Abstract:
The present invention relates to a method of using polyolefin waxes prepared by means of metallocene catalysts as additive components in printing inks and surface coatings.

Description:
The present invention relates to the use of polyolefin waxes, in particular of ethylene and propylene homopolymer and copolymer waxes, prepared using metallocene catalysts. 
     BACKGROUND OF THE INVENTION 
     Polyolefin waxes are important for many application areas. Their use as additives in printing inks and surface coatings is attracting increasing interest. In printing inks, waxes increase the wear, abrasion and scratch resistance of printed products. In surface coatings, waxes serve not only to improve the mechanical properties of the coating surface but also to achieve matting effects (cf. Ullmann&#39;s Encyclopedia of Industrial Chemistry, Weinheim, Basel, Cambridge, New York, 5.ed., Vol. A 28, p. 103 ff). For the printing ink and surface coatings applications, the waxes are used in the form of solvent dispersions or pastes or else in solid micronized form. Micronization is carried out either by milling in suitable mills or by spraying from the melt, in each case with subsequent classification if necessary. The required average particle sizes are generally below 10 μm. 
     For these applications, use has hitherto been made of waxes from various preparation processes. A customary method is, apart from free-radical polymerization at high pressures and temperatures, the preparation of waxes in solution using Ziegler-Natta catalysts comprising a titanium compound as catalytically active species (cf. DE-A-1 520 914, U.S. Pat. No. 3,951,935, U.S. Pat. No. 4,039,560, EP-A-584 586). 
     The nonuniformity of the products can be seen from a broad distribution of the chain lengths, i.e. the polydispersity, from the nonuniformity of the incorporation of comonomers within a chain and the distribution of the comonomer content between various types of chains. This leads to products having reduced hardness and containing volatile or extractable components. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to find improved polyolefin waxes as additives in surface coatings and printing inks. 
     This object is achieved by use of polyolefin waxes which are prepared by olefin polymerization using metallocene catalyst systems. 
     It has been found that, in particular, the use of metallocene catalyst systems in the preparation of polyolefin waxes leads to materials which give improved abrasion resistance or matting effects when used in printing inks and surface coatings. 
     Furthermore, it has been found that polyolefin waxes prepared using metallocenes are also, owing to the uniform structure within the polymer chain, advantageous compared to waxes likewise having a narrow distribution but prepared using Ziegler-Natta catalyst. 
     Possible processes for preparing the polyolefin waxes of the invention are described in EP-A-571 882 and EP-A-602 509. However, other processes such as solution, suspension, gas-phase or bulk processes which make it possible to use metallocene or other single-center catalyst systems based on titanium, nickel, palladium or vanadium compounds are also suitable in principle. 
     The object of the invention is achieved by polyolefins and polyolefin waxes which are prepared by means of metallocene catalysts and are used for producing printing inks, surface coatings, melt adhesives and photocopier toners. 
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Preference is given to polyolefin waxes prepared using sandwich chelate compounds, in particular those prepared using metallocene compounds, wherein the metallocene is a compound of the formula I: ##STR1## 
     This formula also encompasses compounds of the formula Ia ##STR2## the formula Ib ##STR3## and the formula Ic ##STR4## 
     In the formulae I, Ia, Ib and Ic, M 1  is a metal of group IVb, Vb or VIb of the Periodic Table, for example titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, preferably titanium, zirconium or hafnium. 
     R 1  and R 2  are identical or different and are each a hydrogen atom, a C 1  -C 10  --, preferably C 1  -C 3  -alkyl group, a C 1  -C 10  --, preferably C 1  -C 3  -alkoxy group, a C 6  -C 10  --, preferably C 6  -C 8  -aryl group, a C 6  -C 10  --, preferably C 6  -C 8  -aryloxy group, a C 2  -C 10  --, preferably C 2  -C 4  -alkenyl group, a C 7  -C 40  --, preferably C 7  -C 10  -arylalkyl group, a C 7  -C 40  --, preferably C 7  -C 12  -alkylaryl group, a C 8  -C 40  --, preferably C 8  -C 12  -arylalkenyl group or a halogen atom, preferably chlorine or methyl. 
     R 3  and R 4  are identical or different and are each a monocyclic or polycyclic hydrocarbon radical which can form a sandwich structure with the central atom M 1 . R 3  and R 4  are preferably cyclopentadienyl, indenyl, benzindenyl or fluorenyl, where the base structures can also bear additional substituents or be bridged to one another. Furthermore, one of the radicals R 3  and R 4  can be a substituted nitrogen atom, where R 24  is as defined for R 17  and is preferably methyl, t-butyl or cyclohexyl. 
     R 5 , R 6 , R 7 , R 8 , R 9  and R 10  are identical or different and are each a hydrogen atom, a halogen atom, preferably a fluorine, chlorine or bromine atom, a C 1  -C 10  --, preferably C 1  -C 4  -alkyl group, a C 6  -C 10  --, preferably C 6  -C 8  -aryl group, a C 1  -C 10  --, preferably C 1  -C 3  -alkoxy group, a --NR 16   2  --, --SR 16  --, --OSiR 16   3  --, --SiR 16   3  -- or --PR 16   2  radical, where R 16  is a C 1  -C 10  --, preferably C 1  -C 3  -alkyl group or C 6  -C 10  --, preferably C 6  -C 8  -aryl group or, in the case of Si-- or P-- containing radicals, a halogen atom, preferably a chlorine atom, or two adjacent radicals R 5 , R 6 , R 7 , R 8 , R 9  or R 10  together with the carbon atoms connecting them form a ring. Particularly preferred ligands are the substituted compounds of the base structures indenyl, benzindenyl, fluorenyl and cyclopentadienyl. 
     R 13  is ##STR5## ═BR 17 , ═AIR 17 , --Ge--, --Sn--, --O--, --S--, ═SO, ═SO 2 , ═NR 15 , ═CO, ═PR 15  or ═P(O)R 15  where R 17 , R 18  and R 19  are identical or different and are each a hydrogen atom, a halogen atom, a C 1  -C 30  --, preferably C 1  -C 4  -alkyl group, in particular a methyl group, a C 1  -C 10  -fluoroalkyl group, preferably a CF 3  group, a C 6  -C 10  -fluoroaryl group, preferably a pentafluorophenyl group, a C 6  -C 10  --, preferably C 6  -C 8  -aryl group, a C 1  -C 10  --, preferably C 1  -C 4  -alkoxy group, in particular a methoxy group, a C 2  -C 10  --, preferably C 2  -C 4  -alkenyl group, a C 7  -C 40  --, preferably C 7  -C 10  -arylalkyl group, a C 8  -C 40  --, preferably C 8  -C 12  -arylalkenyl group or a C 7  -C 40  --, preferably C 7  -C 12  -alkylaryl group, or R 17  and R 18  or R 17  and R 19  in each case together with the atoms connecting them form a ring. 
     M 2  is silicon, germanium or tin, preferably silicon or germanium. 
     R 13  is preferably ═CR 17  R 18 , ═SiR 17  R 18 , ═GeR 17  R 18 , --O--, --S--, ═SO, ═PR 17  or ═P(O)R 17 . 
     R 11  and R 12  are identical or different and are as defined for R 17 . m and n are identical or different and are zero, 1 or 2, preferably zero or 1, where m plus n is zero, 1 or 2, preferably zero or 1. 
     R 14  and R 15  are as defined for R 17  and R 18 . 
     Examples of suitable metallocenes are: 
     bis(1,2,3-trimethylcyclopentadienyl)zirconium dichloride, 
     bis(1,2,4-trimethylcyclopentadienyl)zirconium dichloride, 
     bis(1,2-dimethylcyclopentadienyl)zirconium dichloride, 
     bis(1,3-dimethylcyclopentadienyl)zirconium dichloride, 
     bis(1-methylindenyl)zirconium dichloride, 
     bis(1-n-butyl-3-methyl-cyclopentadienyl)zirconium dichloride, 
     bis(2-methyl-4,6-di-i-propylindenyl)zirconium dichloride, 
     bis(2-methylindenyl)zirconium dichloride, 
     bis(4-methylindenyl)zirconium dichloride, 
     bis(5-methylindenyl)zirconium dichloride, 
     bis(alkylcyclopentadienyl)zirconium dichloride, 
     bis(alkylindenyl)zirconium dichloride, 
     bis(cyclopentadienyl)zirconium dichloride, 
     bis(indenyl)zirconium dichloride, 
     bis(methylcyclopentadienyl)zirconium dichloride, 
     bis(n-butylcyclopentadienyl)zirconium dichloride, 
     bis(octadecylcyclopentadienyl)zirconium dichloride, 
     bis(pentamethylcyclopentadienyl)zirconium dichloride, 
     bis(trimethylsilylcyclopentadienyl)zirconium dichloride, 
     biscyclopentadienyidibenzylzirconium, 
     biscyclopentadienyidimethylzirconium, 
     bistetrahydroindenylzirconium dichloride, 
     dimethylsilyl-9-fluorenylcyclopentadienylzirconium dichloride, 
     dimethylsilylbis-1-(2,3,5-trimethylcyclopentadienyl)zirconium dichloride, 
     dimethylsilylbis-1-(2,4-dimethyl-cyclopentadienyl)zirconium dichloride, 
     dimethylsilylbis-1-(2-methyl-4,5-benzindenyl)zirconium dichloride, 
     dimethylsilylbis-1-(2-methyl-4-ethylindenyl)zirconium dichloride, 
     dimethylsilylbis-1-(2-methyl-4-i-propylindenyl)zirconium dichloride, 
     dimethylsilylbis-1-(2-methyl-4-phenylindenyl)zirconium dichloride, 
     dimethylsilylbis-1-(2-methylindenyl)zirconium dichloride, 
     dimethylsilylbis-1-(2-methyltetrahydroindenyl)zirconium dichloride, 
     dimethylsilylbis-1-indenylzirconium dichloride, 
     dimethylsilylbis-1-indenyldimethylzirconium, 
     dimethylsilylbis-1-tetrahydroindenylzirconium dichloride, 
     diphenylmethylene-9-fluorenylcyclopentadienylzirconium dichloride, 
     diphenylsilylbis-1-indenylzirconium dichloride, 
     ethylenebis-1-(2-methyl-4,5-benzoindenyl)zirconium dichloride, 
     ethylenebis-1-(2-methyl-4-phenylindenyl)zirconium dichloride, 
     ethylenebis-1-(2-methyltetrahydroindenyl)zirconium dichloride, 
     ethylenebis-1-(4,7-dimethylindenyl)zirconium dichloride, 
     ethylenebis-1-indenylzirconium dichloride, 
     ethylenebis-1-tetrahydroindenylzirconium dichloride, 
     indenylcyclopentadienylzirconium dichloride 
     isopropylidene(1-indenyl)(cyclopentadienyl)zirconium dichloride, 
     isopropylidene(9-fluorenyl)(cyclopentadienyl)zirconium dichloride, 
     phenylmethylsilylbis-1-(2-methylindenyl)zirconium dichloride, 
     and also the alkyl or aryl derivatives of each of these metallocene dichlorides. 
     To activate the single-center catalyst systems, suitable cocatalysts are used. Suitable cocatalysts for metallocenes of the formula I are organoaluminum compounds, in particular aluminoxanes, or aluminum-free systems such as R 22   x  NH 4-x  BR 23   4 , R 22   x  PH 4-x  BR 23   4 , R 22   3  CBR 23   4  or BR 23   3 . In these formulae, x is from 1 to 4, the radicals R 22  are identical or different, preferably identical, and are C 1  -C 10  -alkyl or C 6  -C 18  -aryl or two radicals R 22  together with the atom connecting them form a ring, and the radicals R 23  are identical or different, preferably identical, and are C 6  -C 18  -aryl which may be substituted by alkyl, haloalkyl or fluorine. In particular, R 22  is ethyl, propyl, butyl or phenyl and R 23  is phenyl, pentafluorophenyl, 3,5-bis(trifluoromethyl)-phenyl, mesityl, xylyl or tolyl. 
     These cocatalysts are particularly suitable in combination with metallocenes of the formula I, when R 1  and R 2  are each a C 1  -C 10  -alkyl group or an aryl or benzyl group, preferably a methyl group. Derivative formation to give the metallocenes of the formula I can be carried out by methods known from the literature, for example by reaction with alkylating agents such as methyllithium (cf. Organometallics 9 (1990) 1539; J. Am. Chem. Soc. 95 (1973) 6263). 
     In addition, a third component is frequently necessary to provide protection against polar catalyst poisons. Organoaluminum compounds such as triethylaluminum, tributylaluminum and others, as well as mixtures, are suitable for this purpose. 
     Depending on the process, supported single-center catalysts can also be used. Preference is given to catalyst systems in which the residual contents of support material and cocatalyst in the product do not exceed a concentration of 100 ppm. 
     To prepare the polyolefin waxes of the invention, homopolymerizations, copolymerizations or terpolymerizations of olefins or diolefins having from 2 to 18 carbon atoms are carried out. Examples of olefins which can be used are ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 2-methyl-1-propene, 3-methyl-1-butene, 3-methy-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, styrene or cyclic olefins such as cyclopentene, cyclohexene, norbornene, 1,4,5,8-dimethano-1,2,3,4,4a,5,8,8a-octahydronaphthalene and their structural derivatives and also diolefins such as 1,5-hexadiene, 1,7-octadiene, 1,3- or 1,5-cyclooctadiene. Preference is given to polymerizing ethylene or propylene and also to copolymerizing ethylene or propylene with an olefin having from 2 to 10 carbon atoms. Examples of copolymer waxes are ethylene-propylene, ethylene-1-butene, ethylene-1-hexene, ethylene-norbornene and propylene-ethylene, propylene-1-butene waxes. 
     Examples of terpolymers are ethylene-propylene-1-butene or ethylene-propylene-1,5-hexadiene terpolymer waxes. 
     Copolymer waxes contain from 0 to 20% by weight of the comonomer, based on the total polymer. Terpolymer waxes comprise at least 80% by weight of the main monomer, while the two comonomers are each present in an amount of up to 19% by weight but the sum of the amounts of the two comonomers does not exceed 20% by weight of the total monomer. 
     The polyolefin waxes described below are particularly suitable for the applications mentioned: 
     Polyethylene waxes prepared using metallocene compounds and having a narrow molecular weight distribution M w  /M n  &lt;5, preferably &lt;3, a melt viscosity of from 5 to 100000 mPas measured at 140° C. and a melting point of from 137° to 70° C. 
     Polypropylene waxes prepared using metallocene compounds and having a narrow molecular weight distribution M w  /M n  &lt;5, preferably &lt;3, a melt viscosity of from 5 to 100000 mPas measured at 170° C. and a melting point of from 165° to 70° C. 
     Definitions: 
     M w  =weight average molar mass in g/mol determined by GPC 
     M n  =number average molar mass in g/mol determined by GPC 
     M w  /M n  =polydispersity 
     GPC=gel permeation chromatography 
    
    
     EXAMPLE 1 
     To prepare the catalyst, 18 mg of bis(cyclopentadienyl)zirconium dichloride are dissolved in 10 cm 3  of 10% strength by weight methylaluminoxane solution in toluene and are preactivated by allowing to stand for 15 minutes. In parallel to this, a dry 16 dm 3  -vessel which has been flushed with nitrogen is charged with 4 kg of propane and, at 30° C., 1.0 bar of hydrogen and 4.5 bar of ethylene are metered in. The reactor is heated to 70° C. and stirred at 100 rpm. After 20 minutes, the polymerization is started at 250 rpm by addition of the catalyst via the pressure lock. The polymerization temperature is regulated at 70° C. by cooling and the composition in the gas space is kept constant by metering in more of the components. After a polymerization time of 1 hour, the reaction is stopped by addition of isopropanol and the reactor is vented and opened. Vacuum drying of the product gives 1.9 kg of polyethylene wax having a VN (viscosity number) of 16 cm 3  /g. DSC (Differential Scanning Calorimetry) indicates a melting point of 123° C. and a melting enthalpy of 254 [J/g]. Further property data are shown in Table 1. 
     EXAMPLE 2 
     To prepare the catalyst, 8 mg of rac-ethylene-bis-tetrahydroindenylzirconium dichloride in 5 cm 3  of 10% strength by weight methylaluminoxane solution in toluene are used. The reactor from Example 1 is charged with 1 kg of propane and 2.5 kg of propene and, at 30° C., 1.2 bar of hydrogen are metered in. Polymerization is carried out as in Example 1. Vacuum drying of the product gives 1.60 kg of polypropylene wax having a VN of 6.7 cm 3  /g. DSC indicates a melting point of 124° C. and a enthalpy of fusion of 92 [J/g]. Further property data are shown in Table 1. 
     EXAMPLE 3 
     To prepare the catalyst, 27 mg of bis-n-butylcyclopentadienylzirconium dichloride in 5 cm 3  of 10% strength by weight methylaluminoxane solution in toluene are used. The reactor from Example 1 is charged with 3 kg of propane and 0.7 kg of propene and, at 30° C., 0.5 bar of hydrogen and 7 bar of ethylene are metered in. Polymerization is carried out as in Example 1. Vacuum drying of the product gives 1.5 kg of ethylene-propylene copolymer wax having a VN of 19 cm 3  /g. DSC indicates a melting point of 106° C. and an enthalpy of fusion of 123 [J/g]. Further property data are shown in Table 1. 
     EXAMPLE 4 
     To prepare the catalyst, 1.5 mg of rac-dimethylsilylbis(2-methyl-4,5-benzindenyl)zirconium dichloride in 5 cm 3  of 10% strength by weight methylaluminoxane solution in toluene are used. The reactor from Example 1 is charged with 1 kg of propane and 3 kg of propene and at 30° C., 1.6 bar of hydrogen and 1.6 bar of ethylene are metered in. Polymerization is carried out as in Example 1. Vacuum drying of the product gives 1.90 kg of propylene-ethylene copolymer wax having a VN of 31 cm 3  /g. DSC indicates a melting point of 118° C. and an enthalpy of fusion of 82 [J/g]. Further property data are shown in Table 1. 
     The waxes prepared as described in Examples 1-4 were tested in printing ink and surface coating formulations in comparison with commercial waxes synthesized by the Ziegler-Natta process. 
     
                                           TABLE 1__________________________________________________________________________Physical properties of the waxes tested:          Melt Drop   viscosity point  Mn Density  Type mPa · s ° C. Mw/Mn g/mol g/cm.sup.3__________________________________________________________________________Test sample  Metallocene          350 at               124 2.4  990                           0.965  1, from Ex. 1 ethylene- 140° C.   homopolymer   wax,  Test sample Metallocene 40 at 135 2.1 1870 0.880  2, from Ex. 2 propene- 170° C.   homopolymer   wax,  Test sample Metallocene 640 at 107 2.5 2220 0.928  3, from Ex. 3 ethylene- 140° C.   propene-   copolymer wax,  Test sample Metallocene 1490 at 127 2.4 7071 0.871  4, from Ex. 4 propene- 170° C.   ethylene-   copolymer wax,  Comparative Ethylene 300 at 125 2.8 1500 0.970  sample 1 homopolymer 140° C.   wax prepared   using Ziegler-   Natta-catalysator.  Comparative Ethylene- 630 at 119 2.8 2500 0.930  sample 2 propene- 140° C.   copolymer- wax   prepared using   Ziegler-Natta   catatyst.__________________________________________________________________________ 
    
     EXAMPLES 5, 6 AND COMPARATIVE EXAMPLE 1 
     The test samples 1 and 2 and also comparative sample 1 were each micronized by comminution in an air jet mill (Chrispro-Jetmill MC 100, Micro-Macinazione SA). The micropowders were incorporated in an amount of 1.5% by weight into an offset ink (Novaboard cyan 4 C 86, K+E Druckfarben) by means of intensive stirring using a dissolver. A test print was produced (Prufbau multipurpose test printing machine, system Dr. Durner) on Phoenomatt 115 g/m2 paper (Scheufelen GmbH+Co KG) and the abrasion behavior was examined on an abrasion testing apparatus (abrasion tester, Prufbau Quartant) at a loading of 48 g/cm2, speed 15 cm/sec. The intensity of the color transferred to the test sheet was assessed (color difference in accordance with DIN 6174, measured using Hunterlab D 25-2, Hunter). 
     
                       TABLE 2______________________________________Result of testing in an offset ink when incorporated as micropowder                    Color difference                    100     200  Particle size d.sub.50 [μm] strokes strokes______________________________________   Comparison --            14.4  15.9   without wax  Example 5 Test sample 1 5.6 1.5 1.8  Example 6 Test sample 2 6.3 1.1 1.9  Comparative Comparative 8.3 2.2 2.7  Example 1 sample 1______________________________________ 
    
     The waxes of the invention give a finer powder and result in a lower color difference and thus have improved abrasion resistance. 
     EXAMPLE 7 AND COMPARATIVE EXAMPLE 2 
     10 parts of test sample 2 and comparative sample 1 were each heated to 100° C. in 30 parts of toluene while stirring. The clear solution formed was cooled to a temperature which was 30° above the cloud point and stirred into 60 parts of cold toluene. The mixture was allowed to cool to room temperature while continuing to stir. The resulting dispersion was incorporated in an amount of 1.0% by weight into an illustration gravure ink (type RR Grav rot, Siegwerk Farbenfabrik Keller, Dr. Rung+Co). A test print was produced (gravure test printing apparatus LTG 20, Einlehner Prufmaschinenbau) on paper of the type Allgau 60 g/m 2  (G.Haindl&#39;sche Papierfabriken KG) and tested as described in Example 5. 
     
                       TABLE 3______________________________________Result of testing in a gravure ink, incorporated as dispersion                  Color difference                             Color difference    after 20 strokes after 100 strokes              Fulltone                      Halftone                             Fulltone                                   Halftone______________________________________   Comparison 7       6.5    12.9  13.6   without wax  Example 7 Test sample 2 2.3 1.2 4.0 2.9  Comparative Comparative 3.0 2.0 4.4 3.5  Example 2 sample 1______________________________________ 
    
     The waxes of the invention result in a lower color difference and thus have improved abrasion resistance. 
     EXAMPLE 8 AND COMPARATIVE EXAMPLE 3 
     33 parts of test sample 3 and comparative sample 2 were each dissolved in 67 parts of mineral oil PKWF 6/9 (Haltermann N.V.) at 135° C. while stirring. The solution was processed on a three-roll mill to give a paste. The paste was incorporated in an amount of 1.5% by weight into an offset ink (Novaboard Cyan 4 C 86 wax-free; K+E Druckfarben GmbH+CO KG) and tested as described in Example 5. 
     
                       TABLE 4______________________________________Result of testing in an offset ink, incorporated as paste                    Color difference                after 100 strokes                            after 200 strokes______________________________________   Comparison   10.8        16.8   without wax  Example 8 Test sample 3 2.6 3.5  Comparative Comparative 3.5 4.7  Example 3 sample 2______________________________________ 
    
     EXAMPLE 9 AND COMPARATIVE EXAMPLE 4 
     Test sample 1 and comparative sample 1 were each tested using a method similar to Example 7. 
     
                       TABLE 5______________________________________Result of testing in a gravure ink, incorporated as dispersion                      Color difference after 20 strokes                  Fulltone   Halftone______________________________________    Comparison without                  7          6.5   wax  Example 9 Test sample 3 1.3 0.9  Comparative Comparative sample 2 1.4 1.3  Example 4______________________________________ 
    
     EXAMPLE 10 AND COMPARATIVE EXAMPLE 5 
     Test sample 4 and comparative sample 2 were each tested using a method similar to Example 7. 
     
                       TABLE 6______________________________________Result of testing in a gravure ink, incorporated as dispersion                      Color difference after 20 strokes                  Fulltone   Halftone______________________________________    Comparison without                  7          6.5   wax  Example 10 Test sample 4 1.1 0.8  Comparative Comparative sample 2 1.4 1.3  Example 5______________________________________ 
    
     EXAMPLES 11, 12 AND COMPARATIVE EXAMPLE 6 
     The micronized waxes described in Examples 5 and 6 were stirred into a standard nitrocellulose coating composition using a dissolver. The wax-containing surface coating composition was applied to a glass plate by means of a doctor blade (60 μm wet film thickness). The degree of gloss (matting effect) was assessed by means of a gloss measuring apparatus of the type micro-TRI-gloss (BYK-Gardner) after drying for 24 hours. 
     
                       TABLE 7______________________________________Testing of ethylene and propene homopolymer waxes in  a surface coating formulation when incorporated as micropowders                      Gloss (angle 60°)                  Wax        Wax    concentration concentration    2% by weight 4% by weight______________________________________    Comparison without                  140        140   wax  Example 11 Test sample 1 25 13  Example 12 Test sample 2 30 15  Comparative Comparative 32 17  Example 6 sample 1______________________________________ 
    
     The waxes of the invention display reduced surface gloss and an improved matting action. 
     EXAMPLES 13, 14 AND COMPARATIVE EXAMPLE 7 
     10 parts of wax were heated in 30 parts of xylene while stirring. The clear solution formed was cooled to a temperature which was 3° above the cloud point and stirred into 60 parts of cold xylene using a dissolver. The mixture was allowed to cool to room temperature while continuing to stir intensively. 20 or 40 parts of the 10% 25 strength wax dispersion were stirred into 80 to 60 parts respectively of a standard nitrocellulose coating composition. The wax-containing surface coating composition was tested as described in Example 11. 
     
                       TABLE 8______________________________________Result of testing of copolymer waxes in a surface coating formuation when incorporated as dispersion                      Gloss (angle 60°)                  Wax        Wax    concentration concentration    2% by weight 4% by weight______________________________________    Comparison without                  143        143   wax  Example 13 Test sample 3 15 4  Example 14 Test sample 4 16 7  Comparative Comparative 18 9  Example 7 sample 2______________________________________ 
    
     EXAMPLES 15, 16 AND COMPARATIVE EXAMPLE 8 
     2 or 4 parts of the test wax were dissolved in 18 or 16 parts respectively of hot xylene to give a clear solution. The solution was cooled to a temperature which was 3° above the cloud point of the wax and stirred into 80 parts of standard nitrocellulose coating composition. The mixture was allowed to cool to room temperature while stirring intensively. The surface coating composition was applied to a glass plate using a method similar to Example 11 and the degree of gloss was measured. 
     
                       TABLE 9______________________________________Result of incorporation by hot precipitation                      Gloss (angle 60°)                  Wax        Wax    concentration concentration    2% by weight 4% by weight______________________________________    Comparison without                  138        138   wax  Example 15 Test sample 3 17 8  Example 16 Test sample 4 16 9  Comparative Comparative 26 11  Example 8 sample 2______________________________________