Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J4/00—Adhesives based on organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond ; adhesives, based on monomers of macromolecular compounds of groups C09J183/00 - C09J183/16
  • C09J4/06—Organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond in combination with a macromolecular compound other than an unsaturated polymer of groups C09J159/00 - C09J187/00

Definitions

• the present invention relates to an industrial process for manufacturing a structural adhesive as well as the application of this adhesive to assembly techniques.
• GB-A-1,348,357 describes a bonding process using an anaerobic crosslinkable acrylic composition, comprising the application of a vanadium salt of an organic acid to the surface intended to receive said composition, the latter comprising a (meth) acrylic ester of polyhydric alcohol and / or an epoxy resin, a tertiary amine and an organic hydroperoxide.
• US-A-5,180,792 describes a crosslinkable epoxy resin composition comprising a polyfunctional epoxy resin, a monofunctional (meth) acrylate such as that of phenoxyethyl or its higher counterparts and an aromatic polyamine as a crosslinker.
• application EP-A-245,559 describes a crosslinkable composition in two parts, the first part of which comprises (a) a resin mixture comprising from 60 to 95% of compounds having epoxy functional groups and from 5 to 40% of compounds having (meth) acrylate groups and (b) from 0.5 to 5% by weight of the resin mixture of a free radical photoinitiator and the second part of which comprises at least one tertiary amine and / or at least one polyoxyalkylenated polyamine.
• a first object of the present invention consists in a process for manufacturing a structural adhesive comprising continuous extrusion, at a temperature of between 60 ° C and 120 ° C approximately and for a duration of between 2 and 15 minutes approximately, of a mixture comprising:
• R 2 is a divalent group chosen from alkylene groups having from 2 to 12 carbon atoms and those comprising at least a substituted or unsubstituted aliphatic or aromatic ring, and
• diamines which can be used in the process according to the invention, mention may in particular be made of diaminodiphenylmethane,
• Polyamides with free amino functions can also be mentioned, such as in particular those obtained from (a) 35 to 49.5% by mole of dimeric fatty acid, (b) 0.5 to 15% by mole of fatty acid monomer with a chain length of 12 to 22 carbon atoms, (c) 2 to 35 mol% of polyetheramine of general formula:
• polyamides advantageously have groups acid terminals, their acid number ranging from 1 to 50, preferably from 2 to 30, in particular from 4 to 12; they can also carry amino terminal groups, their amine index ranging from 2 to 15, in particular from 4 to 10.
• aminoalkylimidazolidones of formula:
• n is an integer from 1 to 20.
• polyepoxidized resin within the meaning of the present invention, is meant a molecule having at least two epoxy functions.
• these resins are more particularly diepoxidized resins such as, for example, the diglycidyl ether of bisphenol A, butadiene diepoxide, 3,4-epoxycyclohexane-3,4-epoxycyclohexylmethyl carboxylate, vinyl-cyclohexene dioxide, 4,4'-di (1,2-epoxyethyl) diphenyl ether, 4,4 '- (1,2-epoxyethytl) biphenyl, 2,2-bis (3,4-epoxycyclohexyl) propane, diglycidyl ether resorcinol, diglycidyl ether phloroglucinol, bis (2,3-epoxycyclopentyl) ether, 2- (3,4-epoxy) cyclohexane-5,5-spiro (3,4- epoxy) -cyclo
• triepoxidized or tetraepoxidized resins such as, for example, the triglycidic ether of p-aminophenol, polyaryl glycidyl ethers, 1, 3,5-tri 2-epoxy) benzene, 2,2 ', 4,4'- tetraglycidoxybenzophenone, tetraglycidoxytetraphenylethane, the polyglycidic ether of the novolak phenol-formaldehyde resin, the glycerol ether of glycerol, the triglycidyl ether of trimethylolpropane and tetraglycidyl-4,4'-diamino-diphenyl-methane.
• the triglycidic ether of p-aminophenol polyaryl glycidyl ethers, 1, 3,5-tri 2-epoxy) benzene, 2,2 ', 4,4'- tetraglycidoxybenzoph
• (meth) acrylic epoxides which can be used in the process according to the invention, mention may in particular be made of acrylates and methacrylates of glycidyl, of (2-norbornyloxy) -2 ethyl, of (dimethanodecahydronaphthyloxy-2) -2 ethyl, 4,5-epoxypentyl, 5,6-epoxyhexyl, 6,7-epoxyheptyl, 7,8-epoxyoctyl, 8,9-epoxynonyl, 9, 10-epoxydecyl, 11, 12-epoxydodecyl, 2 , 3- epoxybutyl, 3-phenyl, 2,3-epoxypropyl, 2,5-octahydro-2-methano-2H-undeno [1,2-b] oxy-renyl and 5-hydroxy (6) [2-epoxy, ethyl] -2 bicyclo [2.2.1] h
• the molar concentrations of polyepoxidized resin Ci and of (meth) acrylic epoxide C in the mixture subjected to extrusion are linked by the inequality:
• the molar ratio, in the mixture subjected to extrusion, between the diamine on the one hand, the polyepoxidized resin and the (meth) acrylic epoxide on the other hand is such that said mixture comprises 2 epoxy functions for one function amine.
• the mixture subjected to extrusion in the process according to the invention also comprises an effective amount, for example of between 0.5% and 5% approximately by weight of the mixture, of at least one catalyst preferably chosen from Lewis acids.
• catalysts which can be used include tertiary amines, boron trifluoride etherate, phenolsulfonic acid and the methyl ester of paratoluenesulfonic acid.
• the mixture subjected to extrusion in the process according to the invention can also comprise: a) at least one polymer chosen from thermoelastic polymers and synthetic rubbers, and / or b) at least one tackifying resin, and / or c) at least one plasticizer, and / or d) at least one mineral filler, and / or e) at least one antioxidant, and / or f) at least one adjuvant of the wax or paraffin type.
• thermoelastic polymers (a) mention may be made of copolymers of ethylene and vinyl acetate or of alkyl acrylate with a high content (about 20 to 50% by weight) of acetate or acrylate and of high molecular weight (about 5,000 to 30,000).
• synthetic rubbers (a) mention may be made of block, linear or star, styrene / butadiene or styrene / isoprene copolymers, or also butadiene / acrylonitrile copolymers which are optionally functionalized at the chain end.
• the polymer thermoelastic or synthetic rubber is preferably present in an amount of up to about 20% by weight of the mixture subjected to extrusion.
• tackifying resins (b), mention may be made of polyterpenes, optionally functionalized with novolaks, rosins and rosin esters and their hydrogenated derivatives, as well as petroleum resins.
• the latter are prepared from hydrocarbon fractions originating from the steam cracking of naphthas, such as aromatic cuts containing at least one alkenylaromatic monomer, aliphatic cuts containing a monomer containing from 5 to 6 carbon atoms, such as cyclopentadiene and its derivatives and cyclohexadiene, or even terpene cuts such as turpentine.
• alkenylaromatic monomers examples include styrene, alphamethylstyrene, indene, vinyltoluene, methylindenes, betamethylstyrene and paratertiobutylstyrene.
• terpene units examples include those derived from unsaturated cyclic terpenes, preferably monounsaturated, in particular monocyclic such as 1-p-menthene and tetramethylcyclohexene and bicyclic monounsaturated such as pinenes, keels, limonene, 4 (l ⁇ ) -thujene, 5-iso-propylbicyclo [3.1.0] hex-2-ene, 4-methylenepinane, 2-bornene, 2,2,7-trimethyl-2-norbornene and camphene as well as some terpenes bi-unsaturated monocyclics such as enthadienes.
• resins which can be used in the context of the present invention are described in documents EP-A-011 393, EP-A-132 291, EP-A-233 074 and FR-A-2 659 972.
• plasticizers (c) mention may be made, on the one hand, of semi-aliphatic oils, polyisobutylenes of very low molecular weight, aromatic, naphthenic or paraffinic petroleum oils and alkylbenzenes and, on the other hand, esters derived from acids. saturated organics such as phthalates, adipates, sebacates and alkyl azelates.
• an adjuvant (fj, mention may be made of low molecular weight polyethylene waxes (generally less than 5,000) and paraffins, this adjuvant generally being present in a proportion of at most 10% by weight of the mixture subjected to extrusion.
• mineral filler mention may be made of silica, alumina, inorganic silicates, aluminates and silicoaluminates and talc, said filler preferably being present in an amount of at most 5% by weight of the mixture subjected to extrusion.
• the antioxidant (e) can be chosen in particular from 2,6-ditertiobutyl-paracresol, bishydroxy-anisol, 2,2'-thiodiethyl- bis-3- (3,5-ditertiobutyl-4-hydroxyphenyl) propionate, tetrakis- (methylene 3- (3 ', 5'-ditertiobutyl-4'-hydroxyphenyl) propionate) methane, 2,4-bis -N-octylthio-6- (4-hydroxy 3,5- ditertiobutylanilino) 1, 3,5-triazine, ditertio-butyl-3,5-hydroxy-4 phenyl-3 propionate, octadecyl-3,5- ditertio-butyl-4-hydroxy-hydro-cinnamate and mixtures thereof.
• the continuous extrusion must preferably be carried out by means of a device ensuring effective mixing of the three components of the structural adhesive, such as for example a co-rotating twin screw extruder having preferably a modular screw profile so as to be able to adjust the residence time of the material in the extruder.
• the ratio L / D between the length and the diameter of the screw is, conventionally, preferably between 25 and 45 approximately.
• the main parameters (temperature and duration) of the process according to the invention make it possible to ensure a high degree of progress of the chemical reaction between the three components of the mixture subjected to extrusion.
• the glass transition temperature of the reaction product obtained at the end of the process according to the invention (that is to say at the outlet of the extruder) is generally between -60 ° C. and 0 ° C.
• the method according to the invention further comprises, after the first step of continuous extrusion as described above, a second step of crosslinking by activation of the product obtained at the end of the first step by means of a source.
• a source for example, crosslinking can be carried out under the action of X or ultraviolet radiation.
• photo-initiators such as benzoin or its derivatives, or of photosensitizers such as benzophenone, triethylaminoethanol or benzophenone triethylamine, crosslinking taking place at room temperature and the exposure time varying from a few seconds to a few minutes.
• Another method consists in the action of an accelerated electron beam with an energy of between 0.2 and 10 mega eV approximately, at room temperature.
• a free radical initiator chosen as a function of its half-life at the temperature considered, may in particular be a diazo compound, a hydroperoxide or else a peroxide such as tert-butyl perbenzoate or ditertiobutyl peroxide.
• This initiator is preferably present in an amount of approximately 1% to 5% by weight of the mixture subjected to extrusion.
• a three-dimensional polymer network is formed, the glass transition temperature of which is generally between approximately 120 ° C. and 160 ° C.
• the product obtained at the outlet of the extruder is directly applicable on any support for the second step of the process.
• This application can in particular be carried out by coating on supports of all kinds, such as inert plastic film, metal sheet, reinforcements, etc.
• a second object of the present invention consists of an assembly process using the structural adhesive obtained as described above.
• This process therefore consists in joining two materials together using an intermediate layer of structural adhesive obtained by extruding the mixture described above and then crosslinking.
• the assembly can in particular be carried out by applying a second material to a first material previously coated with the product leaving the extruder, and incorporating at least one free radical initiator, then subjecting the assembly to the conditions of temperature and duration capable cause cross-linking of the adhesive.
• the present invention is particularly suitable for metal-polymer, metal-metal or polymer-polymer assembly in the areas where high performance is required under stress, high durability, high environmental resistance (temperature, solvents) and high productivity.
• the extrusion is carried out at a temperature of 90 ° C. for a period of 8 minutes.
• the product from the extruder after this first step has a glass transition temperature of -59 ° C.
• the second step of the process is carried out under the same conditions as in Example 1, with the sole exception of the average thickness of the layer deposited on the sheet, which here is equal to 370 ⁇ m.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Adhesives Or Adhesive Processes (AREA)
• Extrusion Moulding Of Plastics Or The Like (AREA)

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Citations (3)

• 1993
  • 1993-06-24 FR FR9307678A patent/FR2706903B1/fr not_active Expired - Fee Related
• 1994
  • 1994-06-17 WO PCT/FR1994/000731 patent/WO1995000598A1/fr active Application Filing

Patent Citations (3)

Non-Patent Citations (1)

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