خلاصه ای از افزودنی های متداول اصلاح پلاستیک (2)

Foaming agent

دستگاه اکسترودر چینی foaming agent is used in polymer compounding system, which aims to obtain polymer products with microporous structure by releasing gas, and the auxiliary agent for the purpose of reducing the apparent density of products is called foaming agent. Depending on the way in which gas is generated during the foaming process, blowing agents can be divided into two main types: physical blowing agents and chemical blowing agents.

china extruder machine physical blowing agent generally releases gas by the change of its own physical state, mostly volatile liquid substances, chlorofluorocarbons (such as freon), low alkanes (such as pentane) and compressed gas are physical foaming agents represent.

Chemical foaming agents are foamed based on the gas released by chemical decomposition, and are divided into inorganic chemical foaming agents and organic chemical foaming agents according to different structures.

Inorganic foaming agents are mainly some heat-sensitive carbonates (such as sodium carbonate, ammonium bicarbonate, etc.), nitrites and borohydride compounds, etc., which are characterized by endothermic foaming process, also known as endothermic foam. Foaming agent.

Organic foaming agents have a very prominent position in the plastic foaming agent market, and the representative varieties are azo compounds, N-nitroso compounds and sulfonyl hydrazide compounds. The foaming process of the organic foaming agent is often accompanied by an exothermic reaction, and is also known as an exothermic foaming agent. In addition, some adjuvants that adjust the decomposition temperature of the blowing agent, that is, foaming aids, are also included in the list of blowing agents.

Antistatic agent

The function of the antistatic agent is to reduce the surface resistance of the polymer product and eliminate the electrostatic hazard that may be caused by the accumulation of static electricity. According to the different ways of use, antistatic agents can be divided into two types: internal addition type and coating type.

Internally added antistatic agent is added or blended into the plastic formula, and after molding, it migrates from the interior of the product to the surface or forms a conductive network, thereby reducing the surface resistance and discharging the charge.

Coated antistatic agents are attached to the surface of plastic products by coating or wetting, thereby absorbing moisture in the environment and forming an electrolyte layer that can discharge charges.

From the point of view of the composition of chemical substances, traditional antistatic agents belong to surfactant compounds almost without exception, including quaternary ammonium salt type cationic surfactants, alkyl sulfonate type anionic surfactants, alkanolamines, Nonionic surfactants such as alkanolamides and polyol fatty acid esters, etc.

However, the emerging “high molecular weight permanent antistatic agents” break this convention. They are generally hydrophilic block copolymers that cooperate with the base resin in the form of gold blends to conduct charges through the formation of conductive channels. Compared with surfactant-based antistatic agents, this high-molecular-weight permanent antistatic agent is not lost due to migration, volatilization and extraction, so its antistatic properties are lasting and stable, and it is less affected by ambient humidity.

Mildew inhibitor

As a manufacturer of plastic extruders, China جول uses antifungal agents, also known as microbial inhibitors, which are stabilizers that inhibit the growth of microorganisms such as mold and prevent polymer resins from being eroded and degraded by microorganisms. Most polymer materials are not sensitive to mold, but their products are susceptible to mold due to the addition of plasticizers, lubricants, fatty acid soaps and other substances that can breed mold during processing.

There are many chemical substances contained in the mold inhibitor for plastics. The more common varieties include organic metal compounds (such as organic mercury, organic tin, organic copper, organic arsenic, etc.), nitrogen-containing organic compounds, sulfur-containing organic compounds, halogen-containing organic compounds and phenolic derivatives.

Brightener

Optical brighteners are fluorescent dyes, or white dyes, which are also complex organic compounds. Its characteristic is that it can excite incident light to produce fluorescence, so that the dyed material obtains a sparkling effect similar to fluorite, and the material seen by the naked eye is very white.

Filler

The filling and reinforcement used by china extruder machine manufacturer is an important way to improve the physical and mechanical properties of plastic products and reduce the cost of compounding. The reinforcing materials involved in the plastics industry generally include fibrous materials such as glass fibers, carbon fibers, and metal whiskers. Filler is a bulk material with low compounding cost, including calcium carbonate, talc, terracotta, mica powder, silica, fly ash, red mud and natural minerals such as wood flour and cellulose, synthetic inorganic and industrial by-products.

In fact, it can be hard to tell the difference between reinforcing and filler, since almost all fillers have a reinforcing effect. Due to the large amount of fillers and reinforcing agents used in plastics, some of them have become an industry system of their own, which is not traditionally discussed in the category of processing aids.

It should be noted that the modification effect of nano-filled reinforcing materials widely studied by china extruder machine manufacturer on plastics has far exceeded the meaning of filling and reinforcing, and their application will bring a new revolution to the plastics industry.

Coupling agent is an interface modifier of inorganic and natural fillers and reinforcing materials. Since most of the reinforcing and filling materials in China’s plastic industry are inorganic materials, the compounding amount is large. When directly compounding with organic resins, it often leads to plastic compound processing and plasticity. Degradation of application performance. As a surface modifier, the coupling agent can make the surface of inorganic materials organic through chemical action or physical action, thereby increasing the compounding amount and improving the processing and application properties of the compound. The reported coupling agents generally include long carbon chain fatty acids, silane compounds, organic chromium compounds, titanate compounds, aluminate compounds, zirconate compounds, and anhydride-grafted polyolefins.

Cross-linking agent

The cross-linking of plastics is not fundamentally different from the vulcanization of rubber, but the use of cross-linking aids is not exactly the same. The cross-linking methods of resin mainly include radiation cross-linking and chemical cross-linking. Organic peroxide is the most widely used type of cross-linking agent in industry. Sometimes in order to improve the degree of crosslinking and the speed of crosslinking, it is often necessary to use some auxiliary crosslinking agents and crosslinking accelerators together.

The auxiliary crosslinking agent is used to inhibit the free radical cleavage reaction of the organic peroxide crosslinking agent on the main chain of the polymer resin during the crosslinking process, improve the crosslinking effect, and improve the performance of the crosslinked product. Its function is to stabilize polymer free radicals. The main function of the cross-linking accelerator is to speed up the cross-linking speed and shorten the cross-linking time. Curing agents for thermosetting plastics such as unsaturated polyesters and epoxy resins also belong to the category of crosslinking agents, common types such as organic amines and organic acid anhydrides. In addition, the photosensitizer used in the UV radiation crosslinking process can also be regarded as a crosslinking aid.

Dispersant

Plastic products are actually a mixture of basic resins and various pigments, fillers and additives. The degree of dispersion of pigments, fillers and additives in the resin is very important to the performance of plastic products.

Dispersant is an auxiliary agent that promotes the uniform dispersion of various auxiliary materials in resin, and is mostly used in masterbatch, colored products and high-filled products. Including hydrocarbons (paraffin oil, polyethylene wax, oxidized polyethylene wax, etc.), fatty acid soaps, fatty powder esters and fatty amides.

Lubricant

Lubricant is a processing modifier that is mixed in polymer resin to reduce the friction between resin particles, resin melt and processing equipment and intermolecular friction in resin melt, and improve its fluidity and mold release during molding. , It is mostly used in the processing and molding process of thermoplastics, including hydrocarbons (such as polyethylene wax, paraffin, etc.), fatty acids, fatty alcohols, fatty acid soaps, fatty acid esters and fatty amides.

Release agent

china extruder machine manufacturer mold release agents can be applied to the surface of molds or processing machines, and can also be added to the base resin to make the model products easy to demould and improve their surface finish. The former is called a coating-type release agent, which is the main part of the release agent, and the latter is an internal release agent, which has the characteristics of easy operation and so on. Silicone oil is the most widely used type of mold release agent in industry.