GB2118960A

GB2118960A - Process for producing fluorosilicone polymers

Info

Publication number: GB2118960A
Application number: GB08302363A
Authority: GB
Inventors: Ben Alfred Bluestein; Edwin Robert Evans
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1978-11-13
Filing date: 1983-01-28
Publication date: 1983-11-09
Also published as: DE2945786A1; GB2036770B; GB2118959B; FR2441640A1; GB8302363D0; JPS5580434A; GB2118959A; JPH0244852B2; GB8302362D0; JPS63125527A; FR2443477B1; JPS6317093B2; GB2118960B; GB8302364D0; FR2441640B1; FR2443477A1; GB2036770A

Abstract

A polydiorganosiloxane of 500,000 to 300,000,000 centipoise at 25 DEG C having C10-30 aliphatic hydrocarbonoxy groups at the chain ends, the organo groups being monovalent hydrocarbon or halogenated hydrocarbon radicals, may be obtained by polymerizing a cyclic polydiorganosiloxane with a polymerization catalyst in the presence of the C10-30 aliphatic alcohol. Preferably the siloxanes contain trifluoropropyl and alkyl or alkenyl radicals.

Description

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GB 2 .118 960 A 1

SPECIFICATION

Process for producing fluorosilicone polymers

The present invention relates to fluorosilicone compositions and more particularly the present 5 invention relates to the production of fluorosilicone polymers by the polymerization of fluoro-substituted cyclic polysiloxanes in the presence of certain select chain-stoppers.

The processes for producing diorganopolysiloxane polymers and more specifically high molecular weight diorganopolysiloxane polymers are well known. In the case of alkyl and aryl substituted polymers, the process comprises taking the appropriate diorganodichlorosilane and hydrolyzing it. The 10 hydrolyzate that is obtained is then taken and most of the acid and water removed from it. The

* hydrolyzate is then taken and there is added to it an alkali metal hydroxide. The mixture is then heated at elevated temperatures for sufficient periods of time, so as to preferentially distill the desired cyclic polysiloxanes. Although such a procedure, which is known as a cracking process, produces cyclic polysiloxanes in which the repeating SiO unit occurs from 3 to 10 times most of the cyclic polysiloxanes

15 are cyclotrisiloxane or cyclotetrasiloxane. Further the cracking procedure can be carried out such that the majority of the cyclic polysiloxanes that are formed are either cyclotetrasiloxanes or cyclotrisiloxanes.

When it is desired to produce a diorganopolysiloxane polymer having methyl and phenyl substituents it is desirable to form as much of the cyclotetnsiloxanes as can be formed. Then the 20 cyclotetrasiloxanes are taken in relatively pure form and there is added to them small amounts of a basic equilibrium catalyst and the appropriate amount of chain-stoppers and the mixture of ingredients is heated at elevated temperatures for a period of time so as to produce high molecular weight diorganopolysiloxane polymers, that is polymers having a viscosity of anywhere from 500,000 to 300,000,000 centipoise at 25°C and more preferably polymers having a viscosity of from 1,000,000 to 25 300,000,000 centipoise at 25°C. After the polymerization has reached its highest level the mixture is cooled down, there is added to it a neutralizing ingredient so as to neutralize the basic catalyst and the excess cyclics are removed so as to yield the desired diorganopolysiloxane polymer. It should be noted that such a procedure is traditionally used to make high molecular weight diorganopolysiloxane polymers. However, it can be utilized to produce low molecular weight diorganopolysiloxane polymers 30 such as those having a viscosity of 500,000 to 1,000,000 centipoise at 25°C.

It should be noted that what determines the molecular weight of the final diorganopolysiloxane polymer that is formed during the polymerization reaction is the amount of chain-stopper that is present in the reaction mixture. Such chain-stoppers are usually triorganosiloxy end-stopped diorganopolysiloxane polymers of iow molecular weight such as disiloxanes, trisiloxanes and sofroth. An 35 example of a suitable chain-stopper for such processes is for instance hexamethyldisiloxane.

The amount of such chain-stoppers in the reaction mixture determines the amount of chain-stoppers available to terminate the polymers that are formed from the cyclo polysiloxane and accordingly, this determines the final molecular weight of the diorganopolysiloxane polymer. As can be appreciated, the smaller the relative amount of the chain-stopper, the higher the molecular weight of 40 the final polymer and the more of the chain-stopper there is present the lower the molecular weight of the final polymer. It should be noted that one procedure for making silanol terminated diorganopolysiloxane polymers in the molecular weight range of 1,000 to 100,000 centipoise viscosity at 25°C or more, is to take the appropriate low molecular weight silanol material as a chain-stopper and add the desirable amount of such chain-stopper in a mixture of the desired cyclotetrasiloxanes with the 45 appropriate amount of acid or basic equilibrium catalyst, and equilibrate the mixture to produce the desired polymer. It is undesirable to have any such low molecular weight silanol terminated diorganopolysiloxane polymer .as a chain-stopper for the production of high viscosity diorganopolysiloxane polymers since the presence of silanol groups in such polymers prior to the cure of the composition in the presence of filler results in excessive structuring of the composition such that it

* 50 can become essentially useless. Accordingly, the presence of silanol groups or moisture is undesirable in i> the preparation of high viscosity diorganopolysiloxane polymers for the heat vulcanizable silicone rubber compositions, where the organo groups in such diorganopolysiloxane polymers are selected from alkyl groups and aryl groups such as methyl and phenyl.

Accordingly, it was unexpected that silanol groups could be beneficially introduced into a high 55 molecular weight diorganopolysiloxane polymer containing fluorinated substituent groups. However, with respect to the production of fluorinated substituted diorganopolysiloxane polymers it is necessary to discuss the traditional production of such polymers. Triorganosiloxy end-stopped fluorinated substituted high viscosity diorganopolysiloxane polymers are produced by first taking the appropriate fluor-substituted diorganodichlorosilanes and hydrolyzing them. The hydrolyzate is then taken and its 60 acidity reduced to the appropriate level and the hydrolyzate is separated from excess water. Then there is added to the purified hydrolyzate the appropriate amount of alkali metal hydroxide catalyst and the hydrolyzate is heated at temperatures of about 200°C or more so as to preferentially distill overhead fluorinated substituted cyclo trisiloxanes. In fluorosilicone chemistry it has been found that cyclo trisiloxanes react more readily in forming polymers than do the corresponding cyclotetrasiloxanes. 65 Accordingly, there is taken the appropriately formed fluorinated cyclo trisiloxanes and there is added to

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GB 2 118 960 A 2

them a basic polymerization catalyst with the appropriate amount of triorganosiloxy end-stopped low molecular weight polymers and the resulting mixture is heated at elevated temperatures so as to form the desired diorganopolysiloxane polymer. However, it has been found out that such fluorinated cyclo trisiloxanes polymerize quickly to form the desired high or low molecular weight polymer, so that the 5 traditional low molecular weight triorganosiloxy end-stopped diorganopolysiloxane chain-stoppers 5

whether fluorinated or not do not enter into the cyclo trisiloxane reaction mixture quickly enough. It has been found that such traditional chain-stoppers take from 4 to 6 hours to react appropriately into the cyclo trisiloxane reaction mixture so as to form the desired molecular weight diorganopolysiloxane ,

polymers. Without the slowness of the low molecular weight triorganosiloxy end-stopped chain-10 stoppers either a low viscosity or a high viscosity fluorinated diorganopolysiloxane polymer could be 10 formed within an hour by the equilibration reaction of the fluorinated substituted cyclo trisiloxane. Thus,

if the chain-stoppers could react faster into the fluorinated substituted cyclo trisiloxane reaction mixture a high viscosity polymer having a viscosity of 500,000 to 300,000,000 centipoise at 25°C or preferably having a viscosity of from 1,000,000 to 300,000,000 centipoise at 25°C could be produced as short a 15 time as 1 hour equilibration time. Accordingly, it was highly desirable to find appropriate chain-stoppers 15 for the polymerization of fluorinated cyclo trisiloxanes such that a high viscosity polymer having a viscosity of from 500,000 to 300,000,000 centipoise at 25°C could be produced in as short a period of time as 1 hour. This would result in a more efficient and economical process for the production of fluorinated substituted silicone polymers and in turn in the production of fluorinated silicone elastomeric 20 compositions. In this respect it was desirable that any chain-stopper that was selected for such a process 20 produced a polymer that had as good physical properties as the fluorinated polymers produced by the prior art processes.

According to the present invention, there is provided a process for producing fluorosilicone polymers comprising (1) reacting (a) one or more cyclopolysiloxanes of the formula.

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(R R1SiO)t

25

where each R, or R1 is individually a monovalent hydrocarbon radical or a fluorinated monovalent hydrocarbon radical wherein t is 3 when a fluorinated hydrocarbon group radical is present, (b) a chain-stopper of the formula.

HO

R

i

SiO-■

R-3

H or R6OH

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35

where each R2 or R3 is a monovalent hydrocarbon radical or a halogenated monovalent hydrocarbon radical, s is a whole number from 2 to 50 or R6 is an aliphatic monovalent hydrocarbon atom of at least 6 carbon atoms and (c) a basic polymerisation catalyst, and (2) neutralizing the basic polymerisation catalyst.

In one embodiment of the present invention there is provided a process for producing fluorosilicone polymers comprising (1) reacting (a) a cyclo polysiloxane of the formula.

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(3)

(R R1SiO)t where R and R1 are selected from monovalent hydrocarbon radical, and a fluorinated monovalent hydrocarbon radical and mixtures thereof, t is 3, (b) a chain-stopper of the formula,

R60H

40 where R6 is an aliphatic monovalent hydrocarbon radical of at least 6 carbon atoms, and (c) a basic polymerization catalyst, and (2) neutralizing the basic polymerization catalyst.

This second embodiment of the present invention can be used to produce polymers other than fluorinated diorganopolysiloxane polymers. However, it is particularly advantageous for the production of fluorinated diorganopolysiloxane polymers. Both processes are preferred for the production of 45 fluorinated high molecular weight diorganopolysiloxane polymers, such as polymers having a viscosity of from 1,000,000 to 300,000,000 centipoise at 25°C. In both cases it is preferred that the cyclo siloxane be a cyclo trisiloxane because the advantages of utilizing the novel chain-stoppers disclosed above is especially noted in the equilibration reaction of cyclo trisiloxanes and more specifically in polymerization reactions of fluorinated cyclo trisiloxanes.

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GB 2 118 960 A 3

In the first process for producing diorganopolysiloxane polymers the process is limited to producing fluorinated diorganopolysiloxane polymers. Accordingly, in Formula 1, R is a monovalent hydrocarbon radical which is preferably selected from alkyl radicals of 1 to 8 carbon atoms such as methyl -ethyl silyl, aryl radicals such as phenyl, methyl-ethyl and etc. cycloalkyl radicals such as 5 cyclohexyl, cycloheptyl, etc., and alkenyl radicals such as vinyl, etc., but most preferably the R radicals in 5 Formula (1) are preferably selected from alkyl radicals of 1 to 8 atoms such as methyl and phenyl. In that Formula R1 is a fluorinated monovalent hydrocarbon radical and is most preferably a fluoroalkyl radical such as 3,3,3-trifluoropropyl. In the process, most preferably t is 3, such that the cyclo siloxane is a cyclo trisiloxane.

10 In the Formula (2) of the chain-stoppers, R2 and R3 are selected from monovalent hydrocarbon 10

radicals and halogenated monovalent hydrocarbon radicals such as alkyl radicals of 1 to 8 carbon radicals, aryl radicals such as phenyl, methyl-phenyl and etc., cycloalkyl radicals, alkenyl radicals such as vinyl, allyl and soforth and fluoroalkyl radicals such as 3,3,3,-trifluoropropyl. It is understood that R2 and R3 can both be alkyl radicals or be selected from an alkyl radical and aryl radicals such as methyl and 15 phenyl. However, in the most preferred embodiment of the instant case it is preferred that one of the R2 15 and R3 radicals be an alkyl radical of 1 to 8 carbon atoms or aryl radical such as methyl or phenyl, and in the other radical be a fluoro-alkyl radical such as 3,3,3-trifluoropropyl. In that Formula, s is a whole number of from 2 to 50. Usually by one process of producing such low molecular weight silanol terminated diorganopolysiloxane polymers of the Formula (2) as will be explained below there is 20 obtained a polymer blend such that there is about 70% of a polymer with 3 siloxy units and such that 20 the other 30% of the polymer mixture is composed of disiloxy, tetrasiloxy, pentasiloxy, hexasiloxy,

heptasiloxy, octasiloxy, etc., silanol terminated diorganopolysiloxy polymers.

Accordingly, it is to be understood that even though a single polymer can be utilized in the instant process there also can be utilized in the instant process and is usually utilized in the present invention a 25 mixture of silanol terminated diorganopolysiloxane polymers of the Formula where s has various values. 25 Proceeding now to the process of this invention, the initial procedure which is known in the prior art can be to take the appropriate fluorinated diorganodichiorosilanes and hydrolyze them in water. After these diorganodichiorosilanes have been hydrolyzed in water, the excess water and acid are separated from the hydrolyzate. The hydrolyzate may then be washed with water and a mild base such as sodium % 30 bicarbonate to neutralize the acid. When the acid of the hydrolyzate is below the required level the 30

hydrolyzate is taken and there is added to it an alkali metal hydroxide such as sodium hydroxide at a concentration of anywhere from 1 to 5% by weight and the hydrolyzate mixture is heated at elevated temperatures of above 200°C at atmospheric pressure or a vacuum so as to preferentially convert and distill overhead from the hydrolyzate a cyclo siloxane. There can be distilled overhead from such a 35 hydrolyzate with such a procedure, cyclo polysiloxanes where the number of SiO groups of from 3 to 35 10 with most of the cyclo polysiloxanes being cyclo trisiloxanes and cyclo tetrasiloxanes. Since in the instant fluorinated process it is easier to work with polymerization of cyclo trisiloxanes, this cracking step is carried out so that there is preferentially distilled overhead cyclo trisiloxanes. This is done by keeping the temperature of the cracking vessel at a sufficiently low point so as to boil off the 40 fluorinated cyclo trisiloxanes there are formed while the temperature is not sufficiently high to distill off 40 the cyclo tetrasiloxanes and the higher boiling cyclo siloxanes. Accordingly, utilizing such a procedure, the hydrolyzate can be converted to mostly cyclo trisiloxanes which are distilled off from the hydrolyzate mixture and collected. These cyclo trisiloxanes then form the basic reactant for forming the base fluorinated substituted polymers. It should be noted that the diorganodichlorolsilanes and accordingly 45 the cyclo trisiloxanes usually have in them as the basic substituent groups or siloxy groups in such 45

compounds methyl, 3,3,3-trifluoropropyl siloxy groups, since such groups are the most easily obtained fluorosubstituted cyclo trisiloxanes. Now it is necessary to go into the process for forming such a chain-stopper as adequately setforth in U.S. Patent No. 3853832. However, to paraphrase the disclosure of that patent what is done is to take a cyclo trisiloxane which can be a dimethyl or a diphenyl cyclo 50 trisiloxane as disclosed above or preferably can be a methyl 3,3,3-trifluoropropyl cyclo trisiloxane and 50 there is added to it an equal weight of acetone and 19% of the starting amount of cyclo trisiloxane of distilled water and to this mixture there is added from .1 to 5% by weight of acid activated clay sold by Filtrol Corporation of Los Angeles, California. It should be noted that the acid activated clay acts as a catalyst in the reaction mixture. The resulting mixture is heated to reflux for over 16 hours during which 55 heated process there is added additional amounts of water, the heating temperature being at a range of 55 50 to 75°C. After a total heating time of anywhere from 1 6 to 24 hours, there is obtained a mixture of acetone, the fore-going silanol terminated low molecular weight diorganopolysiloxane polymers of Formula (2), water and clay. The resulting mixture is filtered through Celite*, a diatomaceous earth to take out the clay. The mixture is then heated to strip off the solvent mixture that is the acetone and 60 water. Finally, the mixture is heated in the range of 7"0 to 100°C under nitrogen sparge so as to remove 60 the residual amounts of acetone and water.

•Registered Trade Mark

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GB 2 118 960 A 4

There results in the reaction mixture, the silanol terminated low molecular weight diorganopolysiloxane polymer of Formula (2) in which polymer mixture approximately 70 to 90% of the mixture has three siloxy units and the rest of the polymer mixture is composed of polymers having 2,4,5,6,7 and a trace amount of a polymer having 8 siloxy units. The polymer usually has a viscosity of 5 in the range 100 to 200 centipoise at 25°C and a silanol content of from 5 to 7% by weight. It should be noted that the above is not the only process for forming the silanol terminated chain-stoppers of Formula (2), other processes can be utilized. For instance, diorganodichiorosilanes may be hydrolyzed and the purified hydrolyzate be utilized as chain-stopper in the processes of the instant case. There -should also be noted that it is not required in the silanol chain-stopper of Formula (2) that there be 10 present fluoroalkyl substituent groups. Accordingly a silanol chain-stopper of Formula (2) having only methyl substituent groups or methyl phenyl or diphenyl or having other substituent groups other than fluoroalkyl substituent groups can be utilized as a chain-stopper in the instant process. Further, a cyclo polysiloxane and preferably a cyclo trisiloxane or cyclo tetrasiloxane will work in the present invention. It is preferred that a cyclo trisiloxane be utilized since the fluorinated cyclo trisiloxanes are most preferred 15 for producing both low moleGular weight and high molecular weight fluorinated substituted diorganopolysiloxane polymers. Accordingly, the desired amount of chain-stopper is mixed with the cyclo polysiloxane of Formula (1) and there is added at least 10 parts per million of a basic polymerization catalyst. Most preferably such basic polymerization catalyst is an alkali metal hydroxide such as potassium hydroxide. For instance, note the disclosure of U.S. Patent No. 3,002,951. 20 However, other basic catalysts can be utilized in the process such as alkali metal silanolates, also, various complex types of alkali metal salts which can be utilized as polymerization catalysts in the instant process, in accordance with the prior art. The resulting mixture of ingredients is then heated at elevated temperatures and'temperatures in the range of 120 to 180°C and more preferably 140 to 180°C for a period of time of from 5 minutes to 4 hours and most preferably of from 30 minutes to 1 25 hour to produce a linear fluorinated diorganopolysiloxane polymer, which is silanol end-stopped. The instant process finds utility in producing high viscosity fluorinated substituted linear diorganopolysiloxane polymers. Such polymers have a viscosity of anywhere from 500,000 to 300,000,000 centipoise at 25°C. It should be noted that in the production of such high viscosity fluorinated polymers there is preferably a mixture of at least 400 parts per million of the silanol chain-30 stopper and at least 10 parts per million of the basic polymerization catalyst. More preferably, there is anywhere from 400 to 2,000 parts per million of the basic polymerization catalyst. It should also be noted that even though the polymerization period can vary from 5 minutes to 2 hours and more preferably 30 minutes to 1 hour. At the end of that period of time there is added a neutralization catalyst, a neutralization agent to the reaction mixture. Such a neutralization agent can be a silyl phosphate as 35 disclosed in the patent application of Razzano et al Serial No. 854,562 filed on November 25, 1977. Other neutralization agents may be utilized like chiorosilanes, acetic acid and various other mild acids. The advantage of the silyl phosphate is that it is a buffering agent as well as an acetic neutralizing agent such that back-titration is not necessary to reach a substantially neutral level in the polymerization mixture. After the reaction mixture has been neutralized then the mixture is heated at 40 a temperature of at least 150°C for at least 1 hour to strip off excess cyclics so as to yield the desired polymer. It should be noted that utilizing this procedure there can be obtained the desired polymer with a small amount of volatiles or cyclic polysiloxanes in the equilibration mixture of 5% or less.

It has been found that such silanol terminated fluorinated linear diorganopolysiloxane polymers having a viscosity of anywhere from 500,000 to 300,000,000 centipoise at 25°C and more.preferably 45 having a viscosity varying from 1,000,000 to 300,000,000 centipoise at 25°C may be taken and there may be compounded into them the various types of fillers and specifically from 5 to 300 parts of filler per 100 parts of the base polymer. The filler is selected from silica fillers and extending fillers. Examples of silica fillers and specifically reinforcing silica fillers are fumed silica and precipitated silica and specifically such silicas which have been treated with cyclo tetrasiloxanes as disclosed in U.S. Patent 50 No. 2,938,009 and also such reinforced silica fillers treated with silazanes and diethyl hydroxyl amine. To such mixture of base polymer and filler which are compounded normally in a dough mixer there is added a process aid for instance such as those disclosed in U.S. Patent No. 4,089,833. Such process aids prevent the composition from structuring prior to cure and also from sticking to the compounding mills as disclosed in the foregoing U.S. Patent No. 4,089,833. To these ingredients there may be added 55 various other additives such as oil resistant additives, flame retardant additives such as carbon black and platinum compression set additives such as rare earth octoate and soforth, to the resulting mixture there may be added the desired level such as from .01 to 5% by weight of an organic peroxide catalyst such as dicumyl peroxide, dibenzoyl peroxide and soforth as disclosed in U.S. Patent No. 3,773,817 so as to cure the composition to form a fluoro-substituted silicone elastomer. Such fluoro-substituted and 60 specifically what is known as heat vulcanizable fluoro-substituted silicone rubber compositions form silicone elastomers which have good solvent resistance and are especially useful for that reason.

It should be noted that traditional all methyl phenyl base polymers from which heat vulcanizable silicone rubber compositions are formed in which there is incorporated water or in which the base polymer has silanol groups results in the composition crumbling when it is compounded with filler or 65 structuring so it cannot become compounded. It should be also appreciated that such compositions in

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which there is a peroxide catalyst activated by heating the composition at a temperature above 100°C so as to activate the peroxide catalyst. The present invention can also be utilized to form base polymers which is useful in fluorinated SiH olefin platinum catalyzed compositions such as those disclosed in U.S. Patent No. 4,061,609. It should be noted that in the foregoing process of the instant case that the cyclic 5 siloxane of Formula (1) need not be a pure material but it may be a mixture of cyclo trisiloxanes with 5

cyclo tetrasiloxanes where the cyclo trisiloxanes are the fluorinated substituted siloxanes and the cyclo tetrasiloxanes have vinyl substitution or methyl vinyl substitution. Such cyclo tetrasiloxanes or methyl vinyl cyclo trisiloxanes are present in the reaction mixture so as to introduce vinyl into the final polymer that is formed such that the composition can cure with a peroxide catalyst to form a heat vulcanizable 10 fluorinated silicone elastomer. 10

Although the above process can be utilized with advantage there is encompassed by the instant invention a modification of the above disclosure that there may be reacted in to the foregoing cyclo polysiloxanes or more generally even the non-fluorinated cyclo polysiloxanes of Formula (3), a chain-stopper which is a high polecular weight alcohol of the formula R6OH where R6 is an aliphatic 15 monovalent hydrocarbon radical with at least 65 carbon atoms and more preferably at least 10 carbon 15 atoms such as from 10 to 30 carbon atoms for instance, octadecanol, hexadecanol, tetradecanol, oleyl and soforth. The high molecular weight alcohols find most advantage in being utilized as chain-stoppers in the process for the formation of high viscosity linear diorganopolysiloxane polymers such as those having a viscosity of from 500,000 to 300,000,000 centipoise at 25°C and more preferably having a 20 viscosity of from 1,000,000 to 200,000,000 centipoise at 25°C. These high molecular weight chain- 20 stoppers will be incorporated into the mixture substantially almost as fast as the silanol chain-stoppers of Formula (2). These alcohol chain-stoppers are cheaper to obtain and do not require specialized processes to produce. Such high alcohol chain-stoppers can be utilized both as chain-stoppers in the equilibration reactions in the production of non-fluorinated substituted polymers as well as in the 25 production of fluorinated substituted polymers. 25

Accordingly, in Formula (3) R4 and R5 are selected from a class consisting of monovalent hydrocarbon radicals and fluorinated monovalent hydrocarbon radicals and mixtures thereof where t is 3. As noted in the instant process, the R4 and Rs may be selected from alkyl radicals of 1 to 8 carbon atoms, such as methyl-ethyl, propyl, alkenyl radicals such as vinyl, allyl and etc., cycloalkyl radicals such 30 as cyclohexyl, cycloheptyl, etc., aryl radicals such as phenyl, methyl-phenyl, ethyl-phenyl and etc., and 30 fluoroalkyl radicals of 3 to 8 carbon atoms such as 3,3,3-trifluoropropyl. In addition in the reaction mixture that is of the cyclo polysiloxanes there can be a cyclo trisilozane and cyclo tetrasiloxane or higher cyclo siloxane. Most preferably, the cyclo siloxane is either a cyclo trisiloxane or a mixture of .

cyclo trisiloxanes and cyclo tetrasiloxanes. In the most preferred embodiment of the instant case in the 35 formula of the compound of Formula (3) R3 is an alkyl radical of 1 to 8 carbon atoms such as methyl and 35 R5 is 3,3,3-trifluoropropyl, t is equal to 3. Such a cyclo trisiloxane is mixed with a cyclo tetrasiloxane in which t is equal to 4 and R4 is methyl and R5 is vinyl. These are the type of ingredients that would be necessary to produce a high molecular weight vinyl-containing fluorinated diorganopolysiloxane polymer which would be useful in the preparation of fluoro-substituted heat vulcanizable silicone 40 elastomers. 40

The process for the production of the fluorinated cyclo trisiloxane is the same in this embodiment as it was in the last embodiment. The methylvinyf cyclotetrasiloxanes are produced by the same procedure by utilizing the appropriate diorganodichiorosilanes. The only difference being that in the cracking step the reaction mixture is heated at a higher temperature so as to preferentially distill 45 overhead cyclotetrasiloxanes. By using a modified procedure, the cyclotrisiloxanes thata re boiled are 45 condensed and returned to the cracking pot for re-reaction so as to obtain a maximum overhead distillation of the cyclo tetrasiloxanes. Accordingly, after the appropriate cyclo siloxanes have been obtained, and mixed together at the appropriate proportions there is added the desired amount of the high alcohol chain-stopper which is readily available in the market place. Then there is added the 50 appropriate amount of the basic polymerization catalyst. With respect to the concentration of the chain- 50 stopper, it may be utilized at anywhere from at least 50 parts per million of the high alcohol chain-stopper to up to 2,000 parts per million. At least 10 parts per million of the basic polymerization catalyst and more preferably from 20 to 50 parts per million of the basic polymerization catalyst are utilized. In the production of non-fluorinated polymers there would be utilized solely cyclotetrasiloxanes 55 with a high alcohol chain-stopper and a basic equilibration catalyst such as an alkali metal hydroxide. 55 The resulting mixture is heated at a temperature above 140°C for anywhere from 2 hours to 24 hours until the maximum amount of the preferred high viscosity polymer is obtained. Then the reaction mixture could be cool, the basic equilibration catalyst would be neutralized with a mild acid such as a silyl phosphate or acetic acid and the unreacted cyclics stipped off to leave behind the desired polymer. 60 In the production of fluorinated polymers a fluorinated cyclo trisiloxane would be polymerised along or 60 preferably in combination with the vinyl containing substituted cyclo trisiloxane or methyl-vinyl cyclo tetrasiloxane in the presence of the appropriate amount of alcohol chain-stopper and a basic polymerization catalyst such as potassium hydroxide or a potassium silanolate at the concentration shown below and the reaction mixture heated at a temperature range of 120 to 180°C for a period of 65 time of 5 minutes to 4 hours and more preferably of from 30 minutes to 1 hour. Whereupon after that 65

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period of time the basic polymerization catalyst is neutralized with a mild acid such as the preferred silyl phosphate for the reasons given in the previous embodiment or with a mild acid such as acetic acid. It should be noted that the same basic polymerization catalysts can be utilized in this embodiment as was utilized in the previous embodiment and as disclosed in the foregoing U.S. Patent No. 3,002,951. Note that any high molecular weight aliphatic alcohol can be utilized in the instant process and preferably a high molecular weight aliphatic alcohol having anywhere from 6 to 30 carbon atoms and more preferably having from 10 to 30 carbon atoms. After polymerization reaction is over the reaction mixture is cooled down, a neutralization agent is added and the reaction is terminated in the preferred period of 30 minutes to 1 hour. The reaction mixture is then cooled down and there is added to it a neutralization ingredient for the basic polymerization catalyst such as a silyl phosphate for the reasons setforth previously. Then the unreacted cyclics are removed to leave behind the desired polymer. The unreacted cyclics are removed by heating the reaction mixture at a temperature of 150°C for at least 1 hour. It should be noted that while this second embodiment may be utilized to produce a diorganopolysiloxane polymers of various viscosities, it is preferably utilized to produce high viscosity fluorinated substituted linear diorganopolysiloxane polymers. Accordingly, there is obtained a polymer of a formula,

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il100 ■

R8 «

SiO

R'

R

10

(4)

n where R8, R9 are selected from monovalent hydrocarbon radicals and halogenated monovalent hydrocarbon radicals, R10 is an aliphatic radical of at least 6 carbon atoms and more preferably at least 20 10 carbon atoms or generally from 10 to 30 carbon atoms and n is such that the viscosity of the 20

polymer is from 500,000 to 300,000,000 centipoise at 25°C. Generally, R8 and R9 can be any of the radical or substituent groups given for R4 and R5 in the cyclo trisiloxane of Formula (3) preferably R8 is selected from a mixture of alkyl radicals of 1 to 8 carbon atoms and R9 is 3,3,3-trifluoropropyl and R10 is an octadecyl radical.

25 Such a compound may be taken and preferably one having a vicosity varying from 1,000,000 to 25 300,000,000 centipoise at 25°C and there may be added per 100 parts of the base polymer from 5 to 300 parts of a filler and most preferably a reinforcing silica filler selected from fumed silica and precipitated silica which is desirably treated with cyclopolysiloxanes as disclosed in the foregoing Lucas Patent or treated with silazanes or diethyl-hydroxyl amine as the case may be. To such a mixture of 30 ingredients which is compounded usually in a dough mixer there may be added various and necessary 30 process aids such as those disclosed in the foregoing Simpson Patent and the various other ingredients disclosed above in the first embodiment of this application resulting in a mixture of ingredients that this mixture may then be taken and there may be incorporated into a peroxide catalyst and the resulting mixture is heated at elevated temperatures above 100°C so as to form a fluorinated silicone elastomer 35 which has the solvent resistant advantages noted previously. 35

It should be noted that such fluorinated silicone elastomers formed by the above procedure appear to have as good a physical properties as those produced by the prior art methods. It should also be noted that such fluorinated polymers and dimethyl polymers produced by this process may be utilized in SiH olefin platinum catalyzed compositions such as that of the foregoing U.S. Patent No. 4,061,605. 40 The Examples below are given for the purpose of illustrating the present invention. They are not 40 given for the purpose of setting bounds or limitations to the definition of the instant invention. All parts are by weight.

EXAMPLE 1

A methylfluoropropyl cyclotrisiloxane and octadecanol as referred to in Table 1 below, were put 45 into a pot and the resulting mixture was heated to 135°C and purged with nitrogen to remove traces of 45 moisture. Methylvinyl cyclotrisiloxane and sodium hydroxide catalysts were added and the polymerization started. After 38 minutes the reaction was stopped by removing the hot bath and introducing carbon dioxide gas. The polymer was finally neutralised by mixing in the dough mixer with silyl phosphate. The volatiles were determined as disclosed in Table 1 below. The method for 50 determining volatiles is by heating the polymer in a shallow dish at 135°C and 15 mm vacuum for 45 50 minutes and measuring the loss in weight. The Williams Plasticity of the polymers formed prior to the removal of volatiles and after the removals of the volatiles are shown in Table 1 below. The results are setforth and shown in Table 1.

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TABLE 1

Composition

A

B

C

D

Methyl fluoropropyl cyclic trimer

500

parts parts parts parts

Octdecanol

0.4

0.16

0.051

0.052

parts parts parts parts

Methyl vinyl cyclic trimer

1.53

parts parts parts parts

NaOH (2% solution)

0.57

parts parts parts parts

Volatiles

3.6%

2.3%

2.2%

2.0%

Williams Plasticity

137

198

251

247

Williams after removing volatiles

145

208

266

258

Two polymers were compounded by mixing 100 parts of the~polymer, 3 parts of a dimethyl silanol oil process aid, 4 parts of a high vinyl on chain vinyl gum having 13.5 mole percent vinyl, a process aid, 23 parts of tetramer treated fumed silica filler, and 0.2 parts Red Iron Oxide. The compound ingredients 5 were press cured with 1.6 parts of a 50% by weight active parts of bis(2,4, dichloro-benzoyl) perioxide. 5 These compositions are referred to as Compositions C and D in Table 2 below. The physical properties of these cured compositions which were cured under the conditions shown in Table 2 are as follows:

TABLE 2

Composition

Cure

Hardness

Tensile

Elong.

Tear

347°/22 Comp. Set

C

400°F/4hr

46

1160

550%

92

36

+400°F/70hr

46

1000

480%

86

—

D

400°F/4hr

46

1090

560%

108

EXAMPLE 2

10 Polymers were prepared by the process of the instant case and process of the prior art wherein the 10

process of the instant case utilizes fluoro-substituted silanol chain-stopper. After the polymers were formed by the prior art process and the instant process, the polymer was heated at 350° for 15 minutes in the presence of wet nitrogen which acted as an hydrolysis-agent to increase any tendency of the polymer to degrade. The results are in Table 3 below, which shows the weight loss of the polymer under 15 the above tests. 15

Polymer Williams Plasticity End Group %Wgt. Loss

E

251

—Si(CH3)20H

11.9%

F

281

—Si(CH3)(OH)(CH2CH2CF3)

10.0%

G

332

—Si(CH3)(OH)(CH2CH2CF3)

8.7%

H

250

—Si(CH3)3

12.4%

I

267

—Si(CH3>3

7.3%

F

276

—Si(CH3)3

6.5%

The results in Table 3 indicate that polymers produce utilizing a silanol chain-stopper more

8

GB 2 118 960 A 8

specifically a fluorinated substituted silanol chain-stopper are relatively almost as stable as polymers utilizing a trimethylsiloxy chain-stopper.

EXAMPLE 3

A clean dry vessel was charged with 500 parts (1.06 moles) of methyl 3,3,3-trifluoropropyl 5 siloxane cyclic trimer (FS), 1.43 parts (0.001 moles) of 1,3,5,7-tetramethyM ,3,5,7-tetravinylsiloxane 5 cyclic tetramer (VT), and 0.49 parts (0.001 moles) of 1,3(5-trimethyl-1,3,5 tris (3'3'3'-trifluoropropyl) trisiloxane-1,5-diol. The contents of the vessel are heated to 120—140°C and purged with nitrogen until 25 parts of the trimer is removed to lower the moisture content to <10 PPM. The vessel temperature is adjusted to 140°C, when said temperature is achieved, 0.98 parts of sodium 10 fluorosilanolate is added (provides the equivalent of 0.025 g of sodium hydroxide). The polymerization is 10 carried out with agitation for 8—10 minutes then allowed to remain up to 35 minutes before neutralizing the catalyst with silyl phosphate (equivalent to a 13% solution of H3P04). The polymer is then devolatized at 150—160°C to a volatiles level of 0.8 ± 0.5%. A tough gum with a William Plasticity of 225 was obtained. The polymer has a solution viscosity of 2.112 (2% sol in ethyl acetate at 15- 77°F). The gum when compounded provided good vulcanizate properties. 15>

Formulation Parts

Polymer 100 Polydimethyl contains 13.5 m% vinyl on chain • 4

20 HO-4-Si (ME)2—04g-H 3 20

Fumed silica 23

Rare Earth Octoate 0.2

TS—502 1.6

1. Fumed silica treated with 1,3,5,8-octamethylsiloxane cyclic tetramer 25 2. Bis(2,4-dichlorobenzoyl) peroxide, 50% active paste; 25

*Cadox TS—50, Nowry Chemical Corp., Burt, NY *Luperco CST, Lucidol Div., Pennwalt Corp., Buffalo, NY

Press Cure 10 min. 287°F and Post Bake 4 hrs/400°F

Property

Silanol Stopped

(CH3)3SiO-Stopped

30 Shore A

41

43

Tensile, psi

1076

1145

Elongation, %

670

630

Die C Tear, lbs.

118

102

Comp. Set 22 hrs/300°F

25.0%

25.8%

35 Comp. Set 22 hrg/350°F

39.0%

34.1%

30

35

9

GB 2 118 960 A 9

After Oven Aging 24 hrs/300°F

Property

Silanol Stopped

(CH3)3SiO-Stopped

Shore A

40

44

Tensile, psi

1140

995

Elongation, %

690

590

Die C Tear, lbs.

115

105

Comp. Set 22 hrs/300°F

19.8%

—

Comp. Set 22 hrs/350°F

29.0%

—

Boyshore

40

—

10 EXAMPLE 4 10

A clean dry vessel was charged with 500 parts (1.06 moles) of fluorosilicone trimer, 1.43 parts (0.001 moles) of methylvinyl trimer and 0.61 parts (0.0012 moles) of 1,3,5-trimethyl-1,3,5 tris (3'3'3'-trifluoropropyl) trisiloxane-1,5-diol. The contents of the vessel were heated to 120—140°C and as in Example 1, the system was dried and the vessel temperature adjusted to 140°C. The catalyst sodium 15 fluorosilanolate was added to provide the equivalent of 0.017 parts (0.00042 moles) of sodium \ 5

hydroxide.

The polymerization was terminated after 35 minutes via neutralization with silyl phosphate. The gum was then devoled at 150—160°C to a volatiles content of 0.8 ± 0.5%. A gum with a Williams Plasticity of 258 was obtained. The polymer had a solution viscosity of 2.177 (2% ethyl acetate at 20 77°F). A Brabender reading of 800 meter rams of torque at a shear rate of 40 RPM at 37°C. The gum 20 compounded and cured according to the procedure in Example 3 provided the following physical properties:

Press Cured 10 min. 287°F and Post Bake 4 hrs/400°F Property

25 Shore A 41 25

Tensile, psi 1095

Elongation, % 650 Die C Tear, lbs. 135 Comp. Set 22 hrs/300°F 38% 30 Comp Set 22 hrs/350°F 25% 30

EXAMPLE 5

A clean dry vessel was charged with 210 parts (0.45 moles) of fluorosilicone trimer, 0.6 parts (0.007 moles) of methylvinyl trimer and 0.104 parts (0.0002 moles) of 1,3,5-trimethyl-1,3,5 tris (3',3',3'-trifluoropropyl) trisiloxane-1,5-diol. The polymerization mixture was dried according to the 35 procedure described in Examples 3 and 4 except 10 parts of fluorosilicone trimer was removed. The 35 catalyst 0.007 parts (0.00018 moles) of sodium hydroxide colloided (25—30 micron size) in 1,3,5,7-dimethyl-siloxane cyclic tetramer was added. The polymerization was carried out for 35 minutes; then the catalyst was neutralized and the gum devolatized according to the aforementioned procedure in Example 1. A gum with a Williams Plasticity of 305 was obtained. The gum had a Brabender reading of 40 880 meter grams of torque at a shear rate of 40 RPM and at 37°C. The polymer provided a solution 40 viscosity of 2.541 (2% in ethyl acetate at 77°F).

10

GB 2 118 960 A 10

Claims

CLAIMS 1. A polymer of the formula. R100- R8 I SLO R 10 n where R8, R9 are individually a monovalent hydrocarbon radical or a halogenated monovalent 5 hydrocarbon radical, R10 is an aliphatic radical of at least 10 carbon atoms and n varies such that the viscosity of the polymer varies from 500,000 to 300,000,000 centipoise at 25°C. 2. A polymer as claimed in claim 1 wherein R8 is an alkyl or alkenyl radical, R9 is 3,3,3-trifluoropropyl and R10 an octadecyl radical. 3. A silicone rubber composition comprising (i) a diorganopolysiloxane gum having a viscosity 10 varying from 1,000,000 to 300,000,000 centipoise at 25°C and having hydrocarbonoxy-diorganosiloxy groups at the ends of the polymer chain wherein said hydrocarbonoxy groups are aliphatic hydrocarbonoxy groups having from 10 to 30 carbon atoms and said organo groups are monovalent hydrocarbon radicals or fluorinated monovalent hydrocarbon radicals and (ii) a filler. 4. A composition as claimed in claim 3 wherein component (i) the hydrocarbonoxy groups are 15 octadecanoxy and the organo groups are a mixture of alkyl, alkenyl radicals and 3,3,3-trifluoropropyl. 5. A silicone rubber cbmposition as claimed in claim 1 or claim 3 substantially as hereinbefore described in any one of the examples. 10 15 20 New claims or amendments to claims filed on 13.5.83 Superseded claims 1—5 New or amended claims:— 1—6 20 25 CLAIMS

1. A silicone polymer which is a diorganopolysiloxane having a viscosity of from 500,000 to 300,000,000 centipoise at 25°C and having hydrocarbonoxy-diorganosiloxy groups at the ends of the polymer chain wherein said hydrocarbonoxy groups are aliphatic hydrocarbonoxy groups having from 10 to 30 carbon atoms and said organo groups are monovalent hydrocarbon radicals or halogenated monovalent hydrocarbon radicals.

2. A polymer of the formula,

R100 ■

R8

i

SiO

R-

R

10

n where R8, R9 are individually a monovalent hydrocarbon radical or a halogenated monovalent 30' hydrocarbon radical, R10 is an aliphatic hydrocarbon radical of at least 10 carbon atoms and n varies such that the viscosity of the polymer is from 500,000 to 300,000,000 centipoise at 25°C.

3. A polymer as claimed in claim 2 wherein R8 is an alkyl or alkenyl radical, R9 is 3,3,3-trifluoropropyl and R10 an octadecyl radical.

4. A composition as claimed in claim 1 wherein component (i) the hydrocarbonoxy groups are 35 octadecanoxy and the organo groups are a mixture of alkyl, alkenyl radicals and 3,3,3-trifluoropropyl.

5. A polymer as claimed in any one of the preceding claims further including a filler.

6. A polymer as claimed in claim 1, substantially as hereinbefore described in any one of the examples.

25

30

35

Printed for Her Majesty's Stationery Office by the Courier Press, Leamington Spa, T983. Published by the Patent Office, 25 Southampton Buildings, London, WC2A 1AY, from which copies may be obtained.