Blister - Varnish Issue

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.

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.

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?

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/

Some materials react to light.

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.