I believe everybody is reluctant to use TPE, TPR plasti […]
I believe everybody is reluctant to use TPE, TPR plastic tool handles, toothbrushes, and a firm grip will feel sticky. Feel good TPE, TPR material in the process of processing, will not stick to the screw, the surface is better. There are many factors that affect the smoothness of TPE and TPR. Specifically, they focus on the following five points:
1. Selection of SEBS itself: Under the premise of the same oil-filling capacity, the structure of SEBS (star and line type) and the molecular weight will affect the hand feeling;
2, the type of oil and oil-filled oil: oil quality and type of choice (such as the same situation full of paraffinic oil than naphthenic hand feel smooth), the amount of oil-filled (moderate, too much too little feel is not good );
3. Control of TPE/TPR process during processing, such as temperature, extrusion speed, etc.;
4, adding some engineering plastics, not only can TPE modification, but also can affect oil absorption, improve the TPE feel, such as highly crystalline PE, PP, spit oil is more viscous;
5, the choice of additives: Here are the main TPE slip agent (slip agent), anti-adhesive agent (such as white carbon), and their use.
When all four points have been optimized and cannot be improved, everyone can consider adding a proper amount of TPE slip agent. TPE slip agent, full name TPE slip anti-stick lubricant, is an elastomer additives. It has excellent smoothness and good anti-blocking properties. As additives, generally according to different requirements, the addition amount is 0.05%-0.3%, after adding, it can effectively reduce the friction and adhesion between polymer and equipment, polymer and polymer, so that the processing speed and product quality get the largest Promote.
The following describes the mechanism of action of the slip agent (slip agent):
The main role of fatty acid amide additives in the production of polyolefin films is to impart smoothness characteristics. The addition of slip agents (eg, erucamide and oleamide) provides an intrinsic lubricant reservoir for the polymer matrix. After leaving the mold, the slip agent instantly migrates to the surface of the polymer film. Migration occurs because of poor compatibility between the fatty acid amide and the polymer. In the process, the fatty acid amide is soluble in the amorphous melt, but slips when the polymer cools and begins to crystallize. The solvent is then extruded out of the hardened polymer matrix and once it reaches the surface, the slip agent forms a lubricating layer, thereby effectively isolating the adjacent film layer.
The two most commonly used slip agents are erucamide and oleamide. Erucamide is made from a single unsaturated C22 erucic acid. The oleic acid amide is derived from C18 monounsaturated oleic acid. It is generally believed that oleic acid amide is a fast-release slip agent because it migrates to the surface of the film faster than erucamide.
Stearic acid amides are often used when fatty acid amides must also provide an anti-sticking effect. Stearoamide belongs to another class of slip agents and is mainly used in combination with oleic amide or erucamide. In general, inorganic release agents such as silica are the most commonly used, but in some applications where fatty transparency of the film is very important, it is necessary to use fatty acid amides to give the material an anti-sticking effect.