JP2010194756A - Laser marking multilayer sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a 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, is excellent in heat melting property in a lamination process, and has sheet conveyance property, release property from a mold after heat press, heat resistance and folding property, in combination. <P>SOLUTION: The laser marking multilayer sheet 1A is formed by laminating a transparent laser marking sheet A and a multilayer sheet B. The transparent laser marking sheet A is a transparent laser marking sheet 3 consisting essentially of a polycarbonate resin. The multilayer sheet B is a multilayer sheet 5 which has skin layers 5a and a core layer 5b, and is formed from at least three layers of laminated sheets, wherein the skin layers 5a as both outermost layers of the multilayer sheet B is formed from copolymerization polyester resin, and the core layer B of the multilayer sheet B consists of a colored multilayer sheet made of polycarbonate resin composition. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a laser marking multilayer sheet. In particular, the present invention relates to a laser marking multilayer sheet that is marked without damage to the multilayer sheet by irradiation with a laser beam, has a high contrast between the fabric color and the printed part, provides clear characters, symbols and images, and has excellent heat resistance. It is preferably 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 this case, when the multilayer sheet is used for the outermost layer (overlay), transparency is not sufficient due to the influence of the colorant content. Therefore, there has been a problem that the image clarity of the printed portion is hindered. 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 obtained by laminating a transparent laser marking sheet A and a multilayer sheet B, wherein the transparent laser marking sheet A is a transparent laser marking sheet formed by melt extrusion molding, and is a polycarbonate. The transparent laser marking sheet A has a total thickness of 50 while being made of a transparent polycarbonate resin composition containing 0.0005 to 1 part by mass of a laser light energy absorbing material with respect to 100 parts by mass of the transparent resin mainly composed of resin. The multilayer sheet B is a multilayer sheet having a skin layer and a core layer, and is formed by laminating at least three layers by melt extrusion molding. The skin layers, which are both outermost layers, are mainly composed of terephthalic acid units. A polyester comprising a glycol unit mainly comprising a dicarboxylic acid unit, an ethylene glycol unit (I), and a 1,4-cyclohexanedimethanol unit (II), and the ethylene glycol unit (I) and 1,4-cyclohexane dimethanol unit (II). The cyclohexanedimethanol unit (II) is made of a copolymer polyester resin in which (I) / (II) = 90-30 / 10-70 mol%, and the core layer of the multilayer sheet B is mainly composed of a polycarbonate resin. It consists of a transparent resin as a component, and the skin layer and / or the core layer of the multilayer sheet B is a resin such as a dye or a pigment with respect to 100 parts by mass of the copolyester resin and / or 100 parts by mass of the polycarbonate resin. 1 part by mass or more of at least one of the above colorants is added, and the total thickness of the multilayer sheet B is 1 Together consist 0～300Myuemu, the thickness of the core layer, the thickness proportion to the total thickness of the multilayer sheet B is 30% or more, laser marking multilayer sheet comprising a colored multilayer sheet consisting of less than 85%.

[2] Furthermore, the transparent laser marking sheet A contains 0.01 to 3 parts by mass of a lubricant with respect to 100 parts by mass of the transparent resin containing a polycarbonate resin as a main component, and with respect to 100 parts by mass of the transparent resin. The transparent laser marking sheet 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, according to [1]. Laser marking multilayer sheet.

[3] The transparent laser marking sheet A is a transparent laser marking sheet having a skin layer and a core layer and formed by melt extrusion molding. The skin layer is made of a transparent resin mainly composed of a polycarbonate resin. The core layer is made of a transparent polycarbonate resin composition containing 0.0005 to 1 part by mass of a laser light energy absorbing material with respect to 100 parts by mass of a transparent resin mainly composed of a polycarbonate resin, and the transparent laser marking sheet A The thickness of the core layer is 50 to 200 μm, and the thickness ratio of the core layer to the total thickness of the transparent laser marking sheet A is 20% to less than 90%. ] The laser marking multilayer sheet of description.

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

[5] The laser light energy absorbing material of the transparent laser marking sheet A contains at least one or more of carbon black, titanium black, metal oxide, metal sulfide, and metal nitride [1] ] The laser marking multilayer sheet according to any one of [4].

[6] The core layer and / or skin layer of the transparent laser marking sheet A and / or the multilayer sheet B is 0.1 to 5 parts by mass of an antioxidant and / or anti-coloring agent with respect to 100 parts by mass of the thermoplastic resin. The laser marking multilayer sheet according to any one of [1] to [5], which contains 0.1 to 5 parts by mass of an ultraviolet absorber and / or a light stabilizer.

[7] The surface of the transparent laser marking sheet A and / or the multilayer sheet B is subjected to mat processing with an average roughness (Ra) of 0.1 to 5 μm, according to any one of [1] to [6]. Laser marking multilayer sheet.

[8] The laser marking multilayer sheet according to any one of [1] to [7], which is for electronic passports.

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

[10] A method of laser marking the laser marking multilayer sheet according to any one of [1] to [9], wherein a laser beam is irradiated from the transparent laser marking sheet A side laminated on the laser marking multilayer sheet. Laser marking method for printing.

  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. Furthermore, the laser has improved transparency from the point of total light transmittance, and also has both sheet transportability, mold release from heat-pressed mold, heat resistance, bendability and wear resistance. An excellent effect of providing a marking multilayer sheet is achieved. In particular, it is excellent in preventing tampering and preventing counterfeiting.

BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic diagram which shows one Embodiment of the laser marking multilayer sheet | seat of this invention, Comprising: The transparent laser marking sheet A is a transparent laser marking sheet which consists of a single layer, Comprising: The figure which showed the cross section of the laser marking multilayer sheet typically It is. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing an embodiment of a laser marking multilayer sheet according to the present invention, wherein the transparent laser marking sheet A is a transparent laser marking sheet composed of three layers, and schematically shows a cross section of the laser marking multilayer sheet. It is. It is a schematic diagram which shows an example in the case of using the laser marking multilayer sheet of this invention for an electronic passport. It is a schematic diagram which shows an example in the case of using the laser marking multilayer sheet of this invention for a plastic IC card. It is a schematic diagram which shows an example in the case of using the laser marking multilayer sheet of this invention for a plastic IC card.

  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.

[1-1] Laser marking multilayer sheet of the present invention:
As shown in FIG. 1A, the laser marking multilayer sheet 1A of the first invention is a laser marking multilayer sheet 1A formed by laminating a transparent laser marking sheet A (reference numeral 3) and a multilayer sheet B (reference numeral 5). The transparent laser marking sheet A (reference numeral 3) is a transparent laser marking sheet formed by melt extrusion molding, and is a laser light energy absorbing material with respect to 100 parts by mass of a transparent resin mainly composed of a polycarbonate resin. Is made of a transparent polycarbonate resin composition containing 0.0005 to 1 part by mass, and the transparent laser marking sheet A is made of a transparent sheet having a total thickness of 50 to 200 μm. The multilayer sheet B (reference numeral 5) is a skin. Layer (symbol 5a) and core layer (symbol 5b), and less by melt extrusion Both are multilayer sheets formed by laminating three sheets, and the skin layer (symbol 5a), which is the outermost layer of the multilayer sheet B (symbol 5), is a dicarboxylic acid mainly composed of terephthalic acid units. A polyester comprising a glycol unit mainly comprising a unit, an ethylene glycol unit (I), and a 1,4-cyclohexanedimethanol unit (II), and the ethylene glycol unit (I) and 1,4-cyclohexanedi The methanol unit (II) is a copolymer polyester resin in which (I) / (II) = 90-30 / 10-70 mol%, and the core layer (reference numeral 5b) of the multilayer sheet B (reference numeral 5) Is made of a transparent resin mainly composed of a polycarbonate resin, and the skin layer (reference numeral 5a) and / or the core layer (reference numeral 5b) of the multilayer sheet B has the above-mentioned 1 part by mass or more of at least one kind of resin colorant such as dye or pigment is added to 100 parts by mass of the copolyester resin and / or 100 parts by mass of the polycarbonate resin. A laser comprising a colored multilayer sheet having a total thickness of 100 to 300 μm and a thickness ratio of the core layer to the total thickness of the multilayer sheet B of 30% or more and less than 85% It is configured as a marking multilayer sheet 1A.

[1-2] Laser marking multilayer sheet of the present invention:
Further, as shown in FIG. 1B, the laser marking multilayer sheet of the second invention is a laser marking multilayer sheet obtained by laminating a transparent laser marking sheet A (reference numeral 3) and a multilayer sheet B (reference numeral 5). . The transparent laser marking sheet A (reference numeral 3) has a skin layer (reference numeral 3a) and a core layer (reference numeral 3b), and is a transparent laser marking sheet formed by melt extrusion molding, wherein the skin layer (reference numeral 3a) ) Is made of a transparent resin mainly composed of a polycarbonate resin, and the core layer (reference numeral 3b) is composed of 0.0005 to 1 of a laser light energy absorbing material with respect to 100 parts by mass of the transparent resin mainly composed of the polycarbonate resin. It consists of transparent polycarbonate resin composition containing a mass part, and the total thickness of the said transparent laser marking sheet A consists of 50-200 micrometers, and the thickness which occupies with respect to the total thickness of the said transparent laser marking sheet A of the said core layer The multilayer sheet B is composed of a multilayer sheet having a ratio of 20% to less than 90%. a) and a core layer (reference numeral 5b), a multi-layer sheet formed from a sheet of at least three layers to be laminated. The skin layer (symbol 5a) which is both outermost layers of the multilayer sheet B (symbol 5) is composed of a dicarboxylic acid unit mainly composed of terephthalic acid units, an ethylene glycol unit (I), and 1,4-cyclohexanedimethanol. The polyester is composed of glycol units mainly composed of the unit (II), and the ethylene glycol unit (I) and the 1,4-cyclohexanedimethanol unit (II) are (I) / (II) = 90 to The multilayer sheet B is made of a copolymerized polyester resin of 30/10 to 70 mol%, and the core layer (reference numeral 5b) of the multilayer sheet B (reference numeral 5) is made of a transparent resin mainly composed of a polycarbonate resin. In the skin layer (reference 5a) and / or the core layer (reference 5b), 100 parts by mass of the copolyester resin and / or the polycarbonate 1 part by mass or more of a colorant of a resin such as a dye or a pigment is contained with respect to 100 parts by mass of the resin, and the total thickness of the multilayer sheet B is 100 to 300 μm. At the same time, the thickness ratio of the core layer to the total thickness of the multilayer sheet B is configured as a laser marking multilayer sheet 1B composed of a colored multilayer sheet of 30% or more and less than 85%.

[A] Configuration of transparent laser marking sheet A:
The transparent laser marking sheet A of the present invention is configured as a sheet having a single layer structure, and when it is a sheet having a single layer structure, it is preferably formed by a melt extrusion molding.

  Further, when the transparent laser marking sheet A is configured as a sheet having a single layer structure, the transparent laser marking sheet A is formed from a polycarbonate resin (PC), particularly 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 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. Thus, by forming the transparent laser marking sheet A from a transparent resin layer mainly composed of polycarbonate resin (PC), the so-called “fluff” due to the foaming of the marking portion by laser light irradiation is suppressed and the laser light irradiation is performed. The wear resistance of the marking portion can be improved.

  In addition, when the transparent laser marking sheet A is configured as a sheet having a single layer structure, it is important that the transparent laser marking sheet A has high transparency, such as a resin or filler that does not hinder the transparency of the polycarbonate resin. Although there is no particular limitation, for the purpose of improving scratch resistance or heat resistance, 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.

  More preferably, the transparent laser marking sheet A is configured as a 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 sheet having a three-layer structure. In other words, in the transparent laser marking sheet A, “three-layer sheet” is for convenience of explanation, and “three-layer sheet” means “a sheet composed of at least three layers”. This means that it is not intended to limit the sheet to “three layers”. That is, if it is composed of 3 or more layers, it is included in the transparent laser marking sheet A, whether it is composed of 5 layers, 7 layers, or an odd number of layers. .

  Further, when the transparent laser marking sheet A is configured as a “at least three-layer” structure composed of a skin layer and a core layer, it is laminated by melt coextrusion molding (coextrusion method).

  When the transparent laser marking sheet A is composed of the above-described “at least three layers” multilayer structure, the skin layer of the transparent laser marking sheet A described later is the outermost position of the sheet composed of the multilayer structure. It is necessary to be disposed on both sides of the sheet and further so that the core layer is sandwiched between the skin layers (between). The thickness of the transparent laser marking sheet A skin layer is not particularly limited, but it is more preferable that the transparent laser marking sheet A is formed to have a thickness within a predetermined range described later.

  However, even when the transparent laser marking sheet A is composed of the above-mentioned “odd-numbered odd number layers” or more, if it has a multi-layer structure, the layers per layer of the skin layer and the core layer to be arranged If the thickness is too thin, a so-called mold stick may be generated in the heating press process during lamination. Accordingly, a multilayer sheet composed of 5 layers is more preferable, and a 3-layer structure is more preferable.

  That is, the transparent laser marking sheet A in the present embodiment is composed of odd layers as described above because a multilayer sheet composed of even layers always has the same structure as a multilayer sheet composed of odd layers. For example, a transparent laser marking sheet consisting of four layers has a layer arrangement of skin layer (PC) / core layer (PC) / core layer (PC) / skin layer (PC), and eventually consists of an odd number of layers. It is because it becomes the structure similar to the transparent laser marking sheet made.

  For example, in the case of the transparent laser marking sheet A composed of three layers (so-called “three-layer sheet”), an arrangement of layers such as skin layer (PC) / core layer (PC) / skin layer (PC) is made. As described above, two skin layers are disposed on the outermost sides of one and the other, and one core layer is disposed 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 arranged on the outermost sides of one and the other, and the skin layer and the core layer may be alternately arranged to form the transparent laser marking sheet A. Here, as described above, even if constituted as a single-layer transparent laser marking sheet having only the core layer, it has sufficient laser colorability and can exert the effects of the present application. The transparent laser marking sheet A having such a multilayer structure is formed. By constructing the transparent laser marking sheet A in such a multilayer structure, it is possible to irradiate laser light at a higher power than the single-layer transparent laser marking sheet only of the core layer, and to increase the concentration of the laser marking part, In addition, this is because so-called “swelling” due to foaming of the core layer marking portion can be suppressed and surface smoothness can be maintained. In addition, since the skin layer is laminated on the upper layer of the core layer marking portion, a synergistic effect that the wear resistance of the marking portion is further improved as compared with the case without the skin layer can be achieved.

  In addition, the total thickness (total thickness) of the transparent laser marking sheet A is preferably 50 to 200 μm in either a single layer or a three-layer sheet. If the total thickness of the transparent laser marking sheet A is less than 50 μm, the laser marking property becomes insufficient, which is not preferable. Further, when the total thickness of the transparent laser marking sheet A exceeds 200 μm, for example, using a laser marking multilayer sheet composed of the transparent laser marking sheet A and the multilayer sheet B exceeding 200 μm, a multilayer sheet for electronic passports and When a plastic card is multilayered and molded, the total maximum thickness of 800 μm, which is the thickness standard, may be exceeded.

  Further, when the transparent laser marking sheet A is a multilayer sheet (so-called three-layer sheet) composed of a skin layer and a core layer, the total thickness (total thickness) of the transparent laser marking sheet A is 50 to 200 μm. The ratio of the thickness of the core layer to the total sheet thickness of the multilayer sheet is preferably 20% or more and less than 90%. If the thickness of the core layer is less than 20%, the laser marking property is inferior, which is not preferable. In addition, at 90% or more, when the skin layer becomes too thin and laser light is irradiated with high power, the laser light energy absorbent blended in the core layer absorbs the laser light energy and converts it into heat, High heat is generated, and the effect of suppressing the so-called “fluff generation” in the laser beam irradiation portion is poor, which is not preferable. Even if the laser beam energy is adjusted to obtain a preferable laser color, the abrasion resistance of the laser marking part is sufficient compared to the skin layer thickness within the above-mentioned desired range. Not preferable.

  Thus, it becomes easy to draw local characteristics such as the characteristics of the transparent laser marking sheet A by setting the total thickness of the transparent laser marking sheet A composed of a single layer sheet or a three layer sheet to a desired thickness. 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.

  Moreover, it is preferable that the total light transmittance of the said transparent laser marking sheet A is 70% or more, More preferably, the total light transmittance of the transparent laser marking sheet A is 85% or more. For example, when the 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 for those uses. Therefore, for example, a white sheet on which characters, figures, etc. are printed (hereinafter, a white sheet on which letters, figures, etc. are printed is appropriately printed on the lower part of the transparent laser marking multilayer sheet of the present embodiment. )), Etc., the non-printing part of the transparent laser marking sheet A which is the outermost layer is irradiated with laser light to develop a black color, marking images and characters, and design and laser in the printing part It is often used in combination with anti-counterfeiting by marking. By manufacturing and using in this way, a clear image can be obtained by virtue of the sharpness of the printed portion and the black / white contrast of the laser marking portion because the underlayer is white. 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. (The sharpness of black / white contrast can be emphasized.) In other words, the transparency of the outermost layer is important for ensuring the sharpness of the printed part and the black / white contrast of the laser marking part. If the total light transmittance is less than 70%, the black / white contrast is insufficient, and there is a problem that sufficient marking properties cannot be ensured, and the printing is performed on the base white sheet. This is not preferable because it causes problems.

  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] Skin layer in transparent laser marking sheet A:
When the skin layer is formed on the transparent laser marking sheet A, that is, when it is composed of a multilayer structure as a “three-layer structure”, the skin layer is configured as both outermost layers arranged outside the three-layer sheet. Is done. 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.

  Here, the thicknesses of the skin layers are preferably the same. When the transparent laser marking sheet A is constructed as a multilayer sheet from skin layers having different thicknesses, it is common to perform laser marking from the front and back in a multilayer laminate for electronic passports and cards. Because the thickness of the outermost skin layer and the outermost skin layer is different, the so-called “swelling” suppression effect and the abrasion resistance effect of the marking part due to the foaming of the core layer marking by laser light irradiation are not preferable. It is. Further, for example, when the transparent laser marking sheet A is configured as a multilayer sheet from three layers of skin layer (PC) / core layer (PC) / skin layer (PC), the thickness of the core layer is 20%. When the content is less than 90%, the skin layer is 10% or more and less than 80% on both sides. When the thickness of the skin layer is less than 10%, 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-2] Core layer in transparent laser marking sheet A:
As described above, the core layer is a so-called core layer that is arranged at the center of the three-layer sheet when the transparent laser marking sheet A is composed of the three-layer sheet and the skin layer is formed on the outermost layer. Composed. That is, in the case of a three-layer sheet, the core layer is formed as a core layer of the three-layer sheet so as to be sandwiched between two skin layers disposed on the outermost side. The thickness of the core layer is preferably formed so that the ratio of the thickness in the entire sheet is 20% or more and less than 90%. More preferably, it is 40% or more and less than 85%. 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 90%, the so-called “swelling” suppression effect 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. . Moreover, if the thickness ratio of the core layer is less than 20%, the laser marking property is inferior, which is not preferable.

  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-3] Laser light energy absorbing material:
When the transparent laser marking sheet A has a single layer structure, the transparent laser marking sheet A, or when the transparent laser marking sheet A is at least a three-layer sheet, a polycarbonate resin is used for the core layer. It is desirable that 0.0005 to 1 part by mass of the laser light energy absorbing material is contained with respect to 100 parts by mass of the transparent resin as a main component. 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. 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 decrease or large irregularities may occur on the sheet surface, which 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, vanadium, bismuth, 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.

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

  The addition amount (mixing amount) of the energy absorber is desirably 0.0005 to 1 part by mass (mixing) of carbon black, and preferably 0.0008 to 0.1 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 0.0005 to 1 part by mass Preferably, the amount is 0.0008 to 0.5 parts by mass.

  Thus, the addition amount (blending amount) of the energy absorber is adjusted to a desired amount because the transparent laser marking sheet A is preferably transparent. In other words, when used for electronic passport laminate sheets and plastic card laminates, a transparent laser marking sheet (layer called overlay) is laminated on a printed white sheet (layer called inlay). It is used for example, but the laser beam is irradiated to the overlay of the part where the printing part is not applied, black color is developed, the image and characters are marked, and the forgery prevention effect by the printing part and laser marking Often used in combination. By manufacturing and using in this way, a clear image can be obtained by virtue of the sharpness of the printed portion and the black / white contrast of the laser marking portion because the underlayer is white. In other words, if the overlay layer laminated on the above inlay layer is inferior in transparency, the printed image, characters, etc. will be unclear, and the black / white contrast in the laser marking part will be inferior. It becomes an upper problem. For this purpose, carbon black having a small average particle diameter is preferably used, and a mixture of carbon black and at least one selected from other metal oxides, metal sulfides, metal carbonates and metal silicates is used as laser energy. Also when used as an absorbent, the average particle size of these metal oxides and metal sulfides 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 sheet A is not preferable. 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-4] Lubricant, antioxidant and / or anti-coloring agent:
In the present embodiment, the transparent laser marking sheet A preferably contains a lubricant. When the transparent laser marking sheet A is a so-called three-layer sheet, the skin layer preferably contains 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 transparent laser marking sheet A contains an antioxidant and / or an anti-coloring agent, and an ultraviolet absorber and / or a light stabilizer as necessary. Is made of a so-called three-layer sheet, the skin layer and / or the core layer may contain an antioxidant and / or an anti-coloring agent, and an ultraviolet absorber and / or a light stabilizer, if necessary. preferable. 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. In addition, the addition (formulation) of UV absorbers and / or light stabilizers effectively acts to suppress the light deterioration resistance during storage of the transparent laser marking sheet A and the actual use of the electronic passport or plastic card as the final product. To do.

  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, if the transparent laser marking sheet A is a single layer, the transparent laser marking sheet A comprises 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. It consists of a transparent polycarbonate resin composition, and furthermore, the transparent laser marking sheet A is 0.1 to 5 parts by mass of an antioxidant and / or an anti-coloring agent with respect to 100 parts by mass of a transparent resin whose main component is a polycarbonate resin, and If the transparent laser marking sheet A is a multilayer (so-called “three-layer sheet”) containing 0.1 to 5 parts by weight of an ultraviolet absorber and / or light stabilizer, the skin (of the transparent laser marking sheet A) The layer contains 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. It consists of a transparent polycarbonate resin composition, and further, an antioxidant and / or an anti-coloring agent for 100 parts by mass of the transparent resin whose skin layer and / or core layer (of the transparent laser marking sheet A) is mainly composed of a polycarbonate resin. 0.1 to 5 parts by mass of the agent, and 0.1 to 5 parts by mass of the ultraviolet absorber and / or the 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. Furthermore, when the antioxidant and / or anti-coloring agent is less than 0.1 parts by mass, there is a tendency to cause problems such as a thermal oxidation reaction of the polycarbonate resin in the process of melting, extruding and molding, and thermal discoloration resulting therefrom. Exceeding the part is not preferable because defects such as bleeding of these additives are likely to occur. 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.

  Further, a transparent laser marking sheet A including a so-called single layer structure and a multilayer structure (the above-mentioned three-layer sheet) and / or a core layer and / or a skin layer of a multilayer sheet B (described later) is 100 parts by mass of a thermoplastic resin. On the other hand, it is also one of preferable modes to contain 0.1 to 5 parts by mass of an antioxidant and / or a coloring inhibitor and 0.1 to 5 parts by mass of an ultraviolet absorber and / or a light stabilizer. In addition to being able to contain a desired amount of an antioxidant and / or an anti-coloring agent, and an ultraviolet absorber and / or a light stabilizer as appropriate, the region to be contained can be selected as appropriate. This is because the effects of the present application can be achieved more synergistically.

[A-5] Matting:
Moreover, it is preferable that mat processing is given to both surfaces of the transparent laser marking sheet A, and average roughness (Ra) is 0.1-5 micrometers. Thus, the reason for forming the mat processing on the surface of the transparent laser marking sheet A is, for example, that the configuration of the laser marking multilayer sheet of this embodiment is the same as the transparent laser marking sheet A of this embodiment / another multilayer sheet B. When the hot press molding is performed, air between the transparent laser marking sheet A of the present embodiment and another multilayer sheet B easily escapes, and when these sheets are transported to the lamination process, they are transported by suction and adsorption. Then, after aligning and laminating these multilayer sheets, when removing the multilayer sheets by injecting air, it is difficult to desorb if they are not matted, or the laminating position may be shifted even if they can be desorbed Problems tend to occur. 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.

[B] Configuration of multilayer sheet B:
The multilayer sheet B of the present invention is configured as a sheet having at least a three-layer structure composed of a skin layer and a core layer, and is laminated by melt extrusion 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 multilayer sheet B in the present embodiment, “three-layer sheet” is for convenience of description, and “three-layer sheet” means “a sheet composed of at least three layers”. This is not intended to limit the sheet to “three layers”. In other words, the multilayer sheet B of the present embodiment may be composed of 5 layers, 7 layers, or an odd number of layers. include.

  However, even when the multilayer sheet B 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 both sides of the sheet Furthermore, it is necessary that the core layer is disposed 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 B is composed of the above-mentioned “odd-numbered odd number layers” or more, if the multilayer sheet B is too multilayered, the layer thickness per layer of the skin layer and the core layer to be arranged is If it becomes too thin, the problem of poor heat fusion with the transparent laser marking sheet A occurs. Therefore, it is preferably composed of 5 layers, more preferably 3 layers.

  Here, the multilayer sheet B is composed of odd layers as described above because 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 such as skin layer (PETG) / core layer (PC) / core layer (PC) / skin layer (PETG). 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 (PETG) / core layer (PC) / skin layer (PETG). 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 (PETG) / core layer (PC) / skin layer (PETG) / core layer (PC) / skin layer (PETG) As is done, two skin layers may be arranged on the outermost sides of one and the other, and a multilayer sheet may be formed by alternately arranging the skin layers and the core layer. By forming a multilayer sheet having a multilayer structure in this manner, sufficient heat-fusibility can be ensured.

  Further, the total thickness (total thickness) of the three-layer sheet (multilayer sheet B) is 100 to 300 μm in total thickness, and the ratio of the thickness of the core layer to the total thickness is 30%. As mentioned above, it is desirable to consist of less than 85%. If the total thickness of the three-layer sheet (multilayer sheet B) is less than 100 μm, the PETG layer, which is the skin layer of the multilayer sheet B, is inevitably thinned and is laminated on the outermost layer during heat fusion in the multilayer sheet lamination process. The heat-sealing property between the transparent laser marking sheet A (including both “single layer sheet” and so-called “three layer sheet”) and the multilayer sheet B cannot be ensured. When the thickness exceeds 300 μm, if a multilayer sheet for electronic passport is molded using a three-layer sheet exceeding 300 μm, the total thickness becomes too thick to be used. Since the thickness exceeds the maximum thickness of 800μm, which is the standard for general contact and non-contact cards, it is not preferred because it is not versatile and difficult to use. Furthermore, it is desirable that the ratio of the thickness of the core layer to the total thickness of the multilayer sheet B is 30% or more and less than 85%. The heat-sealing property between the transparent laser marking sheet A (including both “single-layer sheet” and so-called “three-layer sheet”) laminated on the outermost layer and the multilayer sheet B at the time of heat-sealing in the sheet lamination step cannot be ensured. On the other hand, if the thickness of the skin layer is too large, the thickness of the core layer, which will be described later, will inevitably become thin, and if the colorant is blended only in the core layer, the colorant only in one extruder. Since it is only necessary to add a resin containing, if washing is extremely difficult compared to the case where a colorant is blended in the skin layer and the core layer, it is only half the labor, but when the partial or entire surface is printed on the multilayer sheet B The incompatibility is In addition, when a coloring agent is blended in the skin layer and the core layer, the above-mentioned problem of the incompatibility does not occur, but, for example, two extruders are used for co-extrusion of a three-layer sheet with two kinds of resins. However, since these two extruders are charged with a resin containing a colorant, the cleanup after the production of the two-kind, three-layer coextruded sheet takes a considerable amount of time to clean the colorant, Therefore, the total thickness (total thickness) of the three-layer sheet (multilayer sheet B) and the thickness of the core layer with respect to the total thickness are within the desired range as described above. It is desirable that a ratio of

  Thus, by setting the thickness of the entire three-layer sheet to a desired thickness, not only the local characteristics such as the characteristics of the multilayer sheet B can be easily extracted, but also the laser marking multilayer sheet of this embodiment (transparent laser marking sheet) It becomes easy to draw out the characteristics of this embodiment as a whole (multilayer sheet consisting of A and multilayer sheet B). 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 in view of the effects of the present application, such as easier to improve the contrast, in combination with making the thickness of the entire sheet within the desired range.

  It should be noted that the adhesiveness and imperviousness of the multilayer sheet, and the contrast with the laser marking part (of the transparent laser marking sheet A) are extremely important, such as whether the multilayer sheet can be put into practical use, productivity, and market needs. Since it becomes an element, the relationship between the total thickness of the entire three-layer sheet and the thicknesses of the skin layer and the core layer will be described in detail later.

[B-1] Skin layer in multilayer sheet B:
The skin layer in the multilayer sheet B is configured as both outermost layers arranged 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 surfaces (outside) of the core layer in the multilayer sheet B described later.

  The thicknesses of the skin layers are preferably the same. Constructing the multilayer sheet B from skin layers having different thicknesses is not preferable because it causes variations in the heat-sealing property between the outermost transparent laser marking multilayer sheet and the multilayer sheet B at the time of heat-sealing in the multilayer sheet laminating process. In addition, it is not preferable because a warp may occur in the laminated body after the hot pressing. In addition, for example, when the multilayer sheet B is composed of three layers of skin layer (PETG) / core layer (PC) / skin layer (PETG), the thickness of the core layer is 30% or more and less than 85%. In this case, the skin layer is 15% or more and less than 70% on both sides. If the thickness of the skin layer is too thin, the heat-fusibility will be deteriorated. On the other hand, if the thickness of the skin layer is too large, the thickness of the core layer described later will inevitably become thin. In other words, if the colorant is blended only in the core layer, it is only necessary to put the resin containing the colorant into only one extruder, so cleaning is extremely more than when the colorant is blended in the skin layer and the core layer. In other words, half the labor is required, but the incompatibility when partially or fully printed on the multilayer sheet B is insufficient. In addition, when a coloring agent is blended in the skin layer and the core layer, the above-described problem of incompatibility does not occur. For example, two extruders are used for co-extrusion of a three-layer sheet using two kinds of resins. The two extruders will be charged with a resin containing a colorant, and the cleanup after the production of the two-type, three-layer coextruded sheet takes a lot of labor to clean the colorant, which is both productive and costly. Problems are likely to occur. Therefore, it is desirable to form the total thickness (total thickness) of the three-layer sheet (multilayer sheet B) and the ratio of the thickness of the core layer to the total thickness within the desired range as described above. .

  As a material for forming the skin layer, a polyester-based resin composition, that is, a substantially non-crystalline aromatic polyester described later prepared by a copolymer polyester resin described later (see [B-1-1]) is prepared. It forms as a layer which consists of a resin composition.

[B-1-1] Copolyester resin:
The copolyester resin used in the present embodiment is blended as a main component of the amorphous aromatic polyester resin composition. As the copolymer polyester resin, the skin layer has a dicarboxylic acid unit mainly composed of terephthalic acid units and an ethylene glycol unit (I) [hereinafter referred to as “ethylene glycol unit (I)”], and 1,4-cyclohexane. It is a polyester composed of glycol units mainly composed of dimethanol units (II), and ethylene glycol units (I) and 1,4-cyclohexanedimethanol units (II) are (I) / (II) = A copolyester resin of 90-30 / 10 to 70 mol% is used. The reason for preparing the component amounts of ethylene glycol and 1,4-cyclohexanedimethanol contained in this copolymerized polyester resin is that the amount of substitution of the ethylene glycol component in the copolymerized polyester resin is less than 10 mol%. This is because the obtained resin does not become sufficiently amorphous, and recrystallization proceeds in the cooling step after heat fusion, resulting in poor heat fusion. Moreover, it is because the resin obtained exceeding 70 mol% is not sufficiently amorphous, and recrystallization proceeds in the cooling step after heat fusion, resulting in poor heat fusion. Therefore, as in this embodiment, the resin obtained by adjusting the component amounts of ethylene glycol and 1,4-cyclohexanedimethanol becomes sufficiently amorphous, and is excellent in terms of heat fusibility. Therefore, it can be said to be a desirable resin.

  Furthermore, as this copolyester resin, for example, a substantially non-crystalline aromatic polyester-based resin (trade name “trade name”) in which about 30 mol% of the ethylene glycol component in polyethylene terephthalate is substituted with 1,4-cyclohexanedimethanol. PETG "(manufactured by Eastman Chemical Co., Ltd.) is commercially available.

[B-2] Core layer in multilayer sheet B:
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 preferably formed so that the ratio of the thickness in the entire sheet is 30% or more and less than 85%. Preferable is 40% or more and less than 80%. When the thickness ratio of the core layer is 85% or more, since the total thickness of the multilayer sheet B is as thin as 100 to 300 μm, the skin layer is relatively thin, and is the outermost layer at the time of heat-sealing in the multilayer sheet laminating process. Transparent laser marking sheet A (including both “single-layer sheet” and so-called “three-layer sheet”) is not preferable because it causes variations in heat-fusability between the multilayer sheet B. The thickness ratio of the core layer is 30%. If less, the thickness of the core layer will inevitably become thin, and if a colorant is blended only in the core layer, the resin containing the colorant need only be introduced into one extruder, so the skin layer If it is extremely clean compared with the case where a colorant is added to the core layer, it takes half the labor, but the incompatibility when partially or fully printed on the multilayer sheet B is insufficient. When a colorant is blended in the layer, the above-mentioned problem of incompatibility does not occur. For example, two extruders are used for co-extrusion of a three-layer sheet with two kinds of resins. In this case, a resin containing a colorant is added, and the cleanup after the production of the two-kind / three-layer coextruded sheet takes a considerable amount of time to wash the colorant, and thus tends to cause productivity and cost problems. It is desirable that the total thickness (total thickness) of the three-layer sheet (multilayer sheet B) and the ratio of the thickness of the core layer to the total thickness be formed within the desired range as described above.

  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.

[B-2-1] Coloring agents for resins such as dyes and pigments:
The multilayer sheet B is a colored multilayer sheet, and the skin layer and / or the core layer of the multilayer sheet B are dyes, pigments, etc. with respect to 100 parts by mass of the copolyester resin and / or 100 parts by mass of the polycarbonate resin. It is desirable to contain 1 part by mass or more of at least one colorant of the resin. This is different from the transparent laser marking sheet A. In this way, 1 part by mass or more of the colorant of the resin such as a coloring dye or a pigment is blended after laminating the laminate sheet of the transparent laser marking sheet A and the colored multilayer sheet B as described later. This is because the contrast is good when marking is performed by irradiating the film, and the incompatibility when printing on the colored multilayer sheet B is ensured.

  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.

  More preferably, a resin colorant such as a white dye or a pigment, which is conspicuous in contrast, is added.

[B-3] Matting:
The mat processing in the multilayer sheet B is the same as that of the transparent laser marking sheet A. Therefore, see the description of the transparent laser marking sheet A.

[C] Relationship between transparent laser marking sheet A and multilayer sheet B:
As described above, by laminating the transparent laser marking sheet A and the multilayer sheet B, the effects of the present application can be achieved. That is, the transparent laser marking sheet A is configured as a transparent laser mark three-layer sheet made of PC (laser mark) transparent single layer sheet or PC / PC (laser mark) / PC. Further, a colored multilayer sheet B made of PETG / PC (containing white colorant) / PETG is laminated on the surface of the transparent laser marking sheet A opposite to the surface to be irradiated with a laser, whereby an upper layer (transparent laser) This is to ensure the contrast when the marking layer A) is irradiated with laser and the core layer PC is black, and to show the visibility and clarity of the marking portion. Furthermore, images, characters, etc. on the colored multilayer sheet B Since printing is generally done, the printed part is sharp and the printed part is protected.In other words, when printing is performed on the outermost layer, the printed part is polished when some friction or wear occurs. It is important to be able to solve this problem by printing on the surface of the multilayer sheet B, which is the lower layer of the transparent laser marking sheet A. A.

  In the above description, the laser marking multilayer sheet in the embodiment is described as an arrangement pattern in which the multilayer sheet B is laminated on the lower layer of the transparent laser marking sheet A. However, the arrangement is not limited to such an arrangement. That is, the transparent laser marking sheet A is not necessarily disposed in the upper layer, and the multilayer sheet B is disposed in the lower layer. For example, the transparent laser marking sheet A may be disposed in the lower layer, and the multilayer sheet B may be disposed in the upper layer. As described above, the transparent laser marking sheet A (or the multilayer sheet B) may be disposed in the upper layer or the lower layer because the position (direction) for viewing the laser-marked image or the like is not limited to the vertical direction. It is. In other words, for example, in the case of using the laser marking multilayer sheet in the present embodiment in a booklet form like a passport, the transparent laser marking sheet A is disposed on the upper layer when viewed in a plan view and viewed from above. Even when the multilayer sheet B is arranged in the lower layer, when the next page is opened and viewed in plan, the arrangement position of the transparent laser marking sheet A and the multilayer sheet B is exactly the same as that in which the multilayer sheet B is arranged in the upper layer. This is because the transparent laser marking sheet A is disposed. Therefore, the upper layer and the lower layer here are used for convenience of explanation, and mean that the transparent laser marking sheet A is arranged on the laser irradiation side. By being arranged in this way, the clear laser marking sheet A and the multilayer sheet B after laser marking can obtain clear images such as images and high contrast, and the effects of the present application can be achieved.

  Furthermore, the laser marking multilayer sheet in the present embodiment is not limited to being laminated with the transparent laser marking sheet A / multilayer sheet B. For example, after performing various printing on the surface of the multilayer sheet B, the transparent laser marking sheet A / (printed) multilayer sheet B / other sheets or mesh cloth such as polyester / (printed) multilayer sheet B / transparent laser marking sheet A, when laminated with transparent laser marking sheet A / multilayer sheet B / other When laminating with a sheet or a mesh cloth such as polyester / multilayer sheet B / transparent laser marking sheet A, a multilayer sheet B / other sheet or a laminate sheet of mesh cloth / multilayer sheet B such as polyester is heat-sealed, After printing on the surface of this laminate sheet, Also it included widely such case of stacked laser marking sheet A / the laminate sheet / transparent laser marking sheet A. It becomes possible to respond flexibly according to the purpose of use and method of use, and the effects of the present application can be achieved. The above-mentioned “other sheets” include thermoplastic resin sheets used in plastic cards such as PET, PETG, heat-resistant PETG (PC / PETG alloy), PVC, PC, and PET, nylon, thermoplastic urethane (TPU). ) And the like, and can be used as an electronic passport hinge (a tail sheet, a so-called electronic passport cover, a thermoplastic resin sheet to be bound or adhered to the back cover). However, the present invention is not limited to these, and any of the above-described “other sheets” may be used as long as the configuration of the present application is employed and the effects of the present application are achieved.

[2] Application:
Moreover, the laser marking multilayer sheet in the present embodiment can be suitably used for electronic passports and plastic cards.

  For example, when used for an electronic passport, a polyester resin film, a thermoplastic urethane resin film, or a nylon resin for preparing two laser marking multilayer sheets in the present embodiment and facilitating binding of the laser marking multilayer sheets between them. A so-called laminating film made of one kind of film or one kind of cloth selected from polyester cloth and nylon cloth is arranged to form a sewing binding portion or the like as required, and further shown in FIG. As described above, an electronic passport may be created by arranging a cover sheet 9, a laminate 11, a visa sheet 13, an IC chip 15 and the like using the present embodiment. However, this is an example, and the present invention is not necessarily limited to such a configuration.

  Further, for example, when the transparent laser marking multilayer sheet in the present embodiment is used as a plastic IC card, a plastic IC card as shown in FIGS. 3A and 3B can be cited as an example. Specifically, as shown in FIGS. 3A and 3B, an IC-chiP • Antenna layer 21 as an inlet is used as a core of a plastic IC card, and on both sides of the IC-chiP • Antenna layer 21, Laminate laser marking multilayer sheets. That is, a colored multilayer sheet B (reference numeral 5, 5) is laminated as an inlay on both sides of the IC-chiP / Antenna layer 21, and an overlay is formed on both sides of the colored multilayer sheet B (reference numeral 5, 5) as an inlay. It is preferable to laminate a transparent laser marking sheet A (reference numerals 3 and 3) as a plastic IC card. When a non-contact IC card is formed in this way, when the laser beam 7 is irradiated, characters, figures, etc. can be clearly marked on the transparent laser marking sheet A as an overlay shown in FIGS. 3A and 3B. 3A shows a transparent laser marking sheet A as an overlay composed of a single layer, and FIG. 3B shows a transparent laser marking sheet A as an overlay composed of three layers, schematically showing a cross section. It is a figure.

[3] Method for forming transparent laser marking sheet A and multilayer sheet B:
In the present invention, in order to obtain the transparent laser marking sheet A and the colored multilayer sheet B, for example, a method in which each layer is formed into a film by melt extrusion molding in which the resin composition of each layer is coextruded and laminated, and this is laminated. There are a method of forming two layers by melt extrusion molding and laminating a film formed separately on the two layers, and it is preferable to laminate by melt extrusion molding from the viewpoint of productivity and cost.

  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 300 ° 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 transparent laser marking sheet A and the colored multilayer sheet B of the present invention are not limited to the above methods, and can be formed by a known method. For example, JP-A-10-71763 Nos. (6) to ( 7) It can be obtained according to the description on page.

  The transparent laser marking sheet A and the multilayer sheet B obtained as described above are cut into predetermined dimensions, stacked, and bonded by heat fusion or the like at a desired temperature for a desired time and at a desired temperature. A multilayer sheet can be obtained. Also, after extruding the transparent laser marking sheet A and the multilayer sheet B by melt coextrusion molding, each of the two types and the three-layer sheet is wound between the heated rollers heated to a predetermined temperature, After manufacturing a long laminate sheet by heating and pressing through a transparent laser marking sheet A / multilayer sheet B / transparent laser marking sheet A or multilayer sheet B / other sheet / multilayer sheet B with a heating roller It is good to manufacture by the method of cutting to the dimension of. Further, after the transparent laser marking sheet A and the multilayer sheet B are cut into predetermined dimensions, the above-mentioned, for example, transparent laser marking sheet A / multilayer sheet B / transparent laser marking sheet A, transparent laser marking are performed by a hot press machine. Sheet A / multilayer sheet B / other sheets or polyester mesh cloth / multilayer sheet B / transparent laser marking sheet A, or multilayer sheet B / other sheets / multilayer sheet B single-wafer laminate sheets can also be produced.

  Here, the desired time, the desired pressure, and the desired temperature are not particularly limited. The desired time, desired pressure, and desired temperature are preferably selected as appropriate. As a general example, the desired time is about 10 seconds to 6 minutes, the desired pressure is 1 to 20 Mpa, and the desired temperature is 120 to 180 ° C. as an example.

[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 transparent laser marking sheet A constituting the laser marking multilayer sheet is colored, and the transparent laser marking sheet A is mainly made of a polycarbonate resin having high heat resistance. Since it is a component, it is possible to irradiate a high-power laser beam, whereby an image or the like can be drawn easily and more clearly. Furthermore, the transparent laser marking sheet A is composed of three layers of PC / PC (laser coloring layer) / PC, and a PC transparent skin layer is provided on the PC laser coloring layer. Even under the condition that “blowing” phenomenon occurs on the sheet surface due to “foaming” by light irradiation, the “blowing” phenomenon is suppressed by the PC transparent skin layer effect, so that an image or the like can be drawn more clearly. This PC transparent skin layer effect is not limited to this. In the case of a single layer of the PC laser coloring layer, the marking portion of the sheet is directly scraped by friction with the outside, whereas a PC transparent skin layer is added. Even if the PC transparent skin layer is shaved, the laser marking part is not shaved, so it can be said that the abrasion resistance of the laser marking part is more excellent.

  Furthermore, since a sheet made of polycarbonate resin has high heat resistance, it is necessary to increase the heat-sealing temperature to 200 to 230 ° C. in the multilayer laminate of the resin sheet, which causes a problem in the productivity of the hot press process. On the other hand, it is common for plastic data sheets such as plastic cards and electronic passports to perform various types of printing on an intermediate layer called an inlay layer. When the heating and fusing temperature is set to a high temperature of 200 to 230 ° C. in the pressing step, printing is often “yake”, and printed characters and images may be discolored, which is not preferable.

  In order to solve this problem, the PETG / PC (colored) / PCG of the present invention is applied to the inlay which is the underlayer of the PC laser coloring layer transparent single layer sheet or PC / PC (laser coloring layer) / PC transparent three-layer sheet. By laminating the PETG colored three-layer sheet, the glass transition temperature of PETG is about 80 ° C. and about 60 to 70 ° C. lower than that of polycarbonate resin, so the heat fusion temperature is lowered to about 150 ° C. and about 50 ° C. Therefore, the printed characters and images of the printing layer have an effect of suppressing discoloration. Therefore, the laser marking multilayer sheet of the present embodiment is excellent in laser markability, and the surface layer, or the core layer of the surface layer, is colored black by laser light irradiation to mark images and characters, but because the underlying layer is white With black / white contrast, clear characters and images can be drawn.

More preferably, the laser marking multi-layer sheet is laser-marked by irradiating a laser beam from the transparent laser marking sheet A side laminated on the laser marking multi-layer sheet as shown in FIGS. 1A and 1B. It is to print. Thus, by irradiating a desired laser beam from the transparent laser marking (multilayer) sheet side of this embodiment, an image etc. can be drawn easily and clearly. Therefore, the laser marking multilayer sheet of this embodiment is excellent in laser marking properties and heat fusion properties, and also in the abrasion resistance of the marking portion.

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

[1] Transparency of the transparent laser marking sheet A:
The total light transmittance of the transparent laser marking sheet A was measured using a spectrophotometer (trade name “EY7000” manufactured by Macbeth Co.).
◎: 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 sheet was cut to 100 × 300 mm, it was transported by a sheet transporter, and when the sheet was placed on a predetermined position on a heating press machine die, the sheet transportability 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:
Using a vacuum press machine (manufactured by Nissei Plastic Industry), the laminated sheets are sandwiched between two chrome-plated steel plates, preheated at a press temperature of 100 ° C. for 2 minutes, and then 160 ° C. and an actual pressure of 12 kgf / cm ^{2 for} 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 sheet A and the multilayer sheet B, sandwiched between two chrome-plated steel sheets, and preheated for 2 minutes at a press temperature of 100 ° C. using a vacuum press machine (manufactured by Nissei Plastic Industries). , 160 ° C., and 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.
A: There is no peeling, and the heat fusion property is excellent. B: A very small part can be peeled, but the sheet breaks. (Material destruction), △: Can be peeled with a fairly strong force. X: The entire surface is peeled, xx: The surface is peeled off after heating or with a very 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, laser marking was performed at a laser irradiation speed of 400 mm / sec, and was determined as follows from the sharpness of the image and the surface state of the marking portion.
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,
X: Poor clarity or large swelling of laser light irradiation part.

[7] Contrast property:
After printing on the multilayer sheet B, the process steps [5] and [6] were performed, and the contrast between the image by laser marking and the image by printing was determined by visual evaluation.
○: There is no change in the sharpness and visibility of the image by laser marking and the image by printing,
Δ: The sharpness and visibility of the image by laser marking and the image by printing are lowered.
X: The sharpness and visibility of the image by laser marking and the image by printing deteriorate.

[8] Abrasion resistance of transparent laser marking multilayer sheet:
In [6], the transparent laser marking sheet (including a three-layer structure and a single-layer structure) and a core sheet heat-bonded laminate are used in [6] to improve the wear resistance of the black laser marking portion irradiated with laser light. A rubbing tester (manufactured by Imoto Seisakusho) was used 50 times (25 reciprocations) with # 00 steel wool (load 500 gr), and the state before and after the test was judged by visual evaluation.
◎: Marking part is not abnormal, there is no change in image clarity and visibility,
○: Marking part is scraped, but image clarity and visibility are good.
Δ: Sharpening of the marking part is progressing, and the sharpness and visibility of the image are reduced.
X: The marking portion is greatly scraped, and the sharpness and visibility of the image are remarkably lowered.

(Production Example 1) Transparent laser marking sheet A [1]:
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, average particle diameter 75 nm, DBP oil absorption 86 ml / 100 gr) is added to 0.0015 part by mass, and as a phenolic antioxidant, n-octadecyl-3- (3,5-di-t-butyl- 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 (quotient The name “Tinubin 327” (manufactured by Ciba Specialty Chemicals) is blended in 0.2 parts, and a transparent laser marking multilayer sheet A having three layers of skin layer / core layer / skin layer is formed by T-die melt extrusion molding. Obtained. 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 transparent laser marking sheet A [1] which consists of 3 layers by which the mat | matte process was given so that it might become 0.5-1.8 micrometers was obtained.

(Production Example 2) Transparent laser marking sheet A [2]:
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 A [2] consisting of three layers 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 A [3]:
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 A [3] consisting of three layers was obtained in the same manner as in Production Example 1, except that the layer thickness ratio was 10%.

(Production Example 4) Transparent laser marking sheet A [4]:
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) is mixed with 0.0015 parts by mass, and (n-octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate ("Irganox 1076") is used 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) Part, T-die melt extrusion molding yielded a transparent laser marking single-layer sheet F having a total sheet thickness of 100 μm, and an average surface roughness (Ra) on both sides of 0.5 to 1.8 μm. A transparent laser marking sheet A [4] composed of a single layer, which was matted so as to obtain, was obtained.

(Production Example 5) Transparent laser marking sheet A [5]:
As a skin layer, 100 parts by mass of amorphous polyester (trade name “Easter GN071” manufactured by Eastman Chemical Co., Ltd., EG / CHDM = 70/30 mol%) was mixed with 0.3 parts by mass of calcium stearate as a lubricant. Polycarbonate as the core layer (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 In addition to blending 0.0015 parts by mass of oil absorption 86 ml / 100 gr), (n-octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate (“ Irganox 1076 “Ciba Specialty Chemicals Co., Ltd.) 0.1 part, and 2- (2′-hydroxy-3 ′, 5′-di-t-butylphenyl) -5-chloro as an ultraviolet absorber Benzotriazole (trade name “Tinubin 327”, Ciba Specialty Chemi 0.2 parts), and a transparent laser marking multilayer sheet A having three layers of skin layer / core layer / skin layer was obtained by T-die melt extrusion molding, and the total thickness of the sheet was The thickness of the core layer is 100 μm, the thickness of the skin layers on the front and back is the same, and the layer structure is the skin layer (18 μm) / core layer (64 μm) / skin layer (18 μm). Furthermore, a transparent laser marking sheet A [5] consisting of three layers matted so as to have an average surface roughness (Ra) on both sides of 0.5 to 1.8 μm was obtained. Obtained.

(Production Example 6) Multilayer sheet B [1]:
Non-crystalline polyester (trade name “Easter GN071” manufactured by Eastman Chemical Co., Ltd., EG / CHDM = 70/30 mol%) as the skin layer, and polycarbonate (trade name “Taflon FN2500A”, manufactured by Idemitsu Kosan Co., Ltd., melt volume rate, as the core layer. = ^8cm 3 / 10min) with, and was blended with 0.3 part by weight of calcium stearate as a lubricant to the amorphous polyester. Furthermore, (n-octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate (“Irganox 1076”) manufactured by Ciba Specialty Chemicals Co., Ltd. is used as a phenolic antioxidant in the polycarbonate. ) As an ultraviolet absorber and 2- (2′-hydroxy-3 ′, 5′-di-t-butylphenyl) -5-chlorobenzotriazole (trade name “Tinuvin 327”, Ciba (Specialty Chemicals Co., Ltd.) 0.2 parts and titanium oxide 5 parts were blended, and a multilayer sheet B [1] of three layers of skin layer / core layer / skin layer was obtained by T-die melt extrusion molding. The total thickness of the sheet is 200 μm, the thickness of the skin layers on the front and back is the same, and the layer structure is skin layer (50 μm) / core layer (100 μm) / skim. The thickness of the core layer was 50% and the average surface roughness (Ra) on both sides was 0.5 to 1.8 μm. A multilayer sheet B [1] consisting of the applied three layers was obtained.

(Production Example 7) Multilayer sheet B [2]:
In the multilayer sheet B, the constitution of the layers is the skin layer (12 μm) / core layer (176 μm) / skin layer (12 μm), and the thickness of the core layer is 88% of the ratio as in Production Example 6. Thus, a multilayer sheet B [2] was obtained.

(Production Example 8) Multilayer sheet B [3]:
In the multilayer sheet B, the constitution of the layer is the skin layer (80 μm) / core layer (40 μm) / skin layer (80 μm), and the thickness of the core layer is 20%, the same as in Production Example 6 Thus, a multilayer sheet B [3] was obtained.

(Production Example 9) Multilayer sheet B [4]:
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, with blending titanium oxide 5 wt, phenolic antioxidants N-octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate (trade name “Irganox 1076”, manufactured by Ciba Specialty Chemicals)), and As a UV absorber, 2- (2′-hydroxy-3 ′, 5′-di-t-butylphenyl) -5-chlorobenzotriazole (trade name “Tinuvin 327”, manufactured by Ciba Specialty Chemicals) , 0.2 parts, skin layer / core layer / skin layer by T-die melt extrusion molding The multilayer sheet of the layer to obtain B [4]. The total thickness of the sheet is 200 μm, the thickness of the front and back skin layers is the same, the thickness of the front and back skin layers is the same, and the layer structure is skin layer (50 μm) / core layer (100 μm). ) / Skin layer (50 μm), and the thickness of the core layer was 50%.

  Various evaluations were performed on Examples 1 to 9 described above as Examples 1 to 3 and Comparative Examples 1 to 5 with the configurations shown in Table 1. The results are shown in Tables 1-2.

(Discussion)
As shown in Table 1, in Examples 1 to 3, all of the sheets were excellent in transparency, transportability, release property after laminating and heating press, and bubble release properties, and excellent laser marking properties and marking portions. It had wear resistance. All of them were excellent in sheet transportability, releasability after laminating and heating press, bubble release property and heat fusion property, and had excellent laser marking properties. In addition, compared with Examples 1 and 2, Example 3 is slightly inferior in wear resistance of the marking portion. However, when the product is in a usage environment such as hardware use, that is, the laser marking property is high. It was confirmed that there was no problem in use unless it was used in a field where quality and durability were strictly required.

  On the other hand, in Comparative Example 1, since the thickness ratio of the core layer of the transparent laser marking multilayer sheet A <3> was 10%, the laser marking property was inferior and the contrast property was also inferior. In Comparative Example 2, the non-crystalline polyester described above was used as the skin layer and the polycarbonate was used as the core layer, so that the sharpness was insufficient, or a slight bulge could be observed in the laser light irradiation part. The progress of shaving was observed, the sharpness and visibility of the image were lowered, and it was inferior to the examples. In Comparative Example 3, since the thickness of the core layer of the multilayer sheet B <2> was set to 88%, a problem occurred in terms of heat-fusibility and the contrast was inferior. In Comparative Example 4, since the thickness of the core layer of the multilayer sheet B <3> was set to 20%, the contrast could not be ensured, and the swelling of the laser light irradiation part was increased, resulting in a problem with the laser mark property. . In Comparative Example 5, since the polycarbonate layer is used as the skin layer of the multilayer sheet B <4>, and the polycarbonate layer is made of the polycarbonate containing titanium oxide or the like, the entire surface is peeled with a small force. It was difficult to put it into practical use. In Comparative Example 5, since the practical use was difficult when the entire surface was peeled, no other experiment was performed.

  The laser marking multilayer sheet of the present invention is excellent in laser marking properties, has a high contrast between the fabric color and the printed part, and provides clear characters, symbols and images, and heat fusion in the lamination process of the multilayer sheet. In addition, it has improved transparency from the point of total light transmittance, and also has sheet transportability, release from the mold after hot pressing, heat resistance, bendability, and wear resistance. It is an aligned laser marking multilayer sheet. In particular, it is excellent in preventing falsification and forgery and can be suitably used as a multilayer sheet for electronic passports or a plastic card.

1A, 1B: Laser marking multilayer sheet, 3: Transparent laser marking sheet A, 3a: Skin layer (of transparent laser marking sheet A), 3b: Core layer (of transparent laser marking sheet A), 5: Multilayer sheet B, 5a : Skin layer (of multilayer sheet B), 5b: core layer (of multilayer sheet B), 7: laser beam, 9: cover, 11: laminate, 13: visa sheet, 15: IC chip, 17: sewing binding part, 21 : IC-chiP / Antenna layer, 23: Plastic IC card.

Claims (10)

A laser marking multilayer sheet formed by laminating a transparent laser marking sheet A and a multilayer sheet B,
The transparent laser marking sheet A is a transparent laser marking sheet formed by melt extrusion molding, and 0.0005 to 1 of a laser light energy absorbing material with respect to 100 parts by mass of a transparent resin mainly composed of a polycarbonate resin. While comprising a transparent polycarbonate resin composition containing parts by mass,
The transparent laser marking sheet A consists of a transparent sheet having a total thickness of 50 to 200 μm,
The multilayer sheet B has a skin layer and a core layer, and is a multilayer sheet formed by laminating at least three sheets by melt extrusion molding,
The skin layers which are both outermost layers of the multilayer sheet B are mainly composed of dicarboxylic acid units mainly composed of terephthalic acid units, ethylene glycol units (I), and 1,4-cyclohexanedimethanol units (II). It is a polyester composed of glycol units, and the ethylene glycol unit (I) and the 1,4-cyclohexanedimethanol unit (II) are (I) / (II) = 90 to 30/10 to 70 mol%. Made of a copolyester resin,
The core layer of the multilayer sheet B is made of a transparent resin mainly composed of a polycarbonate resin,
For the skin layer and / or the core layer of the multilayer sheet B, at least one or more kinds of resin colorants such as dyes and pigments with respect to 100 parts by mass of the copolyester resin and / or 100 parts by mass of the polycarbonate resin. 1 part by mass or more,
Further, the total thickness of the multilayer sheet B is 100 to 300 μm, and the thickness ratio of the thickness of the core layer to the total thickness of the multilayer sheet B is 30% or more and less than 85%. Laser marking multilayer sheet consisting of colored multilayer sheets.   Furthermore, the transparent laser marking sheet A contains 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 is oxidized with respect to 100 parts by mass of the transparent resin. The laser marking multilayer according to claim 1, comprising a transparent laser marking sheet containing 0.1 to 5 parts by mass of an inhibitor and / or anti-coloring agent and 0.1 to 5 parts by mass of an ultraviolet absorber and / or a light stabilizer. Sheet. The transparent laser marking sheet A has a skin layer and a core layer, and is a transparent laser marking sheet formed by melt extrusion molding,
The skin layer is made of a transparent resin whose main component is polycarbonate resin, and the core layer is 0.0005 to 1 part by mass of a laser light energy absorbing material with respect to 100 parts by mass of the transparent resin whose main component is a polycarbonate resin. Comprising a transparent polycarbonate resin composition containing,
The total thickness of the transparent laser marking sheet A is 50 to 200 μm, and the thickness ratio of the core layer to the total thickness of the transparent laser marking sheet A is 20% or more to less than 90%. The laser marking multilayer sheet according to claim 1, comprising a multilayer sheet.   The skin layer of the transparent laser marking sheet A contains 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 the skin layer of the transparent laser marking sheet A and / Or 0.1 to 5 parts by mass of an antioxidant and / or anti-coloring agent, and an ultraviolet absorber and / or a light stabilizer for 100 parts by mass of a transparent resin whose main component is a polycarbonate resin The laser marking multilayer sheet according to claim 3, comprising a transparent laser marking sheet containing 1 to 5 parts by mass.   The laser light energy absorbing material of the transparent laser marking sheet A contains at least one or two or more of carbon black, titanium black, metal oxide, metal sulfide, and metal nitride. The laser marking multilayer sheet according to any one of the above.   The core layer and / or skin layer of the transparent laser marking sheet A and / or multilayer sheet B is 0.1 to 5 parts by mass of an antioxidant and / or anti-coloring agent and 100% by mass with respect to 100 parts by mass of the thermoplastic resin. The laser marking multilayer sheet according to any one of claims 1 to 5, comprising 0.1 to 5 parts by mass of an absorber and / or a light stabilizer.   The laser marking according to any one of claims 1 to 6, wherein the surface of the transparent laser marking sheet A and / or the multilayer sheet B is matted with an average roughness (Ra) of 0.1 to 5 µm. Multi-layer sheet.   It is an object for electronic passports, The laser marking multilayer sheet of any one of Claims 1-7.   It is an object for plastic cards, The laser marking multilayer sheet of any one of Claims 1-8. A method of laser marking on the laser marking multilayer sheet according to any one of claims 1 to 9,
A laser marking method for printing by irradiating a laser beam from the transparent laser marking sheet A side laminated on the laser marking multilayer sheet.

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