One-component, solvent-free organosiloxane composition for application to printed circuit boards by means of a cross-cut nozzle

Abstract

One-component, solvent-free organosiloxane composition comprising a) a linear or branched polyorganosiloxane containing at least two alkenyl or alkynyl groups, as component A; b) a linear or branched polyorganosiloxane containing at least 3 Si—H groups, as component B; c) a hydrosilylation catalyst as component C; d) an alkynol of the general formula (I) ##STR00001## wherein R.sup.1, R.sup.2, R.sup.3 are selected independently of one another from H, C.sub.1-C.sub.6-alkyl and substituted or unsubstituted C.sub.3-C.sub.6-alkyl; or R.sup.1 is selected from H, C.sub.1-C.sub.6-alkyl and substituted or unsubstituted C.sub.3-C.sub.6-cycloalkyl, and R.sup.2, R.sup.3 are bonded together and form a 3- to 8-membered ring which can be substituted by one or more C.sub.1-C.sub.3-alkyl groups, as component D; and e) a fumed silica as component E.

Claims

1. One-component, solvent-free organosiloxane composition comprising a) from 10 to 98% by weight of at least one linear or branched polyorganosiloxane containing at least two alkenyl or alkynyl groups, as component A; b) from 0.1 to 30% by weight of at least one linear or branched polyorganosiloxane containing at least 3 Si—H groups, as component B; c) from 0.000001 to 1% by weight of at least one hydrosilylation catalyst as component C; d) from 0.00001 to 5% by weight of at least one alkynol of the general formula (I) ##STR00006## wherein R.sup.1, R.sup.2, R.sup.3 are selected independently of one another from H, C.sub.1-C.sub.6-alkyl and substituted or unsubstituted C.sub.3-C.sub.6-cycloalkyl; or R.sup.1is selected from H, C.sub.1-C.sub.6-alkyl and substituted or unsubstituted C.sub.3-C.sub.6-cycloalkyl, and R.sup.2, R.sup.3 are bonded together and form a 3- to 8-membered ring which can be substituted by one or more C.sub.1-C.sub.3-alkyl groups, as component D; e) from 0.1 to 5% by weight of at least one fumed silica as component E; f) from 0 to 89.799989% by weight of one or more polyorganosiloxanes containing two terminal Si—H groups or one terminal Si-H group and one terminal alkenyl group, as component F; g) from 0 to 20% by weight of one or more polyepoxyorganosiloxanes as component G; h) from 0 to 30% by weight of one or more acyclic or cyclic organosiloxanes other than component A, having from 1 to 5 Si atoms and containing at least two alkenyl groups, as component H; and i) from 0 to 10% by weight of one or more additives as component I; wherein the sum of components A to I is 100% by weight.

2. Organosiloxane composition according to claim 1, wherein the viscosity of the organosiloxane composition is not more than 120 mPa.Math.s at a shear rate of 1000 s.sup.−1 and at least 5000 mPa.Math.s at a shear rate of 0.01 s.sup.−1.

3. Organosiloxane composition according to claim 1, wherein the organosiloxane composition comprises from 0.0001 to 89.799989% by weight of component F.

4. Organosiloxane composition according to claim 1, wherein component F comprises a polyorganosiloxane of the general formula (II) ##STR00007## wherein R.sup.4 is selected independently from C.sub.1-C.sub.6-alkyl, R.sup.5 is selected from H and C.sub.2-C.sub.6-alkenyl, and m is a number from 2 to 400.

5. Organosiloxane composition according to claim 1, wherein the organosiloxane composition comprises from 0.0001 to 20% by weight of component G.

6. Organosiloxane composition according to claim 1, wherein component G comprises a polyepoxyorganosiloxane of the general formula (III) ##STR00008## wherein R.sup.6 are selected independently of one another from C.sub.1-C.sub.6-alkyl and substituted or unsubstituted C.sub.6-C.sub.12-aryl, R.sup.7 is selected from substituted or unsubstituted glycidyloxy-(C.sub.1-C.sub.6-alkyl) and substituted or unsubstituted glycidyloxy-(C.sub.6-C.sub.12-aryl); and p is a number from 2 to 2000.

7. Organosiloxane composition according to claim 1, wherein the organosiloxane composition comprises from 0.0001 to 30% by weight of component H.

8. Organosiloxane composition according to claim 1, wherein component H comprises one or more organosiloxanes selected from the group consisting of 1,2-divinyltetramethyldisiloxane and 1,2,3,4-tetramethyl-1,2,3,4-tetravinyldimethyltricyclosiloxane.

9. Method for applying an organosiloxane protective coating to an electrical or electronic component, comprising the steps a)providing an organosiloxane composition according to claim 1, b) applying the organosiloxane composition to the electrical or electronic component by means of a cross-cut nozzle, and c) heating the electrical or electronic component coated with the organosiloxane composition to a temperature of from 50 to 110° C., whereby the organosiloxane protective coating is formed on the electrical or electronic component by hydrosilylation reaction.

10. Method according to claim 9, wherein the organosiloxane composition is applied in such a manner that an organosiloxane protective coating having a layer thickness of from 0.1 to 250 μm forms.

11. Method according to claim 9, wherein the organosiloxane composition is applied in step b) to a printed circuit board.

12. A method of use of an organosiloxane composition according to claim 1 comprising the step of applying an organosiloxane composition to an electrical or electronic component by means of a cross-cut nozzle.

13. A method of use according to claim 12, wherein the electrical or electronic component is a printed circuit board.

14. Organosiloxane protective coating obtained by the method according to claim 9.

15. Organosiloxane protective coating according to claim 14, wherein the protective coating has a layer thickness of from 0.1 to 250 μm.

16. Electrical or electronic component having an applied organosiloxane protective coating according to claim 14.

17. Organosiloxane composition according to claim 2, wherein the organosiloxane composition comprises from 0.0001 to 89.799989% by weight of component F.

18. Method for applying an organosiloxane protective coating to an electrical or electronic component, comprising the steps a) providing an organosiloxane composition according to claim 2, b) applying the organosiloxane composition to the electrical or electronic component by means of a cross-cut nozzle, and c) heating the electrical or electronic component coated with the organosiloxane composition to a temperature of from 50 to 110° C., whereby the organosiloxane protective coating is formed on the electrical or electronic component by hydrosilylation reaction.

19. Method for applying an organosiloxane protective coating to an electrical or electronic component, comprising the steps a)providing an organosiloxane composition according to claim 3, b) applying the organosiloxane composition to the electrical or electronic component by means of a cross-cut nozzle, and c) heating the electrical or electronic component coated with the organosiloxane composition to a temperature of from 50 to 110° C., whereby the organosiloxane protective coating is formed on the electrical or electronic component by hydrosilylation reaction.

20. Method for applying an organosiloxane protective coating to an electrical or electronic component, comprising the steps a)providing an organosiloxane composition according to claim 4, b) applying the organosiloxane composition to the electrical or electronic component by means of a cross-cut nozzle, and c) heating the electrical or electronic component coated with the organosiloxane composition to a temperature of from 50 to 110° C., whereby the organosiloxane protective coating is formed on the electrical or electronic component by hydrosilylation reaction.

21. Organosiloxane composition according to claim 1, wherein e) is from 0.1 to 4% by weight of at least one fumed silica as component E.

22. One-component, solvent-free organosiloxane composition comprising a) from 10 to 98% by weight of at least one linear or branched polyorganosiloxane containing at least two alkenyl or alkynyl groups, as component A; b) from 0.1 to 30% by weight of at least one linear or branched polyorganosiloxane containing at least 3 Si—H groups, as component B; c) from 0.000001 to 1% by weight of at least one hydrosilylation catalyst as component C; d) from 0.00001 to 5% by weight of at least one alkynol of the general formula (I) ##STR00009## wherein R.sup.1, R.sup.2, R.sup.3 are selected independently of one another from H, C.sub.1-C.sub.6-alkyl and substituted or unsubstituted C.sub.3-C.sub.6-cycloalkyl; or R.sup.1 is selected from H, C.sub.1-C.sub.6-alkyl and substituted or unsubstituted C.sub.3-C.sub.6-cycloalkyl, and R.sup.2, R.sup.3 are bonded together and form a 3- to 8-membered ring which can be substituted by one or more C.sub.1-C.sub.3-alkyl groups, as component D; e) from 0.1 to 10% by weight of at least one fumed silica as component E; f) from 0 to 89.799989% by weight of one or more polyorganosiloxanes containing two terminal Si—H groups or one terminal Si—H group and one terminal alkenyl group, as component F; g) from 0 to 20% by weight of one or more polyepoxyorganosiloxanes as component G; h) from 0 to 30% by weight of one or more acyclic or cyclic organosiloxanes other than component A, having from 1 to 5 Si atoms and containing at least two alkenyl groups, as component H; and i) from 0 to 10% by weight of one or more additives as component I; wherein the sum of components A to I is 100% by weight and wherein the organosiloxane composition comprises from 0.0001 to 20% by weight of component G.

23. One-component, solvent-free organosiloxane composition comprising a) from 10 to 98% by weight of at least one linear or branched polyorganosiloxane containing at least two alkenyl or alkynyl groups, as component A; b) from 0.1 to 30% by weight of at least one linear or branched polyorganosiloxane containing at least 3 Si-H groups, as component B; c) from 0.000001 to 1% by weight of at least one hydrosilylation catalyst as component C; d) from 0.00001 to 5% by weight of at least one alkynol of the general formula (I) ##STR00010## wherein R.sup.1, R.sup.2, R.sup.3 are selected independently of one another from H, C.sub.1-C.sub.6-alkyl and substituted or unsubstituted C.sub.3-C.sub.6-cycloalkyl; or R.sup.1is selected from H, C.sub.1-C.sub.6-alkyl and substituted or unsubstituted C.sub.3-C.sub.6-cycloalkyl, and R.sup.2, R.sup.3 are bonded together and form a 3- to 8-membered ring which can be substituted by one or more C.sub.1-C.sub.3-alkyl groups, as component D; e) from 0.1 to 10% by weight of at least one fumed silica as component E; f) from 0 to 89.799989% by weight of one or more polyorganosiloxanes containing two terminal Si—H groups or one terminal Si—H group and one terminal alkenyl group, as component F; g) from 0 to 20% by weight of one or more polyepoxyorganosiloxanes as component G; h) from 0 to 30% by weight of one or more acyclic or cyclic organosiloxanes other than component A, having from 1 to 5 Si atoms and containing at least two alkenyl groups, as component H; and i) from 0 to 10% by weight of one or more additives as component I; wherein the sum of components A to I is 100% by weight and wherein the organosiloxane composition comprises from 0.0001 to 30% by weight of component H.

Description

EXAMPLES

(1) The one-component, solvent-free organosiloxane compositions were applied using a coating machine from PVA, type PVA350, by means of a valve with a cross-cut nozzle of type XAE. The applications were carried out at room temperature and a nozzle pressure between 0.7 and 4.2 bar. The application rate was between 300 and 450 mm.Math.s.sup.−1.

(2) Measurements of the rheological parameters such as viscosity and shear rate were carried out using an MCR-302 from Anton Paar.

Example 1

(3) A base mixture of 300 parts by weight of a divinylpolydimethylsiloxane having a viscosity of 50 mPa.Math.s (component A), 30 parts by weight of a polydimethylsiloxane having an Si—H content of 7 mmol/g (component B), 5 parts by weight of 3,5-dimethyl-1-hexyn-3-ol (component D), 0.5 part by weight of a 1% solution of the Karstedt complex in 1,2-divinyltetramethyldisiloxane (component C), and 170 parts by weight of a linear polydimethylsiloxane having a terminal vinyl group and a terminal Si—H unit (component F) is mixed thoroughly. The viscosity of the mixture at 25° C. is 40 mPa.Math.s.

(4) To 96 parts by weight of that mixture there are then added 0.1 part by weight of a diepoxypolysiloxane having a viscosity of 10 mPa.Math.s (component G) and 3 parts by weight of a fumed silica partially coated with dimethylsilane (component E).

(5) The viscosity, measured at 25° C., is then 430,000 mPa.Math.s at a shear rate of 0.01 s.sup.−1 and 120 mPa.Math.s at a shear rate of 500 s.sup.−1.

(6) On application according to the above-described method, a uniform coating curtain was obtained and the coating no longer ran on the printed circuit board after application.

Example 2

(7) To 98 parts by weight of the base mixture from Example 1 there are added 0.1 part by weight of a diepoxypolysiloxane having a viscosity of 10 mPa.Math.s (component G) and 1 part by weight of a fumed silica partially coated with dimethylsilane (component E).

(8) The viscosity, measured at 25° C., is then 8000 mPa.Math.s at a shear rate of 0.01 s.sup.−1 and 120 mPa.Math.s at a shear rate of 11 s.sup.−1.

(9) On application according to the above-described method, a uniform coating curtain was obtained and the coating no longer ran on the printed circuit board after application.

Example 3

(10) To 97 parts by weight of the base mixture from Example 1 there are added 1 part by weight of a diepoxypolysiloxane having a viscosity of 10 mPa.Math.s (component G) and 2 parts by weight of an uncoated fumed silica (component E).

(11) The viscosity, measured at 25° C., is then 390,000 mPa.Math.s at a shear rate of 0.01 s.sup.−1 and 120 mPa.Math.s at a shear rate of 400 s.sup.−1.

(12) On application according to the above-described method, a uniform coating curtain was obtained and the coating no longer ran on the printed circuit board after application.

Example 4

(13) To a mixture of 46 parts by weight of a divinylpolydimethylsiloxane having a viscosity of 50 mPa.Math.s, 46 parts by weight of a divinylpolydimethylsiloxane having a viscosity of 100 mPa.Math.s (component A), 12 parts by weight of a polydimethylsiloxane having an Si—H content of 7 mmol/g (component B), 1 part by weight of 3-methylbut-1-yn-3-ol (component D), 0.2 part by weight of a 1% solution of the Karstedt complex in 1,2-divinyltetramethyldisiloxane (component C), and 68 parts by weight of a linear polydimethylsiloxane having a terminal vinyl group and a terminal Si—H unit (component F) there are added 3 parts by weight of a fumed silica partially coated with dimethylsilane (component E).

(14) The viscosity, measured at 25° C., is then 50,000 mPa.Math.s at a shear rate of 0.01 s.sup.−1 and 120 mPa.Math.s at a shear rate of 110 s.sup.−1.

(15) On application according to the above-described method, a uniform coating curtain was obtained and the coating no longer ran on the printed circuit board after application.

Comparative Example 1

(16) A coating consisting of 300 parts by weight of a divinylpolydimethylsiloxane having a viscosity of 50 mPa.Math.s (component A), 30 parts by weight of a polydimethylsiloxane having an Si—H content of 7 mmol/g (component B), 0.66 part by weight of a 20% solution of a triorganophosphite in xylene (component “δ”), 0.1 part by weight of a 1% solution of the Karstedt complex in 1,2-divinyltetramethyldisiloxane (component C) is mixed thoroughly.

(17) The mixture has a viscosity, measured at 25° C., of 3000 mPa.Math.s at a shear rate of 0.01 s.sup.−1 and 120 mPa.Math.s at a shear rate of 100 s.sup.−1.

(18) Coating with a cross-cut nozzle according to the above-described method is possible, but the coating spreads and runs extensively over the printed circuit board because the flow anomaly is much too small.

Comparative Example 2

(19) A coating consisting of the constituents of Comparative Example 1 but with an additional 3.5 parts by weight of a fumed silica partially coated with dimethylsilane (component E) in order to increase the flow anomaly has a viscosity, measured at 25° C., of 200,000 mPa.Math.s at a shear rate of 0.01 s.sup.−1 but also a viscosity of over 120 mPa.Math.s even at shear rates of >1000 s.sup.−1. For example, the viscosity is 195 mPa.Math.s at a shear rate of 1000 s.sup.−1. No coating curtain opens on passage through the cross-cut nozzle.