Common Problems and Selection of Additives
Common problems during molding and production processes and the corrective measures are explained below. Please refer to the information below when selecting additives.
Frequently Asked Questions
- Influence of
Additives
during Molding - Extension of
Heat Stability - Extension of
Weathering Stability - Discoloration
- Impairment of
Design Aesthetics
-
Impairment of Design Aesthetics
Q14
What are blooming and bleeding?
A14
Blooming and bleeding refer to phenomena in which additives and/or plasticizers in the polymer migrate to its surface. The discharge of these substances in the form of solid or liquid impairs the design aesthetics of the products. In general, blooming refers to the discharge of solid substances, whereas bleeding refers to the discharge of liquids.The cause is that the compatibility between the polymer and the additive is poor.
Corrective Measures
- 1
- Use additives that have good compatibility with the polymer. For example, select an additive with a solubility parameter (SP value) close to that of the polymer.
- 2
- With respect to migration properties, select additives that are suitable for the environment in which the plastic product will be used (particularly with regard to temperature). When polymers are used at high temperatures, or at relatively low temperatures, additives need to be selected in accordance with the molecular weight and heat resistance etc. of the additives.
Q15
What is fogging?
A15
Fogging refers to the phenomenon in which additives volatilize from polymers, so that they adhere to and fog the glass or walls etc., impairing the design aesthetics of the product.
Corrective Measures
- 1
- Use high molecular weight additives with low volatility.
- 2
- Select additives that are suitable for the environment in which the products will be used. With regard to the light stabilization of molded articles used in relatively high temperature environments, such as materials for automobile interiors, additives with higher molecular weight is better, as lower molecular weights additives such as HALS are prone to be fogging. Additives which have optimal molecular weights and compatibility should be selected.