The invention relates to a process for preparing a masterbatch, a masterbatch, and apparatus used for preparing a masterbatch.

Background to the Invention

Plastics have a wide use and there are many types of industries from liquid containers to fibres. Many of the products are used in the fast moving consumer industry and require colour for visual presentation. It is the masterbatch industry that supplies the colour additives to the plastic industry and the pigment is commonly suspended in a polymer. Masterbatch manufacturers use high speed mixers or internal mixers to first mix the pigment and this is then fed through an extruder with high temperatures and high pressures to combine the pigments and the carrier and to form a granule. The ideal properties of the pigment are for a high dispersion in the base material, common problems are that the pigment or other materials are subject to high temperatures as well as high pressures to combine them, as well as high sheet in the initial stages, this leads to degradation of the material as well as reagromalation of the pigment. Dispersion is therefore reduced due to the non-uniform particle size in the material i.e., a mix with a one micron particle size ends up with a percentage of higher micro particles, thus affecting the final distribution. The final colour, tint strength are affected by these various processes.

The inventor's previous patent ZA2010/00174, which is incorporated herein by reference, provides a masterbatch preparation process which includes: blending one or more of a molten wax and a non-wax polymer, and one or more liquid additives; l tempering the blend or cooling the blend to just above the congealing point thereof; solidifying the blend by cooling by dispensing the blend onto a cooled surface; and - comminuting said solidified blend. It has however been experienced that a masterbatch produced by this process blended with a Fisher Tropsch wax, being highly crystalline and or brittle, can breakup with ease which helps with dispersion and ease of processing in the production but can pose problems in transport and dosing of the finished product. It is important for some users that the particle size, shape and weight stay constant. The invention proposes novel ways of reducing or even eliminating the problem stated above in maintaining the shape, size and weight.

Summary of the Invention In the invention a masterbatch is used to colour plastics and add fillers and additives to plastics and the like. In one embodiment the carrier is a Fisher Tropsch wax. Fisher Tropsch wax is a low melting very low viscosity crystalline wax. The wax is the preferred carrier in the patent as it achieves high loading and dispersion of various chemicals fillers and pigments. The patent does cover various formula. Thus, according to the invention, there is provided a masterbatch with a composition of a wax and one or more of a pigment, a hardening agent, a binding agent, a coating agent, an additive, a filler, and a mineral oil. The filler may be a calcium carbonate or the like.

The chemical may be selected from a UV stabilizer, an antistatic agent, an antifogging agent, or another chemical used in the production of masterbatches or plastics. The wax may be a Fischer Tropsch wax.

The pigment and/or the filler and/or the chemical may be at least 10% up to 90% m/m. The mineral oil may be an agent that hardens, binds, coats and/or reduces brittleness in the said masterbatch, with a viscosity of the wax or higher in a molten or in its normal state being liquid, typically a silicon oil.

More specifically, the invention provides a masterbatch with a composition of:

- having at least 10% up to 90% m/m of a wax, typically a fisher Fischer Tropsch, a pigment and/or a filler and/or a chemical; and

- having from at least 3% and up to 90% m/m of a hardening agent, typically a low melt, high melt flow EVA ( ETHYLENE VINYL ACETATE).

The masterbatch composition may include a wax, more specifically a Fischer Tropsch wax; - at least 10% to 90% m/m of a pigment and/or a filler and/or a chemical; and

- a hardening agent, or polymer, or typically one or a combination of a polymer, copolymer, random copolymer, speciality polymer of at least 3% and up to 90% m/m of the composition.

The masterbatch composition may include a wax, more specifically a Fisher Tropsch Fischer Tropsch wax;

- at least 10% to 90% m/m of a pigment and/or a filler and/or a chemical; and

- a binding agent, typically a low melt, high melt flow elastomer of at least 3% and up to 90% m/m of the composition.

The masterbatch composition may include a wax, more specifically a Fisher Tropsch wax;

- at least 10% to 90% m/m of a pigment and/or a filler and/or a chemical; and

- a binding agent, typically a silicon oil, of at least 3% and up to 90% m/m of the composition. The masterbatch composition may include a wax, more specifically a Fisher Tropsch wax;

- at least 10% to 90% m/m of a pigment and/or a filler and/or a chemical; and

- a binding agent, typically latex, of at least 3% and up to 90% m/m of the composition.

The invention further provides a process of coating a masterbatch which includes one or more rollers having therein depressions or recesses wherein a masterbatch particle or pellet of a desired shape and size is formed.

In an embodiment there is at least 1 roller but more so 2 rollers, at least 1 of the said rollers having an impression where a shape may be formed, the said form would be of that which is common in the masterbatch industry.

To the 2 rollers a coating of material is applied, the said material can either be a liquid, molten form or hardened form. In the harden form it may be of a pre extruded film. In a molten or liquid form in a trough or heated pick-up trough or through a die from an extruder.

By rotating the 2 rollers it will pick up the coating and transfer or bring them together thereby enclosing the said masterbatch particle or pellet. This outer film will protect its enclosed particle or pellet.

The masterbatch may also be coated by way of spraying, or submerging in a bath and draining the said bath to leave a coating with any of the below materials in a suitable format i.e. molten or in solution or in a normal liquid state.

In this specification, unless the context clearly indicates the contrary, a "pigment" means a colouring material, Carbon Black or a Titanium Dioxide.

The invention will now be exemplified with non-limiting examples of masterbatch compositions and of an apparatus and a process for producing same. Examples of the Invention

The masterbatch compositions may have the following formulations, all percentages being on a m/m basis:

1. A first formulation being

* A Fisher Tropsch wax at 10% * An EVA at 10%

* A "Pigment" at 80%

2. A second formulation being

* A Fisher Tropsch wax at 10%

* An EVA at 5%

* A "Pigment" at 85%

3. Another formulation being

* A Fisher Tropsch wax at 20% * An EVA at 10%

* A "Pigment" at 70%

4. Another formulation being

* A Fisher Tropsch wax at 10% * An Elastomer at 10%

* A "Pigment" at 80% n being

^* A Fisher Tropsch wax at 10%

^* A silicon at 10%

^* A "Pigment" at 80% n being

^* A Fisher Tropsch wax at 17%

^* An EVA at 3%

^* A "Pigment" at 80% n being

^* A Fisher Tropsch wax at 17%

^* A polymer at 3%

^* A "Pigment" at 80% n being

^* A Fisher Tropsch wax at 47%

^* An EVA at 3%

^* A "Pigment" at 50% n being

* A Fisher Tropsch wax at 20%

^* A "Pigment" at 80%

^* A silicon coating ion being

* A Fisher Tropsch wax at 20%

^* A "Pigment" at 80%

* An EVA coating ion being

* A Fisher Tropsch wax at 20%

^* A "Pigment" at 80%

^* A poly coating ion being

* A Fisher Tropsch wax at 20%

^* A "Pigment" at 80%

* A pre extruded or formed film What follows is a non-limiting description of examples of apparatus and process of the Invention.

In Figure 1 is shown an example of an apparatus for carrying out the process of the invention, said apparatus including:

A - forming roller

B - pre formed film

C - Masterbatch compound

D - masterbatch enclosed

G - scraper

In Figure 2 is shown an example of an apparatus for carrying out the process of the invention, said apparatus including:

A - forming rollers

B - extrudate or molten material

C - masterbatch compound

D - enclosed/coated masterbatch

E - layer picked up or applied to forming rollers

F - heated tray/trough

G - scraper

In Figure 3 is shown an example of an apparatus for carrying out the process of the invention, said apparatus including:

A - forming rollers

B - pickup and transfer rollers

C - masterbatch compound

D - coated masterbatch

E - material transferred to roller (may be a liquid or cooled to form a film)

F - tray/trough may be heated

G - scraper The Figures that follow and their description above form an integral part of the body of the specification and are part of the description of the invention.