DE1018221B - Stabilizer against the effects of heat for organopolysiloxanes condensed with the help of alkali compounds - Google Patents

Description

Stabilizer against the action of heat for using Organopolysiloxanes condensed by alkali compounds The invention relates to Use of organic phosphorus compounds as a steel stabilizer against the action of heat for organopolysiloxanes condensed with the help of alkali compounds, For the production of various organopolysiloxane oils and those curable to form elastomers organopolysioloxanes with higher molecular weight from lower organopolysiloxanes or mixtures of lower organopolysiloxanes, alkali compounds are used, such as alkali hydroxides, alkali metal alcoholates, alkali metal mercaptides, Alkali metal silanolates, as they are e.g. Described in U.S. Patent 2,587,636 are, alkali metal complexes of aromatic compounds, such as potassium complexes of naphthalene or anthracene, alkali metal complexes, as described in US Pat. No. 2,634,252, Alkali salts of organopolysiloxanes, such as the sodium salt of tetramethyldisiloxanediol according to U.S. Patent 2,634,284.

In the production of organopolysiloxane oils or rubbers, various alkaline catalysts or polymerizing agents are used to rearrange the siloxane bonds. It is therefore often desirable in the production of organopolysiloxane oils to break the chains of the organopolysiloxanes in order to improve the stability of the silicone oil. It is also customary to polymerize mixtures of different organosiloxanes, for example dimethylsiloxars of the formula (R2SiO) 1 with linear siloxanes of the formula In the formulas, R denotes a monovalent organic radical, for example a monovalent hydrocarbon radical, halogenated hydrocarbon radicals such as mono- or polychlorinated aryl radicals, m a number between 3 and 9, n an integer between 0 and 6. In this copolymerization, alkaline agents are used, to organopolysiloxanes with long chains of the formula where p is an integer between 6 and 200 or more. R can be in the above. Formula identical or different organic radicals; represent the above meaning. Organopolysiloxanes according to formula III are described, for example, in U.S. Patents 2,469,888, 2,469,890 and 2,599,984.

When using the alkaline catalysts mentioned at the outset, however, there are some disadvantages. It is believed that the rearrangement and polymerization of organopolysiloxanes, the alkali metal compound, especially potassium hydroxide, as a chain terminating agent in the form of a O-Si-O M radicals (M = alkali atom) acts, for example one O-Si-OK group.

Therefore, a polysiloxane is obtained in the reaction mixture which is relatively unstable at elevated temperatures. When the Reaction product, for example to volatile or low-boiling substances remove (temperatures of around 200 ° or more are required) the remaining potassium hydroxide or potassium salts (including the potassium silanolates) the stability of the organopolysiloxane is disadvantageous. The organopolysiloxanes with higher Molecular weights are broken down into reaction products with a lower molecular weight, d. H. that the yield of the higher molecular weight product is reduced.

It is also used in the production of organopolysiloxanes, those in the hardened, solid elastic state, d. H. in a silicone rubber, can be converted, often desirable, organopolysiloxanes with lower Molecular weight to products of higher molecular weight, which are usually extremely viscous and rubber-like substances are to be polymerized. These are with Fillers and optionally curing agents are added and then in the heat and deformed under pressure or used for coating at elevated temperatures and converted into hardened, firm, elastic products. During manufacture Such convertible organopolysiloxanes are also alkali compounds used. The removal of the low-boiling substances contained in the convertible organopolysiolanes Organopolysiloxanes have hitherto been extremely difficult and only with the use of special ones Precautions to avoid degradation of the organopolysiloxanes by residual ones Alkali compounds possible.

If an alkali compound remains in the convertible organopolysiloxane, the cured organopolysiloxane may decompose after a long time at temperatures of about 2500 or at temperatures of about 3000 after shorter Time.

To some extent you can. this restlic. hen. alkaline condensing agent can be removed by careful washing or neutralization. However is it is difficult, despite the utmost care, to remove the last traces of the alkali compound remove. Frequently, washing the neutralized product is also not possible remove all traces of the salts formed during neutralization. It can be increased at Temperatures a decomposition of the neutral salts occur, and there can be residues arise, the wiererum depolymerizing or degrading on the organopolysilioxane works.

It was now. found that the disadvantages mentioned are avoided, when in an organopolysiloxane previously treated with an alkali compound organic phosphorus compound or mixtures of organic phosphorus compounds be introduced that stabilize or soften it, for example. That with Organopolysiloxane treated with the alkali compound can contain either residues of alkali compounds, for example residues of alkali hydroxides, or reaction products of the organopolysioxanes with alkali compounds.

The organic phosphorus compound is associated with the alkali atom Alkali compound around, so that the depolymerizing or degrading effect of the alkali compound or their reaction products with the organopolysiloxane are reduced or eliminated will.

The mass obtained has improved at normal or elevated temperature Stability.

It is already known to use organic phosphorus compounds for improvement the heat resistance of silicone resins. For the production of such However, as is known, no alkali compounds are used, and it is known that silicone resins was therefore from the well-known addition of organic phosphorus compounds to silicone resins not foreseeing whether an addition of organic phosphorus compounds to organopolysiloxanes, which were condensed with the help of alkali compounds, an Nviflng at all would exercise. and possibly what an effect.

Under the term used in the description and claims "Organic phosphorus compounds" are to be understood as compounds that contain a phosphorus atom and an organic radical in association with others, usually in organic Contain elements occurring in phosphorus compounds, such as hydrogen, Oxygen, sulfur, selenium, alkali metal, halogen (including directly on carbon bound halogen), nitrogen. Numerous suitable for the purposes of the invention organic phosphorus compounds are in the book "Organophosphorus Compounds" by G. M. Kosolapoff, New York (1950). First requirement for eligibility of the organic phosphorus compounds (hereinafter also referred to as »alkali deactivating organic phosphorus compounds «) is that they are reactive to the above-described alkali compounds or their reaction products with organopolysiloxanes and the adverse effects of alkali compounds or their reaction products to reduce or improve the organopolysiloxane treated with alkali compounds. It is best to use non-toxic organic phosphorus compounds. It will Therefore, it is advisable not to use any organic phosphorus compounds that contain phosphorus contain bound halogen (e.g. chlorine). Finally, the organic phosphorus compounds should or the products formed in the reaction with the alkali compounds, the organopolysiloxane do not adversely affect. Organic phosphorus compounds suitable according to the invention are compounds of the general formulas a) (R °) l P O (o-phosphoric acid ester) b) R '(R O) 2 P 0 (organophosphorous acid ester) c) R Og P (metaphosphoric acid ester) d) R'P O (O H) 2 (organophosphorous acid) e) (RO) 2O (O) H (phosphorous acid ester) f) R P O., H2 (organo-phosphorous acid) in which R and R 'are the same or different organic residues, alkyl, cycloalkyl, aryl, aralkyl, alkaryl, alkenyl residues, such as vinyl, allyl, methallyl, crotyl radicals, and also monovalent hydrocarbon radicals with substituents inert towards the organopolysiloxane, for example halogen atoms, or nitro groups. The substituted radicals can, for example, chlorophenyl, Be chlorotolyl, chloroethyl radical.

Preferably, the organic phosphorus compound contains in the molecule at least one aryl or alkaryl radical, e.g. B. a phenyl or cresyl radical by Oxygen bound to phosphorus. The compounds mentioned above can be made by Replacement of the oxygen atom with sulfur or selenium, e.g. B. according to the formulas [(CaH5S) 3PSes (C6H.0) 8PSei.

The specific organic phosphorus compounds include: acidic esters of o-phosphoric acid, e.g. B. diethyl-o-phesphate, diphenyl hydrogen phosphate, Monostearyl-o-phosphate; also triphenyl phosphate, tricresyl phosphate, tri- (p-tert. butylphenyl) phosphate, tributyl phosphate, trioctyl phosphate, dibutylphenyl phosphate, Diphenyl phosphate, diphenyl butyl phosphite, triphenyl phosphite, phenyl phosphine, ethyl phosphine, Triphenyl thiophosphate, esters as described in dn. U.S. Patents 2,425,765, 2,453 167, 2,478,441 and 2,497,637. Examples of organic phosphorus compounds are also described in U.S. Patents 2,614,990 and 2,618,600. It organic esters of hypophosphoric acid are also known, e.g. B.

(R O), P (0) -0-P (0) (OR) 2, in which R has the meaning given above and which act in the desired way.

In addition to the organic phosphorus compounds described above, organic phosphorus compounds can also be used according to the invention which, in addition to organic radicals and a phosphorus atom, also contain metal atoms, according to the general formulas: c) (RO) 2P-OM 'd) ROP- (OM') 2 in which R is as defined above and M 'is a metal, e.g. B. calcium, barium, iron is.

Such organic phosphorus compounds are the salts of acidic phosphoric acid esters, such as calcium phenyl phosphate, calcium di (di-butyl phosphate), barium di (di-phenyl phosphate).

In the metal-containing organic phosphorus compounds described one or all of the oxygen atoms bound to phosphorus can be replaced by sulfur, Selenium or tellurium.

When using organic phosphorus compounds that contain the P-OH group, through. the reaction with the alkali compound or its reaction products with the organopolysioxane P-OM radicals formed (M = alkali metal atom). The removal of the metal atom with a degrading or depolymerizing effect can create silanol groups are formed, which do not have a degrading effect on the organopolysiolane. In order to achieve optimal results, an excess of the organic phosphorus compound containing a -POH group should be rented out.

The amount of organic phosphorus compound to be used can vary widely Extent and fluctuate depends on the special organic phosphorus compound used, the type of organopolysiloxane, the amount used in its manufacture or treatment of the organopolysiloxane used. the intended use of the organopolysiloxane and the calculated amount. of alkali compound or the reaction product, the in which organopolysioxane is present. When the amount of organic used Phosphorus compound at least 0.1 mole per mole in the siloxane. as alkali metal or as Alkali compound equivalent to existing alkali will give excellent results obtain.

However, a considerable excess of this can also be added up to about 3% or more based on the weight of the organopolysiloxane.

Larger amounts, e.g. B. from 5 to 200/0, based on the weight of the Organopolysiloxane, organic phosphoric acid ester of the formulas (RO) 3PO and (RO) 3P, in which R have the meaning given above; organic phosphorus compounds, in which all hydroxyl groups are esterified by R, can optionally be in the Intermediate or final stages of treatment are used .. Larger than for stabilization Required amounts of certain organic phosphorus compounds make elastomers curable organopolysiloxanes soft and set. their hardness so that they mixed with various fillers, pigments, dyes, hardeners, lighter, e.g. B. to be insulated conductors, spray.

Another advantage of using the organic phosphorus compounds consists in improving the storability and deformability of the convertible Organopolysiolxant. Those convertible into the hardened, solid, elastic state Organopolysiloxanes are extremely sensitive to moisture and behave different during processing, depending on the moisture content of the air.

By adding an organic phosphorus compound to one convertible organopolysiloxane obtained by polymerizing with an alkali compound has been produced, this sensitivity is reduced, and the formed Organopolysiloxane is stable in terms of viscosity and consistency in moist air. Is no organophosphorus compound present. so takes under the action of The viscosity of the polymer decreases, it becomes "soupy" and can be used then difficult to process. Due to the presence of organic phosphorus compounds, especially in amounts sufficient to soften, easier mixing is on Rubber mixing mills possible. It is therefore possible according to the invention, harder convertible polysiloxanes with less difficulty on mixing mills to process.

Certain, difficult to process, structure-forming fillers can. can now be used advantageously. Finally, hardeners, which are otherwise due to remnants of the Alka. liverbin, dungen or their connection with the siloxane will be ineffective, be used if the organic phosphorus compound before Hardener in the alkali-containing organ. nopolysiloxane is introduced.

The convertible organopolysiloxanes, which, depending on the degree of condensation, the alkaline condensing agent used, the starting organopolysiloxane (s), used to make the convertible organopolysiloxane, too highly viscous masses or elastic solids could be, are briefly referred to as "convertible organopolysiloxanes" or more precisely as "convertible ones." Methylpolysiloxanes «or» convertible methyl and phenylpolysiloxanesea. Organopolysiloxanes according to U.S. Patents 2,448,756, 2 448 556, 2 484 595, 2 457 688, 2 521 528, 2 451 137 and 2 490 357 are suitable.

Of course, according to the invention, in addition to those described above, caused by condensation of an organopolysiloxane or a mixture of organopolysiloxanes, which average about 1.95, preferably 1.98 to 2.1, organic groups each Containing silicon atom, too. other convertible organopolysiloxanes, the same or various bonded to the silicon by a carbon-silicon bond organ search containing substituents may be used. The convertible organopolysiloxanes include. generally polymeric diorganosiloxanes, up to 2 mole percent if desired copolymerized monoorganosiloxane, e.g. B. Monomethylsioxanreste may contain. To produce a convertible, for example heat convertible organopolysiloxane, it is preferred to use a compound of 1.99 to 2.01 as the starting organopolysiloxane organic groups, e.g. B. to use methyl groups per silicon atom in which more than 80% of the silicon atoms contain two alkyl groups bonded to the silicon.

In the case of the starting organopolysiloxanes used for polymerization with alkali the organic residues are essentially carbon-silicon bonds directly bonded to silicon, and the siloxane units essentially correspond to the general formula ReSiO (R = preferably methyl and / or phenyl radical). The polysiloxane can essentially the siloxane units contain (CH3) 2SiO or a copolymer of dimethylsiloxane with a minor amount (1 to 20 or more mole percent) of any of the following units individually or in combination: C6H5 (CH3) SiO and (C «; H5) 2SiO.

For the production of cured organopolysiloxanes with improved thermal stability and the other desirable ones mentioned. Properties. is advantageously 0.1 to 80 / o, but preferably 2 to 6o / & (based on the weight of the convertible Organopo. lysi. loxane) benzoyl peroxide, tert. Butyl perbenzoate, azonitriles, e.g. B. 2,2'-azobisisobutyrnitrile is used.

There will be products with improved elasticity, tensile strength and Tear resistance obtained. Furthermore, high-energy electrons can also be used for hardening be used.

In addition, the convertible organopolysiloxanes can contain fillers, z. B. titanium dioxide, silica airgel, lithopone, diatomaceous earth, by thermal Silica produced by decomposition, γ-aluminum oxide, calcium carbonate, polytetrafluoroethylene particles and fibers. The proportion of the added filler can be 0.05- up to about 3 or more times the proportion of the convertible organo polysiloxane. After mixing the filler and optionally the curing agent into the Organopolysiloxane is the convertible organopolysiloxane under pressure (about 14 to 70 kg / cm2 or more) heated to about 125 to 150 ° for about 5 minutes to 1/2 hour. In the case of molded parts, the curing of the organopolysiloxane is advantageous by heating performed to about 2500 or more within 12 to 36 hours.

The process by which. the organopolysiloxanes are stabilized by organic phosphorus compounds at elevated temperatures has not been fully elucidated. However, it is believed that conversions between. the organopolysiloxane, the alkali metal compound used as a polymerization agent and the organic phosphorus compound used in each case: The number of phenoxy groups that react with the potassium salt depends on the molar ratio of the organic phosphorus compound to the potassium silanolate. In some cases it can be desirable. to direct the reaction in such a way that mainly molar potassium diphenoxy-phosphate in other cases mainly dipotassium phenoxyphosphate is formed.

Several alkali phosphates are often formed.

The residue A formed according to the second equation is extreme heat resistant. The compound labeled B is also at elevated temperature stable and inert and does not appear to exert any adverse effects or become in Contact with the organopolysiloxane to decompose.

The invention is illustrated in the examples (data in parts by weight).

Example 1 About 1000 parts of octamethylcyclotetrasiloxane who in heated to 1500 in a known manner in a polymerization vessel. Then 0.1 Parts of potassium hydroxide and 13.3 parts of decamethylcyclotetrasiloxane were added and the Oily mixture kept at 1500 for about 4 hours to add the methylpolysiloxanes to a mixture of linear methylpoolysiloxanes with different molecular weights and a viscosity of about 2500 cP, the linear chains of which are formed by trimethylsiloxy groups have broken off to condense.

A sample of this oil is used to remove the lower-boiling volatile ones If the ingredients are heated to 3000 for 30 minutes, this is the "equilibrated" organopolysiloxane at this temperature already completely to products with low molecular weight depolymerized. However, in the hot Organopolysi loxane liquid immediately after their preparation, about 0.72 parts of triphenyl phosphate are intimately distributed, then can the "equilibrated" organopolysiloxane can be heated to 300 ° for 30 minutes to remove all to remove volatile components. There is a weight loss of about 19 ° / e, which consists largely of lower-boiling components. The viscosity of the oil is about 2500 after the volatile constituents are distilled off their removal about 4300 cP. The oil can be easily filtered and is at elevated levels Temperatures stable.

Example 2 400 parts of octamethylcydotetrasiloxane are in one with a stirrer provided reaction vessel heated to 150 °. Then 0.04 parts fine. divided potassium hydroxide and 1.32 parts of decamethyltetrasiloxane were added. The mixture is polymerized for 4 hours at 1500 to give a highly viscous product. When a sample of this well-known metbylpolysiloxane is placed in an oven for 30 minutes is heated to 300 °, a weight loss of about 90% occurs. In contrast in addition, the weight loss is when various amounts of triphenyl phosphate are added or tricresyl phosphate to the product heated to 150 if it is 30 minutes. in an oven heated to 300 °, only 16 to 18%.

When adding 5 parts of triphenyl phosphate (a little over 20 mol per mol KOH used) or from 0.5 part of triphenyl phosphate (a little over 2 moles per mole potassium hydroxide used) or 0.1 part tiphenyl phosphate (a little over 0.4 mol per mole of potassium hydroxide used) or 0.2 parts of tricresyl phosphate (about less than 1 mole per mole of potassium hydroxide used) or even as little as 0.05 part of triphenyl phosphate (a little more than 0.2 moles per mole of potassium hydroxide used) is the weight loss of volatiles after heating the samples to 3000 for 30 minutes from about 16 to 180 / s and is only slightly higher (about 19 to 20 percent by weight), when 0.05 parts of triphenyl phosphate are used.

In the protrude. the examples explain how a neutralization or removal of the alkaline "equilibrating" or polymerizing agent distilling off the lower-boiling volatile constituents from the condensed Polysiloxane can be avoided, so that these organopolysiloxane types are faster and can be processed more economically.

Example 3 400 parts of octamethylcyclotetrasiloxane are known in the art Way in a polymerization vessel with 0.04 parts of potassium hydroxide and 1.32 parts Decamethylcydotetrasiloxane mixed. The mixture is then left on for a long enough time about 1500 heated to a methylpolysiloxane with a viscosity of about 25,000 to get cP. 60 parts of octaphenylcyclotetrasiloxane are added and the Mixture heated to about 135 to 150 ° for about 4 hours to produce a methylphenylpolysiloxane with. higher To maintain viscosity. Will take a sample of this material for 30 minutes If heated to 300 °, a weight loss of about 99% occurs. But if only 0.1 Part of triphenyl phosphate is added to the highly viscous mass, the weight loss is if heated to 3000 for 30 minutes, only about 15 to 16%. Obviously effected the addition of the organophosphorus compound to a methylphenylpolysiloxane thereof Stabilization at elevated temperatures.

Example 4 This example illustrates the effect of organophosphorus compounds for the production of elastic polysiloxanes or silicone rubbers Organopolysioxanes. 400 parts of octamethylcyclotetrasiloxane are in one with one Reaction vessel heated to 150 °, then with 0.04 parts of potassium hydroxide and 0.132 parts of decamethylcyclotetrasiloxane are added and the mixture is heated for about 4 hours, until a highly viscous mass (hereinafter referred to as "immutable polydimethylsiloxane" marked), which hardly flows at room temperature. To rehearse this known convertible polydimethylsioxane different amounts of triphenyl phosphate, Trikresplphosphat or triphenylphosphit given. Then will. Proportions of each of these inactivated polymers on a rubber mixer with silica airgel and benzoyl peroxide mixed, to flatten at about 1500 20 minutes under a pressure of about 35 kg / cm2 Plates pressed and then 24 hours at 2500, a further 96 hours at 250 ° and heat aged 25 hours at 300 °. After that, each sample is checked for tensile strength and elongation investigated. Composition of the mass: convertible polydimethylsiloxane 400 parts of silica airgel ................ 180 benzoyl peroxide 6,6 "6,6 In der following. Table I is the amount of organophosphorus compound to be added in each case specified.

Table I. Share organic Phosphorus molar ratios Sample organic compound organic No. phosphorus- per 400 parts phosphorus- connection convertible connection Polydimethyl- per mole of 1 (0H siloxane 1 without no 0 control 2 triphenyl 0.1 part a little less phosphate as 1/2: 1 3 tricresyl 0.2 parts a little less phosphate as 1: 1 4 triphenyl 0.3 parts a little more phosphate as 1: 1 5 triphenyl 0.15 parts a little less phosphite as 1: 1 6 triphenyl 0.5 parts a little more phosphate as 2: 1 7 triphenyl 1.0 part a little less phosphite as 5: 1 Table II shows the physical properties of the various samples after heat aging.

Table II Sample no. 1 2 3 4 5 6 7 8 after 24 hours at 2500 Tensile strength, kg / cm2 ................ 42.2 45.7 48, 2 Elongation at break,% ................ 240 240 240 after 72 hours at 2500 Tensile strength, kg / cm2 ................ 38.7 Elongation at break,% ................ 150 after 96 hours at 2500 and 24 hours at 3000 Tensile strength, kg / cm2 ................ decomposed 48.2 50.1 fall *) Elongation at break,% ................ *) 130 145 after 96 hours at 2500 and 48 hours at 3000 Tensile strength, kg / cm2 ................ zer- 42.2 45.7 fall *) Elongation at break,% ................ *) 120 130 after 96 hours at 2500 and 72 hours at 3000 Tensile strength, kg / cm2 ................ decomposed 43.2 44.3 fall *) elongation at break,% ................ *) 100 90 tiach 1 hour at 1500 and 1 hour at 2500 and 96 hours at 3000 Tensile strength, kg / cm2 ................ dis- 38 fall *) Elongation at break% ................ *) 75 *) Plates completely crumbly.

Example 5 The example illustrates the beneficial effect of the organophosphorus verb indications in connection with alkaline condensed organopolysiloxanes for coatings, especially for glass fabrics. There are 400 parts of that described in Example 4 convertible methylpolysiloxane, the triphenyl phosphate in. those listed in Table III Contains amounts, with about 200 parts calcium carbonate and 18 parts benzoyperoxide mixed. Samples of this mixture are tightly closed with sufficient amounts of xylene homogeneous, practically stable dispersions with a solids content of about 34% mixed. Glass cloth is then made with these samples, the varying amounts of triphenyl phosphate included, coated and heated to 1250 for about 2 hours to remove the solvent remove. Thereafter, the mixture is heated to 3150 for a further 17 hours. The coated fabric is weighed to determine the amount of edition. The same thing will be done for control Glass fabric with the same materials as described above, but without the addition of Triphenyl phosphate, coated. In the following Table III are the amount of used Triphenyl phosphate and the amount of plaque remaining on each tissue sample given in%. The protective covering coated with the triphenyl phosphate Fabric is very flexible and therefore usable, while the covering without triphenylphosphate phat has disintegrated in powder form and can easily be blown off the surface, so that the pure glass fabric surface comes to light.

Table III Sample no. Control 819 # 10 Share organic Phosphorus binding on 400 parts poly dimethyl siloxane none # 0.1 0.5 5.0 Molar ratio organic Phosphorus bond per mole KOH .......... no something a little something less more more than than as 0.5: 1 2: 1 20: 1 Rest of the her- killed Belgaes in% .......... 0 37 *) 74 80 *) The amount of the covering remaining on the glass fabric can be increased to 80% if 1.3 parts of triphenyl phosphate are added to the covering mass after it has been produced and before it is applied to the fabric.

The convertible polysiloxanes behave as stated above very different in storage. When storing the convertible organopolysiloxanes under high humidity there is a decrease in the molecular weight and the Viscosity and the organopolysiloxane becomes "soupy". Becomes the convertible organopolysiloxane If stored for a long time in the absence of moisture, it becomes more viscous and somewhat "Annoying", is difficult to split up and modify on the mixing roller; rende Leave ingredients such as fillers and hardeners. difficult to get used to.

The stability of the convertible organopolysilox at e among different Storage conditions are determined by reading the penetrometer using a cylinder of 61/4 mm and a load of. 100 g determined.

The example below illustrates the effect of storing the convertible Organopolysiloxanes under different storage conditions and the effect of adding of tricresyl phosphate and triphenyl phosphate.

Example 6 A mixture of 100 parts of octamethylcyclotetraisloxane, 0.01 part KOH and 0.033 part decamethylcyclotetrasiloxane is used for about 4 hours heated to a temperature of 150. It becomes a highly viscous, convertible polydimylsioxane obtained, which flows only weakly at room temperature.

Samples of this heat convertible polydimethylsiloxane become 0.05 Weight percent tricresyl phosphate or triphenyl phosphate given. A control sample will be on an equal footing. without the addition of an organic phosphorus compound manufactured.

The viscosity of the control sample is higher than that of the samples with Additive. Samples of the polymers are kept for 43 days under various conditions, e.g. B. once at a relative humidity of 1000 / o and on the other hand at a relative humidity below 100%. stored. At the beginning and end of every attempt each of the samples is examined for viscosity and penetrometer value. In table IV the results of these investigations are given.

Table IV Sample No. Viscosity Penetrometer Value Test Conditions 9 9 000 000 1200 originally, high humidity 1 1 200 000 1200 originally, low humidity a 9 000 000 6200 after 43 days, high humidity 12 32 000 000 195 after 43 days, low humidity b 5 800 000 1755 originally, high humidity 5 600 000 1700 originally, low humidity 5 750 000 1685 after 43 days, high humidity b14 5 720 00 1610 after 43 days, low humidity 5 5 350 000 1750 originally, high humidity 5 5 460 000 1725 originally, low humidity 5 350 000 1700 after 43 days, high humidity c16 5 320 000 1645 after 43 days, low humidity a) control untreated, b) with added tricresyl triphosphate, c) with added triphenylphosphate.

The time of adding the organic phosphorus compound may be vary. The organic phosphorus compound can thus be added to the organopolysiloxane after it has reached the desired degree of polymerization, by another To prevent increase in viscosity, or the organic phosphorus compound can the treated organopolysiloxane with the fillers and the modifying ingredients be admitted. The organic phosphorus compound can. also the fillers, such as calcium carbonate (e.g. by treating it under suitable conditions), are added, which are then converted into the convertible organopolysiloxane on the usual Mixing rolls are incorporated.

Better results are obtained if the organic phosphorus compound admixed with the convertible organopolysiloxane before the filler or hardener will.

In addition to the fillers and hardeners mentioned, for example, other common ones can also be used. For the production of oil coating compounds The stabilized organopolysiloxanes become the convertible organopolysiloxane and / or the filler and / or optionally a hardening medium advantageous in liquid media, such as benzene, xylene, toluene, in a concentration of approx 5 to 50% of the solids content, based on the total weight of the coating mass, dissolved or dispersed. The twisting of dispersants and stabilizers can be beneficial. With the organopolysiloxanes stabilized according to the invention coated, heat-resistant fabrics, in particular glass fabrics, asbestos fabrics, polyethylene terephthalate fibers and fabrics, polyacrylonitrile fibers and fabrics are special for heating or others Types of lines suitable for elevated temperatures of around 250 to 3150 longer Withstand time when they were previously organopolysiloxane elastomers without organic phosphorus compounds could endure. Even after a long period of use at around 3150, larger amounts protect of the coating the heating cable, which even under extreme temperature conditions remains flexible.

The cured organopolysiloxane elastomers stabilized according to the invention withstand high temperatures (150 to 3150) for a long time and also keep theirs rubber-like properties at low temperatures, e.g. B. from - 1070. The hardened Organopolysiloxanes are suitable as insulation material for electrical Head for seals, shock absorbers and various other applications where the high heat resistance and flexibility at low temperatures of the invention stabilized organopolysiloxanes can be exploited.

For the polymerization of. Organopolysiloxanes or polymerization of Mixtures of organopolysiloxanes are also often acidic catalysts, such as z. B. sulfuric acid, hydrochloric acid, ferric chloride, used as a polymerization agent After the polymerization is complete, the acidic condensing agent is usually used neutralized with alkaline materials, especially alkali hydroxide. The arrears on alkali hydroxides or their salts (including silanolates) can be Usually not completely removed and have a disabling effect on the organopolysiloxanes. These difficulties can easily be solved by using small amounts of organic Fix phosphorus compounds according to the invention.

The permanent set is usually obtained by applying various Additives (e.g. certain quinones, mercury oxide) are reduced. By that through the additives according to the invention easily remove the low-boiling, volatile constituents from the stabilized. convertible organopolysiloxane. can be removed, the usual additives to reduce permanent deformation are more effective.

PATENT CLAIMS 1. Use of organic phosphorus compounds as a stabilizer against the action of heat for with the help of alkali compounds condensed organopolysiloxanes.

2. Use of esters, optionally by a hydrocarbon radical or acids of trivalent or pentavalent phosphorus substituted by a sulfur atom as a stabilizing agent according to claim 1.

Claims (1)

3. Use of organic phosphorus compounds for methyl, phenyl or methylphenylpolysiloxanes according to claim 1 or 2. 4. Use of triphenyl or tricresyl phosphate or triphenyl phosphite according to claims 1 and 3. References considered: U.S. Patent No. 2,553 643; German Patent No. 930 481; Hunyar, "Chemistry of Silicones", 1952, p.136 and 137.