Information and Information Plant Fiber Foaming Materials Research Background, Current Status and Process Discussion Zhou Shenghua (Hangzhou University of Electronic Science and Technology, Hangzhou 310018) focuses on the development of foaming technology that has no impact on the environment. There are two main methods for making products: one-step molding and two-step molding. The production, process and selection of foaming agents and the development status at home and abroad were introduced.
In today's world, in the process of resolving the contradiction between packaging and the environment and vigorously developing green packaging, the main focus is on the development of green packaging materials.
Green packaging materials are materials that have the lowest environmental burden and the highest recycling efficiency throughout the life cycle. Green packaging materials are the core of green packaging. It not only reduces and eliminates environmental pollution, relieves pressure on the ecological environment, but also saves resources, replaces some lacking or valuable resources, and recycles used resources. The countries of the world attach great importance to it and have invested a lot of money and manpower for development. At present, many important achievements have been made.
In the field of cushion packaging, the earliest cushioning materials used are corrugated paper liners, separators, and waste paper strips. The need for a large amount of manual labor cushioning during the packing process is not ideal for EPS foam plastics. EPS foam plastic products are one of the main products polluting the environment and face the trend of elimination. However, EPS foam products as the packaging material - the first choice for shock lining, its superior packaging performance and low price, has not yet found an ideal substitute.
At present, the main substitute product is pulp molded shockproof lining packaging products, which are made of plant fibers such as waste newspapers and carton paper, which are formed by hydro-mechanical pulping, vacuum forming of molds, and drying. Its product applications can cover electronics, mechanical parts, industrial instrumentation, electrical tools, home appliances, computers, glass, ceramics and foam products, agricultural products and other industries. However, because its products are too dense, the seismic and impact resistance is much lower than that of EPS materials. The seismic and impact resistance of the products is mainly ensured by the geometric structure of the products. Due to the influence of the structure and processing of the molds, the development of the products is greatly affected. The restriction can only produce small packaging liners, and the packaging liners and fillings for making large household appliances still use EPS foamed plastic products. This technical problem has not been effectively solved so far. At the same time, since the cost of pulp molding is higher than the cost of EPS foam products, the development of pulp molded articles is also greatly limited.
In recent years, a new type of packaging product material, a plant fiber foam packaging product and its molding technology, are being researched and developed, which is based on plant fiber (waste newspaper, carton paper and other plant fiber materials, etc.) and starch supplementation. Made of agent material, the new packaging product material has the advantages of no pollution to the environment, simple production process, low cost, wide source of raw materials, shockproof and shockproof performance superior to pulp molded products, etc., not only can make shockproof lining, but also can replace EPS produces a filled particle object, and its effect is basically equivalent to that of an EPS product.
122 Influencing factors The factors of the foaming agent itself, including the type, concentration, activation mode, solubility, etc., external factors include foaming time, melt temperature, pressure, melt viscosity, added additives and the like. Foaming is often controlled in the processing process by controlling the content, time, temperature, and pressure of the blowing agent. The effects of temperature and pressure on the cells are discussed below.
As the melt temperature increases, the surface tension of the polymer melt and the solubility of the gas in the polymer melt decrease, while the diffusion coefficient of the gas in the polymer melt increases. The reduction of the surface tension of the polymer melt reduces the critical free energy barrier of bubble nucleation and promotes bubble nucleation; the smaller the solubility of the gas in the polymer, the greater the supersaturation of the gas, and the more favorable the formation of the bubble core; The larger the diffusion coefficient of the gas in the polymer melt, the smaller the kinetic resistance of the bubble nucleation, and the easier it is to nucleate.
In summary, increasing the polymer melt temperature can promote the formation of bubble nuclei.
When the pressure outside the mold increases, the amount of gas discharged from the mold decreases, the actual pressure of the gas in the mold increases, the solubility of the gas in the polymer increases, and the diffusion rate increases, so the amount of gas diffused into the polymer increases, and after the pressure reduction, the gas The supersaturation in the polymer is large, and the nucleation driving force is large. Under the same conditions, the density of the nucleation is large, the distance between the nucleus is small, and the amount of gas that provides a single bubble growth is reduced, and the cell diameter is changed. small.
Brief introduction and comparison of 123 commonly used foaming agents The foaming agents currently used for plant fiber foaming materials mainly include: sodium hydrogencarbonate (NHX3), urea, 4 4 oxobisbenzenesulfonyl hydrazide (B; H), Nitroformamide (AC) tosylhydrazide and the like.
The decomposition gas and residue are non-toxic and odorless, and do not pollute the environment; the decomposition gas is mainly N, cqnh3, co2; high gas generation, no foaming in advance; uniform and dense cells, low price; wide range of activators selected; decomposition temperature High, the decomposition speed is too fast; the thermal decomposition range is narrow, the decomposition is sudden and strong, and foaming is easy.
Modification of AC foaming agent: The modification of AC product is to optimize the gas generation amount, particle size, color and thermal decomposition temperature of the foaming agent.
In the preparation process, certain reaction conditions are changed or certain additives are added; additives are added to the AC raw powder; different types of foaming agents are compounded to achieve the modification effect. The main modification method is to add some accelerators.
Particle refinement. It mainly pulverizes and classifies the original powder of the foaming agent.
Low temperature type. Mainly one or more activators are selected in combination with AC in a certain ratio.
Highly dispersible type. The AC foaming agent may be mixed with a fine powder of some inert inorganic compound, and a surfactant or the like may be added to the AC product.
Compound. Other auxiliaries with specific functions can be mixed with AC, or several kinds of foaming agents can be mixed with each other, and compounded into one body according to the principle of synergy between various auxiliaries.
A colorless, odorless, non-toxic, non-colored, high-efficiency nitrogen-based foaming agent. It can be rapidly decomposed in a very narrow temperature range and in a short period of time; it produces a large amount of non-toxic and odorless nitrogen and water vapor; low-temperature foaming agent, moderate heat in foaming process; pore structure is fine and uniform, no coloring, decomposition The residue does not pollute the product; it is widely used and is known as a universal foaming agent. However, the dispersion is poor, the amount of gas generated is small, and the price is expensive.
13 Research Status of Plant Fiber Foam Products in China Most of the current researches in China are the production process of plant fiber foam products using foaming agents. The following is a new composite cushioning packaging material with corn stalk fiber as reinforcement, taking the following specific manufacturing process.
Corn stalks are used as raw materials, and the fibers are disintegrated by pulverization, surface treatment and smelting, and foamed materials are prepared by compounding with polyurethane. On the one hand, it can compensate for the defects of cushioning properties of paper cushioning materials; on the other hand, it can enhance the foam plastics. Degradation performance; In addition, the effects of process parameters such as the amount of corn stalk fiber, the amount of foaming agent, the amount of cross-linking agent and catalyst, and reaction temperature on the buffer properties of the material were investigated.
The main raw materials of 131 materials and reagent buffer packaging materials are shown in Table 1. Table 1 Main raw materials of corn straw fiber composite buffer packaging materials Name of main role Remarks Plant straw fiber reinforcement 90 mesh crushing diethylene glycol polyglycol, ethylene glycol Matrix main reaction raw material water foaming agent dibutyltin dilaurate cross-linking agent to improve the mechanical properties of the bubble Triethylene diamine catalyst catalytic foaming and gel reaction dimethyl octoxane foam stabilizer to stabilize the bubble and control the bubble The size and structure of the hole is similar to the method of 132 and the temperature and humidity of the sample are processed until the sample quality is balanced. Take a certain amount of fiber, dissolve 1mm under the condition of 3% concentration of pulp, add the adhesive, foaming agent and filler under the condition of stirring, stir evenly, pour into the homemade molding mold, put into the electric heating and blast The drying oven was dried at 120 ° C for 6 hours to obtain a foam.
The performance of the 133 foam was measured by gradually increasing the load on the experimental sample in the thickness direction at a speed of (12 ± 3) mm/mn, and recording the compressive force and the corresponding deformation during the compression. After the static compression test, a pressure-deformation curve of the material is obtained. To eliminate the effect of material size, convert it to a stress-strain curve.
The degree m is compared with the stress-strain curve of the EPS (polystyrene) buffer material. The experimental results show that the performance of the buffer material is close to that of polystyrene, but the elastic failure rate of the material is higher than that of the poly. Styrene is fast.
2 Foreign developments Developed countries such as Europe, the United States and Japan are also pursuing research on plant fiber foaming technology in search of new environmentally friendly packaging materials without pollution. It is expected that this new packaging material can replace the EPS foaming materials that are still widely used. . The process method adopted by foreign plant fiber foam products mainly concentrates on not adding chemical foaming agent, that is, foaming agent is not required to be foamed, and the raw material is foamed by the action of water vapor to form a granular foaming pulp. The process of the product is more difficult than the process of adding a chemical foaming agent, but the production and use of the plant fiber foamed product does not adversely affect the environment.
At present, developed countries have achieved remarkable results in this technology: Germany Bremen PSP uses old books, waste newspapers and flour as raw materials to develop foam paper production process, and its production process is first recycled. The old book newspaper is cut into shreds, and then ground into fibrous pulp, which is mixed with flour in a ratio of 2:1. The mixed pulp is injected into an extruder to be pressed into cylindrical particles; during the extrusion process, the raw materials are subjected to water vapor. Foaming, forming foamed paper, using foamed paper granules as raw materials, can produce different shapes of packaging materials according to needs. Compared with foamed plastics, the production process of foamed paper is relatively simple, and can be molded at one time, eliminating multiple times. Bubble and cooling process. The foaming of the foamed paper does not require chemical additives, only water vapor, which can be treated like ordinary garbage, and the used foam paper can be recycled and reprocessed, and its production and use have no influence on the environment.
From the perspective of economic efficiency, foam paper is 10% cheaper than foam when it produces the same amount of packaging materials. This foam paper has great application prospects. It can be used not only as packaging materials, but also as insulating materials and building materials. .
Sakamoto Teijin has developed a new environmentally-friendly foaming material that uses pulp as a raw material. The foamed material is processed into granular or strips using natural pulp as a raw material. It is easily molded into various shapes after heating. It is lighter and expands like the traditional foaming material. It has the same impact absorption properties and can be used as an ideal packaging material. At present, the biggest shortcoming of this material is the high cost. The company is not yet mass-produced and is trying to reduce costs.
Sakamoto Industrial Technology Research Institute developed a dry pulp foaming technology using waste paper as a raw material, which does not need to be dissolved in water. Compared with the previous wet pulp molding method, the technology for producing packaging materials has better biodegradability and does not cause secondary pollution. The technology is to pulverize waste paper to less than 5mm2, mix with starch paste to make particles with a diameter of 1~3mm, blow the particles into the metal mold in the open state, and then close the metal mold for pressure heating, in the paste. The contained moisture is discharged from the vent hole during the heating process, and a packaged product having a precision and a wall thickness corresponding to the metal mold can be produced. In the production of the foamed packaging material, the small particles of the waste paper and the starch paste may be previously foamed, the foam is coated with a starch paste and blown into the metal mold, or the small particles are added to the foaming material in the metal mold. Foaming. Since this technology does not require a large amount of water, there is no need for a wet pulp line product to require a drying line and a wastewater treatment equipment. 3 The overall trend of plant fiber foaming has the following three points: the key development has no impact on the environment. Plant fiber foaming technology.
That is to vigorously develop and research the use of water vapor technology to achieve the foaming of plant fibers to completely avoid adverse effects on the environment.
Strengthen the development of production technology and equipment for plant fiber foam products.
At present, research on plant fiber foam packaging products is still in the experimental stage, both domestically and abroad, and has not yet reached the requirements for industrialized large-scale continuous production. In order to achieve this goal, research should be strengthened in terms of product formulation, selection of process parameters, research on special equipment, design of special molds, etc., especially in meeting the requirements for continuous and automated production. Breakthrough.
The characteristics of plant fiber foam packaging products should be comprehensively and systematically studied.
At present, the research on the performance characteristics of plant fiber foam packaging products mainly focuses on single piece and experimental, but the performance parameters of multiple pieces or practical applications have not been verified, so the research intensity should be increased in this respect. The performance parameters of plant fiber blister packaging products under various practical conditions, in order to carry out targeted improvement and improve the comprehensive performance of plant fiber blister packaging products.
(Finish)
Oil Cooler for Excavator PC200 PC210 PC220 PC270 PC300 PC350 PC400 PC450 EC160 EC210 EC240 EC290 EC330 EC360 EC460 and other models.
Our Advantage:
1. Excavator spare parts in full-scale are available;
2. 100% quality assurance, develop and manufacture follow original ones;
3. Quick response within 24 hours ;
4. Small order allowed;
5. Reasonable stock and timely delivery;
6. Original packing, neutral packing or customized packing;
7. Excellent After-sales service.
Oil Cooler
Oil Cooler,After Cooler,Engine Oil Cooler,Hydraulic Oil Cooler
Jining Tongderui Construction Machinery Co., Ltd. , https://www.tdr-excavatorparts.com