Guidelines for using DigiPrime 1500LA

Size Press Application

In this method the DigiPrime is mixed with starch at the desirable ratio based on targeted dry pick up and applied at the size press, typically at 7 to 11% total solids. The major concern with this application is to achieve a stable mixture of starch and DigiPrime. To help facilitate this we developed DigiPrime 1500LA having an improved tolerance to starches. This is a 35% solids emulsion of an EAA copolymer having a low ammonia level.

The best way we have found in practice to make mixtures of this material with starch is the following. A solution of the starch is first made and held at 55 °C. The DigiPrime 1500LA is diluted to the required solids with soft water at ambient temperature. The two components are then mixed together and diluted further if needed and used on the size press while still warm.

We have found that in practice some starches are more tolerant than others in combination with the DigiPrime. The starch ethers seem most compatible, giving coating mixtures with low and stable viscosity. Some native starches have been successful (with enzyme cooking), but cationic starches seem to give many problems as the DigiPrime itself is anionic. We advise customers to test compatibility with their own starch system first before doing any further trials.

Preparation of a Starch: DigiPrime 1500LA mixture:

1. Stir the starch and soft water at ambient temperature for 15 - 20 minutes.
2. Heat the mixture to 96 °C under agitation.
3. Continue to stir the mixture for 25 – 30 minutes while maintaining batch temperature at 92 – 96 °C.
4. Cool down to 55 °C and if necessary, adjust solids level due to any water loss.
5. Add the DigiPrime (at ambient temperature) under agitation and maintain batch temperature at 55 °C.
6. According to the following guideline, the coating mixture is expected to have Brookfield viscosity (#3/60 rpm) of less than 75 cps for at least 24 hours.

Suitable starches for formulating with DigiPrime 1500LA