Acid-free kraft paper is kraft paper that does not contain active acids. It is solid, strong, close to neutral, with a PH value of 7.0 or above. Acid-free kraft paper is made from plant fiber wood pulp or bamboo pulp with special treatment (eliminating the organic acids present in it) and copied on a paper machine. Acid-free kraft cardboard can be stored longer and has a lifespan of more than 200 years.
Features: The main features are high tensile strength, good smoothness, high breaking strength, uniform paper; The surface is flat; the longitudinal and transverse tension is strong; the wood pulp and bamboo pulp fiber content is high, and the paper items packaged with acid-free kraft paper are not easy to fade and deteriorate and have the characteristics of insect resistance and mildew prevention.
The paper machine generally uses shorter, weaker fiber paper, but the fiber direction in the paper it produces is exactly the opposite of the handmade paper.
Uses: Mainly used to pack some items that need to be stored for a long time or used in the manufacture of certain equipment, protecting materials in contact with paper from acid erosion. Acid-free kraft paper can be used as an important data file box, document bag information bag, important literature book cover, etc., under normal use and preservation conditions, acid-free kraft paper service life of about two hundred years.
But with the emergence of various new inventions, the drawbacks of this papermaking method have gradually emerged. Paper machines generally use shorter, weaker fibers to make paper, but the fibers in the paper it produces are in the opposite direction to handmade paper. The advent of alum and rosin helped people solve this problem. Alum, also known as aluminum sulfate, has been used as a sizing agent in the mechanical papermaking process since the 19th century to the present. Acid-free kraft paper recommended,
The purpose of sizing is to enhance the affinity between the paper fibers and reduce the absorption of the ink by the paper. However, alum and rosin are also the main sources of harmful acids in paper.
Over time, acid is the main culprit in the destruction of books and literature. In fact, the pH of the paper proved to be the main cause of the loss of strength and fading of the paper. By using synthetic non-acidic sizing agents and adding calcium carbonate (a mild alkaline buffer) to the pulp, the first permanent paper was finally produced in a regular factory.
Since the 1880s, more paper mills have switched to alkaline paper (acid-free paper) production processes because of the low cost and long life cycle, and the production process of acid-free paper is less harmful to the environment.
