Analysis of EVOH Raw Material for High Barrier Pesticide Plastic Bottles

2019-08-27 15:08:07

Ethylene/vinyl alcohol resin (EVOH) is a copolymer formed from ethylene and vinyl alcohol units, invented by Japan, with high functionality and thermal plasticity. Rely on the hydrogen radicals in the molecular chain and between the molecules of hydrogen to form a strong bond, so that EVOH exhibits excellent gas barrier properties. With the development of co-extrusion technology, EVOH has achieved significant growth in the application of food packaging as the center, and it has now become synonymous with gas barrier materials. In addition, it has expanded properties such as fragrance protection, oil resistance, solvent resistance, non-chargeability, printing characteristics, transparency, gloss, high rigidity, environmental adaptability, and biocompatibility, and it is used in many areas other than food packaging. There are various functions. The annual global demand exceeds 90,000 tons, and there is an annual growth of nearly 10%.

High-resistance insulation molding products

Representative barriers for EVOH, such as jelly cups, miso soup cups, rice trays, etc., which are widely used in Japan, are formed by deep drawing of extruded multilayered sheets in a heated mold such as a mold. Processing). Nippon Synthetic Chemical Industry Co., Ltd. was the first company to develop a product with a high ethylene content that is easily thermoformed. However, with the increase in demand for high barrier properties in the market, special materials for thermoforming have excellent barrier properties and thermoformability. Has been developed and used. With the increasing use of containers that can replace metal cans and achieve long-term preservation, the need for high barrier properties will increase.

Nippon Synthetic Chemical Industry Co., Ltd. developed Soarnol BX6804B, a high-resistance insulation molding product, based on market requirements. It is now the product with the highest gas barrier properties in thermoforming products. It is widely used in containers such as jelly cups and rice trays.

Back-feed additives

The lightweighting of plastic packaging materials, the sorting, recycling and recycling of waste plastic containers are the development trend of packaging materials. Because EVOH has excellent gas barrier properties and can be made thinner than other gas barrier resins, it can contribute to the lightweighting of packaging materials.

In addition, the packaging material using EVOH has a multi-layered structure and cannot be easily recovered like a container made of a single material, and therefore needs to be recycled. Raw material sheets such as jelly cups and trays, when deep-formed or blown, will generate waste materials such as excess scraps or flashes. If these waste materials are discarded, they are not good for the environment and economy. Therefore, the production enterprises set back layers in the multi-layer container structure to reuse the waste materials. However, this return layer is a mixture composed of a polyolefin-based resin used in the inner and outer layers of the multilayer container and a non-compatible component such as a barrier layer EVOH, and it may be deteriorated in appearance due to poor flow and crystallized due to EVOH repulsion. Point and cracking occur. In addition, when a pigment containing a component such as titanium oxide is added, EVOH and the pigment easily aggregate. In order to solve these problems, feed back layer additives have appeared in the market. Those auxiliaries formed in the waste and formed into the back layer, to a certain extent, to alleviate the above problems, but did not completely solve the problem, and sometimes even make the back layer yellow or red.

In order to solve these problems, Nippon Synthetic Chemical Industry Co., Ltd. has successfully developed a new feed additive RG500. RG500 is a polyolefin resin that can significantly improve the compatibility of EVOH, and it can significantly improve the phenomenon of crystal defects and cracking caused by poor flow and EVOH repulsion. The above figure shows the electron microscope observation of the section of the back layer. Compared with the effects of the previous additives, the particles of EVOH after mixing with RG500 become smaller and evenly dispersed, and the effect of the compatibility is significantly improved. Therefore, after using RG500, the recycling of EVOH multi-layer containers is very worthwhile.

Environmentally compatible resin

The structural components of EVOH are only carbon, oxygen, and hydrogen and do not contain plasticizers, crystallization catalysts, and antioxidants as in other thermoplastic resins. No harmful substances such as halogen compounds and nitrogen oxides are generated during combustion, and the heat released by combustion is only 2/3 of the polyolefin resin. Therefore, EVOH is a satisfactory material in both environmental and safety aspects. In addition, the above-mentioned high-resistance (thinning) and recycling technologies are also powerful proofs of the good environmental adaptability of EVOH resins.