Are you looking for a material that changes colour with light?
OliKrom is a recognised player in the field of photochromic materials. We work for many industrial sectors: aeronautics, food, automotive, construction, cosmetics, defence, energy, luxury, medical, transport, etc.
Our team of photochemistry experts masters all the most advanced concepts in materials science and thermodynamics to design and produce the various families of photochromic pigments.
The main families of photochromes
A photochromic coating (from the Greek words photôs light and chromos colour) consists of a pigment/colourant whose optical properties switch according to the intensity of light.
OliKrom develops and produces photochromic coatings or materials based on two technologies:
Colour change at a defined light output, returning to the original colour when the light intensity returns to its original level. Adjustable colour, excitation wavelength, lightswitching rate and reversibility.
OliKrom, producer of photochromic technologies
15 years of experience
Our know-how is unique. We know and avoid the pitfalls frequently encountered with photochromic solutions (instability and/or fatigability of the phenomenon, non-optimal optical property,…)..
In general, a photochromic material is characterised by a thermodynamically stable form A which is transformed by irradiation into a less stable form B, with a different absorbance spectrum. This form can be converted back to form A, thermally and/or photochemically. Usually, for the majority of photochromic compounds, the stable form is colourless or pale yellow, and it becomes coloured upon irradiation (positive photochromism). Some photochromic compounds show a coloured A-form and a colourless B-form (negative photochromism), or reveal a reversible change between different colours.
A photochromic product adapted to your needs
Depending on your industrial specifications, we select organic photochromic pigments (such as stilbenes, camphoras, o-nitrobenzyls, osazones, semicarbazones, etc.), hybrid or inorganic derivatives (such as metal oxides, alkaline earth compounds, metal halides).
Each of these families has advantages and disadvantages that we share with our clients.
Our expertise in photophysics allows us to control the photochromic property by simple chemical modification to become reversible or irreversible “on demand”. We adjust the speed of photo-commutation, the threshold of colour change, the optical response of inks and paints to obtain colour change in the ultra-violet, visible and/or infra-red.
Reliable production of photochromic coatings
For all application areas, we ensure recurrent and reliable production. Our experience shows that each industrial application is unique. We know that the pigment/matrix combination is crucial to control the photochromism and its stability. The modification of the ionic bath of the pigment/colourant charge affects the relative position of the excited states and therefore the properties (wavelengths, colours, switching speed, process fatigability).
To this end, we produce our own pigments but only deliver the final formulation in the form of :
- photosensitive inks (UV, solvent) adapted to printing techniques (screen printing, pad printing, etc.)
- photochromic paints (acrylic, polyurethane, etc.)
- photochromic plastics (polyethylene, polypropylene, etc.)
Each production (inks, paints, masterbatches, etc.) is identified, traced and accompanied by a performance certificate co-constructed with our industrial partner.
Photosensitive materials: some examples of applications
In the field of ophthalmology, the uses of photochromic coatings are mineral or organic photochromic lenses, which darken in response to ultraviolet light.
Mineral photochromic lenses usually incorporate a silver halide compound (silver chloride, silver bromide, etc.) in their structure. When exposed to UV light, the silver-halide bonds break and the silver atoms combine, darkening the glass. The silver-halide bonds are reconstituted as soon as the UV exposure is stopped, restoring the clarity of the lens.
Organic photochromic lenses are usually coated with a layer of oxazines. The bonds in the molecules are broken by UV light and the lens darkens. The bonds are reconstituted when the UV is gone, restoring clarity to the glass.
Aeronautics, space, defence
The use of photochromic coatings allows the creation of future intelligent coatings, interactive with their environment: laser aggression, camouflage, etc.
The use of irreversible photochromic technologies allows the tattooing of parts by laser treatment (authentication, anti-counterfeiting, personalisation of an object, etc.). Compared to laser ablation, this approach has the advantage of modulating the colour according to the energy for the same photochromic paint or ink.
Reversible photochromic materials have uses as sensors, in particular to inform of repeated or prolonged exposure to ultraviolet light.
For example, playful objects that can change colour with light: labels, buggies, dolls, etc.
Scientific experts at your side
To support you “from the initial idea to the final product”, the experts in our three departments are at your disposal at every stage of your project: research and development, pre-industrialisation and industrialisation.
The Materials Department,
This research and development unit develops the photosensitive pigment adapted to your specifications: excitation wavelength and optical power, reversible/irreversible character, tilting speed, choice of colours, etc.
The Process Department,
the expertise of the formulation
This unit is responsible for integrating the pigment into the desired matrix (ink, paint, etc.) while preserving the targeted photochromic property with regard to your technical, economic and regulatory constraints.
from the kilogram to the ton
Our factory ensures the industrial production of photochromic inks and paints in compliance with OliKrom Inside quality requirements (ISO 9001 certification) and secure supplies.
Do you have a project? Need to produce a photochromic ink or paint?
Send us a message and our experts will get back to you as soon as possible.