Why are these three openers most commonly used in the film industry? How should slippery agent and opening agent distinguish use?
There are three kinds of commonly used anti-adhesion agents: oleic acid amide, erucic acid amide, silica. There are also some differences in specific categories and methods of use. This paper mainly compares the difference between these three additives in opening smooth and anti-adhesion.
A brief introduction of the opening lubricant
1. Oleate amide
Oleic acid amide, also known as oleic amide; (Z) -9-octadecenoamide. Using it in polyethylene film can reduce internal friction in the process of processing between film and transmission equipment friction, easy demoulding, thereby increasing the yield, improve the surface gloss of products. (Due to the low amount in the film (0.1-0.15%), it must be added in the form of mixture or masterbatch in the processing plant to ensure a uniform smooth effect.)
Oleic acid amide is also called oleic acid amide; (Z) -9-octadecenoamide
Molecular formula: C18H35NO
Molecular weight: 281.48
In general, oleate amide migrates to the surface faster, but erucic amide has a lower long-term friction coefficient than oleate amide and better thermal stability than oleate amide.
2. Erucamide
Mainly used as CPP, BOPP, LDPE, LLDPE, EVA, PVC, PVDF, PVDC, PU and metallocene plastic slippery agent and anti-stick agent, can significantly reduce the dynamic and static friction coefficient of products (film or sheet) surface, improve workability and packaging efficiency.
3. Silica
Main uses:
1) Maintain the high gloss of the film.
2) With high specific surface area, strong adhesion resistance, very suitable for film materials as an opening agent.
3) Good dispersion, can be very evenly dispersed in the resin, made of 10-25% anti-adhesion masterbatch. Can be used for PP,
PE and other film products.
Two, the development and role of opening agent
The reason why the film is not easy to separate is that the vacuum close state is formed between the films after the film is closed, which is not easy to separate; The other is that there are a large number of exposed molecular chains on the surface of the film after it is formed, and entanglement between the large molecular chains occurs after the two films are closed, making it impossible to open. In fact, the cause of membrane opening difficulty is the coexistence of both, and the latter is the main reason.
1. History of opening agent
The earliest opening agent is inorganic talc, diatomite, etc.
Middle development to organic oleic acid amide, erucic acid amide and EBS derivatives;
At present, synthetic silica is also widely used in thin films as an opening agent.
2. Action of the opening agent in different periods
Early inorganic opening agent is to make the surface of the film uneven to reduce the negative pressure membrane separation;
Later organic opening agent is to form a layer of lubrication film on the surface of the film, reduce the friction coefficient of the film, so that it does not adhere to each other.
3. The side effects
Additives generally have different degrees of side effects, mainly manifested in the organic opening agent has a large number of precipitates on the surface of the film, affecting the film printing, heat sealing and color. If lubricant and organic dispersant are added to the formula, precipitates may be produced. The pollution of the packaging is very serious, especially in food packaging, liquid packaging, drug packaging and other fields.
Three, oleic acid amide, erucic acid amide and silicon dioxide performance difference
Slippery agent: Adding a slippery agent to a film is like adding a layer of water between two pieces of glass. You can slide the two pieces of glass easily, but it's hard to pull them apart.
Openers: Adding openers or openers to a film is like roughing the surface between two pieces of glass with sandpaper. You can easily separate the two pieces of glass, but you can't slide them.
Open masterbatch: the composition is silica (inorganic) does not migrate.
Smooth masterbatch: amide (organic matter) migration type.
(Note: at present, the main function of adding skid agent in plastic film is to change the sliding property and anti-viscosity of the film by significantly reducing the friction coefficient of the film.)
1. Oleate amide
Oleate amide film in low amount (0.1-0.15%), in the processing plant must be added in the form of mixture or masterbatch, in order to ensure uniform smooth effect. Oleate amide on PE opening effect is good precipitation fast, very low amount can meet the requirements, but it also has fatal weakness, taste big precipitation fast, resulting in the impact of corona and printing, for the temperature requirements are more strict, in summer and winter dosage is different, in addition to add in the surface layer and core layer is also very exquisite.
Such as: the composite film (such as transparent PP composite film and PP pearlescent film, etc.) friction coefficient is lower than 0.4, must be added to the smooth agent (oleic acid amide or erucic acid amide), generally should be added to the core layer (intermediate layer), so that it migrated to the surface.
2. Erucamide
Erucic acid has strong smoothness, less precipitation, high temperature resistance, not easy to turn yellow, compared with oleic acid has obvious advantages.
Such as: BOPP as a new type of packaging material, its packaging speed up to 500 ~ 800 packages per minute, its friction coefficient must be less than or equal to 0.2, only add erucic acid amide (0.12% or so), to obtain static and dynamic friction coefficient.
In addition to the use alone, there are such as: PP blowing film requirements for smoothness is very high, in the actual production process is used erucic acid amide and oleic acid amide mixture used together, so as to achieve the most ideal effect.
3.SiO2 anti-adhesion agent
Agent SiO2 antiblocking (opening) can be spread evenly in the film, can in the thin film surface to form a number of fine and hard protuberant, thus reducing the contact area between the thin film, realized the purpose of reduce the film surface friction coefficient, the film is easy to speak, at the same time due to the presence of these processes, the outside air to enter between the two layers of thin film, To prevent the formation of a vacuum between two layers of film, so as to prevent film adhesion.
Four, how to choose the right additives?
The choice of amides and silica is very important to the properties of the open smooth masterbatch.
Because the quality of amide is uneven, the poor quality of the additives, will make the masterbatch film, film taste, film has black spots. These are caused by excessive impurities in animal oil. Therefore, in the selection of use process, should be based on the performance and use of amide and decided.
The selection of silica is more important, particle size, specific surface area, water content, surface treatment, etc., have an important impact on the production of masterbatch and film production process.
(Note: The opening is not good, how to do? General technical people want to add master material, but the real technical people, will consider other methods, is the process, such as cooling temperature, etc., are related.
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