JP2012076305A - Laminate and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a packaging material with a barrier property which has an appropriate barrier property and cost performance, while preventing deterioration of appearance, and a method of manufacturing the same.SOLUTION: The laminate includes at least a base material 1 and a barrier layer 3. The barrier layer 3 is formed by 3-kind 5-layer co-extrusion of polyolefin resin 33/adhesive resin 32/ethylene-vinyl alcohol copolymer 31/adhesive resin 32/polyolefin resin 33. The thickness of the layer formed by the ethylene-vinyl alcohol copolymer is 3 to 20 μm. Further, the ethylene copolymerization rate of the ethylene-vinyl alcohol copolymer is 27 to 47 mol%.

Description

  The present invention relates to a packaging material having a function such as a barrier property and a manufacturing method.

Conventionally, as packaging materials with excellent gas barrier properties such as water vapor barrier properties and oxygen barrier properties, laminates containing metal foils and laminates containing plastic films with metal vapor-deposited layers have been formed into bag-like containers and widely used Has been. Aluminum is generally used as the metal from the viewpoint of performance, cost, and workability.
However, the metal foil and the metal vapor-deposited layer are opaque when they have a thickness that exhibits gas barrier properties, and the contents cannot be seen through when used as a packaging material. Further, the metal foil has a problem in disposal property.
On the other hand, resin layers such as ethylene-vinyl alcohol copolymer (hereinafter referred to as EVOH) and polyvinylidene chloride (hereinafter referred to as PVDC) do not have such problems, and the gas barrier properties are slightly inferior to those of metal layers. Since it can be practically used as a barrier material, it is generally used during the construction of a barrier packaging material.
PVDC is used in the form of a film and laminated with other films, or a solution obtained by dissolving PVDC in an appropriate solvent is coated on a base film to form a thin film, and a barrier layer is formed and used. Sometimes.
However, since the above PVDC contains chlorine in its components, it generates chlorine gas when incinerated when discarded after use. In recent years, environmental protection has been screamed, and the specifications of such resins are being shunned.
On the other hand, EVOH hardly permeates fragrance components and is also known as an aroma retaining material. This EVOH is provided as a film having a thickness of 12 to 30 μm, for example, and is laminated with another film by dry lamination using an adhesive or by sand lamination through a layer of molten heat-adhesive resin. It is common to make up part of the material. However, EVOH is an expensive resin, and it is desirable to keep the amount used as low as possible. Further, depending on the package, there is a problem that a component (delamination) occurs in which a component of the package permeates through the laminated body and the adhesive layer is eroded and the laminate part is peeled off.
Therefore, Patent Document 1 proposes a manufacturing method for coextruding a barrier film containing EVOH on a base film, but since EVOH is in the outermost layer of the coextruded film layer, an extruder is used. When forming the film, there were problems such as poor appearance.

Japanese Patent No. 3836164

  The present invention provides a barrier packaging material having an appropriate barrier property, excellent in cost, and relatively unlikely to cause poor appearance, and a method for producing the same.

In order to solve the above problems, a first invention includes at least a base material and a barrier layer, and the barrier layer is a polyolefin resin / adhesive resin / ethylene-vinyl alcohol copolymer / adhesive resin. / A laminated body characterized in that it is formed by coextrusion of three types and five layers of polyolefin-based resin, and the layer thickness of the ethylene-vinyl alcohol copolymer is 3 μm or more and 20 μm or less.
According to a second aspect of the present invention, in addition to the above structure, the ethylene-vinyl alcohol copolymer has an ethylene copolymerization rate of 27 mol% or more and 47 mol% or less.
According to a third aspect of the present invention, in addition to the above structure, the adhesive resin is a polyolefin-based graft polymer, and the carboxyl group concentration is 0.1% by mass or more and 10% by mass or less. .
4th invention is the manufacturing method of the laminated body provided with the base material, the barrier layer, and the sealant layer in this order,
Laminating an anchor layer on one side of the substrate;
Laminating a barrier layer formed by coextrusion of three types of polyolefin resin / adhesive resin / ethylene-vinyl alcohol copolymer / adhesive resin / polyolefin resin on the anchor layer;
Simultaneously with the formation of the barrier layer, a step of sand-laminating a sealant film on the barrier layer to form a sealant layer;
It is a manufacturing method of the laminated body characterized by providing.

According to the present invention, it is possible to maintain the aroma component retention effect while keeping the amount of expensive EVOH resin used low.
In forming a multilayer film including an EVOH layer, the dry lamination method requires at least two steps of lamination with three layers of a base material, a barrier material, and a sealant material, but the coextrusion method laminates in one step. can do. The thickness of the EVOH can be arbitrarily adjusted according to the required level of the barrier.
Furthermore, according to the present invention, it is not necessary to use a so-called adhesive such as an anchoring agent for laminating the barrier material and the sealant material, and the use of the adhesive inside the barrier material can be eliminated. It has the effect of preventing the component from attacking the adhesive and causing problems such as delamination.
Furthermore, by using a polyethylene resin as a material constituting the laminate, the polyethylene resin layer serves as a protective film, and has a function of suppressing barrier deterioration of EVOH due to moisture contained in the package.
By extruding a polyethylene resin layer by coextrusion on the outside of EVOH or adhesive resin that has adhesiveness to metal, EVOH and adhesive resin do not directly touch the wall of the extruder. Therefore, the flow of the molten resin on the wall surface of the extruder is improved, and there is an effect that an appearance defect is hardly caused.

It is sectional drawing explaining the layer structure of the barrier layer which comprises the laminated body of this invention. It is sectional drawing explaining the 1st example of the laminated body of this invention. It is sectional drawing explaining the 2nd example of the laminated body of this invention. It is sectional drawing explaining the 3rd example of the laminated body of this invention. It is sectional drawing explaining the 4th example of the laminated body of this invention. It is sectional drawing explaining the 1st example of the conventional laminated body. It is sectional drawing explaining the 2nd example of the conventional laminated body.

In FIG. 1, the schematic cross section of the barrier layer 3 which comprises the laminated body of this invention is shown. The barrier layer 3 is formed by coextrusion of three types and five layers. A polyolefin layer 33, an adhesive resin layer 32, and an EVOH layer 31 are arranged in this order from the outside.
FIG. 3 is a schematic cross-sectional view showing the configuration of the laminate of the present invention. The manufacturing method of this laminated body 20 is as follows.
After printing the ink 4 on the base material 1, an anchor agent is applied to the printing surface side of the base material 1 to form the anchor layer 2. Then, the barrier layer 3 described above is formed on the anchor layer 2 by coextrusion, and lamination with the base material 1 is performed via the anchor layer 2. At this time, a linear low-density polyethylene film can be laminated as the sealant layer 5 on the barrier layer 3 opposite to the anchor layer 2 (see FIG. 2).
Moreover, the surface of the base material 1 can also be activated by performing a corona treatment or an ozone treatment on the printing surface of the base material 1 instead of applying an anchor agent and forming an anchor layer.

  The substrate 1 is preferably a transparent and heat resistant resin. Further, in order to give the laminate a firmness when the laminate of the present invention is used as a standing pouch substrate, a flexible and hard substrate is preferable. Moreover, since it is assumed that the laminated body of this invention hold | maintains a liquid as a to-be packaged object, it is desired to be strong against the stress from the outside, especially a piercing and tearing. Nylon resin is preferable as the resin that satisfies such characteristics, and a stretched film or an unstretched film can be used, but a biaxially stretched nylon film is particularly preferable. The thickness is preferably 10 μm or more and 30 μm or less, for example, 15 μm.

As the ink 4 printed on the base material 1, an ink having good familiarity with the base material 1 and having light resistance is preferable. For example, gravure ink is preferably used.
Anchor layer 2 formed on the printing surface of substrate 1 is a layer for bonding substrate 1 and a barrier layer formed by coextrusion. Therefore, it is preferable to select according to the compatibility between the base material 1 and the outermost layer of the barrier layer 3, and for example, an anchor coating agent of polyurethane resin can be preferably used. The thickness of the anchor layer 2 is preferably 0.1 μm or more and 3 μm or less, and can be specifically adjusted by the coating amount. For example, at a coating amount of 0.5 g / m ² , the layer thickness is about 0.5 μm. Become.

The barrier layer 3 of the present invention is formed by a five-layer coextrusion process using three types of resins, EVOH, adhesive resin, and polyolefin. The barrier layers thus obtained are a polyolefin layer 33, an adhesive resin layer 32, and an EVOH layer 31 in order from the outside (see FIG. 1).
Co-extrusion is performed by a common co-extruder, for example, at 220 ° C. EVOH, adhesive resin, and low density polyethylene are all preferably close in thermal behavior during extrusion.

The EVOH that can be used for forming the EVOH layer 31 has an ethylene copolymerization rate of 27 mol% or more and 47 mol% or less, and an MFR (melt flow rate) of 1 g / 10 min or more and 9 g / 10 min or less at 190 ° C.
The thickness of the EVOH layer 31 is preferably 3 μm or more and 20 μm or less. If the amount is less than this range, a sufficient scent component retention function cannot be maintained, the thickness of the EVOH layer is uneven, or the alkali or alcohol contained in the package is infiltrated into the anchor layer 2 due to pinholes. The appearance of the glass will be damaged, and delamination will occur. If it is thicker than this range, the other two layers cannot be made sufficiently thick, and the processability as the barrier layer 3 may be impaired.

As the adhesive resin that can be used for forming the adhesive resin layer 32, those having good adhesion to EVOH and low-density polyethylene and having a close MFR are preferable. For example, a polyolefin graft copolymer can be preferably used. When the polyolefin graft copolymer is used, the carboxyl group concentration is preferably 0.1% by mass or more and 10% by mass or less. Further, the MFR (melt flow rate) at 190 ° C. is 0.1 g / 10 min or more and 20 g / 10 min or less.
The thickness of the adhesive resin layer 32 is preferably 1 μm or more and 20 μm or less.

The resin that can be used to form the polyolefin layer 33 is preferably a thermoplastic linear low-density polyethylene, and the MFR (melt flow rate) at 190 ° C. is 0.1 g / 10 min or more and 20 g / 10 min or less. This polyolefin layer alone functions as a sealant layer.
The thickness of the polyolefin layer 33 is preferably 3 μm or more and 100 μm or less.
In addition, the value of MFR used in this specification is based on a test method defined in JIS K7210 using an extrusion plastometer defined in JIS K6760 as a test machine.

Although the laminated body of this invention makes the base material 1 and the barrier layer 3 an essential structure, it is the structure further equipped with the 2nd sealant layer 5 in the surface of the side which has not laminated | stacked the base material 1 of the barrier layer 3. FIG. There may be. The sealant layer 5 becomes an inner side when the laminated body of the present invention is formed into a packaging bag, maintains the shape of the bag by enabling heat fusion, and seals the contents.
As such a sealant layer 5, a film generally used as a heat-sealing sealant can be used. For example, a linear low density polyethylene film is preferable.

  The laminate of the present invention may include a low density polyethylene layer 6 between the anchor layer 2 and the barrier layer 3. By extruding the low density polyethylene layer 6 on the anchor layer in advance, there is an effect of further improving the adhesion between the anchor layer 2 and the barrier layer 3.

  Hereinafter, embodiments of the present invention will be described for understanding of the present invention. The embodiment is an example embodying the present invention, and does not limit the technical scope of the present invention.

[Example 1]
As the substrate 1, printing was performed with a gravure ink 4 on a biaxially stretched nylon film having a thickness of 15 μm. Next, an anchor coating agent of polyurethane resin was applied at a coating amount of 0.5 g / m ² on the printing surface side of the substrate 1 to form the anchor layer 2. Three types and five layers are coextruded by a coextrusion machine between the anchor layer 2 forming surface of the base material 1 thus obtained and a linear low density polyethylene film having a thickness of 80 μm which is the second sealant layer 5. The barrier layer 3 having the structure of polyolefin layer 33 (10 μm) / adhesive resin layer 32 (5 μm) / EVOH layer 31 (10 μm) / adhesive resin layer 32 (5 μm) / polyolefin layer 33 (10 μm) is obtained by extrusion sand lamination. It laminated | stacked and the laminated body 10 of this invention was obtained. The polyolefin layer 33 is MFR7 low density polyethylene, the adhesive resin layer 32 is MFR 5.6 Admer NE827 manufactured by Mitsui Chemicals, and the EVOH layer 31 is MFR1.7 and ethylene copolymerization rate is 32 mol%. Edol F171B manufactured by Kuraray Co., Ltd. was used. The laminate 10 thus obtained is shown in FIG.

[Example 2]
As the substrate 1, printing was performed with a gravure ink 4 on a biaxially stretched nylon film having a thickness of 15 μm. Next, an anchor coating agent of polyurethane resin was applied at a coating amount of 0.5 g / m ² on the printing surface side of the substrate 1 to form the anchor layer 2. Three types and five layers are coextruded on the anchor layer 2 forming surface of the base material 1 thus obtained by a coextrusion machine, and polyolefin layer 33 (20 μm) / adhesive resin layer 32 (5 μm) / EVOH layer 31 (10 μm). ) / Adhesive resin layer 32 (5 μm) / Polyolefin layer 33 (20 μm) was laminated by extrusion lamination to obtain a laminate 20 of the present invention. The resin used for forming the barrier layer 3 is the same as that in Example 1. The laminate 20 thus obtained is shown in FIG.

[Example 3]
A biaxially stretched nylon film having a thickness of 15 μm was printed as the substrate 1 with gravure ink 4. Next, an anchor coating agent of polyurethane resin was applied at a coating amount of 0.5 g / m ² on the printing surface side of the substrate 1 to form the anchor layer 2. A low-density polyethylene layer 6 (15 μm) of MFR7 was laminated by extrusion lamination on the anchor layer forming surface of the base material 1 thus obtained by a single layer extruder. Three types and five layers are co-extruded on the low density polyethylene layer 6 by a co-extruder, and the polyolefin layer 33 (20 μm) / adhesive resin layer 32 (5 μm) / EVOH layer 31 (10 μm) / adhesive resin layer 32. The barrier layer 3 having a configuration of (5 μm) / polyolefin layer 33 (20 μm) was laminated by extrusion lamination to obtain a laminate 30 of the present invention. The resin used for forming the barrier layer 3 is the same as that in Example 1. The laminate 30 thus obtained is shown in FIG.

[Example 4]
A biaxially stretched nylon film having a thickness of 15 μm was printed as the substrate 1 with gravure ink 4. Next, an anchor coating agent of polyurethane resin was applied at a coating amount of 0.5 g / m ² on the printing surface side of the substrate 1 to form the anchor layer 2. A low-density polyethylene layer 6 (15 μm) of MFR7 was laminated by extrusion lamination on the anchor layer forming surface of the base material 1 thus obtained by a single layer extruder. The coextrusion of 3 types and 5 layers is carried out between the surface of the base material 1 thus obtained and the linear sealant film having a thickness of 80 μm which is the second sealant layer 5 by a coextrusion machine. The barrier layer 3 having the structure of polyolefin layer 33 (20 μm) / adhesive resin layer 32 (5 μm) / EVOH layer 31 (10 μm) / adhesive resin layer 32 (5 μm) / polyolefin layer 33 (20 μm) is extruded sand. Lamination was performed to obtain a laminate 40 of the present invention. The resin used for forming the barrier layer 3 is the same as that in Example 1. The laminated body 40 obtained in this way is shown in FIG.

[Comparative Example 1]
A biaxially stretched nylon film having a thickness of 15 μm was printed as the substrate 1 with gravure ink 4. Next, an adhesive of polyurethane resin was applied to the printed surface side of the substrate 1 at an application amount of ² g / m ² to form a polyurethane resin adhesive layer 8. An EVOH film 7 having a thickness of 15 μm is dry-laminated on the surface of the base material 1 on which the polyurethane resin adhesive layer 8 is formed, and the polyurethane resin is again applied to the EVOH film on which the base material 1 is not laminated. The adhesive was applied at an application amount of ² g / m ² to form a polyurethane resin adhesive layer 8. Finally, a linear polyethylene film having a thickness of 80 μm was dry-laminated as a sealant layer 5 on the polyurethane resin adhesive layer 8 to obtain a laminate 50 for comparison. The laminated body 50 obtained in this way is shown in FIG.

[Comparative Example 2]
A biaxially stretched nylon film having a thickness of 15 μm was printed as the substrate 1 with gravure ink 4. Next, an anchor coating agent of polyurethane resin was applied at a coating amount of 0.5 g / m ² on the printing surface side of the substrate 1 to form the anchor layer 2. A low-density polyethylene layer 6 (15 μm) of MI7 was formed by a single-layer extruder between the substrate 1 anchor layer 2 forming surface thus obtained and a linear low-density polyethylene film having a thickness of 80 μm as the sealant layer 5. Extrusion sand lamination was performed to obtain a laminate 60 for comparison. The laminated body 60 obtained in this way is shown in FIG.

The laminates 10 to 60 thus obtained were made into three-side bags, each of which was filled with an alkaline detergent, an acidic detergent, a disinfecting alcohol and a powder bath, and a storage test was conducted in a constant temperature bath at 40 ° C. for 2 months. The components of the contents are shown in Table 1.
As a result, for the acidic detergent, the packaging bag made of the laminates 10 to 40 obtained in Examples 1 to 4 and the packaging bag made of the laminates 50 and 60 obtained in Comparative Examples 1 and 2 are significantly different. Although there was no decrease in laminate strength, delamination occurred in the packaging bag made of the laminate obtained in the comparative example when the items to be packaged were alkaline detergent, disinfecting alcohol and powder bath. In the packaging bag made using the laminate of the present invention, no delamination was observed, and it was shown that there was good content resistance. It was observed that delamination occurred in the polyurethane resin layer 8 inside the EVOH layer (lower side in FIG. 6) in the comparative example 1 and in the anchor layer 2 in the comparative example 2. The results are shown in Table 1.

○：ラミネート強度が初期強度と比較して８０％以上
△：ラミネート強度が初期強度と比較して５０％未満
×：アンカー層でデラミが発生した

○: Laminate strength is 80% or more compared to initial strength Δ: Laminate strength is less than 50% compared to initial strength ×: Delamination occurred in anchor layer

The laminate strength was measured by the following measurement method.
After the production, the laminate as a reference for the initial strength was cut into a strip shape with a width of 15 mm in the flow direction (extrusion) to prepare a sample.
For the laminate after the storage test, the contents are removed from the packaging bag, washed, and then the packaging bag (laminate) is cut into strips with a width of 15 mm in the flow direction (for extrusion) to produce a sample. did.
For any sample, the substrate 1 and the anchor layer 2 were peeled off, and the peel strength was measured by pulling up and down with a Tensilon tensile tester using this as the starting end. The pulling speed is 300 mm / min, and the unit is N / 15 mm.

  It can be widely used for packaging materials that require barrier properties and packaging materials that have high-resistance quality requirements.

DESCRIPTION OF SYMBOLS 1 ... Base material 2 ... Anchor layer 3 ... Barrier layer 31 ... EVOH layer 32 ... Adhesive resin layer 33 ... Polyolefin layer 4 ... Ink 5 ... Sealant layer 6 ... Low density polyethylene layer 7 ... EVOH film 8 ... Polyurethane resin adhesive Layers 10, 20, 30, 40 ... (according to the invention) laminate 50, 60 ... (conventional) laminate

Claims (4)

  Comprising at least a substrate and a barrier layer, wherein the barrier layer is formed by coextrusion of three types of five layers of polyolefin resin / adhesive resin / ethylene-vinyl alcohol copolymer / adhesive resin / polyolefin resin, A layered product having a layer thickness of 3 μm or more and 20 μm or less by an ethylene-vinyl alcohol copolymer.   The laminate according to claim 1, wherein the ethylene-vinyl alcohol copolymer has an ethylene copolymerization rate of 27 mol% or more and 47 mol% or less.   The laminate according to claim 1 or 2, wherein the adhesive resin is a polyolefin-based graft polymer, and the carboxyl group concentration thereof is 0.1 mass% or more and 10 mass% or less. A method for producing a laminate comprising at least a substrate, a barrier layer, and a sealant layer in this order,
Laminating an anchor layer on one side of the substrate;
Laminating a barrier layer formed by coextrusion of three types of polyolefin resin / adhesive resin / ethylene-vinyl alcohol copolymer / adhesive resin / polyolefin resin on the anchor layer;
Simultaneously with the formation of the barrier layer, a step of sand-laminating a sealant film on the barrier layer to form a sealant layer;
The manufacturing method of the laminated body characterized by comprising.

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