Silazane-siloxane random copolymers, their production and use

Abstract

The present invention relates to silazane-siloxane random copolymers as well as their production and their uses, particularly in LEDs.

Claims

1. A method for producing an electronic device, comprising: obtaining a silazane-siloxane random copolymer by reacting an organosilane, an amine and an organosiloxane, wherein the organosilane comprises two halogen end groups and the organosiloxane is of formula (II-a)
X.sup.3[SiR.sup.3R.sup.4O].sub.aSiR.sup.3R.sup.4X.sup.4(II-a) and the amine is of formula (III)
NH.sub.2R.sup.5(III) wherein X.sup.3 and X.sup.4 are at each occurrence independently selected from the group consisting of OH, Cl, Br, I; R.sup.3, R.sup.4 and R.sup.5 are at each occurrence independently H or a carbyl group; and a is an integer of at least 1 and at most 10; and providing a composition comprising the so-obtained silazane-siloxane random copolymer and applying the composition to a substrate of an electronic device.

2. Method according to claim 1, wherein the organosilane is of formula (I-a)
X.sup.1SiR.sup.1R.sup.2X.sup.2(I-a) wherein R.sup.1 and R.sup.2 are at each occurrence independently H or carbyl; and X.sub.1 and X.sup.2 are at each occurrence independently selected from the group consisting of Cl, Br, I.

3. Method according to claim 1, wherein the electronic device is an LED chip and the silazane-siloxane random copolymer is deposited directly onto the LED chip.

4. Method according to claim 1, wherein said composition further comprises a light emitting material.

5. Method according to claim 4, wherein the light emitting material is a phosphor.

6. A method for producing an electronic device, comprising: (a) obtaining a silazane-siloxane random copolymer by reacting an organosilane, ammonia or an amine and an organosiloxane, (b) providing a composition comprising the so-obtained silazane-siloxane random copolymer, and (c) subsequently depositing said composition on a substrate of an electronic device.

7. Method according to claim 6, wherein the silazane-siloxane random copolymer comprises a first monomer unit M.sup.l and a second monomer unit M.sup.2 in random sequence, wherein the first monomer unit M.sup.1 is of formula (I) and the second monomer unit M.sup.2 is of formula (II)
[SiR.sup.1R.sup.2NR.sup.5](I)
[SiR.sup.3R.sup.4[OSiR.sup.3R.sup.4].sub.aNR.sup.5](II) wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 are at each occurrence independently of each other selected from the group consisting of H and carbyl; and a is an integer of at least 1 and at most 10.

8. Method according to claim 7, wherein R.sup.1 and R.sup.2 are at each occurrence independently H or alkyl having at least 1 and at most 20 carbon atoms or phenyl.

9. Method according to claim 7, wherein R.sup.1 and R.sup.2 are independently H or methyl.

10. Method according to claim 7, wherein R.sup.3 and R.sup.4 are at each occurrence independently H or alkyl having at least 1 and at most 40 carbon atoms or phenyl.

11. Method according to claim 7, wherein R.sup.3 and R.sup.4 are independently methyl or phenyl.

12. Method according to claim 7, wherein R.sup.5 is at each occurrence independently H or alkyl having at least 1 and at most 20 carbon atoms or phenyl.

13. Method according to claim 7, wherein R.sup.5 is at each occurrence independently H or methyl.

14. Method according to claim 6, wherein the electronic device is an LED chip and the silazane-siloxane random copolymer is deposited directly onto the LED chip.

15. Method according to claim 6, wherein said composition further comprises a light emitting material.

16. Method according to claim 15, wherein the light emitting material is a phosphor.

17. Method according to claim 7, wherein: R.sup.1 and R.sup.2 are at each occurrence independently H or alkyl having at least 1 and at most 20 carbon atoms or phenyl; R.sup.3 and R.sup.4 are at each occurrence independently H or alkyl having at least 1 and at most 40 carbon atoms or phenyl; and R.sup.5 is at each occurrence independently H or alkyl having at least 1 and at most 20 carbon atoms or phenyl.

Description

EXAMPLES

(1) The following examples are intended to illustrate the advantages of the present invention in an exemplary and non-limiting way.

(2) Starting materials were obtained from commercial sources, for example dichlorosilane from Gelest Inc. USA, dichloromethylsilane and dichloro-dimethylsilane from Sigma-Aldrich, and the a,w-dichloro-dimethylsilicones from ABCR.

(3) Alternatively, ,-dichloro-dimethylsilicones may be prepared by reacting water with an excess of dichlorodimethylsilane in an inert solvent, such as for example tetrahydrofuran or 1,4-dioxane. Using the dichlorodimethylsilane in an excess will lead to incomplete hydrolysis and therefore to SiCl groups remaining. Solvent and unreacted dichlorodimethylsilane may be removed by distillation under reduced pressure to yield a colorless oil, which may be used without further purification or may further be purified by column chromatography or other methods.

Example 1

(4) A 4 l pressure vessel was charged with 1500 g of liquid ammonia at 0 C. and a pressure of between 3 bar and 5 bar. A mixture of 359 g dichlorosilane and 442 g 1,3-dichloro-tetramethyldisiloxane was slowly added over a period of 3 h. After stirring the resulting reaction mixture for an additional 3 h the stirrer was stopped and the lower phase isolated and evaporated to remove dissolved ammonia. After filtration 409 g of a colorless viscous oil remained.

Example 2

(5) A 4 l pressure vessel was charged with 1500 g of liquid ammonia at 0 C. and a pressure of between 3 bar and 5 bar. A mixture of 168 g dichlorosilane, 231 g dichloro-methylsilane and 419 g 1,3-dichloro-tetramethyldisiloxane were slowly added over a period of 3 h. After stirring the resulting reaction mixture for an additional 3 h the stirrer was stopped and the lower phase was isolated and evaporated to remove dissolved ammonia. After filtration 422 g of a colorless viscous oil remained.

Example 3

(6) A 4 l pressure vessel was charged with 1500 g of liquid ammonia at 0 C. and a pressure of between 3 bar and 5 bar. A mixture of 168 g dichlorosilane, 237 g dichloromethylsilane and 556 g 1,5-dichloro-hexamethyltrisiloxane were slowly added over a period of 3 h. After stirring the resulting reaction mixture for an additional 3 h the stirrer was stopped and the lower phase was isolated and evaporated to remove dissolved ammonia. After filtration 545 g of a colorless viscous oil remained.

Example 4

(7) A 4 l pressure vessel was charged with 1500 g of liquid ammonia at 0 C. and a pressure of between 3 bar and 5 bar. A mixture of 442 g dichloromethylsilane and 384 g 1,3-dichlorotetramethyldisiloxane were slowly added over a period of 3 h. After stirring the resulting reaction mixture for an additional 3 h the stirrer was stopped and the lower phase was isolated and evaporated to remove dissolved ammonia. After filtration 429 g of a colorless viscous oil remained.

Example 5

(8) A 4 l pressure vessel was charged with 1500 g of liquid ammonia at 0 C. and a pressure of between 3 bar and 5 bar. A mixture of 244 g dichloromethylsilane, 266 g dichlorodimethylsilane and 429 g 1,5-dichlorohexamethyltrisiloxane were slowly added over a period of 3 h. After stirring the resulting reaction mixture for an additional 3 h the stirrer was stopped and the lower phase was isolated and evaporated to remove dissolved ammonia. After filtration 526 g of a colorless viscous oil remained.

Example 6

(9) A 4 l pressure vessel was charged with 1500 g of liquid ammonia at 0 C. and a pressure of between 3 bar and 5 bar. A mixture of 503 g dichloromethylsilane and 645 g 1,7-dichlorooctamethyltetrasiloxane were slowly added over a period of 3 h. After stirring the resulting reaction mixture for an additional 3 h the stirrer was stopped and the lower phase was isolated and evaporated to remove dissolved ammonia. After filtration 703 g of a colorless viscous oil remained.

Example 7

(10) A 2 l flask was charged with a mixture of mixture of 44 g dichloromethylsilane, 56 g 1,3-dichlorotetramethyldisiloxane and 1500 ml n-heptane. The reaction solution was cooled to 0 C. and over a period of 2 h gaseous ammonia was bubbled below the surface of the solution, until no further salt formation was observed. After raising the temperature to room temperature, the precipitated ammonium chloride was removed by filtration, and the resulting colorless and transparent solution was reduced to dryness at a temperature of 50 C. under a vacuum of 40 mbar or less. 51 g of a colorless low viscous oil remained.

Example 8

(11) A 2 l flask was charged with a mixture of mixture of 44 g dichloromethylsilane, 56 g 1,3-dichlorotetramethyldisiloxane and 1500 ml n-heptane. The reaction solution was cooled to 0 C. and over a period of 2 h gaseous methylamine was bubbled below the surface of the solution, until no further salt formation was observed. After raising the temperature to room temperature, the precipitated methylammonium chloride was removed by filtration, and the resulting colorless and transparent solution was reduced to dryness at a temperature of 50 C. under a vacuum of 40 mbar or less. 56 g of a colorless low viscous oil remained.

Example 9

(12) A 2 l flask was charged with a mixture of mixture of 41 g dichloromethylsilane, 59 g 1,7-dichlorooctamethyltetrasiloxane and 1500 ml n-heptane. The reaction solution was cooled to 0 C. and over a period of 2 h gaseous ammonia was bubbled below the surface of the solution, until no further salt formation was observed. After raising the temperature to room temperature, the precipitated ammonium chloride was removed by filtration, and the resulting colorless and transparent solution was reduced to dryness at a temperature of 50 C. under a vacuum of 40 mbar or less. 39 g of a colorless low viscous oil remained.

Example 10 Fluoride-Catalyzed Crosslinking

(13) 100 g of the polymer of Example 4 were dissolved in 100 g 1,4-dioxane and cooled to 0 C. 100 mg tetramethylammonium fluoride were added, and the resulting reaction mixture was stirred for 4h, until gas formation stopped. 250 g xylene were added and the temperature was raised to room temperature. The turbid solution was filtrated, and the resulting clear solution was reduced to dryness at a temperature of 50 C. under a vacuum of 20 mbar or less. 95 g of a colorless highly viscous oil remained. The respective molecular weights of the polymer of Example 4 and the crosslinked polymer are indicated in Table 1.

Example 11 Base-Catalyzed Crosslinking

(14) 100 g of the polymer of Example 4 were dissolved in 100 g 1,4-dioxane and cooled to 0 C. 100 mg KH were added and the reaction solution was stirred for 4h, until gas formation stopped. 300 mg chlorotrimethylsilane and 250 g xylene were added and the temperature was raised to room temperature. The turbid solution was filtrated and the resulting clear solution was reduced to dryness at a temperature of 50 C. under a vacuum of 20 mbar or less. 95 g of a colorless highly viscous oil remained. The respective molecular weights of the polymer of Example 4 and the crosslinked polymer are indicated in Table 1.

(15) TABLE-US-00001 TABLE 1 M.sub.n Polymer [g mol.sup.-1] Example 4 3,100 Example 10 5,200 Example 11 4,750

Example 12

(16) To show its usefulness for LED devices, the polymer obtained in the examples were blended with phosphor light converter particles (available from Merck KGaA) in weight ratios ranging from 1:1 to 1:3, and the blend then coated as a 40 m to 80 m thick layer onto an LED chip mounted onto an LED package (available from Excelitas). For curing the polymer the LED was then placed on a hotplate at 150 C. for 8 hours.

(17) The finished LED was first operated for 24 hours at a starting current of 0.5 A. If no crack formation in the coating of the LED could be detected by microscope the current was raised in steps of 0.1 A, the LED operated for another 24 hours and inspected by microscope until the current for which crack formation could be observed. Because the LED current relates to the temperature of the chip this method gives an indication to the temperature resistance and the longevity of the so-produced LEDs. Table 2 shows the highest LED currents at which no crack formation had occurred for the LEDs produced with the polymers of the examples as well as for LEDs produced with phenylsilicone, Durazane 1033 and Durazane 1066 as reference materials. An example of a phenylsilicone is OE-6550, commercially available from Dow Corning, USA. Durazane 1033 and Durazane 1066 are organopolysilazanes, commercially available from Merck, Darmstadt, Germany.

(18) TABLE-US-00002 TABLE 2 Highest current without Polymer crack formation [A] Ex. 1 1.6 Ex. 2 1.7 Ex. 3 1.6 Ex. 4 1.6 Ex. 5 1.7 Ex. 6 1.6 Ex. 7 1.6 Ex. 8 1.7 Ex. 9 1.9 Ex. 10 1.9 Ex. 11 1.8 Phenylsilicone 1.5 Durazane 1033 1.0 Durazane 1066 1.1

(19) The present results clearly show that the present silazane-siloxane random copolymers are characterized by excellent temperature resistance and/or longevity when compared to conventional materials, such as for example to phenylsilicone or organopolysilazanes.