Synthetic Paper Varieties and Manufacturing Methods

Synthetic Paper Varieties and Manufacturing Methods

Resin-based synthetic papers are generally divided according to their manufacturing method into two broad categories: film synthetic paper and fiber synthetic paper. Currently, film synthetic paper is more commonly used. Several different methods have been devised to produce a paper that is similar in appearance to regular paper.

1. Film method synthetic paper

(1) Internal Paper-manufacturing Method

Filling material and additives are added to synthetic resin, and following fusion and kneading in an extruder, a film is formed by extruding the material through a die slit. With this method, the relatively thin fused resin pushed through the die slit can be treated in one of two ways. In the non-oriented film method, the output resin is simply hardened by cooling and prepared for commercialization. In the biaxial oriented film method, the fused resin is cooled temporarily, and then heat is added to re-soften it. It is then stretched in the longitudinal and cross directions, forming a film. As part of the biaxial orienting film method process, during stretching, tiny holes (micro-voids) may or may not be encouraged to form, producing two different kinds of products.

Our YUPO CORPORATION'S YUPO is a leading example of synthetic paper with micro-voids produced by the biaxial stretching film method.

(2) Surface Coating Method
Just as with ordinary coated paper, by adding a layer of pigment coating to a plastic film (including synthetic paper produced by the internal paper-manufacturing method above), this method can add properties such as whiteness, opacity, and suitability for writing and printing to the product.
(3) Surface Treatment Method
By chemically or physically treating the synthetic resin film surface, qualities such as suitability for writing and printing or opacity can be added with this method.

2. Fiber Synthetic Paper

(1) Synthetic Pulp Paper
Replacing pulp with resin fibers made primarily from synthetic resin, this is a synthetic paper made with an ordinary paper machine with binder added.
(2) Spun-bond Paper

In this method, synthetic resin is dissolved and injected through a nozzle, randomly lining up endless fibers formed as like synthetic fabrics. The fibers are then fused thermally in some areas, creating inter-fiber bonding. The whiteness and opacity of paper is achieved through the light-scattering properties of the fibers themselves and the irregular reflection caused by gaps that form between the fibers during production This kind of paper is characterized by its superior strength, but it is not as smooth and is of somewhat lower suitability for writing and printing.

This kind of paper is generally placed in the category of “unwoven fabrics,” but depending on the product it can be accepted as a synthetic paper in the market.

3. Film-Laminate Synthetic Paper

By laminating film on the surface of conventional paper, this method adds mechanical strength and water-resistance to the paper. By including tiny holes (micro-voids) in the film, the paper can be made to be nearly as fit for printing as conventional paper. Since the inner layer is paper, its water-resistance and strength is inferior to that of film synthetic paper.