How to Select the Right Press Felt for Specialty Paper Production

Compared with conventional paper grades such as cultural paper and tissue paper, specialty papers require higher standards for surface quality, thickness uniformity, texture, and functional performance. Selecting the right press felt is essential for achieving consistent dewatering, sheet formation, and final paper quality. Different types of press felt are designed to meet the unique production requirements of specialty papers, including decorative paper, filter paper, security paper, and insulating paper. Choosing the appropriate paper machine press felt helps optimize production efficiency, improve paper quality, and ensure stable machine performance.

Specialty Papers Place Higher Demands on Press Felts

Different types of specialty paper use distinct raw materials and have specific requirements for manufacturing processes and physical properties. For example, some varieties focus on excellent surface smoothness, others require unique textures, and still others emphasize filtration performance, heat resistance, or electrical insulation properties.

This places higher and more exacting demands on the press felts used in the production of specialty paper.

For the past 30 years, Sun Hong has dedicated ourselves to the research and development of papermaking press felts. We have successively launched several major product series, including non-marking, anti-shedding, textured (needle-punched) blankets, as well as base-web composite and antistatic paper making felts, to meet the specific needs of specialty paper manufacturing.

Consequently, we have extensive experience producing press felts for specialty paper.

 

Key Properties of Press Felt for Specialty Paper Production

Different types of specialty papers vary in their properties and applications, necessitating specific performance requirements for the corresponding papermaking press felt.

Here, Sun Hong has conducted in-depth research into the characteristics and production requirements of various specialty papers and has summarized the following key considerations for selecting press felts.

Excellent Fiber Shedding Resistance

For certain specialty papers that require printing, such as wood-grain base paper and cork base paper, the requirements for fiber shedding from the press felt are extremely strict. If fibers shed from the press felt adhere to the paper surface, they can easily cause defects such as printing skips or clogging of the printing plate during subsequent processing.

Furthermore, if fibers continue to shed from the press felt and accumulate in the surface sizing solution, they not only tend to adhere to the paper surface but may also become trapped between the coating blade and the paper, resulting in linear coating scratches.

Therefore, for these types of paper, it is generally necessary to select press felts with high fiber-bonding strength and superior fiber shedding resistance.

No Felt Marks

Most specialty papers are required to be free of paper marks, especially some paper used for bills containing anti-counterfeiting watermarks, where paper uniformity and appearance quality are of paramount importance.

If the surface structure design of the press felt is poor, or if localized wear occurs after prolonged operation, felt marks may be left on the paper surface. This performance not only affects the clarity of the paper but also seriously compromises its aesthetic quality.

Therefore, if you need to produce this type of paper, it is generally necessary to use press felts with a finer surface texture, superior nip uniformity, and to leave no felt marks.

Features Distinctive Surface Texture

Not all specialty papers strive for a completely smooth surface. Some specialty papers, such as sketching paper and craft packaging paper, actually require clear, natural, and aesthetically pleasing striped marks on the paper surface.

Such textures are typically created using specially designed striped press felts, which impart a uniform and consistent surface pattern to the paper.

Therefore, when selecting the press felt, the decision should be made based on the appearance requirements of the final product, whether to reduce felt marks or to use the felts to create specific textures.

A Smooth & Fine-Textured Blanket Surface

This is a fundamental requirement for the production of press felts. If the felt surface is excessively rough, it will inevitably lead to an uneven paper surface, thereby compromising the quality of the finished paper.

Of course, for some types of paper, a rougher surface is actually required, in which case a press felt with a rougher surface must be selected for production.

Optimized Dewatering Performance 

Dewatering performance has always been one of the most critical characteristics of the press felt. In practical production, the dewatering requirements vary depending on the specific type of specialty paper being produced.

Different specialty paper grades call for different dewatering characteristics. 

For example, tracing paper is typically produced with highly refined pulp, resulting in slow drainage and difficult dewatering. In contrast, tea bag paper and filter paper are usually manufactured from less refined pulp with higher freeness, allowing water to drain more easily.

Therefore, it is crucial to select the correct press felt with appropriate water drainage, water retention, and re-wetting resistance properties based on the specialty paper you produce.

Acid Resistance Requirements

Some specialty papers are manufactured under acidic conditions, requiring the press felt to possess acid resistance. Therefore, felts produced from acid-resistant raw materials can be selected.

There is a wide variety of specialty papers, and the manufacturing processes and quality requirements vary significantly from one product to another. 

So, there is no single press felt that is suitable for all types of paper.