How to choose right release agent in the production of plastics and thermoplastic elastomers?

How to choose right release agent in the production of plastics and thermoplastic elastomers?

Original/Meite polymer zhongming

  • What are anti-blocking agents?
  • Debonding agent, also known as anti-slip agent, release agent, anti-caking agent, etc., is often used in production and preparation of materials for plastic film, which can effectively improve opening performance of film. The earliest release agents were inorganic talc, diatomaceous earth, etc.; in medium term, organic oleic acid amide, erucamide and EBS derivatives have been developed; At present, synthetic silica is widely used as a release agent in thin films.

  • Types and properties of antiblocking agents
  • There are three generations of release agents for plastic films: first generation is talc, diatomaceous earth, calcium hydrogen phosphate, etc. and other physical and chemical properties of plastic films. The second generation is oleic acid amide, erucic acid amide and ethylene-bis-stearamide (EBS) derivatives, etc. The disadvantage is that organic release agent precipitates attach to film surface, which worsens printing properties and heat resistance. tightness and color of film affect its safety as a food packaging material. The third generation is synthetic silica, which has advantages of good opening performance and non-toxicity. Adding it can also increase tensile strength and elongation at break of plastic film, so that performance and physical properties of plastic film can be improved. improved, and plastic film can be reduced. The production cost of thin film is currently most widely used, and it is main product at home and abroad.

  • How anti-blocking agents work
  • How to choose right release agent in the production of plastics and thermoplastic elastomers?

    Figure 1. The principle of operation of anti-adhesive microparticles

    How to choose right release agent in the production of plastics and thermoplastic elastomers?

    Figure 2. How osmotic opening agent works

    There are two main reasons why plastic films stick together: first is that vacuum seal between films is not easy to separate after film is closed; second is that after film formation, a large number of open molecular chains remain on surface of two films. Once closed, entanglement between macromolecular chains makes it impossible to open. In fact, reason for difficulties in opening film is that they coexist, and latter is main reason. The early inorganic release agent should make surface of film uneven, so as to reduce negative pressure between films and separate them. The working principle is shown in Figure 1. The later organic release agent should form a layer of lubricating film on surface of film to reduce coefficient of friction of film so that it does not stick to each other. friend The principle of operation is shown in Figure 2. Both also prevent entanglement of molecular chains. The principle of operation of new anti-slip agent is to use nano-sized silica powder to disperse micron-sized particles in resin. This particle is formed due to aggregation energy of silica itself without addition of any auxiliary substances. This particle is porous, uneven, soft, with a large specific surface area, 1–2 μm in diameter and a specific surface area of ​​500–600 sq. m. meters per gram, end of macromolecular chain of polymer is absorbed by gap of silica particle during processing, and at same time becomes nucleation center for particle crystallization. Thus, open molecular chains are greatly reduced, and problem of opening is solved when two films are in contact. At same time, unopened film of molecular chains also reduces adsorption force of rubbing objects, thereby increasing slipperiness. Such particles not only protrude surface of film, but also perform function of sealing ends of macromolecular chains. During processing of polymer, ends of macromolecules are absorbed by pores of particle, and particle can become a nucleation site to accelerate crystallization rate of polymer. In this way, open molecular chains are significantly reduced so that entanglement of macromolecular chains does not occur when two membranes touch and the hole problem is solved.

  • Effect of blocking agent on appearance and performance of TPE
  • How to choose right release agent in the production of plastics and thermoplastic elastomers?

    Figure 3. Visualization of surface of material

    As shown in Figure 3, surface roughness of an elastomer with addition of a release agent is high. This is because a solid release agent powder is added to elastomer to form a plurality of protrusions on surface. plastic, so actual distance between layers of plastic. The contact area is reduced, which reduces adhesion. From Figure 2, it can be seen that extrusion gloss of samples is expressed as matte, but extrusion spline of sample + erucamide is thinner, main reason is that particle size of erucamide is small, and protrusion is caused by blocking agent. relatively small. The surface of sample with addition of silica is more matte, since purpose of addition of silica is to roughen surface of material, create concave and convex points, and prevent film-to-film adhesion. As a result, roughening will inevitably affect surface and optical properties of material.

    How to choose right release agent in the production of plastics and thermoplastic elastomers?

    Table 1. Filler/TEP ratio is 10/90, TPE mechanical properties data

    This can be seen from table 1: compared to a blank sample. The strength of sample + erucamide, sample + silica decreased, and strength of sample + behenamide increased significantly, but tensile properties of three samples significantly decreased, indicating that addition of above-mentioned anti-blocking compound had a positive effect. great influence on mechanical properties of sample, a noticeable effect on performance. This is due to fact that, on one hand, inorganic components of compound release agent are dispersed in elastomeric plastic in form of small solid particles. Due to uneven distribution, agglomeration of release agent causes certain defects, which leads to a decrease in elongation at break. On other hand, particles play role of a product nucleus, which improves crystallization characteristics of plastic part in elastomer, thereby increasing strength of material, and strength and elongation at break of sample + behenamide are greatly increased. .

    So, on surface of material, choice of erucamide release agent can make surface of material more delicate, and silicon dioxide and behenamide release agent can make material more matte; In terms of mechanical properties of behenyl-added material, mechanical properties of material obtained with amide release agent are better, while mechanical properties of material obtained with silica and behenamide release agent are relatively poor. You can choose appropriate anti-blocking agent according to your needs.

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