The term “food conveyor belt” is no stranger to us. Most of the processed foods we purchase in our daily life are inseparable from food conveyor belts.
First, the material of the food conveyor belt
The food conveyor belt is made of non-toxic materials, non-toxic, odor-free, smooth surface, suitable for transporting food and food materials.
The main material of the non-toxic food conveyor belt is PU type. Because PVC, polyethylene, etc. contain harmful components, it is now used in the food industry for PU-type conveyor belts.
The material is PVC, polyethylene, polythene, PP, plastic steel ACETAL, PE, nylon, PA, etc., according to the specific food, there is a corresponding special conveyor belt, such as: the aquatic conveyor belt requires the grid to seep water, but also Anti-corrosion, easy to clean.
Commonly used are: vegetable conveyor belts, special conveyor belts for snack foods, special conveyor belts for beer, and special conveyor belts for seafood and aquatic products.
Second, the causes of aging of food conveyor belts are mainly as follows
Under the repeated action of mechanical stress and continuous friction with the idler, the conveyor belt will break the rubber molecular chain to form a free radical, trigger the oxidative chain reaction and form a force chemical process. Mechanically broken molecular chains and mechanically activated oxidation processes. Which one can prevail depends on the conditions in which it is located. In addition, it is easy to cause ozone cracking under stress.
The shorter the light wave, the greater the energy. What is damaging to rubber is the higher energy of ultraviolet light. In addition to ultraviolet light directly causing the breakage and cross-linking of rubber molecular chains, rubber generates free radicals by absorbing light energy, which initiates and accelerates the oxidation chain reaction process. Ultraviolet light plays a role in heating. Another feature of light action (unlike heat) is that it mainly occurs on the surface of the oak. For samples with high gel content, there will be reticular cracks on both sides, the so-called "outer layer cracking".
There are two aspects to the effect of moisture: when the rubber is exposed to humid air or immersed in water, it is easily destroyed. This is because the water-soluble substances and water-clearing components in the rubber are extracted by water. Caused by hydrolysis or absorption. Especially in the alternating action of water immersion and atmospheric exposure, the rubber damage will be accelerated. However, under certain circumstances, moisture does not have a destructive effect on rubber, and even has the effect of delaying aging.
Increasing the temperature can cause thermal cracking or thermal crosslinking of the rubber. But the basic role of heat is activation. Increasing the rate of oxygen diffusion and activating the oxidation reaction to accelerate the oxidation reaction rate of the rubber is a ubiquitous phenomenon of aging - thermal aging.
Oxygen undergoes a free radical chain reaction with rubber molecules in the rubber, and the molecular chain is broken or excessively crosslinked, causing a change in rubber properties. Oxidation is one of the important reasons for rubber aging.
The chemical activity of ozone is much higher than that of oxygen, and it is more destructive. It also breaks the molecular chain, but the effect of ozone on rubber is different depending on whether the rubber is deformed or not. When it is used as a rubber for deformation (mainly unsaturated rubber), a crack perpendicular to the direction of stress action occurs, that is, "ozone cracking"; when it acts on a deformed rubber, only an oxide film is formed on the surface without cracking.
There are other reasons for this: the chemical factors, chemical ions, high-energy radiation, electricity and biology.