Caution for using Mirror ink

What is the recommended applicable substrate?

The applicable substrates for MIR-Ink are PC and treated PET (MIR ink does not adhere to untreated PET, eveb if it is a PET substrate).

However, adhesion varies depending on the grade of PC and treated PET. In addition, for hard coat materials and acrylic materials, it is necessary to individually select inks and check adhesion.

What is the recommended overprint ink?

Please use MIX-HF ink for MIR-ink for over printing. If other inks are used, the mirror effect will deteriorate.

However, for substrates with strong solvent resistance (treated PET), inks other than MIB and MIX-HF inks can also be used as a overprint ink.

What information do you have on how to handle inks that affect mirror effect?

Be sure to stir mirror inks before printing. Some of the components may be separated, but stirring will make them uniform. Insufficient stirring may cause streaking or unevenness.

Do not return ink to the container of unused ink after printing. Ink remaining on the stencil will cause aluminum to agglomerate with each other, and printing again may cause a decrease in mirror effect quality, as well as the occurrence of streaking and unevenness. The above problems may occur if used ink is used, so please avoid using used ink.

Regarding the supply of ink, it is more efficient to use ink by pouring ink little by little onto the stencil than to put the amount of ink required for printing on the stencil at once.

What is the information on printing conditions that affect mirror effect?

Printing pressure and doctor pressure are important in printing conditions. Mirror ink provides mirror effect and opacity by orienting aluminum pigments. Therefore, in order to orient the aluminum pigments, the printing pressure and doctor pressure should be set higher than for general solid inks.

Thicker film thickness (3μ or more) may cause delamination in the aluminum layers. In addition, mirror surface will be reduced, causing unevenness. As for opacity, thicker film thickness improves opacity, but if the aluminum pigments are well oriented, opacity can be obtained even with a thin film thickness.

Stable quality (mirror effect and opacity) of printed materials can be obtained by printing recommended conditions described in 1-2 Screen stencil, 1-3 Squeege, 2-2 Drying conditions, and 2-3 Printing conditions.

What is the information on drying conditions that affect mirror effect?

For non-solvent-resistant substrate (PC), mirror effect properties are greatly affected by drying conditions. This is especially true for PC molded products. The optimal drying conditions vary depending on the grade of PC resin used, molding conditions, etc.

Mirror effect can be obtained by initial drying at low temperature and subsequent drying at high temperature. (Initial drying at low temperatures suppresses the effects of solvent attack and improves the mirror effect because the aluminum pigments are well oriented.)

What is the information on substrate (base material) that affect mirror effect?

Drying conditions vary depending on the type of substrate.

In case of MI-51000 Mirror ink series, drying condition is 80℃, 30 min. for both PC and treated PET, but for PC, initial drying at low temperature followed by high temperature drying (80°C for 30 minutes) will give a more mirror effect.

What is the recommended preliminary test?

Be sure to conduct a preliminary test under similar printing conditions before printing on the main line. The preliminary test procedure is as follows.

1. Print mirror ink on the substrate to be printed on the main line (substitutes are not acceptable) and dry under the conditions described in the catalog.
2. Conduct test on mirror effect, opacity, and adhesion, etc.
3. If it fails, adjust the printing and drying conditions to obtain satisfactory results.

Repeat the above tests until appropriate conditions are found.

What is the recommended viscosity adjustment?

Mirror inks do not require dilution at the time of use. However, it should be stirred well before use.

What is the recommended screen stencil?

The finish of mirror ink prints varies depending on the type of screen stencil used. The items of a screen stencil suitable for printing mirror ink are stencil mesh, opening, line diameter, and emulsion thickness. Recommended conditions for printing stencil are a stencil mesh of T-300, a wide opening, a narrow line length, and a thin emulsion thickness (6 to 8 µm).

What is recommended environmental conditions?

When printing MIR-Mirror Ink series, please adjust the temperature and humidity to keep them constant as printing working conditions. Recommended conditions are temperature: 20-25℃, humidity: 50±5%Rh. If the printing working conditions become too hot or too humid, mirror ink absorbs moisture, resulting in a decrease in mirror effect and opacity, and stable printing is not possible.

What are some of the differences between mirror ink and general solvent ink that should be noted?

In order to provide mirror effect, the composition of Mirror Ink differs greatly from that of general solvent type inks.

The composition of mirror ink is mainly resin, aluminum pigment, and solvent, but the resin to solvent ratio is different compared to general solvent type inks. Therefore, there are differences in performance, such as printability, between mirror ink and general solvent type ink.