JP5510710B2 - Easy tear polypropylene-based unstretched film and laminate thereof - Google Patents

Description

  The present invention relates to a polypropylene-based unstretched film for high retort and a laminate thereof, having excellent easy tearability in the resin flow direction (MD direction), good impact resistance at low temperatures, and heat sealability. Furthermore, the present invention relates to a polypropylene-based unstretched film and a laminate thereof that have both blocking resistance and can be widely used as a retort packaging bag for high-retort applications (125 to 135 ° C. sterilization).

  Conventionally, sealant films used for retort pouches, medical infusion bags, liquid food pouches, etc. have heat resistance that can handle pressure heat sterilization (retort processing), and impact resistance that can withstand the shock of the distribution process (especially Low temperature impact resistance), sufficient seal strength, blocking resistance, moderate transparency, etc. have been required. The film design for high retort pouches in particular has been designed for the purpose of satisfying other required characteristics in a well-balanced manner, placing the highest importance on heat resistance, low-temperature impact resistance, and seal strength among these required characteristics (patents) References 1, 2). The “retort” described in this report means that heat sterilization exceeds 100 ° C. under pressure. In particular, sterilization at 125 to 135 ° C. is called “high retort”.

  However, when an unstretched film formed by melt extrusion of a resin blended with propylene / ethylene block copolymer or ethylene-based elastomer in propylene / ethylene block copolymer of Patent Documents 1 and 2 is used for a retort pouch, At the time of opening from the notch part (cut provided at the end part), the straight-cut property is poor and the contents are deformed or spilled.

  Therefore, in recent years, a sealant film used for a retort pouch is required to be easily opened from a notch portion without using a blade (easy tearability).

  As a polypropylene film having easy tearability, there is a uniaxially stretched film (Patent Document 3) formed by stretching at a high magnification in the longitudinal direction, but the film of Patent Document 3 is improved in tearing property, but impact resistant. The properties were insufficient for retort use. In addition, for the purpose of increasing the crystallinity of the film and imparting tearability, there are films formed by blending sorbitol derivatives (Patent Document 4) and films formed by blending rosin metal salt compounds (Patent Document 5). , Many odors and extracts after retort treatment are not suitable for high retort applications. In addition, there are films formed by blending crystalline polyethylene resins (Patent Document 6) and films formed by blending polybutene-1 as a crystal nucleating agent (Patent Document 7), both of which are inferior in impact resistance. It was insufficient as a high retort application.

  As described above, the conventional technology has easy tearability in the resin extrusion direction (hereinafter referred to as the flow direction (MD direction)), and has high impact resistance, heat sealability, and blocking resistance. There was no polypropylene-type unstretched film that could be widely used for retort applications (125 to 135 ° C sterilization).

JP 2003-105164 A JP 2000-186159 A JP 7-138423 A Japanese Patent Laid-Open No. 1-299831 JP-A-11-255910 Japanese Patent Laid-Open No. 10-316772 Japanese Patent No. 3813263

  The problem of the present invention is that it has excellent easy tearability in the resin flow direction (MD direction), has good impact resistance at low temperatures, has both heat sealability and blocking resistance, and is used as a retort packaging bag. It is providing the polypropylene-type unstretched film which can be widely used for a high retort use (125-135 degreeC sterilization), and its laminated body.

As a result of various studies, the present inventors have solved the above problem. That is, according to the present invention, the density is 0.865 to 0.890 g / cm ³ and the endothermic amount upon melting (JIS K7122) is 5 to ³⁰ J / with respect to 100 parts by weight of the propylene / ethylene block copolymer (A). a film containing 3 to 10 parts by weight of the low crystalline ethylene elastomer (B) as g, and having a birefringence of 3.0 × 10 ^{−3 to} 5.0 × 10 ^−3. It is a polypropylene-based unstretched film for high retort, more preferably, the falling ball impact strength at a thickness of 60 μm is in the range of 2.0 to 5.0 J / sheet, and phosphoric acid. A polypropylene-based unstretched film for high retort, comprising a metal salt crystal nucleating agent (C) in a range of 0.05 to 0.5 parts by weight, and a single layer or more film is laminated. Other On one side of the wood layers, the polypropylene unstretched film is achieved by a laminate characterized by comprising laminated as a heat seal layer.

  The polypropylene-based unstretched film of the present invention has excellent easy tearability in the resin flow direction (MD direction), has good impact resistance at low temperatures, combines heat sealability and blocking resistance, Usually, it can be used as a sealant film suitable for a retort packaging bag.

  In addition, the polypropylene-based unstretched film of the present invention is laminated as a heat seal layer on another base material, so that when opened, it is excellent in easy tearing, and there is no problem that the contents are deformed or spilled. Retort packaging bags excellent in heat resistance, heat sealability and blocking resistance can be provided.

Next, the polypropylene-type unstretched film according to the present invention and a laminate including the film will be specifically described.
The propylene / ethylene block copolymer (A) (hereinafter sometimes abbreviated as component (A)) used in the present invention polymerizes a polymer part mainly composed of propylene in the gas phase, Next, the second step is a propylene / ethylene block copolymer (A) obtained by polymerizing a copolymer part (A1) of propylene and ethylene having an ethylene content of 20 to 50% by weight in the gas phase, The melt flow rate (hereinafter abbreviated as MFR, unit g / 10 min) at 230 ° C. and a load of 21.18 N is preferably in the range of 1 to 10, and more preferably in the range of 1 to 5. If the MFR is less than 1, the melt viscosity is too high, and it is difficult to stably extrude from the die during film formation. If the MFR exceeds 10, the impact resistance is deteriorated.

  A more preferable range of the ethylene content of the copolymer part (A1) of propylene and ethylene of the propylene / ethylene block copolymer (A) is 30 to 50% by weight. When the ethylene content is less than 20% by weight, the blocking resistance is inferior, which is not preferable.

  The melting point of the propylene / ethylene block copolymer (A) is preferably in the range of 155 ° C to 165 ° C. If the melting point is less than 155 ° C., the heat resistance in the 135 ° C. retort treatment is insufficient, and if it exceeds 165 ° C., the impact resistance deteriorates.

  The low crystalline ethylene elastomer (B) used in the present invention (hereinafter sometimes abbreviated as component (B)) is a low crystalline random copolymer of ethylene and an α-olefin having 3 to 8 carbon atoms. More preferably, it is a low crystalline random copolymer of ethylene and an α-olefin having 3 to 4 carbon atoms. As the low crystalline random copolymer of ethylene and an α-olefin having 3 to 8 carbon atoms, an ethylene / butene random copolymer is preferable because of its high impact resistance, and more preferably ethylene / butene-1 random copolymer. It is a coalescence. The content of the α-olefin having 3 to 8 carbon atoms is in the range of 5 to 25% by weight, and preferably 10 to 20% by weight, since both blocking resistance and impact resistance can be achieved.

The density of the low crystalline ethylene elastomer (B) is 0.865 to 0.890 g / cm ³ , and the endothermic amount of melting in the temperature rising process by a differential scanning calorimeter (DSC) based on JIS K7122 is 5 to 30 J / It must be in the range of g. Density blocking resistance is deteriorated less than 0.865 g / cm ^3, the impact resistance is deteriorated when the density exceeds 0.890 g / cm ^3. Further, when the endothermic amount is less than 5 J / g, the blocking resistance deteriorates, and when it exceeds 30 J / g, the impact resistance deteriorates.

  Moreover, it is preferable that the melt flow rate in 190 degreeC and the load 21.18N is the range of 0.3-5 g / 10min. If the MFR is less than 0.3 g / 10 minutes, the miscibility with other polymers may be reduced, and if it exceeds 5 g / 10 minutes, the blocking resistance of the film may be deteriorated. In addition, a manufacturing method in particular is not restrict | limited, It can manufacture using a well-known method.

  The polypropylene-based unstretched film of the present invention is a film containing 3 to 10 parts by weight of the low crystalline ethylene-based elastomer (B) with respect to 100 parts by weight of the propylene / ethylene block copolymer (A). is necessary. When the usage-amount of each said component is less than the said range, it exists in the tendency for the performance of the film obtained to fall. That is, when the amount of the low crystalline ethylene elastomer (B) exceeds 10 parts by weight with respect to 100 parts by weight of the propylene / ethylene block copolymer (A), the blocking resistance and easy tear resistance are poor. When the amount of the low crystalline ethylene elastomer (B) is less than 3 parts by weight with respect to 100 parts by weight of the ethylene block copolymer (A), the impact resistance becomes insufficient.

The polypropylene-based unstretched film of the present invention needs to have a birefringence of 3.0 × 10 ^{−3 to} 5.0 × 10 ⁻³ . Further, more preferred range is ^{4.0 × 10 -3 ~5.0 × 10 -3} . When the birefringence is less than 3.0 × 10 ⁻³ , the tear strength is increased, and when it exceeds 5.0 × 10 ⁻³ , the tear strength is decreased but the impact resistance is insufficient.

  As a method for controlling the birefringence in the present invention, for example, the above mixed resin is melted at a low temperature of 180 ° C. to 250 ° C., preferably 200 ° C. to 230 ° C., and extruded from a die set with a slit gap of 1 mm or more. Further, a method of cooling on a casting drum maintained at a high temperature of 50 to 90 ° C., preferably 70 to 90 ° C., and winding at a speed of 10 to 100 m / min can be mentioned.

Another method is to increase the crystallinity of the film by adding a crystal nucleating agent. As the crystal nucleating agent, a known metal nucleating agent for polypropylene, such as a metal phosphate nucleating agent, a sorbitol nucleating agent, a carboxylic acid metal salt nucleating agent, and a high density polyethylene having a density of 0.935 g / cm ³ or more. Although it can be used, it is sometimes abbreviated as a metal phosphate-based crystal nucleating agent (C) (hereinafter referred to as component (C)) that has little odor generation and is solvent-resistant during retort processing. ) Can be suitably used. Sorbitol-based nucleating agents and carboxylic acid metal salt-based nucleating agents are inferior in odor and solvent resistance, and high-density polyethylene with a density of 0.935 g / cm ³ or more has a weak effect as a nucleating agent and has sufficient tearability. It may be difficult to obtain.

  In the present invention, when the metal phosphate crystal nucleating agent (C) is used, 0.05 to 0.5 parts by weight of the metal phosphate crystal based on 100 parts by weight of the component (A). The inclusion of the nucleating agent (C) is preferable because the effect as a crystal nucleating agent can be expected.

  Moreover, it is preferable that the falling ball impact strength at a thickness of 60 μm is 2.0 to 5.0 J / sheet. A more preferable range is 2.0 to 3.5 J / sheet. Those having a falling ball impact strength of less than 2.0 J / sheet at a film thickness of 60 μm are likely to have insufficient impact resistance, and those having a film thickness of more than 5.0 J / sheet are liable to have poor tearability. In the present invention, as a method for controlling the falling ball impact strength, for example, there is a method of adjusting the addition amount of the low crystalline ethylene elastomer (B). The falling ball impact strength can be adjusted proportionally by the addition amount of the low crystalline ethylene elastomer (B). However, when the amount added is outside the range of the present invention, the performance of the obtained film tends to be lowered. That is, when the amount of the low crystalline ethylene elastomer (B) exceeds 10 parts by weight with respect to 100 parts by weight of the propylene / ethylene block copolymer (A), the falling ball impact strength is too high and the blocking resistance and the easy tearing property. On the other hand, when the low crystalline ethylene elastomer (B) is less than 3 parts by weight relative to 100 parts by weight of the propylene / ethylene block copolymer (A), the falling ball impact strength is too small and the impact resistance is low. It becomes insufficient.

  The polypropylene-based unstretched film of the present invention can be used as a film for general packaging even as a single film, and can be suitably used particularly for retort food packaging requiring impact resistance.

  Next, the polypropylene-based unstretched film of the present invention can be produced by a known film-forming method such as a T-die method or a tubular method, and in particular, a method for forming an unstretched film by the T-die method. However, it is preferable because it is easy to control the birefringence and crystallinity of the film. Although the film-forming method of the film of the present invention by the T-die method will be described below, it is not limited to this method.

  The above-mentioned pellets or powder mixture of component (A) and component (B) are melt-kneaded using a uniaxial or biaxial melt extruder, filtered through a filter, and extruded from a T die die to obtain a film. . In the case of using the component (C), pellets prepared by making the powdered metal phosphate-based crystal nucleating agent (C) into a master batch using a polypropylene resin as a carrier resin by a known method, the component (A) and (B) What is necessary is just to melt-knead with the pellet of a component. At this time, the temperature of the molten polymer extruded from the melt extruder can usually be 180 to 300 ° C., but 200 to 270 ° C. is preferable in order to prevent the decomposition of the polymer and obtain a film of good quality. In order to obtain the desired tear strength, it is more preferable to extrude at a low temperature of 200 ° C to 230 ° C. When extruding from a T-die, the extruded film is usually brought into contact with a cooling roll set at a constant temperature of 20 to 50 ° C., cooled and solidified, and then wound, but in order to obtain the desired tear strength, cooling is performed. It is desirable to increase the crystallinity of the film by setting the roll temperature to a high temperature of 50 to 90 ° C, more preferably 70 to 90 ° C. Although the film of the present invention can be stretched after cooling and solidification, it is not preferable because the easy tearability is improved and the impact resistance is remarkably lowered. The thickness of the film of the present invention is preferably 20 to 300 μm, more preferably 40 to 100 μm.

  The polypropylene-based unstretched film of the present invention can contain an antioxidant, a heat stabilizer, an antistatic agent, an acidic substance absorbent, an antiblocking agent, a lubricant and the like as long as the object of the present invention is not impaired.

  Further, the polypropylene-based unstretched film of the present invention is subjected to surface treatment such as corona discharge treatment, corona discharge treatment in a nitrogen or carbon dioxide atmosphere, plasma treatment, ozone treatment or the like, which is usually performed industrially as necessary. You can also

  When the laminate according to the present invention is used as a retort packaging material, the above-mentioned polypropylene-based unstretched film (hereinafter referred to as a single layer or two or more layers of transparent film and other base material layer made of aluminum foil (AL foil)) It can be set as the structure which laminated | stacked this film and description. For example, as a laminate composed of a base layer of a single layer film, a stretched polyethylene terephthalate film (hereinafter abbreviated as PET) / this film, a stretched nylon film (hereinafter abbreviated as ON) / this film, silica-deposited PET / this film, Alumina-deposited PET / main film, silica / alumina binary-deposited PET / main film, silica-deposited ON / main film, alumina-deposited ON / main film, barrier PET / main film coated with acrylic resin, etc. As a laminate comprising the above transparent film base layer, PET / ON / main film, silica-deposited PET / ON / main film, alumina-deposited PET / ON / main film, barrier PET coated with acrylic resin / ON / this film, PET / EVOH (ethylene vinyl alcohol Polymer film) / main film, PET / transparent deposition ON / main film, etc., and a laminate composed of a substrate layer in which a single layer or more transparent film and AL foil are bonded together is PET / ON / Al foil / main. A film, PET / Al foil / ON / main film or PET / Al foil / main film can be preferably used.

  As the method for producing the laminate, an ordinary dry laminating method in which the constituent films of the laminate are bonded using an adhesive can be suitably employed. However, if necessary, the polypropylene-based unstretched film and other base material layers of the present invention can be used. For laminating, a method of directly extruding and laminating a polyethylene resin or polypropylene resin can also be employed. These laminates are used after being made into bags in a flat bag, a standing pouch, etc., using the polypropylene-based unstretched film as a seal layer (inner surface of the bag).

  In addition, the laminated structure of these laminates has the required characteristics of packaging bags (for example, barrier performance to satisfy the quality retention period of the food to be packaged, size / impact resistance that can cope with the weight of the contents, visibility of the contents) Etc.).

The present invention will be described based on examples, but the present invention is not limited thereto.
The characteristic measurement method and the effect evaluation method in the present invention are as follows.

(1) Falling ball impact strength A film sample (12 cm × 12 cm) was placed in an autoclave (SR-240 manufactured by Tommy Seiko Co., Ltd.) and subjected to pressure heat sterilization (high retort) treatment at 135 ° C. for 30 minutes. The film sample is fixed to a metal frame and kept at 0 ° C., and a drop of 0.5351 kg of iron balls is dropped from a height of 2 m, and the drop speed when the sample is broken through and only the iron balls when there is no sample The impact energy (low temperature impact resistance) is obtained from the following formula from the speed difference with the drop speed of

E = (1/2) · M · L ² (1 / t ₀ ² -1 / t ₁ ² )
E: Low temperature impact resistance [J]
M: Mass of iron ball [0.5351 kg]
L: Distance between two phototubes [0.1 m]
t ₀ : Iron ball passage time when there is no film [s]
t ₁ : Iron ball passing time when breaking through the film [s]
In addition, unless special low temperature impact resistance is requested | required, if E is 2.0J or more, it can be used without a problem in retort packaging use.

(2) Tear strength: In accordance with JIS K7128-1 (trouser tear method), in a constant temperature room of 23 ° C., a test piece having a width of 50 mm (TD) and a length of 150 mm (MD) is cut into a center of a strip of 75 mm. The tearing force (N) in the MD direction was measured at a speed of 200 mm / min. It was judged that 1.2N or less has easy tearability.
(Note) MD: Flow direction of resin, TD: Direction perpendicular to the flow direction of resin.

(3) Birefringence (Δn): Measured by a normal compensator method using a POH polarization microscope manufactured by Nippon Optics Co., Ltd. as a light source with white light. A (MD) 50 mm × (TD) 30 mm film sample is prepared and set on the stage of a deflection microscope. Insert the analyzer, set the scale of the compensator to 30, and make it a dark field. Rotate the stage 45 degrees to the right or left. Rotate the compensator toward the number larger than 30 and the scale of the compensator when the appearing shadow is centered is (a), rotate the compensator toward the number smaller than 30 and the appearing shadow is located in the center The time scale of the compensator is measured as (b), and each is measured (read to 1/10 of the minimum scale). Further, the compensator is returned to 30, the analyzer is removed, the thickness d of the sample is measured, and the birefringence (Δn) is calculated based on the following formula (however, the arithmetic average value of 20 measurements is taken as the measurement value).
Δn = T / d (T = nλ ₀ + ε)
λ ₀ = 589.3 mμ (provided from C / 1000 and i in the description of the rights compensator and i; i; (ab) (difference in compensator reading)).

(4) Blocking resistance A film sample having a width of 30 mm and a length of 100 mm is prepared, and a load of 5 N / 12 cm ² is applied to the surface where the ranges of 30 mm × 40 mm are overlapped with each other in an oven at 60 ° C. After heat treatment for 24 hours, the plate was allowed to stand for 30 minutes or more in an atmosphere of 23 ° C. and humidity 65% RH, and then the shear peel strength was measured at a tensile speed of 300 mm / min using Tensilon manufactured by Orientec Corporation. In this measurement method, a shear peeling force of 15 N / 12 cm ² or less was judged good.

(5) Heat sealability (after high retort treatment)
The same surfaces are overlapped, and a heat-sealed sample is sealed in a pouch filled with water with a flat plate heat sealer (both sides heating) at a sealing temperature of 180 ° C., a sealing pressure of 20 N / cm ² , and a sealing time of 1 second. . It is put into an autoclave (SR-240 manufactured by Tommy Seiko Co., Ltd.), subjected to pressure heat sterilization (high retort) treatment at 135 ° C for 30 minutes, sampled to a width of 15 mm, and 180 ° centered on the heat seal part And the heat seal strength was measured at a tensile speed of 300 mm / min using Tensilon manufactured by Orientec. If the seal strength is 45 N / 15 mm or more in this measurement method, it can be used favorably for normal retort applications.

(6) Odor sensory test A sample of 20 cm × 25 cm × 6 sheets (about 20 g) is taken and cut into strips having a width of 5 to 10 mm. Seal in a 250 cc wide-mouth glass bottle. This is put into an oven at 60 ° C., taken out after 30 minutes, judged by five panelists, and each judgment value and their average value are calculated to the first decimal place. It can be satisfactorily used for ordinary retort applications with a judgment value of 2 or less.
Judgment criteria Criteria Degree of odor 4 Very strong or stimulating odor 3 Strong odor 2 Feel weak odor 1 Almost no odor.

(7) Endothermic amount during melting (Crystal melting heat amount ΔHm)
Using a DSC (Automatic Differential Scanning Calorimeter) DSC-60A type manufactured by Shimadzu Corporation, a crystal sample from a thermogram when 3 mg of a chip sample was heated at a heating rate of 10 ° C./min based on JIS-K7122 The amount of heat of fusion ΔHm was determined, and the endothermic amount was calculated (J / g).

[Example 1]
(A) A propylene homopolymer part is polymerized in the gas phase in the first step using a Ziegler-Natta type catalyst as the component (A), and then in the gas phase, propylene and ethylene having an ethylene content of 35% by weight in the gas phase 100 parts by weight of a propylene / ethylene block copolymer (melting point: 163 ° C., MFR: 2.5 g / 10 min) obtained by polymerizing the copolymer part of (B) with a density of 0.885 g / cm ³ An ethylene butene-1 random copolymer having a MFR of 3.6 g / 10 min at 190 ° C. under a load of 21.18 N and an endothermic amount (JIS K7122) at melting of 24 J / g (Tafma manufactured by Mitsui Chemicals, Inc.) -A4085) 10 parts by weight in a pellet state are mixed with a blender, supplied to a single screw extruder, melt kneaded and mixed at 220 ° C., filtered through a filter, extruded through a T die, and a surface temperature of 8 After cooled and solidified wound on metal drums ° C., one side with corona discharge treatment wound up at 60 m / min to obtain an undrawn film having a thickness of 60 [mu] m. As shown in Table 1, the obtained film has a tear strength of 1.2 N, a birefringence of 3.0 × 10 ⁻³ , a falling ball impact strength of 5.0 J / sheet, easy tearability, and low temperature impact resistance. It was good and excellent in heat seal strength, blocking resistance and odor.

[Examples 2-3]
A film having a thickness of 60 μm was obtained in the same manner as in Example 1 except that the mixing ratio of the components (A) and (B) used in Example 1 was changed as shown in Table 1. The quality evaluation results of these films are as shown in Table 1. They were excellent in easy tearability and low-temperature impact properties, and excellent in heat seal strength, blocking resistance and odor.

[Examples 4 to 6]
In addition to the components (A) and (B) used in Example 1, a masterbatch containing 6% by weight of a phosphate ester metal crystal nucleating agent as component (C) (Tokyo Ink PPM ST-0024, carrier) Resin: Homopolypropylene, MFR: 7 g / 10 min) was used, and a film having a thickness of 60 μm was obtained in the same manner as in Example 1 except that the mixing ratio was changed as shown in Table 1. The quality evaluation results of these films are as shown in Table 1. They were excellent in easy tearability and low-temperature impact properties, and excellent in heat seal strength, blocking resistance and odor.

[Example 7]
As component (A) and component (B) used in Example 1, the density was 0.869 g / cm ³ , 190 ° C., the MFR at a load of 21.18 N was 3.0 g / 10 min, and the endotherm during melting (JIS K7122). ) Was 10 J / g ethylene / propylene random copolymer (Tafma-P0280 manufactured by Mitsui Chemicals, Inc.), and the mixing ratio was changed as shown in Table 1, exactly as in Example 3, A film having a thickness of 60 μm was obtained. The quality evaluation results of the obtained film are as shown in Table 1. The film was excellent in easy tearability and low-temperature impact properties, and excellent in heat seal strength, blocking resistance and odor.

[Example 8]
The polymer used in Example 3 was mixed with a blender in a pellet state and supplied to a single screw extruder, melted and kneaded at 220 ° C., filtered through a filter, extruded from a T-die, and a metal having a surface temperature of 90 ° C. After being wound around a drum and cooled and solidified, one side was subjected to corona discharge treatment and wound at a speed of 60 m / min to obtain an unstretched film having a thickness of 60 μm. The quality evaluation results of the obtained film are as shown in Table 1. The film was excellent in easy tearability and low-temperature impact properties, and excellent in heat seal strength, blocking resistance and odor.

[Example 9]
The polymer used in Example 3 was mixed with a blender in a pellet state and supplied to a single screw extruder, melted and kneaded at 220 ° C., filtered through a filter, extruded from a T die, and a metal having a surface temperature of 50 ° C. After being wound around a drum and cooled and solidified, one side was subjected to corona discharge treatment and wound at a speed of 60 m / min to obtain an unstretched film having a thickness of 60 μm. The quality evaluation results of the obtained film are as shown in Table 1. The film was excellent in easy tearability and low-temperature impact properties, and excellent in heat seal strength, blocking resistance and odor.

[Example 10]
The polymer used in Example 3 was mixed with a blender in a pellet state and supplied to a single screw extruder, melted and kneaded at 200 ° C., filtered through a filter, extruded from a T die, and a metal having a surface temperature of 80 ° C. After being wound around a drum and cooled and solidified, one side was subjected to corona discharge treatment and wound at a speed of 60 m / min to obtain an unstretched film having a thickness of 60 μm. The quality evaluation results of the obtained film are as shown in Table 1. The film was excellent in easy tearability and low-temperature impact properties, and excellent in heat seal strength, blocking resistance and odor.

[Example 11]
The polymer used in Example 3 was mixed in a blender in a pellet state and supplied to a single screw extruder, melted and kneaded at 230 ° C., filtered through a filter, extruded from a T die, and a metal having a surface temperature of 80 ° C. After being wound around a drum and cooled and solidified, one side was subjected to corona discharge treatment and wound at a speed of 60 m / min to obtain an unstretched film having a thickness of 60 μm. The quality evaluation results of the obtained film are as shown in Table 1. The film was excellent in easy tearability and low-temperature impact properties, and excellent in heat seal strength, blocking resistance and odor.

[Comparative Example 1]
Using only the component (A) used in Example 1, an unstretched film having a thickness of 60 μm was obtained in exactly the same manner as in Example 1. The quality evaluation result of the obtained film is as shown in Table 1, and since it does not contain a predetermined amount of the low crystalline ethylene elastomer of component (B), it is easy to tear, heat seal strength, blocking resistance, odor Although there was no problem, the low-temperature impact property was poor and it was not suitable for retort packaging.

[Comparative Example 2]
An unstretched film having a thickness of 60 μm was obtained in the same manner as in Example 1 except that the mixing ratio of the polymer (A) component and the component (B) used in Example 1 was changed as shown in Table 1. The quality evaluation results of the obtained film are as shown in Table 1, and since there is little content of the component (B), easy tearing, heat seal strength, blocking resistance, and odor are not a problem, but low temperature impact resistance It was defective and unsuitable for retort packaging.

[Comparative Example 3]
An unstretched film having a thickness of 60 μm was obtained in the same manner as in Example 1 except that the mixing ratio of the components (A) and (B) used in Example 1 was changed as shown in Table 1. The quality evaluation results of the obtained film are as shown in Table 1, and since there is a large amount of the component (B), there are no problems with low temperature impact and odor, but easy tearing, heat seal strength, and blocking resistance. It was defective and unsuitable for retort packaging.

[Comparative Example 4]
The polymer used in Example 3 was mixed in a blender in a pellet state and supplied to a single screw extruder, melted and kneaded at 220 ° C., filtered through a filter, extruded through a T die, and the surface temperature of the metal drum was set to 80. An unstretched film having a thickness of 60 μm was obtained in exactly the same manner as in Example 1 except that the temperature was changed from 40 ° C. to 40 ° C., and cooling and solidification were performed. The quality evaluation results of the obtained film are as shown in Table 1. Although there are no problems with low temperature impact, heat seal strength, blocking resistance and odor, the birefringence is low and the tear strength is high. I didn't have it.

[Comparative Example 5]
As component (A) and component (B) used in Example 1, MFR at a density of 0.859 g / cm ³ , 190 ° C. and a load of 21.18 N was 1.8 g / 10 minutes, and an endothermic amount upon melting (JIS K7122). ) Was 3J / g ethylene / propylene random copolymer (Tafma-P0375 manufactured by Mitsui Chemicals, Inc.), and the mixing ratio was changed as shown in Table 1, exactly as in Example 1, A film having a thickness of 60 μm was obtained. The quality evaluation results of the obtained film are as shown in Table 1. Although there are no problems with low-temperature impact resistance, blocking resistance, heat sealability, and odor, the birefringence is low and the tear strength is high. It did not have sex.

[Comparative Example 6]
As component (A) and component (B) used in Example 1, the density was 0.893 g / cm ³ , 190 ° C., MFR at a load of 21.18 N was 3.6 g / 10 min, and the endotherm during melting (JIS K7122). ) Was 37 J / g ethylene butene-1 random copolymer (Tafma-A4090 manufactured by Mitsui Chemicals, Inc.), and the mixing ratio was changed as shown in Table 1. Thus, a film having a thickness of 60 μm was obtained. The quality evaluation results of the obtained film are as shown in Table 1 and are excellent in easy tearing, blocking resistance, heat sealability, and odor, but have poor low-temperature impact properties and are not suitable for retort packaging applications. It was.

Claims (4)

Low crystal having a density of 0.865 to 0.890 g / cm ³ and an endothermic amount upon melting (JIS K7122) of 5 to 30 J / g with respect to 100 parts by weight of the propylene / ethylene block copolymer (A). A film containing 3 to 10 parts by weight of a conductive ethylene-based elastomer (B), wherein the birefringence is in the range of 3.0 × 10 ^{−3 to} 5.0 × 10 ^−3. Polypropylene unstretched film for high retort. The polypropylene-based unstretched film according to claim 1, wherein a falling ball impact strength at a film thickness of 60 μm determined by the following formula is 2.0 to 5.0 J / sheet.
[How to determine falling ball impact strength]
A film sample (12 cm x 12 cm) subjected to high retort treatment (135 ° C x 30 min) is fixed to a metal frame and held at 0 ° C, and a 0.5351 kg iron ball is dropped from a height of 2 m The impact energy (low temperature impact resistance) is obtained from the following formula from the difference between the drop speed when breaking through and the drop speed of only the iron ball when there is no sample.
E = (1/2) · M · L ² (1 / t ₀ ² -1 / t ₁ ² )
E: Low temperature impact resistance [J]
M: Mass of iron ball [0.5351 kg]
L: Distance between two phototubes [0.1 m]
t ₀ : Iron ball passage time when there is no film [s]
t ₁ : Iron ball passing time when breaking through the film [s] 3. The polypropylene-based unstretched film according to claim 1, wherein the phosphoric acid metal salt-based crystal nucleating agent (C) is contained in an amount of 0.05 to 0.5 parts by weight. The laminated body by which the polypropylene-type unstretched film in any one of Claims 1-3 is laminated | stacked on one side of the other base material layer on which the film of the single layer or more was laminated | stacked as a heat seal layer.