Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
  • C08G77/04—Polysiloxanes
  • C08G77/38—Polysiloxanes modified by chemical after-treatment
  • C08G77/382—Polysiloxanes modified by chemical after-treatment containing atoms other than carbon, hydrogen, oxygen or silicon
  • C08G77/395—Polysiloxanes modified by chemical after-treatment containing atoms other than carbon, hydrogen, oxygen or silicon containing phosphorus
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
  • C08G77/04—Polysiloxanes
  • C08G77/38—Polysiloxanes modified by chemical after-treatment
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
  • C08G77/04—Polysiloxanes
  • C08G77/38—Polysiloxanes modified by chemical after-treatment
  • C08G77/382—Polysiloxanes modified by chemical after-treatment containing atoms other than carbon, hydrogen, oxygen or silicon
  • C08G77/388—Polysiloxanes modified by chemical after-treatment containing atoms other than carbon, hydrogen, oxygen or silicon containing nitrogen
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
  • C08G77/04—Polysiloxanes
  • C08G77/38—Polysiloxanes modified by chemical after-treatment
  • C08G77/382—Polysiloxanes modified by chemical after-treatment containing atoms other than carbon, hydrogen, oxygen or silicon
  • C08G77/392—Polysiloxanes modified by chemical after-treatment containing atoms other than carbon, hydrogen, oxygen or silicon containing sulfur

Definitions

• the present invention relates to new additives with antioxidant function, which can be used in particular for the stabilization of polymeric compositions, in particular non-organosilicon organic polymer compositions and silicone polyaddition or polycondensation compositions.
• the invention also relates to organic polymer compositions and to silicone compositions comprising such additives.
• the invention particularly relates to polyaddition and polycondensation silicone compositions and the elastomers derived therefrom, e.g. elastomers constituting molds.
• the invention more specifically relates to silicone elastomer molds for the reproduction of decorative and industrial objects by molding.
• compositions of organic polymers such as the silicone compositions can comprise additives with antioxidant function.
• the silicone compositions in particular the polycondensation silicone compositions, can be used for the reproduction of decorative and industrial objects by molding.
• the reproduction of objects initially consists of making a negative of the object to be copied.
• This negative (membrane) is produced here in silicone elastomer. After crosslinking the silicone, the membrane is separated from the initial object.
• This membrane constitutes the mold which will be used for the reproduction of the object to be copied.
• This type of mold is widely used for the reproduction of resin objects, such as polyester resin which is capable of faithfully reproducing the finest details.
• the mold undergoes progressive modifications: the constituents of polyester resins, and in particular styrene, diffuse in the membrane and polymerize.
• the physico-chemical structure of the mold in contact with the resins evolves: it gradually hardens while losing its non-stick character and its resistance to tearing. These modifications ultimately lead to tearing of surface fragments from the mold at the time of demolding. At this stage, the mold is no longer usable.
• the degradation mechanisms involved are diverse. They can depend just as well on criteria related to silicone elastomers as on resins or molding conditions. It is likely that the polymerization mechanism is a mechanism radical: formation of free radicals R "and ROO", initiation and propagation of radical polymerization of styrene. High styrene or peroxide contents, the exothermic nature of the resin polymerization and the presence of oxygen are aggravating factors. The diversity of factors that can influence the degradation of the silicone mold means that, to date, the solutions proposed have never been entirely satisfactory.
• One way of improving the resistance to polyester resins of a silicone mold is to introduce into the elastomer antioxidant additives which tend to inhibit radical polymerization, such as free radical inhibitors, which deactivate the R ′′ and ROO radicals. And prevent the initiation of radical polymerization.
• radical polymerization such as free radical inhibitors
• European patent application EP-A-787 766 thus proposes to improve the longevity of silicone molds by incorporating into the polycondensation composition an antioxidant additive selected from a group consisting of sterically hindered phenols, sterically hindered bisphenols, thiobisphenols sterically hindered, zinc dialkyldithiophosphates, zinc diaryldithiophosphates, aromatic amines, sterically hindered amines which may be NR-terminated 1-alkylsebacates.
• an antioxidant additive selected from a group consisting of sterically hindered phenols, sterically hindered bisphenols, thiobisphenols sterically hindered, zinc dialkyldithiophosphates, zinc diaryldithiophosphates, aromatic amines, sterically hindered amines which may be NR-terminated 1-alkylsebacates.
• the additive is chosen from the group consisting of:
• - compounds comprising more groups thioether RS q -R 'connected to a tetravalent carbon, preferably tetra (thioether) pentaerythritol, for example tetra (lauryl thiopropionate) pentaérylthritol or PETL (CAS 29 598-76-3).
• EP-A-854 167 offers several types of additives, including sterically hindered phenols, thiodipropionic acids, polysulfides, phosphonates, etc.
• silicone polymers functionalized by grafting molecules from the HALS group (FR-A-2,635,780) or from the benzotriazole group (FR-A-2,642,764).
• the former are used, for their high refractive index, in coating compositions for optical fibers, or as a lubricant for plastics such as PVC.
• the second are used for photostabilization of organic polymers.
• POS POS carrying antioxidant functions obtained by the grafting on the POS of antioxidant additives, e.g. of the free radical inhibitor type.
• a POS polymer makes it possible to stabilize non-organosilicon organic polymers, in particular thermoplastics and elastomers, whether thermoplastic or not.
• such a POS polymer is capable of ensuring a stabilization role with respect to the oxidation of the silicone compositions incorporating it, and of the elastomers thus produced, and for example of stabilization of the molds in silicone obtained by this technology.
• a POS polymer can optionally be a silicone constituent involved in the formation of the elastomeric network and therefore one or more or all of the POSs of the composition can be grafted with one or more of these additives.
• a subject of the present invention is therefore the use, as antioxidant, in particular of polymeric compositions, in particular of non-organosilicon organic polymers and / or of silicone compositions, of a POS polymer having essentially the structure of formula (1):
• the radicals R ° are chosen from: the hydrogen atom, a hydrolyzable group, a hydroxy group and a monovalent hydrocarbon group, having in particular from 1 to 20 carbon atoms; among the monovalent hydrocarbon groups, mention may in particular be made of alkyls, especially of C1-C10, alkenyls, especially of C2-C10, aryls, especially of C5-C12; e.g.: methyl, ethyl, propyl, butyl, hexyl, octyl, vinyl, phenyl, trifluoro-3,3,3-propyl; preferably at least 80% of the radicals R ° are methyl; the units U, which are identical or different, are chosen from R °, G, a hydrogen atom, a hydrolyzable group, a hydroxy group and an alkenyl group;
• G is a residue derived from an antioxidant additive, e.g. from a free radical inhibitor; by definition, G is called a stabilizing function;
• - r is an integer chosen between 0 and 400
• - s is an integer chosen between 0 and 100
• - r + s is between 0 and 500, preferably between 10 and 100
• - u is an integer between 1 and 20 and
• - t is an integer between 0 and 20, t + u> 3, preferably between 3 and 10.
• G is a function of the type of those having served to hook the precursor of the function G , and who was not involved in such a hanging.
• G can therefore be of various nature, for example H, OH, vinyl, thiol, carbinol.
• the number of these units can vary. Their number is generally between 1 and 60% of the value of s.
• the POS polymer is linear (formula (1)) and in this case more preferably POS polymers are used where s> 1.
• the radicals U are preferably different from G.
• the grafting of antioxidant functions onto POSs makes it possible to obtain additives with improved lifespan and / or of reduced diffusion coefficient, compared with the ungrafted additives from which these antioxidant functions are derived. This can also make it possible to improve the compatibility of the additive with the composition to which it is added. These properties have favorable consequences on the stability of the compositions targeted by the invention.
• the subject of the invention is such a use for the stabilization of organic polymers (and of the products formed from these compositions), in particular polyolefins, polyalkadienes, polystyrenes, polyurethanes, polyamides, polyesters , polycarbonates, polysulfones, polyether sulfones, polyether ketones, acrylic polymers, their copolymers and mixtures; it is more particularly polyolefins and polyalkadienes such than polypropylene, high density polyethylene, linear low density polyethylene, low density polyethylene, polybutadiene, their copolymers and mixtures. It aims in particular the stabilization of organic polymers against thermo-oxidative degradation.
• the POSs are free from reactive U or R ° groups, that is to say in particular from hydrolysable groups, or from H, hydroxy or alkenyl groups.
• the subject of the invention is such a use for the stabilization of silicone compositions and elastomers, with respect to oxidation. More particularly, the invention relates to the stabilization of silicone compositions and elastomers constituting molds, such as those intended for molding polyester parts, in order to prevent in particular, within the silicone elastomer, radical polymerization, eg of styrene derived from polyester resin, without interfering with the polymerization at the heart and on the surface of the molded part, eg polyester.
• molds such as those intended for molding polyester parts
• the aim is to obtain in particular a reduced diffusion coefficient of the POS additive, and / or the attenuation or even the elimination of the phenomena of inhibition on mold-mold interface, and / or increased mold life.
• the invention therefore relates to the use of these POSs to attenuate or inhibit the phenomena of inhibition at the mold-molded interface and / or to increase the longevity of the molds.
• the use is aimed at obtaining an increase in the number of moldings per mold compared to the use of conventional additives, e.g. an increase of more than 30%, 50%, or even 100%.
• the POS polymers carrying stabilizer residues may themselves be constituents of the silicone composition intended to form the elastomeric network.
• the POS polymer then carries reactive U and / or R ° groups, that is to say hydrolysable groups, or hydroxy or alkenyl groups, for example SiOH, SiH or SiVi units.
• reactive U and / or R ° groups that is to say hydrolysable groups, or hydroxy or alkenyl groups, for example SiOH, SiH or SiVi units.
• the POSs be free from such groups.
• the POS polymers according to the invention can moreover develop a plasticizer effect which contributes to maintaining the integrity of the parts, in particular silicone parts, e.g. molds.
• the stabilizing function is represented schematically using the symbol G '.
• G G '+ grafting structure (for example in this case).
• the catalyst is a conventional catalyst for the type of reaction considered.
• a hydrosilylation catalyst mention may be made of platinum-based compounds.
• Catalyst (Cat) conventional catalyst, e.g. metallic carboxylate or metal chelate
• n 1 1 to 10
• Ri ' alkyl, aryl
• R ' 7 spacer between a silicone pattern and eg an epoxy pattern
• Catalyst: acid or base R ' 8 alkyl, aryl
• G can be derived from any additive usually used as an antioxidant, for example in accordance with the preferred method of the invention, any free radical inhibitor, for example such as those described in EP- A-787 766 and FR-A-2 773 165.
• G can in particular be derived from the following compounds: - (i) sterically hindered mono- and poly-phenols, sterically hindered thio (mono- and poly-) phenols such that in particular those described in EP-A-787 766 and EP-A-854 167, bearing, or to which has been added, an unsaturated function, alcohol or ester (when the compound in question does not naturally contain the function allowing its grafting POS, an adequate function is added to the compound by methods known to those skilled in the art).
• 6-t-butylphenol 2,2'-isobutyliden-bis (4,6-dimethylphenol), 2,2'-methylen-bis (4-ethyl-6-t-butylphenol) monomethacrylatester, 1, 3.5 -trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) -benzene, 4,4'-thiobis (6-t-butyl-3-methylphenol), 4,4 ' -thio-bis (4,6-di-t-butylphenol), 2,6-di-t-butyl-p-cresol, 2-t-butyl-4-methoxyphenol, 3-t-butyl-4-methoxyphenol, alkyl-, dialky- or trialkyl-substituted phenols, with C1 to C30 alkyl, styrylphenol, di-styrylphenol, tri-styrylphenol, tetrakis (methylene 3- (3,5-di
• aromatic amines such as in particular those described in EP-A-787 766, bearing or to which are added, an unsaturated function, phenolic ether or NH.
• aromatic amines such as in particular those described in EP-A-787 766, bearing or to which are added, an unsaturated function, phenolic ether or NH.
• N-phenylbenzylamine N-phenyl-1-naphthylamine
• 4,4'- di ( ⁇ , ⁇ '-dimethylbenzyl) diphenylamine 4,4'-di (2,4,4 -triméthylpentyl) diphenyl-amine
• HALS the hindered amines called HALS of type N-OR, N-R and N-H (Hindered Amine Light Stabilizers - see Oxidation Inhibition in Organic Materials Vol. II, Chapter
• Typical commercial amines are sold under the name Tinuvin® by Ciba Geigy, Novartis or Sankyo. Mention may in particular be made of, or comprising at least one group:
• R y is hydrogen or a linear or branched C1 to C18 alkyl, optionally substituted by one or more phenyl group (s), or a C5 to C6 cycloalkyl or benzyl
• a is 0 or 1, preferably 1
• the radicals R x identical or different from each other, are chosen from alkyl radicals, linear or branched, in C1 to
• phosphines and phosphites in particular alkyl phosphites, mixed aryl and alkyl phosphites, aryl phosphites and various phosphites, bearing or to which an ester or halogen function is added, eg: triphenyl phosphite, tri-isodecylphosphite, tri-lauryl-phosphite, dilauryl-phosphite, diphenylisodecylphosphite, diphenyl-iso-octyl-phosphite, diphenyl-ethyl-2-hexyl-phosphite, diisodecylphenylphosphite, trimonononylphenylphylonylphosphonyl, 2,4-diphenylphosphonite -mononylphenyl), Tris (2,4-ditertiary-butyl-phenyl-phen
• the antioxidant additives which, when grafted on the POS, comprise at least 1 group of formula //
• additives are attached to POS either by S * or by O *. They can be obtained for example by: - transesterification from
• R 2 is H or preferably a linear or branched alkyl radical having from 1 to 15 carbon atoms
• R y is a linear or branched alkyl radical having from 1 to 40 carbon atoms; the attachment is made by the O *. - by addition of Micha ⁇ l type:
• n 4 1 to 10
• the subject of the invention is such a use for non-organosilicon organic polymers, in which G is defined as above, the piperidinyl functions described (which correspond to HALS) in FR-A-2 642 764 being excluded.
• G is defined as above, the piperidinyl functions described (which correspond to HALS) in FR-A-2 642 764 being excluded.
• Aromatic friends have a function:
• Tinuvin 312 Similar to Sanduvor (Clariant) D
• a POS polymer according to the invention can carry one or more stabilizing functions G and it preferably carries several identical or different.
• the invention of course also relates to the grafted POS polymers as described in the present application.
• the invention also relates to the compositions of stabilized organic polymers, comprising POS polymers according to the invention, the exception of those carrying piperidinyl functions according to FR-A-2 642 764.
• organic polymers mention may be made of polyolefins, polyalkadienes, polystyrenes, polyurethanes, polyamides, polyesters, polycarbonates, polysulfones, polyether sulfones, polyether ketones, acrylic polymers, their copolymers and mixtures thereof; these are more particularly polyolefins and polyalkadienes such as polypropylene, high density polyethylene, linear low density polyethylene, low density polyethylene, polybutadiene, their copolymers and mixtures.
• organic polymer compositions comprise an effective amount of POS according to the invention, in particular from 0.1 to 15%, and preferably from 0.5 to 2% relative to the stabilized composition.
• POS positron emission polymer
• the invention also relates to a process for the preparation of these organic polymer compositions stabilized by the incorporation of a sufficient quantity of POS in accordance with the invention, with the exception of those carrying piperidinyl functions according to FR-
• the invention relates to silicone compositions comprising at least one POS polymer according to the invention, the elastomers obtained by crosslinking of these compositions and the products formed, e.g. molds.
• one of the usual constituents of the silicone composition in particular a polyorganosiloxane, that is to say a constituent of the elastomeric network, constitutes the POS polymer according to the invention, that is to say say that it carries one or more G functions in accordance with the invention.
• a POS polymer which does not fall within the definition of the constituents of the elastomeric network and one or more constituents of this network which carry G functions.
• the silicone composition is a polyaddition composition
• G functions comprising radicals such as SH or NH 2 which may be poisons for the catalyst used to crosslink these compositions.
• silicone compositions comprise an effective amount of POS according to the invention, in particular from 0.1 to 15%, preferably from 0.5 to 2% relative to the stabilized composition.
• Other characteristics and particularities of the POSs to be implemented have been given above.
• the invention also relates to a process for the preparation of silicone compositions or silicone elastomers, in particular capable of being used for the production of molds, in which, in a conventional silicone elastomer precursor composition, at least one grafted silicone polymer or oil according to the invention is added.
• the invention can be applied to silicone compositions which can be crosslinked at room temperature (crosslinking can be accelerated when hot) by polyaddition or polycondensation reaction.
• the present invention applies in particular to silicone compositions which are precursors of silicone elastomers, comprising:
• A a diorganopolysiloxane oil having reactive groups chosen from i) the condensable, hydrolyzable, hydroxy and 2i) groups the alkenyl groups, preferably vinyl, linked to silicon;
• B optionally a compound chosen from the group consisting of silanes with condensable or hydrolysable groups in the case where (A) is chosen from groups i) and of diorganopolysiloxane oil carrying hydrogen atoms in the case where (A) is chosen from groups 2i);
• a first group of silicones which can be used according to the invention therefore comprises diorganopolysiloxane compositions curable into a silicone elastomer by polycondensation reactions comprising:
• the diorganopolysiloxane oils (A) which can be used in the compositions according to the invention are more particularly those corresponding to formula (3): Y n Si3.nO (SiR 2 O) x SiR 3 -nYn in which:
• R represents identical or different monovalent hydrocarbon radicals
• Y represents identical or different hydrolysable or condensable groups (other than OH), or hydroxy groups, and optionally at least one of the groups R is a function G.
• the viscosity of the oils of formula (3) is in particular between 50 and 10 6 mPa.s at 25 ° C.
• radicals R mention may be made of alkyl radicals having from 1 to 8 carbon atoms such as methyl, ethyl, n-propyl, butyl, hexyl and octyl, vinyl radicals, phenyl radicals.
• substituted R radicals mention may be made of the 3,3,3-trilfuoro-propyl, chlorophenyl and betacyanoethyl radicals.
• products of formula (3) generally used industrially, at least 60
• radicals R are methyl radicals, the other radicals generally being phenyl and / or vinyl radicals (in particular at most 1%).
• hydrolysable groups Y mention may be made of amino, acylamino, aminoxy, ketiminoxy, iminoxy, enoxy, alkoxy, alkoxy-alkylene-oxy, acyloxy and phosphato groups and, for example, among these:
• acylamino N groups the benzoyl-amino group, - for aminoxy groups: dimethylaminoxy, diethylaminoxy, dioctylaminoxy and diphenylaminoxy groups,
• - for iminoxy and ketiminoxy groups those derived from acetophenone oxime, acetone oxime, benzophenone oxime, methyl ethyl ketoxime, diisopropyl ketoxime and chlorocyclohexanone oxime
• - for alkoxy groups Y groups having from 1 to 8 carbon atoms such as methoxy, propoxy, isopropoxy, butoxy, hexyloxy and octyloxy groups
• Y the methoxy-ethylene-oxy group.
• acyloxy Y groups groups having from 1 to 8 carbon atoms such as formyloxy, acetoxy, propionyloxy and 2-ethyl hexanoyloxy groups,
• Y those derived from dimethyl phosphate groups, diethyl phosphate and dibutyl phosphate.
• condensable groups Y mention may be made of hydrogen atoms and halogen atoms, preferably chlorine.
• linear polymers consist essentially of diorganosiloxy units of formula (R 2 SiO).
• R 2 SiO diorganosiloxy units of formula (R 2 SiO).
• impurities such as RSi ⁇ 3 / 2, RSiO ⁇ / 2 and SiO 4/2 is not excluded in a proportion in particular of at most 1% relative to the number of diorganosiloxy motifs.
• R 2 SiO those of formulas can be cited:
• n is then equal to 1 and it is necessary, in order to prepare polyorganosiloxane elastomers from these polymers of formula (3), to use, in addition to the catalysts of condensation, crosslinking agents (B) which are silanes of general formula:
• groups Y are applicable to groups Y. It is desirable to use silanes of formula (4) even in the case where in the oil (A) Y does not contain hydroxy groups. In this case it is desirable to use groups Y of the oil (A) identical to the Y 'of the silane (B).
• silanes (B) of formula (4) there may be mentioned more particularly polyacyloxysilanes, polyalkoxysilanes, polyketiminoxysilanes and polyiminoxysilanes and in particular the following silanes:
• silanes (B) above combined with V, T-dihydroxylated polydiorganosiloxanes of formula (3) can be used in stable single-component compositions sheltered from air.
• CH 2 CHSi (OCH 3 ) 3 ;
• Polyalcoxypolysiloxanes may be substituted for all or part of the monomeric silanes described above, each molecule of which has at least two, preferably three, Y 'atoms; the other valences of silicon are satisfied by siloxane bonds SiO and SiR.
• polymeric crosslinking agent mention may be made of ethyl polysilicate.
• crosslinking agent of formula (4) Generally 0.1 to 20 parts by weight of crosslinking agent of formula (4) are used per 100 parts by weight of polymer of formula (3).
• crosslinking agents (B) of formula (4) are products available on the silicone market; moreover, their use in compositions which harden at room temperature is known; it is included in French patents FR-A-1 126 411, FR-A-1 179 969, FR-A-1 189 216, FR-A-1 198 749, FR-A-1 248 826, FR-A -1
• the polyorganosiloxane curable compositions of elastomer of the type described above may especially comprise from 0.001 to 10 parts by weight, preferably of 0.05 to 3 parts by weight of condensation catalyst (C) per 100 parts by weight of polysiloxane of formula (3).
• the content of condensation catalyst in mono-component compositions is generally much lower than that used in two-component compositions and can in particular be between 0.001 and 0.05 parts by weight for
• compositions according to the invention can also comprise reinforcing or semi-reinforcing or tamping fillers which are preferably chosen from siliceous fillers.
• the reinforcing fillers are preferably chosen from combustion silicas and precipitation silicas. They have in particular a specific surface, measured according to the BET methods, of at least 50 m 2 / g, preferably greater than 70 m 2 / g, an average size of the primary particles preferably less than 0.1 ⁇ m (micrometer) and an apparent density preferably less than 200 g / liter.
• silicas can be incorporated as such or after having been treated with organosilicon compounds usually used for this use. During these treatments, the silicas can increase their starting weight up to a rate of 20%, preferably around 18%.
• the treatment compounds are the siloxanes and cyclosiloxanes, eg the methylpolysiloxanes such as hexamethyldisiloxane, octamethyldisiloxane, poctamethylcyclotetrasiloxane, silazanes, eg methylpolysilazanes such as hexamethyldisilazane, chlorosilane , methylvinyldichlorosilane, dimethylvinylchlorosilane, alkoxysilanes such as dimethyldimethoxysilane, dimethylvinylethoxysilane, trimethylmethoxysilane.
• the filler can also be treated in situ, in particular with one of the above agents and more particularly with silazanes such as hexamethyldisilazane (hmdz).
• the treatment agent can be incorporated into the silicone composition before the silica, after it or in two stages.
• in situ treatment of the siliceous filler is meant the bringing together of the filler and the compatibilizing agent in the presence of at least one portion of polyorganosiloxane silicone oil (A).
• this essentially consists in introducing compatibilization agent (CA) in two stages into the preparation medium: • on the one hand, before and / or substantially simultaneously with the bringing together of at least one part of the silicone oil used with at least a portion of the siliceous filler used, this introduction of AC (portion 1) taking place in one or more times and corresponding to a proportion less than or equal to 8%, preferably 5% and, more preferably still, 3% by dry weight in relation to the total load;
• CA compatibilization agent
• portion 1 • and secondly (portion 2), after this placing in the presence of silicone oil / filler.
• the compatibilization agent for portion 1 is thus chosen from molecules which satisfy at least two criteria:
• the agent of portion 1 could be for example: - a silazane, preferably a disilazane, or mixtures thereof, hexamethyldisilazane (hmdz) being the preferred silazane and being able to be associated with divinyltetramethyldisilazane
• an amine such as ammonia or a low molecular weight alkylamine such as diethylamine
• the compatibilizers of the portion 2 can be chosen from the various silazanes and disilazanes encountered above, taken alone or as a mixture with one another, preferably from disilazanes, hexamethyldisilazane associated or not with divinyltetramethyldisilazane being particularly preferred.
• processing aids for example hydroxylated or methoxylated silicone fluids or even functional silanes.
• the semi-reinforcing or tamping fillers have a particle diameter preferably greater than 0.1 ⁇ m (micrometer) and are in particular chosen from ground quartz, calcined clays and diatomaceous earth. It is generally possible to use from 0 to 100 parts, preferably from 5 to 80 parts of filler per 100 parts of oil (A).
• silicone compositions defined generally above are well known to those skilled in the art. They are described in detail in the literature and most are commercially available. These compositions crosslink at room temperature in the presence of moisture provided by the air and / or contained in the composition. They are divided into two large families. The first family is made up of single-component or single-package compositions which are stable in storage away from air humidity and harden in elastomer to air humidity.
• the condensation catalyst (C) used is a metallic compound, generally a compound of tin, titanium or zirconium.
• these mono-component compositions are said to be acidic, neutral, or basic.
• acidic compositions mention may be made, for example, of the compositions described in patents US-A-3,035,016, US-A-3-077,465, US-A-3-133,891, US-A-3,409,573, US -A-3 438 930, US-A-3 647 917 and US-A-3 886 1 18.
• the second family which is the preferred family in the context of the present invention consists of compositions with two components or with two packages, preferably comprising an oil (A) V, T-dihydroxydiorganopolysiloxane, a silane (B) or a product originating from the partial hydrolysis of this silane, a catalyst (C) which is a metallic compound, preferably a tin compound and / or an amine, and a POS of formula (1) or (2); and / or the oil (A) and / or the compound (B) carry G functions.
• an oil (A) V, T-dihydroxydiorganopolysiloxane a silane (B) or a product originating from the partial hydrolysis of this silane
• a catalyst (C) which is a metallic compound, preferably a tin compound and / or an amine, and a POS of formula (1) or (2); and / or the oil (A) and / or the compound (B) carry G functions.
• compositions are described in US-A-3,678,002, US-A-3,888,815, US-A-3,933,729, US-A-4,064,096 and GB-A-2,032,936.
• Two-component compositions are well suited comprising: - (A): 100 parts of an oil V, T-dihydroxydiorganopolysiloxane with a viscosity of 50 to 300,000 mPa.s whose organic radicals are chosen from methyl, ethyl, vinyl, phenyl and trifluoro-3,3,3 radicals propyl, at least 60%, preferably 80%, by number being methyl radicals, up to 20% by number possibly being phenyl radicals, at most 2% being able to be vinyl radicals.
• PDMS polydimethylsiloxane
• a PDMS with trimethylsilyl termination characterized by a viscosity of 20 to 2000 mPa.s of 15 to 30 parts of a siliceous mineral filler, in particular silica, characterized by a developed surface of at least 90 m 2 / g - from 3 to 10 parts of compatibilizer, eg h dz from 1 to 5 parts of water
• Such a composition is crosslinkable when cold by adding a catalyst mixture comprising at least 1 crosslinking molecule such as an at least trifunctional alkoxysilane (eg methyl silicate, ethyl silicate, methyltrimethoxysilane) and a silicone polycondensation catalyst, such as a tin catalyst.
• a catalyst mixture comprising at least 1 crosslinking molecule such as an at least trifunctional alkoxysilane (eg methyl silicate, ethyl silicate, methyltrimethoxysilane) and a silicone polycondensation catalyst, such as a tin catalyst.
• Tin catalysts are abundantly described in the above literature; it can in particular be a tin salt of a mono- or dicarboxylic acid. These tin carboxylates are described in particular in the work of NOLL (Chemistry and Technology of Silicones, page 337, Académie Press, 1968, 2 nd edition).
• reaction product of an alkyl silicate or an alkytrialkoxysilane can also be used on dibutyltin diacetate as described in Belgian patent BE-A-842,305. phenyltrimethoxysilane - dimethyltin didecanoate couple.
• crosslinking agents (B) more particularly preferred are alkyltrialkoxysilanes, alkyl silicates and alkyl polysilicates, in which the organic radicals are alkyl radicals having from 1 to 4 carbon atoms.
• the alkyl silicates can be chosen from methyl silicate, ethyl silicate, isopropyl silicate, n-propyl silicate and polysilicates chosen from the partial hydrolysis products of these silicates; these are polymers consisting of a large proportion of units of formula (R 4 O) 3 SiOo, 5, R 4 OSiO- ⁇ , 5 , (R 4 O) 2 SiO and SiO 2 ; the symbol R 4 representing the methyl, ethyl, isopropyl, n-propyl radicals. To characterize them, it is usually based on their silica content which is established by assaying the hydrolysis product of a sample.
• polysilicate of a partially hydrolyzed ethyl silicate sold under the trademark "Ethyl Silicate-40®” by Union Carbide Corporation, or a partially hydrolyzed propyl silicate.
• the polycondensation compositions may also comprise from 10 to 130 parts by weight of polydimethylsiloxane oil (s) blocked at each of the chain ends by a (CH 3 ) 3 SiOo, 5 unit, of viscosity at 25 ° C between 10 and 5000 mPa.s, for 100 parts of oil (A).
• compositions can also optionally include adjuvants for crosslinking such as hydroxylated fluids such as water and silicones, pigments and / or specific adjuvants.
• adjuvants for crosslinking such as hydroxylated fluids such as water and silicones, pigments and / or specific adjuvants.
• compositions according to the invention can be shaped, extruded and in particular molded onto a shape which one wishes to take the imprint, then be hardened at room temperature into an elastomer at atmospheric humidity or by addition of water. Slight heating to 20 to 150 ° C can accelerate curing.
• a second group of silicones which can be used according to the invention are the polyaddition compositions curable into an elastomer by hydrosilylation reactions, characterized in that they comprise: - (A): at least one diorganopolysiloxane oil having per molecule at least two alkenyl groups, preferably vinyl, linked to silicon,
• - (B) at least one diorganopolysiloxane oil having per molecule at least three hydrogen atoms bonded to silicon
• - (C) a catalytically effective amount of a catalyst which is generally a compound of a metal from the group of platinum
• the amounts of (A) and (B) are generally chosen so that the molar ratio of the hydrogen atoms bonded to silicon in (B) to the vinyl radicals bonded to silicon in (A) is generally between 0.4 and 10 , preferably between 0.6 and 5.
• the vinyl groups in (A) and the hydrogen atoms in (B) are generally bonded to different silicon atoms.
• compositions crosslink by addition reaction (also called hydrosilylation reaction), catalyzed by a compound of a metal from the platinum group, from a vinyl group of the organopolysiloxane (A) on a hydride function of the organopolysiloxane. (B).
• the vinyl organopolysiloxane (A) can be an organopolysiloxane having siloxyl units of formula (5):
• Y is a vinyl group
• Z is a monovalent hydrocarbon group having no unfavorable action on the activity of the catalyst
• Z is generally chosen from alkyl groups having from 1 to 8 carbon atoms included such as the groups methyl, ethyl, propyl and 3,3,3-trifluoropropyl and aryl groups such as xylyl, tolyl and phenyl
• a is 1 or 2
• b is 0, 1 or 2
• a + b is between 1 and 3
• the organopolysiloxane (B) can be an organohydrogenopolysiloxane comprising siloxyl units of formula (7):
• W is a monovalent hydrocarbon group having no unfavorable action on the activity of the catalyst and corresponding to the same definition as Z, d is 1 or 2, e is 0, 1 or 2, d + a value between 1 and 3, possibly all the other units being units of average formula (8):
• radicals W which may be functions G with preferably the exclusion mentioned above.
• the organopolysiloxane (A) can only be formed of units of formula (5) or can additionally contain units of formula (6).
• Organopolysiloxane (A) can have a linear, branched, cyclic or network structure.
• the degree of polymerization is 2 or more and is generally less than 5,000.
• the organopolysiloxane (A) is linear, it has in particular a viscosity at 25 ° C of less than 500,000 mPa.s.
• Organopolysiloxanes (A) and (B) are well known and are for example described in patents US-A-3,220,972, US-A-3,284,406, US-A-3,436,366, US-A-3,697 473 and US-A-4,340,709.
• siloxyl units of formula (5) are the vinyldimethylsiloxyl unit, the vinylphenylmethylsiloxyl unit, the vinylsiloxyl unit and the vinylmethylsiloxyl unit.
• siloxyl units of formula (6) are the SiO / 2 , dimethylsiloxane, methylphenylsiloxane, diphenylsiloxane, methylsiloxane and phenylsiloxane units.
• organopolysiloxane (A) examples include dimethylpolysiloxanes with dimethylvinylsiloxyl ends, methylvinyldimethylpolysiloxane copolymers with trimethylsiloxyl ends, methylvinyldimethylpolysiloxane copolymers with dimethylvinylsiloxyl ends, methylvinylpolysiloxanes.
• the organopolysiloxane (B) can only be formed of units of formula (7) or additionally comprises units of formula (8).
• Organopolysiloxane (B) can have a linear, branched, cyclic or network structure. The degree of polymerization is 2 or more and is generally less than 5,000.
• Group W has the same meaning as group Z above.
• organopolysiloxane (B) examples include dimethylpolysiloxanes with hydrogenodimethylsilyl ends, dimethylhydrogenomethylpolysiloxane copolymers with trimethylsiloxyl ends, dimethylhydrogenomethylpolysiloxane copolymers with hydrogenodimethylsiloxyl ends, hydrogenomethylpolysiloxyl ends.
• the ratio of the number of hydrogen atoms linked to silicon in the organopolysiloxane (B) to the number of alkenyl unsaturated groups in the organopolysiloxane (A) is in particular between 0.4 and 10, preferably between 0, 6 and 5.
• the organopolysiloxane (A) and / or the organopolysiloxane with units (B) can be diluted in a non-toxic organic solvent compatible with silicones.
• the networked organopolysiloxanes (A) and (B) are commonly called silicone resins.
• the bases of polyaddition silicone compositions may contain only linear organopolysiloxanes (A) and (B) as for example those described in the aforementioned US patents: US-A-3,220,972, US-A-3,697,473 and US-A -4,340,709, or comprise both branched or networked organopolysiloxanes (A) and (B) such as, for example, those described in the aforementioned US patents: US-A-3,284,406 and US-A-3,436,366.
• the polyaddition composition may also comprise oil or oils polydimethylsiloxane (s) (in particular from 5 to 40 parts by weight) blocked at each of the chain ends by a unit (CH 3 ) 3 SiOo, 5 ; and which may possibly include G functions with preferably the exclusion mentioned above.
• Oil or oils polydimethylsiloxane (s) (in particular from 5 to 40 parts by weight) blocked at each of the chain ends by a unit (CH 3 ) 3 SiOo, 5 ; and which may possibly include G functions with preferably the exclusion mentioned above.
• Their viscosity at 25 ° C is in particular between 10 and 5000 mPa.s, for 100 parts of the organopolysiloxanes (A) + (B).
• Catalysts (C) are also well known.
• the platinum and rhodium compounds are preferably used.
• the complexes of platinum and an organic product described in American patents US-A-3,159,601, US-A-3,159,602, US-A-3,220,972 and European patents EP-A-57 can be used.
• the rhodium complexes described in the British patents can be used: GB-A-1,421,136 and GB-A-1,419,769. Platinum catalysts are preferred.
• the quantity by weight of catalyst (C) calculated by weight of platinum-metal is generally between 2 and 600 ppm, in general between 5 and 200 ppm based on the total weight of the organopolysiloxanes (A) and (B).
• polyaddition compositions preferred in the context of the present invention are those which comprise:
• A 100 parts of a diorganopolysiloxane oil blocked at each end of its chain by a vinyldiorganosiloxyle unit in which the organic radicals linked to the silicon atoms are chosen from methyl, ethyl and phenyl radicals, at least 60 mol% of these radicals being methyl radicals, of viscosity 100 to 500,000, preferably from 1,000 to 200,000 mPa.s at 25 ° C;
• compositions according to the invention may also comprise reinforcing or semi-reinforcing or tamping fillers (D), as described above in the context of the polycondensation compositions.
• Polyaddition compositions are generally stored in two packages. In fact, they crosslink as soon as all of their constituents are mixed. If it is desired to delay this crosslinking to obtain good homogenization of the active material, it is possible to add to the composition a platinum catalyst inhibitor.
• platinum catalyst inhibitors are well known. Use may in particular be made of organic amines, silazanes, organic oximes, diesters of dicarboxylic acids, acetylenic alcohols, acetylenic ketones, vinylmethylcyclopolysiloxanes (see for example US-A-3,445,420 and US-A-3,989 667).
• the inhibitor is used in an amount of 0.005 to 5 parts, preferably from 0.01 to 3 parts per 100 parts of the constituent (A).
• the silicone matrix to have a certain viscosity, in particular of the order of 5,000 to 30,000 mPa.s at 25 ° C.
• a viscosity can be obtained by a pre-crosslinking, this being blocked at the desired viscosity by the addition of an inhibitor. There is thus sufficient time to properly homogenize the active material within the silicone matrix.
• Cross-linking is then completed by heating the matrix to a temperature such that the inhibitor no longer has an effect on the catalytic action of platinum.
• compositions according to the invention can be kneaded cold as they are and be shaped, in particular molded on the shape to be reproduced.
• the invention also does not exclude associating with the POSs and compositions according to the invention non-grafted additives, in particular those described above as compounds capable of being grafted.
• Example 1 Another subject of the invention is the silicone elastomer molds capable of being obtained by crosslinking of a polyaddition or polycondensation composition as described above. It also relates to the silicone elastomer obtained.
• the present invention will now be described in more detail using embodiments taken by way of nonlimiting examples.
• motif M monofunctional motif (CH 3 ) 3 SiO 1 2
• motif D difunctional motif (CH 3 ) 2 SiO 22
• the oil, the methyl laurylthiopropionate and the butyl titanate are weighed in a 500 ml three-necked flask fitted with a mechanical stirrer; 150 ml of n-heptane are then added. The flask is heated to 120 ° C. The equilibrium is shifted towards the formation of the new esterified oil by distillation of methanol forming an azeotrope with the solvent.
• Heating is maintained until the expected quantity of methanol is completely distilled.
• the mixture is then devolatilized.
• Phenyl-1, 4-phenylenediamine (Marketed by the company ALDRICH) and 10 ml of n-octane, then this mixture is heated with stirring for 3 hours at 165 ° C.
• HPG HPG
• RHODIA SILICONES RHODIA SILICONES
• the catalyzed base mixture is homogenized and degassed.
• the product thus degassed is then poured into the appropriate molds.
• the overmolded product (which will constitute a mold) is crosslinked at room temperature (23 ° C.), and the mold is removed after 4 days.
• the characteristics of the elastomer are then as follows:
• the impact of the POSs described in the previous examples on the resistance to polyesters has been compared with that which conventional antioxidants of lower molecular weight can develop.
• the activity of the antioxidants chosen is based on the presence of thiopropionate groups and hindered phenols.
• DTDTDP and organofunctional POS are liquid at room temperature while TLPE is a solid with a melting point of around 40-45 ° C.
• additives into RTVs these additives are introduced in liquid form by direct dispersion in the base of the RTV using a propeller stirrer or manually. In the case of TLPE, this product is melted at 50 ° C before being dispersed in the RTV.
• a first type of mold used in these tests is a pin mold.
• This mold is cubic in shape (3.7 x 3.7 x 3.7 cm; wall thickness: 1.5 cm). 10 pins 1 cm high and 0.2 cm in diameter are evenly distributed on the bottom of the mold. It is the tearing of the pins arranged at the bottom of these molds which makes it possible to characterize the resistance to resins.
• a second type of mold is a "figurine mold”: it represents part of the face of a statue. It is obtained using the screed molding technique. In the context of this experimental model, tearing always occurs in the same place in a fragile area which is located in the hair of the figurine; the geometry of this fragile zone corresponds, in fact, to a strip of 1 x 2 cm and 1 mm thick.
• Shore A hardness ASTM D 2240 standard. Resistance and elongation at break: ASTM D 412 standard Tear test: ASTM D 624 standard, test piece B.
• TLPE leads to a significant deterioration in the tear resistance of the elastomer. This development is most likely due to the fact that TLPE recrystallizes after being dispersed in the molten state in the RTV; the crystals have the shape of needles.
• POS develops a plasticizing effect visible through the reduction in hardness without significantly affecting the tear strength.
• Examples 5 to 7 can be reproduced using the following composition 1) Basic mixture: Part A: 1. 420 parts of a hydroxy finished PDMS characterized by a viscosity of 18 Pa.s
• a preparation called RTVA is thus obtained.
• the additive is added as indicated in Examples 5 to 7.
• Part B parts of phenyltrimeth ⁇ xysilane
• the catalyzed mixture is prepared in a simple mixer of the central shaft type; it is used at a rate of 10 parts per 100 parts of RTVA.
• POSs according to the invention also have a protective action against UV and can be used as such.

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