PVC Paste Resin

PVC paste resin, also known as PVC emulsion resin, with fine powder and immobility, is often prepared by emulsion and micro-suspension method. Polyvinyl chloride paste resin is mixed with the plasticizer and then stirred to form a stable suspension, which is then made into PVC paste, or PVC plastisol, PVC sol. Paste PVC is named after its highly dispersible powder used for paste processing. Because of its excellent paste-forming properties and good dispersion properties, it is mainly used in the field of soft materials of PVC resin.

Compared with PVC suspension resin, Paste PVC has the following advantages:

• The processing equipment is cheap.
• The mold is simple and cheap.
• It can be made into a special shape.
• Easy to foam.
• The products are heated less frequently, and can be produced in small quantities and with multiple varieties.

PVC paste resin has been widely used in the production of artificial leather, gloves, wallpaper, adhesives, automotive sealants, steel coating, coatings, advanced footwear and other fields.

Used in the processing of drop plastic cotton products. The cotton plastic products made by the drop molding process is made of various knitted cotton cloth and a variety of blended base cloth as raw materials. White or colored PVC small particles are dripped on the surface. This cotton-plastic cloth has excellent wear resistance, non-slip, heat insulation, insulation and perspiration properties. The gloves made are the replacement products of various knitted, nylon, canvas and labor insurance gloves.

Used in the processing of plastic products in the automotive industry. The plastisol prepared with PVC paste resin can be used to make car seat armrests, dashboard skins, steering wheel skins and other automotive interior decoration parts through sugar molding, rotational molding, dip molding and other processes. These interior trim parts can faithfully reproduce the delicate mold surface patterns and configurations, and all have good heat resistance, impact resistance and tear resistance.

Polyvinyl chloride paste resin has fine particle size and immobility. So it is usually mixed with the plasticizer, such as DOP plasticizer, to form a stable suspension after stirring. Then the PVC plastisol or PVC sol produced can be directly used to process into final products. In the process of paste making, add various fillers, diluents, heat stabilizers, foaming agents and light stabilizers according to the needs of different products.

At present, the industrial production methods of PVC paste resin mainly include emulsion polymerization, micro-suspension polymerization and mixed micro-suspension.

Emulsion polymerization

Emulsion polymerization formulations mainly include vinyl chloride VCM, water, water-soluble initiators and emulsifiers. In this method, vinyl chloride and water under the action of water-soluble initiator and emulsifier to obtain polyvinyl chloride paste resin. Emulsion polymerization has strict requirements on stirring, and the initiation is carried out in the aqueous phase. The commonly used initiator is water-soluble persulfate.

In general, the particle size of the latex obtained by emulsion polymerization is less than 0.2μm. In order to achieve the purpose of increasing the particle size of the latex, an emulsion seed polymerization method was developed to increase the particle size of the latex to about 1.0μm. But only a reasonable particle size is not enough, it is necessary to have an appropriate particle size distribution. In this way, PVC paste resin with excellent performance can be obtained.

Emulsifiers are important in emulsion polymerization. The amount used determines the particle number of the initiator and plays a major role in the final latex particle size. Especially in seed generation, the use of high initiation rate and low concentration of emulsifier can narrow the size distribution of latex particles. The latex particle size and its distribution are the key to the production of PVC emulsion resin by emulsion method.

Microsuspension Polymerization

Its preparation process is that part of vinyl chloride is made into a stable milky state by mechanical homogenization first, and then the polyvinyl chloride paste resin is obtained by polymerization. This method must use oil-soluble initiators. The PVC paste resin produced by this method has excellent fluidity, relatively simple reaction, less emulsifier dosage, relatively stable product quality. A large particle size latex can be obtained by one polymerization. Both thermal stability and water resistance of the resin are improved. In addition, the latex has the highest solid content, usually around 48%, and can even reach 50%, which reduces heat energy consumption. In the production process, it is necessary to pay attention to the selection of the appropriate composite emulsifier and particle modifier system, the homogenization of the components of the polymerization system, the stirring speed, and the appropriate ratio of water to monomer.

Mixed Microsuspension

In the method, the seeds prepared by emulsion polymerization and the seeds prepared by micro-suspension polymerization are mixed, and then the micro-suspension polymerization is carried out. The purpose of this method is to prepare PVC paste resin with large particle size and bimodal distribution.

The method has the following characteristics:

1. The polymer is fed at one time without homogenization or only partial homogenization.
2. The process is simple. Compared with emulsion polymerizationmethod, the process of continuously adding emulsifier is saved.
3. The use of oil-soluble initiators ishigh safety, especially the use of redox system initiators, as long as one component is not added to the reaction, the reaction cannot be carried out.
4. Low energy consumption. Because the solid content of latex is as high as 50%, whichcan save heat energy consumption.
5. The latex has a large particle size and a bimodal distribution, which is very important to improve the processing and application performance of paste PVC.