SELF-ADHESIVE MULTI-LAYER ARTICLE AND METHOD FOR MANUFACTURING SAME

Description

[0001] The field of the invention is that of self-adhesive multilayer articles and their manufacturing methods and more particularly self-adhesive multilayer articles in which a crosslinked or polymerized silicone matrix is ​​associated with an adhesive.

[0002] A typical self-adhesive multi-layer article structure comprises a laminate of a front carrier material, an adhesive layer, most often a pressure-sensitive adhesive layer, and a back carrier material made non-stick by coating with a specific coating.

[0003] The front support can be of a wide variety of materials, but is usually made of paper or plastic. The non-stick backing material allows the adhesive portion to be peeled off the backing. This is particularly useful for labels, tapes, or other self-adhesive devices.

[0004] For the backing, a coating, most often a silicone matrix, is applied to the surface of a support and then crosslinked so as to make it non-stick to the adhesive. Thus, the two main components are: the carrier material, which is most often in the form of paper or plastic film. It physically supports, at the beginning and after, the process of applying and forming a uniform layer of material with non-stick properties. For economic reasons, the amount of coated material must be minimized and this condition is achievable with a substrate that keeps most of the coated material, and the non-stick coating, on the surface. It provides very low surface free energy, almost entirely dispersive in nature, on the coated side. Crosslinked silicone elastomer is the universally used material for creating a layer with the required non-stick properties.

[0005] The role of the backing is to support the self-adhesive multi-layer article itself during its production and to protect the adhesive layer from impurities, so that it can pass through transformation processes such as, for example, when it comes to a label: printing, cutting, trimming, perforation, etc.

[0006] The adhesive used in this type of product is most often a pressure-sensitive adhesive (also called self-adhesive glue or, in English, "Pressure Sensitive Adhesive" or PSA) which gives the support coated with it an immediate sticking power at room temperature (often referred to as "tack"), which allows its instant adhesion to a substrate under the effect of light and brief pressure.

[0007] These self-adhesive multilayer articles can be prepared according to a so-called "in-line" process which involves the successive steps comprising in particular the deposition of a crosslinkable and / or polymerizable organopolysiloxane composition on a support-type material, its crosslinking and / or polymerization by supplying energy so as to form a non-stick silicone coating, the application to this coating of an adhesive generally in the form of an aqueous emulsion, the drying of this emulsion and the application of a second support. In practice, the deposition rate of a crosslinkable and / or polymerizable organopolysiloxane composition is between 0.1 and 5 g / m 2 < which corresponds to thicknesses of the order of a micrometer for 1 g / m 2 < .

[0008] The self-adhesive multi-layer article thus formed is then generally stored for a more or less extended period on reels. This type of self-adhesive multi-layer article is particularly used for the production of adhesive protective papers such as labels, decorative papers and adhesive tapes. 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 then be stored and transported.

[0009] Silicone release coatings based on curable silicone, particularly radiation-curable silicones, for releasing pressure-sensitive adhesives are therefore well known. In the 1980s, two radiation-curable silicone systems appeared on the market. One system was an acrylate / silicone copolymer system curable by a free-radical mechanism under irradiation with both ultraviolet rays and electron beams. These systems are described, for example, in U.S. Pat. Nos. 4,201,808; 4,568,566; 4,678,846; 5,494,979; 5,510,190; 5,552,506; 5,804,301; 5,891,530 and 5,977,282.

[0010] The other system was an ultraviolet-curable system, curing by a cationic mechanism and based on epoxy-functional silicone polymers. Epoxy-functional silicone polymer systems are described, for example, in U.S. Pat. Nos. 4,421,904; 4,547,431; 4,952,657; 5,217,805; 5,279,860; 5,310,601; 5,340,898; 5,360,833; 5,650,453; 5,866,264 and 5,973,020.

[0011] Given industrial coating rates, the crosslinking kinetics must be very rapid to lead to correct crosslinking, i.e. the layer made of a non-stick silicone elastomer must be sufficiently crosslinked to be able to best fulfill its non-stick function and possess the desirable mechanical qualities. The assessment of the quality of the crosslinking of the non-stick silicone layer can in particular be done through the dosage of non-crosslinked extractable compounds, the quantity of which must be as small as possible. For example, the extractable content is preferably less than 8%, under normal industrial crosslinking conditions.

[0012] The non-stick properties of the free external face of the silicone coating are expressed through the peeling force, which must be low and controlled, for the element intended to be placed on the support coated with the layer consisting of a non-stick silicone elastomer. Conventionally, this element can be the adhesive face of a label or a ribbon of the same name.

[0013] Thus, in addition to this low and controlled non-stick properties, the adhesion of the silicone coating to its support must be very high. This adhesion property is assessed, for example, using the "rub off" trade test, which consists of rubbing the surface of the coating with the finger and measuring the number of successive passes that lead to degradation of the coating.

[0014] Backings coated with a non-stick silicone film can be, for example: a paper or a polymer film for protecting the adhesive side of a pressure-sensitive adhesive or self-adhesive element; or a polymer film of the polyolefin type (polyvinyl chloride (PVC), Polypropylene or Polyethylene) or of the polyester type).

[0015] Curable, non-stick silicone compositions are applied to such substrates to facilitate the removal of adhesive materials reversibly laminated to these substrates. Formulations that can be crosslinked by radical polymerization can be used. They mainly consist of an acrylate-functionalized polyorganosiloxane and a photoinitiator.

[0016] Free radical photoinitiators include aromatic ketones which, after exposure to ultraviolet (UV) radiation: undergo homolytic cleavage at the α position of the carbonyl function with the formation of two radical fragments, one of which is a benzoyl radical (type I photoinitiators), or form free radicals when promoted into their excited states by hydrogen abstraction from a hydrogen donor molecule (more commonly referred to as a "co-initiator") which leads to the formation of an inactive ketyl radical and an initiating radical from the corresponding donor (type II photoinitiators).

[0017] Examples of type II photoinitiators include isopropylthioxanthone (ITX), benzophenone, and camphorquinone (CQ). Examples of coinitiators include phenyltetrazolethiol, tris(trimethylsilyl)silane, and aromatic amines such as ethyldimethylaminobenzoate (EDB).

[0018] Examples of type I photoinitiators include: α-hydroxyketones, benzoin ethers, α-amino aromatic ketones.

[0019] As prior art, we can cite the granted patents FR2632960, EP0940422-B1, EP0979851-B1 and EP1544232-B1. Thus, said patents describe the use of (meth)acrylate functionalized polysiloxanes as non-stick coating agents that can harden under the effect of radiation. The photoinitiator conventionally used is Irgacure ®< 1173 (formerly Darocur ®< 1173) from BASF. The photoinitiator Tego ®< A17 or its successor Tego ®< A18 from Evonik is used for silicone non-stick coatings as described in the RC Newsletter N°2 brochure of September 2009 published by Evonik Industries.

[0020] The most widely used photoinitiators have the disadvantage of releasing suspected CMR benzaldehyde and / or highly flammable isopropanol during polymerization and / or crosslinking under ultraviolet radiation.

[0021] Furthermore, document EP006705 discloses a silicone composition for non-stick coating crosslinkable by ionizing or non-ionizing actinic radiation, a method for producing a non-stick silicone coated article, a non-stick coated article and a laminate.

[0022] The subject of the present invention is distinguished from this document by a silicone composition comprising at least one acrylate-functionalized silicone oil and a photoinitiator from the family of acylphosphine oxide derivatives. The effects brought about by these distinctive characteristics are in particular the absence of release of undesired compounds such as benzaldehyde or isopropanol, and the obtaining of a multilayer article with a non-stick silicone coating having optimal smear, optimal rub off, the absence of dewetting and a satisfactory extractables level.

[0023] WO2013 / 013568 relates to organic adhesives based on acrylic monomers with good transparency and non-yellowing properties. This document is silent on the properties of non-stick silicone coatings (smear, rub-off, dewetting and extractables content) and on the non-stick properties of a multi-layer article.

[0024] For all these reasons, self-adhesive multi-layer articles using non-stick silicone coatings by radical polymerization must be constantly improved.

[0025] In this context, the first essential objective of the present invention is to develop a self-adhesive multilayer article comprising a non-stick silicone coating which does not use photoinitiators which are likely to easily transform into a toxic or flammable product and in particular to release benzaldehyde or isopropanol. It is desired to obtain coated substrates which do not present toxicity problems.

[0026] The second essential objective of the present invention is to provide a self-adhesive multilayer article using a non-stick silicone coating which has optimal properties in terms of extractable rate, adhesion to the support and non-adhesion with respect to an adhesive.

[0027] Another essential objective of this invention is to provide a method for preparing a self-adhesive multilayer article according to the invention.

[0028] Another objective of this invention is to provide a silicone composition which is a precursor to a non-stick silicone coating in accordance with the invention and which can be used in a self-adhesive multi-layer article.

[0029] The last objective of the invention concerns the use of the objects in accordance with the invention in key fields of industry.

[0030] All these objectives, among others, are achieved by the present invention which relates to a self-adhesive multilayer article comprising: 1) a back support DO having a top face SI1 and a bottom face SI2, 2) at least one layer of non-stick silicone coating RC applied to the top face SI1 back support DO and which is prepared by irradiation of a curable silicone composition C not containing a solvent and comprising as constituents: a) at least one functionalized organopolysiloxane A comprising: a1) at least one formula unit (I) next: R a Z b SiO (4-ab) / 2 (I)formula in which: the symbols R, identical or different, each represent a linear or branched C 1 to C 18 alkyl group, a C 6 to C 12 aryl or aralkyl group, optionally substituted, preferably by halogen atoms, or an alkoxy radical -OR 4< with R 4< being a hydrogen atom or a hydrocarbon radical comprising from 1 to 10 carbon atoms, the symbols Z are monovalent radicals of formula -y-(Y') n in which: y represents a polyvalent linear or branched C 1 -C 18 alkylene radical optionally extended by bivalent C 1 to C 4 oxyalkylene or polyoxyalkylene radicals optionally substituted by a hydroxy radical, Y' represents a monovalent alkenylcarbonyloxy radical, and n is equal to 1, 2 or 3, and a is an integer equal to 0, 1 or 2, b is an integer equal to 1 or 2 and the sum a+b= 1, 2 or 3; and a2) possibly patterns of formula (II) next: R a SiO (4-a) / 2 (II)formula in which: the symbols R, identical or different, each represent a linear or branched C 1 to C 18 alkyl group, a C 6 to C 12 aryl or aralkyl group, optionally substituted, preferably by halogen atoms, and a is an integer equal to 0, 1, 2 or 3, and b) an effective quantity of between 0.1% and 5% by weight relative to the weight of the functionalized organosiloxane or organopolysiloxane A of at least one photoinitiator P type I of the family of acylphosphine oxide derivatives of formula (III) next: formula in which: the symbol R 5< is a monovalent radical -OR 8< with the symbol R 8< which is a hydrocarbon radical comprising from 1 to 8 carbon atoms; the symbol R 6< is a phenyl radical optionally substituted by: one or more halogen atoms, a hydrocarbon radical comprising from 1 to 8 carbon atoms, an alkoxy hydrocarbon radical comprising from 1 to 8 carbon atoms, and / or a thio hydrocarbon radical comprising from 1 to 8 carbon atoms; and the symbol R 7< represents a hydrocarbon radical comprising from 1 to 12 carbon atoms, a benzyl radical or a phenyl radical optionally substituted by one or more halogen atoms, a hydrocarbon radical comprising from 1 to 8 carbon atoms, an alkoxy hydrocarbon radical comprising from 1 to 8 carbon atoms and / or a cycloalkyl radical; 3) at least one pressure-sensitive adhesive PSA, applied on the non-stick silicone coating layer, 4) a front support FRapplied to the adhesive - PSA - component 3), and 5) possibly at least one layer of non-stick silicone coating RC applied to the underside SI2 back support DO and which is prepared by applying and irradiating said curable silicone composition C and on this same layer we find at least one pressure-sensitive adhesive PSA.

[0031] Components 5) are present in self-adhesive and double-sided articles.

[0032] In this context, the self-adhesive multi-layer article according to the invention simultaneously has the following advantages: during its preparation, there is no release of benzaldehyde or isopropanol, therefore no health and safety risks for operators or environmental risks; the silicone coating present in the article has good properties in terms of extractables, adhesion and anti-adhesion; and the self-adhesive multilayer article is durable, meaning that its properties are preserved during storage.

[0033] It is to the credit of the inventors that they have judiciously selected the constituents of the curable silicone composition. C implemented in the preparation of the article according to the invention and in particular, said photoinitiator Paccording to the invention which makes it possible to produce high-performance non-stick coatings on polymer supports, in particular polyester, for example PET. Thanks to the invention, during the preparation of the silicone non-stick layer, in particular by crosslinking under UV, neither benzaldehyde nor isopropanol are released and the coatings obtained have excellent adhesion ("rub-off"), minimized peeling force and good mechanical and physical properties.

[0034] In addition, the photoinitiator P according to the invention (acylphosphine oxide derivatives of formula (III)) has the advantage of also having an absorption band in the region of 350 to 420 nm, which makes its use very advantageous in the case of UV crosslinking via light-emitting diode lamps, or UV LED lamps which emit UV at wavelengths of 365 nm and / or 395 nm. The acronym "LED" is well known to those skilled in the art and is the abbreviation of the English term "Light-Emitting Diode".

[0035] Performance achieved through the careful choice of components of the curable silicone composition C in terms of the quality of crosslinking by radical polymerization: reactivity / level of crosslinking / kinetics, are quite interesting, as evidenced by the low rates of extractables obtained.

[0036] It should be noted that the adhesion properties on the support are all the more positive, as they last for long periods, for example at least two weeks, even under severe conditions, in particular humidity and / or temperature.

[0037] These advantageous characteristics are particularly exploitable for producing anti-adhesion coatings for polymer supports, in particular polyester, for example PET, useful as "liners" for self-adhesive labels (pressure-sensitive adhesive), presented in the form of rolls or reels of film, most often manufactured at very high speed.

[0038] This is all the more interesting since these results are obtained with a silicone composition, the rheological behavior of which is not affected by the type of photoinitiator. Indeed, depending on the needs, the viscosity of the curable silicone composition C can be modulated so that it is perfectly suitable for being coated on any support and in particular on any flexible support and that it does not release either benzaldehyde or isopropanol during crosslinking under UV.

[0039] According to a particular embodiment, the invention relates to a self-adhesive multilayer article comprising: 1) a back support DO having a top face SI1 and a bottom face SI2, 2) at least one layer of non-stick silicone coating RC applied to the top face SI1 back support DOand which is prepared by irradiation of a curable silicone composition C not containing a solvent and comprising as constituents: a) at least one functionalized organopolysiloxane A comprising: a1) at least one unit of formula (I) next: R a Z b SiO (4-ab) / 2 (I)formula in which: the symbols R, identical or different, each represent a linear or branched C 1 to C 18 alkyl group, a C 6 to C 12 aryl or aralkyl group, optionally substituted, preferably by halogen atoms, or an alkoxy radical -OR 4< with R 4< being a hydrogen atom or a hydrocarbon radical comprising from 1 to 10 carbon atoms, the symbols Z are monovalent radicals of formula -y-(Y') n in which: y represents a polyvalent linear or branched C 1 -C 18 alkylene radical optionally extended by bivalent C 1 to C 4 oxyalkylene or polyoxyalkylene radicals optionally substituted by a hydroxy radical, Y' represents a monovalent alkenylcarbonyloxy radical, and n is equal to 1, 2 or 3, and a is an integer equal to 0, 1 or 2, b is an integer equal to 1 or 2 and the sum a+b= 1, 2 or 3; and a2) possibly patterns of formula (II) next: R a SiO (4-a) / 2 (II)formula in which: the symbols R, identical or different, each represent a linear or branched C 1 to C 18 alkyl group, a C 6 to C 12 aryl or aralkyl group, optionally substituted, preferably by halogen atoms, and a is an integer equal to 0, 1, 2 or 3, and b) an effective quantity of between 0.1% and 5% by weight relative to the weight of the functionalized organosiloxane or organopolysiloxane A of at least one photoinitiator P type I of the family of acylphosphine oxide derivatives of formula (III) next: formula in which: the symbol R 5< is a monovalent radical -OR 8< with the symbol R 8< which is a hydrocarbon radical comprising from 1 to 8 carbon atoms; the symbol R 6< is a phenyl radical optionally substituted by: one or more halogen atoms, a hydrocarbon radical comprising from 1 to 8 carbon atoms, an alkoxy hydrocarbon radical comprising from 1 to 8 carbon atoms, and / or a thio hydrocarbon radical comprising from 1 to 8 carbon atoms; and the symbol R 7< represents a hydrocarbon radical comprising from 1 to 12 carbon atoms, a benzyl radical or a phenyl radical optionally substituted by one or more halogen atoms, a hydrocarbon radical comprising from 1 to 8 carbon atoms, an alkoxy hydrocarbon radical comprising from 1 to 8 carbon atoms and / or a cycloalkyl radical; 3) at least one pressure-sensitive adhesive PSA, applied on the non-stick silicone coating layer, 4) a front support FRapplied to the adhesive PSA- of component 3), and 5) at least one layer of non-stick silicone coating RC applied to the underside SI2 back support DO and which is prepared by applying and irradiating said curable silicone composition C and on this same layer we find at least one pressure-sensitive adhesive PSA.

[0040] Another subject of the invention relates to a self-adhesive multilayer article comprising: 1) a back support DO having a top face SI1 and a bottom face SI2, 2) at least one layer of non-stick silicone coating RC applied to the top face SI1 back support DO and which is prepared by irradiation of a curable silicone composition Cnot containing solvent and comprising as constituents: a) at least one functionalized organopolysiloxane A comprising: a1) at least one formula unit (I) next: R a Z b SiO (4-ab) / 2 (I)formula in which: the symbols R, identical or different, each represent a linear or branched C 1 to C 18 alkyl group, a C 6 to C 12 aryl or aralkyl group, optionally substituted, preferably by halogen atoms, or an alkoxy radical -OR 4< with R 4< being a hydrogen atom or a hydrocarbon radical comprising from 1 to 10 carbon atoms, the symbols Z are monovalent radicals of formula -y-(Y') n in which: y represents a polyvalent linear or branched C 1 -C 18 alkylene radical optionally extended by bivalent C 1 to C 4 oxyalkylene or polyoxyalkylene radicals optionally substituted by a hydroxy radical, Y' represents a monovalent alkenylcarbonyloxy radical, and n is equal to 1, 2 or 3, and a is an integer equal to 0, 1 or 2, b is an integer equal to 1 or 2 and the sum a+b= 1, 2 or 3; and a2) possibly patterns of formula (II) next: R a SiO (4-a) / 2 (II)formula in which: the symbols R, identical or different, each represent a linear or branched C 1 to C 18 alkyl group, a C 6 to C 12 aryl or aralkyl group, optionally substituted, preferably by halogen atoms, and a is an integer equal to 0, 1, 2 or 3, and b) an effective quantity of between 0.1% and 5% by weight relative to the weight of the functionalized organosiloxane or organopolysiloxane A of at least one type I photoinitiator P from the family of acylphosphine oxide derivatives of formula (III) next: formula in which: the symbol R 5< is a monovalent radical -OR 8< with the symbol R 8< which is a hydrocarbon radical comprising from 1 to 8 carbon atoms; the symbol R 6< is a phenyl radical optionally substituted by: one or more halogen atoms, a hydrocarbon radical comprising from 1 to 8 carbon atoms, an alkoxy hydrocarbon radical comprising from 1 to 8 carbon atoms, and / or a thio hydrocarbon radical comprising from 1 to 8 carbon atoms; and the symbol R 7< represents a hydrocarbon radical comprising from 1 to 12 carbon atoms, a benzyl radical or a phenyl radical optionally substituted by one or more halogen atoms, a hydrocarbon radical comprising from 1 to 8 carbon atoms, an alkoxy hydrocarbon radical comprising from 1 to 8 carbon atoms and / or a cycloalkyl radical; 3) at least one pressure-sensitive adhesive PSA, applied to the underside SI2 back support DO

[0041] The effective amount of photoinitiator P is between 0.1% and 5% by weight relative to the weight of the functionalized organosiloxane or organopolysiloxane A.

[0042] Effective examples of photoinitiators P are those described in patent application EP0007508. Preferably, the photoinitiator Pest choisi dans le groupe constitué par les dérivés (noms chimiques en anglais): 2,2-dimethyl-propionyldiphenyl- phosphine oxide, 2,2-dimethyl-heptanoyl-diphenylphosphine oxide, 2,2-dimethyl-octanoyl-diphenylphosphine oxide, 2,2- dimethyl-nonanoyl-diphenylphosphine oxide, methyl 2,2- dimethyl-octanoyl-phenylphosphinate, 2-methyl-2-ethyl hexanoyl-diphenylphosphine oxide, 1-methyl-1-cyclohexanecarbonyl-diphenylphosphine oxide, 2,6-dimethylbenzoyl-diphenylphosphine oxide, 2,6-dimethoxybenzoyl-diphenylphosphine oxide, 2,6-dichlorobenzoyl-diphenylphosphine oxide, methyl 2,6 dimethoxybenzoyl-phenylphosphinate, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, methyl 2,4,6-trimethylbenzoylphenylphosphinate, 2,3,6-trimethylbenzoyldiphenylphosphine oxide, 2,3,5,6-tetramethylbenzoyl-diphenylphosphine oxide, 2,4,6-trimethoxybenzoyl-diphenylphosphine oxide, 2,4,6-trichlorobenzoyldiphenylphosphine oxide, 2-chloro-6-methyl-thio-benzoyl-diphenylphosphine oxide, methyl-2,4,6-trimethyl-benzoyl-naphthylphosphinate, 1,3-dimethoxynaphthalene-2-carbonyl-diphenylphosphine oxide and 2,8-dimethoxynaphthalene-1-carbonyl-diphenylphosphine oxide,

[0043] According to a particularly preferred embodiment, the photoinitiator P is ethyl(2,4,6-trimethylbenzoyl) phenylphosphinate (CAS No. 84434-11-7).

[0044] According to a preferred embodiment, it will be possible to associate with the photoinitiator P a polymeric co-initiator such as Genopol-AB-1 (from the company Rhan) which is a polymeric aminobenzoate derivative. The quantities will depend on the quantity of photoinitiator P used (photoinitiator P / co-initiator mass ratio between 5:1 and 1:5).

[0045] It is understood that in the formulas (I) And (II) described above for functionalized organosiloxane or organopolysiloxane A,if several radicals R are present, they can be the same or different from each other. Moreover, in the formulas (I) And (II), the symbol R can advantageously represent a monovalent radical chosen from the group consisting of: methyl, ethyl, propyl, 3,3,3-trifluoropropyl, xylyl, tolyl and phenyl.

[0046] Organopolysiloxane A can have a linear, branched, cyclic or network structure. When it comes to linear organopolysiloxanes, these can essentially consist of: of siloxyl units “D” chosen from the units of formulas R 2 SiO 2 / 2 , RZSiO 2 / 2 and Z 2 SiO 2 / 2 ; of siloxyl units “M” chosen from the units of formulas R 3 SiO 1 / 2 , R 2 ZSiO 1 / 2, RZ 2 SiO 1 / 2 and Z 3 SiO 1 / 2 , and the symbols R and Z are as defined above.

[0047] Examples of non-functionalized “D” units include dimethylsiloxy or methylphenylsiloxy siloxyl units and examples of non-functionalized “M” units include trimethylsiloxy and dimethylphenylsiloxy siloxyl units.

[0048] To continue the non-limiting definition of functionalized organosiloxane or organopolysiloxane A, it is specified that for the symbol Z of the examples of Y' alkenylcarbonyloxy radicals, we can cite acryloxy [CH 2 =CH-CO-O-] and the methacryloxy radicals: [(CH 3 )CH=CH-CO-O- ] and [CH 2 =C(CH 3 )-CO-O- ].

[0049] As an illustration of the symbol y, we will mention the radicals: CH 2 - ; (CH 2 ) 2 - ; (CH 2 ) 3 - ; CH 2 -CH(CH 3 )-CH 2 -; (CH 2 ) 3 -NH-CH 2 -CH 2 -; (CH 2 ) 3 -OCH 2 - ; (CH 2 ) 3 -[O-CH 2 -CH(CH 3 )-] -; (CH 2 ) 3 -O-CH 2- CH(OH)( -CH 2 -); (CH 2 ) 3 -O-CH 2 -C(CH 2 -CH 3 ) [-(CH 2 ) 2 -] 2 ;and (CH 2 ) 2 -C 6 H 9 (OH) -

[0050] Preferably, the functionalized organosiloxane or organopolysiloxane A has the formula ( IV ) next: formula in which: the symbols R 1< , which may be identical or different, each represent a linear or branched C 1 to C 18 alkyl group, a C 6 to C 12 aryl or aralkyl group, optionally substituted, preferably by halogen atoms, or an alkoxy radical -OR 4< with R 4< being a hydrogen atom or a hydrocarbon radical comprising from 1 to 10 carbon atoms, the symbols R 2< and R 3< , which may be identical or different, each represent either a radical R 1< or a monovalent radical of formula Z = -y-(Y')n in which: y represents a polyvalent linear or branched C 1 -C 18 alkylene radical optionally extended by bivalent oxyalkylene or polyoxyalkylene radicals C 1 to C 4 optionally substituted by a hydroxyl radical, Y' represents a monovalent alkenylcarbonyloxy radical, and n is equal to 1, 2 or 3, and with a = 0 to 1000, b = 0 to 500, c = 0 to 500, d = 0 to 500 and a+b+c+d= 0 to 2500,and the condition that at least one symbol R 2< or R 3< represents the monovalent radical of formula Z. ,

[0051] According to a preferred embodiment, in the formula (IV) above: - c=0, d=0, a= 1 to 1000, b= 1 to 250, the symbol R 2< represents the monovalent radical of formula Z and the symbols R 1< and R 3< have the same meaning as above.

[0052] Even more preferably, in the formula (IV) above: - c=0, d=0, a= 1 to 500, b= 1 to 100, the symbol R 2< represents the monovalent radical of formula Z and the symbols R 1< and R 3< have the same meaning as above.

[0053] These functionalized organopolysiloxanes A, in particular when they are linear, may be oils having a dynamic viscosity at 25°C of between 1 mPa.s and 100,000 mPa.s, preferably between 5 mPa.s and 10,000 mPa.s and even more preferably between 10 mPa.s and 5000 mPa.s.

[0054] According to a particularly preferred embodiment, the functionalized organopolysiloxane A is preferably chosen so that the curable silicone composition C advantageously has a viscosity not exceeding 5000 mPa.s, preferably not exceeding 4000 mPa.s at 25°C. As a variant, compositions with a viscosity of between 200 and 1000 mPa.s at 25°C will be preferred.

[0055] All the viscosities discussed in this presentation correspond to a dynamic viscosity quantity at 25°C called "Newtonian", i.e. the dynamic viscosity which is measured, in a manner known per se, with a Brookfield viscometer at a shear rate gradient sufficiently low so that the measured viscosity is independent of the rate gradient.

[0056] The synthesis of functionalized organosiloxane or organopolysiloxane Ais described in numerous patents. We can cite for example patents FR2362960, EP940422B1, EP979851B1, EP1276825B1, US3782940 and EP1544232B1.

[0057] As an adhesive and in particular as a pressure-sensitive adhesive PSAAny pressure-sensitive adhesive useful in accordance with the invention may be used. A description of pressure-sensitive adhesives suitable for use may be found in Encyclopedia of Polymer Science and Engineering, Vol. 13, Wiley-Interscience Publishers (New York, 1988). A further description of pressure-sensitive adhesives suitable for use may be found in Encyclopedia of Polymer Science and Technology, Vol. 1, Interscience Publishers (New York, 1964). Generally, the PSAs used herein may be any of the PSAs described in the aforementioned references. In one embodiment of the invention, the PSAs include natural or synthetic elastomers or acrylic-based adhesives. Examples are described in U.S. Pat. No. 5,164,444, U.S. Pat. No. 5,623,011, and U.S. Pat. No. 6,306,982. The adhesive may also be rubber-based, such as those described in the U.S No. 5,705,551 and in particular natural rubber. It may also be a radiation-curable mixture of monomers with initiators and other ingredients, such as those described in U.S. Pat. No. 5,232,958 and U.S. Pat. No. 5,232,958. The pressure-sensitive adhesives useful according to the invention are preferably emulsion and hot-melt. Conventional pressure-sensitive adhesives may be used, including silicone-based pressure-sensitive adhesives, rubber-based pressure-sensitive adhesives and acrylic-based pressure-sensitive adhesives.

[0058] Preferably, the pressure-sensitive adhesive is an acrylic adhesive in aqueous emulsion which is composed of acrylic homopolymers or copolymers in aqueous emulsion. It most often contains between 40 and 60% dry matter. It has viscosities between 0.3 and 0.6 Pa.s. It has the advantage of not containing organic solvents (non-flammable and no evaporation of harmful solvent).

[0059] Acrylic-based pressure-sensitive adhesives are particularly suitable in terms of cost, durability, pressure-sensitive adhesion characteristics, etc. As acrylic pressure-sensitive adhesives, mention may be made of those which comprise as a base polymer a copolymer or (meth)acrylic acid alkyl ester copolymer which contains an alkyl group having 4 to 12 carbon atoms as a main component. Examples of (meth)acrylic acid alkyl ester are butyl (meth)acrylate, isobutyl (meth)acrylate, hexyl (meth)acrylate, 2-hexyl (meth)acrylate, isononyl (meth)acrylate and isodecyl (meth)acrylate.In addition to the above main component, the base polymer can be polymerized with monomer components, for example, (meth)acrylic acid alkyl esters that contain an alkyl group that has 1 to 3 carbon atoms, acrylic acid, methacrylic acid, vinyl acetate, acrylonitrile, methacrylonitrile, and styrene, as required. In addition, other pressure-sensitive adhesives can be formulated with various additives. For acrylic-based pressure-sensitive adhesives, resins that impart tactile tack, for example, petroleum resins, terpene resins, rosin resins, coumarone-indene resins, and phenolic resins, as well as crosslinking agents such as isocyanate-based crosslinking agents and epoxy-based crosslinking agents, can be added. In addition, various additives, such as stabilizing agents and fillers, can be advantageously added.They are colorless and stable during storage and aging (low sensitivity to UV rays, and low sedimentation). Their slightly polar nature allows good wetting of the surfaces to be bonded and they have good adhesion performance. This type of adhesive is formulated by emulsion polymerization where one or more acrylic monomers, a reaction initiator and a surfactant are mixed in an aqueous medium to stabilize the micelles of the emulsion. As reaction initiator, two types are widely used: thermal (potassium or ammonium peroxodisulfate) or redox (bisulfate). The final water content of the emulsion varies between 40 and 60%. When applied in the form of an aqueous emulsion, the adhesive is therefore dried to form an adhesive layer.

[0060] Fillers can also be added to adhesives to increase the adhesive's volume and / or to improve properties. Fillers are commonly used in adhesive formulations for the following main reasons: (1) to reduce cost, for example by adding calcium carbonate, clay or talc; (2) to color adhesives, for example by adding titanium dioxide, color toner and security markers; and (3) to increase performance, for example by increasing stiffness and tensile strength, reducing cold flow, reducing lateral flow, improved die cutting, etc.

[0061] We distinguish between non-reinforcing inert fillers and reinforcing active fillers: Non-reinforcing inert fillers are fillers that do not react with the adhesive, such as untreated clay, talc, calcium carbonate, and titanium dioxide. They are added to the adhesive to increase the adhesive's volume, reduce cost, or change the adhesive's appearance or chemical resistance. Reinforcing active fillers are those that react with the adhesive, for example, by promoting additional crosslinking or filler-polymer interfacial interaction. Examples of such fillers include surface-treated clay, zinc oxide, fine-particle silica, and carbon black. This allows for an increase in mechanical properties, such as tensile strength or modulus, and, where applicable, adhesive properties.

[0062] In tape applications, the adhesive layer can be between a few hundred micrometers and a few thousand micrometers thick.

[0063] In label applications (usually the adhesive layer thickness is less than 100 micrometers), however, large amounts of fillers cause a significant loss of tack. Therefore, the amount of filler used for this application is more limited and will be chosen judiciously to avoid this problem.

[0064] As an example of back support DO papers, synthetic resin films, for example polyethylene, polypropylene and polyethylene terephthalate, rubber sheets, fabrics, non-woven fabrics, meshes, expanded sheets, metal films and their laminates can be used.

[0065] According to a preferred embodiment, the back support DO is chosen from the group consisting of: polymer films and papers.

[0066] As examples of back supports DO Paper materials useful in accordance with the invention include calendered papers, kaolin coated papers, and polyethylene coated papers. In particular, similar cellulosic materials prepared by processes such as soda, sulfite, or sulfate (kraft) processes, the neutral sulfide cooking process, alkali-chlorine processes, nitric acid processes, semichemical processes, and the like may also be used. Examples of papers that may be used as substrates for preparing the composite laminates of the present invention include kraft papers such as 40-pound and 50-pound bleached kraft papers, 41-pound offset-grade bleached kraft paper, and the like.

[0067] As other examples of back supports DO,we can cite those in polymer film for example in: vinyl polymer, poly(vinyl chloride), polyester (for example polyethylene terephthalate) and polyolefin (polyethylene such as LDPE, and polypropylene including biaxially oriented polypropylene), but also non-woven fabrics in polyester or cellulose fibers and polyurethane or polyethylene foams.

[0068] According to a particular embodiment, the back support DO is chosen from the group consisting of polyester films and kraft papers. Examples of kraft paper include supercalendered kraft paper or glassine paper, which is also a kraft paper but more dense.

[0069] Examples of front supports FRare, for example, cellulose derivatives such as labels, metal foils, polycarbonates or films made of: vinyl polymer, poly(vinyl chloride), polyester (e.g. polyethylene terephthalate) and polyolefin (polyethylene and polypropylene including biaxially oriented polypropylene).

[0070] According to a particular embodiment, the front support FR is selected from the group consisting of: cellulose derivatives, such as labels, metal foils, polycarbonates, polyethylene films, polyethylene terephthalate films, polypropylene films and vinyl films.

[0071] According to a preferred embodiment, the self-adhesive multi-layer article is characterized in that it is a self-adhesive label or a self-adhesive tape.

[0072] Another subject of the invention relates to the curable silicone composition Cas defined above.

[0073] In particular, the invention also relates to a curable silicone composition C by irradiation, not containing solvent and comprising as constituents: (a) at least one functionalized organosiloxane or organopolysiloxane A comprising: a1) at least one formula unit (I) next: R a Z b SiO (4-ab) / 2 (I)formula in which: the symbols R, identical or different, each represent a linear or branched C 1 to C 18 alkyl group, a C 6 to C 12 aryl or aralkyl group, optionally substituted, preferably by halogen atoms, or an alkoxy radical -OR 4< with R 4< being a hydrogen atom or a hydrocarbon radical comprising from 1 to 10 carbon atoms, the symbols Z are monovalent radicals of formula -y-(Y') n in which: y represents a polyvalent linear or branched C 1 -C 18 alkylene radical optionally extended by bivalent C 1 to C 4 oxyalkylene or polyoxyalkylene radicals optionally substituted by a hydroxy radical, Y' represents a monovalent alkenylcarbonyloxy radical, and n is equal to 1, 2 or 3, and a is an integer equal to 0, 1 or 2, b is an integer equal to 1 or 2 and the sum a+b= 1, 2 or 3; and a2) possibly patterns of formula (II) next: R a SiO (4-a) / 2 (II)formula in which: the symbols R, identical or different, each represent a linear or branched C 1 to C 18 alkyl group, a C 6 to C 12 aryl or aralkyl group, optionally substituted, preferably by halogen atoms, and a is an integer equal to 0, 1, 2 or 3, and b) an effective amount of at least one photoinitiator P type I of the family of acylphosphine oxide derivatives of formula (III) next: formula in which: the symbol R 5< is a monovalent radical -OR 8< with the symbol R 8< which is a hydrocarbon radical comprising from 1 to 8 carbon atoms; the symbol R 6< is a phenyl radical optionally substituted by: one or more halogen atom(s), a hydrocarbon radical comprising from 1 to 8 carbon atoms, a hydrocarbon alkoxy radical comprising from 1 to 8 carbon atoms, and / or a hydrocarbon thio radical comprising from 1 to 8 carbon atoms; and the symbol R 7< represents a hydrocarbon radical comprising from 1 to 12 carbon atoms, a benzyl radical or a phenyl radical optionally substituted by one or more halogen atom(s), a hydrocarbon radical comprising from 1 to 8 carbon atoms, a hydrocarbon alkoxy radical comprising from 1 to 8 carbon atoms and / or a cycloalkyl radical.

[0074] As stated above, the photoinitiator P preferred is ethyl (2,4,6-trimethylbenzoyl) phenylphosphinate.

[0075] Curable silicone compositions C by irradiation implemented according to the invention may also comprise other ingredients such as adhesion modulators making it possible to increase or decrease the adhesion forces obtained from the polyorganosiloxane alone, pigments, photosensitizers, fungicidal, bactericidal and antimicrobial agents, corrosion inhibitors, etc.

[0076] Another subject of the invention relates to a process for preparing a self-adhesive multilayer article according to the invention and as defined above comprising the following steps a) to d): a) a composition C according to the invention and as defined above is prepared by mixing its constituents; b) between 0.1 and 5 g per m 2 of the composition C obtained in the previous step is applied to the top face SI1 of a back support DOin order to obtain back support DO coated with the composition C, c) then the back support DO coated with the composition C is subjected to ultraviolet radiation in order to harden the composition by polymerization and / or crosslinking C to obtain a layer of non-stick silicone coating RC, and d) a step d1) or d2) is carried out: d1) at least one pressure-sensitive adhesive PSA, is applied to the non-stick silicone coating layer RC, then a front support FR is applied to the adhesive PSA, d2) an adhesive construction AD is prepared by applying on a front support FR at least one pressure-sensitive adhesive PSA, then the adhesive construction AD is attached with the back support DO coated with the composition C prepared in step c) so that the adhesive PSAis located between the back support DO and the front support FR, and e) possibly the composition C obtained in step a) is also applied to the underside SI2 back support DO then is subjected to ultraviolet radiation in order to harden the composition by polymerization and / or crosslinking C to obtain a layer of non-stick silicone coating RC on the underside SI2 back support DO, and then at least one pressure-sensitive adhesive PSA, is applied to this same layer of non-stick silicone coating RC.

[0077] According to an advantageous variant of the invention, the method according to the invention is characterized in that in step d) and / or e) a pressure-sensitive adhesive PSA, is applied in the form of an aqueous emulsion and then dried.

[0078] The quantities of the composition C according to the invention deposited on the supports are variable and are most often between 0.1 and 5 g per m 2< of treated surface. These quantities depend on the nature of the supports and the non-stick properties sought. They are more often between 0.3 and 1.5 g / m 2< for non-porous supports.

[0079] Preferably during step a) of the process according to the invention, the effective amount of photoinitiator P is between 0.1% and 5% by weight relative to the weight of the functionalized organosiloxane or organopolysiloxane A, and preferably between 0.1 and 3% by weight relative to the weight of the functionalized organosiloxane or organopolysiloxane A.

[0080] The UV radiation used has a wavelength between 100 and 400 nanometers. The irradiation time can be short and is generally less than 1 second and is of the order of a few hundredths of a second for very small thicknesses of compositions deposited on the surfaces. Crosslinking is advantageously carried out in the absence of any heating. However, heating between 25 and 100°C is not excluded from the invention.

[0081] In addition, the curing time can be adjusted, among other things, by the number of UV lamps used, the duration of UV exposure and the distance between the composition and the UV lamp.

[0082] According to an advantageous embodiment, UV LED lamps are used (UV emissions at 365, 375, 385 and / or 395 nm).

[0083] Crosslinking can be carried out, which results in hardening of the curable silicone composition C,continuously by passing the substrate coated with the composition through irradiation equipment which is designed to provide the coated substrate with sufficient residence time to complete curing of the coating. Curing should generally be carried out in the presence of the lowest possible oxygen concentration, typically at an oxygen concentration of less than 100 ppm, and preferably less than 50 ppm. Curing is generally carried out in an inert atmosphere, for example nitrogen or argon. The exposure time required to cure the curable silicone composition C varies with factors such as: the particular formulation used, the type and wavelength of radiation, the dose rate, the radiant flux, the photoinitiator concentration, and the atmosphere and coating thickness.

[0084] For curing by ultraviolet rays, a dose of ultraviolet rays in the range of about 0.1 to about 0.5 joules is generally sufficient. The exposure time is generally very short and curing is carried out in a time of about 0.1 to about 3 seconds. The actual exposure time required to achieve proper curing can be readily determined by those skilled in the art.

[0085] The compositions are applied using devices capable of depositing small quantities of liquids in a uniform manner. For this purpose, for example, the device called "Helio sliding" can be used, comprising in particular two superimposed cylinders; the role of the lowest cylinder, immersed in the coating tank where the composition is located, is to impregnate the highest cylinder in a very thin layer, the role of the latter is then to deposit on the support the desired quantities of composition with which it is impregnated; such a dosage is obtained by adjusting the respective speed of the two cylinders which rotate in opposite directions to each other. Any other technique known to those skilled in the art can also be used, such as: curtain coating, brush coating, spraying, coating by reverse rollers, doctor blade coating, etc.

[0086] According to a preferred embodiment, the method according to the invention is characterized in that in step c) the ultraviolet radiation has a wavelength between 100 and 400 nanometers inclusive.

[0087] Another subject of the invention relates to a substrate at least partially coated with a non-stick coating prepared by applying the curable silicone composition C according to the invention and as defined above and irradiation with ultraviolet radiation so as to cause its crosslinking.

[0088] Another subject of the invention relates to the use of a substrate at least partially coated with a non-stick coating according to the invention and as defined above in the field of self-adhesive labels, strips including envelopes, graphic arts, medical care and hygiene and construction and insulation.

[0089] Finally, the last object of the invention concerns the use of a self-adhesive multilayer article according to the invention and as defined above or of the curable silicone composition C by irradiation according to the invention and as defined above in the field of self-adhesive labels, strips including envelopes, graphic arts, medical care and hygiene and construction and insulation.

[0090] According to a variant of the invention, when the term "comprising" is used to describe the self-adhesive multilayer articles, the methods and the silicone compositions according to the invention, it can be replaced by the term "consisting of" without distorting the meaning of the invention.

[0091] The following examples and tests are given for illustrative and non-limiting purposes. They allow in particular to better understand the invention and to highlight all its advantages and glimpse some variant embodiments. EXAMPLE

[0092] The compositions are prepared by mixing one or more silicone oils A following the formula (IV) described above and a photoinitiator P whose structures are detailed below. Table 1: Structures of acryloxy-functionalized organopolysiloxanes Compound A R 1< R 2< R 3< a b d c A1 CH 3 CH 3 85 7 0 0 A2 CH 3 CH 3 220 4 0 0 A3 CH 3 CH 3 16 5 0 0 A4 CH 3 90 4 0 0 A5 CH 3 Not present in the formula 80 0 0 0 Table 2: Photoinitiators Photoinitiators Structures P1 = Irgacure ®< 1173 from BASF P2 = Tego ®< A18 from Evonik P3 = (ethyl(2,4,6-trimethylbenzoyl) phenylphosphinate) CAS No. 84434-11-7 Coating process

[0093] Silicone compositions are coated using a Rotomec coating pilot on different supports (Polyester or polypropylene). The machine speed is 50 or 100 m / min with a mercury lamp power set at 100W / cm to carry out crosslinking under UV. This deposition is controlled by XRF measurement. At the machine exit, the tests carried out are "smear", "rub-off", "dewetting" and the measurement of silicone extractables.

[0094] Tests carried out on supports coated with non-stick silicone coatings: Deposit : Control of the silicone deposit coated on the surface by X-ray fluorescence analysis of silicon (Oxford Lab-X 3000). An X-ray tube excites the electron shell of the silicon atoms, which causes an emission of X-rays proportional to the amount of excited silicon. This value or number of counts is converted by calculation (using the calibration line) into the amount of silicone. Smear : Qualitative control of surface polymerization by the finger trace method which consists of: Arranging the silicone-coated support sample to be checked on a flat and rigid surface; Making a trace with the tip of the finger by pressing moderately but clearly; and Examining the trace thus made visually, preferably in raking light. The presence of even a very slight trace can thus be seen by the difference in surface gloss.

[0095] The assessment is qualitative. We quantify the “Smear” with the following notations: A: very good, no fingerprints B: a little less good, barely visible marks C: clear marks D: very clear marks and oily surface appearance, product barely polymerized. or a grade from A to D, from best to worst result.

[0096] Rub-off : Checking the silicone's ability to adhere to the flexible support by rubbing it back and forth with the finger, which consists of: Place the silicone-coated support sample to be tested on a flat, rigid surface, with the silicone on the upper side. Move your fingertip back and forth 10 times (over a length of approximately 10 cm), pressing moderately but firmly. Visually examine the appearance of the peeling. Peeling corresponds to the appearance of a fine white powder or small balls that roll under the finger.

[0097] The assessment is qualitative. The scrubbing is quantified with the following notations: 10: very good, no appearance of scrubbing after 10 AR 1: very bad, scrubbing from the first trip

[0098] The score corresponds to the number of round trips (from 1 to 10) from which an eraser appears.

[0099] Either a score from 1 to 10, from lowest to best result.

[0100] Dewetting : Assessment of the degree of polymerization of the silicone layer by evaluating the transfer of silicone onto an adhesive placed in contact with the coating using a standardized surface tension ink. The method is as follows: Select a sample of approximately 20 x 5 cm of the silicone-coated paper to be characterized, taken in the unwinding direction (machine direction). Cut a length of approximately 15 cm of adhesive tape, then place it adhesive side down on the paper to be tested, without creases, applying pressure 10 times by sliding your finger along the length of the adhesive tape. (3M “Scotch” adhesive tape, reference 610, width: 25 mm). Remove the adhesive tape and place it flat, adhesive side upwards. Place a trace of ink over a length of approximately 10 cm on the adhesive side of the tape with a cotton swab (disposable). (SHERMAN or FERARINI and BENELI brand inks with a surface tension of approximately 30 dynes / cm and a viscosity of 2 to 4 mPa / s). Immediately start the stopwatch. We consider that we are entering the dewetting phase when the ink line changes appearance, then stop the stopwatch.The ink must be applied to the adhesive part of the tape within 2 minutes of silicone coating. If the result obtained is < 10 seconds, it is considered that there is migration of silicone onto the adhesive, and that polymerization is not complete. A score of 0 to 10 will be given, corresponding to the time elapsed in seconds before the dewetting phenomenon is observed. If the result obtained is 10 seconds, it is considered that polymerization is complete. In this case, a score of 10 will be given, meaning that the result is very good. Note the score obtained and the ink used (name, brand, surface tension, viscosity).

[0101] Extractables : Measurement of the amount of silicone that is not grafted to the network formed during polymerization. These silicones are extracted from the film by immersing the sample immediately after the machine exits in the MIBK for at least 24 hours. This is measured by flame absorption spectroscopy. Preparation of self-adhesive multi-layer articles

[0102] Adhesive supports conforming to TESA7475 (support = PET - adhesive = acrylic) and TESA4651 (support = acrylic coated fabric - adhesive = natural rubber) are complexed onto the silicone liner produced above (=support coated with a silicone coating obtained by crosslinking under UV) in order to form a multi-layer article. Tensile tests are carried out in order to determine the peel forces before and after aging as well as the subsequent adhesion and loop-tack values. These tests are described below. Test carried out on the obtained multi-layer articles

[0103] Subsequent adhesion or “Subsequent adhesion” (“SubAd” in the tables): Verification measurement of the retention of adhesiveness of adhesives (TESA 7475) having been in contact with the silicone coating according to the FINAT 11 (FTM 11) test known to those skilled in the art. Here the reference test piece is PET and the adhesives remained in contact with the silicone surface to be tested for 1 day at 70°C and 7 days at 70°C.

[0104] The results are expressed in % of retention of adhesive force of the reference tape: CA = (Fm2 / Fm1) x 100 in % with: Fm2 = Average tape peeling force after 20 h contact with silicone support; and Fm1 = Average tape peeling force without contact with silicone support.

[0105] Loop-tack : The loop-tack test consists of determining the force required to separate, at 300 mm / min, a loop of adhesive (TESA 7475) placed in contact and without pressure with a standard material. The result ratio between a clean adhesive and an adhesive complexed for 1 day at 23°C makes it possible to assess the loss of adhesiveness according to the FINAT 9 (FTM9) test known to those skilled in the art.

[0106] The final result will be the average of the three measurements expressed in N / Inch (unit: 1 inch = 2.54 cm).

[0107] Release: Peel force measurements were carried out with the standardized adhesives TESA 4651 and TESA 7475. The test pieces of the multi-layer article (adhesive in contact with silicone surface) were stored for 1 day at 23°C, 1 day at 70°C and 7 days at 70°C under the required pressure conditions, then tested at low peel speed according to the FINAT 3 (FTM 3) test known to those skilled in the art.

[0108] The peel force is expressed in cN / inch and is measured using a dynamometer, after pressurizing the samples either at room temperature (23°C) or at a higher temperature for accelerated aging tests (generally 70°C).

[0109] The results are recorded in Table 3 below. Table 3: Results of the evaluation of multi-layer articles. Coatings obtained from silicone oil with pendant acrylate functions. Article Comparative example 1 Comparative example 2 Example 1 (invention) Composition A1 100 100 100 P1 1 P2 1 P3 1 Support Polyester Lumirror Film Speed ​​100m / min 100W / cm lamp Deposit (g / m 2< ) 1,07 1,09 1,05 reaction by-product: benzaldehyde Yes No No reaction by-product: isopropanol Yes Yes No Characterization of the coating Smear A A A Rub-off 10 10 10 Dewetting 10 10 10 Extractable (100 cm 2< ) (%) 3,05 3,42 3,45 Characterization of the multilayer article SubAd 1d@70°C (TESA ref 7475) 1,0 1,0 1,0 SubAd 1d@70°C (%) 90 89 89 SubAd 7d@70°C (TESA ref 7475) 0,94 1,01 0,98 SubAd 7d@70°C (%) 94 100 97 Loop tack (N) according to FINAT3 (1d@23°C) 23,8 25,1 22,5 Loop tack (%) according to FINAT3 (1d@23°C) 111 117 105 Release Tesa 7475 1d @ 23°C 8,6 8,7 8,4 1d @ 70°C 11,73 10,37 10,23 7d @70°C 16,43 12,56 12,38 Release Tesa 4651 1d @ 23°C 26,9 28,1 25,9 1d @ 70°C 43,1 35,4 32,2 7d @70°C 70,1 70,3 71,7

[0110] Unlike comparative tests 1 and 2, example 1 according to the invention does not show any release of benzaldehyde or isopropanol during crosslinking under UV of the silicone composition coated on a polyester film, the crosslinking of the coating is optimal and the peel strengths of the adhesive of the multilayer article are satisfactory even after aging. Table 4. Coatings obtained from a silicone oil with pendant acrylate functions or a mixture of 2 silicone oils with pendant acrylate functions - variable levels of photoinitiators. Article Examples according to the invention Composition Ex.3 Ex.4 Ex.5 Ex.6 Ex.7 Ex.9 Ex.10 Ex.11 Ex.12 Ex.13 A1 100 100 99 99 97,5 97,5 97,5 95 95 95 A2 - - 1 1 2,5 2,5 2,5 5 5 5 P3 2 4 2 4 1 2 4 1 2 4 Support OPP CR30 Film (Innovia) Speed ​​50m / min 100W / cm lamp Deposit (g / m 2< ) 1,01 0,94 0,97 0,86 0,93 1,09 0,91 0,90 0,85 0,89 Characterization of the RC coating Smear A A A A A A A A A A Rub-off @ 0d 10 10 10 10 10 10 10 10 10 10 Rub-off @ 7d 10 10 10 10 10 10 10 10 10 10 Extractions (%) 3,8 3,8 3,7 5,1 5,4 5,2 5,0 4,2 4,7 4,8 Characterization of the multilayer article Subadhesion 1d@23° (ref Tesa7475) 0,95 0,94 0,88 0,97 0,93 0,94 0,98 0,92 0,9 0,9 Subadhesion 1d@23°C (%) 99,0 97,9 91,7 101,0 96,9 97,9 102,1 95,8 93,8 93,8 Release TESA7475 1d @ 23°C 3,8 4,7 3,6 4,5 2,9 3,6 4,7 2,9 3,5 5,3 1d @ 70°C 5,3 7,4 5,3 7,5 4,0 5,1 7,6 4,0 5,6 8,8 7d @70°C 7,5 27,8 7,7 9,3 5,9 7,0 9,9 6,0 8,3 11,6 Release TESA4651 1d @ 23°C 10,1 13,4 8,3 11,5 6,1 7,4 12,2 5,6 7,4 12,9 1d @ 70°C 17,8 26,9 13,4 23,2 9,3 12,7 23,8 9,3 13,7 28,2 7d @70°C 22,2 39,3 17,8 29,1 14,5 15,7 31,0 14,0 17,4 36,4

[0111] All the examples according to the invention do not show any release of benzaldehyde and / or isopropanol during the crosslinking under UV of the silicone compositions based on an oil with acrylate functions according to the invention or the mixture of two oils with acrylate functions according to the invention coated on a polypropylene film. In addition, the crosslinking of the coatings is optimal and the peel forces of the adhesive of the multilayer articles are correct, regardless of the concentration of photoinitiator. Table 5. Coatings obtained from a mixture of two silicone oils with acrylate functions, respectively pendant and chain ends: Article Comparative example 3 Example 14 Composition A3 30 30 A5 70 70 P2 2 P3 2 Support PET Lumirror Film Speed ​​50m / min 100W / cm lamp Deposit (g / m 2< ) 0,75 0,73 reaction by-product: benzaldehyde No No reaction by-product: isopropanol Yes No Characterization of the RC coating Smear B A Rub-off 2 10 Dewetting 0 10 Extractable (100 cm 2< ) (%) 17,4 7,3 Characterization of the multilayer article SubAd 1d@70°C (TESA ref 7475) ND 0,9 SubAd 1d@70°C (%) ND 84,9 SubAd 7d@70°C (TESA ref 7475) ND 0,92 SubAd 7d@70°C (%) ND 85,44 Loop tack (N) according to FINAT3 (1d@23°C) ND 20,8 Loop tack (%) according to FINAT3 (1d@23°C) ND 75,9 Release Tesa 7475 1d @ 23°C ND 6,52 1d @ 70°C ND 7,9 7d @70°C ND 20,2 Release Tesa 4651 1d @ 23°C ND 13,69 1d @ 70°C ND 11,5 7d @70°C ND 11,94 ND = not determined because of high extractable rate

[0112] Unlike comparative example 3, example 14 according to the invention does not show any release of benzaldehyde or isopropanol during crosslinking under UV of the silicone composition based on two silicone oils with acrylate functions according to the invention coated on a polyester film. In addition, the crosslinking of the coating and the peel forces of the adhesive of the multilayer article are correct.

[0113] The photoinitiator used in comparative example 3 does not allow satisfactory crosslinking of the composition based on two silicone oils with acrylate functions, respectively pendant and chain ends (extractable content of 17.4%). Table 6. Coatings obtained from a mixture of a silicone oil with pendant acrylate functions and a silicone oil with chain end and pendant acrylate functions. Article Example 15 Invention Composition A3 30 A4 70 P3 2 Support PET Lumirror Film Speed ​​50m / min 100W / cm lamp Characterization of the RC coating Deposit (g / m 2< ) 0,74 Smear A Rub-off 10 Extractable (100 cm 2< ) dosage value 3,6 Extractable (100 cm 2< ) (%) 6,5 Characterization of the multilayer article Subadhesion 1d@70°c (ref Tesa 7475) 0,85 Subadhesion 1d@70°c (%) 79,73 Subadhesion 7d@70°c (ref Tesa 7475) 0,89 Subadhesion 7d@70°c (%) 82,91 Loop tack (N) according to FINAT3 (1d@23°C) 19,42 Loop tack (%) according to FINAT3 (1d@23°C) 70,90 Release TESA 7475 1d @ 23°C 7,685 1d @ 70°C 7,885 7d @70°C 16,365 Release TESA 4651 1d @ 23°C 10,155 1d @ 70°C 10,6 7d @70°C 36,18

[0114] Example 15 according to the invention does not show any release of benzaldehyde and / or isopropanol during crosslinking under UV of a composition comprising a mixture of a silicone oil with only pendant acrylate functions and a silicone oil with pendant acrylate functions and chain ends.

[0115] In addition, the crosslinking of the coating and the peel strengths of the adhesive of the multi-layer article are correct.

[0116] All of these examples clearly show that the use of a photoinitiator of the acylphosphine oxide type and more particularly ethyl(2,4,6-trimethylbenzoyl)-phenylphosphinate during the manufacture of a self-adhesive multilayer article makes it possible on the one hand to protect operators and the environment and on the other hand to lead to optimal properties whatever the silicone acrylate oils used in the silicone composition implemented, which is not the case for the photoinitiators most used industrially.

Claims

1. Self-adhesive multi-layer item comprising: 1) a dorsal support DO having a top face SI1 and a bottom face SI2, 2) at least one layer of silicone release coating RC applied on the top face SI1 of the dorsal support DO and which is prepared by irradiation of a curable silicone composition C not containing any solvent and comprising, as constituents: a) at least one functionalized organopolysiloxane A comprising: a1) at least one unit of formula (I) below:         RaZbSiO(4-a-b) / 2     (I) in which formula: - the symbols R, which may be identical or different, each represent a linear or branched C1 to C18 alkyl group, a C6 to C12 aryl or aralkyl group, which is optionally substituted, preferably with halogen atoms, or an alkoxy radical -OR4 with R4 being a hydrogen atom or a hydrocarbon-based radical comprising from 1 to 10 carbon atoms, - the symbols Z are monovalent radicals of formula - y-(Y')n in which: • y represents a linear or branched C1-C18 polyvalent alkylene radical optionally extended by C1 to C4 oxyalkylene or polyoxyalkylene divalent radicals, which is optionally substituted with a hydroxyl radical, • Y' represents an alkenylcarbonyloxy monovalent radical, and • n is equal to 1, 2 or 3, and - a is an integer equal to 0, 1 or 2, b is an integer equal to 1 or 2 and the sum a+b = 1, 2 or 3; and a2) optionally units of formula (II) below:         RaSiO(4-a) / 2     (II) in which formula: - the symbols R, which may be identical or different, each represent a linear or branched C1 to C18 alkyl group, a C6 to C12 aryl or aralkyl group, which is optionally substituted, preferably with halogen atoms, and - a is an integer equal to 0, 1, 2 or 3, and b) an effective amount of between 0.1% and 5% by weight relative to the weight of the functionalized organosiloxane or organopolysiloxane A of at least one type I photoinitiator P of the family of acylphosphine oxide derivatives of formula (III) below: in which formula: - the symbol R5 is a monovalent radical -O-R8 with the symbol R8 being a hydrocarbon-based radical comprising from 1 to 8 carbon atoms; - the symbol R6 is a phenyl radical optionally substituted with: - one or more halogen atom(s), - a hydrocarbon-based radical comprising from 1 to 8 carbon atoms, - a hydrocarbon-based alkoxy radical comprising from 1 to 8 carbon atoms, and / or - a hydrocarbon-based thio radical comprising from 1 to 8 carbon atoms; and - the symbol R7 represents a hydrocarbon-based radical comprising from 1 to 12 carbon atoms, a benzyl radical or a phenyl radical optionally substituted with one or more halogen atom(s), a hydrocarbon-based radical comprising from 1 to 8 carbon atoms, a hydrocarbon-based alkoxy radical comprising from 1 to 8 carbon atoms and / or a cycloalkyl radical; 3) at least one pressure-sensitive adhesive PSA, applied on the layer of silicone release coating, 4) a frontal support FR applied on the adhesive PSA of the component 3), and 5) optionally at least one layer of silicone release coating RC applied on the bottom face SI2 of the dorsal support DO and which is prepared by application and irradiation of said curable silicone composition C, and on this same layer there is at least one pressure-sensitive adhesive PSA.

2. Self-adhesive multi-layer item according to Claim 1, characterized in that the dorsal support DO is chosen from the group made up of: polymer films and papers.

3. Self-adhesive multi-layer item according to Claim 1, characterized in that the frontal support FR is chosen from the group made up of: cellulose-based derivatives, metal sheets, polycarbonates, polyethylene films, polyethylene terephthalate films, polypropylene films and vinyl films.

4. Self-adhesive multi-layer item according to Claim 1, characterized in that the effective amount of photoinitiator P is between 0.1% and 3% by weight relative to the weight of the functionalized organosiloxane or organopolysiloxane A.

5. Self-adhesive multi-layer item according to Claim 1 or 3, characterized in that the photoinitiator P is ethyl (2,4,6-trimethylbenzoyl)phenylphosphinate.

6. Self-adhesive multi-layer item according to any one of the preceding claims, characterized in that it is a self-adhesive label or a self-adhesive tape.

7. Process for preparing a self-adhesive multi-layer item as defined in any one of Claims 1 to 5, comprising the following steps a) to d): a) a composition C as defined in Claim 1 or 4 is prepared by mixing its constituents; b) between 0.1 and 5 g per m2 of the composition C obtained in the preceding step is applied on the top face SI1 of a dorsal support DO in order to obtain the dorsal support DO coated with the composition C, c) the dorsal support DO coated with the composition C is then subjected to ultraviolet radiation in order to cure, by polymerization and / or crosslinking, the composition C making it possible to obtain a layer of silicone release coating RC, and d) a step d1) or d2) is carried out: d1) at least one pressure-sensitive adhesive PSA is applied on the layer of silicone release coating RC, and then a frontal support FR is applied on the adhesive PSA, d2) an adhesive construction AD is prepared by applying, on a frontal support FR, at least one pressure-sensitive adhesive PSA, and then the adhesive construction AD is joined with the dorsal support DO coated with the composition C prepared in step c) in such a way that the adhesive PSA is located between the dorsal support DO and the frontal support FR, and e) optionally, the composition C obtained in step a) is also applied on the bottom face SI2 of the dorsal support DO and is then subjected to ultraviolet radiation in order to cure, by polymerization and / or crosslinking, the composition C making it possible to obtain a layer of silicone release coating RC on the bottom face SI2 of the dorsal support DO, and subsequently at least one pressure-sensitive adhesive PSA is applied on this same layer of silicone release coating RC.

8. Process according to Claim 7, characterized in that, in step d) and / or e), a pressure-sensitive adhesive PSA is applied in the form of an aqueous emulsion and is then dried.

9. Process according to Claim 8, characterized in that, in step c), the ultraviolet radiation has a wavelength of between 100 and 400 nanometres, limits included.

10. Substrate at least partially coated with a release coating prepared by application of the curable silicone composition C as defined in any one of Claims 1 to 6 and irradiation by ultraviolet radiation so as to bring about the crosslinking thereof.

11. Use of a self-adhesive multi-layer item as defined in any one of Claims 1 to 6 in the field of self-adhesive labels, of bands including envelopes, of graphic arts, of medical and hygiene care and of construction and insulation.

12. Use of a substrate at least partially coated with a release coating as defined in Claim 10 in the field of self-adhesive labels, of bands including envelopes, of graphic arts, of medical and hygiene care and of construction and insulation.