JPH07227945A - Polypropylene laminated film - Google Patents

Abstract

PURPOSE:To obtain a polypropylene laminated film excellent in low temp. heat sealability and hot tack properties without damaging transparency and blocking resistance. CONSTITUTION:A polypropylene laminated film is obtained by laminating a propylene/alpha-olefin random copolymer obtained by vapor phase polymerization using a specific catalyst system under such a condition that a liquid medium is substantially absent and satisfying conditions such that alpha-olefin content (1) is 15-30wt.%, a melt flow rate (2) is 20g/10 min or less, a wt. average mol. wt/number average mol. wt ratio (3) is 4.5 or less, a relational expression (4) of alpha-olefin content (A wt.%) and the cold xylene soluble part of the copolymer (B wt.%) is B <=1.05A-10 and the alpha-olefin content (5) of the cold xylene soluble part is below 1.7 times the alpha-olefin content of the copolymer on at least the single surface of a crystalline polypropylene layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polypropylene laminated film which is excellent in low-temperature heat sealability and hot tackiness without impairing transparency and blocking resistance.

[0002]

2. Description of the Related Art A crystalline polypropylene biaxially stretched film (referred to as BOPP) is widely used as a packaging film because of its excellent rigidity, transparency and moisture resistance. However, since BOPP has a problem in heat sealability, it has hitherto been widely used as a laminated film obtained by laminating or coextruding a resin excellent in heat sealability on one side or both sides thereof. As a property required for this heat seal resin, it has hitherto been considered that how low the heat seal temperature can be lowered, that is, low temperature heat sealability is the most important. This is because the lower the heat-sealing temperature, the higher the bag-making speed of the laminated film and the higher the productivity. Needless to say, properties such as transparency and blocking resistance are also important. However, in recent years, the diversification of packaging forms, that is, the diversification of items to be packaged and the diversification of packaging machines accompanying it, have been rapidly progressing, and low-temperature heat-sealing has also been considered not so important in the conventional BOPP. Like sex, it has come to be regarded as important.

Various proposals have hitherto been made as a heat-sealing resin for BOPP. That is, as a propylene-based heat-sealing resin, a propylene-ethylene copolymer obtained by copolymerizing about 5% by weight of ethylene is well known, and is excellent in transparency, blocking resistance, etc., but low-temperature heat-sealing property is extremely insufficient. It was a thing. When the ethylene content of the copolymer is increased to improve the low temperature heat-sealing property of the propylene-ethylene copolymer, the low temperature heat-sealing property is improved to some extent, but the transparency and the blocking resistance are extremely deteriorated. There was a problem of becoming. Propylene-butene-1 copolymers obtained by copolymerizing butene-1 with propylene are also well known, and are disclosed in, for example, JP-A-50-128781 and JP-A-55-1.
Japanese Patent No. 7542 discloses a propylene-butene-1 copolymer which is polymerized in an inert solvent (so-called slurry polymerization) and in which components soluble in the inert solvent are removed, and the transparency and resistance to The blocking property is good, and the low-temperature heat-sealing property also shows a very good result. Further, JP-A-56-22307 discloses a propylene-butene-1 copolymer having a specific sequence distribution, which is polymerized by using a solid compound based on titanium trichloride and an organometallic compound as a catalyst system in the absence of a liquid diluent. Although a polymer is shown, there are problems that the low temperature heat sealability is insufficient, the blocking resistance is poor, and the transparency deteriorates with time. Further, JP-A-60-16645 discloses a propylene-butene-1 copolymer obtained in the gas phase in the substantial absence of a liquid medium, which shows low-temperature heat-sealing property, transparency and resistance to heat. Although the blocking properties are good, the hot tack property is insufficient in our additional test. Further, a propylene-ethylene-butene-1 terpolymer obtained by copolymerizing propylene with ethylene and butene-1 is also well known as a heat seal resin. For example, in JP-A-54-26891, ethylene is added to propylene in an amount of 0.1 to 4% by weight and an α having 4 to 8 carbon atoms.
-A method for producing an olefin copolymer in which olefin is supplied to a polymerization system in a ratio of 1 to 30% by weight is described. Further, in JP-A-53-26882, ethylene is 0.5 to
A propylene terpolymer characterized by a substantially statistical comonomer distribution of 1.9% by weight and butene-1 of 0.5 to 4.9% by weight and a process for its preparation are described. Further, in JP-A-55-115416, low crystallinity is obtained by copolymerizing 0.2 to 9 mol% of ethylene and 0.2 to 9 mol% of linear α-olefin having 4 or more carbon atoms with propylene. It is described that a soft or semi-rigid copolymer can be obtained. However, none of them satisfies the low-temperature heat-sealing property and the hot-tack property at the same time, and does not show excellent transparency and blocking resistance.

[0004]

An object of the present invention is to provide a polypropylene laminated film having both excellent low temperature heat sealability and hot tack property without impairing good transparency and blocking resistance. is there.

[0005]

Means for Solving the Problems As a result of intensive studies in view of the above problems, the present inventors have found that a specific catalyst system, a specific comonomer composition obtained by a polymerization method, a molecular weight distribution and a specific cold xylene-soluble portion and It was found that a polypropylene laminated film obtained by laminating a random copolymer of propylene having a cold xylene-soluble part composition and an α-olefin having 4 or more carbon atoms as a heat-sealing resin also has the above-mentioned various characteristics. completed.

That is, the present invention uses a catalyst system comprising a solid catalyst component containing magnesium, titanium and halogen as essential components, an organoaluminum compound and an electron donating compound on at least one surface of the crystalline polypropylene layer, and substantially A random copolymer of propylene and α-olefin having 4 or more carbon atoms obtained by gas phase polymerization in the absence of a liquid medium, and a copolymer satisfying the following conditions (1) to (5) are laminated. The present invention relates to a polypropylene laminated film. (1) The content of α-olefin having 4 or more carbon atoms in the copolymer is 15 to 30% by weight (2) The melt flow rate of the copolymer is 20 g / 10 minutes or less (3) The weight average molecular weight of the copolymer / Number average molecular weight is 4.
5 or less (4) The relational expression between the α-olefin content of 4 or more carbon atoms (A wt%) of the copolymer and the cold xylene-soluble part (B wt%) of the copolymer is B ≦ 1.05A-10. (5) α having 4 or more carbon atoms in the cold xylene-soluble part of the copolymer
-Olefin content is less than 1.7 times the α-olefin content of 4 or more carbon atoms of the copolymer.

The first feature of the laminated film obtained by the present invention is that both the low temperature heat sealability and the hot tack property are excellent. The second feature is low temperature heat sealability,
In addition to being excellent in hot tack, it is also excellent in transparency and blocking resistance.

The random copolymer of propylene and α-olefin having 4 or more carbon atoms to be used for the heat-sealing resin of the present invention is produced by a so-called vapor phase polymerization method. In the slurry polymerization method which is generally widely used and in which polymerization is carried out in an inert hydrocarbon, a large amount of the polymer is dissolved in the inert hydrocarbon solvent, so that the polymerization becomes extremely difficult and a polymer which meets the object of the present invention can be obtained. In addition to the above, the polymer yield is significantly reduced, which is economically disadvantageous. The polymerization can be carried out by a known fluidized bed reactor, a fluidized bed reactor with a stirrer or the like. Further, the polymerization does not liquefy the gas in the reactor, and the temperature at which the polymer particles do not melt and agglomerate,
It is essential to carry out under pressure conditions, and particularly preferable polymerization conditions include a temperature range of 50 to 95 ° C. and 2
It is a pressure range of up to 30 kg / cm ² (gauge pressure, hereinafter abbreviated as G). Further, for the purpose of controlling the melt fluidity of the obtained polymer, it is preferable to add a molecular weight modifier such as hydrogen. The polymerization can be carried out by any of batchwise polymerization, continuous polymerization or a combination of both methods, and the monomer and the molecular weight modifier consumed in the polymerization are continuously or intermittently. It can be fed to the reactor. The copolymer used in the present invention can be washed with alcohol or a hydrocarbon solvent or the like for the purpose of removing catalyst residues or low molecular weight polymers after the gas phase polymerization.

In the present invention, the catalyst system used for producing the copolymer to be used as the heat-sealing resin is a known catalyst for stereoregular polymerization of α-olefin, and a solid catalyst containing magnesium, titanium and halogen as essential components. A catalyst system comprising a component (A), an organoaluminum compound (B) and an electron donating compound (C).

The solid catalyst component (A) contains titanium, magnesium and halogen as essential components. Generally, a solid product obtained by reducing a titanium compound with an organomagnesium compound is treated with an ester compound and then Obtained by treating with titanium chloride.

Titanium compounds have the general formula Ti (OR) _b X
_4-b (R is a hydrocarbon group having 1 to 20 carbon atoms, X is a halogen atom, and b is a number of 0 <b ≦ 4).
Specific examples of R include methyl, ethyl, propyl, is
o-propyl, butyl, iso-butyl, amyl, is
o-amyl, hexyl, heptyl, octyl, decyl,
Examples thereof include alkyl groups such as dodecyl, aryl groups such as phenyl, cresyl, xylyl, and naphthyl, cycloalkyl groups such as cyclohexyl and cyclopentyl, allyl groups such as propenyl, and aralkyl groups such as benzyl group.

As the magnesium component, any type of organomagnesium compound containing a magnesium-carbon bond can be used. Particularly, a Grignard compound represented by the general formula RMgX (wherein R represents a hydrocarbon group having 1 to 20 carbon atoms, and X represents halogen) and a general formula RR'Mg (wherein R and R'are carbon It represents a hydrocarbon group of the formula 1 to 20. Here, R and R ′ may be the same or different.) A magnesium compound represented by the following is preferably used.

As Grignard compounds, methylmagnesium chloride, ethylmagnesium chloride, ethylmagnesium bromide, ethylmagnesium iodide, propylmagnesium chloride, propylmagnesium bromide, butylmagnesium chloride, butylmagnesium bromide, sec-butylmagnesium chloride, sec-butylmagnesium Bromide, tert
-Butylmagnesium chloride, tert-butylmagnesium bromide, amylmagnesium chloride, is
o-amylmagnesium chloride, phenylmagnesium chloride, phenylmagnesium bromide, etc.
As magnesium compounds represented by R'Mg, diethyl magnesium, dipropyl magnesium, di-iso-
Propyl magnesium, dibutyl magnesium, di-s
ec-Butyl magnesium, di-tert-butyl magnesium, butyl-sec-butyl magnesium, diamyl magnesium, diphenyl magnesium and the like can be mentioned.

The organoaluminum compound (B) used in combination with the solid catalyst component (A) is at least 1 in the molecule.
It has a single A1-carbon bond. Specific examples of such an organoaluminum compound include triethylaluminum, triisobutylaluminum, trialkylaluminum such as trihexylaluminum, diethylaluminum halide, dialkylaluminum halide such as diisobutylaluminum halide, a mixture of trialkylaluminum and dialkylaluminum halide, tetraethyl. Examples include alkylalumoxane such as dialumoxane and tetrabutyl dialumoxane. Among these organoaluminum compounds, trialkylaluminum, a mixture of trialkylaluminum and dialkylaluminum halide, alkylalumoxane is preferable, and triethylaluminum, triisobutylaluminum, a mixture of triethylaluminum and diethylaluminum chloride and tetraethyldialumoxane are particularly preferable. preferable. The amount of the organoaluminum compound used is 1 to 1000 per 1 mol of titanium atom in the solid catalyst.
It can be selected over a wide range such as moles, but especially 5-6
A range of 00 mol is preferred.

The electron-donating compound is represented by the general formula R ₁ R
A silicon compound (C) represented by ₂ Si (OR ₃ ) ₂ is preferably used, and the following are exemplified.

Each catalyst is composed of A1 atom in the component (B) /
The molar ratio of Ti atoms in the component (A) is 1 to 1000, preferably 5 to 600, and the molar ratio of A1 atoms in the component (C) / component (B) is 0.02 to 500, preferably 0.05. ~
The polymerization temperature is 20 to 150 ° C., preferably 50 to 95 ° C., and the polymerization pressure is atmospheric pressure to 40 kg / cm.
Polymerization is carried out in the absence of a solvent of ² G, preferably ^{2 to} 30 kg / cm ² G, by supplying hydrogen for controlling the molecular weight of propylene, α-olefin and the copolymer.

The random copolymer of propylene and α-olefin having 4 or more carbon atoms to be used in the heat-sealing resin of the present invention contains a specific amount of α-olefin having 4 or more carbon atoms.
The content of α-olefin having 4 or more carbon atoms in the copolymer is 1
It is 5 to 30% by weight, preferably 18 to 25% by weight. When the content of the α-olefin having 4 or more carbon atoms in the copolymer is less than 15% by weight, the effect of improving the low temperature heat-sealing property and the hot tack property of the laminated film becomes insufficient, and the carbon number of the copolymer is low. When the content of the α-olefin of 4 or more exceeds 30% by weight, the powder properties are deteriorated during the gas phase polymerization of the copolymer, and stable production becomes difficult.

Melt flow rate (MFR) at 230 ° C. of a random copolymer of propylene and α-olefin having 4 or more carbon atoms, which is used for the heat-sealing resin of the present invention.
Is preferably 20 g / 10 minutes or less, more preferably 3 to 15 g / 10 minutes. MFR is a parameter showing the average molecular weight of the polymer, and a large value thereof means a small average molecular weight. When the MFR of the copolymer exceeds the upper limit, the effect of improving the hot tack property of the laminated film may be insufficient, and the MFR of the copolymer may be insufficient.
If it is extremely small, the effect of improving the low-temperature heat-sealing property of the laminated film may be insufficient, or problems such as poor fluidity may occur during film formation, which is not preferable.

Gel permeation chromatography (GP) of a random copolymer of propylene and an α-olefin having 4 or more carbon atoms, which is used in the heat-sealing resin of the present invention.
C) Weight average molecular weight / number average molecular weight (Mw / M
The value of n) is 4.5 or less, and more preferably 4.0 or less. Mw / Mn is a value indicating the molecular weight distribution of the polymer,
A small value means a narrow molecular weight distribution. It is not clear how the molecular weight distribution of the polymer affects the heat sealing performance such as low temperature heat sealing property and hot tacking property, but the low molecular weight component contained in a large amount in the wide molecular weight distribution product affects the heat sealing performance in some way. It can be expected that it is given.

The cold xylene soluble part (CXS) of the random copolymer of propylene and α-olefin having 4 or more carbon atoms to be used in the heat-sealing resin of the present invention is the α-olefin having 4 or more carbon atoms of the copolymer. It has the following relational expression with the content. B ≦ 1.05A-10 (A: α-olefin content in random copolymer (wt%), B: cold xylene soluble part (CXS) (wt%)) Cold xylene soluble of the copolymer When the content of α-olefin having 4 parts or more and 4 or more carbon atoms does not satisfy the above formula, the effect of improving the hot tack property of the laminated film becomes insufficient, and the blocking resistance, and further the printability depending on the use, may be a problem. In some cases, it is not preferable.

The content of α-olefin having 4 or more carbon atoms in the cold xylene-soluble portion of the random copolymer of propylene and α-olefin having 4 or more carbon atoms used for the heat-sealing resin of the present invention is the same as that of the copolymer. It is less than 1.7 times the content of α-olefin having 4 or more carbon atoms. When the content of α-olefin having 4 or more carbon atoms in the cold xylene-soluble part of the copolymer is 1.7 times or more the content of α-olefin having 4 or more carbon atoms of the copolymer, the laminated film is hot. The effect of improving tackiness may be insufficient, which is not preferable.

In the present invention, the copolymer used for the heat-sealing resin is obtained by gas phase polymerization, but it may be subjected to an appropriate washing step without post-treatment such as washing step.

In the present invention, the copolymer to be used as the heat-sealing resin may be blended with a rubber-like ethylene-α-olefin copolymer, polybutene-1 containing a copolymer type, etc., up to about 20% by weight. Yes, or a small amount of another polymeric material can be blended. Further, additives such as an antistatic agent, an antiblocking agent, a lubricant and a stabilizer can be added.

The polypropylene laminated film of the present invention comprises
It can be obtained by laminating the above heat-sealable resin on one side or both sides of the crystalline polypropylene film as a base material by a known method. That is, a method in which a preformed sheet of a base layer and a heat seal resin layer is passed together between pressure rollers using an adhesive, and the heat seal resin is applied onto the base layer as a solution or dispersion of a solvent such as toluene. Of the heat-sealing resin and the base layer by melt extrusion coating on the base layer, or by extruding the heat-sealing resin and the base polymer with separate extruders in a common die or at the outlet, both of which are still in a molten state. The laminated film of the present invention can be obtained by a method such as joining.

The laminated film of the present invention is preferably uniaxially or biaxially stretched after laminating a heat seal resin.
Such a polypropylene stretched laminated film is manufactured by the following known method. That is, in the extrusion die for forming the sheet, or in the vicinity of the outlet, a raw fabric laminated sheet is produced by so-called co-extrusion that combines the two in a molten state, and then biaxially stretched. A method in which a heat-sealing resin is extrusion laminated on a polypropylene sheet as a base material and then biaxially stretched. There is a method in which a polypropylene sheet as a base material is previously uniaxially stretched in MD with a roll group including a metal roll in a heated state, a heat seal resin is extrusion-laminated on this sheet, and then stretched in TD. The MD stretching temperature of the laminated film is usually 120 to 160 ° C., and the MD stretching ratio is 3 to 8 times. The stretching temperature of TD is 145 to 165 ° C.
The stretching ratio of TD is usually 4 to 10 times. Regarding the thickness of the laminated film, the thickness of the copolymer layer (heat seal resin layer) is usually 0.1 to 10 μm, and the thickness of the base material layer (polypropylene layer) is usually 10 to 100 μm. The polypropylene laminated film produced as described above has both excellent low-temperature heat-sealing property and hot-tack property, and also has good transparency and blocking resistance, and further has good printability and can be produced at a very low cost. It has practical value.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the examples as long as the gist thereof is not exceeded. The measurement of each item in Examples and Comparative Examples was carried out according to the following methods. (1) Content of α-olefin (butene-1) (% by weight) It was determined from the following formula by the IR spectrum method. Butene 1 content (% by weight) = 1.208 K'K '= absorbance at 767 cm ^-1 (2) Weight average molecular weight / number average molecular weight (Mw / Mn) By gel permeation chromatography (GPC) under the following conditions: It was measured. The calibration curve was prepared using standard polystyrene. Model Millipore Waters 150 CV type column Shodex M / S 80 Measurement temperature 145 ° C., solvent orthodichlorobenzene,
Sample concentration 5mg / 8ml Under these conditions, NBS (National Bureau of Standard)
s) Standard Reference Meterial 706 (Mw / M
When a polystyrene of n = 2.1) was measured, a molecular weight distribution (Mw / Mn) of 2.1 was obtained. (3) Melt flow rate (MFR) (g / 10 minutes) It was measured by the method of condition -14 according to JIS K7210. (4) Low-temperature heat-sealing property (heat-sealing temperature) ℃ ^Two films are superposed, and a heat sealer (manufactured by Toyo Seiki) heated to a predetermined temperature is used to load ² kg / cm ² G of load.
Press for seconds and heat seal. After standing overnight, the sealing temperature at which the peeling resistance was 300 g / 25 mm when peeled at a peeling speed of 200 mm / min and a peeling angle of 180 ° at 23 ° C., was determined as the heat-sealing temperature. (5) Hot tack property (g / 3 inch (76.2 mm)) The surfaces of the copolymer layers of the two laminated films are superposed on each other and cut into a width of 3 inches (76.2 mm) and a length of 150 mm. Next, the load spring is bent by hand, and both ends of the copolymer layer surface of the sample are attached to the outside of the load spring. Then, a heat sealer (manufactured by Tester Sangyo Co., Ltd.) preheated to a predetermined temperature is pressure-bonded under a load of 2 kg / cm ² G for 2 seconds to perform heat sealing. The peeling force is applied to the heat-sealed portion by releasing the hand that held the load spring immediately before the heat-seal bar went up. Remove the sample from the load spring and measure the length of the peeled section. By changing the load of the load spring from 53g to 295g, the peeling length of the seal part is 1/8
The spring load indicating inches (3.2 mm) was taken as the hot tack temperature.

[0027]

【Example】

Reference example (a) Synthesis of organomagnesium compound 1 L equipped with stirrer, reflux condenser, dropping funnel, and thermometer
After the flask was replaced with argon, 32.0 g of ground magnesium for Grignard was charged. A dropping funnel was charged with 120 g of butyl chloride and 500 ml of dibutyl ether, and about 30 ml was added dropwise to magnesium in the flask to start the reaction. After the reaction was started, the dropping was continued at 50 ° C. for 4 hours, and after the dropping was completed, the reaction was continued at 60 ° C. for another hour. Then, the reaction solution was cooled to room temperature, and the solid content was filtered off. Butyl magnesium chloride in dibutyl ether was hydrolyzed with 1N sulfuric acid, and the concentration was determined by backtitration with 1N sodium hydroxide aqueous solution using phenolphthalein as an indicator. The concentration was 2.1 mol / L.
Met.

(B) Synthesis of solid product After replacing a 500 ml flask equipped with a stirrer and a dropping funnel with argon, 240 ml of hexane, 5.4 g (15.8 mmol) of tetrabutoxytitanium and 61.4 g of tetraethoxysilane were added. (295 mmol) was added to make a uniform solution. Next, while maintaining the temperature in the flask at 5 ° C., 150 ml of the organomagnesium compound synthesized in (a),
It dripped gradually from the dropping funnel over 4 hours. After completion of dropping, the mixture was stirred at room temperature for 1 hour and then solid-liquid separated at room temperature.
The washing with 240 ml of hexane was repeated 3 times, and the residue was dried under reduced pressure to obtain 45.0 g of a dark brown solid product. The solid product contains 1.7% by weight of titanium atoms and 3% of ethoxy groups.
It contained 3.8% by weight and 2.9% by weight of butoxy group. In addition, no clear diffraction peak was observed in the wide-angle X-ray diffraction pattern of this solid product by Cu-Kα line, and the solid product had an amorphous structure.

(C) Synthesis of ester-treated solid After purging the 100 ml flask with argon, 6.5 g of the solid product synthesized in (b), 16.2 ml of toluene and 4.3 ml (16 mmol) of diisobutyl phthalate were added. ,
The reaction was carried out at 95 ° C for 1 hour. (D) Synthesis of solid catalyst (activation treatment) After completion of washing in (c) above, toluene 16.
2 ml, diisobutyl phthalate 0.36 ml (1.3 mmo
l), 2.2 ml (13 mmol) of butyl ether and 38.0 ml (346 mmol) of titanium tetrachloride were added, and the mixture was mixed at 95 ° C. for 3 days.
The reaction was carried out over time. After completion of the reaction, solid-liquid separation was carried out at 95 ° C., and then washing with 33 ml of toluene was conducted twice at the same temperature. The above treatment with the mixture of diisobutyl phthalate, butyl ether and titanium tetrachloride was repeated once more under the same conditions, and the mixture was washed with 33 ml of hexane three times to obtain 5.0 g of an ocher solid catalyst. The solid catalyst contained 2.1% by weight of titanium atoms, 19.9% by weight of magnesium atoms, and 12.7% by weight of phthalic acid ester.

Example 1 (a) Catalyst component 150 L of sufficiently purified hexane was added to a 250 L reactor equipped with a stirrer, the system was sufficiently nitrogen-substituted, and then 3.2 mol of triethylaluminum (hereinafter abbreviated as TEA) was added.
Cyclohexylethyldimethoxysilane (hereinafter CCHE
(Abbreviated as MS) 0.32 mol and 51.8 g of the solid catalyst obtained in the above Reference Example in terms of Ti atoms are added. While maintaining 25 ° C, 2.8 kg of propylene was continuously added over 2 hours.

(B) Polymerization Using a polymerization tank with an internal volume of 1000 L, the polymerization temperature is 65 ° C.
Combined pressure 12.5kg / cm ² Average residence time of 6 hours
Is supplied with the catalyst component prepared in (a), and at the same time TEA3
9 mmol / hr and CHEDMS 2.8 mmol / hr are supplied.
H in the polymerization tank₂ The concentration is 0.21vol.% And butene
-1 Propylene and butene so that the concentration becomes 22 vol.%
-1 was continuously supplied to carry out gas phase polymerization. Obtained co
The butene-1 content of the polymer was 21.7% by weight.
(Table 1). 100 parts by weight of this copolymer was added to stearic acid
Lucium 0.15 parts by weight, Sumilizer BHT 0.1
Add 0.05 parts by weight of Irganox 1010
After mixing with a Henschel mixer, melt extrusion is performed
Let it.

(C) Laminating and Stretching The resulting copolymer pellets are pressed to 100%.
500 μ homopolypropylene sheet (MFR = 2.
5) and fusion pressing were performed by a pressing method to obtain a laminated sheet. Next, a 90 mm × 90 mm sample was taken from the obtained laminated sheet to obtain a biaxially stretched film under the following conditions. Stretching machine: tabletop biaxial stretching machine manufactured by Toyo Seiki Temperature: 150 ° C. Preheating time: 3 minutes Stretching ratio: 5 × 5 times Stretching speed: 5 m / min The physical properties of the 24 μ laminated stretched film obtained above are shown in Table 2.
Shown in. This laminated stretched film has a low temperature heat sealability,
The hot tack property was excellent.

Example 2 A copolymer was obtained under the same polymerization conditions as in Example 1 except that the H ₂ concentration in the polymerization tank was changed to 1.1 vol.%. The copolymer obtained had an MFR of 14 g / 10 min and a butene-1 content of 2
It was 1.8% by weight. (Table 1) Table 2 shows the physical properties of the laminated stretched film that was pelletized under the same conditions as in Example 1, laminated and stretched.
Shown in. All of them showed excellent low temperature heat sealing property and hot tack property.

Examples 3 and 4 The H ₂ concentration in the polymerization tank was 0.36 vol.%, The butene-1 concentration was 23 vol.% (Example 3), and the H ₂ concentration in the polymerization layer was 0.
25 vol.%, Butene-1 concentration 25 vol.% (Example 4)
A copolymer was obtained under the same polymerization conditions as in Example 1 except that The butene-1 contents of the obtained copolymer were 22.7% by weight and 24.9% by weight, respectively. (Table 1) Table 2 shows the physical properties of the laminated stretched film that was pelletized under the same conditions as in Example 1, laminated and stretched.
Shown in. All of them showed excellent low temperature heat sealing property and hot tack property.

Comparative Examples 1 and 2 The H ₂ concentration in the polymerization tank was 1.5 vol.%, The butene-1 concentration was 25 vol.% (Comparative Example 1), and the H ₂ concentration in the polymerization layer was 1.6.
A propylene-butene-1 copolymer was obtained according to Example 1 of JP-B-2-57770, except that the vol.% and butene-1 concentrations were changed to 28 vol.% (Comparative Example 2). (Table 1) Pelletization under the same conditions as in Example 1 of the present application, lamination processing,
Table 2 shows the physical properties of the stretched laminated film subjected to the stretching treatment. This laminated stretched film showed excellent low-temperature heat-sealing property, but had insufficient hot tack property.

Comparative Example 3 A copolymer was obtained under the same polymerization conditions as in Example 1 except that the H ₂ concentration in the polymerization tank was changed to 3.2 vol.% And the butene-1 concentration was changed to 21.5 vol.%. . The MFR of the obtained copolymer was 28.
g / 10 minutes, butene-1 content was 20.6% by weight. (Table 1) Table 2 shows the physical properties of the laminated stretched film that was pelletized under the same conditions as in Example 1, laminated and stretched.
This laminated stretched film showed good low-temperature heat-sealing properties, but hot tackiness was insufficient.

Comparative Example 4 A copolymer was obtained under the same polymerization conditions as in Example 1 except that the H ₂ concentration in the polymerization tank was changed to 0.25 vol.% And the butene-1 concentration was changed to 12 vol.%. (Table 1) The butene-1 content of the obtained copolymer is 12.0% by weight.
Met. Table 2 shows the physical properties of the laminated stretched film that was pelletized under the same conditions as in Example 1, laminated, and stretched. This laminated stretched film had insufficient low temperature heat sealability and hot tack property.

[0038]

[Table 1]

[0039]

[Table 2]

[0040]

According to the present invention, it is possible to provide a polypropylene laminated film having excellent low temperature heat sealability and hot tackiness.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location B29K 23:00 B29L 7:00 9:00 (72) Inventor Yoichi Obata 5 Anezaki coast, Ichihara city, Chiba prefecture 1 Sumitomo Chemical Co., Ltd. (72) Inventor Minoru Takane 5-1 Anezaki Kaigan, Ichihara, Chiba Sumitomo Chemical Co., Ltd.

Claims (2)

[Claims] 1. A catalyst system consisting of a solid catalyst component containing magnesium, titanium and halogen as essential components, an organoaluminum compound and an electron donating compound is used on at least one side of a crystalline polypropylene layer, and substantially no liquid medium is used. Propylene obtained by vapor phase polymerization in the presence of 4 carbon atoms
A polypropylene laminated film obtained by laminating a random copolymer with the above α-olefin and satisfying the following conditions (1) to (5). (1) The content of α-olefin having 4 or more carbon atoms in the copolymer is 15 to 30% by weight (2) The melt flow rate of the copolymer is 20 g / 10 minutes or less (3) The weight average molecular weight of the copolymer / Number average molecular weight is 4.
5 or less (4) The relational expression between the α-olefin content of 4 or more carbon atoms (A wt%) of the copolymer and the cold xylene-soluble part (B wt%) of the copolymer is B ≦ 1.05A-10. (5) α having 4 or more carbon atoms in the cold xylene-soluble part of the copolymer
-Olefin content is less than 1.7 times the α-olefin content of 4 or more carbon atoms of the copolymer. 2. An α-olefin having 4 or more carbon atoms is butene-
1. The polypropylene laminated film according to claim 1, which is 1.