Two corrugated board <br> <br> binding mechanisms make unitary structure formed of corrugated board, adhesive is essential. Adhesives (glues) not only affect the production efficiency of corrugated board, but also have a great influence on the quality of corrugated paper. It plays an important role. Therefore, here I would like to briefly review the history of the development of corrugated board adhesives.
(a) History of development of corrugated cardboard adhesives
The earliest corrugated cardboard adhesive was sodium silicate. Sodium silicate, also known as water glass, is a very viscous liquid. Its properties generally vary with the ratio of the total molecular weight of silica and sodium oxide. Usually, the ratio of 3:1 to 4:1 is more often used.
The use of sodium silicate-bonded corrugated board offers several advantages over starch-bonded corrugated board. For example, the carton has a high compressive strength, and the shoulder formed by the glue line has a high water resistance.
However, its fatal disadvantage is that it is easy to cause so-called "alkali stain" on the surface of corrugated paper, causing the printing surface to be contaminated, thereby significantly reducing the commercial value of corrugated boxes. The cause of alkali stains is due to the fact that sodium silicate is decomposed by water after absorption of moisture, and the separation of alkali causes deterioration of paper and ink. This change is exacerbated in particular in high-humidity climates. Due to this fatal flaw of sodium silicate, people started to improve on the one hand, and on the other hand, devoted themselves to the development of new adhesives. Of course, the development of new adhesives is also aimed at improving the production efficiency of corrugated board.
The development of semi-chemical pulp and the appearance of kraft face paper have announced that the era of yellow core paper made from wheat straw as the main raw material has come to an end. This new type of noodle paper makes corrugated cardboard move toward high speed and wide width.
In 1956, starch was first introduced into Japan as a binder for corrugated paper, which laid the foundation for the development of modern corrugated paper industry. In this process of transformation, the machinery for producing starch pastes with good performance in agitation has provided a great impetus for the development of the corrugated paper industry in the world.
(b) Starch
Starch is a high-molecular substance that is produced in plants by the combination of carbon dioxide and water and light energy. Usually we call this reaction "photosynthesis."
The plant itself also consumes part of the starch, but it is mainly stored as a chlorophyll and a nutrient source for photosynthesis that are needed to form the next-generation plant. Although starch is found everywhere in plants, most of it is found in seeds and rhizomes.
Starch can be classified as follows:
Ground starch is collected from seeds such as corn starch, wheat starch, and underground starch is collected from roots such as cassava starch and sweet potato starch. Starch can also be divided into pure starch and chemically treated starch.
Raw starch unprocessed starch modified starch processed starch
1, modified starch: modified starch is also called "chemical starch" that is, the viscosity, solubility, transparency, coagulation and gelatinization temperature of ordinary starch are improved according to uses and needs, it is a physical or chemical treatment The general name of starch.
With the rapid development of corrugated board manufacturing machines, various modified starches have been researched, and modified starches with high concentration, low viscosity (flow rate) and little drawing have been widely used.
2, the structure of starch
After the cornstarch is dried, the weights of the various ingredients are as follows:
Starch and carbohydrates - 80%
Protein - 10,7%
Grease - 4,5%
Cellulose - 2,5%
Ash - 1%
Impurities - 0, 5%
The composition of other starches is also similar to this. Starch raw materials generally contain about 80% starch, and impurities other than starch are basically eliminated during the starch production process. The starch pure content after starch drying should be above 99%.
(iii) Stein Hall Effect (S-H Law)
The Stein Hall method is a method of preparing a starch adhesive. It consists of three patents obtained by the United States Stayn Hall.
The main contents of the three patents of Steinhoff Law (hereinafter abbreviated SH law) are as follows:
Overflow Device Circulation Device Paste Modulation and Stirring Device This adhesive formulation method is characterized by its skillful use of starch agitation. The general starch adhesives belong to the "solvent evaporation type" which waits until the solvent (water) inside the adhesive is evaporated, and the SH type adhesive is used, not only the solvent evaporation type, but also the adhesive. The physicochemical method to destroy the swellability of starch was added during the process. It can be said that the characteristics of this bonding method are here.
1. Formulation principles of Steinholl method The basic formula of SH-starch binder consists of starch, water base and a small amount of borax. Graphical methods can be expressed as follows:
Carrier Starch Water Base Water Starch Water In addition, borax is sometimes added, but it is not a fundamental ingredient.
The paste liquid formed by combining the above components is called a "double tank system" because it is basically a carrier and a main body that are respectively installed in two slots.
(1) The main purpose of the carrier paste carrier is to transport the starch particles in the body to the exact bonding position.
In the carrier, the starch is completely gelatinized by the action of alkali, so it has a very important role for the main part, specifically:
1 To maintain the viscosity of the paste liquid in a stable state, if the viscosity does not reach a certain level, the starch in the main body portion cannot be evenly applied to the coating roller.
2 To prevent the water in the paste from penetrating too much into the tissue or paper, it is also necessary to control the absorption of the starch in the main body after the starch has fully swollen.
3 In order to contain the water needed for the full swelling of the starch in the body in the carrier.
4 The base in the carrier does not reduce the gelatinization temperature of the starch in the body. There is also the penetration of the main starch into the bonded paper material. The effect of the amount of base used on the gelatinization temperature, but it should be taken into account that the main starch is dissolved and begin to swell in the process of lowering the gelatinization temperature, so there is a limit to the amount of alkali used, otherwise the viscosity of the paste will start to rise. danger.
(2) The role of the body portion of the main body is to finally make the adhesive strength of the corrugated paper reach a predetermined requirement. When the main starch is completely gelatinized by means of the carrier, its function can be exerted. If the starch in the main part is raw starch, its gelatinization temperature is high. To reach 60°C or more, the heat from the hot plate alone is difficult to completely gelatinize. Therefore, it is necessary to add alkali to the carrier as described above. The method is to paste it under low temperature condition, but actually, the gelatinization temperature of the starch in the main part will decrease after increasing the amount of alkali used, and at this time, the gelatinization will occur at a lower temperature, although the corrugated board can be used. The adhesion speed increases, but it is also easy to cause various problems in the paste itself. For example, the paste liquid inside the paste application device, especially on the side of the single-side paper, is affected by the heat of the pressure roller and the corrugating roller, and the paste flow is good and bad, and the local temperature rises to cause gelatinization. It will produce a phenomenon that the paste will clump together, which will make it difficult for the operation.
(a) History of development of corrugated cardboard adhesives
The earliest corrugated cardboard adhesive was sodium silicate. Sodium silicate, also known as water glass, is a very viscous liquid. Its properties generally vary with the ratio of the total molecular weight of silica and sodium oxide. Usually, the ratio of 3:1 to 4:1 is more often used.
The use of sodium silicate-bonded corrugated board offers several advantages over starch-bonded corrugated board. For example, the carton has a high compressive strength, and the shoulder formed by the glue line has a high water resistance.
However, its fatal disadvantage is that it is easy to cause so-called "alkali stain" on the surface of corrugated paper, causing the printing surface to be contaminated, thereby significantly reducing the commercial value of corrugated boxes. The cause of alkali stains is due to the fact that sodium silicate is decomposed by water after absorption of moisture, and the separation of alkali causes deterioration of paper and ink. This change is exacerbated in particular in high-humidity climates. Due to this fatal flaw of sodium silicate, people started to improve on the one hand, and on the other hand, devoted themselves to the development of new adhesives. Of course, the development of new adhesives is also aimed at improving the production efficiency of corrugated board.
The development of semi-chemical pulp and the appearance of kraft face paper have announced that the era of yellow core paper made from wheat straw as the main raw material has come to an end. This new type of noodle paper makes corrugated cardboard move toward high speed and wide width.
In 1956, starch was first introduced into Japan as a binder for corrugated paper, which laid the foundation for the development of modern corrugated paper industry. In this process of transformation, the machinery for producing starch pastes with good performance in agitation has provided a great impetus for the development of the corrugated paper industry in the world.
(b) Starch
Starch is a high-molecular substance that is produced in plants by the combination of carbon dioxide and water and light energy. Usually we call this reaction "photosynthesis."
The plant itself also consumes part of the starch, but it is mainly stored as a chlorophyll and a nutrient source for photosynthesis that are needed to form the next-generation plant. Although starch is found everywhere in plants, most of it is found in seeds and rhizomes.
Starch can be classified as follows:
Ground starch is collected from seeds such as corn starch, wheat starch, and underground starch is collected from roots such as cassava starch and sweet potato starch. Starch can also be divided into pure starch and chemically treated starch.
Raw starch unprocessed starch modified starch processed starch
1, modified starch: modified starch is also called "chemical starch" that is, the viscosity, solubility, transparency, coagulation and gelatinization temperature of ordinary starch are improved according to uses and needs, it is a physical or chemical treatment The general name of starch.
With the rapid development of corrugated board manufacturing machines, various modified starches have been researched, and modified starches with high concentration, low viscosity (flow rate) and little drawing have been widely used.
2, the structure of starch
After the cornstarch is dried, the weights of the various ingredients are as follows:
Starch and carbohydrates - 80%
Protein - 10,7%
Grease - 4,5%
Cellulose - 2,5%
Ash - 1%
Impurities - 0, 5%
The composition of other starches is also similar to this. Starch raw materials generally contain about 80% starch, and impurities other than starch are basically eliminated during the starch production process. The starch pure content after starch drying should be above 99%.
(iii) Stein Hall Effect (S-H Law)
The Stein Hall method is a method of preparing a starch adhesive. It consists of three patents obtained by the United States Stayn Hall.
The main contents of the three patents of Steinhoff Law (hereinafter abbreviated SH law) are as follows:
Overflow Device Circulation Device Paste Modulation and Stirring Device This adhesive formulation method is characterized by its skillful use of starch agitation. The general starch adhesives belong to the "solvent evaporation type" which waits until the solvent (water) inside the adhesive is evaporated, and the SH type adhesive is used, not only the solvent evaporation type, but also the adhesive. The physicochemical method to destroy the swellability of starch was added during the process. It can be said that the characteristics of this bonding method are here.
1. Formulation principles of Steinholl method The basic formula of SH-starch binder consists of starch, water base and a small amount of borax. Graphical methods can be expressed as follows:
Carrier Starch Water Base Water Starch Water In addition, borax is sometimes added, but it is not a fundamental ingredient.
The paste liquid formed by combining the above components is called a "double tank system" because it is basically a carrier and a main body that are respectively installed in two slots.
(1) The main purpose of the carrier paste carrier is to transport the starch particles in the body to the exact bonding position.
In the carrier, the starch is completely gelatinized by the action of alkali, so it has a very important role for the main part, specifically:
1 To maintain the viscosity of the paste liquid in a stable state, if the viscosity does not reach a certain level, the starch in the main body portion cannot be evenly applied to the coating roller.
2 To prevent the water in the paste from penetrating too much into the tissue or paper, it is also necessary to control the absorption of the starch in the main body after the starch has fully swollen.
3 In order to contain the water needed for the full swelling of the starch in the body in the carrier.
4 The base in the carrier does not reduce the gelatinization temperature of the starch in the body. There is also the penetration of the main starch into the bonded paper material. The effect of the amount of base used on the gelatinization temperature, but it should be taken into account that the main starch is dissolved and begin to swell in the process of lowering the gelatinization temperature, so there is a limit to the amount of alkali used, otherwise the viscosity of the paste will start to rise. danger.
(2) The role of the body portion of the main body is to finally make the adhesive strength of the corrugated paper reach a predetermined requirement. When the main starch is completely gelatinized by means of the carrier, its function can be exerted. If the starch in the main part is raw starch, its gelatinization temperature is high. To reach 60°C or more, the heat from the hot plate alone is difficult to completely gelatinize. Therefore, it is necessary to add alkali to the carrier as described above. The method is to paste it under low temperature condition, but actually, the gelatinization temperature of the starch in the main part will decrease after increasing the amount of alkali used, and at this time, the gelatinization will occur at a lower temperature, although the corrugated board can be used. The adhesion speed increases, but it is also easy to cause various problems in the paste itself. For example, the paste liquid inside the paste application device, especially on the side of the single-side paper, is affected by the heat of the pressure roller and the corrugating roller, and the paste flow is good and bad, and the local temperature rises to cause gelatinization. It will produce a phenomenon that the paste will clump together, which will make it difficult for the operation.
(to be continued)
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