Production technology and application of the hotte

Casting polypropylene film production process and application (Part 2)

IV. CPP film raw material

the production of CPP film should choose the resin of proprietary brand. Generally, the resin with melt flow rate (MFR) of 6 ~ 12g/10min is required to have a certain melt fluidity. As mentioned above, casting production resin has PP Homopolymer and PP copolymer, which is characterized by excellent impact strength and good heat sealing at low temperature. Table 3 shows the performance of several representative CPP brands

Table 3 typical brand performance of CPP film

mfr/g (10min) -1 density/g cm-3 tensile yield strength/mpa yield elongation% elongation at break bending modulus/mpa impact strength/j M-1 (23oC) Rockwell hardness (r scale) thermal deformation temperature/oc Vicat softening point/oc himont80 Shell 100. misu chemical 70.9027.5 Sumitomo chemical 70.9038 Sumitomo chemical 70.9034.3

other commonly used CPP brands are: PL Z 615A of shell company, FL 7015, FL 7012, FL 6314 and fl6416 of Singapore TPC company, cf3017 and XF 7523 of Japan mosu company, hf400, hf420, rf420t, rt401 T, tf420 and tf400f2 of Samsung integrated chemical company (SGC) of South Korea, sfc-150n and sfc-750 of Ho Nan Petrochemical Company of South Korea, h3400, r3400 and r3410 of Hyundai Petrochemical Company of South Korea, Yx37f of Montedison, Italy, kd701h of Borealis, etc

CPP brands found from relevant data include: fl80113, fl8111l, fl6315, fl6315g, fl6631 of Sumitomo chemical company of Japan, f150j and f450j of Nippon Petrochemical Company, 3878 (homopolymer, MFR up to 3710g/10min) of finathene company of the United States, hf400 (MFR 810g/10min) and hf510 (MFR 1110g/10min) of Samsung integrated chemical company of South Korea, etc. In addition, CPP brands used for BOPP compounding in Japan include ls711 and fd530 of Showa electric company and fcc6411a of Sumitomo chemical company

the requirements for raw materials of each layer of three-layer co extruded CPP are as follows:

(1) corona treatment layer (electric shock layer)

MFR is 6 ~ 12 g/10min

as a three-layer co extruded CPP film for composite substrate, blue wave is equipped with a variety of special experimental equipment for thermal insulation materials. In order to improve its adhesion fastness to ink and the composite strength with other materials, it must be corona treated. Using a large amount of plasma gas and ozone produced by the high frequency generator (h1f1g) to interact directly or indirectly with polyolefin surface molecules, polar groups such as carbonyl and amino groups are generated on the surface molecular chain, and their surfaces are roughened. At the same time, oil stains, dry moisture and dust can be removed. In order to meet the needs of printing and compounding, the surface wetting tension reaches 318 × 1024 n/cm is enough, but the film is always put aside for a period of time after forming, and the surface wetting tension will decay during this period, especially in the first ten days. In order to offset the above attenuation, the initial surface wetting tension value must reach 414 × 1024~418 × N/cm 。 Of course, the surface wetting tension should not be treated too high, otherwise the film surface will be brittle due to excessive oxidation, resulting in a decrease in mechanical strength

the decrease of surface wetting tension is directly related to the content of low molecular additives in the resin. The more low molecular substances, the greater the decrease of surface wetting tension. It is reported that when the wetting agent content is greater than 2000 μ At g/g, the surface wetting tension declines rapidly within a week. The content of wetting agent shall be controlled within 800 ~ 1200 μ Within g/g, the situation will be greatly improved. To sum up, the requirements for raw materials of corona treatment layer are: not only have certain anti adhesion, but also strictly control the content of low molecular weight substances. (2) The best MFR of the intermediate layer (core layer)

is 6 ~ 10 g/10min

the core layer must first have excellent rigidity, so the core layer is mostly made of homopolymer. The core layer of three-layer co extruded CPP film accounts for 60% - 70% of the total film weight. Whether the rigidity meets the requirements is directly related to the smooth progress of the next process. Secondly, the good optical properties (low haze and high gloss) of the three-layer co extruded CPP film also mainly depend on the core layer. In short, the superior performance of CPP film is basically reflected by the core layer, and the processing conditions of the core layer are the most demanding

(3) the MFR of heat sealing layer (non treated layer)

is 6 ~ 12g/10min

in addition to the characteristics of smoothness, anti adhesion, less precipitation, and less volatile components, the heat sealing layer must first have good heat sealing performance. As mentioned in the previous note of impact energy, multilayer co extruded CPP films can be divided into cooking type and non cooking type. There are two cooking types: one is for cooking at 100 ~ 120 ℃, and the raw material is random copolymer; The other is used for cooking and sterilization above 120 ℃, and the raw material must be terpolymer. It can be seen that general random copolymers can not meet all the requirements of CPP heat sealing layer, but the development of ternary copolymers and converters on electrical appliances have strong competitiveness

source: plastic packaging information