Views: 0 Author: Site Editor Publish Time: 2023-02-14 Origin: Site
PVA high -resistance coating is safe and environmentally friendly and excellent cost -effective materials. Most friends have a deep understanding of K coating, that is, PVDC coating, aluminum foil, aluminum plating, and EVOH barrier materials, because everyone has used these materials for many years and is very familiar. Not much, so there are a lot of questions.
First of all, I will use the familiar high -resistance partition materials to compare what the PVA coating is and what are the characteristics.
1. The characteristics of PVA high -resistance coating
Common high -resistance materials PVDC, EVOH, aluminum foil, aluminum plating, silicon -plated, etc. From the perspective of material nature, PVDC and EVOH are organic high -resistance materials. Aluminum foil, aluminum plating, and silicon -plated are inorganic high -resistance materials. According to this division, PVA should be classified as organic high -resistance materials.
In terms of organic high -resistance materials, PVA is similar to the PVDC process, similar to the EVOH barrier performance. In other words, the PVA high -resistance compartments are also implemented with coating process. PVA has excellent obstruction of gas such as oxygen and carbon dioxide. If it is used separately, PVA will not help the water vapor resistance too much.
Compared with PVDC, the difference between PVA is:
① The range of substrates for PVA coating is wider
Including common types of printing and heat -seal substrates, BOPET, BOPP, BOPA, various PE and CPPs. Especially the good coating adaptability on the thermal substrate can better prevent the pollution of the packaging content of the packaging and the residual solvents after the printing and compounding.
② coating thickness
Because PVDC's combination of various substrates is relatively weak and requires primer coating, the thickness of PVDC coating is basically between 3 and 5 μ.
The PVA coating itself has good affinity with various substrate materials, and the thickness of conventional products is less than 1 μ.
PVDC coating is prone to yellow change, which affects the appearance of the material. The transparency and appearance color of the substrate after PVA coating have basically no change.
PVDC coating contains chlorine, which is incinerated and poisonous, and the film containing the coating cannot be recycled.
PVA coating can be burned and recycled.
In addition to the water vapor resistance slightly lower than the PVDC coating, the obstruction of PVA for gas such as oxygen and carbon dioxide is far better than PVDC coating.
Compared with EVOH, EVOH is a polymer of ethylene-ethylene alcohol. The blockage is directly related to the ethylene content and the thickness of the EVOH layer. Therefore, if you want to get a higher blocking performance, the cost must also increase accordingly.
PVA coating, because it obtains a pure polyvinyl film after the coating is coated, even if the thickness of the coating is less than 1 μ, as long as it achieves uniform and complete coating, its blocking performance is still very excellent. Therefore, compared with EVOH, the cost performance is higher.
At the same time, due to the above reasons, it is not easy to use EVOH as a high -resistance compartments, and it is not easy to reduce the thin film, and the PVA coating is okay.
The above is the basic characteristics of the PVA coating and other organic high -resistance materials. Compared with inorganic high -resistance materials such as aluminum foil, aluminum plating, silicon -plated, etc., theoretical level of oxygen resistance will be slightly inferior, but please please, please please, but please please, please please, but please please, please, please, please, please, please, but please, please, please, please, please, but please, please, please, please, please, please, please, please, please, but please, please, please, please, please, but please Everyone note that this is just the theoretical level.
However, from the actual application perspective, the biggest problem of inorganic high -resistance materials such as aluminum foil is that it has poor flexibility, does not have ductility, prone to cracks and breaks. Even aluminum foil, after making bags and pinching, it is prone to increase local breathability. In these respects, PVA organic high -resistance materials are more advantageous. Of course, this is not absolute.
Second, the blocking performance and application of PVA high -resistance coating
The reason why it is not absolute is because inorganic high -resistance materials can also be used for bottom coating through some organic materials to solve this problem with the method of protecting the protective layer. Just like PVA coating High -resistant oxygen high and hydrating performance is the same. However, the improvement of these properties also means increased costs.
The characteristics and applications of PVA coating are simply summarized. PVA coating gives the barrier function of gases such as oxygen, nitrogen, carbon dioxide and small molecular volatiles with good materials.
For the content of high oil content, prone to oxidation, metamorphosis, brown change, and aroma escape, it has a good protective effect, such as meat products, spices, small bread, small cakes, dried fruits, and tea extended product shelf life.
PVA coating is water -based coating. It has better safety and environmental protection. It can be used for microwave heating. Oil resistance, organic solvents and corrosion resistance are good, good ductility and flexibility, and rubbing multiple blocking performance has no effect.
Third, the cost of the cost of using PVA high -resistance coating film
Under the premise of achieving the resistance of the same level, the PVA coating film is obvious than the EVOH blocking film, and the cost advantage is obvious. Because it has been introduced above, EVOH's high -resistance characteristics are inversely proportional to the content of ethylene in the material, which is directly proportional to the thickness of the material. (Maybe this expression is not rigorous, everyone understands the meaning), so if you want to realize the amount of oxygen less than 5, you must ensure that you cannot cut corners. You should know this cost.
The PVA coating wants to achieve the amount of oxygen with less than 5, and the thickness of less than 1um can be achieved.
Therefore, under the requirements of the same blockage, the cost of PVA coating is definitely more advantageous than EVOH.
Compared with PVDC coating film:
Compared with PVDC coating film, it may be slightly more complicated. Because everyone buying a film is used to settlement according to weight. The PVDC coating is thick, large, and the actual coating rice is small. Therefore, in terms of tonnage, the cost of PVA coating is higher than PVDC coating.
1. Can I print it after PVA coating? Does it affect the composite performance?
PVA does not affect printing and composite after coating, provided that ink and water gum are not recommended. Both dry composite and solventless composite.
2. Can I apply PVA on PE? Is it okay to put water -based substances after applying it? If you can install water -based substances, can you disinfect it?
It can be painted on PE, and water -based substances are also possible. If Pakistan disinfection, we are not recommended in the field of Pakatani disinfection.
3. When PVA coating membrane is squeezed (gonorrhea process), what kind of resin material is more appropriate? What are the points to pay attention to related processing temperature, composite speed, adhesive layer thickness and other parameters?
EAA resin can be selected in the coating gonorrhea, and the specific process can refer to the aluminum foil gonorrhea composite.
4. What level of PVA coating blocking performance is about? Is there a proportion relationship between PVA's thickness and blocking performance (OTR)? If so, what is about?
Regarding PVA coating blocking performance, you can refer to my introduction above. Various commonly used substrate structures are basically involved.
PVA coating thickening is indeed improved for blocking performance, but the increase will not be very obvious.
Taking PET as an example, for example, the current coating amount of drying can achieve the oxygen passage of less than 1 at about 0.6GSM. The amount of drying the coating continues to increase, which is difficult to achieve smaller oxygen values, and the cost will increase a lot a lot. Therefore, it is necessary to consider a cost -effective issue.
Of course, for some substrates, such as PE, the conventional oxygen permeability of about 2 is actually required. In fact, the oxygen transmittance data is smaller, and the thickness of the coating can achieve this effect. However, this will have higher requirements for equipment, crafts, etc.
5. What is the difference between PVA coating film and other blocking membranes such as PVDC, aluminum plating, silicon oxide obstruction membrane?
In terms of application, as far as the substrate level is concerned, PVA can be well applied to the coating of heat -seal substrate, which is the biggest difference from the above materials.
As far as terminal application scenarios are concerned, specific analysis may be required. In general, the current PVDC coating film application field, PVA coating membrane can be basically available.
If the products using alumina silicon oxide are high, the PVA coating film is not suitable for use alone.
What is mentioned here is that in terms of conventional products, it does not involve boiling and cooking fields.
6. The cost comparison of PVA is compared with alumina, silicon oxide, EVOH, etc. What is the application cost?
Compared with the cost of EVOH and PVDC coating membranes, I also have a rough explanation in the previous introduction. You can refer to it.
It is not easy to say for alumina and silicon oxide. Because the product levels of alumina alumina are different, and the use of targeted use is also different. For example, some levels of alumina product customers are used for conventional aluminum -plated membranes. The cost is low, and the requirements for obstruction are not very high. This PVA will definitely be more expensive.
If the goal of using alumina and silicon oxide is to solve the requirements of higher oxygen resistance and the requirements for water vapor through high requirements, then PVA will be more affordable.
7. Does PVA belong to hydrophilic materials? What is the resistance of the high humidity? Is there specific data?
This problem also made some explanations in the above introduction. What needs to be added here is that PVA is a hydrophilic material. After the modification, the proper coating process can be improved. For example, the data I give you before. Use or directly contact with water.
8. Do I need an AC agent between coating and substrate?
9. What is the PVA aggregation used in coating? Low gathering, middle gathering, high gathering or super high gathering? In the case of contact with adhesives, how does it perform, and has it found a phenomenon that affects each other?
The problem of aggregation is because I am not a high molecular major, and I really don't know too much, sorry.
As for the contact with adhesives, the current commonly used dry composite and solvent -free composite adhesives will basically not affect.
10. I have seen PVA membranes in water transfer. What are the applications in packaging? Do I need to compound after applying PVA? What are the characteristics of PVA products compared with the K film (oxygen resistance, breathability, alkaline oil -resistant acid -resistant) characteristics?
Applications in packaging are mainly areas required to obstruct, such as food, drugs, daily chemicals, electronic products, metal rust -proof areas, etc. are all applications.
After printing, you need to make a composite.
In terms of obstruction, the above introduction is involved and can be referred to.
11. Does no solvent mean that it will not affect the performance of the substrate. For example, it will not become so crispy?
For the performance of the substrate, the mechanical performance of the original film after PVA is basically not changed.
12. For PVA, how much is the factor of the substrate?
The requirements for PVA coating for the value of the substrate can be referred to the Dain value requirements of the composite substrate.
What needs to be explained is that the quality of the PVA coating performance not only reaches the cause value, but has a direct relationship with the flat integration of the membrane surface and the surface precipitation.
So sometimes Dain is good, and the coating effect is not necessarily very good. Dain values are only one of the necessary conditions.