How can the water and oil resistance of PE coated cup paper roll be adjusted by coating thickness and formulation?

The waterproof and oil-proof properties of PE-coated cup paper rolls mainly come from the polyethylene (PE) film coated on its surface. PE coating not only provides excellent waterproof performance, but also effectively prevents grease from penetrating. Therefore, the thickness of the coating, the formulation of the material, and the production process have an important impact on its final performance. Here are several ways to optimize the waterproof and oil-proof properties by adjusting the coating thickness and formulation:

The coating thickness is positively correlated with the waterproof performance. The thicker the PE coating, the stronger the waterproof performance, because the thicker coating can effectively prevent water from penetrating into the paper surface. However, too thick a coating may cause the paper surface to be not smooth or flexible enough, so a balance needs to be found to ensure that the coating thickness is sufficient to provide waterproof effect without affecting the overall performance of the cup.

Similar to waterproof performance, the thickness of the PE coating directly affects its oil-proof ability. Grease molecules can penetrate into the interior of the paper more easily than water molecules, so the requirements for oil-proof performance are usually higher than those for waterproof performance. When the coating thickness is moderate, the PE coating can effectively prevent grease from penetrating. But if the coating is too thin, grease can easily penetrate the coating and penetrate into the paper surface. Therefore, the appropriate coating thickness can ensure the oil-proof effect while avoiding excessive use of coatings, thereby optimizing costs.

The formulation of PE coatings (mainly the type of polyethylene, adhesives, fillers, etc.) also has an important impact on the waterproof and oil-proof performance. By adjusting the key ingredients in the formulation, the performance of the coating can be improved:

Different types of PE (such as low-density polyethylene LDPE, high-density polyethylene HDPE, linear low-density polyethylene LLDPE, etc.) have different molecular structures and physical properties, and these different types of PE have different waterproof and oil-proof properties. For example, low-density polyethylene (LDPE) has better flexibility and more uniform coating effects, which is suitable for applications that require higher waterproof and oil-proof properties; while high-density polyethylene (HDPE) is more rigid and is suitable for applications that withstand higher pressure or require enhanced anti-permeation properties.

Adding some additives (such as plasticizers, antioxidants, stabilizers, etc.) to PE coatings can further improve their performance. For example, plasticizers can increase the flexibility and ductility of the coating and prevent the coating from cracking or falling off; while antioxidants can improve the durability of PE coatings and extend the service life of the product. At the same time, the addition of surfactants helps to improve the adhesion of the coating and enhance the bonding between the coating and paper, thereby improving its waterproof and oil-proof properties.

Sometimes some inactive fillers (such as talcum powder, titanium dioxide, graphite powder, etc.) are added to the PE coating. These fillers can improve the physical properties of the coating, reduce the permeability of the coating, and improve the waterproof and oil-proof effects. Adding an appropriate amount of fillers can make the coating more uniform and improve its durability.

In addition to adjusting the coating thickness and formula, the coating application process (such as coating method, temperature, pressure, etc.) also has an important impact on its waterproof and oil-proof properties:

Common PE coating application methods include cast coating, blade coating, and spraying. Different coating methods affect the uniformity and thickness of the coating, thereby affecting the waterproof and oil-proof effects. Cast coating usually provides a more uniform coating thickness, so it helps to improve waterproof and oil-proof properties; while blade coating and spraying may be more suitable for some specific applications and need to be selected according to product requirements.

The curing process of the coating is crucial to its performance. After coating, the PE coating needs to be heated and cured so that it adheres to the surface of the paper and forms a strong film. By adjusting the curing temperature and time, the density and strength of the coating can be controlled, thereby improving its waterproof and oil-proof effects. At the same time, proper pressure control can ensure that the coating is smooth and uniform, reduce bubbles or uneven areas in the coating, and avoid affecting its protective properties.

Adjustment of coating thickness and formulation not only affects the waterproof and oil-proof properties, but also affects the mechanical strength and toughness of the paper itself. Although thicker coatings can improve waterproof and oil-proof properties, they may cause the paper to become harder, affecting the forming and pressure resistance of the cup. By optimizing the PE ratio in the formula and the use of additives, the flexibility and strength of the paper can be maintained while ensuring the waterproof and oil-proof effects.

PE coated paper rolls are widely used in hot drink cups, so its heat resistance is also an important factor. By adjusting the formulation and thickness of the coating, the thermal stability of the PE coating can be improved to prevent it from melting, deforming or failing under high temperature conditions.

In addition to the conventional waterproof and oil-proof functions, some applications may require the coating to have other special functions. For example, anti-ultraviolet (UV) coating can help prevent the effects of ultraviolet rays on paper and liquids; antibacterial coating can effectively reduce the growth of microorganisms and ensure the safety of food in the cup. To meet these special needs, the formulation and thickness of the coating can be customized according to specific functional requirements.

By adjusting the coating thickness and formulation of PE coated cup paper rolls, its waterproof and oil-proof properties can be precisely controlled. The thicker the coating thickness, the stronger the waterproof and oil-proof properties, but too thick a coating may affect other physical properties of the paper, such as flexibility and strength. By selecting the appropriate PE type, additives, fillers and coating process, other properties of the product can be optimized while ensuring the waterproof and oil-proof effects. In addition, the optimization of the coating process, such as reasonable control of temperature and pressure, can also help improve the uniformity and adhesion of the coating, thereby improving the overall quality of the product.