Special Effect Pigments/ Fragrance - FAQs
Reversible Photochromic Pigment
Q: What Long lasting outdoor application of photochromic pigment possible?
A: Yes, directly integrate photochromic dye into plastic materials. Then the photochromic effect may potentially last for around a half year outdoor (under sunshine)! Special technical know-how will be needed. If interested, please contact us.
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Reversible Thermochromic Pigment
Q: What is the colour changing mechanism of our thermochromic pigment?
A: The change of pigment colours successes via opening and closing the ring of the aromatic structure.
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Q: What is the processing condition of our thermochromic pigment?
A: As masterbatches, the processing is feasible up to 200°C with a max duration of 5 minutes. Otherwise, the thermochromic pigments would decompose, losing its colour changing effect.
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Q: How about the usual lifetspan of the thermochromic effect?
A: Duration of colour changing effect could be 4000-8000 times or 2 years if the thermochromic pigment is properly stored.
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Q: How should I store the thermochromic pigment at best?
A: Cool, e.g. 4°C and in the dark. Sunlight and UV light must be avoided.
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A: Thermochromic colours appear somehow glass like (little bit transparent) due to its organic nature (no exception worldwide). Thus, their colour appearances are not so strong as the usual pigments.
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Q: Which care should be taken for making a multi-stage thermochromic mixture?
A: The "realistic" thermochromic temperatures difference between 2 colours chosen have better to be more than 10oC in order to deliver the best multi-coloured thermochromic effect.
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Q: What is the pH working range of out thermochromic pigment?
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Q: Is there any special care should be taken when using thermochromic pigment?
A: Please avoid its contact with polar organic solvents such as alcohol and keton...etc.
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Q: Is it possible to print or dye clothes with thermochromic pigment?
A: Application of thermochromic pigment onto textile is possible via printing or something similar to finishing process in textile:
1. The thermochromic pigment can be mixed with printing paste and then printing the pattern you want on T-shirt (Silk screen printing).
2. A dying bath can be prepared by mixing thermochromic pigment together with the binder. Thereafter, the clothes need to be incubated in this bath for about 20 minutes and then sent for drying.
The drawback could be that the attachment is not so strong so that the thermochromic pigment may gradually detach after 10-20 times washes.
The thermochromic pigment is not a dye and only is possible to attach on the clothes by binders.
You can use the same binder as those taken for the usual pigments. Nevertheless, binders containing acetone and alcohol solvent, such as PU binder should be avoided, which may decompose thermochromic pigment.
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Q: Is thermochromic pigment toxic?
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Q: How to use reversible thermochromic pigment?
A: if not processing with polymeric materials, its use is the same as usual pigment. Please avoid polar organic solvents such as ketons and alcohols.
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Q: How to dissolve thermochromic pigment?
A: Thermochormic pigment will not and should not dissolve in any solvent. Once dissolved, the micelle structure will be destructed and the pigment will lose its thermochromic colour switching effect. Instead Thermochormic pigment disperses in water and organic solvents. The use of polar organic solvents to mix the thermochromic pigment should be avoided e.g. methanol, ethanol, acetone, butanone …etc. Please avoid using polar solvents. The solvent we most frequently utilise to disperse thermochormic pigment is cyclohexanone
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We recommend the use of cyclohexanone as a solvent on the following premises:
<1> The thermochromic pigment must first be mixed into the paint, coating or ink.
<2> The paint, coating reagent or ink must contain only a small amount of solvent, preferably cyclohexanone.
<3> If the viscosity of paints, coating reagents and inks mixed with thermochromic powders is to be lowered, we recommend to add cyclohexanone to lower the viscosity of the paints, coating reagents and inks!
<4> To ensure the efficacy of thermochromic effect, we recommend to prepare the paints, coating reagents and inks containing thermochromic pigment:
a. Prepare them only before use
b. Prepare as much as needed
c. Use up the prepared paints and do not store it
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Q: What is the ideal mixing behaviour of thermochromic pigment with the ink and paints for its application on the product surface?
A: To reach a significant colour thickness of thermochromic pigment (also photochromic pigment) on the product surface, the pigment content of 20-30% w/w in printing ink is recommended, whereas 15-20% w/w is suggested for paint and spray paint. Integrated into plastic product of 1.5 mm thickness, the thermochromic pigment content should be at least 1% w/w.
Reverse reversible Thermochromic Pigment
Q: Is it possible to have reverse reversible thermochromic masterbatch?
​A: No, it is impossible
Q: How to dissolve reverse thermochromic pigment?
A: Thermochormic pigment will not and should not dissolve in any solvent. Once dissolved, the micelle structure will be destructed and the pigment will lose its thermochromic colour switching effect. Instead Thermochormic pigment disperses in water and organic solvents. The use of polar organic solvents to mix the thermochromic pigment should be avoided e.g. methanol, ethanol, acetone, butanone …etc. Please avoid using polar solvents. The solvent we most frequently utilise to disperse thermochormic pigment is cyclohexanone
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We recommend the use of cyclohexanone as a solvent on the following premises:
<1> The thermochromic pigment must first be mixed into the paint, coating or ink.
<2> The paint, coating reagent or ink must contain only a small amount of solvent, preferably cyclohexanone.
<3> If the viscosity of paints, coating reagents and inks mixed with thermochromic powders is to be lowered, we recommend to add cyclohexanone to lower the viscosity of the paints, coating reagents and inks!
<4> To ensure the efficacy of thermochromic effect, we recommend to prepare the paints, coating reagents and inks containing thermochromic pigment:
a. Prepare them only before use
b. Prepare as much as needed
c. Use up the prepared paints and do not store it.
Irreversible Thermochromic Pigment
Q: Is there any special care should be taken when using thermochromic pigment?
​A: Pleaase avoid its contact with organic solvents such as alcohol, ether and keton...etc.
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Q: Is it possible to have irreversible thermochromic masterbatch?
​A: No, it is impossible
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Q: What is the mechanism of discolouration for irreversible thermochromic ink?
A: When the temperature of the irreversible thermochromic ink exceeds 60 ° C, the core-shell applied to the outer layer of the colour rendering reagent and the dye melts, and the colour rendering reagent reacts with the dye to initiate a chemical reaction, and then appears magenta colour (magenta 60 ° C as an example).
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Q: Why is the colour appearance after coating and drying is lighter than before?
A: The reason is purely the optical effect caused by water! The plane surface of the powder stack is rough, causing the incident light to scatter, making the observation angle insufficient due to the collected reflected light. This leads to a decrease in chroma; if water is added to the plane surface of the powder stack, the water will fill the pores and make the surface smooth. After the surface is smoothed, the reflection of incident light can be more concentrated, the light scattering condition is improved, and the observation angle is collected. Since the luminosity and the chroma increase, the visual colour becomes more intense.
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Q: Is there any MC fragrance in the form of masterbatch available?
A: Not recommended. Namely during preparing masterbatch, a very large porportion of fragrance added will lose its scent.
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Q: Fragrance masterbatch possible?
A: Making fragrance masterbatch is possible, however making no sense. Fragrance (perfume) mostly consists of several different volatile substances and evaporate rapidly by heating. Thus, it undergoes high losses during production of fragrance masterbatch. Taking PLA, whose processing temperature is around 180°C, as an example, preparing fragrance PLA masterbatch will lose ca. 50% of added fragrance.
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Q: How long could the smell of the fragrance in plastic products list?
A: Approximately 3 months if stored in an opened system. If in closed system, the effectiveness of the smell may extend to 6 months.
Q: What is the adding amount of fragrance to plastic products?
A: Usually 1% w/w
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Donna Polymer
R&D Support & Customised Production
