JP2015114583A - Heat-shrinkable cylindrical label - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-shrinkable cylindrical label that can be rapidly heat-shrunk by using a near-infrared ray, and can prevent distortion of the heat shrinkage.SOLUTION: A heat-shrinkable cylindrical label includes: a label base material 2 that has a heat-shrinkable film 3x having heat-shrinkability, and a transparent heating layer 4x containing a near-infrared ray exothermic compound which absorbs a near-infrared ray to generate heat, the label base material 2 formed into a cylindrical shape.

Description

  The present invention relates to a heat-shrinkable cylindrical label attached to a beverage container or the like.

The heat-shrinkable cylindrical label is one of packaging materials that can be attached to a beverage container or the like by heat shrinkage, and is also referred to as a shrink film or a cylindrical shrink. Heat-shrinkable cylindrical labels can be broadly classified into the following two types according to the mounting method for adherends such as containers.
The first heat-shrinkable cylindrical label is formed in a cylindrical shape by overlaying and bonding the back surface of the second side end portion to the surface of the first side end portion of the label substrate having the heat-shrinkable film. A cylindrical body. The first heat-shrinkable cylindrical label is heat-sealed after being externally fitted to the adherend, and thereby heat-shrink and adheres to the adherend.

  The second heat-shrinkable cylindrical label is bonded to the adherend on the back side of the first side end of the label base material having the heat-shrinkable film, and the label base material is wound around the adherend, It is the cylindrical body formed in the cylinder shape by adhere | attaching the back surface of the 2nd side edge part of a label base material on the surface of a 1st side edge part. The second heat-shrinkable cylindrical label is in a state of being externally fitted to the adherend as soon as it is formed into a cylindrical shape. To do.

When heat-shrinkable cylindrical labels are thermally shrunk, generally steam or hot air is used as a heat source, but heat-shrinkable cylindrical labels using infrared rays as a heat source are also known (Patent Document 1). .
Specifically, Patent Document 1 discloses a heat-shrinkable cylindrical label in which a shrink film is provided with a black ink layer containing carbon black as a substance that generates heat by absorbing infrared rays.
In such a heat-shrinkable cylindrical label of Patent Document 1, the portion where the black ink layer is laminated is greatly shrunk by irradiating with infrared rays. Must be provided throughout.

However, when the black ink layer is provided on the entire surface, black or black approximate color cannot be used as a color for expressing the design, and there is a problem that the design applied to the heat-shrinkable cylindrical label is limited.
In addition, when a black ink layer that absorbs infrared rays and generates heat is partially provided, black ink and other color inks (color inks that can be visually distinguished from black) are not formed on the black ink layer. ) When printing a design, the film portion corresponding to the black design is thermally contracted, while the film portions corresponding to other color designs are not thermally contracted, which causes the entire design to be distorted. .

  In Patent Document 2, a transparent printed label having a transparent near-infrared absorbing layer containing a near-infrared absorber on the outer surface of the film is used, and the defects of the label are inspected using the near-infrared absorbing layer. However, in this document, there is no disclosure or suggestion of using a heat generating material as the near-infrared absorbing layer and shrinking the label using it as a heat source.

JP 2009-161191 A JP 2003-302905 A

  An object of the present invention is to provide a heat-shrinkable cylindrical label which can be rapidly heat-shrinked using near infrared rays and which can prevent heat-shrinkage distortion.

  The heat-shrinkable cylindrical label of the present invention has a label substrate having a heat-shrinkable film having heat-shrinkability and a transparent heat-generating layer containing a near-infrared heat-generating compound that generates heat by absorbing near-infrared light. The label base material is formed into a cylindrical shape.

In a preferred heat-shrinkable cylindrical label of the present invention, the near-infrared exothermic compound contains a diimonium salt compound.
In a further preferred heat-shrinkable cylindrical label of the present invention, the heat generating layer is disposed on the cylindrical outermost layer.

  In a further preferred heat-shrinkable cylindrical label of the present invention, the label base material further has a printing layer, and the printing layer is disposed inside the cylinder more than the heat generating layer.

The heat-shrinkable cylindrical label of the present invention can be rapidly heat-shrinked using near infrared rays.
Furthermore, the heat-shrinkable cylindrical label of the present invention is less likely to be distorted during heat shrinkage, and therefore the design is not distorted and the shrinkage finish is beautiful.

The perspective view of the 1st heat-shrinkable cylindrical label of this invention. The front view of the 2nd heat-shrinkable cylindrical label of this invention. The front view which shows the preparation middle of the 2nd heat-shrinkable cylindrical label. The top view of one label base material of a 1st embodiment. The expanded sectional view cut | disconnected by the VV line | wire of FIG. The expanded sectional view of the other label base material of a 1st embodiment. The expanded sectional view of one label base material of a 2nd embodiment. The expanded sectional view of the other label base material of 2nd Embodiment. The expanded sectional view of the other label base material of 2nd Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In this specification, the surface of a label base material refers to the surface which becomes the outer side of the cylindrical shape when it is formed into a cylindrical shape (that is, when a heat-shrinkable cylindrical label is formed). The back surface of this indicates the surface that becomes the inside of the cylindrical shape. Furthermore, the description “PPP to QQQ” means “PPP or more and QQQ or less”.
In each figure, it should be noted that the thickness and dimensions are different from the actual ones.

[Outline of heat-shrinkable cylindrical label]
The heat-shrinkable cylindrical label of the present invention has a label base material having a heat-shrinkable film having heat-shrinkability and a heat generating layer that generates heat by near infrared rays, and the label base material is formed into a cylindrical shape. It consists of a body.
The heat-shrinkable cylindrical label of the present invention may be one that has been formed in a cylindrical shape before being externally fitted to the adherend (first heat-shrinkable cylindrical label), or may be attached to the adherend. It may be formed into a cylindrical shape at the same time as the fitting (second heat-shrinkable cylindrical label).

  For example, as shown in FIG. 1, the first heat-shrinkable cylindrical label 1A of the present invention is rounded with the back side of the label substrate 2 inside, and one direction thereof (the main heat-shrink direction) is the circumferential direction. In this way, the label base material 2 is formed in a cylindrical shape by overlapping and bonding the back surface of the second side end portion 22 to the surface of the first side end portion 21.

Moreover, as shown in FIG. 2, the 2nd heat-shrinkable cylindrical label 1B of this invention adhere | attaches the back surface of the 1st side edge part 21 of the label base material 2 on the to-be-adhered body 10, and is the one direction. After the label substrate 2 is wound around the adherend 10 so that the (main heat shrink direction) is the circumferential direction, the back surface of the second side end portion 22 is overlapped on the surface of the first side end portion 21. It is formed in a cylindrical shape by bonding together.
FIG. 3 shows a process of forming the second heat-shrinkable cylindrical label 1B, the back surface of the first side end 21 of the label base material 2 is adhered to the adherend 10, and the label base material 2 is attached to the adherend. 10 shows a state before being wound around.
The first side end portion 21 is one of both side portions extending in the other direction on one side of the label base material 2, and the second side end portion 22 is the other side of the both side portions. .
This will be specifically described below.

[First Embodiment]
(Label substrate)
In the label base material of the first embodiment, the heat generating layer is disposed on the outermost layer (when the label base material is formed in a cylindrical shape, the heat generating layer is the outermost layer).
In addition, the label base material of each embodiment including 1st Embodiment is applicable to any of the said 1st and 2nd heat-shrinkable cylindrical labels 1A and 1B.

Specifically, the label base material 2 constituting the heat-shrinkable cylindrical label is formed in a substantially rectangular shape or a substantially square shape in plan view as shown in FIG.
As shown in FIG. 5, the label substrate 2 includes a heat-shrinkable film 3 x having heat-shrinkability, a transparent heat-generating layer 4 x that generates heat by near infrared rays, and a printed layer formed by applying a required ink. 5x.
The stacking order of these layers can be designed as appropriate, but in this embodiment, from the front surface side toward the back surface side (when the label substrate 2 is formed in a cylindrical shape, from the outer surface side toward the inner surface side. ), The heat generating layer 4x, the heat-shrinkable film 3x, and the printing layer 5x are laminated and adhered in this order.

  Therefore, the heat generating layer 4x is disposed on the outermost side of the heat-shrinkable cylindrical label, and the printing layer 5x is disposed on the innermost side of the heat-shrinkable cylindrical label. In addition, you may provide a well-known overcoat layer (protective layer) suitably in the surface of the heat generating layer 4x, and / or the back surface of the printing layer 5x (not shown). Such an overcoat layer can be formed by, for example, a colorless and transparent medium ink or varnish. The overcoat layer conceptually forms part of a layer in which it is provided (for example, a heat generation layer, a printing layer, or the like).

Moreover, in this embodiment, it is not restricted to the layer structure shown in FIG. 5 on condition that the heat generating layer 4x is located in a cylindrical outermost layer. For example, as shown in FIG. 6, the printing layer 5x may be provided between the heat generating layer 4x and the heat-shrinkable film 3x. In addition, although not shown, it has two printing layers, one printing layer is provided between the heat generating layer and the heat shrinkable film, and another printing layer different from this is formed on the back surface of the heat shrinkable film. It may be provided. By disposing the print layer 5x on the inner side of the heat generating layer 4x, even when the print layer 5x is configured to include black ink, it is possible to effectively prevent distortion of the film during heat shrinkage. Specifically, black absorbs near infrared rays and easily generates heat. However, the heat generating layer absorbs near infrared rays and generates heat when the heat generating layer is disposed outside the print layer including black. When the heat generating layer absorbs near infrared rays, the amount of near infrared rays reaching the print layer is extremely reduced. As a result, the printed layer in which the design such as letters and patterns is represented with black ink is less likely to generate heat due to near infrared rays, and the heat-shrinkable film in the black-corresponding portion of the printed layer is partially heat-shrinked. Can be prevented.
In addition, the said label base material 2 may further be provided with arbitrary functional layers other than a printing layer and a heat-shrinkable film (not shown). Examples of the functional layer include a gas barrier layer and a heat-sensitive adhesive layer.

The heat generating layer 4x may be provided on a part of the heat-shrinkable film 3x. However, since heat is applied to the entire heat-shrinkable film substantially uniformly through the heat-generating layer 4x, the heat-generating layer 4x is The heat-shrinkable film 3x is preferably provided on the entire surface.
A desired design may be represented on the printing layer 5x using a desired color ink, and the printing layer 5x may be composed of a single color ink without a pattern (so-called solid printing). layer).
Also about the printing layer 5x, it may be provided in the whole heat-shrinkable film 3x, and may be provided in a part. For example, the printed layer 5x representing the design is provided on substantially the entire heat-shrinkable film except for the back surface of the second side end (adhered to the surface of the first side end).

(Heat shrinkable film)
The heat-shrinkable film 3x having heat-shrinkability is a film having a property of heat-shrinking when heated to a required temperature (for example, 70 ° C to 120 ° C).
The heat-shrinkable film 3x is a film having heat-shrinkability in at least one direction (one direction becomes the circumferential direction when formed in a cylindrical shape).
As the heat-shrinkable film 3x, a film that thermally contracts or stretches in the other direction (the other direction is a direction orthogonal to the one direction in the film plane) may be used.
The heat shrinkage rate of the heat-shrinkable film 3x is not particularly limited. The heat shrinkage rate in one direction when the heat-shrinkable film 3x is heated to 90 ° C. is, for example, 30% or more, preferably 40% or more, more preferably 50% or more.
In addition, when the heat-shrinkable film 3x slightly heat-shrinks or stretches in the other direction, the heat shrinkage rate in the other direction when heated to 90 ° C. is, for example, −10% to 15%, preferably -3% to 10%. The minus of the heat shrinkage rate in the other direction means thermal expansion.

The heat shrinkage rate when heated to 90 ° C. is the length of the film before heating (original length) and the length of the film after being immersed in warm water of 90 ° C. for 10 seconds (after immersion). Length) and is obtained by substituting into the following equation.
Formula: heat shrinkage rate (%) = [{(original length in one direction (or other direction)) − (length after immersion in one direction (or other direction))} / (one direction (or other direction) ) Original length)] × 100.

The heat-shrinkable film 3x in the present embodiment may be transparent (one having high visible light transmittance) or opaque, but may be transparent in order to make the printing layer 5 visible from the outside. preferable. Transparent includes colored transparent or colorless and transparent, but is preferably colorless and transparent. Examples of the opaque heat-shrinkable film 3 include a milky white film. In addition, when using the opaque heat-shrinkable film 3, a printing layer is provided in the surface side of a film.
The degree of transparency of the heat-shrinkable film 3x can be set as appropriate.
The total light transmittance (visible light transmittance) of the heat-shrinkable film 3x is, for example, 70% or more, preferably 80% or more, and more preferably 85% or more.
The total light transmittance refers to a value measured by a measuring method based on JIS K7105 (plastic optical property testing method).

The heat-shrinkable film 3x may have a high near-infrared transmittance, or may have a low near-infrared transmittance (a film that absorbs or reflects near-infrared light). For example, the heat-shrinkable film 3x may be a film having a near infrared transmittance of 50% or more, or may be a film having a near infrared transmittance of 50% or less.
In the present embodiment, since the heat generating layer 4x is disposed in the outermost layer, when the heat-shrinkable cylindrical label is irradiated with near infrared rays, there is no intervening layer, and the near infrared rays directly hit the heat generating layer 4x. Because. That is, when an arbitrary layer such as a heat-shrinkable film or a printing layer is present outside the heat generating layer 4x, when the layer is irradiated with near infrared rays, the layer absorbs the near infrared rays, thereby causing the proximity to the heat generating layer. The amount of incident infrared rays becomes small, or the layer may generate heat due to near infrared rays, and the heat shrinkable film may be distorted due to unexpected shrinkage. In this respect, in the present embodiment, the heat generating layer 4x is disposed in the cylindrical outermost layer, so that the heat generating layer 4x absorbs near infrared rays and the heat shrinkable film is quickly and beautifully contracted by the heat. Can do.

The heat-shrinkable film 3x may be a single layer film or a laminated film in which a plurality of layers are laminated and integrated.
When the heat-shrinkable film 3x is a laminated film having a plurality of layers, the heat-shrinkable film 3x as a whole has heat-shrinkability in the plurality of layers on the condition that the heat-shrinkable film 3x has the heat-shrinkability. No layers may be included.
The thickness of the heat-shrinkable film 3x is not particularly limited, but is generally 10 μm to 100 μm, preferably 20 μm to 60 μm.

  The material for forming the heat-shrinkable film 3x is not particularly limited, and a conventionally known thermoplastic resin can be used. As the forming material, for example, one kind selected from polyester resins such as polyethylene terephthalate and polylactic acid, olefin resins such as polypropylene, polystyrene resins such as polystyrene, cyclic olefin resins, and thermoplastic resins such as vinyl chloride resin is mainly used. What has a component, or what has 2 or more types of mixtures as a main component is mentioned. When the heat-shrinkable film 3x is a laminated film having a plurality of layers, each of these layers may be formed of the same kind of resin or different resins.

The heat-shrinkable film 3x can be obtained by forming the forming material and further stretching it in at least one direction (main heat-shrink direction). If necessary, after forming the forming material, the film may be stretched in one direction and the other direction.
Stretching can be performed by a known method such as a tenter method or a tubular method. The stretching treatment is usually performed at a temperature of 70 ° C. to 110 ° C. and stretched in one direction by 2.0 to 8.0 times, preferably about 3.0 to 7.0 times. Furthermore, if necessary, the stretching process may be performed in other directions at a low magnification of, for example, 1.5 times or less. The obtained film becomes a uniaxially stretched film that can be thermally contracted in one direction or a biaxially stretched film that can be thermally contracted in the other direction.

(Heat generation layer)
The transparent heat generating layer 4x contains a near-infrared heat-generating compound that generates heat by near-infrared light. When this compound generates heat, heat is generated around it (other components constituting the heat-generating layer 4x and the heat-shrinkable film 3x). Propagating, and the heat-shrinkable film 3x shrinks.
The near-infrared transmittance of the heat generating layer 4x is, for example, 50% or less, preferably 40% or less, and more preferably 30% or less. Such a heat generating layer 4x can sufficiently absorb near infrared rays and generate a large amount of heat.

The transparent heat-generating layer 4x is composed of a near-infrared heat-generating compound that generates heat by near-infrared light, a matrix resin that fixes the compound, and various additives that are contained as necessary.
The near-infrared exothermic compound is not particularly limited as long as it absorbs near-infrared rays and generates heat, and examples thereof include a diimonium salt compound.
As specific examples of the diimonium salt compound, for example, those disclosed in JP 2010-249964 can be used.
As the diimonium salt compounds that can be used in the present invention, those disclosed in JP-A 2010-249964, [0024] to [0050] are described in this specification, and the description thereof is omitted.

The heat generating layer 4x can be formed by applying a composition containing a near-infrared heat generating compound, a matrix resin and an additive to a heat-shrinkable film and solidifying it.
The thickness of the heat generating layer 4x is not particularly limited, but is, for example, 0.1 μm to 5 μm, and preferably 0.5 μm to 5 μm.
The matrix resin is not particularly limited, and examples thereof include resin components used in known printing inks, such as acrylic resins, urethane resins, cellulose resins, polyamide resins, and vinyl acetate resins.
The composition may be a solvent type dissolved in a solvent or an emulsion type dispersed in an aqueous solvent.
Further, as the matrix resin, an active energy ray curable resin such as an ultraviolet curable resin may be used. As specific examples of the active energy ray-curable resin and a method for forming a layer containing a near-infrared heat-generating compound using the resin, those disclosed in JP-A-2010-249964, [0051] to [0060] are described in this specification. The description is omitted as described in.

(Print layer)
As described above, the printing layer 5x is a layer formed by printing a known ink by a known printing method. The printing layer 5x can be formed by one printing or multiple printings.
When the design is displayed on the printing layer 5x, the design is not particularly limited, and examples thereof include an image, an explanatory note, a component display, and an optical reading symbol such as a barcode or a two-dimensional code.
Although the thickness of the printing layer 5x is not specifically limited, For example, they are 0.1 micrometer-10 micrometers.

As described above, in the present embodiment in which the heat generating layer 4x is disposed in the outermost layer, the heat generating layer 4x absorbs near infrared rays, and the heat shrinkable film can be quickly and beautifully contracted by the heat. .
For this reason, the printing layer 5x may be transparent (having a high visible light transmittance) or opaque. Further, the printing layer 5x may transmit near infrared rays, or may absorb or reflect near infrared rays.
Therefore, the color of the ink of the printing layer 5x is not particularly limited, and any color such as black, silver, white, red, blue, and yellow can be used.

The heat-shrinkable cylindrical labels 1A and 1B of the present invention rapidly heat-shrink by irradiating near infrared rays from the outside of the cylindrical shape. This is because the heat generating layer 4x containing the near infrared heat generating compound absorbs near infrared light and generates heat, and the heat propagates to the heat shrinkable film 3x.
The wavelength of the near infrared ray to be irradiated is in the range of 780 nm to 2000 nm, preferably 900 nm to 1400 nm.
According to the heat-shrinkable cylindrical labels 1A and 1B of the present invention, the heat-shrinkable film 3x can reach the shrinkage limit within 3 seconds after the near-infrared irradiation. is there.

[Second Embodiment]
As for the label base material of 2nd Embodiment, arbitrary layers are arrange | positioned on the outer side of the heat-generating layer.
Hereinafter, although the label base material of 2nd Embodiment is demonstrated, description is abbreviate | omitted about the structure and effect similar to 1st Embodiment (as what was demonstrated).

  As shown in FIG. 7, the label substrate 2 of the present embodiment is directed from the front surface side toward the back surface side (when the label substrate 2 is formed in a cylindrical shape, from the outer surface side toward the inner surface side). The heat-shrinkable film 3y, the printing layer 5y, and the heat generating layer 4y are laminated and adhered in this order.

The present embodiment is not limited to the layer configuration shown in FIG. 7 on the condition that the heat generating layer 4y is not located in the cylindrical outermost layer.
For example, as shown in FIG. 8, the label base material 2 may be laminated and adhered in the order of the heat-shrinkable film 3y, the heat generating layer 4y, and the printing layer 5y from the front surface side to the back surface side. The configuration example of FIG. 8 is also an example in which the print layer 5y is disposed on the inner side of the heat generating layer 4y.
Moreover, as shown in FIG. 9, the label base material 2 may be laminated and bonded in the order of the printed layer 5y, the heat-shrinkable film 3y, and the heat generating layer 4y from the front surface side to the back surface side.
In addition, although not shown, in addition to the layer structure shown in FIGS. 7 to 9, another printed layer may be provided on the back surface of the heat generating layer, or any other than the printed layer and the heat shrinkable film The functional layer may be further provided.

In the present embodiment, the near-infrared transmittance of all the layers existing outside the heat generating layer 4y is preferably 50% or more, more preferably 70% or more, and particularly preferably 85% or more. However, all the layers existing outside the heat generating layer 4y are all layers corresponding to the heat generating layer 4y and overlapped on the outside thereof, and the heat generating layer is not provided in a part of the heat-shrinkable film 3y. If there is, all the layers corresponding to the region may have a near infrared transmittance of 50% or more as described above, or less than 50%.
For example, in the layer configuration shown in FIG. 7 and FIG. 9, both the heat-shrinkable film 3y and the printing layer 5y have a near infrared transmittance of preferably 50% or more, more preferably 70% or more, and particularly preferably. Is 85% or more.
In the layer structure shown in FIG. 8, the near-infrared transmittance of the heat-shrinkable film 3y is preferably 50% or more, more preferably 70% or more, and particularly preferably 85% or more.
Further, in other layer configurations not shown, the near-infrared transmittance of all the layers existing outside the heat generating layer 4y is preferably 50% or more, more preferably 70% or more, and particularly preferably 85% or more. It is.

  Near-infrared rays were irradiated from the outside of the heat-shrinkable cylindrical label when the near-infrared transmittance of all the layers existing outside the exothermic layer 4y or one or more of the layers existing outside was less than 50%. Sometimes, all the layers or one or more layers existing outside absorb near infrared rays, so that the heat generating layer 4y hardly generates heat, or all the layers existing outside or one or more layers generate heat. This is because the heat-shrinkable film may be distorted due to unexpected shrinkage.

Specifically, the heat generating layer 4y is the same as in the first embodiment.
The heat-shrinkable film 3y in this embodiment has a high near infrared transmittance.
The near-infrared transmittance of the heat-shrinkable film 3y is, for example, 50% or more, preferably 70% or more, and more preferably 85% or more.
Here, in the present specification, the near-infrared transmittance is a value obtained by measuring the spectral transmittance with respect to light having a wavelength of 780 nm to 2000 nm and calculating in the same manner as the total light transmittance.

The heat-shrinkable film 3y is preferably a transparent film as in the first embodiment.
The colorless and transparent heat-shrinkable film formed from the thermoplastic resin shown in the first embodiment is usually preferably near 50% or more (more preferably 70% or more, particularly preferably 85% or more). Infrared transmittance.

The near-infrared transmittance of the printing layer 5y in the present embodiment is, for example, 50% or more, preferably 70% or more, and more preferably 85% or more.
However, when the print layer 5y is disposed inside the heat generating layer 4y as in the layer configuration shown in FIG. 8, the print layer 5y has a near infrared transmittance as in the first embodiment. There is no preferred range for and any color such as black, silver, white, red, blue can be used.

The printing layer 5y having a near infrared transmittance of 50% or more can be formed by using an ink other than black and silver inks (for example, white, red, blue, yellow, green, etc.).
The printing layer 5y having a near-infrared transmittance of 50% or more may use a known printing ink (for example, an ink exhibiting white, red, blue, yellow, green, etc.) other than a known black and silver color ink. .

  According to the study by the inventors, when a printing layer is formed using black and silver inks, the near-infrared transmittance of the printing layer is less than 50%, and such a printing layer is If it is arranged outside the heat generating layer, the heat shrinkable film is distorted and heat shrinks.

  EXAMPLES Hereinafter, an Example is shown and this invention is explained in full detail. However, the present invention is not limited to the following examples.

[Materials used]
Heat-shrinkable film: a film that thermally shrinks in a uniaxial direction mainly composed of polyethylene terephthalate (trade name “LX-10S” manufactured by Mitsubishi Plastics, Inc., thickness 40 μm, total light transmittance 90%).
Heat-generating layer forming material: acrylic medium ink (trade name “STR heat-resistant CS medium” manufactured by Dainichi Seika Kogyo Co., Ltd.) and diimonium salt compound (trade name “CIR-FS163M” manufactured by Nippon Carlit Co., Ltd.) λMax = 1090 1% by mass of ± 7 nm).

[Example 1]
A white ink (trade name “M-conc white for fine wrap NTV PET” manufactured by DIC Corporation) was printed on the entire back surface of the heat-shrinkable film to form a white print layer having a thickness of about 1 μm.
On the other hand, a solvent (ethyl acetate: isopropyl alcohol (weight ratio) = 1: 1) was added to the material for forming the heat generating layer to adjust the viscosity so that gravure printing was possible.
This forming material was applied to the entire surface of the heat-shrinkable film provided with a white printing layer on the back surface by a single coating using a gravure printing cylinder (70 lines, 0 degree). After application, the film was naturally dried to form a heat generation layer having a thickness of about 1 μm on the surface of the heat-shrinkable film. In this way, a label substrate having a layer structure shown in FIG. 5 was produced.

[Example 2]
A silver ink (trade name “NT Hiramic High Brightness Silver” manufactured by Dainichi Seika Kogyo Co., Ltd.) was printed on the entire back surface of the heat shrinkable film to form a silver print layer having a thickness of about 1 μm. Further, white ink (trade name “High Conc White for Fine Wrap NTV PET” manufactured by DIC Corporation) was printed on the entire back surface of the silver print layer to form a white print layer having a thickness of about 1 μm.
In the same manner as in Example 1, a heat generating layer having a thickness of about 1 μm is formed on the entire surface of the film in which the silver print layer / white print layer / heat-shrinkable film is laminated in order from the back side. Was made.

[Heat shrinkage test]
A sample piece was prepared by cutting the label base material of Example 1 into a strip shape having a length in the TD direction (a direction in which heat shrinks): 170 mm and a length in the MD direction: 15 mm.
An infrared lamp (trade name “ZKC3000 / 500G” manufactured by Heraeus Co., Ltd., maximum wavelength 1300 nm, rated output 3000 W) is placed on the surface side of the sample piece (the side on which the heat generation layer is formed). It arrange | positioned so that the distance with the output surface of may become 90 mm.
And with the said infrared lamp, near infrared rays were applied to the surface of the sample piece, the TD direction length of the film was measured for every predetermined time, and the thermal contraction rate was calculated | required according to the following formula. The light emitted from the infrared lamp is roughly 3% visible light, 58.2% near-infrared light, 28.2% mid-infrared light (wavelength greater than 2000 nm and less than 3500 nm), and 10.6%. It consists of far-infrared rays (wavelength over 3500 nm and 5000 nm or less).
Thermal contraction rate (%) = {(length in TD direction before light irradiation−length in TD direction after elapse of predetermined time) / length in TD direction before light irradiation} × 100.

As for the label base material of Example 2, as in the case of the label base material of Example 1 (except for the following points), near infrared rays were applied to confirm the change in the heat shrinkage rate every predetermined time. However, in the label base material of Example 2, it arrange | positioned so that the distance of the surface of a sample piece and the output surface of an infrared lamp might be set to 140 mm.
The results of Examples 1 and 2 are shown in Table 1.

[Evaluation]
The label base materials of Examples 1 and 2 could be rapidly heat-shrinked using near infrared rays.

  1A, 1B ... heat-shrinkable cylindrical label, 2 ... label base material, 3x, 3y ... heat-shrinkable film, 4x, 4y ... heating layer, 5x, 5y ... printing layer

Claims (4)

  A heat-shrinkable film in which a label base material having a heat-shrinkable film having heat-shrinkability and a transparent heat-generating layer containing a near-infrared heat-generating compound that generates heat by absorbing near-infrared rays is formed in a cylindrical shape. Cylindrical label.   The heat-shrinkable cylindrical label according to claim 1, wherein the near-infrared exothermic compound contains a diimonium salt compound.   The heat-shrinkable cylindrical label according to claim 1 or 2, wherein the heat generating layer is disposed on the cylindrical outermost layer. The label substrate further has a printing layer,
The heat-shrinkable cylindrical label according to any one of claims 1 to 3, wherein the printed layer is disposed inside the cylindrical shape with respect to the heat generating layer.

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