Abstract:
Heat-resistant silicone block polymer with a good flexibility obtained by reaction of an organosilsesquioxane with a silicone compound or organosiloxane in the presence of a basic catalyst in an organic solvent.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a heat-resistant silicone block polymer. 
     2. Description of the Prior Art 
     Heat-resistant silicone block polymers obtained from arylsilsesquioxane represented by the following general formula (1): ##STR1## wherein R&#39; is an aryl group and n is a positive integer of 25 to 500, and a silicone compound represented by the following general formula (2): ##STR2## wherein R&#34; is an alkyl group or an aryl group, Y is a halogen atom or a hydroxyl group, and m is a positive integer of 1 to 1,000 (U.S. Pat. No. 3,294,737) and those obtained from methylpolysiloxane having a number mean molecular weight of 9,000 to 10,000 represented by the following general formula (3): ##STR3## and a silicone compound represented by the following general formula (4): 
     
         XR&#34;&#39;.sub.2 Si(CH.sub.2).sub.l (R.sub.2 SiO).sub.m Si(CH.sub.2).sub.l SiR&#34;&#39;.sub.2 X                                             (4) 
    
     (Japanese Patent Application Kokai (Laid-open) No. 56-828) are well known. However, all of these silicone block polymers have a substantial flexibility but have a poor heat resistance. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide silicone block polymers having a substantial flexibility and an excellent heat resistance, and the object can be attained by converting a material having a substantial flexibility to that having a heat resistance. More particularly, the object can be attained by silicone block polymers obtained by reaction of organosilsesquioxane represented by the following general formula (5): ##STR4## wherein R 1  is a lower alkyl group having 1 to 5 carbon atoms, and/or an aryl group such as phenyl, tolyl, etc., and n is an integer of 0 to 4,000, with a silicone compound or organosiloxane represented by the following general formula (6) or (7) in an organic solvent in the presence of a basic catalyst: ##STR5## wherein R 2  is an arylene group such as ##STR6## etc. or a xylylene group such as ##STR7## etc., preferably a phenylene group, R 3  and R 4  are lower alkyl groups having 1 to 5 carbon atoms, alkenyl groups such as vinyl, allyl, methacroyl, etc. and/or aryl groups such as phenyl, tolyl, etc., preferably methyl groups or vinyl groups, X is a chlorine atom, a hydroxyl group, an alkoxy group such as methoxy, ethoxy, propoxy, etc., or an N,N-dialkylamino group such as N,N-dimethylamino, N,N-diethylamino, etc., preferably a chlorine atom or a hydroxyl group; and ##STR8## wherein R 2 , R 3 , R 4  and X have the same meanings as defined above, and p is an integer of 0-100, preferably an integer of 0-50. 
     The compound represented by the general formula (5) includes, for example, phenylsilsesquioxane, chlorophenylsilsesquioxane, diphenylsilsesquioxane, naphthylsilsesquioxane, tolylsilsesquioxane, cyanophenylsilsesquioxane, benzoylphenylsilsesquioxane, p-phenoxyphenylsilsesquioxane, methylsilsesquioxane, ethylsilsesquioxane, propylsilsesquioxane, tertbutylsilsesquioxane, etc., among which phenylsilsesquioxane and methylsilsesquioxane are preferable. The organosilsesquioxanes of the formula (5) have a number mean molecular weight of about 1,000 to about 600,000. 
     The compounds represented by the formulae (6) and (7) include, for example, bis(hydroxydimethylsilyl)benzene, bis(hydroxydiphenylsilyl)benzene, bis(hydroxydivinylsilyl)benzene, polytetramethyl-p-silphenylenesiloxane, polytetraphenyl-p-silphenylenesiloxane, polytetravinyl-p-silphenylenesiloxane, etc., among which polytetramethyl-p-silphenylenesiloxane and polytetraphenyl-p-silphenylenesiloxane are preferable. 
     The mixing ratio of the compound of the formula (5) to the compound of the formula (6) or (7) depends upon the species of the compounds, but is 100:5-400 by weight, preferably 100:20-200 by weight. Below 100:5, the flexibility is lost, whereas above 100:400, the heat resistance is lowered. 
     In the reaction of the compound of the formula (5) with the compound of the formula (6) or (7), a basic catalyst such as tert-amines, for example, pyridine, triethylamine, picoline, quinoline, N,N-dialkylaniline, etc. is used. When the compound of the formula (6) or (7) has a hydroxyl group as X, tetramethylammonium acetate, n-hexylamino-2-ethylhexoate, tetramethylguanidine-2-ethylhexoate, piperidine, triethanolamine, 1,4-diazobicyclo-[2,2,2]octane, etc. are used as the basic catalyst. 0.1-200 parts by weight of the basic catalyst is used per 100 parts by weight of the organosilsesquioxane of the formula (5). 
     The organic solvent for use in the reaction includes, for example, an aromatic hydrocarbon such as benzene, toluene, methoxybenzene, veratrole, diphenyl, diphenylether, etc.; a halogenated alkane such as dichloromethane, chloroform, etc., an ether such as diethylether, diisopropylether, tetrahydrofuran, etc.; a ketone such as acetone, methylisobutylketone, etc.; and a polar solvent such as N-methyl-2-pyrolidone, N-cyclohexyl-2-pyrolidone, etc.; preferably an aromatic hydrocarbon. 
     The reaction of the compound of the formula (5) with the compound of the formula (6) or (7) depends upon the boiling point of the organic solvent and the species of X in the compound of the formula (6) or (7), but can be carried out at 50°-200° C. for 5-50 hours. 
     The structure of the present heat-resistant silicone block polymer can be principally represented as follows: ##STR9## where (A) means an organosilsesquioxane unit, that is: ##STR10## and (B) means a tetraorganosilarylenesiloxane or tetraorganosilxylylenesiloxane unit, that is: ##STR11## wherein R 1  is a lower alkyl group having 1 to 5 carbon atoms, and/or an aryl group, R 2  is an arylene group, R 3  and R 4  are lower alkyl groups having 1 to 5 carbon atoms, alkylene group and/or aryl groups, n is an integer of 1 to 4,000, and p is an integer of 0 to 100. 
     The present heat-resistant silicone block polymer has a good adhesiveness to inorganic materials, for example, glass, silicon, metal such as aluminum, chromium, copper, etc., metal oxides, silicon nitride, etc., and also has a good heat-resistant property and a good mechanical strength, and thus can be used as an insulating film for solid elements in the semiconductor industry or as an interlayer insulating film for multi-layer wirings, or as an insulating film for print circuit boards. 
     In those applications, the present heat-resistant silicone block polymer is, for example, dissolved in an appropriate solvent, and the resulting solution is applied to a substrate of, for example, silicon, glass, etc. and then cured by heating, whereby an insulating film having a thickness of a few hundred to a few ten Å can be obtained. 
     In the curing by heating, a curing catalyst and an additive such as an adhesive promoter, etc. can be used, if desired. The curing catalyst can include, for example, silanol-based compounds and titanol-based compounds, and the adhesive promoter includes, for example, aminopropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, vinyltriethoxysilane, etc. besides the curing catalyst. If necessary, a substrate treated with a silanol-based compound such as polydihydroxysilane and polydialkoxysilane, a titanol-based compound such as polydialkoxytitanate and tetraalkoxytitanate, or an aluminum chelating compound such as aluminum monoethylacetate diisopropilate can be used to improve adhesion between the present heat-resistant silicone block polymer and the substrate. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention will be described in detail below, referring to Examples. 
     EXAMPLE 1 
     50 g (0.025 moles) of hydroxyl-terminated phenylsilsesquioxane (number mean molecular weight: 2,000), 40 g of benzene solution containing 1.5 g of tetramethylammonium acetate (0.3% by weight on the basis of the polymer), 200 g of diphenyl ether, 200 g of toluene, and 2.8 g (0.0125 moles) of p-bis(dimethylhydroxysilyl)benzene were charged into a 4-necked flask with a capacity of 500 ml, and dissolved with stirring. The resulting homogeneous solution was heated at 90° C. for 2 hours with stirring, and the resulting block polymer solution was poured into a mixed solvent of methanol-acetone (1:1 by volume) to precipitate polymer. The precipitates were recovered by filtration, washed with water and dried at 100° C., whereby the polymer having a number mean molecular weight of about 18,000 was obtained. The polymer had a heat resistance up to about 500° C. and the film prepared therefrom had a better flexibility than phenylsilsesquioxane. 
     EXAMPLE 2 
     55 g (0.011 mole) of hydroxyl-terminated phenylsilsesquioxane (number mean molecular weight: 5,000), 19.8 g (0.11 mole) of compound having the following formula (number mean molecular weight: 1,800): ##STR12## 200 g of diphenylether, 100 g of toluene, and a toluene solution containing 0.5% by weight of tetramethylammonium acetate on the basis of the hydroxyl-terminated phenylsilsesquioxane were charged into a 4-necked flask with a capacity of 500 ml, and dissolved with stirring. The resulting homogenous solution was distilled by heating at 130° C. for 4 hours with stirring to remove toluene therefrom, and the resulting reaction product solution was poured into a mixed solvent of methanol-acetone (1:1 by volume) to precipitate polymer. The precipitates were recovered by filtration, washed with water and dried at 120° C. under a reduced pressure, whereby block polymer having a number mean molecular weight of about 42,000 was obtained. The polymer had a heat resistance up to about 480° C. and the film prepared therefrom had a good flexibility. 
     EXAMPLE 3 
     40 g (0.004 moles) of hydroxyl-terminated phenylsilsesquioxane (number mean molecular weight: 10,000), 8.89 g (0.0405 moles) of p-bis(diphenylhydroxysilyl)benzene, and 200 g of toluene solution containing 0.5% by weight of tetramethylguanidine-di-2-ethylhexoate on the basis of the polymer were charged into a 4-necked flask with a capacity of 500 ml, and dissolved with stirring. The resulting homogeneous reaction solution was heated at the reflux temperature (about 110° C.) for 8 hours. The resulting reaction product solution was poured into a mixed solvent of methanol-acetone (1:1 by volume) to precipitate polymer. The precipitates were recovered by filtration, washed with water and dried at 100° C. under a reduced pressure, whereby polymer having a number mean molecular weight of 83,000 was obtained. The polymer had a heat resistance up to 520° C. and the film prepared therefrom had a good flexibility. 
     EXAMPLES 4-11 
     In these Examples, reagents shown in Table were mixed and subjected to reaction in the same manner as in Example 1 under reaction conditions as shown in Table, and results are shown in Table. 
     COMPARATIVE EXAMPLE 
     50 g (0.025 moles) of hydroxyl-terminated phenylsilsesquioxane (number mean molecular weight: 2,000), 50 g of benzene solution containing 1.6 g of tetramethylammonium acetate (0.3% by weight on the basis of the polymer), 200 g of diphenylether and 200 g of toluene were admixed with 5 g of pyridine and then with 3 g of Cl[(CH 3 ) 2  SiO] 10  (CH 3 ) 2  SiCl and then the mixture was subjected to reaction at 50° C. for 15 hours. The reaction product solution was poured into a mixed solvent of methanol-acetone (1:1 by volume) to precipitate block polymer. The resulting polymer was washed with methanol and then with water, and then dried at 50° C. under a reduced pressure, whereby the block polymer having a number mean molecular weight of about 6,000 was obtained. The polymer had a heat resistance up to about 350° C., and the film prepared therefrom had a good flexibility. In other words, the product polymer had a lower heat resistance than the phenylsilsesquioxane as the raw material. 
     
                                           TABLE__________________________________________________________________________Polymer [I]      Compound or polymer [II]     Number                                   NumberEx.       mean                                     meanNo.   Compound     M.W. g Compound name or polymer structure                                              M.W. g__________________________________________________________________________4  Hydroxyl-      5,000          12            p-bis-(dimethylhydroxysilyl)benzene                                              --   48   terminated   polymethyl-   silsesquioxane5  Hydroxyl- terminated polymethyl- silsesquioxane     &#34;    12             ##STR13##                         2,000                                                   10  6   Hydroxyl-     &#34;    12            &#34;                                 10,000                                                   24   terminated   polymethyl-   silsesquioxane7  Hydroxyl-     &#34;    20            p-bis(diphenylhydroxysilyl)benzene                                              --    2   terminated   polymethyl-   silsesquioxane8  Hydroxyl-     30,000          15            &#34;                                 --   20   terminated   polyphenyl-   silsesquioxane  9   Hydroxyl- terminated polyphenyl- silsesquioxane     30,000          15             ##STR14##                         5,000                                                   50  10   Hydroxyl- terminated polyphenyl- silsesqioxane     &#34;    15             ##STR15##                        --   0.8  11   Hydroxyl- terminated polyphenyl- silsesquioxane     &#34;    15             ##STR16##                        --   1.2__________________________________________________________________________            Catalyst and solvent                               Reaction                                      Number                                           Heat            (% by weight based                       Solvent Temp.                                   Time                                      mean resistance                                                 Flexi-            on polymer)                       (g)     (°C.)                                   (hr)                                      M.W. (°C.)                                                 bility__________________________________________________________________________            Toluene solution                       Diphenylether                               130 8  46,000                                           Up to 520                                                 Good            of tetramethyl-                       110            guanidine-            diethylhexoate            (0.5)            Benzene solution of                       Toluene 100 5  61,000                                           Up to 500                                                 Good            tetramethylammonium                       300            acetate            (0.5)            Benzene solution of                       Toluene  95 2  43,000                                           Up to 450                                                 Good            tetramethylammonium                       300            acetate            (0.5)            Benzene solution of                       Diphenylether                               120 5  49,000                                           Up to 530                                                 Good            tetramethylammonium                       180            acetate            (0.5)            Benzene solution of                       Benzene  80 7  83,000                                           Up to 510                                                 Good            tetramethylammonium                       130            acetate            (0.5)            1,4-bisazabicyclo-                       Toluene 100 4  54,000                                           Up to 460                                                 Good            [2,2,2]octane                       500            (2.5)            1,4-bisazabicyclo-                       Toluene 100 4  71,000                                           Up to 490                                                 Good            [2,2,2]octane                       500            (2.5)            1,4-bisazabicyclo-                       Toluene 100 4  61,000                                           Up to 460                                                 Good            [2,2,2]octane                       500            (2.5)__________________________________________________________________________