JP2005313953A - Multi-layered sheet having peel detection function and resealable function - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multi-layered sheet which has the peel detection function capable of detecting and determining whether or not an article is resealed after a third party tamper-unseals the article while the article is delivered or displayed over the counter, has adequate easily unsealable strength, and has a resealable function with a peel detection function capable of maintaining excellent resealability even when repeatedly performing the resealing. <P>SOLUTION: The multi-layered sheet with the peel detection function and the resealable function has a pressure-sensitive adhesive resin layer (A) and a heat-seal resin layer (B) in contact therewith. The heat-seal resin layer (B) and a heat-sealable body are heat-sealed to each other. When a part of the multi-layered sheet is peeled from the heat-sealable body, at least the heat-seal resin layer (B) is broken at a boundary between the heat-seal part and a non-heat-seal part, and the pressure-sensitive adhesive resin layer (A) is interface-peeled from an adjacent layer over the entire area of the heat seal part, or the pressure-sensitive adhesive resin layer (A) is peeled through cohesion failure within the layer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a multilayer sheet having a peel detection function and a reseal function capable of detecting that an unsealed portion has good adhesiveness when it is opened, repeatedly maintains a re-sealing strength, and can be opened.

  A conventional multilayer film that can be resealed is a flexible packaging material comprising a base layer, a pressure-sensitive adhesive layer adjacent to the base layer, and a skin layer covering the pressure-sensitive adhesive layer. Each surface has a coefficient of friction that allows the material to be machined in the packaging machine, which material is sealed to itself by the sealing jaws of the packaging machine and remains closed during normal handling For initial opening, a package with a seal that can be easily separated by hand can be formed. Flexible packaging material that is exposed at the surface of the sealing area so that the packaging material can be sealed against itself in the area of the sealing by the application of hand pressure only to reclose the package Known (e.g., see Patent Document 1.).

  Furthermore, as a multilayer film that can be resealed, hydrogenation of a surface resin layer (A) containing a thermoplastic resin (a) and a rubbery block copolymer containing a styrene block and a diene block The adhesive resin layer (B) containing the product (b1) and the tackifier (b2), and the heat seal resin layer (C) containing the thermoplastic resin (c) are (A) / (B) / (C) is a multilayer film laminated in the order of heat sealing the heat seal resin layer (C) and the heat seal resin layer (C) and a heat sealable thermoplastic resin layer. Then, when peeled off, the heat seal resin layer (C) and the adhesive resin layer (B) are broken and the interface between the adhesive resin layer (B) and the surface resin layer (A) is peeled off, and the adhesive resin layer ( B) Viscosity that can be resealed in the heat seal area Multilayer film exposed in the state is also known (e.g., see Patent Document 2.). Also known is a multilayer film in which the interface between the heat seal resin layer (C) and the adhesive resin layer (B) is peeled off and the adhesive resin layer (B) is exposed in an adhesive state that can be resealed at the heat seal portion. (For example, refer to Patent Document 3). And related techniques thereof are known (for example, see Patent Documents 4 and 5).

  Examples of the resin for the adhesive adhesive layer of the flexible packaging material described in Patent Document 1 include elastomers such as styrene / butadiene copolymers, styrene / isoprene copolymers, ethylene / vinyl acetate copolymers, and adhesives such as terpene resins and petroleum hydrocarbon resins. A pressure sensitive adhesive which is a mixture of an imparting agent is exemplified, and examples of the resin for the adhesive resin layer of the multilayer film described in Patent Document 2 include a hydrogenated styrene-butadiene block copolymer (SB), styrene A hydrogenated rubber block copolymer such as a hydrogenated butadiene-styrene block copolymer (SBS), a hydrogenated styrene-isoprene-styrene block copolymer (SIS), a rosin resin, A mixture of a terpene resin and a petroleum resin tackifier is illustrated.

  The packaging body using these multilayer films as a lid or bag has a resealing function, so that a third party may perform mischief such as mixing of foreign substances after opening when delivering goods or displaying the store, and reseal, There were concerns about re-shipping and re-displaying. Therefore, it is desired to provide a sheet having a peeling detection function and a resealing function, which is found to be opened once, has an appropriate easy opening strength with a further function, and can maintain a good resealability. It was.

  As such a technique, on one side of a transparent or semi-transparent substrate film, an adhesive layer having an opening display function at a portion corresponding to a sealing portion of a packaging container and capable of being resealed is provided. A packaging container sheet is disclosed (for example, see Patent Document 6). However, in the method specifically shown in the prior art document, an unsealed display portion serving as an opening proof remains on the container side, and the unsealed display portion is a portion having no adhesiveness. Therefore, when resealing is attempted by the method disclosed in the art, it is difficult to obtain the initial adhesive force. In particular, when the area of the opening display portion is increased, the tendency is remarkable, and it is difficult to form a large area opening display. In addition, there is a problem in that the peeled portion must be accurately superimposed on the original position at the time of resealing. If they are overlapped in a shifted state, the unsealed display part will overlap the adhesive layer. Since the unsealed display portion has a relatively low strength and uses a brittle ink material, when the pressure-sensitive adhesive layers overlap, the portion is lost and adheres to the surface of the pressure-sensitive adhesive layer. When this is repeated, the area of the effective adhesive surface of the pressure-sensitive adhesive layer is eventually reduced, and the resealing force is lost. That is, when re-sealing is performed repeatedly, there is a problem that the reseal strength is significantly reduced.

  Furthermore, for example, when the packaging container sheet shown in the art is used as a lid when enclosing a liquid in a cup-shaped container, and the periphery of the opening of the container is adhered with an adhesive layer In general, the adhesive strength of pressure-sensitive adhesives varies greatly with changes in temperature, and the adhesive strength is significantly reduced during low-speed peeling. The internal pressure of enclosed containers such as in summer warehouses and delivery vehicles adheres over a long period of time. If such a state is applied to the part, troubles such as the natural peeling of the bonded part are likely to occur, and there is a problem that reliability for preventing leakage of liquid inside the container is poor. In addition, even when a heat seal layer is used and heat seal bonding is performed, a slitting process is required so that the heat seal layer does not remain in the opening when the multilayer sheet is peeled off, which complicates the processing process. After all, in the adhesion part of the pressure-sensitive adhesive layer and the heat seal layer, it was poor in reliability that could completely prevent liquid leakage.

Japanese National Publication No. 04-502588 (page 2-3) JP2003-175567 (page 4-7) JP 2004-58568 A JP 2004-75181 A JP 2004-83094 A Japanese Patent Laid-Open No. 10-120016 (FIGS. 1-7)

  The object of the present invention is to provide a peeling detection function that can detect and discriminate whether a third party has tampered with the product after opening it at the time of goods delivery or store display and then resealed or unopened, and is reliable. A multilayer sheet having a peel detection function and a reseal function that has a high initial seal strength, an appropriate easy-open strength, and can maintain good resealability even after repeated reseal It is to be.

As a result of intensive studies, the present inventors have completed the present invention. That is, the present invention
A multilayer sheet having both a peel detection function and a reseal function,
A pressure-sensitive adhesive resin layer (A) and a heat seal resin layer (B) in contact therewith,
When heat-sealing the heat-sealable resin layer (B) and the heat-sealable adherend, and then peeling a part of the multilayer sheet from the adherend,
At least the heat seal resin layer (B) breaks at the boundary between the heat seal portion and the non-heat seal portion,
The pressure-sensitive adhesive resin layer (A) peels off from the adjacent layer, or the pressure-sensitive adhesive resin layer (A) peels off due to cohesive failure within the heat seal portion. The present invention provides a multilayer sheet having a peeling detection function and a resealing function.

  The multilayer sheet of the present invention not only has a peeling detection function that can detect and discriminate whether it is unopened, but also has a highly reliable initial seal strength, an appropriate open strength, and repeated re-sealing. Even when stopping, good resealability can be maintained. Therefore, the multilayer sheet of the present invention can be suitably used as a lid material or a bag for a resealable container.

(Structure of multilayer sheet)
FIG. 1 shows a basic structure of a multilayer sheet having a peeling detection function and a resealing function of the present invention (hereinafter referred to as the multilayer sheet of the present invention). The multilayer sheet in FIG. 1 heat-seals the heat-seal resin layer (B) and the heat-sealable adherend, and then peels at least the heat-seal when part of the multilayer sheet is peeled off from the adherend. Whether the resin layer (B) breaks at the boundary between the heat-sealed portion and the non-heat-sealed portion, interferes with the entire heat-sealed portion, and the pressure-sensitive adhesive resin layer (A) peels off from the adjacent layer. Or, the pressure-sensitive adhesive resin layer (A) and the heat seal resin layer (B) are laminated so that the pressure-sensitive adhesive resin layer (A) is peeled by cohesive failure in the layer, A release layer (D) that forms a release indication (d) (not shown) when the heat-seal resin layer (B) is heat-sealed and peeled off, and transparent or translucent. Film-like base material layer support (C) is sequentially stacked. And it has a structure.

  In addition, the material of the adherend using the multilayer sheet of the present invention can be bonded by heating the heat seal resin layer (B), that is, the heat seal resin layer (B) can be heat sealed. The material is not particularly limited as long as it is a simple material. Examples of such materials include glass, metal, resin, paper, and the like, and a resin containing a polyethylene resin, a polypropylene resin, a polyester resin, or a polystyrene resin is preferable. Especially, it is more preferable that it is resin of the same kind as resin used for a heat seal resin layer (B).

  When the multilayer sheet of the present invention is heat-sealed to an adherend and peeled off, at least the heat-seal resin layer (B) is broken and the pressure-sensitive adhesive resin layer (A) is re-applied to the heat-seal portion. Since the structure is exposed in a sealable state, for example, when the liquid is sealed in a cup-shaped container, the opening part of the container is heat sealed at the periphery of the opening of the container and peeled off. Since the multilayer sheet is not heat sealed, the heat seal resin layer remains on the multilayer sheet side, and the liquid sealed in the container can be taken out from the opening. On the other hand, after the liquid is sealed in the container and before the multilayer sheet is peeled off, there is no need for a cutting process or the like in the heat seal layer, so there is no need for complicated secondary processing steps, and seamless heat Since it is sealed with the sealing layer, the initial sealing reliability (sealing strength) is high, and further, the adhesive strength between the heat sealing portion and the heat sealing portion of the adherend need not be peeled at this interface, This is excellent in that it can be sufficiently increased to prevent leakage and the sealing reliability can be further improved.

Although the basic structure of the multilayer sheet of the present invention is FIG. 1, a more preferred embodiment is shown in FIG. The multilayer sheet of FIG. 2 heat-seals the heat-seal resin layer (B) and the heat-sealable adherend, and then peels at least the heat-seal when part of the multilayer sheet is peeled from the adherend. Whether the resin layer (B) breaks at the boundary between the heat-sealed portion and the non-heat-sealed portion, interferes with the entire heat-sealed portion, and the pressure-sensitive adhesive resin layer (A) peels off from the adjacent layer. Or the thermoplastic resin layer (X), the pressure sensitive adhesive resin layer (A), and the heat seal resin layer (B) so that the pressure sensitive adhesive resin layer (A) is peeled off by cohesive failure in the layer. ) Are laminated in the order of (X) / (A) / (B), and a multilayer structure part (II) having a resealing function, and when peeled off by heat sealing with the adherend, d) The release layer (D) (not shown) is formed on the back side A multilayer structure portion (I) having a peeling detection function comprising a transparent or translucent film-like base material layer support (C) formed on the release layer (D) of the multilayer structure portion (I). Including the thermoplastic resin layer (X) of the multilayer structure portion (II) so as to cover the whole or part of the back surface side of the substrate layer support (C).

  A more preferred embodiment is shown in FIG. In the multilayer sheet of FIG. 3, the base material layer support (D) is provided so that the colored layer (E) covers the release layer (D) so that the release indication (d) (not shown) is displayed more clearly. C) the surface of the colored layer (E) of the multilayer structure part (I) having a peeling detection function laminated on the whole surface or a part thereof, the thermoplastic resin layer (X) and the pressure-sensitive adhesive resin layer (A) The heat seal resin layer (B) is laminated in the order of (X) / (A) / (B) and the thermoplastic resin layer (X) surface side of the multilayer structure part (II) having a reseal function is laminated. And are united.

  A further preferred embodiment is shown in FIG. The multilayer sheet of FIG. 4 includes the surface of the colored layer (E) of the multilayer structure part (I) having the peeling detection function of FIG. 3 and the thermoplastic resin of the multilayer structure part (II) having the reseal function of FIG. A reinforcing layer (G) is provided between the surface of the layer (X) and the adhesive layer (F) on one surface, and the other surface to ensure the display of the peeling display (d) (not shown). Are laminated so as to adhere to each other via an adhesive layer (F ′).

  5 shows that when a part of the multilayer sheet of FIG. 3 is peeled off from the adherend, peeling occurs between the colored layer (E) and the peeling layer (D), and a peeling indication (d) appears. FIG. In addition, h in a figure shows a heat seal part, FIG. 5 shows the case where the pressure-sensitive adhesive resin layer (A) and the heat seal resin layer (B) are broken at the boundary between the heat seal part and the non-heat seal part. An example is shown. Furthermore, when the pressure-sensitive adhesive resin layer (A) and the thermoplastic resin layer (X) of the heat-sealed portion are peeled off at the interface, the pressure-sensitive adhesive resin layer (A) having an adhesive surface is exposed. An example of a state where resealing is possible is also shown. When the pressure-sensitive adhesive resin layer (A) and the thermoplastic resin layer (X) that have undergone interfacial separation at the heat seal portion are brought into contact again, the openings of the container, the bag, and the like are sealed.

  FIG. 6 shows that when a part of the multilayer sheet of FIG. 3 is peeled off from the adherend, peeling occurs between the base material layer support (C) and the peeling layer (D), and a peeling indication (d) appears. FIG. In addition, like FIG. 5, h in a figure shows a heat seal part and a pressure-sensitive-adhesive resin layer (A) and a heat seal resin layer (B) fracture | rupture in the boundary of a heat seal part and a non-heat seal part. An example in which the surface of the pressure-sensitive adhesive resin layer (A) is exposed and resealable is shown.

(Outline of multi-layer structure (II))
First, the multilayer structure part (II) will be described in detail.
In the multilayer structure part (II), the thermoplastic resin layer (X), the pressure-sensitive adhesive resin layer (A), and the heat seal resin layer (B) are laminated in the order of (X) / (A) / (B). When the heat-seal resin layer (B) is heat-sealed from an adherend that can be heat-sealed and peeled off, at least the heat-seal resin layer (B) is not in contact with the heat-seal portion. Any multilayer film may be used as long as it breaks at the boundary of the heat-sealed portion and the pressure-sensitive adhesive resin layer (A) is exposed in a re-sealable state over the entire surface of the heat-sealed region. There is no particular limitation on the mechanism in which the pressure-sensitive adhesive resin layer (A) is exposed in an adhesive state that can be resealed on the surface of the heat seal region, the manufacturing method of the multilayer film, etc. Among them, as the multilayer structure part (II), A coextruded multilayer film obtained by a coextrusion method is preferred.

As such a multilayer film, for example, when the heat seal resin layer (B) is partially heat sealed with an adherend that can be heat sealed, and then peeled off,
・ The heat-seal resin layer (B) breaks at the boundary between the heat-seal part and the non-heat-seal part, and cohesively breaks in the pressure-sensitive adhesive resin layer (A), peels off, and can be resealed on the surface of the heat-seal area Multilayer film (α) that is exposed in an adhesive state,
-The heat-seal resin layer (B) breaks at the boundary between the heat-seal part and the non-heat-seal part, and the interface between the pressure-sensitive adhesive resin layer (A) and the heat-seal resin layer (B) peels off, resulting in pressure-sensitive adhesion Multilayer film (β) in which the adhesive resin layer (A) is exposed in a re-sealable adhesive state on the surface of the heat seal region,
・ The pressure-sensitive adhesive resin layer (A) and the heat-seal resin layer (B) break at the boundary between the heat-seal part and the non-heat-seal part, and the thermoplastic resin layer (X) and the pressure-sensitive adhesive resin layer (A) Is peeled off, and the pressure-sensitive adhesive resin layer (A) is exposed in an adhesive state that can be resealed on the surface of the heat seal region (γ) (peeling pattern in FIGS. 5 and 6),
Etc. Among these multilayer films (α), (β), (γ), there is little roughness on the peeled surface, and the adhesive strength at the time of resealing is strong and stable. γ) is preferred. Among these, a multilayer film (γ) is particularly preferable.

(Thermoplastic resin layer (X))
The thermoplastic resin layer (X) of the multilayer film of the present invention may be a resin layer containing the thermoplastic resin (x) as a main component. Even a single-layer resin layer may have a multilayer structure. It may be a resin layer. Examples of the thermoplastic resin (x) used here include polyolefin resins such as polyethylene resins and polypropylene resins, polystyrene resins, polyester resins, and polyamide resins and polyimide resins when oxygen barrier properties are to be maintained. Examples thereof include a resin, a saponified resin of ethylene-vinyl acetate copolymer, and the like, and it is used for a single layer structure or a multilayer structure by mixing two or more kinds.

  Examples of the polyethylene resin include polyethylene resins such as very low density polyethylene (VLDPE), linear low density polyethylene (LLDPE), low density polyethylene (LDPE), medium density polyethylene (MDPE), and high density polyethylene (HDPE); Ethylene-vinyl acetate copolymer (EVA), ethylene-methyl methacrylate copolymer (EMMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl acrylate (EMA) copolymer, ethylene-ethyl acrylate- Ethylene copolymers such as maleic anhydride copolymer (E-EA-MAH), ethylene-acrylic acid copolymer (EAA), ethylene-methacrylic acid copolymer (EMAA); and ethylene-acrylic acid copolymer Polymer neutralized metal, ethylene-methacrylic acid copolymer Metal neutralization products of coalescence and the like.

  Examples of polypropylene resins include propylene homopolymers, copolymers of propylene and other α-olefins such as ethylene and butene, and the copolymers include random copolymers and block copolymers. Either can be used. Examples of the propylene homopolymer include isotactic polypropylene, syndiotactic polypropylene, and attack polypropylene. Among these, isotactic polypropylene is preferable.

  As these thermoplastic resins (x), polyethylene resins, polypropylene resins, and the like are preferable because they are inexpensive and excellent in moldability. In particular, the pressure-sensitive adhesive resin layer (A) and the heat-seal resin layer (B) are broken, and the interface between the thermoplastic resin layer (X) and the pressure-sensitive adhesive resin layer (A) is peeled off. When the adhesive resin layer (A) is a multilayer film exposed in a resealable state on the surface of the heat seal region, the adhesive strength between the thermoplastic resin layer (X) and the pressure-sensitive adhesive resin layer (A) Is suitable and easily peeled off, and when the heat-sealed part is peeled off, the interface peeled surface of the thermoplastic resin layer (X) and the pressure-sensitive adhesive resin layer (A) is less rough, and opening and resealing are repeated. Since the resealing strength in the case is high, an ethylene- (meth) acrylic acid copolymer such as an ethylene-acrylic acid copolymer (EAA), an ethylene-methacrylic acid copolymer (EMAA) or a metal neutralized product thereof Preferably, ethylene- (meth) acrylic acid copolymer Metal neutralized product is particularly preferred. As the metal neutralized product of the ethylene- (meth) acrylic acid copolymer, for example, at least 10 mol%, preferably 10 to 60 mol% of the carboxyl group is a metal ion such as sodium or zinc. What is summed up. In the present specification, (meth) acrylic acid means acrylic acid or methacrylic acid, and the same applies to derivatives of acrylic acid or methacrylic acid.

  Furthermore, for the thermoplastic resin layer (X), an anti-fogging agent, an antistatic agent, a thermal stabilizer, a nucleating agent, an antioxidant, a lubricant, an antiblocking agent, a release agent, and an ultraviolet absorber as necessary. In addition, components such as a colorant may be added as long as the object of the present invention is not impaired.

(Pressure-sensitive adhesive resin layer (A))
The pressure-sensitive adhesive resin layer (A) of the multilayer film of the present invention contains an amorphous polyolefin resin (a1) in which the content of an α-olefin-derived component having 3 or more carbon atoms is 50 mol% or more. Any resin layer may be used as long as it is an adhesive resin layer.

  The amorphous polyolefin-based resin (a1) may have an α-olefin-derived component content of 3 or more carbon atoms as long as it is 50 mol% or more, and in particular, an α-olefin-derived component of 3 to 20 carbon atoms. Is preferably an amorphous polyolefin resin having a content of 50 mol% or more, more preferably an amorphous polyolefin resin having an α-olefin-derived component having 3 to 12 carbon atoms and a content of 80 mol% or more. Most preferred is an amorphous polyolefin-based resin in which the content of the α-olefin-derived component having 3 to 4 atoms is 80 mol% or more.

  As the amorphous polyolefin resin (a1), for example, even if it is a homopolymer of an α-olefin having 3 or more carbon atoms, the α-olefin having 3 or more carbon atoms is a copolymer of 2 or more types. Even if it is, it may be a copolymer of an α-olefin having 3 or more carbon atoms and another monomer, or a mixture thereof. Specific examples of the amorphous polyolefin-based resin (a1) include homopolymers such as amorphous polypropylene and amorphous poly-1-butene, 50 mol% or more of 1-butene and other α-olefins, For example, a copolymer with propylene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-dexene, etc., 50 mol% or more of propylene and other α-olefins, for example, 1 And copolymers with -butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-dexene, etc., and amorphous propylene homopolymer, amorphous 1-butene Homopolymer, amorphous propylene-1-butene copolymer having a propylene-derived component content of 50 mol% or more, amorphous 1-butene-propylene copolymer having a 1-butene-derived component content exceeding 50 mol% Coalescence An amorphous 1-butene-propylene copolymer having a 1-butene-derived component content exceeding 60 mol% is particularly preferable.

  The number average molecular weight of the amorphous polyolefin resin (a1) is preferably 100,000 to 500,000, and when the amorphous polyolefin resin (a1) is a copolymer, a random copolymer Any of block copolymers may be used, but random copolymers are preferred.

  Commercially available products that can be used as the amorphous polyolefin-based resin (a1) include, for example, “Letax” from Huntsman, Inc., “Cataloy” from Sun Allomer, “Ubetak” from Ube Lexellen, Ube Industries, Ltd. “CAP”, Sumitomo Chemical Co., Ltd. “Tough Selenium” and the like can be mentioned.

  In the present invention, the amorphous property of the amorphous polyolefin-based resin (a1) is measured by a differential scanning calorimeter (DSC) using 5 mg of a sample from 20 ° C. to 230 ° C. at a heating rate of 10 ° C./min. In this case, the melting peak is not observed, and the heat of fusion of the maximum peak in the endothermic curve is 0.7 J / g or less.

Amorphous polyolefin resin (a1) has a lot of low molecular weight and sticks easily, and resin pellets are easy to adhere to each other. Although there is a problem in handling raw materials such as difficult to formulate, the content of other polyolefin resins such as α-olefin derived components having 3 or more carbon atoms is 50 mol% in order to improve the handling of the raw materials. Polyolefin resins (a4) other than the above amorphous polyolefin resin (a1) [hereinafter abbreviated as other polyolefin resins (a4). ] Are preferably used in combination. As a method of using the amorphous polyolefin resin (a1) and the other polyolefin resin (a4) in combination, the amorphous polyolefin resin (a1) and the other polyolefin resin (a4) are mixed with a twin screw extruder or the like. It is preferable to use the mixture by heat-kneading or pelletizing the amorphous polyolefin-based resin (a1) around the amorphous polyolefin-based resin (a1) beforehand with another polyolefin-based resin (a4). The mass ratio (a1) / (a4) when the amorphous polyolefin resin (a1) and other polyolefin resin (a4) are used in combination is preferably 99/1 to 60/40, and 97/3 to 80/20. Is more preferable.

  The pressure-sensitive adhesive resin layer (A) needs to be a resin layer having a good balance between tackiness and heat-resealability (under heat, for example, resealability at 50 ° C. to 90 ° C.). Therefore, a resin layer containing the amorphous polyolefin resin (a1) and the rubbery thermoplastic resin (a2) is preferable, and among them, the amorphous polyolefin resin (a1) and the rubbery thermoplastic resin (a2). And a resin layer containing the tackifier (a3) are particularly preferable.

  When the pressure-sensitive adhesive resin layer (A) is a resin layer containing an amorphous polyolefin resin (a1) and further containing a rubbery thermoplastic resin (a2) if necessary, these (a1) And (a2) are preferably used in such a ratio that the mass ratio (a1) / (a2) is 20/80 to 100/0, and in particular, a resin having a good balance between adhesiveness and heat resealability Since it becomes a layer, it is more preferable that the mass ratio (a1) / (a2) is a ratio of 30/70 to 80/20.

  When the pressure-sensitive adhesive resin layer (A) is a resin layer comprising an amorphous polyolefin resin (a1), a rubbery thermoplastic resin (a2), and a tackifier (a3), The use ratio of (a1), (a2) and (a3) is such that the mass ratio (a1) / (a2) is 20/80 to 100/0 and the mass ratio (a1 + a2) / (a3) is 50/50. The ratio is preferably -98/2. In particular, since the resin layer has a good balance between adhesiveness and heat resealability, the mass ratio (a1) / (a2) is 30 / 70-80 / 20. In addition, the mass ratio (a1 + a2) / (a3) is more preferably 60/40 to 90/10.

  In the pressure-sensitive adhesive resin layer (A), when the amorphous polyolefin resin (a1) and the other olefin resin (a4) are used in combination, the amorphous polyolefin resin (a1) and the other olefin are used. The system resin (a4) is preferably melt-kneaded and then pelletized or (a4) the resin is used so as to cover the resin (a1). The melt index (measured at 230 ° C. according to MI, JIS K-7210) of the pellets is preferably 0.1 to 30 g / 10 minutes because flow disturbance is unlikely to occur. More preferably, it is 5 to 20 g / 10 minutes.

  In the case where the rubber-like thermoplastic resin (a2) and the tackifier (a3) are used in combination in the pressure-sensitive adhesive resin layer (A), the rubber-like thermoplastic resin (a2) and the tackifier (a3) are also used. ) Is preferably kneaded and pelletized.

  The other polyolefin-based resin (a4) may be a polyolefin-based resin other than the amorphous polyolefin-based resin (a1) in which the content of the α-olefin-derived component having 3 or more carbon atoms is 50 mol% or more. For example, polypropylene resin, poly 1-butene resin, polytrimethylpentene-1 (TPX) and the like can be mentioned. Among them, polypropylene resin is preferable because it is heat resistant, has a high melting point, and is easily available. .

  The rubbery thermoplastic resin (a2) is not particularly limited as long as it is a rubbery thermoplastic resin. For example, a styrene-butadiene block copolymer (SB), a hydrogenated product thereof, styrene-butadiene- Styrene block copolymer (SBS), its hydrogenated product, styrene-isoprene-styrene block copolymer (SIS), its hydrogenated product, styrene-isoprene block copolymer (SI), its hydrogenated product styrene-ethylene -Rubber block copolymer containing styrene block such as propylene block copolymer (SEP) and its hydrogenated product; ethylene-propylene copolymer (EP), ethylene-butene-1 copolymer (EB) ), Ethylene-octene copolymer (EO), propylene-butadiene copolymer (PB), ethylene- Acid vinyl copolymer (EVA) rubber copolymer the ethylene was obtained as an essential component as such, and the like.

  Among these rubbery thermoplastic resins (a2), a rubbery block copolymer containing a styrene block and a diene block, and its hydrogenated product are preferred, have low odor, gel, fish eye, fluid disturbance, etc. Since there is no appearance defect and a co-pressed film that can be continuously produced for a long time and has good resealability is obtained, a hydrogenated styrene-butadiene block copolymer (SB), styrene-butadiene-styrene block Styrene block and diene block such as hydrogenated copolymer (SBS), hydrogenated styrene-isoprene-styrene block copolymer (SIS), hydrogenated styrene-isoprene block copolymer (SI) More preferred is a hydrogenated rubber block copolymer containing styrene-butadiene block copolymer (S ) Hydrogenated product (HSBR), styrene-butadiene-styrene block copolymer (SBS) hydrogenated product (SEBS), styrene-butadiene-styrene block copolymer (SBS) partially hydrogenated product (SBBS), Most preferred is a hydrogenated product of styrene-isoprene-styrene block copolymer (SIS) (styrene-ethylene-propylene-styrene block copolymer, SEPS).

  The hydrogenation ratio of the hydrogenated product of the rubbery copolymer is usually 10 to 100 mol%, and preferably 30 to 100 mol%. Further, the melt index (measured at 190 ° C. in accordance with MI, JIS K-7210) is preferably 2 to 30 g / 10 minutes because flow disturbance is unlikely to occur.

  Examples of the tackifier (a3) include resins having an adhesive property at room temperature made of natural resin or synthetic resin, such as natural resin rosin, polymerized rosin, hydrogenated rosin, glycerinster rosin, pentaerythritol and the like. Rosin resin; Terpene resin such as terpene, aromatic modified terpene, terpene phenol, hydrogenated terpene; Petroleum resin such as aliphatic petroleum resin, aromatic petroleum resin, hydrogenated alicyclic petroleum resin; Examples include liquid polybutadiene, polyisoprene that is liquid at normal temperature, and polyisobutylene that is liquid at normal temperature. Of these, rosin resins, terpene resins, and petroleum resins are preferable.

  The pressure-sensitive adhesive resin layer (A) may contain various additives such as softeners, oils (mineral oils), stabilizers (antioxidants, etc.), surfactants, liquid paraffin, etc. as necessary. It may be added.

(Heat seal resin layer (B))
The heat seal resin layer (B) of the multilayer film of the present invention may be a heat sealable resin layer containing the thermoplastic resin (b). Examples of the thermoplastic resin (b) used here include: Polyolefin resins such as polyethylene resins and polypropylene resins, polystyrene resins, and polyester resins can be used, and heat sealing is possible depending on the material of the heat seal part of the adherend such as a container that heat seals the multilayer film. What is necessary is just to select resin suitably.

  Examples of the polyethylene resin used as the thermoplastic resin (b) in the heat seal resin layer (B) include the polyethylene resins exemplified as the thermoplastic resin (x). Examples of the polypropylene resin include propylene and Copolymers with other α-olefins, such as propylene-ethylene copolymers and propylene-butene copolymers, can be mentioned. As these propylene-based copolymers, any of random copolymers and block copolymers can be used, but random copolymers are preferred.

  Examples of the polystyrene resin used as the thermoplastic resin (b) in the heat seal resin layer (B) include a small amount of rubber and other vinyl monomers copolymerized with polystyrene and styrene monomers. Examples thereof include styrene copolymers. Examples of other vinyl monomers include styrene monomers such as α-methylstyrene and p-methylstyrene, acrylonitrile, methyl acrylate, methyl methacrylate, acrylic acid, methacrylic acid, and maleic anhydride. Can be mentioned. Moreover, the usage-amount of a rubber part is 0.1-20 mass% normally, and the usage-amount of other vinylic monomers is 0.1-30 mass%. Preferable examples of the polystyrene resin used as the thermoplastic resin (b) include high impact polystyrene (HIPS) which is a copolymer of polystyrene and diene rubber and styrene.

  As the polyester resin used as the thermoplastic resin (b) in the heat seal resin layer (B), for example, polyester resins such as polyethylene terephthalate and polybutylene terephthalate are preferable, and polyethylene terephthalate is particularly preferable.

(Details of various configurations)
In the case of the multilayer film (α), the heat seal resin layer (B) does not require selection of a resin for peeling the interface with the pressure-sensitive adhesive resin layer (A) as in the multilayer film (β). It is possible to select and use a heat-sealable resin, preferably the same type of resin, according to the material of the heat-sealed part of the adherend such as a container. For example, when the material of the heat seal part is based on polyethylene resin, any of the above-described polyethylene resins can be used as the thermoplastic resin (b) used for the heat seal resin layer (B).

  In the multilayer film (α), for example, when the material of the heat seal part is based on polypropylene resin, the thermoplastic resin (b) used for the heat seal resin layer (B) is inexpensive and has a molding process. The above-mentioned polypropylene resins can be used because of their excellent properties, sealability, etc., among which propylene-ethylene copolymers, for example, propylene-ethylene copolymers having an ethylene-derived component content of 2 to 10% by mass are preferred. .

  In the multilayer film (α), for example, when the material of the heat seal portion is based on polystyrene resin, the thermoplastic resin (b) used for the heat seal resin layer (B) is inexpensive, moldability, From the viewpoint of excellent heat sealability and the like, the above-described polystyrene resin or polyethylene resin having adhesiveness with the polystyrene resin is preferable.

  Examples of the polyethylene resin having adhesiveness with the polystyrene resin include, for example, ethylene-vinyl acetate copolymer (EVA), very low density polyethylene (VLDPE), linear low density polyethylene (LLDPE), low density polyethylene ( LDPE), modified polyethylene obtained by mixing and modifying rosin, hydrogenated rosin, rosin ester derivatives, polymerized rosin, terpene, modified terpene resin, aliphatic petroleum resin, maleic anhydride and the like to these ethylene resins.

  Further, in the multilayer film (α), for example, when the material of the heat seal part is based on a polyester resin, the thermoplastic resin (b) used for the heat seal resin layer (B) may be moldability, seal Since it is excellent in aptitude etc., the above-mentioned polyester resin or the polyethylene resin which has adhesiveness with a polyester resin is preferable.

  Examples of the polyethylene resin having adhesiveness with the polyester resin include those similar to the polyethylene resin described above as the polyethylene resin having adhesiveness with the polystyrene resin.

  In the case of the multilayer film (β), when the heat-seal resin layer (B) is heat-sealed with a resin layer having the same composition and peeled off, the pressure-sensitive adhesive resin layer (A) and the heat-seal resin layer (B) It is necessary to select the resin configuration of the heat-seal resin layer (B) so that the interface of is easily peeled off. For this reason, as an adherend such as a container, it is necessary to select an adherend having a heat sealable heat seal portion.

  In the multilayer film (β), as a combination in which the interface between the pressure-sensitive adhesive resin layer (A) and the heat seal resin layer (B) easily peels, the adhesive strength at these interfaces is 2 to 20 N / 15 mm, And the combination which becomes smaller than the adhesive strength in the interface of a thermoplastic resin layer (X) and a pressure sensitive adhesive resin layer (A) can be mentioned. The adhesive strength at this interface is an adhesive strength that can maintain the function as a multilayer film and that can be peeled relatively easily. To do this, the heat seal resin layer (B) has a moderate adhesiveness with the pressure-sensitive adhesive resin layer (A), and the adhesive strength of these heat seal resins is reduced to about 2 to 20 N / 15 mm. A layer may be selected and combined with the pressure-sensitive adhesive resin layer (A). As such a heat seal resin layer, for example, ethylene- (meth) acrylic acid such as ethylene-acrylic acid copolymer (EAA), ethylene-methacrylic acid copolymer (EMAA) as the thermoplastic resin (b). A copolymer or a metal neutralized product thereof is preferable, and a resin layer using a metal neutralized product of an ethylene- (meth) acrylic acid copolymer comprises a pressure-sensitive adhesive resin layer (A) and a heat seal resin layer ( B) The adhesive strength at the interface is appropriate and peels easily, and the peeled surface of the pressure-sensitive adhesive resin layer (A) and the heat seal resin layer (B) is less rough when the heat seal part is peeled off. The re-sealing strength when opening and resealing is high is particularly preferable.

  In the multilayer film (β), the thermoplastic resin layer (X) may be a resin layer containing the thermoplastic resin (x) as a main component, but with the pressure-sensitive adhesive resin layer (A). It is necessary that the resin layer has an adhesive strength at the interface larger than the adhesive strength between the pressure-sensitive adhesive resin layer (A) and the heat seal resin layer (B). For this reason, as the thermoplastic resin (x) used in the thermoplastic resin layer (X), the adhesive strength between the thermoplastic resin layer (X) and the pressure-sensitive adhesive resin layer (A) is a pressure-sensitive adhesive resin layer (A ) And the heat seal resin layer (B), it is preferable to select an appropriate resin in consideration of being larger than the adhesive strength. For example, a polyolefin resin such as a polyethylene resin or a polypropylene resin, a polystyrene resin, Examples thereof include polyester resins, polyethylene resins having adhesiveness with polyester resins, polystyrene resins or polyethylene resins having adhesiveness with polystyrene resins. Of these, polyethylene resins are preferred.

  As said polyethylene-type resin, the polyethylene-type resin mentioned above as a thermoplastic resin (x), and the polyethylene-type resin which has adhesiveness with a polystyrene type and a polyester-type resin can be used. Examples of the polypropylene resin include a copolymer of propylene and another α-olefin, such as a propylene-ethylene copolymer and a propylene-butene copolymer. Further, in order to increase the adhesive strength between the thermoplastic resin layer (X) and the pressure-sensitive adhesive resin layer (A), a resin obtained by graft-polymerizing an adhesive resin such as maleic anhydride to an olefin, or the above-mentioned adhesive An appropriate amount of the imparting agent (a3) may be added.

  In the case of the multilayer film (γ), when the heat-seal resin layer (B) is heat-sealed with a resin layer having the same composition and peeled off, the pressure-sensitive adhesive resin layer (A) and the heat-seal resin layer (B) Ruptures at the boundary between the heat-sealed part and the non-heat-sealed part and peels off the interface between the thermoplastic resin layer (X) and the pressure-sensitive adhesive resin layer (A). It is necessary that the adhesive strength at the interface with the pressure-adhesive resin layer (A) be a resin layer that is greater than the adhesive strength at the interface between the thermoplastic resin layer (X) and the pressure-sensitive adhesive resin layer (A). . For this reason, the thermoplastic resin (b) used in the heat seal resin layer (B) is a resin that can be heat sealed (heat fusion) according to the material of the heat seal portion of the adherend such as a container, preferably the same kind It is preferable to select and use a resin having high adhesive strength with the pressure-sensitive adhesive resin layer (A) from among the resins, and the heat described as the resin used for the heat seal resin layer (B) in the multilayer film (α) Any of the plastic resins (b) can be used in the same manner.

  With respect to such a heat seal resin layer (B), the thermoplastic resin layer (X) of the multilayer film (γ) is peeled off by heat sealing the heat seal resin layer (B) with a resin layer of the same composition. In this case, it is necessary to select the resin configuration of the thermoplastic resin layer (X) so that the interface between the thermoplastic resin layer (X) and the pressure-sensitive adhesive resin layer (A) can be easily peeled off.

In the multilayer film (γ), as a combination in which the interface between the thermoplastic resin layer (X) and the pressure-sensitive adhesive resin layer (A) easily peels, the adhesive strength (P _XA ) is 2 to 23 N / 15 mm. Moreover, the combination which becomes smaller than the adhesive strength ( _PAB ) of a pressure-sensitive-adhesive resin layer (A) and a heat seal resin layer (B) can be mentioned. This adhesive strength is an adhesive strength that can maintain the function as a multilayer film and that can be peeled relatively easily. To do this, the thermoplastic resin layer (X) has a moderate adhesiveness with the pressure-sensitive adhesive resin layer (A), and the surface resin layer whose adhesive strength is reduced to about 2 to 23 N / 15 mm. May be selected and combined with the pressure-sensitive adhesive resin layer (A). As such a surface resin layer, for example, as a thermoplastic resin (x), an ethylene- (meth) acrylic acid copolymer such as an ethylene-acrylic acid copolymer (EAA) or an ethylene-methacrylic acid copolymer (EMAA) is used. A polymer or a metal neutralized product thereof is preferable, and a resin layer using a metal neutralized product of an ethylene- (meth) acrylic acid copolymer is composed of a thermoplastic resin layer (X) and a pressure-sensitive adhesive resin layer (A When the heat-sealed part is peeled off, the peeled surface of the thermoplastic resin layer (X) and the pressure-sensitive adhesive resin layer (A) is less rough and can be opened. And re-sealing strength when repeated is particularly preferred.

  In the multilayer film of the present invention described above, as the thermoplastic resin (b), polyolefin resins such as polyethylene resins and polypropylene resins, polystyrene resins such as polystyrene and high impact polystyrene (HIPS), polyethylene terephthalate, etc. When using a polyester resin, it is excellent in adhesion between the container and the lid, stability of the sealing strength, etc., and in accordance with JIS K-7210, it is 190 ° C. for the polyethylene resin and 230 ° C. for the polypropylene resin system. The polystyrene resin preferably has an MI (melt index) measured at 200 ° C. and a polyester resin at 260 ° C. of 2 to 80 g / 10 minutes.

  As the heat seal resin layer (B), in consideration of processability at the time of film formation and packaging suitability of the filling machine, the heat seal resin layer (B) has a friction coefficient of 0.7 or less, particularly 0.5 or less. It is desirable to be. For this reason, it is preferable to add a lubricant and an antiblocking agent to the heat seal resin layer (B) as appropriate.

  In addition, the surface of the heat seal resin layer (B) contains low molecular weight components from the amorphous polyolefin resin (a1) and the tackifier (a3) in the pressure sensitive adhesive resin layer (A) over time. In some cases, burts (precipitation) may occur, resulting in deterioration of slipperiness and blocking of the film. As a solution, it is effective to emboss the surface of the multilayer film and to add a filler to the heat seal resin layer (B). As the filler, inorganic materials such as calcium carbonate and talc are desirable because they are in a state where large irregularities are expressed on the price and surface, and a good friction coefficient can be maintained.

  Furthermore, for the heat seal resin layer (B), an anti-fogging agent, an antistatic agent, a heat stabilizer, a nucleating agent, an antioxidant, a lubricant, an antiblocking agent, a release agent, and an ultraviolet absorber as necessary. Further, a colorant and the like may be added within a range not impairing the object of the present invention.

  In the case of the multilayer films (α) and (γ), peeling does not occur at the interface between the pressure-sensitive adhesive resin layer (A) and the heat seal resin layer (B) when the heat seal portion is peeled off. Therefore, even when additives such as lubricants and antiblocking agents are added to the heat seal resin layer (B), there is no effect on the interfacial peeled portion due to the addition of lubricants and antiblocking agents, etc. In addition, there is an advantage that a multilayer film having a stable reseal adhesive strength can be obtained.

(Method for producing multilayer film)
The method for producing the multilayer film of the present invention is not particularly limited. For example, (1) an amorphous polyolefin-based film is formed on a film for a thermoplastic resin layer (X) containing the thermoplastic resin (x). A pressure-sensitive adhesive resin layer (A) comprising a resin (a1) and, if necessary, a rubbery thermoplastic resin (a2), a tackifier (a3), another polyolefin resin (a4), and the like; A method of laminating in the order of (X) / (A) / (B) by simultaneously heat-melt-extruding the heat-seal resin layer (B) containing the thermoplastic resin (b) (heat-melt extrusion coating method) ) And (2) a resin for the thermoplastic resin layer (X) containing the thermoplastic resin (x), an amorphous polyolefin resin (a1), and if necessary, a rubbery thermoplastic resin (a2) , Tackifiers (a3), other polyolefins A resin for a pressure-sensitive adhesive resin layer (A) comprising a resin based resin (a4) and a resin for a heat seal resin layer (B) comprising a thermoplastic resin (b), respectively. It is heated and melted in another extruder, and is laminated in the order of (X) / (A) / (B) in a molten state by a known method such as a co-extrusion multilayer die method or a feed block method. Examples include coextrusion method in which film is coextruded and laminated by the chill roll method, among others, and it is possible to adjust the interfacial adhesive strength between each layer relatively freely, with excellent hygiene and good cost performance. The coextrusion method (2) is preferable because a multilayer film can be obtained. In order to improve printing adhesiveness and laminating suitability, it is desirable to subject the thermoplastic resin layer (X) to a surface treatment.

  Examples of the surface treatment include corona treatment, plasma treatment, chromic acid treatment, flame treatment, hot air treatment, surface oxidation treatment such as ozone / ultraviolet treatment, and surface unevenness treatment such as sandblasting, but corona treatment is preferred. is there.

  In the method for producing a multilayer film as described above, when the rubber-like thermoplastic resin (a2) is used as the pressure-sensitive adhesive resin layer (A), a styrene block and a diene block are used as the rubber-like thermoplastic resin (a2). It is preferable to use a hydrogenated rubber-based block copolymer that contains bismuth because it is excellent in thermal stability and can be produced stably for a long time. Further, in the method for producing a multilayer film by this coextrusion method, since the pressure-sensitive adhesive resin layer (A) is sandwiched between the thermoplastic resin layer (X) and the heat seal resin layer (B), it is usually 200 ° C. There is an advantage that it is difficult to receive a direct heat history from a feed block or a die heated to a high temperature exceeding 1, and that gel, fish eye, flow turbulence and the like are hardly generated in the pressure-sensitive adhesive resin layer (A).

  In the multilayer film of the present invention, as a preferable combination of each resin layer, for example, a surface resin layer using a polyethylene-based resin or a polypropylene-based resin, and a content of an α-olefin-derived component having 3 to 12 carbon atoms Resin layer comprising a hydrogenated rubber block copolymer containing an amorphous polyolefin resin of 80 mol% or more, a polystyrene block and a polydiene block, a tackifier (a3), and a polypropylene resin And a combination of a heat seal resin layer using a polyethylene resin, a polypropylene resin, a polystyrene resin, or a polyethylene resin having adhesiveness with a polystyrene resin or a polyester resin. Among these, what used 1 or more types of resin chosen from the group which consists of rosin resin, terpene resin, and petroleum resin as a tackifier (a3) in a pressure sensitive adhesive resin layer (A). Particularly preferred.

(Adhesive strength and film thickness)
In addition, in the multilayer film of the present invention, it is important to appropriately select a combination of each resin layer in order to achieve a target adhesive strength. In this case, the adhesive strength also changes depending on the thickness of the resin layer. It is also necessary to consider. Even if the pressure-sensitive adhesive resin layer (A) and the heat seal resin layer (B) are used in a combination that is relatively excellent in adhesiveness, for example, it is composed of a metal neutralized product of an ethylene- (meth) acrylic acid copolymer. In the case of a heat seal resin layer, if the thickness is as small as 0.1 to 0.5 μm, the adhesive strength with the pressure-sensitive adhesive resin layer (A) is greatly reduced, and conversely if it is greater than 30 μm, the adhesive strength is reduced. It becomes a big value without doing. The thickness of the multilayer film (multilayer structure part II) of the present invention is usually in the range of 20 to 200 μm including the thickness usually referred to as a sheet, and more preferably in the range of 20 to 70 μm.

  Among the multilayer films of the present invention, the multilayer film (α) is not peeled off at the interface, so the adhesive strength between the thermoplastic resin layer (X) and the pressure-sensitive adhesive resin layer (A), and the sensitivity The adhesive strength between the pressure-adhesive resin layer (A) and the heat seal resin layer (B) is preferably 20 N / 15 mm or more.

  Moreover, as said multilayer film ((beta)), it is preferable that the adhesive strength of a pressure-sensitive-adhesive resin layer (A) and a heat seal resin layer (B) is 2-20 N / 15mm, Especially, 2-18 N / 15mm It is more preferable that In this case, the adhesive strength between the thermoplastic resin layer (X) and the pressure-sensitive adhesive resin layer (A) of the multilayer film (β) is that of the pressure-sensitive adhesive resin layer (A) and the heat seal resin layer (B). It is preferably 5 N / 15 mm or more larger than the adhesive strength. The thickness of the heat seal resin layer (B) of the multilayer film (β) is preferably 0.6 to 10 μm, more preferably 1 to 10 μm, and most preferably 1 to 6 μm.

  Further, as the multilayer film (γ), the adhesive strength between the thermoplastic resin layer (X) and the pressure-sensitive adhesive resin layer (A) is preferably 2 to 23 N / 15 mm, particularly 2 to 18 N / 15 mm. It is more preferable that In this case, the adhesive strength between the pressure-sensitive adhesive resin layer (A) and the heat seal resin layer (B) of the multilayer film (β) is that of the thermoplastic resin layer (X) and the pressure-sensitive adhesive resin layer (A). It is preferably 5 N / 15 mm or more larger than the adhesive strength. The total thickness of the pressure-sensitive adhesive resin layer (A) and the heat seal resin layer (B) of the multilayer film (γ) is preferably 3 to 30 μm, and more preferably 3.5 to 23 μm. It is preferably 4 to 20 μm and most preferably. The thickness of the heat seal resin layer (B) is preferably 0.6 to 10 μm, more preferably 1 to 10 μm, and most preferably 1 to 6 μm. The total thickness of the thermoplastic resin layer (X), the pressure-sensitive adhesive resin layer (A), and the heat seal resin layer (B) is preferably 20 to 70 μm.

(Multilayer structure (I))
In addition, since the packaging material having resealability using the multilayer film of the present invention can prevent the risk of being resealed and displayed for sale after being opened, the trace at the time of opening can be easily identified. Preferably there is.

Next, the multilayer structure portion (I) will be described.
(Base material layer support (C))
The substrate layer support (C) used in the multilayer sheet of the present invention is not limited in type, and examples thereof include plastic films such as polyolefin, polyester, polyvinyl chloride, and fluororesin, but they are high in strength and inexpensive. Transparent or translucent biaxially oriented polypropylene or polyethylene terephthalate is preferably selected.

  Furthermore, the surface of the base material layer support (C) may be subjected to easy adhesion treatment, mat treatment, etc. for the purpose of improving the printing adhesion or showing the peeling display more clearly. Printing or the like can be performed to such an extent that the peeling detection display is not hidden. The thickness of the base material layer support (C) is not particularly limited. However, if the thickness is too thin, the stress at the time of peeling is dispersed to reduce the character development, and if it is too thick, the rigidity becomes high and the peeling becomes difficult. It is 25-300 micrometers, More preferably, it is 38-100 micrometers. The physical properties of the base material layer support (C) are not particularly limited. However, if it is too flexible, the stress at the time of peeling is dispersed and the character development is reduced, so that it is difficult to stretch.

(Peeling layer (D))
The release layer (D) used in the multilayer sheet of the present invention has an adhesion between the release layer (D) and the base material layer support (C), or an adhesion between the release layer (D) and the colored layer (E). Use a transparent ink with a relatively weak cohesive strength or a transparent ink with a weak cohesive force, etc., and use a method such as printing on a pattern such as “VOID” or “opened” to laminate it on the base material layer support (C). It can produce by this method.

  The release layer (D) is formed on the substrate layer support (C) using a known and usual means such as letterpress printing, flexographic printing, gravure printing or screen printing. The ink for forming the release layer (D) may be appropriately selected and used from UV curable ink, solvent-dried ink, and the like. For example, acrylic resin, polyvinyl alcohol, polyester, polystyrene, cellulose, For example, a wax, a filler, or a pigment can be used in which a resin such as vinyl acetate, urethane resin, or silicone resin is dissolved or dispersed in a solvent. Various additives such as a stabilizer, a crosslinking agent, and a photoinitiator can be added. Moreover, in order to form ink on a base-material layer support body (C), using the method of drying by heating after printing using the ink containing a solvent, or the type of ink which hardens | cures by irradiation of an ultraviolet-ray, an electron beam, etc. A method of irradiating ultraviolet rays or electron beams after printing can be used.

(Colored layer (E))
The multilayer structure part (I) must have at least a base layer support (C) and a release layer (D) on a part of the base layer support (C). In order to show clearly, it is preferable to have a colored layer (E) on the entire surface or a part of the substrate layer support (C) so as to cover the release layer (D).

  Examples of the method for forming the colored layer (E) include a method of printing or coating inks such as gravure ink and planographic / letter printing ink, a method of coating a metal by sputtering or vapor deposition, and the like. For the purpose of increasing the adhesive strength with the support (C), after performing a surface treatment such as a corona treatment in advance, it can be laminated using the forming method or the like.

  The colored layer (E) is not particularly limited, and for example, a layer of ink containing a color material may be laminated as a single layer, and the base material covers the release layer (D). The structure which consists of several layers which formed the contact bonding layer in the whole surface or a part of layer support body (C), and laminated | stacked the colored film on this contact bonding layer may be sufficient. In particular, as the colored layer (E), an ink having a large adhesive force with respect to the base material layer support (C) is preferably used. The resin component of the ink includes a mixture of vinyl chloride / vinyl acetate copolymer copolymerized with vinyl alcohol, urethane resin, acrylic resin, nitrocellulose and the like, and the hydroxyl value is preferably about 1 to 10. Furthermore, in order to improve the adhesive force with a film, it can also bridge | crosslink. Moreover, when forming a colored layer (E) by vapor deposition or sputtering, well-known and usual metals, such as aluminum, nickel, chromium, silver, etc. can be used.

(Color material)
In the case of using an ink for the colored layer (E), a known and commonly used pigment / dye can be used, and it is not particularly limited, but the total light reflectivity is used for the purpose of showing the peeling display more clearly. A low dark color is preferably selected.

(Thickness of colored layer (E))
The colored layer (E) needs to have a thickness of a certain level or more in order to obtain a concentration, and preferably in order to provide a concealing property. On the other hand, when the ink layer is too thick, the transmission of the peeling force to the peeling layer (D) when peeling the multilayer sheet having a resealing function is deteriorated, and the expression of peeling display is lowered. Accordingly, the thickness of the colored layer (E) is preferably 0.3 to 20 μm, more preferably 1 to 3 μm.

(Relationship between interfacial bond strength between layers)
In the embodiment of FIG. 2, for example, in the case of the embodiment of FIG. D) Adhesive force (1) ′ between the thermoplastic resin layer (X), adhesive force (2) between the base material layer support (C) and the thermoplastic resin layer (X), and a thermoplastic resin layer ( X) and the pressure-sensitive adhesive resin layer (A), or the pressure-sensitive adhesive resin layer (A) and the heat seal resin layer (B), whichever is lower, (3) The relationship between the heat seal resin layer (B) and the adherend (4) between the heat seal resin layer (B) and the adherend that can be heat sealed is (1) <(3) <(2) and (1) <(3) <(4), or (1) '<(3) <(2) and (1)'<(3)<(4) Is preferred.

  In the case of the embodiment of FIG. 3, the adhesive force (1) between the base material layer support (C) and the release layer (D), and the adhesive force between the release layer (D) and the colored layer (E) (1 ) '', An adhesive force (5) between the base material layer support (C) and the colored layer (E), an adhesive force (6) between the thermoplastic resin layer (X) and the colored layer (E), Adhesion of thermoplastic resin layer (X) and pressure sensitive adhesive resin layer (A), or pressure sensitive adhesive resin layer (A) and heat seal resin layer (B), whichever is lower Relationship between force (3) and adhesive force (4) between heat seal resin layer (B) and adherend when heat seal resin layer (B) and heat sealable adherend are heat sealed (1) <(3) <(4) and (1) <(3) <(5) and (1) <(3) <(6) or (1) '' <(3) <( 4) and (1) '' <(3) <(5) and (1) '' <(3) <(6).

(Middle layer)
In the multilayer sheet of the present invention, a reinforcing layer (G) and an adhesive layer (F) can be provided as necessary. In this case, a single-layer or multi-layer structure portion (hereinafter referred to as an intermediate layer) composed of one or more layers selected from the thermoplastic resin layer (X), the reinforcing layer (G), the adhesive layer (F), and the colored layer (E). For the purpose of increasing the reliability that the pressure-sensitive adhesive resin layer (A) is exposed at the peeling interface of the heat seal portion, the intermediate layer preferably has a high breaking strength in the surface direction. If the rupture strength is too low, the peel-off display part may remain broken on the adherend side. In this case, a part where the pressure-sensitive adhesive resin layer (A) is not exposed at the peel interface of the heat seal part occurs. This is not preferable because it is difficult to sufficiently reseal.

  Moreover, in order to increase the reliability of resealability, it is preferable that the intermediate layer does not extend too much in the surface direction due to stress at the time of opening. When the intermediate layer is excessively stretched due to stress at the time of opening, even when the breaking strength is sufficiently large, the peel-off display portion is stretched and wrinkles and the like are generated. Therefore, the pressure-sensitive adhesive resin layer (A) Even if it can be exposed to the peeling interface of the heat seal portion, it is not preferable because it becomes difficult to re-seal sufficiently.

  Furthermore, for the purpose of increasing the reliability that the peel indication is clearly manifested when the heat seal part is peeled off, the intermediate layer preferably undergoes some deformation in the surface direction due to stress at the time of opening. Furthermore, it is preferable that the base material layer support (C) is more flexible. If the flexibility is too low, the stress at the time of peeling off the heat seal portion is not transmitted to the peeling layer (D), and it is not preferable because peeling indication is difficult to appear.

(Reinforcing layer (G))
As the intermediate layer, it is preferable to select one having a balance between the breaking strength and the flexibility as described above. For this purpose, the intermediate layer is reinforced between the release layer (D) and the thermoplastic resin layer (X). It is preferable to laminate the layer (G).

(Type of reinforcement layer (G))
When the reinforcing layer (G) is used in the multilayer sheet having the resealing function of the present invention, the type is not particularly limited. For example, EVA, nylon, polyurethane, polyolefin, polyester, polyvinyl chloride, fluororesin, etc. A single layer or multilayer film as a main component can be exemplified.

  Further, the thickness of the reinforcing layer (G) is not particularly limited, but generally, if it is too thin, the tensile strength is lowered, so that it is easy to break, and if it is too thick, the rigidity becomes high and it is difficult to deform. 100 μm, more preferably 5 to 60 μm.

  Among these, 6 to 12 μm polyethylene terephthalate, 10 to 40 μm biaxially stretched polypropylene, 20 to 60 μm unstretched polypropylene, and the like are preferably selected. Further, in order to improve adhesiveness, the surface thereof may be subjected to corona treatment, easy adhesion coating treatment, or the like, or may be subjected to coloring, design, printing, or the like. Furthermore, additives such as colorants and antistatic agents can be added.

(Lamination method of multilayer structure part (I) and multilayer structure part (II))
The method for laminating the multilayer structure part (I) and the multilayer structure part (II) is not particularly limited, but the multilayer structure part (II) is laminated on the multilayer structure part (I) at the time of coextrusion molding to obtain a laminated sheet. A method, a multilayer structure portion (I) and a multilayer structure portion (II), which have been laminated in advance, and an adhesive layer (F) applied to one of the layers and dried, and a device such as a heating laminator as necessary The method of bonding using can be illustrated. In addition, a pressure-sensitive adhesive is applied and dried as an adhesive layer (F) on the release paper, and the adhesive layer (F) formed on the release paper is placed on the side of the release layer of the multilayer structure portion (I), such as a laminator. Then, the multilayer structure portion (II) can be bonded together using an apparatus such as a laminator while peeling the release paper.

  Further, when the reinforcing layer (G) is used in the multilayer sheet of the present invention, the multilayer structure portion (I) and the reinforcing layer (G) are applied and an adhesive layer (F) is applied and dried on any of the layers. In addition, bonding is performed using an apparatus such as a heating laminator as necessary, and the other surface of the reinforcing layer (G) and the multilayer structure portion (II) are bonded to either layer as an adhesive layer (F Examples of a method of applying and drying ') and pasting together using an apparatus such as a heating laminator can be exemplified.

  In particular, the inventors have intensively studied and estimated the mechanism of release indication, and when a pressure-sensitive adhesive having a thickness of 5 to 40 μm is used as the adhesive layer (F and / or F ′) in the multilayer sheet of the present invention. The adhesive layer (F and / or F ′) is more than the gap necessary for the development of the peel indication (d) in the thickness direction due to the peeling stress when the multilayer sheet of the present invention is heat sealed to the adherend and peeled off. It is considered that peeling display is easily developed by elastic deformation, which is a preferred embodiment.

  In order to increase the reliability of the resealability of the multilayer sheet of the present invention, the adhesive strength between the multilayer structure part (I) and the multilayer structure part (II) is preferably 2N / 15 mm or more, more preferably Is 5 N / 15 mm or more, more preferably 10 N / 15 mm or more, and most preferably 23 N / 15 mm or more.

  The method for laminating and bonding the multilayer structure part (I) and the multilayer structure part (II) is not particularly limited as long as a predetermined adhesive strength can be obtained. For example, wet lamination, non-solvent lamination, dry lamination, Examples include extrusion lamination and thermal lamination. Examples of the dry lamination adhesive include a polyester-polyurethane adhesive and a polyether-polyurethane adhesive. An acrylic adhesive may be used.

Examples will be described in detail below.
(Example 1)
(Manufacture of multilayer structure part (I))
As the base material layer support (C), a transparent release ink mainly composed of a toluene solution of polymethyl methacrylate (PMMA) is applied to one surface of a transparent polyester film (“Lumirror” manufactured by Toray Industries, Inc.) having a thickness of 50 μm. It printed on the pattern of "opened" with the gravure printing machine, and produced the peeling layer (D) with a dry film thickness of about 2 micrometers partially. Further, a blue gravure ink (“Univia” manufactured by Dainippon Ink & Chemicals, Inc.) was applied and dried on the entire surface of the polyester film as a colored layer (E) so that the dry film thickness was about 2 μm.

  12mm thick transparent polyester film ("Lumirror" manufactured by Toray Industries Inc.) with corona treatment applied to both sides in advance is used as the reinforcing layer (G), and the thickness after drying is used as the adhesive layer (F ') on one side. Acrylic pressure-sensitive adhesive with a thickness of 30 μm (addition of 2 parts by weight of Dainippon Ink Chemical Co., Ltd.'s isocyanate-based cross-linking agent Barnock NC-40 to Dainippon Ink & Chemicals' Quick Master SPS-1068) Was applied and dried, and bonded to the colored layer (E) surface side of the base material layer support (C) to obtain a multilayer structure portion (I).

(Production of multi-layer structure (II))
Zinc neutralized product (ionomer resin) of ethylene-methacrylic acid copolymer having a density of 0.94 g / cm ³ was used as the resin for the thermoplastic resin layer (X) (1652 manufactured by Mitsui DuPont Polychemical Co., Ltd.). As a resin for the pressure-sensitive adhesive resin layer (A), 80 parts by mass of an amorphous polypropylene resin (Ubetac UT2780 manufactured by Ube Rexelen Co., Ltd.) and a homopropylene (HOPP) having a density of 0.90 g / cm ³ (Mitsui Chemicals, Inc. ) FM121A manufactured by company) Pellets (1) obtained by melting and kneading 20 parts by mass with a twin screw extruder and 1,2-bond portions of styrene-butadiene-styrene block copolymer (SBS) are selectively used. Hydrogenated selective hydrogenated product having a hydrogenation rate of 40 mol% [styrene-butadiene-butylene-styrene block copolymer (SBBS)] (manufactured by Asahi Kasei Corporation) Futec P) 70 parts by mass, terpene resin [Yasuhara Chemical Co., Ltd. terpene resin, YS Resin PX1150] 29.5 parts by mass and phenolic antioxidant 0.5 part by mass are melt-kneaded with a twin screw extruder and pelletized. Using a resin mixture (12) obtained by dry blending the pellets (2) with a mixing ratio (1) / (2) of the pellets (1) and (2) of 50/50, a heat seal resin layer ( B) Medium density polyethylene resin with a density of 0.93 g / cm ³ (F234 manufactured by Ube Industries, Ltd.), erucic acid amide (lubricant) and natural silica (anti-blocking agent), erucic acid amide concentration of 600 ppm, natural Using the resin mixture (3) added and mixed at a ratio of silica concentration of 2000 ppm, (X) layer extruder (caliber 50 mm), (A) layer extruder (caliber 50 mm) , (B) a layer extruder (40 mm in diameter) and a T die / chill roll coextrusion multilayer film production apparatus each having a feed block are supplied to each extruder, at a temperature of 200 to 230 ° C., at a feed block and a T die Co-melt extrusion is performed at a temperature of 270 ° C., and a three-layer configuration of X / A / B, each layer has an average thickness of 30 μm / 15 μm / 5 μm, an overall thickness of 50 μm, and a heat seal resin layer (B) A multilayer structure (II) having a surface friction coefficient of 0.6 was obtained. Further, the corona treatment was applied to the thermoplastic resin layer (X) side. The interface strength of the thermoplastic resin layer (X) and the pressure-sensitive adhesive resin layer (A) of the obtained multilayer structure part (II) is 10 N / 15 mm, the pressure-sensitive adhesive resin layer (A) and the heat seal resin ( The interfacial adhesive strength of B) was 14 N / 15 mm. When the heat seal resin (B) is heat-sealed with a resin layer having the same composition and peeled off, the multilayer structure portion (II) has a heat seal resin layer (B) at the boundary between the heat seal portion and the non-heat seal portion. The pressure-sensitive adhesive resin layer (A) is also broken and the interface between the thermoplastic resin layer (X) and the pressure-sensitive adhesive resin layer (A) is peeled off, and the pressure-sensitive adhesive resin layer (A) Was a multilayer film exposed in a resealable state on the surface of the heat seal region.

  In addition, when the amorphous propylene-based resin Ubetak UT2780 5 mg was used and measured at a temperature increase rate of 10 ° C./min from 20 ° C. to 230 ° C., no melting peak was observed, and the heat of fusion of the maximum peak in the endothermic curve was 0. 0.7 J / g or less.

  On the thermoplastic resin layer (X) of the multilayer structure part (II), as an adhesive layer (F), a dry laminate adhesive (30 parts by mass of “Dick Dry LX-500” manufactured by Dainippon Ink & Chemicals, Inc.) is crosslinked. 2 parts by weight of the agent “KR-90S” and 68 parts by weight of ethyl acetate) were mixed and stirred so that the thickness after drying was 2 μm. After coating and drying at 8, the multilayer sheet of Example 1 was prepared by laminating the reinforcing layer (G) side surface of the multilayer structure portion (I) and 40 ° C. by heating.

The multilayer sheet produced in Example 1 was tested by the method shown below.
(1) Character development test When the produced multilayer sheet was heat-sealed on a polyethylene sheet having a thickness of 1 mm and peeled by hand, the state of appearance of a peel detection display of “opened” was visually confirmed.
(2) Resealability test In the above-mentioned character formation test, the multilayer sheet once peeled was again pressed against the adherend by hand to confirm whether it could be resealed.

  The multilayer sheet of Example 1 was evaluated well for both (1) lettering and (2) resealability.

It is sectional drawing of one Example of the multilayer sheet of this invention. It is sectional drawing of one Example of the multilayer sheet of this invention. It is sectional drawing of one Example of the multilayer sheet of this invention. It is sectional drawing of one Example of the multilayer sheet of this invention. It is sectional drawing of one Embodiment which shows the state which peeled the part after heat-sealing the multilayer sheet of this invention to a to-be-adhered body. It is sectional drawing of one Embodiment which shows the state which peeled the part after heat-sealing the multilayer sheet of this invention to a to-be-adhered body.

Explanation of symbols

I: Multi-layer structure (I)
II: Multilayer structure (II)
A: Pressure sensitive adhesive resin layer B: Heat seal resin layer X: Thermoplastic resin layer C: Substrate layer support D: Release layer E: Colored layer F: Adhesive layer F ′: Adhesive layer G: Reinforcing layer H: Substrate d: peeling indication h: heat seal portion

Claims (14)

A multilayer sheet having both a peel detection function and a reseal function,
A pressure-sensitive adhesive resin layer (A) and a heat seal resin layer (B) in contact therewith,
When heat-sealing the heat-sealable resin layer (B) and the heat-sealable adherend, and then peeling a part of the multilayer sheet from the adherend,
At least the heat seal resin layer (B) breaks at the boundary between the heat seal portion and the non-heat seal portion,
The pressure-sensitive adhesive resin layer (A) peels off at the interface from the adjacent layer, or the pressure-sensitive adhesive resin layer (A) peels off due to cohesive failure in the layer over the entire heat seal portion. A multilayer sheet having a peeling detection function and a resealing function. The multilayer sheet is
A multilayer structure part (I) having a peeling detection function;
A multilayer having a reseal function in which a thermoplastic resin layer (X), a pressure-sensitive adhesive resin layer (A), and a heat seal resin layer (B) are laminated in the order of (X) / (A) / (B) With a structural part (II),
The peeling detection function and the resealing function according to claim 1, wherein the multilayer structure part (I) and the multilayer structure part (II) are laminated via the thermoplastic resin layer (X). Multi-layer sheet. The multilayer sheet is overlaid on the adherend so that the heat seal resin layer (B) and the heat sealable adherend are in contact with each other, and a part of the heat seal resin layer (B) is heat sealed, Then, when peeling a part of the multilayer sheet from the adherend,
The pressure-sensitive adhesive resin layer (A) and the heat seal resin layer (B) break at the boundary between the heat seal portion and the non-heat seal portion,
The peeling according to claim 2, wherein the interface between the thermoplastic resin layer (X) and the pressure-sensitive adhesive resin layer (A) is peeled and the pressure-sensitive adhesive resin layer (A) is in a re-sealable state. A multilayer sheet having a detection function and a reseal function. The interface adhesive strength (P _XA ) between the thermoplastic resin layer (X) and the pressure-sensitive adhesive resin layer (A) is 2 to 23 N / 15 mm,
And the interfacial adhesive strength (P _XA ) is smaller than the interfacial adhesive strength (P _AB ) between the pressure-sensitive adhesive resin layer (A) and the heat seal resin layer (B),
Furthermore, the combined thickness of the pressure-sensitive adhesive resin layer (A) and the heat seal resin layer (B) is 3 to 30 μm,
The peeling detection function and re-sealing according to claim 3, wherein a total thickness of the thermoplastic resin layer (X), the pressure-sensitive adhesive resin layer (A), and the heat seal resin layer (B) is 20 to 70 µm. Multi-layer sheet with a stop function. The thermoplastic resin layer (X) is a resin layer containing an ethylene- (meth) acrylic acid copolymer or a metal neutralized product thereof,
And the pressure-sensitive adhesive resin layer (A) is a resin layer containing an amorphous olefin resin (a1) or a rubbery thermoplastic resin (a2),
Furthermore, the said heat seal resin layer (B) is a resin layer containing a polyethylene-type resin, a polypropylene-type resin, a polyester-type resin, or a polystyrene-type resin, The peeling detection function in any one of Claim 2, 3 or 4 and A multilayer sheet having a reseal function. The multilayer sheet having a peeling detection function and a reseal function according to claim 5, wherein the pressure-sensitive adhesive resin layer (A) is a resin layer further containing a tackifier (a3). The multilayer sheet having a peeling detection function and a resealing function according to claim 6, wherein the tackifier (a3) is at least one resin selected from the group consisting of a rosin resin, a terpene resin and a petroleum resin. The multilayer structure portion (I) includes a transparent or translucent base material layer support (C) and a release layer (D) formed on a part of one side of the base material layer support (C).
The one side of the said base material layer support body (C) in which the said peeling layer (D) is formed is laminated | stacked on the said thermoplastic resin layer (X), The claim 2, 3, 4, 5, 6 or A multilayer sheet having a peeling detection function and a resealing function according to any one of 7. Adhesive force (1) between the base material layer support (C) and the release layer (D),
Adhesive force (1) ′ between the release layer (D) and the thermoplastic resin layer (X);
Adhesive force (2) between the base material layer support (C) and the thermoplastic resin layer (X);
Either the adhesive force between the thermoplastic resin layer (X) and the pressure-sensitive adhesive resin layer (A) or the adhesive force between the pressure-sensitive adhesive resin layer (A) and the heat seal resin layer (B) The lower adhesive strength (3),
When the heat seal resin layer (B) and the heat-sealable adherend are heat sealed, the relationship between the heat seal resin layer (B) and the adhesion force (4) between the adherends is as follows:
(1) <(3) <(2) and (1) <(3) <(4), or (1) '<(3) <(2) and (1)'<(3)<(4) The multilayer sheet having a peeling detection function and a resealing function according to claim 8. The multilayer structure portion (I) includes a transparent or translucent base material layer support (C) and a release layer (D) formed on a part of one side of the base material layer support (C). A colored layer (E) formed on the entire surface or a part of the base material layer support (C) so as to cover the release layer (D),
The said colored layer (E) is laminated | stacked on the said thermoplastic resin layer (X), It has the peeling detection function and resealing function in any one of Claim 2, 3, 4, 5, 6 or 7 Multi-layer sheet. Adhesive force (1) between the base material layer support (C) and the release layer (D),
Adhesive force (1) '' between the release layer (D) and the colored layer (E);
Adhesive force (5) between the base material layer support (C) and the colored layer (E);
The adhesive force (6) between the thermoplastic resin layer (X) and the colored layer (E);
Either the adhesive force between the thermoplastic resin layer (X) and the pressure-sensitive adhesive resin layer (A), or the adhesive force between the pressure-sensitive adhesive resin layer (A) and the heat seal resin layer (B) The lower adhesive strength (3),
When the heat seal resin layer (B) and the heat-sealable adherend are heat sealed, the relationship between the heat seal resin layer (B) and the adherend (4) between the adherend and
(1) <(3) <(4) and (1) <(3) <(5) and (1) <(3) <(6), or (1) ''<(3)<(4) And (1) ''<(3)<(5) and (1) ''<(3)<(6), the multilayer sheet having a peeling detection function and a reseal function. The multilayer structure portion (I) and the multilayer structure portion (II) are laminated via at least one adhesive layer (F). A multilayer sheet having a peeling detection function and a resealing function according to any one of 9, 10 and 11. The multilayer sheet having a peeling detection function and a resealing function according to claim 12, wherein the adhesive layer (F) is a layer containing an acrylic pressure-sensitive adhesive. The multilayer structure part (I) and the multilayer structure part (II) are laminated via a reinforcing layer (G). , 12 or 13, A multilayer sheet having a peeling detection function and a resealing function.

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