Views:2 Author:Site Editor Publish Time: 2021-04-02 Origin:Site
The pvc pelletizing process is the process of measuring, sticking, plasticizing, and pelletizing high polymer resin with various additives and auxiliaries into pelletized plastics. Plastic pellets are semi-finished products in the plastic molding and processing industry and are also extruded. Injection molding, hollow blow molding, foaming and other molding processing raw materials. So, let's take a look at the principle and process technology of pvc pelletizing extruding machine?
This is the content list:
l What is the technical principle of pvc pelletizing? And what are the advantages?
l What is the formula principle of pvc pelletizing?
l What should be paid attention to in the formulation of pvc pelletizing?
l What are the specific steps of pvc pelletizing?
pvc pelletizing is the most basic and simplest method of pelletizing by extrusion, which is widely used. For various plastic molding processing methods, compared with the direct processing of powder, the advantages of the pellets used in pvc two stage pelletizing extruder are as follows:
(1) Convenient feeding, no need to install a forced feeder in the feeding hopper.
(2) The relative density of granular materials is higher than that of powder materials, and the strength of plastic products is better.
(3) The mixing of resin and various solid powder materials or liquid additives is more uniform, and the physical properties of plastic products are more uniform.
(4) The color of plastic products is uniform.
(5) The granular material contains less air-agent volatile matter, so that the plastic products are not easy to produce bubbles.
(6) The pellets have no pollution to the extruder and production environment.
①According to the use occasion and use requirements of the product;
②According to the prices and sources of raw materials and auxiliary materials;
③ Formulate according to existing equipment and possible conditions.
① pvc pelletizing products are divided into hard, semi-hard and soft. Generally speaking, those with plasticizer content below 10phr are hard PVC products; those with plasticizer content of 10-40phr are semi-hard products; plasticizers Soft products with content above 40phr
② pvc pelletizing is a heat-sensitive plastic, and the PVC formula can contain no plasticizer. For example, rigid pipe, PVC rigid film, PVC twisted film, etc. But there must be no heat stabilizer: in general PVC products, the amount of heat stabilizer is 5-8phr.
③ As mentioned above, in the pvc pelletizing formula, one must have processing aids and toughening agents: in the pvc pelletizing formula without processing aids, hard products cannot be molded, while soft products are difficult to mold.
④In the pvc pelletizing formula, in order to improve the processing ease of plastic products and the gloss of the product surface, lubricants should be added: internal and external lubricants should be appropriately matched, and the dosage should be between 0.5 and 1.5 phr. The surface is damp.
①Two-roll granulation method, the process flow is
pvc pelletizing resin unpacking inspection→screening→weighing formula→high-speed kneading→two-roller car mixing→two-roller car pull→cooling→plate pelletizer cutting.
②The extruder extrudes and cuts pellets, the process flow
pvc pelletizing resin unpacking inspection→screening→formulation→high-speed mixing→cooling mixing→extrusion by extruder→cutting pellets or extruding cooling→cutting pellets.
At present, the purpose of sieving used by pvc pelletizing shrink film manufacturers is to make the particle size of PVC resin powder uniform and easy to operate. If the particles are large, the plasticization temperature will be high, and the time will be longer, and the time required to absorb the plasticizer is longer; if the particles are small, the time required to absorb the plasticizer will be short, the temperature required for plasticization will be low, and the plasticization time will be short; If the distribution is too wide, it is difficult to control the plasticizing temperature and time. Therefore, the PVC resin powder should be sieved before advanced pvc particles pelletizing machine to remove excessive PVC particles.