BONDING FILMS

Abstract

Bonding films comprising PEEK-PEoEK copolymers are compatible with polyaryletherketone chemistry thereby providing joined polyaryletherketone polymer parts with high fracture toughness and overall good mechanical properties.

Claims

1. An assembly comprising a first component comprising a polymer (P1), a second component comprising a polymer (P2) and a film comprising at least one PEEK-PEoEK copolymer, the PEEK-PEoEK copolymer comprising at least 50 mol. %, collectively, of repeat units (R.sub.PEEK) and repeat units (R.sub.PEoEK), relative to a total number of moles of repeat units in the PEEK-PEoEK copolymer, wherein: repeat units (R.sub.PEEK) are repeat units of formula: ##STR00015## and repeat units (R.sub.PEoEK) are repeat units of formula: ##STR00016## where each R.sup.1 and R.sup.2, equal to or different from each other, is at each occurrence independently selected from the group consisting of halogen, alkyl, alkenyl, alkynyl, aryl, ether, thioether, carboxylic acid, ester, amide, imide, alkali or alkaline earth metal sulfonate, alkyl sulfonate, alkali or alkaline earth metal phosphonate, alkyl phosphonate, amine, and quaternary ammonium; each a and b is independently selected from integers ranging from 0 to 4; the PEEK-PEoEK copolymer comprises the repeat units (R.sub.PEEK) and (R.sub.PEoEK) in a molar ratio (R.sub.PEEK)/(R.sub.PEoEK) ranging from 95/5 to 5/95; and said film being positioned between and bonded to said first and second component.

2. The assembly of claim 1, wherein the repeat units (R.sub.PEEK) are repeat units of formula: ##STR00017## and/or the repeat units (R.sub.PEoEK) are repeat units of formula: ##STR00018##

3. The assembly of claim 1 wherein the PEEK-PEoEK copolymer has a molar ratio (R.sub.PEEK)/(R.sub.PEoEK) in the range from 90/10 to 55/45.

4. The assembly of claim 1 wherein the PEEK-PEoEK copolymer has a melting temperature (T.sub.m) of less than or equal to 320? C., as measured according to a described method.

5. The assembly of claim 1 wherein the PEEK-PEoEK copolymer has a solubility of below 0.2% wt in N-methylpyrrolidone (NMP), N,N-dimethylacetamide (DMAc) and N,N-dimethylformamide (DMF), when determined at a temperature of 150? C. or less.

6. The assembly of claim 1, wherein the film has thickness of from 15 to 800 ?m.

7. (canceled)

8. The assembly of claim 1, wherein polymer (P1) and polymer (P2) are independently selected from the group consisting of polyaryletherketones, polyamides, polyetherimides, polyamideimides, polysulfones, polyethersulfones, polyarylethers, polycarbonates, liquid crystal polymers, polyphenylene sulfides, polyarylenes (polyphenylenes), polyphthalamides, polyaromatic esters, and blends thereof.

9. The assembly of claim 1, wherein polymer (P1) and polymer (P2) are independently selected from the group consisting of polyaryletherketones, polyetherimides, polyamideimides, polysulfones, polyethersulfones, polyphenylene sulfides, polyphthalamides, and blends thereof.

10. The assembly of claim 1 wherein polymer (P1) and polymer (P2) are independently selected from PEKKs polymer with a T/I ratio in a range from 55/45 to 85/15.

11. The assembly of claim 1 wherein the first component is a composite material comprising one or more layers comprising fibers and polymer (P1) and/or the second component is a composite material comprising one or more layers comprising fibers and polymer (P2).

12. The assembly of claim 11 wherein the fibers are carbon or glass fibers.

13. A method of making the assembly of claim 1 which comprises steps of: arranging the film between a first component comprising a polymer (P1) and a second component comprising a polymer (P2); and subjecting the film to a temperature (T.sub.m.sup.x), wherein the temperature (T.sub.m.sup.x) is suitable to melt the film but not to melt polymer (P1) and polymer (P2).

14. The method of claim 13 wherein temperature (T.sub.m.sup.x) is greater than the melting temperature of the film and lower than the melting temperature of polymer (P1) and polymer (P2).

15. The method of claim 13 which further comprises the steps of: arranging the film between a first component comprising a polymer (P1) and a second component comprising a polymer (P2); and subjecting the film to a temperature (T.sub.m.sup.x) within the range 280? C. to 315? C.

16. The method of claim 13 wherein, whilst the film is being subjected to said temperature (T.sub.m.sup.x), pressure is applied to consolidate the components.

Description

EXAMPLES

Raw Materials

[0101] 1,2-dichlorobenzene, terephthaloyl chloride, isophthaloyl chloride, 3,5-dichlorobenzoylchloride, aluminum chloride (AlCl.sub.3), methanol were purchased from Sigma Aldrich.

[0102] 1,4-Bis(4-phenoxybenzoyl)benzene was prepared according to IN patent 193687 (filed on Jun. 21, 1999 and incorporated herein by reference).

[0103] Hydroquinone, photo grade, was procured from Eastman, USA. It contained 0.38 wt % moisture, which amount was used to adapt the charge weights. All weights indicated include moisture.

[0104] Resorcinol, ACS reagent grade, was procured from Aldrich, USA

[0105] 4,4-Biphenol, polymer grade, was procured from SI, USA.

[0106] Pyrocatechol, flakes, was procured from Solvay USA. Its purity was 99.85% by GC. It contained 680 ppm moisture, which amount was used to adapt the charge weights. All weights indicated include moisture.

[0107] 4,4-Difluorobenzophenone, polymer grade (99.8%+), was procured from Malwa, India

[0108] Diphenyl sulfone (polymer grade) was procured from Proviron (99.8% pure).

[0109] Sodium carbonate, light soda ash, was procured from Solvay S.A., France.

[0110] Potassium carbonate with a d.sub.90<45 ?m was procured from Armand products.

[0111] Lithium chloride (anhydrous grade) was procured from Acros.

[0112] 1,4-bis(4-fluorobenzoyl)benzene (1,4-DFDK) and 1,3 bis(4-fluorobenzoyl)benzene (1,3-DFDK) were prepared by Friedel-Crafts acylation of fluorobenzene according to Example 1 of U.S. Pat. No. 5,300,693 to Gilb et al. (incorporated herein by reference in its entirety). Some of the 1,4-DFDK was purified as described in U.S. Pat. No. 5,300,693 by recrystallization in chlorobenzene, and some of the 1,4-DFDK was purified by recrystallization in DMSO/ethanol. The 1,4-DFDK purified by recrystallization in DMSO/ethanol was used as the 1,4-DFDK in the polymerization reactions to make PEKK described below, while 1,4-DFDK recrystallized in chlorobenzene was used as precursor for 1,4-bis(4-hydroxybenzoyl)benzene (1,4-BHBB).

[0113] 1,4-BHBB and 1,3-bis(4-hydroxybenzoyl)benzene (1,3-BHBB) were produced by hydrolysis of the 1,4-DFDK, and 1,3-DFDK, respectively, following the procedure described in Example 1 of U.S. Pat. No. 5,250,738 to Hackenbruch et al. (incorporated herein by reference in its entirety). They were purified by recrystallization in DMF/ethanol.

Determination of the Melting Temperature (T.SUB.m.), Crystallization Temperature (Tc) and Heat of Fusion

[0114] The melting temperature T.sub.m was determined as the peak temperature of the melting endotherm on the 2.sup.nd heat scan in differential scanning calorimeter (DSC) according to ASTM D3418-03, E1356-03, E793-06, E794-06. Details of the procedure as used in this invention are as follows: a TA Instruments DSC Q20 was used with nitrogen as carrier gas (99.998% purity, 50 mL/min). Temperature and heat flow calibrations were done using indium. Sample size was 5 to 7 mg. The weight was recorded ?0.01 mg. The heat cycles were: [0115] 1.sup.st heat cycle: 30.00? C. to 400.00? C. at 10.00? C./min, isothermal at 400.00? C. for 1 min; [0116] 1.sup.st cool cycle: 400.00? C. to 30.00? C. at 10.00? C./min, isothermal for 1 min; [0117] 2.sup.nd heat cycle: 30.00? C. to 400.00? C. at 10.00? C./min, isothermal at 400.00? C. for 1 min.

[0118] The melting temperature T.sub.m was determined as the peak temperature of the melting endotherm on the 2.sup.nd heat scan. The enthalpy of fusion was determined on the 2.sup.nd heat scan. The melting of the composition was taken as the area over a linear baseline drawn from 220? C. to a temperature above the last endotherm. When assessing the crystallinity of the film in the bonded structure (part), the heat of fusion was determined on the 1.sup.st heat scan.

[0119] The crystallization temperature T.sub.c was determined as the peak temperature of the crystallization exotherm on the 1st cool scan.

Determination of the Melt Viscosity

[0120] The melt viscosity was measured using a capillary rheometer according to ASTM D3835. Readings were taken after 10-minute (reported in Table 2) and 40-minute dwell time at 380 or 410? C. (as indicated) and a shear rate of 46.3 s.sup.?1 using a die with the following characteristics: diameter=1.016 mm, length=20.32 mm, cone angle=120?. The melt stability VR40 is measured by the ratio of the viscosity at 40 minutes over the viscosity at 10 minutes.

Determination of Tensile Properties

[0121] A 762 mm?762 mm?3.2 mm plaque was prepared from the polymer by compression molding of 30 g of polymer under the following conditions: preheat at T.sub.1, [0122] T.sub.1/20 minutes, 2000 kg-f [0123] T.sub.1/2 minutes, 2700 kg-f [0124] cool down to 30? C. over 40 minutes, 2000 kg-f

[0125] T.sub.1 values used for the polymers are indicated in the results table. The plaques were then annealed at 200? C. for 3 hours.

[0126] The 762 mm?762 mm?3.2 mm compression molded plaques were machined into Type V ASTM tensile specimens and these specimens of the various polymer compositions were subjected to tensile testing according to ASTM method D638 at 0.05 inch/minute (0.127 cm/min) room temperature (i.e. 23? C.) on 3 specimens. The average of the 3 specimens is presented with the standard deviation in brackets.

SYNTHESIS EXAMPLES

Comparative Example 1: PEKK with 60/40 T/I Ratio

[0127] In a 500 mL 4-neck reaction flask fitted with a stirrer, a N2 inlet tube, a Claisen adapter with a thermocouple plunging in the reaction medium, and a Dean-Stark trap with a condenser and a dry ice trap were introduced 112.50 g of diphenyl sulfone, 33.390 g of 1,3-BHBB, 6.372 g of 1,4-BHBB and 41.051 g of 1,4-DFDK. The flask content was evacuated under vacuum and then filled with high purity nitrogen (containing less than 10 ppm O.sub.2). The reaction mixture was then placed under a constant nitrogen purge (60 mL/min).

[0128] The reaction mixture was heated slowly to 270? C. At 270? C., 13.725 g of Na.sub.2CO.sub.3 and 0.086 g of K.sub.2CO.sub.3 was added via a powder dispenser to the reaction mixture over 60 minutes. At the end of the addition, the reaction mixture was heated to 320? C. at 1? C./minute. After 2 minutes at 320? C., 1.207 g of 1,4-DFDK were added to the reaction mixture while keeping a nitrogen purge on the reactor. After 5 minutes, 0.529 g of lithium chloride were added to the reaction mixture. 10 minutes later, another 0.503 g of 1,4-DFDK were added to the reactor and the reaction mixture was kept at temperature for 15 minutes. Another charge of 25 g of diphenyl sulfone was added to the reaction mixture, which was kept under agitation for 15 minutes. The reactor content was then poured from the reactor into a stainless steel pan and cooled. The solid was broken up and ground in an attrition mill through a 2 mm screen. Diphenyl sulfone and salts were extracted from the mixture with acetone and water at pH between 1 and 12. 0.67 g of NaH.sub.2PO.sub.4.Math.2H.sub.2O and 0.62 g of Na.sub.2HPO.sub.4 were dissolved in 1200 ml deionized water for the last wash. The powder was then removed from the reactor and dried at 120? C. under vacuum for 12 hours yielding 72 g of a yellow powder. The properties of the final polymer are detailed in Table 2.

Comparative Example 2: Preparation of PEEK-PEDEK 75/25 Copolymer

[0129] In a 500 mL 4-neck reaction flask fitted with a stirrer, a N.sub.2 inlet tube, a Claisen adapter with a thermocouple plunging in the reaction medium, and a Dean-Stark trap with a condenser and a dry ice trap were introduced 128.21 g of diphenyl sulfone, 20.297 g of hydroquinone, 11.411 g of 4,4-biphenol and 54.377 g of 4,4-difluorobenzophenone. The flask content was evacuated under vacuum and then filled with high purity nitrogen (containing less than 10 ppm O.sub.2). The reaction mixture was then placed under a constant nitrogen purge (60 mL/min).

[0130] The reaction mixture was heated slowly to 150? C. At 150? C., a mixture of 26.955 g of Na.sub.2CO.sub.3 and 0.169 g of K.sub.2CO.sub.3 was added via a powder dispenser to the reaction mixture over 30 minutes. At the end of the addition, the reaction mixture was heated to 320? C. at 1? C./minute. After 13 minutes at 320? C., 3.742 g of 4,4-difluorobenzophenone were added to the reaction mixture while keeping a nitrogen purge on the reactor. After 5 minutes, 1.039 g of lithium chloride were added to the reaction mixture. 10 minutes later, another 2.138 g of 4,4-difluorobenzophenone were added to the reactor and the reaction mixture was kept at temperature for 15 minutes.

[0131] The reactor content was then poured from the reactor into a SS pan and cooled. The solid was broken up and ground in an attrition mill through a 2 mm screen. Diphenyl sulfone and salts were extracted from the mixture with acetone and water at pH between 1 and 12. The powder was then removed from the reactor and dried at 120? C. under vacuum for 12 hours yielding 74 g of a white powder.

[0132] The melt viscosity measured by capillary rheology at 410? C., 46 s.sup.?1 was 0.28 KN-s/m.sup.2.

[0133] The properties of the final polymer are detailed in Table 2.

Comparative Example 3: Preparation of PEEK-PEmEK 70/30 Copolymer

[0134] In a 1000 mL 4-neck reaction flask fitted with a stirrer, a N.sub.2 inlet tube, a Claisen adapter with a thermocouple plunging in the reaction medium, and a Dean-Stark trap with a condenser and a dry ice trap were introduced 330.00 g of diphenyl sulfone, 37.949 g of hydroquinone, 16.234 g of resorcinol and 109.875 g of 4,4-difluorobenzophenone. The flask content was evacuated under vacuum and then filled with high purity nitrogen (containing less than 10 ppm O.sub.2). The reaction mixture was then placed under a constant nitrogen purge (60 mL/min).

[0135] The reaction mixture was heated slowly to 150? C. At 150? C., a mixture of 54.099 g of Na.sub.2CO.sub.3 and 0.170 g of K.sub.2CO.sub.3 was added via a powder dispenser to the reaction mixture over 30 minutes. At the end of the addition, the reaction mixture was heated to 300? C. at 1? C./minute. After 57 minutes at 300? C., 17.135 g of 4,4-difluorobenzophenone were added to the reaction mixture while keeping a nitrogen purge on the reactor. After 5 minutes, 2.081 g of lithium chloride were added to the reaction mixture. 10 minutes later, another 4.284 g of 4,4-difluorobenzophenone were added to the reactor and the reaction mixture was kept at temperature for 15 minutes.

[0136] The reactor content was then poured from the reactor into a SS pan and cooled. The solid was broken up and ground in an attrition mill through a 2 mm screen. Diphenyl sulfone and salts were extracted from the mixture with acetone and water at pH between 1 and 12. The powder was then removed from the reactor and dried at 100? C. under vacuum for 12 hours yielding 125 g of a light brown powder.

[0137] The melt viscosity measured by capillary rheolology at 410? C., 46 s.sup.?1 was 0.70 kN-s/m.sup.2. The properties of the final polymer are detailed in Table 2.

Example 4: Preparation of PEEK-PEoEK 80/20 Copolymer

[0138] In a 1000 mL 4-neck reaction flask fitted with a stirrer, a N.sub.2 inlet tube, a Claisen adapter with a thermocouple plunging in the reaction medium, and a Dean-Stark trap with a condenser and a dry ice trap were introduced 343.63 g of diphenyl sulfone, 61.852 g of hydroquinone, 15.426 g of pyrocatechol and 154.573 g of 4,4-difluorobenzophenone. The flask content was evacuated under vacuum and then filled with high purity nitrogen (containing less than 10 ppm O.sub.2). The reaction mixture was then placed under a constant nitrogen purge (60 mL/min).

[0139] The reaction mixture was heated slowly to 150? C. At 150? C., a mixture of 76.938 g of Na.sub.2CO.sub.3 and 0.484 g of K.sub.2CO.sub.3 was added via a powder dispenser to the reaction mixture over 30 minutes. At the end of the addition, the reaction mixture was heated to 320? C. at 1? C./minute. After 1 minute at 320? C., the reaction was terminated in 3 stages: 18.329 g of 4,4-difluorobenzophenone were added to the reaction mixture while keeping a nitrogen purge on the reactor. After 5 minutes, 2.338 g of lithium chloride were added to the reaction mixture. 10 minutes later, another 6.110 g of 4,4-difluorobenzophenone were added to the reactor and the reaction mixture was kept at temperature for 15 minutes.

[0140] The reactor content was then poured from the reactor into a SS pan and cooled. The solid was broken up and ground in an attrition mill through a 2 mm screen. Diphenyl sulfone and salts were extracted from the mixture with acetone and water at pH between 1 and 12. The powder was then dried at 120? C. under vacuum for 12 hours yielding 174 g of a white powder.

[0141] The melt viscosity measured by capillary rheology at 410? C., 46 s.sup.?1 was 1.50 KN-s/m.sup.2. The properties of the polymer are disclosed in Table 2 below.

Examples 5-7: Preparation of PEEK-PEoEK 75/25 and 70/30 Copolymers

[0142] The same procedure as Example 4 was followed but with the following amounts of reagents shown in Table 1. The properties of the resulting polymer are in Table 2.

TABLE-US-00001 TABLE 1 Reagents for the preparation of Examples 5-7 reagents Reagent Units Ex. 5 Ex. 6 Ex. 7 PEEK/PEoEK 75/25 75/25 70/30 Diphenyl sulfone g 340.54 343.63 343.63 Hydroquinone g 57.500 57.987 54.121 pyrocatechol g 19.109 19.282 23.139 4,4-difluorobenzophenone g 153.181 154.573 153.351 Na.sub.2CO.sub.3 g 76.245 76.938 76.938 K.sub.2CO.sub.3 g 0.479 0.484 0.484 Time at 320? C. minutes 33 16 73 4,4-difluorobenzophenone in first g 10.596 18.329 18.329 termination Lithium chloride in second g 2.941 2.388 2.388 termination 4,4-difluorobenzophenone in third g 6.055 343.63 6.110 termination Polymer weight g 185 188 188 Na.sub.2HPO.sub.4 g 1.86 1.86 1.86

[0143] Table 2 presents the properties of the samples prepared according to Examples 1-7

TABLE-US-00002 TABLE 2 Property Units CE1 CE2 CE3 E4 E5 E6 E7 PAEK unit PEKK PEDEK PEmEK PEoEK PEoEK PEoEK PEoEK PEEK/PAEK ratio 58/42 75/25 70/30 80/20 75/25 75/25 70/30 (mol/mol) MV (410? C., kN- 0.58 0.28 0.70 0.33 1.50 0.32 1.41 46 s.sup.?1) s/m.sup.2 Tg ? C. 158 151 135 143 145 143 144 Tm ? C. 303 307 293 309 294 292 283 Tc ? C. 214 255 221 261 226 200 195 Heat of fusion J/g 8 39 41 41 36 14 16 T.sub.1 molding ? C. 343 343 368 343 343 Tensile strength at MPa 93 79 @break N/A 97 N/A 95 95 yield or at break Tensile (Young) GPa 3.3 3.6 N/A 4.1 N/A 3.9 3.4 modulus

[0144] The data presented in Table 2 shows that PEEK-PEoEK copolymers are characterised by a generally low T.sub.m with the following advantages over the known PAEKs: [0145] increased crystallinity over PEKK for the same T.sub.m as shown by value of heat of fusion (CE1 vs E4); [0146] higher Tg than PEEK-PEmEK, hence higher continuous use temperature; [0147] improved mechanical properties over PEEK-PEDEK for the same T.sub.m (CE2 vs E4) [0148] the possibility to reach lower T.sub.m than with PEEK-PEDEK (T.sub.m<295? C.).

Example 10-11General Procedure for the Preparation of Bonding Films from the Polymers of Example 5 and CE 3

[0149] The polymer, in coarse powder form, was converted to pellets by melt compounding using a 26 mm Coperion? (model ZSK-26) co-rotating partially intermeshing twin screw extruder having an L/D ratio of 48:1. The powder was fed gravimetrically at a rate of 37 lbs/hr (16.8 kg/hr) into the feed hopper at barrel section 1 of the extruder. The extruder had 12 barrel sections with barrel sections 2 through 12, as well as the die, being heated with a temperature profile setting of 350? C. throughout. The melt temperature for the extrudate was measured by a handheld pyrometer as it exited the die.

[0150] The extrudate melt temperature was approximately 380? C. throughout the compounding run. The screw speed was set at 200 rpm, and, the resulting torque reading for the extruder was at approximately 50% throughout the production run. Vacuum venting with a vacuum level 26 in Hg was applied at barrel section 10 during compounding to strip off moisture and any possible residual volatiles from the compound. The extrudate from the run was stranded and cooled in a water trough and then pelletized into pellets approximately 2.7 mm in diameter and 3.0 mm in length.

[0151] The compounded pellets were processed into film having a nominal thickness of 140 microns and a width of 8.5 to 9 cm using melt extrusion on a single screw extruder. An OCS (Optical Control Systems, GmbH) extruder was used for this purpose. The extruder had a single stage non-vented screw with a diameter of 20 mm and an L/D ratio of 30. It was equipped with a film die 125 mm wide having a 0.5 mm gap thickness. The extruder barrel had four heated sections which were operated from rear to front at temperature settings of approximately: 335, 360, 360 and 370? C., respectively. The film die was set at a temperature of 390? C. Before extrusion into film, the pellets were dried overnight (about 16 hours) in a desiccated air convection oven set at 150? C. The blend was extruded using a screw speed of 28 rpm and a throughput rate of about 4 lb/hr (1.8 kg/hr). The film was formed and drawn down on two chill rolls, set at 140 and 145? C., for the first (top) and second (bottom) roll, respectively.

Example 11: Preparation of Assemblies and Fracture Toughness Tests

[0152] Fracture toughness (G1c) laminates (305 mm?305 mm size) whereby the layer in the crack plane is the fusion bonding film that is fused to the surface of the fiber reinforced composite substrate were made as follows. APC (polymer per example 8)/AS4D unitape with a nominal fiber areal weight=145 gsm and resin content of 34 wt. % was cut and stacked to make a 16 ply quasi-isotropic orientation (+45?/0?/?45?/90? 02 s lay-up. On top of that lay-up stack, 1 ply of style 108 glass fabric was placed covering the entire surface followed by placing a 280 mm?305 mm?0.125 mm film of Example 10 with three of the edges aligned with the edges of the lay-up. The other edge had a 305 mm?25 mm?0.05 mm thick release coated Kapton film that was the crack starter once the panel was consolidated. The remainder of the lay-up was to reverse the order of the material placed starting with style 108 fiberglass fabric followed by 16 ply quasi-isotropic.

[0153] The lay-up was then placed on a flat steel tool and vacuum bagged (710-730 mm Hg vacuum) to be processed in a high temperature autoclave. The autoclave cycle was a straight temperature ramp to 375? C. at which point 6.7 bars of pressure was applied and held for 15 minutes before cooling the lay-up down while under 6.7 bar (670 kPa) pressure and 711 mm Hg. The pressure was released at 93? C. and cooled down to room temperature before removing from the autoclave. The resulting panels were measured for thickness and then machined into 1?12 (2.5 cm?30.5 cm) test coupons to conduct G1c fracture toughness measurements.

TABLE-US-00003 TABLE 3 G1c results at RTA Example Lay-up G1c (J/m.sup.2) Ex 5 [45/90/?45/0]2s/108glass/PEEK- 1245 PEoEK/108 glass/[45/90/?45/0]2s CE3 [45/90/?45/0]2s/108glass/PEEK- 355 PEmEK/108 glass/[45/90/?45/0]2s

[0154] The data shows that the use of a bonding film according to the invention (Example 5) provided an improved binding of laminates as demonstrated by a high value fracture toughness strength.