JP2011020374A - Alteration prevention label - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an alteration prevention label, which is a laser markable label to be pasted on an object and then peeled off, and in which fluorescence remains on the peeled area even after cleanly peeled off without breakage, which is easy to occur when the base material sheet is fragile when peeled off, and fluorescence still remains even after wiped off. <P>SOLUTION: The alteration prevention label is a laser markable label having an adhesion layer on a white layer side of a laminated base material sheet having a black layer on which information recording is made through laser beam irradiation and a white layer thereunder. The adhesion layer features containing fluorescent dye and titanium dioxide particles. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a tamper-proof label. More specifically, the present invention is a laser marker label comprising a laminated sheet having a base material having a black layer on which information can be recorded by laser light irradiation and a white layer underneath, and is provided on the white layer side. By adding a fluorescent dye and titanium dioxide particles to the pressure-sensitive adhesive layer, it is easy to break when the substrate laminate sheet is brittle when the label is attached to the adherend and then peeled off. The present invention relates to a tamper-proof label in which the fluorescence remains on the peeled off mark of the adherend even if it is peeled cleanly without being damaged, and the fluorescence still remains after wiping.

In order to ensure safety in product use as automobile parts, electrical / electronic parts, precision machine parts, etc. have become smaller, higher density, higher performance in recent years, or through the enforcement of the PL Law, It has become necessary to display features and precautions for handling on each part and product. In this case, the display content must be prevented from being tampered with, and therefore, a tamper-proof label or the like is used.
Also, when consigning or packing an article, if it cannot be prevented with a lock or the like to prevent unfair unpacking of the article or opening of the lid, the opening is usually made with a tamper-proof tape or the like. Sealing is done. For example, when transporting a safety box such as a desk, a cupboard, a safe, or baggage, a tamper-proof tape or a seal is generally affixed to the outside of the drawer, door, lid, or the like.

On the other hand, adhesive labels for sealing are often used for the purpose of proof of products and sealing. However, illegal actions such as once peeling off the sealing label and modifying the contents or replacing the contents and then sealing again with the same label are problematic. For this reason, a tamper-proof label is used in order to prevent unfair label reattachment and reuse.
As such security members such as anti-counterfeiting and tamper-proof labels, tapes, seals, etc., for example, when the member is peeled off from the adherend, the type in which the base material is destroyed, or the peeled trace remains on the adherend. The type is known.
Furthermore, in recent years, laser marker labels that record information by irradiation with laser light have been actively used as information recording labels. For example, in the automobile field, it is used for an automobile VIN (body number) label, an anti-theft label, a caution label, and the like.

In Patent Document 1, as a label for preventing counterfeiting, the fluorescent dye is uniformly dispersed in the pressure-sensitive adhesive layer, so that the fluorescent dye migrates and remains on the surface of the object to be pasted after the label is peeled off. In the daylight, the remaining fluorescent dye is not visible, but when irradiated with ultraviolet rays, the anti-counterfeit label has a fluorescence corresponding to the shape of the peeled label and proves that the label has been attached. It is disclosed.
However, this technique has a drawback that the fluorescent dye is easily removed by wiping.
In Patent Document 2, it is not possible to peel off the adherend and reuse it, and it is not necessary to incorporate a security mark to prevent reuse or counterfeiting. An anti-counterfeit label that can be applied to is disclosed. However, this anti-counterfeit label is a technology that uses the brittleness of the layers constituting the label, and is not a forgery-preventing technology based on the footprinting effect that leaves a peeled mark on the adherend.

JP-A-1-13579 JP 2008-90063 A

  The present invention has been made under such circumstances, and is a laser marker label. When the label is attached to an adherend and then peeled off, the substrate sheet is easily damaged if it is brittle. An object of the present invention is to provide a tamper-proof label in which the fluorescence remains on the peeled-off mark of the adherend even if it is peeled cleanly without being damaged, and the fluorescence still remains after wiping.

As a result of intensive studies to achieve the above object, the present inventor has obtained the following knowledge.
By using a laminated sheet having a black layer on which information can be recorded by laser light irradiation and a white layer underneath as a substrate, it can be used as a laser marker label, and the laminated sheet is brittle In the case of a sheet, it was found that it is effective as a tamper-proof label because it is easily damaged when peeled off after being attached to an adherend.
Furthermore, even if the adhesive layer provided on the white layer side contains titanium dioxide particles together with a fluorescent dye, the label affixed to the adherend can be removed cleanly without damaging the base sheet, for example. It was found that the fluorescence remained on the peeled off mark of the adherend, and that the fluorescence remained even after wiping, and that this fluorescence could be clearly seen by irradiating with ultraviolet rays even though it was not visible to the naked eye. .
The present invention has been completed based on such findings.

That is, the present invention
(1) A laser marker label having a pressure-sensitive adhesive layer on the white layer side of a laminated substrate sheet having a black layer capable of recording information by laser light irradiation and a white layer thereunder, wherein the pressure-sensitive adhesive A tamper-proof label, wherein the layer comprises titanium dioxide particles together with a fluorescent dye,
(2) The tamper-proof label according to (1) above, wherein the titanium dioxide particles are rutile type having an average particle size of 0.05 to 10 μm,
(3) The above (1) or (2), wherein the laminated base sheet is a brittle sheet containing at least one resin selected from an acrylic resin, an acrylic urethane resin and a urethane resin as a matrix resin. ) Tamper-proof label according to paragraph
(4) Tamper prevention according to any one of (1) to (3) above, wherein the thickness of the black layer in the laminated substrate sheet is 5 to 30 μm and the thickness of the white layer is 50 to 200 μm. For labels,
(5) The tamper-proof label according to any one of (1) to (4) above, wherein the pressure-sensitive adhesive layer is a cross-linked acrylic pressure-sensitive adhesive layer, and (6) information is recorded on the black layer The tamper-proof label according to any one of the above (1) to (5), wherein the laser beam to be used is from a carbon dioxide laser oscillator,
Is to provide.

  According to the present invention, the substrate is a laser marker label comprising a laminated sheet having a black layer on which information can be recorded by laser light irradiation and a white layer under the black layer, and the adhesive provided on the white layer side By including a fluorescent dye and titanium dioxide particles in the agent layer, when the label is affixed to an adherend and then peeled off, the laminated substrate sheet is fragile, but is likely to be damaged. Even if it is peeled off cleanly, the tamper-proof label can be provided in which the fluorescence remains on the trace of the adherend peeled off, and the fluorescence still remains after wiping.

It is a cross-sectional schematic diagram which shows the structure of an example of the label for tampering prevention of this invention. It is a cross-sectional schematic diagram of an example which shows the state which irradiated the laser beam to the tamper-proof label of this invention, and showed the state which cut and printed the printed label.

  The tamper-proof label of the present invention is a laser marker label having a pressure-sensitive adhesive layer on the white layer side of a laminated base sheet having a black layer capable of recording information by laser light irradiation and a white layer under the black layer. And the said adhesive layer contains a titanium dioxide particle with a fluorescent dye, It is characterized by the above-mentioned.

[Laminated substrate sheet]
The base sheet used for the tamper-proof label of the present invention (hereinafter sometimes simply referred to as the label of the present invention) is a laminated sheet having a black layer and a white layer underneath, as a matrix resin. A brittle sheet containing at least one resin selected from acrylic resins, acrylic urethane resins, and urethane resins is preferable.
If the base sheet is such a brittle sheet, after the label of the present invention is applied to the adherend, it is easy to break even if the label is peeled off, making it difficult to peel off effectively and preventing tampering. Is.

(Acrylic resin brittle sheet)
There is no restriction | limiting in particular as an acrylic resin-type brittle sheet, (B) Fused silica, water with respect to a conventionally well-known thing, for example (A) 100 mass parts of acrylic resins whose elongation at break is about 10 to 180%. Resin composition I containing about 10 to 70 parts by mass of at least one inorganic filler selected from aluminum oxide, barium sulfate, calcium carbonate, titanium dioxide and the like and (C) about 0 to 30 parts by mass of a plasticizer. A sheet formed by forming a film can be used.
As said fused silica, what has a particle size of 0.5-100 micrometers normally, Preferably it is 1-70 micrometers is used. Moreover, it is preferable to have an average particle diameter of 5 to 20 μm. Furthermore, it is preferable that the particle size distribution is wide. Those having an average particle size of less than 5 μm have poor dispersibility when preparing a dispersion of the resin composition for a brittle sheet used in the present invention, while those having an average particle size of more than 20 μm are smooth on the surface of the resulting brittle sheet. May decrease. Those containing many particles having a particle size of less than 0.5 μm have poor dispersibility when preparing the dispersion, and the dispersion tends to have high viscosity. On the other hand, a sheet containing many particles having a particle size exceeding 100 μm has a rough surface.

  As aluminum hydroxide and barium sulfate, those having a particle size of usually 0.2 to 50 μm, preferably 0.7 to 30 μm are used. Moreover, it is preferable to have an average particle diameter of 1 to 20 μm. Those having an average particle size of less than 1 μm have poor dispersibility when preparing a dispersion of the resin composition I for a brittle sheet used in the present invention, while those having an average particle size of more than 20 μm There is a risk of reducing the sex. Those containing many particles having a particle size of less than 0.2 μm have poor dispersibility when preparing the dispersion, and the dispersion tends to have high viscosity. On the other hand, a sheet containing many particles having a particle size exceeding 50 μm has a rough surface.

  Further, calcium carbonate having a particle size of 0.1 to 50 μm, preferably 0.2 to 30 μm, as measured by a sedimentation turbidity method, is used. Moreover, it is preferable to have an average particle diameter of 0.5 to 20 μm. When the average particle size is less than 0.5 μm, the dispersibility in the dispersion solution is poor, and when the average particle size exceeds 20 μm, the smoothness of the sheet surface may be lowered. Those containing many particles having a particle size of less than 0.1 μm have poor dispersibility in the dispersion and the dispersion tends to have high viscosity, while those containing many particles having a particle size of more than 50 μm have a sheet surface. It will be rough. As calcium carbonate, any of precipitated calcium carbonate, heavy calcium carbonate, and light calcium carbonate may be used.

There are three types of titanium dioxide: anatase type, brookite type and rutile type, and the photocatalytic ability is the highest in the anatase type and the lowest in the rutile type. When titanium dioxide particles having a high photocatalytic ability are contained in the organic layer, the deterioration of the organic layer is accelerated by the photocatalytic ability. Therefore, it is preferable to use rutile type titanium dioxide particles that are usually used as white pigments. In particular, when whiteness is required, the use of rutile titanium dioxide particles is optimal as the inorganic filler.
As the titanium dioxide particles, those having an average particle diameter of about 0.05 to 10 μm are usually used.

The acrylic resin having an elongation at break of the component (A) of about 10 to 180% is preferably one having an elongation at break of 20 to 150%. With an acrylic resin having an elongation at break exceeding 10 to 180%, it is difficult to obtain a brittle sheet having a desired elongation at break. The elongation at break was adjusted for normal conditions by leaving the sample at 22 to 25 ° C. for 1 hour or longer, and then for a strip type test piece having a size of 20 × 100 mm, a tensile speed of 5 mm / min and a chart speed of 100 mm / This is a value obtained by performing an Instron-type tensile test 6 times under the conditions of a minute and a chuck interval of 50 mm, and calculating an average value of elongation.
Preferred examples of the acrylic resin include (1) methyl methacrylate / methyl acrylate / butyl acrylate / styrene copolymer alone, (2) methyl methacrylate / methyl acrylate copolymer and methyl methacrylate / styrene / butyl acrylate copolymer. Examples thereof include a mixture with coalescence.

In this invention, content of the inorganic filler of (B) component is normally selected in the range of 10-70 mass parts with respect to 100 mass parts of acrylic resin of (A) component. If this amount is less than 10 parts by mass, the brittleness of the sheet is insufficient, and if it exceeds 70 parts by mass, the sheet becomes too brittle more than necessary, and the handleability deteriorates. In view of brittleness and handleability of the sheet, the preferable content of the inorganic filler is in the range of 20 to 50 parts by mass with respect to 100 parts by mass of the acrylic resin.
In the brittle sheet, since the resin component is an acrylic resin, it is not necessary to use a plasticizer forcibly, but a plasticizer may be used as the component (C) in order to impart appropriate flexibility to the sheet. Good. The plasticizer is not particularly limited, and can be arbitrarily selected from those conventionally used for acrylic resins. Examples of the plasticizer include those having good compatibility with the acrylic resin of component (A), such as alkyl benzyl phthalates such as octyl benzyl phthalate and myristyl benzyl phthalate; dialkyl phthalates such as dibutyl phthalate, dihexyl phthalate and dioctyl phthalate; Phosphate esters such as dil phosphate and trioctyl phosphate; Fatty acid esters such as dibutyl sebacate and acetyl tributyl citrate; Polyesters such as adipic acid polyester, sebacic acid polyester and phthalic acid polyester; Diethylene glycol dibenzoate and dipropylene Glycol derivatives such as glycol dibenzoate, triethylene glycol di (2-ethylhexoate); glycerol triacetate, Glycerin derivatives such as Se roll tributyrate; and epoxy derivatives such as epoxidized soybean oil.
In the present invention, these plasticizers may be used alone or in combination of two or more, and the content thereof is 100 parts by mass of the acrylic resin of the component (A). The range of 0-30 mass parts is preferable. When this content exceeds 30 parts by mass, the sheet becomes too soft, the brittleness is lowered, and the object of the present invention cannot be achieved. From the viewpoints of the film formability of the dispersion solution, moderate flexibility of the sheet, and brittleness, the preferred content of this plasticizer is in the range of 0 to 20 parts by mass with respect to 100 parts by mass of the acrylic resin.

(Acrylic urethane resin brittle sheet)
There is no restriction | limiting in particular as an acrylic urethane resin-type brittle sheet, It consists of a conventionally well-known thing, for example, (x-1) acrylic urethane resin 30-70 mass%, and (x-2) acrylic resin 70-30 mass%. (X) The sheet | seat formed by forming resin composition II containing about 10-100 mass parts of (Y) inorganic fillers per 100 mass parts of resin components can be used.
The acrylic urethane resin as the component (x-1) can be obtained by polymerizing a vinyl group-containing urethane polymer and a (meth) acrylic monomer.
Examples of the vinyl group-containing urethane polymer include organic diisocyanate compounds, high molecular weight polyols, vinyl compounds having one or more active hydrogens and one or more radical polymerizable double bonds in the same molecule, and chain extension as necessary It can be obtained by reacting an agent.
The vinyl group-containing urethane polymer preferably contains 1 to 200 equivalents / 1000 kg of radical polymerizable double bonds, and more preferably 10 to 100 equivalents / 1000 kg. If the double bond content is too small, the copolymerization amount of the (meth) acrylic monomer is reduced, the compatibility between the urethane polymer and the (meth) acrylic polymer is lowered, and the stability of the resin composition II for the brittle sheet is reduced. It worsens and the film properties become poor. In addition, if the double bond content is too large, the ratio of the bifunctional urethane polymer in the reaction increases, and it tends to be three-dimensional during radical polymerization of the vinyl group-containing urethane polymer and the (meth) acrylic monomer. . The weight average molecular weight of the vinyl group-containing urethane polymer is usually about 10,000 to 200,000.

Examples of the (meth) acrylic monomer to be polymerized with the vinyl group-containing urethane polymer include acrylic acid esters such as methyl acrylate, ethyl acrylate, n- or isobutyl acrylate, hexyl acrylate, cyclohexyl acrylate, lauryl acrylate and stearyl acrylate; acrylic acid; Methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, n- or isobutyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, lauryl methacrylate, stearyl methacrylate; methacrylic acid; and the like can be used. This (meth) acryl monomer can also be used as a mixture of two or more.
Further, if necessary, another vinyl group-containing compound can be used in combination with the (meth) acrylic monomer. As other vinyl group-containing compounds, styrene, methylstyrene, vinyl acetate, acrylonitrile, maleic anhydride, and the like can be used. Furthermore, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, aminoethyl methacrylate, caprolactone adduct of 2-hydroxyethyl acrylate, caprolactone adduct of 2-hydroxy methacrylate, etc. can be used in combination with the (meth) acrylic monomer. it can.
Polymerization of the vinyl group-containing urethane polymer and the (meth) acrylic monomer is performed by adding a polymerization initiator in an organic solvent under an inert gas stream such as nitrogen and heating by a normal solution polymerization method.
The acrylic urethane resin of the component (x-1) thus obtained has an elongation at break of about 10 to 180% as in the case of the (A) acrylic resin in the acrylic resin brittle sheet described above. Is preferable, and 20 to 150% is more preferable.

In the resin composition II, the acrylic resin used as the component (x-2) is a resin having a (meth) acrylic acid ester unit as a main component, and even a homopolymer consisting only of a (meth) acrylic acid ester unit can be used. It may be a polymer, or may be a copolymer of a (meth) acrylic acid ester and a monomer copolymerizable therewith.
The acrylic resin used for the component (x-2) preferably has an elongation at break in the range of 1 to 30%, and more preferably in the range of 10 to 25%.
When the elongation at break is within the above range, a brittle film having a desired elongation at break can be easily obtained.
The molecular weight of the acrylic resin is not particularly limited, but is usually 50,000 to 500,000 in terms of weight average molecular weight.

In the resin composition II, the (X) resin component composed of 30 to 70% by mass of the (x-1) component and 70 to 30% by mass of the (x-2) component is used. When the (x-1) component is more than the above range, the brittleness becomes insufficient, and conversely, when the (x-1) component is less than the above range, the workability deteriorates. (X) As a resin component, what consists of 35-65 mass% of (x-1) component and 65-35 mass% of (x-2) component is preferable.
In the said resin composition II, it is preferable to contain 10-100 mass parts of (Y) inorganic fillers with respect to 100 mass parts of (X) resin components of the said ratio. If the content of the inorganic filler is less than 10 parts by mass, the brittleness of the resulting sheet is insufficient, and if it exceeds 100 parts by mass, the sheet becomes too brittle than necessary, and the handleability deteriorates. The content of the component (Y) is preferably 40 to 95 parts by mass and more preferably 60 to 90 parts by mass with respect to 100 parts by mass of the component (X).
The inorganic filler of component (Y) is as described as the inorganic filler of component (B) in the acrylic resin brittle sheet described above.

(Urethane resin brittle sheet)
There is no restriction | limiting in particular as a urethane-resinous brittle sheet, For example, (D) thermoplastic urethane-type resin, and resin containing about 10-70 mass parts of (E) inorganic fillers per 100 mass parts A sheet formed by forming a film of the composition III can be used.
Examples of the thermoplastic urethane resin (D) include long-chain polyols such as poly (oxytetramethylene) glycol, poly (oxypropylene) glycol, and poly (ethylene adipate) glycol, short-chain polyols as chain extenders, and organic diisocyanates. Urethane resins obtained by reacting compounds can be used. As with the acrylic resin, the elongation at break of the urethane resin is preferably about 10 to 180%, more preferably 20 to 150%.
In addition, the kind and quantity of the inorganic filler of (E) component are as having demonstrated as the inorganic filler of (B) component in the above-mentioned acrylic resin brittle sheet.

The resin composition I, the resin composition II, and the resin composition III described above may include an ultraviolet absorber, an antioxidant, a light stabilizer, and an antistatic agent as long as the object of the present invention is not impaired. A flame retardant and the like can be appropriately contained.
In the tamper-proof label of the present invention, a laminated sheet having a black layer and a white layer therebelow is used as the base sheet.

(Black layer)
In the present invention, the black layer in the laminated base sheet is a layer on which information can be recorded by laser light irradiation, and is black on the resin composition I, resin composition II and / or resin composition III described above. It can form by forming into a film the resin composition Z which mix | blended the system pigment.
In this black layer, as the inorganic filler in the resin composition I, resin composition II and / or resin composition III to be used, it is not necessary to use titanium dioxide, and fused silica, aluminum hydroxide, barium sulfate, etc. Can be used.
The black pigment is preferably carbon black having an average particle diameter of preferably 10 to 50 nm, more preferably 20 to 50 nm, and a specific surface area of preferably 70 to 150 m ² / g. This carbon black includes channel black, furnace black, acetylene black, thermal black, etc., depending on the production method, and any of them can be used.
In the present invention, if necessary, in addition to the carbon black, black organic pigments such as black chromium oxide, titanium black, black iron oxide, or aniline black, and further red, blue, green, purple, yellow, cyan, A mixed color organic pigment obtained by mixing at least two kinds of organic pigments selected from magenta and pseudo-blackening can be used in combination.
The blending amount of the black pigment is usually 1 to 80 parts by mass, more preferably 1 to 50 parts, with respect to 100 parts by mass of the resin component in the resin composition Z, from the viewpoints of laser light absorption and film forming properties. It is 5 mass parts, More preferably, it is 5-20 mass parts.
The thickness of this black layer is usually about 5 to 30 μm, preferably about 10 to 20 μm.

(White layer)
In the present invention, the white layer in the laminated base sheet is a layer provided below the black layer described above, and the irradiated portion of the black layer is removed by laser light irradiation, and the information is white on the black layer. It is a layer for recording.
This white layer can be formed by forming the resin composition W using the resin composition I, the resin composition II and / or the resin composition III described above.
In this case, since whiteness is required, as the inorganic filler in the resin composition I, resin composition II and / or resin composition III or resin composition II, rutile-type titanium dioxide particles having high whiteness Is preferably used.
The thickness of this white layer is usually about 50 to 200 μm, preferably about 60 to 100 μm.

(Preparation of laminated base sheet)
The production method of the laminated base sheet in the tamper-proof label of the present invention is not particularly limited, and can be formed by any method such as a casting method, an extrusion method, a calendar method, etc. Among them, the casting method is preferable particularly from the viewpoints of productivity and sheet quality.
Specifically, as the resin composition Z, after preparing a homogeneous dispersion containing each component, this is applied on a process sheet having peelability to a predetermined dry thickness, A black layer is formed by heating and drying at about 80 to 180 ° C. Next, after preparing a homogeneous dispersion containing each component as the resin composition W, this is coated on the black layer so as to have a predetermined dry thickness, and is about 80 to 180 ° C. By forming by heating and drying to form a white layer, a laminated base sheet composed of a black layer and a white layer is formed on the process sheet. By peeling off the process sheet, the laminated base sheet is produced. Can do. As the solvent used in this case, a solvent that dissolves the resin component and has a boiling point of about 80 to 180 ° C. is preferable. Examples of such a solvent include aromatic hydrocarbons such as toluene, xylene, ethylbenzene, and trimethylbenzene, ketones such as methyl ethyl ketone, diisobutyl ketone, and cyclohexanone, and dimethylformamide. These may be used alone or in combination of two or more. The amount of the solvent used in this casting method is usually 100 to 400 parts by mass, preferably 150 to 350 parts by mass with respect to 100 parts by mass of the resin component.

[Adhesive layer]
In the tamper-proof label of the present invention, the pressure-sensitive adhesive layer is provided on the white layer side of the laminated base sheet produced as described above.
In the present invention, the pressure-sensitive adhesive layer needs to contain titanium dioxide particles together with the fluorescent dye.
Examples of the fluorescent dye include dyes that absorb ultraviolet rays and emit fluorescence, such as diaminostilbene, quinazolone, perylene, coumarin, oxazole, triazole, carbazole, pyridine, naphthalic acid, imidazolone dye, Fluorescent agents such as fluorescein, thioflavine, eosin, rhodamine and terphenyl.
These may be used individually by 1 type and may be used in combination of 2 or more type. The content of the fluorescent dye in the pressure-sensitive adhesive layer is usually about 0.1 to 30 parts by weight, preferably 0 with respect to 100 parts by weight of the solid content of the pressure-sensitive adhesive, from the viewpoint of the balance between fluorescence emission and economy. It is 0.3-10 mass parts, More preferably, it is 0.5-5 mass parts.

On the other hand, as the titanium dioxide particles, it is preferable to contain rutile type titanium dioxide particles having an average particle diameter of about 0.05 to 10 μm for the reason described above.
By using the fluorescent dye and titanium dioxide particles in combination, the mechanism is not necessarily clear. For example, when the tamper-proof label of the present invention is applied to the adherend and then peeled off, the adherend is peeled off. Although fluorescence remains on the traces, there is an effect that the fluorescence remains even after wiping with a cloth soaked with a solvent.
If only the fluorescent dye is used without adding titanium dioxide, the wiping operation eliminates the residual fluorescence. The content of titanium dioxide particles in the pressure-sensitive adhesive layer is preferably. It is 0.1-50 mass parts, More preferably, it is 0.3-50 mass parts, More preferably, it is 0.5-30 mass parts.

There is no restriction | limiting in particular as an adhesive which forms the said adhesive layer, Arbitrary things can be suitably selected and used from what is conventionally used for the adhesive layer of the adhesive sheet for marking. For example, an acrylic adhesive, a rubber adhesive, a silicone adhesive, a polyurethane adhesive, a polyester adhesive, and the like can be used. These pressure-sensitive adhesives may be emulsion type, solvent type, or solventless type. The thickness of the pressure-sensitive adhesive layer is usually 1 to 200 μm, preferably about 5 to 100 μm.
Among the various pressure-sensitive adhesives, acrylic pressure-sensitive adhesives are preferable from the viewpoint of weather resistance and the like.

(Acrylic adhesive)
The pressure-sensitive adhesive layer formed using the acrylic pressure-sensitive adhesive includes an acrylic resin having a weight average molecular weight of about 500,000 to 2,000,000, preferably 700,000 to 1,700,000, and is made of a crosslinked acrylic pressure-sensitive adhesive. A layer is preferred. When the weight average molecular weight is in the above range, a tamper-proof label having a balance between adhesive force and holding force can be obtained.
In addition, the said weight average molecular weight is the value of polystyrene conversion measured by the gel permeation chromatography (GPC) method.

<Acrylic resin>
As the acrylic resin contained in the acrylic pressure-sensitive adhesive, a (meth) acrylic acid ester copolymer is used. As this (meth) acrylic acid ester-based copolymer, the alkyl group of the ester part has a (meth) acrylic acid ester having 1 to 20 carbon atoms, a monomer having a functional group having active hydrogen, and, if desired, Preferred examples include copolymers with other monomers used.
Here, examples of the (meth) acrylic acid ester having 1 to 20 carbon atoms of the alkyl group in the ester portion include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, (meth ) Butyl acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, decyl (meth) acrylate, Examples include dodecyl (meth) acrylate, myristyl (meth) acrylate, palmityl (meth) acrylate, stearyl (meth) acrylate, and the like. These may be used alone or in combination of two or more.

  On the other hand, examples of the monomer having a functional group having active hydrogen include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, (meth) (Meth) acrylic acid hydroxyalkyl esters such as 2-hydroxybutyl acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate; acrylamide, methacrylamide, N-methylacrylamide, N-methyl Acrylamides such as methacrylamide, N-methylolacrylamide, N-methylolmethacrylamide; monomethylaminoethyl (meth) acrylate, monoethylaminoethyl (meth) acrylate, monomethylaminopropyl (meth) acrylate, (meth) acrylic Acids such as monoethylaminopropyl ( Data) acrylate monoalkyl aminoalkyl, acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, ethylenically unsaturated carboxylic acids such as citraconic acid. These monomers may be used independently and may be used in combination of 2 or more type.

Examples of other monomers used as desired include vinyl esters such as vinyl acetate and vinyl propionate; olefins such as ethylene, propylene and isobutylene; halogenated olefins such as vinyl chloride and vinylidene chloride; styrene Styrene monomers such as α-methylstyrene; diene monomers such as butadiene, isoprene and chloroprene; nitrile monomers such as acrylonitrile and methacrylonitrile; N, N-dimethylacrylamide, N, N— And N, N-dialkyl-substituted acrylamides such as dimethylmethacrylamide. These may be used alone or in combination of two or more.
In the acrylic pressure-sensitive adhesive, the (meth) acrylic acid ester copolymer used as a resin component is not particularly limited with respect to the copolymerization form, and may be any of random, block, and graft copolymers. .
In the present invention, this (meth) acrylic acid ester copolymer may be used alone or in combination of two or more.

<Crosslinking agent and other additive components>
The acrylic pressure-sensitive adhesive is preferably subjected to a crosslinking treatment, and the crosslinking agent used for the crosslinking treatment is not particularly limited, and any one of those conventionally used as a crosslinking agent in an acrylic pressure-sensitive adhesive can be arbitrarily selected. Those can be appropriately selected and used. Examples of such a crosslinking agent include polyisocyanate compounds, epoxy compounds, melamine resins, urea resins, dialdehydes, methylol polymers, metal chelate compounds, metal alkoxides, metal salts, and the like. Is preferably used.
In this invention, this crosslinking agent may be used individually by 1 type, and may be used in combination of 2 or more type. Further, the amount used depends on the kind of the crosslinking agent, but is usually 0.01 to 20 parts by weight, preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the (meth) acrylic ester copolymer. It is selected in the range of mass parts.
In addition, a tackifier, an antioxidant, an ultraviolet absorber, a light stabilizer, a softener, a silane coupling agent, a filler, and the like can be added to the acrylic pressure-sensitive adhesive as desired.

(Formation of adhesive layer)
The method for forming the pressure-sensitive adhesive layer on the white layer side of the laminated base sheet prepared as described above is not particularly limited. For example, the pressure-sensitive adhesive described above is directly applied to the white layer surface with a predetermined dry thickness. It is possible to use a method in which a pressure-sensitive adhesive layer is formed by applying the film so as to have a thickness, heating and drying. In this case, it is preferable to stick a release sheet to the pressure-sensitive adhesive layer so that the surface of the release agent layer is in contact.
Also, apply the adhesive to the release agent layer surface of the release sheet so that the dry thickness is a predetermined thickness, heat and dry to provide an adhesive layer, and then apply this to the white layer surface The pressure-sensitive adhesive layer may be transferred, and the release sheet may be left as it is.
Various methods can be used as the method for forming the pressure-sensitive adhesive layer without any particular limitation. For example, air knife coater, blade coater, bar coater, gravure coater, roll coater, roll knife coater, curtain coater, die coater, knife Examples include coaters, screen coaters, Mayer bar coaters, and kiss coaters.
Any release sheet may be used, for example, films made of various resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene, polypropylene, polyacrylate, polyethylene laminated paper, polypropylene laminated paper, clay coated paper. In addition, various paper materials such as resin-coated paper, glassine paper, and high-quality paper can be used as the base material, and the surface of the base material bonded to the pressure-sensitive adhesive layer can be peeled off if necessary.
Examples of the release treatment include formation of a release agent layer made of a release agent such as a silicone resin, a long-chain alkyl resin, and a fluorine resin. The thickness of the release sheet is not particularly limited and may be appropriately selected.

In this way, the tamper-proof label of the present invention is obtained.
FIG. 1 is a schematic cross-sectional view showing the structure of an example of a tamper-proof label of the present invention. A tamper-proof label 10 is a laminated base material comprising a black layer 1 and a white layer 2 provided thereunder. The pressure-sensitive adhesive layer 3 is provided on the surface of the white layer 2 of the sheet 5, and the release sheet 4 is further stuck on the pressure-sensitive adhesive layer 3.
FIG. 2 is a schematic cross-sectional view of an example showing a state in which a tamper-proof label according to the present invention is printed by irradiating a laser beam, and a state in which the printed label is punched out. The laser light irradiation removes the laser light irradiated portion of the black layer 11 of the laminated base sheet 15 and shows the state where the white layer 12 can be seen at the printed portion 16. Further, the laser light output is increased and the black color is increased. The layer 11, the white layer 12, and the pressure-sensitive adhesive layer 13 are removed to form a punched portion 17, and the state where the printed label is punched on the release sheet 14 is shown.
In the present invention, a carbon dioxide laser oscillation device is preferably used as the laser oscillation device.

The tamper-proof label of the present invention uses, as a base material, a black layer on which information can be recorded by laser light irradiation, and a white layer below it, and preferably a brittle laminated sheet. Therefore, when the laminated sheet is brittle, it can be easily damaged when peeled off after being attached to an adherend, and is effective as a tamper-proof label. Furthermore, by including titanium dioxide particles together with fluorescent dyes in the pressure-sensitive adhesive layer provided on the white layer side, the label affixed to the adherend is removed neatly without damaging the laminated substrate sheet, for example. However, even after wiping off, the fluorescence remains on the trace of the adherend, and even if this fluorescence is not visible to the naked eye, it can be clearly seen by irradiating with ultraviolet rays. It is extremely useful for preventing tampering.
The tamper-proof label of the present invention can be used, for example, as an anti-theft label for automobiles, and the display contents such as features of automobile parts, electrical / electronic parts, precision machine parts, and precautions for handling. It is also useful for preventing tampering.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
In addition, the various characteristics about the tamper-proof label obtained in each example were determined by the following methods.
(1) Presence / absence of fluorescence A tamper-proof label from which a release sheet has been peeled off is attached to a melamine-coated board [manufactured by Partec Co., Ltd., “SPCC-SD”] via an adhesive layer. Was peeled off, and the presence or absence of fluorescence of the melamine-coated plate was confirmed by irradiating with ultraviolet rays in a standard light source device [manufactured by Macbeth, “Spectra Light II”].
Further, the melamine-coated plate with the label peeled off was wiped off using a non-woven fabric [Asahi Kasei Fibers Co., Ltd., “Bencot S-2”] soaked with toluene. The presence or absence was confirmed.
(2) Fluorescence intensity The tamper-proof label from which the release sheet has been peeled off is attached to a melamine coated plate [manufactured by Partec Co., Ltd., “SPCC-SD”] via an adhesive layer, and after 5 days at room temperature, the label is attached. It peeled off and the fluorescence intensity (excitation wavelength 354nm, fluorescence wavelength 439nm) of the melamine coating board was measured using the spectrofluorimeter [The JASCO Corporation make, "FP-6600"].
Further, the melamine-coated plate from which the label was peeled was wiped off using a non-woven fabric [manufactured by Asahi Kasei Fibers Co., Ltd., "Bencot S-2"] soaked with toluene, and the fluorescence intensity was measured in the same manner.

Production Example 1 Production of Laminated Base Sheet (1) Preparation of Resin Composition Z As resin composition Z, methyl methacrylate / methyl acrylate copolymer [manufactured by Mitsubishi Rayon Co., Ltd., “Acrypet MD”, elongation at break 2.6%] 60 parts by mass, methyl methacrylate / styrene / butyl acrylate copolymer [Mitsubishi Rayon Co., Ltd., “Acrypet RF065”, elongation at break 165.0%] 40 parts by mass, carbon black [Mitsubishi Made by Chemical Co., Ltd., trade name “RCF # 44”, average particle size 24 nm] 10 parts by mass, 176 parts by mass of dimethylformamide and 68 parts by mass of methyl ethyl ketone were mixed, sufficiently dispersed and dissolved, and solid content concentration 31 masses % Dispersion was prepared.
(2) Preparation of resin composition W As resin composition W, methyl methacrylate / methyl acrylate copolymer [manufactured by Mitsubishi Rayon Co., Ltd., “Acrypet MD”, elongation at break 2.6%], 60 parts by mass, Methyl methacrylate / styrene / butyl acrylate copolymer [Mitsubishi Rayon Co., Ltd., “Acrypet RF065”, elongation at break 165.0%] 40 parts by mass, rutile titanium dioxide [Ishihara Sangyo Co., Ltd., product The name “Typek CR-57” with an average particle size of 0.25 μm] is mixed with 30 parts by mass, 176 parts by mass of dimethylformamide, and 68 parts by mass of methyl ethyl ketone, sufficiently stirred and dispersed, and dissolved, with a solid content of 35 masses. % Dispersion was prepared.
(3) Production of Laminated Base Sheet The dispersion obtained in (1) above was applied to a peelable process sheet [Lintec Co., Ltd., trade name “Enplus-03”] and heated to 150 ° C. And heated and dried to form a black layer having a thickness of 20 μm. Next, the dispersion obtained in (2) above is applied onto the black layer, heated and dried at 150 ° C. to form a white layer having a thickness of 60 μm, and then the process sheet is peeled off, A laminated substrate sheet having a thickness of 80 μm composed of a black layer and a white layer was produced.

Example 1
Using a reactor equipped with a thermometer, a stirrer, a reflux condenser, and a nitrogen gas inlet tube, 90 parts by mass of a butyl acrylate monomer and 10 parts by mass of an acrylic acid monomer were charged, and 0.3 part by mass of azobisisobutyronitrile was added. In addition, an acrylic copolymer solution having a weight average molecular weight of 500,000 was obtained by polymerization at 80 ° C. for 8 hours in a nitrogen gas atmosphere.
4 parts by mass of an isocyanate cross-linking agent [Toyo Ink Mfg. Co., Ltd., “BHS8515”] with a solid content of 100 parts by mass of this copolymer solution, which is an oxazole fluorescent dye 2.5- 0.75 parts by mass of bis (5-tert-butyl-2-benzoxazolyl) thiophene in solid content, titanium dioxide [manufactured by Ishihara Sangyo Co., Ltd., “Taipeku CR-57”, average particle size of 0.25 μm] Was added in an amount of 12.7 parts by mass and further diluted with toluene to prepare an adhesive solution.
The pressure-sensitive adhesive solution is applied to the release surface of a release sheet [Lintec Co., Ltd., “SP-8E”] using a knife coater and dried at 80 ° C. for 1 minute. A layer was formed.
Next, the pressure-sensitive adhesive layer with a release sheet is bonded to the white layer side of the laminated base sheet composed of the white layer having a thickness of 60 μm and the black layer having a thickness of 20 μm obtained in Production Example 1, and a laser marker label A tamper-proof label comprising: Various characteristics of this label were evaluated. The results are shown in Table 1. The chemical structure of the fluorescent dye used is shown in the following formula (1).

Examples 2 and 3 and Comparative Examples 1 and 2
Various tamper-proof labels comprising laser marker labels were prepared in the same manner as in Example 1 except that the amounts of the fluorescent dye and titanium dioxide particles used in the preparation of the adhesive solution were as shown in Table 1. Various characteristics were evaluated for each label. The results are shown in Table 1.

  As is apparent from Table 1, it can be seen from the comparison between the example and the comparative example that the fluorescent layer remains even after wiping by including the titanium dioxide particles together with the fluorescent dye in the adhesive layer.

  The tamper-proof label of the present invention is preferably a laser marker label having a brittle substrate sheet, and the label is affixed to an adherend by containing a fluorescent dye and titanium dioxide particles in an adhesive layer. Later, when peeling, if the base sheet is brittle, it is easy to break, but even if it is peeled off without being damaged, the fluorescence remains on the peeled off surface of the adherend, even after wiping off The remaining fluorescence is extremely useful for preventing tampering.

DESCRIPTION OF SYMBOLS 1,11 Black layer 2,12 White layer 3,13 Adhesive layer 4,14 Release sheet 5,15 Laminated base sheet 10 Tamper-proof label 16 Print part 17 Punching part

Claims (6)

  A laser marker label having an adhesive layer on the white layer side of a laminated base sheet having a black layer capable of recording information by laser light irradiation and a white layer under the black layer, wherein the adhesive layer is A tamper-proof label comprising titanium dioxide particles together with a fluorescent dye.   The tamper-proof label according to claim 1, wherein the titanium dioxide particles are rutile type having an average particle size of 0.05 to 10 µm.   The tamper-proof according to claim 1 or 2, wherein the laminated base sheet is a brittle sheet containing at least one resin selected from an acrylic resin, an acrylic urethane resin and a urethane resin as a matrix resin. For labels.   The tamper-proof label according to any one of claims 1 to 3, wherein the thickness of the black layer in the laminated base sheet is 5 to 30 µm and the thickness of the white layer is 50 to 200 µm.   The tamper-proof label according to any one of claims 1 to 4, wherein the pressure-sensitive adhesive layer is a cross-linked acrylic pressure-sensitive adhesive layer.   The tamper-proof label according to any one of claims 1 to 5, wherein the laser beam for recording information on the black layer is generated by a carbon dioxide laser oscillator.

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