WO1996016110A1

WO1996016110A1 - Silicone compounds having sterically hindered cyclic amine functions and compatibilising functions, and use thereof for light and heat stabilisation of polymers

Info

Publication number: WO1996016110A1
Application number: PCT/FR1995/001501
Authority: WO
Inventors: Philippe Karrer; Gérard Mignani
Original assignee: Rhone Poulenc Chimie
Priority date: 1994-11-18
Filing date: 1995-11-15
Publication date: 1996-05-30
Also published as: ATE184070T1; ZA959788B; IL116027A0; BR9510401A; TW340857B; FR2727120B1; CA2207112A1; AU4120396A; TR199501440A2; FR2727120A1; JPH10509756A; EP0792315A1; AR000252A1; ES2137547T3

Abstract

Mixed polyorganosiloxanes having, per molecule, (i) at least one functional siloxyl unit (I): (R1)aXSi(O)(3-a)/2, wherein R1 is a C¿1-4? alkyl radical or phenyl, X contains a secondary or tertiary cyclic amine function bound to the silicon via a -Si-A-C bond, where A is a hydrogen atom or a radical -CH2-CHR?2¿-COO- (R2 being a hydrogen atom or a C¿1-3? alkyl radical), and a is 0, 1 or 2; (2i) at least one other functional unit (II): (R?1)¿bWSi(O)(3-b)/2, wherein W is a compatibilising function, particularly an alkyl radical having more than 10 carbon atoms, and b is 0, 1 or 2; and optionally (3i) at least one other unit (III): (R1)d (H)i Si(O)¿(4-(d + e))/2?, wherein d is 0, 1, 2 or 3, e is 0 or 1, and the sum of d + e is no greater than 3. The use of such polyorganosiloxanes in polymers, in particular for improving the light-stability thereof, is also disclosed.

Description

SILICONE COMPOUNDS WITH HINDERED CYCLIC AMERICAN FUNCTIONS AND COMPATIBILIZING FUNCTIONS AND THEIR USE IN LIGHT STABILIZATION

AND THERMAL POLYMERS

The present invention relates, in its first object, to new mixed silicone compounds comprising in their structure sterically hindered cyclic amine functions linked to silicon atoms by Si-OC or Si-alkylenecarbonyloxy-C bonds, and other functions linked to silicon by compatibilizing Si-C bonds. It also relates, in a second object, to processes for the preparation of said silicone compounds. It also relates, in a third object, to the use of such compounds in polymers to improve their resistance against degradation under the effect of ultra-violet (UV) radiation, oxygen in the air and heat. . Indeed, organic polymers, and more particularly polyolefins and polyalkadienes, undergo degradation when they are subjected to external agents and in particular to the combined action of air and solar ultraviolet radiation.

This degradation is generally limited by the introduction into the polymer of small amounts of stabilizing agents. Among these anti-UV stabilizers, sterically hindered amines, in particular tetramethyl-2,2,6,6 piperidines, are currently among the most effective.

However, in practice, one of the major problems relating to the use of these anti-UV stabilizers is to obtain a good compromise between their effectiveness, which implies their mobility within the polymer, and the permanence of their action, which involves the use of high molecular weight molecules having excellent compatibility with the polymers to be stabilized.

It has been proposed in the prior art to use advantageously polyorganosiloxanes carrying sterically hindered piperidinyl functions. As documents illustrating this prior state, mention may for example be made of patent documents JP-A-01/096259, EP-A-0 338 393,

EP-A-0 343717, EP-A-0 358 190, EP-A-0 388 321 and EP-A-0 491 659. In these documents, organopolysiloxanes are described which carry sterically hindered piperidinyl functions of which the piperidinyl group can be linked to the silicon atom by a Si-OC bond (cf. in particular EP-A-0-343 717 and EP-A-0 358 190) or a Si-alkylene carbonyloxy-C bond (cf. in particular EP -A-0 358 190, EP-A-0 388 321 and EP-A-0 491 659). Continuing work in this technical field, the Applicant has found new mixed polyorganosiloxanes carrying a share of sterically hindered amine function (s) linked to silicon by a single Si-OC bond or Si-alkylene carboxy-C, and on the other hand of particular function (s) with compatibilizing action linked to silicon by an Si-C bond, which are endowed with useful properties for improving the resistance of polymers against their degradation under the effect of UV radiation, oxygen in the air and heat.

More precisely, the present invention relates in its first object to a polyorganosiloxane comprising per molecule at least 3 siloxy units, of which: - at least one functional siloxyl unit of formula:

in which :

• the symbols R ¹ are identical or different and represent a monovalent hydrocarbon radical chosen from alkyl radicals, linear or branched, having from 1 to 4 carbon atoms and phenyl;

• the symbol X represents a monovalent group of formula -A-Z where:

• A is a divalent radical chosen from an oxygen atom and a radical of formula -CH2-CHR2-COO- with R ^ being a hydrogen atom or an alkyl radical, linear or branched having from 1 to 3 carbon atoms , the free valence carried by the carbon atom being linked to the silicon atom;

• the symbol Z represents a monovalent group, the free valence of which is carried by a carbon atom, comprising a secondary or tertiary amine function, included in a cyclic hydrocarbon chain comprising from 8 to 30 carbon atoms, in which the two atoms cyclic carbon located in the α and ά positions with respect to the cyclic nitrogen atom do not contain a hydrogen atom;

• a is a number chosen from 0, 1 and 2; and

- at least one other functional siloxyl unit of formula:

(F?) _B WSi (O) _{3 b} (II)

in which :

• the symbols R ¹ have the same meanings as those given above with regard to formula (I); • the symbol W represents a monovalent group with a compatibilizing function chosen from: an alkyl radical, linear or branched, having more than 10 carbon atoms; a radical of formula -R ^ -COO-R ^ in which R3 represents an alkylene radical, linear or branched, having 5 to 20 carbon atoms and R ⁴ represents an alkyl radical, linear or branched, having 1 to 12 atoms of carbon ; a radical of formula

-R5-O- (R ⁶ -O) _C -R ⁷ in which R ⁵ represents an alkylene radical, linear or branched, having 3 to 15 carbon atoms, R> represents an alkylene radical, linear or branched, having 1 to 3 carbon atoms, c is a number from 0 to 10 and R ⁷ represents a hydrogen atom, a linear or branched alkyl radical having from 1 to 12 carbon atoms or an acyl radical -CO-R ^ where R ** represents a linear or branched alkyl radical having from 1 to 11 carbon atoms;

• b is a number chosen from 0, 1 and 2.

The polyorganosiloxane comprises, optionally in addition, at least one other siloxyl unit of formula:

⁽ < ^H > _e ^If <°> 4 g ^ ^(m)

2

in which :

• the symbols R ¹ have the same meanings as those given above with regard to formula (I);

• d is a number chosen from 0, 1, 2 and 3;

• e is a number chosen from 0 and 1;

• the sum d + e is at most equal to 3.

The siloxy units of formula (I) when there are more than two, can be identical or different from one another; the same remark also applies to the siloxyl units of formulas (II) and (III).

In the present brief, it will be understood that we define by:

- "amino functions": the monovalent Z groups not equipped with the ball joint A by means of which they are linked to the silicon atoms; - "compatibilizing functions": the monovalent groups W which are directly linked to the silicon atoms (in this case, Si-C bonds are formed);

- "organopolysiloxanes with an oxygen ball joint": the mixed polymers according to the invention in the structure of which the amino functions are linked to the silicon atoms via the ball joint A = -O- (in this case, Si bonds are formed -OC); - "organopolysiloxanes with a carboxylate ball joint": the mixed polymers according to the invention in the structure of which the amino functions are linked to the silicon atoms by through the ball joint A = -CH2-CHR2-COO- (in this case, Si-CH ₂ -CHR ² -COO-C bonds are formed).

Given the values that the symbols a, b, d and e can take, it should also be understood that the mixed polyorganosiloxanes according to the invention can therefore have a linear, cyclic, branched structure (resin) or a mixture of these structures. In the case of linear polymers, these may optionally have up to 50 mol% of branching ["T" (RSiθ3 / 2) and / or "Q" type units

(SiO _4/2 )].

When polyorganosiloxane resins are concerned, these consist of at least two different types of siloxyl units, namely "M" (R3SiO- | / 2) and / or "T" units and optionally units "D" (R2Siθ2 / 2). ; the ratio number of units "M" / number of units "Q" and or "T" is generally between 4/1 and 0.5 / 1, and the ratio number of units "D" / number of units "Q "and / or" T ^* is generally between 0 to 100/1. Advantageously, the numbers of the units of formulas (I), (II) and possibly (III) are such that the mixed polyorganosiloxanes according to the invention contain:

- At least 0.5 mol%, preferably from 10 to 90 mol%, of amino functions, and - at least 0.5 mol%, preferably from 10 to 90 mol%, of compatibilizing functions. The molar% indicated express the number of moles of functions per 100 silicon atoms.

The preferred R 1 radicals are: methyl, ethyl, n-propyl, isopropyl, n-butyl; more preferably, at least 80 mol% of the radicals R ¹ are methyls.

The preferred carboxylate patella is chosen from the divalent radicals -CH2-CH2- COO- and -CH ₂ -CH (CH ₃ ) -COO-.

The preferred amino functions Z are chosen from amino, secondary or tertiary functions, included in a cyclic hydrocarbon chain, of formula:

in which : The radicals R ⁹ , identical or different from one another, are chosen from alkyl radicals, linear or branched, having from 1 to 3 carbon atoms, phenyl and benzyl,

R ¹⁰ is chosen from a hydrogen atom, alkyl radicals, linear or branched, having from 1 to 12 carbon atoms, alkylcarbonyl radicals in which the alkyl residue is a linear or branched residue having from 1 to 8 carbon atoms, phenyl and benzyl radicals and an O- radical;

• h is a number chosen from 0 and 1.

More preferably, the amino functions Z are chosen from those of formula (IV) in which the radicals R ⁹ are methyl, the radical R ¹ 0 represents a hydrogen atom or a methyl radical and h is a number equal to 1. The preferred compatibilizing functions W are chosen: from an alkyl radical, linear or branched, having 11 to 30 carbon atoms; a radical of formula -R3-COO-R ⁴ in which R ^ represents an alkylene radical, linear or branched, having 8 to 12 carbon atoms and R ⁴ represents an alkyl radical, linear or branched, having 1 to 6 atoms of carbon ; a radical of formula -R ⁵ -O- (R6-O) _c -R ⁷ in which R ⁵ represents an alkylene radical, linear or branched, having 9 to 12 carbon atoms, R ^ represents a linear or branched alkylene radical having from 2 to 3 carbon atoms, c is a number from 0 to 6 and R represents a hydrogen atom, an alkyl radical, linear or branched, having from 1 to 6 carbon atoms or an acyl radical -CO-R8 WHERE R8 represents an alkyl radical, linear or branched, having from 1 to 3 carbon atoms.

More preferably, the compatibilizing functions W are chosen from the radicals n-undecyl, n-dodecyl, n-tridecyl, methyl or ethyl decamethylene carboxylate. The present invention, taken in its first object, aims even more precisely:

- mixed, linear, statistical, block or block polydiorganosiloxane copolymers, of average formula:

(NOT)

in which :

• the symbols R ¹ , X and W have the general meanings given above with regard to the formulas (I) and (II); the symbols Y represents a monovalent radical chosen from R ¹ , X, W and a hydrogen atom; m is an integer or fractional number ranging from 0 to 180; n is an integer or fraction ranging from 0 to 180; p is an integer or fraction ranging from 0 to 10; q is an integer or fraction ranging from 0 to 100; with the conditions under which:

- if m and n are different from 0: the sum m + n + p + q is in the range from 5 to 200; the ratio 100 m / m + n + p + q + 2 ≥ 0.5; and the ratio 100 n / m + n + p + q + 2 ≥ 0.5, this ratio being identical to or different from the previous ratio;

- if m = 0 and n is different from 0: at least one of the substituents Y represents the radical X; the sum m + n + p + q is in the range from 5 to 100; and the ratio 100 n / m + n + p + q + 2 ≥ 0.5;

- if m is different from 0 and n = 0: at least one of the substituents Y represents the radical W; the sum m + n + p + q is in the range from 5 to 100; and the ratio 100 m / m + n + p + q + 2 ≥ 0.5; and

- if m = 0 and n = 0: the sum p + q is in the range from 5 to 100; one of the substituents Y being the radical X; and the other substituent Y being the radical W;

and those of medium formula:

in which :

• the symbols R ^, X and W have the general meanings given above with regard to formulas (I) and (II);

• r is a whole or fractional number ranging from 1 to 9;

• s is a whole or fractional number ranging from 1 to 9; • t is a whole or fractional number ranging from 0 to 0.5;

• u is a whole or fractional number ranging from 0 to 5;

• the sum r + s + 1 + u is in the range from 3 to 10.

The polymers of formula (V) which are preferred (so-called PL1 polymers) or very preferred (so-called PL2 polymers), are those for which: * according to a first method: the symbols Y represent R ^; m is an integer or fraction ranging from 1 to 90; n is a whole or fractional number ranging from 1 to 90 p is a whole or fractional number ranging from 0 to 5; q is an integer or fraction ranging from 0 to 50; the sum m + n + p + q is a whole or fractional number ranging from 10 to 100; the ratio 100 m / m + n + p + q + 2 is in the range from 10 to 90; the ratio 100 n / m + n + p + q + 2 is in the range from 10 to 90, this ratio being identical or different from the previous ratio; “The radicals R ¹ , X and W simultaneously have the preferred definitions (in the case of polymers PL1) or more preferred definitions (in the case of polymers PL2) given above with respect to each of them; * according to a second method:

• m = 0 and n = 0; “One of the substituents Y is the radical X, while the other substituent Y is the radical W;

• P = 0;

• q is a whole or fractional number ranging from 5 to 10;

• the radicals R ¹ , X and W simultaneously have the preferred definitions (in the case of PL1 polymers) or the more preferred definitions (in the case of PL2 polymers) given above with respect to each of them.

The polymers of formula (VI) which are preferred (so-called PC1 polymers) or very preferred (so-called PC2 polymers), are those for which: r is an integer or fractional number ranging from 1 to 4.5; • s is a whole or fractional number ranging from 1 to 4.5; t is an integer or fraction ranging from 0 to 0.25; u is a whole or fractional number ranging from 0 to 2.5; the sum r + s + 1 + u is a whole or fractional number ranging from 3 to 5; the radicals R ¹ , X and W simultaneously have the preferred definitions (in the case of PC1 polymers) or the more preferred definitions (in the case of PC2 polymers) given above with respect to each of them.

Advantageously, the mixed organopolysiloxanes of the invention with an oxygen ball can be obtained from, and this constitutes a first modality of the second subject of the invention: • of the corresponding organohydrogenopolysiloxanes (H), which are free of function (s) Z amine (s) equipped with the oxygen patella and function (s)

^• W compatibilizer (s), • hydroxylated organic compound (s) (Ψ) from which the Z-amine function (s) equipped with the oxygen patella are derived,

• ethylenically unsaturated compound (s) at the end of the chain Ξ from which the W function (s) are derived. Thus, the mixed polyorganosiloxanes of the invention with an oxygen ball joint can be obtained by simultaneous dehydrogenocondensation and addition (hydrosilylation) reaction or, preferably, by successive dehydrogenocondensation and addition (hydrosilylation) reactions, this from: corresponding organohydrogenopolysiloxanes (H) free of the Z functions equipped with the oxygen patella and W, of the organic compound (s) hydroxylated (s) (Ψ) from which derive (s) the Z function (s) equipped with the oxygen patella, and ethylenically unsaturated compound (s) at the end of the chain (Ξ) from which the W function (s) are derived.

These dehydrogenocondensation and hydrosilylation reactions can be carried out at a temperature of the order of 20 to 200 ° C, preferably of the order of 60 to 120 ° C, in the presence of a metal-based catalyst. platinum group; mention may be made in particular of the platinum derivatives and complexes described in US-A-3,715,334, US-A-3,814,730, US-A-3,159,601, US-A-3,159,662.

The amounts of catalyst used are of the order of 1 to 300 parts per million, expressed as metal relative to the reaction medium. In the definition of the "mole of (Ψ) ', we will consider as elementary entity the OH function capable of reacting with (H) by dehydrogenocondensation. Similarly in the definition of" mole of (Ξ) ", we will consider as entity elementary olefinic unsaturation capable of reacting with (H) by hydrosilylation. The quantities of reagents which can be used generally correspond to a molar ratio [(Ξ) + (Ψ)] / SiH [of (H)] which is on the order of 1 to 5, preferably on the order of 1 to 2.

The dehydrogenocondensation and hydrosilylation reactions can take place in bulk or, preferably, within a volatile organic solvent such as toluene, xylene, methylcyclohexane, tetrahydrofuran, heptane, octane or the isopropanol; the reaction medium can also contain a buffering agent consisting in particular of an alkaline salt of a monocarboxylic acid such as for example sodium acetate.

At the end of the reactions, the crude mixed polyorganosiloxanes which are obtained can be purified in particular by passing over a column filled with an ion exchange resin and / or by simple devolatilization of the reactants introduced in excess and optionally of the solvent used, by heating operated between 100 and 180 ° C under reduced pressure. The organohydrogenopolysiloxanes (H) used for example in the preparation of linear mixed polydiorganosiloxanes of formula (V) are those of formula:

(NÎI)

in which :

• the symbols R ¹ and q have the general or preferential meanings given above with regard to the formula (V);

• the symbols Y 'represent R ¹ or a hydrogen atom;

• v is an integer or fractional number equal to m + n + p;

• with the condition that, if v = 0, q is a number in the range from 5 to 100 and the two radicals Y 'represent a hydrogen atom.

The organohydrogenopolysiloxanes (H) used for example in the preparation of the cyclic mixed polydiorganosiloxanes of formula (VI) are those of formula:

in which :

• the symbols R ^ and u have the general or preferential meanings given above with regard to the formula (VI);

• w is an integer or fractional number equal to r + s + t;

• the sum u + w is in the range from 3 to 10.

Such organohydrogenpolysiloxanes (H) of formulas (VII) and (VIII) are known in the literature and, for some, they are commercially available.

The hydroxylated organic compounds (Ψ), from which the Z functions equipped with the oxygen ball joint are derived (or also: from which the monovalent groups X are derived), are preferably those of formula:

in which the symbols R ⁹ , R ¹⁰ and h have the general or preferential meanings given above with regard to the formula (IV).

As compounds (Ψ), there may be mentioned as examples: 4-hydroxy-2,2,2,6,6 piperidine tetramethyl, 4-hydroxy-1,2,2,6,6,6 piperidine hydroxy. The unsaturated compounds (Ξ), from which the W functions are derived, are compounds having ethylenic unsaturation, located at the end of the chain, capable of reacting in hydrosilylation in the presence of a catalyst based on a platinum group metal. As compounds (Ξ), there may be mentioned as examples: undecene-1, dodecene-1, tridecene-1, methyl or ethyl undeceneate. Advantageously, the mixed organopolysiloxanes of the invention with a carboxylate patella can be obtained from, and this contributes to a second modality of the second object of the invention,:

• corresponding organohydrogenpolysilanes (H), which are free of Z amino function (s) equipped with the carboxylate patella and of W compatibilizing function (s),

• organic compound (s) ethylenically unsaturated (s) at the end of the chain (ive ") from which derive (s) the function (s) of amine (s) Z equipped (s) of the carboxylate patella,

• ethylenically unsaturated compound (s) at the end of the chain (Ξ) from which the W function (s) are derived.

Thus, the mixed polyorganosiloxanes of the invention with a carboxylate ball joint can be obtained by reaction of simultaneous or successive additions (hydrosilylations), this from: corresponding organohydrogenpolysilanes (H) free from the Z functions equipped with the ball joint carboxylate and W , of the ethylenically unsaturated organic compound (s) at the end of the chain (Ψ ") from which the Z function (s) equipped with the carboxylate patella are derived , and (or) ethylenically unsaturated compound (s) at the end of the chain (Ξ) from which the W function (s) are derived.

Said simultaneous or successive hydrosilylation reactions can be carried out under the same operating conditions (in particular: nature and amount of catalyst; reaction temperatures; nature of optional solvents) as those described above in the context of the dehydrogenocondensation and additions to the preparation of mixed polyorganosiloxanes with oxygen ball joints. According to a preferred method, said simultaneous or successive hydrosilylation reactions are carried out in the presence of an agent for inhibiting radical polymerization chosen in particular from: alkylated or aikoxylated monophenols [such as, for example, para-methoxyphenol, bis (ditertiobutyl-3, 5 4-hydroxyphenyDmethane and their mixtures]. The amount by weight of such an agent, expressed relative to the weight of the reaction medium, is generally between 0.001% and 0J%. In the definition of the "mole of (Ψ ')", we will consider here as elementary entity the olefinic unsaturation capable of reacting with (H) by hydrosilylation; the molar ratio [(Ψ ') + (Ξ)] / SiH [of (H))] also varies between 1 and 5 and, preferably between 1 and 2.

The unsaturated organic compounds (Ψ ') from which the Z functions equipped with the carboxylate ball joint are derived (or also: from which the monovalent groups X are derived) are preferably those of formula:

in which the symbols R ² , R9, R10 and h have the general or preferential meanings given above with regard to the definition of the symbol X and of the formula (IV).

As compounds (Ψ ′), there may be mentioned as examples: tetramethyl-2,2,6,6 piperidinyl-4 (meth) acrylate, 1,2-pentamethyl-1,2,6,6 (meth) acrylate , 6 piperidinyl-4. These compounds are known in the literature (cf. in particular W. LAU et al., J. Polym. Sci. Part A: Polym. Chem., 30 (1992) pages 983 et seq.) And they can be prepared by reaction of piperidinol compounds on methyl (meth) acrylate in the presence of a catalyst based on a metal alcoholate.

The mixed polyorganosiloxanes according to the invention can be used as stabilizers against the oxidative and thermal light degradation of organic polymers, and this constitutes the third subject of the invention. By way of example of such organic polymers, mention may be made of polyolefins, polyurethanes, polyamides, polyesters, polycarbonates, polysulfones, polyether sulfones, polyether ketones, acrylic polymers, their copolymers and their mixtures. .

Among these polymers, the compounds of the invention have a more particularly effective action with polyolefins and polyalkadienes such as polypropylene, high density polyethylene, linear low density polyethylene, low density polyethylene, polybutadiene, their copolymers and their mixtures. Given the wide possibilities of variations in the relative numbers of the different siloxyl units present in the siloxane chain of the mixed compounds of the invention, these said compounds can be easily adaptable to the different problems to be solved. Yet another object of the present invention therefore consists in organic polymer compositions stabilized against the harmful effects of heat and UV by an effective amount of at least one mixed polyorganosiloxane compound. Usually these compositions contain from 0.04 to 20 milliequivalents depending on the sterically hindered amine (s) per 100 g of polymer to be stabilized. Preferably, the stabilized polymer compositions according to the invention contain from 0.20 to 4 milliequivalents depending on the sterically hindered amine function (s) per 100 g of polymer.

By way of indication, generally the stabilized polymeric compositions contain from 0.01% to 5% by weight of mixed polyorganosiloxane compound relative to the polymer.

The addition of the mixed polyorganosiloxane compounds can be carried out during or after the preparation of the polymers.

These compositions can also contain all the additives and stabilizers usually used with the polymers they contain. Thus, the following stabilizers and additives can be used: antioxidants such as alkylated monophenols, alkylated hydroquinones, hydroxylated diphenyl sulfides, alkylidene-bisphenols, benzylic compounds, acylamino-phenols, esters or amides (3,5-4-hydroxy-4-hydroxyphenyl) -3-propionic acid; esters of (3,5-dicyclohexyl-3,5-hydroxy-4-phenyl) -3-propionic acid; light stabilizers such as optionally substituted benzoic acid esters, acrylic esters, nickel compounds, oxalamides; phosphites and phosphonites; metal deactivators; peroxide-destroying compounds; polyamide stabilizers; nucleating agents; fillers and reinforcing agents; other additives such as, for example, plasticizers, pigments, optical brighteners, flame retardants.

The polymer compositions thus stabilized can be applied in the most varied forms, for example in the form of molded articles, sheets, fibers, cellular materials (foam), profiles or coating products, or as film-forming agents. (binders) for paints, varnishes, glues or cements. The following examples illustrate the present invention. In these examples, the theoretical concentration of amino functions Z. expressed in milliequivalents (meq) per 100 g of silicone oil is understood to mean the concentration that silicone oil would have if all of the amino functions involved were grafted.

Example 1

Example of preparation of a mixed orαanooolvsiloxanβ with an oxygen ball joint In a 250 cm ³ reactor, equipped with a central stirring system and the internal volume of which is maintained under an atmosphere of dry nitrogen, 25 g (0J59 mole) are introduced. ) of 4,2-hydroxy-2,2,6,6 tetramethyl piperidine, 100 cm ³ of dry toluene, 0.01 g of sodium acetate and 22 nm ³ (or μl) of a solution in divinyltetramethyldisiloxane a platinum complex at 12% by weight of platinum ligated with divinyltetramethyldisiloxane (Karstedt catalyst).

The reaction medium is brought to 100 ° C., then 20 g of a polymethylhydrogenosiloxane oil (ie 0.316 mole of Si-H functions) are poured over a period of 3 hours, the characteristics of which are as follows:

• Mn = 3160 g;

• 1580 meq. H / 100 g;

• medium structure:

After pouring the oil with hydrogenosilyl functions in 3 hours, the reaction medium is left to react at 100 ° C. for 24 hours. At the end of this time, the transformation rate of the hydrogenosilyl functions is 34% (in moles).

75 g (0.44 mol) of dodecene-1 at 95% by weight are then added progressively by casting over a period of one hour. After pouring the dodecene, the reaction medium is left to react at 100 ° C. for 8 hours. The transformation rate of the hydrogenosilyl functions is complete. The reaction medium is cooled to room temperature (23 ° C), then it is washed by extraction with 100 cm ³ of water. The residual organic phase is concentrated using a rotary evaporator, heating to 160 ° C, under a reduced pressure of 0.67.10 ² Pa, for 3 hours. 65 g of a clear oil are thus recovered, the characteristics of which are as follows: • Mn ≈ 11300 g; 178.5 meq. amino functions Z / 100 g, for a theory of 222 meq / 100 g (this basicity index is measured by titration of the oil obtained by means of a 0.02 N perchloric acid solution); average oil structure:

proportion of Z functions: 38.5% (in moles of functions per 100 silicon atoms); proportion of W functions: 57.5%.

Example 2

Example of preparation of a mixed oroanopolvsiloxane with an oxygen ball joint

In a reactor of 250 cm ^3, equipped as in Example 1 was charged with 27.3 g (0J 59 mol) of hydroxy-4-pentamethyl-1, 2,2,6,6 and 100 cm ³ of toluene containing 0.012 g of sodium acetate. 60 nm ³ (or μl) of the Karstedt catalyst solution described in Example 1 are added in two batches.

The reaction medium is brought to 90 ° C., then 20 g of the polymethylhydrogenosiloxane oil used in Example 1 are poured in gradually over a period of 3 hours (ie 0.316 mol of Si-H functions).

After pouring the oil with hydrogenosilyl functions in 3 hours, the reaction medium is left to react at 90 ° C. for 24 hours. At the end of this time, the transformation rate of the hydrogenosilyl functions is 44.3% (in moles).

60 g (0.356 mol) of dodecene-1 at 95% by weight are then added progressively by casting over a period of 1 hour. After having poured the dodecene, the reaction medium is allowed to react brought to 100 ° C. for 6 hours. The transformation rate of the hydrogenosilyl functions is complete. 2 g of ion exchange resin commercially available under the registered trademark Amberlite A21 are then added, and the reaction medium is left to react, cooled to 80 ° C., for 3 hours, then it is filtered on a "milliport" membrane ( 0.2 μm porosity). The product obtained is then devolatilized for 2 hours at 160 ° C under a reduced pressure of 0.67J0 ² Pa. 32 g of a clear oil are thus recovered, the characteristics of which are as follows:. Mn = 11300 g;

• 197.8 meq. amino functions Z / 100 g, for a theory of 219 meq / 100 g;

• average oil structure:

.

• proportion of Z functions: 42.3% (in moles of functions per 100 silicon atoms);

• proportion of W functions: 53.7%.

Example 3

Example of preparation of a mixed oroanopolysiloxane with a carboxylate ball joint

1) • Preparation of tetramethvl-2.2-6.6 pioeridinvle-4 methacrvlate:

0.6 g (0.024 mole) of magnesium is introduced into a 250 cm ³ reactor, fitted with a central mechanical stirrer, a thermometer and a thermally insulated distillation column 45 cm in height, and the nitrogen reactor sky; then 10 cm ³ of dry methanol and 0.5 g of dibromo-1, 2 ethane are introduced. The reaction medium is brought to 45 ° C., there is formation of hydrogen and magnesium dimethoxylate. Once the evolution of hydrogen is complete, 40 g (0.25 mole) of 4-hydroxy-2,2,6,6 piperidine-hydroxy, then 142 g (1.42 mole) of methyl methacrylate (title mass: 99.8%), and the reaction medium is brought to its reflux temperature. The methanol formed distills. Once the methanol distillation is complete, the reaction medium is allowed to cool to room temperature (23 ° C.), then it is poured into 660 cm ³ of water. The mixture obtained is filtered through “kieselguhr” type earth available commercially under the trademark Clarcel DIT 2R. The two phases are separated and the aqueous phase is extracted with 3 times 200 cm ³ of methyl methacrylate. After washing all of the organic phases with 50 cm ³ of water and drying over Na2SO, the organic medium is concentrated using a rotary evaporator; 55.3 g of a light yellow solid are thus recovered (yield of isolated product: 88.6% by weight relative to the quantity of piperidinol used). The solid product obtained is recrystallized using a mixture of 20 cm ³ of acetone with 10 cm ³ of water. After drying at room temperature (23 ° C.) at 1.33 × 10 ² Pa, 49J g of white solid are recovered, the melting point of which is 60 ° C. (measured by DSC analysis). The yield of recrystallized product is 80%. NMR and infrared analyzes confirm the structure of the expected product.

2) Preparation of mixed oroanopolvsiloxane:

13.6 g of dry toluene and 0.003 g of sodium acetate are introduced into a 50 cm ³ reactor, equipped with a stirring system and the internal volume of which is maintained under an atmosphere of dry nitrogen. 'We bring to 110 ° C. Then 4.5 nm ³ (4.5 μl) of the Karstedt catalyst solution described in Example 1 is introduced.

Then poured simultaneously, over a period of 80 minutes, maintaining the temperature at 110 ° C, on the one hand a solution of 12.88 g (0.057 mole) of tetraméhyl-2,2,6,6 piperidinyl methacrylate- 4 and 0J g of paramethoxyphenol in 9.5 cm ³ of dry toluene, and on the other hand 5.25 g of the polymethylhydrogenosiloxane oil used in Example 1 (0.083 mole of Si-H functions).

After pouring the oil in, it is observed that the rate of transformation of the hydrogenosilyl functions is 70%. Then again 4.5 nm ³ (4.5 μl) of the Karstedt catalyst solution is introduced, then, gradually over a period of 20 minutes, 8J 3 g (0.048 mole) of dodecene-1 at 95% by weight maintaining the temperature at 110 ° C. After pouring in the dodecene, the reaction medium is left to react at 110 ° C. for 6 hours. At the end of this time, the transformation rate of the hydrogenosilyl functions is 100%.

The product obtained is then devolatilized for 2 hours at 138 ° C under a reduced pressure of 0.399.10 ² Pa. 20.12 g of a very clear yellow limpid oil are thus recovered, the characteristics of which are as follows: Mn = 13420 g;

248.3 meq. of amino functions Z / 100 g, for a theory of 258 meq 100 g average structure of the oil:

)

• in addition, the nuclear magnetic resonance reveals the presence of 3.3 mol% of T units;

• proportion of Z functions: 64% (in moles of functions per 100 silicon atoms);

• proportion of W functions: 32%.

Example 4

Example of preparation of a mixed orpanopolvsiloxane with a carboxylate ball joint

1) - Preparation of pentamethvl-1.2.2.6.6 pjpéridinvle-4 methacrylate:

0.93 g (0.038 mole) of magnesium are introduced into a 500 cm ³ pentacol reactor fitted with a central mechanical agitation, a thermometer and a thermally insulated distillation column 45 cm high. The reactor overhead is purged with nitrogen, then 15 g of anhydrous methanol are introduced.

The reaction medium is brought to 45 ° C. Hydrogen and magnesium dimethoxylate are formed. Once the evolution of hydrogen is completed, we add:

- 69.2 g (0.404 mole) of 4-hydroxy-pentamethyl-1, 2,2,6,6 piperidine (97% pure by mass), then

- 217 g (2J7 moles) of methyl methacrylate (99.8% pure by mass),

- 2J7 g of bis (3,5-ditertiobutyl 4-hydroxyphenyl) methane and the reaction medium is brought to its reflux temperature. The methanol formed distills for about two hours. The heating is then cut off; when the temperature has dropped to 40 ° C., 5 cm ³ of distilled water are poured with stirring.

A precipitate is formed which is fittrated, then the organic phase is dried over anhydrous sodium sulfate. Filtered again, then the medium is concentrated by evaporation of methyl methacrylate on a rotary evaporator (80 ° C under 7.98.10 Pa). From this concentrated medium, 56.7 g (0.233 mole) of 1,2-pentamethyl methacrylate are extracted by distillation under reduced pressure (75 ° C. under 0J J 0 ² Pa) in a vigorous column 45 cm high, 2,6,6 piperidinyl-4 98% pure (mass).

2) - Preparation of a mixed organopolysiloxane

In a 50 cm ³ tetracol reactor fitted with a central mechanical stirring, a thermometer and a ball cooler, the following are introduced: - 6.9 g of dry toluene,

- 0.0034 g of sodium acetate,

2.2 mg of the Karstedt catalyst solution described in Example 1, and

- 0.05 g of bis (3,5-ditertiobutyl 4-hydroxyphenyl) methane

The contents of the reactor are brought to 108 ° C. and the overhead of the reactor is inerted with nitrogen. It is then poured simultaneously in 80 minutes and using two separate syringes:

* Firstly :

- 98 g (0.062 mol) of pentamethyl methacrylate -1, 2,2,6,6 piperidinyl-4 pure at 98% resulting from example 4, (part 1), - 15 g of dry toluene,

_* and on the other hand:

- 5.2 g (0.082 mole of Si-H functions) of the polymethylhydrogenosiloxane oil used in Example 1.

2.2 mg of the Karstedt catalyst solution described in Example 1 are added twice during the reaction (2 hours, then 3 hours 30 minutes after the start of the reaction).

24 hours after the start of the reaction, the degree of transformation of the hydrogenosilyl functions (into moles) is 71% (ie a degree of transformation of the pentamethyl piperidinyl methacrylate functions of 93%); 8 g (0.0474 mole) of 95% by weight dodecene-1 are then injected in 20 minutes while maintaining the temperature at 108 ° O 4 hours after the end of the injection of dodecene, the rate of transformation of the hydrogenosilyl functions is 98.2%. The product obtained is then devolatilized for 2 hours 30 minutes at 130 ° C under a reduced pressure of 2.66.10 ² Pa. 21.8 g of a clear yellow oil are recovered, the characteristics of which are as follows: - Mn = 14110 g ;

- 271.4 meq of Z amino functions per 100 g of oil;

- average oil structure:

more nuclear magnetic resonance reveals the presence of 15 mol% of T units; proportion of Z functions: 73.5% (in moles of functions per 100 Si atoms); proportion of W functions: 20.8%.

Example 5

Preparation of a mixed oroanopolvsiloxane with a carboxylate ball joint

In a 50 cm ³ tetracol reactor fitted with a central mechanical stirring, a thermometer and a ball cooler, the following are introduced: - 31.1 g of dry toluene,

- 0.0034 g of sodium acetate, and

- 2.2 mg of the Karstedt catalyst solution described in Example 1.

The contents of the reactor are brought to 110 ° C. and the sky is inerted with nitrogen.

It is then poured simultaneously in 80 minutes and using two separate syringes: * on the one hand:

- 98 g (0.062 mol) of pentamethyl methacrylate -1, 2,2,6,6 piperidinyl-4 pure at 98% resulting from example 4, part 1), - 15 g of dry toluene, - 0.05 g of bis (3,5-ditertiobutyl 4-hydroxyphenyl) methane,

• And on the other hand :

- 9.74 g (0J54 mole of Si-H functions) of the polymethylhydrogenosiloxane oil used in Example 1. At the end of the flows, the conversion rate of the hydrogenosilyl functions is

20.4%. 2.2 mg of the Karstedt catalyst solution described in Example 1 are added twice during the reaction (3 hours, then 7 hours after the start of the reaction).

24 hours 30 minutes after the start of the reaction, the degree of transformation of the hydrogenosilyl functions (in moles) is 27% (ie a degree of transformation of the pentamethyl piperidinyl methacrylate functions of 68%); we then inject:

2.2 mg of the Karstedt catalyst solution described in Example 1 and

- 31 J g (0J84 mole) of dodecene-1 at 95% by weight in 20 minutes while maintaining the temperature at 110 ° C. 5 hours 30 minutes after the end of the injection of the dodecene, the rate of transformation of the hydrogenosilyl functions is 94.4%.

The product obtained is then devolatilized for 2 hours 30 minutes at 140 ° C under a reduced pressure of 2.66.10 ² Pa. 35.3 g of a clear yellow oil are recovered, the characteristics of which are as follows: • Mn = 12000 g

• 106.2 meq of Z amino functions per 100 g of oil

• average oil structure:

CH, CH, CH,

I I

<CH ,. , SiO Si-O- -Si -Si-O '-Si (CH ₃ ) ₃

I

. Ç ^H - 'J 12.7 C. I ₂ ..H " ₂ - ,, 5 -J 34.5 l_ ^H _I 2.8

more nuclear magnetic resonance reveals the presence of 3.4 mol% of T units; proportion of Z functions: 24.4% (in moles of functions per 100 atoms of Si); proportion of W functions: 66.3%. Example 6

Photostabilization of polvoropylene (PP)

Preparation of the compositions:

- mixing for 3 minutes at 160 ° C of 100 parts by weight of PP ELTEX® PHV001 P (grade 10) + 0.2 part of a commercial antioxidant (see definition below) +

0J part of calcium stearate + 0.2 part of stabilizer;

- compression under a plate press at 190 ° C (1 minute of contacting + 1 minute of holding at 250.10 ^ Pa + 1 minute of cooling at the same pressure).

One thus obtains quasi-circular plates of 200 micrometers thickness from which one cuts out test pieces.

Control composition: stabilizer = CHIMASORB 944 (cf. formula below) containing 341 meq of piperidinyl functions per 100 g of stabilizer.

Compositions b, c, d and e: stabilizers = silicone oils described respectively in examples 1, 3 (part 2), 4 (part 2) and 5.

Definition of the commercial antioxidant used: mixture 50/50 by weight of tetrakis (hydroxy-4'-ditertiobutyl-3 ', 5'-phenyl) -3 pentaerythrityl propionate (marketed under the name IRGANOX® 1010) and tris (ditertiobutyl-2,4-phenyOphosphite (marketed under the name IRGAFOS® 168).

CHIMASORB® 944 formula

The compositions b and c are tested under UV B, the compositions d and e under UV A. The control composition a is tested under UV A and UV B to serve as comparison. Under UV B, degradation is monitored by Infra-Red spectrometry. We measure every two days, until the film breaks, the increase in absorbance (in abbreviation A2) of the carbonyl band at 1720 cm ^-1 resulting from the degradation of the PP and we reduce this absorbance absorbance (abbreviation A1) of a band of an inert group (methylene at 2722 cm'1).

A2 / A1 after: Concentration of amino functions

(meq / 100 g of oil)

Composition 2 days 4 days 6 days 8 days 9 days a 0.054 0.066 0.13 break 341 b 0.075 0.076 0.07 0.08 break 197.8 c 0.058 0.046 0.08 0.09 break 248.3

Under UV At the degradation being much slower than under UV B, the stabilization test is carried out by simply comparing the durations at the end of which there is rupture of the test specimens (D). For each composition, three test pieces are tested.

Claims

1.- Mixed polyorganosiloxane, characterized in that it comprises per molecule at least 3 siloxy units, of which: - at least one functional siloxyl unit of formula:

(D

in which :

• the symbol X represents a monovalent group of formula -A-Z where:

• A is a divalent radical chosen from an oxygen atom and a radical of formula -CH2-CHR ² -COO- with R ² being a hydrogen atom or a linear or branched alkyl radical having from 1 to 3 atoms carbon, the free valence carried by the carbon atom being linked to the silicon atom;

• the symbol Z represents a monovalent group, whose free valence is carried by a carbon atom, comprising a secondary or tertiary amine function, included in a cyclic hydrocarbon chain comprising from 8 to 30 carbon atoms, in which the two atoms cyclic carbon located in the α and a positions with respect to the cyclic nitrogen atom do not contain a hydrogen atom;

• a is a number chosen from 0, 1 and 2; and

- at least one other functional siloxyl unit of formula:

(R *) _b WSi (O) _{3 b} (H)

in which :

• the symbols R ¹ have the same meanings as those given above with regard to formula (I); • the symbol W represents a monovalent group with a compatibilizing function chosen from: an alkyl radical, linear or branched, having more than 10 carbon atoms; a radical of formula -R ³ -COO-R ⁴ in which R ³ represents an alkylene radical, linear or branched, having from 5 to 20 carbon atoms and R ⁴ represents an alkyl radical, linear or branched, having from 1 to 12 carbon atoms; a radical of formula -R5-O- (R6-O) _c -R ⁷ in which R ^ represents an alkylene radical, linear or branched, having 3 to 15 carbon atoms, R ⁶ represents an alkylene radical, linear or branched, having 1 to 3 carbon atoms, c is a number from 0 to 10 and P represents a hydrogen atom, a radical alkyl, linear or branched having from 1 to 12 carbon atoms or an acyl radical -CO-R ³ where R ³ represents a linear or branched alkyl radical having from 1 to 11 carbon atoms;

• b is a number chosen from 0, 1 and 2.

2. Polyorganosiloxane according to claim 1, characterized in that it also comprises at least one other siloxyl unit of formula:

⁽ rf ⁾ . (H) If (O) (III)

4- (d + e)

in which :

• d is a number chosen from 0, 1, 2 and 3;

• e is a number chosen from 0 and 1;

• the sum d + e is at most equal to 3.

3.- Polyorganosiloxane according to claim 1 or 2, characterized in that the radicals R ¹ are: methyl, ethyl, n-propyl, isopropyl, n-butyl, and the carboxylate patella is chosen from divalent radicals -CH2-CH2- COO- and -CH2-CH (CH3) - COO-.

4. Polyorganosiloxane according to any one of claims 1 to 3, characterized in that the amino functions Z are chosen from amine functions, secondary or tertiary, included in a cyclic hydrocarbon chain, of formula:

in which :

The radicals R®, identical or different from each other, are chosen from alkyl radicals, linear or branched, having from 1 to 3 carbon atoms, phenyl and benzyl, . R10 _is chosen from a hydrogen atom, alkyl radicals, linear or branched, having from 1 to 12 carbon atoms, alkylcarbonyl radicals in which the alkyl residue is a linear or branched residue having from 1 to 8 carbon atoms, phenyl and benzyl radicals and an O- radical; • h is a number chosen from 0 and 1.

5. Polyorganosiloxane according to any one of claims 1 to 4, characterized in that the compatibilizing functions W are chosen: from an alkyl radical, linear or branched, having from 11 to 30 carbon atoms; a radical of formula - R ³ -COO-R ⁴ in which R ³ represents an alkylene radical, linear or branched, having from 8 to 12 carbon atoms and R ⁴ represents an alkyl radical, linear or branched, having from 1 to 6 carbon atoms; a radical of formula -R ⁵ -O- (R ⁶ -O) _c -R ⁷ in which R ⁵ represents an alkylene radical, linear or branched, having 9 to 12 carbon atoms, R ⁶ represents a linear alkylene radical or branched having from 2 to 3 carbon atoms, c is a number from 0 to 6 and R ⁷ represents a hydrogen atom, an alkyl radical, linear or branched, having from 1 to 6 carbon atoms or an acyl radical -CO -R ³ where R ³ represents an alkyl radical, linear or branched, having from 1 to 3 carbon atoms.

6. Polyorganosiloxane according to any one of claims 1 to 5, characterized in that it is chosen from:

in which :

• the symbols R ¹ , X and W have the general meanings given above with regard to formulas (I) and (II); • the symbols Y represent a monovalent radical chosen from R ¹ , X, W and a hydrogen atom;

• m is a whole or fractional number ranging from 0 to 180;

• n is a whole or fractional number ranging from 0 to 180;

• p is a whole or fractional number ranging from 0 to 10; • q is a whole or fractional number ranging from 0 to 100; with the conditions under which:

- if m = 0 and n is different from 0: at least one of the substituents Y represents the radical X; the sum m + n + p + q is in the range from 5 to 100; and the ratio 100 n / m + n + p + q + 2 - 0.5;

• if m is different from 0 and n = 0: at least one of the substituents Y represents the radical W; the sum m + n + p + q is in the range from 5 to 100; and the ratio 100 m / m + n + p + q + 2 ≥ 0.5; and

and those of medium formula

in which :

• the symbols R ¹ , X and W have the general meanings given above with regard to formulas (I) and (II); r is a whole or fractional number ranging from 1 to 9; s is a whole or fractional number ranging from 1 to 9; t is an integer or fraction ranging from 0 to 0.5; u is a whole or fractional number ranging from 0 to 5; the sum r + s + t + u is in the range from 3 to 10.

7.- Polyorganosiloxane PL1 according to claim 6, characterized in that:

• the symbols Y represent R ¹ ; • m is a whole or fractional number ranging from 1 to 90;

• n is a whole or fractional number ranging from 1 to 90

• p is a whole or fractional number ranging from 0 to 5;

• q is a whole or fractional number ranging from 0 to 50;

• the sum m + n + p + q is a whole or fractional number ranging from 10 to 100; • the 100 m / + n + p + q + 2 ratio is in the range from 10 to 90; • the ratio 100 n / m + n + p + q + 2 is in the range from 10 to 90, this ratio being identical or different from the previous report;

• the radicals R ¹ , X and W have simultaneously the definitions given above with respect to each of them in claims 3, 4 and 5.

8.- PC1 polyorganosiloxane according to claim 6, characterized in that: r is an integer or fractional number ranging from 1 to 4.5; s is a whole or fractional number ranging from 1 to 4.5; t is an integer or fraction ranging from 0 to 0.25; • u is a whole or fractional number ranging from 0 to 2.5; the sum r + s + 1 + u is a whole or fractional number ranging from 3 to 5; the radicals R ¹ , X and W have simultaneously the definitions given above with respect to each of them in claims 3, 4 and 5.

9.- Process for the preparation of a mixed polyorganosiloxane with an oxygen ball, according to any one of Claims 1 to 8, characterized in that, according to said process, it is obtained by simultaneous dehydrogenocondensation and addition (hydrosilylation) reaction or by successive dehydrogenocondensation and addition (hydrosilylation) reactions, starting from: corresponding organohydrogenopolysiloxanes (H) free from the Z functions equipped with the oxygen patella and W, from the organic compound (s) ( s) hydroxylated (Ψ) from which derives (s) the Z function (s) equipped with the oxygen patella, and the ethylenically unsaturated compound (s) at the end of chain (Ξ) from which derives the function (s) W, and that the quantities of reagents used correspond to a molar ratio [(Ψ) + (Ξ)] / SiH [of (H )] which is in the range of 1 to 5.

10.- A process for preparing a mixed polyorganosiloxane with a carboxylate ball joint, according to any one of claims 1 to 8, characterized in that, according to said process, it is obtained by reaction of simultaneous or successive additions (hydrosilylations), this from: corresponding organohydrogenpolysilanes (H) free from the Z functions equipped with the carboxylate patella and W, from the ethylenically unsaturated organic compound (s) at the end of the chain (Ψ ' ) from which derives the Z function (s) equipped with the carboxylate patella, and the ethylenically unsaturated compound (s) at the end of the chain (Ξ) from which derives ( nt) the function (s) W, and that the quantities of reagents used correspond to a molar ratio [(Ψ ') + (Ξ)] / SiH [of (H)] which is order from 1 to 5.

11.- Method according to claim 9, characterized in that the hydroxylated organic compounds (Ψ), from which the Z functions equipped with the oxygen ball joint are derived (or also: from which the monovalent groups X are derived), are those of formula:

in which the symbols Pβ, R ¹ ^ and h have the meanings given above with regard to formula (IV).

12.- Method according to claim 10, characterized in that the unsaturated organic compounds (Ψ ') from which the Z functions equipped with the ball joint are derived (or also: from which the monovalent groups X are derived), are those of formula:

in which the symbols R ² , R®, R ^" O and h have the meanings given above with regard to the definition of the symbol X and of the formula (IV).

13.- Use of an effective amount of a mixed polyorganosiloxane according to any one of claims 1 to 8, as stabilizers against the light, oxidative and thermal degradation of organic polymers.

14.- Use according to claim 13, characterized in that the organic polymers to be stabilized are chosen from polyolefins, polyurethanes, polyamides, polyesters, polycarbonates, polysulfones, polyethersulfones, polyether ketones, acrylic polymers, their copolymers and their blends.

15.- Composition of organic polymer stabilized against light, oxidizing and thermal degradation, characterized in that it comprises:

- per 100 g of organic polymer to be stabilized,

- An amount of mixed polyorganosiloxane according to any one of claims 1 to 8 which provides from 0.04 to 20 milliequivalents depending on the sterically hindered amine function (s).

16.- Composition according to claim 15, characterized in that the organic polymers to be stabilized are chosen from polyolefins, polyurethanes, polyamides, polyesters, polycarbonates, polysulfones, polyether sulfones, polyether ketones, acrylic polymers, their copolymers and their blends.