What is the mechanism of zinc stearate in PVC processing?

Pre-stabilizer, inner and outer lubricants.

Well, thermal stabilization is the main effect, supplemented by lubricity.

Softening effect.

Molecular Formula: C36H70O4ZN Structural Formula: (C17H35COO)2ZN English abbreviation: ZNSt2

Uses: Mainly used as styrene resin, phenolic resin, amine resin lubricant and release agent. At the same time, it also has the function of vulcanizing active agent and softener in rubber.

It can be used as a non-toxic heat stabilizer for PVC, with good initial colorability and lubrication, no sulfur pollution, but the thermal stability is limited, and the zinc chloride formed has a catalytic degradation effect on PVC, which is generally not used alone, and is mostly used with calcium soap, barium soap and other stabilizers, mainly used for soft products.

In water-based coatings, it has the effect of increasing slippage and increasing sandability.

Accelerators that cannot be missing in foaming products.

The main uses and application fields of zinc stearate.

Stearic acid + sodium hydroxide = sodium stearate.

Sodium stearate + zinc chloride = zinc stearate.

There are mainly two processes:

The water method mainly refers to the metathesis method and the saponification method. The metathesis method uses stearic acid and sodium hydroxide to react, and then reacts with zinc salt to produce the precipitate of zinc stearate, and then separates and treats; The saponification method is to produce zinc hydroxide through the reaction of zinc salt and sodium hydroxide, and then react with stearic acid to produce zinc stearate, and then separate and process. It is characterized by the fact that products with good color and luster and high purity can be obtained, and the effect of use in specific industries is better than that of dry methods.

The disadvantages are low production efficiency, a large amount of water is consumed for cleaning, a large amount of salty wastewater is discharged, the drying energy consumption is large and the moisture is difficult to control, and the packaging bag is relatively large.

Dry method, mainly refers to the one-step method. The stearic acid is heated to a temperature above the melting point of zinc stearate, and then zinc oxide is put in, and the stirring reaction is carried out under the action of a catalyst, and the product is cooled and crushed to obtain zinc stearate of Hanwei new materials.

Production method.

There are two methods of producing zinc stearate: water method and melting method. Generally speaking, zinc stearate produced by the water method is acidic, and the melting method is alkaline.

The water method, also known as the wet method, adds a catalyst to control a certain temperature and pressure under the condition of water as the medium, and then adds metal hydroxides, and replaces the metal ions to the catalyst through the catalyst, and then replaces it to stearic acid through the catalyst itself, so as to achieve the purpose of generating metal salts. The catalyst is post-processed and recycled. Stearate is centrifuged, dried and ground to obtain products with an mesh count of 200-600 mesh that meets industry standards.

The water method usually produces a slight excess of stearic acid, so the finished product is acidic after the reaction.

The melting method, also known as the dry method, refers to the direct addition of metal oxide (indirect zinc oxide) to the molten stearic acid, (of course, under the condition of the presence of the catalyst, otherwise the conversion rate of the reaction will be very long) to control a certain temperature, pressure and stirring speed, and obtain stearate through the reaction. Due to the presence of catalysts, the general reaction results can be completely reacted, and the metal oxides are slightly excessive, so the products are alkaline when detected.

1. Stearic acid is used for internal lubrication and external lubrication in the process of PVC processing, mainly for internal lubrication.

2. When the amount of stearic acid is small, the frictional heat will increase, and the color of the product will be yellow, 3. When the amount of stearic acid is too much, the PVC product will be brittle, and the observation hole will be emitted.

The role of stearic acid in the processing and production process of rubber (tires).

Good morning, stearic acid generally plays the dual function of lubrication and plasticization in PVC and PP processing, and after adding, it will increase the surface smoothness and wear resistance coefficient of the extruded profile, please refer to it. In addition, the stearic acid will gradually melt during the heating process, and the low friction between the PVC melt and the extrusion pipe is always maintained, which is convenient for discharging.

Stearic acid is widely used in the manufacture of PVC plastic pipes, plates, profiles, and films. It is a PVC heat stabilizer, which has good lubricity and good light and heat stabilization. In plastic PVC pipes, stearic acid helps to prevent the processing of stearic acid"Coking"。

The addition of stearic acid can reduce the cohesion between polymer molecules, reduce its melt viscosity, and thus weaken the internal friction between polymers. Generally commonly used internal lubricants such as stearic acid and its salts, butyl stearate, stearamide, oleamide, etc.

Basically, zinc stearate is used in the initial plastic and rubber products, which mainly plays the role of heat stabilization, lubricant, filler and release agent in the raw plastics, and plays a high-temperature deinking agent and a softener to increase softness in rubber products due to its smoothness and thermal stability.

It is enough to add relevant auxiliary heat stabilizers, such as rational formulation. Add betadione, add liquid or powder, benzene-free, phenol-free, phosphite into it.

Auxiliary stabilizer is added. Polyols, hydrotalcite, etc., there are many in the books.