Shrink Sleeve Solutions Shr the long molecula


the long molecular chains in the surface of the film and oxidises it – this allows the ink to bond securely. The process is harmless to the substrate as it effects only a microscopic


only a microscopic layer at the surface and changes neither the strength nor appearance of the film.


Q:: Does the print process affect the need for or type for corona treatment? KM: Fundamentally


KM: Fundamentally, no it doesn’t.


to be more precise the variable in the equation is the substrate. While all synthetic materials are surface treated at the extrusion stage, it’s important to remember that two pre-treated rolls of the same material from the same supplier may not be consistent throughout their length or width, which is why you need to surface treat immediately prior to printing.


y, no it doesn’t. The issue, or e the variable in the equation


the extrusion stage, it’s important two pre-treated rolls of the


m the same supplier may not be hout their length or width, which o surface treat immediately prior


Q:: What other factors affect a film’s ability to perform consistently?


KM: There is one intrinsic issue and that is with the additives that are sometimes used in the manufacturing process.


g


ntrinsic issue and that is with are sometimes used in the ocess. These can migrate


throughout the film, and not necessarily in an even way, and then affect the chemical composition of the surface being treated.


p


and storage issues, can cause the dyne level of the ped by the time it’s delivered to the


m, and not necessarily in an even ct the chemical composition of g treated. This, along with transport , can cause the dyne level of the


film to have dropped by the time it’s delivered to the printer/converter. Excessive heat, cold and humidity ct the film during storage, so it’s


will adversely affect the film during storage, so it’s t it gets used within the date


recommended by the supplier.


vital to ensure that it gets used within the date recommended by the supplier. One piece of advice we give to everyone is ‘always dyne test the material before you use it’.


Q:: Looking ahead


Looking ahead, how will surface treatment cope with the new and more complex substrates being developed?


d, how will surface treatment


w and more complex substrates ?


KM: Since we invented corona process and have constantly developed surface treatment we have always been one st


always been one step ahead of the market. corona the answer to all applications?


not all. Some of the latest substrates have been developed to produce ‘unique’ products, typically using special inks and lacquers, lamination, multi web applications a


web applications and other techniques to produce 


nted corona process and have ped surface treatment we have tep ahead of the market. Is r to all applications? Most, but he latest substrates have been duce ‘unique’ products, typically and lacquers, lamination, multi and other techniques to produce


ne is ‘always dyne test the material


ctors affect a film’s ability to ntly?


process affect the need for or reatment?


r chains in the surface of the film is allows the ink to bond securely. mless to the substrate as it effects c layer at the surface and changes th nor appearance of the film.


sophisticated packaging. The constituents of these substrates require a chemical treatment process as well as a physical one – and in these instances Plasma treatment is necessary to ensure bonding. But that’s not the case for shrink sleeve production as its stands today.


nt process e instances ure bonding. e production


INK ISSUES INK I


Choosing the right substrate and preparing it correctly for its intended use is only part of the process of producing high quality shrink sleeves. The choice of ink is critical, as Amanda Jones (AJ), business development and marketing director at Paragon Inks explains.


paring it art of the ink sleeves. a Jones (AJ), g director at


Q:: What are the key rules and points that need to be addressed for the successful production of shrink sleeves using UV flexo inks?


that UV inks onds and do


ts that need production of


AJ: The fundamental point to make is that UV inks adhere by co-adhesive electrostatic bonds and do not interreact directly with the substrate being used. For UV flexo inks the rule is ‘less is more’.


rink Sleeve Solutions uents of these


lutions adhesion. It’s very simple but effective.


tape to the printed and cured surface securely and then peel it off. Any residual ink staining on the substrate indicates that it is not fully cured - clean, it is fully cured!


Q: What are the main issues that you have to troubleshoot?


AJ: The main one is poor adherence. main issues that you have to


curing normally gets the blame, but it’s often a combination of substrates giving false dyne readings that lead to incorrect surface treatment. This normally occurs when there are surfactant additives involved, typically used in PET and PVC manufacturing, which disperse unevenly and create adhesion problems by forming a thin invisible age, storage and suitability of


surface layer. The age, storage and suitability of V inks also need to be taken into


the substrate for UV inks also need to be taken into f these is causing the problem,


account. If none of these is causing the problem, t the volume of ink applied, and


ink applied, the thicker and heavier the layer, and this brings a greater risk of poor adhesion because the bonds sticking the ink to the substrate are weaker. The lighter and thinner the layer, the better the adhesion.


g y


Q:: What part does curing play in the process? AJ: It depends which process you are using. an ink properly is a balancing act between the wavelengths emitted by the lamps, needed to activate the photo initiators and absorbed by the different coloured pigments, also known as a pigment window. For example, the darker the ink the more difficult it is to cure using conventional lamps – this is the opposite with LED/UV. Curing the surface of the ink is easy, but the thicker the layer the more difficult it is to effect a complete cure.


e process?


using. Curing ween the eeded to rbed by


known as a arker the ink onventional


/UV. Curing the er the layer the e cure.


Q:: How do you test for a full cure?


AJ: There are various methods you can use on-press. Touching or rubbing the ink surface with your finger to see if its dry is the easiest and most common, as any smudging indicates insufficient curing. can also conduct a tape test, which w ill also check


can also conduct a tape test, which will also check 


 


n use on-press. with your finger common, as uring. You


ate being used. re’. The more e layer, and this because the e are weaker. better the


also its formulation.


you need to look at the volume of ink applied, and n. Not all inks behave the same so seek advice from your supplier.


with all substrates, so seek advice from your supplier.


Q: Are there issues after printing that converters need to be aware of?


mber of potential problems p problems


es after printing that converters e of?


AJ: There are a number of potential problems including ink flaking off after the shrink process, an embossed effect appearing, a dulling of certain colours and an inconsistent gloss effect to name a few – and each one needs to be analysed in detail to eradicate the fault – but they are all known issues and can be remedied if the converter, ink, and substrate supplier use their individual expertise and work together. Like all processes, there is a learning curve, but there is plenty of experience available to help make it work.


This has been by no means a fully comprehensive view of the shrink sleeve market, but in a sector that is attracting a great deal of interest and producing some highly attractive packaging options, narrow web converters that are considering a move away from ‘sticky’ labels can be reassured by the depth of knowledge and expertise available to tap into, and the security of knowing that there is plenty of room for growth.


o means a fully comprehensive sleeve market, but in a sector that t deal of interest and producing tive packaging options, narrow at are considering a move away can be reassured by the depth of xpertise available to tap into, and wing that there is plenty of room


ng off after the shrink process, ct appearing, a dulling of certain onsistent gloss effect to name a e needs to be analysed in detail ult – but they are all known issues ied if the converter, ink, and use their individual expertise and e all processes, there is a learning plenty of experience available to


s poor adherence. Incomplete ets the blame, but it’s often substrates giving false dyne to incorrect surface treatment. urs when there are surfactant typically used in PET and PVC hich disperse unevenly and create s by forming a thin invisible


simple but effective. Apply the d and cured surface securely and ny residual ink staining on the s that it is not fully cured - if it’s ed!


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