Industrial Mineral Fillers and Custom Formulations for Composites
Mineral fillers are solid mineral particles—used individually or combined in various particle sizes—added to resins or gelcoats to manufacture polymer matrix composites. Choosing the right filler and fine-tuning its ratio with the resin directly conditions both the properties of the final product and the entire production process. At AITANACHEM, we formulate and blend mineral fillers for polyester, epoxy, and vinyl ester composites, and we develop custom mineral blends for specific projects, backed by full technical support from our laboratory.
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What are mineral fillers?
A mineral filler is a set of solid mineral particles incorporated into a composite formulation. They can consist of a single mineral or a combination of several, with single or multiple particle sizes depending on the target characteristics and required properties of the final product. Fillers are an essential component of any polymer matrix composite: they directly influence mixture viscosity, gel time, curing time, and, above all, the mechanical properties and final product cost.
What are mineral fillers used for in composites?
Adding mineral fillers to a resin serves several purposes. The proper combination of minerals allows manufacturers to:
- provide the physical and mechanical properties required by the final product: hardness, abrasion resistance, flexural strength, etc.;
- lighten or increase the weight of the composite as needed;
- enhance fire resistance through flame-retardant fillers;
- improve conductive or antistatic properties;
- lower total mixture cost, as mineral fillers are usually the most cost-effective component of the formulation.
The mineral composition and its ratio relative to the resin also dictate the manufacturing process: affecting viscosity, catalysis, shrinkage during curing and even the final color and surface finish. Therefore, selecting the right mineral fillers for composites is one of the most critical decisions in formulation design.
Mineral Filler Solutions for the Composites Industry
At AITANA CHEMICALS we work with a wide range of mineral fillers for composites. As the core hub of our offer, we group our solutions into four major technologies developed to meet the highest demands of the international B2B market:
Micronized Dolomite Fillers
Dolomite is one of the most widely used mineral fillers in in polyester composite manufacturing due to its excellent balance between performance and cost. It is commonly used as a bulk filler in gelcoated-coated parts, providing body to the mix and reducing production costs. Our high-purity, grain-size balanced dolomites are the most efficient choice to increase density and lower manufacturing costs. Thanks to their tailored particle size distribution, they offer exceptional wetting and fluidity during resin injection into the mold. Discover our dolomite fillers for composites.
Light weight mineral fillers (LWF)
Our low weight fillers (Light Weight Filler) are engineered formulations based on selected minerals and particle sizes that reduce composite weight by up to 40% without compromising the physical and mechanical properties of the finished product. This technology lowers transport costs, improves handling, and boosts plant productivity. It is widely applied in shower trays, bathtubs, polymer concrete, and other composite sanitaryware. Explore our light weight filler technology.
Reinforced fillers for polyester and fiberglass
Specifically formulated to be incorporated into resins used in hand lay-up or spray-up laminating processes alongside glass fiber reinforcement. They provide a significant increase in the mechanical properties of the laminated part, improve the thixotropic index to prevent sagging, and reduce overall resin consumption—lowering final production costs. We have extensive technical experience glass fiber reinforced gelcoat applications such as bathtubs, shower trays, spas, automotive parts, storage tanks, and glass recycling containers, among others.
Aluminium trihydrate (ATH)
Aluminium trihydrate (ATH) is the benchmark mineral filler when seeking enhanced fire resistance, acting as an effective flame retardant and smoke suppressor. It is widely used in rubbers, polyurethanes, polyesters, and cable manufacturing. Furthermore, ATH is the primary mineral filler in high-end solid surface manufacturing due to its high translucency, scratch resistance, and stain resistance. ATH is a core element of our raw material range for solid surface production, and we detail its properties on its dedicated page: all the information about aluminium trihydrate (ATH).
Technical Advantages in Industrial Production Processes
Using poorly balanced mineral blends or untreated fillers leads to thermal gradient warping, delamination, or gelcoat chipping. AITANA CHEMICALS mineral formulations are designed to solve these challenges in composite production:
- Silanized surface treatment: Ensures optimal chemical bonding between the polymer matrix and the filler, enhancing thixotropy and preventing phase separation during cure.
- Exothermic peak and HDT control: Balanced formulations that avoid internal stresses in the part, reducing the scrap/repair rate to below 2% and ensuring compliance with demanding thermal shock testing (CE marking).
- Machinery compatibility: Formulated for seamless operation in continuous screw mixing systems, flexible batch mixing systems, and piston casting machinery.
AITANACHEM: Custom mineral filler development and technical assistance
At AITANACHEM, we do not merely supply raw materials; we engineer advanced technical solutions tailored to each customer’s specific manufacturing process. In the thermoset resin industry (polyester, vinyl ester, epoxy, and acrylic), selecting the right mineral filler is decisive in achieving the perfect balance of cost, processability, and end-product performance.
Our specialist team provides personalized technical support and custom formulation development. We analyse the key parameters of your production line—temperature, viscosity, gel time, exotherm, and casting or injection machinery—to design mineral blends that ensure homogeneous dispersion, eliminate blistering or osmosis issues, and optimize business profitability. If you need to enhance product performance or develop a new composite material, get in touch with us.
Frequently asked questions about industrial mineral fillers (FAQ)
Why is controlling thixotropy and viscosity critical when adding mineral fillers?
Adding mineral fillers to thermoset resins increases mixture viscosity. A thixotropic index adjusted via additives or silanization allows the fluid mass to flow easily under vibration or pouring, while preventing denser mineral particles from settling to the bottom during gel time.
How do mineral fillers affect thermal shock resistance in sanitary ware?
A poorly balanced mineral fillers or low-HDT resins lead to high thermal expansion in demolded parts. When exposed to hot and cold water cycles, microcracks, cracks, or permanent warping occur. Our mineral fillers, developed specifically for composite sanitaryware, ensure long-term dimensional stability after thermal cycling.
Which mineral fillers are used in polyester composites?
It depends on the goal. Dolomite is the most common cost-reducing bulk filler; Aluminum Trihydrate (ATH) provides fire retardancy and is used in solid surface; reinforcing fillers improve mechanical strength in glass fiber laminates; and light weight fillers (LWF) reduce overall part density.
Can composite weight be reduced using mineral fillers?
Yes. Our Light Weight Fillers (LWF) reduce composite weight by up to 40% without losing structural performance, significantly lowering freight costs and easing manual handling.
Which mineral filler improves fire resistance?
Aluminium trihydrate (ATH) is the most widely used flame retardant: it releases water vapour in an endothermic reaction that cools the surface and suppresses smoke generation. That is why it is also used in the cable manufacturing.
What are the benefits of mineral filler silanization?
Treating fillers with silane coupling agents enhances translucency, thermal shock resistance, and mechanical and chemical durability, while reducing viscosity and shortening gel and cure times.
Do you develop custom mineral filler blends?
Yes. Our technical team analyzes client requirements and formulates bespoke mineral blends tailored to each project, adjusting density and performance parameters accordingly.
Looking to Optimize Your Formulations or Develop a New Product?
Our technical department is at your disposal to analyse your current manufacturing process, send test samples and formulate the exact mineral filler your project demands. Contact us today.
Expand your knowledge on our technical blog
We invite you to explore our specialized technical articles on improving composite properties through next-generation mineral fillers:
- Read our article on polymer concrete weight reduction
- Discover how to improve scratch resistance on solid surface parts
- Access all articles on Mineral Fillers on our blog