CZ20001866A3 - Material containing crystalline copolymer of polypropylene - Google Patents

Abstract

A material comprising a crystalline polypropylene copolymer contains (A) 20 to 80 wt. at least one copolymer propylene, e.g., propylene / ethylene copolymer, copolymer propylene with at least one 4 to 8 alpha-olefin % of carbon, and (B) 20 to 80 wt. at least one copolymer propylene with another comonomer or other comonomer than in (A). Single-layer or multi-layer film or sheet it comprises at least one crystalline-containing layer of a propylene copolymer of the above composition.

Description

Technical field

The present invention relates to a material comprising a crystalline 5 propylene copolymer useful for the production of heat-sealable films, flat materials and films made therefrom, and a process for the manufacture of such materials.

BACKGROUND OF THE INVENTION Crystalline copolymers of propylene with other olefins (especially ethylene, 1-butene, or both), or mixtures of these copolymers with other olefin polymers are known in the art as heat sealable materials.

Crystalline copolymers are obtained by polymerizing propylene with minor amounts of other olefin monomers in the presence of coordination catalysts.

The polymerized comonomer units are statistically distributed in the resulting copolymer, and the melting point of said copolymers is thus lower than the melting point of crystalline propylene homopolymers.

Also, the welding initiation temperature (hereinafter to be defined in detail) of said copolymers is consequently acceptably low.

However, the introduction of comonomer units adversely affects the crystal structure of the polymer, resulting in relatively large amounts of polymer fraction soluble in organic solvents, so that copolymers with a particularly low welding initiation temperature cannot be used in the food packaging area.

· 04 4440 ·· 44 • 40 0 4 0 040 · 4 000 004 · · · · · 00 00 ·

440 0 · 4 ···· · · 044 44 4 ·· ··

A large number of technical solutions have been described in the prior art in order to find a good balance between heat weldability (shown at low welding initiation temperatures) and solubility.

In particular, European Patent Application 483523 discloses materials made directly during polymerization having a low welding initiation temperature and a low fraction soluble in xylene at room temperature or in n-hexane at 50 ° C. These materials include:

up to 60% by weight of a copolymer of propylene and a C4-C8 alpha-olefin containing from 80 to 98% by weight of propylene;

up to 70% by weight of a copolymer of propylene with ethylene and optionally 1 to 10% by weight of a C4-C8 alpha-olefin, wherein the ethylene content is 5 to 10% by weight if C4-C8 alpha-olefin is not present, or 0.5 to 5% by weight if a C ₄ -C 8 alpha olefin is present.

Published European Patent Application 674991 discloses other materials made directly in the polymerization process which, in addition to the low welding initiation temperature and the low content of polymeric fraction soluble in organic solvents, have good ink adhesion.

These materials include:

up to 60% by weight of a copolymer of propylene with ethylene containing 1 to 5% by weight of ethylene;

to 80% by weight of a copolymer of propylene with ethylene and C4-C8 alpha-olefin wherein the ethylene content is up to 5% by weight and the content of _C4-C8 alpha-olefin content being 6-15% by weight;

wherein the total ethylene content of the materials is 1 to 5% by weight and the total C ₄ -C 8 alpha-olefin content in the materials is 2.4 to 12% by weight.

• 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9

9 9 9 · 9 9999 * ········

Other heat-sealable materials comprising two different types of copolymers of propylene with higher alpha-olefins are described in published European patent application 560326.

On the other hand, it is known that generally the Melt Flow 5 Rate (MFR) of an olefin polymer can be modified by degradation, particularly by elevated temperatures in the presence of a free radical initiator (a process known as "visbreaking").

It is also known in the art of heat-sealable olefin copolymers that this degradation action can improve the heat-obtained weld, optical and solubility properties, as explained in particular in US Patent 5,246,769 and Japanese Published Patent Application Sho 59-117506.

In these two documents, however, the degradation action takes place on individual copolymers of propylene with ethylene and / or higher alpha-olefins, resulting in a still high welding initiation temperature.

One approach to applying a degradation treatment to heat-sealable materials containing two copolymers of propylene with ethylene and / or higher alpha-olefins is the process described in published European patent application 203727. In this case, propylene copolymer with 25-45% by weight 1- butene is then degraded and then mixed with another propylene copolymer with ethylene and / or 1-butene.

However, while satisfactory values for welding initiation temperature and turbidity are obtained, the content of the organic solvent soluble fraction of the resulting product is high (the content of the fraction soluble at 25 ° C in xylene of about 30% by weight is considered satisfactory).

Surprisingly, it has now been found that a particularly valuable balance between the heat-sealing properties, the low content of organic solvent soluble fraction and the optical properties (particularly very low * 9999 9 9 9 9 9

9 9 9 9 9

9 9 99 99 9 9 9

9 · 9 · 9 · ·

(Turbidity) is obtained by subjecting specific materials containing a crystalline polypropylene copolymer to a degradation treatment.

SUMMARY OF THE INVENTION

Accordingly, the present invention provides materials containing a crystalline propylene copolymer having MFR L values from 2 to 15 g / 10 min, preferably from 3 to 15 g / 10 min, more preferably from 4 to 10 g / min, comprising:

A) 20 to 80% by weight, preferably 30 to 50% by weight, of one or more propylene copolymers selected from (A1) propylene / ethylene copolymers containing 1-7% by weight ethylene; (A 2) propylene copolymers with one or more C4-C8 alpha-olefins, containing 2 to 10% by weight of C4-C8 alpha15 olefins; (A 3) copolymers of propylene with ethylene and one or more C4-C8 alpha-olefins, containing from 0.5 to 4.5 wt% of ethylene and 2-6% of C ₄ -CS alpha-olefins, provided that the total ethylene and C ₄ -C 8 alpha-olefins in group (A 3) will be equal to or less than 6.5% by weight;

B) 20 to 80% by weight, preferably 40 to 80% by weight, more preferably 50 to 70% by weight, of one or more propylene copolymers selected from group (B 1) propylene copolymers with one or more

C ₄ -C 8 alpha-olefins, containing from more than 10% by weight to 30% by weight of C ₄ -C ₈ alpha-olefins; (B 2) copolymers of propylene with ethylene and one or more C4-C8 alpha-olefins containing 1 to 7% by weight of ethylene and 6 to 15% by weight of C4-C _with alpha-olefins;

444

- 5 * 4 4

4 4

4 4

4 · 44

4 4 4 4

4 4 4

44 wherein said MFR L values (MFR L (2)) are obtained by exposing a precursor composition containing the same components A) and B) in the above proportions, with MFR L values (MFR L (1)) of 0, 3 to 5 g / 10 min, preferably from 0.5 to 3 g / 10 min, with a degradation action, wherein the ratio of MFR L (2) to MFR L (1) is from 2 to 20, preferably from 3 to 15.

It is clear from the above definitions that the term "copolymer" includes polymers containing more than one kind of comonomers.

As already mentioned, the materials of the present invention also have low welding initiation temperatures (preferably less than 100 ° C), low fractions soluble or extractable in organic solvents (preferably equal to or less than 20% by weight for xylene at 25 ° C) and equal to or less than 5% by weight for nhexane at 50 ° C) and very low haze values (preferably less than

1%, more preferably a haze value equal to or less than 0.5%, the measurement being carried out on the films as described in the Example section).

The melting point of said material is preferably from about 126 to 147 ° C.

In addition, the materials of the present invention can be obtained in an efficient and inexpensive manner that represents another embodiment of the present invention and which comprises the following steps;

1) preparing the above starting material by polymerizing monomers in at least two consecutive steps wherein the components

A) and B) are prepared in separate consecutive steps, each step being carried out in the presence of the polymer formed and the catalyst used in the preceding step, and the molecular weight regulator (preferably hydrogen) is metered in such amounts as to obtain MFR L (1) for starting material from

0.3 to 5 g / 10 min, preferably from 0.5 to 3 g / 10 min;

· «·· v • t »··» • · • · • • ·· • ·· • • · • · • • • »· • • • · • • • • • ♦ r

(2) the starting material obtained in (1) is subjected to a degradation treatment to obtain MFR L (2) values for the final material from 3 to 15 g / 10 min, preferably from 4 to 10 g / 10 min, with a degradation ratio expressed as MFR L (2) / MFR L (1) ratio from 2 to 20, preferably from 3 to 15.

Such a preferred method is extremely advantageous since it avoids separate preparation of the components of the starting material and a separate degradation action.

It should be clear from the foregoing description that in the starting material, the comonomer content and the relative amounts of components A) and B) are the same as in the final material (after degradation). The degradation effect leads to an increase in the MFR L of the material from MFR L (1) to MFR L (2), with the ratio values between the two MFR L, i.e. MFR L (2) / MFR L (1) being between 2 and 20. Values given

MFR L is measured according to ASTM D 1238 L.

The MFR L values of components A) and B) are not particularly critical for either the starting material or the finished material, provided that the MFR L values of the material as a whole fall within these ranges.

Suitably, the starting material has MFR L values of both 20 components A) and B) of from 0.1 to 10 g / 10 min.

Preferred comonomer contents in the materials of the present invention are:

and 4% by weight of ethylene for (A1);

up to 8% by weight of one or more C4-C8 alpha25 olefins for (A 2);

up to 4% by weight of ethylene and 2 to 5% by weight of one or more C4-C8 alpha-olefins with a total ethylene and C4-C8 alpha-olefin content equal to or less than 6% by weight for (A 3);

up to 20% by weight of one or more C4-C8 alphaolefins for (B (1);

up to 4% by weight of ethylene and 7 to 12% by weight of one or more C4-C8 alpha-olefins for (B2).

In addition, if optimum ink adhesion is desired, the materials of the present invention should contain component (A1) and component (B2) in the above relative amounts, while the total ethylene content of the materials should be 1 to 5% by weight, preferably 2% by weight. up to 4% by weight and the total amount of C ₄ 10 C 8 alpha-olefins in the same materials should be 2.4 to 12% by weight, preferably 3.5 to 8.4% by weight.

Examples of C4-C8 alpha-olefins are 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene and 1-octene. 1-Butene is particularly preferred.

As explained above, starting materials can be produced by sequential polymerization. Such polymerization is carried out in the presence of stereospecific Ziegler-Natta catalysts. An essential component of said catalysts is a solid catalyst component comprising a titanium compound containing at least one titanium-halogen bond and an electron donor compound, both of which are in active form on the magnesium halide support. Another necessary component (cocatalyst) is an organoaluminum compound, such as an alkyl aluminum compound.

An external donor is added if necessary.

The catalysts generally used in the process of the invention are capable of providing polypropylene with an isotactic index greater than 90%, preferably greater than 95%. Catalysts having the above properties are well known in the patent literature; particularly preferred are the catalysts disclosed in US Patent 4,399,054 and European Patent 45977.

• »»

- 8 ··· ······················

The solid catalyst components used in said catalysts comprise as electron donors (internal donors) compounds selected from the group of ethers, ketones, lactones, compounds containing N, P and / or S atoms, and mono- and dicarboxylic acid esters.

Particularly suitable electron donor compounds are phthalic acid esters such as diisobutyl, dioctyl, diphenyl and benzylbutyl phthalate.

Other particularly useful electron donors are 1,3-diethers of the formula:

wherein R ¹ and R ¹¹ are identical or different and denote a Cu-Cis alkyl, C315 cycloalkyl cis or C ₇ -C _S acyl radical; R ^H and R ^IV are the same or different and represent C 1 -C 4 alkyl radicals; or the 1,3-diethers in which the carbon atom at the 2-position belongs to a cyclic or polycyclic structure formed from 5, 6 or 7 carbon atoms and containing two or three double bonds.

Ethers of this type are described in published European patent applications 361493 and 728769.

Representative examples of said diethers are 2-methyl-2-isopropyl-1,3-dimethoxypropane, 2,2-diisobutyl-1,3,3-dimethoxypropane, 2-isopropyl-2-cyclopentyl-1,3-dimethoxypropane, 2-isopropyl -2-isoamyl-25-1,3-dimethoxypropane, 9,9-bis (methoxymethyl) fluorene.

The preparation of the catalyst materials is carried out in various ways. For example, MgCL adduct. nROH (especially in the form of spherical particles), where n is generally from 1 to 3 and ROH is ethanol, butanol or isobutanol, reacts with an excess of TiCl ₄ containing a compound capable of · · • · · · · · · · · · · · · · · · · · · · · · · · · · • • • • •

- 9 donate electrons. The reaction temperature is generally from 80 to 120 ° C. The solid is then isolated and reacted again with TlCl4 in the presence or absence of an electron donating compound and then separated and washed with hydrocarbon aliquots until the chloride ions disappear.

In the solid catalyst material, the titanium component, expressed as Ti, is generally present in an amount of from 0.5 to 10% by weight. The amount of electron donating compound that remains fixed on the solid catalyst component is generally 5 to 20 mol% relative to the magnesium halide.

The titanium compounds that can be used to produce the solid catalyst component are titanium halides and halogen alcoholates. The preferred compound is titanium tetrachloride.

The above reactions result in the formation of magnesium halide 15 in active form. Other reactions which cause the formation of magnesium halide in active form are also known in the literature, starting from magnesium compounds other than halides, for example magnesium carboxylates.

The active form of the magnesium halide in the solid catalyst component 20 can be recognized by the fact that the X-ray spectrum of the catalyst component does not contain the otherwise present maximum reflection intensity in the spectrum of unactivated magnesium halide (with specific surface area less than 3 m ² / g). is a halogen with a maximum intensity offset relative to the maximum intensity reflection position of the unactivated magnesium halide, or activation results in a maximum reflection intensity having a width at half the peak height at least 30% greater than the width at half the peak peak reflection; which appears in the spectrum of unactivated magnesium halide. The most active forms are those where the 4 * 4 * 4 * 4 · 4 · 4 · 4 · 4 · 4 · 4 · 4 · 4 · *

4 * ··· 4 ···

4 · · · · · · · · · · · ·

The above halo appears in the X-ray spectrum of the solid catalyst component.

Among the magnesium halides, magnesium chloride is preferred. In the case of the most active forms of magnesium chloride, the X-ray spectrum of the solid component of the halo catalyst is shown instead of the reflection that appears in the spectrum of unactivated chloride at 2.56 Å.

Alkylaluminum compounds used as cocatalysts include trialkylaluminum compounds such as triethylaluminum, triisobutylaluminum, tri-n-butylaluminum, and straight or cyclic aluminum alkyl compounds containing two or more aluminum atoms linked together via O or N atoms, or groups

SO4 or SO3.

The alkyl-aluminum compound is generally used in an amount such that the Al / Ti ratio is from 1 to 1000.

Compounds capable of donating electrons that can be used as external donors include aromatic acid esters such as alkyl benzoates, and especially silicon compounds containing at least one Si-OR bond, wherein R is a hydrocarbon radical.

Examples of silicon compounds are (tert-butyl) 2 Si (OCH 3) 2, (cyclohexyl) (methyl) Si (OCH 3) 2, (phenyl) 2 Si (OCH ₃ ) 2, and (cyclopentyl) 2 Si (OCH 3) 2. Preferably, 1,3-diethers of the above formulas may be used. If the internal donor is one of these diethers, the external donor may be omitted.

As mentioned above, the polymerization step can be carried out in at least two consecutive steps if components A) and B) are prepared in separate consecutive steps, each step except for the first step being operated in the presence of the polymer formed and the catalyst used. in the previous step. The catalyst is added only in the first step, but its activity is such that it is still active in all subsequent steps.

• 9 ··

999 999 9999 • 9999999999999

The order in which components A) and B) are prepared is not critical.

The degree of polymerization, which may be continuous or batch, is carried out by known methods in the liquid phase in the presence or absence of an inert diluent or in the gas phase or by methods using mixtures of liquid and gas phase. It is preferred to carry out the gas phase polymerization.

The reaction time, pressure and temperature with respect to the two steps is not critical, but it is best to use temperatures from 20 to 100 ° C.

The pressure may be atmospheric or higher. The molecular weight control is carried out using known regulators, in particular hydrogen.

The catalysts may be pre-contacted with small amounts of olefin (prepolymerization).

Specific examples of starting materials suitable for obtaining the materials of the present invention by degradation action and examples of a polymerization process suitable for producing said starting materials are described in the already published European Patent Applications 483523, 560326 and 674991.

The degradation action can be carried out in any manner under conditions known in the art effective in reducing the molecular weight of the olefin polymers.

In particular, it is known that the molecular weight of olefin polymers can be reduced by using heat (thermal degradation) preferably in the presence of free radical initiators such as ionizing radiation or chemical initiators.

Among the chemical initiators, organic peroxides are particularly preferred, examples of which are 2,5-dimethyl-2,5-di (t-butylperoxy) hexane and dicumyl peroxide.

The degradation action by chemical initiators can be carried out in conventional apparatuses generally used for polymer processing

3o in the molten state, such as especially single-screw or double-screw

- 12 extruders. It is preferred to operate in an inert atmosphere, for example a nitrogen atmosphere.

The amount of chemical initiator added to the starting material can be readily determined by one skilled in the art based on the value

MFR L (1) (i.e. MFR L values of the starting material) and desired MFR L (2) values (i.e. MFR L values of the finished material). This amount generally ranges from 100 to 700 ppm.

The degradation temperature is preferably in the range from 180 to 300 ° C.

The compositions of the present invention may also include additives commonly used in the art such as antioxidants, light and heat stabilizers, dyes and fillers.

Among the various applications afforded by the above properties, the materials of the present invention can be used in particular for the production of films and sheets.

Foils are generally characterized by a thickness of less than

100 µm, while sheets generally have a thickness greater than or equal to 100 µm. Both the films and the sheets may be monolayer or multilayer.

In the case of multilayer films or sheets, it comprises at least

2o one layer of the materials of the present invention. Each layer that does not contain the materials of the present invention may be composed of other olefin polymers such as polypropylene or polyethylene.

Generally speaking, the films and sheets of the present invention can be prepared by known methods such as extrusion and rolling. Specific examples of films containing materials of the present invention are those further described in the seal initiation temperature (S.I.T.) assay.

Further details are given in the following examples, which are given below

3o illustrate without limiting the present invention.

• • 44 4 4 • • 4 4 4 · 4 4 • 4 4 4 44 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 • • 4 4 44 4 4 4 4 4 4 4 4 • 4

DETAILED DESCRIPTION OF THE INVENTION

Examples 1 and 2 (comparative)

In the following Example 1, the starting material is prepared by sequential polymerization and this material is then subjected to degradation to obtain the finished material of the invention. For comparative purposes, a material having a welding initiation temperature of less than 100 ° C and an MFR L value comparable to that obtained in Example 1 by degradation is prepared directly by polymerization in Example 2.

The polymerization employs a solid catalyst component, a ZieglerNatt catalyst with high stereospecificity on a magnesium chloride support containing about 2.5% by weight of titanium and diisobutyl phthalate as an internal donor prepared analogously to the methods described in the published European patent application 674991.

Catalytic system and prepolymerization

Prior to introduction into the polymerization reactors, the solid catalyst component described above is contacted at -5 ° C for 5 min with trithylaluminum (TEAL) and dicyclopentyldimethoxysilane (DCPMS) at a TEAL / DCPMS weight ratio of about 4, and in such a quantity that the TEAL / molar ratio This is equal to 65.

The catalyst system is then prepolymerized by keeping the slurry in liquid propylene at 20 ° C for about 20 minutes before being fed to the first polymerization reactor.

- 14 ♦ 9 9 9 99 9 9 9 * *

9 9 9

9 9 9

9 9 9

9 • 99

Polymerization

In the first gas phase polymerization reactor, propylene / ethylene copolymer (component (A)) is produced by continuous feed with a constant flow of the prepolymerized catalyst system, hydrogen (used as molecular weight regulator) and propylene and ethylene monomers in the gaseous state.

The polymerization conditions, the molar ratio of the reagents and the composition of the copolymers obtained are given in Table 1.

The copolymer produced in the first reactor of 35% by weight of the total mixture in Example 1 and 40% by weight of the total mixture in Example 2 is continuously removed and, after removal of unreacted monomers, continuously injected into the second gas phase reactor together with quantitatively constant hydrogen and propylene streams; monomers of ethylene and 1-butene in the gaseous state.

The propylene / ethylene / 1-butene copolymer formed in the second reactor (component (B) is produced in an amount of 65% by weight relative to the total material in Example 1 and 60% by weight relative to the total material in Example 2. Polymerization conditions, reagent molar ratio and copolymer compositions are shown in Table 1.

The polymer particles exiting the second reactor are steam treated to remove reactive monomers and volatiles and then dried.

The polymer particles are then fed into a rotating drum where they are mixed with 0.05% by weight of paraffin oil ROL / OB 30 (with a density of 0.842 kg / l at 20 ° C according to ASTM 1298 and a drop temperature of -10 ° C according to ASTM D 97). 0.15% by weight of Irganox B 215 (prepared from approximately 66% by weight of tri [2,4-t-dibutylphenyl] phosphite and the remainder up to 100% by weight

- 16 * · · ·

tetrakis [methylene (3,5-di-t-butyl-4-hydroxyhydrocinnamate) j) and 0.05% by weight of calcium stearate.

300 ppm of Luperox 101 (2,5-dimethyl-2,5-di (η 5 -butylperoxy) hexane), which serves as a free radical initiator in the subsequent extrusion treatment, was also added to the starting material portion of the polymer particles of Example 1.

The polymer particles are then fed to a Berstorff ZE 25 twin screw extruder (screw length / diameter ratio: 33) and extruded under a nitrogen atmosphere under the following conditions:

Rotation speed: Extruder exit: Melting point:

250 rpm;

up to 20 kg / h;

200-250 ° C

The data relating to the polymeric materials in Tables 1 and 2 are obtained from measurements carried out on such extruded polymers. The data from Table 2 relates to the finished material of the present invention obtained by degradation treatment of the starting material of Example 1, i.e. extruding it with 300 ppm of tuperox 101 as mentioned above.

The data in the tables are obtained by the following test methods.

Molar ratios of input gases

It is determined by gas chromatography.

Content of ethylene and 1-butene in polymers

Determine by infrared spectroscopy.

• 9 · · • • • * • 9 • • · • • • 9 9 · * 9 9 9 • 9 9 9 9 • 99 9 9 9 9 9 • · 9 9 9 9 • • 9 9 • 9 9 9 · • 9 • • · 9 9

Melting index MFR L

Determine according to ASTM D 1238, condition L.

Melting point (Tm) and crystallization temperature (Tc)

It is determined by differential scanning calorimetry (DSC).

Fraction soluble in xylene

It is determined as follows:

2.5 g of polymer and 250 cm @ ^{3 of} xylene are placed in a glass flask equipped with a condenser and a magnetic stirrer. The temperature is raised over 30 minutes to the boiling point of the solvent. The clear solution thus obtained is kept under reflux with stirring for a further 30 min. The sealed flask was then stored in an ice / water bath for 30 min and a thermostatic water bath at 25 ° C for 30 min. The solid thus formed is filtered on a quick-filter paper. 100 cm ^{3 of the} filtered liquid is poured into a pre-weighed aluminum container which is heated on a hot plate in a stream of nitrogen to remove the solvent by evaporation. The vial is then kept in an oven at 80 ° C under vacuum until a constant weight is reached.

Hexane soluble fraction

It is determined by FDA 177, 1520, by suspending a 100 µm thick film of composition analyzed in excess hexane in an autoclave at 50 ° C for 2 hours. The hexane is then removed by evaporation and the dried residue is weighed.

Welding initiation temperature (S.I.T.)

It is determined as follows:

- 17 • 4 9 9 99 9 9 9 9 9

• 99 9 9 9 9

99 99 99

Preparation of film samples:

By extruding each test material in a single screw Collin extruder (screw length / screw ratio: 25), a 50 µm film was prepared at a film drawing speed of 7 m / min and a melting point of 210-250 ° C. Each film obtained was applied to a 1000 µm propylene homopolymer film with an isotactic index of 97 and an MFR L of 2 g / 10 min. The composite films are joined together in a Carver press at 200 ° C and a load of 9000 kg, which is held for 5 min.

The obtained laminates are stretched longitudinally and transversely, i.e. in two axes, by a factor of 6 on a TM Long film stretcher at 150 ° C to obtain a 20 µm thick film (18 µm homopolymer and 2 µm of test material).

2x5 cm samples were cut from the films.

Determination of S.I.T.

For each test, two of the above samples are folded in an arrangement adjacent to each other the layers of the respective test material. The composite samples are welded along one side by 5 cm with a Brugger Feinmechanik Sealer, model HSG-ETK 745. The welding time is 0.5 s and the pressure is 0.1 N / mm ² . The welding temperature increases for each welding, starting at a temperature about 10 ° C below the melting point of the test material. The welded specimens are allowed to cool and the non-welded ends are mounted on an Instron instrument and tested at a feed rate of 50 mm / min.

S.l.T. is the minimum welding temperature at which the weld will not break under a load of at least 2 N under the specified test conditions.

»· 4 9 99 9 9 9

9 9

9

99

9 9 9

9 9 9

9 9 9

99

Haze foil

Haze is determined on films of 50 prn of test material prepared as described for the S.I.T. The measurement is carried out on a 50 x 50 mm cut-out from the central region of the film.

A Gardner photometer with Hazemeter UX-10 turbidity meter equipped with a G.E lamp is used for the test. 1209 and filter C. Calibration of the instrument is performed with no sample present (haze 0%) and intermittent light measurement (haze 100%).

ío Shine foil

It is determined on the same samples as turbidity.

A Zehntner model 1020 photometer is used for the test. The calibration is performed at a 60 ° incidence angle on a standard glass of 96.2% and a 45 ° incidence angle on a standard glass of 55.4%.

Table 1

Examples 1 2 (comparative) 1. Reactor Temperature, ° C 70 70 Pressure, MPa 1,8 1.6 H2 / C3 ', mol. <0.01 0.04 7C ₂ C ₂ '+ C _3', Mol. 0.03 0.03 The polymer obtained C ₂ ,% 3.1 3.1 MFR L, g / 10min 0.54 5.0

- 19 · · φ »φ φ φ φ φ φ φ φ φ φ φ φ φ φ

9 9 9

9 9 9

9 99

Table 1 - continued

2. Reactor Temperature, ° C 65 65 Pressure, MPa 1.6 1.6 H ₂ / C ₃ , mol. 0,021 0.13 C ₂₇ C ₂ + C ₃ ', mol. 0.03 0.03 C47C4 '+ C ₃ ', mol. 0.17 0.17 Overall composition C _? /,% 4.0 4.0 c ₄ ; % 6.0 5.8 MFR L, g / 10min 0.98 4.4 Tm / Tc, ° C 136 / 88.7 134 / 87.7 X.S.,% 11.9 15.1 H.S.,% 3.9 7.0 C ₂ 'in XI,% 3.2 - C ₄ 'in XI,% 5.6 - C ₂ 'in XS,% 10.9 - C ₄ 'in X.S.,% 8.9 - S.I.T., ° C 97 97 Turbidity,% 11.9 1.9 Gloss,% o 66.2 80.0

- 20 9999 »9 9 · 9

9 · 9

9 9 9

9 9 9

9

99

9 9

Table 2 (Example 1)

Overall composition c ₂ ; % 4.0 C ₄ ',% 6.0 MFR L, g / 10min 5.7 Tm / Tc, ° C 137 / 89.7 X.S.,% 11.9 H.S.,% 3.8 C ₂ 'in XI,% 3 C ₄ 'vX.I.,% 4.6 C / vX.S.,% 6.6 C ₄ 'in XS,% 9.8 S.I.T., ° C 93 Turbidity,% 0.1 Gloss,% o 88.5

Notes on tables:

C2 = ethylene; C3 = propylene; C4 = 1-butene; X.S. = fraction soluble in xylene; H.S. = hexane soluble fraction; X.l. = fraction insoluble in xylene; all percentages (except turbidity) are percent by weight.

The comparison between the data in Table 2 and the data in Example 2 (comparative example) presented in Table 1 shows that the equilibrium

The low solubility and optical properties of the materials of the present invention are not achieved if comparable MFR L values are obtained directly in the polymerization.

Claims (5)

PATENT CLAIMS 1) preparing the starting material by polymerizing monomers in at least two consecutive steps, wherein components A) and B) are prepared in separate consecutive In 25 steps, each step is carried out in the presence of the polymer formed and the catalyst used in the previous step, and the molecular weight regulator is metered in amounts to obtain an MFR L (1) for the starting material of 0.3 to 5 g / 10 min. ; - 23 · * 23 23 23 23 23 9 23 23 23 23 23 23 23 23 23 23 23 23 23 23 23 23 9 · 99 9 9 · 9 9 · 99 1. A material comprising a crystalline propylene copolymer of s 5 MFR L values from 2 to 15 g / 10 min, comprising: A) 20 to 80% by weight of one or more propylene copolymers selected from (A1) propylene / ethylene copolymers containing 1-7% by weight of ethylene; (A 2) propylene copolymers with one or more C ₄ -C 8 alpha-olefins containing 2 to 10% by weight of C4C8 alpha-olefins; (A 3) copolymers of propylene with ethylene and one or more C ₄ -C 8 alpha-olefins, containing 0.5 to 4.5% by weight of ethylene and 2 to 6% by weight of C4-C8 15 alpha-olefins, provided that the total content of ethylene and C4-C8 alpha-olefins in the group (A 3) is equal to or less than 6.5% by weight; B) 20 to 80% by weight of one or more propylene copolymers selected from group (B1) copolymers 20 propylene with one or more C4-C8 alpha-olefins, containing from more than 10 wt% to 30 wt% _C4 -CS alpha-olefins; (B 2) copolymers of propylene with ethylene and one or more C4-C8 alpha-olefins containing 1 to 7% by weight of ethylene and 6 to 7% by weight of ethylene 25 15% by weight of C4-C8 alpha-olefins; wherein said MFR L values, i.e. MFR L (2), are obtained by exposing the starting material containing the same components A) and B) in the above proportions, but with MFR L values, i.e. MFR L (1) of from 0.3 to 5 g / 10 min degradation, with a ratio of MFR L (2) to MFR L (1) of from 2 to 20. - 22 ♦ ♦ · 4 4 4 4 4 4 2) the starting material obtained in step 1) is subjected to a degradation treatment to obtain MFR L (2) values for the final material from 3 to 15 g / 10 min, preferably from 4 to 10 g / 10 min, with a degradation ratio expressed as the ratio MFR L (2) / MFR L (1) from 2 to 20. A material comprising the crystalline propylene copolymer of claim 1, comprising: A) 20 to 60% by weight propylene / ethylene copolymer 5 containing 1-7% by weight of ethylene; B) 40 to 80% by weight of a copolymer of propylene with ethylene and one or more C ₄ -C ₈ alpha-olefins containing 1 to 7% by weight of ethylene and 6 to 15% by weight of C ₄ -C ₈ alpha-olefins; wherein the total amount of ethylene in the material is 1 to 5% by weight and the total amount of C ₄ -C ₈ alpha-olefins in the material is 2.4 to 12% by weight. 3. Single-layer or multi-layer foil or board, 15, wherein the at least one layer comprises the crystalline propylene copolymer containing material of claim 1. 4. A method of making a material comprising a crystalline copolymer 20. The propylene of claim 1 comprising the following steps: 4 4 44 4 4 4 4 44 444 • 44 4 • 4 4 • 4 4 4 4 · The method of claim 4, wherein the degradation ratio is from 3 to 15.