JPS61215038A - Packaging film - Google Patents

Abstract

PURPOSE:To obtain the title film which is soft and strong and obtains excellent transparency, glossiness, blocking resistance and tear strength, by making use of a copolymer having a specific copolymer for its main ingredient and having specific characteristics. CONSTITUTION:A copolymer of propylene and alpha-olefin whose number of carbon atoms are four or more or that of propylene, alpha-olefin whose number of carbon atoms are four or more and ethylene is used. As for the alpha-olefin content, whose number of carbon atoms are four or more, of the copolymer and the ethylene content of the same, 8-25 mol% and less than 5 mol% are desirable respective ly, and as for a soluble part of cold xylene (CSX), 15-50wt% is desirable. As for a bending modulus of the copolymer, the same having that of 2,500-6,500 kg/cm<2> is used, and as for a film obtained, tear strength in a MD and TD directions are more than 7g, Young's modulus in the MD and TD directions are 2,000-7,000 kg/cm<2> and break strength at least in one direction is more than 400 kg/cm<2>.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is applicable to the field of packaging films which are flexible and have excellent strength in at least one direction, tear strength, transparency, gloss, and anti-blocking properties, and which also exhibit shrinkage and transparency over time. In the textile packaging film field, vinylon film has been used for many years. This is because vinylon film is flexible, has excellent transparency and gloss, and has excellent mechanical strength, etc., giving textile products a luxurious feel. However, disadvantages of vinylon film include that it is greatly affected by humidity, its properties vary widely depending on the season, such as being too soft during the rainy season and becoming hard in winter, and that it is expensive. It will be done.

For this reason, in recent years there has been active development of polyolefin-based fiber packaging films that are relatively inexpensive and are hardly affected by seasonal influences.

For example, packaging films that are flexible and have relatively good transparency and gloss have been developed by processing linear low-density polyethylene (LLDP E) with water-cooled blown silon film or T-guicast film. ing. However, L1. The DPE film has the disadvantage that its transparency and gloss are still at a slightly inferior level compared to vinylon film, and the strength of the film is significantly lower.

Among propylene resins, 3 to 5 wt of ethylene
It is well known that by processing the propylene random copolymer copolymerized to the above film into a packaging film that is relatively flexible and has excellent transparency and gloss, the strength of the film is It has the disadvantage of being significantly lower than vinylon film. If stretching is performed to improve the strength of this film, the strength will be improved, but the flexibility of the film will be lost and the tear strength will be extremely poor, which is a practical problem. To prevent the film from losing its flexibility even after stretching, ethylene (3w
When a copolymer containing t % (9 molt) or more is used, the stretched film exhibits a whitening phenomenon, loses transparency and gloss, and still has a problem of poor tear strength.

On the other hand, among propylene resins, propylene-butene-
It is known that a film with good transparency can be obtained by stretching a random copolymer.
3-113692) The present inventor conducted additional tests and found that although the transparency was certainly good immediately after stretching, the transparency gradually deteriorated over time, and furthermore, the Young's modulus of the film increased. Even if it has moderate flexibility, it has extremely poor tear strength and poor blocking resistance, and it gradually shrinks over time in the summer. Wrinkles are likely to occur during fusing and sealing, which poses a practical problem as a film for high-grade textile packaging.

In view of the above circumstances, the inventors of the present invention have conducted extensive studies, and have found that, surprisingly, specific processing conditions can be achieved by using a copolymer with specific properties based on a specific comonomer. In addition, in combination with other specific processing conditions, the film is flexible and strong, has excellent transparency, gloss, and anti-blocking properties, has excellent tear strength, and has excellent resistance to shrinkage and transparency over time. The present invention was completed by discovering that a film without any deterioration phenomenon could be obtained.

That is, the present invention is a copolymer of propylene and an α-olefin having 4 or more carbon atoms, or a copolymer of propylene, an α-olefin having 4 or more carbon atoms, and ethylene, and the copolymer has 4 or more carbon atoms under the following conditions. The d-olefin content is 8 to 25 molar ■ The ethylene content of the copolymer is 5 molar or less ■ The cold xylene soluble portion of the copolymer is 15 to 5°WE% ■ The flexural modulus of the copolymer is 2500 to 6500 Ki
The present invention relates to a packaging film which consists essentially of a copolymer satisfying t' 7 cm2 and is stretched in at least one direction.

The first feature of the film obtained by the present invention is that it is flexible, does not deteriorate the transparency of the film over time, has good blocking resistance, and maintains excellent transparency and gloss forever. It is. The second feature is that it not only has excellent mechanical strength in at least one direction, but also has tear strength at a level that can withstand practical use, and can be fastened with hooks, which is often used in high-grade textile packaging film bags. be. Third
The characteristic of this is that while conventionally flexible stretched films had problems with shrinkage over time in the summer, the film of the present invention does not substantially shrink over time even though it is flexible, making it a high-quality fiber packaging film bag. The point is that it can be used for various purposes.

The present invention will be explained in detail below.

The copolymer used in the present invention can be produced by a solvent polymerization method in which the copolymer is polymerized in a solvent or a gas phase polymerization method in which the copolymer is polymerized in a gas phase. The phase polymerization method is economically superior because the polymer drying step or solvent purification step can be omitted or greatly simplified, and can be carried out using a special reactor or the like. In addition, it is essential that the polymerization be carried out under temperature and pressure conditions in which the gas does not liquefy in the reactor and the polymer particles do not melt into agglomerates. Particularly preferable polymerization conditions are 40 to 100°C. and a pressure range of 1 to 50 marks/cm2 (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 regulator such as hydrogen. Polymerization can be carried out by batch polymerization, continuous polymerization, or a combination of the two, and the monodisperse and molecular weight modifier consumed in the polymerization can be reacted continuously or intermittently. can be supplied to the container.

Further, after gas phase polymerization, it is also possible to wash with alcohols or hydrocarbon solvents for the purpose of removing catalyst residues or low molecular weight polymers.

The catalyst system used in the production of the copolymer used in the present invention is a so-called Ziegler-Natsuta catalyst, that is, a transition metal compound of Groups ■ to ■ of the periodic table, in order to suppress the ΔH ze of the resulting copolymer. The transition metal compound or the catalyst component containing the transition metal compound is preferably solid. The transition metal compound is preferably a compound containing at least titanium and a halogen, among which the general formula Ti(Ok)nXm=n (R represents a hydrocarbon group having 1 to 20 carbon atoms, X represents a halogen, and nl represents a 2 to 4,
A titanium halogen compound represented by n represents a number from 0 to m −1 is preferred.

A specific example of such a compound is T'iC,/4
．． TiCJ3. TiCJ2. Ti (QC2H6
)C/3°Ti (QC6H6)C/3, etc.

The transition metal compound itself can be the main component or can be used as a catalyst component supported on a suitable carrier.

Among titanium halogen compounds, T t C/3 is one of the most preferred transition metal compounds in the present invention, but it is known to take α, β, T, and δ crystal forms, and has 3 or more carbon atoms. For stereoregular polymerization of α-olefins, α-, T- and δ-type Ti CZ3 having layered crystallinity are preferred. T s CZ 3 is generally T
T t CZ 3 compositions are generally obtained by reducing t CZ4 with hydrogen, metallic aluminum, metallic titanium, organoaluminum compounds, organomagnesium compounds, and the like.

A preferred TtC/3 composition is the so-called TtC1! which is activated by reducing TrC/4 with metallic aluminum and further mechanically grinding or the like. a A A and Tt
CZ4 is reduced with an organoaluminium compound and further activated using a complexing agent and a halogen compound.

In the present invention, the latter is particularly preferred.

Also, trivalent titanium containing an alkoxy group obtained by reducing Ti(OR) 4 (k represents a hydrocarbon group having 1 to 20 carbon atoms) with an organoaluminum compound and then treating it with an ether compound and T*C1!4. Halides can also be suitably used.

T x C/3 composition or alkoxy group-containing trivalent titanium halide produces polypropylene of 6.00011 or more per gram when polymerized at 65°C for 4 hours in liquefied propylene in the presence of hydrogen in combination with diethylaluminium chloride. Particularly preferred are those that can be Such a T iC/3 composition is disclosed in JP-A-47-344.
Publication No. 78, Japanese Patent Publication No. 55-27085, Japanese Patent Application No. 1978
It can be manufactured by the method disclosed in Japanese Patent Application No. 7-26508, Japanese Patent Application No. 138471/1980, and the like.

Further, a trivalent titanium halide containing an alkoxy group can be produced by the method disclosed in Japanese Patent Application No. 57-221659.

When a transition metal compound is used as a catalyst component supported on a suitable carrier, various solid polymers, especially α
- Polymers of olefins, various solid organic compounds, especially solid hydrocarbons, various solid inorganic compounds, especially oxides, hydroxides, carbonates, halides, etc. can be used.

Preferred carriers are magnesium compounds, ie, magnesium halides, oxides, hydroxides, hydroxyhalides, and the like. Magnesium compounds can also be used as complexes with other solid substances mentioned above. Commercially available magnesium compounds can be used as they are, but they can be mechanically pulverized, dissolved in a solvent and then precipitated, treated with an electron-donating compound or active hydrogen compound, or treated with an organomagnesium compound such as Grignard reagent. A magnesium compound obtained by decomposing is preferable.

In many cases, it is preferable to use these operations in combination to obtain a preferable magnesium compound, and these operations may be carried out in advance when producing the carrier, or may be carried out when producing the catalyst component. Particularly preferred magnesium compounds are halogenated magnesium compounds, and particularly preferred transition metal compounds are the aforementioned halogenated titanium compounds. The supported catalyst component containing titanium, magnesium, and halogen as main components is one of the most preferred catalyst components in the present invention, and is disclosed in Japanese Patent Application Laid-Open No. 56-304.
It can be manufactured by the method disclosed in Japanese Patent Application Laid-open No. 07, Japanese Patent Application Laid-Open No. 57-59915, and the like.

In order to highly stereoregularly polymerize an α-olefin having 3 or more carbon atoms, an electron-donating compound is contained among these,
It is preferable to use a supported catalyst component whose main components are titanium, magnesium, and metal.

Preferable examples of typical metal organic compounds in Groups 1 to 2 of the Periodic Table are organic compounds of aluminum, especially those with the general formula R.
An organoaluminum compound represented by eAlX3-e (k is a hydrocarbon group having 1 to 20 carbon atoms, X is hydrogen or halogen, and e is a number from 1 to 3) is preferred.

Specific examples of such compounds include triethylaluminum, triisobutylaluminum, diethylaluminum hydride, diethylaluminum chloride, diethylaluminum bromide, ethylaluminum sesquichloride, and ethylaluminum dichloride.

The most preferred compounds are triethylaluminum, diethylaluminum chloride and mixtures thereof.

Electron-donating compounds used in the synthesis and polymerization step of the solid catalyst component in the present invention include ethyl acetate, ε-caprolactone, methyl methacrylate, ethyl benzoate, P
- Esters or acid anhydrides such as ethyl anisate, P-1 methyl tolyate, phthalic anhydride, ether compounds such as di-n-butyl ether, diphenyl ether, digram, tri-n-butyl phosphite, triphenyl phosphite, hexa Examples include organic phosphorus compounds such as methylene phosphoric triamide. In addition, ketones, amines, amides, thioethers, and organosilicon compounds such as alkoxysilanes or aryloxysilanes having a 5i-0-C bond can also be used.

Furthermore, the solid catalyst component may be prepolymerized by treating it with a small amount of olefin in the presence of an organoaluminum compound or an electron-donating compound before polymerization.

The copolymer used in the present invention uses an α-olefin having 4 or more carbon atoms or a small amount of ethylene as a comonomer. Examples of α-olefins having 4 or more carbon atoms include butene-1, pentene-1, hexene-1,4-methylpentene-1, etc. alone or in combination; Butene-1 is the most preferable because it is difficult to use and can maintain a high partial pressure.

If the main component of the comonomer is ethylene or if it contains more than a certain amount of ethylene, problems such as poor transparency or deterioration of film transparency over time, which may be due to bleeding of atactic components, may occur. Problematic and undesirable.

The content of the α-olefin having 4 or more carbon atoms in the copolymer used in the present invention is 8 to 25 mol, preferably 10 to 22 mol.

If the content of α-olefin having 4 or more carbon atoms is below the lower limit, the flexibility of the film will be lost, which is undesirable; if it exceeds the upper limit, the film will shrink over time, and the film will be too soft. Also, the transparency of the film deteriorates over time, and the blocking resistance and tear strength are deteriorated, which is undesirable.

The ethylene content of the copolymer used in the present invention is 5 molti or less, preferably 3 molti or less. If the ethylene content exceeds the upper limit, the transparency of the film deteriorates over time, even if the content of α-olefin having 4 or more carbon atoms is relatively small, which is not preferable. The reason for this is not clear, but when the comonomer is ethylene, α
- This seems to be because there is more bleeding of atactic components compared to the case of olefins.

For copolymerization, a random copolymer in which monomers and comonomers are simultaneously supplied and polymerized is preferably employed, but polymerization can also be carried out by changing the composition of monomers that are polymerized stepwise or continuously.

The cold xylene soluble part (CXS) of the copolymer used in the present invention
) is 15-5 Q wt% and 17-40 wt%
is more preferable. If CXS is below the lower limit, even if the comonomer content is higher than the lower limit, the copolymer will lose its softness and the film will lose its flexibility, which is undesirable. If the limit is exceeded, the film becomes too soft, shrinks over time, the transparency of the film deteriorates over time, and the blocking resistance and tear strength are poor. The ΔHaze of the copolymer is 7% or less, preferably 5% or less, and more preferably 4% or less.

If ΔH a ze exceeds the upper limit, the transparency of the film will deteriorate over time, and the blocking resistance will also deteriorate, which is not preferable.

The boiling n-hebutane insoluble part of the copolymer used in the present invention (
BHIP) does not need to be limited, but is preferably 7wL% or more.

When a copolymer containing less than 7 wt% of BIIIP is used, blocking of the film becomes somewhat worse.

The flexural modulus of the copolymer used in the present invention is 2.500~
6,500 instant/C+I+2, 3,000~6,
000 marks/cm2 is preferable. If the flexural modulus of the copolymer is below the lower limit, the film will be too soft, shrink over time, and have poor tear strength and blocking resistance, which is undesirable. If the film is stretched in excess of
The tear strength is also poor, which is not preferable.

It is generally known that stretching deteriorates tear properties, but the α-olefin content of the copolymer, CXS,
By specifying the flexural modulus, etc. within the above-mentioned range, we opened the way to solving the problem of film shrinkage over time, and it became easier to perform low-strength stretching, and we were able to improve the tear strength. That is unexpected.

The copolymers used in the present invention may also be blended with small amounts of other polymeric materials. Additionally, additives such as antistatic agents, antiblocking agents, slip agents, and stabilizers can be added.

In the present invention, known processing methods such as the T-die casting method and the water-cooling inflation method can be employed as a method for forming the copolymer into a film. Further, as a method for performing the stretching process in at least one direction, known uniaxial stretching methods such as roll stretching and roll rolling, and known biaxial stretching methods such as flat biaxial stretching and tubular biaxial stretching can be adopted. However, biaxial stretching is preferable because a well-balanced film can be obtained.

Further, the copolymer of the present invention generally has the characteristic that a uniform thickness distribution can be obtained when stretched at a low magnification (although it can be stretched well at a low magnification even in a flat biaxial stretching method).

The stretching temperature is from room temperature to below the melting point of the copolymer,
100-130°C is preferred. The stretching ratio is 1.2
~5 times, preferably 1.3 to 4 times, ■. More preferably 5 to 3 times. If the stretching ratio is less than 2" above the upper limit, the tear strength of the film will be poor even if the above-mentioned properties of the copolymer are within the specified range, which is undesirable. If the stretching ratio is less than the lower limit, the strength of the film will be insufficient. I don't like it. Further, in order to increase the effect of preventing the film from shrinking over time, it is preferable to perform heat setting (annealing) after stretching.

The heat setting conditions are preferably (stretching temperature -10)°C or higher, more preferably 110°C or higher.

As for the physical properties of the film thus obtained, the tear strength is 7 gu or more, preferably 10 g or more, and 15. More preferably, it is F or higher. If the tear strength is below the lower limit, it is undesirable because it is likely to be torn from the hooked part. In addition, the Young's modulus of MD and Tb is 2
．． 000 to 7,000 K9/cm2, preferably 2,000 to 6,000 Kl! /cm2 is more preferable.

When the Young's modulus of the film is below the lower limit, it is undesirably too soft compared to vinylon film, and when it is below the upper limit, it loses the flexibility of vinylon film, which is undesirable. Further, the strength at break in at least one direction of the film is preferably 400 Q/cm2 or more.

If this strength is less than 400 Kg/cm2, the hook resistance (as the hook of the bag is opened and closed many times, the film stretches in the opening and closing direction and loses its commercial value) becomes undesirable. .

The shrinkage rate of a propylene film generally corresponds to Young's modulus, but according to the method of the present inventors, it is possible to provide a film with a small shrinkage rate even if the Young's modulus is the same.

That is, the shrinkage characteristics of the film of the present invention include the shrinkage rate at 100°C (Y1%) and Young's modulus (X.

F4! /α2) satisfies the following inequality.

Y<50-0.0035X Further, it is preferable that the following inequality is satisfied.

Y < 35-0.002 Therefore, the present invention provides an excellent film that is more flexible and does not shrink over time compared to known methods.

The propylene copolymer packaging film produced as described above has flexibility, transparency, and gloss properties that are very similar to those of vinylon film, and can be processed with hooks. It has extremely great practical value as there is almost no change in physical properties depending on the season, and it can be manufactured at a low cost.

In addition, the data and evaluation in Examples and Comparative Examples were performed according to the following method.

(1) The α-olefin content in the copolymer was determined from the mass balance. Furthermore, the content of butene-1 was further determined by a conventional method using an infrared spectrophotometer from characteristic absorption at 770 cm' to confirm the mass balance results. In addition, in the measurement using an infrared spectrophotometer needle, a calibration curve was prepared and quantified based on quantitative values by C-NMR for propylene-butene-1 copolymer.

(2) Ethylene content in the copolymer was determined from the mass balance. Furthermore, using an infrared spectrophotometer, 7
32CIl+-1,720 cm'' was quantified using a conventional method to confirm the mass balance results.For measurements using an infrared spectrophotometer, a calibration curve was created using the quantitative values obtained by radiation measurement of ethylene copolymer labeled with 14C. and quantified.

(3) Cold xylene soluble part (CXS) polymer 5g
is dissolved in 500 rnl of xylene and then slowly cooled to room temperature. Then, the mixture is left in a bath at 20° C. for 4 hours, filtered, and the filtrate is concentrated, dried, and weighed.

(4) Intrinsic viscosity ([η]) Tetralin was measured at 135°C by a conventional method at four different concentrations: 0.4°0°2,0°133 and Ool 11/dl.

(5) Create a press sheet of △Haze copolymer with a thickness of 100μ, and
It was expressed as the difference between the haze after annealing treatment at °C for 9 hours and the haze before treatment.

(6) Flexural modulus Conforms to ASTM-D 7g6.

However, sample shape: 2 mmt x 2 Om medium x 50 length span distance: 30 yen + Il + i/min (7) Young's modulus of film conforms to ASTM-D 882.

However, test piece shape: 20 x 120 strips Distance between chucks: 50+1111 Tensile speed: 5 mm/min (8) Film tensile properties conform to ASTM-D 882.

However, tensile speed: 200 M/min (9) Haze value (Haze) Based on ASTM-D 1003.

OQ Gross Conforms to ASTM-D523.

Qll Tear strength Conforms to JISK6772.

az blocking 7K per 100cm2 of overlapping two films
Conditioning was carried out at 23° C. for 24 hours while applying a load of f.

After that, the two films were peeled off at a load increase rate of 101/min in the direction perpendicular to the film surface, and the maximum load at that time (,
Fl is determined and expressed in terms of film area 100CI112.

(13) Shrinkage rate Shown as the dimensional change rate when immersed in a glycerin bath at 100°C for 30 seconds.

Hereinafter, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited to the examples unless it goes beyond the gist thereof.

Example 1 (1) Preparation of solid catalyst containing titanium trichloride After purging an 11-capacity flask equipped with a stirrer and a dropping funnel with argon, ethylaluminum was added to a solution consisting of 60% of titanium tetrachloride and 228% of n-hebutane. sesquichloride 136
．． A solution consisting of 6- and n-hebutane 300-
The mixture was added dropwise at −10° C. over 2 hours.

After the dropwise addition was completed, the mixture was stirred at room temperature for 30 minutes, then heated to 80°C, and heat-treated at 80'C for 1 hour. Then, the mixture was allowed to stand at room temperature and subjected to solid-liquid separation, and then washed four times with n-hebutane 400°C.

Next, 580 ml of n-hebutane. Pour 5 tnl of diethyl aluminum chloride into the flask and set the temperature to 50°C.
I kept it. While stirring, 32 g of propylene was gradually fed into the suspension at 50° C. for 2 hours to perform a preliminary polymerization treatment.

After the treatment, solid-liquid separation was performed, and washing was repeated twice with 400 kg of n-heptane.

Next, add 392 - of toluene to the flask and lower the temperature to 8
It was kept at 5°C. While stirring, add n-butyl ether 11
7rnl and 3.7-tri-n-octylamine were added and reacted at 85°C for 15 minutes. After reaction, iodine 15.5
Add a solution of II in 196 ml of toluene,
The reaction was further carried out at 85°C for 45 minutes.

After the reaction, solid-liquid separation was performed, and once with 500 rnl of toluene,
After repeating washing three times with 500 d of n-hebutane, the mixture was dried under reduced pressure to obtain 90 g of a titanium trichloride-containing solid catalyst. Titanium trichloride in the solid catalyst containing titanium trichloride is 65.2
It contained % by weight.

(2) Copolymerization Propylene and butene-1 were copolymerized using a fluidized bed reactor equipped with a stirrer and having an internal volume of 1 m3. First, 609% of propylene-butene-1 copolymer particles for catalyst dispersion were fed into the reactor, and then the reactor was purged with nitrogen and then with propylene. 5 Ky/cm with propylene
The pressure was increased to 2G and circulating gas was supplied from the bottom of the reactor at a flow rate of 80 m''/hr to keep the polymer particles in a fluidized state, and then the following catalyst was supplied to the reactor.
, fCl used a solution diluted with hebutane.

(a) Titanium trichloride-containing solid catalyst 21 g
(bl diethylaluminum chloride 11
2g (C) Triethylaluminum 11.9
+d+ Methyl methacrylate 8g, then hydrogen concentration 1. 't vol%, butene-120
Hydrogen, propylene, and butene-1 were supplied to give a concentration of (1) 0%, the pressure was increased to IOKli'/cm2G, and the temperature of the fluidized bed was adjusted to 65°C to initiate polymerization. During the polymerization, hydrogen, propylene, and butene-1 were supplied so as to keep the concentration and pressure of hydrogen and butene-1 constant. Polymerization amount is 75K
When reaching Q, 60% of the polymer particles remained in the reactor for catalyst dispersion in the next polymerization, the remaining polymer particles were transferred to a stirring mixing tank, 210y of propylene oxide and 100g of methanol were added, and the temperature was heated to 80°C. It was treated for 30 minutes. It was then dried to obtain a white powdery polymer. The same polymerization was repeated three times, and the physical properties of the finally obtained polymer were measured.

The butene-1 content of this copolymer was 17.3 molti, C
XS is 29°6 wt%, and the intrinsic viscosity is 1.9 dl/
g, flexural modulus is 4100/12, △Haze is 2.
It was 0%.

(3) For the copolymer obtained in film molding (2), a thick film with a thickness of 270 μm was obtained under the following molding conditions.

Extruder: Manufactured by Egan Co., Ltd. 65 Cocoon extruder Screw: Single full flight type L/I)-24c, t
t=4.0 Temperature condition: 230℃ Die: Coat hanger die lip opening 0°9TWn Medium 500 adjustment molding speed = 3
m/min This original film was stretched under the following stretching conditions to obtain a biaxially stretched film with a thickness of 30 μm.

The physical properties of the film are shown in Table 1.

Stretching machine: Tenter biaxial stretching machine (manufactured by Nippon Steel) Stretching conditions: 2-person side Line speed: 3 m/min Output side
9m/min MD stretching ratio 3x TI) 0 3x Temperature conditions: MD stretching l no'cTD 〃 Preheating zone 120℃ Stretching zone 120℃ Annealing zone 120℃ This biaxially stretched film has flexibility, transparency, and gloss. excellent,
Furthermore, the film had sufficient tensile strength to enable hooking in both the MD and TD directions, and sufficient tear strength to withstand tearing from the hook, and was free from the risk of gradual shrinkage over time. .

Example 2 A copolymer was obtained using the catalyst system used in Example 1 under the same polymerization conditions as in Example 1 except that the amount of butene-1 used was changed. The butene-1 content of the obtained copolymer was 14.6 mol%, the CXS was 24.8 wt%, and the intrinsic viscosity was 1°8.
dl/I, flexural modulus is 53001QF/cm2,
ΔHaze was 0.3%. Under the stretching conditions shown in Example 1 for this copolymer, the temperature condition was 125°C.
A biaxially stretched film was obtained under the same conditions.

The physical properties of the film are shown in Table 1. This film is Example 1
It was a good film, similar to the film obtained in .

Example 3 A copolymer was obtained under the same polymerization conditions as in Example, except that the catalyst system used in Example 1 was changed, such as the amount of butene-1 and the addition of ethylene. The resulting copolymer had a butene content of 12.5 mol% and an ethylene content of 1.
4 mol strip, CXS is 32°7 wt%, intrinsic viscosity is 1.9 dl#, flexural modulus is 3900 Ky/cv
I2, ΔI-1a ze was 2.8%. A biaxially stretched film was obtained from this copolymer under the same conditions as those shown in Example 1. The physical properties of the film are shown in Table 1. Similar to Example 1, this film was a good film.

Comparative Example 1 A biaxially stretched film was obtained using the copolymer used in Example 1 under the same conditions as in Example 1, except that the stretching ratio was changed to 4 times MD and 7 times TD. Incidentally, an original film having a thickness of 840 μm was used. The physical properties of the film are shown in Table 1.

This film had poor flexibility and poor tear strength, making it difficult to put it to practical use.

This shows that even if the copolymer complies with the spirit of the present invention, a good film cannot be obtained unless the stretching ratio falls within the range that complies with the spirit of the present invention.

Comparative Example 2 A copolymer was obtained under the same polymerization conditions as in Example 1, except that the catalyst system used in Example 1 was replaced with ethylene instead of butene-1.

The ethylene content of the obtained copolymer was 11.6 mol%,
cxs is 27. I WE staff, the intrinsic viscosity is 1.8 dl
/11, flexural modulus is 2,800 Q/cm 1△Ha
ze was 18°3%. A biaxially stretched film was obtained from this copolymer under the same stretching conditions as in Example 1 except that the temperature condition was changed to 100°C. This film had poor transparency, and the transparency deteriorated significantly over time, making it difficult to put it to practical use.

Comparative Example 3 This copolymer was obtained by a slurry polymerization method using n-hebutane as a solvent, and the atactic component soluble in n-hebutane was removed. The ethylene content of this copolymer is 9.5 mol%, and the CXS is 9.6 wt.
%, intrinsic viscosity number is 1.8 dl/I, flexural modulus is 49
00 immediate/draw 2, ΔHaze was 1.2 chi.

A biaxially stretched film was obtained from this copolymer under the same conditions as those shown in Example 1. The physical properties of the film are shown in Table 1. This film exhibited a whitening phenomenon during stretching and had poor transparency.

Comparative Example 4 This copolymer was obtained by a slurry polymerization method using n-hebutane as a solvent, and components soluble in n-hebutane were removed. The butene-1 content of this copolymer is 14.3 mol%, the CXS is g, 5 wt%, the intrinsic viscosity is 1.9 dl/I/, and the flexural modulus is 7300.
Q/cm2 and △Haze were 1°5. For this copolymer, the temperature conditions were changed to 1 under the stretching conditions shown in Example 1.
A biaxially stretched film was obtained under the same conditions except that the temperature was changed to 25°C. However, compared to Example 1.2.3, the obtained film was
The thickness distribution in the TD force direction was quite poor. The physical properties of the film are shown in Table 1. This film had poor flexibility and tear strength.

Comparative Example 5 (1) Synthesis of solid product After purging a flask with an internal volume of 500 mm equipped with a stirrer and a dropping funnel with argon, 83 rnl of n-hebutane, 1 ml of titanium tetrachloride and 1 ml of tetra-n-butoxy were added. 51.0 m7 of titanium was charged into a flask, and the temperature inside the flask was maintained at 20°C while stirring. n-hebutane 16
2.14 and diethylaluminum chloride 37°8ml
The solution was gradually added dropwise from the dropping funnel over 3 hours while maintaining the temperature inside the flask at 20°C. After the dropwise addition was completed, the temperature was raised to 50°C and stirred for 1 hour. After standing at room temperature for solid-liquid separation and repeated washing with 2001 nl of n-heptane four times, drying under reduced pressure yielded a reddish-brown solid product of 64.7 ml.
, got F.

(2) Synthesis of prepolymerized solids After purging a 300-capacity flask equipped with a stirrer with argon, 241 g of n-heptane, 0.34 g of triethylaluminum, and 19.7 g of the solid product prepared with GAI were added. The mixture was poured into a flask and the temperature was maintained at 50°C.

Next, while stirring, ethylene was added at a partial pressure of 0.2 Kip/
While maintaining the temperature at cm 2 , the mixture was gradually fed into the suspension at 50° C. for 20 minutes to carry out preliminary polymerization. After the treatment, the solid-liquid was separated, washed twice with 50% of n-hebutane, and then dried under reduced pressure. The amount of prepolymerization was 0.09 F of polymer per solid product II.

(3) Synthesis of solid catalyst component After purging a flask with an internal volume of 100 cm with argon, 12.1 g of the prepolymerized solid prepared above and 42.3 m/n-hebutane were charged into the flask, and the contents of the flask were The temperature was kept at 30°C. Next, di-iso-amyl ether 14.4- was added, treated at 30°C for 1 hour, and then
The temperature was raised to 5°C. 15.7 ml of titanium tetrachloride was added at 75°C, and the reaction was carried out at 75°C for 1 hour. After solid-liquid separation, the mixture was washed four times with 50% of n-hebutane and dried under reduced pressure to obtain a solid component. Furthermore, after purging the flask with an internal volume of 100 ml with argon, the above solid component 9.9y and n-hebutane 38- were charged into the flask, and the temperature inside the flask was maintained at 30°C. Next, 8.5-di-iso-amyl ether was added and treated at 30°C for 1 hour.
The temperature was raised to ℃. 11.5-titanium tetrachloride was added at 75°C, and the reaction was carried out at 75°C for 1 hour. After solid-liquid separation, washing was repeated four times with 50 rnl of n-hebutane and then dried under reduced pressure to obtain a solid catalyst component.

(4) The autoclave for Copolymerization 1001 was equipped with a stirrer, a thermometer, a dropping funnel, and a reflux condenser, and the pressure was reduced, and the autoclave was replaced with nitrogen.

50f of normal hexane dried in this autoclave
was kept at a constant temperature of 50°C, and a mixed gas of 71 moles of propylene and 129 moles of butene was added to it at 0028 N.
Flow at a rate of m”/min.

Then, diethylaluminum chloride 30 was used as a catalyst.
．． F and 1.65 g of ε-caprolactone are added, followed by 3 g of the solid catalyst obtained in (3) above to initiate polymerization. Polymerization was carried out by continuously flowing a mixed gas of propylene and butene-1 for 120 minutes while stirring. Next, 1.51 g of butanol was added to stop the reaction, and after thorough washing with butanol, the reaction product was poured into a large amount of methanol to precipitate a copolymer. The intrinsic viscosity of this copolymer is 2.
2 dl/I, the butene-1 content is 26°5 molar, CXS is 56 wt, and the flexural modulus is 2.
200 Q/cm2, and ΔHaze was 3°5.

(5) Film forming A biaxially stretched film was obtained from the copolymer obtained in (4) above under the same stretching conditions as in Example 1 except that the temperature condition was changed to 90°C. (Note that if the temperature exceeds 90° C., adhesion to the line becomes a problem and is difficult.) The physical properties of the film are shown in Table 1. This film has an extremely large blocking of 100.9/100α2 or more (the film in the example has a value of 201/100 cm2 or less), and its tear strength is not very good, and moreover, it shrinks over time in the summer, making it difficult to put into practical use. It wasn't a film I could offer.

Procedural amendment (voluntary) April 9, 1986

Claims (8)

[Claims] (1) A copolymer of propylene and an α-olefin having 4 or more carbon atoms or a copolymer of propylene, an α-olefin having 4 or more carbon atoms, and ethylene under the following conditions 1 to 4 [1] If the copolymer has 4 or more carbon atoms α-olefin content is 8 to 25 mol%, [2] ethylene content of the copolymer is 5 mol% or less, [3] cold xylene soluble portion of the copolymer is 15 to 50 wt%
, [4] The flexural modulus of the copolymer is 2500 to 6500 kg
A packaging film consisting essentially of a copolymer satisfying the following: /cm^2 and subjected to a stretching process in at least one direction. (2) The packaging film according to claim 1, which has a tear strength of 7 g or more in the MD and TD directions. (3) Young's modulus in MD and TD direction is 2000-700
0 Kg/cm^2 and a breaking strength in at least one direction of 400 Kg/cm^2 or more. (4) Shrinkage rate (Y, %) and Young's modulus (X,
The packaging film according to claim 1, 2, or 3, wherein the relationship with Kg/cm^2) satisfies the following inequality. Y<50-0.0035X (5) The packaging film according to claim 1, 2, 3, or 4, wherein the copolymer has a ΔHaze of 7% or less. (6) Claims 1, 2, and 3, wherein the α-olefin having 4 or more carbon atoms in the copolymer is butene-1,
Packaging film as described in paragraph 4 or paragraph 5 (7) Claims 1, 2, 3, and 4 are subjected to a stretching process with a stretching ratio of 1.2 to 5 times.
The packaging film according to item 5 or 6. (8) The packaging film according to claim 1, 2, 3, 4, 5, 6, or 7, which is subjected to a stretching process called biaxial stretching.