JP4819541B2 - Shrink label - Google Patents

Description

  The present invention relates to a shrink label used as a product label or a sealing cap seal by attaching to a container by being thermally contracted by being covered with various containers such as bottles, cans, and PET bottles (polyethylene terephthalate bottles). .

  2. Description of the Related Art Conventionally, as a shrink label that is attached to various containers by heat shrinking, a label having a heat shrinkability, for example, a PET base material and a printed layer provided on the base material is known. This type of shrink label is tubular and heated by covering the container, so that the base material shrinks and the printed layer shrinks following the base material, so that the entire label shrinks and is attached to the container. .

  By the way, the above-described shrink label is used for decoration for advertising and product display by the design of the printed layer, etc., but in order to increase the willingness to purchase etc., it has been demanded to improve its decoration effect. .

  Then, this invention is made | formed in view of the said request, and makes it a subject to provide the shrink label which can improve a decoration effect further than the decoration effect only by the design etc. of a printing layer.

The present invention has been made to solve the above problems, and the shrink label according to the present invention includes a base material having heat shrinkability and a printed layer provided on the base material, and at least a part of the printed layer is , it looks containing a base resin and an inorganic pigment having a high glass transition temperature than the glass transition point of the substrate, with the substrate is transparent, the print layer on the back surface of the substrate facing inward upon mounting of the container The formed base material in the region corresponding to the printed layer has a concavo-convex shape in the surface direction due to heat shrinkage .

  When the shrink label having such a structure is heated to be attached to the container, the base material having heat shrinkability is first softened and tends to shrink. At this time, at least a part of the printing layer includes the base resin having a glass transition point higher than the glass transition point of the substrate and the inorganic pigment, and therefore stretches against the shrinkage of the substrate. When the printed layer stretches against the shrinkage of the base material, the base material does not shrink uniformly and shrinks non-uniformly. As a result, the region corresponding to the printed layer of the base material after shrinkage has an uneven shape in the shrinking direction. Become. Thus, when the base material has an uneven shape, the appearance texture of the portion looks different compared to the case without the uneven shape, and the tactile sensation also differs compared to the case without the uneven shape. .

  Thus, in the shrink label according to the present invention, at least a part of the printed layer contains the base resin having a glass transition point higher than the glass transition point of the base material and the inorganic pigment, so A region corresponding to the printing layer has an uneven shape in the shrinking direction. Therefore, the texture of the appearance at the time of wearing looks different compared to the case where there is no uneven shape, and the tactile sensation is also different compared to the case where there is no uneven shape. Therefore, an effect that the decoration effect can be further improved than the decoration effect by only the design of the printed layer such as the conventional shrink label is exhibited.

Hereinafter, an embodiment of a shrink label according to the present invention will be described with reference to the drawings.
FIG. 1 shows a cap seal 2 using a shrink label 1 in the present embodiment. The shrink label 1 is not limited to being used as the cap seal 2 as in the present embodiment. For example, the shrink label 1 may be used as a label (tubular shrink label, wound shrink label) attached to the body of the container. Of course it is possible.

  The cap seal 2 is formed by making the sheet-like shrink label 1 into a cylindrical shape, and is attached to the mouth of the container in a close contact state by covering the mouth of the container (not shown) and thermally contracting. The upper end portion 21 of the cap seal 2 is bent inwardly (in the cylindrical shape in the radial direction), and presses the lid portion (not shown) of the container in the mounted state.

  The cap seal 2 is provided with a perforation 22 over the entire axial direction of the cylindrical shape. The perforations 22 are provided in two strips so as to be substantially parallel with a predetermined distance in the circumferential direction. Between the two perforations 22, 22, a knob 23 is provided that extends downward from the lower end edge 2 a of the cap seal 2 in a tongue-like shape. When the cap seal 2 attached to the container is peeled off, the knob 23 is picked up with fingers and raised up. Then, the cap seal 2 is broken along the two perforations 22 and 22, and the cap seal 2 can be peeled from the container.

  As shown in FIG. 2, the shrink label 1 constituting the cap seal 2 includes a base material 11 having heat shrinkability, a first print layer 12 provided on the base material 11, and a second print layer 13 provided on the base material 11. And. Specifically, the shrink label 1 includes a sheet-like base material 11 having heat shrinkability, a first printing layer 12 provided in a predetermined region of the back surface 11a of the base material 11, and a first printing of the back surface 11a of the base material 11. And a second printed layer 13 provided in a region where the layer 12 is not provided. Note that FIG. 2 is a schematic diagram, and the dimensions and ratios in the figure do not coincide with the actual ones.

  The base material 11 is a biodegradable resin film having heat shrinkability, and is preformed in a shape corresponding to the mouth portion of the container to which the cap seal 2 is attached. Specifically, the base material 11 is a substantially rectangular sheet, and after making it into a cylindrical shape so that the direction corresponding to the circumferential direction of the container becomes a long side, both ends of the base material 11 are bonded with a solvent or an adhesive. Then, the base material 11 is preliminarily molded by being contracted into a cylindrical mold having a diameter larger than the mouth portion of the container and having a diameter extending downward. The thickness of the substrate 11 can be appropriately selected in consideration of strength, handleability, economy, etc., but is generally 20 to 100 μm, preferably about 30 to 70 μm.

  The thermal contraction rate of the base material 11 is 30% or more (for example, 30 to 70%), particularly 50 to 70% in the main stretching direction (the circumferential direction of the container) when immersed in hot water at 90 ° C. for 10 seconds. Is preferred. When the heat shrinkage rate of the substrate 11 is less than 30%, it is difficult to tightly package the mouth of the container. In the direction perpendicular to the main stretching direction, it is preferably −3% to 15%, particularly preferably about −1% to 10%.

  Moreover, the base material 11 is resin which has biodegradable resin as a main component. Specifically, the base material 11 is a biodegradable resin containing polylactic acid (PLA) as a main component and a resin containing a polylactic acid polymer as a main component. The glass transition point of the substrate 11 is 50 ° C. to 60 ° C. In addition, the base material 11 is not restricted to the polylactic acid-type polymer which is biodegradable resin, For example, a polypropylene type (glass transition point-20 degreeC grade) may be sufficient. However, polylactic acid is preferable because it has not only a glass transition point of 50 ° C. to 60 ° C., but also a low shrinkage stress and a high shrinkage rate, and thus easily forms an uneven shape. The shrinkage stress is preferably 5 MPa or less when immersed in hot water at 85 ° C. for 10 seconds.

  Here, the glass transition point is a temperature at which glass transition occurs in a resin that is a polymer compound (generally expressed as TG). This is the temperature at which the amorphous portion of the polymer compound having a sparse and soft amorphous portion starts to move. Resin, which is a polymer compound, greatly changes its physical properties at the boundary of the glass transition point, and, for example, its elastic modulus rapidly decreases. The glass transition point in this embodiment is a glass transition point measured using DSC 6200 (Seiko Instruments Inc.) (temperature rising condition 5 ° C./min).

  The polylactic acid polymer is a polymer containing lactic acid (D-lactic acid, L-lactic acid, DL-lactic acid, or a mixture thereof) as a monomer component. The polylactic acid polymer may be a copolymer of lactic acid and other hydroxycarboxylic acid or lactone. In this case, examples of other hydroxycarboxylic acid include glycolic acid, 2-methyllactic acid, 2-hydroxylic acid. Examples include butyric acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 2-hydroxy-3-methylbutyric acid, 2-hydroxy-3,3-dimethylbutyric acid, and 2-hydroxycaproic acid. Examples of lactones include γ-butyrolactone, δ-valerolactone, and ε-caprolactone.

  The proportion of lactic acid in all monomers constituting the polylactic acid polymer is generally 50 mol% or more, preferably 80 mol% or more, more preferably 90 mol% or more, and particularly 95 mol% or more ( For example, 100 mol%) is preferable.

  In addition, you may use a polylactic acid-type polymer individually or in mixture of 2 or more types. Specifically, two or more polylactic acid polymers having different ratios of L-lactic acid and D-lactic acid can be used in combination. Moreover, the base material 11 should just contain the polylactic acid-type polymer as a main component, and may contain a small amount of resin components other than a polylactic acid-type polymer. For example, biodegradable resins such as aliphatic polyester, aliphatic aromatic polyester, aliphatic polyester amide, aliphatic polyester ether, and aliphatic polyester carbonate can be included.

  In this case, the proportion of the polylactic acid polymer in the entire resin of the substrate 11 is usually 50% by weight or more (50 to 100% by weight, particularly 50 to 95% by weight), preferably 60% by weight or more (60 to 100%). % By weight, particularly 60 to 90% by weight), more preferably 65% by weight or more (65 to 100% by weight, particularly 65 to 85% by weight). If the ratio of the polylactic acid polymer is small, the transparency may be lowered. In order to improve the shrinkability, it is preferable to include an aliphatic polyester (for example, about 10% to 40%). However, when a large amount of the aliphatic polyester is mixed, it becomes too soft and has a shrink finish. May fall. Preferred aliphatic polyesters include polyethylene succinate, polyethylene succinate adipate, polycaprolactone, polyhydroxybutyric acid and the like.

  Moreover, it does not specifically limit as a method to obtain a polylactic acid-type polymer, Well-known methods, such as a condensation polymerization method and a ring-opening polymerization method, are employable. The base material 11 may contain various additives such as a lubricant, a filler, a heat stabilizer, an antioxidant, an ultraviolet absorber, an antistatic agent, a flame retardant, and a colorant as necessary. Good. Moreover, in this embodiment, although the base material 11 is comprised with the single layer, it can also comprise with a multilayer.

  The first print layer 12 is provided in a partial region of the back surface 11 a of the base material 11. In the present embodiment, the first print layer 12 is provided in a partial region of the back surface 11 a of the base material 11, but may be provided over the entire back surface 11 a of the base material 11. The first printed layer 12 includes a base resin having a glass transition point higher than that of the substrate 11 and an inorganic pigment. In the present embodiment, the first printing layer 12 uses a biodegradable resin having a glass transition point higher than that of the base material 11 as a base resin. Specifically, the first printing layer 12 uses a starch-based biodegradable resin (a starch-modified biodegradable resin) as a base resin and titanium oxide as a pigment. Here, the glass transition point of the starch-based biodegradable resin as the base resin is 130 ° C. to 150 ° C., which is higher than the glass transition point of the base material 11.

  The base resin of the first printing layer 12 is not limited to starch-based biodegradable resin, and for example, acrylic resin can be used. In this case, the glass transition point is 60 ° C. to 150 ° C. In addition to titanium oxide, aluminum flakes can be used as the pigment. Incidentally, when titanium oxide is used as the pigment, the first printing layer 12 exhibits white, and when aluminum flakes are used, the first printing layer 12 exhibits silver or gold. In particular, when the pigment is contained in an amount of 10% to 60% by weight, the uneven shape of the substrate 11 is easily obtained, which is preferable.

  The second printed layer 13 is provided in a region where the first printed layer 12 is not provided on the back surface 11 a of the substrate 11. Note that the second print layer 13 may not be provided. Or the 2nd printing layer 13 may overlap with the 1st printing layer 12, and the base material 11 becomes uneven | corrugated shape also in this case. The second printed layer 13 includes a base resin and a pigment having a glass transition point lower than or equivalent to the glass transition point of the substrate 11. In this case, the pigment is not particularly limited, and any pigment can be used, and no pigment can be used. In addition, as base resin, resin which has a glass transition point higher than the glass transition point of the base material 11 can also be used. However, in this case, an organic pigment is used or no pigment is used.

  The shrink label 1 having the above-described configuration is manufactured by manufacturing a base material 11 by a conventional manufacturing method, for example, an extrusion molding method, and matching the first printed layer 12 and the second print on the back surface 11a of the base material 11 according to a desired design. It can be manufactured by forming the printing layer 13 by a known printing method such as gravure printing or flexographic printing. Specifically, first, a resin composition in which other resins and additives are added to a polylactic acid-based resin as necessary is supplied to an extruder equipped with a T die or an annular die and melt-extruded, and then cooled by a cooling roll. After that, the base material 11 is obtained by stretching. The stretching treatment can be performed by either a tenter method or a tube method.

  The stretching may be uniaxial stretching (lateral uniaxial stretching or longitudinal uniaxial stretching) or biaxial stretching, but uniaxial stretching is particularly preferred. In the case of uniaxial stretching, the stretching treatment is performed at a temperature of about 70 ° C. to 100 ° C., for example, in the longitudinal direction of the base material 11 (direction corresponding to the circumferential direction of the container, TD direction), preferably 1.5 to 10 times. By stretching about 2 to 8 times and stretching at a low stretch ratio (for example, about 1.5 times or less) in the width direction of the substrate 11 (direction corresponding to the axial direction of the container, MD direction) as necessary. Done.

  By this stretching treatment, the base material 11 has the heat shrinkability as described above, but the heat shrinkage rate of the base material 11 is the composition of the resin that forms the base material 11, for example, a polylactic acid polymer. It can be adjusted by appropriately selecting the monomer composition, the type and mixing ratio of other resins such as aliphatic polyester to be mixed with the polylactic acid polymer, or the draw ratio during film stretching.

  Next, the first printed layer 12 and the second printed layer 13 are formed by gravure printing in accordance with the desired design on the back surface 11a of the obtained base material 11 (the surface that becomes the inner side when mounted), and described above. A structured shrink label 1 is obtained. In the present embodiment, the first print layer 12 and the second print layer 13 are provided adjacent to each other, but may be provided apart from each other.

  Then, after the obtained shrink label 1 is rounded into a cylindrical shape so that the main stretching direction (longitudinal direction of the base material 11) is the circumferential direction of the container, both ends thereof are connected with an adhesive, a solvent, heat seal, or the like. Then, it is cut to a desired length in the axial direction (length in the width direction of the base material 11), and the base material 11 is made larger than the mouth portion of the container and becomes a cylindrical mold whose diameter is expanded downward. Cap seal 2 is obtained by pre-forming by shrinking.

  In order to attach the cap seal 2 formed from the shrink label 1 having the above configuration to the container, the cap seal 2 is placed over the mouth of the container and thermally contracted. Specifically, the cap seal 2 is covered so that the mouth of the container is fitted into the cylindrical shape of the cap seal 2, and the covered cap seal 2 is heated to a temperature higher than the temperature at which the base material 11 contracts by hot air, steam or the like.

  Then, since the main stretching direction is the circumferential direction (longitudinal direction), the base material 11 tends to shrink in the circumferential direction. At this time, since the first printing layer 12 uses starch-based biodegradable resin as a base resin and titanium oxide which is an inorganic pigment as a pigment, it is difficult to follow the shrinkage of the substrate 11 (that is, the first printing layer is hard). Up to now, the substrate 11 is stretched against contraction in the circumferential direction. When the first printed layer 12 stretches against the shrinkage in the circumferential direction of the base material 11, the base material 11 does not shrink uniformly but shrinks non-uniformly, and thus the first printed layer 12 of the base material 11 after shrinkage. The region corresponding to is uneven in the shrinking direction. As shown in FIG. 2, the uneven shape is formed so as to be uneven in the front and back direction of the base material 11, and is generally formed to wave in the contraction direction (longitudinal direction of the base material 11). Further, the concavo-convex shape has a concavo-convex height of about 0.5 μm to 5 μm and is formed at intervals of 0.1 mm to 1 mm in the shrinking direction. Note that FIG. 2 is a schematic diagram, and the dimensions and ratios of the concavo-convex shapes in the figure do not match the actual ones.

  On the other hand, since the second printed layer 13 contracts following the contraction of the substrate 11, the region of the substrate 11 where the second printed layer is provided contracts uniformly, and after the contraction, a smooth flat surface having no irregularities. Or it becomes a curved surface.

  As described above, when the region of the substrate 11 on which the first printing layer 12 is provided has a concavo-convex shape, the texture of the appearance of the region looks different compared to the case without the concavo-convex shape (for example, matte is applied). As well as the tactile sensation, compared to the case where there is no uneven shape. Therefore, as in the case of the cap seal 2 using the conventional shrink label, after the shrinkage, the entire surface becomes only a smooth surface having no irregularities, and only a uniform decoration effect can be obtained only by the design of the printing layer. In comparison, the decorative effect can be further improved.

  In the shrink label 1 according to the present invention, it is preferable that the softening temperature of the first printing layer 12 is higher than the softening temperature of the substrate 11 in order to obtain a favorable uneven shape. The softening temperature of the second print layer 13 is preferably smaller than the softening temperature of the substrate 11. Here, in this invention, the softening temperature of the base material 11 is a shrink start temperature, and means a temperature at which the base material shrinks by 1% or more when the temperature is raised from room temperature in warm water. Specifically, the softening temperature of a shrink label made of a resin mainly composed of a polylactic acid polymer is 50 ° C. to 60 ° C. Moreover, the softening temperature of a printing layer is the glass transition point of the coating film of a printing layer. Specifically, the softening temperature of the coating film provided with white ink made of a starch-modified biodegradable resin is 85 ° C to 120 ° C. In addition, the glass transition point of the coating film of a printing layer can be measured by DSC method similar to the measuring method of the glass transition point of base resin.

  In the present embodiment, the case where each of the first printing layer 12 and the second printing layer 13 is a single layer has been described. However, the present invention is not limited to this, and each layer may be a multilayer. For example, the first printed layer 12 may be a multilayer in which a silver layer using aluminum flake as a pigment and a white layer using titanium oxide as a pigment are stacked.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.
As the base material 11, a product name “Ecology S” (thickness 50 μm, glass transition point 59 ° C.) of Mitsubishi Plastics Co., Ltd., which is a biodegradable film mainly composed of a polylactic acid polymer, is prepared. No. 12, “Biotech Color HGC White”, a product name of Dainichi Seika Kogyo Co., Ltd., whose base resin is a starch-modified biodegradable resin (glass transition point 130 ° C.) (titanium oxide relative to the total solid content) 30% by weight), and as the second printed layer 13, the base resin is a starch-modified biodegradable resin (glass transition point 130 ° C.) and the color pigment is copper phthalocyanine blue. The product name “Biotech Color HGC Indigo” was prepared.

  Then, the shrink label 1 was obtained by partially providing on the back surface of the substrate 11 so that the first printing layer 12 and the second printing layer 13 do not overlap with each other with a gravure coater. The obtained shrink label 1 was dipped in hot water at 90 ° C., and preformed so that its heat shrinkage rate was 30% in the main stretching direction to obtain a cap seal 2. When the cap seal 2 obtained in this manner is covered with the mouth of the container and thermally contracted, the shape of the region of the substrate 11 where the first printing layer 12 is provided becomes uneven, while the second About the area | region in which the printing layer 13 was provided, it became a smooth shape without much unevenness.

Subsequently, another embodiment will be described.
For the base material 11, the same film as the base material 11 used in Example 1 (trade name “Ecology S” (thickness 50 μm, glass transition point 59 ° C.) of Mitsubishi Plastics, Inc.) is prepared, and the first printing is performed. As the layer 12, a trade name “OSM white” (containing 50% by weight of titanium oxide based on the total solid content) of Dainichi Seika Kogyo Co., Ltd., whose base resin is an acrylic resin (glass transition point 65 ° C.) was prepared. In the present embodiment, the second printing layer 13 is not prepared.

  And the 1st printing layer 12 was partially provided in the back surface of the base material 11 with the gravure coater, and the shrink label 1 was obtained. The obtained shrink label 1 was dipped in hot water at 90 ° C., and preformed so that its heat shrinkage rate was 30% in the main stretching direction to obtain a cap seal 2. When the cap seal 2 obtained in this manner is covered with the mouth of the container and thermally contracted, the shape of the region of the substrate 11 where the first printing layer 12 is provided becomes uneven, and other printing layers About the area | region which was not provided, it became a smooth shape without an unevenness | corrugation at all.

The perspective view which shows the cap seal using the shrink label which concerns on one Embodiment of this invention. Sectional drawing which shows the mode before shrinkage | contraction of the shrink label and the mode after shrinkage | contraction.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Shrink label, 2 ... Cap seal, 11 ... Base material, 12 ... 1st printing layer, 13 ... 2nd printing layer

Claims (3)

Comprising a substrate and a substrate printing provided layer having a heat-shrinkable, at least a portion of the printed layer, viewed contains a base resin and an inorganic pigment having a high glass transition temperature than the glass transition point of the substrate,
The base material is transparent, and a printed layer is formed on the back surface of the base material which is inside when mounted on a container, and the base material in a region corresponding to the printed layer has an uneven shape in the surface direction due to heat shrinkage. shrink label characterized by comprising. The shrink label according to claim 1, wherein the shrinkage stress of the substrate is 5 MPa or less when immersed in hot water at 85 ° C for 10 seconds. 3. The shrink label according to claim 1, wherein the base material is a biodegradable resin mainly composed of polylactic acid.

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