Therefore, in terms of PVC coloring, fully consider the characteristics of commonly used resins and related modifiers, and blend the characteristics of color paste. When selecting additives, we should pay attention to the following three problems:

1. Production and processing reliability

Some components in the additive will promote the dissolution of the resin. For example, iron ion and zinc ion are metal catalysts for PVC resin dissolution. Therefore, the use of compound (red, yellow, brown and black) pastes or reactive zinc oxide, zinc sulfide and lithopone type of milk color paste will reduce the heat resistance of PVC resin.

Some additives will react with the dissolved substances of PVC resin. If the alkali resistance of group blue paste is poor, then in the production process of PVC color, it will interact with the dissolved PVC hydrogen chloride, and lose the required color.

2. Mobility

Migration occurs only in plasticized PVC products, but also in the use of dyes or inorganic pigments. In other words, transportation is a part of soluble dye or organic pigment existing in the surrounding organic solvent. According to the tackifier penetrating into the surface of PVC products, these dissolved pigment particles are also sent to the surface of the product, which will form the degradation loss of gloss, organic solvent gloss loss or frost.

The other is "fouling.". It refers to that additives are dispersed from the production system due to the poor compatibility or incompatibility of the colorants in the coloring production process, and are accumulated on the surface of the production equipment (such as the inner cavity of the barrel and the inner cavity of the die hole of the extruder).

3. Weather resistance

It refers to the color paste to accept a variety of weather endurance ability. It includes visible light and ultraviolet light, moisture, temperature, air chlorination and organic chemicals encountered during the service life of the product. Important weather resistance, including the durability of non retreat, delamination resistance and process performance.

Organic pigments, on the other hand, have different structures. In addition, in the formula with milk color paste, the aging resistance of color paste will be relatively poor.

The discoloration, darkening or color change of color paste is generally caused by the reflection gene of color paste. This kind of reflective gene can work with water in the air or organic chemicals: acid and alkali.

For example, cadmium yellow can fade under the effect of moisture and sunlight. Lisol red has good light resistance and is suitable for most indoor applications, but it is more serious when used outdoors with acid and alkali.

Source: PVC profile manufacturer www.zhongshanlida.cn