WO2010009755A1

WO2010009755A1 - Curable silicone compositions comprising aryl-phosphites

Info

Publication number: WO2010009755A1
Application number: PCT/EP2008/059525
Authority: WO
Inventors: Helmut Steinberger; Bogdan Marciniec; Ireneusz Kownacki
Original assignee: Momentive Performance Materials Gmbh
Priority date: 2008-07-21
Filing date: 2008-07-21
Publication date: 2010-01-28

Abstract

The present invention relates to hydrosilylation-curing polyorganosiloxane compositions and/or silane compositions comprising phosphites, transition metal compounds comprising phosphite ligands, cured products prepared from the hydrosilylation-curing polyorganosiloxane compositions and/or silane compositions and new phosphites.

Description

CURABLE SILICONE COMPOSITIONS COMPRISING ARYL- PHOSPHITES

The present invention relates to hydrosilylation-curing polyorganosiloxane compo- sitions and/or silane compositions comprising phosphites, transition metal compounds comprising phosphite ligands, cured products prepared from the hydrosilylation-curing polyorganosiloxane compositions and/or silane compositions and new phosphites. In particular, the invention is related to transition metal compounds comprising polycycloaliphatic phosphites and the use of those phosphites as inhibit- tors in hydrosilylation curing silicone compositions.

Platinum-(0)-vinylsiloxane complexes such as the divinyltetramethyl-disiloxane complex (Karstedt's catalyst) or tetravinyltetramethyl-cyclotetrasiloxane can catalyse the hydrosilylation reaction at very high reaction rates. Therefore these catalysts are currently used for crosslinking, curing or vulcanization of silicone rubber having alkenyl and SiH-groups by hydrosilylation between 20-200 ⁰C. However, this reaction at room temperature according to Arrhenius Law sometimes shortens the pot-life or bath-life time in an unacceptable manner (1 -10 min at 25 ⁰C).

It is well known from prior art disclosures that the high reaction rates of platinum catalysts can be slowed down by inhibitors, such as esters, e.g. maleates and fumarates, ketones, sulfoxides, phosphines, phosphites, nitrogen- or sulphur containing derivatives, hydroperoxides as well as acetylene derivatives such as alkinoles. If one describes the effect of such inhibitors in terms of Arrhenius Law one can observe in generally a shifted line in a diagram showing 1/k (k=reaction constant [s ¹] ) over 1/T (⁰K) as x-axis, i.e. if the pot-life is extended one can observe at the same time a decreased reaction rate at higher temperatures.

Some prior art documents attempt to decouple the effect of pot-life and cure rate at higher temperature. For example US 3,188,300 discloses specific aliphatic, cyclo- aliphatic and aromatic phosphites in order to anticipate premature gelling at 20 - 30 ⁰C. EP 948565 A1 discloses siloxane compositions comprising substituted and aromatic phosphites which shows a different relation between cure rate at 140 ⁰C and pot-life at room temperature. US 2006/0135689 (Fehn) discloses siloxane compositions comprising olefin-nitrogen containing-ligand-platinum complexes, which should have enlarged pot-life at room temperature and high reaction rates at higher temperatures.

US 2006/0128881 A1 and US 2004/0116561 A1 disclose hydrosilylation curing polyorganosiloxane compositions comprising phosphites but fail to disclose phosphites having aryloxy groups substituted by further alkenyl and/or aryl groups. Moreover these documents are not concerned with the technical object of decouple the effect of pot-life and cure rate at higher temperature in hydrosilylation curing polyorganosiloxane compositions.

US 3,188,300 A1 and US 5,380,812 also disclose the use of phosphite inhibitors as inhibitors in hydrosilylation curing silicone compositions. Among the possible substituents there are also mentioned monocycloaliphatic groups, i.e. cyclohexyl and trisphenylphosphite. The present inventors have found however, that the use of tris(cyclohexyl)-phosphite or tris(phenyl)-phosphite reveals an unacceptable low curing rate at high temperatures, although the pot-life or storage stability, respectively, is acceptable. The disclosed aromatic phosphites of prior art have high melting points. Therefore there is also a need to improve the homogenous distribution or miscibility of the phosphites in the silicone compositions.

Therefore, the present invention attempts to provide hydrosilylation curing polyorganosiloxane compositions, in particular, ^'one-part^' hydrosilylation curing polyorganosiloxane compositions that have a high pot-life, i.e. storage stability, and at the same time have high curing rates at high temperatures, which property is not affected upon long-term storage. The present inventors have found that surprisingly phosphites having substituted aromatic groups with specific residues are suitable to solve these problems and can provide better dispersibility due to lower melting points. Accordingly the present invention is related to hydrosilylation-curing polyorganosiloxane compositions and/or silane compositions, comprising one or more phosphites having the formula:

P(OR)₃ (I)

wherein

Embodiment (I):

R is an aromatic group (in the following sometimes referred to as to the first aromatic group), substituted by at least one, preferably one to three, aromatic groups (in the following sometimes referred to as to the second aromatic group), or

Embodiment (II):

R is an aromatic group substituted by at least one, preferably one to three, alkenyl groups. In this case, the aromatic group is not substituted by an aromatic group, so the two cases are distinct.

The substitutents R to R which can be identical or different are selected from the group which consists of hydrogen and substituents defined for the embodiments (I) or (II), wherein at least one group R³, R⁴, R⁵ and R⁶ is not hydrogen:

Embodiment (I): In the preferred embodiment the aromatic groups (including first and second aromatic group) in the definition of formula (I) are all phenyl groups.

The first aromatic group R may have apart from the second aromatic group(s) one to three further substituent groups, which may include saturated or unsaturated hydrocarbyl groups, like alkyl, in particular methyl, ethyl and tert. -butyl, or alkenyl, in particular vinyl and allyl, each hydrocarbyl group having preferably up to 6 carbon atoms; alkoxy having preferably up to 6 carbon atoms, in particular methoxy, ethoxy and tert.-butoxy; alkenyloxy having preferably up to 6 carbon atoms, in particular allyloxy.

The second aromatic group(s) (R³; R⁴, R⁵ and R⁶) may have one to three substituent groups, which may include saturated or unsaturated hydrocarbyl groups, like alkyl, in particular methyl, ethyl and tert. -butyl, or alkenyl, in particular vinyl and allyl, each hydrocarbyl group having preferably up to 6 carbon atoms; alkoxy having preferably up to 6 carbon atoms, in particular methoxy, ethoxy and tert.-butoxy; alkenyloxy having preferably up to 6 carbon atoms, in particular allyloxy.

In a preferred embodiment R is phenyl substituted by one to three phenyl groups. Particularly R is phenyl substituted by one phenyl group in the 2-, 3- or 4-position, preferably in the 2-position (ortho).

Examples of the phosphites of the formula (I) are selected from the group consisting of:

Tris(2,6-diphenyl)phenyl phosphite:

Tris(2,4-diphenyl)phenyl phosphite, Tris(2,4,6-triphenyl)phenyl phosphite, Tris(2,5-diphenyl)phenyl phosphite, Tris(3,5-diphenyl)phenyl phosphite, Tris(2-phenyl)phenyl phosphite:

Tris(3-phenyl)phenyl phosphite,

Tris(4-phenyl)phenyl phosphite,

Embodiment (II):

In the embodiment (II) R is an aromatic group substituted by at least one, preferably one to three, alkenyl groups. In this case, the aromatic group is not substituted by an aromatic group, so the two cases are distinct.

The aromatic group R in this embodiment is preferably a phenyl group.

The alkenyl group in this embodiment is preferably a vinyl or an allyl group.

Apart from the alkenyl group the aromatic group may have one to three further substituent groups (R³; R⁴, R⁵ and R⁶), which may include hydrocarbyl groups, like alkyl, in particular methyl, ethyl and tert.-butyl, each hydrocarbyl group having preferably up to 6 carbon atoms; alkoxy having preferably up to 6 carbon atoms, in particular methoxy, ethoxy and tert.-butoxy; alkenyloxy having preferably up to 6 carbon atoms, in particular allyloxy. Preferably R in the embodiment (II) is phenyl substituted by one or more alkenyl groups, preferably allyl or allyloxy groups.

Most preferred R is a phenyl group substituted by one allyl group:

in particular:

The inhibiting activity of the phosphites used in accordance with the present invention in the transition metal catalyzed hydrosilylation reaction is a consequence of the complex formation of the phosphites and the transition metal compound. Thus the present invention in a further aspect is also related to transition metal compounds, comprising at least one of the phosphites according to the invention. The transition metal in such transition metal compounds is preferably selected from group consisting of nickel, ruthenium, rhodium, palladium, osmium, iridium, and platinum, with platinum being the most preferred transition metal compound. Although it is possible to isolate transition metal compounds having those specific phosphite ligands of the invention, in the practice of hydrosilylation curing polyorganosiloxane systems, in general, certain common transition metal compounds are added together with the phosphites to the polyorganosiloxanes without separate formation of the transition metal phosphite complex compounds, or alternatively certain transition metal compounds are reacted with the phosphites so to say in situ, the reaction product being added to the hydrosilylation curing polyorganosiloxane systems. So from a technical point of view the isolation of the transition metal phosphite complex compounds has normally no importance and it suffices to determine the influence of the addition of the phosphites on the pot-life or storage stability and the curing rates at higher temperatures without identifying exactly the catalytical active transition metal species. Nevertheless one can prepare and isolate on the other hand the underlying transition metal compounds of the phosphites of the invention by commonly known ligand exchange reactions. For example the well-known Karstedt catalyst can be reacted with the phosphites of the present invention to give the transition metal compounds in accordance with the present invention: The synthesis follows a pathway in that by example the well-known divinyl-tetramethyldisiloxane (^'DVTMDS^') -bridged binuclear platinum complex (Karstedt's catalyst) can be cleaved by any nucleophile (e.g. phosphite), giving a mononuclear platinum complexes:

In another aspect of the present invention it relates to the use of one or more phosphites according to the invention for the manufacture of hydrosilylation-cuhng polyorganosiloxane and/or silane compositions, and in particular the use of one or more as inhibitors of the hydrosilylation reaction in the curing of polyorganosiloxane compositions and/or silane compositions. Furthermore the invention relates to hydrosilylation-curing polyorganosiloxane compositions and/or silane compositions, comprising at least one or more of the phosphites according to the invention, the preferred ones given above.

The invention moreover relates to hydrosilylation-curing polyorganosiloxane compositions and/or silane compositions, comprising:

(A) one or more polyorganosiloxanes and/or silanes having in average at least two alkenyl groups, (B) one or more polyorganosiloxanes and/or silanes having in average at least two SiH groups,

(C) one or more transition metal compounds, wherein the transition metal is selected from group consisting of nickel, ruthenium, rhodium, palladium, osmium, iridium, and platinum,

(D) one or more of the phosphites as defined in formula (I), and

(E) optionally one or more auxiliary agents.

Component (A)

The inventive composition comprises one or more polyorganosiloxanes and/or silanes having in average at least two alkenyl groups (A) e.g. those disclosed in US 3,096,303, US 5,500,148 A (examples). Suitable compounds (A) can be described by the general formula (III),

[M_aD_bTcQd]m (III)

wherein the formula (III) represents the ratios of the siloxy units M₁D₁T and Q, which can be distributed blockwise or randomly in the polymer chain. Within a polysiloxane chain each siloxane unit can be identical or different and preferably

a = 1 -10 b = 0 -12000 c = 0 - 50 d = 0 - 1 m = 1 - 5000. These indices should represent the average polymerisation degree P_n based on the average number molecular mass M_n.

The polymer (A) is preferably selected from the group of alkenyl-containing polyorganosiloxanes, which can undergo hydrosilylation reactions with hydrogen siloxanes to form silicon carbon bonds.

The polymer (A) or mixtures thereof comprise groups selected from

T= RSiO₃Z₂, or T^*

Q=SiO_4/2, divalent R²-groups, wherein M^*= R¹pR_3-pSiOi/2, D^*= R¹ _qR2-qSiO₂/2, T^*= R¹SiO₃Z₂, wherein p= 1 -3, q= 1 -2.

R is preferably selected from n-, iso, or tertiary CrC3o-alkyl, alkoxyalkyl, C₅-C₃O- cyclic alkyl, or C₆-C₃o-aryl, alkylaryl, which groups can be substituted by one or more O-, N-, S- or F-atom, e.g. ethers or amides or PoIy(C₂ -C₄)-alkylene ethers with up to 1000 alkylene oxy units.

Examples of said monovalent residues R in component (A) include hydrocarbon groups and halohydrocarbon groups.

Examples of suitable monovalent hydrocarbon radicals include alkyl radicals, preferably such as CH₃-, CH₃CH₂-, (CH₃)₂CH-, C₈H₁₇- and Ci₀H₂₁-, cycloaliphatic radicals, such as cyclohexylethyl, aryl radicals, such as phenyl, tolyl, xylyl, aralkyl radicals, such as benzyl and 2-phenylethyl. Preferable monovalent halohydrocarbon radicals have the formula C_nF_2n+iCH₂CH₂- wherein n has a value of from 1 to 10, such as, for example, CF₃CH₂CH₂-, C₄F₉CH₂CH₂-, C₆F₁₃CH₂CH₂-, C₂F₅-O(CF₂-CF₂-O)_1-10CF₂-, F[CF(CF₃) -CF₂-O]_1-5- (CF₂)_0-2- C₃F₇-OCF(CF₃)- and C₃F₇-OCF(CF₃) -CF₂-OCF(CF₃)-.

Preferred groups for R are methyl, phenyl, 3,3,3-trifluoropropyl.

R¹ is selected from unsaturated groups, comprising C=C-group-containing groups (alkenyl groups), e.g.: n-, iso-, tertiary- or cyclic- C₂-C₃o-alkenyl, C₆-C₃o-cycloalkenyl, Cs-C_3O -alkenylaryl, cycloalkenylalkyl, vinyl, allyl, methallyl, 3-butenyl, 5-hexenyl, 7- octenyl, ethyliden-norbornyl, styryl, vinylphenylethyl, norbornenyl-ethyl, limonenyl, substituted by one or more O- or F-atoms, e.g. ethers, amides or C₂-C₄-polyethers with up to 1000 polyether units. The alkenyl radicals are preferable attached to terminal silicon atoms, the olefin function is at the end of the alkenyl group of the higher alkenyl radicals, because of the more ready availability of the alpha-, omega- dienes used to prepare the alkenylsiloxanes.

Preferred groups for R¹ are vinyl, 5-hexenyl.

R² includes for example divalent aliphatic or aromatic n-, iso-, tertiary- or cyclo- CrC₁₄-alkylene, arylene or alkylenearyl groups which brigde siloxy units. Their content does not exceed 30 mol.% of all siloxy units. Preferred examples of suitable divalent hydrocarbon groups R² include any alkylene residue, preferably such as -CH₂-, -CH₂CH₂-, -CH₂(CH₃)CH-, -(CHz)₄-, -CH₂CH(CH₃)CH₂-, -(CHz)₆-, -(CHz)₈- and -(CH₂)₁₈-; cycloalkylene radical, such as cyclohexylene; arylene radicals, such as phenylene, xylene and combinations of hydrocarbon radicals, such as benzylene, i.e. -CH₂CH₂-CeH₄-CH₂CH₂-, -CeH₄CH₂-. Preferred groups are alpha, omega- ethylene, alpha, omega-hexylene or 1 ,4-phenylene.

Examples of suitable divalent halohydrocarbon radicals R² include any divalent hydrocarbon group wherein one or more hydrogen atoms have been replaced by halogen, such as fluorine, chlorine or bromine. Preferable divalent halohydrocarbon residues have the formula -CH₂CH₂(CF₂)_1-10CH₂CH₂- such as for example, -CH₂CH₂CF₂CF₂CH₂CH₂- or other examples of suitable divalent hydrocarbon ether radicals and halohydrocarbon ether radicals including -CH₂CH₂OCH₂CH₂-, -CeH₄-O- C₆H₄-, -CH₂CH₂CF₂OCF₂CH₂CH₂-,and -CH₂CH₂OCH₂CH₂CH₂-.

Such polymers containing R, R¹ and/or R² radicals are polyorganosiloxanes, e.g. alkenyl-dimethylsiloxy or trimethylsiloxy terminated polydimethylsiloxanes, which can contain other siloxane units than alkenylmethylsiloxy groups dimethylsiloxy groups such as poly-(dimethyl-co-diphenyl)siloxanes.

Broadly stated component (A) of the compositions of this invention can be any polyorganosilicone compound containing two or more silicon atoms linked by oxygen and/or divalent groups R² wherein the silicon is bonded to 0 to 3 monovalent groups per silicon atom, with the proviso that the organosilicon compound contains at least two silicon-bonded unsaturated hydrocarbon residues. This component can be a solid or a liquid, free flowing or gum-like i.e. it has measurable viscosity of less than 100 kPa.s at a shear rate of D=1 s^"1 at 25 ⁰C.

The siloxane units with radicals R and/or R¹ can be equal or different for each silicon atom. In a preferred version the structure is represented by the general formulas (Ilia) to (MIb), shown below. One preferred polyorganosiloxane component (A) for the composition of this invention is a substantially linear polyorganosiloxane (A) having the formula (Ilia) or (MIe) to (MIi). The expression "substantially linear" includes polyorganosiloxanes that contain not more than 0.2 mol.% (trace amounts) of siloxy units of the type T or Q. This means the polymer (A) is preferably a linear, flowable fluid or gum (A1 ) with a Newton like viscosity but not solid at 25 ⁰C.

R¹pR3-pSiO(R₂SiO)bSiR₃-pRp¹ (MIa) (A1 )

R¹ _PR₃-p (R2SiO)bi(R¹qR₂-_q SiO)bix SiRs-pRp¹ (MIb) b = > 0 - 12000 b1 = > 0 -12000 b1x = 0 -1000 b1 + b1x = > 0 - 12000 p= 0 to 3 q= 1 to 2,

with the proviso, that there are at least two alkenyl groups per molecule.

Preferred groups for R are methyl, phenyl, 3,3,3-trifluoropropyl Preferred groups for R¹ are vinyl, hex-5-enyl and cyclohexenyl-2-ethyl

The average polymerization degrees Pn or ^'b^' etc. is based on M_n as average number mol mass in the range of up to 12000, the preferred range is 500 to 5000. The viscosity of such polymers is in the range of 10 to 100,000,000 mPa.s at 25 C at a shear rate of D=1 s^"1, the preferred range is about 200 to 10,000,000 mPa.s. Such a viscosity at 25 C for the component (A) is suitable for the application of the manufacturing of broad variety of products such as molded or extruded shaped rubber parts with liquid silicone rubbers and high viscous rubbers, curable ^'Formed- in-Place^'- sealants well as coatings of substrates.

In the group of alkenyl comprising siloxanes (A) the addition of other so-called vinyl rich polymers (A2) is preferred in order to modify mechanical properties.

The polymers (A2) are selected either from the group consisting of polymers of the formulas (1Mb) to (MId) or (NIh) to (MIi), i.e. linear polyorganosiloxanes having additional alkenyl side groups or branched polyorganosiloxanes having a higher concentration of T- and Q-groups than the previous types.

Me3SiO(Me2SiO)bi(MeViSiO)biχSiMe₃ (MIc) ,and

ViMe₂SiO(Me₂SiO)_bi(MeViSiO)_biχSiMe₂Vi (MId), whereby

Vi= vinyl. Th e preferred value of b1x is less than 0.5 ^* b1 or zero. If b1x is not zero then it is preferably between 0.0003^*b1 to 0.25^*b1 preferably 0.0015^*b1 to 0.15^*b1.

Other preferred structures according of the formulas (MIe) to (MIi) achieve suitable viscosities as defined lateron and describe polymers applicable without any solvent for a viscosity adjustment. The range of subindices defines a range of the possible average polymerization degrees P_n.

Vi_PMe_3-PSiO(Me₂SiO)_Io_-I2OOo SiMe_3-PVi_P (III e) PhMeViSiO(Me₂SiO)io-i₂ooo SiPhMeVi (MI f),

VipMe_3-pSiO(Me₂SiO)io-i₂ooo (MeViSiO)i_-25oo SiMe_3-p Vi_p (III g),

Me₃SiO(Me₂SiO)io-i₂ooo (MeViSiO)i_-25ooSiMe₃ (III h),

PhMeViSiO(Me₂SiO)_Io_-I2OOo (MePhSiO)_I-IOOoSiPhMeVi (III i) and wherein Ph= phenyl, p= 0 to 3, preferred p=1.

In a preferred embodiment the polymer component (A) is a mixture of polymers of the formula (Ilia) and of the formula (IHb) or (IHh) whereby (MIb) has an alkenyl content of 1 to 50 mol.% in a ratio in that the alkenyl content of mixture of (A1 ) and (A2) is below 2 mol.%.

Another class of preferred polymers are branched polyorganosiloxanes (A2) having a high concentration of SiMe_(3-P)(alkenyl)_p groups with distinct cure rates. Such structures are especially used in release coating applications. Branched polymers are dechbed e.g. in US 5,616,672 and are preferably selected from those of the formula(lll) wherein the polyorganosiloxane (A2) comprising alkenyl groups has more than 0.2 mol.% of T=RSiO₃/₂ or Q=S iO₄/₂-u nits.

Preferably the branched vinyl-rich polymers have a range of D : T > 10 : 1 preferably > 33 : 1 and/or respectively (M^alkenyl : Q) = 0.6 - 4 : 1.

All these polymers can be prepared by any of the conventional methods for pre- paring triorganosiloxane-terminated polydiorganosiloxanes. For example, a proper ratio of the appropriate hydrolyzable silanes, e.g., vinyldimethylchlorosilane and dimethyldichlorosilane, may be co-hydrolyzed and condensed or alternately an appropriate 1 ,3-divinyltetraorganodisiloxane, e.g., symmetrical divinyldimethyldi- phenylsiloxane or divinyltetramethylsiloxane, which furnishes the endgroups of the polydiorganosiloxane, may be equilibrated with an appropriate dipolyorganosilo- xane, e.g., octamethylcyclotetrasiloxane, in the presence of an acidic or basic catalyst. Regardless of the method of preparation of polydiorganosiloxane (A), there is usually coproduced a varying quantity of volatile, cyclic polydiorganosiloxanes.

The viscosities of the polydiorganosiloxanes (A) defined above for the purposes of this invention, refer preferably essentially free of cyclic polydiorganosiloxanes (less than 1 wt.%, preferably 0.5 wt.% measured for 1 h 150 ⁰C 20 mbar) portion of the polyorganosiloxane. This essentially cyclic free portion can be prepared by stripping the polydiorganosiloxane at 150 ⁰C for at least 1 hours to yield a polymer residue of this type. This residue will be essentially free of cyclic material with the exception of trace quantities of macrocyclic polydiorganosiloxanes (molecular weight > 518 g/mol) which are non-volatile as defined above.

The average polymerization degree P_n of the polymer (A) measured by GPC measurement versus polystyrene standard based on the average number mol weight M_n is preferably in the range of > 10 to 12000, the more preferred range is 40 to 6000. The viscosities of such polymers are in the range of 10 to 50,000,000 mPa.s at 25 ⁰C at a shear rate of D=1 s^"1 . The value for P_n or the index ^'b^' in the above formula (Ilia) is such that the linear polyorganosiloxane (A) has a viscosity at 25 ⁰C, of at least 10 mPa.s. Preferably the range of the viscosity is from about 40 mPa.s to 35,000,000 mPa.s and, most preferably from 100 mPa.s to 25,000,000 mPa.s. Said viscosity corresponds approximately to the values of the average P_n, indicated by ^' b^' or ^'b1 +b1x^'.

The concentration of the functional unsaturated groups are in the range of 50 mol.% to 0.033 mol.% (mol-% of functionalized Si-atoms per total of Si-atoms), i.e. in case of polydimethylsiloxanes about preferably 0.002 to 12 mmol /g, more preferred 0.004 - 3 mmol/g. Said siloxane units can be combined in any molecular arrangement such as linear, branched, cyclic and combinations thereof, to provide polyorganosiloxanes (A1 ) and (A2) that are useful as component (A). In a preferred embodiment the hydrosilylation-curable composition is solvent-less (less than 1 wt.-% volatiles).

The composition according to the invention is preferably used to coat a solid substrate, such as paper, fabrics or thermoplastic films with an adhesive-releasing layer or for extruding, calendering or molding shaped formed articles, laminates or for ^'Formed-ln-Place^'- sealing masses.

The alkenyl content of the components (A) can be determined here by way of ¹H NMR - see A.L. Smith (ed.): The Analytical Chemistry of Silicones, J. Wiley & Sons 1991 Vol. 112 pp. 356 et seq. in Chemical Analysis ed. by J. D. Winefordner.

The component (A) can be also selected of the group of silanes such as of the general formulae:

wherein R, R¹ is as defined above, R⁹ is as defined below, and e = 0 - 3 f = 1 - 4, and e + f = 4;

(R⁹O)₍3-g_-h)(R¹g)(R_h)Si-R²-Si(R_h)(R¹g)(OR⁹)_(3-h-g), (R⁹2N)(^.h)(R¹g)(Rh)Si-R²-Si(Rh)(R¹g)(NR⁹ ₂)(3-h-g),

wherein R, R¹ and R² is as defined above, R⁹ is as defined below, and

g = 1-3, h = 0-2, and g + h = 3.

Component (B) -(crossl inker)

The curable compositions of the invention use a crosslinker and/or chain extender component (B) for the polymers defined under (A). The component (B) is from the group consisting of silanes, siloxanes having at least 2 SiH groups, which can react with alkenyl groups of the polymers (A) and crosslink both polymers to an elastomeric network. In order to get a more elastomehc behaviour rather than a gel it is preferred that at least 30 mol.-% of the component (A) or (B) should have a functionality of reactive groups of 3 or more (number of Si-alkenyl groups per total of

Si atoms for (A) and number of SiH-groups per total of Si atoms for (B)).

The component (B) is preferably selected from the group of SiH-containing polyorganosiloxanes and SiH-containing organosilanes respectively hydrogen silyl modified hydrocarbons. Suitably component (B) is composed of siloxane units selected from the groups M= R₃SiOi/₂, M^H=RYSiOi_/2, D=R₂SiO₂Z₂, D^H=RYSiO_2/2, T=RSiO₃/₂, T^H=YSiO₃/₂, SiO_4/2, wherein R is as defined above and Y = R¹ and/or H, with the proviso that there are in average at least two SiH-groups per molecule.

For example, they include:

ReHfSi(OR )(4-e-f)

ReH_fSi(NR⁹ ₂)_(4-e-f) wherein R is as defined above, R⁹ is as defined below, and e = 0 - 3 f = 1 - 4, and e + f = 4.

Further (R⁹O)_(3-g-h)(H_g)(R_h)Si-R²-Si(R_h)(H_g)(OR⁹)₍3_-h-g)> (R⁹ ₂N)_(3-g-h)(H_g)(R_h)Si-R²-Si(R_h)(H_g)(NR⁹ ₂)₍3_-h-g)j wherein g, h, R, R², R⁹ is as defined above or below.

This means the polymer (B) can be formally described by the ratios of the general formula (II),

wherein the siloxy units M, D, T and Q are as defined above including the possible SiH-containing M, D, T groups. Also possible is that part of the siloxy groups are alkenyl siloxy groups, as long as there are at least in average two SiH-groups per molecule. The siloxy units can be distributed blockwise or randomly in the polymer chain. Within a polysiloxane chain each siloxane unit can be identical or different and preferably a2 = 1 -10 b2 = 0-1000 c2 = 0-50 d2 = 0-1 m = 1 -2000

The afore-mentioned indices should represent the average polymerisation degree P_n based on the average number molecular mass M_n.

The range for M-, D- ,T- and Q-units present in the molecule can cover nearly all values representing fluids, flowable polymer, liquid and solid resins. It is preferred to use liquid silanes or liquid linear, cyclic or branched siloxanes comprising optionally remaining Ci-C3-alkoxy or Si-hydroxy groups remaining from the synthesis. These compounds can have a low molecular weight or are condensation products, which can be partially hydrolysed, as well as siloxanes polymerized via an equilibration or condensation under the assistance of acidic catalysts.

The siloxane units with radicals R or Y can be equal or different for each silicon atom.

The preferred structures of reactive polyorganosiloxanes for component (B) in the compositions of this invention are silanes or condensed silanes/siloxanes of formula (IVa) to (IVd).

The preferred structure composed with these units are selected from

Y_r R3-rSiO(R₂SiO)_z(RYSiO)vSiR3-rYr (IVa)

Y_rMe₃-r SiO(Me2SiO)_z(MeYSiO)vSiMe₃-r Yr (IVb)

Me₃SiO(MeYSiO)VSiMe₃ (IVc) [YRSiO]_w (IVd) z = 0 to 1000 v = 0 to 100

z+v = 1 to 1000 w= 3 to 9 r= 0 or 1 , and structures of the formula

{[YSiO_3/2 ] [R⁹O₁Z₂] n₂} m2 (IVe) {[SiO_4/2}] [R⁹Oi/₂]_n2 [R₂YSiOi/₂ ] _o,oi-io [YSiO_3/2 ]_O-₅o [RYSiO_2/2 ] 0-1000 }m2 (IVf)

wherein

R⁹Oi_/2 is an alkoxy residue at the silicon atom R is defined above

n2= 0.001 to 3 a2 = 0.01 - 10 b2 = 0-1000 c2 = 0- 50 m2 = 1 to 2000

Y= hydrogen or R¹

RR⁹⁹ iiss hhyyddrrooggeenn,, nn--, iso-, tertiary- or cyclo- Ci-C₂₅-alkyl, such as methyl, ethyl, propyl, alkanoyl, such acyl, aryl, -N=CHR, such as butanonoxime, alkenyl, such as propenyl, which groups R⁹ may be substituted by one or more halogen atoms, pseudohalogen groups, like cyano.

The preferred groups for Y are hydrogen.

One preferred embodiment of the compounds of class (IVe) and (IVf) is provided by way of example by monomeric to polymeric compounds which can be described via the formula [(Me₂HSiOo 5)kSiO₄/2]m2 wherein index k can have integer or decimal values from 0.01 to (2^*m₂+2). Such liquid or resinous molecules can contain significant concentrations of SiOH- and/or (Ci-C6)-alkoxy-Si groups up to 10 mol.% related to the silicon atoms.

The indices z and v for the other types of preferred compounds with the formulas (IVa) to (IVc) are in the range of 0-1000 defined as average P_n based on the number average mol mass M_n measured by GPC versus a polystyrene standard.

Other examples of preferred suitable compounds for component (B) in the compositions of this invention include HMe₂SiO(Me₂SiO)_ZSiMe₂H, Me₃SiO- (MeHSiO)V-SiMe₃, (MeHSiO)_3-6, Si(OSiMe₂H)₄, MeSi(OSiMe₂H)₃. HMe₂SiO- (Me₂SiO)_zi(MePhSiO)_z2(MeHSiO)_vSiMe₂H, wherein z1 +z2 = z.

The component (B) can be used as a single component of one polyorganosiloxane polymer or mixtures thereof. In another embodiment it is preferred to use mixtures of formula (IVb) and (IVc). If the increase of the cure rate is required, it is preferred to use some organopolysiloxanes (B) having HMe2SiOo,5- units to adjust the cure rate to shorter times.

The molecular weight of component (B) is smaller; the functionality in (B) per molecule is higher compared to component (A).

If it is necessary to still further increase the cure rate, this can be achieved by way of example via an increase of the molar ratio of SiH to Si-alkenyl, or an increased amount of catalyst (C), or an increase in the proportion of polyorganosiloxanes (B) which contain HMe2SiOo 5 units. Thus preferred components (B) include HMe2SiOo 5 (MH groups), in order to provide faster curing rates.

In a further preferred embodiment, of the component (B) this component is selected from the group according to formula (IVa) which consist of a component (B1 ) such as YR₂SiO(R2SiO)_z(RYSiO)vSiR₂Y or formula (IVc) having a functionality of Y of 3 or more, and a component (B2) having a functionality of Y of 2 in average such as YR₂SiO(R₂SiO)ZSiR₂Y, wherein Y, R and z are as defined above.

If (B1 ) and (B2) are used together, the preferred ratio of functionality SiH (B1 ) to (B2) is from more than 0 to 70 mol-%, and more preferably from 30 to 100 mol-% of (B2), based on (B1 ) and (B2).

The molweight for the component (B) is not critical; however it is preferred such that the polyorganosiloxane component (B) has a viscosity at 25 ⁰C up from 3 to 10,000 mPa.s in the case of R= methyl. The viscosity depends upon the kind of the R and Y substituents, and the ratio of the units M, D, T and Q as well as the mol weight. For polyorganosiloxanes containing only methyl groups as R group the range of the mol weights expressed as M_n is between 136 and 100,000 g/mol. It is preferred to use liquid siloxanes with a low mol weight, i.e. smaller than 1 ,000,000 g/mol, preferably smaller than 75,000 g/mol in case of polydimethyl- methylhydrogensiloxanes.

The siloxane units with radicals R or Y can be equal or different for each silicon atom. Each molecule can bear one or more groups independently.

The crosslinker (B) should have at least more than 2 reactive groups Y per molecule whereas the chain extender (B2) have a functionality Y of 2 to 3 in average per molecule. The concentration of the reactive group Y is in the range of 0.2 to 100 mol.% Y groups related to Si atoms, i.e. for polydimethyl-methylhydrogensiloxane preferably about 0.1 -17 mmol SiY/g, the preferred range is 0.15 to 16 mmol/g. In one preferred embodiment a mixture of compounds having formula (IVc) or (IVd) are used together with (IVa) and/or (IVb), where z= 0, R= methyl and the SiH concentration is preferably >7-17 mmol SiH/g and in the second compound of (B) the index z > 0 wherein the SiH concentration has values of preferably 0.2 to 7 mmol SiH/g.

It is preferred to use compounds of formula (IVa) and/or (IVb) wherein R= aryl in particular phenyl, if adherence onto other substrates such as thermoplastic substrates has to be achieved.

The SiH-content in the present invention is determined by way of ¹H-NMR, see A.L. Smith (ed.): The Analytical Chemistry of Silicones, J. Wiley & Sons 1991 Vol. 112 pp. 356 et seq. in Chemical Analysis ed. by J. D. Winefordner.

The ratio of the crosslinker (B) to polymer (A) necessary for getting an elastomeric network, i.e. a non-sticky surface can be calculated by the ratio of reactive groups in (B) and (A). It is preferred to have an excess of reactive groups (B) : (A) of 0.7 to 20 : 1 , preferably 1.2 to 6 : 1 , more preferably 1.5 to 4 : 1 in order to ensure a certain level of multifunctional structures in the cured elastomeric network. Component (C)- (catalyst)

The inventive composition contains at least one hydrosilylation catalyst as component (C) selected from the group of organo metal compounds, salts or metals, wherein the metal is selected from the group of Ni, Ir, Rh, Ru, Os, Pd and Pt com- pounds as taught in US 3,159,601 ; US 3,159,662; US 3,419,593; US 3,715,334; US 3,775,452 and US 3,814,730.

The component (C) for the hydrosilylation reaction of the inventive composition is a catalyst compound, which facilitates the reaction of the silicon-bonded hydrogen atoms of component (B) with the silicon-bonded olefinic hydrocarbon substituents of component (A). The metal or organo metal compound can be any platinum group metal-containing a catalytic active component. The catalyst (C) includes complexes with sigma- and pi-bonded carbon ligands as well as ligands with S-,N, or P atoms, metal colloids or salts of the afore mentioned metals. The catalyst can be present on a carrier such as silica gel or powdered charcoal, bearing the metal, or a compound or complex of that metal. Preferably, the metal of component (C) is any platinum complex compound.

A typical platinum containing catalyst component in the polyorganosiloxane compositions of this invention is any form of platinum (0), (II) or (IV) compounds which are able to form complexes with the inventive phosphites. Preferred complexes are Pt-⁽⁰⁾-alkenyl complexes, such alkenyl, cycloalkenyl, alkenylsiloxane such vinylsiloxane, because of its easy dispersibility in polyorganosiloxane systems. A particularly useful form of the platinum complexes are the Pt⁽⁰⁾-complexes with aliphatically unsaturated organosilicon compound such as 1 ,3-divinyltetramethyl- disiloxane (Vinyl-M2 or Karstedt catalyst), as disclosed by US 3,419,593 incor- porated herein by reference are expecially preferred, cyclohexen-Pt, cyclooctadien- Pt and tetravinyltetramethyl-tetracyclosiloxane (Vinyl-D4).

Pt°-olefin complexes are prepared by way of example in the presence of 1 ,3-divinyl- tetramethyldisiloxane (M^V| ₂) via reduction of hexachloroplatinic acid or of other platinum chlorides by the way of example by alcohols in the presence of basic compounds such as alkali carbonates or hydroxides. Th e amount of platinum-containing catalyst component that is used in the compositions of this invention is not narrowly limited as long as there is a sufficient amount to accelerate the hydrosilylation between (A) and (B) at the desired temperature in the required time (B) in the presence of all other ingredients of the inventive compo- sition. The exact necessary amount of said catalyst component will depend upon the particular catalyst, the amount of other inhibiting compounds and the SiH to olefin ratio and is not easily predictable. However, for platinum catalysts said amount can be as low as possible due to cost reasons. Preferably one should add more than one part by weight of platinum for every one million parts by weight of the organo- silicone components (A) and (B) to ensure curing in the presence of other undefined inhibiting traces. For the compositions of this invention, which are to be used by the coating method of this invention the amount of platinum containing catalyst component to be applied is preferably sufficient to provide from 1 to 200 ppm preferably 2 to 100 ppm, especially preferred 4 to 60 ppm by weight platinum per weight of poly- organosiloxane components (A) plus (B).

Preferably said amount is at least 4 ppm by weight per sum of (A) and (B).

The hydrosilylation catalyst can also be selected from the group of photo-activatable catalysts. This catalyst capable of being photoactivated preferably contain at least one metal selected from the group composed of Pt, Pd, Rh, Co, Ni, Ir or Ru. The photo-activatable catalyst preferably comprises platinum.

The catalyst capable of being photoactivated is preferably selected among organo- metallic compounds, i.e., comprise carbon-containing ligands, or salts thereof. In a preferred embodiment the photo-activatable catalyst (C) has metal carbon bonds, including sigma- and pi-bonds. Preferably the photo-activatable catalyst (C) is an organometallic complex compound having at least one metal carbon sigma bond, still more preferably a platinum complex compound having preferably one or more sigma-bonded alkyl and/or aryl group, preferably alkyl group(s). Sigma-bonded ligands include in particular, sigma-bonded organic groups, preferably sigma- bonded Ci-C₆-alkyl, more preferably sigma-bonded methyl groups, sigma-bonded aryl groups, like phenyl, sigma-bonded silyl groups, like trialkyl silyl groups. Most preferred photoactivatable catalyst include η⁵-(optionally substituted)-cyclopenta- dienyl platinum complex compounds having sigma-bonded ligands, preferably sigma-bonded alkyl ligands.

Further catalysts capable of being photoactivated include (η-diolefin)-(sigma-aryl)- platinum complexes (see e.g. US 4,530,879).

The photoactivatable catalyst can be used as such or supported on a carrier.

The photo-activatable catalyst is a catalyst, which provides additional options to extend the bath-life time of the reactive silicon based composition in addition to the inventive phosphites and allows enlarging the processing time prior to gelling of the components.

Examples of catalysts capable of being photoactivated include η-diolefin-σ-aryl- platinum complexes, such as disclosed in US 4,530,879, EP 122008, EP 146307 (corresponding to US 4,510,094 and the prior art documents cited therein), or US 2003/0199603, and also platinum compounds whose reactivity can be controlled by way for example using azodicarboxylic esters, as disclosed in US 4,640,939 or diketonates.

Photo-activatable platinum compounds that can be used are moreover those selected from the group having ligands selected from diketones, e.g. benzoyl- acetones or acetylenedicarboxylic esters, and platinum catalysts embedded into photo-degradable organic resins. Other Pt catalysts are mentioned by way of example in US 3,715,334 or US 3,419,593, EP 1 672 031 A1 and Lewis, Colborn, Grade, Bryant, Sumpter, and Scott in Organometallics, 1995, 14, 2202-2213, all incorporated by reference here.

Catalyst capable of being photoactivated can also be formed in-situ in the silicone composition to be shaped by using Pt°-olefin complexes and adding appropriate photo-activatable ligands thereto. Th e catalyst capable of being photoactivated that can be used here are, however, not restricted to these above-mentioned examples.

The most preferred catalyst capable of being photoactivated to be used in the process of the invention are (η⁵-cyclopentadienyl)-trimethyl-platinum, (η⁵-cyclo- pentadienyl)-thphenyl-platinum complexes, in particular, (η⁵-methylcyclopenta- dienyl)-thmethyl-platinum.

The component (C) can also be selected from the group of reaction products of the platinum group metal-containing catalysts (C) and component (D) whereby each of the component is defined under (C) and (D).

The amount of the catalyst capable of being photoactivated is preferably 1 -500 ppm and preferably in the same lower range as defined for the heat-activatable hydrosilylation catalysts mentioned above.

As explained already above, the specific phosphites used in accordance with the invention interact with those conventional transition metal compounds through ligand exchange reactions, thereby influencing the hydrosilylation activity of the catalyst to provide surprisingly an excellent balance between storage stability on the one hand and reactivity at elevated temperatures upon curing.

Component (D):

The inhibitor (D) is applied in a sufficient amount in order to further retard the hydrosilylation reaction at room temperature in order to enable mixing of the components (A) to (C) as well as the dispensing and coating step without prior curing.

On the other hand the cure rate after coating should be achieved in the shortest possible time after heat or light activation within seconds especially above 40 C. With respect to the component (D) it can be referred to the phosphites having the formula:

P(OR)₃ (I)

as defined above.

The inhibitor compound (D) may be preferably incorporated therein in small amounts, such as less than 2 wt.% (20000 ppm) based on the total weight of (A) to (B). A particularly preferred range is 0.2 to 12000 ppm of component (D) related to (A) and (B).

Furthermore preferably the molar ratio of the transition metal derived from component (C) platinum to the phosphite (D) is from 1 :1 to 1 :6.

Due to their interaction with the transition metal hydrosilylation catalyst compound, the component (D) act as an inhibitor on the hydrosilylation reaction thereby increasing storage stability, i.e. enlarge the pot-life, and at the same do not exert their inhibiting activity during curing reaction.

As the case may be, it might be desirable to add additionally other conventional inhibitors, that is, to combine the inventive phosphites of component (D) with other conventional inhibitors in order to further modulate the hydrosilylation activity. In this case the preferred amounts for the component (D) included the amount of the other conventional inhibitors.

Thus, the inventive compositions may contain an appropriate amount of one or more additional conventional inhibitors. Preferably, however, the inventive compositions do not contain other phosphorous inhibitor compounds than those of formula (I). Conventional inhibitors for the platinum group metal catalysts are well known in the organosilicon art. Examples of various classes of such metal catalyst inhibitors include unsaturated organic compounds such as ethylenically or aromatically unsaturated amides, US 4,337,332; acetylenic compounds, US 3,445,420 and US 4,347,346; ethylenically unsaturated isocyanates, US 3,882,083; olefinic siloxanes, US 3,989,667; unsaturated hydrocarbon diesters, US 4,256,870, US 4,476,166 and US 4,562,096, and conjugated eneynes. US 4,465,818 and US 4,472,563; other organic compounds such as hydroperoxides, US 4,061 ,609; ketones, US 3,418,731 ; sulfoxides, amines, nitriles, US. 3,344,111 ; diaziridines, US 4,043,977; and various salts, such as US 3,461 ,185, phosphorous compounds preferably excluded. Examples thereof include the acetylenic alcohols of US 3,445,420, such as ethynylcyclohexanol and methyl butynol; the unsaturated carboxylic esters of US 4,256,870, such as diallylmaleate and dimethyl maleate; and the maleates and fumarates of US 4,562,096 and US 4,774.111 , such as diethyl fumarate, diallyl fumarate and bis-(methoxyisopropyl)maleate. The half esters and amides of US 4,533,575; and the inhibitor mixtures of US 4,476,166 would also be expected to behave similarly. The above-mentioned patents relating to conventional inhibitors for platinum group metal-containing catalysts are incorporated herein by reference.

Component (E):

The siloxane composition according to the invention may comprise further ingredients (E) as auxiliary additives. The siloxane compositions according to the invent- tion may also comprise further ingredients, by way of example solvents (E), fillers, pigments or process aids added to achieve better process properties for the invent- tive polymer composition (A) to (D).

If the compositions of the present invention optionally comprise solvents these solvents are usual organic solvents in the range of less than 20 wt.-% , preferably less than 10 wt.-% and most less than 5 wt.-% related to (A) to (D). Appropriate reactive solvents can be selected from the group of olefinic hydrocarbons such as alpha-olefins, e.g. C8-C25-alpha-olefins, preferably Ci₄-C2o-alpha-olefins or evaporable siloxanes having molweight below 518 g/mol without alkenyl or SiH groups. Mixtures of alpha-olefins can also be used.

Other additives falling under definition of component (E) are selected from the group of heat stabilzers, coloring compounds or pigments, antioxidants, biocides, fungicides, such as Preventol®, Katon®, Dowicil®, fillers, espec. spherical silsesquioxanes for getting additional antiblocking properties of release layers, anti- mist additives as disclosed in US 6,586,535 or US 2003/0134043, anchorage additives, slipping agents as disclosed in EP 819735 A1 and further auxiliary components typical for silicone release compositions. These other ingredients may be contained in said reactive silicon-based composition in a total amount of up to 20 wt.%.

If fillers are used in inventive compositions the amount of filler is between 1 to 300 weight parts, preferably 15 to 80 weight parts related to 100 weight parts of component (A). The fillers are preferably selected from the groups of hydrophilic or hydrophobic, preferably surface-modified fillers. The fillers may serve as reinforcing fillers, thickening additive, as anti-blocking or anti-friction or matting additive.

The fillers include by way of example are all of the fine-particle fillers, i.e. those having particles smaller than 100 μm (sieve residue), i.e. preferably composed of particles smaller than this value. These can be mineral fillers, such as silicates, carbonates, nitrides, oxides, carbon blacks, or silicas being fumed or precipitated silica, whose BET-surface areas are from 0.3 to 400 m²/g, these preferably having been specifically surface-hydrophobized here. Preferred silicas are, for example, Aerosil® 200, 300, HDK® N20 or T30, Cab-O-Sil® MS 7 or HS 5 more than 200 m²/g BET surface area or precipitated silicas, or wet silicas, are Vulkasil®VN3, or FK 160 from Degussa, or Nipsil®LP from Nippon Silica K.K. and others. Examples of commercially available silicas pre-hydrophobized with various silanes are: Aerosil® R 972, R 974, R 976, or R 812, or, for example, HDK® 2000 or HDK® H30, names for materials known as hydrophobized precipitated silicas or wet silicas are Sipernat®D10 or D15 from Degussa.

Surfaced treated fillers having low BET-values are preferred because the ability to build up shear thinning effects is reduced. The preferred surface treatment can be achieved with polyorganosiloxanediols, polyorganosiloxanes, alkoxy- or chloro- silanes, which allows a certain concentration of fillers having lowest degree of thickening properties and shear thinning. Another class of fillers serving as non-transparent non-reinforcing fillers are powdered quartz, diatomaceous earths, powdered crystobalites, micas, aluminum oxides, aluminum hydroxides, oxides and salts of Fe, Mn, Ti, Zn, Zr, chalks, or carbon blacks, whose BET-surface areas are from 0.3 to 50 m²/g. These fillers are available under variety of trade names, examples being Sicron®, Min-U-Sil®, Dicalite®, Crystallite® and serve as matting agents. Such fillers are used if present in a concentration of about 1 to 300 weight parts, preferably 5 to 100 weight parts related to 100 weight parts of (A).

Some very special fillers can used as matting agent, agent for increasing the mechanical modulus, or anti-blocking agent, these filler are selected from the group of spherical or fiber shaped thermoplastic powders or fibres such as PTFE-powders, PTFE-emulsions or polyamide, polyurethane or silsesquioxanes powders, thermoplastic fibers cured silicone elastomers or resins und are used if present in amounts of up to 10 weight parts related to 100 weight parts of (A). Tradenames are Teflon® emulsions, Nylon®-powders, Tospearl®, Acemat® , Twaron®, Kevlar®, Dralon®, Diolen® etc. This type of filler especially if the particles have a spherical shape can preferably be used as anti-blocking agents in the release layer and can give an especially soft touch and low friction properties of the rubber surfaces.

Another class of additives are stabilizers, such as heat stabilizers which can be selected from the group of metal compounds, organic or inorganic salts, complexes of Ce, Fe, La, Mn, Ti and Zr. Levelling agents, mold release agents are selected from the group consisting of polyether-siloxanes, polyols, polyethers, polyhalides, fatty alcohol or fluoroalkyl derivatives.

Another class of important auxiliary additives are adhesion promotors, which can either be incorporated in the composition (A) to (D) or applied in an appropriate form as primer applied prior onto the substrate foreseen for getting adhered to the rubber composition under curing.

Adhesion promotors are selected from the group of preferably alkoxysilanes, their condensation product alkoxysiloxanes bearing further organofunctional groups linked over Si-C-bonds, in particular epoxyalkyl, acryloxyalkyl, methacryloxyalkyl, NCO-alkyl, aminoalkyl, urethanealkyl, alkenyl which further can bear SiH groups. Such silanes/siloxanes can be combined with condensation catalyst selected from the group of organometal compounds of Ca, Zr, Zn, Sn, Al or Ti and /or polycyclic aromatic compounds having reactive groups such as alkenyl substituted aromatic biphenyl ethers, esters. The effects of adhesion can be further improved by the addition of selected compounds of component (B),e.g. incorporated by reference US 4,082,726, US 5,438,094; US 5,405,896; US 5,536,803; US 5,877,256; US 6,602,551 ; EP 581504 A; and EP 875536.

The present invention further relates to the use of one or more phosphites of the formula (I) for the manufacture of hydrosilylation-cuhng polyorganosiloxane and/or silane compositions. Further the present invention relates to the use of one or more phosphites of formula (I) as inhibitors of the hydrosilylation reaction in the curing of polyorganosiloxane compositions and/or silane compositions.

In another preferred embodiment the present invention relates to hydrosilylation- curing polyorganosiloxane compositions and/or silane compositions comprising in parts per weight (pw):

100 pw of component (A) as defined above,

0.1 - 200 pw of component (B) as defined above, 0.1 - 1000 ppm of the transition metal contained in component (C) related to (A) and (B) each as defined above,

0.2 to 12000 ppm of component (D) related to (A) and (B), each as defined above, and 0 to 200 pw of component (E) as defined above.

In polyorganosiloxane and/or silane compositions curable by hydrosilylation according to the invention the molar ratio of platinum to phosphite of formula (I) is preferably from 1 :1 to 1 :6.

In another preferred embodiment the present invention relates to a so-called ^'One- Part^'-hydrosilylation-curing polyorganosiloxane and/or silane composition, comprising at least one or more phosphites of formula (I).

Under the expression ^'One-Part^'- hydrosilylation-curing polyorganosiloxane and/or silane compositions it is meant in accordance with the present invention, that composition (A) to (D) and optionally (E) comprises all ingredients to get cured under the appropriate conditions, in particular at an increased temperature level of higher than 25 ⁰C.

The present invention further relates to cured polyorganosiloxane and/or silane compositions obtained by curing the hydrosilylation-curing polyorganosiloxane and/or silane compositions as defined above.

Further the present invention relates to the use of the polyorganosiloxane and/or silane compositions of the invention curable by hydrosilylation for the manufacture of shaped formed articles, extruded articles, coatings, and sealants.

In particular, in the manufacture of shaped articles formed under extrusion there is an increasing demand for curing such rubber articles via a hydrosilylation reaction while replacing peroxides. The cure rates necessary for such technology are rather high i.e. the cure time is short, and is in general below 2 min at 110 ⁰C in order to get a bubble free cured elastomehc article. These requirements can be achieved with the hydrosilylation-cuhng polyorganosiloxane and/or silane compositions according to the invention. At the same time the hydrosilylation-curing poly- organosiloxane and/or silane compositions according to the invention have storage stability at 25 ⁰C of preferably more than 30 days.

The term storage stability used in accordance with the present invention means the tio-time at 25 ⁰C, which is the time wherein 10 % of the elastic modulus of the fully cured material at 25 ⁰C is reached, after preparation of the reactive composition. On the other hand the cure time of the hydrosilylation-curing polyorganosiloxane and/or silane compositions is the time t₉₀ at 110 ⁰C, which is the time wherein 90 % of the elastic modulus of the fully cured material at 100 ⁰C is reached after preparation of the reactive composition. The elastic modulus is measured with a Rheometer MDR 2000 of Alpha Technologies.

Another important application of the hydrosilylation-curing polyorganosiloxane and/or silane compositions according to the invention are siloxane coatings e.g. release coatings for thermoplastic films which must be cured below 110 ⁰C within a reasonable short curing time given by the band speed of the coating machines which is usually between 50 - 1000 m/min whereby the coating thickness is usually between 0.05 - 1 mm.

The present invention further provides a process for the manufacture of the hydrosilylation-curing polyorganosiloxane, comprising mixing one or more

(A) polyorganosiloxanes and/or silanes having in average at least two alkenyl groups,

(B) one or more polyorganosiloxanes and/or silanes having in average at least two SiH groups, (C) one or more transition metal compounds, wherein the transition metal is selected from group consisting of nickel, ruthenium, rhodium, palladium, osmium, iridium,and platinum,

(D) one or more phosphites as defined above, and (E) optionally one or more auxiliary agents, in a mixing apparatus.

Preferably the following procedure is applied to prepare the preferred 'One-Part' - composition of the invention.

That is, the components (A) to (E) are mixed first to non-reactive compositions, that is, compositions which do not contain (A), (B) and (C) at the same time.

Although the ^'One-Part'-composition of the invention has a very high stability, i.e. a very long storage time, it is nevertheless in practice preferred to prepare and supply two or three partial compositions, wherein each partial composition does not contain all of the components (A) to (E). Those partial compositions can be stored practically for more than 100 days. The manufacturer usually prepares the reactive composition i.e. mixing of the partial compositions. The reactive composition has then still a storage stability of more than 30 days.

Those preferred partial compositions are most preferably two partial compositions containing the following components:

- (A) + (B) + (D) + optionally (E), e.g. fillers; (A) + (C) + optionally (E), e.g. fillers.

Such a combination of the partial compositions is preferred because a 1 :1 mixture per volume is achievable, which easily to be mixed by static mixers. Another advantage of such a combination of partial compositions is the avoidance of the simultaneous presence of (B) and (C) which detrimental because of a possible occurrence of discolouration. On the other hand the combination of (A) and (C) has a stabilizing effect on the transition metal catalyst component (C).

The partial compositions as defined before are preferably prepared for example with in a mixing apparatus selected from kneaders, dissolvers, single or twin screw extruders, LIST-mixing apparatuses, BUSS-co-kneader, Banbury mixers or ^'press- mixers^' of Voith, or two roll-mixers.

The reactive preferably ^'One Part^'-compositions are preferably prepared by mixing the partial compositions by mixing the with them for example in a mixing apparatus selected from static mixers, kneaders, like two blade kneaders, dissolvers, single or twin screw extruders, LIST-mixing apparatuses, BUSS-co-kneader, Banbury mixers or ^'press-mixers^' of Voith, two roll-mixers, or multi roll coating mixtures.

Accordingly the present invention also relates to the partial composition comprising components (A) + (B) + (D) + optionally (E).

Preferred compositions:

The inventive compositions preferably applied as ^'One-Part^'-composition can be used preferably as a so-called paper release coating, as a liquid rubber or as a high consistency rubber composition having optionally incorporated reinforcing fillers, which for example have the following compositions:

(A) 100 pw. of one or more polyorganosiloxanes and/or silanes having in average at least two alkenyl groups and a viscosity of 50 mPa.s - 100 kPa.s at 25 ⁰C,

(B) 0.1 to 100 of one or more polyorganosiloxanes and/or silanes having in average at least two SiH groups in an amount to achieve a molar ratio of SiH : Si-alkenyl groups of 0.8 to 6 : 1 , (C) 1 - 500 ppm calculated as metal related to (A) and (B) of one or more transition metal compounds, wherein the transition metal is selected from group consisting of nickel, ruthenium, rhodium, palladium, osmium, iridium, and platinum,

(D) one or more phosphites according to formula (I) preferably in an amount to achieve a molar ratio of 1 :1 to 6:1 of component (D) to the metal atom of component (C), and

(E) 0 - 200 p.wt. of one or more reinforcing silicas having a BET - surface of more than 50 m²/g and optionally further auxiliary additives.

EXAMPLES

Synthesis of the phosphite inhibitors

The trisarylphosphites have been synthesized according to the following reaction scheme

3 RO M⁺ + PCI₃ — — *► P(OR)₃ + 3 MCI

R= as defined above M= Li, Na wherein PCb and the corresponding metal alkoxide obtained from a reaction of an alcohol with sodium hydride or n-butyl lithium undergo a reaction in dried tetrahydro- furane, see also A. Earnshaw, N. Greenwood (1997): The Chemistry of the Elements - Second Edition.

General procedure for the synthesis of the phosphites

A solution of the selected alcohol in THF (tetrahydrofurane), which has been dried over sodium and sodium hydride, was added dropwise under vigorously stirring under a dry argon atmosphere to a suspension of NaH dissolved in THF or n-butyl lithium dissolved in hexane at room temperature (25 ⁰C). After the indicated period of stirring and cooling to room temperature the solvent was removed under reduced pressure to dryness, then hexane was added and the suspension containing the organic phase, some hexane and salts are separated by filtration using a canula system. The filtered organic phase was concentrated under reduced pressure followed by crystallization step, wherein the residue has been placed in a freezer at

-15 ⁰C for crystallization. The solid product was purified by decantation at -78 C and dried under vacuum (20 mbar).

Example 1 : Tri(phenyl)phosphite (1)

Commercially available e.g. from Aldrich CAS [101 -02-0] and other suppliers. Example 2: Synthesis of tris(2-allylphenyl)phosphite (2)

This compound was prepared starting from 5 g (3.73 mmol) of 2-allylphenol, 1.5 g of NaH (6.25 mmol) and 1.53 g (11.1 mmol) of PCI₃. After addition Of PCI₃ mixture was stirred for 24 h at room temperature. At the next step the content was heated up to 50 ⁰C and the reaction was conducted for 2 hours in this temperature. Product was isolated at room temperature. Yield 4.32 g (90 %).

¹H NMR (300 MHz, C₆D₆, 300 K) δ(ppm) = 7.19-6.95 (m, 12H, Aryl); 5.83 (m, 3H, - CH=); 4.92 (m, 6H, =CH₂); 3.27 (d, 6H, -CH₂-)

¹³C NMR (75.42 MHz, C₆D₆, 300 K) δ(ppm) = 136.15; 131.47(d); 130.39; 127.18; 124.11 ; 120.21 ; 120.05; 115.83; 34.37

³¹P NMR (121.47 MHz, C₆D₆, 300 K) δ(ppm) = 130.06.

Example 3: Synthesis of tris(2-biphenyl)phosphite (3)

This compound was prepared starting from 5 g (29 mmol) of 2-Phenylphenol, 18.75 ml (30 mmol) of 1.6 mol/L solution of n-butyl lithium in hexane and 1.21 g (8.8 mmol) of PCI₃. After addition of PCI₃ mixture was stirred for 24 h at 50 ⁰C. To the crude product 2x50 ml of benzene was added. After evaporation of solvent white solid was washed with hexane. Yield 4.12 g (87 %).

¹H NMR (300 MHz, C₆D₆, 300 K) δ(ppm) = 7.34 (d), 7.31 (d), 7.15 (m), 7.09 (m), 7.07 (m), 6.90 (m), 6.85 (m) 1³C NMR (75.42 MHz, C₆D₆, 300 K) δ(ppm) = 149.18 (d, J_c-P = 4.25 Hz), 138.34, 134.36 (d, Jc-_P = 4.86 Hz); 131.33; 129.95(d); 128.66, 128.29, 127.24, 124.33(d), 121.68, 121.39, 121.24

³¹ P NMR (121.47 MHz, C₆D₆, 300 K) δ(ppm) = 127.58. Example 4: Synthesis of tris(2,6-diphenylphenyl)phosphite (4)

This compound was prepared starting from 5 g (20.5 mmol) of 2,6-diphenylphenol, 0.8 g of NaH (33.5 mmol) and 0.845 g (6.15 mmol) of PCI₃. After addition of PCI₃ mixture was stirred for 24 h at 60 ⁰C. Crude product was dissolved in 80 ml of toluene, heated up 100 ⁰C and then filtered off by a cannula system. Yield 4.00 g (85 %).

¹H NMR (300 MHz, C₆D₆, 300 K) δ(ppm) = 7.50-7.20 (m, 9H); 7.08 (m, 7H); 6.99- 6.76 (m, 23H) 1³C NMR (75.42 MHz, C₆D₆, 300 K) δ(ppm) = 145.22; 142.78, 139.52; 136.75; 135.66; 130.50; 130.28; 129.66; 126.30; 126.37; 124.52

³¹ P NMR (121.47 MHz, C₆D₆, 300 K) δ(ppm) = 145.33.

Synthesis of the transition metal complex compounds

The synthesis follows a pathway in that e.g. the well-known divinyl- tetramethyldisiloxane (^'DVTMDS^') bridged binuclear platinum complex (Karstedt's catalyst) can be cleaved by any nucleophile (e.g. phosphite), giving a mononuclear platinum complexes, according to following equation:

Example 6: Synthesis of (1 ,3divinyldisiloxane)[tri(2-allylphenyl)phosphite]- platinum(O) complex (2.2)

Portions of 1.00 g (2.32 mmol) of (2), and 3 g of Karstedt's catalyst (14.79 % solution in xylene) (2.27 mmol Pt) were placed in a Schlenk's flask in argon atmosphere. The reaction was conducted for 24 hours at room temperature on intense stirring with a magnetic stirrer. After this time, the mixture was filtered off by a cannula system and the filtrate was concentrated. The residue was washed three times with pentane by decantation at -70 ⁰C. The solvent was evaporated and the complex obtained was dried under vacuum for 24 h at 50 °C.Yield 1.77 g (96 %).

Test conditions for reactivity, i.e cure rate and inhibition (pot-life, storage stability)

The phosphites (1 ) to (4) were tested in a hydrosilylation reaction, whereby the phosphite was applied as component (D). The alkenyl component (A) is realized by a liquid linear polydimethylsiloxanes having 2 vinyl endgroups, the Si-hydrogen component (B) is realized by a multifunctional polydimethyl-methylhydrogensiloxane (crossl inker), and as component (C) a (platinum)-Karstedt catalyst was choosen.

The testing composition consists of 100 g of component (A) which is a vinyl terminated polydimethylsiloxane with an average chain length of 150 units and a viscosity of 200 to 300 mPa.s (25°C). 1.32 mol.%, 0.177 mmol/g Of -CH=CH₂ groups attached to the Si atoms from Momentive Performance Materials.

As second component 7.7 g of the component (B) are admixed, which is a polydimethyl-methylhydrosiloxane, having 1.23 mol.%, of SiH groups represented by the general formula MD^H5oDnoM with 4.42 mmol SiH/g and a viscosity of 35 mPa.s. As third component a solution of 7.8 to 50.1 mg (D) 20-wt.% in toluene providing a molar P : Pt ratio of 1 : 1 to 4: 1 are admixed with a Krups mixer at 25 ⁰C and ambient air. The weights of (A) and (B) provide a molar ratio of in terms of [≡SiH] to [≡Si-CH=CH₂] of 1.93 to 1.

After getting mixed (A), (B) and (D) a solution of the component (C) of 42.2 mg (4.76 10^~3 mmol) of the Karstedt catalyst solution (2.2 wt.% Pt) in xylene was distributed in the components (A)₁(B) and (D) corresponding to 10 ppm Pt as metal in total of (A) and (B).

The time for gelling (doubling of viscosity) at 25 ⁰C was measured as pot life (as measure for storage stability). The relative curing time was measured as the time required until disappearance of 95 % of the initial SiH-signal in the ¹H-NMR after storage (A) to (D) at 120 ⁰C. In addition the progress of the reaction has been monitored by DSC-method (Differential Scanning Calorimetry). All samples were mixed well for half an hour in before the DSC analysis. The DSC measurements were made using a DSC 204 NETCH. The instrument was calibrated with indium (ΔH = 28.4 J/g), the heating rate is 10 °K/min running from 20 to 220 ⁰C, hold for 5.0 min at 30 ⁰C under helium atmosphere. The values are average values of 3 runs for each composition.

All the manipulations after mixing were carried out under argon using standard Schlenk and vacuum techniques. ¹H-, ¹³C- and ³¹P-NMR-spectra were recorded on a Varian Gemini 300 VT and Varian Mercury 300 VT spectrometers in benzene-d6, acetone-d6.

The chemicals were obtained from the following sources: alcohols, benzene-d₆ and acetone-dβ, Karstedt catalyst from Aldrich, Si-vinyl and SiH-siloxanes from Momentive Performance Materials, solvents from POCH Gliwice (Poland). Triphenyl phosphite is commercially available from Aldrich.

Table 1

Potlife at Curing time at 25 ⁰C 120 ⁰C

Inhibitor Structure [Pt] : [L]

[h] [sec]

1 : 1 > 168 600

1 :5 > 168 2400

ured ured

The pot-life times and curing times increase with the increasing ratio of [P] : [Pt], i.e. more phosphite introduced via component (D) increases that time as shown by phosphite (4). The comparison phosphite (1 ) results in a pot-life time of more than 168 h ( >7 days), whereas the curing time is 600 to 2400 sec depending on the molar ratio of [P] : [Pt] of the components (D) to (C).

The phosphites (2) and (3) provide a high reactivity (short cure time ca. 60-165 sec) and at the same time a high storage stability (long pot-life) at room temperature compared to comparative example (1 ). For compound (4) one can observe a high reactivity and shorter pot-life in particular for [P] : [Pt] = > 5:1. Another advantage of the compound (2) is the low melting point, i.e. compound (2) is a liquid at 25 ⁰C, which enables a good dispersibility in the siloxane matrix. The addition of the phosphites (2) and (3) into the test composition surprisingly shortens the curing times, wheras the pot-life is still at level of more than 7 days after having prepared the reactive composition. This effect can be used particularly in a kind of ^'One-Part^'-composition, which is potentially highly reactive on the one hand but can be stored after getting mixed for 7 days on the other hand.

Claims

CLAIMS:

1. Hydrosilylation-curing polyorganosiloxane compositions and/or silane compositions, comprising one or more phosphites having the formula:

P(OR)₃ (I)

wherein R is an aromatic group, substituted by at least one aromatic group or substituted by at least one alkenyl group.

2. Hydrosilylation-curing polyorganosiloxane compositions and/or silane compositions according to claim 1 , comprising:

(C) one or more transition metal compounds, wherein the transition metal is selected from group consisting of nickel, ruthenium, rhodium, palladium, osmium, iridium, and platinum, (D) one or more of the phosphites as defined in claim 1 , and

(E) optionally one or more auxiliary agents.

3. Compositions according to claim 1 or 2, wherein in the formula (I) the aromatic groups are phenyl groups.

4. Compositions according to any of claims 1 to 3, wherein in the formula (I) the alkenyl groups are selected from vinyl and allyl.

5. Compositions according to any of claims 1 to 3, wherein R is phenyl substituted by one to three phenyl groups.

6. Compositions according to any of claims 1 to 3, wherein R is phenyl substituted by one to three allyl groups.

7. Compositions according to any of claims 1 to 6, wherein the phosphites of the formula (I) are selected from the group consisting of:

Tris(2,6-diphenyl)phenyl phosphite:

Tris(3-phenyl)phenyl phosphite,

Tris(4-phenyl)phenyl phosphite,

and

Transition metal compound, comprising at least one phosphite having the formula:

P(OR)₃ (I),

wherein R is as defined above, as a ligand, and wherein the transition metal is selected from group of nickel, ruthenium, rhodium, palladium, osmium, iridium, and platinum.

9. Transition metal compound, obtained by reacting a transition metal compound, wherein the transition metal is selected from group consisting of nickel, ruthenium, rhodium, palladium, osmium, iridium, and platinum, with at least one phosphite as defined in any of claims 1 to 7.

10. Transition metal compounds according to claims 8 and 9, wherein the transition metal is platinum.

11. Use of one or more phosphites as defined in any of claims 1 to 7 for the manufacture of hydrosilylation-curing polyorganosiloxane and/or silane compositions.

12. Use of one or more phosphites as defined in any of claims 1 to 7 as inhibitors of the hydrosilylation reaction in the curing of polyorganosiloxane compositions and/or silane compositions.

13. Hydrosilylation-curing polyorganosiloxane compositions and/or silane compositions according to any of claims 1 to 7, comprising:

100 pw of component (A),

0.1 - 200 pw of component (B)

0.1 - 1000 ppm of the transition metal contained in component (C) related to (A) and (B),

0.2 to 12000 ppm of component (D) related to (A) and (B), 0 to 200 pw of component (E).

14. Hydrosilylation-curing polyorganosiloxane compositions and/or silane compositions according to any of claims 1 to 7 and 13, wherein the molar ratio of platinum to the phosphite is from 1 :1 to 1 :6.

15. One-part hydrosilylation-curing polyorganosiloxane and/or silane compositions, comprising at least one or more phosphites as defined in any of the claims 1 to 7.

16. Cured polyorganosiloxane and/or silane compositions obtained by curing the hydrosilylation-curing polyorganosiloxane and/or silane compositions as defined in any of the claims 1 to 7, and 13 to 15.

17. Use of the hydrosilylation-curing polyorganosiloxane compositions and/or silane compositions of any of claims 1 to 7, and 13 to 15 for the manufacture of shaped formed articles, extruded articles, coatings, and sealants.

18. A process for the manufacture of the hydrosilylation-curing polyorganosiloxane compositions of claims 1 to 7, and 13 to 15, comprising mixing

(A) one or more polyorganosiloxanes and/or silanes having in average at least two alkenyl groups,

(B) one or more polyorganosiloxanes and/or silanes having in average at least two SiH groups, (C) one or more transition metal compounds, wherein the transition metal is selected from group consisting of nickel, ruthenium, rhodium, palladium, osmium, iridium, and platinum,

(D) one or more phosphites as defined in any of the claims 1 to 7, and

(E) optionally one or more auxiliary agents

in a mixing apparatus.