NO890654L - Aqueous silicone dispersion and silicone elastomers made therefrom. - Google Patents

Description

The present invention relates to an aqueous dispersion

of silicone which can be cross-linked into an elastomer by removing water.

Patent document US-A-2 891 920 describes a method for the emulsion polymerization of polydiorganosiloxane using an acidic or basic catalyst in the presence of anionic, cationic or non-ionic surfactants. The patent teaches that the obtained emulsions are stable during storage and are used after the addition of fillers for the production of paints which, when water is removed, provide a continuous coating.

Patent document US-A 3,294,725 describes in particular the use of dodecylbenzenesulfonic acid for the emulsion polymerization of polydiorganosiloxanes. The patent document teaches that in order to obtain stable emulsions it is desirable to regulate the pH in these emulsions to a value of approximately 7. The patent document teaches that an elastomer coating can be obtained from these neutralized emulsions, to which colloidal silica and a polyalkylene silane have been added.

The teaching in patent document US-A 3,360,491 corresponds to patent document US-A 3,294,725 except that the dodecylbenzene sulfonic acid is replaced with hydrogen lauryl sulfate.

Patent document US-A 3,355,406 describes, among other things, a silicone latex comprising: a colloidal aqueous suspension of an a,w (di-hydroxy)polydiorganosiloxane,

a filler which necessarily contains a silsesquioxane in the form of a colloidal suspension,

a catalyst selected from mineral acids, strong bases, dialkyltin diacylates and organic or

inorganic peroxides.

Patent document US-A-3 697 469 describes a special method for emulsion polymerization of poly-:diorganosiloxanes and indicates the possibility of adding colloidal silica and a tin salt to this emulsion to obtain an elastomer coating by evaporation of water.

Patent document FR-A-2 110 358 describes a silicone emulsion at a pH between 6.5 and 9 and which cross-links into an electrically conductive elastomer by evaporation of water by incorporating "carbon black". The emulsion, which contains, among other things, a tin salt and a polyalkyloxysilane, is not stable when stored and must therefore be stored in two separate containers (two-component emulsion).

Patent documents US-A-4,221,688, US-A-4,244,849 and FR-A-

2,463,163 discloses silicone emulsions which are stable upon storage and comprise: an emulsion of an a,w (dihydroxy)polydiorganosiloxane polymer which is anionically stabilized,

a siliceous filler,

a stannous salt, and

possibly a non-reinforcing filler.

The siliceous filler may be a colloidal silica (US-A-4 221 688), sodium silicate (US-A-4 244 849) or an amorphous powdered silica (FR-A-2 463 163).

With regard to aqueous emulsions (dispersions) known from the past, these three patent documents teach on the one hand that in order to obtain a one-component emulsion which is stable during storage, one must preserve the emulsion at an alkaline pH above 8.5 or 9, preferably above 10, and on the other hand, that a tin salt is incorporated into the emulsion in order to shorten to a few days the step of maturing the emulsion which is necessary to obtain an emulsion which is capable of cross-linking.

If the regulation to an alkaline pH value of the emulsion has allowed to improve the storage stability compared to known emulsions which are stored at a neutral or basic pH, it has been shown that the elastomer obtained after evaporation of the water exhibits with time a significant modification of its mechanical properties and particularly with regard to the extension, which can represent a disadvantage.

This modification of the mechanical properties is for

the expert not a surprising phenomenon. It is actually well known that the silicone polymers depolymerize in an alkaline environment into fractions with a low molecular mass, including also a monomer fraction.

These silicone chain fractions naturally lead to the modifications of the mechanical properties of the elastomer with time, i.e. during its aging.

Furthermore, known filled silicone emulsions, stored at acidic or neutral pH, have at least one of the following disadvantages: they are not stable during storage when arranged in a simple packaging (one-component mixture),

they have a long curing time to elastomer,

they are not thixotropic,

they only stick easily to common surfaces.

In the following, percentages and parts by weight are by weight unless otherwise stated.

An aim of the present invention is to provide an aqueous silicone dispersion which can be cross-linked into an elastomer by removing water, at normal temperature, which does not present the disadvantages of the known emulsions, or only to a very small extent.

A further object of the present invention

is to provide a storage-stable silicone dispersion of the above type which cross-links correctly and sufficiently rapidly into an elastomer upon removal of water at ordinary temperature, the elastomer formed retaining its mechanical properties during its aging.

A further object of the invention is to provide a silicone dispersion of the above-mentioned type where the ripening step can be carried out at a lower temperature (20-60°C) and during a time of less than 48 hours.

A further object of the invention is to provide a silicone dispersion of the above-mentioned type which leads to an elastomer which, among other things, has an improved flame resistance.

A further object of the invention is to provide a silicone dispersion of the above type which leads to an elastomer which has a satisfactory adhesion to various supports and in particular to glass, concrete or metals (steel, aluminium).

These and other purposes are achieved by the present invention, which relates to an aqueous silicone dispersion which cross-links into an elastomer by removing water under normal conditions, characterized in that it comprises:

(A) - 100 parts of an oil-in-water type emulsion

of a oi, uj(dihydroxy) polydiorganosiloxane stabilized

by means of at least one surface-active agent selected from anionic and non-ionic surface-active agents and mixtures thereof,

(B) - 0.1 to 15 parts calculated as dry matter, of an alkali metal or alkaline earth metal organosilicone

in aqueous solution,

(C) - 5 to 250 parts of a non-silicon mineral filler, (D) - 0.01 to 3 parts of a catalytic tin compound,

in that this dispersion has a pH above 8.5, preferably between 9 and 12, and a dry matter content of at least 40%.

The a,u-(dihydroxy)polydiorganosiloxanes must have a viscosity of at least 100 mPa.s at 25°C, preferably at least 50,000 mPa.s.

It is actually at viscosities above 50,000 mPa.s that an elastomer is obtained which has a suitable collection of mechanical properties, particularly with regard to Shore A hardness and elongation.

Furthermore, at higher viscosity, the mechanical properties will be maintained when the elastomer ages.

The preferred viscosities of the invention are between 50,000 and 1,500,000 mPa.s at 25°C.

The organic radicals in the a,w-(dihydroxy)polydiorgano-polysiloxanes are monovalent hydrocarbon radicals containing up to 6 carbon atoms, optionally substituted with cyano or fluoro groups. The substituents generally used because of their availability in industrial products are methyl, ethyl, propyl, phenyl, vinyl and 3,3,3-trifluoropropyl. In general, numerically at least 80% of these radicals are methyl radicals.

Within the framework of the present invention, it is particularly preferred to use a,w-(dihydroxy)polydiorganosiloxanes produced by the anionic polymerization method described in the above-mentioned patents US-A-2 891 920 and in particular US-A-3 294 725 (cited as a reference) . The obtained polymer is stabilized anionically by means of a surface-active agent which, in accordance with the teaching according to US-A-3 294 725, is preferably an alkali metal salt of an aromatic hydrocarbon sulphonic acid, the free acid also acting as a polymerization catalyst.

The preferred catalyst and surfactant is dodecylbenzenesulfonic acid and its alkali metal salts, especially its sodium salt. Other anionic or non-ionic surfactants can optionally be added. However, this addition is not necessary since, according to the teachings of US-A-3,294,725, the amount of anionic surfactant resulting from neutralization of the sulfonic acid is sufficient to stabilize the polymer emulsion. This amount is generally below 3% and preferably 1.5% by weight of the emulsion.

The process of emulsion polymerization is particularly interesting as it allows direct obtaining of the emulsion (A). Furthermore, this method allows without difficulty to obtain emulsions (A) of a,oj (dihydroxy(polydiorganosiloxane) with very high viscosity.

For the production of emulsion (A), one can likewise start from , -(dihydroxy)polydiorganosiloxane which has already been polymerized, by bringing this into an aqueous emulsion and stabilizing the emulsions with the help of an anionic and/or non-ionic surfactant using of a method which is well known to the person skilled in the art and described in detail in the literature (see e.g. patent documents FR-A-2 064 563, FR-A-2 094 322,

FR-A-2 114 230 and EP-A-169 098).

In this method, by simple stirring, the di-hydroxypolydiorganosiloxane polymers are mixed with an anionic or non-ionic surface-active agent, the latter can be in an aqueous solution, and then water is added if necessary and the entire mixture is converted into a fine and homogeneous emulsion when carried out in a conventional colloid mill.

The resulting colloid product is then diluted with

a suitable amount of water and an emulsion (A) is then obtained which is stabilized by means of an anionic or non-ionic surfactant and which is stable on storage.

The amount of anionic and nonionic surfactant used is that which is usually used to carry out the emulsification process, particularly as described in the above-mentioned patents and in patent US-A-2 891 920.

Within the scope of the present invention, the preferred anionic surfactants are the salt of an alkali metal of an aromatic hydrocarbon sulfonic acid and the preferred nonionic surfactants are polyoxyethylenated alkylphenols. These non-ionic surface-active agents are of course the same which can optionally be added to the emulsions (A) obtained by emulsion polymerization as indicated above.

The emulsion (A) produced by emulsion polymerization or by emulsifying the silicone polymer is in the form of an emulsion of oil in water and preferably has a solids content of over 45% by weight.

For 100 parts of emulsion (A), 0.1 to 15 and preferably 0.5 to 5 parts, calculated as dry matter, of an alkali metal or alkaline earth metal organosilicone are incorporated in aqueous solution.

These alkali metal or alkaline earth metal organo-siliconates are known products, most of which are commercially available. The most common are sodium or potassium methyl silicones with approximately 30 to 60% solids content.

The alkali metal organosilicones can be prepared, e.g.

by hydrolysis of corresponding organosilanes with three hydrolyzable groups, such as halogen atoms or alkoxy radicals, by means of a solution of the obtained product in a solution of an inorganic strong base, in a quantity ratio such that there is at least one base per silicon atom (see, for example, US-A-2,441,422, US-A-2,441,423 and US-A-2,507,200).

A further component of the dispersion according to the invention is the addition of 5 to 250 and preferably 10 to 200 parts of a semi-reinforcing mineral filler or ordinary filler (C).

The fillers (C) have a grain size generally between 0.001 and 300 fam and a BET surface area below 100 m 2 /g.

Examples of fillers (C) that can be used alone or in a mixture are carbon black, titanium dioxide, aluminum oxide, hydrated aluminum oxide, expanded vermiculite, non-expanded vermiculite, calcium carbonate, zinc oxide, mica, talc, iron oxide, barium sulphate and slaked lime.

The fillers (C) are introduced into the emulsion in the form of dry powder, e.g. by simple mixing.

In one embodiment of the invention, it has been demonstrated that if the filler (C) mainly consists of only one filler selected from hydrated aluminum oxide, expanded vermiculite, non-expanded vermiculite with a content of 5 to 250, preferably 50 to 200 parts for 100 parts emulsion (A), an elastomer is obtained with a particularly good flame resistance which cannot be obtained with the other categories of the aforementioned fillers (C),

in particular with aluminum oxide or non-hydrated aluminum oxide. One can likewise incorporate ceramic fibers or aramid fibers corresponding to the teaching in EP-A-212 827.

The component (D) is a catalytic tin compound generally an organotin salt introduced preferably in the form of an aqueous emulsion. The usable organotin salts are particularly described in the work NOLL, Chemistry and Technology of Silicones, Academic Press (1968), p. 337.

The reaction product of a tin salt, in particular a tin dicarboxylate with ethyl polysilicate, can also be used as a catalytic tin compound, as described in patent US-A-3 862 919.

You can also use the reaction product between an alkyl silicate or an alkyl trimethoxy silane with dibutyl tin diacetate as described in patent document BE-A-842 305.

The preferred tin salts are tin bichelates

(EP-A-147 323 and EP-A-235 049), further diorganotin dicarboxylates and in particular dibutyl or dioctyl tin diversacetates (patent document GB-A-1 289 900), further dibutyl or dioctyl tin diacetate , dibutyl or dioctyl tin dilaurate. 0.01 to 3 and preferably 0.05 to 2 parts of organotin salt are used for 100 parts (A).

In one embodiment, a silicon-containing additive can be incorporated for 100 parts of emulsion (A)

(E) selected from sodium silicate (0.3 to 30 parts) and a reinforcing or semi-reinforcing siliceous

filler (1 to 150 parts).

These silicon-containing fillers are selected from colloidal silica, pyrolytic or precipitated silica or mixtures thereof. Pyrolytic silica is preferred. You can also use silicon-containing semi-reinforcing fillers such as diatomaceous earth and ground quartz.

For 100 parts emulsion (A) is the sum of the components

(C) + (E) under 300 parts.

Silica powders are well known and used in particular as

fillers in silicone elastomer compounds that can be vulcanized in the heat into a silicone rubber. These powders have an average particle size generally below 0.1 µm and a specific BET surface area above 50 m 2 /g, preferably between 150 and 350 m 2 /g.

Incorporation into the emulsion (A) of this silicon-containing additive (E), by any suitable means, in particular by stirring, considerably increases the viscosity of the emulsion (A) which will then acquire a paste character.

In accordance with the present invention, it has actually been found that the addition of this silicon-containing addition

(E) is sufficient to give the dispersion a more or less marked "thixotropic" character. The dispersion, taken

out e.g. from a storage container, adheres without flow to an even vertical substrate and hardens to elastomer by evaporation of water at ordinary temperature. A non-flowing emulsion can also be obtained by using calcium carbonate as filler (C) where the average particle diameter is below 0.1 µm. Of course, a slight heating (to approximately 40 to 80°C) of the mixture to accelerate the evaporation of water is not excluded in the context of the invention.

Various additives can optionally be added to the dispersion in accordance with the invention which allow the properties of the dispersions and the elastomers formed from the dispersions to be modified by removing water.

One can in particular incorporate an additive (F), chosen from among organotrimethoxysilanes, such as e.g. vinyl trimethoxysilane, alkyl silicates such as methyl silicate or ethyl silicate or their partial hydrolysis products, i.e. alkyl polysilicates such as methyl polysilicate and ethyl polysilicate with a content of 0.1 to 20 parts additive (F) for 100 parts emulsions (A). The additive (F) allows to improve the cohesion of the obtained elastomeric material after removing the water.

The organotrialkoxysilanes and alkyl silicates preferably correspond to the general formula:

wherein R is an alkyl radical of 1 to 4 carbon atoms,

R<1> is R or vinyl and a is 1 or 0.

Anti-fungal agents, anti-foam agents as well as thixotropic agents such as carboxymethyl cellulose, xanthan gum and polyvinyl alcohol can be mentioned as other examples of additives.

The dispersions in accordance with the invention can be used to form elastomeric silicone compounds, particularly in the construction industry.

These dispersions can also be used for encapsulating different pharmaceutical or phytosanitary principles in solid form (lozenges, tablets, pills, etc.), for impregnating bottle caps to close bottles for wine and spirits, for forming coatings on kitchenware and general coatings on objects in contact with foodstuffs (e.g. cake tins).

Known methods for coating can be used, and in particular methods with impregnation by ironing or by immersion, powder coating, coating using a fluidized layer and impregnation methods by immersion.

For coating bottle caps is a recommended method

an impregnation that consists of immersing the corks in the dispersion that moistens the cork surface after which the water evaporates.

The coating obtained represents 20 to 50 mg of elastomer for 100 cm 2 of cork surface. This layer facilitates the cork's sliding in the bottle neck when emptying the bottle and prevents liquid from flowing out between the bottle neck and the cork.

The dispersions in accordance with the invention can be prepared in the following way: One starts from an emulsion (A) prepared either by emulsion polymerization where one disposes of an emulsion stabilized with the help of an anionic and possibly a non-ionic surfactant, or by a method in which uses the emulsion of a,w-(dihydroxy)polydiorganosiloxane and disposes of an emulsion stabilized by means of an anionic and/or non-ionic surfactant.

First 0.1 to 15 parts organosilicate (B) and then 0.1 to 3 parts of the catalytic tin compound (D) and finally 5 to 250 parts filler (C) are mixed into 100 parts of this emulsion (A). Optionally, the silicon-containing additive (E) and the additive (F) are added to this mixture.

In general, a dispersion is obtained which directly has a pH above 8.5. If this is not the case or if you want to increase the pH, the pH is regulated by adding an acid or an inorganic or organic base.

As an organic base, primary amines such as diethylamine can be used. In a preferred embodiment of the invention, however, the pH is regulated to the desired value by means of an adapted amount of an inorganic base introduced in the form of an aqueous solution preferably selected from solutions of alkali metal or alkaline earth metal hydroxides such as caustic soda or caustic soda, solutions of calcium hydroxide and barium hydroxide. The alkali metal hydroxides and alkaline earth metal hydroxides can be introduced directly in a solid form like magnesium hydroxide.

The components (A), (B), (C), (D) and possibly (E) and

(F) is mixed in amounts so that the final dispersion has a solids content of more than 40%, preferably more than 60%,

but generally below 90%. The preferred pH range is between 9 and 12.

The dispersions according to the invention can be used as paint which can be cross-linked in a thin layer. They have then preferred a dry matter content between 40 and 70%.

To determine the dry matter content, 2 g of the dispersion is placed on an aluminum weighing pan and heated for 1 hour at 150°C in an oven with air circulation. After cooling, the aluminum bowl and the percentage of material present in relation to the original 2 g are reweighed to determine the dry matter content.

In a preferred embodiment, the dispersion according to the invention is subjected, after production, to a maturation step preferably at a pH above 8.5, optionally by heating at a temperature from 20 to 60°C for a time generally of at least 1 hour and generally up to 72 hours.

At a higher ripening temperature, ripening occurs faster with a correspondingly shorter ripening time.

This ripening step allows, after removal of the water, to obtain an elastomer with immediately good mechanical properties.

In what follows, percentages and partial statements are based on weight, unless otherwise stated.

EXAMPLE 1:

An emulsion (A) of a,w-(dihydroxy)polydimethylsiloxane oil is prepared by emulsion polymerization in the presence of free dodecylbenzenesulfonic acid and its sodium salt.

The oil contained in the emulsion has a viscosity of 10^ mPa.s at 25°C. The emulsion (A) obtained contains for 100 parts of emulsion 1.5 parts of the sodium salt of dodecylbenzenesulfonic acid (DBSBa) and has a solids content of 58%.

To 173 parts of emulsion (A) are added and homogenized at 25°C first 7 parts of potassium methylsiliconate with 40% dry matter content and then 2.6 parts of an emulsion based on tin containing 40% by weight of dioctyl tin dilaurate (D).

After 10 min. homogenization, 150 parts of CaCO^ with an average grain size of 5 µm are added.

The final dispersion has a solids content of 70% and directly has a pH above 9.

With this liquid dispersion, a maturation is carried out at 25°c for 48 hours.

Films (foils) are produced by spreading the dispersion, possibly after ripening, on a flat surface and allowing the water to evaporate at normal temperature.

On dried test pieces, after 7 days at normal temperature, the average mechanical properties are measured as follows: Shore A hardness (DSA) according to standard ASTM-D-2240,

breaking strength (R/R) according to standard AFNORT-T 46 002 corresponding to standard ASTMD 412, in mPa.s,

elongation at break (A/R) in % according to standard AFNOR-T 46 002,

modulus of elasticity (ME) at 100% elongation according to standard AFNOR-T 46 002.

The composition of the dispersion and the mechanical properties that are achieved are summarized in table 1.

The obtained elastomer has good adhesion to glass, concrete and aluminium.

To assess the adhesion, a layer of aqueous dispersion with a thickness of 4 mm is deposited on a support of glass or concrete. After 12 days, the adhesion of the formed elastomer is assessed by manual removal of the layer. The adhesion is good on the two substrates as the layer cannot be removed manually from the carrier.

EXAMPLE 2:

The procedure in example 1 is followed exactly, except: the surfactant used is a mixture with 50/50 weight basis dodecylbenzenesulfonic acid (ADBS)

and a 70/30 weight-based mixture of polyoxyethylenated nonylphenols, one of which has 10 units of OCI^CI^

and the other 20 units of OCH2CH2(NPP),

the viscosity of the oil is 85,000 mPa.s, with solids content in the emulsion (A) 58%,

the calcium carbonate is replaced by means of hydrated aluminum oxide with an average grain size of 100 µm.

The obtained dispersion flows.

The composition of the dispersion and the mechanical properties achieved are summarized in table 1.

The elastomer obtained has a good adhesion to glass, concrete and aluminum and has a remarkable self-extinguishing character.

EXAMPLE 3:

The working method in example 1 is followed exactly, except: the viscosity of the oil is 85,000 mPa.s, and the solids content in the emulsion (A) is 58%,

the 150 parts of calcium carbonate with an average grain size of 5 µm are replaced by 150 parts of calcium carbonate with an average grain size of 0.08 µm.

The obtained dispersion is non-flowing.

The composition of the dispersion and the mechanical properties achieved are summarized in table 1.

The obtained elastomer has good adhesion to glass, concrete and aluminium.

With three other groups of dried samples, theirs is measured

A/R, DSA and ME, respectively. after natural aging for 5 months.

at normal temperature (20°C), after accelerated aging in a ventilated drying cabinet for 7 days at 50°C and after accelerated aging for 42 days at 50°C.

The results obtained are summarized in table 2.

EXAMPLE 4:

The working method in example 1 is followed exactly, except: the reaction product between 1 mol of dioctyltin oxide and 1 mol of versatic acid is used as a tin catalyst with the removal of the water formed. The reaction product is brought into emulsion. This emulsion contains 8.55% by weight tin metal,

150 parts of calcium carbonate with an average grain size of 5 µm are replaced by 150 parts of calcium carbonate with an average grain size of 0.08 µm.

The obtained dispersion is non-liquid. The composition of the dispersion and the mechanical properties achieved are summarized in table 1.

The obtained elastomer has good adhesion to glass, concrete and aluminium.

With a group of dried samples, DSA, R/R and A/R are measured after aging for 28 days at 50°C.

The values found are: DSA: 25, R/R: 0.97 MPa and

A/R: 428%.

EXAMPLE 5:

The working method in example 1 is followed exactly, except: the silicone oil in emulsion (A) has a viscosity of 10^ mPa.s at 25°C and a solids content of 58.6%,

150 parts of calcium carbonate with an average grain size of 5 pm are replaced by 100 parts of calcium carbonate with an average grain size of 0.08 pm.

The obtained dispersion is non-flowing.

The composition of the dispersion and the mechanical properties achieved are summarized in table 1.

The obtained elastomer has good adhesion to glass, concrete and aluminium.

With a group of dried samples, DSA, R/R and A/R are measured after natural aging for 8 months. at normal temperature (20°C).

The values found are: DSA: 16, R/R: 0.88 MPa and A/R: 428%.

Claims (13)

1. Aqueous silicone dispersion which cross-links into an elastomer by removing water under normal conditions, characterized in that it contains, by weight: (A) - 100 parts by weight of an oil-in-water type emulsion of a,w-(dihydroxy)polydiorganosiloxane stabilized by means of a surfactant selected from anionic and nonionic surfactants and their mixtures, (B) - 0.1 to 15 parts by weight, calculated as solids content, of an alkali metal or alkaline earth metal organosilicone in aqueous solution, (C) - 5 to 250 parts by weight of a non-silicon-containing inorganic filler, (D) - 0.01 to 3 parts by weight of a catalytic tin compound in that the dispersion has a pH above 8.5 and a solids content of at least 40%. 2. Dispersion as stated in claim 1, characterized in that the tin salt (D) is in the form of an aqueous emulsion. 3. Dispersion as stated in claim 1 or 2, characterized in that the emulsion (A) has a solids content of at least 45% by weight. 4. Dispersion as specified in one or more of claims 1-3, characterized in that the filler (C) is selected from among hydrated alumina, alumina, calcium carbonate, expanded vermiculite, non-expanded vermiculite, carbon black, zinc oxide, titanium dioxide, mica, talc, iron oxide, barium sulfate and slaked lime. 5. Dispersion as stated in claim 4, characterized in that the calcium carbonate has an average particle diameter below 0.1 pm. 6. Dispersion as specified in one or more of the preceding requirements, characterized in that it contains: (A) : 100 parts emulsion of the oil-in-water type of an a, a)-(dihydroxy)polydiorganosiloxane with viscosity at 25°C between 50,000 and 1,500,000 mPa.s and which is stabilized by means of a surfactant selected among an alkali metal salt or of an aromatic hydrocarbon sulphonic acid and polyoxyethylenated alkylphenols, (B) : 0.5 to 5 parts of an organosilicone, (C) : 50 to 200 parts of an inorganic filler, (D) : 0.05 to 2 parts of a diorganotin dicarboxylate, in that the emulsion has a pH between 9 and 12 and a solids content of at least 60%. 7. Dispersion as specified in one or more of the preceding requirements, characterized in that it further contains for 100 parts of emulsion (A) a silicon-containing additive (E) selected from sodium silicate (0.3 to 300 parts), and a reinforcing or semi-reinforcing silicon-containing filler (1 to 150 parts) with the condition that for 100 parts (A) the sum of the parts (C) + (E) is less than 300 parts. 8. Dispersion as specified in one or more of the preceding requirements, characterized in that it further contains for 100 parts of emulsion (A) 0.01 to 20 parts by weight of an additive (F) selected from among organotrialkoxysilanes, alkyl silicates and alkyl polysilicates. 9. Method for producing a silicone dispersion as specified in one or more claims 1-8, characterized in that 1) - the emulsion (A) and the organosilicone (B) are mixed, 2) - the non-silicon-containing filler (C) and the catalyst (D) and possibly the silicon-containing additive (E) and the additive (F) are added, 3). 10. Method as stated in claim 9, characterized in that the obtained dispersion, before its treatment with the exclusion of air, is subjected to a maturation step at a temperature between 20 and 60°C during a time of at least 1 hour. 11. Elastomers obtained by curing by evaporation of water from a dispersion as specified in one or more of claims 1 to 8. 12. Use of an aqueous dispersion as stated in one or more of claims 1-8 for impregnation and coating of pharmaceutical or phytosanitary principles and for establishing a coating on objects in contact with foodstuffs. 13. Application as stated in claim 12, characterized in that the said objects in contact with foodstuffs are bottle caps for filling bottles for wine and spirits.