Silane-based adhesion primer deposited by atmospheric pressure plasma

Abstract

The invention relates to a method of bonding a polyamide substrate to a thermoplastic elastomer layer using an amine-silane-based adhesion primer deposited by atmospheric pressure plasma. It also relates to an article, such as a guide rail for guiding the movement of a movable window of a vehicle, comprising a polyamide substrate and a thermoplastic elastomer layer adhering to the substrate by means of an amine-silane-based adhesion primer, characterized in that the adhesion is achieved by such a method. Another object of the invention is glazing comprising such a guide rail, a movable window held within the guide rail, and optionally an element to which the guide rail is fixed.

Description

Title of the invention: Silane-based adhesion primer deposited by atmospheric pressure plasma

[0001] The invention relates to a method of adhesion between a polyamide substrate and a thermoplastic elastomer layer, using an amine-silane-based adhesion primer deposited by atmospheric pressure plasma. It also relates to an article, such as a guide rail for guiding the movement of a movable window of a vehicle, comprising a polyamide substrate and a thermoplastic elastomer layer adhering to the substrate by means of an amine-silane-based adhesion primer, characterized in that the adhesion is achieved by such a method. Another object of the invention is glazing comprising such a guide rail, a movable window held in the guide rail, and optionally an element to which the guide rail is fixed.

[0002] Thermoplastic elastomers, also called thermoplastic rubbers, are materials combining the elastic properties of elastomers and thermoplastic properties. Due to their chemical resistance, flexibility, and ability to recover after load application, these materials are used in numerous applications, particularly in the automotive field.

[0003] For some of these applications, the thermoplastic elastomer is deposited, via an injection molding step, onto a rigid substrate, such as a polyamide substrate. However, to obtain good adhesion properties between the flexible material and the rigid substrate, a simple cleaning, pickling, or etching step is insufficient, and a more significant modification of the substrate surface is necessary.

[0004] There are several techniques to address this problem, and one of them consists of applying a coating to the surface of the substrate, in particular by depositing a liquid solution containing an adhesive, classically based on isocyanate.

[0005] While good adhesion performance can be achieved with this method, it faces several limitations:

[0006] - the deposition of the liquid solution requires a drying step which lengthens the time implementation of the process;

[0007] - obtaining a homogeneous coating in thickness and surface area is difficult to reach ;

[0008] - the deposition of the thermoplastic elastomer after drying of the liquid solution must not to be too late, due to the sensitivity of the isocyanate-based coating to external conditions, such as cold and humidity;

[0009] - legislation is becoming increasingly strict regarding the use of isocyanates, which are toxic.

[0010] There therefore remains a real need to provide a process to overcome the above limitations, while maintaining good adhesion performance between the rigid substrate, typically polyamide, and the thermoplastic elastomer.

[0011] In this context, the inventors have developed a process in which a silane-based adhesion primer is deposited onto a polyamide substrate by atmospheric pressure plasma, prior to the deposition of a thermoplastic elastomer layer. Surprisingly, to obtain good adhesion performance, advantageously at least equivalent to that obtained with a liquid-deposited isocyanate-based primer, the silane must comprise at least one (O)n Si unit, where n is 1, 2, or 3, and at least one amine. Conversely, silanes lacking one or both of these characteristics do not allow good adhesion between the polyamide and the thermoplastic elastomer. This is particularly true of (3-glycidyloxypropyl)trimethoxysilane, which nevertheless contains an epoxy, a chemical function often found in commonly used adhesion primers.

[0012] Atmospheric pressure plasma also has the advantage of being cheaper and simpler to implement than low pressure (or "vacuum") plasma.

[0013] This invention finds its application particularly in the automotive field. In particular, guide rails, which guide the movement of a movable window of a vehicle when it is opened, are generally formed by the adhesion between a polyamide support and a thermoplastic elastomer strip.

[0014] Thus, the present invention relates to a method of adhesion between a polyamide substrate and a thermoplastic elastomer layer, comprising:

[0015] a) the deposition of an adhesion primer onto a surface of the polyamide substrate by an atmospheric pressure plasma comprising a silane, and

[0016] b) the deposition of a layer of thermoplastic elastomer on the adhesion primer,

[0017] characterized in that said silane comprises at least one (O)nSi motif, where n is 1, 2, or 3, and at least one amine.

[0018] In some embodiments, silane has the formula (I):

[0019] [Chem.l] Oh

[0020] in which:

[0021] - n is 1, 2, or 3 (preferably 2 or 3, even better n is 3),

[0022] - each R1, identical or different, represents a hydrocarbon group having 1 to 12 carbon atoms, possibly including one or more (for example, one or two) heteroatoms,

[0023] - each R2, identical or different, represents a hydrocarbon group having 1 to 12 carbon atoms, and

[0024] - R3 represents a hydrocarbon group having 1 to 12 carbon atoms, comprising one or more (for example, one, two or three) groups chosen from -NH2 and -NH-, and possibly one or more (for example, one, two or three) additional heteroatoms.

[0025] In some embodiments, n is 3, each R1, identical or different, is an alkyl in Cl-Cl 2, and R3 has the formula -R4-NH2 where R4 is an alkylene in Cl-Cl 2 or a heteroalkylene in Cl-Cl 2.

[0026] Preferably, the silane is (3-aminopropyl)triethoxysilane, (3-aminopropyl)trimethoxysilane or a mixture thereof.

[0027] In some embodiments, the thermoplastic elastomer is a mixture based on polypropylene and a polystyrene-b-poly(ethylene-butylene)-b-polystyrene copolymer, or a mixture based on polypropylene and ethylene-propylene-diene rubber.

[0028] In some embodiments, the substrate is made of polyamide 6 or polyamide 6-6, and optionally includes glass beads or fibers.

[0029] In some embodiments, the plasma is a plasma of N2, O2, air, argon, helium, or a combination thereof, preferably an air or N2 plasma, even better an air plasma.

[0030] In some embodiments, the power of the plasma is between 600 W and 1500 W, preferably between 650 W and 1200 W.

[0031] In certain embodiments, the plasma comprising said silane is ejected by a torch moving at a speed of 20 to 600 mm / sec, for example from 20 to 100 mm / sec, in step a). In such an embodiment, 1 to 10 track passes, for example 3 to 7 track passes, can be implemented.

[0032] The projection distance between the torch and the surface of the substrate is advantageously between 1 cm and 10 cm, for example between 1.5 cm and 4 cm, in step a).

[0033] In some embodiments, silane is introduced into the plasma at a flow rate of between 10 and 300 pL / min.

[0034] In some embodiments, the thermoplastic elastomer is deposited, in step b), by injection overmolding.

[0035] Another object of the present invention is an article, such as a guide rail intended to guide the movement of a movable window of a vehicle, comprising:

[0036] - a polyamide substrate and

[0037] - a layer of thermoplastic elastomer adhering to the substrate by means of a primary adhesion based on a silane comprising at least one (O)nSi motif, where n is 1, 2, or 3, and at least one amine,

[0038] characterized in that adhesion by means of said primary is obtained by the process as defined in this application.

[0039] Another object of the present invention is a glazing comprising a guide rail as defined above, a movable pane of glass received in the guide rail, and optionally an element on which the guide rail is fixed. FIGURES

[0040] [Fig.l]: Displacement pattern of a plasma device during step a) of the adhesion process, in a particular mode of the invention.

[0041] [Fig.2]: Exploded view of a guide rail and a movable window, in a mode by particular of the invention.

[0042] [Fig.3]: Schematic cross-sectional representation of a guide rail, in a particular mode of the invention.

[0043] [Fig.4]: Exploded view of a glazing, in a particular mode of the invention.

[0044] [Fig. 5]: Schematic cross-sectional representation of a glazing unit, in a particular mode of the invention. DETAILED DESCRIPTION OF THE INVENTION

[0045] Definitions

[0046] The groups mentioned in this application with a prefix Cx-Cy, where x and y are integers, have from x to y carbon atoms. If, for example, the term Ci-C6 is used, this means that the corresponding group can comprise from 1 to 6 carbon atoms, in particular 1, 2, 3, 4, 5 or 6 carbon atoms.

[0047] By "aliphatic" is meant a non-aromatic acyclic hydrocarbon group, saturated or unsaturated, and linear or branched. In a particular mode, an aliphatic group is an alkyl or alkenyl group.

[0048] By "alkyl," we mean a saturated aliphatic group, preferably having from 1 to 12 carbon atoms. Examples of Cl-Cl2 alkyls include, in particular, a methyl, an ethyl, a propyl, an isopropyl, a butyl, a pentyl, a hexyl, a heptyl, an octyl, a nonyl, a decyl, an undecyl, and a dodecyl.

[0049] By "alkenyl" is meant an unsaturated aliphatic group, comprising at least one carbon-carbon double bond, preferably having from 2 to 12 carbon atoms. Examples of C2-C12 alkenyls include, in particular, ethenyl, propenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, and dodecenyl.

[0050] By "alicyclic" is meant a non-aromatic cyclic hydrocarbon group (mono- or polycyclic), saturated or unsaturated. In a particular mode, an alicyclic group is a cycloalkyl group.

[0051] By "cycloalkyl" is meant a saturated alicyclic group, preferably having from 3 to 12 carbon atoms. Examples of C3-C12 cycloalkyls include, in particular, a cyclopropyl, a cyclopentyl, a cyclohexyl, a cycloheptyl, a cyclooctyl, or a cyclododecyl.

[0052] By "aryl" is meant an aromatic hydrocarbon group (mono- or polycyclic), preferably having from 6 to 12 carbon atoms. An example of a C6-C12 aryl is phenyl.

[0053] By "alkylene" is meant a saturated divalent hydrocarbon group, linear or branched, preferably having from 1 to 12 carbon atoms. Examples of alkylene include methylene (-CH2-), ethylene (-(CH2)2-), propylene (-(CH2)3-), butylene (-(CH2)4-), pentylene (-(CH2)5-), or hexylene (-(CH2)6-).

[0054] A “heteroalkylene” group is an alkylene group comprising one or more heteroatoms.

[0055] By "a group comprising at least one heteroatom", we mean a group interrupted by, or comprising at one and / or the other of its extremities, at least one heteroatom.

[0056] In this application, the expression "at least one" may be used equivalently to "one or more".

[0057] In the present application, a range defined with the expression "between (X) and (Y)" includes the lower bound (X) and upper bound (Y), and is equivalent to "from (X) to (Y)".

[0058] The method according to the invention is a simple and effective method that enables good adhesion between a polyamide substrate and a thermoplastic elastomer layer. It is based on the deposition onto the substrate of a silane-based adhesion primer by atmospheric pressure plasma, which silane comprises at least one (O)nSi unit, where n is 1, 2, or 3, and at least one amine.

[0059] In step a) of the process according to the invention, an adhesion primer is deposited onto a surface of the polyamide substrate by an atmospheric pressure plasma comprising a silane, said silane comprising at least one (O)nSi unit, where n is 1, 2, or 3, and at least one amine. This type of deposition may be called plasma-enhanced chemical vapor deposition (or PE-CVD).

[0060] The term "silane" refers to an organic compound comprising one or more silicon atoms. The silane used in the process of the invention is such that at least one silicon atom forms an (O)nSi motif, where n is 1, 2, or 3. The oxygen(s) of the (O)nSi motif are typically bonded to a hydrocarbon group, forming in this case an (RO)nSi- motif where n is 1, 2, or 3, and each R, whether identical or different, represents a hydrocarbon group. The silane further comprises at least one amine (for example, one or two amines), said at least one amine being selected, in particular, from an -NH2 group and an -NH- group. Preferably, the silane comprises a -NH2 group, and possibly one or more (for example one, two, three or four, preferably only one) -NH- groups.

[0061] Preferably, said silane comprises an (O)nSi motif, where n is 1, 2, or 3, an NH2 group, and optionally one or more (for example, one, two, three, or four, preferably only one) -NH- groups. Better still, said silane comprises an (O)3Si motif and an NH2 group.

[0062] Said at least one (O)nSi motif, where n is 1, 2, or 3, and said at least one amine are typically linked together by a hydrocarbon group.

[0063] Said silane generally has between 3 and 70 carbon atoms. Said silane generally has a molar mass between 100 and 600 g / mol, for example between 150 and 500 g / mol.

[0064] Preferably, n is 2 or 3, better still n is 3.

[0065] In a particular embodiment, said silane has the formula (I):

[0066] [Chem.2]

[0067] in which:

[0068] - n is equal to 1, 2, or 3 (preferably 2 or 3, even better n is equal to 3),

[0069] - each R1, identical or different, represents a hydrocarbon group having 1 to 12 carbon atoms, possibly including one or more (for example, one or two) heteroatoms,

[0070] - each R2, identical or different, represents a hydrocarbon group having 1 to 12 carbon atoms, and

[0071] - R3 represents a hydrocarbon group having 1 to 12 carbon atoms, comprising one or more (for example, one, two or three) groups chosen from -NH2 and -NH-, and possibly one or more additional heteroatoms.

[0072] When n is 1, 2 or 3, the compound of formula (I) can be represented respectively as follows:

[0073] [Chem.3] om qr= om t î i i 1 1 Yes, yes, yes. R2 R2 Oæ (n=1), (n=2); (n=3).

[0074] A hydrocarbon group can be linear or branched, cyclic or acyclic, saturated or unsaturated, aliphatic or aromatic.

[0075] In a particular embodiment, each R1, identical or different, represents an aliphatic group in C1-C12, an alicyclic group in C3-C12 or an aryl in C6-C12. In a more particular embodiment, each R1, identical or different, represents an alkyl in Cl-Cl 2, an alkenyl in C2-C12, a cycloalkyl in C3-C12 or an aryl in C6-C12.

[0076] In a particular mode, R1 is a C1-C12 alkyl, possibly comprising one or more oxygens.

[0077] Preferably, each R1, identical or different (preferably identical), represents a Cl-Cl2 alkyl. More preferably, each R1, identical or different (preferably identical), represents a C1-C6 alkyl, for example a methyl or an ethyl.

[0078] When present (i.e., if n is 1 or 2), each R2, whether identical or different, may represent a C1-C12 aliphatic group, a C3-C12 alicyclic group, or a C6-C12 aryl group. More particularly, each R2, whether identical or different, may represent a C1-C12 alkyl group, a C2-C12 alkenyl group, a C3-C12 cycloalkyl group, or a C6-C12 aryl group. Preferably, each R2, whether identical or different, represents a C1-C12 alkyl group. Even more preferably, each R2, whether identical or different, represents a C1-C6 alkyl group, for example, a methyl or an ethyl group.

[0079] In a particular embodiment, R3 represents an alkyl having 1 to 12 carbon atoms, comprising one or more (for example, one, two or three) groups selected from -NH2 and -NH-, and optionally one or more (for example, one, two or three) additional heteroatoms (selected in particular from oxygen and sulfur).

[0080] In a preferred embodiment, R3 is a group of formula -R4-NH2, in which R4 represents a divalent hydrocarbon group having 1 to 12 carbon atoms, optionally comprising one or more heteroatoms.

[0081] In a particular embodiment, R4 represents a divalent hydrocarbon group having 1 to 12 carbon atoms, optionally comprising one or more (for example, one, two, three or four) heteroatoms selected from oxygen, nitrogen and sulfur.

[0082] Preferably, R4 is a Cl-Cl2 alkylene or a Cl-Cl2 heteroalkylene. In this mode, the C1-C12 heteroalkylene may comprise, for example, one, two, three, or four heterotomes, in particular one, two, three, or four nitrogen atoms.

[0083] More preferably, R4 is a C1-C6 alkylene, for example a propylene (i.e. -CH2-CH2-CH2-).

[0084] In a preferred mode, n is 3, each R1, identical or different, is an alkyl in Cl-Cl 2, and R3 is of formula -R4-NH2 where R4 is an alkylene in Cl-Cl 2 or a heteroalkylene in Cl-Cl 2.

[0085] Preferably, said silane is (3-aminopropyl)triethoxysilane, the (3-aminopropyl)trimethoxysilane or a mixture thereof.

[0086] By "polyamide" is meant a condensation product of one or more amino acids, of condensation of one or more lactams, or of condensation of one or more polyacids (e.g. diacids) with one or more polyamines (e.g. diamines).

[0087] Examples of amino acids include amino-caproic acid, amino-7-heptanoic acid, amino-11-undecanoic acid, amino-12-dodecanoic acid or a salt thereof.

[0088] Examples of lactams include [3,[3-dimethylpropriolactam, α,α-dimethylpropriolactam, amylolactam, capryllactam, caprolactam or lauryllactam.

[0089] Examples of diacids include isophthalic acid, terephthalic acid, succinic acid, adipic acid, azelaic acid, suberic acid, sebacic acid, dodecanedicarboxylic acid, 1,4-cyclohexyldicarboxylic acid, or a salt of these.

[0090] Examples of diamines include aliphatic diamines or aryl diamines. More specific examples include rhexamethylenediamine, piperazine, tetramethylenediamine, roctamethylenediamine, decamethylenediamine, 1,5-diaminohexane, 2,2,4-trimethyl-1,6-diaminohexane, diamine polyols, isophoronediamine, methyl pentamethylenediamine, bis(aminocyclohexyl)methane, bis(3-methyl-4-aminocyclohexyl)methane, dodecamethylenediamine, metaxylyenediamine, bis-p-aminocyclohexylmethane and trimethylhexamethylenediamine or a salt thereof.

[0091] The polyamide can be a homopolyamide or a copolyamide.

[0092] Examples of homopolyamides include polyamide 6 (also called polycaprolactam, denoted PA 6) or polyamide 6-6 (i.e., adipic acid and hexamethylenediamine polymer, denoted PA 6-6).

[0093] Examples of copolyamides include copolymers of caprolactam and lauryllactam (PA 6 / 12), copolymers of caprolactam, adipic acid and hexamethylenediamine (PA 6 / 6-6), copolymers of caprolactam, lauryllactam, adipic acid and hexamethylenediamine (PA 6 / 12 / 6-6), copolymers of caprolactam, lauryllactam, 11-aminoundecanoic acid, azelaic acid and hexamethylenediamine (PA 6 / 6-9 / 11 / 12), and copolymers of caprolactam, lauryllactam, 11-aminoundecanoic acid, adipic acid and hexamethylenediamine (PA 6 / 6-6 / 11 / 12), copolymers of lauryllactam, azelaic acid and hexamethylene diamine (PA 6-9 / 12).

[0094] In a particular mode, the polyamide is a polyamide 6 or a polyamide 6-6.

[0095] Preferably, the polyamide is a polyamide 6.

[0096] The substrate may further comprise fillers such as beads or fibers of Reinforcement, including glass beads, glass fibers, carbon fibers, or poly(p-phenylene terephthalamide) fibers (Kevlar®). These fillers are typically dispersed homogeneously within the polyamide. For example, the substrate may contain between 5% and 60% (e.g., between 20% and 50%, between 30% and 50%, between 35% and 45%, or between 38% and 42%) by mass of fillers (e.g., glass beads or fibers), relative to the total weight of the substrate.

[0097] In a preferred embodiment, the substrate is made of polyamide 6 or polyamide 6-6 (preferably polyamide 6), and comprises glass fibers, typically between 30% and 50% by weight relative to the total weight of the substrate.

[0098] The plasma used in the process of the invention is an atmospheric pressure plasma. Atmospheric pressure plasma, as opposed to low-pressure plasma, refers to a plasma well known to those skilled in the art, which is operated at a pressure on the order of atmospheric pressure. This pressure can typically be 1000 ± 400 mbar, preferably 1000 ± 200 mbar, or even 1000 ± 100 mbar.

[0099] Plasma is formed from a gas subjected to an electrical discharge. Devices suitable for forming atmospheric pressure plasma are well known to those skilled in the art. Generally, such a device comprises a chamber containing a pair of electrodes and opening onto a nozzle. In such a device, the gas passes through the pair of electrodes, which generate the electrical discharge, and the plasma initiated at these electrodes is ejected through the nozzle. The device is typically a plasma torch.

[0100] In a particular embodiment, the plasma is a plasma of a gas selected from N2, O2, air, argon, helium, and a combination thereof. In some embodiments, said gas is selected from the aforementioned gases and further comprises dihydrogen, in a content less than or equal to 5% by volume.

[0101] Preferably, the plasma is an air or N2 plasma, even better an air plasma.

[0102] The power of the plasma is advantageously between 600 W and 1500 W, for example between 600 W and 1300 W, preferably between 650 W and 1200 W, or even between 700 W and 1200 W.

[0103] The flow rate of the gas used to form the plasma can, for example, be between 10 and 100 L / min, preferably between 30 and 50 L / min, or even between 35 and 45 L / min.

[0104] The silane is preferably introduced into the plasma by spraying. Advantageously, when the plasma is ejected from a nozzle, the silane is introduced into the plasma after its ejection from the nozzle. Said silane is generally introduced into the plasma continuously as the latter is applied to the surface of the substrate. The flow rate at which the silane is introduced into the plasma can, for example, be between 10 pL / min and 300 pL / min, preferably between 50 pL / min and 250 pL / min, or even between 150 pL and 250 pL / min. It is preferable to use an inert gas, such as N2 or argon, to introduce the silane into the plasma by spraying.

[0105] Preferably, the silane is introduced into the plasma in the form of an undiluted liquid. By "undiluted liquid" is meant a liquid consisting essentially of silane (that is to say, typically comprising at least 90%, or even at least 95%, or even at least 98%, by weight of said silane relative to the total weight of the liquid).

[0106] In certain embodiments, the plasma comprising said silane is ejected by a device (typically a torch) moving at a speed of 20 to 600 mm / sec, for example, 20 to 100 mm / sec (or even 20 to 50 mm / sec) or 50 to 400 mm / sec (or even 100 to 400 mm / sec). In such an embodiment, 1 to 10 track passes, for example, 3 to 7 track passes, can be implemented. When several track passes are implemented, the device's movement is advantageously carried out according to a pattern substantially identical to the previous one. The pattern determined by the device's movement is not limiting.

[0107] The projection distance between the device (typically a torch) and the substrate surface is advantageously between 1 cm and 10 cm, for example between 1.5 cm and 4 cm. As explained above, the device (for example, a torch) generally includes a nozzle (or any other equivalent type of orifice), and the projection distance then corresponds to the distance between the nozzle through which the plasma is ejected and the substrate surface subjected to the plasma.

[0108] The thickness of the adhesion primer layer is generally between 10 nm and 100 pm, more particularly between 1 pm and 50 pm. The thickness of the polyamide substrate is generally between 1 and 20 mm, for example between 1 and 10 mm, or even between 2 and 6 mm. The thickness of the thermoplastic elastomer layer is generally between 1 and 20 mm, for example between 1 and 10 mm, or even between 2 and 6 mm.

[0109] In a particular embodiment, the polyamide substrate has a width of between 5 and 20 mm (for example, between 8 and 20 mm) and a length of between 200 and 600 mm. In a particular embodiment, the polyamide substrate has a total surface area of ​​between 20 and 500 cm².

[0110] In certain embodiments, the substrate comprises two faces (preferably each having a surface area of ​​between 10 and 150 cm2). In such an embodiment, the adhesion primer is advantageously deposited on only one face, and preferably covers, after its deposition, at least 70%, or even at least 80%, or at least 90%, or even at least 95% of said single face.

[0111] Alternatively, the adhesion primer can be deposited on both sides, and preferably covers, after its deposition, at least 70%, or even at least 80%, or even at least 90%, or even at least 95% of each side.

[0112] In the process according to the invention, step b) includes the deposition of a layer of thermoplastic elastomer on the adhesion primer.

[0113] The term "thermoplastic elastomer" (or "TPE") means a copolymer (typically block-type) or polymer blend that combines the elastic properties of an elastomer with thermoplastic characteristics. A thermoplastic elastomer is generally a copolymer (typically block-type), a polymer blend, or a combination thereof, typically based on one or more elastomers and one or more thermoplastic polymers. Thermoplastic elastomers are a class of materials well known to those skilled in the art.

[0114] In a particular embodiment, the thermoplastic elastomer is a block copolymer. In such an embodiment, the copolymer preferably comprises at least one thermoplastic block selected from a polyurethane block, a polystyrene block, a polyester block, a poly(methyl methacrylate) block and a polyamide block, and at least one elastomer block selected from a polyether block, a polybutadiene block, a polyisoprene block, a polyethylene block, a poly(ethylene-propylene) block, and a poly(ethylene-butylene) block.

[0115] In a more particular embodiment, the thermoplastic elastomer is a block copolymer of polyurethane and polybutadiene, polyurethane and polyether, polyester and polybutadiene, polyester and polyether, polyamide and polybutadiene, polyamide and polyether, polystyrene and polybutadiene, polystyrene and polyisoprene, polystyrene and poly(ethylene-butylene), polystyrene and poly(ethylene-propylene), polystyrene and poly(ethylene-ethylene / propylene), or a combination thereof.

[0116] Particular examples of TPEs include: polystyrene-b-polybutadiene-b-polystyrene (SBS), polystyrene-b-polyisoprene-b-polystyrene (SIS), polystyrene-b-poly(ethylene-butylene)-b-polystyrene (SEBS), polystyrene-b-poly(ethylene-propylene)-b-polystyrene (SEPS), polystyrene-b-poly(ethylene-ethylene / propylene)-b-polystyrene (SEEPS), poly(methyl methacrylate)-b-polybutadiene-b-polystyrene (MBS), or a mixture of these.

[0117] In another particular embodiment, the thermoplastic elastomer is a mixture of polymers. Examples of such TPEs include a mixture based on polypropylene and a polystyrene-β-poly(ethylene-butylene)-β-polystyrene (SEBS) copolymer, or a mixture based on polypropylene and rubber (such as ethylene-propylene-diene rubber (EPDM), where the diene may, in particular, be ethylidene norbomene (ENB), styrene-butadiene rubber (SBR), or acrylonitrile butadiene rubber (NBR), preferably rubber (EPDM). The rubber may or may not be vulcanized.

[0118] In a particular mode, the thermoplastic elastomer is a mixture based on po- lypropylene and a polystyrene-b-poly(ethylene-butylene)-b-poly styrene copolymer, or a mixture based on polypropylene and ethylene-propylene-diene rubber.

[0119] Preferably, the thermoplastic elastomer is deposited by injection overmolding. In this method, the thermoplastic elastomer is typically fed into a heat press, generally in the form of granules, beads, or pellets, to be heated prior to its deposition onto the adhesion primer. The temperature to which the thermoplastic elastomer is heated is sufficient for it to melt. Preferably, the temperature to which the thermoplastic elastomer is heated prior to deposition is between 180°C and 260°C, for example, between 200°C and 250°C, or even between 210°C and 230°C. Once heated, the thermoplastic elastomer is deposited onto the adhesion primer. In injection overmolding, a mold is used to define the shape of the thermoplastic elastomer layer deposited on the adhesion primer.

[0120] Preferably, the thermoplastic elastomer covers at least 90%, or even at least 95%, and more preferably at least 98% of the surface area of ​​the adhesion primer. In some embodiments, the thermoplastic elastomer covers 100% of the surface area of ​​the adhesion primer.

[0121] The process according to the invention makes it possible to obtain excellent adhesion between the polyamide substrate and the thermoplastic elastomer layer. Advantageously, the peel strength, obtained by a peel test with a peel angle of 90° and a speed of 100 mm / min, at 23 °C and 50% relative humidity, is at least 30 N / cm, for example between 30 N / cm and 50 N / cm, preferably with a cohesion rate of at least 20%, or at least 30%, or even at least 50% and better still at least 70%.

[0122] The present invention also relates to an article comprising:

[0123] - a polyamide substrate and

[0124] - a layer of thermoplastic elastomer adhering to the substrate by means of a primary adhesion based on a silane comprising at least one (O)nSi motif where n is 1, 2, or 3, and at least one amine,

[0125] characterized in that adhesion by means of the primary is obtained by the process as defined in this application.

[0126] It is understood that the definitions and methods described above for the process (e.g. polyamide, silane, thermoplastic elastomer, plasma conditions, dimensions) also apply to the article according to the invention.

[0127] The article according to the invention may, for example, be an article used in the automotive field.

[0128] Such an article may in particular be a filler insert, a fixing insert (e.g. a filler or fixing insert for the bodywork), and / or a positioning insert (e.g. a pin). More specifically, the item may be a guide rail intended to guide the movement of a vehicle window.

[0129] Fig. 2 shows an example (exploded view) of a guide rail 1 configured to guide the movement of a movable window 3 of a vehicle, in a direction indicated by a double arrow on Fig. 2.

[0130] Figure 3 shows a cross-section of an example of a guide rail 1. The cross-section of the guide rail 1 has a general U-shape. The guide rail 1 comprises a polyamide substrate 4, which forms an outer part of the guide rail 1, and a thermoplastic elastomer layer 6, which forms an inner part of the guide rail 1. The substrate 4 acts as a rigid support and surrounds the flexible thermoplastic elastomer layer 6. The thermoplastic elastomer layer 6 adheres to the substrate 4 by means of a layer 5 (shown as a dashed line in the figure) of a silane-based adhesion primer comprising at least one (O)nSi unit (where n is 1, 2, or 3) and at least one amine, and the adhesion by means of the primer is achieved by the process as defined in this application. The internal surface 6i of the thermoplastic elastomer layer 6 defines a housing configured to receive an edge of a movable window and guide its movement.The external surface 4i of the substrate 4 is configured to be attached to a vehicle component, such as a body panel or a fixed window (e.g., a quarter window). The external surface 4i of the substrate 4 may, in particular, define a housing configured to receive the edge of a fixed window.

[0131] Another object of the present invention is glazing comprising a guide rail as defined above, a movable pane of glass held in the guide rail, and optionally an element to which the guide rail is fixed. This element may be a body panel of a vehicle, or a fixed pane of glass, such as a quarter window. Preferably, this element is a fixed pane of glass, such as a quarter window.

[0132] Figure 4 shows an example (exploded view) of glazing 10, which includes a guide rail 1 and a movable pane of glass 3 held in the guide rail 1, in which the guide rail 1 is fixed to an element 2 which is a fixed pane of glass. The guide rail may in particular be as described above for Figure 3.

[0133] Figure 5 shows a cross-section of an example of glazing 10 comprising a guide rail 1 as described above for Figure 3, a movable pane of glass 3 whose edge is received in the recess defined by the inner surface 6i of the thermoplastic elastomer layer 6 of the guide rail 1, and in which the guide rail 1 is fixed to an element 2 which is a fixed pane of glass. More particularly, the outer surface 4i of the substrate 4 of the guide rail 1 defines a recess which receives the edge of the fixed pane of glass. EXAMPLES

[0134] General Procedure

[0135] The substrate (hereinafter referred to as "PA") tested here is made of polyamide 6 and contains 40% glass fibers for reinforcement. The sample is cut to the following dimensions: 15 cm x 4 cm and has a thickness of 4 mm.

[0136] The thermoplastic elastomer (hereinafter referred to as "TPE") is in the form of pellets approximately 3 mm in diameter. The PA substrate and the TPE are stored overnight at 80°C to eliminate any moisture.

[0137] Just before plasma functionalization, the PA substrates are cleaned with MEK solvent (methyl ethyl ketone = butanone CAS 78-93-3). The PA substrates are then fixed with aluminum adhesive to a glass sheet under the plasma torch for functionalization. The silane is nebulized by a carrier gas (here nitrogen) and sprayed just below the torch nozzle from which the plasma is ejected (a technique known as PE-CVD).

[0138] The torch is moved according to a pattern shown in [Fig. 1], to functionalize one face of the substrate. A complete movement along this pattern is called "a track", and can be performed once or several times.

[0139] The thickness of the adhesion primer layer is approximately 10-20 pm.

[0140] Several conditions were tested in the following range:

[0141] - Plasma power: from 650 W to 1200 W,

[0142] -the distance between the torch and the PA substrate: between 1.9 cm and 3.9 cm,

[0143] - the number of tracks: from 1 to 10,

[0144] - speed: from 20 to 100 mm / s,

[0145] -the plasma gas: air or pure nitrogen,

[0146] -the silane flow rate in the range of 0 to 300 pL / min.

[0147] Silane is sprayed in liquid form (purity: 99%), and is stored refrigerated manager.

[0148] TPE pellets are incorporated into a manual hot press and heated at 220°C. A mold is prepared to mold the TPE strip onto the PA (TPE strip size: 15 cm x 4 cm and 3 mm thick). The TPE is then injected into the mold. The typical time between functionalization and molding varies between 2 and 3 hours. Samples are stored at 50% relative humidity (RH) and 23°C, then subjected to a peel test (peel angle = 90°; speed = 100 mm / min; temperature = 23°C and RH = 50%). The time between sample preparation and the peel test is 7 days. The cohesion level is assessed visually.

[0149] Results of coat tests

[0150] [Chem.4] / APTMS SUITABLE toCHs HgC 0.5 HsC-Si-IHHCHg CHs CHs

[0151] [Tables 1] TEOS GPTMS HMDS Plasma + Silane APPTES Power (W) Silane Flow Rate (pl / min) Distance (cm) Tracks Gas Velocity (mm / sec) Peel Force (N / cm) % Cohesion 650-1200 200 1.9-2.9 4-5 Air 20-100 37-40 60-90

[0152] [Tables2] Plasma + Silane APTMS Power (W) Silane Flow Rate (pl / min) Distance (cm) Tracks Gas Velocity (mm / sec) Peel Force (N / cm) % Cohesion 650-1200 200 2.9-3.9 4-5 air or n2 20-100 33-42 40-91

[0153] Comparative examples:

[0154] [Tables3] Treatment Coat Strength (N / cm) % Primary Cohesion Isocyanate1 40 90% No treatment2 <5 0% Plasma only3 <5 0% Silan only4 (silanes tested: TEOS, HMDS, APTMS, APTES, GPTMS) <5 0% Plasma + silane TEOS5 <5 0% Plasma + silane GPTMS6 <10 0% Plasma + silane HDMS7 <20 0%

[0155] 1 - Application of an isocyanate primer (62% (w / w) of Kôratac GM 503 - Kommerling; 5% (w / w) of Kôracur TH 240 - Kommerling; 33% (w / w) of MEK) on the PA, then drying at 80°C for 30 minutes, then deposition of the TPE.

[0156] 2 - PA-TPE adhesion without treatment (i.e., only washing of the PA with MEK) before TPE filing).

[0157] 3 - The plasma jet is applied to the PA (activation at 900 W, 5 tracks, 100 mm / s, air plasma, distance = 1.6cm) but without silane, then TPE deposition.

[0158] 4 - a 0.3 mL solution of silane (TEOS, HMDS, APTMS, APTES, or GPTMS) diluted in 1 mL of HCl (0.1M) and 9 mL of isopropanol is stirred at room temperature for 1 hour to allow hydrolysis of silane, and wet-applied to the PA, without plasma, then TPE application.

[0159] 5 - General procedure described above in which the silane used is TEOS (Plasma power: 700-1200 W, silane flow rate: 200pL / min, projection distance: 2.9 cm, number of tracks: 5, plasma gas: air, travel speed: 20-100 mm / sec).

[0160] 6 - General procedure described above in which the silane used is GPTMS (Plasma power: 700-1200 W, silane flow rate: 200pL / min, projection distance: 2.9 cm, number of tracks: 5, plasma gas: air, travel speed: 20-100 mm / sec).

[0161] 7 - General procedure described above in which the silane used is HDMS (Plasma power: 650-1200 W, silane flow rate: 200pL / min, projection distance: 2.9 cm, number of tracks: 5-10, plasma gas: air, travel speed: 100 mm / sec).

[0162] The results in Tables 1-3 show that:

[0163] - the presence of an (O)nSi motif (specifically here (O)3Si) and an amine in the silane is crucial for obtaining good adhesion properties. Indeed, a silane containing only the (O)nSi motif (TEOS, GPTMS) or a silane containing only an amine (HMDS) does not yield good results.

[0164] - the peeling forces obtained with plasma comprising a silane comprising at at least one (O)nSi motif and at least one amine are equivalent, and sometimes better, than those obtained by application of the isocyanate primary (Table 1 vs. Table 3 “isocyanate primary”). Very satisfactory cohesion rates, often equivalent to those obtained by application of the isocyanate primary, have also been achieved.

[0165] - whatever the conditions (power, flow rate, nature of the gas...) which have been ap When applied, good adhesion performance was achieved, demonstrating the flexibility of the system (Table 1).

Claims

Demands

1. A method for adhesion between a polyamide substrate and a thermoplastic elastomer layer, comprising: a) the deposition of an adhesion primer on a surface of the polyamide substrate by an atmospheric pressure plasma comprising a silane, and b) the deposition of a thermoplastic elastomer layer on the adhesion primer, characterized in that said silane comprises at least one (O)nSi motif, where n is 1, 2, or 3, and at least one amine.

2. Process according to claim 1, wherein the silane is of formula (I): [Chem. 5] (Th in which: - n is 1, 2, or 3, - each R1, identical or different, represents a hydrocarbon group having 1 to 12 carbon atoms, optionally comprising one or more heteroatoms, - each R2, identical or different, represents a hydrocarbon group having 1 to 12 carbon atoms, and - R3 represents a hydrocarbon group having 1 to 12 carbon atoms, comprising one or more groups selected from -NH2 and -NH-, and optionally one or more additional heteroatoms.

3. Method according to claim 2, wherein n is 3, each R1, identical or different, is a C1-C12 alkyl, and R3 is of formula -R4-NH2 where R4 is a Cl-Cl2 alkylene or a Cl-Cl2 heteroalkylene.

4. A method according to claim 2 or 3, wherein the silane is (3-aminopropyl)triethoxysilane, (3-aminopropyl)trimethoxysilane or a mixture thereof.

5. A method according to any one of claims 1 to 4, wherein the thermoplastic elastomer is a mixture based on polypropylene and a polystyrene-b-poly(ethylene-butylene)-b-polystyrene copolymer, or a mixture based on polypropylene and ethylene-propylene-diene rubber.

6. A method according to any one of claims 1 to 5, wherein the substrate is made of polyamide 6 or polyamide 6-6, and may include glass beads or fibers.

7. A method according to any one of claims 1 to 6, wherein the plasma is a plasma of N2, O2, air, argon, helium, or a combination thereof, preferably an air or N2 plasma, even better an air plasma.

8. A method according to any one of claims 1 to 7, wherein the plasma power is between 600 W and 1500 W, preferably between 650 W and 1200 W.

9. A method according to any one of claims 1 to 8, wherein the plasma comprising said silane is ejected by a torch moving at a speed of 20 to 600 mm / sec, for example 20 to 100 mm / sec, at step n A

10. aj. Method according to claim 9, wherein 1 to 10 track passes, for example 3 to 7 track passes are carried out in step a).

11. A method according to claim 9 or 10, wherein the projection distance between the torch and the surface of the substrate is between 1 cm and 10 cm, for example between 1.5 cm and 4 cm, in step a).

12. A method according to any one of claims 1 to 11, wherein silane is introduced into the plasma at a flow rate of between 10 and 300 pL / min.

13. A method according to any one of claims 1 to 12, wherein the thermoplastic elastomer is deposited, in step b), by injection overmolding.

14. Article, such as a guide rail (1) for guiding the movement of a movable window (3) of a vehicle, comprising: - a polyamide substrate (4) and - a thermoplastic elastomer layer (6) adhering to the substrate by means of an adhesion primer (5) based on a silane comprising at least one (O)nSi motif, where n is 1, 2, or 3, and at least one amine, characterized in that the adhesion by means of said primer (5) is obtained by the process as defined in any one of claims 1 to 13.

15. Glazing (10) comprising a guide rail (1) as defined in claim 14, a movable pane (3) accommodated in the guide rail (1), and optionally an element (2), such as a fixed pane, on which the guide rail (1) is fixed.

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