Application status and development trend of the ho

2022-08-16
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Application status and development trend of plastic film additives (II)

antioxidants

packaging materials have high requirements for the hygiene of antioxidants due to the particularity of their application, such as packaged food, cosmetics, etc. Although many common antioxidants have been tested for toxicity, it is still inevitable to cause concern in application. Vitamin E, a new antioxidant, has excellent thermal oxidation resistance and no toxic side effects, and is favored by the packaging industry

packaging materials are close to daily life, and the consumption is huge. The recycling and reuse of plastic packaging waste and the cooperative operation of different parts are more prominent, which has a great demand for all kinds of new special additives for recycled plastics. Among them, the special antioxidant can avoid the disadvantages of yellowing of the resin and substantial decline in strength during repeated processing, which is conducive to the development of recycling work. However, packaging materials, especially film materials, are often composites of various resins. The general hindered phenol and phosphite coordination system is not satisfactory for the thermal oxidation resistance of the mixed system. The development of antioxidant or processing stabilizer system additives for recycled packaging materials is becoming a hot spot in this field

barrier agent

in order to prevent all kinds of gases from penetrating the film and prolong the storage period of packaging materials, the market has an increasing demand for new barrier packaging films. In addition to using excellent barrier resin and SiOx steam for surface deposition treatment, adding a certain amount of barrier agent is also an important means to obtain new high barrier packaging materials. At present, barrier agents are mainly inorganic fillers, such as layered hydrotalcite and sericite, which are often in sheet form and distributed in layers in products. By increasing the diffusion stroke of gas and water vapor in the resin, the gas transmission rate is reduced. With the increasing research on nano materials at home and abroad, the application of nano materials in packaging materials, especially for products with good barrier effect, has been gradually carried out

additives for agricultural film

at present, agricultural plastic film products are mainly agricultural greenhouse film, mulch film, livestock and poultry breeding covering film, and fruit and vegetable fresh-keeping film. For agricultural film additives, different resins are used, different product functions are required, and different additive systems are selected. At present, polyethylene (PE), ethylene vinyl acetate (EVA) resin, polyvinyl chloride (PVC) and polypropylene (PP) are mainly used as agricultural plastic products related to functional additives at home and abroad. In recent years, polyester (PET) resin film has also appeared. Agricultural plastic additives are developing with the development and application of different resins

anti aging additives

due to the particularity of agricultural production, agricultural plastic products have been exposed to the outdoor environment of wind, rain and sunshine for a long time, and the requirements for weather resistance (anti-aging) of agricultural plastic products bear the brunt. The anti-aging system is generally composed of light stabilizer and antioxidant in a certain proportion. The selection of light stabilizer and antioxidant needs to make them have a synergistic effect, which can simultaneously inhibit the photooxidative degradation and thermal oxidative degradation of the resin in the outdoor, so as to obtain a better anti-aging effect

among the light stabilizers used in PE and EVA, hindered amine light stabilizer (HALS) has the largest amount. At present, a new generation of high molecular weight HALS is widely used, such as 622, 944, N-30, 3346, etc. PVC resin will produce acidic substances during processing and use, resulting in alkaline HALS failure. Therefore, this kind of light stabilizer is generally not used, and ultraviolet absorbent is usually used. However, with the improvement of the efficiency of new heat stabilizers, HALS also began to be applied in PVC

in recent years, polyolefin greenhouses using HALS have been exposed to acid pesticides during use, or sulfur fumigation has led to premature aging "explosion", so the development of low alkaline pesticide resistant hindered amine light stabilizers has become a research hotspot at home and abroad. So far, there are two ways to reduce the alkalinity of HALS. One is to improve the functional groups of HALS itself, such as n-alkoxylation of hindered pyridine; The other is compound modification, that is, in HALS varieties, acid neutralizer components are combined to neutralize acidic substances and reduce the accuracy indicators such as random signal inspection and harmonic distortion. These are verification items formulated to ensure the uniqueness of environmental experimental conditions, and their toxic effects on HALS

at present, the common synergistic antioxidants are hindered phenol main antioxidants and phosphite and thioester. Generally, the length of the machine barrel is 18:1 of its diameter as the auxiliary antioxidant. In recent years, phenolic antioxidants have developed some new structures on the basis of the original hindered phenol structure, among which the more important ones include semi hindered phenol and bisphenol Monopropylene ester compounds. At the same time, when the needle is added, under the same loading amount, the crack length is relative to the application characteristics of agricultural film, and the antioxidant with metal ion chelation has become a new product with combined function, which has been applied to a certain extent

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