Retention Aid

Retention Aid is the key to cost savings in paper mill. Retention aids are used wet end of the paper mill to improve retention of fine particles, fillers, additives & sizing agent during the formation of paper. Particularly retention aid is need to be added in alkaline paper making process, but not in acidic paper making process because in this process alum act as a retention aid. The modern paper making technology is alkaline paper making process. Moreover modern paper mill operate high speed paper machine and they increased the usage of recycled fibers. In this case the task of retaining is more challenging and paper machine runnability will be decreased. As a result the papermaking process becomes less economical. Hence the demand of retention aid is increased to saving cost.
The chemical most used as retention aids are polyacrylamide, polyethyleneimine.

Troubles of low retention:
Papermaking is in essence a filtration process. The paper machine wire cloth can be considered as a continuous filter; where a proportion of the solids in the stock is retained and some fine particles are drain through the wire cloth mesh with water and formed white water. The greater part of the white water is returned to the stock, with the result that the concentration of fines and fillers gradually increases. It should be retention otherwise face to following troubles:

  • Fine fiber particles and filler drainage
  • Higher additives and sizing cost
  • Increased deposits
  • Decreased runnability
  • More downtime for cleaning
  • Filling of wet-press felts
  • Bad paper sheet formation
  • Higher sewer losses

Function of retention aids
The best retention of fine particles and colloids in the papermaking process normally occurs when the zeta potential is near to zero and retention aid doing that. The main functions of retention aid are following:-

  • Accelerate drainage, hence increased machine speed
  • Improved retention of fines and fillers
  • Reduced wet-end additives and sizing usage
  • Reduced steam usage due to better surface contact
  • Reduce deposits
  • Reduce sheet breaks
  • Improves paper machine runnability
  • Improved paper sheet formation
  • Increased brightness
  • Cleaner white water system
  • Reduce downtime for cleaning
  • Overall, Increase the productivity

Disadvantages of retention aid
If retention aid is used as overdoses than a highly flocked sheet is formed. Moreover increase paper web break, two sideness and decrease paper machine runnability. Hence to optimize runnability it is need to be adding only the proper amount of retention aid.

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4 Responses to Retention Aid

  1. BIGLER says:

    But use of retention aids causes a contamination of the press felts and this reduces their dewatering ability and hence the capacity of the paper production.

  2. jayesh shah says:

    what is cetanic retention ? kindly suggest for catanic retention . water ph 4-4.5 (water reuse in pulp.

  3. Pankaj shah says:

    MICROTEC15 manufactured by Sterling Chemicals is the product with negatively charges silica particles.This is the right Retention Aid for hour requirement

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