The stage division of silver powder used for solar batteries
The present invention relates to the classification technique field of metal-powder, be specifically related to a kind of stage division of silver powder used for solar batteries.
Silver powder is most widely used a kind of noble metal powder maximum with consumption in electronics industry, be the functional material of the most fundamental sum key of production electronic component products, and the classification process of silver powder is the committed step realizing its extensive use.
At present, silver powder preparation method both domestic and external has: thermal decomposition method, electrochemical process, chemical reduction-deposition and physical vaporous deposition.
PVD(physical vapour deposition (PVD)) method adopts physical method to prepare a kind of method of metal nano powder.The methods such as the preparation of nano-silver powder also adopts this kind of method, utilizes vacuum evaporation, heating high-frequency induction realize.Its principle first silver atoms vaporization is formed plasma, then quenching, finally forms the superfine powder of good dispersion, uses that the metal nano powder purity prepared of the method is high, better crystallinity degree, size tunable.
But, use the metal nano aluminium powder broad particle distribution of PVD method production (from PSD and particle size distribution data, its curve is low and slow parabolic curve), bulky grain is many, and solar energy industry development is more and more meticulousr, also more and more higher to the requirement of powder, requirement powder granule is even, be convenient to printing, therefore must carry out certain classification process for powder, just can reach the instructions for use of solar cell.Existing what adopt for sub-micron-sized metal powder in the industry is substantially all gas phase or liquid phase classification, and its operation principle relies on the centrifugal force in conical vessel to be separated from the different holes of cyclone by the particle of different-grain diameter size.Namely realize as separating medium with gas or liquid respectively.Separation of Solid and Liquid is carried out in liquid phase classification generally simple employing water or organic solvent, when doing classification medium with organic solvent, the dispersed instructions for use that can reach electronic devices and components, but output is lower, organic solvent belongs to inflammable and explosive product mostly simultaneously, in normal production process, easy initiation potential, causes production accident, and production cost is higher simultaneously; If only use deionized water to do classification medium, the dispersed instructions for use not reaching again powder simultaneously.
Summary of the invention
When the present invention is directed to prior art deficiency, provide one to ensure classification efficiency, powder dispersity can be made again to reach the stage division of the silver powder used for solar batteries of the instructions for use of solar cell.
In order to solve the problems of the technologies described above, the technical solution used in the present invention is: a kind of stage division of silver powder used for solar batteries, and the step of the method is as follows:
(1) dispersant is joined in deionized water, be mixed with dispersant (mass fraction of the dispersant) aqueous solution that mass fraction is 0.1% ~ 2%, with average grain diameter at the silver powder of 200 ~ 1000nm for raw material, joined in this solution, be mixed into solid-liquid system, the solid content of this solid-liquid system controls 1% ~ 30%;
(2) the solid-liquid system of step (1) is carried out mechanical dispersion process, dispersion treatment time 20 ~ 60min, during dispersion treatment, solid-liquid system temperature controls, at 10 DEG C ~ 50 DEG C, to obtain finely dispersed slip;
(3) step (2) finely dispersed slip is passed through 40 ~ 600 eye mesh screens, the slip by screen cloth is collected;
(4) be transported in hydrocyclone by the slip booster pump that step (3) is collected, booster pump outlet pressure controls at 0.2 ~ 1.6MPa, and the inlet flow rate of cyclone controls at 5 ~ 30m
3/ h, the overflow outlet flow-control of hydrocyclone is at 0.3 ~ 3m
(5) by hydroclone classification time controling at 1h ~ 1.5h, cyclone overflow outlet slip is collected, obtains quality good, the silver powder of be evenly distributed (from ESEM, powder is approximate, adjoining dimensions).
The present invention's former powder silver powder used is the standby nano-silver powder of PVD legal system.
Silver powder preferable particle size scope described in step of the present invention (1) is the metal nano silver powder of 400 ~ 700nm.
Dispersant described in step of the present invention (1) is the one in ammonium polyacrylate, lauryl sodium sulfate or methyl anyl alcohol.
Solid content optimized scope described in step of the present invention (1) is 5% ~ 25%.
Its dispersal device adopted of mechanical dispersion described in step of the present invention (2) be high speed disintegrator dispersion, ultrasonic agitation dispersion, mulser as the one in triode line formula mulser, be industry conventional disperse equipment, process for dispersing is also conventional method.
Described in step of the present invention (2), temperature controls below 35 DEG C.
Booster pump described in step of the present invention (4) is the one in centrifugal pump of horizontal axis, vertical centrifugal pump, vertical multi-stage centrifugal pump or screw pump, is industry conventional equipment.
Powder described in step of the present invention (5) is collected and is adopted collected by centrifugation, and industry conventional centrifuge can realize.
The benefit of advantage of the present invention and generation:
1. the present invention uses the deionized water solution adding dispersant as classification medium, respectively with do not add the deionized water of dispersant, alcohol does classification medium and contrasts, metal nano silver powder disperses better in the deionized water adding dispersant, by controlling the solid content of solid-liquid system, the utilization of cyclone maximal efficiency can be made, make grading effect reach best;
2. the present invention uses the deionized water solution adding dispersant as classification medium, do medium carry out classification than only using deionized water, and not only output increased is a lot, and dispersiveness is also better, does not also have bubble to produce in process of production simultaneously; And with alcohol carry out doing contrast when, classification output, than height when using alcohol, also improves the security of production process simultaneously, has saved cost.
Detailed description of the invention
Below by embodiment, the present invention is described in further detail, the present invention is not only confined to following examples.
The equipment that the present embodiment adopts is industry conventional equipment.
(1) with the raw material of the average grain diameter that PVD legal system the is standby nano-silver powder that is 620nm as classification, joined in the deionized water solution (in the deionized water solution of ammonium polyacrylate, the mass concentration of ammonium polyacrylate is 1%) adding ammonium polyacrylate, solid content controls 15%.
(2) utilize and ultrasonicly add dispersed with stirring solid-liquid system, jitter time continues 40min, and the slurry temperature of dispersion controls at 30 DEG C-35 DEG C;
(3) scattered solid-liquid system is crossed 600 order wire mesh screens, collect the slip of screen cloth;
(4) utilize vertical centrifugal pump by slurry pipeline transport in hydrocyclone, the outlet pressure of vertical centrifugal pump controls at 0.8Mpa, and the import slip flow-control of cyclone is at 20m
3/ h, the overflow outlet pulp flow amount of cyclone controls at 1.8m
(5) SEM/PSD/BET(SEM/laser particle size analysis/specific area is utilized to detect) overflow outlet slip is detected, grading time controls at 80min, classification obtains even particle size distribution, bulky grain (>=1.2 microns) is few, and average grain diameter is at the qualified silver powder slip of about 400nm.
At same materials metal nano silver powder, under identical condition of work, same process parameter, carry out classification with ethanol, deionized water, the deionized water that adds dispersant for medium respectively, products obtained therefrom detects data.
(1) with the average grain diameter that PVD legal system the is standby nano-silver powder that is 980nm as the raw material of classification, joined and add in the deionized water solution of ammonium polyacrylate, degree content controls 15%.
(2) utilize and ultrasonicly add dispersed with stirring solid-liquid system, jitter time continues 40min, and slurry temperature controls at 30 DEG C-35 DEG C;
(3) scattered solid-liquid system is crossed 600 order wire mesh screens;
(4) just slurry pipeline transport is in hydrocyclone to utilize vertical centrifugal pump, and the outlet pressure of vertical centrifugal pump controls at 1.5Mpa, and the import slip flow-control of cyclone is at 24m
3/ h, the overflow outlet pulp flow amount of cyclone controls at 2.2m
(5) SEM/PSD/BET(SEM/laser particle size analysis/specific area is utilized to detect) overflow outlet slip is detected, grading time is empty only at 80min, classification obtains even particle size distribution, bulky grain (>=1.2um) is few, and average grain diameter is at the qualified silver powder slip of about 400nm.
At same materials metal nano silver powder, under identical condition of work, same process parameter, carry out classification with ethanol, deionized water, the deionized water that adds dispersant for medium respectively, products obtained therefrom detects data
From above-mentioned two groups (table 1-2) result displays, under same process condition, the deionized water adding ammonium polyacrylate is used to do classification medium, compare with just doing classification medium by deionized water and just do classification medium with alcohol, have many good qualities: not only output is high, good dispersion, does not have bubble to produce in classification process, and the more important thing is safety, save economical.