The yellowing and hardening of the medical silicone tubing are mainly formed by aging. Controlling yellowing and hardening is the process of controlling aging. But aging is divided into thermal aging, oxygen aging, ozone, gas corrosion aging, and heavy metal oxidation aging. Reactive aging, UV aging, etc. In addition, it is divided into material aging and pH imbalance. chain scission, etc.

Therefore, the following 10 things should be paid attention to when producing medical silicone tubing.

Precautions for the production of medical silicone tubing

1. The yellowing resistance of the raw material itself, for example, the aging resistance of NR is worse than that of SBR and BR.

2. Matching of the accelerator system. Accelerators can use DM and M to achieve yellowing level 4, but the entire system needs to be adjusted. The use of yellowing resistance accelerators such as dithiocarbamates is beneficial for yellowing but at the expense of great physical properties and handling. The faster the vulcanization rate, the less chance of chain scission, and the degree of aging are suppressed. But at the same time sacrificing comprehensive properties. Because the crosslinks generated by fast vulcanization and slow vulcanization are different. Such as tensile tearing, etc. are greatly affected. But elastic brittleness will increase.

3. The control of the hot pressing temperature, the temperature should not exceed 150 degrees, and even if the extreme point is below 140 degrees, the effect is better. Otherwise, many materials will undergo a process of thermal aging. High temperature is an important factor in material aging.

4. The use of titanium dioxide, purpose of using titanium dioxide is to form a mirror reflection on the surface so that ultraviolet rays cannot penetrate the rubber, which is also similar to surface treatment. The larger the dosage, the better the anti-aging effect, the finer the particle size, and the better the anti-aging effect.

5. The control of heavy metals, such as zinc oxide, light calcium, and oil contains heavy metals, especially some low-priced materials. If the heavy metal content is high, the heavy metal will be oxidized and discolored. Yellowing is very easy to occur.

6. Use of oil: less oil should be added, especially the alkane group should not be added to general-purpose rubber for use, because of poor compatibility, the oil penetrates the surface and also dissolves the additives in the oil. brought to the surface. But sometimes people will find a strange phenomenon that when a cup of naphthenic oil and a cup of white mineral oil is exposed to the sun at the same time, the naphthenic oil will change color first, while the white mineral oil will not change color. It is considered that white mineral oil has better yellowing resistance.

7. Control of TS2 and T90: It should be slightly under-sulfur, and the more it reaches the positive vulcanization point, the more serious the chain breakage is. The broken chain is also aging. The effect of T90 is better than T100.

8. Adjustment of pH: The rubber compound is weakly acidic, which will have a slight inhibitory effect on the vulcanization reaction, and also control the aggravation of chain scission.

9, the use of antioxidants. BHT has a good protective effect on thermal oxygen and so on. SP will coordinate with MB production, and the effect is also ideal. Of course, the premise is that the material quality is excellent.

10. A general trick: As far as the main UV protection is concerned, add an anti-UV agent.

Summary

Newtop Medical is an experienced medical silicone tube manufacturer, we have several silicone extrusion molding production lines to meet customers’ custom medical silicone tubing needs. If you want to custom manufacture silicone tubes or other medical silicone products, then please contact us immediately.