Application of puffed corn in adhesive production_SUNSHINE Industry

Puffed corn has been widely used in feed production and food processing. With the deepening of the understanding of puffing technology, a large number of experiments have proved that the effect of using puffed corn as the main raw material to make various adhesives is very satisfactory.

1. Principle

Corn starch contains 27% amylose and 73% amylopectin. Amylose is not a straight chain in an extended state, but curled into a spiral due to the action of intramolecular hydrogen bonds. This tightly packed coil structure of amylose is conducive to the formation of intermolecular hydrogen bonds, but not conducive to the formation of hydrogen bonds with water molecules, so amylose is not easily soluble in cold water. Amylopectin has a highly branched structure, composed of many short chains. Due to the highly branched structure of amylopectin, it is easy to form hydrogen bonds with water molecules, so amylopectin is easily soluble in cold water, but the bonding performance is poor. That is, whether it is amylose or amylopectin, the bonding effect itself is not good, and neither can be used directly as an adhesive. It must be oxidized or gelatinized before it can be used. Gelatinized starch has good initial adhesion and high bonding strength, and can be used directly as an adhesive.

Currently, the gelatinization of starch is mainly heating gelatinization and alkali gelatinization. We chose another gelatinization method: puffing gelatinization, which has good results after trial. According to the principle of puffing, the crushed corn kernels are loaded into the puffing machine, and heated, pressurized and mechanically acted to put the corn in a high temperature and high pressure state. At this time, the sealing cover of the puffing machine is quickly opened. At this moment, because the corn is suddenly reduced to normal temperature and pressure, huge energy is released, and the overheated water vaporizes and evaporates, and its volume can expand by about two thousand times, thereby generating expansion pressure. The huge expansion pressure causes the corn tissue to be subjected to a strong explosion and stretching effect, which makes the corn into countless fine sponge-like structures, that is, the corn is puffed.

After the corn is puffed, the volume of the corn increases several to dozens of times, and it becomes porous, sponge-like, and loose in texture; at the microscopic level, the molecular structure of the internal structure and chemical composition of the corn starch changes, the hydrogen bonds between the starch chains break, the chains move, the starch granules disintegrate, degrade, and α-. During the puffing process, as the starch degrades, part of the side chains of the amylopectin are cut off, that is, the α-1,6 glycosidic bond breaks, and the proportion of shorter straight-chain starch increases. Puffing not only leads to the degradation of amylopectin, but also causes the α-1,4 glycosidic bond in the straight-chain starch to break, producing small molecules, that is, the dextrinization of starch occurs. All these make the hydroxyl groups in the original spiral ring exposed to the outside, which can break the α-1,6 glycosidic bond with water, and increase the proportion of shorter straight-chain starch. Puffing not only leads to the degradation of branched starch, but also causes the breakage of α-1,4 glycosidic bonds in straight-chain starch, producing small molecules, that is, the dextrinization of starch. All these make the hydroxyl groups in the original spiral ring exposed to the outside, which can form hydrogen bonds with water molecules, making the originally insoluble in water become soluble in water. That is, the structure of corn starch after puffing is loose, spongy, and soluble in water. It is soaked and expanded in water, the viscosity increases, the initial adhesion is enhanced, and the bonding strength is significantly improved, which makes the puffed corn starch directly used as an adhesive.

2. Production process

1. Process flow:

Corn → peeling → slag breaking → navel extraction → borax aqueous solution treatment → puffing → crushing → sieving → quality inspection → packaging. The process flow can be adjusted according to the actual situation. If corn starch is used for production, the process flow is simplified to: corn starch → borax aqueous solution treatment → puffing → crushing → sieving → quality inspection → packaging.

2. Key points of operation

Take clean corn, peel, break slag, extract corn germ, and make corn crumbs. The quality should be skinless and navelless. Put the corn crumbs directly into the puffing machine for puffing. After puffing, crush them with a crusher at any time, sieve, and collect 200 mesh fine powder to obtain puffed corn starch. 70 kg of puffed corn starch can be obtained from every 100 kg of corn.

3. Application

1. Wallpaper glue powder

Wallpaper adhesive used to use white latex, but its use in winter is limited due to its poor frost resistance. Now there are various wallpaper adhesives, which have good bonding effects, but high costs. If puffed corn starch is used to prepare wallpaper adhesive, it has good bonding effects, low costs and is easy to use.

Formula (mass fraction):

Puffed corn starch, 0.96; salicylic acid, 0.02; sodium pentachlorophenol, 0.01; sodium diacetate, 0.01.

Mix evenly, sieve and package to get the finished product.

Usage:

Take 1 kg of wallpaper glue powder, add 1 kg of cold water, stir evenly to get a paste wallpaper glue. It can be adjusted as needed, and it is very convenient to use. The product can be stored for a long time. The wallpaper it bonds is smooth, has good initial adhesion, does not warp, does not change color, and will not be eaten by insects.

2. Corrugated cardboard adhesive powder

In the past, corrugated cardboard was bonded with sodium silicate, because it is easy to get damp and toxic. Now it has been replaced by corn starch adhesive in many places. Corn starch adhesive is light in weight, has high bonding strength, and is non-toxic, but its natural drying speed is too slow, which limits its general application. The expanded corn starch adhesive has good initial bonding performance, high bonding strength, fast drying speed, and is easy to use. Formula (mass fraction): expanded corn starch, 0.83; potassium permanganate, 0.02; sodium hexametaphosphate, 0.02; sodium benzoate, 0.03; sodium bentonite, 0.10. After mixing evenly, sieve and package to obtain the finished product. Usage: Take 1 kg of corrugated box adhesive powder and add 5 kg of cold water. Stir well and then use. The usage is the same as that of caustic soda. The adhesive has good flow rate, no glue throwing, no edge running, no corrosion, and no toxicity. The next process can be carried out in 6 hours. It has no burrs, no collapse, high hardness, light weight, and high bonding strength.

3. Oilfield additives

The water-soluble polymers used in oil fields are mainly carboxymethyl cellulose, carboxymethyl starch, polyacrylamide, polyacrylic acid, etc. They play an important role in inhibiting scale in oil fields, plugging water in oil fields, and increasing oil production. Because puffed corn starch is easy to dissolve, has high viscosity, is resistant to high temperatures, and has low cost, it is an ideal substitute for the above products.

Formula (mass fraction):

Puffed corn starch, 0.75; sodium hexametaphosphate, 0.05; polyacrylamide, 0.07; sodium benzoate, 0.03; calcium-based bentonite, 0.10.

Mix evenly, sieve, and package to obtain the finished product.

Usage:

Take 1 kg of oilfield additive powder, add 4 kg of cold water, stir evenly, and inject it into the well with a pump. The price of this additive can be much lower than that of carboxymethyl cellulose. Due to its high viscosity and strong ability to absorb mud, it can significantly increase crude oil production.

4. Textile sizing powder

Textile sizing used to use starch solution, which was used by direct heating. It is labor-intensive and time-consuming and consumes a lot of energy. Now a mixture of starch and polyvinyl alcohol is mostly used. Because it is heated, it brings certain inconvenience to the application. Puffed corn starch can be dissolved by adding cold water, which saves time, labor, energy and is very convenient to use.

Formula (mass fraction):

Puffed corn starch, 0.85; sodium tripolyphosphate, 0.05; oxidized polyethylene wax, 0.08; sodium benzoate, 0.02.

After mixing evenly, sieve and package to get the finished product.

Usage:

Take 1 kg of textile slurry powder, add 20 kg of cold water, stir evenly and use it. The usage is the same as general textile slurry. Because the slurry produces a line with appropriate hardness and softness, it feels good and the yarn breakage rate is significantly reduced.