One-step process for making silicone impact modifiers

Abstract

The one-step process for preparing the silicone impact modifier includes polymerizing a reaction mixture that includes a telechelic methacrylate-functional silicone and at least one alkyl (meth)acrylate.

Description

[Technical field]

[0001] The present invention relates generally to a one-step process for producing silicone impact modifiers. [Background technology]

[0002] Silicone acrylic core-shell-rubber (CSR) impact modifiers are often used in a variety of thermoplastic resins, including polycarbonate (PC). These impact modifiers often have a crosslinked silicone core with a grafted methyl methacrylate (MMA) shell. These silicone acrylic CSR impact modifiers are typically prepared by a two-stage polymerization process, a free radical process in which the silicone rubber stage is the polymerization of silanes or silicones, and the shell stage is prepared by conventional emulsion polymerization.

[0003] Alternatively, US Patent Application Publication No. 2021 / 0317247 discloses the use of telechelic (α,ω) methacrylate-functional linear polydimethylsiloxane (PDMS). Telechelic methacrylate-functional silicones cannot be prepared by conventional emulsion polymerization because the material has negligible water solubility. Therefore, miniemulsion polymerization was used to prepare latex particles via free radical polymerization of the methacrylate end groups of telechelic methacrylate-functional silicones. Miniemulsion polymerization involves the direct polymerization of latex-sized droplets (100-500 nm). The process disclosed by US Patent Application Publication No. 2021 / 0317247 required a two-stage polymerization process to synthesize silicone acrylic core-shell rubber. In the first step, the telechelic methacrylate-functional silicone had to be diluted with butyl acrylate (BA) monomer to prepare the first rubber stage of the miniemulsion impact modifier. In the second step, the methyl methacrylate (MMA) shell was prepared by conventional emulsion polymerization. Due to the need for dilution of the telechelic methacrylate-functional silicone in the first step, high silicone loadings are not possible in the two-step polymerization process.

[0004] There is a need to develop new processes for preparing silicone acrylic impact modifiers. Summary of the Invention

[0005] One aspect of the invention provides a process for preparing a silicone impact modifier, the process comprising polymerizing a reaction mixture comprising a telechelic methacrylate functional silicone and at least one alkyl (meth)acrylate. [Brief description of the drawings]

[0006] [Figure 1]1 is a graph comparing the impact performance of a silicone acrylic impact modifier prepared according to the process of the present invention with a commercially available impact modifier and a silicone acrylic impact modifier prepared according to a comparative process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] The present inventors have surprisingly discovered that silicone core acrylic shell impact modifiers can be prepared in a one-step process.

[0008] As used herein, the term "polymer" refers to a polymeric compound prepared by polymerizing monomers, whether of the same or different types. The general term "polymer" includes the terms "homopolymer," "copolymer," "terpolymer," and "resin." As used herein, the term "polymerized units derived from" refers to a polymer molecule synthesized according to a polymerization technique in which the product polymer contains "polymerized units derived from" the constituent monomers that are the starting materials for the polymerization reaction. As used herein, the term "(meth)acrylate" refers to either acrylate or methacrylate or a combination thereof, and the term "(meth)acrylic" refers to either acrylic or methacrylic or a combination thereof. As used herein, the term "substituted" refers to having at least one attached chemical group, such as an alkyl group, an alkenyl group, a vinyl group, a hydroxyl group, a carboxylic acid group, other functional groups, and combinations thereof.

[0009] As used herein, the term "multi-stage polymer" refers to a polymer made by forming (i.e., polymerizing) a first polymer, referred to as the "first stage" or "first stage polymer," which forms the core of the multi-stage polymer. Then, in the presence of the first stage, a second polymer, referred to as the "second stage" or "second stage polymer," is formed, which may be an intermediate or final stage of the multi-stage polymer. The multi-stage polymer may contain additional stages, which may be formed before or after the second stage polymer. Each intermediate stage is formed in the presence of the polymer resulting from the polymerization of the stage immediately preceding it. In such embodiments, where each subsequent stage forms a partial or complete shell around each particle remaining from the previous stage, the resulting multi-stage polymer is known as a "core / shell" polymer, where the first stage polymer comprises the core, each subsequent stage comprises a shell on the preceding stage, and the final stage forms the outermost shell. Thus, the second stage polymer constitutes at least a portion of the shell in the multi-stage polymer.

[0010] Previously known processes for preparing silicone acrylic impact modifiers required a multi-step process in which a silicone polymer or silicone acrylic copolymer was first prepared, followed by a subsequent step of polymerizing an acrylic shell onto the silicone core.

[0011] As used herein, "weight average molecular weight" or "M w The term "weight of polymer" refers to the weight average molecular weight of the polymer as measured by gel permeation chromatography (GPC) for acrylic acid polymers against polystyrene calibration standards according to ASTM D5296-11 (2011) and using tetrahydrofuran (THF) as the mobile phase and diluent. As used herein, the term "weight of polymer" refers to the dry weight of the polymer.

[0012] The process according to the present invention is a one-step process of polymerizing a reaction mixture containing telechelic methacrylate functional silicone and at least one alkyl (meth)acrylate. Without wishing to be bound by theory, it is believed that an acrylic polymer, for example, poly(methyl methacrylate) (PMMA), phase separates from silicone when at least one alkyl (meth)acrylate is methyl methacrylate formed in the polymerization reaction phase, even when the acrylic polymer and silicone are covalently bonded to each other between the end group of the silicone and at least one alkyl (meth)acrylate, and further, the acrylic polymer preferentially forms a shell due to the more hydrophilic nature of the alkyl (meth)acrylate and the more hydrophobic nature of the silicone. This has been experimentally observed by atomic force microscopy (AFM), where the silicone phase and the PMMA phase are clearly distinguished.

[0013] The telechelic methacrylate functional silicone preferably has the formula:

[0014] [ka] (wherein each R is independently hydrogen or a hydrocarbon group, n is 0 to 1, and all R' are independently organic groups containing one or more ethylenically unsaturated groups).

[0015] Preferred R groups are hydrogen and hydrocarbon groups having 12 or fewer carbon atoms, more preferably hydrogen and hydrocarbon groups having 8 or fewer carbon atoms, more preferably hydrocarbon groups having 4 or fewer carbon atoms, more preferably methyl groups. 1 The groups are the same as each other.

[0016] Preferred -R' groups have the structure:

[0017] [ka] where R" is a hydrocarbon group, preferably an alkyl group. Preferably, R" has 8 or fewer carbon atoms, more preferably 5 or fewer, more preferably 3 or fewer carbon atoms. Preferably, R" has 1 or more carbon atoms, more preferably 2 or more carbon atoms, more preferably 3 or more carbon atoms. R'" is either hydrogen or methyl, preferably methyl. Preferably, all R' groups are the same as each other.

[0018] In telechelic methacrylate functional silicones, n is preferably 10 or greater, more preferably 20 or greater, more preferably 50 or greater, more preferably 100 or greater. In telechelic methacrylate functional groups, n is preferably 800 or less, more preferably 500 or less, more preferably 300 or less.

[0019] The silicone polymer may also contain polymerized units of one or more monovinyl acrylic monomers. Preferred monovinyl acrylic monomers are acrylic acid, methacrylic acid, their unsubstituted alkyl esters, their substituted alkyl esters, and mixtures thereof. More preferred are acrylic acid, methacrylic acid, their unsubstituted alkyl esters, and mixtures thereof. More preferred are one or more unsubstituted alkyl esters of acrylic acid or methacrylic acid. More preferred are one or more unsubstituted alkyl esters of acrylic acid. More preferred are one or more unsubstituted alkyl esters of acrylic acid. Of the unsubstituted alkyl esters of acrylic acid and methacrylic acid, those in which the alkyl group has 18 or less carbon atoms, more preferably 8 or less carbon atoms, more preferably 6 or less carbon atoms, more preferably 4 or less carbon atoms are preferred. Of the unsubstituted alkyl esters of acrylic acid and methacrylic acid, those in which the alkyl group has 2 or more carbon atoms, more preferably 4 or more carbon atoms are preferred.

[0020] Preferably, the telechelic methacrylate functional silicone is present in the reaction mixture in an amount that constitutes 50-95% by weight of the total weight of the telechelic methacrylate functional silicone and the at least one alkyl (meth)acrylate in the reaction mixture. For example, the telechelic functional silicone is present in the reaction in an amount of at least 60% by weight or at least 70% by weight and up to 90% by weight or up to 85% by weight of the total weight of the telechelic methacrylate functional silicone and the at least one alkyl (meth)acrylate in the reaction mixture.

[0021] The at least one alkyl (meth)acrylate is preferably a linear or branched C1-C 12 The alkyl group includes a methyl, ethyl, propyl, butyl, hexyl, 2-ethylhexyl, and octyl group. Preferably, the at least one alkyl (meth)acrylate includes methyl methacrylate.

[0022] The at least one alkyl (meth)acrylate may comprise a mixture of two or more alkyl (meth)acrylates. For example, the reaction mixture may comprise methyl methacrylate and butyl acrylate.

[0023] The reaction mixture may include at least one additional monomer. For example, the reaction mixture may include at least one additional monomer selected from an organophosphorus monomer, a styrene (e.g., styrene sulfonic acid, acrylic acid, or methacrylic acid).

[0024] Examples of organophosphorus monomers include:

[0025] [ka] wherein R is an organic group containing an acryloxy, methacryloxy, 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 which also contain polymerizable vinyl or olefinic groups, such as allyl phosphate, mono- or diphosphates of bis(hydroxy-methyl)fumarates or itaconates, derivatives of (meth)acrylic acid esters, such as phosphates of hydroxyalkyl (meth)acrylates, including 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and the like.

[0026] Other suitable organophosphorus monomers include CH2=C(R)-C(O)-O-(R'O) such as, for example, the methacrylates SIPOMER™ PAM-100, SIPOMER™ PAM-200, SIPOMER™ PAM-400, SIPOMER™ PAM-600 and the acrylate, SIPOMER™ PAM-300, available from Solvay. n -P(O)(OH)2, where R=H or -CH3, R'=alkyl, and n=1-5.

[0027] Other suitable organophosphorus monomers are the phosphonate functional monomers disclosed in WO 99 / 25780 A1, including vinyl phosphonic acid, allyl phosphonic acid, 2-acrylamido-2-methylpropane phosphonic acid, α-phosphonostyrene, 2-methylacrylamido-2-methylpropane phosphonic acid. Further suitable organophosphorus monomers are the 1,2-ethylenically unsaturated (hydroxy)phosphinyl alkyl (meth)acrylate monomers disclosed in U.S. Pat. No. 4,733,005, including (hydroxy)phosphinyl methyl methacrylate.

[0028] Preferably, the organophosphorus monomer has the formula CH2=C(R)-C(O)-O-(R'O) nMore preferably, R is -CH3, R' is an alkyl group containing 1 to 6 carbon atoms, and n=1.

[0029] When present, the at least one additional monomer may be present in the reaction mixture in an amount constituting 0.01 to 10% by weight based on the total weight of the at least one alkyl (meth)acrylate and the at least one additional monomer in the reaction mixture. For example, the at least one additional monomer may be present in the reaction mixture in an amount constituting at least 0.25%, at least 0.5%, or at least 1% by weight of the total weight of the at least one alkyl (meth)acrylate and the at least one additional compound in the reaction mixture. The at least one additional monomer may be present in the reaction mixture in an amount constituting 8% or less, 6% or less, 5% or less, or 4% or less by weight of the total weight of the at least one alkyl (meth)acrylate and the at least one additional monomer in the reaction mixture.

[0030] The reaction may further include a crosslinking agent. The crosslinking agent may be any polyfunctional unsaturated monomer, i.e., any monomer with two or more unsaturated groups available for addition polymerization. Examples of suitable difunctional monomers include ethylene glycol di(meth)acrylate, hexanediol di(meth)acrylate, tripropylene glycol di(meth)acrylate, butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, allyl (meth)acrylate, divinylbenzene, and derivatives thereof. Examples of trifunctional include tripropylene glycol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate. Tetrafunctional monomers such as pentaerythritol tetra(meth)acrylate and hexafunctional monomers, for example, dipentaerythritol hexa(meth)acrylate, can also be used. Optionally, the multifunctional monomer can include a mixture of two or more multifunctional compounds.

[0031] The crosslinker may be present in an amount ranging from 0.1 to 10 weight percent based on the total weight of the telechelic methacrylate functional silicone and the at least one alkyl (meth)acrylate.

[0032] The reaction mixture is preferably polymerized by emulsion polymerization, more preferably by miniemulsion polymerization, which involves the direct polymerization of latex-sized droplets (e.g., 100-500 nm droplets) using either a high-pressure homogenizer or an ultrasonic processor.

[0033] Preferably, the silicone acrylic impact modifier is produced in the form of latex. As used herein, the term "latex" refers to the physical form of polymer in which the polymer exists in the form of small polymer particles dispersed in water. The latex can have, for example, an average particle size of 50 nm or more, or 100 nm or more. The latex can have an average particle size of 1,000 nm or less, or 800 nm or less, or 600 nm or less. The latex can be separated into powder by coagulation or spray drying.

[0034] Preferably, most or all of the water remaining with the isolated polymer is removed from the isolated polymer by one or more of the following procedures: filtration (including, for example, vacuum filtration) and / or centrifugation. The isolated polymer may optionally be washed one or more times with water.

[0035] Preferably, the dried silicone acrylic impact modifier has a water content of less than 1.0 weight percent based on the weight of the dried silicone acrylic impact modifier.

[0036] The dried silicone acrylic impact modifier can then be incorporated into a matrix resin composition containing the impact modifier and matrix resin. After the mixture of silicone acrylic impact modifier and matrix resin is mixed, melted, and molded into a solid product, the impact resistance of the product will be better than the same solid product made with a matrix resin that is not mixed with the silicone acrylic impact modifier. The impact modifier can be provided in a solid form, such as pellets or powder, or a mixture thereof. The matrix resin can also be provided in a solid form, such as pellets or powder, or a mixture thereof.

[0037] Suitable matrix resins include, for example, polyolefins, polystyrene, styrene copolymers, poly(vinyl chloride), poly(vinyl acetate), acrylic polymers, polyethers, polyesters, polycarbonates, polyurethanes, and polyamides. Preferably, the matrix resin contains at least one polycarbonate. Suitable polycarbonates also include, for example, homopolymers of polymerized units derived from bisphenol A ("Bisphenol A, BPA"), and copolymers that include polymerized units of BPA together with one or more other polymerized units.

[0038] The process for preparing the silicone acrylic impact modifiers of the present invention can significantly improve the time and complexity required to prepare silicone acrylic impact modifiers while still providing similar impact performance.

[0039] Some embodiments of the present invention are described in detail in the following examples. EXAMPLES

[0040] Particle size measurement The particle size of the oligomers was measured with a Malvern Zetasizer Nano S90 particle size analyzer.

[0041] Comparative Example - Synthesis of Silicone Acrylic Impact Modifier A comparative example was prepared using a two-step process. Step 1: A 5 liter glass 4-neck round bottom flask was fitted with a mechanical stirrer, thermometer, condenser, and electric heating mantle. The reactor was charged with 480.22 g of deionized water and 0.075 g of Sequestrene. The reactor contents were heated to 50°C. In a separate vessel, 600 g of telechelic methacrylated silicone (n=62), 196 g of butyl acrylate, 4 g of allyl methacrylate, 18.18 g of a 23% aqueous solution of sodium dodecylbenzenesulfonate, and 790 g of deionized water were blended and stirred to form a monomer emulsion mixture. The monomer emulsion was then further processed into a mini-emulsion using a Misonix® sonicator. The monomer mini-emulsion was added to the reactor and the reactor temperature was adjusted to 50°C. Then 20 g of a 2.5% aqueous solution of t-butyl hydroperoxide and 20 g of a 2.5% aqueous solution of sodium formaldehyde sulfoxylate were added, followed by simultaneous feeding of another 20 g each of t-butyl hydroperoxide and sodium formaldehyde sulfoxylate (both 2.5% aqueous solutions) over 30 minutes, followed by a 30 minute hold while the reactor temperature was adjusted to 60° C. Step 2: In a separate vessel, a monomer emulsion was prepared using 4 g butyl acrylate, 196 g methyl methacrylate, 4.55 g of a 23% aqueous solution of sodium dodecylbenzenesulfonate, and 50 g deionized water. This monomer emulsion was added to 20 g of a 2.5% aqueous solution of t-butyl hydroperoxide and 20 g of a 2.5% aqueous solution of sodium formaldehyde sulfoxylate, followed by another 20 g each of t-butyl hydroperoxide and sodium formaldehyde sulfoxylate (both 2.5% aqueous solutions) being simultaneously fed over 30 minutes while the reactor temperature was held at 60° C., followed by a 30 minute hold. The reaction was then cooled to 40° C. and filtered. The particle size was measured to be 340 nm and the solids content was 39.6%.

[0042] Comparative Example Solidification To a 4 liter beaker, 4.8 g of solid calcium chloride and 1162 g of deionized water were added. The contents of the beaker were heated to 80° C. while stirring at 500 rpm. Once the temperature reached 80° C., a preheated mixture of 442 g of the above silicone acrylic emulsion at 80° C. and 133 g of deionized water was slowly added to the vessel, followed by a solution of 0.9 g of calcium chloride dissolved in 45 g of deionized water. The mixture was then heated to 95° C. and held at 95° C. for 30 minutes. After holding, the mixture was cooled, dehydrated, and washed in a Buchner funnel. The sample was washed with deionized water until the conductivity of the filtrate was less than 30 μS / m, and then dehydrated. The sample was dried in a vacuum oven to a powder.

[0043] Example of the Invention - Synthesis of Silicone Acrylic Impact Modifier The inventive examples were prepared using a one-step process. A 5 liter glass 4-neck round bottom flask was fitted with a mechanical stirrer, thermometer, condenser, and electric heating mantle. The reactor was charged with 244 g of deionized water and 0.075 g of Sequestrene. The reactor contents were heated to 80°C. In a separate vessel, 800 g of telechelic methacrylated silicone (n=62), 4 g of butyl acrylate, 196.00 g of methyl methacrylate, 22.73 g of a 23% aqueous solution of sodium dodecylbenzenesulfonate, and 995 g of deionized water were blended and stirred to form a monomer emulsion mixture. The monomer emulsion was then further processed into a mini-emulsion using a Misonix® sonicator. The resulting mini-emulsion was added to the reactor and the reactor temperature was adjusted to 40°C. Simultaneous 90 minute feeds of 80.0 g of a 2.5% aqueous solution of t-butyl hydroperoxide and 80.0 g of a 2.5% aqueous solution of sodium formaldehyde sulfoxylate were then started. After 15 minutes, the reactor temperature was adjusted to 65° C., then after another 45 minutes to 85° C. At the end of the 90 minute feeds of t-butyl hydroperoxide and sodium formaldehyde sulfoxylate, the reactor was held at 85° C. for 30 minutes, then cooled to 40° C. and filtered. The final emulsion solids content was determined to be 40.7% and the particle size was 366 nm.

[0044] Solidification of the embodiment of the present invention To a 4 liter beaker, 4.8 g of solid calcium chloride and 1162 g of deionized water were added. The contents of the beaker were heated to 80° C. while stirring at 500 rpm. Once the contents reached 80° C., a preheated mixture of 430 g of the above silicone acrylic emulsion at 80° C. and 152 g of deionized water was slowly added to the vessel, followed by a solution of 0.9 g of calcium chloride dissolved in 45 g of deionized water. The mixture was then heated to 95° C. and held at 95° C. for 30 minutes. After holding, the mixture was cooled, dehydrated, and washed in a Buchner funnel. The sample was washed with deionized water until the conductivity of the filtrate was less than 30 μS / m, and then dehydrated. The sample was dried in a vacuum oven to a powder. AFM imaging confirmed that the comparative example and the inventive example had similar morphology.

[0045] [Table 1]

[0046] Application test formulation Polycarbonate resin is made by compounding the impact modifier produced by the method of comparative example and the embodiment of the present invention and commercial impact modifiers, including EXL2691J, MBS CSR impact modifier from The Dow Chemical Company; Kane Ace MR-01, silicone impact modifier from Kaneka; and Metablen SX005, silicone impact modifier from Mitsubishi Chemical.The graph in Figure 1 shows that the silicone acrylic impact modifier made by the one-step process of the present invention shows similar impact performance compared to commercial impact modifiers.

[0047] [Table 2]

[0048] Laboratory made Si-AIM samples at a loading level of 5% were bag mixed with pelletized PC pellets and the other ingredients in Table 2 above, then compounded using a 30 mm Werner Pfleiderer twin screw extruder at the processing conditions listed in Table 3 below.

[0049] [Table 3]

[0050] Notched Izod impact strength was completed according to ASTM D256. Five impact specimens were placed in a temperature controlled environment (23°C / 50% RH) for at least 40 hours. Once sample preparation was complete, the specimens were tested at 23°C, 0°C, -20°C, and -30°C to understand the ductile / brittle transition.

Claims

1. 1. A one-step process for preparing a silicone impact modifier, comprising: A one-step process comprising polymerizing a reaction mixture comprising a telechelic methacrylate-functional silicone and at least one alkyl (meth)acrylate.

2. 10. The process of claim 1, wherein the telechelic methacrylate functional silicone is a compound of the following formula: 【Chemistry 1】 wherein each R is independently hydrogen or a hydrocarbon group, n is 0 to 1,000, and R′ is a group having the structure: 【Chemistry 2】 wherein each R" is a hydrocarbon group and each R'" is hydrogen or methyl.

3. 3. The process of claim 2, wherein each R is independently hydrogen or a hydrocarbon group containing 12 or fewer carbon atoms and each R" is a hydrocarbon group containing 8 or fewer carbon atoms.

4. 3. The process of claim 2, wherein each R is independently a hydrocarbon group containing 4 or fewer carbon atoms.

5. 3. The process of claim 2, wherein each R'' is a hydrocarbon group containing no more than 3 carbon atoms.

6. 3. The process of claim 2, wherein each R is a methyl group, each R" is a methyl group, and each R'" is a methyl group.

7. 10. The process of claim 1, wherein the telechelic methacrylate-functional silicone is present in the reaction mixture in an amount that comprises 50 to 95 weight percent of the total weight of the telechelic methacrylate-functional silicone and the at least one alkyl (meth)acrylate in the reaction mixture.

8. 8. The process of claim 7, wherein the telechelic methacrylate-functional silicone is present in the reaction mixture in an amount that comprises 60 to 90 weight percent of the total weight of the telechelic methacrylate-functional silicone and the at least one alkyl (meth)acrylate in the reaction mixture.

9. 10. The process of claim 1, wherein the reaction mixture further comprises at least one additional monomer selected from an organophosphorus monomer, styrene, acrylic acid, and methacrylic acid.

10. 10. The process of claim 9, wherein at least one monomer is present in the reaction mixture in an amount comprising 0.01 to 10 weight percent based on the total weight of the at least one alkyl (meth)acrylate and the at least one additional monomer in the reaction mixture.

11. The at least one alkyl (meth)acrylate is a linear or branched C １ ~C １２ The process of claim 1 , comprising an alkyl group.

12. The process of claim 11, wherein the at least one alkyl (meth)acrylate comprises an alkyl group selected from the group consisting of methyl, ethyl, propyl, butyl, hexyl, 2-ethylhexyl, and octyl groups.

13. 13. The process of claim 12, wherein the at least one alkyl (meth)acrylate comprises methyl methacrylate.

14. 13. The process of claim 12, wherein the at least one alkyl (meth)acrylate comprises methyl methacrylate and butyl acrylate.

15. The process of any one of claims 1 to 14, wherein polymerizing the reaction mixture comprises emulsion polymerizing the reaction mixture.

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