WO2002064367A1

WO2002064367A1 - Multi-layered film and packaging material comprising the same

Info

Publication number: WO2002064367A1
Application number: PCT/JP2002/001201
Authority: WO
Inventors: Kazuyuki Watanabe; Takao Nasu
Original assignee: Showa Denko Plastic Products Co., Ltd.
Priority date: 2001-02-14
Filing date: 2002-02-13
Publication date: 2002-08-22

Abstract

One object of the present invention is to provide a multi-layered film which is used suitably for a food packaging material or a medical packaging material; in order to achieve the object, the present invention provides a multi-layered film comprising: a resincomposition layer (A) containing (a) propylene-α-olefin random copolymers, (b) butene resins, and (c) high-density polyethylenes and/or linear low-density polyethylenes; and a propylene resin layer (B) containing (d) propylene resins.

Description

DESCRIPTION

MULTI-LAYERED FILM AND PACKAGING MATERIAL COMPRISING

THE SAME

TECHNICAL FIELD The present invention relates to a multi-layered film, a sealant film, a laminated material, a packaging material, which exhibit excellent openability, good clouding property (the "clouding" as used herein means the "whitening"), high moisture barrier property and superior low-temperature heat sealability, and which are suitable as a medical packaging material or a food packaging material, and also relates to a medical instrument comprising the same, and the manufacturing methods thereof.

BACKGROUND ART

Heretofore, polyolefin film is used to package various foods or medical instruments by making use of its characteristic features such as inexpensivenss, resistance against heat or chemicals and easy heat sealability.

In the food packaging material, an aluminum foil, a saponified product of ethylene-vinyl acetate copolymer resin and vinylidene chloride resin are used as a gas barrier layer, the gas barrier layer is combined with a polyamide resin layer, a polyester resin layer and the like, and a polyolefin-base resin such as polypropylene or polyethylene is used as a heat seal layer. Also in the medical packaging material, a polyolefin-base resin is used as a heat seal layer.

With respect to the easily openable sealant film, a method of using a resin composition obtained by mixing polypropylene and polyethylene for the sealant layer, and a method of using a resin obtained by graft-polymerizing styrene to a polyolefin-base resin are known.

In the sealant film used for a packaging material which is produced through knurl-sealing, such as a packaging material for a blood sugar measuring electrode, a resin composition obtained by mixing a linear low-density polyethylene with a low melting point polypropylene has been heretofore used for the sealant layer and thereon, a homopolypropylene as a substrate layer is laminated.

The sealant film is characterized in that when the packaging material is opened, the heat sealed portion is clouded ("the heat sealed portion is clouded" as used herein means that the heat sealed portion is whitened) and therefore, it can be confirmed that the packaging material was infallibly heat sealed.

However, the sealant film has a problem in that since the heat seal strength is as high as 11.8 N/15 mm width or more, opening is difficult; since the latitude of the heat seal temperature is narrow, the knurl-sealing machine fails in controlling the temperature; or when the heat seal pressure fluctuates, homopolypropylenes are heat sealed with each other and opening cannot be attained.

Examples of the easily openable sealant film include a packaging material having a heat sealable resin layer which comprises a resin composition layer having a thickness of 5 to 25 μm and containing a crystalline polypropylene-base resin having a melt index of 2 to 100 (g 10 min) and a polyethylene having a melt index of 2 to 50 (g/10 min) in a weight ratio of 50:50 to 95:5 (see, JP-A-58-1672 (the term "JP-A" as used herein means an "unexamined published Japanese patent application")), a container comprising a film layer formed of a blend material of a base resin comprising a crystalline polypropylene or a crystalline propylene-ethylene copolymer with from 8 to 30% by mass of an ethylene-vinyl acetate copolymer having a vinyl acetate content of 8 to 5% by mass, where the heat seal strength after the thermal sterilization is 100 to 1,700 g/cm (see, JP-A-57-28777), and a composite film comprising a propylene-base resin layer and a resin composition layer containing a propylene-ethylene random copolymer and/or a propylene-ethylene-butene-1 ternary copolymer, and a high-pressure polyethylene and/or a linear low-density polyethylene (see, JP-A-63-179741).

These sealant films have a problem in that the low-temperature heat sealability is inferior, the opening strength is too strong or the heat seal portion shows poor clouding or is not clouded at all at the time of opening.

Examples of a combination of a polyethylene and a polybutene-1 include a method of blending a polyethylene and a polybutene-1 for preventing distortion and cracking of a polyethylene-made bottle, pipe, electric wire coating or the like due to contact with a viscous liquid (see, JP-B-39-22351 (the term "JP-B" as used herein means as an "examined Japanese patent publication")).

The combination between propylene resins and butene polymers is disclosed, for example, in Saishin Laminate Kako Binran (Newest Lamination Processing Handbook), page 865 (1989), Kako Gijutsu Kenkyu Kai. Specifically, the document discloses that when 50% by mass of polybutene-1 having a melting temperature 71 ^*C or 75°C is blended with 50% by mass of polypropylene, low-temperature heat sealability are improved.

In addition, JP-A-50-14741 discloses thermoplastic films having excellent low-temperature heat sealability and optical properties, which comprise 80 to 90% by mass of polypropylene and 10 to 20% by mass of polybutene-1.

In addition, JP-B-46-32747 discloses resin compositions having improved low-temperature impact strength, which comprise 30 to 90% by mass of polypropylene, 1 to 69% by mass of polybutene-1, 0.3 to 9% by mass of polyisobutylene, chlorosulfonated polyethylene, saturated silicone rubber, amorphous ethylene/propylene or ethylene/butene- 1.

Furthermore, JP-A-54-48845 discloses polyolefin compositions having improved transparency and anti-clouding property, which comprise 50 to 95% by mass of polypropylene, 5 to 50% by mass of propylene-1-butene random copolymer.

However, this publication neither discloses nor suggests the object of the present invention or the method for solving the problems described in the present invention.

In addition, in a conventional sealant film comprising a sealant layer containing mainly a propylene QJ -olefin random copolymer, heat seal strength strongly depends on heat seal temperature. Specifically, when the heat seal temperature is lόO'C (which corresponds to a melting temperature of homopolypropylene) or less, in particular, less than 140°C, the heat seal strength rapidly deteriorates, and practical openability cannot be obtained. In order to prepare stably a packaging material having practical openability, it is necessary to adjust the heat seal temperature into about 160°C.

Therefore, an object of the present invention is to provide a multi-layered film which is used suitably for a food packaging material or a medical packaging material.

Another object of the present invention is to provide a manufacturing method which is suitably used for manufacturing the multi-layered film.

Another object of the present invention is to provide a multi-layered film, a sealant film, a laminated material, and a packaging material, which have an excellent openability, excellent low-temperature heat sealability, that is, excellent stability of heat seal strength, and a high moisture barrier property. In particular, another object of the present invention is to provide a sealant film which has an improved low-temperature heat sealability. In other words, the sealant film has sufficient heat seal strength to exhibit excellent openability in a range from 140 to lόO'C . Moreover, another object of the present invention is to provide a sealant film which can provide a packaging material having a stable heat seal strength when heat seal temperature varies, compared with a conventional sealant film.

Another object of the present invention is to provide a multi-layered film, a sealant film, a laminated material, and a packaging material, which have a good clouding property and a good appearance without an exhibiting feathering phenomenon.

Another object of the present invention is to provide a manufacturing method which is suitably used for manufacturing the packaging material.

Another object of the present invention is to provide a medical instrument having excellent properties, such as a high moisture barrier property.

DISCLOSURE OF INVENTION

As a result of extensive investigations, the present inventors have found that the above-described object can be attained by stacking a specific resin composition layer and a polypropylene resin layer. The present invention has been realized based on this finding.

In order to achieve the object, the present invention provides a multi-layered film comprising a resin composition layer (A) containing (a) propylene- a -olefin random copolymers, (b) butene resins, and (c) high-density polyethylenes and/or linear low-density polyethylenes; and a propylene resin layer (B) containing (d) propylene resins.

In the multi-layered film, it is preferable for the blend ratio between the components (a), (b), and (c) to be 50 to 80% by mass of the component (a), 10 to 40% by mass of the component (b), and 5 to 20% by mass of the component (c)

In the multi-layered film, it is preferable for the propylene- a -olefin random copolymers to be ethylene-propylene random copolymers containing 3 to 10% by mass of ethylene.

In the multi-layered film, it is preferable for the butene resins to be polybutene-1.

In the multi-layered film, it is preferable for the polybutene-1 to have 0.5 to 15 g/min of a melt flow rate according to ASTM D1238E and 100 to 14CC of a melting temperature according to JIS K 7121.

In the multi-layered film, it is also preferable for the high-density polyethylene to have 0.945 to 0.970 g/cm³ of a density according to JIS K 7112D and 2 to 25 g/10 min of a melt flow rate according to JIS K 7210.

In the multi-layered film, it is preferable for the linear low-density polyethylene to have 0.920 to 0.935 g/cm³ of a density according to JIS K 7112D and 1 to 10 g/10 min of a melt flow rate according to JIS K 7210.

Furthermore, in the multi-layered film, it is also preferable for the propylene resin to be propylene homopolymer.

In addition, in order to achieve the object, the present invention provides a manufacturing method for the multi-layered film comprising the steps of: in a co-extrusion T-die casting method, forming a film at 160 to 250°C, which comprises a resin composition layer (A) comprising (a) propylene- a -olefin random copolymers, (b) butene resins, and (c) high-density polyethylenes and/or linear low-density polyethylenes; and a propylene resin layer (B) comprising (d) propylene resins; and cooling it to 40 to 80^ .

In addition, in order to achieve the object, the present invention provides a sealant film which comprises the multi-layered film, and uses the resin composition layer (A) as a sealant layer.

In the sealant film, it is preferable for a total thickness of the resin composition layer (A) that serves as a sealant layer and the propylene resin layer (B) to be in a range from 20 to 701± m, and for a thickness ratio between the resin composition layer (A) that serves as a sealant layer and the propylene resin layer (B) (layer (A): layer (B)) to be in a range from 0.05~0.3: 0.95~0.7.

In addition, in order to achieve the object, the present invention provides a laminated material comprising the multi-layered film and a metal thin layer which contains metals or metallic oxides, and which is laminated onto the propylene resin layer (B) of the multi-layered film.

In addition, in order to achieve the object, the present invention provides another laminated material comprising the multi-layered film, a protective layer which is laminated onto the propylene resin layer (B) of the multi-layered film, a metal thin layer which is laminated onto the protective layer, and a print layer which is laminated onto the metal thin layer. In addition, in order to achieve the object, the present invention provides a packaging material comprising the sealant film.

In addition, in order to achieve the object, the present invention provides another packaging material comprising the laminated material.

It is preferable that the packaging material comprises two laminated materials.

In addition, it is preferable for a seal strength of the packaging material to be in a range from 5 to 10 N/mm width.

In addition, in order to achieve the object, the present invention provides a manufacturing method for the packaging material comprising a knurl-sealing step.

In addition, in order to achieve the object, the present invention provides a medical instrument which is packaged with the packaging material.

In the medical instrument, it is preferable for a blood sugar measuring electrode to be packaged with the packaging material.

In addition, in the medical instrument, it is preferable for a blood sugar measuring electrode and a desiccant to be packaged with the packaging material.

Furthermore, in the medical instrument, it is also preferable to comprise an electrode reception portion for receiving the blood sugar measuring electrode, a desiccant reception portion for receiving the desiccant, and a connection portion for connecting the electrode reception portion and the desiccant reception portion.

According to the multi-layered film, the sealant film, the laminated material, the packaging material, and the medical instrument, it is possible to achieve the objects.

In addition, according to the manufacturing methods for a multi-layered film and a packaging material, it is possible to provide the excellent multi-layered film and the packaging material.

MODES FOR CARRYING OUT THE INVENTION

The present invention will be explained in detail below.

Propylene- -olefin random copolymer (a) (denoted by RPP or component (a) below), which is contained in the resin composition layer (A), is a random copolymer containing propylene and at least one a -olefin selected from oι -olefins having from 2 to 12 carbon atoms excepting 3 carbon atoms. Examples of a -olefin having from 2 to 12 carbon atoms excepting 3 carbon atoms include, ethylene, 1-butene, 3-methyl-l-butene, 3-methyl-l-pentene, 4-methyl-l-pentene, 4-dimethyl-l-pentene, vinylcyclopentane, vinylcyclohexane, and the like. These a -olefins may be used individually or in combination of two or more thereof. Among these -olefins, ethylene is preferable. The amount of -olefin with respect to propylene a -olefin random copolymer (a) is usually in a range from 3 to 10% by mass, preferably in a range from 4 to 9% by mass, and more preferably in a range from 5 to 8% by mass. If the amount of -olefin is less than 3% by mass, low-temperature heat sealability cannot be sufficiently obtained. In contrast, if it is more than 10% by mass, heat resistance deteriorates. If heat resistance deteriorates, a sealant layer, which comprises the sealant film, easily flows and the thickness of the sealant layer decreases. Due to this, heat sealability of the sealant layer deteriorates. In addition, the problem arises that a part of the sealant layer is removed, and the sealant layers are easily attached via the removed part, and a peel between the sealant layers cannot be carried out.

Moreover, a material having an excellent low-temperature heat sealability means a material having a heat seal strength in a range from 3 to 10 N/mm width, more preferably in a range from 5 to 10 N/mm width, at heat seal temperature in a range from 140 to 160°C. If a packaging material has an excellent low-temperature heat sealability, it can be easily opened.

Melt flow rate (MFR) of RPP is in a range from 5 to 35 g/10 min, preferably in a range from 10 to 30 g/10 min, and more preferably in a range from 15 to 25 g/10 min. Moreover, the MFR is measured according to JIS K 7210 at a temperature of 230°C under a load of 21.18 N. If the MFR is less than 5 g/10 min, heat sealability deteriorates. In contrast, if the MFR is more than 35 g/10 min, when the resin composition layer (corresponding to a sealant layer in a case of a sealant film) is knurl sealed, the resin composition layer (A) or the sealant layer flows, the thickness thereof decreases, and heat seal strength also deteriorates. In addition, the problem arises that a part of the sealant layer is removed, and the sealant layers are easily attached via the removed part, and a peel between the sealant layers cannot be carried out

Moreover, "a packaging material having excellent heat sealability" in this specification means a packaging material having excellent low-temperature heat sealability, the clouding property, and a feathering degree. That is, heat sealability is evaluated from low-temperature heat sealability, and the clouding property and a feathering degree, are evaluated from the peeled portion, namely, the sealed portion after peeling. Moreover, in order to obtain excellent heat sealability, the following three requirements have to be satisfied. First, the material has to have the low-temperature heat sealability in the above-mentioned range. Second, if a packaging material is opened, the sealed portion after peeling is clouded sufficient enough to recognize the peeling. Third, a feathering phenomenon cannot be observed at the sealed portion after peeling. When a packaging material does not satisfy at least one requirement, heat sealability of the packaging material is evaluated as being an inferior level.

As butene resins (b) (denoted by component (b) below), which is contained in the resin composition layer (A), any compound can be used, but ethylene-butene copolymer and polybutene-1 are preferable. In particular, polybutene-1 is more preferable.

The amount of ethylene with respect to ethylene-butene copolymer is usually in a range from 70 to 98% by mass, preferably in a range from 72 to 96% by mass, and more preferably in a range from 75 to 95% by mass. If the amount of ethylene is less than 70% by mass, heat resistance deteriorates and a feathering phenomenon can be observed at the peeled portions, that is, the peeling appearance thereof is inferior, and the clouding property is also inferior. In contrast, if it is more than 98% by mass, the openability and the clouding property deteriorate.

Moreover, the MFR of ethylene-butene copolymer, which is measured according to JIS K 7210 at a temperature of 230°C under a load of 21.18 N, is preferably in a range from 0.1 to 20 g/10 min, more preferably in a range from 0.2 to 9 g/10 min, and most preferably in a range from 0.5 to 8 g/10 min. If the MFR is less than 0.1 g/10 min, the openability deteriorates. In contrast, if the MFR is more than 20 g/10 min, peeling appearance and the clouding property deteriorate.

Polybutene-1 (hereinafter referred to as a "PB") as the component (b) is obtained by the polymerization starting from a butene- 1 monomer and is the same polyolefin as polyethylene and polypropylene. In general, PB has a high molecular weight and a high isotacticity. For the polymerization, a polymerization method using a Ziegler-Natta catalyst and a butene- 1 as a solvent, or a solution polymerization method using a hydrocarbon-base solvent such as hexane and heptane, is used.

PB is known as a polymer having rubber elasticity because it has a second order transition point lower than that of polypropylene and therefore, the flexural modulus thereof at room temperature or a low temperature is higher than that of polypropylene (see, D.G. Natta et. al., J. Polymer Sci., Vol. 25, p. 119 (1957)).

As compared with polyethylene or polypropylene, PB is excellent in the mechanical properties such as tensile strength, impact strength and tear strength, and therefore, is used as a pipe starting material, a tube or a modifier.

In the field of film, PB is used by blending it with another resin so as to impart low temperature heat sealability or easy peelability.

The properties and uses of PB are described in detail, for example, in Saishin Laminate Kako Binran (Newest Lamination Processing Handbook), pp. 861-866 (1989), Kako Gijutsu Kenkyu Kai, and I.D. Rubin, Poly(l-Butene) - its Preparation and Properties, Gordon and Breach Science Publishers, Inc., New York (1968).

PB for use in the present invention preferably has an MFR of 0.5 to 15 g/10 min according to ASTM D1238E, more preferably from 0.8 to 12 g/10 min, and still more preferably from 1 to 10 g/10 min. If the MFR is less than 0.5 g/10 min, the seal strength may be too high, whereas if it exceeds 15 g/10 min, a feathering phenomenon may occur upon peeling the sealed portion or the clouding property may be inferior at the time of peeling.

The melting point of PB, measured by a method using a differential scanning calorimeter (DSC) according to JIS K 7121, is preferably 100 to 140°C, more preferably 110 to 135°C, and most preferably 115 to 130°C. If the melting point is less than 100°C, a feathering phenomenon may occur in the portion where the sealed portion is peeled, or the clouding property is likely to be inferior at the time of peeling, whereas if it exceeds 140°C, the heat seal strength and the clouding property tend to be inferior.

PB is available, for example, under the trade name of "BEAULON" from Shell Chemical and Mitsui Chemicals, Inc. and these PBs can be suitably used.

The MFR of high-density polyethylenes (c) (which may be denoted by HDPE or component (c) below), which are contained in the resin composition layer (A), is in a range from 1 to 25 g/10 min, preferably in a range from 2 to 18 g/10 min, and more preferably in a range from 3 to 12 g/10 min. Moreover, the MFR is measured according to JIS K 7210 at a temperature of 190°C under a load of 21.18 N. If the MFR is less than 1 g/10 min, low-temperature heat sealability and the clouding property deteriorate. In contrast, if the MFR is more than 25 g/10 min, the film readily tears in a longitudinal direction or a feathering phenomenon may occur at the time of peeling.

A density of HDPE according to JIS K 7112D (method D in JIS K7112) is preferably in a range from 0.945 to 0.970 g/cm³, more preferably in a range from 0.946 to 0.965 g/cm³, and most preferably in a range from 0.947 to 0.958 g/cm³. If the density is less than 0.945 g/cm³, the moisture barrier property deteriorates as well, the clouding property at the time of peeling deteriorates. In contrast, the density is more than 0.970 g/cm³, low-temperature heat sealability and the clouding property easily deteriorate.

Linear low-density polyethylene (c) (which may be denoted by LLDPE or component (c) below), which is contained in the resin composition layer (A), is a copolymer containing ethylene and at least one Oi -olefin selected from Oi -olefins having from 3 to 20 carbon atoms. The catalyst used for manufacturing LLDPE is not limited, however, for example, to a single site catalyst, and a Ziegler-Natta catalyst can be used. Among oi -olefins having from 3 to 20 carbon atoms, ot, -olefins having from 3 to 12 carbon atoms are preferable. Specifically, propylene, 1-butene, 1-pentene, 4-methyl-l-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, and the like are preferable. In particular, propylene, 1-butene, 1-hexene, and 1-octene are more preferable. The amount of a -olefin with respect to the copolymer is usually in a range from 1 to 30 mol%, and preferably in a range from 3 to 20 mol%.

The MFR of LLDPE, which is measured according to JIS K 7210 at a temperature of 190°C under a load of 21.18 N, is in a range from 1 to 10 g/10 min, preferably in a range from 2 to 8 g/10 min, and more preferably in a range from 2.5 to 10 g/10 min. If the MFR is less than 1 g/10 min, heat seal strength becomes too large. In contrast, if the MFR is more than 10 g/10 min, a feathering phenomenon easily occurs at the time of peeling, and the appearance at the sealed portion after peeling deteriorates.

A density of LLDPE according to JIS K 7112D is usually in a range from 0.920 to 0.935 g/cm³, preferably in a range from 0.922 to 0.933 g/cm³, and more preferably in a range from 0.925 to 0.932 g/cm³. If the density is less than 0.920 g/cm³, the moisture barrier property deteriorates as well, and the clouding property and the openability at the time of peeling deteriorates. In contrast, the density is more than 0.935 g/cm³, low-temperature heat sealability deteriorates.

The blend ratio between the component (a), the component (b), and the component (c) constituting the resin composition layer (A) is preferably such that the component (a) is in a range from 50 to 80 parts by mass, the component (b) is in a range from 10 to 40 parts by mass, and the component (c) is in a range from 5 to 20 parts by mass. Moreover, the total amount of the components (a), (b), and (c) is 100 parts by mass.

When the component (c) contains both HDPE and LLDPE, the blend ratio between the component (a), the component (b), HDPE, and LLDPE, is preferably such that the component (a) is in a range from 50 to 80 parts by mass, the component (b) is in a range from 10 to 40 parts by mass, HDPE is in a range from 5 to 20 parts by mass, and LLDPE is in a range from 5 to 20 parts by mass. Moreover, the total amount of the components (a), (b), HDPE, and LLDPE is 100 parts by mass.

However, the blend ratio between the component (a), the component (b), HDPE, and LLDPE, is more preferably such that the component (a) is in a range from 60 to 78 parts by mass, the component (b) is in a range from 15 to 25 parts by mass, HDPE is in a range from 5 to 18 parts by mass, and LLDPE is in a range from 5 to 16 parts by mass

In particular, the blend ratio is most preferably such that the component (a) is in a range from 65 to 75 parts by mass, the component (b) is in a range from 17 to 23 parts by mass, HDPE is in a range from 8 to 15 parts by mass, and LLDPE is in a range from 8 to 14 parts by mass

If the blend ratio of the component (a) is less than 50 parts by mass, when a film is heat sealed using a heat seal bar, not only a pressed portion by the heat seal bar but also the vicinity of the pressed portion are heat sealed, and the appearance deteriorates. In addition, heat sealability becomes too large, and the openability also deteriorates. In contrast, if it is more than 80 parts by mass, low-temperature heat sealability deteriorates.

If the blend ratio of the component (b) is less than 10 parts by mass, the openability and the clouding property deteriorate. In contrast, if it is more than 40 parts by mass, the moisture barrier property, heat seal strength, and the clouding property deteriorate.

If the blend ratio of HDPE is less than 5 parts by mass, the openability deteriorates. In contrast, if it is more than 20 parts by mass, a film is split at the time of peeling and the appearance at the sealed portion after peeling deteriorates. In addition, low-temperature sealability also deteriorates.

If the blend ratio of LLDPE is less than 5 parts by mass, the openability deteriorates. In contrast, if it is more than 20 parts by mass, a feathering phenomenon easily occurs at the time of peeling and the appearance at the sealed portion after peeling deteriorates. Below, the propylene resin layer (B) (which may be denoted as the layer (B) below) comprising propylene resins (d) will be explained.

As propylene resins, propylene homopolymer, and random copolymer containing propylene and at least one -olefin selected from Oi -olefins having 2 to 12 carbon atoms, excepting 3 carbon atoms, which is a propylene- Oi -olefin random copolymer, are preferably used. In particular, since propylene homopolymer has excellent openability and the moisture barrier property, propylene homopolymer is more preferable.

Examples of a -olefin having from 2 to 12 carbon atoms excepting 3 carbon atoms include, ethylene, 1-butene, 3-methyl-l-butene, 3-methyl-l-pentene, 4-methyl-l-pentene, 4-dimethyl-l-pentene, vinylcyclopentane, vinylcyclohexane, and the like. These oi -olefins may be used individually or in combination of two or more thereof. Among these Oi -olefins, ethylene is preferable.

The amount of Oi -olefins with respect to propylene OL -olefin random copolymer (a) is preferably 1.5 parts by mass or less, and more preferably 1.0 parts by mass or less, and most preferably 0.8 parts by mass or less. If the amount is more than 1.5 parts by mass, the moisture barrier property and the openability deteriorate. In addition, a laminated material comprising the propylene resin layer (B) may be broken at the time of peeling.

The MFR of propylene resins (d) which is measured according to JIS K 7210 at a temperature of 230°C under a load of 21.18 N is in a range from 1 to 10 g/10 min, preferably in a range from 1 to 8 g/10 min, and more preferably in a range from 1.5 to 5 g/10 min. If the MFR is less than 1 g/10 min, low-temperature heat sealability and the clouding property deteriorate. In contrast, the MFR is more than 10 g/10 min, the propylene resin layer (B) is easily torn in a certain direction, or a feathering phenomenon easily occurs at the time of peeling.

The manufacturing method for the multi-layered film is not limited. The multi-layered film can be manufactured by well-known manufacturing methods. For example, the multi-layered film can be manufactured by adding additives into the components (a), (b), and (c), and component (d) if necessary; mixing these components using mixing roll, Banbury mixer, Henschel mixer, tumbler or ribbon blender; kneading and pelletizing the mixture using an extruder, or directly dry-blending; and forming the components by an extrusion lamination method, a co-extrusion inflation method and a co-extrusion T-die casting method.

When a multi-layered film comprising at least the resin composition layer (A) and the propylene resin layer (B) is prepared by a co-extrusion method, the film having excellent moisture barrier property and the clouding property is prepared by adjusting an extrusion temperature, that is, the die temperature, in a range from 160 to 280°C, preferably in a range from 200 to 280°C, more preferably in a range from 200 to 250°C and thereby a film is formed, and adjusting the cooling temperature in a range from 20 to 90 °C using a chill roll, preferably in a range from 40 to 80°C.

The sealant film of the present invention comprises the multi-layered film comprising the resin composition layer (A) and the propylene resin layer (B), and the resin composition layer (A) is used as a sealant layer. Moreover, the propylene resin layer (B) is used as a base material.

The layer structure of the sealant film is preferably a two-kind two-layer structure of the resin composition layer (A)/the propylene resin layer (B), because the sealant film having such layer structure has excellent functions and is economical. However, for the reasons of manufacturing process and configuration of a packaging material, the layer structure can be changed into a two-kind three-layer structure of (A)/ (B)/ (A), another multiple layer structure of (A)/ (B)/ other layer and (A)/ other layer/ (B), and the like. The other layer is preferably a polyolefin resin layer. Among these layer structures, a layer structure, in which the layers (A) and (B) are contacted, is preferable. When the layers (A) and (B) are contacted, a stability of heat sealability is improved. Due to this, it is possible to solve the problem that the vicinity of a heat sealed portion is also melt and attached, and the contents cannot be easily taken out. In addition, the moisture barrier property is also improved.

In the sealant film, the thickness ratio between the layer (A) and the layer (B)(the layer (A): the layer (B)) is preferably 0.05~0.3: 0.95~0.7, preferably to 0.08~0.25: 0.92 —0.75, and most preferably to 0.1~0.2: 0.9~0.8.

If the thickness ratio of the layer (A) is less than 0.05, when heat sealing is carried out, both of the layers (B) are partially heat sealed and this may cause the problem such that the heat seal strength elevates or on opening, the multi-layered film is cut at the heat seal end part, and as a result, the contents cannot be easily taken out. In contrast, if the thickness ratio of the layer (A) is more than 0.3, feathering takes place or the moisture barrier property of the packaging material may deteriorate.

The thickness of the sealant film is in a range from 20 to 80 β m, preferably in a range from 20 to 70 ft m, more preferably in a range from 20 to 60 β m, and most preferably in a range from 25 to 50 β m. When the sealant film comprises a packaging material, in order to avoid the penetration of the water component from the end part into the packaging material, the thickness of the layer (A) is preferably in a range from 3 to 15 β TΑ.

The laminated material of the present invention comprises the multi-layered film and a metal thin layer which contains metals or metallic oxides and which is laminated onto the propylene resin layer (B) of the multi-layered film. Moreover, the metal thin layer acts as a gas barrier layer. In addition, the other laminated material of the present invention comprises the multi-layered film, a protective layer which is laminated onto the propylene resin layer (B) of the multi-layered film, the metal thin layer which is laminated onto the protective layer, and a print layer which is laminated onto the metal thin layer.

In these laminated materials, the metal thin layer or the protective layer is laminated either using an adhesive or not. Examples of the adhesive include, urethane based adhesive, polyester based adhesive, and maleic anhydride modified polypropylene.

The metal thin film layer, which acts as a gas barrier layer, may be a layer made of aluminum foil, metallized film, silicon oxide-deposited film, or a layer comprising vinylidene chloride resin or ethylene-vinyl acetate copolymer saponified product.

The protective layer is used to improve mechanical strength of a packaging material comprising the laminated material. The protective layer may be a polyester resin layer, a polyamide resin layer, or a polycarbonate resin layer.

In addition, as long as the objects of the present invention are achieved, in order to satisfy the properties required as a packing material, other polyolefm resin layer, an oxygen absorbing layer, and an printing layer can be also laminated onto the laminated material.

Printing can be carried out on the printing layer. Examples of the printing layer include, a layer containing polyester resins, polybuthylene terephthalate resins, or polyamide resins.

The laminated material is prepared by well-known manufacturing method using well-known forming device. Examples of the manufacturing method for the laminated material include, an extrusion lamination method, a dry-lamination method, and the like.

The packaging material of the present invention comprises the sealant film. Examples of the packaging material include, a packaging container and a packaging bag, which are prepared by melting and adhering the sealant layer. Examples of a material to be adhered with the sealant layer include, a flat material, such as a film, and a three-dimensional container. The laminated material is preferable as the material to be attached to the sealant layer.

As the material to be attached to the sealant layer, as long as it attaches to the resin composition layer (A), any material can be used. However, the material preferably comprises polyolefin. Examples of the polyolefin include, olefin homopolymers, such as high-density polyethylene, low-density polyethylene, linear low-density polyethylene, polypropylene, polybutene, poly-4-methylpentene -1; copolymers containing 2 or more -olefins, such as ethylene, propylene, 1-butene, 1-hexene, 1-octene; copolymers (including graft copolymers) containing olefins, such as ethylene and propylene and unsaturated dicarboxylic acid anhydrides, such as maleic anhydride, itaconic anhydride, citraconic anhydride, endobicyclo-[2, 2, l]-hepto-5-en-2, 3-dicarboxylic anhydride; copolymer containing ethylene and unsaturated carboxylic acid or unsaturated carboxylic acid ester, such as ethylene-(meta) acrylic acid copolymer, ehtylene-(meta)acrylic acid ester copolymer; and ethylene based ternary copolymers, such as ethylene-(meta)acrylic acid ester-maleic anhydride copolymer. Among these polyolefins, polypropylene and linear low-density polyethylene are preferable.

Among the packaging materials of the present invention, a packaging material comprising a heat sealed surface, which is made of the layer (A) of the sealant film, is most preferable. The packaging material has extremely excellent openability, low-temperature heat sealability, the moisture barrier property, and the clouding property, and excellent appearance, that is, a feathering does not occur. For example, the packaging material can be prepared by arranging laminated materials such that the layers (A) and (A) are contacted, which correspond to the sealant films of the laminated materials, and sealing the laminated materials so as to seal a content to be packaged. In addition, a packaging material is also preferable, which is prepared by folding the laminated material so as to contact the layers (A) and (A), and sealing the laminated material so as to seal a content to be packaged.

The heat seal strength of the packaging material at the time of peeling is preferably in a range from 5 to 10 N/mm width. The packaging material having a heat seal strength in the range, it has excellent openability.

When the packaging material is prepared by heat sealing, it is preferable for the heat sealing to be a knurl sealing. The heat sealing temperature varies depending on a heat resistance of a content to be packaged. However, when the openability is considered, the heat sealing temperature is preferably in a range from about 120 to 180°C, more preferably in a range from about 140 to 160°C.

Moreover, the knurl sealing is a type of heat sealing. In the knurl sealing, a heat sealing bar at the surface of which a crisscross pattern or a diagonal scored pattern is formed, is used to melt and attach a material. The knurl sealing is preferably used for packaging materials which are required to have a stable seal strength and excellent moisture barrier property. When a heat sealing bar having a plane surface is used, since the entire sealed portion is sealed simultaneously, the problem arises that air is easily enclosed inside of the packaging material and wrinkles due to an expansion or a creep of a film are easily generated, and it is difficult to prepare a uniform heat seal portion. In addition, it is also difficult to obtain a stable seal strength. These problems can be solved by knurl sealing.

Although the reason is not clearly known, excellent properties of the multi-layered film, the sealant film, the laminated material, and the packaging material of the present invention are presumed attributable to the fact a cohesive peeling due to cohesive failure is generated inside of the resin composition layer (A) containing a specific amount of the components (a), (b), and (c), and whereby excellent openability and high clouding property are revealed.

In particular, although the reason is not clearly known, excellent clouding property as one object of the packaging material of the present invention is presumed attributable to the fact that the component (b) constituting the resin composition layer (A) has a higher molecular weight and a higher cohesive energy than other components (a) and (c), and therefore, when the packaging material is peeled, fine voids are generated on the interface between the component (b) and the components (a) and (c).

The constituent materials in each layer constituting the present invention may be blended with an appropriate amount of other additives commonly used for the thermoplastic resin (for example, antioxidant, weatherability stabilizer, antistatic agent, lubricant, blocking inhibitor, antifogging agent, dye, pigment, oil, wax, filler) or other thermoplastic resins within the range of not impairing the object of the present invention.

Examples of the additives include an antioxidant such as 2,5-di-tert-butylhydroquinone, 2,6-di-tert-butyl-p-cresol, 4,4'-thiobis(6-tert-butylphenol), 2,2-methylene-bis(4-methyl-6-tert-butylphenol), octadecyl-3-(3',5'-di-tert-butyl-l'-hydroxyphenyl)propionate and 4,4'-thiobis(6-butylphenol), an ultraviolet absorbent such as ethyl-2-cyano-3,3-diphenylacrylate, 2-(2'-hydroxy-5-methylphenyl)benzotriazole and 2-hydroxy-4-octoxybenzophenone, a plasticizer such as dimethyl phthalate, diethyl phthalate, wax, liquid paraffin and phosphoric acid ester, an antistatic agent such as pentaerythritol monostearate, sorbitan monopalmitate, sulfated oleic acid, polyethylene oxide and carbon wax, a lubricant such as ethylenebisstearamide and butyl stearate, a coloring agent such as carbon black, phthalocyanine, quinacridone, indoline, azo-type pigment, titanium oxide and red iron oxide, a filler such as glass fiber, asbestos, mica, wollastonite, calcium silicate, aluminum silicate and calcium carbonate, and an antiblocking agent such as silica type antiblocking agent, silicone type antiblocking agent, zeolite type antiblocking agent, talc, and polymethylmethacrylate (PMMA) particles. Many other polymer compounds may also be blended to the extent of not inhibiting the operational effect of the present invention.

Since the packaging material of the present invention has the effect that when the packaging material is opened, the heat sealed portion is reliably clouded and a reliable seal of the packaging material can be easily observed, the packaging material of the present invention is used suitably for packaging a medical content or a food. In particular, although the packaging material for medical content is required to have excellent clouding property, the openability, and the moisture barrier property and to be strictly controlled, the packaging material of the present invention is preferably used as the packaging material for medical content.

In addition, the medical instrument of the present invention comprises the packaging material and medical content. Examples of a medical instrument include, a medical instrument in which a blood sugar measuring electrode is packaged with the packaging material, and a medical instrument in which a blood sugar measuring electrode and a desiccant are packaged with the packaging material. Moreover, a desiccant is used to prevent the activity of enzyme immobilized in the blood sugar measuring electrode from decreasing. The medical instrument is prepared by superimposing the two multi-layered films while the medical content is between the two multi-layered films, and knurl sealing a part of the multi-layered films so as to reception the medical content.

In particular, the medical instrument is preferable, which comprises an electrode reception portion for receiving the blood sugar measuring electrode, a desiccant reception portion for receiving the desiccant, and a connection portion for connecting the electrode reception portion and the desiccant reception portion, and said blood sugar measuring electrode is in said electrode reception portion and said desiccant is in said desiccant reception portion.

Examples

The present invention is described in greater detail below by referring to the Examples. However, the present invention is not limited to these Examples.

Examples 1 to 48 and Comparative Examples 1 to 17

A test piece having a composition in Tables 1 to 3, which is a packaging material, was prepared by kneading, T-die casting, dry-laminating, and heat sealing. The methods for kneading, T-die casting, dry-laminating, and heat sealing are explained below.

Kneading

The components (a), (b) and (c) as constituent materials of the layer (A) were mixed in a tumbler and then the mixture was pelletized at a temperature of 190 to 210°C using a twin extruder (Model KTX37, manufactured by Kobe Steel, Ltd.).

T-Die Casting

Using each kneaded pellet material, a multi-layered film was prepared at a die temperature of 260°C using a T-die film casting machine having an aperture of 65-mmφ and a die width of 1,300 mm manufactured by Toshiba Machine Co., Ltd. by appropriately varying the total thickness, and then, cooling to 50°C. Moreover, the layer structure of the prepared multi-layered film comprising the layer (A) and the layer (B) was a two-kind two-layer structure of layer (A)/layer (B). The thickness of the layer (A) was 6 β m, and the thickness of the layer (B) was 32 β m. Dry-laminating

A laminated material having the layered structure of aluminum foil/ polyester film/ layer (B)/ layer (A) was prepared by laminating a polyester film having a thickness of 12 β m and an aluminum foil having a thickness of 15 β m on the prepared multi-layered film by a dry-lamination method.

In order to laminate these layers, an adhesive, which comprises Takelak A515 (trade name, urethane base adhesive, marketed by Takeda Pharmaceutical Industry) serving as a main component and Takenate A50 (trade name, polyester base adhesive, marketed by Takeda Pharmaceutical Industry) serving as a hardening component, was coated so that the thickness after drying is 2 β m.

Heat Sealing

A packaging material was obtained by arranging two laminated materials so as to face the layers (A), and heat sealing using a heat seal bar having a crisscross pattern with an asperity inclination angle of 55°, which is provided to a heat sealer (manufactured by Tester Sangyo Co., Ltd.) under a pressure of 2 N/cm for 1 second. Moreover, the heat seal temperature was adjusted into 140^, 150^*0, and 160°C.

Moreover, in the Examples 17 and 18 and the Comparative Examples 8 and 9, the thickness of the layers (A) and (B) were changed into 12 β m and 48 β m, respectively.

In addition, the reference symbols in Tables 1 to 3 denote the following resins.

In the component (a);

PP 1: A propylene-ethylene random copolymer having an ethylene content of 6.5 parts by mass and an MFR at a temperature of 230°C under a load of 21.18 N, of 20 (g/10 min) PP 2: A propylene-ethylene random copolymer having an ethylene content of 4.5 parts by mass and an MFR at a temperature of 230°C under a load of 21.18 N, of 14.2 (g/10 min) PP 3: A propylene-ethylene random copolymer having an ethylene content of 5.8 parts by mass and an MFR at a temperature of 230°C under a load of 21.18 N, of 6.8 (g/10 min) PP 4: A propylene-ethylene random copolymer having an ethylene content of 1.2 parts by mass and an MFR at a temperature of 230°C under a load of 21.18 N, of 12.5 (g/10 min) PP 5: A homopolypropylene having an MFR at a temperature of 230°C under a load of 21.18 N, of 20 (g/10 min).

In the component (b);

PB 1: "BEAULON BL4000 (trade name)" produced by Mitsui Chemicals Inc., which is a polybutene-1 having an MFR of 1.8 (g/10 min), a density of 0.915 (g/cm³) and a melting point of 125°C

PB 2: "BEAULON BL7000 (trade name)" produced by Mitsui Chemicals Inc., which is a polybutene-1 having an MFR of 20 (g/10 min), a density of 0.917 (g/cm³) and a melting point of 123°C

PB 3: "BEAULON M2181 (trade name)" produced by Mitsui Chemicals Inc., which is a polybutene-1 having an MFR of 1.0 (g/10 min), a density of 0.900 (g/cm³) and a melting point of 75°C

PEB: "TAFMER (trade name)" produced by Mitsui Chemicals Inc., which is an ethylene-butene copolymer having an MFR of 3.6 (g/10 min)

In the component (c);

PE 1: high-density polyethylene having a density of 0.953 (g/cm³) and an MFR at a temperature of 190°C under a load of 21.18 N, of 5.2 (g/10 min)

PE 2: high-density polyethylene having a density of 0.956 (g/cm³) and an MFR at a temperature of 190°C under a load of 21.18 N, of 20.5 (g/10 min)

PE 3: high-density polyethylene having a density of 0.949 (g/cm ) and an MFR at a temperature of 190°C under a load of 21.18 N, of 12.5 (g/10 min)

PE 4: high-density polyethylene having a density of 0.951 (g/cm³) and an MFR at a temperature of 190°C under a load of 21.18 N, of 32 (g/10 min)

PE 5: low-density polyethylene having a density of 0.923 (g/cm³) and an MFR at a temperature of 190°C under a load of 21.18 N, of 8.5 (g/10 min)

PE 6: linear low-density polyethylene having a density of 0.929 (g/cm³) and an MFR at a temperature of 190°C under a load of 21.18 N, of 2.1 (g/10 min)

PE 7: linear low-density polyethylene having a density of 0.923 (g/cm³) and an MFR at a temperature of 190°C under a load of 21.18 N, of 8.5 (g/10 min) PE 8: linear low-density polyethylene having a density of 0.932 (g/cm³) and an MFR at a temperature of 190°C under a load of 21.18 N, of 3.5 (g/10 min)

PE 9: linear low-density polyethylene having a density of 0.930 (g/cm³) and an MFR at a temperature of 190°C under a load of 21.18 N, of 20.5 (g/10 min)

PE 10: low-density polyethylene having a density of 0.924 (g/cm³) and an MFR at a temperature of 190°C under a load of 21.18 N, of 3.5 (g/10 min)

In the component (d);

PP 6: A propylene homopolymer having an MFR at a temperature of 230°C under a load of 21.18 N, of 4.5 (g/10 min)

PP 7: A propylene homopolymer having an MFR at a temperature of 230°C under a load of 21.18 N, of 2.4 (g/10 min).

PP 8: A propylene homopolymer having an MFR at a temperature of 230°C under a load of 21.18 N, of 15.4 (g/10 min).

PP 9: A propylene-ethylene random copolymer having an ethylene content of 5.2 parts by mass and an MFR at a temperature of 230°C under a load of 21.18 N, of 4.8 (g/10 min)

PP 10: A propylene-ethylene random copolymer having an ethylene content of 3.5 parts by mass and an MFR at a temperature of 230°C under a load of 21.18 N, of 11.8 (g/10 min)

The obtained packaging material in the Examples and the Comparative Example was evaluated as follows. The results are shown in the Tables 1 to 3.

Seal strength

The obtained packaging materials was cut into a width of 15 mm, and a 180° peel strength thereof was determined at a pulling rate of 300 mm/min using a tension tester (Model RTA-100, manufactured by Olientech). In the test, an average of 10 test pieces was determined.

Clouding property

After the determination of the seal strength of the packaging material of which the heat seal temperature was 140°C, the clouding property of the peeled heat seal portion for the test pieces was visually inspected. Evaluation was performed according to the following criteria.

O: The peeled heat seal portion was thoroughly clouded and the clouding was easily confirmed

Δ: The peeled heat seal portion was slightly clouded and the clouding was not easily confirmed

X : The peeled heat seal portion was not clouded at all

Appearance

After the determination of the seal strength, the peeled portion was visually judged as to whether or not feathering occurred, according to the following criteria.

O: Feathering was not observed at all

Δ: Feathering was partially observed

X : A conspicuous feathering was observed and the appearance was bad

Moisture Transmission Rate

In accordance with ASTM E96, the moisture transmission rate at a temperature of 37.8°C and a relative humidity of 90 % was measured using a moisture permeation tester PERMATRAN-W manufactured by Modern Control Ltd.

Table 2-2

Table 3-2

Claims

1. A multi-layered film comprising: a resin composition layer (A) containing (a) propylene- a -olefin random copolymers, (b) butene resins, and (c) high-density polyethylenes and/or linear low-density polyethylenes; and a propylene resin layer (B) containing (d) propylene resins.

2. A multi-layered film according to claim 1, wherein a blend ratio between said components (a), (b), and (c) is such that 50 to 80 parts by mass of said component (a), 10 to 40 parts by mass of said component (b), and 5 to 20 parts by mass of said component (c), and the total amount of said components (a), (b), and (c) is 100 parts by mass.

3. A multi-layered film according to claim 1, wherein said propylene- -olefin random copolymer is ethylene-propylene random copolymers containing 3 to 10% by mass of ethylene.

4. A multi-layered film according to claim 1, wherein said butene resin is polybutene-1.

5. A multi-layered film according to claim 1, wherein said polybutene-1 has a range from 0.5 to 15 g/min of a melt flow rate according to ASTM D1238E and a range from 100 to 140°C of a melting temperature according to JIS K 7121.

6. A multi-layered film according to claim 1, wherein said high-density polyethylene has a range from 0.945 to 0.970 g/cm³ of a density according to JIS K 7112D and a range from 2 to 25 g/10 min of a melt flow rate according to JIS K 7210.

7. A multi-layered film according to claim 1, wherein said linear low-density polyethylene has a range from 0.920 to 0.935 g/cm³ of a density according to JIS K 7112D and a range from 1 to 10 g/10 min of a melt flow rate according to JIS K 7210.

8. A multi-layered film according to claim 1, wherein said propylene resins is propylene homopolymer.

9. A manufacturing method for a multi-layered film comprising the steps of: in a co-extrusion T-die casting method, forming a film at 160 to 250°C, which comprises a resin composition layer (A) comprising (a) propylene- Oi -olefin random copolymers, (b) butene resins, and (c) high-density polyethylenes and/or linear low-density polyethylenes; and a propylene resin layer (B) comprising (d) propylene resins; and cooling it to 40 to 80°C

10. A sealant film, wherein the sealant film comprises said multi-layered film according to claim 1, and said resin composition layer (A) is used as a sealant layer.

11. A sealant film according to claim 10, wherein a total thickness of said resin composition layer (A) serving as a sealant layer and said propylene resin layer (B) is in a range from 20 to 70 β m, and a thickness ratio between said resin composition layer (A) serving as a sealant layer and said propylene resin layer (B) (layer (A): layer (B)) is in a range from 0.05^0.3: 0.95~0.7.

12. A laminated material, wherein the laminated material comprises said multi-layered film according to claim 1 and a metal thin layer which contains metals or metallic oxides and which is laminated onto said propylene resin layer (B) of said multi-layered film.

13. A laminated material, wherein the laminated material comprises said multi-layered film according to claim 1, a protective layer which is laminated onto said propylene resin layer (B) of said multi-layered film, a metal thin layer which is laminated onto said protective layer, and a print layer which is laminated onto said metal thin layer.

14. A packaging material comprising the sealant film according to claim 10.

15. A packaging material comprising the laminated material according to claim 12.

16. A packaging material according to claim 15, that comprise two laminated materials according to claim 12.

17. A packaging material according to claim 14, that has a seal strength in a range from 5 to 10 N/mm width.

18. A packaging material according to claim 15, that has a seal strength in a range from 5 to 10 N/mm width.

19. A manufacturing method for a packaging material comprising the step of: knurl sealing said sealant films according to claim 10.

20. A manufacturing method for a packaging material comprising the step of: knurl sealing said laminated materials according to claim 12.

21. A medical instrument packaged with the packaging material according to claim 14.

22. A medical instrument packaged with the packaging material according to claim 15.

23. A medical instrument according to claim 21, wherein a blood sugar measuring electrode is packaged.

24. A medical instrument according to claim 22, wherein a blood sugar measuring electrode is packaged.

25. A medical instrument according to claim 21, wherein a blood sugar measuring electrode and a desiccant are packaged.

26. A medical instrument according to claim 22, wherein a blood sugar measuring electrode and a desiccant are packaged.

27. A medical instrument according to claim 25 comprising an electrode reception portion for receiving the blood sugar measuring electrode, a desiccant reception portion for receiving the desiccant, and a connection portion for connecting the electrode reception portion and the desiccant reception portion, and said blood sugar measuring electrode is in said electrode reception portion and said desiccant is in said desiccant reception portion.

28. A medical instrument according to claim 26 comprising an electrode reception portion for receiving the blood sugar measuring electrode, a desiccant reception portion for receiving the desiccant, and a connection portion for connecting the electrode reception portion and the desiccant reception portion, and said blood sugar measuring electrode is in said electrode reception portion and said desiccant is in said desiccant reception portion.