NEW NETWORKABLE COMPOSITION WITH SILYL-TERMINED POLYMER AND ASSOCIATED SELF-ADHESIVE ITEM

Description

FIELD OF THE INVENTION

[0001] The present invention relates to a self-adhesive article, in particular a self-adhesive support which comprises a support layer coated with a self-adhesive layer consisting of a crosslinkable adhesive composition, in the crosslinked state. Finally, it relates to a method for manufacturing said article. TECHNICAL BACKGROUND

[0002] Pressure-sensitive adhesives (also known as pressure-sensitive adhesives or PSAs) are substances that give the backing layer coated with them immediate tack at room temperature. Often referred to as "tack" or sometimes as "stickiness," this immediate tack allows the self-adhesive backing to adhere instantly to all kinds of substrates, under the effect of light, brief pressure.

[0003] Due to its adhesive power, usually assessed by a peel test, said self-adhesive support is then firmly fixed to said substrate, by means of an adhesive seal.

[0004] PSAs are widely used for the manufacture of self-adhesive articles, such as self-adhesive labels which are attached to articles for the purpose of displaying information (such as barcode, name, price) and / or for decorative purposes, whether in permanent or temporary bonding.

[0005] PSAs are also used in the manufacture of self-adhesive tapes for a variety of uses. Examples include, in addition to the transparent adhesive tape widely used in everyday life: shaping and assembling cardboard packaging; protecting surfaces for painting work in construction; fixing and holding various elements such as panels, bricks, protruding objects, in the construction of buildings or structures; fixing and holding metal, plastic, or glass parts, whether flat or with specific profiles, such as electrical cables, plastic films, windows, sheet metal, inscriptions, logos, parts of seats, dashboards, plastic or textile walls, conduits or pipes for circulating fluids, particularly in the transport industry; bonding carpets using double-sided adhesive tapes in the construction industry.

[0006] For the purpose of manufacturing self-adhesive articles (e.g. self-adhesive labels and / or tapes), PSAs are generally applied by continuous coating processes to the entire surface of a large (if applicable printable) carrier layer, in a quantity (generally expressed in g / m 2 < ) and hereinafter referred to as "grammage". The carrier layer is, for example, paper or a film made of a polymer material with one or more layers. The layer of self-adhesive composition covering the carrier layer may itself be covered with a protective release layer (often referred to as a "release liner"), for example made of a silicone film. The resulting multi-layer system is generally packaged by winding in the form of large reels up to 2 m wide and 1 m in diameter, which can be stored and transported.

[0007] These multi-layer systems can be subsequently converted into self-adhesive labels applicable by the end user, by means of transformation processes that include printing the desired informative and / or decorative elements on the printable side of the carrier layer, then cutting them to the desired shape and dimensions. The protective release layer can be easily removed without modifying the adhesive layer that remains attached to the carrier layer. After separation from its protective release layer, the label is applied to the article to be coated either manually or using labeling machines on automated packaging lines.

[0008] These multi-layer systems can also be transformed into self-adhesive tapes by cutting and packaging in rolls of determined widths and lengths with, if necessary, the cutting or pre-cutting of particular shapes useful for their final use, such as for the assembly of parts of variable size and variable shape, in the electronics industry, whether for applications in industry or by the general public.

[0009] Due to their high tack at room temperature, PSAs allow rapid adhesion or adhesion of the self-adhesive label and / or tape to the substrate (or article) to be coated (for example, in the case of labels, on bottles or, in the case of tapes, on packaging cartons to be shaped), suitable for obtaining high industrial production rates.

[0010] There is a field of application of PSAs for which it is desirable that the adhesive power of the labels and / or tapes on the substrate is also maintained when the glue joint ensuring the attachment is exposed (as is, consequently, the article coated with the label and / or tape) to a temperature likely to vary over a wide range. Examples include the application of labels to certain components of automobiles (or other vehicles) located near the engine, or to packaging designed to receive a hot liquid during its packaging, or to articles (such as tires) which are hot-labeled, as they come off the production lines. Also, mention may be made of the use of self-adhesive tapes for the assembly of parts for which good thermal resistance is necessary, as in the case, for example, of the interior trim of airplanes or other vehicles.

[0011] PSAs often used for this application area include acrylate-type polymers (or copolymers) with a very high number-average molecular weight (Mn). These are available in the form of either an aqueous emulsion or an organic solution. However, coating such PSAs onto a support layer is complicated, from an industrial perspective, by the fact that it is necessary to provide either an additional step for drying the emulsion or special installations that take into account industrial hygiene and safety problems related to the evaporation of the organic solvent. In both cases, the disadvantages related to the unpleasant odor of acrylics must also be taken into account.

[0012] US Patent 6,486,229 describes a UV-curable hot-melt adhesive composition comprising a tackifying resin, a photoinitiator, and a radial styrene-butadiene multiblock copolymer, the butadiene block of which has a high pendant vinyl group content. This composition is coated in the uncrosslinked state onto a backing layer and then crosslinked by exposure to ultraviolet radiation. The resulting self-adhesive backing is particularly suitable for tape and label applications where good cohesion at elevated temperatures is required. International application WO 2004 / 011559 describes a coatable acrylic composition comprising an acrylic copolymer, a photoinitiator, and a multifunctional (meth)acrylate. This composition can also be crosslinked by exposure to ultraviolet radiation to provide a high-performance PSA.

[0013] These techniques for obtaining PSA by UV, however, have disadvantages which arise from industrial hygiene problems linked to UV lamps and the costs associated with their short service life. In addition, in the case of self-adhesive supports with a high PSA weight, for example a weight greater than 150 g / m 2 < , it is difficult to ensure that the adhesive power is maintained over a wide temperature range, and in particular at high temperature, due to the difficulty of penetration of UV radiation over the entire thickness of the crosslinkable adhesive layer. Finally, another disadvantage of crosslinking by UV exposure is that crosslinking stops as soon as the composition is no longer exposed to UV radiation; thus, the crosslinking reaction cannot continue and be completed after the coated support layer has left the production line, for example during storage.

[0014] Adhesive compositions based on polyurethane (or polyether) with alkoxysilane terminations which are crosslinkable by heating are already known, in particular from the three applications of Bostik SA: WO 09 / 106699, EP2336208 and WO 2020 / 128200. These adhesive compositions are advantageously solvent- and water-free. Coating them on a support and heating them to a temperature between 50 and 150°C leads, at the end of a chemical crosslinking reaction also carried out in the presence of moisture, to the production of a self-adhesive support which has the required properties of adhesive power (or peel) and tack. This crosslinking reaction leads to the formation of an adhesive joint which has a three-dimensional polymer network structure comprising siloxane bonds and which ensures the fixing of the self-adhesive support to the substrate. The self-adhesive support can thus be used for the manufacture of labels and / or self-adhesive tapes.

[0015] Application WO 12 / 090151 by Bostik SA describes a method for crosslinking an adhesive composition based on polyurethane (or polyether) with alkoxysilane termination, which uses a Caroll-type guiding means in a climatic chamber whose temperature is between 50°C and 200°C and whose relative humidity is preferably controlled at a value of approximately 50%.

[0016] Application FR 3013993 by Bostik SA describes a method for applying an adhesive composition comprising a reactive prepolymer, in particular an alkoxysilane-terminated prepolymer, said method comprising heating said composition in line by electrically supplying an inductor cable, upstream of its hot application to a support using an application nozzle and at a temperature between 50°C and 200°C.

[0017] JP 2019 147925 A, EP 2 615 147 A1, JP 2014 001319 A and EP 1 095 981 A1 disclose an adhesive composition comprising a resin composition including a copolymer having a hydrolyzable alkoxysilane group, a fumed silica, a tackifying resin and a crosslinking catalyst.

[0018] WO 2015 / 195391 A1 discloses a self-adhesive composition comprising at least one ethylenically unsaturated monomer forming a polymer having a low glass transition temperature, and at least one crosslinking agent based on a silsesquioxane polymer comprising a plurality of ethylenically unsaturated groups.

[0019] The aim of the present invention is to simplify the method of manufacturing a self-adhesive article, in particular a self-adhesive support, by crosslinking a crosslinkable adhesive composition based on a polymer with an alkoxysilane termination.

[0020] The present invention also aims to provide a crosslinkable adhesive composition based on an alkoxysilane-terminated polymer, which makes it possible to manufacture a self-adhesive article, in particular a self-adhesive support, by crosslinking at a lower temperature, in particular at a temperature below 50°C, and even at room temperature.

[0021] The present invention also aims to provide a crosslinkable adhesive composition based on an alkoxysilane-terminated polymer, which makes it possible to manufacture a self-adhesive article, in particular a self-adhesive support, by crosslinking without controlling or regulating the relative humidity.

[0022] Another object of the present invention is to provide a crosslinkable adhesive composition which crosslinks at ambient temperature and / or humidity in a reduced time.

[0023] Another aim of the present invention is to provide a crosslinkable adhesive composition which, after coating on a support and then crosslinking, leads to a pressure-sensitive adhesive having suitable adhesive power and tack properties.

[0024] Another aim of the invention is that the adhesive joint which ensures the fixing of the self-adhesive support thus obtained on a substrate maintains the required cohesion over a wide temperature range, including for high PSA weights.

[0025] Another object of the invention is that the adhesive seal has improved mechanical resistance.

[0026] It has now been found that these objects can be achieved in whole or in part by means of the adhesive composition and the self-adhesive backing which are described below. DESCRIPTION OF THE INVENTION Crosslinkable adhesive composition :

[0027] The present invention therefore relates firstly to a self-adhesive article comprising a support layer coated with a self-adhesive layer, characterized in that said self-adhesive layer consists of a crosslinkable adhesive composition, in the crosslinked state, the crosslinkable adhesive composition being characterized in that it comprises: at least one polymer (A) comprising a hydrolyzable alkoxysilane group; at least one tackifying resin (B); at least one fumed silica (C); and at least one crosslinking catalyst (D); and a silsesquioxane resin (E).

[0028] It has now been found that said crosslinkable composition offers a considerably reduced crosslinking time, at ambient temperature and humidity. It can thus advantageously lead, after its coating on a support layer and its crosslinking, to a self-adhesive support, at the end of a process which implements a heating step at a lower temperature and does not require high relative humidity, or even at the end of a process which does not require a heating step and / or humidity control.

[0029] In addition, said self-adhesive support also exhibits conformal properties of adhesive power (or peel) on a substrate such as stainless steel, which make it suitable for firmly fixing to said substrate. The adhesive joint which ensures the fixing of said support on the substrate maintains, quite surprisingly, a much better cohesion in temperature, thanks to an improved resistance to shear tests at constant temperature at 125°C.

[0030] Finally, the self-adhesive layer consisting of the crosslinkable adhesive composition in the crosslinked state is advantageously provided with greater mechanical resistance, quantified by measuring the breaking stress. Polymer (A):

[0031] For the purposes of the present invention, the term “polymer (A) comprising a hydrolyzable alkoxysilane group” means a polymer which comprises at least one, and preferably at least two, hydrolyzable groups of formula (I): -Si(R 4< ) p (OR 5< ) 3-p (I) in which: R 4< represents a linear or branched alkyl radical comprising from 1 to 4 carbon atoms, with the possibility that when there are several R 4< radicals, the latter are identical or different; R 5< represents a linear or branched alkyl radical comprising from 1 to 4 carbon atoms, with the possibility that when there are several R 5< radicals, the latter are identical or different, with the possibility that two OR 5< groups can be engaged in the same cycle; and p is an integer equal to 0, 1 or 2, preferably equal to 0 or 1.

[0032] The hydrolyzable alkoxysilane group is preferably positioned at the end of said polymer. However, positioning in the middle of the chain is not excluded. The polymer (A) is not crosslinked before application of the adhesive composition. The adhesive composition is applied under conditions allowing its crosslinking.

[0033] The polymer (A) is therefore a silylated polymer which is generally in the form of a more or less viscous liquid. Preferably, the polymer (A) has a viscosity, in particular at 23°C, ranging from 10 to 200 Pa.s, preferably ranging from 20 to 175 Pa.s, said viscosity being for example measured according to a Brookfield type method at 23°C and 50% relative humidity (needle S28).

[0034] The polymer (A) preferably comprises two groups of formula (I), but it can also comprise from three to six groups of formula (I).

[0035] Preferably, the polymer(s) (A) have a number-average molecular mass (Mn) ranging from 500 to 50,000 g / mol, more preferably ranging from 700 to 20,000 g / mol. The number-average molecular mass (Mn) of the polymers can be calculated or measured by methods well known to those skilled in the art, for example by NMR and size exclusion chromatography using polystyrene-type standards.

[0036] According to one embodiment of the invention, the polymer (A) corresponds to one of the formulas (II), (III) or (IV): in which: R 4< , R 5< and p have the same meaning as in formula (I) described above, P represents a saturated or unsaturated, linear or branched polymeric radical optionally comprising one or more heteroatoms, such as oxygen, nitrogen, sulfur, silicon, and preferably having a number-average molecular mass (Mn) ranging from 100 g / mol to 48600 g / mol, more particularly from 300 g / mol to 18600 g / mol or from 500 g / mol to 12600 g / mol, R 1< represents a divalent hydrocarbon radical comprising from 5 to 15 carbon atoms which may be aromatic or aliphatic, linear, branched or cyclic, R 3< represents a divalent linear or branched alkylene radical comprising from 1 to 6 carbon atoms, preferably from 1 to 3 carbon atoms, X represents a divalent radical chosen from -NH-, -NR 7< - or -S-, R 7< represents a linear or branched alkyl radical comprising from 1 to 20 carbon atoms and which may also comprise one or more heteroatoms,and f is an integer ranging from 1 to 6, preferably ranging from 2 to 5, preferably from 2 to 4, more preferably ranging from 2 to 3.,

[0037] Preferably, in formulas (II), (III) and / or (IV) above, P represents a polymeric radical chosen in a non-limiting manner from polyethers, polycarbonates, polyesters, polyolefins, polyacrylates, polyether polyurethanes, polyester polyurethanes, polyolefin polyurethanes, polyacrylate polyurethanes, polycarbonate polyurethanes, polyether / polyester block polyurethanes.

[0038] For example, document EP 2468783 describes silylated polymers of formula (II) in which P represents a polyurethane / polyester / polyether block polymer radical.

[0039] According to one embodiment, the silylated polymers are chosen from silylated polyurethanes, silylated polyethers, and mixtures thereof.

[0040] According to a particular embodiment, the silylated polymer (A) corresponds to one of the formulas (II'), (III') or (IV'): in which: R 1< , R 3< , R 4< , R 5< , X, R 7< and p have the same meaning as in formulae (II), (III) and (IV) described above, R 2< represents a saturated or unsaturated, linear or branched divalent hydrocarbon radical optionally comprising one or more heteroatoms, such as oxygen, nitrogen, sulfur, silicon, and preferably having a number-average molecular mass (Mn) ranging from 100 g / mol to 48600 g / mol, more particularly from 300 g / mol to 18600 g / mol or from 500 g / mol to 12600 g / mol, and n is an integer greater than or equal to 0.

[0041] In the silylated polymers of formulae (II'), (III') or (IV') defined above, when the radical R 2< comprises one or more heteroatoms, said heteroatoms are not present at the end of the chain. In other words, the free valences of the divalent radical R 2< linked to the oxygen atoms adjacent to the silylated polymer each come from a carbon atom. Thus, the main chain of the radical R 2< is terminated by a carbon atom at each of the two ends, said carbon atom then having a free valence.

[0042] According to one embodiment, the silylated polymers (A) are obtained from polyols chosen from polyether polyols, polyester polyols, polycarbonate polyols, polyacrylate polyols, polysiloxane polyols and polyolefin polyols and mixtures thereof, and more preferably from diols chosen from polyether diols, polyester diols, polycarbonate diols, polyacrylate diols, polysiloxane diols, polyolefin diols and mixtures thereof. In the case of the polymers of formulae (II'), (III') or (IV') described above, such diols may be represented by the formula HO-R 2< -OH where R 2< has the same meaning as in formulae (II'), (III') or (IV').

[0043] For example, among the radicals of type R 2< which can be present in formulas (II'), (III') or (IV'), we can cite the following divalent radicals whose formulas below show the 2 free valencies: derived from a polypropylene glycol: derived from a polyester diol: derivative of a polybutadiene diol: derivative of a polyacrylate diol: derived from a polysiloxane diol:

[0044] In the above formulas, the meaning of the radicals and indices is as follows: q represents an integer such that the number-average molecular mass of the radical R 2< ranges from 100 g / mol to 48600 g / mol, preferably from 300 g / mol to 18600 g / mol, more preferably from 500 g / mol to 12600 g / mol, r and s represent zero or a non-zero integer such that the number-average molecular mass (Mn) of the radical R 2< ranges from 100 g / mol to 48600 g / mol, preferably from 300 g / mol to 18600 g / mol, more preferably from 500 g / mol to 12600 g / mol, it being understood that the sum r+s is different from zero, Q 1< represents a linear or branched, saturated or unsaturated, aromatic or aliphatic divalent alkylene radical, preferably having from 1 to 18 carbon atoms, more preferably from 1 to 8 carbon atoms. carbon, Q 2< represents a linear or branched divalent alkylene radical preferably having from 2 to 36 carbon atoms, more preferably from 1 to 8 carbon atoms, Q 3< , Q 4< , Q 5< , Q 6< , Q 7< and Q 8< , represent, independently of each other,a hydrogen atom or an alkyl, alkenyl or aromatic radical, preferably having from 1 to 12 carbon atoms, preferably from 2 to 12 carbon atoms, more preferably from 2 to 8 carbon atoms.

[0045] According to the embodiment of the composition according to the invention, the silylated polymer (A) is such that the radical R 2< which appears in the formulas (II'), (III') and (IV') represents a polyether radical, preferably a poly(oxyalkylene) radical, and even more preferably a radical derived from a polypropylene glycol corresponding to the formula indicated above.

[0046] According to one embodiment, R 1< is chosen from one of the following divalent radicals whose formulas below show the 2 free valences: a) the divalent radical derived from isophorone diisocyanate (IPDI): b) the divalent radical derived from dicyclohexylmethane diisocyanate (H12MDI) c) the divalent radical derived from toluene diisocyanate (TDI) d) divalent radicals derived from the 4,4' and 2,4'- isomers of diphenylmethane diisocyanate (MDI) e) the divalent radical derived from hexamethylene diisocyanate (HDI) -(CH 2 ) 6 - f) the divalent radical derived from m-xylylene diisocyanate (m-XDI)

[0047] The polymers of formula (II) or (II') can be obtained according to a process described in documents EP 2336208 and WO 2009 / 106699. Those skilled in the art will be able to adapt the manufacturing process described in these two documents in the case of the use of different types of polyols. Among the polymers corresponding to formula (II), mention may be made of: GENIOSIL ®< STP-E10 (available from WACKER): polyether comprising two dimethoxy groups (I) (n equal to 0, p equal to 1 and R 4< and R 5< represent a methyl group) with a number-average molecular weight of 8889 g / mol where R 3< represents a methyl group; GENIOSIL ®< STP-E30 (available from WACKER): with a number-average molecular weight of 14493 g / mol, it is a polypropylene glycol with 2 end groups consisting of a dimethoxy(methyl)silylmethylcarbamate, i.e. in formula (II'): n equal to 0; p equal to 1; R 4< and R 5< represent a methyl group and R 3< represents a methyl group; DESMOSEAL ®< S XP 2636 (available from BAYER): polyurethane comprising two groups (I) of the trimethoxy type (n different from 0, p equal to 0 and R 5< represents a methyl group) having a number-average molecular mass of 15038 g / mol where R 3< represents an n-propylene group.

[0048] The polymers of formula (III) or (III') can be obtained by hydrosilylation of polyether diallyl ether according to a process described for example in document EP 1829928. Among the polymers corresponding to formula (III), mention may be made of: the polymer MS SAX ®< 350 (available from KANEKA) corresponding to a polyether comprising two groups (I) of dimethoxy type (p equal to 1 and R 4< and R 5< represent a methyl group) having a number-average molecular mass ranging from 14000 to 16000 g / mol; the polymer MS SAX ®< 260 (available from KANEKA) corresponding to a polyether comprising two groups (I) of dimethoxy type (p equal to 1, R 4< and R 5< represent a methyl group) having a number-average molecular mass of 16000 to 18000 g / mol where R 3< represents an ethyl group; the MS S303H polymer (available from KANEKA) corresponding to a polyether comprising two groups (I) of dimethoxy type (p is equal to 1 and R 4< represents a methyl group) having a number-average molecular mass of approximately 22,000 g / mol.

[0049] The polymers of formula (IV) or (IV') may for example be obtained by reaction of polyol(s) with one or more diisocyanate(s) followed by a reaction with aminosilanes or mercaptosilanes. A process for preparing polymers of formula (IV) or (IV') is described in document EP 2 583 988. A person skilled in the art will be able to adapt the manufacturing process described in this document in the case of the use of different types of polyols. Among the polymers corresponding to formula (IV) or (IV'), mention may be made of: SPUR+ ®< 1050MM (available from MOMENTIVE): polyurethane comprising two groups (I) of the trimethoxy type (n different from 0, p equal to 0 and R 5< represents a methyl group) having a number average molecular weight of 16393 g / mol where R 3< represents an n-propyl group; SPUR+ ®< Y-19116 (available from MOMENTIVE): polyurethane comprising two groups (I) of the trimethoxy type (n different from 0 and R 5< represents a methyl group) having a number average molecular weight ranging from 15000 to 17000 g / mol g / mol where R 3< represents an n-propyl group.

[0050] According to a preferred embodiment of the invention, the adhesive composition comprises at least one silylated polymer (A) of formula (II) and / or (II') or at least one silylated polymer (A) of formula (III) and / or (III').

[0051] According to a very particularly preferred embodiment of the invention, the polymer (A) is a silylated polymer of formula (II') in which n equals 0, R 2< is a divalent radical derived from a polyether, preferably from a poly(oxyalkylene) diol, and even more particularly from a polypropylene glycol. Tackifying resin (B) :

[0052] The crosslinkable adhesive composition according to the invention also comprises at least one tackifying resin (B).

[0053] Said resin may be any resin compatible with the silylated polymer(s) (A).

[0054] The term "compatible tackifying resin" is intended to mean a tackifying resin which, when mixed in proportions of 50% / 50% (particularly by weight) with the polymer(s) (A), gives a substantially homogeneous mixture.

[0055] The resins (B) are advantageously chosen from: (i) resins obtained by polymerization of terpenic hydrocarbons and phenols, in the presence of Friedel-Crafts catalysts; (ii) resins obtained by a process comprising the polymerization of alpha-methyl styrene, said process possibly also comprising a reaction with phenols; (iii) rosins of natural or modified origin, (such as for example rosin extracted from pine gum, wood rosin extracted from the roots of the tree and their derivatives hydrogenated, dimerized, polymerized or esterified by monoalcohols or polyols, such as glycerol or pentaerythritol); (iv) resins obtained by hydrogenation, polymerization or copolymerization (with an aromatic hydrocarbon) of mixtures of unsaturated aliphatic hydrocarbons having approximately 5, 9 or 10 carbon atoms derived from petroleum fractions;(v) terpene resins (which generally result from the polymerization of terpene hydrocarbons - such as mono-terpene (or pinene) - in the presence of Friedel-Crafts catalysts); (vi) copolymers based on natural terpenes (such as, for example, styrene / terpene, alpha-methyl styrene / terpene and vinyl toluene / terpene); or (vii) acrylic resins having a viscosity at 100°C of less than 100 Pa.s; as well as among mixtures of these resins.

[0056] Such resins are commercially available and among those of type (i), (ii), (iii) and (iv) defined above, the following products may be mentioned: resins of type (i): Dertophene ®< 1510 available from the company DRT having a number average molecular mass (Mn) of approximately 870 Da; Dertophene ®< H150 available from the same company with a number average molecular mass (Mn) equal to approximately 630 Da; Sylvarez ®< TP 95 available from the company Arizona Chemical having a number average molecular mass (Mn) of approximately 1200 Da; resins of type (ii): Cleartack ®< W100 available from the company Cray Valley, which is obtained by polymerization of alpha-methyl styrene without the action of phenols, with a number average molecular mass (Mn) of 900 Da; Sylvarez ®< 510 which is also available from Arizona Chemical Company with a number average molecular weight (Mn) of approximately 1740 Da, the production process of which also includes the addition of phenols;resins of type (iii): Sylvalite ®< RE 100 which is an ester of rosin and pentaerethritol available from the Arizona Chemical company and with a number-average molecular mass (Mn) of approximately 1700 Da; resins of type (iv): Picco ®< AR100 available from the Eastman company and with a number-average molecular mass (Mn) of approximately 550 g / mol. ;

[0057] According to a preferred variant, a resin chosen from those of type (i) or (iv) is used as resin (B). Fumed silica (C) :

[0058] Fumed silica (also called "fumed silica") is a very fine silica particle (in the nanometer range), with a very low bulk density and a very high specific surface area. Fumed silica can be obtained by pyrolysis, in the presence of hydrogen and oxygen, of silicon compounds, such as silicon tetrachloride, itself prepared from silicon and chlorine.

[0059] Fumed silica is initially hydrophilic, due to the presence of silanol groups (Si-OH) on the surface of its constituent particles. It can be made hydrophobic by reacting these silanol groups with various reagents, usually a silicone oil, such as PolyDiMethylSiloxane (PDMS).

[0060] Preferably, the fumed silica (C) is a hydrophobic fumed silica.

[0061] According to one embodiment, the hydrophobic fumed silica (C) is obtained by treating a fumed silica with a PolyDiMethylSiloxane.

[0062] According to one embodiment, the fumed silica (C) has a BET specific surface area of ​​at least 10 m 2 < / g, preferably ranging from 50 to 400 m 2 < / g, even more preferably from 80 to 290 m 2 < / g. The BET specific surface area is measured, in a manner well known to those skilled in the art, by determining an adsorption isotherm based on the Brunauer, Emmett and Teller (BET) method, for example according to the ISO 9277 standard of September 2010.

[0063] According to another embodiment, the fumed silica (C) is obtained by a compaction treatment, for example from a roller compactor or the process described by patent EP 0 280 851. The apparent density is quantified by a measurement of the tamped apparent density, measured according to standard ISO 787 / 11 of August 1983, which is generally within a range from 50 to 200 g / l.

[0064] Such pyrogenic silicas, particularly hydrophobic ones, are commercially available, such as the products in the AEROSIL ® range from the company EVONIK.

[0065] An example of hydrophobic fumed silica (C) is AEROSIL ®< R202, whose BET specific surface area is 100±20 m 2< / g, the bulk density of approximately 60 g / l, and which is made hydrophobic by treatment with PolyDiMethylSiloxane. The constituent particles of AEROSIL ®< R202 have a size of approximately 16 nm. Crosslinking catalyst (D) :

[0066] The crosslinking catalyst (D) that can be used in the composition according to the invention can be any catalyst known to those skilled in the art for the condensation of silanol. Examples of such catalysts that may be mentioned are organic titanium derivatives such as titanium acetyl acetonate (commercially available under the name TYZOR ®< AA75 from the company DuPont), aluminum such as aluminum chelate (commercially available under the name K-KAT ®< 5218 from the company King Industries), amines such as 1,8-diazobicyclo (5.4.0) undecene-7 or DBU. Silsesquioxane resin (E) :

[0067] In addition to ingredients (A), (B), (C) and (D), the crosslinkable adhesive composition according to the invention also comprises a silsesquioxane resin (E).

[0068] According to a preferred variant of the invention, the crosslinkable adhesive composition according to the invention comprises at least one such silsesquioxane resin.

[0069] Silsesquioxane resins are organic silicon compounds that can adopt a polyhedral structure or a polymeric structure, with Si-O-Si bonds. They generally have the following general formula: [RSiO 3 / 2 ]t in which R, of identical or different nature, represents an organic radical, and t is an integer that can vary from 6 to 12, preferably t equals 6, 8, 10 or 12.

[0070] According to one embodiment, the silsesquioxane (E) has a polyhedral structure (or POSS for “Polyhedral Oligomeric Silsesquioxane” in English).

[0071] Preferably, the silsesquioxane (E) corresponds to the following general formula (V): in which each of R' 1< to R' 8< represents, independently of each other, a group chosen from: a hydrogen atom, a radical selected from the group consisting of a linear or branched C1-C4 alkoxy radical, a linear or branched alkyl radical comprising from 1 to 30 carbon atoms, an alkenyl radical comprising from 2 to 30 carbon atoms, an aromatic radical comprising from 6 to 30 carbon atoms, an allyl radical comprising from 3 to 30 carbon atoms, an aliphatic cyclic radical comprising from 3 to 30 carbon atoms, an acyl radical comprising from 1 to 30 carbon atoms, and a group -OSiR' 9< R' 10< in which R' 9< and R' 10< each represents, independently of one another, a hydrogen atom or a radical selected from the group consisting of linear or branched C1-C4 alkyls, linear or branched C1-C4 alkoxys, alkenyls C2-C4, a phenyl, a C3-C6 allyl radical, a C3-C8 cyclic aliphatic radical, and a C1-C4 acyl radical; provided: that at least one radical among the radicals R' 1< to R' 8< is a C1-C4 alkoxy radical; and that at least one radical among the radicals R' 1< to R' 8< is a phenyl radical.

[0072] In particular, silsesquioxane (E) is a dimethylmethoxyphenyl siloxane (CAS number = 68957-04-0).

[0073] Silsesquioxanes are known compounds which are described in particular in application WO 2008 / 107331. Some are also commercially available, such as the DOW product marketed under the name: DOW CORNING ®< 3074 and DOW CORNING ®< 3037 (CAS number = 68957-04-0). Other additives :

[0074] The crosslinkable adhesive composition according to the invention may also comprise one or more additives chosen from the group consisting of moisture absorbers, plasticizers, antioxidants, pigments, dyes, adhesion promoters, UV stabilizers, flame retardant additives or even fillers such as carbonate fillers, for example of the calcium carbonate type.

[0075] The moisture absorber (or desiccant) may be, for example, selected from hydrolyzable, non-polymeric alkoxysilane derivatives with a molecular weight of less than 500 g / mol, preferably selected from trimethoxysilane and triethoxysilane derivatives. Such an agent may typically extend the shelf life of the composition during storage and transportation prior to use. Examples include gamma-metacryloxypropyltrimethoxysilane (for example, available under the trade name SILQUEST ®< A-174 from MOMENTIVE), methacryloxymethyltrimethoxysilane (for example, available under the name GENIOSIL ®< XL33 from WACKER), vinyltrimethoxysilane, isooctyltrimethoxysilane, or phenyltrimethoxysilane.

[0076] When present, the moisture absorber may for example represent from 0.1% to 3% by weight or from 1% to 2% by weight relative to the total weight of the composition according to the invention.

[0077] The composition according to the invention may also comprise a plasticizing agent.

[0078] As an example of a plasticizing agent that can be used, any plasticizing agent commonly used in the field of adhesives may be used, such as, for example, phthalates, benzoates, trimethylolpropane esters, trimethylolethane esters, trimethylolmethane esters, glycerol esters, pentaerythritol esters, naphthenic mineral oils, adipates, cyclohexanedicarboxylates, paraffinic oils, natural oils (optionally epoxidized), polypropylenes, polybutylenes, hydrogenated polyisoprenes, and mixtures thereof.

[0079] Examples of phthalates include diisononyl phthalate, diisobutyl phthalate, dioctyl phthalate, dicyclohexyl phthalate, diisooctyl phthalate, diisododecyl phthalate, dibenzyl phthalate or butylbenzyl phthalate.

[0080] Examples of benzoates include: neopentyl glycol dibenzoate (e.g. available under the name UNIPLEX ®< 512 from LANXESS), dipropylene glycol dibenzoate (e.g. available under the name BENZOFLEX ®< 9-88SG from EASTMAN), a mixture of diethylene glycol dibenzoate and dipropylene glycol dibenzoate (e.g. available under the name K-FLEX ®< 850 S from KALAMA CHEMICAL), or a mixture of diethylene glycol dibenzoate, dipropylene glycol dibenzoate and triethylene glycol dibenzoate (e.g. available under the name BENZOFLEX ®< 2088 from EASTMAN).

[0081] Among the pentaerythritol esters, we can for example cite pentaerythritol tetravalerate (for example available under the name PEVALEN ™ from the company PESTORP).

[0082] Examples of cyclohexanedicarboxylates include diisononyl 1,2-cyclohexanedicarboxylate (e.g. available under the name HEXAMOLL DINCH ®< from BASF) and 1,4-bis(2-ethylhexyl)-1,4-cyclohexanedicarboxylate (e.g. available under the name DEHCH from CONNECT CHEMICALS).

[0083] The total content of plasticizer(s) in the composition according to the invention may range from 0% to 30% by weight, preferably from 1% to 30% by weight, or even for example from 1% to 15% by weight relative to the total weight of said composition.

[0084] The composition according to the invention may also comprise an antioxidant (also referred to as a UV stabilizing agent).

[0085] Antioxidants are compounds that can be introduced to protect the composition from degradation resulting from a reaction with oxygen that is likely to form by the action of heat or light. These compounds can include primary antioxidants that scavenge free radicals. Primary antioxidants can be used alone or in combination with other secondary antioxidants or UV stabilizers.

[0086] Examples include IRGANOX ®< 1010, IRGANOX ®< B561, IRGANOX ®< 245, IRGANOX ®< 1076, IRGAFOS ®< 168 marketed by BASF.

[0087] An amount of antioxidant ranging from 0.1% to 3%, preferably from 1% to 3% by weight, based on the total weight of the composition according to the invention is generally used.

[0088] According to one embodiment, the crosslinkable adhesive composition according to the invention comprises: from 3% to 90% by weight, preferably from 5% to 80% by weight, preferentially from 10% to 70% by weight, in particular from 20% to 60% by weight, advantageously from 36% to 56% by weight of at least one polymer (A) comprising a hydrolyzable alkoxysilane group; from 8% to 80% by weight, in particular from 15% to 80% by weight, preferably from 20% to 70%, preferentially from 25% to 70%, in particular from 30% to 60%, advantageously from 40% to 60% by weight of at least one tackifying resin (B); from 1% to 10% by weight, preferably from 2% to 8%, advantageously from 2% to 6% by weight of the fumed silica (C); and from 0.01% to 10% by weight, preferably from 0.01% to 5%, preferentially from 0.05% to 4%, advantageously from 0.1% to 3%, in particular from 0.5% to 2% by weight of crosslinking catalyst (D); these percentages by weight being indicated on the basis of the total weight of said composition.

[0089] When, according to a preferred variant of the invention, the crosslinkable adhesive composition further comprises a silsesquioxane resin (E), the amount thereof may vary from 0.1 to 20% by weight, preferably from 1% to 20% by weight, preferentially from 2% to 15% by weight, advantageously from 3% to 12% by weight, based on the total weight of said composition.

[0090] The crosslinkable adhesive composition according to the invention can be prepared by a process which comprises: a step of mixing, protected from air, preferably under an inert atmosphere, the polymer (A), the tackifying resin (B), and, where appropriate, the other optional additives, to form a part (PA); then a step of mixing the crosslinking catalyst (D) with, when present, the silsesquioxane resin (E); to form a part (PB); then a step of incorporating the fumed silica (C) into the part (PA), at a temperature between 50 and 180°C, preferably between 100 and 150°C, until a homogeneous mixture (PC) is obtained; and finally a step of mixing (PC) with (PB). Article self-adhesive:

[0091] The present invention also relates to a self-adhesive article comprising a support layer coated with a self-adhesive layer, characterized in that said self-adhesive layer consists of the adhesive composition according to the invention in the crosslinked state.

[0092] For the purposes of the present invention, the term "self-adhesive article" includes any article that can be adhered to a surface solely by the action of pressure with the hand or equipment, without the use of additional glues or adhesives.

[0093] The self-adhesive article is a pressure-sensitive self-adhesive article.

[0094] The backing layer coated with a self-adhesive layer is also referred to as "self-adhesive backing".

[0095] These articles are intended in particular to be applied to a surface to be bonded in order to bring together, maintain, fix, assemble or simply immobilize, expose shapes, logos, images or information. These articles can be used in many fields, such as the medical field, clothing, packaging, automotive (for example for the installation of logos, lettering, interior soundproofing, interior trim, bonding in the passenger compartment) or construction (for example for sound and thermal insulation, window assembly). They can be shaped according to their final application, for example in the form of tapes, such as tapes for industrial use, DIY tapes or for use on construction sites, single or double-sided tapes, or in the form of labels, bandages, plasters, patches or graphic films.

[0096] According to one embodiment, the self-adhesive article is a self-adhesive multi-layer system, and in particular a self-adhesive label or tape, which may be single- or double-sided.

[0097] The material that can be used for the support layer can, for example, be any type of rigid or flexible support. Examples include foam, felt, non-woven supports, plastics, membranes, papers or a film of a polymer material with one or more layers, in particular a non-stick protective paper or plastic film.

[0098] The support layer is made of a material chosen, for example, from polyolefins, such as polyethylene, including high-density polyethylene, low-density polyethylene, linear low-density polyethylene and linear ultra-low-density polyethylene, polypropylene and polybutylenes; polystyrene; natural or synthetic rubber; vinyl copolymers, such as polyvinyl chloride, plasticized or unplasticized, and poly(vinyl acetate); olefin copolymers, such as ethylene / methacrylate copolymers, ethylene / vinyl acetate copolymers, acrylonitrile / butadiene / styrene copolymers, and ethylene / propylene copolymers; acrylic polymers and copolymers; polyurethanes; polyethers; polyesters; and mixtures thereof.Preferably, the support layer is based on acrylic polymers, Polyethylene (PE), oriented, non-oriented or bi-oriented Polypropylene (PP), Polyimide, Polyurethane, Polyester such as Polyethylene terephthalate (PET), or paper.

[0099] According to one embodiment, the self-adhesive article obtained from the adhesive composition according to the invention comprises a permanent support layer coated with an adhesive layer. Preferably, the adhesive layer is further coated with a non-stick protective plastic film or paper, preferably silicone-coated.

[0100] According to another embodiment, the self-adhesive article obtained from the adhesive composition according to the invention comprises a non-permanent support layer which is made up of a first non-stick plastic film or protective paper, preferably silicone-coated, said layer being coated with an adhesive layer, itself also being able to be coated with a second non-stick plastic film or protective paper. This embodiment is particularly suitable for the assembly by gluing of windows, more particularly for the assembly of the rigid panel made up of double or triple glazing with the window frame.According to this embodiment, said non-permanent support layer is intended to be removed by the user at the time of implementation of the self-adhesive article for the purpose of assembling the window, so as to reveal the single crosslinked adhesive layer, the mechanical properties of which, in particular resistance to rupture, are, in accordance with the invention, particularly improved.

[0101] As an alternative to the release liner, the back of the permanent carrier layer, which is not coated with the adhesive layer, may have a release surface, for example a silicone release liner.

[0102] According to another embodiment, the permanent support layer is coated on both sides with an adhesive composition, which may be identical or different, at least one of the two adhesive compositions being according to the invention, advantageously leading to the manufacture of so-called double-sided tapes.

[0103] Preferably, the support layer has a thickness ranging from 10 micrometers to 50 mm, more preferably ranging from 10 micrometers to 20 mm, more preferably ranging from 20 micrometers to 10 mm, more preferably ranging from 20 micrometers to 1 mm.

[0104] In certain specific cases, it is necessary to carry out a surface treatment of the support layer to increase the adhesion of the adhesive layer during the coating step on it.

[0105] The self-adhesive article according to the invention can thus bond two substrates. The substrate on which the self-adhesive article is intended to be applied (referred to as the “substrate to be bonded”) can be flexible or rigid. In particular, it can have the same flexibility properties as the support layer described above, so as to be wound and packaged in the form of a reel, for example as described above.

[0106] Alternatively, the substrate to be bonded may be rigid. In this case, the substrate cannot be wound and packaged in the form of a reel, for example as described above. The substrate to be bonded may, for example, be chosen from concrete, paper, polyolefin substrates, glass, ceramics and metals, in particular aluminum.

[0107] The self-adhesive layer, which consists of the adhesive composition according to the invention in the crosslinked state, and which covers the support layer, in the self-adhesive article according to the invention can have a very variable thickness, ranging from 10 µm to 5000 µm, preferably.

[0108] A thickness ranging from 10 µm to 100 µm, preferably from 20 µm to 50 µm is more particularly preferred in the case of self-adhesive labels; while a thickness ranging in a much wider range from 3 µm to 5000 µm can be encountered for self-adhesive tapes.

[0109] According to one embodiment, the self-adhesive article further comprises a protective release liner.

[0110] According to one embodiment, said anti-adhesive layer is applied to the adhesive layer, after crosslinking of the adhesive composition.

[0111] The backing layer can be covered on the one of its two sides which is not coated with the adhesive layer, with a non-stick protective layer, for example with a silicone film. In this way, the self-adhesive article can be rolled up on itself and then unrolled without problem thanks to the absence of adhesion of the adhesive layer to the silicone side. Manufacturing process of the self-adhesive article :

[0112] The present invention also relates to a method for manufacturing the self-adhesive article as defined above, said method being characterized in that it comprises: (a) applying said composition by coating on a carrier surface; (b) crosslinking said composition, by heating to a temperature ranging from 15°C to 200°C; then (c) laminating or transferring the crosslinked adhesive composition layer onto a support layer or onto a non-stick protective film.

[0113] For the purposes of the present invention, the term "carrying surface" means either a belt conveyor covered with a non-stick layer, or a non-stick protective film ("release liner" in English), or a support layer.

[0114] In the case where the carrier surface is a non-stick protective film, the method of manufacturing the self-adhesive article according to the invention may comprise step (c) of transferring the crosslinked adhesive layer onto a support layer.

[0115] In the case where the carrier surface is a support layer or a non-stick protective film, the method of manufacturing the self-adhesive article according to the invention may also comprise step (c) of laminating the adhesive layer onto a non-stick protective film.

[0116] According to a preferred variant of the invention, step (c) of the above-described method consists of transferring the crosslinked adhesive layer onto a flexible support layer (which may be a plastic film), where appropriate after cooling the crosslinked adhesive layer to a temperature below the degradation or softening temperature of the material making up the support layer.

[0117] According to one embodiment, the method for manufacturing the self-adhesive article according to the invention further comprises a step (d) of coating a second layer of adhesive composition according to the invention on the support layer, followed by a step (e) of crosslinking the adhesive composition coated in step (d) by heating to a temperature ranging from 15°C to 200°C, preferably from 15°C to 45°C, preferably at room temperature, in particular between 18°C ​​and 25°C, in particular at 23°C. According to this embodiment, a double-sided self-adhesive article is obtained.

[0118] The coating step (a) can be carried out using known coating devices, such as for example a lip or curtain nozzle, or even a roller. It uses a grammage of adhesive composition which can range from 3 g / m 2 < to 5000 g / m 2 < , in particular from 10 g / m 2 < to 5000 g / m 2 < .

[0119] The grammage of adhesive composition required for the manufacture of self-adhesive labels may range from 10 g / m 2 to 100 g / m 2 , preferably from 20 g / m 2 to 50 g / m 2 . That required for the manufacture of self-adhesive tapes may vary in a much wider range from 3 g / m 2 to 5000 g / m 2 , preferably from 15 g / m 2 to 250 g / m 2 per side.

[0120] Crosslinking step (b) is, according to a preferred variant of the invention, carried out at a temperature ranging from 15°C to 45°C, preferably at room temperature, in particular between 18°C ​​and 25°C, in particular at 23°C.

[0121] According to one embodiment, the coated adhesive composition is further subjected, during crosslinking step (b), to treatment in a humid atmosphere characterized by its humidity level and, in particular, in a gaseous environment where water molecules are present between 10 and 200 g per m 3 of gas.

[0122] Preferably, the humid atmosphere is an atmosphere in which from 2 to 100% of the molecules are water molecules, preferably from 3 to 50%, more preferably from 3 to 10% of the molecules are water molecules.

[0123] Humidity is expressed as the percentage of water per unit volume, which is the number of water molecules divided by the total number of molecules in a unit volume. Due to the linear nature of this scale, humidity is easily measured and controlled using, for example, PID ("Proportional-Integral-Derivative") monitors. The weight percentage can be calculated by multiplying the percentage of water molecules to the total number of molecules by a factor of 0.622. General information on humidity in various environments is described by W. Wagner et al., in "International Steam Tables - Properties of Water and Steam based on the Industrial Formulation IAPWS-IF97 ".

[0124] Crosslinking step (b) is, according to a further preferred variant of the invention, carried out without humidity control, particularly at the humidity of the ambient atmosphere, in particular at an absolute humidity of 20 to 60 g of water per m 3< of air, preferably 40 to 60 g / m 3< .

[0125] This crosslinking step (b) has the effect in particular of creating - between the polymer chains with a hydrolyzable alkoxysilane end group of the adhesive composition and under the action of atmospheric humidity - siloxane-type bonds which lead to the formation of a three-dimensional polymer network. The adhesive composition thus crosslinked is in particular a pressure-sensitive adhesive which gives the support layer coated with it the desirable adhesive power and tack.

[0126] Preferably, the coating is carried out uniformly on the support layer or on the anti-adhesive protective layer but the coating can also be adapted to the desired shape of the final self-adhesive article.

[0127] According to one embodiment, the coating with the adhesive composition is carried out on at least a portion of both sides of the support layer. If both sides of the support layer are coated, the adhesive composition may be identical or different on both sides, and the grammage may be identical or different on both sides.

[0128] According to one embodiment of the invention, the self-adhesive article comprises an adhesive layer on at least a portion of one face or on at least a portion of both faces of the support layer, said adhesive layer(s) optionally being coated with a non-stick protective layer. According to one embodiment, the self-adhesive article comprises two non-stick protective layers on each of the two adhesive layers. In this case, the two protective layers may be made of identical or different materials and / or they may have an identical or different thickness.

[0129] The present invention finally relates to a bonding method using the self-adhesive article, as defined above, characterized in that it comprises the following steps: (a) removing the protective release layer, where such a layer is present; (b) applying the self-adhesive article to a surface of a product; and (c) applying pressure to the article.

[0130] In step b), the self-adhesive article is applied so that the self-adhesive part of the article (formed by the self-adhesive layer) faces the surface of the product.

[0131] According to an embodiment in which the self-adhesive article is a double-sided article, the bonding method further comprises a step in which either a second surface of a product is applied to the article bonded to the first surface of a product, or the article bonded to the first surface of a product is applied to a second surface of a product.

[0132] The following examples are given purely for illustrative purposes of the invention and should not be interpreted to limit its scope. Example A (comparison according to WO 2020 / 128200): Heat-crosslinkable adhesive composition based on GENIOSIL ®< STP-E30 A1. Preparation of the composition :

[0133] The composition shown in Table 1 is prepared by first introducing the Picco ®< AR100 tackifying resin into a glass reactor under vacuum and heated to approximately 160°C. Then, once the resin is well melted, the GENIOSIL ®< STP-E30 is added.

[0134] The mixture is stirred under vacuum for 15 minutes, then cooled to 70°C. The catalyst (K-KAT ®< 5218) and the silsesquioxane DOW CORNING ®< 3074 are then introduced. The mixture is kept under vacuum and stirred for a further 10 minutes. A2. Measurement of crosslinking time at room temperature :

[0135] The composition of example A is applied so as to fill a mold corresponding to a type H2 test piece, as defined by standard NF T46-002, whose thickness is 4 mm and whose central part has a rectangular section of 4 x 2 mm over a length of 25 mm.

[0136] The mold is left at room temperature (approximately 23°C) and the behavior of the composition is observed. The time required for total crosslinking is 24 hours. A3. Measurement of stress and elongation at break by tensile test :

[0137] The principle of the measurement consists of stretching in a tensile machine, the movable jaw of which moves at a constant speed equal to 100 mm / minute, a type H2 test piece, as defined above, made of the crosslinked adhesive composition and recording, at the moment when the test piece ruptures, the applied stress (in MPa) as well as the elongation of the test piece or elongation (in %).

[0138] The results of the measurements obtained are shown in Table 1. A4. Preparation of a PET support layer coated with the crosslinked composition, at a grammage equal to 60 g / m 2< :

[0139] A rectangular sheet of PolyEthylene Terephthalate (PET) with a thickness of 50 µm and dimensions of 20 cm by 40 cm is used as the support layer.

[0140] The composition obtained at point A1 is preheated to a temperature close to 100°C and introduced into a cartridge from which a bead is extruded which is deposited near the edge of the sheet parallel to its width.

[0141] The composition contained in this bead is then distributed over the entire surface of the sheet, so as to obtain a uniform layer of substantially constant thickness. This is done using a film puller (also called a filmograph) which is moved from the edge of the sheet to the opposite edge. This deposits a layer of composition corresponding to a weight of 60 g / m 2< , which represents a thickness of approximately 60 µm.

[0142] The coated PET sheet is then placed in an oven at 120°C and in a humid atmosphere (4% relative humidity) for 5 minutes to crosslink the composition, then laminated onto a protective non-stick layer consisting of a rectangular silicone film sheet of the same dimensions.

[0143] The resulting three-layer is subjected to the tests described below. A4.1 Peeling at room temperature :

[0144] The adhesive strength is assessed by the 180° peel test on a stainless steel plate as described in FINAT method no. 1, published in the FINAT Technical Manual 6th edition, 2001. FINAT is the international federation of manufacturers and converters of self-adhesive labels. The principle of this test is as follows.

[0145] A test piece in the form of a rectangular strip (2.54 cm x 15 cm) is cut from the three-layer obtained previously.

[0146] This test piece is kept at room temperature (approximately 23°C and 50% humidity) for 7 hours. Then, after removing the corresponding portion of the protective anti-adhesive layer, it is fixed over 2 / 3 of its length on a substrate made of a stainless steel plate.

[0147] The resulting assembly is left for 20 minutes at room temperature (approximately 23°C). It is then placed in a traction device capable, from the remaining free end of the rectangular strip, of peeling or detaching the strip at an angle of 180° and with a separation speed of 300 mm per minute. The device measures the force required to detach the strip under these conditions.

[0148] The corresponding result is expressed in N / 2.54 cm and shown in Table 1. A4.2 Peeling after 7 days of storage at 50°C:

[0149] The previous test is repeated, except that after cutting the specimen into a rectangular strip, it is stored for 7 days at a temperature of 50°C and in an atmosphere of 50% humidity, before being fixed to the stainless steel plate.

[0150] The corresponding result is expressed in N / 2.54 cm and shown in Table 1. A4.3 Instant membership (also called loop testing):

[0151] Immediate tack is assessed by the instant adhesion test known as the loop test, described in FINAT method no. 9, the principle of which is as follows.

[0152] A test piece in the form of a rectangular strip (25 mm x 175 mm) is cut from the PET support layer coated with the crosslinked composition obtained previously.

[0153] After removing all of the protective anti-adhesive layer, the 2 ends of this strip are joined to form a loop with the adhesive layer facing outwards. The 2 joined ends are placed in the movable jaw of a traction device capable of imposing a movement speed of 300 mm / minute along a vertical axis with the possibility of going back and forth. The lower part of the loop placed in a vertical position is first brought into contact with a horizontal glass plate of 25 mm by 30 mm on a square area of ​​approximately 25 mm on each side. As soon as this contact is made, the direction of movement of the jaw is reversed. The immediate adhesive power is the maximum value of the force necessary for the loop to completely detach from the plate.

[0154] The result is expressed in N / (2.54 cm) 2< and is shown in Table 1. A4.4 Shear strength time at 125°C :

[0155] The high temperature maintenance of the adhesive power of the previously obtained PET support layer is evaluated by a test which determines the resistance time of the adhesive joint to static shear at 125°C. Reference is made for this test to FINAT method no. 8. The principle is as follows.

[0156] A test piece in the form of a rectangular strip (25 mm x 75 mm) is cut from the three-layer obtained previously and is stored at room temperature (23°C, 50% humidity) for 24 hours.

[0157] After removing all of the protective anti-adhesive layer, a 25 mm square portion located at the end of the adhesive strip is fixed to a glass plate.

[0158] The test plate thus obtained is introduced, by means of a suitable support, in a substantially vertical position into an oven at 125°C, the unbonded part of the 50 mm long strip being located below the plate. After thermal equilibration, the remaining free part of the strip is connected to a mass of 1 kg, the entire device remaining in the oven at 125°C throughout the test.

[0159] Under the effect of this mass, the adhesive joint which ensures the fixing of the strip on the plate is subjected to a shear stress. To better control this stress, the test plate is in fact placed so as to make an angle of 2° with respect to the vertical.

[0160] The time after which the strip detaches from the plate following the rupture of the glue joint under the effect of this stress is noted.

[0161] The result, expressed in hours, is shown in Table 1. A4. 5 Shear strength time at 125°C after 7 days of storage of the specimen at 50°C :

[0162] The previous test is repeated, except that after cutting the test piece into a rectangular strip, it is stored for 7 days at a temperature of 50°C and in an atmosphere of 50% humidity, before being fixed on the glass plate.

[0163] The result, expressed in hours, is shown in Table 1. Examples B etc : Comparative adhesive compositions based on GENIOSIL ®< STP-E30

[0164] The preparation of the composition of Example A is repeated as indicated in point A1, except that: for example B: no silsesquioxane is introduced, for example C: no silsesquioxane is introduced, and after adding the catalyst and then stirring for 10 minutes, AEROSIL ®< R202 is introduced, and stirring is carried out again for approximately 10 minutes.

[0165] The measurement of the curing time at room temperature, as well as the tensile and shear strength tests at 125°C, are repeated as indicated in points A2, A3 and A4. The results shown in Table 1 are obtained. Examples 1 and 2 according to l'invention : Room temperature crosslinkable adhesive compositions based on GENIOSIL ®< STP-E30

[0166] The preparation of the composition of Example A is repeated as indicated in point A1, except that, after adding the catalyst and the silsesquioxane and then stirring for 10 minutes, the AEROSIL ®< R202 is introduced, and stirring is carried out again for approximately 10 minutes.

[0167] The measurement of the curing time at room temperature and the tensile test are repeated as indicated in points A2 and A3. The results shown in Table 1 are obtained. It is observed for Example 2 that the curing time at room temperature is, compared to Example B, considerably reduced (by more than a factor of 2). Furthermore, it is observed for Example 2 that the breaking stress is significantly increased compared to Example B. However, the separate addition of silsesquioxane resin (E) or fumed silica (C) leads to a reduction in the breaking stress (Examples A and C). The increase in the breaking stress observed for the addition of a combination of silsesquioxane resin (E) and fumed silica (C) is therefore completely unexpected and demonstrates a synergy between these ingredients.

[0168] The preparation of the self-adhesive PET support layer is also repeated as indicated in point A4., except that the coated PET sheet is left at room temperature (approximately 23°C) for 7 hours for crosslinking, before being laminated onto the protective release layer. The resulting trilayer is then subjected to the tests described in points A4.1 to A4.5 which lead to the results indicated in Table 1.

[0169] For examples 1 and 2, peel results (at room temperature or after storage for 7 days at 50°C) are observed that are substantially identical to those of example A.

[0170] The instant adhesion (or tack) values ​​obtained for these two examples are, although lower than those of example A, entirely appropriate for a self-adhesive support.

[0171] Finally, the results show that the addition of silsesquioxane resin (E) (example A) leads to an improvement in shear strength at 125°C (comparison with example B), while the addition of fumed silica (C) (example C) has almost no effect on the shear strength at 125°C. In contrast, the shear strength values ​​at 125°C measured for the self-adhesive PET layers of examples 1 and 2 demonstrate a much higher temperature cohesion than examples A, B and C. Thus, the addition of a combination of silsesquioxane resin (E) and fumed silica (C) allows a surprising improvement in the shear strength at 125°C, these ingredients acting in synergy. Furthermore, the self-adhesive PET layers of Examples 1 and 2 retain these shear strength properties at 125°C even after storage for 7 days at 50°C. Table 1 Ingredient Content in % weight / weight Example A Example B Example C Example 1 Example 2 (A) GENIOSIL ®< STP-E30 42,4 44,7 42,4 40,84 40,19 (B) Picco ®< AR100 51,6 54,3 51,6 49,71 48,94 (C) AEROSIL ®< R202 - - 5 3,5 5,0 (D) K-KAT ®< 5218 1 1 1 0,98 0,98 (E) DOW CORNING ®< 3074 5 - - 4,97 4,89 Curing time at room temperature (hours) 24 18 5,67 ND 7 Room temperature peel (N / 2.54 cm) 19 ND ND 21 20 Peeling after 7 days at 50°C (N / 2.54 cm) 22 ND ND 21 20 Instant adhesion (N / (2.54 cm) 2< ) 36 ND ND 23 18 Shear strength time at 125°C (hours) 24 16 15,5 70 40 Shear strength time at 125°C after 7 days at 50°C (hours) 25 ND ND 70 42 breaking stress (in MPa) 0,16 0,28 0,11 ND 0,39 elongation at break (in %) 326 ND ND ND 300 ND = Not Determined

Claims

1. A self-adhesive article comprising a support layer coated with a self-adhesive layer, characterized in that said self-adhesive layer consists of a crosslinkable adhesive composition, in the crosslinked state, the crosslinkable adhesive composition being characterized in that it comprises: - at least one polymer (A) comprising a hydrolyzable alkoxysilane group; - at least one tackifying resin (B); - at least one pyrogenic silica (C); - at least one crosslinking catalyst (D); and - a silsesquioxane resin (E).

2. The self-adhesive article as claimed in claim 1, characterized in that the polymer (A) comprises at least one, and preferably at least two, hydrolyzable groups of formula (I):         -Si(R4)p(OR5)3-p     (I) in which: - R4 represents a linear or branched alkyl radical comprising from 1 to 4 carbon atoms, with the possibility that, when there are several R4 radicals, these radicals are identical or different; - R5 represents a linear or branched alkyl radical comprising from 1 to 4 carbon atoms, with the possibility that, when there are several R5 radicals, these radicals are identical or different, with the possibility that two OR5 groups can participate in one and the same ring; and - p is an integer equal to 0, 1 or 2, preferably equal to 0 or 1.

3. The self-adhesive article as claimed in claim 2, characterized in that the polymer (A) corresponds to one of the formulae (II), (III) or (IV): in which: - P represents a saturated or unsaturated, linear or branched, polymeric radical optionally comprising one or more heteroatoms, such as oxygen, nitrogen, sulfur or silicon, and preferably exhibiting a number-average molar mass ranging from 100 g / mol to 48 600 g / mol, more particularly from 300 g / mol to 18 600 g / mol or also from 500 g / mol to 12 600 g / mol, - R1 represents a divalent hydrocarbon radical comprising from 5 to 15 carbon atoms which can be aromatic or aliphatic, linear, branched or cyclic, - R3 represents a linear or branched divalent alkylene radical comprising from 1 to 6 carbon atoms, preferably from 1 to 3 carbon atoms, - X represents a divalent radical chosen from -NH-, -NR7- or -S-, - R7 represents a linear or branched alkyl radical comprising from 1 to 20 carbon atoms and which can also comprise one or more heteroatoms, and - f is an integer ranging from 1 to 6, preferably ranging from 2 to 5, preferably ranging from 2 to 4, more preferably ranging from 2 to 3.

4. The self-adhesive article as claimed in claim 3, characterized in that the polymer (A) corresponds to one of the formulae (II'), (III') or (IV'): in which: - R2 represents a saturated or unsaturated, linear or branched, divalent hydrocarbon radical optionally comprising one or more heteroatoms, such as oxygen, nitrogen, sulfur or silicon, and preferably exhibiting a number-average molar mass ranging from 100 g / mol to 48 600 g / mol, more particularly from 300 g / mol to 18 600 g / mol or also from 500 g / mol to 12 600 g / mol, and - n is an integer greater than or equal to 0.

5. The self-adhesive article as claimed in one of claims 1 to 4, characterized in that the tackifying resin (B) is chosen from: - (i) resins obtained by polymerization of terpene hydrocarbons and of phenols, in the presence of Friedel-Crafts catalysts; - (ii) resins obtained by a process comprising the polymerization of α-methylstyrene, it also being possible for said process to comprise a reaction with phenols; - (iii) rosins of natural origin or modified rosins (such as, for example, the rosin extracted from pine gum, wood rosin extracted from tree roots and their derivatives which are hydrogenated, dimerized, polymerized or esterified with monoalcohols or polyols, such as glycerol or pentaerythritol); - (iv) resins obtained by hydrogenation, polymerization or copolymerization (with an aromatic hydrocarbon) of mixtures of unsaturated aliphatic hydrocarbons having approximately 5, 9 or 10 carbon atoms resulting from petroleum fractions; - (v) terpene resins (which generally result from the polymerization of terpene hydrocarbons, such as, for example, monoterpene (or pinene), in the presence of Friedel-Crafts catalysts); - (vi) copolymers based on natural terpenes (such as, for example, styrene / terpene, α-methylstyrene / terpene and vinyltoluene / terpene); or else - (vii) acrylic resins having a viscosity at 100°C of less than 100 Pa.s.

6. The self-adhesive article as claimed in one of claims 1 to 5, characterized in that the pyrogenic silica (C) is hydrophobic.

7. The self-adhesive article as claimed in claim 6, characterized in that the hydrophobic pyrogenic silica (C) is obtained by treatment of a pyrogenic silica with a polydimethylsiloxane.

8. The self-adhesive article as claimed in one of claims 1 to 7, characterized in that the pyrogenic silica (C) has a BET specific surface of at least 10 m2 / g, preferably ranging from 50 to 400 m2 / g.

9. The self-adhesive article as claimed in one of claims 1 to 8, characterized in that the silsesquioxane resin (E) corresponds to the following general formula (V): in which each of R'1 to R'8 represents, independently of one another, a group chosen from: - a hydrogen atom, - a radical chosen from the group consisting of a linear or branched C1-C4 alkoxy radical, a linear or branched alkyl radical comprising from 1 to 30 carbon atoms, an alkenyl radical comprising from 2 to 30 carbon atoms, an aromatic radical comprising from 6 to 30 carbon atoms, an allyl radical comprising from 3 to 30 carbon atoms, a cyclic aliphatic radical comprising from 3 to 30 carbon atoms and an acyl radical comprising from 1 to 30 carbon atoms, and - an -OSiR'9R'10 group in which R'9 and R'10 each represents, independently of each other, a hydrogen atom or a radical chosen from the group consisting of linear or branched C1-C4 alkyls, linear or branched C1-C4 alkoxys, C2-C4 alkenyls, a phenyl, a C3-C6 allyl radical, a cyclic C3-C8 aliphatic radical and a C1-C4 acyl radical; provided: - that at least one radical among the R'1 to R'8 radicals is a C1-C4 alkoxy radical; and - that at least one radical among the R'1 to R'8 radicals is a phenyl radical.

10. The self-adhesive article as claimed in one of claims 1 to 9, characterized in that the adhesive composition comprises: - from 3% to 90% by weight of at least one polymer (A); - from 8% to 80% by weight of at least one tackifying resin (B); - from 1% to 10% by weight of the pyrogenic silica (C); - from 0.01% to 10% by weight of crosslinking catalyst (D); and - from 0.1% to 20% by weight of silsesquioxane resin (E); these percentages by weight being indicated on the basis of the total weight of said composition.

11. A process for the manufacture of the self-adhesive article as defined in one of claims 1 to 10, characterized in that it comprises: - (a) the application of said composition by coating onto a carrying surface; - (b) the crosslinking of said composition, by heating at a temperature ranging from 15°C to 200°C; and then - (c) the lamination or the transfer of the layer of crosslinked adhesive composition onto a support layer or onto a nonstick protective film.

12. The process for the manufacture of the self-adhesive article as claimed in claim 11, characterized in that the crosslinking stage b) is carried out at a temperature ranging from 15°C to 45°C, preferably at ambient temperature, especially between 18°C and 25°C, in particular at 23°C.

13. An adhesive bonding method employing the self-adhesive article as defined in one of claims 1 to 10, characterized in that it comprises the following stages: a) the removal of the nonstick protective layer, when such a layer is present; b) the application of the self-adhesive article to a surface of a product; and c) the application of a pressure to said article.