DE10063423A1 - Use of polyolefin wax synthesized with the aid of metallocene catalysts as a dispersant for pigments in a plastic matrix, e.g. for the production of pigment masterbatches - Google Patents

Abstract

The use of polyolefin wax (I) synthesized with the aid of metallocene catalysts as a dispersant for pigments in a plastic matrix. An Independent claim is also included for a method for the production of a masterbatch by mixing a polymer with a coloring agent in presence of (I).

Description

The present invention relates to a method for improved Production of a colorant consisting of at least one color donor, which is distributed very finely in a fusible base material (matrix), which at Room temperature is solid, as well as on the use of polyolefin waxes were made with the help of metallocene catalysts to improve the Dispersion of the colorant in a polyethylene matrix for the production of Polyethylene (LD) films.

Colorants such as pigment preparations are suitable for the production of masterbatches. A masterbatch is a granular, dust-free concentrate of a plastomeric or elastomeric plastic with a high proportion of a colorant. Masterbatches are used for coloring plastics, whereby the plastic to be colored before processing, e.g. B. in injection molding or before extrusion. The direct coloring of plastics with pure dyes before processing has proven technically disadvantageous because

• a) the distribution of the colorant and thus the color intensity achieved (Color strength) is insufficient, and
• b) the health risks caused by fine dust particles cannot be estimated, and
• c) the cost of cleaning the equipment after use of the dye or at Changes in the colorant are very high.

Various methods for producing masterbatches are known and described. The following processes are technically common in the production of masterbatches:

• a) the hot mixing of a suitable matrix (polymers such as PVC or ethylene Vinyl acetate, also LDPE) with the colorant
• b) extrusion and kneading with subsequent grinding of the color concentrate, or
• c) extrusion and subsequent fine spraying or hot cutting on the Perforated plate.

Below is an overview of the current state of the art Production of dust-free, powder or granular dye or Given pigment concentrates.

WO-93/10192 describes the production of fluorescent pigment concentrates using the pigment, a polymer that is either a polyester Melamine-formaldehyde resin or a triazine-formaldehyde resin can be one Fluorescent dye and a copolymer of ethylene and carbon monoxide as Dispersing agents. A mixture specified as the basic recipe contains here 0 to 46% polyethylene, 35% fluorescent pigment, 10% filler, 2% titanium dioxide, 2% Silcron® G-100 and 5 to 51% of the waxy dispersant, one Copolymers of carbon monoxide and ethylene. These waxy ones Dispersing aids are polar due to their carbon monoxide content Functionality that facilitates the wetting of the pigment, this functionality is but disadvantageous if you consider the thermal stability of the emerging Considered pigment concentrate. Pigment concentrates are in their manufacture and in the subsequent processing, especially with multiple extrusion high Exposed to thermal stress, d. H. an increasing intrinsic color of the Dispersing aid under this temperature load is a technical one Disadvantage.

EP-A-0 705 875 describes a universal masterbatch for adding fillers and especially from pigments to polymers that consist of a maximum of 85% from one filler (e.g. carbon black, titanium dioxide or ultra-man blue) and consists of a maximum of 25% a viscosity adjustment aid, namely either ethylene-bis-stearylamide (EBS wax), polybutylene or hot melt acrylates and a third component,  which makes up the rest of the mixture, namely styrene-butadiene block copolymers. The mixture also contains either a processing aid Metal stearate or stearic acid, other organic stearates or a Fluoroelastomer, maximum 2% by weight in total. There is also an antioxidant in the Mixture included. The inorganic pigment content is 30 to 60%. The Mixtures are relatively complex, the mechanical criteria are the quality criteria Properties of the end products are attracted without such important details Processing properties, stickiness, migration or printability of the Final article. As is known, stearates, as well as EBS wax as an aid in the production of pigment concentrates because of their high Tendency to migrate among the above Temperature loads to be clearly desired left. Due to the large number of components, the proportion is also small Possible errors in manufacturing and further processing.

EP-A-0 902 045 describes a masterbatch composition that improves Coloring properties in thermoplastics results from a pigment-containing Masterbatch is used. The masterbatch composition described contains a polymer made with the help of metallocene contact Compatibility with the pigment whose dispersion should improve. For a Granulated color masterbatch, the pigment content is a maximum of 80% without to give a concrete example. The polymer content is a maximum of 20% Polymer produced with the help of a metallocene contact with a non-uniformity by Max. 3.5. In addition, the font also contains references to the addition of other aids such. B. antistatic agents, antiblock additives and plasticizers.

In the prior art, the process for the production of color concentrates not disclosed in a satisfactory manner because quality criteria such as color strength or filter value are ignored. It is therefore not clear how and in to what extent the better dispersion of pigments mentioned as an advantage affects such quality criteria.

The object underlying the present invention was therefore through suitable choice of components from the group of the following  Group of polyolefin waxes an improvement in the dispersion of Pigments, especially organic pigments, in polyethylene as a matrix for To achieve production of foils.

Surprisingly, it has now been found that by metallocene catalysis waxes obtained a very good dispersion of pigments in polymers effect, and are therefore well suited for the production of masterbatches.

The invention therefore relates to the use of means Metallocene catalysts synthesized polyolefin waxes as dispersants for pigments in a plastic matrix.

Another object of the invention is a method for producing a Masterbatches by mixing a polymer with a colorant, characterized by the admixture of at least one by metallocene catalysis obtained polyolefin wax.

Homopolymers of ethylene or come as polyolefin waxes Copolymers of ethylene with one or more olefins in question. As Linear or branched olefins having 3-18 C atoms, preferably, are olefins 3-6 carbon atoms. Examples include propene, 1-butene, 1-hexene, 1-octene or 1-octadecene, still styrene. Copolymers of ethylene are preferred Propene or 1-butene. The copolymers consist of 70 to 99.9, preferably too 80 to 99% by weight of ethylene.

Polyolefin waxes with a dropping point between 90 and 130 ° C., preferably between 100 and 120 ° C., a melt viscosity at 140 ° C. between 10 and 10,000 mPa.s, preferably between 50 and 5000 mPa.s and a density at 20 are particularly suitable ° C between 0.89 and 0.98 g / cm ³ , preferably between 0.91 and 0.94 g / cm ³ .

The waxes can be used both as such and in polar modified form be used. Known possibilities for modification are  for example oxidation with air or graft polymerization with polar ones Monomers, for example maleic anhydride.

In preferred embodiments of the invention, the metallocene waxes used according to the invention are used in a mixture with auxiliaries and additives which improve the dispersing action of the metallocene waxes. Such auxiliaries and additives include, for example

• a) polyethylene glycol
• b) PE waxing,
• c) PTFE waxing,
• d) PP waxing,
• e) amide waxes,
• f) FT paraffins,
• g) montan growing,
• h) natural waxing,
• i) macro- and microcrystalline paraffins,
• j) polar polyolefin waxes, or
• k) Sorbitan esters
• l) polyamides
• m) polyolefins
• n) PTFE
• o) wetting agent
• p) silicates

Additive a) is polyethylene glycol, molecular weight range preferably 10 to 50,000 daltons, especially 20 to 35,000 daltons. The Polyethylene glycol is used in amounts of preferably up to 5% by weight admixed metallocene wax composition.

In preferred embodiments, additive b) is Polyethylene homo- and copolymer waxes, which are not by means of metallocene catalysis  were produced, and which have a number average molecular weight of 700 to 10,000 g / mol at a dropping point between 80 and 140 ° C.

In preferred embodiments, additive c) is Polytetrafluoroethylene with a molecular weight between 30,000 and 2,000,000 g / mol, in particular between 100,000 and 1,000,000 g / mol.

In preferred embodiments, additive d) is Polypropylene homo- and copolymer waxes, not by means of metallocene catalysis were produced, and which have a number average molecular weight of 700 to 10,000 g / mol at a dropping point between 80 and 160 ° C.

In preferred embodiments, additive e) is Amide waxes, producible by reacting ammonia or ethylenediamine with saturated and / or unsaturated fatty acids. The fatty acids are for example, stearic acid, tallow fatty acid, palmitic acid or erucic acid.

In preferred embodiments, additive f) is FT- Paraffins with a number average molecular weight of 400 to 800 g / mol a dropping point of 80 to 125 ° C.

Additive g) is preferably montan waxes including acid and ester waxes with a carbon chain length of the carboxylic acid from C ₂₂ to C ₃₆ . The ester waxes are preferably reaction products of montanic acids with mono- or polyhydric alcohols having 2 to 6 carbon atoms, such as, for example, ethanediol, butane-1,3-diol or propane-1,2,3-triol.

In a preferred embodiment, additive h) is Carnauba wax or candelilla wax.

Additive i) is paraffins and microcrystalline waxes, which incurred in oil refining. The dropping points of such paraffins are located  preferably between 45 and 65 ° C, that of such microcrystalline waxes preferably between 73 and 100 ° C.

In preferred embodiments, additive j) is polar polyolefin waxes, which can be prepared by oxidation of ethylene or propylene homopolymer and copolymer waxes or their grafting with maleic anhydride. Polyolefin waxes with a dropping point between 90 and 165 ° C., in particular between 100 and 160 ° C., a melt viscosity at 140 ° C. (polyethylene waxes) or at 170 ° C. (polypropylene waxes) between 10 and 10,000 mPas, in particular between, are particularly preferred for this purpose 50 and 5000 mPas and a density at 20 ° C between 0.85 and 0.96 g / cm ³ .

In preferred embodiments, additive k) is Reaction products of sorbitol (sorbitol) with saturated and / or unsaturated Fatty acids and / or montanic acids. The fatty acids are Examples include stearic acid, tallow fatty acid, palmitic acid or erucic acid.

Additive l) is preferably ground polyamide, for example polyamide-6, polyamide-6,6 or polyamide-12. The particle size of the Polyamides are preferably in the range of 5-200 microns, especially 10-100 microns.

Additive m) is a polyolefin, for example polypropylene, Polyethylene or copolymers of high or low density propylene and ethylene with molecular weights of preferably 10,000 to 1,000,000 D, in particular 15,000 to 500,000 D as the number average for the molecular weight, the particle size of Grinding is in the range of preferably 5-200 microns, in particular 10-100 microns.

Additive n) is thermoplastic PTFE with a molecular weight of preferably 500,000-10,000,000 D, in particular 500,000-2,000,000 D as a number average, the particle size of which in the range of preferably 5-200 microns, in particular 10-100 microns.  

Additive o) is an amphiphilic compound which in Generally lower the surface tension of liquids. Both Wetting agents are, for example, alkyl ethoxylates, fatty alcohol ethoxolates, Alkylbenzenesulfonates or betaines.

Additive p) is a silicate, which is not a filler or Pigment can be used in the recipes. Silicic acids or are preferred Talcum used.

The mixing ratio of component a) to components b) to p) can be in Range can be varied from 1 to 99 wt .-% a) to 1 to 99 wt .-% b) to p). Becomes If a mixture of several of the components b) to p) is used, then the Quantity specification for the sum of the quantities of these components.

In a preferred embodiment, the waxes are used in micronized form for the purpose according to the invention. The use of polyolefin wax and optionally admixed auxiliaries and additives as ultra-fine powder with a particle size distribution d ₉₀ <40 μm is particularly preferred.

The use of polyolefin waxes according to the invention is particularly preferred for the production of color concentrates for polypropylene fibers.

Metallocene catalysts for the preparation of the polyolefin waxes are chiral or nonchiral transition metal compounds of the formula M ¹ L _x . The transition metal compound M ¹ L _x contains at least one metal central atom M ¹ to which at least one Π ligand, e.g. B. a cyclopentadienyl ligand is bound. In addition, substituents such. B. halogen, alkyl, alkoxy or aryl groups to the metal central atom M ¹ . M ¹ is preferably an element of III., IV., V. or VI. Main group of the periodic table of the elements, such as Ti, Zr or Hf. Cyclopentadienyl ligand is understood to mean unsubstituted cyclopentadienyl radicals and substituted cyclopentadienyl radicals such as methylcyclopentadienyl, indenyl, 2-methylindenyl, 2-methyl-4-phenylindenyl, tetrahydroindenyl or octa-tetra-hydrofluoryl or octa-tetra-hydrofluoryl or octa. The Π ligands can be bridged or unbridged, whereby single and multiple bridging - also via ring systems - are possible. The term metallocene also includes compounds with more than one metallocene fragment, so-called multinuclear metallocenes. These can have any substitution pattern and bridging variant. The individual metallocene fragments of such multinuclear metallocenes can be of the same type or different from one another. Examples of such multinuclear metallocenes are e.g. B. described in EP-A-632 063.

Examples of general structural formulas of metallocenes and for their Activation with a cocatalyst are u. a. given in EP-A-571 882.

Examples

The melt viscosities of the waxes used below were determined using a rotary viscometer in accordance with DGF-M-III 8 (57), the dropping points in accordance with DGF-M-III 3 (75) (standards of the German Society for Fat Science), and the densities in accordance with DIN 53479. The filter value, which is defined as follows, is used to define the quality of the dispersion of a pigment in the polyolefin matrix:

D _F = (p _max - p ₀ ) / m _pigment

The filter value according to this definition therefore gives the extent of the pressure increase by filtration of a certain amount of dispersed pigment, again the degree of "blockage" of the filter by undispersed or poor dispersed pigment, based on the amount of pigment used.

In the production of the pigment masterbatches according to the example, a Henschel mixer FM 10 used, which is typically 4 to 10 minutes (at Room temperature) with 600 to 1500 revolutions / min for a statistical Distribution of the insert components ensures. The actual dispersion (typically one in an iPP matrix) takes place in a concurrent Twin-screw extruders with a process part length of 30 to 48 D instead of the  a temperature profile of 30 to 230 ° C (feed → nozzle) works. The Number of revolutions is between 100 to 550 revolutions / minute, it is with a throughput of 4 to 30 kg / h worked.

The following table shows the examples using the procedure according to the invention or comparative examples according to the prior art:

Claims (7)

1. Use of synthesized by means of metallocene catalysts Polyolefin waxes as dispersing agents for pigments in a plastic matrix. 2. Use according to claim 1, wherein the polyolefin wax from olefins with 3 to 6 carbon atoms or derived from styrene. 3. Use according to claim 1 and / or 2, wherein the polyolefin wax has a dropping point of 90 to 130 ° C, a melt viscosity at 140 ° C of 10 to 10000 mPa.s and a density of 0.89 to 0.98 g / cm ³ has. 4. Use according to one or more of claims 1 to 3, wherein the Polyolefin waxes are polar modified. 5. Use according to one or more of claims 1 to 4, wherein the polyolefin waxes in admixture with one or more auxiliaries and additives, selected from the group consisting of

• a) polyethylene glycol
• b) PE waxes,
• c) PTFE waxes,
• d) PP waxes,
• e) amide waxes,
• f) FT paraffins,
• g) Montan waxes,
• h) natural waxes,
• i) macro- and microcrystalline paraffins,
• j) polar polyolefin waxes,
• k) sorbitan esters,
• l) polyamides,
• m) polyolefins,
• n) PTFE,

in a weight ratio of polyolefin wax: auxiliary and additive 1:99 to 99: 1. 6. Use according to one or more of claims 1 to 5, wherein polyolefin wax and optionally the admixed auxiliaries and additives are present as ultra-fine powder with a particle size distribution d ₉₀ <40 µm. 7. Process for producing a masterbatch by mixing one Polymers with a colorant, characterized by the admixture at least a polyolefin wax obtained by metallocene catalysis.