JP2000119480A - Polypropylene resin composition and its film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polypropylene resin composition having a good balance among main physical properties, including low-temperature impact strength, heat seal strength, clarity, resistance to flex whitening, and heat resistance, by compounding a specific propylene-ethylene block copolymer and a specific ethylene-α-olefin rubber, each having specified MFR and intrinsic viscosity, in a specified wt. ratio. SOLUTION: This composition comprises 90-99 wt.% propylene-ethylene block copolymer and 1-10 wt.% ethylene-α-olefin rubber. The propylene-ethylene copolymer has an MFR of 0.5-20, a content of p-xylene isolubles (after the copolymer is dissolved in boiling p-xylene and is allowed to cool to 25 deg.C) of 60-90 wt.%, a content of p-xylene solubles of 10-40 wt.%, an intrinsic viscosity [η]H of p-xylene insolubles of 1.5-2.8, an intrinsic viscosity [η]EP of p-xylene solubles of 1.5-2.8, a relation represented by the formula: [η]EP<=[η]H+0.5, and an ethylene content of p-xylene solubles of 10-50 wt.%. the ethylene-α-olefin rubber has an MFR of 0.5-20, an intrinsic viscosity [η]EPR of 2.8 or lower, a relation represented by the formula: [η]EPR<=[η]H+0.5, and an ethylene content of 30-90 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polypropylene resin composition and a film thereof. Specifically, it comprises a propylene-ethylene block copolymer and an ethylene-α-olefin copolymer rubber, and has a low-temperature impact resistance,
The present invention relates to a resin composition excellent in film characteristics such as heat seal strength, transparency, bending whitening resistance, heat resistance and the like, and a retort food packaging film molded using the same.

[0002]

2. Description of the Related Art Retort food packaging films include:
Usually, a laminated film is used, and its typical specifications are PET (outside) / aluminum foil (middle) / cast PP (inside), PET / NY / aluminum foil / cast PP, PET / aluminum foil / NY / cast PP, NY /
Cast PP and the like. Cast PP constituting the innermost surface
Is a cast molded film, which comes into contact with food and undergoes a process of pressurizing and sterilizing at 120-135 ° C in a retort pot, so that the film physical properties such as food hygiene, seal strength, heat resistance, impact resistance, etc. Is required.

[0003] Many resins have been proposed as resins suitable for cast PP used as the retort food packaging film. For example, JP-A-6-9306
In Japanese Patent Publication No. 2 (1994), an ethylene-propylene copolymerized part and a propylene homopolymerized part are present at a constant ratio, and the ratio of the former intrinsic viscosity to the latter intrinsic viscosity is not more than a specific value. Have been proposed.

[0004] However, the propylene-ethylene block copolymer is well balanced as a whole in film physical properties, and is particularly excellent in impact resistance at low temperatures. However, whitening of folds and generation of pinholes therefrom are also observed. It is not yet sufficient, such as restrictions on use due to concerns and poor transparency.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a propylene resin composition which balances the main physical properties such as impact resistance at low temperature, heat seal strength, transparency, flex whitening resistance, heat resistance and the like, and using the same. It is an object of the present invention to provide a molded retort food packaging film.

[0006]

Means for Solving the Problems As a result of diligent studies on the above problems, the present inventors have completed the present invention described below. [1] (A) 90 to 99% by weight of a propylene-ethylene block copolymer having the following properties (a1) to (a3);
(B) ethylene-α having the following properties (b1) and (b2)
A polypropylene resin composition comprising 1 to 10% by weight of an olefin copolymer rubber. (A1) Melt flow rate (MFR) is 0.5 to 20 g
/ 10 minutes, (a2) after dissolving in boiling para-xylene,
After cooling to 5 ° C., the proportion of paraxylene-insoluble
９０90% by weight, the intrinsic viscosity ([η] _H ) of the insoluble portion is 1.5-2.8 dl / g, and (a3) after dissolving in boiling para-xylene and cooling to 25 ° C. The proportion of the paraxylene-soluble portion is 10 to 40% by weight, the intrinsic viscosity ([η] _EP ) of the soluble portion is 1.5 to 2.8 dl / g, and [η] _EP ≦ [η]. _H + 0.5, and the ethylene content of the soluble portion is 10 to 50% by weight. (B1) Melt flow rate (MFR) is 0.5 to 20 g.
/ 10 min, and (b2) intrinsic viscosity ([η] _EPR ) is 2.
8 dl / g or less, and [η] _EPR ≤ [η] _H +0.
And (b3) an ethylene content of 30 to 90% by weight. [2] A retort food packaging film obtained by extrusion-molding the polypropylene resin composition according to [1].

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [Polypropylene resin composition] (A) Propylene-ethylene block copolymer The propylene-ethylene block copolymer used in the present invention is a propylene resin having the following properties (a1) to (a3). It is an ethylene block copolymer. (A1) Melt flow rate (MFR) is 0.5 to 20 g
/ 10 minutes, (a2) after dissolving in boiling para-xylene,
After cooling to 5 ° C., the proportion of paraxylene-insoluble
And the intrinsic viscosity ([η] _H ) of the insoluble portion is 1.5 to 2.8 dl / g.
And (a3) after dissolving in boiling para-xylene, at 25 ° C.
The ratio of the para-xylene soluble part after cooling to 10-4
0% by weight, preferably 10 to 30% by weight, the intrinsic viscosity of the soluble part ([η] _EP ) is 1.5 to 2.8 dl / g, and [η] _EP ≤ [η] _H +0 And the content of ethylene in the soluble portion is 10 to 50% by weight, preferably 15 to 50% by weight.
40% by weight, ie the melt flow rate (MF
If R) is less than 0.5 g / 10 minutes, cast molding is difficult, and if it is more than 20 g / 10 minutes, there is a concern that the impact resistance may decrease, and gels and fish eyes may occur.

[0008] The intrinsic viscosity of the boiling para-xylene insoluble part (
If [η] _H ) is less than 1.5 dl / g, the impact resistance, transparency and bending whitening resistance are insufficient, and if it is more than 2.8 dl / g, cast formability becomes difficult. In addition, the intrinsic viscosity ([η] _EP ) of the boiling para-xylene soluble part is 1.5 d
If it is less than 1 / g, blocking resistance such as stickiness of the film may be deteriorated, and if it is more than 2.8 dl / g, transparency may be deteriorated and gels and fish eyes may be generated. Furthermore, if the intrinsic viscosity ([η] _EP ) of the boiling para-xylene-soluble portion is larger than the intrinsic viscosity [η] _H +0.5 of the insoluble portion, the transparency is deteriorated and insufficient.

Further, if the ethylene content of the boiling para-xylene soluble part is less than 10% by weight, the impact resistance is insufficient, and if it is more than 50% by weight, the transparency deteriorates and the bending whitening resistance is insufficient. Becomes The ratio of the boiling para-xylene insoluble part and the boiling para-xylene soluble part is 60% by weight in the former.
If it is smaller, blocking resistance, heat resistance, rigidity, transparency, and bending whitening resistance are reduced, and if the former is more than 90% by weight, impact resistance is insufficient.

[0010] The propylene-ethylene block copolymer used in the present invention can be produced by a usual method. That is, for example, a raw material propylene gas is fed into a first-stage reactor together with a Ziegler-based solid catalyst and a molecular weight regulator hydrogen gas, and the reaction proceeds in a gas phase. The preparation hydrogen gas can be produced by additionally charging the second stage reactor.

(B) Ethylene-α-olefin copolymer The ethylene-α-olefin copolymer used in the present invention is an ethylene-α-olefin copolymer having the following properties (b1) to (b3). (B1) Melt flow rate (MFR) is 0.5 to 20 g
/ 10 min, preferably 1 to 5 g / 10 min, and (b2) an intrinsic viscosity ([η] _EPR ) of 2.8 dl / g or less,
It is preferably 2.0 dl / g or less, and [η] _EPR
.Ltoreq. [. Eta.] _H + 0.5 and (b3) an ethylene content of 30 to 90% by weight, preferably 50 to 85% by weight, that is, a low-crystalline rubbery component, A random copolymer of ethylene and an α-olefin as a comonomer, which can be typically produced by a Ziegler catalyst, but is not limited thereto, and may be a metallocene catalyst. Note that α-
As the olefin, those having 3 to 10 carbon atoms can be used, and specific examples thereof include an ethylene-propylene copolymer, an ethylene-butene-1 copolymer, and an ethylene-octene-1 copolymer. Can use ethylene-propylene rubber (EPR) and ethylene-butene rubber.

The melt flow rate (MFR) is 0.5 g
If it is less than / 10 minutes, the dispersion in polypropylene is poor, and the transparency and flex whitening property are deteriorated. If it is more than 20 g / 10 minutes, the impact resistance is insufficient. In addition, the intrinsic viscosity (
If [η] _EPR ) is greater than 2.8 dl / g, transparency and flex whitening deteriorate, and if the intrinsic viscosity of the boiling para-xylene-insoluble portion of component (A) is greater than [η] _H +0.5, impact resistance is obtained. Run out. Further, if the ethylene content is less than 30% by weight, the resin becomes a crystalline resin, and the impact resistance is reduced.
If the content is more than 10% by weight, the impact resistance is reduced, resulting in poor appearance.

The method for producing the ethylene-α-olefin copolymer used in the present invention is not particularly limited. The method may be a continuous method or a batch method, and may be a solution method, a slurry method, a gas phase method, or a combination thereof. Although the catalyst system is not particularly limited, it is preferable that ethylene and α-olefin are uniformly copolymerized. If the copolymerization is not uniform, a copolymer having a high ethylene concentration and a copolymer having a low ethylene concentration will be mixed, and the transparency will be reduced. Therefore,
It is preferable to use a homogeneous catalyst such as a vanadium catalyst or a metallocene catalyst.

The metallocene catalyst generally reacts with a transition metal compound belonging to Group 4 of the periodic table having a cyclopentadienyl ring and methylaluminoxane or a transition metal compound belonging to Group 4 of the periodic table. This refers to a catalyst comprising a compound that forms an ionic complex and an organoaluminum compound. Further, regarding the polymerization conditions, the polymerization temperature is usually in the range of -50 to 250 ° C, preferably 0 to 200 ° C, the polymerization time is usually in the range of 1 minute to 10 hours, and the pressure is usually Pressure to 300 kg / cm ² -G.

[Blending] 90-99% by weight of (A) the propylene-ethylene block copolymer and (B) 1-10% by weight of the ethylene-α-olefin copolymer are blended to produce a polypropylene resin composition. I do. If the content of the propylene-ethylene block copolymer (A) is less than 90% by weight, the heat sealing strength is reduced, and if it is more than 99% by weight, the impact resistance is reduced. The blending of each component necessary to obtain the resin composition of the present invention is performed by blending various fillers, additives, and the like within a range that does not impair the physical property balance effect of the resin composition of the present invention in addition to the components described above. Or a method in which they are simultaneously mixed in a kneader, or a method in which a part is mixed in advance and then the remaining components are added and kneaded. Specifically, after each component is dry-blended using a Henschel mixer, the mixture is kneaded by setting the cylinder temperature to 200 ° C to 280 ° C with a twin-screw extruder,
Produce pellets. The additives include phenol-based antioxidants, phosphorus-based antioxidants, ultraviolet absorbers, lubricants such as fatty acid amides, and antistatic agents.

[Retort Food Film] The polypropylene resin composition described above has an impact resistance at a low temperature,
The main properties of the film, such as heat seal strength, transparency, bending whitening resistance, heat resistance, etc., are balanced, and it is formed into a film by melt extrusion. In particular, a T-die cast molding method capable of high-speed molding with a large-sized film molding machine is preferable. The film thus obtained is suitable as a retort sealant film, and the thickness thereof is preferably 30 μm or more in order to maintain impact resistance, and is usually used at about 30 to 200 μm.

[0017]

[Resin properties]

(1) Measurement of melt flow index (MFR) According to JIS K7210, temperature 230 ° C, load 21
This is a value measured under the condition of 60 g. (2) Boiling para-xylene dissolution test The proportion of the para-xylene-insoluble portion was determined by adding 5 g of a sample to 700 ml of para-xylene and 2,6-di-tert-butyl-4-methylphenol (BHT) as an antioxidant.
1 g was added, and the mixture was stirred and heated to a boiling temperature to be completely dissolved. After completely dissolved, the mixture was allowed to cool to 25 ° C. for 8 hours or more while stirring, and the precipitated component was collected by filtration with a filter paper. The ratio of the para-xylene soluble part, which was the value determined as the insoluble part, was a value obtained by removing the value of the insoluble part from the total amount of the sample.

(3) Measurement of Intrinsic Viscosity [η] The intrinsic viscosity [η] of the paraxylene-insoluble portion is measured by thoroughly drying the powder collected in the measurement of the amount of insoluble portion.
The intrinsic viscosity [η] is measured at 135 ° C. in decalin. The intrinsic viscosity [η] of the soluble portion is a value measured by the following method. That is, in 700 ml of paraxylene, 5 g of a sample and 2,6-di-
tert-butyl-4-methylphenol (BHT) 1
g was added thereto, and the mixture was stirred while heating to elevate the temperature to the boiling temperature. After completely dissolving the mixture, the mixture was allowed to cool to 25 ° C. for 8 hours or more while stirring, and the precipitated component was filtered off with a filter paper. The obtained filtrate is poured into a large excess of methanol to cause precipitation, which is separated by filtration with a filter paper to obtain a para-xylene-soluble portion. Next, after thoroughly drying, the intrinsic viscosity [η] is measured at 135 ° C. in decalin.

(4) Measurement of the ethylene content in the copolymer The ethylene content in the propylene-ethylene random copolymer and the propylene-ethylene block copolymer was ¹³
It performed by the measurement of a C-NMR spectrum. The measurement was performed under the following measurement conditions using a JNM-EX400 type NMR apparatus manufactured by JEOL Ltd. (NMR measurement conditions) Sample concentration: 220 mg / 3 ml of NMR solvent NMR solvent: 90/10 (volume ratio) of 1,2,4-trichlorobenzene / benzene-d6 Measurement temperature: 130 ° C. Pulse width: 45 ° Pulse repetition time: 4 seconds Integration frequency: 4000 times (measurement) Content of ethylene unit in copolymer (γ (wt
%)) Was calculated from each signal intensity of the ¹³ C-NMR spectrum according to the following equation. The assignment of each signal is shown in Table 1.

Γ = 2X / (300−X) X = Et / S × 100 Et = IEEE + 2/3 (IPEE + IEPE) +1/3 (IPPE + IPEP) S = IEPE + IPPE + IEEE + IPPP + IPEE + IPEP IEPE = I (4) IPPP = I (8) IPPE = I (5) IPEE = I (9) IEEE = I (7) / 2 + I (6) / 4 IPEP = I (10) I (1) is the signal intensity of signal number 1 in Table 1.

[0021]

[Table 1]

[Characteristics of the film] The characteristics of the film, except for the impact resistance, were measured at a temperature of 23 ± 2 ° C. and a humidity of 50 ± 10 ° C.
After conditioning for 16 hours or more at%, measurement was performed under the same temperature and humidity conditions. (1) Impact resistance (film impact) After conditioning the sample at a predetermined temperature ± 2 ° C and a humidity of 50 ± 10% for 16 hours or more, under the same temperature and humidity conditions,
In a film impact tester manufactured by Toyo Seiki Seisaku-sho, evaluation was made by impact breaking strength using a 1/2 inch impact head. (2) Transparency (haze value) Measured according to JIS K7105. (3) Tensile modulus According to JIS K7127, a tensile tester was used to measure crosshead speed: 500 mm / min, measurement direction: machine direction (MD direction), and load cell: 10 kg. (4) Bending whitening resistance The film was bent and visually confirmed. (5) Heat seal strength of retort-treated product Example 1 will be described in detail. (6) Falling bag breaking strength of retort-treated product Example 1 will be described in detail.

Example 1 Production of Polypropylene Resin Composition (Production of Propylene-Ethylene Block Copolymer) (1) Preparation of Magnesium Compound A 500-liter internal reaction vessel equipped with a stirrer was sufficiently replaced with nitrogen gas. 97.2 kg of ethanol and 640 g of iodine
And 6.4 kg of metallic magnesium, and the mixture was reacted with stirring under reflux conditions until hydrogen gas was no longer generated from the inside of the system to obtain a physical reaction product. The reaction liquid containing the solid reaction product was dried under reduced pressure to obtain a target magnesium compound (solid product). (2) Preparation of solid catalyst component 30 kg of the magnesium compound (not pulverized) obtained in the above (1) and purified heptane 1 were placed in a 500-liter reaction vessel equipped with a stirrer sufficiently purged with nitrogen gas.
50 liters, 4.5 liters of silicon tetrachloride and 4.3 liters of diethyl phthalate were charged. While maintaining the inside of the system at 90 ° C., 144 liters of titanium tetrachloride were added with stirring and reacted at 110 ° C. for 2 hours. Then, solid components were separated and washed with purified heptane at 80 ° C. Furthermore, after adding 228 liters of titanium tetrachloride and reacting at 110 ° C. for 2 hours, it was sufficiently washed with purified heptane to obtain a solid catalyst component. (3) Polymerization pretreatment 230 liters of purified heptane was charged into a 500-liter reactor equipped with a stirrer, 25 kg of the solid catalyst component obtained in (2) was added, and then Ti in the solid catalyst component was added. After adding 0.6 mol of triethylaluminum and 0.4 mol of cyclohexylmethyldimethoxysilane to 1 mol of atom, propylene was introduced until the propylene partial pressure became 0.3 kg / cm ² G, and
The reaction was performed at 5 ° C. for 4 hours. After completion of the reaction, the solid catalyst component was washed several times with purified heptane, carbon dioxide was supplied, and the mixture was stirred for 24 hours.

(4) Polymerization As a pre-stage, the treated solid catalyst component of (3) was placed in a 200-liter polymerization apparatus (R-1) with a stirrer at a concentration of 3 mmol / hr in terms of Ti atoms, and triethylaluminum was added. 413 mmol / hr (7.5 mmol / kg-
PP), cyclohexylmethyldimethoxysilane
At a polymerization temperature of 75 ° C. and a total pressure of 30 kg / cm ^{2 at a} rate of 0.05 mmol / hr (1.9 mmol / kg-PP).
G polymerized propylene. At this time, the supply amounts of propylene and hydrogen were adjusted so that the gas compositions shown in Table 2 were obtained. Next, the powder was continuously withdrawn from R-1 and a polymerization device (R-
Transferred to 2). In the case of R-2, the polymerization temperature is 50 ° C. and the total pressure is 11
Propylene and ethylene were copolymerized at kg / cm 2 G. At this time, the supply amounts of propylene, ethylene and hydrogen were adjusted so that the gas compositions shown in Table 2 were obtained. Table 3 shows the properties of the polymer thus obtained.

(Rubber-like polymer) As a rubber-like polymer, an ethylene-propylene copolymer (EP-913 manufactured by JSR Corporation) is used.
Y) was used. The resin has a melt flow rate (MFR) of 3.6 g / 10 minutes, an intrinsic viscosity [η] of 1.4 dl / g, and an ethylene content of 76% by weight.

(Blending) 95 kg of the above propylene-ethylene block copolymer was mixed with an antioxidant Irganox 10
10 at 700 ppm, Irgafos 168 at 250 pp
m, 500 ppm of neutralizing agent calcium stearate, D
HT-4A was compounded at 500 ppm, and kneaded and granulated with a TEM (biaxial kneader). Ethylene-propylene copolymer rubber (EP-913Y manufactured by JSR) was added to 9.5 kg of the obtained propylene-ethylene block copolymer pellets in an amount of 0.1 kg.
5 kg was dry-blended with a tumbler blender and then applied to a cast molding machine.

[Preparation of Film by Casting] A single screw extruder having a screw diameter of 40 mm has a die width of 50 mm.
Using a cast molding machine equipped with a 0 mm coat hanger type T die, a film having a thickness of 60 μm was formed at a die exit temperature of 250 ° C., a screw rotation speed of 80 rpm, a chill roll temperature of 30 ° C., and a take-up speed of 7.5 m / min. The film was subjected to corona treatment (processing density 80 W
/ M ² / min). The film properties (film impact strength, haze, and flex whitening resistance) of the obtained film were evaluated, and the results are shown in Table 4.

Next, the film is PET-coated from the outside.
(12 μm) / Aluminum foil (7 μm) / Film (6
0 μm) and dry-laminated via an adhesive. The adhesive used was Takeda Pharmaceutical A-536 / A-5.
Using 0 (base / curing agent), aging was performed at 40 ° C./5 days for the effect of the adhesive after lamination. Laminate film is made under the following conditions,
A flat bag having a size of 150 mm was prepared. The sealing temperature was 200 ° C./210° C. (twice sealing) for the side seal and 190 ° C. for the bottom seal. Seal pressure is 3.0k
At g / cm ² , the sealing time was 0.7 seconds. The bag making speed was 36 bags / min.

This bag is filled with 120 cc of water, and the upper end of the bag is heat-sealed with an impulse sealer.
The retort treatment was performed at 2.0 atm for 30 minutes. As the practical strength of the package of the obtained retort-treated product, the heat sealing strength and the falling bag breaking strength were measured, and the results are shown in Table 4. As for the heat seal strength, the side seal portion of the formed bag was subjected to a crosshead speed of 30 with a tensile tester.
The peel strength is measured under the conditions of 0 mm / min and a load cell of 10 kg. Further, for the drop bag breaking strength, after the sample after the retort treatment was conditioned at 0 ° C. for 24 hours, the bags containing the same samples were stacked to form a two-stage stack, and the bag to be tested was placed 1.0 m below. Was dropped horizontally on the metal floor from the height of the bag, and the average number of times until the bag was broken (average of 15 tests) was determined.

Example 2 In Example 1, ethylene-
It carried out similarly except having changed the propylene copolymer (EP-913Y by JSR) from 0.5 kg to 0.2 kg. The properties of the obtained polymer are shown in Table 3, and the physical properties of the obtained film and the strength of the retorted product were measured.

Example 3 In the production of the propylene-ethylene block copolymer in Example 1, the gas composition such as the raw material gas used as shown in Table 2 was changed in the reactor (R-1) in the preceding stage. The hydrogen gas was changed from 0.07 mol% to 0.1 mol%, the propylene gas was changed from 81.4 mol% to 78.0 mol%, and the ethylene gas was changed to 14.7 mol% in the reactor (R-2) in the latter stage. To 17.1 mol% of hydrogen gas.
The same procedure was followed except that the amount was changed from 1 mol% to 4.9 mol%. Further, when compounding the resin composition, the ethylene-propylene copolymer (EP-913Y manufactured by JSR) was added for 5k.
The same operation was carried out except that g was changed to 9 kg. The properties of the obtained polymer are shown in Table 3, and the physical properties of the obtained film and the strength of the retorted product were measured.

Comparative Example 1 A film was formed using only the propylene-ethylene block copolymer in Example 1, and the physical properties of the obtained film and the strength of the retorted product were measured. [Comparative Example 2] The gas composition of the raw material gas and the like used in the production of the propylene-ethylene block copolymer in Example 1 was changed to 0.07 hydrogen gas in the reactor (R-1) in the preceding stage.
Propylene gas from 81.4 mol% to 78.0 mol% in the reactor (R-2) in the latter stage.
And ethylene gas from 14.7 mol% to 17.1 mol%
In the same manner, except that the hydrogen gas was changed from 4.1 mol% to 4.9 mol%. Table 3 shows the properties of the obtained polymer.
In addition, a film was formed using only the propylene-ethylene block copolymer, and the physical properties of the obtained film and the strength of the retorted product were measured.
It is shown in Table 4.

Comparative Example 3 In the production of the propylene-ethylene block copolymer in Example 1, the gas composition of the raw material gas and the like was changed to 0.07 in the reactor (R-1) in the preceding stage. Mol% to 0.15 mol%, propylene gas in the latter reactor (R-2) from 81.4 mol% to 81.0 mol%, and ethylene gas from 14.5 mol% to 15.1 mol%. And hydrogen gas from 4.1 mol% to 3.
Except having changed to 9 mol%, it manufactured similarly. The properties of the obtained polymer are shown in Table 3, and further, a film was formed using only the propylene-ethylene block copolymer, and the physical properties of the obtained film and the strength of the retorted product were measured. It is shown in Table 4. [Comparative Example 4] In Example 1, IDEMITSU PP (F-454NP) was used as a propylene-ethylene block copolymer,
Further, a film was formed using only the propylene-ethylene block copolymer, and the physical properties of the obtained film and the strength of the retorted product were measured.

[Comparative Example 5] In producing a propylene-ethylene block copolymer in Example 1, the gas composition of the raw material gas and the like used was changed to 0.07 hydrogen gas in the reactor (R-1) in the preceding stage. Mol% to 0.15 mol%, propylene gas in the latter reactor (R-2) from 81.4 mol% to 81.0 mol%, and ethylene gas from 14.5 mol% to 15.1 mol%. And hydrogen gas from 4.1 mol% to 3.
Except having changed to 9 mol%, it manufactured similarly. Furthermore, when compounding the resin composition, 5 kg to 15 kg of ethylene-propylene copolymer (EP-913Y manufactured by JSR)
Was carried out in the same manner, except that The properties of the obtained polymer are shown in Table 3, and the physical properties of the obtained film and the strength of the retorted product were measured. [Comparative Example 6] In Example 1, IDEMITSU PP (F-454NP) was used as a propylene-ethylene block copolymer,
Further, the resin composition was blended in the same manner as in Example 1, and the properties of the obtained polymer are shown in Table 3. The physical properties of the obtained film and the strength of the retorted product were measured.

[0035]

[Table 2]

[0036]

[Table 3]

[0037]

[Table 4]

[0038]

According to the present invention, the film properties such as low-temperature impact resistance, heat seal strength, transparency, bending whitening resistance, heat resistance, etc. are balanced, and a laminate using the cast film of the present invention. It has excellent performance in practical strength of retort-treated products packaged with film.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 23:08) B29K 23:00

Claims (2)

[Claims] 1. A propylene-ethylene block copolymer having the following properties (a1) to (a3): 90 to 99% by weight, and (B) ethylene having the following properties (b1) to (b3):
A polypropylene resin composition comprising 1 to 10% by weight of an α-olefin copolymer rubber. (A1) Melt flow rate (MFR) is 0.5 to 20 g
/ 10 minutes, (a2) after dissolving in boiling para-xylene,
After cooling to 5 ° C., the proportion of paraxylene-insoluble
９０90% by weight, the intrinsic viscosity ([η] _H ) of the insoluble portion is 1.5-2.8 dl / g, and (a3) after dissolving in boiling para-xylene and cooling to 25 ° C. The proportion of the paraxylene-soluble portion is 10 to 40% by weight, the intrinsic viscosity ([η] _EP ) of the soluble portion is 1.5 to 2.8 dl / g, and [η] _EP ≦ [η]. _H + 0.5, and the ethylene content of the soluble portion is 10 to 50% by weight. (B1) Melt flow rate (MFR) is 0.5 to 20 g.
/ 10 min, and (b2) intrinsic viscosity ([η] _EPR ) is 2.
8 dl / g or less, and [η] _EPR ≤ [η] _H +0.
5, and (b3) the ethylene content is 30 to 90% by weight. 2. A retort food packaging film obtained by extruding the polypropylene resin composition according to claim 1.