CA1123849A

CA1123849A - Alkoxysilicon materials and method for making

Info

Publication number: CA1123849A
Application number: CA331,767A
Authority: CA
Inventors: James A. Cella; Tyrone D. Mitchell
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1978-07-24
Filing date: 1979-07-13
Publication date: 1982-05-18

Abstract

ABSTRACT OF THE DISCLOSURE
Sllyl ethers of 1,3-dicarbonyl cyclic compounds, such as methyl tris-5,5-dimethyl-cyclohexen-2-one-3-yloxy silane can be made by effecting reaction in the presence of an acid acceptor between an organo halosilane and a 1,3-dicarbonyl cyclic organic compound, for example, 5,5-dimethyl-1,3-cyclohexane dione. The silyl ethers are useful as vulcanizing agents for silanol terminated polydiorganosiloxanes. The curing time of the siloxanes can be varied according to the organo group of the organo-halosilane. When this group is C(1-3) alkyl relatively rapid cure results. When the group is C(4-12) alkyl or alkoxy, slower cure times result.

Description

~ ~3~9 RD-11,115 ALKOXYSILICQN MATERIALS AND METHOD FOR MAKING

The present invention relates to certain alkoxysilyl ethers of 1,3-dicarbonyl cyclic organic compounds and a method for making such materials.
In accordance with the present invention, it has been discovered that silyl ethers of the formula _ O

Rl - C / \ ~ X ) (R)aSi - 0 - C (Y)c 4-a where R is a C(l 13) monovalent organic radical, a has a value of 0 to 2 inclusive and Rl, X, Y, Z, b and c are defined below, can be used as curing agents with silanol terminated organopoly-siloxanes to produce moisture curable compositions. Experience has shown that the moisture curable compositions made with the above silyl ethers often cure exceptionally fast and reduce the usable worklife of the moisture curable organopolysiloxane com-positions. E~forts to extend the cure rate led to the develop-ment of silyl ether substituted with R radicals in the form of C(4 12) alkyl radicals. However, the synthesis of such silyl ethers having long chain alkyl radicals is often uneconomical and further limits the utility of such silyl ethers.
Also in accordance with the present invention, it 2Q has been discovered that certaln alkoxysilyl ethers can similarly be used as curing agents. These alkoxysilyl ethers have the formula ~ ~3~ RD-11,115 (1) ~Rl C/ \~X

(R)d (R )e Si O - C (Y) ~_ _ 4-d-e , where R is a C(1_13) monovalent organic radical, Rl is selected from hydrogen, halogen and R, R2 is a C(l 8) alkyl radical, X and Y are divalent radicals selected from -O-, -S-, and -N- , Z is a divalent C(l 13) organic radical selected from alkylene, cycloallcylene, arylene and a fused ring structure, b and c are equal to O or 1, R3 is selected from hydrogen and R, d is a whole number having a value of from O to 2 inclusive, e is an integer having a value of from O to 3 inclusive and the sum of d + e has a value of from 1 to 3 inclusive.
Radicals included by R of formula (1) are aryl radicals and halogenated aryl radicals, such as phenyl, chlorophenyl, xylyl, tolyl, etc~; aralkyl radicals, such as methyl, ethyl, propyl, chloromethyl, butyl, vinyl, etc.; cyclo alkyl, such as cyclohexyl, cycloheptyl, etc. Radicals included by R2 are, for example, methyl, ethyl, propyl, butyl, pentyl, hexyl, etc.
In formula (1), where R and R2 can represent more than one ,~

... .

RD 11,115 radical, these radicals can be the same or different.
The silyl ethers of formula (1) can be made by effecting reaction under substantially anhydrous conditions between an organo-halosilane of the formula,

(2) (R)d(R )eSiQ4~d-e where R, R and d are as previously defined and Q is a halogen radical, and a cyclic 1,3-dicarbonyl compound of the formula, C

Rl -C/ \ (X )

(3) ¦¦ , b HO C (Y~c in the presence of a base catalyst where R , X, Y, Z, b and c are as previously defined.
There are included within the organohalosilanes of formula (2) compoundshaving the formulas, CH3Sicl3 ; ~ 3 i ~ SiC13 C2H3SiC13 ; CH3 Si C12 ; CH2=CH Si C12 ;

_ Si C12 ; CH3 Si Cl 1 CH = CHSi Cl etc.

O O
/C\ _ C

CH3-Si ~ / 2112 25 1 \ / 2 The cyclic 1,3-dicar~onyl compounds of formula ~3) include cyclohexane-1,3-dione, isopropylidene malonate, 3-hydroxycourmarin, 5,5-dimethylcyclohexane-1,3-dione, 2-methylcyclopentane-1,3-dione, 2-bromo-cyclohexane-1,3-dione, 5,5-dimethyl-3-keto-valerolactone, N-phenyl-3-keto-butyrolactam, etc.

RD 11~115 Among the silylethers of formula (1) there are included C~13-3~ ~ 0-C~ ~H2 ) CH33~ ~ 0-C O ~
OCH3 H2 \C CH3 3Cu2 ~ 2 ;

3i ~ ~C\ ~H2) CH2~CH3i ~ C
OCH3 ~~~C OCH2CH2CH3 C
H2 H2 ' H2 H2 CH3_3i~O-C ~) )C7H143~-C/_C~CH2) OCH2CH2CH3 \C - C 2 ; OCH3 H2 CH3 ic c' (CH O) Si ~ O C~ ~H

CH~3 ,p CH2=CH-Si ~ O-C C~2 ) OCH3 ~ - ~ 2 , etc.

~ RD 11,115 In the practice of the invention, the silyl ethers of formula (l) can be made by effecting reaction under substantially anhydrous conditions between 1-4 mols of the 1,3 dione of formula (3), per mole of the organohalosilane of formula (2), to insure that there is at least a stoichio-metric equivalent between the hydroxy of the 1,3-dione and the halogen attached to silicon of the organohalosilane.
Reaction between the 1,3-dione and the organo-silane is effected in the presence of a basic acceptor, such as organic amine, for example, triethylamine, pyridine, etc. Reaction can be facilitated by use of a non-polar nuetral organic solvent, such as toluene, benzene, hexane, pentane, chloroform, etc., at temperatures in the range of from 0C to 150C. During the reaction, the mixture can be agitated such as by stirring, etc. The mixture then can be filtered of amine salts and the filtrate stripped of organic solvent.
As will be apparent to those in the art, the organosilanes of ormula 2 wherein e has a value of other than 0 may be prepared by effecting reaction under substantially anhydrous conditions between an aliphatic alcohol of the formula

(4) R OH
and an organohalosilane of the formula

(5) Rd_e SiQ4_(d-e) where R, R2, Q, d and e are as previously defined.
Included within formula 4 are aliphatic alcohols such as CH30H; CH3CH20H; (CH3)2CHOH;
CH3(CX2)30H; ~CH3~3CCH20H; (CH3)3COH;

O CH2OH ; etc.

.

~ 3~ RD 11,115 Since the reaction medium for effecting this reaction may be identical to that previously described for effecting reaction between the organohalosilane of formula (2) and the 1,3 dione oE formula (3), it will be appreciated that there is no necessity to isolate the intermediate alkoxy substituted halosilane prior to its further reaction with the 1,3 dione. Also, if desired, the 1,3 dione and aliphatic alcohol may be reacted simultaneously or sequentially with the organohalosilane of formula (5), as the order of addition of the various reactatns is not known to be critical.
The principal utility for the silyl ethers of formula 1 is in the formation of moisture curable, one package organopolysiloxnaes. Such siloxanes may be simply prepared in the manner generally known to those in the art by adding a suitable quantity of the silyl ether of formula (1) to a silanol end stopped polysiloxane, for example having a formula

(6) HO - F s 1 o ~ H
R' n wherein R' is a hydrocarbyl group such as alkyl r alkenyl or aryl or mixtures thereof, or a substituted hydrocarbyl group such as organoalkyl, fluoroalkyl, haloaryl etc.
Suitable such groups are methyl, ethyl, propyl, butyl, pentyl, vinyl etc., cyclopentyl, cyclohexyl~ cycloheptyl, etc., phenyl, tolyl, xylyl, benzyl, phenyl, ethyl etc., organoethyl, organopropyl etc., fluoropropyl, chloro-phenyl etc. Generally, for purposes of economy, R' will be methyl and or phenyl, although other groups may be more desirable for special purposes as will be known to those in the art.

RD 11,115 Moisture curing core package organopolysiloxanes prepared from silyl ethers of formula (1) wherein (e) has a value of zero are found to cure very rapidly. One manner of extending the core rate has been found when usiny silyl ethers of the above type, and that is by restricting the the radicals R to C(4 12~ aclyl radicals such as butyl, pentyl, hexyl, heptyl, octyl, noryl, decyl etc. Extended cure time is preferably achieved by using silyl ethers of formula tl), as these latter compounds are more economically p p d than the C(4_12) alkyl homologues earlier referred to.
In the practice of the invention, the curable organopolysiloxane compositions of the present invention can be made b~ mixing 0.5 to 50 parts of the silyl ether of formula (l) per 100 parts of the silanol-terminated organopolysiloxane, under substantially anhydrous conditions.
The curable compositions may also comprise fillers, such as for example, titanium dioxide, zirconium silicate, silica aerogel, iron oxide, diatomaceous earth, fumed silica, carbon black, precipitated silica, glass fibers, polyvinyl chloride, ground quartz, etc. The amounts of filler used can obviously be varied within wide limits in accordance with the intended use. For example, in some sealant appli-cations, the curable compositions of the present invention can be used free of filler. In other applications, such a the employment o the curable composition for making binding material, such as 700 parts or more of filler, per 100 parts of organopolysiloxane c~n be employed. In such applications, the filler can consist of a major amount of extending materials, such as ground quartz, polyvinyl-chloride, etc., or mixtures thereof, preferably having an average particle size in the range of from ahout 1 to 10 a~
- R~ 11,115 microns.
The order of addition of the various ingredients is not critical. Eor e~ample, the curing agent can be mixed directly with the silanol-terminated organopolysiloxane, followed by the addition of filler, or the curing agent can be added to the mixture of filler and the silanol-terminated organopolysiloxane, etc. Optimum results have been achieved, if the resulting mixture has not more than 100 parts of water, per million parts of mixture, Preferably mixing is accomplished at a temperature between 20C to 80C.
After the curable organopolysiloxane composition is made, it can be stored for a substantial period of time if properly protected from moisture. The curable organopolysiloxane composition can remain in a fluid curable state for periods of two years or more if maintained at temperatures to 60C under substantially anhydrous conditions.
In order that those skilled in the art will be better able to practice the invention, the following examples are given by way of illustration and not by way of limitation. All parts are by weight.
Exa~ple 1 A solution of 15.1 parts of 2-methylcyclohexane-1,3-dione in about 500 parts of dry toluene was refluxed to effect the removal of water from the mixture by azeotropic distillation. ~here was added to the resulting solution, ater it had been allowed to cool, about 15 parts of dry triethylamine followed by 7.3 parts of methyltrichlorosilane.
The resulting mixture was then stirred for two hours. The mixture was filtered to effect the removal of triethylamine hydrochloride and then stripped of solvent. There was obtained 15.4 parts of a brown solid which was a yield of 95~. Based on method of preparation, the product was methyl-tris(2-methyl-1,3-cyclohexanedione)silane having the formula, -` ~3 ;~

RD il ,115 _ O . .

CH3Si - - \ CH2 3 The identity of the product was further confirmed by its NMR
spectrum. -A moisture curable organopolysiloxane composition was prepared by blending under substantially anhydrous condi-tions, 6 parts of the above 1,3-dicarbonylsilyl ether, lO0 parts of a silanol-terminatèd polydimethylsiloxane having a viscosity of abouL 35,000 centipoises at 25C and a hydroxy content of 0.09% by weight, 20 parts of fumed silica and ~05 part of dibutyltindilaurate. The organopolysiIoxane composition was substantially odorless and cured to a tack-free state when it was allowed to rest under atmospheric conditions for abou~ 2 hours. A complete cure was achieved in about 20 hours under atmospheric conditions. A copper substrate coated with the same moisture curable organopolysiloxane and l~eld at 90V/o relative hum-idity for 2 weeks was found to be substantially free of corrosion.
~xample 2.
The procedure of Example 1 was repeated, except that in place of 2-methylcyclohexane~ dione, there was used cyclo-hexane-1,3-dione. Based on method of preparation, there was obtained a 1,3-dicarbonylsilyl ether of the formula, _ g_ , RD 11,115 - ~C~ ~ .
. H-C IH2 CH3Si- CH2 Its identity was confirmed with NMR.
It was found that the resulting moisture curable organopolysiloxane composition made in accordance with the pro-cedure of Example 2, produced a substantialIy odorless, tack-free elastomer after 15 minutes exposure to atmospheric con-ditions, while a completely cured elastomeric product was obtained in only.3 hours.
Example 3.
There was added 151.25 parts of dodecyltrichlorosilane to a stirred solution of 210 parts of cyclohexan-1,3-dione and 156.5 parts of triethylamine in 3,140 parts of dry toluene. The mixture was stirred at reflux for 1 hour and Eiltered. There was obtained 263 parts of product representing an 86ViOyield.
Based on method of preparation, the product was a`l,3-dicarbonyl-silyl e~her of the formula, ~ /C\ ~ .

C12H25Si - \ C / ~ 3 . A mixture of 6 parts of the above 1,.3-dicarbonylsilyl-ether and 100 parts of silanol terminated polydimethylsiloxane was prepared as described in Example 1. The resulting room -- 10 -- .

~ 3 ~ ~ RD 11,115 temperature vu:Lcanizing composition was comp~red to the room temperatur~ compositlon of Example 2 with respect to how long the mixtures were workable after being exposed to atmospheric conditions. The"work liP" test was performed by allowing equal parts of the respective room temperature w lcanizing - mixtures to rest'under atmospheric conditions until the curahle mixtures formed a skin while in an aluminum cup. ~he mix-tures were then difficult to stir with a spatula. It was found ~haL the work life of the mixture having chemically com~ined -dodecyl siloxy.units was about 3-5 minutes, while thP
worklife of the methyl-substituted siloxy containing 1,3-dicar- ' bonyl units was approximately 0.5 to 1 minute, This work life test showed that the 1,3-dicarbonylsilylether silàne advantage-ously extended the period of use of the resulting room temper-l5' ature vulcanizing mixture.
Example 4.
There was added 50 parts of methyltrichlorosilane to a mixture of 100 parts of triethylamine, 162 parts of 3-hydroxy-coumarin and about 2100 parts of dry toluene. When the drop-wise addition was completed, the mixture was filtered and the filtrate was stripped of toluene. There was obtained 170 parts - of methyl-tris(3-hydroxycoumarin)silane having the formula, t ~c c~b ~ 3 - The identity of thP above methyl-tris-1,3-dicarbonyl-silane was further confirmed by its NMR spectrum.

RD 11,115 A blend of 5 parts of the silane and 100 parts of silanol-terminated polydimethylsiloxane and 1 part of dibutyltindilaurate formed a tack-free elastomer after about 1 hour exposure to atmospheric conditions.
Example 5 There was added 21~62 parts of anhydrous methanol to 100 parts of methyltrichlorosilane which was stirring under nitrogen. After hydrogen chloride evolution had ceased, 72.5 parts of the resulting clear solution was added dropwise to a stirred solution of 140 parts of 5,5-dimethyl-1,3-cyclohexanedione, 160 parts of triethylamine and 2400 parts of dry toluene.
The mixture was then filtered to remove tri-ethylamine hydrochloride and the filtrate was stripped of solvent. There was obtained 182 parts of methylmethoxy bis-5,5-dimethylcyclohexane-1-one-3-yloxysilane having the formula, o /C\ ~

CH30Si CH2 2 The identity of the 1,3-dicarbonylsilane was confirmed by its NMR spectrum.
A blend of 6 parts of the above 1,3-dicarbonyl-silane, 100 parts of silanol terminated polydimethylsiloxane having a viscosity of about 35,000 centipoises at 25C, 20 parts of fumed silican and .06 part of dibutyltindilaurate 3~

is mixed under substantially anhydrous conditions. A tack-free substantially odorless elastomer is formed in about one hour under atmospheric conditions.
Example 6 The procedure of Example 1 was repeated, except that a variety of aliphatic alcohols were used in combina-tion with methyltrichlorosilane and 5,5-dimethyl-1,3-cyclo-hexanedione to produce a variety of alkoxy-substituted 1,3-dicarbonylsilanes. In instances where methanol was used as the aliphatic alcohol, t~e proportion of mols of methanol per mol of the methyltrichlorosilane was varied to produce methoxy-sbustituted silanes having a range of from about 0.3 to 1 mol of methoxy radicals per mol of the resulting 1,3-dicarbonylsilane. In instances where higher aliphatic alcohols were used, up to about 1 mol of alkoxy per mol of silane was used.
Moisture curable mixtures were then prepared following the procedure of Example 1 with each of the above-described alkoxy-substituted 1,3-dicarbonylsilanes to determine the effect of alkoxy-substitution on the terminal siloxy units in the respective polydimethylsiloxane moisture curable formulations and the length of the alkyl radical fo the alkoxy radical with respect to the length of time required for forming a skin on the surface of the exposed moisture curable organopolysiloxane compositions or "work life". In addition, the tack-free time of the respective moisture cura~le organopolysiloxane compositions was also determined. All of the mositure curable organopolysiloxane compositions were examine while in aluminum cups which were exposed to atmospheric conditions. A mois~ure ~urable organopolysiloxane composition having terminal siloxy units substituted with 1,3-dicarbonyl silyl ether radicals RD 11 ! 115 free of alkoxy radicals was also evaluated.
The follo~ing results were obtained where "alcohol" represents the alcohol used in preparing the 1,3-dicarbonylsilane and "mols" represents the mols of alcohol per mol of methyltrichlorosilane utilized:
Work Life Tack-Free Time Alcohol Mols (min)_ (min) --- 0 0.5-1.0 3-5 methanol 0.3 5 3 methanol 0.5 5 30 methanol 1.0 --- 40 ethanol 1.0 60-120 ---propanol 1.0 " ---isopropanol 1.0 " ---The above results show that 1,3-dicarbonylsilanes substituted with alkoxy radicals are capable of extending the work life of moisture curable organopolysiloxane compositions as compared to 1,3-dicarbonylsilanes free of alkoxy radicals, In addition, the length of the alkyl groups on the aliphatic alcohol also influences the cure characteristics o the resulting ~loisture curable organo-polysiloxane composition having terminal akoxy substituted siloxy units.
Example 7 In accordance with the procedure of Example 1, a mixture of 31.1 parts of ethanol, 100 parts of methyl-trichlorosilane, 190.4 parts of 5,5-dimethyl-13,cyclohexane-dione, 141.4 parts of triethylamine and about 3,000 parts of toluene was employed to produce an ethoxy 1,3-dicarbonyl-silane having the formula, RD 11,115 38~9 H~ ~0 CH -Si ( //C - C

H ¦ ~ CH
~H3 The above ethoxy-substituted silane was utilized with a silanol-terminated polydimethylsiloxane in accordance with Example 5 and there was obtained a moisture curable organopolysiloxane composition convertible to the solid elastomeric state upon exposure under atmospheric conditions.
The above examples are directed to only a few of the very many variables in the practice of the present invention. It should be understood that they are not limitative of the scope thereof, this being defined by the appended claims and equivalents thereof.

Claims

RD-11,115 The embodiments of the invention in which an exclu-sive property or privilege is claimed are defined as follows:

1. 1,3-silyl carbonyl ethers of the formula where R is a C(1-13) monovalent organic radical, R1 is selected from hydrogen, halogen and R, R2 is a C(1-8) alkyl radical, X and Y are divalent radicals selected from -O-, -S- and , Z is a divalent C(1-13) organic radical selected from alkylene, cycloalkylene, arylene and a fused ring structure, b and c are equal to 0 or 1, R3 is selected from hydrogen and R, d is a whole number having a value of from 0 to 2 inclusive, e is a whole number having a value of from 0 to 3 inclusive, and the sum of d + e has a value of from 0 to 3 inclusive.

2. A 1,3-silyl carbonyl ether in accordance with claim 1 wherein e has a value of 0.

3. A 1,3-silyl carbonyl ether in accordance with claim 2 wherein d has a value of 1, and R is a C(4-12) alkyl radical.

RD 11,115

4. The compound .

5. The compound .

6. The compound .

7. The compound .

RD-11,115

8. The compound .

9. The compound .

10. The compound .

11. The compound .

12. A method for making a 1,3-dicarbonylsilyl ether which comprises (1) effecting reaction between an organo-halosilane of the formula, (R)d(R2O)eSiQ4-d-e and a 1,3-dione of the formula, , in the presence of an acid acceptor, and (2) recovering the resulting 1,3-dicar-bonylsilyl ether from step (1), here R is a C(1-13) monovalent organic radical, Rl is selected from hydrogen, halogen and R, R2 is a C(1-8) alkyl radical, X and Y are divalent radicals selected from -O-, -SO, and , Z is a divalent C(1-13) organic radical selected from alkylene cycloalkylene, arylene and fused ring structure, Q is a halogen radical, a is whole number having a value of from Q to 2 inclusive, b and c are equal to 0 or 1, and R3 is selected from hydrogen and R radicals.

13. A method as defined in claim 12 wherein (e) is 0.

14. A method for making an alkoxy-substituted 1,3-dicarbonylsilyl ether which comprises (1) effecting reaction between an aliphatic alcohol, an organohalosilane of the formula (R)a SiQ4-a and a 1,3-dione of the formula, RD-11,115 in the presence of an acid acceptor, and (2) recovering the resulting alkoxy-substituted 1,3-dicarbonylsilyl ether from step (1), where R is a C(1-13) monovalent organic radical, R1 is selected from hydrogen, halogen and R, X and Y are divalent radicals selected from -O-, -S-, and , Z is a divalent C(1-13) organic radical selected from alkylene, cycloalkylene, arylene and a fused ring structure, a is a whole number having a value of from 0 to 2 inclusive, b and c are equal to 0 or 1, R3 is selected from hydrogen and R radicals, Q is a halogen radical.

15. A moisture curable organopolysiloxane composition comprising a silanol end stopped organo-polysiloxane and a 1,3-silyl carbonyl ether as defined in claim 1, 2 or 3.

16. A process of forming a moisture curable organopolysiloxane which comprises admixing a silanol end stopped organopolysiloxane and a 1,3-silyl carbonyl ether as defined in claim 1, 2 or 3.