Study on optical brightener

Optical brighteners are typically dyes that fluoresce under ultra-violet light or higher rangers of the optical spectrum. If you want to see optical brighteners at work, get yourself a small battery-operated UV lamp and a bottle of Tide laundry detergent.

While to the eye Tide looks like a translucent liquid, under UV light, it's an opaque, white fluid. These dyes are washed into your cloths making colors look brighter.

As far as questions 2 through 3, it all depends on what you want to accomplish. How do we know the formula or what you're trying to achieve with it. You haven't told us.

As for 4, Google brightening dyes or optical brighteners. I'm sure you'll get hits on companies that make the stuff.

Hope this helped.

Dear Guru

Thank you for the explanation. Well, I have no idea on how should I start with my formulation. My ink formulation is a white colour, but what I concern is:

1)what quantity of brightener should I use in my white ink formulation?

2)how does this amount of brightener affect my white ink formulation?

Right now I am looking for different brands of brightener and do a short research on brightener. Have you do any research study on this? Can you advise me on how you do this?

Regards

Maimuki

I'm sorry, no I don't... but here's a suggestion:

1. Get several dyes.
2. Test each one for stability and compatibility with your ink.
3. If one or more are stable and compatible, then test for brightening, using different amounts. I would start with a very little bit and then raise the amount until it looks right to you.

I'm assuming you want to use the smallest amount necessary to save on costs.

Good luck!

Hi Vermin

I've done my testing, just to share with you a little. I tried with small amt and increase the amt of brightener. Apparently, by adding more brightener, it will not make ink look more fluorescent rather it has saturated at that particular amt and show symptons of not uniform dispersing of brightener. This mean only add amt until optimum and deg of fluorescence remain the same.

Rgds

Maimuki

Maimuki,

Thanks for getting back! Interesting! Most people just disappear, but it's nice to hear back and find out whether one's advice worked.

Yes, like anything you try to dissolve in a solution - first, does it dissolve; and, second; how much will dissolve before you can't put any more in.

Hello,

Optical brighteners (OB or OBA) or fluorescent whitening agents (FWA) will enhance the blue portion of the visible spectrum (mask yellow) by absorbing longwave UV (typically 350-390nm range) and re-emitting blue (typically 400-460nm range) in return. OBs functions best when viewed in sunlight or simulated sunlight because of the UV component. Too much addition will result in a green tint and the "green-out" amount varies by the chemical structure type. OBs are subject to fade by exposure to heat and/or light and again vary by structure, so be sure to run appropriate tests if initial results are good. While there are ~300 known OBs, only about 20-30 are actually produced commercially. Common ones are di-, tetra- and hexa-substituted sulfonated stilbenes, also benzimidazoles and coumarins. There are a few cationic types used in inkjet papers. The Color Index from the AATCC (USA) or the SDC (UK) lists most, but not all OBs. Stateside and Euro suppliers include, but are not limited to Ciba, Clariant, Kemira and 3V. Numerous producers exist in China and India if you need to procure in the Pacific Rim region. OB's can be enhanced by the addition of polyols like PVOH or PEG.

Z-engineer

Hi

Wow! Very technical reply fro you, but it is veri informative for me, I am new in polymer so I still need some time to digest your term. Right now, I have tried one supplier from India, have you ever heard before of Dimachema?

I've tried my experimental work from Dimachema, it does enhance the level of whiteness and I use colour meter for measurement and observe under a colour box of blacklight UV. However too much adding of OB content, it will not further enhance the white rather it has reach that limit of whiteness. Am I right to say that? Can I also say that OB is a form of white pigment? As I do know that the common white pigment used in market is titanium dioxide TiO2. TiO2 is more like a matt compared to OB.

May I know the full chemical of PEG? Are PVOH and PEG easily available as sample?

Hello again,

All OBs, at some addition level will max out or "saturate". This is because they rely on UV excitation to work, release blue light in return and this mechanism can only go so far in the real world subject to only natural sunlight or office light.

OBs are dyes, not pigments, and in some cases, if they precipitate out as a (un-designed) pigment, they will be quenched and can lose their UV fluorecence activity. TiO2, especially the rutile form, will quench OB fluorescence, so be careful of mixing certain quenching materials with OB. Specific non-aqueous OBs are designed for introduction into polymer melts where polyester fiber, as an example, needs it to maintain a white appearance.

PEG is polyethylene glycol, PVOH is polyvinylalcohol. Use a PEG perhaps greater than 4000 molecular weght and choose a low viscosity PVOH if working in aqueous media. These are common materials available worldwide.

Dimachema in China is one of a number of exporters there, but I guess they have a branch in India. If you have developed a good relationship, continue. Keep track of of the Color Index Number (C.I. #) or Chemical Abstracts Number (CAS #) of any candidate(s). This can sometimes be confusing because many OBs can exist as a free acid or some specific salt or salts. Also try to keep track of additional salt content, urea or extenders used in any OB, especially if it is supplied as a solution.

Brightness is often measured at 457nm, but of course, this does not reflect the full reception of the human eye. OB can do nothing for opacity, which a pigment like calcium carbonate, clay, barium sulfate or titanium oxide can provide. At times, a bright, but somewhat transparent material is not precieved as "white" compared to something using white pigmentation.

Z-engineer