Novel Organosilane Compounds

The present invention relates to a novel organosilane compound having a methacryloxy group ##STR2## and at least one alkenyloxy group bonded to the same silicon atom and a method for the preparation of the organosilane compound. The inventive organosilane compound is useful as a coupling agent to improve the adhesive bonding strength between organic and inorganic materials.

The invention provides a novel class of organosilane compounds hitherto unknown or not described in any prior art literatures represented by the general formula ##STR3## in which R.sup.1 is a monovalent hydrocarbon group having from 1 to 8 carbon atoms, R.sup.2, R.sup.3 and R.sup.4 are each a hydrogen atom or a monovalent hydrocarbon group having from 1 to 8 carbon atoms, m is an integer of 3, 4 or 5 and n is a number of zero, 1 or 2. In particular, the invention relates to an organosilane compound of the above given general formula (1) in which R.sup.1 is a methyl, ethyl or phenyl group, R.sup.2 is a methyl or ethyl group, R.sup.3 and R.sup.4 are each a hydrogen atom or a methyl group, m is 3 or 5 and n is zero or 1.

The methacryloxy- and alkenyloxy-containing organosilane compound of the general formula (1) can be readily synthesized by the addition reaction between a corresponding alkenyl methacrylate and a hydrogen-alkenyloxysilane in the presence of a platinum catalyst.

FIG. 1 and FIG. 2 are the infrared absorption spectra of the reaction products obtained in Example 1 and Example 2, respectively.

In the general formula (1) given above representing the inventive organosilane compounds, R.sup.1 is a monovalent hydrocarbon group having from 1 to 8 carbon atoms exemplified by alkyl groups such as methyl, ethyl, propyl and butyl groups, alkenyl groups such as vinyl and allyl groups, aryl groups such as phenyl and tolyl groups and aralkyl groups such as benzyl group as well as those substituted hydrocarbon group obtained by the substitution of halogen atoms, e.g. chlorine atoms, or cyano groups or other substituent groups for part or all of the hydrogen atoms in the above named monovalent hydrocarbon groups. In particular, the group R.sup.1 is preferably a methyl, ethyl or phenyl group although the group R.sup.1 is not contained in the silane compound when the number n is equal to zero.

The symbols R.sup.2, R.sup.3 and R.sup.4 in a molecule of the silane compound may be the same or different from each other and are each selected from the class consisting of a hydrogen atom and monovalent hydrocarbon groups having from 1 to 8 carbon atoms as exemplified by the same hydrocarbon groups as the examples of the group R.sup.1. Preferably, the group R.sup.2 is a methyl or an ethyl group and the groups R.sup.3 and R.sup.4 are each a hydrogen atom or a methyl group.

The number represented by the symbol m is 3, 4 or 5 or, preferably, 3 or 5 so that the methacryloxy-containing group bonded to the silicon atom of the inventive organosilane compound is a 3-methacryloxypropyl or 5-methacryloxypentyl group. The number n is zero, 1 or 2 or, preferably, zeor or 1.

Thus, several of the examples of the inventive organosilane compounds of the general formula (1) in conformity with the above described preferred definitions of the individual symbols are shown by the following structural formulas (A) to (I), in which Me, Et and Ph denote a methyl, ethyl and phenyl group, respectively. ##STR4##

The organosilane compound of the invention can be readily synthesized by the addition reaction between a corresponding alkenyl methacrylate represented by the general formula ##STR5## where m has the same meaning as defined above, and an alkenyloxysilane having a hydrogen atom directly bonded to the silicon atom represented by the general formula ##STR6## where R.sup.1, R.sup.2, R.sup.3, R.sup.4 and n each have the same meaning as defined above. For example, the compounds of the above given structural formulas (A) and (B) are obtained by the addition reaction between allyl methacrylate and methyl di(isopropenyloxy) silane or tri(isopropenyloxy)silane, respectively. The addition reaction is accelerated by the catalytic action of a metal belonging to the eighth group of the Periodic Table, e.g. platinum, or a compound containing the same metallic element. By the way, the above mentioned alkenyloxysilane having a silicon-bonded hydrogen atom is obtained by the dehydrohalogenation reaction between a halogenohydrogensilane and an aldehyde compound or ketone compound which is subject to keto-enol tautomerism in the presence of an acceptor for the hydrogen halide.

The methacryloxy- and alkenyloxy-containing silane compound of the invention is a carbon-functional silane of the de-ketonation type and exhibits excellent coupling effect for improving the adhesive bonding strength between inorganic and organic materials so that the inventive silane compounds are useful for improving the mechanical and electric properties of so-called FRP composite materials based on a synthetic resin having double bonds in the molecule since the inventive compound has a methacryloxy group in the molecule.

Following are the examples to illustrate the synthetic preparation and the properties of the organosilane compounds of the invention.

Into a reaction vessel were introduced 50.5 g (0.40 mole) of allyl methacrylate, 60 g of toluene, 0.05 g of an isopropyl alcohol solution of chloroplatinic acid containing 2.0% by weight of platinum and 0.05 g of methoxyhydroquinone and then 60.2 g (0.38 mole) of methyl di(isopropenyloxy)silane were added dropwise into the reaction mixture kept at 60.degree. C. with heating over a period of about 30 minutes. After completion of the addition of the silane compound, the reaction mixture was heated at 80.degree. C. for additional two hours to effect the addition reaction.

The reaction mixture was subjected to distillation under reduced pressure to give 82 g of a fraction boiling at 113.degree. C. under a pressure of 4 mmHg. This liquid product was identified to be 3-methacryloxypropyl methyl di(isopropenyloxy)silane from the results of analyses given below together with the value of the refractive index.

Molecular weight by mass spectrometry:

Refractive index n.sub.D.sup.25 : 1.4519. Infrared absorption spectral analysis: see FIG. 1.

The reaction was carried out in the same manner as in Example 1 except that 60.2 g of methyl di(isopropenyloxy)silane were replaced with 65.4 g (0.38 mole) of tri(isopropenyloxy)silane. Distillation of the reaction mixture after completion of the reaction under reduced pressure gave 69.5 g of a fracfraction boiling at 129.degree. to 132.degree. C. under a pressure of 3 mmHg. This liquid product was identified to be 3-methacryloxypropyl tri(isopropenyloxy)silane from the results of the analyses shown below. The above given yield of the product was about 56% of the theoretical value based on the starting silane compound.

Molecular weight by mass spectrometry:

Refractive index n.sub.D.sup.25 : 1.4522. Infrared absorption spectral analysis: see FIG. 2.

The experimental procedure was almost identical with that in Example 1 except that the methyl di(isopropenyloxy)silane was replaced with equimolar amount of an alkenyloxysilane expressed by the structural formula ##STR7##

The reaction product obtained by distillation under reduced pressure had a boiling point of 134.degree. C. under 1 mmHg and a refractive index n.sub.D.sup.25 of 1.4589 and was identified from the results of analyses to be the organosilane compound expressed by the structural formula (C) given above. The yield of the product was about 63% of the theoretical value based on the starting silane compound.

The experimental procedure was almost identical with that in Example 1 except that the methyl di(isopropenyloxy)silane was replaced with equimolar amount of an alkenyloxysilane expressed by the structural formula ##STR8##

The reaction product obtained by distillation under reduced pressure had a boiling point of 140.degree. C. under 3 mmHg and a refractive index n.sub.D.sup.25 of 1.4540 and was identified from the results of analyses to be the organosilane compound expressed by the structural formula (D) given above. The yield of the product was about 72% of the theoretical value based on the starting silane compound.