KR20060009296A - Transparent polypropylene containers for packaging shoes - Google Patents

Abstract

The present invention relates to the use of containers comprising transparent polypropylene for packaging or storing articles from the area of clothing, sports articles, toys or home worker articles, with the containers having wall thicknesses of at least 0.8 mm, and the transparent polypropylene is a propylene homopolymer or propylene copolymer which has a haze value of <_ 40%, based on a thickness of polypropylene of 1 mm and measured on injection-molded test specimens, and has a tensile modulus of >_ 700 MPa and a Charpy notched impact strength at 0°C of >_ 3 kJ/m2. In addition, the invention relates to containers comprising transparent polypropylene which are suitable for packaging purposes and also systems comprising containers made of a transparent polymer which are suitable for packaging or storing articles from the area of clothing, sports articles, toys or home worker articles.

Description

Transparent Polypropylene Containers for Packaging Shoes}

The present invention relates to the use of transparent polypropylene containers for packaging or storing articles in the field of clothing, sporting goods, toys or domestic worker articles, in particular shoes, in particular transparent polypropylene containers suitable for shoe packaging, and clothing, A system comprising a transparent polymer container suitable for packaging or storing articles in the field of sports articles or toys.

Two-part cardboard boxes consisting of boxes and lids are frequently used for packing articles in the field of clothing, sporting goods or toys, in particular for packing shoes. One drawback of this type of packaging is that its mechanical stability is often unsatisfactory, especially when many shoe boxes are stacked on top of each other, as is common in many shoe stores. In addition, since the lid is frequently pulled to pull the box, it is common for the packaging, especially the lid, to be damaged when pulling the box below among the loaded cardboard boxes.

Another drawback of cardboard packaging is the inability to see the contents of the box. This means that it is necessary to take the goods out of the cardboard box so that they can be displayed in the store, or that the customer and the salesperson can only get information about the contents by the description on the outside of the cardboard box. This is also disadvantageous in cases where the shoes are ritually taken out of the cardboard box and must be reinserted. This is because it is difficult to find if the shoes are not placed properly, and restoring the original order when a mistake is found is a complicated procedure.

Another drawback of such cardboard packaging is its low reuse value. Accordingly, such packaging is essentially disposable packaging, which must be disposed of by the buyer or seller of the article, which is associated with significant cost.

Reusable packaging of plastics, in particular such packaging for shoes, is known for example from EP-A 659 649. The container disclosed therein has a collapsible frame and side compartments of flexible material that can be folded together.

Shoe boxes made of transparent or translucent plastics are described in WO 86/07576. However, no plastics are disclosed which make it possible to produce shoe boxes in particular advantage.

Polypropylene constitutes a class of plastics that are often well suited for packaging applications. It generally has advantageous mechanical properties such as satisfactory hardness, robustness and dimensional stability. It is also economically advantageous.

However, toughness, particularly low temperature toughness, stress whitening behavior, warpage, and especially transparency often leave room for improvement.

The object of the present invention is to overcome the drawbacks of the prior art and to be suitable for packaging articles in the field of articles apparel, sports articles or toys, having good mechanical properties, making the packaging easier to handle and economically It is also looking for a container that can be manufactured with low distortion.

I am a container containing transparent polypropylene for the purpose of packaging or storing goods in the field of clothing, sporting goods, toys or domestic worker goods, the container having a wall thickness of at least 0.8 mm and the transparent polypropylene of 1 mm. Charpy notches at a tensile modulus of ≥700 MPa and ≥3 kJ / m ² at 0 ° C with a haze value of ≤40% when measured on injection molded specimens based on the thickness of polypropylene It has been found that this is achieved by using a container that is a propylene homopolymer or propylene copolymer with Charpy notched impact strength.

In addition, they seek a system comprising a container comprising a transparent polypropylene suitable for packaging purposes and a container containing a transparent polymer suitable for packaging or storing articles in the field of apparel, sporting goods, toys or household worker goods. Came out.

According to the invention, transparent polypropylene is used to prepare the container. For this purpose, the term polypropylene refers to a polymer made of monomers comprising at least 50% by weight of propylene. Possible comonomers are in particular α-olefins, ie hydrocarbons having terminal double bonds. Preferred α-olefins are linear or branched C ₂ -C ₂₀ -1-alkenes other than propylene, in particular linear C ₂ -C ₁₀ -1-alkenes or branched C ₂ -C ₁₀ -1-alkenes, such as 4-methyl -1-pentene, conjugated and nonconjugated dienes such as 1,3-butadiene, 1,4-hexadiene or 1,7-octadiene or vinylaromatic compounds such as styrene or substituted styrene. Suitable olefins are also olefins in which the double bond is part of a cyclic structure which may comprise one or more ring systems. Examples are cyclopentene, norbornene, tetracyclododecene and methylnorbornene, and dienes such as 5-ethylidene-2-norbornene, norbornadiene or ethylnorbornadiene. It is also possible for a mixture of two or more olefins to copolymerize with propylene. Particularly preferred olefins are ethylene and linear C ₄ -C ₁₀ -1-alkenes such as 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene and especially ethylene and / or 1- Butene.

The transparent polypropylene used according to the invention for the production of a container is, in accordance with standard ASTM D 1003, ≦ 40%, preferably measured on an injection molded specimen based on a thickness of 1 mm polypropylene. It has a haze value of ≦ 25%, particularly preferably ≦ 15% and very particularly preferably ≦ 12%. The haze value is a measure of the opacity of a material and is therefore a parameter characterizing the transparency of the material. The smaller the haze value, the greater the transparency.

Transparent polypropylene also has an advantageous combination of robustness and toughness. The tensile modulus of the transparent polypropylene is ≧ 700 MPa, preferably ≧ 800 MPa when measured according to ISO 527-2: 1993. To determine the tensile modulus of elasticity, it is desirable to injection mold type 1 specimens having a total length of 150 mm and a parallel section of 80 mm at a melting temperature of 250 ° C., and a tool surface temperature of 30 ° C. To further crystallize, the specimens are then stored for 7 days under standard conditions at 23 ° C./50% atmospheric humidity. In determining the modulus of elasticity, the strain should be 1 mm / min. The toughness of the transparent polypropylene is ≧ 3 kJ / m ² , preferably ≧ 4 kJ / m ² , particularly preferably ≧ 6 kJ / m ² , as determined by Charpy notch impact strength at 0 ° C. Charpy notch impact strength is measured according to standard ISO 179-2 / 1 eU.

Transparent polypropylene also exhibits good stress whitening behavior. For this purpose, stress whitening is where whitening of the stressed areas occurs when mechanical stress is applied to the polymer. Whitening is generally believed to be caused by small pores formed in the polymer under mechanical stress. Good stress whitening behavior means that there are no or only very small areas where whitening discoloration occurs under mechanical stress.

One quantification method of stress whitening behavior is to apply a defined impact stress to a defined specimen and then measure the size of the white spot obtained. Thus, the dome indenter method involves dropping a dart onto a specimen using a drop dart device in accordance with DIN 53443 Part 1. Dropping darts with a mass of 250 g and an impact head diameter of 5 mm are used here. The dome radius is 25 mm and the height the dart drops is 50 cm. An injection molded circular disk having a diameter of 60 mm and a thickness of 2 mm is used as the specimen, and only one impact test is performed on each specimen. The stress whitening is expressed as the diameter of the visible stress whitening mark in mm, the value indicated is the average of five specimens in each case, and the individual value is the flow direction during injection molding, with respect to the face of the circular disk opposite to the face on which the impact occurs. And an average of two values in the direction perpendicular thereto.

Clear polypropylene shows no or only very little stress whitening at 23 ° C., as determined by the dome indenter method. In the case of preferred transparent polypropylenes, values of 0 to 8 mm, preferably 0 to 5 mm, in particular 0 to 2.5 mm, are determined at 23 ° C. using the dome indenter method.

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

Suitable transparent polypropylenes can also be heterophasic propylene copolymers, also known as multiphase propylene copolymers or propylene block copolymers. Such compositions have predominantly demixed phases and generally polyolefins having relatively low firmness are dispersed in a matrix of propylene polymer having higher firmness.

Heterophasic propylene copolymers suitable as transparent polypropylenes are, for example, those comprising a copolymer of ethylene and 1-butene as the flexible phase.

Particularly useful heterophasic propylene copolymers are copolymers comprising propylene polymer A forming a matrix, and propylene copolymer B dispersed therein, wherein the heterophasic propylene copolymer is prepared using a catalyst system based on metallocene compounds. Copolymer.

The propylene polymer A can be a propylene homopolymer or a copolymer of propylene with olefins other than propylene at most 15% by weight, preferably at most 10% by weight, with the preferred propylene copolymer being 1.5 to 7% by weight, in particular 2.5 to 5 Olefins other than propylene by weight. As comonomer, preference is given to using ethylene or linear C ₄ -C ₁₀ -1-alkenes or mixtures thereof, in particular ethylene and / or 1-butene.

Propylene copolymer B mainly contains 5 to 40% by weight of olefins other than propylene. Also possible are two or more different propylene copolymers which may differ both in terms of comonomer content and in terms of the type of olefin (s) other than propylene used as component B. Preferred comonomers are ethylene and linear C ₄ -C ₁₀ -1-alkenes or mixtures thereof, in particular ethylene and / or 1-butene. In another preferred embodiment, monomers containing two or more double bonds, such as 1,7-octadiene or 1,9-decadiene, are additionally used. The content of olefins other than propylene in the propylene copolymer is generally from 7 to 25% by weight, preferably from 10 to 20% by weight, particularly preferably from 12 to 18% by weight, in particular from 14 to 17% by weight relative to propylene copolymer B. %to be.

The weight ratio of propylene polymer A to propylene copolymer B may vary. It is preferably 90:10 to 60:40, particularly preferably 80:20 to 60:40, very particularly preferably 70:30 to 60:40, and the propylene copolymer B comprises all the propylene air that forms component B May be coalescing.

Such preferred transparent polypropylenes preferably have a narrow molar mass distribution M _w / M _n . For the purposes of the present invention, the molar mass distribution M _w / M _n is the ratio of the weight average molar mass M _w and the number 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 in the range of 1.8 to 2.5, in particular in the range of 2 to 2.3.

The average molar mass M _n of such preferred transparent polypropylenes is preferably in the range of 20000 g / mol to 500000 g / mol, particularly preferably in the range of 50000 g / mol to 200000 g / mol, very particularly preferably 80000 g / it is in the range of mol to 150000 g / mol.

In order to produce such a preferred transparent polypropylene, preference is given to using catalyst systems based on metallocene compounds of transition metals of Groups 3, 4, 5 or 6 of the Periodic Table of the Elements.

Especially preferred are catalyst systems based on metallocene compounds of formula (I):

[Wherein M is zirconium, hafnium or titanium, preferably zirconium,

X is the same or different and each independently of the other hydrogen or halogen or -R, -OR, -OSO ₂ CF ₃ , -OCOR, -SR, -NR ₂ or -PR ₂ groups, wherein R is linear or minute Terrain C ₁ -C ₂₀ -alkyl, C ₃ -C ₂₀ -cycloalkyl, C ₆ -C ₂₀ -aryl, C ₇ -C ₂₀ -alkylaryl, which may have one or more C ₁ -C ₁₀ -alkyl radicals as substituents Or C ₇ -C ₂₀ -arylalkyl, which may contain a hetero atom or at least one unsaturated bond of group 13-17 of the Periodic Table of the Elements, preferably C ₁ -C ₁₀ -alkyl, such as methyl, ethyl, n -Propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl or n-octyl, or C ₃ -C ₂₀ -cycloalkyl, such as cyclopentyl Or cyclohexyl); The radicals X can also be interconnected, preferably C ₄ -C ₄₀ -dienyl ligands, in particular 1,3-dienyl ligands, or —OR′O—groups where the substituents R ′ are C ₁ -C ₄₀ -Alkylidene, C ₆ -C ₄₀ -arylidene, C ₇ -C ₄₀ -alkylarylidene and C ₇ -C ₄₀ -arylalkylidene); X is preferably a halogen atom or an -R or -OR group, or two radicals X form an -OR'O- group, X is particularly preferably chlorine or methyl,

L is capable of containing a heteroatom of group 13-17 of the periodic table of elements, C ₁ -C ₂₀ - alkylidene, C ₃ -C ₂₀ - cycloalkylidene, C ₆ -C ₂₀ - O-ylidene, C ₇ - C ₂₀ - alkyl, O-ylidene, and C ₇ -C ₂₀ - aryl or a divalent linking group selected from the group consisting of an alkylidene radical, a chamber release dengi having silicon atoms of 5 or less, for example, -SiMe ₂ - or -SiPh ₂ -; L is preferably -SiMe _2- , -SiPh _2- , -SiPhMe-, -SiMe (SiMe ₃ )-, -CH ₂ -,-(CH ₂ ) ₂ -,-(CH ₂ ) ₃ -and -C ( CH ₃ ) ₂ is a radical selected from the group consisting of

R ¹ is linear or branched C ₁ -C ₂₀ -alkyl, C ₃ -C ₂₀ -cycloalkyl, C ₆ -C ₂₀ -aryl, C ₇ which may have one or more C ₁ -C ₁₀ -alkyl radicals as substituents -C ₂₀ -alkylaryl or C ₇ -C ₂₀ -arylalkyl, which may contain one or more heteroatoms or one or more unsaturated bonds of group 13-17 of the Periodic Table of the Elements; R ¹ is preferably unbranched at the α position, preferably a linear or branched C ₁ -C ₁₀ -alkyl group, in particular a linear C ₁ -C ₄ -alkyl group, such as methyl, ethyl, n-propyl Or n-butyl,

R ² is a group of the formula —C (R ³ ) ₂ R ⁴ , wherein

R ³ is the same or different and each independently of each other a linear or branched C ₁ -C ₂₀ -alkyl, C ₃ -C ₂₀ -cycloalkyl, which may have one or more C ₁ -C ₁₀ -alkyl radicals as substituents, C _6- C ₂₀ -aryl, C ₇ -C ₂₀ -alkylaryl or C ₇ -C ₂₀ -arylalkyl, which may contain one or more heteroatoms or one or more unsaturated bonds of group 13-17 of the Periodic Table of the Elements, or Radicals R ³ may join together to form a saturated or unsaturated C ₃ -C ₂₀ ring; R ³ is preferably a linear or branched C ₁ -C ₁₀ -alkyl group,

R ⁴ is hydrogen or linear or branched C ₁ -C ₂₀ -alkyl, C ₃ -C ₂₀ -cycloalkyl, C ₆ -C ₂₀ -aryl, which may have one or more C ₁ -C ₁₀ -alkyl radicals as substituents, C ₇ -C ₂₀ -alkylaryl or C ₇ -C ₂₀ -arylalkyl, which may contain one or more heteroatoms or one or more unsaturated bonds of groups 13-17 of the Periodic Table of the Elements; Preferably hydrogen,

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

(Wherein the atoms denoted by the symbols * and ** are bonded to the atoms of the compound of formula (I) denoted by the same symbol in each case),

C ₃ -C _20, which may have an alkyl radical - R ⁵ are the same or different, each independently represent hydrogen or halogen or linear or branched C ₁ -C ₂₀ - alkyl, one or more C ₁ -C ₁₀ group as a substituent - Cycloalkyl, C ₆ -C ₂₀ -aryl, C ₇ -C ₂₀ -alkylaryl or C ₇ -C ₂₀ -arylalkyl, which may contain one or more heteroatoms or one or more unsaturated bonds of groups 13-17 of the Periodic Table of the Elements Can; R ⁵ is preferably hydrogen or a linear or branched C ₁ -C ₁₀ -alkyl group, in particular a linear C ₁ -C ₄ -alkyl group, such as methyl, ethyl, n-propyl or n-butyl,

R ⁶ are the same or different and are each independently of the other halogen or linear or branched C ₁ -C ₂₀ -alkyl, C ₃ -C ₂₀ -cycloalkyl which may have one or more C ₁ -C ₁₀ -alkyl radicals as substituents , C ₆ -C ₂₀ -aryl, C ₇ -C ₂₀ -alkylaryl or C ₇ -C ₂₀ -arylalkyl, and may contain one or more heteroatoms or one or more unsaturated bonds of groups 13-17 of the Periodic Table of the Elements ; R ⁶ is preferably an aryl group of formula (VII):

From here,

One or more C ₁ -C ₁₀ an alkyl, an optionally substituted - - R ⁷ are the same or different and each mutually independently represent hydrogen or halogen or linear or branched C ₁ -C ₂₀ alkyl radical which may have a C ₃ -C ₂₀ - Cycloalkyl, C ₆ -C ₂₀ -aryl, C ₇ -C ₂₀ -alkylaryl or C ₇ -C ₂₀ -arylalkyl, which may contain one or more heteroatoms or one or more unsaturated bonds of groups 13-17 of the Periodic Table of the Elements Or two radicals R ⁷ may join together to form a saturated or unsaturated C ₃ -C ₂₀ ring; R ⁷ is preferably a hydrogen atom,

R ⁸ is hydrogen or halogen or linear or branched C ₁ -C ₂₀ -alkyl, C ₃ -C ₂₀ -cycloalkyl which may have one or more C ₁ -C ₁₀ -alkyl radicals as substituents, C ₆ -C _20- Aryl, C ₇ -C ₂₀ -alkylaryl or C ₇ -C ₂₀ -arylalkyl, which may contain one or more heteroatoms or one or more unsaturated bonds of groups 13-17 of the Periodic Table of the Elements; R ⁸ is preferably a branched alkyl group of the formula -C (R ⁹ ) ₃ , wherein

R ⁹ is the same or different and each independently of each other is a linear or branched C ₁ -C ₆ -alkyl group, or two or three radicals R ⁹ combine to form one or more ring systems.

It is preferred that at least one of the T and T 'groups be substituted by the radical R ⁶ of formula (VII), with particular preference being given to both groups being substituted by such radicals. At least one of the T and T 'groups is a group of formula (IV) substituted with a radical R ⁶ of formula (VII), the other having the formula (II) or (IV) and likewise a radical R of formula (VII) Very particular preference is given to substitution by ⁶ .

Very particular preference is given to catalyst systems based on metallocene compounds of formula (VIII):

Particularly useful metallocene compounds and methods for their preparation are described, for example, in WO 01/48034 and International Patent Application No. PCT / EP02 / 13552.

It is also possible to use mixtures of various metallocene compounds, or mixtures of various catalyst systems. However, preference is given to using only one catalyst system comprising one metallocene compound, which is used for the polymerization of propylene polymer A and propylene copolymer B.

Examples of suitable metallocene compounds are dimethylsilanediyl- (2-ethyl-4- (4'-tert-butylphenyl) indenyl)-(2-isopropyl-4- (4'-tert-butylphenyl) Indenyl) zirconium dichloride, dimethylsilandiyl- (2-methyl-4- (4'-tert-butylphenyl) indenyl) -2-isopropyl 4- (1-naphthyl) indenyl) zirconium dichloride , Dimethyldimethyldiyl- (2-methyl-4-phenyl) -1-indenyl)-(2-isopropyl-4- (4'-tert-butylphenyl) -1-indenyl) zirconium dichloride, dimethyl Silanediyl- (2-methylthiapentenyl)-(2-isopropyl-4- (4'-tert-butylphenyl) indenyl) zirconium dichloride, dimethylsilandiyl- (2-isopropyl- 4- (4'-tert-butylphenyl) indenyl)-(2-methyl-4,5-benzinyl) zirconium dichloride, dimethylsilandiyl- (2-methyl-4- (4'-tert- Butylphenyl) indenyl)-(2-isopropyl-4- (4'-tert-butylphenyl) indenyl) zirconium dichloride, dimethylsilandiyl- (2-isopropyl-4- (4'-tert- Butylphenyl) indenyl)-(2-methyl-4- (1 -Naphthyl) indenyl) zirconium dichloride or mixtures thereof.

In addition, preferred catalyst systems based on metallocene compounds generally further comprise compounds capable of forming metallocene ions as cocatalysts. Suitable promoters include strong uncharged Lewis acids, ionic compounds with Lewis acid cations, and ionic compounds containing Bronsted acid as a cation. Examples are the salts of tris (pentafluorophenyl) borane, tetrakis (pentafluorophenyl) borate and N, N-dimethylanilinium. It is also suitable as a compound capable of forming metallocenium ions, and thus a compound suitable as a promoter is an open chain or cyclic aluminoxane compound. It is mainly prepared by reacting trialkylaluminum with water and is generally present as a mixture of linear and cyclic chain molecules of various lengths or cage molecules of various sizes. Preferred catalyst systems based on metallocene compounds are mainly used in supported form. Suitable supports are, for example, porous organic or inorganic inert solids such as finely divided polymer powder or inorganic oxides such as silica gel. The metallocene catalyst system may further comprise organometallic compounds of Group 1, 2 and 13 metals of the Periodic Table of Elements, such as n-butyllithium or aluminum alkyl.

In the preparation of particularly preferred heterophasic compositions, 90 to 100% by weight of propylene, relative to the total weight of the mixture, is polymerized, if desired, in the presence of further olefins, mainly at pressures ranging from 40 ° C. to 120 ° C. and from 0.5 bar to 200 bar. It is therefore preferred to first polymerize propylene polymer A in the first step. In a second step, a mixture of 2 to 95% by weight of propylene and 5 to 98% by weight of additional olefins is obtained by the reaction of the first step, mainly at pressures in the range 40 ° C. and 120 ° C. and 0.5 bar to 200 bar. Subsequent polymerization may be possible on the polymer. The polymerization of propylene polymer A is preferably carried out at a pressure of 60 to 80 ° C., particularly preferably 65 to 75 ° C., and 5 to 100 bar, particularly preferably 10 to 50 bar. The polymerization of the propylene copolymer B is preferably carried out at a pressure of 60 to 80 ° C., particularly preferably 65 to 75 ° C. and 5 to 100 bar, particularly preferably 10 to 50 bar.

Conventional additives such as molar mass regulators such as hydrogen or inert gases such as nitrogen or argon may also be used for the polymerization.

The composition of the propylene copolymer B of such a preferred transparent polypropylene prepared using a catalyst system based on a metallocene compound is preferably uniform. It contains very few comonomers incorporated into the block. The expression “incorporated into blocks” is used by meaning that two or more comonomer units are directly connected to each other. In a preferred propylene copolymer B obtained from propylene and ethylene, the structure can be determined by ¹³ C-NMR spectroscopy. Evaluation of the spectra is a prior art and is described, for example, in HN Cheng, Macromolecules 17 (1984), pp. 1950-1955 or [L. Abis et al., Makromol. Chemie 187 (1986), pp. 1877-1886], which can be performed by one of ordinary skill in the art. The structure then refers to "PE _x " and "PEP", where PE _x refers to propylene-ethylene units having ≧ 2 consecutive ethylene units, and PEP is propylene- having an ethylene unit isolated between two propylene units. Fraction of ethylene units). Preferred propylene copolymer compositions obtained from propylene and ethylene are PEP / PE _x ratios in the range from 0.75 to ≧ 1, preferably in the range from 0.85 to ≧ 1.4, particularly preferably in the range from 0.85 to 1.2, in particular in the range from 0.9 to 1.1. Has

When ethylene is preferably used as comonomer, it is particularly preferred that the ethylene content of propylene copolymer B is 10 to 20% by weight, in particular 12 to 18% by weight, particularly preferably about 16% by weight. The transparency of the propylene copolymer composition used according to the invention is substantially independent of the fraction of propylene copolymer B present.

Particularly useful heterophasic propylene copolymers suitable as clear polypropylenes are also those comprising:

A) 50 to 98% by weight, preferably 60 to 95% by weight of crystalline propylene homopolymer, or propylene and ethylene containing 0.5 to 15% by weight of ethylene and / or C ₄ -C ₁₀ -1-alkene And / or a crystalline random copolymer of C ₄ -C ₁₀ -1-alkene; And

B) an elastomeric copolymer of ethylene and at least one C ₄ -C ₁₀ -1-alkene containing 2 to 50% by weight, preferably 5 to 40% by weight of (i) 60 to 85% by weight of ethylene ( Copolymer (a)), or (ii) a copolymer of (a) and a copolymer of propylene and greater than 15% to 40% ethylene (copolymer (b)), wherein the weight ratio (a) / (b) is preferably 1/4 to 4/1).

Examples of C ₄ -C ₁₀ -1-alkenes that can be used as comonomers in fractions A and B are 1-butene, 1-pentene, 1-hexene and 4-methyl-1-pentene. Especially preferred is 1-butene.

The MFR (230 ° C./2.16 kg) determined according to ISO 1133 of such heterophasic propylene copolymer is preferably 0.1 to 100 g / 10 min.

Such useful heterophasic propylene copolymers are typically prepared by sequential copolymerization of monomers in the presence of a stereospecific Ziegler-Natta catalyst supported on magnesium dihalide. The polymerization is carried out in two or more stages. That is, in the first step, the synthesis of the polymer of fraction A is carried out, and in the second step the synthesis of the polymer of fraction B is carried out. The latter synthesis takes place in the presence of the polymer obtained and the catalyst used in the previous step. The reaction time and temperature for the two steps are not critical, but are advantageously in the range of 0.5 to 5 hours, and 50 ° C. to 90 ° C., respectively. Control of the molecular weight is carried out by the use of commonly used molecular weight regulators such as hydrogen and ZnEt ₂ .

Suitable stereospecific catalysts include the products of reactions between the following materials:

i) a solid component containing a titanium compound supported on magnesium chloride and an electron donor compound (internal electron donor);

ii) aluminum alkyl compounds (promoters); And optionally

iii) electron donor compound (external electron donor).

The catalyst can preferably produce homopolymer polypropylenes having an isotropic index greater than 90%.

Catalysts having this property are known from the patent literature; Particularly advantageous are the catalysts described in US Pat. No. 4,399,054 and EP-A 45977.

Solid catalyst component (i) is an electron donor and generally contains a compound containing ether, ketone, lactone, N, P and / or S atoms, and a compound selected from mono and dicarboxylic acid esters.

Especially suitable are phthalic acid ester and succinic acid ester. Another particularly suitable electron donor is the 1,3-diethers exemplified in published European patent applications EP-A 361 493 and EP-A 728 769.

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

Electron donor compounds (iii) which can be used as external electron donors (in addition to Al-alkyl compounds) include aromatic acid esters (eg alkyl benzoates), heterocyclic compounds (eg 2,2,6,6-tetra Methylpiperidine and 2,6-diisopropylpiperidine), in particular silicon compounds containing at least one Si-OR bond, wherein R is a hydrocarbon radical. The 1,3-diethers described above are also suitable for use as external donors. If the internal donor is one of the 1,3-diethers, the external donor can be omitted.

Particularly useful transparent polypropylenes obtained by using catalyst systems based on metallocene compounds or using stereospecific Ziegler-Natta catalysts supported on magnesium dihalide are preferably two or more polymerisations, usually in the form of a reactor cascade. The steps are produced in a multistage polymerization process connected in series. It is possible to use conventional reactors used for the polymerization of propylene. The polymerization can be carried out in a known manner in bulk, suspension, gas phase or supercritical media. It may be carried out batchwise or preferably continuously. Solution processes, suspension processes, stirred gas phase processes or gas phase fluidized bed processes are all possible. As a solution or suspending medium, it is possible to use inert hydrocarbons such as isobutane or the other monomers themselves. It is also possible for one or more steps of the method used according to the invention to be used in two or more reactors. The size of the reactor is not critically important for the method used according to the invention. It depends on the output to be achieved in the reaction zone, or in the individual reaction zone.

Preference is given to the process in which the polymerization takes place from the gas phase in the second stage in which the propylene copolymer (s) B or fraction B is formed. The previous polymerization of propylene polymer A or fraction A can be carried out in bulk, ie in liquid propylene as suspending medium, or likewise from the gas phase. If all the polymerizations take place from the gas phase, the process is preferably carried out in a cascade of stirred gas phase reactors in which the powder reaction bed is kept in motion by a vertical stirrer. The reaction layer generally comprises a polymer polymerized in each reactor. If the initial polymerization of propylene polymer A is carried out in bulk, the process preferably consists of a cascade comprising at least one loop reactor or at least one gas phase fluidized bed reactor. The preparation can also be carried out in a multi-zone reactor.

The amount of monomer added to the individual steps, and process conditions such as the addition of pressure, temperature or molar mass regulators such as hydrogen, are selected such that the polymer formed has the desired properties.

Conventional additives such as molar mass regulators such as hydrogen or inert gases such as nitrogen or argon may also be used in the polymerization.

Clear polypropylene generally further comprises conventional amounts of additives known to those skilled in the art, such as stabilizers, lubricants and release agents, fillers, nucleating agents, antistatic agents, plasticizers, dyes, pigments or flame retardants. It is generally incorporated during the granulation of the powder product obtained in the polymerization.

Common stabilizers are antioxidants, hindered phenols, process stabilizers such as phosphites or phosphonites, acid scavengers such as calcium stearate or zinc stearate or dehydrotalcite, hindered amines or UV stabilizers . Generally, the propylene copolymer composition used according to the present invention contains at least one stabilizer in an amount of up to 2% by weight.

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

Possible fillers are, for example, talc, chalk or fiberglass which can be used predominantly in amounts of up to 50% by weight.

Suitable nucleating agents are, for example, inorganic additives such as talc, silica or kaolin, salts of monocarboxylic or polycarboxylic acids such as sodium benzoate or aluminum tert-butylbenzoate, dibenzylidenesorbitol Or its C ₁ -C ₈ -alkyl-substituted derivatives such as methyldibenzylidenesorbitol, ethyldibenzylidenesorbitol or dimethyldibenzylidenesorbitol or salts of diesters of phosphoric acid, such as sodium 2,2'-methylenebis ( 4,6-di-tert-butylphenyl) phosphate. The content of nucleating agent in the propylene polymer composition is generally 5% by weight or less.

Such additives are generally commercially available and are described, for example, in Gachter / Muller, Plastics Additives Handbook, 4th edition, Hansa Publishers, Munich, 1993.

In one preferred embodiment, the transparent polypropylene contains 0.1 to 1% by weight, preferably 0.15 to 0.25% by weight of nucleating agents, in particular dibenzylidenesorbitol or dibenzylidenesorbitol derivatives, particularly preferably dimethyldibenzylidenesorbitol do.

Containers are used to package or store articles in the field of apparel, sporting goods, toys or home worker articles. For example, it may be used for all types of footwear articles, such as shoes, sandals, boots, sports shoes, roller blades or ski boots, laundry, tennis articles, toys, such as toy cars or building blocks or household worker articles such as tools, screws Or suitable for packing or storing nails. In particular, containers are used to package or store shoes.

The container has a wall thickness of at least 0.8 mm, preferably at least 1.0 mm. The wall thickness of the vessels is generally about the same in all areas of the vessels. However, it may have reinforcement regions or ribs. Containers generally have dimensions to facilitate packaging of articles, in particular shoes.

The preferred container has two parts and consists of a box-shaped container and a lid. The container and the lid can be joined together, in particular via a film hinge. The box-shaped container and the lid are preferably arranged so that the container and the lid fit together with the container closed.

The container is also preferably configured such that it can be loaded into each other in an empty state. This is mainly achieved by providing the container with a cone. It is also desirable for the upper rim of the inner container to be reinforced near the outside to be firm. It also makes it simpler to allow the container and lid to fit together with the container closed.

One possible design of a preferred container consisting of a boxed container and a lid is shown in the accompanying drawings.

The lid is preferably designed as a short side part which is mainly 10 to 20 mm high. It is also desirable for the bottom edge of the lid to be reinforced near its interior to be firm. It also makes it simpler to allow the container and lid to fit together with the container closed.

The container is preferably produced by injection molding. However, the container can also be obtained by molding, for example folding, an extruded sheet, in particular an extruded corrugated sheet.

The invention also relates to a container comprising transparent polypropylene, wherein the container has a wall thickness of at least 0.8 mm and the transparent polypropylene has a ≧ 40% when measured on specimens that have been injection molded based on the thickness of the polypropylene of 1 mm. The sliding friction coefficient of the transparent polypropylene at the bottom of the container is a propylene homopolymer or propylene copolymer having a haze value of ≥ 700 MPa and a Charpynotch impact strength at 0 ° C. of ≥ 3 MPJ / m ² . Provided is a container provided with a material having a greater sliding coefficient of friction. This material prevents or at least reduces slipping of the packaged or stored articles, such as shoes. Examples of suitable materials having a sliding friction coefficient greater than the sliding friction coefficient of the transparent polypropylene are elastomers or thermoplastic elastomers such as thermoplastic polyolefin or styrene oligoblock copolymers. Suitable thermoplastic polyolefins are commercially available, for example under the trade name Adflex by Basell. In general, the bottom of the container is provided with a material having an increased sliding friction coefficient in only a few areas. This area can be oval, for example, or in the form of a rectangular strip or foot shape. The preparation can be carried out, for example, by two-component injection molding. However, it is also possible to fix the molding to the container, for example by adhesive bonding, after separately preparing the container and the material having an increased sliding friction coefficient.

The invention is also a system for packaging or storing articles in the field of apparel, sporting goods, toys or home worker articles, wherein at least two objects are present in the package, wherein the objects have a wall thickness of at least 0.8 mm. Provided is a system surrounded by a container comprising a polymer, wherein two or more objects are separated from each other by a transparent flexible film. Such a system consists of two or more objects and facilitates viewing of the packaged article in a form such that the objects are reliably protected from impact with the wall or with each other during transportation of the packaging system.

Examples of suitable transparent polymers that can be used to make containers of the system are polystyrene, polycarbonates, styrene-butadiene block copolymers and polypropylenes, which are particularly useful.

Preferred transparent films are flexible and have low firmness. In addition, preferred transparent films are made from materials having a coefficient of sliding friction greater than that of the transparent polymer. Suitable transparent films can be made, for example, from thermoplastic polyolefins, such as thermoplastic polyolefins sold under the trade name aflex by Basel.

The present invention relates to a reusable packaging system for packaging apparel, sporting goods, toys or home worker articles, in particular shoes, wherein a container comprising a transparent polymer and having a wall thickness of at least 0.8 mm is a garment, sporting article, toy or home worker article. Additional systems provide a system wherein smaller containers, which are used to package the product and which can fit or fit into the container, can be reused. This insert is preferably of the same transparent polymer used to make the container. The insert may also consist of a sorting vessel having a plurality of compartments, for example 2-10, preferably 4-8 compartments.

Suitable inserts may be sold empty as a supplement for further use of the container that originally served as the packaging material. However, the insert may be sold already filled, ie as a reusable package for another item. Suitable articles that can be packaged and sold in such inserts are, for example, shoe care products such as glossy tubes, cleaning equipment or cleaning cloths or sewing necessities such as needles, threads or buttons.

Suitable transparent polymers that can be used to prepare the containers of the system are, for example, styrene-butadiene block copolymers of polystyrene, polycarbonate, polypropylene, wherein such transparent polypropylenes are particularly useful.

Claims (10)

As a use of a container comprising transparent polypropylene, The container has a wall thickness of at least 0.8 mm, The transparent polypropylene had a haze value of ≤40% when measured on an injection molded specimen based on a thickness of 1 mm polypropylene, a tensile modulus of ≥ 700 MPa and 0 ° C. of ≥ 3 kJ / m ² . Propylene homopolymer or propylene copolymer having Charpy notched impact strength in Use of a container comprising transparent polypropylene for packaging or storing articles in the field of apparel, sporting goods, toys or home worker articles. The use of a container according to claim 1, wherein the container is used for packaging or storing shoes. The use of a container according to claim 1 or 2, wherein the container is in two parts, consisting of a box-shaped inner container and a lid, and wherein the inner container and the lid can be joined together. The use of a container according to any one of claims 1 to 3, wherein the box-shaped inner container and the lid are formed such that the inner container and the lid are fitted together with the container closed. 5. Use of a container according to any one of claims 1 to 4, wherein the container is formed so that it can be loaded inside each other in an empty state. 6. Use of a container according to any one of claims 1 to 5, wherein the container is produced by injection molding. A container comprising a transparent polypropylene, wherein the container has a wall thickness of at least 0.8 mm, the transparent polypropylene having a haze of ≤ 40% when measured on an injection molded specimen based on a thickness of 1 mm polypropylene. Propylene homopolymer or propylene copolymer having a tensile modulus of ≥ 700 MPa and a Charpy notch impact strength at 0 ° C. of ≥ 3 MPJ / m ² , the vessel being less than the sliding friction coefficient of Wherein the material is provided having a greater sliding coefficient of friction. Use of a container according to any one of claims 1 to 6, wherein the container is a container according to claim 7. A system for packaging or storing articles in the field of apparel, sporting goods, toys, or home worker articles, wherein at least two objects are present in the package, the objects having a wall thickness of at least 0.8 mm and comprising a transparent polymer. Surrounded by two or more objects separated from each other by a transparent flexible film. A reusable packaging system for packaging apparel, sporting goods, toys or home worker articles, wherein a container comprising a transparent polymer and having a wall thickness of 0.8 mm or more is used for packing apparel, sporting goods, toys or home worker articles A system in which a smaller container that can exactly fit into or fit into the container is reusable.

Images