DE2636951A1 - Degrading starch or starch derivs. in paper prodn. - by treating with amylase to reduce viscosity and simplify coating process - Google Patents

Abstract

Amylases are used to degrade starch (derivs.) used in paper prodn. By partial degradation, the viscosity can be controlled to a desired value and the coating process simplified. For example, an aq. 7.5% soln. of a starch ether (e.g. 'Solvitose H') has a viscosity of 35 cP and pH 6.5. By adding 0.05% of an alpha-amylase (e.g. 'Biolase PC 90') the viscosity is reduced, the process being stopped by adjusting the pH to 3.5. This can be carried out, e.g. by adding acetic acid. The viscosity can be adjusted to any value between 35 and 2 cP, by varying temp., enzyme concn. and time.

Description

Starch degradation in the sizing of papers by means of amylases

The invention is based on the known fact that strength and Starch derivatives such as B. starch ethers and starch esters in aqueous solutions certain enzymes, namely amylases, can be broken down. The invention also works assumes that paper of various types and for different purposes is starch ether and starch esters are prepared or surface-glued. Be for this purpose these papers are coated with solutions of starch and / or starch derivatives. on This should reduce the porosity of the paper and the so-called ink resistance be improved. In addition, subsequent paper coatings are intended in this way aqueous and / or solvent-based are prevented from getting into the paper to penetrate.

The manner in which such lines of glue are applied or applied is known and can be done in a number of ways. But it will be a special one dense preparation of the base paper requires, then the solutions used must of starch and / or starch derivatives should be as highly concentrated as possible, because only those Solutions with a high solids content produce sufficient solutions with low application weights Tightness of the application and high effectiveness of the glue.

Unfortunately, such highly concentrated starch solutions are at room temperature difficult to process due to its high viscosity. They also wet the base paper insufficient and thus the glue is not sufficiently tight.

The invention intervenes here and shows how by enzymatic degradation (Partial degradation) of the starch or starch derivatives, the viscosity to a desired level can be lowered and thus the processing conditions for this spread facilitated and the effect of the sizing is improved.

One uses for the enzymatic degradation of starch and its derivatives Enzymes of the o (-amylase type. The starch breakdown itself is determined by measuring the Viscosity controlled and can be controlled by changing the pH.

An aqueous solution of 7.5 7o of a starch ether z. B.

Solvitose H (W. A. Scholten 's Chemische Fabrieken B.V.

Foxhol (GR) Nederland), has a viscosity of 35 cP and a pH value of about 6, 5. By adding an s -amylase z. B. Biolase PC 90 from Hoechst AG of 0.05%, the viscosity can be lowered. The breakdown of starch ether is interrupted by adjusting the pH to pH 3.5. This happens e.g. B. by adding acetic acid.

In this way, the viscosity of the starch solution can optionally be between 35 cP and 2 cP can be set. The degree of degradation or the final viscosity is high depending on the temperature, the concentration of the enzyme and the exposure time. Practically any desired viscosity can be set using these parameters. Often only a relatively minor reduction is sought, which is an adjustment of the Preparation to the conditions of the application unit allowed in an optimal form. This makes it easier to process.

Claims (1)

Claim Use of enzymes from the group of amylases as a means of breaking down starch and starch derivatives in papermaking.