JP2016173931A - Outer packaging label for secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an outer packaging label for a secondary battery, capable of being improved in durability against an external impact, friction, a temperature change or the like.SOLUTION: An outer packaging label 10 for a secondary battery is mounted on a circumference of a substantially cylindrical battery case 21. In the outer packaging label, an external layer 11 comprising a heat-shrinkable film, an internal layer 14 comprising a heat shrink layer, and a pressure sensitive adhesive layer 15 are laminated in the order, and the thermal shrinkage percentages of heat-shrinkable films used in the internal layer and the external layer are set to be substantially equal to each other.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an exterior label for a secondary battery, and more particularly to a technique suitable for use in an exterior label for a secondary battery with improved durability in a rechargeable battery that is used repeatedly.

A dry battery type battery is provided with an outer label provided with a printed layer made of a design, characters, colors, etc. on the outer peripheral surface of a battery case (mainly nickel-plated steel sheet) which contains a power generation element and is sealed. As such an exterior label, a heat-shrinkable label in which a pressure-sensitive adhesive is provided on a heat-shrinkable film having a metal vapor deposition film is known.
For example, Patent Document 1 discloses a laminated material in which a plastic surface layer, an ink layer, a metal vapor-deposited film, and a pressure-sensitive adhesive layer are laminated in this order, and one layer in the laminated material is a heat shrinkable layer. The battery exterior material characterized by this is described.

  In Patent Document 2, another heat-shrinkable resin film is provided on a print layer of a heat-shrinkable resin film having a pressure-sensitive adhesive layer for adhesion to a dry battery body on the back surface and a print layer on the surface. An exterior label for a dry battery, which is laminated and bonded through another adhesive, is described.

  Patent Document 3 discloses a label exterior battery in which a heat-shrinkable resin film is used as a base material and an exterior label having an adhesive layer is attached to the back surface thereof through a metal layer, and the adhesive of the label is a heat-sensitive adhesive. In addition, a label-wrapped battery having a heat-resistant electrical insulating layer between the adhesive layer and the metal layer is described.

Japanese Patent Laid-Open No. 62-177864 JP-A-63-114048 JP 09-237614 A

  Batteries are roughly classified into primary batteries and secondary batteries. The primary battery is a type that can be used once it is completely discharged and then discarded, whereas the secondary battery is a type that can be used repeatedly by charging. Due to its rise, it has become widespread today.

  However, unlike primary batteries, secondary batteries are continually charged and discharged, and are repeatedly inserted and removed from electronic devices and chargers. Durability against rubbing and temperature change is required.

  The present invention has been made in view of the above circumstances, and intends to achieve the object of providing an external label for a secondary battery capable of improving repeated resistance.

The exterior label for a secondary battery of the present invention is an exterior label for a secondary battery attached to the outer periphery of a battery case having a substantially cylindrical shape,
An outer layer made of a heat-shrinkable film;
An inner layer consisting of a heat shrink layer,
A pressure sensitive adhesive layer;
Are stacked in this order,
The above problems have been solved by setting the heat shrinkage rate of the heat shrinkable films used for the inner layer and the outer layer to be substantially equal.
In the outer battery label of the present invention, the difference between the heat shrinkage rate of the heat shrinkable film used for the inner layer and the heat shrinkage rate of the heat shrinkable film used for the outer layer is set to less than 5%. It is more preferable.
In the exterior label for a secondary battery of the present invention, the heat shrink rate of the heat shrinkable film used for the inner layer and the outer layer may be 5% or more at 100 ° C. and 30% or less at 140 ° C.
In the external label for a secondary battery of the present invention, the heat-shrinkable film used for the inner layer and the outer layer is a uniaxially stretched polyethylene terephthalate film, and can shrink in the circumferential direction of the outer periphery of the battery case. is there.
Further, in the exterior label for a secondary battery of the present invention, the metal layer is provided on at least one opposing surface of the inner layer or the outer layer, and the inner layer and the outer layer are bonded by a dry laminate adhesive layer. It is also possible to adopt other means.
Moreover, the exterior label for secondary batteries of this invention WHEREIN: The printing layer can be provided in the surface of the said outer layer.

The exterior label for a secondary battery of the present invention is an exterior label for a secondary battery attached to the outer periphery of a battery case having a substantially cylindrical shape,
An outer layer made of a heat-shrinkable film;
An inner layer consisting of a heat shrink layer,
A pressure sensitive adhesive layer;
Are stacked in this order,
The heat shrinkage rate of the heat-shrinkable film used for the inner layer and the outer layer is set to be approximately equal, so that the secondary battery outer label is attached at least in the axial direction on the outer periphery of the battery case that is substantially cylindrical. After one end is wound so that it protrudes from the case, the overlapping ends are bonded together, and then the part protruding by heat treatment is shrunk to form a battery label so that there is no wrinkle or distortion of the label In addition, even when the battery box is inserted and removed a plurality of times as a secondary battery, it is possible to prevent problems such as peeling, cracking, and elongation of the label. In addition, a metal layer can also be laminated | stacked between an outer layer and an inner layer.

  In the present invention, the difference between the heat shrinkage rate of the heat-shrinkable film used for the inner layer and the heat shrinkage rate of the heat-shrinkable film used for the outer layer is set to less than 5%. The outer label is wound around the outer periphery of the substantially cylindrical battery case so that at least one end in the axial direction protrudes from the case, and the overlapped end portions are bonded together, and then the protruding portion is contracted by heat treatment to form the battery label. When it is formed, it can be molded so that there is no wrinkle or distortion of the label, and even if it is taken in and out of the battery box etc. multiple times as a secondary battery, it will peel off, crack, stretch, etc. Can be prevented from occurring.

  In the present invention, the heat-shrinkable rate of the heat-shrinkable film used for the inner layer and the outer layer is 5% or more at 100 ° C. and 30% or less at 140 ° C. When a cylindrical battery case is wound around the outer periphery of the battery case so that at least one end in the axial direction protrudes from the case, the overlapping ends are bonded together, and then the protruding part is contracted by heat treatment to form a battery label In addition to being able to be molded so that there are no wrinkles or distortions on the label, even if the battery box is inserted and removed multiple times as a secondary battery, defects such as peeling, cracking, and elongation occur on this label. Can be prevented.

  In the exterior label for a secondary battery of the present invention, the heat-shrinkable film used for the inner layer and the outer layer is a uniaxially stretched polyethylene terephthalate film, and shrinks in the circumferential direction of the outer periphery of the battery case. The secondary battery outer label is wound around the outer periphery of the substantially cylindrical battery case so that at least one end in the axial direction protrudes from the case, and the overlapping ends are bonded together, and then the protruding portion is contracted by heat treatment. When it is formed as a battery label, it can be molded so that there is no wrinkle or distortion of the label, and even if it is taken in and out of the battery box etc. multiple times as a secondary battery, it will peel off and crack on this label It is possible to prevent problems such as elongation.

  Further, in the present invention, the metal layer is provided by means in which the metal layer is provided on at least one opposing surface of the inner layer or the outer layer, and the inner layer and the outer layer are bonded by a dry laminate adhesive layer. By forming by vapor deposition and adhering by dry lamination, the secondary battery exterior label is wound around the outer periphery of the battery case that is substantially cylindrical so that at least one end in the axial direction protrudes from the case. After bonding, the part that protrudes by heat treatment is shrunk and formed as a battery label, so that it can be molded so that there is no wrinkle or distortion of the label, and it can be applied to the battery box etc. multiple times as a secondary battery Even when it is taken in and out, it is possible to prevent the label from being peeled, cracked, stretched, and the like.

  Moreover, in the exterior label for secondary batteries of the present invention, the surface of the outer layer is provided with a printing layer, so that the occurrence of ink cracks in the printing layer can be prevented.

  According to the present invention, it is possible to improve durability against external impact, rubbing, temperature change, etc. as an external label for a secondary battery used for a secondary battery that is repeatedly inserted and removed from an electronic device or a charger. An effect can be produced.

It is a schematic cross section which shows 1st Embodiment of the exterior label for secondary batteries which concerns on this invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial cross-sectional front view showing a secondary battery packaged in a first embodiment of a secondary battery exterior label according to the present invention. It is a perspective view which shows the exterior process of the secondary battery by 1st Embodiment of the exterior label for secondary batteries which concerns on this invention. It is a perspective view which shows the exterior process of the secondary battery by 1st Embodiment of the exterior label for secondary batteries which concerns on this invention. It is a perspective view which shows the exterior process of the secondary battery by 1st Embodiment of the exterior label for secondary batteries which concerns on this invention. It is a perspective view which shows the exterior process of the secondary battery by 1st Embodiment of the exterior label for secondary batteries which concerns on this invention.

Hereinafter, a first embodiment of an exterior label for a secondary battery according to the present invention will be described with reference to the drawings.
FIG. 1 is a schematic cross-sectional view showing a secondary battery exterior label in the present embodiment. In the figure, reference numeral 10 denotes a secondary battery exterior label.

  As shown in FIG. 1, a secondary battery exterior label (label) 10 according to the present embodiment is mounted on the outer periphery of a battery case body (battery case) 21 having a substantially cylindrical shape. The label is an outer layer 11 made of a heat-shrinkable film, a metal layer 12, a dry laminate adhesive layer 13, an inner layer 14 made of a heat-shrinkable layer, a pressure sensitive adhesive layer 15, and a release paper 16. They are stacked in order.

As the heat-shrinkable film used for the outer layer 11 and the inner layer 14, a film made of polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polyamide, or the like is used, which is oriented by uniaxial stretching and exhibits large heat-shrinkability in the stretching direction. In addition, a copolymer of these resins can be used as appropriate. In addition, it is preferable to use polyethylene terephthalate from heat resistance, solvent resistance, and repetition durability.
The thickness of the heat-shrinkable film used for the inner layer 14 and the outer layer 11 is preferably set to a range of about 20 to 30 μm. Moreover, it is preferable that the thickness of the heat-shrinkable film used for the inner layer 14 and the outer layer 11 is set to be approximately equal.

The heat shrink rate of the heat shrinkable film used for the inner layer 14 and the outer layer 11 is 5% or more at 100 ° C. and 30% or less at 140 ° C.
When the heat shrinkage rate of the heat shrinkable film is smaller than the above range, for example, less than 5% at 100 ° C. corresponding to 15% or less at 120 ° C., the battery case body 21 is labeled as described later. When attaching 10, the label 10 is shrunk at both terminal portions. At this time, wrinkles may occur and it may not be possible to attach the label 10 well.
In addition, when the heat shrinkage rate of the heat shrinkable film is larger than the above value, for example, when the heat shrinkable film is larger than 30% at 100 ° C. corresponding to 40% or more at 120 ° C., the heat shrinkable film due to heat generation during charging. Due to the effect of re-shrinkage, wrinkles and floating may occur in the secondary battery exterior label 10, which is not preferable. Considering the storage stability when the battery is not used, the heat shrinkage rate of the heat shrinkable film used for the inner layer 14 and the outer layer 11 is preferably 1% or less at 80 ° C.

The heat shrinkage rates of the heat shrinkable films used for the inner layer 14 and the outer layer 11 are set to be approximately equal. Specifically, it is preferable that the difference in heat shrinkage rate between the heat shrinkable films used for the inner layer 14 and the outer layer 11 is set to less than 5%.
If the difference in heat shrinkage between the heat-shrinkable films used for the inner layer 14 and the outer layer 11 is larger than the above range, the battery case body 21 is mounted or stored in a high temperature environment, and is repeatedly attached and detached. When used (during repeated use) or the like, the label 10 may be bent, ink cracks or wrinkles may occur.

The heat-shrinkable film used for the inner layer 14 and the outer layer 11 is a uniaxially stretched polyethylene terephthalate film, and is preferably set to shrink in the circumferential direction of the outer periphery of the battery case body 21 as will be described later.
In this case, the polyethylene terephthalate film may be crystalline or non-crystalline. Amorphous film has a sharper temperature change in thermal shrinkage than a crystalline film and can be mounted in a short time, but is less stable against temperature changes after mounting. Therefore, it can be appropriately determined in consideration of the balance with the heat shrinkage rate.

  The heat-shrinkable film used for the inner layer 14 and the outer layer 11 is a stretch of the heat-shrinkable film in a direction having heat-shrinkability in order to facilitate the formation of the mounted state of the secondary battery exterior label 10 by heat shrinkage. The direction is formed in a direction that wraps around the cylindrical battery case body 21, that is, a direction that coincides with the circumferential direction of the battery case body 21.

In the secondary battery exterior label (label) 10 of the present embodiment, the metal layer 12 is provided at a position sandwiched between the inner layer 14 and the outer layer 11, and specifically, deposited on the inner surface of the outer layer 11. It has been configured.
The metal layer 12 may be made of any metal such as iron, copper, nickel, tin, etc., but aluminum is preferable because it is inexpensive, and it is preferable because formation of the metal layer 12 by vapor deposition is simple.

In the secondary battery exterior label (label) 10 of the present embodiment, an outer layer 11 provided with a metal layer 12 and an inner layer 14 are bonded by a dry laminate adhesive layer 13.
As an adhesive for bonding the outer layer 11 and the inner layer 14, a normal adhesive used for dry lamination can be used. Unlike the pressure-sensitive adhesive described later, the adhesion between the outer layer 11 and the inner layer 14 is not required to have tackiness, and from the viewpoint of heat resistance, solvent resistance, and repeated durability. preferable.

In the secondary battery exterior label (label) 10 of the present embodiment, a printing layer 17 composed of a desired design, characters, colors, and the like is appropriately provided on the surface of the outer layer 11.
The printing layer 17 is formed by using a generally known thermosetting ink or ultraviolet curable ink by a generally known printing method, for example, letterpress printing, offset printing, silk screen printing, gravure printing, or the like. It is.
Furthermore, in order to protect this printing layer 17, you may form a protective layer with the varnish etc. which provide abrasion resistance to the printing layer 17 surface side.
In addition, primer treatment, anchor treatment, or the like is appropriately performed between the outer layer 11 and the printing layer 17, so that fixing properties and adhesion between the outer layer 11 and the printing layer 17 can be improved. As the anchor coat, for example, polyolefin-based, polyurethane-based, acrylic-based anchors, and as the primer coating agent, known agent types such as a polyester-based primer and a two-component mixed isocyanate-based primer can be used.

  In the secondary battery exterior label 10 of the present embodiment, a pressure-sensitive adhesive layer 15 for closely contacting the battery case body 21 is provided on the back surface of the inner layer 14. The pressure-sensitive adhesive layer 15 is made of, for example, a main ingredient such as an acrylic ester, an acrylic acid copolymer, or natural rubber, a tackifier such as ester gum, rosin, or coumarone, or a plastic such as polybutene, dioctyl phthalate, or castor oil. What mix | blended the agent etc. can be used.

  The secondary battery exterior label 10 of the present embodiment is cut into a predetermined size and contour and is attached to the release paper 16.

  Hereinafter, the usage example of the exterior label 10 for secondary batteries of this embodiment is demonstrated.

  FIG. 2 is a partial cross-sectional front view showing the secondary battery packaged with the secondary battery exterior label in the present embodiment, and FIGS. 3 to 6 are secondary battery exterior labels in the present embodiment. It is a perspective view which shows the exterior process of the secondary battery by.

  As shown in FIG. 2, the secondary battery exterior label 10 of the present embodiment is wound around and attached to a cylindrical battery case body 21 of the secondary battery 20. Further, the outer peripheral label 10 for the secondary battery is in close contact with each of the upper and lower end surfaces 21a and 21b of the battery case body 21 where the electrodes 22 and 23 are provided.

  In order to package the secondary battery exterior label 10 of the present embodiment on the secondary battery 20, first, as shown in FIG. 3, the pressure sensitivity is applied to the secondary battery exterior label 10 peeled from the release paper 16. The battery case body 21 of the secondary battery 20 is rotated so as to contact the surface of the adhesive layer 15, and as shown in FIG. 4, the secondary battery extends in the circumferential direction of the battery case body 21 of the secondary battery 20. The outer packaging label 10 is wound and stuck.

  At this time, the shrink direction (uniaxial stretching direction) as the heat shrink film in the secondary battery exterior label 10 is set so as to coincide with the circumferential direction of the outer periphery of the battery case body 21 of the secondary battery 20. At the same time, as shown in FIG. 5, the edge portion 10b on the end side is overlapped and bonded to the edge portion 10a of the secondary battery exterior label 10 on the winding start end side.

  Thereafter, as shown in FIG. 6, the projecting portions 10 c and 10 d projecting outward from the both end faces 21 a and 21 b of the battery case body 21 with the electrodes 22 and 23 are heat-treated to be thermally contracted, and used for a secondary battery. The exterior label 10 is attached in close contact with the peripheral surface of the battery case body 21 and the peripheral edges of both end surfaces 21a, 21b.

  As described above, the outer battery label 10 for the secondary battery according to the present embodiment has the heat shrinkable film thickness and heat shrinkage rate used for the inner layer 14 and the outer layer 11 set to be approximately equal to each other. When shrinking closely to the periphery, it can be suitably shrunk without generating wrinkles, etc., and is durable against external impacts, rubbing, temperature changes, etc. in secondary batteries that are repeatedly inserted and removed from electronic devices and chargers Can be improved.

In the present embodiment, the metal layer 12 is formed on the inner surface of the outer layer 11, but the metal layer 12 may be formed on the outer surface of the inner layer 14. In this case, the metal layer 12 may not be formed on the inner surface side of the outer layer 11.
Moreover, in the battery case trunk | drum 21, either the surface by the side of the end surface 21a or the end surface 21b can also be not covered with the exterior label 10 for secondary batteries.

  Examples according to the present invention will be described below.

<Experimental example 1>
A uniaxially stretched heat-shrinkable film made of polyethylene terephthalate having a thickness of 30 μm was prepared as the outer layer film used for the outer layer 11. This uniaxially stretched heat-shrinkable film made of polyethylene terephthalate has a heat shrinkage rate of 8% at 100 ° C. and 28% at 140 ° C.
A metal layer 12 made of aluminum having a thickness of 50 nm was formed on one surface of the outer layer film using a resistance heating vacuum deposition apparatus.

Next, an anchor layer made of a thermosetting polyester resin having a thickness of 1.0 μm was formed on the surface opposite to the metal layer 12 of the outer layer film using a gravure printing machine.
Further, a dry laminate adhesive layer 13 made of a thermosetting polyurethane resin having a thickness of 3 μm was formed on the metal layer 12 of the outer layer film using a gravure printing machine.

  As the inner layer film, a uniaxially stretched heat-shrinkable film made of polyethylene terephthalate having the same thickness as the above-described outer layer film and having a thickness of 30 μm was prepared and bonded so that the shrinking directions (stretching directions) thereof were matched.

  A pressure-sensitive adhesive paper having a pressure-sensitive adhesive layer 15 made of an acrylic resin having a thickness of 25 μm is prepared on the release paper 16, and the laminated film is pressure-sensitive on the inner layer side opposite to the outer layer. The adhesive layer 15 was bonded.

  Finally, a printed layer 17 made of ultraviolet curable ink and a protective layer made of varnish are formed on the anchor layer of the outer layer film, and the outer layer film from the pressure-sensitive adhesive layer 15 to the printed layer 17 side has a predetermined shape. Then, if necessary, unnecessary portions were peeled off (cast), and Experimental Example 1 of the secondary battery exterior label 10 was obtained.

<Experimental example 2>
As the inner layer film, a secondary battery outer label was prepared in the same manner as in Experimental Example 1 except that an ethylene vinyl acetate copolymer resin (EVA, incompressible) having a thickness of 30 μm was extruded and coated onto the outer layer film. It was set as Experimental example 2.

<Experimental example 3>
Experimental Example 1 except that a 30 μm thick uniaxially stretched heat-shrinkable film made of polyethylene terephthalate having a heat shrinkage rate of 3% at 100 ° C. and 23% at 140 ° C. was used as the outer layer film and the inner layer film. In the same manner as above, an external label for a secondary battery was prepared and used as Experimental Example 3.

<Experimental example 4>
Experimental Example 1 except that a 30 μm-thick uniaxially stretched heat-shrinkable film made of polyethylene terephthalate having a heat shrinkage rate of 30% at 100 ° C. and 65% at 140 ° C. was used as the outer layer film and the inner layer film. In the same manner as above, an external label for a secondary battery was prepared and used as Experimental Example 4.

<Evaluation>
The following evaluation was performed about the exterior label for secondary batteries of each experimental example.

<Evaluation method>
・ Environmental test: Store in a high temperature environment at 100 ° C. for 24 hours, and visually check for floating, wrinkles and peeling.
-Desorption test: In a 25 ° C environment, the battery charger is repeatedly inserted and removed at the same location, and the number of times until floating, wrinkling, and peeling occur is counted.
Shrink test: After being attached to the battery case body 21, the labels 10c and 10d on both ends 21a and 21b on the electrode side are shrunk by heat treatment, and the battery case body 21 and both ends 21a and 21b are Visually check whether it is covered in close contact without floating.
Here, an AA type secondary battery was used.
The results of these tests are shown in the table.

<Evaluation results>

As shown in the table, in Example 2, the adhesion between the battery case and the inner layer was good, but tearing occurred in the desorption test.
In Experimental Example 3, since the heat shrinkage rate of the inner layer film was low, the film did not shrink well and wrinkles occurred on both end surfaces of the battery case body.
In Experimental Example 4, the occurrence of peeling was confirmed in the environmental test.

  On the other hand, Experimental Example 1 has no problem in any of the environmental test, the desorption test, and the shrink test, and is the same as Experimental Examples 3 and 4 in the desorption test, but was confirmed to be the best.

DESCRIPTION OF SYMBOLS 10 ... Secondary battery exterior labels 10a, 10b ... Edges 10c, 10d ... Projection 11 ... Outer layer 12 ... Metal layer 13 ... Dry laminate adhesive layer 14 ... Inner layer 15 ... Pressure sensitive adhesive layer 16 ... Release paper 17 ... Printing Layer 20 ... secondary battery 21 ... battery case body (battery case)
21a, 21b ... end faces 22, 23 ... electrodes

Claims (6)

A secondary battery outer label attached to the outer periphery of the battery case having a substantially cylindrical shape,
An outer layer made of a heat-shrinkable film;
An inner layer consisting of a heat shrink layer,
A pressure sensitive adhesive layer;
Are stacked in this order,
A heat-shrinkable film used for the inner layer and the outer layer has a heat shrinkage rate set to be approximately equal.   The difference between the heat shrinkage rate of the heat-shrinkable film used for the inner layer and the heat shrinkage rate of the heat-shrinkable film used for the outer layer is set to less than 5%. Secondary battery exterior label.   3. The secondary battery according to claim 1, wherein the heat shrink rate of the heat shrinkable film used for the inner layer and the outer layer is 5% or more at 100 ° C. and 30% or less at 140 ° C. 3. Exterior label.   The heat shrinkable film used for the inner layer and the outer layer is a uniaxially stretched polyethylene terephthalate film, and shrinks in the circumferential direction of the outer periphery of the battery case. Secondary battery exterior label.   The metal layer is provided on at least one opposing surface of the inner layer or the outer layer, and the inner layer and the outer layer are bonded to each other by a dry laminate adhesive layer. An exterior label for a secondary battery as described above.   The exterior label for a secondary battery according to any one of claims 1 to 5, wherein a printed layer is provided on a surface of the outer layer.

Images