It is well known that various functional additives are indispensable in the process of film production. Slip masterbatch and anti-blocking masterbatch are two important additives.The function of the anti-blocking masterbatch is to prevent adhesion between films, especially for thin films or films with high surface gloss.
Traditional anti-blocking masterbatch is non-transferable inorganic minerals, such as diatomite, talc, kaolin, silica, and so on. The anti-blocking masterbatch can also play a small role in reducing the friction coefficient.
The function of slip masterbatch is to reduce the friction coefficient of the film surface and to ensure good subsequent processing, the common slip masterbatch is mainly oleic acid amide and erucic acid amide.
Now there are three kinds of anti-blocking addictive in common use: oleic acid amide, erucic acid amide, and silica. There are also some differences in the specific categories and usage methods. This paper mainly compares the difference between these three auxiliaries in slip and anti-blocking, to help people better make a proper choice between these two auxiliaries to meet the needs of production.
1. The introduction of anti-blocking and slip masterbatch
(1) Oleic acid amide
Oleate amide, also known as oleate amide; (Z)-9-18 acrylamide. The use of polyethylene film can reduce the internal friction between the film and the transmission equipment in the process of processing friction, and easy molding, thus increasing the yield, and improving the surface gloss of the product. Because of the low film addition (0.1-0.15%), the processing plant must add a mixture or masterbatch to ensure an even sliding effect.
In general, oleate amides migrate to the surface faster, but erucic amides have lower long-term friction resistance and better thermal stability than oleate amides.
It is mainly used as a slip masterbatch and anti-blocking masterbatch for CPP, BOPP, LDPE, LLDPE, EVA, PVC, PVDF, PVDC, PU, metallocene, and other plastics, which can significantly reduce the static and static friction resistance on the surface of the product (film or sheet) and improve the machinability and packaging efficiency.
(3) Main uses of silica:
1) Maintain the highlight of the film.
2) High specific surface area, strong anti-viscosity, especially suitable for thin film materials.
3) Good permeability, can be evenly dispersed in the resin, made of 10-25% anti-blocking masterbatch. Can be used for resin PP, PE, and other film products.
2. The development and effect of slip and anti-blocking masterbatch
The reason why the film is not easy to separate is that after the film is closed, there is a vacuum seal between the films, which is not easy to separate. The other is that after the film is formed, there are a lot of exposed molecular chains on the surface.
When the two membranes are closed, the chains of large molecules intertwine and cannot be opened. The membrane opening difficulty is due to the coexistence of both, with the latter being the main cause.
(1) History of anti-blocking masterbatch
The earliest anti-blocking masterbatch was inorganic light calcium powder and diatomite.
Oleic acid amide, erucic acid amide, erucic acid amide and EBS derivatives, etc.
At present, silica is also widely used as an anti-blocking masterbatch in thin films.
(2) The role of the anti-blocking masterbatch in different periods
The early inorganic anti-blocking masterbatch is to make the film surface is not uniform, reduce the membrane negative pressure separation;
The late organic anti-blocking masterbatch is to produce a lubricating film on the surface of the film, reducing the friction resistance of the film so that they do not adhere to each other.
(3) Side effects
Function additives usually have more or less side effects, mainly reflected in the film surface has a large amount of sediment, affecting the film printing, thermal sealing, and color.
If lubricants and organic thickeners are added to the formula, precipitates may be produced; Packaging pollution is very serious, especially in food packaging, liquid packaging, pharmaceutical packaging, and other fields.
3. Oleate amide, erucic amide, and silica performance differences
Slippery agent: Adding a sliding ingredient to a film is like adding a layer of water between two pieces of glass, you can easily roll the two pieces of glass, but it is difficult to separate the two pieces of glass.
Anti-blocking masterbatch: By adding an anti-blocking masterbatch or opening base material to the film, like roughing dry the surface between two pieces of glass with sandpaper, you can easily separate the two pieces of glass, but you can hardly roll the two pieces of glass.
Slip masterbatch: component amide (organic matter) transfer class.
(Note that at present, the main function of adding slip masterbatch to plastic films is to significantly reduce the friction resistance of the film and change the rolling property and anti-viscosity of the film.)
(1) Oleic acid amide
Low additive oleamide film (0.1-0.15%), must be added to the processing plant in the form of a mixture or masterbatch to ensure an even smooth effect. Oleate amide has a good effect on PE opening and precipitates quickly. The addition is low enough to meet the requirements, but it also has a fatal weakness. The taste settles quickly, affecting corona and printing. The temperature requirement is also very strict. Summer and winter doses are different. In addition, adding to the surface and core layers is also very important.
For example: to make the composite film transparent, such as a PP composite film with and PP friction coefficient below 0.4, must add lubricant (oleic acid amide or erucic acid amide), which generally should be added to the core layer (intermediate layer), so that it migrates to the surface.
(2) Erucerate amide
Erucic acid has strong smoothness, less precipitation, high-temperature resistance, is not easy to turn yellow, and has obvious advantages over oleic acid. For example BOPP as a new packaging material, its packaging rate is up to 500~800 packets per minute, and its friction coefficient must be ≤0.2, only adding erucic acid amide (0.12% or so), to obtain the static friction coefficient.
In addition to use alone, there are some examples: high smoothness requirements PP in the actual production process, erucic acid amide, and oleic acid amide mixed, to achieve the most ideal effect. For example, Genuine Plastic’s New Materials, a slip, and anti-blocking masterbatch manufacturer uses imported erucic and oleic amides, which have helped many companies reduce production costs.
(3)SiO2 anti-blocking masterbatch
SiO2 anti-blocking masterbatch can be evenly dispersed in the film, can produce a large number of fine and strong bumps on the surface of the film, and reduce the contact area between the film surface to reduce the friction resistance of the film surface, so that the film is easy to open, at the same time because of the existence of these prominent, make the external gas into the double film, avoid the vacuum between the film, avoid the film adhesion.
4. How to choose the right additives?
In slip and anti-blocking masterbatch, the choice of amide and silica is very important for the performance of masterbatch.
Because the quality of the amide is not uniform, the quality of the additives is poor, which will make the masterbatch film, film taste, like there are black spots on the film. These are caused by excessive impurities in animal oil. Therefore, the selection and use should be determined according to the performance and application of amide.
The selection of silica is more important, the particle size, specific surface area, water content, surface treatment, etc., have an important impact on the masterbatch production and film production process.