JP4412430B2 - Single-side absorption deoxygenation multilayer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a film or sheet having a deoxygenating function. More specifically, one-sided absorption used to construct oxygen scavengers or oxygen scavengers with the purpose of preventing the oxidation of various products that are easily affected by the influence of oxygen, such as food, pharmaceuticals and metal products. The present invention relates to a deoxygenated multilayer body.
[0002]
[Prior art]
For the purpose of preventing oxidation of various products that are easily affected by the influence of oxygen, such as foods, pharmaceuticals, and metal products, oxygen scavengers that remove oxygen have been used. The form that was initially developed as the oxygen scavenger and is still widely used is one in which a granular or powder oxygen scavenging composition is packed in a sachet. In order to improve this, a film or sheet having a deoxidized composition fixed thereon is considered as a safe deoxidized substance that is easier to handle, has a wide range of applications, and has no problems such as accidental eating.
[0003]
In order to obtain a film or sheet shape, a method of using a thermoplastic resin as a matrix component and combining it with a granular or powdered deoxygenation composition is simple. However, if this combined film or sheet is used as it is, there is a risk of causing contamination of the content by the deoxidized composition due to contact between the deoxidized body and the content, particularly contact with the liquid. As a countermeasure against this, it is only necessary to cover this single-layer deoxidation layer with another shielding layer or a shielding package. However, in order to take advantage of the characteristics of the film or sheet, the other oxygen-depleting layer is covered with another shielding layer. An ideal configuration is to cover and cover the surface, and an example of such a configuration is disclosed in Japanese Patent Application Laid-Open No. 8-72941. Furthermore, when the oxygen scavenging layer is made porous when stretched and the upper surface is protected by a non-porous layer, a deoxygenating film or sheet having a high oxygen transmission rate and no oxygen scavenger exposure or elution is produced. It is shown in JP-A-9-234811 and JP-A-10-264279 that this can be done.
[0004]
In such a deoxygenating film or sheet, a low oxygen permeable barrier layer that prevents intrusion of oxygen outside the container is generally adhered or fused to the opposite side of the deoxygenating layer. However, due to the deoxidation composition added to the deoxygenation layer, there is a problem in that the adhesion between the deoxygenation layer and the barrier layer is poor. In order to solve this problem, Japanese Patent Application Laid-Open No. 9-234842 and Japanese Patent Application Laid-Open No. 9-40024 propose providing a smoothing resin layer between the deoxidized laminate and the barrier layer. In particular, the film or sheet having a porous oxygen scavenging layer has a problem that the unevenness of the oxygen scavenging layer is remarkably larger than that of the porous film, and it is difficult to improve adhesiveness simply by providing a thermoplastic resin layer. JP-A-9-234811 describes a method of providing a thermoplastic resin layer called a buffer layer between a porous deoxidized layer and a barrier layer.
However, in these methods, the bond strength between the deoxidized layer and the barrier layer may be insufficient, and it is necessary to increase the thickness of the smoothing resin layer or the buffer layer in order to obtain a high bond strength. There is a case. In particular, this problem was remarkable in a film or sheet having a porous oxygen scavenging layer. The problem to be solved by the present invention is to provide a one-side absorption type deoxygenated multilayer body in which the adhesion between the deoxidized layer and the barrier layer is strong.
[0005]
[Means for Solving the Problems]
The inventors have found that the above-mentioned problems can be solved by providing a buffer layer made of a thermoplastic resin between the deoxygenation layer and the barrier layer, and adding a rubber-based additive to the buffer layer, thereby completing the present invention. did. That is, the one-side absorption type deoxygenating film or sheet of the present invention has an oxygen-permeable resin layer (A layer) on one side of a resin layer (C layer) containing a deoxygenating composition, and C In order to improve the adhesion between the E layer and the D layer, a non-porous buffer layer (D layer) and a barrier layer with low oxygen permeability (E layer) are arranged on the other side of the layer. It is characterized by adding a rubber-based additive to the layer. Further, if necessary, a concealing layer (B layer) containing a poorly water-soluble inorganic filler may be provided between the C layer and the A layer, and the C layer or the B layer or both layers may be made porous. Also good.
[0006]
The heat seal layer (A layer) is a layer that is located on the inner surface side of the container and forms a deoxidizing container together with an adjacent layer that uses another heat sealable resin as a matrix component. In order to increase the oxygen absorption rate, the oxygen transmission coefficient is 1 × 10 ^-13 [cm ³ · cm / cm ² · sec · Pa] or more, and further 1 × 10 ^-12 [cm ³ · cm / cm ² · sec · Pa. It is preferable that it is above.
[0007]
The resin constituting the heat seal layer is not limited to a polymer polymerized from a single monomer species, but may be a mixture of various copolymers or resins, and a nonpolar or low-polar polymer is preferable. Furthermore, as long as the oxygen permeability in the entire heat seal layer satisfies the above range, the heat seal layer itself may be composed of a plurality of layers. The heat seal layer is preferably nonporous because the heat seal strength can be kept high. Further, it is preferable to use the same resin as the matrix component of the adjacent layer for the heat seal layer. When different resins are used, they are compatible to the extent that they can be fused together. Thermoplastic resins are preferred.
[0008]
Specific examples of the resin used for the heat seal layer include homopolymers and copolymers of olefins such as ethylene, propylene, 1-butene and 4-methyl-1-pentene, and ethylene-vinyl acetate copolymers. , Polybutadiene, polyisoprene, styrene-butadiene copolymer and its hydrogenated product, various silicone resins, and the like, and further, modified products, grafts, and mixtures thereof may be used. The maximum value of the thickness of the heat seal layer is determined by the required performance of the object to be deoxidized expressed by the oxygen permeability and the oxygen permeability coefficient of the resin. However, if it can be stably manufactured so as not to cause pinholes and it is certain that pinholes and tears will not occur even in contact with the contents during normal use, it is as thin as possible from the maximum value. In general, a thickness of about 5 to 50 μm is preferable.
[0009]
As the deoxidizing composition used for the deoxidizing layer (C layer), known deoxygenating compositions can be used. Among them, metal powders such as iron powder, aluminum powder and silicon powder, and inorganic salts such as ferrous salt A deoxygenating composition containing ascorbic acid and its salts, alcohols such as catechol and glycerin or phenols as a main ingredient is preferable.
The particle size of the oxygen scavenging composition should be smaller than the thickness of the oxygen scavenging layer, and finer in order to increase the oxidation rate and not damage other layers (no penetration). Is desirable. Usually, the maximum particle size is selected from 200 μm or less, more preferably 100 μm or less. The amount of the deoxidizing composition in the C layer is preferably 10 to 60 wt%, and more preferably 30 to 55 wt%.
The deoxygenated layer may be continuously porous by stretching. As the deoxygenation composition to be blended in the deoxygenation layer, a solid deoxygenation composition or a deoxygenation composition in which a liquid deoxygenation composition is supported on an appropriate granular material can be used. In addition, an inorganic filler that is sparingly soluble (including insoluble) in water may be added to the deoxygenated layer as a porosification aid.
[0010]
The concealing layer (B layer) is a layer made of a thermoplastic resin blended with a poorly water-soluble inorganic filler, and is located between the deoxidizing layer (C layer) and the heat seal layer (A layer). It is a layer which hides a layer from the outside. The filler used for the concealing layer (B layer) is not particularly limited as long as it is an inorganic filler that is hardly soluble (including insoluble) in water. Examples of such a filler include silica, alumina, diatomaceous earth, titania, barium sulfate and the like, but it is most preferable to use titania in terms of concealability. Further, when the concealing layer is stretched and made porous, pulverized silica and α-alumina are preferably used from the viewpoint of hardness, handling, and cost, and these are most preferably used in combination with titania. Moreover, since the concealing layer is located between the heat seal layer and the deoxidation layer, it is preferable that the particle size of the filler be as small as possible so as not to penetrate the heat seal layer.
[0011]
As the material constituting the nonporous buffer layer (D layer), the same resin as the resin used for the matrix component of the deoxidation layer or a resin compatible with the resin is used. Homopolymers and copolymers of olefins such as ethylene, propylene, 1-butene, 4-methyl-1-pentene, ethylene-vinyl acetate copolymers, polybutadiene, polyisoprene, styrene-butadiene copolymers and their hydrogen Examples include additives and various silicon resins. Further, these modified products, grafted products, and mixtures may be used.
[0012]
Further, the rubber-based polymer added to the D layer is not particularly limited as long as it can improve the adhesion with the E layer. Specifically, it is a resin having a tensile strength of 40 MPa or less, an elongation at break of 600% or more, and a JISA hardness of 90 or less. Examples of such a rubber-based polymer include styrene butadiene rubber or a hydrogenated product thereof, and acrylonitrile butadiene. Rubber, butyl rubber, chloroprene rubber, butadiene rubber, isoprene rubber, fluorine rubber, silicone rubber, urethane rubber, acrylic rubber, ethylene-α olefin copolymer, ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-butene -Α-olefin copolymer, ethylene-propylene-diene copolymer, styrene-isoprene-styrene copolymer, styrene-butadiene-styrene copolymer, styrene-ethylene-butylene-styrene copolymer, or a mixture thereof Can be illustrated. In particular, when an ethylene-propylene copolymer or an ethylene-1-butene copolymer is added, the adhesive strength is improved. The amount of the rubber-based polymer added is preferably 10 to 90 wt% of the D layer, and more preferably 30 to 70 wt%.
If the thickness of the D layer is thin, the effect of improving adhesiveness cannot be obtained, and if it is thick, the total thickness of the film becomes thick, which is not preferable. The preferred thickness is 5 to 50 μm, more preferably 10 to 30 μm.
[0013]
The resin used for the deoxidation layer and the concealment layer is not particularly limited as long as it can be easily mixed and dispersed with a deoxidation composition such as iron powder and a poorly water-soluble inorganic filler. Rather, it may be selected in consideration of the compatibility with the heat seal layer and the buffer layer, the operating temperature range of the deoxidized multilayer film and sheet, etc. According to the example. The resins used for the A layer, the B layer, the C layer, and the D layer are preferably the same type of resin, and may be different as long as the adjacent layers have compatibility.
[0014]
The barrier layer (E layer) is made of a gas barrier material and functions to prevent oxygen from entering from the outside of the container. Materials constituting the barrier layer (E layer) include polyesters such as polyethylene terephthalate, polyamides such as nylon 6 and nylon MXD6, chlorine-containing resins such as polyvinyl chloride and polyvinylidene chloride, and ethylene-vinyl alcohol copolymers. There are low oxygen-permeable resins such as low-oxygen-permeable resins such as metal foils or metal-deposited resins such as aluminum; and inorganic compound-deposited resins such as silicon oxide.
[0015]
There are various materials other than the above-mentioned materials as long as there are no problems such as the elution rate of deoxygenating films and sheets and the prevention of elution of the deoxygenated composition. It is possible to add other substances. Examples of the additives include pigments and dyes for coloring or hiding, stabilizing components for preventing oxidation and decomposition, antistatic components, moisture absorbing components, deodorizing components, plasticizing components, flame retardant components, etc. Is mentioned. Similarly, layers such as a print layer, an easy-open layer, and an easy-release layer can be added as long as the performance as a deoxygenating film and sheet is not adversely affected.
[0016]
In laminating each layer constituting the present invention, a known laminating method such as ordinary coextrusion, extrusion coating, or extrusion laminating can be used.
The continuously porous resin layer refers to a resin layer having a plurality of voids and continuous voids so that the voids communicate with each other and penetrate the resin layer. Various methods can be adopted as the method, but it is also suitable from the viewpoint of productivity to stretch the resin layer containing the deoxidizing composition and the resin layer containing the poorly water-soluble inorganic filler.
[0017]
In stretching, as is generally known, any method of uniaxial stretching, biaxial simultaneous stretching, and biaxial sequential stretching may be used. Alternatively, a deoxidation layer or a concealing layer filled with a poorly water-soluble inorganic filler or both of them may be stretched, and then each layer may be laminated by adhesion, fusion, vapor deposition or the like. Or in the case of a resinous barrier layer, it may be stretched after laminating from the heat seal layer to the barrier layer. The draw ratio is preferably 2 to 20 times.
[0018]
When a low oxygen-permeable barrier layer is added later, the layer can be bonded or fused by a usual method such as thermal lamination, dry lamination, extrusion coating, or the like, to obtain a final multilayer structure.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
The deoxygenating film and sheet of the present invention have a gas barrier property on one side and a deoxygenating packaging material that can absorb oxygen on the other side. And all in various forms. For example, it can be used for a top seal film of a packaging container or a packaging bag. The contents can be not only solid but also liquid or a mixture of solid and liquid.
[0020]
【Example】
EXAMPLES Hereinafter, although this invention is demonstrated further in detail using an Example and a comparative example, this invention is not limited by this.
[0021]
Example 1
Deoxygenated composition coated with sprayed aqueous solution containing 2 parts by weight of calcium chloride to 100 parts by weight of iron powder having a maximum particle size of about 50 μm and heated and dried, and polypropylene (FW3E manufactured by Nippon Polychem Co., Ltd. After dry blending at a rate of 7.0 g / 10 min), the mixture was kneaded with a 30 mm diameter twin screw extruder, extruded from a strand die, cooled, and cut with a pelletizer to obtain pellets of a deoxidizing resin composition. The composition of the deoxidizing resin composition is 50% by weight of the deoxidizing composition and 50% by weight of polypropylene.
[0022]
After dry blending titania and polypropylene (FW3E manufactured by Nippon Polychem Co., Ltd., melt flow rate 7.0 g / 10 min) as a poorly water-soluble inorganic filler, kneading with a 30 mm diameter twin screw extruder, extrusion from a strand die, and cooling The pellet was cut with a pelletizer to obtain a white resin composition pellet. The composition of the white resin composition is 10% by weight of titania and 90% by weight of polypropylene.
[0023]
A 1: 1 weight ratio mixture of polypropylene (FW3E manufactured by Nippon Polychem Co., Ltd., melt flow rate 7.0 g / 10 min) and ethylene-hydrogenated butadiene rubber (1320P manufactured by JSR Corporation) as the heat seal layer, and the white color as the concealment layer Resin composition, deoxygenating resin composition as deoxidizing layer, and polypropylene (FW3E manufactured by Nippon Polychem Co., Ltd., melt flow rate 7.0 g / 10 min) and ethylene-propylene copolymer (manufactured by Mitsui Chemicals, Inc.) as buffer layer A total of 4 layers of a 1: 1 mixture by weight ratio of P0680) were laminated by coextrusion to obtain a laminate comprising 4 layers. The thickness of each layer of the laminate was 50 μm heat seal layer / 50 μm concealment layer / 100 μm deoxygenation layer / 50 μm buffer layer. Next, an aluminum foil is bonded to the buffer layer as a barrier layer by dry lamination using a urethane-based adhesive (A-515, Takeda Pharmaceutical Co., Ltd., curing agent is A-50, mixing ratio 10: 1), A deoxygenated multilayer film was obtained.
[0024]
The deoxidized multilayer film was cut out to a width of 15 mm, peeled between the buffer layer and the barrier layer, and the laminate strength was measured by a T-type peel test using an autograph (AG-5000B, manufactured by Shimadzu Corporation). The laminate strength was 1.62 kgf / 15mm.
[0025]
Example 2
A deoxygenating resin composition pellet was prepared in the same manner as in Example 1 except that linear low density polyethylene (SP2040 manufactured by Mitsui Chemicals, Inc., melt flow rate 4.0 g / 10 min) was used instead of polypropylene. Example except that silica (average particle size 5 μm) was used as the poorly water-soluble inorganic filler, and linear low density polyethylene (SP2040 manufactured by Mitsui Chemicals, Inc., melt flow rate 4.0 g / 10 min) was used as the thermoplastic resin. In the same manner as in Example 1, white resin composition pellets were obtained. The white resin composition is composed of 50 wt% silica and 50 wt% polypropylene.
[0026]
The same linear low density polyethylene as the deoxygenated layer is used as the heat seal layer, mixed with ethylene-1-butene copolymer (EBM2041P manufactured by JSR Corporation) at a weight ratio of 1: 1, and the white resin as the concealing layer. Using the above-mentioned deoxidizing resin composition as a composition and deoxidizing layer, a linear low density polyethylene (SP2040 manufactured by Mitsui Chemicals, Inc.) and ethylene-1-butene having the same structure as the heat seal layer as a buffer layer A total of 4 layers of a 1: 1 mixture by weight of a polymer (2041P manufactured by JSR Corporation) were laminated by coextrusion to obtain a laminate composed of 4 layers, and then stretched 4 times in a uniaxial direction. The thickness of each layer of this laminate was 20 μm for heat seal layer / 40 μm for concealment layer / 50 μm for deoxygenation layer / 10 μm for buffer layer. Furthermore, an aluminum foil was bonded to this buffer layer as a barrier layer by dry lamination using urethane adhesive (AD-585 manufactured by Toyo Morton, curing agent CAT-10, mixing ratio 10: 1), and a deoxygenated multilayer film was formed. Obtained.
[0027]
The deoxidized multilayer film was cut out to a width of 15 mm, peeled between the buffer layer and the barrier layer, and the laminate strength was measured by a T-type peel test using an autograph (AG-5000B, manufactured by Shimadzu Corporation). The laminate strength was 1.46 kgf / 15mm.
[0028]
Example 3
A deoxygenated multilayer film was obtained in the same manner as in Example 2 except that the composition of the buffer layer was 50 wt% linear low density polyethylene and 50 wt% ethylene-propylene copolymer (P0680 manufactured by Mitsui Chemicals, Inc.). It was. The laminate strength of the obtained deoxidized multilayer film was measured and found to be 1.11 kgf / 15 mm.
[0029]
Comparative Example 1
The composition of the buffer layer was the same as that of Example 1 except that the additive-free polypropylene was 100 wt%. The laminate strength of the obtained deoxidized multilayer film was measured and found to be 0.80 kgf / 15 mm.
[0030]
Comparative Example 2
The composition of the buffer layer was the same as in Example 2 except that the linear polyethylene containing no additive was 100 wt%. The laminate strength of the obtained deoxidized multilayer film was measured and found to be 0.68 kgf / 15 mm.
[0031]
【The invention's effect】
The deoxygenating film and sheet are generally composed of a gas barrier film having one side having oxygen absorbing ability and the other side having low oxygen permeability. Therefore, a laminate of a deoxidizing film and a barrier film is indispensable, and the film performance is greatly influenced by the laminate strength. The present invention relates to an improvement in laminate strength between a deoxygenated multilayer film and a barrier film, and has the effect of greatly improving the performance of a deoxygenating film.
[0032]
ADVANTAGE OF THE INVENTION According to this invention, since the joining strength of a deoxidation layer and a barrier layer improves and high adhesive strength is obtained, the one side absorption type deoxidation multilayer body with a strong joining force between layers is provided. Therefore, it is not necessary to increase the thickness of the smoothing resin layer or the buffer layer or the thickness of the entire multilayer body. In particular, in a film or sheet having a porous oxygen scavenging layer, the effect of improving the bonding strength between the oxygen scavenging layer and the barrier layer is remarkable.

Claims (5)

A continuous porous deoxygenated layer (C layer) made of a thermoplastic resin containing a deoxygenated composition, and a heat seal layer (A) made of an oxygen-permeable thermoplastic resin on one side of the C layer Layer), and the other side of the C layer is composed of a buffer layer (D layer) having a thickness of 10 to 30 μm made of a nonporous thermoplastic resin to which a rubber-based polymer is added and a gas barrier material. A one-side absorption type deoxygenated multilayer body in which barrier layers (E layers) are arranged in this order, wherein the addition amount of the rubber-based polymer is 30 to 70 wt% of the D layer . The multilayer according to claim 1, wherein a concealing layer (B layer) made of a thermoplastic resin blended with a poorly water-soluble inorganic filler is disposed between the deoxidized layer (C layer) and the heat seal layer (A layer). body. The multilayer body according to claim 1, wherein the rubber-based polymer added to the buffer layer (D layer) is an ethylene-propylene copolymer or an ethylene-1-butene copolymer. The multilayer body according to claim 2, wherein the concealing layer (B layer) comprises a continuous porous resin composition. The multilayer body according to claim 1 or 4, wherein the deoxidation layer (C layer) or the concealing layer (B layer) is a continuous porous resin layer stretched 2 to 20 times.