With the continuous development of processed products, the development of polyvinyl chloride paste resin is very rapid. At present, the demand for it in the international market is increasing, and its development and utilization prospects are also very broad.
PVC paste resin can produce some special products, such as plastic products, foam artificial leather, microporous plastic, steel plate plastic layer, automotive decorative materials, electrical materials, etc.
It is widely used in artificial leather, decorative materials, floor leather, wall paper, industrial conveyor belts, sports grounds, paints, adhesives, toys, medical disposable gloves, daily decorative materials, electrical instruments and electrical tools and other fields.
Compared with traditional suspension resins, PVC paste resins have the following advantages:
- Less investment in equipment and simple processing technology.
- Simple and cheap mold.
- can be made into special shapes.
- easy to foam.
- The product has the characteristics of less heating times, and can be produced in a small amount and in many varieties.
1. Microsuspension method
First of all, make a part of VCM (5%) into a stable emulsion (with a particle size of about 1.0 μm) by mechanical homogenization, and then carry out polymerization (an oil-soluble initiator must be selected). The PVC paste resin produced by this method has excellent fluidity, less emulsifier consumption, and improved thermal stability and water resistance of the resin.
2. Emulsion method
The emulsion polymerization formula mainly includes VCM, water, water-soluble initiator and emulsifier. In particular, emulsion polymerization requires very strict stirring, and the initiation is carried out in the water phase, and the commonly used initiator is water-soluble persulfate. Generally, the latex particle size obtained by emulsion polymerization is less than 0.2 μm. In order to achieve the purpose of increasing the latex particle size, the emulsion seed polymerization method was developed to increase the latex particle size to about 1.0 μm.
In emulsion polymerization, if there is already generated high polymer latex, control the material ratio and conditions. In principle, VCM only polymerizes on the generated latex particles, and no longer forms new particles; this generated high polymer latex The polymer latex is like a seed crystal, hence the name “emulsion seed polymerization”. But only a reasonable particle size is not enough, it must have an appropriate particle size distribution in order to obtain a PVC paste resin with excellent performance.
3. The mixed method
The mixed production process mainly integrates emulsion polymerization and microsuspension polymerization. In the whole reaction process, seeds after emulsion polymerization, other emulsifiers, initiators, various auxiliary agents and VCM are added to participate in the reaction. The mixing method uses C16 and C18 mixed linear alcohols and sodium lauryl sulfate or lauric acid amine to form an emulsifier to form a micro-emulsion, and the polymerization reaction is mainly carried out in micro-droplets. Adding seeds after emulsion polymerization makes the overall particle size distribution bimodal.