Commonly used auxiliary materials for coated abrasives

+ 查看更多

Coated abrasives play a vital role in various industries, providing efficient grinding and polishing solutions. Alongside the primary abrasive particles and bonding agents, the use of auxiliary materials enhances the performance and application of coated abrasives. This article explores the common auxiliary materials used in the coated abrasives industry and their functions.

1. Softeners:

Certain bonding agents can result in rough and brittle film formation after drying, making it susceptible to mechanical stress, cracking, and detachment. To address these issues, softeners are often incorporated during the slurry preparation process to increase the flexibility of the coating, preventing film fracture. Softeners work by loosening the molecular bonds of the bonding agent, thereby enhancing its plasticity. However, excessive use of softeners can negatively impact film strength, making their application a balancing act. Commonly used softeners include butter, coconut oil, cottonseed oil, lard, linseed oil, peanut oil, and rapeseed oil. These softeners should possess stable performance, uniformity, high and stable melting points, low moisture and ash content, a moderate acid value, a high saponification value, and a low iodine value.

2. Wetting Agents:

During the coating process, achieving uniform and rapid adsorption of the slurry onto the substrate can be challenging due to various factors. These include the short contact time between the fabric and slurry (less than a second), low fabric temperature resulting in increased viscosity, the high surface tension of the slurry, the presence of waxes, fats, pectin, and impurities on the fabric, and trapped air in the fiber gaps. To improve the wetting conditions, wetting agents, commonly surfactants, are added. These agents possess a linear molecular structure, with one part being hydrophilic and the other being hydrophobic. They help reduce surface tension and increase slurry diffusivity and flowability, facilitating the penetration of the slurry into the fabric. Popular wetting agents include Turkish red oil, dispersing agents, and leveling agents.

3. Fillers:

Fillers serve the purpose of partially replacing the bonding agent, reducing consumption, and achieving effects such as filling, reinforcement, abrasion reduction, and cost reduction. Fillers should have a fine and uniform particle size, excellent compatibility with the bonding agent and other components, and appropriate dosage to avoid negatively impacting film quality. Commonly used fillers are inorganic minerals such as clay, bentonite, and talcum powder.

4. Preservatives:

Natural bonding agents are prone to microbial degradation, leading to spoilage. Therefore, the addition of preservatives to the slurry is necessary. Chemical-based slurries generally require less or no preservatives. Commonly used preservatives include para chlorophenol, formaldehyde, and sodium carbonate.

5. Humectants:

To allow the coated film to absorb ambient moisture and maintain a certain level of humidity, humectants like glycerol can be added.

6. Defoamers:

During the slurry preparation or coating process, excessive foam generation can hinder the coating operation. To counter this issue, small amounts of defoamers are added. Common defoamers include turpentine, n-butanol, and certain oils.

7. Colorants:

Colorants are used primarily for enhancing the appearance of coated abrasives. Organic direct dyes are commonly employed as colorants.

8. Solvents:

Water is the most commonly used solvent, although some organic solvents are also used.

In addition to the mentioned auxiliary materials, there are other components such as dispersing agents, anti-static agents, and solubilizers that serve specific purposes within the coated abrasives industry.

Auxiliary materials play a crucial role in the development and enhancement of coated abrasives. The addition of softeners improves the flexibility of the bonding agent, preventing film fracture. Wetting agents facilitate the uniform and rapid adsorption of the slurry onto the substrate. Fillers reduce the consumption of bonding agents and provide additional benefits such as reinforcement and cost reduction. Preservatives help protect natural bonding agents from microbial degradation. Humectants maintain the desired moisture level in the coated film. Defoamers prevent excessive foam generation during the coating process. Colorants enhance the visual appeal of coated abrasives. Solvents are used as the primary medium for slurry preparation.

The proper selection and dosage of these auxiliary materials are essential to achieve optimal performance and quality of coated abrasives. Manufacturers must consider factors such as compatibility, stability, and the intended application of the final product.

As the coated abrasives industry continues to evolve, research and development efforts focus on improving the properties and functionality of auxiliary materials. Ongoing advancements in material science and technology contribute to the development of new and innovative auxiliary materials that further enhance the performance and versatility of coated abrasives.