EP4337633A1 - Ungesättigte ester, enthaltend ein additiv zur reduktion und stabilisierung des gelbwertes - Google Patents

Ungesättigte ester, enthaltend ein additiv zur reduktion und stabilisierung des gelbwertes

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Publication number
EP4337633A1
EP4337633A1 EP22727014.7A EP22727014A EP4337633A1 EP 4337633 A1 EP4337633 A1 EP 4337633A1 EP 22727014 A EP22727014 A EP 22727014A EP 4337633 A1 EP4337633 A1 EP 4337633A1
Authority
EP
European Patent Office
Prior art keywords
ppm
alkyl
meth
weight
composition
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP22727014.7A
Other languages
German (de)
English (en)
French (fr)
Inventor
Florian Zschunke
Andrea Wittkowski
Belaid AIT AISSA
Rudolf Burghardt
Daniel Helmut König
Steffen Krill
Andreas RÜHLING
Sven Balk
Bruno Keller
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Roehm GmbH Darmstadt
Original Assignee
Roehm GmbH Darmstadt
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Roehm GmbH Darmstadt filed Critical Roehm GmbH Darmstadt
Publication of EP4337633A1 publication Critical patent/EP4337633A1/de
Pending legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C67/00—Preparation of carboxylic acid esters
    • C07C67/48—Separation; Purification; Stabilisation; Use of additives
    • C07C67/62—Use of additives, e.g. for stabilisation
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C69/00—Esters of carboxylic acids; Esters of carbonic or haloformic acids
    • C07C69/52—Esters of acyclic unsaturated carboxylic acids having the esterified carboxyl group bound to an acyclic carbon atom
    • C07C69/533—Monocarboxylic acid esters having only one carbon-to-carbon double bond
    • C07C69/54—Acrylic acid esters; Methacrylic acid esters

Definitions

  • the present invention relates to a novel process for reducing the yellowness index of alkyl (meth)acrylates, in particular of MMA, and of polymers produced from these alkyl (meth)acrylates.
  • the novel process also develops this effect after the monomers have been stored for a long period of time.
  • the process involves the addition of specific aldehydes into the monomer composition. This can be done independently of the respective manufacturing process for the alkyl (meth)acrylates and is therefore easy and inexpensive to implement.
  • methyl methacrylate is produced using various processes that start from C2, C3 or C4 building blocks, still predominantly starting from hydrocyanic acid and acetone via the resulting acetone cyanohydrin (ACH) as the central intermediate.
  • This process has the disadvantage that very large amounts of ammonium sulfate are obtained, the processing of which is associated with very high costs.
  • Other processes that use a raw material basis other than ACH are described in the relevant patent literature and have meanwhile been implemented on a production scale.
  • Another disadvantage is that the C3-based MMA produced does not have optimal yellowness values. Although these are relatively small, they still lead to troublesome slight yellowing, particularly in the production of PMMA sheets, films or molded parts which are used in optically relevant applications.
  • starting materials such as isobutylene or tert-butanol are used, which are converted into the desired methacrylic acid derivatives over several process stages. These are oxidized in a first stage to methacrolein and in a second stage to methacrylic acid. Finally, an esterification takes place to give the desired alkyl ester, in particular with methanol to give MMA. More details on this method are, inter alia, in Ullmann's Encyclopedia of Industrial Chemistry 2012, Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, Methacrylic Acid and Derivatives, DOI: 10.1002/14356007.
  • isobutylene or tert-butanol is generally oxidized to form methacrolein in a first stage, which is then reacted with oxygen to form methacrylic acid.
  • the methacrylic acid obtained is subsequently converted into MMA with methanol. Further details on this method are available in Ullmann's Encyclopedia of Industrial Chemistry 2012, Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, Methacrylic Acid and Derivatives, DOI:
  • Raw materials used include, for example, tert-butanol, which is converted to isobutene by eliminating water, alternatively methyl tert-butyl ether, which is converted to isobutene by eliminating methanol, or isobutene itself, which is available as a raw material from a cracker, for example .
  • Process A "Tandem C Direct Oxidation" process, without intermediate isolation of methacrolein:
  • isobutene is used to produce methacrolein, which is oxidized to methacrylic acid in step 2, before finally esterifying it with methanol in step 3 to form MMA becomes.
  • Method B "Separate C Direct Oxidation" method:
  • methacrolein is produced from isobutene, which is first isolated and intermediately purified in step 2, before it is converted into methacrylic acid in step 3 and this finally in step 4 with it methanol is esterified to MMA.
  • Method C "Direct Metha Process” or direct oxidative esterification process:
  • methacrolein is produced in a first step from isobutene, which is first isolated and intermediately cleaned in step 2 before it is mixed with methanol and air in step 3 is directly oxidatively esterified to MMA.
  • C4-based MMA without a very complex multi-stage purification with loss of product is also easy to achieve, but still optical yellowing in end-use applications. Basically, and even if disturbing, the yellowing of C4-based products tends to be somewhat less than that of C3-based products. This yellowing could persist somewhat, though 3 cannot be sufficiently reduced by providing an alternative C4-based method.
  • MMA is obtained by oxidizing isobutylene or tert-butanol with atmospheric oxygen in the gas phase at heterogeneous contact to form methacrolein and subsequent oxidative esterification reaction of methacrolein using methanol.
  • This method developed by ASAHI, is described, inter alia, in the publications US Pat. No. 5,969,178 and US Pat. No. 7,012,039. A disadvantage of this method is in particular a very high energy requirement.
  • the methacrolein is obtained from propanal and formaldehyde in the first stage. Such a method is described in WO 2014/170223. However, even with this optimization, it is often found that C4-based MMA also often has relevant residual yellow values.
  • US Pat. No. 5,969,178 discloses working up in just one column, with the feed necessarily being above the bottom. Low-boiling constituents are removed from the reactor discharge at the top of this column. A mixture of crude MMA and water remains in the sump and is to be sent for further processing. A mixture of methacrolein and methanol, intended for recycling into the reactor, is finally removed from the column via a side stream, the exact position of which must first be determined and which can be adjusted by adding various boiling trays. US Pat. No. 5,969,178 itself points out that such a method is difficult to carry out because of various azeotropes.
  • methacrylic acid in particular which is always present as a by-product, plays a major role. According to this process, even if US Pat. No. 5,969,178 is silent about this, the methacrylic acid would be separated off in such a way that it remained in a phase to be disposed of and isolation would only be worthwhile to a limited extent. However, this reduces the overall yield of methacrylic products from this process.
  • US Pat. No. 7,012,039 discloses a somewhat different work-up of the reactor effluent from the oxidative esterification.
  • methacrolein is distilled off overhead via sieve trays and the aqueous, MMA-containing mixture is passed from the bottom into a phase separator.
  • the mixture is adjusted to a pH of about 2 to 3 by adding sulfuric acid.
  • the sulfuric acid water is then separated from the organic or oil phase by means of centrifugation.
  • this oil phase is separated into high-boiling components and a phase containing MMA, which is drawn off overhead.
  • the MMA-containing phase is then separated from low-boiling components in a third distillation. This is followed by a fourth distillation for final purification.
  • WO 2014/170223 describes a similar method to US 7,012,039. The only difference is that in the actual reaction, the pH value is adjusted by adding a methanolic sodium hydroxide solution in a circuit. This serves, among other things, to protect the catalytic converter. Furthermore, the separation of the aqueous phase in the phase separation is easier due to the salt content. However, it also means that some of the methacrylic acid formed is present as the sodium salt and is later separated off with the aqueous phase and discarded. In the case of the variant of adding sulfuric acid in the phase separation, the free acid is indeed recovered. However, sodium (hydrogen) sulfate accumulates, which can lead to other problems during disposal.
  • WO 2017/046110 teaches an optimized processing of the crude MMA obtained from an oxidative esterification by first separating it from a heavy phase and then distilling off an alcohol-containing light phase from this heavy phase, which in turn can be recycled.
  • the methacrolein was obtained on the basis of propanal and formaldehyde, with the former being obtained on the basis of C2 building blocks, e.g. from ethylene and synthesis gas.
  • the slight yellowing of the monomers also increases slightly during longer storage, for example in a storage tank, or due to the transport time for further processing.
  • the slight yellowing of the monomers also leads to a yellowing of the downstream products, such as molding compounds or other polymers, for example Plexiglas-based granules and semi-finished products that are produced from MMA.
  • EP 36 76241 explicitly proposes adjusting the pH and the water content specifically during the oxidative esterification and treating the crude product of this stage further in another reactor, with the water content being higher and the pH being lower in the aftertreatment is than in the original reaction. Although this procedure has proven to be effective, it has also proven to be technically complex.
  • the product does not contain any (meth)acrylonitrile, but a relatively high proportion in the ppm range of methyl isobutyrate, which is also referred to as methyl isobutyrate.
  • the salary 6 typically fluctuates between 100 and 700 ppm.
  • Other characteristic traces are dimethoxyisobutene and dimethoxyisobutane.
  • (meth)acrylonitrile is usually contained in concentrations of 30 to 250 ppm.
  • Methyl propionate and methyl isobutyrate are also found, but in lower concentrations than in the C2-based methods.
  • Pentanones such as diethyl ketone or isopropyl methyl ketone and ethanol are not found or can only be found in the single-digit ppm range.
  • the C4-based processes in particular those that are carried out as gas-phase processes, have other specific traces. Traces of methyl isobutyrate and methyl propionate are also detected here, but dimethylfuran and pyruvic acid are particularly characteristic as trace components, which also have an influence on the yellowness index in the isolated monomer.
  • diactyl is a coloring component that has to be removed during the isolation process, but partially penetrates into the isolated MMA. In the case of commercially available MMA, levels between just over 0 and 10 ppm can be detected.
  • the object of the present invention was therefore to reduce the yellowness index of alkyl (meth)acrylates, in particular of MMA, in the simplest possible way.
  • a further object was that the reduction in yellowness should be sustained, i.e. even after long storage of the composition containing the alkyl (meth)acrylate.
  • a further object was to provide a monomeric product quality of the alkyl (meth)acrylate which has an improved yellowness index.
  • this improved optical product quality of the monomers should lead to improved optical properties with a reduced yellowness index in the poly(meth)acrylates thus produced, even after polymerization.
  • the method for sustainable yellow value reduction should be toxicologically harmless and simple and inexpensive to use.
  • aldehydes can be chosen relatively freely. According to the invention, aldehydes can be used which have an R radical of between 1 and 20 8th
  • R can be a linear, branched or cyclic alkyl group, an aromatic group, an ether group or a combination of several of these groups.
  • Examples of common linear alkyl groups are ethyl, propyl, n-butyl, n-hexyl or n-dodecyl groups.
  • Branched alkyl groups include those alkyl groups having one or more, for example, tertiary or quaternary carbon atoms. Examples of these are isopropyl, isobutyl or tertbutyl or ethylhexyl groups.
  • Cyclic alkyl groups can be, for example, cyclohexyl, cyclopentyl or methylcyclohexyl groups.
  • aromatic groups or combinations of aromatic and saturated alkyl groups can also be used.
  • aromatic groups are phenyl or benzyl groups.
  • radicals which contain a total of up to 20 carbon atoms and additional oxygen atoms in the form of one or more ether or hydroxyl groups.
  • Aldehydes which contain olefinic groups cannot be used according to the invention, since these are potentially active in polymerization. In addition, they do not seem to have any effect, as can be seen at different concentrations of residual methacrolein in C2 or C4 MMA.
  • heteroatoms such as nitrogen or sulfur heteroatoms in particular, are excluded in the aldehyde, since these can, for example, be subject to oxidation sensitivity and can in turn lead to discoloration.
  • Halogen atoms are again unsuitable for reasons of reactivity and from a toxicological point of view.
  • the aldehyde is particularly preferably acetaldehyde, propanal, 3-methylpentanal, iso- or n-butanal and n-pentanal.
  • the present process is particularly preferably used for adding additives to commercially available alkyl (meth)acrylates, such as methyl methacrylate (MMA).
  • alkyl (meth)acrylates such as methyl methacrylate (MMA).
  • MMA methyl methacrylate
  • other monomers such as, in particular, n- or tert-butyl methacrylate, ethylhexyl methacrylate, ethyl or propyl methacrylate can also be additized.
  • the process can also be used for acrylates, such as methyl or butyl acrylate.
  • the yellow values of important functional (meth)acrylates, such as methacrylic acid, hydroxyethyl or hydroxypropyl (meth)acrylate can also be reduced.
  • the alkyl (meth)acrylate is preferably methyl methacrylate. 9
  • the aldehyde between 0.5 and 500 ppm by weight of the aldehyde are added to the respective monomer composition.
  • the optimum amount depends on the (meth)acrylate to be added and the aldehyde used. This amount can be determined by a person skilled in the art for the respective combination with a few simple manual tests. For many of these combinations, a preferred amount of aldehyde added of between 1 and 250 ppm by weight, particularly preferably between 10 and 150 ppm by weight, has proven to be advantageous.
  • DMBP 2,4-dimethyl-6-tert-butylphenol
  • HQME hydroquinone, very particularly preferably hydroquinone methyl ether
  • the process according to the invention is preferably used in such a way that the alkyl (meth)acrylate has a yellowness value [D65/10] that is reduced by at least 10%, particularly preferably at least 15%, one hour after addition of the aldehyde.
  • the alkyl (meth)acrylate particularly preferably has a yellowness index [D65/10] that is reduced by at least 40%.
  • the yellow index of a (meth)acrylate alkyl ester can be reduced markedly within a short time not only by simply adding the aldehydes described. At least as surprisingly, it was found that this reduction in the yellow value is so lasting that it can still be detected to the same or at least a similar extent even after several days of storage. This is observed even after storage at elevated temperatures such as 40°C.
  • the process according to the invention is preferably used in such a way that the alkyl (meth)acrylate still has a yellowness index [D65/10] reduced by at least 10%, particularly preferably at least 15%, 8 days, preferably 1 month, after addition of the aldehyde.
  • a yellowness index [D65/10] reduced by at least 10%, particularly preferably at least 15%, 8 days, preferably 1 month, after addition of the aldehyde.
  • the yellowness index of polymers produced from alkyl (meth)acrylates with additives according to the invention is also significantly reduced compared to polymers produced analogously without the additives according to the invention. This effect is stable even when the polymers are stored for a long time, for example for a month. Even after weathering tests on the polymers, the color stabilization is easily measurable and surprisingly strong. 10
  • the process according to the invention can be used not only for reducing the yellowness index of pure alkyl (meth)acrylates such as MMA, but also of monomer mixtures consisting predominantly of different alkyl (meth)acrylates.
  • the aldehyde can be added to the monomer mixture or, alternatively, one or more aldehydes have already been added to an admixed monomer according to the invention in such a way that the entire mixture is obtained with an inventive concentration of the aldehyde.
  • Aromatic aldehydes such as benzaldehyde and 3-hydroxybenzaldehyde, also have an effect, albeit one that is initially reduced compared to aldehydes with pure alkyl groups. These can therefore be used according to the invention, but are less preferred.
  • compositions containing at least 97.5% by weight of an alkyl (meth)acrylate are also part of the present invention.
  • particularly preferred aldehydes are isobutanal, n-pentanal or 3-methylpentanal.
  • the alkyl (meth)acrylate is particularly preferably, but not restrictively, methyl methacrylate (MMA).
  • MMA methyl methacrylate
  • the composition preferably contains at least 99.5% by weight, ideally at least 99.9% by weight, of MMA. Further monomers which can be contained in the composition according to the invention have already been shown in the description of the method.
  • the composition preferably has at least 97.5% by weight of the alkyl (meth)acrylate and at least between 0.5 and 500 ppm by weight of the aldehyde.
  • the composition preferably contains 99.5% by weight, particularly preferably 99.8% by weight, of alkyl (meth)acrylate and between 1 and 300 ppm by weight, in particular between 20 and 250 ppm by weight and very particularly preferably between 10 and 130 ppm by weight , in particular between 30 and 90 ppm by weight of the aldehyde.
  • the aldehyde or aldehydes in the composition are particularly preferably methanal, acetaldehyde, propanal, iso- or n-butanal, pentanal, 2-methylpentanal, decanal, dodecanal or a mixture of at least two of these aldehydes.
  • composition according to the invention preferably additionally contains between 1 and 300 ppm by weight of a polymerization stabilizer.
  • a polymerization stabilizer are preferably 2,4-dimethyl-6-tert-butylphenol or a hydroquinone, very particularly preferably hydroquinone methyl ether (HQME).
  • the effect according to the invention is particularly pronounced in the case of MMA or other alkyl (meth)acrylates, which were produced using the C3-based ACH process, among other things.
  • this surprising effect is due in particular to the fact that the composition contains acrylonitrile and/or methacrylonitrile. It is particularly preferred if the total of less than 300 ppm by weight, in particular less than 200 ppm by weight, of acrylonitrile and methacrylonitrile is present in the composition.
  • the effect according to the invention is also particularly pronounced in the case of MMA or other alkyl (meth)acrylates, which were produced, inter alia, by means of a C2-based process.
  • this surprising effect is due in particular to the fact that the composition contains at least two components selected from n-butanol, tert-butanol, methyl acrylate, methyl isobutyrate, methyl propionate, 1,1-dimethoxyisobutene and ethyl methacrylate, especially if the composition contains n-butanol, tert-butanol, methyl acrylate, methyl propionate and ethyl methacrylate.
  • n-butanol, tert-butanol, methyl acrylate, methyl propionate and ethyl methacrylate are present in the composition. It is just as preferred if the total amount of n-butanol, tert-butanol, methyl isobutyrate, methyl acrylate, methyl propionate and ethyl methacrylate is less than 700 ppm by weight.
  • this surprising effect is due in particular to the fact that the composition contains dimethylfuran, methyl pyruvate and/or diacetyl, preferably all three components. It is particularly preferred if the sum total of these three components is less than 30 ppm by weight, in particular less than 10 ppm by weight, in the composition.
  • Figure 1 compares the results of Examples 1 to 12 in relation to Comparative Examples VB1, 2 and 3 with regard to stabilization of C2, C3 or C4 MMA with different concentrations of isobutanal (see also Results in Table 1).
  • methyl methacrylate was doped with an aldehyde such as isobutanal.
  • This procedure initially relates to Examples 1 to 12. Subsequently or at the specified times, the yellowness value Y.1. D65/10° determined according to DIN 6167. The following raw materials were used to produce the doped methyl methacrylate samples:
  • C3-MMA Methyl methacrylate from a Rohm C3 process, manufactured using the ACH process
  • Methyl methacrylate from a Rohm C4 process produced from isobutene which had already been stabilized with 50 ppm hydroquinone monomethyl ether (hereinafter C4-MMA) 13 isobutanal from Merck KGaA
  • methyl methacrylate was placed in a glass beaker, the hydroquinone monomethyl ether stabilizer was dissolved therein if required, and isobutanal was added. The mixture was homogenized with a magnetic stirrer for one hour. The yellow value was then determined to assess the optical quality.
  • the yellowness value was determined at the start of storage at 50°C and after a storage time of 4 weeks and 8 weeks at a corresponding storage temperature of 50°C. 16
  • Comparative example CE4 (reference example for yellow value after storage):

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
EP22727014.7A 2021-05-10 2022-04-29 Ungesättigte ester, enthaltend ein additiv zur reduktion und stabilisierung des gelbwertes Pending EP4337633A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP21172931 2021-05-10
PCT/EP2022/061442 WO2022238144A1 (de) 2021-05-10 2022-04-29 Ungesättigte ester, enthaltend ein additiv zur reduktion und stabilisierung des gelbwertes

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EP4337633A1 true EP4337633A1 (de) 2024-03-20

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EP22727014.7A Pending EP4337633A1 (de) 2021-05-10 2022-04-29 Ungesättigte ester, enthaltend ein additiv zur reduktion und stabilisierung des gelbwertes

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Country Link
EP (1) EP4337633A1 (ko)
JP (1) JP2024518080A (ko)
KR (1) KR20240006654A (ko)
CN (1) CN117279885A (ko)
BR (1) BR112023023281A2 (ko)
TW (1) TW202311223A (ko)
WO (1) WO2022238144A1 (ko)

Family Cites Families (15)

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US2848499A (en) 1956-05-09 1958-08-19 Celanese Corp Preparation of unsaturated aldehydes
DE3106557A1 (de) 1981-02-21 1982-09-16 Basf Ag, 6700 Ludwigshafen Verfahren zur herstellung von (alpha)-alkylacroleinen
JPS606635A (ja) * 1983-06-24 1985-01-14 Mitsubishi Petrochem Co Ltd １，２−不飽和カルボン酸および／またはそのエステルの精製法
DE3740293A1 (de) 1987-11-27 1989-06-01 Hoechst Ag Verfahren zur herstellung von alpha-alkylacroleinen
JP3069420B2 (ja) 1991-11-05 2000-07-24 ダイセル化学工業株式会社 反応器および反応方法
US5468899A (en) * 1995-01-11 1995-11-21 Bauer, Jr.; William Process for purifying α,β-unsaturated esters
SG71815A1 (en) 1997-07-08 2000-04-18 Asahi Chemical Ind Method of producing methyl methacrylate
DE10144490A1 (de) * 2001-09-10 2003-03-27 Basf Ag Verfahren zur Herstellung von (Meth)acrylsäureestern
AU2002354236A1 (en) 2001-12-21 2003-07-09 Asahi Kasei Chemicals Corporation Oxide catalyst composition
JP4173757B2 (ja) 2003-03-26 2008-10-29 ジヤトコ株式会社 ロックアップクラッチの寿命判定方法及びスリップロックアップ領域設定方法並びに寿命判定装置
US7141702B2 (en) 2004-03-26 2006-11-28 Council Of Scientific And Industrial Research Process for the synthesis of α-substituted acroleins
RU2523228C2 (ru) * 2008-12-18 2014-07-20 ЛУСАЙТ ИНТЕРНЭШНЛ ЮКей ЛИМИТЕД Способ очистки метилметакрилата
KR102213622B1 (ko) 2013-04-19 2021-02-08 룀 게엠베하 메틸메타크릴레이트의 제조 방법
TWI715627B (zh) 2015-09-16 2021-01-11 德商羅伊姆公司 含鈉鹽之mma-甲醇混合物的萃取後處理
EP3450422A1 (de) 2017-08-29 2019-03-06 Evonik Röhm GmbH Verfahren zur herstellung optischer formmassen

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TW202311223A (zh) 2023-03-16
KR20240006654A (ko) 2024-01-15
BR112023023281A2 (pt) 2024-01-23
WO2022238144A1 (de) 2022-11-17
CN117279885A (zh) 2023-12-22
JP2024518080A (ja) 2024-04-24

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