ES2267066T3 - TRANSPARENT CONTAINERS OF POLYPROPYLENE TO PACK SHOES. - Google Patents

Abstract

The use of containers that include transparent polypropylenes for packing or storing items related to clothing, sporting goods, toys or articles for the home worker, the container having wall thicknesses of at least 0.8 mm, where the transparent polypropylene is a homopolymer of propylene or a propylene copolymer, which has a darkening value of <_ 40% based on a 1 mm polypropylene thickness, and measured on injection molded test specimens and has a tensile modulus of> _ 700 MPa and a a

Description

Transparent polypropylene containers for pack shoes

The present invention relates to the use of containers made of transparent polypropylene for packing or store items related to clothing, sporting goods, toys or items for the home worker and in particular shoes, specifically transparent polypropylene containers suitable for packing shoes and also systems that include containers made of a transparent polymer that is suitable to pack or store items in the clothing area, items Sports or toys.

To pack items from the clothing area, sporting goods and toys and in particular for packing shoes, two-part cardboard boxes are often used which consist of a box and a lid. A disadvantage of this kind packing is its often unsatisfactory mechanical stability particularly when they crumble one over other such boxes, such as It gets used in many shoe stores. In addition, it is not unusual the packaging and especially the lid deteriorate when the boxes Bottoms are taken out of the carton cracking since Frequently the lid is grabbed to pull the box.

An additional disadvantage of boxed packaging cardboard is that the contents of it cannot be seen. This means that it is necessary either to take the goods out of the box cardboard to facilitate that they are shown in the store, or that the Customers and sales staff can only get information about the content by registering in the outside of the cardboard box. This is also disadvantageous in places where shoes should be regularly taken out of the box and then placed back in it, since it is not easy find shoes placed incorrectly and once they have errors detected, the restore procedure is complicated The original order.

Another additional disadvantage of such a cardboard box It is its low reuse value. Thus, such packaging is essentially disposable which makes it have to be arranged by the buyer or by the seller of the items, and this has associated considerable costs.

The reusable packaging made of plastic, especially for shoes, for example the patent EP-A 659 649. The packages disclosed therein have a folding structure and side sections made of a material flexible that can be folded together.

WO 86/07576 describes shoe boxes of a transparent or translucent plastic. However, I don't know disclose the plastic materials with which they can be produced shoe boxes are particularly advantageous.

Polypropylenes constitute a class of plastics that is often suitable for applications of packaging These generally have advantageous mechanical properties. such as hardness, stiffness and dimensional stability satisfactory They are also economically advantageous.

However, tenacity, particularly at low temperatures, the behavior before whitening by tension, distortion and particularly transparency They often leave something to be desired. An object of the present invention is to overcome the above-mentioned disadvantages of known systems and find containers that are suitable for pack items from the area of clothing, sporting goods and toys and have good mechanical properties, facilitate the packaging manipulation and can be produced economically and with low distortion.

We have found that this goal is achieved by using containers that include polypropylenes transparent to pack or store items related to clothing, sporting goods, toys or articles for the worker homemade, where the containers have wall thicknesses of so minus 0.8 mm, where transparent polypropylene is a propylene homopolymer or propylene copolymer having a dimming value ≤ 40%, based on a thickness of 1 mm polypropylene and measured on molded test specimens  by injection, and having a tensile module? 700 MPa and a Charpy shear impact force ≥ 3 kJ / m2 at 0 ° C.

In addition, we have found containers that include transparent polypropylene that are suitable for purposes of packaging and also systems that include containers that includes a transparent polymer that are suitable for packing or storing articles related to clothing, sporting goods, toys or Items for the home worker.

In accordance with the present invention, it is used a transparent polypropylene to produce the containers. For the present purposes, the term polypropylene refers to a polymer produced from monomers that include at least 50% by weight of propylene. In particular, comonomers are possible α-olefins, that is hydrocarbons that They have double terminal links. The Preferred α-olefins are 1-C 2 -C 20 alkenes linear or branched different from propylene, in particular 1-linear alkenes C_ {2} -C_ {10}  or 1-branched alkenes C 2 -C 10 such as 4-methyl-1-pentene, conjugated and unconjugated dienes such as 1,3-butadiene, 1,4-hexadiene or 1,7-octadiene or vinyl aromatic compounds such as styrene or substituted styrene. The most suitable olefins are those in which the double bond is part of a structure cyclic that may include one or more annular systems. Examples are cyclopentene, norbornene, tetracyclododecene and methylnorbornene and dienes such as 5-ethylidene-2-norbornene, norbornadieno or ethylnorbornadieno. It is also possible Copolymerize mixtures of two or more olefins with propylene. The Particularly preferred olefins are ethylene and linear alkenes. C 4 -C 10 such as 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene and in particular ethylene and / or 1-butene.

The transparent polypropylene used according with the present invention used to produce the containers It has a darkening value, based on a thickness of 1 mm polypropylene and measured on test specimens injection molded in accordance with ASTM D 1003, ≤ 40%, preferably ≤ 25%, in particular preferably ≤ 15%, and very particularly preferably ≤ 12%. The value  dimming is a measure of the opacity of the material and so It is a parameter that characterizes the transparency of the material. The lower the darkening value, the greater the transparency.

The transparent polypropylene also has a advantageous combination of stiffness and toughness. The tensile module of transparent polypropylene is ≥ 700 MPa and preferably ≥ 800 MPa measured in accordance with ISO 527-2: 1993. To determine the tensile modulus, it is given preference to injection molding of a test specimen of type 1 that has a total length of 150 mm and a parallel section 80 mm at a melting temperature of 250 ° C and a temperature of 30 ° C on the surface of the tool. To allow it to happen further crystallization, the test specimens are then stored for 7 days under standard conditions of 23ºC / 50% of atmospheric humidity In determining the module, the speed of The rope should be 1 mm / min. The toughness of polypropylene transparent, determined as the impact force of Charpy cut at 0 ° C, is ≥ 3 kJ / m2, preferably ≥ 4 kJ / m2, and particularly preferably ≥ 6 kJ / m2. The force Charpy cutting impact is measured according to the ISO standard 179-2 / 1eU.

The transparent polypropylene also shows Good behavior to tension bleaching. For the purposes present, stress whitening is the occurrence of a whitish coloration in the region under tension, when the polymer is subjected to mechanical stress. It is generally believed that the Whitening is caused by small voids that form in the polymer under mechanical stress. A good behavior against stress whitening means that under mechanical stress no whitish coloring zones occur, or only zones appear very small.

A method to quantify behavior by stress whitening is to submit definite specimens of test at a defined impact stress, and then measure the size of the resulting white areas. Accordingly, the method of dome excavator involves allowing a dart to fall on the test specimen, using a device of descending darts of according to DIN 53443 part 1. Here a dart was used falling with a mass of 250 g and an impact head diameter of 5 mm The dome has a radius of 25 mm and the height from which it Release the dart is 50 cm. As test specimens discs are used  round injection molded with a diameter of 60 mm and a thickness of 2 mm, and each test specimen is subjected to a single impact test Stress bleaching is reported in mm as the visible diameter of the stress whitening mark, and the reported value is the average of 5 test specimens in each case, the individual values being determined on the side of the round disk opposite the side where the impact occurs, as a average of the two values in the flow direction on the mold of injection and perpendicular to it.

Transparent polypropylene does not show tension whitening at 23 ° C, or if it shows it is very Small, determined by the dome excavator method. If of preferred transparent polypropylenes, using the method of dome excavator was determined at 23 ° C a value of 0 to 8 mm, preferably from 0 to 5 mm, and in particular from 0 to 2.5 mm.

Suitable transparent polypropylenes are propylene homopolymers or preferably copolymers of propylene obtained using catalyst systems based on metallocene compounds.

Suitable transparent polypropylenes they can also be heterophase propylene copolymers, also known as multiphase propylene copolymers or as propylene block copolymers. Such mixtures usually have mixed phases, usually with a polyolefin that has a relatively low stiffness that is dispersed in the matrix of a Propylene polymer that has high rigidity.

Suitable heterophase propylene copolymers as transparent polypropylenes are for example ones that include as a soft phase an ethylene copolymer and 1-butene.

Heterophase propylene copolymers Particularly useful are copolymers that include a polymer A of  propylene forming the matrix and a copolymer B of propylene dispersed within it, where the propylene copolymers of Heterophase have been prepared using catalyst systems based on metallocene compounds.

The propylene polymer A can be a propylene homopolymer or a propylene copolymer with up to a 15% by weight and preferably up to 10% by weight olefins different from propylene, where the preferred copolymers of Propylene contain 1.5 to 7% by weight, in particular 2.5 to 5% by weight, from olefins other than propylene. As a comonomer it is given preference for the use of ethylene or 1-alkenes C4 {C} {C10} linear or mixtures thereof, in particular ethylene and / or 1-butene.

Propylene B copolymers contain usually 5 to 40% by weight of olefins other than propylene. It is also possible that they are used as component B, two or more copolymers other than propylene, which may differ from both the monomer content and the type (s) of olefin (s) other than propylene to be used. As preferred comonomers we have ethylene or 1-linear C_ {4} -C_ {10} alkenes or mixtures thereof, in particular ethylene and / or 1-butene. In an additional preferred embodiment, additionally employ monomers containing at least two double bonds, for example 1,7-octadiene or 1, 9-decadiene. The content of different olefins of propylene in propylene copolymers is generally between 7 and 25% by weight, preferably 10 to 20% by weight, so particularly preferably from 12 to 18% by weight and in particular of 14 to 17% by weight, based on propylene copolymer B.

The weight ratio of propylene polymer A The propylene copolymer B may vary. It is preferably from 90:10 to 60:40, particularly preferably from 80:20 to 60:40 and very particularly preferably from 70:30 to 60:40 where Propylene B copolymers are all propylene copolymers that form with component B.

Preferably such transparent polypropylene preferred has a narrow molar mass distribution M_ {w} / M_ {n}. For the purposes of the invention, the molar mass distribution M_ {w} / M_ {n} is the weight ratio of the average molar mass M_ {w} and the number of average molar mass M_ {n}. The molar mass distribution M_ {w} / M_ {n} is preferably in the range of 1.5 to 3.5, particularly preferably from 1.8 to 2.5 and in particular in the range of 2 to 2.3.

The average molar mass M_ {n} of such preferred transparent polypropylene is preferably in the range of 20,000 g / mol to 500,000 g / mol, in particular preferably from 50,000 g / mol to 200,000 g / mol, and so very particularly preferably from 80,000 g / mol to 150,000 g / mol.

To prepare such transparent polypropylenes preferred, preference is given to the use of a system of catalyst based on metallocene compounds of metals from transition of groups 3, 4, 5 or 6 of the Periodic Table of Elements.

Particular preference is given to systems of catalyst based on metallocene compounds that have the formula (I)

one

Where

M

it is zirconium, hafnium or titanium, preferably zirconium

X are identical or different and are each, independently of each other, hydrogen or halogen or a group -R, -OR, -OSO2CF3, -OCOR, -SR, -NR2 or -PR2, where R is alkyl C 1 -C 20 linear or branched, cycloalkyl C_ {3} -C_ {20} that can support one or more radicals as alkyl substituents C_ {1} -C_ {{10}}, aril C_ {6} -C_ {20}, rented C 7 -C 20 or arylalkyl C 7 -C 20 and may contain one or more hetero atoms of groups 13-17 of the Periodic Table of the Elements or one or more unsaturated bonds and is preferably C 1 -C 10 alkyl such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentile, n-hexyl, n-heptyl or n-octyl or cycloalkyl C 3 -C 20 - such as cyclopentyl or cyclohexyl, where the radicals X can also be attached to each other other and preferably form a dienyl ligand C 4 -C 40, in particular a ligand 1,3-dienyl, or a -OR'O-, group in which the R 'substituent is a divalent group selected from the group that consists of C 1 -C 40 alkylidene, arylidene C_ {6} -C_ {40}, alkylarylidene C 7 -C 40 and arylalkylidene C 7 -C 40, where X is preferably a halogen atom or a group -R or -OR or the two X radicals form a group -OR'O- and X is in particular preferably chlorine or methyl.

L It is a divalent group that bridges, selected from the group consisting of radicals C 1 -C 20 alkylidene, cycloalkylidene C 3 -C 20, arylidene C_ {6} -C_ {20}, alkylarylidene C 7 -C 20 and arylalkylidene C 7 -C 20 which may contain hetero atoms of groups 13-17 of the Periodic Table of the Elements, or is a silylidene group that has up to 5 atoms of silicon, for example -SiMe_ {2} - or -SiPh_ {2} -, where L is preferably a radical selected from the groups consisting in -SiMe_ {2} -, -SiPh_ {2} -, -SiPhMe-, -SiMe (SiMe_ {3}) -, -CH 2 -, - (CH 2) 2 -, - (CH 2) 3 - and -C (CH 3) 2

R1 is alkyl C 1 -C 20 linear or branched, cycloalkyl C_ {3} -C_ {20} which can support as substituents one or more alkyl radicals C_ {1} -C_ {{10}}, aril C_ {8} -C_ {20}, rented C 7 -C 20, or arylalkyl C 7 -C 20 and may contain one or more hetero atoms of groups 13-17 of the Periodic Table of the Elements or one or more unsaturated bonds, where R1 is preferably not branched in position a and is preferably a linear C 1 -C 10 alkyl group or branched, which is unbranched in the α position, in particular a linear C 1 -C 4 alkyl group, such as methyl, ethyl, n-propyl or n-butyl

R2 is a group of the formula -C (R 3) 2 R 4 where

R3 are identical or different and are each one, independently of each other, rents C_ {1} -C_ {linear or branched 20, C 3 -C 20 cycloalkyls that can withstand as one or more radical substituents C 1 -C 10 alkyl, aryls C_ {6} -C_ {20}, rented C 7 -C 20, or arylalkyl C 7 -C 20 and may contain one or more hetero atoms of groups 13-17 of the Periodic Table of the Elements or one or more unsaturated bonds, or two radicals R 3 may be attached to form a ring C 3 -C 20 saturated or unsaturated

Where R 3 is preferably a group C 1 -C 10 linear or branched alkyl, and

R 4 is hydrogen or alkyls C_ {1} -C_ {linear or branched 20, C 3 -C 20 cycloalkyls that can withstand as one or more radical substituents C 1 -C 10 alkyl, aryls C_ {6} -C_ {20}, rented C 7 -C 20, or arylalkyl C 7 -C 20 and may contain one or more hetero atoms of groups 13-17 of the Periodic Table of the Elements or one or more unsaturated bonds, where R 4 is preferably a hydrogen.

T and T 'are divalent groups of the formulas (II), (III), (IV), (V) or (VI)

2

Where the atoms denoted by the symbols * and ** are linked in each case to the atoms of the compounds of the formula (I), which are denoted by the same symbol, and

R 5 are identical or different and are each one, independently of each other, hydrogen or halogen or linear or branched C 1 -C 20 alkyls, C 3 -C 20 cycloalkyls that can withstand as one or more radical substituents C 1 -C 10 alkyl, aryls C_ {6} -C_ {20}, rented C 7 -C 20, or arylalkyl C 7 -C 20 and may contain one or more hetero atoms of groups 13-17 of the Periodic Table of the Elements or one or more unsaturated bonds, where R 5 is preferably hydrogen or alkyl groups C_ {1} -C_ {10} linear or branched, in particular a linear C 1 -C 4 alkyl group, such as methyl, ethyl, n-propyl or n-butyl, and

R 6 are identical or different and are each one, independently of each other, halogen or alkyls C_ {1} -C_ {linear or branched 20, C 3 -C 20 cycloalkyls that can withstand as one or more radical substituents C 1 -C 10 alkyl, aryls C_ {6} -C_ {20}, rented C 7 -C 20, or arylalkyl C 7 -C 20 and may contain one or more hetero atoms of groups 13-17 of the Periodic Table of the Elements or one or more unsaturated bonds, where R 6 is preferably an aryl group of the formula (VII)

3

Where

R 7 are identical or different and are each one, independently of each other, hydrogen or halogen or linear or branched C 1 -C 20 alkyls, C 3 -C 20 cycloalkyls that can withstand as one or more radical substituents C 1 -C 10 alkyl, aryls C_ {6} -C_ {20}, rented C 7 -C 20, or arylalkyl C 7 -C 20 and may contain one or more hetero atoms of groups 13-17 of the Periodic Table of the Elements or one or more unsaturated bonds, or two radicals R 7 may be attached to form a ring C_ {3} -C_ {saturated or unsaturated, where R 7 is preferably a hydrogen atom and

R 8 is hydrogen or halogen or alkyls C_ {1} -C_ {linear or branched 20, C 3 -C 20 cycloalkyls that can withstand as one or more radical substituents C 1 -C 10 alkyl, aryls C_ {6} -C_ {20}, rented C 7 -C 20, or arylalkyl C 7 -C 20 and may contain one or more hetero atoms of groups 13-17 of the Periodic Table of the Elements or one or more unsaturated bonds, where R 8 is preferably a branched alkyl group of the formula -C (R 9) 3 where

R 9 are identical or different and are each one, independently of each other, rent groups C_ {1} -C_ {6} linear or branched or two or three R 9 radicals are joined to form one or more systems annular

It is preferred that at least one of the groups T and T is substituted by a radical R 6 of the formula (VII) and is given particular preference that both groups be replaced by such radical. Very particular preference is given to at least one of the groups T and T is a group of the formula (IV) which is substituted by a radical R 6 of the formula (VII) and the other has either formula (II) or formula (IV) and similarly substituted by a radical R 6 of the formula (VII).

A very particular preference is given to systems of catalyst based on metallocene compounds of the formula (VIII).

4

In WO 01/48034 and in the patent application International No. PCT / EP 02/13552, for example, are described particularly useful metallocene compounds as well as their preparation processes

It is also possible to use mixtures of several metallocene compounds or mixtures of various catalyst systems. However, preference is given to the use of a single system of catalyst that includes a metallocene compound, this being used for the polymerization of propylene polymer A and the propylene copolymer B.

Examples of metallocene compounds are

dichloride dimethylsilanodiyl- (2-ethyl-4- (4'-tert-butylphenyl) indenyl) - (2-isopropyl-4- (4'-tert-butylphenyl) -indenyl) zirconium,

bichloride dimethylsilanodiyl- (2-methyl-4- (4'-tert-butylphenyl) indenyl) -2-isopropyl-4- (1-naphthyl) indenyl) zirconium,

dichloride dimethylsilanodiyl- (2-methyl-4-phenyl) -1-indenyl) - (2-isopropyl-4- (4'-tert-butylphenyl) - 1-indenyl) zirconium,

dichloride dimethysilanodiyl- (2-methylthiapentenyl) - (2-isopropyl-4- (4'-tert-butylphenyl) indenyl) zirconium,

dichloride dimethylsilanodiyl- (2-isopropyl-4- (4'-tert-butylphenyl) indenyl) - (2-methyl-4,5-bencindenyl) zirconium,

dichloride dimethylsilanoiyl- (2-methyl-4- (4'-tert-butylphenyl) indenyl) - (2-isopropyl-4- (4'-tert-butylphenyl) indenyl) zirconium,

dichloride dimethylsilanodiyl- (2-methyl-4- (4'-tert-butylphenyl) indenyl) - (2-isopropyl-4-phenylindenyl) zirconium,

dichloride dimethylsilanodiyl- (2-ethyl-4- (4'-tert-butylphenyl) indenyl) - (2-isopropyl-4-phenyl) indenyl) zirconium or dichloride of dimethylsilanodiyl- (2-isopropyl-4- (4'-tert-butylphenyl) indenyl) - (2-methyl-4- (1-naphthyl) indenyl) -circonium or mixtures thereof.

Additionally, the preferred systems of catalyst based on metallocene compound generally in addition include compounds capable of forming metallocene ions as Cocatalysts Suitable cocatalysts include acids Strong and uncharged Lewis, ionic compounds that have cations Lewis-acid and ionic compounds containing Brönsted acids as cation. Examples are tris (pentafluorophenyl) borane, tetrakis (pentafluorophenyl) borate and salts of N, N-dimethylanilinium. Additional compounds that are suitable as compounds capable of forming metallocene ions and so as cocatalysts are open chain compounds or compounds aluminoxane cyclic. These are usually prepared by reaction between trialkylaluminum and water and are present generally as mixtures of both linear chain molecules and cyclic of different lengths or cage molecules of various sizes. Usually preferred catalyst based systems in metallocene compounds they are used in the supported form. Suitable supports are, for example, porous inert solids. organic or inorganic, such as finely polymerized powders divided or inorganic oxides, for example silica gel. The metallocene catalyst systems may also include organometallic compounds of metals of groups 1, 2 and 13 of the Periodic Table, for example alkyls of n-butyllithium or aluminum.

In the preparation of heterophase mixtures particularly preferred, it is preferred to initially polymerize the propylene polymer A in a first stage by polymerization, from 90% by weight to 100% by weight of propylene, with based on the total weight of the mixture, if desired in the presence of other olefins, usually at 40ºC-120ºC and pressures in the range of 0.5 bar to 200 bar. In a second stage, it subsequently polymerizes a mixture of 2% to 95% by weight of propylene and 5 to 98% by weight of additional olefins up to polymer obtainable by means of the reaction in the first stage, usually at 40-120 ° C and pressures in the range of 0.5 bar to 200 bar. Preferably the polymerization is carried out. of propylene polymer A at 60 ° C - 80 ° C, in particular preferably at 65 ° C - 75 ° C and a pressure of 5 to 100 bar, so particularly preferably from 10 to 50 bar. Preferably it takes the polymerization of the propylene copolymer B at 60 ° C - 80 ° C, particularly preferably at 65 ° C - 75 ° C and a pressure 5 to 100 bar, particularly preferably 10 to 50 Pub.

They can also be used in polymerization. traditional additives, such as molar mass regulators such as hydrogen or inert gases such as nitrogen or argon.

Preferably, the mixture of propylene copolymers B of such preferred transparent polypropylenes, prepared using catalyst systems based on metallocene compound, is uniform. They include small comonomers incorporated in blocks. The term "block incorporated" is used to mean that two or more comonomer units follow one another directly. In preferred polypropylene copolymers B obtained from propylene and ethylene, the structure can be determined by 13 C-NMR spectroscopy. Spectrum evaluation is a known technique and can be carried out by a trained person using for example the HN Cheng method, Macromolecules 17 (1984), pp. 1950-1955, or L. Abis et al ., Makromol. Chemie 187 (1986), pp. 1877-1886. The structure can then be described by the proportions of "PE_ {x}" and "PEP" where PE_ {x} refers to the propylene-ethylene units having two or more successive units of ethylene and PEP refers to units of propylene-ethylene having an isolated unit of ethylene between two propylene units, Preferred mixtures of propylene copolymers obtained from propylene and ethylene have a PEP / PE x ratio in the range of 0.75 to ≥ 1, 00, preferably in the range of 0.85 and ≥ 1.4 and particularly preferably in the range of 0.85 to 1.2 and in particular in the range of 0.9 to 1.1.

In the case of the preferred use of ethylene as comonomer, particular preference is given to an ethylene content in propylene copolymers B from 10% to 20% by weight, in in particular from 12 to 18% by weight and particularly preferably approximately 16% by weight. The transparency of mixtures of propylene copolymers used in accordance with the present invention, is virtually independent of the proportion of propylene copolymer B present.

They are also propylene copolymers of particularly useful heterophase, suitable as polypropylenes transparent, which include

TO)

of 50 to 98, preferably 60 to 95% by weight of a homopolymer propylene crystalline, or a random crystalline copolymer of propylene with ethylene and / or 1-alkenes C 4 -C 10, containing 0.5 to 15% in weight of ethylene and / or 1-alkenes C_ {4} -C_ {{}}, and

B)

of 2 to 50, preferably 5 to 40% by weight of (i) a copolymer Elastomeric ethylene with one or more 1-alkenes C 4 -C 10 (copolymer (a)), which contains 60 to 85% by weight of ethylene or (ii) a mixture of the copolymer (a) with a propylene copolymer with more than 15 and up to 40% ethylene copolymer (b), where the weight ratio (a) / (b) is preferably 1/4 to 4/1.

Examples of 1-alkenes C_ {4} -C_ {10} that can be used as comonomer in Fractions A and b are 1-butene, 1-pentene, 1-hexene and 4-methyl-1-pentene. Particularly preferred is 1-butene.

The MFR (230ºC / 2.16 kg) determined according to ISO 1133 of such heterophase propylene copolymers is preferably 0.1 to 100 g / 10 min.

Such useful copolymers of heterophase of propylene, are typically prepared by copolymerization sequential monomers in the presence of catalysts stereospecific Ziegler Natta supported on dihalides of magnesium. The polymerization is carried out in at least two stages: in the first stage the synthesis of the polymer of Fraction A; in the second, the polymer synthesis of the Fraction B. The synthesis of the latter occurs in the presence of the polymer obtained and the catalyst used in the preceding step. The reaction times and the relative temperatures of the two stages are not critical and are advantageously in the range of 0.5 to 5 hours and from 50 ° C to 90 ° C, respectively. The regulation of the molecular weight using molecular weight regulators commonly used as hydrogen or Zn Et2.

Suitable stereospecific catalysts include the product of the reaction between:

(i)

A solid component, which contains a titanium compound, and a electron donor compound (internal electron donor) supported on magnesium chloride

(ii)

A alkyl aluminum compound (cocatalyst), and optionally

(iii)

A electron donor compound (external electron donor)

Such catalysts are preferably capable. of producing polypropylene homo polymer having an index isotactic greater than 90%.

The catalysts that have the characteristics Above mentioned are well known in the literature of patents; The catalysts described are particularly advantageous. in US-A 4,399,054 and EP-A 45977.

The component (i) of the solid catalyst contains, as an electron donor, a selected compound generally among ethers, ketones, lactones, compounds that they contain atoms of N, P and / or S, and esters of mono and dicarboxylic.

The esters of the phthalic and succinic acids. Other electron donors Particularly suitable are 1.3 diesters, as illustrated in published European patent applications EP-A 361 493 and EP-A 728 769.

As cocatalysts (ii) are used preferably trialkylaluminum compounds, such as triethyl-Al, triisobutyl-Al and tri-n-butyl-Al.

The electron donor compounds (iii) that can be used as external electron donors (added to the Alkyl-Al compound) include esters of aromatic acids (such as alkyl benzoates), compound heterocyclic (such as 2,2,6,6-tetramethylpiperidine and the 2,6-diiso propylpiperidine) and in particular a silicon compounds containing at least one bond Si-OR (where R is a hydrocarbon radical). The 1, 3 previously mentioned diesters are also suitable for use as external donors. In the event that the internal donor is one of said 1, 3 diesters, the external donor can be omitted.

The preparation of polypropylenes Transparent particularly useful, obtained by using of catalyst systems based on metallocene compounds or using Ziegler Natta stereospecific catalysts supported on magnesium dihalides, it is preferably performed in a multistage polymerization process that has at least two polymerization stages connected in series, generally in the form of a cascade reactor. It is possible to use the reactors used to be used for the polymerization of propylene. Polymerization can be carried out in the known manner to bulk, in suspension, in the gas phase or in a medium supercritical. It can be run in batches or preferably in form keep going. Possible processes are the processes in solution, suspension, agitation in gas phase or gas phase in bed fluidized It is possible to use as a solvent or suspension medium, inert hydrocarbons, for example isobutane, or the monomers in themselves. It is also possible to run in two or more reactors, one or more stages of the process used in accordance with this invention.

The size of the reactors is not important Critical to the processes used in accordance with this invention. It depends on the amount of output that must be obtained in the reaction zone or in individual reaction zones.

Preference is given to processes in which the second polymerization stage, in which the propylene copolymers B or fraction B, takes place in the phase soda. Prior polymerization of polymers A of propylene or fraction A can be carried out either in bulk, that is in liquid propylene as a suspension medium, or similarly from the gas phase If all polymerizations take place from the gas phase, preferably the process is executed in a reactor cascade or in gas phase reactors with stirring, which they are connected in series and in which the powdery reaction bed, by means of a vertical stirrer. Generally, the reaction bed includes the polymer that is polymerized in the respective reactor. If carried out in bulk the initial polymerization of propylene polymers A, preferably the process is done in a cascade reactor that includes one or more return reactors and in one or more reactors of gas phase with fluidized bed. It can also be done Preparation in a multizone reactor.

The amount of monomers added in individual stages and process conditions such as pressure, temperature, or the addition of molar mass regulators such as hydrogen, so that the polymers formed have the desired properties

They can also be used in polymerization customary additives, for example molar mass regulators such as hydrogen or inert gases such as nitrogen or argon.

Additionally transparent polypropylenes include additives known to people versed in the subject, as stabilizers, lubricants and mold release agents, fillers, nucleating agents, antistatic agents, plasticizers, dyes, pigments, flame retardants, in quantities accustomed They are usually incorporated during the granulation of the pulverulent product obtained in the polymerization.

Antioxidants are used as stabilizers such as sterically hindered phenols, stabilizers of process such as phosphites or phosphonites, acid consumers as calcium stearate or zinc stearate or dihydrotalcite, sterically hindered amines or UV stabilizers. In general, the mixtures of propylene copolymer used in accordance with the present invention contain one or more stabilizers in amounts up to 2% by weight.

Suitable lubricants and agents are mold release, for example, fatty acids, zinc salts or calcium fatty acids, fatty acid amides, or waxes low molecular weight polyolefins, which are used generally in concentrations of up to 2% by weight.

Possible fillings are, for example, talc, chalk or glass fibers, which can usually be used in amounts up to 50% by weight.

They are suitable nucleating agents, for for example, inorganic additives such as talc, silica or kaolin, salts of monocarboxylic or polycarboxylic acids, ie benzoate sodium or aluminum tert-butylbenzoate, dibenzylidensorbitol or its substituted alkyl derivatives C 1 -C 8 such as metildi benzylidensorbitol, ethyldibenzylidensorbitol dimethyldibenzylidensorbitol or salts of acid diesters phosphoric, such as 2,2'-methylenebis phosphate (4,6-di-tert-butylphenyl) sodium. The content of nucleating agents in mixtures of Propylene polymer is generally up to 5%.

Generally such additives are available commercially and are described, for example, in Gächter / Müller, Plastics Additives Handbook, 4th Edition, Hansa Publishers, Munich, 1993

In a preferred embodiment, polypropylenes transparent contain 0.1 to 1% by weight, preferably of 0.15 to 0.25% by weight of a nucleating agent, in particular dibenzylidensorbitol or a derivative of dibenzylidensorbitol, in Particularly preferably dimethyldibenzylidensorbitol.

The containers are used to pack or store items related to clothing, sporting goods, toys or items for the home worker. For example they They are suitable for storing or storing shoes of all types, sandals, boots, sports shoes, boots for skiing or skating online, laundry, tennis items, toys such as carts or building blocks, or articles for the worker Homemade tools, screws, nails. In particular, the Containers are used to store or store shoes.

The containers have wall thicknesses of at least 0.8 mm and preferably at least 1.0 mm. He container wall thickness is generally approximately The same in all regions of the container. However, also they can have reinforced regions or frames. Generally the containers have dimensions that allow you to easily pack the items, especially shoes.

Preferred containers are made of two parts and consist of a box-shaped receptacle and a lid. The receptacle and the lid can be attached to each other, in particular by means of a film hinge. The receptacle in the form of box and lid are preferably configured so that in the closed state of the containers, the receptacle and the lid, adjust.

In addition, the receptacles are preferably configured in such a way that, in an empty state, they can be ruin one inside the other. Usually this is achieved by giving the receptacles a conical shape. Preference is also given to reinforcement of the upper edge around the outside of the receptacles, to provide rigidity. Also, this does more simple to achieve the fit between the receptacle and the lid, in the state Closed containers.

A possible design is shown in the attached figure of a preferred container made of a box-shaped receptacle and a lid

The covers are preferably designed with short side parts which usually have between 10 and 20 mm height It is also preferred that the bottom edge of the lid is reinforced around its inner part to provide rigidity. Additionally, this makes it easier to achieve the adjustment of the receptacle and lid when containers are in condition closed.

Preferably, the containers are produced by injection molding. However, containers can also obtained by forming, for example, folding, of sheets extruded and in particular extruded corrugated sheets.

Additionally, the present invention provides containers that include transparent polypropylene, having the wall thickness containers of at least 0.8 mm, where the Transparent polypropylene is a homopolymer of propylene or a propylene copolymer having a darkening value of ≤ 40% based on a polypropylene thickness of 1 mm and measured on injection molded test specimens, and has a tensile module of ≥ 700 MPa and a cutting impact force Charpy at 0 ° C of ≥ 3 kJ / m2, and the containers have in the bottom a material with a sliding friction coefficient which is larger than that of transparent polypropylene. This material prevents, or at least reduces, slipping items packed or stored, such as shoes. Are examples of suitable materials that have a coefficient of friction of slip that is higher than that of transparent polypropylene, thermoplastic elastomers or elastomers such as thermoplastic polyolefins or oligoblock copolymers of styrene Suitable thermoplastic polyolefins are marketed, for example, by Bassel under the name of Adflex. In general, the containers have, only in some regions of the bottom, a material with a sliding friction coefficient. These regions can be, for example, oval, in the form of strips rectangular, or with the shape of the foot. Production can be carried out, for example, by injection molding of two components However, it is also possible to manufacture separately the containers and the moldings with the material with a sliding friction coefficient, and then fix the moldings to the container by for example an adhesive of link.

Claims (8)

1. The use of containers that include transparent polypropylenes for packing or storing items related to clothing, sporting goods, toys or items for the home worker, having the container thicknesses of wall of at least 0.8 mm, where the transparent polypropylene is a propylene homopolymer or a propylene copolymer, which has a darkening value of ≤ 40% based on a thickness 1 mm polypropylene, and measured on test specimens injection molded and has a tensile module of ≥ 700 MPa and a Charpy cutting impact force at 0 ° C of ≥ 3 kJ / m2. 2. The use of containers as claimed in Claim 1, wherein the containers are used for Pack or store shoes. 3. The use of containers as claimed in claims 1 or 2, wherein the containers have two parts and consist of a box-shaped receptacle and a lid, where the receptacle and the lid can be attached to each other 4. The use of containers as claimed in any one of Claims 1 to 3, wherein the box-shaped receptacle and lid so that when containers are in a closed state, the lid and the container adjust. 5. The use of containers as claimed in any one of Claims 1 to 4, wherein they are configured the receptacles so that when they are empty they can be stacked inside each other. 6. The use of containers as claimed in any one of Claims 1 to 5, wherein the containers They are produced by injection molding. 7. A container that includes polypropylene transparent having the container wall thicknesses of so minus 0.8 mm, where transparent polypropylene is a homopolymer of propylene or a copolymer of propylene, which has a value of blackout of ≤ 40% based on a polypropylene thickness 1 mm, and measured on test specimens molded by injection, which has a tensile module of ≥ 700 MPa and one Charpy cutting impact force at 0 ° C of ≥ 3 kJ / m2 and the containers have a material with a coefficient of sliding friction that is greater than polypropylene transparent. 8. The use of containers as claimed in any one of Claims 1 to 6, wherein the containers they are containers as claimed in Claim 7.