Process for the preparation of ABS graft copolymers and ABS molding compositions therefrom with improved gloss stability

Abstract

The invention relates to a process for the preparation of acrylonitrile-butadiene-styrene graft copolymers where specific process conditions (i.e. temperature increase during polymerization, amount of initiator, no molecular weight regulator) in the graft polymerization step are applied. Further described are thermoplastic ABS molding compositions comprising said graft copolymers, a styrenic copolymer matrix and additives, which can be produced at large scale and show an improved gloss stability.

Description

[0001] Process for the preparation of ABS graft copolymers and ABS molding compositions therefrom with improved gloss stability

[0002] Description

[0003] The invention relates to a process for the preparation of acrylonitrile-butadiene-styrene graft copolymers, graft copolymers obtained by said process, and thermoplastic acrylo- nitrile-butadiene-styrene (ABS) molding compositions comprising said graft copolymers, which can be produced at large scale, and which show an improved gloss stability and balanced mechanical and optical properties.

[0004] It is known that ABS polymer products with high surface quality, i.e. a uniform gloss level, require a low amount of salt specks on the surface. Salt specks often stem from deposits on the extruder screw of the ABS process, which typically is a single step process to produce ABS materials out of SAN-copolymers, which are fed, in particular as melt, as granule or powder feed, to the extruder, and ABS rubber coming from precipitation, eventually sintering and centrifugation.

[0005] Therefore, some ABS polymer producers add another process step, before the ABS extrusion process, which is a rubber drying step in a rotary dryer, flash dryer and / or fluid bed dryer. Typically, these pre-drying steps keep the precipitating agent, e.g. magnesium sulfate, within the rubber, however as a finely dispersed powder which does not result in strongly visible surface defects. As a flipside, such a process consumes extra energy and requires extra assets, hence is more expensive than a single ABS extrusion step using ABS rubber not being pre-dried. Another, very important reason against the rubber pre-drying step is the danger of ignition. Finely dispersed, reactive polymers like polybutadiene are destined to ignite if not properly protected by a large amount of stabilizer and / or protective atmosphere, such as nitrogen.

[0006] For the production of thermoplastic ABS molding compositions moist, or more or less partially dewatered rubber can be obtained from slurries by pressing out the water mechanically in presses, including screw presses. This is frequently carried out by using an apparatus which has strainer barrels through which the water can flow away in the same way as through a sieve. The rubber obtained in this manner, which still has a certain residual moisture content, is then pressed to form bales or is granulated.

[0007] According to WO 2015 / 000873, thermoplastic compositions can be prepared with reduced salt concentration, which have a smooth surface with low amount of visible salt specks. However, it is not only important to reduce salt specks in order to achieve a high surface quality. Large ABS polymer particles, especially those in mass-ABS, have a negative impact on surface quality, especially on gloss. Large rubber particles on the surface scatter the light and therefore the respective ABS part appears dull and gloss reduced, respectively.

[0008] WO 2016 / 184765 and WO 2017 / 093468 describe a mixture of two ABS graft copolymers B-l and B-ll, wherein graft copolymer B-l is obtained by emulsion polymerization of a mixture of styrene and acrylonitrile in the presence of a polybutadiene graft rubber basis B1-A (Dso: 230 to 330 nm) and a polybutadiene graft rubber basis B1-B (D50: 340 to 480 nm), and graft copolymer B-ll is obtained by emulsion polymerization of a mixture of styrene and acrylonitrile in the presence of a polybutadiene graft rubber basis B1-C (D50: 10 to 220 nm). The graft polymerization is carried out such that the temperature increases by at least 10°C during the polymerization, e.g. from 55 to 65°C to 75 to 85°C. In particular, the graft polymerization is carried out within 2 to 10 hours, e.g. 3 to 7 hours.

[0009] Exemplarily, the graft polymerization is carried out in each case by means of inorganic persulfate salt initiation, wherein the graft rubber basis and 0.25 parts by weight of persulfate salt are first provided at 60°C, then the monomer mixture and molecular weight regulator are added over 5 hours, and in parallel 0.25 parts by weight of persulfate salt are metered over a period of 5 hours. The reaction temperature was raised from 60 to 81°C within 3 hours. The obtained dispersions of the two ABS graft copolymers B-l and B-ll were mixed and co-precipitated. ABS molding compositions comprising said mixture of ABS graft copolymers and rubber-free SAN copolymers have improved surface properties. However, the preparation of these ABS molding composition have the disadvantage that the process requires the separate preparation of the two ABS graft copolymers B-l and B-ll which then have to be co-precipitated. This results in high preparative efforts as well as high equipment costs which are also reflected in the total production costs.

[0010] The patent applications WO 2023 / 083936, WO 2022 / 229335 and WO 2022 / 229347 describe thermoplastic ABS molding compositions comprising a SAN copolymer matrix A, an ABS-graft copolymer B, and one or more additives D. The monomers B21 / B22 used in the grafting process are fed in the range of 1 to 10 hours, preferably in 1.5 to 6 hours, to the agglomerated graft rubber basis B1. Exemplified is the addition of a styrene / acry- lonitrile monomer mixture over two hours and 44 minutes to the agglomerated latex of the graft rubber basis B1 to which before a first portion initiator was added at 68°C. Over said time period the temperature was increased to 80°C. After the completed monomer addition, a second portion initiator (same amount as first portion) was added and after continued polymerization graft copolymer B was obtained.

[0011] However, also with the ABS molding compositions disclosed in WO 2023 / 083936, WO 2022 / 229335 and WO 2022 / 229347 often difficulties appear when injection molding conditions are non-optimal due to fluctuating temperatures or due to reduced (low) mold temperatures. It turned out that the injection molded parts have different gloss and reduced gloss levels under different conditions. In particular in large parts, the injection molding conditions often fluctuate which then results in molding parts with areas of higher and lower gloss levels which is unfavorable. However, it has some cost advantages in the injection molding process when the temperature of the mold can be reduced. Often for cycle time and cost reasons, higher mass and / or lower mold temperatures during injection molding are applied than for a good result would be necessary. In the instant patent application, these conditions are called non-optimal injection molding conditions. Conditions for good results are called good injection molding conditions and typically employ higher mold temperatures during injection molding, for example mold temperatures of 70°C or more.

[0012] One objective of the instant invention is to provide a process for the preparation of ABS graft copolymers and to provide ABS molding compositions comprising said graft copolymers having a good gloss stability under different molding conditions - including non- optimal conditions - for injection molding and having further well-balanced mechanical and optical properties. A further objective of the instant invention is to provide ABS molding compositions comprising said graft copolymers having a good gloss stability under different molding conditions, wherein the process for producing the ABS molding compositions requires low preparative efforts and thus low overall production costs.

[0013] Surprisingly, it turned out that the polymerization conditions during the grafting step in the preparation of an ABS graft copolymer have a tremendous effect on the gloss stability (the gloss performance at non-optimal injection molding conditions compared to the gloss performance at good injection molding conditions).

[0014] One aspect of the invention is a process for the preparation of a graft copolymer B (component B) comprising:

[0015] B1 : 30 to 90 wt.-%, preferably 40 to 85 wt.-%, - based on the dry weight of B - ,of at least one graft rubber basis (component B1) having a glass transition temperature of less than 0°C, comprising:

[0016] B11 : 50 to 100 wt.-%, preferably 79 to 100 wt.-%, - based on the total weight of monomers forming B1 , - of one or more of butadiene or isoprene (component B11), preferably butadiene, and B12: 0 to 50 wt.-%, preferably 0 to 21 wt.-%, - based on the total weight of monomers forming B1 , - of at least one further monomer (component B12) selected from the group consisting of: styrene, a-methylstyrene, acrylonitrile, methacrylonitrile, methyl methacrylate, maleic acid anhydride, and N-phenylmaleimide, preferably styrene, where (B11) and (B12) sum to 100 wt.-%;

[0017] B2: 10 to 70 wt.-%, preferably 15 to 60 wt.-%, - based on the dry weight of B -, of one or more graft sheaths B2 (component B2) comprising:

[0018] B21 : 50 to 90 wt.-%, preferably 70 to 90 wt.-%, - based on the total weight of monomers forming B2 -, of styrene, a-methylstyrene and / or p-me- thyl-styrene (component B21), in particular styrene;

[0019] B22: 10 to 50 wt.-%, preferably 10 to 30 wt.-%, - based on the total weight of monomers forming B2 -, of (meth)acrylonitrile (component B22), in particular acrylonitrile;

[0020] B23: 0 to 40 wt.-%, - based on the total weight of monomers forming B2 -, of one or more co-polymerizable monomers (component B23), preferably Ci-Cs-acrylates and / or methyl methacrylate, where (B21), (B22) and (B23) sum to 100 wt.-%, and where components B1 and B2 sum to 100 wt.-%. which process comprises the following steps:

[0021] (i) polymerizing components B11 and optionally B12 to obtain at least one graft rubber basis B1 ;

[0022] (ii) agglomerating the graft rubber basis B1 (obtained in step (i)) by adding an agglomeration agent, preferably an agglomerating copolymer (BC); and

[0023] (iii) graft polymerization of components B21 , B22, and optionally B23 in presence of the agglomerated graft rubber basis B1 (obtained in step (ii)) by feeding at least one polymerization initiator in at least two, preferably two, portions, whereof a first portion of the initiator is fed at the start before feeding and copolymerizing components B21 , B22, and optionally B23 (forming the one or more graft sheaths B2) to obtain graft copolymer B; wherein in step (iii) at least one of the process conditions a) and / or b) in combination with process condition c) is applied: a) temperature increase during the feeding of components B21 , B22, and optionally B23 within 1 hour and 45 minutes or less to a temperature of at least 10°C higher than the temperature at the start of feeding said components (B21 , B22, and optionally B23); b) amount of the initiator applied at the start (1stportion) is at least 52 % by weight, preferred at least 55 % by weight, more preferred at least 60% by weight, based on the total amount of initiator applied in step (iii); and c) no molecular weight regulator or chain transfer agent is used in step (iii).

[0024] The glass transition temperature may be measured by dynamical mechanical analysis with an applied frequency of 1 Hz.

[0025] The weight median particle size Dso is the diameter which divides the population exactly into two equal parts. 50% by weight of the particles are larger than the weight median particle size Dso and 50% by weight are smaller.

[0026] The weight mean average particle diameter Dw (or De Brouckere mean particle diameter) is an average size based on unit weight of particle. The definition for the weight mean average particle size diameter Dw can be given as:

[0027] Dw = sum ( ni * Dj4) / sum ( n; * Dj3) ni: number of particles with the diameter Dj

[0028] See G. Lagaly, O. Schulz, R. Ziemehl: Dispersionen und Emulsionen: Eine Einfuhrung in die Kolloidik feinverteilter Stoffe einschlieBlich der Tonminerale, Darmstadt: Steinkopf- Verlag 1997, ISBN 3-7985-1087-3, page 282, formula 8.3b. The summation is normally performed from the smallest to largest diameter of the particles size distribution. It should be mentioned that for a particles size distribution of particles with the same density the volume mean average particle size diameter Dv is equal to the weight mean average particle size diameter Dw.

[0029] The particle size distribution, the weight mean average particle diameter Dw and the weight median particle size Dso can be determined using a disc centrifuge (e.g. at a disk rotational speed of 24 000 rpm using for example DC 24000 by CPS Instruments Inc.; the method is described in detail in the experimental section for the determination of the weight mean average particle diameter Dw and the weight median particle size Dso of components B1 , B, and BC).

[0030] The dry weights of the components (i.e. B, B1 , BC) mentioned with respect to the process according to the invention correspond to the solids content of the latex of said components, therefore excluding contained or absorbed liquids (e.g. water or unbound monomers). The solids content may be measured after drying the latex samples at 180°C for 25 min in a drying cabinet.

[0031] With respect to the description of the compositions of the polymeric components (e.g. A, B, B1 , B2, BC) as used herein, it is generally understood by those skilled in the art that terms relating to monomers, e.g. terms such as "styrene", "acrylonitrile", "butadiene", etc., refer to the structural units derived from the respective monomer and are meant to be embedded in the (co)polymer structure.

[0032] According to one embodiment of the process according to the invention in step (iii) process conditions a) and c) are combined.

[0033] According to a further embodiment of the process according to the invention in step (iii) process conditions b) and c) are combined.

[0034] According to a further embodiment of the process according to the invention in step (iii) process conditions a), b) and c) are combined.

[0035] According to a preferred embodiment of the process according to the invention in step (iii) process conditions a), b) and c) are combined.

[0036] Component B

[0037] Graft Rubber Basis (Component B1)

[0038] In step (i) of the process according to the invention components B11 and optionally B12 are polymerized to obtain at least one graft rubber basis B1.

[0039] Component B11 employed is butadiene and / or isoprene, preferably butadiene. Preferably component B12 is a-methylstyrene and / or styrene, preferably only styrene.

[0040] Preference is given to a graft rubber basis B1 comprising 79 to 100 wt.-%, more preferably 80 to 99 wt.-%, even more preferably 90 to 98 wt.-%, - based on the total weight of monomers forming B1 -, of component B11 and 0 to 21 wt.-%, more preferably 1 to 20 wt.-%, even more preferably 2 to 10 wt.-%, - based on the total weight of monomers forming B1 -, of component B12, where (B11) and (B12) sum to 100 wt.-%.

[0041] Particular preference is given to a graft rubber basis B1 comprising butadiene (B11) and styrene (B12) in the above-mentioned composition. Component B1 as graft rubber basis has a glass transition temperature of less than 0°C measured by dynamical mechanical analysis with an applied frequency of 1 Hz.

[0042] The graft rubber basis B1 can be produced by polymerizing the components B11 and optionally B12 in aqueous emulsion according to processes known to those skilled in the art generally at temperatures of 20°C to 100°C, preferably 50°C to 90°C and at pressures between 0 and 18, preferably 0 and 15 bar (gauge pressure). The polymerization may employ customary emulsifiers such as alkali metal salts of alkyl- or arylsulfonic acids, alkyl sulfates, fatty alcohol sulfonates, salts of higher fatty acids comprising 10 to 30 carbon atoms or resin soaps. It is preferable to employ the sodium or potassium salts of alkylsulfonates or fatty acids comprising 10 to 18 carbon atoms. The emulsifiers are favorably employed in an amount of 0.1 to 5 wt.-%, preferably 0.3 to 2 wt.-%, - based on the total weight of monomers forming B1 . A water / monomer weight ratio from 2:1 to 0.7:1 is generally employed.

[0043] Polymerization initiators employed are in particular the commonly used persulfates such as sodium or potassium peroxodisulfate, or mixtures thereof, though redox systems are also suitable. The amount of initiator is for example from 0.1 to 1 wt.-%, - based on the total weight of monomers forming B1.

[0044] Polymerization assistants that may be employed include customary buffer substances used to adjust the pH to the preferred range of 6 to 10, for example sodium bicarbonate, sodium carbonate and sodium pyrophosphate, or mixtures thereof and also generally 0.1 to 3 wt.-%, - based on the total weight of the monomers forming the graft rubber basis B1 -, of a molecular weight regulator such as mercaptan, e.g. tert.-dodecylmercaptan or n-dodecyclmercaptan, terpinol or dimeric a-methylstyrene. The molecular weight regulators can be added at once at the beginning of the polymerization or in several portions at the beginning and / or during the polymerization or continuously from the beginning until the end of the polymerization with constant or variable feed rates.

[0045] The feeding time for the components B11 and optionally B12 is preferably at least 6 hours, more preferably at least 7.5 hours and preferably less than 20 hours, more preferred less than 16 hours. The solids content in the aqueous dispersion after the polymerization is preferably from 25 to 50 wt.-%, particularly preferably from 30 to 48 wt.-%.

[0046] The graft rubber basis B1 is obtained in form of an aqueous dispersion of the graft rubber basis B1 particles. The precise polymerization conditions, in particular type, feed modus and amount of the emulsifier are preferably selected within the abovementioned ranges such that the graft rubber basis B1 has a weight median particle size Dso as defined herein below, as is described, for example, in DE102005022632, examples S11 to S13, or for example WO 2014 / 170406, examples A1 to A3.

[0047] Preferably, the graft rubber basis B1 particles have a gel content of more than 62%, more preferably more than 64%, even more preferably more than 66%. Preferably, the graft rubber basis B1 particles have a swelling index of less than 42, more preferably less than 40, even more preferably less than 38. In a preferred embodiment, the graft rubber basis B1 particles have a gel content of 90% or less, more preferably 85% or less and the swelling index is 15 or more, more preferably 20 or more. The gel content and swelling index values are generally determined with the wire cage method in toluene (see Houben-Weyl, Methoden der Organischen Chemie, Makromole- kulare Stoffe, part 1 , page 307 (1961) Thieme Verlag Stuttgart). A further detailed description of this method is disclosed in the experimental section.

[0048] It was found that with this gel content in combination with the given swelling index of the graft rubber basis B1 , improved surface qualities for the thermoplastic ABS molding composition, based on smaller emulsion particles, are achieved while balanced mechanical properties (e.g. impact resistance) are maintained. In particular, dull and gloss reduced, respectively, surfaces are avoided, even though when subjected to a shear rate typically observed in injection molding and extrusion.

[0049] The graft rubber basis B1 preferably has a weight median particle size Dso of not more than 150 nm, more preferably in the range of 50 to 150 nm, even more preferably in the range of 50 to 120 nm, even more preferably in the range of 80 to 120 nm, particularly preferably in the range of 80 to 110 nm.

[0050] The polydispersity II of the particle size distribution which is defined in this context as II = (D90 - Dio) / Dso of the graft rubber basis B1 is preferably less than 0.38, in particular less than 0.37. Preference is given to a graft rubber basis B1 having a weight median particle size D50 in the range of 80 to 120 nm and a polydispersity II of less than 0.38, in particular less than 0.37.

[0051] D10 and D90 values are defined as follows: Dm is the diameter at which 10 wt.-% of the particles are smaller than this value and D90 is the diameter at which 90 wt.-% of the particles are smaller than this value. Dm and D90 values can be determined using a disc centrifuge according to the method described herein above for the determination of the weight mean average particle diameter Dwand the weight median particle size D50.

[0052] Agglomeration agent

[0053] Agglomeration of the graft rubber base particles B1 in step (ii) of the process according to the invention is achieved by use of an agglomeration agent. Suitable agglomeration agents are such as acetic acid and acetic acid precursors, in particular acetic anhydride as acetic acid precursor, and preferably agglomerating copolymers (BC).

[0054] Agglomeration of the graft rubber basis B1 is preferably achieved by employing an agglomerating copolymer BC, a copolymer of (BC1) one or more hydrophobic comonomers selected from the group consisting of Ci to C12 alkyl acrylates, Ci to C12 alkyl methacrylates, and mixtures thereof, and (BC2) one or more hydrophilic comonomers selected from the group consisting of methacrylamide, acrylamide, methylacrylamide, ethylacrylamide, n-butylacrylamide, and mixtures thereof. The agglomerating component (BC) has preferably a weight median particle size Dso in the range of 100 to 150 nm.

[0055] Copolymer BC is generally comprising:

[0056] (BC1): 80 to 99.9 wt.-%, preferably 90 to 99.9 wt.-%, - based on the total weight of monomers forming BC -, and

[0057] (BC2): 0.1 to 20 wt.-%, preferably 0.1 to 10 wt.-%, - based on the total weight of monomers forming BC -, and where BC1 and BC2 sum to 100 wt.-%.

[0058] The monomers BC1 employed are preferably C1-C4 alkyl acrylates or mixtures thereof. The monomer BC1 is preferably ethyl acrylate. The monomer BC2 is preferably methacrylamide.

[0059] Preference is given to a copolymer BC comprising ethyl acrylate and methacrylamide. Particular preference is given to a copolymer BC comprising 92 to 98 wt.-%, - based on the total weight of monomers forming BC -, of ethyl acrylate and 2 to 8 wt.-%, - based on the total weight of monomers forming BC -, of methacrylamide. Very particular preference is given to a copolymer BC comprising 93 to 97 wt.-%, - based on the total weight of monomers forming BC -, of ethyl acrylate and 3 to 7 wt.-%, - based on the total weight of monomers forming BC -, of methacrylamide.

[0060] Particular preference is given to a copolymer BC described hereinabove and having a core comprising at least one of the hydrophobic monomers cited as component BC1 , preferably ethyl acrylate, wherein this core is covered with a copolymer comprising the components BC1 and BC2.

[0061] It is particularly preferable that the copolymer BC comprises:

[0062] (BC11): 5 to 20 wt.-%, - based on the total weight of monomers forming copolymer BC -, of one or more hydrophobic monomers (BC1), preferably ethyl acrylate, of a core (BC11), and

[0063] (BC12): 80 to 95 wt.-%, - based on the total weight of monomers forming copolymer BC -, of a sheath (BC12) polymerized in the presence of the core (BC11) and comprising:

[0064] (BC121): 93 to 97 wt.-%, - based on the total weight of monomers forming the sheath (BC12) -, of at least one hydrophobic monomer (BC1), preferably ethyl acrylate, and (BC122): 3 to 7 wt.-%, - based on the total weight of monomers forming the sheath (BC12) of at least one hydrophilic monomer (BC2), preferably methacrylamide.

[0065] It is very particularly preferable when the copolymer BC comprises:

[0066] (BC11): 8 to 12 wt.-%, - based on the total weight of monomers forming copolymer BC of ethyl acrylate, of a core (BC11), and

[0067] (BC12): 88 to 92 wt.-%, - based on the total weight of monomers forming copolymer BC of a sheath (BC12) polymerized in the presence of the core and comprising:

[0068] (BC121): 93 to 97 wt.-%, - based on the total weight of monomers forming the sheath BC12 -, of ethyl acrylate, and

[0069] (BC122): 3 to 7 wt.-%, - based on the total weight of monomers forming the sheath BC12 -, of methacrylamide.

[0070] Preference is accordingly given to a process for producing the agglomerating copolymer BC comprising monomer components BC1 and BC2, in particular ethyl acrylate and methacrylamide, said process comprising initially polymerizing a portion of BC1 , in particular ethyl acrylate, and subsequently adding the remaining portion of BC1 , in particular ethyl acrylate, and BC2, in particular methacrylamide, as a mixture. The portions correspond to the ratios described hereinabove.

[0071] The production of the agglomerating copolymer BC employed is carried out according to processes known to those skilled in the art, particularly advantageously by emulsion polymerization, and the emulsifiers cited hereinabove for the graft rubber basis B1 may be employed. It is preferable to employ the sodium and potassium salts of alkylsulfonates comprising 10 to 18 carbon atoms. The emulsifiers are advantageously employed in an amount of 0.5 to 5 wt.-%, preferably 0.5 to 2 wt.-%, based on the total weight of monomers forming copolymer BC.

[0072] Polymerization initiators employed are in particular the commonly used persulfates such as sodium or potassium peroxodisulfate, or mixtures thereof, though redox systems are also suitable. The amount of initiator is, for example 0.1 to 1 wt.-%, based on the total weight of monomers forming copolymer BC.

[0073] Polymerization assistants that may be employed include the customary buffer substances and / or basic substances used to adjust the pH to the preferred range of from 4 to 10. As buffer substances can be used for example sodium bicarbonate, sodium carbonate and sodium pyrophosphate, or mixtures thereof; as basic substances can be used for example sodium hydroxide, potassium hydroxide, or mixtures thereof. If desired molecular weight regulators such as mercaptan, e.g. tert.-dodecylmercaptan or n-dode- cy cl mercaptan, terpinol or dimeric a-methylstyrene can be used. The molecular weight regulators can be added at once at the beginning of the polymerization or in several portions at the beginning and / or during the polymerization or continuously from the beginning until the end of the polymerization with constant or variable feed rates.

[0074] The copolymer BC can be produced by aqueous emulsion polymerization according to processes known to those skilled in the art generally at temperatures of 20°C to 100°C, preferably 50°C to 90°C and at pressures between 0 and 6 bar, preferably 0 and 3 bar (gauge pressure). The solids content in the aqueous dispersion after the polymerization is preferably 3 to 70 wt.-%, more preferably from 5 to 60 wt.-%, particularly preferably from 7 to 50 wt.-%.

[0075] The process for producing the core / sheath copolymers BC described hereinabove is an emulsion polymerization preferably comprising (or consisting of) the steps of: (x) emulsion polymerizing at least one monomer BC1 as defined hereinabove in a first step and (y) adding a monomer mixture comprising (or consisting of) monomers (BC1+BC2) in a further step, wherein the steps (x) and (y) are performed in the presence of at least one emulsifier which is employed in an amount of 0.05 to 1.0 wt.-%, preferably 0.05 to 0.5 wt.-%, in step (x) and in an amount of 0.45 to 4.5 wt.-%, preferably 0.45 to 1.8 wt.-%, in step (y), in each case based on the total weight of monomers forming copolymer BC.

[0076] The copolymer BC is preferably employed as an aqueous dispersion, as a so-called agglomeration latex. The agglomerating copolymer BC can have different values of the polydispersity II of the particles size distribution, e.g. the particles size distribution can be broad with values of polydispersity II larger than 0.27 or narrow with a polydispersity II of 0.27 or less. Preferably the polydispersity II is broad and in the range of larger than 0.27. In another embodiment preferably the polydispersity II is narrow and in the range of 0.27 to 0.15, in particular in the range of 0.27 to 0.18.

[0077] The agglomerating copolymer BC preferably has a weight median particle size Dso in the range of 100 to 150 nm, more preferably 110 to 150 nm, most preferably 110 to 140 nm.

[0078] A preferred embodiment employs an agglomerating copolymer BC having a polydispersity II from 0.27 to 0.15, in particular from 0.27 to 0.18 and a weight median particle size Dso in the range of 110 to 150 nm, in particular 110 to 140 nm.

[0079] In the context of the present application, the abovementioned embodiments may be combined with one another. Agglomeration of the Graft Rubber Basis B1

[0080] In step (ii) of the process according to the invention the agglomeration of the graft rubber basis B1 - obtained in step (i) - is achieved by adding an agglomeration agent, preferably a dispersion of the copolymer BC described hereinabove. The concentration of the copolymer BC in the agueous dispersion used for agglomeration shall generally be between 3 to 70 wt.-%, more preferably from 5 to 60 wt.-%, particularly preferably from 7 to 50 wt.-%.

[0081] The agglomeration generally employs from 0.1 to 5 wt.-%, preferably from 0.5 to 4.5 wt- %, - based on the dry weight of the graft rubber basis B1 -, of the agglomeration agent.

[0082] The agglomeration is generally carried out at a temperature from 20°C to 100°C, preferably from 30°C to 90°C, more preferably from 30°C to 75°C and at pressures between 0 and 6, preferably 0 and 3 bar (gauge pressure).

[0083] The addition of the agglomeration agent, in particular copolymer BC, may be effected in one go or portion wise, continuously or with a feed profile over a particular time period. According to a preferred embodiment the addition of BC is effected such that 1 / 1 to 1 / 100 of the total weight of BC is introduced per minute. The agglomeration time, i.e. the time from the beginning of the addition of BC to the start of the subsequent graft copolymerization, is preferably from one minute to two or more hours, often one to four hours.

[0084] Basic electrolytes may optionally be added to the agglomeration process in an amount of 1 to 50 wt.-%, based on the dry weight of copolymer BC. Useful basic electrolytes include organic or inorganic hydroxides. Inorganic hydroxides especially are useful. Particular preference is given to using lithium hydroxide, sodium hydroxide or potassium hydroxide. According to one of the particularly preferred embodiments KOH is used as the basic electrolyte. According to another preferred embodiment NaOH is used as the basic electrolyte. However, it is also possible to employ mixtures of two or more basic electrolytes.

[0085] This may be advantageous, for example, when the growth of the rubber particles is to be precisely controlled. Hence, it may be useful, for example, to employ mixtures of LiOH with KOH or mixtures of LiOH with NaOH. It is likewise possible to use mixtures of KOH and NaOH and this constitutes a further preferred embodiment. The electrolytes are generally dissolved prior to addition. A preferred solvent is the aqueous phase. Preference is given to using diluted solutions, for example solutions having a concentration in the range of 0.001 to 0.1 , in particular from 0.001 to 0.05, preferably less than 0.03, for example less than 0.025, each referring to g of basic electrolyte / mL of solvent. The addition of the basic electrolytes may be effected prior to the addition of copolymer BC, simultaneously therewith or separately therefrom or after addition of B1.

[0086] It is also possible to premix the basic electrolytes in the dispersion of BC. According to a preferred embodiment the addition of the basic electrolytes is effected prior to the addition of the agglomeration copolymer BC. The basic electrolyte is generally employed in an amount in the range of 0.01 to 4 wt.-%, preferably 0.05 to 2.5 wt.-%, in particular 0.1 to 1 .5 wt.-%, - based on the dry weight of component B.

[0087] The pH during the agglomeration is generally from 6 to 13. According to a preferred embodiment of the invention, the pH is from 8 to 13.

[0088] Agglomerated Graft Rubber Basis B1

[0089] Generally, only a fraction of the particles in the latex of the graft rubber basis B1 is agglomerated to larger particles.

[0090] The agglomeration yield is the fraction y) of the agglomerated particles in wt.-% based on the total weight of the particles. The agglomeration yield is determined from the cumulative distribution curve of the particle size measurement.

[0091] The agglomerated graft rubber basis B1 obtained after the agglomeration has preferably a weight-based, bimodal particle size distribution of fractions x) and y) where x) is a fraction of non-agglomerated particles and y) is a fraction of agglomerated particles having a weight median particle size Dso in the range of 300 to 650 nm. The non-agglomer- ated particles of the fraction x) generally have a weight median particle size Dso of not more than 150 nm, preferably in the range of 80 to 120 nm.

[0092] The agglomerated graft rubber basis B1 preferably comprises a fraction y) of agglomerated particles having a weight median particle size Dso in the range of 300 to 550 nm, particularly preferably 310 to 480 nm.

[0093] The weight fraction of the particles of the fraction x) of the agglomerated graft rubber basis B1 is generally 15 to 40 wt.-%, preferably 20 to 35 wt.-%, and the weight fraction of the particles of the fraction y) is generally 60 to 85 wt.-%, preferably 65 to 80 wt.-%, - based on the total weight of the particles -, x) and y) generally sum to 100 wt.-%.

[0094] According to one embodiment, the invention relates to a process for the preparation of a graft copolymer B according to the invention, wherein agglomerating copolymer (BC) comprises: (BC1): 80 to 99.9 wt.-% of ethyl acrylate, - based on the total weight of monomers forming BC and

[0095] (BC2): 0.1 to 20 wt.-% of methacrylamide, - based on the total weight of monomers forming BC -, where (BC1) and (BC2) sum to 100 wt.-%, and where the agglomerating copolymer (BC) has a weight median particle size Dso of 100 to 150 nm, preferably 110 to 150 nm, and a polydispersity II larger than 0.27 or of 0.27 or less, preferably less than 0.27, preferably in the range of 0.27 to 0.15, and the agglomerated graft rubber basis B1 has a weight-based, bimodal particle size distribution of a fraction x) of non-agglomerated particles in an amount of 15 to 40 wt.-%, - based on the total weight of all particles -, having a weight median particle size Dso of not more than 150 nm, preferably in the range of 80 to 120 nm and a fraction y) of agglomerated particles in an amount of 60 to 85 wt.-%, - based on the total weight of all particles -, having a weight median particle size Dso in the range of 300 to 650 nm, preferably 300 to 550 nm.

[0096] The obtained dispersion of the agglomerated graft rubber basis B1 is relatively stable and may be readily stored and transported without onset of visible coagulation. In the process according to the invention the agglomerated graft rubber basis B1 is used to produce graft copolymer B.

[0097] Graft Copolymer B

[0098] In (graft polymerization) step (iii) of the process according to the invention - copolymerization of components B21 , B22, and optionally B23 in presence of the agglomerated graft rubber basis B1 (obtained in step (ii)) - at least one polymerization initiator is fed in at least two, preferably two, portions, whereof a first portion of the initiator is fed before feeding and copolymerizing components B21 , B22, and optionally B23 forming the one or more graft sheaths B2 to obtain graft copolymer B.

[0099] The second initiator portion (or further initiator portion) is generally added after the addition of components B21 , B22, and optionally B23 is completed.

[0100] Preferably, component B23 is not present.

[0101] Component B preferably comprises 40 to 85 wt.-%, - based on the dry weight of component B -, of the graft rubber basis (B1) and preferably 15 to 60 wt.-%, - based on the dry weight of component B -, of one or more graft sheaths B2 (component B2). B1 and B2 sum to 100 wt.-%. Component B2 (forming part of graft copolymer B = component B) may be preferably obtained by polymerization of 70 to 90 wt.-%, more preferably 75 to 85 wt.-%, styrene and / or a-methylstyrene (B21), in particular styrene, - based on the total weight of monomers forming B2 and 10 to 30 wt.-%, more preferably 15 to 25 wt.-%, of acrylonitrile and / or methacrylonitrile (B22), in particular acrylonitrile, - based on the total weight of monomers forming B2 -, in the presence of the agglomerated graft rubber basis B1 (obtained in step (ii)). Components B21 and B22 sum to 100 wt.-%.

[0102] Preferred components B2 are comprising copolymers of styrene and acrylonitrile, and / or copolymers of a-methylstyrene and acrylonitrile. Particular preference is given to copolymers of styrene and acrylonitrile. Particularly preferred components B2 are obtained by reaction of 75 to 85 wt.-% of styrene (B21) and 15 to 25 wt.-% of acrylonitrile (B22) - based on the total weight of monomers forming B2. Components B21 and B22 sum to 100 wt.-%.

[0103] Preferably, the graft polymerization in step (iii) of the process according to the invention is performed as an emulsion polymerization. In step (iii) of the process according to the invention component B2 (forming part of graft copolymer B = component B) is preferably prepared by an emulsion polymerization process in presence of the agglomerated graft rubber basis B1 (obtained in step (ii)).

[0104] The graft copolymerization - in step (iii) of the process according to the invention - for preparing component B2 may be performed in the same polymerization system as the emulsion polymerization for producing the graft rubber basis B1 and further emulsifiers and assistants may be added if necessary. This means that the graft rubber basis B1 may be used after the agglomeration without further work-up either in the same or a different polymerization reactor and further emulsifiers and assistants may optionally be added.

[0105] The graft polymerization step (iii) of the process according to the invention is preferably performed in aqueous emulsion at temperatures of 20°C to 100°C, preferably 50°C to 90°C, and at pressures between 0 and 18 bar(g), preferably 0 and 15 bar(g) (gauge pressure).

[0106] According to the invention, at least one of the process conditions a) and / or b) in combination with process condition c) is applied in the process step (iii).

[0107] In case process condition a) is applied in step (iii) of the process according to the invention, the polymerization temperature is preferably controlled in a way that the feeding of (monomer) components B21 , B22 and optionally B23 is started at a temperature of 62 to 72°C, preferred 64 to 72°C, and - during the feeding of B21 , B22 and optionally B23 - the temperature is increased within a time period of 1 hour and 45 minutes or less, often within a time period of 1 hour and 45 minutes to 1 hour and 20 minutes, more often within a time period of 1 hour and 35 minutes to 1 hour and 20 minutes (for example in about 1 hour and 35 minutes, in about 1 hour and 30 minutes, in about 1 hour and 25 minutes, in about 1 hour and 23 minutes), very often within a time period of 1 hour and 30 minutes to 1 hour and 20 minutes, from the start (feeding) temperature to a temperature of at least 10°C higher than the start. This often leads to an end temperature of 79°C to 81 °C. The time period from the start (feeding) temperature to a temperature of at least 10°C higher than the start is also called heating ramp time period according to the invention.

[0108] The time period for the feeding of (monomer) components B21 , B22 and optionally B23 may differ from the heating ramp time period or may be identical to the heating ramp time period. Often, the heating ramp time period is identical or shorter than the time period for the feeding of (monomer) components B21 , B22 and optionally B23.

[0109] The components B21 , B22 and optionally B23, preferably B21 and B22 (in particular styrene and acrylonitrile), may be added to the reactor individually or preferably as a mixture. Accordingly, each component B21 , B22 and optionally B23 may be added via a separate feed or at least two of the components B21 , B22 and optionally B23 may be added to the reactor as a mixture via a single feed.

[0110] The components B21 , B22 and optionally B23, preferably B21 and B22 (in particular styrene and acrylonitrile), may be added to the reactor simultaneously or at least partly separately. Accordingly, each component B21 , B22 and optionally B23 may be added simultaneously, i.e. during substantially the same time period, or at least one of the components B21 , B22 and optionally B23 at least partly may be added without feeding the other components at the same time period.

[0111] In accordance with one embodiment, in step (iii) of the process according to the invention, the component B2 is prepared by adding component B21 without B22 (and optionally B23) in an optional first step, followed by a second step, in which components B21 , B22 (and optionally B23) are added simultaneously.

[0112] The addition of components B21 , B22, and optionally B23, preferably B21 and B22 (in particular styrene and acrylonitrile) to the reactor may be carried out in a continuous fashion or spread over a plurality of stages, for example to construct a plurality of graft sheaths. The components B21 , B22 and optionally B23, preferably B21 and B22 (in particular styrene and acrylonitrile), may be added simultaneously with constant feed rates ^constant ratio of the feed rates of B21 , B22 and optionally B23) or with variable feed rates (=variable ratios of the feed rates of B21 , B22 and optionally B23), according to the teaching of the application WO 2015 / 165810 A1.

[0113] According to step (iii) of the process of the invention, the polymerization initiator is applied in at least in two portions, preferably two portions. Preferred is to use two portions of polymerization initiator feeds, preferably the first portion being always larger than the second portion.

[0114] In case process condition b) is applied to step (iii) of the process according to the invention - the first portion of the initiator is at least 52 % by weight, preferred at least 55 % by weight, more preferred at least 60 % by weight of the total initiator amount applied in grafting step (iii).

[0115] The polymerization initiator applied in grafting step (iii) is preferably provided as an aqueous solution.

[0116] Particulars pertaining to the performance of the graft polymerization are known to those skilled in the art and are disclosed, for example, in DE-A 2427960, EP-A 0062901 or WO 2014 / 170406 (see “Pfropfcopolymer B, Allgemeine Vorgehensweise”, pp 34-35).

[0117] The polymerization in step (iii) may employ the customary emulsifiers such as alkali metal salts of alkyl- or arylsulfonic acids, alkyl sulfates, fatty alcohol sulfonates, salts of higher fatty acids comprising 10 to 30 carbon atoms or resin soaps. It is preferable to employ the sodium or potassium salts of alkylsulfonates or fatty acids comprising 10 to 18 carbon atoms. The emulsifiers are favorably employed in an amount of from 0.1 to 3 wt.-%, preferably from 0.15 to 1 wt.-%, - based on the dry weight of component B.

[0118] Polymerization initiators employed in step (iii) are in particular the commonly used persulfates such as sodium or potassium peroxodisulfate, or mixtures thereof, though redox systems are also suitable. Preferably, the polymerization initiators employed in step (iii) are selected from sodium peroxodisulfate, potassium peroxodisulfate, and mixtures thereof. The amounts of initiators are for example 0.02 to 1 wt.-%, based on the dry weight of component B.

[0119] Polymerization assistants that may be employed in the process according to the invention include the customary buffer substances used to adjust the pH to the preferred range of 6 to 10, for example sodium bicarbonate, sodium carbonate and sodium pyrophosphate, or mixtures thereof.

[0120] No molecular weight regulators or chain transfer agents are used in the graft polymerization step (iii) (=process condition c)).

[0121] According to one embodiment, at least the process condition a) is applied in combination with process condition c) in process step (iii).

[0122] According to one embodiment, at least the process condition b) is applied in combination with process condition c) in process step (iii).

[0123] According to one embodiment, the process conditions a) and b) are applied in combination with process condition c) in process step (iii).

[0124] Preferably, in the process according to the invention, process steps (i) and (iii) are performed in an aqueous emulsion.

[0125] According to a further - less preferred - embodiment, in step iii) of the process according to the invention, process conditions a) and / or b) and / or c) may be combined with a further process condition d) wherein a minimal feed time of 180 minutes, often of at least 195 minutes, or often 205 to 230 minutes, for feeding monomer components B21 , B22, and optionally B23, preferably B21 and B22, is applied. Said feed times may be advantageous in order to improve further the gloss and the gloss stability of ABS molding compositions comprising graft copolymer B. In the interest of improved cycle times during the production process this embodiment (encompassing further process condition d)) is less preferred.

[0126] The solids content in the aqueous dispersion after the graft polymerization is preferably from 25 to 50 wt.-%, particularly preferably from 30 to 45 wt.-%, based on the total weight of the aqueous dispersion.

[0127] Preferably, the particles of component B have a weight-based, bimodal particle size distribution and the graft rubber basis B1 comprises 79 to 100 wt.-%, preferably 80 to 99 wt.-% butadiene (B11) and 0 to 21 wt.-%, preferably 1 to 20 wt.-%, - based on the total weight of monomers forming B1 -, of at least one further monomer (B12) selected from the group consisting of: styrene, a-methylstyrene, acrylonitrile, methacrylonitrile, methyl methacrylate, maleic acid anhydride, and N-phenylmaleimide, preferably styrene, where B11 and B12 sum to 100 wt.-%.

[0128] Preferably, the graft copolymer B is present in form of particles having a weight mean average particle diameter Dw in the range of 50 to 950 nm, in particular 80 to 600 nm. According to one embodiment, the invention relates to a process for the preparation of a graft copolymer B according to the invention, wherein graft copolymer B comprises 40 to 85 wt.-% of the graft rubber basis (B1) and 15 to 60 wt.-% of one or more graft sheaths B2 (component B2), - each based on the dry weight of B -, and where the graft rubber basis B1 comprises:

[0129] B11 : 79 to 100 wt.-% butadiene and / or isoprene, preferably butadiene, - based on the total weight of monomers forming B1 -, and

[0130] B12: 0 to 21 wt.-% a-methylstyrene and / or styrene, preferably styrene, - based on the total weight of monomers forming B1 -, where B11 and B12 sum to 100 wt.-%, and where the graft sheath B2 comprises:

[0131] (B21) 70 to 90 wt.-% of styrene and / or a-methylstyrene, in particular styrene, - based on the total weight of monomers forming B2 -, and

[0132] (B22) 10 to 30 wt.-% of acrylonitrile and / or methacrylonitrile, in particular acrylonitrile, - based on the total weight of monomers forming B2 -, wherein component (B23) is not present, and where (B21) and (B22) sum to 100 wt.-%, and where components B1 and B2 sum to 100 wt.-%.

[0133] In accordance to the process according to the invention, the particulate graft rubber basis B1 (i.e. the graft rubber basis B1 particles), in particular obtained in step i), preferably has a weight median particle size Dso of not more than 150 nm, preferably in the range of 50 to 150 nm, more preferably 50 to 120 nm.

[0134] Preferably, in step (ii) of the process according to the invention an agglomerating copolymer (BC) is used as the agglomeration agent and comprises:

[0135] (BC1): 80 to 99.9 wt.-% of ethyl acrylate, - based on the total weight of monomers forming BC -, and

[0136] (BC2): 0.1 to 20 wt.-% of methacrylamide, - based on the total weight of monomers forming BC -, where (BC1) and (BC2) sum to 100 wt.-%.

[0137] Preference is given to a process according to the invention wherein graft copolymer B (component B) comprises:

[0138] B1 : 40 to 85 wt.-%, - based on the dry weight of B -, of at least one graft rubber basis B1 comprising:

[0139] B11 : 79 to 100 wt.-% of butadiene, - based on the total weight of monomers forming B1 -, and B12: 0 to 21 wt.-% of styrene, - based on the total weight of monomers forming B1 , where B11 and B12 sum to 100 wt.-%;

[0140] B2: 15 to 60 wt.-%, - based on the dry weight of B of one or more graft sheaths B2 comprising:

[0141] B21 : 70 to 90 wt.-% of styrene, - based on the total weight of monomers forming B2 -, and

[0142] B22: 10 to 30 wt.-% of acrylonitrile, - based on the total weight of monomers forming B2, where B21 and B22 sum to 100 wt.-%, and where components B1 and B2 sum to 100 wt.-%, and wherein steps (i) and (iii) are performed in an aqueous emulsion; and where in step (ii) 0.1 to 5 wt.-%, - based on the dry weight of graft rubber basis B1 -, of an agglomerating copolymer (BC) is used as the agglomeration agent which comprises:

[0143] (BC1): 80 to 99.9 wt.-% of ethyl acrylate, based on the total weight of monomers forming BC, and

[0144] (BC2): 0.1 to 20 wt.-% of methacrylamide, based on the total weight of monomers forming BC, where (BC1) and (BC2) sum to 100 wt.-%, and where the agglomerating copolymer (BC) has a weight median particle size Dso in the range of 100 to 150 nm, preferably 110 to 150 nm, and a polydispersity II larger than 0.27 or of 0.27 or less, preferably less than 0.27, preferably in the range of 0.27 to 0.15, and the agglomerated graft rubber basis B1 (obtained in step (ii)) has a weight-based, bi- modal particle size distribution of fractions x) and y) where x) is fraction of non-agglom- erated particles in an amount of 15 to 40 wt.-%, preferably 20 to 35 wt.-%, - based on the total weight of all particles -, having a weight median particle size Dso of not more than 150 nm, preferably in the range of 80 to 120 nm, and y) is a fraction of agglomerated particles in an amount of 60 to 85 wt.-%, preferably 65 to 80 wt.-%, - based on the total weight of all particles -, having a weight median particle size Dso in the range of 300 to 550 nm, preferably 310 to 480 nm, where x) and y) sum to 100 wt.-%.

[0145] Graft copolymer B (component B) obtained in step (iii) of the process according to the invention may be used as obtained in the reaction mixture, for example as a latex emulsion or latex dispersion. Alternatively, however, graft copolymer B may also be worked up in a further optional process step (iv). A stabilizer dispersion can be added to the component B before the workup process takes place.

[0146] Workup process conditions are known in principle to those skilled in the art. In an optional process step (iv) graft copolymer B (component B) may be isolated from the reaction mixture, for example by spray drying, shearing or by precipitation with strong acids or using other precipitants, for example inorganic salts such as magnesium sulfate.

[0147] The solids content of the dispersion of component B is preferably about 40 wt.-%.

[0148] Preferably, in said optional further process step (iv) of the process according to the invention, component B is isolated, preferably precipitated, from the reaction mixture, in particular in an aqueous precipitation step (iv), wherein the aqueous composition used for precipitation contains less than 7.0 wt.-%, more preferred less than 4.0 wt.-%, even more preferred less than 3.5 wt.-%, for example 2.5 wt.-%, of salt(s), based on the dry weight of component B.

[0149] In general, the precipitation of component B (in a dispersion of about 20 wt.-% B in water, e.g. 18 to 22 %) is feasible with a bi-valent salt (in a concentration between 0.3 and 0.7 wt.-% in water in the precipitation vessel, which corresponds to between 1.5 % and 3.5 wt.-% of salt, based on the dry weight of component B). Concentrations below these values can be applied e.g. for tri-valent salts.

[0150] In a further embodiment, the aqueous composition for precipitation comprises about 20 wt.-% solids content (e.g. 18 to 22 %), wherein the solid is component B, and about 0.8 wt.-% of salt, what corresponds to 4 wt.-% of salt, based on the dry weight of the component B, in a dispersion with 20 wt.-% of solids content.

[0151] Preferably, the salt used for the precipitation step is chosen from a group comprising anhydrous magnesium sulfate, magnesium sulfate with crystal water, anhydrous aluminium sulfate, aluminium sulfate with crystal water, calcium chloride, magnesium chloride, magnesium hydroxide and bi-valent salts and tri-valent salts, in particular magnesium and calcium, with sulphuric acid and combinations thereof.

[0152] The isolation step (iv), in particular aqueous precipitation step (iv), is often directly or indirectly followed by a sintering step (v), wherein the precipitated component B is agglomerated to larger particles, characterized by using a temperature from 100° to 125 °C, preferred below 120 °C, more preferred below 115 °C and in other cases from 100° to 110 °C. In particular, the sintering step is effectuated at a pressure above atmospheric pressure. Component B can be treated in one or more sintering steps. In general, the residence time for the sintering step is 180 minutes or less, preferably less than 60 min and more preferably from 30 to 40 minutes. The total residence time for the isolation step (iv), in particular precipitation step (iv), and the sintering step (v) is preferably between 45 and 90 minutes, in particular about 60 minutes. In the precipitation step (iv) as well as in the sintering step (v), the water contains preferably between 15 wt.-% to 25 wt.-%, more preferably 18 wt.-% to 22 wt.-% of solid components. In a preferred embodiment, in an optional further step (vi) of the process according to the invention, component B is washed directly or indirectly after the sintering step (v) with an amount of water, which corresponds to 1 to 90 wt.-%, more preferred 10 to 50 wt.-% of water, based on the dry weight of component B. In a preferred embodiment, component B is washed with water after the sintering step (v) and during and / or after an optional centrifugation step (vii), whereas the amount of washing water is > 1 wt.-%, preferred >5 wt.-%, especially preferred >10 wt.-% based on the dry weight of component B.

[0153] After the sintering step, the sintered component B is often treated in a further step (vii) to remove some of the water. Partial dewatering may be achieved, for example, by filtration, settling out, pressing out, decanting, centrifugation or thermal drying. Preferably, one or more centrifugation steps are used. Component B is preferably partially dewatered to a residual water content of up to 60 wt.-%, often up to 40 wt.-%.

[0154] For further use in a molding composition the obtained component B having a residual water content of up to 60 wt.-%, often up to 40 wt.-%, may be fed to an extruder, often to the first feeding zone FZ1 of an extruder.

[0155] A further aspect of the invention is a graft copolymer B obtained by the process according to the invention.

[0156] Thermoplastic ABS molding composition

[0157] The invention further relates to a thermoplastic ABS molding composition, comprising (or consisting of) at least one graft copolymer B obtained by the process according to the invention, at least one (rubber-free) styrenic copolymer matrix A, one or more additives D, and optionally one or more thermoplastic polymers C selected from the group consisting of polycarbonates, polyesters, polyester carbonates and polyamides.

[0158] Preferably, the thermoplastic ABS molding composition according to the invention comprises (or consists of):

[0159] A: 39.99 to 80 wt.-%, preferably 42.95 to 79 wt.-%, more preferably 43.90 to 75 wt- %, - based on the total weight of the molding composition -, of at least one (rubber- free) styrenic copolymer matrix A (component A) comprising:

[0160] A11 : 60 to 80 wt.-%, preferably 69 to 80 wt.-%, - based on the total weight of A -, of styrene and / or a-methylstyrene and / or p-methyl-styrene (component A11), preferably styrene; and A12: 20 to 40 wt.-%, preferably 20 to 31 wt.-%, - based on the total weight of A of (meth)acrylonitrile (component A12), preferably acrylonitrile;

[0161] A13: 0 to 20 wt.-%, preferably 0 to 11 wt.-%, of one or more co-polymerizable monomers (component A13), preferably Ci-Cs-acrylates and / or methyl methacrylate, - based on the total weight of A; where the components A11 , A12 and, if present, A13 sum to 100 wt.-%.

[0162] B: 19.99 to 60 wt.-%, preferably 20.95 to 57 wt.-%, more preferably 24.90 to 56 wt- %, - based on the total weight of the molding composition -, of at least one graft copolymer B obtained by the process according to the invention;

[0163] C: 0 to 40 wt.-%, preferably 0 to 30 wt.-%, more preferably 0 to 20 wt.-%, - based on the total weight of the molding composition -, of at least one further thermoplastic polymer C, preferably selected from the group consisting of polycarbonates, polyesters, polyester carbonates and polyamides (component C);

[0164] D: 0.01 to 20 wt.-%, preferably 0.05 to 5 wt.-%, more preferably 0.10 to 5 wt.-%, - based on the total weight of the molding composition -, of one or more additives D (component D), in particular selected from the group consisting of: stabilizers, dispersants, pigments, lubricants, dyes, colorants, inorganic fillers, organic fillers, antistatic agents, flame retardants, antidrip agents and matting agents; where the components A, B, D and, if present, C sum to 100 wt.-%.

[0165] More preferably, the thermoplastic ABS molding composition according to the invention comprises (or consists of):

[0166] A: 39.99 to 80 wt.-%, preferably 42.95 to 79 wt.-%, more preferably 43.90 to 75 wt- %, - based on the total weight of the molding composition -, of at least one (rubber- free) styrenic copolymer matrix A comprising:

[0167] A11 : 69 to 80 wt.-%, - based on the total weight of A -, of styrene or a-me- thylstyrene, or a mixture of styrene and a-methylstyrene; and

[0168] A12: 20 to 31 wt.-%, - based on the total weight of A -, of acrylonitrile; where the components A11 and A12 sum to 100 wt.-%.

[0169] B: 19.99 to 60 wt.-%, preferably 20.95 to 57 wt.-%, more preferably 24.90 to 56 wt- %, - based on the total weight of the molding composition of at least one graft copolymer B obtained by the process according to the invention, C: 0 to 40 wt.-%, preferably 0 to 30 wt.-%, more preferably 0 to 20 wt.-%, - based on the total weight of the molding composition of one or more thermoplastic polymers C selected from the group consisting of: polycarbonates, polyesters, polyester carbonates and polyamides;

[0170] D: 0.01 to 20 wt.- %, preferably 0.05 to 5 wt.-%, more preferably 0.10 to 5 wt.-%, - based on the total weight of the molding composition -, of one or more additives D, in particular selected from the group consisting of: stabilizers, dispersants, pigments, lubricants, dyes, colorants, inorganic fillers, organic fillers, antistatic agents, flame retardants, antidrip agents and matting agents, where the components A, B, D and, if present, C sum to 100 wt.-%.

[0171] The gloss of the molding composition according to the invention is determined in accordance with DIN 67530:1982-01 at an angle of 20°.

[0172] The molding composition according to the invention has a gloss ratio - non-optimal injection molding conditions (methods Y and Z) to good injection molding conditions (method X) - of at least 80%, preferably of at least 85%, more preferably at least 90%.

[0173] A gloss ratio of at least 80% indicates a good gloss stability under different injection molding conditions which is due to the used graft copolymer B obtained by the process according to the invention where in step (iii) the specific process conditions a) and / or b) in combination with c) are applied.

[0174] Method X: To determine the gloss characteristics for good injection molding conditions X, rectangular platelets are produced from the polymer melt using an injection molding machine at a compound temperature of 250°C and a mold temperature of 80°C.

[0175] Method Y: To determine the gloss characteristics for non-optimal injection molding conditions Y, rectangular platelets are produced from the polymer melt using an injection molding machine at a compound temperature of 250°C and a mold temperature of 50°C.

[0176] Method Z: To determine the gloss characteristics for non-optimal injection molding conditions Z, rectangular platelets are produced from the polymer melt using an injection molding machine at a compound temperature of 250°C and a mold temperature of 40°C.

[0177] The afore-mentioned rectangular platelets used in method X, Y or Z have the same dimensions. Commonly said rectangular platelets have dimensions in the range of 60 mm x 40 mm x 2 mm to 75 mm x 50 mm x 2 mm, often 75 mm x 50 mm x 2 mm. The gloss ratio is determined by the following formula:

[0178] ( 20° gloss method Y + 20° gloss method Z ) 100 [%]

[0179] The obtained (gloss ratio) value describes the gloss stability at different injection molding conditions. The higher the value, the more uniform the gloss performance.

[0180] In addition to the previously mentioned gloss characteristics, the molding composition according to the invention has good mechanical and optical properties such as good Charpy notched impact strength, good flowability (MVR), good Vicat softening temperature, and good (low) yellowness index. This means that the mechanical and optical properties are substantially not deteriorated compared to molding compositions not prepared in accordance with the invention. Also, the content of volatile organic compounds such as residual monomers or impurities such as vinyl cyclohexene is not substantially deteriorated. Methods to determine these properties are described in the experimental section.

[0181] Copolymer Matrix A

[0182] The thermoplastic ABS molding composition according to the invention comprises at least one (rubber-free) styrenic copolymer matrix A (component A) comprising component A11 , component A12 and optionally component A13, wherein the components A11 , A12 and, if present A13, sum to 100 wt.-%.

[0183] Preferably component A13 is not present as component of copolymer matrix A.

[0184] Component A forms the matrix of the thermoplastic ABS molding composition and is preferably comprising the components acrylonitrile and styrene and / or a-methylstyrene, polymerized by bulk polymerization or in the presence of one or more solvents. Preference is given to component A having weight average molar masses Mw of from 50,000 to 300,000 g / mol. The number-averaged molar mass (Mn) of component A is preferably from 15,000 to 100,000 g / mol.

[0185] The weight average molar masses (Mw) and the number-average molar masses (Mn) may be determined, for example, by means of gel permeation chromatography (polystyrene standard) with tetrahydrofuran as solvent and with UV detection. The viscosity of component A (determined according to DIN 53726:1983-09 at 25 °C in a 0.5 wt.-% solution in DMF) is, for example, from 50 to 120 mL / g.

[0186] Component A may in particular comprise or consist of:

[0187] (Aa) polystyrene-acrylonitrile, comprising, - based on the total weight of (Aa) -, 69 to 80 wt.-% of styrene (A11) and 20 to 31 wt.-% of acrylonitrile (A12), where (A11) and (A12) sum to 100 wt.-%, or

[0188] (Ab) poly-a-methylstyrene-acrylonitrile, comprising, - based on the total weight of (Ab) -, 69 to 80 wt.-% of a-methylstyrene (A11) and 20 to 31 wt.-% of acrylonitrile (A12), where (A11) and (A12) sum to 100 wt.-%, or

[0189] (Ac) a mixture of the copolymer matrix (Aa) and the copolymer matrix (Ab).

[0190] Component A may also be obtained by copolymerization of acrylonitrile, styrene and a- methylstyrene. However, it is also possible in principle to employ polymer matrices containing further monomer building blocks.

[0191] Component A may be produced by bulk polymerization / solution polymerization in, for example, toluene or ethylbenzene according to a process such as is described, for example, in Kunststoff-Handbuch, Vieweg-Daumiller, Vol. V, (Polystyrol), Carl-Hanser-Ver- lag, Munich 1969, pages 122 f., lines 12 ff.

[0192] As previously described hereinabove component A is preferably polystyrene-acrylonitrile, poly-a-methylstyrene-acrylonitrile or mixtures thereof.

[0193] Thermoplastic polymer C

[0194] Further, the thermoplastic ABS molding composition can additionally comprise one or more further thermoplastic polymers C selected from the group of polycarbonates, polyester carbonates, polyesters and polyamides. Suitable examples include, in particular, semicrystalline polyamides, semiaromatic copolyamides, polyesters, and / or polycarbonates.

[0195] Suitable polycarbonates are known per se. They are obtainable by interfacial polycondensation, for example by the processes of DE-B-1 300266, or by reacting diphenyl carbonate with bisphenols according to the process of DE-A-1495730.

[0196] Suitable polyamides are known homopolyamides, copolyamides and mixtures of such polyamides. They may be semi-crystalline and / or amorphous polyamides. Preferred polyamides are very generally those having an aliphatic semicrystalline or partly aromatic and amorphous structure of any type, and blends thereof. Appropriate products are available, for example, under the trade name Ultramid® (RTM) obtainable from BASF. Suitable semi-crystalline polyamides are polyamide-6, polyamide-6,6, mixtures thereof and corresponding copolymers of those components.

[0197] Suitable, in particular thermoplastic, polyesters are preferably polyalkylene terephthalates, that is to say reaction products of aromatic dicarboxylic acids or reactive derivatives thereof (e.g. dimethyl esters or anhydrides) and aliphatic, cycloaliphatic or arylaliphatic diols, and mixtures of such reaction products. Preferred polyalkylene terephthalates may be prepared from terephthalic acids (or reactive derivatives thereof) and aliphatic or cycloaliphatic diols having from 2 to 10 carbon atoms according to known methods (Kunststoff-Handbuch, Volume VIII, p. 695 ff, Carl Hanser Verlag, Munich 1973).

[0198] It is also possible to employ mixtures of two or more of the cited polymers C. The thermoplastic ABS molding composition may comprise, - based on the total weight of the thermoplastic ABS molding composition -, from 0 to 40 wt.-%, preferably 0 to 30 wt.-%, particularly preferably 0 to 20 wt.-%, of the abovementioned thermoplastic polymers C, also referred to as component C.

[0199] If component C is present, its minimum amount is 0.1 wt.-%, - based on the total weight of the thermoplastic ABS molding composition.

[0200] Preference is given to a thermoplastic ABS molding composition according to the invention consisting of component A, component B, component D and optionally component C.

[0201] Additives D

[0202] As additives D, the thermoplastic molding compound may comprise in particular one or more components selected from the group consisting of: stabilizers, dispersants, pigments, lubricants, dyes, colorants, inorganic fillers, organic fillers, antistatic agents, flame retardants, antidrip agents and matting agents.

[0203] Various additives, as or comprised in component D, may be added to the thermoplastic ABS molding composition in amounts in the range of 0.01 to 20 wt.-%, preferably 0.05 to 5 wt.-%, - based on the total weight of the thermoplastic ABS molding composition -, as assistants and processing additives. Suitable additives include all substances customarily employed for processing or finishing the polymers. Examples for component D include dyes, pigments, lubricants, colorants, antistatic agents, stabilizers - such as antioxidants, stabilizers for improving thermal stability, stabilizers for increasing photostability (= light stabilizers), stabilizers for enhancing hydrolysis resistance and chemical resistance, anti-thermal decomposition agents -, and in particular lubricants that are useful for production of molded bodies / articles. These additives may be in part admixed at any stage of the manufacturing operation, but preferably at an early stage in order to profit early on from the stabilizing effects (or other specific effects) of the additives. For further customary assistants and added substances, see, for example, “Plastics Additives Handbook”, Hans Zweifel, 6th Edition, Hanser Publ., Munich, 2009.

[0204] Inorganic fillers and / or organic fillers, preferably include fibrous or particulate fillers or mixtures thereof, and are optionally present in amounts of 0.01 to 5 wt.-%, - in each case based on the total weight of the thermoplastic ABS molding composition. Examples of inorganic fillers (or reinforcers) that may be employed include glass fibers that may be finished with a sizing and a coupling agent, glass beads, mineral fibers, aluminum oxide fibers, mica, quartz flour or wollastonite. It is also possible to admix with the thermoplastic ABS molding composition metal flakes, metal powder, metal fibers, metal-coated fillers, for example nickel-coated glass fibers, and other additive substances that shield electromagnetic waves. It is also possible to add carbon fibers, carbon black, in particular conductivity carbon black, or nickel-coated carbon fibers.

[0205] Examples of fibrous / pulverulent fillers include carbon or glass fibers in the form of glass fabrics, glass mats, or filament glass rovings, chopped glass, glass beads, and wollastonite, particular preference being given to glass fibers. When glass fibers are used they may be finished with a sizing and a coupling agent to improve compatibility with the blend components. The glass fibers incorporated may either take the form of short glass fibers or else continuous filaments (rovings).

[0206] Examples of suitable particulate fillers include carbon black, amorphous silica, magnesium carbonate, powdered quartz, mica, bentonites, talc, feldspar or, in particular, calcium silicates, such as wollastonite, and kaolin.

[0207] Examples of suitable pigments include titanium dioxide, phthalocyanines, ultramarine blue, iron oxides or carbon black, and the entire class of organic pigments.

[0208] Examples of suitable colorants include all dyes that may be used for transparent, semitransparent, or non-transparent coloring of polymers, in particular those suitable for coloring styrene copolymers. Examples of suitable flame retardants that may be used include the halogen-containing or phosphorus-containing compounds known to the person skilled in the art, magnesium hydroxide, and also other commonly used compounds, or mixtures thereof.

[0209] Examples of suitable antioxidants include sterically hindered monocyclic or polycyclic phenolic antioxidants, which may comprise various substitutions and may also be bridged by substituents. These include not only monomeric but also oligomeric compounds, which may be constructed of a plurality of phenolic units.

[0210] Hydroquinones and hydroquinone analogs are also suitable, as are substituted compounds, and also antioxidants based on tocopherols and derivatives thereof. It is also possible to use mixtures of different antioxidants. It is possible in principle to use any compounds which are customary in the trade or suitable for styrene copolymers, for example antioxidants from Irganox® range. In addition to the phenolic antioxidants cited above by way of example, it is also possible to use so-called co-stabilizers, in particular phosphorus- or sulfur-containing co-stabilizers. These phosphorus- or sulfur-containing co-stabilizers are known to those skilled in the art.

[0211] Examples of suitable light stabilizers, as or comprised in component D, include various substituted resorcinols, salicylates, benzotriazoles and benzophenones.

[0212] Suitable matting agents, as or comprised in component D, include not only inorganic substances such as talc, glass beads or metal carbonates (for example MgCCh, CaCCh) but also polymer particles based on, for example, methyl methacrylate, styrene compounds, acrylonitrile or mixtures thereof. It is further also possible to use polymers comprising copolymerized acidic and / or basic monomers.

[0213] Examples of suitable antidrip agents, as or comprised in component D, include polytetrafluoroethylene (Teflon) polymers and ultrahigh molecular weight polystyrene (weightaverage molar mass Mw above 2,000,000 g / mol).

[0214] Examples of suitable antistatic agents include amine derivatives such as N,N-bis(hydrox- yalkyl)alkylamines or -alkyleneamines, polyethylene glycol esters, copolymers of ethylene oxide glycol and propylene oxide glycol (in particular two-block or three-block copolymers of ethylene oxide blocks and propylene oxide blocks), and glycerol mono- and distearates, and mixtures thereof.

[0215] Examples of suitable light stabilizers include hindered phenols but also vitamin E / com- pounds having analogous structures and butylated condensation products of p-cresol and dicyclopentadiene. HALS stabilizers (Hindered Amine Light Stabilizers), benzophenones, resorcinols, salicylates, benzotriazoles are also suitable. Other suitable compounds include, for example, thiocarboxylic esters.

[0216] Also usable are Ce-C2o-alkyl esters of thiopropionic acid, in particular the stearyl esters and lauryl esters. It is also possible to use the dilauryl ester of thiodipropionic acid (dilauryl thiodipropionate), the distearyl ester of thiodipropionic acid (distearyl thiodipropionate) or mixtures thereof. Examples of further additives include HALS absorbers, such as bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate (Tinuvin® 770) or UV absorbers such as 2H-benzotriazol-2-yl-(4-methylphenol). Such additives are typically used in amounts of from 0.01 to 2 wt.-%, based on the total weight of the thermoplastic ABS molding composition.

[0217] Suitable lubricants and demolding agents, as or comprised in component D, include stearic acids, stearyl alcohol, stearic esters, amide waxes (bisstearylamide), polyolefin waxes and / or generally higher fatty acids, derivatives thereof and corresponding fatty acid mixtures comprising 12 to 30 carbon atoms. Also particularly suitable is ethylenebisstearamide. Typical amounts are in the range of 0 to 5 wt.-%, - based on the total weight of the thermoplastic ABS molding composition.

[0218] Also suitable additives are silicone oils, oligomeric isobutylene or similar substances. Typical amounts, when employed, are from 0.001 to 3 wt.-%, - based on the total weight of the thermoplastic ABS molding composition.

[0219] Also usable are pigments, dyes, optical brighteners, such as ultramarine blue, phthalocyanines, titanium dioxide, cadmium sulfides, derivatives of perylenetetracarboxylic acid.

[0220] Processing assistants and stabilizers such as UV stabilizers, heat stabilizers (for example butylated reaction products of p-cresol and dicyclopentadiene, Wingstay L from Om- nova, or else the dilauryl ester of thiodipropionic acid, Irganox PS 800 from BASF), lubricants and antistatic agents (for example ethylene oxide-propylene oxide copolymers such as Pluronic from BASF), when employed, are typically used in amounts of 0.01 to 5 wt.-%, based on the total weight of the thermoplastic ABS molding composition.

[0221] The individual substances added as component D are generally used in the respective customary amounts.

[0222] Process for the preparation of the thermoplastic ABS molding composition A further aspect of the invention is a process for the preparation of a thermoplastic ABS molding composition according to the invention by (melt-)mixing the components A, B, D and, if present, C, preferably by conjoint extrusion, kneading or rolling of the components, more preferably by conjoint extrusion. Preferably in said process for the preparation of a thermoplastic ABS molding composition according to the invention the components A, B, D and, if present, C, are (melt-)mixed by conjoint extrusion by using at least one extruder.

[0223] The (melt-)mixing is preferably done at temperatures in the range of from 160°C to 400°C, more preferably from 180°C to 280°C. In a preferred embodiment, component B is first partially isolated, i.e. by conducting optional steps (iv) and / or (vii), from the aqueous dispersion obtained in the step (iii) of the process for the preparation of graft copolymer B according to the invention.

[0224] Such melt mixing processes are commonly known. A suitable melt mixing process and at least one extruder as aforementioned are described in US 6,165,399. In a preferred embodiment, the at least one extruder is a twin-screw extruder.

[0225] The thermoplastic ABS molding composition can be introduced from the at least one extruder, in particular via a melt pump, into a melt-pelletization procedure, in particular an underwater pelletization procedure. Appropriate devices are known. It is preferable that the thermoplastic ABS molding composition emerging from a pelletizing die or other die attached after the melt pump is cooled, whereupon the thermoplastic molding composition solidifies, and is optionally pelletized.

[0226] To produce a molding, as product obtained by injection molding and / or extrusion, the pellets or granules are typically heated to a temperature in a range from 200°C to 280°C and thereby melted again. The mold temperature for solidifying the molding is preferably in a range from 40°C to 80°C.

[0227] The invention further relates to a shaped article, granulate, foil and / or coating, produced from the thermoplastic ABS molding composition.

[0228] Use of the thermoplastic ABS molding composition

[0229] Moreover, the invention relates to a use of the thermoplastic ABS molding composition for production of shaped articles, foils and / or coatings in particular by extrusion, thermoforming and / or injection molding. Accordingly, the invention also relates to a method for production of shaped articles, foils and / or coatings in particular by extrusion, thermoforming and / or injection molding using the thermoplastic ABS molding composition according to the invention.

[0230] The shaped article, granulate, foil and / or coating can be directly produced from the thermoplastic ABS molding composition. In one embodiment, granulates are produced from the thermoplastic ABS molding composition and the shaped article, foil and / or coating are produced from the granulates.

[0231] Typical shaped articles are sheets, semi-finished products, fibers and foams.

[0232] Processing of the thermoplastic ABS molding composition to the shaped article, granulate, foil or coating may be carried out using the known processes for thermoplastic processing, in particular production may be effected by thermoforming, extruding, injection molding, calendaring, blow molding, compression molding, press sintering, deep drawing and / or sintering, preferably by injection molding.

[0233] The invention is further illustrated by the examples and claims.

[0234] Testing methods

[0235] The analytical methods used to characterize the polymers are briefly summarized: a) Charpy notched impact strength [kJ / m2]:

[0236] The notched impact strength is determined on test specimens (80x10x4 mm, produced by injection molding at a compound temperature of 240°C and a mold temperature of 70°C) at 23°C according to ISO 179-1A:2010-11. b) Flowability (MVR [mL / 10 min]):

[0237] The flowability is determined on a polymer melt at 220°C with a load of 10 kg according to ISO 1133:2012-03. c) Particle size [nm]:

[0238] The weight mean average particle diameter Dw and the weight median particle size Dso of the graft rubber basis B1 , the fractions x) and y) of the agglomerated graft rubber basis B1 , and the graft copolymer B were measured using a CPS Instruments Inc. DC 24000 disc centrifuge. Measurement was performed in 17.1 mL of an aqueous sugar solution with a sucrose density gradient of from 8 to 20 wt.-% to achieve stable flotation behavior of the particles. A polybutadiene latex having a narrow distribution and an average particle size of 405 nm was used for calibration. The measurements were taken at a disk rotational speed of 24 000 rpm by injection of 0.1 mL of a diluted rubber dispersion (aqueous 24 wt.-% sucrose solution, comprising about 0.2-2 wt.-% of rubber particles) into the disc centrifuge containing the aqueous sugar solution having a sucrose density gradient of 8 to 20 wt.-%.

[0239] The weight mean average particle diameter Dw and the weight median particle size Dso of the agglomerating copolymer (BC) were measured with the CPS Instruments Inc. DC 24000 disc centrifuge using 17.1 mL of an aqueous sugar solution having a sucrose density gradient of 3.5 to 15.5 wt.-% to achieve stable sedimentation behavior of the particles. A polyurethane latex (particle density 1.098 g / mL) having a narrow distribution and an average particle size of 155 nm was used for calibration. The measurements were taken at a disk rotational speed of 24 000 rpm by injection of 0.1 mL of a diluted dispersion of the copolymer BC (produced by diluting with water to a content of 1-2 wt- %) into the disk centrifuge containing the aqueous sugar solution having a sucrose density gradient of 3.5 to 15.5 wt.-%. d) Solids contents:

[0240] The solids contents were measured after drying the latex samples at 180°C for 25 min in a drying cabinet. e) Swelling index SI and gel content [%]:

[0241] The gel content and swelling index values were determined with the wire cage method in toluene (see Houben-Weyl, Methoden der Organischen Chemie, Makromolekulare Stoffe, part 1 , page 307 (1961) Thieme Verlag Stuttgart).

[0242] A film was produced from the aqueous dispersion of the graft rubber basis B1 by evaporation of the water. 0.5 g of this film was admixed with 250 mL of toluene. After 72 hours, the toluene was removed from the swelled sample and the sample was weighed. After 1 hour of drying in vacuum at 150° C the sample was weighed again.

[0243] The swelling index is determined by: Swelling index SI = (mass of swelled gel with toluene prior to drying) I (mass of gel after drying)

[0244] The gel content is determined by:

[0245] Gel content = (mass of sample dried in vacuum) I (mass of sample prior to swelling) * 100%. f) Gloss characteristics:

[0246] The gloss is determined in accordance with DIN 67530:1982-01 at an angle of 20°.

[0247] Method X: To determine the gloss characteristics for good injection molding conditions X, rectangular platelets having dimensions of 75 mm x 50 mm x2 mm are produced from the polymer melt using an injection molding machine at a compound temperature of 250°C and a mold temperature of 80°C.

[0248] Method Y: To determine the gloss characteristics for non-optimal injection molding conditions Y, rectangular platelets having dimensions of 75 mm x 50 mm x 2 mm are produced from the polymer melt using an injection molding machine at a compound temperature of 250°C and a mold temperature of 50°C.

[0249] Method Z: To determine the gloss characteristics for non-optimal injection molding conditions Z, rectangular platelets having dimensions of 75 mm x 50 mm x 2 mm are produced from the polymer melt using an injection molding machine at a compound temperature of 250°C and a mold temperature of 40°C.

[0250] The gloss ratio is determined by the formula:

[0251] ( 20° gloss method Y + 20° gloss method Z ) 100 [%] g) Yellowness index Yl:

[0252] The Yl value is determined according to ASTM method E313-96 (illuminant / observer combination 0 / 2°) on the same platelets having dimensions of 75 mm x 50 mm x 2 mm which were used to determine the gloss for good injection molding conditions, method X. h) Vicat softening temperature: Vicat softening temperature (unit °C) is determined according to ISO 306:2004 (method B50).

[0253] Materials

[0254] The materials used in the examples and comparative examples are described in the following. First, components A and D are described, followed by the description of component B and its preparation according to the invention and the description of comparative graft copolymer B-c1 and its preparation.

[0255] Component A

[0256] Statistical SAN copolymer (component A) with 23.5 wt.-% acrylonitrile content - produced by continuous radical solution polymerization from styrene and acrylonitrile with ethyl benzene as a solvent - with a viscosity number of 64 mL / g (concentration 5 g / L in dimethylformamide measured at 20°C) and a melt flow rate (MVR) of 64 [mL / 10 min] - measured at 220°C and 10 kg load according to ISO 1133.

[0257] Component D

[0258] Component D is a mixture of Wingstay L, Irganox PS800 and silicon oil with a viscosity of 60,000 mPas in a weight ratio of 28.5 : 57.2 : 14.3.

[0259] Component B

[0260] The preparation of component B and the ABS molding composition is described in the following for the inventive and comparative examples. The term “parts” is based on weight in the context of the present application. The process can be used at a large scale.

[0261] The obtained graft copolymers (component B) and the obtained ABS molding compositions are characterized according to the methods described above. The determined data are summarized in Table 1.

[0262] Graft rubber basis B1 (component B1) The graft rubber basis B1 is produced by emulsion polymerization using a feed stream addition process. Demineralized water, potassium stearate, sodium persulfate and sodium hydrogencarbonate are provided first and the temperature is set to 67°C throughout the whole polymerization process. The monomers are introduced into the reactor in the following order: Initially, styrene is added in an amount of 7 wt.-%, - based on the total weight of monomers forming B1 -, over 10 minutes. Following the styrene addition, a first portion of 1 ,3-butadiene is added over 21 minutes. After a break of 5 minutes, a second portion of 1 ,3-butadiene is subsequently added over 7.5 hours, tert.-dodecylmercaptan is added in an amount of 41.7 wt.-%, - based on the total amount of tert.-dodecylmercaptan used -, at the start of the first portion of 1 ,3-butadiene, another amount of 41.7 wt.-% is added 4 hours after start of styrene feed and another amount of 16.6 wt.-% is added 8 hours after start of styrene feed.

[0263] The polymerized amounts of monomers forming B1 are: 3180 parts styrene, 4693 parts 1 ,3-butadiene (first portion) and 37554 parts 1 ,3-butadiene (second, remaining portion). The applied amounts of other reaction components are 363.4 parts tert.-dodecylmercaptan), 98.6 parts sodium persulfate, 338 parts potassium stearate and 159.5 parts sodium hydrogencarbonate. After the end of the feeding of the second, remaining portion of 1 ,3- butadiene, a temperature of 67°C and a maximum pressure of 7.8 bar are applied for a residence time of 2 h, before going to atmospheric pressure. The resulting latex of B1 has a solids content of 44.6 wt.-%.

[0264] Following this recipe, component B1 shows a weight median particle size Dso in the range of 95 to 105 nm, a swelling index in the range of 20 to 28 and a gel content in the range of 67 to 72%, when multiple batches are repeated.

[0265] Aqqlomeratinq copolymer (BC)

[0266] The agglomerating copolymer is produced by emulsion polymerization. First, 62.0 parts of Mersolat H30 (Lanxess Deutschland GmbH, emulsifier, C12-C18 — SC>3"K+, CAS Registry Number: 68188-18-1 , solids content 30 wt.-%) are diluted with 7280.8 parts of demineralized water and heated to 68°C with stirring under a nitrogen atmosphere. A solution made from 28.36 parts of sodium peroxodisulfate, 3.15 parts of sodium bicarbonate, 10.21 parts of an aqueous sodium hydroxide solution (32 wt.-%) and 1386.3 parts demineralized water is added with continued stirring. After 10 minutes, 1397 parts of ethyl acrylate are introduced over 18 minutes with a concomitant temperature increase from 68°C to 85°C.

[0267] After cooling to 73°C within 30 min, the following three feeds are introduced over 210 minutes with a concomitant temperature increase to 85°C: • 11101 .6 parts of ethyl acrylate;

[0268] • solution of 22.39 parts of sodium persulfate, 2.49 parts of sodium bicarbonate and 8.06 of a solution of sodium hydroxide (32 wt.-% in water) in 1094.8 parts of demineralized water

[0269] • solution of 549.6 parts of Mersolat H30 (Lanxess Deutschland GmbH) and 594.9 parts of methacrylamide in 6458.9 parts of demineralized water.

[0270] Temperature is kept at 85°C. Once addition of the three feeds is completed, the polymerization is continued for 75 minutes at 85°C with stirring. This is followed by cooling to room temperature and addition of 2800 parts of demineralized water. The solids content of the latex of the agglomerating copolymer BC1 is 40.7 wt.-%. The weight median particle size Dso is in the range of 118 to 124 nm and the polydispersity II is in the range of 0.24 to 0.27, when multiple batches are repeated.

[0271] Agglomerated graft rubber basis B1

[0272] The agglomerated graft rubber basis B1 is produced according to the following procedure. First, 57290 parts of the latex of the graft rubber basis B1 , - based on the dry weight of B1 -, are initially charged at a temperature of 63°C, diluted with 85770 parts of demineralized water and stirred. 1570 parts of the latex of the obtained agglomerating copolymer (BC), - based on the dry weight of BC -, are diluted with 13373 parts of demineralized water. The diluted latex of BC is then added over 25 minutes with stirring to agglomerate the graft rubber basis B1. After two minutes 542.7 parts of potassium stearate dissolved in 9600 parts of demineralized water having a temperature of 65°C is added to the latex of the agglomerated graft rubber basis B1 with continued stirring.

[0273] The particle size distribution of the agglomerated graft rubber basis B1 is measured. Only a fraction of the particles in the latex of the graft rubber basis B1 is agglomerated to larger particles.

[0274] The agglomeration yield is the fraction of the agglomerated particles in wt.-% based on the total weight of the particles. The agglomeration yield is determined from the cumulative distribution curve of the particle size measurement. The weight median particle size D50 of the fraction of agglomerated particles (= fraction y) in the obtained latex of the agglomerated graft rubber basis B1 is in the range of 340 to 360 nm and the fraction y is in the range of 60 to 80 wt.-%, when multiple batches are repeated.

[0275] The agglomerated graft rubber basis B1 is used for the grafting step for the comparative examples and inventive examples. Comparative example 1 (c1):

[0276] Graft copolymer B-c1

[0277] Once the agglomeration step is completed, 49.7 parts of sodium persulfate (initiator; first portion) dissolved in 23686 parts of demineralized water are added to the latex of the agglomerated graft rubber basis B1 (as obtained in the quantities according to the agglomeration procedure above) with continued stirring at a temperature of 66°C. After the addition of the initiator solution, at a (start feeding) temperature of 66.5°C, a monomer mixture of 31546.2 parts of styrene and 7641.7 parts of acrylonitrile is added over two hours and 44 minutes while stirring is continued. The temperature is increased linearly to 80°C over this time period of addition of the styrene / acrylonitrile mixture. Once the addition of the styrene / acrylonitrile mixture is completed, 74.5 parts of sodium persulfate (second portion) dissolved in 4415 parts of demineralized water are added under continued stirring. The polymerization is continued for 75 minutes at 80°C and then 190.5 parts of a stabilizer dispersion (Wingstay L, butylated reaction product of p-cresol and dicyclopentadiene, CAS No.: 68610-51-5, based on solids of the dispersion having a solids content of 50 wt.-%) are added to the obtained graft copolymer B latex, which has a solids content of 40.7 wt.-%.

[0278] The latex of component B is then precipitated with an aqueous magnesium sulfate solution at a temperature of 88°C and dried.

[0279] ABS molding composition

[0280] Subsequently, the obtained component B (dry powder) and components A and D are melt-mixed in a twin-screw extruder at a rpm of 400, resulting in a thermoplastic ABS molding composition. In the extrusion zone, the temperature is set at 200 to 250°C. The resulting thermoplastic ABS molding composition is palletized after cooling. The batch size for all examples is 9 kg.

[0281] The weight ratio of the used components A:B:D is 67.82 : 32.00 : 0.18. Component C is absent.

[0282] The test results of the obtained thermoplastic ABS molding compositions are shown in Table 1.

[0283] The obtained thermoplastic ABS molding composition c1 of comparative example 1 showed a flowability MVR (220°C) of 14.9 mL / 10 min, a Charpy notched impact strength of 22.5 kJ / m2, a Vicat B50 temperature of 93.7 °C and a yellowness index of 25.7. The gloss for good injection molding conditions X (method X) is 95.8. The gloss for non- optimal injection molding condition Y (method Y) is 75.1. The gloss for non-optimal injection molding condition Z (method Z) is 61.1. The gloss ratio is 71.1%.

[0284] Comparative examples 2 and 3

[0285] Further comparative examples 2 to 3 were performed according to the comparative example 1 with the following differences:

[0286] The molecular weight regulator (or chain transfer agent) tert-dodecylmercaptan is used in the grafting step (iii).

[0287] Comparative example 1 (c1): no tert-dodecylmercaptan is used.

[0288] Comparative example 2 (c2): 33.5 parts of tert-dodecylmercaptan are added at the same time when the monomer mixture of 31546.2 parts of styrene and 7641.7 parts of acrylonitrile is added over two hours and 44 minutes while stirring is continued.

[0289] It is obvious (cp. Table 1) from the gloss measurements that the gloss and the gloss ratio of the obtained ABS molding composition c-2 is further decreased by using tert-dodecylmercaptan in the grafting step (iii).

[0290] Comparative example 3 (c3): 59.5 parts of tert-dodecylmercaptan are added at the same time when the monomer mixture of 31546.2 parts of styrene and 7641.7 parts of acrylonitrile is added over two hours and 44 minutes while stirring is continued.

[0291] It is obvious (cp. Table 1) from the gloss measurements that the gloss and the gloss ratio of the obtained ABS molding composition c-3 is further decreased by using tert-dodecylmercaptan in the grafting step (iii).

[0292] Inventive examples 4 to 9

[0293] The inventive examples 4 to 9 were performed according to the comparative example 1 with the following differences in grafting step (iii):

[0294] Inventive example 4: faster increase from start temperature to end temperature.

[0295] Comparative example 1 : temperature increase from 66.5°C to 80°C in 2 hours and 44 minutes (164 minutes).

[0296] Inventive example 4: temperature increase from 66.5°C to 80°C in 1 hour and 23 minutes (83 minutes). A faster increase of the temperature in grafting step (iii) as in example 4 resulted in a good gloss ratio (cp. Table 1).

[0297] Inventive examples 5 and 6: The amount of initiator applied at the start (first portion) is 60% by weight or 66.7% by weight respectively, while the amount of initiator in the second portion is 40 % by weight or 33.3 % by weight respectively, each based on the total amount of initiator applied in the grafting step (iii).

[0298] Comparative example 1 : The amount of sodium persulfate in the first portion is 49.7 parts (40 wt.-% based on the total amount of initiator applied in grafting step (iii)) dissolved in 23686 parts of demineralized water, while the amount of sodium persulfate in the second portion is 74.5 parts (60 wt.-% based on the total amount of initiator applied in the grafting step (iii)) dissolved in 4415 parts of demineralized water.

[0299] Inventive example 5: The same total amount of sodium persulfate as in comparative example 1 is used, but the amount in the first portion is higher than in the second portion. The amount of sodium persulfate in the first portion is 74.5 parts (60 wt.-% based on the total amount of initiator applied in the grafting step (iii)) dissolved in 23686 parts of demineralized water, while the amount of sodium persulfate in the second portion is 49.7 parts (40 wt.-% based on total amount of initiator applied in the grafting step (iii)) dissolved in 4415 parts of demineralized water.

[0300] Inventive example 6: A higher amount of the initiator applied at the start (first portion) is used, while the amount of initiator in the second portion is kept the same as in comparative example 1 . This leads to a higher total amount of initiator applied in the grafting step (iii) and higher amount of initiator in the first portion compared to the second portion. The amount of sodium persulfate in the first portion is 149.0 parts (66.7 wt.-% based on the total amount of initiator applied in the grafting step (iii)) dissolved in 23686 parts of demineralized water, while the amount of sodium persulfate in the second portion is 74.5 parts (33.3 wt.-% based on the total amount of initiator applied in the grafting step (iii)) dissolved in 4415 parts of demineralized water.

[0301] The gloss ratio is improved for the inventive examples 5 and 6 (cp. Table 1).

[0302] Reference example 7: increased monomer feed time.

[0303] Comparative example 1 : monomer feed time is 2 hours and 44 minutes (164 minutes). Reference example 7: monomerfeed time is 3 hours and 26 minutes (206 minutes). After the monomer feed is complete, the second initiator portion (74.5 parts of sodium persulfate dissolved in 4415 parts of demineralized water) is added under continued stirring.

[0304] The gloss ratio of reference example 7 is improved compared to comparative example 1 (cp. Table 1). However, the total batch cycle time is increased by 42 minutes which is economical less attractive. combination of process conditions from examples 4 and 5 (i.e. faster increase from start temperature to end temperature; the amount of initiator applied at the start (first portion) is 60% by weight, while the amount of initiator in the second portion is 40 % by weight, each based on total amount of initiator applied in the grafting step (iii).

[0305] Comparative example 1 : The temperature is increased from 66.5°C to 80°C in 2 hours and 44 minutes (164 minutes) and the amount of sodium persulfate in the first portion is 49.7 parts (40 wt.-% based on total amount of initiator applied in grafting step (iii)) dissolved in 23686 parts of demineralized water, while the amount of sodium persulfate in the second portion is 74.5 parts (60 wt.-% based on total amount of initiator applied in the grafting step (iii)) dissolved in 4415 parts of demineralized water.

[0306] Inventive example 8: The temperature is increased from 66.5°C to 80°C in 1 hour and 23 minutes (83 minutes) and the amount of sodium persulfate in the first portion is 74.5 parts (60 wt.-% based on total amount of initiator applied in the grafting step (iii)) dissolved in 23686 parts of demineralized water, while the amount of sodium persulfate in the second portion is 49.7 parts (40 wt.-% based on total amount of initiator applied in the grafting step (iii)) dissolved in 4415 parts of demineralized water.

[0307] The combination of faster increase from start temperature to end temperature and the higher amount of initiator in the first portion compared to the second portion resulted in the best gloss ratio (cp. Table 1 , example 8) of the obtained molding composition as well as in good and balanced mechanical (high Charpy notched impact strength, flowability, Vicat temperature) and optical properties (yellowness).

[0308] Inventive 9 combination of process conditions from example 4 and 6 (i.e. faster increase from start temperature to end temperature and higher amount of initiator used at the start (first portion), while keeping the amount of initiator in the second portion the same, each compared to the comparative example 1. Comparative example 1 : The temperature is increased from 66.5°C to 80°C in 2 hours and 44 minutes (164 minutes) and the amount of sodium persulfate in the first portion is 49.7 parts (40 wt.-% based on total amount of initiator applied in the grafting step (iii)) dissolved in 23686 parts of demineralized water, while the amount of sodium persulfate in the second portion is 74.5 parts (60 wt.-% based on total amount of initiator applied in the grafting step (iii)) dissolved in 4415 parts of demineralized water.

[0309] Inventive example 9: The temperature is increased from 66.5°C to 80°C in 1 hour and 23 minutes (83 minutes) and the amount of sodium persulfate in the first portion is 149.0 parts (66.7 wt.-% based on total amount of initiator applied in the grafting step (iii)) dissolved in 23686 parts of demineralized water, while the amount of sodium persulfate in the second portion is 74.5 parts (33.3 wt.-% based on total amount of initiator applied in the grafting step (iii)) dissolved in 4415 parts of demineralized water.

[0310] Table 1 : ABS molding compositions, test results

[0311] *) c = comparative, i = inventive, r = reference

Claims

Patent claims1 . Process for the preparation of a graft copolymer B (component B) comprising:B1 : 30 to 90 wt.-%, preferably 40 to 85 wt.-%, - based on the dry weight of B of at least one graft rubber basis B1 (component B1) having a glass transition temperature of less than 0°C, comprising:B11 : 50 to 100 wt.-%, - based on the total weight of monomers forming B1 - , of one or more of butadiene or isoprene (component B11), in particular butadiene, andB12: 0 to 50 wt.-%, - based on the total weight of monomers forming B1 of at least one further monomer (component B12) selected from the group consisting of: styrene, a-methylstyrene, acrylonitrile, methacrylonitrile, methyl methacrylate, maleic acid anhydride, and N-phenylma- leimide, in particular styrene; where (B11) and (B12) sum to 100 wt.-%;B2: 10 to 70 wt.-%, preferably 15 to 60 wt.-%, - based on the dry weight of B -, of one or more graft sheaths B2 (component B2) comprising:B21 : 50 to 90 wt.-%, - based on the total weight of monomers forming B2 -, of styrene, a-methylstyrene and / or p-methyl-styrene (component B21), in particular styrene;B22: 10 to 50 wt.-%, - based on the total weight of monomers forming B2 -, of (meth)acrylonitrile (component B22), in particular acrylonitrile;B23: 0 to 40 wt.-%, - based on the total weight of monomers forming B2 -, of one or more co-polymerizable monomers (component B23), preferably Ci-Cs-acrylates and / or methyl methacrylate, where (B21), (B22) and (B23) sum to 100 wt.-%, and where components B1 and B2 sum to 100 wt.-%; which process comprises the following steps:(i) polymerizing components B11 and optionally B12 to obtain at least one graft rubber basis B1 ;(ii) agglomerating the graft rubber basis B1 (obtained in step (i)) by adding an agglomeration agent, preferably an agglomerating copolymer (BC); and(iii) graft polymerization of components B21 , B22, and optionally B23 in presence of the agglomerated graft rubber basis B1 (obtained in step (ii)) by feeding at least one polymerization initiator in at least two portions, whereof a first portion of the initiator is fed at the start before feeding and copolymerizing components B21 , B22 and optionally B23 to obtain graft copolymer B; wherein in step (iii) at least one of the process conditions a) and / or b) in combination with process condition c) is applied:a) temperature increase during the feeding of components B21 , B22, and optionally B23 within 1 hour and 45 minutes or less to a temperature of at least 10°C higher than the temperature at the start of feeding said components; b) amount of the initiator applied at the start (first portion) is at least 52 % by weight, based on the total amount of initiator applied in step (iii); and c) no molecular weight regulator or chain transfer agent is used in step (iii).

2. Process for the preparation of a graft copolymer B according to claim 1 wherein process steps (i) and (iii) are performed in an aqueous emulsion.

3. Process for the preparation of a graft copolymer B according to claim 1 or 2 where in step (iii) under process condition a) the temperature at the start of feeding components B21 , B22, and optionally B23 is in the range of 62 to 72°C, and the temperature is increased within 1 hour and 45 minutes or less, often within a period of 1 hour and 45 minutes to 1 hour and 20 minutes, from the start temperature to a temperature of at least 10°C higher than the start temperature.

4. Process for the preparation of a graft copolymer B according to any of claims 1 to3 where in step (iii) under process condition a) the temperature at the start of feeding components B21 , B22, and optionally B23 is in the range of 64 to 72°C, and the temperature is increased within 1 hour and 45 minutes or less, often within a period of 1 hour and 45 minutes to 1 hour and 20 minutes, from the start temperature to a temperature of at least 10°C higher than the start temperature.

5. Process for the preparation of a graft copolymer B according to any of claims 1 to4 where in step (iii) the at least one polymerization initiator is fed in two portions.

6. Process for the preparation of a graft copolymer B according to any of claims 1 to5 wherein in step (iii) under process condition b) the amount of the initiator applied at the start is at least 55 % by weight, preferably at least 60 % by weight, based on the total amount of initiator applied in step (iii).

7. Process for the preparation of a graft copolymer B according to any of claims 1 to6 where in step (iii) process conditions a), b) and c) are combined.

8. Process for the preparation of a graft copolymer B according to any of claims 1 to7 which further comprises a process step (iv) for isolation of graft copolymer B from the reaction mixture by spray drying, shearing or by precipitation with strong acids or inorganic salts, preferably by precipitation with inorganic salts.

9. Process for the preparation of a graft copolymer B according to any of claims 1 to 8 where in step (ii) the agglomeration agent is an agglomerating copolymer (BC) of (BC1) one or more hydrophobic monomers selected from the group consisting of Ci to C12 alkyl acrylates, Ci to C12 alkyl methacrylates, and mixtures thereof, and (BC2) one or more hydrophilic comonomers selected from the group consisting of methacrylamide, acrylamide, methylacrylamide, ethylacrylamide, n-butylacryla- mide, and mixtures thereof.

10. Process for the preparation of a graft copolymer B according to any of claims 1 to 9, wherein graft copolymer B comprises 40 to 85 wt.-% of the graft rubber basis (B1) and 15 to 60 wt.-% of one or more graft sheaths B2 (component B2), - each based on the dry weight of B -, and where the graft rubber basis B1 comprises: B11 : 79 to 100 wt.-% butadiene and / or isoprene, preferably butadiene, - based on the total weight of monomers forming B1 , andB12: 0 to 21 wt.-% a-methylstyrene and / or styrene, preferably styrene, - based on the total weight of monomers forming B1 , where B11 and B12 sum to 100 wt.-%, and where the graft sheath B2 comprises:(B21) 70 to 90 wt.-% of styrene and / or a-methylstyrene, in particular styrene, - based on the total weight of monomers forming B2 -, and(B22) 10 to 30 wt.-% of acrylonitrile and / or methacrylonitrile, in particular acrylonitrile, - based on the total weight of monomers forming B2 -, wherein component (B23) is not present, and where (B21) and (B22) sum to 100 wt.-%, and where components B1 and B2 sum to 100 wt.-%.11 . Process for the preparation of a graft copolymer B according to claim 9, wherein agglomerating copolymer (BC) comprises:(BC1): 80 to 99.9 wt.-% of ethyl acrylate, - based on the total weight of monomers forming BC -, and(BC2): 0.1 to 20 wt.-% of methacrylamide, - based on the total weight of monomers forming BC -, where (BC1) and (BC2) sum to 100 wt.-%, and where the agglomerating copolymer (BC) has a weight median particle size D50 in the range of 100 to 150 nm, preferably of 110 to 150 nm, and a polydispersity II larger than 0.27 or of 0.27 or less, preferably less than 0.27, preferably in the range of 0.27 to 0.15, and the agglomerated graft rubber basis B1 has a weight-based, bimodal particle size distribution of a fraction x) of non-agglomerated particles in an amount of 15 to 40wt.-%, - based on the total weight of all particles having a weight median particle size Dso of not more than 150 nm, preferably in the range of 80 to 120 nm and a fraction y) of agglomerated particles in an amount of 60 to 85 wt.-%, - based on the total weight of all particles having a weight median particle size D50 in the range of 300 to 650 nm, preferably 300 to 550 nm, where x) and y) sum to 100 wt- %.

12. Graft copolymer B obtained by the process according to any of claims 1 to 11.

13. Thermoplastic ABS molding composition comprising at least one graft copolymer B according to claim 12, at least one (rubber-free) styrenic copolymer matrix A, one or more additives D, and optionally one or more thermoplastic polymers C selected from the group consisting of polycarbonates, polyesters, polyester carbonates and polyamides.

14. Thermoplastic ABS molding composition according to claim 13 comprising:A: 39.99 to 80 wt.-%, - based on the total weight of the molding composition -, of at least one (rubber-free) styrenic copolymer matrix A comprising:A11 : 60 to 80 wt.-%, preferably 69 to 80 wt.-%, - based on the total weight of A -, of styrene and / or a-methylstyrene and / or p-methyl-styrene (component A11), preferably styrene; andA12: 20 to 40 wt.-%, preferably 20 to 31 wt.-%, - based on the total weight of A -, of (meth)acrylonitrile (component A12), preferably acrylonitrile; andA13: 0 to 20 wt.-%, preferably 0 to 11 wt.-%, - based on the total weight of A -, of one or more co-polymerizable monomers (component A13), preferably Ci-Cs-acrylates and / or methyl methacrylate; where the components A11 , A12 and, if present, A13 sum to 100 wt.-%.B: 19.99 to 60 wt.-%, - based on the total weight of the molding composition -, of at least one graft copolymer B according to claim 12;C: 0 to 40 wt.-%, - based on the total weight of the molding composition -, of at least one thermoplastic polymer C; andD: 0.01 to 20 wt.-%, - based on the total weight of the molding composition -, of one or more additives D (component D), in particular selected from the group consisting of: stabilizers, dispersants, pigments, lubricants, dyes, colorants, inorganic fillers, organic fillers, antistatic agents, flame retardants, antidrip agents and matting agents; where the components A, B, D and, if present, C sum to 100 wt.-%.

15. Process for the preparation of a thermoplastic ABS molding composition according to claim 13 or 14 by (melt-)mixing the components A, B, D and, if present, C, preferably by conjoint extrusion, kneading or rolling of the components, more preferably by conjoint extrusion.

16. Use of a thermoplastic ABS molding composition according to claim 13 or 14 for the production of shaped articles, foils and / or coatings in particular by extrusion, thermoforming and / or injection molding.

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