JPS61213244A - Packaging film - Google Patents

Abstract

PURPOSE:To produce a packaging film having improved transparency and strength, by blending a crystalline polypropylene to a copolymer composed of propylene, an alpha-olefin and optionally ethylene, and drawing the obtained particular composition along at least one direction. CONSTITUTION:(A) A copolymer composed of propylene, 8-35mol% >=4C alpha- olefin (preferably butene-1) and if necessary <=5mol% ethylene, and having a cold xylene soluble content of 15-80(wt)% and a DELTAHaze of <=7% is blended with (B) a crystalline polypropylene at a ratio (A:B) of (30-95%):(70-5%) to obtain a composition having a flexural modulus of 2,500-6,500kg/cm<2>. The composition is drawn along at least one direction, preferably drawn biaxially to obtain the objective packaging film having a tear strength of >=7g along MD and TD directions, a Young's modulus of 2,000-7,000kg/cm<2> and a tensile strength at fracture of >=400kg/cm<2> along at least one direction.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is applicable to the field of packaging films that are flexible and have excellent strength in at least 61 directions, tear strength, transparency, gloss, and anti-blocking properties, and also have excellent shrinkage and transparency over time. However, vinylon film has been used for many years in the textile packaging film field. 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, the disadvantages of vinylon film are that it is greatly affected by humidity, and its properties vary widely depending on the season; it becomes too soft during the rainy season, but becomes too hard in winter, and it is also expensive. can be given.

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 (LLDPE) with water-cooled blown silon film or T-guicast film. ing.

However, the LLDPE film obtained by this processing method 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, ethylene is 8 to 5 wt%
It is well known that by processing the propylene random copolymer that has been partially copolymerized into the film described above, a relatively flexible packaging film with excellent transparency and gloss can be obtained. It has the disadvantage of being significantly lower than 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 poses practical problems. If a copolymer containing 5 wt% (9 mol%) or more of ethylene is used so that the film does not lose its flexibility even after stretching, a whitening phenomenon is observed in the stretched film and the film becomes transparent. The problem is that the glossiness is lost and the tear strength is still poor.

On the other hand, among propylene resins, a large amount of propylene
It is known that a film with good transparency can be obtained by stretching a butene-1 random copolymer and a small amount of isotactic polypropylene composition (Japanese Patent Publication No. 57-24875). It was found that the transparency was good immediately after stretching, but
Transparency gradually deteriorates over time, and the Young's modulus of the film is too high, resulting in poor flexibility and extremely poor tear strength, and there is a risk of gradual shrinkage over time in summer. This poses a practical problem as a high-grade fiber packaging film.

In view of the above circumstances, the present inventors have made extensive studies and found that in a blend composition of a specific copolymer mainly composed of a specific comonomer and crystalline polypropylene, the copolymer is Surprisingly, the blend composition containing the above can obtain a uniform thickness distribution even when stretched at low magnification, has excellent tear strength, is flexible and strong,
Transparency, glossiness and anti-blocking? The present invention was completed by discovering that it is possible to obtain a film with excellent properties and no deterioration of transparency over time.

That is, the present invention is a copolymer of propylene and an α-olefin having at least a few carbon layers, or a copolymer of propylene, an α-olefin having at least a few carbon layers, and ethylene under the following conditions ■ to ■ ■ The number of carbon layers of the copolymer The above α-olefin content is 8 to 85 mol% ■ The ethylene content of the copolymer is 6 mol % or less ■ The cold xylene soluble portion of the copolymer is 15 to 80 wt% Copolymer A satisfying the following conditions: 80 to 95 wt% % and crystalline polypropylene B and 70 to 5 wt % of crystalline polypropylene B, and the resin composition has a flexural modulus of 2.500 to 6,500 Kl/csi, and is stretched in at least one direction. be.

The first characteristic 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. be. The second feature is that it has excellent mechanical strength in at least one direction, and its tear strength is at a level that can withstand practical use, allowing it to be fastened with hooks, which is often used in high-grade textile packaging film bags. .

The eighth feature is that there is virtually no shrinkage over time and the film can be used for high-grade textile packaging film bags.

The present invention will be explained in detail below.

The copolymer A used in the present invention can be produced by a solvent polymerization method in which polymerization is carried out in a solvent or a gas phase polymerization method in which polymerization is carried out in a gas phase. In particular, copolymer A is produced under conditions where a liquid solvent is substantially absent. The gas phase polymerization method is economically advantageous because the polymer drying step or solvent purification step can be omitted or greatly simplified, and can be carried out using a 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. temperature range and 1 to 60 Kt/cd (gauge pressure, hereinafter referred to as G
) is the pressure range. 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 either batchwise or continuously.
It is possible to carry out the polymerization by either polymerization or a combination of the two, and the monomer and molecular weight regulator consumed in the polymerization can be continuously or intermittently supplied to the reactor. I can do it.

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 copolymer A used in the present invention is a so-called Ziegler-Natsuta catalyst, that is, a transition metal compound of groups Y to II of the periodic table, in order to suppress the △Haze of copolymer A obtained. A catalyst comprising an organic compound of a typical metal of Group 1-1 of the Periodic Table, and the transition metal compound or the catalyst component containing the same is solid.

is preferred. Preferably, the transition metal compound is a compound containing at least titanium and a halogen, among which compounds having the general formula Ti(OR)n''m-n (R is a hydrocarbon group having 1 to 20 carbon atoms, and X represents a halogen) ,
A titanium halogen compound represented by m is a number from 2 to 4 and n is a number from 0 to m-1 is preferred. A specific example of such a compound is TiCz4. TiC
zs.

TiC2, Ti(OCgHs)Czs, Ti(
OC@Ha) C2a r (There is a tochi.

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

Among the titanium halogen compounds, TiC2a is one of the most preferred transition metal compounds in the present invention, but a,
It is known to take β, r and δ crystal forms,
In order to stereoregularly polymerize α-olefins having 8 or more carbon atoms, α-, γ-, and δ-type Ti having layered crystallinity are used.
Cts is preferred. TiCzs is generally obtained as a TiCzs composition by reducing TiCta with hydrogen, metallic aluminum, metallic titanium, organoaluminum compounds, organomagnesium compounds, etc.

A preferred TiCts composition is one in which TiCz4 is reduced with metal aluminum, so-called TiCza AA and TiCzt activated by mechanical grinding or the like are reduced with an organoaluminium compound, and further activated with a complexing agent and a halogen compound. be. In the present invention, the latter is particularly preferred.

Also suitable is an alkoxy group-containing octavalent titanium halide obtained by reducing Ti(OR)4 (R represents a hydrocarbon group having 1 to 20 carbon atoms) with an organoaluminum compound and then treating it with an ether compound and TiCz4. It can be used for.

TiCzs composition or alkoxy group-containing octavalent titanium halide produces polypropylene of 6.000 y or more per 1f when polymerized for 4 hours at 65"C in liquefied propylene in the presence of hydrogen. Particularly preferable are TiCzs compositions that can be used to increase the amount of water.
It can be manufactured by the method disclosed in Japanese Patent Application No. 6508, Japanese Patent Application No. 58-188471, etc.

Further, an alkoxy group-containing octavalent titanium halide 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. A 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. 56-8040.
It can be manufactured by the method disclosed in Japanese Patent Application Laid-Open No. 57-59915 and the like.

In order to highly stereoregularly polymerize α-olefins having 8 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 halogen.

Preferred organic compounds of Group 1-II typical metals of the periodic table are organic compounds of aluminum, particularly those having the general formula RekLIC@-6 (R is a hydrocarbon group having 1 to 20 carbon atoms, and X is hydrogen or halogen). (where e is a number from 1 to 8) 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, C-caprolactone, methyl methacrylate, ethyl benzoate, p
- Esters or acid anhydrides such as ethyl anisate, methyl p-toluate, phthalic anhydride, i) ether compounds such as -n-butyl Examples include organic phosphorus compounds such as phenyl phosphite and hexamethylene 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.

Copolymer-8 used in the present invention uses an α-olefin having at least several carbon layers or a small amount of ethylene as a comonomer. α-olefins having more than one carbon layer include butene-1, pentene-11, hexene-1,4
Examples include -methylpentene-1 alone or in combination, but in the case of gas phase polymerization, butene-1 is most preferred since it is difficult to liquefy 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 α-olefin having at least several carbon layers in the copolymer A used in the present invention is 8 to 85 mol%, preferably 10 to 80 mol%. If the α-olefin content of several carbon layers or more falls below the lower limit, the softness of the copolymer A will be lost and the flexibility of the film will be lost, which is undesirable, and if it exceeds the upper limit, the film will It is undesirable because it is too soft, the transparency of the film deteriorates over time, and the blocking resistance and tear strength are poor.

The ethylene content in the copolymer used in the present invention is 5 mol% or less, preferably 8 mol% or less. If the ethylene content exceeds the upper limit, the transparency of the film deteriorates over time, which is not preferable, even if the content of α-olefins having several carbon layers or more is relatively small. Although the reason for this is not clear, it is thought that when the comonomer is ethylene, the atactic component bleeds out more than when the comonomer is α-olefin having several carbon layers or more. 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 stepwise or continuously by changing the composition of the monomers to be polymerized.

The cold xylene soluble portion (CX
S) 1. t 15-80wt% tear l), 17-7
Q wt% is preferred. If CxS is below the lower limit, even if the comonomer content is within the above lower limit, the softness of copolymer A will be lost and the flexibility of the film will be lost, which is undesirable. If the upper limit is exceeded, the film becomes too soft, the transparency of the film deteriorates over time, and the blocking resistance and tear strength are deteriorated, which is not preferable.

The ΔHaze of copolymer A used in the present invention is 7% or less, preferably 5% or less, and more preferably 4% or less.

When ΔHaze exceeds the upper limit, the transparency of the film deteriorates over time, and the blocking resistance also deteriorates, which is not preferable.

Although the boiling n-hebutane insoluble portion (B) iIP) in the copolymer used in the present invention is not limited, it is preferably 7Wt96 or more. When copolymer-8 containing less than 7 wt % of BHIP is used, blocking of the film becomes somewhat worse.

The crystalline polypropylene B used in the present invention is a homopolymer of propylene or a random copolymer of propylene with other α-olefins such as ethylene, butene-1, hexene-1,4 methyl-pentene-1, etc. (Two or more types may be used in combination.) However, the cold xylene soluble portion is (
CXS) is 15 wt% or less, and further,
The α-olefin content is 10 mol% or less.

In the present invention, the blend ratio of copolymer A and crystalline polypropylene B is 80 to 95 w.
Preferably, the amount of copolymer A is 40 to 95 wt%, and the amount of crystalline polypropylene B is 60 to 5 wt%. If the blend ratio of copolymer A is below the lower limit, it is difficult to achieve both flexibility, excellent transparency, and glossiness of the film, and a film with a uniform thickness distribution cannot be obtained by stretching at a low stretching ratio. This is undesirable because it results in a film with poor tear strength and poor tear strength.

Copolymer A and crystalline polypropylene B used in the present invention
A blend composition can be obtained by uniformly dispersing it by any known method. For example, extrusion melt blending,
Examples include the Banbury blend method.

Copolymer A and crystalline polypropylene B used in the present invention
The flexural modulus of the blend composition with
It is preferably a, ooo to 6,000 deception. If the flexural modulus of the blend composition is below the lower limit, the film will be too soft and will tend to shrink over time, and the tear strength and blocking resistance will deteriorate, which is undesirable (if the flexural modulus is below the upper limit If it exceeds this, the flexibility of the film will be lost, and if the stretching ratio is low, it will be difficult to obtain a film with a uniform thickness distribution, and the tear strength will also be poor, which is not preferable.

Small amounts of other polymeric materials can also be blended into the blend compositions used in the present invention.

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-cooled inflation method can be employed as a method for forming the blend composition into a film. Also at least 1
As a method for stretching in the direction, known uniaxial stretching methods such as roll stretching and roll rolling, as well as known biaxial stretching methods such as flat biaxial stretching and Cheveler biaxial stretching, can be used. Stretching is preferable because a well-balanced film can be obtained. The blend composition of the present invention has the characteristic that low-magnification stretching can be performed satisfactorily even in the flat biaxial stretching method, in which it is generally difficult to obtain a uniform thickness distribution with low-magnification stretching. The stretching temperature is from room temperature to below the melting point of the blend composition, and is from 100 to 180°C.
is preferred. The stretching ratio is 1.2 to 5 times, and 1.
3 to 4 times is preferable, and 1.5 to 8 times is more preferable. If the stretching ratio exceeds the upper limit, the tear strength of the film will be unfavorable even if the above properties of the copolymer are within the specified range, and if the stretching ratio falls below the lower limit, the film will lack strength. Undesirable. In addition, in order to increase the effect of preventing film shrinkage over time, heat setting (
Annealing) is recommended. The heat setting is preferably carried out at a temperature of (stretching temperature -10) C or higher, more preferably at a temperature of 110''C or higher.

Regarding the physical properties of the film thus obtained, the tear strength is preferably 7 g or more, preferably 109 or more, and more preferably 15 f or more. If the tear strength is below the lower limit, it is undesirable because it is likely to be torn from the hooked portion. Also, the Young's modulus of MD and TD is 2.
Preferably between 000 and 7,000 secrets, 2,0
00 to 6,000 by- is more preferable.

If the Young's modulus of the film is below the lower limit, it will be too soft compared to vinylon film, which is undesirable.
If the upper limit is exceeded, the flexibility of vinylon film will be lost, which is not preferable.

Also, the strength at break in at least one direction of the film is 400
Kl/cIIi or higher is preferred. If this strength is less than 400 degrees, the hook resistance (as the hook of the bag is opened and closed many times, the film stretches in the opening/closing direction and loses its commercial value) is undesirable. The shrinkage rate of a propylene film generally increases as the Young's modulus is smaller, but according to the method of the present inventors, it is possible to provide a film with a smaller 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 (Y) at 100''C.

%) and Young's modulus (X, b/cd) satisfies the following inequality.

Y<50-0.0085X Further, it is preferable that the following inequality (1) be satisfied.

Y<85-0.002X If the shrinkage rate of the film is large, the summer film will gradually shrink over time and wrinkles will occur during fusing and sealing, resulting in poor practical value. Therefore, the present invention provides an excellent film that is 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 very similar to that of vinylon film, and can also be processed with hooks, without the drawbacks of vinylon film. 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 determined by a conventional method using an infrared spectrophotometer from the characteristic absorption at 770α, and the mass balance results were confirmed. In addition, in the measurement using an infrared spectrophotometer, 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
The mass balance results were confirmed by quantification using a conventional method from the characteristic absorption at 82 and 720 cm-'. In addition, in the measurement using an infrared spectrophotometer, a test t* was prepared and quantified based on the quantitative value obtained by radiation measurement of 14C-labeled ethylene copolymer.

(8) Cold xylene soluble portion (CXS) Polymer 61 is dissolved in xylene 500- and then slowly cooled to room temperature.

Then, it was left in a bath at 20"C for 4 hours, filtered, and the filtrate was concentrated, dried, and weighed.

(4) Intrinsic viscosity ([η]) Tetralin IJ at 15°C with a concentration of 0.4 and 0
．． The measurement was performed at four different points: 2, 0.188, and 0.11/dt.

(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-D790.

However, sample shape: 2wt×2G-width×50IllI
Distance between long spans: 80m5+ Deformation speed: 1/min (7) Young's modulus of film Complies with ASTM-D882.

However, test piece shape: 20 x 120 rectangular chuck distance = 501 Tensile speed: 5 / min (8) Tensile properties of film conform to ASTM-D882.

However, tensile speed = 200 so/min (9) Haze value Compliant with ASTM-Dl 008.

qΦ Gross Compliant with ASTM-D52B.

(lυ tear strength Conforms to JIS K6772.

@ Blocking Two films are overlapped and the area is #7 per 100-
Condition the film at 28"C for 24 hours while applying a load of Expressed in terms of 100 cd of film area.

(To) Shrinkage rate: Shown as the dimensional change rate when immersed in a glycerin bath at 100°C for 80 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) 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, 88 mm of n-hebutane, 16.1 Wlt of titanium tetrachloride, and 16.1 Wlt of titanium tetrachloride were added. -Butoxytitanium 51.0- was charged into the flask, and the temperature inside the flask was maintained at 20°C while stirring. n-hebutane 162
, 1- and diethylaluminium chloride 87.8- was gradually added dropwise from the dropping funnel over 8 hours while maintaining the temperature inside the flask at 20°C. 5 after completion of dripping
The temperature was raised to 0°C and stirred for 1 hour. The mixture was allowed to stand at room temperature for solid-liquid separation, washed four times with 200 m of n-hebutane, and then dried under reduced pressure to obtain 64.71 of a reddish-brown solid product.

(2) Synthesis of prepolymerized solid After purging an 800 d flask equipped with a stirrer with argon, the solid product prepared in (A) above 19. Tf was charged into the flask and the temperature was maintained at 50°C. Next, while stirring, ethylene was added at a partial pressure of 0.2 Kp/
The mixture was gradually fed into the suspension at 50° C. for 20 minutes while maintaining the temperature at cd, and prepolymerization was performed. After treatment, solid-liquid separation,
After repeating washing twice with 50% of n-hebutane, it was dried under reduced pressure. The amount of prepolymerization is 0 polymer per 1f of solid product.
．． It was 091.

(8) Synthesis of solid catalyst component After purging a flask with an internal volume of 100 mm with argon, 12.11 of the prepolymerized solid prepared in CB) and 42.8 of n-hebutane were put into the flask. The temperature was kept at 80°C. Next, di-iso-amyl ether 14.4- was added and treated at 80°C for 1 hour.
The temperature was raised to 6"C. At 75°C, 15°7" of titanium tetrachloride was added. The reaction was carried out at 75"C for 1 hour. After solid-liquid separation, washing was repeated 4 times with 50wt of n-hebutane. Afterwards, it was dried under reduced pressure to obtain a solid component.Furthermore, after purging the flask with an internal volume of 100 cm with argon, 9.9 f of the above solid component was obtained.
and n-hebutane 88- were charged into the flask, and the temperature inside the flask was maintained at 80°C.

Next, 8.5 wj of di-iso-amyl ether was added, the mixture was treated at 80°C for 1 hour, and then the temperature was raised to 75°C. 7
11.5- titanium tetrachloride was added at 5"C, and the reaction was carried out at 75°C for 1 hour. After solid-liquid separation, washing was repeated four times with n-hebutane 5o-, and the solid catalyst component was dried under reduced pressure. I got it.

(4) Copolymerization A 100-ton autoclave is equipped with a stirrer, a thermometer, a dropping funnel, and a reflux condenser, and the pressure is reduced, and then replaced with nitrogen.

5 t of normal hexane dried in this autoclave
was kept at a constant temperature of 50°C, and a mixed gas of 71 mol% propylene and 129 mol% butene was added at 0.28 N.
d Flow at a rate of 1 minute. Then, 80 f of diethylaluminium chloride and 1.65 g of C-caprolactone were used as catalysts.
jF and further the solid catalyst 8 obtained in the above (8)
Add f to start polymerization. Polymerization was carried out by continuously flowing a mixed gas of propylene and butene-1 for 120 minutes while stirring. Next, 1.5 t of butanol was added to stop the reaction, and after washing thoroughly with butanol, the reaction product was poured into a large amount of methanol to precipitate a copolymer. The intrinsic viscosity of this copolymer was 2.2 dL/f, the butene-1 content was 26.5 mol%, and the CxS was 56 wt.
%, the flexural modulus is 2200 Kl/m, and △
Haze was 8.5%.

(5) Blend Copolymer 5 Q wt% obtained in the above (4) and propylene ethylene random copolymer (ethylene content 5.8 mol%, milt index 7f/10 min) as crystalline polypropylene-B. ) and 50 wt% were blended using a melt extruder.

The flexural modulus of the resulting composition was 4,800 Kg/d.

(6) Film molding This composition was molded to a thickness of 270 μm under the following molding conditions.
A raw film was obtained.

Extruder: Manufactured by Egan 65m12j Extruder Screw: Single full flight type, L/D=24
.

C, R, = 4.0 Temperature condition: 280℃ Die: Coat hanger die, Ritsu degree 0.
9 m, width 600 mm Molding speed = 8 m/min This original film was stretched as follows to obtain a biaxially stretched film having a thickness of 80 μm. The physical properties of the film are shown in Table 1.

Stretching machine: Tenter biaxial stretching machine (made by Nippon Steel) Stretching conditions: Entry side Line speed 8m/min Output side
9m/min MD stretching ratio: 8x TD stretching ratio: 8x Temperature conditions: MD stretching 120°C TD Preheating zone 120°C Stretching zone 120”C Annealing zone 120°C This biaxially stretched film is flexible, has excellent transparency, and gloss. ,
In addition, the film has sufficient tensile strength to enable hook attachment in both MD and TD directions, and tear strength sufficient to withstand tearing from the hook part, and there is no risk of gradual shrinkage over time. there were.

Comparative Example 1 A biaxially stretched film was obtained from the composition used in Example 1 under the same conditions as in Example 1 except that the stretching ratio was changed to 2 times Mn 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 indicates that even if the composition meets the spirit of the present invention, a good film cannot be obtained unless the stretching ratio falls within the range of the spirit of the present invention.

Comparative Example 2 A biaxially stretched film was obtained from the copolymer obtained in Example 1 (4) 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., it becomes difficult to adhere to the line.) The physical properties of the film are shown in Table 1. This film has extremely high blocking of 10 (1'/100- or more).
(The film of the example had a value of 20 g/IQOeI11 or less.) The tear strength was not so good, and it also shrunk over time in summer, so it was not a film that could be used practically.

Comparative Example 8 20 wt% of copolymer A obtained in (4) of Example 1,
Crystalline polypropylene B f3 Q used in Example 1
wt% and blended using a melt extruder.

The flexural modulus of the resulting composition was 7200 v-.

A biaxially stretched film was obtained from this composition under the same stretching conditions as in Example 1 except that the temperature condition was changed to 125°C.

However, the obtained film had a considerably poor thickness distribution in the TD force direction compared to the example. Film properties first
Shown in the table. This film had poor flexibility, and its transparency, gloss, and tear strength were not very good.

Example 2 (1) Preparation of a solid catalyst containing titanium trichloride After purging a flask with a capacity of 1/4 inch equipped with a stirrer and a dropping funnel with argon, titanium tetrachloride 60- and n-hebutane 228-
Ethylaluminum sesquichloride 18 in a solution consisting of
A solution consisting of 6.6d and 800m of n-hebutane was heated to -5
It was added dropwise at ~-10''C for 2 hours.

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

Next, 580 m of n-hebutane and 5 m of diethylaluminum chloride were charged into the flask, and the temperature was maintained at 50°C. While stirring, propylene 829 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% n-hebutane.

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
Add 7m and tri-n-octylamine 8.7-;
The reaction was carried out at 85°C for 15 minutes. After the reaction, a solution of iodine 15.5F dissolved in toluene 196m was added, and
The reaction was carried out at ℃ for 45 minutes.

After the reaction, solid-liquid separation was performed, washed once with 500 m of toluene and 8 times with 500 m of n-hebutane, and then dried under reduced pressure to obtain titanium trichloride-containing solid catalyst 90f. Titanium trichloride is 65.2% by weight in the titanium trichloride-containing solid catalyst.
It was contained.

(2) Propylene and butene-1 were copolymerized using a fluidized bed reactor equipped with a stirrer and having a copolymerization internal volume of 1-1. First, 6 pieces of propylene-butene-1 copolymer particles for catalyst dispersion were placed in the reactor.
The reactor was then purged with nitrogen and then with propylene. The pressure was increased to 5 h/ct/IG with propylene, and circulating gas was supplied from the bottom of the reactor with a flow rate of 80 ff//hr to keep the polymer particles in a fluid state, and then the following catalyst was supplied to the reactor. . Catalyst component (B), (C
) used a solution diluted with hebutane.

(a) Solid catalyst containing titanium trichloride 211(b)
Diethylaluminium chloride 112f (C) Triethylaluminum 1lf (d) Methyl methacrylate 8F, then hydrogen concentration 1.7vol
%, butene-12Q vol. Hydrogen, propylene, and butene-1 were supplied and the pressure was increased to 6 toicp751G, and the temperature of the fluidized bed was adjusted to 65° C. to start polymerization. During the polymerization, hydrogen, propylene, and butene-1 were supplied so as to keep the concentration and pressure of hydrogen ζ-butene-1 constant.

When the amount of polymerization reached 75 KII, the polymer particles were left in the reactor for catalyst dispersion in the next polymerization, and the remaining polymer particles were transferred to a stirring mixing tank, and 210 f of propylene oxide and 100 f of methanol were added. 8 at 80℃
Processed for 0 minutes. It was then dried to obtain a white powdery polymer. The same polymerization was repeated eight times, and the physical properties of the finally obtained polymer were measured. Butene-1 content of this copolymer was 17.8 wt, JL'15, CX5j, t29.6wt
%, intrinsic viscosity number is 10g dt7y, bending modulus is 4
100Kf/cIIi, ΔHaze was 2.0%.

(8) Blend 8Q wt% of copolymer A obtained in (2) above and 120 wt% of crystalline polypropylene B used in Example 1
Both were blended using a melt extruder.

The flexural modulus of the resulting composition was 5,000 Kg/a
It was A.

(4) Film forming A biaxially stretched film was obtained from this composition under the same conditions as those shown in Example 1. This film was as good as the film obtained in Example 1.

6. Contents of correction Procedural amendment (voluntary) April 9, 1986

Claims (1)

[Scope of Claims] (1) A copolymer of propylene and an α-olefin having at least several carbon layers, or a copolymer of propylene, an α-olefin having at least several carbon layers, and ethylene under the following conditions [1] to [3] [ 1] The content of α-olefin having 4 or more carbon atoms in the copolymer is 8 to 35 mol%. [2] The ethylene content of the copolymer is 5 mol% or less. [3] The cold xylene soluble portion of the copolymer is At least a resin composition having a flexural modulus of 2,500 to 6,500 Kg/cm^2, which is a blend of 30 to 95 wt% of copolymer A satisfying 15 to 80 wt% and 70 to 5 wt% of crystalline polypropylene B, A packaging film that is stretched in 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. (8) Young's modulus in MD and TD direction is 2000-700
0 Kg/cm^2 and a strength at break 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 8, 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 ΔHaze of copolymer A is 7% or less. (6) The packaging film according to claim 1, 2, 3, 4, or 5, wherein the α-olefin having 4 or more carbon atoms in copolymer A is butene-1. (7) Claims 1, 2, 3, 4, 5, or 6 which are subjected to a stretching process with a stretching ratio of 1.2 to 5 times. packaging film. (8) Claims (1), (2), (3), (4), (5), and (6) obtained by subjecting the stretching process to biaxial stretching.
Or the packaging film described in item 7.