Adhesive film

Abstract

To provide an adhesive film configured to inhibit occurrence of a curl.SOLUTION: An adhesive film includes an OPP film 10, an anchor layer 30 composed mainly of chlorinated polypropylene, and a rubber-based hot melt adhesive layer 20 in this order.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an adhesive film.

Background Art

[0002] Conventionally, there has been a covering member called a so-called overlay paper that covers the upper surface of foods, fruits, etc. contained in trays or containers. In the past, paper was literally used as the overlay paper, but when plastic films became commonly distributed, plastic films came to be used as the overlay paper.

[0003] In recent years, at the outer edge of a rectangular plastic film, an adhesive is applied to portions of a pair of parallel sides, and the overlay paper is fixed to the tray or container in a short time by attaching the overlay paper to the tray or container with this adhesive.

[0004] A plastic film with a similar structure is disclosed in Patent Document 1. Patent Document 1 is an invention of a cover tape used for an electronic component package, and is a tape for sealing the pocket of a carrier tape with a pocket in which electronic components are stored. This cover tape has a structure in which a primer layer is provided on a long polymer film, an electrostatic control layer in which carbon nanotubes are dispersed in a dielectric polymer binder is provided thereon, and adhesive strips are provided on both long edges thereof. In the examples, OPP is used for the polymer film, polyurethane is used for the primer layer, and a rubber-based hot melt pressure-sensitive adhesive is used. The primer layer is provided to adhere the electrostatic control layer.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The cover tape disclosed in Patent Document 1 is provided with an electrostatic control layer to prevent electrostatic discharge to electronic components. However, when used as a sticker for foods, fruits, etc., the electrostatic control layer is unnecessary, and if the electrostatic control layer is not provided, the primer layer is also unnecessary. That is, for stickers for foods, fruits, etc., it is only necessary to directly apply an adhesive to the plastic film.

[0007] However, when a rubber-based hot melt adhesive is applied to an OPP film, the OPP film curls, and in a dispenser, which is a machine for laminating to a tray, a problem occurs in that chucking failure occurs.

[0008] The present invention has been made in view of such points, and an object thereof is to provide an adhesive film that suppresses curling.

Means for Solving the Problems

[0009] In order to solve the above problems, the adhesive film of the present invention is characterized by having an OPP film, an anchor layer mainly composed of chlorinated polypropylene, and a rubber-based hot melt adhesive layer in this order.

[0010] The OPP film may have a release agent layer on the surface opposite to the surface facing the anchor layer.

[0011] The coating amount of the anchor layer may be 0.15 g / m 2 or more and 3.00 g / m 2 or less.

[0012] The anchor layer may contain a lubricant.

Effects of the Invention

[0013] An anchor layer mainly composed of chlorinated polypropylene is provided on the OPP film, and a rubber-based hot melt adhesive layer is provided on the anchor layer, so that the anchor layer can prevent the OPP film from curling.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following description of the preferred embodiments is merely illustrative in nature and is not intended to limit the present invention, its applications, or its uses.

[0016] (Embodiment 1) A schematic cross-sectional view of the adhesive film according to Embodiment 1 is shown in FIG. 1. The adhesive film 100 according to Embodiment 1 has a configuration in which anchor layers 30 are provided at both outer edge portions on one surface of the OPP film 10, and a rubber-based hot melt adhesive layer 20 is provided on the opposite side of the OPP film 10 from the anchor layers 30. The anchor layers 30 and the rubber-based hot melt adhesive layer 20 are provided so as to extend in a strip shape perpendicular to the cross-section shown in FIG. 1.

[0017] The OPP film 10 has a thickness of 25 μm. The anchor layer 30 contains more than 50% of chlorinated polypropylene and is mainly composed of chlorinated polypropylene.

[0018] The rubber-based hot melt adhesive layer 20 is composed of a rubber-based hot melt adhesive using a synthetic rubber having a styrene-based copolymer such as SIS (styrene-isoprene-styrene copolymer), SBS (styrene-butadiene-styrene copolymer), SEPS (styrene-ethylene-propylene-styrene copolymer), SEBS (styrene-ethylene-butylene-styrene copolymer), and hydrogenated products thereof as a base polymer.

[0019] Figure 2 is a schematic cross-sectional view of the adhesive film 900 according to the conventional example. Compared with the adhesive film 100 according to the present embodiment, the adhesive film 900 according to the conventional example directly provides the rubber-based hot melt adhesive layer 20 on the OPP film 10 without an anchor layer.

[0020] When the adhesive film 900 according to the conventional example is provided with the rubber-based hot melt adhesive layer 20 and left at room temperature, a phenomenon occurs in which the portion of the OPP film 10 provided with the rubber-based hot melt adhesive layer 20 curls to the side opposite to the surface provided with the rubber-based hot melt adhesive layer 20. This curl exceeds 90 degrees during the 7-day standing, and in a dispenser, which is a machine for laminating on a tray, problems such as the inability to perform chucking (the operation of gripping the OPP film) or the inability to grip the normal part occur.

[0021] The inventor of the present application presumed that the low molecular components of the additives (such as mineral oil) of the rubber-based hot melt adhesive and the components that soften the OPP film were the causes of curling, and considered countermeasures. As a countermeasure, an anchor layer was provided to prevent the low molecular components and softening components considered to be the causes of curling from migrating from the rubber-based hot melt adhesive to the OPP film, and trial and error was carried out to search for suitable anchor agents.

[0022] As materials (resins) for coating as the anchor layer, polyester, polyethyleneimine, copolymer acrylic polymer, polyurethane, a mixture of polyurethane and vinyl chloride acetate, polyolefin, modified polyolefin, chlorinated polypropylene, etc. were tried. The coating amount was 0.5 to 1.0 g / m 2 each. After forming the anchor layer, a rubber-based hot melt adhesive layer 20 was provided thereon to examine whether curling occurred. As a comparative example, a sample without an anchor layer was also prepared, and a rubber-based hot melt adhesive layer was provided for examination. Five types of chlorinated polypropylene and 13 types of other resins were examined.

[0023] The examination was carried out by preparing each sample with a 6 mm width from the end of the OPP film as an uncoated part and providing an anchor layer and a rubber-based hot melt adhesive layer in this order with a 15 mm width. The anchor layer was formed slightly wider than the rubber-based hot melt adhesive layer, and the rubber-based hot melt adhesive layer had a thickness of 30 μm. The samples were left for 1 day under aging conditions of 40°C and then left at room temperature for 7 days, and the amount of curling was measured respectively. The anchor layer was formed by coating a solution of the resin dissolved in a solvent by a known method and then vaporizing the solvent. Since the rubber-based hot melt adhesive is in a solid state (in some cases, a very viscous liquid) at room temperature, the rubber-based hot melt adhesive was heated and melted by a heating and melting facility called an applicator, and the adhesive in a state of appropriate viscosity was supplied to various coating machines and coated on the release paper, and then transferred onto the anchor layer to form it.

[0024] As a result, in the case of an anchor layer mainly composed of chlorinated polypropylene, curling was 5 mm or less both after being left for 1 day under aging conditions of 40°C and after being left at room temperature for 7 days thereafter, and no chucking failure occurred in the dispenser. However, in the comparative example without an anchor layer and in resins other than chlorinated polypropylene, curling exceeded 5 mm under either condition, and it was found that in many resins, the OPP film curled by 90° or more.

[0025] Note that "using chlorinated polypropylene as the main component" means that the content of chlorinated polypropylene as a solid content is more than 50% by mass. Among the five types of chlorinated polypropylene examined this time, when the anchor layer was prepared, the content of chlorinated polypropylene was 90% by mass or more in all cases. If the degree of chlorination of chlorinated polypropylene is too low, it becomes difficult to dissolve in the solvent and coating becomes difficult. If the degree of chlorination is too high, the adhesion to the OPP film becomes low. Therefore, the chlorinated polypropylene used for the anchor layer preferably has a chlorine content of 25% by mass or more and 42% by mass or less. In addition, since a higher molecular weight of chlorinated polypropylene has a higher function of preventing the migration of low molecular components and softening components to the OPP film, a higher molecular weight is preferred. For example, the molecular weight of chlorinated polypropylene is preferably 5000 or more, and more preferably 10000 or more.

[0026] In addition, when examining the relationship between the coating amount of chlorinated polypropylene and the amount of curl, it was found that when the coating amount is 0.15 g / m 2 or more, the amount of curl can be such that there is substantially no problem with chucking in the dispenser. The effect of suppressing curl does not improve proportionally to the coating amount even if the coating amount is increased, and increasing the coating amount will increase the manufacturing cost. Therefore, the coating amount is preferably 0.15 g / m 2 or more and 3.00 g / m 2 or less, and more preferably 0.2 g / m 2 or more and 2.00 g / m 2 or less.

[0027] Depending on the type and coating amount of chlorinated polypropylene, there may be a lack of slipperiness in the process after applying the anchor layer 20. In such a case, a lubricant such as a wax component may be added to the anchor layer 20. For example, a method of adding 1 to 10% by mass of a wax component to a coating solution in which chlorinated polypropylene is dissolved in a solvent may be used.

[0028] The pressure-sensitive adhesive film of this embodiment coats chlorinated polypropylene on the OPP film as an anchor layer, and forms a rubber-based hot melt pressure-sensitive adhesive layer thereon. Therefore, the chlorinated polypropylene prevents the transfer of substances that cause curling from the rubber-based hot melt pressure-sensitive adhesive layer to the OPP film, and it is possible to prevent the pressure-sensitive adhesive film from curling.

[0029] (Embodiment 2) The pressure-sensitive adhesive film according to Embodiment 2 is different from the pressure-sensitive adhesive film according to Embodiment 1 in that it has a release agent layer on the surface opposite to the surface facing the anchor layer of the OPP film.

[0030] The pressure-sensitive adhesive film 110 according to Embodiment 2 shown in FIG. 3 is provided with a release agent layer 40 on the surface opposite to the surface facing the anchor layer 30 of the OPP film 10 of the pressure-sensitive adhesive film 100 according to Embodiment 1. And a primer layer 50 for improving the adhesion between the two is provided between the release agent layer 40 and the OPP film 10. Further, the release agent layer 40 is formed in a strip shape extending perpendicular to the cross section shown in FIG. 3 at a position facing the rubber-based hot melt pressure-sensitive adhesive layer 20 with the OPP film 10 interposed therebetween, and the width of the strip is set to be larger than the width of the rubber-based hot melt pressure-sensitive adhesive layer 20.

[0031] In the pressure-sensitive adhesive film 110 of this embodiment, since the release agent layer 40 is formed on the surface opposite to the rubber-based hot melt pressure-sensitive adhesive layer 20 with respect to the OPP film 10, when the long pressure-sensitive adhesive film 110 extending perpendicular to the cross section shown in FIG. 3 is wound up into a roll shape, the rubber-based hot melt pressure-sensitive adhesive layer 20 will come into contact with the release agent layer 40, and it is possible to prevent the rubber-based hot melt pressure-sensitive adhesive layer 20 from adhering to the OPP film 10. When using this roll as a sticker paper, since the rubber-based hot melt pressure-sensitive adhesive layer 20 can be easily released from the release agent layer 40 and cut into single sheets, it can be supplied as a long pressure-sensitive adhesive film roll.

[0032] (Other Embodiments) The above embodiments are examples of the invention of the present application, and the invention of the present application is not limited to these examples. Well-known techniques, conventional techniques, or known techniques may be combined with or partially replaced in these examples. Further, modified inventions that can be easily conceived by those skilled in the art are also included in the invention of the present application.

[0033] The thickness of the OPP film and the coating thickness of the rubber-based hot melt adhesive layer are not limited to the thicknesses of the above embodiments.

[0034] In addition to coating the release paper and then transferring it, the rubber-based hot melt adhesive layer may be directly coated and formed on the anchor layer on the OPP film from a coater.

Explanation of Reference Numerals

[0035] 10 OPP film 20 Rubber-based hot melt adhesive layer 30 Anchor layer 40 Release agent layer 100 Adhesive film 110 Adhesive film

Claims

1. An adhesive film having, in this order, an OPP film, an anchor layer mainly composed of chlorinated polypropylene, and a rubber-based hot melt adhesive layer.

2. The adhesive film according to claim 1, having a release agent layer on a surface opposite to the surface of the OPP film facing the anchor layer.

3. The coating amount of the anchor layer is 0.15 g / m 2 or more and 3.00 g / m 2 or less. The pressure-sensitive adhesive film according to claim 1 or 2.

4. The adhesive film according to claim 1 or 2, wherein the anchor layer contains a lubricant.

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