Патент USA US2406621код для вставки
2,406,621 Patented Aug. 27, 1946 ‘UNITED STATES PATENT OFFICE 2,406,621 7 METHOD OF PREPARING POLYSILOXANE " RESINS James Marsden, Schenectady, N; Y., assignor to ' General Electric Company, a corporation of I ' < v New York No Drawing. Application February 12, 1944,; Serial No. 522.085 8 Claims. (Cl. 260-2) 2 This invention relates to a method of preparing heat-hardenable' polysiloxane resins frequently called silicone resins. It'is particularly concerned with’ an improved method of hydrolyzing methyl silicon chlorides, i. e., methyl. chloro derivatives ing from 4 to 8 carbon atoms, preferably n 455,617, ?led August 21, 1942, and assigned to the butanol, an aromatic hydrocarbon solvent, and an aqueous solution of hydrochloric acid contain ing at least 35 per cent by weight of hydrogen chloride. The concentrated hydrochloric ‘acid the hydrolyzing medium is preferably consider make-up water, thus avoiding the loss of both sol-H ably in excess of that calculated as necessary to vents and acid. of silane. including mixtures thereof with silicon tetrachloride, to form heat-hardenable products. ‘ The application of Robert 0. Sauer, Serial No. 1 I preferably an aromatic hydrocarbon solvent such as toluene, benzene, or xylene, and slowly adding the resultant solution to a two-phase hydrolyzing medium comprising an aliphatic alcohol contain same assignee as the present invention, describes 10 should be present in an amount exceeding that calculated as necessary to provide su?iclent water and claims a process of hydrolyzlng organo-sili to hydrolyze the chlorosilane mixture. The aque con halides, including mixtures thereof, with sili ous or acid phase resulting from the hydrolysis " con tetrahalides, which process comprises form procedure contains upwards of 35 per cent, gen-~ ing a solution of the organo-silicon halides in an inert, nonalcoholic organic solvent such as tolu 15 orally more than 40 per cent, hydrogen chloride in addition to someof ‘the alcohol and aromatic ene and adding the resultant product to a hy hydrocarbon solvent in amounts corresponding to drolyzing medium comprising a mixture of water .7 their solubiilties in such acid solutions. This and a liquid aliphatic alcohol containing at least phase can be‘ continually reused in subsequent four,'but not more than-eight carbon atoms, such hydrolyses generally with the addition of some as n-butanol. The amount of water present in 20 ' hydrolyze the;silicon halide. As a result, there is obtained as a, by-product of the Sauer process a The large quantity of gaseous hydrogen chloride given on‘ during the hydrolysis as a result of the fact that the hydrolysis medium dilute solution of hydrochloric acid containing 25 is always saturated or substantiahy saturated from 15 to 20 per cent, ordinarily about 17 told with HCl maybe recovered in the practically an- v, . per cent, by weight of hydrogen chloride and hydrous state, in which form it is more readily some of the solvents, such as n-butanol and tol usableinindustry. uene, used in the hydrolysis process. - ' y In order that those skilled in the art better may In the commercial producticnof silicone resins 30 understand how the present invention ‘may be carried into effect, the following illustrative ex by the process of the Sauer application, using amplesare given: . . water as a hydrolyzing medium, the disposal of the dilute acid phase formed as a result of the Example 1 hydrolysis represents a serious problem.‘ While there is a limited use'for such dilute solutions of 35 A three-component mixture containing 59.4 molar per cent dimethyl dlchlorosilane, 22.8 hydrochloric acid, the solvents dissolved therein molar per cent methyl trichlorosilane, and 27.8 represent an appreciable economic loss. The present invention is based on my discovery that the hydrolysis of mixtures of methyl chloro molar per cent silicon tetrachloride was dissolved in toluene in the ratio of 90 parts of the chloro silanes (which term as used generally herein is in 40 silane mixture to 30 parts toluene. The resultant solution was slowly added through a dropping tended to include mixtures of methyl chlorosilanes funnel to a mixture of 60 parts n-hutanol, 30 parts with, silicon tetrachloride) containing vsuillcient toluene, and 300 parts concentrated hydrochloric chlorine vattached directly to silicon to form heat acid contained in a 3-necked glass ?ask ?tted with hardenable hydrolysis products can be carried out in‘a saturated hydrochloric acid- solution in the 45 a_ stirrer, a thermometer, and a reflux condenser presence of the solvents employed in the process . of the Sauer application, and ‘that the concen trated acidhphase resulting from the hydrolysis may be reused in hydrolyzing additional methyl containing carbon dioxide-acetone mixture as a refrigerant. The hydrochloric acid employed in this example contained about 37 per cent by weight of hydrogen chloride. The hydrolyzing bath was not cooled by any external means during More speci?cally, I have found‘ 50 that a mixture of methyl chlorosilanes contain» ing an average of more than two hydrolyzable chlorine atoms per silicon atom can be converted the hydrolysis‘ of the chlorosilane. During addi tion of the chlorosilane solution to the hydrolysis medium the temperature of the bath slowly rose into heat-hard'enable polysiloxane resins by dis tov a maximum of about 31 to 32.5“ C. and chlorosilanes. solving the mixture‘ in an inert organic solvent, '55 thereafter gradually dropped to about 25°v (2. due 2,406,621 3 to the evolution or gaseous hydrogen chloride. silicon tetrachloride may be omitted @therei'rom - After all of the chlorosilane solution had been provided the mixture contains sumcient hydro added, the resultant mixture was stirred for 5 lyzable chlorine atoms attached directly to silicon . minutes, allowed to separate into two layers. and > ‘ so that .on hydrolysis, a. heat-hardenable methyl the lower layer containing a 41 per cent solution polysiloxane resin is obtained. or hydrogen chloride in which'some bu'tanol and While n-butanol is the preferred alcoholic com toluene were dissolved wasseparated from the - ponent of the hydrolysis mixture, satisfactory upper resinous layer comprising a solution or the ' silicone resin in the remaining butanol and tolu results may be obtained by the use or other alco hols containing trom 4 to 8 carbon atoms. Exam ene. - The resinous layer was washed with 200 10 ples of such alcohols are isobutyi alcohol, n-amyl parts water and centriiuged to determine the gel > alcohol, secondary amyl alcohol, isoamyl alcohol, content. Based on the weight or the resin, the amount 01' gel formed during hydrolysis was found tertiary amyl alcohol, fuse] oil, z-ethyl butyl alco to be about 0.4 per cent. hol, methyl amyl carbinol, etc. ' What I claim as, new and desire‘ to secure by 1 15 Example 2 A solution of 90 parts of the methyl chloro-' silane mixture employed in Example 1 in 30 parts toluene was slowly added to an agitated hydrolyzing medium consisting of 60 parts bu 20 tanol, 30 parts toluene, and 325.5 parts of the Letters Patent of-the United States, is 1. The method of making polysiloxane resins which comprises dissolving a mixture or methyl chlorosllanes containing an average ’of more than two chlorine atoms per silicon atoms in an arc matic hydrocarbon solvent and slowly adding the resultant solution to a two-phase hydrolysis lower aqueous or acid layer obtained from Exam medium comprisingan aliphatic alcohol contain ple 1. No differences were noted during the ing from 4 to 8 carbon atoms, an aromatic hydro course of hydrolysis in Examples 1 and 2. The carbon solvent, and an aqueous solution of hy resinous layer was separated from the lower 25 drochloric, acid containing at least 35 per cent aqueous layer and'washed with 200 parts water. by weight of hydrogen chloride. I The resin was found to contain about 0.6 per 2. The method of hydrolyzing a mixture or cent by weight of gel based on the weight of the resin. 1 " methyl silicon chlorides and silicon tetrachloride = Example 3 containing an average of more than two chlorine - '30 atoms per silicon atom which comprises dissolv A solution of 300 parts of a methyl chlorosilane mixture having approximately the same compo sition as that employed in Example 1 in 100 parts ing said mixture in an aromatic hydrocarbon solvent and slowly adding the resultant solution to a two-phase hydrolysis medium comprising a mixture of an aromatic hydrocarbon solvent, an parts n-buta-nol, and 1188 parts of the aqueous 35 aliphatic alcohol containing from 4 to 8 carbon atoms and a concentrated aqueous solution of acid phase obtained from a previous hydrolysis hydrochloric acid. ' of methyl chlorosllanes. Fifty parts water was 3. The method or making polysiloxane resins added to the resultant mixture and the hydro ‘which comprises forming a toluene solution of a ' lyzed resin was separated from the aqueous phase and washed with water. The small amount of 40 mixture of methyl silicon chlorides and silicon tetrachloride containing an average of more than gel present therein was removed and the resin two chlorine atoms per silicon atom and hydro was concentrated and pre-condensed in accord- . lyzing said mixture by slowly adding said solu ance with the process described and claimed in tion to a two-phase hydrolysis medium com copending application Serial No. 455,615, ?led Aug. 21, 1942, in the names of James G. E. Wright 45 prising a mixture of toluene, an aliphatic alcohol containing from 4 to 8 carbon atoms, and a con and James Marsden, now Patent No. 2,389,477, centrated aqueous solution of hydrochloric acid. issued Nov. 20, 1945, and assigned to the same 4. The method or making a polysiloxane resin assignee as the present invention. The resin basev which comprises dissolving a mixture of dimeth content during pre-condensation was 25 per cent. The resultant pre-condensed resin had a craze 50 yldichlorosilane, methyltrichlorosilane and silicon toluene was slowly added to a mixture of 200 time at. 300° C._ of 166 hours, indicating that resins hydrolyzed in accordance with the present ' invention may be readily substituted for those tetrachloride in toluene, slowly adding the re sultant solution tov a two-phase hydrolysis me dium comprising toluene, an aliphatic alcohol containing from 4 to 8 carbon atoms, and a hydrolyzed in accordance with prior processes. On continued reuse of the acid phase formed 55 quantity of concentrated aqueous ‘solution of hydrochloric acid exceeding that calculated as during hydrolysis of the methyl silicon chloride, necessary for complete hydrolysis of the chloro it is desirable to replace the water used up by silane mixture, permitting the resultant mix hydrolysis of the chlorosllanes and to replace ture to separate into two layers, separating the the butanol lost to the upper varnish or resin phase. Ordinarily, about 50 parts water shouldv 60 resin phase and thereafter washing said resin phase with water. be added to the used hydrolysis medium for each 5. The method or making polysiloxane resins 300 parts'of chlorosllanes to be hydrolyzed. In which comprises dissolving a mixture of methyl ' Example 3 the water added to the hydrolysis chlorcsilanes containing an average or more than mixture prior to separation of the ‘resin consti ' tutes the make-up water for the subsequent hy 65 two chlorine atoms per silicon atom in an arc matic ‘hydrocarbon solvent and slowly adding the drolysis of additional methyl chlorosllanes. A. large part of the butanol present in the resin ~ resultant :solution to a two-phase hydrolysis me ‘dium comprising n-butanol. an aromatic hydro layer can be recovered during concentration of carbon »solvent, and an aqueous solution of hy the varnish or resin traction. ‘ Wh?e the above examples describe the hy 70 drochloric acid containine at least 35 per cent ‘ drolysis of particular mixtures .of methyl chloro sllanes and silicon tetrachloride, it is tube under stood that the invention is not limited thereto. For example,~some trimethyl silicon chloride may be present in the chlorosilane'mixture and the 75 by weight or. hydrogen chloride. -' ‘ 6. The method of hydrolyzing a mixture con taining dimethyl silicon dichloride and silicon tetrachloride which comprises dissolving said mixture in an aromatic hydrocarbon solvent and 2,400,021 5 . slowly adding the resultant'solution to a two .phase hydrolysis medium comprising a mixture or an aromatic hydrocarbon solvent, n-butanol, and a concentrated aqueous solution of, hydro chloric‘ acid. ‘ ‘ . "I. The method of. making polysiloxane resins Q which comprises forming a toluene solution or a ‘ mixture of methyl‘silicon chlorides and silicon tetrachloride containing an average of more than . '6 ' : 8. The method of making a polysiloxane resin which comprises dissolving a mixture or dimeth yldichlorosilane, methyltrichlorosilane, and sili con tetrachloride in toluene, slowly adding the ‘ resultant solution to a two-phase hydrolysis me dium compr‘sing toluene, n-butanol, and a quan tity of a concentrated aqueous solution of hydro chloric acid exceeding that calculated as neces sary ior complete hydrolysis oi’ the chlorosilane two chlorine atoms per silicon atom and hydro 10 mixture, permitting the resultant mixture to lyzing said mixture by slowly adding said solu tion to a two-phase hydrolysis medium compris ing a mixture v0i.’ toluene,‘ n-butanol, and a con centrated aqueous solution of hydrochloric acid. separate. into two layers, separating the resin phase and thereafter washing said resin phase _ with water. ' ' - . JAMES MARSDEN.