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做好的塑料袋收缩的原因有哪些?

发布日期:2020-02-27 作者:www.jnsuliao.com 点击:

塑料袋是以塑料为主要原料制成的袋子。它们是人们日常生活中必不可少的物品,经常用来装其他物品。由于其便宜、重量极轻、容量大、易收的优点被广泛使用,所以制成的塑料袋为什么会缩水呢?
Plastic bags are made of plastic as the main raw material. They are indispensable items in people's daily life and are often used to hold other items. Because of its low cost, light weight, large capacity and easy to collect, it is widely used, so why does the plastic bag shrink?
收缩率是塑料袋在成型温度下的尺寸与从模具中取出并冷却到室温的尺寸之差的百分比。它反映了塑料零件从模具中取出并冷却后尺寸的减小。影响塑料收缩率的因素有:塑料品种、成型条件、模具结构等。不同高分子材料的收缩率是不一样的,塑料的收缩率与塑料的形状、内部结构的复杂性、是否有嵌套等。
Shrinkage is the percentage of the difference between the size of the bag at the molding temperature and the size taken out of the mold and cooled to room temperature. It reflects the reduction of the size of the plastic part after it is taken out of the mold and cooled. The factors that affect the shrinkage of plastics are: the variety of plastics, forming conditions, mold structure, etc. The shrinkage rate of different polymer materials is different. The shrinkage rate of plastic is different from the shape of plastic, the complexity of internal structure and nesting.
一、成型工艺对塑料(结构:合成树脂、增塑剂、稳定剂、彩料)收缩率的影响:
1、 Effect of molding process on shrinkage of plastics (structure: synthetic resin, plasticizer, stabilizer, color material):
(1)成型温度保持不变,注塑压力(增大,收缩减小;
(1) The molding temperature remains unchanged, the injection pressure (increases, the shrinkage decreases;
(2)提高维修压力,降低收缩率;
(2) Improve maintenance pressure and reduce shrinkage;
(3)熔体温度升高,收缩率降低;
(3) The shrinkage decreases with the increase of melt temperature;
(4)模具温度高,收缩率增大;
(4) The mold temperature is high, the shrinkage increases;
(5)保压时间长,收缩率降低,但闸门关闭后收缩率不受影响;
(5) The shrinkage decreases with a long holding time, but it is not affected after the gate is closed;
(6)模具冷却时间长,收缩率降低;
(6) The mould has a long cooling time and a low shrinkage;
(7)注射速度快,收缩倾向略有增加,阴影小;
(7) The injection speed was fast, the contraction tendency increased slightly, and the shadow was small;
(8)成型后收缩大,收缩后。塑料袋常用的食品塑料袋是由聚乙烯薄膜制成的,薄膜无毒,所以可以用来装食品。还有一种薄膜是聚氯乙烯制成的,聚氯乙烯本身也是无毒的,但根据薄膜的使用添加的添加剂往往对人体有害,有一定的毒性。所以这种薄膜和薄膜制成的塑料袋不适合装食物。假如要区分聚氯乙烯塑料袋和聚乙烯塑料袋,可以用下面的简单方法进行鉴别。在收缩后的头两天较大,一周左右稳定。
(8) After forming, the shrinkage is large. Plastic bags commonly used in food plastic bags are made of polyethylene film, the film is non-toxic, so it can be used to contain food. Another kind of film is made of PVC. PVC itself is non-toxic, but additives added according to the use of the film are often harmful to human body and have certain toxicity. So the plastic bags made of film and film are not suitable for food. If you want to distinguish PVC plastic bags and polyethylene plastic bags, you can use the following simple method for identification. It was larger in the first two days after contraction and stable in about a week.
济南塑料袋
二世。塑料结构对塑料袋收缩率的影响:
II. Effect of plastic structure on shrinkage of plastic bags:
(1)厚壁塑件收缩率高于薄壁塑件收缩率(但大部分1mm厚壁塑件收缩率高于2mm,因为模具型腔内的熔体阻力增大);
(1) The shrinkage rate of thick wall plastic parts is higher than that of thin wall plastic parts (but the shrinkage rate of most 1mm thick wall plastic parts is higher than 2mm because of the increase of melt resistance in mold cavity);
(2)有镶件的塑料件的收缩率比无镶件小;
(2) The shrinkage of plastic parts with inserts is smaller than that without inserts;
(3)形状复杂的塑料件收缩率小于形状简单的塑料件收缩率;
(3) The shrinkage of complex plastic parts is smaller than that of simple plastic parts;
(4)塑件高度方向的收缩率一般小于水平方向的收缩率;
(4) The shrinkage in the height direction of the plastic part is generally smaller than that in the horizontal direction;
(5)细长塑性件在长度方向上的收缩率较小;
(5) The shrinkage of slender plastic parts is smaller in the length direction;
(6)长度尺寸的收缩率小于厚度尺寸的收缩率;
(6) The shrinkage of length dimension is smaller than that of thickness dimension;
(7)内孔收缩率大,外孔收缩率小。塑料袋是人们日常生活中必不可少的一部分,经常被用来装其他东西。它具有成本低、重量轻、容量大、储存方便等优点,得到了广泛的应用。然而,由于它的缺点是降解周期极长和难以处理,一些国家已经禁止生产和使用塑料袋。
(7) The shrinkage rate of inner hole is large and that of outer hole is small. Plastic bags are an indispensable part of people's daily life, often used to hold other things. It has the advantages of low cost, light weight, large capacity and convenient storage, and has been widely used. However, some countries have banned the production and use of plastic bags due to its long degradation cycle and difficult to handle.


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