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1 Introduction With the wide use of "" plastic woven bags (hereinafter referred to as "bags"), the production of "" bags is getting larger and larger. With this, there are more and more waste bags. The recycling of these waste bags is an effective measure to reduce production costs, protect the environment, and make full use of resources. In recent years, many manufacturers have conducted research in this area.
What is discussed here is the ""recycling of the bag, waste" means the "plastic waste" suitable for the production of "bags." This is a single species of waste, which requires a relatively high demand, cannot be mixed with other varieties of plastics, and can not contain sediment, impurities, mechanical impurities, etc., and its melt index requirement is in the range of 2--5 (not any PP plastics are available). There are two main sources of it, one is the "" waste in the bag production process; the second is the waste pp bag of recycled products, such as fertilizer bags, feed bags, salt bags and so on.
2 Regeneration method It mainly consists of melt granulation method and extrusion granulation method, and most of them adopt extrusion granulation method. The flow of the two methods is as follows.
2.1 The method of melted pellets - selected materials and washed - dry - cutting - high-speed pellets (feed - heat shrink - spray - pellets) out of the packaging.
2.2 Extrusion granulation waste - selection of materials - washing - drying - cutting - heat extrusion - cooling granulation - packaging.
The equipment used in the extrusion method is a self-made two-stage extruder, and a vented extruder can also be used to exclude the gas generated during the extrusion of the waste. To eliminate impurities in the waste, an 80-120 mesh screen must be used at the discharge end of the extruder. The regenerated extrusion process conditions are shown in Table 1.
The temperature of the extruder must be controlled properly, not too high or too low. If the temperature is too high, it may cause yellowing and blackening of the material, which may seriously affect the strength and appearance of the plastic. If the temperature is too low, the plasticization is poor, the extrusion rate is low, and even the material is not discharged, and the filter is particularly likely to be damaged. The appropriate regeneration extrusion temperature should be specifically determined based on the results of sampling the melt index of each batch of recovered waste. The temperature conditions in Table 1 are based on the general rules of production practice.
3. The use of recycled materials and the impact on the performance of pp bags Due to the thermal aging of the plastic processing has a considerable impact on the performance, especially the recovery of the "" bag after two or even many thermal processes, plus prior to recycling in use UV aging, performance has significantly decreased. Table # test data can illustrate this.
It can be seen that the recycling of ""bags cannot be used indefinitely. If it is used alone to produce recycled pp bags, it can only be regenerated three times. Since it is difficult to judge how many times it was recycled, it is necessary to ensure the quality of pp bags.
Even the less demanding bags should be mixed with new materials and recycled materials in production. The proportion of the mixture should be determined based on the measured data of the two materials. The amount of recycled material directly affects the quality of the pp bag flat yarn. The table is a set of comparative data in production practice.
The quality of the woven bag is the key to the relative tensile strength and elongation of the flat yarn. The strength of the flat yarn specified by the national standard (gb8946--88) is >=0.03 N/d, and the elongation is 15%--30. .% Therefore, in production, 40% of recycled material is generally added. Depending on the quality of the regrind, 50% - 60% can sometimes be added. The more the amount of regenerated material added, the lower the production cost, the less the quality of the bag. Therefore, the amount of recycled material can only be added properly under the premise of ensuring the quality.
4. The use of recycled materials for the adjustment of the drawing process due to heat aging caused by the repeated thermal processing of pp plastics and ultraviolet radiation aging in long-term use, resulting in the increase of the melt index of pp regrind with the increasing number of processing times (see Table 2). . Therefore, after a large amount of recycled material is added to the new material, relative to the new material, the temperature of the extruder, the temperature of the head, and the temperature of the stretching and forming should all be adjusted down properly. The amount of adjustment should pass the test. The melt index of the mix is ​​determined.
On the other hand, since the recycled material is processed many times, the molecular weight is reduced, a large number of short molecular chains exist, and after multiple stretching orientations. Therefore, in the production process, the draw ratio is also lower than the same brand new material. Generally, the new material has a stretching ratio of 4- to 5-fold, and generally 4 to 4 times after adding 40% of the recycled material. Also due to the increase of the melt index of the recycled material, the viscosity is reduced and the extrusion rate is increased. Therefore, under the same screw speed and temperature conditions, the drawing speed of the wire drawing is also slightly faster. In the mixing of old and new raw materials, it is worth noting that they should be mixed evenly; at the same time, they should try their best to match raw materials with similar melt index. Melt index difference, a large difference in melting temperature. In plasticizing and extruding, two kinds of raw materials cannot be plasticized at the same time, which will seriously affect the extrusion and drawing speed, resulting in high reject rate and even failure to produce.
5. Conclusions As mentioned above, the recycling and reuse of pp bags is entirely feasible as long as careful selection of materials, proper process recipes, and reasonable and accurate process conditions are controlled. Does not affect the quality of the product, but the economic benefits are obvious. The unit cost of woven bags produced after adding 40% recycled material can be reduced by about 20%.
The decorative textile industry is generally known as home textiles, that is, home textiles, and the bedding industry is one of the sub-sectors of home textiles. Bedding is an important part of home textiles, according to the classification of China Home Textiles Association: including 1. Bedding, 2. Curtains, 3. Washing and kitchen textiles, 4. Furniture textiles (cushions, seat cushions), etc. In China, the bedding industry is also called bedding industry, or bedding industry, bedding industry and interior soft decoration industry. The concept of overall bedding is to integrate various bedding pieces for integrated design and sell them in combination.
Classification
1. Covers: including Quilt covers, bedspreads and sheets.
2. Pillow categories: initially can be divided into pillowcases, pillow cores, pillowcases are further divided into short pillowcases, long pillowcases, square pillowcases, etc., pillow cores are further divided into four-hole fiber pillows, square pillows, kapok pillows, magnetic pillows, latex pillows , chrysanthemum pillow, buckwheat pillow, cassia pillow, etc.
3. Bedding: seven-hole quilt, four-hole quilt, air-conditioning quilt, protective pad;
4. Kits: four-piece, five-piece, six-piece, seven-piece.
Bed Set,Bed Sheet,Duvet Cover,Bed Cover,Bed Sheet Set
Shaanxi Xiaoze Textile Co., Ltd. , https://www.xtsxxzth.com