Allyl-functional thermoplastic additives for thermosetting polymers.

Abstract

Disclosed is a branched polymer that is the reaction product of reactants including one or more monoethylenically unsaturated ester monomers, a chain transfer agent in an amount of 0.1 to 15 weight percent, and a crosslinker in an amount of 0.1 to 15 weight percent, the weight percent being based on the total amount of reactants, with the proviso that the amount of crosslinker is within ±5 weight percent of the amount of chain transfer agent, and the crosslinker contains at least two carbon-carbon double bonds having different reactivities. Also disclosed is a thermosetting composition prepared by crosslinking the branched polymer and the acrylic polymer.

Description

[Technical Field]

[0001] The field of this invention is branched polymer additives and thermosetting compositions made from such additives. [Background technology]

[0002] Branched acrylic polymers have been proposed. For example, Isaure et al., J. Mater. Chem., 2003, 13, 2701-2710, discloses branched copolymers containing methyl methacrylate (MMA), a chain transfer agent (CTA), and ethylene glycol dimethacrylate (EGDMA). In these branched acrylic copolymers, Isaure found that up to 4.5% of the pendant double bonds from EGDMA remained unreacted. Summary of the Invention

[0003] Disclosed herein is a composition comprising a branched polymer that is the reaction product of reactants comprising one or more monoethylenically unsaturated ester monomers, a chain transfer agent in an amount of 0.1 to 15 weight percent, and a crosslinker in an amount of 0.1 to 15 weight percent, the weight percent being based on the total amount of reactants, with the proviso that the amount of crosslinker is within ±5 weight percent of the amount of chain transfer agent, and the crosslinker comprises at least two carbon-carbon double bonds of different reactivity. The branched polymer is not crosslinked.

[0004] Also disclosed herein are thermosetting polymers comprising the above compositions. [Brief explanation of the drawings]

[0005] [Figure 1] The figure shows DMA G' overlays of plaques with and without high temperature thermal organic peroxide. DETAILED DESCRIPTION OF THE INVENTION

[0006] Disclosed herein are branched polymers comprising a crosslinker having at least two carbon-carbon double bonds of different reactivity. The inventors have surprisingly found that branched polymers comprising a crosslinker having at least two carbon-carbon double bonds of different reactivity can produce branched acrylic polymers in which at least 80% of the pendant double bonds remain unreacted.

[0007] Also disclosed is a thermosetting composition comprising a branched polymer and an acrylic polymer. Applicants have surprisingly found that the branched polymers of the present invention can improve the high temperature properties of acrylic polymers.

[0008] The branched polymer is a reaction product of reactants including one or more monoethylenically unsaturated ester monomers, a chain transfer agent in an amount of 0.1 to 15 weight percent, and a crosslinker in an amount of 0.1 to 15 weight percent, the weight percent being based on the total amount of reactants.

[0009] The crosslinker is a polyfunctional unsaturated monomer containing at least two carbon-carbon double bonds with different reactivities. Preferably, the crosslinker is selected from allyl methacrylate, allyl acrylate, and combinations thereof. In allyl (meth)acrylate, the allyl group has a different reactivity from the vinyl group. Conventional crosslinkers, such as di(meth)acrylate, have carbon-carbon double bonds with the same reactivity. Using NMR spectroscopy, the inventors have found that pendant double bonds using crosslinkers with the same reactivity react almost completely during polymerization to form branch points. The crosslinker according to the present invention remains substantially unreacted, for example, at least 80% of the pendant double bonds remain unreacted after polymerization. These unreacted pendant double bonds provide additional opportunities for further grafting.

[0010] Preferably, the crosslinking agent is present in an amount of at least 0.5 weight percent, at least 1 weight percent, at least 2 weight percent, or at least 3 weight percent. Preferably, the crosslinking agent is present in an amount of no more than 14 weight percent, no more than 13 weight percent, no more than 12 weight percent, no more than 11 weight percent, or no more than 10 weight percent.

[0011] The branched polymer is not crosslinked. To avoid crosslinking, the amount of crosslinker is within ±5 weight percent of the amount of chain transfer agent. Preferably, the amount of crosslinker is within ±4 weight percent of the amount of chain transfer agent. More preferably, the amount of crosslinker is within ±3 weight percent of the amount of chain transfer agent.

[0012] Surprisingly, the inventors have found that the amount of crosslinking agent can exceed the amount of chain transfer agent while still forming a branched polymer. Crosslinking agents with functional groups having similar activity will form a crosslinked polymer if the amount of crosslinking agent in molar units exceeds the amount of chain transfer agent in molar units. According to the present invention, the amount of crosslinking agent in molar units can exceed the amount of chain transfer agent without forming a crosslinked polymer.

[0013] Suitable monoethylenically unsaturated ester monomers useful for making branched polymers according to certain embodiments can have the structure R'-C(O)OR, where R is a hydrocarbyl group (e.g., an alkyl group or an aryl group) and R' is a monoethylenically unsaturated aliphatic group having at least 2 or 3 carbon atoms. Preferably, R is an alkyl group of at least 1, 2, or 3 carbon atoms. According to certain embodiments, R is an alkyl group having 12, 10, 8, 6, or 5 or fewer carbon atoms. According to certain embodiments, R is an aryl group of 6 to 12 carbon atoms. According to certain embodiments, R' has 6 or fewer carbon atoms. Examples of suitable monomers include methyl acrylate, butyl acrylate, ethylhexyl acrylate, ethyl acrylate, methyl methacrylate, butyl methacrylate, cyclohexyl (meth)acrylate, cyclopentyl methacrylate, tetrahydrofurfyl methacrylate, and benzyl (meth)acrylate. A combination of two or more such monoethylenically unsaturated ester monomers can be used. For example, a combination of methyl methacrylate and butyl methacrylate can be used. For example, the amount of methyl methacrylate can be at least 20, 30, 40, 50, 60, 70, or 80 weight percent of the reactants, and can be less than 99.8, 99, 98, 97, 96, 95, 90, or 85 weight percent of the reactants. The second monoethylenically unsaturated ester monomer (e.g., butyl acrylate) can be 0 or more than 0, 1, 2, 3, 4, or 5 weight percent of the reactants, and less than 60, 50, 40, 30, 20, or 10 weight percent of the reactants. In certain embodiments, additional monoethylenically unsaturated ester monomers can be used. In such embodiments, the combination of the second and additional monoethylenically unsaturated monomer(s) taken together is greater than 0, 1, 2, 3, 4, or 5 weight percent of the reactants and less than 60, 50, 40, 30, 20, or 10 of the reactants.

[0014] According to certain embodiments, one or more additional monounsaturated addition-polymerizable (e.g., monoethylenically unsaturated) monomers may be included. For example, styrene or acrylonitrile may be added. The amount of such additional monounsaturated addition-polymerizable monomers is preferably less than 10 or 5 weight percent based on the weight of the reactants.

[0015] Preferably, the monoethylenically unsaturated ester monomer is present in the branching monomer in an amount of at least 65 weight percent, e.g., at least 70 weight percent, at least 75 weight percent, at least 80 weight percent, at least 85 weight percent, or at least 90 weight percent, etc., based on the total weight of the reactants forming the branching monomer.

[0016] The reactants further include a chain transfer agent (CTA). The chain transfer agent can be any compound known or discovered to be useful as a chain transfer agent in the polymerization of acrylate or methacrylate monomers. For example, a thiol chain transfer agent can be used. Examples of such thiol CTAs include monofunctional and multifunctional thiols. Monofunctional thiols include, but are not limited to, propyl mercaptan, butyl mercaptan, hexyl mercaptan, octyl mercaptan, dodecyl mercaptan, thioglycolic acid, mercaptopropionic acid, alkyl thioglycolates such as 2-ethylhexyl thioglycolate or octyl thioglycolate, mercaptoethanol, mercaptoundecanoic acid, thiolactic acid, and thiobutyric acid. Polyfunctional thiols include trifunctional compounds such as trimethylolpropane tris(3-mercaptopropionate), tetrafunctional compounds such as pentaerythritol tetra(3-mercaptopropionate), pentaerythritol tetrathioglycolate, pentaerythritol tetrathiolactate, and pentaerythritol tetrathiobutyrate, hexafunctional compounds such as dipentaerythritol hexa(3-mercaptopropionate) and dipentaerythritol hexathioglycolate, and octafunctional thiols such as tripentaerythritol octa(3-mercaptopropionate) and tripentaerythritol octathioglycolate. The use of polyfunctional thiols is a useful method for increasing the branching degree of polymers. Optionally, the chain transfer agent can contain a mixture of two or more compounds. Preferably, the CTA is as follows: [ka]

[0017] Preferably, the chain transfer agent is present in an amount of at least 0.5 weight percent, at least 1 weight percent, at least 2 weight percent, or at least 3 weight percent. Preferably, the chain transfer agent is present in an amount of no more than 14 weight percent, no more than 13 weight percent, no more than 12 weight percent, no more than 11 weight percent, or no more than 10 weight percent.

[0018] The alternative chain transfer agent can be any species known to reduce molecular weight in conventional free-radical polymerization of vinyl monomers. Examples include sulfides, disulfides, and halogen-containing species. Catalytic chain transfer agents such as cobalt complexes, e.g., cobalt(II) chelates such as cobalt porphyrin compounds, are also useful chain transfer agents for the present invention. Suitable cobalt chelates are known in the art and are described in WO 98 / 04603. A particularly suitable compound is bis(borondifluorodimethylglyoximate)cobaltate(II), also known as CoBF. Catalytic chain transfer agents are generally very effective at low concentrations and can therefore be used at relatively low concentrations, e.g., <0.5 wt %, preferably <0.1 wt % (based on monofunctional monomer), compared to conventional thiol chain transfer agents. Surprisingly, we have found that catalytic chain transfer compounds based on cobalt complexes can be used very effectively in the polymerization process of the present invention to obtain soluble branched polymers at concentrations of less than 0.05% by weight (500 ppmw), for example 0.0001 to 0.01% by weight (1 to 100 ppmw), based on the monofunctional monomer.

[0019] According to certain embodiments, the crosslinker is allyl methacrylate (ALMA), the chain transfer agent is BMP, and the monoethylenically unsaturated ester monomer is selected from methyl methacrylate (MMA) and butyl methacrylate (BMA). Preferably, MMA or BMA is present in an amount of 80 to 98 weight percent, the amount of BGDMA is in the range of 1 or 10 weight percent, and the amount of ALMA is in the range of 1 to 10 weight percent, based on the total weight of MMA or BMA, BMP, and ALMA.

[0020] The branched polymers can be made using any free radical polymerization method, for example, solution, suspension, emulsion, and bulk polymerization methods can all be used, for example, conventional emulsion polymerization can be used.

[0021] Surfactants or emulsifiers can be used to form the branched polymer. Examples of emulsifiers include nonionic, anionic, and cationic emulsifiers.

[0022] Suitable nonionic emulsifiers are araliphatic or aliphatic nonionic emulsifiers, examples of which include ethoxylated mono-, di-, and trialkylphenols (degree of ethoxylation: 3 to 50, alkyl radical: C4-C6). 10 ), ethoxylate of long-chain alcohol (ethoxylation degree: 3-100, alkyl radical: C8-C 36 ), and polyethylene oxide / polypropylene oxide homopolymers and copolymers. These may contain alkylene oxide units copolymerized in random distribution or in the form of blocks. For example, ethylene oxide / propylene oxide block copolymers are very suitable. Ethoxylates of long-chain alkanols (alkyl radicals C1-C 30 It is preferable to use linear C 12 -C 20 Those with alkyl radicals and an average degree of ethoxylation of 10 to 50, as well as ethoxylated monoalkylphenols, are also particularly preferred.

[0023] Suitable anionic emulsifiers are, for example, alkyl sulfates (alkyl radical: C-C 22 ), ethoxylated alkanol (ethoxylation degree: 2 to 50, alkyl radical: C 12 -C 18) and ethoxylated alkylphenols (ethoxylation degree: 3-50, alkyl radical: C4-C9), sulfuric acid monoesters, alkylsulfonic acids (alkyl radical: C 12 -C 18 ), and alkylarylsulfonic acids (alkyl radical: C9-C 18 Further suitable emulsifiers are described in Houben-Weyl, Methoden der organischen Chemie, volume XIV / 1, Makromolekulare Stoffe, Georg-Thieme-Verlag, Stuttgart, 1961, pp. 192-208. Also suitable as anionic emulsifiers are bis(phenylsulfonic acid) ethers and phenylsulfonic acid ethers having C4-C in one or both aromatic rings. 24 These compounds, for example from U.S. Pat. No. 4,269,749, are well known and commercially available, for example in the form of Dowfax™ 2A1 (Dow Chemical Company).

[0024] Suitable cationic emulsifiers are preferably quaternary ammonium halides, such as trimethylcetylammonium chloride, methyltrioctylammonium chloride, benzyltriethylammonium chloride, or N-C6-C 20 Quaternary -alkylpyridines, -morpholines or -imidazoles, such as N-laurylpyridinium chloride.

[0025] The amount of emulsifier (or surfactant) can be at least 0.01 or 0.1 weight percent to 10 or 5 weight percent based on the amount of monomers polymerized in forming the branched polymer.

[0026] An initiator can be used to form the branched polymer. Examples of initiators include those that can be initiated by any suitable method of generating free radicals, such as by thermally induced decomposition of a thermal initiator, such as an azo compound, peroxide, or peroxyester. Therefore, the polymerization mixture also preferably contains a polymerization initiator, which can be any of those known and conventionally used in free radical polymerization reactions. Examples of azo initiators include azobis(isobutyronitrile) (AIBN), azobis(2-methylbutyronitrile), azobis(2,4-dimethylvaleronitrile), and azobis(4-cyanovaleric acid). Examples of peroxide and peroxy initiators include hydrogen peroxide, sodium peroxide, potassium peroxide, t-butyl hydroperoxide, cumene hydroperoxide, dilauroyl peroxide, tert-butyl peroxyneodecanoate, dibenzoyl peroxide, cumyl peroxide, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxydiethyl acetate, and tert-butyl peroxybenzoate.Examples of additional initiators include ammonium and / or alkali metal persulfate, sodium perborate, perphosphoric acid and its salts, potassium permanganate, and ammonium or alkali metal salts of peroxydisulfate, examples of which include alkali metal or ammonium peroxydisulfate, diacetyl peroxide, dibenzoyl peroxide, succinyl peroxide, di-tert-butyl peroxide, tert-butyl perbenzoate, tert-butyl perpivalate, tert-butyl peroxy-2-ethylhexanoate, te Examples of suitable initiators include rt-butyl permaleinate, cumene hydroperoxide, diisopropyl peroxydicarbamate, bis(o-toluoyl) peroxide, didecanoyl peroxide, dioctanoyl peroxide, dilauroyl peroxide, tert-butyl perisobutyrate, tert-butyl peracetate, di-tert-amyl peroxide, tert-butyl hydroperoxide, azobisisobutyronitrile, 2,2'-azobis(2-amidino-propane) dihydrochloride, and 2,2'-azobis(2-methylbutyronitrile). Mixtures of these initiators are also suitable. Reduction / oxidation (i.e., redox) initiator systems can also be used as initiators. Redox initiator systems consist of at least one, usually inorganic, reducing agent and one organic or inorganic oxidizing agent. The oxidizing component can include, for example, the emulsion polymerization initiators already identified above. The reducing component includes, for example, alkali metal salts of sulfite, such as sodium sulfite, sodium bisulfite, alkali metal salts of disulfite, such as sodium disulfite, bisulfite adducts of aliphatic aldehydes and ketones, such as acetone sulfite, or reducing agents such as hydroxymethanesulfinic acid and its salts, or ascorbic acid. Redox initiator systems can be used with soluble metal compounds whose metal components can exist in multiple valence states. Typical redox initiator systems include, for example, ascorbic acid / iron(II) sulfate / sodium peroxodisulfite, tert-butyl hydroperoxide / sodium disulfite, and tert-butyl hydroperoxide / Na hydroxymethanesulfinate.The individual components, for example the reducing component, may also be mixtures, an example being a mixture of the sodium salt of hydroxymethanesulfinic acid and sodium disulfite.

[0027] The amount of initiator is generally at least 0.01 or 0.05 or 0.01 weight percent to 10 or 5 or 3 weight percent based on all monomers being polymerized.

[0028] Branched polymers are not crosslinked. This can be demonstrated, for example, by assessing the solubility of the polymer in a solvent such as tetrahydrofuran. Crosslinked polymers are not soluble.

[0029] Branched polymers according to certain embodiments may be characterized by a polymer branching ratio g' of less than 1, 0.95, 0.9, or 0.8. According to some embodiments, g' is at least 0.5, 0.6, or 0.7. The polymer branching ratio (g') is determined by the ratio of the branched polymer ([η]) measured at each elution volume increment in gel permeation chromatography (GPC) analysis. 分岐 ) of a linear polymer ([η] 直鎖状 ) to the intrinsic viscosity (Equation 1). For linear polymers, the g' value is equal to 1, and for branched polymers, g' is less than 1.

number

[0030] Molecular weight analysis: absolute molecular weight of polymer (M w , M n ), PMMA relative molecular weight (M w_PMMA , M n_PMMA ), intrinsic viscosity ([η] w , [η] nThe chromatographic index (σ) and branching ratio (g') can be measured by gel permeation chromatography equipped with an online multi-angle light scattering (MALS) detector, a viscometer (VS), and a differential refractive index (dRI) detector. For example, a GPC setup can include an Agilent 1200 Series HPLC system (degasser, pump, autosampler, and column oven), a Wyatt HELEOS II MALS detector, a Wyatt ViscoStar II viscometer, and a Wyatt T-rEX dRI detector. Polymer separation can be performed, for example, with a column set containing two PLgel mixed-B LS columns (10 μm particle size, 7.5 x 300 mm length) using tetrahydrofuran (THF) as the mobile phase at a flow rate of 1 mL / min. The column oven temperature is set to 30 °C. A set of 10-point PMMA standards (Agilent EasiCal PM-1) is used to calibrate the GPC column and obtain the PMMA relative molecular weight. Absolute molecular weights are obtained from MALS detection using the Zimm format, and intrinsic viscosity data are obtained from the viscometer. High molecular weight fraction data (PMMA relative molecular weights above 6500 Da) are used to calculate average g' values. To ensure consistency in g' calculations, a linear PMMA model from the Mark-Houwink equation (Equation 2, where K = 0.0383 mL / g and α = 0.581 for the non-BA-containing samples in Table 2, and K = 0.03044 mL / g and α = 0.615 for the BA-containing polymers in Table 2) is used to calculate the ([η]) in Equation 1 using the M data from MALS detection. 直鎖状 ) is obtained. [η]=KM α (Formula 2)

[0031] The weight average molecular weight M of the branched polymer measured by GPC w According to certain embodiments, the molecular weight is in the range of at least 2,500, 3,000, 5,000, 10,000, 20,000, or 25,000 g / mol. According to certain embodiments, the weight average molecular weight is not more than 75,000 or 50,000 g / mol. According to certain embodiments, the number average molecular weight M of the branched polymer, as measured by GPC, isn is at least 1,250 or 1,500 g / mol. According to certain embodiments, the number average molecular weight is not more than 6,000 or 5,000 or 4,500 g / mol.

[0032] According to one particular embodiment, the branched structure is a dendritic structure.

[0033] The branched polymers can be used as additives without any further processing, for example, they can be used as oligomeric prepolymers for thermosetting materials.

[0034] Alternatively, the branched polymer can be blended with another polymer to form a composition. The composition can be made by blending the components. According to one embodiment, the components can be cold blended (e.g., mixing two aqueous latexes) and then freeze-dried or coagulated.

[0035] Branched polymers can also be formed as the shell of core-shell particles. For example, the core can comprise a crosslinked core of butyl acrylate (BA) and allyl methacrylate (ALMA), e.g., 99.3 weight percent BA and 0.7 weight percent ALMA. The branched polymer can then be formed on the core by emulsion polymerization.

[0036] According to certain embodiments, the thermosetting composition may include a branched polymer and an acrylic polymer or copolymer. Examples of acrylic polymers that can be used include, but are not limited to, thermoplastic vulcanizates (TPVs). Thermoplastic vulcanizates (TPVs) are elastomer / thermoplastic polymer blends in which the elastomeric phase is crosslinked and dispersed in a thermoplastic matrix during the blending process. A typical TPV is made from crosslinked EPDM (ethylene propylene diene monomer) dispersed in a polypropylene matrix. The present invention provides acrylate materials for TPV applications.

[0037] Key properties of TPV include (1) resistance to plastic deformation (i.e., low compressive and tensile hardening), (2) resistance to fluids, (3) retention of properties at elevated temperatures compared to ambient temperatures, and (4) low creep and stress relaxation.

[0038] A crosslinking agent such as an organic peroxide, preferably a high-temperature organic peroxide, can be used to initiate crosslinking in the composition. The use of a high-temperature organic peroxide allows the composition to be cured using reactive extrusion. Preferably, the high-temperature organic peroxide has a one-hour half-life temperature of at least 130°C, more preferably at least 135°C. The high-temperature organic peroxide has a one-hour half-life temperature of 250°C or less, such as 225°C or less or 200°C or less. Examples of high-temperature organic peroxides include Luperox® 101 (2,5-bis(tert-butylperoxy)-2,5-dimethylhexane), 2,3-dimethyl-2,3-diphenylbutane, bis(tert-butylperoxy)-2,5-dimethylhexane), tert-butyl hydroperoxide, tert-amyl hydroperoxide, cumyl hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, isopropyl cumyl hydroperoxide, isopropyl cumyl hydroperoxide, and the like. peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne-3,3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxonane, di(tert-butyl)peroxide, di(tert-butylperoxy-isopropyl)benzene, tert-butylcumyl peroxide, di-(tert-amyl)-peroxide, dicumyl peroxide, and butyl 4,4-di(tert-butylperoxy)valerate.

[0039] Preferably, the thermosetting composition comprises at least 1 or 3 or 5 or 10, or 20, or 30, or 50 weight percent of the branched polymer composition.

[0040] The composition may further include additional additives desired in the final product. Examples of such additives include UV light stabilizers and antioxidants. According to certain embodiments, the additives are selected so that the composition remains transparent. Examples of UV light stabilizers include benzophenones, benzotriazoles, triazines, benzoxazinones, hindered amine light stabilizers (HALS), and hindered benzoates. Commercially available UV and light stabilizers include Cyasorb light absorbers and light stabilizers from Solvay, Cyasorb Cynergy Solutions, TINUVIN FROM BASF, LowLite from Chemtura, OnCap from PolyOne, and Light Stabilizer from EI du Pont de Nemours and Company of Delaware, USA.210. Examples of antioxidants include phenolic antioxidants and combinations of phenolic antioxidants with phosphites, thioethers, or organic sulfides. Phenolic antioxidants include fully hindered and partially hindered phenols; and sterically hindered amines such as tetramethyl-piperidine derivatives. Suitable phenolic antioxidants include vitamin E and IRGANOX™ 1010 from BASF. IRGANOX™ 1010 contains pentaerythritol tetrakis(3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate). Additional examples of antioxidants include acetylcysteine, arbutin, ascorbic acid, ascorbic acid polypeptide, ascorbyl dipalmitate, methylsilanol ascorbyl pectate, ascorbyl palmitate, ascorbyl stearate, BHA, p-hydroxyanisole, BHT, t-butylhydroquinone, caffeic acid, camellia sinensis oil, chitosan ascorbate, chitosan glycolate, chitosan salicylate, chlorogenic acid, cysteine, cysteine ​​HCl, decylmercaptomethylimidazole, erythorbic acid, diamylhydroquinone, di-t-butylhydroquinone, dicetyl thiodipropionate, dicyclopentadiene / t-butylcresol copolymer. Polymer, digalloyl trioleate, dilauryl thiodipropionate, dimyristyl thiodipropionate, dioleyl tocopheryl methylsilanol, isoquercitrin, diosmin, disodium ascorbyl sulfate, disodium rutinyl disulfate, distearyl thiodipropionate, ditridecyl thiodipropionate, dodecyl gallate, ethyl ferulate, ferulic acid, hydroquinone, hydroxylamine HCl, hydroxylamine sulfate, isooctyl thioglycolate, kojic acid, madecassoside, magnesium ascorbate, magnesium ascorbyl phosphate, melatonin, methoxy-PEG-7 rutinyl succinatesuccinate), methylenedi-t-butylcresol, methylsilanol ascorbate, nordihydroguaiaretic acid, octyl gallate, phenylthioglycolic acid, phloroglucinol, potassium ascorbyl tocopheryl phosphate, thiodiglycolamide, potassium sulfite, propyl gallate, rosmarinic acid, rutin, sodium ascorbate, sodium ascorbyl / cholesteryl phosphate, sodium bisulfite, sodium erythorbate, sodium metabisulfite, sodium sulfite, sodium thioglycolate, sorbityl furfural, tea tree (melaleuca alternifolia) oil, Tocopheryl acetate, tetrahexyldecyl ascorbate, tetrahydrodiferuloylmethane, tocopheryl linoleate / oleate, thiodiglycol, tocopheryl succinate, thiodiglycolic acid, thioglycolic acid, thiolactic acid, thiosalicylic acid, thiotaurine, retinol, tocophereth-5, tocophereth-10, tocophereth-12, tocophereth-18, tocophereth-50, tocopherol, tocophersolan, tocopheryl linoleate, tocopheryl nicotinate, tocoquinone, o-tolylbiguanide, tris(nonylphenyl)phosphite, ubiquinone, zinc dibutyldithiocarbamate, and mixtures thereof. According to certain embodiments, the total amount of additives (if any) used is less than 10, 5, or 3 weight percent based on the total weight of the composition. [Example]

[0041] Synthesis of branched polymers (BMP / MMA / ALMA) Branched polymers were formed by emulsion polymerization. Emulsion polymerization was carried out in a 5-liter, four-neck round-bottom flask equipped with a mechanical stirrer, heating mantle, thermometer, temperature controller, and N2 inlet. The reactor was charged with 1530 parts deionized water, 54.55 parts sodium dodecylbenzenesulfonate surfactant (DS-4, 22% in water), 0.146 parts FeSO4, and 0.16 parts acetic acid. The reactor contents were heated to 60°C with an N2 sweep. The monomer emulsion was prepared by mixing 234 parts deionized water, 18.18 parts DS-4 surfactant (22% in water), 53 parts allyl methacrylate (ALMA), 696 parts methyl methacrylate (MMA), and 52 parts butyl 3-mercaptopropionate. Nate The monomer emulsion was prepared in a separate vessel with the BMP. Mechanical agitation was applied to induce emulsification. The total monomer emulsion was 1,000 parts. The redox initiator system consisted of two separate solutions. The first was a 3% (by weight) solution of t-butyl hydroperoxide (t-BHP) in water (oxidizer), and the second was a 3% (by weight) solution of sodium formaldehyde sulfoxylate (SFS) in water (reducer), totaling 53.33 parts. With the reactor at 60°C, simultaneous feeds (at time zero) of the t-BHP and SFS solutions were initiated at 0.44 parts / min (both 120 minutes of feed time) and the monomer emulsion at 16.67 parts / min (60 minutes of feed time). The reactor temperature was maintained at 60°C throughout the polymerization process. At the end of the monomer feed (60 minutes total reaction time from time zero), t-BHP and SFS were continued for an additional 60 minutes (120 minutes total reaction time from time zero). The reaction was then cooled to 40°C and filtered through cheesecloth. The emulsion particle size was measured to be 58 nm (by light scattering), the solids content was 30.5% (by gravimetric determination), and the residual BA and MMA monomers were both <10 ppm (by headspace gas chromatography). The polymer formed is identified as Example 8 in Table 1 below.

[0042] Other examples were prepared by the same process as above, but with different ratios of crosslinker (ALMA) to chain transfer agent (BMP). Glass transition temperatures in °C were determined by differential scanning calorimetry (DSC), and solubility was determined in tetrahydrofuran (THF). The results (average of at least two samples each) are shown in Table 1 below. In Table 1, DP refers to the degree of polymerization, i.e., the number of units of each monomer. Number average molecular weight M n was determined by GPC. [Table 1]

[0043] Examples 2, 6, 10, and 11 were determined to be crosslinked, as indicated by their low solubility in THF. Examples 1, 3, 4, 8, 9, and 12 were nearly 100% soluble in THF.

[0044] NMR spectroscopy was performed on Examples 4, 8, and 12 to determine the amount of unreacted pendant double bonds. The polymer compositions were: 13 The C NMR integrals were determined and normalized to 100%. The amount of unreacted pendant double bonds was calculated by its double carbon at approximately 132.0 ppm. The branched ALMA content was estimated based on its side chain -OCH2 ester carbon at approximately 65.0 ppm. As shown in Table 2 below, at least 80% of the pendant double bonds remained unreacted. [Table 2]

[0045] For comparison, NMR analysis was performed on a branched polymer containing 5 weight percent BMP, 2.5 weight percent 1,4-butanediol dimethacrylate (BGDMA), 5 weight percent butyl acrylate (BA), and 87.5 weight percent MMA. As expected, approximately 4% of the pendant double bonds were unreacted in this comparative sample.

[0046] Branched polymer synthesis (BMP / BMA / ALMA) Another branched polymer was prepared in a similar manner to above, except that MMA was replaced with butyl methacrylate. The composition of Example 13 is summarized in Table 3. [Table 3]

[0047] Tg was calculated using the Fox equation [Proceedings of the American Physical Society 1, 3, p. 123 (1956)] as follows:

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[0048] thermosetting polymers As described below, thermoset polymers were prepared using a first stage comprising an acrylic low Tg crosslinked core, or an acrylic low Tg crosslinked core and a high Tg shell polymer, which was then used to form an allyl-functional shell stage. The resulting polymer was then mixed with a high-temperature thermal organic peroxide to form the thermoset.

[0049] The first-stage emulsion polymerization was carried out in a 5-liter, four-neck round-bottom flask equipped with a mechanical stirrer, heating mantle, thermometer, temperature controller, and N2 inlet. The reactor was charged with 880 parts deionized water, 0.41 parts acetic acid, 2.62 parts Na2SO4, 239.96 parts acrylic rubber preform seed latex (32.0% latex solids, 59 nm), and 2.44 parts sodium formaldehyde sulfoxylate (SFS). The reactor contents were heated to 40°C with an N2 sweep. The monomer emulsion was prepared in a separate vessel with 241 parts deionized water, 72.76 parts sodium lauryl sulfate (SLS) surfactant (28% in water), 11.36 parts allyl methacrylate (ALMA), and 1599.03 parts butyl acrylate (BA). Mechanical agitation was applied to induce emulsification. The total monomer emulsion was 1924.22 parts. With the reaction at 40°C, 711.96 parts of the monomer emulsion were added along with 1.09 parts of 70% aqueous t-butyl hydroperoxide (t-BHP). After the polymerization exotherm peaked, the reaction was cooled to 54°C, and 634.99 parts of the monomer emulsion were added along with 0.77 parts of 70% aqueous t-BHP. After the polymerization exotherm peaked, the reaction was cooled to 65°C, and 577.20 parts of the monomer emulsion were added along with 0.79 parts of 70% aqueous t-BHP. After the polymerization exotherm peaked, 2 parts of 70% aqueous t-BHP and 1 part of SFS (dissolved in 50 parts of DI water) were added to the reaction. After a 15-minute hold, the reaction was cooled to 75°C. This marked the end of the acrylic rubber core. Next, a shell was prepared on the rubber core. A monomer emulsion was prepared in a separate container with 30 parts deionized water, 13.40 parts SLS surfactant (28% in water), and 112.82 parts methyl methacrylate (MMA). Mechanical agitation was applied to induce emulsification. With the reaction at 75°C, the MMA monomer emulsion was added along with 0.133 parts SFS (dissolved in 10 parts DI water) and 0.056 parts sodium persulfate (dissolved in 10 parts DI water). After the polymerization exotherm peaked, 0.67 parts 70% aqueous t-BHP and 0.48 parts SFS (dissolved in 20 parts DI water) were added to the reaction four times every 10 minutes.After a 15 minute hold, the reaction was cooled to 40°C and filtered through cheesecloth. The emulsion particle size was measured to be 169 nm (by light scattering) and the solids content was 54.2% (by gravimetric measurement).

[0050] The second stage emulsion polymerization was carried out in a 5-liter, four-neck round-bottom flask equipped with a mechanical stirrer, heating mantle, thermometer, temperature controller, and N2 inlet. The reactor was charged with 779.71 parts deionized water, 1290.56 parts acrylic core-shell, Stage (C), (54.2% latex solids), 0.055 parts FeSO4, and 1.5 parts methyl-β-cyclodextrin. The reactor contents were heated to 60°C with an N2 sweep. The monomer emulsion consisted of 67.23 parts deionized water, 27.27 parts DS-4 surfactant (22% in water), 19.5 parts allyl methacrylate (ALMA), 182.70 parts methyl methacrylate (MMA), 78.3 parts lauryl methacrylate (LMA), and 19.5 parts butyl 3-mercaptopropionate. Nate The monomer emulsion was prepared in a separate vessel containing t-butyl hydroperoxide (t-BHP). Mechanical agitation was applied to induce emulsification. The total monomer emulsion was 375 parts. The redox initiator system consisted of two separate solutions. The first was a 3% (by weight) solution of t-butyl hydroperoxide (t-BHP) in water (oxidizer), and the second was a 3% (by weight) solution of sodium formaldehyde sulfoxylate (SFS) in water (reducer), totaling 30.00 parts. With the reactor at 60°C, simultaneous feeds (at time zero) of the t-BHP and SFS solutions were initiated at 0.25 parts / min (both 120 minutes of feed time) and the monomer emulsion at 6.25 parts / min (60 minutes of feed time). The reactor temperature was maintained at 60°C throughout the polymerization process. At the end of the monomer feed (60 minutes total reaction time from time zero), t-BHP and SFS were continued for an additional 60 minutes (120 minutes total reaction time from time zero). The reaction was then cooled to 40°C and filtered through cheesecloth. The emulsion particle size was measured to be 184 nm (by light scattering) and the solids content was 36.7% (by gravimetric measurement).

[0051] Polymer powder samples were isolated by freeze-drying using a vacuum oven. The peroxide Luperox 101 (1.5%) was incorporated prior to isolation (peroxide pre-dispersed in DI water containing 6.7% surfactant DS4).

[0052] Powder samples with and without peroxide were processed using a CARVER press (Carver Press Inc., Menomonee Falls, Wisconsin) with an operating temperature of 160°C and pressing conditions of 2.268 tons for 3 minutes, followed by 185°C at 9.07 tons for 5 minutes, and a cooling period (room temperature) at 9.07 tons for 5 minutes.

[0053] Dynamic mechanical analysis (DMA) testing was performed on a Rheometrics Mechanical Spectrometer (RMS-800) using an 8 mm diameter aluminum disposable plate fixture. Using the dynamic temperature ramp mode, samples were tested from 150 °C to -80 °C at a cooling rate of 2 degrees / min using an applied frequency of 6.28 rad / s. The AutoStrain option was used for testing, with an initial strain of 0.2% and a maximum strain limit of 5% to ensure test conditions remained in the linear viscoelastic regime. The fixture was zeroed at the initial test temperature of 150 °C. Sample thickness was measured using the instrument's micrometer after loading the sample between the parallel plates. Testing began after equilibrating at 150 °C for approximately 10 minutes. Dynamic storage G' was recorded as a function of temperature for each sample. The figure shows DMA Ga overlays of plaques with and without Luperox 101. [Table 4]

Claims

1. A branched polymer, the branched polymer is a reaction product of reactants comprising one or more monoethylenically unsaturated ester monomers, a chain transfer agent in an amount from 3 to 15 weight percent, and a crosslinker in an amount from 3 to 15 weight percent; Weight percentages are based on the total amount of reactants, provided that the amount of said crosslinking agent is within ±5 weight percent of the amount of said chain transfer agent; the crosslinker comprises at least two carbon-carbon double bonds of different reactivity; the crosslinker is selected from the group consisting of allyl methacrylate, allyl acrylate, and combinations thereof; A branched polymer wherein at least 80% of the pendant double bonds derived from said crosslinker remain unreacted.

2. 2. The branched polymer of claim 1, wherein the one or more monoethylenically unsaturated ester monomers have the structure R'-C(O)O-R, where R is a hydrocarbyl group of 1 to 12 carbon atoms and R' is a monoethylenically unsaturated aliphatic group having at least 2 or 3 carbon atoms.

3. 3. The branched polymer of claim 2, wherein the one or more monoethylenically unsaturated ester monomers are selected from methyl methacrylate and butyl methacrylate.

4. The chain transfer agent may be selected from the group consisting of propyl mercaptan, butyl mercaptan, hexyl mercaptan, octyl mercaptan, dodecyl mercaptan, thioglycolic acid, mercaptopropionic acid, alkyl thioglycolate, mercaptoethanol, mercaptoundecanoic acid, thiolactic acid, thiobutyric acid, trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetra(3-mercaptopropionate), pentaerythritol tetrathioglycolate, pentaerythritol tetras(3-mercaptopropionate), ...

4. The branched polymer according to claim 1, wherein the branched polymer is selected from the group consisting of thritol tetrathiolactate, pentaerythritol tetrathiobutyrate, dipentaerythritol hexa(3-mercaptopropionate), dipentaerythritol hexathioglycolate, tripentaerythritol octa(3-mercaptopropionate), tripentaerythritol octathioglycolate, butyl 3-mercaptopropionate, and combinations of two or more thereof.

5. The branched polymer of any one of claims 1 to 4, wherein the amount of the crosslinker is from 3 to 10 percent by weight.

6. 6. The branched polymer of claim 1, wherein the amount of the chain transfer agent is from 3 to 10 percent by weight.

7. 7. The branched polymer of claim 1, wherein the amount of the crosslinking agent is within ±3 weight percent of the amount of the chain transfer agent.

8. A thermosetting composition comprising an acrylic polymer and the branched polymer of any one of claims 1 to 7.

9. The thermosetting composition of claim 8 , wherein the branched polymer is grafted to the acrylic polymer.

10. A molded article formed from the thermosetting composition according to claim 8 or 9.

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