New Technology Helps to Accelerate Coatings Development

POTSDAM,  Germany  -  Coatings  manu- facturers  are  now  able  to  monitor  the production  of  paints,  varnishes  and adhesives continuously and in real time, allowing  them  to  design  more  efficient processes,  thanks  to  researchers  from the  Fraunhofer  Institute  for  Applied Polymer Research IAP and the Potsdam- based company PDW Analytics GmbH.

When developing new coatings, man- ufacturers want to know precisely what goes  on  in  the  reaction  containers  and how  the  sizes  of  the  particles  change during the process. Normally, manufac- turers take a sample of the coating, thin it down and analyze it. The properties of a  coating  can  change  during  this  time, and  the  act  of  thinning  can  also  affect the  sample.  For  instance,  smaller  par- ticles may clump together to form larger particles. Consequently, the particle size in the sample will not necessarily be the same as that in the reaction container.

In  the  future  this  process  will  be simpler,  quicker  and  more  precise,  as manufacturers  will  be  able  to  analyze wall paints, varnishes or even adhesives inline. They will no longer need to take samples, but can analyze a product continuously and in real time directly during the manufacturing process. This is made possible  by  a  new  sensor  that  has  been developed by the staff of PDW Analytics GmbH, and integrated by the researchers from  the  Fraunhofer  Institute  into  their existing process development system.

At  the  heart  of  this  technology  is  a sensor  based  on  photon  density  wave spectroscopy,  a  process  developed  by PDW  Analytics.  This  sensor  works  by radiating laser light into the liquid wall paint via optical fibers. The intensity of the  light  is  modulated  up  to  the  giga- hertz range. Next, the method analyzes how,  depending  on  the  frequency,  the light  propagates  in  the  liquid.  From these  data  the  size  of  the  individual particles  is  determined.  The  research- ers at the IAP have developed reference systems  by  using  the  photon  density wave  spectroscopy  technique  to  mea- sure  various  samples  with  particles  of a given size.

IAP researchers  use  the  sensor  to reconstruct and analyze production processes for their customers. For some time now,  the  scientists  have  been  working with a process development station that, in  the  case  of  suspensions  with  particle sizes  of  between  one  micrometer  and one  millimeter,  enabled  them  to  determine not only viscosity and heat flow but also  the  particle  sizes.  An  infrared  sensor  additionally  detected  the  chemical changes and showed to what extent the chemical reactions have advanced.

Customers  can  opt  to  have  their  processes analyzed at the IAP, such as when a company is unable to resolve an issue by itself. Alternatively, because the whole system  is  transportable,  they  can  use  it on site at the company’s premises. Typi- cal  questions  are:  Can  polymerization time be reduced? How can uncertainties in the process be eliminated and material properties  improved  -  for  example,  how to ensure that adhesives adhere better or wall paint covers better?