In the plastic industry, different carriers for pigments and additives are used, and in that connection the terms"monocomponents"and"masterbatch"are used where a monocomponent in granulate form only contains one type of pigments or one additive, whereas a masterbatch, also in granulate form, may contain several monocomponents, i. e. several pigments and/or several additives. The most common carriers are PE, EVA or EMMA based waxes which allow a pigment concentration of about 50% at the most, though higher for black and white pigments.

Until now, masterbatch has been produced according to two methods, namely: A) As a product of different monocomponents mixed with a polymer carrier.

B) Several pigments directly mixed with a polymer carrier.

By method B, a greater pigment concentration has been achieved than by method A.

The object of the invention is to indicate a method of the kind mentioned in the intro- duction which enables attaining a hitherto unknown high pigment concentration in monocomponents as well as in masterbatch, in practice resulting in very significant economic advantages as well as advantages in use.

The method according to the invention is peculiar in that a low viscosity polymer car- rier in the shape of polybutylene (C4) or polypentene (Cs) is mixed with one or more pigments and/or one or more additives, possibly together with an auxiliary carrier, and is concentrated up to a pigment/additive content of 75-90 %, and that the mixture is melted and processed to become a granulate.

By using polybutylene (C4) or polypentene (Cs) as carrier, possibly in combination with one or more auxiliary wetting agents, it becomes possible to concentrate the pig-

ment content considerably and at the same time to achieve a melt that can be made a granulate. The final degree of concentration depends on the"oil number"of each pig- ment (need for wetting agent).

Preliminary tests have indicated that by using inorganic pigments, a pigment concen- tration above 90% may be attained, and that by using organic pigments, a pigment concentration over 75% may be attained. On this background it may be expected that by the method according to the invention there may be achieved still higher pigment concentrations. By extremely high pigment concentrations it seems advantageous to use an auxiliary wetting agent so that an even better humidification may be achieved than possible with polybutylene (C4) or polypentene (C5) as carrier medium as the pigment concentration may be increased hereby because a part of the carrier medium may be released for primarily constituting a binder.

The advantage of concentrating the pigment content is that there is e. g. room for addi- tives in a masterbatch whether this is produced directly or produced from monocom- ponents by the method according to the invention. Furthermore, a minimizing of the wax content in the masterbatch is achieved so that some of the negative effects by high wax concentration, e. g."nozzle sauce"and deposits, may be avoided.

By the method according to the invention, a recommended dosage of 1-2% is expected by a combination masterbatch compared with one of the leading producers in the word in this area recommending a dosage of about 6 %.

Preferably, by the method according to the invention there is used polybutylene (C4) or polypentene (Cs) as polymer carrier.

It may be particularly suitable if the melting of the mixture occurs by extrusion, pref- erably by means of a double screw extruder having great capacity compared to invest- ment in equipment.

By the method according to the invention it may be advantageous that a low viscosity wax, e. g. an oxidised polyethylene wax, is used as auxiliary carrier or wetting agent.

With the purpose of providing the finished plastic mass with specific material proper- ties, by the method according to the invention it may be possible to use a filler with a high melting point, e. g. calcium carbonate (chalk) or glass (Wollastonite), i. e. a filler which is not dissolved in the melt by the extrusion but makes cheaper or imparts higher pressure strength, respectively, to the material.

With the object of providing further specific material properties to the finished plastic mass, by the method according to the invention it may be possible that, besides a polymer carrier, fluid additives or additives with low melting point, e. g. Dynasylan Ameo or Chimasorb 81 (W absorber), may be applied, i. e. additives that are dis- solved in the melt by the extrusion.

Other specific material properties may be provided in masterbatches by further modi- fication by the method according to the invention so that, besides a polymer carrier, additives with low melting point, e. g. Chimasorb 81 (UV-absorber) or Dehydat 8312 (antistatic), may be applied, i. e. additives which are dissolved in the melt by the ex- trusion.

The method according to the invention may be further modified by the making of a combined masterbatch, e. g. for dyeing a TPU (thermo polyurethane), besides a poly- mer carrier there are used additives in the form of a laser contrast agent (e. g. Iriodin 25) and a release agent (e. g. Abrilube 77).

A further modification of the method according to the invention may consist in that for making a combined masterbatch, besides a polymer carrier there are used a UV- absorber (e. g. Chimasorb 81), an antistatic agent (e. g. Dehydat 831) and a flame retar- dant (e. g. Apymag AOH 850), i. e. the finished plastic mass is supplied with additives with specific material properties besides colour pigment.

The invention is now explained in more detail with reference to the examples below:

Example la (organic pigment) 10% polymer carrier polybutylene (C4) or polypentene (5), e. g. Vestowax B 912, 85% CI (colour index) pigment red 48: 1 and 5% auxiliary wetting agent, e. g. an oxi- dised polyethylene wax (Vestowax C 60) are mixed, melted and made to granulate.

Example Ib (organic pigment) 8% polymer carrier polybutylene (C4) or polypentene (Cs), e. g. Vestowax B 912,90% CI pigment green 7 and 2% auxiliary wetting agent, e. g. an oxidised polyethylene wax (Vestowax C 60) are mixed, melted and made to granulate.

Example Ic (organic pigment) 10% polymer carrier polybutylene (C4) or polypentene (Cs), e. g. Vestowax B 912, 80% Cl pigment black 7 and 10% auxiliary wetting agent, e. g. an oxidised polyethyl- ene wax (Vestowax C 60) are mixed, melted and made to granulate.

Example 2a (inorganic pigment) 10% polymer carrier polybutylene (C4) or polypentene (5), e. g. Vestowax B 912, 90% CI pigment yellow 184 are mixed, extruded and made to granulate.

Example 2b (inorganic pigment) 10% polymer carrier polybutylene (C4) or polypentene (Cs), e. g. Vestowax B 912, 90% CI pigment red 101 are mixed, extruded and made to granulate.

Example 3a (fillers) 10% polymer carrier polybutylene (C4) or polypentene (Cs), e. g. Vestowax B 912, 90% calcium carbonate or chalk are mixed, melted and made to granulate.

Example 3b (fillers) 10% polymer carrier polybutylene (C4) or polypentene (5), e. g. Vestowax B 912, and 90% crushed glass, e. g. Wollastonite, are mixed, melted and made to granulate.

Example 4a (fluid additives) 10% polymer carrier polybutylene (C4) or polypentene (CS), e. g. Vestowax B 912, 45% Dynasylan Ameo (fluid) and 45 % Aerosil (porosity) or other blown silicon are mixed, melted and made to granulate.

Example 4b (additives with low melting point) 10% polymer carrier polybutylene (C4) or polypentene (C5), e. g. Vestowax B 912, 70% Chimasorb 81 (UV-absorber) and 20% Aerosil (porosity) are mixed, melted and made to granulate.

Example 4c (additives with low melting point) 20% polymer carrier polybutylene (C4) or polypentene (Cs), e. g. Vestowax B 912, 80% Dehydat 8312 (antistatic) are mixed, melted and made to granulate.

Example 5a (combined masterbatch) 10% polymer carrier polybutylene (C4) or polypentene (5), e. g. Vestowax B 912,6% CI pigment yellow 184,54% titanium dioxide kronos 2230,20% Abrilube 77 (release agent) and 10% Iriodin 825 (laser contrast agent) are mixed, melted and made to granulate.

Example 5b (combined masterbatch) 9% polymer carrier polybutylene (C4) or polypentene (5), e. g. Vestowax B 912,15% Chimasorb 81 (LTV absorber), 25% Abrilube 77 (release agent), and 51% titanium dioxide kronos 2230 are mixed, melted and made to granulate.

Example 5c (combined masterbatch) 11% polymer carrier polybutylene (C4) or polypentene (Cs), e. g. Vestowax B 912, 1,5% Chimasorb 81 (UV absorber), 5% Dehydat 8312 (antistatic) and 82,5% Apymag AOH 850 (flame retardant) are mixed, melted and made to granulate.

By production experiments it has appeared that by using the indicated low viscosity polymer carrier, possibly together with an auxiliary carrier with even lesser viscosity, a pigment concentration above 90%, e. g. of the pigment iron oxide red, has been

achieved. The pigment was fully dispersed. The melt could be extruded and drawn into strings that could be cut to granulate after cooling. It is most possible that the product may also be produced by underwater granulating. Furthermore, it looks like the cutting may occur directly on the extruder head, i. e. only with air cooling, how- ever, something which is depending on optimal control of the tendency of the melt to stick-the blister material is not saturated yet.

The tests were made by means of a very short double screw extruder L/D 7. By using a more normal extruder L/D 40, the product will become even better.

It is to be noted that the indicated polymer carrier, besides its ability to wet the pig- ment optimally, is furthermore advantageous in that the melt with the pigment is so suited for being extruded, i. e. it is"coherent" (plastic) and workable at a suitable tem- perature and hard when cooled whereby it becomes possible to extrude it to granulate.

The high concentrations produced until now have been either a coating of pigment grains or powder compressed into granulate where only pressure made the product into the granulate form, which is not to favourable as the granulate cannot endure transport.

An important advantage by the new product made by the method according to the in- vention is the nature of the carrier together with the low concentration of it, implying that the product is more universally appliable that previous universal carriers, i. e. monocomponents or masterbatch made according to the invention are appliable in far more end materials than by products according to prior art.