surface roughness (Ra) on both sides of the sheet is 0.5. The single-layer sheet A was obtained by mat processing so as to be ˜1.8 μm.

(Production Example 2) Single-layer sheet B: White single-layer sheet Amorphous aromatic polyester resin (trade name “Easter GN071” manufactured by Eastman Chemical Co., Ltd.) 100 parts, calcium stearate 0.1 part as a lubricant and oxidation Single-layer sheet by blending 15 parts of titanium and mat processing so that the total sheet thickness is 250 μm and the average surface roughness (Ra) on both sides of the sheet is 0.5 to 1.8 μm using an extruder with a T-die. B was obtained.

(Production Example 3) Multilayer Sheet C: Transparent Laser Marking Multilayer Sheet As a resin composition constituting the skin layer, 100 parts of an amorphous aromatic polyester resin (trade name “Easter GN071” manufactured by Eastman Chemical Co., Ltd.) As a lubricant, 0.1 part of calcium stearate was blended to prepare a resin composition constituting the skin layer. On the other hand, as a resin composition constituting the core layer, a polycarbonate resin (trade name "TARFLON FN2200A" manufactured by Idemitsu Kosan Co., Ltd., melt volume rate ⁼ 12cm 3 / 10min) 100 parts of carbon black as a laser beam energy absorber (Mitsubishi Chemical Co., Ltd. # 10, average particle diameter 75 nm, DBP oil absorption 86 ml / 100 gr) 0.0015 part, phenolic antioxidant (n-octadecyl-3- (3,5-di-t-butyl-) 2- (2′-hydroxy-3 ′, 5′-di-t) using 0.1 part of 4-hydroxyphenyl) propionate (“Irganox 1076” manufactured by Ciba Specialty Chemicals Co., Ltd.) and an ultraviolet absorber. -Butylphenyl) -5-chlorobenzotriazole (trade name “Tinuvin 327”, Ciba Special 0.2 parts of T. Chemicals Co., Ltd. was blended to prepare a resin composition constituting the core layer.The skin layer-constituting resin composition and the core layer-constituting resin composition prepared above were each prepared in two units. Using a two-type three-layer extruder with a T-die, two types of three-layer coextrusion molding consists of three layers of skin layer / core layer / skin layer, the total thickness of the sheet is 100 μm, and the skin layers on both sides are Multi-layer sheet with mat processing so that the core surface layer is 15 μm, the core layer is 70 μm (core layer thickness ratio is 70% of the total thickness), and the average surface roughness (Ra) on both sides of the sheet is 0.5 to 1.8 μm C was obtained.

  Using the transparent laser marking sheets of Production Examples 1 and 3 described above, transparent laser marking sheets E to R coated with a coating agent for forming an ink receiving layer were obtained.

[Example 1] (Transparent laser marking sheet E with ink receiving layer)
As the base sheet, the single-layer sheet A (thickness: 100 μm) produced in Production Example 1 was used. Vinyl chloride-vinyl acetate copolymer (manufactured by Nissin Chemical Industry Co., Ltd., Solvain CN (vinyl chloride / vinyl acetate content = 89/11, polymerization degree = 750), ethyl cellosolve / butyl cellosolve / dioxane = 1/1 / 2 (mass ratio) was dissolved in a mixed solvent to prepare an ink receiving layer forming agent (coating liquid) having a solid content concentration of 20% using an automatic film applicator (manufactured by Yasuda Seiki Seisakusho Co., Ltd.) Transparent laser marking in which the coating liquid prepared above is applied to one side of the single-layer sheet A and then dried at a temperature of 110 ° C. to form an ink receiving layer having an average coating thickness of 6 to 8 μm after drying. Sheet E was obtained.

[Example 2] (Transparent laser marking sheet F with ink receiving layer)
As the base sheet, the single-layer sheet A (thickness: 100 μm) produced in Production Example 1 was used. Vinyl chloride-vinyl acetate copolymer emulsion (Nissin Chemical Industry Co., Ltd., Viniblanc 603 (vinyl chloride / vinyl acetate content = 70/30, solid content concentration = 50%), ethyl cellosolve / butyl cellosolve = 1/1 An ink-receiving layer forming agent (coating solution) having a solid content concentration of 20% was prepared by diluting with a mixed solvent, and using the automatic film applicator (manufactured by Yasuda Seiki Seisakusho Co., Ltd.), After coating the coating liquid prepared above on one side of A, drying is performed at a temperature of 110 ° C. to obtain a transparent laser marking sheet F on which an ink receiving layer having an average coating thickness of 6 to 8 μm after drying is formed. It was.

[Example 3] (Transparent laser marking sheet G with ink receiving layer)
As the base sheet, the single-layer sheet A (thickness: 100 μm) produced in Production Example 1 was used. Vinyl chloride-acrylic copolymer emulsion (manufactured by Nissin Chemical Industry Co., Ltd., Viniblanc 690 (vinyl chloride / acrylic content = 80/20, solid content concentration = 54%), ethyl cellosolve / butyl cellosolve = 1/1 ( (Mass ratio) The mixture was diluted with a mixed solvent to prepare an ink-receiving layer forming agent (coating solution) having a solid content concentration of 20%, using an automatic film applicator (manufactured by Yasuda Seiki Seisakusho Co., Ltd.). After coating the coating liquid prepared above on one side of the sheet A, the transparent laser marking sheet G formed with an ink receiving layer having an average coating thickness of 6 to 8 μm after drying at a temperature of 110 ° C. Obtained.

[Example 4] (Transparent laser marking sheet H with ink receiving layer)
As the base sheet, the single-layer sheet A (thickness: 100 μm) produced in Production Example 1 was used. Ethylene-vinyl chloride-vinyl acetate copolymer emulsion (manufactured by Sumika Chemtex Co., Ltd., Sumikaflex S-830 (ethylene / vinyl chloride / vinyl acetate content = 20/50/30, solid content concentration = 50%)) Then, diluted with a mixed solvent of ethyl cellosolve / butyl cellosolve = 1/1 (mass ratio) to prepare an ink-receiving layer forming agent (coating solution) having a solid content concentration of 20% Automatic film applicator (Yasuda Seiki Co., Ltd.) After the coating solution prepared above was applied to one side of the single-layer sheet A using a manufacturing method, the ink was received at a temperature of 110 ° C., and the average coating thickness after drying was 6 to 8 μm. A transparent laser marking sheet H having a layer formed thereon was obtained.

[Example 5] (Transparent laser marking sheet J with ink receiving layer)
As the base sheet, the single-layer sheet A (thickness: 100 μm) produced in Production Example 1 was used. Application of sulfonic acid group-containing polyester resin solution (manufactured by Takamatsu Yushi Co., Ltd., Pesresin A-1120, isopropyl alcohol 26 wt% / n-propyl alcohol 12 wt% / water 42 wt% mixed solvent, solid content concentration = 20%) The coating liquid prepared above was applied to one side of the single-layer sheet A using Ta (manufactured by Yasuda Seiki Seisakusho Co., Ltd.), then dried at a temperature of 110 ° C., and the average coating thickness after drying Obtained a transparent laser marking sheet J having an ink receiving layer of 6 to 8 μm.

[Example 6] (Transparent laser marking sheet K with ink receiving layer)
As the base sheet, the multilayer sheet C (thickness: 100 μm) produced in Production Example 3 was used. Vinyl chloride-vinyl acetate copolymer (manufactured by Nissin Chemical Industry Co., Ltd., Solvain CN (vinyl chloride / vinyl acetate content = 89/11, polymerization degree = 750), ethyl cellosolve / butyl cellosolve / dioxane = 1/1 / 2 (mass ratio) was dissolved in a mixed solvent to prepare an ink receiving layer forming agent (coating liquid) having a solid content concentration of 20% using an automatic film applicator (manufactured by Yasuda Seiki Seisakusho Co., Ltd.) Transparent laser marking in which the coating liquid prepared above is applied to one side of the single-layer sheet A and then dried at a temperature of 110 ° C. to form an ink receiving layer having an average coating thickness of 6 to 8 μm after drying. Sheet K was obtained.

[Comparative Example 1] (Transparent laser marking sheet P with ink receiving layer)
As the base sheet, the single-layer sheet A (thickness: 100 μm) produced in Production Example 1 was used. Water-dispersed polyester resin (manufactured by Toyobo Co., Ltd., Vironal MD-1200 (solid content concentration 34%, butyl cellosolve 11%) is used with the above-mentioned monolayer base using an automatic film applicator (manufactured by Yasuda Seiki Seisakusho Co., Ltd.). After coating on one side of the material sheet A, it was dried at a temperature of 110 ° C. to obtain a transparent laser marking sheet P on which an ink receiving layer having an average coating thickness after drying of 6 to 8 μm was formed.

[Comparative Example 2] (Transparent laser marking sheet Q with ink receiving layer)
As the base sheet, the single-layer sheet A (thickness: 100 μm) produced in Production Example 1 was used. Acrylic emulsion (Takamatsu Oil & Fat Co., Ltd., prototype SNX-25 (solid content concentration 37%) is diluted by adding a mixed solvent of ethyl cellosolve / butyl cellosolve 1/1 (mass ratio), and coating with a solid content concentration of 22% Using an automatic film applicator (manufactured by Yasuda Seiki Seisakusho Co., Ltd.), the coating solution was coated on one side of the single-layer sheet A, dried at a temperature of 110 ° C., and the average coating film after drying. A transparent laser marking sheet Q having an ink receiving layer having a thickness of 6 to 8 μm was obtained.

[Comparative Example 3] (Transparent laser marking sheet R with ink receiving layer)
As the base sheet, the single-layer sheet A (thickness: 100 μm) produced in Production Example 1 was used. After adjusting the vinyl chloride polymer emulsion (Nissin Chemical Industry Co., Ltd., VINYBRAN 985 (solid content concentration 37%) by adding ethyl cellosolve / butyl cellosolve = 1/1 mixed solvent to a solid content concentration of 22%. The coating liquid was coated on one side of the single-layer sheet A using an automatic film applicator (manufactured by Yasuda Seiki Seisakusho Co., Ltd.), then dried at a temperature of 110 ° C., and the average coating film after drying A transparent laser marking sheet R having an ink receiving layer with a thickness of 6 to 8 μm was obtained.

[Comparative Example 4] (Ink receiving layer non-transparent laser marking sheet S)
As the base sheet, the single-layer sheet A (thickness 100 μm) produced in Production Example 1 was used as it was.

[Comparative Example 5] (Ink-receiving layer non-transparent laser marking sheet T)
As the base sheet, the multilayer sheet C (thickness: 100 μm) produced in Production Example 3 was used as it was.

  Various evaluations were performed on the transparent laser marking sheets (E to H and J to K) obtained in Examples 1 to 6 and the transparent laser marking sheets (P to T) obtained in Comparative Examples 1 to 5. The results are shown in Table 1.

(Discussion)
As shown in Tables 1 and 2, the ink-receiving transparent laser marking sheets in Examples 1 to 6 have high total light transmittance and excellent transparency, and adhesion between the ink-receiving layer coating material and the substrate. It was excellent. Furthermore, in sublimation type direct thermal transfer color printing, there is no color blur and color distortion, sufficient density, good printability, and laser marking by laser light irradiation has high contrast and irradiation. It was confirmed that it had excellent performance such as obtaining a marking with excellent smoothness that was not observed in the part. On the other hand, Comparative Examples 1 to 5 have high total light transmittance, excellent transparency, and excellent adhesion between the ink receiving layer coating material and the base material. In addition, the density was insufficient, the density was insufficient, and the color printability was poor. In Comparative Example 2, the transparency and the adhesion between the ink receiving layer coating material and the substrate are good, but the color printability and laser marking properties are poor. In Comparative Example 3, the adhesion between the ink-receiving layer coating material and the substrate was extremely poor, and no coating layer was formed on the substrate. Comparative Examples 4 and 5 are examples in which the ink receiving layer is not formed on the substrate, and are inferior in color printability.

  The present invention can be applied to transparent laser marking sheets useful for electronic passports, plastic cards, etc., which can perform color printing with excellent color development and sharpness by sublimation thermal transfer printing and also have a laser marking printing function. is there.

1 (1A), 1 (1B): Transparent laser marking sheet,
2, 20: base material sheet,
3: Ink receiving layer,
4: Skin layer,
5: Core layer,
6: Core sheet,
7: Inlet sheet,
8: Oversheet
9: Core sheet,
11: Hinge sheet,
12: Overhang part,
13: sewing machine binding
14: Plastic card
15 (15A), 15 (15B): Electronic passport data page.

Claims (11)

A transparent laser marking sheet provided with an ink receiving layer on at least one side of a transparent base sheet for laser marking,
The transparent substrate sheet is made of a transparent polycarbonate resin composition containing 0.0005 to 1 part by mass of a laser beam energy absorber with respect to 100 parts by mass of a transparent resin mainly composed of a polycarbonate resin, and has a thickness of 50 to 200 μm. As a single layer sheet having a total light transmittance of 70% or more,
Alternatively, the transparent resin layer having a skin layer and a core layer and formed of at least three layers coextruded by a melt coextrusion method, and the skin layer is mainly composed of an amorphous aromatic polyester resin The core layer is a transparent polycarbonate resin composition layer containing 0.0005 to 1 part by mass of a laser light energy absorber with respect to 100 parts by mass of a transparent resin mainly composed of a polycarbonate resin, and has a total sheet thickness. 50 to 200 μm, the thickness ratio of the core layer to the total thickness is 20 to 80%, the total light transmittance is configured as a multilayer sheet of 70% or more,
The ink receiving layer is made of a vinyl chloride copolymer or a polyester-based resin having a functional group, and has a dry film thickness of 1 to 1 on one side of the single-layer sheet or multilayer sheet in a solvent or water-based solution. A transparent laser marking sheet configured as a layer having a thickness of 20 μm.   The transparent laser marking sheet according to claim 1, wherein the laser light energy absorber of the transparent laser marking sheet contains one or more selected from carbon black, titanium black, and metal oxide.   The single-layer sheet is a transparent polycarbonate resin composition composed of 100 parts by weight of a transparent resin mainly composed of a polycarbonate resin and 0.01 to 3 parts by weight of a lubricant. The transparent laser marking sheet according to claim 1 or 2, comprising 1 to 5 parts by mass and 0.1 to 5 parts by mass of an ultraviolet absorber and / or a light stabilizer.   The skin layer constituting the multilayer sheet is a non-crystalline aromatic polyester resin composition comprising 100 parts by mass of a transparent resin mainly composed of non-crystalline aromatic polyester resin and 0.01 to 3 parts by mass of a lubricant, The transparent laser according to claim 1 or 2, further comprising 0.1 to 5 parts by mass of an antioxidant and / or anti-coloring agent and 0.1 to 5 parts by mass of an ultraviolet absorber and / or a light stabilizer. Marking sheet. 5. The melt volume rate measured according to ISO 1133 for the polycarbonate resin constituting the core layer of the single-layer sheet and the multilayer sheet is 4 to ³⁰ cm 3/10 minutes. 5. Transparent laser marking sheet.   6. The copolymerization ratio between vinyl chloride and another monomer in the vinyl chloride copolymer is at least 30% by mass of vinyl chloride and an average degree of polymerization of 100 to 2000. 6. Transparent laser marking sheet.   Copolymerization components other than vinyl chloride of the vinyl chloride copolymer are vinyl ester, acrylic acid, methacrylic acid, acrylic acid ester, methacrylic acid ester, olefin, acrylonitrile, styrene, vinylidene chloride, vinyl ether, and aromatic vinyl compound. The transparent laser marking sheet according to any one of claims 1 to 6, wherein the transparent laser marking sheet is one or more selected.   The transparent laser marking sheet according to any one of claims 1 to 7, wherein the polyester resin having the functional group is a polyester resin having a sulfonate group or a carboxylate group.   It is an object for plastic cards, The transparent laser marking sheet as described in any one of Claims 1-8.   It is an object for electronic passports, The transparent laser marking sheet as described in any one of Claims 1-8. A method for color printing and laser marking on a transparent laser marking sheet provided with the ink receiving layer according to any one of claims 1 to 10,
After color printing is performed on the surface of the transparent laser marking sheet on which the ink receiving layer is formed by a sublimation direct thermal transfer method or a sublimation type indirect thermal transfer method, laser light energy is irradiated from the surface on which the ink receiving layer is provided. A laser marking method for laser marking characters, figures, symbols, or information.

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