JP7119866B2 - POLYOLEFIN RESIN FILM AND HEATING PACKAGE USING THE SAME - Google Patents

Description

TECHNICAL FIELD The present invention relates to a polyolefin resin film and a package for heat treatment using the same, and more specifically, even if heat treatment under pressure such as pressurized steam treatment or pressurized hot water treatment is performed, deformation hardly occurs. , relates to a polyolefin resin film having excellent heat resistance as well as good transparency, flexibility and impact resistance, and a package for heat treatment using the same.

The performance required for packaging bags that need to be sterilized and sterilized by pressure treatment, such as retort packaging and infusion bags for medical solutions, is transparency so that the contents can be checked, and drainage without opening air holes. Low-temperature impact resistance to prevent bag breakage even when handled roughly during transportation in extremely cold regions (e.g. -20°C environment), sterilization at 121°C, no deformation or fusion even after sterilization heat resistance and the like for
For infusion bags in particular, vinyl chloride resin was once used as a material that satisfies the above performance requirements. Therefore, it has been replaced by polyolefin resin.

Infusion bags, which are mainly made of polyethylene, are excellent in flexibility and impact resistance, but have poor heat resistance. cannot be satisfied (see, for example, Patent Document 1). On the other hand, an infusion bag mainly composed of polypropylene has good heat resistance, but it is hard as an infusion bag material and lacks impact resistance at low temperatures. (See, for example, Patent Document 2).

Therefore, a technique has been disclosed in which an elastomer component is added to polypropylene to impart flexibility and impact resistance (see, for example, Patent Document 3). However, the heat resistance of polypropylene is sacrificed, and low-molecular-weight components bleed out after sterilization, resulting in deterioration of transparency. There is also a disclosure of a technique for adding a styrene elastomer as an elastomer component (see, for example, Patent Document 4), which improves performance, but styrene elastomers are more expensive than olefin elastomers, and styrene elastomers are more expensive than olefin elastomers. Since the amount of ingredients is too large, a problem remains in terms of cost.

Separately, a film obtained by blending an ethylene-based elastomer polymerized using a metallocene-based catalyst with a propylene-ethylene block copolymer polymerized using a metallocene-based catalyst has been proposed. It has been shown that it is improved and has excellent flexibility, heat resistance, and low-temperature impact resistance (see, for example, Patent Document 5). Blending impairs the transparency, so it is not sufficient as a medical film.

On the other hand, a laminated film of a polypropylene resin having excellent heat resistance and transparency and a polyethylene resin having excellent flexibility and low-temperature impact resistance has also been proposed. Generally, it is well known that a laminate of a polypropylene-based resin and a polyethylene-based resin has a low interfacial strength (see, for example, Patent Document 6), but a polypropylene-based resin and a polyethylene-based resin that are polymerized using a metallocene-based catalyst The laminate has a significantly improved interfacial strength (see Patent Documents 7 to 9, for example). In the layer structure shown in Patent Document 7, although the interfacial strength of each layer is improved, the rigidity of the propylene-based resin single layer is too high, so the flexibility is insufficient and the film is insufficient as a medical film. rice field. In addition, the layer structure shown in Patent Document 8 is excellent in flexibility and low-temperature impact resistance, but since the outer layer is a polyethylene resin, it has heat resistance only up to 115 ° C sterilization, and is generally required as a global standard. Insufficient heat resistance for sterilization at 121°C. Furthermore, Patent Document 9, Sample 11 discloses a laminate of a high melting point propylene-ethylene block copolymer polymerized using a Ziegler catalyst and a metallocene polyethylene resin having excellent heat resistance. A material that has both the excellent heat resistance of propylene resin, the flexibility of propylene resin due to the block copolymer component, and the flexibility and low-temperature impact resistance of metallocene polyethylene resin is indicated. , the interfacial strength between the propylene resin layer and the ethylene resin layer is greatly reduced. In particular, the block copolymer component polymerized with a Ziegler catalyst shows a marked decrease in the interfacial strength after sterilization at 121°C, and the propylene resin layer and the ethylene resin layer are separated. Since it easily peeled off, the performance was insufficient for practical use.

JP-A-9-308682 JP-A-9-99036 JP-A-9-75444 JP-A-2006-27653 JP 2011-68116 A JP 2007-253993 A JP 2007-245453 A JP 2014-180326 A JP 2007-245490 A

Therefore, in view of the above problems, an object of the present invention is to provide a polyolefin film having excellent flexibility, transparency, heat resistance, impact resistance, especially impact resistance at low temperatures (for example, 5 ° C.), and 121 To provide a polyolefin resin film capable of maintaining the interfacial strength of each layer and suppressing the peeling of a propylene resin layer and an ethylene resin layer even when subjected to high temperature heat treatment such as °C, and a package for heat treatment using the same. It is in.

The present inventors conducted various studies and analyzes in order to solve the above problems, and found that in a polyolefin resin film formed by laminating a plurality of layers, a specific propylene resin and a specific ethylene resin, It was found that the above problems could be solved in a well-balanced manner by using a propylene-based block copolymer obtained with a specific metallocene catalyst in the intermediate layer of the film. The present invention has been made based on the knowledge that it can be obtained.

The present invention provides the following polyolefin resin film and a package for heat treatment using the same.
[1]
At least three layers are laminated in the order of the first layer, the second layer and the third layer,
The first layer contains a first ethylene resin composition containing a first ethylene-α-olefin copolymer,
The first ethylene-α-olefin copolymer has a density in the range of 0.899 to 0.935 g/cm ³ and a melt flow rate (190°C, 2.16 kg) in the range of 1 to 10 g/10 minutes. is;
the second layer comprises a second propylene resin composition comprising a second propylene resin and a second ethylene-α-olefin copolymer;
The second propylene resin contains 30 to 70% by weight of a propylene polymer having a melting peak temperature of 120 to 170° C. in DSC measurement, and an α-olefin content of 7 to 30%, based on 100% by weight of the second propylene resin. 70 to 30% by weight of a propylene-α-olefin random copolymer, and a melt flow rate (230°C, 2.16 kg) in the range of 0.5 to 20 g/10 minutes;
The second ethylene-α-olefin copolymer is a metallocene-based ethylene-α-olefin copolymer and has a density in the range of 0.880 to 0.920 g/cm ³ . 10 to 40 wt% of the second ethylene-α-olefin copolymer in wt%;
the third layer comprises a third propylene resin composition comprising a third propylene resin;
The third propylene resin has a melting peak temperature in the range of 150 to 170° C. in DSC measurement and a melt flow rate (230° C., 2.16 kg) in the range of 2 to 20 g/10 minutes;
Polyolefin resin film.
[2]
The polyolefin resin film according to [1], wherein the second propylene resin contained in the second propylene resin composition is a metallocene propylene resin.
[3]
The polyolefin resin film according to [2], wherein the first ethylene-α-olefin copolymer contained in the first ethylene resin composition is a metallocene ethylene-α-olefin copolymer. .
[4]
Any one of [1] to [3], wherein 0 to 3.0% by weight of a styrene-based elastomer is contained in a total of 100% by weight of the propylene or ethylene resin composition contained in all of the first to third layers. The polyolefin resin film according to 1.
[5]
A package for heat treatment, comprising the polyolefin resin film according to any one of [1] to [4].
[6]
The package for heat treatment according to [5], which is an infusion bag that can be sterilized at 121°C.

According to the polyolefin-based resin film of the present invention, a specific propylene resin composition, a propylene-based block copolymer polymerized using a specific metallocene catalyst, and a specific ethylene resin composition are used for each laminated layer. It is an olefin resin film that is excellent in flexibility, transparency, heat resistance, impact resistance, especially impact resistance at low temperatures (for example, 5 ° C.), and is subjected to high temperature heat treatment such as 121 ° C. Also, it is possible to provide a polyolefin resin film capable of maintaining the interfacial strength of each layer and a package for heat treatment using the same.

The polyolefin resin film of the present invention is a multilayer film in which at least three layers are laminated in the order of the first layer, the second layer and the third layer, and each layer is described in detail below. It includes a propylene resin composition that satisfies the conditions, a propylene-based block copolymer polymerized using a metallocene catalyst, and an ethylene resin composition. However, the package for heat treatment of the present invention contains the polyolefin resin film of the present invention. The polyolefin resin film of the present invention and each component thereof, the method for producing the polyolefin resin film and each component thereof, and the package for heat treatment using the polyolefin resin film of the present invention are described in detail below.

<<First Layer>>
The first layer (hereinafter sometimes referred to as "innermost layer" or "inner layer") is used to control the heat sealability of the film, low temperature sealability, easy peelability, or breakage when the package is dropped. It is a layer that is provided to prevent falling bags and provide resistance to falling bags. The first layer contains a first ethylene resin composition (hereinafter sometimes referred to as "ethylene resin composition (Z)").

<Ethylene resin composition (Z)>
The ethylene resin composition (Z) used for the inner layer is a first ethylene-α-olefin copolymer (hereinafter referred to as "ethylene-α-olefin copolymer (G)" or "component (G)"). there is). Ingredients are described below. The ethylene resin composition (Z) can contain the first propylene resin as long as it does not impair the effects of the present invention. 25% by weight, particularly preferably 0 to 10% by weight.

(1) First ethylene-α-olefin copolymer (component (G))
The component (G) used as one component of the ethylene resin composition (Z) is a copolymer of ethylene and α-olefin that satisfies the following conditions (Gi) and (G-ii).
(Gi) Density is in the range of 0.899 to 0.935 g/cm ³ .
(G-ii) Melt flow rate (190° C., 2.16 kg) is in the range of 1 to 10 g/10 minutes.

[(Gi) Density of component (G)]
Component (G) has a density in the range of 0.899 to 0.935 g/cm ³ . By setting the density within this range, good heat resistance, low-temperature impact resistance, flexibility, and transparency required for medical infusion bags can be achieved. Particularly from the viewpoint of maintaining good heat resistance, the density of component (G) is preferably 0.905 g/cm ³ or more, more preferably 0.915 g/cm ³ or more. If necessary, the density of the component (G) can be adjusted to the above range by mixing with a high-density polyethylene resin to maintain heat resistance. Here, the density of each component is a value determined by the pycnometer method based on JIS K7112.

[(G-ii) Melt flow rate of component (G)]
The melt flow rate (190° C., 2.16 kg) of component (G) (hereinafter sometimes referred to as “MFR (G)”) is in the range of 1 to 10 g/10 minutes. When the MFR (G) is 1 g/10 minutes or more, a film with good appearance can be easily obtained without causing interface roughness and surface roughness. When the MFR (G) is 10 g/10 minutes or less, the thickness variation is less likely to occur, resulting in good moldability. MFR(G) preferably ranges from 1.5 to 5.0 g/10 min, more preferably from 1.5 to 3.5 g/10 min. Measurement of MFR (G) is performed by a method based on JIS K7210:1999 Annex A Table 1, Condition D.

• Manufacturing method of component (G) From the viewpoint of transparency, component (G) preferably has a narrow molecular weight distribution in order to control the density within an appropriate range and to control stickiness and bleeding out. Therefore, it is preferable to use a metallocene catalyst capable of narrowing the molecular weight distribution in the production of component (G). As the metallocene catalyst, various known catalysts used for producing ethylene-α-olefin copolymers can be used. Specific examples include metallocene catalysts described in JP-A-58-19309, JP-A-59-95292, JP-A-60-35006, and JP-A-3-163088. . Specific polymerization methods for producing component (G) include a slurry method, a gas phase fluidized bed method and a solution method in the presence of a catalyst, or polymerization at a pressure of 200 kg/ ^cm2 (19.6 MPa) or more A high-pressure bulk polymerization method at a temperature of 100° C. or higher can be used. Preferred manufacturing methods include high pressure bulk polymerization methods.

Component (G) is a copolymer of ethylene and α-olefin, and the compounding ratio of ethylene and α-olefin is not particularly limited as long as the above conditions (Gi) and (G-ii) are satisfied. Any blending ratio, preferably a copolymer containing ethylene as a main component, can be used. Although the type of α-olefin is not particularly limited, α-olefins having 3 to 20 carbon atoms are preferred. Preferred examples of the α-olefin include those having 3 to 20 carbon atoms, such as propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene and 1-octene. Commercially available combined products include AFFINITY and ENGAGE manufactured by Dupont Dow, KERNEL manufactured by Japan Polyethylene Co., Ltd., and EXACT manufactured by ExxonMobil. .

<<Second layer>>
The second layer (hereinafter also referred to as "intermediate layer") is a layer arranged between the first layer and the third layer in the polyolefin resin film. The second layer is a layer containing a second propylene resin composition (hereinafter sometimes referred to as "propylene resin composition (X)").

<Propylene resin composition (X)>
The propylene resin composition (X) used for the intermediate layer contains a second propylene resin (hereinafter sometimes referred to as "propylene resin (A)" or "component (A)"). Ingredients are described below.

(1) Second propylene resin (component (A))
Component (A) used as a component of propylene resin composition (X) is a resin containing a propylene polymer and a propylene-α-olefin random copolymer. Component (A) is required to have high heat resistance, transparency and flexibility. In order to meet these requirements to a high standard, component (A) satisfies the following conditions (Ai) and (A-ii).
(Ai) A propylene-α-olefin random copolymer containing 30 to 70% by weight of a propylene polymer (A1) having a melting peak temperature of 120 to 170° C. in DSC measurement and an α-olefin content of 7 to 30% by weight. It contains 70 to 30% by weight of coalesced (A2).
(A-ii) Melt flow rate (230° C., 2.16 kg) is in the range of 0.5 to 20 g/10 minutes.

[(Ai) propylene polymer (A1) and propylene-α-olefin random copolymer (A2)]
[Melting peak temperature of propylene polymer (A1)]
The propylene polymer (A1) (hereinafter sometimes referred to as "component (A1)") contained in component (A) determines the crystallinity of component (A) and contributes to heat resistance, flexibility, transparency, etc. It is an influencing component. In order to improve the heat resistance of component (A), it is preferable that component (A1) has a high melting peak temperature Tm(A1). The Tm(A1) is in the range of 120 to 170° C. from the viewpoint that thinning during heat sealing can be suppressed while maintaining high flexibility and transparency without impairing heat resistance. Tm(A1) is preferably in the range of 120 to 150°C, more preferably in the range of 125 to 145°C, still more preferably in the range of 125 to 140°C.

[Proportion of component (A1) in component (A)]
The proportion W(A1) of component (A1) in component (A) is a factor that affects the heat resistance of component (A). W(A1) is 70% by weight or less in order to sufficiently exhibit flexibility, transparency and impact resistance. On the other hand, W(A1) is 30% by weight or more in order to maintain heat resistance and eliminate the risk of deformation during the sterilization and sterilization steps. W(A1) preferably ranges from 35 to 65% by weight.

The method for producing the propylene polymer (A1) is not particularly limited as long as the component (A1) satisfies the above conditions, and methods known to those skilled in the art for producing propylene homopolymers or copolymers can be used.

The propylene polymer (A1) may be a propylene homopolymer or a copolymer of propylene as the main component and at least one comonomer, such as a propylene-ethylene copolymer. When component (A1) is a copolymer containing a comonomer other than propylene, the comonomer content is preferably 10% by weight or less relative to the total weight of component (A1). The comonomers used in component (A1) are preferably α-olefins. The α-olefin preferably has 2 or 4 to 20 carbon atoms, more preferably 2 or 4 to 8 carbon atoms. Comonomers are, for example, α-olefins other than propylene such as ethylene, 1-butene, 1-pentene, 1-hexene, 3-methyl-1-butene, 4-methyl-1-pentene, styrene, vinylcyclopentene, vinylcyclohexane , vinyl compounds such as vinyl norbornane, and the like. Two or more of these comonomers may be copolymerized. Preferred comonomers are ethylene, 1-butene or 1-hexene.

[Propylene-α-olefin random copolymer (A2)]
The propylene-α-olefin random copolymer (A2) (hereinafter sometimes referred to as "component (A2)") contained in component (A) enhances the flexibility, impact resistance and transparency of component (A). Formulated for improvement. The α-olefin used in component (A2) may be the same α-olefin as the comonomer used in component (A1). Component (A2) is preferably obtained by copolymerization using a metallocene catalyst.

[α-Olefin Content in Component (A2)]
In general, as the α-olefin content of a propylene-α-olefin random copolymer increases, the crystallinity decreases and the effect of improving flexibility increases. Therefore, the α-olefin content (hereinafter sometimes referred to as α[A2]) in component (A2) is 7% by weight or more. α[A2] is more preferably 8% by weight or more, and still more preferably 10% by weight or more. On the other hand, α[A2] is 30% by weight or less in order to reduce the crystallinity of component (A2) while maintaining transparency. α[A2] is preferably 25% by weight or less, more preferably 20% by weight or less, still more preferably 15% by weight or less, and particularly preferably 14% by weight or less.

[Proportion of component (A2) in component (A)]
The proportion W(A2) of component (A2) in component (A) is 70% by weight or less in order to impart high heat resistance to the polyolefin resin film. Moreover, W(A2) is 30% by weight or more in order to impart flexibility and impact resistance to the polyolefin resin film. W(A2) is preferably in the range of 65-30% by weight.

Here, W(A1) and W(A2) are values determined by temperature rising elution fractionation (TREF), and α[A2] is a value determined by NMR. Further, when the component (A1) is a copolymer with an α-olefin, the α-olefin content of the component (A1) (hereinafter sometimes referred to as “α[A1]”) is α[A2] and requested in the same way. Each value is specifically obtained by the following method.

・Specification of W (A1) and W (A2) by temperature rising elution fractionation (TREF) Method of evaluating crystallinity distribution of propylene-α-olefin random copolymer etc. by temperature rising elution fractionation (TREF) is well known to those skilled in the art, and detailed measurement methods are described, for example, in the following documents.
G. Glockner, J.; Appl. Polym. Sci. : Appl. Polym. Symp. 45, 1-24 (1990)
L. Wild, Adv. Polym. Sci. ; 98, 1-47 (1990)
J. B. P. Soares, A.; E. Hamielec, Polymer; 36, 8, 1639-1654 (1995)

There is a large difference in crystallinity between component (A1) and component (A2), and when both components are produced using a metallocene catalyst, the crystallinity distribution becomes narrow. Intermediate components between (A1) and component (A2) are extremely small, and both components can be accurately separated by TREF.

Specifically, the TREF measurement is performed as follows.
A sample is dissolved in o-dichlorobenzene (containing 0.5 mg/mL dibutylhydroxytoluene (BHT)) at 140° C. to obtain a solution. After introducing this into a TREF column at 140° C., it is cooled to 100° C. at a temperature decrease rate of 8° C./min, subsequently cooled to −15° C. at a temperature decrease rate of 4° C./min, and held for 60 minutes. After that, o-dichlorobenzene at −15° C. (containing 0.5 mg/mL BHT) as a solvent is passed through the column at a flow rate of 1 mL/min, and dissolved in o-dichlorobenzene at −15° C. in the TREF column. The components are eluted for 10 minutes, then the temperature of the column is linearly increased to 140°C at a heating rate of 100°C/hour to obtain an elution curve.

In the obtained elution curve, component (A1) and component (A2) show elution peaks at different temperatures T(A1) and T(A2) due to the difference in crystallinity, and the difference is sufficiently large. Separation is almost possible at temperature T(A3) (={T(A1)+T(A2)}/2). Here, if the integrated amount of the component eluted by T(A3) is defined as W(A2)% by weight, and the integrated amount of the portion eluted at T(A3) or higher is defined as W(A1)% by weight, then W(A2) corresponds to the amount of component (A2), and the integrated amount W(A1) corresponds to the amount of component (A1) with relatively high crystallinity.

An example of equipment and specifications used for measurement is shown below.
(TREF section)
TREF column: 4.3 mmφ x 150 mm stainless steel column Column filler: 100 µm surface-deactivated glass beads Heating method: Aluminum heat block Cooling method: Peltier element (Peltier element is cooled with water)
Temperature distribution: ±0.5°C
Temperature controller: Chino Co., Ltd. digital program controller KP1000 (valve oven)
Heating method: Air bath oven Measurement temperature: 140°C Temperature distribution: ±1°C
Valve: 6-way valve 4-way valve (Sample injection part)
Injection method: loop injection method Injection volume: loop size 0.1 mL
Inlet heating method: Aluminum heat block Measurement temperature: 140°C
(Detection unit)
Detector: Fixed wavelength infrared detector MIRAN 1A manufactured by FOXBORO
Detection wavelength: 3.42 μm
High temperature flow cell: micro flow cell for LC-IR optical path length 1.5 mm
Window shape: 2φ x 4mm oblong synthetic sapphire window plate Temperature at measurement: 140°C
(pump section)
Liquid sending pump: SSC-3461 pump manufactured by Senshu Kagaku [Measurement conditions]
Solvent: o-dichlorobenzene (containing 0.5 mg/mL BHT)
Sample concentration: 5 mg/mL Sample injection volume: 0.1 mL Solvent flow: 1 mL/min

・Specification of α[A1] or α[A2] After separating each component by a temperature-rising column fractionation method using a preparative fractionation device, the α-olefin content of each component α[A1] or α[ A2] is identified. The temperature-rising column fractionation method refers to, for example, the measurement method disclosed in Macromolecules 21 314-319 (1988). Specifically, α[A1] or α[A2] is identified using a method as exemplified below.

- Heated column fractionation A cylindrical column with a diameter of 50 mm and a height of 500 mm is filled with glass bead carriers (80 to 100 mesh) and maintained at 140°C. Next, 200 mL of an o-dichlorobenzene solution (10 mg/mL) of the sample dissolved at 140° C. is introduced into the column. After that, the temperature of the column is cooled down to 0°C at a cooling rate of 10°C/hour. After holding at 0° C. for 1 hour, the column temperature is heated to T(A3) (obtained by TREF measurement) at a heating rate of 10° C./hour and held for 1 hour. The temperature control accuracy of the column through the series of operations shall be ±1°C.
Next, while maintaining the column temperature at T (A3), by flowing 800 mL of o-dichlorobenzene at a temperature T (A3) at a flow rate of 20 mL / min, the components soluble in T (A3) present in the column is eluted and recovered.
Next, raise the temperature of the column to 140°C at a heating rate of 10°C/min, leave it at 140°C for 1 hour, and then flow 800 mL of o-dichlorobenzene as a solvent at 140°C at a flow rate of 20 mL/min. , and temperature T(A3) to elute and recover insoluble components.
The polymer-containing solution obtained by fractionation is concentrated to 20 mL using an evaporator, and then the polymer is precipitated in 5 volumes of methanol. After collecting the precipitated polymer by filtration, it is dried overnight in a vacuum dryer.

・ Measurement of α-olefin content by ¹³ C-NMR The α-olefin content α [A1] or α [A2] of the component obtained by the above fractionation is measured by the ¹³ C-NMR spectrum by the proton complete decoupling method. is obtained by analyzing An example of equipment and specifications used for measurement is shown below.
Model: GSX-400 manufactured by JEOL Ltd. or equivalent device (carbon nuclear resonance frequency of 100 MHz or higher)
Solvent: o-dichlorobenzene/heavy benzene = 4/1 (volume ratio)
Concentration: 100 mg/mL Temperature: 130°C
Pulse angle: 90° Pulse interval: 15 seconds Cumulative count: 5,000 times or more

Attribution of spectra may be performed with reference to, for example, Macromolecules 17 1950 (1984). The assignment of the spectrum measured under the above conditions is shown in Table 1. Symbols such as Sαα in the table follow the notation of Carman et al. (Macromolecules 10 536 (1977)), P represents methyl carbon, S represents methylene carbon, and T represents methine carbon.

Hereinafter, when "P" is the propylene unit in the copolymer chain and "E" is the ethylene unit, six types of triads, PPP, PPE, EPE, PEP, PEE and EEE, can be present in the chain. As described in Macromolecules 15 1150 (1982), etc., the concentration of these triads and the peak intensity of the spectrum are related by the following relational expressions (1) to (6).
[PPP]=k×I(Tββ) (1)
[PPE]=k×I(Tβδ) (2)
[EPE]=k×I(Tδδ) (3)
[PEP]=k×I(Sββ) (4)
[PEE]=k×I(Sβδ) (5)
[EEE]=k×{I(Sδδ)/2+I(Sγδ)/4} (6)
where [ ] indicates the fraction of triads, eg [PPP] is the fraction of PPP triads in all triads.
Therefore, [PPP]+[PPE]+[EPE]+[PEP]+[PEE]+[EEE]=1 (7)
is. Also, k is a constant and I indicates spectral intensity, for example I(Tββ) means the intensity of the peak at 28.7 ppm attributed to Tββ.
Using the relational expressions (1) to (7) above, the fraction of each triad can be obtained, and the α-olefin content can be obtained from the following equation.
α-olefin content (mol%) = ([PEP] + [PEE] + [EEE]) × 100

The propylene-α-olefin random copolymer contains a small amount of propylene heterogeneous bonds (2,1-bonds and/or 1,3-bonds), which gives rise to the minute peaks shown in Table 2.

In order to obtain an accurate α-olefin (ethylene) content, it is necessary to consider the peaks derived from these heterogeneous bonds and include them in the calculation, but it is difficult to completely separate and identify the peaks derived from heterogeneous bonds. Since the amount of heterogeneous bonds is small, the α-olefin content is the same as the analysis of a copolymer produced with a Ziegler-Natta catalyst that does not contain substantially heterogeneous bonds. It is determined by using
The conversion from mol % of the α-olefin content to weight % is performed using the following formula.
α-olefin content (% by weight)
= (MW×X/100)/{MW×X/100+42×(1-X/100)}×100
(Here, MW is the molecular weight of the α-olefin, and X is the α-olefin content in mol%.)

[(A-ii) Melt flow rate of component (A)]
Component (A) has a melt flow rate (230° C., 2.16 kg) (hereinafter sometimes referred to as MFR (A)) in the range of 0.5 to 20 g/10 minutes. MFR(A) is suitable for the following reasons: it can suppress the motor load and tip pressure by reducing the resistance to the rotation of the molding machine screw, and it can suppress roughening of the film surface to keep the appearance good It is 0.5 g/10 minutes or more, preferably 1.0 g/10 minutes or more. On the other hand, the MFR(A) is 20 g/10 minutes or less, preferably 10 g/10 minutes or less, in order to enable stable molding and obtain a uniform film.
MFR (A) is each MFR corresponding to component (A1) and component (A2) (hereinafter sometimes referred to as MFR (A1) and MFR (A2), respectively), and components (A1) and (A2) Determined based on the compounding ratio. In the component (A), if the MFR (A) is in the range of 0.5 to 20 g/10 minutes, the values of MFR (A1) and MFR (A2) are each limited within a range that does not impair the object of the present invention. not. However, it is preferable that the difference between MFR(A1) and MFR(A2) is small in order to reduce the possibility of appearance defects. MFR(A1) and MFR(A2) are both preferably in the range of 0.5 to 20 g/10 min, more preferably both in the range of 1.0 to 10 g/10 min. Here, each MFR value is a value measured under a load of 2.16 kg at 230° C. in accordance with JIS K7210:1999 Annex A Table 1, Condition M.

Further, component (A) preferably satisfies the following condition (A-iii) in addition to the above conditions (Ai) and (A-ii).
(A-iii) Observed in the range of -60 ° C to 20 ° C in the temperature-loss tangent (tan δ) curve obtained by solid viscoelasticity measurement (DMA) measured on a 200 μm thick sheet molded by injection molding. The peak of the tan δ curve representing the glass transition at 0°C shows a single peak.

When the component (A) has a phase separation structure, the glass transition temperature of the amorphous part contained in the component (A1) and the glass transition temperature of the amorphous part contained in the component (A2) are different, so the peak is no longer single. In this case, there arises a problem that the transparency of the film tends to deteriorate. Therefore, it is preferable that the components (A1) and (A2) have approximately the same glass transition temperature, that is, there is one peak representing the glass transition in DMA.

Specifically, solid viscoelasticity measurement (DMA) is performed by applying sinusoidal strain at a specific frequency to a strip-shaped sample piece and detecting the generated stress. A frequency of 1 Hz was used, and the temperature was increased from −60° C. to 20° C. at a rate of 3° C./30 seconds, and from 20° C. or higher, the temperature was increased stepwise at a rate of 3° C./40 seconds. Continue until melted and no longer measurable. Also, it is recommended that the magnitude of distortion is about 0.1 to 0.5%. From the obtained stress, the storage elastic modulus G' and the loss elastic modulus G'' are obtained by a known method, and the loss tangent (= loss elastic modulus/storage elastic modulus) defined by the ratio of these is plotted against temperature. , shows a sharp peak in the temperature range of 0° C. or lower.In general, the peak of the tan δ curve at 0° C. or lower is for observing the glass transition of the amorphous part, and in the present invention, this peak temperature is the glass transition temperature Tg ( °C).
The sample piece for DMA measurement was a strip of 10 mm width×18 mm length×2 mm thickness cut out from a 2 mm thick sheet injection-molded under the following conditions. ARES manufactured by Rheometric Scientific was used as an apparatus. The frequency is 1 Hz. The measurement temperature was raised from -60°C to 20°C at a rate of 3°C/30 seconds, and from 20°C or higher, the temperature was raised stepwise at a rate of 3°C/40 seconds. I measured until Strain was performed in the range of 0.1 to 0.5%.
[Preparation of test piece]
Standard number: JIS-7152 (ISO294-1)
Molding machine: EC-20 injection molding machine manufactured by Toshiba Machine Molding machine setting temperature: 80, 80, 160, 200, 200, 200°C from the bottom of the hopper
Mold temperature: 40°C
Injection speed: 200 mm/sec (speed inside mold cavity)
Holding pressure: 20MPa
Holding pressure time: 40 seconds
Mold shape: flat plate (thickness 2mm width 40mm length 80mm)

- Control method of constituent elements of component (A) Each element of component (A) is controlled as follows, and component (A) is produced so as to satisfy the constituent requirements required for component (A). be able to.
Tm(A1) can be controlled, for example, by appropriately adjusting the amount ratio of propylene supplied to the polymerization reactor and α-olefin as a comonomer. In order to control Tm (A1) to, for example, 120° C. to 170° C., depending on the type of catalyst used, the α-olefin content (α[A1]) of component (A1) should be approximately 0 to A component (A1) having a desired Tm (A1) can be produced by adjusting the content to be in the range of about 10% by weight. The method for measuring α[A1] is as described above.
Further, in order to control α[A2] within a predetermined range, when the component (A2) is produced by a sequential polymerization (multistage polymerization) method, The quantity ratio may be adjusted appropriately. The relationship between the supply ratio and the α-olefin content in the propylene-α-olefin random copolymer obtained varies depending on the type of metallocene catalyst used, but the necessary α[A2] can be adjusted by adjusting the supply ratio. A component (A2) having
For W(A1) and W(A2), in the case of the sequential polymerization method, the ratio of the production amount of the component (A1) in the first step to the production amount of the component (A2) in the second step is changed. can be controlled by As described above, the melt flow rate of component (A) can be adjusted by adjusting the mixing ratio of MFR (A1) and MFR (A2).

・Production method of component (A) Component (A) used in the present invention preferably comprises 30 to 70% by weight of component (A1) in the first step and component (A2) in the second step using a metallocene catalyst. ) in an amount of 70 to 30% by weight, obtained by successive polymerization. As a specific method of the sequential polymerization method, for example, the method described in JP-A-2005-132979 can be used, and the entire contents of the publication are incorporated herein by reference. Moreover, the component (A) may be a blended product of the component (A1) and the component (A2), instead of being a successively polymerized product (multistage polymer).

<Second ethylene-α-olefin copolymer (G)>
The propylene resin composition (X) used for the intermediate layer is a second ethylene-α-olefin copolymer (hereinafter referred to as "ethylene-α-olefin copolymer (G)" or "component (G)" There is also). Ingredients are described below.

(1) Second ethylene-α-olefin copolymer (component (G))
Component (G) used as one component of the second propylene resin is a copolymer of ethylene and α-olefin that satisfies the following conditions (GI) to (G-III).
(GI) is a metallocene-based ethylene-α-olefin copolymer.
(G-II) Density is in the range of 0.880 to 0.920 g/cm ³ .
(G-III) 100% by weight of the second propylene resin composition contains 10 to 40% by weight of the second ethylene-α-olefin copolymer, and the melt flow rate (190°C, 2.16 kg) is preferably It ranges from 1 to 10 g/10 minutes.

[(G-1) Metallocene-based ethylene-α-olefin copolymer]
From the viewpoint of transparency and interfacial strength, the metallocene-based ethylene-α-olefin copolymer preferably has a narrow molecular weight distribution in order to suppress stickiness and bleed-out. Therefore, a metallocene catalyst capable of narrowing the molecular weight distribution is used. . As the metallocene catalyst, various known catalysts used for producing ethylene-α-olefin copolymers can be used. Specific examples include metallocene catalysts described in JP-A-58-19309, JP-A-59-95292, JP-A-60-35006, and JP-A-3-163088. . Specific polymerization methods for producing component (G) include a slurry method, a gas phase fluidized bed method and a solution method in the presence of a catalyst, or polymerization at a pressure of 200 kg/ ^cm2 (19.6 MPa) or more A high-pressure bulk polymerization method at a temperature of 100° C. or higher can be used. Preferred manufacturing methods include high pressure bulk polymerization methods.
The metallocene-based ethylene-α-olefin copolymer is a copolymer of ethylene and α-olefin, and as long as the above conditions (G-II) and (G-III) are satisfied, the blending ratio of ethylene and α-olefin is There are no particular restrictions, and any blending ratio, preferably a copolymer containing ethylene as a main component, can be used. Although the type of α-olefin is not particularly limited, α-olefins having 3 to 20 carbon atoms are preferred. Preferred α-olefins include those having 3 to 20 carbon atoms, such as propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene and 1-octene.

[(G-II) Density of Component (G)]
Component (G) has a density in the range of 0.880 to 0.920 g/cm ³ . By setting the density within this range, the flexibility and transparency required for medical infusion bags can be improved. The density of component (G) is preferably 0.910 g/cm ³ or less, more preferably 0.900 g/cm ³ or less, particularly from the viewpoint of maintaining good transparency. Here, the density of each component is a value determined by the pycnometer method based on JIS K7112.

[(G-III): content of component (G)]
The content of component (G) is 10 to 40% by weight, preferably 15 to 30% by weight, based on 100% by weight of propylene resin composition (X).
When it is 10% by weight or more, the flexibility required for a medical infusion bag is exhibited, and when it is 40% by weight or less, heat resistance is improved and the strength of the interface with the third layer after sterilization treatment is achieved. is easy to improve, and maintains high heat seal strength even before and after sterilization.

[Melt flow rate of component (G)]
The melt flow rate (190° C., 2.16 kg) of component (G) (hereinafter sometimes referred to as “MFR (G)”) is preferably in the range of 1 to 10 g/10 minutes. When the MFR (G) is 1 g/10 minutes or more, a film with good appearance can be easily obtained without causing interface roughness and surface roughness. When the MFR (G) is 10 g/10 minutes or less, the thickness variation is less likely to occur, resulting in good moldability. MFR(G) is more preferably in the range of 1.5 to 5.0 g/10 minutes, still more preferably 1.5 to 3.5 g/10 minutes. Measurement of MFR (G) is performed by a method based on JIS K7210:1999 Annex A Table 1, Condition D.

・Production method of component (G), type of α-olefin and composition It is the same as the -α-olefin copolymer, and can be arbitrarily selected as long as it does not impair the effects of the invention.

<<Third Layer>>
The third layer (hereinafter also referred to as "outer layer") is a layer arranged on the outside of the package when the polyolefin resin film is used as the package. The material of the outer layer is not particularly limited to polypropylene resin, as long as it does not impair the heat resistance and transparency of the polyolefin resin film. It can be blended with α-olefin copolymers. Among these, it is preferably formed from a propylene resin composition (Y) containing a styrene elastomer (hereinafter sometimes referred to as "styrene elastomer (S)" or "component (S)").

It is important that the propylene resin composition (Y) preferably used as the outer layer of the polyolefin resin film has excellent transparency and heat resistance. In order to obtain transparency as a film, not only the intermediate layer but also the outer layer must be made transparent. In addition, it is preferable not to be deformed by heat treatment such as sterilization and sterilization, and not to adhere to the heat seal bar in heat sealing which is secondary processing.

In order to meet these requirements at a high level, the propylene resin composition (Y) preferably used for the outer layer is a third propylene resin (hereinafter referred to as "propylene Also referred to as "resin (E)" or "component (E)").
(Ei) The melting peak temperature in DSC measurement is in the range of 150 to 170°C.
(E-ii) Melt flow rate (230° C., 2.16 kg) is in the range of 2 to 20 g/10 min.

[Melting peak temperature of (Ei) component (E)]
The melting peak temperature Tm(E) of component (E) is in the range of 150-170°C. When Tm(E) is 150° C. or higher, sufficient heat resistance is obtained, and the polypropylene resin film is less likely to fuse to the heat seal bar during heat sealing. If Tm(E) is 170° C. or less, industrial production is easy. Tm(E) is preferably in the range of 155-170°C, more preferably in the range of 158-168°C.

[(E-ii) Melt flow rate of component (E)]
It is important for component (E) to have moderate fluidity in order to obtain easy moldability that does not cause interface roughness or surface roughness during lamination and thickness fluctuations. The melt flow rate (230° C., 2.16 kg) of a certain component (E) (hereinafter also referred to as MFR (E)) is in the range of 2 to 20 g/10 minutes. If the MFR(E) is 2 g/10 minutes or more, a film with good appearance can be obtained without causing interface roughness or surface roughness. On the other hand, when the MFR(E) is 20 g/10 min or less, the thickness does not fluctuate and the moldability can be maintained. The MFR(E) is preferably in the range of 2-15 g/10 min, more preferably in the range of 4-15 g/10 min. Here, the MFR is a value measured at 230° C. and a load of 2.16 kg in accordance with JIS K7210:1999 Annex A Table 1, Condition M.

The propylene resin (E) may be a propylene homopolymer, a random copolymer with another α-olefin, or another α- It may be a block copolymer with an olefin. Examples of the α-olefin are the same as those listed above for the component (A).

Component (E) may be produced by any method as long as it satisfies the above conditions (Ei) and (E-ii). The propylene resin (E) may be a composition comprising a propylene polymer (E1) and a propylene-ethylene random copolymer (E2). The coalescence (E1) and the propylene-ethylene random copolymer (E2) may be produced by mixing using a mixing apparatus, and the propylene polymer (E1) is produced by a sequential polymerization (multistage polymerization) method, Subsequently, the propylene-ethylene random copolymer (E2) may be produced in the presence of the propylene polymer (E1) to continuously produce the propylene resin (E).

Component (E) can also be appropriately selected from commercially available products and used. Commercially available products include NOVATEC PP (trade name) manufactured by Japan Polypropylene Corporation. A grade that satisfies the conditions (Ei) and (E-ii) in use may be appropriately selected.

・ Modifier (S)
An elastomer component (S) may be added to the propylene resin composition (Y) in order to further impart low-temperature impact resistance. Examples of elastomer components that can be blended into the outer layer of the polyolefin resin film include styrene elastomers. The styrene content of the styrene-based elastomer is preferably in the range of 1 to 20% by weight. If the styrene content is too high, the compatibility with polypropylene is lowered and the transparency is deteriorated.

The styrene-based elastomer can be appropriately selected and used from commercially available ones. For example, as a hydrogenated product of a styrene-butadiene block copolymer, Kraton Polymer Japan Co., Ltd. under the trade name of "Kraton G", and Asahi Chemical Industry Co., Ltd. under the trade name of "Tuftec", a styrene-isoprene block copolymer. As a hydrogenated polymer from Kuraray Co., Ltd., under the trade name of "Septon", and as a hydrogenated styrene-vinylated polyisoprene block copolymer from Kuraray Co., Ltd., under the trade name of "Hybler", styrene- It is sold as a hydrogenated product of butadiene random copolymer under the trade name of "Dynaron" by JSR Corporation. MFR should be selected. Further, the propylene resin composition (Y) may further contain other components within a range that does not significantly impair the effects of the present invention.

Proportion of each component in propylene resin composition (Y) When the propylene resin composition (Y) contains the component (S), the proportion of the component (E) in the outer layer is 70% of the total weight of the outer layer. The content of component (S) in the outer layer is preferably in the range of 1 to 30% by weight with respect to the total weight of the outer layer. More preferably, the content of component (E) is in the range of 75-95% by weight and the content of component (S) is in the range of 5-25% by weight. When the content of component (E) is 70% by weight or more, that is, the content of component (S) is 30% by weight or less, sufficient heat resistance can be obtained, and the risk of deformation occurring in the heat treatment step is small. Become. When the content of component (E) is 99% by weight or less, that is, when the content of component (S) is 1% by weight or more, the effect of imparting low-temperature impact resistance can be obtained.

<Additional component (additive)>
Each of the propylene resin composition (X), the propylene resin composition (Y) and the ethylene resin composition (Z) used for the intermediate layer, outer layer and inner layer in the polyolefin resin film is bleed out in order to be suitably used as a film. Any additive can be added as long as it does not significantly impair the effects of the present invention such as generation of Such optional components include antioxidants, crystal nucleating agents, clarifying agents, lubricants, antiblocking agents, antistatic agents, antifogging agents, neutralizers, and metal deactivators that are commonly used in polyolefin resin materials. agents, colorants, dispersants, peroxides, fillers, optical brighteners, and the like. Various additives are described in detail below. Furthermore, an elastomer can be blended as a component that imparts flexibility within the range that does not significantly impair the effects of the present invention.

(a) Antioxidant As the antioxidant, antioxidants known to those skilled in the art can be used, and examples thereof include phenol antioxidants, phosphorus antioxidants, sulfur antioxidants, and the like.
Specific examples of phenolic antioxidants include tris-(3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate, 1,1,3-tris(2-methyl-4-hydroxy-5- t-butylphenyl)butane, octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, pentaerythrityl-tetrakis{3-(3,5-di-t-butyl-4- hydroxyphenyl)propionate}, 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, 3,9-bis[2-{3- (3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy}-1,1-dimethylethyl]-2,4,8,10-tetraoxaspiro[5,5]undecane, 1,3, 5-tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanurate and the like can be mentioned.

Specific examples of phosphorus antioxidants include tris(mixed, mono- and dinonylphenyl) phosphite, tris(2,4-di-t-butylphenyl) phosphite, 4,4'-butylidenebis(3- methyl-6-t-butylphenyl-di-tridecyl)phosphite, 1,1,3-tris(2-methyl-4-di-tridecylphosphite-5-t-butylphenyl)butane, bis(2, 4-di-t-butylphenyl)pentaerythritol-di-phosphite, tetrakis(2,4-di-t-butylphenyl)-4,4'-biphenylenediphosphonite, tetrakis(2,4-di-t -Butyl-5-methylphenyl)-4,4'-biphenylenediphosphonite, bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol-di-phosphite and the like.
Specific examples of sulfur antioxidants include di-stearyl-thio-di-propionate, di-myristyl-thio-di-propionate, pentaerythritol-tetrakis-(3-lauryl-thio-propionate) and the like. can.
These antioxidants can be used singly or in combination of two or more as long as the effects of the present invention are not impaired.

The amount of the antioxidant compounded is 0.01 to 1.0 parts by weight, preferably 0.02 to 0.5 parts by weight, more preferably 0.05 to 0.5 parts by weight, per 100 parts by weight of each resin composition. 1 part by weight. By setting the blending amount within the above range, the effect of thermal stability can be obtained, and the causes of fish eyes such as deterioration that occurs during resin production and scorching, and the antioxidant itself becoming a foreign substance are eliminated. can do.

(b) Anti-blocking agent As the anti-blocking agent, both inorganic and organic anti-blocking agents can be used.
Specific examples of antiblocking agents include, for example, inorganic compounds such as synthetic or natural silica (silicon dioxide), magnesium silicate, aluminosilicate, talc, zeolite, aluminum borate, calcium carbonate, calcium sulfate, barium sulfate, and calcium phosphate. etc. Organic materials include polymethylmethacrylate, polymethylsilsesquioxane (silicone), polyamide, polytetrafluoroethylene, epoxy resin, polyester resin, melamine resin, benzoguanamine/formaldehyde resin, urea resin (urea resin), and phenol. A resin etc. are mentioned. Synthetic silica and polymethyl methacrylate are particularly preferred in view of the balance of dispersibility, transparency, blocking resistance and scratch resistance.
A surface-treated anti-blocking agent may also be used. Examples of surface-treating agents include surfactants, metal soaps, organic acids such as acrylic acid, oxalic acid, citric acid, and tartaric acid, higher alcohols, esters, Silicones, fluororesins, silane coupling agents, condensed phosphates such as sodium hexametaphosphate, sodium pyrophosphate, sodium tripolyphosphate, and sodium trimetaphosphate can be used. is preferred. The treatment method is not particularly limited, and known methods such as surface spraying and immersion can be employed.
The particles of the anti-blocking agent may have any shape, and may be spherical, angular, columnar, acicular, plate-like, amorphous, or any other shape.
The particle size of the antiblocking agent is 1 to 7 μm, preferably 1 to 5 μm, more preferably 1 to 4 μm in average particle size. By setting the average particle size to 1 μm or more, it is possible to maintain good slipperiness and openability of the resulting film. On the other hand, when the thickness is 7 μm or less, transparency and scratch resistance can be maintained. Here, the average particle size is a value measured by a Coulter counter, and methods for defining the average particle size when the shape is angular, columnar, needle-like, or plate-like are known to those skilled in the art.
These antiblocking agents can be used singly or in combination of two or more as long as the effects of the present invention are not impaired.

When the anti-blocking agent is blended, the blending amount is 0.01 to 1.0 parts by weight, preferably 0.05 to 0.7 parts by weight, more preferably 0.05 to 0.7 parts by weight, per 100 parts by weight of each resin composition. 1 to 0.5 parts by weight. By setting the blending amount to 0.01 part by weight or more, the anti-blocking property, slipperiness, and openability of the film tend to be improved. By setting the blending amount to 1.0 part by weight or less, it is possible to maintain the transparency of the film and eliminate the cause of fisheyes, such as foreign substances themselves.

(c) Slip agents Slip agents include monoamides, substituted amides, bisamides and the like, and can be used alone or in combination of two or more.
Specific examples of monoamides include saturated fatty acid monoamides such as lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and hydroxystearic acid amide. Examples of unsaturated fatty acid monoamides include oleic acid amide, erucic acid amide, and ricinoleic acid amide.
Specific examples of substituted amides include N-stearyl stearamide, N-oleyl oleamide, N-stearyl oleamide, N-oleyl stearamide, N-stearyl erucamide, and N-oleyl palmitamide. etc.
Specific examples of bisamides include saturated fatty acid bisamides such as methylenebisstearic acid amide, ethylenebiscapric acid amide, ethylenebislauric acid amide, ethylenebisstearic acid amide, ethylenebisisostearic acid amide, ethylenebishydroxystearic acid amide, Ethylenebisbehenic acid amide, hexamethylenebisstearic acid amide, hexamethylenebisbehenic acid amide, hexamethylenebishydroxystearic acid amide, N,N'-distearyladipic acid amide, N,N'-distearyl and sebacic acid amide. The unsaturated fatty acid bisamides include ethylenebisoleic acid amide, hexamethylenebisoleic acid amide, N,N'-dioleyladipic acid amide, N,N'-dioleylsebacic acid amide and the like. Examples of aromatic bisamides include m-xylylenebisstearic acid amide and N,N'-distearylisophthalic acid amide.
Among these fatty acid amides, oleic acid amide, erucic acid amide, and behenic acid amide are particularly preferably used.

When the slip agent is blended, the blending amount is 0.01 to 1.0 parts by weight, preferably 0.05 to 0.7 parts by weight, more preferably 0 parts by weight, per 100 parts by weight of each resin composition. .1 to 0.4 parts by weight. By making it 0.01 part by weight or more, the opening property and slipperiness tend to be improved. When the content is 1.0 parts by weight or less, the slipping agent is prevented from extruding excessively, and bleeding on the film surface is less likely to deteriorate the transparency.

(d) Nucleating agent Specific examples of the nucleating agent include sodium-2,2′-methylene-bis(4,6-di-t-butylphenyl)phosphate, talc, 1,3,2,4-di( Sorbitol compounds such as p-methylbenzylidene) sorbitol, hydroxy-di(t-butylbenzoate) aluminum, aluminum hydroxy-2,2'-methylene-bis(4,6-di-t-butylphenyl) phosphate and an aliphatic monocarboxylic acid lithium salt mixture having 8 to 20 carbon atoms (manufactured by ADEKA Corporation, trade name NA21).
The amount of the nucleating agent to be blended is 0.0005 to 0.5 parts by weight, preferably 0.001 to 0.1 parts by weight, more preferably 0.001 to 0.1 parts by weight, based on 100 parts by weight of each resin composition. 0.005 to 0.05 parts by weight. By setting it to 0.0005 parts by weight or more, the effect as a nucleating agent can be sufficiently obtained. By setting the amount to 0.5 parts by weight or less, it is possible to eliminate the cause of fish eyes, such as foreign substances themselves.

(e) Neutralizing agent Specific examples of the neutralizing agent include calcium stearate, zinc stearate, hydrotalcite, and Mizukalac (manufactured by Mizusawa Chemical Industry Co., Ltd.).
When the neutralizing agent is blended, the blending amount is 0.01 to 1.0 parts by weight, preferably 0.02 to 0.5 parts by weight, more preferably 0.02 to 0.5 parts by weight, per 100 parts by weight of each resin composition. 05 to 0.1 parts by weight. By setting the blending amount within the above range, a sufficient effect as a neutralizing agent can be obtained, and the causes of fish eyes such as scraping out deteriorated resin inside the extruder and itself becoming a foreign substance can be eliminated. can be done.

(f) Light stabilizer As a light stabilizer, a hindered amine stabilizer is preferably used, and all hydrogens bonded to the carbon atoms at the 2- and 6-positions of a conventionally known piperidine are substituted with methyl groups. is used without particular limitation.
Specific examples include a polycondensation product of dimethyl succinate and 1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidine, tetrakis(1,2,2,6,6 -pentamethyl-4-piperidyl) 1,2,3,4-butanetetracarboxylate, bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, N,N-bis(3-aminopropyl) ) Ethylenediamine 2,4-bis[N-butyl-N-(1,2,2,6,6-pentamethyl-4-piperidyl)amino]-6-chloro-1,3,5-triazine condensate, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, poly[{6-(1,1,3,3-tetramethylbutyl)imino-1,3,5-triazine-2,4- diyl} {(2,2,6,6-tetramethyl-4-piperidyl)imino} hexamethylene {2,2,6,6-tetramethyl-4-piperidyl}imino], poly[(6-morpholino-s -triazine-2,4-diyl)[(2,2,6,6-tetramethyl-4-piperidyl)imino]hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl)imino}] etc. can be mentioned.
These hindered amine stabilizers may be used singly or in combination of two or more as long as the effects of the present invention are not impaired.

When the hindered amine stabilizer is blended, the blending amount is 0.005 to 2 parts by weight, preferably 0.01 to 1 part by weight, more preferably 0.05 to 0 parts by weight, per 100 parts by weight of each resin composition. .5 parts by weight. By setting the amount of the hindered amine stabilizer to 0.005 parts by weight or more, the effect of improving stability such as heat resistance and aging resistance can be obtained. It is possible to eliminate the cause of fisheye such as becoming.

(g) Antistatic agent The antistatic agent can be used without particular limitation as long as it is conventionally known as an antistatic agent or an antistatic agent. Examples include surfactants, nonionic surfactants, amphoteric surfactants, and the like.
Examples of the anionic surfactant include carboxylates such as fatty acids or rosin acid soaps, N-acyl carboxylates, ether carboxylates, and fatty acid amine salts; sulfosuccinates, ester sulfonates, N-acylsulfonic acids Sulfonates such as salts; Sulfuric acid ester salts such as sulfated oils, sulfates, alkyl sulfates, alkyl polyoxyethylene sulfates, ether sulfates, and amide sulfates; alkyl phosphates, alkyl polyoxyethylene phosphates salts, phosphate ester salts such as phosphate ether salts and phosphate amide salts, and the like.

Cationic surfactants include amine salts such as alkylamine salts; alkyltrimethylammonium chloride, alkylbenzyldimethylammonium chloride, alkyldihydroxyethylmethylammonium chloride, dialkyldimethylammonium chloride, tetraalkylammonium salts, N,N-di( Polyoxyethylene) quaternary ammonium salts such as dialkylammonium salts, salts of N-alkylalkanamid ammonium; 1-hydroxyethyl-2-alkyl-2-imidazoline, 1-hydroxyethyl-1-alkyl-2-alkyl- alkylimidazoline derivatives such as 2-imidazoline; imidazolinium salts, pyridinium salts, isoquinolinium salts and the like.

Nonionic surfactants include ether types such as alkyl polyoxyethylene ethers and p-alkylphenyl polyoxyethylene ethers; Ether ester type; ester type such as fatty acid polyoxyethylene ester, monoglyceride, diglyceride, sorbitan ester, sucrose ester, dihydric alcohol ester, borate ester; dialcohol alkylamine, dialcohol alkylamine ester, fatty acid alkanolamide, N , N-di(polyoxyethylene)alkaneamides, alkanolamine esters, N,N-di(polyoxyethylene)alkaneamines, amine oxides, and nitrogen-containing types such as alkylpolyethyleneimines.

Amphoteric surfactants include amino acid forms such as monoaminocarboxylic acids and polyaminocarboxylic acids; N-alkyl-β-alanine forms such as N-alkylaminopropionates and N,N-di(carboxyethyl)alkylamine salts. betaine forms such as N-alkylbetaines, N-alkylamidobetaines, N-alkylsulfobetaines, N,N-di(polyoxyethylene)alkylbetaines, imidazolinium betaine; 1-carboxymethyl-1-hydroxy-1 -hydroxyethyl-2-alkyl-2-imidazoline, 1-sulfoethyl-2-alkyl-2-imidazoline and other alkyl imidazoline derivatives.

Among these surfactants, nonionic surfactants and amphoteric surfactants are preferred, and among them ester-type or nitrogen-containing non-ionic surfactants such as monoglycerides, diglycerides, boric acid esters, dialcoholalkylamines, dialcoholalkylamine esters and amides. Ionic surfactants; betaine forms of amphoteric surfactants are preferred.

As the antistatic agent, a commercially available product can be used. diethanolamine), Electrostripper EA (manufactured by Kao Corporation, trademark, lauryl diethanolamine), Electrostripper EA-7 (manufactured by Kao Corporation, trademark, polyoxyethylene laurylamine caprylic ester), Denon 331P (Marubishi Oil Chemical ( Co., Ltd., trademark, stearyl diethanolamine monostearate), Denon 310 (manufactured by Marubishi Yuka Co., Ltd., trademark, alkyldiethanolamine fatty acid monoester), Resist PE-139 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trademark , stearic acid mono&diglyceride boric acid ester), Chemistat 4700 (manufactured by Sanyo Kasei Co., Ltd., trademark, alkyldimethyl betaine), Rheostat S (manufactured by Lion Corporation, trademark, alkyldiethanolamide), and the like.

When the antistatic agent is blended, the blending amount is 0.01 to 2 parts by weight, preferably 0.05 to 1 part by weight, more preferably 0.1 to 0.1 part by weight, per 100 parts by weight of each resin composition. 8 parts by weight, more preferably 0.2 to 0.5 parts by weight. These antistatic agents can be used singly or in combination of two or more as long as the effects of the present invention are not impaired. By setting the amount of the antistatic agent to 0.01 part by weight or more, the surface specific resistance can be reduced to prevent troubles due to electrification. By setting the amount to 2 parts by weight or less, dusting due to bleeding is less likely to occur on the film surface.

<<Other Layers>>
The first, second and third layers constituting the polyolefin resin film are laminated in order, but an arbitrary layer such as an adhesive layer may be additionally provided between each layer. However, from the viewpoint of cost, it is preferable that the first layer and the second layer are adjacent to each other. As the material used for the adhesive layer, any material known to those skilled in the art can be used as long as it does not impair the effects of the present invention, and it is provided at the desired position of the film by a method known to those skilled in the art.

<Method for producing resin composition constituting each layer of polyolefin resin film>
The propylene resin composition (X) constituting the intermediate layer in the polyolefin resin film comprises the above-described propylene resin (A), ethylene-α-olefin copolymer (G), and other additional components mixed in a Henschel mixer, V It can be obtained by mixing with a blender, ribbon blender, tumbler blender, etc., and kneading with a kneader such as a single-screw extruder, a multi-screw extruder, a kneader, or a Banbury mixer, if necessary. The propylene resin composition (Y) and the ethylene resin composition (Z), which constitute the outer layer or inner layer of the polyolefin resin film, are also obtained by mixing and kneading the above components by the above method. Each component may be mixed at the same time, or a part thereof may be used as a masterbatch and then mixed and kneaded.

<<<polyolefin resin film>>>
The polyolefin resin film of the present invention preferably has a thickness in the range of 0.01 mm to 1.0 mm. The ratio of the thickness of the intermediate layer to the thickness of the entire film is preferably in the range of 50-96, more preferably in the range of 60-90. By setting the thickness ratio of the intermediate layer to 50 or more, flexibility and impact resistance tend to be improved, and by setting it to 96 or less, heat resistance tends to be improved.
The ratio of the thickness of the outer layer of the polyolefin resin film is preferably in the range of 2 to 48, more preferably in the range of 5 to 30, when the thickness of the entire film is 100.
The thickness ratio of the inner layer of the polyolefin resin film is preferably in the range of 2 to 48, more preferably in the range of 5 to 30, when the thickness of the entire film is 100.

The polyolefin resin film of the present invention is characterized by having excellent flexibility even after heat treatment, and preferably has a tensile modulus of elasticity of 300 MPa or less, which is a measure of flexibility. When the tensile modulus is 300 MPa or less, more preferably 260 MPa or less, and still more preferably 240 MPa or less, there is no stiff feeling, so there are advantages such as good tactile sensation and excellent drainage when used as an infusion bag.

The polyolefin resin film of the present invention has an internal haze, which is a measure of transparency, of preferably 8% or less, more preferably 7% or less, and even more preferably 6% or less after heat treatment. By setting the internal haze within the above range, the content can be clearly seen, and it is very excellent in that it is possible to check whether or not foreign matter is contained in the content.

The polyolefin resin film of the present invention is excellent in impact resistance, especially at low temperatures such as 5°C. It has excellent impact resistance that does not break even if it is dropped 10 times in succession, and it is excellent in that it can be used as a product without breaking even if it is dropped during transportation or storage.

The polyolefin resin film of the present invention has such excellent heat resistance that it does not undergo deformation even when subjected to heat treatment at around 121°C. A deformed product has a poor appearance and a reduced product value, and cannot be used as a product. In addition, the polyolefin resin film of the present invention has excellent cleanness, and the material used for the second layer, which constitutes the majority of the film, is a low-molecular-weight component and a low-regular component that may contaminate the film. is extremely low. In addition, the laminated body has excellent interlaminar strength even after heat treatment at 121° C., and the reduction in strength is extremely small compared to before and after sterilization.

The polyolefin resin film of the present invention can be produced by a known film production method. For example, it is extrusion molding using a T die or a circular die, and more specifically, it can be manufactured by known techniques such as a T die casting method, a water-cooled inflation method, an air-cooled inflation method, and the like. Among them, the water-cooled inflation method and the water-cooled deflation method, in which a resin melted and kneaded in an extruder is extruded from a circular die and cooled by being brought into contact with a coolant such as water to produce a film, is a film with good transparency. can be manufactured. Such a method is the preferred manufacturing method for the film.
Specifically, the water cooling inflation method is a method including the following steps:
(1) Melting the olefin resin compositions (X), (Y) and (Z) for each layer respectively in each extruder;
(2) A state in which molten propylene resin composition (X), propylene resin composition (Y) and ethylene resin composition (Z) for each layer are laminated from a ring-shaped co-extrusion multilayer circular die connected to each extruder. pushing out with;
(3) The resin melted and extruded into a tubular shape is blown with air to expand and slowly cooled with an air ring; and (4) The resin is rapidly cooled by contact with cooling water to form a polyolefin resin film. to get
The clearance (lip width) of the melt extruded portion of the circular die is preferably in the range of 0.5 to 3.0 mm, more preferably in the range of 0.7 to 2.0 mm. The molding temperature is 180-280°C, preferably 190-230°C. The blow ratio ranges from 0.5 to 2.0, preferably from 0.7 to 1.5. The film forming speed is 5 to 50 m/min, preferably 7 to 30 m/min. For water cooling, for example, a sizing link or a water tank type water cooling ring is used. The temperature of the cooling water is 10-60°C, preferably 10-40°C. The present invention includes a method for producing a polyolefin resin film by a water-cooled inflation method including the steps described above.

As described above, the polyolefin resin film of the present invention is excellent in flexibility, transparency, impact resistance, heat resistance, and cleanliness, and can suppress deterioration of transparency due to appearance defects such as uneven thickness and interface roughness. The prepylene resin layer and the ethylene resin layer are difficult to separate from each other even in heat treatment processes such as sterilization and sterilization, and therefore, it is suitable as a package for heat treatment. The package for heat treatment of the present invention includes a bag-like container made of the polyolefin resin film. The package may also have injection parts such as spouts, discharge ports, and injection ports fused to the container so that the contents of the package can be poured out. Furthermore, depending on the use of the package, for example, a hole for hanging the package for drip infusion, a notch for opening the package, and the like may be provided in the periphery. The storage part of the package for heat treatment of the present invention is formed by, for example, thermocompression bonding of both ends of a cylindrically formed film, or thermocompression bonding of two polyolefin resin films stacked so that the inner layers are in contact with each other. obtained by At this time, the injection part serving as the outlet for the content may be formed by heat-sealing at the same time as the housing part is molded, or the formation of the housing part and the injection part may be performed in separate processes. be.
Examples of heat-treated packages include retort packages, blood bags, and infusion bags as medical containers such as bags for artificial dialysis. A package for heat treatment, such as an infusion bag, containing the polyolefin resin film of the present invention is also an aspect of the present invention.

In the following, in order to explain the present invention more specifically and clearly, the present invention will be described in comparison with examples and comparative examples, and the rationality and significance of the requirements of the configuration of the present invention will be demonstrated. The invention is not limited to these examples. Physical property measurement methods, property evaluation methods, and resin materials used in Examples and Comparative Examples are as follows.

1. Measurement method of resin physical properties (a) Melt flow rate:
The melt flow rate of the propylene resin composition or styrene-based elastomer was measured according to JIS K7210:1999 Annex A Table 1, Condition M, test temperature: 230 ° C., nominal load: 2.16 kg, die shape: diameter 2.095 mm length Measured at a height of 8.00 mm.
The melt flow rate of the ethylene-α-olefin copolymer was measured according to JIS K7210:1999 Annex A Table 1, Condition D, test temperature: 190 ° C., nominal load: 2.16 kg, die shape: diameter 2.095 mm length. Measured at a height of 8.00 mm.
(b) Density:
It was measured by the pycnometer method according to JIS K7112.
(c) Melting peak temperature:
Using a DSC manufactured by TA Instruments, 5.0 mg of a sample was taken, held at 200° C. for 5 minutes, crystallized to 40° C. at a temperature drop rate of 10° C./min, and further heated at a temperature increase rate of 10° C./min. The melting peak temperature was measured when melting at .
(d) Measurement of tan δ peak temperature As a sample, a strip having a width of 10 mm, a length of 18 mm, and a thickness of 2 mm was cut out from a 2 mm-thick sheet injection-molded under the following conditions. ARES manufactured by Rheometric Scientific was used as an apparatus. The frequency is 1 Hz. The measurement temperature was raised from -60°C to 20°C at a rate of 3°C/30 seconds, and from 20°C or higher, the temperature was raised stepwise at a rate of 3°C/40 seconds. I measured until Strain was performed in the range of 0.1 to 0.5%.
[Preparation of test piece]
Standard number: JIS-7152 (ISO294-1)
Molding machine: EC-20 injection molding machine manufactured by Toshiba Machine Molding machine setting temperature: 80, 80, 160, 200, 200, 200°C from the bottom of the hopper
Mold temperature: 40°C
Injection speed: 200 mm/sec (speed inside mold cavity)
Holding pressure: 20MPa
Holding pressure time: 40 seconds
Mold shape: flat plate (thickness 2mm width 40mm length 80mm)
(e) W(A1), W(A2), α[A1] and α[A2] were measured by the method described above.

2. Film evaluation method (1) Heat resistance A cylindrical laminated film was cut into a size of 210 mm in the direction of flow, and one of the cut pieces was heat-sealed using an impulse sealer to form a bag. Then, 250 ml of water was filled therein, and the other side was heat-sealed using an impulse sealer. Sealing was performed so that the distance between the heat seals was 200 mm. The sample bag thus obtained is placed in a high-temperature and high-pressure cooking sterilization tester (manufactured by Hisaka Seisakusho, model RCS-40RTGN), pressurized, the atmospheric temperature is raised to 121 ° C., and the temperature was held for 30 minutes. After cooling to about 40° C., the sample bag was removed from the tester. (Hereinafter, this sterilized film (sample bag) is sometimes referred to as a heat-treated laminated film.)
The heat resistance of the heat-treated film was evaluated according to the following criteria.
×: Unusable due to deformation, wrinkles, and inner surface fusion ○: No deformation, wrinkles, and inner surface fusion; Described as appearance.
(2) Transparency (Internal HAZE):
After the heat treatment, both surfaces of the laminated film were brought into close contact with a slide glass using liquid paraffin, and measured with a haze meter in accordance with JIS K7136-2000. The smaller the obtained value, the better the transparency, and if this value is 8% or less, it is easy to check the contents, and for example, it is excellent in safety in medical applications, and 7% or less is preferable. % or less is particularly preferred.
(3) Tensile modulus:
In accordance with JIS K-7127-1989, the tensile modulus in the machine direction (MD) of the heat-treated laminated film was measured under the following conditions. The smaller the obtained value, the more excellent the flexibility. If this value is 300 MPa or less, it is excellent in terms of obtaining a high-class feeling with a good touch, and 260 MPa or less is preferable, and 240 MPa or less is particularly. preferable.
Sample length: 150mm
Sample width: 15mm
Distance between chucks: 100mm
Crosshead speed: 1mm/min

(4) Measurement of peel strength after heat sealing:
(i) Heat-sealing conditions The resulting laminated film was cut into a size of 100 mm in the direction of flow of the cylindrical shape, and one of the cut pieces was heat-sealed between the inner layer surfaces of the laminate (heat-sealing conditions: pressure 3.4 kgf). / cm ² (0.33 MPa), time 1.5 seconds, heat sealing is performed for each sample in the range of 100 ° C. to 160 ° C. in increments of 5 ° C.), 23 ° C., 50% RH atmosphere for 24 hours. A laminate film to be conditioned and a laminate film heat-treated with water in the same manner as in the evaluation of heat resistance were produced.
(ii) Peeling test The film after heat sealing is cut into strips with a width of 10 mm in the flow direction to make a sample for testing, and the seal part is opened at 180 degrees with the seal part in the center (manufactured by Orientec Co., Ltd.) and pulled at a peeling speed of 500 mm/min until the seal portion or the base film broke, and the maximum load during that time was determined.
The higher the numerical value obtained, the more strongly the film adheres, indicating that the film can be heat-sealed with high strength. If this numerical value is 30 N/10 mm or more, it can be sufficiently used for heavy-weight packaging applications.
In addition, regardless of the heat seal strength, the presence or absence of interfacial peeling was confirmed during the peeling test, and changes before and after sterilization were also evaluated. If interfacial detachment occurs, the contents may leak, and it is conceivable that foreign matter may be mixed into the product, lowering the safety of the product.

(5) Appearance after secondary processing:
The portion of the laminated film after the heat sealing that was in contact with the heat sealing bar was visually observed to judge whether the appearance was good or bad. If the appearance is bad, it is thought that the laminated film has become thin and thin due to heat sealing, and the laminated film is damaged from the thin part, and there is a risk of contents leakage or contamination inside. It is believed that there is.
○: State where the heat seal bar contact part is smooth and the surface is not rough ×: State where the heat seal bar contact part is uneven and the surface is rough (6) Drop bag impact test:
One side of the cylindrical molded body obtained during the production of the laminated film is cut into a folded width of 92 mm and a length of 210 mm. After that, 250 ml of water was filled therein, and the other opening was temporarily sealed with an impulse sealer, and then heat-sealed under the above heat-sealing conditions to form a water-sealed bag containing water. After the water-filled bag was conditioned in an atmosphere of 5°C for 7 days, the obtained water-filled bag was dropped from a height of 2 m 10 times in succession, and the survival rate of the bag that did not break was evaluated by N = 5. evaluated.

3. Resin used (I) Propylene-based polymer (1) Propylene resin composition (X)
As the component (X) of the intermediate layer, a propylene resin PP (A-1) obtained by a sequential polymerization method according to Production Example (A-1) below was used.

[Production Example (A-1): Production of PP (A-1)]
(i) Preparation of prepolymerization catalyst (chemical treatment of silicate)
3.75 L of distilled water and then 2.5 kg of concentrated sulfuric acid (96%) were slowly added to a 10-liter separable glass flask equipped with a stirring blade. At 50 ° C., 1 kg of montmorillonite (trade name “Benclay SL” manufactured by Mizusawa Chemical Co., Ltd., average particle size = 25 μm, particle size distribution = 10 to 60 μm) was dispersed, the temperature was raised to 90 ° C., and the temperature was maintained for 6.5 hours. maintained. After cooling to 50° C., the slurry was filtered under reduced pressure to collect a cake. The cake was reslurried by adding 7 liters of distilled water and filtered. This washing operation was carried out until the pH of the washing liquid (filtrate) exceeded 3.5. The collected cake was dried overnight at 110° C. under a nitrogen atmosphere. The weight after drying was 707 g.

(Drying of silicate)
The previously chemically treated silicate was dried using a kiln dryer. The specifications and drying conditions of the dryer are as follows.
Rotating cylinder: Cylindrical, inner diameter 50 mm, heating zone 550 mm (electric furnace)
Rotation speed with scraping blade: 2 rpm Tilt angle: 20/520
Feed rate of silicate: 2.5 g/min Gas flow rate: Nitrogen 96 L/h Countercurrent drying temperature: 200°C (powder temperature)

(Preparation of catalyst)
A 16-liter autoclave equipped with agitation and temperature controls was thoroughly purged with nitrogen. 200 g of dry silicate was introduced, 1160 mL of mixed heptane and 840 mL of triethylaluminum in heptane (0.60 M) were added and stirred at room temperature. After 1 hour, the mixture was washed with mixed heptane to prepare a silicate slurry of 2,000 mL. Next, 9.6 mL of a heptane solution (0.71 M) of triisobutylaluminum was added to the previously prepared silicate slurry and reacted at 25° C. for 1 hour. In parallel, 2,180 mg (0.3 mM) of (R)-dichloro[1,1′-dimethylsilylenebis{2-methyl-4-(4-chlorophenyl)-4H-azulenyl}]zirconium and 870 mL of heptane were added. , 33.1 mL of a heptane solution (0.71 M) of triisobutylaluminum was added, and the mixture was allowed to react at room temperature for 1 hour. was prepared to

(prepolymerization/washing)
Subsequently, the temperature in the tank was raised to 40° C., and when the temperature was stabilized, propylene was supplied at a rate of 100 g/hour to maintain the temperature. After 4 hours the propylene feed was stopped and maintained for an additional 2 hours.
After the prepolymerization was completed, the residual monomer was purged, stirring was stopped, and after standing for about 10 minutes, 2,400 mL of the supernatant was decanted. Subsequently, 9.5 mL of a heptane solution (0.71 M) of triisobutylaluminum and 5,600 mL of mixed heptane were added, stirred at 40° C. for 30 minutes, allowed to stand for 10 minutes, and then 5,600 mL of the supernatant was removed. Furthermore, this operation was repeated 3 times. When the final supernatant was analyzed for components, the organoaluminum component concentration was 1.23 mM, the Zr concentration was 8.6×10 ⁻⁶ g/L, and the amount present in the supernatant relative to the charged amount was 0.23 mM. 016%. Subsequently, after adding 170 mL of a heptane solution (0.71 M) of triisobutylaluminum, drying was performed under reduced pressure at 45°C. A prepolymerized catalyst containing 2.0 g of polypropylene per g of catalyst was obtained. Using this prepolymerized catalyst, a propylene resin composition was produced according to the following procedure.

(ii) First Polymerization Step A horizontal reactor (L/D=6, internal volume: 100 L) having stirring blades was sufficiently dried, and the inside was sufficiently replaced with nitrogen gas. In the presence of a polypropylene powder bed, while stirring at a rotation speed of 30 rpm, 0.568 g / hour of the prepolymerized catalyst prepared by the above method (as a solid catalyst amount excluding the prepolymerized powder) was added to the upstream part of the reactor. Triisobutylaluminum was fed continuously at 15.0 mmol/hour. The temperature of the reactor is maintained at 65°C and the pressure at 2.1 MPaG, and the monomer mixed gas is continuously reacted so that the ethylene/propylene molar ratio in the gas phase in the reactor is 0.07 and the hydrogen concentration is 100 ppm. Gas phase polymerization was carried out by circulating in the vessel. The polymer powder produced by the reaction was continuously withdrawn from the downstream portion of the reactor so that the amount of powder bed in the reactor was constant. At this time, the amount of polymer withdrawn when the steady state was reached was 10.0 kg/hour.
Analysis of the propylene-ethylene random copolymer obtained in the first polymerization step revealed an MFR of 6.0 g/10 min and an ethylene content of 2.2 wt %.

(iii) Second Polymerization Step The propylene-ethylene copolymer extracted from the first step was continuously supplied to a horizontal reactor (L/D=6, internal volume: 100 L) equipped with stirring blades. While stirring at a rotation speed of 25 rpm, the temperature of the reactor was kept at 70° C. and the pressure was kept at 2.0 MPaG. Gas phase polymerization was performed by continuously circulating the monomer mixed gas in the reactor. The polymer powder produced by the reaction was continuously withdrawn from the downstream portion of the reactor so that the amount of powder bed in the reactor was constant. At this time, oxygen was supplied as an activity inhibitor so that the amount of polymer withdrawn was 17.9 kg/hour, and the amount of polymerization reaction in the second polymerization step was controlled. The activity was 31.429 kg/g-catalyst.
The results of various analyzes of the physical properties of the propylene resin PP (A-1) thus obtained are shown in Table 3 below.

Granulation Furthermore, tetrakis[methylene-3-(3′,5′-di-t-butyl-4′-hydroxyphenyl) is added as antioxidant 1 to 100 parts by weight of the obtained propylene resin PP (A-1). ) Propionate] methane (BASF Japan Co., Ltd. trade name "Irganox 1010") 0.05 parts by weight, antioxidant 2 tris (2,4-di-t-butylphenyl) phosphite (BASF Japan Co., Ltd. Product name "Irgaphos 168") is added, thoroughly stirred and mixed, and extruded with a PCM twin-screw extruder manufactured by Ikegai Seisakusho with a screw diameter of 30 mm at a screw rotation speed of 200 rpm and a discharge rate of 10 kg / hour. Melt kneading is performed at a machine temperature of 200°C, and the molten resin extruded from the strand die is cooled and solidified in a cooling water tank while being taken out. A pellet of (A-1) was obtained.

(2) (H-1) (Propylene homopolymer polymerized with Ziegler catalyst): Novatec PP MA3 (trade name) manufactured by Japan Polypropylene Corporation (Melting peak temperature Tm: 163°C, MFR: 11 g/10 min)
(3) (H-2) Propylene homopolymer polymerized with Ziegler catalyst): Novatec PP FY4 (trade name) manufactured by Japan Polypropylene Corporation (melting peak temperature Tm: 162°C, MFR: 5 g/10 minutes)
(4) (Z-1) (propylene-based block copolymer polymerized with a Ziegler catalyst): trade name Zelas7023 manufactured by Mitsubishi Chemical Corporation (melting peak temperature Tm: 163° C., MFR: 1.5 g/10 minutes)
(5) (R-1) (Propylene-α-olefin random copolymer polymerized with a Ziegler catalyst): Novatec PP EG7C, trade name manufactured by Japan Polypropylene Corporation (Melting peak temperature Tm: 143°C, MFR: 1.7 g /10 minutes)
(6) (W-1) (Propylene-α-olefin random copolymer polymerized with a metallocene catalyst): trade name Wintech WFW4 manufactured by Japan Polypropylene Corporation (melting peak temperature Tm: 135°C, MFR: 7 g/10 minutes )

(II) Ethylene-based polymer (7) (G-1) (ethylene-α-olefin copolymer polymerized with a metallocene catalyst): Trade name Kernel KM340T manufactured by Japan Polyethylene Co., Ltd. (melting peak temperature Tm: 65°C, MFR: 3.5 g/10 minutes, density: 0.880 g/cm ³ )
(8) (G-2) (Ethylene-α-olefin copolymer polymerized with a metallocene catalyst): Trade name Kernel KF360T manufactured by Japan Polyethylene Co., Ltd. (Melting peak temperature Tm: 90°C, MFR: 3.5 g/10 min, density: 0.898 g/cm ³ )
(9) (G-3) (Ethylene-α-olefin copolymer polymerized with a metallocene catalyst): Trade name Kernel KF283 manufactured by Japan Polyethylene Co., Ltd. (Melting peak temperature Tm: 108°C, MFR: 2.5 g/10 min, density: 0.921 g/cm ³ )

(III) Styrene-based elastomer (10) Styrene-based elastomer (S-1): Trade name Kraton G1645 manufactured by Kraton Co., Ltd. (MFR: 2 to 4.5 g/10 minutes, styrene content: 11.5 to 13.5 weight) %)

(Examples 1 to 4) (Comparative Examples 1 to 8)
In the raw material pellets for each layer shown in Table 4 below, the resin composition for the intermediate layer (X), the resin composition for the outer layer (Y), and the resin composition for the inner layer (Z) are blended at the ratio shown in the table. After dry blending, the mixture was melted and kneaded with a twin-screw extruder (KZW-25 manufactured by Technobel Co., Ltd.) to obtain pellets.
A single screw extruder with a diameter of 30 mm was used as the extruder for the intermediate layer, and a single screw extruder with a diameter of 18 mm was used as the extruder for the outer layer and the inner layer. A circular die with a mandrel diameter of 50 mm and a lip width of 1.0 mm Extruded at a set temperature of 200 ° C., water-cooled with a water-cooling ring adjusted to 10 ° C., and water-cooled inflation molding at a speed of 3 m / min so that the folding width was 90 mm. A cylindrical molded body having a total thickness of 200 μm was obtained.
Next, after heat-treating the obtained cylindrical molded body made of the laminated film by the above-described method, it was held in an atmosphere of 23° C. and 50% RH for 24 hours or longer, and then the physical properties of the laminated film were evaluated. . The evaluation results are shown in Table 4 below.

Since Comparative Examples 1 to 8 exceed the specified range of the present invention, the heat resistance, transparency, flexibility, interface strength after sterilization, and performance are insufficient. This is thought to be due to light scattering occurring between different resins with different refractive indices due to the blend of propylene-based resin and ethylene-based resin (ethylene-α-olefin copolymer) for transparency. This study showed that Comparative Example 8 shown in Examples of Japanese Patent Application Laid-Open No. 2011-68116 has low transparency. With regard to heat resistance, it is thought that poor appearance will occur if the density of the first ethylene-α-olefin copolymer is low, and flexibility will be insufficient if component A-1 is not blended. Especially when the range of the present invention is exceeded, it has been shown that the interfacial strength after sterilization is significantly reduced. It became clear that interfacial peeling occurred after sterilization at 121°C.
On the other hand, from Table 4, the polyolefin resin films of Examples 1 to 4, which have formulations and configurations within the specified range of the present invention, have excellent transparency, flexibility, heat resistance, and low-temperature impact resistance. However, it was shown to be a film with excellent interlaminar strength that retains high heat seal strength.

The polyolefin resin film of the present invention is excellent in flexibility, transparency, heat resistance, impact resistance, especially impact resistance at low temperatures (for example, 5°C), and is subjected to high temperature heat treatment such as 121°C. However, the interfacial strength of each layer can be maintained, and the heat treatment package using it is extremely useful for infusion bags and retort packages.

Claims (5)

At least three layers are laminated in the order of the first layer, the second layer and the third layer,
The first layer contains a first ethylene resin composition containing a first ethylene-α-olefin copolymer,
The first ethylene-α-olefin copolymer has a density in the range of 0.915 to 0.935 g/cm ³ and a melt flow rate (190°C, 2.16 kg) in the range of 1 to 10 g/10 minutes. is;
the second layer comprises a second propylene resin composition comprising a second propylene resin and a second ethylene-α-olefin copolymer;
The second propylene resin contains 30 to 70% by weight of a propylene polymer having a melting peak temperature of 120 to 170° C. in DSC measurement, and an α-olefin content of 7 to 30%, based on 100% by weight of the second propylene resin. 70 to 30% by weight of a propylene-α-olefin random copolymer, and a melt flow rate (230°C, 2.16 kg) in the range of 0.5 to 20 g/10 minutes;
The second ethylene-α-olefin copolymer is a metallocene-based ethylene-α-olefin copolymer and has a density in the range of 0.880 to 0.920 g/cm ³ . 10 to 40 wt% of the second ethylene-α-olefin copolymer in wt%;
the third layer comprises a third propylene resin composition comprising a third propylene resin and a styrenic elastomer ;
The third propylene resin has a melting peak temperature in the range of 150 to 170° C. in DSC measurement and a melt flow rate (230° C., 2.16 kg) in the range of 2 to 20 g/10 minutes . 1 to 30% by weight of a styrene-based elastomer in 100% by weight of the resin composition ;
Polyolefin resin film. 2. The polyolefin resin film according to claim 1, wherein the second propylene resin contained in the second propylene resin composition is a metallocene propylene resin. 3. The polyolefin resin film according to claim 2, wherein the first ethylene-α-olefin copolymer contained in the first ethylene resin composition is a metallocene ethylene-α-olefin copolymer. . A package for heat treatment, comprising the polyolefin resin film according to any one of claims 1 to 3 . The package for heat treatment according to claim 4 , which is an infusion bag that can be sterilized at 121°C.