Method for producing hollow composite parts with a bladder molding technique

Abstract

Described herein is a process for manufacturing by airbag molding a hollow composite part made of or containing a thermoplastic composite (TPC), the process comprising the step of placing a preform of the thermoplastic composite (TPC) around an expandable airbag; wherein the thermoplastic composite (TPC) comprises: a polymer matrix (PM) comprising or consisting of: (i) at least one thermoplastic polymer; and (ii) optionally at least one plastic additive blended with the thermoplastic polymer; and continuous fibers embedded in the polymer matrix (PM); and wherein the airbag is made of or contains a polymer composition (PC) comprising, consisting essentially of or consisting of at least one polyamide-imide (PAI), optionally at least one filler and optionally at least one polymer additive.

Description

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 597,223, filed November 8, 2023, and European Patent Application No. 23210989.2, filed November 20, 2023, the contents of which are incorporated herein by reference in their entirety for all purposes. In the event of any inconsistency between this application and one of the preceding applications that would affect the clarity of terminology or expression, reference should be made solely to this application. Technical Field

[0002] This invention relates to a method for preparing hollow composite material parts, particularly hollow tubular composite material parts, made of or containing thermoplastic composite materials (TPC) using airbag molding technology (also known as airbag inflation (BIM)), wherein the thermoplastic composite material is particularly based on thermoplastic polymers that require processing at high temperatures. Background Technology

[0003] In the manufacture of aerospace-grade composite components, the benefits of thermoplastic composites are recognized, such as rapid processing and improved material properties compared to those achievable with thermoset composites. However, complex thermoplastic composite components are sometimes not easily obtained in a reproducible and industrially viable manner.

[0004] Airbag molding technology is known in the field of thermoplastic composites for manufacturing hollow components with complex shapes, such as hollow tubes. This technology is disclosed, for example, in “Optimizing Bladder Resin Transfer Molding Process to Manufacture Complex, Thin-Ply Thermoplastic Tubular Composite Structures: An Experimental Case Study” Polymers 2021, 13(23), 4093 (https: / / doi.org / 10.3390 / polym13234093). Figure 1 of this article is a schematic diagram of the airbag molding technology. It is also disclosed in WO 2008 / 101258.

[0005] EP 1275491 A1 discloses this technique for producing hollow shapes from fiber-reinforced composites, wherein an expandable air bladder pressurized with air is placed inside the preform before being placed in a mold. Once the mold is closed, the air bladder is inflated to the desired pressure, and the mold is heated at a temperature above the melting point of the matrix to allow the fibers to be impregnated. After the thermoplastic melt has flowed around the fibers and formed a continuous phase, the mold can be cooled and the part can be demolded.

[0006] Airbag molding technology is also disclosed in EP 3785875 B1 or EP 3756846 A1.

[0007] US Patent 2011 / 0003163 discloses a method for preparing thermoplastic composites made of PEEK using airbag molding technology. The airbags can be made from different polymers, such as polyaryletherketone, polyarylethersulfone, polyphenylene sulfide, polyetherimide, polyamide, or polyolefin.

[0008] JP H10 217321 (18.08.1998) (Application No. JP19930131506) (D1) discloses a method for molding composite materials made from prepregs using heat-resistant thermoplastic resins (such as polycarbonate, polysulfone, thermoplastic polyimide polymers or fluorine-based polymers).

[0009] EP 3756846 (D2) discloses a method for preparing thermoplastic composites using airbag molding technology, wherein the airbag is made of polyimide.

[0010] WO 2013 / 040522 (D3) disclosed airbags in an unrelated field. Technical issues

[0011] There is a need for a method to manufacture complex hollow parts made from thermoplastic composites based on thermoplastic plastics that require high processing temperatures (e.g., > 400°C).

[0012] Furthermore, in the case of airbag molding technology, the airbags used in the fabrication need to exhibit a good balance of mechanical properties, especially impact toughness and fracture toughness.

[0013] The method of the present invention aims to solve this technical problem. Brief description of the invention

[0014] The present invention is as defined in the appended set of claims.

[0015] The present invention relates to a method as disclosed in any one of claims 1-19.

[0016] The present invention also relates to uses as defined in any one of claims 20-22 or 23-25.

[0017] The present invention also relates to a method for preparing an expandable airbag as defined in any one of claims 26-32.

[0018] More precise information and details on these topics are now provided below. Attached Figure Description

[0019] Figure 1 / 2 This image shows the 3D-printed scaffold prepared in the experimental section.

[0020] Figure 2 / 2 This image shows the airbags prepared in the experimental section. definition

[0021] wt% means percentage by weight. mol% means percentage by mole.

[0022] Unless otherwise specified, this applies to all numerical ranges (including those without upper or lower limits), including the endpoints.

[0023] The proportion of repeating units in a polymer is expressed in mol% and relative to the total number of repeating units in the polymer.

[0024] In this application, unless otherwise indicated, any specific embodiment or technical feature related to the subject matter of the invention is applicable to and interchangeable with another embodiment or technical feature that is also related to the same subject matter and disclosed elsewhere in this application.

[0025] Any part of this application disclosed and related to TPC, expandable airbags, thermoplastic polymers of TPC or thermoplastic polymer blends, PAI, precursors (P Any features, characteristics, or details relating to Z, Q, or the stent are applicable to any invention or claim disclosed herein. Detailed Implementation

[0026] As a first aspect, the present invention relates to a method for manufacturing hollow composite material parts made of or containing thermoplastic composite material by airbag molding, the method comprising the step of placing a preform of thermoplastic composite material (TPC) around an expandable airbag.

[0027] Thermoplastic composites (TPCs) include:

[0028] ■ A polymer matrix (PM) comprising or consisting of: (i) at least one thermoplastic polymer; and (ii) optionally at least one plastic additive blended with the thermoplastic polymer; and

[0029] ■ Continuous fibers embedded in a polymer matrix (PM);

[0030] Furthermore, the airbag is made of or contains a polymer composition comprising at least one polyamide-imide (PAI) as defined herein.

[0031] PAI possesses a favorable combination of processing window and mechanical properties, enabling the inflation of air bladders under high temperatures and pressures, and even its use in the fabrication of complex hollow components. Therefore, this method is suitable when it is necessary to prepare thermoplastic composites from thermoplastic polymers that require processing at high temperatures.

[0032] Hollow composite material components can have various shapes and / or exhibit variable cross-sections. Examples of hollow composite material components include tubes, handlebars, forks, golf club shafts, or bicycle frames. The method of this invention is suitable for manufacturing complex hollow composite material components.

[0033] The method of the present invention is particularly suitable for preparing non-axisymmetric hollow composite material parts.

[0034] This method typically includes the following steps:

[0035] (1) Place the preform of thermoplastic composite (TPC) that has been placed around the airbag into the mold;

[0036] (2) After the mold is closed, the expandable airbag is inflated so as to compress the preform against the mold wall;

[0037] (3) Apply heat to allow the polymer components of the polymer matrix (PM) to flow and solidify;

[0038] (4) After cooling, remove the hollow composite material parts from the mold;

[0039] (5) The airbag may be removed from the formed hollow composite material component.

[0040] Step 1

[0041] In step 1), a preform of thermoplastic composite (TPC) surrounding the expandable airbag is placed in a mold. The preform contains the same components as the final TPC: (i) at least one thermoplastic polymer and (ii) optionally at least one plastic additive and continuous fibers.

[0042] Preforms can be more specifically selected from the following groups: uniaxial (1D), biaxial (2D), 2.5D, and triaxial (3D) types.

[0043] Preforms can be more specifically woven preforms, which contain fibers of unidirectional material that have already been woven.

[0044] The mold is usually made of metal to allow for good heat transfer in step 3).

[0045] An airbag is placed in the cavity of the mold so that when the airbag is inflated, it presses the preform against the wall of the mold.

[0046] The pressure applied via the airbag can be applied according to a predetermined pattern. This pattern can be an iterative increase and decrease of the applied pressure. An example of a pattern for applying pressure via the airbag is disclosed in EP 3756846.

[0047] Regarding expandable airbags

[0048] The shape and geometry of the airbag are adapted to the internal shape of the composite component, and when inflated, it can substantially conform to that internal shape, thereby applying pressure to the surface of the composite laminate.

[0049] The airbag includes at least one opening to allow the introduction of fluid (such as gas) to inflate the airbag.

[0050] The thickness of the airbag is typically between 30.0 and 500.0 µm, preferably between 50.0 and 300.0 µm, and more preferably between 50.0 and 150.0 µm. This thickness allows the airbag to inflate inside the mold without rupturing, especially when the temperature rises.

[0051] The airbag is made of or contains a polymer composition (PC) comprising, substantially comprising, or comprising of: at least one polyamide-imide (PAI), optionally at least one filler, and optionally at least one polymer additive (different from the filler). The proportion of PAI in the polymer composition (PC) is typically between 80.0 and 100.0 wt%, based on the weight of the polymer composition (PC).

[0052] According to a preferred embodiment of this disclosure, the polymer composition (PC) comprises, is substantially composed of, or is composed of at least one polyamide-imide (PAI) and optionally at least one polymer additive.

[0053] According to another preferred embodiment of this disclosure, the polymer composition (PC) comprises, is substantially composed of, or consists of at least one polyamide-imide (PAI).

[0054] The filler can be selected from the following groups: calcium carbonate, magnesium carbonate, glass fiber, graphite, carbon black, carbon fiber, graphene, graphene oxide, fullerene, talc, wollastonite, mica, alumina, silicon dioxide, titanium dioxide, kaolin, silicon carbide, zirconium tungstate, boron nitride, and combinations thereof.

[0055] Polymer additives may be selected from the group consisting of: colorants, dyes, pigments, lubricants, plasticizers, flame retardants, toughening agents, nucleating agents, heat stabilizers, light stabilizers, antioxidants, processing aids, and combinations thereof.

[0056] Regarding PAI

[0057] In the context of this invention, PAI represents a composition containing at least 90.0 mol% repeating units (R). PAIa ) and (R PAIb The polymer, this ratio is based on the total number of repeating units of PAI:

[0058] (R PAIa )

[0059] (R PAIb )

[0060] Where Z is derived from substituted or unsubstituted C6-C. 20 The divalent groups of aromatic diamines. These units are linked to each other by amide bonds.

[0061] The amide bond connecting the repeating unit of PAI is typically prepared by polycondensation of at least one aromatic diamine having the formula H2N-Z-NH2 and trimellitic acid chloride in a polar (typically aprotic) organic solvent.

[0062] Those skilled in the art should understand that in units containing acid and amide groups [i.e., having the formula (R PAIa In the unit (ia)-(iiia)], the CO group on the left side of the aromatic ring with two other CO groups can be in the ortho or para position relative to the COOH group. The unit with an imide group [i.e., having the formula (R...] PAIb The units (ib)-(iiib) are obtained by imidization of the corresponding units with acid and amide groups.

[0063] Z is specifically chosen from the following groups:

[0064]

[0065] And combinations of two or more of the said groups,

[0066] Where Q is -O-, -S-, -C(O)-, -SO2, -SO-, -C y H 2y - where y is an integer from 1 to 5.

[0067] Z is specifically chosen from the following groups: , And a combination of two of the divalent groups.

[0068] According to embodiments of the invention, Q is more particularly -O- or -C. y H 2y -

[0069] According to embodiments of the invention, Q is more particularly -O- or -CH2-.

[0070] According to embodiments of the present invention, Z is any group disclosed herein.

[0071] According to embodiments of the present invention, Q is any group disclosed herein.

[0072] Repeating unit (R) PAIa More specifically, choose from the following groups:

[0073] (ia)

[0074] (iia)

[0075] (iiia)

[0076] And combinations of two or more of the repeating units.

[0077] The repeating unit (R) generated by imidization of the above repeating units (ia)-(iiia) PAIb More specifically, choose from the following groups:

[0078] (ib)

[0079] (iib)

[0080] (iiib)

[0081] And combinations of two or more of the repeating units.

[0082] According to a preferred embodiment, the repeating unit of PAI is based on Z = where Q = -CH2-. .

[0083] According to another preferred embodiment, the repeating unit of PAI is based on Z = where Q = -O-. and Z= The combination of these factors is advantageous. The proportion was between 50.0 and 90.0 mol%, and The proportions are between 10.0 and 50.0 mol%. These proportions can also be between 60.0 and 80.0 mol% and between 20.0 and 40.0 mol%, respectively.

[0084] Repeating unit (R) in PAI PAIa ) and (R PAIb The total proportion of (PAI) is at least 90.0 mol%, preferably at least 95.0 mol%, and more preferably at least 99.0 mol%. According to a preferred embodiment, the repeating unit of (PAI) consists of repeating unit (R). PAIa ) and (R PAIb Composition.

[0085] PAI is characterized by a high proportion of imidized repeating units. In PAI, the molar ratio R = units with imide groups / [units with imide groups + units with acid and amide groups] is at least 90.0 mol%, preferably at least 95.0 mol%. R can be 100.0%. R can be between 95.0% and 100.0%.

[0086] The ratio of units with imide groups to units with acid and amide groups was determined using standard analytical techniques such as infrared spectroscopy.

[0087] Therefore, R equals (R PAIb ) / [(R PAIa )+(R PAIb )).

[0088] PAI's number-average molecular weight M n Typically, it is at least 25,000 g / mol. Similarly, the weight-average molecular weight M of PAI... w Typically, it is at least 75,000 g / mol. M n and M w It was determined in DMAC by size exclusion chromatography (SEC) using polystyrene standards and a UV detector.

[0089] Precursor (P) Preparation of (PAI)

[0090] Precursor (P) It solidifies into PAI.

[0091] Precursor (P) It is prepared by a method including the following step (i): polycondensing at least one aromatic diamine having the formula H2N-Z-NH2 with trimellityl chloride in a polar (typically aprotic) organic solvent.

[0092] PAI includes making the precursor (P) The curing step (ii) is used to obtain the precursor (P). ) Contains repeating units (R) PAIa ) and (R PAIb It is characterized by a high proportion of repeating units having acid and amide groups. Molar ratio R = The number of units with acid and amide groups / [units with imide groups + units with acid and amide groups] is indeed at least 80.0 mol%. R It can be 100.0%. R It can be between 80.0% and 100.0%. Curing step (ii) involves cyclization and the formation of imide bonds.

[0093] PAI is therefore prepared by a method including the following steps:

[0094] (i) By reacting trimellityl chloride with at least one aromatic diamine having the formula H2N-Z-NH2 via a polycondensation reaction to obtain a precursor of PAI (P );

[0095] (ii) The precursor (P) It solidifies into PAI.

[0096] Regarding step (i)

[0097] The polycondensation reaction is preferably carried out with trimellityl chloride in excess relative to the aromatic diamine monomer. Trimerictyl chloride is typically present in the reaction mixture in an excess of at least 1.0 mol% relative to the equimolar proportion of the aromatic diamine monomer present in the reaction mixture.

[0098] The polycondensation reaction in step (i) is advantageously carried out under substantially anhydrous conditions in a polar solvent and at a temperature below 150°C. Polar solvents are generally selected from the group consisting of at least one of the following: N-methyl-2-pyrrolidone (NMP), dimethylacetamide (DMAC), dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N-butylpyrrolidone, N-acetylpyrrolidone, methyl 5-(dimethylamino)-2-methyl-5-oxovalerate, dimethyldecylamide, 2-hydroxy-N,N-dimethylpropionamide, isosorbide dimethyl ether, 2-isobutyl-2-methyl-1,3-dioxolane-4-methanol, cyclopentanone, γ-valerol, mixtures comprising ethyl lactate and ethyl esters derived from soybean oil or corn oil, dimethyl glutarate, dimethyl succinate, dimethyl adipate, a mixture of dimethyl glutarate, dimethyl succinate, dimethyl adipate and 2-methylglutarate.

[0099] Precursor (P) The molecular weight of ) is preferably low, so that it contains the precursor (P) The solution of the composition has a low viscosity. This in particular ensures that the composition can be easily coated onto the scaffold. Precursor (P) The number-average molecular weight M n Preferably below 7,000 g / mol. M n Advantageously, the concentration can be between 1,000 and 7,000 g / mol or between 2,000 and 5,000 g / mol.

[0100] Precursor (P) The weight-average molecular weight M w Typically below 20,000 g / mol. Mw can be between 10,000 and 15,000 g / mol.

[0101] M n and M w Both were determined under the conditions given above.

[0102] Precursor (P) Preferably, it has an acid value of at least 50.0 mg KOH / g polymer as measured according to ASTM D664.

[0103] Regarding step (ii)

[0104] The temperature for the curing step (ii) should be high enough to cure the precursor (P) The precursor (P) is cured into PAI. This temperature is typically at least 180°C. In the context of this invention, once the precursor (P) is cured into PAI... Once applied to the support, proceed to step (ii).

[0105] The following details the curing process for step #2.

[0106] Preparation of expandable airbags

[0107] The expandable airbag used in the method of the present invention is prepared by a method comprising the following steps:

[0108] #1: The precursor containing PAI (P A solution of the composition is coated onto the support;

[0109] #2: Heating the coated support to which the composition has been applied;

[0110] #3: Degrade or dissolve the stent in a suitable solvent.

[0111] Step #1 involves using a precursor (P) containing PAI. A solution of the composition. This step can be repeated several times to obtain a coating with the desired thickness. The composition comprises or consists of the following: precursor (P ), optionally at least one filler and optionally at least one polymer additive.

[0112] Precursor (P) The composition is in a solution in a polar solvent or mixture of polar solvents as defined above (such as water and a polar solvent, especially a mixture of polar solvents as defined above). The composition can be, for example, in a solution of a mixture of water and N-methylpyrrolidone (NMP). Examples of solutions include: a precursor (P) at concentrations between 10.0 and 90.0 wt%. This ratio is based on the total weight of the solution.

[0113] The precursor can be, for example, Torlon. ® AI-10 or Torlon ® Both 4000T and 4000T are commercialized by Solvay Specialty Polymers USA, LLC.

[0114] Step #2 allows for the removal of the remaining solvent and the removal of the precursor (P) The precursor is cured into a polymeric substance (PAI). This step can be performed in at least two sub-steps. For example, heating step #2 can be performed in a first heating sub-step at a temperature below 110°C or below 100°C and a second heating sub-step at a temperature of at least 180°C. The first sub-step helps to remove the solvent. The second sub-step is intended to cure the precursor into a PAI. An example of a temperature profile could be as follows: the first sub-step is performed at 100°C for 24 hours, and the second sub-step is performed at 200°C for 48 hours.

[0115] Step #2 preferably involves heating at a temperature of at least 180°C. This in particular ensures that the PAI membrane exhibits sufficient strength and mechanical resistance.

[0116] The scaffold can be fabricated by additive manufacturing methods (such as fused deposition modeling) or by injection molding.

[0117] Additive manufacturing enables the production of 3D-printed scaffolds with required, even complex, geometries. The scaffolds are made of thermoplastic polymers that need to exhibit high glass transition temperatures (Tg) and / or melting temperatures (Tm) and be able to degrade or dissolve in suitable solvents without affecting the PAI (glass transition temperature). Thermoplastic polymers typically exhibit a glass transition temperature (Tg) and / or melting temperature (Tm) of at least 200°C. Tg and Tm are determined by DSC (differential scanning calorimetry), particularly according to ASTM D3418.

[0118] The scaffold typically comprises or is made of a thermoplastic polymer. The thermoplastic polymer of the scaffold is advantageously selected from the group consisting of polyetherimide (PEI), polyethersulfone (PESU), poly(glycolic acid), and polyphenylsulfone (PPSU).

[0119] In the context of this invention, PEI is a polymer comprising repeating units having formula (II):

[0120] (II)

[0121] The divalent T portion bridges the 3,3′, 3,4′, 4,3′, or 4,4′ positions of the aryl ring of the corresponding aryl imide moiety; T is -O- or a group having the formula -OWO-; W is a divalent group selected from the group consisting of:

[0122] , and X can be freely selected from -C(O)-, -SO2-, -O-, S and -C y H 2y- A group consisting of y, where y is an integer from 1 to 5, and q is 0 or 1; and where R is a divalent organic group selected from (a) C6-C 20 Aromatic hydrocarbon groups and their halogenated derivatives, (b) C2-C 20 alkylene group, (c) C3-C 20 cycloalkyl groups, and (d) having the formula The divalent group, where Q is a covalent bond or selected from -C(O)-, -SO2-, -C y H 2y Members of the group consisting of -, O- and -S-, where y is an integer from 1 to 5.

[0123] More specifically, R is independently p-phenylene or m-phenylene, and T is a divalent group of the following:

[0124] PEI comprises repeating units formed by the condensation polymerization of 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride with a diamine selected from the group consisting of p-phenylenediamine, m-phenylenediamine, and combinations of the two diamines.

[0125] PEI typically exhibits a melt index of 0.1 to 10.0 g / min as measured by ASTM D 1238 at 337°C / 6.6 kg.

[0126] Step 2

[0127] In step 2), after the mold is closed, the air bladder is inflated to compress the preform against the mold surface.

[0128] The airbag can be inflated using air or nitrogen.

[0129] Step 3

[0130] In step 3), heat is applied to melt the thermoplastic polymer.

[0131] Steps 2) and 3) are used to solidify the preform.

[0132] Step 3) can be performed after step 2) or simultaneously with step 2).

[0133] Thermoplastic composites (TPC)

[0134] Thermoplastic composites (TPCs) include:

[0135] ■ A polymer matrix (PM) comprising or consisting of: (i) at least one thermoplastic polymer; and (ii) optionally at least one plastic additive blended with the thermoplastic polymer; and

[0136] ■ Continuous fibers embedded in a polymer matrix (PM).

[0137] The method of this invention is applicable to any type of TPC.

[0138] The proportion of continuous fibers in thermoplastic composites (TPCs) is typically between 40.0 and 80.0 vol%, and more particularly between 50.0 and 70.0 vol%, based on the total volume of the thermoplastic composite (TPC).

[0139] The proportion of polymer matrix (PM) in thermoplastic composites (TPCs) is typically between 20.0 and 60.0 vol%, and more specifically between 30.0 and 50.0 vol%, based on the total volume of the thermoplastic composite (TPC).

[0140] The proportion expressed as vol% is typically derived from the ratio of fiber to polymer matrix expressed as wt% and obtained by assuming there are no voids in the composite material. Therefore, the fiber proportion in vol% = x 100, where V 纤维 and V TPC It is the volume of the fiber and composite material, where, according to the assumption, V TPC = V 纤维 + V 基质。 Fiber volume V 纤维 and the volume V of the matrix 基质 It is calculated from the weight and density of the fiber and matrix. Similarly, the proportion of the matrix, expressed as a vol%, = x100.

[0141] The thermoplastic polymer or thermoplastic polymer blend in a thermoplastic composite (TPC) can be semi-crystalline or amorphous. It is preferably semi-crystalline.

[0142] Continuous fibers can advantageously be selected from the group consisting of carbon fibers, glass fibers, aramid fibers, basalt fibers, ceramic fibers, and combinations thereof. Continuous carbon fibers are advantageously preferred.

[0143] In the case of semi-crystalline thermoplastics, the thermoplastic polymer or blends thereof preferably exhibit a heat of fusion (Hg) of at least 5.0 J / g, more preferably at least 10.0 J / g or at least 15.0 J / g. f More specifically, the heat of fusion (H₂O)f The area was determined to be the area under endothermic melting during the second heating scan.

[0144] The semi-crystalline thermoplastic polymer preferably exhibits a melt temperature (Tm) of at least 200°C, more preferably at least 260°C, and more preferably at least 300°C. Tm is determined by DSC. More specifically, Tm is determined during a second heating scan.

[0145] Heat of fusion (H) f The melting temperature (Tm) and melting point are determined by DSC (differential scanning calorimetry), and in particular according to ASTM D3418.

[0146] thermoplastic polymers

[0147] This invention is applicable to a wide range of polymer matrices (PM) and a wide range of thermoplastic polymers.

[0148] Thermoplastic polymers may be more specifically selected from the group consisting of: polyaryletherketone polymers (PAEK), polyphenylene sulfide polymers (PPS), polyamides (especially polyphthalamide (PPA)), poly(arylether sulfone) polymers (PAES), polypropylene, polyethylene terephthalate (PET), polyetherimide (PEI), and combinations thereof.

[0149] Thermoplastic polymers may be more specifically selected from the group consisting of: polyaryletherketone polymers (PAEK), polyphenylene sulfide polymers (PPS), polyphthalamides (PPA), poly(arylether sulfone) polymers (PAES), polyetherimides (PEI), and combinations thereof.

[0150] Thermoplastic polymers can be more specifically PAEK.

[0151] PAEK

[0152] "Poly(aryl ether ketone)" (abbreviated as PAEK in this document) refers to a polymer having ether and ketone bonds between its units, wherein these units conform to the formula -Q-Ar-, where Ar is a group selected from the group consisting of phenylene, biphenylene, or naphthylene, and Q is -O- or -C(=O)-, where each Q of one repeating unit is bonded to the Ar of another unit. For example, for PEEK, Ar = 1,4-phenylene and Q = -O- (ether bond) and -C(=O)- (ketone bond).

[0153] According to embodiments of the present invention, polyaryletherketone polymer (PAEK) means containing more than 50.0 mol% repeating units (R PAEKThe polymer, wherein these repeating units are selected from the group consisting of units having the following formulas (JA) to (JQ):

[0154]

[0155]

[0156]

[0157]

[0158]

[0159] One of the units has an -O- or -C(=O)- group bonded to an aryl group of the other unit, and wherein:

[0160] - R' j’ Each R' may be the same as or different from the others, and is selected from the group consisting of: halogens, alkyl, alkenyl, alkynyl, aryl, ethers, thioethers, carboxylic acids, esters, amides, imides, alkali metal or alkaline earth metal sulfonates, alkyl sulfonates, alkali metal or alkaline earth metal phosphonates, alkyl phosphonates, amines, and quaternary ammonium compounds; and

[0161] - j' is zero or an integer in the range of 1 to 4.

[0162] In the repeating unit (R) PAEK In this context, the corresponding phenylene moiety can independently possess the same characteristics as the repeating unit (R). PAEK The other portions of the phenylene moiety are 1,2-linked, 1,4-linked, or 1,3-linked. Preferably, the phenylene moiety has 1,3-linked or 1,4-linked bonds.

[0163] j' is preferably zero each time it appears.

[0164] Repeating units (R) in PAEK PAEK The proportion of ) is advantageously at least 60.0 mol%, or at least 70.0 mol%, or at least 80.0 mol%, or at least 90.0 mol%, or at least 95.0 mol%, or at least 99.0 mol%. According to the examples, all repeating units of the PAEK polymer are repeating units (R... PAEK ).

[0165] According to embodiments, the thermoplastic polymer is selected from the group consisting of: poly(ether ether ketone) (PEEK), poly(ether ketone ketone) (PEKK), poly(ether ketone) (PEK), poly(ether ether ketone ketone) (PEEKK), PEDEKK, PEEK-PEDEK, PEEK-PEoEK, and blends of two or more of the polymers.

[0166] According to embodiments, the thermoplastic polymer is selected from the group consisting of: poly(ether ether ketone) (PEEK), poly(ether ketone ketone) (PEKK), and blends of two or more of the polymers.

[0167] PEEK: As used herein, “poly(etheretherketone) (PEEK)” refers to a polymer in which more than 96.0 mol% of repeating units have the formula (J'-A):

[0168] (J'-A)

[0169] These repeating units are bonded to each other via O (ether linkage).

[0170] The proportion of repeating units (J'-A) in PEEK can more specifically be at least 99.0 mol%. According to the embodiment, all repeating units in PEEK are repeating units (J'-A).

[0171] The melt flow rate of PEEK, as measured according to ASTM D1238 (400°C, 2.16 kg), can be between 1.0 and 50.0 g / 10 min.

[0172] Examples of readily usable PEEK are the Ketaspire KT880 or KT820, commercially available from Solvay Specialty Polymers, Inc.

[0173] PEKK: As used herein, “poly(etherketoneketone) (PEKK)” indicates a polymer in which more than 95.0 mol% of the repeating units are combinations of repeating units having formula (J'-B) and formula (J''-B):

[0174] (J'-B) and

[0175] (J''-B)

[0176] These repeating units are bonded to each other via O (ether linkage).

[0177] The proportion of repeating units (J'-B) and (J''-B) in PEKK can more specifically be at least 99.0 mol%. According to an example, all repeating units in PEKK are repeating units (J'-B) and (J''-B).

[0178] The molar ratio (J'-B) / (J''-B) is selected such that the polymer is semi-crystalline. The molar ratio (J'-B) / (J''-B) is preferably greater than 60 / 40. The molar ratio (J'-B) / (J''-B) is preferably between 60 / 40 and 90 / 10, or between 65 / 35 and 80 / 20.

[0179] PEKK can be prepared by nucleophilic polycondensation of a reaction mixture containing a monomer and a base having the following formula, wherein the base is selected from the group consisting of Na2CO3, K2CO3, and combinations thereof:

[0180] X is F (bis(fluorobenzoyl)benzene monomer) or OH (bis(hydroxybenzoyl)benzene monomer), provided that the molar ratio of bis(fluorobenzoyl)benzene monomer / bis(hydroxybenzoyl)benzene monomer is substantially close to 1.0 (this polycondensation will be referred to as the "nucleophilic route"). The molar ratio of bis(fluorobenzoyl)benzene monomer / bis(hydroxybenzoyl)benzene monomer is typically about 0.9:1 to about 1:0.9, more preferably 0.95:1 to 1:0.95, most preferably about 0.97:1 to about 1:0.97, and most preferably between 0.97:1 and 1.00:1. Examples following this nucleophilic route are described, for example, in EP 3559084 B1.

[0181] PEKK can also be prepared by polycondensation of a reaction mixture comprising diphenyl ether, terephthaloyl chloride, isophthaloyl chloride, and a Lewis acid (this polycondensation will be referred to as the "electrophilic line"). Examples of preparation methods following this electrophilic line are described, for example, in WO 2014 / 013202.

[0182] The available PEKK instance is the Kepstan 7002, commercially available from Arkema.

[0183] PEK: As used herein, “poly(ether ketone) (PEK)” means any polymer in which more than 95.0 mol% of repeating units have the formula (J'-C):

[0184]

[0185] The proportion of repeating units (J'-C) in PEK can more specifically be at least 99.0 mol%. According to the embodiment, all repeating units in PEK are repeating units (J'-C).

[0186] PEEKK: As used herein, “poly(etheretherketoneketone) (PEEKK)” means any polymer in which more than 95.0 mol% of repeating units have the formula (J'-M):

[0187]

[0188] The proportion of repeating units (J'-M) in PEEKK can more specifically be at least 99.0 mol%. According to the embodiment, all repeating units in PEEKK are repeating units (J'-M).

[0189] PEDEKK: “PEDEKK” indicates any repeating unit (R) with more than 95.0 mol% repeating percentage. PAEK ) is a polymer having a combination of repeating units of the formula (J'-Q) and (J''-Q):

[0190] (J'-Q)

[0191] (J''-Q).

[0192] The proportion of repeating units (J'-Q) and (J''-Q) in PEDEKK can more particularly be at least 99.0 mol%. According to an example, all repeating units in PEDEKK are repeating units (J'-Q) and (J''-Q).

[0193] PEEK-PEDEK: PEEK-PEDEK represents any polymer in which more than 95.0 mol% of the repeating units are combinations of repeating units having the formula (J'-A) and (J'-D):

[0194] (J'-D)

[0195] These repeating units are bonded to each other via O (ether linkage).

[0196] PEEK-PEDEK copolymers are prepared by nucleophilic polycondensation of the following monomers: hydroquinone, 4,4-difluorobenzophenone, and 4,4'-dihydroxybiphenyl (Formula: ).

[0197] The proportion of repeating units (J'-A) and (J'-D) in PEEK-PEDEK can more particularly be at least 99.0 mol%. According to an example, all repeating units in PEEK-PEDEK are repeating units (J'-A) and (J'-D).

[0198] PEEK-PEoEK: PEEK-PEoEK represents any polymer in which more than 95.0 mol% of the repeating units are combinations of repeating units having the formula (J'-A) and (J''-A):

[0199] (J''-A)

[0200] These repeating units are bonded to each other via O (ether linkage).

[0201] PEEK-PEoEK is prepared by nucleophilic polycondensation of the following monomers: hydroquinone, 4,4-difluorobenzophenone, and pyrocatechol.

[0202] The molar ratio (J'-A) / (J''-A) can be between 95 / 5 and 5 / 95. This molar ratio can preferably be between 70 / 30 and 95 / 5.

[0203] All PAEKs disclosed in this section are prepared using conventional polycondensation techniques well known in the art, particularly via nucleophilic or electrophilic routes. More specifically, PAEKs can be prepared by nucleophilic aromatic substitutions in which diaryl ether bonds are obtained. Polycondensation is typically carried out in solvents such as diphenyl sulfone at 300°C or higher with the aid of bases such as Na₂CO₃ and / or K₂CO₃. Some details regarding polycondensation involving nucleophilic substitution can be found, for example, in US 4,176,222 or WO 2021 / 008983. For example, PEEKs are prepared via a nucleophilic route through the polycondensation of 4,4-difluorobenzophenone and hydroquinone.

[0204] PAEK polymers can be prepared via Friedel-Crafts electrophilic substitution, in which diaryl ketones are linked. Polycondensation is typically carried out in a solvent at temperatures below 150°C using Lewis acids such as AlCl3. Details regarding polycondensation involving Friedel-Crafts electrophilic substitution can be found, for example, in US 4,841,013, US 4,816,556, WO 2011 / 004164, and WO 2014 / 013202. For example, PEKK can be prepared via the electrophilic polycondensation of 4,4-dichlorobenzene, m- and terephthaloyl chlorides.

[0205] PPS polymer

[0206] PPS represents any repeating unit (R) containing at least 50.0 mol.% of the formula (L). PPS Polymers of:

[0207] (L)

[0208] These repeating units are bonded to each other via S (sulfide bonds).

[0209] The proportion of repeating units (L) may be at least 60.0 mol.%, or at least 70.0 mol.%, or at least 80.0 mol.%, or at least 90.0 mol.%, or at least 95.0 mol.%, or at least 99.0 mol.%.

[0210] According to the embodiment, all repeating units (R) in PPS PPS All of them are repeating units with the formula (L).

[0211] PPS polymers are prepared using conventional polycondensation techniques well known in the art. More specifically, PPS polymers can be prepared by heating a reaction mixture comprising at least one p-dihalobenzene compound (such as p-dichlorobenzene) and a sulfur compound in a polar aprotic solvent. The sulfur compound is typically an alkali metal sulfide, such as Na₂S. In some embodiments, the alkali metal sulfide is generated in situ from an alkali metal hydrogen sulfide and an alkali metal hydroxide. Na₂S can be generated in situ from NaSH and NaOH. The polymerization temperature typically occurs at at least 150°C, and more particularly at at least 200°C.

[0212] The melt flow rate of PPS, as measured according to ASTM D1238 (316°C, 5 kg), can be between 1.0 and 50.0 g / 10 min.

[0213] A readily usable example of PPS is the Ryton QA200N, commercially available from Solvay.

[0214] PAES

[0215] Poly(aryl ether sulfone) (PAES) means containing at least 50 mol.% of repeating units (R) having the formula (K). PAES Polymers of:

[0216] (K)

[0217] Each R may be the same as or different from the others, and is selected from halogens, alkyl, alkenyl, alkynyl, aryl, ether, thioether, carboxylic acid, ester, amide, imide, alkali metal or alkaline earth metal sulfonates, alkyl sulfonates, alkali metal or alkaline earth metal phosphonates, alkyl phosphonates, amines, and quaternary ammonium.

[0218] Each h is either the same as or different from the others, and is an integer ranging from 0 to 4; and

[0219] T is selected from the following groups: bonds, sulfone groups [S(=O)2], and -C(R) groups. j (R) k )-, where R j and R k They may be the same as or different from each other, selected from hydrogen, halogen, alkyl, alkenyl, alkynyl, ether, thioether, carboxylic acid, ester, amide, imide, alkali metal or alkaline earth metal sulfonates, alkyl sulfonates, alkali metal or alkaline earth metal phosphonates, alkyl phosphonates, amines, and quaternary ammonium. R j and R k Preferably, it is methyl.

[0220] Preferably, at least 60.0 mol.%, or at least 70.0 mol.%, or at least 80.0 mol.%, or at least 90.0 mol.%, or at least 95.0 mol.%, or at least 99 mol.% of the repeating units in the PAES are repeating units (R). PAES Most preferably, all repeating units in PAES are repeating units (R). PAES ).

[0221] Advantageously, the PAES polymer is selected from the group consisting of polyphenylsulfone (PPSU), polyethersulfone (PES), and polysulfone (PSU).

[0222] Polyphenylsulfone (PPSU) refers to a polymer containing more than 50 mol.% of repeating units of the formula (K'-A):

[0223] (K'-A).

[0224] Preferably, at least 60.0 mol.%, or at least 70.0 mol.%, or at least 80.0 mol.%, or at least 90.0 mol.%, or at least 95.0 mol.%, or at least 99 mol.% of the repeating units in the PPSU are repeating units (K'-A). Most preferably, all repeating units in the PPSU are repeating units (K'-A).

[0225] PPSU can be prepared by known methods, and especially by RADEL from Solvay Specialty Polymers, Inc. ®PPSU is available.

[0226] Polyethersulfone (PES) refers to a polymer containing at least 50 mol.% of repeating units having the formula (K'-B):

[0227] (K'-B).

[0228] Preferably, at least 60.0 mol.%, or at least 70.0 mol.%, or at least 80.0 mol.%, or at least 90.0 mol.%, or at least 95.0 mol.%, or at least 99 mol.% of the repeating units in the PES are repeating units (K'-B). Most preferably, all repeating units in the PES are repeating units (K'-B).

[0229] PES can be prepared by known methods, and especially by VERADEL from Solvay Specialty Polymers, Inc. ® Available with PESU.

[0230] Polysulfone (PSU) refers to a polymer containing at least 50.0 mol.% of repeating units having the formula (K'-C):

[0231] (K'-C).

[0232] Preferably, at least 60.0 mol.%, or at least 70.0 mol.%, or at least 80.0 mol.%, or at least 90.0 mol.%, or at least 95.0 mol.%, or at least 99 mol.% of the repeating units in the PSU are repeating units (K'-C). Most preferably, all repeating units in the PSU are repeating units (K'-C).

[0233] PSU can be prepared by known methods and is available from Solvay Specialty Polymers, Inc. in the form of UDEL® PSU.

[0234] PPA

[0235] The PPA polymer is any polyamide wherein at least 50.0 mol%, preferably at least 75.0 mol%, and more preferably at least 99.0 mol% of repeating units (R) are present. PA The aromatic phthalic acid is selected from the group consisting of terephthalic acid, isophthalic acid, and combinations of the two phthalic acids, and at least one having the formula 2HN-R-NH2 (where R is C2-C). 18 The result of the condensation of (-alkylene) aliphatic diamines.

[0236] PPA is prepared by polycondensation of a diamine component containing all diamines and a diacid component containing all carboxylic acids at a temperature of at least 150°C.

[0237] use

[0238] As a second aspect, the present invention also relates to the use of expandable airbags made of or containing polymer compositions as defined herein for the preparation of thermoplastic composites (TPCs) by airbag inflation.

[0239] All embodiments and details relating to the PAI, airbag, or thermoplastic composite (TPC) disclosed above also apply to this use.

[0240] Polymer compositions (PCs) as defined herein can be used to prepare expandable airbags, which can be used to prepare thermoplastic composites according to the methods disclosed in US 11,572,644 B2 or US 2008 / 0251969.

[0241] As a third aspect, the present invention also relates to PAI as defined herein or precursors (P...) as defined herein. (This is for use in the preparation of expandable airbags as defined herein.)

[0242] As a fourth aspect, the present invention also relates to a method for preparing an expandable airbag. Experimental Section

[0243] Examples of the present invention illustrate the present invention.

[0244] Preparation of expandable airbags: In this work, polyetherimide (from Stratasys' Ultem1010 printing filament) was 3D printed using a Stratasys F900 3D printer to create a "scaffold". See also Figure 1 / 2 The support structure.

[0245] Then use Torlon ® 4000T (oligomeric precursor in NMP) coated scaffold. The PAI precursor has an acid value of approximately 80 mg KOH / g polymer.

[0246] Then Torlon ® 4000T was cured at 200°C to produce a tough and durable membrane (250 µm thick). The PEI of the scaffold was then dissolved in dichloromethane at room temperature to leave an expandable airbag made of PAI. See also Figure 2 / 2 .

Claims

1. A method for manufacturing a hollow composite material part made of or comprising a thermoplastic composite material (TPC) by airbag molding, the method comprising the step of placing a preform of the thermoplastic composite material (TPC) around an expandable airbag; wherein the thermoplastic composite material (TPC) comprises: ■ Polymer matrix (PM), which contains or is composed of the following: (i) at least one thermoplastic polymer; and (ii) optionally at least one plastic additive blended with the thermoplastic polymer; and ■ Continuous fibers embedded in the polymer matrix (PM); And wherein the airbag is made of or contains a polymer composition (PC) comprising, substantially consisting of, or consisting of: at least one polyamide-imide (PAI), optionally at least one filler, and optionally at least one polymer additive; Wherein PAI indicates that it contains at least 90.0 mol%, preferably more than 95.0 mol%, and preferably more than 99.0 mol% of repeating units (R). PAIa ) and (R PAIb The polymer, this ratio is based on the total number of repeating units of the PAI: (R PAIa ) (R PAIb ) Where Z is derived from substituted or unsubstituted C6-C. 20 The aromatic diamine has a divalent group, and wherein the molar ratio R = unit having an imide group / [unit having an imide group + unit having an acid and amide group] is at least 90.0 mol%, preferably at least 95.0 mol%.

2. The method of claim 1, wherein the method comprises the following steps: (1) Place the preform of the thermoplastic composite (TPC) that has been placed around the airbag in a mold, especially in a mandrel; (2) After the mold is closed, the airbag is inflated so as to compress the preform against the wall of the mold; (3) Apply heat to allow the polymer components of the polymer matrix (PM) to flow and solidify; (4) After cooling, the hollow composite material part is removed from the mold; (5) The airbag may be optionally removed from the formed hollow composite material component.

3. The method as described in claim 1 or 2, wherein, The preform comprises: (i) the thermoplastic polymer and (ii) the optional plastic additives and the continuous fibers.

4. The method as described in any of the preceding claims, wherein, The repeating unit (R) in this PAI PAIa ) and (R PAIb The total proportion is at least 95.0 mol%, preferably at least 99.0 mol%.

5. The method as described in any one of the preceding claims, wherein, Z can choose from the following groups: and combinations of two or more of the said groups, wherein Q 1 Is -O-, -S-, -C(O)-, -SO2, -SO-, -C y H 2y - where y is an integer from 1 to 5.

6. The method as described in any of the preceding claims, wherein, Z can choose from the following groups: , And combinations of two of the stated groups, wherein Q is -O-, -S-, -C(O)-, -SO2, -SO-, -C y H 2y - where y is an integer from 1 to 5.

7. The method of claim 5 or 6, wherein, Q is either -O- or -CH2-.

8. The method of claim 6, wherein, Z = , where Q = -CH2-.

9. The method of claim 5, wherein, These repeating units of the PAI are based on Z = where Q = -O-. and Z= The combination of .

10. The method according to any one of claims 1-4, wherein, These repeating units (R) PAIa Choose from the following groups: (him) (iia) (iiia) and combinations of two or more of the repeating units; and these repeating units (R) generated by the imidization of the above repeating units (ia)-(iiia). PAIb Choose from the following groups: (one)、 (iib) (iiib) And combinations of two or more of the repeating units.

11. The method as described in any of the preceding claims, wherein, The thermoplastic polymer is selected from the group consisting of: polyaryletherketone polymers (PAEK), polyphenylene sulfide polymers (PPS), polyamides—especially polyphthalamide (PPA), poly(arylether sulfone) polymers (PAES), polypropylene, polyethylene terephthalate (PET), polyetherimide (PEI), and combinations thereof, and more particularly wherein the thermoplastic polymer is polyaryletherketone (PAEK).

12. The method of claim 10 or 11, wherein, PAEK represents a polymer having ether and ketone bonds between its units, wherein these units conform to the formula -Q-Ar-, where Ar is a group selected from the group consisting of phenylene, biphenylene, or naphthylene, and Q is -O- or -C(=O)-, wherein each Q of one repeating unit is bonded to the Ar of another unit.

13. The method according to any one of claims 10-12, wherein, PAEK indicates the presence of more than 50.0 mol% repeating units (R). PAEK The polymers of which repeating units are selected from groups of units having formulas (JA) to (JQ): One of the units has an -O- or -C(=O)- group bonded to an aryl group of the other unit, and wherein: - R' j’ Each R' may be the same as or different from the others, and is selected from the group consisting of: halogens, alkyl, alkenyl, alkynyl, aryl, ethers, thioethers, carboxylic acids, esters, amides, imides, alkali metal or alkaline earth metal sulfonates, alkyl sulfonates, alkali metal or alkaline earth metal phosphonates, alkyl phosphonates, amines, and quaternary ammonium compounds; and - j' is zero or an integer in the range of 1 to 4.

14. The method as described in any of the preceding claims, wherein, The thermoplastic polymer is selected from the group consisting of: poly(ether ether ketone) (PEEK), poly(ether ketone ketone) (PEKK), poly(ether ketone) (PEK), poly(ether ether ketone ketone) (PEEKK), PEDEKK, PEEK-PEDEK, PEEK-PEoEK, and blends of two or more of the polymers, and more particularly from the group consisting of: PEEK, PEKK, and blends of two of the polymers.

15. The method as described in any of the preceding claims, wherein, The thermoplastic polymer or the thermoplastic polymer blend in the thermoplastic composite (TPC) is semi-crystalline or amorphous.

16. The method as described in any of the preceding claims, wherein, The thermoplastic polymer or the thermoplastic polymer blend in the thermoplastic composite (TPC) exhibits a heat of fusion (H₂O) of at least 5.0 J / g, more preferably at least 10.0 J / g or at least 15.0 J / g. f ), H f It is determined by DSC (Differential Scanning Calorimetry), especially according to ASTM D3418.

17. The method as described in any of the preceding claims, wherein, The thermoplastic polymer or the thermoplastic polymer blend in the thermoplastic composite (TPC) exhibits a melt temperature (Tm) of at least 200°C, preferably at least 260°C, and more preferably at least 300°C, which is determined by DSC (differential scanning calorimetry), and in particular according to ASTM D3418.

18. The method as described in any of the preceding claims, wherein: - The preform can be selected from the following groups: single-axis (1D), dual-axis (2D), 2.5D and triaxial (3D) types; - The preform is a woven preform containing fibers of a unidirectional material that has already been woven.

19. The method as described in any of the preceding claims, wherein, The thickness of the airbag is between 30.0 and 500.0 µm, preferably between 50.0 and 300.0 µm, and more preferably between 50.0 and 150.0 µm.

20. Use of an expandable airbag made of or comprising a polymeric composition (PC) for the preparation of hollow composite parts made of or comprising a thermoplastic composite material (TPC) by airbag inflation, wherein the polymeric composition (PC) comprises, substantially comprises, or comprises the following: The mixture comprises at least one polyamide-imide (PAI), optionally at least one filler, and optionally at least one polymer additive, wherein PAI represents a content of at least 90.0 mol%, preferably at least 95.0 mol%, and preferably at least 99.0 mol% of repeating units (R). PAIa ) and (R PAIb The polymer, this ratio is based on the total number of repeating units of the PAI: (R PAIa ) (R PAIb ) Where Z is substituted or unsubstituted C6-C. 20 The aromatic diamine has a divalent group, and wherein the molar ratio R = unit having an imide group / [unit having an imide group + unit having an acid and amide group] is at least 90.0 mol%, preferably at least 95.0 mol%.

21. The use as described in claim 20, wherein, Z is as defined in any one of claims 5-10.

22. The use as described in any one of claims 20-21, wherein, This thermoplastic composite (TPC) comprises: ■ A polymer matrix (PM) comprising or consisting of: (i) at least one thermoplastic polymer; and (ii) optionally at least one plastic additive blended with the thermoplastic polymer; and ■ Continuous fibers embedded in the polymer matrix (PM); The thermoplastic polymer is particularly as defined in any one of claims 10-14.

23. Polyamide-imide (PAI) or a precursor of PAI (P For use in the preparation of expandable airbags, the polyamide-imide (PAI) comprises at least 90.0 mol%, preferably more than 95.0 mol%, and more preferably more than 99.0 mol% of repeating units (R). PAIa ) and (R PAIb This ratio is based on the total number of repeating units in the PAI: (R PAIa ) (R PAIb ) Where Z is derived from substituted or unsubstituted C6-C. 20 The divalent group of an aromatic diamine, and characterized in that, The molar ratio R = units with imide groups / [units with imide groups + units with acid and amide groups] is at least 90.0 mol%, preferably at least 95.0 mol%; The precursor (P) It contains at least 90.0 mol%, preferably more than 95.0 mol%, and more preferably more than 99.0 mol% of repeating units (R). PAIa ) and (R PAIb ), and is characterized by a molar ratio R = The number of units having acid and amide groups / [units having imide groups + units having acid and amide groups] is at least 80.0 mol.

24. The use as described in claim 23, wherein, Z is as defined in any one of claims 5-10.

25. The use as described in claim 23 or claim 24, wherein: - The precursor (P) The number-average molecular weight M n Below 7,000 g / mol, advantageously between 1,000 and 7,000 g / mol, or between 2,000 and 5,000 g / mol; and / or - The precursor (P) The weight-average molecular weight M w Below 20,000 g / mol, preferably between 10,000 and 15,000 g / mol; M n and M w It was determined by size exclusion chromatography (SEC) in dimethylacetamide (DMAC) using polystyrene standards and a UV detector.

26. A method for preparing an expandable airbag, the expandable airbag being made of or comprising a polymer composition (PC), the polymer composition comprising, substantially comprising, or comprising of: At least one polyamide-imide (PAI), optionally at least one filler, and optionally at least one polymer additive (different from the filler); The method includes the following steps: #1: The precursor (P) containing polyamide-imide (PAI) A solution of the composition is coated onto a scaffold, which typically comprises or is made of a thermoplastic polymer; #2: Heating the coated support to which the composition has been applied; #3: Degrade or dissolve the scaffold in a suitable solvent; Among them, the precursor (P) The composition is in a solution in a polar solvent or a mixture of polar solvents, such as water and a mixture of polar solvents; Among them, the precursor (P) The PAI is a repeating unit (R) containing at least 90.0 mol%, preferably more than 95.0 mol%, and preferably more than 99.0 mol%. PAIa ) and (R PAIb The polymer, this ratio is based on the total number of repeating units of the PAI: (R PAIa ) (R PAIb ) Where Z is derived from substituted or unsubstituted C6-C. 20 The divalent group of an aromatic diamine, wherein: - For the precursor (P) ): Molar ratio R = Units with acid and amide groups / [Units with imide groups + Units with acid and amide groups] is indeed at least 80.0 mol%; - For this PAI: the molar ratio R = units with imide groups / [units with imide groups + units with acid and amide groups] is at least 90.0 mol%, preferably at least 95.0 mol%.

27. The method of claim 26, wherein, Z is as defined in any one of claims 5-10.

28. The method of claim 26 or 27, wherein, The thermoplastic polymer of the scaffold is selected from the group consisting of polyetherimide (PEI), polyethersulfone (PESU), poly(glycolic acid), and polyphenylsulfone (PPSU).

29. The method according to any one of claims 26-28, wherein, Step #2 involves heating at a temperature of at least 180°C.

30. The method according to any one of claims 26-29, wherein: - The precursor (P) The number-average molecular weight M n Below 7,000 g / mol, advantageously between 1,000 and 7,000 g / mol, or between 2,000 and 5,000 g / mol; and / or - The precursor (P) The weight-average molecular weight M w Below 20,000 g / mol, preferably between 10,000 and 15,000 g / mol; M n and M w It was determined by size exclusion chromatography (SEC) in dimethylacetamide (DMAC) using polystyrene standards and a UV detector.

31. The method according to any one of claims 26-30, wherein, The polar solvent is selected from the group consisting of: N-methyl-2-pyrrolidone (NMP), dimethylacetamide (DMAC), dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N-butylpyrrolidone, N-acetylpyrrolidone, methyl 5-(dimethylamino)-2-methyl-5-oxovalerate, dimethyldecylamide, 2-hydroxy-N,N-dimethylpropionamide, isosorbide dimethyl ether, 2-isobutyl-2-methyl-1,3-dioxolane-4-methanol, cyclopentanone, γ-valerol, a mixture comprising ethyl lactate and ethyl esters derived from soybean oil or corn oil, dimethyl glutarate, dimethyl succinate, dimethyl adipate, a mixture of dimethyl glutarate, dimethyl succinate, dimethyl adipate and 2-methyldimethyl glutarate; preferably, the polar solvent is NMP.

32. The method according to any one of claims 26-30, wherein, Precursor (P) It has an acid value of at least 50.0 mg KOH / g polymer as measured according to ASTM D664.

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