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Anonymous Poster #1

Blister - Varnish Issue

10/14/2015 3:46 AM

Hi all,

My company started printing for blister packaging upon a client's request. However, we noticed after roughly 5 months, our cards turned yellow-ish, shell and card isn't holding strong enough, it "opens up" easily i.e., the product falls out from the pvc shell and boxboard card!

We are using wax-free ink, tested the cards before printing for wax on surface, and testing viscosity of the varnish.

We are out of ideas how to solve this issue. Is there some mixture to add to the solvent for better strength and non-yellowing?

Appreciate any advice. Thanks guys.

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#1

Re: Blister - Varnish Issue

10/14/2015 6:28 AM

I point out that I have only a rudimentary knowledge of the process from a bit of work that I did for a company that used the process, so offer the following with that caution.

I would first be looking at the card composition.

Some cheaper papers have a higher acid content, and that causes yellowing with age and may also be contributing to the seal failure. Paper that is bleached to induce better whitening can cause higher discolouration with age.

Is the heat treatment process causing the discolouration, can the inks withstand the sealing temperatures?

How old are the cards before you process them, and are you keeping them in a low humidity environment? Both the seal coatings and the paper are hygroscopic and this will affect the seal. Any moisture in the card itself will rapidly turn to steam along the seal flange and likely cause sealing difficulties.

Is the seal failing or is the card delaminating at the seal?

Are the cards blister grade, ie clay coated etc?

Are both the card and the blister flange areas sufficiently coated with sealant, and are the sealants compatible with each other and also with the card and blister?

If using a water based sealant, you might consider changing to a solvent base as they are generally stronger. A cohesive sealant may be an option.

Are the heat and pressure settings correct for the job? Are you using preheaters?

Is the seal area sufficient for the package?

That's about all the thoughts that I have on the subject, hope it's more help than hindrance.

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#8
In reply to #1

Re: Blister - Varnish Issue

10/19/2015 10:55 PM

Thanks spades, you raised some really good points for us to look into.

Some cheaper papers have a higher acid content, and that causes yellowing with age and may also be contributing to the seal failure. Paper that is bleached to induce better whitening can cause higher discolouration with age. We never thought of acid contents in paper, would probably need to request from the paper supplier for a composition of it. We imported the paper in container, and only checked for wax previously.

Is the heat treatment process causing the discolouration, can the inks withstand the sealing temperatures? The ink we bought is specifically for blister, so it should be able to withstand sealing temperatures.

How old are the cards before you process them, and are you keeping them in a low humidity environment? Both the seal coatings and the paper are hygroscopic and this will affect the seal. Any moisture in the card itself will rapidly turn to steam along the seal flange and likely cause sealing difficulties. The cards are kept in air-conditioned room, when processed after 6 months, some, not all will have problems sealing. If the card is processed and subsequently stored in humid conditions, is it possible for the sealed card to be affected?

Is the seal failing or is the card delaminating at the seal? The card can seal, but after it cools down when we do quality tests, the card and the seal comes apart - is that seal failing or delaminating?

Are the cards blister grade, ie clay coated etc? Will check with paper supplier.

Are both the card and the blister flange areas sufficiently coated with sealant, and are the sealants compatible with each other and also with the card and blister? We checked the rollers for varnishing the cards. What do you mean by sealants compatible with each other and with card and blister? Thanks.

If using a water based sealant, you might consider changing to a solvent base as they are generally stronger. A cohesive sealant may be an option. We're using solvent. We considered changing to water-based as it is environmentally friendly. Never thought of cohesive sealant.

Are the heat and pressure settings correct for the job? Are you using preheaters? A client that we tested with is using a new range of machine, the timer settings is very short, for the client they want to seal the product fast to speed up production, but for us our sealing is not enough good enough for such short heating time. So we really need to improve to match their new equipment.

Is the seal area sufficient for the package? I would say its the normal blister style. Its for stationeries and lifestyle products (non-edible).

That's about all the thoughts that I have on the subject, hope it's more help than hindrance.

You have been of great help! Thank you very much for your patience.

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#9
In reply to #8

Re: Blister - Varnish Issue

10/19/2015 11:49 PM

Remember my point that I have limited knowledge of this process, so will offer only what I consider logical.

If the card is correctly varnished, I doubt that normal environmental humidity would affect it after processing, but trimming after varnishing can open up edges to moisture entry.

If the plastic separates from the card, then the seal is failing. If the plastic comes away with some of the card attached, then the card is delaminating.

The sealants need to stick to both the card and to the blister, and to each other. If any of these don't happen, the seal will fail. Some sealants don't work well on some plastics and varnishes.

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#2

Re: Blister - Varnish Issue

10/14/2015 6:54 AM

buy a competitors product and analyse the paper, glue etc. Is the yellow due to sunlight or do even items in the dark go yellow.
Why did you suddenly decide to enter this line of business, in shich you had no experience?Was the customer 'price shopping' and failed to give you samples of competitors products at first?

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#3

Re: Blister - Varnish Issue

10/14/2015 9:16 AM

Some thoughts:

1. Talk to the manufacturer of the varnish. They may have a different formulation that will be better suited for that use.

2. Talk to other manufacturers of varnishes/coatings to see if they have a coating better suited.

3. Talk to 3M about an adhesive to use between the printed card and the shell.

4. Make sure the inks and shell material are UV stabilized. Often when a surface 'yellows' over time the rapid aging is due to exposure to UV or short wavelength blue light.

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#4

Re: Blister - Varnish Issue

10/14/2015 10:57 AM

How long has your company been in the business of printing for blister packs?

How long has your company been in the business of printing?

How long have "you" been in the business of printing?

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#5

Re: Blister - Varnish Issue

10/14/2015 12:43 PM

Is the glue failing, or is the paper failing? What is the product in the package?

http://leadwise.mediadroit.com/files/18005Honeywell-Aclar-blister%20package-stability-whitepaper.pdf

http://www.pandpinc.com/

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#6

Re: Blister - Varnish Issue

10/14/2015 5:29 PM

Some materials react to light.

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#7

Re: Blister - Varnish Issue

10/15/2015 10:03 AM

ihave a extensive background in thermoforming, i do know that the blister cards are a specialized process and coating, my friends in the printing industry were not able to produce them for me, it is a specialized coating. perhaps try calling: Algus Packaging, Inc.

1212 E Taylor StreetDeKalb, IL 60115.they make the sealing machines and blisters.

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