BE466211A - - Google Patents

Description

       

   <Desc / Clms Page number 1>
 



  "Organosilicon Compositions and Methods for Preparing Them".



   The present invention relates to organosiloxanes and to processes for polymerizing them,
Organo-siloxanes are compositions comprising essentially silicon atoms linked to one another by oxygen atoms by the intermediary of chains, silicon-oxygen, therefore -Si-4-Si-, and having organic radicals attached to carbon-silicon chains with at least a few silicon atoms. They can be prepared by hydrolysis of a hydrolyzable organo-silane followed by condensation (partial or complete) of the hydrolysis product. They can also be prepared by hydrolysis and condensation of mixtures of different or-

 <Desc / Clms Page number 2>

 
 EMI2.1
 gano-si lanes h; ydrolyzable.

   In the latter case, hydrolyzable silanes, which do not contain organic radicals attached to silicon by carbon-silicon bonds, such as silicon tetrachloride or ethyl osthosilicate, can be included among organosilanes. , if desired. By employing such mixtures
 EMI2.2
 silanes, it is possible to prepare orsano-siloxanes which contain on average up to three organic radicals inclusive per silicon atom.
 EMI2.3
 



  Hydrolyzable orsano-silanes are derivatives of eo SIEd '- and have the general formula RySiX 4-y), in which R represents an organic radical attached to silicon by carbon-silicon bonds, X represents a ra - Easily hydrolyzable dical chosen from the class comprising halogens, amino, alkoxy, aroxy groups and one of the acyloxy radicals, and y is / integer ranging from 1 to 3. Among the organic radicals represented by the symbol R, there may be mentioned : aliphatic radicals such as
 EMI2.4
 methyl, ethyl, propyl, isopropyl, butyl, amyl, hexyl heptyl up to octodecyl and above, al-radicals
 EMI2.5
 cyclics such as cyclopentyl, cyclohexyl, / aryl radicals and alkG.1:

  yles such as plnyl, mono- and poly-alkylphenyls eo iai, ie the radicals tolyl, xylyl, mÓ8i tylc,,; 10110- di-, and tri-éthylphen3; les, mono-, di- and triproaylplenyl naphthyl, mono-, and poly-al: kylnaphthyls such as methylnaphthyl, diethylnaphthyl, tripropl, -, naphthnyls, tetrahydronaphthyl, anthracyl, arailcylos radicals such as benzyl, gJhenyls, alkyl radicals such as benzyl, gJhenyls, alkyl radicals such as alkyls methallyl, / allyl and heterocyclic radicals. The above organic radicals may also, if desired, contain substitute materials such as halogens.

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   Hydrolysis of the above silanes or mixtures thereof is usually accompanied by the condensation of hydroxy compounds usually forming to form siloxane bonds, hence -Si-01: '! Si. The formation of a siloxane bond generally occurs upon the close approximation of two hydroxyl groups and the subsequent removal of water.

   It can also occur upon close approximation of a hydrolyzable hydroxyl group such as halogen or acyloxyl or alkoxy followed and removal of halogen / hydrogen, acid or l The carboxylic alcohol respectively. The removals are catalyzed by mineral acids, particularly by hydrochloric and sulfuric acid and alkali metal hydroxides, particularly by sodium hydroxide. The product of hydrolysis and condensation consists of organo-siloxanes, which are partially or completely condensed and which have an average of up to three organic radicals inclusive attached to each silicon atom.

   Organo-siloxanes consist, as mentioned previously, in substance of silicon atoms joined by oxygen atoms by means of silicon-oxygen bonds and of organic radicals attached to silicon by means of carbon-silicon bonds, the possible residual valences of the silicon atoms being saturated with hydroxyl radicals and / or with non-hydrolyzed residual radicals such as halogens, alkoxy radicals mentioned above as hydrolyzable radicals.



   Organosiloxanes resulting from hydrolysis of organosilanes are generally, if not subjected to further processing, low molecular weight materials. Heating at high temperatures will cause continued condensation of the products

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 hydrolysis, which contain a significant amount of hydroxyl radicals, that is to say those which are partially condensed. As a result, either liquids of higher viscosity or solids are obtained.

   However, organosiloxanes which are substantially free from condensable hydroxyl radicals, i.e., those which are completely or substantially completely condensed, are heat resistant on their own. In general, organosilexanes having on average more than about 1.75 organic radicals per silicon atom, are particularly resistant to any continuation of the polymerization by heat, the said organosiloxanes having to be heated for several hours at high temperatures to show any noticeable change , although in many cases they do not undergo any change. Completely condensed organosiloxanes are valuable products when polymerized to form higher molecular weight compounds.

   Liquid materials, especially those which are fully condensed, are suitable for use as transmission or drive fluids, which require high-strength and high-stability liquids. Resinous solids, particularly those which have more than 1.6 organic radicals per silicon atom, enjoy great flexibility and strength. Various catalysts have been found capable of effectively accelerating polymerization in high molecular weight materials.

   However, in general, even with the aid of such polymerization catalysts, such as alkali and acid, the polymerization has required excessive time and extremely high temperature to reach the desired stage. particularly in the sensitive siloxane case

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 ment completely condensed. Accordingly, it would be desirable to be able to provide an agent which would aid in effecting the polymerization of organo-siloxanes at relatively low temperatures and which would substantially reduce the time required to effect the desired polymerization.



   The present invention consists in causing a reaction between organo-siloxanes, either partially or completely condensed, and a diacyl peroxide containing at least one aromatic acyl radical capable of entering into a reaction, and in re-operating the products of the reaction. .



   According to the invention, it has been observed that the organohiloxanes, the organic substitution elements of which consist essentially of hydrocarbon radicals attached to silicon by carbon-silicon bonds, and of which at least some are alkyl radicals, can be polymerized by treatment with acyl aromatic peroxides under conditions which promote the reaction between peroxides and siloxanes, and that the polymerization can be carried out at relatively low temperatures and in a relatively short time, which contrasts with the results produced by known polymerization agents. In addition, products having properties not heretofore obtained with the aid of other agents can be formed.



   The products of the polymerization can be liquids, gels, resinous solids, or rubbery compositions depending on the amount of peroxide employed, the time allowed for the progress of the reaction and the degree of organosubstitution. of the starting siloxane. General ep, liquid materials. Low viscosity materials can be converted, by the process according to the invention, to higher viscosity liquids in order to make them more suitable for particular applications in the field of transmission liquids.

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 sion and training.



   Liquid materials can also be polymerized to become solid and suitable as electrically insulating coatings for metallic conductors and as electrically insulating textile materials, such as fiberglass tape. . Low molecular weight organosiloxanes, containing on average between 1.75 and 2.25 organic radicals per silicon atom, can be converted, by treatment with aromatic acyl peroxides, into higher molecular weight liquids. .

   If the treatment can be continued for a sufficient time, they can be converted into gels, which provide compressible and elastic molding products of high heat stability, when treated with more peroxy.



   In general, the method forming the object of the invention can be practiced in the following manner. The organosiloxane to be treated is intimately mixed with a small amount of an aromatic acyl peroxide, preferably not more than 5% by weight of the siloxane at each stage of processing. The mixture is then heated to a temperature sufficiently above the decomposition temperature of the peroxide to produce a reaction between the peroxide and the regulable medium fairly quickly.

   It is preferable to employ the peroxide mixed with some inert filler, such as calcium dilate, in order to reduce the reactivity of the peroxide which in many cases reacts so violently that its use in the state. pure carries risks. It is also desirable not to employ too much peroxide at one time, since the production of the decomposition products of

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 peroxide is so rapid that it causes the formation of scum. This can be avoided by successive additions of extremely small amounts of peroxide. The degree of polymerization can be controlled by varying the amount of peroxide employed.

   Polymerization can also be terminated by lowering the reaction temperature to a point where the reaction ceases and removing the peroxide which has remained intact by suitable means, for example, by treatment with a reducing agent or passing through the peroxide. oxygen through the liquid.



   The reaction between the aromatic acyl peroxide and the organosiloxane is preferably carried out substantially in the absence of oxygen since the latter reduces, in a way not fully explained, the effectiveness of the peroxide. Where a large amount of liquid is processed, with the peroxide being submerged, the part below the surface reacts and its viscosity increases but the surface remains substantially unchanged. If a small amount of siloxaria is to be treated in a relatively shallow vessel, it is essential that oxygen be excluded for a complete reaction to occur. The exclusion of oxygen can be effected by carrying out the reaction under reduced pressure or by operating in an inert atmosphere, such as CO2, or by any other suitable method.



   If the starting organosiloxane is not liquid at the reaction temperature, but is solid, it can be processed in one or two ways. If it is soluble in a solvent boiling above the reaction temperature and if the solvent. is both inert and capable of dissolving the peroxide, this solvent can then be used as a reaction medium. Alternatively, the solid organosiloxane, either soluble or insoluble, can be finely ground with the

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 required amount of peroxide and then heated to reaction temperature.



   Among the aromatic acyl peroxides, which have been found to be effective in the application of the process making the object of this invention are the following: benzoyl peroxide, benzoylacetyl peroxide, dinaphthoyl peroxide, peroxide. of benzoyllauroyl.



  In general, any acyl peroxide which contains at least one eromatic / acyl radical is suitable. The acyl radical can contain inorganic substituents such as halogen, nitro groups.



   The mechanism of the reaction between the alkylsiloxanes and the acyl peroxide is not clearly explained. In the case of benzoyl peroxide, benzolic acid is a byproduct of the reaction. The reason why oxygen weakens the effectiveness of peroxide is also not known. Regardless of the particular mechanism, it is evident that the peroxide causes the siloxane molecules to join together to form molecules of higher molecular weight and greater viscosity.



   When it is desired to produce materials of high compressibility and high elasticity, while being of high heat resistance and having excellent electrical characteristics, the process according to the invention consists of treating organopolysiloxanes, whose organic substituents consist essentially of monovalent organic radicals attached to silicon by carbon-silicon bonds, each silicon atom having an average of 1.75 to 2.25 organic radicals and cepolysiloxane containing at least 40 mol percent of units of diorganosubstituted silicon oxide of formula RR'SiO, in which R and R 'are alkyl radicals,

   with a

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 diacyl peroxide, containing at least one aromatic acyl radical participating in the reaction, until a rubbery solid material is obtained.



   The preferred process for preparing the compressible and elastic products according to the invention generally comprises three stages. In the first stage, a low molecular weight organo-silosane, meeting the above conditions with regard to its composition and constitution and usually consisting of a low viscosity liquid, is polymerized so as to constitute a liquid. compision of a high molecular weight, non-fluid or only poorly fluid at room temperature. This composition can be an extremely viscous liquid, a gel, or even a solid.

   Polymerization to the high molecular weight stage can be carried out by any suitable method such as by the use of a dehydrating agent, if the siloxane is incompletely condensed or by treatment with a strong acid or with a strong alkali, if the siloxane contains fully condensed polymers. Another method which may be employed is that of forcing air through the siloxane at elevated temperatures until an extremely viscous liquid or gel is obtained.



   In another polymerization process, the siloxane is treated with an aromatic acyl peroxide at the reaction temperature to cause an increase in viscosity. The reaction temperature is near or above the decomposition temperature of the peroxide. If the treatment is continued long enough and the siloxane has the composition given above, a gel will form, which is suitable for use in the next stage of this process. It is better, but

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 not absolutely essential, that treatment with the pero-
 EMI10.1
 Oxide is carried out in the absence of oxygen, which appears to reduce the effectiveness of the peroxide particularly at the surface of the liquid siloxane treated.



   The second stage of the process according to the invention.
 EMI10.2
 consists in thoroughly mixing the high molecular weight composition obtained in the first stage with a low proportion of an aromatic acyl peroxide, preferably 2 to 6 percent by weight. The mixture, which
 EMI10.3
 The result is a surface which is susccpticlc to be worked and molded, which can be given any shape.



  If desired, a filler can be incorporated into the
 EMI10.4
 during the co-stage, in order to improve and improve the properties of the molding composition to meet the conditions required in applications and uses.
 EMI10.5
 specific sations.

   The third stage consists of introducing the molding composition obtained in the second stage into a mold from which oxygen is preferably excluded and then heating until a solid and rubbery product. sticky is obtained 'Oxygen has been found to reduce the effectiveness of the peroxide
 EMI10.6
 C0 \ 11, ';' 8 rolling agent and euapeach, in many cases forming a non-c.o.llarate surface to the molded product. ,, On ±:; Ónér :: \ l, it suffices to use a calib1 'mold:

  Cc b, air. However, in some applications it may not be necessary to employ a completely closed mold, for example when oxygen can be excluded by the use of a
 EMI10.7
 reduced pressure or an inert atmosphere co.Ll.IHe carbon dioxide. The temperature at which this stage of molding or "final treatment" takes place is again preferably close to the temperature of de-
 EMI10.8
 composition of the peroxide, that is to say greater than eu, 10Uo1,

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 for benzoyl peroxide. In general, a terminal processing temperature of between 125 and 200KC is employed.



   The process described above can be modified, if desired, in those cases where a filler is to be included in the molding composition. In such cases, it is not necessary to employ a material which itself exhibits the property of being little or no fluid, as indicated above. A more fluid siloxane may be employed when it is thoroughly mixed with a sufficient amount of filler and peroxide and gives a composition of such consistency as to be capable of being processed in a mold.

   When such a relatively low viscosity or low molecular weight liquid siloxane is employed, it is obviously necessary to add more peroxide in order to polymerize the liquid to the desired rubbery state. Liquid in a rubbery state can also be carried out in one step, by simply heating the resulting mixture to the reaction temperature. Another variant of the process in which a filler is employed involves incorporating the filler into the initial liquid siloxane of the first stage with only a sufficient amount of peroxide to transform the liquid into a gel. When the gel is obtained by heating, more peroxide is added as described in the second step.

   The result of the treatment is identical to that indicated for the process according to the aforementioned invention. The advantage of helping the feed during the first stage is better dispersion of the feed, resulting in a more homogeneous, bubble-free product.



   ,
Flexible, compressible, elastic and

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 EMI12.1
 of great stability there heat manufactured as a result of the present invention, can withstand temperatures up to 250 C. for more than one hundred hours and temperatures of the order of 350 C. for more twenty hours. Their tensile strength is relative
 EMI12.2
 If a heat-resistant inert filler like glass, alumina, titanium oxide, zinc oxide, etc., is incorporated into the mixture of peroxide and siloxane before molding.
 EMI12.3
 



  The o: 1. ';:; Ano-polysiloxanes (called coillbunOfllent "silicones"), are used to prepare the compressible and elastic products, are compositions comprising essentially silicon atoms linked to each other by oxygen atoms thundering 'chains
 EMI12.4
 silicon-oxygen of the -Si-O-Si- type, and having in llloyenl1c 1. 75 to 2.25 monovalent organic radicals linked by carbon-silicon bonds to each silicon atom. They must understand the unit of structure corresponding to the
 EMI12.5
 empirical formula HR'8iO where R and ia 'are alkyl radicals. It is desirable that the number of units of this formula present in the siloxanc be at least 40 percent of the total number of units of silicon contained in the siloxane.

   By unit of silicon, we mean any unit which corresponds to one of the formulas
 EMI12.6
 empirical results. Si02 'RSi03 / 21 F? 2Si0, and R3 sio 1/2 in which R is a monovalent organic radical connected
 EMI12.7
 to silic.imJ1 by carbon-silicon bonds. These o1 '. ::: anopolysiloxal1es can be prepared by hydrolysis of a hydrolyzed dtorC; 2-l1osilanc followed by the lJondol1u (tJarticL- le or complete) of the hydrolysis product. They can also be prepared by hydrolysis and mono condensation.
 EMI12.8
 of mixtures of different hydrolyzable orsano ilanes (; on-

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 holding at least 40 mol. percent of a hydrolysable dialkylsilane.

   In the latter case, hydrolyzable silanes which do not contain organic radicals attached to silicon by carbon-silicon bonds, such as silicon tetrachloride or ethyl orthosilicate, can be included in the organosilanes, If desired. By employing such mixtures of silanes in the appropriate proportions, it is possible to prepare organosiloxanes which contain on average between 1.75 and 2.25 organic radicals per silicon atom. - Provided that the siloxanes may contain several non-condensed hydroxyl groups as well as several residual non-hydrolyzable hydrolyzable radicals.



   For a better understanding of the invention, reference will be made to the following examples:
EXAMPLE 1
A dimethylsilicone with a viscosity of 8.500 centistokes is prepared by hydrolysis of dimethydiexysilane in the presence of 85% sulfuric acid as catalyst. This polymer is heated with various amounts of benzoyl peroxide to 125 ° C. for different times. The results obtained are collated in Table I.



   TABLE I
 EMI13.1
 
<tb>% <SEP> Peroxide <SEP> Viscosity <SEP> Treatment
<tb>
<tb>
<tb>
<tb>
<tb> Initial <SEP> Final <SEP>% <SEP> Increase <SEP> Time (Hrs) Time <SEP> 0 C
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> 0 <SEP> 8.500 <SEP> 9.750 <SEP> 15 <SEP> 2 <SEP> 125
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> 8.500 <SEP> 11.250 <SEP> 32 <SEP> 17 <SEP> 125
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> 0.1 <SEP> 8.500 <SEP> 11.538 <SEP> 39 <SEP> 2 <SEP> 125
<tb>
<tb>
<tb>
<tb>
<tb> 8. <SEP> 500 <SEP> 12.700 <SEP> 49.5 <SEP> 17 <SEP> 125
<tb>
<tb>
<tb>
<tb> 0.5 <SEP> 8.500 <SEP> 24.

   <SEP> 000 <SEP> "<SEP> 160 <SEP> 2 <SEP> 125
<tb>
<tb>
<tb> 8.500 <SEP> 38.000 <SEP> 347 <SEP> 17 <SEP> 125
<tb>
<tb>
<tb> 1.0 <SEP> 8.500 <SEP> freeze --- <SEP> 2 <SEP> 125
<tb>
 

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 EMI14.1
 Dicthßlsilicone was prepared By hydrolysis of diethyldichlorosilane The silica was then treated with hydroxide in an amount such as 1 ± flue; the raL-'Jol't: è., being the number of atobes do sailiciuui in the 8111I-u11 "; and the, 1: .. li ¯ of sodium hydroxide molecules is 100 JüUI '1.

   The final product is neutralized with 00,., And a liquid, with a viscosity of: 8.le to, 625 µ2mtistol # s, is removed. : ... 8 liç, uid <; is admittedly treated with benzoyl peroxide by sue-
 EMI14.2
 ceases by an amount of 2 L until a total of 6% is reached, each addition being made at the expiration of a Qh'uff2.te period of 17 hours to 125 ( The results obtained are r ('3su ,, a (,. S in Table II.



  TABLE II
 EMI14.3
 'Benzoyl peroxide Viscosity (centistokes)
 EMI14.4
 
<tb> Initial <SEP> End: ':. on
<tb>
<tb>
<tb> 0 <SEP> 625 <SEP> 712
<tb>
<tb>
<tb> 2 <SEP>% <SEP> 712 <SEP> 1690
<tb>
<tb>
<tb> 4 <SEP>% <SEP> 1690 <SEP> 3530
<tb>
<tb>
<tb> 6 <SEP>% <SEP> 3530 <SEP> freeze
<tb>
 It is found that when the starting liquid has the same viscosity, the benzoyl peroxide cannot be easily kept in suspension so that better results are obtained, if the liquid is repeatedly treated with the peroxide indicated in. the table above.
 EMI14.5
 ia; ::

  ? 1'I 3 A methylsiloxane uopolymer is prepared by hydrolysis of a mixture of 90 mol percent dimethyldiethoxy-

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 silane and 10 mole percent methyltriethoxysilane with aqueous hydrochloric acid solution and recovery of the oily product, obtained with a viscosity equal to 133 centistokes. This liquid is mixed with 2% by weight of benzoyl peroxide and heated to 125 ° C. for 17 hours. Its viscosity increases up to 300 centistokes. A further four percent of benzoyl peroxide is then added and the heating continued for 17 hours at 125 C. The product obtained is a gel. An untreated sample subjected to the same heating remains substantially unchanged.



     EXAMPLE 4.



   A methylsiloxane copolymer is prepared as follows; Hexamethyldisiloxane, dissolved in concentrated sulfuric acid, is added while stirring with dimethylsilicone of viscosity equal to 300 centistokes Gold continues to stir for a few minutes. Then an excess of water is added. The mixture is left to stand for one hour and then washed in a benzene solution to completely remove the aid. Benzene and lower polymers are removed by distillation to 230 ° C. The viscosity of the obtained product is 55 centistokes.

   This liquid is then subjected to repeated treatments with benzoyl peroxide, which gives the results shown in the following table.



   TABLE III
 EMI15.1
 
<tb> Peroxide <SEP> of <SEP> Viscosity <SEP> (.Centistokes) <SEP> Treatment
<tb>
 
 EMI15.2
 benzoyl ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ Initial 'Finale Tems (Frs.) Teinp. vs.



  0 y, 55 55 47 125, 3% 55 72 17 125 4% 72 ---- l2 17 125 6 â 132 gel 17 125 j fl /

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 EMI16.1
 NXEL.PLE 5 The uyclic tdtra! Nere of IW enyl-oati.y-1¯sil .: i: c. The t4tr.unthyltétr.henylcyclotétrasiZo> .r¯e-is txaitated. ; ec: various amounts of be.zzo; psroxide, Jle. Leo rce-uitabs are grouped together in the following table following csux obtained by heating a quantity of the silicone sa: .e peroxide at 1850C.



  IVF TABLE
 EMI16.2
 9etoçgj Time s @ Viscosity (L; fmt: Ls¯to: #s) Initial. Final li Increase 0 18 146 153 ---- 0 17 153 144 ---- 0 18 144 155 ---- 5.6 is 146 lslo 112
 EMI16.3
 
<tb> 8.8 <SEP> 17 <SEP> 310 <SEP> 750 <SEP> 142
<tb>
 
 EMI16.4
 9.3 17 750 S2.50 300
 EMI16.5
 It is found that in general, siloxans which contain aryl radicals as well as alkyls require more peroxide than alkylsiloxans. The cause of this is not currently known. However a cel cs.outchout3u.x p8Ut Strs finally obtained if we add 8ui'l: i'I: .aadn't de '.: T? U Xjî C '.1? L3ààijlé 6 Cyclic reading of n .., rlvl,; th "ls'll'" (); 1 "(tv ':.; T' .-; a tr: ¯-? ¯ : E., 'C1L.; T; 10'rJ.àlZ.O.: 1G -'? 2ût treated 2.V8l: various quuutits of éJ <9toxj, ai; the bensoyie J 125 U.

   The results obtained are r ^: ¯, e..W 1 in the following table following those obtained with non-treated samples QU bcenzoyie peroxide.

 <Desc / Clms Page number 17>

 



  TABLE V.
 EMI17.1
 Peroxide% Time (Hrs.) ViS90sity (centistokes)
 EMI17.2
 
<tb> Initial <SEP> Final <SEP>% <SEP> Increase
<tb>
<tb> 0 <SEP> 18 <SEP> 59.2 <SEP> 65 <SEP> ---
<tb>
<tb> 0 <SEP> 17 <SEP> 65 <SEP> 61
<tb>
<tb> 0 <SEP> 18 <SEP> 61 <SEP> 47.5 <SEP> ---
<tb>
<tb> 6.1 <SEP> 18 <SEP> 59.2 <SEP> 110.0 <SEP> 85
<tb>
<tb> 8.1 <SEP> 17 <SEP> 110 <SEP> 251 <SEP> 128
<tb>
<tb> 8.1 <SEP> 18 <SEP> 251 <SEP> 625 <SEP> 148
<tb>
 EXAMPLE y.

   
 EMI17.3
 Octadecamethylocttisiloxane C) H3 W 33 3 @ CH3-Si- 0-Si- 0-Si-cE is prepared by hydrolyzing equal amounts.
 EMI17.4
 3 'ô t bzz3 3 0113 OH3 t UH3 leculars of dimethyldiethoxysilane and trilaethylethoxysilane and by fractionating the products of the hydro-
 EMI17.5
 lysis for r.êaú 're1:

  'the aforementioned siloxanes' boiling at 102 ° C. under 5 mm. Samples of this material are treated with various amounts of benzoyl peroxide at 125 C. The results are collated in the following table following those obtained with samples not treated with peroxide, TABLE VI
 EMI17.6
 Peroxide% Time (Hrs.) Viscosity- (Centistokes)
 EMI17.7
 
<tb> Initial <SEP> Final <SEP>% <SEP> Increase
<tb>
<tb>
<tb>
<tb> 0 <SEP> 18 <SEP> 3.6 <SEP> 3.6 <SEP> ---
<tb>
<tb>
<tb>
<tb>
<tb> 17 <SEP> 3.6 <SEP> 3.6
<tb>
<tb>
<tb>
<tb>
<tb> 0 <SEP> 18 <SEP> 3.6 <SEP> 3.6
<tb>
<tb>
<tb>
<tb>
<tb> 5.9 <SEP> 18 <SEP> 3.6 <SEP> 4. <SEP> 0 <SEP> 11
<tb>
<tb>
<tb>
<tb>
<tb> 9.0 <SEP> 17 <SEP> 4.0 <SEP> 5.4 <SEP> 35
<tb>
<tb>
<tb>
<tb>
<tb> 8.7 <SEP> 18 <SEP> 5.

   <SEP> 4 <SEP> .. <SEP> 6.6 <SEP> 22
<tb>
 

 <Desc / Clms Page number 18>

   The relatively small increase in viscosity obtained
 EMI18.1
 in the case of the aforementioned silos ,, 7-anus is due 8, the key f ai ";" t cA- deur of the starting L1U..C, 's.L11C3:, i'. To obtain a high c; v.,;.; Ei: - tttion of the viscosity, large quantities of peroxide are necessary,
EXAMPLE 8
Liquid phenylmethylsiloxane is prepared in the following manner: 1.05 months of dephhyl bromide and 1.05 months of methyl chloride react simultaneously with
 EMI18.2
 magnesiuci.

   The product of the Grijnard reaction, which results from it, is then combined 8, silicon tetrachloride,
 EMI18.3
 so as to obtain a degree of substitution of 2; 1. The product is hydrolyzed by adding a large excess of water. We
 EMI18.4
 recovers an oil, which is heated to 275 C. under 15 mtu. and 8% volatile tuaters are removed by distillation, leaving a liquid with a viscosity of 2.10 centistokes. The liquid is treated with benzoyl peroxide at 125 ° C. The results obtained are collated in the following table after those obtained with a sample not treated with peroxide.



   TABLE VII
 EMI18.5
 Peox, de ô Tetnps Hrs Viscosity ((; ntisto1cest Initial Final% Ausoientation
 EMI18.6
 
<tb> 0 <SEP> 18 <SEP> 2100 <SEP> 4200 <SEP> 100
<tb>
<tb> 1.53 <SEP> 18 <SEP> 2100 <SEP> 5450 <SEP> 160
<tb>
 
 EMI18.7
 EXE;, IPI3 9 Liquid phenylethylsiloxano (prepared in a manner analogous to that described in Example 8) is treated with benzoyl peroxide at 125 C.

   The results obtained are
 EMI18.8
 gathered in the following tablejj¯¯ after those obtained

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 with a sample not treated with peroxide.
 EMI19.1
 TAJ31JEAU viii
 EMI19.2
 Peroxide ¯ Tc-a s îirsy Visuosite (Lentistokas)
 EMI19.3
 
<tb> Initial <SEP> Final <SEP>% <SEP> Increase
<tb>
<tb> 0 <SEP> 18 <SEP> 1180 <SEP> 13.500 <SEP> 1040
<tb>
<tb>
<tb> 6.1 <SEP> 18 <SEP> 1180 <SEP> 21.000 <SEP> 1680
<tb>
 
In this example and in the previous example, it can be seen that a significant increase in viscosity is obtained by heating alone, thanks to the presence of
 EMI19.4
 hydroxyl groupspt to the oxidation of alkyl radicals.



  It can also be seen that the use of benzoyl peroxide produces a more substantial increase in viscosity.
 EMI19.5
 



  E] 1EMpIDJ 10.



   A 50 month per cent mixture of ethyl silicate and ethoxysilane is introduced dropwise into a 50% solution of 1N sulfuric acid and in alcohol and refluxed for three hours. Another 20 month percent trimethylethoxysilane is then added and heating under reflux is continued for two hours. The reaction product is washed with water and an oil remains, from which the lower polymers are distilled off at 230 ° C. in a CO 2 atmosphere. The material obtained is a resin
 EMI19.6
 sticky, therinosplastic, the melting point of which increases if it is mixed with various amounts of benzoyl peroxide while heating to 150 C. The results are collated in the following table.

 <Desc / Clms Page number 20>

 



    TABLE IX
 EMI20.1
 Peroxide (ïf) Time {1i1rs..l Temp. C. Melting point afée - a8Q.



  0 0 --- less than 25? U
 EMI20.2
 
<tb> c <SEP> 17 <SEP> 150 <SEP> 40-70 C.
<tb>
<tb> 2 <SEP> 17 <SEP> 150 <SEP> 58-85 C.
<tb>
 
 EMI20.3
 



  5 17 150 62-l0go '..,.



  10 17 150 80-13S \ "EXAMPLE 11
 EMI20.4
 : L1 a. It has already been mentioned that the treatment of alkylsiloxanes with aromatic acyl peroxides is preferably carried out above the temperature of decomposition of the peroxide by heat. The literature points out
 EMI20.5
 that the decomposition temperature of bal peroxide, '¯ -71 is l10 c. The following table shows the effect of temperature and the amount of benzoyl peroxide on the increase in viscosity of a dinethyllyisilo: <# ne of 450 centistokes.
 EMI20.6
 TA..t.: J..8..W X.
 EMI20.7
 Pe o ;; ycze Time. fieanps. ; u; cnemt, i, io 0 je la vi; c; oslt 0.36 1000C 40 min.



  U. 39 100 c 40 min. 8.6 15 1 125. 40 min. ;.: .. 4 0.86 1250G 40 min. z 0.39 150 d 40 min. 53.7
 EMI20.8
 
<tb> 0.62 <SEP> 150 C <SEP> 40 <SEP> min. <SEP> 47.0
<tb>
 
 EMI20.9
 0.93 150 C 40 rain. 47,
 EMI20.10
 
<tb> 0.93 <SEP> 150 C, <SEP> 960 <SEP> min. <SEP> 100. <SEP> 0
<tb>
 
 EMI20.11
 It appears from the above table that, at 1 * 100OL, some decomposition of the peroxide takes place. However, the degree of decomposition increases between 100 and 150 C. to such an extent that the increase in the viscosity of the siloxane for a given time is relatively independent.

 <Desc / Clms Page number 21>

 the amount of peroxide used, as long as there is sufficient peroxide to continue the reaction,
EXAMPLE 12.



   Liquid dimethylsilicone with a viscosity of 1000 centistokes is prepared by refluxing a mixture of two volumes of dimethyldiethoxysilane, one volume of 95% ethyl alcohol and one volume of hydrochloric acid for four hours, washing the product, drying the oily liquid formed, and then distilling up to 2500C. under 0.5 mm. to remove lower polymers.



  The undistilled portion of the liquid is then thoroughly mixed with about 3% by weight of benzoyll peroxide in the form of "Luperco A", which comprises about 23% by weight of benzoyl peroxide precipitated on calcium sulfate. The resulting mixture is heated at 150 ° C. for two hours, after which a gel has formed which is very elastic, sticky and insoluble in benzene.



  This gel is then ground with about 25% by weight of alkali-free asbestos and three parts by weight of benzoyl peroxide. The product has the consistency of a paste. It is then poured into a mold protected from oxygen. The mold and its contents are heated to 150 oU. for about half an hour. At the end of this time, the contents of the mold have taken and form a solid, rubbery, cohesive, non-sticky body. Similar products are obtained with other fillers than asbestos, such as clay, airgel, flaked fiberglass, iron oxide, bentonite, alumina, zinc oxide, magnesia, lead oxide, titanium oxide and other charges.

   These products, in general, exhibit unexpectedly rubbery characteristics, and present /

 <Desc / Clms Page number 22>

 also high heat resistance.



   In general, it has been found that the treatment of organosiloxanes having on average less than 1.75 organic radicals per silicon atom, such as methyl- or ethyl-silicic acid produced according to the invention with a peroxide of 'aromatic acyl, first a more viscous liquid, and when further processing, a resinous solid. When the degree of organosubstitution is between 1.75 and 2.25, the peroxide treatment first produces more viscous liquids and, with further processing, salts and finally rubbery solids resistant to water. heat and having excellent electrical characteristics.

   The treatment of organosiloxanes, the degree of substitution of which exceeds 2.25, gives products usually consisting of liquids or thermoplastic solids.



     EXAMPLE 13
In this example, the organosiloxane is polymerized until a high molecular weight gel is formed using benzoyl peroxide. However, as far as this part of the process is concerned, other polymerization agents could have been employed, as mentioned above.



   Liquid dimethylsilicone having a viscosity of 1000 centistokes is prepared by refluxing a mixture of two volumes of dimethyldiethoxysilane, one volume of 95% ethyl alcohol and one volume of aqueous hydrochloric acid for four hours, washing the product, drying the oily liquid formed and then distilling up to 250 ° C. under 0.5 mm. to remove lower polymers. The undistilled portion of the liquid is then thoroughly mixed at about 3% by weight.

 <Desc / Clms Page number 23>

 of benzoyll peroxide in the form of "Luperco A", which contains about 23% of benzoyl peroxide precipitated on calcium sulfate. It is preferred to use the peroxide mixed with calcium sulfate, because it reacts more powerfully than pure peroxide.

   The calcium sulfate in no way interferes with the manufacture of the materials according to the invention. The resulting mixture is heated at 150 ° C. for two hours, after which a gel has formed which is very elastic, sticky and insoluble in benzene. This gel is then ground with approximately 25 parts by weight of alkali-free asbestos per 100 parts of gel and 3 parts by weight of benzoyl peroxide. The product has the consistency of a paste. It is then poured into a mold protected from oxygen. The mold and its contents are heated in an oven for about half an hour at 15,000. After this heating, the contents of the mold have set and form a rubbery, cohesive, non-sticky solid.



   In the above process, the amount of benzoyl peroxide added to the liquid dimethylsilicone at the start can vary. In general, the greater the amount of peroxide employed, the firmer the gel obtained will be and the harder the final molded product will be.



   If the amount of benzoyl peroxide used at the start is less than 1%, a gel is obtained which is very sticky. When this extremely sticky gel is mixed with 4-6 benzoyl peroxide and a load and then heated to 150 ° C. for about half an hour in a mold, a permanently foamy, high strength rubbery material is obtained. , in the heat. It is necessary to leave a free space in the mold to allow the expansion of the siloxane, while it is preferable to exclude the oxygen at the same time so that the

 <Desc / Clms Page number 24>

 setting takes place quickly and completely.

   The mold should also be allowed time to cool before removing the molded product in order to give any gases which might be trapped in the cells of the rubber siloxane an opportunity to escape. This cellular molded product is compressible, elastic and retains its properties even if maintained at a temperature above 200 ° C. for several hours.



    For example, a sample with 33% iron oxide, kept at 250 C. for 22 hours, loses only 9.5% of its weight, its dimensions vary only / 3.3% and its compressibility or hardness. only decreases by 4%.



   The same cellular product or frothy ant rubbery material can also be obtained, in part of a frankly fluid polysiloxane, by mixing it with peroxide and filler and then proceeding as described above. The prerequisites for the formation of such a foamy rubbery material are the rapid reaction of a mixture of peroxide and either a liquid siloxane or a very sticky gel in a medium from which oxygen is excluded and which has sufficient volume to permit rapid expansion of the reaction product.



   The time required to convert the initial liquid dimethylsilicone to a gel depends on the amount of peroxide employed, the viscosity of the starting silicone, which is preferably 1000 centistokes or more, and the temperature which is, preferably greater than 100 ° C. In some cases, 17 hours are required to reach a gel stage.



     EXAMPLE 14
Liquid diethylsilicone is prepared at low

 <Desc / Clms Page number 25>

 viscosity when hydrolyzing diethylisilicum dichloride.



  The diethylsilicone with 2% benzoylacetyl peroxide is thoroughly mixed and then heated at 150 ° C. for 17 hours. The resulting product is a sticky gel. The latter is ground with an equal weight of glass fiber flakes (3 mm.) And an additional 6% by weight of peroxide. The mixture is then heated in a mold away from air at 150 C. for one hour, The molded product resembles that obtained according to Example 1 and has an extensibility of 125% and a hardness of 42 measured with a durometer. Shore.



     EXAMPLE 15
To 2000 centistoke fluid dimethylsilicone was added 6% by weight of "Luperoo. A" fluid. The dimethylsilicone is placed in a Baker-Perkins wrap mixer and the powdered "Luperco A" is added through a 100 mesh sieve with the mixer running and the addition of "Luperco A" taking place at room temperature. ambient. The lid is placed on the mixer and the mixer is vacuumed to approximately 0.5 inch of pressure. Steam at four kilograms per square centimeter is then introduced into the envelope. The contents are mixed for 30 minutes and then cooled. At this stage, the product is a soft, oily, rubbery, and transparent gel in thin layers.



   Per 100 parts of gel contained in the mixer, 62 parts of finely divided calcium carbonate and a further 20 parts of "Luperco A" are then added. Stirring continues at room temperature for thirty minutes. The resulting mixture is then removed and worked in a two-roll rubber mixer at room temperature to achieve homogeneity. At this stage, ,

 <Desc / Clms Page number 26>

 the product is a white-gray foam rubber which does not adhere to itself and is very soft.



   The foam rubber material is then used to make flat sheets or rubber like sheets for insulating cables as follows; A) Molding of flat sheets.



   The "crepe" or foam rubber is poured into a cold mold of a pressure molding press and maintained under 35 kgs / cm2 and a vapor pressure of 10 kgs./cm2 on the plates (165 C. in the mold ) during one hour . The press is cooled to temperature before removing the pressure. The molded part is heated in an air oven at 100 ° C. for 16 hours to improve toughness. A dumbbell-shaped test piece having 6 mm. in width and 5 mm. of thickness at the narrow section has an extension strength of 5.5 Kgs./cm2, an elongation of 160% and shows after the test an elasticity of 98% of that of the beginning.



   B) Molding of insulation for wires.



   One end of a copper wire conductor from a motor is roughly wrapped with "crepe" and the wire is stretched and held under tension in a centering device in a removable mold. The mold is assembled and placed in an air oven at 175 ° C. for one hour. The mold is then removed from the oven and allowed to cool. There is thus obtained an insulated wire covered with a rubbery-white material, elastic, and uniformly distributed. The hardness is 28 on the "A" scale of the Shore durometer.

   After drying for 16 hours at 100 c .; , its toughness and hardness increase considerably and it resists for 40 hours at 250 C. without appreciable change in dimensions, not accusing

 <Desc / Clms Page number 27>

 a weight loss of 5%. The hardness on the "Shore A" scale rises to 39. After total exposure for 48 hours at 250 ° C. the sample is found to have the following electrical properties;
1000 periods 1.000.OOO Periods dielectric constant 3.83 3.65 'power factor 0.12% 0.48% Siloxane rubber adheres intimately to the copper conductor and is exceptionally resistant to stripping, oil, water and gasoline.



   Similar fillers, other than calcium carbonate, are used by generally following the same process. The results are collated in Table XI.



  Under item 1, scn, t given them. percentages of "Luperco A" used to polymerize the fluid dimethylsiliuone of 2000 cs. in a gel. Under item 2 are given the parts of filler added to the gel and under item 3 are given the additional parts of "Luperco A" mixed with the gel. The other remaining items are explained by themselves.



   TABLE XI
 EMI27.1
 
<tb> Asbestos <SEP> washed <SEP> Oxide <SEP> Flakes <SEP> of <SEP> fi-
<tb>
<tb> without <SEP> acid <SEP> from <SEP> iron <SEP> bricks <SEP> from <SEP> glass
<tb>
<tb>
<tb> (1/8 ")
<tb>
<tb>
<tb>
<tb>
<tb> 1.% <SEP> Luperco <SEP> A <SEP> 8.7 <SEP> 8.7 <SEP> 3.9
<tb>
<tb>
<tb>
<tb>
<tb> 2. <SEP> Parts <SEP> of <SEP> loads <SEP> by <SEP> 100 <SEP> parts <SEP> 60 <SEP> 150 <SEP> 150
<tb>
<tb>
<tb> from <SEP> freeze.
<tb>
<tb>
<tb>
<tb>
<tb>



  3. <SEP> Parts <SEP> of <SEP> Luperco <SEP> A <SEP> by <SEP> 100 <SEP> by-
<tb>
<tb>
<tb> ties <SEP> of <SEP> gel <SEP> 20 <SEP> 20 <SEP> 20
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> 4. <SEP> Conditions <SEP> of the <SEP> molding
<tb>
<tb>
<tb>
<tb>
<tb> Time <SEP> 1 <SEP> hr. <SEP> 1 <SEP> hr. <SEP> 1 <SEP> hr. <SEP>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>



  Temp. <SEP> C <SEP> 175 <SEP> 175 <SEP> 175
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> Pressure <SEP> (pounds / inch <SEP> square) <SEP> 1000 <SEP> 1000 <SEP> 1000
<tb>
 

 <Desc / Clms Page number 28>

 
 EMI28.1
 
<tb> 5. <SEP> Stability <SEP> at <SEP> the <SEP> heat
<tb>
 
 EMI28.2
 DuroMè'Ere Shore
 EMI28.3
 
<tb> molded <SEP> 49 <SEP> 42 <SEP> 62
<tb>
 
 EMI28.4
 24 h., Ures 250 (; 62 77 87
 EMI28.5
 
<tb> 48 <SEP> hours <SEP> to <SEP> 250 C <SEP> 68 <SEP> 84 <SEP> 94
<tb>
<tb> 6. <SEP> Stability <SEP> at <SEP> the <SEP> heat
<tb>% <SEP> Loss <SEP> of <SEP> weight
<tb>
 
 EMI28.6
 24 hours z, 2500 6 6 '' r 48 hours at 250 C 7 6 12 7.

   Resiatance taotion in Kgs / cI112 G. 3, 3 12
 EMI28.7
 
<tb> 8. <SEP> Elongation, <SEP>% ...... <SEP> 50 <SEP> 75 <SEP> 55
<tb>
<tb> 9. <SEP> Elasticity <SEP> recovered <SEP>% <SEP> 99 <SEP> 98 <SEP> 98
<tb>
   EXAMPLE 16 Per 100 parts of 7600 centipoi- dimethylsilicone
 EMI28.8
 In the fluid state, 21.8 parts of "Luperco A" and 60 parts of ly2a? ico Brown (iron oxide) are added. The élance is well mixed at room temperature by passing it four times through a rubber mixer with three cylinders. A very soft, sticky, red-brown product by product "A" is obtained. five disks each having 7.5 om. of diameter are cut out of a hot-cleaned fiberglass cloth.

   The sticky product - then applies
 EMI28.9
 on said discs using a hand roller. These impregnated discs are laid with layers of rubbery, greyish-white "crepe" designated "B", prepared as in the preceding example using calcium carbonate as the filler. lamellar product contains approximately 10 parts by weight of "A", 7 parts by weight of tissue from
 EMI28.10
 glass fiber and 78 parts of 11 ± ". The lamellar rmg is then placed in a die-casting press.
 EMI28.11
 70 k; e, per cm 2 at 170 C. for one hour.

   The lamellar product is an excellent material for joints, The examples above illustrate the different

 <Desc / Clms Page number 29>

 methods by which the novel molding compositions and molded products can be made. Analogous compositions and blind and free of charge products are produced with organosiloxanes other than those used in the preceding examples. Among these other siloxanes, mention may be made of a chlorinated dimethylsilicone containing 9.75% of chlorine which, by treatment according to the process, may be mentioned. described in Example 1 gives a rubbery, non-sticky product with an extensibility of 140% and an Si-when hardness of 41.

   The same process was used to make a rubbery product starting from a methylsiloxane containing 45 parts of monomethylsilicon units. The product has a Shore hardness of 50. Similar rubbery products are obtained by mixing liquid dimethylsilicones having liquid. viscosities of 10 4 and 10 6 centistokes, respectively, with fillers and benzoylacetyl peroxide and then heating at 150 ° C. for 60 minutes.



  A copolymeric organo-siloxane mainly containing dimethylsilicon radicals, the remainder being essentially phenylethylsilicon gives a rubbery, elastic p.ro, product of great heat stability when subjected to treatment. according to the process of Example 1.



   In the examples above, the molding compositions are made with siloxanes in the form of gels. Although gels are more suitable for processing for most applications, it is not absolutely essential that siloxanes be in this form. As highlighted above, they can be liquid or even solid. If they are liquid, it is only necessary that they have a sufficient viscosity to lend themselves to molding operations. and if char-

 <Desc / Clms Page number 30>

 When these are used, the liquids can be completely fluid, since the filler, if it is present in sufficient quantity, can form a pasty mass with the liquid.

   If the siloxanes are solid, they can be pulverized and mixed with the peroxide and, if desired, a filler. The resulting powder is then suitable for use as a molding composition as described above.



     The use of a filler in the molding compositions according to the invention is desirable in many instances in order to improve and modify the properties of the final molded product. Among the fillers employed are the following, asbestos, 188 clay, "silene" (hydrated calcium silicate), defined sulfide, silicaaerogel, buca clay, barium titanite, fiberglass flakes, iron oxide, bentonite. Wyoming. lithopone, zinc oxide, titanium oxide, magnesia, pulverized graphite, pulverized slate, pulverized mica, celite, T-calcine, Pbo2 'PbO, blue lead, dehydrated alumina and hydrated alumina.



  In general, it is preferred to employ inorganic materials, heat resistant and melting above 350 ° C., such as silicates, polyvalent metal oxides, etc. The particular filler to be chosen depends on the specific property or properties that it is desired to obtain. If high strength, toughness, or extensibility is desired, zinc oxide, titanium oxide, and aluminum oxide hydrate are best.

   If low weight loss, and small dimensional changes after long term exposure of the molded product to high temperatures is desired, asbestos is an excellent filler. If an elastic and cellular product is desired, non-fibrous fillers such as hydrated alumina and iron oxide combined with an aromatic acyl peroxide and an organosiloxane of the specified composition.

 <Desc / Clms Page number 31>

   rement will produce rubbery, foamy products with high heat resistance. If the oon desires the product to solidify quickly, iron oxide is the best filler.



   The following table shows the effect of various fillers on the Heat Stability of the dimethylsiloxane products according to the invention. Samples of the molded product are successively heated to three temperatures: 250 C for 22 hours, 300 C for 25 hours and 350 C for 20 hours Weight losses and shrinkage changes are calculated as a percent difference with the corresponding property at departure .



   TABLE XII
 EMI31.1
 
<tb> Total <SEP> change <SEP> to <SEP>% <SEP> of the <SEP> properties
<tb>
<tb> Load <SEP> weight <SEP> weight <SEP> ¯¯¯¯¯¯dimensions¯¯¯¯
<tb>
<tb> 2500 <SEP> 3000 <SEP> 3500 <SEP> 2500 <SEP> 3000 <SEP> 3500
<tb>
<tb>
<tb>
<tb>
<tb> Silène <SEP> 30 <SEP> 6.5 <SEP> 41. <SEP> 0 <SEP> 58.6 <SEP> 3. <SEP> 0 <SEP> 11. <SEP> 5 <SEP> 12.0
<tb>
<tb> Aeregel <SEP> 20 <SEP> 17.5 <SEP> 47.0 <SEP> 62.1 <SEP> 5.5 <SEP> 11. <SEP> 0 <SEP> 11.8
<tb>
<tb> clay <SEP> 188 <SEP> 50 <SEP> 26.0 <SEP> 44.0 <SEP> 45.4 <SEP> 6.3 <SEP> 7.5 <SEP> 9.5
<tb>
<tb> clay <SEP> .Buca <SEP> 50 <SEP> 13.0 <SEP> 28.5 <SEP> 40.4 <SEP> 6. <SEP> 0 <SEP> 6. <SEP> 0 <SEP> 9.05
<tb>
<tb> Asbestos <SEP> 33 <SEP> 4. <SEP> 5 <SEP> 10. <SEP> 0 <SEP> 29.2 <SEP> 1. <SEP> 5 <SEP> 1. <SEP> 5 <SEP > 6.1
<tb>
<tb> Oxide <SEP> of <SEP> iron <SEP> 33 <SEP> 9.5 <SEP> 44.5 <SEP> 63.8 <SEP> 3.

   <SEP> 3 <SEP> 23. <SEP> 0 <SEP> 30.2
<tb>
 
The amount of filler, which can be tolerated in the molded products also depends on the specific properties desired. The amount also varies from material to material, since each filler has its particular properties. In general, at least 100 parts of filler can be used per 100 parts of siloxane. In the case of iron oxide, hydrated alumina, zinc oxide, and titanium oxide, larger amounts may even be

 <Desc / Clms Page number 32>

 employees. He has. it has been found that up to 150 parts by weight of iron oxide can be used with 100 parts of siloxane.

   The silene causes the mixture to over-dry, so that 25% by weight is approximately the maximum, which should be used per 100 parts of siloxane. Asbestos, preferably stripped of acid by washing, is one of the best fillers because of the high heat resistance of the rubber products in which it is incorporated. Up to a total of 75 parts by weight of asbestos per 100 parts by weight of siloxane is incorporated into the product.



  Fiberglass is another payload, especially in the form of flakes. Amounts up to 50 parts by weight can be mixed with 100 parts by weight of siloxane.



   In the following table are given some physical properties of different molded products containing various fillers. The products are all prepared in substantially the same way. A liquid dimethylsilicone with a viscosity of 2100 centistokes is treated with 2 wt% benzoyl peroxide, such as "Luperco A" at 125-150 ° C. for 17 hours to form a gel. this gel is ground with an equal amount of filler and an additional 6% benzoyl peroxide such as "Luperce A". The column labeled "150 C treatment" indicates the minutes during which the molding composition is kept in the mold. 150 C.

 <Desc / Clms Page number 33>

 



  TABLE XIII
 EMI33.1
 
<tb> Load <SEP> '<SEP> treatment <SEP> Extension <SEP> hardness <SEP> factor <SEP> of
<tb>
<tb> 150 C <SEP> Shore <SEP> power <SEP> 106
<tb>
<tb> periods
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> Fe2O3 <SEP> 30 <SEP> 140 <SEP> 26 <SEP> 0.768
<tb>
<tb>
<tb>
<tb> Flakes <SEP> from <SEP> fi-
<tb>
<tb> <SEP> glass <SEP> bres <SEP> 60 <SEP> 125 <SEP> 10 <SEP> 0.328
<tb>
<tb>
<tb>
<tb>
<tb> A1203 <SEP> 90 <SEP> 300 <SEP> 16 <SEP> 0.304
<tb>
<tb>
<tb>
<tb>
<tb> TiO2 <SEP> 60 <SEP> 300 <SEP> - <SEP> 1.078
<tb>
<tb>
<tb>
<tb> Zno <SEP> 60 <SEP> 300 <SEP> - <SEP> 0.426
<tb>
<tb>
<tb>
<tb>
<tb> MgO <SEP> 60 <SEP> 135-- <SEP> 0.770
<tb>
<tb>
<tb>
<tb> .bentonite <SEP> Wyoming <SEP> 60 <SEP> 150 <SEP> - <SEP> 1,

  004
<tb>
<tb>
<tb>
<tb> Calcine <SEP> T <SEP> 60 <SEP> 175 <SEP> - <SEP> 0.447
<tb>
<tb>
<tb>
<tb>
<tb> (, elite <SEP> 60 <SEP> 125 <SEP> - <SEP> 0.379
<tb>
<tb>
<tb>
<tb> Slate <SEP> red <SEP> pulverized <SEP> 60 <SEP> 150 <SEP> - <SEP> 2.28
<tb>
<tb> sée
<tb>
<tb>
<tb>
<tb>
<tb> PBO2 <SEP> 60 <SEP> 200 <SEP> 0461
<tb>
 
In molding the above product, it is desirable to apply to the walls of the mold an agent to facilitate removal of the molded product upon expiration of the final heating stage. Short wall mold chroma sheets were used with zinc stearate as the mold lubricant.



  Cellulose acetate, dissolved in acetone, can be applied with a brush or sprayed against the walls in place of the stearate and used as a lubricant, but in this case the product does not come off as well as admitted. stearate.



   The time required for the mixture of high molecular weight siloxane, peroxide and filler to solidify in the mold depends on the amount of peroxide added and the thickness of the section of the mold. In general, when the siloxane is in the form of a gel, it is referred to employ from 2 to 6 parts of peroxide. The time required, for a section of about 31 mm. under these conditions, varies

 <Desc / Clms Page number 34>

 
 EMI34.1
 from half an hour to an hour. When the tubing temperature is raised to more than 160t, solidification is faster with a corresponding reduction in the mechanical strength of the product.

   The molded products, which solidified on heating to 150 C during a denial to a
 EMI34.2
 hour can be heated to 250 C. The da raiteacnt effect continues and results in improved mechanical properties of the final product.



   In general, the products obtained following the procedures
 EMI34.3
 ee:, zt> lesl3-1f are extremely resistant to water, oil, high and low temperatures. We have noted that a product containing 53 jii of allant co: u: ec lw 1 "loses only 4.4) of its weight after 22 hours 8, 250 C., without undergoing any damage in its dimensions or its hardness Another product containing 0.1 asbestos is held at c.4uU-U for 6 hours without disintegrating.3iô-ene after 100 hours 2- 2000G the products keep their pressureability.

   When immersed in water and oil for 85 hours, they show little or no swelling. They are far superior to ordinary rubber in keeping their low temperature properties.

   A molded product prepared by an initial treatment
 EMI34.4
 of 8500 cs viscosity dimethylsilicone with 2;,; by weight of bensoyl peroxide and then ground with; a weight of 6 ::.: a1 of iron oxide and an additional 6 i0 of peroxide and,:. oul (3 a 150i; "retains its fle: mability and resistance -7âU. while a piece of rubber Ordinary hardened for the same time: ps Even after two hours at -780u the siloxane product was still flexiole Due to the properties mentioned above, the following products /;

   the invention are ideally suited for use at extreme temperatures as gaskets, such as washers,

 <Desc / Clms Page number 35>

 housing masses for capacitors operating at high temperatures, coverings for fasteners exposed to extreme temperatures, flexible housings for high temperature castings, insulated jumper wires for motors, ignition cables, etc. GB Thanks to the high heat resistance and the retention of their mechanical properties such as flexibility, compressibility, etc., these products are unique in these fields of application.

   It is also possible to prepare coatings with these organopolysiloxanes by mixing different amounts of fillers and 4-6% of an aromatic acyl peroxide. Mixing is preferably carried out in a three-roll color mill. The mixture obtained is then applied either with a spray gun or by extension using a roller or using a brush. It is advisable to subject the coated layer for half an hour at 110 C (when benzoyl peroxide has been used) in the absence of oxygen to # maintain a resistant and non-sticky coating. . This treatment can be carried out successfully in a CO2 atmosphere or even under water.

   The resulting treated films are flexible and resist when heated to @ 50 ° C. for more than 250 hours without appreciably changing properties. When these films are applied to metal, they also protect the metal surface from oxidation, even when heated to 2500C. these molding compositions with or without fillers can also be applied to fiberglass tape to form after 15 mimits at 125 ° C. an electrically insulating tape, tacky, partially treated,

   which can be wrapped around a metallic conductor and then treated at 125 ° C. in the absence of air for 45 minutes to form an insulating, non-sticky rubber material. It is necessary to attract here

 <Desc / Clms Page number 36>

 
 EMI36.1
 attention to the fact that these -Nē- ininal treatment times are much more expensive and that the treatment temperatures are much lower than those applied so far during use: 3'Ur; ûk ": U-S11U xJ.Yl '?., S co., flexible insulating-coverings.}': abi tuel1cule nt it .is necessary to obtain a wire :; f1exiole and not colla..t, with a o8.nosiloxanel resin to process the resin at a temperature of e 20 ° C :, or higher and for at least several hours.

   By benzoyl peroxide eukolol and other arotnatic acyl peroxides, the final treat-itent ars has been considerably shortened and the tempe-
 EMI36.2
 significantly reduced final processing time, a (; on-
 EMI36.3
 important tribution to the commercial development of 0 l'j <: lnO- s 110: -: '::', 18S cocliae insulating materials for electricity being
 EMI36.4
 thus achieved. It is evident that the invention provides a new
 EMI36.5
 process for P01 ': llériser! partially, or cO> ü "Jlet2- dehydrated gold:.; ano-silox8.nes which contain a11: y1es radicals attached directly to silicon by ia - '> one-siliciuli bonds.

   Among the or; ano-si1..ox,; u18;] ::. 1eútio: més above which fall within the scope of the invention, the following have been found to be particularly suitable because of the stability unusual to heat ootenus products: lower alkylsiloxanes CO, / Ù8 132, it; ¯vr1-, età) -1-,;> ro;> j; 1-, butyleiloxanes etc,; lez phenyl- alky1si 1 () x'.n8s, (; 0,, 1, .. 8 the phenyl-cicthyla, piar¯ß1-; t:? s-lailo- V 8i panes, the l1 (xD, or: : sanocli8ilo.X8.nes, coi-1.-e nx 1 '1.1e; o,! J (., t'lj-YSi- 10' :: lnG. Ete P: '.' 'i; i T: : '' T 0: S, 1. Process for polymerizing a U .. '", -., NU-S11U: 1éèYlC whose

** ATTENTION ** end of DESC field can contain start of CLMS **.


    

Claims (1)

EMI36.6 organic substituents consist essentially of radi- <Desc / Clms Page number 37> Hydrocarbon cals attached to silicon by carbon-silicon bonds, at least some of said hydrocarbon radicals being alkyl radicals, characterized by the treatment of the organosiloxane with a diacyl peroxide containing at least one / acyl radical aromatic participating in the reaction: 2. The method of claim 1, wherein the organosiloxane is a liquid and wherein the reaction is continued, until an increase in viscosity is obtained " 3. A process according to claim 2, wherein the reaction is carried out at a temperature above the decomposition temperature of the peroxide and in the absence of oxygen. 4. A process according to claim 3, wherein the hydrocarbon radicals are lower alkyl radicals. 5. A process according to claim 3, wherein the hydrocarbon radicals are lower alkyl radicals and phenyl radicals. 6. A process according to any of claims 1-5, wherein the aromatic acyl peroxide is benzoyl peroxide, the reaction temperature being above 100 ° C. 7. A process according to any of claims 2-6, wherein the treated orano-siloxane essentially comprises the structural unit, which repeats, R-Si-O-, in R in which R is an alkyl radical and R 'is a monovalent hydrocarbon radical attached to silicon through a carbon-silicon bond. 8. A method according to either of claims 3 and 7, wherein the organosiloxane is a liquid dialkylsilicone, / 1 It <Desc / Clms Page number 38> 9, Process according to either of the claims EMI38.1 3 and 7, wherein the orS2.l1o-siloxal1e is a 2l'c'l.) Jer: ", - 'liquid ilisone. EMI38.2 10. Proceed according to either of the claims 6 and 7, wherein the organo-si10xane is # 1 di ..:. :, ', 1,, 1 silicone. EMI38.3 11. A process according to either of: Evolutions 1-10, wherein the amount of dUt71 peroxide added to the siloxane all at once during each treatment. EMI38.4 is less than 5% by weight of the siloxane. 12. Proceed according to either of claims 1 and 3, in which an orS8.no-) olysiloxane is treated which comprises on average between 1.75 and 2.25 radicals. EMI38.5 hy-trocarbons per silicon atom and in which are present at least 40 laol% of substituted biorcanu-silicon oxide units of formula RR'SiO, in which EMI38.6 Il and R 'are alltyleq radicals the treatment of said polysiloxane with the diacyl peroxide being continued EMI38.7 8, reaction temperature until a solid, rubbery and cohesive material is obtained. 13. The method of claim 12, in EMI38.8 in which the polysiloxane is an methylsiloxane having appro-: i,: ativer.ient two methyl radicals per silicon atom and in which the peroxide is benzoyl peroxide. 14. Process according to either of Claims 12 and 13, in which the treatment is continued only until a composition which is not very fluid at room temperature is obtained, said composition being intimately mixed with a filler resistant to heat and with an additional amount of peroxide, and in which said mixture is then heated until a solid, rubbery and coherent material is obtained <Desc / Clms Page number 39> 15. A method according to claim 14, applying to a gel an organopolysiloxane, wherein the gel is intimately mixed with the heat resistant filler water and a small proportion of diacyl peroxide, the resulting mixture then being heated. until a solid, rubbery and cohesive material is obtained. 16. The method of claim 15, characterized in that it consists in mixing a liquid dimethylsilicone with a small proportion of benzoyl peroxide to heat the mixture beyond 100 C until it turns into a gel, at grind the said Gel with; the heat-resistant filler and about 2 to 6 percent by weight of benzoyl peroxide, (based on the weight of the gel) and then heating the resulting composition to above 100 ° C. substantially in the absence of oxygen until a rubbery, coherent and non-sticky product is obtained. 17. The method of claim 16, wherein the gel is ground to a polyvalent metal oxide. 18. Polymerized organosiloxanes, produced by the manufacturing process described in the foregoing and claimed in any one of claims 1-11. 19. Organo-solysiloxane of high molecular weight, not very fluid at room temperature and whose organic substitutes consist essentially of monovalent hydrocarbon radicals attached to silicon by carbon-silicon bonds, in which there are on average between 1.75 and 2.25 of said hydrocarbon dicals per silicon atom and in which at least 40 mol percent of substituted biorganosilicon oxide unit of formula RR'SiO, in which R and R 'are alkyl radicals ,, <Desc / Clms Page number 40> are present as well as a small proportion of a diacyl peroxide comprising at least one aromatic acyl radical, when the organopolysiloxane is obtained according to the manufacturing process described and claimed above. 20. A rolling composition having as a characteristic component an organopolysiloxane produced by the process described and claimed in either of claims 12-17. 21. The composition of claim 20 containing an inorganic heat resistant filler. 22. Electrically insulating tape, consisting of a fiberglass tape impregnated with the rubbery product of the reaction between a high molecular weight dimethylilione and benzolyl peroxide, produced by the method described and disclosed. in either of claims 12-17. 23. An electrical conductor, consisting of a metallic base member having a coating consisting of a rubbery product resulting from the reaction, entered a high molecular weight dimethylsilicone and benzoyl peroxide produced by the described process and returned. - stated in one or the other of claims 12-17. 24. Processes for polymerizing organosiloxanes in substance, as described and specified by any of Examples 1 to 12 herein set forth. 25. A process for preparing organosilicone compositions, in substance, as described and specified by each of Examples 13-16. ,He