DE102004013742A1 - Shaping process using a silicone rubber composition - Google Patents

Abstract

The invention relates to a process for the preparation of a silicone membrane for a "Resin Transfer Molding" process, in which a sprayable, solvent-free silicone composition is used, which cures in thick layers to form a thick-walled, transparent, flexible separating membrane. This is used in a molding process for producing plastic parts from fiber-reinforced curable casting resins.

Description

The The invention relates to a process for the preparation of resin moldings by a transfer method using a silicone rubber composition, in a spray process applied and at room temperature to flexible separation membranes with good mechanical strength can be cured as well as the Use of the silicone rubber composition for manufacturing a separation membrane. The separation membrane according to the invention is in a Shaping process for the production of plastic parts from (fiber-reinforced in particular glass fiber reinforced) curable casting resins used.

The Production of especially large molded parts in small batches makes special demands on an economic molding technique.

These Procedures are used in the small series production of sporting goods, Karroserien, special machinery, decoration parts, coverings, Boats, planes, etc. used.

The fundamental Principle is an inexpensive rigid mother mold, on one side covered or closed with a flexible membrane, wherein in the space between the mother mold and membrane a curable Cast resin filled and, where appropriate, reinforcing Elements or reinforcing fibers or Tissue can be inserted.

The Cast resin for such Method selects one expediently the curable at low temperatures casting resins out and fill these by pouring, Pressing or sucking with the help of pressure or a vacuum in the vorformed shape gap.

If with large individual Shapes for Small series are to be worked, stand no preformed elastomeric membranes as flexible separation membranes available. The demands more adequate Strength and the desire to be able to use the membranes repeatedly mechanically thick enough through thick-walled membranes Silicone rubber meet.

therefore so far came, if not previously prepared, preformed Separating membranes for the Manufacturing could be used, membranes used one with painting, casting or Filling techniques made on site. As a minimum strength is necessary, come here only thick-walled membranes from mechanical sufficiently strong silicone rubber for use. These thick-walled Membranes should as possible be made in a short time. This one has already been next to many other film-like and layered materials, such as thermoplastics and elastomers also different silicone rubbers under use used different application techniques. The conflict of goals between short networking time and long open time for undisturbed processing while of the order, e.g. troweling, as well as the requirement vertical surfaces not expire, led on the one hand a) for the selection of systems that are unsatisfactorily long Have drying times and on the other hand b) too fast crosslinking systems. These are e.g. a) Silicone rubbers, which are either very pseudoplastic until thixotropic, for that but a long time to cure need or on the other hand b) faster curing systems, but with which only thin Layers in coherent Layer could be applied because of these systems because of the short Have been selected in low viscous form, to be applied quickly. Another embodiment consisted in the addition of solvents, about the viscosity for one to lower fast order.

It is known in the art that silicone rubbers only when applied from reinforcing fillers lead to high strength flexible silicone membranes after crosslinking.

Of the Addition of such fillers but in the corresponding optimal concentration usually leads to pseudoplastic Masses on a relatively high viscosity level, thus can be do not apply such silicone rubbers quickly.

The Therefore, production of such membranes has always been laborious because either long curing times had to be accepted or only thin layers per operation could be applied, in turn, a repeated coating required.

Accordingly should be sought a silicone rubber and a process that It allows, in a short time, a thick-walled membrane in a few To be able to produce work steps at room temperature.

The patent US 2,913,036 and the GB 944,955 describe a method of making glass fiber reinforced plastic moldings in which a one-sidedly rigid mold is filled with reinforcing fibers and sealed by a flexible, transparent and impermeable cover. The mold space between mold and cover is filled with a curable resin by means of an applied vacuum. The bubble-free filling is controlled through the transparent cover.

The reactive casting resin is cured in the mold, then the transparent cover and the molded part are separated from the rigid mold. The flexible cover can be used several times depending on the material and manufacturing process. The process is often referred to in later patents as "Resin Transfer Molding" ( US 4,762,740 ).

For the impermeable, flexible cover was used in addition to various materials such as rubber, nylon and polyethylene US 3,666,600 For the first time, silicone rubber has also been disclosed as the preferred flexible cover material and used for good release properties and reusability.

Silicone elastomer as the material for the impermeable membrane is also used by the U.S. 5,576,030 and US 5,807,593 , in general form.

Likewise, the teaches US 5,958,325 in that large parts can be produced by transfer molding using a 'silicone bag'. The US Pat. No. 6,623,323 describes, for example, the production of surfboards with the help of silicones.

Examples of suitable silicone materials for producing a flexible separation membrane are disclosed in the patents US 5 087 193 . US 5,433,165 , WO95 / 32849, US 5 526 767 . US 5 641 525 and US 5,702,663 disclosed. The products described for this purpose must be applied in several layers and cured between the applications. The application takes place depending on the consistency by doctoring or brushing. In some cases, diluted silicone compounds are applied with organic solvents. The process is complex and time consuming. Dilutions with solvents are undesirable. The use of organic solvents, however, are contrary to both environmental protection requirements (VOC guidelines EU Directive of 11.3.99) as well as occupational safety and health laws.

The US 5,433,165 extends the process for making a boat hull by means of a flexible 'vacuum bag' of transparent 'reinforced' silicone rubber by vulcanizing into the silicone layer a mesh for reinforcement. To prepare the separating bag, in turn, the silicone rubber is diluted with solvent and applied in layers and then cured. Other patents like US 4,698,115 or U.S. 4,878,979 teach you how to seal flexible covers made of prefabricated silicone rubber parts, eg with silicone glue.

In the prior art according to US 5 087 193 There is also evidence of how to reinforce a silicone membrane with glass fiber fabric, using wax as an intermediate layer to form the membrane on the rigid molding. From the information on the silicone product GE RTV 700 with beta 2 hardener and 910 thinner, it can be seen that a condensation-crosslinking silicone rubber which contains Sn or Ti compounds of the like as the catalyst was used here.

The same silicone rubber is used in the US 5 526 767 proposed and used with dilution with solvents, wherein this is applied in numerous layers on the prefabricated hull and cured.

The WO95 / 32849 describes the manufacture of hulls by means of a vacuum bag with the silicone rubber Dow Corning Tooling Elastomer THT. This "viscous" silicone mixture is applied in several layers to an intermediate layer of wax.

This Silicone material is transparent, has a viscosity of 45 Pas, is easy to spread, stable and hardens after adding the catalyst but only in 24 hours.

In the US 5,665,301 are used comparable moisture-curing, transparent 1 K silicone rubbers, which are applied in several layers to a thickness of 3 to 4 mm together and cure as a thin layer within one hour. A similar procedure will be used in US 5,702,663 taught. These systems release after exposure to moisture cleavage products from the crosslinkers used, which is undesirable.

The US 5 641 525 describes unspecified 2K silicone products for the production of the silicone sack. The US 4,822,436 describes how to make flexible silicone bags by spray and coat application with addition vulcanizable silicone rubbers by diluting such a rubber with solvents, but without mentioning other parameters. However, attention is drawn to the problem of limited life due to observed shrinkage. Reference is also made to the relevant transfer molding technical literature: Dow Corning's New Product Information Bulletin entitled "Use of High Strength RTV Silicone Rubber in Contour Vacuum Bag Molding." In the EP 874032 describes a sprayable addition crosslinkable silicone rubber which is to be used as an antifouling coating in a marine environment. It consists of vinyl-containing polyorganosiloxanes, platinum catalyst and polyorganohydrogensiloxanes, of which it is concluded that this silicone rubber composition must be diluted to be applied by spraying or brushing with a solvent. However, the composition must adhere to the hull and the application is naturally made in small thicknesses. The document thus provides no indication of the use of sprayable, solvent-free silicone compositions for the production of thick-walled separation membranes.

Other low-viscosity silicone rubbers which can be crosslinked by means of the hydrosilylation reaction, ie are addition-crosslinkable, and have good mechanical strength in the cured state, are, for example, in US Pat US Pat. No. 3,697,473 and US 4,340,709 disclosed, but there was not solved the problem of spraying order in the sense of the task set here.

It has so far been unable to produce a transparent, solvent-free, sprayable silicone system can not be found on vertical moldings before curing expires Cures at room temperature in a short time and in the cured state has good mechanical properties. The creation of such material would the Production in particular large Moldings made of glass fiber reinforced Enormously facilitate and accelerate resins as well as working conditions because of missing solvent vapors or Improve cleavage products of crosslinkers.

in the present state of the art there is no indication how to make a flexible cover or separation membrane made of silicone rubber can, where you can avoid the use of solvents and nevertheless to a fast order and short curing time with good removability at the same time from the carrier or model and sufficient mechanical strength.

The The object of the present invention was to provide a silicone composition to provide in a process for the preparation of a silicone membrane for a "Resin Transfer molding process can be used. The process should be suitable, a sufficiently tear-resistant or thick-walled, transparent separating membrane with simple means in a short time to produce locally, using in a "Resin Transfer molding process herewith large plastic parts manufacture.

The inventive solution The task was accomplished by combining a two-component spray application process with a fast-curing silicone rubber, which during the short curing time only slightly from vertical surfaces and runs off has a high strength after crosslinking.

The Inventors of the present patent application are surprised succeeded, all these partially conflicting requirements by the Use of a special order material to meet.

The used silicone composition must under the conditions of Spray application have a sufficiently low viscosity, on the one hand so low that the composition can be applied by spraying on the other hand hardens sufficiently quickly, so they do not spray from oblique or vertical moldings expires. Furthermore, she has to join Cure ambient temperature rapidly to a transparent silicone rubber. To must the Transparency have a level that allows, by about 5 mm thick layer through bubbles in the casting resin to recognize.

The mechanical strength of the cured in a short time silicone composition must be exempt In order to survive the removal of the silicone cover from the mold or the replica, the cured resin, without damage. This ensures a multiple usability of the separation membrane.

• a) Bereitstellung einer Mutterform,
• b) Herstellung einer Trennmembran, durch Besprühen eines Trägermaterials mit einer härtenden Silikonzusammensetzung,
• c) Zusammensetzen der Mutterform und der in Schritt a) erhaltenen Trennmembran unter Schaffung eines Hohlraums zwischen der Mutterform und der Trennmembran,
• d) gegebenenfalls Einführen von verstärkenden Materialien in den genannten Hohlraum,
• e) gegebenenfalls Anlegen eines Vakuums an den Hohlraum,
• f) Auffüllen des Hohlraums mit einer härtbaren Harzzusammensetzung,
• g) Aushärten der Harzzusammensetzung,
• h) Entfernen der Trennmembran und
• i) Entformen des Harzformkörpers aus der Mutterform,

dadurch gekennzeichnet, dass die genannte sprühbare, härtende Silikonzusammensetzung enthält:

• (A) mindestens ein alkenylgruppenhaltiges Polyorganosiloxans mit einem Viskositätsbereich von 0,025 und 40 Pa·s (25°C; Schergeschwindigkeitsgefälle D von 1 s^-1),
• (B) mindestens ein Polyorganohydrogensiloxan,
• (C) gegebenenfalls einen oder mehrere Füllstoffe,
• (D) mindestens einen Hydrosilylierungskatalysator,
• (E) gegebenenfalls einen oder mehrere Inhibitoren.

The inventors of the present invention have surprisingly found that, in order to achieve the above-described object, a method for producing resin moldings by a transfer method is suitable, which comprises the following steps:

• a) providing a parent form,
• b) preparing a release membrane by spraying a support material with a curing silicone composition,
• c) assembling the mother mold and the separating membrane obtained in step a) to create a cavity between the mother mold and the separating membrane,
• d) optionally introducing reinforcing materials into said cavity,
• e) optionally applying a vacuum to the cavity,
• f) filling the cavity with a curable resin composition,
• g) curing the resin composition,
• h) removing the separation membrane and
• i) removal of the resin molding from the mother mold,

characterized in that said sprayable, curable silicone composition comprises:

• (A) at least one alkenyl group-containing polyorganosiloxane having a viscosity range of 0.025 and 40 Pa · s (25 ° C., shear rate gradient D of 1 s ^-1 ),
• (B) at least one polyorganohydrogensiloxane,
• (C) optionally one or more fillers,
• (D) at least one hydrosilylation catalyst,
• (E) optionally one or more inhibitors.

The general technical implementation of steps a) to i) is known per se, but in the method according to the invention Special features from the preferred two-component spray application using substantially solvent-free silicone compositions result. Since these compositions have very short pot lives, the spray application takes place preferably by combining at least two subcomponents, which are so designed that they do not simultaneously contain the components (A), (B) and (D) included. For this purpose, conventional two-component spray guns, as for example Polyurethane systems such as those of Graco or Hilger and Kern and static mixer with preferably a length to diameter ratio of about> 10 as you for example used by the companies Sulzer or Kenics. But it can also combinations of static mixers, especially dynamic Static mixers and simple spray guns are used.

(a) Provide a Mother die

The Mother form usually includes Molds of metal or plastic, at least in part the surface or determine the shape of the replica.

(b) Preparation of a Separating membrane, by spraying a carrier material with a hardening Silicone composition

The support material may be the mother form itself or a complementary shape be of it. The carrier material can also be made of metal, plaster, modeling clay or plastic, which is possibly reinforced, consist. On the carrier material is optionally used according to the invention using a release layer Silicone composition, as explained above, preferably by two-component spray application sprayed. By using the special fast-curing silicone composition can be repeated by spraying in a short time Time a relatively thick-walled separation membrane are produced, the above has sufficient mechanical strength. Preferred layer thicknesses are from 1 to 30 mm, preferably from 3 to 12 mm. Less fast curing Systems could in this way in the speed of the process according to the invention less well processed, as the materials applied while of the contract.

(c) assembling the Mother mold and the separation membrane obtained in step a) under creation a cavity between the mother mold and the separation membrane and

(d) optionally introducing reinforcing Materials in said cavity.

To curing the separation membrane can this with the mother mold optionally after Coating the parent mold with a release agent and inserting reinforcing Materials such as fiber mats, nonwovens and other fabrics or reinforcing elements, together be, leaving a cavity between the silicone separation membrane and forms the mother form. Between the mother mold and the silicone separation membrane or openings are provided in the silicone separation membrane the evacuated gap can be evacuated or flooded.

(e) If necessary, create a vacuum to the cavity.

Of the resulting cavity can be useful especially well filled with the casting resin if you have either a slight overpressure or a vacuum there applies, preferably a vacuum is applied to a bubble-free, faster filling to allow the cavity.

(f) replenishing the Cavity with a curable Resin composition.

in the Connection is made the padding the cavity with at least one curable resin composition. This may be, for example, radically started, curing unsaturated organic Compounds such as monomer compositions, oligomer or polymer compositions act, the usual if necessary other auxiliaries, fillers, Dyes contain. For example, styrene, acrylic group-containing Compounds or unsaturated Polyester can be used.

Farther can addition-curing resin compositions are used, such as For example, isocyanate-containing, epoxy-containing crosslinkable monomers, Oligomers or polymers, suitable crosslinkers, such as polyols, polyamines etc., included.

(g) curing the Resin composition

To the filling the hardening Resin composition in the cavity, the curing takes place in familiar way. Preferably, the curing at 0 ° C to about 60 ° C optionally takes place with the help of trace heaters on the moldings, more preferably at room temperature 15 ° C up to about 40 ° C.

(h) removing the separation membrane.

To curing the resin composition in the cavity becomes the separation membrane of removed from the mother mold. The separation membrane can then be used for the next molding process become.

(i) Removing the resin molding from the mother form,

Then you can the formed resin moldings be removed from the mother mold and other processing steps be subjected in a conventional manner.

• (A) mindestens ein alkenylgruppenhaltiges Polyorganosiloxans mit einem Viskositätsbereich von 0,025 und 40 Pa·s (25°C; Schergeschwindigkeitsgefälle von 1 s^-1),
• (B) mindestens ein Polyorganohydrogensiloxan,
• (C) gegebenenfalls einen oder mehrere Füllstoffe,
• (D) mindestens einen Hydrosilylierungskatalysator,
• (E) gegebenenfalls einen oder mehrere Inhibitoren
• (F) gegebenenfalls weitere Hilfsstoffe..

The sprayable, curable silicone composition used according to the invention advantageously contains:

• (A) at least one alkenyl group-containing polyorganosiloxane having a viscosity range of 0.025 and 40 Pa · s (25 ° C., shear rate gradient of 1 s ^-1 ),
• (B) at least one polyorganohydrogensiloxane,
• (C) optionally one or more fillers,
• (D) at least one hydrosilylation catalyst,
• (E) optionally one or more inhibitors
• (F) optionally further auxiliaries ..

In the silicone rubber compositions used in the present invention, the alkenyl group-containing polyorganosiloxane (A) has a viscosity range of 0.025 and 40 Pa · s (25 ° C., shear rate D of 1 s ^-1 ). It may consist of a uniform polymer or mixtures of different polyorganosiloxanes (A1) or (A1) and (A2).

The polyorganosiloxane (A) preferably consists at least of the siloxane units which are selected from the group consisting of the units M =R ¹ R ₂ SiO _1/2 , D =R ¹ RSiO _2/2 , T =R ¹ SiO _{3 / 2} , Q = SiO _4/2 and the divalent units R ² , wherein R, R ¹ and R ^{2 are} as defined below. The polyorganosiloxanes (A) are preferably prepared by catalytic equilibration or catalyzed polycondensation. The viscosity and alkenyl concentration resulting from this polyreaction after evaporation of the low molecular weight constituents, respectively, defines the polyorganosiloxane (A), for example prepared as in US 6,387,487 Column 3 u. Discloses 4, which is present in this form each alone or in the form of blends of different types of polymers, blends are preferred.

The polyorganosiloxane (A) can be described by the general formula (I): [M _a D _b T _c Q _d ] _m (I)

Therein, the siloxy units M, D, T and Q can be distributed in blocks or randomly in the polymer chain and linked to one another. Within the polysiloxane chain, each siloxane unit may be the same or different. The indices are preferably as follows and are expediently selected in accordance with the desired viscosity:
m = 1-1000
a = 1-10
b = 0-1000
c = 0-50
d = 0-1.

The aforementioned polyorganosiloxanes (A) or mixtures thereof containing the polyorganosiloxanes (A1) and (A2) preferably have a structure of the general formula (Ia) for the polyorganosiloxanes (A1) which are substantially linear and have a content of unsaturated have organic groups, which is preferably between 0.035 to 1.0 mmol / g. The content of unsaturated organic groups refers to polymethylvinylsiloxanes and must be adapted within the given viscosity limits to siloxy groups with a higher molecular weight. R ¹ R ₂ SiO (R ¹ RSiO) _b1 SiR ₂ R ¹ (Ia), preferably of formula (Ia ') R ¹ R ₂ SiO (R ₂ SiO) _b1 SiR ₂ R ¹ (Ia ') wherein
R, R ¹ and R ^{2 are} as defined below and
b1 <1000.

In the above radicals, R is an organic group, which is preferably selected from unsubstituted and substituted hydrocarbon radicals, such as n-, iso-, tert- or C ₁ -C ₁₂ alkyl, C ₁ -C ₁₂ alkoxyalkyl, C ₅ -C ₃₀ cycloalkyl or C ₆ -C ₃₀ aryl, C ₁ -C ₁₂ alkyl (C ₆ -C ₁₀ ) aryl, which may optionally be substituted by one or more O or F atoms and are, for example, ethers.

Examples of suitable monovalent hydrocarbon radicals R include alkyl groups, preferably CH ₃ , CH ₃ CH ₂ , (CH ₃ ) ₂ CH, C ₈ H ₁₇ and C ₁₀ -C ₂₁ groups, cycloaliphatic groups, such as cyclohexylethyl, aryl groups, such as phenyl, tolyl, xylyl, aralkyl groups such as benzyl and 2-phenylethyl groups. Preferred monovalent halohydrocarbon radicals R have the formula C _n F _{2n + 1} CH ₂ CH ₂ - wherein n has a value of 1 to 10, such as, for example, CF ₃ CH ₂ CH ₂ -, C ₄ F ₉ CH ₂ CH ₂ - and C ₆ F ₁₃ CH ₂ CH ₂ -, the more preferred radical is the 3,3,3-trifluoropropyl group.

Especially preferred R is methyl, phenyl, 1,1,1-trifluoropropyl.

In the above groups, R ^{1 is} an alkenyl-containing organic group, which is preferably selected from unsubstituted and substituted alkenyl-containing hydrocarbon radicals, such as C ₂ -C ₁₂ n-, iso-, tert- or cyclic alkenyl, vinyl, allyl, hexenyl, C ₆ -C ₃₀ -cycloalkenyl, cycloalkenylalkyl, norbornenylethyl, limonenyl, C ₈ -C ₃₀ -alkenylaryl, which are each substituted by one or more O or F atoms, for example ethers.

Preferred radicals R ¹ are groups such as vinyl, allyl, 5-hexenyl, cyclohexenylethyl, limonenyl, norbornenylethyl, ethylidene norbornyl and styryl, particularly preferably vinyl.

R ² 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} selected from divalent aliphatic or aromatic n-, iso-, tert- or cyclic C ₁ -C ₁₄ -alkylene, C ₆ -C ₁₄ -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 ) ₁₈ -cycloalkylene groups such as cyclohexylene, arylene groups such as phenylene, xylene. Their proportion does not exceed 30 mol .-% of all siloxy units. Preference is given to groups such as alpha, omega-ethylene, alpha, omega-hexylene or alpha, omega-phenylene.

The term substantially linear includes polyorganosiloxanes (A) which preferably contain not more than 0.1 mole% of siloxane units selected from the T = RSiO _3/2 or Q = SiO _4/2 units.

In the polyorganosiloxanes (A1), the radical R is preferably methyl with at least 90 mol% (i.e., 90 to 99 mol% of Si atoms), preferably at least 95 mol% before.

The Polyorganosiloxanes (A1) contain at least 2 unsaturated organic Residues. Preferably, they contain 0.035 to 1.0 mmol / g more preferably 0.05 to 0.8 mmol / g alkenyl groups. The content of unsaturated Organic groups refers to polymethylvinylsiloxanes and is within the given viscosity limits on siloxy groups with higher Adjust molecular weight.

The Alkenyl groups can either at the chain end of a silioxane molecule or as a group at one Silicon atom be bound in the siloxane chain. Preferably lie the alkenyl groups only at the chain end of the siloxane molecule. When alkenyl groups are present on silicon atoms of the siloxane chains, its content is preferably less than 0.01 mmol / g.

Around the mechanical properties, such as the tear propagation resistance to improve the cross-linked products will be useful blends various polymers (i.e., at least 2 polymers (A1) or at least (A1) and (A2) before) with different alkenyl content and / or different chain length used, the entire Content of unsaturated Groups 1.0 mmol / g in the component (A) does not exceed functional.

preferred Siloxy units are, for example, alkenyl units, such as dimethylvinylsiloxy, Alkyl units, such as trimethylsiloxy, dimethylsiloxy and methylsiloxy units, aryl units such as phenylsiloxy units, such as triphenylsiloxy-dimethylphenylsiloxy, Diphenylsiloxy, phenylmethylvinylsiloxy, phenylmethylsiloxy units.

The polyorganosiloxane (A) preferably has a number of siloxy units of from 20 to 1000, particularly preferably from 100 to 800 (average degree of polymerization P _n , which relates to polymethylvinylsiloxanes and is to be adapted to higher molecular weight siloxy groups within the prescribed viscosity limits).

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.

Preferably the alkenyl group content is given by alkenyldimethylsiloxy units shown as end-of-chain siloxy units. In these cases one strict difunctionality the alkenyl content is also over the viscosity definable. This is preferred in these for the polymer (A1) embodiment the alkenyl content clearly with the chain length or the degree of polymerization and therefore the viscosity connected.

The polyorganosiloxane (A1) and the mixture of (A1) and (A2) have a viscosity of 0.025 to 40 Pa · s, most preferably 0.2 to 20 Pa · s at 25 ° C. The viscosity is measured according to DIN 53019 at 25 ° C and a shear rate gradient D = 1 s ^-1 .

The alkenyl groups R ¹ are preferably bonded to terminal silicon units. The olefinic group is located at the C ₃ -C ₁₂ alkenyl groups on the terminal carbon atom, since these alkenyl groups are more reactive. The claimed here C ₃ -C ₁₂ alkenylsiloxanes are for example derived from precursors using alpha, omega-haloalkenes or alpha, omega-dienes.

A further class of preferred polymers (A) which together with (A1) form component (A) are branched polyorganosiloxanes (A2) which can be used to increase, for example, tear strength or tensile strength in combination with other polyorganosiloxanes, such as those defined above. if no or little reinforcing filler of component (C) is used. These polyorganosiloxanes (A2), such as. In US 3,284,406 . US Pat. No. 3,699,073 disclosed contain an increased content of unsaturated radicals R ¹ , but in contrast to these have an increased proportion of branched or branching siloxane units T = RSiO _3/2 or Q = SiO _4/2 units, which are more than 0, 1 mol%, based on the existing Si atoms, are present. However, the amount of branching units should be limited by the fact that this component should preferably be liquid, low melting (mp <160 ° C) or with the other polymers (A) miscible, transparent silicone compositions (> 70% transmission at 400 nm and 2 mm layer thickness).

The above-mentioned highly branched polyorganosiloxanes are polymers containing the aforementioned M, D, T and Q units. They preferably have the general formula (II), (IIa) to (IIb): [M _a2 D _b2 T _c2 Q _d2 ] _m1 (II) {[R ₁ SiO _3/2 ] [R ³ O _1/2 ] _n1 } _m1 (IIa) {[SiO _4/2 }] [R ³ O _1/2 ] _n1 [R ₂ R ¹ SiO _1/2 ] _0.01-10 [RSiO _3/2 ] _0-50 [R ₂ SiO _2/2 ] _{0 -500} } _m1 (IIb) wherein R ^{3 is} a C ₁ to C ₂₂ organic radical such as alkyl, aryl or arylalkyl.

The radical R ³ O _1/2 is preferably methoxy, ethoxy or hydroxy with the preferred indices n1
m1 = 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, the Units M, D and T may contain the radicals R or R ¹ .

The Alkenylgruppenreichen branched polyorganosiloxanes (A2) include in particular liquid Polyorganosiloxanes, solid resins or liquid resins soluble in organic solvents preferred are trialkylsiloxy (M units) and silicate units (Q units), and the preferred vinyldimethylsiloxy units in an amount of at least 0.2 mmol / g. These resins can about that In addition, up to a maximum of 10 mol% of alkoxy or OH groups on the Si atoms have.

In the aforementioned branched polyorganosiloxanes (A2) is the Radical R is preferred as the methyl radical of at least 50 mol% (i.e., 50th mol%) to 95 mol% of Si atoms), preferably at least 80 mol%, before. The alkenyl-rich, preferred vinyl group-rich, polyorganosiloxane (A2) preferably has one Alkenylgruppengehalt of more than 0.35 mmol / g to 11 mmol / g, which refers to polymethylvinylsiloxanes and within the given viscosity limits on siloxy groups with higher Is to adjust molecular weight.

The Polyorganosiloxanes (A) can in principle in any ratio of (A1) to (A2) with each other be mixed. Preferably, the ratio (A1): (A2) is more 2.5: 1. The mixture of polyorganosiloxanes (A1) and (A2) has a viscosity of less than 40 Pa · s at 25 ° C

In a preferred embodiment of the invention comprises the polyorganosiloxane (A) substantially linear polyorganosiloxanes (A1) as described above. branched Polyorganosiloxanes (A2) as described above may be added to improve the mechanical properties, especially when the amount of filler (C) for example, for reasons the viscosity is limited.

Another preferred blend of the polyorganosiloxanes (A) contains two substantially linear alkenylene end-stopped polyorganosiloxanes (A1) having different alkenyl, preferably vinyl, contents. By this measure, on the one hand, the lowest possible viscosity of the silicone composition should prevail On the other hand, a crosslinking structure with the below-defined Si-H compounds of component (B) are made possible, which effects the highest possible mechanical strengths, such as elongation and tear resistance of the crosslinked silicone rubbers. If larger amounts of short-chain alpha-omega-vinylsiloxanes (suitably below a viscosity of 10 Pa.s) are used, this requires larger amounts of alpha, omega-Si-H-siloxanes as so-called chain extenders to form suitable crosslinking structures. The viscosity for the polyorganosiloxanes (A) is in the case of R = methyl in the range of 25 to 40,000 mPa · s at 25 ° C at a shear rate gradient D of 1 s ^-1 .

An alkenyl group-containing, non-blended polydiorganosiloxane of type (A) is defined by the fact that the distribution of the weight and number average has resulted from one of the known polymerization reactions, preferably from the equilibration or polycondensation with basic or acidic catalysts. Such processes with alkaline or acidic catalysts are, for example, in US 5 536 803 Column 4 discloses. 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, both the different Cyclosiloxanes, linear polyorganosiloxanes, as well as symmetric 1,3-divinyltetramethyldisiloxane, other longer chain siloxanes with a Trialkylsiloxy end stop or OH end groups are used. exemplary you put this for it the hydrolysates of different alkylchlorosilanes, such as vinyldimethylchlorosilane and / or dimethyldichlorosilane and the trialkyl terminated therefrom Siloxanes for or mixed with other siloxanes.

The average degree of polymerization P _{n of} the polyorganosiloxane (A), measured as number average M _n by GPC and with polystyrene as standard, is preferably in the range of P _n > 20 to 1000, the more preferred range is Pn 200 to 800.

The Polymers (A) defined herein, in combination with suitable, Polyhydrogenorganosiloxanen the component described below (B) the production of separation membranes that are sufficiently good rubber mechanical Properties such as elongation at break, tensile strength and tear propagation resistance as well as stability have the mechanical properties and by spraying, in particular two-component spray application, can be processed.

The polyorganohydrogensiloxanes (B) are preferably linear, cyclic or branched polyorganosiloxanes whose siloxy units are suitably selected from M = R ₃ SiO _1/2 , M ^H = R ₂ HSiO _1/2 , D = R ₂ SiO _2/2 , D ^H = RHSiO _2/2 , T = RSiO _3/3 , T ^H = HSiO _3/2 , Q = SiO _4/2 , in which these units preferably consist of MeHSiO or Me ₂ HSiO _0.5 units in addition to optionally other organosiloxy units , preferably dimethylsiloxy units. The polyorganosiloxanes (B) can be described, for example, by the general formula (III) in which the symbols M * for M and M are ^H , D * for D and D ^H and T * for T and T ^{H for the sake of} brevity: [M * _a4 D * _b4 T * _c4 Q _d4 ] _m2 (III) m2 = 1 to 1000
a4 = 1 to 10
b4 = 0 to 1000
c4 = 0 to 50
d4 = 0 to 1.

The Siloxy units can blockwise or randomly linked together in the polymer chain. Each siloxane unit of the polysiloxane chain may be identical or different Wear leftovers.

The Indices of the formula (III) describe the average degree of polymerization Pn measured as number average Mn by GPC, based on polyhydrogenmethylsiloxanes and within the given viscosity limits on siloxy groups with higher Are to adjust molecular weight.

The Polyorganohydrogensiloxane (B) comprises in particular all liquid, flowable and solid polymer structures of the formula (III) with those given above Indices resulting degrees of polymerization. Preferred are the at 25 ° C liquid Low molecular weight polyorganosiloxanes (B), i. less than about 60000 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 SiO (R ₂ SiO) _z (RHSiO) _p SiR ₂ H (IIIa) HMe ₂ SiO (Me ₂ SiO) _z (MeHSiO) _p SiMe ₂ H (IIIb) Me ₃ SiO (Me ₂ SiO) _z (MeHSiO) _p SiMe ₃ (IIIc) Me ₃ SiO (MeHSiO) _p SiMe ₃ (IIId) {[R ₂ YSiO _{1/2] 0-3} [YSiO _3/2] [R ³ O) _{n2} m2} (IIIe) {[SiO _4/2}] [R ³ O _{1/2] n2} [R ₂ YSiO _{1/2] 0.01-10} [YSiO _{3/2] 0-50} [ryšio _{2/2] 0-1000} m2} (IIIf) z = (z1 + z2) = 0 to 1000
p = 0 to 100
z + p = b4 = 1 to 1000
wherein R ³ O _{1/2 is} an alkoxy radical on the silicon,
Y = hydrogen (H) or R, both of which can occur simultaneously in one molecule. R is defined above, preferably R = methyl.

A preferred embodiment of the compound class (IIIe) and (IIIf) are, for example, monomeric to polymeric compounds which can be described by the formula [(Me ₂ HSiO) ₄ Q] _m2 . 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 having a higher molecular weight.

In a particularly preferred selection of the formula (IIIb) with R = methyl and z> 0 indicate the polymeric crosslinkers, a SiH concentration is a preferred value from 0.2 to 12 mmol SiH / g. If z = 0, as in formula (IIIc) with R = methyl, the SiH concentration is preferably 7-17 mmol SiH / g.

In a preferred embodiment According to the invention, the polyorganohydrogensiloxane (B) consists of at least a polyorganohydrogensiloxane (B1) having two Si-H groups per molecule and at least one polyorganohydrogensiloxane of the type (B2) more than two Si-H groups per molecule. In this embodiment the component (B) consists of at least two different ones Organohydrogenpolysiloxanes having different crosslinking structures in conjunction with low viscosity sprayable polysiloxanes Component (A) to give silicone elastomers of high strength. These different Organohydrogenpolysiloxanen can be in essentially assign two functions. Bifunctional polyorganohydrogensiloxanes (B1) act as so-called chain extenders, the polyorganohydrogensiloxanes (B2) higher functionality (> 2) act as crosslinkers. The inventively used Contains silicone composition preferably at least one bifunctional chain extender (81) 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) _z1 (MeHSiO) ₂ SiMe ₃ ,
[(Me ₂ SiO) _z1 (MeHSiO) ₂ ]

The crosslinkers (B2) contain compounds such as:
Me ₃ SiO- (MeHSiO) _p SiMe ₃ ,
HMe ₂ SiO (Me ₂ SiO) _z1 (MePhSiO) _{z 2} (MeHSiO) _p SiMe ₂ H,
(MeHSiO) p,
(HMe ₂ SiO) ₄ Si
MeSi (OSiMe ₂ H) ₃
wherein p, z, z1 and z2 are as defined above.

Such mixtures of so-called chain extenders and crosslinkers can, for example, as in US Pat. No. 3,697,473 described, are used.

• – der Gesamt-Alkenylgehalt der Komponente (A), bevorzugt der Vinylgehalt größer als 0,035 mmol/g,
• – er Kettenverlängerer, bevorzugt ein Polyhydrogenmethlysiloxan, (B1) wird derart bemessen, dass nach Abzug seines molaren SiH-Gehaltes vom Alkenylgehalt der Komponente A) rechnerisch 0,08 bis 0,02 mmol/g Alkenyl der Komponente (A) verbleiben,
• – wobei der Vernetzer (B2) so bemessen wird, dass das molare Verhältnis der Gesamtmenge Si-N (B1) und (B2) zur Gesamtmenge Si-Alkenyl 1,1 bis 1,5 zu 1 ist.

In a further preferred embodiment:

• The total alkenyl content of component (A), preferably the vinyl content greater than 0.035 mmol / g,
• - he chain extender, preferably a Polyhydrogenmethlysiloxan, (B1) is dimensioned such that after deducting its molar SiH content of the alkenyl content of component A) arithmetically 0.08 to 0.02 mmol / g alkenyl of component (A) remain,
• - wherein the crosslinker (B2) is such that the molar ratio of the total amount of Si-N (B1) and (B2) to the total amount of Si-alkenyl is 1.1 to 1.5 to 1.

If an increase in the rate of crosslinking is necessary, this can be achieved, for example, by increasing the ratio of SiH to alkenyl, increasing the amount of catalyst (D) or increasing the proportion of polyorganosiloxanes (B2) containing HMe ₂ SiO _0.5 units become.

The polyorganosiloxanes (B) are preferably liquid or siloxane-soluble at room temperature, ie they preferably have less than 1000 siloxy units, ie they preferably have viscosities below 40 Pa · s at 25 ° C. and D = 1 s ^-1 .

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

The chain length of the chain extenders as component (B1), which consist predominantly of Me ₂ SiO units and HMe ₂ SiO _1/2 , 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 processes known per se, for example with an acidic equilibration or condensation, such as in US 5 536 803 disclosed. The polyorganohydrogensiloxanes (B) can also be reaction products resulting from hydrosilylation of organohydrogensiloxanes with alkenyl-containing siloxanes in the presence of the catalysts (D), the resulting SiH content preferably being within the limits defined above. This results in R ² - or alkylene-bridged organohydrogensiloxanes (B).

The polyorganohydrogensiloxanes (B) may furthermore also be reaction products which have arisen from the condensation of, for example, organohydrogenalkoxysiloxanes (B) with hydroxy- or alkoxysilanes or siloxanes, as described, for example, in US Pat US 4 082 726 eg column 5 and 6 described.

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

The preferred amount of polyorganohydrogensiloxanes (B) is chosen so that the molar ratio the total amount of Si-H to the total amount of Si-alkenyl in the component (A) from 0.5 to 10 to 1, preferably 1.0 to 2.0 to 1, more preferably 1.1 to 1.5 to 1.

About the relationship SiH- to Si-alkenyl units allow many properties, like the rubber-mechanical properties, the crosslinking speed, the stability and the release properties the resin molding influence.

The used according to the invention Silicone rubber compounds also contain either one or several, possibly superficial modified fillers (C).

These include, for example, all finely divided fillers, ie, the particles have less than 100 microns, ie preferably consist of such particles. These may be mineral fillers such as silicates, carbonates, nitrides, oxides, carbon blacks or silicas. The fillers are preferably so-called reinforcing silicas which allow the production of opaque, more transparent elastomers, ie those which improve the rubber-mechanical properties after crosslinking, increase the strength, such as, for example, fumed or precipitated silica with BET surface areas between 50 and 400 m ² / g, which are preferably rendered hydrophobic in a special way here superficially. The component (C), when used, is used in amounts of 1 to 100 parts by weight, preferably 10 to 70 parts by weight, more preferably 10 to 50 parts Parts by weight, based on 100 parts by weight of component (A) used.

Fillers with BET surface areas above 50 m ² / g allow the production of silicone elastomers with improved rubber-mechanical properties. The rubber mechanical strength and the transparency increase in the case of, for example, fumed silicas, such as, for example, Aerosil 200, 300, HDK N20 or T30, Cab-O-Sil MS 7 or HS 5 with increasing BET surface area. Trade names for so-called precipitated silicas, engl. 'Wet Silicas' are Vulkasil VN3 or FK 160 from Degussa or Nipsil LP from Nippon Silica KK

The highest transparency is achieved with fumed silicas having a BET surface area of more than 100, preferably more than 200 m ² / g, more preferably more than 300 m ² / g, which are dispersed in a suitable manner

In addition, if transparency is not required, additional or substitute so-called non-reinforcing extender fillers, such as quartz, diatomaceous earth, cristobalite, mica, aluminum oxides, hydroxides, Ti, Fe, Znoxide, chalks or carbon blacks with BET surfaces from 0.2 to 50 m ² / g. These fillers are available under a variety of trade names such as Sicron, Min-U-Sil, Dicalite Crystallite The so-called Inertfüllstoffe or extenders with BET surfaces below 50 m ² / g should expediently for use in the silicone rubbers according to the invention no particles (<0.005 wt .%) above 100 microns, so that in the further processing no problems in the downstream processing, such as the passage of screens or nozzles occur or the mechanical properties of the molded parts produced therefrom are adversely affected.

The Use of this opacifying fillers is less preferred and suitably takes place only if the Transparency is not important.

With the term filler (C) are the fillers including her to the surface bound hydrophobizing or dispersing agent or Process aids, meaning the interaction of the filler with the polymer, e.g. influence the thickening effect. at the surface treatment the fillers it is preferably a hydrophobing with silanes or siloxanes. It can e.g. 'in situ 'through the Addition of silazanes, such as hexamethyldisilazane and / or divinyltetramethyldisilazane, with the addition of water, 'in situ' hydrophobing is preferred. she can also be used with other common filler-treatment agents such as vinylalkoxysilanes, e.g. Vinyltrimethoxysilane, others Silanes with unsaturated organofunctional groups, such as methacryloxypropyltrialkoxysilanes, but also Polyorganosiloxandiolen with chain lengths of 2-50, the unsaturated organic Wear residues to provide reactive sites for the crosslinking reaction.

Examples for commercial available, silicas hydrophobicized in advance with various silanes are: Aerosil R 972, R 974, R 976 or R 812 or e.g. HDK 2000 or H30 Exemplary trade names for so-called hydrophobized precipitated silicas, engl. 'Wet Silicas', are Sipernat D10 or D15 from Degussa.

These Pre-hydrophobized silicas are less preferred than the 'in situ' - hydrophobed with silazanes Silicas. By selecting the amount of filler type, its quantity and the type of hydrophobing can be the rubber-mechanical Properties and the rheological, i. processing technology Properties of the silicone rubber blends are affected.

In a preferred embodiment contains the invention used Silicone composition at least one reinforcing filler (C).

The choice of BET surface area and filler type can influence the thickening performance of the uncured silicone composition, as well as the transparency and rubber mechanical properties of the cured silicone separation membrane material. BET surface areas of at least 100 m ² / g, more preferably at least 200 m ² / g, are particularly preferred of fumed silicas to produce highly transparent, high strength silicone elastomers. These are particularly preferred for use as a separation membrane because they allow to monitor the bubble-free filling with the curable resin composition. The latter is of great importance for the mechanical strength of the resulting molded part.

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.

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 components (A) to (C).

In the group of the Pt, Rh, Ir, Pd, Ni and Ru compounds, ie their salts, complexes or metals, the component (D) is selected, for example, from the Pt catalysts, in particular Pt ⁰ complexes. Compounds with olefins, more preferably with vinylsiloxanes, such as 1: 1 complexes with 1,3-divinyl-tetramethyldisiloxane and / or tetravinyltetramethyltetracyclosiloxane.

These Pt catalysts are exemplified in US 3,715,334 or US Pat. No. 3,419,593 and Lewis, Colborn, Grade, Bryant, Sumpter and Scott in Organometallics, 1995, 14, 2202-2213.

The preferred Pt ⁰ -olefin complexes are prepared in the presence of 1,3-divinyltetramethyldisiloxane (M ^Vi 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, uncomplexed vinyl siloxanes. These vinyl siloxanes can also act to inhibit addition crosslinking. For this reason, it is expedient to use a platinum preparation which contains the lowest possible excess of inhibiting vinylsiloxane for the rapidly curing addition system according to the invention. It has been found that the catalyst should contain at least 5% by weight of platinum as metal in M ^Vi ₂ , preferably more than 10% by weight and more preferably at least 18% by weight of platinum, measured as metal. It can be diluted with vinyl-terminated polydimethylsiloxanes prior to use for better dosing. The concentration of platinum in the overall system must preferably be at least 1 ppm, more preferably 15 to 40 ppm Pt calculated as metal.

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

The Hydrosilylation rate is determined by the selected catalyst compound, their amount and the nature and amount of the additional inhibitor component (E) determined.

The Quantities of the catalyst are reduced by the costs incurred above limited as well as the reliable catalytic effect downwards. Therefore, quantities are above 100 ppm metal mostly uneconomical, quantities below 1 ppm unreliable.

When carrier for the Catalysts can all solid substances selected as long as they do not undesirably inhibit hydrosilylation. The carriers can selected are from the group of powdered silicas or gels or organic resins or polymers and in accordance with the desired transparency are used, non-opacifying carrier are preferred.

The Speed of the hydrosilylation reaction can be known by a Influence series of connections. This takes influence on the Crosslinking speed, i. one determines, at which temperature and in which time the silicone composition or rubber mixture after the spray application to an elastomeric molded body cures or vulcanized.

For the exact determination of the crosslinking times, a crosslinking in a Vulkameter according to DIN 53529 is carried out. In this case, a time can be determined by measuring the so-called t-values, such as t ₁₀ and t ₉₀ , according to which at a given temperature a 10% - or 90% increase in torque based on the final value of the torque to complete Networking has taken place. By means of a torque change, the cross-linking is measured against an initial state. The resulting torque also correlates with the modulus of elasticity or degree of crosslinking of the elastomer tested. The reaction rate can be reduced at concentrations above 30 ppm of platinum, if appropriate by addition of inhibitors such as vinylsiloxanes, 1,3-divinyltetramethyldisiloxane or tetravinyltetramethyltetracyclosiloxane. Other known inhibitors may also be used, for example ethynylcyclohexanol, 3-methylbutynol or dimethyl maleate.

The inhibitors serve to delay the crosslinking reaction at room temperature for a certain time. Thus, at temperatures from 0 to 30 ° C both a time-limited inhibition (pot life) and a sufficiently rapid and complete crosslinkability (to the extent of free of charge) at elevated temperature.

In principle, everyone can for the Class of the group of platinum metals known inhibitors used be, if not already by selecting the ligands of the catalyst (D) a sufficiently long processing time is achieved. A preferred embodiment is to use the catalyst without the inhibitor (E).

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 Pat US 3,445,420 are described. These are, for example, ethynylcyclohexanol and 3-methylbutynol and the unsaturated carboxylic acid esters of US 4,256,870 and diallyl maleate and dimethyl maleate and the fumarates of US 4,562,096 and US 4,774,111 such as diethyl fumarate, diallyl fumarate or bis (methoxyisopropyl) maleate.

Of the series of unsaturated carboxylic acid esters, preferred inhibitors are the maleates and fumarates of the general formula R ⁵ (OW) _v O ₂ CCH = CHCO ₂ (WO) _v R ⁵ wherein:
R ⁵ is selected from the group of C ₁ -C ₁₀ 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 allyl,
W is independently selected from divalent C2-C4 alkylene radicals, the index 'v' has the value 0 or 1.

The Amount of inhibitor component (E) is chosen so that the desired crosslinking time among the chosen ones Working conditions, in particular in coordination with the catalyst (D) and the other components suitably, i. 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 amount of components (A) to (C).

If the inhibitor component (E) is used are preferably about 0.001 to 0.5 wt.%, Particularly preferably 0.05 to 0.2 wt.% Alkynols at metal contents of component (D) of 10 to 100 ppm added.

Prefers the component (E) is selected from the group consisting of alkynols and vinylsiloxanes.

The used according to the invention addition-crosslinking silicone rubber mixtures continue to be included optionally one or more adjuvants (F), e.g. softener or separating oils, such as polydimethylsiloxane oils, without reactive alkenyl or SiH groups with a viscosity of preferably 0.001 - 10 Pa · s 25 ° C. Furthermore can additional Mold release agents such as fatty acid or fatty alcohol derivatives or extrusion aids, such as PTFE pastes Find use. Here are the compounds that are beneficial demix quickly and migrate to the surfaces. As transparent Colorants or color pigments are useful non-opacifying inorganic Pigments used. The stability after hot air exposure can be 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 increase. The amount of the auxiliary agents (F) is preferably 0 to 15 parts by weight based on 100 parts by weight of component (A) and (B).

• (A) 100 Gewichtsteile mindestens eines alkenylgruppenhaltigen Polyorganosiloxans mit einem Viskositätsbereich von 0,025 und 40 Pa·s (25°C; Schergeschwindigkeitsgefälle D von 1 s^-1),
• (B) von 0,1 bis 200 Gewichtsteile mindestens eines Polyorganohydrogensiloxans,
• (C) gegebenenfalls von 1 bis 100 Gewichtsteile eines oder mehrerer Füllstoffe,
• (D) von 0,5 bis 1000 ppm mindestens eines Hydrosilylierungskatalysators berechnet als Metall bezogen auf die Menge der Komponenten (A) bis (C),
• (E) gegebenenfalls von 0,0001 bis 2 Gew. % eines oder mehrerer Inhibitoren bezogen auf die die Menge der Komponenten (A) bis (C),
• (F) gegebenenfalls weitere Hilfsstoffe.

In a preferred embodiment, the silicone composition used according to the invention comprises:

• (A) 100 parts by weight of at least one alkenyl group-containing polyorganosiloxane having a viscosity range of 0.025 and 40 Pa · s (25 ° C., shear rate gradient D of 1 s ^-1 ),
• (B) from 0.1 to 200 parts by weight of at least one polyorganohydrogensiloxane,
• (C) optionally from 1 to 100 parts by weight of one or more fillers,
• (D) from 0.5 to 1000 ppm of at least one hydrosilylation catalyst calculated as metal based on the amount of components (A) to (C),
• (E) optionally from 0.0001 to 2% by weight of one or more inhibitors, based on the amount of components (A) to (C),
• (F) optionally further auxiliaries.

The Application of the invention used Silicone rubber compositions are obtainable by mixing the components (A) to (F), wherein suitably the substances in preferred Consequences combined, and preferably at least two sub-mixtures immediately before spraying united and reacted.

The Mixing the individual components of the silicone rubber mixture takes place preferably in suitable static mixers, in particular dynamic static mixers, two-component mixing nozzles, such as when spraying usual with reactive paints, but also by connecting all kinds of static mixers and simple spray nozzles. Preferred static mixers are the dynamic static mixers, which support the mixing process by means of rotating mixing elements.

to Preparation of the two partial mixtures are preferably mixed the Polyorganosiloxanes (A), reinforcing fillers (C) and optionally the hydrophobizing agent belonging to (C), preferably hexamethyldisilazane and optionally divinyltetramethyldisilazane preferred with water or the silanols previously prepared therefrom at temperatures of 10 to 100 ° C at least 20 minutes to 120 minutes in a mold suitable for high viscosity materials Mixing unit, such as a kneader, dissolver, planetary mixer or other screw mixers. Then it is evaporated at 120 up to 160 ° C the excess water repellents and water at atmospheric pressure, then optionally in vacuo at a Pressure of 100 to 20 mbar. In this basic mix are depending on the desired one Composition of (A) and (C) containing sub-mixtures further Components such as the component (D), (E) and (F) and optionally so-called non-reinforcing filler (C) expedient between 10 to 120 minutes at 10-160 ° C mixed. This results, for example, a partial mixture (1). Another part mix (2) receives by mixing the hardener (B) with the basic mixture. Possibly can about that In addition, the components (E) and (F) and possibly. So-called non-reinforcing filler (C) expedient between 10 to 60 minutes at 10-160 ° C be mixed. By combining the sub-mixtures (1) and (2) the reactive, sprayable Obtained silicone composition.

In a preferred embodiment of the process, the addition-crosslinking, sprayable silicone rubber mixtures are placed over the Production of at least two partial mixtures (1) and (2) ago, the more but not all of the components (A) to (F).

The preferred division into partial mixtures serves for better handling and storage. In which one by division of the reactive and catalyzing Components containing the components (A) to (F), the reaction of these components together until just before unification of all Components can be postponed before mixing and spraying.

to Production of unreacted partial mixtures becomes, for example a partial mixture (1) consisting of the components (A), (C) and (D) and optionally (F), and a part mixture (2) consisting at least from components (B) and optionally (F), by Mixing produced. For the sake of one appropriate handling is the sub-mixture (2) of the components (A), (B), (C), (E) and optionally (F) mixed.

Basically all possible Partial mixtures for a longer one Can be used for storage, as long as the component (A), (B) and (D) not present simultaneously in a partial mixture. Therefore separates one expediently the Component (B) and (D) when (A) is present at the same time or separates (B) and (A) if at the same time (D) in the same sub-mixture is present.

Of the Component (D) may be more or less beneficial in each of the Components are held, if not at the same time with each other reacting components (A), (B) are present side by side. The inhibitor (E) may be present in any part mixture, preferred is the combination in a part mixture with (B).

In order for the silicone composition used in the present invention to have sufficient sprayability, the viscosity immediately after mixing the above-described partial blends without catalyst component (D) is preferably less than 40 Pa.s (25 ° C.) at a shear rate gradient D = 10 s ^-1 .

The aforementioned viscosity of the total mixture implies that the viscosity of each of the above-described part mixtures (1) and (2) may be less than or equal to 40 Pa.s (25 ° C) at a shear rate gradient D = 10 s ^-1 , as far as the total mixture of (1) and (2) has less than 40 Pa · s (25 ° C) at a shear rate gradient D = 10 s.

In a further preferred embodiment the method according to the invention is said silicone composition above 0 ° C until a maximum pressure of about 200 bar, more preferably a maximum of 100 bar, even more preferably 5-40 bar, sprayable.

In a further preferred embodiment the method according to the invention the silicone composition is above 15 ° C, preferably within 3 hours, curable i.e. until a tack-free surface is obtained. Tack-free means, that one on the surface curing Cast resin can be separated.

In a further preferred embodiment of the method according to the invention, the silicone composition has a t ₁₀ value of 30 to 400 s at 30 ° C., measured in a vulcanameter according to DIN 53 529.

In a further preferred embodiment the method according to the invention For example, the silicone composition is substantially free of solvents. "Essentially free of solvents "within the meaning of the invention means that the silicone composition is less than 5% by weight, preferably less than 2% by weight, more preferably less than 1% by weight Solvents in particular organic solvents, contains. "Organic solvents" closes all carbonaceous solvents, excluding silicon-containing compounds.

• (A) mindestens ein alkenylgruppenhaltiges Polyorganosiloxans mit einem Viskositätsbereich von 0,025 und 40 Pa·s (25°C; Schergeschwindigkeitsgefälle D = 1 s^-1),
• (B) mindestens ein Polyorganohydrogensiloxan,
• (C) gegebenenfalls einen oder mehrere Füllstoffe,
• (D) mindestens einen Hydrosilylierungskatalysator,
• (E) gegebenenfalls einen oder mehrere Inhibitoren,
• (F) gegebenenfalls weitere Hilfsstoffe.

in einem Transfer-Formgießverfahren zur Herstellung einer Trennmembran.The invention further relates to the use of a preferably above 0 ° C with up to a pressure of at most 200 bar, more preferably at most 100 bar, more preferably sprayable 5-40 bar, silicone composition comprising:

• (A) at least one alkenyl group-containing polyorganosiloxane having a viscosity range of 0.025 and 40 Pa · s (25 ° C., shear rate gradient D = 1 s ^-1 ),
• (B) at least one polyorganohydrogensiloxane,
• (C) optionally one or more fillers,
• (D) at least one hydrosilylation catalyst,
• (E) optionally one or more inhibitors,
• (F) optionally further auxiliaries.

in a transfer molding method for producing a separation membrane.

The Invention further relates to a method for producing a Separating membrane by spraying the silicone composition defined above at least once on a carrier and the Trennmembran available by this method. "unique Spraying "means you sprayed in a single operation and without layered Structure hardens. This is preferred according to the invention, although it is possible is, after curing the first layer to repeat this process once or several times. The invention further relates to the use of the resulting separation membrane in a transfer molding process.

The Method allows the production of separation membranes with a wall thickness from 1 to 30 mm, preferably 3 to 12 mm, more preferably 3 to 6 mm.

The silicone mixtures cured according to the conditions mentioned in the example should have at least the following rubber-mechanical properties:
Hardness DIN 53505 from 15 to 50 ° Shore A, elongation at break DIN 53504 at least 200% and tensile strength at least 1.5 N / mm ² .

example 1

To prepare a basic mixture containing silica, 1120 g of a linear vinyl-stopped polydimethylsiloxane having a viscosity of 10 Pa.s at 25 ° C. were initially charged as component (A) with 0.046 mmol / g of vinyl in a dissolver, and 150 g of hexamethyldisilazane as water repellent (C), 10 g of 1,3-divinyltetramethyldisilazane as a reactive hydrophobing agent (C), and mixed in 55 g of water. Then were gradually mixed 560 · g fumed silica having a BET surface area of 300 m ² / g as component (C). The mixture was heated to about 90-100 ° C and refluxed for one hour. Thereafter, the volatiles were evaporated under vacuum and the mixture was diluted with 250 g of a vinyl end-stopped polydimethylsiloxane having the viscosity of 10 Pa · s of component (A).

Partial mixture (1)

In a dissolver, 268 g of the previously prepared masterbatch were mixed with 230 g of a linear vinyl-stopped polydimethylsiloxane (A) having a viscosity of 1 Pa.s at 25 ° C. with a vinyl content of 0.046 mmol / g and 2.0 g of a platinum catalyst as component ( D) mixed with 1 wt.% Pt as the Pt ⁰ complex with 1,3-divinyltetramethyldisiloxane. This platinum catalyst was prepared according to US 3,715,334 Example 5 and diluted with a linear vinyl end-stopped polydimethylsiloxane viscosity of 1 Pa · s at 25 ° C (component (A) with 0.122 mmol / g vinyl), the initial concentration was about 22 wt.% Pt. The mixture was deaerated in vacuo at 20 mbar. The viscosity of the sub-mixture (1) was determined by a cone-and-plate viscometer at a shear rate of D = 10 s ^-1 , which was 12.5 Pa · s at 25 ° C.

Partial mixture (2)

In a dissolver, 268 g of the above-prepared masterbatch with 206 g of a linear vinyl end-stopped polydimethylsiloxane having the viscosity of 1 Pa · s at 25 ° C as Komponenet (A), 20 g of a linear SiH endstopped polydimethylsiloxane as component B1) having a SiH content of 1.4 mmol / g and 6.5 g of a polydimethylsiloxane (B2) as a crosslinking agent of the type QM ^H _x with a SiH content of 9.3 mmol / g mixed. The mixture was deaerated in vacuo. The viscosity was determined with a cone-and-plate viscometer at a shear rate of D = 10 s ^-1 , which was 9.8 Pa · s at 25 ° C.

to Accurate determination of the reaction rate was performed in a rheometer MDR 2000 performed by Alpha Technologies at a chamber temperature of 30 ° C, in the sub-mixtures (1) and (2) at about 30 ° C in a Two-chamber cartridge filled, This with the help of a two-chamber dosing gun on a short static mixer directly into the at 30 ° C tempered measuring chamber of the rheometer splashed and immediately with the Measurement started (see Table 1). The measuring time was 30 minutes.

Tab. 1 Crosslinking rate of Example 1

Example 2

to Determination of the mechanical properties were 200 g of the sub-mixture (1) is added with 40 mg of the inhibitor dimethyl maleate and then mixed with 200 g of the sub-mixture (2). The mixture was in the Vacuum vented at 20 mbar, in a test plate form (2 mm thick test plates) and poured under Pressure (60 bar) for 10 minutes at 170 ° C cured (see Table 2).

Tab. 2 Rubber mechanical properties of Example 2

Example 3

The Partial mixture (1) and (2) of Example 1 were in a temperature-controlled Two-component system with the help of barrel pumps one stepless fed to adjustable gear pumps, which are the sub-mixtures at a pressure of up to 150 bar via hose lines in one dosed static-dynamic mixer. This one was on the short way connected with a spray attachment. About pressure change could the order quantity to be controlled. The reactive Mixture of the sub-mixtures (1) and (2) was on a rigid Mother mold of polyurethane sprayed to the separation membrane of the invention manufacture. The application was carried out at a temperature of 24 ° C in one Operation to layer thicknesses between 5 and 15 mm. The sprayed mass did not run off the vertical parts of the mold and cured quickly out. For the application was needed 15 minutes. The working pressure at the Spray nozzle was about 15 bar. The silicone separation membrane could take less than 30 minutes be removed from the rigid mold.

These Separating membrane came as an elastic silicone cover for the "Resin Transfer Molding "process to Commitment. This was a mold consisting of a rigid mother mold made of polyurethane (outer mold) and the flexible separation membrane made of silicone elastomer. The separation membrane was already in networking with suitable intake openings been provided. The mother mold contained a release agent. The mold gap contained a fiberglass braid, was used to maintain the Vacuum sealed and by applying a vacuum with an unsaturated Polyester resin incl. Hardener filled. Then the polyester resin was sucked in and thereby the glass fiber impregnated with resin. After curing of the polyester, the silicone cover was removed and again be used.

The Transparency of the separation membrane allowed the control of the bubble-free Filling. In this way could successively several glass fiber reinforced parts made of polyester resin, here a special body part with dimensions approx. 3 × 200 × 300 cm be prepared and demoulded without error.

Claims (21)

A process for producing resin moldings by a transfer process comprising the following steps: a) providing a mother mold, b) preparing a separating membrane by spraying a carrier material with a curing silicone composition, c) assembling the mother mold and the separating membrane obtained in step a) Creation of a cavity between the mother mold and the separating membrane, d) optionally introducing reinforcing materials into said cavity, e) optionally applying a vacuum to the cavity, f) filling the cavity with a curable resin composition, j) curing the resin composition, k) Removing the separation membrane; and l) demolding the resin molding from the parent mold, characterized in that said sprayable, curable silicone composition comprises: (A) at least one alkenyl group-containing polyorganosiloxane having a viscosity range of 0.025 and 40 Pa.s (25 ° C; igkeitsgefälle D of 1 s ^-1), (B) at least one polyorganohydrogensiloxane, (C) optionally one or more fillers (D) at least one hydrosilylation catalyst, (E) optionally one or more inhibitors, and (F) optionally further auxiliaries. The method of claim 1, wherein said silicone composition at least one reinforcing filler contains. The method of claim 1 to 2, wherein the reinforcing filler is selected from hydrophobic fumed silicas having a BET surface area of at least 200 m ² / g. A process according to any one of claims 1 to 3, wherein the polyorganohydrogensiloxane (B) at least one polyorganohydrogensiloxane having two Si-H groups per molecule and at least one polyorganohydrogensiloxane having more than two Si-H groups per molecule having. A process according to any one of claims 1 to 4 wherein said silicone composition comprises: (A) 100 parts by weight of at least one alkenyl group-containing polyorganosiloxane having a viscosity range of 0.025 and 40 Pa · s (25 ° C, shear rate D of 1 s ^-1 ), (B) from 0.1 to 200 parts by weight of at least one polyorganohydrogensiloxane, (C) optionally from 1 to 100 parts by weight of one or more fillers, (D) from 0.5 to 1000 ppm of at least one hydrosilylation catalyst calculated as metal based on the amount of components (A) to (C), (E) optionally from 0.0001 to 2% by weight of one or more inhibitors, based on the amount of components (A) to (C), (F) optionally further auxiliaries. A method according to any one of claims 1 to 5, wherein the component (A) said silicone composition of two or more alkenylgruppenhaltigen Polyorganosiloxanes exists. A method according to any one of claims 1 to 6, wherein the component (D) containing hydrosilylation catalyst, at least one metal, the selected is selected from the group consisting of Pt, Pd, Rh, Ni, Ir or Ru. The method of claim 7, wherein the hydrosilylation catalyst in metallic form, in the form of a complex compound and / or is used as a salt. A method according to any one of claims 1 to 8, wherein the component (D), the hydrosilylation catalyst, in an amount of 0.5-1000 ppm calculated as metal based on the weight of the components (A) to (C) is present. A method according to any one of claims 1 to 9, wherein the component (E), selected is selected from the group consisting of alkynols and vinyl siloxanes. A method according to any one of claims 1 to 10, wherein the total alkenyl content of component (A) greater than 0.035 mmol / g, the chain extender (B1) is measured so that after deduction of its molar SiH content from the alkenyl content of component (A) mathematically 0.08 to 0.02 mmol / g Alkenyl of component (A) remain and the crosslinker (B2) so is measured that the molar ratio of the total amount of Si-H of (B1) and (B2) to the total amount of Si-alkenyl is 1.1 to 1.5 to 1. A method according to any one of claims 1 to 11, wherein the silicone composition by mixing at least two subcomponents directly before the spray job will be produced. The method of claim 12, wherein at least two Subcomponents that do not simultaneously contain components (A), (B) and (D) are mixed. A method according to any one of claims 12 to 13, wherein the viscosity of the sprayable silicone composition without catalyst component (D) obtained immediately after the blending together of the two blends is less than 40 Pa.s (25 ° C) at a shear rate gradient D = 10 s ^-1 , A method according to any one of claims 1 to 14, wherein the silicone composition is curable above 15 ° C. A method according to any one of claims 1 to 15 wherein the silicone composition a t10 value of 10 to 400 s at 30 ° C measured according to DIN 53 529 having. A method according to any one of claims 1 to 16, wherein the silicone composition essentially free of solvents is. Use of a silicone composition which can be sprayed above 0 ° C comprising: (A) at least one alkenyl group-containing polyorganosiloxane having a viscosity range of 0.025 and 40 Pas (25 ° C, shear rate gradient D = 1 s ^-1 ), (B) at least one polyorganohydrogensiloxane, (C) optionally one or more fillers, (D) at least one hydrosilylation catalyst, (E) optionally one or more inhibitors (F) optionally further auxiliaries. for producing a separation membrane in a transfer molding method. Process for the preparation of a separation membrane by at least once spraying the silicone composition defined in claim 1 on a support. Separating membrane, obtained according to claim 19. Use of the separation membrane according to claim 20 in a transfer molding process.