Claims
- 1. Magnetizable microspheres, comprising a matrix based on at least one organopolysiloxane of the formula (I)
- R"R'RSiO(SiR.sub.2 O).sub.n (SiRR"O).sub.m SiRR'R" (I)
- wherein:
- the R radicals may be identical or different, and are selected from a C.sub.1 -C.sub.3 alkyl radical and a phenyl radical;
- the R' radicals may be identical or different and are selected from an OH group, a C.sub.1 -C.sub.3 alkyl radical and a phenyl radical;
- the R" radicals may be identical or different and are selected from a C.sub.1 -C.sub.4 alkyl radical, a phenyl radical, 3,3,3-trifluoropropyl, a vinyl radical and a radical --R" --'X wherein R"' is a divalent organic radical and X is selected from an epoxy, hydroxy, carboxy, aldehyde, ester, aceto-ester, mercapto, mercapto ester, mercaptoalkoxy, amino, alkylamino, dialkylamino, trialkylamino, quaternary ammonium, amino alcohol, amido, hydrazide, hydrazino, C1-C3 haloalkyl, cyano, cyanato, ##STR11## sulfate, sulfonyl and halobenzyl group, at least 50% of the R radical are methyl radicals;
- n and m are whole or fractional numbers having a value sufficient to provide a matrix having a viscosity ranging from 400,000 to 10,000,000 mPas at 25.degree. C., and, if at least one R" is selected from a vinyl radical or said --R" --'X radical, n and m have values sufficient to provide a ratio of the number of R" units selected from a vinyl radical or said --R" '--X radical per organopolysiloxane molecule ranging from 1:1 to 1,000:1;
- and, encapsulated in said matrix, magnetizable particles having a diameter less than 300 angstroms.
- 2. The magnetizable microspheres as claimed in claim 1, wherein the divalent radical R"' is selected from a C.sub.1 -C.sub.18 linear alkylene radical, a C.sub.1 -C.sub.18 branched alkylene radical and a polyoxyalkylene radical containing from 1 to 50 C.sub.1 -C.sub.3 oxyalkylene units.
- 3. The magnetizable microspheres as claimed in claim 2, wherein at least one of said C.sub.1 -C.sub.18 linear alkylene radical and said C.sub.1 -C.sub.18 branched alkylene radical is extended with groups selected from among 1 to 5 ethylenamine divalent groups, 1 to 50 C.sub.1 -C.sub.3 alkylene oxide divalent groups and a ##STR12## group.
- 4. The magnetizable microspheres as claimed in claim 1, wherein the magnetizable particles are selected from magnetite, maghemite, chromium dioxide, ferrites and alloys of cobalt, nickel, gadolinium and samarium-cobalt.
- 5. The magnetizable microsphere as claimed in claim 1, wherein said ferrites are selected from ferrites of manganese, nickel and manganese-zinc.
- 6. The magnetizable microspheres as claimed in claim 5, wherein said magnetizable particles are magnetite.
- 7. The magnetizable microspheres as claimed in claim 1, wherein the diameter of said microspheres ranges from 0.05 to 3.
- 8. The magnetizable microspheres as claimed in claim 1, wherein said microspheres contain from 0.5 to 50% by weight of magnetizable particles relative to the matrix.
- 9. An aqueous dispersion of the magnetizable microspheres of claim 1, comprising 10 to 70% magnetizable microspheres by
- 10. The microspheres of claim 1, wherein at least one R radical is a 3,3,3-trifluoropropyl radical.
- 11. The microspheres of claim 1, wherein at least one R' radical is a 3,3,3-trifluoropropyl radical.
- 12. The microspheres of claim 1, wherein at least one R" radical is a 3,3,3-trifluoropropyl radical.
Priority Claims (1)
Number |
Date |
Country |
Kind |
87 09918 |
Jul 1987 |
FRX |
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Parent Case Info
This application is a continuation of application Ser. No. 07/219,384, filed July 15, 1988 now abandoned.
US Referenced Citations (3)
Number |
Name |
Date |
Kind |
3652761 |
Weetall |
Mar 1972 |
|
4356098 |
Chagnon |
Oct 1982 |
|
4695392 |
Whitehead et al. |
Sep 1987 |
|
Non-Patent Literature Citations (1)
Entry |
Rhone-Poulenc Technical Bulletin, 3/3/87. |
Continuations (1)
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Number |
Date |
Country |
Parent |
219384 |
Jul 1988 |
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