Cold foil shrink sleeve label is easier than imagined
Time: 2020/9/24 15:20:08
How to ensure that there are no wrinkles in the cold stamping position
For cold stamping on shrink films, a
cooling roller is required on the printer, and a UV light box is also needed to
cure the adhesive used for cold stamping. This kind of adhesive is formulated
with a heat-shrinkable bonding material, and presses the hot stamping foil and
the printing material together through a hard pressure roller and a laminating
device. In addition, an electrochemical aluminum unwinding and waste foil
rewinding device is required to complete the hot stamping process.
Most shrink sleeve labels use acrylic-based
cold foil adhesive, but when the label shrinks on the container, the adhesive
will cause the shrink sleeve label to wrinkle, so it is necessary to ensure
that the adhesive has the ability to shrink. K-Laser and UVitec can provide
adhesives with shrinkage capabilities. At the beginning of printing, an anilox
roller with a screen count and cell volume of about 500lpi/5bcm is required.
Once the printing settings are optimized, it can be replaced with an anilox
roller with 600lpi/4bcm.
If cold hot stamping is performed in areas
with a relatively large shrinkage rate, texture patterns such as diamond-shaped
or tapered lines can be used to ensure that the hot stamping foil does not
crack when it shrinks.
How to achieve fine cold foiling
Not all embossing rollers are the same.
Cold stamping requires an embossing roller with a relatively high hardness to
ensure a fine hot stamping effect. If you want to confirm whether the hardness
of the embossing roller is appropriate, you can try to squeeze it with your
nails. If the surface of the embossing roller is deformed during squeezing, it
means that its hardness is not enough to achieve fine hot stamping of details.
Generally, the hardness of the pressure roller used in cold ironing is between
85 and 90.
Cold foils that can be applied to ordinary
labels can be used for cold foiling of shrink sleeve labels, especially
transparent holographic foils. But keep in mind that the ink and cold foil glue
of the shrink sleeve are printed in the back printing method, that is, the
printed image is viewed through the shrink film. Transparent primer is suitable
for colored foil and holographic foil, which can ensure the best transparency
of the film, so that the hot stamping pattern looks more dazzling.
For hot stamping of bright silver or gold
foil, the more common press speed is 500 feet per minute. Holographic cold
foiling generally achieves the best flicker effect when the speed is 200-325
feet/minute. Holographic embossing hot stamping is limited to the occasions
where the shrinkage rate is small, because the embossment will produce
unsightly distortions when it shrinks. Whether to use bright silver or
transparent holographic foil depends on the design needs. The transparent
holographic foil has a wider application range without wrinkles. It can be
hot-stamped on the inner LOGO and text, or hot-stamped before the four-color
printing, which can achieve a fantastic color flashing effect.
Special coating and cold foil matching
Some special coatings that can be printed
on the surface of shrink sleeves, including bright ink, matte ink, flexible
touch ink and UV casting ink, can be matched with hot stamping foil to achieve
complementary visual effects.
To achieve UV cast coating on the shrink
sleeve label, a UV coating with higher heat resistance is required. If you want
to achieve a soft surface effect, you can use a special style of UV matte
coating to make the color image and text on the shrink sleeve label The surface
forms a clear contrast. If you want to highlight the image, matte coating and
holographic UV cast coating can create a more realistic background color.
If you want to form a relief pattern, you
can use a specially formulated UV coating, which can print a texture effect on
the shrink sleeve label. The reason why the embossing effect is printed with
touchable ink is because the real embossment (relief formed by embossing) will
disappear during the label shrinking process. Using an anilox roller with a
large cell volume (25～90bcm), or
using rotary screen printing, can realize the relief effect or texture effect
that customers can really see, touch and feel on the shrink sleeve. Of course,
this coating must be an ink with thermal shrinkage properties. Special
surfactants and modified polyurethanes are used in high-viscosity UV coatings,
which have excellent flexibility, fluidity and good adhesion. It can be adapted
to various plastic films, such as PET, PETG and PVC.
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