Advantages and Disadvantages of Transparent Filler Masterbatch and Production Process Experience

Gemme

02-18-2020 16:35:12

Transparent filler masterbatch refers to the process in plastic molding where various required additives and fillers are pre-mixed and compounded with a small amount of carrier resin for ease of operation. The resulting powder or granulate is called a masterbatch.

Overview of Transparent Filler Masterbatch:

Transparent filler masterbatch refers to the process in plastic molding where various required additives and fillers are pre-mixed and compounded with a small amount of carrier resin for ease of operation. The resulting powder or granulate is called a masterbatch. The main component of transparent filler masterbatch is nano-scale filler material with a refractive index similar to that of resin. It is mainly used in the processing and molding of polyolefins (polyethylene and polypropylene) and is also known as polyolefin transparent filler masterbatch.

Advantages of Transparent Filler Masterbatch:

Excellent Transparency:

Gemme Micron is an innovative functional filler material specially designed for blow-molded plastic products. Its near-nano-scale particle size and precise narrow particle size distribution curve create the optimal half-wavelength ratio, providing excellent penetration of visible light waves (390~780nm). Additionally, Gemme Micron has a unique refractive index of approximately 1.6, which perfectly combines with the particle size and shape, similar to the refractive indices of PE materials (1.51~1.54) or most other synthetic resins. The refractive index changes the direction of light due to the speed change when light enters another medium, hence Gemme Micron has been successfully applied in high-transparency blown films or cast polyolefin films, offering superior optical performance and opening properties. In agricultural insulation films and horticultural or aquaculture films, Gemme Micron helps in light scattering, infrared absorption, insulation, and preventing fog droplets, effectively increasing crop and ornamental plant yields and aquaculture survival rates.

Strong Dispersion Performance:

Gemme Micron features a special organic coating layer that shows excellent high dispersion compatibility in polymer systems. It is typically added to polyolefin systems and processed into concentrated masterbatch products, allowing molecular chains to encapsulate Gemme Micron nanoparticles and form a honeycomb arrangement, creating a more extensive force-bearing network. This significantly enhances the buffering capacity and impact resistance of the products, thereby improving tensile, puncture resistance, and abrasion resistance while controlling the product shrinkage to a very low level, thus shortening molding time and increasing production efficiency.

Excellent Surface Gloss:

Gemme Micron's L brightness value of up to 99.0 is significantly higher than the surface gloss L value of 40~90 for plastics, ensuring ultra-high levels of final product brightness. The spherical crystal structure and optimal light scattering efficiency and high reflectivity make it an essential functional filler material for high-gloss plastic products. It is also applied in LLDPE, LDPE, HDPE, PP, biodegradable, and other polyolefin materials in blow molding, extrusion, injection molding, and casting processes.

Compliance with RoHS, PAHs, Halogen, and FDA Regulations:

All production processes of Gemme Corp. are green and harmless, fully complying with and passing SGS RoHS, PAHs, Halogen, and FDA certifications, making them safe and reliable for use in products that adhere to children's and food safety standards.

Gemme Corp. in completing the official REACH registration with the European Chemicals Agency (ECHA) in 2013. The implementation of the European GHS chemical classification control measures and label management norms ensures that all final products using Gemme materials can smoothly and legally enter the EU market.

Composition of Transparent Filler Masterbatch:

Polyolefin filler masterbatch is composed of carrier resin, filler materials, and various additives, with fillers making up the main component, generally accounting for 80~90%. Extensive application practices have shown that when the filler content of transparent filler masterbatch exceeds 80%, transparency, dispersion, and other properties decrease. However, to gain better cost competitiveness, most masterbatch manufacturers often exceed filler content to 83% or even 87%, which reduces product quality and brings various application issues for customers.

Filler Materials:

The fillers used in polyolefin filler masterbatch mainly include nano barium sulfate, heavy calcium carbonate, and talc. It is well known that calcium carbonate and talc are mostly ground by mechanical milling, where finer particle sizes result in higher mechanical wear. Almost all mechanical wear components are mixed into the powder products. The production limit particle size D50 of mechanical milling processes like impact milling, air-swept milling, vertical milling, roller milling, and jet milling is 2 microns, which cannot meet the increasing application requirements. Nano barium sulfate, synthesized using BaCO3 + H2SO4, can achieve controllable particle sizes in the range of 50~300 nanometers, providing reliable assurance for various applications. Particle size and distribution curve span are important technical indicators for any inorganic filler. Generally, finer particle sizes and narrower distribution curves result in better filling effects. Additionally, good filling effects are related to dispersion. According to powder engineering theory, smaller particle sizes lead to higher surface energy, causing mutual adsorption between particles, making dispersion more difficult. To solve these issues, powder production companies usually add a liquid surface coating treatment after controlling the particle size during synthesis to maximize particle surface shielding and embedding, controlling oil absorption to very low levels. This increases the pigment base ratio and critical concentration, achieving better initial single-particle dispersion in polyolefin materials during application, thereby enhancing optical transparency and reinforcing tensile and fracture effects.

Carrier Resin:

The performance and cost of polyolefin filler masterbatch mainly depend on the carrier resin. Typically, the carrier resin content ranges from 10% to 20%, depending on the use of the masterbatch. The carrier resin used in polyolefin filler masterbatch should be highly compatible with the filled plastic matrix resin. Therefore, it is generally best to select the matrix resin as the carrier resin. Additionally, when choosing a carrier resin, its melting point and melt flow rate must be considered, ensuring the carrier resin's melting point is not higher than the matrix resin. Currently, linear low-density polyethylene (LLDPE) or polypropylene (PP) with similar melt indexes is commonly used.

Additives:

The additives used in polyolefin filler masterbatch mainly include dispersants or lubricants. The role of dispersants is to improve the flowability of the masterbatch during processing, facilitating more uniform dispersion within the matrix resin. Common dispersants include white oil, paraffin, polyethylene wax, coupling agents, and stearic acid.

Filler Masterbatch Processing Technology:

The processing technology and related equipment for polyolefin filler masterbatch change with the continuous improvement of carrier resins.

The first-generation polyolefin filler masterbatch (APP masterbatch) used domestic random polypropylene as the carrier resin, with the processing technology being mixing, open milling, water cooling, and pelletizing, involving batch production using mixers, open mills, and flat pelletizers.

The second-generation polyolefin filler masterbatch used LDPE (1F7B) as the carrier resin, producing PEP masterbatch. This process required specially designed single-screw extruders with large length-to-diameter ratios and high mixing performance for better results.

Polypropylene powder as the carrier filler masterbatch, known as PPM masterbatch, is considered the third generation of filler masterbatch in China. It generally uses a blend of polypropylene and polyethylene as the carrier resin, achieving excellent results. This product retains the characteristics and application range of PPM masterbatch while employing a hot-cut and air-cooling process, improving production efficiency and reducing raw material costs.

The best processing equipment for producing filler masterbatch is a co-rotating twin-screw extruder. This machine's advantages include continuous production, stable quality, high production efficiency, low energy consumption, low labor intensity, and a good operating environment.

Recommended Addition Ratios of Filler Masterbatch in Applications:

- Blow film PE (agricultural film, co-extruded film, civil film) -- 8%~12%
- Disposable tableware, milk and yogurt boxes, packing straps PP -- 40%~60%
- Cast coating, food packaging film, garbage bags, woven bags, shopping bags -- 20%~50%
- Extrusion molding, hollow molding LDPE -- 10%~40%
- Machine/hand straps, adhesive coating, paper coating, injection molding LDPE -- 10%~40%
- Foam sheets, foam products PP -- 20%~30%, PE -- 15%~30%
- Hollow blow-molded products, oil drums, plastic buckets, plastic bottles HDPE -- 10%~40%, PP -- 20%~40%
- Plastic trays, plastic basins, switch boxes, plastic toys, cosmetic boxes HDPE -- 10%~30%, PP -- 20%~30%
- Plastic curtains, plastic pipes, sheets, table mats PS -- 15%~30%, ABS -- 10%~25%

The above are reference addition ratios for conventional products. The specific amount should be determined based on product requirements and the quality of the filler masterbatch.