Polymeric materials

Abstract

Polyaryletherketones are produced which are end-capped with a phenylethynyl-containing moiety. The end-capped material, having a relatively low molecular weight, may be subjected to a thermal cycle to produce a higher molecular weight material having excellent mechanical properties, a relatively high level of crystallinity and acceptable Tm and Tg

Claims

1. A polymeric material comprising repeat unit of formula I: ##STR00018## wherein t1 and w1 independently represent 0 or 1 and v1 represents 0, 1 or 2; wherein said polymeric material has a Reduced Viscosity (RV) of at least 0.6 dL/g: and wherein the polymeric material is end-capped with a phenylethynyl-containing moiety, wherein said polymeric material is a copolymer which includes a repeat unit or formula X ##STR00019## and a repeat unit of formula XI ##STR00020##

2. A polymeric material according to claim 1, wherein the repeat units X and XI are in molar proportions X:XI of from 65:35 to 95:5.

3. A polymeric material according to claim 1, wherein said copolymer includes at least 68 mol% of repeat units of formula X and at least 10 mol% of repeat units of formula XI.

4. A method of making a component, the method comprising: (i) selecting the polymeric material as described in claim 1; and (ii) melt processing said polymeric material to form the component.

5. A method according to claim 4, wherein the RV of the melt-processed polymeric material is higher by at least 0.1 dL/g compared to the RV of said polymeric material.

6. A method according to claim 4, wherein the melt-processed polymeric material has a crystallinity of at least 20%.

7. A method according to claim 4, wherein the difference between the Tm of the polymeric material and the Tm of the melt-processed polymeric material is at least 1 C.; and the difference between the Tg of the polymeric material and the Tg of the melt-processed polymeric material is at least 2 C.

8. A composition comprising the polymeric material according to claim 1 and a filler.

9. A composition according to claim 8, wherein said polymeric material has a Tm of less than 350 C.

Description

EXAMPLE 1

Preparation of 4-FPEB-capped PEEK

(1) To a 500 mL flange flask fitted with an air condenser, nitrogen inlet and an overhead torque stirrer were added 4,4-difluorobenzophenone (BDF) (109.92 g, 0.504 mol), hydroquinone (HQ) (55.06 g, 0.50 mol), and 4-fluorophenylethynylbenzopheone (4-FPEB) (0.75 g, 0.0025 mol) and diphenylsulfone (DPS) (224 g). The flask was purged with nitrogen for 30 mins. The mixture was then heated to 160 C. and a mixture of sodium carbonate (53.26 g, 0.503 mol) sieved through a screen of mesh size 500 m and potassium carbonate (1.38 g, 0.001 mol) was added to the reaction mixture. The temperature was raised to 315 C. at 1 C. min.sup.1 and held at this temperature until the desired torque rise was reached. The required torque rise was determined from a calibration graph of torque rise versus RV. The reaction mixture was then poured into a foil tray and allowed to cool, milled and washed with 2 L of acetone and then warm water (40-50 C.) until the conductivity of the waste water was 2 S. The resulting polymer powder was dried in an air oven for 16 hours at 130 C. and had RV of 0.89 dL/g

EXAMPLES 2 TO 6

Preparation of Other End-capped PEEKs

(2) By processes similar to Example 1 other 4-FPEB-capped and 3-FPEB-capped PEEK polymers were prepared. The type and amount of end capping reagents (and BDF) used were as detailed in Table 1. Note in each example, the amounts of HQ and DPS were as described in Example 1.

(3) TABLE-US-00001 TABLE 1 End- RV of end End- capping Cross-linker capped capping reagent loading polymer Example No. reagent (mol) BDF (mol) (mol %) (dL/g) 1 4-FPEB 0.0025 0.504 0.5 0.89 2 3-FPEB 0.0025 0.504 0.5 0.94 3 4-FPEB 0.0025 0.504 0.5 1.09 4 4-FPEB 0.0025 0.504 0.5 1.21 5 4-FPEB 0.0015 0.506 0.3 1.03 6 4-FPEB 0.0015 0.506 0.3 1.24 Note: Cross-linker loading (mole %) is defined as (moles of end-capping reagent/moles of BDF) 100%.

EXAMPLE 7

Scale-up of 4-FPEB End-capped PEEK

(4) A 70 litre stainless steel reactor fitted with a lid, stirrer/stirrer guide, nitrogen inlet and outlet was charged with diphenylsulphone (DPS) (20.5 kg) and heated to 160 C. Once the diphenylsulfone had fully melted, hydroquinone (HQ) (3.85 kg, 35.00 mol) 4, 4-difluorobenzophenone (BDF) (7.73 kg, 35.44 mol) and 4-fluorophenylethynylbenzophenone (4-FPEB) (0.053 kg, 0.175 mol) were charged to the reactor under nitrogen. Dried sodium carbonate (3.73 kg, 35.18 mol) sieved through a screen with a mesh of 500 m and potassium carbonate (0.097 kg, 0.70 mol) was added. The contents were then heated to 180 C. at 1 C./min while maintaining a nitrogen blanket and held for 100 minutes. The temperature was then raised to 200 C. at 1 C./min and held for 20 minutes. The temperature was further raised to 315 C. at 1 C./min and held until the desired molecular weight was reached as determined by the torque rise of the stirrer. The required torque rise was determined from a calibration graph of torque rise versus RV. The reaction mixture was poured via a band caster into a water bath, allowed to cool, milled and washed with 400 litres of acetone and 1000 litres of water. The resulting polymer powder was dried in a tumble dryer until the contents temperature measured 110 C. The resulting end-capped polymer had RV of 1.00 dL/g.

EXAMPLES 8-11

(5) By processes similar to Example 7 other 4-FPEB-capped polymers were prepared. The amount of end capping reagent used was as detailed in Table 2.

(6) TABLE-US-00002 TABLE 2 End- RV of end End- capping Cross-linker capped capping reagent loading polymer Example No. reagent (mol) BDF (mol) (mol %) (dL/g) 7 4-FPEB 0.175 35.44 0.5 1.00 8 4-FPEB 0.175 35.44 0.5 1.14 9 4-FPEB 0.175 35.79 0.5 0.76 10 4-FPEB 0.175 35.44 0.5 1.19 11 4-FPEB 0.175 35.79 0.5 0.88 Note: In each of Examples 8 to 11, the amount of HQ and DPS were as described in Example 7. Cross-linker loading (mole %) is defined as (moles of end-capping reagent/moles of BDF) 100%.

EXAMPLE 12

Curing of Polymeric Materials

(7) Respective dried samples of polymer from examples 1-6 were compression moulded into amorphous films by heating 5 g of polymer in a mould at 400 under a pressure of 50 bar producing a film of dimensions 120 mm120 mm with a thickness of 0.2 mm. The pressure was released but the films were maintained between the platens of the press for 2 hours at 400 C. to cure the materials, before being quenched in cold water.

(8) Respective polymers from examples 7, 8 and 10 were cured by heating samples up to 400 C. and holding for 2 hours in a DSC pan according Procedure 2 below.

(9) Polymers from Examples 9 and 11 were injection moulded into test bars using an injection moulding machine with a tool temperature of 150 C., barrel temperature of 360 C., nozzle temperature of 390 C., holding pressure of 30 bar, injection pressure of 60 bar until the mould was filled then 100 bar for 10 seconds. The screwback pressure was 10 bar and the screwback speed 175 mm/s. The bars were then cured by placing them in a steel tool which was then placed between the platens of a hot press at 400 C. for 2 hours.

(10) The following further procedures are used to assess properties of materials described herein:

(11) Procedure 2Measurement of Tg, Tm, % Crystallinity

(12) A DSC analysis was undertaken on end-capped polymers made as described in the examples using a Perkin Elmer Jade system.

(13) An 8 mg sample of film from examples 1-6 obtained as described in Example 12, an 8 mg sample of polymer powder from examples 7, 8 and 10 and an 8 mg sample shaved from the injection moulded test bars from examples 9 and 11 were scanned by DSC to determine Tg and Tm as follows:

(14) Samples were heated up from 30 C. to 400 C. at 10 C. per min, held at 400 C. for 1 minute (for examples 1-6, 9 and 11) or 2 hours (examples 7, 8 and 10) then cooled back down to 100 C. at the same rate. The samples were then re-heated to 400 C. at 10 C. per min, held for 1 minute at 400 C. before cooling back again to 30 C.

(15) From the DSC trace from the second heat/cool cycle, the onset of the Tg was obtained as the intersection of the lines drawn along the pre-transition baseline and a line drawn along the greatest slope obtained during the transition. The Tm was the temperature at which the main peak of the melting endotherm reached a maximum.

(16) The Heat of Fusion for melting (Hm) was obtained by connecting the two points at which the melting endotherm deviates from the relatively straight baseline. The integrated area under the endotherm as a function of time yields the enthalpy (mJ) of the melting transition; the mass normalised heat of fusion is calculated by dividing the enthalpy by the mass of the specimen (J/g). The level of crystallisation (%) is determined by dividing the Heat of Fusion of the specimen by the Heat of Fusion of a totally crystalline polymer, which for polyetheretherketone is 130 J/g.

(17) Procedure 3Gel Time

(18) Gel time was measured using a parallel plate rheometer equipped with 25 mm plates with a 2 mm gap. A thermal sweep was performed at 400 C. over 1 hour and the gel time was determined by observing the time taken for the phase angle to pass through 45.

(19) Procedure 4Fracture Energy Density

(20) Fracture toughness testing was carried out on an Instron 3369 testing machine operating with a 30 kN load cell using a notched ASTM impact bar (8 mm notch) in accordance with ASTM D5045-99

(21) Procedure 5Tensile Testing

(22) Tensile testing was carried out on an Instron 3369 testing machine operating with a 30 kN load cell with an extension rate of 5 mm per min, 25 mm gauge length and 40 mm crosshead separation using a 1BA ISO test bar in accordance with ISO 527. Tensile strength, tensile modulus and elongation at break were determined.

(23) Results

(24) Properties of Cured Samples of Examples 1 to 6 Polymers are Included in Table 3

(25) TABLE-US-00003 TABLE 3 Post Tm Starting curing Tg post post Example RV RV cure cure Crystallinity No. (dL/g) (dL/g) ( C.) ( C.) (X %) 1 0.89 1.32 151 332 26 2 0.94 1.65 154 326 24 3 1.09 1.04 150 331 28 4 1.21 1.29 148 334 31 5 1.03 1.58 149 333 31 6 1.24 1.59 151 331 29

(26) Properties of cured samples of Examples 7 to 10 polymers are included in Table 4. The post-cured RV was not measured on Examples 7, 8 and 10 as films were not prepared. The samples were cured during the DSC process. Only a small (8 mg) sample was used which was not sufficient for RV measurement. Nonetheless, the results do demonstrate an increase in Tg and decrease in Tm on curing.

(27) TABLE-US-00004 TABLE 4 Tm Starting Tg post post Example RV cure cure Crystallinity No. (dL/g) ( C.) ( C.) (X %) 7 1.00 150 328 20 8 1.14 151 315 19 10 1.19 150 318 21

(28) Properties of the moulded samples of Examples 9 and 11 were assessed and results are provided in Table 5.

(29) TABLE-US-00005 TABLE 5 Starting Post Tg post Tm post Crystal- Gel time Exam- RV moulding cure cure linity @ 400 ple No. (dL/g) RV (dL/g) ( C.) ( C.) (X %) C.(mins) 9 0.76 0.90 137 340 39 27 11 0.88 1.24 145 334 28 6

(30) Mechanical properties of moulded samples were assessed and compared to commercially available PEEK 90, PEEK 150 and PEEK 450 materials. Results are provided in Table 6.

(31) TABLE-US-00006 TABLE 6 Fracture RV pre Energy Tensile Tensile Elongation Example moulding density strength Modulus at break No. (dL/g) (kJm2) (MPa) (GPa) (%) 9 0.76 3.0 106 4.3 13 11 0.88 7.0 106 4.4 76 PEEK 90 0.76 1.5 106 4.3 19 PEEK 150 0.88 4.0 103 4.1 17 PEEK 450 1.21 10.0 106 4.3 98

(32) It will be appreciated from Table 6, that moulding the example 9 polymer having the same starting RV as PEEK 90, yields a polymer with properties more like PEEK 150. Similarly, Example 11, having the same starting RV as PEEK 150, has properties after moulding which are more like PEEK 450.

(33) Advantageously, it is found that the shear heating and injection moulding process promotes the majority of the curing of the polymers and thus an increase in RV and improved properties. A post-cure step (e.g. heating at 400 C. for 2 hours) is not found to lead to a significant further increase in fracture toughness over as moulded samples.

(34) Alternative phenylethynyl compounds which may be used as described above for 4-FPEB include the following:

(35) ##STR00017##

(36) RF or Cl

(37) It should now be appreciated that the phenylethynyl compounds described can be used to improve mechanical properties of the polymers described whilst maintaining high levels of crystallinity. The polymer described may be used to produce thin walled parts by injection mouldingthe relatively low RV polymer will be selected to flow into narrow sections of the mould; however during the moulding process (and/or thereafter) the RV of the polymer may be increased, whilst still maintaining substantial crystallinity. Alternatively, relatively low RV polymers may be used to produce highly-filled compounds. After mixing of the polymers and fillers, the RV of the polymer may be increased to enhance its physical properties whilst still retaining high levels of crystallinity.

(38) The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.