JP2001253026A - Laminated film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated film suitable as a packaging material for use in food and medical fields excellent in opening properties and the stability of whitening resistance, stem barrier properties and seal strength at the time of use as a sealant film. SOLUTION: The laminated film consists of at least two layers, that is, a layer (A) comprising a resin composition containing 50-80 mass % of (a) propylene/α-olefin random copolymer with an α-olefin content of 3-10 mass % and a melt flow rate of 5 g/10 min or more, 5-20 mass % of (b) high density polyethylene with a density of 0.940-0.965 g/cm3 and a melt flow rate of 2-10 g/10 min, 2-20 mass % of (c) a polystyrene-containing resin composition with a styrene content of 20-60 mass % and 7-18 mass % of (d) straight chain polyethylene with a density of 0.920-0.935 g/cm3 and a melt flow rate of 1-25 g/10 min and a polypropylene layer (B).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a laminated film which is excellent in opening property, whitening property, steam barrier property and stability of seal strength when used as a sealant film and is suitable as a packaging material for food and medical fields. About. In particular, it is suitable as a sealant film for a package for performing knurl sealing, such as a package for a blood glucose level measurement electrode.

[0002]

2. Description of the Related Art Hitherto, polypropylene films have been used as various food packaging materials and various medical packaging materials by making use of features such as low cost, heat resistance, chemical resistance and easy heat sealing. In food packaging, aluminum foil, vinylidene chloride resin and saponified ethylene-vinyl acetate copolymer resin are used as gas barrier layers, combined with polyamide resin layers and polyester resin layers, etc., and heat seal layers are made of polyolefins such as polypropylene and polyethylene. A series resin is used. On the other hand, in medical packaging, a polyolefin-based resin is similarly used as a heat seal layer.

[0003] As an easily openable sealant film,
Resins obtained by graft-polymerizing styrene onto a polyolefin resin (JP-A-56-136833, JP-A-56-1)
No. 80502, JP-A-56-127613,
JP-A-57-185309, JP-A-61-155
413, JP-A-5-29045, etc.). In addition, as a sealant film of a package for performing knurling such as a package for a blood glucose level measurement electrode, a resin composition obtained by mixing linear polyethylene with low melting point polypropylene is used as a sealant layer, and this layer is used as a base material layer. What laminated | stacked the homopolypropylene is used.

[0004]

However, the former has problems such as high cost and not economical, poor mechanical strength due to low tensile elongation, and poor steam barrier properties. In the latter case, there is a problem that the heat seal strength is so high that it is difficult to open or that the allowable range of the heat seal temperature is narrow and the workability is poor. An object of the present invention is to provide a food packaging material which is more excellent in opening property, whitening property, water vapor barrier property and seal strength stability, excellent in MD direction and TD direction tearability, and is more suitable for knurl seal than conventional ones. A laminated film suitable as a medical packaging material is provided.

[0005]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that the above object can be achieved by laminating a specific resin composition on polypropylene,
Based on this finding, the present invention has been completed. That is, the present invention provides (A) (a) a propylene-α-olefin random copolymer having an α-olefin component content of 3 to 10% by mass and a melt flow rate of 5 g / 10 min or more; Is 0.940 to 0.958 g / cm ³ ,
High-density polyethylene having a melt flow rate of 2 to 10 g / 10 minutes, and (c) a styrene content of 20 to 60.
Polystyrene-containing resin composition which is 2% by mass. A resin composition containing 2 to 20% by mass, and (d) a density of 0.910
0.935 g / cm ³ , melt flow rate is 1 to 10
An object of the present invention is to provide a laminated film composed of at least two layers: a layer composed of a resin composition containing a linear polyethylene having a g / 10 min, and (B) a polypropylene layer.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The (a) propylene-α-olefin random copolymer in the present invention has an α-olefin component content of 3 to 10% by mass and a melt flow rate (based on JIS K7210; ℃, load 2
1.Measurement under a condition of 18 N) (hereinafter abbreviated as “MFR”) is 5 g / 10 min or more (hereinafter referred to as “R”).
PP ”). The content of the α-olefin component is preferably 4 to 9% by mass, more preferably 5 to 8% by mass. When the content of the α-olefin component is less than 3% by mass, low-temperature heat sealing is inferior. If it exceeds 10% by mass, the sealing strength of the knurl seal may be reduced,
On the contrary, it is not preferable because it causes a problem that the heat sealing layer flows and adheres to each other and the package cannot be opened. The α-olefin has 2 to 1 carbon atoms.
2, for example, ethylene, 1-butene,
3-methyl-1-butene, 3-methyl-1-pentene, 4
-Methyl-1-pentene, 4-dimethyl-1-pentene, vinylcyclopentane, vinylcyclohexane and the like. These α-olefins may be used alone or as a mixture of two or more.

[0007] The MFR of RPP in the present invention is 5 g / 1.
It is 0 minute or more, preferably 10 to 30 g / 10 minutes, and more preferably 15 to 25 g / 10 minutes.
If the MFR is less than 5 g / 10 minutes, the heat sealing properties are inferior, and therefore it is not preferable. On the other hand, the upper limit of MFR is 3
It is about 5 g / 10 minutes. If it exceeds 35 g / 10 minutes, problems may occur such as a decrease in sealing strength at the time of knurling, and conversely, the portions where the heat seal layer has flowed adhere to each other and cannot be opened.

(B) High-density polyethylene according to the present invention
Has a density of 0.940 to 0.965 g / cm^ThreeAnd Mel
Flow rate (based on JIS K7210, temperature 1
(Measured under the conditions of 90 ° C. and a load of 21.18 N)) is 2 to 10 g
/ 10 minutes. Preferred for density
Is 0.942 to 0.960 g / cm^ThreeAnd more preferred
Or 0.945 to 0.958 g / cm^ThreeIt is. density
Is 0.940 g / cm ^ThreeIf less, heat seal strength is high
Whitening when too hot or when the heat-sealed part is peeled off
Is unfavorably affected. On the other hand, 0.965 g /
cm^ThreeIf it exceeds, impact resistance and heat seal strength will be exhibited.
It is not preferable because problems such as not occurring occur. Also, Mel
The flow rate is preferably 3 to 8 g / 10
Min, more preferably 4 to 6 g / 10 min. Me
If the flow rate is less than 2 g / 10 minutes,
Or increase in low-temperature heat sealability.
Does not appear. On the other hand, if it exceeds 10 g / 10 minutes, the whitening property and
When the seal seal is performed, the seal layer flows and becomes thin.
The seal strength may be reduced, or conversely, the seal layer may flow.
Can cause problems such as being unable to open
Is not preferred.

The (c) polystyrene-containing resin composition of the present invention has a styrene content of 20 to 60% by mass.
Is a resin composition. The content of the styrene component is preferably 25 to 55% by mass, and more preferably 30 to 50% by mass. When the content is less than 20% by mass, the whitening property after peeling of the seal portion is poor. On the other hand, if it exceeds 60% by mass, the seal strength is reduced and phase separation is caused, which may undesirably impair the appearance of the molded product. Specific examples of the component (c) include a resin obtained by graft-modifying a styrene monomer to a polyolefin. These resins are described in the above-mentioned JP-A-56-136833. As a commercially available resin, “VMX” manufactured by Mitsubishi Chemical Corporation can be mentioned. Other examples include mixtures with polyolefin, polystyrene and styrene-conjugated diene block copolymer block derivatives. Examples of the styrene-conjugated diene block copolymer block derivative include a random copolymer of a styrene monomer and a conjugated diene, a block copolymer, or a hydrogenated copolymer thereof. Further, the derivative may be a random or block copolymer containing one or more α-olefin components as the third component. Specific examples of the derivative include a styrene-ethylene / butylene copolymer (SE
B), styrene-ethylene-butylene-styrene block copolymer (SEBS), styrene-ethylene-propylene-copolymer (SEP), styrene-ethylene-propylene-styrene block copolymer (SEPS), and the like. Among these, SEBS and SEPS are particularly preferred. The styrene content of these derivatives is usually 50 to 70% by mass, preferably 55 to 70% by mass, and more preferably 60 to 69% by mass. If the styrene content is less than 50% by mass, openability and whitening properties are poor. On the other hand, if the content exceeds 70% by mass, the knurl sealability is inferior.

As the linear polyethylene (d) in the present invention, there may be mentioned a copolymer of ethylene and at least one selected from α-olefins having 3 to 12 carbon atoms. As the α-olefin, specifically, propylene, 1-butene, 1-pentene, 4-methyl1-
Pentene, 1-hexene, 1-octene, 1-decene,
1-dodecene and the like. Α- in the copolymer
The content of the olefin component is usually 30 mol% or less, preferably 3 to 20 mol%. The density of the linear polyethylene, as measured in accordance with JIS K7112, a 0.920~0.935g / cm ^3, more preferably from 0.921~0.930g / cm ^3, particularly preferably is a 0.922~0.928g / cm ^3. If the density is less than 0.920 g / cm ³ , the sealing strength becomes too high. On the other hand, when it exceeds 0.935 g / cm ³ , the whitening property when the seal portion is peeled off is inferior, so that it is not preferable. Melt flow rate (measured at a temperature of 190 ° C and a load of 21.18 N according to JIS K7210)
Is 1 to 25 g / 10 min, more preferably 1.5 g
２０20 g / 10 min. Melt flow rate 1g /
If the time is less than 10 minutes, the sealing strength becomes too high and the opening property is poor. On the other hand, if it exceeds 25 g / 10 minutes, the whitening property when the sealing portion is peeled off is inferior.

The composition ratio of the component (a) in the layer (A) of the present invention is 50 to 80% by mass, preferably 60 to 7% by mass.
It is 8% by mass, more preferably 65 to 75% by mass. If the composition ratio is less than 50% by mass, the sealing strength will decrease. On the other hand, when the content exceeds 80% by mass, the heat sealing strength becomes too high, and the opening property is inferior. (A)
The composition ratio of the component (b) in the layer is 5 to 20% by mass, preferably 7 to 18% by mass, and more preferably 8 to 15% by mass. If the composition ratio is less than 5% by mass, the sealing strength becomes too high and the opening property is poor. On the other hand, if the content exceeds 20% by mass, the gel and fish eyes of the molded body increase, and the impact resistance decreases, which is not preferable. Also,
The composition ratio of the component (c) in the layer (A) is 2 to 20% by mass, preferably 5 to 18% by mass, and more preferably 7 to 15% by mass. When the composition ratio is less than 2% by mass, the whitening property when the seal portion is peeled off is inferior. Meanwhile, 2
If it exceeds 0% by mass, the sealing strength is impaired and the appearance such as fluffing is reduced, which is not preferable. further,
The composition ratio of the component (d) in the layer (A) is 7 to 18% by mass, preferably 7 to 15% by mass, and more preferably 8 to 15% by mass. If the composition ratio is less than 5% by mass, the sealing strength becomes too high and the opening property is poor. Meanwhile, 1
If it exceeds 8% by mass, the whitening property is inferior, the sealing strength is impaired, and the appearance such as fluffing is deteriorated.

In the present invention, the polypropylene (B) includes a propylene homopolymer and propylene with 2 carbon atoms.
To 12 (excluding 3) random copolymers with α-olefins. The content of the α-olefin component is preferably at most 5% by mass, more preferably 4% by mass or less, and particularly preferably 3% by mass or less.

For the resin composition of the layer (A) and the polypropylene of the layer (B) constituting the present invention, other additives (for example, antioxidant, weathering stabilizer, Antistatic agents, lubricants, antiblocking agents, antifogging agents, dyes, pigments, oils, waxes, fillers, etc.) and other thermoplastic resins can be appropriately compounded within a range that does not impair the object of the present invention. Examples of such additives include 2,5-di-t-butylhydroquinone as an antioxidant,
2,6-di-t-butyl-p-cresol, 4,4′-
Thiobis- (6-t-butylphenol), 2,2′-
Methylene-bis (4-methyl-6-t-butylphenol), octadecyl-3- (3 ′, 5′-di-t-butyl-1′-hydroxyphenyl) propionate, 4,
4'-thiobis-6-butylphenol), and as an ultraviolet absorber, ethyl-2-cyano-3,3'-diphenylacrylate, 2- (2'-hydroxy-5-methylphenyl) benzotriazole, 2-hydroxy-4 Octoxybenzophenone, dimethyl phthalate, diethyl phthalate as a plasticizer, wax, liquid paraffin, phosphate ester, pentaerythritol monostearate, sorbitan monopalmitate as an antistatic agent, sulfated oleic acid, polyethylene oxide, Carbon wax, ethylene bis stearamide, butyl stearate, etc. as a lubricant, carbon black, phthalocyanine, quinacridone, indoline, azo pigment, titanium oxide, bengalara, etc. as a coloring agent, glass fiber, asbestos, mica as a filler Wollastonite, calcium silicate, aluminum silicate, calcium carbonate also,
Many other high molecular compounds can also be blended to such an extent that the effects of the present invention are not impaired.

The method for obtaining the resin composition of the present invention is not particularly limited, and a known mixing method can be used. For example, there is a method of mixing each component with a mixing machine such as a mixing roll, a Banbury mixer and a Henschel, tumbler, ribbon blender or the like, and then pelletizing the mixture using an extruder. The laminated film of the present invention is a film comprising at least two layers of the above (A) layer and (B) layer. A single layer film having only the layer (A) causes problems such as a lack of whitening property and seal strength. Such an effect is exhibited only by laminating the layer (B) on the layer (A). As the lamination method, a known method such as a coextrusion molding method and a coextrusion lamination method can be used. The thickness of the laminated film of the present invention is usually 20 to 70 μm, preferably 25 to 60 μm.
μm, and more preferably 30 to 55 μm. When the thickness is less than 20 μm, the impact strength, the sealing strength and the water vapor permeability are inferior. On the other hand, if it exceeds 70 μm, it is not preferable because it is inferior in opening property, whitening property and the like. The thickness ratio of the (A) layer and the (B) layer of the laminated film in the present invention is (A) layer /
(B) layer = 1/9 to 9/1, preferably 1.5 / 8.5 to 8.5 / 1.5, more preferably 2/8 to 8/2. Regarding the layer constitution, two types of two layers (A) layer / (B) layer and (A) layer / (B) layer /
Two types and three layers of the (A) layer are preferred. Further, another polyolefin-based resin layer may be further laminated and used within a range not to impair the object of the present invention.

For the laminated film of the present invention, a known dry laminating machine or the like is used, and a gas such as aluminum foil, metal-deposited film, silicon oxide-deposited film, vinyldene chloride resin and saponified ethylene-vinyl acetate copolymer is used. Other materials such as a barrier layer, a polyester resin layer, a polyamide resin layer, and a polycarbonate resin layer can be laminated and used. As a method of using the laminated film of the present invention, the layers (A) may be heat-sealed with each other, or the layer (A) may be heat-sealed with another polyethylene film, polypropylene film or the like.

[0016]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples. The methods for measuring various physical properties used in the present invention are described below. Seal Strength Using a tensile tester (Model RTA-100) manufactured by Orientec, T-peel strength was measured at a tensile speed of 300 mm / min. Whitening The test piece after measuring the seal strength was visually observed for whitening, and evaluated in the following three stages. ○ ・ ・ ・ The peeled part is sufficiently whitened, making it easy to confirm whitening △ ・ ・ ・ The peeled part is whitened even if it is thin, making it difficult to confirm × ・ ・ ・ The peeled part is not whitened at all With respect to the peeled portion after the strength measurement, the presence or absence of fluff was visually evaluated in the following three stages.・ ・ ・: No fuzz is observed at all. △: Fuzz is partially observed. ×: The fuzz phenomenon is remarkable, and the appearance is inferior. "PERMATRAN-W") at a temperature of 37.8 ° C and a relative humidity of 90%.

The materials used are shown below. [(A) Layer Component Resin] (a) Component RPP1: Ethylene component content is 7.2% by mass, MFR
Is 21 g / 10 min, RPP2: ethylene component content is 5.1% by mass, MFR
Is 12.5 g / 10 min propylene-ethylene random copolymer RPP3: Propylene-ethylene random copolymer having ethylene content of 2.3% by mass and MFR of 2.6 g / 10 min (for comparative example) (B) Component PE1: density 0.958 g / cm ³ , MFR 5.8
g / 10 min high density polyethylene PE2: density 0.945 g / cm ³ , MFR 3.2
g / 10 min high density polyethylene PE3: density 0.922 g / cm ³ , MFR 7.4
g / 10 min. low density polyethylene (for comparative example) (c) component PS1: Mitsubishi Chemical Corporation “Trade name: VMX X100F” PS2: Twin screw extruder (Kebe Steel Co., Ltd., K
Resin composition kneaded with TX37 type "A & M Styrene Co., Ltd." Product name: Stylon 685 "45 mass%-Propylene-ethylene random copolymer (ethylene component content 5.6 mass%, MFR 12.8 g) / 10 min) 50% by mass ・ SEBS (trade name: Tuftec L50, manufactured by Asahi Kasei Corporation)
9 "5% by mass PS3: The above three components were mixed in a short single-screw extruder (manufactured by Yato Machine Co., Ltd., V
(D) Component PE4: MFR 2 g / 10 min, density 0.929 g /
Linear polyethylene of cm ³ [B layer component resin] PP1: Homopropylene having an MFR of 7.5 g / 10 min (trade name: Jayaromar Rex PC600S manufactured by Nippon Polyolefin Co., Ltd.) PP2: MFR of 7.2 g / Propylene-ethylene random copolymer having an ethylene component content of 5.6% by mass for 10 minutes

Examples 1 to 8 and Comparative Examples 1 to 5 After kneading with the types and amounts shown in Table 1, the diameter of
A laminated film was prepared at a die temperature of 250 ° C. using a T-die film forming machine manufactured by Toshiba Machine Co., Ltd. having a diameter of 5 mm and a die width of 1,300 mm. The layer configuration is (A) layer /
(B) Two layers consisting of layers were used. The thickness of each layer film is shown in Table 1. The water vapor transmission rate of each of the obtained films was measured. Next, the layer (B) side of each laminated film was
It was laminated on 2 μm polyester by a dry lamination method. Using a heat sealer (manufactured by Tester Sangyo Co.), the (A) layer surfaces of the obtained laminated film were pressed with a twill-shaped heat seal bar having a projection and depression inclination angle of 55 ° at a pressure of 0.2 MPa.
a, Sealing was performed under the condition of a time of 1 second. Seal temperature is 1
The test was performed at three levels of 30, 150 and 170 ° C. The seal strength of each of the obtained seal portions was measured. Further, the whitening property and the appearance were evaluated for the sample at the sealing temperature of ° C.

Comparative Example 6 A styrene-grafted polyethylene film manufactured by Wada Chemical Co., Ltd. ("VMX Y02FT") as a layer component.
The procedure was performed in the same manner as in Example 1, except that was used. Table 2 shows the above results.

[0020]

[Table 1]

[0021]

[Table 2]

[0022]

When the laminated film of the present invention is used as a sealant film, it is excellent as a packaging material in the food and medical fields which is excellent in openability, whitening property, steam barrier property and stability of seal strength. . In particular, it is suitable as a sealant film for a package for performing knurl sealing, such as a package for a blood glucose level measurement electrode.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 25/04 C08L 25/04 25/10 25/10 // C08J 5/18 CES C08J 5/18 CES F term (reference) 4F071 AA12 AA14 AA16 AA19 AA20 AA21 AA22 AA75 AA76 AA82 AA88 AH04 BC01 BC12 4F100 AK03A AK03J AK05A AK07B AK12A AK12J AK28A AK28J AK63A AK64B AK66A AL01A AL05A BA02 GB23 GB66 JD04 JL00 JL11 JL14 4J002 AC025 AC083 BB005 BB032 BB034 BB054 BB141 BB151 BB154 BC033 BC053 BN033 BP013 BP033 GG02

Claims (3)

[Claims] (A) (a) 50-80% by mass of a propylene-α-olefin random copolymer having an α-olefin component content of 3 to 10% by mass and a melt flow rate of 5 g / 10 minutes or more; (B) The density is 0.940-0.
965 g / cm ³ , melt flow rate 2-10 g /
5 minutes to 20% by mass of high density polyethylene which is 10 minutes,
(C) 2 to 20% by weight of a polystyrene-containing resin composition having a styrene content of 20 to 60% by mass and (d)
A layer comprising a resin composition containing 7 to 18% by weight of linear polyethylene having a density of 0.920 to 0.935 g / cm ³ and a melt flow rate of 1 to 25 g / 10 minutes;
(B) a laminated film composed of at least two layers with a polypropylene layer. (C) a polystyrene-containing resin composition,
50-70% by mass of polyolefin, styrene resin
Styrene-conjugated diene derivative having 25 to 45% by mass and a styrene content of 50 to 70% by mass 2 to 15% by mass
The laminated film according to claim 1, which is: 3. The laminated film according to claim 1, wherein (B) the polypropylene layer is a homopolypropylene or a propylene-ethylene random copolymer having an ethylene component content of 4% by mass or less.