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It is said that the film processing to use the six kinds of additives, you know?

2016-9-19 11:21:37

Some resin film products or its inherent performance do not meet the required processing requirements, the need to add additives to change its processing; some other material processing performance is good, but the product performance can not meet the requirements, should also add additives to change its product performance.
Requirements of films for additives
Compatibility
Compatibility is not good, will lead to "migration" phenomenon, performance in the liquid additives for "sweating", in the performance of the solid additives for "spray cream"".
Sometimes in the not too strict on the film, allowing the lack of compatibility, such as fillers and resin compatibility is not good. As long as the size of the filler is small, still can meet the basic requirements of the performance of the film, if the coupling agent or surfactant treatment, then can better play its function. But there are some additives for improving the surface properties of the film, such as opening agent, antistatic agent, it is required to have a little mobility, so as to make it play a role in the surface of the film.
Durability
It is required that the additives are present in the thin film for a long time, but the loss of the additives is mainly through three ways: volatilization, extraction and migration. This is mainly related to the molecular weight of the promoter, the solubility in the medium and the solubility in the resin.
Processing conditions
Some resin processing conditions are harsh, such as high processing temperature, the ion of additives should be considered whether the decomposition of additives on the processing equipment, there is no corrosive effect.
Film use
Different uses of the film on the smell, toxicity, weather resistance, thermal properties, etc. have different requirements. For example, plastic bags containing food, due to the requirements of non-toxic, so the additives used in general packaging with plastic bags of additives is different.
Synergistic effect and phase resistance of auxiliary agents
In the same resin system, some of the two additives will produce a synergistic effect ". If a mismatch, may lead to "anti phase effect" of some additives, it will weaken the function of each agent, or even lose its effect, such as carbon black and phenolic antioxidants and will produce antagonism.
Auxiliary agent capable of changing film packaging performance
Plasticizer and heat stabilizer
Plasticizer and heat stabilizer can greatly improve the compatibility of thin film materials.
Plasticizer, as the name suggests is to increase the plasticity of the material, on the one hand, the resin in the molding process of increasing liquidity, improve the processing performance, on the other hand, can be made after the film flexibility and flexibility to increase the material.
Heat stabilizer is mainly to improve the thermal stability of the resin.
Light stabilizer
Polymer materials in the sun and the light and the high-energy X-ray irradiation, rapid aging, performance and electrical properties of yellow, brittle, surface cracking, lose luster, machinery is greatly reduced, or even lost their use value. In this complex process of destruction, UV is the main reason for the aging of polymer materials. It is mainly the result of the combination of the ultraviolet and the oxygen in the atmosphere.
Effect of light stabilizer:
Effective absorption wavelength of 290~410nm ultraviolet light, to eliminate or weaken ultraviolet protection from ultraviolet radiation and oxygen polymer film damage, prolong the service life, improve the light fastness of materials. Because most of the light stabilizer can absorb the ultraviolet light, the light stabilizer is also called the UV absorber.
Additive amount of light stabilizer:
According to the action mechanism of light stabilizer, it can be divided into: light shielding agent (pigment), ultraviolet absorbent, ultraviolet quenching agent, free radical trapping agent. These four modes of action constitute the four levels of the gradual deepening of the light stabilization.
After adding light stabilizer, although the amount is very small, the effect of preventing aging is very significant, generally only need to add the weight of the polymer 0.1%~0.5%.
Antioxidant
For most varieties of plastic, in the manufacture, processing, storage and application process, have a certain sensitivity to oxidative degradation, oxygen into the plastic film and almost most polymers can react to degradation or crosslinking, thus changing the properties of materials. A small amount of oxygen can make the strength, appearance and performance of the polymer materials change dramatically. Under heat and sunlight, the oxidation rate is much faster. As a result, the oxidation of the polymer is generally divided into thermal oxidation and photo oxidation. At the end of the reaction, the result of this kind of reaction is the aging of the performance. This kind of reaction, if not blocked, can quickly make the polymer oxidation and lose the value.
The stability of different plastics for oxygen is different, so some plastic without adding antioxidants. Others must be added antioxidants, antioxidant activity is to capture free radicals, the chain reaction is interrupted, the purpose is the oxidation process and slow the pace of plastics.
In general, the protective effect of phenolic amine antioxidants than high, but because by amines in light and oxygen under the action of different degrees of change, does not apply to light brilliant color and transparent film, so it is less used in plastic film.
In accordance with the antioxidant effect, will be divided into the main and auxiliary antioxidant antioxidant antioxidant. The aerobic effect of aniline is better, but the pollution is bigger, mainly used in rubber products. The effect of phenolic antioxidant is slightly worse, but the pollution is small, and the comprehensive effect is better. Usually, thiol or thioester phosphite under the auxiliary antioxidant, and main antioxidant and use, to produce a synergistic effect, extend the antioxidant efficiency.
Lubricant
Polymers usually have higher viscosity in melting, in the machining process, the molten polymer in through the slit, the gate and runner, the polymer melt must cause friction with the friction surface processing machinery, reduce the melt flow at the same time, serious friction will cause the film surface becomes rough, the lack of luster or rhyolite. To this end, it is needed to add to improve the lubrication, reduce friction, and reduce the adhesion property of the interface.
In addition to improving the flow of lubricant, but also can play a melting agent, anti adhesion and anti - static agent, cool agent, etc..
External lubricant is mainly to improve the polymer melt and the processing equipment of hot metal surface friction, it has poor compatibility with polymer, easy to melt from the inside out migration, so thin can form the lubrication in the plastic melt and metal interface.
Internal lubricant and polymer has good compatibility, it is to reduce the polymer intermolecular cohesion role in polymer, so as to improve the fluidity of plastic melt in friction and melt.
Actual every kind of lubricant has the function that can realize a certain requirements, always the internal and external lubrication interaction, but in a more prominent. The same kind of lubricant in different polymers or different processing conditions will show different lubrication, such as high temperature, high pressure, the internal lubricant will be squeezed out and become an external lubricant.
In the production of plastic film, we will encounter some adhesion phenomenon, such as in the production of plastic film, the two layer of film is not easy to separate, which brings difficulties to automatic high-speed packaging. In order to overcome it, add a small amount of additive to the resin to increase the surface lubrication, to increase the external lubrication, commonly known as anti adhesion agent or smooth agent. In the molecular structure of general lubricant, there are two parts of the non polar and polar groups, which are different in different polymers.
In the extrusion molding, the mobility can be improved, the adhesion of the polymer material and the barrel and the mold can be improved, and the retention of the retention material can be prevented and reduced. In addition to improve the appearance and gloss of the film. The amount of lubricant is generally in the 0.5%~1%.
Attention should be paid to the ion:
1. The flow properties of the polymer have satisfied the need of the molding process, which mainly consider the effect of external lubrication to ensure the internal and external balance;
2, external lubrication is effective, whether it should be in the molding temperature, the plastic surface layer to form liquid film complete prevail, so the external lubricant should be close to the melting point and molding temperature, but the difference of 10 DEG ~30 DEG to form a complete film;
3, the surface gravity is small, the viscosity is small, the expansion of the interface is good, easy to form the interface layer;
4, their heat resistance and chemical stability, not in the processing of decomposition, non-volatile; non corrosive equipment, non polluting films, no toxicity.
Use characteristics of different types of lubricants:
Use of natural wax for external lubrication, can be used as a variety of plastic lubricants, release agents, the general amount of 0.2~1phr, but the compatibility, thermal stability and dispersion is not very good, the amount is not too large, and the best lubricant and use; and use the inner lubricant oil PVC, PS, good lubricating performance thermal stability is also very good, the general amount of 0.5phr. They are non-toxic, can be used for food packaging. Another kind of microcrystalline wax: it is also used as a lubricant in the plastic processing, the amount of 1~2Phr, thermal stability and lubrication is better than ordinary paraffin. Low molecular weight polymers are also widely used as lubricants, such as polyethylene wax, low molecular weight polypropylene, the internal and external lubrication is good, and non-toxic. Polyethylene wax for PVC materials such as extrusion, rolling processing, the amount is generally 0.1~1phr, can improve the processing efficiency, prevent film adhesion, improve the dispersibility of pigments or fillers, compatibility and transparency is not very good.
Anti fog agent
Transparent plastic film, sheet or plate, in the humid environment, when the humidity reaches below the dew point, a layer of fine water lets condense on the surface, the surface of fuzzy atomization, light through the obstacle, such as the use of film packaging products, also because of fog and invisible contents, and the fog is also likely to cause the contents of decay damage.
Classification of fog:
In addition type antifogging agent is added to the resin in the ingredients, which is not easy to loss, lasting effectiveness, but for the high crystallinity polymer to obtain good antifogging property;
Coated with anti fog agent is soluble in organic solvents or water, surface coated on plastic film, and easy to use, low cost, but poor durability, easy to be washed or erased, and only use type anti fogging agent invalid or does not require persistence.
Anti fogging agent effectiveness can be divided into Anti Fog and lasting anti fog and low temperature and high temperature anti fog anti fog for the four stage, a anti fog hard to combine four kinds of effects, often according to the requirements of the anti fog film, with the use of several.
The anti fog agent should have the following properties:
1, anti fog efficiency, effective rapid, good durability;
2, good thermal stability, thermal decomposition is not easy, and the decomposition of the polymer does not lead to the degradation of polymers;
3, and other additives with good coordination, does not interfere with the function of other additives;
4, does not affect the transparency of the film, electrical properties, adhesion, resistance to pollution and other functions.
Several typical anti fog agent:
Glycerol monooleate white wax, with added anti fog agent, has good initial anti fog and low temperature anti fogging, suitable for food packaging film, general dosage in polyethylene was 1~1.5, polyolefin is 0.5~1.
Span-40 yellow granular material, as with anti fog agent, quick effect lasting, is added in the anti fog agent, it is yellow granular solids, the melting point of about 60 DEG C, lasting effectiveness, commonly used in agricultural film, also can be used as food packaging materials, in which poly vinyl chloride the dosage is generally 1.5~1.8, the polyvinyl acetate is 0.7~1.
Poly ethylene oxide (20) glycerol mono stearate is also an internal plus anti fog agent, effective fast, with a good early and low temperature anti fog. It is a light yellow liquid, but also has the anti-static effect, suitable for food packaging film.

Bottle blowing machineProfessional manufacturerASNTO|SNTO|Xintai bottle blowing machineHuangyan Zhejiang Plastic Machinery Factory

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