Conventional TPE and TPR do not have functional viscosity, but need to adjust the compounding system to obtain the required adhesion (adhesion). With the continuous deepening and expansion of the application of thermoplastic elastomers TPE and TPR, the adhesive properties of TPE and TPR (including self-adhesive and co-adhesive) may gradually be applied in different industries.
Regarding the viscosity of TPE materials, here are three different meanings of viscosity:
1. Self-adhesiveness of TPE material; refers to the strong adhesion of the surface of TPE material, similar to the surface coated with glue. This kind of TPE material with strong self-adhesiveness can be used to paste daily necessities to prevent it from falling or tipping over when touched. Similar TPE materials, a foreign TPE manufacturer has specialized research and development, and applied for a patent. In fact, in the conventional TPE compounding system, adding a tackifier with good compatibility with the main compounding system can improve the viscosity of the TPE material surface. This kind of stickiness is positive and is what users demand and hope.
2. Adhesiveness on the surface of soft TPE material. Some low-hardness TPE materials have a sticky feel on the surface of the soft TPE material due to the high content of oil components in the compound. This sticky feeling is caused by the oil in the formula. Generally, TPE (TPR) based on SBS is more prone to surface stickiness. This kind of stickiness is negative and is what users want to eliminate.
3. Viscosity problem during overmolding. The stickiness mentioned here refers to the fusion bonding between the TPE and the coated substrate (plastic) due to the close solubility sp or good compatibility when injection molding at high temperature. effect. The quality of the adhesion is mainly determined by the surface affinity of the TPE and the coated plastic (similar melting point, close polarity and surface tension, etc.)
The co-stickiness of TPE and TPR is numerous in application. Most plastics, a few non-metallic materials and metals can be bonded to TPE and TPR in a manner similar to co-bonding.
(1) Co-bonding of TPE, TPR and plastic
This is the most common co-adhesion. The co-bonding of TPE, TPR and plastic has a more familiar name in the industry-overmolding, also known as overmolding, overmolding, two-color/multi-color injection and so on. The encapsulation applications of TPE and TPR can be seen everywhere in daily life. The co-bonding effect of TPE, TPR and plastic depends on the difference in polarity between the two materials and the surface tension of the plastic. At present, the industry can provide mature technology TPE, TPR products, and most plastics such as ABS, PA, PC, PP, PS, PCTG, PBT and other good mutual adhesion (encapsulation).
(2) Co-bonding of TPR, TPE and metal and other materials
The co-adhesion of TPR and metal, this term is not so justified. Because TPE, TPR and metal bonding encapsulation, in most cases, not relying on the real bonding effect of the material, but using some special metal parts structure, or through the structural treatment of metal parts, through insert injection molding , The way of buckle coating, through physical and mechanical fixation, realizes the composite encapsulation of the two materials, rather than the literal co-adhesion. However, it is said that a small number of metal materials with higher surface chemical activity and TPE materials that have been polarized by functional groups can also be combined with materials under higher temperature conditions. This combination has a certain degree of firmness and does not rely solely on mechanical The embedding method has some co-adhesion effects.