Patent Application
20240287302
The present invention relates to a weather resistant acrylonitrile styrene acrylate (ASA) molding composition with improved toughness and reduced yellowness, a process for the preparation of the (thermoplastic) molding composition, shaped articles produced therefrom and its use for various applications.
Thermoplastic acrylonitrile styrene acrylate molding compositions comprising ASA graft copolymers are widely used in automotive, construction and recreation industries mainly due to their good weathering resistance. Various injection- and extrusion molding compositions comprising ASA graft copolymer products are used directly in outdoors without application of coatings or paints.
The core of ASA graft copolymers, an acrylic ester elastomer by virtue of its chemical structure is devoid of any double bonds (C═C) in the main polymer chain. This characteristic of ASA graft copolymers makes them withstand exposure to UV rays, ozone, heat etc. Moreover, ASA graft copolymers have a very good heat resistance. Other polymers considered for similar applications, like ABS graft copolymers and PVC, have very low weathering and heat resistance and undergo color/shade changes on exposure to heat or UV (weathering).
ASA molding compositions are often used pre-colored by addition of pigments as their excellent weathering resistance property does not demand for painting. Usually the dosing of pigments is very high in ASA molding compositions due to the difference in refractive indices of the acrylate rubber polymer and the matrix polymer, often a SAN copolymer. Higher pigment loading further enhances the weathering performance of ASA molding compositions but a high pigment loading is costly and often disadvantageous for the mechanical properties.
The inherent nature of the acrylate rubber core material enhances the above mentioned characteristics of ASA molding compositions, however, there are certain drawbacks also due to a lower flexibility of the stiffer main polymer chain of an acrylate in comparison to a conjugated diene used for ABS graft copolymers. Compared to ABS molding compositions, the impact properties at room temperature and lower temperatures are generally lower for ASA molding compositions.
In order to improve the fluidity and/or toughness, various ASA molding compositions have been proposed.
CN 104592667 A describes a high-flow, high-impact ASA composition comprising 20 to 40 wt.-% ASA graft copolymer, 60 to 80 wt.-% of 2 SAN copolymers with different melt flow rates (10-20 g/10 min and 40 to 60 g/10 min; 220° C., 10 kg load) and 2 to 10 wt.-% styrene-maleic anhydride (SMA) as compatibilizer. The ASA graft copolymer has a rubber content 40 to 80 wt.-%; the particle size of the rubber is not mentioned.
JP 2020-176238 A discloses a resin composition containing a PC/ASA-resin (X) and a modified EVA copolymer (Y) which is a graft copolymer obtained by polymerization of styrene, GMA and an epoxy group containing monomer in the presence of the EVA copolymer (A). The EVA copolymer (A) having a VA content of 1 to 30 wt.-%, preferably 3 to 20 wt.-% is preferably used in an amount of 50 or 70 wt.-%; Graft copolymer (Y) is mostly used in an amount of 5 pbw related to 100 pbw PC/ASA resin.
CN 109627622 A describes an ultra-high-flow, high-impact, weather resistant ASA composition comprising 25 to 40 pbw ASA graft copolymer, 50 to 75 pbw SAN copolymer and 3 to 10 pbw flow modifier with a melt flow rate (MFR) of >100 g/10 min (220° C., 10 kg load) selected from EMH (ethylene-acrylate maleic anhydride terpolymer), EBA (ethylene-butyl acrylate copolymer) and EVA (ethylene vinyl acetate copolymer). The rubber content of the ASA graft copolymer is 60 to 70 wt.-%; its particle size is not mentioned. The SAN-copolymer has preferably a MFR of >50 g/10 min (200° C./10 kg); its AN-content is not disclosed. An exemplified composition comprises 8 pbw of an EVA grade 28-150 (Arkema). The ASA composition is obtained by a process wherein first all components are pre-mixed and then the obtained mixture is melt-extruded and pelletized. The ASA composition can be used as raw material for ASA/PVC synthetic resin tiles.
However, the afore-mentioned prior art compositions are still in need of improvement in respect of properties such as yellowness/whiteness and their gloss and color retention after weathering tests.
Thus, it is an object of the invention to provide a weather resistant ASA molding composition having a high melt flow and high toughness and further a reduced yellowness and improved whiteness and gloss.
One aspect of the invention is a thermoplastic molding composition (TP) comprising (consisting of) components (A), (B), (C), (D) and (E):
If component (E) is present, its minimum amount is 0.01 wt.-%, based on the entire thermoplastic molding composition (TP).
Wt.-% means percent by weight.
The median weight particle diameter D50, also known as the D50 value of the integral mass distribution, is defined as the value at which 50 wt.-% of the particles have a diameter smaller than the D50 value and 50 wt.-% of the particles have a diameter larger than the D50 value.
In the present application the weight-average particle diameter Dw, in particular the median weight particle diameter D50, is determined with a disc centrifuge (e.g.: CPS Instruments Inc. DC 24000 with a disc rotational speed of 24 000 rpm).
The weight-average particle diameter D is defined by the following formula (see G. Lagaly, O. Schulz and R. Ziemehl, Dispersionen und Emulsionen: Eine Einführung in die Kolloidik feinverteilter Stoffe einschlieβlich der Tonminerale, Darmstadt: Steinkopf-Verlag 1997, ISBN 3-7985-1087-3, page 282, formula 8.3b):
D
w=sum(ni*di4)/sum(ni*di3)
The summation is performed from the smallest to largest diameter of the particles size distribution.
In the present application a homo- or copolymer (e.g. graft base G11 or G21, graft shell G12 or G22, copolymer S1, etc.) composed of a monomer 1 and optionally a (co)monomer 2 means a homo- or copolymer composed of polymerized units derived from monomer 1 and optionally polymerized units derived from (co)monomer 2.
It is preferable that the thermoplastic molding composition of the invention comprises (or preferably consists of):
It is particularly preferable that the molding composition comprises (or consists of):
It is more preferable that the molding composition comprises (or consists of):
It is even more preferable that the molding composition comprises (or consists of):
Preferred molding compositions (TP) consist of components (A) to (E) in the afore-mentioned amounts.
Preferably polymer mixture (A) (=component (A)) as defined above consists of:
More preferably polymer mixture (A) consists of:
Preferably polymer mixture (A) has a melt volume rate (MVR) of 27 to 57 ml/10 min (DIN EN ISO 1133-1:2012-03; 220° C./21.6 kg load).
Graft copolymer GR1 is a multiphase (=core/shell) copolymer. It is composed of a crosslinked rubbery core phase with a glass transition temperature below 0° C. and a hard phase which forms a graft shell G12 and is connected to the rubbery core phase by grafting. The rubbery core phase is designated as the graft base G11 onto which other monomers are grafted to form a graft shell G12.
The graft base G11 of graft copolymer GR1 can be prepared by any conventional polymerization technique, however, free radical emulsion polymerization is preferred (cf. US 2011/275763, p. 4, [0052] through p. 5, [0065]).
The graft base G11 is generally composed of 80 to 99.99 wt.-%, preferably 90 to 99.99 wt.-%, more preferably 95 to 99 wt.-%, of at least one C1 to C8-alkyl acrylate (C1 to C8-alkyl ester of acrylic acid) and 0.01 to 20 wt.-%, preferably 0.01 to 10 wt.-%, more preferably 1 to 5 wt.-%, of at least one di- or polyfunctional cross-linking monomer.
The C1 to C8-alkyl group of the C1 to C8-alkyl acrylate can be of linear or branched structure, often a linear structure is preferred. C2 to C8-alkyl acrylates are preferred.
Particularly suitable C1 to C8-alkyl acrylates, preferably C2 to C8-alkyl acrylates, are ethyl acrylate, 2-ethylhexyl acrylate, and n-butyl acrylate. Preference is given to 2-ethylhexyl acrylate and n-butyl acrylate, and very particular preference is given to n-butyl acrylate.
It is also possible to use a mixture of various alkyl acrylates differing in their alkyl radical.
Suitable di- or polyfunctional cross-linking monomers contain two or more double bonds capable of copolymerization which are not conjugated in the 1,3 positions.
Preferred di- or polyfunctional monomers are divinyl benzene, diallyl maleate, ethylene glycol dimethacrylate, butanediol dimethacrylate, hexanediol dimethacrylate, dihydrodicyclopentadienyl acrylate (DCPA), and the allyl esters of acrylic and methacrylic acid. Particular preference of polyfunctional monomers is given to the acrylic ester of tricyclodecenyl alcohol, which is known as dihydrodicyclopentadienyl acrylate (DCPA), and the allyl ester of methacrylic acid known as allyl methacrylate (AMA).
Processes for the preparation of a graft copolymer which is present as graft copolymer GR1 in the molding composition of the invention are known to the person skilled in the art. A suitable process, in particular by free radical emulsion polymerization, is described in detail in US 2011/0275763. US 2011/0275763 (cf. page 3, [0036] through page 6, [0086]) discloses suitable initiators, molecular weight regulators, dispersing agents, in particular emulsifiers, buffer substances etc., and suitable amounts thereof, as well as suitable polymerization conditions (process parameters such as process temperature—generally 25 to 160° C., preferably 40 to 90° C.-) which may be used for each step of the emulsion polymerization.
The median weight particle diameter D50 (by ultracentrifuge method) of the graft base G11 is generally from 50 to 165 nm, preferably from 60 to 140 nm, particularly preferably from 70 to 120 nm.
Preferably the swelling index of the graft base G11 is from 5 to 35. The swelling index is a measure of the ability of a solvent to swell a polymer. An example of a conventional swelling agent is methyl ethyl ketone or toluene. By way of example, the swelling index is determined by a method in which about 0.2 g of the solid in a graft-base dispersion converted to a film via evaporation of the water is swollen in an amount of toluene, e.g. 50 g. The toluene is removed by suction after, for example, 24 hours, and the specimen is weighed. The specimen is again weighed after it has been dried in vacuo. The swelling index is the ratio of the weight after the swelling procedure to the dry weight after final drying.
Preferably the gel content of the graft base G11 is more than 80%. The gel content is that content of the product that has been crosslinked, therefore being insoluble in a solvent. The solvent in which gel content is determined is preferably the same as that used for the swelling index. Gel content is calculated from the ratio of the dry weight after the swelling step to the weight prior to the swelling step (×100%).
The obtained graft base G11 (cf. US 2011/275763 A1, p. 4, [0052] through p. 5, [0065]) can be optionally agglomerated (cf. page 5, [0077] through page 6, [0086]). Preferably no agglomeration step is carried out.
In presence of the obtained graft base G11—optionally after agglomeration—at least one graft shell G12 is produced via an emulsion polymerization of styrene and acrylonitrile, and optionally methacrylonitrile, alpha-methylstyrene, methyl methacrylate and/or maleic anhydride or mixtures thereof. Said monomers are grafted on the graft base G11 to form at least one graft shell G12. The grafting process can be carried out in a single stage or a multistage. The graft polymerization is also preferably carried through a free radical emulsion route using free radical initiators or redox intiators (cp. US 2011/0275763 A1, page 5, [0066] to [0076]).
The obtained dispersion of graft copolymer GR1 is coagulated and optionally and preferably dried in a known manner (cp. DE-OS 1260 135, col. 5, I. 15 to 24) before further processing to obtain a solid and optionally dry product. However, it is also possible to use the wet graft copolymer GR1 directly for further processing steps (e.g. compounding steps). In this case, the solvent (water) is removed during further processing steps (e.g. extrusion).
Preferably graft copolymer GR1 is used as a dried compound, more preferably not completely dried (=residual moisture content 18 to 22 wt.-%), for the preparation of polymer mixture (A).
Graft copolymer GR1 has a median weight particle diameter D50 of 55 to 170 nm, preferably
Graft copolymer GR1 is generally composed of:
The amounts of graft base G11 and graft shell G12 always add to give a total of 100% by weight.
Generally graft shell G12 is composed of:
Preferably graft shell G12 is composed of:
Preferably in graft shell G12 styrene and/or acrylonitrile are not replaced by said other comonomers. Thus, preferably graft shell G12 is solely composed of styrene and acrylonitrile.
Copolymer S1 is a copolymer of styrene and acrylonitrile (=SAN copolymer) in a (styrene/acrylonitrile) weight ratio of from 75:25 to 60:40, preferably 70:30 to 60:40, more preferably 70:30 to 65:35, it being possible for styrene and/or acrylonitrile to be partially (less than 50 wt.-%) replaced by methacrylonitrile, methyl methacrylate, alpha-methyl styrene and/or maleic anhydride.
The afore-mentioned weight ratio means that the proportion of (polymerized units of) acrylonitrile present in copolymer S1 is from 25 to 40% by weight, preferably 30 to 40% by weight, more preferably from 30 to 35% by weight, and the proportion of (polymerized units of) styrene present in copolymer S1 is from 60 to 75% by weight, preferably 60 to 70% by weight, more preferably from 65 to 70% by weight, where the entirety of the amounts of the monomers mentioned is 100% by weight.
Copolymer S1 has a melt volume rate (MVR) of 50 to 70 ml/10 min (DIN EN ISO 1133-1:2012-03; 220° C./10 kg load).
Preferably the weight average molecular weight (Mw) of copolymer S1 is in the range of from 90,000 to 120,000 g/mol (measured via GPC using UV detection (against polystyrene calibration standards)).
Preferably in copolymer S1 styrene and/or acrylonitrile are not replaced by said other comonomers. Thus, preferably copolymer S1 is solely composed of styrene and acrylonitrile. More preferably copolymer S1 is solely composed of styrene and acrylonitrile in a weight ratio of 70:30 to 65:35.
Generally copolymer S1 has a viscosity number (VN) in the range of 50 to 100, preferably in the range of 55 to 80 ml/g (determined according to DIN 53726 at 25° C. on a 0.5 wt.-% solution of copolymer S1 in dimethylformamide).
Details relating to the preparation of such copolymers are described, for example, in DEA 2 420 358, DE-A 2 724 360 and in Kunststoff-Handbuch (Becker/Braun, Gausepohl/Gellert, volume IV, Polystyrol, Carl-Hanser-Verlag, Munich, 1996). Such copolymers prepared by mass (bulk) or solution polymerization in, for example, toluene or ethylbenzene, have proved to be particularly suitable.
Preferably polymer mixture (B) (=component (B)) as defined above consists of:
More preferably polymer mixture (B) consists of:
Graft copolymer GR2 is a multiphase (=core/shell) copolymer. It is composed of a crosslinked rubbery core phase with a glass transition temperature below 0° C. and a hard phase which forms a graft shell G22 and is connected to the rubbery core phase by grafting. The rubbery core phase is designated as the graft base G21 onto which other monomers are grafted to form a graft shell G22.
Graft copolymer GR2 has a median weight particle diameter D50 of 410 to 1000 nm, preferably from 410 to 800 nm, particularly preferably from 410 to 600 nm.
Generally graft copolymer GR2 is composed of:
Preferably graft copolymer GR2 is composed of:
The amounts of graft base G21 and graft shell G22 always add to give a total of 100% by weight.
Generally graft base G21 is composed of:
The graft base G21 is preferably composed of 90 to 99.99 wt.-%, more preferably 95 to 99 wt.-%, of at least one C1 to C8-alkyl acrylate and 0.01 to 10 wt.-%, more preferably 1 to 5 wt.-%, of at least one di- or polyfunctional cross-linking monomer.
The median weight particle diameter D50 (by ultracentrifuge method) of the graft base G21 is generally from 300 to 600 nm, preferably from 350 to 580 nm, particularly preferably from 370 to 560 nm.
Preferably the swelling index of the graft base G21 is from 5 to 25.
Generally graft shell G22 is composed of:
Preferably graft shell G22 is composed of:
Preferably in graft shell G22 styrene and/or acrylonitrile are not replaced by said other comonomers. Thus, preferably graft shell G22 is solely composed of styrene and acrylonitrile.
Suitable and preferred components such as monomers and cross-linking agents, preparation methods and characteristics—other than the median weight particle diameter D50—of the graft copolymer GR2 are as described above for GR1.
Processes for the preparation of a graft copolymer which is present as graft copolymer GR2 in the molding composition of the invention are known to the person skilled in the art and are described above in relation to graft copolymer GR1 of the molding composition of the invention. Graft copolymer GR2 can be prepared by any conventional polymerization technique, however, free radical emulsion polymerization is preferred. A suitable process, in particular by free radical emulsion polymerization, is described in detail in US 2011/0275763 (cf. page 3, [0036] through page 6, [0086]).
Suitable large size, cross-linked C1-C8 alkylacrylate polymer graft bases G21 can be produced according to known procedures for the production of large size dispersion, conveniently via seeded polymerization, as described in DE 1 911 882 for the production of ASA polymers. According to this method a small size, cross-linked acrylate latex (seed latex) having a median weight particle diameter D50 from 50 to 180 nm, preferred less than 120 nm, which is obtained from emulsion polymerization of C1-C8-alkylacrylates and cross-linking monomers, emulsifiers and possibly buffer, is subjected to a further polymerization reaction. The reaction conditions (Journal of Applied Polymer Science, Vol. 9 (1965), pages 2929 to 2938) are adjusted in way only allowing further growth of the present (seed) latex particles, without forming new latex particles. Normally an initiator is used. The particle size of the resulting graft base G21 can be adjusted by variation of the ratio of seed latex to monomers.
Preferably graft copolymer GR2 is used as a dried compound, more preferably not completely dried (residual moisture content 18 to 22 wt.-%), for the preparation of polymer mixture (B).
Copolymer S2 is a copolymer of styrene and acrylonitrile (=SAN copolymer) in a (styrene/acrylonitrile) weight ratio of from 75:25 to 60:40, preferably 70:30 to 60:40, more preferably 70:30 to 65:35, it being possible for styrene and/or acrylonitrile to be partially (less than 50 wt.-%) replaced by methacrylonitrile, methyl methacrylate, alpha-methyl styrene and/or maleic anhydride.
Copolymer S2 has a melt volume rate (MVR) of 11 to 25 ml/10 min, preferably 16 to 18 ml/10 min (DIN EN ISO 1133-1:2012-03; 220° C./10 kg load).
Preferably in copolymer S2 styrene and/or acrylonitrile are not replaced by said other comonomers. Thus, preferably copolymer S2 is solely composed of styrene and acrylonitrile. More preferably copolymer S2 is solely composed of styrene and acrylonitrile in a weight ratio of 70:30 to 65:35.
Preferably the weight average molecular weight (Mw) of copolymer S2 is in the range of from 130,000 to 160,000 g/mol (measured via GPC using UV detection (against polystyrene calibration standards)).
Generally copolymer S2 has a viscosity number (VN) in the range of 50 to 100, preferably in the range of 70 to 90 ml/g (determined according to DIN 53726 at 25° C. on a 0.5 wt.-% solution of copolymer S2 in dimethylformamide).
Suitable preparation methods for copolymer S2 are as described above for S1.
Component (C) is at least one copolymer (C) of styrene and acrylonitrile in a (styrene/acrylonitrile) weight ratio of from 75:25 to 60:40, preferably 70:30 to 60:40, more preferably 70:30 to 65:35, it being possible for styrene and/or acrylonitrile to be partially (less than 50 wt.-%) replaced by methacrylonitrile, methyl methacrylate, alpha-methyl styrene and/or maleic anhydride.
Copolymer (C) has a melt volume rate (MVR) of from 11 to 70 ml/10 min, preferably 50 to 70 ml/10 min, (DIN EN ISO 1133-1:2012-03; 220° C./10 kg load).
Preferably in copolymer (C) styrene and/or acrylonitrile are not replaced by said other comonomers. Thus, preferably copolymer (C) is solely composed of styrene and acrylonitrile. More preferably copolymer (C) is solely composed of styrene and acrylonitrile in a weight ratio of 70:30 to 65:35.
Preferably the weight average molecular weight (Mw) of copolymer (C) is in the range of from 90,000 to 160,000 g/mol, more preferably 90,000 to 120,000 g/mol (measured via GPC using UV detection (against polystyrene calibration standards)).
Generally copolymer (C) has a viscosity number (VN) in the range of 50 to 100, preferably in the range of 55 to 80 ml/g (determined according to DIN 53726 at 25° C. on a 0.5 wt.-% solution of copolymer (C) in dimethylformamide).
Suitable preparation methods for copolymer (C) are as described above for copolymer S1. Preferably as copolymer (C) (=component (C)) a copolymer S1 as described above is used.
Preferably component (D) is present in the molding composition according to the invention in amounts of 2 to 10 wt.-%, more preferably 2.5 to 7 wt.-%, most preferably 3.5 to 7 wt.-%, in particular 4 to 6 wt.-%.
Component (D) is at least one, preferably one, C2 to C8-alkylene-vinylacetate copolymer (D), having a vinylacetate content of more than 25 wt.-%, preferably 25.5 to 30 wt.-%, more preferably 26 to 28 wt.-%.
Preferred as component (D) is an ethylene-vinylacetate (EVA) copolymer having a vinylacetate content of more than 25 wt.-%, preferably 25.5 to 30 wt.-%, more preferably 26 to 28 wt.-%.
Suitable C2-C8-alkylene-vinylacetate copolymers, in particular ethylene-vinylacetate copolymers, which can be used as component (D) are commercially available from Arkema (e.g. Evatane®28-05) or ExxonMobil (e.g. Escorene® Ultra UL 7720, UL 7760).
Various additives and/or processing aids may be used as component (E) for the thermoplastic molding composition according to the invention in amounts of from 0.01 to 10 wt.-%, preferably 0.1 to 10 wt.-%, more preferably 0.3 to 10 wt.-%, most preferably 0.5 to 8 wt.-%.
Suitable additives and/or processing aids (E) include, for example, dyes, pigments, colorants, antistats, antioxidants, stabilizers for improving thermal stability, stabilizers for increasing photostability (=light-stabilizer), stabilizers for enhancing hydrolysis resistance and chemical resistance, anti-thermal decomposition agents, dispersing agents, plasticizers, and in particular external/internal lubricants that are useful for production of molded bodies/articles.
Suitable lubricants/glidants and demolding agents include stearic acids, stearyl alcohol, stearic esters, amide waxes (bisstearylamide, in particular ethylenebisstearamide), polyolefin waxes and/or generally higher fatty acids, derivatives thereof and corresponding fatty acid mixtures comprising 12 to 30 carbon atoms.
Suitable plasticizers are such commonly used for plastics, in particular phthalate-based plasticizers such as bis(2-propylheptyl)phthalate (DPHP). Plasticizers may be used in amounts of up to 5 wt.-%, preferably 0.5 to 3 wt.-%, more preferably 0.7 to 2 wt.-%.
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.
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 the Irganox range. In addition to the phenolic antioxidants cited above by way of example, it is also possible to use so-called costabilizers, in particular phosphorus- or sulfur-containing costabilizers. These phosphorus- or sulfurcontaining costabilizers are known to those skilled in the art.
Examples of suitable stabilizers to counter the effect of light (=light-stabilizer) are various substituted resorcinols, salicylates, benzotriazoles, benzophenones, and HALS (hindered amine light stabilizers), for example those commercially available as Tinuvin® from BASF.
Said light-stabilizers are generally used in amounts up to 5 wt.-%, preferably 0.1 to 2 wt.-%, more preferably 0.3 to 1 wt.-%.
Examples of pigments are titanium dioxide, phthalocyanines, ultramarine blue, iron oxides, and carbon black, in particular carbon black, and the entire class of organic and inorganic pigments.
Said pigments are often used in amounts of 0.01 to 10 wt.-%, preferably 3 to 7 wt.-%.
Preferably component (E) is at least one pigment, light-stabilizer and/or plasticizer.
For further additives and/or processing aids, see, for example, “Plastics Additives Handbook”, H. Zweifel, Hanser Publ., 6th Ed. Munich, 2009.
A further aspect of the invention is a process for the preparation of the thermoplastic molding composition (TP) comprising (consisting of) components (A), (B), (C), (D) and (E) according to the invention which process comprises at least the following steps:
In steps (i) and (iii), graft copolymer GR1 and graft copolymer GR2, respectively, can be used as wet compounds. Optionally, and preferred, in steps (i) and (iii), graft copolymer GR1 and graft copolymer GR2, respectively, are used as dried compounds, more preferably not completely dried compounds (=residual moisture content 18 to 22 wt.-%).
Optionally, prior to step (vi), a step may be carried out, in which a homogenous particulate material mixture is prepared from the components (A) to (E). However, also when provided to the optionally heatable mixing device without previous mixing, in step (vi) a homogenous mixing is typically achieved in the optionally heatable mixing device.
Each of components (A) to (E)—as far as solid—may be provided in form of particulate materials having different particle sizes and particle size distributions (e.g., as pellets, granules and/or powders).
Prior to step (v), in an optional pre-mixing step, components (A) to (E) may be provided to a mixing device (e.g. a high speed mixer) in the required amounts and ratios as previously indicated and optionally pre-mixed in order to obtain a homogenous particulate material mixture. In a preferred embodiment, this may require 1 to 10 minutes, in particular 2 to 5 minutes, depending to the amount of particulate material to be mixed.
Preferably the process according to the invention comprises the afore-mentioned premixing step prior to step (v).
The thus obtained homogenous particulate material mixture of components (A) to (E) is then—in step (v)—transferred to an optionally heatable mixing apparatus and—in step (vi)—blended (melt-mixed) therein, producing a substantially liquid-melt polymer mixture.
“Substantially liquid-melt” means that the polymer mixture, as well as the predominant liquid-melt (softened) fraction, may further comprise a certain fraction of solid constituents, examples being unmelted fillers and reinforcing material such as glass fibers, metal flakes, or else unmelted pigments, colorants, etc. “Liquid-melt” means that the polymer mixture is at least of low fluidity, therefore having softened at least to an extent that it has plastic properties.
Mixing apparatuses used are those known by the person skilled in the art. Components (A) and (B), (C), (D) and—if present—(E) may be mixed, for example, by joint extrusion, kneading, or rolling.
Examples of mixing apparatus for implementing the process include discontinuously operating, heated internal kneading devices with or without RAM, continuously operating kneaders, such as continuous internal kneaders, screw kneaders with axially oscillating screws, Banbury kneaders, furthermore extruders, and also roll mills, mixing roll mills with heated rollers, and calenders.
A preferred mixing apparatus used is an extruder or a kneader. Particularly suitable for melt extrusion are, for example, single-screw or twin-screw extruders. A twin-screw extruder is preferred. In some cases the mechanical energy introduced by the mixing apparatus in the course of mixing is enough to cause the mixture to melt, meaning that the mixing apparatus does not have to be heated. Otherwise, the mixing apparatus is generally heated. Mixing apparatus is operated customarily at 150 to 300° C., preferably 180 to 240° C.
In a preferred embodiment, a heatable twin-screw extruder and a speed of 500 to 600 rpm, preferably 550 rpm, is employed. In a preferred embodiment, an extruding temperature of 170 to 270° C., preferably 210 to 250° C. is employed to obtain the thermoplastic molding composition (TP). The thermoplastic molding composition (TP) may be directly used, e.g. in molding processes, preferably injection molding processes, or may be processed to form granules which may be subjected to molding processes afterwards. The molding processes, in particular injection-molding processes, are preferably carried out at temperatures of 170 to 270° C., in particular 220 to 240° C. to result in a molded or shaped article.
Thus, a further aspect of the invention are shaped articles produced from the thermoplastic molding composition (TP) according to the invention.
Processing 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 or sintering, preferably by injection molding.
A further aspect of the invention is the use of the thermoplastic molding composition according to the invention and of shaped articles made therefrom for applications in the automotive and construction industry.
The invention is further illustrated by the examples and the claims.
Graft copolymer GR1: Acrylate graft copolymer produced as in EP 450485 B1 (page 7, line 11 to 24) with a median weight particle diameter D50 of 95 nm. After drying the residual moisture content of graft copolymer GR1 was 20 wt.-%.
Graft copolymer GR2: Acrylate graft copolymer produced as in EP 450485 B1 (page 7, lines 25 to 38) with a median weight particle diameter D50 of 500 nm. After drying the residual moisture content of graft copolymer GR2 was 20 wt.-%.
Copolymer S1: styrene-acrylonitrile-copolymer (acrylonitrile content: 35 wt.-%) produced by a solution polymerization process; VN: 64 ml/g (DIN 53726 at 25° C. on a 0.5 wt.-% solution of copolymer S1 in dimethylformamide), MVR: 51 ml/10 min (DIN EN ISO 1133-1:2012-03; 220° C./10 kg load).
Copolymer S2: styrene-acrylonitrile-copolymer (acrylonitrile content: 35 wt.-%) produced by a solution polymerization process; VN: 80 ml/g (DIN 53726 at 25° C. on a 0.5 wt.-% solution of copolymer S2 in dimethylformamide), MVR: 16 to 18 ml/10 min (DIN EN ISO 1133-1:2012-03; 220° C./10 kg load).
D-1: random copolymer of ethylene and vinyl acetate (VA content 27 to 28 wt.-%) produced by a high pressure radical polymerization process. Melt flow index: 5 to 8 g/10 min (DIN EN ISO 1133-1:2012-03; 190° C./2.16 kg); melting temperature: ˜72° C. (DIN EN ISO 1183-1:2019-09); density: 0.95 g/cm3 at 23° C. (DIN EN ISO 1183-1:2019-09); commercially available as EVATANE® 28-05 from Arkema.
D-2: random copolymer of ethylene and vinyl acetate (VA content 26.7 wt.-%) produced by a free radical polymerization process. Melt flow index: 5 g/10 min (ASTM D1238, 190° C./2.16 kg); melting temperature: ˜73° C. (DIN EN ISO 1183-1:2019-09); density: 0.951 g/cm3 at 23° C. (ASTM D1505); commercially available as Escorene® Ultra UL 7760 from ExxonMobil.
D-3: random copolymer of ethylene and vinyl acetate (VA content 26.7 wt.-%) produced by a free radical polymerization process. Melt flow index: ˜150 g/10 min (ASTM D1238; 190° C./2.16 kg); melting temperature: ˜66° C. (DIN EN ISO 1183-1:2019-09); density: 0.945 g/cm3 at 23° C. (DIN EN ISO 1183-1:2019-09); commercially available as Escorene® Ultra UL 7720 from ExxonMobil.
E-1—DPHP (Dipropylheptyl phthalate) from AEKYUNG petrochemical, Korea.
E-2—Carbon black masterbatch CB 35 MB (carbon black content: 35 wt.-%; rest: SAN copolymer) from SM Choyang, Korea.
E3—HALS-stabilizer, Tinuvin® 770 from BASF SE, Germany.
In the examples and comparative examples the components were used in the amounts indicated in Tables 1, 3 and 5 below.
The components were mixed in a high-speed mixer for 2 to 3 minutes to attain a good dispersion and uniform pre-mixture for compounding. The obtained pre-mixture was then melt blended in a twin-screw extruder at a screw speed of 550 rpm and using an incremental temperature profile from 180° C. to 240° C. for the different barrel zones.
The extruded strands of the obtained molding composition were water cooled, air-dried and pelletized. This was followed by injection molding of the obtained molding composition to shape the standard test specimens. The temperature profile of the injection molding machine barrel was 220 to 240° C. incremental. The mold temperature was kept at 70° C.
Melt Flow Index (MFI) or Melt Volume Rate (MVR): test was performed (DIN EN ISO 1133-1:2012-03; 220° C./10 kg) for ASA pellets using an MFI machine of CEAST, Italy.
Charpy Impact test: performed on notched specimens (DIN EN ISO 179-1:2010-11, /1 eA) using an Instron, UK impact tester.
Tensile test: carried out at 23° C. (DIN EN ISO 527-1:2019-12) using a Universal testing Machine (UTM) of Instron, UK.
Flexural test: carried out (DIN EN ISO 178:2019-08) at 23° C. using a UTM of Lloyd Instruments, UK.
Heat deflection temperature (HDT): test was performed on injection molded specimen (DIN EN ISO 75-1:2013-08/4 hours annealing of sample at 80° C.) using a Zwick Roell, Germany instrument.
Vicat softening temperature (VST): test was performed on injection molded test specimen (DIN EN ISO 306:2014-03/30 minutes annealing of sample at 80° C.) using a Zwick Roell machine, Germany.
Rockwell Hardness: test was carried out on injection molded test specimen (DIN EN ISO 2039-2:2000-01) using FIE Instruments Pvt Ltd, India.
Whiteness, yellowness and ΔE: measured using Datacolor 850, Switzerland (Measurement condition: D/8°, specular included). The color coordinates and ΔE were measured according to the CIE method. Whiteness and yellowness were measured according to ASTM E313-20.
Gloss measured as per ASTM 02457-13 using a gloss meter of BYK Gardner, Germany. Grey Scale determined as per AATCC/ISO 105-A02:1993. Test specimens are visually compared with standard samples and a rating is given. In the following examples and comparative examples the components were used in the amounts indicated on Tables 1, 3 and 5 below.
Tables 2, 4a and 6 show the properties of the obtained molding compositions.
Table 4b shows the results obtained after weathering of the samples—weathering results
Examples 1 to 8 according to the invention show that the addition of small amounts of EVA reduces the yellowness index of the ASA composition and significantly improves its whiteness.
This is further beneficial as ASA compositions are mostly manufactured pre-colored. The reduction in the yellowness index will consequentially lower the dosage of pigments required to achieve a desired color tone.
Furthermore, the high-flowable molding compositions according to inventive examples 1 to 8 show a significantly improved impact strength (cp. elongation at break and Charpy notched impact strength). Moreover, EVA has been used in such amounts that the complete mechanical properties of the inventive compositions are not deteriorated and the weather resistance characteristics are enhanced.
It has been further shown that the molding compositions according to inventive examples 3 and 4 have an improved gloss and color retention after the weathering test.
The shaped articles produced from the thermoplastic molding composition according to the invention were found to have improved properties.
| Number | Date | Country | Kind |
|---|---|---|---|
| 21181158.3 | Jun 2021 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/066758 | 6/20/2022 | WO |
