Polymeric materials

Abstract

An assembly or apparatus for use in relation to an assembly, wherein said assembly is subjected to a temperature of less than 50 C. in use, wherein said assembly or apparatus includes a component which comprises a polymeric material (A) having a repeat unit of formula O-Ph-O-Ph-CO-Ph- (I) wherein Ph represents a phenylene moiety; and wherein said polymeric material (A) has a melt viscosity of at least 0.50 kNsm.sup.2.

Claims

1. An assembly or apparatus for use in relation to an assembly, wherein said assembly is subjected to a temperature of less than 100 C. in use, wherein said assembly or apparatus includes a component which comprises a polymeric material (A) having a repeat unit of formula ##STR00003## wherein said polymeric material (A) includes at least 80 mol % of repeat units of formula II; and wherein said polymeric material (A) has a melt viscosity of at least 0.50 kNsm.sup.2.

2. An assembly or apparatus according to claim 1, wherein said assembly or apparatus and/or wherein said component is subjected to a temperature of less than 140 C. in use.

3. An assembly or apparatus according to claim 1, wherein said assembly is associated with liquid natural gas handling, transport or storage.

4. An assembly or apparatus according to claim 1, wherein said assembly is a liquid natural gas storage tank or a part associated therewith, or wherein said component is a part of a liquid natural gas storage tank or a part associated therewith.

5. An assembly or apparatus according to claim 1, wherein said component is selected from the group consisting of a seal, a valve, a part of a valve, a gasket, a bearing, a part of a bearing, a housing, a ring, a pipe, a part of a pipe, a pipe liner, a connector, insulation, and a bush.

6. An assembly or apparatus according to claim 1, wherein said polymeric material (A) has a melt viscosity of at least 0.60 kNsm.sup.2.

7. An assembly or apparatus according to claim 1, wherein said polymeric material (A) has a melt viscosity in a range 0.55 to 0.75 kNsm.sup.2.

8. An assembly or apparatus according to claim 1, wherein said component includes at least 95 wt % of said polymeric material (A).

9. An assembly or apparatus according to claim 1, wherein said polymeric material (A) is manufactured by aromatic nucleophilic substitution, wherein said aromatic nucleophilic substitution comprises reacting a nucleophile with a 4,4-difluorobenzophenone monomer, and wherein said 4,4-difluorobenzophenone monomer has a purity of at least 99.7% w/w by difference, as measured using HPLC-UV analysis.

10. A method of making a component for an assembly or apparatus as described in claim 1, the method comprising: (i) selecting the polymeric material (A); (ii) melt processing the polymeric material (A); (iii) forming said component during and/or after step (ii).

11. A method according to claim 10, wherein step (ii) comprises extrusion or injection moulding.

12. A liquid natural gas assembly which comprises a component as described in claim 1.

13. An assembly according to claim 12, said assembly being associated with liquid natural gas handling, transport or storage.

14. An assembly according to claim 13, wherein said assembly is a liquid natural gas storage tank and/or a part associated therewith.

Description

(1) Specific embodiments of the invention will now be described, by way of example, with reference to the accompanying figures, in which:

(2) FIG. 1 is a plot of log MFI v. Melt Viscosity for a series of polymers.

(3) FIGS. 2 to 6 provide respective results of tensile strength, tensile modulus, tensile elongation, flexural strength and un-notched Charpy Impact of two different PEEK polymers at two different temperatures;

(4) FIG. 7 provides results for tensile elongation for two different PEEK polymers and PTFE at two different temperatures;

(5) FIG. 8 is a plot of stress v. strain for PEEK 450G at 196 C.;

(6) FIG. 9 is a plot of stress v. strain for a polymer referred to herein as PEEK EG3 at 196 C.

(7) The following materials are referred to hereinafter:

(8) PEEK 450GPEEK polymer in granule form commercially available from Victrex Plc, Thornton Cleveleys, UK. The polymer has an MV of 0.45 kNsm.sup.2 when measured as described in Test 1.

(9) PTFETeflon PTFE in mechanical grade sheet form commercially available from Professional Plastics, Inc.

(10) PCTFEKel-F PCTFE in sheet form commercially available from Professional Plastics, Inc.

(11) The following tests are used in the examples which follow.

(12) Test 1Melt Viscosity of Polyaryletherketones

(13) Melt Viscosity of polyaryletherketones was measured using a ram extruder fitted with a tungsten carbide die, 0.5 mm (capillary diameter)3.175 mm (capillary length). Approximately 5 grams of the polyaryletherketone was dried in an air circulating oven for 3 hours at 150 C. The extruder was allowed to equilibrate to 400 C. The dried polymer was loaded into the heated barrel of the extruder, a brass tip (12 mm long9.920.01 mm diameter) placed on top of the polymer followed by the piston and the screw was manually turned until the proof ring of the pressure gauge just engages the piston to help remove any trapped air. The column of polymer was allowed to heat and melt over a period of at least 5 minutes. After the preheat stage the screw was set in motion so that the melted polymer was extruded through the die to form a thin fibre at a shear rate of 1000 s.sup.1, while recording the pressure (P) required to extrude the polymer. The Melt Viscosity is given by the formula

(14) $\mathrm{Melt}\mathrm{Viscosity}=\frac{P{r}^4}{8\mathrm{LSA}}{\mathrm{kNsm}}^{-2}$

(15) where P=Pressure/kN m.sup.2 L=Length of die/m S=ram speed/m s.sup.1 A=barrel cross-sectional area/m.sup.2 r=Die radius/m

(16) The relationship between shear rate and the other parameters is given by the equation:

(17) $\mathrm{Apparent}\mathrm{wall}\mathrm{shear}\mathrm{rate}=1000s^{-1}=\frac{4Q}{r^3}$

(18) where Q=volumetric flow rate/m.sup.3 s.sup.1=SA.

(19) Test 2Melt Flow Index of Polyaryletherketones

(20) The Melt Flow Index of the polyaryltherketone was measured on a CEAST Melt Flow Tester 6941.000. The dry polymer was placed in the barrel of the Melt Flow Tester apparatus and heated to 380 C., this temperature being selected to fully melt the polymer. The polymer was then extruded under a constant shear stress by inserting a weighted piston (5 kg) into the barrel and extruding through a tungsten carbide die, 2.095 mmbore8.000 mm. The MFI (Melt Flow Index) is the mass of polymer (in g) extruded in 10 minutes.

(21) Test 3HPLC-UV Analysis of 4,4-Difluorobenzophenone

(22) The HPLC method is carried out on an Agilent 1220 Infinity LC system. The analysis conditions were:

(23) Mobile Phase: ALaboratory Supply Deionised Water BLC grade Methanol

(24) Gradient:

(25) TABLE-US-00001 Time B Flow (min) (%) (mL/min) 0 55 0.5 28 55 0.5 50 80 0.5 52 55 0.5 60 55 0.5

(26) Column: Thermo Hypurity C18 (or equivalent) 2504.6 mm (22103254630) Guard cartridge, C18 104.0 mm (22103014001)

(27) Column Temperature: 50 C.

(28) Injection Volume: 20 uL

(29) UV detector: 255 nm and 293 nm, spectra collection enabled

(30) The sample was prepared by dissolving 100 mg+/10 mg of DFBP in 10 ml of methanol. 100 L of this solution was transferred to an LC vial containing 900 L 60:40 methanol/water.

(31) The amounts of monofluorobenzopheone (MFB), 2,4-difluorobenzopheone (2,4 BDF), 4,4-difluorobenzophenone (4,4 BDF), 4-fluoro-4-chlorobenzopenone and 4-fluoro-4-nitrobenzophenone were determined using a calibration with external standards of different concentrations to generate a calibration curve.

(32) Calibrated Peak Table:

(33) TABLE-US-00002 Detection Reten- Typical r.sup.2 Wave- tion linear length Time (typical Component (nm) (min) calibration) 2,4-difluorobenzophenone 255 29.0 0.9999 Monofluorobenzopheone 255 30.6 0.9999 4,4-difluorobenzophenone 255 34.0 0.9999 4-fluoro-4-chlorobenzopenone 255 47.7 0.9999 4-fluoro-4-nitrobenzophenone 255 53.3 0.9999
Results are expressed as % w/w of the impurities.

(34) The purity is quoted (see infra) as a % w/w of 4,4-BDF by difference.

(35) Test 4Melting Point Range Determination

(36) The melting point range is determined automatically by optical transmission measurement using a Bchi B-545. The first value is recorded at 1 percent transmission.

(37) Settings:

(38) gradient: 1 C./min Set point: 101 C. mode: Pharmacopoe detection: 1 and 90 percent

(39) The melting point range is recorded as the difference between 90 and 1 percent of melting point determination.

(40) Test 5Colour Measurements

(41) Colour measurements were carried out on injection moulded ISO test bars of selected PEEK polymers prepared as described herein. Standard type 1A ISO test bars (ISO 3167) were injection moulded using on a Haitian injection moulding machine with a barrel temperature of 320 C.-335 C., nozzle temperature of 335 C. and a tool temperature of 160 C.

(42) The measurements were made using a Konica Minolta Chromameter with a DP400 data processor operating over a spectral range of 360 nm to 750 nm. A white plate calibration was carried out with a D65 (natural daylight) light source. Colour measurements are expressed at L*, a* and b* coordinates as defined by the CIE 1976 (Nassau, K. Kirk-Othmer Encyclopaedia of Chemical Technology, chapter 7, page 303-341, 2004). Values were determined from a single point on the ISO test bar.

(43) Test 6Measurement of Tc by DSC

(44) The crystallisation temperature from the melt (Tc) for selected PEEK polymers prepared as described herein was determined by Differential Scanning calorimetry.

(45) A dried sample of each polymer was compression moulded into an amorphous film, by heating 7 g of polymer in a mould at 400 C. under a pressure of 50 bar for 2 minutes, then quenching in cold water producing a film of dimensions 120120 mm, with a thickness in the region of 0.20 mm. An 8 mg plus or minus 3 mg sample of each film was scanned as follows: Step 1 Perform a preliminary thermal cycle by heating the sample from 30 C. to 400 C. at 20 C./min. Step 2 Hold for 2 mins. Step 3 Cool at 20 C./min to 30 C. and hold for 5 mins. Step 4 Heat from 30 C. to 400 C. at 20 C./mins.

(46) From the resulting scan the Tc was the temperature at which the main peak of the crystallisation from the melt reached a maximum.

(47) In the following description, 4,4-difluorobenzophenone (BDF) used to prepare polyetheretherketone (PEEK) for use in low temperature applications is described in Example 1. For comparison, BDF made by a different method is described in Example 2. Procedures for making PEEK are described in Examples 3 and 4. PEEK polymers prepared are tested using the tests described above, and results reported and discussed.

EXAMPLE 1PREPARATION OF 4,4-DIFLUOROBENZOPHENONE (BDF) BY REACTING FLUOROBENZENE AND 4-FLUOROBENZOYLCHLORIDE

(48) A 10 liter 3-necked round-bottomed flask fitted with a mechanical stirrer, a thermometer, a dropping funnel containing 4-fluorobenzoyl chloride (1550 g, 9.78 moles) and a reflux condenser was charged with fluorobenzene (2048 g, 21.33 moles) and anhydrous aluminium trichloride (1460 g, 10.94 moles). The mixture was maintained at 20 to 30 C. with stirring and the 4-fluorobenzoylchloride was added dropwise over a period of 1 hour. When the addition was complete the temperature of the reaction mixture was increased to 80 C. over a period of 2 hours, allowed to cool to ambient temperature then carefully discharged into ice(4 kg)/water(2 kg). The mixture was recharged to a 20 l 1-necked round-bottomed flask fitted with distill head. The contents were heated to distill off the excess fluorobenzene until a still-head temperature of 100 C. was reached. The mixture was cooled to 20 C. and the crude 4,4-difluorobenzophenone was filtered off, washed with water and dried at 70 C. under vacuum.

(49) The crude product was recrystallised as follows: Dry crude product (100 g) was dissolved with stirring in hot industrial methylated spirits (400 cm.sup.3) and charcoal, filtered, water (100 cm.sup.3) was added, reheated to reflux to dissolve the product and then cooled. The product was filtered off, washed with 1:1 industrial methylated spirits/water then dried at 70 C. under vacuum. The product had a melting point range of 107-108 C. determined using Test 4 and a 4,4-difluorobenzophenone purity of greater than 99.90% determined using Test 3. Details on the purity are provided below for three replicates of Example 1 (referred to as Examples 1 a, 1b and 1c).

(50) TABLE-US-00003 4,4BDF 2,4BDF MFB 4F,4Cl 4,4DCBP 4,4 FNBP (% w/w by Example (% w/w) (% w/w) (% w/w) (% w/w) (% w/w) difference) Example 1a 0.005 0.027 N/D N/D N/A 99.97 Example 1b 0.004 0.026 <0.001 <0.001 N/A 99.97 Example 1c 0.003 0.019 0.002 N/D N/A 99.98

EXAMPLE 2 (COMPARATIVE)PREPARATION OF 4,4-DIFLUOROBENZOPHENONE (BDF) BY THE NITRIC ACID OXIDATION OF 4,4-DIFLUORODIPHENYLMETHANE

(51) The process described in Example 2 of EP 4710 A2 for the oxidation of 4,4-difluorodiphenylmethane was followed except the scale was increased by a factor of 3.

(52) Following the recrystallisation procedure described in Example 2 of EP 4710 A2, 4,4-determined (115 g) with a melting point range 106-107 C. and a purity of about 99.6%, determined using Test 3. Details on the purity are provided below for two replicates of Example 2 (referred to as Examples 2a and 2b).

(53) TABLE-US-00004 4,4BDF 2,4BDF MFB 4F,4Cl 4,4DCBP 4,4 FNBP (% w/w by Example (% w/w) (% w/w) (% w/w) (% w/w) (% w/w) difference) Example 2a N/A 0.32 N/A N/A 0.06 99.62 Example 2b N/A 0.38 N/A N/A 0.05 99.57

EXAMPLE 3PREPARATION OF POLYETHERETHERKETONE

(54) A 3 L vessel fitted with a ground glass Quickfit lid, stirrer/stirrer guide, nitrogen inlet and outlet was charged with 4,4-difluorobenzophenone from Example 1 (269.76 g, 1.236 mole), hydroquinone (133.2 g, 1.2 mole) and diphenylsulphone (600 g) and purged with nitrogen for over 1 hour. The contents were then heated to between 140 and 150 C. to form an almost colourless solution. Dried sodium carbonate (127.32 g, 1.2 mole) and potassium carbonate (3.336 g, 0.0242 mole) were added. The temperature was raised to 200 C. and held for 1 hour; raised to 250 C. and held for 1 hour; raised to 315 C. and maintained for 2 hours or until the required melt viscosity 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 MV. The reaction mixture was then poured into a foil tray, allowed to cool, milled and washed with 2 liters of acetone and then with warm water at a temperature of 40-50 C. until the conductivity of the waste water was <2 S. The resulting polymer powder was dried in an air oven for 12 hours at 120 C. The MV of the resulting polymer was 0.65 kNsm.sup.2 measured according to Test 1.

EXAMPLES 4PREPARATION OF SAMPLES OF POLYETHERETHERKETONE FROM DIFFERENT SOURCES OF 4,4-DIFLUOROBENZOPHENONE (BDF) AND AT A RANGE OF MELT VISCOSITIES

(55) The procedure described in Example 3 was repeated except the source of 4,4-difluorobenzophenone was varied as between that described in Example 1 and in Example 2 and the polymerisation time was varied to produce polyetheretherketone with a range of melt viscosities. The Melt Viscosity and Melt Flow Index of a range of products were assessed and a relationship between Melt Viscosity and Melt Flow Index determined.

(56) It was found that the following relationship applied to PEEK of different melt viscosities prepared from the BDF described in Example 1:
Log.sub.10 MFI=2.342.4Melt Viscosity

(57) It was found that the following relationship applied to PEEK of different melt viscosities prepared from the BDF described in Example 2:
Log.sub.10MFI=2.2353.22Melt Viscosity

(58) where MFI and melt viscosity were determined as described in Tests 1 and 2.

(59) For illustrative purposes, the equations referred to are represented in FIG. 1 for MV from about 0.40 to 0.70 kNsm.sup.2.

(60) It should be appreciated from FIG. 1 that the MFI of the PEEK prepared from Example 1 monomer is significantly higher than for the PEEK prepared from Example 2 monomer. In addition, as described hereinafter, other properties of PEEK prepared from the Example 1 monomer are advantageous and make such PEEK polymer highly suited for use in very low temperature applications.

(61) Results from Tests 5 and 6 for colour and Tc for PEEK polymers made from the BDF of Examples 1 and 2 are provided in the tables below from which it is clear that there are significant differences between the two types of polymers.

(62) TABLE-US-00005 BDF from PEEK Colour Example L* a* b* 1a 60.94 1.84 9.86 1b 60.76 1.82 9.35 1c 61.89 1.80 7.86 2a 58.94 2.16 7.42 2b 58.22 2.25 7.98

(63) TABLE-US-00006 BDF from PEEK Tc Example ( C.) 1a 283.3 1b 283.5 1c 282.7 2a 289.9 2b 289.3

(64) PEEK 450G (comparative) and PEEK prepared as described in Example 3 using the BDF described in Example 1 and having a Melt Viscosity assessed as described in Example Test 1 of 0.65 kNsm.sup.2 (herein referred to as PEEK EG3) were tested for their suitability for use in low temperature applications as discussed further below.

(65) Details on the tests undertaken are described below. In general, tests were undertaken at ambient temperature (23 C.) and at very low temperature (77K; 196 C.) using liquid nitrogen.

(66) Bending Tests

(67) These were carried out according to ISO 178 in liquid nitrogen. In the case of large deformations, the strains and stresses were corrected according to ISO-14125.

(68) Tensile Tests

(69) Tensile tests according to ISO 527 were carried out using a special test fixture (INCONEL 718) suitable for liquid nitrogen temperatures.

(70) Impact Tests

(71) Charpy Impact tests were made on un-notched samples according to ISO 179-1: 2010 using a Dynatup 9250HV drop tower.

(72) Results for tensile strength, tensile modulus, tensile elongation, flexural strength and un-notched Charpy Impact for PEEK 450G and PEEK EG3 at 23 C. and 196 C. are provided in FIGS. 2 to 6. It will be noted that PEEK EG3 generally has significantly superior properties over PEEK 450G at 196 C.

(73) FIG. 7 provides a comparison of tensile elongation for PEEK 450G, PEEK EG3 and commercially available PTFE. It will be noted that PEEK EG3 has superior low temperature properties compared to the other polymers.

(74) To assess the ductility of PEEK 450G and PEEK EG3 at 196 C., stress-strain curves for the two polymers were constructed at the aforementioned temperature. The curves for PEEK 450G and PEEK EG3 are provided in FIGS. 8 and 9 respectively.

(75) Comparing FIGS. 8 and 9, it should be noted that 450G material does not significantly yield at 196 C. and fails at relatively low strains (about 6%); whereas FIG. 9 shows significant yielding at higher strains before the specimen failurethat is, it shows ductility up to about 11% strain.

(76) The fracture surfaces of tensile bars used in constructing the curves of FIGS. 8 and 9 were examined. For the PEEK 450G bars assessed, there was little evidence of yielding since the fracture surfaces were found to be fairly smooth. There is some evidence of cleavage stop which are structures which indicate the direction of crack propagation and which cause the crack to divide into several fracture paths which recombine as the fracture progresses. In contrast, for the PEEK EG3 bars, there is clear evidence of ductility. In ductile thermoplastic failures, the load causes macromolecules to stretch and, as a fracture progresses, the elongated stretched areas (as they break) recoil showing peaks which have stretched and which are sometimes slightly thicker at their ends.

(77) The strain at break for PEEK EG3 is even higher than reported for PTFE or PCTFE which are currently widely used commercially for seals which are to be subjected to very low temperatures. Furthermore, the PEEK EG3 polymer is found to have higher tensile and flexural strengths compared to the fluoropolymer materials meaning that usage loads (e.g. sealing forces) may be higher for the PEEK EG3 polymer. Additionally, the PEEK EG3 polymer enjoys excellent chemical resistance properties and, generally, has been shown to have improved wear and erosion resistance compared to fluoropolymers.

(78) The samples tested to generate the results shown in FIGS. 2-9 were prepared via direct injection moulding rather than machining from solid stock shapes of polymer.

(79) Further Testing

(80) Two further batches of PEEK EG3 polymer were prepared following example 3 above. Injection moulded samples were prepared from these two batches and tested alongside injection moulded PTFE, PCTFE and PEEK 450G samples in a number of bending, tensile, compressive and impact tests at 196 C. A further batch of PEEK EG3 polymer was prepared (following example 3 above) and formed into solid stock shapes (plates) which were machined/milled to provide samples. These Machined PEEK EG3 samples were tested in the same bending, tensile, compressive and impact tests at 196 C.

(81) Machined samples were prepared and tested in order to evaluate if machining/milling has any detrimental effect on mechanical properties. Very low temperature sealing applications commonly use seals that have been precision machined from solid stock shapes of polymer (e.g. PCTFE and PTFE seals). Detrimental effects are often seen in material testing, where machined samples can exhibit lower strength and elongation at break because of micro-cracks left behind by the machining process. The Machined PEEK EG3 samples therefore more closely mimic the properties which one might expect from an article which had been machined rather than moulded.

(82) The bending tensile, and impact tests were carried out as detailed above and the compressive tests were carried out according to ISO 604. Results for flexural strength, flexural modulus, tensile strength, tensile modulus, tensile elongation, compressive strength, compressive modulus and un-notched Charpy impact strength of PTFE, PCTFE, PEEK 450G, PEEK EG3 and Machined PEEK EG3 samples at 196 C. are shown in the tables below:

(83) TABLE-US-00007 Flexural Flexural Tensile Tensile Tensile Strength Modulus Strength Modulus Elongation Sample (MPa) (GPa) (MPa) (GPa) (%) PTFE 183.70 6.431 90.21 5.720 3.28 PCTFE 265.93 5.697 128.03 5.064 3.31 PEEK 450G 417.45 5.818 194.69 5.346 5.10 PEEK EG3 434.43 5.475 221.75 5.184 9.28 Machined PEEK 432.93 5.735 221.77 5.492 8.41 EG3

(84) TABLE-US-00008 Compressive Compressive Charpy Impact Strength Modulus Strength Sample (MPa) (GPa) (kJm.sup.2) PTFE 204.40 6.229 62.88 PCTFE 319.50 5.013 45.96 PEEK 450G 322.49 5.078 172.82 PEEK EG3 320.76 4.882 193.74 Machined PEEK 313.16 5.050 209.64 EG3

(85) Tables of Mechanical Test Results for PTFE, PCTFE, PEEK 450G, PEEK EG3 and Machined PEEK EG3 Samples at 196 C.

(86) Repeat tests were conducted for each type of test (i.e. Flexural Strength, Flexural Modulus etc.). The values in the above tables are averaged values calculated, for each type of test, from: five tests for PTFE; five tests for PCTFE; five tests for each of two batches for PEEK 450G except for the compressive strength and compressive modulus tests which were averaged from five tests for one batch only; five tests for each of two batches for PEEK EG3 except for the compressive strength and compressive modulus tests which were averaged from five tests for one batch only; and nine tests for Machined PEEK EG3 except for the tensile strength, tensile modulus and tensile elongation tests which were averaged from five tests, and the compressive modulus test which was averaged from six tests.

(87) The results show that both the PEEK EG3 and Machined PEEK EG3 samples exhibit higher flexural and tensile strength compared to samples of the incumbent materials. This indicates that components used in accordance with the present invention possess a higher loading potential and therefore a greater safety margin with regard to breakage.

(88) The PEEK EG3 and Machined PEEK EG3 samples also exhibit higher un-notched Charpy impact strength than the comparative samples. This indicates a tougher product offering higher resilience and consequently a higher factor of safety.

(89) The PEEK EG3 and Machined PEEK EG3 samples exhibit equivalent compressive strength to the PCTFE and PEEK 450G samples, and far greater compressive strength than the PTFE samples.

(90) The flexural, tensile and compressive modulus values of the PEEK EG3 samples are lower than for any of the other samples except for the PCTFE tensile modulus value. Lower values indicate that the PEEK EG3 samples are more flexible at low temperature, and therefore require lower loads to deform i.e. a lower force would be required to form a seal.

(91) Additionally, the tensile elongation values that the PEEK EG3 and Machined PEEK EG3 samples exhibit are far higher than those for the comparative samples. This indicates that components used in accordance with the present invention have significantly higher ductility and hence would provide more robust performance at low temperature.

(92) It is also worth noting that the Machined PEEK EG3 samples provide equivalent results to the PEEK EG3 (i.e. injection moulded) samples in all of the tests, indicating that machining/milling at most has a minor effect on mechanical properties.

(93) Ring Compression Test

(94) This test is designed to simulate the compression of a seal by a steel ball in a real application, e.g. this is what occurs during the operation of a quarter turn ball valve. In such a valve the ball has a hole through its centre. When in the open position, fluid can flow through the centre of the ball. When the handle is turned a quarter turn the hole in the ball is no longer accessible and the flow ceases. In such a valve, the ball is held in place by a valve seat which has a seal. In the test a 50 mm diameter valve seat was machined to mate with a steel bearing. A ring shaped seal for the valve seat was prepared from each of PTFE, PCTFE, PEEK 450G and PEEK EG3. To test the seal in question the seal was fitted into the valve seat and the bearing was slowly compressed into the seal. The load displacement response of the seal was evaluated at 7 kN compressive load and the residual displacement on removal of the load was measured to assess recovery. The tests were conducted at 196 C. The results are shown in the below table in which the values are averages calculated from five samples for each material for each test:

(95) TABLE-US-00009 Maximum Displacement at Residual Displacement 7 kN Compressive Load on Removal of Load Sample (mm) (mm) PTFE 0.71 0.33 PCTFE 0.51 0.14 PEEK 450G 0.48 0.12 PEEK EG3 0.52 0.14
Table of Ring Compression Test Results for PTFE, PCTFE, PEEK 450G and PEEK EG3 samples at 196 C.
The results demonstrate that the PEEK EG3 ring retains its shape at 196 C. in a similar way to the PCTFE and PEEK 450G materials. Furthermore, when the load is removed, the PEEK EG3 material recovers its original form much more quickly than PTFE and similarly to PCTFE and PEEK 450G (residual displacement on removal of load). It is a desirable property for the sealing materials to spring back quickly (especially at very low temperatures) as it ensures that the material is always ready to remake a new seal. It is notable that PTFE does not spring back quickly, having more than twice the residual displacement of PEEK EG3 and PCTFE. These results illustrate that components used in accordance with the present invention have good low temperature sealing properties.

(96) The PEEK EG3 polymeric material may have wide ranging uses. For example, it may be used for parts or components which may be subjected to low temperatures in use, for example at or below cryogenic temperatures. The polymer may be used for parts or components associated with LNG storage tanks. The polymer may be used for parts or components which are to be used in polar regions, for example in or associated with oil and/or gas installations. Examples of uses of the PEEK EG3 polymer include: seals, in general e.g. valve seals, valve stem seals, butterfly valve seals, spring energised seals; seals of a seal stack, seal backup rings; valves or parts thereofe.g. ball valve seats, check valve seats, valve plates such as compression valve plates, valve spindles, rotary valves, valve actuators such as a solenoid valve; gaskets; bearingse.g. thrust bearings; housingse.g. for sensors; ringse.g. piston, packing, throttle or wiper rings; pipese.g. for aerospace or oil and gas applications or other conduits for fluid transport; pipe liners; connectors; wire and cable jacketing/insulation; bushings.

(97) 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.