![<?echo $_SERVER['SERVER_NAME'];?>](/template/twentyseventeen/skin/images/header.jpg)
First, physical and mechanical properties of BOPa film
Pa film is an excellent packaging material, its main physical and mechanical properties are:
1. High tensile strength, good wear resistance, high softening point, high temperature steam sterilization of about 140 °C, high temperature resistance under dry conditions, general use temperature is -60 °C - 130 °C.
2, has excellent impact resistance and burst strength, easy to heat seal, can be welded by high frequency method.
3, good odor barrier, high moisture permeability, water vapor permeability increased with increasing temperature and relative humidity, can be used for vacuum packaging.
4. Good light transmission. After two-way stretching, the gloss is obviously improved, the mechanical properties are obviously improved, and the water vapor and air permeability are greatly reduced.
The biggest disadvantage of nylon film is its high water absorption. The mechanical properties and electrical properties are greatly affected by humidity. The physical and mechanical properties of the biaxially stretched nylon 6 film are shown in the attached table.
Project / Test Method / Performance (MD/TD)
Density / (g / m3) JISK-6758 1.15-1.16
Melting point / °C DSC 215-225
Tensile strength / MPa aSTM D882 250/250
Elongation at break /% aSTM D882 80-120/80-120
Heat shrinkage rate /% 120 °C*15' 0.5-1.0
Oxygen transmission rate / 『cm3/(m2.0.1mm.24h〠aSTM D1434 5
Operating temperature / °C -60~130
Second, the raw materials used in biaxially stretching Pa film:
Pa is generally called nylon, which is a crystalline plastic. There is a strong chlorine bond between molecules and molecules. Because this material has more crystals and stronger intermolecular forces, this is why Materials are more difficult to stretch.
At present, there are not many materials for producing biaxially stretched nylon films, and nylon 6 and nylon 66 are commonly used, but most of the general packaging materials are mainly nylon 6.
The resin used to produce the nylon film is generally used. If an appropriate amount of additives (two mainly silica) is added in advance during the resin synthesis, it can be used directly during production without the need for compounding and mixing.
The resin Pa6 which produces the nylon 6 film has a large hygroscopicity, and its intrinsic viscosity is about 3.5, and the moisture content in the raw material is generally 0.6%.
Third, biaxially stretched Pa film production equipment
The production equipment of the flat BOPa film is basically similar to the production equipment of the stretched BOPET film, and has a main machine from drying to winding, and also has auxiliary equipment such as waste recycling and slitting. However, due to the nature of the materials, the specific structure and parameters of some equipment are also different.
Generally, the drying device of BOPa uses a gas flow drying or vacuum drying device, the extruder uses a separate single screw, and the filter system uses a tubular filter. The die is automatically adjustable by the hanger type, and the thickness gauge is used for automatic feedback to control the opening gap of the lip. The cooling method generally adopts the method of adding a single drum and an electrostatic attached piece.
In the production of nylon film, the longitudinal pulling device is divided into three areas of preheating, stretching and cooling, and there are two transmission systems of high speed and low speed, and a pinch roller, etc., but its extraordinary point is that the longitudinal stretching temperature is low. There are fewer preheating rolls, no need to attach a heater when stretching, only a single point of stretching is required. Because the stretching temperature, heat setting and cooling temperature differ greatly, the transverse stretching machine should have a buffer zone in the front and rear positions of the shaping zone. The transverse stretching is relatively small, the length of each zone is different, and the preheating drawing is shorter. The heat setting area is longer. The cooling zone is generally cooled by natural wind.
Fourth, the production process conditions of BOPa film
Before extruding the sheet, the nylon 6 resin must be sufficiently dried, otherwise it will be seriously degraded during extrusion, bubbles appear on the sheet, and the film will be anomalous, such as atomization, which affects the properties and film formation of the film. Usually, the drying temperature is about 90 °C. The moisture content of the resin after drying is <0.1%. The dried nylon 6 is extruded at 240-260 ° C, and the melt is passed through a filter, a metering pump, a static mixer, and a handpiece to a cooling drum surface of 20-40 ° C to form a sheet having a good thickness. . The nylon 6 sheet was longitudinally stretched at a temperature of 45 to 55 ° C, and the draw ratio was 2.5 to 3.0. After stretching, the film was cooled at a temperature of about 30 ° C, and then entered into a transverse stretching machine. After 70-80 ° C preheating zone, and stretched 2.5-3.0 times at a slightly higher temperature, heat setting treatment at 200-220 ° C, and finally natural cooling, to produce the desired nylon film .
Due to the strong hygroscopicity of nylon, the mother rolls wound on the production line should be protected against moisture and cut as soon as possible. The cut products must also be packaged with moisture-proof, moisture-proof materials (such as aluminum foil) to prevent moisture absorption and performance degradation.
Printing, aluminizing, etc. require a nylon film with a large surface tension, which needs to be corona treated after stretching to increase the surface tension of the film from 0.4 kN to 0.56 KN.
Flame Retardant Pants,Flame Resistant Pants,Fire Resistant Pants,Fire Retardant Pants
Xinxiang Worldbest Patron Saint Co., Ltd , https://www.xxhyhsworkwear.com