Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acid esters
Reexamination Certificate
1997-09-09
2001-06-05
Le, H. Thi (Department: 1773)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acid esters
C428S402000, C560S189000
Reexamination Certificate
active
06242639
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a method for preparing neopentyl glycol hydroxypivalate granules, to the granules obtained and to the use of a granulating apparatus for preparing the granules.
BACKGROUND OF THE INVENTION
Neopentyl glycol hydroxypivalate (NHP) is used, inter alia, as a component of inside coatings of cans, in order to increase the impact strength of the inside coatings. Processing of NHP for subsequent use is usually carried out by an NTIP melt being ;applied to a cooling belt via a droplet former. Flat, flaky granules are formed in the process which tend to cake together when stored in packages and containers.
Said caking then impedes proportioning and removal of the granules from the packages and containers.
DE-A-35 22 359 discloses a process for the processing of crystalline, organic materials such as neopentyl glycol hydroxypivalate so as to result in a product which is more readily free-flowing. This involves a pulverulent material being compacted in a twin-shaft screw machine having corotating shafts or a molten material being crystallized and compacted, at bulk temperatures which are from about 1 to 20° C. below the melting point of the material used. The material is then expelled, through a heated perforated plate, into a zone having a lower pressure.
The perforated plate is heated to a temperature of from 1 to 30° C. above the melting point of the material, so that the individual crystals being passed past the wall of the perforated plate fuse to produce a film which, after it has solidified, forms a firm corset for the compacted crystalline material. In a downstream zone the extrudates are reduced in size and cooled. The flowability of the granules thus obtained is not adequate for all applications.
DE-C-32 09 747 discloses an apparatus for preparing granules from a melt, in which a two-phase mixture from a melt which contains crystal seeds is applied to a cooling belt by means of a rotor droplet former, hemispherical granules being obtained in the process.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a process for preparing NHP granules, which results in low-caking granules and which avoids the drawbacks of known processes.
This object is achieved according to the invention by a method for preparing neopentyl glycol hydroxypivalate granules by application of a neopentyl glycol hydroxypivalate melt onto a cooling area, preferably a cooling belt on which the melt solidifies, wherein the melt contains at least 3 wt % of neopentyl glycol hydroxypivalate crystals, based on the total amount of neopentyl glycol hydroxypiivalate.
Preferably the necpentyl glycol hydroxypivalate melt is applied to the cooling belt as a sheet-like layer and after solidification is subjected to size reduction to produce granules or the melt is applied dropwise.
The process according to the invention allows the preparation of NHP granules which exhibit no caking tendency in packages and containers, as the contact areas between individual granular, particles are small. The essentially spherical NHP granules in particular, which are obtained by dropwise application of the melt, are very low caking.
Prior to cooling, the melt preferably contains from 3 to 60 wt %, particularly preferably from 15 to 55 wt %, especially from 30 to 50 wt % NHP crystals, based on the total amount of NHP. The NHP crystals or NHP crystal nuclei may, in the process, be added to the melt as a solid. Advantageously they are generated in the NHP melt in a precrystallizer in which the melt is agitated mechanically and is cooled at the same time, the melt for this purpose preferably being cooled in a precooler to a temperature close to the melting point. For NHP this temperature is in the vicinity of 50° C. The throughput through the precooler and the precrystallizer can be adjusted so as to obtain the desired crystal content in the melt at the outlet of the precrystallizer. Preferably a portion of the melt leaving the precrystallizer is recycled into the precrystallizer, ie. fed back in between precooler and precrystallizer.
In so doing it is possible, by adjusting the return-flow ratio downstream of the precrystallizer and selecting a suitable throughput and temperature in the precrystal-lizer, to generate a desired proportion of crystals in the melt.
REFERENCES:
patent: 2881230 (1959-04-01), Buell
patent: 4665219 (1987-05-01), Merger et al.
patent: 4769200 (1988-09-01), Hupfer et al.
patent: 5380919 (1995-01-01), Merger et al.
patent: 5936115 (1999-08-01), Melder et al.
patent: 2183774 (1995-11-01), None
patent: 3209747 (1982-03-01), None
patent: 4445880 (1994-12-01), None
patent: 210415 (1987-02-01), None
Baumann Dieter
Eck Bernd
Maltry Bernhard
Weyer Hans-Jurgen
BASF - Aktiengesellschaft
Keil & Weinkauf
Le H. Thi
LandOfFree
Preparation of neopentyl glycol hydroxyprivalate granules does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Preparation of neopentyl glycol hydroxyprivalate granules, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Preparation of neopentyl glycol hydroxyprivalate granules will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2505982