Bis (alkoxysilyl-vinylene) group-containing silicon compound and production method of same

Abstract

Provided is an organic silicon compound represented by the following general formula (1) ##STR00001##
(wherein R.sup.1 represents either an alkyl group that has 1 to 20 carbon atoms and may have a substituted group or a cycloalkyl group that has 3 to 20 carbon atoms and may have a substituted group; R.sup.2 represents either a hydrogen atom or a monovalent hydrocarbon group that has 1 to 20 carbon atoms and may have a substituted group, and R.sup.2 may be either identical or different; and each a independently represents an integer of 1 to 3). The novel silicon-containing compound of the present invention provides a cured product of a room temperature-curable organopolysiloxane composition that is particularly superior in fast curability.

Claims

1. A method for producing a cured product of a room temperature-curable organopolysiloxane composition, said method comprising curing said composition with an organic silicon compound represented by formula (1): ##STR00015## wherein R.sup.1 represents either an alkyl group that has 1 to 20 carbon atoms and may have a substituted group or a cycloalkyl group that has 3 to 20 carbon atoms and may have a substituted group; R.sup.2 represents either a hydrogen atom or a monovalent hydrocarbon group that has 1 to 20 carbon atoms and may have a substituted group, and each R.sup.2 may be either identical or different; and each a independently represents an integer of 1 to 3.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a diagram showing a .sup.1H-NMR spectrum of a reaction product ([bis (trimethoxysilyl-vinylene) dimethylsilane]) in a synthesis example 1.

(2) FIG. 2 is a diagram showing a .sup.1H-NMR spectrum of a reaction product ([bis (trimethoxysilyl-vinylene) diphenylsilane]) in a synthesis example 2.

MODE FOR CARRYING OUT THE INVENTION

(3) The present invention is described in greater detail hereunder.

(4) <Silicon-containing Compound Terminated by alkoxysilyl-vinylene Group>

(5) The silicon-containing compound terminated by alkoxysilyl-vinylene group which is represented by the above general formula (1) is that having not less than two alkoxysilyl-vinylene bonds on an identical silicon atom (i.e. bis (alkoxysilyl-vinylene) silane compound).

(6) Here, in the above general formula (1), examples of R.sup.1 as an alkyl group having 1 to 20 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, a neopentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, an octadecyl group, a nonadecyl group and an eicosyl group. Examples of a cycloalkyl group include a cyclopentyl group and a cyclohexyl group. Examples of an alkyl group that has 1 to 20 carbon atoms and may have a substituted group(s), include an aralkyl group such as a benzyl group, a 2-phenylethyl group and a 3-phenylpropyl group. Further, all or a part of the hydrogen atoms in any of these (substituted) alkyl groups may be substituted by, for example, cyano groups and/or halogen atoms such as F, Cl and Br. Examples of a substituted group thus obtained include a 3-chloropropyl group, a 3,3,3-trifluoropropyl group and a 2-cyanoethyl group. Among all the above examples, preferred as R.sup.1 are alkyl groups having 1 to 6, particularly 1 to 4 carbon atoms. A methyl group and an ethyl group are more preferred as R.sup.1, where a methyl group is even more preferred in terms of availability, productivity and cost.

(7) R.sup.2 represents a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. R.sup.2s may be identical to or different from one another. Examples of such R.sup.2 include an alkyl group such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, a neopentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, a undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, an octadecyl group, a nonadecyl group and an eicosyl group; a cycloalkyl group such as a cyclopentyl group and a cyclohexyl group; an alkenyl group such as a vinyl group, an allyl group, a butenyl group, a pentenyl group and a hexenyl group; an aryl group such as a phenyl group, a tolyl group, a xylyl group and an -, -naphthyl group; and an aralkyl group such as a benzyl group, a 2-phenylethyl group and a 3-phenylpropyl group. R.sup.2 may also be a group obtained by substituting a part of or all the hydrogen atoms in any of these groups with, for example, cyano groups and/or halogen atoms such as F, Cl and Br. Examples of such substituted group include a 3-chloropropyl group, 3,3,3-trifluoropropyl group and a 2-cyanoethyl group. Among all the above examples, preferred are monovalent hydrocarbon groups having 1 to 10, particularly 1 to 6 carbon atoms. A methyl group, an ethyl group and a phenyl group are more preferred, where a methyl group and a phenyl group are even more preferred in terms of availability, productivity and cost. Each a independently represents an integer of 1 to 3. However, it is preferred that a be either 2 or 3, more preferably 3.

(8) The organic silicon compound represented by the general formula (1) of the present invention is mainly used as a curing agent for a (room temperature) curable composition. Particularly, those having three methoxy groups on an identical silicon atom in a molecule (six in total per molecule) contain a trifunctional alkoxysilane site(s), and are thus useful as curing agents (cross-linking agent) for a dealcoholized silicone RTV (room temperature-curable organopolysiloxane composition).

(9) <Production Method of Organic Silicon Compound Represented by General Formula (1)>

(10) The silicon-containing compound of the invention which has two alkoxysilyl-vinylene bonds on an identical silicon atom can, for example, be easily produced through an addition reaction such as a hydrosilylation reaction between a silane having two ethynyl groups on an identical silicon atom and two alkoxysilanes (hydrogenalkoxysilane). This reaction is expressed by the following formula [1].

(11) ##STR00004##
(In the above formula, R.sup.1, R.sup.2 and a are defined as above.)

(12) As an addition reaction catalyst used when adding alkoxysilane (hydrogenalkoxysilane), platinum group metal-based catalysts such as a platinum-based catalyst, a palladium-based catalyst, a rhodium-based catalyst and a ruthenium-based catalyst are available. Here, a platinum-based catalyst is particularly preferred. Examples of such platinum-based catalyst include a platinum black; a catalyst with a solid platinum being supported on a support such as alumina and silica; a chloroplatinic acid; an alcohol-modified chloroplatinic acid; a complex of a chloroplatinic acid and olefin; and a complex of platinum and vinylsiloxane. These kinds of platinum may be used in a so-called catalytic amount, and may, for example, be used in an amount of 0.1 to 1,000 ppm, particularly 0.5 to 100 ppm in terms of platinum group metal, with respect to alkoxysilanes.

(13) It is desired that this reaction be performed at a temperature of 50 to 120 C., particularly 60 to 100 C., for 0.5 to 12 hours, particularly 1 to 6 hours, and the reaction can be performed without a solvent. However, an appropriate solvent such as toluene and xylene may be used, provided that no adverse impact will be inflicted upon the above addition reaction or the like.

(14) In an addition reaction to silyl-acetylene group (silyl-ethynyl group), a geometric isomer represented by the following reaction formula [2] will, for example, be produced. In such geometric isomer, the production of E isomer (trans isomer) is highly selective and highly reactive. Since there will be no adverse impact on the properties of the silicon-containing compound of the present invention, these geometric isomers need not be separated at the time of use.

(15) ##STR00005##

(16) Specific examples of the organic silicon compound represented by the general formula (1) of the invention include those represented by the following structural formulae.

(17) ##STR00006## ##STR00007##

WORKING EXAMPLE

(18) The present invention is described in detail hereunder with reference to working examples (synthesis examples), reference examples and comparative reference examples. However, the present invention is not limited to the following working examples. Further, in the specific examples below, part refers to part by mass, and viscosity refers to a value measured by a rotary viscometer at 25 C.

Working Example 1

(19) <Synthesis of Silicon-containing Compound Having Two alkoxysilyl-vinylene Groups on an Identical Silicon Atom-[bis (trimethoxysilyl-vinylene) dimethylsilane]>

(20) Diethynyldimethylsilane of 35.0 g (0.323 mol), a 0.5 wt % toluene solution of a chloroplatinic acid (H.sub.2PtCl.sub.6.6H.sub.2O) of 0.10 g and toluene of 50 mL were put into a 500 mL four-necked separable flask equipped with a mechanical stirrer, a thermometer and a dropping funnel, followed by delivering thereinto 83.01 g (0.678 mol) of trimethoxysilane by drops. Later, stirring was performed at 85 C. for 6 hours, followed by performing distillation so as to obtain 106.2 g (yield 90%) of a silicon compound [bis (trimethoxysilyl-vinylene) dimethylsilane] shown below. Next, a .sup.1HNMR chart of this silicon compound was analyzed, and it was confirmed that the silicon compound was the target bis (trimethoxysilyl-vinylene) dimethylsilane (trans:cis=8:1) (compound shown below). This reaction is shown in the following formula [3].

(21) ##STR00008##

(22) The .sup.1H-NMR spectrum data of this compound are as follows.

(23) .sup.1H-NMR (400 MHz, C.sub.6D.sub.6, (ppm)):0.00 (s, 6H), 3.36 (s, 18H), 6.47 (d, 2H), 7.10 (d, 2H)

Working Example 2

(24) <Synthesis of Silicon-containing Compound Having Two alkoxysilyl-vinylene Groups on an Identical Silicon Atom-[bis (trimethoxysilyl-vinylene) diphenyl silane]>

(25) Diethynyldiphenylsilane of 34.9 g (0.151 mol), a 0.5 wt % toluene solution of a chloroplatinic acid (H.sub.2PtCl.sub.6.6H.sub.2O) of 0.10 g and toluene of 50 mL were put into a 500 mL four-necked separable flask equipped with a mechanical stirrer, a thermometer and a dropping funnel, followed by delivering thereinto 38.5 g (0.315 mol) of trimethoxysilane by drops. Later, stirring was performed at 85 C. for 6 hours, followed by performing distillation so as to obtain 56.5 g (yield 88%) of a silicon compound [bis (trimethoxysilyl-vinylene) diphenylsilane] shown below. Next, a .sup.1HNMR chart of this silicon compound was analyzed, and it was confirmed that the silicon compound was the target bis (trimethoxysilyl-vinylene) diphenylsilane (trans:cis=9:1) (compound shown below). This reaction is shown in the following formula [4].

(26) ##STR00009##

(27) The .sup.1H-NMR spectrum data of this compound are as follows.

(28) .sup.1H-NMR (400 MHz, C.sub.6D.sub.6, (ppm)): 3.61 (s, 18H), 6.45 (d, 2H), 7.31 (d, 2H), 7.36-7.55 (m, 10H).

Reference Example 1

(29) Combined were 100 parts of a dimethylpolysiloxane having a viscosity of 5,000 mPa.Math.s, and a molecular chain whose two ends are blocked by hydroxyl groups (or hydroxydimethylsiloxy groups); 4.9 parts of bis (trimethoxysilyl-vinylene) dimethylsilane; and 0.75 parts of tetramethylguanidylpropyltrimethoxysilane, followed by keeping mixing them under a moisture-blocked condition until a uniform level had been reached, thus obtaining a composition.

Reference Example 2

(30) Combined were 100 parts of a dimethylpolysiloxane having a viscosity of 5,000 mPa.Math.s, and a molecular chain whose two ends are blocked by hydroxyl groups (or hydroxydimethylsiloxy groups); 4.9 parts of bis (trimethoxysilyl-vinylene) dimethylsilane; and 1.0 part of an organic aluminum compound which was a mono (dipivaloylmethane) aluminum bis (ethylacetoacetate) chelate having an average structure represented by the following structural formula (2), followed by keeping mixing them under a moisture-blocked condition until a uniform level had been reached, thus obtaining a composition.

(31) ##STR00010##

Reference Example 3

(32) Combined were 100 parts of a dimethylpolysiloxane having a viscosity of 5,000 mPa.Math.s, and a molecular chain whose two ends are blocked by hydroxyl groups (or hydroxydimethylsiloxy groups); 4.9 parts of bis (trimethoxysilyl-vinylene) dimethylsilane; and 0.2 parts of a compound which was an N,N,N,N,N,N-hexamethyl-N-(trimethylsilylmethyl)-phosphorimidic triamide represented by the following structural formula (3), followed by keeping mixing them under a moisture-blocked condition until a uniform level had been reached, thus obtaining a composition.

(33) ##STR00011##

Reference Example 4

(34) A composition was obtained in the similar manner as reference example 1, except that 6.6 parts of bis (trimethoxysilyl vinylene) diphenylsilane was used instead of bis (trimethoxysilyl-vinylene) dimethylsilane.

Comparative Reference Examples 1 to 3

(35) Compositions were obtained in the similar manners as reference examples 1 to 3, except that there were used 4.1 parts of a silicon compound (vinyltrimethoxysilane) represented by the following structural formula (4) instead of bis (trimethoxysilyl-vinylene) dimethylsilane.

(36) ##STR00012##

Comparative Reference Examples 4 to 6

(37) Compositions were obtained in the similar manners as reference examples 1 to 3, except that there were used 3.8 parts of a silicon compound (methyltrimethoxysilane) represented by the following structural formula (5) instead of bis (trimethoxysilyl-vinylene) dimethylsilane.

(38) ##STR00013##

Comparative Reference Example 7

(39) A composition was obtained in the similar manner as reference example 1, except that there were used 4.5 parts of a silicon compound (1,6-bis (trimethoxysilyl) hexane) represented by the following structural formula (6) instead of bis (trimethoxysilyl-vinylene) dimethylsilane.

(40) ##STR00014##
[Measurement of Tack-free Time]

(41) There was measured a tack-free time of each of the compositions obtained in reference examples 1 to 4; and comparative reference examples 1 to 7.

(42) In addition, each of the compositions obtained in reference examples 1 to 4; and comparative reference examples 1 to 7 was pushed out into a sheet-like shape of a thickness of 2 mm, immediately after they had been produced. The sheet-shaped composition was then exposed to an air of 232 C., 505% RH, and left under the same atmosphere for three days so as to obtain a cured product whose properties (initial properties) were then measured in accordance with JIS K-6249. Here, a hardness was measured by a hardness meter which was an A-type durometer described in JIS K-6249.

(43) Further, similar measurements were performed on a product obtained by storing the above cured product in a thermo-hygrostat of 85 C., 85% RH for 7 days. Furthermore, similar measurements were also performed on a product obtained by heating the above cured product in an oven of 150 C. for 10 days.

(44) Table 1 shows the results of reference examples 1 and 4; and comparative reference examples 1, 4 and 7. Table 2 shows the results of reference example 2; and comparative reference examples 2 and 5. Table 3 shows the results of reference example 3; and comparative reference examples 3 and 6.

(45) TABLE-US-00001 TABLE 1 Comparative Comparative Comparative Reference Reference Reference Reference Reference Measurement result Example 1 Example 4 Example 1 Example 4 Example 7 Tack-free time (min) 5 3 60< 60< 60< Initial Hardness 22 25 16 6 24 RTV (Durometer A) 7 days Elongation (%) 105 130 110 235 0.33 Tensile strength 0.45 0.52 0.27 0.19 100 (MPa) Moisture Hardness 10 16 4 1 8 resistance (Durometer A) 85 C./85% RH Elongation (%) 155 165 430 365 120 7 days Tensile strength 0.25 0.27 0.22 0.08 0.15 (MPa) Heat Hardness 20 20 15 12 23 resistance (Durometer A) 150 C. Elongation (%) 140 130 105 100 120 10 days Tensile strength 0.47 0.35 0.23 0.22 0.29 (MPa)

(46) TABLE-US-00002 TABLE 2 Comparative Comparative Reference Reference Reference Measurement result Example 2 Example 2 Example 5 Tack-free time (min) 2 10 15< Initial Hardness 12 4 0 RTV (Durometer A) 7 days Elongation (%) 105 210 430 Tensile strength 0.27 0.15 0.13 (MPa) Moisture Hardness 11 0.5 0 resistance (Durometer A) 85 C./85% Elongation (%) 150 375 530 RH 7 days Tensile strength 0.33 0.16 0.13 (MPa) Heat Hardness 18 15 14 resistance (Durometer A) 150 C. Elongation (%) 125 190 215 10 days Tensile strength 0.45 0.38 0.38 (MPa)

(47) TABLE-US-00003 TABLE 3 Comparative Comparative Reference Reference Reference Measurement result Example 3 Example 3 Example 6 Tack-free time (min) 4 60< 60< Initial Hardness 25 16 8 RTV (Durometer A) 7 days Elongation (%) 100 105 215 Tensile strength 0.46 0.29 0.22 (MPa) Moisture Hardness 15 10 6 resistance (Durometer A) 85 C./85% Elongation (%) 135 165 260 RH 7 days Tensile strength 0.33 0.26 0.25 (MPa) Heat Hardness 26 18 10 resistance (Durometer A) 150 C. Elongation (%) 115 135 100 10 days Tensile strength 0.51 0.31 0.16 (MPa)

(48) As described above, the organic silicon compound of the present invention provides a cured product superior in fast curability and durability, and can thus serve as a curing agent component effective for a room temperature-curable organopolysiloxane composition.

(49) However, the present invention is not limited to the above embodiment. The above embodiment is simply an example; and any embodiment belongs to the technical scope of the present invention, if the embodiment has a composition substantially identical to that of the technical ideas described in the claims of the invention, and brings about the similar function effects.