Silica anti-block agent, an essential additive for films

Silica anti-block agent, an essential additive for films

Wednesday, 11 February, 2026

An anti-block additive is a substance in the form of fine particles. It is added to plastic materials, especially thin films such as those used in packaging, in order to prevent them from sticking to each other during manufacturing, stacking or winding.

The anti-block additive is incorporated into the film during the extrusion process by means of an additive concentrate, also referred to as a masterbatch. This concentrate, in which the anti-block particles are pre-dispersed in a polymer, facilitates uniform distribution of the additive throughout the film.

Figure 1. Examples of films and packaging incorporating anti-block additives to improve processing.

Comindex offers the extensive range of HOMBLOC® anti-block additives, based on synthetic silica, from the manufacturer LINGWE. HOMBLOC® significantly reduces the coefficient of friction of the film surface thanks to its unique technology, resulting in smoother downstream production processes and improved overall production efficiency and film quality. This synthetic silica offers numerous advantages when used as an anti-block additive:

High anti-blocking efficiency
Excellent compatibility with all types of polymers
Maintained transparency
Non-toxic and safe
Thermal and chemical stability
Enhanced production performance
Durability and slip resistance

Depending on the final application, we recommend the following grades:

Polyester (PET) film:HOMBLOC™ prevents adhesion between film layers during the production process by controlling the surface microstructure, effectively maintaining the original optical properties of the film while preventing blocking.

Recommended grades:
- Optical film: CTT300
- Matt film: CTT320, K35, K45

Polypropylene (PP) film:HOMBLOC™ facilitates masterbatch production thanks to its controlled surface modification characteristics, porosity and narrow particle size distribution. Its unique porosity significantly reduces the coefficient of friction of the film surface, resulting in smoother downstream processing, improved overall efficiency and enhanced film quality.

Recommended grades:

Film CPP: K35, K45, K45N
Film BOPP: K25, K35, K45, K45N

Polyethylene (PE) film :HOMBLOC™ offers a purity of up to 99%, meeting the requirements for high-concentration masterbatch formulations. By controlling particle size distribution, the service life of the extruder filter is effectively extended.

Recommended grades: K50N, K70, K80

A summary of the main characteristics of these grades can be found in the following chart:

Figure 2. Different grades of HOMBLOC® synthetic silica according to particle size and porosity. Source: Lingwe catalogue.

Within the wide range of HOMBLOC® silicas, we can recommend the anti-block additive best suited to your requirements and those of your customers.

At Comindex we can support you throughout your process. Simply contact our team of technical sales advisors.

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