The action of the blown film mold is to eat the melt sent by the extruder, and shaft the melt, so that the melt is flowed longitudinally, and the mold exit is sent out to facilitate the final product. High quality melt transport is not only the requirements of the extruder, but also the requirements for the mold. That is, the melt flow is not in the inside of the mold, and there is no need to occur in the occurrence of the mount. Further, high melt quality also requires no appearance or structural problems such as the flow path line fusion line. Finally, good molds also require a uniform extrusion speed on the circumference.     The blown film mold has several different structures, which are different in cost, complexity and design purposes. The mold, the mold, the bottom feeding, and the spiral core is often used in the extrusion of the single layer film. Co-extrusion molds are used to produce multilayer coextruded films. Wire rotating molds can be used regardless of a single layer film or a multilayer film. These contents will be described in the next chapter.     Side feeding molds (Figure 3.4) are

    Carbon elements can also be used as an additive for extruding machines, with two main forms: carbon black and carbon fibers. Both have hygroscopicity, need to dry in advance or use extrusion equipment with the function. Carbon black is generally powdered, often used in outdoor, can absorb ultraviolet rays. Adding carbon black can extend the life of high molecular products.     Carbon black is also a very large amount of colorant, which is relatively inexpensive, and can improve the conductivity of the product. The use of carbon black is difficult to process, and it is easy to pollute the environment. So the use of carbon black is usually in the form of color mother, although this cost is high. Products to carbon fibers can effectively improve a variety of properties. Although the cost is relatively high, the carbon fiber is very tough, which can improve the mechanical properties of the product very effectively. The carbon fiber is usually a relatively short fragment of a relatively short fragment when crowded with a polymer. Due to conductivity, carbon fibers can effectively eliminate product surface static electricity.     Clay as an additive application is increasingly wide. When co-extruded with

1.2.4 colorant     The colorant can be said to be the most widely used additive in the plastic industry. Colorants give plastic colorful appearance. The main purpose of coloring is of course color, or other effects, such as carbon black, can absorb ultraviolet rays. There are several ways to coloration. 4 of which are widely used, such as raw materials are mixed into colorants, colors, dry color, wet coloring. The mixing method is mixed into the pigment in the raw material.     This method is the earliest use of a raw material carrier or other equipment, mainly used in a single screw extruded a single raw material. The color of the color can be done very well.This method is slightly higher than the new coloring method.     The color master method is a method of mixing the pigment in a polymer feedstock to make a re-participation in extrusion. The color-containing pigment is high, and this method can control the color concentration in high precision. Usually add 4% color mother can be well colored, compared to the mixing method for modification. If the mixing is carried out primarily in the extruder, this method is most efficient. The dry

1.2.1 anti-adhesive     The action of anti-adhesive is to prevent high molecular materials from sticking sticky. The blown film process is more likely to generate surface adhesion compared to other processes because the membrane bubbles are pressed against the first traction roller. The anti-adhesive can separate the two films. Celite is a common anti-adhesive material. 1.2.2 antioxidant Antioxidants can inhibit molecular decomposition of the polymer. The polymer chain is easily broken into a segment in an aerobic environment, especially when high temperature extrusion is extruded. Degraded polymers usually discolor and reduce product mechanical properties. Crosslinking (gel) will also be generated during oxidation. Many raw materials themselves contain antioxidants even without adding antioxidants. This ensures thermal stability in polymer processing. The action mechanism of antioxidants is to capture it before the free radical complex polymer segment produced by the oxidation reaction. Antioxidants are mainly divided into two types of phenolic and amines. 1.2.3 antistatic agent Anti-static agents are used to eliminate the electrostatic surface of the polymer. Many high molecules will accumulate electrons during processing, including the process of guiding the film through the guide roller. This phenomenon is particularly obvious when humidity is low. The mechanism of antistatic agents

2.1.6.1 Temperature Control     The current temperature control technology can control the temperature fluctuation of each heating zone within ± 1 ° C. Such levels are acceptable in practice. However, temperature fluctuations exceeds a certain range, affecting yield fluctuations. Therefore, strict temperature control is very necessary. A set of extruder systems typically have several temperature control zones. The temperature control area depends on the length of the cartridge, the shape and length of the adapter and the size and shape of the mold. There are three temperature control zones, and there are more than a dozen. The temperature control area consists of the following four parts: Temperature controller, temperature sensor, heater, cooling unit. Usually only the cartridge heating zone requires a cooling unit. The temperature controller is a microprocessor. Its main function is to read the actual temperature of the part of the thermocouple output, compare it with the set temperature, and then issue a control signal command heater or cooling unit operation. The temperature controller can control the heater to open or close, control the cooling unit switch, or not actions. This action loop is constantly repeating to ensure that the actual temperature is consistent with the set

    The cooling mode of the plastic recovery granules, the particulate device and the head are different, and the process flow and yield of granulation are different. How do customers choose to fit their granulation mode when purchasing a plastic granulator?     Shanghai Duxia Industry and Trade Co., Ltd. will analyze the characteristics of each pelletizing under way, increase the understanding of the plastic granulator.     1. First of all, we will introduce you the simplest particulate mode in granulation, low yield, and the method is — Water-cooled strand pelletizing.     Strand pelletizing mainly for laboratory and production of small manufacturers, the process is as follows:     Single screw / twin screw extruder → filter plate and mesh → pull head → air cooling or water cooling → rotary knife particles → cylindrical particles. The pull strips belly belongs to the cold cutting method, and most of the plastic particles can be used in this method, such as the dyeing or small amount suitable for various plastics such as PET, PVC, PE, PP, PA, ABS, PS, HIPS. Mixed extrusion granulation of modifier and filler. This mode has a large area and is inconvenient. https://youtu.be/G7yTnwGPvjc 2.

2.1.4 Map Screw     The barrel screw (Figure 2.6) is called the heart of the extrusion system. Its key role is more than melting material, and the material is uniformly plasticized, and uniformly stable temperature and pressure is established. Temperature and pressure instability ultimately lead to size deviations and quality problems of the product. 2.1.4.1 screw     The screw (Figure 2.7) is a long axis with a screw. The screw is a screw guide. There are many kinds of screw design patterns, mainly divided into three segments: feeding segments, melting segments, metrics. The screw depth is an important parameter of the screw compression function, which is typically deepened at the feeding section and is deeply distributed axially, and the measuring segment is minimized and the axial direction is deeply distributed, and the melting section is deep to a light gradation.   The compression of the screw is measured by the compression ratio: Compression ratio = feed section screw depth / meter (delivery section) screw groove depth Typical compression ratio between 2: 1 to 4: 1, mainly depending on the type of raw material and its loose density. Another important indicator of the screw is a long diameter ratio

Description of the extruder     The extruder is the core of the entire blown film extrusion system, which is heated and knead on the raw material to obtain a uniform plasticized melt for a mold shape. Although this book mainly explains the hardware and blown film processes, this chapter is also described in the extruder structure and its principles. Product quality and productivity depends on the extruder, which is undoubtedly critical. This chapter mainly includes two parts: extruder hardware and extrusion principle. The first part will introduce the main components of the extruder, and talk about its functions and specific dimensions. The second part will introduce how the extruders interact, how to process raw materials. In other words, what is the extrusion process will be described in the extrusion process. This part of the narrative is relatively simple, just a spread of the basic knowledge of the film drying process. Extruder hardware system     The effect of the extruder is a melt that is uniformly plasticized by constant temperature constant pressure to form a die. This definition clarifies the three effects that the extruder must be achieved during the process of processing materials. First, the melt is homogenized,

1. Definition and classification of biodegradable plasticsBiodegradable plastics are a type of polymer materials that are degraded through the action of microorganisms that exist in nature, such as molds (fungi), bacteria and algae. Biodegradable plastics not only have excellent degradation properties and can adjust their chemical structure to achieve controllable degradation, and biodegradable plastics have good biocompatibility, thermal stability and mechanical properties, and they also have relatively stable chemical properties. Easy to store and use and other advantages.According to the method of synthesis and the source of raw materials, biodegradable plastics can be divided into bio-based degradable plastics and petroleum-based degradable plastics.Commercially available bio-based degradable plastics include: polylactic acid (PLA), regenerated cellulose, starch plastics, polyhydroxy fatty acid ester polymers (PHAs), etc. PHAs biodegradable plastics include poly-3-hydroxybutyrate (PHB), copolymers of 3-hydroxybutyrate and 3-hydroxyvalerate (PHBV), and 3-hydroxybutyrate and 3-hydroxyhexyl Copolymer of acid ester (PHBH).Commercialized petroleum-based biodegradable plastics include: polybutylene succinate (PBS), polycaprolactone (PCL), polyglycolic acid (PGA), carbon dioxide degradable plastics (generally refers to carbon dioxide and epoxy Propyl ring polymer (PPC), and a class of copolyesters. Common degradable materials   Name  Synthesis  Advantage Disadvantage Use  Polyhydroxyalkanoate (PHA) Microbial synthetic intracellular polyester Biodegradability. Biocompatibility High knot degree, brittleness, poor thermal stability Drug release,

    In order to obtain satisfactory film quality for blown film, in addition to have a suitable blown film machine, a suitable formula is also required.    The main effects that the blown film formula needs to achieve are: good tensile strength, good film stretch rate, good film tearing strength, and strong hand feeling. These are the four main functions that the blown film formula must achieve.    The key skills of the formula: 1. Understand the resin density 2. Understand the resin melt index 3. Understand the density of the comprehensive formula, so that you can know the performance of the formula.    The basic principle of ingredients: as far as possible to reduce costs while meeting customer needs. There are several main points to reduce costs, namely: 1. Add filler to increase weight, 2. Add recycled materials to replace new materials. But pay attention to the four prerequisites, otherwise the customer will run away, and the gain will not be worth the loss!     Shanghai Duxia Industry and Trade Co., Ltd. now introduces some common blown film formulas and explains them for free, hoping to help our downstream customers. LDPE new material LLDPE LDPE recycled material