HOW IT WORKS – Masterbatch

LCR Hallcrest produce and supply a range of additive Masterbatches usually in pellet form, for addition into many polymers.

We can also supply in free flow powder and liquid forms on request, suitable for injection moulding, blow moulding and extrusion. We can supply fully compounded product on request.

These specialist Masterbatches include:

THERMOCHROMIC – changing colour with changes in temperature

PHOTOCHROMIC – changing colour when exposed to uv light/sunlight

GLOW in the Dark – glowing in the dark after exposure to UV light and sunlight

These are reversible masterbatches, which change back to their original colour when the conditions are reversed.  The colour change can then be repeated time and again.

We have also created a special  ‘Irreversible’ Thermochromic type, where the colourchange can be ‘locked in’ under certain temperature conditions.

Let-down % or addition rates will depend on the strength of colour required and on the thickness of the plastic product being made.

These masterbatches are semi opaque colours, therefore the strength of colour builds up as the plastic thickness increases.

Thermochromic Masterbatch

The thermochromic materials are mixed and micro-encapsulated in our labs, then dried and milled, and added into a carrier resin which is extruded, cooled and then chipped or cut into small granule pellets approximately 2mm long.

We usually use eva and universal carriers.

Let down addition rates are normally between 3% and 6% depending on the colour strength required; or higher dosing for thinner products (sub 1mm thick) such as extruded drinking straws.

The best colours are achieved by using the clearest raw base polymers.

We produce masterbatches with activation temperatures (the point where the colour changes) from -15C up to +70C.

The colour change is not sudden but occurs over several degrees.

Thermochromic masterbatch is always a darker colour when colder, and a lighter colour when hotter.

Temperatures should always be kept to below 220C, in all parts including during heating through the barrel. At higher temperatures or if left dwelling at high temperature, the thermochromic can discolour, burn or lose its colour changing properties.

Thermochromic masterbatches are compatible in polypropalene, polystyrene, HIPS, EVA, HDPE, ABS, PU, TPE, TPU, PVC.

Available as either Single Colour, or Colour to Colour.  (We do also make triple colour masterbatches on request).

Single Colour: This is coloured when the temperature drops below the masterbatch’s activation temperature, and semi white when warmed above this temperature.  We supply a range of colours, such as white to blue, white to green, white to red.

Colour to Colour: This is a darker colour when the temperature drops below the masterbatch’s activation temperature, and a paler colour when warmed above this temperature. We supply a range of colours, for instance when heated: purple to pink, orange to yellow, green to yellow.

Triple colour:  This becomes lighter colours when heated, or darker colours when cooled, for instance yellow to orange to red.  Or white to pink to purple.

Photochromic Masterbatch

Available in a range of colours.

These are semi clear when unactivated indoors or out of direct uv light.  And become coloured when activated by uv light or sunlight.

E.g.  Clear to Purple, or Clear to Red.

The best colours are achieved by using the clearest raw base polymer.

Let down addition rates are normally between 3% and 6% depending on the colour strength required; or higher dosing for thinner products (sub 1mm thick) such as extruded drinking straws.

Glow in the Dark

Our high intensity Glow has a yellowy green glow when activated by exposure to UV light or sunlight.

The best colours are achieved by using the clearest raw base polymer.

Increasing plastic thickness will create a stronger and longer lasting glow.

Let down addition rates are normally above 5% depending on the colour strength required; or higher dosing for thinner products.

Injection moulding

This consists of high pressure injection of the raw polymer material using a ram or screw-type plunger to force/inject molten plastic material into a mould cavity, which then solidifies into a shape created by the cavity inside the mould.

When thermoplastics are moulded, typically pelletised raw material, including our colour-changing masterbatch, is fed through a hopper into a heated barrel with a reciprocating screw. Once in the barrel, the temperature increases and the screw mixes and delivers the raw material forward.  A volume known as a shot passes through a check valve and  into the mould cavity, to form the moulded item.

Two shot moulding can also be used with thermochromic masterbatch. This type of injection moulding can be used to add a soft touch to a product, or to produce an item with extra performance characteristics. An example is moulding a softer TPE, with a thermochromic additive in it, around the harder PP bowl of a baby’s feeding spoon.

Insert moulding.  Pre-moulded components can be inserted into the cavity while the mould is open, allowing the material injected in the next cycle to form and solidify around them. This process can be used to create plastic parts with an added colour changing property on the outside in a softer polymer such as TPE, eg baby feeding spoons.  It can also be used for In-mould labelling, where the IML has been first printed with thermochromic ink. eg as used in moulded plastic containers with an IML that changes colour when chilled.

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