WO2016175335A1

WO2016175335A1 - Multilayer sealant film

Info

Publication number: WO2016175335A1
Application number: PCT/JP2016/063689
Authority: WO
Inventors: 知己田島; 直彦倉本
Original assignee: サン・トックス株式会社
Priority date: 2015-04-30
Filing date: 2016-04-26
Publication date: 2016-11-03
Also published as: TW201702076A

Abstract

The purpose of the present invention is to provide a sealant film which can be heat-sealed at a lower temperature, can keep the heat seal strength thereof at a high level regardless of the heat-sealing conditions employed, and can make it possible to produce a lid material that can be opened easily. A polyolefin multilayer sealant film which has a laminate layer (A) having at least one layer that serves as one outermost layer and a heat seal layer (B) that serves as the other outermost layer, and in which the laminate layer (A) side is adhered to a base film upon use. The polyolefin multilayer sealant film is characterized in that the laminate layer (A) is made from a polyolefin resin composition containing a polyethylene resin (A1) and the heat seal layer (B) is made from a polyolefin resin composition containing 10 to 70% by weight of a polyethylene resin (B1), 5 to 15% by weight of a propylene-butene copolymer (B2), 10 to 50% by weight of a modified polyolefin polymer (B3) and 10 to 30% by weight of an adhesiveness-imparting agent (B4).

Description

Multilayer sealant film

The present invention relates to a multilayer sealant film. Specifically, it is a multilayer sealant film that can be thermocompression-bonded to the opening of the polyester sheet molding container, and is easily opened at the boundary between the multilayer sealant film sealant layer or adhesive layer and the opening of the polyester sheet molding container. The present invention relates to a polyolefin-based multilayer sealant film exhibiting properties.

A package that can be sealed by heat sealing is widely used for packaging various products such as food, clothing, and industrial parts. Depending on the contents to be packaged, various materials such as polyolefin resins such as polyethylene and polypropylene, polystyrene resins and polyester resins are used.
In general, such a package is obtained by heating a packaging material in which a base film and a sealant film are laminated so that an adhesive layer of the sealant film is an outermost layer on a container obtained by molding the sheet-like material. A form of crimping and sealing is widely used, and opening is performed by peeling off the packaging material.
The sealing strength of the package is required to be sufficiently strong so that it does not open during transportation, storage, sales, etc., but it must be weak enough for the end consumer to easily open in the above manner. .
The sealant film in the packaging material is a very important member at the time of sealing and opening with the container, but since the materials of the container to be heat-sealed are various, sufficient sealing strength with the container and easy at the time of opening. It was very difficult to satisfy both that opening was possible.
The sealant film has been studied from the viewpoints of heat seal strength, easy opening, and other aspects, and various configurations have been proposed. In Japanese Patent No. 3312951, a composition containing 10 to 40% by weight of an olefinic thermoplastic resin, 15 to 40% by weight of an olefinic elastomer, 5 to 40% by weight of a modified olefinic polymer, and 5 to 30% by weight of a tackifier. A sealant film made of a material has been proposed.
In Japanese Patent No. 3681488, 30 to 95 parts by weight of an ethylene copolymer component obtained by copolymerizing ethylene and an α-olefin in the presence of a single site catalyst, 0 to 55 parts by weight of an olefin (co) polymer component, and a tackifying resin A sealant film consisting of 5 to 30 parts by weight has been proposed.
Packaging materials using these sealant films can be sealed by thermocompression bonding to containers of various materials under appropriate heat seal conditions. It can be easily opened by peeling.
For example, for food business operators who store products in a sealed package for transactions, it is preferable that the container and sealant peel off at the boundary of the sealed package for products that are directly consumed by consumers. Contamination of contents during transportation, storage, and sales of this product must not occur. Therefore, in order to ensure complete heat sealing of the package, heat sealing may be performed under conditions that are more severe than those specified by the packaging material manufacturer.
When heat sealing is performed under conditions of high temperature, high pressure, and long time, the heat sealing strength and / or the content sealing performance may be improved while the opening performance may be significantly impaired for the consumer.
In Patent Nos. 3312951 and 3681488, the heat-sealable temperature range is narrow, and even when thermocompression bonding is performed using appropriate heat-sealing conditions, fluffing occurs at the peeling interface at the time of opening. May fall off, causing foreign matter to be mixed in, or generating a buzzing sound, without a smooth opening, and the contents may jump out of the package.

The present invention has been made to overcome the above-described current situation.
An object of the present invention is to provide a sealant film that can provide a packaging material that can be easily opened, while being capable of heat sealing at a lower temperature and exhibiting high heat seal strength without depending on heat sealing conditions. .
Another object of the present invention is to have a smooth opening property, especially when used as a packaging material for a container formed from a polyester-based sheet, and the dependency of the sealing strength on the heat sealing temperature of 120 ° C to 160 ° C. And providing a polyolefin-based multi-layer sealant film for further providing a content sealing property.
Still other objects and advantages of the present invention will become apparent from the following description.
As a result of intensive studies to achieve the above-described object, the present inventors have found that the interface between the heat seal layer of the polyolefin-based multilayer sealant film and the container is stable even at a heat seal temperature of 120 ° C. to 160 ° C. The present invention has been completed by finding that the peeling mode enables easy and smooth opening regardless of the heat sealing conditions.
That is, according to the present invention, the objects and advantages of the present invention are as follows.
It has a laminate layer (A) consisting of at least one outermost layer and a heat seal layer (B) as the other outermost layer, and the laminate layer (A) side is attached to a base film for use. A polyolefin-based multilayer sealant film for
The laminate layer (A) comprises a polyolefin resin composition containing a polyethylene resin (A1), and
The heat seal layer (B) is 10 to 70% by weight of a polyethylene resin (B1), 5 to 15% by weight of a propylene-butene copolymer (B2), 10 to 50% by weight of a modified polyolefin polymer (B3), And a polyolefin-based multilayer sealant film comprising 10 to 30% by weight of a tackifier (B4) (however, the polyethylene-based resin (B1) in the heat seal layer (B)) The total content of the propylene-butene copolymer (B2), the modified polyolefin polymer (B3), and the tackifier (B4) is 100% by weight.)
Achieved by:
The above objects and advantages of the present invention are secondly,
This is achieved by a packaging material comprising the polyolefin-based multilayer sealant film of the present invention and a substrate film, wherein the polyolefin-based multilayer sealant film is adhered to the substrate film with a laminate layer (A).
Still another object and advantage of the present invention is thirdly,
The opening of the molded container of the polyester sheet containing the contents is achieved by the sealed package body heat-sealed with the heat seal layer (B) of the packaging material by the lid material of the packaging material.

FIG. 1 is a schematic cross-sectional view of the packaging material of the present invention.
FIG. 2 is a schematic cross-sectional view of the sealed package of the present invention.
FIG. 3 is a schematic diagram of a change in strength when the sealed package of the present invention is opened. (Chart image)

DESCRIPTION OF SYMBOLS 1 Polyolefin-type multilayer sealant film 2 Packaging material 3 Base film 4 Contents 5 Container 6 Sealed packaging

Hereinafter, the present invention will be described in detail.
In this specification, the “packaging material” refers to a material used as a lid material for sealing containers and the like obtained by pasting the polyolefin-based multilayer sealant film of the present invention on a base film. The “body” refers to a sealed package obtained by storing the contents in a container or the like and heat-sealing the packaging material.
The “opening strength” in the present invention refers to the maximum strength required when the sealed package is opened from the sealed state, and the “flat portion strength” is the packaging material after the sealed package is opened. This refers to the strength that changes when the material is peeled off.
As described above, the polyolefin-based multilayer sealant film of the present invention is
At least one laminate layer (A) which is the outermost layer;
It has the heat seal layer (B) which is the other outermost layer.
Hereinafter, each layer which comprises the polyolefin-type multilayer sealant film of this invention is demonstrated in detail.
In the present specification, the resin density is a value measured according to ASTM D1505;
The melting point of the resin is the peak top temperature of the peak showing the maximum endotherm in the endothermic curve at the time of temperature rise by a differential scanning calorimeter,
The melt flow rate (MFR) is a value measured at a load of 2.16 kg at the temperature specified below for each resin in accordance with JIS K 6758.
<Laminate layer (A)>
The laminate layer (A) is a layer that is located on the substrate film side and used for adhesion to the substrate film when the polyolefin multilayer sealant film of the present invention is laminated with the substrate film to form a packaging material. is there.
This laminate layer (A) is made of a polyolefin resin composition containing a polyethylene resin (A1).
When the laminate layer (A) is made of the polyolefin resin composition containing the polyethylene resin (A1), it contributes to strong adhesion to the base material and the heat seal layer.
[Polyethylene resin]
The polyethylene-based resin (A1) is a thermoplastic resin obtained by copolymerizing ethylene with a small amount of ethylene and other α-olefins produced by a high pressure method and a low pressure method. Examples of the α-olefin include 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene and the like. The content of the α-olefin unit in the polyethylene resin (A1) is preferably 30 mol% or less, and more preferably in the range of 2 to 20 mol%.
Among these, linear low density polyethylene, which is a copolymer of ethylene and a small amount of other α-olefin, is preferable from the viewpoint of heat resistance when laminated with a base film and adhesion with a heat seal layer. .
The density of the polyethylene resin (A1) is preferably 0.900 to 0.950 g / cm. ³ More preferably, 0.910 to 0.940 g / cm ³ It is. When the density of the polyethylene resin (A1) is too low, blocking of the polyolefin multilayer sealant film is likely to occur. On the other hand, when the density of the polyethylene-based resin (A1) is too high, the polyolefin-based multilayer sealant film may be curled and handling properties may be lowered.
The melting point of the polyethylene resin (A1) is preferably 130 ° C. or lower, more preferably 100 to 130 ° C. When the melting point of the polyethylene resin (A1) is too low, blocking of the polyolefin multilayer sealant film may easily occur. On the other hand, when the melting point of the polyethylene-based resin (A1) is too high, the polyolefin-based multilayer sealant film may be curled and handling properties may be lowered.
The MFR (190 ° C.) of the polyethylene resin (A1) is preferably 0.1 to 50.0 g / 10 minutes, and more preferably 2.0 to 20.0 g / 10 minutes. When the MFR of the polyethylene-based resin (A1) is too low, the viscosity at the time of melting becomes excessively high, so that the resin pressure in the extruder rises during the production of the polyolefin-based multilayer sealant film, and the productivity is remarkably deteriorated. On the other hand, when the MFR of the polyethylene resin (A1) is too high, blocking of the polyolefin multilayer sealant film is likely to occur.
The content of the polyethylene resin (A1) in the laminate layer (A) is from 50 to 100 parts by weight, preferably from 80 to 100 parts, based on 100 parts by weight of the polyolefin resin composition in the laminate layer (A). Parts by weight. When the content of the polyethylene-based resin (A1) is less than 50 parts by weight, the adhesion with the base material and the heat seal layer tends to be lowered, and the function as a packaging material may be impaired.
[Parameter control of resin contained in laminate layer (A)]
The density, melting point, MFR, etc. of the polyethylene resin (A1) can all be controlled by known means. For example, it can be controlled by the production method, catalyst used, comonomer type and copolymerization amount, resin molecular weight, and the like. Moreover, you may select and use the material which has a desired physical property from various commercial items suitably.
[Other resins]
In addition to the polyethylene resin (A1), the laminate layer (A) contains other polyolefin resin composition as long as the adhesiveness between the laminate layer (A), the base film and the heat seal layer is not impaired. You may do it.
Examples of other polyolefin resin compositions include polypropylene resins, polyethylene resins other than the polyethylene resin (A1), and polybutene resins.
[Polypropylene resin]
As said polypropylene resin, the homopolymer of propylene and the copolymer of a propylene and a copolymerization component can be mentioned. As this copolymerization component, for example, an α-olefin having 2 or 4 to 10 carbon atoms is preferable. Specifically, for example, ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1 -Nonene, 1-decene, 4-methyl-1-pentene, etc. can be mentioned, 1 or more types selected from these can be used. The proportion of the copolymer component in this polypropylene resin is preferably 10 mol% or less, more preferably 5 mol% or less, and even more preferably 3 mol% or less.
With respect to the polypropylene resin, the MFR measured with a load of 2.16 kg at 230 ° C. in accordance with JIS K 7210 is preferably 0.5 to 50 g / 10 min.
[Polybutene resin]
Examples of the polybutene-based resin include 1-butene homopolymers and copolymers of 1-butene and other α-olefins. The α-olefin is preferably an α-olefin having 2, 3 or 5 to 10 carbon atoms, specifically, for example, ethylene, propylene, 1-pentene, 1-hexene, 4-methyl-1-pentene. And so on. As a copolymer of 1-butene and another α-olefin, for example, a copolymer of 1-butene and one or more α-olefins selected from the group consisting of ethylene and propylene is preferable.
The content of 1-butene unit in this polybutene resin is preferably 50 to 100 parts by weight, and more preferably 70 to 100 parts by weight, when the total amount of the copolymer is 100 parts by weight.
The density of the polybutene resin is preferably 0.900 to 0.930 g / cm. ³ The MFR (190 ° C.) is preferably 0.1 to 50.0 g / 10 min.
[Other ingredients]
In addition to the resin as described above, the laminate layer (A) can be used as long as it does not impair the function of the layer, for example, petroleum resin, terpene resin, rosin, antiblocking agent, antioxidant, light stabilizer, lubricant, electrification. You may contain other components, such as an inhibitor, an antifogging agent, a coloring agent, a nucleus agent, and an antibacterial agent.
[Production method of laminate layer (A)]
The laminate layer (A) can be obtained by melt-mixing the polyethylene-based resin (A1) and other components used as necessary to form a film. For example, an extruder or the like can be used for the melt mixing, and a T-die or the like can be used for the film formation.
The thickness of the laminate layer (A) is preferably 1.5 to 100 μm. If the laminate layer (A) is too thick, there will be no significant effect on the openability, but it will be inferior in economic efficiency, and if the laminate layer (A) is too thin, the adhesion to the base film and heat seal layer will decrease. There is also a possibility of breaking at the time of opening, which may affect the opening.
<Heat seal layer (B)>
A heat seal layer (B) is a layer which has a function which provides a sealing to the package obtained by thermocompression-bonding the packaging material which laminated | stacked the base film and the sealant film to the container.
This heat seal layer (B) is made of a polyolefin resin, 10 to 70% by weight of a polyethylene resin (B1), 5 to 15% by weight of a propylene-butene copolymer (B2), a modified polyolefin polymer (B3). ) 10 to 50 wt% and tackifier (B4) 10 to 30 wt%.
The contents of the polyethylene resin (B1), the propylene-butene copolymer (B2), the modified polyolefin polymer (B3), and the tackifier (B4) in the heat seal layer (B) are as follows. This is the ratio when the total is 100% by weight.
[Polyethylene resin (B1)]
The polyethylene-based resin (B1) used for the heat seal layer (B) is obtained by copolymerizing ethylene with a small amount of ethylene and other α-olefins, and an ethylene homopolymer produced by a high pressure method and a low pressure method. It is a thermoplastic resin. The α-olefin is preferably an α-olefin having 4 to 8 carbon atoms, and examples thereof include 1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene. The polyethylene-based resin (B1) exhibits an action that contributes to heat resistance when thermocompression bonding with a container or the like and adhesion to the laminate layer. The content of the α-olefin unit in the polyethylene resin (B1) is preferably 30 mol% or less, and more preferably in the range of 2 to 20 mol%.
Among these, the heat resistance when thermocompression bonding with a container or the like, and the adhesiveness with the laminate layer are particularly excellent, so that it is a copolymer of ethylene and a small amount of other α-olefin, linear Low density polyethylene is preferred.
The density of the polyethylene resin (B1) is preferably 0.900 to 0.950 g / cm. ³ More preferably, 0.910 to 0.940 g / cm ³ It is. When the density of the polyethylene resin (B1) is too low, blocking of the polyolefin multilayer sealant film is likely to occur. On the other hand, when the density of the polyethylene resin (B1) is too high, the polyolefin multilayer sealant film may be curled and handling properties may be lowered.
The melting point of the polyethylene resin (B1) is preferably 130 ° C. or less, more preferably 100 to 130 ° C. When the melting point of the polyethylene resin (B1) is too low, blocking of the polyolefin multilayer sealant film may easily occur. On the other hand, when the melting point of the polyethylene resin (B1) is too high, not only thermocompression bonding at a lower temperature becomes difficult, but also the polyolefin multilayer sealant film may curl and handleability may deteriorate.
The MFR (190 ° C.) of the polyethylene resin (B1) is preferably 0.1 to 50.0 g / 10 minutes, and more preferably 2.0 to 20.0 g / 10 minutes. When the MFR of the polyethylene-based resin (B1) is too low, the viscosity at the time of melting becomes excessively high, so that the resin pressure in the extruder increases during the production of the polyolefin-based multilayer sealant film, and the productivity is remarkably deteriorated. On the other hand, when the MFR of the polyethylene resin (B1) is too high, blocking of the polyolefin multilayer sealant film is likely to occur.
The content of the polyethylene resin (B1) used in the heat seal layer (B) is such that the polyethylene resin (B1), the propylene-butene copolymer (B2), and the modified polyolefin heavy in the heat seal layer (B). The amount is 10 to 70% by weight, preferably 15 to 60% by weight, based on 100% by weight in total of the contents of the combined body (B3) and the tackifier (B4). When content of a polyethylene-type resin (B1) is less than 10 weight%, opening strength and flat part intensity | strength become high and are hard to open. When it exceeds 70% by weight, the unsealing strength and the flat portion strength are lowered, and the content sealing performance is poor.
[Propylene-butene copolymer (B2)]
The propylene-butene copolymer (B2) used for the heat seal layer (B) reduces the difference between the maximum strength and the minimum strength of the flat portion strength, and provides smooth opening without generating fuzz or burrs. Shows the effect. The propylene-butene copolymer (B2) has a 1-butene content of preferably 5% by weight or more and less than 40% by weight, more preferably 20% by weight or more and less than 40% by weight, still more preferably 25% by weight or more and 35% by weight. %. These ratios are ratios when the weight of the propylene-butene copolymer (B2) is 100% by weight. When the content of 1-butene of the propylene-butene copolymer (B2) is less than 5% by weight, although there is little influence on the opening strength, the difference between the maximum strength and the minimum strength of the flat portion strength at the time of opening becomes large, A smooth opening feeling cannot be obtained, and if it exceeds 40% by weight, the blocking property may be deteriorated. The melting point of the propylene-butene copolymer (B2) is 140 ° C. or lower, preferably 70 ° C. or higher and 120 ° C. or lower, more preferably 70 ° C. or higher and 100 ° C. or lower. When the melting point exceeds 140 ° C., thermal adhesion at a lower temperature may be impaired. The MFR of the propylene-butene copolymer (B2) is preferably 0.1 to 200 g / 10 min, more preferably 1 to 150 g / 10 min, and further preferably 1 to 20 g / min from the viewpoint of the extrusion characteristics of the resin. 10 min.
The content of the propylene-butene copolymer (B2) used in the heat seal layer (B) is the above-mentioned polyethylene resin (B1), propylene-butene copolymer (B2), and modification in the heat seal layer (B). The content is 5 to 15% by weight, preferably 7 to 12% by weight, based on 100% by weight of the total content of the polyolefin polymer (B3) and the tackifier (B4). When the content of the propylene-butene copolymer (B2) is less than 5% by weight, although there is little influence on the opening strength, the difference between the maximum strength and the minimum strength of the flat portion strength at the time of opening becomes large, and smooth opening When the feeling cannot be obtained and the content exceeds 15% by weight, the opening strength and the flat portion strength are lowered, and the sealing performance of the package is poor.
[Modified polyolefin polymer (B3)]
The modified polyolefin polymer (B3) used for the heat seal layer (B) exhibits an effect of providing adhesion between the heat seal layer and the container. Examples of the modified polyolefin polymer (B3) include copolymers or blends having tertiary hydrogen in the molecule, acrylic acid, methacrylic acid, acrylic acid ester, methacrylic acid ester, acrylic acid metal salt, methacrylic acid. It is a polyolefin-based adhesive polymer obtained by copolymerizing an olefin having a polar group such as an acid metal salt, maleic anhydride, or vinyl acetate. Examples of the polyolefin having tertiary hydrogen in the molecule include atactic polypropylene, isotactic polypropylene, syndiotactic polypropylene, ethylene propylene copolymer, propylene butene copolymer, propylene styrene copolymer, polyisobutene, and ethylene isobutene. Copolymer, poly-4-methylpentene-1, methylpenteneethylene copolymer, propylenemethylpentene copolymer, low density polyethylene, polystyrene, and the like, blends of these tertiary hydrogen-containing polyolefins, these 3 Polyolefins containing tertiary hydrogen and other polymers, ie polymers not containing tertiary hydrogen such as polyolefins, polyesters, polyamides, polyvinyl chloride, polyvinylidene chloride, vinylidene chloride-ethyl acrylate Coalescence, ethylene vinyl alcohol copolymer, polyacrylonitrile, bisphenol A-based polycarbonates, polysiloxanes, cellulose derivatives, ionomers, can be mentioned a blend of such a polyurethane. Among these, a maleic anhydride copolymer using an ethylene-based resin is preferable because the adhesion and adhesion between the container and the packaging material are particularly excellent.
The content of the modified polyolefin polymer (B3) used in the heat seal layer (B) is the above polyethylene resin (B1), propylene-butene copolymer (B2), and modification in the heat seal layer (B). The content is 10 to 50% by weight, preferably 15 to 45% by weight, based on 100% by weight of the total content of the polyolefin polymer (B3) and the tackifier (B4). When the content of the modified polyolefin polymer (B3) is less than 10% by weight, the strength of the flat part is lowered and the sealing property of the package is poor. When the content exceeds 50% by weight, the strength of the flat part is increased and opened. It is difficult to obtain an appropriate opening feeling.
[Tackifier (B4)]
The tackifier (B4) used for the heat seal layer (B) exhibits an action that contributes to improvement in heat sealability at a lower temperature and adhesion due to the interface between the heat seal layer and the container. As the tackifier (B4), a petroleum resin having a softening point of 80 to 150 ° C. is preferable. The petroleum resin is preferably selected from an aliphatic petroleum resin, an aromatic petroleum resin, a copolymer petroleum resin, an alicyclic petroleum resin, a rosin petroleum resin and a terpene petroleum resin. A petroleum-based petroleum resin is particularly preferable. These petroleum resins may be used in a blend of two or more. If the softening point of the petroleum resin is less than 80 ° C., blocking of the polyolefin-based multilayer sealant film may easily occur. On the other hand, if the softening point of the petroleum resin is too high, thermal bonding at a lower temperature tends to be difficult. The softening point of petroleum resin is the softening point measured by the ring and ball method according to JIS K2207.
The content of the tackifier (B4) used in the heat seal layer (B) is such that the polyethylene resin (B1), propylene-butene copolymer (B2), and modified polyolefin heavy in the heat seal layer (B). It is 10 to 30% by weight, preferably 15 to 25% by weight, based on 100% by weight of the total content of the coalesced (B3) and the tackifier (B4). When the content of the tackifier (B4) is less than 10% by weight, the opening strength is lowered and the sealing property of the package is poor. When the content exceeds 30% by weight, there is little influence on the opening strength, but it is flat when opened. The difference between the maximum strength and the minimum strength of the part strength increases, and a smooth opening feeling cannot be obtained.
[Other resins]
In addition to the polyethylene resin (B1), the propylene-butene copolymer (B2), the modified polyolefin polymer (B3), and the tackifier (B4), the resin constituting the heat seal layer (B) In the range which does not impair the adhesiveness with the laminate layer (A), the heat sealability, and the easy-openability, other polyolefin resins may be contained.
Examples of other polyolefin resin compositions include polypropylene resins, polyethylene resins other than polyethylene resins (B1), and polybutene resins.
[Other ingredients]
In addition to the resin as described above, the heat seal layer (B) is an anti-blocking agent, an antioxidant, a light stabilizer, a lubricant, an antistatic agent, an antifogging agent, and a colorant as long as the function of the layer is not impaired. Other components such as an agent, a nucleating agent and an antibacterial agent may be contained.
[Production Method of Heat Seal Layer (B)]
The heat seal layer (B) can be obtained by melt-mixing the above resin and other components used as necessary, and forming into a film. For example, an extruder or the like can be used for the melt mixing, and a T-die or the like can be used for the film formation.
The thickness of the heat seal layer (B) is not particularly limited as long as it does not impair the adhesion to a container or the like, and is preferably about 1.5 to 50 μm, more preferably 2 to 30 μm. If the heat seal layer (B) is too thin, the heat sealability may be insufficient. On the other hand, if the heat-seal layer (B) is too thick, depending on the heat-seal conditions, not only the appearance of the seal part may be deteriorated but the easy-openability may be deteriorated, but also the economy is low, and the resulting packaging material It is not preferable in that the weight of is increased.
<Polyolefin-based multilayer sealant film and method for producing the same>
The polyolefin-based multilayer sealant film of the present invention is constituted by laminating the laminate layer (A) and the heat seal layer (B) in this order. There may be one or more layers as the intermediate layer in addition to the above two layers, and the resin and the like are not particularly limited as long as the adhesion to the laminate layer (A) and the heat seal layer (B) is sufficient. Absent. From the viewpoint of adhesiveness and economy, a resin having performance equivalent to that of the polyethylene resin used for the laminate layer (A) is preferable.
Each layer in the polyolefin-based multilayer sealant film is preferably laminated under non-stretched or low-stretch conditions, and particularly preferably laminated substantially unstretched.
Each layer in the polyolefin-based multilayer sealant film is preferably laminated by a coextrusion method.
As a method for forming each layer, a non-stretching method is preferred. As typical methods, for example, an extrusion molding method using a T die, an inflation molding method using a ring die, and the like can be mentioned, and a feed block method using a T die or a co-extrusion method by a multi-manifold method is particularly suitable. It is.
More specifically, as an extrusion molding method using the T-die, for example,
The resin or resin composition melt constituting each layer is extruded from each extruder by a T-die method, and the extruded melt is
Winding after cooling with a temperature-adjustable roll;
Winding after cooling with a temperature-adjustable water bath;
Winding after cooling by air cooling method; or
Winding after cooling by water cooling method
Can be mentioned.
The polyolefin-based multilayer sealant film obtained by these methods is a low-stretched film or a substantially unstretched film that is slightly stretched by a tension during winding.
The thickness of the polyolefin-based multilayer sealant film of the present invention can be, for example, 3 to 150 μm, and preferably 15 to 120 μm.
The laminate layer (A) and the heat seal layer (B) may be subjected to appropriate surface treatment such as corona discharge treatment or flame treatment prior to lamination for the purpose of improving the adhesion of each layer. There is no restriction | limiting in particular in the surface which performs said surface treatment, Either of single-sided processing and double-sided processing may be sufficient.
<Packaging material>
The polyolefin-based multilayer sealant film of the present invention as described above can be used as a packaging material by sticking to the base film using the surface of the laminate layer (A) as the sticking surface.
FIG. 1 shows a packaging material in which a polyolefin-based multilayer sealant film 1 of the present invention comprising a laminate layer (A) and a heat seal layer (B) is attached to a substrate film 3 with the surface of the laminate layer (A) as the attachment surface. 2 is a schematic cross-sectional view.
The material which comprises a base film can be suitably selected according to the intensity | strength, hardness, etc. which are calculated | required by a packaging material. The base film preferably has, for example, a layer made of one or more resins selected from the group consisting of polypropylene resin, polyethylene resin, polyethylene terephthalate resin and polyamide resin, or a layer made of metal.
Specific examples of the base film include a biaxially stretched polyester film, a biaxially stretched polyamide film, and a biaxially stretched polypropylene film;
Deposition film obtained by depositing metal film on biaxially stretched polyester film, biaxially stretched polyamide film, biaxially stretched polypropylene film, etc .;
Laminated film of biaxially stretched polyester film, biaxially stretched polyamide film, biaxially stretched polypropylene film and other thermoplastic resin films
Etc.
The thickness of the base film can be appropriately set depending on the use of the packaging material, and can be set to about 10 to 300 μm, for example. The base film may be printed with the product name of the contents, the name of the manufacturer, and the like.
The surface of the base film on the side where the polyolefin multilayer sealant film of the present invention is laminated may be subjected to appropriate surface treatment such as corona discharge treatment or flame treatment for the purpose of improving adhesion.
The polyolefin-based multilayer sealant film of the present invention is affixed to a substrate film with the surface of the laminate layer (A) as the affixing surface. As a specific attaching method, for example, a method of placing the polyolefin-based multilayer sealant film of the present invention so that the laminate layer (A) is in contact with one surface of the base film, and thermocompression bonding the both;
A method in which a resin or a resin composition constituting the laminate layer (A) and the heat seal layer (B) is coextruded and laminated on one side of the base film;
Method of sticking one side of base film and surface of laminate layer (A) of polyolefin multilayer sealant film of the present invention with adhesive
Etc.
When the base film and the polyolefin-based multilayer sealant film are thermocompression bonded, the thermocompression bonding temperature is preferably not less than the softening temperature of the laminate layer (A), and the thermocompression bonding pressure is preferably not less than about 0.1 MPa. The thermocompression bonding time is preferably about 0.5 to 5.0 seconds. As the adhesive, for example, a molten resin such as a melted polyethylene resin can be used, and a commercially available adhesive may be used. Examples of the method for applying the adhesive include transfer means such as gravure, gravure reverse, and offset; scraping means such as a bar and a comma bar.
<Sealed package>
The packaging material obtained as described above can be obtained by laminating the heat seal layer (B) in contact with a container or the like and thermocompression bonding. The heat seal temperature is preferably set to a temperature at which the heat seal layer (B) can be thermocompression-bonded, and can be, for example, about 100 to 200 ° C. The heat seal pressure can be set, for example, to about 0.1 to 1.0 MPa, and the heat seal time can be set, for example, to about 0.5 to 5.0 seconds.
The packaging material produced by using the polyolefin-based multilayer sealant film of the present invention can be heat-sealed at a lower temperature, and further forms a sealed package with high heat-seal strength without depending on the heat-sealing conditions. can do.
FIG. 2 is a schematic explanatory view of a hermetically sealed package 6 in which a packaging material 2 composed of a polyolefin-based multilayer sealant film 1 and a base film 3 according to the present invention is sealed by thermocompression bonding with a container 5 containing contents 4. It is shown.
The sealed package can be opened easily and smoothly when the packaging material is peeled off and opened. In addition, since the interface between the heat seal layer and the container is stably peeled off, smooth opening can be achieved without generating fuzz or burrs.
FIG. 3 is a diagram (chart image) schematically showing a change in strength when the packaging material of the sealed package is peeled off and opened.
At the time of opening, the interface between the heat seal layer and the container is peeled off, and the maximum strength when the seal is opened is defined as the opening strength, and then the region where the interface is peeled stably and the strength is stabilized is defined as the flat portion strength.
The smaller the intensity difference in the flat part strength (increase / decrease in strength in a short time), the smoother opening without the occurrence of burrs.
The opening strength of the sealed package can be, for example, 50 N or less, preferably 20 to 50 N, and more preferably 30 to 40 N. The minimum strength of the flat portion strength can be, for example, 10N or less, preferably 3 to 10N, and the difference between the maximum strength and the minimum strength of the flat portion strength can be 3N or less, preferably 1N or less. It can be.
The bursting strength representing the sealing property of the package can be, for example, 20 kPa or more, and preferably 20 to 50 kPa.

Hereinafter, the present invention will be described with reference to examples and comparative examples, but the present invention is not limited to these examples. Each characteristic of the sealed package was measured and evaluated as follows.
(1) Peeling mechanism The container and the packaging material of the sealed package are peeled off with a strong force and opened, and it is visually confirmed that the heat seal layer (B) is not attached to the thermocompressed container side. Judgment was made.
Interfacial exfoliation: Heat seal layer (B) or its aggregates do not adhere to the container side Aggregate exfoliation: Heat seal layer (B) aggregates adhere to the container side, delamination: Heat seal layer (B) or multilayer sealant film (2) Opening strength Prepare a sealed package, cut the container part almost parallel to the packaging material, and separate the chuck and the lid knob part of the packaging material for each chuck of the tensile tester. And pulled in the reverse direction at a pulling speed of 300 mm / min (180 degree peeling), and the maximum strength generated at the initial stage of opening the sealed package was measured. The measurement was performed 10 times, and the average value was defined as the opening strength.
(3) Flat part strength After opening strength measurement, it opened continuously and the area | region where intensity | strength was stabilized was measured. The measurement was performed 10 times, and the average value was defined as the flat portion strength.
(4) Difference between the highest strength and the lowest strength of the flat portion strength The difference between the highest strength and the lowest strength in a region where the strength is stable was measured. The measurement was performed 10 times, and the average value was defined as the difference between the maximum strength and the minimum strength.
(5) Burst Strength Using a burst strength measuring machine (305-BP) manufactured by Sun Science Co., Ltd., 1.0 L / min of air was fed into the container, and the maximum pressure when bursting was measured.
(6) Film tearing at the time of opening The biaxially stretched polyamide film and the dry-laminated packaging material of the sealed package are peeled off with strong force and opened, and the tearing of the packaging material is confirmed visually, and the following judgment is made. It was.
Criteria for judging film tear at opening ○: Good (film was not torn at opening)
X: Defect (the film was torn when opened)
<Resin used>
LLDPE1: Linear low density polyethylene (Ube Maruzen Polyethylene 2040FC, density 0.919 g / cm ³ , melting point 122 ° C., MFR 5 g / 10 min)
LLDPE2: linear low-density polyethylene (Sumitomo Chemical Co., Ltd. CW8003, density 0.912 g / cm ³ , melting point 110 ° C., MFR 8.0 g / 10 min)
LDPE1: Low-density polyethylene (Ube Maruzen Polyethylene Co., Ltd. Z372, density 0.934 g / cm ³ , melting point 118 ° C., MFR 5.0 g / 10 min)
HDPE1: high density polyethylene (HC460R manufactured by Nippon Polyethylene Co., Ltd., density 0.956 g / cm ³ , melting point 132 ° C., MFR 6.5 g / 10 min)
PP1: random copolymer (manufactured by Nippon Polypro Co., Ltd. FW3GT, density 0.890 g / cm ³ melting point 141 ° C., MFR 6.5 g / 10 min)
PP2: Homopolymer (manufactured by Sumitomo Chemical Co., Ltd. FLX80G1, density 0.910 g / cm ³ melting point 161 ° C., MFR 11 g / 10 min)
PB1: Polybutene homopolymer (manufactured by Mitsui Chemicals, Inc., BL4000, density 0.915 g / cm ³ , melting point 112 ° C., MFR 1.8 g / 10 min)
PB2: 1-butenepropylene random copolymer (manufactured by Mitsui Chemicals, Inc., BL2481, density 0.900 g / cm ³ melting point 75 ° C., MFR 4.0 g / 10 min, butene content 79.2 parts by weight)
P-B copolymer 1: Propylene-butene copolymer (Mitsui Chemical Co., Ltd. XM7070, melting point 75 ° C., MFR 7.0 g / 10 min P-B copolymer 2: propylene-butene copolymer (Mitsui Chemicals) XM7080, melting point 83 ° C., MFR 7.0 g / 10 min EP copolymer 1: ethylene-propylene copolymer (P-0180, Mitsui Chemicals, Ltd., melting point 32 ° C., MFR 4.4 g / 10) Minute EP copolymer 2: ethylene-propylene copolymer (P-0280 manufactured by Mitsui Chemicals, Inc., melting point 35 ° C., MFR 3.0 g / 10 min EB copolymer 1: ethylene-butene copolymer (A-1085S manufactured by Mitsui Chemicals, Inc., melting point 69 ° C., MFR 1.2 g / 10 min EB copolymer 2: ethylene-butene copolymer (A-4085S manufactured by Mitsui Chemicals, Inc., melting point 69 ° C., MFR 3.6 g / 10 Reforming PO1: ethylene - butene copolymer (manufactured by Mitsui Chemicals Co., Ltd. model SE 800, density 0.900 g / cm ^3, a Vicat softening point 50 ℃, MFR 4.4g / 10 min)
Modified PO2: ethylene-1-butene copolymer (SF731, manufactured by Mitsui Chemicals, density 0.880 g / cm ³ , Vicat softening point 43 ° C., MFR 6.0 g / 10 min)
Modified PO3: ethylene methyl methacrylate (manufactured by Sumitomo Chemical Co., Ltd. WH401-F, density 0.940 g / cm ³ , Vicat softening point 50 ° C., MFR 20.0 g / 10 min, MMA content 20%)
Tackifier 1: Alicyclic petroleum resin (P-115, Arakawa Chemical Co., Ltd., softening point 115 ° C.)
Tackifier 2: Alicyclic petroleum resin (P-125, Arakawa Chemical Co., Ltd., softening point 125 ° C.)
Example 1
<Manufacture of polyolefin-based multilayer sealant film>
T-die system with three types and three layers, one single screw extruder (EX1 and EX3) for each outer layer with a screw diameter of 50 mm and one single screw extruder (EX2) with a screw diameter of 75 mm for the intermediate layer In the film-forming apparatus, two laminate units (EX1) for the outer layer and EX2 for the intermediate layer (EX2) are used for the laminate layer (A layer), and the heat seal layer (B layer) By using another extruder for the outer layer (EX3), a two-layer film of laminate layer (A) / heat seal layer (B) was obtained. Moreover, resin was supplied to the extruder for each layer as follows.
A layer extruder: LLDPE1 100 parts by weight B layer extruder: LLDPE1 70 parts by weight, PB copolymer 1 5 parts by weight, modified PO 10 parts by weight and tackifier 1 15 parts by weight The above three extrusions In any of the machines, the resin was melted at a resin temperature of 230 ° C. and a residence time of 1 minute, and extruded by a feed block method from each T die with a die lip gap of 1.5 mm under the condition of a T die temperature of 230 ° C. The layers were combined to obtain a multilayer film through a cooling roll at 30 ° C. This multilayer film had a two-layer structure, the total thickness was 30 μm, and the two-layer thickness structure was an A layer of 22 μm and a B layer of 8 μm. Next, after the corona discharge treatment was performed so that the wetting index of the surface on the A layer side of the multilayer film obtained above was 40 mN / m, the laminate layer (A) was wound by a winder / A polyolefin-based multilayer sealant film comprising a heat seal layer (B) was obtained.
<Manufacture of packaging materials>
As a base film, a corona discharge treatment was performed on one side of a biaxially stretched polyamide film (product name “ONM”, thickness 15 μm) manufactured by Unitika Ltd. so that the wetting index was 40 mN / m.
The corona discharge treated surface of this base film and the corona discharge treated surface (laminate layer (A) surface) of the polyolefin multilayer sealant film obtained above were bonded together with an ester adhesive to obtain a packaging material.
Next, using a semi-automatic cup sealer (Aisin Pack Industry Co., Ltd., model name “semi-automatic O-type”), the heat seal layer (B) of the packaging material and a container (A-PET sheet manufactured by Kanebo Co., Ltd.) Thickness 0 2 mm) in a sealed shape having a width of 3 mm, an outer diameter of 92 mm, and an inner diameter of 86 mm, and heat sealed under conditions of a temperature of 120 ° C., a time of 0.8 seconds, and a pressure of 0.4 MPa, to obtain a sealed package.
<Evaluation of sealed package>
The above (1) to (6) were evaluated for the sealed package obtained above.
The evaluation results are shown in Table 1.
Examples 2 to 21 and Comparative Examples 1 to 16
In Example 1 above, the multilayer film and the amount of resin supplied to the extruder for each layer and the thickness of each layer were the same as in Example 1 except that the thickness of each layer was as shown in Tables 1 to 5. Sealed packages were manufactured and each evaluated.
The evaluation results are shown in Tables 1 to 5.

Effects of the Invention The packaging material produced using the polyolefin-based multilayer sealant film of the present invention provides a sealed package that can be easily opened without depending on heat seal conditions. Therefore, by appropriately setting the conditions for heat-sealing the packaging material, it is possible to obtain a hermetic package in which high heat-sealing strength and easy-openability are compatible.
Specifically, in a sealed package in which the packaging material is thermocompression bonded to the container, when the packaging material is peeled off and opened, the interface between the heat seal layer and the container is peeled off at the start of opening, depending on the heat sealing conditions Without fail, reliable easy peel (low opening strength) is demonstrated. In addition, by using a specific amount of the propylene-butene copolymer (B2), the subsequent opening can be stably peeled off at the interface between the heat seal layer and the container, without causing fuzz and crisp sounds. Smooth opening (flat part strength with little difference in strength) is possible.
The packaging material produced using the polyolefin-based multilayer sealant film of the present invention can be heat-sealed at a lower temperature and can be smoothly opened. For example, food and miscellaneous goods such as confectionery, beverages and ice It is extremely suitable as a raw material for packaging materials for sealing and storing and trading.

Claims

It has a laminate layer (A) consisting of at least one outermost layer and a heat seal layer (B) as the other outermost layer, and the laminate layer (A) side is attached to a base film for use. A polyolefin-based multilayer sealant film for
The laminate layer (A) comprises a polyolefin resin composition containing a polyethylene resin (A1), and
The heat seal layer (B) is 10 to 70% by weight of a polyethylene resin (B1), 5 to 15% by weight of a propylene-butene copolymer (B2), 10 to 50% by weight of a modified polyolefin polymer (B3), And a polyolefin-based multilayer sealant film comprising a polyolefin-based resin composition containing 10 to 30% by weight of a tackifier (B4).
(However, the content of the polyethylene resin (B1), the propylene-butene copolymer (B2), the modified polyolefin polymer (B3), and the tackifier (B4) in the heat seal layer (B). The total is 100% by weight.)
The laminate layer (A) has a thickness of 1.5 to 100 μm, the heat seal layer (B) has a thickness of 1.5 to 50 μm, and the laminate layer (A) and the heat seal layer (B) are both The multilayer sealant film according to claim 1, which is laminated by an extrusion method.
A polyolefin multilayer sealant film according to any one of claims 1 to 2 and a substrate film, wherein the polyolefin multilayer sealant film is affixed to the substrate film on the laminate layer (A) side. And packaging material.
The packaging according to claim 3, wherein the base film has a layer made of at least one resin or metal selected from the group consisting of polypropylene resin, polyethylene resin, polyethylene terephthalate resin, and polyamide resin. Wood.
A sealed package body in which an opening of a molded container of a polyester sheet containing the contents is heat-sealed with the heat-sealing layer (B) of the packaging material by the packaging material lid material according to claim 4.
The hermetic package according to claim 5, wherein peeling occurs at the boundary between the heat seal layer and the opening of the container.
The burst strength is 20 to 50 KPa, the opening strength for opening the sealed package is 20 to 50 N, the flat portion strength for opening the sealed package is 2 to 10 N, the highest strength and the lowest strength of the flat portion strength. The sealed package according to claim 6, wherein the difference is 3N or less.