Coating process based on a PAEK having a low melting temperature

Abstract

This present invention pertains to a method for preparing a coating layer on a metallic surface (S) of a component (CO), said component (CO) comprising metallic parts bonded by an adhesive composition (Adh), wherein the method comprises the following steps: - step 1): applying a coating composition (CC) comprising as least one poly(aryl ether ketone) [noted PAEK1] having a melting temperature (Tm) of at most 330°C, preferably at most 320 °C, more preferably at most 315 °C, most preferably at most 310 °C, onto the metallic surface (S) to be coated; - step 2): baking the applied coating composition (CC) whereby the metallic surface (S) is coated with a coating layer comprising the poly(aryl ether ketone).

Description

SSPU 2024 / 0351Coating process based on a PAEK having a low melting temperature[Reference to related Applications]This application claims priority from US provisional application Nr. 63 / 703804 filed on October 4, 2024 and from European patent application Nr. 24209501.6 filed on October 29, 2024, the whole content of these applications being incorporated herein by reference for all purposes.[Technical field]

[0001] This present invention pertains to a coating process based on a PAEK having a low melting temperature (Tm).[Background art]

[0002] In electric motors (e-motors), the rotor and stator cores are generally made from motor laminations. These laminations are thin metal sheets that are bonded, welded, or stacked together to create multiple robust layers. Using individual metal sheets instead of a single solid piece helps minimize eddy current losses. Typically, these cores are composed of thousands, or even hundreds of thousands, of steel laminations.

[0003] US2023 / 0119661 and US11,715,999 describe a standard process for manufacturing a lamination stack used in electric machines.

[0004] To date, most e-motor stators and rotors have used films or injection-molded components as slot liners and insulation. Traditionally, these films have been made from aramid papers or laminates, but thermoplastic films are becoming increasingly popular. Some stators and rotors have been coated with epoxy materials that cure at lower baking temperatures; however, these coatings do not offer the same electrical insulation, weight reduction, or thermal resistance as certain polymeric materials.

[0005] WO 2023 / 152236 discloses slot liners made of a composition comprising a polyarylether ketone (PAEK).

[0006] WO 2006 / 117512 discloses coatings made of PEEK.

[0007] WO 2020 / 254101 discloses a polymer-metal junction comprising a PEEK-PEoEK copolymer.SSPU 2024 / 0352

[0008] WO 2021 / 008983 discloses a powder-coating of a fiber with a PEEK-PEoEK copolymer.

[0009] WO 2021 / 001132 discloses electrostatic powder coating with a PEEK-PEoEK copolymer.

[0010] US 2009 / 0280263 discloses a powder of PEEK that is used for coating.[Technical problem to be solved]

[0011] E-motor’s rotor and stator cores are generally made from motor laminations which are thin metal sheets that are bonded, welded, or stacked together. In various methods for producing laminated rotors or stators, an adhesive is used to bond the laminated stacks together. This adhesive is most commonly formulated from methacrylate or epoxy resins.

[0012] There is a need for a technique that enables the application of a polymer-based, ready- to-use coating onto the metallic surface of such a component, that is a rotor or stator lamination. To ensure proper adhesion and achieve a suitable coating, the component must be heated. The method should enable the formation of the coating on the metal surface without causing degradation of the adhesive material.

[0013] The invention disclosed herein aims at solving this technical problem.[Brief disclosure of the invention]

[0014] The invention is set out in the appended set of claims.

[0015] The subject-matters claimed and described herein are now defined in more detail below.[Figures]

[0016] Fig. 1 / 1 illustrates the T-peel or 90°-peel adhesion test.[Definition]

[0017] In the present application, wt% and mol% designate respectively % by weight and % by mole.

[0018] The proportion of recurring units in a polymer are expressed in mol% and relative to the total amount of recurring units in said polymer.SSPU 2024 / 0353

[0019] The proportions of the component(s) of the coating composition (CC) are expressed in wt% and relative to the total weight of the coating composition (CC).

[0020] In all numerical ranges (also in those without upper or lower end points), unless otherwise indicated, the end-points are included.

[0021] In the present application, the indeterminate article “a” in an expression like “a polymer”, is intended to mean “one or more”, or “at least one” unless indicated otherwise.

[0022] In the present application, unless otherwise indicated, any specific embodiment or technical feature relating to a subject-matter is applicable to and interchangeable with another embodiment or technical feature also relating to the same subject-matter and disclosed elsewhere in the application. In particular, it is highlighted that all details and embodiments disclosed for the method of the invention are also applicable for the uses (see 3rdand 4thaspects).

[0023] A “poly(aryl ether ketone) ” (herein abbreviated PAEK) denotes a polymer, the units of which comply with formula -Q-Ar- where Ar is an arylene group selected in the group consisting of phenylene, biphenylene or napthylene group and Q is -O- or -C(=O)- where each Q of a recurring unit is bound to Ar of another subunit. For instance, PEEK is a PAEK as the recurring units of PEEK are of formula:are formed of the following subunits -O-Ar- and -C(=O)-Ar where Ar = 1,4-phenylene.

[0024] A PAEK is typically prepared by polycondensation. In the context of the invention, the polycondensation is generally a nucleophilic polycondensation (except for PEKK for which two polycondensation routes are available - see below) which comprises the reaction of monomers bearing two fluoro atoms with monomers bearing two hydroxy groups in an aprotic solvent in the presence of a base selected in the group consisting of Na2CC>3, K2CO3 and combination Na2CO3+K2CO3.[Disclosure of the invention]

[0025] As a first aspect, the invention relates to a method for preparing a coating layer on a metallic surface (S) of a component (CO), said component (CO) comprising metallicSSPU 2024 / 0354 parts bonded by an adhesive composition (Adh), wherein the method comprises the following steps: step 1): applying a coating composition (CC) as defined herein which comprises at least one PAEK [PAEK1] having a melting temperature (Tm) of at most 330°C, preferably at most 320 °C, more preferably at most 315 °C, most preferably at most 310°C, onto the metallic surface (S) to be coated; step 2): baking the applied coating composition (CC) whereby the metallic surface (S) is coated with a coating layer comprising the PAEK.

[0026] Component (CO) is typically a rotor or a stator of an electrical machine.

[0027] As a second aspect, the invention relates to a method for preparing a coating layer on a metallic surface (S) of a laminated rotor or stator comprising lamination stacks bonded by an adhesive composition (Adh), wherein the method comprises the following steps: step 1): applying a coating composition (CC) as defined herein comprising as least one PAEK [PAEK1] having a melting temperature (Tm) of at most 330°C, preferably at most 320 °C, more preferably at most 315 °C, most preferably at most 310 °C, the metallic surface (S) to be coated; step 2): baking the applied coating composition (CC) whereby the metallic surface (S) is coated with a coating layer comprising the PAEK.

[0028] As a third aspect, the invention also relates to the use of a PAEK [PAEK1] having a melting temperature (Tm) of at most 330°C, preferably at most 320 °C, more preferably at most 315 °C, most preferably at most 310 °C, for the preparation of a polymer coating on the metallic surface (S) of a laminated rotor or stator comprising lamination stacks, notably bonded by an adhesive composition (Adh).

[0029] As a fourth aspect, the invention also relates to the use of a coating composition (CC) as defined herein for the preparation of a polymer coating on the metallic surface (S) of a laminated rotor or stator comprising lamination stacks, notably bonded by an adhesive composition (Adh).

[0030] In the present application, this PAEK will be referred to also as PAEK1 to differentiate from any other optional PAEK that may be present also in the coating composition (CC) (see below).SSPU 2024 / 0355

[0031] The adhesive composition (Adh) is preferably a thermally sensitive adhesive composition. The expression “thermally sensitive” is used herein to refer to an adhesive composition which forms a bond when exposed to heat. In the specific situation of the invention the adhesive composition bonds together the adjacent laminae in the lamination stack by the application of heat.

[0032] The adhesive composition (Adh) is typically based on a thermoset. It is typically an epoxy-based adhesive composition. Examples of adhesive compositions are provided in US 2023 / 0119661. An epoxy-based adhesive composition used to bond the metallic parts typically comprises: i) an epoxy resin; ii) at least one curing agent; iii) optionally at least an accelerator.

[0033] The epoxy resin can be aliphatic, cycloaliphatic or aromatic. Examples of aliphatic epoxy resins can be butanediol diglycidyl ether, hexanediol diglycidyl ether, dimethylpentane dioxide, butadiene dioxide, and diethylene glycol diglycidyl ether.

[0034] Cycloaliphatic epoxy resins include, for example, 3 -cyclohex enylmethyl-3- cyclohexylcarboxylate diepoxide, 3,4-epoxycyclohexylalkyl-3 ',4'-epoxycyclohexane carboxylate, 3, 4-epoxy-6-methylcy cl ohexylmethyl-3',4'-epoxy-o-methyl cyclohexane carboxylate, vinylcyclohexane dioxide, bis(3,4-epoxycyclohexylmethyl)adipate, dicyclopentadiene dioxide, and l,2-epoxy-6-(2,3-epoxypropoxy)hexahydro-4,7- methanoindane. Aromatic epoxy resins include, for example, bisphenol A epoxide resins, bisphenol F epoxide resins, phenol novolac epoxide resins, cresol novolac epoxide resins, biphenyl epoxide resins, biphenol epoxide resins, 4,4'-biphenoline epoxide resins, divinyl benzene dioxide, 2-glycidyl phenyl glycidyl ether, and tetraglycidyl methylene dianiline.

[0035] The curing agent is a substance or a mixture of substances which preferably enter into curing reactions with the epoxy resin of the adhesive at temperatures in the range of from 80°C to 200°C. The curing agent can contain dicyandiamides, aziridine derivatives, triazine derivatives, imidazolines, imidazoles, o-tolyl biguanide, cyclic amidines, organic hexafluoroantimonate or hexafluorophosphate compounds or BF3 amine complexes.

[0036] The adhesive typically also contains an accelerator. Suitable accelerators are urea derivatives. The urea derivative can be an N,N-dimethylurea or an N,N'-dimethylurea orSSPU 2024 / 0356 a bifunctional urea derivative, preferably with two urea groups as functional groups, very particularly preferably a 4,4'-methylene-bis-(phenyldimethylurea), or a mixture of a plurality of the above.

[0037] Step 1)

[0038] In step 1), the coating composition (CC) as defined herein is applied on the metallic surface (S). Depending on the application, the coating composition (CC) may be applied only on a portion of said surface (S).

[0039] Surface (S) to be coated may have been pretreated prior to applying the coating composition (CC), notably with a treatment selected from flame treatment, mechanical abrasion, chemical treatment and combination thereof. This pretreatment is designed to improve the adhesion of the coating on the metallic surface. An example of pretreatment of surface (S) with the combination of a chemical treatment and a mechanical abrasion is provided in the Experimental Section.

[0040] The coating composition (CC) can be applied in different ways as detailed below.

[0041] Embodiment (El)

[0042] According to an embodiment (El), the coating composition (CC) in the powder form is applied onto the metallic surface resulting in the powder adhering to the metallic surface (S) or to a portion of the metallic substrate (S).

[0043] The coating composition (CC) may be applied by a fluidized-bed process wherein the metallic surface is dipped into a fluidized bed of the coating composition (CC).

[0044] The coating composition (CC) may also be applied by spraying the coating composition (CC) in the form of a powder form.

[0045] According to this embodiment (El), the metallic surface (S) is preheated, so that before step 2), the powder fuses on contact with the hot surface.

[0046] Embodiment (E2)

[0047] According to an embodiment (E2), the coating composition (CC) is applied in the form of a slurry on the metallic surface or to a portion of the metallic substrate.

[0048] Step 2)

[0049] In step 2), the coating composition (CC) is baked. The temperature Tstep2 at which step 2) is performed should be sufficient to melt the particles of PAEK1 and more generally to melt the polymeric component(s) of the coating composition. Tstep2 is typically higherSSPU 2024 / 0357 than the melting temperature Tm of PAEK1 (Tstep2 > Tm). Tstep2 is typically higher than Tm + 10°C, preferably Tm + 20°C. In case the coating composition (CC) comprises more than one PAEK, the Tm to be taken into account is the highest melting temperature of the PAEKs present in the coating composition (CC).

[0050] After step 2), the thickness of the coating comprising PAEK1 on the metallic surface (S) is typically between 10.0 to 700.0 pm, more particularly between 50.0 and 400.0 pm. The thickness may more particularly be between 70.0 and 350.0 pm.

[0051] The coating comprising PAEK1 on the metallic surface (S) provides an electrical insulation.

[0052] The method of the invention may comprise an additional step 3) under which the coating layer is further heated to increase the crystallinity level of the coating layer. The temperature at which step 3) is performed is at least 150°C. This temperature is typically between 150°C and 250°C.

[0053] The polymer coating layer preferably exhibits a level of crystallinity 1 of at least 10.0%. The level of crystallinity is determined by the following equation:1 = heat of fusion of the coating layer (J / g) / 130 (J / g) x 100 where the heat of fusion of the coating layer is measured by DSC on the 1stheat scan according to ASTM D3418-03, more particularly ASTM D3418-03, E1356-03, E793- 06, E794-06 with a cooling and heating rate of 10 °C / min. Level of crystallinity 1 is typically at most 50.0%.

[0054] Coating composition (CC)

[0055] Details about the coating composition (CC) which is used in the present invention are now given.

[0056] The coating composition (CC) comprises at least 50.0 wt% (> 50.0 wt%) of a semicrystalline polymer PAEK [PAEK1] and exhibiting a melting temperature (Tm) of at most 330°C, preferably at most 320 °C, more preferably at most 315 °C, most preferably 310 °C, this proportion being relative to the total weight of the coating composition (CC).

[0057] Semi-crystalline polymer PAEK [PAEK1] is the major component of the coating composition (CC).

[0058] The coating composition (CC) more particularly comprises, consists essentially or consists of:SSPU 2024 / 0358 at least 50.0 wt% (> 50.0 wt%) of at least one semi-crystalline polymer PAEK [PAEK1] as defined herein, this proportion being relative to the total weight of the coating composition (CC); optionally at least one additional polymer (P) selected in the group consisting of PAEKs different from PAEK1, polysulfones (PSU), polyphenylenesulfones (PPSU), polyetherimide (PEI) and combinations thereof; optionally at least one plastic additive (Add), notably selected in the group consisting of colorants (e.g. dyes and / or pigments), impact modifiers, ultraviolet light stabilizer, heat stabilizers, antioxidants, internal lubricants and / or external lubricants, flame retardants, anti-static agents, anti-blocking agents and combinations thereof; optionally at least one flow agent.

[0059] The proportion of semi -crystalline PAEK(s) (PAEK1) in the coating composition (CC) is at least 50.0 wt% (> 50.0 wt%), this proportion being relative to the total weight of the coating composition (CC). This proportion is preferably at least 60.0 wt%, preferably at least 65.0 wt%, preferably at least 70.0 wt%, preferably at least 75.0 wt%, preferably at least 80.0 wt%, preferably at least 85.0 wt%, preferably at least 90.0 wt%, preferably at least 95.0 wt%, preferably at least 99.0 wt%.

[0060] The proportion of the flow agent(s) (if any) is typically between 0.05 wt% and 5.0 wt%.

[0061] The flow agent is typically selected in the group consisting of silica, alumina, titanium dioxide, talc, mica, kaolin, attapulgite, calcium silicate, alumina and magnesium silicate and combination thereof.

[0062] The flow agent is more particularly selected in the group consisting of hydrophilic, hydrophobic silica and combination thereof.

[0063] The coating composition (CC) may comprise: at least one additional polymer (P) selected in the group consisting of PAEKs different from PAEK1, polysulfones (PSU), polyphenylenesulfones (PPSU), polyetherimide (PEI) and combinations thereof; and / or at least one plastic additive (Add), notably selected in the group consisting of colorants (e.g. dyes and / or pigments), impact modifiers, ultraviolet light stabilizer,SSPU 2024 / 0359 heat stabilizers, antioxidants, internal lubricants and / or external lubricants, flame retardants, anti-static agents, anti-blocking agents and combinations thereof.

[0064] According to an embodiment, polymer(s) (P) and additive(s) (Add) form a homogeneous mixture. This homogeneous mixture can be prepared by melt, slurry or powder mixing said components

[0065] According to a preferred embodiment, the coating composition (CC) comprises, consists essentially or consists of: at least 95.0 wt% (> 95.0 wt%) of a semi-crystalline polymer PAEK [PAEK1] as defined herein; optionally at least one flow agent, the proportion of which being notably between 0.05 wt% and 5.0 wt%; these proportions being relative to the total weight of the coating composition (CC).

[0066] Melting temperature (Tm) of the PAEK [PAEK1] is determined by differential scanning calorimeter (DSC) on the 2ndheat scan according to ASTM D3418-03, more particularly ASTM D3418-03, E1356-03, E793-06, E794-06 with a cooling and heating rate of 10 °C / min. Tm is typically between 270°C and 330°C. The values of Tm mentioned herein correspond to the values of the main peak that is the peak temperature of the highest melting endotherm.

[0067] The melt viscosity (MV) of the PAEK [PAEK1] is typically between 700 and 1400 Pa s, MV being measured with a capillary rheometer according to ASTM D3835 with the following conditions: 100 s’1; 360 °C.

[0068] The heat of fusion (Hm) of the PAEK [PAEK1] is preferably at least 5.0 J / g, Hm being determined by differential scanning calorimeter (DSC) on the 2ndheat scan according to ASTM D3418-03 with a cooling and heating rate of 10 °C / min. Hm is more particularly between 5.0 and 50.0 J / g.

[0069] The glass transition temperature (Tg) of the PAEK [PAEK1] is typically between 130°C and 170 °C, Tg being determined by differential scanning calorimeter (DSC) on the 2ndheat scan according to ASTM D3418-03 with a cooling and heating rate of 10 °C / min.

[0070] According to an embodiment, the coating composition (CC) is in form of a slurry comprising the components of the coating composition (CC) in the form of particlesSSPU 2024 / 03510 dispersed in a liquid medium (LM). The liquid medium is typically a water-based liquid medium.

[0071] Method of preparation of the coating composition (CO

[0072] The coating composition (CC) in the powder form is prepared by a process comprising the following steps:- i): a composition (c) comprising the PAEK is ground at a temperature comprised between -25°C and 150°C, preferably between 0°C and 80°C; and- ii): after the grinding step i), one or more of the component(s) of the coating composition (CC) other than those already present in composition (c) are incorporated in the powder obtained at the end of step i); and- iii): step i) and / or step ii) is / are optionally reiterated;- iv): the resulting powder is optionally subject to one or more sieving or classifying step.

[0073] After step iv), the resulting powder may be heated at a temperature of at least 150°C.The duration of this heating step may be at least 5.0 hours.

[0074] Grinding step i) is performed with a grinding mill, notably selected in the group consisting of rotor mills, jet mills, notably fluidized jet mill, impact mills, wet-grinding mills and pin mills.

[0075] The grinding mill may more particularly be a rotor mill as illustrated in the Experimental Section. The functional principle of the rotor mill is the following: the reduction of size is achieved by impact and shear effects. The feed material passes from a hopper into the center of the grinding chamber where it is crushed between the rotor, sieve and grinding inserts. As soon as the material is smaller than the aperture size of the sieve it enters the collecting receptacle through the gravity outlet. The airborne fine fraction is separated off by a downstream filter system. The optionally available cyclone separator ensures cooling of the sample material and the cutting tools and improves the discharge of the sample from the grinding chamber.

[0076] Composition (c) used in step i) comprises a PAEK. According to an embodiment, composition (c) consists essentially of or consists of a PAEK. According to another embodiment, composition (c) comprises, consists essentially of or consists of a PAEK and one or more of the other components of the coating composition (CC).SSPU 2024 / 03511

[0077] For step i), the conditions of grinding disclosed in the experimental section of US 11,691,315, US 2009 / 0280263, US 5,247,052 or EP 3994200 can be used and adapted if necessary. The conditions provided in the Experimental Section can be used.

[0078] The coating composition (CC) in the slurry form is prepared by dispersing the coating composition (CC) in the powder form in a liquid medium. A dispersing agent may be added to help disperse the particles into the liquid medium.

[0079] According to an embodiment, the coating composition (CC) is in the powder form and exhibits a Dv50 between 10.0 and 200.0 pm, preferably between 35.0 and 60.0 pm. The coating composition (CC) in the powder form more particularly exhibits the following parameters of distribution: a DvlO between 5.0 and 100.0 pm, preferably between 7.0 and 50.0 pm; a Dv50 between 10.0 and 200.0 pm, preferably between 20.0 and 80.0 pm; a Dv90 between 50.0 and 300.0 pm, preferably between 40.0 and 200.0 pm. or the following ones: a DvlO between 7.0 and 50.0 pm; a Dv50 between 20.0 and 80.0 pm; a Dv90 between 40.0 and 200.0 pm.

[0080] According to an embodiment, the coating composition (CC) is in the slurry form and exhibits a Dv50 between 1.0 and 100.0 pm, preferably between 2.0 and 50.0 pm. The coating composition (CC) in the slurry form more particularly exhibits the following parameters of distribution: a Dv50 between 1.0 and 100.0 pm, preferably between 2.0 and 50.0 pm; a Dv90 between 10.0 and 200.0 pm, preferably between 10.0 and 70.0 pm. or the following ones: a Dv50 between 2.0 and 50.0 pm; a Dv90 between 10.0 and 70.0 pm.

[0081] According to an embodiment, all parameters of the distribution disclosed herein for the coating composition (CC) apply also for the distribution of sizes of the PAEK [PAEK1],

[0082] These parameters DvlO, Dv50 and Dv90 have the usual meanings used in statistics. DvX (X= 10, 50 or 90) is determined from a distribution in volume obtained by laserSSPU 2024 / 03512 scattering, the particles being dispersed in isopropanol. Dv50 is also referred to as the median.

[0083] About PAEK [PAEK1]

[0084] The PAEK [PAEK1] is a semi -crystalline polymer that provides a resistant coating on the metallic surface.

[0085] PAEK [PAEK1] is preferably selected in the group consisting of PEEK-PEoEK, PEEK- PEDEK, PEEK-PEmEK, PEKK and combination thereof.

[0086] Details and embodiments about these specific PAEKs are provided below.

[0087] PEEK-PEoEK

[0088] According to an embodiment, PAEK1 is a PEEK-PEoEK as defined herein.

[0089] A PEEK-PEoEK is a polymer comprising at least 90.0 mol%, preferably at least 95.0 mol%, preferably at least 99.0 mol% of the two following recurring units:The recurring units are bound together by O.

[0090] The PEEK-PEoEK preferably exhibits a molar ratio RPEEK / RPEOEK between 65 / 35 and 85 / 15, preferably between 70 / 30 and 80 / 20.

[0091] The Tm of PEEK-PEoEK is preferably between 290 and 320°C.

[0092] The PEEK-PEoEK is prepared by a nucleophilic polycondensation process of the following monomers: hydroquinone, 4,4-difluorobenzophenone and pyrocatechol.

[0093] According to an embodiment, the PEEK-PEoEK possesses a microstructure such that its FT-IR spectrum, when recorded between 600 and 1000 cm’1in ATR mode is such that the following inequalities are satisfied:—1(i)700 cm— < 0.99, wherein i4700 cm-i is the of absorbance at 700 cm’1andAO4 cm-1i4704 cm-i is the absorbance at 704 cm’1;SSPU 2024 / 03513 > 0.61, wherein i4816 cm-i is the of absorbance at 816 cm'1and i4835 cm-iis the absorbance at 835 cm'1;(iii)623 cm— < 1.60, wherein i4623 cm-i is the of absorbance at 623 cm'1and i4557 cm-i A557 cm- 1is the absorbance at 557 cm'1;(iv)928 cm— < 1.09, wherein i4928 cm-i is the of absorbance at 928 cm'1and i4924 cm-i A924 cm- 1is the absorbance at 924 cm'1.

[0094] This PEEK-PEoEK preferably exhibits a calcium (Ca) content of less than 5.0 ppm, this content being measured by ICP-OES.

[0095] This PEEK-PEoEK is obtained by the method disclosed in WO 2020 / 254097.

[0096] PEEK-PEDEK

[0097] According to an embodiment, PAEK1 is a PEEK-PEDEK as defined herein.

[0098] A PEEK-PEDEK is a polymer comprising at least 90.0 mol%, preferably at least 95.0 mol%, preferably at least 99.0 mol% of the two following recurring units:These recurring units are bound together by O. PEEK-PEDEK copolymer is prepared by nucleophilic polycondensation of the following monomers: hydroquinone, 4,4- difluorobenzophenone and 4,4’ -dihydroxybiphenyl (formula:

[0099] The PEEK-PEDEK preferably exhibits a molar ratio RPEEK / RPEDEK between 65 / 35 and 85 / 15, preferably between 70 / 30 and 80 / 20.

[0100] The Tm of PEEK-PEDEK is preferably between 295 and 320°C.

[0101] PEEK-PEmEK

[0102] According to an embodiment, PAEK1 is a PEEK-PEmEK as defined herein.SSPU 2024 / 03514

[0103] A PEEK-PEmEK is a polymer comprising at least 90.0 mol%, preferably at least 95.0 mol%, preferably at least 99.0 mol% of the following recurring units:These recurring units are bound together by O. PEEK-PEmEK copolymer is prepared by nucleophilic polycondensation of the following monomers: hydroquinone, 4,4- difluorobenzophenone and resorcinol.

[0104] The PEEK-PEmEK preferably exhibits a molar ratio RpEEx / RpEmEK between 65 / 35 and 90 / 10, preferably between 70 / 30 and 85 / 15.

[0105] PEKK

[0106] According to an embodiment, PAEK1 is a PEKK as defined herein.

[0107] A PEKK is a polymer comprising at least 90.0 mol%, preferably at least 95.0 mol%, preferably at least 99.0 mol% of the following recurring units:These recurring units are bound together by O.SSPU 2024 / 035

[0108] A PEKK can be prepared by nucleophilic polycondensation of a reaction mixture comprising the monomers having the following formulae and a base selected in the group consisting of Na2COs, K2CO3 and a combination thereof:where X is either F(bis(fluorobenzoyl) benzene monomers) or OH (bis(hydroxybenzoyl) benzene monomers) with the condition that the molar ratio bis(fluorobenzoyl) benzene monomer(s) / bis(hydroxybenzoyl) benzene monomer(s) is substantially close to 1.0 (this polycondensation will be referred to as the “nucleophilic route ’"). The molar ratio bis(fluorobenzoyl) benzene monomer(s) / bis(hydroxybenzoyl) benzene monomer(s) is typically from about 0.9: 1 to about 1 :0.9, more preferably 0.95: 1 to 1 :0.95, most preferably from about 0.97: 1 to about 1 :0.97, and most preferably between 0.97: 1 and 1.00: 1. An example of process of preparation following this nucleophilic route is described in e.g. EP 3559084 Bl.

[0109] A PEKK can also be prepared by polycondensation of a reaction mixture comprising diphenyl ether, terephthaloyl acyl chloride, isophthaloyl acyl chloride and a Lewis acid (this polycondensation will be referred to as the “electrophilic route ”). An example of process of preparation following this electrophilic route is described in e.g. WO 2014 / 013202.

[0110] The PEKK preferably exhibits a molar ratio RpEKKp / RpEEKm between 55 / 45 and 68 / 32, preferably between 57 / 43 and 65 / 35.

[0111] The Tm of PEKK is preferably between 295 and 310°C.

[0112] PAEK1, notably the PEKK polymer, preferably exhibits a Td(l%) of at least 490.0°C, preferably at least 495.0°C, preferably at least 500.0°C, preferably at least 505.0°C, Td(l%) representing the temperature at 1% weight loss and being measured by thermal gravimetric analysis ("TGA") according to ASTM D3850, with a heating under nitrogen from 30°C to 800°C using a heating rate of 10°C / min. The higher Td(l%), the lower the amount of volatiles from the PAEK and consequently the better for the quality of the coating.

[0113] Phosphorous contentSSPU 2024 / 03516

[0114] PAEK1 preferably exhibits a phosphorous content (P content) of at least 30.0 ppm, more preferably at least 40.0 ppm, most preferably at least 60.0 ppm. This phosphorous content is preferably between 30.0 and 1000.0 ppm. The P content is expressed in ppm and relative to the weight of PAEK1. For clarity, 1 ppm = 1 mg / kg. The P content is typically measured by Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES), notably according to the protocol present in the Experimental Section.

[0115] According to an embodiment, the coating composition (CC) exhibits a phosphorous content of at least 15.0 ppm, more preferably at least 20.0 ppm, most preferably at least 30.0 ppm. This phosphorous content is preferably between 15.0 and 500.0 ppm.

[0116] According to an embodiment, to obtain the above-defined P content, the PAEK1 is submitted to washing with an aqueous solution comprising an inorganic phosphorous salt selected in the group of dihydrogen phosphates, hydrogen phosphates and combination thereof. The inorganic phosphorous is more particularly selected in the group consisting of Na2HPO4, NaEEPCU and combination thereof.

[0117] According to an embodiment, the source of P at stake here consists of an inorganic phosphorous salt as defined herein.[Experimental section]

[0118] Preparation of a coating composition (CC)

[0119] Raw Materials used: hydroquinone, photo grade, was procured from Eastman, USA. It contains 0.38% moisture, which amount was used to adapt the charge weights. All weights indicated include moisture; pyrocatechol, flakes, was procured from Solvay USA. Its purity was measured at 99.85% by GC. It contained 680 ppm moisture, which amount was used to adapt the charge weights. All weights indicated include moisture;4,4’-difluorobenzophenone, polymer grade (99.8%+), was procured from Malwa, India; diphenyl sulfone (polymer grade) was procured from Proviron (99.8% pure); sodium carbonate, light soda ash, was procured from Solvay S.A., France; potassium carbonate with a d90 < 45 pm was procured from Armand products; lithium chloride (anhydrous grade) was procured from Acros;SSPU 2024 / 03517 hydrophilic silica (flow aid) Cabosil M5 was procured from Cabot.

[0120] Determination of the P content

[0121] ICP-OES analysis is performed using an inductively-coupled plasma emission calibrated spectrometer Perkin-Elmer Optima 8300 dual view.

[0122] The P content in the sample is calculated with the following equation:A = (B x C) / (D) where:- A = concentration of element in the sample in mg / kg (ppm);- B = element in the solution analyzed by ICP-OES in mg / L;- C = volume of the solution analyzed by ICP-OES in mL;- D = sample weight in grams.

[0123] Determination of Particle Size Distribution (Dv90., Dv50., DylO)

[0124] The PSD (volume distribution) was determined by an average of 3 runs using laser scattering Microtrac S3500 analyzer in wet mode (128 channels, between 0.0215 and 1408 pm). The solvent was isopropanol with a refractive index of 1.38 and the particles were assumed to have a refractive index of 1.59. The ultrasonic mode was enabled (25 W / 60 seconds) and the flow was set at 55%.

[0125] Preparation of PEEK-PEoEK [PAEK1]: in a 1000 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 343.63 g of diphenyl sulfone, 58.087 g of hydroquinone, 19.290 g of pyrocatechol and 154.789 g of 4,4’ -difluorobenzophenone. RPEEK / RPEOEK is therefore a ratio of 3. The flask content was evacuated under vacuum and then filled with high purity nitrogen (containing less than 10 ppm O2). The reaction mixture was then placed under a constant nitrogen purge (60 mL / min). The reaction mixture was heated slowly to 150 °C. At 150 °C, a mixture of 77.077 g of ISfeCCL and 0.484 g of K2CO3 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 l°C / minute. After 16 minutes 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, 2.388 g of lithium chloride were added to the reaction mixture. 10 minutes later, another 6.110SSPU 2024 / 03518 g of 4,4’ -difluorobenzophenone were added to the reactor and the reaction mixture was kept at temperature for 15 minutes. 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 by extracting successively with acetone and water at room temperature. 0.67 g of NaPfcPCU 2H2O and 0.62 g of Na2HPO4 were dissolved in 1200 mL DI water for the last wash. The powder was then dried at 120 °C under vacuum for 12 hours yielding 189 g of a white powder. The reaction was repeated to accumulate more than 1 kg of the polymer material.

[0126] Preparation of a coating composition (CO in the form of a fine powder mix: 1 kg of polymer material was tumbled with 0.3 wt% silica and the mixture was slowly fed to the feed port of a Retsch SR200 rotor mill, fitted with a 0.5 mm opening Coni dur screen mounted in the reverse flow position and standard 6-blade rotor with a speed of 10,000 rpm. The feed rate was adjusted so that the outlet pipe of the grinder was cold to the touch (T max 30-40 °C). The material was re-fed to the Retsch SR200 with a 0.25 mmm then through a 0.08 mm screen, also in the reverse flow position with a standard 6-blade rotor at 10,000 rpm.

[0127] Once all the material had been ground through the 0.08 mm grinding screen, it was sieved through a 106 pm screen. The final ground powder had DvlO, Dv50 and Dv90 particle size values as follows:- DvlO: 21 pm;- Dv50: 50 pm;- Dv90: 97 pm.

[0128] The powder was then heat treated in an oven at 200 °C for 16 hours.

[0129] Example 1

[0130] Plaque Preparation:

[0131] The metal substrate used was aluminum and the plates used measured 0.025 in x 4 in x 6 in in dimensions.

[0132] The panel was first cleaned and degreased to achieve good adhesion of the coating. The metal substrate panel was first placed in a sandblaster. Mixed clean aluminum oxide grit mesh #24 and #46 (50 / 50 blend) for grit blasting on the metal surface was applied with an air pressure supply about 80 psi. The panel was sandblasted on both sides and fourSSPU 2024 / 03519 edges evenly. After sandblasting was done, the panel was handled with gloves and placed on a clean hook to hang the panel inside a spray booth.

[0133] 80 psi filtered spray air was used to blow off all dirt from the surface of the front and back of the panel. Then it was rinsed with acetone on both sides, and was allowed to air dry completely before the spraying process.

[0134] The Spraying Process:

[0135] A GEMA Powder coating system with a gun tip size #21 flat tip was used.

[0136] The coating composition was charged into the powder spray coating gun reservoir such that it was approximately half full.

[0137] Spray gun parameters were set as follows: 1) Powder Output 30%, 2) Air Volume 40%; 3) Voltage 70 kV; 4) Current 30 uA; 5) Electrode Rinsing Air 0.1 and 6) Fluidizing Air was set at 1.0.

[0138] No preheating of the metal substrate was done prior to spray coating the dry powder of the coating composition (CC).

[0139] The initial coat of 100 to 125 microns (4 to 5 mils) was applied at room temperature, after which the coated panel was placed in a circulating air oven at 330°C (626°F) for 10 minutes. Then, the coated panel was taken out of the oven and a 2ndcoat was applied, after which, the panel was again placed in an oven at 330°C for 10 minutes to achieve the target of thickness 200 to 250 microns (8 to 9 mils).

[0140] A final annealing step at 200°C (392°F) for approximately 30 minutes was added after the second heat treatment to increase the crystallinity level. Al coated with the PAEK had a thickness of 9 mils and an absolute crystallinity level of 13% as measured from DSC first heat. The absolute level of crystallinity was calculated by dividing the heat of fusion from the first heat by the theoretical heat of fusion for fully crystalline PEEK (130 J / g) and multiplying by 100.

[0141] Adhesion Testing:

[0142] The panel coated was tested for adhesion using a modified version of the ASTM Standards test method D429, Method -B. This standard was originally designed for the testing of adhesion of rubber materials to a rigid substrate and is often referred to as a T- peel or 90°-peel adhesion test.SSPU 2024 / 03520

[0143] Cutting, or even chiseling the coating could not produce a tab that is required for conducting the peel test. This demonstrated excellent adhesion of the PAEK1 mix on the aluminum substrate.

[0144] T-Bend Testing

[0145] T-bend testing of the coated panels was used to characterize the mechanical robustness of the coating and its resistance to cracking or delamination from the substrate. The test performed followed ASTM D4145. No cracking or any other defects were noted when performing this test.

Claims

SSPU 2024 / 03521ClaimsClaim 1. Method for preparing a coating layer on a metallic surface (S) of a component (CO), said component (CO) comprising metallic parts bonded by an adhesive composition (Adh), wherein the method comprises the following steps: step 1): applying a coating composition (CC) comprising as least one poly(aryl ether ketone) [noted PAEK1] having a melting temperature (Tm) of at most 330°C, preferably at most 320 °C, more preferably at most 315 °C, most preferably at most 310 °C, onto the metallic surface (S) to be coated; step 2): baking the applied coating composition (CC) whereby the metallic surface (S) is coated with a coating layer comprising the poly(aryl ether ketone); wherein PAEK1 is selected in the group consisting of PEEK-PEoEK, PEEK-PEDEK, PEEK- PEmEK, PEKK and combination thereof, preferably those with the following molar ratios: molar ratio RPEEK / RPEOEK between 65 / 35 and 85 / 15, preferably between 70 / 30 and 80 / 20; molar ratio RPEEK / RPEDEK between 65 / 35 and 85 / 15, preferably between 70 / 30 and 80 / 20; molar ratio RpEEK / RpEmEK between 65 / 35 and 90 / 10, preferably between 70 / 30 and 85 / 15; molar ratio RpEKKp / RpEEKm between 55 / 45 and 68 / 32, preferably between 57 / 43 and 65 / 35.Claim 2. Method according to claim 1 wherein component (CO) is a laminated rotor or stator comprising lamination stacks bonded by an adhesive composition (Adh).Claim 3. Method according to claim 1 or claim 2, wherein the metallic surface (S) to be coated is pretreated prior to applying the coating composition (CC), preferably with a treatment selected from flame treatment, mechanical abrasion and chemical treatment.Claim 4. Method according to any one of the preceding claims, wherein the coating composition (CC) in the powder form is applied onto the metallic surface resulting in the powder adhering to the metallic surface (S) or to a portion of the metallic substrate (S).SSPU 2024 / 03522Claim 5. Method according to any one of the preceding claims, wherein the temperature Tstep2 at which step 2) is performed is higher than the melting temperature Tm of PAEK1 (Tstep2 > Tm), being understood that in case the coating composition (CC) comprises more than one poly(aryl ether ketone), the Tm to be taken into account is the highest melting temperature of the PAEKs present in the coating composition (CC).Claim 6. Method according to any one of the preceding claims, wherein the adhesive composition (Adh) is based on a thermoset, preferably the adhesive composition is an epoxy-based adhesive composition, more preferably the adhesive composition comprises: i) an epoxy resin; ii) at least one curing agent; iii) optionally at least an accelerator.Claim 7. Method according to any one of the preceding claims, wherein the coating composition (CC) comprises, consists essentially or consists of: at least 50.0 wt% (> 50.0 wt%) of at least one semi-crystalline polymer poly(aryl ether ketone) [PAEK1], this proportion being relative to the total weight of the coating composition (CC); optionally at least one additional polymer (P) selected in the group consisting of poly(aryl ether ketone)s different from PAEK1, polysulfones (PSU), polyphenylenesulfones (PPSU), polyetherimide (PEI) and combinations thereof; optionally at least one plastic additive (Add), notably selected in the group consisting of colorants (e.g. dyes and / or pigments), impact modifiers, ultraviolet light stabilizer, heat stabilizers, antioxidants, internal lubricants and / or external lubricants, flame retardants, anti-static agents, anti-blocking agents and combinations thereof; optionally at least one flow agent. or comprises, consists essentially or consists of: at least 95.0 wt% (> 95.0 wt%) of at least one semi-crystalline polymer poly(aryl ether ketone) [PAEK1]; optionally at least one flow agent, the proportion of which being notably between 0.05 wt% and 5.0 wt%, the flow agent being notably selected in the group consisting of silica,SSPU 2024 / 03523 alumina, titanium dioxide, talc, mica, kaolin, attapulgite, calcium silicate, alumina and magnesium silicate and combination thereof; these proportions being relative to the total weight of the coating composition (CC).Claim 8. Method according to any one of the preceding claims, wherein the heat of fusion (Hm) of the PAEK [PAEK1] is at least 5.0 J / g, Hm being determined by differential scanning calorimeter (DSC) on the 2ndheat scan according to ASTM D3418-03 with a cooling and heating rate of 10 °C / min.Claim 9. Method according to any one of the preceding claims, wherein the glass transition temperature (Tg) of the PAEK [PAEK1] is between 130°C and 170 °C, Tg being determined by differential scanning calorimeter (DSC) on the 2ndheat scan according to ASTM D3418-03 with a cooling and heating rate of 10 °C / min.Claim 10. Method according to any one of the preceding claims, wherein the coating composition (CC) is in the powder form and exhibits the following parameters of distribution: a DvlO between 5.0 and 100.0 pm, preferably between 7.0 and 50.0 pm; a Dv50 between 10.0 and 200.0 pm, preferably between 20.0 and 80.0 pm; a Dv90 between 50.0 and 300.0 pm, preferably between 40.0 and 200.0 pm. or the following ones: a DvlO between 7.0 and 50.0 pm; a Dv50 between 20.0 and 80.0 pm; a Dv90 between 40.0 and 200.0 pm; where parameters DvX (X= 10, 50 or 90) are determined from a distribution in volume obtained from by laser scattering, the particles being dispersed in isopropanol.Claim 11. Method according to any one of the preceding claims, wherein PAEK1, notably the PEKK polymer, exhibits a Td(l%) of at least 490.0°C, preferably at least 495.0°C, preferably at least 500.0°C, preferably at least 505.0°C, Td(l%) representing the temperature at 1% weight loss and being measured by thermal gravimetric analysisSSPU 2024 / 03524("TGA") according to ASTM D3850, with a heating under nitrogen from 30°C to 800°C using a heating rate of 10°C / min.Claim 12. Method according to any one of the preceding claims, wherein PAEK1 or the coating composition (CC) exhibits a phosphorous content of at least 30.0 ppm, more preferably at least 40.0 ppm, most preferably at least 60.0 ppm, the P content being notably measured by Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES), notably according to the protocol present in the Experimental Section.Claim 13. Method according to claim 19 or 20, wherein the source of P consists of an inorganic phosphorous salt, notably selected in the group of dihydrogen phosphates, hydrogen phosphates and combination thereof.Claim 14. Method according to any one of the preceding claims, wherein the coating layer exhibits a level of crystallinity 1 of at least 10.0%, the level of crystallinity being determined by the following equation:1 = heat of fusion of the coating layer (J / g) / 130 (J / g) x 100 where the heat of fusion of the coating layer is measured by DSC on the 1stheat scan according to ASTM D3418-03, more particularly ASTM D3418-03, E1356-03, E793-06, E794-06 with a cooling and heating rate of 10 °C / min.Claim 15. Use of a coating composition (CC) comprising, consisting essentially or consisting of: at least 50.0 wt% (> 50.0 wt%) of at least one semi-crystalline polymer poly(aryl ether ketone) [PAEK1], this proportion being relative to the total weight of the coating composition (CC); optionally at least one additional polymer (P) selected in the group consisting of poly(aryl ether ketone)s different from PAEK1, polysulfones (PSU), polyphenylenesulfones (PPSU), polyetherimide (PEI) and combinations thereof; optionally at least one plastic additive (Add), notably selected in the group consisting of colorants (e.g. dyes and / or pigments), impact modifiers, ultraviolet light stabilizer, heatSSPU 2024 / 03525 stabilizers, antioxidants, internal lubricants and / or external lubricants, flame retardants, anti-static agents, anti-blocking agents and combinations thereof; optionally at least one flow agent; for the preparation of a polymer coating on the metallic surface (S) of a laminated rotor or stator comprising lamination stacks, notably bonded by an adhesive composition (Adh); the coating composition being as defined in the preceding claims.

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