Method for producing powdered lauroyl peroxide

Abstract

The present application relates to a method for producing powdered lauroyl peroxide which is characterized in that a reaction mixture is used which comprises water, lauric acid chloride, hydrogen peroxide, an inorganic base and an alkane.

Claims

1. Method for producing powdered lauroyl peroxide having a particle size according to the d.sub.90 value of from 50 m to 400 m, wherein a reaction mixture is used which comprises water, lauric acid chloride, hydrogen peroxide, an inorganic base and an alkane, and the method is carried out at a predetermined temperature in the range of from approximately 10 C. to approximately 30 C., the lauroyl peroxide not being heated above the melting point thereof during the method.

2. Method according to claim 1, wherein production of lauroyl peroxide is carried out in the aqueous phase.

3. Method according to claim 1, wherein the method is carried out at a predetermined temperature in the range of from approximately 15 C. to approximately 20 C.

4. Method according to claim 1, wherein the alkane is selected from the group consisting of straight-chain alkanes, branched-chain alkanes, cyclic alkanes, and mixtures thereof.

5. Method according to claim 1, wherein the alkane is a C.sub.5-12-alkane.

6. Method according to claim 1, wherein an aqueous solution of sodium hydroxide, potassium hydroxide, or mixtures thereof, is used as the inorganic base.

7. Method according to claim 1, wherein a molar excess of hydrogen peroxide above a theoretically required amount in the reaction mixture is from approximately 30% to approximately 80%.

8. Method according to claim 1, wherein a mass ratio of alkane to lauric acid chloride in the reaction mixture is in the range of from approximately 1:10 to approximately 1:1.

9. Method according to claim 1, wherein the reaction mixture comprises further components selected from the group consisting of stabilisers for the hydrogen peroxide, surfactants, alcohols, and combinations thereof.

10. Method according to claim 9, wherein ethylenediaminetetraacetic acid or salts thereof are used as the stabilisers for the hydrogen peroxide.

11. Method according to claim 1, wherein the reaction is carried out in a stirred-tank reactor.

12. Method according to claim 1, wherein the method is carried out as a batch process.

13. Method according to claim 1, said method comprising the steps of: i) providing an aqueous solution comprising hydrogen peroxide and an inorganic base; ii) adding an alkane; iii) adding lauric acid chloride in a temperature-controlled manner while stirring; iv) continuing the stirring in a temperature-controlled manner; v) filtering the resulting precipitate; vi) washing the precipitate; and vii) optionally drying the precipitate.

14. Method according to claim 13, wherein during at least steps ii) to iv), a predetermined temperature in the range of from approximately 10 C. to approximately 30 C. is maintained by cooling.

15. Method according to claim 13, wherein the lauroyl peroxide is not heated above the melting point thereof during the method.

16. Powdered lauroyl peroxide formed using the method claim 1, wherein the lauroyl peroxide has a d.sub.90 value in the range of from 50 m to 400 m.

17. Powdered lauroyl peroxide according to claim 16, wherein the lauroyl peroxide has a d.sub.50 value in the range of from 10 m to 300 m.

18. Method according to claim 5, wherein the alkane is isohexane.

19. Method according to claim 7, wherein the molar excess of hydrogen peroxide above the theoretically required amount in the reaction mixture is from approximately 50% to approximately 60%.

20. Method according to claim 8, wherein the mass ratio of alkane to lauric acid chloride in the reaction mixture is approximately 1:4.

Description

FIGURES

(1) FIG. 1 shows the particle size distribution of lauroyl peroxide produced according to the invention,

(2) FIG. 2 shows the particle size distribution of lauroyl peroxide produced according to the prior art.

EXAMPLES

Example 1: Production of Powdered Lauroyl Peroxide

(3) 1250 g water, 42 g (0.86 mol) hydrogen peroxide 70%, 252 g (1.58 mol) caustic soda lye 25% and 60 g isohexane are provided and cooled to 16 C. 240 g (1.10 mol) lauric acid chloride are added dropwise, over 20 minutes while cooling, at temperatures of from 16 to 18 C. Following the addition, the reaction mixture is stirred for a further 20 minutes at the same temperature. Said mixture is filtered using a Nutsche filter and the solid matter obtained is repeatedly washed using a total of 4 liters of water. 291 g of product damp from water is obtained having a content of 75%, which corresponds to a yield of 98%. After drying in air or in a vacuum, the lauroyl peroxide content was 99.1%. The chlorine content in the product is 60 ppm, the lauric per-acid content is 0.01%.

(4) The particle size distribution is very homogeneous without any further pulverisation and has a d.sub.50 value of 153 m and a d.sub.90 value of 222 m. The spread is shown in FIG. 1. A spread of a commercially available lauroyl peroxide powder has been recorded for the purpose of comparison (FIG. 2). Said powder has a d.sub.50 value of 360 m and a d.sub.90 value of 856 m.

Example 2: Use of Lauroyl Peroxide in Resin Curing

(5) Lauroyl peroxide (LP) is used not only in PVC production, but also in resin curing for example. For this purpose, said lauroyl peroxide has to first be dissolved in the polystyrene resin. Comparative dissolution trials were carried out for commercially available LP flakes and LP powder according to the invention. In the process it was found that, as expected, the LP powder dissolved more quickly than the flakes.

(6) TABLE-US-00001 TABLE 1 Dissolution speed of LP in 20 g styrene, while stirring Amount in g Dissolution time in min LP flakes 9.5 8 Dry LP 9.5 6 LP-75-W * 11.0 6 * powder, damp from water, having 75% LP content not according to the invention

(7) During a curing trial, the gel time t.sub.gel, the maximum temperature T.sub.max reached in the process, and the time t.sub.max until this maximum temperature was reached, were determined:

(8) Curing: in accordance with DIN 16945 in a test tube at 80 C.

(9) Resin: Palatal P4

(10) Filler: aluminium trihydroxide (40 parts to 100 parts resin)

(11) TABLE-US-00002 Peroxide amount t.sub.gel in min t.sub.max in min T.sub.max in C. LP flakes 1.0% 27.9 31.6 155 Dry LP 1.0% 24.9 27.8 163 LP-75-W 1.3% 25.5 28.2 165 not according to the invention

(12) It can be seen that the times t.sub.gel and t.sub.max are shorter and T.sub.max is longer. Accordingly, the LP powder is more active than the LP flakes.