The use of starch binders to replace the long-established alkaline binder silicate (ie, sodium silicate, also known as water glass), is a major improvement in the production of China's carton industry.
Advantages of corn starch adhesive are: simple production equipment, convenient production, quick production, bonding strength is higher than about 10% of basaltic alkali, moisture resistance is also better than scouring alkali adhesive, and coating amount and cost Lower than the buccal alkali adhesive. Corrugated paper packaging containers produced with scolated alkali binders have a longer storage time, and they tend to absorb moisture and efflorescence, causing cracking of the containers due to weakness, resulting in moldy, rusting, and undue loss of the interior products. The quality of corrugated cardboard and containers made with corn starch binders has been significantly improved, and it has been adapted to the needs of foreign trade.
Adhesives made from corn starch include hydrochloric acid hydrolysis, oxidation, cooking, and cooling. Here is the most commonly used oxidation method.
First, raw materials
1, corn starch: use a product.
2, sodium hydroxide (NaOH): also known as caustic soda, caustic soda, caustic soda. The pure product is a white transparent crystal with a relative density of 2.130 and a melting point of 318.4°C. Industrial products contain a small amount of sodium chloride and sodium carbonate, which are white opaque solids, and are in the form of flakes, lumps, granules, and rods. Very hygroscopic, soluble in water, and strongly exothermic. It is a strong base and is highly corrosive to skin, fabrics, and paper. Corrosion-resistant containers, such as glass, ceramics, and Plastic Containers, must not be used in the preparation of solutions. Operators must wear protective gloves and should be flushed quickly with water when splashed on the skin or clothing. Solid materials need to be moisture-proof when stored. Here as starch gelatinizer. Use industrial products.
3, hydrogen peroxide (H2O2): Common name hydrogen peroxide. The pure product is a colorless liquid that is heavier than water and has a relative density of 1.438. Commercially available are generally 3% and 30% aqueous solutions. It can be mixed with water, ethanol or ether in any ratio. It will be decomposed into oxygen and water during storage. Stabilizers are generally added to prevent decomposition. Here as an oxidant, use industrial products.
4, borax (Na2B4O7 · 10H2O): scientific name sodium tetraborate, a colorless translucent crystal or white monoclinic crystal powder. Odorless, salty. The relative density is 1.73, eight crystal waters are lost at 60°C, and all crystal waters are lost at 350 to 400°C. Soluble in water, glycerol, slightly soluble in alcohol, aqueous solution is weakly alkaline. It can be slowly weathered in the air and becomes a colorless glassy substance when melted. A bactericidal effect. Here as a bactericidal preservative. Use industrial products.
5, sulfur dioxide (SO2): also known as thionine anhydride. Colorless gas with pungent odor. It can be liquefied into a colorless liquid at room temperature under pressure of 4 atm, with a relative density of 1.434 (0°C) and a boiling point of -10°C. When dissolved in water, it turns into sulfurous acid, which is also soluble in ethanol and ether. Here about 0. 2% of sulfur dioxide solution is used to soak corn. Production plants: Dalian Chemical Plant, Jilin Chemical Industry Company Dyestuff Factory and Nanjing Chemical Industry Company Nitrogen Fertilizer Plant.
6, defoamer: In the production process will appear a certain degree of blistering, you can add the right amount of defoamer. For example, silicone oil, tributyl phosphate and the like.
Second, the preparation method
1, corn starch production:
Starch production is the process of separating non-starch material plus protein, cellulose, oils and fats from starch. The degree of separation of each component is related to the process method used. Nowadays, the simple production methods adopted in industry still cannot completely separate non-starch materials, but because the proportion of starch in the starch is very small, it does not affect the application of starch. The most common production method currently used is the wet production of corn starch. The principle is based on two important properties of starch in water: one is insoluble in cold water, and the other is that the density is greater than water. The yield varies depending on the corn variety, which is generally 65-68% for silty corn, 62-65% for horse tooth corn, and 60-63% for hard-shelled corn.
The steps for wet corn starch production are as follows:
(1) Soaking: Soak the corn kernels in the soaking bucket and soak them with about 0.2% sulfur dioxide solution. This step has a direct effect on the yield and quality of the product. The purpose of soaking, in addition to softening the granules, can also disrupt or weaken the connections between the various components of the corn, disperse the protein network in the endoderm cells, and separate the starch and non-starch fractions to remove most of the soluble matter. Soaking temperature should be controlled at 48 ~ 50 °C, if the temperature is too high, the protein will denature. Throughout the soaking process, temperature stability should be maintained as much as possible to produce a good soaking effect. The soaking time is generally between 45 and 50 hours, and the yellow hard-coated corn is about 70 hours. The determination of the length of time shall take into account the water absorption of corn kernels and the leaching of other substances. The soaked corn granules are squeezed with the fingers and the germ can be detached. The starch is easily decomposed, the moisture content is 40-46%, and the soluble matter is not more than 2.5%. When soaking to the required degree, the water will be released. Generally, about 1000 to 1500 liters of water will be released per ton of corn, and each time of soaking, it will be replaced with new water.
(2) Fragmentation and separation of germ: After immersed corn is crushed by a mill or a crusher, the germ is then separated from the tank, water is added to make the germ float on the water, and the germ is separated. Two crushing and two embryo separations are generally used. For the first time of crushing, the consistency of the material is controlled at 250-300 g dry matter/liter. From this diluted solution, more than 70% of the germs can be separated; for the second crushing, the consistency is controlled at 75 g dry matter/liter, and the relative density is 1.03 to 1.06.
(3) Separation and washing of fibers: After the embryos are separated, the slurry is ground to separate the fibrous corn slag and separate the starch from the protein granules in the keratinocyte endoderm. The fibrous residue is then sieved and washed with a sieve. ,Recovering starch. The purpose of grinding is to destroy the corn cell tissue, free the starch granules, and separate the fibers and bran. Generally, it is ground twice and broken once with a hammer mill. Then the starch milk is sifted out to remove fiber and bran. The second time, the ground is ground again with a grinding mill. The ground maize paste is sieved. Separate starch and coarse slag. Generally, it is advisable to control the slurry and the consistency of the slurry to be 190 to 200 g dry matter/liter, so as to ensure the grinding effect. Screens generally use a sieve of 100 to 140 mesh. The slag after sieving needs to be washed, and the amount of water used is calculated as 100 kg of dry corn. They are: 230 to 250 liters of coarse slag, 110 to 130 liters of fine slag, and 100 to 120 liters of germ. The temperature of the washing water is 45-55°C, the concentration of sulfur dioxide is 0.05%, and the pH is 4.3-4.5.
(4) Starch milk refinement: The starch milk obtained after the above treatment still contains protein, fiber and other impurities, which need to be further refined. That is, the starch milk is passed through the flow tank to remove solubles and insoluble matters, so that the starch and gluten are produced. Fine residue separated. The principle of separation is to use different gluten water of relative density and particle size of each component to flow along with the protein, and the starch settles on the chute, and then it is transported by water to flush it to the storage tank for use. The separated gluten water is concentrated to produce protein powder.
The length of the runner is generally 20 to 40 meters. The settlement of the starch on the chute is a certain slope, the thickest at 2 to 3 meters, the thickness is controlled at 125 to 130 mm, and the thickness is not more than 150 mm. Otherwise, the slope is too large and there is a lot of starch loss.
The temperature is preferably 37-38°C, generally not lower than 30°C. If the temperature is higher than 38°C, the starch is not tight and the loss increases. The concentration of starch milk is preferably 10-13°C. The starch quality after sinking is about 50% moisture and about 0.6 to 1% protein.
(5) Dehydration and drying: The obtained refined starch milk is sent to a centrifugal centrifuge and dehydrated to obtain wet starch (moisture content: about 45%). The dehydration temperature is preferably 35 to 40°C. Then use vacuum or air drying to control the drying temperature below 70°C. During the drying process, some dry materials can be properly added to prevent local moisture from being caused by excessive moisture during the drying process.
(6) Screening and packaging: When necessary, the dried starch must be sieved through 100 mesh. The coarse starch is then crushed. After the fineness reaches the requirements, the finished product is packaged.
The quality of corn starch should meet the following requirements:
Appearance white or light yellow shade powder moisture (%) ≤14
Protein (%) ≤ 0.5
Ash Content (%) ≤ 0.1
Acidity (consumption of 0.1 mol/l NaOH ml per 100 g dry starch) ≤ 20
Fineness (100 mesh) (%) ≥98
(to be continued)
Advantages of corn starch adhesive are: simple production equipment, convenient production, quick production, bonding strength is higher than about 10% of basaltic alkali, moisture resistance is also better than scouring alkali adhesive, and coating amount and cost Lower than the buccal alkali adhesive. Corrugated paper packaging containers produced with scolated alkali binders have a longer storage time, and they tend to absorb moisture and efflorescence, causing cracking of the containers due to weakness, resulting in moldy, rusting, and undue loss of the interior products. The quality of corrugated cardboard and containers made with corn starch binders has been significantly improved, and it has been adapted to the needs of foreign trade.
Adhesives made from corn starch include hydrochloric acid hydrolysis, oxidation, cooking, and cooling. Here is the most commonly used oxidation method.
First, raw materials
1, corn starch: use a product.
2, sodium hydroxide (NaOH): also known as caustic soda, caustic soda, caustic soda. The pure product is a white transparent crystal with a relative density of 2.130 and a melting point of 318.4°C. Industrial products contain a small amount of sodium chloride and sodium carbonate, which are white opaque solids, and are in the form of flakes, lumps, granules, and rods. Very hygroscopic, soluble in water, and strongly exothermic. It is a strong base and is highly corrosive to skin, fabrics, and paper. Corrosion-resistant containers, such as glass, ceramics, and Plastic Containers, must not be used in the preparation of solutions. Operators must wear protective gloves and should be flushed quickly with water when splashed on the skin or clothing. Solid materials need to be moisture-proof when stored. Here as starch gelatinizer. Use industrial products.
3, hydrogen peroxide (H2O2): Common name hydrogen peroxide. The pure product is a colorless liquid that is heavier than water and has a relative density of 1.438. Commercially available are generally 3% and 30% aqueous solutions. It can be mixed with water, ethanol or ether in any ratio. It will be decomposed into oxygen and water during storage. Stabilizers are generally added to prevent decomposition. Here as an oxidant, use industrial products.
4, borax (Na2B4O7 · 10H2O): scientific name sodium tetraborate, a colorless translucent crystal or white monoclinic crystal powder. Odorless, salty. The relative density is 1.73, eight crystal waters are lost at 60°C, and all crystal waters are lost at 350 to 400°C. Soluble in water, glycerol, slightly soluble in alcohol, aqueous solution is weakly alkaline. It can be slowly weathered in the air and becomes a colorless glassy substance when melted. A bactericidal effect. Here as a bactericidal preservative. Use industrial products.
5, sulfur dioxide (SO2): also known as thionine anhydride. Colorless gas with pungent odor. It can be liquefied into a colorless liquid at room temperature under pressure of 4 atm, with a relative density of 1.434 (0°C) and a boiling point of -10°C. When dissolved in water, it turns into sulfurous acid, which is also soluble in ethanol and ether. Here about 0. 2% of sulfur dioxide solution is used to soak corn. Production plants: Dalian Chemical Plant, Jilin Chemical Industry Company Dyestuff Factory and Nanjing Chemical Industry Company Nitrogen Fertilizer Plant.
6, defoamer: In the production process will appear a certain degree of blistering, you can add the right amount of defoamer. For example, silicone oil, tributyl phosphate and the like.
Second, the preparation method
1, corn starch production:
Starch production is the process of separating non-starch material plus protein, cellulose, oils and fats from starch. The degree of separation of each component is related to the process method used. Nowadays, the simple production methods adopted in industry still cannot completely separate non-starch materials, but because the proportion of starch in the starch is very small, it does not affect the application of starch. The most common production method currently used is the wet production of corn starch. The principle is based on two important properties of starch in water: one is insoluble in cold water, and the other is that the density is greater than water. The yield varies depending on the corn variety, which is generally 65-68% for silty corn, 62-65% for horse tooth corn, and 60-63% for hard-shelled corn.
The steps for wet corn starch production are as follows:
(1) Soaking: Soak the corn kernels in the soaking bucket and soak them with about 0.2% sulfur dioxide solution. This step has a direct effect on the yield and quality of the product. The purpose of soaking, in addition to softening the granules, can also disrupt or weaken the connections between the various components of the corn, disperse the protein network in the endoderm cells, and separate the starch and non-starch fractions to remove most of the soluble matter. Soaking temperature should be controlled at 48 ~ 50 °C, if the temperature is too high, the protein will denature. Throughout the soaking process, temperature stability should be maintained as much as possible to produce a good soaking effect. The soaking time is generally between 45 and 50 hours, and the yellow hard-coated corn is about 70 hours. The determination of the length of time shall take into account the water absorption of corn kernels and the leaching of other substances. The soaked corn granules are squeezed with the fingers and the germ can be detached. The starch is easily decomposed, the moisture content is 40-46%, and the soluble matter is not more than 2.5%. When soaking to the required degree, the water will be released. Generally, about 1000 to 1500 liters of water will be released per ton of corn, and each time of soaking, it will be replaced with new water.
(2) Fragmentation and separation of germ: After immersed corn is crushed by a mill or a crusher, the germ is then separated from the tank, water is added to make the germ float on the water, and the germ is separated. Two crushing and two embryo separations are generally used. For the first time of crushing, the consistency of the material is controlled at 250-300 g dry matter/liter. From this diluted solution, more than 70% of the germs can be separated; for the second crushing, the consistency is controlled at 75 g dry matter/liter, and the relative density is 1.03 to 1.06.
(3) Separation and washing of fibers: After the embryos are separated, the slurry is ground to separate the fibrous corn slag and separate the starch from the protein granules in the keratinocyte endoderm. The fibrous residue is then sieved and washed with a sieve. ,Recovering starch. The purpose of grinding is to destroy the corn cell tissue, free the starch granules, and separate the fibers and bran. Generally, it is ground twice and broken once with a hammer mill. Then the starch milk is sifted out to remove fiber and bran. The second time, the ground is ground again with a grinding mill. The ground maize paste is sieved. Separate starch and coarse slag. Generally, it is advisable to control the slurry and the consistency of the slurry to be 190 to 200 g dry matter/liter, so as to ensure the grinding effect. Screens generally use a sieve of 100 to 140 mesh. The slag after sieving needs to be washed, and the amount of water used is calculated as 100 kg of dry corn. They are: 230 to 250 liters of coarse slag, 110 to 130 liters of fine slag, and 100 to 120 liters of germ. The temperature of the washing water is 45-55°C, the concentration of sulfur dioxide is 0.05%, and the pH is 4.3-4.5.
(4) Starch milk refinement: The starch milk obtained after the above treatment still contains protein, fiber and other impurities, which need to be further refined. That is, the starch milk is passed through the flow tank to remove solubles and insoluble matters, so that the starch and gluten are produced. Fine residue separated. The principle of separation is to use different gluten water of relative density and particle size of each component to flow along with the protein, and the starch settles on the chute, and then it is transported by water to flush it to the storage tank for use. The separated gluten water is concentrated to produce protein powder.
The length of the runner is generally 20 to 40 meters. The settlement of the starch on the chute is a certain slope, the thickest at 2 to 3 meters, the thickness is controlled at 125 to 130 mm, and the thickness is not more than 150 mm. Otherwise, the slope is too large and there is a lot of starch loss.
The temperature is preferably 37-38°C, generally not lower than 30°C. If the temperature is higher than 38°C, the starch is not tight and the loss increases. The concentration of starch milk is preferably 10-13°C. The starch quality after sinking is about 50% moisture and about 0.6 to 1% protein.
(5) Dehydration and drying: The obtained refined starch milk is sent to a centrifugal centrifuge and dehydrated to obtain wet starch (moisture content: about 45%). The dehydration temperature is preferably 35 to 40°C. Then use vacuum or air drying to control the drying temperature below 70°C. During the drying process, some dry materials can be properly added to prevent local moisture from being caused by excessive moisture during the drying process.
(6) Screening and packaging: When necessary, the dried starch must be sieved through 100 mesh. The coarse starch is then crushed. After the fineness reaches the requirements, the finished product is packaged.
The quality of corn starch should meet the following requirements:
Appearance white or light yellow shade powder moisture (%) ≤14
Protein (%) ≤ 0.5
Ash Content (%) ≤ 0.1
Acidity (consumption of 0.1 mol/l NaOH ml per 100 g dry starch) ≤ 20
Fineness (100 mesh) (%) ≥98
(to be continued)
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