what you need to know about starch in papermaking.

by:ZHENHUA     2020-03-29
The application of starch in paper making dates back to the invention of the paper itself before 2000, when starch was applied to paper to obtain a stronger and smoother writing surface.
For mineral fillers containing paper, starch is the material with the largest volume after water, fibers and fillers.
Starch helps paper making by providing functional properties and as a process aid.
The paper mill uses starch from various sources such as common corn, glutinous rice, cassava, potatoes and wheat.
Usage depends on availability and economics for a given area.
According to market estimates, the global consumption of paper starch includes 67% corn, 15% potatoes, 8% cassava and 3% glutinous rice.
Starch manufacturers sell \"natural\" and several modified starch to the paper industry.
Factories usually buy starch in dry powder form and cook on site before applying.
In general, modified starch has better value than natural starch, combined with the application expertise of starch suppliers to provide more consistent starch quality.
The utilization of starch in paper-making depends on the type of paper, other raw materials used, paper-making technology, desired final performance and the demand for paper-making productivity.
For example, the tissue grade usually uses a small amount of starch or does not use starch, while the paper weight of fine printing and writing paper can use up to 10% of starch.
More starch is used in paper grades containing higher mineral fillers to maintain strength and print performance.
Starch has traditionally been used as a dry strength and surface improvement agent.
But in alkaline paper making, starch is wet-end sizing.
Starch is an integral part of the particle retention system.
Surface starch is also used as an adhesive, water retention agent and carrier for surface sizing chemicals and other functional additives.
The global paper industry uses about 5 million tons of starch per year.
This is equivalent to about 1.
In all grades of paper and cardboard, the starch content is 5% by weight.
In the United States, the use of modified starch is more common, and modified starch not only increases productivity, but also improves the quality of paper.
In 2004, for example, all of the corn
According to the Association of corn refiners, 76% of starch used in the US paper industry is modified. Corn-
In the US paper industry, starch accounts for more than 95% of all starch utilization.
During 2004, the consumption of modified corn starch increased by 14% compared with 2003, while the consumption of natural corn starch decreased by 10.
5% in the same period.
Including starch from other raw materials, the share of modified paper starch in the United States is even more than 76%.
Of all the modified corn starch transported by members of the Association of corn refineries, 66% is used for paper making.
In contrast, less than 60% of the starch used by the Asian paper industry is modified starch.
As environmental law enforcement in Asia is becoming more stringent and paper quality is improving, it will become a trend to use more modified starch to control waste emissions, improve paper quality and increase productivity.
As Asia\'s economy and living standards continue to grow, paper production is also expected to grow accordingly.
Transgender starch opportunities in Asia are expected to grow at a faster rate than paper production, as paper quality has improved and utilization of recycled fibers, agricultural fibers and mineral fillers is higher than usual.
As mentioned earlier, the contribution of starch to paper making, when the paper is mainly made of fibers, starch is traditionally used to give dry strength and enhance surface integrity.
Over time, with the use of non-traditional raw materials for paper making, including recycled fibers, agricultural fibers, mineral fillers, evolved into a complex process, the requirements have changed and countless chemicals designed to improve the paper making process and the performance of functional paper.
Today, starch is used in wet end applications with pulp to enhance dry strength, including thickness bonding and stiffness of paper, and to improve powder and chemical retention, drainage, internal sizing, formation and printing suitability.
It is also used to reduce the demand for refined energy, biochemical oxygen, and the total cost of paper manufacturing.
Surface starch improves the surface as well as the internal strength and printing suitability.
Figure 1 shows the contribution of starch to paper making.
For example, when used, modified wet-end starch allows more use of low-cost mineral fillers to replace expensive fibers and reduce refining energy requirements by providing additional paper strength.
The reduction in refining allows for additional drainage on the wires, thus saving energy in pressing and drying operations.
Wet-end starch is also a protective gel with the active size in alkaline paper making. Wet-
The final starch anchors and distributes the active size into the paper fiber, thereby increasing the cleanliness and productivity of the paper system.
There are many examples of productivity improvement.
In one case, a paper mill using extra wet-end starch eliminates wet press picking, enabling its paper machine to run for longer periods of time without breaking.
In another case, the use of modified wet-end starch instead of synthetic polymer as an emulsion of reactive alkaline size eliminates deposits on paper machine elements and increases productivity.
However, when using modified surface starch instead of natural starch converted on site, another paper mill was able to reduce the total amount of starch used and the stripes on the paper machine.
The use of modified starch in this factory not only reduces paper scraps, but also simplifies the starch preparation system. [
Figure 1 slightly]
The starch application method applies starch to several stages of the paper making process through different methods to achieve the desired results.
For example, it was found that the use of uncooked spray starch at the wet end between layers of multiple grades increases the layer bonding strength.
Mixed cooked, improved wet
End starch in pulp improves strength, sizing, retention, drainage, formation, quality of wastewater and productivity.
The correct selection and application of modified starch ensure the above benefits.
Starch addition rate, point of addition and compatibility with other wet-end chemicals are also critical for the best performance of the selected wet-end chemicalsend starch.
The application of starch in various paper making steps is shown in figure 2.
Most of the starch is applied to the surface of the paper through a pond or metering Press.
The surface starch applied with the press machine increases the internal strength and improves the surface integrity, printing suitability and surface strength.
In some cardboard grades, surface starch is used in conjunction with the calender to reduce blur and increase the hardness, print suitability, surface strength and curl trend.
In order to reduce the cost of coating, some paper mills use starch solution as a pre-set on the calender and tablet press
Coating before applying expensive coating chemicals.
In the coating grade, starch acts as an adhesive and Rheo modifier in the water-based coating and reduces costs by replacing expensive synthetic chemicals.
Because starch is natural, renewable and biodegradable, it is friendly to the environment.
Compared with natural starch, the advantages of modified starch are various, including increasing productivity and improving quality.
As paper machines become faster and faster, the impact of downtime and downtime is also increasing
Grade paper becomes very expensive.
Therefore, the best value that modified starch provides than natural starch is to reduce downtime and improve paper quality.
Other benefits include.
* Improvement of wastewater discharge quality with live starch * elimination for on-
On-site conversion of natural starch * reduced labor costs due to the simplicity of cooking and using modified starch * Improved stability of cooked starch, thus reducing the rejection rate of starch * achieving a consistent process change * the whole operation has been strengthened due to the service of the supplier and the application of best practices. A paper mill has significantly improved the quality of white water and paper by replacing the natural starch at the wet end with cation starch.
In order to achieve a similar effect, the factory also reduced the amount of starch used by cation starch.
Another paper mill saw that when using modified surface starch instead of natural starch converted on site, the overall manufacturing cost was reduced, the paper properties were improved, and the starch preparation system was simplified. [
Figure 2:
According to the raw materials and modification methods, there are several types of starch.
Ten years ago, potato starch was the dominant modified wet-end starch in the United States;
However, due to the cost and availability, most of this starch is replaced by modified corn starch at the wet end.
In Europe, transgender corn starch also permeates the wet end due to cost problems, although the area is known for potato starch.
In Asia and Africa, cassava is being used in some paper mills
Wheat starch is used in Australiabased starches.
In most cases, the wet-end starch is cation or both sexes, while the surface starch is oxidized or contains oh.
Some relatively new wet-end starch including cross-starch
Liquid or intervention-
Gel and highly charged wet end starch.
Other modified starch used for surface applications include phenol-based, ethynated, acid-modified, phosphate and starch.
The changing demand for paper making provides the opportunity for starch manufacturers to develop an updated grade of starch to help improve paper quality and productivity.
Starch application experts help paper makers to select the right starch type for a given application for optimal productivity, quality and manufacturing costs.
For centuries, various types of starch have played a key role in improving paper quality, increasing productivity and reducing total costs.
Starch is a natural biodegradable product that is considered eco-friendly compared to synthetic chemicals.
Since starch is a rich renewable product, it provides paper mills with economic value unmatched by other chemicals.
It still offers the best value in terms of paper strength.
With the increasing use of alkaline paper making, starch has become an important part of the alkaline sizing plan, and starch used as a polymer has become an important part of the particle retention system.
Increasing the use of modified starch is not only to improve quality and productivity, but also to meet or exceed rising environmental standards.
Some paper mills use natural starch due to lower prices, but due to productivity losses and lower paper quality, the total cost of using natural starch may be higher than that of modified starch.
Paper mills must focus on the main objectives of producing paper and cardboard at the highest quality and minimum cost.
Since starch preparation systems in many paper mills are not considered to be highly preferred, natural starch transformed on site may in fact increase the total cost of manufacturing due: * waste of quality starch * use of labor, chemicals and energy, and * production of high grade paper.
Starch suppliers that provide appropriate selection and application of modified starch can help paper makers achieve or exceed their goals.
Author Ashok Kumar Mishra is a director of the Asia/Africa division of Corn Products International
Westchester, Illinois, United States of America
Comments, questions and other information can be sent to the Author by email at: ashok.
Mishra @ cornproducts. com.
He has more than 27 years of work experience in various abilities of the paper and starch industry.
He holds a graduate degree in thesis science and management and lives in Neville, Illinois. [
Slightly] Illustrations
ASHOKKUMAR Mishra, Corn Products International Trading Co. , Ltd.
What are you going to learn * how starch promotes the paper making process * global trends in starch use * starch application methods * benefits of using additional resources of modified starch * starch and starch products to paste and paper coating on the surface, h. W. Maurer, ed.
ISBN: 1930657560.
This monograph discusses the properties and uses of starch, in particular the application of starch and starch products in sizing and coating on the surface of paper and cardboard. 2001.
170 pages, soft cover.
This article is provided by TAPPI Press.
For more information, please visit www. tappi.
Organize and enter the following product code in the search field. 0101R297.
Or call 800 332-8686.
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