English
In-Depth Analysis of Opening Agent Silica Dioxide Technology: Evonik’s Full-Spectrum Silica Antiblocking Solutions Drive Quality & Efficiency for the Global Film Industry
Created on 11.03
In-Depth Analysis of Opening Agent Silica Dioxide Technology: Evonik's Full-Spectrum Silica Antiblocking Solutions Drive Quality & Efficiency for the Global Film Industry
Based on TI 1206 Technical Guide: Complete Breakdown of Working Mechanisms, Product Portfolio, Processing Applications and Global Compliance for Synthetic Silica Opening Agents
Against the backdrop of the global plastic film industry’s upgrade toward high clarity, high efficiency and food-grade safety, inter-layer film blocking remains a core industry pain point restricting production efficiency and finished product quality. As a core functional additive to solve this challenge, opening agent silica dioxide has gradually replaced traditional talc and organic amide-based opening agents and become a standard raw material for high-end film manufacturing, thanks to its high antiblocking efficiency, excellent optical compatibility and reliable safety performance.
Recently, Evonik, a global leader in specialty chemicals, released its technical whitepaper Silica as Antiblocking Agent in Plastic Films (TI 1206). As the only global manufacturer with mass production capacity for both precipitated and fumed silica antiblocking products, Evonik systematically presents the working principle of silica opening agents, performance evaluation standards, full-range product specifications and scenario-based application solutions, providing complete technical reference and product selection guidance for the global film manufacturing industry.
1. Film Blocking Pain Points Drive Material Upgrade, Opening Agent Silica Dioxide Emerges as the Industry's Optimal Solution
Film blocking refers to the adhesion between two adjacent film layers during winding and storage, caused by strong van der Waals forces and electrostatic charging. High temperature and pressure during processing and storage further intensify blocking strength. This problem directly leads to unsmooth film winding, reduced slitting efficiency, and higher scrap rates in downstream bag-making and printing processes; in severe cases, it can cause entire film rolls to be scrapped, making it a key difficulty for waste control in film production enterprises.
Among traditional solutions, natural mineral opening agents such as talc and diatomaceous earth have drawbacks including wide particle size distribution, poor transparency and equipment abrasion. Organic amide slip agents carry migration and precipitation risks, which easily affect film printing adhesion and heat sealing performance, and pose safety hazards in food and pharmaceutical contact scenarios.
In comparison, opening agent silica dioxide (synthetic silica opening agent) achieves antiblocking effects through a physical micro-isolation mechanism, with core advantages including high purity, controllable particle size, low optical impact and no migration risk, making it the most widely used antiblocking solution in the high-end film sector today. Its core working principle is as follows: micron-sized silica particles are uniformly dispersed into the polymer matrix; after extrusion into film, the particles form uniform micro-protrusions on the film surface, acting as physical spacers to greatly reduce the effective contact area between film layers and weaken van der Waals forces and vacuum adsorption effects from the root. At the same time, it reduces the friction coefficient between film layers, ensures smooth winding, slitting and downstream processing, and does not cause significant negative impact on film transparency, gloss and mechanical properties.
2. From Mechanism to Quantification: Building a Standardized Antiblocking Performance Evaluation System
Scientific performance testing is the core basis for verifying opening agent effectiveness. Currently, two evaluation methods are commonly used in the industry to quantify the antiblocking performance of opening agent silica dioxide from different dimensions, forming a complete industrial-grade evaluation system.
2.1 Coefficient of Friction (COF) Test: The Mainstream Industry Evaluation Method
Coefficient of Friction (COF) testing is the standard method for evaluating antiblocking performance in the global film industry, featuring simple operation and good repeatability, and can accurately distinguish performance differences between different opening agents.
During the test, two film specimens are pressed together under a defined weight, one specimen is then slid at a constant speed in the horizontal direction, and the frictional resistance during sliding is recorded. The ratio of frictional resistance to pressing weight is the coefficient of friction. This indicator directly reflects winding smoothness during film production and operability in subsequent processing — static friction coefficient corresponds to starting resistance, and dynamic friction coefficient corresponds to continuous sliding resistance; the lower the value, the better the antiblocking and slip performance.
2.2 Blocking Force Test: Simulating Real-World Storage Scenarios
The blocking force test is closer to the actual storage state of films: specimens are first preconditioned by pressing together for a set time under specified temperature and pressure, then the maximum force required to separate the two film layers is measured via vertical tension. This method can intuitively simulate long-term blocking risks in high-temperature storage environments, but due to complex testing procedures and weak result repeatability, it is usually used as a supplementary verification method to the friction coefficient test.
3. Full Product Portfolio: Four Series Covering Full-Spectrum Film Application Scenarios
Evonik is the only global manufacturer offering both precipitated and fumed silica opening agents, with four product lines: SIPERNAT®, SPHERILEX®, AEROSIL® and AERODISP®, covering all application scenarios from ordinary packaging films to high-end optical films, and providing precisely matched opening agent silica dioxide solutions for films of different substrates and thicknesses.
3.1 SPHERILEX® Spherical Precipitated Silica: Optimal Balance of High Clarity and High Antiblocking Efficiency
The SPHERILEX® series represents Evonik's innovative precipitation process, featuring near-ideal spherical particle morphology and extremely narrow particle size distribution, as well as high tamped density and low oil absorption properties. It is a benchmark opening agent silica dioxide product in the high-end transparent film sector.
The series includes two core grades:
- SPHERILEX® 30 AB
- SPHERILEX® 60 AB
Benefiting from its low specific surface area and low oil absorption structure, the SPHERILEX® series has extremely weak adsorption on amide slip agents. When used in combination, it ensures effective precipitation of slip agents and achieves synergistic "antiblocking + slip" performance. Actual test data shows that in 25 μm PE blown film with slip agent added, SPHERILEX® products deliver significantly better balance of haze and friction coefficient than traditional precipitated silica and silica gel competitors.
3.2 SIPERNAT® Precipitated Silica-Based Products: Graded Adaptation for Full-Thickness Film Scenarios
The SIPERNAT® series is Evonik’s longest-applied and most market-proven opening agent silica dioxide product line, covering diverse demands from high-clarity films to medium-thick industrial films, with mature application foundation and high cost performance.
- SIPERNAT® 44 MS
- SIPERNAT® 310
- SIPERNAT® 500 LS
Evonik provides clear product selection guidance for different polymer systems and film types: high-clarity PE films prioritize SPHERILEX® 30 AB and SIPERNAT® 44 MS; standard PE films are compatible with SPHERILEX® 60 AB and SIPERNAT® 310; biaxially oriented films such as BOPP and BOPET recommend SPHERILEX® 30 AB; PET and PA films are compatible with the full SPHERILEX® series; PVC calendered films can use SPHERILEX® 60 AB and SIPERNAT® 310/500 LS.
3.3 AEROSIL® Fumed Silica & AERODISP® Dispersions: Performance Ceiling for Ultra High-End Scenarios
For scenarios with extreme requirements for transparency and purity, such as optical-grade films, electronic-grade films and ultra-thin biaxially oriented films, Evonik offers the AEROSIL® fumed silica series of opening agent silica dioxide products.
Fumed silica particles can reach submicron scale; when uniformly dispersed, their impact on film transparency is minimized, and they feature extremely high chemical purity. Representative products AEROSIL® OX 50 and AEROSIL® TT 600 are widely used in ultra-thin outer layers of BOPET and BOPA films only a few microns thick, achieving antiblocking effects with almost no impact on film light transmittance, making them the preferred raw materials for optical films and high-end electronic packaging films.
For PET polycondensation addition processes and coating-type antiblocking demands, Evonik also launches the AERODISP® series of silica dispersions (such as AERODISP® G 1220 and VP Disp. G 6020 X), which pre-disperse fumed silica in ethylene glycol carrier. Customers can directly add them to the polymerization system or prepare coating solutions, avoiding the process difficulty of powder dispersion and ensuring ultimate dispersion uniformity.
4. Formulation Synergy and Processing Dispersion: Key Factors Unlocking Optimal Opening Agent Performance
The practical application effect of opening agent silica dioxide depends not only on the product’s own physical parameters, but also on formulation synergy logic and processing dispersion technology — which is also the core reason for substandard performance in many film enterprises.
4.1 Synergistic Combination with Other Film Additives
In practical film formulations, opening agents are usually used in combination with slip agents, processing stabilizers, UV absorbers and other additives. Among them, amide slip agents need to migrate to the film surface to function. If the opening agent has too high specific surface area and oil absorption value, it will adsorb a large amount of slip agent, leading to reduced slip effect and increased formulation cost.
Evonik's SPHERILEX® series and SIPERNAT® 44 MS adopt a structural design with low specific surface area and low oil absorption, with extremely low adsorption on slip agents. They can achieve synergistic "antiblocking + slip" efficiency, deliver lower friction coefficient at the same slip agent dosage, and avoid printing and heat sealing problems caused by excessive slip agent precipitation.
4.2 Core Technical Points of Processing Dispersion
The dispersion uniformity of silica particles is the core factor determining final film quality: insufficient dispersion can lead to film defects such as specks and fish eyes, and can also clog production filters, increasing equipment maintenance costs and scrap rates.
Evonik’s technical guide clearly states that opening agent silica dioxide requires uniform dispersion through high-shear processing equipment, and twin-screw extruders, Banbury kneaders and other high-shear mixing systems are recommended. Meanwhile, the product’s own physical properties also directly affect dispersion effect: particles with low or moderate specific surface area and oil absorption are more easily wetted by polymer melt, with lower dispersion difficulty; products with high bulk density are more suitable for high-concentration masterbatch production, improving production efficiency and reducing dust pollution.
Designed based on the above logic, the SPHERILEX® series and SIPERNAT® 44 MS feature excellent dispersion performance and high masterbatch loading capacity, helping customers simplify production processes and reduce comprehensive costs.
5. Full Coverage of Global Compliance Systems, Adapting to Multi-Regional Market Access Requirements
Food contact safety is the core access threshold for packaging films, and also one of the core competitiveness of opening agent silica dioxide products. All Evonik silica antiblocking products have passed food contact material certifications in major global markets, meeting customers’ global layout needs:
- Europe, Middle East & Africa
- Americas
- Asia-Pacific
In addition, the full product range is equipped with complete Product Safety Information (PSI) documents, which can provide customers with full compliance supporting documents and help customers quickly complete market access reviews.
Conclusion
With the continuous upgrading of global food packaging, pharmaceutical packaging, optical electronic films and other sectors, market performance requirements for opening agent silica dioxide are constantly evolving toward high clarity, high purity, high efficiency and low loss. With decades of technical accumulation and full-spectrum product layout, Evonik not only provides mature and reliable standardized products for the industry, but also provides customized formulation and process solutions for customers relying on its global application technical team.
The release of the TI 1206 technical guide further improves the technical theoretical system and application selection standards for silica opening agents, and will promote the standardized upgrading of antiblocking technology in the global film industry. Looking ahead, with the development of emerging tracks such as biodegradable films and functional films, Evonik will continue to iterate opening agent silica dioxide technology to provide more efficient, safer and more sustainable material solutions for the global plastics processing industry.
The news and information released by Zhonglian Chemical is provided solely for informational purposes and is intended only for reference and communication among industry professionals. It does not guarantee the accuracy and completeness of such information. You should not use this information to replace your own independent judgment; therefore, you shall bear the risks arising from any use of the information, and Zhonglian Chemical shall not be held liable. In case of any infringement, please contact us for removal.
Contact
Leave your information and we will contact you.
Phone
WeChat
WhatsApp