Characteristics of hottest starch and its research

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The characteristics of starch and its research and application in the packaging industry

Abstract] this paper introduces the characteristics of starch, summarizes the research of starch and its application in the packaging industry, points out the gap between the current performance of starch and foreign countries, and emphasizes the importance of strengthening the research of special starch

key words: starch; characteristic; Research; Application; Packaging industry

starch is a renewable natural polymer compound with good adhesion and film-forming properties. The deep processing of corn starch to prepare various fine chemical products has attracted people's attention. People have done a lot of research work in the process and application of starch modification, preparation and production of various adhesives. Starch is a kind of water-soluble compound with low price, rich source of raw materials and non-toxic, which has been widely used in packaging and other industries

1 research on starch and its application in packaging

1.1 packaging adhesive

starch adhesive is a kind of water-soluble adhesive with low price, rich source of raw materials and no toxicity. Now it plays a very important role in the whole packaging paper container material and corrugated board. Almost all the corrugated board produced is cemented by starch based adhesives, and oxidized starch adhesive because of its excellent performance, It is widely used in the corrugated board production of single-sided machine. However, the viscosity of starch adhesive is unstable, which affects its bonding performance. In order to improve its adhesive properties, Zhang Qinfa et al. Studied in detail the factors affecting the viscosity of oxidized starch adhesive. The results show that when the amount of oxidant (based on the quality of starch) is 18%~24%, the amount of sodium hydroxide is 1.6%~2.6%, m (water):m (starch) =4.5:5.5, the oxidation time is 15~25min, and the oxidation temperature is 20~30 ℃, the adhesive has better performance and is suitable for the bonding of corrugated paper. It is also found that the adhesive prepared with potassium permanganate as oxidant is relatively stable in closed containers

starch adhesive has also been used in the carrier of corrugated board, but because the traditional corrugated board uses alkali in the production process, it is easy to return to moisture. In order to overcome this shortcoming, helunying et al. Studied the modification of carrier starch adhesive with H, P, Q, W and other substances respectively. Through screening test and comprehensive analysis, the optimal formula of the amount of composite additive was determined. The results showed that when the amount of composite additive (based on the mass% of starch) was 11% - 12%, and the amount of sodium hydroxide was 32%, the adhesive had good fluidity, suitable viscosity, and good water retention performance, It can completely and evenly infiltrate the surface of the adherend, and has strong bonding ability; The addition of multifunctional additives can improve the stability of the adhesive, the difficulty of delamination, gel and decay, and the cost is low. The corrugated board produced by the modified carrier starch adhesive has high bonding strength, low moisture regain and good stiffness. Suitable for corrugated boxes for refrigerated food

plastic products have been widely used in the packaging industry. However, at present, the adhesive used for trademark paper pasting of plastic packaging containers has poor pasting effect. It often falls off after pasting and drying. It lacks sufficient affinity for plastic, has high cost, and has great toxic pollution. For example, solvent based adhesives such as polyacrylic acid and polyurethane, although they stick firmly, they are absolutely prohibited from use in the food and beverage industry due to high cost and toxic pollution. Zeng Defang and others synthesized a green adhesive by using polyacrylic acid modified starch and adding composite additives. Water soluble acrylic agent B was selected. It was found that the addition of agent B not only enhanced the bonding strength with the plastic surface, but also improved the bonding strength of the whole starch adhesive. Auxiliary agent a is prepared from several alcohols, which improves the miscibility of auxiliary agent B and starch glue. It is a good cosolvent, and also has the function of wetting and antifreeze. Compared with similar products, this adhesive has the advantages of non-toxic, pollution-free and good adhesion. It is widely used in trademark bonding in plastic packaging industry

1.2 2. Basic properties of fillers modified starch packaging film

nowadays, polyethylene, cellophane and man-made fibers are the most commonly used food packaging materials at home and abroad. They cannot be degraded in nature. These packaging wastes pollute the environment. On the other hand, the mechanical strength of edible films is insufficient. In order to overcome these shortcomings, many scholars at home and abroad have conducted research in this area. Li Zhida and other starch materials with amylose content of about 80% separated by physical and chemical methods and isoamylase modified starch (amylose content of about 40%), and added additives to study their film-forming properties. Experiments show that sorbitol and glycerol are good edible plasticizers, CMC Na is a good strength enhancer, and animal protein hydrolysate can solve the problem of Film Uncovering. Through the reaction, a kind of edible starch film with good tensile properties, transparency and folding resistance was obtained, which has a broad development prospect in food packaging

starch is a hydrophilic substance with strong polarity, while LDPE is a hydrophobic substance with very small polarity. The structure and polarity of the two are very different. In order to improve the filling amount of starch and make the starch evenly distributed in LDPE, it is necessary to modify the starch. Zhang Huaji used oxidized polyethylene (OPE) as compatibilizer of starch filled LDPE Blend System, and self-made cerium octanoate, cerium laurate and cerium stearate as photodegradation accelerator of starch filled LDPE Blend System to develop degradable LDPE masterbatch and film. The composition of starch/stearic acid persimmon blend system was studied. The hydrophobic treatment of starch by aluminate, the compatibilization of oxidized polyethylene to starch/LDPE Blend System, and the effect of cerium stearate on the base index of photooxidative degradation of LDPE were discussed. The performance and application tests of LDPE coated films containing 20% starch and 0.4% cerium stearate were carried out. The results showed that its mechanical and sanitary properties met the requirements of national standards. After being buried for one year, it degraded into fragments less than 25cm, which were gradually assimilated by soil, reducing environmental pollution

1.3 all starch plastic packaging

with the enhancement of environmental awareness, all countries are developing environmental friendly packaging materials. At present, starch degradation resin and all starch thermoplastic have achieved certain results

the so-called starch degradation resin is the blending of biomaterial starch and degradation accelerator with synthetic resin. Under the action of microorganism, high temperature and oxygen, the high molecular chain in plastic breaks, the molecular weight decreases, and finally it is transformed into CO2, water and bioorganics. The development and use of this kind of resin can partially solve the pollution caused by plastics. All starch plastic is a plastic made of starch and a small amount of degradable plasticizers. It can be completely biodegradable without pollution after use. The research progress of all starch plastic is very fast, and it is especially suitable for the packaging of food, medicine, health and other aspects. Because it does not meet the standard requirements at present, all countries have strengthened the research in this field. From the current research situation, all starch plastic is better used in extrusion blow molding, but it can only produce 20 μ M above, the stability of injection molded hard products is good. However, there are still some defects in the application of bottle blowing, calendering sheet, vacuum blister and so on, such as low pressure resistance, poor toughness, fragile and so on

in addition, starch based fully biodegradable plastics have developed rapidly and achieved many industrialization results. In order to improve the blending compatibility between starch and polymers, starch must be treated. The surface of modified starch particles is covered by alkyl, which weakens the role of hydrogen bond and improves the compatibility with some resins. At the same time, the blending performance is stronger and tougher than the original starch filling system. The plastics produced by this method have been used in packaging materials, containers and films abroad. China also conducts research in this area, but there is still a gap with foreign countries

1.4 modified starch and protein packaging materials

modified starch and protein packaging materials are mainly used for food packaging and making disposable tableware

1.4.1 modified starch packaging material

starch is a kind of natural polymer material, which is cheap and can be regenerated. After being discarded, it is completely degraded naturally in the natural environment, and can also be eaten or used as feed. The cross-linked product obtained by cross-linking starch with compounds containing hydrophobic groups has water resistance. This material is mainly used to make disposable tableware. The main raw materials are cassava starch, wheat starch and corn starch

1.4.2 raw starch and protein film packaging materials

raw starch and protein film packaging materials are mostly used to make inner packaging bags to package watery food and prevent the spread of flavor in the bags. Protein film and other paper, starch made of composite materials for food packaging. Tableware made of raw starch and paper needs to be coated with a waterproof film because of its poor waterproof performance. Waterproof membrane is usually made of protein, the most commonly used is corn gluten. Corn protein contains 40% gliadin. It is composed of molecules and 25000-40000 proteins. Because the amino acid end of prolamin has non-polar hydrophobic groups such as leucine and alanine, which increases its hydrophobic ability, edible packaging film can be prepared with glycerol and propylene glycol as plasticizers. The film has good oil proof, water-proof and high temperature resistance, so it can be used in the production of disposable tableware

1.5 ultra fine starch packaging material

using modern super powder technology, the raw materials are crushed into 3~1 μ The particles between M are called ultrafine powder. The starch based biodegradable plastic made by this technology has obvious advantages. Superfine starch has small particle size, uniformity and great specific surface area, so the fluidity and filling property are significantly improved. The biodegradable plastic made from it can effectively improve the mechanical properties of the material, and can greatly increase the amount of starch added on the premise of ensuring the performance of the material, which is of great significance for reducing costs, developing the application of natural starch and improving the biodegradation rate of plastic

Wu Jun et al. Prepared ultra-fine starch through the joint treatment of high-speed air mill and ball milling. The study found that when the average particle size of ultra-fine starch was 3.126 μ m. Its crystallinity is reduced from 38.7% to 17.1%. After being plasticized by glycerol, the crystallinity of ultra-fine starch is as low as 9.3%, and its processing performance has been greatly improved. It can be used to prepare food grade biological product packaging film. This ultra-fine starch base film has good mechanical and biodegradable properties. On the premise of ensuring good material properties, the degraded starch has good oil resistance and air permeability, and can be used for general food packaging, It can also be used for the modified atmosphere preservation of packaged fruits and vegetables to prevent the damage caused by a large amount of CO2 due to respiration during the packaging of fresh fruits and vegetables

2 conclusion

the use of starch in the packaging industry has greatly reduced the application of non degradable materials in the packaging industry, alleviated the pressure of the ecological environment to a certain extent, saved resources, and reduced the pollution of the environment to make tensile testing machines, which is of great significance in the packaging industry. But at present, there are still problems in the packaging industry of starch in China, such as the product is not stable and the application range is not wide. There is still a certain gap between the technology of starch in special packaging and that of pressing the "mechanical zero" button in the panel of foreign experimental machines. Therefore, it is particularly important to strengthen the research of starch, especially the research of multifunctional starch packaging materials. Starch has broad development prospects in the packaging industry. (by Zhu Lihong and Fu Heqing)

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