JP2020097435A - Overwrap film and overwrap package - Google Patents

Abstract

To provide an overwrap film allowing continuous production of an overwrap package without generation of sparks during electrostatic sealing.SOLUTION: An overwrap film 1 comprises: an elongated film base material 2 having a pair of side end parts 21 and 22 joined by electrostatic sealing; and a colored part 3 provided on a portion of at least one side end part 21 of the pair of side end parts 21 and 22. An electric resistance value RA of a portion having no colored part in the side end part 21 is 1.0×10Ω or more, and the electric resistance value RA of the portion having no colored part in the side end part 21 and an electric resistance value RB of the portion having the colored part 3 satisfy a relationship of 0<RA/RB≤10.SELECTED DRAWING: Figure 9

Description

The present invention relates to an overwrap film and an overwrap package for wrapping articles.

The overlap film is a packaging material used for packaging various items such as containers containing foods and daily necessities.
For example, by using a horizontal pillow wrapping machine, the overlap film is covered so as to wrap the article, so that the overlap film is attached to the article.
An overwrap package in which articles are packaged with an overwrap film is usually manufactured continuously using a horizontal pillow packaging machine. A long strip-shaped overlap film, a pair of side end portions along the longitudinal direction while joining the article to form a tubular shape is joined, and the long strip-shaped overlap film formed into a tubular shape to wrap the article. After performing the heat-sealing in the width direction on both the front and rear sides of the article, the article is encapsulated inside and the three-sided overlapped film is heated to cause heat shrinkage to obtain an overlap package. Such a packaging form is also called horizontal pillow packaging, and the overlap film can be said to be a film for horizontal pillow packaging.

As a method of joining a pair of side end portions of the overlap film, a heat seal and an electrostatic seal are typically known. The heat sealing is a method of joining while melting the side end portions of the film, and the electrostatic sealing is a method of artificially joining the side end portions of the film by the action of static electricity. The electrostatic seal has the advantages that no film cutting residue is produced and the appearance of the joint is relatively clean.
Patent Document 1 discloses a packaging machine having an electrostatic sealing device for overlapping films. This electrostatic sealing device is configured so that the positive and negative electrodes can be displaced in order to prevent sparks from being generated between the positive and negative electrodes.

Japanese Patent Publication No. 63-17696

However, when the pair of side edges of the overlap film are electrostatically sealed, sparks may occur at the side edges themselves of the overlap film. When sparks are generated at the side edges during electrostatic sealing as described above, an overlapping package having defective joints can be obtained. Furthermore, in the process of manufacturing the overlap package, the long strip-shaped overlap film may be broken, and the overlap package may not be continuously manufactured.

A first object of the present invention is to provide an overwrap film capable of continuously producing an overwrap package without generating sparks during electrostatic sealing.
A second object of the present invention is to provide an overwrap package in which a pair of side ends are neatly joined by electrostatic sealing.

The present inventors have examined the cause of sparking of the conventional overlapping film during electrostatic sealing from various viewpoints. Among them, the present invention was completed by finding out that the colored portion is the cause of the spark of the overlapping film.
Specifically, the colored portion is a portion with a color that can be distinguished from the other portions. The colored portion is used as, for example, a mark that serves as an index for aligning the cutting position and the printing position of the long strip-shaped overlap film. For example, the mark sensor provided in the packaging machine optically detects the colored portion of the overlapping film conveyed on the line, and based on the detection result, the long strip-shaped overlapping film is positioned at a predetermined position. It will be disconnected. The colored portion detected by such a mark sensor is also particularly called a phototube mark portion. Since the photoelectric tube mark portion is a mark that is necessary for manufacturing the overlap package and is not related to the design of the overlap package, it is partially provided at the side end portion of the overlap film. It has been found that sparks may occur at the phototube mark portion during electrostatic sealing. Conventionally, the phototube mark portion is composed of a black printing portion printed with black ink. The black ink contains a pigment having good electric conductivity such as carbon black, and therefore, the photoelectric tube mark portion has a small electric resistance value. On the other hand, the film base material forming the overlap film has a relatively large electric resistance value. The present invention has been completed by identifying the occurrence of sparks due to the partial presence of the phototube mark portion having a small electric resistance value in the side end portion having a large electric resistance value.

The overlap film of the present invention is provided on a long strip-shaped film substrate having a pair of side end portions that can be joined by electrostatic sealing, and a part of at least one side end portion of the pair of side end portions. The colored portion of the side end has an electric resistance value RA of 1.0×10 ¹⁵ Ω or more. The electric resistance value RA of the portion not having it and the electric resistance value RB of the portion having the colored portion satisfy the relation of 0<RA/RB≦10.

In the preferable overlap film of the present invention, the pair of side end portions of the film base material are directly joined by electrostatic sealing.
The preferred overlapping film of the present invention, the pair of side end portions is composed only of a colorless transparent film substrate, the colored portion is composed of a colored printing layer other than black printed on the side end portion. ing.
In the preferred overlap film of the present invention, the colored portion does not substantially contain carbon black.

According to another aspect of the present invention, an overlap package is provided.
The overlap package of the present invention is an overlap film having an article, a film base material, and a colored portion provided at a part of at least one side end portion of a pair of side end portions of the film base material. And an overlap film in which the pair of side ends are joined by electrostatic sealing, the article is packaged in the overlap film, and the side end does not have a colored portion. The electric resistance value RA of the portion is 1.0×10 ¹⁵ Ω or more, and the electric resistance value RA of the side end portion not having the colored portion and the electric resistance value RB of the portion having the colored portion. Satisfies the relationship of 0<RA/RB≦10.

According to the overlap film of the present invention, electrostatic sealing can be performed without causing sparks. By using such an overlap film, it is possible to continuously manufacture an overlap package in which side edges are neatly joined by electrostatic sealing.

The partially omitted plan view of the long strip-shaped overlap film according to one embodiment as seen from the front surface side. FIG. 3 is an enlarged plan view of one sheet-shaped overlapping film cut out from a long strip-shaped overlapping film as seen from the front surface side. Sectional drawing cut|disconnected by the III-III line of FIG. Sectional drawing cut|disconnected by the IV-IV line of FIG. The partially omitted enlarged plan view showing a specific example of the arrangement of the colored portions of the overlap film according to another embodiment. FIG. 6 is a schematic side view showing a step of packaging an article using a long strip-shaped overlap film. The overlap packaging body which concerns on one Embodiment is shown, (a) is the top view, (b) is the rear view, (c) is the right side view, (d) is the left side view. .. The expanded sectional view cut|disconnected by the VIII-VIII line of Fig.7 (a). The expanded sectional view cut|disconnected by the IX-IX line of FIG.7(c). It is the schematic which shows the measurement procedure of an electric resistance value, (a) is a schematic front view of the sample mounting site|part of the used resistance measuring device, (b) is the schematic plan view which looked at the support plate from the arrow Xb direction. , (C) is a schematic plan view of the pair of electrodes as seen from the direction of the arrow Xc, (d) is a schematic front view showing the process of installing the sample, and (e) is the measurement sample installed on the attachment site. A schematic cross-sectional view showing a state, (f) is a schematic cross-sectional view showing a state in which a measurement sample is installed at a mounting site, FIG. 3 is a partially omitted plan view of the overlap film produced in the examples as seen from the front surface side.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
However, in the present specification, the “rear surface” refers to the surface on the article side when the overlap film is attached to the article, and the “front surface” refers to the surface on the side opposite to the back surface.
The numerical range represented by "lower limit value X to upper limit value Y" means a lower limit value X or more and an upper limit value Y or less. When a plurality of the numerical ranges are described separately, it is possible to select an arbitrary lower limit value and an arbitrary upper limit value and set "an arbitrary lower limit value to an arbitrary upper limit value".
It should be noted that the shapes and sizes shown in each drawing, the thickness of each layer, and their relative proportions are different from the actual dimensions.

<Structure of overlap film>
FIG. 1 shows a long strip-shaped overlap film 1, and FIG. 2 shows an overlap film 11 having a size for packaging one article. In the mechanical production process, the overlap film 1 is usually supplied in the form of an elongated body as shown in FIG. 1 and conceptually cut into a size enough to package one article. The chain double-dashed line in FIG. 1 indicates the planned cutting line of the long strip-shaped overlap film 1, and the sheet-shaped overlapping film 11 cut at this planned cutting line is the overlapping film 11 shown in FIG. Is. In other words, the long strip-shaped overlap film 1 is formed by continuously connecting a plurality of overlap films 11 each having a size capable of packaging one article.
The long strip shape means a substantially rectangular shape in plan view whose length in the longitudinal direction is sufficiently longer than that in the lateral direction. As the long strip, for example, the length in the longitudinal direction is 5 m or more (preferably 10 m or more), and the length in the lateral direction is 100 mm to 1000 mm. The short-side direction is a direction orthogonal to the long-side direction.

As shown in FIGS. 3 and 4, the long strip-shaped overlap film 1 (including the sheet-like overlap film 11) has a heat-shrinkable film base material 2 and side edges of the film base material 2. And a colored portion 3 provided on the film base 2, and the design printing layer 4 is provided on the film substrate 2 as needed. The colored portion 3 is a colored portion that distinguishes a portion provided with the colored portion and a portion not provided with the colored portion in the side end portion of the film substrate 2. The colored portion 3 is used, for example, as a reading mark by a mark sensor, as described later.
In FIGS. 1 and 2, for the sake of convenience, the area of the film base material 2 in which the colored portion 3 is provided is shaded, and the area of the film base material 2 in which the design print layer 4 is provided is innumerable. Is attached (same for FIG. 5).

The film base material 2 having heat shrinkability has a long strip shape. The heat shrinkability refers to a property of not shrinking substantially at room temperature, but shrinking when heated to a heat shrinking temperature (for example, 70° C. to 100° C.). The film substrate 2 is not particularly limited as long as it has heat shrinkability and flexibility, and a conventionally known synthetic resin film can be used.
Examples of the material of the synthetic resin film include olefin resins such as polyethylene and polypropylene, polyester resins such as polyethylene terephthalate and polylactic acid, styrene resins such as polystyrene and styrene-butadiene copolymer, and vinyl chloride resins. A thermoplastic resin may be used, and an olefin resin such as a polyethylene resin is preferably used. The synthetic resin film may have a single-layer structure or a multi-layer structure. Examples of the synthetic resin film having a multi-layer structure include a film including a surface resin layer/intermediate resin layer/back surface resin layer. In this case, at least the surface resin layer and the back surface resin layer are olefins such as polyethylene resin. It is preferably a resin.
Further, as the film base material 2 having heat shrinkability, a synthetic resin film in which a gas or/and light barrier layer, an anchor coat layer and the like are laminated may be used.

The film substrate 2 may contain various additives. Examples of the additives include fillers, heat stabilizers, antioxidants, lubricants, nucleating agents, flame retardants and the like. Generally, an antistatic agent is known as an additive for a film, but since the antistatic agent may reduce the electrostatic sealing property of the film base material 2, the antistatic agent should not be substantially contained in the film base material 2. Preferably.
When the additive is blended, the amount thereof is preferably more than 0 and 50% by weight or less in the whole film base material 2.

The film substrate 2 may be either transparent (transparent means colored transparent or colorless transparent) or opaque from the viewpoint of translucency, but a transparent film substrate 2 is preferable, and a colorless transparent film substrate. 2 is more preferable. Examples of the colorless and transparent film substrate 2 include a colorless and transparent synthetic resin film, a colorless and transparent synthetic resin film in which a colorless and transparent gas or/and light barrier layer is laminated, and the like. Examples of the colored and transparent film substrate 2 include a lightly colored synthetic resin film.
As the index of transparency (colorless transparency or colored transparency), for example, the total light transmittance can be used. Transparent (colorless transparent or colored transparent) has, for example, a total light transmittance of 70% or more, preferably 80% or more, and more preferably 90% or more. However, the total light transmittance refers to a value of the transparent film substrate 2 measured by a measuring method according to JIS K7361 (Plastic-Testing method for total light transmittance of transparent material).
The thickness of the film substrate 2 is not particularly limited and is, for example, 8 μm to 80 μm, preferably 10 μm to 60 μm.

The heat-shrinkable synthetic resin film is obtained by a known film forming method. For example, a resin composition obtained by mixing a synthetic resin and various additives as necessary is mixed by a mixer or the like, melted using an extruder, extruded from a T-die, stretched and heat-set. be able to. The stretching treatment may be either a tenter method or a tube method. The stretching treatment is usually performed at a temperature of about 70 to 110° C. independently in the longitudinal direction (for example, MD direction during film formation) and the lateral direction (TD direction during film formation) of 2.0 to 8. It is carried out by stretching 0 times (preferably about 3.0 to 7.0 times). The stretching treatment can impart heat shrinkability to the film.

The heat shrinkage rate at 100° C. in the longitudinal direction and the transverse direction of the film substrate 2 is not particularly limited, but is, for example, each independently 10% or more, and preferably 20% or more.
However, the heat shrinkage rate at 100° C. refers to that measured according to JIS Z 1709.

A colored portion 3 is provided on a side end portion of the film base material 2. The side end portions of the film base material 2 are the side end portions 21 and 22 of the long strip-shaped film base material 2 that extend along the longitudinal direction (the side end portions 21 and 22 are conceptually the longitudinal direction. It is a strip that extends to). A pair of side edges 21 and 22 of the film base 2 face each other in the lateral direction.
The pair of side end portions 21 and 22 of the film base material 2 (side end portions 21 and 22 of the overlap film 1) are portions that are overlapped with each other when packaging an article and can be joined by electrostatic sealing. By the electrostatic seal, one of the front and back surfaces of the one side end 21 is joined to one of the front and back surfaces of the other side end 22. That is, each one surface of the pair of side end portions 21 and 22 is a joint surface joined by electrostatic sealing.
The pair of side end portions 21 and 22 are a part of the film base material 2 and are designed portions that can be joined by electrostatic sealing. In order to make the side end portions 21 and 22 easy to understand, in FIG. 2, for convenience, the conceptual virtual boundary lines L1 and L2 of the pair of side end portions 21 and 22 are shown by small broken lines (also in FIG. 5). .. However, the actual overlapping film 1 (film base material 2) does not necessarily show broken lines or mark lines indicating the side end portions 21 and 22.
The widths W21 and W22 of the pair of side end portions 21 and 22 (the width of the side end portions refers to the length in the lateral direction) are not particularly limited, but are, for example, 5 mm to 25 mm, preferably 7 mm to 15 mm. Is set to.
The width of the portion that can be joined by the electrostatic seal (joint portion of the overlapping package) is equal to the width of one side end portion 21. However, when electrostatically sealing, there is a case where the pair of side end portions 21 and 22 do not exactly coincide with the design value and do not overlap, so the actual width of the joint portion of the overlapping package is Note that it may differ from the width of the end 21.

The colored portion 3 is provided on a part of at least one side end portion of the pair of side end portions 21 and 22 of the film base material 2. For example, the colored portion 3 may be provided only on one side end portion, or may be provided on both the pair of side end portions 21 and 22. In the illustrated example, the colored portion 3 is provided on a part of each of the pair of side end portions 21 and 22. Hereinafter, of the pair of side end portions 21 and 22, one is referred to as a “first side end portion 21 ”and the other is referred to as a “second side end portion 22 ”, which is a color provided on the first side end portion 21. The part 3 may be referred to as the "first colored part 31", and the colored part 3 provided at the second side end 22 may be referred to as the "second colored part 32".

In the long strip-shaped film base material 2 (long strip-shaped overlapping film 1), the colored portion 3 is included in order to include at least one colored portion 3 in one sheet-shaped overlapping film 11. Are provided repeatedly at a predetermined interval in the longitudinal direction of at least one side end portion (this interval corresponds to the length of one sheet-shaped overlap film 11).

One (one) first colored portion 31 may be provided corresponding to one sheet-shaped overlapping film 11, or two or more first colored portions 31 may be provided. Good. In the case where two or more first colored portions 31 are provided corresponding to one sheet-shaped overlap film 11, the film base 2 is a long strip (long strip overlap film 1). The two or more first colored portions 31 are repeatedly provided at regular intervals in the longitudinal direction.
One (one) second colored portion 32 may be provided corresponding to one sheet-shaped overlap film 11, or two or more second colored portions 32 may be provided. Good. In the case where two or more second colored portions 32 are provided corresponding to one sheet-shaped overlap film 11, the film is provided in the long strip-shaped film substrate 2 (long strip-shaped overlap film 1). The two or more second colored portions 32 are repeatedly provided at regular intervals in the longitudinal direction.

In the illustrated example, one first colored portion 31 is provided corresponding to one sheet-shaped overlap film 11, and the first colored portion 31 is repeatedly provided at the first side end portion 21 with a constant interval. Has been. Further, one second colored portion 32 is provided corresponding to one sheet-shaped overlapping film 11, and the second colored portion 32 is repeatedly provided at the second side end portion 22 with a constant interval. There is.

The first colored portion 31 and the second colored portion 32 may be arranged so as to face each other in the lateral direction as in the illustrated example, or, although not particularly shown, they may not face each other in the lateral direction.
The planar view shape of the colored portion 3 (the first colored portion 31 and the second colored portion 32) is not particularly limited and is generally formed in a substantially rectangular shape (or a substantially square shape) in a planar view. Although the long axis of the colored portion 3 having a substantially rectangular shape in plan view may be along the longitudinal direction of the film substrate 2 (not shown), for example, in order to detect an accurate position with a mark sensor. Usually, as in the illustrated example, the major axis is formed along the lateral direction of the film substrate 2.
Specific dimensions of the colored portion 3 having a substantially rectangular shape in plan view include, for example, a short axis length of 2 mm to 7 mm and a long axis length of 7 mm to 20 mm.

It is sufficient that the first colored portion 31 and the second colored portion 32 are provided so that at least a part thereof is included in the first side end portion 21 and the second side end portion 22. For example, as shown in FIG. 2, the first colored portion 31 and the second colored portion 32 may be provided on the first side end portion 21 and the second side end portion 22 without excess or deficiency in the lateral direction. In one embodiment shown in FIG. 2, the first colored portion 31 is provided from the side edge 21a of the first side end portion 21 to the virtual boundary line L1 of the first side end portion 21, and the second colored portion 32 is It is provided from the side edge 22a of the second side end 22 to the virtual boundary line L2 of the second side end 22.

Further, in another embodiment, the first colored portion 31 and the second colored portion 32 may be provided in a range smaller than the width of the first side end portion 21 and the second side end portion 22 in the lateral direction. Alternatively, it may be provided so as to extend beyond the first side end portion 21 and the second side end portion 22 and protrude to the respective neighboring portions of the first side end portion 21 and the second side end portion 22. 5A to 5D show an overlap film 1 according to another embodiment in which the arrangement of the colored portion 3 is changed. However, in FIG. 5, only the first side end portion 21 of the sheet-shaped overlap film 11 and the vicinity thereof are shown, and the others are omitted.

For example, as shown in FIG. 5A, the first colored portion 31 extends from the side edge 21a of the first side end portion 21 to the front of the virtual boundary line L1 of the first side end portion 21 (from the virtual boundary line L1. (Not shown), or, as shown in FIG. 2B, from the virtual boundary line L1 of the first side end 21 to the side edge 21a of the first side end 21 (side edge). 21a) may be provided, or as shown in (c) of the figure, it may be provided only in the lateral center portion of the first side end portion 21. Further, as an example in which the first colored portion 31 is provided beyond the boundary of the first side end portion 21 to the vicinity of the first side end portion 21, for example, as shown in FIG. When the colored portion 31 is provided in the vicinity of the first side end portion 21 from the side edge 21a of the first side end portion 21 beyond the virtual boundary line L1 of the first side end portion 21, otherwise not shown. However, the first colored portion 31 is provided in the vicinity of the first side end portion 21 from before the side edge 21a of the first side end portion 21 beyond the virtual boundary line L1 of the first side end portion 21. Cases are included. The vicinity of the first side end 21 refers to a range of 10 mm inward from the virtual boundary line L1 of the first side end 21.

The width of the first colored portion 31 (the length in the lateral direction of the first colored portion 31) is not particularly limited, but is preferably 0.5 to 1.5 times the width of the first side end portion 21. It is more preferable that the width is 0.7 times to 1.2 times the width of the first side end portion 21.
As in the illustrated example, in the colored portion 3 having a substantially rectangular shape in plan view in which the major axis is arranged along the lateral direction, the major axis length corresponds to the width of the first colored portion 31.

Specific examples of other embodiments of the second colored portion 32 are similar to specific examples of other embodiments of the first colored portion 31. In the description of the other embodiments of the first colored portion 31, the “first colored portion 31 ”, the “first side end portion 21 ”, the “side edge 21 a ”, and the “virtual boundary line L1” are respectively referred to as “second A specific example of another embodiment of the second colored portion 32 shall be described by substituting the “colored portion 32 ”, the “second side end portion 22 ”, the “side edge 22 a ”, and the “virtual boundary line L 2 ”. ..
The arrangement of the first colored portion 31 and the second colored portion 32 is not limited to the same case and may be different from each other. For example, as shown in FIG. 2, the first colored portion 31 is provided on the first side end portion 21 without excess or deficiency in the lateral direction, and the second colored portion 32 is as shown in FIGS. It may be provided in an arrangement.

It is preferable that the colored portion 3 does not substantially contain a substance having good conductivity such as carbon black. When a material having good conductivity is contained, it becomes difficult to form the colored portion 3 that satisfies the relationship of 0<RA/RB≦10 described later.
Here, in the present specification, substantially not containing "AAA" means that a trace amount of "AAA" which is inevitably contained is allowed and a significant amount of the mixture is excluded. ..
The method of configuring the colored portion 3 is not particularly limited, and for example, the overlapping film 1 may be formed so that a color is imparted to a part of the overlapping film itself (a portion forming the colored portion 3). Since the colored portion 3 can be easily formed, it is preferable that the colored portion 3 is formed of a colored printing layer, and it is more preferable that the colored portion 3 is formed of a colored printing layer other than black. It is preferable that the colored printing layer also does not substantially contain a substance having good conductivity such as carbon black.
The colored printing layer (colored portion 3) can be formed by printing a color ink on the side end portion of the film substrate 2 by a conventionally known printing method such as a gravure printing method.
The thickness of the colored printing layer (colored portion 3) is not particularly limited and is, for example, 0.1 μm to 5 μm.

The color of the colored printing layer (colored portion 3) is preferably other than black as described above. For example, according to the three primary colors, cyan, magenta, yellow, and two or more types selected from these Color mixing is mentioned. One kind selected from cyan, magenta, and yellow is preferable because the colored portion 3 is unlikely to generate sparks during electrostatic sealing, and cyan is more preferable because it is easily detected by the mark sensor.
The colored printing layer is composed of an ink solidified film formed by printing color ink. The colorant contained in the color ink is not particularly limited, but it is preferable to be one other than the carbon black type, and for example, an organic pigment type that develops a color other than the black color is used.

The colored portion 3 is provided on either the back surface or the front surface of the film substrate 2, or is provided on both the back surface and the front surface of the film substrate 2.
Preferably, the colored portion 3 is provided only on the back surface of the film substrate 2 as shown in FIGS. 3 and 4.

The design printing layer 4 is provided on the film substrate 2 as needed.
The design printing layer 4 is a printing layer in which designs such as product names and designs are represented by one color or multiple colors. The design printing layer 4 can be formed by printing a conventionally known color ink on the film substrate 2 by a conventionally known printing method such as a gravure printing method.
The thickness of the design print layer 4 is not particularly limited and is, for example, 0.1 μm to 5 μm.
The design print layer 4 is provided on either the back surface or the front surface of the film substrate 2, or is provided on both the back surface and the front surface of the film substrate 2. Preferably, the design printing layer 4 is provided only on the back surface of the film substrate 2 as shown in FIG.

The design printing layer 4 may be provided over the entire film substrate 2, or may be provided on a part of the film substrate 2.
Since the pair of side end portions 21 and 22 of the film base material 2 can be directly electrostatically sealed, the design printing layer 4 is a range excluding the joint surface of the pair of side end portions 21 and 22 of the film base material 2. Of the film base material 2 is preferably provided on all or a part of the film base material 2 excluding the pair of side end portions 21 and 22, and more preferably on one side of the film base material 2. It is provided in all or a part of the range excluding the end portions 21 and 22 and the vicinity of the side end portions thereof.
Further, since the heat-sealing can be satisfactorily performed, it is preferable that the design printing layer 4 is provided in the whole or a part of the range excluding the planned cutting line and its vicinity, as shown in FIG. ..

<Electrical resistance value of overlap film>
In the overlap film 1 of the present invention, the electric resistance value RA of the side end portion which does not have the colored portion 3 is 1.0×10 ¹⁵ Ω or more, and the portion which does not have the colored portion 3. The electric resistance value RA and the electric resistance value RB of the portion having the colored portion 3 satisfy the relationship of 0<RA/RB≦10. Hereinafter, a portion of the side end portion that does not have the colored portion 3 may be referred to as an “absent portion”, and a portion of the side end portion that has the colored portion 3 may be referred to as a “present portion”.
As described above, in the case where the colored portion 3 is provided on each of the first side end portion 21 and the second side end portion 22 (the pair of side end portions 21 and 22), the first side end portion 21 and the second side end portion 22 (a pair of side end portions 21 and 22) respectively have a non-existing portion and an existing portion. Since the colored portion 3 is provided in a small portion in the side end portion, the ratio of the existing portion is very small compared to the non-existing portion.

In order to join the pair of side end portions 21 and 22 by the electrostatic seal, the lower limit value of the electric resistance value RA of the non-existing portion is set to 1.0×10 ¹⁵ Ω or more as described above. The electrical resistance value RA of the non-existing portion is preferably 5.0×10 ¹⁵ Ω or more, and more preferably 1.0×10 ¹⁶ Ω or more in order to achieve good bonding by sealing.
There is no particular upper limit to the electric resistance value RA of the non-existing portion. When the film base material 2 is formed of a general-purpose material, the upper limit value of the electric resistance value RA of the non-existing portion is, for example, 1.0×10 ²⁰ Ω.

Further, when the electric resistance value RA of the non-existing portion and the electric resistance value RB of the existing portion satisfy the relation of 0<RA/RB≦10, it is possible to effectively prevent the spark from being generated during the electrostatic sealing. The lower limit of RA/RB is preferably 0.01 or more, more preferably 0.1 or more, and further preferably 0.2 or more. The upper limit of RA/RB is preferably 7 or less, and more preferably 5 or less.
The electric resistance value RA of the non-existing portion and the electric resistance value RB of the existing portion are both surface resistance values in the surface direction of the surface of the portion. The electric resistance value can be measured according to JIS K 6911.

The electric resistance value RA of the non-existing portion is determined by the electric resistance value on the surface of the film substrate 2.
For example, when the design print layer or the like is not provided on the pair of side end portions 21 and 22 as described above, since the pair of side end portions 21 and 22 are made of the film base material 2 itself, the electric power of the non-existing portion is reduced. The resistance value RA is determined by the electric resistance value on the surface of either one of the pair of side end portions 21 and 22. Further, when the design printing layer is provided on either or both of the pair of side end portions 21 and 22, the electric resistance value RA of the non-existing portion is the bonding surface (film base) having no design printing layer. It is determined by the electric resistance value at the surface of the material 2 itself).
Therefore, the electric resistance value by using a 1.0 × ^{10 15} Ω or more of the film substrate 2, the electrical resistance value RA can easily configure no sites over 1.0 × ^{10 15} Ω. Such a film base material 2 can be selected from conventionally known heat-shrinkable synthetic resin films, but in order to prevent the electrostatic seal from being hindered, in particular, the film base material 2 which does not substantially contain an antistatic agent. Is preferably used.

Further, the electric resistance value RB of the existing portion is determined by the electric resistance value on the surface of the colored portion 3.
For example, the electric resistance value RB of the existing portion including the laminated portion of the film substrate 2 and the colored portion 3 is determined by the electric resistance value on the surface of the colored portion 3 of the laminated portion. When the colored portion 3 is composed of the colored printing layer as described above, the electrical resistance value RB of the existing portion is determined by the electrical resistance value on the surface of the colored printing layer formed on the film substrate 2.
By forming the desired colored portion 3 in consideration of the electric resistance value of the film base material 2, it is possible to configure the existing portion that satisfies the relationship of 0<RA/RB≦10.

<Example of using overlap film>
The overlap film 1 of the present invention is used by being attached to various articles.
The overlap film 1 is used by being coated and mounted around one article for the purpose of a protective film, or is coated and mounted around a group of a plurality of articles for the purpose of protecting and binding film. Used.
The article is not particularly limited, and examples thereof include instant foods such as instant noodles, dairy products such as yogurt, favorite foods such as jelly and pudding, beverages, seasonings, sanitary products such as shampoo, and fresh foods such as meat. A container that is housed; an item itself such as a dry battery is included.
When the article is a container in which the contents are stored, the outer shape of the container is not particularly limited, and is a cylindrical shape such as a cylindrical shape, an elliptic cylindrical shape, or a rectangular cylindrical shape; , Inverted truncated pyramid shape such as inverted quadrangular pyramid shape; irregular shape such as gourd shape.
The material of the container is not particularly limited, and examples thereof include synthetic resin, foam synthetic resin, metal, glass, pottery, and wood material.

FIG. 6 is a side view schematically showing a packaging machine 9 (so-called horizontal pillow packaging machine 9) for mounting the long strip-shaped overlap film 1 on the article 8.
Referring to FIG. 6, the packaging machine 9 includes a conveying device 91 that conveys the article 8 and the overlap film 1, a forming device (not shown) that forms the overlap film 1 into a tubular shape, and positive and negative electrodes 921. , 922, a thermal fusing cutter 93, a heating device 94, and a mark sensor 96.
The long strip-shaped overlap film 1 wound on a roll is drawn out to a line so that the lateral direction of the overlap film 1 is the circumferential direction, and the overlap film 1 is formed into a tubular shape by a molding device. When forming the tubular shape, the pair of side end portions 21 and 22 are overlapped with each other so that the back surface side of the overlap film 1 faces inside. For example, the back surface of the second side end portion 22 is superposed on the front surface of the first side end portion 21 of the overlap film 1. The article 8 is inserted into the tube of the overlap film 1 formed into a tube at a constant interval by the transfer device 91, and the pair of side end portions 21 and 22 overlapped with each other is used as a positive electrode and a negative electrode. By passing between 921 and 922, the pair of side end portions 21 and 22 are joined by electrostatic sealing. In this case, the front surface of the first side end portion 21 and the back surface of the second side end portion 22 are joint surfaces.

The long overlap film 1 formed in a tubular shape by joining the pair of side end portions 21 and 22 with an electrostatic seal is wrapped with one article 8 while being shorted by the heat fusing cutter 93. Fuse and heat seal along hand direction. Thereby, the pre-wrapping body X in which the periphery of one article 8 is wrapped with the overlap film 1 is obtained, and the pre-wrapping body X is heated by the heating device 94, so that the overlap film 1 is heat-shrinked. And adheres to the article 8. In this way, the overlapping package Y is obtained.
The mark sensor 96 optically detects the colored portion 3, and is arranged at an appropriate position before (on the upstream side of the line) of the thermal fusing cutter 93. In the illustrated example, the mark sensor 96 is arranged in front of (on the upstream side of) the molding apparatus. The colored portion 3 used as a mark by the mark sensor 96 is also called a phototube mark portion.

When the overlap film 1 of the present invention is used, static electricity is generated at the side end portions 21 and 22, and the side end portions 21 and 22 can be satisfactorily joined by electrostatic sealing. Since no sparks are generated in the colored portion 3 (photoelectric tube mark portion) and its vicinity during the electrostatic sealing, the overlapping package Y can be continuously manufactured without interrupting the packaging work.
Further, since no spark is generated during the electrostatic sealing, the overlapping package Y in which the pair of side end portions 21 and 22 are neatly joined by the electrostatic sealing is obtained.
It is presumed that the reason why the overlap film 1 of the present invention does not cause a spark is that the difference between the electric resistance value RA of the non-existing portion and the electric resistance value RB of the existing portion is set to be extremely small. That is, in the longitudinal direction of the side end that passes through the electrode of the electrostatic sealing device, there are alternating portions with and without portions, but due to the small difference in the electrical resistance values of both portions, the flow of static electricity becomes sharp. It is estimated that it will become difficult to change and spark will not occur.

<Overlap package>
As shown in FIGS. 7 to 9, the overlapping package Y of the present invention has an article 8 and an overlap film 12 that wraps the periphery of the article 8.
In the illustrated example, one article 8 is wrapped with the overlap film 12, but as described above, a group of two or more articles 8 may be wrapped with the overlap film 12.
The overlap film 12 attached to the article 8 extends in a direction substantially orthogonal to the joint portion 6 on both sides of the joint portion 6 in which the pair of side end portions 21 and 22 are joined by electrostatic sealing. It has a pair of fusing seal parts 71 and 72. The overlap film 12 is formed in a hermetically sealed bag shape by the joining portion 6 and the fusing seal portions 71 and 72 in a state in which the article 8 is included, and is further adhered to the article 8 by heat shrinkage.

In the joint portion 6, except for the second colored portion 32, the front surface of the first side end portion 21 and the back surface of the second side end portion 22 of the film base material 2 are directly joined by electrostatic sealing. When the first side end portion 21 and the second side end portion 22 are made of the film base material 2 itself, the front and back surfaces of the film base material 2 are directly attached to each other except where the second colored portion 32 is interposed. It is joined by an electrostatic seal.
In addition, in the joint portion 6, the portion where the second colored portion 32 is interposed may not be sufficiently electrostatically sealed, but since the ratio of the colored portion 3 to the side end portion is very small, The pair of side end portions 21, 22 forming the joint portion 6 will not be inadvertently peeled off.

It is also possible to join the pair of side end portions 21 and 22 so that the colored portion 3 (photoelectric tube mark portion) does not intervene on the joint surface (the surface where the side end portion 21 and the side end portion 22 overlap each other). ..
For example, as described above, in the overlap film in which the colored portion 3 (first colored portion 31) is provided on the side end portion 21 and the colored portion is not provided on the side end portion 22, the colored portion 3 is formed on the joint surface. Will no longer intervene.

Further, although the overlapping film is used as the photoelectric tube mark portion for detecting the colored portion 3 by the mark sensor, the usage of the colored portion 3 is not limited to the photoelectric tube mark portion.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited to the following examples.

[Materials used]
-Heat-shrinkable film A polypropylene film having a thickness of 15 μm. Product name "Kojin Polyset FDA" manufactured by Kojin Film & Chemicals Co., Ltd. This polypropylene film is a film containing no antistatic agent in its components.
This polypropylene film was a biaxially stretched heat-shrinkable film, and had a heat shrinkage in the MD direction of about 16% and a heat shrinkage in the TD direction of about 20%. This heat shrinkage rate is a value measured at 100° C. according to JIS Z 1709. The polypropylene film was a long strip film having the MD direction as the longitudinal direction, and the length in the TD direction (short direction) was 280 mm.

・Ink (A)
Product name “DIC UNITAF 407B Medium Yellow A-11” manufactured by DIC Corporation
・Ink (B)
Product name "DIC UNITAF 105 Beni A-11" manufactured by DIC Corporation
・Ink (C)
Product name “UNITAF 507 primary color indigo A-21” manufactured by DIC Corporation
・Ink (D)
Product name of DIC Corporation "DIC XOP-1385 (revised) 407B middle yellow"
・Ink (E)
Product name of DIC Corporation "DIC XOP-1385 (revised) 105 Beni"
・Ink (F)
Product name of DIC Corporation “DIC XOP-1385 (revised) 507 primary color indigo SP2”
・Ink (G)
Product name of DIC Corporation "DIC UNITAF 805 black ink A-30"
・Ink (H)
Product name of DIC Corporation "DIC XOP-1385 (revised) 805 black ink A-11"
The inks (A) to (F) contained no carbon black and contained organic pigments expressing each color, and the inks (G) and (H) contained carbon black. From the viewpoint of color, the inks (A) and (D) are yellow, the inks (B) and (E) are magenta, and the inks (C) and (F) are cyan. And the inks (G) and (H) were black.
The inks (A) to (H) were adjusted inks whose viscosity and the like were adjusted by a known general-purpose method to the extent that gravure printing was possible.

[Measurement of electrical resistance]
-Measurement of electric resistance value of non-existing portion (heat-shrinkable film) To examine electric resistance value RA of the non-existing portion, electric resistance value of the heat-shrinkable film was measured.
That is, a heat-shrinkable film (polypropylene film) was cut into a square of length×width=100 mm×100 mm to prepare a sample for measurement of a non-existing portion. The surface resistance value of this measurement sample was measured according to JIS K6911.
As a measuring instrument, a digital ultra-high resistance measuring instrument (trade name “R8340” manufactured by ADC Co., Ltd.) was used. An outline of the sample mounting portion of this measuring instrument is shown in FIGS. 10(a) to 10(c). As shown in FIG. 10( a ), the sample attachment site attached to the measuring instrument is a pedestal, a support plate fixed on the pedestal, and a pair of electrode portions provided so as to be able to come into contact with and separate from the support plate. And. FIG. 3B is a plan view of the support plate as seen from above. The support plate has a circular shape in plan view with a diameter of 100 mm and is made of an insulating material. FIG. 6C is a plan view of the pair of electrodes as seen from below. The electrode is composed of one electrode having a circular shape in plan view with a diameter of 50 mm and the other electrode having a ring shape in plan view with an outer diameter of 80 mm and an inner diameter of 70 mm, and the other electrode is arranged so as to surround the outside of one electrode. Has been done. The thick line is an electric wire that connects the electrode and the measuring device.

As shown in FIG. 3D, the measurement sample is placed on the support plate, the pair of electrodes is moved to the support plate side, and as shown in FIG. 2E, between the support plate and the pair of electrodes. The sample was clamped in. In that state, a DC voltage of 500 V was applied from the electrodes in an environment of 29° C., 1 atm, and relative humidity of 30%, and the electric resistance value of the surface of the sample was measured. As a result, the electric resistance value RA of the non-existing portion was 1.5×10 ¹⁶ Ω.

-Measurement of electric resistance value of existing portion (colored portion) To examine the electric resistance value RB of the existing portion, a print layer was formed on the heat-shrinkable film, and the electric resistance value of the print layer was measured.
That is, the ink (A) is solidly printed on one surface of the heat-shrinkable film (polypropylene film) by using a simple gravure printing machine, so that the ink (A) is formed on only one surface of the heat-shrinkable film. A printed layer having a thickness of about 0.5 μm was formed.
The printed layer/heat-shrinkable film was cut into a rectangle of length×width=100 mm×100 mm to prepare a measurement sample for the existing portion.
Similar to the measurement sample of the non-existing portion, the measurement sample was set on the sample mounting portion shown in FIG. 10, and the electric resistance value was measured using a digital ultrahigh resistance measuring instrument. As shown in FIG. 10(f), the measurement sample was placed so that the printed layer was on the side of the pair of electrodes, and the electric resistance value of the surface of the printed layer was measured. The results are shown in Table 1 as the electric resistance value RB (Ω).
With respect to the inks (B) to (H), a printing layer was formed in the same manner as the ink (A), and the electric resistance value of each was measured. Table 1 shows the electric resistance value RB (Ω) of each existing portion.

[Example 1]
By partially printing the ink (A) on the back surfaces of the pair of side end portions of the heat-shrinkable film (polypropylene film) using a simple gravure printing machine, the thickness of the ink (A) of about 0.5 μm can be obtained. A printed layer (photoelectric tube mark portion which is a colored portion) was formed. This print layer has a rectangular shape of length×width=5 mm×10 mm in plan view, and was formed including the side edges of the side end portions. The printing layer was formed intermittently in the longitudinal direction of the heat-shrinkable film with a space of 210 mm in the longitudinal direction of the heat-shrinkable film.
Thus, the overlap film of Example 1 as shown in FIG. 11 was produced.

[Examples 2 to 6 and Comparative Examples 1 and 2]
Example 2 was repeated in the same manner as in Example 1 except that the ink (A) of Example 1 was changed to inks (B) to (H) as shown in Table 1 to form a printing layer. 6 to 6 and Comparative Examples 1 and 2 were prepared.

[Wearing test]
An existing packaging machine equipped with an electrostatic sealing device having positive and negative electrodes was loaded with the overlap film of each of the examples and comparative examples, and a pair of side edges of the overlapping film passed between the electrodes of the electrostatic sealing device. As described above, the overlapping package was continuously produced by wrapping the article (collective pack of three yogurt-contained containers) while joining the pair of side end portions (set width of the joint portion is 10 mm). ..
During this packaging operation, the vicinity of the electrode was observed, and whether or not sparks were generated in the printed layer (colored portion) or in the vicinity thereof when the side end portion passed through the electrode was observed. The results are shown in Table 1.
In addition, the state of the electrostatic seal (the state of the joint portion) of the produced overlap package was confirmed. The results are shown in Table 1.
In the column of the state of the joint portion in Table 1, "○" indicates that there was no peeled portion and the side end portion was entirely joined by electrostatic sealing, and "x" indicates the side end portion. Small holes were made in some places, indicating that the side ends were not entirely well joined.

As is clear from Table 1, in the overlap films of Examples 1 to 6 satisfying 0<RA/RB≦10, no spark was observed during electrostatic sealing. On the other hand, in the overlap films of Comparative Examples 1 and 2 in which RA/RB exceeded 1.0×10 ¹⁰ , sparks were observed during electrostatic sealing.

1,11,12 Overlap film 2 Film substrate 21 Side end (first side end)
22 side end (second side end)
3, 31, 32 Colored part 4 Design printing layer 6 Joined part joined by electrostatic seal 8 Article Y Overlap package

Claims (5)

An overcoat having a long strip-shaped film base material having a pair of side end portions that can be joined by electrostatic sealing, and a colored portion provided at a part of at least one side end portion of the pair of side end portions. In wrap film,
The electric resistance value RA of the side end portion having no colored portion is 1.0×10 ¹⁵ Ω or more,
The overlap film in which the electric resistance value RA of the portion having no colored portion and the electric resistance value RB of the portion having the colored portion in the side end portion satisfy the relationship of 0<RA/RB≦10. .. The overlap film according to claim 1, wherein the pair of side end portions of the film base material are directly joined by an electrostatic seal. The pair of side end portions is composed of only a colorless and transparent film base material, and the colored portion is composed of a colored print layer other than black printed on the side end portion. The described overlap film. The overlap film according to any one of claims 1 to 3, wherein the colored portion is substantially free of carbon black. An article, an overlap film having a film base material and a colored portion provided on a part of at least one side end portion of the pair of side end portions of the film base material, wherein the pair of side end portions is static. An overlap film joined by an electric seal, and an overlap package in which the article is packaged in the overlap film,
The electric resistance value RA of the side end portion having no colored portion is 1.0×10 ¹⁵ Ω or more,
The overlapped package in which the electric resistance value RA of the portion having no colored portion and the electric resistance value RB of the portion having the colored portion of the side end portion satisfy the relationship of 0<RA/RB≦10. ..

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