JP2011011334A - Multilayered film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polypropylene film which is excellent in the balance of transparency, slip properties and low temperature impact resistance.SOLUTION: The multilayered film is constituted by laminating a b-layer, which comprises a polypropylene resin other than a polypropylene copolymer at least, on one side of an a-layer comprising the polypropylene copolymer, which contains 50-95 wt.% of a polymer component (component A) based on a structural unit originating from propylene and 5-50 wt.% a polymer component (component B) of propylene, ethylene and a ≥4C α-olefin characterized in that the content (X) of the structural unit originating from propylene is 10≤X<50 wt.%, the content (Y) of a structural unit originating from ethylene is 50<Y≤70 wt.% and the content (Z) of a structural unit originating from the ≥4C α-olefin is 0<Z≤20 wt.%, and characterized in that the thickness ratio (a-layer/b-layer) of the a-layer and the b-layer is larger than 1.

Description

The present invention relates to a multilayer film. More specifically, the present invention relates to a multilayer film suitable as a food packaging film having an excellent balance of slipperiness, blocking resistance, and impact resistance at low temperatures.

Polypropylene is widely used in the field of packaging materials such as food packaging and fiber packaging because it is excellent in rigidity, heat resistance and packaging suitability.

Japanese Patent Application Laid-Open No. 51-89579 discloses a food packaging formed of a laminated sheet having at least two layers, an inner layer of an ethylene-propylene copolymer resin film having a specific property and an outer layer of a heat resistant resin film. It is described that the bag is excellent in transferability and heat resistance of the heat seal part when subjected to high temperature and short time heat sterilization treatment, and also excellent in impact resistance and strength of the heat seal part.

JP-A-62-3951 discloses a layer composed of an ethylene-propylene block copolymer or a blend of an ethylene-propylene block copolymer and an olefin copolymer, and a polypropylene or ethylene-propylene random copolymer. It is described that a laminated film composed of a layer is excellent in transparency, gloss, impact resistance and the like.

Japanese Patent Application Laid-Open No. 2002-210896 comprises a polypropylene resin composition containing a polypropylene copolymer having specific properties and having a heat of crystal melting measured by a differential scanning calorimeter (DSC) of 80 J / g or less. A food packaging film formed by laminating a layer made of a polypropylene resin composition containing a polypropylene copolymer having a 20 ° C. xylene-soluble component amount of less than 15% by weight on at least one side of the layer to a thickness of 10 μm or less. It is described that it is excellent in blocking resistance, bag drop strength and food hygiene.

JP 51-89579 A

Japanese Patent Laid-Open No. 62-3951

JP 2002-210896 A

However, the above laminate may not be particularly satisfactory in terms of impact resistance at low temperatures, and is not satisfactory in terms of the balance of slipperiness, blocking resistance and impact resistance at low temperatures.
An object of the present invention is to provide a multilayer film having an excellent balance of slipperiness, blocking resistance, and impact resistance at low temperatures.

As a result of intensive studies, the present inventors have found that the present invention can solve the above problems, and have completed the present invention.

That is, the present invention has a polymer component (component A) of 50 to 95% by weight whose main component is a structural unit derived from propylene, and the content (X) of the structural unit derived from propylene is 10 ≦ X <50 weight. %, The content of structural units derived from ethylene (Y) is 50 <Y ≦ 70 wt%, and the content of structural units derived from α-olefins having 4 or more carbon atoms (Z) is 0 <Z ≦ 20% by weight (provided that the total of X, Y and Z is 100% by weight), and a structure derived from an α-olefin having 4 or more carbon atoms with respect to the content (X) of a structural unit derived from propylene Polypropylene copolymer containing 5 to 50% by weight of a polymer component (component B) of propylene, ethylene and an α-olefin having 4 or more carbon atoms, having a unit content (Z) weight ratio of 1 or less. A layer comprising at least The surface, will be b layer of polypropylene-based resin other than the polypropylene copolymer is laminated to a multilayer film, wherein the thickness ratio (a layer / b layer) is greater than 1.

According to the multilayer film of the present invention, it is possible to obtain a multilayer film having an excellent balance of slipperiness, blocking resistance, and impact resistance at low temperatures.

The multilayer film of the present invention comprises a polymer component (component A) whose main component is a structural unit derived from propylene, and a polymer component (component B) of propylene, ethylene and an α-olefin having 4 or more carbon atoms. It is a multilayer film formed by laminating a b layer made of a polypropylene resin on at least one side of an a layer containing a polypropylene copolymer.

Here, the proportion of component A and component B in the polypropylene copolymer is in the range of 50 to 95% by weight of component A and 5 to 50% by weight of component B, preferably 60 to 95% by weight of component A. %, Component B is 5 to 40% by weight, more preferably component A is 60 to 90% by weight, and component B is 10 to 40% by weight. When component B is less than 5% by weight, impact resistance at low temperatures is inferior, and when component B exceeds 50% by weight, slipping property and blocking resistance may be deteriorated.

Component A is a polymer whose main component is a structural unit derived from propylene. From the viewpoint of rigidity, the melting point preferably exceeds 155 ° C, more preferably 160 ° C or higher. Component A may be copolymerized with an α-olefin such as ethylene or 1-butene within a range where the melting point does not become 155 ° C. or lower, but is preferably a propylene homopolymer. When an α-olefin such as ethylene or 1-butene is copolymerized, the content of the structural unit derived from the α-olefin in the polymer component (component A) whose main component is the structural unit derived from propylene is 5% by weight or less, preferably 3% by weight or less (the polymer component mainly composed of propylene is 100% by weight). Although there is no restriction | limiting in particular about the intrinsic viscosity of the component A, the range of 1.5-3.0 dL / g is preferable, and the range of 1.5-2.5 dL / g is further more preferable.

The content (Y) of the structural unit derived from ethylene contained in Component B is 50 <Y ≦ 70 wt%, preferably 52 ≦ Y ≦ 70 wt% (however, derived from propylene contained in Component B) The total of the content of structural units (X), the content of structural units derived from ethylene (Y), and the content of structural units derived from α-olefins having 4 or more carbon atoms (Z) is 100% by weight. ). When the content of the structural unit derived from ethylene is 50% by weight or less, or exceeds 70% by weight, impact resistance at low temperatures may be lowered.

The content (Z) of the structural unit derived from the α-olefin contained in Component B is 0 <Z ≦ 20 wt%, preferably 1 ≦ Z ≦ 16 wt% (provided that propylene contained in Component B The total of the content of structural units derived from (X), the content of structural units derived from ethylene (Y), and the content of structural units derived from α-olefins having 4 or more carbon atoms (Z) is 100 weights. %). When the content of the structural unit derived from α-olefin exceeds 0% by weight or 20% by weight, the impact resistance at low temperature may be lowered.

Examples of the α-olefin having 4 or more carbon atoms contained in Component B include 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 4-methyl-1-pentene, vinylcyclohexane, vinylnorbornane. 1-butene is preferable. Although there is no restriction | limiting in particular about the intrinsic viscosity of the component B, the range of 2.0-5.0 dL / g is preferable from a viewpoint of fish-eye generation | occurrence | production, and the range of 2.5-4.5 dL / g is further more preferable.

As a method for producing a polypropylene-based copolymer used in the multilayer film of the present invention, after polymerizing a polymer component (component A) whose main component is a structural unit derived from propylene, propylene, ethylene, and carbon number are continuously produced. Examples include a method of polymerizing a polymer component (component B) with 4 or more α-olefins, and can be produced by various polymerization methods using a normal stereoregular catalyst.

Examples of the stereoregular catalyst include a catalyst comprising a solid titanium catalyst component, an organometallic compound catalyst component, and an electron donor used as necessary, and a transition of group IVB of the periodic table having a cyclopentadienyl ring. Examples include a catalyst system composed of a metal compound and an alkylaluminoxane, or a compound composed of a group IVB transition metal compound having a cyclopentadienyl ring and a compound which reacts with it to form an ionic complex and an organoaluminum compound. .

Examples of the solid titanium catalyst component include a solid catalyst component precursor obtained by reducing a titanium compound with an organic magnesium compound in the presence of a silicon compound, a halogenated compound (for example, titanium tetrachloride), and an electron donor ( For example, a trivalent titanium compound-containing solid catalyst component obtained by contact treatment of an ether compound or a mixture of an ether compound and an ester compound) may be mentioned.

Examples of the organometallic compound catalyst component include an organoaluminum compound having at least one Al-carbon bond in the molecule, and a trialkylaluminum, a mixture of a trialkylaluminum and a dialkylaluminum halide, or an alkylalumoxane is preferable. In particular, triethylaluminum, triisobutylaluminum, a mixture of triethylaluminum and diethylaluminum chloride, or tetraethyldialumoxane is preferable.

Examples of the electron donor include oxygen-containing compounds, nitrogen-containing compounds, phosphorus-containing compounds, and sulfur-containing compounds, among which oxygen-containing compounds or nitrogen-containing compounds are preferable, oxygen-containing compounds are more preferable, and alkoxysilicones or Ethers are particularly preferred.

Specifically, for example,
(A) In the coexistence of a silicon compound having a Si—O bond, the general formula Ti (OR ₁ ) _n X _4-n (R ₁ is a hydrocarbon group having 1 to 20 carbon atoms, X is a halogen electron, and n is 0 <Representing a number of n ≦ 4.) The solid product obtained by reducing the titanium compound represented by the organic magnesium compound is treated with a mixture of an ester compound, an ether compound and titanium tetrachloride. -Valent titanium compound-containing solid catalyst component,
(B) Organoaluminum compound (c) A catalyst system comprising a silicon compound having a Si—OR ₂ bond (R ₂ is a hydrocarbon group having 1 to 20 carbon atoms) can be mentioned.

Further, the molar ratio of Al atom in component (b) / Ti atom in component (a) is 1 to 2000, preferably 5 to 1500, and the molar ratio of Al atom in component (c) / component (b) is It is used so that it may become 0.02-500, preferably 0.05-50.

The polymerization method will be described below. The polymerization format may be either batch type or continuous type. Further, slurry polymerization or solution polymerization using an inert hydrocarbon solvent such as propane, butane, isobutane, pentane, hexane, heptane, and octane, and bulk polymerization or gas phase polymerization using a liquid olefin as a medium at the polymerization temperature are also possible. Although superposition | polymerization temperature can be implemented over -30-300 degreeC normally, 20-180 degreeC is preferable. Although there is no restriction | limiting in particular regarding the polymerization pressure, Generally the pressure of a normal pressure-10MPa, Preferably about 200kPa-5MPa is employ | adopted by the point that it is industrial and economical. In particular, the second step described later is preferably gas phase polymerization.
During polymerization, a chain transfer agent such as hydrogen can be added to adjust the molecular weight of the polymer.

Examples of the polypropylene copolymer used in the multilayer film of the present invention include a method of producing by the following steps.
Polymerization step 1: Propylene is homopolymerized to produce a polypropylene homopolymer component (component A), or propylene and an olefin selected from the group consisting of ethylene and an α-olefin having 4 to 10 carbon atoms. A step of copolymerization to produce a polymer component (component A) whose main component is a structural unit derived from propylene. Polymerization step 2: Mainly the structural unit derived from the polypropylene homopolymer component or propylene obtained in step 1 above. In the presence of a copolymer component as a component, propylene, ethylene and an α-olefin having 4 or more carbon atoms are copolymerized to form a polymer component (component) of propylene, ethylene and an α-olefin having 4 or more carbon atoms. B) generating step

A time for polymerizing a polymer component (component A) whose main component is a structural unit derived from propylene, and a time for polymerizing a polymer component (component B) of propylene, ethylene and an α-olefin having 4 or more carbon atoms; , The ratio of component A and component B can be changed.
In addition, by polymerizing a polymer component (component B) of propylene, ethylene and an α-olefin having 4 or more carbon atoms, by changing the gas composition in the mixed gas of propylene, ethylene and α-olefin, the component The composition of B can be changed.

The polypropylene resin used for the b layer of the multilayer film of the present invention is a polypropylene resin other than the polypropylene copolymer. Specific examples include a propylene homopolymer, a propylene-ethylene copolymer, a propylene-butene copolymer, a propylene-ethylene-butene copolymer, and a propylene-ethylene block copolymer. By using a propylene homopolymer for the b layer, a multilayer film having excellent rigidity in addition to the effects of the present invention can be obtained. By using other copolymers for the b layer, in addition to the effects of the present invention, heat sealability can be obtained. An excellent multilayer film is obtained.

From the viewpoint of impact resistance at low temperature, the multilayer film of the present invention has a thickness ratio (a layer / b layer) of more than 1, preferably a layer / b layer ≧ 1.5, more preferably a layer. / B layer ≧ 2. The thickness of the multilayer film of the present invention is not particularly limited, but is usually 10 to 500 μm, preferably 10 to 100 μm.
The layer structure of the multilayer film of the present invention is a structure in which the b layer is laminated on at least one surface of the a layer, but may be a structure in which both surfaces of the a layer are laminated with the b layer.

The method for producing the multilayer film of the present invention is not particularly limited, and a known method for producing a laminated film can be mentioned. For example,
(1) A polypropylene-based copolymer comprising a polymer component (component A) whose main component is a structural unit derived from propylene, and a polymer component (component B) of propylene, ethylene and an α-olefin having 4 or more carbon atoms. Method of laminating polymer and polypropylene resin by coextrusion (2) Polymer component (component A) whose main component is a structural unit derived from propylene, propylene, ethylene, and α-olefin having 4 or more carbon atoms And a method in which a polypropylene resin is extruded and laminated in the molten state on the surface of an a layer made of a polypropylene copolymer containing a polymer component (component B) and (3) a heavy component having a structural unit derived from propylene as a main component From a polypropylene-based copolymer containing a coalescing component (component A) and a polymer component (component B) of propylene, ethylene and an α-olefin having 4 or more carbon atoms That a method in which laminating a layer surface by b layer adhesive consisting of polypropylene resins.

In addition, the multilayer film of the present invention can be used as at least one layer of a composite film in which the multilayer film of the present invention is laminated on another film. Examples of the other film include a polypropylene biaxially stretched film, an unstretched or stretched nylon film, a stretched polyterephthalate ethyl film, and an aluminum stay. As a method of laminating the multilayer film of the present invention on the other film, Examples thereof include a dry laminating method and an extrusion laminating method.
The multilayer film of the present invention is suitably used for retort food packaging applications that are subjected to heat treatment at high temperatures.

If necessary, additives and other resins may be added to the polypropylene copolymer and the polypropylene resin used in the present invention. Examples of the additive include an antioxidant, an ultraviolet absorber, an antistatic agent, a lubricant, a nucleating agent, an adhesive, an antifogging agent, an antiblocking agent, and an organic peroxide. Examples of other resins include high-density polyethylene, linear low-density polyethylene, low-density polyethylene, and elastomers that are copolymers of ethylene and α-olefin, which are manufactured using heterogeneous catalysts. Alternatively, it may be produced with a homogeneous catalyst (for example, a metallocene catalyst). Further, an elastomer such as a styrene copolymer rubber obtained by hydrogenating a styrene-butadiene-styrene copolymer or a styrene-isoprene-styrene copolymer may be added.

Hereinafter, although the present invention is explained using an example and a comparative example, the range of the present invention is not limited only to an example. The detailed description of the invention and the measured values of each item in the examples and comparative examples were measured by the following methods.

(1) Melting temperature (unit: ° C)
About 10 mg of the test piece was melted at 220 ° C. under a nitrogen atmosphere using a differential scanning calorimeter (Perkin Elmer DSC), and then rapidly cooled to 150 ° C. After holding at 150 ° C. for 1 minute, the temperature was lowered to 50 ° C. at a rate of 5 ° C./min. Thereafter, the temperature was held at 50 ° C. for 1 minute, and then the temperature was raised at 5 ° C./minute, and the temperature of the maximum peak of the obtained melting endothermic curve was defined as the melting temperature (Tm). Note that the melting point of indium (In) measured at a rate of temperature increase of 5 ° C./min using this measurement method was 156.6 ° C.

(2) MFR (unit: g / 10 minutes)
According to JIS K7210, measurement was performed at a temperature of 230 ° C. and a load of 2.16 kgf.

(3) Intrinsic viscosity ([η], unit: dL / g)
The measurement was performed in 135 ° C. tetralin using an Ubbelohde viscometer.

(4) Weight ratio χ (unit:% by weight) of component B to the entire polypropylene copolymer
Polymerization ratio: χ of the polymer component (component B) of propylene, ethylene, and α-olefin having 4 or more carbon atoms to the entire polypropylene copolymer containing component A and component B was calculated by the following method. .
χ = 1−ΔH _B / ΔH _A
ΔH _A : Polymer part (component A) whose structural unit derived from propylene is the main component (component A) heat of fusion of polymer after polymerization (J / g)
ΔH _B : Polymer component of propylene, ethylene and α-olefin having 4 or more carbon atoms (component B) Heat of fusion of polymer after polymerization (J / g)

(5) Content of structural unit derived from ethylene of component B (Y) and content of structural unit derived from 1-butene (Z) (unit: wt%)
Content of structural unit derived from ethylene (C2 ′ (T)) in polypropylene-based copolymer containing component A and component B and content of structural unit derived from 1-butene (C4 ′ (T) ) Was determined by the method described on pages 616 to 619 of the Polymer Analysis Handbook (1995, published by Kinokuniya Shoten).
Next, C2 ′ (T), C4 ′ (T) and χ described in the above (5) are derived from the content (Y) of structural unit derived from ethylene of component B and 1-butene by the following method. The content (Z) of the structural unit was calculated.
Y = C2 ′ (T) / χ × 100
Z = C4 ′ (T) / χ × 100

(6) Sliding property: Static friction coefficient (unit: μs) and dynamic friction coefficient (unit: μk)
At the room temperature of 23 ° C and humidity of 50%, the measurement surfaces of two film samples of MD100mm x 50mm are superposed on each other, using a weight of 79.4g with an installation area of 40mm x 40mm, a friction measuring machine manufactured by Toyo Seiki (TR -2 type) at a moving speed of 15 cm / min.

(7) Blocking resistance (unit: kg / 12cm ² )
Using a 150 mm x 30 mm film (collected so that the film forming direction and the long side direction coincided), the films were overlapped, and a load of 500 g was applied to a range of 40 mm x 30 mm at a predetermined temperature (60 ° C). Conditioning was performed for 24 hours. Thereafter, the sample was left in an atmosphere of 23 ° C. and 50% humidity for 30 minutes or more, peeled off at a rate of 200 mm / min using a tensile tester manufactured by Toyo Seiki, and the strength required for peeling the sample was measured.

(8) Impact resistance (unit: kJ / m)
The film was placed in a thermostat set at a predetermined temperature (−15 ° C.), and the impact strength of the film was measured using a Toyo Seiki film impact tester using a hemispherical impact head having a diameter of 15 mm.

Reference Example 1 Production of Polypropylene Copolymer (BCPP1) [Synthesis of Solid Components]
A 200 liter cylindrical reactor (with a stirrer having 3 pairs of stirring blades having a diameter of 0.35 m and 4 baffles having a width of 0.05 m and having a diameter of 0.5 m) was purged with nitrogen, and 54 liters of hexane, 780 g of diisobutyl phthalate, 20.6 kg of tetraethoxysilane and 2.23 kg of tetrabutoxy titanium were added and stirred. Next, 51 liters of dibutyl ether solution of butyl magnesium chloride (concentration 2.1 mol / liter) was dropped into the stirred mixture over 4 hours while maintaining the temperature in the reactor at 5 ° C. At this time, the rotational speed of stirring was 120 rpm. After completion of the dropwise addition, the mixture was stirred at 20 ° C. for 1 hour and filtered. The obtained solid was washed with 70 liters of toluene at room temperature three times, and toluene was added to obtain a solid component slurry.
The solid component contained Ti: 1.9% by weight, OEt (ethoxy group): 35.9% by weight, and OBu (butoxy group): 3.6% by weight. Moreover, the valence of the titanium atom in this solid component was trivalent.
[Synthesis of solid catalyst components]
After a 100 ml flask equipped with a stirrer, a dropping funnel and a thermometer was replaced with nitrogen, the solid component slurry obtained above was charged in an amount containing 8 g of the dry solid component, and the total volume of the slurry was 26. The supernatant liquid was extracted to 5 ml. A mixture of 16.0 ml of titanium tetrachloride and 0.8 ml of dibutyl ether was added at 40 ° C., and a mixture of 2.0 ml of phthalic acid chloride (hereinafter abbreviated as OPC) and 2.0 ml of toluene. Was added dropwise over 5 minutes. After completion of the dropwise addition, the reaction mixture was stirred at 115 ° C. for 4 hours. Thereafter, solid-liquid separation was performed at the same temperature, and washing was performed 3 times at 115 ° C. with 40 ml of toluene.
After washing, toluene was added so that the volume of the slurry was 26.5 ml. Thereto was added a mixture of 0.8 ml of dibutyl ether, 0.45 ml of diisobutyl phthalate and 6.4 ml of titanium tetrachloride, and the mixture was stirred at 105 ° C. for 1 hour. Thereafter, solid-liquid separation was performed at the same temperature, and washing was performed twice at 105 ° C. with 40 ml of toluene.
Next, toluene was added so that the volume of the slurry was 26.5 ml, and the temperature was 105 ° C. Thereto was added a mixture of 0.8 ml of dibutyl ether and 6.4 ml of titanium tetrachloride, and the mixture was stirred at 105 ° C. for 1 hour. Thereafter, solid-liquid separation was performed at the same temperature, and washing was performed twice at 105 ° C. with 40 ml of toluene.
Furthermore, toluene was added to 105 ° C. so that the volume of the slurry was 26.5 ml. Thereto was added a mixture of 0.8 ml of dibutyl ether and 6.4 ml of titanium tetrachloride, and the mixture was stirred at 105 ° C. for 1 hour. Thereafter, solid-liquid separation was performed at the same temperature, followed by washing 6 times with 105 ml of toluene at 105 ° C. and 3 times with 40 ml of hexane at room temperature. This was dried under reduced pressure to obtain a solid catalyst component.
The solid catalyst component contained 1.6% by weight of titanium atoms, 7.6% by weight of diethyl phthalate, 0.8% by weight of ethyl normal butyl phthalate, and 2.5% by weight of diisobutyl phthalate.
[Preliminary polymerization]
To a SUS autoclave with a stirrer with an internal volume of 3 L, 1.5 L of fully dehydrated and degassed n-hexane, 30 mmol of triethylaluminum, 3.0 mmol of cyclohexylethyldimethoxysilane and 16 g of the above solid catalyst component were added, After preliminarily polymerizing 32 g of propylene while continuously maintaining the temperature in the autoclave at about 3 to 20 ° C. over about 40 minutes, the prepolymerized slurry was transferred to a 200-liter SUS autoclave with a stirrer. Then, 132 L of liquid butane was added to prepare a slurry of a prepolymerized catalyst component.
Polymerization of component A [polymerization step (1)]
A slurry of propylene, hydrogen, triethylaluminum, cyclohexylethyldimethoxysilane and a prepolymerization catalyst component was continuously fed using a vessel type reactor having an internal volume of 40 L with a stirrer, polymerization temperature: 78 ° C., stirring speed: 150 rpm, Reactor liquid level: 18 L, propylene: 25 kg / hr, hydrogen: 19 NL / hr, triethylaluminum feed: 41 mmol / hr, cyclohexylethyldimethoxysilane feed: 6.15 mmol / hr, prepolymerization Supply amount of catalyst component slurry: Continuous polymerization was performed for 0.26 hours under the condition of 0.45 g / hour as a solid catalyst component conversion. The discharged polymer was 2.4 kg / hour.
[Polymerization step (2)]
The slurry discharged from the polymerization step (1) is continuously transferred to a vessel type reactor different from the polymerization step (1), and propylene and hydrogen are continuously supplied. Polymerization temperature: 73 ° C., stirring speed : 150 rpm, liquid level of the reactor: 44 L was maintained, and continuous polymerization was further performed for 0.45 hours under the conditions of propylene: 15 kg / hour and hydrogen: 10 NL / hour. The discharged polymer was 3.5 kg / hour.
[Polymerization step (3)]
The slurry discharged from the polymerization step (2) is continuously transferred to a vessel type reactor different from the polymerization steps (1) and (2), polymerization temperature: 68 ° C., stirring speed: 150 rpm, reactor liquid Level: 44 L was maintained, and further continuous polymerization was performed for 0.49 hours. The discharged polymer was 3.4 kg / hour.
[Polymerization step (4)]
The slurry discharged from the polymerization step (3) is continuously transferred to a fluidized bed reactor with an internal volume of 1 m ³ and equipped with a stirrer, and propylene and hydrogen are continuously supplied. Polymerization temperature: 80 ° C., polymerization pressure: 1 Polymerization was carried out for 2.3 hours at a concentration ratio of propylene and hydrogen in the reactor gas of 8 MPa, 99.99 vol% / 1.01 vol% (propylene concentration / hydrogen concentration). The polymer was discharged at 8.0 kg / hour. The intrinsic viscosity [η] A of the obtained polymer component (component A) was 1.7 dL / g.
Polymerization of component B [polymerization step (5)]
The polymer component (component A) discharged from the polymerization step (4) is continuously transferred to a fluidized bed reactor with a stirrer having an internal volume of 1 m ³ different from the reactor used in the polymerization step (4). Propylene, ethylene, 1-butene and hydrogen are continuously supplied, polymerization temperature: 70 ° C., polymerization pressure: 1.4 MPa, concentration ratio of propylene, ethylene, 1-butene and hydrogen in the reactor gas: 31.52 Volume% / 45.9 volume% / 19.8 volume% / 2.78 volume% (propylene concentration / ethylene concentration / 1-butene concentration / hydrogen concentration), moles of triethylaluminum supplying oxygen as a deactivator Polymerization was performed for 3.3 hours under the condition of adding 0.004 as a ratio. The polymer was discharged at 4.0 kg / hour. The intrinsic viscosity [η] B of the obtained polymer component (component B) was 3.4 dL / g.
Table 1 shows the analysis results of each component of the produced polypropylene copolymer.

Reference Example 2 Production of Polypropylene Copolymer (BCPP2) The solid catalyst component and prepolymerization were carried out in the same steps as in Reference Example 1.
Polymerization of component A [polymerization step (1)]
A slurry of propylene, hydrogen, triethylaluminum, cyclohexylethyldimethoxysilane and a prepolymerization catalyst component was continuously fed using a vessel type reactor having an internal volume of 40 L with a stirrer, polymerization temperature: 78 ° C., stirring speed: 150 rpm, Reactor liquid level: 18 L, propylene: 25 kg / hr, hydrogen: 19 NL / hr, triethylaluminum feed: 41 mmol / hr, cyclohexylethyldimethoxysilane feed: 6.15 mmol / hr, prepolymerization Supply amount of catalyst component slurry: Continuous polymerization was carried out for 0.27 hours under the condition of 0.43 g / hour in terms of solid catalyst component. The discharged polymer was 2.3 kg / hour.
[Polymerization step (2)]
The slurry discharged from the polymerization step (1) is continuously transferred to a vessel type reactor different from the polymerization step (1), and propylene and hydrogen are continuously supplied. Polymerization temperature: 73 ° C., stirring speed : 150 rpm, liquid level of the reactor: 44 L was maintained, and continuous polymerization was further performed for 0.46 hours under the conditions of propylene: 15 kg / hour, hydrogen: 10 NL / hour. The discharged polymer was 3.4 kg / hour.
[Polymerization step (3)]
The slurry discharged from the polymerization step (2) is continuously transferred to a vessel type reactor different from the polymerization steps (1) and (2), polymerization temperature: 68 ° C., stirring speed: 150 rpm, reactor liquid Level: 44 L was maintained, and continuous polymerization was further performed for 0.50 hours. The discharged polymer was 3.2 kg / hour.
[Polymerization step (4)]
The slurry discharged from the polymerization step (3) is continuously transferred to a fluidized bed reactor with an internal volume of 1 m ³ and equipped with a stirrer, and propylene and hydrogen are continuously supplied. Polymerization temperature: 80 ° C., polymerization pressure: 1 Polymerization was performed for 3.1 hours at a ratio of propylene and hydrogen in the reactor gas of .8 MPa and a concentration ratio of 99.04 vol% / 0.96 vol% (propylene concentration / hydrogen concentration). The polymer was discharged at 7.3 kg / hour. The intrinsic viscosity [η] A of the obtained polymer component (component A) was 1.7 dL / g.
Polymerization of component B [polymerization step (5)]
The polymer component (component A) discharged from the polymerization step (4) is continuously transferred to a fluidized bed reactor with a stirrer having an internal volume of 1 m ³ different from the reactor used in the polymerization step (4). Propylene, ethylene, 1-butene and hydrogen are continuously fed, polymerization temperature: 70 ° C., polymerization pressure: 1.4 MPa, concentration ratio of propylene, ethylene, 1-butene and hydrogen in the reactor gas: 27.77 Volume% / 50 volume% / 20.3 volume% / 1.93 volume% (propylene concentration / ethylene concentration / 1-butene concentration / hydrogen concentration), molar ratio to triethylaluminum supplying oxygen as a deactivator It added as 0.006 and superposition | polymerization was performed for 2.5 hours. The polymer was discharged at 4.1 kg / hour. The intrinsic viscosity [η] B of the obtained polymer component (component B) was 4.4 dL / g.
Table 1 shows the analysis results of each component of the produced polypropylene copolymer.

Reference Example 3 Production of Polypropylene Copolymer (BCPP3) The solid catalyst component and prepolymerization were carried out in the same steps as in Reference Example 1.
Polymerization of component A [polymerization step (1)]
A slurry of propylene, hydrogen, triethylaluminum, cyclohexylethyldimethoxysilane and a prepolymerization catalyst component was continuously fed using a vessel type reactor having an internal volume of 40 L with a stirrer, polymerization temperature: 78 ° C., stirring speed: 150 rpm, Reactor liquid level: 18 L, propylene: 25 kg / hr, hydrogen: 20 NL / hr, triethylaluminum feed rate: 42 mmol / hr, cyclohexylethyldimethoxysilane feed rate: 6.3 mmol / hr, prepolymerization Supply amount of catalyst component slurry: Continuous polymerization was carried out for 0.26 hours under the condition of 0.57 g / hour in terms of solid catalyst component. The discharged polymer was 2.5 kg / hour.
[Polymerization step (2)]
The slurry discharged from the polymerization step (1) is continuously transferred to a vessel type reactor different from the polymerization step (1), and propylene and hydrogen are continuously supplied. Polymerization temperature: 73 ° C., stirring speed : 150 rpm, liquid level of the reactor: 44 L was maintained, and continuous polymerization was further performed for 0.45 hours under the conditions of propylene: 15 kg / hour and hydrogen: 11 NL / hour. The discharged polymer was 3.1 kg / hour.
[Polymerization step (3)]
The slurry discharged from the polymerization step (2) is continuously transferred to a vessel type reactor different from the polymerization steps (1) and (2), polymerization temperature: 68 ° C., stirring speed: 150 rpm, reactor liquid Level: 44 L was maintained, and further continuous polymerization was performed for 0.49 hours. The discharged polymer was 2.7 kg / hour.
[Polymerization step (4)]
The slurry discharged from the polymerization step (3) is continuously transferred to a fluidized bed reactor with an internal volume of 1 m ³ and equipped with a stirrer, and propylene and hydrogen are continuously supplied. Polymerization temperature: 80 ° C., polymerization pressure: 1 Polymerization was carried out for 2.9 hours at a ratio of propylene to hydrogen in the reactor gas of 0.8 MPa: 98.91 vol% / 1.09 vol% (propylene concentration / hydrogen concentration). The discharged polymer component (component A) was 10.9 kg / hour, and the intrinsic viscosity [η] A of the obtained polymer component (component A) was 1.8 dL / g.
Polymerization of component B [polymerization step (5)]
The polymer component (component A) discharged from the polymerization step (4) is continuously transferred to a fluidized bed reactor with a stirrer having an internal volume of 1 m ³ different from the reactor used in the polymerization step (4). Propylene, ethylene and hydrogen are continuously fed, polymerization temperature: 70 ° C., polymerization pressure: 1.4 MPa, concentration ratio of propylene, ethylene and hydrogen in the reactor gas: 74.72% by volume / 24% by volume / 1 .28 volume% (propylene concentration / ethylene concentration / hydrogen concentration), oxygen as a deactivator was added at a molar ratio of 0.017 to the supplied triethylaluminum, and polymerization was carried out for 1.9 hours. The discharged polymer component (component B) was 5.0 kg / hour, and the intrinsic viscosity [η] B of the obtained polymer component (component B) was 2.6 dL / g.
Table 1 shows the analysis results of each component of the produced polypropylene polymer.

Example 1
7 g of polypropylene copolymer (BCPP1), 3.5 g of calcium stearate as a stabilizer, Irganox 1010 (manufactured by Ciba Specialty Chemicals) 14 g, Irgafos 168 (manufactured by Ciba Specialty Chemicals) 3.5 g Was added and melt kneaded at 250 ° C. using a 40 mm single screw extruder (VS40-28 type: manufactured by Tanabe Plastics Machine Co., Ltd., with a full flight screw), and MFR = 2.8 (g / 10 min). Pellets were obtained.
Next, with respect to 7 kg of the polypropylene copolymer (BCPP3), 3.5 g of calcium stearate as a stabilizer, Irganox 1010 (manufactured by Ciba Specialty Chemicals) 14 g, Irgaphos 168 (manufactured by Ciba Specialty Chemicals) 3.5 g was added and melt-kneaded at 250 ° C. using a 40 mm single screw extruder (VS40-28 type: Tanabe Plastics Machine Co., Ltd., with full flight type screw), MFR = 2.7 (g / 10 minutes) pellets were obtained.
Regarding film formation, pellets of BCPP3 were used as the resin of the (b) layer corresponding to both surface layers, the diameter was 40 mm, L / D was 32 (L is the length of the cylinder of the extruder, D is the cylinder of the extruder) The resin was melted and kneaded at 280 ° C. using two extruders having a diameter) and then led to both surface layer sides of the feed block. (A) Corresponding to the inner layer, BCPP1 pellets are used as the resin of the layer, and after melt-kneading the resin at 280 ° C. using one extruder having a diameter of 50 mm and L / D of 32, the inner layer side of the feed block Led to. These resins that passed through the feed block were extruded from a T-die (600 mm width) adjusted to 280 ° C., and then cooled and solidified by pulling with a chill roll at 50 ° C., and a multilayer film having a total thickness of 60 μm was 20 m / min. The paper tube was wound at a line speed. The thickness of each layer of the obtained multilayer film was (b) layer thickness / (a) layer thickness / (b) layer thickness = 10 μm / 40 μm / 10 μm. Table 3 shows the physical properties of the resulting multilayer film.

Example 2
(B) The same as in Example 1 except that a propylene-ethylene copolymer (Nobrene FH3315 manufactured by Sumitomo Chemical Co., Ltd., MFR = 3.0 g / 10 min, melting temperature = 144 ° C.) was used as the resin for the layer. A multilayer film was obtained by this method. Table 3 shows the physical properties of the resulting multilayer film.

Example 3
(B) In the same manner as in Example 1 except that a propylene homopolymer (Nobrene FLX80E4 manufactured by Sumitomo Chemical Co., Ltd., MFR = 7.5 g / 10 min, melting temperature = 163 ° C.) was used as the resin for the layer. A multilayer film was obtained. Table 3 shows the physical properties of the resulting multilayer film.

Example 4
7 g of polypropylene copolymer (BCPP2), 3.5 g of calcium stearate as a stabilizer, Irganox 1010 (manufactured by Ciba Specialty-Chemicals) 14 g, Irgaphos 168 (manufactured by Ciba Specialty-Chemicals) 3.5 g Was added and melt-kneaded at 250 ° C. using a 40 mm single screw extruder (VS40-28 type: Tanabe Plastics Machine Co., Ltd., with full flight type screw), MFR = 2.6 (g / 10 min) Pellets were obtained.
Regarding film formation, propylene homopolymer (Nobrene FLX80E4 manufactured by Sumitomo Chemical Co., Ltd., MFR = 7.5 g / 10 min, melting temperature = 163 ° C.) is used as the resin for the layer (b), and the resin for the layer (a). A multilayer film was obtained in the same manner as in Example 1 except that BCPP2 pellets were used. Table 3 shows the physical properties of the resulting multilayer film.

Comparative Example 1
(B) Propylene homopolymer (Nobrene FLX80E4 manufactured by Sumitomo Chemical Co., Ltd., MFR = 7.5 g / 10 min, melting temperature = 163 ° C.) is used as the layer resin, and (a) BCPP3 pellets are used as the layer resin. A multilayer film was obtained in the same manner as in Example 1 except that it was used. Table 3 shows the physical properties of the resulting multilayer film.

Comparative Example 2
A multilayer film was obtained in the same manner as in Example 1 except that BCPP3 pellets were used for both the resin in the (b) layer and the resin in the (a) layer. Table 3 shows the physical properties of the resulting multilayer film.

Comparative Example 3
For film formation, a propylene homopolymer (Nobrene FS2011DG3 manufactured by Sumitomo Chemical Co., Ltd., MFR = 2.5 g / 10 min, melting temperature = 158 ° C.) is used as the resin of the layer (b) corresponding to both surface layers, Was melt-kneaded at 280 ° C. using two extruders having a length of 40 mm and an L / D of 32 (L is the length of the cylinder of the extruder, and D is the diameter of the cylinder of the extruder). It led to both surface layer side. (A) Corresponding to the inner layer, BCPP1 pellets are used as the resin of the layer, and after melt-kneading the resin at 280 ° C. using one extruder having a diameter of 50 mm and L / D of 32, the inner layer side of the feed block Led to. These resins that passed through the feed block were extruded from a T-die (600 mm width) adjusted to 280 ° C., and then cooled and solidified by pulling with a chill roll at 50 ° C., and a multilayer film having a total thickness of 60 μm was 20 m / min. The paper tube was wound at a line speed. The thickness of each layer of the obtained multilayer film was (b) layer thickness / (a) layer thickness / (b) layer thickness = 20 μm / 20 μm / 20 μm. Table 3 shows the physical properties of the resulting multilayer film.

Comparative Example 4
The thickness of each layer of the obtained multilayer film was the same as Comparative Example 3 except that (b) layer thickness / (a) layer thickness / (b) layer thickness = 25 μm / 10 μm / 25 μm. A multilayer film was obtained. Table 3 shows the physical properties of the resulting multilayer film.

Comparative Example 5
(B) The same method as in Comparative Example 4 except that a propylene homopolymer (Nobrene FLX80E4 manufactured by Sumitomo Chemical Co., Ltd., MFR = 7.5 g / 10 min, melting temperature = 163 ° C.) was used as the resin for the layer. A multilayer film was obtained. Table 3 shows the physical properties of the resulting multilayer film.

Comparative Example 6
(A) A multilayer film was obtained in the same manner as in Comparative Example 4 except that BCPP2 pellets were used as the resin for the layer. Table 3 shows the physical properties of the resulting multilayer film.

Comparative Example 7
The propylene-ethylene copolymer (Nobrene FH3315 manufactured by Sumitomo Chemical Co., Ltd., MFR = 3.0 g / 10 min, melting temperature = 144 ° C.) was used for both the resin of layer (b) and the resin of layer (a). Obtained a multilayer film in the same manner as in Example 1. Table 3 shows the physical properties of the resulting multilayer film.

Comparative Example 8
The propylene homopolymer (Nobrene FS2011DG3 manufactured by Sumitomo Chemical Co., Ltd., MFR = 2.5 g / 10 min, melting temperature = 158 ° C.) was used for both the resin of the layer (b) and the resin of the layer (a). A multilayer film was obtained in the same manner as in Example 1. Table 3 shows the physical properties of the resulting multilayer film.

Table 1

Table 2

Table 3

Claims (2)

Polymer component “component A” having a structural unit derived from propylene as a main component, 50 to 95% by weight,
The content (X) of the structural unit derived from propylene is 10 ≦ X <50% by weight,
The content (Y) of the structural unit derived from ethylene is 50 <Y ≦ 70% by weight,
Content (Z) of structural unit derived from α-olefin having 4 or more carbon atoms is 0 <Z ≦ 20% by weight (provided that the total of X, Y and Z is 100% by weight), and derived from propylene The weight ratio of the content (Z) of the structural unit derived from the α-olefin having 4 or more carbon atoms to the content (X) of the structural unit is 1 or less.
On at least one side of the a layer containing a polypropylene-based copolymer containing 5 to 50% by weight of a polymer component (component B) of propylene, ethylene and an α-olefin having 4 or more carbon atoms,
A multilayer film comprising a b layer made of a polypropylene resin other than the polypropylene copolymer and a thickness ratio (a layer / b layer) of greater than 1. The multilayer film according to claim 1, wherein the α-olefin having 4 or more carbon atoms is 1-butene.