WO2000042089A1

WO2000042089A1 - Polyketones having improved barrier properties

Info

Publication number: WO2000042089A1
Application number: PCT/GB1999/004051
Authority: WO
Inventors: Jose Maria Lagaron Cabello; Anthony Keith Powell
Original assignee: Bp Chemicals Limited
Priority date: 1999-01-15
Filing date: 1999-12-03
Publication date: 2000-07-20

Abstract

A melt processed barrier material having an oxygen permeability of less than 1 X 10-13 cc.cm cm?-2 s-1 cmH-1¿ at 23°C, 75% relative humidity (RH), which is obtainable by: A) melt processing a polyketone polymer composition comprising a polyketone polymer having an alternating structure of (a) units derived from carbon monoxide, and (b) units derived from ethylene and optionally no more than 5.75 mole % of units derived from an alpha olefin selected from the group consisting of propene and butene at a temperature which is less than 15°C above the melting point of the polyketone polymer and maintaining the polyketone polymer composition at the melt processing temperature for less than 3 minutes, and B) crash cooling the polyketone polymer composition at a rate of above 20°C per minute.

Description

POLYKETONES HAVING IMPROVED BARRIER PROPERTIES

The present invention relates to barrier materials having very low oxygen permeabilities which are obtainable by melt processing a polyketone polymer composition under controlled conditions.

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 olefinicaUy unsaturated compounds.

Such polyketones have the formula:

O

II

[(CR₁R₂-CR₃R₄)C]_m where the Rj_., R₂, R₃ and Rt 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 181014A and EP 121965N 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 10 wt%) of the corresponding homopolymer or copolymer derived from the olefinicaUy unsaturated compound, also fall within the definition.

EP 213671 A teaches that polyketones comprising units derived from carbon monoxide, ethylene and an alpha olefin (e.g. propene or butene) have lower melting points than corresponding copolymers comprised only of units derived from carbon monoxide and ethylene. A quantitative relationship is shown to exist between the proportion of units derived from propene in the polyketone and the melting point. The most preferred range of melting points is said to be from 195 to 235°C, corresponding to a specific range of ethylene: propene ratios. Within this preferred range, examples are given of terpolymers comprising units derived from carbon monoxide, ethylene and propene having melting points of 214°C and 220°C respectively (estimated to correspond to contents of units derived from propene of about 4.5 and 4.0 mol% respectively with respect to the total polymer composition). There is no discussion of the oxygen barrier properties of these polyketones.

Although polyketones are known to exhibit good barrier properties, in particular against oxygen, it is desirable to improve these properties. It is known to do this by altering the manufacturing process of the polyketone. US 4895689 discloses polyketone terpolymers including as the third component units derived from propene, of which the barrier properties are improved by cooling a heated solution cast film of the polyketone at a selected rate. Ethylene/propene/CO terpolymers having melting points of from 214°C to 224°C (estimated to correspond to contents of units derived from propene of between about 4.5 and 3.5 mol% respectively) are disclosed, having oxygen permeabilities at 30°C and 0% relative humidity (RH) increasing from 1.5 x 10^"12 cc.cm cm^"2 s^"1 crnHg^"1 for 224°C melting point (3.5 mol% propene) to 5.3 x 10^"12 cc.cm cm^"2 s^"1 crnHg^'1 for 214°C melting point (4.5 mol% propene).

US 5,077,385 describes a melt processed polymer material having improved oxygen, water and/or carbon dioxide barrier properties comprising a polymer comprising at least one ethylenically unsaturated hydrocarbon which has been heat treated to a temperature in the range of 2-40°C above the melting point of the linear alternating polymer then cooled at a rate of about 1 to 20° per minute. It is stated that there appears to be good results using compression moulding temperature 5-15°C above the resin melting point. 15°C above the resin melting point is said to be best. Polyketone polymers usable in US 5,077,385 have preferred melting points of between about 210-260°C (an estimated maximum content of units derived from propene of 4.5 mol%). Specifically disclosed are ethylene/propene/CO terpolymers having a content of units derived from propene of 0, 4.7, 5.0, 8.5, 8.9 and 10.5 %. An alternative to altering the manufacturing process is to blend the polyketone with a further polymer. EP 759458A discloses blends of polyketones and PVC; in this disclosure, a carbon monoxide/ethylene/propene terpolymer having a melting point of 206°C is shown to have an oxygen permeability at 23 °C and 75% relative humidity (RH) of 0.053 cc.mm/m²/day/atm, or 0.81 x 10^"13 cc.cm cm^"2 s^"1 crnHg^"1. However the addition of 10% uPVC to the polyketone reduces the permeability to 0.010 cc.mm/m²/day/atm. No other data for unblended polyketones is given. The content of units derived from propene of this terpolymer has subsequently been measured as 6.6mol%.

Surprisingly, it has now been found that for certain polyketone polymer compositions, very low oxygen permeabilities can be achieved by melt processing the polyketone polymer composition under carefully controlled conditions followed by crash cooling. Accordingly, the present invention provides a melt processed barrier material having an oxygen permeability of less than 1 x 10^"13 cc.cm cm^"2 s^"1 crnHg^"1 at 23°C, 75% relative humidity (RH), which is obtainable by:

(A) melt processing a polyketone polymer composition comprising a polyketone polymer having an alternating structure of (a) units derived from carbon monoxide, and (b) units derived from ethylene and optionally no more than 5.75 mole % of units derived from an alpha olefin selected from the group consisting of propene and butene at a temperature which is less than 15°C above the melting point of the polyketone polymer and maintaining the polyketone polymer composition at the melt processing temperature for less than 3 minutes; and (B) crash cooling the polyketone polymer composition at a rate of above 20°C per minute. The present invention is based on the unexpected finding that the optimum oxygen permeability for the barrier material is attained by carefully controlling the melt processing conditions and, contrary to the teachings of US 5,077,385, crash cooling the polyketone polymer composition at a rate of above 20°C. Without wishing to be bound by any theory, it is believed that the oxygen permeability of the barrier material is dependent upon the extent to which thermal degradation of the polyketone polymer occurs during melt processing. This problem of thermal degradation is of particular concern for carbon monoxide/ethylene/propene terpolymers and carbon monoxide/ethylene/butene terpolymers having low amounts of units derived from propene and butene respectively. A further unexpected advantage of the barrier material of the present invention relates to its relative permeability to oxygen and carbon dioxide. The permeability of polyketones to carbon dioxide is known to be higher than that to oxygen, which is an advantage in certain packaging applications where CO₂ is used to flush out oxygen; permeability to CO₂ allows excess CO₂ to escape from the package after flushing, whilst oxygen is still excluded. Accepted CO₂ to O₂ permeability ratios for polyketones in the prior art are between about 3 : 1 and 10: 1. However we have found that the ratio of CO₂ to O permeability for the polyketone barrier material of the present invention is substantially greater than this i.e. the permeability ratio is greater than 10: 1, preferably greater than 50: 1, more preferably greater than 100: 1.

Preferably, the polyketone polymer composition is melt processed at a temperature which is less than 10°C, more preferably less than 5°C, most preferably less than 2°C, for example, less than 1°C above the endset of melting of the polyketone polymer. The endset of melting is defined herein as the temperature corresponding to the end of the melting process in the polyketone polymer.

Preferably, for extrusion processing the polyketone polymer composition is maintained at the melt processing temperature (dwell time) for at least 30 seconds. Preferably, for compression moulding, the dwell time is at least 1 minute.

Preferably, the oxygen permeability of the barrier material at 23 °C, 75%RH is less than 0.8 x 10^" cc.cm cm^" s^" crnHg^" , more preferably less than 0.5 x 10^" cc.cm cm^" s^" crnHg^"1. Although figures quoted here are for 23°C and 75% RH, the low permeability is observed over the full range of humidities and thus the invention is not limited in this respect.

The amount of optional units derived from propene and/or butene in the polyketone polymer is preferably no more than 5.5, more preferably no more than 5 mol%, most preferably no more than 4 mol%, particularly no more than 3 mole%, for example, no more than 2.5 mol%. Preferably, the polyketone polymer composition is crash cooled after melt processing at a rate of at least 30°C per minute, more preferably at a rate of at least 40°C per minute.

The polyketone polymer may include units derived from an optional further alpha olefin (in addition to units derived from propene and/or butene). The optional further alpha olefin may be selected from the group consisting of pentene, hexene, heptene and octene.

The polyketone polymer may contain units derived from more than one further alpha olefin. The Melt Flow Rate (5kg load at 240°C, 2.095 diameter die) of the polyketone polymer is typically in the range 5-200, preferably 10-150, more preferably 20-100 for example 40-80g/10 mins.

The polyketone polymer will suitably have a weight average molecular weight of between 20,000 and 1,000,000 preferably between 30,000 and 250,000 for example 40,000 to 180,000.

It is envisaged that the barrier material may comprise a polyketone polymer composition comprising a blend of the polyketone polymers defined above. Also, the barrier material may comprise a polyketone polymer composition comprising a polyketone polymer as defined above blended with other polyketone polymers, for example, ethylene/pentene/CO, ethylene/hexene/CO, ethylene/heptene/CO or ethylene/octene/CO terpolymers.

The barrier material may also comprise a polyketone polymer composition comprising a blend of a polyketone polymer as defined above with another polymer (for example, polyethylene, polypropylene, PVC, polystyrene and polyesters); the nature and amount of such a polymer will depend upon what modifications of the polymer properties are required. Furthermore, the barrier materials of the present invention may contain conventional polymer additives such as anti-oxidants, stabilisers, fillers, mould release agents and processing aids (such as internal and external lubricants).

The polyketone polymers can be prepared using conventional batch or continuous reactor techniques.

Although in the Examples below, the samples of the barrier materials of the present invention are prepared by compression moulding, articles can also be made by extrusion processes to produce coatings, films, sheets, pipes, tubes, containers, liners (including liners for pipes, containers, and tanks, such liners being formed from mono-layers of the polyketone composition of the present invention, and are fitted internally to the pipe, container, tank etc.) and closures. Extrusion techniques can result in lower permeabilities than compression moulding, as is well known, due to molecular orientation.

The scope of the present invention extends to films and articles, (for example moulded articles) comprising the barrier materials as defined hereinbefore, which can be used in packaging applications requiring good oxygen barrier properties and also in applications requiring good hydrocarbon and chemical resistance.

Suitable goods which may be packaged using the barrier materials of the present invention include foodstuffs, beverages, household goods, healthcare products, medical products and pharmaceuticals.

In a further aspect of the present invention there is provided goods (for example, foodstuffs, beverages, household goods, healthcare products, medical products and pharmaceuticals) contained in a packaging material comprising the barrier material as defined hereinbefore.

In yet another aspect of the present invention there is provided the use of a packaging material comprising the barrier material as defined hereinbefore to package goods (for example, foodstuffs, beverages, household goods, healthcare products, medical products and pharmaceuticals), particularly those in liquid, wet or dry form.

The packaging material may be a film (for example, a pouch, a seal for a tray, bowl or other receptacle) or a moulded article (for example, a tray, cup, bowl, or other receptacle).

The barrier material of the present invention is particularly useful for pipe applications where it is important to exclude oxygen from the material being conveyed by the pipe or to limit oxygen ingress into the material being conveyed by the pipe.

In yet another aspect of the present invention there is provided a pipe comprising the barrier material as defined hereinbefore for use in conveying, for example, hydrocarbons or industrial chemicals. Typical hydrocarbons include fuels, crude oils, and solvents such as toluene and heptane) while typical industrial chemicals include ethanol and acetone.

The packaging material or pipe may be formed from a monolayer of the barrier material as defined hereinbefore. Alternatively, the packaging material or pipe may be formed from a multi-layered structure comprising at least one layer which is a barrier material as defined hereinbefore. A multi-layered structure is preferred. Such multi- layered structures may be prepared by co-extrusion e.g. multi-layered film or pipe produced by co-extrusion or by lamination. Typically, the multi-layered structure comprises 2 to 12 layers, preferably 3 to 7 layers. Preferably, the multi-layered structure comprises 3 or 6 layers, having an internal layer which is a barrier material as defined hereinbefore. Where the packaging material or pipe is a multi-layered structure, the layer(s) of the barrier material, as hereinbefore defined, suitably has a thickness of at least 3 μm and up to 5000 μm, preferably in the range 5 to 1000 μm, more preferably for food packaging in the range 5 to 50 μm and for pipes (hydrocarbon resistance) in the range 25 to 500 μm. Tie-layers may be required to bond the different layers of the multi-layer structure (see for example, EP 670869).

In yet a further aspect of the present invention there is provided a liner comprising a monolayer of the barrier material as defined hereinbefore fitted internally to a pipe, container (receptacle) or a tank.

The present invention also provides in another aspect a process for making a barrier material having an oxygen permeability of less than 1 x 10^"13 cc.cm cm^"2 s^"1 crnHg^"1 at 23°C, 75% relative humidity (RH), which process comprises (A) melt processing a polyketone polymer composition comprising a polyketone polymer having an alternating structure of (a) units derived from carbon monoxide, and (b) units derived from ethylene and optionally no more than 5.75 mole % of units derived from an alpha olefin selected from the group consisting of propene and butene at a temperature which is less than 15°C above the melting point of the polyketone polymer and maintaining the polyketone polymer composition at the melt processing temperature for less than 3 minutes; and (B) crash cooling the polyketone polymer composition at a rate of above 20°C per minute.

The process of the present invention may be used to form a film or a moulded article. By carefully controlling (i) the temperature at which melt processing of the polyketone polymer composition is carried out, (ii) the period of time for which the polymer composition is held at the melt temperature (dwell time) and (iii) the rate at which the polymer composition is cooled, the oxygen transmission through the film or moulded article (for example, a container or pipe) is reduced.

The process of the present invention has the preferred features described above. The invention is illustrated by the following examples and Figure.

Melt Processing

For barrier performance evaluation, 11cm diameter and about 150 micron thick films of the polyketone polymers were compression moulded between two polished aluminium sheets using a KOMTEC 40 tonne press. The polyketone polymer was initially held at the melt processing temperature (see Tables 1 and 2) for the dwell time (also given in Tables 1 and 2) at a dial pressure of 0.2MPa, following which the dial pressure was increased to 18MPa and simultaneously the films were cooled (at the cooling rates given in Tables 1 and 2) until the film reached a temperature of about 30°C. The dial pressure was maintained at a constant 18MPa during the cooling cycle.

Characterisation

The melting point of the ex-reactor powder was determined by differential scanning calorimetry (DSC). This was carried out using a DuPont DSC Model No. 990315. A heating rate of 10°C/min from -50°C up to 240°C was used under a nitrogen purge, followed by cooling at a rate of 10°C/min back down to -50°C. A second heating cycle at the same rate was then applied: the melting point (T_m) was evaluated from the second heating endotherm. The results are shown in the Examples. The content of units derived from propene or butene was determined by proton 1H

NMR using a JEOL GSX 270 spectrometer. The polymer was analysed as a solution in HFiP/CD₂Cl₂. The content of units derived from propene or butene is expressed in mole % of the total polymer composition.

The oxygen and carbon dioxide permeabilities were measured using the MOCON Oxtran (1000) ASTM D3985 and the MOCON Permatran (CIV) respectively. According to ASTM D3985 a film of polymer is mounted as a sealed semi-barrier between two chambers at ambient atmospheric pressure. One chamber is slowly purged by a stream of nitrogen and the other chamber contains oxygen. As oxygen gas permeates through the film into the nitrogen carrier gas, it is transported to a coulometric detector where it produces an electric current, the magnitude of which is proportional to the amount of oxygen flowing into the detector per unit time. Preparation of Polyketones Example 1

A carbon monoxide/ethylene copolymer was prepared under the following conditions:

100 ml methanol was charged to a mechanically stirred autoclave having a volume of 300 ml. The contents of the autoclave were brought to a temperature of 70°C. A 1 : 1 carbon monoxide/ethylene gas mixture was introduced into the autoclave until a pressure of 80 barg was reached. A catalyst solution was then introduced into the autoclave, consisting of:

6 ml methanol,

0.012 mmol palladium acetate, 0.01 1 mmol l,3-bis(diphenylphosphino)propane, and 0.4 mmol trifluoro acetic acid.

The autoclave pressure was maintained at 80 barg by introducing under pressure a 1 : 1 carbon monoxide/ethylene gas mixture. After 3 hours the polymerisation was stopped by depressurising the autoclave. The polymer was collected by filtration, washed with methanol and dried at a temperature of 70°C. 8g of copolymer was produced having a melting point determined by DSC of 252°C. Example 2

A carbon monoxide/ethene/propene copolymer was prepared under the following conditions:

11 litres of dichloromethane and 1.0 litre of propylene were charged to a mechanically stirred autoclave having a volume of 20 litres. The contents of the autoclave were brought to a temperature which was maintained in the range 68-70°C. A 1 : 1 carbon monoxide/ethene gas mixture was introduced until a pressure of 42 barg was reached. Tris(pentafluorophenyl)boron co-catalyst was then introduced into the autoclave. This was followed by addition of 0.2g (0.3 mmol) [Pd(dppp)(OAc)₂](BF₄)₂ catalyst (dppp = 1,3- bis(diphenylphosphino)propane; OAc = CH₃CO₂). The molar ratio of the boron co-catalyst to the palladium catalyst was 40:1.

The autoclave pressure was maintained in the range 42-45 barg by introducing on demand a 1 : 1 carbon monoxide/ethene gas mixture. The polymer was isolated by filtration, washed with isopropanol and then dried in vacuo. The polymer had a peak melting point determined by DSC of 248°C. The content of units derived from propene was determined by NMR as 1.0 mol %. Example 3 A carbon monoxide/ethylene/propene terpolymer was prepared in a 7.5 litre Parr autoclave using the following procedure: 3 litres methanol, 0.8 g [Pd(dppp)(PhCN)₂](BF₄)₂(dppp = 1,3- bis(diphenylphosphino)propane), 45 g of 5-C1-BSA (chloroborosalicylic acid) and 36.5 g of benzoquinone were placed into the base of the autoclave and then briefly manually stirred. The head of the autoclave was fitted to the base and fastened. The autoclave was purged three times by introducing a 1:1 mixture of ethyl ene/CO until a pressure of 10 barg was reached and then venting the autoclave. The last purge was used to pressure test the autoclave before final venting. Liquid propene (376 g) under 25 barg nitrogen was then measured into the autoclave, by volume, from calibration tanks. A 1 : 1 mixture of ethylene/CO was introduced to the autoclave until a pressure of 20 barg was reached and the contents of the autoclave were then heated to a temperature of 60°C. Once at temperature the autoclave pressure was increased to 50 barg with additional 1:1 ethylene/CO gas feed. The autoclave was maintained at a pressure of 50 barg by continuously feeding the 1 : 1 carbon monoxide/ethylene gas mixture. After 7.5 hours reaction time the autoclave was cooled before being depressurised. The autoclave was then purged with nitrogen before dismantling. The polymer slurry was removed and the polymer was collected by filtration. The autoclave was washed with acetone to remove any "loose" polymer and this was also collected by filtration. All of the removed polymer was washed with methanol, before being soxhlet extracted with methyl ethyl ketone (MEK) for 12 hours. After extraction, the polymer was collected by filtration and dried in vacuo at a temperature of 70°C for 12 hours. 1.2 kg of terpolymer was produced having a melting point determined by DSC of 242°C. The content of units derived from propene was determined by 13C NMR as 1.2 mol %. Example 4

A carbon monoxide/ethylene/propene terpolymer was prepared using the same procedure as in Example 3 except that 1.0 g [Pd(dppp)(PhCN)₂](BF₄)₂ (dppp = 1,3- bis(diphenylphosphino)propane) and 986 g of liquid propene were used. The reaction temperature was 53°C and the reaction time was 5.25 hours. 1.172 kg of terpolymer was produced having a melting point determined by DSC of 231°C. The content of units derived from propene was determined by 13C NMR as 2.2 mol %. Example 5 A carbon monoxide/ethylene/propene terpolymer was prepared using the same procedure as in Example 3 except that 0.721 g [Pd(dppp)(OAc)₂] (dppp = 1,3- bis(diphenylphosphino)propane; OAc = CH₃CO , 45.5 g of chloroborosalicylic acid, 36.8 g of benzoquinone, and 1.0 litres of liquid propene were used. The reaction temperature was 55°C, the reaction pressure was 45 barg and the reaction time was 6 hours. 904 g of terpolymer was produced having a melting point determined by DSC of 215°C. The content of units derived from propene was determined by 13C NMR as 5.4 mol %. Example 6 A carbon monoxide/ethylene/propene terpolymer was prepared under the following conditions:

80 ml dichloromethane and 10.2g propene were charged to a mechanically stirred autoclave having a volume of 300 ml. The contents of the autoclave were brought to a temperature of 73°C. A 1 : 1 carbon monoxide/ethylene gas mixture was introduced to the autoclave until a pressure of 50 barg was reached. A boron solution was then introduced to the autoclave, consisting of 0.3mmol of tris(pentafluorophenyl)boron in 20 ml of dichloromethane. This was followed by addition of a catalyst solution comprising: O.Olόmmol [Pd(dppp)(PhCN)₂](BF₄)₂ (dppp = l,3-bis(diphenylphosphino)propane) in 20 ml of dichloromethane.

The autoclave pressure was maintained at 50 barg by introducing under pressure a 1 : 1 carbon monoxide/ethylene gas mixture. Polymerisation was stopped after 1.5 hours by depressurising the autoclave. The polymer was collected by filtration, washed with methanol and dried at a temperature of 40°C. 20g of terpolymer was produced having a melting point determined by DSC of 225°C. The content of units derived from propene was determined by NMR as 2.9 mol %. Example 7

A carbon monoxide/ethylene/propene terpolymer was prepared under the following conditions: 80 ml dichloromethane and 20g propene were charged to a mechanically stirred autoclave having a volume of 300 ml. The contents of the autoclave were brought to a temperature of 73°C. A 1:1 carbon monoxide/ethylene gas mixture was introduced to the autoclave until a pressure of 50 barg was reached. A boron solution was then introduced into the autoclave, consisting of 0.3mmol of tris(pentafluorophenyl)boron in 20 ml of dichloromethane. This was followed by addition of a catalyst solution comprising:

O.Olόmmol [Pd(dppp)(PhCN)₂](BF₄) (dppp = l,3-bis(diphenylphosphino)propane) in 20 ml of dichloromethane.

The autoclave was maintained at a pressure of 50 barg by introducing under pressure a 1 : 1 carbon monoxide/ethylene gas mixture. Polymerisation was stopped after 1.25 hours by depressurising the autoclave. The polymer was collected by filtration, washed with methanol and dried at a temperature of 40°C. 18.2 g of terpolymer was produced having a melting point determined by DSC of 210°C. The content of units derived from propene was determined as 5.1 mol % by NMR. Example 8

A carbon monoxide/ethylene/propene terpolymer was prepared under the following conditions: 80 ml dichloromethane and 21g propene were charged to a mechanically stirred autoclave having a volume of 300 ml. The contents of the autoclave were brought to a temperature of 77°C. A 1:1 carbon monoxide/ethylene gas mixture was introduced to the autoclave until a pressure of 50 barg was reached. A boron solution was then introduced into the autoclave, consisting of 0.3mmol of tris(pentafluorophenyl)boron in 20 ml of dichloromethane. This was followed by addition of a catalyst solution comprising:

0.015mmol [Pd(dppp)(PhCN)₂](BF )₂ (dppp = l,3-bis(diphenylphosphino)propane) in 20ml of dichloromethane.

The autoclave pressure was maintained at 50 barg by introducing under pressure a 1:1 carbon monoxide/ethylene gas mixture. Polymerisation was stopped after 1.75 hours by depressurising the autoclave. The polymer was collected by filtration, washed with methanol and dried at 40°C. 16g of terpolymer was produced having a melting point determined by DSC of 201°C. The content of units derived from propene was determined by NMR as 5.8 mol %. Example 9 A carbon monoxide/ethylene/propene terpolymer was prepared under the following conditions:

80 ml dichloromethane and 26.9g propene were charged to a mechanically stirred autoclave having a volume of 300 ml. The contents of the autoclave were brought to a temperature of 73°C. A 1:1 carbon monoxide/ethylene gas mixture was introduced until a pressure of 50 barg was reached. A boron solution was then introduced into the autoclave, consisting of 0.3 mmol of tris(pentafluorophenyl)boron in 20 ml of dichloromethane. This was followed by addition of a catalyst solution comprising: O.Olόmmol [Pd(dppp)(PhCN)₂](BF ) (dppp = l,3-bis(diphenylphosphino)propane) in 20ml of dichloromethane. The autoclave pressure was maintained at 50 barg by introducing under pressure a

1 : 1 carbon monoxide/ethylene gas mixture. Polymerisation was stopped after 1.3 hours by depressurising the autoclave. The polymer was collected by filtration, washed with methanol and dried at a temperature of 40°C. 11.9g of terpolymer was produced having a melting point determined by DSC of 189°C. The content of units derived from propene was determined by 13C NMR as 7.2 mol %. Example 10 A carbon monoxide/ethylene/butene terpolymer was prepared under the following conditions:

80 ml dichloromethane and 20.2g butene were charged to a mechanically stirred autoclave having a volume of 300 ml. The contents of the autoclave were brought to a temperature of 70°C. A 1:1 carbon monoxide/ethylene gas mixture was introduced until a pressure of 50 barg was reached. A boron solution was then introduced into the autoclave, consisting of 0.15 mmol of tris(pentafluorophenyl)boron in 20 ml of dichloromethane. This was followed by addition of a catalyst solution comprising: O.Olόmmol [Pd(dppp)(PhCN)₂](BF₄)₂ (dppp = l,3-bis(diphenylphosphino)propane) in 20 ml of dichloromethane. The autoclave pressure was maintained at 50 barg by introducing under pressure a

1 : 1 carbon monoxide/ethylene gas mixture. Polymerisation was stopped after 1 hour by depressurising the autoclave. The polymer was collected by filtration, washed with methanol and dried at 40°C. 18.7g of terpolymer was produced having a melting point determined by DSC of 232°C. The content of units derived from butene was determined by NMR as 2.5 mol %. Example 11

A carbon monoxide/ethylene/butene terpolymer was prepared under the following conditions: 80 ml dichloromethane and 32.4 g butene were charged to a mechanically stirred autoclave having a volume of 300 ml. The contents of the autoclave were brought to a temperature of 70°C. A 1:1 carbon monoxide/ethylene gas mixture was introduced until a pressure of 50 barg was reached. A boron solution was then introduced into the autoclave, consisting of 0.15 mmol of tris(pentafluorophenyl)boron in 20 ml of dichloromethane. This was followed by addition of a catalyst solution comprising: O.Olόmmol [Pd(dppp)(PhCN)₂](BF )₂ (dppp = l,3-bis(diphenylphosphino)propane) in 20 ml of dichloromethane.

The autoclave pressure was maintained at 50 barg by introducing under pressure a 1 : 1 carbon monoxide/ethylene gas mixture. Polymerisation was stopped after 1 hour by depressurising the autoclave. The polymer was collected by filtration, washed with methanol and dried at 40°C. 18.2g of terpolymer was produced having a melting point determined by DSC of 217°C. The content of units derived from butene was determined by NMR as 4.2 mol %. Example 12

A carbon monoxide/ethylene/butene terpolymer was prepared under the following conditions:

80 ml dichloromethane and 41.2g butene were charged to a mechanically stirred autoclave having a volume of 300 ml. The contents of the autoclave were brought to a temperature of 70°C. A 1 : 1 carbon monoxide/ethylene gas mixture was introduced until a pressure of 50 barg was reached. A boron solution was then introduced into the autoclave, consisting of 0.15 mmol of tris(pentafluorophenyl)boron in 20 ml of dichloromethane. This was followed by addition of a catalyst solution comprising: O.Olόmmol [Pd(dppp)(PhCN)₂](BF )₂ (dppp = l,3-bis(diphenylphosphino)propane) in 20 ml of dichloromethane.

The autoclave pressure was maintained at 50 barg by introducing under pressure a 1 : 1 carbon monoxide/ethylene gas mixture. Polymerisation was stopped after 1.5 hours by depressurising the autoclave. The polymer was collected by filtration, washed with methanol and dried at 40°C. 22.6g of terpolymer was produced having a melting point determined by DSC of 207°C. The content of units derived from butene was determined by NMR as 4.8 mol %. Example 13

80 ml dichloromethane and 52g butene were charged to a mechanically stirred autoclave having a volume of 300 ml. The contents of the autoclave were brought to a temperature of 70°C. A 1 :1 carbon monoxide/ethylene gas mixture was introduced until a pressure of 50 barg was reached. A boron solution was then introduced into the autoclave, consisting of 0.15 mmol of tris(pentafluorophenyl)boron in 20 ml of dichloromethane. This was followed by addition of a catalyst solution comprising: O.Olόmmol [Pd(dppp)(PhCN)₂](BF₄) (dppp = l,3-bis(diphenylphosphino)propane) in 20 ml of dichloromethane.

The autoclave pressure was maintained at 50 barg by introducing under pressure a 1: 1 carbon monoxide/ethylene gas mixture. Polymerisation was stopped after 1.25 hours by depressurising the autoclave. The polymer was collected by filtration, washed with methanol and dried at 40°C. 14.5g of terpolymer was produced having a melting point determined by DSC of 198°C. The content of units derived from butene was determined by NMR as 6.2 mol %.

TABLE 1

σ>

TABLE 1 (continued)

ω c

CD in

H C H m w x m

H c ι m- to en

a. produced by Shell

TABLE 2

c O CO

H

C H 00 ω x m m H c m r en

Claims

Claims:

1. A melt processed barrier material having an oxygen permeability of less than 1 x 10^"13 cc.cm cm^"2 s^"1 crnHg^"1 at 23°C, 75% relative humidity (RH), which is obtainable by: (A) melt processing a polyketone polymer composition comprising a polyketone polymer having an alternating structure of (a) units derived from carbon monoxide, and (b) units derived from ethylene and optionally no more than 5.75 mole % of units derived from an alpha olefin selected from the group consisting of propene and butene at a temperature which is less than 15°C above the melting point of the polyketone polymer and maintaining the polyketone polymer composition at the melt processing temperature for less than 3 minutes; and (B) crash cooling the polyketone polymer composition at a rate of above 20°C per minute.

2. A melt processed barrier material as claimed in claim 1 wherein the polyketone polymer composition is melt processed at a temperature which is less than 5°C above the endset of melting of the polyketone polymer.

3. A melt processed barrier material as claimed in claims 1 or 2 wherein the polyketone polymer composition is crash cooled after melt processing at a rate of at least 30°C per minute.

4. A melt processed barrier material as claimed in claim 3 wherein the polyketone polymer composition is crash cooled after melt processing at a rate of at least 40°C per minute.

5. A melt processed barrier material as claimed in any one of the preceding claims wherein the oxygen permeability of the barrier material at 23°C, 75%RH is less than 0.8 x 10^"13 cc.cm cm^"2 s^"1 crnHg^"1.

6. A melt processed barrier material as claimed in any one of the preceding claims wherein the amount of units derived from propene and/or butene in the polyketone polymer is no more than 5 mol%.

7. A melt processed barrier material as claimed in any one of the preceding claims wherein the polyketone polymer includes units derived from a further alpha olefin selected from the group consisting of pentene, hexene, heptene and octene.

8. A melt processed barrier material as claimed in any one of the preceding claims wherein the ratio of CO₂ to O₂ permeability for the polyketone barrier material of the present invention is greater than 50: 1.

9. A process for preparing a barrier material having an oxygen permeability of less than

1 x 10^"13 cc.cm cm^"2 s^"1 crnHg^"1 at 23°C, 75% relative humidity (RH), which process comprises

(A) melt processing a polyketone polymer composition comprising a polyketone polymer having an alternating structure of (a) units derived from carbon monoxide, and (b) units derived from ethylene and optionally no more than 5.75 mole % of units derived from an alpha olefin selected from the group consisting of propene and butene at a temperature which is less than 15°C above the melting point of the polyketone polymer and maintaining the polyketone polymer composition at the melt processing temperature for less than 3 minutes; and (B) crash cooling the polyketone polymer composition at a rate of above 20°C per minute.

10. A process as claimed in claim 9 wherein the polyketone polymer composition is melt processed at a temperature which is less than 5°C above the melting point of the polyketone polymer.

11. A process as claimed in claims 9 or 10 wherein the polyketone polymer composition is crash cooled after melt processing at a rate of at least 30°C per minute.

12. A process as claimed in claim 11 wherein the polyketone polymer composition is crash cooled after melt processing at a rate of at least 40°C per minute.

13. A process as claimed in any one of claims 9 to 12 wherein the amount of units derived from propene and/or butene in the polyketone polymer is no more than 5 mol%.

14. A process as claimed in any one of the preceding claims wherein the polyketone polymer includes units derived from a further alpha olefin selected from the group consisting of pentene, hexene, heptene and octene.

15. A polymer-based article wherein the polymer comprises a barrier material as defined in any one of claims 1 to 8.

16. A polymer-based article as claimed in claim 15 wherein the article is of a multilayer construction, at least one layer of which is a barrier material as defined in any one of claimed 1 to 8.

17. A polymer-based film, sheet, coating, pipe, tubing or liner wherein the polymer comprises a barrier material as defined in any one of claims 1 to 8.