Publish Time: 2025-12-12 Origin: Site
In the paper industry, in addition to original starch, chemically modified starch such as oxidized starch, cationic starch, and esterified starch are also commonly used.
Oxidized starch, a common modified starch, has a white color, is easy to gelatinize, and the viscosity of the paste is stable, with good transparency and film-forming properties. This starch is treated with sodium hypochlorite oxidant to depolymerize and produce a low viscosity dispersion, which introduces carbonyl and carboxyl groups to improve its stability. Oxidized starch is commonly used for surface sizing.
Cationic starch is a product of reaction with cationic reagents, mainly occurring on the active hydroxyl groups at positions 2, 3, and 6 of the glucose unit. The degree of denaturation is measured by the degree of substitution (DS), with a theoretical maximum degree of substitution of 3. The commonly used cationic starch in the paper industry has a relatively low degree of substitution, usually between 0.03 and 0.04. Although there are high substitution cationic starch products on the market with higher prices, their applications are limited. The common cationic starch is quaternary ammonium cationic starch, commonly used for wet end (pulp) addition.
The molecular formula of quaternary ammonium cationic starch is C6H11N (CH3) 3, and its unique molecular structure endows it with excellent physical and chemical properties. In the paper industry, quaternary ammonium cationic starch is often used as a wet end additive, which can effectively improve the strength and fiber retention of paper, while also increasing vehicle speed and reducing the number of paper breaks, thereby improving production capacity. In addition, it can also synergistically interact with anionic derivatives such as starch phosphate monoesters to further optimize paper properties.
On the other hand, esterified starch used in the paper industry, especially phosphate starch, also plays an important role. Phosphoric acid can react with hydroxyl groups in starch molecules to form monoesters, diesters, and triesters of phosphoric acid, among which monoesters of phosphoric acid are the most widely used. This anionic derivative significantly improves the viscosity, transparency, and stability of the paste. In coating formulations, phosphate starch can replace higher cost adhesives such as styrene butadiene latex, achieving a dual improvement in economic benefits and environmental performance.
In summary, starch is widely used and indispensable in the paper industry. Its unique physical and chemical properties significantly improve paper performance, while also helping to improve production efficiency and reduce costs.
In the paper industry, adding starch to the wet end (pulp) is a key step. Generally, cationic starch is the preferred wet end starch, especially widely used in the production process of cultural paper and packaging paper. In some complex systems, amphoteric starch is sometimes also used.
However, the efficacy of wet end starch is not solely influenced by starch sources, modification techniques, and production batches. The effectiveness of this is closely related to multiple factors, such as the precise selection of wet end starch spot positions, interference from other substances in wet end chemistry, the quality and composition of the pulp, and the operating conditions of the pulping and paper machine systems. The combined effect of these factors will directly affect the performance of wet end starch in the papermaking process.
Inter layer spraying
In order to enhance the interlayer adhesion of multi-layer cardboard, many cardboard production companies choose to use original starch for interlayer spraying. This spraying operation is usually carried out at the following locations, and the specific usage amount is determined according to actual needs, usually around 1g/m2.
Surface Sizing Application
Surface sizing is the process of evenly applying a sizing agent onto the surface of paper to enhance the adhesion between fibers and the paper body, forming a continuous thin film. In the paper industry, the commonly used sizing agent is modified starch, which accounts for a large proportion of the total starch used in papermaking.
Method of Adding Surface Adhesive Starch
In the papermaking process, surface sizing can be achieved through various sizing and pressing methods, among which the most common are immersion sizing and metering rod sizing and pressing. These two methods each have their own characteristics and are suitable for different product performance requirements. Generally speaking, the amount of starch applied on the surface of cultural paper is controlled at around 1-2g/m2 to ensure the performance and quality of the paper.
Soaking Size Press Method
In the papermaking process, soaking size press is a common method of sizing. The principle is to pass the paper through a solution containing surface adhesive starch, so that the starch evenly covers the surface of the paper. By controlling the soaking time and starch concentration, precise control of the surface properties of paper can be achieved. This sizing application method is suitable for various types of paper and can meet different product performance requirements.
Measurement Rod Size Press Method
In the papermaking process, the size press of measuring rods is an important technical step. The core of it is to evenly apply a solution containing surface sizing starch onto the paper through precise measurement, thereby achieving precise control over the surface properties of the paper. This sizing application method is not only suitable for different types of paper, but also meets diverse product performance requirements.