WO2006010764A1 - Method for production of a surface-treated oxidic filler - Google Patents

Abstract

The invention relates to a method for production of a surface-treated filler, compositions comprising said filler and use thereof.

Description

 Process for the preparation of a surface-treated oxidic filler

The present invention relates to a process for the preparation of a modified, in particular surface-modified, oxidic filler, the filler enthal¬ tend compositions and their use. It also relates to storage-stable polysiloxane compositions which after vulcanization give permanently water-wettable elastomers and their use as dental impression materials or pressure pads.

Molding compounds often consist of a binder or polymer and a filler. Thus, silicone rubbers, when they are used for the molding of objects such as teeth, consist of a polydimethylsiloxane and a finely divided silica. Silicas cause a disperse phase in high or low viscosity liquid polymer phases such as a polydimethylsiloxane both a thickening and a higher rubber mechanical strength when they are cured by cross-linking to an elastomer. The thickening causes an increased viscosity level at low to medium shear rate D of 0.001 to 10 s ^-1 . In the compositions with oxidic fillers such as silica, a certain structural viscosity is almost always observed, ie a change in viscosity with the shear rate gradient or even a yield value does not have the pure polymer of this size.

The thickening influence of e.g. Silica increases when polar polymers such as polyethers are present. These are used in particular for the modification, in particular for the hydrophilization of the surfaces of polysiloxane compositions.

WO 98/58997 or US Pat. No. 4,785,047 attempt to overcome the above-described problem by the use of a silica which is obtained by a so-called ^' in situ ^' treatment, in which the silica initially in the presence is mixed by silazanes and water in polyorganosiloxanes and nachträg¬ Lich with further hexamethyldisilazane is brought into contact. However, especially in the presence of polyethers, the silicas used still lead to a pronounced thickening of the uncured polymer compositions.

Furthermore, WO 00/61074 uses a silicic acid for producing a composition which is used for the production of hydrophilic duplicating compositions. The silicas treated by the process described therein do not provide for the intermediate removal of water and other low-boiling constituents. However, the use of these silicas also leads in the presence of small amounts of surfactants, in particular of polyethers, in the polymer composition to a strong thickening, which makes their processing difficult.

Thus, there is the problem that, on the one hand, one wishes to achieve a sufficiently high (rubber) mechanical strength with the silicic acids in the cured polymer compositions, but at the same time strives for the flowability of the uncured polymer compositions, ie a low viscosity and structural viscosity. so as not to impair its applicability in the production of impression materials or coatings.

In particular, this problem exists if it is intended to produce surface-modified, in particular hydrophilized, filler-containing polysiloxane compositions having improved wettability by water through the presence of surfactants, such as polyethers.

The inventors have now surprisingly found it possible to provide a process by means of which oxidic filler can be obtained which does not impair the flowability of uncured polymer compositions and at the same time does not lead to deterioration of the (rubber) mechanical properties in the cured polymer composition. The inventors also found that it using this special filler, it is also possible to produce, in particular, polymer-containing polymer compositions which have a low viscosity and intrinsic viscosity, in spite of the effect of the polyethers which reinforces the thickening effect of the silica.

The inventors found that a two-stage surface treatment with a step of separating off vaporizable constituents surprisingly leads to a surface-treated filler which achieves the object described above.

Furthermore, the inventors have found compositions with which silicone rubbers can be prepared which, after crosslinking, have a persistently long hydrophilicity and which can be used, for example, as impression compounds for dental impressions.

In general, two-stage hydrophobing processes have been known in the literature. Thus, US Pat. No. 4,785,047 describes a two-stage process in which an amount of more than 15% by weight and in the second step an amount of more than 5% by weight of the treatment agent per silica are used in the first step. WO 98/58997 discloses a method in which max. 8% by weight of treatment agent are used, a division into a first or second step or a defined total amount are not disclosed. WO 00/61074 (Rhodia) claims the preparation of hydrophilic addition-crosslinkable silicone rubber compositions using known surfactants and especially hydrophobized silicas. The cured elastomers can be used as a dental material or when printing by the pad-printing process. The silicic acid is hydrophobized according to a cited prior art in a single step with the addition of hexamethyldisilazane twice. The addition occurs before and during the incorporation of the silica into the polymer. The addition of water is optional. WO 98/58997 discloses a process in which in the first step an amount of more than 1 to 3 wt .-% and - A -

in the second step, an amount of from 10 to 15% by weight of treatment agent per silicic acid is used.

However, throughout the prior art it has not been described that the effectiveness of the second step can be markedly increased by the intermediate separation of the low-boiling components after the first hydrophobic treatment, especially if the quantities of surface treatment agent used are kept within certain limits and if water is used in the following stage or step is not added to the steps of re-adding a hydrophobing agent.

The novel polymer-filler mixtures according to the invention, in particular based on polyorganosiloxanes, in particular those which are prepared with the addition of polyethers, are particularly suitable for producing highly flowable, self-leveling, hydrophilic or antistatic silicone rubbers which are eg can be used as addition-crosslinkable Silikonkaut¬ schuke for Dentalabformassen or ink stamp in Päd Printing process advantageous.

It is known to treat hydrophobic surfaces such as those of silicones with relatively low molecular weight surfactants: In K.B. Norling, M.H. Reisbick; The Journal of Prosthetic Dentistry 42, 342-347 (1979), e.g. with nonylphenoxy poly (ethyleneoxy) ethanol. DE-A-37 21 784 discloses the use of proteins, hydrophilic silicone oils and nonionic surfactants, EP-A-231 420 describes the use of siloxane polymers with alkylene ether groups.

The systems mentioned here are only permanently hydrophilic to a limited extent since the surface-active compounds partly separate from the polydiorganosiloxane, migrate on the surface thereof or are extracted by the poor bond to the polyorganosiloxane in contact with aqueous media. The water wettability is then, for example, by rinsing with water, decorating during disinfecting, producing duplicates with the aid of water-containing impression materials, such as gypsum lost before the desired impression with reproducible wetting properties of the silicone mold is achieved after demolding from the moist replicate surface.

From DE 1 519 412, US Pat. No. 6,657,959, US Pat. No. 6,013,711, US Pat. No. 6,201,038 and EP 602128, alkylene ether copolymers are known as anti-fogging agents or hydrophilic silicone rubbers which, by using siloxane-soluble polyethers or reactive polyethersiloxanes which bind to siloxane by hydrosilylation reaction contain. These reactive polyethersiloxanes contain e.g. Vinyl groups or optionally Si-H groups.

EP-A-231 420 discloses silicone impression compositions in which the attachment of polyether units to a component of the polyorganosiloxane is suggested to obtain permanently water-wettable vulcanizates. In this composition and those of DE 1 519 412, however, the production-related content of hydrosilylation catalyst still present in the polyethers limits any use in reactive polysiloxane rubbers with a minimum storage time of several days.

EP-A-398 745 and EP-A-429 069 disclose silicone rubber compositions using polyether radicals bonded to siloxanes. Finally, EP 602 128 solves the problem of storage stability of hydrophilic silicone rubbers with chemically bound polyether part by the use of a noble metal-free polyethersiloxane, according to the aforementioned proposals.

Despite this contribution to the provision of storage-stable polyether-containing additives in silicone rubbers which crosslink by noble metal catalysts, the problem of thickening in silicic acid-containing silicone rubbers caused by polyethers could not yet be solved. To solve this problem, a process for the preparation and use of oxidic fillers is provided in the invention, which produces fillers which cause only a very small thickening with polyethers.

The present invention therefore provides a process for the preparation of an oxidic filler comprising the steps:

a. Mixing at least one reactive silane i) with at least one oxidic filler, if appropriate in the presence of water, b. Separating low-boiling constituents contained in the mixture, c. Add at least one reactive silane ii), without adding water and optionally heating the mixture.

Step a) Step a) involves mixing at least one reactive silane i) with at least one oxidic filler, if appropriate in the presence of water. Step a) is useful in a temperature range of about room temperature (25 ⁰ C) to about 200 ⁰ C and about normal pressure (1013 mbar) to about 30 bar. Preferably, the mixing is carried out at room temperature and atmospheric pressure. The mixing is carried out in a conventional mixing apparatus, such as kneaders, dissolvers, mixing turbines, screw mixers, extruders, stirred tanks, preferably in a kneader or dissolver. The mixing time ranges, for example, from about 10 minutes to about 400 minutes. Step a) is carried out in the presence of water when the reactive silane i) is selected from organosilazanes, hexaorganodisilazanes, trialkylsilylamines, trialkylsilyloximes, trialkylsilylamides or organoalkoxysilanes. In this case, water serves as a reaction partner for the formation of hydroxy-functional intermediates of said reactive silanes. When organosilanols are used as reactive silanes i), the addition of water may be omitted, but this does not preclude the addition of water. In addition, water can also serve as a liquid continuous phase in step a) in which the reactive silane i), the oxidic filler, the abovementioned intermediates and cleavage products from the reaction of water and reactive silanes i) are dispersed or dissolved. The liquid continuous phase may also be formed by other solvents, such as inorganic or organic solvents, low or high viscosity polymers. That is to say that the polymers whose reinforcement is intended to be the filler can already be present during the modification of the filler, or in other words that the modification of the filler in the presence of the polymers or the curing composition to be reinforced, for example in the presence component a) of a curable polyorganosiloxane composition described below can take place.

The amount of water used in step a) must be at least such that the said reactive silanes i) can be hydrolyzed. Expediently, sufficient water is added to the mixture in step a) so that the reaction products of the reaction of the reactive silane i) with the water can still remain in the aqueous phase or can be sufficiently diluted. Preferably, the amount of water is at least about 5 parts by weight of water per 100 parts by weight of the silane i), preferably the amount of water used is about 10 to 50 parts by weight per 100 parts by weight of the reactive silane i).

If water is used as the liquid continuous phase, this amount will be reached in any case. In this case, the amount of water used is preferably at least about 300 parts by weight per 100 parts by weight of the oxidic filler.

When a liquid continuous phase other than water is used in step a), the amount thereof is preferably at least about 150 parts by weight per 100 parts by weight of the oxidic filler. The water used in step a) may be separately added water and / or water introduced with the filler.

Step a) of mixing the reactive silane i) with the oxidic filler can optionally also be carried out in the presence of a catalyst. The presence of a catalyst is preferably carried out when organoalkoxysilanes or organosilanols are used as reactive silanes i). The catalysts include spielsweise: Weak bases and acids with pK _a values between 4 to 9. Examples include: ammonia, alkylamines, carboxylic acids, bicarbonates, Hydrogenphospate, hydrogen sulfates, acidic salts of carboxylic acids, Kohlensäure¬ semester, etc. The catalyst is suitably used in amounts of 0.5 to 20 wt .-% based on the amount of the reactive silane i).

The amounts of the reactive silane i) and of the oxidic filler used in step a) depend inter alia on its type, for example on the specific surface of the filler. In order to achieve a sufficient modification of the filler in step a), it is expedient to use at least about 3 parts by weight of the reactive silane i) per 100 parts by weight of the oxidic filler. An amount of less than 3 parts by weight of the reactive silane i) per 100 parts by weight of the oxidic filler is generally less preferred, since it must be expected that the surface modification is too small. The reactive silane i) is preferably used in an amount of at most about 30 parts by weight of the reactive silane i) per 100 parts by weight of the oxidic filler. On the one hand, exceeding this upper limit makes no economic sense, on the other hand, depending on their specific surface area, the fillers can only absorb a certain amount of the reactive silane i), and the specific surface of the oxidic fillers currently available on the market leads to a restriction of the silane that can be bound to the surface. A preferred amount range of the reactive silane i) used is about 8 to 15 parts by weight of the reactive silane i) per 100 parts by weight of the oxidic filler. The reactive silane i) used in step a) is a silane which is capable of forming, if appropriate by reaction with water, suitable reactive intermediates capable of reacting with the surface of an oxidic filler. Preferably, such reactive silanes i) are selected from the group consisting of organosilazanes, hexaorganodisilazanes, organosilanols, trialkylsilylamines, trialkylsiloximes, trialkylsilylamides or organoalkoxysilanes. Preferably, the reactive silanes i) are selected from hexaorganodisilazanes and organosilanols. Particularly preferred are hexamethyldisilazane, 1, 3-divinyltetra methyldisilazane, trimethylsilanol and vinyldimethysilanol.

The oxidic filler used in step a) may be any metal oxide. It is expedient to choose from silicic acids, aluminum oxides, aluminum hydroxides, titanium oxides which are prepared by various processes, such as flame hydrolysis, precipitation processes, etc. The BET specific surface area of the oxidic fillers is preferably at least about 20 m ² / g, more preferably at least about 40 m ² / g, more preferably at least about 100 m ² / g, even more preferably at least about 130 m ² / g. Examples include fumed silicas such as Aerosil (Degussa), HDK (Wacker), Cab-O-Sil (Cabot). A preferred filler which is treated according to the invention is silica, preferably having a BET specific surface area of at least about 130 m ² / g.

According to the invention, it is also possible to use a mixture of one or more, in particular two fillers with different specific surfaces. By suitably selecting various, in particular, two fillers having different specific surface areas, it is possible to further enhance the effect of the invention, namely not to impair the flowability of uncured polymer compositions and at the same time not to obtain deterioration of the (rubber) mechanical properties in the cured polymer composition , Step b)

Step b) comprises separating low-boiling constituents from the mixture obtained in step a) by adjusting such pressure and temperature conditions that the low-boiling constituents contained in the mixture evaporate. Such low-boiling constituents are, in particular, constituents having a boiling point of less than 180 ° C. under atmospheric pressure (1013 mbar), such as water, ammonia, alcohols, amines, hydroxylamines, amides and silanols which have formed in step a). Suitable pressure and temperature conditions are for example temperatures of 30 to 250 ⁰ C and pressures of about 0.01 to 1013 mbar. Temperatures of more than 25O ⁰ C are less preferred in step b), since it can lead to decomposition of the liquid continuous phase, in particular when it comes to liquid polymers. Moreover, such a high temperature is less desirable from an economic and ecological point of view. Preferably, the evaporation of the low-boiling constituents takes place at a temperature of 120 to 180 ° C and vacuum (10- 50 mbar). Step b) expediently takes place in the mixing apparatus mentioned in step a) with stirring or kneading. Step b) is expediently carried out until the proportion of low-boiling components of the mixture has been reduced to less than 10% by weight, more preferably less than 5% by weight, even more preferably less than 0.5% by weight , The proportion of low-boiling constituents in the mixture obtained in step b) is advantageously determined by keeping the mixture at a temperature of 15O ⁰ C / 20 mbar for 45 minutes and determining the resulting weight loss (initial weight - final weight) according to the formula:

Percentage of low boiling components in weight percent = (weight loss / original weight) x 100.

Step c)

Step c) of the process according to the invention involves the addition of at least one reactive silane ii), without the addition of water and optionally the

Heating the resulting mixture. The addition of the reactive silane ii) after the Separation of the low-boiling constituents in step b) is expediently carried out after adjustment of such pressure and temperature conditions under which the contact time between the reactive silane ii) and the pretreated oxidic filler permits adequate reaction of the two components.

The admixing of the reactive silane (ii) can be carried out, for example, at a temperature of from room temperature to 150 ^° C., preferably under atmospheric pressure. The addition preferably takes place at room temperature.

After the addition of the reactive silane, the temperature may optionally be increased as long as one of the silanes remains in the mixture for a certain time or remains in contact with the pretreated oxidic filler.

The contact time after addition should expediently be at least about 30 minutes. The contact time depends on the contact temperature, the reactivity of the silanes ii) and their concentration in the mixture. The contact time may preferably be up to 2 days, in particular if the contact takes place at room temperature. In principle, it is possible to leave the filler after treatment with the silane ii) without further separation operation and use. However, it is recommended that in a further step, which in principle corresponds to step b), even after step c) remaining in the mixture low-boiling components such as excess silane ii) and reaction product thereof after a certain exposure time of 30 minutes to several days ( more than 1) from the mixture. The conditions of this further separation step can essentially correspond to the conditions of step b). If appropriate, steps b) and c) can be repeated once or several times.

The reactive silanes ii) of step c) may be the same or different than the reactive silanes used in step a). Preference is given in

Step c) uses the same reactive silanes as in step a). The reactive Silanes ii) of step c) are preferably selected from the group consisting of organosilazanes, hexaorganodisilazanes, trialkylsilylamines, trialkylsilyloximes or trialkylsilylamides. More preferably, the reactive silanes ii) are selected from hexaorganodisilazanes. Particularly preferred are hexamethyldisilazane and 1,3-divinyltetramethyldisilazane.

The amount of reactive silane ii) used in step c) is generally lower than the amount of reactive silane i) used in step a). The amount of reactive silane ii) used in step c) depends, for example, on the amount of reactive silane i) used in step a). In principle, the smaller the amount of the reactive silane i) used in step a), the greater must be the amount of the reactive silane ii) used in step c). To achieve sufficient modi fi cation of the filler in step c), less than about 15 parts by weight of the reactive silane ii) is suitably used per 100 parts by weight of the oxidic filler, more preferably less than about 3 parts by weight of the reactive silane ii). An amount less than 0.1 parts by weight of the reactive silane ii) per 100 parts by weight of the oxide filler is generally less preferred because the amount can not sufficiently reliably interact with the surface of the oxide filler.

Step c) is carried out without the addition of water. In fact, it has been found that the addition of water, as carried out in step a), in step c) surprisingly results in insufficient reduction of the intrinsic viscosity in the composition with the polymers.

By the method according to the invention oxidic fillers are produced, which cause less thickening than the hydrohobierten according to the previous methods of the prior art fillers effect at the same starting surface. Surprisingly, the use of large amounts of reactive silanes in a single-stage modification process does not lead to such a thickening behavior or degree of surface modification, as according to the invention two- or multi-stage modification process is achieved. Without wishing to be bound by theory, it is assumed that the surface of the oxidic filler becomes accessible for complete reaction with the reactive silane only by the intermediate separation of the low-boiling components in step b), or that this reaction takes place because of suitable conditions.

In order to be able to evaluate the quality of the modification as unambiguously as possible, the thickening effect occurring with the aid of polyethers was chosen as the benchmark for the completeness of the modification. At the same time, it is desirable to be able to produce such a polyether-containing composition without having to accept the known thickening effect.

In practice, the thickening effect in the presence of polyether as a surfactant for the hydrophilization of the surface of polymer moldings, an extremely sensitive probe for the degree of surface modification of the oxidic Füll¬ used materials. The obtained by the novel modified oxidic fillers lead even in the presence of Polyethem in the Einarbei¬ tion in polymers or crosslinking systems, especially in polysiloxane only to a small thickening effect. In contrast, the incorporation of surface-modified oxidic fillers prepared by conventional single-stage processes leads to a high intrinsic viscosity of the polymer compositions to be processed.

The invention thus relates not only to the fillers prepared by the process according to the invention, but also to compositions which comprise the filler according to the invention and at least one polymer or a crosslinkable composition. Preferred polymers or crosslinkable compositions into which the fillers prepared according to the invention can be incorporated include, for example, reactive resins such as epoxies, polyesters and coating compositions, and in particular polyorganosiloxanes. If the preparation of the filler according to the invention does not occur in the presence of the filler the polymer or the curable composition to be reinforced, the filler according to the invention for preparing the composition according to the invention in at least one polymer or in a curable composition or at least a single component thereof in the usual manner with conventional mixing equipment is incorporated, such as kneader , Dissolvers, mixers, such as screw mixers.

The modified filler produced according to the invention can be used in silicone rubber compositions, a preferred composition using the modified oxidic filler containing the following constituents:

(A) At least one polyorganosiloxane having at least two unsaturated

Groups per molecule, (B) at least one polyorganosiloxane having at least 2 SiH groups per molecule,

(C) 0.01 to about 70 parts by weight of the oxide filler modified according to the invention,

(D) at least one hydrosilylation-promoting catalyst selected from the group of compounds or metals containing at least one element selected from Pt, Ru, Rh, Ni, Ir, Ru and Pd,

(E) optionally one or more inhibitors which delay the hydrosilylation reaction,

(F) optionally one or more surfactants or other excipients.

In the inventively used silicone rubber compositions having the alkenyl group-containing polyorganosiloxane (A) preferably has a viscosity range from 0.025 to 500 Pa.s, preferably from 0.1 to 200 Pa.s (25 ⁰ C; Schergeschwin- digkeitsgefälle D of 1 s ^"1). It may consist of a uniform polymer or mixtures of different polyorganosiloxanes, such as different polymers (A1) or mixtures of the substantially linear polymers (A1) and linear or branched polymers (A2), as described in more detail below, consist.

The polyorganosiloxane (A) is preferably at least of the siloxane units are selected from the group consisting of the units M = R ¹ R ₂ SIOI _Z2, D = R ¹ RSi0 _2/2, T = R ¹ Si0 _3/2, Q = SiO _4/2, and the divalent units R ² where R, R ¹ and R ² are as defined below.

According to the invention, the polyorganosiloxanes (A) can in principle be selected from two groups (A1) and (A2).

The group (A1) represents the group of polyorganosiloxanes having a low alkenyl group content of about 0.002 to about 3.0 mmol / g, more preferably between 0.004 to 1.5 mmol / g. These polyorganosiloxanes are generally substantially linear ,

Group (A2) represents the group of polyorganosiloxanes having a high alkenyl group content of about 3.0 to about 22 mmol / g. These may include both linear and branched polyorganosiloxanes.

The polyorganosiloxanes (A) are preferably prepared by catalytic equilibration or catalyzed polycondensation, as described in US Pat. No. 6,387,487, column 3 u. 4 discloses. The polyorganosiloxanes (A) can be described by the general formula (I):

[M _a iDbiT _c1 QdiR ² ei] m1 (I)

wherein

T = R ¹ SiO ₃ Z ₂ , Q = SiO 2, in which

R = an optionally substituted organic group, preferably unsubstituted or substituted saturated hydrocarbon radicals, more preferably n-, iso-, tert- or C _r C ₂ alkyl, ₍₂ Ci-Ci) alkyl Ci-C ₂ alkoxy, C ₅ - C ₃₀ -cycloalkyl or C ₆ -C ₃ o-aryl, CrCl ₂ - alkyl (C ₆ -Cio) aryl, where these radicals R can optionally be substituted in each case by one or more F atoms and / or one or more -O Groups may contain.

Examples of suitable monovalent hydrocarbon radicals R include alkyl groups, preferably CH ₃ , CH ₃ CH ₂ , (CH ₃ ) ₂ CH, CsHi ₇ and CioH ₂ i groups, cycloaliphatic groups, such as cyclohexylethyl, aryl groups, such as phenyl, ToIyI, XyIyI, aralkyl groups such as benzyl and 2-phenylethyl groups. Preferred monovalent halohydrocarbon radicals R have in particular the formula C _n F _2n + iCH ₂ CH ₂ - where n has a value of 1 to 10, such as, for example, CF ₃ CH ₂ CH ₂ -, C ₄ FgCH ₂ CH ₂ - and C ₆ Fi ₃ CH ₂ CH ₂ -. A preferred radical is the 3,3,3-trifluoropropyl group. Particularly preferred radicals R include methyl, phenyl and 3,3,3-trifluoropropyl.

R ¹ = R or an unsubstituted or substituted C ₂ -C ₂ -alkenyl, which are preferably selected with the proviso that at least two radicals R ¹ are an alkenyl-containing organic group consisting of: unsubstituted and substituted alkenyl-containing hydrocarbon radicals, such as n-, iso -, tert - or cyclic C ₂ -C ₂ alkenyl, vinyl, allyl, hexenyl, C ₆ -C ₃₀ -cycloalkenyl, cycloalkenylalkyl, norbornenylethyl, limonenyl, C ₈ -C ₃ o-alkenylaryl, wherein optionally one or several - O atoms may be present (corresponding to ether residues) and which may be substituted by one or more F atoms. Preferred radicals R ¹ are groups such as vinyl, allyl, 5-hexenyl, cyclohexenylethyl, limonenyl, norbomenylethyl, ethylidene norbornyl and styryl, particularly preferably vinyl.

R ² = a divalent aliphatic n-, iso-, tert- or cyclic d-Ci ₄ alkylene radical, or a Cβ-Cu-arylene or Alkylenarylrest is, in each case two siloxy units M, D or T bridged, R ² , as defined in formula (I), bridges two siloxy units M, D or T. In each case, the divalent units R ² bridge two siloxane units, for example -DR ² -D-. In this case, R ^{2 is} preferably selected from divalent aliphatic or aromatic n-, iso-, tert- or cyclic C ₁ -C ₁₄ -alkylene, C ₆ -C ₄ -arylene or -Alkylenarylgruppen.

Examples of suitable divalent hydrocarbon groups R ² which can bridge siloxy units include all alkylene and dialkylarylene radicals, preferably those such as -CH ₂ -, -CH ₂ CH ₂ -, CH ₂ (CH ₃ ) CH-, - (CH ₂ ) ₄ , -CH ₂ CH (CH ₃ ) CH ₂ -, - (CH ₂ ) ₆ - - (CH ₂ ) ₈ - and - (CH ₂ ) i ₈ -cycloalkylene groups such as cyclohexylene, arylene groups such as phenylene, xylene. Their proportion generally does not exceed 30 mol% of all siloxy units. Preferred are groups such as alpha.omega-ethylene, alpha.omega-hexylene or alpha.omega-phenylene.

With

m1 = 1 -1000

a1 = 1 -10

b1 = 0-3000

d = 0-50

d1 = 0 - 1

e1 = 0-300.

Therein, the siloxy units M, D, T and Q can be distributed in blocks or randomly in the polymer chain and linked together. Within the polysiloxane chain, each siloxane unit may be the same or different.

The indices represent average degrees of polymerization. The indices are preferably as follows and are expediently chosen in accordance with the desired viscosity. The aforementioned polyorganosiloxanes (A1) preferably have a structure of the general formula (Ia)

R ¹ R ₂ Si0 (R ¹ RSiO) _b iSiR ₂ R ¹ (Ia),

preferably of the formula (Ia ')

R ¹ R ₂ SiO (R ₂ SiO) biSiR ₂ R ¹ (Ia ')

wherein R and R ^{1 are} as defined above and b1 <3000.

The polyorganosiloxanes (A1) of the formulas (Ia) and (Ia ') are substantially linear and have a content of unsaturated organic groups which is preferably between 0.002 to 3.0, more preferably between 0.004 to 1.5 mmol / g. The content of unsaturated organic groups refers to polymethylvinyl siloxane and must be adjusted accordingly within the given viscosity limits to siloxy groups with other substituents having different molecular weights.

The term "substantially linear" for the polyorganosiloxanes (A1), preferably includes such polyorganosiloxanes preferably not more than 0.1 mol% contain siloxane units of the T = RSiθ _3/2 or Q = SiO _4/2 Preferred siloxy units in the polyorganosiloxanes (A) are, for example, alkenylsiloxy units, such as dimethylvinylsiloxy, alkylsiloxy units, such as trimethylsiloxy, dimethylsiloxy and methylsiloxy units, arylsiloxy units, such as phenylsiloxy units, such as triphenylsiloxy-dimethylphenylsiloxy, diphenylsiloxy In the stated polyorganosiloxanes (A1), the radical R is preferably present as the methyl radical with at least 90 mol% (preferably 90 to 99.99 mol% relative to Si atoms). The alkenyl groups may be attached either at the chain end of a silioxane molecule or as a substituent on a silicon atom in a siloxane chain. In the case of alkenyl-poor, substantially linear polyorganosiloxanes (A1), the alkenyl groups are preferably present only at the chain end of the siloxane molecule. If alkenyl groups are present on internal silicon atoms of the siloxane chains, their content in the case of the alkenyl-poor polyorganosiloxanes (A1) is therefore preferably less than 0.01 mmol / g or less than 0.0074 mol%, based on siloxane units.

In order to improve the mechanical properties, such as the tear propagation resistance of the crosslinked products, blends of different polymers (ie there are at least two polymers (A1) or at least one polymer (A1) and (A2)) with different alkenyl content and / or used different chain length, wherein the total content of unsaturated groups 3.0 mmol / g in the component (A) based on vinyl-containing polydimethylsiloxanes expediently does not exceed. For example, mixtures of polyorganosiloxanes (A1) and (A2) in mixing ratios of

60 to 100 wt .-% (A1) and 0 to 40 wt .-% (A2) can be used. Both the polyorganosiloxane (A1) and the mixture of (A1) and (A2) preferably have a viscosity of 0.025 to 500 Pa.s, very particularly preferably 0.2 to 100 Pa.s at 25 ⁰ C. The viscosity is measured according to DIN 53019 at 25 ⁰ C and a shear velocity gradient D = 1 ^{s' 1.}

Preferably, the polyorganosiloxane (A1) has a number of siloxy units from 20 to 3000, particularly preferably 100 to 1500 (average degree of polymerization P _n , which refers to polymethylvinylsiloxane and adjust within the predetermined viscosity limits on siloxy groups with other substituents with different molecular weights accordingly is.) The alkenyl content is determined here by ¹ H-NMR - see AL Smith (ed.): The Analytical Chemistry of Silicones, J. Wiley & Sons 1991 Vol. 112 p. 356 ff. In Chemical Analysis ed. By JD Winefordner.

A further class of preferred polymers (A) which together with (A1) can form the component (A) are vinyl-rich, optionally branched polyorganosiloxanes (A2) which, for the purpose of enhancing e.g. the tear strength or tensile strength in combination with other polyorganosiloxanes, such as those defined above, can be used.

These branched alkenyl-rich polyorganosiloxanes (A2) are z. Example, in US 3,284,406, US 3,699,073 disclosed and contain a higher proportion of unsaturated radicals R ^1, preferably have, in contrast to the linear polyorganosiloxanes an increased proportion of branched or branching siloxane units T = RSiθ _3/2 or Q = SiO ^, which are present in one embodiment to more than 0.1 mol%, based on the Si atoms present. However, the amount of branching units should be limited by the fact that this component should preferably be liquid, low-melting (mp <16O ⁰ C) or with the other polymers (A1) miscible, transparent silicone compositions (> 70% transmission at 400 nm and 2 mm layer thickness).

The above-mentioned branched polyorganosiloxanes (A2) are polymers containing the aforementioned M, D, T and Q units. They preferably have the general formula (II), (IIa) to (IIb):

{[Risio _3/2] [R ⁴ Oi _{/ 2]}} ni m2 (IIa)

_{[SiO4 / _2}] [R ⁴ Oi _{/ 2]} ni [R ₂ R ¹ SIOI / _{2] o-io} .oi [RSiO _3/2] o-so [R ₂ SiO _2/2] 0-500W (Mb)

wherein R ^{4 is} a Ci to C ₂₂ organic radical, such as alkyl, aryl or arylalkyl. The radical R ⁴ Ov ₂ is preferably methoxy, ethoxy or hydroxy with the preferred indices m2 = 1 to 100 n1 = 0.001 to 4 a2 = 0.01 to 10 b2 = 0 to 10 c2 = 0 to 50 d2 = 1.

The molar ratio M: Q can assume values of 0.1 to 4: 1 or M: T of 0.1 to 3: 1, the ratio of D: Q or D: T of 0 to 333: 1, where the units M, D and T may contain the radicals R or R ¹ .

Alkenyl group-rich branched polyorganosiloxanes (A2) include in particular liquid polyorganosiloxanes, solid resins or liquid resins soluble in organic solvents, preferably consisting of trialkylsiloxy (M units) and silicate units (Q units), and preferably vinyldimethylsiloxy units in an amount of at least 3 mmol / g. These resins may also have up to a maximum of 10 mol% of alkoxy or OH groups on the Si atoms.

In another preferred embodiment, the polyorganosiloxanes (A2) have the general formula (Ia) with the proviso that they have an increased vinyl content as defined under (A2).

In the aforementioned branched polyorganosiloxanes (A2), the radical R is preferably present as the methyl radical with at least 50 mol% (i.e., 50 to 95 mol% with respect to Si atoms), preferably at least 80 mol%. The alkenyl-rich, preferably vinyl group-rich, polyorganosiloxane (A2) preferably has an alkenyl group content of more than 3 mmol / g to about 22 mmol / g, which relates to polymethylvinyl siloxanes and within the prescribed viscosity limits siloxy groups with other substituents on the silicon atom with a different molecular weight is to be adjusted accordingly.

In a preferred embodiment of the invention, the polyorganosiloxane (A) comprises substantially vinyl-poor linear polyorganosiloxanes (A1) as above described. Vinyl-rich polyorganosiloxanes (A2) as described above can be added to improve mechanical properties, especially when the amount of filler is limited, for example, for reasons of viscosity. Another preferred blend of the polyorganosiloxanes (A) contains at least two substantially linear alkenylene end-stopped polyorganosiloxanes (A1) having different alkenyl, preferably vinyl, contents. By means of this measure, on the one hand, the lowest possible viscosity of the silicone composition should be prescribed, on the other hand, a crosslinking structure with the Si-H compounds of component (B) defined below be made possible, which effects the highest possible mechanical strengths, such as elongation and tear propagation resistance of the crosslinked silicone rubbers. If larger amounts of short-chain alpha-omega-vinylsiloxanes (conveniently below a viscosity of 10 Pa.s) are used, this requires larger amounts of alpha, omega-Si-H-siloxanes as chain extenders to form suitable crosslinking structures.

An alkenyl group-containing, which does not consist of a mixture of a polydiorganosiloxane of the type (A), is defined by the fact that the distribution of the weight and number average from one of the known polymerization reactions, preferably from the equilibration or polycondensation with basic or acid catalysts. Such processes with alkaline or acidic catalysts are disclosed, for example, in US Pat. No. 5,536,803, column 4. Polyorganosiloxanes equilibrated by this method usually have a ratio Mw / Mn of 1 to 10, preferably 1-2, without taking into account the proportions with a molecular weight of less than 500 g / mol for the case R = methyl and R ¹ = vinyl.

For the polymerization reaction with basic or acidic catalysts, it is possible to use both the various cyclosiloxanes, linear polyorganosiloxanes and also symmetrical 1,3-divinyltetramethyldisiloxane, other long-chain siloxanes having a trialkylsiloxy end stop or OH end groups. By way of example, the hydrolysates of different alkylchlorosilanes are used for this purpose. such as vinyldimethylchlorosilane and / or dimethyldichlorosilane and the trialkyl-terminated siloxanes obtained therefrom by themselves or in a mixture with other siloxanes.

The average degree of polymerization P _{n of} the polyorganosiloxanes (A), measured as number average M _n by GPC and with polystyrene as standard, is preferably in the range of P _n > 20 to 3000, the more preferred range is P _n 200 to 1500.

The polymers (A) defined herewith, in combination with suitable polyhydrogenorganosiloxanes of component (B) described below, permit the preparation of flowable casting compositions which have sufficiently good rubber-mechanical properties, such as elongation at break, tensile strength and tear resistance, and stability of the mechanical properties.

Component (B) (Si-H-containing polysiloxanes)

The polyorganohydrogensiloxanes (B) are preferably selected from linear, cyclic or branched SiH-containing polyorganosiloxanes of the general formula (II):

wherein

D = R ³ RSiO ₂ Z ₂ ,

T = R ³ SiO ₃ Z ₂ ,

Q = SiO ₄ z 2, in which

R = n-, iso-, tert- or CrCl ₂ alkyl, _Ci-Ci2 alkoxy (CrCl ₂₎ alkyl, C ₅ -C ₃₀ cycloalkyl, or Cβ-Cso-aryl, CrCl ₂ alkyl (C ₆ -C) aryl, where these radicals R may be optionally substituted by one or more F atoms and / or may contain one or more -O-groups, R ³ = R or hydrogen, with the proviso that at least two R ^{3 groups} per molecule are hydrogen, both of which may occur simultaneously in one molecule, but at least two R ^{3 groups} per molecule are hydrogen, R is defined above, is preferred R = methyl. R ² = a divalent aliphatic n-, iso-, tert-, or cyclic CRCI ₄ alkylene radical, or a Cβ-C _M arylene or alkylenearyl radical, the bridging two siloxy units M, D or T,

m3 = 1 to 1000

a4 = 1 to 10

b4 = 0 to 1000

c4 = 0 to 50

d4 = 0 to 1

e2 = 0 to 300.

Polyorganohydrogensiloxanes (B) are preferably linear, cyclic or branched polyorganosiloxanes whose siloxy units are advantageously selected from M = R ₃ Si0i / _2, M ^H = R ₂ HSiOi / _2, D = R ₂ Si0 _2/2, D ^H = RHSi0 _2/2, T = RSiO _3/2, T ^H = HSiθ _3/2, Q = SiO _4/2 in which these units are preferably from MeHSiO or Me ₂ HSiOo, ₅ units, optionally together with other organosiloxy units, preferably vor¬ Dimethylsiloxy units. The siloxy units can be present in blocks or randomly linked to one another in the polymer chain. Each siloxane unit of the polysiloxane chain may carry identical or different radicals.

The indices of the formula (III) describe the average degree of polymerization Pn measured as the number average Mn, determined by GPC (polystyrene as standard), which relate to polyhydrogenmethylsiloxane and are adapted within the given viscosity limits to siloxy groups having different substituents and different molecular weights. The polyorganohydrogensiloxane (B) comprises, in particular, all the liquid, flowable and solid polymer structures of the formula (III) having the degrees of polymerization resulting from the abovementioned indices. Preference is given to the low molecular weight polyorganohydrogensiloxanes (B) which are liquid at 25 ^° C., ie less than about 60,000 g / mol, preferably less than 20,000 g / mol.

The preferred polyorganohydrogensiloxanes (B) are structures selected from the group which can be described by the formulas (IIIa-IIIe)

HR ₂ Si0 (R ₂ Si0) _z (RHSiO) p SiR ₂ H (MIa) HMe ₂ SiO (Me ₂ SiO) _Z (MeHSiO) _P SiMe ₂ H (MIb)

Me ₃ SiO (Me ₂ SiO) _z (MeHSiO) p SiMe ₃ (MIc)

Me ₃ SiO (MeHSiO) _p SiMe ₃ (MId)

{[R ₂ R ³ SiOi / ₂ ] _0-3 [R ³ SiO _3/2 ] [R ⁴ O] ₁₁₂ Jm ₃ (MIe)

{[SiO _4/2}] [R ⁴ Oi / _2] n ₂ [R ₂ R ³ SIOI / _2] o, oi-io [R ³ SiO _3/2] o o _-5 [RR ³ SiO _2/2] 0-1000} m ₃ (MIf) with z = 0 to 1000 p = 0 to 100 z + p = b4 = 1 to 1000 n ₂ = 0.001 to 4 where R ⁴ Ov _{2 is} an alkoxy radical on the silicon,

R ³ as defined above.

A preferred embodiment of the class of compounds (MIe) and (MIf) are, for example, monomeric to polymeric compounds which can be described by the formula [(Me ₂ HSiO) 4Si] _m3 . The SiH concentration is preferably in the range of 0.1 to 17 mmol / g, which relates to polyhydrogenmethylsiloxanes and is to be adapted within the given viscosity limits to siloxy groups with other substituents.

In a particularly preferred selection of formula (MIb) where R = methyl and z> 0, the polymeric crosslinkers have a preferred SiH concentration 0.05 to 12 mmol SiH / g. If z = O, as in formula (MIc) where R = methyl, the SiH concentration is preferably 7-17 mmol SiH / g.

In a preferred embodiment of the invention, the polyorganohydrogensiloxane (B) consists of at least one polyorganohydrogensiloxane (B1) having two Si-H groups per molecule and at least one polyorganohydrogensiloxane of the type (B2) having more than two Si-H groups per molecule , In this embodiment, component (B) consists of at least two different organohydrogenpolysiloxanes which produce different crosslinking structures to give, in conjunction with low viscosity polysiloxanes of component (A), silicone elastomers of high strength. These different organo hydrogenpolysiloxanes can be assigned essentially two functions. Bifunctional polyorganohydrogensiloxanes (B1) act as chain extenders, while the polyorganohydrogensiloxanes (B2) of higher functionality (> 2) act as crosslinkers. The silicone composition used according to the invention preferably contains at least one bifunctional chain extender (B1) and at least one crosslinker (B2).

Examples of preferred structures of component (B1) in the silicone rubber composition of the invention include the chain extenders (B1) such as:

HMe ₂ SiO- (Me ₂ SiO) _Z SiMe ₂ H and

Me ₃ SiO- (Me ₂ SiO) _z (MeHSiO) ₂ SiMe ₃ ,

[(Me ₂ SiO) z (MeHSiO) ₂ ]

The crosslinkers (B2) contain compounds such as:

Me ₃ SiO- (MeHSiO) _p SiMe ₃ ,

HMe ₂ SiO (Me ₂ SiO) _z (MePhSiO) _z (MeHSiO) _p SiMe ₂ H,

(MeHSiO) p, (HMe ₂ SiO) ₄ Si

MeSi (OSiMe ₂ H) ₃ wherein p, z are as defined above.

Such mixtures of so-called chain extenders and crosslinkers can be used, for example, as described in US Pat. No. 3,697,473. In a further preferred embodiment, the amount of the components (B1) and (B2) is

0 to 70 mol% (B1)

30 to 100 mol% (B2) based on (B1) and (B2).

If an increase in the crosslinking rate is necessary, this can be achieved, for example, by increasing the ratio SiH to alkenyl, an increased amount of catalyst (d) or by increasing the proportion of polyorganosiloxanes (B2) which contain HMe ₂ SiO ₂ , ₅ units. be achieved.

The polyorganosiloxanes (B) are preferably liquid at room temperature or siloxanlöslich, ie they preferably have less than 1000 siloxy units on, ie they preferably have viscosities below 40 Pa.s at 25 ⁰ C and D = 1 ^{s' 1.}

The chain length of the crosslinkers as component (B2), which consist predominantly of MeHSiO units, is preferably from 3 to 200, more preferably from 15 to 60 MeHSiO units.

The chain length of the chain extenders as component (B1), which consist predominantly of Mβ2SiO units and HMβ2SiOi _/ 2, is preferably from 2 to 100, more preferably from 2 to 60 Me ₂ SiO units.

The SiH content is determined in the present invention by ¹ H-NMR see AL Smith (Ed.): The Analytical Chemistry of Silicones, J. Wiley & Sons 1991 Vol. 12 p. 356 et seq. In Chemical Analysis ed. By JD Winefordner. The polyorganohydrogensiloxanes (B) can be prepared by methods known per se, for example by acidic equilibration or condensation, as disclosed, for example, in US Pat. No. 5,536,803. The polyorganohydrogensiloxanes (B) can also be reaction products which have arisen from a hydrosilylation of organohydrogensiloxanes with alkenyl-containing siloxanes in the presence of the catalysts (c), the resulting SiH content preferably being within the previously defined limits. This results in R ² - or alkylene-bridged organohydrogensiloxanes (B).

The polyorganohydrogensiloxanes (B) may also be reaction products resulting from the condensation of e.g. Organohydrogenalkoxysiloxanen (B) with hydroxy or alkoxysilanes or siloxanes have emerged, such. in US 4 082 726 e.g. Columns 5 and 6 described.

According to the invention, the ratio of component (B) to component (A) is preferably chosen such that a molar ratio of Si-H to Si-alkenyl units of about 0.5 to 20: 1, preferably from 1 to 3: 1 is present ,

The preferred amount of the polyorganohydrogensiloxanes (B) is 0.1 to 200 parts by weight based on 100 parts by weight of the component (A).

Many properties, such as the rubber-mechanical properties, the rate of crosslinking, the stability and the stability to hot air, can be influenced by the ratio of SiH to Si alkenyl units.

The component (D), the hydrosilylation catalyst, preferably contains at least one metal selected from the group consisting of Pt, Pd, Rh, Ni, Ir or Ru. The hydrosilylation catalyst can be used in metallic form, in the form of a complex compound and / or as a salt. The catalysts can be used with or without support materials in colloidal or powdered state. The amount of component (D) is preferably 0.1-5000 ppm, preferably 0.5-1000 ppm, more preferably 1-500 ppm, more preferably 2-100 ppm, calculated as metal, based on the weight of the components (A ) to (C) + (F).

In the group of Pt, Rh, Ir, Pd, Ni and Ru compounds, i. their salts, complexes or metals, the component (D), for example, from the Pt catalysts, in particular Pt ° complex compounds with olefins, more preferably with vinylsiloxanes, such as complexes with 1, 3-divinyltetra methyldisiloxane and / or tetravinyltetramethyltetracyclosiloxane ,

These Pt catalysts are exemplified in US 3,715,334 or US 3 419 593 and Lewis, Colborn, Grade, Bryant, Sumpter and Scott in Organometallics, 1995, 14, 2202-2213.

The preferred Pt ° olefin complexes are prepared in the presence of 1,3-diaminotetamethyldisiloxane (M ^{V |} ₂ ) by reduction of hexachloroplatinic acid or of other platinum chlorides. As a rule, these platinum catalysts contain, in addition to the vinyl siloxanes bound to platinum, free, non-complexed vinyl siloxanes. It may be diluted with vinyl-terminated polydimethylsiloxanes (A) to a platinum concentration of about 0.5 to 2% by weight before use for better dosage.

Likewise, of course, other platinum compounds, as far as they allow rapid crosslinking, can be used, such as the photoactivatable Pt catalysts of EP 122008, EP 146307 or US 2003-0199603.

The rate of hydrosilylation is determined by the selected catalyst compound, its amount, and the type and amount of additional inhibitor component (E).

The amounts of catalyst are limited by the costs incurred upwards and the reliable catalytic effect down. Therefore are Amounts above 100 ppm metal mostly uneconomical, amounts below 1 ppm unreliable.

As carriers for the catalysts, all solids can be selected as long as they do not undesirably inhibit hydrosilylation. The carriers can be selected from the group of powdered silicic acids or gels or organic resins or polymers and are used in accordance with the desired transparency; preference is given to non-opacifying carriers.

The surface-modified oxidic fillers obtained by the process according to the invention are preferably added to the compositions according to the invention in amounts of about 0.001 to about 70 parts by weight per 100 parts by weight of the polymers or of the crosslinkable compositions (crosslinkable polymer and crosslinker). More preferred are about 1 to about 50, more preferably 5 to 40 parts by weight of the modified oxidic filler per 100 parts by weight of the polymers or crosslinkable compositions. If appropriate, the composition according to the invention may contain one or more further fillers which are not surface-treated by the process according to the invention, as long as the solution of the problem according to the invention is not impaired. These may be, in particular, surface-poor fillers having BET surface areas of less than about 10 m ² / g.

The reaction rate can be reduced, if appropriate, by addition of inhibitors (E), such as vinylsiloxanes, 1,3-divinyltetramethyldisiloxane or tetravinyltetramethyltetracyclosiloxane, at concentrations above 30 ppm of platinum. Other known inhibitors can also be used, for example ethynylcyclohexanol, 3-methylbutynol or dimethyl maleate.

The composition of the invention may further optionally contain one or more hydrosilylation reaction retarding inhibitors (E). They serve to delay the crosslinking reaction at room temperature for a certain time. Thus, at temperatures from 0 to 3O ⁰ C both a time-limited Inhibition (pot life) as well as a sufficiently fast and complete wettability (to the extent of free of charge) at elevated temperature.

In principle, all known for the class of the group of platinum metals

Inhibitors are used, if not enough already by selecting the ligands of the catalyst (D) a sufficiently long processing time is achieved. A preferred embodiment is the catalyst with at least one inhibitor

(E) use.

Examples of the variety of known inhibitors are unsaturated organic

Compounds such as ethylenically unsaturated amides (US 4,337,332); acetylenic compounds (US 3 445 420, US 4 347 346), isocyanates (US 3 882 083); unsaturated siloxanes, (US 3,989,667); unsaturated diesters (US 4,256,870, US 4

476,166 and US 4,562,096), hydroperoxides (US 4,061,609), ketones (US 3,418,731);

Sulfoxides, amines, phosphines, phosphites, nitriles (US 3,344,111), diaziridines (US 4

043 977). The best known class of inhibitors are the alkynols as described in US 3,445,420. These are e.g. Ethinylcyclohexanol and 3-methylbutynol and the unsaturated carboxylic acid esters of US Pat. No. 4,256,870 as well as diallylmaleate and dimethyl maleate and the fumarates of US Pat. Nos. 4,562,096 and 4,774,111, such as diethyl fumarate,

Diallyl fumarate or bis (methoxyisopropyl) maleate. From the series of unsaturated carboxylic acid esters are preferred inhibitors

Maleates and fumarates of the general formula

R ^w (OW) _v O ₂ CCH = CHCO ₂ (WO) _v R ^w wherein:

R ^w is selected from the group of d-do alkyl radicals such as methyl, ethyl, propyl, isopropyl, butyl, etc., and aryl radicals such as phenyl or benzyl, an alkenyl radical such as

Vinyl or AIIyI,

W is independently selected from divalent C ₂ -C ₄ -alkylene radicals, the subscript V is 0 or 1.

The amount of the inhibitor component (E) is suitably chosen so that the desired crosslinking time under the selected processing conditions, in particular in coordination with the catalyst (D) and the other Components in a suitable manner, ie time and temperature can be adjusted. The amount of inhibitor component (E) is preferably from 0.0001 to 2% by weight of one or more inhibitors based on the total amount of components (A) to (C) + (F). When the inhibitor component (E) is used, more preferably about 0.001 to 0.5% by weight, more preferably 0.05 to 0.2% by weight, based on the total amount of the components (A) to (C) + (F) preferably alkynols at metal contents of component (D) of 10 to 100 ppm added. Preferably, component (E) is selected from the group consisting of alkynols and vinylsiloxanes.

The inventive compositions containing the filler according to the invention, in particular polyorganosiloxane compositions further ent contain optionally one or more auxiliaries (F), such as plasticizers or release oils, such as polydimethylsiloxane oils, without reactive alkenyl or SiH groups having a viscosity of preferably 0.001-10 Pa.s at 25 ⁰ C.

In a preferred embodiment, said composition contains at least one surfactant as auxiliary (F). Surfactant here means, in particular, a surface-active compound which in particular does not interfere with the hydrosilylation reaction, which, for example, enters into the system described above. Such surfactants include, for example, nonionic surfactants such as polyethers, polyesters, polyamides or copolymers of these types, as well as cationic surfactants, etc. These surfactants are used, in particular in the case of polyorganosiloxane compositions in which the fillers (C) prepared according to the invention are contained, to make the surface of the cured compositions wettable or to make them more hydrophilic or antistatic. Here are the compounds vor¬ geous, which segregate quickly and migrate to the surfaces. The auxiliaries mentioned, in particular the surfactants (F), are preferably present in the compositions according to the invention in an amount of about 0.1 to 20 parts by weight, based on 100 parts by weight of the polymers (A) + ( B) or the crosslinkable Contain compositions (crosslinkable polymer and crosslinker) and the filler.

According to the invention, the surface-active, hydrophilic-enhancing additives are understood to be all conceivable surface-active compounds, in particular nonionic ethoxylated surfactants which contain, in addition to polyalkene oxide units, further solubilizing units such as perfluoroalkyl radicals, polyorganosiloxane radicals, alkylsiloxy radicals, alkyl radicals, alkylaryl radicals, C r C ₃ o-fatty acid ester radicals , Fatty alcohol radicals or C 2 -C 20 -alkylphenolpolyether radicals may contain.

The surfactants include, for example, polyhydroxylated fatty alcohols, amides of polyethers or polyalcohols, polyhydroxylated fatty amines, polypropylene oxide compounds or polyethylene oxide compounds.

Furthermore, the surfactants also include polyether siloxanes, wherein the polyether group is selected from polyethylene oxide or polypropylene oxide and these

Polyether groups bound as an end or side group in a siloxane main chain bonded via SiC or SiOC.

In addition, as surface-active compounds it is also possible to use polyalcohols, such as alkylglucosides, alkylpolyglucosides, sugar esters, sugar esters, sugar glycerides, esters of sorbic acid.

The surface-active compounds can be present individually or as a mixture.

They may also include alkylbenzene sulfonates, alkyl sulfates, alkyl ether sulfates, and alkylaryl ether sulfates. Also suitable are alkyl succinates, the alkyl carboxylates, the derivatives of hydrolyzed proteins, alkyl phosphates, aryl phosphates, alkyl ether phosphates, if appropriate their alkali metal or alkaline earth metal salts or mixtures with the abovementioned surface-active agents.

The surface-active compounds may also include cationic surfactants such as trialkyl ammonium benzyl halides, tetraalkyl ammonium halides or mixtures thereof. In addition, surfactants such as alkyl betaines, alkyl dimethyl betaines, alkyl amidopropyl betaines, alkylamidopropyl dimethyl betaines are also suitable.

Surfactants also include alkyltrimethylsulfobetaines, derivatives of imidazolines, such as the alkylamphoacetates, alkylamphodiacetates, alkylamphopropionates, alkylamphodipropionates, alkyl sultans, alkylamidopropylhydroxysultes, condensation products of fatty acids, and hydrolyzates of proteins. Preference is given to the nonionic surfactants which have a particularly low influence on the hydrosilylation reaction during crosslinking to form elastomeric moldings or coatings. Within this group are

(Fa) the aliphatic ethers and esters of polyalkylene oxides having 2 to 25 alkoxy groups, in particular based on ethylene oxide and propylene oxide, which may preferably also contain unsaturated organic groups, such as allyl groups and

(Fb) Polyethersiloxane with ethylene and / or propylene oxide side groups, as described in US 4,657,959, preferred.

The surfactants (Fa) and (Fb) are preferably soluble in polyorganosiloxanes, ie there is no segregation, if 10 wt.% Polyether or polyether siloxane present in a polyorganosiloxane having a viscosity of 10 Pa.s at 25 ⁰ C. The surfactants (Fa) and (Fb) suitably contain one or more solubilizing groups which suppress this segregation.

The polyethersiloxanes (Fb) preferably also contain at least one unsaturated aliphatic or cycloaliphatic C 2 -C 10 -group, which together with SiH groups can be converted into SiC bonds in a hydrosilylation reaction.

The surfactants (FA) suitably contain as solubilizing groups, for example preferably one or more hydrocarbon or perfluoroalkyl groups, which render the surfactants soluble or dispersible in the crosslinking systems, in particular the polyorganosiloxanes. The surfactants (Fb) are useful as solubilizing groups additionally one or more polyorganosiloxane groups. In addition, (Fa) and (Fb) may contain hydrophilic groups which impart a hydrophilic surface to the crosslinked compositions of the invention. Ethoxylated surfactants which contain a hydrocarbon-matrix-solubilizing group, ie are fat-soluble, are described in "Surfactants and Detersive Systems", Kirk-Othmer Encyclopedia of Chemical Technology, 3rd Ed., 22, 360-377 (1983). Ethoxylated surfactants are furthermore described, for example, in US Pat. Nos. 3,505,377, 3,980,688 and 4,431,789. Furthermore, it is preferred that the polyethersiloxanes (Fb) themselves have a Pt-containing content of less than 1 ppm.

The surfactant must be present in a sufficient amount with a sufficient number of hydrophilic groups in order to be able to provide the surface of the polymer, such as that of the crosslinked silicone elastomer, with sufficient hydrophilicity. Thus, the preferred amount of the hydrophilic additive of the present invention will be in the range of 0.1 to 30 weight percent, more preferably 1 to 15 weight percent, most preferably 3 to 10 weight percent of the total composition.

Sufficient wettability is characterized in that the contact angle of the crosslinked silicone composition has a 3-minute value below 65 °.

The term ^' 3-minute contact angle ^' means a contact angle formed by a drop of distilled water applied after 3 minutes of crosslinking to a cured polymer, particularly silicone surface. It can be measured at 25 ^° C. with a goniometer (eg Model 100 from Rame-Hart, Ine, Mountain Lakes, NJ). The measuring method has been described in W. NoII, "Chemistry and Technology of Silicones" (1982) pp. 447-448. Preferably, a measurement is carried out in such a way that, in particular, the silicone composition is cured on a smooth surface, for example a glass or polished metal surface, and after the mold surface and crosslinked silicone elastomer have been separated, a drop of water is applied to the smooth, cured silicone topcoat. area brings. The compositions according to the invention preferably have a 3-minute value against water of below 45 °, more preferably of below 30 °, most preferably of below 10 °.

The size of the contact angle depends strongly on the amount of the surfactant on the surface of the polymer, such as the silicone elastomer. In general, the amount of surfactant on the surface increases with increasing amount of ethylene oxide units in the surfactant. The contact angle decreases to the same extent. The surfactants (F) which are preferably used according to the invention may in principle be those which have reactive groups which lead to incorporation into the polymeric siloxane network, or are those which have no reactive groups which they contain The surfactants which contain no reactive groups which make them capable of incorporation into the polymeric network can be, for example, the above-described surfactants, in particular non-reactive polyether compounds.

The surfactants which contain reactive groups which make them capable of incorporation into the polymeric network when using the hydrosilylation reaction may be, for example, those which contain reactive groups selected from hydroxyl groups, Si-alkenyl groups, alkenyloxy groups, such as Allyloxy, and Si-H groups. Thus, both the surfactants (Fa) and (Fb) may have reactive groups.

Of course, the choice of reactive groups depends on the nature of the reactive groups of the crosslinkable polymer system used. In principle, it can therefore be any desired functional group which can participate in the crosslinking of the crosslinkable polymer system. However, it may also be any other functional group capable of reacting with the crosslinking groups of the crosslinkable polymer system. These include, for example, OH groups which can form SiOC or SiOSi bonds, but also other organofunctional groups such as epoxy, halogen, amino groups, which can bond to the Si functionalized moieties on the Si, when in the polyanagnosiloxane composition, the crosslinking or vulcanization by hydrosilylation is initiated or the composition is heated to at least 6O ⁰ C. , As a result, in a preferred embodiment, these reactions lead to binding of the hydrophilizing surfactant to the polyorganosiloxanes.

For the inventively preferred curable polysiloxane compositions, which are preferably crosslinked by hydrosilylation reaction, come in particular alkenyl-containing surfactants, in particular polyether compounds in question, the terminal Alkenyl- bezw. Wear cycloalkeny groups.

Such alkenyl group-containing surfactants include, for example, the linear, cyclic or branched polysiloxane-polyether copolymers described in US Pat. No. 6,013,711, which are selected, for example, from the following formulas:

Linear: R ⁵ R ² SiO (SiR ₂ O) p- (SiR ⁶ ZO) _m -SiR ₂ R ⁵ (IV a)

R ⁵ R ₂ SiO (SiR ₂ O) p- (SiR ⁶ ZO) _m -SiR 3 (IV b)

R ₃ SiO (SiR ₂ O) _p - (SiR ⁶ ZO) _m - (SiR ⁶ R ⁵ O) _q -SiR ₃ (IV c)

R ⁵ R ₂ SiO (SiR ₂ O) p- (SiR ⁶ ZO) _m - (SiR ⁶ R ⁵ -O) _q -SiR ₃ (IV d)

R ⁵ R ₂ SiO (SiR ₂ O) p- (SiR ⁶ ZO) _m - (SiRR ⁵ -O) _q -SiR ₂ R ⁵ (IV e) Z-R ₂ SiO (SiR ₂ O) _p - (SiRR ⁵ -O) _q -SiR ₂ R ⁵ (IV f)

[Z-R ₂ SiO (SiR ₂ O) _p ] _r - (SiR ₂ -O) - (SiRR ⁵ -O) _q -SiR ₂ R ⁵ (IV g)

cyclic:

(R ₂ Si-O) p- (SiR ⁶ ZO) _m - (SiRR ⁵ -O) _q (IV h)

branched: R ⁵ Si [(O-SiR ₂ ) _P -Z] ₃ (IVi)

RSi [(O-SiRR ⁵ ) _q - (O-SiR ₂ ) _P -Z] ₃ (IVj)

[R ⁵ R ₂ SiO (SiR ₂ -O) _P ] v-Si [(O-SiRR ⁵ ) _q (O-SiR ₂ Z) _m ] ₄ . _v (IVk)

The values of the indices m, p, q, r and v in the formulas (IV) are preferably selected such that the total number of silicon atoms per molecule is 2 to 20, preferably 2 to 10, more preferably 2 to 5, inclusive in that there is at least one Z and at least one R ⁵ per molecule, v has the value 0 to 1; with 3>m> 0 and 0> q and p <3. R is as defined above.

More preferably, it is a vinyl end-stopped siloxane with p = 0. R is preferably methyl, particularly preferred is a trisiloxane.

R ⁵ is a CrC ₂₀ , preferably unsaturated, monovalent organic d-Ci ₂ group, which can be hydrosilylated with SiH groups and then forms a Silizium-Kohlenstoffbin fertil. Examples of the unsaturated groups which represent R ⁵ are alkenyl groups, for example the vinyl, allyl, methallyl, 5-hexenyl, vinylcyclohexyl, limonyl,

Nombomenyl, vinylphenylethylene, allylglycidyl and the alkynyl group e.g. the

Ethynyl and the propargyl group or chloropropyl, aminoalkyl and the epoxyalkyl group. Furthermore, R ⁵ may be phenyl or 3,3,3-trifluoropropyl.

R has the meaning as defined above and preferably represents a saturated, monovalent organic d-Ci ₂ group. The radical R can also be a functionalized organic group R ^f , such as the chloropropyl, Heptafluorisopropyl-, C ₆ Fi ₃ -ethylene , 3,3,3-trifluoropropylaminoalkyl, epoxyalkyl and cyanoethyl groups. Suitable ethoxylated surfactants containing perfluoroalkyl groups as solubilizing groups are described in US 2,915,544 or US 4,484,990.

Z is a polyether-containing group which preferably binds to a polyorganosiloxane block via a silicon-carbon bond. For example, Z has the general formula (Va): R '- (OC ₂ H ₃ R) χ (OC ₃ H ₆ ) _y R ² - (Va)

wherein R 'is R or hydrogen and R ^{2 are} as defined above and R' is preferably R ^f and x is an integer in the range 1-20, preferably 2-8 and y is an integer from 0 to 5. Examples of the oxyalkylene groups for the polyether part of one type of these copolymers are the oxyethylene, oxy-1,2-propylene, oxy-1,2-butylene, oxy-2,2-dimethyl-1,3-propylene group and like. The polyether portion of the copolymer may contain oxyalkylene units of one or more types. For the optimum of hydrophilicity, it is desirable that at least 40% by weight and preferably at least 50% by weight of the oxyalkylene or alkyleneoxy groups are ethyleneoxy groups. In the abovementioned surfactants of the formulas (Va), R ^{1 is} hydrogen or a linear or cyclic C 1 -C ₉ -alkyl or C 1 -C -acyl group or a vinyl, ether or organosilyl group.

The radicals R ^{1 which} are exemplary of alkyl groups are methyl, tert-butyl and 2-ethylhexyl. Examples of acyl end groups are acetoxy, acetoacetoxy, acryloxy, methacryloxy and benzoyl groups. Organosilyl end groups include the saturated trialkylsilyl groups such as trimethylsilyl, triethyl, ethylisopropyl, tert-hexyldimethyl, tert-butyldimethyl, tert-butyldiphenyl; the unsaturated end groups include groups such as vinyldimethyl, divinyloctyl, ethynyldimethyl and Propynyldimethyl groups. Examples of vinyl ether end groups include dihydropyranyl and vinyloxyethoxy (H ₂ C = CH-O-CH ₂ CH ₂ O-). In accordance with the different efficacy of the polyether end-stop reaction, OH-terminated polyether molecules are often present as starting material during the synthesis of the polysiloxane-polyether copolymers. Similarly, nominally terminated copolymer products may also contain non-terminated polysiloxane polyether copolymers.

Specific examples of the structures according to the invention are: H ₂ C =CH-P- (CH ₃ ) ₂ SiO - [(CH ₃ ) ₂ SiO] o _-2 - [CH ₃ ZSiO] i _-5 -Si (CH ₃ ) ₂ - P-CH = CH ₂ (VI a)

P = -cyclo-alkylene or a bond, H2C = CH (CH3) 2 SiO - [(CH3) 2SiO] o-2- [CH ₃ ZSiO] i-5-Si (CH3) 2 CH = CH ₂ (VI b)

H2C = CHSi (CH3) 2-0- [Si (CH3) 2-0] o-2 [Si (CH 3) Z-0] i-5-Si _(CH3) 2CH = CH2 (VIc)

H ₂ C = CHSi (CH 3) 2 -O-Si (CH 3) ZO-Si (CH 3) ₂ CH = CH ₂ , (VId)

H ₂ C = CHSi (CH ₃ ) 2 -O-Si (CH ₃ ) ZO-Si (CH ₃ ) ₂ CH = CH ₂ , (VIe) H ₂ C = CHSi (CH ₃ ) 2 -O-Si (CH ₃ ) ZO-Si (CH 3) 2 CH = CH ₂ (VIf)

H ₂ C = CHSi (CH ₃ ) 2 -O- [Si (CH ₃ ) 2 O] 2 - [Si (CH ₃ ) ZO] -Si (CH ₃ ) ₂ CH = CH ₂ (VIg)

H ₂ C = CHSi (CH ₃ ) ₂ -O- [Si (CH ₃ ) ₂ O] - [Si (CH ₃ ) ZO] ₂ -Si (CH ₃ ) ₂ CH = CH ₂ (VIh)

wherein Z is as defined above and is preferably Z1 with

Z1 = - (CH ₂ J ₃ O (C ₂ H ₄ O) I _-20 R 'and R' = H, C 1 -C 18 -alkyl, - (CH ₂ ) ₃ O (C ₂ H ₄ O) 7, ₅ CH ₃ , - (CH ₂ J ₃ O (C ₂ H ₄ O) ₅ (C ₃ H ₆ O) ₂ H, or - (CH ₂ J ₃ O (C ₂ H ₄ O) ₃ CH ₃ ,

In the preferred class of ethoxylated surfactants containing the group which increases solubility in polyorganosiloxanes of formulas (A) and (B), x is selected to be sufficiently large and y is selected to be sufficiently small to achieve the desired 3 minute value for to achieve the water contact angle. The polyethers may be random or block-structured polymers of different alkylene oxides. However, it is preferable to construct polyether units of essentially ethyleneoxy and propyleneoxy units, of which in turn the block copolymers are preferred in the presence of C2 and C3 units. In particular, however, it is preferred that the polyether has only ethylene oxide units with C1-Cig-alkyl end groups.

Some of the above polyether siloxanes are commercially available from General Electric Silicones under the name SILWET®. Preferred SILWET surfactant types are copolymers such as SILWET L-77, L-7600 and L-7602.

Another class of polyethers (Fb) may be polyether siloxanes in which the polyether radical Z as Z 2 via -O- to Si of the formulas (IV) and (VI) binds with: Z ₂ = -O (C ₂ H ₄ O) I _-20 R 'wherein R' = C 1 -C 9 -alkyl, -O (C ₂ H ₄ ) ₇ , 5ORO-O (C ₂ H ₄ O) ₅ (C ₃ H ₆ O) ₂ H, -O (C ₂ H ₄ O) ₃ O R ',

Another class of polyethers (Fb) may be polyethersiloxanes of the formula (VIII):

[(R ⁷ O) ₃ SiO] ₂ SiR (OC ₂ H ₄ ) R) _c (OC ₃ H ₆ ) _d OT (Villa)

(R ⁷ O) ₃ Si (OC ₂ H ₃ R) _c (OC ₃ H ₆ ) _d OT (VIII b)

wherein R is as defined above. Each R ⁷ is independently a monovalent hydrocarbon radical, with the proviso that the majority (> 50 mol%) of R ^{7 are} sterically hindered sec- or tert-C ₃ -C 18 -alkyl or cycloalkyl groups with c> 4, d> O, and with the further proviso that, by the appropriate choice of c and d, they are small enough to set the aforementioned ^' 3-minute value ^' for the contact angle on the surface of the crosslinked elastomer.

T is hydrogen or a monovalent alkyl or alkenyl radical or a group of the formula -Si (R) [OSi (OR ⁷ ) ₃ ] ₂ . Preferably, T is -CH 3, R ⁷ is sec-butyl, c is> 5 and d is = O. Exemplary ethoxylated surfactants of formula (VIII) are described in US Pat. Nos. 4,160,776; US 4,226,794 and US 4,337,168. The products were, for example, under the name "SILFAC" Fa. ONn Corp. available as polyethoxylated silicates such as SILFAC 12M.

Some or all of the compositions of the invention may be present in admixture with the other individual components of the composition and stored as conventional curable silicone compositions. In 2 or more component compositions, the surfactant may expediently be present in all or one of the components in order, if appropriate, to react with a reactive component of the multicomponent silicone compositions, as in the case of remaining SiH 2. Groups in a silicone polyether polymer to exclude. In addition, mold release agents such as fatty acid or fatty alcohol derivatives, colorants and / or color pigments or stabilizers may be used as adjuvant (F). The stability to hot air exposure can be increased, for example, with known hot air stabilizers, such as Fe, Ti, Ce compounds in the form of their oxides, inorganic and organic salts and complexes but a number of organic antioxidants.

If the modified oxidic filler according to the invention is used in curable compositions, one or more non-curing partial mixtures can be provided in a manner known per se, which are mixed with one another before the application or curing to form the curing composition, and wherein at least one the said, non-curing sub-mixtures containing the modified oxidic filler according to the invention. In a preferred embodiment, an addition-crosslinking silicone rubber mixture is prepared by preparing at least two partial mixtures (1) and (2) which comprises more than one but not all of the components (A) to (F) and the filler according to the invention. The preferred division into partial mixtures serves to improve handling and storage, in which the reaction of the hardening components with one another is achieved by dividing the reactive and catalyzing components containing constituents (A) to (F) and the filler according to the invention until immediately before mixing - can postpone all components before mixing. For the preparation of non-reacting partial mixtures, for example, a partial mixture (1), consisting of the components (A), filler and (C) and optionally (D) and (F), as well as a partial mixture (2), consisting at least of Component (B) and optionally filler, (E) and (F) prepared by mixing. In principle, all possible sub-mixtures can be used for a longer storage, as long as the components (A), (B) and (C) are not present simultaneously in a partial mixture. Therefore, it is convenient to separate component (B) and (C) when simultaneously (A) is present or when one separates (B) and (A) when (C) is present in the same part mixture at the same time. The component (C) can be kept more or less advantageously in each of the components, as long as the mutually reacting grain components (A), (B) are present side by side. The inhibitor (E) can be present in each partial mixture, the combination in a partial mixture with (B) being preferred.

The compositions described above which contain the surface-modified oxidic fillers obtained by the process according to the invention are used, for example, for the production of molded articles, impression compounds or coatings. The fillers produced according to the invention serve to reinforce the (rubber) mechanical properties. Preferred examples of said shaped articles are, for example, impression compounds, such as dental impression compounds, replica forms, gaskets, such as so-called "formed-in-place" gaskets, so-called "conformal coatings", any shaped articles, such as (embossing ) Stamping and (embossing) pressure pads for the "padprinting" process, printing inks (low viscosity compositions for marking or labeling flexible substrates, such as indexable mats) The filler modified according to the invention is used to prepare hydrophilic silicone rubber compositions containing it by way of example have the following components:

(A) 100 parts by weight of at least one alkenyl-containing polyorganosiloxane having a viscosity range of 0.025 and 500 Pa.s, (25 ⁰ C;

Shear rate gradient D of 1 s ^-1 ),

(B) from 0.1 to 200 parts by weight of at least one polymethylhydrogen siloxane, with the proviso that 1 to 10 mol of SiH units are used per mole of unsaturated groups in (A) and (F) (C) 1 to 50 parts by weight, more preferably 5 to 40 parts by weight of the modified oxidic filler according to the invention, preferably precipitated or pyrogenic silica

(D) 0.5 to 1000 ppm, preferably 10-50 ppm, of at least one hydrosilylation catalyst, preferably platinum in the form of salts or siloxane complexes, calculated as metal, based on the amount of components (A) to (B) + (F), (E) optionally from 0.0001 to 2% by weight of one or more inhibitors, based on the amount of components (A) to (F),

(F) 0.1-20 parts by weight of a polyethersiloxane of the type H ₂ C =CH-P- (CH ₃ ) ₂ SiO - [(CH ₃ ) ₂ SiO] o _-2 - [CH ₃ ZSiO] i _-5 -Si (CH ₃ ) ₂ -P-CH = CH P = single bond or -Ci-i- _O- alkylene with Z = - (CH ₂ ) SO (C ₂ H ₄ O) I _-2 OR 'and

R '= C 1 -C ₉ -alkyl.

The abovementioned molded articles, impression materials or coatings produced according to the invention are expediently obtained by curing the compositions containing the fillers according to the invention. Preferably, the compositions are poured into molds or offered as a curable casting material.

Examples

Example 1 (comparison)

In an evacuable paste mixer 10.2 kg of a vinyl-terminated polydimethylsiloxane having a viscosity of 10 Pa.s at 25 ⁰ C, 16.1 kg of a vinyl-terminated polydimethylsiloxane having a viscosity of 1 Pa.s at 25 ⁰ C. , 0.92 kg of water and 2.8 kg of hexamethyldisilazane (as reactive silane i)). 8.0 kg of fumed silica having a BET surface area of 300 m ² / g and 7.8 kg of fumed silica having a BET surface area of 130 m ² / g were mixed in. During the mixing, the temperature increased. The mixture was kept at 65 ^° C. for 1 hour. Thereafter, the volatile components were distilled off in vacuo at up to 140 ⁰ C. The mixture was then gradually diluted with 8.0 kg of the vinyl-terminated polydimethylsiloxane having a viscosity of 1 Pas to a mixture A.

To determine the rheological behavior, 150 g of mixture A were mixed with 165 g of the vinyl-terminated polydimethylsiloxane having a viscosity of 1 Pas mixed and obtained in this way a mixture B with a concentration of 15 wt.% Of silica. The weight fraction of trimethylsiloxy groups taken up by the filler surface in the above process was not taken into account in the calculation. In 98.6 g of the mixture B, 1.6 g of a trimethylolpropane-started polyether having a molecular weight of about 6000 and an EO: PO ratio of 30: 70 was mixed. This resulted in a no longer flowing mixture. This polyether-containing blend and blend B without polyether additive were measured in a rotary mode using a Bohlin cone / plate geometry rheometer. The measurement began at a shear rate of 0.1 [s ^"1] nand 25 ⁰ C. The shear rate was reduced to 10 ^[s" increased ^1], and then backwards again reduced to 0.1 [s ^"1] The return curve. evaluated.

This example demonstrates the strong thickening effect of the polyether in a blend of polydimethylsiloxane and hydrophobic silica made according to the prior art, as described for example in US 4,101,499, US 4,162,243 or in US 5,777,002 Technique was hydrophobicized.

Example 2 (comparison)

2500 g of the mixture A were mixed with 44 g of water and the mixture was stirred at about 3O ⁰ C for 6 hours. After the mixture had stood overnight, 134 g of hexamethyldisilazane were mixed and stirred at 55 ⁰ C for 1 hour. Thereafter, it was heated from up to 140 ⁰ C and the volatiles removed in vacuo. This resulted in mixture B. This was like in the Example 1 diluted again to a silica content of 15 wt.% And tested without and with the addition of polyether Theological.

This example shows that the repetition of the ^' in situ ^' loading with hexamethyldisilazane in the presence of water leads to a reduction in the thickening effect after addition of the polyether, but does not yet bring about a satisfactory result.

Example 3 (according to the invention)

In 2500 g of the mixture A, 134 g of hexamethyldisilazane were mixed. After standing overnight, the mixture was warmed to about 50-55 ^° C. and kept in this temperature range for 1 hour. It was then heated to 140 ⁰ C and the volatiles removed in vacuo. C. C. It was diluted again to 15% by weight and tested as described in Example 1.

This example shows that the oxidic filler treated by the process according to the invention leads to a mixture which only thickened very little by the addition of polyether. Example 4 (comparison)

569 g of a vinyl-terminated polydimethylsiloxane having a viscosity of 10 Pa.s, 1344 g of a vinyl-terminated polydimethylsiloxane having a viscosity of 1 Pa.s, 35 g of water and 156 g of hexamethyldisilazane were mixed together. Then, 446 g of fumed silica having a BET surface area of 300 m ² / g and 435 g of fumed silica having a BET surface area of 130 m ² / g were gradually mixed. After 30 minutes stirring at about 35 ⁰ C 156 g silazane Hexamethyldi¬ were added. After the mixture had stood overnight, was heated to 140 ⁰ C and the volatiles were removed in vacuo. The resulting mixture D was diluted again to 15% by weight of silica and tested as described in Example 1.

This comparative example shows the behavior obtained by adding further hexamethyldisilazane after mixing in the silica without first removing the volatiles. Such a method, as described in US 4,785,047 or WO 98/58997 or WO 00/61074, brings no improvement.

Example 5 (according to the invention)

569 g of a vinyl-terminated polydimethylsiloxane having a viscosity of 10 Pa.s, 1344 g of a vinyl-terminated polydimethylsiloxane having a viscosity of 1 Pa.s, 51 g of water and 156 g of hexamethyldisilazane were mixed together. Then, stepwise 446 g of fumed silica having a BET surface area of 300 m ² / g and 435 g of fumed silica having a BET surface area of 130 m ² / g mixed. Thereafter, 30 minutes at 30 - 35 ⁰ C stirred. It was then heated to 142 ⁰ C and the volatiles removed in vacuo. After the mixture was cooled to 60 ⁰ C, 156 g of hexamethyldisilazane were added again but no water. The mixture was stirred for about 1 hour at about this temperature and reheated to 140 ^° C. In vacuo, volatiles were removed. The mixture E obtained in this way was tested after dilution to a silica content of 15% by weight, as described in Example 1.

In this example of the invention, the reaction times were deliberately chosen very short. The result is not quite as good as in Example 3 but far surpasses that of all comparative examples.

Claims

claims

A method of producing an oxide filler comprising the steps of:

a. Mixing at least one reactive silane i) with at least one oxidic filler, if appropriate in the presence of water, b. Separating low-boiling constituents contained in the mixture, c. Add at least one reactive silane ii), without adding water and optionally heating the mixture.

2. The method of claim 1, wherein step a) is carried out in a liquid, continuous phase.

A process according to claim 2, wherein the liquid, continuous phase is formed by a polymer or a curable composition whose reinforcement is to serve the oxidic filler.

4. The method according to any one of claims 1 to 3, wherein the reactive silanes i) of step a) are selected from the group consisting of: organosilazanes, hexaorganodisilazanes, organosilanols, trialkylsilyl amines, Trialkylsilyloximen, trialkylsilylamides or organoalkoxysilanes.

5. The method according to any one of claims 1 to 4, wherein the reactive silanes ii) of step c) are selected from the group consisting of organosilazanes, hexaorganodisilazanes, trialkylsilylamines, Trialkylsilyl¬ oximes or trialkylsilylamides.

6. The method according to any one of claims 1 to 5, wherein the oxide filler is selected from silicic acids.

7. Filler, obtainable according to one of claims 1 to 6.

8. Compositions containing at least one filler according to claim 7 and at least one polymer or a crosslinkable composition.

9. The composition according to claim 8, characterized in that it comprises at least one polyorganosiloxane.

10. The composition according to claim 8 or 9, characterized in that the crosslinkable composition contains the following components:

(A) at least one polyorganosiloxane having at least two unsaturated groups per molecule,

(B) at least one polyhydrogen organosiloxane having at least 2 SiH groups per molecule,

(C) At least one oxidic filler according to claim 8,

(D) at least one hydrosilylation-promoting catalyst selected from the group of compounds or metals containing at least one element selected from Pt, Ru, Rh, Ni, Ir, Ru and Pd,

(E) optionally one or more inhibitors which delay the hydrosilylation reaction,

(F) optionally one or more auxiliaries.

11. A composition according to any one of claims 8 to 10, characterized gekenn¬ characterized in that it contains at least one surfactant as an excipient (F).

12. The composition according to any one of claims 8 to 11, characterized gekenn¬ characterized in that it contains at least one polyether compound as an auxiliary (F).

13. The composition according to claim 12, characterized in that the polyether compound has reactive groups which participate in the Vernetzungs¬ reaction of the crosslinkable composition.

14. The composition according to claim 13, characterized in that the reactive groups are selected from hydroxyl groups, Si-alkenyl groups, alkenyloxy groups and Si-H groups.

15. A composition according to any one of claims 8 to 14, characterized in that it contains:

(A) 100 parts by weight of at least one alkenyl group-containing polyorganosiloxane siloxane having a viscosity range of 0.025 to 500 Pa.s, (25 ⁰ C; shear velocity gradient D of 1 s ^"1),

(B) from 0.1 to 200 parts by weight of at least one polymethylhydrogen siloxane, with the proviso that 1 to 10 moles of SiH units are present per mole of unsaturated groups in (A) and (F),

(C) 1 to 50 parts by weight of the oxide filler according to claim 8,

(D) 0.5 to 1000 ppm of at least one hydrosilylation catalyst calculated as metal based on the amount of components (A) to (B) + (F),

(E) optionally from 0.0001 to 2% by weight of one or more inhibitors, based on the amount of components (A) to (F),

(F) is 0.1 - 20 parts by weight of a Polyethersiloxanes type H2C = CH-P- (CH3) 2SiO - [(CH3) 2SiO] o-2 - [(CH3) ZSiO] i-5-Si (CH ₃₎ 2 -P-CH = CH2 with P = a single bond or Ci-io-alkylene and

Z = - (CH ₂ ) SO (C ₂ H ₄ O) I _-20 R 'with R' = H, C 1 -C 9 -alkyl.

16. Use of the filler according to claim 7 in polyether-containing polysiloxane compositions.

17. Use of the compositions according to any one of claims 8 to 15 for the production of molded articles, impression materials or coatings.

18. Use of the compositions according to one of claims 8 to 15 for the production of dental impression materials, punches, pressure pad for the

Padprinting process and printing inks.

19. A process for the production of molded articles, impression materials or Beschich¬ lines, which comprises the curing of the compositions according to any one of claims 8 to 15.

20. Cured compositions obtainable by curing the compositions according to any one of claims 8 to 15.