Organic compounds -- part of the class 532-570 series – Organic compounds – Carbohydrates or derivatives
Patent
1997-02-24
1999-11-30
Wilson, James O.
Organic compounds -- part of the class 532-570 series
Organic compounds
Carbohydrates or derivatives
536 45, 536 47, 536 553, 162158, 162175, 106210, 4351723, 4353201, A23G 300
Patent
active
059945320
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to the use of amylopectin-type starch or derivatives thereof as a finishing agent in papermaking.
More specifically, the present invention relates to the use of amylopectin-type starch obtained from potato that has been modified by genetical engineering, to suppress the formation of amylose-type starch.
BACKGROUND OF THE INVENTION
In the manufacture of paper and paperboard intended for some kind of printing the print-receiving surface is treated either by a pure starch solution or by a coating slip. When traditional starch of any known origin (potato, maize, wheat and tapioca) is used, more than one chemical modification step is required in many cases to obtain a product possessing sufficient stability. The various modification steps usually include a stabilising step, for instance an etherification reaction with propene dioxide or an esterification reaction with vinyl acetate or acetic anhydride, and a degradation step, such as oxidation, enzymatic degradation, acid hydrolysis or so-called thermo-chemical conversion. During the above steps substitution of the starch takes place, and the degree of substitution pertaining to the corresponding stabilising step usually amounts to 0.01-0.5 mole/mole glucose, preferably 0.05-0.20 mole/mole.
The necessity to carry out more than one modification step entails costs and has negative effects on the environment, and a reduction of the required number of chemical modification steps thus is desirable.
OBJECTS OF THE INVENTION
The object of the present invention is to reduce the number of chemical modification steps necessary to obtain a stable finishing agent for use on paper. This object is achieved by using amylopectin-type starch of the kind out-lined in the introduction, which starch additionally possesses the characteristics defined in the appended claims.
SUMMARY OF THE INVENTION
In accordance with the present invention amylopectin-type starch or derivatives thereof thus are used as a finishing agent in papermaking.
The expression "amylopectin-type starch" as used throughout in the present application text relates to starch obtained from potato that has been submitted to genetical engineering in order to suppress the formation of amylose-type of starch. The expression "derivatives thereof" relates to chemically, physically and/or enzymatically derivatised amylopectin-type starch. The amylopectin content of amylopectin-type starch is in excess of 95%, preferably in excess of 98%. The remaining ingredient in amylopectin-type starch is amylose.
A detailed description of the above amylopectin-type starch and derivatives thereof and the methods of their production is found in the Swedish Patent Specification 9004096-5 (Amylogene HB).
When practising the invention, amylopectin-type starch is added in amounts of 0.5-8% by weight, preferably 2-6% by weight, during the production process.
By means of the present invention it thus becomes possible to eliminate the above-mentioned stabilising step, since the amylopectin in the starch used in accordance with the invention, having strongly reduced amylose contents on account of its branched structure, possesses excellent stability. Thus, only one chemical reaction is required to produce the finishing agent, and consequently surface-sizing and coating products may be manufactured in a manner that is considerably less harmful to the environment than has hitherto been possible. The reason therefor is not only the elimination of the modification step but also that it has become possible to alter the degradation step. In consequence of this alteration the amount of oxidising agent required to degrade the amylopectin in the starch used in accordance with the invention is approximately 50% lower than the amount required to degrade traditional potato starch. In general, sodium hypochlorite, hydroperoxide or some type of persulphate compound, such as sodium persulphate, is used as the degradation chemical.
It is not previously known to use amylopectin-type starch as a finishing agent for use on p
REFERENCES:
patent: 5365016 (1994-11-01), Burrell et al.
Sveriges Starkelseproducenter Forening UPA
Wilson James O.
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