Process for obtaining coagulated product

Abstract

The invention relates to a process for obtaining a coagulated product of a polymer, preferably a polymer obtainable by emulsion polymerisation, from an aqueous latex comprising said polymer, comprising a) contacting a coagulant composition with the latex to obtain a slurry and b) removing water from the slurry to obtain the coagulated product, wherein the coagulant composition comprises a first salt selected from salts of a first metal selected from the group consisting of calcium, magnesium, sodium, potassium and zinc and combinations of the salts of the first metal and a second salt selected from aluminum salts.

Description

24POLY0120-WO-ORD 1PROCESS FOR OBTAINING COAGULATED PRODUCTThe present invention relates to a process for obtaining a coagulated product of a polymer from an aqueous latex comprising said polymer.Emulsion polymerisation is a well-reputed process for the production of a variety of polymers, including for example acrylonitrile-butadiene styrene (ABS), styrenebutadiene styrene (SBS), methyl methacrylate-butadiene styrene (MBS), acrylonitrile styrene acrylate (ASA), polytetrafluoroethylene-styrene-acrylonitrile (TSAN) and styrene acrylonitrile (SAN). In such emulsion polymerisation processes, a reaction mixture, and optionally additives for initiation and control of the reaction and emulsifying agent(s) may be combined with a liquid medium, thereby forming an emulsion, which is subjected to conditions for polymerisation. During the polymerisation, a polymeric latex is formed. Such polymeric latex may be understood in the context of the present invention to be a colloidal distribution of polymeric particles in the liquid medium. The liquid medium may for example be water, thereby forming an aqueous dispersion of the polymeric particles.In order to obtain the desired polymer as product from the process, the polymeric particles that are present in the polymeric latex need to be isolated. This can be achieved by a coagulation step. In the coagulation step, the polymeric latex is subjected to certain conditions, optionally including addition of one or more coagulation agents. After coagulation, the polymer can be isolated from the medium, thereby obtaining the desired polymer. This isolation may comprise dewatering and drying.US3896093A describes a process for the recovery of polymers of acrylonitrile and styrene optionally containing butadiene by coagulation of aqueous latices containing these polymers. The process comprises maintaining said aqueous latices in a first coagulation phase in the presence of a coagulant and bringing the aqueous mixture obtained in this way into conditions of boiling or close to boiling in a second coagulation phase. As the coagulant, calcium chloride was used.US2019169320A1 describes a process for the production of a polymer comprising the steps of a) polymerisation of an emulsion or suspension comprising a reaction mixture to obtain a polymeric latex; and b) coagulating the polymeric latex by exposing the polymeric latex to one or more coagulant, and isolating the coagulated product to24POLY0120-WO-ORD 2obtain a polymer, wherein the polymeric latex obtained under a) is stored prior to coagulation step b) for a certain period of time.The isolation step of the coagulated product to obtain the final product is an energy intensive step. It is therefore desirable to obtain a coagulated product which requires less energy for isolation.It is an object of the present invention to provide a process for obtaining a coagulated product of a polymer from an aqueous latex comprising said polymer, which coagulated product requires less energy for isolation.Accordingly, the present invention provides a process for obtaining a coagulated product of a polymer, preferably a polymer obtainable by emulsion polymerisation, from an aqueous latex comprising said polymer, comprisinga) contacting a coagulant composition with the aqueous latex to obtain a slurry and b) removing water from the slurry to obtain the coagulated product,wherein the coagulant composition comprisesa first salt selected from salts of a first metal selected from the group consisting of calcium, magnesium, sodium, potassium and zinc and combinations of the salts of the first metal anda second salt selected from aluminum salts.It was surprisingly found that the coagulated product obtained according to the process of the invention has a low residual moisture content. This advantageously allows use of less energy for dewatering and drying required for isolation.It was further surprisingly found that the coagulated product obtained according to the process of the invention has a low amount of fine powders. Lower amount of fine powders prevents practical difficulties such as blockage of valves and difficulty of filtration and of centrifugation.It is important to note that this process does not use basic reagents such as hydroxides, amines etc., in the coagulation process.Aqueous latexThe present invention provides a process for obtaining a coagulated product of a polymer. In particular, the present invention provides a process for obtaining a24POLY0120-WO-ORD 3coagulated product of a polymer obtainable by emulsion polymerization. The coagulated product is obtained from an aqueous latex comprising said polymer.In the context of the present invention, an aqueous latex may be understood to be an aqueous system comprising polymeric particles in dispersion. The aqueous latex comprising the polymer is obtained by polymerisation of an emulsion or suspension comprising a reaction mixture. Preferably the reaction mixture comprises one or more reactants selected from styrenic, acrylate and vinyl-based monomers, for example the reaction mixture comprises one or more reactants selected from styrene, acrylonitrile, butadiene, polybutadiene, butyl(meth)acrylate, poly(butyl acrylate), methyl(meth)acrylate, or combinations thereof. For example, a latex may comprise 20.0-60.0 wt % of polymeric particles with regard to the total weight of the latex.Preferably, the latex comprises 25.0-55.0 wt % of polymeric particles with regard to the total weight of the latex. More preferably, the latex comprises 30.0-50.0 wt % of polymeric particles with regard to the total weight of the latex.Preferably, the polymer is selected from the group consisting of acrylonitrile-butadiene styrene (ABS), styrene-butadiene styrene (SBS), methyl methacrylate-butadiene styrene (MBS), acrylonitrile styrene acrylate (ASA), polytetrafluoroethylene-styrene-acrylonitrile (TSAN) and styrene acrylonitrile (SAN). Preferably, the polymer is acrylonitrile styrene acrylate (ASA).These polymers are per se well-known. Methods for obtaining aqueous latex comprising these polymers are also well-known and is described in detail e.g. in US2019169320A1

[0012] -

[0056] as described belowThe polymerisation may be performed in one or more polymerisation vessels. Such polymerisation vessel may for example be a closed reactor. The vessel may for example have a volume ranging from 1 I to 75000 I. It may be understood that other vessels and / or vessels having a different volume may also be used for the polymerisation and can be scaled for industrial production of a desired polymer. The vessel can for example have a volume of 3.5 I. The volume of the vessel can refer to the internal volume of the vessel available for occupation by the liquid and vapour containing the applicable reagents. In an example, an initial liquid batch can be introduced into the vessel in an amount sufficient to occupy 40 to 80% of the volume of the vessel.24POLY0120-WO-ORD 4In such polymerisation vessel, an system comprising a medium such as water, a reaction mixture and optionally one or more emulsifying agent(s), may be introduced prior to the onset of the polymerisation reaction. Additionally, additives for initiation and control of the reaction, including for example a free radical initiator, may be introduced.The reaction mixture comprises one or more reactant(s). The reaction mixture may comprise a rubber latex prepared in a previous emulsion reaction. Such rubber latex may be an aqueous dispersion of rubber particles. Such rubber particles may for example be polybutadiene rubber particles. Alternatively, such rubber particles may be acrylate rubber particles. Such rubber particles may for example has an average particle size of 60-500 nm. Preferably, the rubber particles have an average particle size of 150-500 nm. The average particle size may for example be determined according to ASTM D1417 (2010). Rubber particles having such average particle size may be obtained directly from the emulsion reaction, alternatively such rubber particles may be formed by subjecting the rubber latex obtained from the emulsion reaction to a subsequent treatment, such as a chemical or physical agglomeration treatment, to obtain a rubber latex comprising rubber particles having such average particle size.Such rubber latex may for example comprise 20.0-50.0 wt % of rubber particles. More preferably, the rubber latex comprises 25.0-45.0 wt % of rubber particles, with regard to the total weight of the rubber latex.Such rubber latex may be combined with reactants and optionally further ingredients such as additives for initiation and control of the reaction and emulsifying agent(s), as well as optionally a further quantity of the medium to form the reaction mixture.During the course of the polymerisation, further reactants may be provided to the polymerisation vessel. Further, during the course of the polymerisation, a further quantity of a free-radical initiator may be provided to the polymerisation vessel.The polymerisation may be operated in a continuous manner or in a batch-wise manner. In a particular embodiment, the polymerisation is operated in a batch-wise manner.The polymerisation preferably is performed at a pressure of 0-15.0 bar, alternatively 2.0-15.0 bar, alternatively 2.0-10.0 bar, alternatively 2.0-5.0 bar or 2.5-5.0 bar.24POLY0120-WO-ORD 5The polymerisation may for example be performed at a temperature in the range of 35.0-95.0° C., alternatively 50.0-85.0° C. Preferably, the polymerisation is performed at a temperature in the range of 55.0-80.0° C.The polymerisation preferably has a duration of 1.5-9.0 h.It is particularly preferred that the polymerisation is performed at a pressure of 0-15.0 bar, at a temperature in the range of 50.0-85.0° C. More particularly, the polymerisation is performed at a pressure of 2.0-15.0 bar, at a temperature in the range of 50.0-85.0° C. Even more particularly, the polymerisation may be performed at a pressure of 2.0-5.0 bar, at a temperature in the range of 55.0-80.0° C.It is further particularly preferred that the polymerisation is performed at a pressure of 2.0-15.0 bar, at a temperature in the range of 50.0-85.0° C., for a duration of 1.5-9.0 h. More particularly, the polymerisation may be performed at a pressure of 2.0-5.0 bar, at a temperature in the range of 55.0-80.0° C., for a duration of 1.5-9.0 h.Near the end of the polymerisation, a quantity of a further reactant may be introduced to the polymerisation vessel, wherein the further reactant serves to react with the unreacted reactants present in the polymerisation vessel, in order to terminate the polymerisation. Such further reactant may for example be selected from methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, benzyl acrylate, isopropyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, isopropyl methacrylate, cyclohexyl methacrylate, vinyl acetate, dimethyl maleate, diethyl maleate, or combinations thereof. Particularly, the further reactant may be selected from methyl acrylate or methyl methacrylate.Such further reactant may for example be added in a quantity of <5.0 wt %, alternatively <2.0 wt %, alternatively <1.0 wt %, with regard to the total weight of the reaction mixture. Preferably, the further reactant is added in a quantity of >0.5 and <5.0 wt %, alternatively >0.5 and <2.0 wt %, alternatively >0.5 and <1.0 wt %, with regard to the total weight of the reaction mixtureIt is particularly preferred that the polymerisation step comprises the addition of <5.0 wt % with regard to the total weight of the reaction mixture of a further reactant selected from methyl acrylate or methyl methacrylate. It is even more preferred that the polymerisation step comprises the addition of <4.0 or <2.0 wt % with regard to the total24POLY0120-WO-ORD 6weight of the reaction mixture of a further reactant selected from methyl acrylate or methyl methacrylate when the polymerisation reaches 95% conversion. Alternatively, the polymerisation step may comprise the addition of >0.5 and <5.0 wt % with regard to the total weight of the reaction mixture of a further reactant selected from methyl acrylate or methyl methacrylate. More preferably, the polymerisation step comprises the addition of >0.5 and <4.0 wt % or 0.5 and <4.0 wt % with regard to the total weight of the reaction mixture of a further reactant selected from methyl acrylate or methyl methacrylate when the polymerisation reaches 95% conversion.The reactant(s) that are comprised in the reaction mixture may for example be selected from vinyl aromatic compounds, compounds comprising at least 2 unsaturated carboncarbon bonds, polymers obtained from compounds comprising at least 2 unsaturated carbon-carbon bonds, vinyl cyanide compounds, compounds comprising one or more acrylate moieties, polymers obtained from compounds comprising one or more acrylate moieties, or combinations thereof.Suitable vinyl aromatic compounds include for example styrene, a-methyl styrene, halostyrenes such as dibromostyrene, vinyltoluene, vinylxylene, butylstyrene, p-hydroxystyrene, methoxystyrene, or combinations thereof. Particularly suitable vinyl aromatic compounds are for example styrene and a-methyl styrene. It is preferred that the vinyl aromatic compound is styrene.Suitable vinyl cyanide compounds include for example acrylonitrile, methacrylonitrile, ethacrylonitrile, a-chloroacrylonitrile, a-bromoacrylonitrile, or combinations thereof. It is preferred that the vinyl cyanide compound is acrylonitrile.Suitable compounds comprising at least 2 unsaturated carbon-carbon bonds include for example butadiene, isoprene, chloroprene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 1,2-propadiene, 1,4-pentadiene, 1,2-pentadiene, 1,5-hexadiene, or combinations thereof. It is preferred that the compound comprising at least 2 unsaturated carbon-carbon bonds is butadiene.Suitable polymers obtained from compounds comprising at least 2 unsaturated carboncarbon bonds include for example polybutadiene, polyisoprene, poly(styrene-butadiene), poly(acrylonitrile-styrene), poly(styrene-isoprene), poly(isoprene-butadiene), or combinations thereof. It is preferred that the polymer obtained from compounds comprising at least 2 unsaturated carbon-carbon bonds is polybutadiene.24POLY0120-WO-ORD 7Suitable compounds comprising one or more acrylate moieties include for example methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, benzyl acrylate, isopropyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, isopropyl methacrylate, cyclohexyl methacrylate, or combinations thereof. Particularly, the compound comprising one or more acrylate moieties may be selected from methyl acrylate or methyl methacrylate.Suitable polymers obtained from compounds comprising one or more acrylate moieties include for example ethylene acrylic elastomers and poly(n-butyl acrylate).It is preferred that the reactants that are comprised in the reaction mixture are selected from styrene, acrylonitrile, butadiene, polybutadiene, poly(n-butyl acrylate), butyl(meth)acrylate, methyl(meth)acrylate, or combinations thereof. It is particularly preferred that the reactants that are comprised in the reaction mixture include styrene and acrylonitrile. It is further preferred that the reaction mixture comprises polybutadiene. In another particularly preferred embodiment, the reactants that are comprised in the reaction mixture include styrene, polybutadiene and acrylonitrile. Alternatively, the reactants that are comprised in the reaction mixture may include methyl methacrylate, polybutadiene and styrene.The reaction mixture may for example comprise acrylonitrile and styrene, wherein the molar ratio of styrene to acrylonitrile in the reaction mixture is in the range of 1.5-4.0.The reaction mixture may for example comprise acrylonitrile, polybutadiene and styrene, wherein the molar ratio of styrene to acrylonitrile is in the range of 1.5-4.0, and wherein the molar ratio of polybutadiene to the sum of styrene and acrylonitrile is in the range of 0.1 -3.0. It is preferred that reaction mixture comprises acrylonitrile, polybutadiene and styrene, wherein the molar ratio of styrene to acrylonitrile is in the range of 2.0-3.0, and wherein the molar ratio of polybutadiene to the sum of styrene and acrylonitrile is in the range of 0.2-1.0.A particular embodiment of the invention also relates to a process wherein the reaction mixture comprises acrylonitrile, styrene and poly(n-butyl acrylate).During the polymerisation step, a further quantity of reactants may be added to the polymerisation vessel. The composition of this further quantity of reactants may be the24POLY0120-WO-ORD 8same or different from the reactants present in the aqueous system prior to the onset of the polymerisation step. For example, the composition of the further quantity of reactants is the same as of the reactants present in the aqueous system prior to the onset of the polymerisation step.The additives for initiation and control of the reaction may for example include free radical initiators. Suitable free radical initiators include: persulfate compounds such as ammonium persulfate, potassium persulfate and sodium persulfate; peroxides such as hydrogen peroxide, cumene hydroperoxide, t-butyl hydoperoxide, acetylperoxide, lauroyl peroxide, peracetic acid and perbenzoic acid; and azo-compounds such as 2,2'-azobisisobutyronitrile and 4,4'-azobis(4-cyanovaleric acid).The free radical initiators may for example be used in quantities of 0.01-2.00 wt % with regard to the total weight of the reaction mixture, preferably 0.1 -1.5 wt %, more preferably 0.1 -0.5 wt %.The free radical initiators may be provided to the polymerisation at the onset, gradually during the polymerisation reaction, or in one quantity at the onset and a further quantity with the addition of the further reactant.The emulsion may for example be an aqueous emulsion. The emulsion may for example comprise one of more emulsifying agent(s). The emulsifying agent(s) that may be used in the polymerisation step may for example be selected from: anionic emulsifiers including higher fatty alcohol sulphates, higher alkyl sulphonates, alkylaryl sulphonates, aryl sulphonates, the condensation products thereof with formaldehyde, salts of sulphosuccinic acid esters, and suphated ethylene oxide adducts; and non-ionic emulsifiers including the reaction products of ethylene oxide, 2-ethyloxirane or methyloxirane with C10-C20 alkyl alcohol(s); C10-C20 alkyl acid(s); or C10-C20 alkyl amide(s).Such C10-C20 alkyl alcohol(s) may for example be one of more selected from 1 -decanol, 1-dodecanol, 1 -tetradecanol, 1 -hexadecanol, 1-octadecanol or 1-eicosanol.Such C10-C20 alkyl acid(s) may for example be one or more selected from decanoic acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, octadecanoic acid or eicosanoic acid.24POLY0120-WO-ORD 9Such C10-C20 alkyl amide(s) may for example be one or more selected from decanamide, dodecanamide, tetradecanamide, hexadecanamide, octadecanamide or eicosanamide.The emulsifying agent(s) may for example be used in quantities of 0.1 wt %-10.0 wt % with regard to the total weight of the reaction mixture. Preferably, the emulsifying agent(s) may be used in quantities of 0.2 wt %-8.0 wt % with regard to the total weight of the reaction mixture.In some aspects, a chain transfer agent may be added to the polymerisation step. Appropriate chain transfer agents may include for example organic sulfur compounds such as C1-C15 alkyl mercaptans, n-, i- ort-dodecyl mercaptan. The chain transfer agent may be added in quantities of 0.1 -3.0 wt % with regard to the total weight of the reactants, more preferably 0.1 -2.0 wt %.The polymeric latex may for example have a pH of >9.0.Step a)The process according to the invention comprises a) contacting a coagulant composition with the aqueous latex to obtain a slurry.Coagulant compositionThe coagulant composition is understood to contribute to the destabilization of the aqueous dispersion of the polymeric particles in the polymeric latex. The coagulant composition used according to the invention comprises a first salt selected from salts of a first metal selected from the group consisting of calcium, magnesium, sodium, potassium and zinc and combinations of the salts of the first metal and a second salt selected from aluminum salts. The first salt and the second salt used according to the invention are water-soluble.Preferably, the first salt is selected from the group consisting of halides such as chloride or bromide, nitrates, sulfates or acetates of calcium, magnesium, sodium, potassium or zinc and combinations thereof.In preferred embodiments, the first salt comprises or is a calcium salt, i.e. the first metal is calcium.24POLY0120-WO-ORD 10Preferably, the calcium salt is selected from the group consisting of calcium halides and calcium nitrates and combinations thereof.More preferably, the calcium salt is selected from the group consisting of calcium chloride and calcium bromide and combinations thereof.More preferably, the calcium salt comprises calcium chloride, more preferably the calcium salt is calcium chloride.Preferably, the magnesium salt is selected from the group consisting of magnesium halides and magnesium sulfate and combinations thereof, more preferably magnesium chloride and magnesium sulfate and combinations thereof, more preferably magnesium sulfate.Preferably, the sodium salt is selected from the group consisting of sodium halides and sodium sulfate.In preferred embodiments, the first salt is selected from the group consisting of calcium chloride and magnesium sulfate and combinations thereof.Aluminum in the aluminum salt has a valency of +3. Preferably, the aluminum salt is selected from the group consisting of aluminum sulfate, aluminum halides, aluminum nitrates and aluminum acetates and combinations thereof.More preferably, the aluminum salt is selected from the group consisting of aluminum sulfate and aluminum halides and combinations thereof.More preferably, the aluminum salt is selected from the group consisting of aluminum sulfate and aluminum chloride and combinations thereof. Preferably, the aluminum salt comprises or is aluminum sulfate or the aluminum salt comprises or is aluminum chloride.The coagulant composition can comprise one ore more further coagulants.As the optional further coagulants, the coagulant composition can comprise an acid, wherein the acid may be selected from the group consisting of acetic acid, sulfuric acid,24POLY0120-WO-ORD 11nitric acid, phosphoric acid, hydrochloric acid, formic acid, oxalic acid and combinations thereof.The total amount of the first salt and the second salt can e.g. be 90 to 100 wt.% of the total amount of metal salts in the coagulant composition. The total amount of the first salt and the second salt can e.g. be 90 to 100 wt.% of the total coagulant composition. In some preferred embodiments, the coagulant composition consists of the first salt and the second salt.The total amount of the calcium salt and the aluminum salt can e.g. be at least 50 wt.%, e.g. 60 to 100 wt.%, 70 to 100 wt.%, 80 to 100 wt.% or 90 to 100 wt.% of the total amount of metal salts in the coagulant composition. The total amount of the calcium salt and the aluminum salt can e.g. be at least 50 wt.%, e.g. 60 to 100 wt.%, 70 to 100 wt.%, 80 to 100 wt.% or 90 to 100 wt.% of the total coagulant composition. In some preferred embodiments, the coagulant composition consists of the calcium salt and the aluminum salt, preferably the coagulant composition consists of calcium chloride and aluminum sulfate or consists of calcium chloride and aluminum chloride.In particular, the present invention provides a process for obtaining a coagulated product of a polymer, preferably a polymer obtainable by emulsion polymerisation, from an aqueous latex comprising said polymer, comprisinga) contacting a coagulant composition with the aqueous latex to obtain a slurry and b) removing water from the slurry to obtain the coagulated product,wherein the coagulant composition comprises a calcium salt and an aluminum salt.Preferably, the amount (in grams) of aluminum in the coagulant composition with respect to the amount (in kilograms) of solids in the latex is at least 0.10 g / kg, preferably 0.10 to 5.00 g / kg.More preferably, the amount of aluminum in the coagulant composition with respect to the amount of solids in the latex is at least 1.00 g / kg, preferably 1.20 to 1.70 g / kg. This results in a particularly low amount of the residual moisture in the coagulated product.Preferably, the weight ratio of aluminum to the first salt in the coagulant composition is 0.01 to 0.25.24POLY0120-WO-ORD 12Preferably, the first metal is calcium and the weight ratio of aluminum to calcium in the coagulant composition is 0.01 to 0.25.More preferably, the first metal is calcium and the weight ratio of aluminum to calcium in the coagulant composition is 0.10 to 0.20. This results in a particularly low amount of the residual moisture in the coagulated product.Preferably, the amount (in grams) of the first metal with respect to the amount (in kilograms) of solids in the latex is 5.00 to 20.00 g / kg.Preferably, the first metal is calcium and the amount (in grams) of calcium with respect to the amount (in kilograms) of solids in the latex is 5.00 to 20.00 g / kg.Preferably, the slurry obtained by step a) has a pH of at most 5.0, for example 2.5 to 4.0. This results in a particularly low amount of the residual moisture in the coagulated product.Step a) may be performed in a coagulation unit. It is preferred that the coagulant composition is added to the aqueous latex. The coagulation unit may for example be a vessel. The temperature of the content of the coagulation unit during coagulation may for example be 50.0-95.0° C.Step b)The process according to the invention comprises b) removing water from the slurry to obtain the coagulated product. Step b) may be performed e.g. by filtration or centrifugation.As a result of the coagulation process, polymeric particles in the slurry agglomerate and settle at the top or at the bottom of the coagulation unit. The water removal may be performed before and / or after such agglomeration has occurred.The coagulated body obtained by step b) contains particles of the polymer and water and may be in the form of a wet cake. Preferably, the coagulated body obtained by step b) has a moisture content of 10 to 50 wt.%, more preferably 15 to 48 wt.%.24POLY0120-WO-ORD 13The particles of the polymer in the coagulated body have various diameters.Preferably, said particles contain a low amount of fine particles, wherein the fine particles are particles of said polymer having diameters of less than 150 pm.Preferably, the coagulated body comprise particles of the polymer, wherein the amount of particles having diameters of less than 150 pm is less than 10 wt.%, preferably 2.0 to 8.0 wt.%, with respect to the total particles of the polymer in the coagulated body.Step c)The coagulated product may be subjected to drying optionally after washing with water. Powder of the polymer can thereby be obtained.In an aspect, the present invention provides a process for the production of powders of polymer, comprising the steps of:polymerisation of an emulsion or suspension comprising a reaction mixture to obtain an aqueous latex comprising said polymer;a) contacting a coagulant composition with the aqueous latex to obtain a slurry and b) removing water from the slurry to obtain the coagulated product,c) drying the coagulated body to obtain the powders of the polymer,wherein the coagulant composition comprisesa first salt selected from salts of a first metal selected from the group consisting of calcium, magnesium, sodium, potassium and zinc and combinations of the salts of the first metal anda second salt selected from aluminum salts.The polymerisation step to obtain the aqueous latex may be performed according to the methods described in in US2019169320A1

[0012] -

[0056] , described earlier in the section on aqueous latex.The present invention further provides use of a coagulant composition comprising a calcium salt and an aluminum salt for reducing moisture content of a coagulated body of a polymer, preferably a polymer obtainable by emulsion polymerisation, made from an aqueous latex comprising said polymer, preferably wherein the coagulated body has a moisture content of 10 to 50 wt.%.The present invention further provides use of a coagulant composition comprising a calcium salt and an aluminum salt for reducing the amount of fine particles in a24POLY0120-WO-ORD 14coagulated body of a polymer, preferably a polymer obtainable by emulsion polymerisation, made from an aqueous latex comprising said polymer, wherein the fine particles are particles of said polymer having diameters of less than 150 pm.It is noted that the invention relates to the subject-matter defined in the independent claims alone or in combination with any possible combinations of features described herein, preferred in particular are those combinations of features that are present in the claims. It will therefore be appreciated that all combinations of features relating to the composition according to the invention; all combinations of features relating to the process according to the invention and all combinations of features relating to the composition according to the invention and features relating to the process according to the invention are described herein.It is further noted that the term ‘comprising’ does not exclude the presence of other elements. However, it is also to be understood that a description on a product / composition comprising certain components also discloses a product / composition consisting of these components. The product / composition consisting of these components may be advantageous in that it offers a simpler, more economical process for the preparation of the product / composition. Similarly, it is also to be understood that a description on a process comprising certain steps also discloses a process consisting of these steps. The process consisting of these steps may be advantageous in that it offers a simpler, more economical process.When values are mentioned for a lower limit and an upper limit for a parameter, ranges made by the combinations of the values of the lower limit and the values of the upper limit are also understood to be disclosed.The invention is now elucidated by way of the following examples, without however being limited thereto.To a clean 55 gallon vessel, 50 kg of DI water was added along with 925 g of 30% Calcium Chloride (100 g Calcium) and optionally acid or an aluminum salt in an amount shown in Table 1. This mixture was stirred @ 300 rpm and heated to 200 degrees F (93.3 °C). 31.25 kg of ASA latex @ 32% solids was fed at 1000 g / min until all of the latex had been fed. Temperature and agitation were maintained over the course of the addition. Upon completion of the latex addition, the resulting slurry was maintained at 200 degrees F (93.3 °C) for an additionaHO minutes at which time 80 kg of DI water24POLY0120-WO-ORD 15was added. The pH of the slurry after the addition of the latex was measured and are shown in Table 1.The slurry was then transferred to a centrifuge and processed for 5 minutes at 1200 rpm. The resulting wet cake was tested for residual moisture and amount of particles having sizes of less than 150 micrometer. The results are shown in Table 1.Table 1<24POLY0120-WO-ORD 17From comparison of C1 vs C2-C6, it can be understood that the use of an acid to lower the pH of the slurry results in some reduction of the residual moisture. From comparison of C1 vs 11-15, it can be understood that the use of an aluminum salt results in a large reduction of the residual moisture. It can therefore be understood that, while decrease in the pH of the slurry leads to a certain degree of advantageous effects, the use of an aluminum salt is required for large reductions of the residual moisture.Comparison of 11-14 shows that the effect of the moisture reduction is largest when the amount of Al with respect to the weight of solids in latex is at least 1.00 g / kg, particularly 1.20 to 1.70 g / kg.The use of an aluminum salt further results in a reduction of the amount of fine particles.

Claims

24POLY0120-WO-ORD 18CLAIMS1. A process for obtaining a coagulated product of a polymer, preferably a polymer obtainable by emulsion polymerisation, from an aqueous latex comprising said polymer, comprisinga) contacting a coagulant composition with the latex to obtain a slurry and b) removing water from the slurry to obtain the coagulated product,wherein the coagulant composition comprisesa first salt selected from salts of a first metal selected from the group consisting of calcium, magnesium, sodium, potassium and zinc and combinations of the salts of the first metal anda second salt selected from aluminum salts.

2. The process according to any one of the preceding claims, wherein the polymer is selected from the group consisting of acrylonitrile-butadiene styrene (ABS), styrene-butadiene styrene (SBS), methyl methacrylate-butadiene styrene (MBS), acrylonitrile styrene acrylate (ASA), polytetrafluoroethylene-styrene-acrylonitrile (TSAN) and styrene acrylonitrile (SAN).

3. The process according to any one of the preceding claims, wherein the polymer is acrylonitrile styrene acrylate (ASA).

4. The process according to any one of the preceding claims, wherein the first salt comprises or is a calcium salt.

5. The process according to any one of the preceding claims, wherein the slurry obtained by step a) has a pH of at most 5.0, for example 2.5 to 4.0.

6. The process according to any one of the preceding claims, wherein the amount of aluminum in the coagulant composition with respect to the amount of solids in the latex is at least 0.10 g / kg, preferably 0.10 to 5.00 g / kg.

7. The process according to any one of the preceding claims, wherein the weight ratio of aluminum to the first metal in the coagulant composition is 0.01 to 0.25, preferably 0.10 to 0.20, preferably wherein the first metal is calcium.24POLY0120-WO-ORD 198. The process according to any one of the preceding claims, wherein the amount of the first metal with respect to the amount of solids in the latex is 5.00 to 20.00 g / kg, preferably wherein the first metal is calcium.

9. The process according to any one of the preceding claims, wherein the aluminum salt is selected from the group consisting of aluminum sulfate, aluminum halides, aluminum nitrates and aluminum acetates and combinations thereof, preferably the group consisting of aluminum sulfate and aluminum halides and combinations thereof, more preferably the group consisting of aluminum sulfate and aluminum chloride and combinations thereof.

10. The process according to any one of the preceding claims, wherein the coagulated body has a moisture content of 10 to 50 wt.%, preferably 15 to 48 wt.%.

11. The process according to any one of the preceding claims, wherein the coagulated body comprise particles of the polymer, wherein the amount of particles having diameters of less than 150 pm is less than 10 wt.%, preferably 2.0 to 8.0 wt.%, with respect to the total particles of the polymer in the coagulated body.

12. The process according to any one of the preceding claims, wherein step b) involves filtration or centrifugation of the slurry.

13. The process according to any one of the preceding claims, further comprising c) drying the coagulated body to obtain powders of the polymer.

14. Use of a coagulant composition comprising a calcium salt and an aluminum salt for reducing moisture content of a coagulated body of a polymer, preferably a polymer obtainable by emulsion polymerisation, made from an aqueous latex comprising said polymer, preferably wherein the coagulated body has a moisture content of 10 to 50 wt.%.

15. Use of a coagulant composition comprising a calcium salt and an aluminum salt for reducing the amount of fine particles in a coagulated body of a polymer, preferably a polymer obtainable by emulsion polymerisation, made from an aqueous latex comprising said polymer, wherein the fine particles are particles of said polymer having diameters of less than 150 pm.

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