JP2010194757A - Transparent laser marking multilayer sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transparent laser marking multilayer sheet which is excellent in laser marking property, has high contrast between ground color and a printed part, provides a clear letter, mark and image, and has sheet conveyance property, release property from a mold after heat press, heat resistance and folding property, in combination. <P>SOLUTION: This invention relates to the transparent laser marking multilayer sheet 1 which includes at least three layers of skin layers 3a and a core layer 3b, and is molded through co-extrusion. The skin layers 3a as both the outermost layers of the multilayer sheet are made of transparent resin layer consisting essentially of polycarbonate resin. The core layer 3b consists of transparent polycarbonate resin composition layer which contains 0.0005 to 1 pts.mass of laser beam energy absorption material, based on 100 pts.mass of transparent resin essentially comprising polycarbonate resin. The whole thickness of the multilayer sheet is 50 to 300 μm, and a proportion of the thickness of the core layer 3b to the total thickness of the multilayer sheet is 20 to 80%. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a laser marking multilayer sheet. In particular, a laser that is marked without damage to the multilayer sheet by laser beam irradiation, has a high contrast between the fabric color and the printed part, can produce clear characters, symbols, and images, and has excellent heat resistance and wear resistance. The present invention relates to a marking multilayer sheet and is suitably used for an electronic passport or a plastic card.

  As international exchange progresses, the movement of human resources has become active, and so-called identification cards such as ID cards, IC cards, or passports that record personal information are used as means for identifying individuals and proving their identity. ID, etc.), in particular, the importance of ID issued by public institutions and highly reliable organizations is increasing.

  In particular, since the September 2001 global terrorist attacks, countermeasures such as tightening immigration control in each country have been taken. For example, the United Nations specialized organization ICAO (International Civic Aviation Organization) has established a standard, and has started to introduce an electronic passport incorporating an IC chip that can write and read personal information. In addition, ID cards, IC cards, and the like on which a large amount of information is recorded to identify individuals have also appeared. These ID cards, IC cards, or so-called identification cards such as passports display personal information such as personal names, symbols, characters, and photographs on the card body and sheet body in addition to the IC chip on which personal information is written. Things have become commonplace.

  By the way, such an ID card, IC card, or passport can identify and prove an individual, so that a third party other than a public organization or a highly reliable organization can alter or forge personal information. If it can be done easily, etc., the credibility of the ID card will be reduced, which may hinder the progress of international exchange and the movement of human resources on a global scale.

  Therefore, how to prevent tampering and forgery is an important problem in the above-described identification such as an electronic passport, an ID card, and an IC card. That is, it is important how a high-contrast and clear display can be obtained for a light and thin electronic passport, an ID card, an IC card, etc., because it leads to prevention of tampering and counterfeiting.

  In order to solve such a problem, a technique for laser marking personal names, symbols, characters, photographs, and the like, specifically, a multilayer sheet for laser marking has been attracting attention.

  In Patent Document 1, a multilayer sheet comprising at least a surface layer and an inner layer is provided for the purpose of obtaining a multilayer sheet that can be laser-marked with no appearance damage, good contrast, and excellent surface smoothness. (B-2) 0.01 to 5 parts by weight of an energy absorber that absorbs a laser beam and (b-3) with respect to 100 parts by weight of the thermoplastic resin (B) and (b-1) thermoplastic resin ) A multilayer sheet for laser marking is disclosed in which an inner layer made of a thermoplastic resin composition containing 0.5 to 7 parts by weight of a colorant is formed by melt coextrusion.

In Patent Document 2, the first surface layer / inner layer / second layer is used for the purpose of obtaining a multilayer sheet having no damage to the appearance, good contrast, excellent surface smoothness and excellent heat resistance. A multi-layer sheet comprising a surface layer, wherein (A) a transparent first resin composition comprising a thermoplastic resin composition containing 0.001 to 5 parts by weight of mica and / or carbon black with respect to 100 parts by weight of a transparent thermoplastic resin. The first and second surface layers and (B) an inner layer made of a thermoplastic resin composition containing 0.001 to 3 parts by weight of an energy absorber that absorbs a laser beam with respect to 100 parts by weight of the thermoplastic resin, The thickness composition ratio of the sheet of the first surface layer / inner layer / second surface layer is 1: 4: 1 to 1: 10: 1, and the first surface layer / inner layer / second surface layer is melt coextruded. Formed laser markin Multilayer sheet is disclosed use.

  Certainly, the multilayer sheets for laser marking in Patent Documents 1 and 2 are excellent in heat-fusibility with these multilayer sheets and thermoplastic resin sheets such as PETG sheets and ABS resin sheets. A sufficient printability for printing letters and numbers by marking is obtained and deserves evaluation. However, Patent Document 1 contains 0.5 to 7 parts by weight of colorant in the inner layer, and is an intermediate layer in so-called identification cards such as ID cards, IC cards, or passports that record personal information as described above. In general, printing is performed on the inlay layer. In such a case, if the multilayer sheet is used for the outermost layer (overlay), the transparency of the printed part is not sufficient due to the influence of the colorant content, so the image clarity of the printed part is hindered. There was a problem of being. In Patent Document 2, these multilayer sheets contain mica and / or carbon black, which are laser light absorbers, on the surface layer, such as ID cards, IC cards, or passports that record personal information as described above. When the multilayer sheet is used for the outermost layer (overlay) of the so-called identification card, these laser light absorbers contained in the surface layer by laser light irradiation absorb laser light energy and cause a phenomenon such as foaming. There were problems such as reduced smoothness.

JP 2002-273732 A Japanese Patent No. 3889431

  The present invention has been made to solve the above-mentioned problems, has excellent laser marking properties, has a high contrast between the fabric color and the printed portion, and can provide clear characters, symbols, images, and a multilayer sheet. Excellent heat fusibility in the lamination process, and further improved transparency from the point of total light transmittance, sheet transportability, release from mold after hot pressing, heat resistance, bendability, resistance It is an object of the present invention to provide a laser marking multi-layer sheet having both wear characteristics. In particular, it is excellent in preventing tampering and preventing counterfeiting.

  According to the present invention, the following laser marking multilayer sheet is provided.

[1] A laser marking multilayer sheet formed by coextrusion having at least three layers having a skin layer and a core layer, wherein the skin layer as both outermost layers of the multilayer sheet has a polycarbonate resin as a main component. The core layer is composed of a transparent polycarbonate resin composition layer containing 0.0005 to 1 part by weight of a laser light energy absorbing material with respect to 100 parts by weight of a transparent resin mainly composed of a polycarbonate resin. The transparent laser marking multilayer sheet, wherein the total thickness of the multilayer sheet is 50 to 300 μm, and the ratio of the thickness of the core layer to the total thickness of the multilayer sheet is 20 to 80%.

[2] The transparent laser marking multilayer sheet according to [1], wherein the multilayer sheet has a total light transmittance of 70% or more.

[3] In the above [1] or [2], the laser light energy absorbing material contains at least one or more of carbon black, titanium black, metal oxide, metal nitride, and metal sulfide. The transparent laser marking multilayer sheet as described.

[4] The transparent laser marking according to any one of [1] to [3], wherein the carbon black, the titanium black, the metal oxide, the metal nitride, and the metal sulfide have an average particle diameter of less than 150 nm. Multi-layer sheet.

[5] The skin layer comprises a transparent polycarbonate resin composition comprising 0.01 to 3 parts by mass of a lubricant with respect to 100 parts by mass of a transparent resin mainly composed of a polycarbonate resin, and further, the skin layer and / or The core layer is 0.1 to 5 parts by mass of an antioxidant and / or an anti-coloring agent, and 0.1 to 0.1 parts by weight of an ultraviolet absorber and / or a light stabilizer with respect to 100 parts by mass of a transparent resin mainly composed of a polycarbonate resin. The transparent laser marking multilayer sheet according to any one of [1] to [4], which contains 5 parts by mass.

[6] The transparent material according to any one of [1] to [5], wherein a surface of the melt coextruded laser marking transparent multilayer sheet is matted with an average roughness (Ra) of 0.1 to 5 μm. Laser marking multilayer sheet.

  According to the present invention, the laser marking properties are excellent, and the contrast between the fabric color and the printed portion is high, and clear characters, symbols, and images are obtained, and the heat-fusibility in the lamination process of the multilayer sheet is excellent. In addition, the laser marking multilayer sheet offers improved transparency from the point of total light transmittance, sheet transportability, release from the mold after hot pressing, heat resistance, bending property, and wear resistance. An excellent effect that can be provided. In particular, it is excellent in preventing tampering and preventing counterfeiting.

It is a schematic diagram which shows one Embodiment of the laser marking multilayer sheet of this invention, Comprising: It is sectional drawing. It is a schematic diagram which shows an example in the case of using the laser marking multilayer sheet of this invention for a non-contact IC card, and is sectional drawing. It is a schematic diagram which shows the state at the time of irradiating a laser beam to the laser marking multilayer sheet of FIG. 2A, and is sectional drawing. It is a schematic diagram which shows an example in the case of using the laser marking multilayer sheet of this invention for the multilayer laminated body for electronic passports, Comprising: It is sectional drawing. It is a schematic diagram which shows the state at the time of irradiating a laser beam to the laser marking multilayer sheet of FIG. 3A, and is sectional drawing.

  Hereinafter, the form for implementing the laser marking multilayer sheet of this invention is demonstrated concretely. However, the present invention broadly includes a laser marking multilayer sheet having the invention specific matters, and is not limited to the following embodiments.

[1] The laser marking multilayer sheet 1 of the present invention is a laser marking multilayer sheet formed by coextrusion comprising at least three layers having a skin layer 3a and a core layer 3b, as shown in FIG. The skin layer 3a, which is both outermost layers of the multilayer sheet, is composed of a transparent resin layer mainly composed of polycarbonate resin, and the core layer 3b is a laser for 100 parts by mass of the transparent resin mainly composed of polycarbonate resin. The multilayer sheet comprising a transparent polycarbonate resin composition layer containing 0.0005 to 1 part by mass of a light energy absorber, the total thickness of the multilayer sheet being 50 to 300 μm, and the thickness of the core layer 3b 1 is configured as a transparent laser marking multilayer sheet 1 occupying 20 to 80% of the total thickness of 1.

[A] Configuration of multilayer sheet:
The melt coextruded transparent laser marking multilayer sheet of the present invention is a transparent multilayer sheet composed of at least three skin layers and a core layer and laminated by melt coextrusion molding.

[A-1] Three-layer sheet:
As shown in FIG. 1, the multilayer sheet according to the present embodiment is configured as a sheet having at least a three-layer structure including a skin layer 3a and a core layer 3b, and is laminated by melt coextrusion molding. The three-layer sheet according to the present embodiment is “at least three layers” and is not limited to a sheet having a three-layer structure. That is, in the transparent laser marking multilayer sheet of the present embodiment, “three-layer sheet” is for convenience of explanation, and “three-layer sheet” is “a sheet composed of at least three layers”. This is not intended to limit the sheet to “three layers”. In other words, if it is composed of 3 layers or more, it may be composed of 5 layers, 7 layers, or even more odd layers. included.

  However, even when the multilayer sheet of the present embodiment is configured from the multilayer structure described above, the skin layer described later is disposed at the outermost position of the sheet configured from the multilayer structure, and on both sides of the sheet. Further, it is necessary that the core layer be interposed between the 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.

  On the other hand, even when the multilayer sheet is composed of the above-mentioned “odd-numbered odd number layers” or more, when the multilayer sheet is too multilayered, the layer thickness per layer of the skin layer and the core layer to be arranged is thin. If it becomes too much, there is a possibility that a so-called mold stick is generated in the heating press process at the time of lamination. Accordingly, a multilayer sheet composed of 5 layers is more preferable, and a 3-layer structure is more preferable.

  Here, the reason why the multilayer sheet in this embodiment is composed of odd layers as described above is that a multilayer sheet composed of even layers always has the same structure as a multilayer sheet composed of odd layers. For example, in a multilayer sheet composed of four layers, the layers are arranged as skin layer (PC) / core layer (PC) / core layer (PC) / skin layer (PC). It is because it becomes the same structure as a multilayer sheet.

  Further, for example, in the case of a multilayer sheet composed of three layers, both one and the other are arranged so that the layers are arranged such as skin layer (PC) / core layer (PC) / skin layer (PC). Two skin layers are arranged on the outermost side, and one core layer is arranged so as to be sandwiched between the two skin layers to form a multilayer sheet. Taking a multilayer sheet composed of five layers as an example, the arrangement of layers such as skin layer (PC) / core layer (PC) / skin layer (PC) / core layer (PC) / skin layer (PC) is as follows. As is done, two skin layers may be disposed on the outermost sides of one and the other, and a multilayer sheet may be formed by alternately arranging skin layers and core layers. By forming a multi-layer sheet having a multi-layer structure in this way, it is possible to suppress so-called “swelling” due to foaming of the core layer marking portion due to laser light irradiation, and further, a skin layer is laminated on the upper layer of the core layer marking portion. Therefore, compared with the case where there is no skin layer, the abrasion resistance of the marking portion can be remarkably improved.

  The total thickness (total thickness) of the three-layer sheet may be 50 to 300 μm, and the ratio of the thickness of the core layer to the total thickness may be 20% or more and less than 80%. desirable. When the total thickness of the three-layer sheet is less than 50 μm, the core layer thickness is less than 40 μm, and the laser marking property is insufficient. In addition, when the total thickness of the three-layer sheet exceeds 300 μm, when the multilayer sheet for electronic passport and the plastic card are formed by multilayer lamination using the three-layer sheet exceeding 300 μm, the total maximum thickness which is the thickness standard of these Since there is a possibility of exceeding 800 μm, the versatility is poor and practical use becomes difficult. Furthermore, the multilayer sheet preferably has a ratio of the thickness of the core layer to the total thickness of 20% or more and less than 80%. If the thickness of the skin layer is less than 20%, so-called “fluffing” due to foaming of the core layer marking portion due to laser light irradiation cannot be suppressed, and in addition, the wear resistance of the marking portion is reduced, which is not preferable. On the other hand, if the thickness of the skin layer is too large, the thickness of the core layer laser marking portion to be described later is inevitably thinned and the laser marking property is inferior.

  By making the thickness of the entire three-layer sheet the desired thickness in this way, the laser marking property of the multilayer sheet and the wear resistance of the laser marking part (decrease in visibility due to marking part destruction due to external friction of the sheet) It becomes easy to draw out the characteristic of being excellent in. Furthermore, not only the total thickness of the entire three-layer sheet, but also the ratio of the thickness of the skin layer and the core layer constituting the three-layer sheet in the three-layer sheet is set to the above-described desired ratio, thereby providing three layers. This is preferable because the effect of the present application can be further exhibited, such as the laser marking property being easily improved, in combination with the thickness of the entire sheet being within a desired range.

  Furthermore, the total light transmittance of the multilayer sheet is preferably 70% or more. For example, when the transparent laser marking multilayer sheet of the present invention is used for a laminate sheet for an electronic passport or a laminate of a plastic card, printing is generally performed in these applications. Therefore, for example, by laminating a white sheet under the transparent laser marking multilayer sheet of the present invention, for example, the transparent laser marking multilayer sheet as the outermost layer is irradiated with laser light to develop a black color, thereby marking images and characters. It is good to let them. By manufacturing and using in this way, a clear image can be obtained with black / white contrast because the underlayer is white. That is, when laminating white sheets or the like, the clearness of the black / white contrast can be emphasized by setting the transparency of the outermost layer to the total light transmittance within the above-mentioned desired range. In other words, the transparency of the outermost layer is important for ensuring the sharpness of the black / white contrast. When the total light transmittance is less than 70%, the black / white contrast becomes insufficient and sufficient marking properties are obtained. Since problems that cannot be secured occur and printing is performed on the base white sheet, this causes a problem in the visibility of the printing, which is not preferable.

  Here, the “total light transmittance” is an index indicating the ratio of transmitted light among the light incident on the film or the like, and the total light transmittance when all the incident light is transmitted is 100%. . In the present 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).

[A-1-1] Skin layer in multilayer sheet:
The skin layer in the multilayer sheet is configured as both outermost layers disposed on the outside of the three-layer sheet. That is, this skin layer plays a role as a surface layer (both outermost layers) of a three-layer sheet disposed so as to be sandwiched from both end surface sides (outside) of the core layer in a multilayer sheet described later.

  The thicknesses of the skin layers are preferably the same. When a multilayer sheet is composed of skin layers of different thicknesses, it is common to perform laser marking from the front and back of a multilayer laminate or card for electronic passports, in which case the outermost and backmost layers of the laminate This is because it is not preferable that the thickness of the skin layer is different because the so-called “swelling” suppressing effect and the abrasion resistance effect of the marking portion due to the foaming of the core layer marking by laser light irradiation are different. Further, for example, when a multilayer sheet is composed of three layers such as skin layer (PC) / core layer (PC) / skin layer (PC), the thickness of the core layer is 20% or more and less than 80%. In some cases, the skin layer is 20% or more and less than 80% on both sides. When the thickness of the skin layer is less than 20%, the effect of suppressing the so-called “fluff” caused by foaming of the core layer marking portion by laser light irradiation and improving the wear resistance of the marking portion by laser light irradiation is not sufficient. . On the other hand, when the thickness of the skin layer is too large, the thickness of the core layer, which is a laser marking layer, is inevitably thinned, and the laser marking property is inferior.

  The skin layer is formed of a transparent resin layer mainly composed of polycarbonate resin (PC), particularly transparent polycarbonate resin. However, the polycarbonate resin to be used is not particularly limited, but those having a melt volume rate of 4 to 20 can be suitably used. If the melt volume rate is less than 4, it is meaningful in that the toughness of the sheet is improved, but the molding processability is inferior. On the other hand, a melt volume rate exceeding 20 is not preferable because the sheet has poor toughness. By forming the skin layer from a transparent resin layer mainly composed of polycarbonate resin (PC) in this way, so-called “blowing” due to foaming of the core layer marking portion by laser light irradiation is suppressed and marking by laser light irradiation is performed. The wear resistance of the part can be improved.

  It is important that the skin layer has high transparency, and there is no particular limitation as long as it is a resin, filler, etc. that does not hinder the transparency of the polycarbonate resin, but the skin layer has improved scratch resistance or improved heat resistance. For this purpose, a blend of a general-purpose polycarbonate resin and a special polycarbonate resin or a blend of a polycarbonate resin and a polyarylate resin can be used.

[A-1-2] Core layer in the multilayer sheet:
The core layer is configured as a so-called core layer disposed in the center of the three-layer sheet. That is, this core layer is formed as a core layer of a three-layer sheet so as to be sandwiched between two skin layers disposed on the outermost side. The thickness of the core layer is desirably formed so that the ratio of the thickness in the entire sheet is 20% or more and less than 80%. Preferable is 40% or more and less than 80%. When the thickness ratio of the core layer is 20% or more, the contrast with the non-colored portion due to the white background layer is increased due to the thickness effect of the core layer marking portion by laser light irradiation, and the visibility and sharpness of the marking portion are improved. On the other hand, when the thickness ratio of the core layer exceeds 80%, the effect of suppressing the so-called “swelling” by the foaming of the core layer marking by laser light irradiation and the effect of improving the wear resistance of the marking portion by laser light irradiation are not sufficient. . On the other hand, when the thickness ratio of the core layer is less than 20%, the thickness of the core layer, which is a laser marking layer, is inevitably thinned and the laser marking property is inferior.

  As a material (raw material) constituting the core layer, a polycarbonate resin, particularly a transparent polycarbonate resin is used. However, the polycarbonate resin to be used is not particularly limited, but those having a melt volume rate of 4 to 20 can be suitably used. If the melt volume rate is less than 4, it is meaningful in that the toughness of the sheet is improved, but the molding processability is inferior. On the other hand, a melt volume rate exceeding 20 is not preferable because the sheet has poor toughness.

[A-1-3] Laser light energy absorbing material:
Moreover, it is desirable that the core layer contains 0.0005 to 1 part by mass of the laser light energy absorbing material with respect to 100 parts by mass of the transparent resin mainly composed of polycarbonate resin. Such a configuration is desirable because it is excellent in laser colorability when laser-marked, the contrast between the fabric color and the printed part is increased, and clear characters, symbols, and images can be obtained.

  Examples of the laser light energy absorbing material include at least one selected from the group consisting of carbon black, titanium black, metal oxide, metal sulfide, and metal nitride. More preferably, the laser light energy absorbing material contains at least one or more of carbon black, titanium black, and metal oxide in the core layer.

  Here, the average particle diameter of carbon black, titanium black, metal oxide, metal sulfide, and metal nitride is preferably less than 150 nm, more preferably less than 100 nm, and an average particle diameter of 10 Carbon black having a dibutyl phthalate (DBT) oil absorption of 60 to 170 ml / 100 gr at ˜90 nm or titanium black or metal oxide having an average particle size of less than 150 nm is preferably used. On the other hand, 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 occur on the sheet surface. It is not preferable. Furthermore, if the average particle size of the carbon black is less than 10 nm, the laser colorability is lowered, and it is too fine to be difficult to handle. Further, if the DBT oil absorption is less than 60 ml / 100 gr, the dispersibility is poor, and if it exceeds 170 ml / 100 gr, the concealability is poor, which is not preferable.

  As the metal oxide, as the metal forming the oxide, zinc, magnesium, aluminum, iron, titanium, silicon, antimony, tin, copper, manganese, cobalt, bismuth, vanadium, niobium, molybdenum, ruthenium, tungsten, palladium, Silver, platinum, etc. are mentioned. Furthermore, ITO, ATO, AZO, etc. are mentioned as a composite metal oxide.

  Examples of the metal sulfide include zinc sulfide and cadmium sulfide. Furthermore, examples of the metal nitride include titanium nitride.

  As described above, carbon black, titanium black, metal oxide, and composite metal oxide are preferably used as the energy absorber, and each is used alone or in combination.

  Moreover, the addition amount (blending amount) of the energy absorber is 0.0005 to 1 part by mass of carbon black added (blending), more preferably 0.001 to 1 part by mass. 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 0.005 to 5 parts by mass. More preferably, it is 0.005-1 mass part.

  Thus, the addition amount (blending amount) of the energy absorber is adjusted to a desired amount because the multilayer sheet is preferably transparent. That is, in many cases, coloring, images, characters, etc. are printed on the core layer of the multilayer sheet, and if the skin layer laminated on the core layer is inferior in transparency in that case, the printed coloring, image The characters and the like become unclear and become a practical problem. For this purpose, carbon black having a small average particle size is preferably used, and a mixture of carbon black and at least one selected from other metal oxides, metal sulfides, and metal nitrides is used as a laser energy absorber. The average particle size of these metal oxides, metal sulfides, and metal nitrides is at least less than 150 nm, preferably less than 100 nm.

  Therefore, when the average particle diameter of these laser energy absorbers exceeds 150 nm, the transparency of the transparent laser marking multilayer sheet A is undesirably lowered. Moreover, when the compounding amount of these laser energy absorbers exceeds 1 part by mass, the transparency of the multilayer sheet is lowered, and the amount of absorbed energy is too much, thereby deteriorating the resin. As a result, sufficient contrast cannot be obtained. On the other hand, if the addition amount of the laser energy absorber is less than 0.0005 parts by mass, a sufficient contrast cannot be obtained, which is not preferable.

[A-1-4] Lubricant, antioxidant and / or anti-coloring agent:
Moreover, in this embodiment, it is preferable to make a skin layer contain a lubricant. This is because the inclusion of the lubricant can prevent fusion to the press plate at the time of hot pressing. Furthermore, in this embodiment, it is also preferable that the skin layer and / or the core layer contain an antioxidant and / or an anti-coloring agent, and an ultraviolet absorber and / or a light stabilizer as necessary. Addition (compounding) of an antioxidant and / or an anti-coloring agent effectively acts on physical property reduction and hue stabilization due to molecular weight reduction during molding processing. As this antioxidant and / or anti-coloring agent, a phenol-based antioxidant or a phosphite-based anti-coloring agent is used. Further, the addition (formulation) of an ultraviolet absorber and / or a light stabilizer effectively acts to suppress the light deterioration resistance during storage of the transparent multilayer sheet and during actual use of the electronic passport or plastic card as the final product.

  Examples of phenolic antioxidants include, for example, α-tocopherol, butylhydroxytoluene, sinapir 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-t-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2-tert-butyl-6- (3′-tert-butyl-5′-methyl-2′-hydroxybenzyl)- -Methylphenyl 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-p-cresol), 2,2′-ethylidene-bis (4 6-di-tert-butylphenol), 2,2′-butylidene-bis (4-methyl-6-tert-butyl) Enol), 4,4′-butylidenebis (3-methyl-6-tert-butylphenol), triethylene glycol-N-bis-3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate, 1 , 6-Hexanediol bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], bis [2-tert-butyl-4-methyl 6- (3-tert-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-tert-butyl) -M-cresol), 4,4'-thiobis (3-methyl-6-tert-butylphenol), 2,2'-thiobis (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-tert-butylphenol) 2,2-thiodiethylenebis- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2,4-bis (n-octylthio) -6- (4-hydroxy-3 ', 5'-di-tert-butylanilino) -1,3,5-triazine, N, N'-hexamethylenebis- (3,5-di-tert-butyl-4-hydroxy Hydrocinnamide), N, N′-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyl] hydrazine, 1,1,3-tris (2-methyl-4-hydroxy-5- tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, tris (3,5-di-tert- Butyl-4-hydroxyphenyl) isocyanurate, tris (3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate, 1,3,5-tris (3,5-di-tert-butyl-4- Hydroxybenzyl) isocyanurate, 1,3,5-tris (4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanurate 1,3,5-tris2 [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-tert-butyl-hydroxyphenyl) propionate, 1,3,5-trimethyl-2,4,6-tris (3, 5-di-tert-butyl-4-hydroxybenzyl) benzene, 1,3,5-tris (3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate, tetrakis [3- (3,5- Di-tert-butyl-4-hydroxyphenyl) propionyloxymethyl] methane is preferred, and n-octadecyl-3- (3,5-di-tert-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 the phosphite ester colorant include triphenyl phosphite, tris (nonylphenyl) phosphite, tridecyl phosphite, trioctyl phosphite, trioctadecyl phosphite, didecyl monophenyl phosphite, and dioctyl monophenyl. Phosphite, diisopropyl monophenyl phosphite, monobutyl diphenyl phosphite, monodecyl diphenyl phosphite, monooctyl diphenyl phosphite, 2,2-methylenebis (4,6-di-tert-butylphenyl) octyl phosphite, tris ( Diethylphenyl) phosphite, tris (di-iso-propylphenyl) phosphite, tris (di-n-butylphenyl) phosphite, tris (2,4-di-tert-butylphenyl) Phosphite, tris (2,6-di-tert-butylphenyl) phosphite, distearyl pentaerythritol diphosphite, bis (2,4-di-tert-butylphenyl) pentaerythritol diphosphite, bis (2, 6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite, bis (2,6-di-tert-butyl-4-ethylphenyl) pentaerythritol diphosphite, phenylbisphenol A pentaerythritol diphosphite Bis (nonylphenyl) pentaerythritol diphosphite, dicyclohexylpentaerythritol diphosphite, and the like.

  Further, as other phosphite compounds, those that react with dihydric phenols and have a cyclic structure can be used. For example, 2,2′-methylenebis (4,6-di-tert-butylphenyl) (2,4-di-tert-butylphenyl) phosphite, 2,2′-methylenebis (4,6-di-tert- Butylphenyl) (2-tert-butyl-4-methylphenyl) phosphite, 2,2′-methylenebis (4-methyl-6-tert-butylphenyl) (2-tert-butyl-4-methylphenyl) phosphite 2,2′-ethylidenebis (4-methyl-6-tert-butylphenyl) (2-tert-butyl-4-methylphenyl) phosphite.

  Among these, tris (2,4-di-tert-butylphenyl) phosphite is particularly preferable. 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.

  Examples of the ultraviolet absorber include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-tert-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], condensate with methyl-3- [3-tert-butyl-5- (2H-benzotriazol-2-yl) -4-hydroxyphenylpropionate-polyethylene glycol The benzotriazole type compound represented by can be mentioned.

  Further, examples of the ultraviolet absorber include 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5-hexyloxyphenol, 2- (4,6-bis (2,4). Examples thereof include hydroxyphenyl triazine compounds such as -dimethylphenyl) -1,3,5-triazin-2-yl) -5-hexyloxyphenol.

  Furthermore, as an ultraviolet absorber, for example, 2,2′-p-phenylenebis (3,1-benzoxazin-4-one), 2,2′-m-phenylenebis (3,1-benzoxazine-4) -One), and cyclic imino ester compounds such as 2,2'-p, p'-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]}, polymethylpropyl 3-oxy- [4- (2,2,6,6-tetra Methyl) piperi Nil] siloxane and other hindered amines can also be included, and such light stabilizers have better performance in terms of weather resistance, etc. in combination with the ultraviolet absorbers and in some cases various antioxidants. Demonstrate.

  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, barium stearate and the like.

  More preferably, the skin layer comprises a transparent polycarbonate resin composition comprising 0.01 to 3 parts by mass of a lubricant with respect to 100 parts by mass of a transparent resin mainly composed of a polycarbonate resin. Alternatively, the core layer is 0.1 to 5 parts by mass of an antioxidant and / or anti-coloring agent, and 0.1 to 0.1 parts by weight of an ultraviolet absorber and / or a light stabilizer with respect to 100 parts by mass of a transparent resin mainly composed of a polycarbonate resin. It is to contain -5 mass parts. 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. Furthermore, if the antioxidant and / or anti-coloring agent is less than 0.1 parts by mass, problems such as thermal oxidation reaction of the polycarbonate resin in the melt extrusion process and thermal discoloration resulting therefrom tend to occur. , These additives are not preferred because they tend to cause problems such as bleeding. Furthermore, if the ultraviolet absorber and / or 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 tend to occur. It is not preferable because defects are likely to occur.

[A-1-5] Matting:
Moreover, it is preferable that mat processing is given to both surfaces of a multilayer sheet, and average roughness (Ra) is 0.1-5 micrometers. As described above, the reason for forming the mat processing on the surface of the multilayer sheet is, for example, when the configuration of the laser marking multilayer sheet of the present embodiment is hot press-molded with the multilayer sheet of the present embodiment / another multilayer sheet B. The air between the multilayer sheet of this embodiment and another multilayer sheet B is easily released, and when these multilayer sheets are transported to the lamination process, the multilayer sheets are aligned after being sucked and adsorbed and transported. When the multi-layer sheet is removed by injecting air after the layers are laminated, there is a tendency that problems such as difficulty in detachment and shifting of the lamination position even if detachment is possible unless mat processing is performed. Moreover, when the average roughness (Ra) of mat processing exceeds 5 μm, the heat-sealing property of the transparent laser marking multilayer sheet / other multilayer sheet of this embodiment tends to be lowered.

  Further, when the average roughness (Ra) of the surface is less than 0.1 μm, as described above, there is a tendency that a problem such as sticking of the sheet to the conveying machine during sheet conveyance / lamination tends to occur.

[2] Application:
Moreover, the transparent laser marking multilayer sheet in this embodiment can be suitably used for an electronic passport, a plastic card, and particularly an overlay which is the outermost layer thereof.

  For example, when the transparent laser marking multilayer sheet in this embodiment is used as a non-contact IC card, a non-contact IC card as shown in FIGS. 2A and 2B can be given as an example. Specifically, as shown in FIG. 2A, the IC-chiP • Antenna layer 23 as an inlet is the core of the non-contact IC card 21, and further on both sides of the IC-chiP • Antenna layer 23, The printing layers 25 and 25 are laminated as white). Further, the non-contact IC card 21 may be formed by laminating the transparent laser marking multilayer sheet 1 according to the present embodiment as an overlay on both sides of the printing layers 25 and 25 as inlay (white). When the non-contact IC card is formed in this way, when the laser beam 7 is irradiated, as shown in FIG. 2B, characters, figures, etc. can be clearly printed on the print layers 25, 25 as inlay (white). 2A and 2B are diagrams schematically showing a cross section when the transparent laser marking multilayer sheet in the present embodiment is used as a non-contact IC card.

  Furthermore, for example, when the transparent laser marking multilayer sheet in the present embodiment is used as a multilayer laminate for electronic passports, the multilayer laminate 31 for electronic passports as shown in FIGS. 3A and 3B can be given as an example. . Specifically, as shown in FIGS. 3A and 3B, the tail sheet 33 is the core of the multilayer laminate 31 for electronic passports, and on both sides of the tail sheet 33, the print layers 35, 35 are stacked. Furthermore, it is good to laminate | stack the transparent laser marking multilayer sheet 1 in this embodiment as a laser marking layer used as an overlay on both sides of the printing layers 35 and 35 as an inlay (white), and shape | mold the multilayer laminated body 31 for electronic passports. . When a multilayer laminate for an electronic passport is formed in this way, when irradiated with the laser beam 7, as shown in FIG. 3B, characters, drawings, etc. can be clearly printed on the print layers 35, 35 as inlays (white). FIG. 3B is a diagram schematically showing a cross section when the transparent laser marking multilayer sheet in the present embodiment is used as a multilayer laminate for an electronic passport.

  The specific examples of the non-contact IC card and the multilayer laminate for electronic passport described above are merely examples, and are not limited to these examples.

[3] Method for forming multilayer sheet:
In the present invention, in order to obtain a three-layer transparent laser marking multilayer sheet, it is desirable to laminate by a coextrusion method in which the resin composition of each layer is melt coextruded and laminated.

  Specifically, the resin composition of each layer is blended, or pelletized as necessary, and each is put into each hopper of a three-layer T-die extruder having a T-die shared, and the temperature is 200 ° C. to 280 ° C. A three-layer laminate can be formed by melting in the range of ° C. and co-extruding with a three-layer T-die and cooling and solidifying with a cooling roll or the like. The melt coextruded transparent laser marking multilayer sheet of the present invention is not limited to the above method and can be formed by a known method. For example, JP-A-10-71763 Nos. (6) to (7) ) Page.

[4] Laser marking method:
The laser marking multilayer sheet in the present embodiment is one that develops color by irradiating a laser beam. As the laser beam, a gas laser such as a He—Ne laser, an Ar laser, a CO ₂ laser, and an excimer laser, a YAG laser, Nd -Solid laser such as YVO ₄ laser, semiconductor laser, dye laser and the like. Of these, YAG laser and Nd · YVO ₄ laser are preferable.

  In addition, as described above, the above resin composition may include other additives such as a mold release agent, a stabilizer, an antioxidant, an ultraviolet absorber, and a reinforcing agent as long as the characteristics thereof are not impaired. Etc. can be added.

  In the laser marking method of the present embodiment, the laser beam may be a single mode or a multimode as the laser beam, and the beam diameter is as wide as 80 to 100 μm in addition to a beam diameter reduced to 20 to 40 μm. Although a single mode and a beam diameter of 20 to 40 [mu] m are preferable, the contrast between the print coloring portion and the background is set to 3 or more, and the print quality with good contrast is obtained.

  As described above, when the laser marking multilayer sheet of this embodiment is irradiated with a laser beam, the multilayer sheet A constituting the laser marking multilayer sheet, and more specifically, the core layer containing the laser light energy absorber is colored, which is easy. In addition, images can be drawn clearly. Furthermore, since the transparent layer of the same resin forms a skin layer on the core layer, an image marked on the core layer does not cause a difference in refractive index between the core layer and the skin layer, unlike a skin layer of a different resin. In addition, there is an effect of excellent sharpness of characters and the like, and an effect of suppressing so-called “swelling” due to foaming of the marking portion because of the transparent skin layer even when the laser beam is irradiated and marked with high power. In addition, since the transparent skin layer is formed on the marking part, for example, when it is repeatedly rubbed against other metals, glass plastics, etc., even if the skin layer is worn, the marking part is not damaged. This has the effect of maintaining the sharpness of the image and characters of the marking portion. Therefore, the laser marking multilayer sheet of the present embodiment is excellent in laser marking properties, and a clear image, characters, etc. are produced by black color development on the white underlayer with a laser beam on the surface or the interface between the support and the covering. Can be drawn easily and clearly, and personal information on an electronic passport or a plastic IC card can be marked clearly.

  EXAMPLES 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” means parts by mass and mass% unless otherwise specified. Various evaluations and measurements in the examples were performed by the following methods.

[1] Transparency of transparent laser marking multilayer sheet:
The total light transmittance of the laser marking transparent multilayer sheet was measured using a spectrophotometer (trade name “EY7000” manufactured by Macbeth).
◎: Total light transmittance 80% or more, ○: Total light transmittance 60% or more and less than 80%,
X: The total light transmittance is less than 60%.

[2] Sheet transportability:
After the transparent laser marking multilayer sheet was cut to 100 × 300 mm, it was conveyed by a sheet conveying machine, and when the sheet was placed on a predetermined position on a heating press machine die, the sheet conveying property was evaluated according to the following criteria.
○: No problem
Δ: At the time of adsorbing the sheet → conveying → desorbing, the sheet is difficult to desorb from the adsorbing part, and the sheet shifts.
X: The sheet is difficult to be detached from the adsorption part.

[3] Releasability after lamination heating press molding:
Vacuum pressing machine (manufactured by Nissei Plastic Industrial Co.) using the laminated sheet sandwiched between two chromium-plated steel plates, after pre-heating for 2 minutes at a press temperature of 100 ° C., 170 ° C., the actual surface pressure 12 kgf / cm ² at 2 minutes Retained. Then, after cooling to room temperature, the sample pinched | interposed with the chromium plating steel plate was taken out with the chromium plating steel plate, and the mold release property at the time of peeling a chromium plating steel plate from a sample was evaluated as follows.
○: Can be easily peeled, Δ: Slightly adheres to the mold and can be peeled off, but cannot be used due to scratches on the sheet surface, ×: Adheres to the mold.

[4] Air bubble removal:
As described above, the state of remaining bubbles in the laminated body after the hot pressing was observed, and the bubble releasing property was evaluated as follows.
○: No bubbles in the laminate, Δ: slight bubbles remaining in the laminate, ×: a large amount of bubbles remaining in the laminate.

[5] Heat attractiveness:
A release agent is applied to one end of the transparent laser marking (multilayer) sheet A and multilayer sheet B, sandwiched between two chrome-plated steel sheets, and then pressed at a press temperature of 100 ° C. using a vacuum press machine (manufactured by Nissei Plastic Industries). After preheating for 1 minute, the temperature was maintained at 170 ° C. and an actual pressure of 12 kgf / cm ^{2 for} 2 minutes. Then, after cooling to room temperature, the laminate sheet was taken out and manually peeled off from the part where the release agent was applied, and the heat-fusibility between the laminates was evaluated as follows.
○: No peeling and excellent heat fusion property.
Δ: Partially peeled, ×: Whole surface peeled, XX: Whole surface peeled with a small force.

[6] Laser marking property:
Using the heated laminate sheet, the laser marking property is evaluated using an Nd / YVO ₄ laser (trade name “LT-100SA”, manufactured by Laser Technology Co., Ltd., and trade name “RSM103D”, manufactured by Roffin Sinar Co.). did. Specifically, the laser marking property was determined at a laser irradiation speed of 800 mm / sec, and determined as follows from the sharpness of the image and the surface state of the marking part.
A: Excellent in sharpness, no abnormalities such as blistering in the laser light irradiation part,
○: Sharpness is good, there is no abnormality such as blistering in the laser light irradiation part,
Δ: Insufficient sharpness or slight bulge in the laser light irradiation part,
×: Poor sharpness or large swelling of the laser beam irradiation part.

[7] Abrasion resistance of transparent laser marking multilayer sheet:
The rubbing tester (manufactured by Imoto Seisakusho Co., Ltd.) was used to determine the wear resistance of the black laser marking portion obtained by irradiating the transparent laser marking multilayer and single layer sheet and core sheet heat-bonded laminate of [5] with laser light in [5]. Was used 80 times (40 reciprocations) with # 00 steel wool (load 500 gr), and the state before and after the test was judged by visual evaluation.
A: No abnormality is observed in the marking part, and there is no change in the sharpness and visibility of the image.
○: The marking portion is scraped, but the sharpness and visibility of the image are good.
(Triangle | delta): The cutting of the marking part is advancing and the clearness and visibility of an image fall.
X: The marking portion is greatly scraped, and the sharpness and visibility of the image are remarkably lowered.

(Production Example 1) Transparent laser marking multilayer sheet A:
As the skin layer, polycarbonate (trade name "TARFLON FN2500A" produced by Idemitsu Kosan Co., melt volume rate ⁼ 8cm 3 / 10min) using, as a core layer, the above polycarbonate, carbon black (manufactured by Mitsubishi Chemical Corporation as an energy absorber for absorbing a laser beam # 10, 0.0015 parts by mass of average particle diameter 75 nm, DBP oil absorption 86 ml / 100 gr) and n-octadecyl-3- (3,5-di-t-butyl-) as a phenolic antioxidant 0.1 part of 4-hydroxyphenyl) propionate (trade name “Irganox 1076”, manufactured by Ciba Specialty Chemicals) and 2- (2′-hydroxy-3 ′, 5 ′) as an ultraviolet absorber -Di-t-butylphenyl) -5-chlorobenzotriazole (product) “Tinubin 327” (manufactured by Ciba Specialty Chemicals) was blended in 0.2 part, and a transparent laser marking multilayer sheet A having three layers of skin layer / core layer / skin layer was obtained by T-die coextrusion method. . The total thickness of the sheet is 100 μm, the thicknesses of the skin layers on the front and back sides are the same, and the layer structure is a skin layer (18 μm) / core layer (64 μm) / skin layer (18 μm), The thickness ratio of the core layer was 64%. Furthermore, about the average surface roughness (Ra) of both surfaces, the 3 layer transparent laser marking multilayer sheet A by which the mat | matte process was given so that it might be set to 0.5-1.8 micrometers was obtained.

(Production Example 2) Transparent laser marking multilayer sheet B:
The total thickness of the sheet is 100 μm, the thicknesses of the skin layers on the front and back sides are the same, and the layer structure is configured as skin layer (28 μm) / core layer (44 μm) / skin layer (28 μm). A transparent laser marking multilayer sheet B was obtained in the same manner as in Production Example 1 except that the layer thickness ratio was 44%.

(Production Example 3) Transparent laser marking multilayer sheet C:
The total thickness of the sheet is 100 μm, and the thicknesses of the skin layers on the front and back sides are the same, and the layer structure is made up of a skin layer (5 μm) / core layer (90 μm) / skin layer (5 μm). A transparent laser marking multilayer sheet C was obtained in the same manner as in Production Example 1 except that the layer thickness ratio was 90%.

(Production Example 4) Transparent laser marking multilayer sheet D:
The total thickness of the sheet is 100 μm, the thicknesses of the skin layers on the front and back sides are the same, and the layer structure is a skin layer (45 μm) / core layer (10 μm) / skin layer (45 μm). A transparent laser marking multilayer sheet D was obtained in the same manner as in Production Example 1 except that the layer thickness ratio was 10%.

(Production Example 5) Core sheet E:
Non-crystalline polyester (trade name “Easter GN071” manufactured by Eastman Chemical Co., Ltd., EG / CHDM = 70/30 mol%) is used as the skin layer, and polycarbonate (trade name “Toughlon FN2500A” manufactured by Idemitsu Kosan Co., Ltd., melt volume) is used as the core layer. late ⁼ 8 cm 3 / 10min) using, as a phenolic antioxidant, (n- octadecyl-3- (3,5-di -t- butyl-4-hydroxyphenyl) propionate ( "Irganox 1076" manufactured by Ciba Specialty -0.1 part of Chemicals) and 2- (2'-hydroxy-3 ', 5'-di-t-butylphenyl) -5-chlorobenzotriazole (trade name "Tinuvin" as an ultraviolet absorber 327 ", manufactured by Ciba Specialty Chemicals Co., Ltd.) 0.2 part, and titanium oxide 5 And a core layer E of three layers of skin layer / core layer / skin layer was obtained by a T-die coextrusion method, and the total thickness of the sheet was 150 μm, and the thickness of the skin layers on the front and back sides was changed to The thickness of the layers is the same as that of the skin layer (20 μm) / core layer (110 μm) / skin layer (20 μm), and the thickness of the core layer is 73%. About (Ra), the core sheet E by which the mat | matte process was given so that it might become 0.5-1.8 micrometers was obtained.

(Production Example 6) Transparent laser marking single layer sheet F:
Polycarbonate (trade name "TARFLON FN2500A" produced by Idemitsu Kosan Co., melt volume rate ⁼ 8cm 3 / 10min) with carbon black (manufactured by Mitsubishi Chemical Corporation # 10 as an energy absorber for absorbing a laser beam, the average particle diameter of 75 nm, DBP oil absorption 86ml / 100gr) in an amount of 0.0015 parts by mass, and (n-octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate ("Irganox 1076") as a phenolic antioxidant. 0.1 parts of Ciba Specialty Chemicals Co., Ltd., and 2- (2′-hydroxy-3 ′, 5′-di-t-butylphenyl) -5-chlorobenzotriazole (as UV absorber) (Product name "Tinubin 327", manufactured by Ciba Specialty Chemicals) 0 Two parts, a transparent laser marking single layer sheet F having a total sheet thickness of 100 μm was obtained by the T-die coextrusion method, and the average surface roughness (Ra) on both sides was 0.5 to 1.8 μm, A transparent laser marking single-layer sheet F which was matted so as to be obtained was obtained.

  The above-described production examples 1 to 6 were heat-fused at 170 ° C. using a vacuum press machine (manufactured by Nissei Plastic Industry) with the configuration shown in Table 1, and as Examples 1-2 and Comparative Examples 1-3 Various evaluations were made. The results are shown in Tables 1 and 2.

(Discussion)
As shown in Tables 1 and 2, in Examples 1 and 2, all of the sheets are excellent in transparency, transportability, releasability after laminating and heating press, and air release properties, and excellent laser marking properties and marking. The part had wear resistance. In addition, although it experimented using the sheet | seat manufactured similarly to Example 1 except that there is no mat | matte process, there was no problem regarding use. However, in terms of improving the yield rate, it was confirmed that the mat processed as shown in Example 1 is preferable.

  On the other hand, in Comparative Example 1, the thickness of the skin layer of the transparent laser marking multilayer sheet C was 5 μm (thickness ratio 10%), and the foaming suppression effect of the core layer marking portion by laser light irradiation was an example. A decrease was observed as compared with that, and the abrasion resistance of the marking portion was insufficient. In Comparative Example 2, since the thickness ratio of the core layer of the transparent laser marking multilayer sheet D was 10%, the color developability of the laser marking layer was inferior. In Comparative Example 3, since the transparent laser marking single-layer sheet F was a single layer, the foaming suppression effect of the core layer marking portion due to laser light irradiation was lower than in the Examples, and the abrasion resistance of the marking portion was It was also inferior.

  The transparent laser marking multilayer sheet of the present invention is a non-PVC-based multilayer sheet, and the transparent laser marking multilayer sheet is used for an electronic passport laminate sheet and an overlay that is an outermost layer of a contact IC card, without contact with a plastic, With laser light irradiation, not only letters and numbers but also images have clear and excellent laser marking properties, and in sheet lamination and heating press processes, sheet conveyance, lamination, heat fusion, and laminates It is a multilayer sheet having excellent heat resistance without deformation of the sheet, and can be suitably used as a multilayer sheet for an electronic passport or a plastic card.

1: Laser marking multilayer sheet, 3a: Skin layer, 3b: Core layer, 7: Laser beam, 21: Non-contact IC card, 23: IC-chiP / Antenna layer, 25: Print layer, 31: Multi-layer laminate for electronic passport 33: Tail sheet, 35: Print layer.

Claims (6)

A laser marking multilayer sheet formed by coextrusion consisting of at least three layers having a skin layer and a core layer,
The skin layer, which is both outermost layers of the multilayer sheet, comprises a transparent resin layer mainly composed of a polycarbonate resin,
The core layer is composed of a transparent polycarbonate resin composition layer containing 0.0005 to 1 part by mass of a laser beam energy absorbing material with respect to 100 parts by mass of a transparent resin mainly composed of a polycarbonate resin.
A transparent laser marking multilayer sheet, wherein the total thickness of the multilayer sheet is 50 to 300 μm, and the ratio of the thickness of the core layer to the total thickness of the multilayer sheet is 20 to 80%.   The transparent laser marking multilayer sheet according to claim 1, wherein the multilayer sheet has a total light transmittance of 70% or more.   The transparent laser marking according to claim 1 or 2, wherein the laser light energy absorbing material contains at least one or two or more of carbon black, titanium black, metal oxide, metal nitride, and metal sulfide. Multi-layer sheet.   The transparent laser marking multilayer sheet according to claim 1, wherein the carbon black, the titanium black, the metal oxide, the metal nitride, and the metal sulfide have an average particle diameter of less than 150 nm. The skin layer is composed of a transparent polycarbonate resin composition comprising 0.01 to 3 parts by mass of a lubricant with respect to 100 parts by mass of a transparent resin mainly composed of a polycarbonate resin.
Furthermore, with respect to 100 parts by mass of the transparent resin whose main component is a polycarbonate resin, the skin layer and / or the core layer is 0.1 to 5 parts by mass of an antioxidant and / or a coloring inhibitor, and an ultraviolet absorber and / or Or the transparent laser marking multilayer sheet of any one of Claims 1-4 which contains 0.1-5 mass parts of light stabilizers.   The transparent laser marking multilayer according to any one of claims 1 to 5, wherein the surface of the melt coextruded laser marking transparent multilayer sheet is matted with an average roughness (Ra) of 0.1 to 5 µm. Sheet.

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