JPH11302475A - Polypropylene based resin composition and packaging film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain polypropylene based resin compositions which give films excellent in clarity, impact resistance, low temperature sealing properties, heat sealing strength and food hygienic properties, and to prepare packaging films and food packaging films using the same. SOLUTION: Desired polypropylene based resin compositions comprise (I) 40-95 wt.% crystalline propylene/α-olefin copolymer and (II) 5-60 wt.% propylene based block copolymer component comprising a copolymer component (component A) composed of at least propylene units and ethylene units and/or butene-1 units and a copolymer component (component B) composed of propylene units and ethylene units and/or butene-1 units and having a structure different from the structure of component A and a content of xylene-soluble portions (CXS portion) at 20 deg.C of not less than 5 wt.% and a maximum melting peak temperature (Tm) of the portions (CXIS) excluding the CXS portions, measured by a differential scanning calorimeter, of 130-155 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film for food packaging which is excellent in transparency, impact strength at low temperature, heat sealability, heat seal strength and food hygiene.

[0002]

2. Description of the Related Art Polypropylene resin films are widely used in the field of packaging such as food packaging and textile packaging because of their excellent appearance, mechanical properties and packaging suitability. Although propylene homopolymer has excellent transparency and heat resistance,
Impact resistance at low temperatures and low-temperature heat-sealing properties are inferior.Although propylene-α-olefin random copolymers have improved low-temperature heat-sealing properties, low-temperature impact resistance is inferior, and propylene block copolymers are Although it has excellent low-temperature impact resistance to some extent, transparency and low-temperature heat sealability are inferior, and each has its limitations.

[0003] For these reasons, a material having an impact resistance obtained by blending a low-crystalline ethylene-α-olefin copolymer with a propylene-α-olefin random copolymer is generally used. . However, there is a problem that blending a low-crystalline ethylene-α-olefin copolymer with a propylene-α-olefin random copolymer lowers the heat seal strength.

[0004] A film for food packaging having excellent transparency, impact resistance, low-temperature heat sealability, heat seal strength and food hygiene has not been obtained by the conventionally known methods.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a polypropylene-based resin composition which gives a film having excellent transparency, impact resistance, low-temperature heat sealability, heat seal strength, and food hygiene. An object of the present invention is to provide a packaging film and a food packaging film.

[0006]

Means for Solving the Problems The present inventors have proposed transparency,
As a result of intensive studies on a polypropylene-based resin composition that gives a film excellent in impact resistance, low-temperature heat sealability, heat seal strength, and food hygiene, it was found that crystalline propylene and ethylene and / or α- The present inventors have found that a polypropylene-based resin composition containing a copolymer of olefin and a specific propylene-based block copolymer achieves the object of the present invention, and completed the present invention.

That is, the present invention relates to a copolymer (I) comprising 40 to 95% by weight of a copolymer of crystalline propylene with ethylene and / or an α-olefin having 4 or more carbon atoms and at least a repeating unit derived from propylene and ethylene. Component (A) comprising a repeating unit derived from styrene and / or a repeating unit derived from butene-1, and a repeating unit derived from propylene and a repeating unit derived from ethylene and / or butene A propylene-based block copolymer comprising a copolymer component (component B) having a repeating unit derived from -1 and having a structure different from that of the component A, wherein the xylene-soluble portion (CXS portion) at 20 ° C. Wt% or more and the maximum melting peak temperature of the portion (CXIS portion) excluding the CXS portion measured by a differential scanning calorimeter Propylene block copolymer Tm) is 130~155 ℃ (II) 5~60 wt%
And a packaging film and a food packaging film using the same.
Hereinafter, the present invention will be described in detail.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The copolymer (I) of crystalline propylene and ethylene and / or an α-olefin having 4 or more carbon atoms used in the present invention has a melting point of 130 to 150 ° C.
Propylene and ethylene and / or butene-1, hexene-1,
Alternatively, a copolymer with octene-1 is preferred. Melting point is 1
If it is lower than 30 ° C., the heat resistance is insufficient, and if it is higher than 150 ° C., the low-temperature heat sealability deteriorates.

The copolymer (I) of crystalline propylene and ethylene and / or an α-olefin having 4 or more carbon atoms used in the present invention has, for example, a Ziegler-Natta type catalyst and a cyclopentadienyl ring. Periodic Table IVB
A catalyst system comprising a transition metal compound of group III and an alkylaluminoxane, or a catalyst comprising a transition metal compound of group IVB having a cyclopentadienyl ring and a compound which reacts therewith to form an ionic complex and an organoaluminum compound Using the system, production can be carried out by a batch polymerization method, a continuous polymerization method of continuously polymerizing, or the like.

[0010] Specifically, for example, the presence of an organic silicon compound having a (a) Si-O bonds, the general formula _{Ti (OR 1) nX 4 -n} (R 1 has a carbon number 1
To 20 hydrocarbon groups, X is a halogen atom, and n is 0 <n ≦
Represents the number 4. A) a solid product obtained by reducing the titanium compound represented by the formula (1) with an organomagnesium compound, and treating the solid product with a mixture of an ester compound and an ether compound with titanium tetrachloride; (B) an 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); or (a) a general formula Ti (OR ₁ ) nX ₄ -n (R ₁ is a hydrocarbon group having 1 to 20 carbon atoms, X is a halogen electron, n is 0 <n
≤4. )
Reduction with an organoaluminum compound represented by the general formula AlR ₂ mY ₃ -m (R ₂ is a hydrocarbon group having 1 to 20 carbon atoms, Y is a halogen electron, and m is a number of 1 ≦ m ≦ 3). The obtained solid product containing a hydrocarbyloxy group insoluble in a hydrocarbon solvent is prepolymerized with ethylene, and then heated to a temperature of 80 to 100 ° C. in a hydrocarbon solvent in the presence of an ether compound and titanium tetrachloride. Using a hydrocarbyloxy group-containing solid catalyst component obtained by treating the slurry in a slurry state with a Ziegler-Natta type catalyst containing at least titanium, magnesium and halogen as essential components such as a catalyst system comprising (b) an organoaluminum compound. The molar ratio of Al atoms in the component (b) / Ti atoms in the component (a) is from 1 to 2000, preferably from 5 to 1500;
The molar ratio of Al atoms in component (c) / component (b) is set to 0.0
The polymerization temperature is 20 to 150 ° C, preferably 50 to 95 ° C.
° C., the polymerization pressure is atmospheric pressure ~40Kg / cm ² G, preferably under conditions of 2~40Kg / cm ² G, propylene and ethylene and / or α- olefin and molecular weight in the absence of a substantially inert solvent It can be produced by supplying hydrogen for control and polymerizing.

The propylene-based block copolymer (II) used in the present invention comprises at least a repeating unit derived from propylene (hereinafter referred to as "propylene unit") and a repeating unit derived from ethylene (hereinafter referred to as "ethylene unit"). ") And / or a repeating unit derived from butene-1 (hereinafter referred to as" butene-1 unit "), a propylene unit, an ethylene unit and / or butene. A propylene-based block copolymer comprising a copolymer component (component B) comprising -1 unit and having a structure different from that of the component A,
The maximum melting peak temperature (5% by weight or more, preferably 7 to 30% by weight) of the xylene-soluble portion (CXS portion) at 20 ° C., which is measured by a differential scanning calorimeter, of the portion excluding the CXS portion (CXIS portion) ( Tm) is a propylene-based block copolymer having a temperature of 130 to 155 ° C. The propylene-based block copolymer (II) according to the present invention comprises a propylene-ethylene and / or butene-1 copolymer component in the first step and a propylene-ethylene having a different structure in the second step. And / or a copolymer component obtained by successively polymerizing a copolymer component comprising butene-1, wherein a typical block copolymer in which a copolymer terminal and another copolymer terminal are connected by a bond. It is not a coalesced but a kind of blended copolymer.

When the CXS content of the propylene-based block copolymer is less than 5.0% by weight, the impact resistance of the film using the same is inferior.

CXIS of propylene-based block copolymer
When the maximum melting peak temperature (Tm) measured by a differential scanning calorimeter (DSC) is less than 130 ° C., the heat resistance of the film using the same is insufficient. It is not preferable because it is inferior.

For example, in the first step, the propylene-ethylene copolymer portion (component A) having an ethylene unit content of 1.5 to 6.0% by weight is converted into the total polymerization amount (total of component A and component B below). Of the propylene-ethylene copolymer portion (component B) having a content of ethylene unit of 7 to 17% by weight in the second step (total amount of component A and component B). A block copolymer obtained by producing 15 to 60% by weight of the component ( _B ), wherein the intrinsic viscosity ([η] _B ) of the component B is 2 to 5 dl / g, and the intrinsic viscosity ([η] _B ) of the component _B is A propylene block copolymer having a ratio ([η] _B / [η] _A ) to the intrinsic viscosity ([η] _A ) of the component _A of 0.5 to 1.8 is preferable.

The ethylene unit content is measured by the ¹³ C-NMR method according to the method described on page 616 of a Handbook for Polymer Analysis (1995, published by Kinokuniya Bookstore). The ethylene unit content (EA) of the component _A is analyzed by sampling the copolymer after the completion of the polymerization in the first step. The ethylene content (E _B ) of the component _B is determined by sampling the block copolymer after completion of the polymerization in the second step, analyzing the ethylene content (E _AB ) of the block copolymer, and further calculating the proportion of the component A (P B). _A ) and the ratio of the B component (P _B ) are determined by the following equation. _{E A × P A / 100 +} E B × P B / 100 = E AB E B = (E AB -E A × P A / 100) × 100 / P B

In the case of the propylene-ethylene-butene-1 block copolymer, the ratio of the component _A (P _A ) and the ratio of the component _B (P _B ) are measured with a differential scanning calorimeter for the component A and the whole polymer. It is determined from the respective melting peak calories. Content of ethylene unit of component _A (EA)
The content of butene-1 unit (B _A ) of the component _A is analyzed by sampling the copolymer after completion of the polymerization in the first step. Further, the content of the ethylene unit of the component _B (E _B )
And the content of butene-1 unit (B _B ) of the component _B were determined by first sampling the block copolymer after the completion of the polymerization in the second step, and measuring the content of ethylene unit (E _AB ) and the content of butene-1 unit. The amount (B _AB ) was determined by analysis, and the ratio of the component _A (P _A ) and the ratio of the component _B (P _B ), the content of the ethylene unit of the component _A (EA) and the butene-1 unit of the component A It is determined from the content (B _A ) by the following equation. _{E B = (E AB -E A} × P A / 100) × 100 / P B B B = (B AB -B A × P A / 100) × 100 / P B

The intrinsic viscosity is measured at 135 ° C. in tetralin using an Ubbelohde viscometer. The intrinsic viscosity ([η] _A ) of the component _A is analyzed by sampling the copolymer after the completion of the polymerization in the first step. Intrinsic viscosity of component B ([η]
_B ) samples the block copolymer after completion of the polymerization in the second step, analyzes the intrinsic viscosity ([η] _AB ) of the block copolymer, and further analyzes the ratio of the A component (P _A ),
It is determined from the following equation from the ratio (P _B ) of the B component. [Η] _A × P _A / 100 + [η] _B × P _B / 100 = [η]
_AB [η] _B = ([η] _AB- [η] _A × P _A / 100) × 10
0 / P _B

The propylene-based block copolymer (II) used in the present invention is obtained by, for example, polymerizing component A in the same polymerization tank in the presence of a Ziegler-Natta type catalyst, and then continuously polymerizing component B. It can be produced by a formula polymerization method or a continuous polymerization method of continuously polymerizing the component A and the component B using a polymerization tank having at least two tanks.

Specifically, for example, in the presence of (a) an organosilicon compound having a Si—O bond, a compound represented by the general formula Ti (OR
¹ ) A titanium compound and / or an ether compound represented by _n X _4-n (R ¹ is a hydrocarbon group having 1 to 20 carbon atoms, X is a halogen atom, and n is a number satisfying 0 <n ≦ 4). A trivalent titanium compound-containing solid catalyst component obtained by treating a solid product obtained by reducing with an organomagnesium compound with a mixture of an ester compound and an ether compound with titanium tetrachloride; (b) an organoaluminum compound (c) Si-oR ² bonds (R ² is a hydrocarbon group having 1 to 20 carbon atoms.) the catalyst system consisting of a silicon compound having, or (a) 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 atom, n is a number satisfying 0 <n ≦ 4), and a titanium compound represented by the general formula AlR ² _m Y _3-m (R ² is a hydrocarbon group having 1 to 20 carbon atoms, Y is And a solid product containing a hydrocarbyloxy group insoluble in a hydrocarbon solvent obtained by reduction with an organoaluminum compound represented by the following formula: After the polymerization treatment, a hydrocarbyloxy group-containing solid catalyst component obtained by treating in a slurry state at a temperature of 80 to 100 ° C. in the presence of an ether compound and titanium tetrachloride in a hydrocarbon solvent, (b) an organoaluminum compound In the presence of a Ziegler-Natta type catalyst comprising titanium, magnesium and halogen as essential components, such as a catalyst system comprising a catalyst system, the molar ratio of Al atom in component (b) / Ti atom in component (a) is 1 to 2000, preferably 5 to 1500,
The molar ratio of Al atoms in component (c) / component (b) is set to 0.0
The polymerization temperature is 20 to 150 ° C, preferably 50 to 95 ° C.
° C., the polymerization pressure is atmospheric pressure ~40kg / cm ² G, preferably under conditions of 2~40kg / cm ² G, and supplies the hydrogen to propylene and ethylene and the molecular weight regulator in the first step propylene - ethylene copolymer After the production of the polymer portion (component A), propylene, ethylene and hydrogen are supplied in the second step to produce the propylene-ethylene copolymer portion (component B).

The copolymer (I) and the propylene block copolymer (II) of crystalline propylene and ethylene and / or an α-olefin having 4 or more carbon atoms used in the present invention are prepared in the presence of an organic peroxide. It is possible to change the fluidity typified by, for example, the melt flow rate in the absence of any known method. Further, if necessary, an antioxidant, an ultraviolet absorber, an antistatic agent, an antiblocking agent, an antifogging agent and the like can be contained.

Crystalline propylene and α-carbon having 4 or more carbon atoms
The copolymer (I) with an olefin and the propylene-based block copolymer (II) each have a melt flow rate in the range of 1.0 to 10 g / 10 min. From 1 to 5
A range of g / 10 minutes is preferred.

The proportions of the copolymer (I) and the propylene block copolymer (II) of crystalline propylene and ethylene and / or an α-olefin having 4 or more carbon atoms used in the present invention are 40 to 95, respectively. % By weight and 5-6
0% by weight, preferably 50 to 90% by weight and 10 to 10% by weight.
50% by weight.

When the amount of the polypropylene copolymer (I) is less than 40% by weight, the heat resistance deteriorates, and when it exceeds 95% by weight, the low-temperature impact resistance decreases.

The resin composition of the present invention has a low content other than the copolymer (I) and the propylene block copolymer (II) of crystalline propylene and ethylene and / or an α-olefin having 4 or more carbon atoms. It is possible to use a composition containing a crystalline ethylene-α-olefin copolymer. The low-crystalline ethylene-α-olefin copolymer is a copolymer of ethylene and an α-olefin having 3 to 10 carbon atoms, and preferably contains 10% by weight or more of α-olefin. The blending amount of the low-crystalline ethylene-α-olefin copolymer is a composition comprising a copolymer (I) of crystalline propylene and an α-olefin having 4 or more carbon atoms and a propylene-based block copolymer (II). Thing 10
It is possible to add 15 parts by weight or less to 0 parts by weight. If the amount exceeds 15 parts by weight, the heat seal strength decreases.

The polypropylene film is produced from the packaging film and the food packaging film of the present invention by a melt extrusion method such as a T-die film forming method and a tubular film forming method which are generally used in industry. The method is not particularly limited as long as it is a method, but a T-die film forming method in which high-speed film forming is performed by a large film forming machine is preferable.

Although the thickness of the film of the present invention is not particularly limited, it is a film having a thickness of 10 to 500 μm, preferably in the range of 10 to 150 μm. In addition, since it has the above-mentioned preferable characteristics, it is suitably used as at least one layer component in the production of a co-extruded multilayer film. Further, other films, for example, a polypropylene biaxially stretched film, an unstretched and stretched nylon film, a stretched polyethyl terephthalate film or at least a composite film manufactured by a method such as aluminum lamination and dry lamination, or extrusion lamination. It is preferably used as a single layer.
It can be used for heat-resistant applications such as heat treatment in the range of 25 ° C. The film of the polypropylene resin composition of the present invention has excellent appearance, mechanical properties, packaging suitability, and the like, and is therefore used in the field of packaging such as food packaging and textile packaging.

[0027]

Hereinafter, the present invention will be described based on examples.
The present invention is not limited to these examples. Next, methods for measuring physical properties in Examples and Comparative Examples will be described. (1) Ratio of Component A and Component B (% by Weight) The ratio of component _A (P _A ) and the ratio of component _B (P _B ) were determined from the mass balance of the components A and B during polymerization. (2) Intrinsic Viscosity ([η]) Measurement was performed in tetralin at 135 ° C. using an Ubbelohde viscometer. Intrinsic viscosities of components A and B ([η] _A , [η] _B ) Intrinsic viscosities [η] _A measured after completion of polymerization of component A in the first step, and intrinsic viscosities measured after completion of polymerization in the second step From [η] _AB , the ratio of component _A (P _A ), and the ratio of component _B (P _B ), the intrinsic viscosity [η] _B of component _B was determined by the following equation. [Η] _B = ([η] _AB- [η] _A × P _A / 100) × 10
0 / P _B (3) Ethylene Unit Content According to the method described in page 616 of the Polymer Analysis Handbook (1995, published by Kinokuniya Bookstore), ¹³ C
-The measurement was performed by the NMR method. Content of ethylene units of components A and B (E _A , E _B ) Content of ethylene units (E _A ) measured after completion of polymerization of component A in the first step, and measurement after completion of polymerization in the second step. From the content of the ethylene unit (E _AB ), the ratio of the component _A (P _A ), and the ratio of the component _B (P _B ), the content of the ethylene unit of the component _B (EB) was determined by the following equation. . After completely dissolving the _{E B = (E AB -E A} × P A / 100) × 100 / P B (4) 20 ℃ xylene solubles (CXS) polypropylene 5g boiling xylene 500 ml, cooled to 20 ° C. And left for more than 4 hours.
Thereafter, this was separated into a precipitate (CXIS part) and a solution by filtration, the filtrate was dried and dried at 70 ° C. under reduced pressure, and the weight of the obtained solid was measured. (5) Maximum melting peak temperature (Tm) of CXIS part Using a differential scanning calorimeter (DSC manufactured by PerkinElmer), 10 mg of the CXIS part obtained in (7) above was melted at 220 ° C for 5 minutes in a nitrogen atmosphere. After that, the temperature was lowered to 40 ° C. at a rate of 5 ° C./min. Thereafter, the temperature was increased at 5 ° C./min, and the peak temperature of the maximum peak of the obtained melting endothermic curve was defined as the maximum melting peak temperature (Tm) of the CXIS part.
The melting point of indium (In) measured at a heating rate of 5 ° C./min using this measuring instrument was 156.6 ° C. (6) Melt flow rate (MFR) Measured according to JIS K7210 under the condition -14. (7) Transparency (haze) Measured according to JIS K7105. (8) Young's modulus A test piece having a width of 20 mm was sampled from the machine direction (MD), and the tensile tester was used to extract a chuck interval of 60 mm and a tensile speed of 5 mm /
An SS curve was taken in minutes, and the initial elastic modulus was measured. (9) Impact Strength At 0 ° C., the impact strength of the film was measured using a film impact tester manufactured by Toyo Seiki, using a hemispherical impact head having a diameter of 15 mm. (10) Heat sealing strength A 25 mm-wide sealed film obtained by laminating the film surfaces together, applying a load of 2 kg / cm 2 for 2 seconds and applying pressure with a heated heat sealer, leaving the film overnight,
Peeling resistance when peeling at a peeling rate of 200 mm / min and a peeling angle of 180 ° at 3 ° C. was measured. (11) Amount of Hexane Extraction According to the method described in FDA 177.1520 (d) (3) (ii), the n-hexane extraction of a film having a thickness of 60μ was measured at 50 ° C.

Production of Propylene Block Copolymer [Synthesis of Solid Catalyst] After replacing a 200 LSUS reaction vessel equipped with a stirrer with nitrogen, 80 L of hexane, 6.55 mol of tetrabutoxytitanium, and 2.8 of diisobutyl phthalate were obtained.
And 98.9 mol of tetraethoxysilane were added to obtain a uniform solution. Next, a diisobutyl ether solution 51 of butylmagnesium chloride having a concentration of 2.1 mol / L was prepared.
L was gradually added dropwise over 5 hours while maintaining the temperature in the reaction vessel at 5 ° C. After completion of the dropwise addition, the mixture was further stirred at 20 ° C. for 1 hour, then subjected to solid-liquid separation at 20 ° C., and washed three times with 70 L of toluene. Then, the slurry concentration was 0.2 kg /
After adding toluene so as to obtain L, 47.6 mol of diisobutyl phthalate was added, and the mixture was reacted at 95 ° C. for 30 minutes. After the reaction, the mixture was separated into solid and liquid, and washed twice with toluene. Next, 3.13 mol of diisobutyl phthalate, 8.9 mol of butyl ether and 274 mol of titanium tetrachloride were added, and the mixture was reacted at 105 ° C. for 3 hours. After the completion of the reaction, the mixture was subjected to solid-liquid separation at the same temperature, and then washed twice with 90 L of toluene at the same temperature. Next, the slurry concentration was set to 0.4 kg /
After adjusting to L, 8.9 mol of butyl ether and 137 mol of titanium tetrachloride were added, and the mixture was reacted at 105 ° C. for 1 hour. After the completion of the reaction, solid-liquid separation was performed at the same temperature, and the solid was washed three times with 90 L of toluene at the same temperature.
After washing three times with 0 L, the solid catalyst component was dried under reduced pressure.
4 kg were obtained. The solid catalyst component contains 1.8% by weight of titanium atom, 20.1% by weight of magnesium atom, 8.4% by weight of phthalic acid ester, 0.3% by weight of ethoxy group and 0.2% by weight of butoxy group. And good particle properties.

[Preparation of polymer] <Pre-activation of solid catalyst component>
Dehydrated and degassed 1.5 L n-hexane, triethylaluminum sufficiently in an autoclave equipped with a stirrer.
5 mmol, 37.5 mmol of t-butyl-n-propyldimethoxysilane and 15 g of the above solid catalyst component were added, and propylene 15
g was continuously supplied over about 30 minutes to perform pre-activation, and then the obtained solid catalyst slurry was transferred to a SUS autoclave with an internal volume of 150 L with a stirrer, and 100 L of liquid butane was added and stored. .

<Polymerization> Two fluidized bed reactors made of SUS and having an internal volume of 1 m ³ and equipped with a stirrer were connected in two tanks, and the first tank (A)
The copolymerization of propylene and ethylene of the component (Component) and the copolymerization of propylene and ethylene of the latter part (Component B) were continuously carried out in the second tank. The analysis result of the obtained propylene-based block copolymer powder shows that [η] _A = 3.5 dl / g,
[Η] _B = 3.8 dl / g, ethylene content in component A 4.0 wt%, ethylene content in component B 13 wt%, B
Component content 45 wt%, CXS content 24 wt%, CXI
The Tm of the S part was 137 ° C. 0.05 parts by weight of calcium stearate based on 100 parts by weight of the obtained propylene-based block copolymer powder, trade name Irganox 10
10 0.2 parts by weight, trade name Irgafos 168
03 parts by weight, melt-extruded with a granulator and adjusted so as to have a melt flow rate (MFR) of 2.1 g / 10 minutes, and a propylene-based block copolymer (PPII-
1) was obtained. Production of Propylene-Butene-1 Copolymer <Polymerization> Two SUS fluidized bed reactors having an internal volume of 1 m ^{3 with} a stirrer were connected, and propylene and butene were continuously copolymerized. Calcium stearate was added to 100 parts by weight of the obtained propylene-butene-1 copolymer powder.
05 parts by weight, 0.2 parts by weight of Irganox 1010 (trade name), 0.03 parts by weight of Irgafos 168 (trade name), 0.054 parts by weight of erucamide, 0.19 parts by weight of thyricia 550 (trade name, manufactured by Fuji Silysia). Melt extrusion with a granulator and melt flow rate (MFR) =
It was adjusted to 3.7 g / 10 minutes to obtain a propylene-butene-1 copolymer (PPI-1). 145 melting point
° C. Example 1 A blend of 50% by weight of PPI-1 and 50% by weight of PPII-1 was prepared.
It was melt-extruded at 50 ° C. and cooled by a cooling roll through which cooling water at 30 ° C. was passed to obtain unstretched polypropylene resin films having a thickness of 30 and 60 μ. 3 obtained
0μ film haze, Young's modulus, impact and 6
Table 1 shows the hexane extraction amount of the 0μ film. The obtained 60 μm polypropylene-based resin film was coated with an ester-based adhesive (base agent Takelac A-31 using a desktop test coater manufactured by Yasui Seiki Co., Ltd.) to a concentration of 2 g / m ^2.
0, a curing agent A 15 μm-thick stretched nylon base film (Unitika brand name emblem) coated with Takenate A-3 (Takeda Pharmaceutical Co., Ltd.) was pressed at 40 ° C. and 3 kg / cm ² , and then pressed at 40 ° C. Dry lamination film was obtained by heat aging for 2 days. Heat sealing is performed by overlapping the surfaces of the polypropylene resin films of this film, and FIG. 1 shows a relationship diagram between the heat sealing temperature and the strength of the obtained film.

Example 2 The same procedure as in Example 1 was carried out except that a composition obtained by blending PPI-1, PPII-1 and Tuffmer P0480 (trade name, manufactured by Mitsui Petrochemical) in the ratio shown in Table 1 was used and evaluated.

Example 3 Instead of PPI-1, trade name Sumitomo Noblen FLX34
E-4 (PPI-2, propylene-ethylene copolymer,
Except for using a melting point of 140 ° C.), the procedure was performed and evaluated in the same manner as in Example 1.

Examples 4 to 5 The same procedures as in Example 1 were carried out except that a composition obtained by blending PPI-2, PPII-1 and Mitsui Petrochemical Co., Ltd., trade name Toughmer P0480 in the ratio shown in Table 1 was used. evaluated.

Comparative Example 1 An evaluation was performed in the same manner as in Example 1 except that PPII-1 was not blended.

Comparative Example 2 The procedure of Example 1 was repeated, except that Tuffmer P0480 (trade name, manufactured by Mitsui Petrochemical) was used in place of the propylene copolymer PPII-1 in the ratio shown in Table 1, and evaluated.

Comparative Example 3 The procedure of Example 3 was repeated except that Toffmer P0480 (trade name, manufactured by Mitsui Petrochemical Co., Ltd.) was used in place of the propylene copolymer PPII-1 in the ratio shown in Table 1, and evaluated.

[0037]

[Table 1]

[0038]

The packaging film comprising the polypropylene resin composition of the present invention is excellent in transparency, low-temperature impact strength, low-temperature heat sealability, heat seal strength, and food hygiene.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between the heat sealing temperature and the strength of the obtained films by performing heat sealing by overlapping the surfaces of the polypropylene resin films in each of the examples and comparative examples.

Claims (4)

[Claims] 1. A copolymer (I) of crystalline propylene with ethylene and / or an α-olefin having 4 or more carbon atoms.
A copolymer component (A component) composed of 40 to 95% by weight, at least a repeating unit derived from propylene, a repeating unit derived from ethylene and / or a repeating unit derived from butene-1, and A propylene-based block copolymer comprising a copolymer component (component B) having a repeating unit derived from ethylene and / or a repeating unit derived from ethylene and / or a repeating unit derived from butene-1 and having a structure different from that of component A. (CXIS) containing 5% by weight or more of a 20 ° C. xylene-soluble part (CXS part) and excluding the CXS part
(B) a propylene-based block copolymer (II) having a maximum melting peak temperature (Tm) of 130 to 155 ° C. measured by a differential scanning calorimeter of 5 to 60% by weight. 2. A propylene-based block copolymer (II)
In the first step, the content of the repeating unit derived from ethylene in the first step is 1.5 to 6.0% by weight, and the total amount of the propylene-ethylene copolymer portion (A component) (A component and the following B component) (Total) of 40 to 85% by weight, and then the content of the repeating unit derived from ethylene in the second step is 7%.
To 17% by weight of a propylene-ethylene copolymer portion (B
Component) in the total polymerization amount (total of component A and component B) 15 to 6
A block copolymer obtained by producing 0% by weight, and the intrinsic viscosity ([η] _B ) of the component _B is 2 to 5 dl /
g, the ratio ([η] _B / [η] _A ) of the intrinsic viscosity of component _B ([η] _B ) to the intrinsic viscosity of component _A ([η] _A ) is 0.5 to
2. A propylene-based block copolymer of 1.8.
The polypropylene-based resin composition according to the above. 3. A packaging film comprising the polypropylene resin composition according to claim 1 or 2. 4. A food packaging film comprising the polypropylene resin composition according to claim 1 or 2.