Among the various types of plastic film, polyethylene film is one of the most diverse and most extensive types of film types. In order to facilitate readers to better choose the type of resin raw materials in production applications and formulation design, we are The grades and applications of vinyl resins are partially summarized and summarized for customers’ reference. Usually what we call polyethylene is actually a general term for a large class of ethylene homopolymer and copolymer. According to the difference of molecular structure and density, polyethylene is roughly divided into three types: low density polyethylene, high density polyethylene and linear low density polyethylene. Although ethylene plastomers and elastomers are also in the large polyethylene category, because their properties are far from common polyethylene resins, most of the time they will be discussed separately. Even the three most common types of polyethylene have different characteristics. Let’s sort it out carefully for everyone below. Low density polyethylene (LDPE) Low-density polyethylene, abbreviated as LDPE, is the earliest commercially produced polyethylene variety. In the 1930s, it was first commercialized by ICI. Low-density polyethylene is a homopolymer synthesized by free radical polymerization of ethylene monomer under extremely high pressure. Due to the high
Polyethylene film (PE film) is widely used in heat-sealing layer, surface layer, etc. in the field of flexible packaging due to its excellent performance. Moreover, due to the strengthening of corporate brand awareness and the further demand of consumers for beautiful packaging, different colors are used on flexible packaging. And the printing of patterns has also become a research topic in the field of flexible film packaging. Common flexible film packaging forms mainly include flexo printing and gravure printing. At present, there are more flexographic printing on the market, but the high investment in flexographic printing equipment makes gravure printing gradually applied to the printing of PE film. At present, when PE film is printed with gravure, it is easy to produce poor printing adaptation problems such as poor chromatic quality and poor inking. The film thickness uniformity, film physical properties, film surface wetting tension, Coefficient of friction. Below we will share with readers by analyzing the impact of the physical properties of polyethylene film on printing. Film thickness uniformity In gravure printing, if the polyethylene film has poor thickness uniformity, first of all, the problem of inaccurate color registration will occur. Even after the color
The long Spring Festival holiday is approaching, and film production companies need to carry out necessary maintenance and maintenance of production equipment in advance. Following the introduction of the maintenance knowledge of the blown film unit in the last issue, we will introduce the maintenance of the cast film unit. Multilayer co-extrusion cast film extrusion technology is a traditional film extrusion production process. The biggest advantage of this process is that it has extremely high processing accuracy and can maximize the performance of the processed material. Therefore, for the casting device, the following parts need to be inspected and maintained before shutting down and before starting up. Such as: Regularly clean the casting roll, air knife, and vacuum device; Keep the surface of the roller clean and clear of impurities and oil on the roller; Regularly check the tension of the drive belt and chain once to ensure proper tension; Regularly check the cooling device to ensure that the readings of all meters are accurate and work normally; Regularly inspect and clean the lubricating transmission device once to ensure normal operation. In addition to the above
As the Spring Festival is approaching, most of China’s production companies have started to suspend production for a longer period of time. Before the holiday, necessary maintenance and maintenance of production equipment is a guarantee for smooth reproduction in the second year. As a film blowing machine, because of the characteristics of its product process, the plastic film blowing machine basically runs 24 hours a day. The film blowing equipment operating at full load has a large loss of the machine body. If the film blowing machine is not maintained and maintained in time, it will have an impact on the service life of the film blowing machine, the precision and quality of the film products. So, as a film blowing machine operating captain, how to do maintenance and maintenance work? 1. Electrical maintenance: Ensure the stability and reliability of the power supply, and the performance parameters meet the requirements; Maintain proper temperature and humidity, maintain a good grounding, and pay attention to eliminating the danger of static electricity; Clean the radiator dust regularly; Note: In the maintenance of electrical appliances, it is forbidden to repair core components with power.
In our daily life, indispensable food and medicine are always accompanied by various plastic films. What materials are these films made of? What are the performance characteristics of each? Below, Shanghai Duxia Industry and Trade Co., Ltd. will briefly introduce some of the most common plastic film packaging materials. Biaxially oriented polypropylene film (BOPP) The biaxially oriented polypropylene film is obtained by co-extruding polypropylene particles to form a sheet, and then stretching in both vertical and horizontal directions. Due to the orientation of the stretched molecules, the film has good physical stability, mechanical strength, air tightness, high transparency and gloss, toughness and wear resistance, and is currently the most widely used printing film. Generally, the thickness is 20-40μm, and the most widely used is 20μm. Its main disadvantage is poor heat-sealability, so it is generally used as the outer layer of composite film. For example, it has ideal moisture resistance, transparency, strength, stiffness and printability after being composited with polyethylene film. It is suitable for holding dry food. Since the surface of the biaxially oriented polypropylene film is non-polar, the crystallinity is high, and the surface free energy is low, its printing performance
Upstream production of degradable plastics The upstream raw materials of degradable plastics mainly include PLA (polylactic acid), PHA (polyhydroxyalkanoate), PGA, PBS (polybutylene succinate), PBAT (polybutylene adipate/terephthalate) ), PCL (polycaprolactone), etc. Degradable plastic midstream products mainly include tableware, plastic film, film paper, express bags, clothing, plastic tape, 3D printing materials, etc. The downstream degradable plastics are mainly used in packaging, agriculture, 3D printing, modern medicine, textile industry, etc. PLA (polylactic acid) PLA: It is one of the most common degradable plastics. It is a polymer polymerized with lactic acid as the main raw material. The PLA production process is pollution-free, and the product can be biodegradable. After use, PLA can be composted and degraded into carbon dioxide and water at a temperature higher than 55C or enriched with oxygen and microorganisms, so as to realize the material circulation in the natural world without affecting the environment. Make an impact. PLA also has reliable biological safety, biodegradability, good mechanical properties and easy processing. It is widely used in packaging, textile industry, agricultural film and biomedical polymers and other industries. The degradable plastic raw material is polylactic acid. As companies are optimistic about the replacement demand under
A must-see for blown film: super detailed heat shrinkable film formulation design and formulation examples, very practical!
A must-see for blown film: super detailed heat shrinkable film formulation design and formulation examples, very practical! Heat shrinkable film (Shrink film for short) is blow molded by rapid cooling and shaping. This rapid cooling production process is designed according to the principle of polymer orientation. When the resin is completely plasticized and extruded into embryo film, polymerization The material is forced to stretch in the vertical and horizontal directions between the glass transition temperature and the viscous flow temperature, so that the molecular chains of the polymer are oriented along the stretching direction. At this time, the film is rapidly cooled to “freeze” the strain generated by the stretching orientation. . When the film is reheated to the “thawing” temperature, stress relaxation will occur, that is, the oriented molecular chain will de-orientate. At this time, the stretched chain that is forced to be in a state of tension will return to the folded state before the orientation. Chain, thus giving the shrink film good shrink properties. Especially in the packaging industry, shrink film is replacing other packaging materials due to its high quality and low price. Resin for shrink film As
Plastic Introduction Using monomers as raw materials, polymer compounds formed by polyaddition or polycondensation reactions are called “synthetic resins” (resin), sometimes simply referred to as “resin”. Based on synthetic resin, it is a material that can be plasticized by adding some additives according to the application requirements. We call it “plastic” (plastic). Common additives in plastics include: stabilizers, antioxidants, plasticizers, fillers, lubricants or color concentrates, etc. These additives can be used alone or in combination. Resin The main component of plastic is resin. The term resin was originally named for lipids secreted by animals and plants, such as rosin, shellac, etc. Resin refers to a polymer compound that has not been mixed with various additives. The resin accounts for about 40% to 100% of the total weight of the plastic. The basic properties of plastics are mainly determined by the nature of the resin, but additives also play an important role. Some plastics are basically composed of synthetic resins, with no or little additives, such as plexiglass and polystyrene. Plastics can be divided into thermoplastics and thermosetting plastics according to their behavior when heated; they can be divided
Working principle of EPC The EPC device is installed at the TDO entrance of the film production line to accurately track the position of the film edge. Its working principle can be simplified as a closed-loop control loop: the starting point of automatic correction is the current position of the transversely pulling the entrance film, which is scanned by one or more sensors The current position of the film and transmit it to the controller; the controller compares the measured actual position with the set position, if there is a deviation between the two, the controller will transmit a correction signal to the driver; the driver drives quickly The track at the entrance of TDO enables it to track the edge of the film in time. In this cycle, the EPC system keeps driving the track to reciprocate, so that no de-clamping phenomenon occurs. EPC structure and classification According to the different power devices of the EPC system, it can be generally divided into 4 types: electromechanical EPC, electro-hydraulic EPC, pneumatic hydraulic EPC and magnetic EPC. The structural principle of the electromechanical EPC system is shown in Figure 1, which is mainly composed of three parts: sensor, controller,
Industry professionals have compiled the possible failures, causes, and countermeasures of gravure printing films into a table for everyone to check and compare. It’s very practical, let’s take away the collection and use it. Name Phenomenon Reason Solution Adverse overprint In multi-color printing, the ink is printed on the first printed ink film, which will cause repulsion, and the second color will stick the first color down, resulting in reverse overprinting. The ink in the front is not sufficiently dried, and the ink in the back dries too fast, which is caused by high adhesion during printing. Generally, glossy inks are prone to overprint failure 1. Printing plate: (1) Engraving plate is easier to cause failure than corroded plate. (2) Increase the depth of the back color plate (in the case of reverse overprinting). 2. Printing stage: (1) Use fast-drying thinner to speed up the drying of the front ink. (2) Use a slow-drying diluent to slow down the drying of the subsequent ink, and at the same time reduce the viscosity of the ink without water flow lines. (3) The position of the squeegee of the back color is closer to the printing direction to reduce the printing pressure
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