PELLETIZATION OF A POLYMER STABILIZER MIXTURE

Abstract

The invention relates to a method for manufacturing a pellet in a pellet mill, which method comprises the steps of (A) pressing a mixture for compaction by a roller through a nozzle to obtain a strand, and (B) comminuting the strand to obtain the pellet, wherein the mixture for compaction comprises (i) 87 to 97 wt. % of a polymer stabilizer mixture polymer stabilizer mixture, which comprises the polymer stabilizers (i-1) 21 to 29 wt. % of tris(2,4-ditert-butylphenyl) phosphite (CAS-No. 31570-04-4), (i-2) 21 to 29 wt. % of tetrakis-[3-(3,5-ditert-butyl-4-hydroxy-phenyl)-propionyloxymethyl]methane (CAS-No. 6683-19-8), (i-3) 8 to 12 wt. % of a C16-C18 fatty acid calcium salt, (i-4) 36 to 44 wt. % of a calcium oxide, and wt. % of the polymer stabilizers (i-1), (i-2), (i-3) and (i-4) are based on the weight of the polymer stabilizer mixture, and (ii) 3 to 13 wt. % of a processing aid, which is a propylene-ethylene copolymer and which possesses a melting enthalpy below 100 J/g at 101.32 kPa. The pellet is useful for a dust-free handling of its polymer stabilizer mixture at a manufacturing of a stabilized polymer. Furthermore, a method for stabilizing a polymer, which is a polyolefin, a polystyrene or a mixture thereof, is disclosed, which comprises the dosing of the pellet to the polymer.

Claims

1.-32. (canceled)

33. A method for manufacturing a pellet in a pellet mill, which comprises a roller and a die with a nozzle, which method comprises the steps of (A) pressing a mixture for compaction by the roller through the nozzle to obtain a strand, and (B) comminuting the strand to obtain the pellet, wherein the mixture for compaction comprises the components (i) 87 to 97 wt. % of a polymer stabilizer mixture, which comprises the polymer stabilizers (i-1) 21 to 29 wt. % of tris(2,4-ditert-butylphenyl) phosphite (CAS-No. 31570-04-4), (i-2) 21 to 29 wt. % of tetrakis-[3-(3,5-ditert-butyl-4-hydroxy-phenyl)propionyloxymethyl]methane (CAS-No. 6683-19-8), (i-3) 8 to 12 wt. % of a C16-C18 fatty acid calcium salt, (i-4) 36 to 44 wt. % of a calcium oxide, and wt. % of the polymer stabilizers (i-1), (i-2), (i-3) and (i-4) are based on the weight of the polymer stabilizer mixture, and (ii) 3 to 13 wt. % of a processing aid, which is a propylene-ethylene copolymer and which possesses a melting enthalpy below 100 J/g at 101.32 kPa, wherein the melting enthalpy is determined by a differential scanning calorimetry according to EN ISO 11357-3, and wt. % of the components (i) and (ii) are based on the weight of the mixture for compaction.

34. The method according to claim 33, wherein the processing aid possesses a weight average molecular weight above 10000 Da and below 80000 Da, and wherein the weight average molecular weight of the processing aid is determined by gel permeation chromatography (GPC).

35. The method according to claim 33, wherein the processing aid possesses a melting peak temperature above 50? C. and below 85? C., wherein the melting peak temperature is determined by a differential scanning calorimetry according to EN ISO 11357-3.

36. The method according to claim 33, wherein the polymer stabilizer mixture contains (i-3) 8 to 12 wt. % of a C16-C18 fatty acid calcium salt and 80 to 100 parts by weight of the C16-C18 fatty acid calcium salt is calcium stearate or calcium palmitate and parts by weight are based on the overall amount of C16-C18 fatty acid calcium salt in the polymer stabilizer mixture, which is 100 parts by weight.

37. The method according to claim 33, wherein the calcium oxide is in the form of a powder and the powder is hydrophobized or untreated.

38. The method according to claim 37, wherein the powder is hydrophobized by treatment with a paraffin oil or a fatty acid.

39. The method according to claim 33, wherein the processing aid is a propylene-ethylene copolymer, which is a wax.

40. The method according to claim 33, wherein the mixture for compaction comprises (i) 89 to 96 wt. % of the polymer stabilizer mixture, and (ii) 4 to 11 wt. % of the processing aid.

41. The method according to claim 33, wherein the strand has a surface temperature above 45? C. and below 110? C., wherein the strand surface temperature is determined by measurement of its infrared irradiation.

42. The method according to claim 33, wherein the method comprises a step (pre-A) feeding the mixture for compaction into the pellet mill, wherein the mixture for compaction is in the form of a powder, and the step (pre-A) occurs before the step (A).

43. The method according to claim 33, wherein the pellet mill is a ring die pellet mill, wherein the die has a geometric form of a ring with an inner side and an outer side and the nozzle represent a pass from the inner side to the outer side, or the pellet mill is a flat die pellet mill, wherein the die has a geometric form of a planar plate with an upper side and a lower side and the nozzle represents a pass from the upper side to the lower side.

44. A pellet, which comprises the components (i) 87 to 97 wt. % of a polymer stabilizer mixture, which comprises the polymer stabilizers (i-1) 21 to 29 wt. % of tris(2,4-ditert-butylphenyl) phosphite (CAS-No. 31570-04-4), (i-2) 21 to 29 wt. % of tetrakis-[3-(3,5-ditert-butyl-4-hydroxy-phenyl)-propionyloxymethyl]methane (CAS-No. 6683-19-8), (i-3) 8 to 12 wt. % of a C16-C18 fatty acid calcium salt, (i-4) 36 to 44 wt. % of a calcium oxide, and wt. % of the stabilizers (i-1), (i-2), (i-3) and (i-4) are based on the weight of the polymer stabilizer mixture, and (ii) 3 to 13 wt. % of a processing aid, which is a propylene-ethylene copolymer and which possesses a melting enthalpy below 100 J/g at 101.32 kPa, wherein the melting enthalpy of the processing aid is determined by a differential scanning calorimetry according to EN ISO 11357-3, and wt. % of the components (i) and (ii) are based on the weight of the pellet.

45. The pellet according to claim 44, which has a shape of a round rod and the round rod has a diameter of a circle, which is between 2 mm and 4 mm and has a length of 1 to 3 times of the diameter of a circle.

46. A use of a pellet as defined in claim 44 for a dust-free handling of its components at manufacturing of a stabilized polymer, wherein the polymer is a polyolefin, a polystyrene or a mixture thereof.

47. A method for manufacturing of a stabilized polymer, which comprises the steps of (AP) dosing a pellet as defined in claim 44 into a polymer to obtain a pellet-polymer mixture, (BP) exposing the pellet-polymer mixture to a temperature in the range of 120 to 340? C. under mechanical stirring to obtain a stabilized polymer, wherein the polymer is a polyolefin, a polystyrene or a mixture thereof.

48. A mixture for compaction, which comprises the components (i) 87 to 97 wt. % of a polymer stabilizer mixture in the physical form of a powder, which comprises the polymer stabilizers (i-1) 21 to 29 wt. % of tris(2,4-ditert-butylphenyl) phosphite (CAS-No. 31570-04-4), (i-2) 21 to 29 wt. % of tetrakis-[3-(3,5-ditert-butyl-4-hydroxy-phenyl)propionyloxymethyl]methane (CAS-No. 6683-19-8), (i-3) 8 to 12 wt. % of a C16-C18 fatty acid calcium salt, (i-4) 36 to 44 wt. % of a calcium oxide, and wt. % of the polymer stabilizers (i-1), (i-2), (i-3) and (i-4) are based on the weight of the polymer stabilizer mixture, and (ii) 3 to 13 wt. % of a processing aid in the physical form of a powder, which is a propylene-ethylene copolymer and which possesses a melting enthalpy below 100 J/g at 101.32 kPa, wherein the melting enthalpy of the processing aid is determined by a differential scanning calorimetry according to EN ISO 11357-3, and wt. % of the components (i) and (ii) are based on the weight of the mixture for compaction.

Description

[0229] FIG. 1 shows pellets obtained from example D-11-1, which are placed on a millimeter paper.

[0230] FIG. 2 shows pellets obtained from example D-11-2, which are placed on a millimeter paper.

[0231] FIG. 3 shows pellets obtained from example D-11-3, which are placed on a millimeter paper.

[0232] FIG. 4 shows pellets obtained from example D-11-4, which are placed on a millimeter paper.

[0233] FIG. 5 shows pellets obtained from example D-11-5, which are placed on a millimeter paper.

[0234] FIG. 6 shows pellets obtained from example D-11-6, which are placed on a millimeter paper.

[0235] FIG. 7 shows pellets obtained from example D-11-7, which are placed on a millimeter paper.

[0236] The following examples illustrate further the invention without limiting it. Percentage values are percentage by weight if not stated differently.

[0237] A) Methods for Characterization

[0238] Mean particle size is determined, if not otherwise stated, by a Camsizer P4 from the Company Retsch Technology GmbH via digital image analysis. The measuring principle is a dynamic image analysis according to ISO 13322-2.

[0239] Bulk density is measured complying to DIN EN ISO 17892-3.

[0240] Melt flow index of a polymer is measured according to ISO 1133 on a Goettfert MI-Robo with the specifically stated parameters.

[0241] Differential scanning calorimetry (DSC) is measured according to EN ISO 11357-3 at atmospheric pressure. Heating cycles are (a) 0? C. to 200? C. at 10? C./min and 30 mL/min N.sub.2, (b) 200? C. to 0? C. at 10? C./min and 30 mL/min N.sub.2, (C) 0? C. to 200? C. at 10? C./min and 30 mL/min N.sub.2. Melting range, melting peak temperature and melting enthalpy are determined at heating cycle (c).

[0242] High temperature gel permeation chromatography (HT-GPC) is measured according to ISO 16014-4. As an apparatus, an Agilent PL-GPC 220 with RI detector is used. As a precolumn, one Agilent PFgel Olexis Guard 50?7.5 mm column (part No. PL1110-1400) is used. As columns, three Agilent PLgel Olexis 13 ?m 300?7.5 mm columns (part No. PL1110-6400) are used. The column temperature is 150? C. The calibration standards are polystyrene and High EasiVial GPC/SEC calibration standards from Agilent (part No. PL2010-0201 and part No. PL2010-0202). Trichlorobenzene is used as the eluent with a flow rate of 1 mL/min, a sample concentration of 3 mg/mL and an injection volume of 200 ?L. A determined number average molecular weight Mn and a determined weight average molecular weight Mw are used to calculate a polydispersity index (PD) as the ratio between Mw and Mn.

[0243] Sieve analysis is conducted by a Camsizer P4 from the company Retsch Technology GmbH via digital image analysis. The measuring principle is a dynamic image analysis according to ISO 13322-2) with D10, D50 and D90 values.

[0244] The Norner attrition test is a test using a vibrating sieve shaker and glass beads to mechanically treat the tested form. An initial sieve analysis is conducted for 1 minute followed by further sieving using glass balls on the sieve decks to mechanically impact the material and measure the change of the sieve fractions after 5, 10 and 20 minutes. Sieves selected are bottom up: 200 ?m, 500 ?m, 1 mm, 1.6 mm, 2.5 mm and 4 mm. The used glass balls (company Sigmund Lindner GmbH, type P) are of 16 mm?0.02 mm, weight 5.36 g/glass ball and made of soda lime glass with fine matt surface.

[0245] The test procedure is as follow: [0246] 1. The sieve shaker without glass beads is charged with 50 g of a sample and the sieving with amplitude 1 mm is conducted for 1 minute. Measuring of mass on each sieve tray and sieve pan [0247] 2. Add 8 glass balls on sieve 500 ?m; 9 glass balls on sieve 1.0 mm, 10 on sieve 1.6 mm and 11 on sieve 2.5 mm. Proceed sieving for 5 minutes then measure mass on each sieve tray and sieve pan. [0248] 3. Proceed sieving for another 5 minutes, repeat weighing procedure. [0249] 4. Proceed sieving for another 10 minutes, repeat weighing procedure.

[0250] A Retsch Sieve Shaker AS 200 control from the company Retsch GmbH is used as sieve shaker.

[0251] Total fines are the sum of all material, which is collected from bottom plate and 200 ?m mesh sieve. Accordingly, the fragments of a sample, which are generated under attrition stress and fall through a 500 ?m mesh sieve (<500 ?m), are considered fines. The particle size fraction in wt. %<500 ?m after 20 minutes is the key result (Norner value) to determine abrasion and impact resistance of the tested form. The range of results can vary from 0% for extremely stable to 100% for extremely unstable.

[0252] An average weight of pellets is measured by taking a certain number of pellets (around 60 pellets), weighing the certain number of pellets to obtain an overall weight and dividing the overall weight by the certain number of the pellets.

[0253] An average length of the pellets is calculated by multiplying the average weight of pellets with an assumed density of 0.95 g/cm.sup.3 and dividing by the circular area of a circle with a pellet diameter of 3 mm.

[0254] B) Starting Material

[0255] SM-PS-1: Irciafos 168

[0256] Irgafos 168 (TM, commercially available from BASF SE, melting point between 180-183? C.), which contains tris(2,4-ditert-butylphenyl) phosphite (CAS-No. 31570-04-4) as depicted below

##STR00006##

in the form of a powder, i.e. a loose bulk material with a bulk density of 467 g/L and a mean particle size of 400 ?m.

[0257] SM-PS-2: Irganox 1010

[0258] Irganox 1010 (TM, commercially available from BASF SE, melting point between 113-126? C.), which contains tetrakis-[3-(3,5-ditert-butyl-4-hydroxy-phenyl)-propionyloxymethyl]methane (CAS-No. 6683-19-8) as depicted below

##STR00007##

in the form of a powder, i.e. a loose bulk material with a bulk density of 530-630 g/L and a mean particle size of 141 ?m.

[0259] SM-PS-3: Ceasit FI VEG

[0260] Ceasit FI VEG (TM, commercially available from Baerlocher GmbH, melting point between 140-160? C.) is a vegetable-based calcium stearate, which contains C16-18-fatty acids calcium salts for example with a stearic acid calcium salt (2:1) (CAS-No. 1592-23-0) as depicted below

##STR00008##

in the form of a powder, i.e. a loose bulk material with a bulk density of 200-400 g/L and a mean particle size of 90 ?m.

[0261] SM-PS-4: Kezadol DAB-P

[0262] Kezadol DAB-P (TM, commercially available from Kettlitz-Chemie GmbH & Co. KG, melting point >>400? C.) is a calcium oxide (CAS-No. 1305-78-8) powder treated with a paraffin oil produced according to DAB 10 (Deutsches Apothekerbuch 10). Kezadol DAB-P has an active calcium oxide content of approximately 90% and is a loose bulk material with a bulk density of 650 g/L and a mean particle size of 6-7 ?m.

[0263] SM-PA-1: Licocene PP 1302

[0264] Licocene PP 1302 (TM, commercially available from Clariant, employed commercial technical form: fine grain) is a propylene-ethylene copolymer wax (CAS-No. 9010-79-1), which is synthesized with a metallocene catalyst from propylene and ethylene. Branching of the long polymeric chains occurs by short chains (CH.sub.3). Some physical-chemical properties are measured and depicted in table B-1.

[0265] Technical data sheet states a density at 23? C. according to ISO 1183 of 0.87 g/cm.sup.3.

[0266] Technical data sheet states a drop point according to ASTM D 3954 of 87-93? C.

[0267] Technical data sheet states a viscosity at 170? C. according to DIN 53019 of 150-250 mPas.

[0268] Sieve analysis of the material in the technical form fine grain is measured and depicted in table B-2. A bulk density of 338 g/L is measured. The material in its technical form fine grain is employed for compaction.

[0269] SM-PA-2: Petrolite EP-700

[0270] Petrolite EP-700 (TM, commercially available from Baker Hughes) is a propylene-ethylene copolymer wax (CAS-No. 9010-79-1). Controlled branching of the long polymeric chains occurs by short chains from propylene (CH.sub.3). Some physical-chemical properties are measured and depicted in table B-1.

[0271] Technical data sheet states a drop melting point according to ASTM D-127 of 96? C.

[0272] Technical data sheet states a viscosity at 99? C. of 12 pcs (120 mPas).

[0273] Petrolite EP-700 is milled in a disc mill PF 300 from Pallmann. Sieve analysis of the obtained ground material is measured and depicted in table B-2. A bulk density of the ground material of 473 g/L is measured. The ground material is employed for compaction.

[0274] SM-PA-3: Dow PG 7008

[0275] Dow PG 7008 (TM, commercially available from Dow Chemicals) is a low density polyethylene (CAS-No. 9002-88-4). Some physical-chemical properties are measured and depicted in table B-1

[0276] Technical data sheet states a density at 23? C. according to ASTM D-792 of 0.918 g/cm.sup.3.

[0277] Technical data sheet states a melting temperature (DSC) of 106? C.

[0278] Technical data sheet states a vicat softening temperature according to ISO 306/A of 89.0? C.

[0279] Technical data sheet states a melt index (190? C./2.16 kg) according to ISO 1133 of 7.7 g/10 min.

[0280] Dow PG 7008 is milled in a disc mill PF 300 from Pallmann. Sieve analysis of the obtained ground material is measured and depicted in table B-2. A bulk density of the ground material of 285 g/L is measured. The ground material is employed for compaction.

[0281] SM-PA-4: Borflow HL 708 FB

[0282] Borflow HL 708 FB (TM, commercially available from Borealis) is a polypropylene (CAS-No. 9003-07-0). Some physical-chemical properties are measured and depicted in table B-1.

[0283] Technical data sheet states a melting temperature (DSC) of 158? C.

[0284] Technical data sheet states a melt index (130? C./2.16 kg) according to ISO 1133 of 800 g/10 min.

[0285] Borflow HL 708 FB is milled in a disc mill PF 300 from Pallmann. Sieve analysis of the obtained ground material is measured and depicted in table B-2. A bulk density of the ground material of 365 g/L is measured. The ground material is employed for compaction.

[0286] SM-PA-5: Licocene PP 1502

[0287] Licocene PP 1502 (TM, commercially available from Clariant, employed commercial technical form: fine grain) is a propylene-ethylene copolymer wax (CAS-No. 9010-79-1), which is synthesized with a metallocene catalyst from propylene and ethylene. Branching of the long polymeric chains occurs by short chains (CH.sub.3). Some physical-chemical properties are measured and depicted in table B-1.

[0288] Technical data sheet states a density at 23? C. according to ISO 1183 of 0.87 g/cm.sup.3.

[0289] Technical data sheet states a drop point according to ASTM D 3954 of 83-90? C.

[0290] Technical data sheet states a viscosity at 170? C. according to DIN 53019 of 1500-2100 mPas.

[0291] Sieve analysis of the material in the technical form fine grain is measured and depicted in table B-2. A bulk density of 374 g/L is measured. The material in its technical form fine grain is employed for compaction.

TABLE-US-00001 TABLE B-1 measured physical-chemical properties of starting materials processing aids DSC measurement melting melting peak melting HT-GPC measurement starting commercial range tempera- enthalpy Mn Mw material name [? C.] ture [? C.] [J/g] [Da] [Da] PD SM-PA-1 Licocene 24-95 76 23 6833 17285 2.53 PP 1302 SM-PA-2 Petrolite 27-104 88 218 1335 1532 1.15 EP-700 SM-PA-3 Dow PG 25-116 106 117 30176 367733 12.2 7008 SM-PA-4 Borflow HL 120-173 157 109 25132 189565 7.54 708 FB SM-PA-5 Licocene 45-95 73 13 16356 39302 2.40 PP 1502

TABLE-US-00002 TABLE B-2 sieve analysis starting material Q3 10% [mm] Q3 50% [mm] Q3 90% [mm] SM-PA-1 0.414 0.836 1.583 SM-PA-2 (ground) 0.324 0.710 1.538 SM-PA-3 (ground) 0.225 0.484 1.091 SM-PA-4 (ground) 0.359 0.716 1.145 SM-PA-5 0.482 0.874 1.278

[0292] C) Preparation of Mixtures for Compaction

[0293] Mixtures for compaction consisting of polymer stabilizers and a processing aid are prepared by blending the starting materials as depicted in table C-11 in a 100-L MTI blender for 5 minutes at room temperature.

TABLE-US-00003 TABLE C-11 mixtures for compaction polymer amount processing amount physical mixture-No. stabilizer [%] aid [%] form .sup.c) C-M-11 .sup.b) SM-PS-1 25 none powder SM-PS-2 25 SM-PS-3 10 SM-PS-4 40 C-M-12 .sup.a) SM-PS-1 23.75 SM-PA-1 5 powder SM-PS-2 23.75 SM-PS-3 9.5 SM-PS-4 38 C-M-13 .sup.a) SM-PS-1 23 SM-PA-1 8 powder SM-PS-2 23 SM-PS-3 9.2 SM-PS-4 36.8 C-M-14 .sup.a) SM-PS-1 23 SM-PA-5 8 powder SM-PS-2 23 SM-PS-3 9.2 SM-PS-4 36.8 C-M-15 .sup.b) SM-PS-1 23 SM-PA-2 8 powder SM-PS-2 23 SM-PS-3 9.2 SM-PS-4 36.8 C-M-16 .sup.b) SM-PS-1 23 SM-PA-3 8 powder SM-PS-2 23 SM-PS-3 9.2 SM-PS-4 36.8 C-M-17 .sup.b) SM-PS-1 23 SM-PA-4 8 powder SM-PS-2 23 SM-PS-3 9.2 SM-PS-4 36.8 Food notes: .sup.a) inventive .sup.b) comparative .sup.c) at room temperature and atmospheric pressure

[0294] D) Pellets by a Compaction with a Flat Die Pellet Mill

[0295] A flat die pellet mill, i.e. a Kahl Pelletizer Model 14-175, is used for compaction trials of materials as stated in table D-11. A Kahl flat die pellet mill is depicted for example in the Handbuch fuer Kunststoff Additive, editors R. D. Maier, M. Schiller, Carl Hanser Verlag, Munich, ISBN 978-3-446-22352-3, 4th edition, 2016, page 1189, picture 14.9. The Kahl Pelletizer Model 14-175 possesses a fix flat die, which is equipped with nozzles, e.g. nozzles with a nozzle diameter of 3 mm and a press length of 6 mm or 10 mm. The diameter of the flat die is 175 mm. The nozzles expand with an angle of about 60? in flow direction (top down) of the flat die. The nozzle diameter is defined herein as the smallest diameter of the cylindric channel of the nozzle and press length is a distance, where the smallest diameter applies. The cylindric channel of the nozzle might expand after the press length, but the expanded part of the cylindric channel does not contribute for building up friction by the material to be compacted. The specifically applied nozzle diameter and press lengths are stated in table D-11. The material for compaction is dosed at room temperature by a volumetric single screw feeder, which is placed above the pellet press section of the flat die pellet mill, by gravimetry into the pellet press section, which comprises the die with its nozzles and two rollers. The rollers, each with a diameter of 130 mm and a width 29 mm, have a flat surface. They are connected by a central vertical shaft and roll in a circle on the round flat die.

[0296] In the pellet press section, the two rollers push the material into the nozzles of the flat die, where the material is compacted and heated up by shear forces to a temperature, at which the processing aid starts to soften and in a sintering process the compacted material is granulated to cylindrical pellets. For beginning the process, the rotation of the rotors is set to 5 (=78 rpm). The material for compaction is fed as a powder into the press section. An initial starting phase of around 15 minutes is necessary until a stable running of the process is achieved. While initially a powder of the material for compaction is flowing through the nozzles, this changes towards formation of a strand at some materials for compaction and the flat die, the rollers and the nozzles are reaching a stable temperature. A temperature, which would be too high for a material for compaction, can result in a generation of a pasty mass, which blocks a further feeding of the material for compaction. At the outlet of the nozzle, the strand is cut/broken by four rotating knifes with an adjustable distance to the flat die to generate pellets with a length of around 1 to 3 times of the diameters of the pellets, i.e. around 3 mm to 9 mm. Ideally, the variation in length is minimal but a certain variation cannot be avoided due to the cutting/breaking. Table D-11 states whether pellets are obtained and thus also whether a strand was formed. The temperature of the flat die is measured by a sensor mounted form outside through a bore into the die. Once the process is running stable, the temperature of the collected pellets is measured by a manual IR-temperature sensor through measuring contactless the emitted IR irradiation and stated in table D-11 as surface temperature of the pellet. The flat die itself is not heated or cooled but experiences a warming due to the occurring friction of the material for compaction. The obtained pellets are sieved with a 1.6 mm sieve (200 mm diameter vibrating lab sieve) to separate fines from the obtained pellets. The amount of fines removed by sieving based on the overall amount of material for compaction is stated in table D-1 and D-3. The removed fines can be directly reused as material to be compacted. The pellets have cooled down to room temperature. If pellets are obtained, a Norner attrition test of the pellets after sieving is conducted and results are depicted in table D-11. Further characterizations of the obtained pellets are depicted in table D-12. Pictures of the pellets obtained at examples D-11-1 to D-11-7 are depicted at FIG. 11 to FIG. 17.

TABLE-US-00004 TABLE D-11 flat die pellet mill compactions and attrition test results surface material tempera- for nozzle ture of removed Norner example compac- composition size .sup.c) the pellet fines test No. tion [%] [mm] [? C.] pellets [%] [%] D-11-1 .sup.b) C-M-11 SM-PS-1 (25) 3 ? 10 81 yes 16 67 SM-PS-2 (25) SM-PS-3 (10) SM-PS-4 (40) D-11-2 .sup.a) C-M-12 SM-PS-1 (23.75) 3 ? 10 73 yes 13 39 SM-PS-2 (23.75) SM-PS-3 (9.5) SM-PS-4 (38.0) SM-PA-1 (5) D-11-3 .sup.a) C-M-13 SM-PS-1 (23) 3 ? 10 70 yes 15 26 SM-PS-2 (23) SM-PS-3 (9.2) SM-PS-4 (36.8) SM-PA-1 (8) D-11-4 .sup.a) C-M-14 SM-PS-1 (23) 3 ? 10 75 yes 12 10 SM-PS-2 (23) SM-PS-3 (9.2) SM-PS-4 (36.8) SM-PA-5 (8) D-11-5 .sup.b) C-M-15 SM-PS-1 (23) 3 ? 10 71 yes 21 70 SM-PS-2 (23) SM-PS-3 (9.2) SM-PS-4 (36.8) SM-PA-2 (8) D-11-6 .sup.b) C-M-16 SM-PS-1 (23) 3 ? 10 83 yes 19 62 SM-PS-2 (23) SM-PS-3 (9.2) SM-PS-4 (36.8) SM-PA-3 (8) D-11-7 .sup.b) C-M-17 SM-PS-1 (23) 3 ? 10 88 yes 25 65 SM-PS-2 (23) SM-PS-3 (9.2) SM-PS-4 (36.8) SM-PA-4 (8) Food notes: .sup.a) inventive .sup.b) comparative .sup.c) nozzle diameter ? press length

[0297] From the results of the table D-11: [0298] example D-11-1 shows that the reference blend C-M-11 without processing aid can be pelletized, but the Norner attrition test result is poor; [0299] examples D-11-2, D-11-3 and D-11-4 show the best (lowest) Norner values; this shows that SM-PA-1 and SM-PA-5 lead to pellets with a significantly better Norner attrition test results than without a processing aid or with the other processing aids; [0300] examples D-11-2, D-11-3 and D-11-4 versus example D-11-5 show than SM-PA-1 and SM-PA5 lead to pellets with a significantly better Norner attrition test result than SM-PA-2 despite of all three processing aids being a propylene-ethylene copolymer wax; [0301] example D-11-5 and D-11-7 show that the amount of fines, which are generated at the process itself and removed by the 1.6 mm sieve, is not a reliable indicator for a beneficial Norner attrition test result; [0302] example D-11-2 versus example D-11-3 shows that a higher amount of processing aid results in better Norner results.

TABLE-US-00005 TABLE D-12 pellet characterization material average average for pellet di- pellet pellet Norner example compac- composition ameter .sup.c) length .sup.d) weight picture test .sup.e) No. tion [%] [mm] [mm] [mg] at Fig. [%] D-11-1 .sup.b) C-M-11 SM-PS-1 (25) 3 2.1 14.0 11 67 SM-PS-2 (25) SM-PS-3 (10) SM-PS-4 (40) D-11-2 .sup.a) C-M-12 SM-PS-1 (23.75) 3 2.0 13.5 12 39 SM-PS-2 (23.75) SM-PS-3 (9.5) SM-PS-4 (38.0) SM-PA-1 (5) D-11-3 .sup.a) C-M-13 SM-PS-1 (23) 3 1.9 12.7 13 26 SM-PS-2 (23) SM-PS-3 (9.2) SM-PS-4 (36.8) SM-PA-1 (8) D-11-4 .sup.a) C-M-14 SM-PS-1 (23) 3 1.9 12.8 14 10 SM-PS-2 (23) SM-PS-3 (9.2) SM-PS-4 (36.8) SM-PA-5 (8) D-11-5 .sup.b) C-M-15 SM-PS-1 (23) 3 1.7 11.7 15 70 SM-PS-2 (23) SM-PS-3 (9.2) SM-PS-4 (36.8) SM-PA-2 (8) D-11-6 .sup.b) C-M-16 SM-PS-1 (23) 3 1.9 12.7 16 62 SM-PS-2 (23) SM-PS-3 (9.2) SM-PS-4 (36.8) SM-PA-3 (8) D-11-7 .sup.b) C-M-17 SM-PS-1 (23) 3 2.1 14.0 17 65 SM-PS-2 (23) SM-PS-3 (9.2) SM-PS-4 (36.8) SM-PA-4 (8) Food notes: .sup.a) inventive .sup.b) comparative .sup.c) caused by the diameter of the nozzles .sup.d) calculated from average pellet weight .sup.e) results from table D-11 depicted again

[0303] From the results of the table D-12: [0304] all examples are in a similar range of an average pellet weight; the average weight is not a reliable indicator for a beneficial Norner attrition test result.