DE102005035443A1 - Preparation of binding materials, useful for sealing electrical/electronic parts, comprises flame pyrolytic separation of silicon dioxide layer on a substrate; applying hardenable silicon composition over addition reaction; and hardening - Google Patents

Abstract

Preparation of binding materials (I) comprises flame pyrolytic separation of a silicon dioxide layer on a substrate; applying hardenable silicon composition (a) over an addition reaction; and hardening the group by precipitation at below 80[deg]C. An independent claim is also included for binding materials (I) obtained by the method.

Description

object The invention is a process for producing composite materials and the composite materials obtained by this method characterized in that on a substrate prior to application a silicone composition by means of a silicon dioxide layer flame pyrolytic deposition is applied.

As is known the liability of addition-curing silicone elastomers on numerous Substrates such as plastics, metals and glasses become low, i.e., become addition-crosslinking silicone elastomer composition applied to a substrate and subsequently crosslinked, the resulting silicone elastomer can usually easily, i.e. by applying low tensile forces, subtracted from the substrate surface become; becomes common even a spontaneous replacement of the silicone elastomer from the substrate. Because in numerous However, applications have a firm and lasting adhesion to the substrate Silicone elastomers is of vital importance has been a variety special measures proposed to establish a firm bond between substrate and silicone elastomer to achieve.

Basically the adhesive strength of the silicone elastomer-substrate composite is increased, by the chemical and / or physical nature of the addition-curing Siliconelastomermasse is deliberately changed and this silicone composition is cured in contact with the material at temperatures above 100 ° C. Known are numerous adhesion-promoting additives, which - the uncrosslinked Silicone compound added - one Self-adhesion of the resulting silicone elastomer on various Create substrates. Which includes Compounds containing highly reactive functional groups, such as Alkoxy, epoxy, carboxy or amino groups, these being Groups mostly so selected Be that internal bonding agent with both the substrate as well as react with a silicone elastomer ingredient. Although it is possible by such adhesion promoter in individual cases a pretreatment of the substrate are omitted, but corresponds the achieved adhesion often not the requirements. Also, an increase in Adhesive strength due to higher Contents of these adhesion promoters only conditionally possible, since the contained in it highly reactive groups then increasingly disadvantageous to the performance properties impact. Here are in particular the storage stability, for example by demixing the components of such compositions which Crosslinking characteristic (inhibition) and the toxicological Therefore, it is of great interest the content of adhesion promoters as low as possible to hold, or even completely to get along without such addictive. For missions in the Areas of medical technology or food is usually the Addition of this highly reactive and toxicologically questionable internal Adhesives prohibited.

Bedeutendster Disadvantage of all procedures to composite materials using the described, self-adhesive reacting by internal adhesion promoters Making silicone compositions is the mandatory requirement curing the composite in the heat. All bonding agent systems described so far require for Building a fixed network an additional energy input sufficiently activate the reactive groups of the adhesion promoters. This results in numerous disadvantages such as the evaporation of volatile and partly toxic components, tensions by very different thermal expansion coefficients or even the limitation Systems that have the high curing temperatures survive over 100 ° C without damage.

Next The technical need is not least the need for economic improved method of such composite materials cost-optimized without additional To produce heat input.

In the European patent application EP 0 686 671 A2 will describe a self-adhesive addition-crosslinking composition that does not require a special adhesion promoter, since the adhesion-promoting component is either an organohydrogenpolysiloxane having on average per molecule at least two SiH groups and its monovalent Si-bonded radicals to at least 12 mol .-% of hydrocarbon radicals with a aromatic ring, or is such a compound having on average per molecule at least one SiH group and containing a group consisting of two aromatic rings, wherein the two aromatic rings by - (RR'Si) -, - (RR'SiO ), -O- (RR'SiO) - or - (RR'Si) -O- (RR'Si) units are separated from each other and the radicals R and R 'represent monovalent, optionally substituted hydrocarbon radicals. The adhesion-promoting constituent may therefore at the same time be the crosslinker of the silicone elastomer composition. With this composition, good adhesion to organic plastics such as acrylonitrile-butadiene-styrene copolymers (ABS) is achieved while at the same time a slight mold release from the metal vulcanization mold, such as a chrome or nickel-coated steel mold or an aluminum alloy mold, is pointed out. However, the high content of aromatic ring-containing residues in the SiH-containing, adhesion-promoting component of at least 12 mol% requires considerable incompatibility with the other constituents of the addition-crosslinking silicone elastomer composition. On the one hand, this leads to partial segregation (sweating out) during storage, which necessitates repeated homogenization of the component containing this constituent before use. This incompatibility, which is already evident in a milky turbidity of the uncrosslinked mass, is also manifested in a significantly reduced transparency of the silicone elastomer parts produced therefrom. If the adhesion-promoting component simultaneously acts as crosslinker of the silicone elastomer composition, the incompatibility leads to vulcanization disorders which lead to inhomogeneous network formation and inadequate mechanical vulcanizate properties. In order to circumvent these vulcanization disorders, in addition to the adhesion-promoting SiH-containing constituent, a SiH-containing crosslinker which is completely compatible with the silicone elastomer mass must be used, but this has other disadvantages, such as increased values of the compression set or an increased exudation tendency of the adhesion-promoting constituent. The high content of aromatic ring-containing residues in the SiH-containing adhesion promoting ingredient of at least 12 mole percent also causes significant intrinsic viscosity and thixotropy of the silicone elastomer composition which is undesirable in many applications, such as electronic component casting. Finally, the adhesion of this composition to metals is insufficient.

The European disclosure EP 0 875 536 A2 discloses a pressure-sensitive addition-crosslinking silicone rubber mixture, characterized in that the self-adhesive addition-crosslinking silicone rubber mixture consists essentially of at least one linear or branched organopolysiloxane having at least two alkenyl groups, at least one hydrogen siloxane having at least 20 SiH groups per molecule, which outside the Si-H groups exclusively monovalent aliphatic radicals having 1 to 8 carbon atoms, with the proviso that the ratio of Si-H to Si-alkenyl groups is at least 1.5, at least one Pt or Rh catalyst, at least one epoxy-functional alkoxysilane and / or alkoxysiloxane and optionally, further Excipients and a peroxide exists.

Particularly preferred is the use of glycidyloxypropyltrimethoxysilane (Glymo). In the EP 0 875 536 A2 described silicone rubber mixture is particularly suitable for the production of composite moldings, which consist of the silicone elastomer and an organic plastic. In the EP 0 875 536 A2 However, the composition described has the disadvantage that only when using very SiH-rich crosslinkers, with an average of at least 20 SiH groups per molecule, a sufficient adhesive strength can be achieved. Crosslinkers containing 30 SiH groups per molecule are used in the examples there. The use of such highly functional crosslinkers considerably reduces the storage stability of addition-crosslinking silicone rubber mixtures. For example, the flowability is massively impaired. This can lead to Verestammung of the mass, whereby a procedural processing of the mass, for example by injection molding, is no longer possible. In addition, in order to achieve a high adhesive strength, relatively high amounts of epoxy-functional alkoxysilane / siloxane must be used, whereby the crosslinking rate, especially at relatively low curing temperatures is significantly reduced.

In order to become the addition-curing silicone elastomer compositions according to the state of Technology does not sufficiently meet the requirements Self-adhesive silicone elastomer composition, which in particular for the production from connected or for sealing or potting electrical / electronic Parts should be used, be-made.

• i. eine hohe Vernetzungsgeschwindigkeit bei relativ niedrigen Temperaturen, bevorzugt bei Raumtemperatur,
• ii. eine hohe Haftfestigkeit auf organischen Kunststoffen, Metallen und Gläsern unmittelbar nach Aushärtung der Siliconmasse,
• iii. die toxikologische Unbedenklichkeit sowie
• iv. sehr gute Gebrauchseigenschaften, wie beispielsweise Transparenz, Nichtkorrosivität und mechanisches Eigenschaftsprofil.

Essential properties according to the aforementioned requirements are, for example:

• i. a high crosslinking rate at relatively low temperatures, preferably at room temperature,
• ii. a high adhesive strength on organic plastics, metals and glasses immediately after curing of the silicone composition,
• iii. the toxicological safety as well
• iv. very good performance properties, such as transparency, non-corrosivity and mechanical property profile.

It was therefore an object to provide a process for the production of composite materials of organic plastics, metals or glasses with addition-crosslinking silicone elastomer compositions, the does not have the disadvantages of the prior art and thus meets the above requirement profile.

The The object underlying the present invention was surprising by applying a silicidioxidhaltigen coating on the substrate by flame pyrolytic decomposition of silicon-containing, dissolved vaporizable substances become.

• (a) Aufbringen einer silizidioxidhaltigen Beschichtung auf das Substrat durch flammenpyrolytische Zersetzung von siliciumhaltigen, verdampfbaren Substanzen,
• (b) Applizierung der additionsvernetzenden Siliconzusammensetzung auf die Beschichtung des Substrates und
• (c) Aushärtung des Verbundes bei Temperaturen unter 80°C.

The subject of the present invention is therefore a process for the production of composite materials, comprising the process steps

• (a) applying a silicide-containing coating to the substrate by flame-pyrolytic decomposition of silicon-containing vaporizable substances,
• (b) applying the addition-crosslinking silicone composition to the coating of the substrate and
• (C) Curing of the composite at temperatures below 80 ° C.

The advantageous properties of the method are that to the desired Achieving high bond strengths no additional energy input through curing is needed at high temperatures. Rather, over the curing at room temperature, the voltage problems by greatly different thermal expansion coefficients avoided, as well as undesirable Evaporation of volatile siloxane components or crosslinking-related fission products and the associated Prevented contamination problems. By the pyrolytic deposition the silica-containing coating becomes a contamination-free surface achieved with consistently high surface activity, in combination with the silicone compositions of the invention ensures high bond strengths. On intensive cleaning steps of the substrate surface can also be dispensed with. Another advantage is that through the Use of the method according to the invention enabled Abandonment of the aforementioned internal adhesion promoters in the silicone composition and the utter one Exclusion of with the addition of the above-described problems.

The fast curing and the rapid achievement of high bond strengths when cured at room temperature allows short cycle times and timely follow-up process steps due to the absence of cooling or tempering loops. For opens up the user over now the inventive method the new possibility Composite materials with high bond strength using manufacture addition-curing silicone compositions without heat curing.

The flame pyrolytic deposition of the silicon dioxide layer on the substrate surfaces, referred to in process according to the invention as process step (a), can be carried out, for example, with a commercially available flame-treatment apparatus. In this case, in a preferred embodiment of the flame, a silane gas is supplied, which burns in the flame to silicon dioxide and is deposited on the substrate surface. This process is known in the art, for example, the term "PYROSIL ^® process".

• (A) mindestens ein Diorganopolysiloxan der allgemeinen Formel (1) R1 aR2 bSiO(4-a-b)/2 (1)worin R¹ einen Hydroxylrest oder einen monovalenten, gegebenenfalls halogensubstituierten Kohlenwasserstoffrest mit 1 bis 20 Kohlenstoffatomen, der gegebenenfalls O-, N-, S-, oder P-Atome enthalten kann und der frei von aliphatisch ungesättigten Gruppen ist, R² einen monovalenten, aliphatisch ungesättigten, gegebenenfalls halogensubstituierten Kohlenwasserstoffrest mit 2 bis 10 Kohlenstoffatomen, der gegebenenfalls O-, N-, S-, oder P-Atome enthalten kann, und b Werte von 0,003 bis 2 bedeuten, mit der Maßgabe, dass 1,5 < (a+b) < 3,0, pro Molekül durchschnittlich mindestens zwei aliphatisch ungesättigte Reste R² enthalten sind und die bei 25°C bestimmte Viskosität der Diorganopolysiloxane (A) 1 mPa·s bis 40.000 Pa·s beträgt,
• (B) mindestens ein Organohydrogenpolysiloxan mit durchschnittlich zumindest 2 siliciumgebunden Wasserstoffatomen pro Molekülkette und
• (C) zumindest einen Hydrosilylierungskatalysator.

The addition-crosslinking silicone compositions which are applied in a preferred embodiment in process step (b) of the process according to the invention contain

• (A) at least one diorganopolysiloxane of the general formula (1) R 1 a R 2 b SiO (4-ab) / 2 (1) wherein R ^{1 is} a hydroxyl radical or a monovalent, optionally halogen-substituted hydrocarbon radical having 1 to 20 carbon atoms, which may optionally contain O, N, S or P atoms and which is free of aliphatically unsaturated groups, R ^{2 is} a monovalent, aliphatic unsaturated, optionally halogen-substituted hydrocarbon radical having 2 to 10 carbon atoms, which may optionally contain O, N, S or P atoms, and b is from 0.003 to 2, with the proviso that 1.5 <(a + b) <3.0, an average of at least two aliphatically unsaturated radicals R ² per molecule and the viscosity of the diorganopolysiloxanes (A) determined at 25 ° C. is 1 mPa.s to 40,000 Pa.s,
• (B) at least one organohydrogenpolysiloxane having on average at least 2 silicon-bonded hydrogen atoms per molecule chain and
• (C) at least one hydrosilylation catalyst.

In a particularly preferred embodiment are obtained bonds with particularly high adhesion, if the addition-curing silicone compositions used in step (b) of the method have a ratio of [SiH] / [SiVi]> 1.1, wherein [SiH] for the concentration of silicon-bonded hydrogen atoms and [SiVi] for the concentration the aliphatically unsaturated Groups throughout the silicone composition.

The Components (A), (B) and (C) can contain a compound or a mixture of different compounds.

Examples of radicals R ¹ according to the invention are alkyl radicals, such as methyl, ethyl, propyl, isopropyl, tert-butyl, n-pentyl, iso-pentyl, neo-pentyl, tert-pentyl, n Octyl, 2-ethylhexyl, 2,2,4-trimethylpentyl, n-nonyl and octadecyl; Cycloalkyl radicals, such as cyclopentyl, cyclohexyl, cycloheptyl, norbornyl, adamantylethyl or bornyl radical; Aryl or alkaryl radicals, such as phenyl, ethylphenyl, tolyl, xylyl, mesityl or naphthyl radical; Aralkyl radicals, such as benzyl, 2-phenylpropyl or phenylethyl radical, and halogenated and organically functionalized derivatives of the above radicals, such as 3,3,3-trifluoropropyl, 3-iodopropyl, 3-isocyanatopropyl, aminopropyl, methacryloxymethyl or cyanoethyl radical. Preferred radicals R ¹ contain 1 to 10 carbon atoms and optionally halogen substituents. Particularly preferred radicals R ¹ are methyl, phenyl and 3,3,3-trifluoropropyl, in particular the methyl radical.

The radicals R ² are accessible to a hydrosilylation reaction. Examples of these are alkenyl and alkynyl radicals, such as vinyl, allyl, isopropenyl, 3-butenyl, 2,4-pentadienyl, butadienyl-5-hexenyl, undecenyl, ethynyl, propynyl and hexynyl radical; Cycloalkenyl radicals, such as cyclopentenyl, cyclohexenyl, 3-cyclohexenylethyl, 5-bicycloheptenyl, norbornenyl, 4-cyclooctenyl or cyclooctadienyl radical; Alkenylaryl radicals, such as styryl or styrylethyl radical, and halogenated and heteroatom-containing derivatives of the above radicals, such as 2-bromovinyl, 3-bromo-1-propynyl, 1-chloro-2-methylallyl, 2- (chloromethyl) allyl, Styryloxy, allyloxypropyl, 1-methoxyvinyl, cyclopentenyloxy, 3-cyclohexenyloxy, acryloyl, acryloyloxy, methacryloyl or methacryloyloxy. Preferred radicals R ² are vinyl, allyl and 5-hexenyl, in particular the vinyl radical.

at the diorganopolysiloxanes (A) of the general formula (1) is at 25 ° C viscosity between preferably 100 mPa · s up to 30,000 Pa · s. Particularly preferred is the viscosity range of 1 to 30,000 Pas. Depending on the type of addition-crosslinking compound, different Viscosity ranges especially prefers. For which become known as RTV-2 (room temperature vulcanizing) masses viscosities from 100 to 10,000 mPa · s particularly preferred, for LSR (liquid silicone rubber) from 1 to 100 Pa · s, for HTV (high temperature vulcanizing) from 2,000 to 40,000 Pa · s.

The Organohydrogenpolysiloxane (B) preferably contains per molecule an average of 5 to 50 SiH groups. The measured at 25 ° C viscosity of ingredient (B) preferably 2 mPa · s to 5 Pa · s.

by virtue of the lability the SiH group, the component (B) manufacturing a low content, typically below 100 ppm by weight, Si-bonded Have OH groups.

Hydrosilylation catalyst (C) serves as a catalyst for the addition reaction, referred to as hydrosilylation, between the aliphatically unsaturated hydrocarbon radicals R ^{2 of} the diorganopolysiloxanes (A) and the silicon-bonded hydrogen atoms of the organohydrogenpolysiloxanes (B). Numerous suitable hydrosilylation catalysts are described in the literature. In principle, all the prior art and used in addition-crosslinking silicone rubber compositions hydrosilylation catalysts can be used.

When Hydrosilylation catalyst (C) may include metals such as Platinum, rhodium, palladium, ruthenium and iridium, preferably Platinum, as well as their compounds are used. The metals can optionally on finely divided support materials, such as Activated carbon, metal oxides, such as alumina or Silica, be fixed.

Preferably, platinum and platinum compounds are used. Particularly preferred are those platinum compounds which are soluble in polyorganosiloxanes. As soluble platinum compounds, for example, the platinum-olefin complexes of the formulas (PtCl ₂ · olefin) ₂ and H (PtCl ₃ · olefin) can be used, preferably alkenes having 2 to 8 carbon atoms, such as ethylene, propylene, isomers of butene and Octens, or cycloalkanes having 5 to 7 carbon atoms, such as cyclopentene, cyclohexene and cyclohepten used. Other soluble platinum catalysts are the platinum-cyclopropane complex of Formula (PtCl ₂ C ₃ H ₆ ) ₂ , the reaction products of hexachloroplatinic acid with alcohols, ethers and aldehydes or mixtures thereof or the reaction product of hexachloroplatinic acid with methylvinylcyclotetrasiloxane in the presence of sodium bicarbonate in ethanolic solution. Also, platinum catalysts with phosphorus, sulfur and amine ligands can be used, such as (Ph ₃ P) ₂ PtCl ₂ . Particular preference is given to complexes of platinum with vinylsiloxanes, such as, for example, sym-divinyltetramethyldisiloxane.

The amount of hydrosilylation catalyst (C) used depends on the desired crosslinking rate and on economic aspects. Usually, per 100 parts by weight of diorganopolysiloxanes (A), preferably 1 × 10 ^-5 to 5 × 10 ^-2 parts by weight, in particular 1 × 10 ^-3 to 1 × 10 ^-2 parts by weight of platinum catalysts calculated used as platinum metal.

The addition-curing silicone compositions may optionally further Ingredients (D), such as fillers, inhibitors, stabilizers, Pigments, co-catalysts or peroxides.

In order to achieve a sufficiently high mechanical strength of the crosslinked silicone rubber, it is preferable to incorporate active reinforcing fillers as component (E) in the addition-crosslinking silicone compositions. As active reinforcing fillers (E) are mainly used precipitated and fumed silicas, and mixtures thereof. The specific surface area of these active reinforcing fillers should be at least 50 m ² / g or preferably in the range from 100 to 400 m ² / g as determined by the BET method. Such active reinforcing fillers are well known materials in the silicone rubber art.

The curing of the composite, the erfindugsgemäßen process as a process step (c) is carried out at temperatures below 80 ° C. Prefers will harden at temperatures of 20 to 50 ° C, particularly preferably carried out at room temperature.

In the following examples are, unless stated otherwise, all pressures 0.10 MPa (abs.) And all temperatures 20 ° C.

substrates

• a) Polybutylenterephthalat (PBT): Ultradur^® B4300G6 (BASF AG, Ludwigshaven/Deutschland; 30% GF)
• b) Polyamid 6: Durethan^® BKV30 (Bayer AG, Leverkusen/Deutschland; 30% GF)
• c) Polycarbonat (PC): Lexan^® (GE Plastics, Fairfield/U.S.A)
• d) Aluminium (Industriequalität; nicht grundiert)

The bond strength of the composites produced according to the invention and not according to the invention was tested on the following substrates:

• a) polybutylene terephthalate (PBT): Ultradur ^® B4300G6 (BASF AG, Ludwigshafen Haven / Germany; 30% GF)
• b) polyamide 6 Durethan ^® BKV30 (Bayer AG, Leverkusen / Germany; 30% GF)
• c) polycarbonate (PC): Lexan ^® (GE Plastics, Fairfield / USA)
• d) aluminum (industrial grade, not primed)

Flame Pyrolytic Pretreatment the substrate surface

The flame-pyrolytic deposition of the silicon dioxide layer on the substrate surfaces is carried out with the flame-treatment device FB25, which is marketed by the company SURA INSTRUMENTS, Jena / Germany. The flame is in this case the Silangasgemisch supplied PYROSIL ^® , which is burned in the flame to silica and deposited on the substrate surface. The surface is treated twice with the "pale blue area" of the flame The speed at which the flame is swept across the surface is 5 mm / s, yielding an effective 5 mm width of deposition strip.

Characterization of the liability

The bond strengths are carried out in accordance with DIN EN 1465 "Tensile shear strength of high-strength overlap bonds for metallic joining parts." To characterize the release stresses, 100.0 g of a crosslinker-free addition-crosslinking liquid silicone elastomer base material containing 70.0% by weight of diorganopolysiloxane with a viscosity of 20,000 mPa.s, 30 , 0 wt .-% reinforcing filler and 10 ug platinum catalyst, intimately mixed with a predetermined amount of crosslinking agent.This mass is immediately after mixing as a layer of about 1.0 mm thick pretreated in accordance with the previously described method Surface of the substrate applied with a squeegee. Subsequently, a second identically pretreated substrate body is brought into contact with the silicone composition. The contact area is approximately 200 mm ² for all test specimens. The silicone composition then cures completely at room temperature within 30 minutes. By means of a tensile stretching machine immediately after curing, the maximum force is measured, which is necessary to dissolve the adhesive bond. The maximum value of this force, based on the contact area of 200 mm ² , is given as the break-away stress in N / mm ² . For each example, 5 laminates are measured, the tear-off stress is determined as the mean value and the percentage of cohesive failure is determined. Cohesive failure of 0% means that the silicone elastomer has been completely and residue-free removed from the substrate surface. Cohesive failure of 100% means that delamination from the two substrate bodies was solely due to crack growth within the silicone elastomer.

Example 1 (according to the invention):

To 100 g of the base described above are 1.10 g of a polydimethyl-co-methylhydrogensiloxanvernetzers mixed with 0.32 wt .-% hydrogen. The resulting crosslinkable silicone composition is as described above applied to the substrates and composite bodies receive.

Example 2 (non-inventive comparative example):

As Example 1, but without flame pyrolytic pretreatment.

Example 3 (noninventive comparative example):

As Example 1, but only 0.85 g of polydimethyl-co-methylhydrogensiloxane crosslinker with 0.32 wt% added to 100 g of the basic mass.

Example 4 (comparative example not according to the invention):

As Example 2, however, will be additional to 100 g of crosslinkable Silicone composition 1.0 g of glycidyloxypropyltrimethoxysilane as internal Reactive coupling agent added.

Example 5 (according to the invention):

As Example 1, but 0.80 g of a polydimethyl-co-methylhydrogensiloxane crosslinker mixed with 0.45 wt% hydrogen

Example 6 (according to the invention):

As Example 1, but 0.40 g of a polydimethyl-co-methylhydrogensiloxane crosslinker admixed with 1.1 wt% hydrogen

Example 7 (non-inventive comparative example):

As Example 5, but 0.50 g of a polydimethyl-co-methylhydrogensiloxane crosslinker mixed with 0.45 wt% hydrogen

Example 8 (comparative example not according to the invention):

As Example 6, but 0.25 g of a polydimethyl-co-methylhydrogensiloxane crosslinker admixed with 1.1 wt% hydrogen

• * nicht erfindungsgemäß

The results of the adhesion measurements are given in Table 1. Table 1: (Breakdown stress in [N / mm ² ], proportion of cohesive failure in [%])

• * not according to the invention

The The values given in Table 1 demonstrate the high adhesive strength of the according to the inventive method produced composites (Examples 1, 5 and 6) and various organic Plastics or metals. As can be seen from Example 2 is, without the flame pyrolytic pretreatment is not high Adhesive strength of the composite achieved. Examples 3, 7 and 8 show that only high bond strengths are achieved if the Process is carried out with silicone compositions whose ratio of molar contents of Si-H to Si-vinyl compounds not smaller 1.1 is. In turn, Examples 1, 5 and 6 of the invention show that then achieved synergistic effects with high bond strengths when the process is carried out with silicone compounds, their relationship the molar contents of Si-H to Si-vinyl compounds greater than 1.1 is. Example 4 shows that also by the addition of known to be extremely effective internal adhesion promoters, such as glycidyloxypropyltrimethoxysilane, alone, no high bond strength can be achieved. such need internal adhesion promoter Activation temperatures of over 100 ° C to self-adhesion To achieve effects.

Claims (10)

Process for the production of composite materials having the following steps (a) flame pyrolytic deposition a silicon dioxide layer on a substrate, (b) Order one over an addition reaction curable Silicone composition and (C) curing of the composite at temperatures below 80 ° C. A method according to claim 1, characterized in that as an addition reaction-curable silicone composition in process step (b) an addition-crosslinking silicone composition is used, the (A) at least one diorganopolysiloxane of the general formula (1) R 1 a R 2 b SiO (4-ab) / 2 (1) wherein R ^{1 is} a hydroxyl radical or a monovalent, optionally halogen-substituted hydrocarbon radical having 1 to 20 carbon atoms, which may optionally contain O, N, S or P atoms and which is free of aliphatically unsaturated groups, R ^{2 is} a monovalent, aliphatic unsaturated, optionally halogen-substituted hydrocarbon radical having 2 to 10 carbon atoms, which may optionally contain O, N, S or P atoms, and b is from 0.003 to 2, with the proviso that 1.5 <(a + b) <3.0, per molecule on average at least two aliphatically unsaturated radicals R ^{2 are} contained and determined at 25 ° C viscosity of the diorganopolysiloxanes (A) 1 mPa.s to 40,000 Pa.s, (B) contains at least one organohydrogenpolysiloxane having on average at least 2 silicon-bonded hydrogen atoms per molecule chain and (C) at least one hydrosilylation catalyst. Method according to claim 1 or 2, characterized that over an addition reaction curable Silicone composition a ratio [SiH] / [SiVi]> 1.1 wherein [SiH] is the concentration of the silicon-bonded hydrogen atoms and [SiVi] the concentration of the aliphatically unsaturated Groups throughout the silicone composition. Method according to one of claims 1 to 3, characterized that at 25 ° C certain viscosity of the diorganosiloxane (A) is between 100 mPa.s to 30,000 Pa.s. Method according to one of claims 1 to 4, characterized that the organohydrogensiloxane (B) has an average of 5 to 50 Si-H groups per molecule contains. Method according to one of claims 1 to 5, characterized that over an addition reaction curable Silicone composition furthermore constituents (D) selected from the group containing fillers, Inhibitors, stabilizers, pigments, co-catalysts or peroxides contains. Method according to one of claims 1 to 6, characterized that over an addition reaction curable Silicone Composition Further Reinforcing Fillers as Component (E) contains. Method according to claim 7, characterized in that that over an addition reaction curable silicone composition as component (E) contains fumed silica. Method according to one of claims 1 to 8, characterized that (c) curing of the composite is carried out at temperatures of 20 to 50 ° C. Composite materials obtainable by a process according to one the claims 1 to 9.