JP7339165B2 - Laminate and adhesive composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to, for example, a laminate for laser marking and an adhesive composition used for the laminate for laser marking.

Laser marking labels are used as nameplates for describing various information or as labels for process control. A laser marking label is a label printed by irradiation with a laser beam. A laser marking label is composed of, for example, a laminate in which two or more layers are laminated on a film. Information such as characters or bar codes is printed by etching the surface layer of the laminate with a laser beam to expose the lower layer. However, when printing with a laser beam, the laser beam penetrates the label and may damage the adherend. Therefore, countermeasures such as thickening the base and providing a shielding layer have been taken.

For example, in Patent Document 1, a white ink layer containing a titanium oxide pigment and a black ink layer containing a carbon pigment are laminated in order on one surface of a transparent substrate, and the other surface of the transparent substrate is made of light-colored ink. Laminates for laser marking are described which are laminated with a shielding layer. Such a laminate for laser marking has a black ink layer on the surface, and when a laser beam is irradiated from the black ink layer side, the black ink layer is scraped off, and the white ink layer or the light color ink layer is exposed, resulting in letters and the like. Display information.

Further, for example, Patent Document 2 describes a laminate for laser marking containing a scale-like filler and a white pigment on the side opposite to the laser-irradiated side of the laser coloring layer in the base film. ing.

Japanese Patent Application Laid-Open No. 2009-119658 (published on June 4, 2009) Japanese Patent No. 6342042 (issued on June 13, 2018)

However, in the laminate for laser marking described in Patent Document 1, when the first layer on the surface is formed with white or light-colored ink, information can be displayed by replacing the white ink layer with a black ink layer. be possible. However, the black ink layer has a high ability to absorb laser light and converts light energy into heat. Therefore, when laser light is applied, a part of the black ink layer may be scraped off to the extent that the surface of the base material layer is exposed. When the black ink layer is scraped off, the color contrast between the laser marking layer and the shielding layer made of light-colored ink is lowered, and there is a problem that the information marked on the laminate cannot be read.

The laminate for laser marking described in Patent Literature 2 has a shielding layer using both a scale-like filler and a white pigment. However, when the content of the scale-like filler is increased, adhesion failure occurs between the shielding layer and the substrate layer, cracks easily occur in the shielding layer itself, and sufficient strength cannot be obtained in the shielding layer. be. Further, when the shielding layer is a pressure-sensitive adhesive layer, a decrease in adhesive strength and a decrease in cohesive strength tend to occur.

Furthermore, a laminate for laser marking, which has a light-colored laser marking layer etched with a laser beam and a dark-colored laser light shielding layer, is in high demand because information can be displayed with dark-colored characters. However, as described above, the dark-colored shielding layer is easily etched together with the laser marking layer by laser light, making it difficult to form a shielding layer with high shielding properties.

In order to solve the above problems, a laminate according to one embodiment of the present invention includes a shielding layer having a shielding property against laser light and a laser marking layer, and the shielding layer comprises a resin component, carbon black, and scaly filler.

Further, a pressure-sensitive adhesive composition according to one embodiment of the present invention is a pressure-sensitive adhesive composition for attaching a laminate for laser marking to an adherend, comprising carbon black, a scale-like filler, and a resin component. contains.

ADVANTAGE OF THE INVENTION According to one Embodiment of this invention, the laminated body for laser marking provided with the shielding layer which has a high shielding property with respect to a laser beam, and its related technology can be provided, although it is a dark color.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure explaining the outline of the laminated body 100 for laser markings which concerns on one Embodiment of this invention. FIG. 2 is a diagram schematically showing a state in which the laminated body 100 shown in FIG. 1 is etched by laser light; BRIEF DESCRIPTION OF THE DRAWINGS It is a figure explaining the outline of the laminated body 101 for laser markings which concerns on one Embodiment of this invention. 4 is a diagram schematically showing a state in which the laminate 101 shown in FIG. 3 is etched by laser light; FIG. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure explaining the outline of the laminated body 102 for laser marking which concerns on one Embodiment of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure explaining the outline of the laminated body 103 for laser markings which concerns on one Embodiment of this invention.

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.

<Laminate 100>
FIG. 1 is a diagram schematically showing an example of the layer structure of a laminate according to one embodiment of the present invention. FIG. 2 is a diagram schematically showing a state in which the laminate shown in FIG. 1 is etched by laser light.

A laminate 100 shown in FIG. 1 is a laminate for laser marking, and is a laminate formed by laminating a shielding layer 1, a substrate layer 2, and a laser marking layer 3 in this order. A film layer including the substrate layer 2 and the laser marking layer (first layer) 3 before the shielding layer 1 is formed is referred to as a laser marking film 10 . The shielding layer 1 of the laminate 100 is a layer that has both properties of shielding against laser light and adhesiveness to adherends. The shielding layer 1 is formed on the back side of the surface of the substrate layer 2 on which the laser marking layer 3 is provided. The laminate 100 is attached to an adherend (not shown) by the adhesive surface 1a of the shielding layer 1 (FIG. 2). As shown in FIGS. 1 and 2, the adhesive surface 1a of the shielding layer 1 of the laminate 100 is protected by a release film F until the laminate 100 is attached to the adherend. is preferred.

In the laminated body 100 shown in FIG. 1, the hue of the shielding layer 1 and the hue of the laser marking layer 3, which face each other with the substrate layer 2 interposed therebetween, are different from each other. The layered body 100 displays information on the surface 3 a of the layered body 100 by means of the color contrast between the shielding layer 1 and the laser marking layer 3 . In the laminate 100 , the shielding layer 1 is darker than the laser marking layer 3 and is toned to a darker hue, and the laser marking layer 3 is brighter than the shielding layer 1 and toned to a lighter hue. In this specification, the surface of the laser marking layer means the surface irradiated with laser light.

As shown in FIG. 2, in the laminate 100, when the surface 3a of the laser marking layer 3 is irradiated with the laser beam B, the pigment and resin contained in the laser marking layer 3 absorb the laser beam B and generate heat. This heat thermally decomposes the resin contained in the laser marking layer 3 and blows off the thermally decomposed resin and pigment. As a result, the laser marking layer 3 is scraped from the surface 3a until the surface of the substrate layer 2 is exposed, thereby forming a printed portion 10a on the laser marking layer 3. As shown in FIG. Cutting out the laser marking layer 3 with the laser beam B in this way is called etching.

The laser for etching the laser marking layer (first layer) 3 can be appropriately selected within a range in which the laser that reaches from the laser marking layer 3 to the substrate layer 2 can be irradiated. Examples of lasers that can be irradiated with the laser light include _CO2 lasers, Yb lasers, _YVO4 lasers, Nd:YAG lasers, excimer lasers, semiconductor lasers, semiconductor pumped solid-state lasers, Ar lasers, _N2 /Dye lasers and HeCd lasers. Includes a laser. Among them, Yb laser, _YVO4 laser and Nd:YAG laser are called short wavelength lasers. CO ₂ laser, Yb laser, YVO ₄ laser, and Nd:YAG laser are generally preferred from the viewpoint of inexpensive equipment and relatively easy handling.

Irradiation with laser light can be performed as appropriate according to the laser wavelength, laser output, pulse period, and spot diameter. For example, if the Yb laser has an output of 13 W, a pulse period of 50 Hz, and a spot diameter (line width of 70 μm), the scanning speed of the laser light may be 100 to 3000 mm/sec.

In the laminated body 100, when the substrate layer 2 is exposed by etching with a laser beam, the shade of the shielding layer 1 can be seen through the substrate layer 2 from the printed portion 10a formed by scraping the laser marking layer 3 from the surface 3a. is confirmed. More specifically, when the laminate 100 is viewed from the surface 3a side, the dark and deep hue of the shielding layer 1 is displayed inside the printed portion 10a formed by scanning the laser beam B, and the printed portion 10a is displayed. A brighter and paler hue is displayed by the laser marking layer 3 on the outer surface 3a than the inner side. Information is displayed on the surface 3a by contrast due to the different hues of the shielding layer 1 and the laser marking layer 3 and the shape of the printed portion 10a formed by etching when viewed from above. Here, the information may be information formed by etching the laser marking layer 3 with the laser beam B, for example, characters such as hiragana, kanji, alphanumeric characters, barcodes, two-dimensional It may be information such as a code. By peeling off the release film F from the laminate 100 , the laminate 100 (label) having a print can be attached to a desired adherend via the shielding layer 1 .

In this specification, the same hue refers to a color difference that is difficult to visually distinguish. The difference in L values measured by the SCE) method is less than 7, preferably less than 5. In this specification, different hues refer to visible color differences. 7 or more, preferably 10 or more. Among them, hues with lower L values are darker and darker hues, and hues with higher L values are lighter and lighter hues.

The structure of each layer included in the laminate 100 will be described in more detail below.

[Shielding layer 1]
The shielding layer 1 contains scale-like fillers and carbon black as pigments, and contains a resin component. The scale-like filler and carbon black dispersed in the resin component give the shielding layer 1 a deep black hue that is darker than the hue of the laser marking layer 3 . In addition, since the scale-like filler and carbon black are contained, the shielding layer 1 has a deep black hue and has extremely high laser light shielding properties.

The film thickness of the shielding layer 1 is in the range of 1 μm or more and 200 μm or less, and more preferably in the range of 5 μm or more and 100 μm or less. When the film thickness of the shielding layer 1 is 5 μm or more, a shielding layer having high shielding properties can be formed. It can be adhered by suitably conforming to irregularities. Further, by setting the film thickness of the shielding layer 1 to 100 μm or less, the step from the surface of the adherend to the surface 3a of the laminate 100 can be reduced when the laminate 100 is attached.

[1] Pigment The shielding layer 1 contains scale-like filler and carbon black as pigments. The carbon black dispersed in the resin component of the shielding layer 1 gives the shielding layer 1 a deep black hue that is darker than the hue of the laser marking layer 3. Increase shielding.

[1-1] Scaly filler and carbon black The content of the scaly filler is in the range of 4.5 parts by mass or more and 30 parts by mass or less when the amount of the resin component contained in the shielding layer 1 is 100 parts by mass. preferably included. When the content of the scale-like filler is 30 parts by mass or less, it is possible to prevent cohesive failure of the shielding layer 1 and the occurrence of adhesive residue when the laminate is peeled off from the adherend. Therefore, the laminated body can be preferably reattached. In addition, by including 4.5 parts by mass or more of the scale-like filler with respect to 100 parts by mass of the resin component, it is possible to obtain the shielding layer 1 that can suitably shield light from laser irradiation.

The scale-like filler is preferably, for example, a metal oxide-coated filler obtained by coating a scale-like filler such as mica with a metal oxide. , zinc oxide, zirconium oxide, iron oxide, chromium oxide, tin oxide and talc. In addition, scale-like metal fillers such as aluminum paste can be used. Other scaly fillers include scaly silica, alumina, glass flakes, and bismuth oxychloride.

The scale-like filler is more preferably titanium oxide-coated mica because it can reflect long-wavelength light such as red light to the shielding layer 1 . By including the titanium oxide-coated mica in the shielding layer 1, the reflectance of red light can be lowered, and reading errors can be made less likely to occur when reading a one-dimensional code or a two-dimensional code. In addition, the scale-like filler may be, for example, mica that is not coated with a metal oxide, and the mica may be natural mica or synthetic mica. Natural mica includes muscovite, phlogopite, and the like, and synthetic mica includes fluorine phlogopite, potassium tetrasilisic mica, sodium tetrasilisic mica, and the like.

In addition, the shielding layer 1 can form a black layer with high shielding properties by containing the scale-like filler and carbon black. More specifically, carbon black has the property of absorbing laser light and generating heat. Due to this property, the shielding layer containing carbon black accelerates the combustion and decomposition of the resin, making it easier for laser light to penetrate the shielding layer. However, by adding, for example, titanium oxide-coated mica as a scale-like filler to the shielding layer containing carbon black, the laser beam is reflected by the scale-like filler. In addition, the shielding layer 1 contains scale-like fillers as incombustibles, which reduces combustibility. As a result, it is presumed that heat generation due to absorption of laser light by the shielding layer can be suppressed, and penetration due to burning or decomposition of the resin can be suppressed. Further, for example, the reflectance of titanium oxide-coated mica to laser light with a wavelength of 1000 to 1100 nm, which is the wavelength of a short-wave laser, or 10,000 nm to 11,000 nm, which is the wavelength of a CO ₂ laser light, is 100 in the amount that can be added to the resin component. expected to be less than 10%. However, the inventors of the present application have found a tendency to favorably suppress the transmission of laser light by allowing carbon black to absorb the laser light, and completed the present invention.

As described above, carbon black can suitably block light with wavelengths in the vicinity of 1000 nm to 1100 nm and 10000 nm to 11000 nm, but it also has an excellent ability to convert absorbed light energy into heat. Therefore, if it is blended in a large amount, it will generate heat to accelerate the combustion and decomposition of the resin. Therefore, the content of carbon black contained in the shielding layer 1 is preferably 0.5 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the resin component.

[1-2] Other Coloring Pigments The shielding layer 1 contains other coloring pigments within a range that does not impair the effect of the present invention and does not impair the hue contrast with the laser marking layer (first layer) 3 described later. may contain.

[2] Resin Component Contained in Shielding Layer 1 The shielding layer 1 contains an acrylic copolymer and a cross-linking agent as resin components, and may further contain a tackifying resin as a resin component.

The shielding layer 1 may further contain components other than the resin component within the range where the effect of the present embodiment is exhibited. For example, the shielding layer 1 may contain one or more resins other than pigments, examples of which include polyols, urethane resins, and cellulose resins.

[2-1] Acrylic Copolymer Contained in Shielding Layer 1 In the present specification, the “acrylic copolymer” is a polymer or copolymer containing (meth)acrylic acid and its derivatives as monomers. "(Meth)acrylic" means one or both of acrylic and methacrylic. Moreover, "(meth)acrylate" means one or both of acrylate and methacrylate. Furthermore, "(meth)acrylic monomer" means at least one of acrylic acid, derivatives thereof, methacrylic acid and derivatives thereof. The acrylic copolymer described below reacts with the cross-linking agent and is contained in the shielding layer 1 as a product.

The acrylic copolymer contained in the shielding layer 1 includes a (meth)acrylic monomer which is the main monomer component of the acrylic copolymer and a (meth)acrylic monomer having a carboxyl group, or a (meth)acrylic monomer having a hydroxyl group. ) acrylic monomers, or both.

Examples of (meth)acrylic monomers, which are the main monomer components of acrylic copolymers, include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth) Acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, t-butyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, cyclohexyl ( meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, isobornyl (meth)acrylate, 2-methoxy (meth)acrylate, 2-ethoxy (meth)acrylate, glycidyl (meth)acrylate and tetrahydrofurfuryl (meth)acrylate. One or more of these acrylic monomer components may be used.

Among them, the (meth)acrylic monomer, which is the main monomer component of the acrylic copolymer contained in the shielding layer 1, is methyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate. , t-butyl (meth)acrylate and the like. When used as an adhesive composition, n-butyl acrylate is most preferred.

The ratio of the (meth)acrylic monomer, which is the main monomer component of the acrylic copolymer contained in the shielding layer 1, is 80% by mass or more, more preferably 90% by mass or more. In addition, since the ratio of the (meth)acrylic monomer, which is the main monomer component of the acrylic copolymer contained in the shielding layer 1, is 80% by mass or more, it is suitable for attaching to the adherend. A shielding layer 1 having adhesive properties can be formed. Moreover, even if the resin component containing the scale-like filler and carbon black is irradiated with the laser beam B, the shielding layer 1 having adhesiveness can be formed while preventing decomposition due to heat generation. That is, a function as an adhesive layer can be imparted to the shielding layer 1 .

Examples of (meth)acrylic monomers having a carboxyl group include (meth)acrylic acid, crotonic acid, maleic anhydride, fumaric acid, itaconic acid, glutaconic acid and citraconic acid. One or more of these monomers may be used. The ratio of the acrylic monomer having a carboxyl group in the acrylic copolymer is preferably 10% by mass or less.

The acrylic copolymer contained in the shielding layer 1 may contain a (meth)acrylic monomer having a hydroxyl group. Containing a (meth)acrylic monomer having a hydroxyl group causes a cross-linking reaction with a cross-linking agent in the same manner as containing a (meth)acrylic monomer having a carboxyl group.

Examples of (meth)acrylic monomers having a hydroxyl group include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate , 3-methyl-3-hydroxybutyl (meth)acrylate, 1,3-dimethyl-3-hydroxybutyl (meth)acrylate, 2,2,4-trimethyl-3-hydroxypentyl (meth)acrylate, 2-ethyl- 3-hydroxyhexyl (meth)acrylate, polypropylene glycol mono(meth)acrylate, polyethylene glycol mono(meth)acrylate, poly(ethylene glycol-propylene glycol) mono(meth)acrylate and pentaerythritol tri(meth)acrylate. One or more hydroxyl group-containing (meth)acrylic monomers may be used.

In addition, the acrylic copolymer may contain a monomer copolymerizable with the (meth)acrylic monomer as long as the effects of the present invention are not impaired. Such copolymerizable monomers include, for example, vinyl esters such as vinyl acetate, vinyl ethers, acrylonitrile, and styrene.

Although the weight average molecular weight (Mw) of the acrylic copolymer contained in the shielding layer 1 is not limited, it is preferably 5,000 or more and 1,000,000 or less. It is preferable that the weight average molecular weight of the acrylic copolymer is 5000 or more from the viewpoint of enhancing the drying properties of the coating liquid composition for forming the shielding layer 1 . It is preferable that the mass average molecular weight of the acrylic copolymer is 400,000 or more from the viewpoint of imparting cohesion to the shielding layer 1 as an adhesive layer. It is preferable that the weight average molecular weight of the acrylic copolymer is 1,000,000 or less from the viewpoint of obtaining a coating liquid composition having good workability during coating. Further, it is preferable that the acrylic copolymer has a mass average molecular weight of 800,000 or less from the viewpoint of obtaining a coating liquid composition having good workability during coating. The shielding layer 1 having adhesiveness is preferable from the viewpoint that it easily conforms to the unevenness of the adherend.

The mass average molecular weight of the acrylic copolymer can be determined by a standard polystyrene conversion method using gel permeation chromatography (GPC).

Further, the glass transition temperature of the acrylic copolymer is preferably 40° C. or higher, and preferably 60° C. or higher, from the viewpoint of exhibiting good drying properties when the shielding layer is formed by applying the coating liquid composition. It is more preferable to have Further, the glass transition temperature of the acrylic copolymer is preferably 100° C. or less from the viewpoint of obtaining a coating liquid that is easy to handle when formed by applying the coating liquid composition. From another point of view, the glass transition temperature of the acrylic copolymer contained in the shielding layer 1 is preferably −60° C. or higher from the viewpoint of cohesion. In addition, from the viewpoint of suitably developing surface tack on the adhesive surface 1a, the temperature is preferably −20° C. or lower. Thereby, the shielding layer 1 can be provided with a function (that is, adhesiveness) as an adhesive layer.

The glass transition temperature of the acrylic copolymer can be roughly estimated as the sum of the glass transition temperatures according to the mass ratio of the (meth)acrylic monomers that are the monomers of the acrylic copolymer. A rough estimate of the glass transition temperature Tg of acrylic acid is determined by the following formula. In the formula below, Tg ₁ to Tg _n represent the glass transition temperatures (K) of the (meth)acrylic monomers 1 to n constituting the (meth)acrylic copolymer. In the formula below, w ₁ to w _n represent the ratio of the mass of each monomer to the total mass of the (meth)acrylic monomers 1 to n. n represents the type of (meth)acrylic monomer and is an integer of 2 or more.

Although the glass transition temperature Tg of acrylic acid is obtained using absolute temperature (K), it is expressed in degrees Celsius (° C.) in this specification.

The glass transition temperature _Tgn of the (meth)acrylic monomer is obtained as the temperature at the inflection point of the DSC curve obtained by measuring under the following conditions using a differential scanning calorimeter (DSC).
Differential scanning calorimetry (DSC) measuring device “EXSTAR6000” (manufactured by Seiko Instruments Inc.)
Atmosphere Nitrogen stream Amount of measurement sample 10 mg
Heating rate 10°C/min

Typical glass transition temperatures of (meth) acrylic monomers are methyl methacrylate: 103° C., n-butyl methacrylate: 21° C., butyl acrylate: −57° C., 2-hydroxyethyl methacrylate: 55° C., 2-hydroxy Ethyl acrylate: -15°C, acrylic acid: 166°C, methacrylic acid: 185°C, etc.

The resin component contained in the light shielding layer may contain one, two or more acrylic copolymers.

[2-2] Cross-linking agent The cross-linking agent is a cross-linking agent that cross-links the acrylic copolymer. The shielding layer 1 produces a crosslinked product of the acrylic copolymer by reacting with the carboxyl groups and hydroxyl groups that the acrylic copolymer has in the main chain skeleton.

[2-2-1] Polyisocyanate The cross-linking agent for the acrylic copolymer is typically polyisocyanate. Polyisocyanate reacts with carboxyl groups and/or hydroxyl groups possessed by acrylic copolymers.

The content of polyisocyanate in the resin component contained in the shielding layer 1 is preferably determined based on the content of isocyanate groups possessed by the polyisocyanate. The isocyanate group equivalent to the total amount of carboxyl groups and hydroxyl groups of the acrylic copolymer in the resin component of the shielding layer 1 is preferably 0.1 equivalent or more and 2.0 equivalent or less.

Examples of polyisocyanates include polymeric MDIs such as xylylene diisocyanate (XDI), diphenylmethane diisocyanate (MDI), triphenylmethane triisocyanate, and aromatic polyisocyanate compounds such as tolylene diisocyanate (TDI).

Examples of aliphatic or cycloaliphatic isocyanates include hexamethylene diisocyanate (HDI), heptamethylene diisocyanate, isophorone diisocyanate (IPDI), hydrogenated xylylene diisocyanates (hydrogenated XDI) such as 1,4-cyclohexanebismethyl isocyanate. , and hydrogenated diphenylmethane diisocyanates (hydrogenated MDI) such as 4,4-methylenebiscyclohexyl isocyanate. From the viewpoint of suppressing discoloration of the shielding layer 1, the polyisocyanate is preferably an aliphatic or alicyclic polyisocyanate.

Examples of polyisocyanates include dimers or trimers of isocyanate compounds. Examples of such polyisocyanates include uretdiones or isocyanurates, prepolymers of isocyanate compounds and polyol resins.

Examples of such polyisocyanates include adducts of isocyanates and polyhydric alcohols or urea compounds. Examples of such polyhydric alcohols include propylene glycol (difunctional alcohol), butylene glycol (difunctional alcohol), trimethylolpropane (TMP, trifunctional alcohol), glycerin (trifunctional alcohol) and pentaerythritol (tetrafunctional alcohol). is included.

Examples of the above adducts include adducts of tolylene diisocyanate and trifunctional alcohol, adducts of isophorone diisocyanate and difunctional alcohol, and adducts of isophorone diisocyanate and trifunctional alcohol.

Polyisocyanates may be commercially available.

[2-2-2] Other cross-linking agents Examples of cross-linking agents other than polyisocyanate include melamine-based cross-linking agents, benzoguanamine-based cross-linking agents, urea-based cross-linking agents, metal chelate-based cross-linking agents, organosilane-based cross-linking agents, epoxy cross-linking agents and anhydride-based cross-linking agents. Examples of melamine-based cross-linking agents include Nikalac (registered trademark) MS-11 and MS-001 (both manufactured by Nippon Carbide Industry Co., Ltd.), and Mycoat 715 (manufactured by Nippon Cytec Industries Co., Ltd., "Mycoat" is Orne). (registered trademark of Kusu Japan Co., Ltd.).

[2-3] Tackifier resin The shielding layer 1 preferably contains a tackifier resin as a resin component. Tackifier resins are also referred to as tackifier resins. The inclusion of the tackifying resin in the shielding layer 1 enhances the tackiness of the shielding layer. Tackifying resins include, for example, terpene-based resins, rosin-based resins, and petroleum-based resins. Further, the tackifying resin is preferably a rosin ester because it bleeds less onto the adhesive surface 1a and has high durability against solvents.

[2-4] Other Components In addition, the shielding layer 1 may contain stabilizers such as antioxidants and UV absorbers, leveling agents, anti-settling agents, and antifoaming agents, as long as the effects of the present invention are not impaired. and additives such as surfactants such as wetting and dispersing agents, and plasticizers as other components.

[Base material layer 2]
The substrate layer 2 may be optically transparent. “Optically transparent” means, for example, that the visible light transmittance is 80% or more and the laser light transmittance is 50% or more. When the transmittance of visible light in the substrate layer is sufficiently high, when the layered product (label) after etching is viewed from the side of the laser marking layer 3, the hue of the shielding layer 1 can be sufficiently seen through the substrate layer 2. Visual recognition becomes possible.

In addition, the absorptance of the laser beam in the substrate layer 2 is affected by the shielding layer 1 arranged on the opposite side of the laser marking layer 3 than the substrate layer 2 in etching, and through holes are formed in the substrate layer 2. From the viewpoint of suppressing this, the lower the value, the better. On the other hand, the higher the transmittance of the laser beam in the substrate layer 2 is, the better. By increasing the transmittance, the reflection and scattering of the laser light toward the laser marking layer 3 in the substrate layer 2 can be suppressed, so that finer etching can be realized. From this point of view, the laser light transmittance of the substrate layer 2 may be 50% or more. The light transmittance of the substrate layer may be uniform in one laminate, or may vary depending on the portion to be etched.

The shape of the base material layer 2 is not limited. The thickness of the base material layer 2 may be constant, or may have different thicknesses in one laminate. The substrate layer 2 is preferably a resin substrate film because it is generally preferable for the laminate (or the label after etching) to have flexibility from the viewpoint of increasing the versatility of the label. The thickness of the film is not limited, and can be appropriately determined, for example, from the viewpoint of the range in which the above-described through-holes are not formed during etching and from the viewpoint of handleability. From this point of view, the thickness of the film may be, for example, 25-300 μm.

For the resin component contained in the base material layer 2, for example, a material generally having high transparency can be used. Examples of such materials include glass and thermoplastic resins (thermoplastics) such as ester resins, polycarbonate resins, acrylic resins, and thermoplastic urethane resins. A thermoplastic resin is preferred. Among them, it is preferable that the base material layer is composed of a thermoplastic resin such as an ester-based resin, from the viewpoint of enhancing the versatility of the laminate and from the viewpoint of realizing fine laser marking.

From the viewpoint of suppressing deformation due to heat during laser marking, the ester-based resin is preferably an aromatic ester-based resin. The aromatic ester-based resin is more preferably a transparent resin from the viewpoint of suppressing deformation due to heat during laser light irradiation.

Examples of aromatic ester resins include polyethylene terephthalate, polybutylene terephthalate, polycyclohexylene dimethylene terephthalate and polyethylene naphthalate. Among them, it is preferable that the aromatic ester-based resin is polyethylene terephthalate from the above-mentioned viewpoint.

The base material layer 2 may be subjected to a treatment for enhancing adhesion with adjacent layers such as the shielding layer 1 and the laser marking layer 3 . For example, in the case of the base layer 2 made of an aromatic ester resin, the base layer 2 has a laser marking layer 3 and a shielding layer on the surface of the base layer 2 in order to increase the adhesion to the laser marking layer 3. A portion that is in contact with another layer such as layer 1 may be subjected to a treatment for enhancing adhesion, such as corona treatment or formation of an easy-adhesion coat.

[Laser marking layer 3]
The laser marking layer 3 is a layer that is etched with a laser beam and has a hue different from that of the shielding layer 1 . A laser marking layer included in the laminate may be referred to as a first layer. As a material for the laser marking layer 3, a known material having absorptivity to laser light can be used. Therefore, in the laser marking layer 3, the continuous phase (for example, the resin component) in the portion irradiated with the laser beam when viewed from above is decomposed by light and heat. In addition, the laser marking layer 3 may contain various coloring pigments including a white pigment at least within a range that does not impair the hue contrast with the shielding layer 1 .

The thickness of the laser marking layer 3 is preferably 20 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less. By setting the film thickness of the laser marking layer 3 to 20 μm or less, it is possible to sufficiently etch the laser marking layer 3 by irradiating it with a laser beam, thereby preventing defective printing. In addition, it is possible to avoid excessively increasing the intensity of the laser beam for penetrating the laser marking layer 3, thereby preventing adverse effects on the underlying layers. From the viewpoint of sufficiently etching the laser marking layer 3 by laser light irradiation, the thickness of the laser marking layer 3 is preferably 20 μm or less, more preferably 15 μm or less, and 10 μm or less. is more preferred.

The thickness of the laser marking layer 3 is preferably 2 μm or more, and preferably 6 μm or more, in order to sufficiently conceal the colors of the laser absorption layer 4, the base layer 2, and the shielding layer 1, which will be described later. It is more preferable that the thickness is 10 μm or more.

[1] Color Pigment Color pigments contained in the laser marking layer 3 include, for example, white pigments and organic pigments.

[1-1] White Pigment White pigments include, for example, titanium oxide, zinc oxide (zinc oxide), basic lead sulfate, zinc sulfide, and antimony oxide. White pigments may also include barium sulfate, barium carbonate, precipitated calcium carbonate, diatomaceous earth, talc, clay, basic magnesium carbonate, and alumina white. These white pigments can be contained in the laser marking layer 3 in an amount that does not excessively impair the absorption of laser light with respect to the resin component constituting the continuous phase in the laser marking layer 3 .

The content of the white pigment in the laser marking layer 3 is preferably 50 parts by mass or more and 300 parts by mass or less based on 100 parts by mass of the resin component contained in the laser marking layer 3 . When the content of the white pigment contained in the laser marking layer 3 is 50 parts by mass or more, it is possible to prevent the hue of the shielding layer 1 from being seen through the laser marking layer 3 . Further, when the resin component contained in the laser marking layer 3 is 100 parts by mass, the resin component of the laser marking layer 3 is thermally decomposed by irradiating the laser marking layer 3 with a laser beam of an appropriate output so that the amount is 300 parts by mass or less. The printing portion 10a can be preferably formed.

The volume median diameter of the white pigment is preferably 0.1 to 1 μm from the viewpoint of increasing light reflectance. The volume median diameter of the white pigment is a particle diameter (D50) corresponding to cumulative 50% in a volume-based particle size distribution determined by a laser diffraction/scattering method.

[1-2] Organic Pigment In addition, the laser marking layer 3 may contain an organic pigment within a range that does not impair the hue contrast with respect to the shielding layer 1 . Examples of organic pigments include cyanine pigments having an extended polymethine skeleton, nickel dithiolene pigments having a four-planar coordination structure, squalium pigments, naphthoquinone pigments, diimmonium pigments, azo organic pigments, and phthalocyanines. and condensed polycyclic organic pigments such as polycyclic pigments, naphthalocyanine pigments, and azulenocyanine pigments. Examples of azulenocyanine-based pigments include (10, 12, 22, 24, 34, 36, 46, 48-octooctyl) 2,3-azulenocyanine zinc. Furthermore, the organic pigment may be a commercially available product, examples of which include near-infrared absorbing dye "FDN-010" manufactured by Yamada Chemical Industry Co., Ltd., and near-infrared absorbing dye manufactured by Yamamoto Kasei Co., Ltd. The dye "YKR-2200" is included. In addition, the laser marking layer 3 may contain carbon black as an organic pigment in an amount that does not impair the hue contrast with the shielding layer 1 on the surface 3a of the laminate 100 .

That is, the color exhibited by the material of the laser marking layer 3 may be appropriately determined according to the color exhibited by the shielding layer 1 within the range in which the printed characters are sufficiently clearly displayed.

The content of the organic pigment other than the white pigment contained in the laser marking layer 3 is not limited as long as the difference in L value with respect to the hue of the shielding layer 1 is 7 or more, preferably 10 or more, and the laser marking layer 3' described later. It can be used as the content of the organic pigment contained in.

[2] Resin Component Contained in Laser Marking Layer 3 The laser marking layer 3 contains an acrylic copolymer as a resin component.

The laser marking layer 3 may further contain materials other than the resin component and the pigment as long as the effects of the present embodiment are exhibited. For example, one or more resins other than pigments may be used in the laser marking layer 3, and examples thereof include polyols, urethane resins, cellulose resins, and cross-linking agents such as polyisocyanate.

<Laminate 101 according to another embodiment>
A laminate according to an embodiment of the present invention is not limited to the laminate 100 according to the above embodiment. For example, as shown in FIG. 3, the laminate 101 according to one embodiment of the present invention includes, from the surface 3a side, a laser marking layer (first layer) 3, a laser marking layer (first layer) 3', It is a laminate in which a laser absorption layer (second layer) 4, a substrate layer 2, and a shielding layer 1 are laminated in this order. That is, a laser marking layer 3 ′ and a laser absorbing layer 4 are laminated between the laser marking layer 3 and the substrate layer 2 . In the laminate 101 , the film layer including the base layer 2 , the laser marking layers 3 and 3 ′, and the laser absorbing layer 4 before the shielding layer 1 is formed is referred to as a laser marking film 11 .

As shown in FIG. 4, the laminated body 101 is irradiated with a laser beam from the surface 3a side toward the laminated body 101, so that the laser marking layers 3 and 3' and the laser absorption layer 4 are etched together, and the surface A printing portion 11a is formed on the 3a side. In the laminate 101, members having the same functions as the members of the laminate 100 are denoted by the same reference numerals as in the laminate 100, and descriptions thereof are omitted.

[Laser marking layer 3']
The laser marking layer 3 ′ is a layer serving as a base for the laser marking layer 3 in the laminate 101 viewed from the surface 3 a side, and is a layer provided between the laser marking layer 3 and the laser absorption layer 4 . The laser marking layer 3' contains both organic pigments such as carbon black and white pigments. The laser marking layer 3' has an intermediate hue between the light and bright laser marking layer 3 and the deep and dark laser absorbing layer 4. As shown in FIG. This prevents the color of the laser marking layer 3 from changing due to the color of the laser absorbing layer 4 and the shielding layer 1 being seen through the surface 3 a of the laminate 101 .

The laser marking layer 3 ′ is one aspect of the laser marking layer 3 , and the content of the color pigment contained in the resin component conforms to the content of these pigments in the laser marking layer 3 . Further, since the laser marking layer 3' contains the same resin component as that of the laser marking layer 3, the description of the resin component is omitted.

The laser marking layer 3 ′ is one aspect of the laser marking layer 3 , and the total thickness of the laser marking layer 3 and the thickness of the laser marking layer 3 is preferably 1 μm or more and 20 μm or less.

[Laser absorption layer 4]
Like the laser marking layer 3 , the laser absorption layer 4 is a layer that absorbs laser light, but may have the same hue as the shielding layer 1 . This point differs from the laser marking layer 3 . Moreover, the laser absorption layer 4 differs from the shielding layer 1 in that it does not substantially contain scale-like fillers. “Substantially free of scale-like filler” means that the laser absorbing layer 4 does not substantially contain the filler to the extent that it does not function as the shielding layer 1 . These differences distinguish the laser absorbing layer 4 from the laser marking layer 3 and the shielding layer 1 . The laser absorption layer 4 that absorbs laser light is sometimes called a second layer to distinguish it from the laser marking layer (first layer).

The laser absorbing layer 4 contains an organic pigment as the main pigment, preferably carbon black as the organic pigment. Since the laser absorption layer 4 contains an organic pigment, it has a dark and dark hue, and substantially does not contain a scale-like filler, so that the laser light shielding property is low. In other words, the laser absorption layer does not easily reflect the laser beam, so the organic pigment contained in the laser absorption layer absorbs the laser beam and easily generates heat. For this reason, the laser absorption layer 4 is easily thermally decomposed and easily generates gas that may be generated by the decomposition of the resin component. Therefore, when the laser absorbing layer 4 absorbs the laser light and decomposes, both the laser marking layers 3 and 3′ located on the laser absorbing layer 4 are etched, and as a result, the surface 3a of the laminate 101 is etched. Fine printing can be performed. Moreover, in the laminate 101 according to one embodiment of the present invention, for example, as shown in FIG. laser light can be shielded at In addition, the shielding layer 1 can shield long wavelength laser light while having a black hue. Therefore, the adherend attached to the adhesive surface 1a of the laminate 101 can be prevented from being damaged by the laser beam, and the hue of the shielding layer 1 can maintain a high hue contrast with the laser marking layer 3. Therefore, information such as a bar code or a two-dimensional code printed on the laminate 101 for laser marking can be preferably read by a code reader for reading the information.

The thickness of the laser absorption layer 4 is preferably 0.5 μm or more, more preferably 1 μm or more, and more preferably 2 μm or more from the viewpoint of stably and easily producing the laser absorption layer 4 . More preferred.

The organic pigment contained in the laser absorption layer 4 is an organic pigment that can be contained in the laser marking layer 3 described above, more preferably carbon black.

<Laminate 102 according to yet another embodiment>
A laminate according to an embodiment of the present invention is not limited to the laminate 100 and the laminate 101 described above. For example, as shown in FIG. 5, a laminate 102 according to yet another embodiment of the present invention includes a shielding layer 1′ and an adhesive layer on the surface of the substrate layer 2 facing the surface 3a of the film 11 for laser marking. Agent layers 5 are laminated in this order. In the laminate 102, the adhesive layer 5 is attached to the adherend via the adhesive surface 5a. Even with this configuration, even if the laser beam irradiated from the surface 3a side passes through the base material layer 2 and is irradiated onto the shielding layer 1′, the laser beam can be suitably shielded by the shielding layer 1′.

[Shielding layer 1']
The shielding layer 1 ′ contains scale-like filler and carbon black, and may contain the same resin component as the resin component of the laser marking layer 3 as a resin component. The shielding layer 1' contains scale-like fillers and carbon black, so that it can shield the laser light like the shielding layer 1, but does not necessarily have to function as an adhesive layer.

Since the contents of the scale-like filler and carbon black contained in the shielding layer 1' are the same as those of the shielding layer 1, the description thereof is omitted.

[Adhesive layer 5]
The pressure-sensitive adhesive layer 5 only needs to have adhesiveness enough to attach the laminate 102 to an adherend (not shown), and does not substantially contain carbon black and scale-like fillers.

In this specification, the composition for forming the pressure-sensitive adhesive layer that does not substantially contain carbon black and scale-like filler is simply referred to as "adhesive", whereby the shielding layer It is distinguished from the "adhesive composition" which is one embodiment of the "coating composition" for forming 1 and 1'.

The pressure-sensitive adhesive layer 5 may be formed from a known pressure-sensitive adhesive such as an acrylic pressure-sensitive adhesive, a silicone rubber-based pressure-sensitive adhesive, or a synthetic rubber-based pressure-sensitive adhesive. More preferably, the composition for forming the agent layer 5 is an acrylic adhesive.

The film thickness of the pressure-sensitive adhesive layer 5 is in the range of 1 μm to 200 μm, more preferably in the range of 5 μm to 100 μm. When the film thickness of the shielding layer 1 is 5 μm or more, the adhesive layer 5 having the next preferable adhesiveness can be formed. It can be adhered by suitably following the curved surface and irregularities of the adherend.

<Laminate 103 according to yet another embodiment>
The laminate according to one embodiment of the present invention is not limited to the laminate 100, the laminate 101, and the laminate 102 described above. For example, as shown in FIG. 6, a laminate 103 according to still another embodiment of the present invention is formed by laminating a shielding layer 1″, a laser marking layer 3, and an adhesive layer 5 in this order. Laminate 103 The film 13 for laser marking comprises a shielding layer 1 ″ and a laser marking layer 3 . In the laminate 103, the adhesive layer 5 is formed on the shielding layer 1'' side of the film 13 for laser marking.

[Shielding layer 1″]
The contents of the flake-like filler and carbon black contained in the shielding layer 1″ are the same as those of the shielding layer 1, so the description thereof is omitted.

<Other laminates>
The laminate according to the present invention is not limited to the laminates 100, 101, and 102 described above. For example, a laminate according to yet another embodiment is formed by laminating a shielding layer and a laser marking layer in this order, the laser marking layer having the same configuration as the laser marking layer 3 described above, and the shielding layer described above. It has the same structure as the shielding layer 1 or shielding layer 1' of . As a result, it is possible to obtain a laminate for laser marking having a shielding layer having a high shielding property against laser light.

<Method for manufacturing laminate>
A method for manufacturing a laminate according to an embodiment of the present invention can be manufactured using a known method for manufacturing a laminate for laser marking. For example, a laminate according to one embodiment includes the steps of providing a shielding layer and forming a laser marking layer (first layer).

Moreover, the method for manufacturing a laminate according to one embodiment may include a step of forming a laser absorption layer (second layer), and may include a step of forming an adhesive layer.

The step of applying the coating liquid composition or ink may be a step of applying the coating liquid composition or ink onto the substrate layer (substrate film). is a known coating method. Examples of such coating methods include screen printing, gravure printing, bar coating, knife coating, roll coating, comma coating, blade coating, die coating, spray coating, electrostatic coating and dip coating. included.

The step of drying the coating liquid composition or ink to form a coating layer or ink layer can be, for example, a step of drying the coating liquid composition or ink by heating with a known heating device. The heating device includes, for example, an infrared heater, a hot air heater, or a heating device such as an oven or a hot plate. In the step of forming the coating layer, the evaporation of the diluent contained in the coating liquid composition or ink and the crosslinking reaction of the resin component contained in the coating liquid composition or ink are accelerated to form the coating layer or An ink layer is formed.

In the step of curing the coating layer or ink layer and forming the shielding layer, the laser marking layer or the laser absorbing layer, the coating layer, the laser marking layer or the laser absorbing layer is heated by the above-described known heating device. The cross-linking reaction of the resin component contained in the coating layer or ink layer is preferably completed to the extent that the function as a shielding layer, laser marking layer, or laser absorbing layer can be exhibited.

In addition, in the step of preparing the shielding layer, a thermoplastic resin for film molding is used as a resin component, a scale-like filler and carbon black are melt-kneaded into the resin component, and then, for example, extrusion molding, stretching molding, pressing It may be a step of forming into a film by a known forming method such as forming, blow forming, and inflation forming. Moreover, the preparation method for the step of preparing the shielding layer is not limited as long as the substrate film containing the scale-like filler and carbon black can be obtained.

A method for producing a laminate comprises forming a plurality of ink layers on a substrate layer and providing a plurality of laser marking layers (first layers) having different hues within the range in which the effects of the present invention can be obtained. may be formed. Moreover, this may form a laminate in which the substrate layer, the laser absorption layer (second layer) and the laser marking layer (first layer) are laminated in this order.

〔summary〕
A laminate according to one embodiment of the present invention is a laminate for laser marking and includes a shielding layer having a shielding property against laser light and a laser marking layer, the shielding layer comprising a resin component, carbon black , and scaly fillers. As a result, the layered body can be printed clearly on the surface of the layered body by using the shielding layer having a dark color and high shielding properties.

More preferably, in the laminate according to one embodiment of the present invention, the scale-like filler is titanium oxide-coated mica. As a result, the laminate can have a low reflectance for red light, and reading errors can be made less likely to occur when reading a one-dimensional code or a two-dimensional code.

In the laminate according to one embodiment of the present invention, the content of the scale-like filler contained in the shielding layer is 4.5 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the resin component. Preferably. As a result, the layered product can impart sufficient strength to the shielding layer while having high shielding properties.

Further, in the laminate according to one embodiment of the present invention, the content of carbon black contained in the shielding layer is 0.5 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the resin component. is more preferable. As a result, a laminate having high shielding properties and clear printability can be obtained.

Further, in the laminate according to one embodiment of the present invention, the resin component contains an acrylic copolymer, the acrylic copolymer has a butyl (meth) acrylate monomer ratio of 1% by weight or more, and a carboxyl group is less than 10% by weight. This makes it possible to impart adhesiveness to the shielding layer.

Further, a laminate according to one embodiment of the present invention is a pressure-sensitive adhesive composition for attaching a laminate for laser marking to an adherend, and contains carbon black, a scale-like filler, and a resin component. is more preferable. As a result, it is possible to produce a laminate that can be adhered to an adherend, on which clear printing can be performed on the surface by using a dark-colored shielding layer with high shielding properties. Therefore, the pressure-sensitive adhesive composition for forming the shielding layer is within the scope of the present invention.

The present invention is not limited to the above-described embodiments, but can be modified in various ways within the scope of the claims, and can be obtained by appropriately combining technical means disclosed in different embodiments. is also included in the technical scope of the present invention.

An embodiment of the invention is described below.
[Preparation of materials]
[acrylic resin]
The acrylic resins used in the coating liquids of the inks A1, A2 and B, Examples 1 to 16, and Comparative Examples 1 to 3 are shown below.
Acrylic resin A: Nikalite H4007K4
Molecular weight Mw: 8000
Acrylic adhesive 1: Nisset SY-2523
Molecular weight Mw: 600,000 Acrylic resin A and acrylic pressure-sensitive adhesive 1 are both products of Nippon Carbide Industry Co., Ltd. Both "Nikalite" and "Nisetsu" are registered trademarks of the same company.

[Polyol]
The polyols used in inks A1, A2 and B are shown below.
Polyol 1: Plaxel L320AL
polycaprolactone polyol
Hydroxyl value: 85 mgKOH/g, molecular weight: Mn2000
Polyol 2: Plaxel 305
polycaprolactone polyol
Hydroxyl value: 305mgKOH/g, molecular weight: Mn500
Polyols 1 and 2 are both products of Daicel Corporation, and "PLAXEL" is a registered trademark of the same company.

[Polyisocyanate]
The polyisocyanates used in the coating liquids of the inks A1, A2 and B, Examples 1 to 16, and Comparative Examples 1 to 3 are shown below.
Polyisocyanate 1: Takenate D-268
Isocyanurate in TDI, NCO% = 7.5%
Polyisocyanate 2: Takenate D-140N
Isocyanurate in IPDI, NCO% = 10.5%
Polyisocyanate 3: Takenate D-140N-60
Isocyanurate in IPDI, NCO% = 8.4%
Polyisocyanate 4: Coronate HK
Polyisocyanate containing isocyanurate of HMDI
NCO % = 20%
Polyisocyanate 5: Coronate L45E
TMP adduct of TDI, NCO% = 7.9%
Polyisocyanates 1 to 3 are all products of Mitsui Chemicals, Inc., and "Takenate" is a registered trademark of that company. Both polyisocyanates 4 and 5 are products of Toray Industries, Inc., and "Coronate" is a registered trademark of the company.

[Pigment]
The pigments used in the coating liquids of inks A1, A2 and B, Examples 1 to 16, and Comparative Examples 1 to 3 are shown below.
Black color base 1: NBK-968 black (manufactured by Nikko Bix Co., Ltd.)
Carbon black content: 15.7% by mass
Black color base 2: NX-591 black (manufactured by Nikko Bix Co., Ltd.)
Carbon black content: 15.7% by mass
White color base 1: NBK-967 White (manufactured by Nikko Bix Co., Ltd.)
Titanium oxide content: 58.5% by mass
Scale-like filler 1: Iriodin 103WNT (manufactured by Merck Ltd.)
Titanium oxide coated mica: 100% by mass
Scale-like filler 2: aluminum paste FD-508H (manufactured by Asahi Kasei Corporation)
Each pigment is obtained as a color base. Therefore, the total content of pigments such as carbon black, titanium oxide, and titanium oxide-coated mica and vehicle was calculated as the solid content.

[Preparation Example 1]
Acrylic resin A, polyol 1, and black color base 1 were mixed with Polyflow No. 1 in the amounts shown below. 85HF was mixed and then diluted with ethyl acetate to a solids content of 30% by weight. Ink A1 for the laser absorption layer (second layer) was thus obtained.
Acrylic resin A: 50.0 parts by mass Polyol 1: 50.0 parts by mass Polyisocyanate 1: 12.0 parts by mass Black color base 1: 22.4 parts by mass Polyflow No. 85HF: 2.8 parts by mass Polyflow No. 85HF (manufactured by Kyoeisha Chemical Co., Ltd.) is an acrylic leveling agent.

[Preparation Example 2]
Ethyl acetate was mixed with Silysia 445 in the amounts shown below, and then acrylic resin A, polyol 1, polyisocyanate 1, polyisocyanate 2, black color base 1, and white color base 1 were mixed. After mixing, the mixture was diluted with ethyl acetate so that the solid content was 30% by mass. This gave ink A2 for the laser marking layer (first layer). Silicia 445 (manufactured by Fuji Silysia Chemical Co., Ltd.) is silica.
Sylysia 445: 22.6 parts by mass Acrylic resin A: 70.0 parts by mass Polyol 1: 30.0 parts by mass Polyisocyanate 1: 5.2 parts by mass Polyisocyanate 2: 7.7 parts by mass Black color base 1: 5.2 Part by mass White color base 1: 45.2 parts by mass

[Preparation Example 3]
Polyflow No. 1 was added to ethyl acetate at the contents shown below. 85HF, BYK-370, Sylysia 445 were mixed, then acrylic resin A, polyol 2, polyisocyanate 3, polyisocyanate 4, white color base 1 were mixed. After mixing, the mixture was diluted with ethyl acetate so that the solid content was 55% by mass, and ink B was obtained. BYK-370 (manufactured by Big Chemie Japan Co., Ltd.) is an OH group-containing silicone.
Polyflow No. 85HF: 3.8 parts by mass BYK-370: 4.6 parts by mass Silysia 445: 30.6 parts by mass,
Acrylic resin A: 80 parts by mass Polyol 2: 20 parts by mass Polyisocyanate 3: 36.0 parts by mass Polyisocyanate 4: 16.8 parts by mass White color base 1: 232.3 parts by mass

[Preparation Examples 4 to 23 (Examples 1 to 16 and Comparative Examples 1 to 3)]
Coating liquid compositions of Examples 1 to 16 and Comparative Examples 1 to 3 having the compositions shown in Table 2 were prepared by the following procedure. The resin component amounts of acrylic adhesive 1, polyisocyanate 5, rosin ester, and black color base 2 shown in Table 2 are based on the solid content described in the section of preparation of materials above, and the amount of resin components other than pigments. amount was calculated.

A rosin ester was dissolved in ethyl acetate, and the scale-like filler 1, the acrylic pressure-sensitive adhesive 1, and the black color base 2 were mixed and stirred in this order, and then the polyisocyanate 5 was mixed and stirred. Thereafter, the solid content was adjusted to 30% by mass with ethyl acetate to obtain a coating liquid composition of Example 1. Coating liquid compositions of Examples 2 to 16 and Comparative Examples 1 to 3 were prepared in the same manner. Pencel D-125 (Tg=125° C., manufactured by Arakawa Chemical Industries, Ltd.) was used as the rosin ester, and flake-like filler 2 was used in Example 16.

[Preparation of film layer]
Both surfaces of PET film S-50 (manufactured by Unitika Ltd.) were subjected to corona treatment. Ink A1 was applied to one surface of the PET film so that the film thickness after drying was 2 μm, and dried at 100° C. for 1 minute to form ink layer A1. Next, the ink A2 was applied on the ink layer A1 so that the film thickness after drying was 2 μm, and dried at 100° C. for 1 minute to form the ink layer A2. Subsequently, it was cured at 40°C for 3 days. On the coating film A2 obtained by curing the ink layer A1 and the ink layer A2, the ink B is applied so that the film thickness after drying is 15 μm, dried at 150° C. for 1 minute, An ink layer B was formed. After that, it was cured at 60° C. for 3 days to obtain a film layer in which the PET film, the coating film A1, the coating film A2, and the coating film B were laminated in this order.

[Preparation of Laminate for Laser Marking]
The coating solution of Example 1 was prepared by mixing the materials at the composition ratio shown in Table 1 and adjusting the solid content concentration to 30% by weight with ethyl acetate. and dried at 100°C for 1 minute. After drying, a layer formed from the coating liquid was laminated on the opposite side of the film layer to the side on which each coating film was formed to obtain a laminate for laser marking. After that, the laminate for laser marking was aged for one week under conditions of 23° C./50% RH.

[Evaluation of short-wavelength laser printability]
The short wavelength laser printability was evaluated with a fiber laser marker LP-Z130 (manufactured by Panasonic Corporation). The short-wavelength laser printability was evaluated under the basic conditions of an output of 75%, a pulse period of 50 Hz, a line width of 0.07 mm, and a scanning speed of 2000 mm/sec. As an evaluation by changing the output, short wavelength laser printability was evaluated for each output corresponding to 135%, 120%, 100%, 80%, 60% and 40% of the output under the basic conditions. As an evaluation by changing the scanning speed, evaluation was performed for each condition of 2000 mm/sec, 1600 mm/sec, 1200 mm/sec, 800 mm/sec and 400 mm/sec. In addition, as an evaluation by changing the pulse period, evaluation was made for each condition of the pulse period of 50 Hz and 30 Hz. The number of times of printing was changed to 1 time and 2 times, and the letter "A" was printed. After that, the number of prints (those with a distinct hue difference from the surface layer) and the number of penetrations were each divided by the total number for evaluation. At this time, the number of penetrating parts is not included in the number of printed parts.
Print Evaluation SS: The rate of successful printing is 70% or more.
S: The percentage of successful printing is 60% or more and less than 70%.
A: The ratio of successful printing is 50% or more and less than 60%.
B: The percentage of successful printing is 40% or more and less than 50%.
C: 30% or more and less than 40% of successful printing.
D: Less than 30% of successful printing.
Penetration Evaluation S: Percentage of penetration is less than 30%.
A: The penetration rate is 30% or more and less than 40%.
B: The penetration rate is 40% or more and less than 50%.
C: The penetration rate is 50% or more and less than 60%.
D: The penetration rate is 60% or more.

[Evaluation of CO ₂ laser printability]
With a CO ₂ laser marker ML-Z9510 (manufactured by Keyence Corporation), the output is 20%, 30%, 40%, 50%, 60%, 70%, 80%, the scanning speed is 100 mm / sec, 200 mm / sec, 300 mm/sec, 400 mm/sec, 500 mm/sec, 600 mm/sec, 700 mm/sec, 800 mm/sec, 900 mm/sec, and 1000 mm/sec. . After that, the number of prints (those with a distinct hue difference from the surface layer) and the number of penetrations were each divided by the total number for evaluation. At this time, the number of penetrating parts is not included in the number of printed parts.
Printing evaluation SS: The ratio of successful printing is 50% or more.
S: 40% or more and less than 50% of successful printing.
A: The ratio of successful printing is 30% or more and less than 40%.
B: The percentage of successful printing is 20% or more and less than 30%.
C: The percentage of successful printing is 10% or more and less than 20%.
D: Less than 10% of successful printing.
Penetration evaluation S: Percentage of penetration is less than 10%.
A: The penetration rate is 10% or more and less than 15%.
B: The penetration rate is 15% or more and less than 20%.
C: The penetration rate is 20% or more and less than 40%.
D: The penetration rate is 40% or more.

[Evaluation of adhesive strength]
The laminates for laser marking formed using the coating liquids of Examples 1 to 16 and Comparative Examples 1 to 3 were each cured for one week under conditions of 23° C./50% RH. After curing, a sample of 10 mm in width and 150 mm in length was cut out of each laminate for laser marking. After that, the sample was pasted on various adherends with a 2 kg roller at 20 mm/sec one reciprocation, and after 24 hours, the measurement length was set to 100 mm, and the adhesive strength was measured when pulled at an angle of 180° at a speed of 300 mm/min. did.

〔Evaluation results〕
In the laminates of Examples 1 to 16, the evaluation was performed by changing the carbon black content from 0.8 parts by mass to 4.2 parts by mass with respect to 100 parts by mass of the resin component. However, in the laminates of Examples 1 to 16 in which carbon black and titanium oxide-coated mica are used in combination, the printability and penetration resistance (shielding properties) of each laser beam are expected to easily absorb these lights. It was not found to show a linear (first-order) relationship with the carbon black content. More specifically, when titanium oxide-coated mica is used in combination, the relationship between the carbon black content and the penetration resistance and shielding properties of each laser beam is that the carbon black content is 1.5 to 3.5 parts by mass. It was found that a favorable peak was shown between That is, it is presumed that when the content of carbon black is excessive, the shielding property of titanium oxide-coated mica is canceled, but by using more than 1.5 parts by mass of carbon black, the titanium oxide-coated mica It was confirmed that the shielding effect was enhanced. In addition, it was confirmed that the laminates of Comparative Examples 1 to 3 were particularly inferior in light-shielding properties (shielding properties) of laser light.

INDUSTRIAL APPLICABILITY The present invention can be suitably used, for example, for displaying product information (manufacturing number, lot number, etc.) in industrial products.

1 shielding layer 1′ shielding layer 1″ shielding layer 3 laser marking layer (first layer)
3' laser marking layer (first layer)
5 adhesive layer 100 laminate (laminate for laser marking)
101 laminate (laminate for laser marking)
102 Laminate (laminate for laser marking)
103 Laminate (laminate for laser marking)
B Laser light

Claims (5)

A laminate for laser marking,
a shielding layer having a shielding property against laser light;
and a laser marking layer,
The shielding layer is a laminate containing a resin component, carbon black, and a scale-like filler. The laminate according to claim 1, wherein the scale-like filler is titanium oxide-coated mica. The laminate according to claim 1 or 2, wherein the content of the scale-like filler contained in the shielding layer is 4.5 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the resin component. . The content of carbon black contained in the shielding layer is 0.5 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the resin component, according to any one of claims 1 to 3. laminate. The resin component contains an acrylic copolymer,
Claims 1 to 4, wherein the acrylic copolymer has a ratio of butyl (meth)acrylate monomers of 80% by mass or more and a ratio of (meth)acrylic monomers having a carboxyl group of 10% by mass or less. The laminate according to any one of the above.

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