The most popular way to realize high-performance P

2022-07-31
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Implementing high-performance PLA processing from the point of view

material handling from the point of view

recently, universal dynamics, a subsidiary of the famous Italian auxiliary equipment supplier Piovan group, launched two systematic solutions for PLA processing: PLA sheet processing and PLA bottle blank forming. The whole process of processing PLA materials is analyzed in detail. The author specially excerpts some key points for the industry processing reference

Bruckner transformed the bopla production line for taghleef industries

raw material receiving and storage

from the process point of view, the purchase, acceptance and storage of PLA resin is the beginning. From here on, appropriate disposal technology will have an important impact on the quality of final products

1. New PLA resins (such as products from NatureWorks) are generally crystalline products, which are dried to a moisture content of 400ppm before leaving the production unit

2. If the packaging box and lining are completely intact when the PLA is received, the amount of drying required is very small, but it still needs to be dried. If the membrane lining has been opened, it needs to be dried

3. New resins are usually crystallized for efficient drying. When the temperature rises to 140 ℃, the amorphous PLA will become sticky and caked

4. The crushed PLA or recovered PLA may be crystalline or amorphous. The fragments processed from transparent thermoformed products, trim wastes or cast sheets are highly amorphous. The fragments processed from stretched films or sheets are a mixture of crystalline and amorphous materials, while the fragments processed from fibers are highly crystalline

5. Before processing, verify with the resin supplier to verify the conditions of the resin to be put into the processing equipment, so that the process can be planned accordingly

6. If the conveying pipeline with too high speed is used for conveying, the resin pellets are likely to degrade during pneumatic conveying. PLA resin will form fine flow lines inside the piping system, which are generally generated at the elbow and close to the elbow

7. The reasonable unloading speed of the tank car shall be about 20000 pounds per hour, and the material speed shall be limited to 5000 inches per minute or less. The tank car driver manually operates the vehicle fan and valve, and sets the conveying system to complete the unloading of the vehicle. When the total root mean square g (RMS) value of acceleration is known in 5.3 of the 4 "type conveying pipeline, and the acceleration power spectral density formula is used in combination with the vehicle conveying device, if the fan speed and pressure are set high enough, 40000 pounds of raw materials can be unloaded in less than 1 hour. When operating in this configuration, fine powder or streamline will be generated each time

device layout

8 In the PLA extrusion processing industry, a good layout can improve the operation performance of the equipment. When selecting the equipment required for the extrusion production line, it is equally important to plan the available building area and purchase the equipment itself

9. At the beginning of the process, the location of material transportation and storage is the first step to be considered. The selected material conveying position shall be closely coordinated with the position of the extruder in the production line, so that the raw materials can be conveyed within a reasonable distance

10. The allocation of space for material preparation devices is the next focus. If the extruder is located near the material source, the dryer, crystallizer, crusher and mixing equipment should be located in the nearest area as far as possible. These machines are arranged near the extruder, where the operators prepare and run the production line and hope to seize the first opportunity as soon as possible. It will be very convenient to operate

pneumatic conveying system

the raw material processing system feeding to the feeding port of the extruder is an important part of each plastic extrusion system. When handling PLA, there are several points to pay attention to the common pneumatic conveying system

11. As far as possible, vacuum conveying process shall be used to convey materials inside the production line. The vacuum conveying system is adopted. Once the system leaks, only a small amount of indoor air will be sucked into the conveying pipeline. If leakage occurs in the high-pressure conveying system, the dust in the system will fly out from the leakage point and deposit in the production workshop

12. A properly designed transmission power unit shall be used to drive the air in the system

select appropriate constant volume blower and make the blower run at appropriate speed to produce the specified air flow. When this device is selected, it is only applicable to a single delivery pipe diameter, resulting in a specific resin delivery speed in the system

although many people think that the new granular material is dust-free, in practice, there is always a certain amount of fine powder in the material processing system, so the system should be managed to reduce the generation of fine powder as much as possible. The fundamental way to solve this problem is to select appropriate constant volume blower to carefully control the air flow through the system. By limiting the maximum speed of 5000 feet per minute (f/m) (about 1000m/min), the degradation of materials during pneumatic conveying can be reduced

13. Sufficient speed shall be maintained at the feeding end of the system to reliably suck resin at the feeding end of the system. The starting speed of about 3500f/m can ensure the normal operation of the PLA conveying system

process water cooling system

pla sheet extrusion process requires process water cooling system to ensure the normal operation of extruder and dryer

14. The extruder is equipped with a water cooling system in the feeding area and a cooling device for the hydraulic system of the machine. These devices and the return air cooling spiral pipe in the dryer can be operated in a water tower device

15. The polishing roller in contact with the hot resin during sheet extrusion needs cooling water to achieve sufficient sheet cooling rate

these requirements are the basis for determining the cooling water demand of the production line

mixing operation

pla sheet production line will generate a large amount of waste during operation, and the recycling of these waste materials is very important to sheet quality and product cost control

16. When running a single line system (only one extruder supplies resin to the die head), the amount of waste re fed into the system is generally 40%-50% of the total production

17. Accurate and uniform mixing of PLA raw materials can ensure the smooth progress of downstream processes

depending on the products manufactured, the mixer shall uniformly mix the new materials with the crushed materials from one or more sources. Also use the mixer to mix the required color and other process additives

pla crystallizer operation

when processing PLA resin, the raw materials used in the extruder must be dried before melting. If it is not dry enough, the mechanical properties of the finished product will be reduced

18. Before drying, the PLA resin shall be crystallized to ensure the normal operation of the traditional hopper dryer

process drying system

a resin process drying is the most critical step in the preparation of raw materials. In order to make a good sheet, the process drying standard is to achieve a moisture content of 250PPM or less

20. The standard requirements can only be met under specific temperature, corresponding treatment time and air quality conditions. If any of the required drying factors is not met, or the dryness of the resin is not maintained, the product quality will be unqualified. For PLA, poor drying will degrade the product

21. Processors should be very careful when preparing and extruding PLA resin, because damage to the base resin is generally irreversible

22. The equipment for drying PLA is a dehumidification hopper dryer with optional function of low process temperature. There are four main factors in drying PLA. The first is that sufficient air flow is required to transfer heat energy to the resin and conduct sufficient gas exchange to take away all moisture. The second element is the dryness or dew point of the air entering the process drying hopper. The industrial standard is dew point -40 ℃. The third element is temperature. The applicable drying temperature of PLA is 150 ℃ -190 ℃. We recommend the lowest temperature that can achieve full drying, generally 150 ℃ -160 ℃. The fourth is the most important factor in the drying process, namely the drying hopper. The drying hopper looks very simple. There are also some very important factors to pay attention to, including selecting the appropriate hopper volume. Small hoppers may not be dry enough; If the hopper is too large, the material stays in the barrel too long. The distribution of hot dry air should also be considered in the design of processing hopper to achieve the most effective logistics drying efficiency. If the above four factors are fully met, the crystalline resin can be added for pre drying, and the extrusion system can be run to achieve successful production

switch from BOPP production line to bopla production line

with the change of traditional market structure, some companies may want to use traditional production lines to realize PLA processing. The original production line may process pet or PP. In August, 2010, Br ü cknerservtec (hereinafter referred to as Bruckner), a leading global supplier of double pull film system, helped an Italian BOPP manufacturer complete the transformation and installation of a production line

taghleef industries, the world's leading BOPP producer, and Bruckner company jointly transformed an existing production line of taghleef in Italy to produce bopla

Bruckner designed a special layout and provided the main components to be modified such as the existing extrusion system, casting device and TDO, as well as the parts and components required for the modification of peripheral equipment. In order to make the most efficient use of all these new components, the process control system has also been upgraded to the latest technology. Extensive tests conducted on the Brookner laboratory production line confirmed the configuration data of parallel processes. Bruckner is also responsible for supervising and guiding the installation and commissioning process of production line transformation. The new production line was put into operation on August 18th, 2010, and successfully started industrial production one week later

efficient biopolymer recovery system

s-gran-hd recovery device developed by NgR can realize high-performance recovery of PLA

recently, NgR company successfully developed a new technology for effectively recycling bioplastics. The recycling of biopolymers is generally considered to face great difficulties. Many experts even believe that plastics made from biomaterials cannot be recycled. The latest technology of NgR company has proved this understanding wrong

ngr company has focused on the "one-step process" from the beginning. With this process, the plastic will not experience high temperature in the recycling process. Most importantly, for the recovery of high-value bioplastics (biopolymers), it is more important not to experience high temperature. This is because the manufacturing cost of "natural plastics" made from renewable plant materials is two to three times higher than that of products made from crude oil. In addition, the typical NgR "one-step process" has high energy efficiency and low power cost during operation, which is also one of its highlights. Because of the high cost of raw materials, the return time on investment is very short, and the amount of waste produced in the production process is very small

ngojosefhochreiter, CEO of NgR, believes that this process has great potential: "in the manufacturing process, punching and cutting operations will produce a large amount of production waste. Our goal is to make these high-value materials be recycled and directly returned to the production process." However, the plan does not apply to bioplastics that have been sold to consumers: because bioplastics are biodegradable, they are usually composted

ngr found that biomaterials have increased significantly worldwide. Compared with crude oil-based plastics, bioplastics will become more and more important in the future. Europe and the United States have made great progress in biopolymer technology, and the potential market of NgR technology is likely to focus on these regions

josefhochreiter estimates that due to the increasing demand

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