Production mechanism and application of the hottes

Production mechanism and application of corrugated board starch adhesive

corrugated board starch adhesive is a bonding material that firmly bonds corrugated paper with face paper or sandwich paper to form corrugated board. Its bonding performance has a direct impact on the bursting strength, edge compression strength, puncture strength and compressive strength of corrugated board and carton, and is a key factor related to the quality of corrugated board and carton

pure starch is a white polysaccharide powder with a particle diameter of about 4-50um, which is insoluble in cold water and has no viscosity. Using starch as paperboard bonding material, we must change the granular structure of starch by heating and adding other chemical substances, make it swell and disperse in water, change the physical and chemical properties of starch, improve the affinity between starch molecules and paper fibers, and improve the fluidity and permeability of starch colloid, so as to meet the requirements of corrugated paperboard production process. Up to now, the production methods of starch adhesives that have been developed and applied include: direct heating method, alkali paste method, dextrin method, oxidation method, stilbene modulation method, etc. Because the direct heating starch adhesive is only suitable for manual coating, and the adhesive strength of alkali paste starch adhesive is poor, it is rarely used now. This paper will briefly describe the production mechanism of partial dextrin, oxidized starch, and the production mechanism of stiinher modulation starch adhesive, and briefly introduce the widely used stiinher modulation starch adhesive, in order to further study and improve the packaging bonding process Materials for reference

production mechanism of oxidized starch

the molecular structure of dextrin is the same as that of starch, and its affinity with paper fiber is not very strong, and dextrin is a good feed for bacteria, and its anti-corrosion and anti mildew ability is poor, while oxidized starch shows good affinity between colloid and paper fiber, and its production mechanism is as follows:

starch is made from α－ The macromolecular carbohydrate formed by dehydration and condensation of glucose has a glycoside hydroxyl at the end of its molecular chain, and the rest are secondary alcohol group and primary alcohol group. Because the molecular chain of starch is long and the molecular weight is large, the role of a small amount of glycoside hydroxyl is insignificant, so there is no reducibility like glucose molecule, neither can there be mirror reaction, nor can copper hydroxide be reduced to cuprous oxide. People usually add an appropriate amount of sodium hydroxide solution to the lotion of starch to make oxidized starch. Sodium hydroxide combines with the alcohol group in the starch molecule, destroying part of the hydrogen chain and weakening the interaction between macromolecules. At the same time, a strong oxidant of hydrogen peroxide (or sodium hypochlorite, sodium oxide, potassium permanganate) is added to the lotion. When hydrogen peroxide is dissolved in water, hydrogen peroxide ion H02 (or hypochlorite ion cl0-, permanganate ion mn04) with strong oxidation will be produced. This kind of ionizer with strong oxidation can oxidize the glycoside hydroxyl at the end of starch molecule to carboxyl group, oxidize the primary alcohol group to aldehyde group, and even further oxidize it to carboxyl group, Thus, the vitality of starch molecules is greatly enhanced, the chain of starch molecules is broken from the glucoside chain position (i.e. 1.4 carbon position), and the starch molecular chain is shortened and the molecular weight is reduced. After chain breaking, the newly generated glycoside hydroxyl will continue to be oxidized to carboxyl. In this way, the glycoside carboxyl of starch molecules will be oxidized to carboxyl, and then the glycoside chain will be broken. New glycoside hydroxyl will appear, and the new glycoside hydroxyl will be oxidized to carboxyl. This reaction continues, making the starch molecular chain shorter and shorter, and the carboxyl and aldehyde groups will continue to increase. When the carboxyl and aldehyde groups in the starch lotion reach a certain concentration, it will have sufficient affinity for paper fibers, And have enough anti-corrosion and mildew resistance. However, in practical application, the concentration of carboxyl and aldehyde groups must be controlled. The concentration is too low, the anti-corrosion ability is poor, and the affinity with paper fiber is not strong. If the concentration is too high, it means that the long molecular chain of starch is broken into very short molecular chains. Although it has strong affinity with paper fiber, due to the short molecular chain, the interweaving coefficient between starch molecules becomes smaller, the force between molecules becomes smaller, and the toughness and strength of bonding film decrease. Therefore, people usually want to control the degree of starch oxidation. The way to do is to control the dosage of oxidant, oxidation temperature and reaction time

oxidized starch is the functional group of oxidized starch molecule, which improves its affinity with paper fiber and its anti-corrosion and anti mildew ability. During the oxidation process, starch molecule breaks chain and its molecular weight becomes smaller. Therefore, oxidized starch is also called dextrin by foreign people. It should be noted that the functional group of oxidized starch is different from that of starch, while the functional group of dextrin is exactly the same as that of starch, so it is different from that of paper fiber in terms of affinity, anti-corrosion and anti-corrosion. Strictly speaking, it is more accurate to call oxidized starch oxidized dextrin, but in view of people's traditional habits, it is still appropriate to call it oxidized starch

the production mechanism and application of stieher starch adhesive

the common shortcomings of alkali paste method, dextrin method and oxidation method starch adhesive are large water volume and low solid content in colloid, which are not suitable for the production process requirements of high-speed coating, instantaneous bonding and rapid drying of modern corrugated board production line. Si tuiher put forward the modulation method, which can increase the starch concentration, not damage the length of starch chain, and not increase the viscosity of starch colloid, which meets the special production process requirements of corrugated board production lines. This method has been widely used in corrugated board production lines in various countries. Now, the production mechanism and application of Si tuiher modulation starch adhesive are briefly introduced

(I) production mechanism of starch adhesive prepared by stieher

gelatinize water, starch and sodium hydroxide into carrier adhesive in a certain proportion in one tank, while stirring starch, borax and water into main starch solution in a certain proportion in another tank, and then mix the two evenly. Its production mechanism is that a small amount of starch is used to gelatinize into a carrier glue with high viscosity, and a large number of main starch particles without gelatinization, viscosity and small volume are adsorbed and dispersed in the colloid, which is conducive to increasing the concentration of starch, reducing the amount of water, not damaging the starch chain, and not improving the overall viscosity of the colloid, so that the fluidity, permeability and bonding strength of the colloid can achieve a good comprehensive effect. Sodium hydroxide can adjust and control the gelatinization temperature of starch adhesive and improve the hydrophilicity of starch, while borax can complex the glycoside hydroxyl and primary alcohol groups of starch molecules to enhance the initial viscosity and conjunctival toughness of the adhesive. In the production process, the colloid with good fluidity is coated on the corrugated peak, which is heated to above the gelatinization temperature after bonding with the face paper and sandwich paper. The main starch quickly absorbs the surrounding water and gelatinizes, producing extremely high viscosity. In particular, the small main starch particles that penetrate into the gap of paper fibers will gelatinize from the gap of paper fibers after heating and interweave with the peripheral starch molecules, paper fibers, and boron oxygen central ions to form different general filled bonding layers. With the rapid increase of heat, water will soon evaporate into the atmosphere, or diffuse into the paper fibers, and the starch colloid will dry into a tough bonding film with less water, Therefore, corrugated paper and face paper or sandwich paper are firmly bonded together to form corrugated board

(II) application examples of starch adhesives prepared by stieher

there are many kinds of starch adhesives prepared by stieher, but they can be divided into hot method and cold method according to the production temperature. In addition, Zhuzhou foreign trade packaging factory has developed a Y-type water-resistant reinforcement additive, which is added to the adhesive to make a water-resistant adhesive, The corrugated board has better water resistance and mechanical strength. Now one example is introduced to save money

1. application example of hot method

(1) preparation of carrier glue

a. heat 432l water to 62 ℃ and inject it into the carrier tank

b. pour 62.5kg starch into the carrier tank and stir it into starch milk

c. add 62.5kg of 20% sodium hydroxide solution into the carrier tank and stir for 15 minutes until the colloid is light yellow

d. inject 1.78l of water into the carrier tank and stir for 5 minutes to dilute

② main body milk production

a. heat 1327l water to 32 ℃ and inject it into the main body tank

b. add 9.5kg borax into the main tank. C. Add 400kg starch into the main tank and stir for 15 minutes

③ mixing and modulation

inject the carrier glue into the main tank for 15 minutes and stir for 30 minutes to become the finished glue

2. There should be examples of cold method

① the production of carrier glue can also meet the aesthetic needs of consumers for the appearance of products

a. add 320kg of water to the carrier tank

b. add 30kg starch into the carrier tank and stir it into a lotion

c. add 24.5kg of 20% sodium hydroxide solution into the carrier cylinder and stir for 15 minutes until the colloid is light yellow

② main body milk production

a) inject 420kg of water into the main body tank

b) add 150kg starch into the main tank and stir it into lotion

c) add 3.7kg borax (10 water borax) into the main tank and stir for 5 minutes

③ mixing and modulation

inject the carrier glue into the main tank with 5 minutes, and stir for 25 minutes to become the finished glue

3. Application examples of water-resistant adhesive

① production of carrier adhesive

a. add 350kg of water to the carrier tank

b. add 25kg starch into the carrier tank and stir it into lotion

c. add 15kg of 30% sodium hydroxide into the carrier tank and stir for 15 minutes until the colloid turns pale yellow

② main body milk production

a. add 350kg of water to the main body tank

b. add 3kg borax (10 water borax) into the main tank

c. add 150kg starch into the main tank and stir it into lotion

d. add 1.8L of Y-type additive into the main tank and stir for 2 minutes to disperse it evenly

③ mixing production

inject the carrier glue into the main tank for 5 minutes and stir for 30 minutes to form the finished glue

it should be specially pointed out that Dian can be said to be the winner in the automotive field today. There are many methods of making baby powder adhesives, and the adhesive formula suitable for various materials and production process conditions is not invariable. Due to space limitations, this article only gives a brief introduction

technical know-how of starch adhesive production in automatic paperboard production line (or single-sided machine)

at present, the adhesives used in automatic paperboard production lines (or single-sided machines) at home and abroad are commonly known as "raw glue". The so-called "raw glue" means that there is no adhesive force at room temperature, and only when it is heated into mature glue by the high temperature on the paper can it have adhesive force. The preparation method mainly uses starch (mainly corn starch, but also cassava starch, wheat starch and other starch), and the adhesive is prepared by two-step method. The disadvantages of this kind of pure starch adhesive are: the strength and hardness of the produced paperboard are not high, the moisture-proof performance is poor, and it is not water-resistant

the best viscosity of adhesive in automatic paperboard production line (or single-sided machine) should be controlled between 45-95 seconds (measured by coating 4 cups), of course, it can also be used between 30-300 seconds, which is actually