WO1993020145A1

WO1993020145A1 - A polymer composition comprising a mixture of a crystalline or semi-crystalline polyolefin and a polymer based on vinyl-aromatic and dicarboxylic acid anhydride monomer units and a compatibiliser

Info

Publication number: WO1993020145A1
Application number: PCT/NL1993/000069
Authority: WO
Inventors: Reinoldus Jozef Maria Borggreve; Johannes Hermanus Grimberg; Cornelis Eme Koning
Original assignee: Dsm N.V.
Priority date: 1992-03-31
Filing date: 1993-03-25
Publication date: 1993-10-14
Also published as: AU3908093A; NL9200602A

Abstract

A polymer composition containing a crystalline or semi-crystalline polyolefin A, a polymer B based on vinyl-aromatic monomer units and dicarboxylic acid anhydride monomer units, and a compatibiliser. The compatibiliser is a functionalised polyolefin A or a functionalised polymer B.

Description

A POLYMER COMPOSITION COMPRISING A MIXTURE OF A CRYSTALLINE OR SEMI-CRYSTALLINE POLYOLEFIN AND A POLYMER BASED ON VINYL AROMATIC AND DICARBOXYLIC ACID ANHYDRIDE MONOMER UNITS

AND A COMPATIBILISER

The invention relates to a polymer composition comprising a mixture of a crystalline or semi-crystalline polyolefin (A) and a polymer (B) based on vinyl-aromatic an dicarboxylic acid anhydride monomer units, and a compatibiliser. In this context and below a compatibiliser is understood to be a compound which improves the compatibility of A and B and is present predominantly at th interface of the polyolefin A and the polymer B.

A polymer composition of this type is known from O-A-9005759. In O-A-9005759 a polymer mixture of a crystalline or semi-crystalline polyolefin and a second polymer, such as a copolymer of styrene and maleic anhydride, and a compatibiliser is described. According to this publication, the compatibiliser is a block copolymer o a vinyl-aromatic compound and a conjugated diene or partially hydrogenated derivatives thereof.

It is known from JP-A-63-205,341 to use styrene- containing rubber-like copolymers as compatibilisers in polymer compositions consisting of polypropene and styrene/maleic anhydride copolymers.

A disadvantage of such polymer compositions is, however, that the impact strength/rigidity combination (Izod vs. Modulus of elasticity) is poor, as a result of which the polymer compositions are unsuitable for use in structural moulded components which are used in, for example, cars and furniture.

The object of the invention is to provide a polyme composition of a crystalline or semi-crystalline polyolefin A and a polymer B based on vinyl-aromatic monomer units and dicarboxylic acid anhydride monomer units, which has a good impact strength/rigidity combination. A further advantage of the polymer composition according to the invention is that the said composition is free from delamination.

This is achieved owing to the fact that the polymer composition contains as compatibiliser a functionalised polyolefin A or a functionalised polymer B.

A functionalised polyolefin A or polymer B is understood to be: a polyolefin A or a polymer B which contains groups which are compatible or reactive with, respectively, the polymer B or the polyolefin A. The functionalised polyolefin A is a polyolefin which contains one or more functional groups, such as:

- a hydroxyl group,

- a thiol group,

- an amine group, - an amide group,

- an epoxide group,

- an oxazoline group,

- an isocyanate group or

- an alkoxide group. Preferably, the functionalised polyolefin A contains one or more oxazoline groups, one or more isocyanate groups or one or more amine groups.

The functionalised polymer B contains one or more linear or branched alkyl groups with 10-200 carbon atoms. The polymer composition usually contains 0.1-40% by weight of the compatibiliser, based on the sum of polyolefin A, polymer B and compatibiliser. Preferably, the polymer composition contains 0.1-20 parts by weight of the compati¬ biliser. The amount of compatibiliser which is added, can proportionally lower the amount of the polyolefin A in the polymer composition if the compatibiliser is a functionalised polyolefin A, and can proportionally lower the amount of polymer B in the polymer composition if the compatibiliser is a functionalised polymer B. The functionalised polyolefin A can, for example, be prepared starting from a polyolefin grafted with a dicarboxylic acid or anhydride, like maleic anhydride or acrylic acid. Such a grafted polyolefin preferably contains 0.01-10 parts by weight of anhydride or acid groups. Preferably, the polyolefin is grafted with maleic anhydride or acrylic acid and contains 0.1-7 parts by weight of malei anhydride groups or acrylic acid groups. The polyolefin grafted with an anhydride or with an acid, can thereafter b reacted with one or more of the compounds listed below, in order to obtain the functionalised polyolefin A. The compound to be used contains 2 or more: - hydroxyl groups,

- thiol groups,

- amine groups,

- amide groups,

- epoxide groups, - oxazoline groups,

- isocyanate groups.

The compound can also be an alkoxide of a metal from groups 4-13 of the Periodic System of the Elements (Handbook of Chemistry and Physics, 70th Edition, CRC Press, 1989-1990). Examples of such compounds are: 1,3-phenylene- bisoxazoline, 1,4-phenylene diamine, 1,3-phenylene diamine, methane-diphenyl diisocyanate, tetrabutyl titanate and ethanolamine.

During these reactions preferably at least 70% of the anhydride or acid groups of the grafted polyolefin are reacted. Crosslinking of the functionalised polyolefin should be avoided. Particularly prefered, 100% of the anhydride or acid groups are converted.

The functionalised polyolefin A can also be prepared by grafting non-functionalised polyolefin A with for example hydroxy ethyl methacrylate, glycidyl methacrylate, acrylamide, isopropenyloxazoline and dimethylmethaisopropenyl benzyl isocyanate.

The functionalised polymer B is, for example, synthesised by grafting polymer B with a compound which contains a linear or branched alkyl group with 10-200 carbon atoms and having a terminal functional group which is able to react with the dicarboxylic acid anhydride groups in polymer B. Preferably, 20-90% of the dicarboxylic acid anhydride units are converted.

Polymer B can be grafted with a linear or branched alkyl compound containing as the terminal functional group:

- a primary or secondary amine group,

- a primary alcohol group,

- a primary thiol group,

- an oxazoline group, - an epoxide group and/or

- an isocyanate group.

These compounds are, for example: 1-dodecylamine, 1-octa- decylamine, 1-nonadecyl alcohol, epoxydodecane, OLCv. 1200^R from Chevron (an amine-terminated polybutene having about 70 carbon atoms).

When grafting polymer B with an epoxide compound it is usually necessary to use an activator, such as an imida- zole, a guaternary ammonium salt or a tertiary amine.

Preferably, a compound which contains a linear or branched alkyl group with 10-200 carbon atoms and a primary amine as functional group is used as the compound for grafting polymer B.

The grafting reactions are performed by known methods for a person skilled in the art. Crystalline or semi-crystalline polyolefins A which can be used in a polymer composition according to the invention are homopolymers, copolymers or terpolymers or mixtures thereof. Polymers of α-olefins are preferably used and these α-olefins generally have 2 to 20 carbon atoms. The use of polymers of α-olefins having 2-6 carbon atoms is particularly preferred.

The crystalline or semi-crystalline polyolefins A are derived from α-olefins, such as ethene, propene, 1- butene, 1-pentene, 4-methyl-l-pentene, 1-octene, 1-decene, 4-ethyl-l-hexene, etc. Examples of particularly suitable polyolefins are: low density polyethylene, high density polyethylene, linear low density polyethylene, ultra-low density polyethylene, polypropylene, (high and low density) poly(l-butene) , poly(4-methyl-l-pentene) , ethylene/propylen copolymers and copolymers of ethylene and/or propylene with other copolymerisable monomers, such as ethylene/1-butene copolymer, ethylene/vinyl acrylate copolymer or ethylene/vinyl acetate. Polymers and copolymers of halogenated olefins.can also be used.

An amount of 30-95 parts by weight of polyolefin A is present in the polymer composition, based on the sum of polyolefin A and polymer B. The amount of polyolefin A is preferably 60-80% by weight. The amount of polyolefin A in the polymer composition can proportionally be lowered when functionalised polyolefin A is used as compatibilizer.

Polymer B comprises vinyl-aromatic monomer units and dicarboxylic acid anhydride monomer units. Suitable vinyl-aromatic monomers for use in the polymer B are, for example, styrene, alpha-methyl-styrene, para-methylstyrene and mixtures thereof. Styrene is preferably used. Suitable dicarboxylic acid anhydrides are, for example, maleic anhydride, chloromaleic anhydride, citraconic anhydride, cyclohexylmaleic anhydride, benzyl maleic anhydride, phenyl maleic anhydride, aconitic anhydride, propyl maleic anhydride and mixtures thereof. Maleic anhydride (MA) is preferably used. Polymer B preferably consists of styrene and maleic anhydride and can contain 5-40 mol% of maleic anhydride. In particular, polymer B contains 22-32 mol% of maleic anhydride.

Polymer B can also contain imide monomer units or spirodilactone units. Imide monomer units which can be present in polymer B are N-phenylmaleimide, maleimide, citraconimide, itaconimide, aconimide, N-methylmaleimide or mixtures thereof. The spirodilactone units can form by heating the polymer B. The dicarboxylic anhydride content o polymer B must remain at least 5 mol%. Polymer B can be prepared by copolymerising the vinyl-aromatic monomer units and the dicarboxylic acid anhydride monomer units and/or the imide monomer units in a known manner. Imide units can also be obtained by reacting some of the dicarboxylic acid anhydride units in the polymer B with a primary amine or ammonia. Examples of amines which can be used are: aniline and methylamine. Polymer B is present in the polymer composition in an amount of 5-70 parts by weight, preferably 20-40 parts by weight. The amount of polymer B in the polymer composition can proportionally be lowered when a functionalised polymer B is used as compatibiliser. The polymer composition according to the invention can also contain an elastomer or an elastomer-containing composition as an impact modifier. Examples of suitable elastomers or elastomer-containing compositions are: polybutadiene, ethylene-propylene rubber (EPR) , ethylene-propylene-diene rubber (EPDM) , functionalised EPDM, acrylonitrile-butadiene-styrene copolymer (ABS), polybutyl acrylate and silicone elastomer. 0-50% by weight of the elastomer or of the elastomer-containing composition can be added to the polymer composition. Preferably, 0-30% by weight are added.

The polymer compositions can be prepared by mixing polyolefin A, polymer B and the compatibiliser using conventional mixing eguipment such as extruders and mixers. In this operation the mixing temperature must be higher than the glass transition temperature of the polymer B and also higher than the glass transition temperature or the melting point of the polyolefin A.

The polymer composition according to the invention can also contain the customary additives, such as fibres, fillers, plasticisers, flame retardants and stabilisers.

The invention is further illustrated with the aid of the examples, without being restricted thereto. The Izod is determined in accordance with ISO R180/4A (23°C; measured parallel to the direction of - 1 -

injection-moulding).

The modulus of elasticity is determined in accordance with ISO 178 (23°C; measured parallel to the direction of injection-moulding).

Delamination (—=very poor; -=poor; +=good; ++=ver good). The delamination was determined by judging the appearance of the injection moulded polymer compositions.

Example I

A mixture of polypropylene (PP), styrene-maleic anhydride copolymer (SMA) and compatibiliser was prepared i a Brabender kneader; conditions: 230°C, 5 min mixing at 80 rpm, and then injection-moulded.

The polypropylene which was used is Stamylan P 83EOO^R. The SMA which was used is Stapron 28110^R. (Both products from DSM N.V.)

10% by weight of a polypropylene modified with NH₂ groups was used as compatibiliser C. The polypropylene modified with NH₂ groups was synthesised as follows: 100 g of Hostaprime HC5^R (a maleic anhydride-modified polypropylene from Himont) was added in small portions in the course of 1 hour to a waterfree solution of 25 g of 1,3 diaminobenzene in 1 dm³ of xylene, which was stirred under N₂. The temperature of the 1,3-diaminobenzene/xylene solution was 140°C. After all of the 100 g of Hostaprime HC5^r had dissolved, the reaction mixture was stirred for a further 30 minutes under N₂ at 110°C. The reaction mixture was then poured out hot into a 10-fold volume excess of methanol. The precipitated PP-g-NH₂ was filtered off, washe with methanol and dried at 60°C under vacuum.

Comparative results were obtained when 10% by weight of a polypropylene modified with oxazoline-groups or isocyanate-groups was used as compatibilisesr C. TABLE 1

PP/SMA/C Modulus of elasticity Izod Delamination (parts by weight) (N/mm²) (kJ/m² )

60/30/10 1800 ++

Comparative Experiments A and B

The same polypropylene and SMA as in Example I wer used for the Comparative Experiments A and B.

The mixtures were obtained by using the same metho as in Example I. In comparative experiment B, the compatibiliser C used was 10% by weight of Kraton G 1652^R according to JP-A-63-205341. Results are given in Table 2.

TABLE 2

PP/SMA/C Modulus of elasticity Izod Delamination (parts by weight) (N/mm² ) (kJ/m²)

A. 70/30/0 1800 2

B. 60/30/10 1400 4

The mixture from Example I has a clearly higher impact strength than a mixture to which no compatibiliser has been added, as in comparative experiment A.

It can clearly be seen that when a compatibiliser according to the invention is used the rigidity is higher, with retention of the impact strength as in Example I. The polymer composition according to the invention also shows less delamination.

Claims

C L I S

1. A polymer composition comprising a crystalline or semi-crystalline polyolefin A, a polymer B based on vinyl-aromatic monomer units and dicarboxylic acid anhydride monomer units, and a compatibiliser, characterised in that the compatibiliser is a functionalised polyolefin A or a functionalised polymer B.

2. A polymer composition according to claim 1, characterised in that 0.1-40 parts by weight of the compatibiliser is present in the polymer composition based on the sum of polyolefin A, polymer B and the compatibiliser.

3. A polymer composition according to anyone of claims 1-2 characterised in that 0.1-20 parts by weight of the compatibiliser is present in the polymer composition based on the sum of polyolefin A, polymer B and the compatibiliser.

4. A polymer composition according to anyone of claims 1-3 characterized in that the compatibiliser is a functionalised polyolefin A containing one or more oxazoline, isocyanate or amine groups.

5. A polymer composition according to anyone of claims 1-3 characterized in that the compatibiliser is a reaction product of polymer B and a linear or branched alkyl compound which contains 10-200 carbon atoms and a terminal functional group.

6. A polymer composition according to claim 5, characterised in that 20-90% of the dicarboxylic acid anhydride groups in the functionalised polymer B have been converted.

7. A polymer composition according to anyone of claims 5- characterised in that the terminal functional group is primary amine.

8. Process for obtaining one or more polymer compositions according to anyone of claims 1-7, characterised in that polyolefin A, polymer B and the compatibiliser are mixed at a temperature which is higher than the glass transition temperature of polymer B and higher than the glass transition temperature or the melting point of polyolefin A.

9. Products entirely or partially formed from a polymer composition according to anyone of claims 1-7 or obtained using a process according to claim 8.

10. Polymer composition, process and products as essentially- described and/or illustrated in more detail in the examples.