Poly(meth)acrylate impact modifiers having improved optical properties and methods for their preparation - Patents.com

Abstract

The present invention is directed to a poly(meth)acrylate impact modifier comprising at least one multiphase alkyl(meth)acrylate emulsion polymer containing at least one polyvalent metal ion selected from, for example, alkaline earth metals, zinc and aluminum, and a defined amount of alkali metal ions, wherein the impact modifier or molding composition produced therefrom has improved optical properties, particularly high transparency after hot water storage. The impact modifier comprises no more than 3.0 mmol / kg of alkali metal ion based on the solids content of the impact modifier, and exhibits a molar ratio of alkali ion to polyvalent metal ion of no more than 1.3.

Description

[Technical field]

[0001] The present invention is directed to a poly(meth)acrylate impact modifier comprising at least one multiphase alkyl(meth)acrylate emulsion polymer containing at least one polyvalent metal ion selected from, for example, alkaline earth metals, zinc and aluminum, and a defined amount of alkali metal ions, wherein the impact modifier or molding composition produced therefrom has improved optical properties, particularly high transparency after hot water storage. The impact modifier comprises no more than 3.0 mmol / kg of alkali metal ion based on the solids content of the impact modifier, and exhibits a molar ratio of alkali ion to polyvalent metal ion of no more than 1.3.

[0002] The present invention is further directed to a process for the preparation of poly(meth)acrylate impact modifiers, comprising the preparation of at least one multiphase alkyl(meth)acrylate polymer by emulsion polymerization, coagulation and mechanical dehydration of the resulting latex, in which the amount of alkali ions and polyvalent metal ions, typically coming from coagulants and other auxiliary agents, in the dehydrated alkyl(meth)acrylate emulsion polymer is controlled.

[0003] The present invention also relates to impact-modified molding compositions, in particular impact-modified poly(methyl methacrylate) (PMMA) compositions, having an improved property profile, including good optical properties, in particular high transparency after hot water storage. The molding compositions are preferably used to produce molded articles and semi-finished products, such as films and sheets, in particular transparent articles and semi-finished products, or products with good optical appearance.

[0004] Background technology It is known that the impact resistance of relatively brittle synthetic resins, such as molding compositions, especially poly(meth)acrylate molding compositions, can be improved by incorporating an appropriate amount of so-called impact modifiers. It is an established practice in the industry to use impact modifiers produced by emulsion polymerization, known as core, core-shell or core-shell-shell particles. These generally comprise an elastomeric phase, for example as the core or as an intermediate shell grafted to the core, and a hard outer phase, which typically ensures good incorporation of the impact modifier particles into the matrix polymer. Such multiphase emulsion polymers and their preparation are described, for example, in WO 2004 / 056893.

[0005] Typically, such impact modifiers produced by emulsion graft polymerization are obtained as aqueous polymer dispersions (latexes) and must be post-processed by coagulation and isolation of the emulsified polymer. Several methods of coagulation (also called precipitation) of polymer latexes are well known and described in the prior art.

[0006] In general, it is described that emulsified polymers, such as the poly(meth)acrylate impact modifiers of the present invention, can be coagulated by known physical coagulation processes, such as shear coagulation, thermal shear coagulation, spray drying, freeze coagulation or pressure coagulation processes, or by chemical coagulation processes involving the addition of electrolytes, particularly polyvalent cations, such as alkaline earth metal salts, aluminum salts or zinc salts, or inorganic or organic acids.

[0007] For example, coagulation of aqueous polymer dispersions by continuous or semi-continuous freeze-coagulation and subsequent mechanical dewatering, for example using a centrifugation step, is described in WO 2015 / 074883. Coagulation and dewatering of emulsion polymers by thermal shear coagulation in an extruder line is described, for example, in WO 02 / 184539, EP 0683028 and EP 0187715. EP 0467288 describes that acrylic molded products containing acrylic polymer freeze-coagulated materials show better extrusion stability compared to coagulated materials obtained by spray drying or using common chemical coagulants such as aluminum chloride, sodium chloride, magnesium sulfate or sulfuric acid.

[0008] In many cases, the process of coagulation and dewatering of emulsion polymers, especially in extruder systems, suffers from the problem that the separated aqueous phase often has an undesirably high polymer concentration. This is particularly disadvantageous, since it leads to high loads on purification plants (chemical oxygen demand (COD value)) and losses of polymer product during wastewater treatment. Therefore, there is a need to provide an improved method that leads to a reduction in the polymer concentration in the separated aqueous phase and in the wastewater.

[0009] Another common method for coagulating emulsion polymers is to mix the emulsion polymer (latex) with a coagulant, which is often selected from aqueous solutions of metal salts, especially divalent or trivalent metal ions, and / or acids such as sulfuric acid, acetic acid, phosphoric acid, etc. For example, aqueous solutions of alkali metal salts, alkaline earth metal salts, zinc salts or aluminum salts, such as magnesium sulfate, calcium chloride and aluminum chloride, are used as coagulants.

[0010] The document JP 03-247603 A describes a process for coagulating a latex of a graft polymer, in which the latex and a conventional coagulant are mixed in a co-rotating twin screw kneader. The coagulant may be selected, for example, from sodium chloride, calcium chloride, magnesium chloride, sodium sulfate, magnesium sulfate, some carbonates, aluminum salts and acids. The coagulant may be added to the process in an amount of 0.05 to 50% by weight, based on the solid content of the polymer latex. The latex polymer may be, for example, a graft copolymer of butyl acrylate grafted with methyl methacrylate. The amount of alkali metal ions or alkaline earth metal ions in the dehydrated graft polymer is not described in JP 03-247603 A.

[0011] Japanese Patent Application Laid-Open Publication No. 2000-119476 describes an acrylic multi-layered polymer obtained by coagulating an emulsion polymer latex using a coagulant, in which the amount of residual cations derived from the coagulant is 200 ppm or less. The coagulant is typically selected from magnesium sulfate, calcium chloride, and aluminum sulfate. Typically, coagulation is performed by mixing the emulsion polymer latex with an aqueous solution of magnesium sulfate, calcium chloride, or aluminum sulfate. The acrylic multi-layered polymer is composed of a hard outer layer containing methacrylate ester units and a soft inner layer containing acrylate ester units. For emulsion polymerization of the acrylic multi-layered polymer, known anionic surfactants such as sodium stearate, sodium myristate, sodium dioctyl sulfosuccinate, sodium dodecylbenzenesulfonate, sodium dodecylbenzenesulfonate, and sodium lauryl sulfate can be used. JP 2000-119476 A describes washing the coagulated polymer until the desired amount of magnesium ions or calcium ions is obtained. The amount of alkali metal ions or the ratio of alkali metal ions to alkaline earth metal ions in the dehydrated graft polymer is not described in JP 2000-119476 A.

[0012] The document JP 2005-171141 A describes a latex with improved dehydration behavior, containing a multilayer structure polymer suitable for use as a modifier, film or molding material. The latex of JP 2005-171141 A has a solid content of 35-42% by weight, and the multilayer polymer particles in the latex exhibit a mass average particle size of 0.100-0.770 μm. Furthermore, JP 2005-171141 A describes a method for coagulating and coating a multilayer polymer from a latex, in which the coagulation is carried out by contacting the latex with an aqueous solution of a coagulant such as sulfuric acid, hydrochloric acid, calcium chloride, magnesium sulfate, calcium formate and calcium acetate. Furthermore, the addition of a buffer containing an alkali metal or an alkaline earth metal is described. For example, calcium acetate is added as a coagulant in an amount of 1.0-4.0% by weight based on 100 parts by weight of the solid content of the multilayer polymer latex. The formation of scale (i.e. calcium carbonate deposits) is determined by filtering the multi-layer polymer latex through a 150 μm metal mesh and collecting the scale from the inner wall of the polymerization reactor. The amount of alkali metal salts or alkaline earth metal salts in the dehydrated polymer or in the final polymer product is not described in JP 2005-171141 A.

[0013] Document EP 0187715 describes a method for coagulating an aqueous polymer latex by contacting the aqueous polymer latex with an aqueous solution of a water-soluble, non-nucleophilic, non-oxidizing alkaline earth metal and / or zinc salt and recovering the coagulated polymer. The coagulant is used in an effective amount of 0.05 of 5% by weight based on the weight of the latex polymer solids. For example, calcium acetate, calcium hypophosphite are used as coagulants. For example, the polymer latex is contacted with the coagulant in an extruder that includes a coagulation zone, a dewatering zone and a devolatilization zone. It is stated that the process of EP 0187715 should improve the water haze value, yellowness index and light transmission. The amount of alkali metal salt or alkaline earth metal salt in the dehydrated polymer or in the final polymer product is not described in EP 0187715.

[0014] Document EP 0 465 049 describes blends of poly(methyl methacrylate) with heterogeneous core / shell polymers having an alkyl acrylate polymer stage and an alkyl methacrylate polymer shell, where the color of the polymer blend should be improved if the core / shell polymer is treated with a phosphorus-containing reducing agent. In particular, EP 0 465 049 discloses the addition of sodium hypophosphite or calcium hypophosphite to the emulsified polymer before solidification by freeze-drying or spray-drying. For example, the hypophosphite reducing agent is added in an amount of 0.025-0.10%, calculated on a solid / solid basis. However, the amount of alkali metal salt or alkaline earth metal salt in the dehydrated polymer or in the final impact modifier is not described in these examples. Furthermore, EP 0465049 describes a dry blend of PMMA matrix polymer, impact modifier powder, and sodium hypophosphite, where the amount of sodium hypophosphite (NaH2PO2) is 50-200 ppm relative to the polymer blend (matrix polymer / impact modifier=1:1).

[0015] Document EP 2189497 A1 relates to a polymer composition comprising a multi-stage copolymer and a phosphate of a multivalent cation, in particular added for the coagulation of the multi-stage copolymer latex, and an alkaline phosphate of 100 ppm or more, calculated as phosphorus on the dry multi-stage copolymer. In particular, EP 2189497 A1 describes the preparation and coagulation of a multi-stage graft copolymer having a crosslinked butadiene / styrene core, and the coagulated and washed multi-stage graft copolymer is treated with disodium hydrogen phosphate (Na2HPO4), which is added in excess relative to the calcium ions, so that no calcium chloride remains and all calcium ions are present in the form of calcium phosphate. After said treatment, the multi-stage graft copolymer is dried and incorporated in a polycarbonate molding composition as an impact modifier in an amount of 5% by weight. As a result, said multi-stage copolymer contains a large amount of sodium ions.

[0016] The document EP 3747914 A1 describes a multi-layer acrylic polymer coagulum characterized by its bulk density, particle size, and the amount of alkali and alkaline earth metals N (mmol / kg) is defined by the formula Σ(N / a)*(120-Tg)≦100 based on the glass transition temperature Tg (° C.) of the acetone soluble portion of the coagulum, and the valence a of the alkali and alkaline earth metals. The multi-layer acrylic polymer coagulum of D1 will exhibit excellent transparency, resistance to hot water whitening and stress whitening.

[0017] The document EP 2942360 describes a thermoplastic resin powder obtained by coagulating a polymer latex produced by emulsion polymerization using a phosphoric ester as an emulsifier, the content of free acid in the resin being 500 ppm or less. EP 2942360 describes that the amount of coagulant should be as low as possible, since the presence of polyvalent metal ions in the thermoplastic resin powder reduces the flowability of the thermoplastic resin powder. The thermoplastic resin powder is described as containing less than 50 ppm calcium, preferably less than 50 ppm calcium and magnesium in total, and 60 to 300 ppm aluminum, and more than 50 ppm phosphorus. For example, aluminum sulfate or sulfuric acid is used as the coagulant. The amount of alkali metal ions is not discussed in EP 2942360.

[0018] The document GB 2226324(A) describes a transparent, viscous molding composition comprising 10-90% of a hard phase made of methyl methacrylate and 1-90% of a viscous phase distributed in the hard phase, for example made of a crosslinked butyl acrylate polymer, the molding composition comprising not more than 0.05% by weight of water-soluble components. It is described that the aqueous phase is separated in liquid form from the coagulate to such an extent that not more than 0.05% by weight of water-soluble components remain in the composition in order to ensure permanent transparency, especially under the influence of moisture.

[0019] Document WO 2013 / 160029 describes a polymer composition containing at least a graft polymer B1 produced by emulsion polymerization, and optionally a thermoplastic polymer A, a rubber-free vinyl (co)polymer, and other polymers or polymer additives. The emulsion graft copolymer is precipitated in a basic medium with at least one alkaline earth metal salt, and comprises at least one sodium salt and at least one alkaline earth metal salt with a molar ratio Na / (Mg+Ca) of at least 0.10 and at most 1.0. It is stated that the molded body prepared from said emulsion graft copolymer B1 should have an improved surface quality after storage under hot and humid conditions. WO 2013 / 160029 teaches reducing the amount of alkaline earth metal salts originating from the coagulation agent and, if necessary, increasing the amount of sodium by adding sodium salts, for example sodium phosphate, during the emulsion polymerization and / or coagulation process. The examples of WO 2013 / 160029 disclose a precompound of 50 wt. % acrylonitrile / butadiene / styrene (ABS) emulsion graft copolymer and thermoplastic styrene / acrylonitrile copolymer (SAN), the ABS emulsion graft copolymer containing potassium ions in an amount of 130 or 100 ppm and sodium ions in an amount of 35 or 110 ppm. WO 2013 / 160029 does not describe emulsion graft copolymers having an alkali metal ion content of less than 3 mmol / kg.

[0020] Particularly important properties of impact-modified PMMA molding compositions are advantageous mechanical properties such as high toughness (impact resistance, notched impact resistance), high elasticity (modulus of elasticity), as well as good processability (thermoplastic flowability, MVR), as well as good weathering and heat resistance. Furthermore, a fundamental requirement imposed on PMMA molding compositions and articles is that they are optically transparent, even after exposure to high temperatures or hot water. In general, products considered to be optically transparent are those with a haze value of less than or equal to 15.0%, in particular less than 10.0%, very particularly less than 6.0%, as measured by a BYK Gardner Hazegard-plus haze meter, measured at 23°C on test specimens with a thickness of 1 mm according to standard ASTM D1003 (2013).

[0021] Impact modified PMMA molding compositions and articles made therefrom often suffer from reduced transparency and milky white color after storage in hot water, especially after 10-24 hours in water at 80° C. Thus, there is a great need to provide impact modified PMMA molding compositions that exhibit reduced haze and high light transmission after hot water storage.

[0022] Summary of the Invention One object of the present invention is to provide poly(meth)acrylate impact modifiers, as well as molding compositions, moldings and semi-finished products, such as films and sheets, which contain poly(meth)acrylate impact modifiers, with improved optical properties, in particular with high transparency and high transmission. In particular, the impact modifiers should produce lower haze values, measured at 23°C on test pieces having a thickness of 1 mm according to standard ASTM D1003 (2013), in comparison with prior art modifiers, in particular after hot water storage at 70°C and 80°C. Furthermore, the impact modifiers should show high light transmission values, even after hot water storage at 70°C to 80°C, for example for 4 to 24 hours. In particular, it is an object of the present invention to obtain semi-finished products, preferably transparent semi-finished products, with an ASTM 1003-13 haze of less than 30%, preferably less than 20%, in particular after hot water storage at 70°C, preferably at 80°C, for example for 4 to 24 hours.

[0023] Another object of the present invention is to provide a cost-effective and easy process for producing poly(meth)acrylate impact modifiers and / or impact-modifying polymer compositions. In particular, the object of the present invention is to facilitate and optimize the separation of the polymer from the aqueous phase, resulting in a reduced polymer content in the wastewater from the dewatering.

[0024] Means for solving the problem Surprisingly, it has been found that when the amount of alkali ions in the impact modifier, especially after solidification and dehydration, is reduced below a critical value of about 3.0 mmol / kg, preferably below 2.5 mmol / kg, more preferably below 2.0 mmol / kg, based on the dry impact modifier, and at the same time the molar ratio of alkali ions to polyvalent metal ions, preferably selected from alkaline earth metals, zinc and aluminum, is adjusted to 1.3 or less, preferably 1.2 or less, the haze of the impact modifier or transparent articles made therefrom after hot water storage is reduced.Furthermore, typically, the impact modifier of the present invention or test pieces containing it show high light transmission values ​​even after hot water storage.

[0025] Typically, said alkali metal ions originate from additives such as emulsifiers, initiators and buffers used in emulsion polymerization. In general, the salt content in the coagulated polymer can be reduced by washing and / or a higher degree of dehydration. In this connection, it has been surprisingly found that such a desired low amount of alkali metal ions can be obtained by adding a polyvalent metal ion salt, such as an alkaline earth metal salt (e.g. calcium acetate or calcium hydroxide) or an aluminum salt, before or during coagulation, rather than after coagulation. In particular, it has been found that the combination of a specified maximum amount of alkali metal ions and a minimum amount of polyvalent metal ions, such as alkaline earth metal ions or aluminum ions, typically added before the coagulation of the emulsion polymer, improves the hot water storage stability of the impact modifier. Furthermore, a preferred minimum amount of polyvalent metal ions of 0.5 mmol / kg or more, preferably 2.0 mmol / kg, is advantageous.

[0026] Furthermore, it has been found that when certain values ​​of alkali metal ions and molar ratios of alkali ions to multivalent metal ions in the dehydrated polymer are met, the amount of polymer in the wastewater formed by the separated aqueous phase is significantly reduced.

[0027] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is directed to a poly(meth)acrylate impact modifier (hereinafter also referred to as impact modifier) ​​comprising (preferably consisting essentially of) at least one multiphase alkyl(meth)acrylate emulsion polymer (hereinafter also referred to as emulsion polymer), comprising at least one polyvalent metal ion and an alkali metal ion in an amount of 3.0 mmol / kg or less, preferably 2.5 mmol / kg or less, more preferably 2.0 mmol / kg or less, based on the solids content of the impact modifier, wherein the molar ratio (in the poly(meth)acrylate impact modifier) ​​of alkali ion to polyvalent metal ion, preferably selected from alkaline earth metals, zinc and aluminium, is 1.3 or less, preferably 1.2 or less.

[0028] Typically, the metal ions contained in the impact modifier of the present invention originate from the auxiliary agents, such as initiators, surfactants and buffer salts, used in the emulsion polymerization process of the multiphase alkyl (meth)acrylate emulsion polymer. Typically, a significant amount of the metal ions in the impact modifier originate from the coagulant used in the isolation of the emulsion polymer from the aqueous latex dispersion. In addition, the metal ions may originate from additives, such as stabilizers, added to the impact modifier. In particular, the alkali metal ions contained in the impact modifier of the present invention originate from the initiator and / or surfactant used in the emulsion polymerization. In particular, the multivalent ions, such as alkaline earth metal ions, contained in the impact modifier of the present invention originate from the coagulant containing at least one salt of multivalent metal ions, such as alkaline earth metal salt, added before coagulation.

[0029] The term "polyvalent metal" or "polyvalent metal ion" refers to a metal ion having two or more ionic charges, preferably two or three. Preferably, the polyvalent metal ion can be selected from metals in IUPAC Group 2 (alkaline earth metals) and IUPAC Groups 8-14, more preferably from metals in IUPAC Group 2 (alkaline earth metals), IUPAC Group 12 (zinc group) and IUPAC Group 13 (boron group).

[0030] The term "alkali metals" or "alkali metal ions" includes elements in IUPAC Group 1 of the Periodic Table of the Elements, particularly lithium (Li), sodium (Na) and potassium (K). The term "alkaline earth metals" or "alkaline earth metal ions" includes elements in IUPAC Group 2 of the Periodic Table of the Elements, particularly magnesium (Mg), calcium (Ca), strontium (Sr) and barium (Ba).

[0031] As used herein, the term "(meth)acrylate" is meant to include methacrylates, acrylates, and mixtures thereof.

[0032] The term "alkyl (meth)acrylate polymer" means a polymer that contains at least 30% by weight, preferably at least 40% by weight, and more preferably at least 50% by weight, of alkyl (meth)acrylate monomer units, including copolymers of alkyl (meth)acrylate monomers with one or more other copolymerizable monomers.

[0033] The term "alkyl (meth)acrylate emulsion polymer" means a multiphase emulsion polymer comprising at least 30% by weight, preferably at least 40% by weight, and more preferably at least 50% by weight, of alkyl (meth)acrylate monomer units in an outer shell, which may comprise a copolymer of alkyl (meth)acrylate monomers with one or more other copolymerizable monomers, such as styrene.

[0034] The terms "aqueous" or "aqueous solution" mean that the medium or solvent consists of or contains water as a major component. For example, a polar water-miscible co-solvent, such as an alcohol, may be included in the medium or solvent.

[0035] The term "latex" as used in connection with the present invention means a water-insoluble polymer dispersed in an aqueous phase, preferably stabilized by one or more surfactants, and prepared by conventional polymerization techniques, preferably emulsion polymerization.

[0036] Unless otherwise defined, the term ppm means mg / kg according to the present invention, for example, the term ppm means mg / kg of solids of the poly(meth)acrylate impact modifier.

[0037] The content of metal ions, such as alkali metals and polyvalent metal ions, such as alkaline earth metals, in emulsion polymers or impact modifiers is typically determined by atomic emission spectroscopy after chemical digestion of polymer samples, for example microwave-assisted digestion of polymer samples in nitric acid. The amount of alkali metals and polyvalent metals, such as alkaline earth metals or aluminum, is typically given taking into account the detection limit of the respective analytical method. For example, an amount given as 0% by weight or 0 mmol / kg is understood to be below the detection limit of the respective analytical method.

[0038] Preferably, the at least one polyvalent metal ion is selected from metal ions from IUPAC Group 2 (alkaline earth metals), IUPAC Group 12 (zinc group) and IUPAC Group 13 (boron group). More preferably, the polyvalent metal ion is selected from alkaline earth metals, preferably magnesium (Mg) and / or calcium (Ca), and metals from IUPAC Group 13, preferably aluminum. Most preferably, the polyvalent metal ion is selected from alkaline earth metals, zinc (Zn) and aluminum (Al). In a further preferred embodiment, the at least one polyvalent is selected from magnesium (Mg), calcium (Ca), zinc (Zn) and aluminum (Al), more preferably magnesium (Mg), calcium (Ca) and aluminum (Al).

[0039] In a preferred embodiment, the alkali metal ions are selected from sodium and potassium ions and the at least one multivalent ion is selected from alkaline earth metals, aluminum and zinc, more preferably calcium, magnesium and aluminum.

[0040] In particular, the amount of alkali metal ions refers to the sum of all alkali metal ions present in the poly(meth)acrylate impact modifier. In particular, the amount of polyvalent metal ions, such as alkaline earth metal ions and / or aluminum ions, refers to the sum of all polyvalent metal ions, such as alkaline earth metal ions and / or aluminum ions, present in the poly(meth)acrylate impact modifier. Preferably, the alkali metal ions are sodium ions and / or potassium ions, and the amount of alkali metal ions refers to the sum of sodium ions and potassium ions. Preferably, the polyvalent metal ions are magnesium ions, calcium ions and / or aluminum ions, and the amount of polyvalent metal ions refers to the sum of magnesium ions, calcium ions and aluminum ions.

[0041] The at least one alkali metal ion and at least one polyvalent metal ion, such as an alkaline earth metal ion or an aluminum ion, may be present in the impact modifier in any form, such as a solid salt, or in the form of a salt-containing entity dissolved in the aqueous phase and bound or adsorbed to other components or groups of the emulsion polymer, such as anionic groups.

[0042] Preferably, the poly(meth)acrylate impact modifier comprises 0-3.0 mmol / kg, preferably 0-2.5 mmol / kg, more preferably 0-2 mmol / kg, also preferably 0.01-3.0 mmol / kg, also preferably 0.01-2.0 mmol / kg of alkali metal ions based on the solids content of the impact modifier.

[0043] Preferably, the poly(meth)acrylate impact modifier comprises 0.5 to 20.0 mmol / kg, preferably 1.0 to 10.0 mmol / kg, more preferably 2.0 to 8.0 mmol / kg of polyvalent metal ions, such as alkaline earth metal ions and / or aluminum ions, based on the solids content of the impact modifier.

[0044] Preferably, the poly(meth)acrylate impact modifier comprises not more than 3.0 mmol / kg, preferably not more than 2.5 mmol / kg, of alkali metal ions, based on the solids content of the impact modifier, and at least one polyvalent metal ion, based on the solids content of the impact modifier, of not less than 0.5 mmol / kg, preferably not less than 1.0 mmol / kg, more preferably not less than 2.0 mmol / kg, also preferably not less than 3.0 mmol / kg.

[0045] In certain preferred embodiments, the poly(meth)acrylate impact modifier comprises 0 to 3.0 mmol / kg, preferably 0 to 2.5 mmol / kg, also preferably 0.01 to 3.0 mmol / kg, particularly preferably 0.1 to 2.0 mmol / kg of alkali metal ions, based on the solids content of the impact modifier, and 0.5 to 20.0 mmol / kg, preferably 1.0 to 10.0 mmol / kg, more preferably 2.0 to 8.0 mmol / kg of polyvalent metal ions, such as alkaline earth metal ions and / or aluminum ions, based on the solids content of the poly(meth)acrylate impact modifier.

[0046] In the impact modifier of the present invention, the molar ratio of alkali ions to multivalent ions (e.g. alkaline earth metal ions and / or aluminum ions) is not more than 1.3, preferably not more than 1.2, preferably not more than 1.0, more preferably not more than 0.8, more preferably not more than 0.7. Particularly preferably, the molar ratio of alkali ions to multivalent ions (e.g. alkaline earth metal ions and / or aluminum ions) is in the range of 0 to 1.3, also preferably in the range of 0.01 to 1.3, more preferably in the range of 0.1 to 1.3.

[0047] In particular, in the impact modifier of the present invention, the molar ratio of polyvalent ions (e.g. alkaline earth metal ions and / or aluminum ions) to alkali ions is 0.8 or more, preferably 0.9 or more, also preferably 1.0 or more, more preferably 2.0 or more. Particularly preferably, the molar ratio of polyvalent ions (e.g. alkaline earth metal ions and / or aluminum ions) to alkali ions is in the range of 0.8 to 20, preferably in the range of 0.9 to 10.

[0048] In a preferred embodiment, the poly(meth)acrylate impact modifier comprises sodium and / or potassium ions in an amount of 3.0 mmol / kg or less, preferably 2.5 mmol / kg or less, also preferably 2.0 mmol / kg or less, based on the solids content of the impact modifier, and magnesium, calcium and / or aluminum ions in an amount of 1.0 mmol / kg or more, preferably 2.0 mmol / kg or more, also preferably 3.0 mmol / kg or more, based on the solids content of the impact modifier. Typically, the amounts refer to the sum of the alkali metal ions or the sum of the magnesium, calcium and / or aluminum ions, respectively, present in the impact modifier.

[0049] Typically, the impact modifier comprises or essentially consists of polymer particles prepared by emulsion polymerization. After emulsion polymerization, said impact modifier is in the form of an aqueous polymer dispersion at the end of the synthesis process. This aqueous polymer dispersion, also called latex, contains not only the polymer fraction but also polar water-soluble auxiliary materials such as surfactants, buffer substances, initiators and other redox components necessary to carry out the polymerization process.

[0050] Multiphase alkyl (meth)acrylate emulsion polymer Preferably, the multiphasic alkyl (meth)acrylate emulsion polymer is an emulsion polymer obtained by emulsion polymerization, preferably by sequential emulsion polymerization, of alkyl (meth)acrylate monomers and optionally other copolymerizable monomers, the emulsion polymer having a multiphasic structure comprising at least one core and at least one, preferably one or two shells.

[0051] For example, the multiphase alkyl (meth)acrylate emulsion polymer may be formed by crosslinked particles having a core-shell structure or a core-shell-shell structure. Typically, the particles have an average particle size of 20 nm to 500 nm, preferably 50 nm to 450 nm, more preferably 100 nm to 400 nm, most preferably 150 nm to 350 nm. The average particle size can be determined by methods known to those skilled in the art, for example by static or dynamic light scattering, such as laser diffraction measurements or photon correlation spectroscopy according to DIN ISO 13321:1996. Typically, the volume average particle size can be obtained from light scattering measurements.

[0052] In a preferred embodiment, the multiphasic alkyl (meth)acrylate emulsion polymer comprises a soft elastomeric core and a hard non-elastomeric outer phase, typically produced in the presence of the core by graft emulsion polymerization. Said multiphasic alkyl (meth)acrylate emulsion polymer is hereinafter referred to as a core-shell emulsion polymer. For example, the soft elastomeric core may be a crosslinked C1-C olefin such as polybutadiene, or crosslinked polybutyl acrylate. 10 It may be based on an alkyl acrylate polymer.

[0053] In another preferred embodiment, the multiphasic alkyl (meth)acrylate emulsion polymer comprises a hard, non-elastomeric core, a soft, elastomeric intermediate shell formed in the presence of the core, typically by graft emulsion polymerization, and a hard, non-elastomeric outer shell formed in the presence of the intermediate core-shell particles, typically by graft emulsion polymerization, said multiphasic alkyl (meth)acrylate emulsion polymer being hereinafter referred to as a core-shell-shell emulsion polymer.

[0054] Preferably, the outer shell of the multiphase emulsion polymer is a hard phase comprising at least 70% by weight, more preferably at least 80% by weight, of at least one C1-C6 alkyl methacrylate, preferably at least 70% by weight, more preferably at least 80% by weight, of methyl methacrylate, relative to the outer shell.

[0055] Preferably, at least 50% by weight, more preferably at least 55% by weight, more preferably at least 80% by weight of the outer layer, based on the total weight of the emulsion polymer, is covalently bonded to the soft phase, i.e., the soft core of the core-shell emulsion polymer or the intermediate shell of the core-shell-shell emulsion polymer. Typically, the amount of covalently bonded outer layer (grafted polymer) (also called the degree of grafting) is determined as the amount insoluble in acetone.

[0056] To determine the degree of grafting, the water of the emulsion polymer dispersion is removed in a drying cabinet to obtain the pure modifier solid. 1.5 g of the multiphase emulsion polymer is mixed with 40 g of acetone and stirred at 40 °C until a turbid solution is obtained (2-3 h). The insoluble grafted polymer is separated by centrifugation (e.g., 9000 rpm, 2-5 h) and the clear supernatant is dried to a constant weight to obtain the amount of the soluble fraction. This allows the calculation of the degree of grafting by applying equation (1). Grafting degree = 100% - acetone solubles (1)

[0057] Preferably, the degree of grafting of the emulsion polymer is in the range of 50 to 100% by weight, preferably 52 to 99% by weight, based on the solid content of the emulsion polymer.

[0058] Preferably, the alkyl (meth)acrylate emulsion polymer comprises at least 60% by weight, preferably at least 75% by weight, of at least one C1-C alkyl (meth)acrylate copolymer based on the total emulsion polymer. 20 Alkyl (meth)acrylates, more preferably methyl methacrylate and / or n-butyl acrylate.

[0059] Generally, the (meth)acrylate is a C1-C 10 -Alkyl (meth)acrylate, C2-C 20 -Alkenyl (meth)acrylate, C6-C 20 Aryl (meth)acrylate, C6-C 20 Aralkyl (meth)acrylates, C1-C 10Included are hydroxyalkyl (meth)acrylates, glycol di(meth)acrylates, and multifunctional (meth)acrylates.

[0060] Preferably, the emulsion polymer is at least one C1-C 10 an alkyl methacrylate, preferably at least one C1-C methacrylate selected from methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, pentyl methacrylate, hexyl methacrylate, heptyl methacrylate, octyl methacrylate, isooctyl methacrylate, and ethylhexyl methacrylate; 10 These include alkyl methacrylates, as well as cycloalkyl methacrylates such as cyclohexyl methacrylate.

[0061] Preferably, the emulsion polymer is at least one C1-C 10 at least one C1-C alkyl acrylate selected from methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, pentyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, isooctyl acrylate, and ethylhexyl acrylate; 10 These include alkyl acrylates, as well as cycloalkyl acrylates such as cyclohexyl acrylate.

[0062] In particular, the multi-phase alkyl (meth)acrylate emulsion polymer is At least 10% by weight, preferably at least 20% by weight, preferably 10 to 70% by weight of at least one of C1 to C 10 , preferably a C1 to C6 alkyl methacrylate, preferably methyl methacrylate; 5 to 80% by weight, preferably 20 to 80% by weight, of at least one of C1 to C 10an alkyl acrylate (preferably n-butyl acrylate) or at least one conjugated diene (preferably butadiene); 0 to 2% by weight, preferably 0.1 to 2% by weight, more preferably 0.5 to 1% by weight of at least one crosslinkable monomer, preferably a polyfunctional (meth)acrylate and / or an allyl (meth)acrylate; 0 to 15% by weight, preferably 0.5 to 10% by weight, more preferably 0.5 to 5% by weight, optionally further monomers, preferably different from the above mentioned monomers, such as vinyl aromatic monomers, e.g. styrene, α-methylstyrene or benzyl methacrylate, preferably styrene; The composition comprises (preferably consists of)

[0063] The amounts are given relative to the total mass of the monomers.

[0064] More specifically, the multi-phase alkyl (meth)acrylate emulsion polymer comprises: At least 40% by weight, preferably 40 to 70% by weight, of at least one of C1 to C 10 , preferably a C1 to C6 alkyl methacrylate, preferably methyl methacrylate; 5 to 45% by weight, preferably 20 to 45% by weight, preferably 25 to 42% by weight of at least one of C1 to C 10 Alkyl acrylate, preferably C1-C6 alkyl acrylate, preferably C1-C6 alkyl acrylate selected from ethyl acrylate, methyl acrylate, 2-ethylhexyl acrylate and butyl methacrylate (more preferably C1-C 10 Alkyl acrylates include n-butyl acrylate) and 0 to 2% by weight, preferably 0.1 to 2% by weight, more preferably 0.5 to 1% by weight of at least one crosslinkable monomer, preferably a polyfunctional (meth)acrylate and / or an allyl (meth)acrylate; 0-15% by weight, preferably 0-12% by weight, more preferably 0.5-10% by weight, optionally further monomers, preferably different from the above mentioned monomers, such as vinyl aromatic monomers, e.g. styrene, benzyl methacrylate, The composition comprises (preferably consists of)

[0065] The amounts are given relative to the total mass of the monomers.

[0066] Multi-phase alkyl (meth)acrylate emulsion polymers may contain vinyl aromatic monomers, such as styrene and / or C7-C acrylates, to adjust the refractive index difference between the hard and soft phases. 20 It is preferred to include aralkyl (meth)acrylates, such as benzyl methacrylate. Styrenes that may be used are styrene, substituted styrenes having alkyl substituents on the side chain, such as α-methylstyrene and α-ethylstyrene, substituted styrenes having alkyl substituents on the ring, such as vinyltoluene and p-methylstyrene, and halogenated styrenes, such as monochlorostyrene, dichlorostyrene, tribromostyrene, and tetrabromostyrene.

[0067] Typically, the crosslinking monomer has two or more polymerizable double bonds in the molecule. The crosslinking monomer may be selected from difunctional (meth)acrylates, trifunctional or multifunctional (meth)acrylates, and other known crosslinkers such as allyl methacrylate, allyl acrylate, and divinylbenzene.

[0068] For example, difunctional (meth)acrylates are diesters of (meth)acrylic acid with polyfunctional alcohols, such as di(meth)acrylates of propanediol, butanediol, hexanediol, octanediol, nonanediol, decanediol, eicosanediol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, dodecaethylene glycol, tetradecaethylene glycol, propylene glycol, dipropyl glycol, and tetradecapropylene glycol. For example, trifunctional or polyfunctional (meth)acrylates are tri- or multi-esters of (meth)acrylic acid with polyfunctional alcohols, such as trimethylolpropane tri(meth)acrylate and pentaerythritol tetra(meth)acrylate.

[0069] Suitable cross-linking monomers are described, for example, in WO 02 / 20634 and EP 0522351.

[0070] Preferably, the alkyl (meth)acrylate emulsion polymer comprises at least one crosslinking monomer selected from ethylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, divinylbenzene, and allyl (meth)acrylate. More preferably, the crosslinking monomer is allyl methacrylate.

[0071] The alkyl (meth)acrylate emulsion polymer may contain 0 to 15% by weight, preferably 0 to 10% by weight, more preferably 0.5 to 5% by weight, of further components, such as auxiliaries or residues of auxiliaries added during polymerization and / or further processing, such as emulsifiers, initiators, buffers or molecular weight regulators, as described below, based on the solids content of the emulsion polymer. In particular, the alkyl (meth)acrylate emulsion polymer may contain 0 to 15% by weight, preferably 0.001 to 10% by weight, more preferably 0.01 to 5% by weight, of molecular weight regulators, as described below, based on the solids content of the emulsion polymer.

[0072] Core-shell emulsion polymer For example, the impact modifiers are based on two-phase emulsion polymers consisting of a soft elastomeric core and a hard shell, as described for example in EP 0 528 196, DE 3 842 796 and DE 10 2005 062 687. In particular, said core-shell emulsion polymers can be obtained by a two-step emulsion polymerization in water, as described for example in DE 3 842 796 (A). In a first step, the core particles are prepared by emulsion polymerization and the shell is prepared by emulsion polymerization of a monomer mixture in the presence of the core particles.

[0073] Typically, the hard phase has a glass transition temperature T above 70° C. g and contains 80-100% by weight of methyl methacrylate relative to the hard phase. Typically, the soft core has a glass transition temperature T g With respect to the soft core, 50 to 99.5% by weight of C1 to C 10 The soft core comprises an alkyl acrylate and 0.5 to 5% by weight of a crosslinking monomer. Further, the soft core has a glass transition temperature T g and may contain 50 to 100% by weight of at least one conjugated diene, such as butadiene, based on the soft core.

[0074] In a preferred embodiment, the multi-phase alkyl (meth)acrylate emulsion polymer comprises: A1) 10 to 95% by weight of the total emulsion polymer has a glass transition temperature T g having A1.1) At least one of C1 to C, which is 50 to 99.5% by weight based on A1 10 an alkyl acrylate, preferably n-butyl acrylate; A1.2) 0.5 to 5% by weight, based on A1, of at least one crosslinking monomer having two or more ethylenically unsaturated groups, and A1.3) 0 to 10% by weight, based on A1, of at least one further ethylenically unsaturated free-radically polymerizable monomer. A soft elastomeric core A1, B1) 5 to 90% by weight of the total emulsion polymer, the glass transition temperature T g having B1.1) 80-100% by weight, based on B1, of at least one C1-C6 alkyl methacrylate, preferably methyl methacrylate, and B1.2) 0-20% by weight, based on B1, of at least one further ethylenically unsaturated free-radically polymerizable monomer, for example an ethylenically unsaturated free-radically polymerizable monomer selected from C1-C6 alkyl acrylates, such as butyl acrylate or ethyl acrylate. and a rigid shell B1 constructed from The core-shell emulsion polymer is a polymer comprising (preferably consisting of)

[0075] In another preferred embodiment, the multi-phasic alkyl (meth)acrylate emulsion polymer comprises A1) 50 to 90% by weight of the emulsion polymer has a glass transition temperature Tg of less than -10 ° C., A1.1) 90 to 100% by weight of at least one conjugated diene, preferably butadiene, based on A1; A1.2) 0 to 5% by weight, based on A1, of at least one crosslinking monomer having two or more ethylenically unsaturated groups, and A1.3) 0 to 10% by weight, based on A1, of at least one further ethylenically unsaturated free-radically polymerizable monomer, such as at least one vinyl aromatic monomer, preferably styrene and / or α-methylstyrene. A soft elastomeric core A1, B1) 10 to 50% by weight of the total emulsion polymer has a glass transition temperature Tg of more than 70 ° C.; B1.1) 70 to 90% by weight, based on B1, of at least one C1 to C6 alkyl methacrylate, preferably methyl methacrylate, and B1.2) 10 to 30% by weight, based on B1, of at least one further ethylenically unsaturated free-radically polymerizable monomer, for example an ethylenically unsaturated free-radically polymerizable monomer selected from vinyl aromatic monomers, preferably styrene and / or α-methylstyrene. and a rigid shell B1 constructed from The core-shell emulsion polymer is a polymer comprising (preferably consisting of)

[0076] Preferably, the degree of grafting of the core-shell emulsion polymer is at least 50% by weight, preferably 50-60% by weight, based on the total solids content of the emulsion polymer.

[0077] In general, the glass transition temperature T of a polymer or a phase of a multiphase emulsion polymer g The glass transition temperature T can be determined in a known manner by differential scanning calorimetry (DSC). g can also be calculated as an approximation using the Fox formula.

[0078] Core-Shell-Shell Emulsion Polymer For example, the impact modifier may have a hard core constructed from, for example, crosslinked methyl methacrylate and a crosslinked C1-C 10 It is based on a three-phase emulsion polymer composed of a soft intermediate shell constructed from an alkyl acrylate, preferably n-butyl acrylate, and a hard outer shell constructed, for example, from non-crosslinked methyl methacrylate. Typically, said core-shell-shell emulsion polymers are prepared as described in EP 1 332 166 B1, WO 02 / 20634 and EP 0 522 351.

[0079] In particular, the poly(alkyl)methacrylate impact modifier may include a methacrylate / butadiene / styrene copolymer or an acrylate / methacrylate copolymer.

[0080] In a preferred embodiment, the multi-phase alkyl (meth)acrylate emulsion polymer comprises: A2) 5 to 40% by weight of the total emulsion polymer, a glass transition temperature T g having A2.1) 80-100% by weight, based on A2, of at least one C1-C6 alkyl methacrylate, preferably methyl methacrylate; A2.2) 0 to 20% by weight, based on A2, of at least one further ethylenically unsaturated free-radically polymerizable monomer, and A2.3) 0-5% by weight, based on A1, of at least one crosslinking monomer having two or more ethylenically unsaturated groups. a hard non-elastomeric core A2 constructed from B2) 20 to 75% by weight of the total emulsion polymer, having a glass transition temperature T g having B2.1) 45 to 99.5% by weight of at least one of C1 to C 10 an alkyl acrylate, preferably n-butyl acrylate; B2.2) 0.5 to 5% by weight, based on B2, of at least one crosslinking monomer having two or more ethylenically unsaturated groups, and B2.3) 0 to 50% by weight, based on B2, of at least one further ethylenically unsaturated free-radically polymerizable monomer, preferably a monomer having an aromatic group. a soft elastomeric intermediate shell B2 constructed from C2) 15 to 60% by weight of the total emulsion polymer, the glass transition temperature T g having C2.1) 80 to 100% by weight, preferably 90 to 100% by weight, based on C2, of at least one C1 to C6 alkyl methacrylate, preferably methyl methacrylate, and C2.2) 0 to 20% by weight, preferably 0 to 10% by weight, based on C2, of at least one further ethylenically unsaturated free-radically polymerizable monomer with a rigid outer shell C2 constructed from The core-shell-shell emulsion polymer is a core-shell-shell emulsion polymer comprising (preferably consisting of)

[0081] Preferably, at least 15% by weight, more preferably at least 25% by weight, of the hard outer shell C2 is covalently bonded to the soft elastomeric intermediate shell B2.

[0082] Preferably, the degree of grafting of the core-shell-shell emulsion polymer is at least 50% by weight, preferably 70-99% by weight, based on the total solids content of the emulsion polymer.

[0083] Method for producing poly(meth)acrylate impact modifiers Furthermore, the present invention relates to a method for producing a (i) preparation of at least one multiphasic alkyl (meth)acrylate emulsion polymer by emulsion polymerization, in particular by sequential emulsion polymerization, in which the multiphasic alkyl (meth)acrylate emulsion polymer is obtained in the form of a latex, (ii) coagulation and dehydration, preferably mechanical dehydration, of the latex obtained in step (i), wherein the coagulation is carried out by physical coagulation to obtain a dehydrated alkyl (meth)acrylate emulsion polymer, the dehydrated alkyl (meth)acrylate emulsion polymer containing 3.0 mmol / kg or less, preferably 2.5 mmol / kg or less of alkali metal ions based on the solid content of the alkyl (meth)acrylate emulsion polymer, and the molar ratio of alkali ions to polyvalent metal ions in the dehydrated alkyl (meth)acrylate emulsion polymer is 1.3 or less, preferably 1.2 or less. Inclusive of A coagulant comprising at least one salt of a polyvalent metal ion, preferably at least one salt of a polyvalent metal ion selected from alkaline earth metals, zinc and aluminum, is added to the emulsion polymer before and / or during coagulation; Concerned is a method for making the poly(meth)acrylate impact modifier of the present invention, which comprises at least one multi-phase alkyl(meth)acrylate emulsion polymer.

[0084] The preferred embodiments mentioned above in relation to the impact modifier of the present invention apply accordingly to the process of the present invention.

[0085] In particular, the poly(meth)acrylate impact modifier comprising, or preferably consisting essentially of, a multi-phase alkyl (meth)acrylate emulsion polymer can be obtained as a dry polymer powder, especially after dehydration and drying.

[0086] In particular, the poly(meth)acrylate impact modifier, which comprises or preferably consists essentially of a multi-phase alkyl (meth)acrylate emulsion polymer, can be obtained in the form of polymer granules.For example, the polymer powder obtained after drying can be granulated, for example by a commonly known melt extrusion process, optionally with the addition of one or more additives and / or one or more additional polymer components.Furthermore, the impact modifier can be obtained in the form of polymer granules, and the solidification and dehydration in step ii) can be carried out by thermal shear solidification in an extruder.

[0087] In a preferred embodiment, coagulation is performed by freeze coagulation and the aqueous phase of the coagulated emulsion polymer is at least partially removed by mechanical dewatering, for example in a centrifugation step. Typically, the water content of the dewatered emulsion polymer is in the range of 5-40% by weight, preferably 7-30% by weight, based on the dewatered emulsion polymer. In a preferred embodiment, the coagulation and dewatering in step (ii) is performed as described in WO 2015 / 074883.

[0088] Preferably, step (ii) may include a sintering step as described below. Additionally, the method of the present invention may include one or more washing steps (iii) and / or one or more drying steps (iv) as described below.

[0089] In a preferred embodiment, the coagulation and dewatering in step ii) is carried out by extrusion. Typically, the latex obtained by emulsion polymerization is introduced into an extruder, which typically comprises a coagulation zone, a dewatering zone and a devolatilization zone. Preferably, the coagulation and dewatering by extrusion can be carried out as described in WO 02 / 18453, EP 0683028 or EP 0187715.

[0090] In another preferred embodiment, the coagulation and dehydration in step ii) is carried out by freeze coagulation. Preferably, the coagulation and dehydration by freeze coagulation can be carried out as described in WO 2015 / 074883.

[0091] Emulsion polymerization (step (i)) The process of the present invention includes an emulsion polymerization step (i) in which at least one multiphasic alkyl(meth)acrylate polymer is prepared by emulsion polymerization, in particular by sequential emulsion polymerization, to obtain the multiphasic alkyl(meth)acrylate emulsion polymer in the form of a latex.

[0092] The multiphase emulsion polymers are prepared in the aqueous phase in the usual manner by two-stage, three-stage or multi-stage emulsion polymerization. Typically, the emulsion polymerization stages are carried out at temperatures in the range of 20 to 100°C, preferably 60 to 90°C.

[0093] Generally, the core is prepared by emulsion polymerization in a first stage. Typically, the core has an average particle size of 50-150 nanometers (nm) for core-shell emulsion polymers and 100-300 nanometers (nm) for core-shell-shell emulsion polymers. Methods for adjusting the desired particle size are known to those skilled in the art. Advantageously, the particle size control is performed according to the seed latex method, for example, as described in US 2007 / 0123610 A1 and WO 2004 / 056893.

[0094] In the case of core-shell emulsion polymers, the hard outer phase is prepared in a second polymerization stage, after completion of the first polymerization stage, in the presence of the soft core.

[0095] In the case of core-shell-shell emulsion polymers, the elastomeric mesophase is prepared in a second polymerization stage in the presence of the core after the first polymerization stage has been completed. Finally, in a third stage, after the second polymerization stage has been completed, the final rigid phase is also made in the presence of the emulsion polymer of the second stage.

[0096] Emulsion polymerization is preferably carried out in the presence of anionic emulsifier.Generally known anionic emulsifiers are, for example, alkyl sulfates, alkyl sulfonates, alkyl sulfonic acids, aralkyl sulfonates, soaps of saturated or unsaturated fatty acids.Preferably, anionic emulsifiers are used that are selected from sulfonates, alkyl sulfosuccinates, and alkoxylated and sulfated paraffins, and mixtures thereof.

[0097] Preferably, the emulsion polymer latex is polymerized by aqueous free radical emulsion polymerization. The reaction is typically initiated via a water- or oil-soluble free radical polymerization initiator.

[0098] For example, suitable polymerization initiators are selected from inorganic or organic peroxides such as dilauroyl peroxide, tert-butyl peroctoate, tert-butyl perisononanoate, dicyclohexyl peroxydicarbonate, dibenzoyl peroxide and 2,2-bis(tert-butylperoxy)butane; azo compounds such as 2,2'-azobis(isobutyronitrile) and 2,2'-azobis(2,4-dimethylvaleronitrile), and redox initiator systems.Examples of suitable redox systems are the combination of tertiary amines and peroxides, or the combination of sodium disulfite and potassium, sodium or ammonium persulfates, or preferably peroxides.

[0099] In order to keep the flow of free radicals constant during the course of the polymerization or at different polymerization temperatures, it is also preferred to carry out the polymerization using a mixture of different polymerization initiators with different half-life times, for example dilauroyl peroxide and 2,2-bis(tert-butylperoxy)butane.

[0100] The polymerization initiator is typically used in an amount of 0.01 to 2% by weight based on the monomer mixture. Typically, the polymerization initiator is used in the range of 0.01 to 0.5% by weight based on the aqueous emulsion polymerization mixture.

[0101] Preferably, an alkali metal peroxydisulfate or ammonium peroxydisulfate is used as a polymerization initiator, for example 0.01 to 0.5% by weight based on the aqueous phase of the polymerization mixture, and the polymerization is preferably initiated at a temperature of 20°C to 100°C.

[0102] Preferably, a redox system is used as polymerization initiator, for example 0.01-0.05 wt. % of an organic hydroperoxide and 0.05 wt. %-0.15 wt. % of sodium hydroxymethylsulfinate (e.g. Rongalite®), each relative to the aqueous phase of the polymerization mixture, and the polymerization is preferably initiated at a temperature in the range of 20° C. to 80° C.

[0103] The chain length of the polymer, especially in the outer hard phase, can be adjusted by polymerizing the monomer mixture in the presence of a molecular weight regulator. In particular, known mercaptans such as n-butyl mercaptan, n-dodecyl mercaptan, 2-mercaptoethanol, or 2-ethylhexyl thioglycolate, or pentaerythritol tetrathioglycolate, can be used for this purpose. Typically, the amount of molecular weight regulator is 0.05-5% by weight relative to the monomer mixture, preferably 0.1-2% by weight relative to the monomer mixture, particularly preferably 0.2-1% by weight. Preferably, n-dodecyl mercaptan is used as the molecular weight regulator.

[0104] Furthermore, it is possible to use salts, acids and bases in the emulsion polymerization, in particular to adjust the pH or to buffer the reaction mixture. For example, solutions of sodium and potassium salts of sulfuric acid, phosphoric acid, sodium hydroxide, potassium hydroxide, carbonate, bicarbonate, sulfate and / or phosphoric acid (e.g. tetrasodium pyrophosphate) can be used. Typically, the emulsion polymer latex obtained in step (i) has a pH value in the range of 2 to 7, preferably 2.5 to 6.

[0105] Typically, the emulsion polymer latex obtained in step (i) has a solid content in the range of 20 to 60% by weight based on the total weight of the emulsion polymer latex. The solid content can be adjusted as necessary.

[0106] Coagulation and mechanical dewatering (step (ii)) The method of the present invention includes coagulation and dehydration in step (ii), preferably mechanical dehydration, and the latex obtained in step (i) is coagulated by physical coagulation, preferably physical coagulation selected from shear coagulation, thermal shear coagulation, spray drying, freeze coagulation and pressure coagulation, more preferably by freeze coagulation, shear coagulation or thermal shear coagulation, to obtain a dehydrated alkyl (meth)acrylate emulsion polymer containing 3.0 mmol / kg or less, preferably 2.5 mmol / kg or less of alkali metal ion based on the solid content of the alkyl (meth)acrylate emulsion polymer, and the molar ratio of alkali ion to polyvalent metal ion in the dehydrated alkyl (meth)acrylate emulsion polymer is 1.3 or less, preferably 1.2 or less.

[0107] According to the present invention, "coagulation by physical means" or "physical coagulation" refers to the aggregation and precipitation of polymer particles in an emulsion polymer latex by applying a physical process, typically reducing the repulsive forces between the polymer particles resulting in the separation and stabilization of the polymer particles in the latex. Typically, "chemical coagulation" refers to the aggregation and precipitation of polymer particles in an emulsion polymer latex, typically by the addition of a chemical agent (coagulant) that neutralizes some or all of the stabilizing charges located on the polymer particles.

[0108] According to the process for producing the poly(meth)acrylate impact modifier of the present invention, coagulation is carried out by physical coagulation in combination with the addition of a coagulant prior to and / or during coagulation (i.e., by a combination of physical and chemical coagulation).

[0109] Physical coagulation of the emulsified polymer latex can be carried out by spray drying, by freeze coagulation (as described, for example, in WO 2015 / 07488), or by mechanical and / or thermal stress, especially using a degassing extruder (as described, for example, in WO 2002 / 18453, EP 0 979 162(A), EP 0 683 028(A)).

[0110] According to the present invention, a coagulant comprising at least one salt of a polyvalent metal ion, preferably selected from alkaline earth metals, zinc and aluminum, more preferably selected from magnesium, calcium and aluminum, is added to the emulsified polymer before and / or during coagulation. In a preferred embodiment, at least one calcium salt is added as the coagulant. Preferably, the coagulant is an aqueous solution of at least one salt of a polyvalent metal ion, preferably selected from alkaline earth metals, zinc and aluminum, more preferably selected from magnesium, calcium and aluminum. Typically, said aqueous solution comprises 2-30% by weight, preferably 5-25% by weight, of said at least one salt of a polyvalent metal ion. Preferably, the aqueous solution of the salt of the at least one polyvalent metal ion is a true transparent solution, in which the total amount of the polyvalent metal ion is in solvated form.

[0111] Typically, the coagulant is an aqueous solution of at least one salt of a polyvalent metal ion having good solubility in water. Preferably, the salt of the polyvalent metal ion should have a solubility in water (for example at a temperature of 20-25°C, preferably at room temperature, 23°C) of 0.1 mol / l or more, preferably 0.5 mol / l or more, more preferably 1.0 mol / l or more, also preferably 3.0 mol / l or more. In particular, the salt of the polyvalent metal ion is selected from water-soluble acetates, chlorides, hydroxides and / or sulfates, water-soluble referring to a solubility in water of at least 0.1 mol / l, preferably at least 1.0 mol / l, at room temperature, 23°C. For example, an aqueous solution of calcium acetate, calcium chloride, calcium hydroxide, magnesium sulfate, magnesium chloride, aluminum sulfate or mixtures thereof can be used as the coagulant.

[0112] In particular, the coagulating agent is selected to avoid the formation of poorly water-soluble metal salts or water-insoluble salts in the coagulation mixture.

[0113] Typically, the pH value of the coagulation mixture during the coagulation step is in the range of 2-7, preferably 2.5-6.

[0114] Typically, at least one salt of polyvalent metal ions, preferably at least one salt of polyvalent metal ions selected from alkaline earth metals, zinc and aluminum, is added in an amount of 0.01 to 10% by weight, preferably 0.02 to 5% by weight, more preferably 0.03 to 3% by weight, based on the solid content of the polymer dispersion. In particular, at least one salt of polyvalent metal ions is added in an amount of 0.01 to 2 molar concentration based on the total molar amount of alkali metal ions in the emulsion polymer latex obtained in step (i). For example, 0.01 to 2 mol of alkaline earth metal ions are added to the emulsion polymer latex for 1 mol of alkali metal ions.

[0115] In particular, the salt of at least one polyvalent metal ion is selected from metal halides, such as chlorides, metal sulfates, metal phosphates, such as orthophosphates or pyrophosphates, metal hydroxides, organic acid metal salts, such as metal acetates, metal oxalates, metal citrates and metal formats. Preferably, the salt of at least one polyvalent metal ion is selected from chlorides, sulfates and acetates. Furthermore, typically known hydrates of said salts can be utilized.

[0116] For example, suitable alkaline earth metal salts here are magnesium sulfate (e.g. kieserite (Mg[SO4]·H2O), pentahydrite (Mg[SO4]·5H2O), hexahydrite (Mg[SO4]·6H2O) and epsomite (Mg[SO4]·7H2O, Epsom salts)), magnesium chloride, calcium chloride, calcium hydroxide, calcium acetate, calcium formate, magnesium formate or mixtures thereof. The use of calcium acetate is particularly preferred.

[0117] For example, suitable aluminum salts are aluminum sulfate (Al2(SO4)3), aluminum sulfate hydrate, aluminum chloride (AlCl3), aluminum chloride hydrate, aluminum chlorhydrate, and polyaluminum chloride.

[0118] For example, suitable zinc salts are zinc chloride (ZnCl2), zinc sulfate (ZnSO4), zinc sulfate hydrate (eg, ZnSO4·7H2O), and zinc oxalate.

[0119] It is also possible to use mixtures of two or more of the abovementioned salts of polyvalent metal ions, for example a combination of at least an alkaline earth metal salt and at least one aluminum salt.

[0120] Typically, the solidification can be carried out within a temperature range of 20 to 100°C, preferably 30 to 80°C.

[0121] Dewatering of the coagulated latex can be accomplished by mechanical dewatering (e.g., centrifugation and / or filtration) and / or by thermal dewatering (e.g., by evaporation of the aqueous phase of the emulsified polymer, such as by spray drying). Additionally, coagulation and dewatering of the emulsified polymer latex can occur in one step, such as in the case of spray drying or coagulation and dewatering in a degassing extruder.

[0122] Preferably, dewatering of the coagulated emulsion polymer is accomplished by mechanical dewatering, such as by centrifugation, decantation or filtration. Preferably, the coagulated emulsion polymer is dewatered by batch or continuous centrifugation. The coagulated emulsion polymer is typically centrifuged for 90 seconds to 10 minutes.

[0123] According to another embodiment of the invention, the dewatering of the coagulated emulsion polymer is carried out by means of a degassing extruder, in particular in at least one dewatering zone of the extruder used for the shear or hot shear coagulation of the emulsion polymer.

[0124] Typically, the dehydrated emulsion polymer obtained in step (ii) has a water content of 40% by weight or less, preferably in the range of 2 to 35% by weight, more preferably 5 to 20% by weight.

[0125] The water content of the multi-stage emulsion polymer after dehydration (also called residual water content) is the water content in weight percent relative to the wet polymer obtained after dehydration. The water content is determined in particular using a suitable analytical device (e.g. drying and weighing device) and the sample is dried until a constant weight of the sample is achieved over a defined period of time. As an example, the water content of the emulsion polymer can be determined with a moisture analyzer and the sample is dried at a temperature in the range of 80-180°C. In particular, the water content can be determined using a Halogen Moisture Analyzer from Mettler Toledo at 160°C until a constant weight is achieved for 30 seconds.

[0126] Preferably, the dehydrated alkyl (meth)acrylate emulsion polymer obtained in the dehydration step (ii) or after the optional washing step (iii) comprises 0 to 3.0 mmol / kg, preferably 0 to 2.5 mmol / kg, also preferably 0.0 to 2.0 mmol / kg, particularly preferably 0.01 to 3 mmol / kg of alkali metal ions (e.g. sodium and / or potassium) based on the solids content of the emulsion polymer, and 0.5 to 20.0 mmol / kg, preferably 2.0 to 10.0 mmol / kg, more preferably 2.0 to 8.0 mmol / kg of polyvalent metal ions, preferably selected from alkaline earth metals (e.g. magnesium and / or calcium), zinc and aluminum, based on the solids content of the emulsion polymer.

[0127] Optional sintering In particular, step (ii) of the process of the present invention involves a sintering step after coagulation of the emulsion polymer and prior to dewatering.

[0128] Preferably, step (ii) may include a sintering step, and the solidified multi-stage alkyl (meth)acrylate emulsion polymer has a glass transition temperature, T g Near or below the sintering temperature (T s Preferably, the optional sintering step is carried out after solidification and before dehydration. In particular, the optional sintering step is carried out at a temperature of T s ≧T g -50K, preferably T s ≧T g -30K, more preferably T g -15K≦T s ≦T g It is carried out at a temperature of +5K.

[0129] Preferably, the coagulation mixture, after coagulation of the emulsion polymer, is kept at a temperature (sintering temperature) in the range of 60° C. to 140° C., preferably 70° C. to 135° C., more preferably 75° C. to 130° C. In particular, the coagulated emulsion polymer is kept at said sintering temperature T2 for a period of 2 minutes to 24 hours, preferably 2 to 15 minutes, preferably 3 to 10 minutes, more preferably 5 to 10 minutes.

[0130] In a preferred embodiment, the coagulated emulsion polymer may be treated with steam after coagulation during the sintering process.

[0131] The process for making the poly(meth)acrylate impact modifier may include one or both of the following optional steps: (iii) optionally washing the dehydrated alkyl (meth)acrylate emulsion polymer; (iv) Optionally, drying the dehydrated alkyl (meth)acrylate emulsion polymer obtained in step ii) or iii).

[0132] Optional washing step (iii) In a preferred embodiment, mechanical dehydration of the emulsion polymer in step (ii) is followed by a washing step (iii), in which the dehydrated emulsion polymer is preferably treated with water or a mixture of water and a polar water-miscible organic solvent. The water or mixture is preferably removed after treatment by filtration or centrifugation. Preferably, in the downstream washing step (iii), an emulsion polymer is obtained having a water content of 40% by weight or less, preferably in the range of 2-35% by weight, more preferably 5-20% by weight.

[0133] For example, the washing step (iii) can be carried out by adding water, or a mixture of water and a polar water-miscible organic solvent, during the centrifugation, especially during a continuous centrifugation process.

[0134] Preferably, the dehydrated emulsion polymer obtained after optional washing step (iii) exhibits amounts of alkali metal ions and polyvalent metal ions, such as alkaline earth metal ions, zinc ions or aluminium ions, as described above for the dehydrated emulsion polymer obtained after step (ii).

[0135] Optional drying step (iv) The process for preparing the poly(meth)acrylate impact modifiers of the present invention may include one or more optional drying steps (iv).

[0136] For example, the dehydrated emulsion polymer can be dried by a hot drying gas, such as air, or by an air dryer. Drying can be carried out, for example, in a cabinet dryer or other commonly known drying equipment, such as a flash dryer or a fluidized bed dryer. Typically, the optional drying step (iv) is carried out at a temperature in the range of 50 to 160°C, preferably 55 to 155°C, particularly preferably 60 to 150°C.

[0137] In another embodiment, the coagulated and dewatered emulsion polymer is dried in a degassing extruder, particularly in an additional degassing section of the extruder used for coagulation and dewatering.

[0138] Typically the resulting dry emulsion polymer has a water content of less than 5%, preferably less than 2%, preferably in the range of 0.05 to 2% by weight, preferably 0.1 to 1.5% by weight, particularly preferably 0.1 to 1% by weight.

[0139] Preferably, the dried emulsion polymer, e.g. obtained as a powder or granules, exhibits the same amount of alkali metal ions and polyvalent metal ions, e.g. alkaline earth metal ions, zinc ions and aluminium ions, as the dehydrated and optionally washed emulsion polymer obtained after step (ii) or (iii).

[0140] In a preferred embodiment of the present invention, in step (ii), the coagulation is carried out by freeze coagulation, and the mechanical dewatering of the coagulated emulsion polymer is carried out by centrifugation, and the water content of the dehydrated emulsion polymer is not more than 40% by weight based on the dehydrated emulsion polymer, and the process comprises: (iii) optionally washing the dehydrated alkyl (meth)acrylate emulsion polymer; (iv) drying the dehydrated alkyl(meth)acrylate emulsion polymer obtained in step ii) or iii), whereby the poly(meth)acrylate impact modifier is obtained as a polymer powder.

[0141] In another preferred embodiment of the present invention, in step (ii), the coagulation and mechanical dewatering are carried out by thermal shear coagulation, the latex obtained in step (i) is introduced into an extrusion line comprising at least one coagulation zone, at least one dewatering zone and at least one degassing zone, and the poly(meth)acrylate impact modifier is obtained as polymer granules.

[0142] Optional ion exchange step The process for preparing the impact modifier of the present invention may preferably comprise at least one ion exchange step in which the latex obtained in step (i) is contacted with an ion exchange material. Preferably, the latex does not show coagulation in the optional ion exchange step, and the latex obtained in the optional ion exchange step is processed as described above in a subsequent coagulation step (ii).

[0143] In general, the ion exchange material can be at least one cation exchange material (i.e., a material containing an anionic group capable of being loaded with a proton H+) and / or at least one anion exchange material (i.e., a material containing a cationic basic group). Different ion exchange materials can be used as a mixture in one contact step with the emulsion polymer latex and / or consecutively in two or more contact steps with the emulsion polymer latex. For example, it is possible to contact the latex obtained in step (i) with an anion exchange material in a first step, and then contact the latex with a cation exchange material in a second step. Furthermore, it is possible to use mixed ion exchange materials containing anion exchange groups and cation exchange groups.

[0144] Preferably, at least one cation exchange material is used to reduce the amount of alkali metal ions before coagulation in step (ii). In a preferred embodiment, the latex obtained in step (i) is contacted in step (ii) with at least one cation exchange material, more preferably a strong acid cation exchange material, especially in the protonated form (H form). Suitable cation exchange materials contain at least one acid group, such as a carboxylic acid group (-COOH) or a sulfonic acid group (-S(=O)2OH), preferably a strong acid group, such as a sulfonic acid group. If the cation exchange material is not in the protonated form, e.g. the Na form, it can be treated with an aqueous acid, such as hydrochloric acid or sulfuric acid, to obtain the protonated H form of the exchange material.Suitable examples of commercially available cation exchange materials are available from Dow Chemical under the trade names / trademarks DOWEX® MARATHON C, DOWEX® MONOSPHERE C-350, DOWEX® HCR-S / S, DOWEX® MARATHON MSC, DOWEX® MONOSPHERE 650C, DOWEX® HCR-W2, DOWEX® MSC-1, DOWEX® HGR NG(H), DOWEX® DR-G8, DOWEX® 88, DOWEX® MONOSPHERE 88, DOWEX® MONOSPHERE C-600 B, DOWEX® MONOSPHERE M-31, DOWEX® MONOSPHERE DR-2030, DOWEX® M-31, DOWEX® G-26(H), DOWEX® 50 W-X4, DOWEX® 50W-X8, DOWEX® 66. ion exchange resins manufactured by Rohm and Haas under the trade names / trade names Amberlyst® 131, Amberlyst® 15, Amberlyst® 16, Amberlyst® 31, Amberlyst® 33, Amberlyst® 35, Amberlyst® 36, Amberlyst® 39, Amberlyst® 40, Amberlyst® 70, Amberlite® FPC11, Amberlite® FPC22, Amberlite® FPC23; ion exchange resins manufactured by Brotech Corp. under the trade names / trade names Purofine® PFC150, Purolite® C145, Purolite® C150, Purolite® C160, Purolite® PFC100, Purolite® C100; and Monoplus® S100 and Tulsion® T42 is an ion exchange resin manufactured by Thermax Limited Corp. Other acidic cation exchange resins known to those skilled in the art may also be used.Preferably, Dowex® Marathon C manufactured by Dow Chemical is used.

[0145] The latex obtained in step (i) can be contacted with at least one ion exchange material in any suitable manner, for example, the ion exchange step can be carried out by dispersing the ion exchange material in the latex or in a column ion exchange step.

[0146] Furthermore, the method of the present invention comprises: (v) adding one or more additives to the multi-phase alkyl (meth)acrylate emulsion polymer; The method may include the optional steps of:

[0147] At each stage of the process for making the poly(meth)acrylate impact modifiers of the present invention, for example, before or during dehydration of the coagulated emulsion polymer, suitable conventional additives can be mixed in. Among these are dyes, pigments, stabilizers, lubricants, UV protection agents, and the like.

[0148] The optional additive may be selected from the commonly known additives and / or auxiliaries for plastic materials.For conventional auxiliaries and additives, refer to "Plastics Additives Handbook", Hans Zweifel, 6th edition, Hanser Publ., Munich, 2009, for example.For example, the at least one additive may be selected from fillers, reinforcing agents, dyes, pigments, lubricants or release agents, stabilizers, especially light and heat stabilizers, antioxidants, UV absorbers, plasticizers, impact modifiers, antistatic agents, flame retardants, bactericides, fungicides, optical brighteners, and foaming agents.

[0149] For example, the impact modifier may contain 0 to 15% by weight, preferably 0 to 10% by weight, more preferably 0.5 to 5% by weight of at least one of the additives described above, based on the solid content of the impact modifier.

[0150] Thermoplastic molding composition and method for its manufacture In another aspect, the present invention is directed to a thermoplastic molding composition (hereinafter also called molding composition) comprising the poly(meth)acrylate impact modifier of the present invention and optionally at least one resin based on a thermoplastic (meth)acrylate polymer. For example, such impact-modified poly(meth)acrylate molding compositions are described in WO 2004 / 056893.

[0151] In particular, the thermoplastic molding composition 1 to 100% by weight, preferably 5 to 100% by weight, of at least one poly(meth)acrylate impact modifier as defined above, based on the total molding composition; 0 to 99% by weight, preferably 0 to 95% by weight, of at least one thermoplastic (meth)acrylate polymer, preferably poly(methyl methacrylate), relative to the total molding composition; 0 to 50% by weight, preferably 0 to 10% by weight, based on the total molding composition, of one or more additives, preferably two or more additives, selected for example from UV absorbers, UV stabilizers, heat stabilizers, antioxidants, lubricants, dyes and processing agents, and / or one or more additional polymer components; The composition comprises (preferably consists of)

[0152] Typically, the thermoplastic (meth)acrylate polymers here preferably comprise, in each case relative to their total weight, 50.0 to 100.0% by weight, preferably 60.0 to 100.0% by weight, particularly preferably 75.0 to 100.0% by weight, particularly preferably 85.0 to 99.5% by weight of an alkyl methacrylate monomer (each a repeating unit) having 1 to 20, preferably 1 to 12, more preferably 1 to 8, particularly preferably 1 to 4 carbon atoms in the alkyl group; 0.0 to 40.0% by weight, preferably 0.0 to 25.0% by weight, in particular 0.1 to 15.0% by weight of alkyl acrylate monomers having 1 to 20, preferably 1 to 12, advantageously 1 to 8, in particular 1 to 4 carbon atoms in the alkyl group (respective repeat units), 0.0 to 30% by weight, preferably 0.0 to 8.0% by weight of a styrene monomer (each a repeating unit), The composition comprises (preferably consists of)

[0153] In particular, the thermoplastic (meth)acrylate polymer comprises, relative to its total weight, at least 50.0% by weight, advantageously at least 60.0% by weight, preferably at least 75.0% by weight and in particular at least 85.0% by weight of methyl methacrylate.

[0154] For example, the molding composition may include one or more additives and / or one or more additional polymeric components selected from dyes, pigments, and crosslinked polymer beads.

[0155] In a preferred embodiment, the above-mentioned inventive thermoplastic molding composition comprises up to 50% by weight, preferably from 0.0001% by weight to 50% by weight, based on the total thermoplastic molding composition, of at least one dye and / or pigment, for example selected from perinone dyes, quinophthalone dyes, anthraquinone dyes, azo dyes, inorganic pigments, phthalocyanine pigments and carbon black.

[0156] Furthermore, the above-mentioned inventive thermoplastic molding composition may contain from 0.01% by weight to 50% by weight, based on the total thermoplastic molding composition, of at least one crosslinked polymer bead, preferably chosen from crosslinked polymer beads (scattering beads) having a refractive index different from that of the polymer matrix formed by the thermoplastic molding composition. Suitable crosslinked polymer beads are described below.

[0157] Typically, the thermoplastic (meth)acrylate polymers have a number-average molar mass in the range of 1000 to 100,000,000 g / mol, preferably in the range of 10,000 to 1,000,000 g / mol, in particular in the range of 50,000 to 500,000 g / mol, which can be determined, for example, by gel permeation chromatography using a calibration based on polymethyl methacrylate.

[0158] Furthermore, the present invention is directed to a process for the preparation of a thermoplastic molding composition, in which the components, typically in the form of a melt or in the form of powder or pellets, are mixed and homogenized, for example in a single-screw or multiple-screw extruder or a roll mill.

[0159] In particular, the process for the preparation of a thermoplastic molding composition comprises xi) mixing 5-100% by weight, based on the total molding composition, of at least one poly(meth)acrylate impact modifier according to the invention as described above, 0-95% by weight, based on the total molding composition, of at least one thermoplastic (meth)acrylate polymer, and optionally 0-10% by weight of another additive and / or one or more additional polymeric components, xii) melt-kneading the mixture obtained in step xi) at a temperature preferably in the range of 200-280° C.; Includes.

[0160] Conventional additives may be mixed in at any processing stage suitable for this purpose, including dyes, pigments, fillers, reinforcing fibers, lubricants, UV stabilizers, organic or inorganic scattering particles, and the like.

[0161] Furthermore, the present invention relates to moulded articles or semi-finished products such as foils, films or sheets produced from the above-described thermoplastic moulding compositions.

[0162] The thermoplastic molding compositions can be used for the production of any kind of moldings and semi-finished products such as sheets, films, fiber foams, etc. The processing can be carried out using known methods for thermoplastic processing, in particular the production can be carried out by thermoforming, (co)extrusion, injection molding, calendaring, blow molding, compression molding, press sintering, deep drawing or sintering, preferably by injection molding.

[0163] Molded or semi-finished products The present invention also relates to molded articles or semi-finished products produced from the inventive thermoplastic molding compositions described above.

[0164] For example, the molded article or semi-finished product may comprise the inventive thermoplastic molding composition as described above and further one or more additives as described above and / or one or more additional polymer components, for example the additives may be selected from dyes, pigments and crosslinked polymer beads.

[0165] Preferably, the molded article or semi-finished product comprises up to 50% by weight, preferably 0.0001% to 50% by weight, of at least one additive, preferably selected from dyes, pigments, organic scattering particles (in particular crosslinked polymer beads as described below) and inorganic scattering particles, based on the weight of the entire molded article or semi-finished product.

[0166] Preferably, the molded article or semi-finished product comprises up to 50% by weight, preferably 0.0001% to 50% by weight, of at least one dye and / or pigment, preferably selected from perinone dyes, quinophthalone dyes, anthraquinone dyes, azo dyes, inorganic pigments, phthalocyanine pigments and carbon black, based on the total weight of the molded article or semi-finished product.

[0167] Preferably, the moulded article or semi-finished product comprises from 0.01% to 50% by weight, relative to the total moulded article or semi-finished product, of at least one organic or inorganic scattering particle, preferably selected from crosslinked polymer beads, more preferably selected from crosslinked polymer beads (scattering beads) having a different refractive index compared to the refractive index of the polymer matrix formed by the thermoplastic moulding composition.

[0168] In a preferred embodiment, the semi-finished product is a film or sheet.

[0169] In a preferred embodiment, the molded or semi-finished product is transparent. In particular, the molded or semi-finished product has a haze value of 30.0% or less, preferably 20.0% or less, more preferably 10% or less, in particular 6.0% or less, for a material thickness of 40 μm to 1000 μm, determined after 4 h to 24 h water storage at 80 ° C., measured by a BYK Gardner Hazegard-plus haze meter in accordance with ASTM D1003-13. In particular, the molded or semi-finished product has a haze value of 30% or less, preferably 25.0% or less, more preferably 20.0% or less, for a material thickness of 1 mm, determined after 24 h water storage at 80 ° C., in accordance with ASTM D1003-13.

[0170] In particular, the molded article or semi-finished product is produced by providing a thermoplastic molding composition as described above, adding at least one additive, in particular at least one additive selected from the dyes, pigments and crosslinked polymer beads described above, and mixing the thermoplastic molding composition and the at least one additive, preferably via melt kneading, for example during a film-forming process or an injection molding process.

[0171] Typically, said dyes and / or pigments can be added to the above-described inventive thermoplastic molding composition in the form of a color preparation, a liquid composition comprising said color preparation or a masterbatch.

[0172] In some embodiments of the present invention, the molding composition may contain organic or inorganic scattering particles dispersed in the polymer matrix. The low haze value of the impact-modified thermoplastic molding composition of the present invention after hot water storage may be advantageous in combination with scattering particles, since it allows to obtain a more uniform opaque and matte appearance even after hot water storage. The choice of scattering particles is not particularly limited, but is typically selected such that the refractive index of the scattering particles differs from that of the copolymer matrix by at least 0.01. The refractive index can be measured at 23° C. at Na D radiation at 589 nm, as specified in standard ISO 489 (1999).

[0173] The scattering particles usually have an average particle size between 0.01 μm and 100.0 μm. The average particle size of the scattering particles is indicated as the so-called volume average d50 value (i.e. 50 volume percent of the particles have a particle size less than the stated average particle size) and can be measured according to the standard ISO 13320-1 (2009) for laser diffraction measurements. Typically, the size of the scattering particles is determined by laser light scattering using a Beckman Coulter LS 13 320 laser diffraction particle size analyzer, for example at room temperature, 23° C.

[0174] The inorganic scattering particles may include conventional inorganic opacifiers such as barium sulfate, calcium carbonate, titanium dioxide or zinc oxide.

[0175] The organic scattering particles are typically spherical scattering beads made of cross-linked polymeric materials such as polyalkyl(meth)acrylates, silicones, polystyrene, etc. Preferably, at least 70%, in particular at least 90%, of the scattering beads are spherical, relative to the number of scattering beads.

[0176] Preferred scattering beads comprised of cross-linked polystyrene are commercially available from Sekisui Plastics Co., Ltd. under the trademarks Techpolymer® SBX-4, Techpolymer® SBX-6, Techpolymer® SBX-8 and Techpolymer® SBX-12.

[0177] Other particularly preferred spherical plastic particles for use as scattering agents include crosslinked silicones. Particularly preferred silicone scattering agents for use in the present invention are available from Momentive Performance Materials Inc. as TOSPEARL® 120 and TOSPEARL® 3120.

[0178] In Figures 1-7, the coagulants and auxiliary materials used are specified in brackets, CaAc2 is calcium acetate, CaCl2 is calcium chloride, CaOH2 is calcium hydroxide, MgAc2 is magnesium acetate, MgSO4 is magnesium sulfate, Na2CO3 and NH3 indicate sodium carbonate and ammonia, and CaHyp2 is calcium hypophosphite Ca(H2PO2)2. [Brief description of the drawings]

[0179] [Figure 1] FIG. 1 shows the difference in haze (Δhaze) before and after 24 h of hot water storage at 80° C. for 1 mm press plates made from core-shell emulsion polymers (EP1-4) processed and dehydrated by freeze coagulation (EP1-3) or hot shear coagulation (EP4) as a function of the amount of sodium mNa given in mmol / kg (impact modifier). [Diagram 2] FIG. 1 shows the difference in haze (ΔHaze) before and after 24 h of hot water storage at 80° C. for 1 mm press plates made from a core-shell-shell emulsion polymer (EP5) processed by freeze coagulation followed by a blending step with PMMA as blend component (wIM=36 wt.%, wPMMA=64 wt.%) as a function of the amount of sodium mNa given in mmol / kg (impact modifier). [Diagram 3] FIG. 1 shows the difference in haze (ΔHaze) before and after 24 h of hot water storage at 80° C. for 1 mm press plates made from a core-shell-shell emulsion polymer (EP6) processed by freeze coagulation followed by a blending step with PMMA as blend component (wIM=33 wt.%, wPMMA=67 wt.%) as a function of the amount of sodium mNa given in mmol / kg (impact modifier). [Figure 4]FIG. 1 shows the difference in haze (Δhaze) before and after 24 h of hot water storage at 80° C. for 1 mm press plates made from core-shell emulsion polymers (EP1-4) processed by freeze coagulation (EP1-3) or hot shear coagulation (EP4) and dehydrated as a function of the molar ratio of sodium to calcium, magnesium, (calcium+magnesium) and aluminum, given in [mmol / kg(impact modifier)] / [mmol / kg(impact modifier)], respectively. [Diagram 5] FIG. 1 shows the difference in haze (ΔHaze) before and after 24 h of hot water storage at 80° C. for 1 mm press plates made from core-shell-shell emulsion polymer (EP5) processed by freeze coagulation and dehydration followed by blending with PMMA as blend component (wIM=36 wt.%, wPMMA=64 wt.%) as a function of the molar ratio of sodium to calcium and magnesium, respectively, given in [mmol / kg(impact modifier)] / [mmol / kg(impact modifier)]. [Figure 6] FIG. 1 shows the difference in haze (ΔHaze) before and after 24 h of hot water storage at 80° C. for 1 mm press plates made from core-shell-shell emulsion polymer (EP6) processed by freeze coagulation and dehydration followed by blending with PMMA as blend component (wIM=33 wt%, wPMMA=67 wt%) as a function of the molar ratio of sodium to calcium and magnesium, respectively, given in [mmol / kg(impact modifier)] / [mmol / kg(impact modifier)]. [Figure 7] FIG. 1 shows the reduction in polymer loss due to wastewater during extrusion dewatering while processing core-shell emulsion polymer EP4 by thermal shear coagulation (Examples 67-73) as a function of the molar ratio of sodium to calcium and magnesium, respectively, given in [mmol / kg(impact modifier)] / [mmol / kg(impact modifier)].

[0180] The reduction in polymer loss (wt%) was calculated as 1-wP / wP,0, where wP,0 is the amount of polymer in the wastewater of Reference Example 67 (without CaAc2 added) and wP is the amount of polymer in the wastewater of each example.

[0181] The invention is explained in more detail by the following examples and claims.

[0182] Working Example overview Emulsion polymers EP1, EP2 and EP3 with a core-shell structure were prepared and freeze-coagulated (examples 1-40). Emulsion polymers EP5 and EP6 with a core-shell-shell structure were prepared and freeze-coagulated (examples 41-61). Furthermore, the core-shell emulsion polymer EP1 was processed by thermal and freeze-coagulation and mechanical dehydration (centrifugation) (examples 62-66). The core-shell emulsion polymer EP4 (examples 67-73) and the core-shell-shell emulsion polymer EP5 (examples 74-79) were processed by successive thermal shear coagulation and mechanical dehydration extrusion. In general, the core-shell-shell emulsion polymers were then blended with PMMA.

[0183] Unless stated otherwise, different coagulation agents (coagulation agents) were added before or after coagulation, in particular before coagulation, as mentioned, calcium, magnesium or aluminium salts.

[0184] The amount of metal ion in the emulsion polymer was determined as described below. Additionally, test specimens were prepared and haze values ​​were determined as described below. The results are summarized in the table below.

[0185] Table 2 (examples 1-40) contains the results for core-shell emulsion polymers EP1, EP2, and EP3, processed by freeze-coagulation and mechanical dehydration (centrifugation). Unless otherwise stated, the coagulant (coagulation agent) was added before freezing. Table 4 (examples 41-56) contains the results for the core-shell-shell emulsion polymer EP5, processed by freeze-coagulation and mechanical dehydration (centrifugation) and subsequently blended with PMMA (polymethylmethacrylate). Unless otherwise stated, the coagulant (clotting agent) was added prior to freezing. Table 5 (examples 57-61) contains the results for the core-shell-shell emulsion polymer EP6, processed by freeze-coagulation and mechanical dehydration (centrifugation) and subsequently blended with PMMA. Unless otherwise stated, the coagulant (coagulation agent) was added prior to freezing. Table 6 (Examples 62-66) contains results for the core-shell emulsion polymer EP4, processed by heat and freeze coagulation, and mechanical dehydration (centrifugation). Unless otherwise stated, the coagulant (coagulation agent) was added prior to freezing. Table 7 (Examples 67-73) contains results for the core-shell emulsion polymer EP4 processed by sequential thermal shear coagulation and mechanical dewatering extrusion. The examples are listed in chronological order of the tests performed. Table 8 (Examples 74-79) contains results for the core-shell-shell emulsion polymer EP5 processed by successive thermoshear coagulation and mechanical dewatering extrusion, followed by blending with PMMA. The examples are listed in chronological order of the tests performed.

[0186] I. Examples 1-40 / Freeze coagulation of emulsion polymers EP1, EP2 and EP3 (core-shell polymers) Ia. Preparation of PMMA latex emulsion polymers EP1, EP2 and EP3 Into a polymerization vessel equipped with an agitator, a feed vessel and external cooling was placed an aqueous phase containing sodium hydroxymethyl sulfate, acetic acid, iron(II) sulfate (FeSO4), and an aqueous seed latex solution having 5% solids by weight.

[0187] At a temperature of 55° C. (outside the vessel), emulsion I as described in Table 1 was added continuously over a period of 20 minutes. After 10 minutes, emulsion II as described in Table 1 was added successively within 2 hours. The reaction mixture was stirred for 60 minutes, cooled to 45° C. and filtered through VA steel (mesh size 90 μm). Emulsions I and II were obtained by emulsifying the monomers and components, respectively, as shown in Table 1.

[0188] The amounts are summarized in Table 1 below.

[0189] [Table 1]

[0190] The resulting aqueous polymer dispersion had a solids content of 40-42% by weight.

[0191] Ion exchange According to Example 22, the emulsion polymer EP1 was subjected to an ion exchange step. A glass column with an internal diameter of 16 mm was filled with 25 mL of a strongly acidic ion exchanger (Dowex Marathon C) in the protonated form (H-form). The free volume above the ion exchanger bed was manually filled with the aqueous emulsion polymer EP1. The emulsion was then pumped through the column from top to bottom with a mass flow rate of 2.5 g / min. A sample was taken at the column outlet and analyzed by AAS. The sodium content of the dispersion was less than 10 ppm. All examples were frozen, sintered and dehydrated as described in section Ib. below.

[0192] Ib. Solidification, sintering and dehydration To coagulate the above emulsion polymers EP1, EP2, EP3, an aqueous solution of a metal salt (coagulant) was added at room temperature with stirring within 1-2 minutes (in the examples with added coagulant). After the latex was completely coagulated, the dispersion was frozen at -18°C for 24 hours. According to the comparative example (no coagulant added), the emulsion polymer was frozen without adding a metal salt solution. In comparative examples 18 and 19, different amounts of Ca(Ac)2 were added after freeze-coagulation.

[0193] The mixture was then sintered at 80 °C for 24 h. The latex was cooled to room temperature and the particles were separated from the water by centrifugation at 1800 rpm. Centrifugation times were varied between 1.5 and 10 min to obtain different residual water contents (w(H2O)) in the coagulated and dehydrated emulsion polymer.

[0194] The water content after centrifugation (w(H2O)) was determined using an electronic moisture analyzer (Sartorius MA45). The results are summarized in Table 2 below.

[0195] After centrifugation, the polymer was washed with deionized water (1 L) and centrifuged again. This procedure was performed three times and the resulting polymer powder was dried at 50 °C for about 16-48 h to obtain a final moisture content of less than 1%. Test specimens of 1 mm thickness were prepared from the dried material as described below.

[0196] The metal ion contents (e.g., sodium content, calcium content, and magnesium content) of the dehydrated and dried impact modifiers (emulsion polymers) of Examples 1 to 40 were determined as follows. The results are summarized in Table 2.

[0197] Aqueous solutions of calcium acetate CaAc2, calcium hydroxide Ca(OH)2, calcium chloride CaCl2, magnesium sulfate MgSO4, magnesium acetate MgAc2, aluminum sulfate Al2(SO4)3, calcium hypophosphite Ca(H2PO2)2 and ammonia NH3 were used as coagulants. For example, CaAc2 was used as an aqueous solution containing 1 wt%, 10 wt% or 15 wt% CaAc2. The amount of coagulant added to the emulsion polymer latex before or after coagulation is summarized in the table below and is given as molar metal ion (e.g., Ca or Mg) relative to the molar amount of sodium in the aqueous polymer dispersion. The sodium content in the aqueous polymer dispersion was in the range of 0.012-0.05 wt% with respect to the total aqueous polymer dispersion. The sodium content results from auxiliaries added during emulsion polymerization, such as emulsifiers, reducing agents, initiators or buffers used for pH adjustment, and was calculated based on the amount of said auxiliaries added during polymerization.

[0198] Ic. Preparation of molding compositions and test specimens The dehydrated and dried impact modifiers (emulsion polymers) according to examples 1-40 (based on emulsion polymers EP1, EP2, EP3) were compounded to obtain polymer granules. A single screw extruder with a diameter of 30 mm was used to melt and mix the polymers. The melt temperature was 235°C. The extrudate emerging from the extruder die was cooled in a water bath and pelletized.

[0199] Test specimens 1 mm thick and 5 cm in diameter were prepared by hot pressing the granules obtained as described above. The haze and transmittance of the test specimens were determined as described below. The results are summarized in Tables 2 and 2a (transmittance) below.

[0200] [Table 2]

[0201] [Table 3]

[0202] [Table 4]

[0203] [Table 5]

[0204] [Table 6]

[0205] [Table 7]

[0206] [Table 8]

[0207] It has been shown that improved hot water storage stability in terms of haze and transmittance is obtained when the amount of sodium is reduced to 3 mmol / kg or less, preferably below 2 mmol / kg, while the molar ratio of alkali metal ions to multivalent ions (attributed to the coagulant) is 1.3 mol / mol or less. This is also shown in Figures 1 and 4, where the results from Examples 1 to 40 are summarized.

[0208] II. Examples 41-61 - Freeze coagulation of emulsion polymers EP5 and EP6 (core-shell-shell emulsion polymers) IIa. Preparation of PMMA latex emulsion polymer Emulsion polymer EP5 was prepared as follows.

[0209] In a polymerization vessel equipped with a stirrer, a feed vessel and external cooling, an aqueous phase containing acetic acid, iron (II) sulfate (FeSO4) and seeds, and containing 10 weight percent PMMA, was placed. At a temperature of 52° C. (external vessel temperature), emulsion I described in Table 3 was added over 1 hour. In parallel, 0.69 g of sodium metabisulfite in 20 g of water was added (first 10 minutes). After 15 minutes, in parallel with the start of the addition of emulsion II described in Table 3, 1.94 g of sodium metabisulfite in 100 g of water was added within 10 minutes. Emulsion II (Table 3) was added within 2 hours, followed by a pause of 50 minutes. Emulsion III described in Table 3 was added simultaneously with 0.62 g of sodium metabisulfite in 50 g of water. The addition of sodium metabisulfite was completed within 10 minutes and emulsion III after 1 hour. The reaction mixture was then stirred for 30 min, cooled to 35° C. and filtered through VA steel (mesh size 100 μm).

[0210] Emulsion polymer EP6 was prepared as follows.

[0211] In a polymerization vessel equipped with a stirrer, a feed vessel and external cooling, water, sodium carbonate and seeds containing 10 weight percent PMMA were placed. At a temperature of 83°C (vessel temperature), emulsion I, as described in Table 3, was added over 90 minutes (10 minutes addition, 10 minutes pause, 80 minutes addition). After a 10 minute pause, the addition of emulsion II, as described in Table 3, was started. Emulsion II was added within 2 hours, followed by a pause of 30-45 minutes. Emulsion III was added within 1 hour. The reaction mixture was then stirred for 30 minutes, cooled to room temperature (approximately 30 minutes) and filtered through VA steel (mesh size 100 μm).

[0212] Emulsions I, II and II were obtained by emulsifying the monomers and components shown in Table 3, respectively.

[0213] [Table 9]

[0214] The resulting aqueous polymer dispersions had solids contents of 46-48 wt % (EP5) and 49-51 wt % (EP6).

[0215] IIb. Solidification, sintering and dehydration Emulsion polymers EP5 and EP6 were processed as described above in Ib.

[0216] IIc. Preparation of molding compositions and test specimens A Haake Rheomix 5000 measuring mixer 30 was used to compound the dehydrated and dried impact modifiers (emulsion polymers) according to examples 41-61 (based on emulsion polymers EP5, EP6). 42-45 g of a polymer mixture consisting of polymethyl methacrylate PMMA_1 (a copolymer of about 96% by weight of methyl methacrylate (MMA) and 4% by weight of methyl acrylate with a weight average molecular weight of about Mw=110.000) and impact modifier (amounts see table below) were slowly added to the mixing chamber. The amount of impact modifier (w(IM)) is given in tables 4 and 5. The polymer blend was mixed (30 rpm) for 10 minutes at a temperature of 220-230 °C. The resulting melt was removed from the chamber and crushed with pliers.

[0217] Test specimens 1 mm thick and 5 cm in diameter were prepared by hot pressing the granules obtained as described above. The haze and transmittance of the test specimens were determined as follows. The results are summarized in Tables 4, 4a and 5 below.

[0218] Table 4 (Examples 41-56) and Table 5 (Examples 57-61) contain results for the core-shell-shell emulsion polymers EP5 and EP6, which were processed by freeze coagulation and mechanical dehydration (centrifugation) and subsequently blended with polymethyl methacrylate PMMA_1. Unless otherwise stated, the coagulant was added prior to freezing.

[0219] The water content of the emulsion polymer obtained after coagulation and dehydration is designated w(HO). The amount of coagulant added is expressed as the amount of polyvalent metal cation (e.g., Ca(add)) relative to the amount of sodium in the aqueous emulsion polymer composition, e.g., in mol Ca / mol Na The amount of impact modifier (emulsion polymer) in each molding composition in the test specimens used for haze and transmittance is indicated as w(IM) given in weight %. The amount of metal ions in the impact modifier (dry emulsion polymer) is given as mmol / kg(impact modifier).

[0220] [Table 10]

[0221] [Table 11]

[0222] [Table 12]

[0223] In Example 41, the coagulated emulsion polymer was isolated without a washing step and without centrifugation, i.e., the polymer was separated from the water by filtration only.

[0224] In Example 42, the coagulated emulsion polymer was separated by centrifugation for 15 seconds without a washing step, and in Example 43, the coagulated emulsion polymer was separated by centrifugation for 10 minutes without a washing step.

[0225] Examples 52-54 were prepared as described in EP5. Prior to coagulation, the pH of the dispersion was adjusted to pH 6.5-7 using sodium carbonate and, if necessary, ammonia solution. Coagulation, sintering and dehydration were carried out according to the procedures described.

[0226] [Table 13]

[0227] It has been shown that by reducing the amount of sodium to 3 mmol / kg or less, preferably below 2 mmol / kg, while at the same time the molar ratio of alkali metal ions to multivalent ions (attributed to the coagulant) is 1.3 mol / mol or less, improved hot water storage stability in terms of haze and transmittance is obtained. This is also shown in Figures 2, 3 and 5, 6, where the results from Examples 41 to 61 are summarized.

[0228] III. Examples 62-66 (Preparation of PMMA impact modifiers processed by heat coagulation and freeze coagulation) IIIa. Preparation of PMMA latex emulsion polymer Core-shell emulsion polymer EP4 (impact modifier for PMMA molding compounds) formed in two stages as described above for EP1-EP3, the following compositions were processed: Step I: Butyl acrylate / allyl methacrylate in a ratio of 98:2 Stage II: Methyl methacrylate / butyl acrylate / dodecyl mercaptan in the ratio 92:8:0.8

[0229] Mass ratio of I / II = 33.4 / 66.6 Mass ratio of polymer phase / water phase=41 / 59 Average particle size: approx. 124nm

[0230] IIIb. Solidification, sintering and dehydration Coagulation was performed as described below: Example 62 A 25 L stainless steel stirred vessel was filled with 15 kg of aqueous emulsion polymer EP4 and heated while stirring with a blade stirrer at 97 rpm. During the heating phase, a stainless steel pressure cylinder was connected to the stirred vessel via a ball valve. The cylinder contained 62.6 g of a 15 wt. % MgSO4 aqueous solution and 62.6 g of a 1 wt. % ammonia aqueous solution. The cylinder was pressurized with nitrogen to a pressure higher than the internal pressure of the stirred vessel. When an internal temperature of 106° C. was reached in the vessel, the ball valve was opened and the cylinder contents were rapidly introduced into the dispersion by the pressure difference. The dispersion was then stirred for a further 57 minutes with continued heating, during which the internal temperature rose to 133° C. The contents of the vessel were then cooled and the vessel was opened. The vessel contained the solidified dispersion and a milky white aqueous phase.

[0231] Example 63 A 25 L stainless steel stirred vessel was filled with 15 kg of aqueous emulsion polymer EP4 and heated while stirring with a blade stirrer at 111 rpm. During the heating phase, a stainless steel pressure cylinder was connected to the stirred vessel via a ball valve. The cylinder contained 62.8 g of a 15 wt.% MgSO4 aqueous solution and 62.7 g of a 1 wt.% ammonia aqueous solution. The cylinder was pressurized with nitrogen to a pressure higher than the internal pressure of the stirred vessel. When an internal temperature of 152°C was reached in the vessel, the ball valve was opened and the cylinder contents were rapidly introduced into the dispersion by the pressure difference. The dispersion was then stirred for a further 82 minutes with continued heating, during which the internal temperature rose to 153°C. The contents of the vessel were then cooled and the vessel was opened. The vessel contained the solidified dispersion and a milky white aqueous phase.

[0232] Example 64 A 2.4 L stainless steel stirred vessel was filled with 2004 g of aqueous emulsion polymer EP4 and heated with stirring at 150 rpm with a three-stage INTERMIG stirrer. During the heating phase, a stainless steel pressure-resistant cylinder was connected to the stirred vessel via a ball valve. The cylinder contained 8.4 g of a 15 wt. % MgSO4 aqueous solution and 8.4 g of a 1 wt. % ammonia aqueous solution. The cylinder was pressurized with nitrogen to a pressure higher than the internal pressure of the stirred vessel. When an internal temperature of 195° C. was reached in the vessel, the ball valve was opened and the cylinder contents were rapidly introduced into the dispersion by the pressure difference. The dispersion was then stirred for a further 10 minutes with continued heating, during which the internal temperature rose to 209° C. The contents of the vessel were then cooled and the vessel was opened. The vessel contained the solidified dispersion and a milky white aqueous phase.

[0233] Example 65 A 2.4 L stainless steel stirred vessel was filled with 2008 g of the aqueous emulsion polymer EP4 and heated while stirring with a blade stirrer at 150 rpm. During the heating phase, a stainless steel pressure cylinder was connected to the stirred vessel via a ball valve. The cylinder contained 8.5 g of a 15 wt. % MgSO4 aqueous solution and 8.7 g of a 1 wt. % ammonia aqueous solution. The cylinder was pressurized with nitrogen to a pressure higher than the internal pressure of the stirred vessel. When an internal temperature of 223° C. was reached in the vessel, the ball valve was opened and the cylinder contents were rapidly introduced into the dispersion by the pressure difference. The dispersion was then stirred for a further 10 minutes with continued heating, during which the internal temperature rose to 224° C. The contents of the vessel were then cooled and the vessel was opened. The vessel contained the solidified dispersion and a milky white aqueous phase.

[0234] Example 66 A 2.4 L stainless steel stirred vessel was filled with 2000 g of the aqueous emulsion polymer EP4 and heated while stirring with a blade stirrer at 150 rpm. During the heating phase, a stainless steel pressure cylinder was connected to the stirred vessel via a ball valve. The cylinder contained 8.95 g of a 15 wt.% MgSO4 solution in water. The cylinder was pressurized with nitrogen to a pressure higher than the internal pressure of the stirred vessel. When an internal temperature of 195°C was reached in the vessel, the ball valve was opened and the cylinder contents were rapidly introduced into the dispersion by the pressure difference. The dispersion was then stirred for a further 10 minutes with continued heating, during which the internal temperature rose to 210°C. The contents of the vessel were then cooled and the vessel was opened. The vessel contained the solidified dispersion and a milky white aqueous phase.

[0235] All examples were frozen, sintered, and dehydrated as described in Section Ib.

[0236] IIIc. Preparation of molding compositions and test specimens Dehydrated and dried impact modifiers (emulsion polymers) (based on emulsion polymer EP4) according to Examples 62-66 were compounded as described in Section Ic. Test specimens 1 mm thick and 5 cm in diameter were prepared by hot pressing the granules as described in Section Ic. The results are summarized in Table 6 below.

[0237] [Table 14]

[0238] IV. Examples 67-73 (Preparation of PMMA impact modifiers using thermal shear coagulation) IVa. Preparation of PMMA latex emulsion polymer The core-shell emulsion polymer EP4 described above (Section IIIa.) was used.

[0239] IVb. Solidification, sintering and dehydration Different amounts of calcium acetate (CaAc2) were added to the emulsion polymer latex EP4 in the form of an aqueous solution (1 wt%, 10 wt% or 15 wt%), followed by shear coagulation. Calcium acetate (CaAc2) was added in an amount of 0.1-2 mol Ca relative to the molar amount of sodium in the aqueous polymer dispersion (see Ca(add) in Table 7). The amount of sodium in the aqueous dispersion was about 0.013 wt% relative to the aqueous dispersion. The sodium content originates from auxiliary agents added during emulsion polymerization, such as emulsifiers, reducing agents, initiators or buffers used for pH adjustment, and was calculated based on the amount of said auxiliary agents added during polymerization.

[0240] The latex was pumped into the barrel (zone 1) of a counter-rotating twin-screw extruder. The coagulation zone was divided into several main zones, starting with the first zone where the dispersion was fed into the extruder. The designated temperature of the heat jacket of the coagulation zone in the extruder was in the range of 150-210°C. The last zone was followed by a dewatering zone, which separated the polymer melt.

[0241] Via a line, a collection tank for separated water was maintained under a pressure of at least 28 bar. A water stream, typically containing 8-10% polymer, was withdrawn via a valve. The feed stream to the degassing extruder was regulated by a valve such that the melt pressure was maintained at 40-60 bar.

[0242] In the degassing extruder, residual amounts of volatile components are separated from the polymer. The extruded or granulated material discharged from the granulation nozzle has a residual moisture content of less than 5% by weight.

[0243] The polymer concentration in the water collected in the dewatering zone was analyzed with an electronic moisture analyzer HE53 from Mettler Toledo heated to 160° C. The results (see Table 7 below) are given based on the % reduction in polymer loss with respect to reference example Ex67 (without CaAc2 added). The reduction in polymer loss (Red.Loss) given in weight % is: Red.Loss(weight%)=1-w P,A / w P,A,0 where w P,A,0 is the amount of polymer in the wastewater of Reference Example 43 (without CaAc2 addition), and w P,A is the amount of polymer in the wastewater for each example.

[0244] IVc. Preparation of molding compositions and test specimens Test specimens with a thickness of 1 mm and a diameter of 5 cm were prepared by hot pressing the granules obtained after the extrusion process. The haze of the test specimens before and after hot water storage, as well as the amount of sodium and calcium in the dried emulsion polymer, were determined as follows:

[0245] The results are summarized in Table 7, and the examples are shown in chronological order. First, emulsion polymer latex EP4 without CaAc2 was fed into the extruder, followed by emulsion polymer latex A4 with CaAc2 solutions having 10% by weight and 15% by weight (in that order). Then, emulsion polymer latex EP4 without CaAc2 was fed. After a stable process was reached, samples were taken.

[0246] It has been shown that reducing the amount of sodium to 3 mmol / kg or less, while at the same time maintaining the molar ratio of alkali metal ions to multivalent ions (attributed to the coagulant) at 1.3 mol / mol or less, results in improved hot water storage stability. This is also shown in Figure 7, where the results from Examples 67-73 are summarized.

[0247] It has been shown that the reduction in polymer losses (Red.Loss (wt%), see above) is significantly improved by about 90% when the molar ratio of sodium to calcium is less than 1.3. In particular, these advantageous results are obtained when the amount of sodium in the emulsion polymer is less than 3 mmol / kg and the amount of calcium is more than 2 mmol / kg.

[0248] [Table 15]

[0249] V. Examples 74-79 (Preparation of PMMA impact modifiers using thermal shear solidification) Va. Preparation of PMMA latex emulsion polymer The core-shell emulsion polymer EP5 was prepared as described above (section IIa.).

[0250] Vb. Solidification, sintering and dehydration The coagulation and dehydration of emulsion polymer EP5 was prepared as described above for Examples 67-73 (Section IVb.). The emulsion polymer EP5 was processed by thermal shear coagulation and mechanical dehydration extrusion, and then blended with polymethyl methacrylate PMMA_1.

[0251] Vc. Preparation of molding compositions and test specimens Test specimens 1 mm thick and 5 cm in diameter were prepared by hot pressing the granules obtained after the extrusion process as described above for Examples 67-73 (Section IVc.). The haze of the test specimens before and after hot water storage, as well as the amount of sodium and calcium in the dried emulsion polymer, were determined as follows. The results are summarized in Table 8, with the examples presented in chronological order.

[0252] [Table 16]

[0253] VI. Testing Method VIa. Hot water haze Test specimens (obtained by hot pressing, 1 mm thick, 5 cm diameter) were stored for 24 h in deionized water at 80° C. Haze values ​​were determined before and after hot water storage according to ASTM D1003-13 using a haze meter BYK Gardner haze-gard i.

[0254] These specimens, prepared as described above, were tested at 23°C using a BYK Gardner haze-gard i haze meter in accordance with ASTM D1003-13, both in their original state ("pre-haze") and after 24 hours of hydrothermal storage in 80°C deionized water. It is noted that materials with haze values ​​greater than 30% (according to ASTM D1003-13) are considered "diffuse" and should be tested in accordance with the Goniometric Optical Scattering Measurement Practice (E2387). As the focus of this study is on transparent materials with haze values ​​less than 30%, haze values ​​greater than 30% are reported to illustrate trends.

[0255] These haze values ​​and the difference in haze values ​​before and after storage in hot water (haze / Δ) (haze / 24h-haze / 0h) are summarized in the table above.

[0256] The transmittance (given in %) before and after hot water storage was determined accordingly according to ASTM D1003-13.

[0257] VIb. Metal ion content To determine the metal ion content (e.g., Na and Ca), microwave-assisted digestion of the dried emulsion polymer with nitric acid was performed, after which the content of related ions was determined by atomic absorption spectroscopy.

[0258] VIc. Water content Unless otherwise specified, moisture content (residual water) was determined using an electronic moisture analyzer (Sartorius MA45) heated to 85° C. Reduction in polymer loss was determined as in Section IVb. Coagulation, sintering, and dehydration above.

Claims

1. A poly(meth)acrylate impact modifier comprising at least one polyphase alkyl(meth)acrylate emulsion polymer, wherein the poly(meth)acrylate impact modifier comprises at least one polyvalent metal ion and alkali metal ions at a concentration of 3.0 mmol / kg or less relative to the solid content of the impact modifier, and the molar ratio of alkali ions to polyvalent metal ions is 1.3 or less.

2. The poly(meth)acrylate impact modifier according to claim 1, characterized in that the molar ratio of polyvalent metal ions to alkali ions is 0.8 or higher, preferably 0.9 or higher.

3. The poly(meth)acrylate impact modifier according to claim 1, characterized in that it contains 0.5 mmol / kg or more of polyvalent metal ions relative to the solid content of the impact modifier.

4. The poly(meth)acrylate impact modifier according to claim 1, characterized in that it contains 0 to 3.0 mmol / kg of alkali metal ions and 0.5 to 20.0 mmol / kg of polyvalent metal ions relative to the solid content of the impact modifier.

5. The poly(meth)acrylate impact modifier according to claim 1, characterized in that the alkali metal ion is selected from sodium and potassium, and the polyvalent metal ion is selected from alkaline earth metals, zinc, calcium, magnesium, and aluminum ions.

6. The poly(meth)acrylate impact modifier according to claim 1, characterized in that the polyphase alkyl (meth)acrylate emulsion polymer is obtained by emulsion polymerization and comprises a core and at least one, preferably one or two, shells.

7. The aforementioned polyphase alkyl (meth)acrylate emulsion polymer At least 10% by weight, preferably at least 20% by weight, of at least one C1-C10 alkyl methacrylate, 5 to 80% by weight, preferably 20 to 80% by weight, at least one C1 to C10 alkyl acrylate or at least one conjugated diene, 0 to 2% by weight, preferably 0.1 to 2% by weight, at least one crosslinkable monomer, A further monomer, preferably vinyl aromatic monomer, in the case of 0 to 15% by weight, preferably 0.5 to 10% by weight. The poly(meth)acrylate impact modifier according to claim 1, characterized by containing the following.

8. The aforementioned polyphase alkyl (meth)acrylate emulsion polymer A1) 10 to 95% by weight of the total emulsion polymer, with a glass transition temperature T of less than -10°C. ｇ It has, A1.1) At least one type of C in an amount of 50 to 99.5% by weight relative to A1. １ ~C １０ Alkyl acrylate, preferably n-butyl acrylate, A1.2) 0.5 to 5% by weight of A1, at least one crosslinkable monomer having two or more ethylenically unsaturated groups, and A1.3) 0 to 10% by weight of at least one further ethylenically unsaturated free radical polymerizable monomer relative to A1. A soft elastomer core A1 is constructed from, B1) 5 to 90% by weight of the total emulsion polymer, with a glass transition temperature T above 70°C ｇ It has, B1.1) At least one type of C in an amount of 80 to 100% by weight relative to B1 １ ~C ６ Alkyl methacrylate, preferably methyl methacrylate, and B1.2) At least one further ethylenically unsaturated free radical polymerizable monomer in an amount of 0 to 20% by weight relative to B1. The rigid shell B1 is constructed from and The poly(meth)acrylate impact modifier according to claim 1, characterized in that it is a core-shell emulsion polymer containing the above.

9. The aforementioned polyphase alkyl (meth)acrylate emulsion polymer A2) 5 to 40% by weight of the total emulsion polymer, with a glass transition temperature T above 50°C ｇ It has, A2.1) At least one C of 80 to 100% by weight with respect to A2 １ ~C ６ alkyl methacrylate, preferably methyl methacrylate, A2.2) At least one further ethylenically unsaturated free radical polymerizable monomer in an amount of 0 to 20% by weight relative to A2, and A2.3) At least one crosslinkable monomer having two or more ethylenically unsaturated groups, in an amount of 0 to 5% by weight relative to A1. A rigid non-elastomer core A2 is constructed from, B2) 20 to 75% by weight of the total emulsion polymer, with a glass transition temperature T of less than 0°C. ｇ It has, B2.1) At least one type of C in an amount of 45 to 99.5% by weight relative to B2. １ ~C １０ Alkyl acrylate, preferably n-butyl acrylate, B2.2) 0.5 to 5% by weight of B2, at least one crosslinkable monomer having two or more ethylenically unsaturated groups, and B2.3) 0 to 50% by weight of at least one further ethylenically unsaturated free radical polymerizable monomer, preferably a monomer having an aromatic group, relative to B2. A soft elastomer intermediate shell B2 is constructed from, C2) 15 to 60% by weight of the total emulsion polymer, with a glass transition temperature T above 50°C ｇ It has, C2.1) At least one C2 in an amount of 80 to 100% by weight, preferably 90 to 100% by weight. １ ~C ６ Alkyl methacrylate, preferably methyl methacrylate, and C2.2) At least one further ethylenically unsaturated free radical polymerizable monomer in an amount of 0 to 20% by weight, preferably 0 to 10% by weight, relative to C2. The rigid outer shell C2 is constructed from and The poly(meth)acrylate impact modifier according to claim 1, characterized in that it is a core-shell-shell emulsion polymer containing the above.

10. (i) A preparation step of at least one polyphase alkyl (meth)acrylate emulsion polymer by emulsion polymerization, wherein the polyphase alkyl (meth)acrylate emulsion polymer is obtained in the form of latex, (ii) Coagulation and dehydration of the latex obtained in step (i), preferably a mechanical dehydration step, wherein the coagulation is performed by physical coagulation, a dehydrated alkyl (meth)acrylate emulsion polymer is obtained, the dehydrated alkyl (meth)acrylate emulsion polymer contains alkali metal ions of 3.0 mmol / kg or less, preferably 2.5 mmol / kg or less, relative to the solid content of the alkyl (meth)acrylate emulsion polymer, and the molar ratio of alkali ions to polyvalent metal ions in the dehydrated alkyl (meth)acrylate emulsion polymer is 1.3 or less, preferably 1.2 or less, wherein the coagulation and dehydration, preferably a mechanical dehydration step It includes, A coagulant containing a salt of at least one polyvalent metal ion is added to the emulsifying polymer before and / or during coagulation. A method for producing a poly(meth)acrylate impact modifier according to claim 1, comprising at least one polyphase alkyl (meth)acrylate emulsion polymer.

11. The method according to claim 10, characterized in that the dehydrated alkyl (meth)acrylate emulsion polymer obtained in step (ii) contains 0 to 3.0 mmol / kg of alkali metal ions and 0.5 to 20.0 mmol / kg of polyvalent metal ions relative to the solid content of the emulsion polymer.

12. The method according to claim 10, characterized in that the coagulant is an aqueous solution of a salt of at least one polyvalent metal ion selected from alkaline earth metals, zinc, calcium, magnesium, and aluminum.

13. In step (ii), the solidification is carried out by freeze-solidification, the mechanical dehydration of the solidified emulsion polymer is carried out by centrifugal separation, and the water content of the dehydrated emulsion polymer is in the range of 5 to 40% by weight, preferably 7 to 30% by weight, relative to the dehydrated emulsion polymer. (iii) Depending on the circumstances, wash the dehydrated alkyl (meth)acrylate emulsion polymer. The method according to claim 10, comprising (iv) drying the dehydrated alkyl (meth)acrylate emulsion polymer obtained in step ii) or iii), characterized in that the poly(meth)acrylate impact modifier is obtained as a polymer powder.

14. The method according to claim 10, characterized in that in step (ii), the coagulation and mechanical dehydration are carried out by thermal shear coagulation, the latex obtained in step (i) is introduced into an extrusion line having at least one coagulation zone, at least one dehydration zone and at least one degassing zone, and the poly(meth)acrylate impact modifier is obtained as polymer granules.

15. A thermoplastic molding composition, The molding composition contains 1 to 100% by weight, preferably 5 to 100% by weight, of at least one poly(meth)acrylate impact modifier according to claim 1, The molding composition contains 0 to 99% by weight, preferably 0 to 95% by weight, of at least one thermoplastic (meth)acrylate polymer, preferably poly(methyl methacrylate), relative to the entire composition. The molded composition contains 0 to 50% by weight, preferably 0 to 10% by weight, of one or more additives and / or one or more additional polymer components. A thermoplastic molding composition containing the following:

16. xi) Mixing 1 to 100% by weight, preferably 5 to 100% by weight, of the entire thermoplastic molding composition with at least one poly(meth)acrylate impact modifier according to claim 1, 0 to 99% by weight, preferably 0 to 95% by weight, of at least one thermoplastic (meth)acrylate polymer, and optionally 0 to 50% by weight, preferably 0 to 10% by weight, of another additive and / or one or more additional polymer components. xi) Melt kneading of the mixture obtained in step xi) A method for producing the thermoplastic molding composition according to claim 15, including the method described above.

17. A molded article or semi-finished product manufactured from the thermoplastic molding composition described in claim 15.

18. The entire molded article or semi-finished product is enriched with at least one additive selected from dyes, pigments, organic scattering particles, and inorganic scattering particles, in an amount of up to 50% by weight, preferably 0.0001% to 50% by weight. A molded article or semi-finished product according to claim 17, characterized by including the following:

19. A molded article or semi-finished product according to claim 17, characterized in that, after being stored in water at 80°C for 24 hours in accordance with ASTM D1003-13, it has a haze value of 25.0% or less, preferably 20.0% or less, with respect to a material thickness of 1 mm.

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