Flame retardant acrylic powder composition

Abstract

A multi-stage acrylic composition includes a first-stage acrylic polymer and a final-stage acrylic polymer formed on or around the first-stage acrylic polymer. The first-stage acrylic polymer comprises a structural unit of at least one organophosphorus monomer. The multi-stage acrylic composition is in powder form.

Description

Technical Field

[0001] The present invention generally relates to a multi-stage acrylic polymer composition useful as an impact modifier. The composition contains an organophosphorus monomer in the first stage of the multi-stage acrylic polymer. Background Art

[0002] Acrylic impact modifiers are typically prepared in the form of core-shell rubbers (CSRs) having a soft acrylic core covered with a harder graft shell.Core-shell rubber acrylic impact modifiers are typically prepared by conventional emulsion polymerization and isolated as a powder.

[0003] Acrylic impact modifiers can be used in a variety of thermoplastics, including polycarbonate (PC).

[0004] It has long been desired to introduce flame retardant moieties, molecules or atoms into acrylic impact modifiers. However, such efforts have met with limited success due to the difficulties associated with introducing such flame retardant moieties, molecules or atoms.

[0005] US Patent No. 11,254,990 discloses a composition comprising an aqueous dispersion of submicron-sized particles and micron-sized polymer beads, wherein one or both of the polymer particles or beads are functionalized with phosphoric acid groups. However, the composition is an aqueous dispersion rather than a powder.

[0006] European Patent No. EP 2 235 077 B1 discloses an aqueous composition comprising an emulsion polymer composition containing a phosphorus-containing monomer.

[0007] US Patent No. 7,820,754 discloses an aqueous polymer composition obtained from a monomer mixture including at least one ethylenically unsaturated monomer carrying at least one second functionality selected from phosphate, phosphonate or phosphite.

[0008] US Patent No. 7,803,858 discloses an aqueous composition comprising pigment particles, acrylic polymer particles containing phosphate or phosphonate groups, and at least one compound containing a pyrophosphate bond and having no more than 12% carbon.

[0009] Each of these prior art attempts provides an aqueous composition rather than a powder.

[0010] It would be desirable to provide a flame retardant multi-stage acrylic composition in powder form. Summary of the invention

[0011] One aspect of the present invention provides a multi-stage acrylic composition, the multi-stage acrylic composition comprising: (a) a first-stage polymer, wherein the first-stage polymer comprises structural units of at least one organic phosphorus monomer; and (b) a final-stage polymer formed on or around the first-stage acrylic polymer. The multi-stage acrylic composition is in powder form.

[0012] In another aspect, the present invention provides a matrix resin composition comprising (A) a multi-stage acrylic composition comprising: (a) a first-stage polymer, wherein the first-stage polymer comprises structural units of at least one organophosphorus monomer; and (b) a final-stage polymer formed on or around the first-stage acrylic polymer; and (B) one or more matrix resins. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The figure is a graph showing the total burn time after ignition for polycarbonate formulations according to embodiments of the present invention. DETAILED DESCRIPTION

[0014] The inventors have surprisingly found that incorporating an organophosphorus monomer in the first stage of a multi-stage acrylic polymer can improve the flammability of the acrylic polymer. In addition, the inventors have found that the multi-stage acrylic polymer can be formed into a powder and provide the desired impact resistance when used in a resin such as polycarbonate.

[0015] As used herein, the term "polymer" refers to a polymeric compound prepared by polymerizing monomers of the same or different types. The general term "polymer" includes the terms "homopolymer", "copolymer", "terpolymer" and "resin". As used herein, the term "structural unit" refers to the residue of the monomer after polymerization. As used herein, the term "(meth)acrylate" refers to acrylate or methacrylate or a combination thereof, and the term "(meth)acrylic acid" refers to acrylic acid or methacrylic acid or a combination thereof. As used herein, the term "substituted" refers to having at least one attached chemical group, such as alkyl groups, alkenyl groups, vinyl groups, hydroxyl groups, carboxylic acid groups, other functional groups and combinations thereof.

[0016] As used herein, the term "acrylic polymer" refers to a polymer in which more than 50% by weight of the structural units constituting the polymer contain (meth)acrylic acid monomers or (meth)acrylic acid ester monomers. Preferably, at least 60% by weight of the structural units of the acrylic polymer are (meth)acrylic acid monomers or (meth)acrylic acid ester monomers. More preferably, at least 70% by weight of the structural units of the acrylic polymer are (meth)acrylic acid monomers or (meth)acrylic acid ester monomers. Even more preferably, at least 80% by weight of the structural units of the acrylic polymer are (meth)acrylic acid monomers or (meth)acrylic acid ester monomers. Still more preferably, at least 90% by weight of the structural units of the acrylic polymer are (meth)acrylic acid monomers or (meth)acrylic acid ester monomers.

[0017] As used herein, the term "organophosphorus" refers to an organic compound containing phosphorus. As used herein, the term "phosphate" refers to an anion composed of a phosphorus atom and an oxygen atom. -3 ), polyphosphate (P n O 3n+1 -(n+2) , wherein n is 2 or greater) and metaphosphate (having the formula P m O 3m -m As used herein, "alkaline phosphate" refers to a salt of an alkali metal cation and a phosphate anion. Alkaline phosphates include alkali metal orthophosphates, alkali metal polyphosphates, and alkali metal metaphosphates. Alkaline phosphates also include partially neutralized salts of phosphoric acid, including, for example, partially neutralized salts of orthophosphoric acid, such as, for example, sodium dihydrogen phosphate and disodium hydrogen phosphate.

[0018] As used herein, the term "multi-stage polymer" refers to a polymer prepared by forming (i.e., polymerizing) a first polymer referred to as a "first stage" or "first stage polymer", and then forming a second polymer (which may be an intermediate stage or a final stage) referred to as a "second stage" or "second stage polymer" on or around the first stage in the presence of the first stage. A multi-stage polymer has at least a first stage and a final stage, and optional intermediate stages formed between the first stage and the final stage. Each intermediate stage is formed in the presence of a polymer resulting from the polymerization of the stage immediately preceding the intermediate stage. In such embodiments in which each subsequent stage forms a partial or complete shell around each of the particles remaining from the previous stage, the resulting multi-stage polymer is referred to as a "core / shell" polymer, in which the first stage polymer constitutes the core, and each subsequent stage constitutes a shell on the previous stage, with the final stage forming the outermost shell.

[0019] As used herein, the term "glass transition temperature" or "T g" refers to the temperature at or above which a glassy polymer will undergo segmental motion of the polymer chain. The glass transition temperature of a copolymer can be estimated by the Fox equation (Bulletin of the American Physical Society, 1(3) Page 123 (1956)) as follows:

[0020] 1 / T g =w1 / T g(1) +w2 / T g(2)

[0021] For copolymers, w1 and w2 refer to the weight fractions of the two comonomers, and T g(1) and T g(2) refers to the glass transition temperature of two corresponding homopolymers prepared from these monomers. For polymers containing three or more monomers, an additional term (w n / T g(n) The glass transition temperature of a homopolymer can be found, for example, in "Polymer Handbook", edited by J. Brandrup and EH Immergut, Interscience Publishers. g It can also be measured by various techniques including, for example, differential scanning calorimetry ("DSC"). As used herein, the phrase "calculated T g ” shall mean the glass transition temperature calculated by the Fox equation. When measuring the T of a multistage polymer g When more than one T g The T observed for one stage of a multistage polymer g It can be combined with the T specific to the polymer forming this stage. g (i.e., if the polymer forming this phase were formed and measured separately from the other phases, the observed T g ) are the same. When a monomer has a specific T g When T g .

[0022] As used herein, when it is stated that "the polymer composition contains little or no" a certain substance, it means that the polymer composition does not contain the substance, or if any of the substances are present in the composition of the present invention, the amount of the substance is 1% by weight or less based on the weight of the polymer composition. In embodiments described herein as having "little or no" a certain substance, embodiments in which the certain substance is absent are contemplated.

[0023] Polymer compositions of the present invention contain multi-stage acrylic polymers prepared by aqueous emulsion polymerization. In aqueous emulsion polymerization, water forms a continuous medium in which polymerization occurs. The water may or may not be mixed with one or more additional compounds that are miscible with or soluble in water. Based on the weight of the continuous medium, the continuous medium may contain 30% by weight or more of water, or 50% by weight or more of water, or 75% by weight or more of water, or 90% by weight or more of water.

[0024] Emulsion polymerization involves the presence of one or more initiators. An initiator is a compound that forms one or more free radicals that can initiate the polymerization process. Initiators are typically water soluble. Some suitable initiators form one or more free radicals when heated. Some suitable initiators are oxidizing agents and form one or more free radicals when mixed with one or more reducing agents, or when heated, or a combination thereof. Some suitable initiators form one or more free radicals when exposed to radiation (such as, for example, ultraviolet radiation or electron beam radiation). Combinations of suitable initiators are also suitable.

[0025] Preferably, the multi-stage acrylic polymer is prepared by emulsion polymerization to form a latex. The latex preferably has an average particle size of, for example, 50 nm or more, or 100 nm or more. The latex preferably has an average particle size of, for example, less than 1 micron, or less than 800 nm, or less than 600 nm.

[0026] Emulsion polymerization can optionally use at least one organic phosphorus soap containing anionic phosphate surfactant. Each anionic phosphate surfactant has a cation associated therewith to form an alkali metal salt of a phosphate surfactant, including, for example, alkyl phosphates and alkyl aryl phosphates. Suitable cations include, for example, ammonium, alkali metal cations and mixtures thereof. Suitable alkali metal salts of phosphate surfactants include, for example, polyoxyalkylene alkylphenyl ether phosphates, polyoxyalkylene alkyl ether phosphates, polyoxyethylene alkylphenyl ether phosphates and polyoxyethylene alkyl ether phosphates. The alkali metal salt of a phosphate surfactant can include polyoxyethylene alkyl ether phosphates. The weight of the phosphate surfactant present in the emulsion polymerization of the multistage polymer can be in the range of, for example, 0.5 wt % or more, preferably 1.0 wt % or more, and more preferably 1.5 wt % or more, as characterized by the weight of the phosphate surfactant based on the total monomer weight added to the polymerization. When present in the emulsion polymerization of the multi-stage acrylic polymer, the weight of the phosphate surfactant can be in the range of, for example, 5 wt % or less, preferably 4 wt % or less, and more preferably 3 wt % or less, as characterized by the weight of the phosphate surfactant based on the total monomer weight added to the polymerization. One or more anionic surfactants other than the anionic phosphate surfactants described above can also be used in the emulsion polymerization. Suitable additional anionic surfactants include, for example, carboxylates, sulfosuccinates, sulfonates, and sulfates.

[0027] The multi-stage acrylic polymer of the present invention contains a first-stage acrylic polymer containing structural units of at least one organophosphorus monomer. As used herein, the term "organophosphorus monomer" refers to a phosphorus-containing monomer. The organophosphorus monomer can be in the acid form or in the form of a salt of a phosphoric acid group. Examples of organophosphorus monomers include:

[0028]

[0029] Wherein R is an organic group containing an acryloyloxy, methacryloyloxy or vinyl group, and R' and R" are independently selected from H and a second organic group. The second organic group can be saturated or unsaturated. Suitable organophosphorus monomers include dihydrogen phosphate functional monomers, such as dihydrogen phosphate esters of alcohols, wherein the alcohol also contains a polymerizable vinyl or alkenyl group, such as allyl phosphate, monophosphate or diphosphate of bis(hydroxy-methyl)fumaric acid or itaconic acid, derivatives of (meth)acrylates, such as, for example, phosphate esters of hydroxyalkyl (meth)acrylates (including 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, etc.).

[0030] Other suitable organophosphorus monomers include CH2═C(R)—C(O)—O—(R'O)n - P(O)(OH)2, where R = H or -CH3, R' = alkyl, and n = 1 to 5, such as the methacrylate SIPOMER available from Solvay TM PAM-100, SIPOMER TM PAM-200, SIPOMER TM PAM-400, SIPOMER TM PAM-600 and Acrylate SIPOMER TM PAM-300.

[0031] Other suitable organophosphorus monomers are phosphonate functional monomers disclosed in WO 99 / 25780A1 and include vinylphosphonic acid, allylphosphonic acid, 2-acrylamido-2-methylpropanephosphonic acid, α-phosphonostyrene, 2-methacrylamido-2-methylpropanephosphonic acid. Further suitable organophosphorus monomers are 1,2-ethylenically unsaturated (hydroxy)phosphinylalkyl (meth)acrylate monomers disclosed in U.S. Pat. No. 4,733,005 and include (hydroxy)phosphinyl methyl methacrylate.

[0032] Preferably, the organic phosphorus monomer comprises at least one compound of the formula CH2═C(R)—C(O)—O—(R'O) n More preferably, R is -CH3, R' is an alkyl group including 1 to 6 carbon atoms, and n=1.

[0033] The first stage may contain structural units of at least one organophosphorus monomer in an amount of 0.25 wt % or more, or 0.5 wt % or more, based on the total weight of the first stage acrylic polymer. The first stage may contain polymerized units derived from at least one organophosphorus monomer in an amount of 5 wt % or less, 4 wt % or less, 3 wt % or less, 2.5 wt % or less, or 2.0 wt % or less, based on the total weight of the first stage acrylic polymer. Preferably, the first stage contains structural units of at least one organophosphorus monomer in an amount ranging from 0.25 wt % to less than 5 wt %, based on the total weight of the first stage polymer. More preferably, the first stage contains structural units of at least one organophosphorus monomer in an amount ranging from 0.5 wt % to 3 wt %, based on the total weight of the first stage.

[0034] The first stage acrylic polymer also comprises structural units of one or more substituted or unsubstituted (meth)acrylate monomers. Preferably, the first stage polymer comprises structural units of one or more alkyl (meth)acrylate monomers, wherein the alkyl group of the alkyl (meth)acrylate monomer is selected from linear alkyl groups and branched alkyl groups having 1 to 12 carbon atoms. More preferably, the first stage comprises structural units of at least one monomer selected from butyl acrylate, ethylhexyl acrylate (e.g., 2-ethylhexyl acrylate), ethyl acrylate, methyl methacrylate, butyl methacrylate, and isooctyl acrylate. Even more preferably, the first stage comprises structural units of at least one monomer selected from butyl acrylate and ethylhexyl acrylate.

[0035] The first stage acrylic polymer may be polymerized in the presence of a cross-linking or grafting monomer. Examples of cross-linking and / or grafting monomers that can be used for the first stage acrylic polymer include, but are not limited to, butylene glycol diacrylate, butylene glycol dimethacrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, divinylbenzene, diethylene glycol diacrylate, diethylene glycol dimethacrylate, diallyl maleate, allyl methacrylate, diallyl phthalate, triallyl phthalate, trimethylolpropane triacrylate. Preferably, the first stage acrylic polymer contains structural units of allyl methacrylate. When present, the first stage polymer may contain structural units of the cross-linking or grafting monomer in an amount of 0.1 wt % to 10 wt % based on the total weight of the first stage acrylic polymer. Preferably, the first stage polymer contains structural units of the cross-linking or grafting monomer in an amount of 0.2 wt % to 5 wt % based on the total weight of the first stage acrylic polymer.

[0036] Preferably, the first stage polymer has a T of 40°C or less, 20°C or less, 0°C or less, -20°C or less, or -35°C or less, or -50°C or less. g The first-stage polymer preferably has a T of -150°C or higher, or -100°C or higher. g .

[0037] The multistage polymer may contain, for example, 70 wt% or more, or 80 wt% or more, or 90 wt% or more of the first stage polymer, based on the total weight of the multistage polymer. The multistage polymer may contain 98 wt% or less, or 95 wt% or less of the first stage polymer, based on the total weight of the multistage polymer.

[0038] The final stage is formed on or around the first stage acrylic polymer, either directly on or around the first stage acrylic polymer, or indirectly by forming the final stage on an intermediate stage. Preferably, the final stage acrylic polymer is grafted to the first stage acrylic polymer via a graft linker used to form the first stage acrylic polymer.

[0039] The final stage acrylic polymer preferably comprises structural units of one or more aryl (meth)acrylate or alkyl (meth)acrylate monomers, wherein the alkyl group of the alkyl (meth)acrylate monomer is selected from linear alkyl groups and branched alkyl groups having 1 to 12 carbon atoms. Preferably, the final stage acrylic polymer comprises structural units of one or more monomers selected from butyl acrylate, ethylhexyl acrylate, ethyl acrylate, methyl methacrylate, butyl methacrylate, cyclohexyl (meth)acrylate, cyclopentyl methacrylate, tetrahydrofuranyl methacrylate and benzyl (meth)acrylate. More preferably, the final stage acrylic polymer comprises structural units of methyl methacrylate.

[0040] The final stage acrylic polymer may also contain structural units of one or more substituted or unsubstituted styrenes. Suitable substituted styrenes include, for example, α-alkyl styrenes (e.g., α-methyl styrene). When present, structural units of one or more substituted or unsubstituted styrenes may account for up to 40% by weight of the total weight of the final stage acrylic polymer. For example, structural units of one or more substituted or unsubstituted styrenes may account for 5%, 10%, 20%, 30%, or 40% by weight of the total weight of the final stage acrylic polymer.

[0041] The final stage polymer may have a T of 50°C or higher, or 90°C or higher. g The final stage polymer may have a T of 200°C or less, or 150°C or less. g .

[0042] The multistage polymer may contain, for example, 2 wt% or more, or 5 wt% or more, or 8 wt% or more of the final-stage polymer, based on the total weight of the multistage polymer. The multistage polymer may contain, for example, 30 wt% or less, or 20 wt% or less, or 15 wt% or less of the final-stage polymer, based on the total weight of the multistage polymer.

[0043] The multi-stage polymer may contain one or more intermediate stage polymers. Based on the total weight of the multi-stage polymer, the total amount of the intermediate stage polymer may be present in an amount of 1 wt % or more, or 2 wt % or more, or 5 wt % or more, or 10 wt % or more. Based on the total weight of the multi-stage polymer, the total amount of the intermediate stage polymer may be present in an amount of 60 wt % or less, or 2 wt % or less, or 5 wt % or less, or 10 wt % or less. Like the first stage acrylic polymer in the multi-stage polymer, one or more intermediate stage polymers may also contain polymerization units derived from one or more organophosphorus monomers. One or more intermediate stage acrylic polymers may contain structural units of one or more monomers selected from (meth) aryl acrylate monomers and (meth) alkyl acrylate monomers, wherein the alkyl group of the (meth) alkyl acrylate monomer is selected from a linear alkyl group and a branched alkyl group having 1 to 12 carbon atoms.

[0044] In the method of the present invention, the multi-stage polymer latex can be separated by coagulation or spray drying to form a powder. Preferably, the multi-stage polymer latex is separated by coagulation.

[0045] When present, the organophosphorus soap may be retained on the surface of the multi-stage polymer upon coagulation. Suitable coagulation methods include, for example, coagulation with divalent cations.

[0046] Suitable divalent cations include, for example, divalent metal cations and alkaline earth metal cations. Suitable divalent cations include, for example, calcium (+2), cobalt (+2), copper (+2), iron (+2), magnesium (+2), zinc (+2) and mixtures thereof. Preferably, the multivalent cation is selected from calcium (+2) and magnesium (+2). More preferably, each divalent cation present is calcium (+2) or magnesium (+2) or mixtures thereof. Even more preferably, the divalent cation includes calcium (+2). Based on the dry weight of the multistage polymer, the divalent cation may be present, for example, in an amount of 10ppm or more, or 30ppm or more, or 100ppm or more by weight. Based on the dry weight of the multistage polymer, the divalent cation may be present, for example, in an amount of 3% by weight or less, or 1% by weight or less, or 0.3% by weight or less.

[0047] Preferably, most or all of the divalent cations present in the composition are in the form of water-insoluble phosphates. The molar amount of divalent cations present in the form of water-insoluble phosphates can be, for example, 80% or more, or 90% or more, or 95% or more, or 98% or more, or 100%, based on the total moles of divalent cations present in the composition.

[0048] Preferably, most or all of the water retained with the separated polymer is removed from the separated polymer by one or more of the following operations: filtration (including, for example, vacuum filtration) and / or centrifugation. The separated polymer may optionally be washed with water one or more times. The coagulated polymer is a complex structure, and it is known that water cannot easily contact every part of the coagulated polymer. Although it is not desired to be bound by theory, it is considered that a significant amount of divalent cations and residual organophosphorus soaps will be left. Therefore, based on the dry weight of the multistage polymer, the composition of the present invention may contain an organophosphorus soap in an amount of 50ppm or more, or 100ppm or more, or 500ppm or more. Based on the dry weight of the multistage polymer, the composition of the present invention may contain an organophosphorus soap in an amount of 10,000ppm or less, or 7,500ppm or less, or 5,000ppm or less.

[0049] Preferably, the dried multi-stage polymer has a water content of less than 1.0 wt. % based on the weight of the dried multi-stage polymer.

[0050] Polymer composition of the present invention can also include stabilizer. Suitable stabilizer includes for example free radical scavenger, peroxide decomposer and metal deactivator. Suitable free radical scavenger includes for example hindered phenol (for example, those hindered phenols with tertiary butyl groups connected to each carbon atom of aromatic ring adjacent to the carbon atom connected to hydroxyl group), secondary aromatic amine, hindered amine, hydroxylamine and benzofuranone. Suitable peroxide decomposer includes for example organic sulfide (for example, divalent sulfur compound, for example ester of thiodipropionic acid), ester and hydroxylamine of phosphorous acid (H3PO3). Suitable metal deactivator includes for example chelating agent (for example, ethylenediaminetetraacetic acid).

[0051] As described above, one aspect of the present invention utilizes the polymer composition described herein as an impact modifier in a matrix resin composition containing a multi-stage polymer composition and a matrix resin. After the mixture of the multi-stage acrylic polymer powder and the matrix resin is mixed and melted and formed into a solid article, the impact resistance of the article will be better than the same solid article made of the matrix resin that is not mixed with the multi-stage polymer. The multi-stage polymer can be provided in a solid form (e.g., pellets or powders or mixtures thereof). The matrix resin can also be provided in a solid form (e.g., pellets or powders or mixtures thereof). The solid multi-stage acrylic polymer powder can be mixed with the solid matrix resin at room temperature (20°C) or an elevated temperature (e.g., 30°C to 90°C). Alternatively, the solid multi-stage acrylic polymer powder can be mixed with a molten matrix resin, such as in an extruder or other melt mixer. The solid multi-stage acrylic polymer powder can also be mixed with a solid matrix resin, and then the solid mixture can be heated sufficiently to melt the matrix resin, and the mixture can be further mixed, for example, in an extruder or other melt processing device.

[0052] The weight ratio of matrix resin to the multi-stage acrylic polymer powder of the present invention can range, for example, from 1:1 or more, or 1.1:1 or more, or 2.3:1 or more, or 4:1 or more, or 9:1 or more, or 19:1 or more, or 49:1 or more, or 99:1 or more.

[0053] Suitable matrix resins include, for example, polyolefins, polystyrenes, styrene copolymers, polyvinyl chloride, poly(vinyl acetate), acrylic polymers, polyethers, polyesters, polycarbonates, polyurethanes, and polyamides. Preferably, the matrix resin contains at least one polycarbonate. Suitable polycarbonates include, for example, homopolymers of polymerized units derived from bisphenol A ("BPA"), and copolymers comprising polymerized units of BPA and one or more other polymerized units.

[0054] The matrix resin may contain at least one polyester. Suitable polyesters include, for example, polyethylene terephthalate and polybutylene terephthalate.

[0055] The matrix resin may contain a blend of polymers. Suitable polymer blends include, for example, blends of polycarbonate and styrene resins, and blends of polycarbonate and polyesters. Suitable styrene resins include, for example, polystyrene and copolymers of styrene with other monomers, such as acrylonitrile / butadiene / styrene ("ABS") resins.

[0056] The matrix resin composition containing multi-stage acrylic polymer and matrix resin can contain one or more other materials added to the mixture. Before forming the final mixture of all materials, any one or more of such other materials can be added to the multi-stage polymer or the matrix resin. When the matrix resin is in solid form or molten form, each material (if used) in the other material can be added (alone or in combination with each other and / or in combination with the multi-stage polymer) to the matrix resin. Suitable other materials include, for example, dyes, colorants, pigments, carbon black, fillers, fibers, lubricants (for example, montan wax), flame retardants (for example, borates, antimony trioxide or molybdates) and other impact modifiers that are not multi-stage polymers of the present invention.

[0057] The matrix resin composition can be used to form useful articles, for example, by film blowing, profile extrusion, molding, other methods, or combinations thereof. Molding methods include, for example, blow molding, injection molding, compression molding, other molding methods, and combinations thereof.

[0058] The multi-stage polymers of the present invention can provide significant improvements in the flammability of the matrix resin composition.

[0059] Some embodiments of the present invention will now be described in detail in the following examples.

[0060] Example

[0061] Preparation of multi-stage acrylic acid polymers

[0062] 1873g of deionized water, 1.5g of tetrasodium pyrophosphate and 0.2g of alkyl diphenyl oxide disulfonate were added to a 5-liter 4-necked round-bottom flask equipped with a mechanical stirrer, a thermometer, a condenser and an electric heating mantle. The reactor contents were purged with nitrogen and heated to 45°C under stirring. In a separate container, 91g of butyl acrylate, 30g of 2-ethylhexyl acrylate and 1g of allyl methacrylate were mixed. The monomer mixture was then added to the kettle as a single shot. 0.3g of tert-butyl hydroperoxide and 0.25g of sodium formaldehyde sulfoxylate were then added immediately. The reaction contents were maintained until the reaction exotherm was complete, after which the reaction contents were brought to 50°C and a mixture consisting of 91g of butyl acrylate, 30g of 2-ethylhexyl acrylate and 1g of allyl methacrylate was added, followed by 0.1g of tert-butyl hydroperoxide and 0.1g of sodium formaldehyde sulfoxylate. The reaction contents were maintained until the reaction exotherm was complete, then 2.0 g of alkyl diphenyl oxide disulfonate was added to the reactor, after which the reaction contents were allowed to reach 50° C. again. A mixture consisting of 327 g of butyl acrylate, 109 g of 2-ethylhexyl acrylate, and 3 g of allyl methacrylate was then added, followed by 0.3 g of tert-butyl hydroperoxide and 0.3 g of sodium formaldehyde sulfoxylate. The reaction contents were maintained until the reaction exotherm was complete, then 4.0 g of alkyl diphenyl oxide disulfonate was added to the reactor, and the reaction contents were allowed to reach 50° C. again. A mixture consisting of 327 g of butyl acrylate, 109 g of 2-ethylhexyl acrylate, and 3 g of allyl methacrylate was then added, followed by 0.3 g of tert-butyl hydroperoxide and 0.3 g of sodium formaldehyde sulfoxylate. The reaction contents were held until the reaction exotherm was complete, then a redox couple consisting of 0.1 g t-butyl hydroperoxide and 0.1 g sodium formaldehyde sulfoxylate was added, followed by 1.3 g alkyl diphenyl oxide disulfonate and held for a duration of 20 minutes. The reaction contents were allowed to reach 50°C again, then 97 g methyl methacrylate was added to the reactor, followed by 0.3 g t-butyl hydroperoxide and 0.3 g sodium formaldehyde sulfoxylate. After the exotherm was complete, the reaction contents were held for 10 minutes. After the hold, the batch was cooled to 40°C and then packaged when the emulsion was characterized and found to have a particle size of 308 nm and 34.9% solids.

[0063] For adding phosphate monomer (SIPOMER TM PAM-600 (phosphoethyl methacrylate), using half the feed in each of the 3rd and 4th monomer mixture additions, and replacing the alkyl diphenyl oxide disulfonate with an organophosphorus soap on an active basis.

[0064] A control sample (Comparative Example 1) and samples of the invention (Examples 1 and 2) were prepared using compositions according to Table 1 below, where the values ​​are provided as weight % of the monomers in the first stage acrylic polymer.

[0065] Multi-stage acrylic polymer coagulation

[0066] Preparation of antioxidant emulsion

[0067] Into a 250 ml plastic container was added 1.5 g Dowfax 2A1 (25%), 12.7 g Irganox 1076 and 70.9 g deionized water. The mixture was heated to 60°C and homogenized at 10,000 rpm for 5 minutes.

[0068] Emulsion preparation

[0069] To a 1 liter bottle was added 481.6 g of emulsion (CP7605-"Comparative Example 1", EXL-2390 control) diluted to 30% TS with 85.1 g of deionized water and heated to 51° C. in a water bath. Once the target temperature was reached, 34.2 g of the antioxidant emulsion listed above was added and mixed thoroughly. The emulsion was stored at 51° C. until ready to coagulate.

[0070] Condensation

[0071] 4.76g of calcium chloride powder and 1133.3g of deionized water were added to a 3-liter beaker. The contents of the beaker were heated to 51°C with stirring at 350rpm. When the contents reached 51°C, the preheated emulsion was slowly added to the beaker in 45 to 60 seconds. This resulted in the mixture being separated into an aqueous phase and a solid polymer phase. 79.3g of a 10% calcium chloride aqueous solution was added to complete coagulation. One minute later, 30.6g of K-120 (diluted to 10% TS) was slowly added to the beaker. The mixture was then heated to 81°C and maintained at 81°C for 30 minutes. After maintenance, the mixture was cooled, dehydrated, and washed in a Buchner funnel. The sample was washed with deionized water until the filtrate conductivity was less than 30μS / m, and then dehydrated. After dehydration, the resulting wet cake was treated with a phosphate spray. The phosphate spray consisted of 0.9 g of a 6% sodium dihydrogen phosphate solution and 7.43 g of a 20% disodium phosphate solution. The sample was dried in a vacuum oven at 65°C overnight. The particle size of the powder was measured on a Malvern Mastersizer 2000.

[0072] In other embodiments, the above methods are modified to incorporate the addition of additional components.

[0073] Table 1

[0074]

[0075] Comparative Example 2

[0076] Preparation of Comparative Polymer Composition M732

[0077] The multi-stage acrylic polymer powder of the present invention was compared with a commercially available impact modifier having flame retardant properties (product name M-732 manufactured by Kaneka Corporation). The rubber component of M-732 is polybutadiene and is a core / shell type methacrylate-butadiene-styrene copolymer.

[0078] Polycarbonate formulations

[0079] Polycarbonate formulations were prepared with the multi-stage acrylic polymer powders (AIM) of Comparative Example 1 and Examples 1 and 2 and the M-732 powder (MBS) of Comparative Example 2. The formulations according to Table 1 were compounded in an extruder to produce pellets for injection molding.

[0080] Table 2

[0081]

[0082] PC Lexan 141: Polycarbonate from SABIC

[0083] AIM / MBS: AIM powder of Examples 1 and 2 and Comparative Example 1 or M-732 powder of Comparative Example 2

[0084] FR-2025a: 100% potassium perfluorobutane sulfonate from 3M 1076 and 168: Antioxidants from BASF

[0085] The polycarbonate formulations were injection molded to form double-ended gated 1.5 mm ASTM burn bars for flammability testing using the UL 94 flammability test method. The injection molding conditions are shown in Table 3 below.

[0086] Table 3

[0087]

[0088] The results of the UL 94 test are shown in the graph of FIG1 , which shows the total burn time of the five bars after ignition. As can be seen from the graph in FIG1 , the multi-stage acrylic powder formulations of Examples 1 and 2 performed well in the UL 94 test, with each sample scoring a V-1 rating or better. Example 2 scored a V-0 rating for flammability in the UL 94 test, which is an improvement over Comparative Example 1, and had significantly better t2 and t1+t2 burn times than Comparative Example 2.

[0089] The Izod notched impact results are shown in Table 4 below. As shown in Table 4, the impact strength of the inventive example shows improvement over that of Comparative Example 2.

[0090] Table 4

[0091]

Claims

1. A multi-stage acrylic acid composition, comprising: (a) a first-stage acrylic polymer, wherein the first-stage acrylic polymer comprises structural units of at least one organophosphorus monomer, and (b) a final stage acrylic polymer formed on or around the first stage acrylic polymer; The multi-stage acrylic composition is in powder form.

2. The composition according to claim 1, wherein the first-stage polymer further comprises structural units of one or more alkyl (meth)acrylate monomers, wherein the alkyl group of the alkyl (meth)acrylate monomer is selected from a linear alkyl group and a branched alkyl group having 1 to 12 carbon atoms.

3. The composition of claim 2, wherein the first stage polymer comprises structural units of at least one monomer selected from the group consisting of butyl acrylate, ethylhexyl acrylate, ethyl acrylate, methyl methacrylate, butyl methacrylate, and isooctyl acrylate.

4. The composition according to any of the preceding claims, wherein the first stage polymer further comprises structural units of at least one monomer selected from the group consisting of butanediol diacrylate, butanediol dimethacrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, divinylbenzene, diethylene glycol diacrylate, diethylene glycol dimethacrylate, diallyl maleate, allyl methacrylate, diallyl phthalate, triallyl phthalate, trimethylolpropane triacrylate.

5. A composition according to any one of the preceding claims, wherein the at least one organophosphorus monomer is of the formula CH2═C(R)—C(O)—O—(R′O) n —P(O)(OH)2 compounds, wherein R is H or —CH3, R′ is an alkyl group, and n is in the range of 1 to 5.

6. The composition of claim 5, wherein R is -CH3 and R' is an alkyl group containing 1 to 6 carbon atoms.

7. The composition of any one of the preceding claims, wherein the final stage acrylic polymer comprises structural units of one or more aryl (meth)acrylate or alkyl (meth)acrylate monomers, wherein the alkyl group of the alkyl (meth)acrylate monomer is selected from linear alkyl groups and branched alkyl groups having 1 to 12 carbon atoms.

8. The composition of claim 7, wherein the final stage acrylic polymer comprises structural units of one or more monomers selected from the group consisting of butyl acrylate, ethylhexyl acrylate, ethyl acrylate, methyl methacrylate, butyl methacrylate, cyclohexyl (meth)acrylate, cyclopentyl methacrylate, tetrahydrofuranyl methacrylate, and benzyl (meth)acrylate.

9. The composition of any of the preceding claims, wherein the first stage polymer is present in an amount of 70 to 98 weight percent, based on the total weight of the multi-stage polymer, and the final stage polymer is present in an amount of 2 to 30 weight percent, based on the total weight of the multi-stage polymer.

10. The composition of any one of the preceding claims, wherein the at least one organophosphorus monomer is present in the first-stage polymer in an amount of less than 5 weight percent, based on the total weight of the first-stage polymer.

11. The composition of claim 10, wherein the at least one organophosphorus monomer is present in the first-stage acrylic polymer in an amount of less than 3 weight percent, based on the total weight of the first-stage acrylic polymer.

12. The composition of any one of the preceding claims, further comprising at least one organophosphorus soap in an amount of 50 ppm or more based on the dry weight of the multi-stage polymer.

13. The composition according to claim 12, wherein the organophosphorus soap comprises one or more of polyoxyalkylene alkylphenyl ether phosphate salts, polyoxyalkylene alkyl ether phosphate salts, polyoxyethylene alkylphenyl ether phosphate salts, and polyoxyethylene alkyl ether phosphate salts.

14. A matrix resin composition comprising mixing one or more matrix resins with a composition according to any one of the preceding claims.

15. The matrix resin composition of claim 14, wherein the matrix resin is selected from the group consisting of one or more polycarbonates, one or more polycarbonates blended with one or more polyesters, and one or more polycarbonates blended with one or more ABS resins.

Images