Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08C—TREATMENT OR CHEMICAL MODIFICATION OF RUBBERS
  • C08C1/00—Treatment of rubber latex
  • C08C1/02—Chemical or physical treatment of rubber latex before or during concentration
  • C08C1/065—Increasing the size of dispersed rubber particles
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F279/00—Macromolecular compounds obtained by polymerising monomers on to polymers of monomers having two or more carbon-to-carbon double bonds as defined in group C08F36/00
  • C08F279/02—Macromolecular compounds obtained by polymerising monomers on to polymers of monomers having two or more carbon-to-carbon double bonds as defined in group C08F36/00 on to polymers of conjugated dienes
  • C08F279/04—Vinyl aromatic monomers and nitriles as the only monomers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J3/00—Processes of treating or compounding macromolecular substances
  • C08J3/20—Compounding polymers with additives, e.g. colouring
  • C08J3/201—Pre-melted polymers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J3/00—Processes of treating or compounding macromolecular substances
  • C08J3/20—Compounding polymers with additives, e.g. colouring
  • C08J3/203—Solid polymers with solid and/or liquid additives
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L25/00—Compositions of, homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring; Compositions of derivatives of such polymers
  • C08L25/02—Homopolymers or copolymers of hydrocarbons
  • C08L25/04—Homopolymers or copolymers of styrene
  • C08L25/08—Copolymers of styrene
  • C08L25/12—Copolymers of styrene with unsaturated nitriles
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L55/00—Compositions of homopolymers or copolymers, obtained by polymerisation reactions only involving carbon-to-carbon unsaturated bonds, not provided for in groups C08L23/00 - C08L53/00
  • C08L55/02—ABS [Acrylonitrile-Butadiene-Styrene] polymers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2355/00—Characterised by the use of homopolymers or copolymers, obtained by polymerisation reactions only involving carbon-to-carbon unsaturated bonds, not provided for in groups C08J2323/00 - C08J2353/00
  • C08J2355/02—Acrylonitrile-Butadiene-Styrene [ABS] polymers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2425/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring; Derivatives of such polymers
  • C08J2425/02—Homopolymers or copolymers of hydrocarbons
  • C08J2425/04—Homopolymers or copolymers of styrene
  • C08J2425/08—Copolymers of styrene
  • C08J2425/12—Copolymers of styrene with unsaturated nitriles

Definitions

• the invention relates to a process for the preparation of light-weight ABS (acrylonitrile- butadiene-styrene) molding compositions having a low density and high strength, ABS molding compositions obtained by said process and their use in various applications.
• ABS acrylonitrile- butadiene-styrene
• ABS resins by glass fibers, mineral fillers or in some cases with carbon fibers. This provides good enhancements of mechanical prop erties of ABS resins but the density of the ABS composition is considerably increased.
• CN-A 102746606 discloses modified ABS materials filled with hollow glass microbeads comprising: 50 to 80 wt.-% of ABS resin (no details about composition), 3 to 5 wt.-% of a compatibilizer, 5 to 10 wt.-% of a toughener (e.g. hydrogenated SBS styrene-based thermoplastic elastomer), 3 to 5 wt.-% of a silane coupling agent, 1 to 3 wt.-% of a rein- forcing agent (ultrafine silica) , 5 to 30 wt.-% of hollow glass beads (i.e. soda lime boro- silicate), and 1 to 3 wt.-% of plastic processing assistants.
• ABS resin no details about composition
• a compatibilizer e.g. hydrogenated SBS styrene-based thermoplastic elastomer
• a silane coupling agent e.g. hydrogenated SBS styrene-based thermoplastic e
• styrene maleic anhydride graft copolymer As compatibilizer, a styrene maleic anhydride graft copolymer (S-g-MAH) is used.
• the ABS material is obtained by first premixing the ABS resin, compatibilizer and coupling agent in a blender or mixer, then all other components (including the hollow glass beads) are added and mixing is continued, and the obtained mixed material is melt-blended in a twin-screw extruder.
• the ABS material is used for instruments and household-applications; light weight applica tions are not mentioned.
• WO 2015/162242 discloses a foamed light weight styrene polymer composition for au- tomotive applications comprising: A) 40 to 88% by weight of an ABS and/or ASA resin, B) 5 to 30% by weight of hollow glass microspheres (i.e. soda lime borosilicate, particle size (diameter) 5 to 50 pm), C) 0.1 to 2.5% by weight of a chemical foaming agent, D) 1 to 5% by weight of a compatibilizer (e.g. a styrene-acrylonitrile grafted maleic anhydride copolymer), E) 5 to 20% by weight of an impact modifier, and F) optionally 0.1 to 3% by weight of a plastic processing aid.
• a compatibilizer e.g. a styrene-acrylonitrile grafted maleic anhydride copolymer
• E 5 to 20% by weight of an impact modifier
• F optionally 0.1 to 3% by weight of a plastic processing aid.
• the ABS resin is a mixture of graft copoly mer A1) - a diene based rubber onto which a copolymer of styrene and acrylonitrile is grafted - with 40 to 85 wt.-% of a rubber free styrene-acrylonitrile copolymer A2).
• the material is obtained by melt mixing all components, except of the hollow glass beads, in a twin-screw extruder, and then the hollow glass beads are added by a side-feeder in a zone of the extruder after the kneading section.
• One object of the invention is to provide a process for the preparation of light weight thermoplastic molding compositions which allows a trouble-free feeding and minimizes the crushing of the hollow-glass beads. It was surprisingly found that the problem can be solved by the process according to the claims.
• thermoplastic molding composition comprising (or consisting of) components (A), (B), (C), (D) and, if pre sent, (E):
• copolymer (B) 30.5 to 80 wt.-% of at least one copolymer (B) of styrene and acrylonitrile in a weight ratio of from 81:19 to 65:35, it being possible for styrene and/or acrylonitrile to be partially (less than 50 wt.-%) replaced by methyl methacrylate, alpha-methyl styrene and/or 4-phenylstyrene, preferably alpha-methyl styrene; wherein copoly mer (B) has a weight average molar mass M w of 90,000 to 145,000 g/mol;
• component (i) Premixing of a portion of 2 to 10 wt.-%, preferably 3 to 8 wt.-%, of component (A) with the hollow glass microspheres (D); (ii) Mixing and melting of the remaining portion of component (A), components (B), (C) and, if present, (E), in the feeding section of an extruder, preferably a twin-screw extruder;
• thermoplastic molding composition (TP) additive of the pre-mixture obtained in step (i) to the melt obtained in step (ii) by a side-feeder in a zone of the extruder after the kneading section to obtain the thermoplastic molding composition (TP) by melt mixing.
• Wt.-% means percent by weight.
• the median weight particle diameter D 50 also known as the D 50 value of the integral mass distribution, is defined as the value at which 50 wt.-% of the particles have a diam eter smaller than the D 50 value and 50 wt.-% of the particles have a diameter larger than the D 50 value.
• the weight-average particle diameter D w in particular the me dian weight particle diameter D50, is determined with a disc centrifuge (e.g.: CPS Instru ments Inc., DC 24000 with a disc rotational speed of 24000 rpm).
• the weight-average particle diameter D w is defined by the following formula (see G. Lagaly, O. Schulz and R. Ziemehl, Dispersionen und Emulsionen: Neue Einchtung in die Kolloidik feinverteilter Stoffe einschlieBlich der Tonminerale, Darmstadt: Steinkopf-Verlag 1997, ISBN 3-7985 -1087-3, page 282, formula 8.3b):
• D w sum ( n, * di 4 ) / sum( n, * d, 3 ) n, is number of particles of diameter d,.
• the summation is 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 which is the case for the starting rubber latices and agglomerated rub ber latices the volume average particle size diameter Dv is equal to the weight average particle size diameter Dw.
• the weight average molar mass M w is determined by GPC (solvent: tetrahydrofuran, polystyrene as polymer standard) with UV detection according to DIN 55672-1:2016-03.
• step (ii) of the process according to the invention a mixture of the remaining portion of component (A), components (B), (C) and, if pre sent, (E) is prepared and premixed - for example in a high speed mixer or extruder - to obtain a uniformly mixed material.
• step (iii) of the process according to the invention the molding composition obtained in step (iii) is extruded via a die plate and the extruded polymer strands are cooled, preferably water cooled, and pelletized.
• step (i) of the process according to the invention a portion of 3 to 8 wt.-% of component (A), more preferably a portion of 4 to 6 wt.-% of component (A), - based on the total component (A) - is used.
• the used components are mixed for 1 to 5 minutes, more preferably 2 minutes, at an average speed of 250 to 1000 rpm, more preferably 450 to 550 rpm, in particular 500 rpm, to obtain a pre-mixture.
• step (i) of the process according to the invention Due to this premixing in step (i) of the process according to the invention the crushing of the hollow glass microspheres (D) is minimized during the melt mixing in step (iii).
• the melt mixing in steps (ii) and (iii) is generally done at temperatures in the range of from 160°C to 300°C, preferably from 180°C to 280°C, more preferably 215°C to 250°C.
• Said temperatures ensure the complete melting of the entire component (A) and a trou ble-free feeding.
• a twin-screw extruder is used. More preferably a twin screw extruder having high channel depth conveying elements is used to avoid breaking of the hollow glass beads (D).
• the high channel depth defined by the OD/ID ratio is preferably 1.3 to 1.8 more preferably approximately 1.55.
• a particular suit able extruder has 9 heating zones, usually in zones 1 , 2, 5, 6 and 8 are the high channel width/volume conveying elements, and usually in zones 3 and 4, in particular in more than half of zones 3 and 4, are kneading sections. In zone 1 (feeding section), the re maining portion of component (A), components (B), (C) and, if present, (E) is fed and passed through a set of kneading blocks to ensure its complete melt mixing.
• thermoplastic molding composition (TP) obtained by the process according to the invention. It is preferable that the thermoplastic molding composition (TP) comprises (or consists of):
• thermoplastic molding composition comprises (or consists of):
• thermoplastic molding composition comprises (or con sists of):
• Graft copolymer (A) (component (A)) is known and described in WO 2012/022710. Graft copolymer (A) consists of 15 to 60 wt.-% of a graft sheath (A2) and 40 to 85 wt.-% of a graft substrate - an agglomerated butadiene rubber latex - (A1), where (A1) and (A2) sum up to 100 wt.-%.
• graft copolymer (A) is obtained by emulsion polymerization of styrene and acrylonitrile in a weight ratio of 80:20 to 65:35 to obtain a graft sheath (A2), it being possible for styrene and/or acrylonitrile to be replaced partially (less than 50 wt.-%, pref erably less than 20 wt.-%, more preferably less than 10 wt.-%, based on the total amount of monomers used for the preparation of (A2)) by alpha-methylstyrene, methyl methac rylate or maleic anhydride or mixtures thereof, in the presence of at least one agglomer ated butadiene rubber latex (A1).
• This rubber latex has a median weight particle diameter Dsoof 200 to 800 nm, preferably 225 to 650 nm, more preferably 250 to 600 nm, most preferred 280 to 350 nm, in par ticular 300 to 350 mm.
• the at least one, preferably one, graft copolymer (A) consists of 20 to 50 wt.-% of a graft sheath (A2) and 50 to 80 wt.-% of a graft substrate (A1).
• graft copolymer (A) consists of 30 to 45 wt.-% of a graft sheath (A2) and 55 to 70 wt.-% of a graft substrate (A1).
• graft copolymer (A) consists of 35 to 45 wt.-% of a graft sheath (A2) and 55 to 65 wt.-% of a graft substrate (A1).
• the obtained graft copolymer (A) has a core-shell-structure; the graft substrate (a1) forms the core and the graft sheath (A2) forms the shell.
• styrene and acrylonitrile are not partially replaced by one of the above-mentioned co-monomers; preferably styrene and acrylonitrile are polymerized alone in a weight ratio of 95:5 to 50:50, preferably 80:20 to 65:35.
• the at least one, preferably one, starting butadiene rubber latex (S-A1) preferably has a median weight particle diameter D50 of equal to or less than 110 nm, particularly equal to or less than 87 nm.
• butadiene rubber latex means polybutadiene latices produced by emulsion polymerization of butadiene and less than 50 wt.-% (based on the total amount of mon omers used for the production of polybutadiene polymers) of one or more monomers that are copolymerizable with butadiene as comonomers.
• Examples for such monomers include isoprene, chloroprene, acrylonitrile, styrene, al pha-methylstyrene, Ci-C4-alkylstyrenes, Ci-Cs-alkylacrylates, Ci-Cs-alkylmethacrylates, alkyleneglycol diacrylates, alkylenglycol dimethacrylates, divinylbenzol; preferably, buta diene is used alone or mixed with up to 30 wt.-%, preferably up to 20 wt.-%, more pref erably up to 15 wt.-% styrene and/or acrylonitrile, preferably styrene.
• the starting butadiene rubber latex (S-A1) consists of 70 to 99 wt.-% of buta diene and 1 to 30 wt.-% styrene. More preferably the starting butadiene rubber latex (S- A1) consists of 85 to 99 wt.-% of butadiene and 1 to 15 wt.-% styrene. More preferably the starting butadiene rubber latex (S-A1) consists of 85 to 95 wt.-% of butadiene and 5 to 15 wt.-% styrene.
• the agglomerated rubber latex (graft substrate) (A1) is obtained by agglomeration of the above-mentioned starting butadiene rubber latex (S-A1) with preferably at least one acid anhydride, more preferably acetic anhydride or mixtures of acetic anhydride with acetic acid, in particular acetic anhydride.
• graft copolymer (A) is described in detail in WO 2012/022710. It can be prepared by a process comprising the steps: a) synthesis of starting butadiene rubber latex (S-A1) by emulsion polymerization, b) agglomeration of latex (S-A1) to obtain the agglomerated butadiene rubber latex (A1) and y) grafting of the agglomerated butadiene rubber latex (A1) to form a graft copolymer (A).
• the synthesis (step a) of starting butadiene rubber latices (S-A1) is described in detail on pages 5 to 8 of WO 2012/022710.
• the starting butadiene rubber latices (S-A1) are produced by an emulsion polymerization process using metal salts, in particular persulfates (e.g. potassium persulfate), as an initiator and a rosin-acid based emulsifier.
• metal salts in particular persulfates (e.g. potassium persulfate), as an initiator and a rosin-acid based emulsifier.
• resin or rosin acid-based emulsifiers those are being used in particular for the production of the starting rubber latices by emulsion polymerization that contain alkaline salts of the rosin acids.
• Salts of the resin acids are also known as rosin soaps. Examples include alkaline soaps as sodium or potassium salts from disproportionated and/or dehydrated and/or hydrated and/or partially hydrated gum rosin with a content of dehydro- abietic acid of at least 30 wt.-% and preferably a content of abietic acid of maximally 1 wt.-%.
• alkaline soaps as sodium or potassium salts of tall resins or tall oils can be used with a content of dehydroabietic acid of preferably at least 30 wt.-%, a content of abietic acid of preferably maximally 1 wt.-% and a fatty acid content of preferably less than 1 wt.-%.
• Mixtures of the aforementioned emulsifiers can also be used for the production of the starting rubber latices.
• alkaline soaps as sodium or potassium salts from disproportionated and/or dehydrated and/or hydrated and/or partially hydrated gum rosin with a content of dehydroabietic acid of at least 30 wt.-% and a content of abietic acid of maximally 1 wt.-% is advantageous.
• the emulsifier is added in such a concentration that the final particle size of the starting butadiene rubber latex (S-A1) achieved is from 60 to 110 nm (median weight particle diameter D50).
• Polymerization temperature in the preparation of the starting rubber latices (S-A1) is generally 25°C to 160°C, preferably 40°C to 90°C. Further details to the addition of the monomers, the emulsifier and the initiator are described in WO 2012/022710. Molecular weight regulators, salts, acids and bases can be used as described in WO 2012/022710.
• step b) the obtained starting butadiene rubber latex (S-A1) is subjected to agglomeration (step b)) to obtain an agglomerated rubber latex (A1).
• the agglomeration may be carried out as described on pages 8 to 12 of WO 2012/022710, said method is preferred.
• acetic anhydride more preferably in admixture with water, is used for the ag glomeration.
• the agglomeration step b) is carried out by the addition of 0.1 to 5 parts by weight of acetic anhydride per 100 parts of the starting rubber latex solids.
• the agglomerated rubber latex (A1) is preferably stabilized by addition of further emul sifier while adjusting the pH value of the latex (A1) to a pH value (at 20°C) between pH 7.5 and pH 11, preferably of at least 8, particular preferably of at least 8.5, in order to minimize the formation of coagulum and to increase the formation of a stable agglomer ated rubber latex (A1) with a uniform particle size.
• further emulsifier preferably rosin- acid based emulsifiers as described above in step step a) are used.
• the pH value is adjusted by use of bases such as sodium hydroxide solution or preferably potassium hydroxide solution.
• the obtained agglomerated latex rubber latex (A1) has a median weight particle diame ter Dsoof generally 200 to 800 nm, preferably 225 to 650 nm, more preferably 250 to 600 nm, most preferred 280 to 350 nm, in particular 300 to 350 nm.
• the obtained agglomer ated latex rubber latex (A1) preferably is mono-modal.
• step y the agglomerated rubber latex (A1) is grafted to form the graft copolymer (A).
• Suitable grafting processes are described in detail on pages 12 to 14 of WO 2012/022710.
• Graft copolymer (A) is obtained by emulsion polymerization of styrene and acrylonitrile - optionally partially replaced by alpha-methylstyrene, methyl methacrylate and/or ma leic anhydride - in a weight ratio of 95:5 to 50:50 to obtain a graft sheath (A2) (in partic ular a graft shell) in the presence of the above-mentioned agglomerated butadiene rub ber latex (A1).
• graft copolymer (A) has a core-shell-structure.
• the grafting process of the agglomerated rubber latex (A1) of each particle size is pref erably carried out individually.
• the graft polymerization is carried out by use of a redox catalyst system, e.g. with cumene hydroperoxide or tert.-butyl hydroperoxide as preferable hydroperoxides.
• a redox catalyst system e.g. with cumene hydroperoxide or tert.-butyl hydroperoxide as preferable hydroperoxides.
• any reducing agent and metal component known from literature can be used.
• a preferred grafting process which is carried out in presence of at least one agglomerated butadiene rubber latex (A1) with a median weight particle diameter Dsoof preferably 280 to 350 nm, more preferably 300 to 330 nm, in an initial slug phase 15 to 40 wt.-%, more preferably 26 to 30 wt.-%, of the total monomers to be used for the graft sheath (A2) are added and polymerized, and this is followed by a controlled addition and polymerization of the remaining amount of monomers used for the graft sheath (A2) till they are consumed in the reaction to increase the graft ratio and improve the conversion.
• Component (B) is preferably a copolymer of styrene and acry lonitrile.
• Copolymer (B) has preferably a melt flow index (MFI) of 60 to 70 g/10 min (ASTM D1238).
• MFI melt flow index
• the weight average molar mass M w of copolymer (B) generally is 90,000 to 145,000 g/mol, preferably 95,000 to 130,000 g/mol, more preferably 100,000 to 115,000 g/mol.
• thermoplastic molding composition (TP) copolymer (C) is generally comprised in an amount of 1.5 to 9.5 wt.-%, preferably 2 to 8 wt.-%, more preferably 3 to 5 wt.-%, most preferably 4 to 5 wt.-%.
• copolymer (C) comprises structural units derived from maleic imide, in partic ular N-phenyl maleic imide, and/or maleic anhydride.
• Copolymers (C) often comprise structural units derived from maleic imide and/or maleic anhydride in an amount of from 1 to 30 wt.-%, preferably 6 to 12 wt.-%, more preferably 8 to 10 wt.-%.
• Copolymer (C) functions as a compatibilizing agent between the glass reinforcing agents (components D and E) and the matrix polymer by improving the bonding of the hollow glass beads and the glass fibers to the matrix polymer phase.
• copolymer (C) is selected from the group consisting of: styrene-maleic anhydride copolymers, styrene-acrylonitrile-maleic anhydride-terpolymers, styrene-N- phenyl maleic imide-copolymers and styrene-acrylonitrile-N-phenyl maleic imide-terpol- ymers.
• styrene-acrylonitrile-maleic anhydride terpolymers are particularly preferred.
• styrene-acrylonitrile-maleic anhydride terpolymers comprising struc- tural units derived from maleic anhydride in an amount of 8 to 10 wt.-%.
• copolymer (C) The preparation of copolymer (C) is commonly known. It can be advantageously pre pared by mass (bulk) or solution polymerization by a continuous free radical polymeriza tion process.
• Copolymer (C) has preferably a melt flow index (MFI) in the range of 90 to 110 g/10 min (ASTM D1238).
• MFI melt flow index
• the weight average molar mass M w of copolymer (C) is generally in the range of from 80,000 to 145,000 g/mol, preferably in the range of from 90,000 to 100,000 g/mol.
• the hollow glass microspheres or hollow glass beads (HGB) used as component (D) comprise inorganic materials which are typically used for glasses such as e.g. silica, alumina, zirconia, magnesium oxide, sodium silicate, soda lime, borosilicate etc.
• the hollow glass beads comprise soda lime borosilicate, which is commercially available.
• the hollow glass beads are preferably mono-modal.
• the hollow glass beads have a particle size (median weight particle diameter D50) in the range of from 15 to 60 pm, preferably 18 to 40 pm, more preferably 18 to 25 pm.
• the glass beads are of the thin wall type having preferably a wall thickness of 0.5 to 1.5 pm.
• the hollow glass microspheres generally have a true density of from 0.40 to 0.60 g/cm 3 , preferably 0.40 to 0.50 g/cm 3 . Their bulk density is preferably in the range of from 0.25 to 0.35 g/cm 3 , in particular 0.25 to 0.30 g/cm 3 .
• the hollow glass microspheres preferably have a compressive strength in the range of 100 to 140 MPa, in particular 105 to 120 MPa.
• component (E) If component (E) is present, its minimum amount is 0.01 wt.-%, based on the entire ther moplastic molding composition (TP).
• thermoplastic molding composition (TP) in amounts of from 0.01 to 15 wt.-%, preferably 0.05 to 10 wt.-%, more preferably 0.05 to 5 wt.-%, as assis tants and processing additives.
• Suitable additives and/or processing aids include, for example, dyes, pigments, col orants, antistats, antioxidants, stabilizers for improving thermal stability, stabilizers for increasing photostability, stabilizers for enhancing hydrolysis resistance and chemical resistance, anti-thermal decomposition agents, dispersing agents, flow modifiers and surface energy enhancer, and in particular external/internal lubricants that are useful for production of molded bodies/articles.
• step (ii) of the process according to the invention are admixed in step (ii) of the process according to the invention, in order to profit early from the stabilizing effects (or other specific ef fects) of the added substance.
• Suitable lubricants/glidants and demolding agents include stearic acids, stearyl alcohol, stearic esters, amide waxes (bisstearylamide, in particular ethylenebisstearamide), pol yolefin waxes and/or generally higher fatty acids, derivatives thereof and corresponding fatty acid mixtures comprising 12 to 30 carbon atoms.
• antioxidants examples 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.
• antioxidants 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 sulfur- containing costabilizers are known to those skilled in the art.
• Suitable flow modifiers and surface energy enhancer comprise at least one oligomeric or polymeric compound having at least one functional group selected from the group consisting of ester groups, siloxane groups, epoxy groups, anhydride groups, carboxyl groups, acrylate groups, and nitrile groups.
• a preferred flow modifier and surface energy enhancer is for example a mixture of a di ester of sebacic acid and glycidyl epoxy alkoxy siloxane.
• pigments are titanium dioxide, phthalocyanines, ultramarine blue, iron ox ides, and carbon black, and the entire class of organic and inorganic pigments.
• Dyes are any of the dyes which can be used for the transparent, semitransparent, or non-transparent coloring of polymers, in particular those dyes which are suitable for coloring styrene copolymers. Dyes of this type are known to the skilled worker. Said pigments and dyes may be used in amounts up to 10 wt.-%, preferably up to 5 wt.-%.
• One preferred pigment is carbon black (e.g. from Cabot Corp., USA).
• component (E) is at least one lubricant, antioxidant, flow modifier and surface energy enhancer and/or pigment.
• thermoplastic molding composition obtained by the process according to the invention.
• Said shaped articles can be obtained by known processes for thermoplastic processing, in particular preferred is injection molding.
• thermoplastic molding compositions (TP) obtained by the process according to the invention are lightweight compositions having a reduced specific gravity and good me chanical properties such as tensile and flexural properties.
• thermoplastic molding composition (TP) obtained by the process according to the invention or of shaped articles produced there from for various applications, in particular in the auto-(mobile), white goods or - in espe cially - electronic industry.
• thermoplastic molding composition (TP) or of shaped articles produced therefrom for electronic devices where a high endur ance and fatigue resistance is required (e.g. fan blades).
• the weight average particle size Dw (in particular the median weight par ticle diameter D50) with the disc centrifuge DC 24000 by CPS Instruments Inc. equipped with a low density disc
• an aqueous sugar solution of 17.1 ml_ with a density gradient of 8 to 20% by wt. of saccharose in the centrifuge disc was used, in order to achieve a stable flotation behavior of the particles.
• a polybutadiene latex with a narrow distribution and a mean particle size of 405 nm was used for calibration.
• the measurements were carried out at a rotational speed of the disc of 24,000 r.p.m. by injecting 0.1 ml_ of a diluted rubber dispersion into an aqueous 24% by wt. saccharose solution.
• the calcula tion of the weight average particle size Dw was performed by means of the formula
• D w sum ( n, * di 4 ) / sum( n, * d, 3 ) n,: number of particles of diameter d,.
• Molar Mass M w The weight average molar mass M w is determined by GPC (solvent: tetrahydrofuran, polystyrene as polymer standard) with UV detection according to DIN 55672-1 :2016-03.
• MFI Melt Flow Index
• MFR Melt Volume Flow Rate
• Impact test Izod impact tests were performed on notched specimens (ASTM D 256 standard) using an instrument of CEAST (part of Instron’s product line), Italy.
• Tensile test carried out at 23°C (ASTM D 638, 5 mm/min and 50 mm/min) using a Uni versal testing Machine (UTM) of Instron, UK.
• Flexural test was carried out at 23°C (ASTM D 790, 5 mm/min) using a UTM of Instron, UK.
• Heat deflection temperature test was performed on injection molded specimen (ASTM D 648, at 1.82 MPa, annealed) using a Zwick Roell machine, Germany.
• VST test was performed on injection molded test specimen (ASTM D 1525-09 standard) using a Zwick Roell machine, Germany. Test was carried out at a heating rate of 120°C/h (Method B) at 50 N load.
• the fine-particle butadiene rubber latex (S-A1) which is used for the agglomeration step was produced by emulsion polymerization using tert-dodecyl-mercaptan as chain trans- fer agent and potassium persulfate as initiator at temperatures from 60° to 80°C. The addition of potassium persulfate marked the beginning of the polymerization. Finally the fine-particle butadiene rubber latex (S-A1) was cooled below 50°C and the non reacted monomers were removed partially under vacuum (200 to 500 mbar) at temperatures below 50°C which defines the end of the polymerization.
• the bu tadiene rubber latex (S-A1) is characterized by the following parameters, see table 1.
• Latex S-A1-1 No seed latex is used.
• the potassium salt of a disproportionated rosin (amount of potassium dehydroabietate: 52 wt.-%, potassium abietate: 0 wt.-%) and as salt tetrasodium pyrophosphate is used.
• S salt amount in percent relative to the weight of solids of the rubber latex
• the production of the coarse-particle, agglomerated butadiene rubber latices (A1) was performed with the specified amounts mentioned in table 2.
• the fine-particle butadiene rubber latex (S-A1) was provided first at 25°C and was adjusted if necessary with deionized water to a certain concentration and stirred.
• an amount of acetic anhydride based on 100 parts of the solids from the fine-particle butadiene rubber latex (S-A1) as fresh produced aqueous mixture with a concentration of 4.58 wt.-% was added and the total mixture was stirred for 60 seconds.
• graft copolymer (A) 59.5 wt.-parts of mixtures of the coarse-particle, agglomerated butadiene rubber latices A1-1 and A1-2 (ratio 50 : 50, calculated as solids of the rubber latices (A1)) were diluted with water to a solid content of 27.5 wt.-% and heated to 55°C. 40.5 wt.-parts of a mixture consisting of 72 wt.-parts styrene, 28 wt.-parts acrylonitrile and 0.4 wt.-parts tert-dodecyl- mercaptan were added in 3 hours 30 minutes.
• the graft rubber latex was stabilized with ca. 0.6 wt.-parts of a phenolic antioxidant and precipi- tated with sulfuric acid, washed with water and the wet graft powder was dried at 70°C (residual humidity less than 0.5 wt.-%).
• Component (B) Statistical copolymer (B) from styrene and acrylonitrile with a ratio of polymerized sty rene to acrylonitrile of 72:28 with a weight average molecular weight Mw of 110,000 g/mol, and a MFI at 220°C/10kg of 61 g/10 minutes, produced by free radical solution polymerization.
• Component (C) Statistical copolymer (B) from styrene and acrylonitrile with a ratio of polymerized sty rene to acrylonitrile of 72:28 with a weight average molecular weight Mw of 110,000 g/mol, and a MFI at 220°C/10kg of 61 g/10 minutes, produced by free radical solution polymerization.
• Component (C) Statistical copolymer (B) from styrene and acrylonitrile with a ratio of polymerized sty rene to acrylonitrile of 72
• Fine-Blend ® SAM-010 (terpolymer of styrene, acrylonitrile and maleic anhydride, with 8 ⁇ 2 wt.-% maleic anhydride, Mw 90,000 to 100,000 g/mol) from Fine-blend Compatilizer Jiangsu Co., LTD, China.
• Hollow glass microspheres - having a true density of 0.46 g/cm 3 , a bulk density of 0.28 g/cm 3 and a compressive strength of 110 MPa, particle diameter (D50) 20 pm - com- pitchally available as iM16K from 3M India.
• thermoplastic compositions Preparation of thermoplastic compositions
• step (i) of the inventive process a portion of 5 wt.-% of component (A) was premixed with the hollow glass microspheres (HGS, component (D)) for 2 minutes at an average speed of 500 rpm in a mixer. Then, the remaining portion (95 wt.-%) of compo- nent (A), components (B), (C) and (E) were premixed for 2 to 3 minutes at an average speed of 2200 rpm in a high speed mixer to obtain a uniform pre-mixture.
• the uniform pre-mixture of components (A), (B), (C) and (E) prepared was extruded through a twin-screw extruder.
• the extruder has co-rotating screws and has a separating feeding hopper (side feeder) after the kneading section, for feeding the pre-mixture with the HGS obtained in step (i).
• the pre-mixture of components (A), (B), (C) and (E) was melt blended in said twin-screw extruder at a screw speed of 350 rpm and using an incremental temperature profile from 215° C to 250° C for the different barrel zones.
• the pre-mixture with the HGS obtained in step (i) was separately fed during compounding through said side feeder of the extruder.
• the extruded reinforced polymer blend strands were water cooled, air-dried and pelletized.
• comparative example 1 The preparation of comparative example 1 was carried out as afore-mentioned but with out step (i) wherein component (D) with a portion of component (A) is mixed and dry- blended. Component (D) was added to the side-feeder solely (without a portion of component (A)).
• Table 1 Reinforced ABS compositions The test data of the obtained ABS compositions are shown on Table 2.
• the mechanical properties, especially tensile strength and flexural strength, of the light weight thermoplastic molding compositions obtained by the process according to the invention show better results.
• a better reduction in density is achieved (cp. specific gravity).
• the STDEV of the example according to the invention is insignificant and proves a bet ter distribution and consistency of the hollow glass microspheres (HGS) in the molding composition compared to comparative example 1 which STDEV is significantly higher and which properties are probably impaired due to the improper distribution of the HGS filler.
• Figure 1 shows on the left the surface of a sample according to example 2 and on the right the surface of a sample according to comparative example 1.
• Figure 2 shows a microscopic image (scale-up 12.5 times) of a sample according to example 2.
• Figure 3 shows a microscopic image (scale-up 12.5 times) of a sample ac cording to comparative example 1.
• thermoplastic molding compositions e.g. by injection molding

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• 2022
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