Why does calcium carbonate need surface modification?

Unmodified calcium carbonate is the raw material, while modified calcium carbonate is the product. Many people wonder: Calcium carbonate itself is a high-quality and inexpensive inorganic filler widely used in plastics, rubber, coatings, building materials, papermaking and other fields. Why do we need an additional surface modification process to increase production costs? In fact, regular calcium carbonate and modified calcium carbonate have never been products of the same level. Untreated native calcium carbonate has many shortcomings, such as severe agglomeration, poor compatibility, easy product defects, and limited addition, which cannot meet the needs of mid to high end industrial production.

一、 The underlying principle of calcium carbonate modification

Calcium carbonate is a typical inorganic polar powder, with a large number of hydrophilic groups on the surface of the primary particles, and its core characteristic is hydrophilic and oleophobic. The vast majority of industrial substrates such as plastics, rubber, resins, and coating adhesives are made of organic oil-based materials. Surface modification of calcium carbonate involves the use of specialized modifiers such as stearic acid, titanate, and silane coupling agents to form an organic active thin film on the surface of calcium carbonate particles through coating, chemical bonding, physical adsorption, and other methods.

二、 What are the shortcomings of calcium carbonate without surface modification?

Many low-end products are produced using ordinary calcium carbonate, often resulting in problems such as cracking, powder loss, poor glossiness, bubble delamination, and low production capacity, which are essentially caused by defects in unmodified powder.

1. Extremely prone to agglomeration, low powder utilization rate. The higher the fineness and whiteness of calcium carbonate, the higher the surface energy, and the stronger the van der Waals force between particles. Unmodified ultrafine calcium powder will spontaneously agglomerate and cannot be uniformly dispersed. In production, it appears that high-quality fine powder has been invested, but in reality, it aggregates into large particles that not only fail to fill, toughen, and brighten, but also become impurities in the product, directly affecting its flatness and fineness.

2. Oil and water are incompatible, completely detached from the substrate. Native calcium carbonate is hydrophilic but not oleophilic, and when mixed into plastic, resin, and coating systems, it cannot tightly bond with organic substrates, resulting in a state of two-phase separation. The powder is simply mixed into the substrate without forming a stable interfacial bonding force, just like sand and glue forcibly mixed, with extremely poor viscosity and stability.

3. High oil absorption value increases production costs. The surface of unmodified calcium carbonate particles is rough, with many voids and loose stacking, resulting in generally high oil absorption values. In the production of coatings and plastics, high oil absorption values will consume a large amount of resin, additives, and oils, indirectly increasing raw material costs, while reducing system fluidity and affecting processing efficiency.

4. Poor acid resistance and short service life of the product. Native calcium carbonate has strong chemical activity and is prone to react with weak acids. In humid and acidic environments, it is prone to powdering, peeling, and aging, greatly reducing the weather resistance and service life of plastic products and coating materials.

三、 Surface modification! The core value of improving the quality and efficiency of calcium carbonate

Seemingly an additional process, it actually reduces costs, improves quality, increases production capacity, and expands the market. This is also the core reason why all high-end powder enterprises come standard with modified processes.

1. Eliminate agglomeration and significantly improve the dispersibility of modified calcium carbonate powder. The surface energy of particles is greatly reduced, and electrostatic repulsion is formed between particles, completely solving the problem of secondary agglomeration. Powder can be uniformly and finely dispersed in organic systems, fully utilizing the filling advantages of ultrafine powder to make the texture of the product finer and smoother.

2. Break down the compatibility barrier and achieve a deep fusion of powder and substrate with the organic coating layer of the modifier. One end is firmly bound to the inorganic particles of calcium carbonate, and the other end can be perfectly bonded to organic matrices such as resin, rubber, and plastic. The two originally incompatible materials form a stable interface structure, greatly improving the tensile strength, toughness, wear resistance, and impact resistance of composite materials, completely solving the problems of product cracking, powder loss, delamination, and delamination.

3. Reduce oil absorption value and effectively save raw material costs. Surface modification can fill the surface voids of calcium carbonate particles, optimize the powder packing density, reduce inter particle friction, and significantly reduce the powder's oil and resin absorption capabilities. Under the same filling amount, the usage of resin, additives, and solvents can be reduced, thereby lowering the overall production cost; Simultaneously enhancing the fluidity of the slurry, making production and processing smoother, and increasing equipment capacity.

4. Improve weather and acid resistance, extend product life. The modified calcium carbonate particles are completely encapsulated by an organic layer, isolating external water vapor, weak acids, and oxidizing media, greatly improving the chemical stability of the powder. Applied in outdoor building materials, anti-corrosion coatings, plastic pipes and other products, the anti-aging, anti pulverization, corrosion resistance performance is significantly enhanced, greatly improving the quality and service life of terminal products.

5. Increase the filling amount to achieve ultimate cost reduction. Unmodified calcium carbonate has poor compatibility, and excessive addition can directly lead to the collapse of product performance, severely limiting the filling ratio. Modified activated activated activated calcium carbonate has strong adaptability and can significantly increase the filling ratio without reducing product quality, replacing more expensive resin raw materials. It is the core filler for cost reduction and efficiency improvement in the plastic and coating industries.

四、 Industry wide applicability: Core application scenarios of modified calcium carbonate

Surface modification is not a high-end technological gimmick, but a must-have for the entire industry, covering almost all mainstream downstream of calcium carbonate:

1. Plastic industry: PE, PVC pipes, profiles, films, plastic accessories, improve toughness and glossiness, reduce the probability of shrinkage and cracking;

2. Rubber industry: tires, sealing strips, rubber products, enhance the reinforcement effect, improve the wear resistance and anti-aging performance;

3. Coatings and inks: interior and exterior wall coatings, industrial paints, inks, reduce oil absorption value, improve film fineness, covering power, and weather resistance;

4. Building materials industry: resin tiles, plastic steel materials, artificial stone, to improve the compactness and stability of products;

5. Paper industry: Improve the smoothness and whiteness of paper, reduce dust shedding, and improve paper toughness.