EP0985002A2

EP0985002A2 - Toughened polyketone composition

Info

Publication number: EP0985002A2
Application number: EP98922978A
Authority: EP
Inventors: James Graham Bonner
Original assignee: BP Chemicals Ltd
Current assignee: BP Chemicals Ltd
Priority date: 1997-05-29
Filing date: 1998-05-27
Publication date: 2000-03-15
Also published as: WO1998054262A1; JP2002500692A; WO1998054261A3; WO1998054261A2; AU7543798A; AU7543698A

Abstract

A polymer composition comprising: (A) a major amount of a polyketone having a linear alternating structure of (a) units derived from carbon monoxide and (b) units derived from one or more olefinically unsaturated compounds; and (B) a minor amount of an amine functionalised elastomer wherein the amount of amine incorporated in the elastomer is from about 0.01 to 2.0 % by weight of the total weight of component (B). By carefully selecting the amount of amine which is incorporated in the elastomer the impact strength of the polyketone is improved.

Description

TOUGHENED POLYKETONE COMPOSITION

The present invention relates to polymer compositions containing a polyketone polymer which have improved toughness.

For the purposes of this patent, polyketones are defined as linear polymers having an alternating structure of (a) units derived from carbon monoxide and (b) units derived from one or more olefinically unsaturated compounds.

Although for the purposes of this patent polyketones correspond to this idealised structure, it is envisaged that materials corresponding to this structure in the main but containing small regimes (i.e. up to 10wt%) of the corresponding homopolymer or copolymer derived from the olefinically unsaturated compound, also fall within the definition.

Such polyketones have the formula:

[(CR₂-CR₂)C]_m (I) where the R groups are independently hydrogen or hydrocarbyl groups, and m is a large integer; they are disclosed in several patents e.g. US 3694412. Processes for preparing the polyketones are disclosed in US 3694412 and also in EP 181014 and EP 121965.

Polyketones have use as thermoplastics for the production of e.g. containers or parts for the automotive industry. Such uses require the polymer to have suitable impact properties. Accordingly, it is known to incorporate into polyketones additives which improve the impact resistance properties of the polymer.

US 5,369,170 relates to a composite system comprising an aminated modified polyolefin and a linear alternating polymer of carbon monoxide and at least one ethylenically unsaturated hydrocarbon. The composite structure is produced by reacting a polyolefin with excess amine to form an imide with a free primary amine and causing the primary amine to react with a polyketone chain to form a pyrrole. These reactions can occur during a blending process. Compatibilisation is said to be achieved by the formation of polyketone/polyolefin graft copolymers at the interface of the polymers.

It has now been found that when an aminated elastomer is used to improve the impact strength of a polyketone polymer, the impact strength of the polymer composition is dependent upon the amount of amine which is incorporated in the elastomer. Accordingly, the present invention relates to a polymer composition which comprises: (A) a major amount of a polyketone having a linear alternating structure of (a) units derived from carbon monoxide and (b) units derived from one or more olefinically unsaturated compounds; and (B) a minor amount of an amine functionalised elastomer wherein the amount of amine incorporated in the elastomer is from about 0.01 to 2.0% by weight of the total weight of component (B). Preferably, the amount of amine incorporated in the elastomer is from 0.05 to 1.0% by weight of the total weight of component (B). The optimum amount of amine varies depending on the elastomer.

Preferably the amine functionalised elastomer is an amine functionalised polyolefinic or styrenic elastomer.

The polyolefinic elastomer which is functionalised with the amine can be a copolymer of an olefin e.g. propylene with ethylene, butene or other unsaturated aliphatic hydrocarbons or ethylene with propylene and a diene. Such copolymers are known and any such polymer can be used. It is preferred that the polyolefinic elastomer is an ethylene-propylene rubber or an ethylene/propylene/diene polymer (EPDM), most preferably EPDM. EPDM is an amorphous elastomeric polyolefin having a random distribution of units derived from ethylene, propylene and one or more dienes (e.g. dicyclopentadiene or hexa-l,4-diene) along the polymer backbone.

The styrenic elastomer which is functionalised with the amine can be a styrenic block copolymer. The term "styrenic block copolymer" is used to indicate a thermoplastic elastomer characterised by at least one block of units derived from one or more vinyl aromatic hydrocarbons (A block) and at least one block of units derived from one or more olefins other than a vinyl aromatic hydrocarbon (B block). The vinyl aromatic hydrocarbon useful as the precursor of A blocks has a vinyl group attached directly to an aromatic ring. Preferred vinyl aromatic compounds are styrene and substituted styrenes. Illustrative substituted styrenes include α-methyl styrene, α-ethylstyrene, p-methylstyrene, m-methylstyrene, p- ethylstyrene, m-isopropylstyrene, divinyl benzene, α,4-dimethylstyrene, chlorostyrene and vinyl benzene chloride. Olefins useful as precursors of the B blocks include ethylene, propylene, butylene, and dienes (e.g. isoprene, butadiene, 2,3-dimethylbutadiene, 1,3-octadiene, 1,3-pentadiene and norbornene). Preferably the styrenic block copolymer has the structure A-B-A. The block copolymer may be partially hydrogenated. Hydrogenation of block copolymers is well known in the art. Examples of styrenic block copolymers include styrene-ethylene/butylene- styrene block terpolymer (SEBS), styrene-butadiene-styrene block terpolymer (SBS) and styrene-isoprene-styrene block terpolymer (SIS). SEBS styrenic block copolymers are sold by Shell under the trade name of Kraton and by Asahi under the trade name of Tuftec.

Component (B) of the polymer composition of the present invention may comprise a mixture of two or more amine functionalised elastomers.

The amine functionalised elastomer may be obtained by (a) graft copolymerising an elastomer, preferably a polyolefinic or styrenic elastomer, with at least one polymerisable ethylenically unsaturated carboxylic acid or derivative thereof and (b) reacting the resulting graft copolymer with a compound (C) which has at least two primary or secondary amino groups at least one of which is a primary amino group. Polymerisable ethylenically unsaturated carboxylic acids and derivatives thereof which are graft copolymerised with the elastomer include, for example, acrylic acid, methacrylic acid, maleic acid, itaconic acid, citraconic acid, mesaconic acid, maleic anhydride, 4-methyl cyclohex-4-ene-l,2-dicarboxylic acid anhydride, bicyclo (2.2.2) oct-5-ene-2,3-dicarboxylic acid anhydride, 1,2,3,4,5,8,9,10- octahydronaphthalene-2,3 dicarboxylic acid anhydride, 2-oxa-l,3-diketospiro (4.4) non-7-ene, bicyclo (2.2.1) hept-5-ene-2,3-dicarboxylic acid anhydride, maleopimaric acid, tetrahydrophthalic anhydride, x-methyl-bicyclo (2.2.1) hept-5- ene -2,3-dicarboxylic acid anhydride, x-methyl-norborn-5-ene-2, dicarboxylic acid anhydride, norborn-5-ene-2,3-dicarboxylic acid anhydride. Preferably, maleic anhydride is used. When maleic anhydride is used as the polymerisable ethylenically unsaturated carboxylic acid anhydride, the amount which is graft copolymerised with a polyolefinic elastomer is typically from 0.001 to 30%, preferably from 0.1 to 10% more preferably from 0.15 to 5 % by weight of the graft copolymer. The amount of maleic anhydride which is graft copolymerised with a styrenic elastomer is typically from 0.001 to 5%, preferably from 0.05 to 3% more preferably from 0.5 to 2 % by weight of the graft copolymer.

Methods for preparing graft copolymers are well known and any suitable method can be used to prepare the graft copolymer of the elastomer and the polymerisable ethylenically unsaturated carboxylic acid or derivative thereof. One such suitable method comprises blending together the elastomer and the polymerisable ethylenically unsaturated carboxylic acid or derivative thereof in the presence of a free radical initiator, such as an organic peroxide or hydroperoxide, at a temperature which is above the melting point of the elastomer and which provides a suitable half-life of the free radical initiator. Suitable free radical initiators are well known. This grafting process can be carried out using known mixing equipment such as, for example, a Brabender mixer, a Banbury mixer or a roll mill. Preferably, the grafting process is carried out in a closed vessel. A convenient method of preparing the graft copolymer is therefore to extrude the elastomer, the polymerisable ethylenically unsaturated carboxylic acid or derivative thereof and an organic peroxide or hydroperoxide through a single or multiple screw extruder. Alternatively, the elastomer may be dissolved or suspended in a solvent and the resulting solution or suspension is mixed with the polymerisable ethylenically unsaturated carboxylic acid or derivative thereof and the free radical initiator. The compound (C) having at least two primary or secondary amino groups at least one of which is a primary group which is reacted with the graft copolymer is preferably a diamine having two primary amino groups and up to 16 carbon atoms inclusive and at least two carbon atoms between the primary amino groups. The diamines suitably contain aromatic moieties linking the amino groups as illustrated by phenylenediamine, 4,4'-diaminobiphenyl and di(4-aminophenyl) ether, or the diamines contain cycloaliphatic linking moieties such as in the case of di(4-aminocyclohexyl)methane or 1,4-diaminocyclooctane. The preferred diamines, however, are the acyclic terminal primary diamines of the formula: NH₂(CH₂)_n H₂ (I) wherein n is an integer from 2 to 16 inclusive. Such polymethylenediamines include trimethylenediamine, tetramethylenediamine, hexamethylenediamine, decamethylenediamine, dodecamethylenediamine and hexadecamethylenediamine.

Of these diamines dodecamethylenediamine is preferred. The compound (C) which is reacted with the graft copolymer can also suitably be a polyalkylene polyamine, or a mixture thereof, having the formula:- H₂N(R-NH)_nH (II) wherein R is a divalent aliphatic hydrocarbon group having 2 to 4 carbon atoms and n is an integer in the range from 1 to 10. More preferably the amine is a polyalkylene polyamine of the formula (II) wherein R is the group -CH₂CH₂- and n has a value of 2 to 6, i.e. a polyethylene polyamine. Examples of suitable polyethylene polyamines include triethylene tetramine and tetraethylene pentamine. Hydroxyalkyl amines, for example ethanolamine, diethanolamine, 2- hydroxypropylamine and N-hydroxy-ethyl ethylenediamines, and the like may also be used as the compound (C).

Furthermore, compound (C) can be a compound of formula (III), H₂N(CHR¹CHR²O)„CHR³CHR⁴NH₂ (III) wherein one of R¹ and R² is hydrogen and the other is hydrogen or lower alkyl, preferably C₂-C6 alkyl, more preferably methyl, and n is an integer from 1 to 40, preferably 1 to 10, more preferably 1 to 7, for example 2 to 7, one of R³ and R⁴ is hydrogen and the other is hydrogen or lower alkyl, preferably C₂-C₆ alkyl, more preferably methyl.

In particular where the compound (C) is of formula (III) it is preferred that compounds of formula, NH₂CH(CH₃)CH₂[OCH₂CH(CH₃)]_xNH₂ where x = 33.1, 5.6 and 2.6 are used. These compounds are commercially available and are marketed under the trade names Jeffamine D2,000, D400 and

D230 respectively.

The amount of compound (C) which is reacted with the graft copolymer is from 0.01 to 2.0%, preferably from 0.05 to 1.0% by weight of the amine functionalised graft copolymer. The optimum amount of compound (C) varies depending on the graft copolymer.

Compound (C) can be reacted with the graft copolymer having an elastomeric backbone which has been grafted with at least one polymerisable ethylenically unsaturated carboxylic acid or derivative thereof, in several ways; a preferred method is to react them in the melt by melt mixing them in known mixing equipment e.g. a Brabender mixer, a Banbury mixer or a roll mill or twin screw extruder.

Alternatively, an amine functionalised polyolefinic elastomer may be obtained via a "masked" polymerisation as described in "High Performance

Polymers", S Datta (Ed. A Fawcett) Royal Society of Chemistry, London, 1990, Ch 2; "Polym. Prepr"., Am. Chem. Soc, Div. Polym. Chem. 1992, 33, 899; "Polym. Prepr"., Am. Chem. Soc, Div. Polym. Chem. 1990, 31, 456 and US 5,030,370. Thus, an amine functionality may be introduced using a direct polymerisation of ethylene and propylene or ethylene, propylene and a diene with an amine functionalised monomer. The amine functionality needs to be deactivated (masked) prior to introduction into the polymerisation medium and is regenerated during a demasking operation which is an integral part of the polymerisation process. The amine functionality is believed to be randomly distributed along the polyolefinic elastomer chain. The amine functionality is pendant from the backbone of the polyolefinic elastomer. This architecture requires the amine functionality to be polymerised into the polyolefinic elastomeric chain through an olefin to which the "masked" amine functionality is chemically linked. Examples of amine functionalised polyolefinic elastomers which may be obtained via this "masked" copolymerisation include EPDM-amine and ethylene-propylene-amine. As noted above for the purposes of this patent, polyketones are defined as linear polymers having an alternating structure of (a) units derived from carbon monoxide and (b) units derived from one or more olefinically unsaturated compounds. Suitable olefinic units are those derived from C₂ to C₂₀ alpha-olefins or substituted derivatives thereof or arylaliphatic olefinically unsaturated compounds such as styrene or alkyl substituted derivatives of styrene. It is preferred that such olefin or olefins are selected from C₂ to Cβ normal alpha-olefins (i.e. straight chain alpha-olefins) and it is particularly preferred that the olefin units are either derived from ethylene or most preferred of all from a mixture of ethylene and one or more C₃ to C_O normal alpha-olefin(s) especially propylene or butene. In these most preferable materials it is further preferred that the molar ratio of ethylene units to C₃ to C_ normal alpha-olefin units is greater than or equal to 1 most preferably between 2 and 30.

The polyketones employed in the invention preferably have a number average molecular weight of from 1000 to 500,000, preferably from 15,000 to 300,000, more preferably from 40,000 to 200,000 as determined by gel permeation chromatography.

The melting point of the polyketones is preferably between 175 and 300°C, preferably from 180 to 225°C. The amine functionalised elastomer is incorporated in the polyketone in an amount of between 0.5 and 50% by weight, preferably from 5 to 40% and more preferably from 10 to 30% by weight, based on the weight of the polyketone plus amine functionalised elastomer.

Particularly preferred amine functionalised elastomers include a SEBS block terpolymer grafted with maleic anhydride and subsequently reacted with an amine (compound (C)).

The compositions of the present invention may also contain conventional additives such as antioxidants, stabilisers, processing aids, fillers etc.

The present invention provides a polyketone polymer composition having significant impact strength improvement.

The scope of the present invention extends to moulded or extruded articles including containers (for example, bottles, trays, cups), automotive parts, sheets and profile sections comprising the polymer composition as defined hereinbefore. A further aspect of the invention relates to the use of an amine functionalised elastomer to increase the impact strength of a polyketone polymer. The following Examples illustrate the invention.

Determination of Melt Flow Rate

The Melt Flow Rate (MFR) of the polyketone was measured using a Davenport Melt Index Tester. Tests were carried out at a temperature of 240°C or 250°C and an applied load of 1.2 kg or 5 kg. The MFR was calculated from the mass of extrudate pushed through a die (2.095 mm diameter) over a 30 second period on application of the load 4 minutes after charging the polymer into the barrel of the instrument at a temperature of 240°C or 250°C. Otherwise standard MFR procedures were followed (e.g. ISO 1133).

EXAMPLE 1

Polyketone/amine functionalised elastomer compositions were prepared using a PRISM TSE16 co-rotating twin screw extruder. The extruder was operated at a screw speed of 200rpm and with the following set of temperatures: zone 1 (feed) 195-200°C; zone 2, 205-215°C; zone 3 (die) 215-230°C. The appropriate amount of amine functionalised elastomer was either preblended with the polyketone prior to being fed into the extruder or fed independently via an additional feeder. Appropriate levels of stabilisers and antioxidants were premixed with the polyketone. Extruder outputs were maintained at a level to give constant 60% torque on the screws.

The elastomer used was a maleic anhydride modified styrene-^' ethylene/butene-styrene (SEBS) block terpolymer (Kraton FG1901X) supplied by

Shell Chemicals, or the same material reacted with an amine.

The reaction with the amine was carried out by processing the maleic anhydride modified SEBS block terpolymer in the presence of a quantity of 1,12- diaminododecane using a PRISM TSE16 co-rotating twin screw extruder. The extruder operated at a screw speed of 150rpm and with the following set of temperatures: zone 1 (feed) 180°C: zone 2, 200°C: zone 3 (die) 210°C. The maleic anhydride modified SEBS block terpolymer and diamine were premixed and fed to the extruder at a rate which ensured a 35% torque on the screws during production.

The polyketone used was a terpolymer of ethylene, propylene and carbon monoxide having a melting point of 212°C and a melt flow rate (MFR) of

16g/10mins at 240°C and a 5kg load. After compounding, the polyketone/amine functionalised elastomer composition was compression moulded into plaques, 150 x 150 x 4mm, using the following conditions:

Temp: 20°C above polyketone melting point

Preheat time: 5 mins Pressing time: 5 mins under 15 tonnes

Cooling: Crash cooled with water.

Samples for Izod impact testing were machined from the plaques and tested according to ASTM D256. Notched samples were tested, with a notch radius of

0.25mm. A pendulum weight and position was employed, such that it had a potential energy of 1545mJ.

Results of the impact testing are shown below. The most effective composition was tested at -40°C as well as 23°C.

EXAMPLE 2

Example 1 was repeated except that the graft copolymer used was a maleic anhydride modified styrene-ethylene/butene-styrene (SEBS) block terpolymer supplied by Asahi Chemical (Tuftec M1962). The polyketone used had a melting point of 189°C and a melt flow rate (MFR) of 44g/10minutes at 240°C/ 5kg.

The results of Izod impact testing are shown below. The most effective composition was tested at -40°C as well as 23 °C.

EXAMPLE 3

Polyketone/amine functionalised elastomer compositions were prepared using a PRISM TSE16 co-rotating twin screw extruder. The extruder was operated at a screw speed of 175rpm and with the following set of temperatures: zone l(feed) 190-195°C; zone 2, 215-225°C; zone 3(die) 225-230°C. The appropriate amount of the amine functionalised elastomer was either preblended with the polyketone prior to being fed into the extruder or fed independently via an additional feeder. Appropriate levels of stabilisers and antioxidants were premixed with the polyketone. Extruder outputs were maintained at a level to give constant 50% torque on the screws.

The polyketone used was a terpolymer of ethylene, propylene and carbon monoxide, and had a melting point of 218°C and a melt flow rate(MFR) of 106g/10mins with a 1.2 kg load at 250°C. The amine functionalised elastomer was an amine functionalised ethylene-propylene rubber (Paratone 8950) supplied by Exxon Chemicals (Paramins).

After compounding, the polyketone/amine functionalised elastomer was injection moulded into tensile bars using a Battenfeld BA230 injection moulder machine. Samples for Izod impact testing were machined from these and tested as in Example 1.

The results of Izod impact testing are shown below:

Claims

Claims:

1. The present invention relates to a polymer composition which comprises: (A) a major amount of a polyketone having a linear alternating structure of (a) units derived from carbon monoxide and (b) units derived from one or more olefinically unsaturated compounds; and (B) a minor amount of an amine functionalised elastomer wherein the amount of amine incorporated in the elastomer is from about 0.01 to 2.0% by weight of the total weight of component (B).

2. A polymer composition as claimed in claim 1 wherein the amount of amine incorporated in the elastomer is from 0.05 to 1.0% by weight of the total weight of component (B).

3. A polymer composition as claimed in claims 1 or 2 wherein the amine functionalised elastomer is an amine functionalised polyolefinic or styrenic elastomer.

4. A polymer composition as claimed in claim 3 wherein the elastomer which is functionalised with the amine is an ethylene-propylene rubber or an ethylene/propylene/diene polymer (EPDM).

5. A polymer composition as claimed in claim 3 wherein the elastomer which is functionalised with the amine is a thermoplastic styrenic block copolymer having at least one block of units derived from one or more vinyl aromatic hydrocarbons (A block) and at least one block of units derived from one or more olefins other than a vinyl aromatic hydrocarbon (B block).

6. A polymer composition as claimed in claim 5 wherein the A block is derived from a vinyl aromatic hydrocarbon selected from the group consisting of styrene, ╬▒-methyl styrene, ╬▒-ethylstyrene, p-methylstyrene, m-methylstyrene, p- ethylstyrene, m-isopropylstyrene, divinyl benzene, ╬▒,4-dimethylstyrene, chlorostyrene and vinyl benzene chloride.

7. A polymer composition as claimed in claim 5 or claim 6 wherein the B block is derived from an olefin selected from the group consisting of ethylene, propylene, butylene, and dienes.

8. A polymer composition as claimed in any one of claims 5 to 7 wherein the styrenic block copolymer is selected from the group consisting of styrene- ethylene/butylene-styrene block terpolymer (SEBS), styrene-butadiene-styrene block terpolymer (SBS) and styrene-isoprene-styrene block terpolymer (SIS).

9. A polymer composition as claimed in any one of the preceding claims wherein the amine functionalised elastomer is a graft copolymer of an elastomer grafted with at least one polymerisable ethylenically unsaturated carboxylic acid or derivative thereof; and which has been reacted with a compound (C) having at least two primary or secondary amino groups at least one of which is a primary amino group.

10. A polymer composition as claimed in claim 9 wherein the polymerisable ethylenically unsaturated carboxylic acid derivative is maleic anhydride.

11. A polymer composition as claimed in claim 10 wherein the elastomer is a polyolefinic elastomer and the amount of maleic anhydride which is graft copolymerised with the polyolefinic elastomer is from 0.001 to 30% by weight of the graft copolymer.

12. A polymer composition as claimed in claim 10 wherein the elastomer is a styrenic elastomer and the amount of maleic anhydride which is graft copolymerised with the styrenic elastomer is from 0.001 to 5% by weight of the graft copolymer.

13. A polymer composition as claimed in any one of claims 9 to 12 wherein compound (C) is a compound of the formula:

NH₂(CH₂)_nNH₂ (I) wherein n is an integer from 2 to 16 inclusive.

14. A polymer composition as claimed in any one of claims 9 to 12 wherein compound (C) is a compound of formula:

NH₂CH(CH₃)CH₂[OCH₂CH(CH₃)]_xNH₂ where x is in the range 1 to 40.

15. A polymer composition as claimed in claim 3 wherein the amine functionalised polyolefinic elastomer is a copolymer of ethylene, propylene and an amine functionalised monomer or a copolymer of ethylene, propylene, a diene and an amine functionalised monomer.

16. A polymer composition as claimed in any one of the preceding claims in which the amine functionalised elastomer is incorporated in the polyketone in an amount of between 0.5 and 50% by weight based on the weight of the polyketone and amine functionalised elastomer.

17. A moulded or extruded article comprising a polymer composition as claimed in any one of the preceding claims.

18. Use of an amine functionalised elastomer as defined in any one of the preceding claims to increase the impact strength of a polyketone polymer.

19. A process for preparing an amine functionalised elastomer as defined in any one of claims 9 to 14 and 16 which process comprises: (a) graft copolymerising an elastomer with at least one polymerisable ethylenically unsaturated carboxylic acid or derivative thereof; and (b) reacting the resulting graft copolymer with a compound (C) which has at least two primary or secondary amino groups at least one of which is a primary amino group.

20. A process for preparing an amine functionalised polyolefinic elastomer as defined in claims 15 or 16 which process comprises:

(a) masking an amine functional group which is chemically linked to an olefinic monomer; (b) copolymerising the masked amine functionalised monomer with ethylene, propylene and optionally a diene; and

(c) demasking the amine functional group.