WO2015004980A1

WO2015004980A1 - Coextruded multilayer film

Info

Publication number: WO2015004980A1
Application number: PCT/JP2014/062461
Authority: WO
Inventors: 章晃小野寺
Original assignee: ポリプラスチックス株式会社
Priority date: 2013-07-12
Filing date: 2014-05-09
Publication date: 2015-01-15
Also published as: JP2015016666A

Abstract

　The objective of the present invention is to provide an easy-to-tear coextruded multilayer film that performs as a water-vapor barrier. Provided is a coextruded multilayer film having at least three layers, comprising an intermediate layer containing a cyclic olefin resin and a polyethylene resin, and outer layers containing a polyethylene resin and disposed on both outer sides sandwiching the intermediate layer, wherein the coextruded multilayer film is characterized in that the ratio (B)/(A) is 4 to 8, where (A) is the amount of the cyclic olefin resin contained in the coextruded multilayer film in percentage by mass, and (B) is the amount of the cyclic olefin resin contained in the intermediate layer in percentage by mass.

Description

Multilayer coextrusion film

The present invention relates to a multilayer coextruded film.

In recent years, from the viewpoint of barrier-free, etc., the film used as a packaging material or the like has been required to have a property that is easily tearable by hand (hereinafter referred to as “easy tearability”). Yes. An example of such a film is a film using a cyclic olefin resin, which is a resin having easy tearability, as a material. For example, a multilayer film (Patent Document 1) in which an outer layer and an inner layer containing polyethylene having a specific density and an intermediate layer containing a cyclic olefin-based resin and polyethylene having a specific density are laminated has been proposed.

In addition, as for packaging materials for packaging materials and articles that need to avoid moisture, not only easy tearability but also permeation of water vapor into the packaging materials etc. It may be required to have a property of blocking water (hereinafter referred to as “water vapor barrier property”).

JP 2012-885 A

However, as a result of the study by the present inventors, it was found that the content of the cyclic olefin resin and the distribution of the cyclic olefin resin in the entire film are important for imparting good tearability to the multilayer film. It was. On the other hand, since the multilayer film in Patent Document 1 has not been sufficiently studied about the content and distribution of the cyclic olefin-based resin in the entire multilayer film, it may not have sufficient easy tearability. Moreover, in the multilayer film in patent document 1, nothing is examined about water vapor | steam barrier property.

The present invention has been made to solve the above-described problems, and an object thereof is to provide a multilayer coextruded film having easy tearability and water vapor barrier properties.

The inventor has three or more multilayers composed of an intermediate layer containing a cyclic olefin-based resin and a polyethylene-based resin, and an outer layer disposed on both outer sides of the intermediate layer and containing a polyethylene-based resin. In the co-extruded film, it is found that the above-mentioned problem can be solved by setting the ratio of the content of the cyclic olefin resin in the multilayer co-extruded film and the content of the cyclic olefin resin in the intermediate layer to a predetermined range, The present invention has been completed. Specifically, the present invention provides the following.

(1) an intermediate layer containing a cyclic olefin resin and a polyethylene resin;
An outer layer disposed on both outer sides of the intermediate layer and containing a polyethylene resin;
A multilayer coextruded film of 3 or more layers, comprising:
When the content of the cyclic olefin resin in the multilayer coextruded film is (A) mass% and the content of the cyclic olefin resin in the intermediate layer is (B) mass%,
A multilayer coextruded film, wherein (B) / (A), which is the ratio of (B) to (A), is 4 or more and 8 or less.

(2) The multilayer coextruded film according to (1), wherein the (A) mass% is 5 mass% or more and less than 20%.

(3) The multilayer coextruded film according to (1) or (2), wherein the (B) mass% is 30 mass% or more and less than 95 mass%.

(4) The multilayer copolymer according to any one of (1) to (3), wherein the polyethylene-based resin of the intermediate layer is a mixture of linear low-density polyethylene (LLDPE) and high-pressure method low-density polyethylene (LDPE). Extruded film.

(5) The multilayer coextrusion according to any one of (1) to (4), wherein the polyethylene resin of the outer layer is a mixture of linear low density polyethylene (LLDPE) and high pressure method low density polyethylene (LDPE). the film.

(6) The multilayer coextruded film according to any one of (1) to (5), which is formed by an inflation method having a blow ratio of 1.5 to 4.0.

According to the present invention, a multilayer coextruded film having easy tearability and water vapor barrier properties is provided.

Hereinafter, embodiments of the present invention will be described. In addition, this invention is not limited to the following embodiment.

<Configuration of multilayer coextruded film>
A multilayer coextruded film of the present invention (hereinafter also referred to as “film of the present invention”) is disposed on both outer sides of an intermediate layer containing a cyclic olefin-based resin and a polyethylene-based resin. A multilayer coextruded film of 3 or more layers composed of two outer layers containing a resin.

The film of the present invention is prepared such that the mass ratio of the content of the cyclic olefin resin in the entire film and the content of the cyclic olefin resin in the intermediate layer is within a predetermined range. Specifically, in the film of the present invention, the content of the cyclic olefin resin in the film of the present invention is (A) mass%, and the content of the cyclic olefin resin in the intermediate layer is (B) mass%. In this case, the ratio of (B) to (A), that is, (B) / (A), which is a value obtained by dividing (B) by (A), is adjusted to 4 or more and 8 or less.

The fact that “(B) / (A)” is 4 or more and 8 or less indicates that the thickness of the intermediate layer in the film of the present invention is relatively thin compared to the total thickness of the other layers (outer layers). And the density | concentration of the cyclic olefin resin in an intermediate | middle layer means that it is relatively high compared with the density | concentration of the cyclic olefin resin in another layer. That is, in the film of the present invention, the cyclic olefin-based resin is present at high density in the thin intermediate layer. According to the multilayer coextruded film having such a configuration, the present inventor has excellent easy tearability, and further excellent, even when the total amount of the cyclic olefin-based resin contained in the film is smaller than the conventional amount. It has been found for the first time that a water vapor barrier property can be realized.

When “(B) / (A)” is 4 or more, preferably 4.5 or more, and more preferably 5 or more, sufficient easy tearability and water vapor barrier property can be imparted to the multilayer coextruded film. The higher “(B) / (A)” (especially 7 to 8), the easier it is to obtain a multilayer coextruded film excellent in easy tearing and water vapor barrier properties.

When “(B) / (A)” is 8 or less, preferably 7.5 or less, more preferably 7 or less, the content of the cyclic olefin-based resin in the multilayer coextruded film is not excessive. In addition to not easily damaging the properties of other resins contained in the resin, it is possible to reduce costs. When “(B) / (A)” is more than 8, the difference between the thickness of the intermediate layer and the total thickness of the other layers may increase, and as a result, the resulting multilayer coextruded film Variation in easy tearability and water vapor barrier property. Such variations in easy tearability and water vapor barrier properties are more likely to occur as the intermediate layer becomes thinner (for example, when the thickness of the outer layer: the thickness of the intermediate layer: the thickness of the inner layer = 4: 1: 4). .

“(A) mass%” is not particularly limited as long as the above-mentioned “(B) / (A)” is satisfied, but it is 5% by mass or more and less than 20%, preferably 10% by mass or more and less than 20%, more preferably 5%. It may be from 18% to 18% by mass. According to the present invention, even if the content of the cyclic olefin resin in the film is a small amount of 5% by mass or more and less than 20%, sufficient easy tearability and water vapor barrier property can be imparted to the film. The higher “(A) mass%” (for example, 13 to 17 mass%), the easier it is to obtain a multilayer coextruded film that is particularly excellent in water vapor barrier properties.

“(B) mass%” is not particularly limited as long as the above-mentioned “(B) / (A)” is satisfied, but it is 30% by mass or more and less than 95% by mass, preferably 50% by mass or more and less than 95% by mass, and more preferably. 60 mass% or more and less than 95 mass% may be sufficient. When the content of the cyclic olefin-based resin in the intermediate layer is within such a range, and the polyethylene-based resin is included in the intermediate layer, sufficient easy tearability and water vapor barrier properties can be imparted to the film. When the intermediate layer contains only the cyclic olefin-based resin (that is, when “(B) mass%” is 100 mass%), the obtained film cannot be easily torn, and good easy Does not tear.

The two outer layers arranged on both outer sides of the intermediate layer including the intermediate layer contain a polyethylene resin. The outer layer may be made of a polyethylene-based resin, and may contain a cyclic olefin-based resin as long as the above “(B) / (A)” is satisfied. The two outer layers preferably have the same composition and / or the same thickness in that the curl of the film can be prevented.

(Cyclic olefin resin)
The cyclic olefin resin in the present invention is not particularly limited as long as it is a polymer or copolymer containing a structural unit derived from a cyclic olefin in the main chain. For example, an addition polymer of a cyclic olefin or a hydrogenated product thereof, an addition copolymer of a cyclic olefin and an α-olefin, or a hydrogenated product thereof can be used. A cyclic olefin resin can be used individually by 1 type, or can also use 2 or more types together.

In addition, examples of the cyclic olefin-based resin include those obtained by grafting and / or copolymerizing an unsaturated compound having a polar group in the polymer or the copolymer containing a structural unit derived from a cyclic olefin in the main chain. It is done.

Examples of the polar group include a carboxyl group, an acid anhydride group, an epoxy group, an amide group, an ester group, and a hydroxyl group. Examples of the unsaturated compound having a polar group include (meth) acrylic acid and maleic acid. Acid, maleic anhydride, itaconic anhydride, glycidyl (meth) acrylate, alkyl (meth) acrylate (carbon number 1-10) ester, alkyl maleate (carbon number 1-10) ester, (meth) acrylamide, (meta And 2-hydroxyethyl acrylate.

Further, as the copolymer used as the cyclic olefin resin in the present invention, a commercially available resin can be used. Examples of commercially available cyclic olefin-based resins include TOPAS (registered trademark) (Topas Advanced Polymers), Apel (registered trademark) (Mitsui Chemicals), Zeonex (registered trademark) (manufactured by Nippon Zeon), Examples include ZEONOR (registered trademark) (manufactured by ZEON Corporation), ARTON (registered trademark) (manufactured by JSR Corporation), and the like.

Particularly preferred examples of the addition copolymer of cyclic olefin and α-olefin include [1] a structural unit derived from an α-olefin having 2 to 20 carbon atoms, and [2] represented by the following general formula (I). And a copolymer containing a structural unit derived from a cyclic olefin.

(Wherein R ¹ to R ¹² may be the same or different and are each selected from the group consisting of a hydrogen atom, a halogen atom, and a hydrocarbon group;
R ⁹ and R ¹⁰ , R ¹¹ and R ¹² may be integrated to form a divalent hydrocarbon group,
R ⁹ or R ¹⁰ and R ¹¹ or R ¹² may form a ring with each other.
N represents 0 or a positive integer;
When n is 2 or more, R ⁵ to R ⁸ may be the same or different in each repeating unit. )

[[1] α-olefin having 2 to 20 carbon atoms]
The α-olefin having 2 to 20 carbon atoms is not particularly limited. For example, the same ones as in JP2007-302722 can be mentioned. These α-olefins may be used singly or in combination of two or more. Of these, ethylene is most preferably used alone.

[[2] Cyclic olefin represented by general formula (I)]
The cyclic olefin represented by the general formula (I) will be described. R ¹ to R ¹² in the general formula (I) may be the same or different and are selected from the group consisting of a hydrogen atom, a halogen atom, and a hydrocarbon group. Specific examples of the cyclic olefin represented by the general formula (I) include those similar to those described in JP-A-2007-302722.

These cyclic olefins may be used singly or in combination of two or more. Among these, it is preferable to use bicyclo [2.2.1] hept-2-ene (common name: norbornene) alone.

[1] The polymerization method of the α-olefin having 2 to 20 carbon atoms and the cyclic olefin represented by [2] general formula (I) and the hydrogenation method of the obtained polymer are not particularly limited. Can be carried out according to a known method.

The polymerization catalyst used is not particularly limited, and a cyclic olefin resin can be obtained by a known method using a conventionally known catalyst such as a Ziegler-Natta, metathesis, or metallocene catalyst.

The glass transition point of the cyclic olefin resin is preferably 30 ° C. or higher and 140 ° C. or lower. If the glass transition point of cyclic olefin resin is 30 degreeC or more, it is preferable at the point which can prevent the blocking of the pellets at the time of shaping | molding. If the glass transition point of cyclic olefin resin is 140 degrees C or less, since it is close to the processing temperature of polyethylene resin, it is preferable for the reason that resin blending is easy. The glass transition point of the cyclic olefin resin can be adjusted by adjusting the content of the cyclic olefin skeleton of the main chain. As the glass transition point, a value measured by a DSC method (method described in JIS K7121) under a temperature rising rate of 10 ° C./min is employed.

(Polyethylene resin)
As a polyethylene-type resin in this invention, what is normally used for a film can be used. Examples thereof include linear low density polyethylene (LLDPE), high pressure method low density polyethylene (LDPE) and high density polyethylene (HDPE), ethylene vinyl acetate copolymer (EVA), ethylene ionomer, and polyethylene elastomer. The above resins may be used alone or in combination of two or more. When the above resins are used in combination, the ratio can be appropriately adjusted according to the processability of the film to be obtained.

Of the above resins, LLDPE is preferable in terms of excellent molding stability such as ease of processing. A mixture of LLDPE and LDPE is particularly preferable in that the transparency of the resulting film can be improved in addition to the film forming stability. When a mixture of LLDPE and LDPE is used as the polyethylene resin in the present invention, the mass ratio of these resins may be LLDPE: LDPE = 95: 5 to 60:40.

The polyethylene resin used in the intermediate layer and the outer layer may have the same composition or different compositions. For example, the composition of the polyethylene resin may be different between the intermediate layer and the outer layer, and the polyethylene resins in the two outer layers may be different from each other. In terms of preventing curling of the film, the polyethylene resins used in the two outer layers sandwiching the intermediate layer preferably have the same composition. The polyethylene resin in the intermediate layer and the outer layer preferably have the same composition in that a film having excellent easy tearability and molding stability is obtained, and is a mixture of LLDPE and LDPE having the same composition. Is more preferable.

(Other ingredients)
In the intermediate layer and the outer layer, components usually used as components of the film may be appropriately blended within a range not impairing the object of the present invention. Such components include resins other than cyclic olefin resins and polyethylene resins (polyester resins, etc.), slip agents, antioxidants, secondary antioxidants, colorants, neutralizers, dispersants, light stability Agents, ultraviolet absorbers, lubricants, antistatic agents, antifogging agents, nucleating agents, pigments, colorants, flame retardants, antiblocking agents, and other various organic and inorganic compounds. The blending amount of these components is appropriately adjusted according to the effect to be obtained.

<The manufacturing method of the film of this invention>
The method for producing the film of the present invention is not particularly limited. For example, the film can be produced by a conventionally known extrusion method (T-die multilayer coextrusion method or the like) or an inflation method.

When the film of the present invention is produced by an inflation method, the blow ratio is preferably 1.5 to 4.0. When the blow ratio is within such a range, the stretching effect in the transverse direction (TD direction) perpendicular to the film flow direction is particularly enhanced, which is preferable in that a film having easy tearability can be easily formed.

The composition ratio of the thickness of the intermediate layer in the film of the present invention and the two outer layers disposed on both outer sides of the intermediate layer (hereinafter, the two outer layers sandwiching the intermediate layer are also referred to as “inner layer and outer layer”) There is no particular limitation. However, when “(B) / (A)” is adjusted to the above range, the thickness of the intermediate layer can be reduced as compared with the total thickness of the inner layer and the outer layer. It is preferable that the thickness of the intermediate layer is thinner than the thickness of the inner layer and the thickness of the outer layer in that the effects of the present invention can be easily obtained.

For example, the ratio of the thickness of each layer in the film of the present invention is as follows: outer layer thickness: intermediate layer thickness: inner layer thickness = 3: 1: 3 to 1.5: 1: 1.5 Good. The thickness of the inner layer and the thickness of the outer layer are preferably the same in that the curling of the film can be prevented.

The film of the present invention may have additional layers such as a second intermediate layer and a third intermediate layer in addition to the intermediate layer, the inner layer and the outer layer. That is, the intermediate layer may be composed of a plurality of layers. In such a case, the present invention is prepared by preparing a film so that the total amount of the cyclic olefin-based resin in the intermediate layer composed of a plurality of layers other than the inner layer and the outer layer satisfies the above-mentioned “(B) / (A)”. Film is obtained.

The total layer thickness (that is, the total thickness of the outer layer, the intermediate layer, and the inner layer) of the film of the present invention is not particularly limited. The total thickness of the film of the present invention can be adjusted to, for example, 20 μm or more and 200 μm or less.

<Properties of the film of the present invention>
The film of the present invention is excellent in easy tearability. The easy tearability of the film of the present invention is specified by an Elmendorf tear test according to JIS K7128 and JIS P8116. The lower the obtained value, the lower the tear strength and the better the easy tearability. The film of the present invention is particularly excellent in easy tearability in the transverse direction (TD direction) perpendicular to the film flow direction.

The film of the present invention can be preferably used as various packaging materials (food packaging materials, medical packaging materials, etc.), container lid materials, labels, standing pouches, and the like. Moreover, although the film of this invention can be used individually, the film of this invention can be used as a sealant film, and a well-known base film can also be laminated | stacked on the film of this invention. As a lamination method, a known lamination method such as an extrusion coating method, a hot lamination method, or a dry lamination method can be used.

In addition, the film of the present invention can be preferably used as a three-sided seal packaging material (packaging in which cup noodle ingredients are encapsulated), which is required to have good tearability in the transverse direction perpendicular to the film flow direction. .

The film of the present invention is also excellent in water vapor barrier properties. Therefore, the film of the present invention can be preferably used as a material such as a packaging material for storing substances or articles that need to be stored avoiding moisture such as powder. The water vapor barrier property of the film of the present invention is specified by a moisture permeability test by a cup method according to JIS Z0208. It shows that water vapor | steam barrier property is excellent, so that the value of the obtained water vapor transmission rate is low.

Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these examples.

Using a three-layer inflation molding machine (manufactured by Tommy Machinery Co., Ltd.), a three-layer multilayer coextruded film (total layer thickness: 50 μm) having an intermediate layer, an outer layer and an inner layer sandwiching the intermediate layer was prepared. The molding conditions for the multilayer coextruded film are as follows.

[Molding condition]
A multilayer coextruded film was prepared using a die (die diameter: 106 mm, lip clearance: 2.5 mm) and a screw (φ = 40 mm, L / D = 26). The cylinder temperature of the outer layer and the inner layer of the film was set to 190 ° C., and the cylinder temperature of the intermediate layer of the film was set to 210 ° C. The die temperature was set to 190 ° C., the blow ratio was set to 2.0, and the take-up speed was set to 12.5 m / min.

The intermediate layer of the multilayer coextruded film is composed of a composition in which a cyclic olefin resin is blended with a polyethylene resin in the ratios shown in Tables 1 and 2. The polyethylene resin is composed of LLDPE and LDPE, and the mass ratio thereof is LLDPE: LDPE = 4: 1.

The outer and inner layers of the multilayer coextruded film are made of a polyethylene resin having the same composition as that in the intermediate layer.

In the table, “total COC amount (A)” means the content of the cyclic olefin resin contained in the entire multilayer coextruded film (that is, the cyclic olefin resin contained in the outer layer, the intermediate layer, and the inner layer). Total amount). In addition, the “COC amount (B) of the intermediate layer” indicates the content of the cyclic olefin resin contained in the intermediate layer of the multilayer coextruded film. In the table, “(B) / (A)” is a value obtained by dividing “COC amount of intermediate layer (B)” by “total COC amount (A)”.

The ratio of the thickness of each layer constituting the multilayer coextruded film is as shown in the “layer ratio” in the table (the numerical value indicates “the thickness of the outer layer: the thickness of the intermediate layer: the thickness of the inner layer”). .

Details of the materials used are as follows.
LLDPE: Trade name “Novatech UF230”, manufactured by Nippon Polyethylene Corporation LDPE: Trade name “Novatech LF342M”, manufactured by Nippon Polyethylene Corporation Cyclic olefin resin: Trade name “TOPAS8007F-500”, manufactured by Topas Advanced Polymers

[Measurement of tear strength]
About the multilayer coextrusion film of the said Example and the comparative example, the Elmendorf tear test was done according to JISK7128 and JISP8116, and the tear strength of each multilayer coextrusion film was measured. The results are shown in Tables 1 and 2. In the table, “longitudinal” indicates strength when the multilayer coextruded film is torn in the longitudinal direction (MD direction). Further, “lateral” indicates strength when the multilayer coextruded film is torn in the lateral direction (TD direction). The lower these values, the better the tearability.

[Measurement of moisture permeability]
About the multilayer coextrusion film of the said Example and comparative example, the water vapor permeability test by the cup method was done according to JISZ0208, and the water vapor permeability of each multilayer coextrusion film was measured. The temperature and humidity conditions were set to a temperature of 40 ° C. and a humidity of 90%. The results are shown in Tables 1 and 2. The lower the moisture permeability, the better the water vapor barrier property.

As shown in Tables 1 and 2, when “(B) / (A)” is within the scope of the present invention, a multilayer having low tear strength in both the longitudinal direction and the transverse direction and excellent in easy tearability. A coextruded film is obtained. In particular, the film of the present invention was excellent in easy tearability in the lateral direction. Visually, there was no difference in transparency for any film (data not shown).

Furthermore, as shown in Tables 1 and 2, when “(B) / (A)” is within the scope of the present invention, a multilayer coextruded film having relatively low moisture permeability and excellent water vapor barrier properties can be obtained. . Specifically, when tests with the same value of (A) are compared (for example, Examples 1 and 2 and Comparative Examples 1 and 2), “(B) / (A)” is within the scope of the present invention. For example, it can be seen that a film having low moisture permeability and excellent water vapor barrier properties can be obtained. Moreover, the higher the value of (A), the lower the moisture permeability of the film, and the easier it is to obtain a multilayer coextruded film excellent in water vapor barrier properties.

Claims

An intermediate layer containing a cyclic olefin resin and a polyethylene resin;
An outer layer disposed on both outer sides of the intermediate layer and containing a polyethylene resin;
A multilayer coextruded film of 3 or more layers, comprising:
When the content of the cyclic olefin resin in the multilayer coextruded film is (A) mass% and the content of the cyclic olefin resin in the intermediate layer is (B) mass%,
A multilayer coextruded film, wherein (B) / (A), which is the ratio of (B) to (A), is 4 or more and 8 or less.
The multilayer coextruded film according to claim 1, wherein the (A) mass% is 5 mass% or more and less than 20%.
The multilayer coextruded film according to claim 1 or 2, wherein the (B) mass% is 30 mass% or more and less than 95 mass%.
The multilayer coextruded film according to any one of claims 1 to 3, wherein the polyethylene resin of the intermediate layer is a mixture of linear low density polyethylene (LLDPE) and high pressure method low density polyethylene (LDPE).
The multilayer coextruded film according to any one of claims 1 to 4, wherein the outer layer polyethylene resin is a mixture of linear low density polyethylene (LLDPE) and high pressure low density polyethylene (LDPE).
The multilayer coextruded film according to any one of claims 1 to 5, which is formed by an inflation method having a blow ratio of 1.5 to 4.0.