PROCESS FOR THE MANUFACTURE OF FLUX COMPOSITIONS

Abstract

The present invention concerns a process for the manufacture of flux compositions, flux compositions obtainable by the process according to the invention, aluminum or aluminum alloy parts at least partially coated with the flux composition manufactured by the process, and a brazing process and brazed metal object obtainable by said process.

Claims

1. A process for the manufacture of a flux composition, comprising at least one binder, at least one dispersion agent and at least one flux, the process comprising maintaining a temperature of equal to or lower than 70 C. during and after addition of the binder.

2. The process for the manufacture of a flux composition according to claim 1, comprising a) Mixing at least one flux and at least one dispersion agent b) Homogenizing the mixture obtained by step a) c) Controlling the temperature of the mixture obtained by step b) such that a temperature of equal to or lower than 70 C., is achieved and maintained d) Adding at least one binder to the mixture obtained by the foregoing steps at a temperature of equal to or lower than 70 C.

3. The process for the manufacture of a flux composition according to claim 1, comprising a. Mixing at least one binder and at least one dispersion agent, wherein a temperature of equal to or lower than 70 C. is maintained during the mixing, b. Optionally homogenizing the mixture obtained by step a. while controlling the temperature of the mixture such that a temperature of equal to or lower than 70 C. is maintained c. Adding at least one flux to the mixture obtained by the one or more foregoing steps at a temperature of equal to or lower than 70 C. d. Homogenizing the mixture obtained by step c) while controlling the temperature of the mixture such that a temperature of equal to or lower than 70 C. is maintained.

4. The process according to claim 1, wherein the at least one binder which is added is comprised in a binder composition.

5. The process according to claim 1, wherein the flux is a flux suitable for brazing of aluminum parts or aluminum alloy parts.

6. The process according to claim 1, wherein the at least one binder is selected from the group consisting of butyl rubbers, polyurethanes, resins, phthalates, polyacrylates, polymethacrylates, vinyl resins, epoxy resins, nitrocellulose, polyvinyl acetates, polysaccharide acetates, and polyvinyl alcohols.

7. The process according to claim 1, wherein the at least one dispersion agent is selected from the group consisting of water, alcohols, ketones, aliphatic hydrocarbons, ethers, and aromatic hydrocarbons.

8. The process according to claim 1, wherein the content of flux in the flux composition is equal to or greater than 0.75% by weight, and equal to or less than 45% by weight of the total weight of the flux composition.

9. The process according to claim 1, wherein the content of binder in the flux composition is equal to or greater than 0.1% by weight, and equal to or less than 40% by weight of the total weight of the flux composition.

10. The process according to claim 1, wherein in at least one of the steps wherein mixing is performed, a stirrer exerting shear force or a wet milling step is used for mixing.

11. A flux composition comprising a flux and a binder, obtained by the process according to claim 1.

12. A process for the manufacture of coated parts, the process comprising a) coating the parts at least partially with the flux composition according to claim 11; b) optionally drying the at least partially coated parts.

13. Coated metal parts at least partially coated with at least one flux composition according to claim 11.

14. A process for brazing coated metal parts according to claim 13, the process comprising c) assembling the at least partially coated parts; d) heating the assembled, at least partially coated parts to a temperature sufficiently high to braze the at least partially coated parts; e) brazing the at least partially coated parts; f) optionally cooling the brazed parts.

15. A brazed metal object, obtained according to the process according to claim 14.

16. The process according to claim 1, comprising maintaining a temperature of equal to or lower than 60 C. during and after addition of the binder.

17. The process according to claim 1, comprising maintaining a temperature of equal to or lower than 50 C. during and after addition of the binder.

18. The process according to claim 5, wherein the flux comprises at least one compound selected from the group consisting of potassium fluoroaluminate, cesium fluoroaluminate, potassium fluorozincate and potassium fluorosilicate.

19. The process according to claim 6, wherein the at least one binder is selected from the group consisting of polyurethanes.

20. The process according to claim 7, wherein the at least one dispersion agent is selected from the group consisting of polyhydric alcohols and water.

Description

EXAMPLE 1

[0065] 193.75 kg demineralized water are stirred by a pitch blade turbine and 150 kg of Nocolok (R) flux is added in three portions. The mixture is passed through a colloid ball mill and fed into a 700 L tank with a temperature controlled jacket. The mixture is adjusted to 28 C., and a binder composition containing 25 kg polyurethane binder and 131.25 kg demineralized water is added while the mixture is stirred using a pitch blade turbine. During and after addition, the temperature in the tank is controlled at 28 C. The mixture is filtered through a 300 mesh sieve.

EXAMPLE 2

[0066] 188.5 kg demineralized water are stirred with a pitch blade turbine and 147.75 kg of Nocolok (R) flux is added in three portions. The mixture is passed through a colloid ball mill and fed into a 700 L tank with a temperature controlled jacket. The mixture is adjusted to 28 C., and a binder composition containing 25 kg polyurethane binder and 131.25 kg demineralized water is added while the mixture is stirred using a pitch blade turbine. During and after addition, the temperature in the tank is controlled at 28 C. To the mixture, a mixture of 2.25 kg CsAlF4 and 5.25 kg demineralized water, which have been treated for 5 minutes with an ultra turrax and temperature-adjusted to 28 C., are added to the mixture in the tank. The mixture is homogenized using a pitch blade turbine at 28 C., and filtered through a 300 mesh sieve.

EXAMPLE 3

[0067] 322 kg demineralized water are stirred in a 700 l tank with a pitch blade turbine, and 150 kg Nocolok (R) are added in 3 portions. The mixture is homogenized with a rotator-stirrer-stirrer. The temperature is adjusted to 27 C., and, stirring with a pitch blade turbine, 27.7 kg of a binder composition (36.6 weight % polyester polyurethan, 62,7 weight % demineralized water, 0.5 weight % siloxane surfactant, 0.2 weight % defoamer on polysiloxane basis) are added, while a temperature of 27 C. is maintained.

EXAMPLE 4 (Comparative)

[0068] 322 kg demineralized water are stirred in a 700 l tank with a pitch blade turbine, and 150 kg Nocolok (R) are added in 3 portions. The mixture is homogenized with a rotator-stator-stirrer. The temperature reaches 55 C. 27.7 kg of a binder composition (36.6 weight % polyester polyurethan, 62,7 weight % demineralized water, 0.5 weight % siloxane surfactant, 0.2 weight % defoamer on polysiloxane basis) are added immediately while stirring with the rotator-stator-stirrer, and a temperature of 53 C. is observed.

Stability Observations:

[0069] The flux compositions of example 1-3 display very good stability, settling behaviour and homogeneity after storage for 48 hours at room temperature. The flux composition of example 4 displays a certain degree of phase separation, clogging and uneven thickness distribution (visual inspection, apparent partial gelling/polymerization) after storage for 48 hours at room temperature.

Application of Flux Composition to Aluminum Parts

[0070] The flux compositions of examples 1-3 display a good paintability (machine painting) on aluminum parts, also after 48 hours of storage. Flux composition of example 4 displays some clogging in the paint flux apparatus, and uneven paint flux distribution on the aluminum parts.