www.pengnuochemical.com Shijiazhuang Pengnuo Technology Co., Ltd.
EVA(CAS:24937-78-8), short for Ethylene-vinyl acetate copolymer, is a crucial category within the ethylene copolymer system. In the international market, all types of ethylene-vinyl acetate copolymers are collectively referred to as EVA. However, in China, the industry classifies EVA into three major categories—EVA resin, EVA rubber, and VAE emulsion—based on the difference in vinyl acetate (VA) content, with each category featuring distinct preparation processes and application fields.
I. Core Preparation Processes of Various EVA Categories
The technological differences between different EVA categories lie primarily in the regulation of vinyl acetate content and corresponding molding methods, while VAE emulsion also involves a special polymerization process.
EVA Resin
Products with a vinyl acetate content of less than 40% are classified as EVA resin, which is mostly prepared via high-pressure bulk polymerization or solution polymerization processes. In a high-pressure reactor, ethylene and vinyl acetate monomers undergo copolymerization under the action of an initiator. The synthesis of resins with different vinyl acetate contents is achieved through precise control of reaction pressure, temperature, and monomer ratio. Such resins typically require subsequent processing such as granulation to form granular solid finished products, facilitating storage and further processing.
EVA Rubber
Products with a vinyl acetate content ranging from 40% to 70% are known as EVA rubber due to their excellent flexibility and elasticity. Its preparation process is somewhat similar to that of EVA resin, but greater emphasis is placed on controlling the product’s elasticity. During the polymerization stage, the catalyst and reaction conditions of the reaction system are adjusted to enhance the flexibility of the polymer chains. Some processes also include a cross-linking modification step to improve elasticity and weather resistance, and the final product is mostly in the form of block or sheet elastic solids after molding.
VAE Emulsion
Products with a vinyl acetate content between 70% and 95% are VAE emulsion, which is prepared using a unique medium-pressure emulsion polymerization process, with the ethylene mass fraction required to be controlled between 10% and 40% (the conventional range is 14%-18%). The key to the process lies in the selection of protective colloids, as different protective systems directly affect emulsion performance:
When polyvinyl alcohol is used as the protective colloid, the resulting emulsion has strong adhesion, fast curing speed, and excellent bonding strength to PVC films, but it has insufficient water resistance and cannot be compatible with borax or dextrin.
If a composite protective system of nonionic surfactant and carboxymethyl cellulose is adopted, the emulsion can balance water resistance and PVC adhesion, and is also compatible with borax and dextrin, with only slight deficiencies in wet adhesion and curing speed.
Ultimately, through emulsion polymerization, a milky white or pale yellow liquid emulsion finished product is formed.
II. Diverse Application Scenarios of Various EVA Categories
Due to performance differences, different EVA categories have focused application fields, covering multiple sectors such as industry, daily life, and medical care.
EVA Resin
With good processability, low-temperature resistance, and chemical resistance, EVA resin is a commonly used raw material for plastic product processing. In the packaging field, it can be used to produce food cling film and buffer packaging materials; in the building materials sector, it can be made into door and window sealing strips and solar cell encapsulant films, and its excellent light transmittance and aging resistance can ensure the long-term stable operation of solar cell modules; in addition, it can be added to plastics as a modifier to improve the flexibility and impact resistance of materials.
EVA Rubber
Its core advantages of high flexibility and elasticity make it an ideal raw material for rubber and plastic products. In the footwear industry, it is widely used to make midsole of sports shoes, providing excellent cushioning and shock absorption effects for shoes; in the daily necessities field, it can produce yoga mats, anti-slip mats, and other products; in the industrial sector, it can be made into seals, hoses, etc., adapting to various flexible sealing and transmission scenarios.
VAE Emulsion
As the core base material of environmentally friendly water-based adhesives, VAE emulsion has the most extensive application scenarios. The adhesives made from it are non-toxic, odorless, non-flammable, and non-explosive, and have the characteristics of fast drying, flexible adhesive film, high bonding strength, acid and alkali resistance, and wear resistance, and their performance can be expanded through modification.
In the non-woven fabric and sanitary materials field, it can be used for bonding disposable products such as sanitary napkins, diapers, and surgical caps;
In the packaging field, it is suitable for food packaging, paper-plastic composite, and commodity label sealing;
In the building materials and home furnishing sector, it can meet the bonding needs of building decoration, carpet backing, and furniture manufacturing;
In addition, it can also be applied to industrial scenarios such as electrostatic flocking, PVC film lamination, and hot-melt sealing, fully complying with the current development direction of environmental protection and high performance in the adhesive industry.
Post time: Dec-04-2025