Resin technologies for retort flexible packaging inks: as consumer preferences and the general desire of food packaging companies to be more energy efficient drives food packaging from steel and glass to flexible retortable pouches, finding inks that can
The bags were included in the Apollo space program at the end of 1960 and soon began to appear on grocery shelves around the country. (1)
A study estimated that the number of retort packages produced worldwide in 2011 was almost double the number produced in 2006. (2)
Interestingly, before returning to North America, anti-dry bags became more and more popular in Europe and Japan, and the North American market has been growing rapidly since the beginning of 2000.
The growth of Retort bag packaging has been welcomed by consumers: glass cans or metal cans can provide better taste and more nutritious food;
Reduced storage space and the ability to get a single storage
The dimensions section plus the improved storage of non-repeatable containers.
Food processors like productivity are achieved by reducing the containers for disinfection time and energy.
They also appreciate the tempting look of the retort bag, especially allowing consumers to see a new transparent version of the food inside.
Finally, the retort bottle is light in weight, convenient in transportation and more energy saving.
Although there are many advantages to the retort packaging, it also poses a huge challenge ---
Sterilization conditions usually work from 121 [degrees]C (250[degrees]F)to 131[degrees]C(268[degrees]F)
Also, depending on the food, the retention time can be up to 60 minutes. (3)Hot-
There are similar situations with filling technology.
The packaging must use materials that can withstand high temperatures, resist deformation, tear and layering, and maintain non-penetration of the ink through the bag and the migration into the food.
The ink used for distillation printing must be able to withstand a relatively high temperature and pressure while in contact with the steam without reducing the laminated structure of the ink or packaging.
In addition, the ink must be eco-friendly, suitable for flexo printing and dents, and can be used on a variety of film substrates, ideally compatible with a variety of solvent systems and traditional non-solvent systems
Dry distillation ink such as cellulose (NC)based inks.
Due to these challenging requirements
Performance ink adhesive resin.
This paper reviews the resinbinder technology of inks currently available for dry distillation packaging.
Until recently, flexible packaging for dry distillation packaging relied on a layer of aluminum foil as a barrier to reduce the migration of moisture, water vapor, oxygen and other gases through the flavor components and inkcomponents of the packaging.
These packaging films are composed of three layers: the outer layer of polyester (PET), polyolefin (PO)
Nylon/nylon (PA)film; the ink layer;
Blocking layer of aluminum foil;
The inner layer of pouring polypropylene (CPP)
Next to the food, a layer or layers of adhesive sticks everything together. (4)
In this case, Manyinks and resin work well, and aluminum foil is still a very good barrier layer that is widely used today for retort bags.
The microwave and transparent bag eliminates the foil and facilitates a transparent and colorless barrier film.
This film is either made of a polymer with good barrier properties, or a transparent coating containing carrier polymers such as EVOH, or a metal oxide layer such [Al. sub. 2][O. sub. 3]
SiOx based on ordinary polyester, olefin and polyamide films. (5)
The coated film has excellent barrier properties, but it is usually difficult to attach to traditional dry distillation inks.
Ink migration through transparent packaging materials is largely influenced by the film structure, thermal reduction process conditions and resin adhesives, although other low molecular weight ink components, such as adhesion enhancing agents and dispersing agents also help to migrate.
This resin should not contain any toxic substances, nor should it contain substances that are easily migrated to food by packaging laminated structures.
Modern resins are designed to minimize the share of low molecular weight molecules to reduce the chance of migration. (6)
In the worst case, the ink resin is usually calculated to ensure that it does not exceed the specific migration restrictions specified in the applicable FDA and or European regulations.
In addition to taking into account the standard distillation process temperature and pressure, other factors should be considered for the new ink resin.
These are the effects of high humidity: steam and hot water can lead to a reduction in ink composition and accelerate migration.
Consumers also put additional requirements on the performance of ink resin: microwave and oven heating and re-heating packaging is another obstacle that must be overcome in ink and packaging design.
Finally, it is possible for ink to enter the food --
Turn off during printing.
Resin must have good resistance to congestion (
Pressure transfer, for example when storing on ina rollers waiting for future steps in the manufacturing cycle)to the inks.
When the ink is not fully dry (
This also happens when using the wrong solvent)
Ink can be transferred to food before placing an external conservation ecology
It was layered even before the bag was made, filled and heated. [
In conclusion, the ink adhesive resin must give the following properties to the ink used in the dry distillation packaging: * excellent adhesion on the printed substrate (
Onbarrier movies in particular).
* The selected adhesive has a high enough laminate adhesive strength.
* There are enough laminated adhesive strength before, during and after the distillation process.
* Excellent square resistance (to resist high-
* Excellent high temperature stability--
There should be no \"bleeding\" or any chemical decomposition of the ink adhesive.
* Good chemical resistance and hydrolysis stability.
The key components in the existing dry distillation resin technology dry distillation ink are resin, which disperse pigments to produce color features and ultimately combine the ink with other ink layers as well as adhesives and film substrates.
After years of use, many resin chemistry have proven themselves, although most widely available technologies have knockoffs for retort applications.
Among the most commonly used resins are nitrocellulose, vinyl, polyamide and polyurethane.
* Nitrocellulose: NC has been used as a general ink for ink adhesive resin for many years, usually in total with polyurethanebinders.
Nitrate cotton is easily dissolved in acetate and alcohol, which makes it common in both concave and flexo printing systems.
However, due to its relatively low decomposition temperature (160[degrees]C-170[degrees]C)
Moreover, due to the harsh hydrolysis conditions of the distillation process, the use of nitrocellulose dry distillation ink is limited.
Although the modern dry distillation ink no longer uses cellulose, this polymer still plays an important indirect role: Due to its wide use, any dry distillation ink must be sufficient NC-
Compatible in order to print from distilled togeneral does not require a lot of cleaning.
* Polyethylene resin: The most common type of vinyl resin used in dry distillation ink is poly (vinyl butyral)resins (PVB)
And PVC (PVC)(i. e.
Polymer of vinyl chlorine and vinyl acetate).
PVB ink adhesive resin is a polymer of vinyl tinaldehyde, vinyl acetate and vinyl alcohol, used in a customized scale to provide the right performance and form a transparent film.
As we all know, the thermal stability of these resins is relatively poor (
Especially in an acidic environment)
Although thermal degradation occurs at a higher temperature than during a typical distillation process. (7)
It is well known that these resins have excellent adhesion to PET and PA films and are therefore commonly used in dry distillation inks.
Main disadvantages of Pvb-
Based on the ink, they still need adhesion agents and they are usually not compatible with NC-based inks.
This inconsistency results in excessive cleaning of the printing press during operation, resulting in waste and increased costs.
These resins are also more difficult to handle and usually need to be common
Resin used to improve color strength.
PVC resin has long been used in inks for retort applications.
Modern PVC resin performs well on ordinary and coated films without adhesive additives;
They produce excellent print quality at a low solvent retention rate and can be laminated with most adhesives.
PVC inks, however, have two disadvantages: they are only soluble in ester and ketone and therefore are not suitable for flexo printing.
Chlorine content also makes PVC ink difficult to handle and expensive.
* Polyamide: The most commonly used polyamide (PA)
Ink resin is made by condensation reaction of difunctional amine and dipolyfatty acid.
Over the years, these resins have been widely used in North America.
They are usually used with the CAB (
Cellulose acetate)and poly(vinyl butyral)(PVB)co-resins.
PA resin provides excellent adhesive strength on many substrates and has excellent printing suitability similar to NC-based systems.
Can be used for flexo printing and concave printing.
These inks have been used for some distillation applications, although they also have limitations of pvb resin as they also require adhesion agents, which makes them work with NC-based systems.
Because of this, during the operation of PA-, printing equipment often needs to be cleanedandNC-based inks.
* Polyurethane (PU): Polyurethane (PU)
The resin used today is mainly used as
Adhesives in NC, PVB and PVC systems.
The function of PU resin as a single resin is a relatively new development in the can-run ink system.
The inks based on these resins are fully compatible with NC inks and can be used with acetic acid or alcohol solvents. PU-
Although many products based on isocyanate require isocyanate Ester chains, if these products are based on aromatic ocyan salts, they usually have great potential in retort applications, and then, the heat and steam during the dry distillation process produce poor aromatic amine.
Many PU resins are super.
A dispersing agent or NC component for good dispersion of organic pigments.
One of the benefits of PU technology is good anti-congestion and excellent adhesion of non-adhesion agents.
The latest development of the next generation resin PU resin has led the product to appear to provide substantial improvements for dry distillation printing. (8)
The ink based on these fatty PU resin makes full use of the advantages of PU ink, while there is no aromatic Ester and n-butyl catalyst.
The new resin is designed to have a relatively high molecular weight and run as a stand
The separate ink adhesive has excellent adhesion and printing adaptability to the ink.
Although they do not need them, these resins are still in total with most
Resin and additives.
These resins are also good dispersing agents for organic and inorganic pigments, and are soluble inol and acetate, which makes them suitable for flexo printing and dents.
These resins have sufficient heat resistance and hydrolysis capacity during distillation, while excellent anti-clogging and maintaining high binding strength on a large number of coatings and uncoated films before and after distillation.
Most importantly, this type of ink resin can be used for printing on a metal oxide coating barrier film. [
Abstract: With the increasing importance of dry distillation packaging, printing technology is also developing rapidly.
According to distillation conditions and the use of printing machines and technologies, there are several resin chemicals that can be used for distillation printing.
The new technology of fat polyurethane seems particularly promising.
Suppliers of printers, ink bottles and resins should carefully evaluate each distillation system to create safe and effective packaging. References (1. )Ghani Al-Baali, A. G.
Mr. Farid Abdul. M.
Springer 2006 \"sterilized food in a Retort bag \". (2. )
Joint Development Company
\"Retort bag: 2006-
2011, \"a global study. (3. )G. L.
Robertson \"Food Packaging: Principles and Practices\", Taylor and Francis, P. 2005140. (4. )
For example, the laminated structure used in the retort bag seeref. 1, also see: M.
Henker, international flexo printing company14,Issue 4-2008, pp 6-8. (5. )
Usually, barrier polymer films, such as PCTFE films, are relatively expensive to use in food packaging, or do not have enough performance for applications, so metal oxide coated films are more commonly used. (6. )
Therefore, many inks are sold worldwide. www. eupia. org)
European and FDA requirements (www. accessdata. fda. gov)
Must comply with any applicable local regulations for food packaging materials. (7. )R. Liu, B. He, X.
Chen, Degradation and Stability of polymer, 93 (2008), pp. 846-853. (8. )D. Metla, A.
Journal of Polymer paint color, August 2009.
For information about Versamid PUR products for the retortable app, please contact Robert.
Lieberman, product group manager, dipolymer and resin, 1-215-628-1166.
Held By Dhara Metla and Alexander Polykarpov Cognis Corporation, technical manager of Alex is feature products-
Packaging and resin.
Dhara Metla is a development chemist at Connors, focusing on the development of new products for Graphic Arts and adhesives.