AU669503B2

AU669503B2 - Impact-resistant polyolefin molding composition

Info

Publication number: AU669503B2
Application number: AU31848/93A
Authority: AU
Inventors: Bernd Bachmann; Volker Dolle; Andreas Winter
Original assignee: Hoechst AG
Current assignee: Hoechst AG
Priority date: 1992-01-18
Filing date: 1993-01-15
Publication date: 1996-06-13
Anticipated expiration: 2013-01-15
Also published as: DE59308622D1; EP0552681A1; TW259804B; CA2087417A1; ZA93263B; ES2116357T3; KR100269835B1; RU2107701C1; AU3184893A; KR930016488A; ATE166909T1; EP0552681B1; JP3328674B2; JPH05247277A

Abstract

A polyolefin moulding composition essentially comprising from 20 to 99 % by weight, based on the moulding composition, of an isotactic polyolefin containing no atactic polymer chains and from 1 to 80 % by weight, based on the moulding composition, of a rubber having a glass transition temperature of below -20 DEG C is distinguished by high impact strength and hardness even at low temperatures.

Description

I/U/01 1 28 591 Regulation 32(2)

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT D r o n r oa r sir 91 lr so a Application Number: Lodged: it o sris a ~r r ,s ,r rrir Invention Title: IMPACT-RESISTANT POLYOLEFIN MOLDING COMPOSITION The following statement is a full description of this invention, including the best method of performing It known to :-US HOECHST AKTIENGESELLSCHAFT HOE 92/F 008 Dr. LO/bs Description Impact-resistant polyolefin molding composition The invention relates to a polyolefin molding composition of an isotactic olefin homopolymer and/or olefin copolymer and a rubber, which has a high hardness and a high impact resistance even at low temperatures.

Impact-resistant polyolefin molding compositions are o°o, known in principle. They are prepared by mixing, for 10 example, polypropylene and a rubber, such as, for example, ethylene/propylene rubber (EPM) or ethylene/ ,o propylene/diene rubber (EPDM), in the melt (Angew.

I""00 Makromol. Chem. 185/186 (1991) 97; and Polymer, 28 (1987) 47).

15 According to the prior art, the polypropylene used comprises atactic polypropylene (APP) to the extent of at least 2 10% by weight and polypropylene chains of widely varying chain length 5 10) to the extent of 90 98%.

20 Alternatively, a propylene copolymer which also comprises, in addition to APP, polypropylene chains and polymer chains of the comonomer having the build-up described above, propylene copolymer chains of varying copolymer contents and likewise varying chain lengths is also used as the polypropylene component.

Moreover so-called reactor blends are known. These are composed of APP, polypropylene and polymers of the comonomer of varying chain length, as well as of propylene comonomer chains of varying chain length and comonomer contents. They are prepared directly in the polymerization reactor in one or more polymerization .i i -r_ i I. ~^^~--~'-Zrr=P-rCFuslmwuPupP1P1 2 steps.

All these molding compositions have the common feature that they have only an unsatisfactory rigidity/hardness at the desired high impact resistance.

There was thus the object of discovering a molding composition which does not have the adverse properties known from the prior art.

Surprisingly, it has now been found that if polymers and copolymers which are free from atactic polymer chains (atactic polyolefin; called APO) and have a homogeneous 0 molecular weight distribution (XM/M, is preferably less o "0 than 5) are used, the abovementioned disadvantages can be avoided.

o o The invention thus relates to a polyolefin molding composition essentially comprising 20 to 99% by weight, based on the molding composition, of an isotactic polyolefin which contains no atactic polymer chains and 1 to by weight, based on the molding composition, of a rubber having a glass transition temperature below The APO-free isotactic polyolefin to be used for the preparation of the polyolefin molding composition according to the invention is a polymer having a narrow molecular weight distribution M/Mn of 5, preferably 3.5, and a uniform chain build-up. Uniform chain buildup is understood as meaning a random distribution of building defects and/or comonomers in the polymer chain.

APO-free isotactic polyolefins are to be understood as meaning those polyolefins which essentially comprise no atactic polymer chains. These are products (homo- and copolymers) which are prepared using highly stereospecific metallocene/aluminoxane catalyst systems.

RA Corresponding processes are known and are described, for l V i.

c example, in EP-A 302,424, EP-A 336,127, EP-A 336,128 and DE-P 40 35 886.0. The isotactic polyolefins prepared by the processes mentioned comprise only very small contents, if any, of atactic polymer chains. As a rule, this content is less than 1% by weight.

In principle, it is also possible for polyolefins which have been prepared using conventional Ziegler catalysts (MgCl 2 /TiCl 4 /electron donor/AlEt 3 and comprise noticeable APO contents to be converted into polyolefins which are APO-free and therefore according to the invention by extraction of the APO contents with a hydrocarbon.

However, because of the associated involved process, i.e.

for reasons of cost, such a procedure is not very approo 9 priate.

.o 15 The isotactic polyolefin to be used according to the a o invention either is an olefin homopolymer having a molecular weight distribution M1/Mn 5, preferably and an isotacticity index (II) of at least 85%, or an olefin copolymer having an Mw/Mn of 5, preferably and an isotacticity index of at least 85%, or the polyolefin is composed of an olefin homopolymer and an olefin copolymer in which the isotacticity index is at least and M/Mn of the components is 5, preferably If the olefin polymer is an olefin homopolymer, it comprises units of an olefin having at least 3 carbon atoms, of the formula R a -CH=CH-Rb, in which Ra and Rb are identical or different and are a hydrogen atom or an alkyl radical having 1 to 10, preferably 1 to 6 carbon atoms, or Ra and Rb, with the carbon atoms joining them, form a ring having 4 to 22 carbon atoms. Preferred olefins are propylene, 1-butene, 4-methyl-l-pentene, 1-hexene, pentene and norbornene. Propylene is particularly preferred, i.e. the molding composition according to the invention comprises, in particular, polypropylene.

4 If the olefin polymer is an olefin copolymer, it comprises olefin units defined above for the homopolymer and having an isotacticity index of at least 85% to the extent of 99.5 to 50, preferably 99 to 70% by weight, and units of ethylene and/or another olefin of the above definition as the comonomer to the extent of at least to 50, preferably 1 to 30% by weight. The comonomer is incorporated randomly with a high regularity. Preferred comonomers are ethylene, 1-butene, 4-methyl-l-pentene, 1-hexene, norbornone or pentene. Particularly preferred olefin comonomers comprise propylene units and ethylene comonomer units.

If the polyolefin comprises a mixture of olefin homopolymer and olefin copolymer, the olefin homopolymer has the composition described above. The olefin copolymer com- .oo prises an olefin as defined above for the olefin homopolymer to the extent of 20 to 90% by weight, preferably to 90% by weight, and units of ethylene and/or at least one olefin as defined above for an olefin copolymer 20 to the extent of 80 to 10% by weight, preferably 60 to by weight. The comonomer is preferably incorporated randomly. The content of olefin homopolymer in the total polyolefin composition in this case is 20 to 99% by weight, preferably 40 to 95% by weight, and the content 25 of olefin copolymer is 80 to 1% by weight, preferably to 5% by weight.

If it comprises two different polyr;ar components, the polyolefin according to the invention is particularly Spreferably composed of 40 to 95% by weight of polypropylene (based on the total amount of polyolefin) having an isotacticity index of at least 85%, and 60 to by weight (based on the total amount of polyolefin) of olefin copolymer comprising 40 to 90% by weight of propylene units and 60 to 10% by weight of ethylene units (in each case based on the total amount of olefin copolymer).

L i 5 5 The molding composition according to the invention comprises the isotactic olefin polymer in an amount of to 99% by weight, preferably 40 to 95% by weight.

1 to 80, preferably 5 to 60% by weight of the molding composition according to the invention is a rubber having a glass transition temperature below -20°C. Suitable rubbers are, for example, styrene/butadiene rubbers, silicone rubbers, ethylene/propylene rubbers (EPM) or ethylene/propylene/diene rubbers (EPDM). EPM and EPDM rubbers can addit.inally also comprise up to 40% of polyethylene. 1,4-Hexadiene, norbornadiene or cyclopentadiene can be present in an amount of up to 10% by weight, based on the total amount of rubber, as the diene component.

o a S. 15 The content of ethylene and propylene is not limited, as long as a glass transition temperature of the amorphous components of less than -20°C is achieved.

A typical composition for commercially available EPM rubbers is, for example, 10-60% by weight of propylene 20 units and 90-40% by weight of ethylene units. Of the ethylene units, 0-40% by weight are a pure polyethylene content, and the remainder forms a copolymer content, together with the propylene.

EPDM rubbers are of corresponding composition, but 1-10% by weight of a diene of the abovementioned type is also additionally incorporated in the copolymer content, in addition to propylene and ethylene. The melt viscosity of typical EPM and EPDM rubbers is between 0.5 and 300 g/10 minutes (MFI 230/5).

The Mooney viscosity (measured at 121 0 C, ML) is typically between 20 and 80. The tensile stress at 60% elongation is typically 10-300 psi (pounds/square inch, 1 psi 6894.8 kg/m.second 2 1 Pa).

L L I LI---i-s- 6 Rubbers which can typically be used are on the market, for example, under the currently existing commercial names Vistalon, Exxelor (Exxon Chemicals), Dutral (Dutral Nordel (DuPont) or Buna (Veba).

In audition to the isotactic olefin polymer and the rubber, the molding composition according to the invention can also contain the customary additives, for example stabilizers, antioxidants, UV absorbers, light protection agents, metal deactivators, free radical scavengers, fillers and reinforcing agents, compatibilizing agents, plasticizers, lubricants, emulsifiers, pigments, optical o brighteners, flameproofing agents, antistatics and O o blowing agents.

The molding composition according to the invention can be prepared by the methods customary in plastics processing for mixing polymers and additives.

One possibility is sintering in a high-speed mixer, if ,o all the constituents of the molding composition are pulverulent.

oO0. 20 Another possibility is ,-he use of an extruder having mixing and kneading organs on the screw.

Finally, kneaders such as are employed in the rubber and synthetic rubber industry are also suitable mixing machines.

The mixing temperature depends on the particular composition of the molding composition and can be determined by simple routine experiments.

The molding composition according to the invention is distinguished by a high hardness, in combination with high impact resistance, in particular even at temperatures below 0°C. In general, this molding composition l -e -J i I 7 can be used in the form of extruded, injection molded, foamed or blown moldings in all instances where high rigidity, hardness, dimensional stability and scratch resistance in combination with high impact resistance, tear strength and flexural strength are desired.

It can be used in automobile construction, for example, for side lining strips, spoilers, seals, fender linings, bumper materials, truck and tractor fenders, scratchresistant automobile interior fittings or hub caps.

The molding composition according to the invention .furthermore is also suitable, for example, for the production of tear-resistant films, membrane filters, O o0 fibers and filaments.

The following examples are intended to illustrate the invention in more detail.

II isotacticity index (by 1 C-NMR spectroscopy) nis o average isotactic chain length (by 1

C-NMR)

np average polyethylene block length VN viscosity number, measured at 135"C as a 20 0 1% strength solution in decahydronaphthalene in a capillary viscometer MFI 230/5 melt index at 230"C, 5 kg load, in accordance with DIN 53 735 EM/Mn polydispersity (measure of the chain length distribution) Determination of the melting points by DSC BIH ball indentation hardness (in accordance with DIN 53 456, pressed sheets 4 mm thick) aK notched impact strength according to DIN 53 453, measured on standard small bars x 6 x 4 mm), taken from pressed sheets, with a V notch (flank angle 45", notch depth 1.3 mm, notch radius 1 mm).

c

F-

8- A ZSK 28 twin-screw extruder (Werner Pfleiderer) was used for the preparation of the molding compositions.

Example 1 A molding composition comprising 90% by weight of isotactic polypropylene, based on the total molding composition, and 10% by weight of a rubber having the following composition was prepared by extrusion: 35.8% by weight of propylene units and 64.2% by weight of ethylene units; 40.4% by weight of the rubber composition was polyethylene and 59.6% by weight was an ethylene/ propylene copolymer (EPM) comprising 60.0% by weight of ~o propylene units and 40.0% by weight of ethylene units.

The MFI 230/5 of the rubber was 2 g/10 minutes, the viscosity number (VN) was 236 cm 3 the DSC melting point was 131°C and the DSC glass transition temperature was -56 0 C. The isotactic polypropylene used had an 04O isotacticity index (II) of 96.0%, an ni.. of 49, an MFI 230/5 of 32 g/10 minutes and a melting point of 148°C; further data were: M, 190,000 g/mol; M /N 2.2, VN 174 cm 3 no APO contents extractable with ether or heptane.

:9 kg of the isotactic polypropylene powder were mixed with 1 kg of the rubber, and the mixture was stabilized against chemical degradation under extrusion conditions with 10 g of pentaerythrityl tetrakis[3-(3,5-diLt-butyI- 4 4-hydroxyphenyl)propionate]. The temperatures established in the five heating zones of the extruder were 120 0

C

(intake), 150°C, 190 0 C, 185 0 C and 180°C (die plate). The extruder screw was operated at 300 revolutions per minute; the melt temperature of the mixture in the extruder was 210 0

C.

The following data were measured on the molding composition thus produced:

I.

0-9- MFI (230/5) 31 g/10 minutes; VN 168 cm 3 /g; BIH 70 Nmm- 2 aKv 10.1 mJmm 2 (23 0

C);

5.4 mJnmfm 2 and 4.3 mJmm nf 2 (-20 0

C).

Melting point (DSC) 128 and 148°C, glass transition temperature Tg -56°C.

Comparison Example A Instead of the APO-free (here APP-free; APP atactic polypropylene) isotactic polypropylene of narrow distribution according to the invention, a polypropylene having the following data was employed under the same conditions as in Example 1: MFI (230/5) 27 g/10 minutes; VN 220 cm 3 /g; oo 312,000 g/mol, 8.5; APP content by heptane extraction: 2.3% by weight.

0 o The molding composition thus obtained had the following data: MFI (230/5) 24 g/10 minutes; VN 245 cm 3 /g; BIH Nmm- 2 aKv mJmm 2 B o o Melting point (DSC) 128/164°C, glass transition temperature Tg -56°C.

0 I 0 0 Examples 2 4; Comparison Examples B D The procedure was as in Example 1 (Examples 2 4) or as in Comparison Example A (Comparison Examples B but j instead of 10% of rubber 15% (Example 2; Comparison Example 25% (Example 3, Comparison Example C) and *1 (Example 4, Comparison Example D) of rubber was employed.

The results are summarized in Table 1.

I

00? 0 0 0 Trble I Example MFl (230/5) VN BIH a K" [Mjinnf 2 Melting point Tg min) [CM 3

[NMM-

2 (DSC, (DSC, 'C 23 0 C 0 0 C -20 0

C

2 27 175 65 13.8 8.1 6.0 128/146 -57 VB 22 236 129/164 3 23 178 54 31.9 19.7 13.5 129/148 -58 VC 19 239 129/162 -57 4 19 179 44 39.1 31.0 16.4 130/147 -57 VD 16 239 129/160 -54 (V Comparison Example) 11 Examples 5 8 Examples 1 4 were repeated, but a product having the following data was used as the polypropylene according to the invention: II 96.1%; nis, 53; MFI 230/5) 4 g/10 minutes; melting point 151*C, M, 369,500, M1/Mn VN 293 cm 3 no APP contents extractable with ether or heptane.

This polypropylene was processed by extrusion with 10% by weight (Example 15% by weight (Example 25% by weight (Example 7) and 40% by weight (Example 8) of the rubber to give molding compositions having the data summarized in Table 2.

0 0 0 Comparison Examples E H The procedure was as in Examples 5 to 8, but a polypropylene which is not according to the invention and has the following data was used: MFI (230/5) 9 g/10 minutes; VN 302 cm 3 /g; M, 288,000 g/mol; M/M, 5.7; APP by heptane extrac- S 20 tion: 2.7% by weight.

The molding compositions thus obtained, VE VF VG and VH having a 40% rubber content, had the data summarized in Table 2.

I

.1 i 000 0 0 0 Table 2 Example MFI (230/5) VN BIH aKV [mirnnf 2 Melting point Tg min] [CM 3 lg] [Nlmmf 2 23 0 C 0 0 C -20 0 C (DSC, OC (DSC, 0

C)

4 263 67 18.2 7.5 3.5 130/152 VE 8 260 62 13.5 7.0 3.2 129/164 -56 6 5 258 60 26.2 10.7 5.0 129/151 -57 VF 9 257 56 24.2 8.5 3.7 128/162 7 4 254 53 38.5 24.9 15.2 129/151 -56 VG 9 261 48 38.6 23.5 12.7 129/162 -56 8 4 252 43 41.9 40.9 30.5 130/152 -57 VH 7 255 35 41.4 38.3 30.3 128/160 -56 13 Example 9 Example 3 was repeated, but a product having the following data was used as the polypropylene according to the invention: II 96.4%, nis o 60; MFI (230/5) 100 g/10 minutes; Melting point 148"C, M, 154,500 g/mol, M/M 2.2; VN 146 cm 3 no APP contents extractable with ether or heptane.

The following data were measured on the molding composition prepared by extrusion with the rubber: MFI (230/5) 79 dg/minutes; VN 170 cm3/g; BIH 72 Nmnm 2 a, 28.6 17.5 and 8.7 mJmm 2 0 Example 00 o0 Example 3 was repeated, but an ethylene/propylene copolymer having the following composition and properties was used as the polyolefin according to the invention: Ethylene content incorporation of ethylene with an S...average ethylene block length of nPE 1.2, i.e. the predominant ethylene content is incorporated in isolated units. The II of the propylene sequences was 96.8%.

i MFI (230/5) 7.0 g/10 minutes; VN 289 cm 3 /g; 1. M, 402,000 g/mol, M,/Mn No APP contents extractable with ether or heptane.

25 The following data were measured on the molding composi- Stion prepared by extrusion with the rubber: MFI (230/5) 3.5 g/10 min, VN 272 cm 3 /g; BIH 50 Nmm- 2 av 45.7 27.9 and 18.4 mJmm 2 t 14 Example 11 Example 3 was repeated, but an ethylene/propylene block copolymer which was prepared in two stages and had the following composition and properties was used as the polyolefin according to the invention: 12.5% ethylene content; fractionation of the copolymer showed a composition of 76% of polypropylene having an II of 96.8% and 24% of an ethylene/propylene copolymer with an ethylene content of 52%, the ethylene being incorporated both as isolated units and in block form.

MFI (230/5) 4.9 g/10 minutes; VN 326 cm 3 /g; M, 407,000 g/mol, Mw/M n 3.1.

SNo APP contents extractable with ether or heptane.

The following data were measured on the molding composi- S 15 tion prepared by extrusion with the rubber: MFI (230/5) 3.4 g/10 minutes; VN 298 cm 3 /g; BIH 39 Nmn- 2 aK,: no fractures of the test specimen down to -40 0

C.

VV

t n a it

Claims

4-198 5:37 PM ;WATERMARK 1890;#/0 THE CLAIM -DEFINING THE ]NVENIO ARE AS FOLLOWSI: 1. A polyolefin molding composition essentially comprising 20 to 99% by weight, based on the molding composition, of an Isotactic polyolefin which contains no atactic polymer chains, the is-otactic polyolefin having an isotacticity index of at least 860% and a molecular weight distribution Mw/Mn Of less than and 1 to 80% by weight, based on the molding composition, of a rubber having a glass transition temperature below -20 0 C- 2. A molding composition as claimed in claim 1, wherein the isotactic polyolefin is an olefin homopolymer and comprises units of an olefin having at idetialor iferntand are a hydrogen atom or Ci-Cio-alkyl, or R~ and Rb, with the atoms joining them, form a ring having 4 to 22 carbon atoms. 3. A mnolding composition as claimed in claim 1 or 2, wherein the isotactic polyolpefin is polypropylene. 0 4. A molding composition as claimed In claim 1, wherein the Isotactic polyolefin is an olefin copolymer which comprises units of an olefin having at least 3 carbon atoms, of The formula Ra-CH=CH-Rb, in which Ra and Rb are 0 Identical or different and are a hydrogen atom or CI-Cio-alkyl, or Ra and Rb, Ij withi the atoms joining them, form a ring having 4 to 22 carbon atoms, and U having an isotacticity index of at least 85% to the extent of 99,.5 to 50% by weight, and units of ethylene and/or an olefin of the formnula. Ra-CH-CH-Rb to the extent of 0.5 to 60% by weight. A molding composition as claimed in claim 4, wherein the olefin copolymer is an ethyl ene/propylene copolymer. 5:P M ;VIA T ERM API '5138198010;# 1$
6. A molding composition as claimed in claim 1, wherein the isotactic polyolefin is a mixture of 20 to 99% by weight of an olefin homopolyrner which comprises units of an olefin having at least 3 carbon atoms, of the formula Ra--CH=CH-19b, in which Ra and Rb are identical or different and are a hydrogen atom or Cj-Cio-alkyI, or Ra and Rb, with the atoms joining thern, for a ring having 4 to 22 carbon atoms, and having an isotacticity index of at least and 80 to 1% by weight ci an olefin copolymer wM~cih comprises units of an olefin having at least 3 carbon atoms, of the formula Ra-CH=CH-Rb, in which Ra and Rb are identical or different and are a hydrogen atom or 0 1 -Clo-alkyl, or Ra and Rb, with the atoms joining them, form a ring having 4 to 22 carbon atoms, and having arn isotacticity index of at least .000085% to the extent of 20 to 90%1/ by weight, and units of ethylene and/or :..00ianother olefin of the formula Ra-CH=CH-Rb to the extent of 80 to 10% by weight.
7. A molding composition as claimed in any one of claims 1 to 6, which 04: additionally comprises stabilizers, antioxidants, UV absorbers, light protection agents, metal deactivators, 'free radical trapping agents. fillers and reinforcing agents, compatibilizing agents, plasticizers, lubricants, emulsifiers, pigments, p optical brighteners, flameproofing agents, antistatics or blowing agents. S The use of a molding composition as claimed in any one of claims 1 to 7 for the production of moldings. "T R L4 I K 4-19--98 5:37 PMI ;WATERMARK B1960:C;# 7/10 17
9. A molding which can be produced from a molding composition as claimed in any one of claims 1 to 7. DATED this 19th day of April, 1996. HO0ECHST AIj1IENGaEj9ELL HMAE. WATERMARK PATENT TRADEMARK ATTORNEYS 290 BURWOOD ROAD HAWTHORN VICTORIA 3122 AUSTRALIA KJS:C.JHL VAX doc 07 AU3184893.WPC *105 00 00 00 0 00 0 0 00 0 0 0 0000 0 00 0 4 HOE 92/F 008 Abstract of the disclosure: Impact-resistant polyolefin molding composition A polyolefin molding composition essentially comprising to 99% by weight, based on the molding composition, of an isotactic polyolefin which contains no atactic polymer chains, and 1 to 80% by weight, based on the molding composition, of a rubber having a glass transition temperature below -20 0 C is distinguished by a high impact resistance and hardness, even at low temperatures. oac 0 o 0 0 0 tt 0 0 4