The decomposition temperature of pure polyvinyl chloride (PVC) resin is very close to the plasticization temperature. When heated to 130°C~140°C, it will decompose and release hydrogen chloride (HCl) gas, which has great effects on the material itself and the environment. influences. In actual use, pure polyvinyl chloride resin is rarely used to process products, and various additives are added during processing to improve the performance of polyvinyl chloride.
When PVC is used as a medical material:
The product needs certain functionality, and certain functional additives need to be added to PVC;
To inhibit the decomposition of HCl during PVC processing, a heat stabilizer is required;
In order to facilitate processing and increase the flexibility of PVC, plasticizers, lubricants, etc. need to be added.
Functional filler
1. X-ray opaque filler
In order to track the position or state of the catheter entering the body during the operation, the catheter usually needs an opaque X-ray. Commonly used X-ray opaque fillers include barium sulfate, bismuth subcarbonate, bismuth oxychloride, bismuth oxide, aluminum tungsten oxide, and tantalum oxide.
Spinal anesthesia needle
Enhanced anesthesia catheter
2. Pigment
Sometimes for the overall appearance and difference of the product, some medical devices will add pigments or dyes to form colored medical devices. Generally, the proportion of pigments is less than 1%. Commonly used pigments in PVC products such as titanium dioxide (TiO2), phthalocyanine blue, phthalocyanine green, etc. 1% TiO2 can achieve a uniform and light-proof white. Phthalocyanine blue and phthalocyanine green are organic pigments with strong colorability, and 0.1% can produce medium-tone colors.
3. Magnetic substance
In magnetic resonance technology, the catheter needs to be paramagnetic, and paramagnetic substances are usually added to the catheter. Dysprosium oxide and superparamagnetic iron oxide are two commonly used paramagnetic substances. For example, the passive visibility catheter used in intravascular magnetic resonance technology adds paramagnetic material to the catheter wall, or coats the surface of the catheter with a coating of paramagnetic material.
stabilizer
Commonly used stabilizers are mainly organic composite stabilizers such as calcium, magnesium, zinc, and tin, with auxiliary stabilizers such as phosphite and epoxy soybean oil added. It has the advantages of non-toxicity, chemical resistance, good thermal stability, and good compatibility with PVC.