Raw Plastic Virgin/2904/2951/3201/3251/3851/4405/4451/EVOH Resin/High Barrier/Packing Material/EVOH

Combining the processability of vinyl polymer with the blocking effect of vinyl alcohol polymer, the ethylene-vinyl alcohol copolymer not only shows excellent processing performance, but also shows excellent blocking effect on gas, odor, fragrance, solvent and so on.

Due to its thermal stability in combination with ethylene, multilayer containers containing EVOH barrier layers are fully reusable.

EVOH(Ethylene vinyl alcohol copolymer) Ethylene vinyl alcohol copolymer

EVOH has been the most widely used high barrier material. The film types of this material in addition to non-tensile type, there are biaxial tensile type, aluminum evaporation type, adhesive coating type, etc., biaxial tensile type and heat resistant type for aseptic packaging products.

The barrier property of EVOH depends on the content of ethylene, in general, when the content of ethylene increases, the gas barrier decreases, but it is easy to process.

EVOH is characterized by excellent gas barrier and excellent processability, in addition to excellent transparency, gloss, mechanical strength, scalability, wear resistance, cold resistance and surface strength.

In the field of packaging, EVOH is made into a composite film intermediate barrier layer, which is used in all hard and flexible packaging; Used in the food industry for aseptic packaging, hot POTS and cooking bags, packaging dairy products, meat, canned fruit juices and condiments; In the non-food aspect, it is used for packaging solvents, chemicals, air conditioning structural parts, gasoline drum lining, electronic components, etc.

In terms of food packaging, EVOH plastic containers can completely replace glass and metal containers, and many domestic aquatic companies use PE/EVOH/PA/EVOH/PE five-layer co-extruded film vacuum packaging for exporting seafood. At the same time of accelerating the research of EVOH composite film, the EVOH tensile orientation is also studied abroad. The gas barrier performance of the new EVOH film is 3 times that of the existing high-performance non-stretched EVOH film. In addition, EVOH can also be used as a barrier material coated on other synthetic resin packaging materials to enhance the barrier performance.

EVOH products can not only be used in the production of film, but also can be widely used in cosmetic flexible packaging, floor heating pipes, jelly cups and pesticide bottles, etc. EVOH as a non-toxic environmental protection material, not only can improve people's quality of life, but also plays an important role in environmental protection.

EVOH(ethylene-vinyl alcohol copolymer):

It is these characteristics that enable plastic containers containing EVOH barrier layers to replace many glass and metal containers in food packaging.

(1) Chemistry and properties

Of the polymers available today, polyvinyl alcohol (PVA) has the lowest gas permeability. However, PVA is water-soluble and difficult to process.

The preparation method of EVOH is: first, ethylene and vinyl acetate are copolymerized, and then the copolymer is hydrolyzed to obtain ethylene-vinyl alcohol. Therefore, a high degree of barrier effect is still retained, and there is a significant improvement in moisture-proof and processing properties.

In terms of properties, EVOH copolymer is highly crystalline, and its properties are mainly determined by the relative concentration of its copolymer monomer. Generally speaking, when the ethylene content increases, the gas barrier property decreases, the moisture resistance improves, and the resin is easier to process.

The most notable feature of EVOH resin is its gas barrier effect. It is used in the packaging structure to improve the retention of flavor and quality by preventing the infiltration of oxygen. In the use of inflatable packaging technology, EVOH resin effectively retains the carbon dioxide or nitrogen used to protect the product.

Due to the presence of hydroxyl group in the molecular structure of EVOH resin, EVOH resin has hydrophilic and hygroscopic properties. When the moisture is absorbed, the barrier properties of the gas will be affected.

However, the moisture content in the barrier layer can be carefully controlled, and this can be done by using multilayer techniques to wrap the EVOH resin layer with a strong moisture insulating resin such as polyolefin.

(2) Oil resistance

EVOH resin also has strong resistance to oil and organic solvents. After 1 year of immersion in various solvents and oils at 68°F, the percentage weight gain is 0% for solvents such as cyclohexane, xylene, petroleum ether, benzene and acetone, 2.3% for ethylene glycol, 12.2% for methanol, and 0.1% for para salad oil.

(3) Thermal/mechanical properties

EVOH resin has high mechanical strength, elasticity, surface hardness, wear resistance and weather resistance, and has strong antistatic property. EVOH films are highly transparent because of their high gloss and low fog.

EVOH resin is all commercial strong barrier resin, the highest thermal stability of the resin, this property allows the processing of waste can be recycled and reused, recycled materials contain up to 20% more EVOH.

(4) Processing

There are three basic ways to use EVOH to provide compartments in multilayer structures, they are:

Co-extrusion structure. EVOH resin is combined with polyolefin or polyphenolamine to form a framework.

EVOH films are laminated onto other substrates or coated with other materials.

Use EVOH resin for coating various substrates or single-layer containers.

It can be easily processed on conventional manufacturing equipment without special changes.

With commercial equipment, EVOH resin is suitable for the following processes: extrusion of single or multi-layer films; Sheet and profile co-extrusion; Coextrusion blow molding; Coextrusion coating; Laminating (or laminating) and injection molding.

Secondary processing of EVOH resin frames or EVOH films such as thermoforming, vacuum forming and printing are easy to carry out. Like other polymers, EVOH resins can be modified by overheating.

Coating techniques including multilayer coatings or co-extrusion coatings can also be used to produce multilayer structures, and the resulting structure is very similar to the co-extrusion structure. EVOH resin can be sprayed, immersed or roller coating methods. The production of containers containing carbonated beverages may achieve the purpose of blocking solvents, flavors or odors.

EVOH resins have poor adhesion to most polymers, and to overcome this difficulty, specially designed bonding resins or "bonding resins" are used. With the exception of nylon, EVOH resin can adhere well to nylon without the use of bonding resin.

(5) Application

Barrier layer structures containing EVOH resins are used in all hard and flexible packaging and in all types of food processing including aseptic, hot injection and pressure cooking. Products packaged with EVOH materials include: condiments (soy sauce), tomato sauces, juices, edible pastes, meat products, cheese products, and processed fruits.

Non-food applications include solvents, chemicals and packaging for pharmaceutical-related products.

Manufacturers of fuel tanks, fuel lines and air conditioning equipment for motor vehicles are evaluating the use of EVOH structures to reduce hydrocarbon and/or freon emissions.

Ethylene-vinyl alcohol copolymer (EVOH)
Combining the processability of ethylene polymer with the barrier effect of ethylene alcohol polymer, ethylene-vinyl alcohol copolymer not only shows excellent processing performance, but also shows excellent blocking effect on gas, odor, fragrance,solvent, etc.Due to its thermal stability in combination with ethylene, multilayer containers containing EVOH barrier layers are completely reusable.It is these features that enable plastic containers containing EVOH barrier layers to replace many glass and metal containers in food packaging.