FR2818169A1 - METHOD FOR FIGHTING FOG APPEARANCE DURING THE COATING OF FLEXIBLE CARRIERS WITH A CROSSLINKABLE LIQUID SILICONE COMPOSITION IN A CYLINDERS DEVICE - Google Patents

Abstract

The invention concerns a method for preventing misting when coating flexible supports with at least a liquid silicone (RTV polyaddition) composition precursor of silicone coating(s), with a coating device comprising rollers operating at high speed. The invention aims at increasing misting speed and consequently enhancing the appearance, the mechanical properties of the silicone coating, as well as industrial hygiene. Therefor, it consists in using a liquid coating composition obtained by mixing: a silicone phase comprising one or several POS (A) and optionally one or several (crosslinking) compound(s) (B) having a viscosity eta at 25 DEG C ranging between 100 and 800 mPa's; with 1 to 10 wt. % of an anti-misting aqueous silicone (water-in-oil) emulsion having an aqueous phase phi a comprising at least 20 wt. % of water; and optionally with a water/solvent liquid (D).

Description

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METHOD FOR CONTROLLING THE FOG APPEARANCE DURING THE COATING OF FLEXIBLE CARRIERS WITH A SILICONE COMPOSITION
CROSSLINKABLE LIQUID IN A CYLINDERS DEVICE
The invention relates to the general field of silicone coating on high speed cylinders of various flexible substrates, such as sheets of paper or of synthetic polymer (polyolefin, polyester, etc.), or else of textile.

 More specifically, the invention relates to the coating of flexible materials with liquid compositions containing one or more polyorganosiloxanes (POS) crosslinkable by polyaddition, by polycondensation (emulsion), cationically or radical, so as to form a film or protective coating having in particular antiblocking and / or hydrophobic properties.

 Flexible media can be paper, cardboard, plastic film, or metal film. The applications of these silicone-coated substrates are for example: food paper (baking molds, packaging), label / adhesive tape, seal, etc.

 The coating of these flexible supports with crosslinkable liquid silicones is carried out on coating devices operating continuously, and at a very high speed. These devices comprise coating heads consisting of several cylinders including a pressure roll and a coating roll, which is fed continuously in crosslinkable liquid silicone composition, by means of a series of rollers contiguous to each other. The flexible support strip travels at a high speed between the pressure roll and the coating roll to be coated on at least one of its faces with a silicone film intended to crosslink by means of crosslinking means arranged downstream of the roll head. coating. These crosslinking means may be emitters of heat, radiation (e.g., UV) or electron beams for example.

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In the race for productivity, manufacturers of flexible substrates coated with non-stick silicone are demanding silicone liquid coating formulations, adapted to linear speeds of scrolling the band of flexible media increasingly high. The economic factor is obviously not insignificant in this search for new silicone formulations for high-speed coating.

 However, it is known that the high speeds on continuous coating machines, are synonymous with problems of transfer of the silicone liquid film of the coating roll on the moving flexible support strip. These transfer problems ("splitting") result in particular by the appearance of a mist or an aerosol ("misting", "fogging") in the environment of the coating head and, more particularly, the level of the contacts between the rotating cylinders and / or between the coating roll and the flexible support to be coated. The density of this fog or aerosol increases as the linear speed of travel and thus the speed of rotation of the cylinders increases.

 This phenomenon results first of all in a loss of consumables, and especially a deposit of droplets of coating liquid on the support downstream (for example at the oven), which seriously affects the quality of the coating: aspect orange peel, lack of coverage, mechanical properties of the cross-linked coating (rub-off), anti-adhesion.

 In addition, this undesirable formation of fog has adverse consequences for the industrial hygiene and safety of operators, who are exposed to the vicinity of the roll coating device, a high aerosol content. This can be harmful.

 Moreover, the "misting" causes rapid fouling of the roll coating device, resulting in maintenance constraints and premature wear.

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To guard against the consequences of this fog, it is generally available around the coating head, a suction system for capturing said fog.

Moreover, the skilled person knows a number of settings of the coating head to counteract this phenomenon. Some examples are given below:
A. lowering speed to the detriment of productivity;
B. decrease the rate of silicone deposition to the detriment of the properties of the flexible silicone support that is to be obtained (appearance, coverage, anti-adhesion, mechanical properties);
C. increasing the difference between the tangential speed of the coating roll and the linear speed of the paper. But beyond a certain differential, the homogeneity of the coated layer is seriously disturbed. In addition, it reduces the density of the fog without annihilating enough to allow a significant increase in the coating speed;
D. increasing the pressure between the coating roll and the pressure roll; here again in a certain limit and without any interesting suppression of the phenomenon of fog formation.

 Another approach to combat the formation of fog in roll coating machines is to act on the formulation of the liquid silicone coating composition.

According to this approach, it is known to reduce the number-average degree of polymerization of the POS constituting the silicone coating liquid and, consequently, to reduce the viscosity of the silicone coating bath to limit the density of the mist.

These known methods suffer from a serious drawback which is to modify substantially the properties and, in particular, the anti-

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adhérence du support flexible siliconé que l'on cherche à obtenir.

adhesion of the silicone flexible support that is sought to obtain.

 As an illustration of this approach through the silicone formulation, mention may be made of the European patent application EP-0 716 115 which describes a process for manufacturing a silicone composition for high speed coating with rolls, this composition being presented as allowing the reduction of the fog density. According to this process, a trimethylsilyl-terminated polydimethylmethylhydrogenosiloxane with a degree of polymerization of 12 is used, as well as 0.01% of a polydimethylsiloxane substituted by perfluoroethylbutyl and methylvinyl functions, the ends of which are of the dimethylvinylsiloxyl type and of degree of polymerization equal to 300, as well as polypropylene glycol and optionally a stearic or oleic alcohol. This leads to polydimethylsiloxanes functionalized with polyoxypropylene groups. These functionalized PDMSs are associated with other functionalized PDMSs, e. g. by hexene units as well as a platinum-based hydrosilylation catalyst to form silicone coating compositions to reduce fog formation. The functionalization units may be hydrophobic residues such as residues of stearic or oleic acid.

It is clear that such compositions are relatively complex and therefore expensive to obtain. Moreover, they are still perfectible with regard to the fight against the formation of fog in silicone coating on rolls, at high speed.

 US Pat. No. 4,808,391 relates to inks and varnishes based on silicone, and more specifically to a process for applying these inks / varnishes to a substrate, using a roller coating machine operating at high speed. . This patent notably discloses compositions comprising

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polydiméthylsiloxanes PDMS à extrémités vinylées de viscosité à 25 C comprise entre 15000 et 50000 mPa. s. (Exemples XII et XIII : 30000 et 18000 mPa. s à 25 C respectivement). Ces compositions liquides d'enduction comprennent également un catalyseur à base de platine et un additif rhéologique constitué par de la silice à haute surface spécifique, en particulier de la silice de combustion, à raison de moins de 1% et de moins de 5% en poids sur sec, dans les exemples XII et XIII respectivement.

PDMS polydimethylsiloxanes having vinyl ends with a viscosity at 25 ° C. of between 15000 and 50000 mPa. s. (Examples XII and XIII: 30000 and 18000 mPa.s at 25 C respectively). These liquid coating compositions also comprise a platinum-based catalyst and a rheological additive consisting of silica with a high specific surface area, in particular combustion silica, in a proportion of less than 1% and less than 5% by weight. weight on dry, in examples XII and XIII respectively.

This composition also comprises a polymethylhydrogenosiloxane capable of reacting with POS Si-Vi in the presence of a platinum catalyst.

According to this patent, it is the choice of a precise interval of viscosity between 15000 and 50000 mPa. s for the Si-Vi majority POS, which provides a solution to the fogging problem. In fact, in this patent, only liquid coating compositions without a silica-type rheological additive were tested in a high-speed roller coating device. From the results obtained, the acceptable fog reduction / rheological behavior compromise is in the viscosity range between 10000 and 60000 mPa. s to 25OC.

This document does not teach anything about a possible positive effect of the rheological additive on the fight against fog formation.

 US Pat. No. 6,057,033 discloses silicone compositions intended to be coated on flexible substrates to form, after cationic cross-linking under UV, with a non-stick coating. In addition to POS, these compositions comprise cellulose fibers having an average length of between 15 and 100 g and an average thickness of between 5 and 40 um. The POSs implemented are POS functionalized by groups of

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réticulation du type acryloxy ou méthacryloxy, permettant la réticulation par voie radicalaire sous UV. Les fibres de cellulose incorporées dans la composition permettent d'apporter une solution au problème technique qui est d'obtenir un revêtement silicone anti-adhérent réticulé non cassant. Les fibres de cellulose sont présentées comme procurant des améliorations en ce qui concerne le transfert du film de silicone d'enduction sur le support, la résistance au découpage, les propriétés mécaniques (résistance à la tension et à la déchirure), la fixation du revêtement sur le papier, la diminution de l'absorption du liquide d'enduction au sein du papier, et accessoirement la réduction de la formation de brouillard.

crosslinking of the acryloxy or methacryloxy type, allowing radical crosslinking under UV. The cellulose fibers incorporated in the composition make it possible to provide a solution to the technical problem which is to obtain a non-brittle cross-linked non-stick silicone coating. The cellulose fibers are presented as providing improvements in the transfer of the silicone coating film to the substrate, the cutting resistance, the mechanical properties (tensile and tear resistance), the fastening of the coating on paper, the reduction of the absorption of the coating liquid within the paper, and incidentally the reduction of the formation of fog.

On this last point, US Pat. No. 6,057,033 does not provide any quantitative element for assessing the fog reduction caused by cellulosic fibers. There is every reason to believe that this reduction remains quite inadequate.

 Furthermore, it should be noted that the use of particulate fillers, for example siliceous, in liquid silicone compositions intended to be coated on flexible substrates, for example made of paper to form crosslinked non-adherent coatings, is a characteristic known since for a very long time, that is to say since the appearance of non-stick silicone coatings (see US Pat. No. 3,503,782).

 Japanese patent application JP-62 64 011, which describes a coating liquid containing a film-forming resin and a solvent and which also contains wax particles with a diameter of between 1 and 10 μm, the diameter of the particle, is also mentioned for the record. the largest being at most equal to 150% of the thickness of the wet coating film applied to the support. Such a coating liquid would allow an increase in the coating speed of at least 10 to 30

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m/min, a priori grâce à une limitation de la formation de brouillard. L'enseignement d'un tel document est à écarter car il ne concerne pas les revêtements silicone.

m / min, a priori thanks to a limitation of the formation of fog. The teaching of such a document is to be rejected because it does not concern silicone coatings.

 In such a state of the art, one of the essential objectives of the invention is to propose an effective method of combating the appearance of fog when coating flexible substrates with a liquid silicone precursor composition of crosslinked coatings, this coating is performed using a cylinder coating device operating at high speed.

 Another essential objective of the invention is to propose an economical and simple method of combating the appearance of fog when coating flexible substrates with a silicone composition intended to crosslink, this coating being carried out in a device for cylinder coating operating at high speed.

 Another essential object of the invention is to propose a method of coating flexible supports at high speed on a roller apparatus, in which the formation of fog is reduced, so that the speed of appearance of this disturbance is significantly increased.

 Another essential object of the invention is to provide a novel additive which makes it possible to reduce the formation of fog during high-speed coating on rolls, of flexible materials, by means of silicone compositions which can be crosslinked in non-stick coatings.

 Another essential objective of the invention is to propose a method for combating the appearance of fog in the context of the coating of flexible supports, with a silicone composition crosslinkable in anti-adherent coatings, using a cylinder coating device, said method having to have positive effects on appearance and / or coverage and / or mechanical properties (rub-off) and / or

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les propriétés d'anti-adhérence du revêtement réticulé que l'on cherche à obtenir sur au moins une des faces du support flexible.

the anti-adhesion properties of the crosslinked coating that is to be obtained on at least one of the faces of the flexible support.

- C- éventuellement au moins un catalyseur de la réaction de réticulation ; caractérisé en ce que l'on met en oeuvre une composition liquide d'enduction obtenue par mélange : * d'une phase silicone comportant un ou plusieurs POS (A) et éventuellement un ou plusieurs composés (s) (B) (réticulant) et dont la viscosité n à 25 C est inférieure à 2000 mPa. s, de préférence comprise entre 100 et 1400 mPa. s, et plus préférentiellement encore comprise entre 100 et 800 mPa. s ; avec une Emulsion Silicone Aqueuse Anti-Brouillard (ESAAB) dont la phase aqueuse (pa comprend au moins
20% poids d'eau, de préférence de 20 à 90% poids d'eau, et plus préférentiellement encore de 20 à 70% poids d'eau ; * et éventuellement avec un composé liquide (D) constitué par un diluant et/ou un solvant consistant dans un composé organique non organosilicique ou organosilicique, capable ou non de réagir avec le (ou les) composé (s) (A). All these objectives, among others, are achieved by the present invention which firstly relates to a method of combating the appearance of fog ("misting") during the coating of flexible supports with at least one silicone composition silicone coating precursor liquid, using a roll coating device, the liquid composition comprising: - A- at least one polyorganosiloxane (POS) crosslinkable by polyaddition, by polycondensation, cationically or by radical pathway - B- optionally at least one cross-linking organosilicon compound

- C- optionally at least one catalyst of the crosslinking reaction; characterized in that a liquid coating composition obtained by mixing: a silicone phase comprising one or more POS (A) and optionally one or more compounds (B) (crosslinking) and whose viscosity n at 25 C is less than 2000 mPa. s, preferably between 100 and 1400 mPa. s, and more preferably still between 100 and 800 mPa. s; with an Aqueous Silicone Emulsion Anti-Fog (ESAAB) whose aqueous phase (pa comprises at least
20% by weight of water, preferably from 20 to 90% by weight of water, and even more preferably from 20 to 70% by weight of water; and optionally with a liquid compound (D) consisting of a diluent and / or a solvent consisting of a nonorganosilicic or organosilicic organic compound, capable or not of reacting with the compound (s) (A).

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All the viscosities referred to herein correspond to a dynamic viscosity quantity at 25c, referred to as "Newtonian", that is to say measured, in a manner known per se, at a sufficiently high shear rate gradient. low so that the measured viscosity is independent of the velocity gradient.

 It is the merit of the inventors to have been able to understand the phenomenon that presides over the formation of mist during the transfer of the liquid silicone layer from the coating roll onto the strip of flexible supports to be coated. Thus, on the basis of the fact that the liquid silicone filaments which are created during the transfer must be broken as soon as possible after their formation, the inventors have proposed the use of an aqueous silicone emulsion capable of creating in situ (in the coating machine) conditions such that the silicone liquid filaments are broken early, during the transfer of the coating roll on the moving strip, without causing unacceptable disturbances on the viscosity of the liquid composition.

The result obtained by virtue of the invention is an effective control of the formation of fog, which results in a significant increase in the speed of appearance of said fog in a cylinder coating system operating at high speed.

- de la concentration en ESAAB dans la composition, - et de la proportion de pa dans l'ESAAB. The control of the amount of water present in the composition, is through:

- the concentration of ESAAB in the composition, - and the proportion of pa in the ESAAB.

 Without wishing to be bound by the theory, it is postulated that, in the context of the implementation of the method according to the invention, a transformation of the ESAAB and / or an evolution (presumably downwards) of the particle size of the dispersed phase of the liquid composition

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d'enduction. En effet, les opérations de mélange de l'émulsion ESAAB et de la phase silicone ainsi que les forts cisaillements subis par la composition liquide d'enduction dans la machine du même nom (en particulier dans les rouleaux de celle-ci), sont susceptibles de modifier l'émulsion.

coating. Indeed, the mixing operations of the ESAAB emulsion and of the silicone phase as well as the strong shearings experienced by the liquid coating composition in the machine of the same name (in particular in the rollers thereof), are susceptible to modify the emulsion.

le cas où l'ESAAB est une émulsion directe huile-dans-eau, il se forme in situ une émulsion multiple huile-dans-eau-danshuile. Thus, when ESAAB is a water-in-oil inverse emulsion, the grain size is likely to decrease. And in

In the case where ESAAB is a direct oil-in-water emulsion, a multiple oil-in-water-in-oil emulsion is formed in situ.

 Regarding the particle size distribution of the dispersed phase (ESAAB pd), it is chosen in such a way as to give the ESAAB some stability.This grain size is not critical.

Nevertheless, to fix the ideas one will specify that the dispersed phase (pd of the ESAAB is formed by droplets whose particle size, given by their Dso (in hum), is such that:
Dso 100, preferably 0.001 Dso 50 Within the meaning of the invention, the Dso parameter is the median size of the particle size distribution. It can be determined on the cumulative particle size distribution graph, obtained by one of the analytical techniques mentioned below, by determining the size corresponding to the cumulation of 50% of the particle population. Specifically, this grain size parameter Dso corresponds to the average maximum dimension of at least 50% of the mass of particles considered, a Dso of 10 Um indicates that 50% of the particles have a size less than 10 m. Granulometry measurements can be made by conventional techniques such as sedimentation, laser diffraction (eg COULTER @ LSI30), optical microscopy coupled with image analysis, etc.

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According to a preferred embodiment of the process according to the invention, the ESAAB is a reverse emulsion of the water-in-oil type.

This inverse ESAAB of the water-in-oil type is an emulsion: - whose dispersed phase (pd is formed by droplets of water optionally additive, the Dso of these droplets being as defined above, and whose phase continue (pc consists of at least one silicone oil and possibly at least one additive.

 According to a subsidiary mode of implementation of the invention, the ESAAB is a direct emulsion of the oil-water type. This direct ESAAB of the oil-in-water type is an emulsion: - whose dispersed phase (pd is formed by droplets of silicone oil of Dso as defined above, and whose continuous phase (aqueous pc is optionally additivated.

 These reverse or direct ESAABs are obtained by emulsification processes well known to those skilled in the art. These processes involve the mixing of an aqueous phase and an oily phase without and with grinding, that is to say under high shear.

In the art, inversion emulsification methods and direct emulsification methods are distinguished.

The inversion emulsification processes for obtaining, for example, oil-in-water emulsions involve the prior formation of a water-in-oil emulsion (commonly referred to as an inverse emulsion) and then the inversion of this emulsion, whereby gets an emulsion in the water.

Direct emulsification processes for obtaining oil-in-water or water-in-oil emulsions are processes in which the emulsion is all or long of its

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préparation et dès sa formation, une émulsion directe, c'est-àdire une émulsion huile-dans-eau ou inverse eau-dans-huile.

preparation and from its formation, a direct emulsion, that is to say an oil-in-water emulsion or reverse water-in-oil.

 The ESAAB emulsions are advantageously stabilized with one or more surfactants. These surfactants can be nonionic, anionic, cationic, or even zwitterionic. The surfactants are chosen more generally as a function of the HLB. The term Hydrophilic Lipophilic Balance (HLB) refers to the ratio of the hydrophilicity of the polar groups of the surfactant molecules to the hydrophobicity of their lipophilic moiety. HLB values are particularly reported in various basic manuals such as the "Handbook of Pharmaceutical Excipients, The Pharmaceutical Press, London, (1994)".

According to one variant, the stabilization of the silicone / water emulsions can be carried out using protective colloids such as polyvinyl alcohols.

The water / silicone emulsions can also be stabilized via silicone surfactant-surfactant silicone polyesters Science Series V86 Ed Randal M. Hill (1999)].

On the other hand, it should be noted that solid particles can allow the stabilization of oil-in-water or oil-in-oil emulsions.

Thus, according to an advantageous characteristic of the invention, it is proposed to use particles of silica-preferably hydrophilic-whose contact angle is close to 00, as a means of stabilizing the ESAAB (emulsion water-oil or oil-in-water), in combination with at least one suitable co-stabilizer. The role of the latter is to allow the modification of the contact angle.

In practice, the co-stabilizers may be nonionic, anionic, cationic or even zwitterionic surfactants.

In addition, it should be noted that specific treatments of the particulate hydrophilic silica make it possible to obtain varying degrees of hydrophobization and to optimize the contact angle.

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(Journal of colloid and interfaces science 213, 352-359 (1999)). A propos de l'angle de contact, il faut noter en effet, que la formation d'une émulsion huile-dans-eau est favorisée quand l'angle de contact entre l'huile, le solide et l'eau est inférieur à 900C. Quand l'angle de contact est supérieur à 900C, une émulsion eau-dans-huile peut être stabilisée.

(Journal of colloid and interfaces science 213, 352-359 (1999)). With regard to the contact angle, it should be noted that the formation of an oil-in-water emulsion is favored when the contact angle between the oil, the solid and the water is less than 900 ° C. . When the contact angle is greater than 900C, a water-in-oil emulsion can be stabilized.

The invention also relates to a means for stabilizing aqueous silicone emulsions, comprising silica particles-preferably hydrophilic-associated with at least one costabilizer, preferably chosen from those mentioned above.

l'ESAAB est mise en oeuvre avec des particules anti-brouillard non cellulosiques dont la granulométrie donnée par leur Dso (en Mm) est telle que :
Dso # 10 de préférence 0,001 Dso 5 et plus préférentiellement encore 0,01 Dso 2 ces particules anti-brouillard étant incorporées dans la composition silicone liquide à raison d'au plus 30% en poids, de préférence à raison de 0,1 à 15 % en poids et plus préférentiellement encore à raison de 1 à 10% en poids. According to an interesting variant of the invention,

ESAAB is carried out with non-cellulosic anti-fog particles whose particle size given by their Dso (in Mm) is such that:
Dso # 10, preferably 0.001 Dso 5 and more preferably 0.01 Dso 2, these anti-mist particles being incorporated in the liquid silicone composition in a proportion of at most 30% by weight, preferably 0.1 to 15% by weight. % by weight and more preferably still from 1 to 10% by weight.

 Advantageously, these anti-fog particles are selected from the group comprising: - carbon black - sitz - CaCO3 - TiO2 - BaSO4 - Al2O3 - lime - talc - mica

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- quartz broyé - argiles naturelles ou synthétiques (vermiculite expansée ou non, kaolin) poudres à base de polymères (s) synthétique (s) autre (s) qu'un polymère cellulosique terres de diatomées et leurs mélanges ; le silice, le kaolin le talc, TiO2 étant particulièrement préférés ; ces particules ayant éventuellement subi un traitement de surface.

- crushed quartz - natural or synthetic clays (expanded or non-expanded vermiculite, kaolin) powders based on synthetic polymers other than a cellulosic polymer diatomaceous earth and mixtures thereof; silica, kaolin talc, TiO2 being particularly preferred; these particles having optionally undergone a surface treatment.

 The specific surface area of these BET anti-mist particles is between 0.5 m 2 / g and 500 m 2 / g, preferably between 2 and 400 m 2 / g, and more preferably between 5 and 300 m 2 / g.

 In the case where the anti-fog particles consist of silica, it should be noted that it may be colloidal silica, precipitated silica or pyrogenation silica.

A. les méthylpolysiloxanes tels que l'hexaméthyldisiloxane, l'octaméthylcyclotétrasiloxane,
B. les méthylpolysilazanes tels que l'hexaméthyldisilazane, l'hexaméthyltrisilazane,
C. les chlorosilanes tels que le diméthyldichlorosilane, le triméthylchlorosilane, le méthylvinyldichlorosilane, le diméthylvinylchlorosilane,
D. les alcoxysilanes tels que le diméthyldiméthoxy-silane, le diméthylvinyléthoxysilane, le triméthyl-méthoxysilane, l'octyltriéthoxysilane. These silicas are preferably used as they are or may alternatively, have undergone a surface treatment using organo-silicic compounds usually used for this purpose. These compounds include:

A. methylpolysiloxanes such as hexamethyldisiloxane, octamethylcyclotetrasiloxane,
B. methylpolysilazanes such as hexamethyldisilazane, hexamethyltrisilazane,
C. chlorosilanes such as dimethyldichlorosilane, trimethylchlorosilane, methylvinyldichlorosilane, dimethylvinylchlorosilane,
D. alkoxysilanes such as dimethyldimethoxysilane, dimethylvinylethoxysilane, trimethylmethoxysilane, octyltriethoxysilane.

During this treatment, the silicas can increase their starting weight to a level of 20%, preferably about 18%.

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The anti-mist particles based on synthetic polymers consist of polymers derived from conventional emulsion copolymerization process of one or more polymerizable organic monomers. These organic monomers are preferably chosen from: a) alkyl (meth) acrylates, the alkyl part of which preferably contains from 1 to 18 carbon atoms, in particular methyl acrylate and ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, amyl acrylate, lauryl acrylate, isolamyl acrylate, (2 ethyl-2) acrylate hexyl), octyl acrylate, methyl methacrylate, chloroethyl methacrylate, butyl methacrylate, (3,3-dimethylbutyl) methacrylate, ethyl methacrylate, isobutyl methacrylate, isopropyl methacrylate, phenyl methacrylate, butyl chloroacrylate, methyl chloroacrylate, ethyl chloroacrylate, isopropyl chloroacrylate, cyclohexyl chloroacrylate.

en C9-Cll), le laurate de vinyle, le benzoate de vinyle, le triméthylacétate de vinyle, le pivilate de vinyle et le trichloroacétate de vinyle. b) the α, s-ethylenically unsaturated esters of monocarboxylic acids, the acid part of which is non-polymerizable and the unsaturated part of which preferably contains 2 to 14 carbon atoms and the acid part of 2 to 12 carbon atoms; , especially vinyl acetate, vinyl propionate, vinyl butyrate, alkyl acetate, vinyl versatates (trade name for a-branched acid esters)

C9-Cll), vinyl laurate, vinyl benzoate, trimethyl vinyl acetate, vinyl pivilate and vinyl trichloroacetate.

 c) esters and hem esters of α, β-ethylenically unsaturated polycarboxylic acids containing from 4 to 24 carbon atoms, in particular dimethyl, diethyl maleate, methyl and ethyl fumarate and fumarate; (2-ethylhexyl).

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d) vinyl halogens, in particular vinyl chloride, vinyl fluoride, vinylidene chloride and vinylidene fluoride.

difluorostyrène, et le 1-vinylnaphtalène. e) vinyl aromatics preferably having at most 24 carbon atoms and chosen in particular from styrene, α-methylstyrene, 4-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methoxystyrene and 2-hydroxymethylstyrene; , 4-ethylstyrene, 4-ethoxystyrene, 3,4-dimethylstyrene, 2-chlorostyrene, 3-chlorostyrene, 4-chloro-3-methylstyrene, 4-tert-butylstryrene, 4-dichlorostyrene, 2, 6-dichlorostyrene, 2.5-

difluorostyrene, and 1-vinylnaphthalene.

f) conjugated aliphatic dienes having preferably 3 to 12 carbon atoms, in particular 1,3 butadiene, isoprene and 2-chloro-1,3-butadiene.

g) α, β-ethylenically unsaturated nitriles preferably having from 3 to 6 carbon atoms such as acrylonitrile and methacrylonitrile.

It is possible to use as PAB all other polymers, with the exception of cellulosic polymers, which are preferably in the form of powders obtained by methods known per se, for example: cryogenic grinding, prilling, spray ...

These polymer powders may be, for example, polyamide powders, polytetrafluoroethylene (PTFE).

 The mode of preparation of the liquid coating composition comprising at least one ESAAB, or even charged with anti-fog particles, is also one of the essential elements of the present invention.

Thus, it is preferable to mix at least a portion of the silicone phase with all or part of the ESAAB, or even anti-mist particles in pulverulent dry form and / or in the form of a suspension in a

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liquide (organique ou aqueux), de préférence sous forme sèche pulvérulente.

liquid (organic or aqueous), preferably in pulverulent dry form.

More specifically, the preferred mixing conditions are as follows: either all of the ESAAB is gradually mixed, or even anti-fog particles with the silicone phase in continuous or dispersed form; - or gradually mixing all the ESAAB, or even anti-fog particles with a fraction of the POS (A), this intermediate mixture being then mixed with the silicone phase, in continuous or dispersed form, including the residual fraction of the silicone phase.

More preferably still, the ESAAB silicone phase mixture or anti-fog particles is carried out using a conventional mixer, known to be dispersing in fluid media operating at room temperature.

By way of examples, mention may be made of slow dispersers, static mixers, blade mixers, single or multiple screw extruders, planetary mixers, hook mixers, slow dispersers.

 Naturally, the liquid silicone composition may comprise other additives initially contained in the silicone phase or incorporated during mixing with the ESAAB, or even the anti-fog particles.

According to a preferred method of combating mist formation, the following products are chosen as constituents of the silicone phase of the liquid coating composition: POS (A): product having units of formula:

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dans laquelle : - West un groupe alcényle, de préférence vinyle ou alkyle, - Z est un groupe hydrocarboné monovalent, exempt d'action défavorable sur l'activité du catalyseur et choisi, de préférence, parmi les groupes alkyles ayant de 1 à 8 atomes de carbone inclus, avantageusement, parmi les groupes méthyle, éthyle, propyle et 3,3, 3-trifluoropropyle et ainsi que parmi les groupes aryle et, avantageusement, parmi les radicaux xylyle et tolyle et phényle, - a est 1 ou 2, b est 0, 1 ou 2 et a + b est compris entre 1 et 3, éventuellement au moins une partie des autres motifs sont des motifs de formule moyenne :

dans laquelle Z a la même signification que ci-dessus et c a une valeur comprise entre 0 et 3, par exemple entre 1 et 3 ; les diméthylpolysiloxanes à extrémités diméthylvinylsilyle, les copolymères méthylvinyldiméthylpolysiloxanes à extrémités triméthylsilyle, les copolymères méthylvinyldiméthylpolysiloxanes à extrémités diméthylvinylsilyle, les méthylvinylpolysiloxanes cycliques, étant plus spécialement sélectionnés ; - POS (B) : produit présentant des motifs siloxyle de formule :

dans laquelle : - L est un groupe hydrocarboné monovalent, exempt d'action défavorable sur l'activité du catalyseur e choisi, de préférence, parmi les groupes alkyles

wherein: an alkenyl group, preferably vinyl or alkyl, - Z is a monovalent hydrocarbon group, which has no adverse effect on the activity of the catalyst and is preferably selected from alkyl groups having 1 to 8 atoms of carbon, advantageously, among methyl, ethyl, propyl and 3,3,3-trifluoropropyl groups and, as well as from aryl groups and, advantageously, from xylyl and tolyl and phenyl radicals, - a is 1 or 2, b is 0, 1 or 2 and a + b is between 1 and 3, optionally at least some of the other units are units of average formula:

wherein Z has the same meaning as above and ca a value between 0 and 3, for example between 1 and 3; dimethylvinylsilyl-terminated dimethylpolysiloxanes, trimethylsilyl-terminated methylvinyldimethylpolysiloxane copolymers, dimethylvinylsilyl-terminated methylvinyldimethylpolysiloxane copolymers, cyclic methylvinylpolysiloxanes being more specifically selected; POS (B): product having siloxyl units of formula:

in which: L is a monovalent hydrocarbon group, which has no adverse effect on the activity of the catalyst and is preferably chosen from among the alkyl groups;

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ayant de 1 à 8 atomes de carbone inclus et, avantageusement, parmi les groupes méthyle, éthyle, propyle et 3,3, 3-trifluoropropyle et ainsi que parmi les groupes aryles et, avantageusement, parmi les radicaux xylyle et tolyle et phényle, - d est 1 ou 2, c est 0,1 ou 2, d + c a une valeur comprise entre 1 et 3, - éventuellement, au moins une partie des autres motifs étant des motifs de formule moyenne :

dans laquelle L a la même signification que ci-dessus et g a une valeur comprise entre 0 et 3, et le poly (diméthylsiloxane) (méthylhydrogénosiloxy) (a, ro-diméthylhydrogéno) siloxane, étant plus spécialement sélectionnés.

having from 1 to 8 carbon atoms inclusive and advantageously from methyl, ethyl, propyl and 3,3,3-trifluoropropyl and also from aryl groups and, advantageously, from xylyl and tolyl and phenyl radicals, d is 1 or 2, c is 0,1 or 2, d + ca a value of between 1 and 3, - optionally, at least a part of the other units being units of average formula:

wherein L has the same meaning as above and ga value from 0 to 3, and poly (dimethylsiloxane) (methylhydrogensiloxy) (α,--dimethylhydrogen) siloxane, being more specifically selected.

 These POS can be of the type of those that crosslink at room temperature or heat by polyaddition reactions in the presence of a metal catalyst, in this case platinum-based. These are crosslinkable POS compositions called RTV ("Room Temperature Vulcanizing") or polyaddition POS compositions called EVC which is the abbreviation of "hot vulcanizable elastomer".

Two-component or one-component RTV or EVC polyaddition compositions, essentially by reaction of hydrogenosylyl groups on alkenyl sylyl groups, in the generally presence of a metal catalyst (preferably platinum), are described, for example, in US-3,220 patents. 972.3 284 406.3 436 366.3 697 473 and 4 340 709.

 According to one variant, the liquid silicone composition used may be chosen from two-component or one-component POS compositions which crosslink at room temperature by polycondensation reactions under the action of

<Desc / Clms Page number 20>

l'humidité, en présence généralement d'un catalyseur métallique, par exemple un composé de l'étain (RTV polycondensation). Ces compositions sont décrites par exemple dans les brevets US-3 065 194,3 542 901,3 779 986,4 417 042 et dans le brevet FR-2 638 752 (compositions monocomposante) et dans les brevets US-3 678 002,3 888 815,3 933 729 et 4 064 096 (compositions bicomposante).

moisture, usually in the presence of a metal catalyst, for example a compound of tin (RTV polycondensation). These compositions are described, for example, in patents US Pat. Nos. 3,065,194, 3,542,901, 3,779,986 and 417,042 and in patent FR-2,638,752 (monocomponent compositions) and in US Patents 3,678,002.3. 888,815.3,933,729 and 4,064,096 (two-component compositions).

The POS entering into these RTV polycondensation compositions are linear branched or crosslinked polysiloxanes carrying hydroxyl groups or hydrolyzable groups, for example alkoxy. Such compositions may further contain a crosslinking agent, which is, in particular, a cylinder carrying at least 3 hydrolyzable groups such as, for example, a silicate, an alkyltrialkoxysilane or an aminoalkyl trialkoxysilane.

 The liquid silicone coating composition may also comprise one or more cationically or radically crosslinkable POSs: in the presence of an effective amount of cationic initiator systems (thermal initiators and / or photoinitiators) -onium borate initiators or organometallic complexes, proton-donating organic solvents (isopropyl alcohol, benzyl alcohol, etc.)

 and / or, as the case may be, in the presence of a radical initiator, via activation by actinic radiation (UV) or by electron beams.

These POS are, for example epoxysilicones and / or vinyl ethersilicones, linear or cyclic.

Such epoxy or vinyloxyfunctional POSs are described in particular in patents DE-4,009,889, EP-0 396 130, EP-0 355 381, EP-0 105 341, FR-2 110 115 and FR-2 526 800.

The epoxy functional POSs may be prepared by hydrosylylation reactions between SiH-patterned oils and epoxy-functional compounds such as vinyl-4-cyclohexenone or allylglycidyl ether.

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Les POS vinyloxyfonctionnels peuvent être préparés par réaction d'hydrosilylation entre des huiles à motifs SiH et des composés vinyloxyfonctionnels tels que l'allylvinyléther ou l'allylvinyloxyéthoxybenzène.

Vinyloxy functional POSs may be prepared by hydrosilylation reaction between SiH-patterned oils and vinyloxy-functional compounds such as allylvinylether or allylvinyloxyethoxybenzene.

In addition to these POSs, the liquid silicone coating composition may also contain:
E. at least one adhesion promoter (E)
F. and / or at least one additive (F) common in silicone crosslinking compositions by polyaddition, polycondensation, cationic or free radical.

. les photosensibilisateurs choisis parmi les produits (poly (aromatiques)-éventuellement métalliques-et les produits hétérocycliques (phénotiazine, tétracène, périlène, anthra-cène, xantopinacole, thioxanthone... - et de manière générale pour tous les POS : * les pigments, * les a-oléfines, As regards the additives (F), mention may be made of: for the POS polyaddition RTV compositions: the retarders of the addition reaction (for example tetramethylvinyltetrasiloxane, pyridine, phosphines, phosphites, unsaturated amides and acetylenic alcohols) for POS RTV compositions or EVC: crosslinking agents such as alkyltrialkoxysilane alkyl silicates, alkyl polysilicates (methyl, ethyl silicate, isopropyl silicate, n-propyl silicate, etc.) - for crosslinkable POSs by cationic and / or radical means by activation under radiation or electron beams: epoxyether diluents, carbon black type pigments, titanium dioxide, phthalocyanine, benzimidazolone, naphthone, diazopyrazolone ...,

. the photosensitizers chosen from the products (poly (aromatic) - possibly metal-and the heterocyclic products (phenotiazine, tetracene, perilene, anthra-cene, xantopinacole, thioxanthone ... - and generally for all POS: * the pigments, the α-olefins,

<Desc / Clms Page number 22>

* les stabilisateurs, comprenant notamment les agents tensioactifs appropriés utilisables pour les compositions d'enduction en émulsion.

the stabilizers, comprising in particular the appropriate surfactants that can be used for the emulsion coating compositions.

- et qui est chargée en ESAAB, voire en particules anti- brouillard. Advantageously, the liquid silicone coating composition is a silicone oil: - which comprises one or more POS (A), optionally a compound (B) -and optionally a diluent and / or a solvent (Di) -,

- and which is loaded in ESAAB, or even in anti-fog particles.

As examples of diluent and / or solvent (Di), mention may be made of aliphatic solvents, aromatic solvents and chlorinated solvents, e. g. white spirit, ketones, advantageously methyl ethyl ketone, acetone, the alcohols, advantageously isopropanol, n-butyl alcohol, saturated, unsaturated or aromatic hydrocarbons, advantageously pentane, hexane, heptane, octane, toluene, xylene, benzene, petroleum cuts "naphthas"; C7-C8 petroleum cuts (especially gasoline E), halogenated hydrocarbons and mixtures thereof.

 According to one variant, the liquid silicone coating composition is an aqueous silicone phase emulsion based on compounds (A) and (B), and optionally filled with anti-fog particles.

These silicone emulsions are obtained in a manner known per se, for example as described in French Patent Application No. 97 16872, the contents of which are incorporated herein by reference.

 In another aspect, the invention relates to the use of ESAAB (or non-cellulosic particles) as anti-fog additives in crosslinkable liquid silicone compositions for coating flexible substrates to form crosslinked coatings. , using a

<Desc / Clms Page number 23>

dispositif d'enduction à cylindres, de manière à lutter contre l'apparition de brouillard lors de l'enduction, caractérisée en ce que l'ESAAB (voire les particules anti-brouillard) sont tels que définis ci-dessus.

roller coating device, so as to combat the appearance of fog during coating, characterized in that the ESAAB (or even the anti-fog particles) are as defined above.

 Finally, the invention also relates to a process for coating flexible supports with at least one liquid silicone precursor composition for silicone coating (s), this coating being carried out using a roll coating device, characterized in that the method of combating the appearance of mist ("misting") as defined above is used.

 It therefore appears that the invention proposes a simple, economical and reliable original means of combating the production of fog when coating flexible substrates (for example paper, film or polymer film) with a crosslinkable liquid silicone composition in roll coating devices operating at high speed. The practical industrial consequence is that the speeds of scrolling can be further increased without this phenomenon of fog harmful to the quality of the coating appearing. The control means proposed by the invention also has the non-negligible advantage of not impairing the appearance qualities, the coverage, the anti-adhesion properties, as well as the mechanical properties (rub-off) of the silicone crosslinked coating. that one seeks to obtain on at least one of the faces of the flexible support.

 In addition, the reduction of misting significantly improves the health and safety conditions for the personnel stationed with high-speed roll-fed silicone coating machines.

 The invention will be better understood in the light of the examples which follow.

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EXEMPLES Dans ces exemples, la viscosité est mesurée à l'aide d'un viscosimètre BROOKFIELD selon les indications de la norme AFNOR NFT 76 106 de mai 1982.

EXAMPLES In these examples, the viscosity is measured using a BROOKFIELD viscometer according to the indications of standard AFNOR NFT 76 106 of May 1982.

Examples 1 to 6: Table 1: Composition of Silicone Anti-Fog Emulsions (ESAAB):
TABLE 1

<Tb>
<tb> Example <SEP> Nature <SEP> Nature <SEP>% <SEP>% <SEP> Nature <SEP> surfactant <SEP>% <SEP> Size
<tb> Emulsion <SEP> Oil <SEP> oil <SEP> water <SEP> surfactant <SEP> Emulsion
<tb> / water <SEP> or <SEP> (m)
<tb> oil
<tb> 1 <SEP> Inverse <SEP> P1 <SEP> 70 <SEP> 30 <SEP> Silicone <SEP> polyether <SEP> 5 <SEP> 20
<tb> 2 <SEP> Inverse <SEP> Pl <SEP> 50 <SEP> 50 <SEP> Silica <SEP> 12, <SEP> 5 <SEP> 816
<tb> 3 <SEP> Inverse <SEP> Pl <SEP> 50 <SEP> 50 <SEP> Silica <SEP> 18 <SEP> 9
<tb>"4Inverse<SEP> PI <SEP> 50 <SEP> 50 <SEP> Sllice / Octyltrlmethoxy <SEP> 12.5 / 0, <SEP> 16 <SEP> Il, <SEP> 8
<tb> Ammonium <SEP> chloride
<tb>'Inverse <SEP> PI <SEP> 50 <SEP> 50 <SEP> Silica / Octyltrimethoxy <SEP> 12, <SEP> 5/0, <SEP> 8 <SEP> 3, <SEP> 3
<tb> Ammonium <SEP> chloride
<tb> 6 <SEP> Direct <SEP> P2 <SEP> 40 <SEP> 60 <SEP> Polyvinyl alcohol <SEP><SEP> 50, <SEP> 8
<tb> 7 <SEP> Inverse <SEP> P3 <SEP> 75 <SEP> 25 <SEP> Silica / Trideceth8 * <SEP> 24/12 <SEP> 6
<Tb>

* Le Trideceth8 est un tensioactif constitué par un alcool éthoxylé. polymère PI : polydiméthylsiloxane dont les extrémités sont bloquées par un groupe diméthylvinylsiloxy et dont la viscosité est de 600 mPa. s environ, polymère P2 : polydiméthylsiloxane dont les extrémités sont bloquées par un groupe diméthylvinylsiloxy et dont la viscosité est de 200 mPa. s environ, polymère P3 de polydiméthylsiloxane dont les extrémités sont bloquées par un groupe diméthylvinylsiloxy et dont la viscosité est de 100 mPa. s environ.

* Trideceth8 is a surfactant consisting of an ethoxylated alcohol. PI polymer: polydimethylsiloxane whose ends are blocked by a dimethylvinylsiloxy group and whose viscosity is 600 mPa. The polymer P2, polydimethylsiloxane whose ends are blocked by a dimethylvinylsiloxy group and whose viscosity is 200 mPa. about 3, polydimethylsiloxane P3 polymer whose ends are blocked by a dimethylvinylsiloxy group and whose viscosity is 100 mPa. s about.

Examples 8 to 19: Evaluation of ESAAB Emulsions To analyze and quantify the fog produced in a roll-coating device operating at high speed, the laboratory scale was

<Desc / Clms Page number 25>

dispositif à 2 rouleaux fonctionnant de manière reproductible et apte à faire défiler une bande de papier à une vitesse linéique de plus de 900m/min. Par ailleurs, un projecteur de lumière suffisamment puissant a été installé de sorte d'éclairer l'ensemble des 2 cylindres presseur/enducteur et de pouvoir observer à partir de quelle vitesse de rotation des cylindres le brouillard devient visuellement détectable.

device with 2 rollers operating in a reproducible manner and able to scroll a strip of paper at a linear speed of more than 900m / min. In addition, a sufficiently powerful light projector has been installed so as to illuminate all 2 presser / coater cylinders and to observe from what speed of rotation of the cylinders the fog becomes visually detectable.

The two pressure / coating rollers have a diameter of 10 cm. The pressure roller is covered with rubber and the chromium casting cylinder. The coating roll has been dumbbelled so that the speed of the two rolls is synchronous. The pressure roller drivable by a motor is in constant pressure contact with the coating cylinder. The silicone coating liquid is poured directly into the burner between the two rollers. The amount of fluid used is 1 ml or 0.25 ml.

Various compositions were then prepared by mixing a silicone polymer (pal, P2, P3 as defined above) and various direct or inverse emulsions.

The mixture thus obtained is homogenized with Ultra Turrax. The rotary system described in the preceding paragraph is then used on the rollers of which the preparation in question is spread. The rotational speed of the rollers is then progressively increased and the tangential speed is noted from which the appearance of the fog is visually detected.

Table 2 below summarizes the results obtained.

<Desc / Clms Page number 26>

TABLEAU 2

TABLE 2

<Tb>
<tb> Example <SEP> Polymer <SEP> Emulsions <SEP>% <SEP> VISCO <SEP> Deposit <SEP> MISTING <SEP> Differential
<tb> Pl <SEP> emulsion <SEP> (cps) <SEP> (ml) <SEP> (m / min) <SEP> MISTING <SEP> by
<tb> (i = l <SEP> or <SEP> used <SEP> report <SEP> at
<tb> i = 2) <SEP> control
<tb> Example <SEP> 8 <SEP> Polymer <SEP> 700 <SEP> l <SEP> 115
<tb> Pl
<tb> (Witness)
<tb> Example <SEP> 9 <SEP> Polymer <SEP> Example <SEP> 1 <SEP> 10 <SEP> 850 <SEP> 1 <SEP> 140 <SEP> 25
<tb> Pl
<tb> Example <SEP> Polymer <SEP> 280 <SEP> 1 <SEP> 175
<tb> 10 <SEP> Pl
<tb> Example <SEP> Polymer <SEP> Example <SEP> 2 <SEP> 6 <SEP> 300 <SEP> 1 <SEP> 260 <SEP> 85
<tb> 11 <SEP> P2
<tb> Example <SEP> Polymer <SEP> Example <SEP> 3 <SEP> 6.2 <SEP> 295 <SEP> 1 <SEP> 240 <SEP> 65
<tb> 12 <SEP> P2
<tb> Example <SEP> Polymer <SEP> Example <SEP> 3 <SEP> 9.8 <SEP> 310 <SEP> 1 <SEP> 290 <SEP> 115
<tb> 13 <SEP> P2
<tb> Example <SEP> Polymer - 275 <SEP> 0, <SEP> 25 <SEP> 265
<tb> 14 <SEP> P2
<tb> Example <SEP> Polymer <SEP> Example <SEP> 4 <SEP> 10 <SEP> 310 <SEP> 0.25 <SEP> 380 <SEP> 115
<tb> 15 <SEP> P2
<tb> Example <SEP> Polymer <SEP> Example <SEP> 5 <SEP> 10 <SEP> 310 <SEP> 0.25 <SEP> 390 <SEP> 125
<tb> 16 <SEP> P2
<tb> Example <SEP> Polymer <SEP> 275 <SEP> 0.25 <SEP> 260
<tb> 17 <SEP> P2
<tb> Example <SEP> Polymer <SEP> Example <SEP> 4 <SEP> 10 <SEP> 275 <SEP> 0.25 <SEP> 370 <SEP> 110
<tb> 18 <SEP> P2 <SEP> bis
<tb> Example <SEP> Polymer <SEP> Example <SEP> 5 <SEP> 10 <SEP> 300 <SEP> 0.25 <SEP> 365 <SEP> 105
<tb> 19 <SEP> P2 <SEP> bis
<tb> Example <SEP> Polymer <SEP> Example <SEP> 6 <SEP> 12.9 <SEP> 384 <SEP> 0.25 <SEP> 300 <SEP> 40
<tb> 20 <SEP> P2
<tb> Example <SEP> Polymer <SEP> Example <SEP> 7 <SEP> 20.7 <SEP> 436 <SEP> 0, <SEP> 25 <SEP> 410 <SEP> 150
<tb> 21 <SEP> P3
<Tb>
These results show that the addition of direct or inverse emulsion in a silicone composition makes it possible to delay the rate at which the fog appears and that, by the same token, these emulsions can be considered as fog reducing agents.

All the emulsions used directly or inversely make it possible to increase the speed of appearance of the misting (examples 9 and 20 with respect to examples 8 and 17, respectively).

Whatever the type of polymer used PI and P2, the increase in the speed of appearance of the misting is visualized.

Whatever the stabilizing system used (silicone polyether, colloidal silica with or without

<Desc / Clms Page number 27>

tensioactif cationique, colloïde protecteur), l'effet est observé (exemples 9, 11, 12, 15, 16, 20, 21 par rapport respectivement aux exemples témoins correspondants 8,10, 14 et 17). Cet effet peut être modulé suivant la teneur en émulsion introduite (exemples 12 et 13 par rapport à l'exemple 10).

cationic surfactant, protective colloid), the effect is observed (Examples 9, 11, 12, 15, 16, 20, 21 relative respectively to the corresponding control examples 8, 10, 14 and 17). This effect can be modulated according to the emulsion content introduced (Examples 12 and 13 with respect to Example 10).

It was further verified that these observations were reproducible (Examples 18 and 19 with respect to Examples 15 and 16).

Claims (17)

20% by weight of water, preferably from 20 to 90% by weight of water, and even more preferably from 20 to 70% by weight of water; and optionally with a liquid compound (D) consisting of a diluent and / or a solvent consisting of a nonorganosilicic or organosilicic organic compound, capable or not of reacting with the compound (s) (A).  - C- optionally at least one catalyst of the crosslinking reaction; characterized in that a liquid coating composition obtained by mixing: a silicone phase comprising one or more POS (A) and optionally one or more compounds (B) (crosslinking) and whose viscosity at 25 C is less than 2000 mPa. s, preferably between 100 and 1400 mPa. s, and more preferably still between 100 and 800 mPa. s; with an Aqueous Silicone Emulsion Anti-Fog (ESAAB) whose aqueous phase (pa comprises at least

1 / A method of combating the appearance of mist ("misting") during the coating of flexible substrates with at least one liquid silicone precursor composition silicone coating (s), using a device roll coating, the liquid composition comprising: - A- at least one polyorganosiloxane (POS) crosslinkable by polyaddition, by polycondensation, cationically or by radical means - B- optionally at least one cross-linking organosilicon compound  2 / A method according to claim 1, characterized in that the ESAAB is a reverse emulsion of the water-in-oil type. <Desc / Clms Page number 29>

3 / A method according to claim 1, characterized in that the ESAAB is a direct emulsion of the oil type in water. 4 / A method according to any one of claims 1 to 3, characterized in that the ESAAB comprises at least one surfactant selected from nonionic, anionic, cationic or zwitterionic.  5 / A method according to any one of claims 1 to 4, characterized in that one uses silica particles, as a means of stabilizing the ESAAB, in combination with at least one co-stabilizer of preferably selected from nonionic, anionic or cationic or even zwitterionic surfactants.  6 / A method according to any one of claims 1 to 5, characterized in that the ESAAB is associated with non-cellulosic anti-fog particles, the

 The particle size given by their D 50 (in Um) is such that Dso, preferably 0.001 <Duo'5 and more preferably still 0.01 Dso 2, these anti-mist particles being incorporated into the liquid silicone composition at the rate of at most 30% by weight, preferably from 0.1 to 15% by weight and more preferably still from 1 to 10% by weight; these anti-fog particles being preferably selected from the group comprising: - carbon black - sitz - CaCO 3 - TiO 2 - BaSO 4 - Al 2 O 3 <Desc / Clms Page number 30>  silica, kaolin, talc, TiO2 being particularly preferred; these particles having optionally undergone a surface treatment.

 - talc mica - crushed quartz natural or synthetic clays (expanded or non-expanded vermiculite, kaolin) - synthetic polymer (s) powders other than a cellulosic polymer diatomaceous earth and mixtures thereof;

 7 / A method according to any one of claims 1 to 6, characterized in that at least a portion of the silicone phase is mixed with all or part of the ESAAB.  8 / A method according to any one of claims 1 to 7, characterized in that - or is gradually mixed all of the ESAAB with the silicone phase in continuous or dispersed form; - Or gradually mixing all of the ESAAB with a fraction of the POS (A), this intermediate mixture is then mixed with the silicone phase, in continuous or dispersed form, comprising the residual fraction of the silicone phase.  9 / A method according to any one of claims 1 to 8, characterized in that the mixture silicone phase / anti-fog particles is carried out using a conventional mixer, known to be dispersant in fluid media by operating at room temperature. <Desc / Clms Page number 31>

10 / A method according to any one of claims 1 to 8, characterized in that the following products are chosen as constituents of the silicone phase: - POS (A): product having units of formula:

 wherein: - W is an alkenyl group, preferably vinyl or alkyl, Z is a monovalent hydrocarbon group, which has no adverse effect on the activity of the catalyst and is preferably selected from alkyl groups having 1 to 8 atoms of carbon, advantageously, among methyl, ethyl, propyl and 3,3,3-trifluoropropyl groups and, as well as from aryl groups and, advantageously, from xylyl and tolyl and phenyl radicals, a is 1 or 2, b is 0,1 or 2 and a + b is between 1 and 3, optionally at least some of the other units are units of average formula:

 wherein Z has the same meaning as above and c has a value between 0 and 3, for example between 1 and 3; dimethylvinylsilyl-terminated dimethylpolysiloxanes, trimethylsilyl-terminated methylvinyldimethylpolysiloxane copolymers, dimethylvinylsilyl-terminated methylvinyldimethylpolysiloxane copolymers, cyclic methylvinylpolysiloxanes being more specifically selected; <Desc / Clms Page number 32>

 POS (B): product having siloxyl units of formula:

 wherein L has the same meaning as above and g is from 0 to 3, and poly (dimethylsiloxane) (methylhydrogensiloxy) (α,--dimethylhydrogen) siloxane, being more specifically selected.

 in which: L is a monovalent hydrocarbon group, which has no adverse effect on the activity of the catalyst e preferably chosen from alkyl groups having from 1 to 8 carbon atoms inclusive and, advantageously, from methyl groups, ethyl, propyl and 3,3,3-trifluoropropyl and as well as among the aryl groups and, advantageously, among the radicals xylyl and tolyl and phenyl, d is 1 or 2, c is 0,1 or 2, d + ca a value between 1 and 3, possibly at least some of the other units being units of average formula:

 11 / A method according to any one of claims 1 to 9, characterized in that one chooses, as constituents of the silicone phase, one or more POS crosslinkable cationic or radical - in the presence of an effective amount cationic initiator systems (thermal initiators and / or photoinitiators) -onium borate initiators or organometallic complexes, proton-donating organic solvents (isopropyl alcohol, benzyl alcohol, etc.), <Desc / Clms Page number 33>  and / or, as the case may be, in the presence of a radical initiator, via activation by actinic radiation (UV) or by electron beams; these POS being preferably epoxysilicones and / or vinyl ethersilicones, linear or cyclic.

 12 / A method according to any one of claims 1 to 11, characterized in that the liquid silicone coating composition further comprises: E. at least one adhesion promoter (E) F. and / or at least one additive (F) common in silicone cross-linking compositions by polyaddition, polycondensation, cationic or free radical.  13 / A method according to any one of claims 1 to 12, characterized in that the liquid silicone composition is a silicone oil: which comprises one or more POS (A), optionally a compound (B) -and optionally a diluent and / or a solvent (Di) -,

 - and which is loaded with anti-fog particles.  14 / A method according to any one of claims 1 to 13, characterized in that the liquid silicone composition is an aqueous emulsion comprising the silicone phase based on compounds (A), optionally (B), and ESAAB.  15 / Use of at least one Sicone Fog Emulsion (ESAAB) as anti-fog additives in crosslinkable liquid silicone compositions for coating flexible substrates to form crosslinked coatings, using a device cylinder coating, so as to combat the appearance of fog during coating, characterized in that the ESAAB or ESAAB are as defined in claim 1. <Desc / Clms Page number 34>

16 / A means for stabilizing aqueous silicone emulsions characterized in that it comprises silica particles associated with at least one co-stabilizer, preferably selected from nonionic, anionic, cationic or even zwitterionic surfactants.  17 / A process for coating flexible supports with at least one liquid silicone precursor composition of silicone coating (s), this coating being carried out using a roll coating device, characterized in that one uses the misting method according to any one of claims 1 to 16.