cast film manufacturing

cast film manufacturing

Substances that reduce friction and wear between surfaces are called slip agent. Plastic molding processing, can increase the flow of materials or improve the release effect of molding parts of the material is also called slip masterbatch. Broadly speaking, film slip masterbatch, anti-blocking masterbatch (or opening agent), slip masterbatch of injected products, gloss agent, etc., also belong to the category of slip masterbatch.

With the resin, compatibility is poor, between the surface of the processing machinery and the resin plays the role of lubrication layer, said outside the slip masterbatch, with the resin good compatibility, can reduce the melt viscosity of the resin, improve the fluidity of the said inside the slip masterbatch.

1. The role of slip masterbatch in plastic processing

Thermoplastics are generally high molecular weight substances, and their melts are usually highly viscous. Because the molten polymer must pass through a narrow slit, runner, or extrusion die head in the shortest possible time, all thermoplastics are virtually processed in the molten state and under shearing.

(1) Slip masterbatch can reduce machine wear

To increase production capacity with minimal mechanical wear and energy consumption, it is important to minimize melt viscosity. This can be achieved in two ways: first, the maximum processing temperature that the material can bear; Second, add function additives that can reduce internal friction and external friction, namely, slip masterbatch.

There is a limit to the allowable temperature rise at a given shear rate. Any higher, and the polymer’s long-chain molecules break, reducing the viscosity of the melt and making the depolymerized material lose its strength. Despite the presence of stabilizers, high thermal stress can also lead to molecular degradation, the formation of unwanted reaction products, severe discoloration, and even carbonization. A well-known example is the thermal degradation of PVC due to dehydrochlorination. The only way to solve this problem is to use it effectively.

(2) Slip masterbatch can improve melt fluidity

Slip masterbatch is an additive to promote plastic processing by improving melt fluidity and reducing melt adhesion to machine parts. In addition to this function, the slip masterbatch can also play the role of a melting accelerator, anti-adhesion agent, and anti-static masterbatch, as well as color and impact improver.

Slip masterbatch is mainly organic compounds, some are natural products, such as petroleum, animal and plant oils, and wax; Some are synthetic products, such as low molecular weight polyethylene. In its application form, mainly free-flowing and non-coalesce solid particles, the upper melting point is about 150℃, but liquid products can also be used, while paste products are difficult to operate and not used.

2. Technical application of slip masterbatch

The relationship between slicks and plastics can be compared to electrical systems and cars.

(1) Film production is inseparable from the slip masterbatch

Although the slip masterbatch is an accessory on the surface, it is impossible to realize the industrial production of PP film and PE film without the slip masterbatch, just like the car cannot run without the electrical system. Other thermoplastics that can be processed without slip masterbatches, such as polyethylene or polypropylene, are increasingly required to use these additives to solve the productivity problem. The use of slip masterbatch in specialty plastics is of some importance, though it may not seem obvious.

(2) Slip masterbatch promotes product updating

Slip masterbatches are used not only to improve fluidity and productivity (which make them an irreplaceable aid) but also to obtain high-quality products, especially those with a high appearance. This is important from both an aesthetic and a technical point of view. For example, household products and packaging films require gloss and smoothness, and bottles and pipes are protected from rough inner surfaces.

In the past decade, the development and application of high-performance calendering machines, blow and injection molding machines, extruders, and other plastic processing equipment have been successful precisely through the simultaneous development of a special slip masterbatch.

(3) The amount of slip masterbatch added

Slip masterbatch can be used as blown film masterbatch or cast film masterbatch.

Because the concentration of the slip masterbatch in plastics is relatively low, it is also called “functional masterbatch”. The mass fraction of the slip masterbatch in plastics generally ranges from 0.01% to 4.0%, but the actual amount depends on the type of plastic. For processing equipment and final products, the actual industrial usage range is 0.5% to 1.0%.