JP7127399B2 - Recyclable laminates and recycled packaging materials and packages - Google Patents

Description

TECHNICAL FIELD The present invention relates to a laminate having excellent recyclability. Specifically, the laminate of the present invention is preferably a laminate for packaging materials, and can be remelted and homogenized to become raw materials for new packaging materials. can exhibit sufficient performance as a packaging material.

In the past, packaging materials made of resin were often multi-layered bodies made up of many types of resins. They were inhomogeneous and lacked transparency.

It is not realistic to separate the layers of a multilayer body and combine only compatible resins and remelt them, and the application is very limited for recycling in a heterogeneous or opaque state.

Also, a method has been proposed in which polyester resin recovered from used packaging materials such as PET bottles is made reusable and recycled as recycled polyester for molding packaging materials. Obtaining a recycled film having sufficient impact strength and haze value has not been achieved (see, for example, Patent Documents 1 and 2).

JP 2011-256328 A JP 2012-41463 A

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-described problems in the prior art, and to provide a laminate having a multilayer structure containing a plurality of types of resins, without separating each layer, and the entire laminate is mixed and melted. To obtain a laminate having excellent transparency and excellent recyclability in which the resulting resin is homogeneous even when the remelted resin is homogenous, and furthermore, the remelted resin is used as a homogeneous packaging material having excellent transparency. It is to obtain a package.

In the present invention, the sealant layer and the reinforcing layer each contain different types of resins, but by containing maleic anhydride-modified polyethylene as a compatibilizer, even if the entire laminate is remelted, it will be uniform. A resin having excellent transparency can be obtained at .

The present invention is characterized by the following points.
1. A recyclable laminate having a layer structure having at least a sealant layer and a reinforcing layer,
The recyclable laminate does not contain one or more selected from the group consisting of metal foil, vapor-deposited metal film, and vapor-deposited metal oxide film,
The sealant layer contains linear low density polyethylene and a compatibilizer,
The content of the compatibilizer in the entire sealant layer is 5% by mass or more and 20% by mass or less,
The reinforcing layer contains an ethylene-vinyl alcohol copolymer or a polyamide resin,
The above recyclable laminate, wherein the thickness of the reinforcing layer is 5% or more and 20% or less of the total thickness of the recyclable laminate.
2. 2. The recyclable laminate according to 1 above, wherein the compatibilizer is an unsaturated carboxylic acid-modified polyolefin.
3. 3. The recyclable laminate according to 1 or 2 above, wherein the compatibilizer is maleic anhydride-modified polyethylene.
4. 4. The recyclable laminate according to any one of 1 to 3 above, wherein the sealant layer is laminated on both sides of the reinforcing layer.
5. 5. The recyclable laminate according to any one of 1 to 4 above, further comprising a substrate layer laminated on one side surface of the laminate.
6. A recyclable packaging material produced from the recyclable laminate according to any one of 1 to 5 above.
7. 7. A recyclable package made from the recyclable packaging material according to 6 above.
8. 1 or 2 selected from the group consisting of the recyclable laminate according to any one of 1 to 5 above, the recyclable packaging material according to 6 above, the recyclable packaging material according to 7 above, and the compatibilizer. A recycled resin composition obtained by melt-mixing a mixture containing the above,
The content of the linear low-density polyethylene in the entire recycled resin composition is 50% by mass or more and 90% by mass or less, and the ethylene-vinyl alcohol copolymer or the polyamide resin is 5% by mass or more, 25% by mass or less, and the compatibilizer is 4% by mass or more and 20% by mass or less.
9. 9. A recycled film produced from the recycled resin composition as described in 8 above.
10. 9. A recycled packaging material produced using the recycled film described in 9 above.
11. 11. A recycled package made from the recycled packaging material according to 10 above.

The laminate of the present invention is a laminate having a multilayer structure containing multiple types of resins. It is possible to obtain a laminate having excellent recyclability and excellent recyclability. Furthermore, it is possible to obtain homogeneous and highly transparent packaging materials and packages from the remelted resin.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross-sectional view showing one example of the layer structure of a recyclable laminate of the present invention. FIG. 4 is a schematic cross-sectional view showing another example of the layer structure of the recyclable laminate of the present invention.

The recyclable laminate of the present invention will be described in detail below. The present invention will be described by showing a specific example, but the present invention is not limited to this.

<Recyclable laminate>
The recycled laminate of the present invention has a layer structure having at least a sealant layer and a reinforcing layer, and may further have a base material layer, if necessary. In addition, the recycled laminate of the present invention can contain the compatibilizer in any layer, preferably in the sealant layer.
The recyclable laminate of the present invention can be melt-blended and used as a raw material for a recycled resin composition.
Further, since the recycled laminate of the present invention is melted as a whole and homogenized and made transparent, it is preferable not to have a metal foil, a metal vapor deposition film, a metal oxide vapor deposition film, or the like.

[Compatibilizer]
The compatibilizing agent in the present invention is a component that improves the compatibility of the molten mixture when the recyclable laminate is melted, and produces the effects of homogenization and transparency.
In the present invention, the compatibilizer is preferably contained in the sealant layer, and the content of the compatibilizer in the entire sealant layer is preferably 5% by mass or more and 20% by mass or less.

If the content of the compatibilizer is less than the above range, the compatibilizing effect will not be sufficiently exhibited, and if it is more than the above range, the film strength of the recycled resin obtained by remelting may decrease. .
Specific examples of the compatibilizer depend on the types of resin components constituting the sealant layer and the reinforcing layer, but in the present invention, unsaturated carboxylic acid-modified polyolefin is preferable, and maleic anhydride-modified polyethylene is more preferable.

[Sealant layer]
In the recycled laminate of the present invention, the sealant layer is laminated on the outermost surface of at least one side of the laminate, and may be laminated on both surfaces.
The sealant layer is preferably formed on the reinforcing layer. Alternatively, it may be formed on both sides.
The sealant layer may be composed of one layer or two or more layers. In the case of two or more layers, the layers may have the same composition or may have different compositions.

However, the layer constituting the outermost surface of the sealant layer preferably contains a resin having excellent heat-sealing properties.
The sealant layer exhibits heat-sealing properties by containing a heat-sealing resin.

As specific heat-sealing resins, thermoplastic resins can be used, for example, polyethylene (PE), low-density polyethylene (LDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), linear (linear) low density polyethylene (LLDPE), metallocene polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ionomer resin, ethylene-ethyl (meth)acrylate copolymer, ethylene-(meth)acrylic acid copolymer, Polyolefin resins such as ethylene-propylene copolymer, methylpentene polymer, polyethylene or polypropylene modified with unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, ethylene-(meth) ) Acrylic acid ester-unsaturated carboxylic acid terpolymer resin, cyclic polyolefin resin, cyclic olefin copolymer, polyethylene terephthalate (PET), polyacrylonitrile (PAN), and the like.

among these. The sealant layer preferably contains a polyethylene-based resin, more preferably linear low-density polyethylene (LLDPE), as a heat-sealable resin.
The sealant layer may be a layer laminated by (co)extrusion lamination or a layer laminated by film application.

[Reinforcement layer]
In the present invention, the reinforcing layer is a layer that functions as a support layer for the sealant layer, and is a layer responsible for reinforcing the tensile strength, bending strength, impact strength, puncture strength, breaking strength, toughness, rigidity, etc. of the recycled laminate. .

The reinforcing layer may be composed of one layer or two or more layers. In the case of two or more layers, the layers may have the same composition or may have different compositions.
The resin contained in the reinforcing layer is not particularly limited as long as it can function as a support layer and is easily compatible with the sealant layer, but it preferably contains an ethylene-vinyl alcohol copolymer or a polyamide resin.
The reinforcing layer may be a layer made of a non-stretched, uniaxially stretched or biaxially stretched resin film or resin sheet, or may be formed by co-extrusion lamination with the sealant layer, or may be formed by extrusion lamination on the base layer. It may be a layer laminated by

The thickness of the reinforcing layer is preferably 5% or more and 20% or less of the total thickness of the recyclable laminate.
If the thickness is less than the above range, the barrier properties and film strength are likely to decrease. .

Reinforcing layer, if necessary, has properties such as workability, heat resistance, weather resistance, mechanical properties, dimensional stability, antioxidant properties, lubricity, releasability, flame retardancy, mold resistance, electrical properties, and strength. Add plastic compounds and additives such as lubricants, cross-linking agents, antioxidants, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, and pigments for the purpose of improving and modifying The addition amount can be arbitrarily added according to the purpose within a range that does not adversely affect other performances.

In addition, in order to improve adhesion, the surface of the reinforcing layer or the film or sheet constituting the reinforcing layer may be subjected to corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen gas, nitrogen gas, or the like in advance before lamination. Physical treatment such as treatment, glow discharge treatment, or chemical treatment such as oxidation treatment using chemicals may be performed.

[Base material layer]
The recyclable laminate of the present invention can further have a substrate layer, if desired.
In the present invention, the base material layer functions as a further support layer for the recyclable laminate, or as the outermost layer of the package, includes a printed layer to impart decorativeness, stain resistance and cut resistance. It is a layer that can provide external environment resistance such as.

The substrate layer is preferably laminated on one side surface of the recyclable laminate in order to exhibit its function as a substrate layer.
Materials generally used as base layers can be used for the base layer, but since they are remelted together with other layers to homogenize and become transparent, they can be used as reinforcement layers and sealant layers. It is preferable that the layer is made of a compatible resin.

Specific resins include polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate; polyamide resins such as nylon 6, nylon 66, and MXD6 (polymetaxylylene adipamide); cellophane; polyolefin resins such as polyethylene resins, polypropylene resins and acid-modified polyolefin resins; polystyrene resins; polyurethane resins; acetal resins;

Moreover, it is preferably a uniaxially or biaxially stretched resin film or resin sheet.

The substrate layer may be composed of one layer or two or more layers. In the case of two or more layers, the layers may have the same composition or may have different compositions.

Depending on the type of contents to be packaged and the conditions of use such as the presence or absence of heat treatment after filling, a suitable material can be freely selected and used, but among the above, polyester-based resins and polyamide-based resins are preferable. .

In particular, uniaxially or biaxially oriented polyethylene terephthalate film or sheet, biaxially oriented polypropylene film or sheet, and the like are suitable.

The resin film or resin sheet used for the base material layer has workability, heat resistance, weather resistance, mechanical properties, dimensional stability, oxidation resistance, slipperiness, releasability, flame retardancy, and resistance to heat, if necessary. Addition of lubricants, cross-linking agents, antioxidants, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, etc. to plastics for the purpose of improving mold resistance, electrical properties, strength, etc. Agents, additives, and the like can be added, and the amount added can be arbitrarily added according to the purpose within a range that does not adversely affect other performances.

In addition, in order to improve the adhesiveness, the surface of the substrate layer or the film or sheet constituting the substrate layer is subjected to corona discharge treatment, ozone treatment, oxygen gas, nitrogen gas, or the like in advance before lamination. Physical treatment such as low-temperature plasma treatment and glow discharge treatment, or chemical treatment such as oxidation treatment using chemicals may be performed.

<Recyclable packaging materials>
The recyclable packaging material of the present invention is a packaging material made from the recyclable laminate of the present invention. can also be produced by adding
The recyclable packaging material of the present invention can be melt-mixed and used as a raw material for a recycled resin composition.

<Recyclable packaging>
The recyclable package of the present invention is a package made from the recyclable packaging material of the present invention.
The recyclable package of the present invention can be melt-mixed and used as a raw material for a recycled resin composition.

<Recycled resin composition>
The recycled resin composition of the present invention is obtained by melt mixing a mixture containing one or more selected from the group consisting of recyclable laminates, recyclable packaging materials, recyclable packaging bodies, and compatibilizers. It is a resin composition, and if necessary, various resin components can be added.
It is preferable that linear low-density polyethylene is contained in the entire recycled resin composition in an amount of 50% by mass or more and 90% by mass or less, and an ethylene-vinyl alcohol copolymer or the polyamide resin is contained in an amount of 5% by mass or more. , 25% by mass or less, and the compatibilizer is preferably contained in an amount of 4% by mass or more and 20% by mass or less.
The compatibilizer preferably contains maleic anhydride-modified polyethylene.

<Recycled film>
The recycled film of the present invention is a film produced from the recycled resin composition of the present invention.
The recycled film may be composed of one layer or two or more layers. In the case of two or more layers, the layers may have the same composition or may have different compositions. Also, the layers may be laminated via an adhesive layer.

As a method for producing and laminating a recycled film, for example, one type of recycled resin composition is used, and a film-forming method such as an extrusion method, a cast molding method, a T-die method, a cutting method, or an inflation method is used. A method of film formation, a method of multilayer co-extrusion film formation using two or more recycled resin compositions, a method of mixing two or more recycled resin compositions before film formation and forming a film by the above film-forming method. , a dry lamination method, a sand lamination method, or the like, and film formation, lamination, or film formation and lamination can be performed simultaneously.
Also, when laminating a layer or film made of a resin composition other than the recycled resin composition of the present invention to produce a recycled film, the same method can be used.

<Recycled packaging materials>
The recycled packaging material of the present invention is a packaging material produced using the recycled film of the present invention.
The recycled packaging material may consist of one layer or two or more layers. In the case of two or more layers, the layers may have the same composition or may have different compositions. Also, the layers may be laminated via an adhesive layer.
It is also possible to have layers composed of components other than the recycled film of the present invention.

<Recycled packaging>
The recycled package of the present invention is a package made from the recycled packaging material of the present invention.
For example, the recycled packaging material of the present invention is folded in two, or two sheets of recycled packaging material are prepared, the surfaces of the sealant layers are placed on top of each other, and the peripheral edge is formed, for example, into a standing pouch type, side Seal type, two side seal type, three side seal type, four side seal type, envelope pasted seal type, palm pasted seal type (pillow seal type), pleated seal type, flat bottom seal type, square bottom seal type, gusset type, etc. Various forms of packaging bags can be made by heat-sealing in a sealing form.

Raw materials used in Examples are as follows.
- PET film 1: PET film T4102 manufactured by Toyobo Co., Ltd. 12 µm thick.
LLDPE1: Novatec UF240, MFR 2.1, density 0.920 g/cm ³ , melting point 123°C, manufactured by Japan Polyethylene Corporation.
LLDPE2: Novatec UF320, MFR 0.9, density 0.922 g/cm ³ , melting point 123°C, manufactured by Japan Polyethylene Corporation.
Adhesive 1: Mitsui Chemicals Admer NE827, MFR 5.6, density 0.91 g/cm ³ .
· Maleic anhydride-modified PE1: manufactured by Dow Chemical Co., Ltd., Retain 2000, density 0.912 g/cm ³ .
· Maleic anhydride-modified PE2: manufactured by Dow Chemical Co., Ltd., Retain 3000, density 0.870 g/cm ³ .
EVOH1: EVAL E173B manufactured by Kuraray Co., Ltd., MFR 2.5, density 1.14 g/cm ³ , melting point 165°C).
· Nylon 1: manufactured by Ube Industries, Ltd., 6/12 nylon, density 1.06 g/cm ³ , melting point 136.

[Preparation of resin composition 1 for sealant layer]
The following ingredients were melt-mixed and cooled to obtain a resin composition 1 for a sealant layer.
LLDPE1 90 parts by mass Maleic anhydride-modified PE1 10 parts by mass [Preparation of resin composition 2 for sealant layer]
The following ingredients were melt-mixed and cooled to obtain a resin composition 2 for a sealant layer.
LLDPE2 80 parts by mass Maleic anhydride-modified PE1 20 parts by mass [Preparation of resin composition 3 for sealant layer]
The following ingredients were melt-mixed and cooled to obtain a resin composition 2 for a sealant layer.
LLDPE2 85 parts by mass Maleic anhydride-modified PE1 15 parts by mass

<Preparation and Evaluation of Laminate>
[Example 1]
A laminate consisting of a three-layer film having a thickness of 120 μm and having the following layer structure was produced using a co-extrusion air-cooled inflation film forming machine.
First layer: Resin composition 1 for sealant layer. 50 μm thick.
Second layer: EVOH1. 20 μm thick.
Third layer: Resin composition 1 for sealant layer. 50 μm thick.
The film impact strength and haze value of the obtained three laminates were measured.

[Examples 2 to 3, Production Example 1, Comparative Examples 1 and 2]
According to the layer structure of the laminate shown in Table 1, a laminate was produced in the same manner as in Example 1 and evaluated in the same manner.

[Example 5]
On one side of the three-layer film obtained in Example 1, while extruding the adhesive 1, the PET film 1 was laminated to prepare a laminate composed of a five-layer film with a substrate layer.
Then, it was evaluated in the same manner as in Example 1.

<Preparation and Evaluation of Recycled Film>
[Example 6]
The laminate obtained in Example 1 was melted by a film recycling apparatus, mixed and homogenized, cut while being taken out in the form of a string, and cooled to prepare resin pellets made of a recycled resin composition.
From the resin pellets obtained above, a single-layer recycled film having a thickness of 50 μm was produced using an air-cooled inflation film forming machine.
Then, the film impact strength and haze value of the obtained recycled film were measured.

[Examples 7 to 12, Comparative Examples 3 and 4]
A laminate was selected according to the description in Table 2, and in Examples 9 and 11, maleic anhydride-modified PE2, and LLDPE1 and EVOH1 were added, and the same operation as in Example 6 was performed to produce a recycled film. , was similarly evaluated.

<Summary of evaluation results>
The recyclable laminates of Examples 1 to 3 and 5 of the present invention exhibit good impact strength and haze value, and the recycled films of Examples 6 to 12 produced using these laminates also have excellent impact strength. and the haze value.
However, although the impact strength and haze value of the laminates of Comparative Examples 1 and 2 containing no compatibilizer were good, the recycled films of Comparative Examples 3 and 4 produced using those laminates had poor impact. Intensity and haze values are given.

<Evaluation method>
[Impact strength]
Using a film impact tester with a constant temperature bath manufactured by Toyo Seiki Seisakusho Co., Ltd., the impact strength of the film was measured according to ASTM-D3420.
[Haze value]
It was measured using Haze Guard II manufactured by Toyo Seiki Seisakusho Co., Ltd. in accordance with JIS K7136 and JIS K7361.

1 Recyclable Laminate 2 Reinforcement Layer 3 Sealant Layer 4 Base Layer

Claims (12)

A recyclable laminate having a layer structure having at least a sealant layer and a reinforcing layer,
The recyclable laminate does not contain one or more selected from the group consisting of metal foil, vapor-deposited metal film, and vapor-deposited metal oxide film,
The sealant layer contains linear low density polyethylene and a compatibilizer,
The content of the compatibilizer in the entire sealant layer is 5% by mass or more and 20% by mass or less,
The reinforcing layer contains an ethylene-vinyl alcohol copolymer or a polyamide resin,
The above recyclable laminate, wherein the thickness of the reinforcing layer is 5% or more and 20% or less of the total thickness of the recyclable laminate. The recyclable laminate according to claim 1, wherein the compatibilizer is an unsaturated carboxylic acid-modified polyolefin. The recyclable laminate according to claim 1 or 2, wherein the compatibilizer is maleic anhydride-modified polyethylene. The recyclable laminate according to any one of claims 1 to 3, wherein the sealant layer is laminated on both sides of the reinforcing layer. The recyclable laminate according to any one of claims 1 to 4, further comprising a substrate layer laminated on one side surface of the laminate. A recyclable packaging material made from the recyclable laminate according to any one of claims 1 to 5. A recyclable package made from the recyclable packaging material according to claim 6. One selected from the group consisting of the recyclable laminate according to any one of claims 1 to 5, the recyclable packaging material according to claim 6, and the recyclable package according to claim 7, or A recycled resin composition obtained by melting and mixing two or more kinds,
The content of the linear low-density polyethylene in the entire recycled resin composition is 50% by mass or more and 90% by mass or less, and the ethylene-vinyl alcohol copolymer or the polyamide resin is 5% by mass or more, 25% by mass or less, and the compatibilizer is 4% by mass or more and 20% by mass or less. 1 or 2 selected from the group consisting of the recyclable laminate according to any one of claims 1 to 5, the recyclable packaging material according to claim 6, and the recyclable package according to claim 7 A recycled resin composition obtained by melt-mixing at least seeds and a compatibilizer,
The content of the linear low-density polyethylene in the entire recycled resin composition is 50% by mass or more and 90% by mass or less, and the ethylene-vinyl alcohol copolymer or the polyamide resin is 5% by mass or more, 25% by mass or less, and the compatibilizer is 4% by mass or more and 20% by mass or less. A recycled film produced from the recycled resin composition according to claim 8 or 9 . A recycled packaging material produced using the recycled film according to claim 10 . A recycled package made from the recycled packaging material of claim 11 .

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