JP2022516615A - Polymers for high speed production of biaxially stretched films, films and articles produced from them - Google Patents

Abstract

The present invention relates to films, particularly polypropylene for producing biaxially stretched polypropylene (BOPP) films. The patented structural properties of polypropylene allow for increased process speeds (450 m / min and above) in the BOPP film manufacturing process. The present invention also provides a BOPP film in which at least one layer contains polypropylene. The film according to the present invention can be used for food packaging, adhesive tapes, labels and the like.

Description

The present invention relates to films, especially polypropylenes for preparing biaxially stretched polypropylene (BOPP) films. Due to the structural properties of the claimed polypropylene, the process speed of preparing the BOPP film is 450 m / m / without the use of slip additives (eg, metal stearate) known to facilitate the film manufacturing process. It can be increased to more than a minute. The present invention also relates to BOPP films in which at least one layer contains polypropylene. The films according to the invention are suitable for producing packaging including food packaging, adhesive tapes, labels and the like.

Polypropylene film is a common material for producing high quality flexible packaging because its properties may vary depending on its composition and manufacturing method. In particular, biaxially oriented polypropylene (BOPP) films are used in the manufacture of packaging for food and non-food products, individual or multi-unit packaging. Here, these packages can be made transparent, metallized, matted, or colored (depending on the color of the filler). In addition, BOPP films are used in the manufacture of labels, adhesive tapes and the like.

In principle, the main component of the BOPP film is isotactic polypropylene with 87-89% isotacticity ⁽ isotacticity is isotactic pentad [mmmm] by C13 NMR analysis]. It is determined by the fraction.) The presence of a certain number of defects in the structure of the isotactic polymer contributes to the higher orientation ability of the polymer. The higher orientation capacity of polypropylene, in turn, makes it possible to increase the process speed and increase film production.

Heat resistant films are known from European Patent No. 2143116. At least one layer of the film is subjected to a melt flow rate of 0.5 to 15 g / 10 min and a cold xylene soluble fraction of less than 3.5 mass%; by X-ray diffraction in the range of 0.5 to 0.85. Contains polypropylene with a determined crystallinity and a xylene and heptane insoluble fraction content of greater than 94% by weight. The film further comprises at least a second layer containing a heterogeneous statistical copolymer (impact copolymer), the heterophase statistical copolymer having a melt flow rate of 0.5-15.0 g / 10 min and a melt flow rate of 0.5-15.0 g / 10 min. It has a melting point of 120-170 ° C. This film is characterized by high tear strength, impact strength, and puncture resistance due to the low content of the cold xylene soluble (XCS) fraction. The drawback of this solution proposed in European Patent No. 2143116 is the slow process rate of polypropylene due to the low content of the cold xylene soluble fraction.

High metal adhesive films and metallized films are known from European Patent No. 0925912. The core layer is made of isotactic polypropylene having an isotactic pentad [mmmm] fraction of 88% or more, preferably 90% or more, and a Mw / Mn range of 2-6. However, at the same time, other properties of isotactic polypropylene (contents of fractions having a specific molecular weight and fractions soluble in xylene and heptane) are not disclosed. The process speed has not been specified either.

Further, from European Patent No. 0831994, a method for producing a BOPP film is known. The core layer of this film contains polypropylene with a degree of at least 10% or less than 5% with an isotactic polymer and an atactic polypropylene, syndiotactic polypropylene, ethylene-propylene copolymer. , A propylene terpolymer, a polybutene, or a polymer composition comprising a mixture with a linear low density polyethylene polymer. By using a polypropylene or polymer composition having a degree of aggression of 10% or more, a BOPP film having a high tear resistance can be obtained. There are no other requirements for the properties of isotactic polypropylene. Therefore, the content of fractions with a particular molecular weight and fractions with a particular solubility in xylene and heptane is seen as an important indicator for determining the suitability of polypropylene for use in the film processing process. Not done.

Therefore, the structural properties of polypropylene for use in the manufacture of BOPP films that allow processing at a speed of at least 450 m / min while maintaining the required degree of film strength properties according to regulatory documentation. The perfect combination of is not yet known.

European Patent No. 2143116 European Patent No. 0925912 European Patent No. 0831994

It is an object of the present invention to determine a combination of structural properties of polypropylene that makes it possible to increase the efficiency of the polypropylene stretching (biaxial orientation) process to obtain a BOPP film.

The technical result of the present invention is polypropylene, a BOPP film by using polypropylene in the film composition, which, due to its structural properties, allows the film to be processed at a rate of at least 450 m / min. It is to improve the productivity of the process to obtain.

Further technical consequences are the possibility of obtaining a wide range of films such as transparent, matte, filled, general purpose, and the application of layered coatings such as metallized layers, printing.

The subject of the present invention is polypropylene, which has the following characteristics:
-The amount of the cold xylene soluble fraction (XCS) is in the range of 2.5 to 4.0% by mass, and here, the molecular weight of the cold xylene soluble fraction is mainly 1,500 to 50,000 g / g. The proportion of fractions with a molecular weight above 50,000 g / mol, while within the molar range, does not exceed 30% by weight; and-the amount of heptane-soluble fraction (HS) in the polymer is 2. The proportion of the polymer having a molecular weight of 400,000 to 3,000,000 g / mol, which is in the range of 5 to 3.5% by mass, is 10% by mass or less, and 1,500 to 1,500 to The proportion of components having a molecular weight of 50,000 g / mol was solved by introducing polypropylene having at least 60% by weight into the film and the technical results were achieved.

We found that the specific content of the xylene-soluble and heptane-soluble fractions, characterized by specific molecular weight values, increased the process rate of obtaining biaxially stretched films by improving the orientation of polypropylene. I found it possible. Without wishing to be bound by any particular theory, we have a high molecular weight (1,500-0000 g / mol) high content (60% by weight or more) of the heptane-soluble fraction. , Polymer It is believed to improve the orientation of the polymer during the processing process and then increase the process speed up to 450 m / min or more.

The following is a detailed description of various aspects and embodiments of the present invention.

Polypropylene, which will be used in the preparation of films, has the following properties:
-The content of the cold xylene-soluble fraction (hereinafter referred to as "XCS") is in the range of 2.5 to 4.0% by mass, preferably in the range of 3.0 to 3.8% by mass. That; and-the content of the heptane-soluble fraction (hereinafter referred to as "HS") is characterized by being in the range of 2.5 to 3.5% by mass.

The unique properties of polypropylene described in the claims that will be used in the manufacture of BOPP films are 50, whereas the molecular weight of the XCS fraction is primarily in the range of 1,500 to 50,000 g / mol. The amount of the XCS fraction having a molecular weight of more than 1,000 g / mol does not exceed 30% by weight, preferably no more than 15% by weight, more preferably no more than 5% by weight.

Another essential property of polypropylene described in the scope of patent claims used in the manufacture of BOPP films is that the proportion of HS fractions with a molecular weight of 400,000 to 3,000,000 g / mol does not exceed 10% by weight. The proportion of the HS fraction having a molecular weight of 1,500 to 50,000 g / mol is at least 60% by weight, preferably at least 5% by weight, preferably not more than 7% by weight, most preferably not more than 5% by weight. 70% by weight, most preferably at least 75% by weight.

When the amount of the heptane-soluble fraction is less than 2.5% by weight, or at the total content of the HS fraction within the specified range of 2.5 to 3.5% by weight, the composition of the HS fraction is: The proportion of low molecular weight (molecular weight 1,500 to 50,000 g / mol) component decreases, and / or the proportion of high molecular weight (molecular weight 400,000 to 3,000,000 g / mol) component increases. In some cases, the result is a decrease in the processability of the polymer.

An amount of heptane-soluble fraction above 3.5% by weight results in a decrease in the physico-mechanical properties of the film as well as an increase in carbon formation on the spinneret during the processing process.

The processability of the film and its properties are also affected by changes in the amount and composition of the XCS fraction.

Therefore, if the amount of the XCS fraction is less than 2.5% by weight, the processability of the film is reduced, which reduces the polymer orientation ability of the polymer used, regardless of its molecular weight characteristics. caused by.

When a polymer having an XCS fraction in an amount of more than 4.0% by mass is used in the preparation of the film, its physical mechanical properties are deteriorated, and the polymer-to-film process is carried out onto the spun cap. Increased formation of carbon deposits is observed.

Preferably, the polypropylene has a molecular weight distribution of 5 to 7, more preferably 6 to 7.

Preferably, the content of the isotactic [mmmm] fraction of the polymer is 87-89%.

The present invention provides a polymer for preparing BOPP films at high process rates (at least 450 m / min), which is a supported Ziegler-Natta titanium of the general formula MgCl ₂ / TiCl ₄ / D ₁ / D ₂ /. -Can be obtained using a magnesium catalyst. In the formula, titanium tetrahalogenated is supported on magnesium halide, D ₁ is an internal electron donor, D ₂ is an external electron donor, and triethylaluminum (TEA) is a cocatalyst. In particular, D ₁ can be selected from the following compounds:

Group of Alcohols: Preferred alcohols are compounds of the formula R ¹ OH, where the R ¹ group represents _a C1-C ₂₀ hydrocarbon group. In a more preferred embodiment, R ¹ is a C ₁ to C ₂₀ alkyl group. Specific examples are methanol, ethanol, isopropanol, and butanol.

Group of Amines: Preferred amines _are compounds of formula NR 23, where the ^R2 groups are independent of ^each other, hydrogen or C1 _- C ₂₀ hydrocarbon groups, but not all at the same time. .. In a more preferred embodiment, R ² is a C ₁ to C ₂₀ alkyl group. Specific examples are diethylamine, diisopropylamine, and triethylamine.

Group of amides: Preferred amides are represented by the formula R ³ CONR ^{42, in which R 3} _and R ⁴ are independent of ^each other, hydrogen or C1 _- C ₂₀ hydrocarbon groups. Specific examples are formamide and acetamide.

Group of Esters: Preferred esters are aromatic carboxylic acid monoesters such as benzoic acid esters, especially aliphatic carboxylic acid monoesters such as benzoic acid C1 _- C ₂₀ alkyl, eg C1 _- C of aliphatic monocarboxylic acids. It can be selected from ₈ alkyl esters and the like, and 1,8-naphthyldiesters.

Another group is the C1 _- C ₂₀ alkyl esters of aromatic dicarboxylic acids, such as phthalates, and the C1 _- C ₂₀ alkyl esters of aliphatic dicarboxylic acids, such as malonic acid esters, succinic acid esters, glutarates. Etc. are included. In addition, diol diesters can also be used.

As D ₂ , an organosilicon compound represented by the following formula: R _n Si (OR) _4-n can be used. In the formula, R is a hydrocarbon radical, OR is an alkoxy group, R is a hydrocarbon group, and n is an integer of 0 <n <4. Examples of organic silicon compounds represented by this formula that can be used in the present invention include: diisopropyldimethoxysilane, tert-butylmethyldimethoxysilane, tert-butylmethyldiethoxysilane, tert-amylmethyldi. Ethoxysilane, dicyclohexyldimethoxysilane, cyclohexylmethyldimethoxysilane, cyclohexylmethyldiethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, tert-butyltriethoxysilane, phenyltriethoxysilane, cyclohexyltrimethoxysilane, cyclopentyltrimethoxysilane, 2-Methylcyclopentyl trimethoxysilane, cyclopentyl tiltriethoxysilane, n-propyltrimethoxysilane, dicyclopentyldimethoxysilane, dicyclopentyldiethoxysilane, tricyclopentylmethoxysilane, dicyclopentylmethylmethoxysilane, dicyclopentylethylmethoxysilane, and cyclopentyl Dimethylethoxysilane.

More specific examples of the described catalysts and methods thereof are disclosed in European Patent No. 2221320, European Patent No. 2638080, and European Patent No. 2951215.

The polypropylene of the present invention can be obtained by vapor phase or suspension polymerization of propylene in the presence of the catalyst described above. In any of the polymerization methods used, the components of the catalytic system (catalysts, co-catalysts, and optionally external electron donors) can be brought into contact with each other prior to their addition to the polymerization reactor. As the co-catalyst, alkyl-Al compounds such as triethylaluminum, diethylaluminum chloride, triisobutylaluminum, tri-n-butylaluminum, tri-n-hexylamine aluminum, tri-n-octylaluminum and the like can be used. ..

Polymerization using a Ziegler-Natta catalyst generally has a temperature in the range of 50-80 ° C, preferably in the range of 65-75 ° C, and a range of 0.1-5.0 MPa, preferably 0.5-3.5 MPa. It is carried out with an operating pressure in the range of.

Preferably, the melt flow index (MFI _{230 ° C./2.16 kg} ) of the polymer used, as determined in accordance with ASTM D 1238, to maintain the physico-mechanical properties of the produced film, is at least 3 g. Should be / 10 minutes.

In particular, polypropylene can be prepared, for example, according to the methods described in US Pat. No. 8,178,633, European Patent No. 2726517, and the like.

These methods of producing polypropylene, given as an example, allow the achievement of the above properties, but are not limited to these methods. Polypropylene with the specified properties can be obtained by other methods known from the prior art.

Preferably, polypropylene comprises a stabilizer containing at least a mixture of antioxidants and acid absorbers. Any antioxidant known from the prior art can be used as the antioxidant, preferably a mixture of a phosphite ester antioxidant and a phenol antioxidant. As the acid absorber, any acid absorber known from the prior art can be used, except for absorbents from the metal stearate class. In addition, other known additives can be further used to allow polypropylene to retain its properties during process and operation. The amount of the stabilizer added to polypropylene is 1 to 3 kg per ton of polypropylene, preferably 1.2 to 2.5 kg per ton of polypropylene, and more preferably 1.2 to 1.5 kg per ton of polypropylene.

The polypropylene according to the present invention is substantially free of calcium stearate. Calcium stearate is converted to stearic acid when it interacts with the acid. Stearic acid easily migrates to the surface of the film, making it impossible to make metallized films. The expression "substantially free" means a content of less than 0.010% by weight, preferably less than 0.005% by weight, most preferably less than 0.001% by weight.

The identified polypropylene can be used as a major component or as an additional component of any film layer of any formulation known from the prior art. The exact structure of the film (number and order of layers) and the contents of the layers depend on the requirements of the film and the products made from it.

In addition to the polypropylenes of the invention, the film may contain other polyolefins as well as functional polymers. α-Olefin copolymers and terpolymers, specifically propylene and ethylene copolymers, propylene and butene copolymers, propylene, ethylene and butene terpolymers and the like are used as polyolefins. The following compounds are used as functional polymers: ethylene and vinyl alcohol copolymers, polyvinylidene chloride, vinylidene chloride copolymers, polyesters, polyamides (to confer gas and / or deodorant properties on films), ethylene and α-Olefin interpolymer (for paper-film lamination without adhesive), homopolypropylene anhydride maleate (adhesive layer in co-extruded film), etc.

In the first embodiment of the present invention, the film is intended for producing a wrapping paper as a base for an adhesive tape or the like, and polypropylene having each layer having the above-mentioned characteristics, an antistatic substance and / or an anti-caking substance and / Alternatively, it is a multilayer polypropylene film made of an antioxidant. The antiblocking agent is silicon dioxide (SiO ₂ ), polymethylmethacrylate (PMMA) or the like, and the antioxidant is a phenolic antioxidant.

In a second embodiment of the invention, the film is intended for adhesive-free film-paper lamination, including at least the following: a polymer-containing core layer having the above-mentioned properties, and: Functionalized layers containing: ethylene-butene copolymer, ethylene-octene copolymer, ethylene-butene-octentapolymer, ethylene-butene copolymer modified with grafted maleic acid anhydride, ethylene modified with grafted maleic acid anhydride -Formed from any of the octene copolymers, ethylene-butene-octenter polymers modified with grafted maleic anhydride, or mixtures thereof, or the listed copolymers and / or terpolymers, modified copolymers and / or terpolymers. Blended with the polymerized mixture, as well as the polymerized petroleum resin.

In a third embodiment of the invention, the film is a barrier film and comprises at least the following layers: represented by one layer of propylene polymer having the above-mentioned properties, and copolymers of polyamides, ethylene and vinyl alcohols and the like. A layer of gas barrier material. A layer of modified polyolefin, for example a layer of propylene polymer modified with maleic anhydride, can optionally be used to improve the adhesion between the layer of propylene polymer and the layer of gas barrier material that meet the above properties. ..

Other embodiments of the invention will be apparent to those of skill in the art and will not be disclosed in detail in the description of the invention. For example, the additive can be included in the formulation in an effective amount, i.e., in an amount that provides the desired functional properties or improves the parameters and / or functionality of the final film. In particular, examples of additives include, but are not limited to: additives that provide anti-caking, antistatic, and slipping effects, as well as antioxidants and neutralizers, technical additives, Nuclear agents, additives that reduce the effects of UV irradiation, UV absorbers, dyes, fillers, thickeners, hydrocarbon resin-based modifiers, etc.

The total thickness of the film varies over a wide range depending on its intended use. In a preferred embodiment, the film has a total thickness of 2-100 μm, preferably 5-50 μm, more preferably 10-30 μm.
The film of the present invention is obtained by co-extruding polypropylene with other polymers and then stretching. The orientation value of the film in the mechanical direction is 4.5 to 5.5, and the maximum is 10 in the horizontal direction.

The film prepared according to the present invention after stretching can be processed by the following procedure.
1. 1. Emboss the surface of the film.
2. 2. The surface of the film is activated / modified (eg by plasma treatment, corona treatment, flame treatment) to make it suitable for printing.
3. 3. The prepared film is laminated onto a woven or non-woven material, especially paper, foil or other film.
4. Metal layer deposition (eg, aluminum layer deposition by vacuum technology based on the condensation of metal vapors).
5. An adhesive layer is applied on one or both sides of the film to obtain an adhesive film.

Optionally, the treated film is used to produce final products such as packaging, metallized packaging, labels, bags, adhesive tapes and other articles using the BOPP film according to the invention. Specific examples include the creation of labels specified in European Patent No. 2197669, International Publication No. 2017/077184, in particular the creation of bags disclosed in US Pat. No. 9,108,391, such as International Publication No. 2016 /. Includes, but is not limited to, the manufacture of food packaging as shown in 205381, and the manufacture of metallized films as described in European Patent No. 0925912.

[Test method]:
1. 1. Meltflow index (MFI) was measured according to ASTMD1238.
2. 2. The mass fraction of the soluble fraction in the boiling heptane / isotactic fraction was measured according to the National State Standard 26996-86.
3. 3. The mass fraction of the fraction soluble in xylene was measured according to ISO 16152.
4. Measurement of the molecular weight distribution (MWD) of polypropylene samples and statistical copolymer samples of propylene and ethylene is ISO 16014-4-2012: Gel Permeation Chromatography (GPC) on the Agent PL-GPC 220 system according to the high temperature method. Went by. The dissolution temperature was 150 ° C. and the solvent was 1,2,4-trichlorobenzene.
5. Measurement of the molecular weight properties of xylene-soluble (XCS) and heptane-soluble (HS) substances from the sample is performed by the low-temperature GPC method using an Agilent 1200 liquid chromatograph (manufactured by Agilent) based on the ISO16014-4-2012: low-temperature method. rice field. The measured dissolution temperature was 40 ° C. and the solvent was tetrahydrofuran.
6. The microstructure, isotacticity, and pentad ratio of the polypropylene sample were determined by high resolution nuclear magnetic resonance spectroscopy ( ¹³ C NMR) of the carbon nuclei on a Bruker Availability III 400 MHz NMR spectrometer. For research purposes, 250 μg of sample was dissolved in 2.5 ml of trichlorobenzene while heating to 140 ° C. ¹³ С The number of nuclear scans is 16,000. The measurement temperature was 140 ° C.

The present invention will be described in more detail with reference to the following examples. It provides an example for explaining the present invention, and does not limit the scope thereof.

[Example 1]
Propylene polymers with an MFI of 3.0 g / 10 min (230 ° C. and 2.16 kg) were obtained by vapor phase technology at a temperature of 65-75 ° C. and an operating pressure of 2.2 MPa. As the catalyst, a catalyst prepared in the same manner as in Example 1 of US Pat. No. 9,284,392 was used, except that diisobutyldimethoxysilane was used as an external electron donor.

The BOPP film is a five-layer film, each of which is made of the above-mentioned polypropylene and an antioxidant [for example, pentaerythritol tetraoxy (3- (3,5-di-tert-butyl-), which is a hindered phenolic antioxidant). 4-Hydroxyphenyl) propionate) (Irganox 1010) and tris (2,4-di-tert-butylphenyl) phosphite (Irgafos 168), which is a phosphorus-containing antioxidant, and hydrotalcite as an acid absorber. Is included in an amount of 1.35 kg of stabilizer per ton of polypropylene. Films were prepared by continuous extrusion of polypropylene, stepwise orientation, thermosetting, and cooling of the film slab. The molten material plasticized in each extruder (five extruders corresponding to the number of layers) is combined with a die (head), and the confluent is flowed from the slot die to the cooling drum (shaft) in the form of a slab, and then. The slab was cooled by passing it through a water bath. The film slab was then reheated on a heating cylinder to 100-115 ° C. and stretched on a roller in the mechanical direction to 6 times its original length. The film stretched in the mechanical direction was placed in an oven, heated again with air to a maximum of 170-180 ° C., and stretched laterally to 10 times the original width. The total film thickness was 20 μm, the outer layer was 0.9 μm, the intermediate layer was 2.5 μm, and the core layer was 13.2 μm. Table 1 shows the characteristics of the polypropylene used and the process speed of the film.

[Example 2]
BOPP films were prepared in the same manner as in Example 1 except that polypropylene had the properties shown in Table 1. The process speed of the film is shown in Table 1.

[Example 3]
The BOPP film was prepared in the same manner as in Example 1 except that polypropylene having the properties shown in Table 1 was used. The process speed of the film is shown in Table 1.

[Example 4 (comparison)]
The BOPP film is made of polypropylene obtained using a Ziegler-Natta catalyst containing an internal electron donor such as dibutyl phthalate (described in European Patent No. 0193281), and the properties of which polypropylene is shown in Table 1. It was prepared in the same manner as in Example 1 except that it had. The process speed of the film is shown in Table 1.

[Example 5 (comparison)]
BOPP film is made of polypropylene obtained using a Ziegler-Natta catalyst containing an internal electron donor such as 9,9-bis-methoxymethyl-fluorene (described in US Pat. No. 8,003559), and the like. It was prepared in the same manner as in Example 1 except that polypropylene has the properties shown in Table 1. The process speed of the film is shown in Table 1.

[Example 6 (comparison)]
BOPP film is obtained using a Ziegler-Natta catalyst containing a multi-component internal electron donor such as (3,3-bis (methoxymethyl) -2,6-dimethylheptane and 2,3-diisopropylsuccinate diethyl). BOPP films were prepared in the same manner as in Example 1 except that the polypropylene (described in US Patent Application Publication No. 2016/0102159) was used and that the polypropylene had the properties shown in Table 1. The process speed of the film is shown in Table 1.

[Example 7 (comparison)]
BOPP film was obtained from polypropylene using a Ziegler-Natta catalyst containing a multi-component internal electron donor such as (9,9-bis-methoxymethyl-fluorene and diethyl 2,3-diisopropylsuccinate) (US patent). 8003559) was used, and the polypropylene was prepared in the same manner as in Example 1 except that it had the properties shown in Table 1. The process speed of the film is shown in Table 1.

From the table, it can be seen that the process rate of polypropylene depends on its overall structural properties. The amount of xylene-soluble polypropylene fraction and heptane-soluble polypropylene fraction containing a large amount of polymer having a high molecular weight (50,000 g / mol or more for XCS, 400,000 to 3,000,000 g / mol for HS) is (this). When increased (compared to polypropylene according to the invention), the process speed cannot be increased to 450 m / min (as in Comparative Examples 4, 6 and 7). When polypropylene having the same XCS fraction as the polypropylene of the present invention, but the amount of the heptane-soluble fraction does not fall within the range disclosed in the present invention is used (Example 5), the heptane-soluble fraction is used. Due to the excess high molecular weight component, a process rate of 450 m / min is not achieved. Considering the results obtained in Examples 1, 2 and 3 where the values of the heptane and xylene soluble fractions having the specified molecular weight are within the range disclosed in the present invention, it is necessary to achieve high speed in the processing process. It can be said that this is the result of conforming to the above-mentioned characteristics as a whole.

Therefore, in order to achieve a process speed of 450 m / min or more, the following characteristics:
-The amount of cold xylene soluble fraction (XCS) in the polymer is in the range of 2.5 to 4.0% by mass, where the molecular weight of the polymer is mainly 1,500 to 50,000 g / g. The proportion of components within the molar range and having a molecular weight above 50,000 g / mol should not exceed 30% by weight; and-the amount of heptane-soluble fraction (HS) in the polymer is 2.5. It is in the range of ~ 3.5% by mass, and here, the proportion of the polymer having a molecular weight of 400,000 to 3,000,000 g / mol is 10% by mass or less, and 1,500 to 50. It should be observed as a whole that the proportion of components with a molecular weight of 000 g / mol is at least 60% by weight.

Claims (28)

Polypropylene for producing biaxially stretched film,
The polypropylene has the following characteristics:
-The amount of the cold xylene-soluble fraction (XCS) in the polymer is in the range of 2.5 to 4.0% by mass, where the molecular weight of the polymer (macromolecules) of the cold xylene-soluble fraction is. While predominantly in the range of 1,500 to 50,000 g / mol, the proportion of components with a molecular weight above 50,000 g / mol should not exceed 30% by weight; and-the heptane-soluble fraction in the polymer. The amount of (HS) is in the range of 2.5 to 3.5% by mass, and the proportion of the polymer having a molecular weight of 400,000 to 3,000,000 g / mol is 10% by mass or less. Polypropylene, wherein the proportion of the component having a molecular weight of 1,500 to 50,000 g / mol is at least 60% by mass. The polypropylene according to claim 1, which has a molecular weight distribution of 5 to 7. The polypropylene according to claim 2, which has a molecular weight distribution of 6 to 7. The polypropylene according to claim 1, wherein the polypropylene has an isotactic pentad [mm mm] fraction of 87-89%. The polypropylene according to claim 1, wherein the polypropylene contains a stabilizer containing at least one antioxidant and at least one acid absorber, wherein the acid absorber does not belong to the class of metal stearate. .. The polypropylene according to claim 5, wherein the polypropylene contains at least one phenolic antioxidant and at least one phosphite ester antioxidant as stabilizers. The polypropylene according to claim 5 or 6, wherein the polypropylene contains hydrotalcite as an acid absorber. The polypropylene contains 1 to 3 kg of stabilizer per ton of polypropylene, preferably 1.2 to 2.5 kg of stabilizer per ton of polypropylene, and more preferably 1.2 to 1.5 kg of stabilizer per ton of polypropylene. The polypropylene according to claim 5, which is contained. The polypropylene according to claim 1, wherein the polypropylene is substantially free of calcium stearate. The polypropylene according to claim 1, wherein the amount of the cold xylene soluble fraction (XCS) is in the range of 3.0 to 3.8% by mass. The polypropylene according to claim 1, wherein the proportion of the cold xylene-soluble fraction (XCS) having a molecular weight of more than 50,000 g / mol does not exceed 15% by mass, more preferably 5% by mass. The polypropylene according to claim 1, wherein the proportion of the heptane-soluble fraction (HS) having a molecular weight of 1,500 to 50,000 g / mol is at least 70% by mass, preferably at least 75% by mass. A film containing at least one layer containing polypropylene.
The polypropylene has the following characteristics:
-The amount of the cold xylene-soluble fraction (XCS) in the polymer is in the range of 2.5 to 4.0% by mass, and here, the molecular weight of the polymer of the cold xylene-soluble fraction is mainly 1,. The proportion of components having a molecular weight greater than 50,000 g / mol, while in the range of 500-50,000 g / mol, shall not exceed 30% by weight;
-The amount of heptane-soluble fraction (HS) in the polymer is in the range of 2.5-3.5% by weight, where it has a high molecular weight of 400,000-3,000,000 g / mol. A film, wherein the proportion of molecules is 10 mass or less, and the proportion of components having a molecular weight of 1,500 to 50,000 g / mol is at least 60 mass. 13. The film of claim 13, wherein the polypropylene has a molecular weight distribution of 5-7. The film of claim 14, wherein the polypropylene has a molecular weight distribution of 6-7. 13. The film of claim 13, wherein the polypropylene has an isotactic pentad [mm mm] fraction of 87-89%. 13. The film of claim 13, wherein the polypropylene contains a stabilizer comprising at least one antioxidant and at least one acid absorber, wherein the acid absorber does not belong to the class of metal stearate. .. The film according to claim 17, wherein the polypropylene contains at least one phenolic antioxidant and at least one phosphite ester antioxidant as the stabilizer. 17. The film of claim 17, wherein the polypropylene contains hydrotalcite as an acid absorber. 17. The polypropylene contains 1 to 3 kg of a stabilizer per ton of polypropylene, preferably 1.2 to 2.5 kg per ton of polypropylene, more preferably 1.2 to 1.5 kg per ton of polypropylene. The film described in. 13. The film of claim 13, wherein the polypropylene is substantially free of calcium stearate. The film according to claim 13, wherein the amount of the cold xylene-soluble fraction (XCS) in the polypropylene is in the range of 3.0 to 3.8% by mass. 13. the film. 13. The film of claim 13, wherein the proportion of the heptane-soluble fraction (HS) having a molecular weight of 1,500 to 50,000 g / mol in the polypropylene is at least 70% by mass, preferably at least 75% by mass. .. 13. The film of claim 13, wherein the film is produced by coextrusion. The film according to claim 13, wherein the film is a biaxially stretched film. Use of the film according to any one of claims 13 to 26 for manufacturing an article. An article comprising the film according to any one of claims 13 to 26.