Oil and chemical resistance of PVDC LATEX (Source: Catalog of Dow Chemical Co.)
< 2. About PVDC Coated Films >
(1) Applications in Japan
PVDC coated films are used in wide range of applications, taking advantage of their excellent barrier property, flexibility, transparency, and heat sealability. Actual examples of the uses of PVDC coated films are shown in the following table.
Actual examples of packaging using PVDC coated films
||Structure of film
||Example of application
||Function of PVDC |
|PVDC coated OPP
||PVDC coated OPP/PE/LLDPE
PVDC coated OPP/PE/EVA
PVDC coated OPP (Both surface)
|Wieners, rice cookies, chocolate confectioneries
Pickles, devil’s tongue, dried foods
Oxygen gas barrier property
Moisture proof property
Odor proof property
Film processing property
High packaging suitability
|PVDC coated PET
||PVDC coated PET
PVDC coated PET/CPP
PVDC coated PET/PE/EVA
Hamburgers, meat dumplings
|PVDC coated ONY
||PVDC coated ONY/LLDPE
PVDC coated ONY/CPP
Boiled foods, pickled (salted) vegetables, fresh confectioneries, marine products (milled products)
Processed animal products
|PVDC coated Cellophane
||PVDC coated Cellophane/PE
PVDC coated Cellophane
|Pouches for pharmaceuticals
< 4. Precautions in Handling Asahi Kasei PVDC LATEX >
This part describes the main precaution on the occasion of using Asahi Kasei PVDC LATEX.
Before using PVDC LATEX actually, see the MSDS of the PVDC LATEX grade and confirm the protective instrument and the observable matter.
(1) Properties of Asahi KASEI PVDC LATEX
Both in the LATEX form and after coating, Asahi Kasei PVDC LATEX shows changes in the degree of crystallization of the resin due to temperature and time, and these changes have an extremely serious effect on the coating conditions and the properties of the film. For this reason, control of the storage of the LATEX, control of coating conditions, aging of the film after coating, etc. become important.
(2) Storage Temperature
Asahi Kasei PVDC LATEX should be stored in an indoor warehouse which can be maintained at a temperature of 3-30 ℃ . At temperatures of 0 ℃ or under, the product will freeze, and cannot be use even if thawed again. If the product is stored for a long period exposed to high temperature or direct sunlight, various problems ,such as precipitation, solidification etc., tend to occur easily.
(3) Storage Time
This product should be used quickly, because various problems, such as poor film formation, precipitation, coagulation, etc., may occur if Asahi Kasei PVDC LATEX is stored for a long period.
Because Asahi Kasei PVDC LATEX may coagulate due to violent stirring or friction (with the vanes and gland seal part of volute pumps, etc.), it should be transported by gravity or air pressure, or by a liquid transport pump with the lowest possible shear.
Because foaming will occur if Asahi Kasei PVDC LATEX is dripped from a high location or is violently stirred and time and trouble will be required to eliminate the bubbles, consideration should be given as much as possible to locating the liquid outlet near the bottom of the container, along the container wall, etc. Further, if drying occurs before the bubbles are completely eliminated, powdery coagulated materials will form and become mixed with the LATEX. For this reason, a filter with a pore size of approximately 100 μ m should be installed before the coating pan.
(6) Material of Container
Asahi Kasei PVDC LATEX is acidic (pH=1~5), containing hydrochloric acid. Therefore, polyethylene, polyvinyl chloride, or epoxy resin lined steel, FRP, glass lined steel, SUS316 stainless steel, etc. should be used. Because the LATEX will coagulate if iron or aluminum is used, these materials absolutely must not be used in piping, joints, tanks, and other parts which come into contact with the LATEX.
(7) Mixing of LATEX
Coagulation may occur if PVDC LATEX is mixed with other types of LATEX. When some different type of Latexes are used in the same equipments, the equipments should be fully washed before changing the type of LATEX. If there is a possibility of mixing, it is necessary to confirm whether LATEX will coagulate or not after mixing. At the same time, ingenuity should be used in order to avoid mixing as much as possible.
(8) Mixing of Additives, Etc.
When using with additives, etc., do not fail to perform a test with spare material and confirm in advance that there will be no abnormalities such as changes in viscosity over time, precipitation, etc.
When using Asahi Kasei PVDC LATEX by dilution with water, use water with a hardness of 300 ppm or less in order to avoid partial coagulation.
(10) Cleaning of Tools and Equipment
If tools, equipment, etc. which are used in handling Asahi Kasei PVDC LATEX are left unwashed, a resin film will form, hindering the next use. Therefore, equipment should be washed with water immediately after use. If dried resin has adhered to equipment, wash with tetrahydrofuran (boiling point, 66 ℃ , flammable). When using solvents, work should be performed wearing protectors, with adequate ventilation and consideration given to the danger of toxicity and fire. When removing dried resin which has adhered to the coater rolls and other important parts, the resin can be removed easily by using a soft metal brush and wooden spatula or hard nylon brush which will not scratch, and finally wiping with a solvent (tetrahydrofuran).