Linear low-density polyethylene grass silage film
DATE：2022/10/6 9:32:57 / READ： / SOURCE：This station
Linear low-density polyethylene grass silage film
If polyethylene grass silage film (bag) is used to store freshly harvested grass, the original nutrients and moisture of the grass will still be kept after six months. This method of bagged grass storage is to use anaerobic fermentation during storage to convert starch components in some grass into lactic acid, so that livestock prefer to eat.At the initial stage of grass packaging in the bag, cell respiration oxidizes sugar and consumes oxygen in the sealed bag, forming an anaerobic environment (at this time, oxygen bacteria gradually stop their activities and anaerobic bacteria continue to multiply). Lactobacillus fermentation is produced under anaerobic conditions. Therefore, it is the key to the quality of the film for bag making to require the grass storage bag to maintain an anaerobic environment.
Polyethylene grass storage film (bag) shall have the following properties.
① The strength of the film is required to be relatively high. It should be ensured that the grass will not be damaged during storage, and it has good oxygen resistance to form an anaerobic environment in the packaging grass bag.
② The film bag shall have good sealing performance and shall be able to keep unbroken under low temperature (winter). ③ Proper heat preservation. The film should have low light transmittance to avoid heat accumulation in the bag and keep the temperature in the bag appropriate.
(1) Raw material selection and formula
① Formula of single layer polyethylene forage silage film forming material Single layer polyethylene forage silage film forming material, the main raw material is linear low-density polyethylene, and the reference formula for combination with other auxiliary materials is as follows (weight).
75 portions of linear low-density polyethylene (LLDPE, MFR=12g/10min), 25 portions of low-density polyethylene (LDPE, MFR-1.2g/10min), 4 portions of white masterbatch (40%~60% of masterbatch), and 4 portions of anti-aging masterbatch.
② Polyethylene grass silage composite film forming material formula Polyethylene grass silage composite (two-layer) film forming material, outer layer white film forming material, mainly by line
Linear low-density polyethylene grass silage film
If polyethylene grass silage film (bag) is used to store freshly harvested grass, the original nutrients and moisture of the grass will still be kept after six months. This method of bagged grass storage is to use anaerobic fermentation during storage to convert starch components in some grass into lactic acid, so that livestock prefer to eat.
At the initial stage of grass packaging in the bag, cell respiration oxidizes sugar and consumes oxygen in the sealed bag, forming an anaerobic environment (at this time, oxygen bacteria gradually stop their activities and anaerobic bacteria continue to multiply). Lactobacillus fermentation is produced under anaerobic conditions. Therefore, it is the key to the quality of the film for bag making to require the grass storage bag to maintain an anaerobic environment.
Polyethylene grass storage film (bag) shall have the following properties.
① The strength of the film is required to be relatively high. It should be ensured that the grass will not be damaged during storage, and it has good oxygen resistance to form an anaerobic environment in the packaging grass bag.
② The film bag shall have good sealing performance and shall be able to keep unbroken under low temperature (winter). ③ Proper heat preservation. The film should have low light transmittance to avoid heat accumulation in the bag and keep the temperature in the bag appropriate.
(1) Raw material selection and formula
① Formula of single layer polyethylene forage silage film forming material Single layer polyethylene forage silage film forming material, the main raw material is linear low-density polyethylene, and the reference formula for combination with other auxiliary materials is as follows (weight).
75 portions of linear low-density polyethylene (LLDPE, MFR=12g/10min), 25 portions of low-density polyethylene (LDPE, MFR-1.2g/10min), 4 portions of white masterbatch (40%~60% of masterbatch), and 4 portions of anti-aging masterbatch.
② Polyethylene grass silage composite film forming material formula Polyethylene grass silage composite (two-layer) film forming material, outer layer white film forming material, mainly by line
-407 - Manual of empty extrusion molding technologists
Type I low-density polyethylene resin is mainly used, and some auxiliary materials are added. The composition reference formula is as follows (weight). 100 portions of linear low-density polyethylene (LLDPE, MFR-12g/10min), 4 portions of white masterbatch (40%~60%), 4 portions of anti-aging masterbatch, and appropriate processing aids. The main raw materials for forming the black film of the inner layer of the composite film are LLDPE and LDPE mixture, and the auxiliary materials are mainly black masterbatch. The composition formula is as follows (for reference only) (quality). 60 portions of low-density polyethylene (LDPE, MFR-12g/10min), 40 portions of linear low-density polyethylene (LLDPE, MFR-1.2g/10min), and 4 portions of black masterbatch (40%~60%).
(2) Production process sequence
① Production process sequence of single-layer polyethylene forage silage film a. Preparation process sequence of masterbatch
Pigment or other additives are measured after grinding, and LLDPE materials are measured → mixed evenly → granulated after mixing in the extruder
b. Production Process Sequence of Single layer Polyethylene Grass Silage Film
LLDPE, LDPE and masterbatch shall be measured separately according to the formula → plasticizing and melting in the mixing and uniform extruder → molding tubular film blank → blowing film blank, air cooling and temperature setting → traction → coiling
② Production process sequence of double-layer polyethylene forage silage film
LLDPE and masterbatch are measured separately according to the formula → mixed evenly → plasticized and melted by the extruder
LDPELLDPE and masterbatch shall be measured and mixed evenly according to the formula → extruding machine plasticizing and melting mold forming composite membrane tubular membrane blank → blowing membrane blank, air cooling and cooling shaping → traction → coiling
(3) Extrusion and blow molding process of polyethylene grass silage film Extrusion and blow molding process requirements of polyethylene grass silage film are the same as that of ordinary polyethylene composite film, no matter the equipment or the process temperature of extrusion and blow molding materials. As shown in Figure 6-31, it is a mold structure for composite film forming, which can be used for reference when selecting composite film forming mold.
6.2.16 High polyethylene film
(1) Application Characteristics of HDPE Film - 408 - Chapter 6 Plastic Film Extrusion Molding
① High density polyethylene (HDPE) film is widely used because of its high strength and good toughness. The thinnest film can be blown to 7~25pm; The strength of the film is much higher than that of LDPE film. When applied under the same conditions, it can be about 40% smaller than the thin thickness of LDPE film. See Table 6-26 for the performance comparison between HDPE film and LDPE film. The film is easy to be oxidized and brittle in contact with oxygen.
(2) High density polyethylene film application High density polyethylene film is mainly used for various foods (including cold and hot foods), textiles, industrial products and agricultural product packages
Install. In addition, it can also be used as a composite film of wood and paper.
(3) Extrusion Blow Molding Process of HDPE Film
① The raw material selected for extrusion of plastic film has a resin density of 0.947~0.952g/cm and a melt flow rate (MFR) of 0.08~2g/10min. Melt flow rate
(MFR) The common value is generally not greater than 01g/10min.
② Equipment conditions In order to improve the production efficiency, the new screw with barrier structure should be selected as far as possible for the equipment used for extrusion blow molding of high-density polyethylene film; The feeding section of the barrel shall be able to cool down fully, and the inner surface shall be provided with longitudinal grooves; The mandrel in the forming die is of spiral structure, and the die lip clearance shall be adjustable between 1.2~1.5mm.
③ Process temperature: barrel temperature: 140~160 ℃, 170~190 ℃, 190~210 ℃; The mold temperature is 200~210 ℃.
(4) Key points of process operation
① The resin with high molecular weight and low melt flow rate shall be selected for extrusion blow molding of HDPE film, which has good melt strength and stable production of blown film bubble. Generally, resin with a melt flow rate of 0.03~0.08g/10min is commonly used.
② The production thickness of HDPE film is mostly in the range of 8~30pm, the bubble blowing ratio is about 4, and the tensile ratio is about 5; When producing ultra-thin film, an internal foam stabilizer can be added if necessary.
③ The extrusion plasticization temperature of HDPE resin is higher than that of LDPE resin. Pay attention to the temperature control should not be too high to avoid the degradation of raw materials, carbonization of molten materials, and small needle points of products.
④ Extrusion blow molding HDPE resin, the screw length diameter ratio shall not be less than 25, the compression ratio shall be 3~4, and 80/100/80 mesh filter screen shall be added in front of the barrel.
⑤ The condensate line of HDPE melt blown film bubble is higher than that of LDPE melt blown film bubble (see Figure 6-32). The vertical and horizontal orientations of this film play a role at the same time, which is an important forming condition for the production of HDPE ultra-thin film.
(a) HDPE film bubble (b) LDPE film bubble (5) Quality requirements High density polyethylene
Figure 6-32 The quality requirements for HDPE and LDPE olefin films are shown in the standard GB/T
As specified in 12025-89 for comparison of bubble blowing methods, resin density shall be used
1 - Wind ring; 2 A membrane tube neck; 3 Polyethylene with condensate line of 0.941~0.965g/cm3
Chapter 6 See Table 6-12 for the quality standards of low profile and high profile of plastic film extrusion molding. The physical force generation performance of the film formed by extrusion blow molding of this raw material shall comply with the provisions of GB9687-88 standard (Table 5-11). See Table 6-29 for academic characteristics. Table 6-27HPE film thickness deviation of high-density polyethylene film for food or drug packaging (excerpted from B2019890.080 Note: dart quality refers to the test conducted on every 10 samples at the film surface, creases and stripes. If it is confirmed that the 330300270110120150 die gap is not broken, the impact test is qualified when the number of rubber damaged samples in the molding die is equal to or greater than 6.
6.2.17 High density polyethylene thin film conversion section 180 High density polyethylene thin film refers to the thin molding film with thickness of about 0.01mm formed with high density polyethylene as the main raw material. The appearance and handle of this film are similar to that of thin silk paper, and its strength, toughness and moisture resistance are good; The application amount of this kind of film accounts for more than 90% of the total output of high-density polyethylene film. Compared with the film of the same thickness of low-density polyethylene, it is of good quality and low price. High density polyethylene thin film is mainly used for various shopping bags, garbage bags and
Plastic film extrusion
(1) Characteristics of high-density polyethylene thin film
① Compared with low-density polyethylene film, the film has high strength and good toughness, which is only half of the thickness of LDPE film at the same strength.
② The film has good heat resistance, barrier property and moisture resistance. ③ Good processability and heat sealing. ④ Good printability.
(2) Polyethylene resin with density of 0.948~0.950g/cm3 and melt flow rate of MFR<0.1g/10min is used for raw material selection. For example, DGDA6098 produced by Sinopec Qilu Co., Ltd. and qualified products produced by PetroChina Daqing Petrochemical Complex
3304F0.1AC6100M and GF7740 produced by Liaohua can be used to produce HDPE thin films. In order to improve the toughness of the film, 20% linear low-density polyethylene can be added to the main raw material; In order to reduce the production cost and enhance the hand feel, a small amount of light calcium carbonate can also be added to the main raw materials.
(3) Equipment conditions Extrusion blow molding of high-density polyethylene thin film and common
The equipment and process sequence for extrusion blow molding of polyethylene film are identical. The thin film can be extruded and blown using a medium 45mm screw extruder. The screw structure is an equidistant gradual change type, with a length diameter ratio of about 25 ∶ 1 and a compression ratio of 3. The front end of the screw is provided with a barrier, and the inner hole of the feeding section of the machine is provided with a longitudinal groove type plasticizing part, which is more suitable for the melting and plasticizing of raw materials. The forming die shall be of spiral structure with mandrel, die diameter of about+40mm and die clearance of 1~12mm. Dalian Rubber and Plastic Machinery Factory and Beijing Plastic Machinery Factory can produce special units for HDPE film that cannot be blown.
(4) The temperature of each section of the raw material extruder barrel in the forming process: 150~170 ℃ in the feeding section, 180~200 ℃ in the plasticizing section, and 200~220 ℃ in the homogenizing section.
Forming mold temperature: 190~210 ℃. The flat extrusion and upward blowing method is adopted, the blowing expansion ratio of the membrane blank is about 4, and the pulling film speed is more than 30 m/min.
(5) Key points of process operation
① The temperature of molten material for forming film blank shall be controlled within the range of 200~240 ℃
② Pay attention to the relationship between the blowing ratio of the membrane blank tube and the film strength. If the blowing ratio is large, the film strength is high, but it should not be too large to avoid affecting the uniformity of the film thickness.
③ The film blank pipe neck extruded from the forming die mouth is high (generally greater than 5 times the die diameter). This is to allow the membrane tube to stretch at a lower temperature. To prevent the membrane bubble from floating, foam stabilizers shall be installed inside and outside the membrane bubble.
④ The quality standard of HDPE micro film shall refer to B/T1589HE blown film quality standard.
6.3 Extrusion molding of polypropylene film
(1) Properties of polypropylene film
① Polypropylene film is the lightest kind of plastic products. The film is transparent, no polypropylene color, tasteless and non-toxic.
② Good moisture resistance. Purpose
③ Good electrical insulation performance; Flammability, chemical resistance, good stability, corrosion resistance, environmental transparency, good stress cracking resistance; However, it is easy to age in contact with copper. Deformation.
④ Good abrasion resistance, good rigidity and impact resistance, but impact strength is sensitive to notch at low temperature. Gather two
⑤ The melting point is about 168 ℃; It can be used continuously at 110~120 ℃. Huan method production
⑥ Good processability, but high shrinkage, easy to stretch orientation.
⑦ Poor weather resistance and colourability. (2) Polypropylene film application Polypropylene film is mainly used to package various items, such as cold and hot food, chemicals, electronic equipment parts, clothing, etc., to make items damp proof and pollution proof; In addition, biaxially stretched films are also widely used in capacitors.
(3) Polypropylene film forming methods Polypropylene film forming methods include extrusion tape casting structure, extrusion blow molding, stretching after extruding film blank and composite after extruding film. ① The film formed by extrusion tape casting is a film (CPP film for short) made by using a T-shaped (or coat hanger shaped) molding die after the PP material is plasticized and melted by a single screw extruder, extruding and casting the film onto a roller that rotates steadily at a flat speed, and cooling and shaping.
② The extrusion blow molding method is used to form the film by extruding the plasticizing melted material out of the machine and forming the mold
Author：admin