Patent Application
20100093906
The present invention relates to active substance compositions comprising light stabilizers, especially UV stabilizers, and waxes and also to their preparation and use.
UV stabilizers comprehend a very wide variety of product classes such as, for example, UV absorbers, HALS products (hindered amine light stabilizers) or else quenchers.
The active substance compositions of the invention comprise waxes which have been prepared by means of metallocene catalysts, and which have a low dropping point, a high transparency, and low viscosity. As a result of the use of these waxes, the incorporation of UV stabilizers is facilitated; the operating temperatures can be kept significantly lower, and so a significantly higher loading than has hitherto been customary is possible, and there is no need for a polymeric carrier.
JP 2005054019 describes the production of exterior automotive components which comprise UV absorbers and HALS in fractions of up to 15 parts, and also up to 5 parts of antioxidants.
CN 1174855 discloses the production of a polyolefin masterbatch which comprises light sensitizers, light stabilization, antioxidants, and starch.
CN 1109479 describes the production of an aging inhibitor masterbatch based on polyolefin, which is admixed with process assistants at up to 2.5% by weight, up to 5% to 20% by weight of sebacates, and 1% to 10% by weight of tris-phosphites.
In the applications cited, additives, UV absorbers, and HALS products are added only up to about 25% by weight; higher added quantities are not found in the literature.
One possible way of increasing the added quantities would be, with a high-porosity raw material of costly and inconvenient preparation, to incorporate liquid or low-melting light stabilizers by stirring, and to draw them into the product with the aid of reduced pressure. This very special operation entails significantly higher costs and is limited in its applicability.
UV masterbatches produced by customary methods customarily contain not more than 10% by weight of UV or HALS products. Higher added quantities may, as a result of the difference in viscosity, lead to incorporation problems, to an uneven distribution of the components, and to reduced mechanical properties, such as lower strand strength in the masterbatches produced, for example.
One possible way of increasing the amount of active substance in the masterbatch would be to use special low-viscosity polymers, which accordingly have good processing properties at lower temperatures and allow the incorporation of a greater quantity of additive. Technical polymers which exhibit this profile of properties are usually classed in the high-price segment.
It was an object of the present invention to prepare active substance compositions with a very high fraction of UV stabilizers, in order to bring about, advantageously, the production of plastic-material components with high thermal stability, low discoloration tendencies, and good long-term behavior, technically, economically, and environmentally, and so to produce products of high quality. Furthermore, such compositions can be incorporated into a relatively large diversity of polymers with different chemical compositions, since there are fewer compatibility problems, as a result of the smaller amount of carrier material (the wax). The wax component, moreover, allows easier incorporation and distribution of the active substance composition in the polymers.
Among the waxes a distinction is made between essentially two groups: waxes prepared using metallocene catalysts (metallocene waxes), and those prepared in another way, such as by a molecular enlargement reaction using other catalysts, for example, or else those prepared, for example, by degradation reactions of polymers.
Surprisingly it has now been found that polyolefin waxes, especially polypropylene waxes, prepared using metallocene catalysts have especially advantageous suitability as carriers for UV stabilizers, allowing significantly higher loadings than was hitherto customarily the case.
This object is achieved in accordance with the invention by incorporating the UV stabilizers into a metallocene wax or into a mixture of different metallocene waxes, optionally comprising one or more nonmetallocene waxes and/or polymers, the predominant fraction being composed of metallocene wax. These types of wax used in accordance with the invention have been prepared in the presence of metallocene catalysts.
The present invention accordingly provides a light-resistant active substance composition comprising
In addition to the metallocene polyolefin wax, the composition of the invention may preferably further comprise one or more metallocene copolymer waxes of propylene and 0.1% to 50% of ethylene and/or 0.1% to 50% of at least one branched or unbranched 1-alkene having 4 to 20 carbon atoms, with a dropping point (ring/ball) of between 80 and 170° C. The metallocene waxes used in accordance with the invention have a melt viscosity, measured at a temperature of 170° C., in the range from 40 to 80 000 mPa·s, preferably from 45 to 35 000 mPa·s, more preferably from 50 to 10 000 mPa·s.
The waxes and/or the homopolymers and/or copolymers of ethylene and/or of propylene of the components ii), iii) and iv) melt at a temperature in the range from 80 to 170° C.
The waxes prepared in the presence of metallocene as catalyst are largely or entirely amorphous and may additionally, if necessary, have been given a polar modification.
Suitable nonmetallocene polyolefin waxes are apolar but also polar, nonmetallocene waxes selected from oxidized and nonoxidized waxes, having a dropping point in the range from 90 to 130° C. and a viscosity of less than 30 000 mPa·s, preferably less than 15 000 mPa·s, at a temperature of 140° C.
Suitable nonmetallocene polyolefin waxes are homopolymers of ethylene or of higher 1-olefins having 3 to 10 carbon atoms, or their copolymers with one another. The polyolefin waxes preferably have a weight-average molar mass Mw, of between 1000 and 20 000 g/mol and a number-average molar mass Mn of between 500 and 15 000 g/mol.
Additionally it is possible for copolymers and/or homopolymers of ethylene and/or of propylene to be used advantageously as compatibilizers in the composition of the invention. Suitable copolymers of ethylene here, for example, are ethylene-methyl acrylate copolymers, ethylene-ethyl acrylate copolymers, ethylene-butyl acrylate copolymers or ethylene-vinyl acetate copolymers.
Ethylene-methyl acrylate copolymers are especially suitable as copolymers of propylene.
These products typically possess a softening point of less than 60° C., a melting temperature of less than 100° C., a comonomer fraction of 10% to 20%, and a melt index of 190° C. and 2.16 kg of 1 to 10 g/10 min. In the further course of the description they are referred to as “copolymers of ethylene or of propylene”.
Mixtures preferred in accordance with the invention contain 10% to 90% by weight of light stabilizers, preferably 15% to 85% by weight, in particular 25% to 85% by weight, and also 10% to 90% by weight, preferably 15% to 85% by weight, of a metallocene polyolefin wax. Additionally it is possible for further stabilizers, organic and/or inorganic pigments, adjuvants, fillers such as silicates, nanoclays, silicas, and zeolites to be present at between 0% to 30% by weight. A listing of suitable adjuvants is found, for example, in “Plastics Additives Handbook”, 5th edition (2000), Hanser-Verlag.
In one preferred embodiment the composition of the invention contains 10% to 90% by weight, preferably 15% to 85% by weight, of the metallocene polyolefin wax, 0% to 30% by weight, preferably 0.1% to 25% by weight, of one or more nonmetallocene waxes and/or homopolymers and/or copolymers of ethylene and/or of propylene, 10% to 90% by weight, preferably 15% to 85% by weight, of one or more UV stabilizers, and 0% to 30% by weight of further fillers, pigments or additives.
The metallocene polyolefin waxes used in accordance with the invention are prepared using metallocene compounds of the formula I.
This formula also encompasses compounds of the formula Ia,
of the formula Ib
and of the formula Ic
In the formulae I, Ia, and Ib, M1 is a metal from group IVb, Vb or VIb of the Periodic Table of the Elements, examples being titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, and tungsten, preferably titanium, zirconium, and hafnium.
R1 and R2 are alike or different and are a hydrogen atom, a C1-C10, preferably C1-C3 alkyl group, especially methyl, a C1-C10, preferably C1-C3 alkoxy group, a C6-C10, preferably C6-C8 aryl group, a C6-C10, preferably C6-C8 aryloxy group, a C2-C10, preferably C2-C4 alkenyl group, a C7-C40, preferably C7-C10 arylalkyl group, a C7-C40, preferably C7-C12 alkylaryl group, a C8-C40, preferably C8-C12 arylalkenyl group or a halogen atom, preferably chlorine atom.
R3 and R4 are alike or different and are a mono- or polycyclic hydrocarbon radical which is able to form a sandwich structure with the central atom M1. R3 and R4 are preferably cyclopentadienyl, indenyl, tetrahydroindenyl, benzoindenyl or fluorenyl, it being possible for the parent structures to carry additional substituents or to be bridged with one another. In addition it is possible for one of the radicals R3 and R4 to be a substituted nitrogen atom, in which case R24 has the definition of R17 and is preferably methyl, tert-butyl or cyclohexyl.
R5, R6, R7, R8, R9, and R10 are alike or different and are each a hydrogen atom, a halogen atom, preferably a fluorine, chlorine or bromine atom, a C1-C10, preferably C1-C4 alkyl group, a C6-C10, preferably C6-C8 aryl group, a C1-C10, preferably C1-C3 alkoxy group, a radical —NR162, —SR16, —OSiR163, —SiR163 or —PR162, in which R16 is a C1-C10, preferably C1-C3 alkyl group or C6-C10, preferably C6-C8 aryl group or else, in the case of radicals containing Si or P, is a halogen atom, preferably chlorine atom, or pairs of adjacent radicals R5, R6, R7, R8, R9 or R10 form a ring with the carbon atoms connecting them. Particularly preferred ligands are the substituted compounds of the parent structures cyclopentadienyl, indenyl, tetrahydroindenyl, benzoindenyl or fluorenyl.
R13 is
=BR17, =AlR17, —Ge—, —Sn—, —O—, —S—, ═SO, ═SO2, ═NR17, ═CO, ═PR17 or ═P(O)R17, where R17, R18, and R19 are alike or different and are each a hydrogen atom, a halogen atom, preferably a fluorine, chlorine or bromine atom, a C1-C30, preferably C1-C4 alkyl, especially methyl group, a C1-C10 fluoroalkyl, preferably CF3 group, a C6-C10 fluoroaryl, preferably pentafluorophenyl group, a C6-C10, preferably C6-C8 aryl group, a C1-C10, preferably C1-C4 alkoxy, especially methoxy group, a C2-C10, preferably C2-C4 alkenyl group, a C7-C40, preferably C7-C10 aralkyl group, a C8-C40, preferably C8-C12 arylalkenyl group or a C7-C40, preferably C7-C12 alkylaryl group, or R17 and R18 or R17 and R19 each form a ring together with the atoms connecting them.
M2 is silicon, germanium or tin, preferably silicon and germanium. R13 is preferably ═CR17R18, ═SiR17R18, ═GeR17R18, —O—, —S—, ═SO, —PR17 or ═P(O)R17.
R11 and R12 are alike or different and have the definitions stated for R17, m and n are alike or different and are zero, 1 or 2, preferably zero or 1, with m plus n being zero, 1 or 2, preferably zero or 1.
R14 and R15 have the definition of R17 and R18.
Examples of suitable metallocenes are as follows:
The single-center catalyst systems are activated using suitable cocatalysts. Suitable cocatalysts for metallocenes of the formula I are organoaluminum compounds, especially alumoxanes, or else aluminum-free systems such as R20xNH4-xBR214, R20xPH4-xBR214, R203CBR214 or BR213. In these formulae, x is a number from 1 to 4, the radicals R20 are alike or different, preferably alike, and are C1-C10 alkyl or C6-C18 aryl, or two radicals R20 form a ring together with the atom connecting them, and the radicals R21 are alike or different, preferably alike, and are C6-C18 aryl which may be substituted by alkyl, haloalkyl or fluorine. In particular R20 is ethyl, propyl, butyl or phenyl and R21 is phenyl, pentafluorophenyl, 3,5-bistrifluoromethylphenyl, mesityl, xylyl or tolyl.
Frequently a third component is necessary in addition in order to ensure protection against catalyst poisons. Suitability for this purpose is possessed by organoaluminum compounds such as, for example, triethylaluminum, tributylaluminum, and others, and also mixtures.
Depending on the process it is also possible for supported single-center catalysts to be used. Preference is given to catalyst systems in which residues of support material and cocatalyst do not exceed a concentration of 100 ppm in the product.
The melt viscosities here were determined to DIN 53019 using a rotary viscometer, the dropping points to DIN 51801/2, and the ring/ball softening points to DIN EN 1427. The dropping point is determined using an Ubbelohde dropping point instrument to DIN 51801/2, the ring/ball softening point to DIN EN 1427.
UV stabilizers which can be used are primarily three different classes of product: sterically hindered amines (HALS), nickel quenchers and/or UV absorbers. Also possible are combinations of different HALS, nickel quenchers or UV absorbers, and also mixtures of the products with one another. This relates to all of the products cited in “Plastics Additives Handbook”, 5th edition (2000), Hanser-Verlag pages 114-136.
UV stabilizers that can be used in accordance with the invention are specified in EP-B-981530 (page 5 line 7 to page 28 line 30). EP-A-981530 is hereby expressly incorporated by reference. Preference is given to compounds as described in EP-B-981530 at page 13 lines 22 to 26 and page 28 lines 28 to 30.
Quenchers which can be used in accordance with the invention are specified in EP-B-981530 at page 42 lines 50 to 55. Particular preference is given to the compound having the CAS number 14516-71-3 (trade name Cyasorb UV-1084).
The incorporation of the UV stabilizers into the waxes takes place in accordance with the known state of the art, by combining all of the components at an elevated temperature to form a homogeneous mass and then converting that mass into a suitable end-product form. Mixtures of this kind are normally produced in an extruder or compounder, although there are other assemblies used even less often. The end-product form usually comprises granules, which are produced by strand pelletizing, hot cutting or underwater pelletizing. Of the methods known, preference is given especially to the extruder and to underwater pelletizing.
The fraction of metallocene waxes required is dependent on the processing properties and also on the granule strengths of the intermediates, the specification of the properties of the completed material, its surface qualities, and its requisite optical properties.
Besides the waxes and light stabilizers, the compositions of the invention may of course also comprise other substances, such as further processing stabilizers and phenolic antioxidants, for example, to name but a few. Particularly noteworthy here are the phenolic, phosphitic and phosphonitic antioxidants, not forgetting the secondary antioxidants.
In the case of the phenolic antioxidants this relates in particular to tetrakis[methylene(3,5-di-tert-butyl-4-hydroxyhydrocinnamate)]methane, 1,2,3-tris(3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate, octadecyl 3,5-di-tert-butyl-4-hydroxyhydrocinnamate, bis[3,3-bis(4′-hydroxy-3′-tert-butylphenyl)butanoic acid) glycol ester, mixture of tetrakis[methylene(3,5-di-tert-butyl-4-hydroxyhydrocinnamate)]methane and bis[3,3-bis(4′-hydroxy-3′-tert-butylphenyl)butanoic acid) glycol ester or ethylenebis-(oxyethylene)bis-(3-(5-tert-butyl-4-hydroxy-m-tolyl) propionate.
In the case of the phosphite and phosphonite antioxidants, mention may be made here, in particular, of tris(2,4-di-tert-butylphenyl) phosphite, bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, and the CAS Reg. Nos 119345-01-6/38613-77-3.
In the case of the costabilizers, mention may be made here, in particular, of distearyl 3,3′-thiodipropionate and distearyl disulfide.
Further processing stabilizers and antioxidants which can be used in accordance with the invention are disclosed in EP-B-981530 (page 40 line 10 to page 42 line 17 and page 44 lines 45 to 55).
The present invention also provides a process for producing the active substance composition of the invention by combining the individual constituents and then homogenizing them in an extruder or compounder. The preliminary mixing of the individual components is preferred in the preparation of the composition and can take place in a suitable mixing apparatus; alternatively, if desired, further additives may not be added until later, via a side feed, in solid or liquid form.
The raw materials used may be present in any of a very wide variety of forms. The waxes, and also the further adjuvants and additives, may be present, for example, in the form of granules, flakes or powders, including ultrafine powders, in the mixture, while the light stabilizers may also, additionally, be present in liquid form.
For the production of dust-free, highly loaded active substance compositions in granular and powder forms, the following single-stage or multistage methods are presently known:
All of the components can be mixed cold, addition taking place via the main feed of an extruder, or the waxlike/polymeric fractions of the formulation are fed in via the main feed of the extruder, the powderous or liquid UV stabilizers being introduced into the machine via corresponding side feeds. Mixing in the melt can be carried out subsequently in a suitable extruder or in compounders. This is followed by pelletizing, grinding or spraying.
A cold mix is composed of suitable polymeric carriers, such as polyethylene, polypropylene or ethylene-vinyl acetate, for example. The disadvantage of such polymer mixtures is the often limited compatibility of individual components, in which case there may be separation of polymer and the adjuvants such as the light stabilizers.
In the case of mixing at an elevated temperature, the thermal energy may be introduced via friction, via separate heating of the mixing vessel, or in both ways.
Where the composition is produced in an extruder, it is preferred to operate with a screw structure matched to the high active substance content. The temperature profile is preferably lower than indicated in the state of the art. For producing the compositions of the invention it is advantageous to employ a strand pelletizing method, although underwater pelletizing or hot cutting can also be employed.
The compositions of the invention allow semisynthetic or synthetic polymers to be stabilized against the harmful influence of high-energy radiation such as light or UV, but also against heat, degradation by oxygen, or other degradation processes, and they are therefore used in particular for the production of UV-stable plastic materials or articles made of plastic material.
In contrast to the UV-stabilized compositions described in the prior art, the products according to the invention can be used to stabilize a broad selection of polymers. Examples include the following: polyolefins, ethylene-vinyl acetate copolymers (EVA), styrene-acrylonitrile copolymers (SAN), polyvinyl chloride (PVC), polyamide (PA), polyethylene glycol terephthalate (PET), polybutylene glycol terephthalate (PBT) and copolyesters thereof, acrylonitrile-butadiene-styrene copolymers (ABS), polycarbonate (PC), and also various specialty polymers. Also suitable, in addition, are all natural, semisynthetic or synthetic polymers, which includes coating materials as well.
After blending with the polymer and attainment of the required target concentration, the plastic-material mixtures can then be processed further to the desired end products.
The metallocene waxes a to d used in accordance with the invention, and listed in table 1, were prepared by copolymerizing propylene with ethylene using the metallocene catalyst dimethylsilylbisindenylzirconium dichloride in accordance with the process specified in EP A 0 384 264 (general instructions, examples 1-16). The different softening points and viscosities were set by varying the ethylene feed and the polymerization temperature.
The product characteristics are determined in accordance with the following methods:
The UV stabilizer composition of the invention was prepared as described below:
As the mixture for extrusion:
Mixer: Hentschel mixer, volume 5 liters
Batch: corresponding to the examples given below
Preliminary mixing: batching for about 2 to 4 min at rpm=600/min
The preliminary mixture is formed from the wax or wax/polymer mixtures; the addition of HALS and/or UV stabilizer was made via corresponding side feed equipment.
Extrusion took place subsequently on a co-rotating twin screw with downstream strand pelletizing or underwater pelletizing. Granule sizes 0.8 to 3 mm in diameter.
In the examples below, the following composition was prepared by the processes described above. The metallocene waxes used in each case comprised the wax described above.
The additive combinations according to preparation examples 1 to 19 were partly premixed and extruded in a co-rotating twin screw with a special screw structure and also with a low temperature profile. In different polymers this led to reduced color changes, higher thermal stabilities and increased stability toward UV light, and also to an improvement in quality.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2006 047 854.1 | Oct 2006 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2007/008591 | 10/4/2007 | WO | 00 | 4/8/2009 |
