Production of nanoparticulate compressed tablets (pellets) from synthetic or natural materials using a specially developed grinding and compressing method

Abstract

A method for producing nanoparticulate compressed tablets/pellets from synthetic and/or natural materials, and compressed tablets/pellets produced using the method for producing nanoparticulate compressed tablets/pellets from synthetic and/or natural materials and to uses thereof.

Claims

1. A method for producing nanoparticulate compressed tablets/pellets from synthetic and/or natural materials comprising the steps of: producing a fine-ground powder (p) with grain size<75 μm, wet grinding (M) the fine-ground powder (p) in a grinding arrangement, jet-mill grinding arrangement and/or high-energy ball mill grinding arrangement to produce a ground material (p.sub.M) with a particle size in the range of 30-150 nm and with a D.sub.90<1 μm; transfering and drying, thermal drying or freeze-drying (G) the ground material (p.sub.M) to produce a dried nanopowder (p.sub.MG); re-homogenizing (R) the dried nanopowder (p.sub.MG) to produce a dried and re-homogenized nanopowder (p.sub.MGR), and pressing (P) at least an aliquot of dried and re-homogenized nanopowder (p.sub.MGR) into a tablet/pellet (t) in a high pressure press in the working range of 2 to 80 tons without addition of binder.

2. A method for producing nanoparticulate compressed tablets/pellets according to claim 1, wherein the pressing (P) in the high pressure press occurs with a polished sapphire, glass and/or diamond disk between a pressing tool and the aliquot of dried and re-homogenized nanopowder (p.sub.MGR) and wherein the pressing tool is shaped according to the area of application.

3. A method for producing nanoparticulate compressed tablets/pellets according to claim 1, wherein the wet grinding (M) is carried out with a liquid, wherein the liquid is water and/or an organic solvent.

4. A method for producing nanoparticulate compressed tablets/pellets according to claim 1, wherein the pressing (P) of the aliquot of dried and re-homogenized nanopowder (p.sub.MGR) takes place in a high pressure press in the working range of 3 to 40 tons.

5. A method for producing nanoparticulate compressed tablets/pellets according to claim 1, wherein the pressing (P) of the aliquot of dried and re-homogenized nanopowder (p.sub.MGR) takes place in a high pressure press in the working range of 5-20 tons.

6. Compressed tablets/pellets made by the method of claim 1.

7. A method for calibration of equipment for solid-state analysis, the method comprising first using a compressed tablet/pellet produced according to claim 1 as a reference material for the equipment for solid-state analysis or as a medium for direct solid-state analysis.

Description

(1) There is shown in:

(2) FIG. 1 a schematic representation of an embodiment of the manufacturing method known in the prior art and

(3) FIG. 2 a schematic representation of an embodiment of the manufacturing method disclosed herein.

(4) In FIG. 1 a schematic representation of an embodiment of the manufacturing method known in the prior art is shown.

(5) In this case, the starting material p is first of all finely ground (<75 μm) and subsequently mixed A(b) with a binder b, for example cellulose, wax, boric acid, organic compounds, etc. and homogenized H. Subsequently, an aliquot thereof (p+b).sub.H is pressed P in a high pressure hydraulic press at 5 to 20 t to form a tablet or pellet t(p+b).sub.H.

(6) FIG. 2 shows a schematic representation of an embodiment of the manufacturing method disclosed herein.

(7) In a first step, 3-4 g of finely ground powder p of the original material are weighed in a grinding cup, for example made of agate, under a so-called clean bench in a particle-free atmosphere.

(8) The grinding cup already contains a certain amount of grinding balls made of agate, whereby diameter and total mass of the balls depends on the material (grinding protocol).

(9) Grinding balls and cups had previously been cleaned by grinding of high purity (optical grade) quartz powder. There follows an addition of de-ionized water (DIW, >18.2 MOhm), wherein the amount depends on the material to be ground (grinding protocol) and is such that during grinding a suspension with oil-like viscosity is formed. Subsequently, the grinding cup is sealed and inserted in a ball grinder.

(10) This is followed by a wet grinding M in a high-energy ball grinder in interval operation.

(11) The grinding time is material-specific and has been optimized for a number of materials (grinding protocol). This produces particles with particle sizes in the nanometer range (30-150 nm, D.sub.90<1 μm).

(12) The ready-ground nanopowder p.sub.M is rinsed from the balls and the grinding bowl with DIW as a suspension and transferred with a pipette into a pre-cleaned plastic cup. The plastic cup with the suspension (about 50-100 ml) is snap frozen at −80° C. and then dried in a freeze dryer G over 72-96 h.

(13) The dried nanopowder p.sub.MG H is transferred into a hand-mortar made of agate and re-homogenized H.

(14) The re-homogenized nanopowder p.sub.MG H is weighed in the pressing tool (about 600 mg for a tablet of 13 mm diameter), then this is placed in a programmable hydraulic tablet press and then the powder is compressed P with 10 t/cm.sup.2 (for 13 mm diameter; press protocol) for 1 minute.

(15) In order to avoid contamination of the tablet surface by the metallic pressing punch and to achieve a very smooth and even surface, a sapphire disc is placed between powder p.sub.MG and punch. Depending on the analytical application, tablets t (p.sub.MGH with different diameters (e.g. 5, 10, 13, 32 mm) are produced.

LIST OF REFERENCE NUMBERS

(16) A addition of a binder b B binder G freeze drying H rehomogenizing M grinding process e.g. wet grinding P pressing P powder, analytically finely ground p.sub.M powder, ground p.sub.MG nanopowder e.g. powder, ground and freeze-dried p.sub.MGH homogenized nanopowder e.g. powder, ground, freeze-dried and re-homogenized p+b powder with binder (p+b).sub.H powder with binder, homogenized t pellet, tablet