Process for the manufacture of (meth)acrylates comprising an adsorption step

Abstract

The present invention relates to a process for the preparation of C1 to C 22 - (meth)acrylates, comprising an adsorption step, wherein a product mixture (2) comprising C1 to C 22 - (meth)acrylates and phenothiazine (PTZ) is contacted with an adsorption material (6) and a product composition (8) is obtained. The present invention further relates to polymers based on the product composition.

Description

Technical Field

[0001] The present invention relates to a method for preparing (meth)acrylates, the method comprising an adsorption step wherein a product mixture containing (meth)acrylates is contacted with an adsorbent material to obtain a product composition. Background Technology

[0002] (Meth)acrylates, also known as (meth)acrylates, can be prepared, for example, by esterification of (meth)acrylic acid with an alcohol or olefin, or by (meth)acrylic anhydride and an alcohol in the presence of an esterification catalyst. Such methods can be found, for example, in the article "Acrylic Acid and Its Derivatives" in the Kirk-Othmer Encyclopedia of Chemical Technology (Wiley, 2002) (https: / / doi.org / 10.1002 / 0471238961.0103182502012105.a01.pub2) and in the article "Methacrylic Acid and Its Derivatives" in the Kirk-Othmer Encyclopedia of Chemical Technology (Wiley, 2003) (https: / / doi.org / 10.1002 / 0471238961.1305200807181519.a01.pub2).

[0003] In addition, (meth)acrylates can be prepared by transesterification of reactant (meth)acrylates (also known as starting (meth)acrylates) with alcohols.

[0004] Polymers and copolymers in bulk polymer or polymer dispersion form based on (meth)acrylates are of great significance and are used, for example, as adhesives, varnishes, paints, textile, leather and paper additives, ink compositions, resist compositions for photolithography processes, and active compositions for 3D printing processes.

[0005] Polymerizable compounds such as (meth)acrylates are known to readily polymerize, for example, through thermal, light, or peroxide reactions. Polymer formation results in equipment contamination, pipe and pump blockages, and scaling on trays or internal components and heat exchanger surfaces. Cleaning the facility is a complex and expensive process due to factors such as downtime, and pollutes the environment due to wastewater generated during cleaning. Productivity and equipment availability (uptime) are also consequently reduced.

[0006] Typically, the polymerization of (meth)acrylates is inhibited using polymerization inhibitors as described, for example, in EP2197827B1 and DE102004003733A1. In some cases, combinations of different polymerization inhibitors are applied at different steps of the manufacturing process. For example, phenothiazine (PTZ) is present as a polymerization inhibitor in the conversion and purification steps, but is usually replaced by another polymerization inhibitor in the target product, particularly for storage purposes. To replace PTZ, it is usually separated from the product mixture by at least one distillation step, and another polymerization inhibitor is added to the target product. However, removal of PTZ from the product may be insufficient, and the remaining PTZ may have adverse effects, such as staining when using the manufactured (meth)acrylate, for example, during the formation of polymers based on (meth)acrylate monomers.

[0007] (Meth)acrylate monomers can be used as monomers or comonomers in radical, cationic, anionic, and / or complex-catalyzed polymerizations. (Meth)acrylates are suitable for any type of polymerization, such as emulsion polymerization, solvent-based polymerization, or bulk polymerization. Curable compositions containing (meth)acrylates can be applied to organic solvent-based, water-based, and solvent-free systems, such as 100% curable compositions. A 100% curable composition is a composition that substantially contains no water or organic solvents. 100% curable compositions typically contain oligomers or polymers that can be cured by radical polymerization and a radical initiator.

[0008] Important applications of (meth)acrylate monomers include, for example, decorative or technical coatings in industrial applications, as well as adhesives, sealants, paper chemicals such as adhesives and sizing agents, leather and textile chemicals such as adhesives and hydrophobic agents, rheology modifiers, impact modifiers for plastics, pour point depressants for oils and lubricants, and reactive diluents for printing inks or UV-curable resins and systems. Furthermore, radiation-curable compositions containing (meth)acrylate monomers can be used as coatings, printing inks, photoresists, adhesives, and in additive manufacturing.

[0009] Typically, (meth)acrylates are prepared by a method comprising the following steps: an esterification step of esterifying (meth)acrylate with a feed alcohol to obtain crude (meth)acrylate, and a purification step of purifying the crude (meth)acrylate to obtain the target product. To prevent polymerization of (meth)acrylates during production, high-boiling polymerization inhibitors are metered at one or more nodes of the production equipment. In the purification step, a distillation column is applied to remove byproducts and / or recycle valuable substances from the product stream. WO2025 / 131961A1 relates to exemplary distillation equipment. To achieve high product purity and remove unwanted polymerization inhibitors from the gaseous target product, the distillation column is typically equipped with, for example, an external droplet separator, such as a centrifugal droplet separator or demister as described in DE19604253A1.

[0010] Known methods for preparing, for example, 2-ethylhexyl acrylate (2-EHA) are based on esterification with 2-ethylhexanol in the presence of a catalyst and usually at least one polymerization inhibitor. Such methods are disclosed, for example, in DE19604253A1. The manufacture of methyl acrylate, ethyl acrylate, and butyl (meth)acrylate, such as n-butyl acrylate and / or tert-butyl (meth)acrylate, is proposed, for example, in WO2003 / 022793A1, DE19935453A1, and WO2016 / 156410A1.

[0011] Due to the manufacturing process, polymerization inhibitors may be present in the product (meth)acrylate, and / or polymerization inhibitors may be added to the resulting (meth)acrylate.

[0012] WO1992 / 06799A1 discusses the suppression of polymerization of methacrylate and acrylate monomers on a surface by using a water-based coating containing phenothiazine. An acrylic copolymer with a phenothiazine volume concentration of approximately 70% was used.

[0013] However, in later stages of the manufacturing process of acrylic acid and other monomers, it may be desirable to further purify the target product and remove polymerization inhibitors applied during manufacturing. This removal can be achieved, for example, by distillation, but this is very complex because the monomers must be converted to a gaseous state. Furthermore, adsorption may be considered for specific applications, where selecting the appropriate adsorbent for the specific target product to achieve efficient operation is highly challenging.

[0014] JP2017-206452A describes a method for removing polymerization inhibitors of vinyl monomers by adsorption.

[0015] EP4524126A1 discloses a method for treating (meth)acrylates, particularly cyanoacrylate materials, with clay, wherein the clay is acid-activated montmorillonite.

[0016] CN114832789A proposes the adsorption of polymerization inhibitors from acrylic acid using bentonite as an adsorbent. WO2004 / 052819A2 and WO2010 / 142546A2 also focus on the purification of acrylic acid by adsorption, while EP3736262A1 relates to the purification of acrylamide. Summary of the Invention

[0017] The object of this invention is to provide a method that provides a significant reduction in PTZ content in C1 to C2. 22 -(meth)acrylate. Furthermore, an object of the present invention is to provide a composition suitable for forming polymers with reinforcing properties.

[0018] This objective is achieved through a method for preparing C1 to C2. 22 A method for producing (meth)acrylates, comprising an adsorption step wherein C1 to C2 is formed. 22 A mixture of (meth)acrylate and phenothiazine (PTZ) products is contacted with an adsorbent material to obtain a product composition.

[0019] This objective is further achieved by a product composition obtainable by the method used for preparation, which, relative to the total product composition, comprises at least 95.0% by weight, preferably at least 98.0% by weight, more preferably at least 98.5% by weight, even more preferably at least 99.0% by weight, even more preferably at least 99.5% by weight, even more preferably at least 99.7% by weight of C1 to C2. 22 -(meth)acrylate and 1.0 wt ppm or less, preferably less than 0.7 wt ppm, more preferably less than 0.5 wt ppm, even more preferably less than 0.2 wt ppm of phenothiazine, and optionally 2 wt ppm to 50 wt ppm of 4-methoxyphenol. Preferably, the product composition obtainable by this method of preparation has an acid value of less than 0.1 mg KOH / g relative to the total product composition.

[0020] Furthermore, the present invention relates to a polymer based on a product composition obtainable by the method used for preparation, wherein the polymer preferably contains at least 95.0% by weight, preferably at least 98.0% by weight, more preferably at least 98.5% by weight, even more preferably at least 99.0% by weight, even more preferably at least 99.5% by weight, even more preferably at least 99.7% by weight of C1 to C2, relative to the total product composition. 22 - (meth)acrylate and 1 wt ppm or less of phenothiazine, and optionally 2 wt ppm to 50 wt ppm of 4-methoxyphenol.

[0021] The present invention also relates to a method for preparing a polymer, comprising the steps of: polymerizing a polymer capable of producing a product composition by means of emulsion polymerization in an aqueous reaction medium, by means of solution polymerization, by means of suspension polymerization, or by means of bulk polymerization, particularly by means of bulk polymerization, wherein the polymer preferably contains at least 95.0% by weight, preferably at least 98.0% by weight, more preferably at least 98.5% by weight, even more preferably at least 99.0% by weight, even more preferably at least 99.5% by weight, even more preferably at least 99.7% by weight of C1 to C2, relative to the total product composition. 22 - (meth)acrylate and 1 wt ppm or less of phenothiazine, and optionally 2 wt ppm to 50 wt ppm of 4-methoxyphenol; also relates to the use of the product composition in the preparation of adhesives and / or coatings, particularly adhesives and / or coatings capable of UV curing. Attached Figure Description

[0022] Figure 1 It is used to manufacture C1 to C 22 A schematic diagram of the equipment and methods for producing (meth)acrylates. Detailed Implementation

[0023] Due to the adsorption step of the method of the present invention, C1 to C2 compounds with very low PTZ content or essentially no PTZ are provided. 22 -(meth)acrylate products. Based on the C1 to C1... 22 Based on (meth)acrylate product compositions, polymers and products containing these polymers, such as adhesives and / or coatings, can be obtained with high quality, particularly in terms of optical properties. Undesirable staining or discoloration during polymer formation in downstream manufacturing processes is avoided.

[0024] Preferably, the method for manufacturing further includes the following steps: - A conversion step in which alcohols or olefins and (meth)acrylic acid compounds, particularly (meth)acrylic acid, are converted to C1 to C2 compounds in the presence of a catalyst. 22 -(meth)acrylate, and obtain C1 to C2 acrylates. 22 A crude mixture of (meth)acrylates, - Purification step, wherein the crude mixture is subjected to at least one distillation stage to obtain a product mixture.

[0025] (Meth)acrylic acid compounds are preferably selected from reactant (meth)acrylates (also known as starting (meth)acrylates) and (meth)acrylic acid. The reactant (meth)acrylates differ from C1 to C2. 22(Meth)acrylates, and are particularly suitable for transesterification. More preferably, (meth)acrylate compounds are (meth)acrylic acid, especially acrylic acid.

[0026] Preferably, based on the total product mixture, the product mixture contains at least 95.0% by weight, preferably at least 98.0% by weight, more preferably at least 98.5% by weight, even more preferably at least 99.0% by weight, even more preferably at least 99.5% by weight, even more preferably at least 99.7% by weight of C1 to C2. 22 - (meth)acrylate.

[0027] Unless otherwise explicitly stated, the reported amount of a monomer is based on the sum of all monomers in 100 parts by weight or percentages.

[0028] (Meth)acrylate is an abbreviation for acrylate and / or methacrylate. For example, 2-ethylhexyl (meth)acrylate includes 2-ethylhexyl acrylate and / or 2-ethylhexyl methacrylate. (Meth)acrylate is an abbreviation for acrylic acid and / or methacrylic acid.

[0029] In a preferred embodiment, the method includes at least a conversion step and at least one or at least two purification steps, but may typically include additional steps such as a catalyst removal step and a (meth)acrylic acid separation step. The purification step, or at least one purification step, is particularly carried out upstream of the adsorption step. More preferably, the conversion step and the purification step, or at least one purification step, are carried out upstream of the adsorption step. Typically, the conversion step is carried out upstream of the purification step, or at least one purification step. Specifically, one of the at least two purification steps is carried out in a first distillation column, and the other of the at least two purification steps is carried out in a second distillation column.

[0030] C1 to C 22 - (Meth)acrylates are preferably formed from (meth)acrylic acid and an alcohol. (Meth)acrylic acid is preferably acrylic acid. (Meth)acrylic acid can be synthesized by known methods. For example, the (meth)acrylic acid used can be obtained by the direct oxidation of propane, propylene, and acrolein, or isobutane, isobutene, and methacrolein. Crude (meth)acrylic acid can be purified by multi-stage crystallization, or, if necessary, by chemical treatment with an aldehyde scavenger and distillation. Crude, pure, or purified (meth)acrylic acid is generally stabilized with a polymerization inhibitor or a mixture of polymerization inhibitors to prevent premature polymerization of (meth)acrylic acid.

[0031] In the conversion step, alcohols containing 1 to 8 carbon atoms are preferably used, such as C1 to C8 alkanols, including methanol, ethanol, 2-ethylhexanol, tert-butanol, n-butanol, isobutanol, and 2-octanol. The alcohol is preferably methanol, ethanol, 2-ethylhexanol, tert-butanol, n-butanol, or isobutanol, more preferably 2-ethylhexanol, n-butanol, or isobutanol, especially 2-ethylhexanol.

[0032] C1 to C 22 - (meth)acrylate is preferably (meth)acrylate C1 to C1. 22 -Alkyl ester. Term C n To C m -alkyl represents a group having a straight-chain, branched, or cyclic saturated hydrocarbon group having n to m carbon atoms, where n and m are integers. Preferably, C1 to C2 are alkyl groups. 22 -(meth)acrylates are C1 to C8-(meth)acrylates, more preferably C4 to C8-(meth)acrylates, and even more preferably C4 to C8-acrylates. Specifically, C1 to C8... 22 - (Meth)acrylates are 2-ethylhexyl (meth)acrylates, such as 2-ethylhexyl acrylate; methyl acrylate, ethyl acrylate and / or butyl (meth)acrylate (such as n-butyl acrylate and / or tert-butyl (meth)acrylate), especially 2-ethylhexyl acrylate.

[0033] The molar ratio of (meth)acrylic acid to alcohol in the reaction mixture is typically in the range of 0.7 to 2.0, preferably in the range of 0.7 to 1.7, and particularly preferably in the range of 0.7 to 1.3. Generally, (meth)acrylic acid is used in a deficient amount based on the amount of alcohol used. For example, the molar ratio of (meth)acrylic acid to alcohol in the reaction mixture to be converted is in the range of 0.900 to 0.998, preferably in the range of 0.975 to 0.995.

[0034] The conversion is typically carried out in the presence of a catalyst. Acid catalysts, particularly strong acid catalysts, are preferred. Preferably, the catalyst is an inorganic acid or sulfonic acid, and in particular, the catalyst is selected from the group consisting of: sulfuric acid; phosphoric acid; alkyl sulfonic acids, such as methanesulfonic acid or trifluoromethanesulfonic acid; aryl sulfonic acids, such as benzenesulfonic acid, p-toluenesulfonic acid (pTSA), m-toluenesulfonic acid, o-toluenesulfonic acid, or dodecylbenzenesulfonic acid; and mixtures thereof. Specifically, the catalyst is sulfuric acid or pTSA. Based on the reaction mixture, the catalyst content is typically from 0.1% to 10.0% by weight, preferably from 0.3% to 5.0% by weight.

[0035] The conversion is preferably carried out at a conversion temperature in the range of 70°C to 150°C, more preferably in the range of 80°C to 130°C. Furthermore, the conversion is preferably carried out at a total conversion pressure in the range of 100 hPa to 1020 hPa, more preferably in the range of 200 hPa to 800 hPa, and even more preferably in the range of 250 hPa to 700 hPa. The conversion can take place in one or more reaction zones. In the case of more than one reaction zone, the conversion temperature is preferably set in such a cascade manner that it increases sequentially.

[0036] The reactants, namely (meth)acrylic acid and alcohol, preferably have a residence time of 1 to 20 hours, more preferably 2 to 8 hours, during the conversion. Residence time should be understood to mean the time that a volume drawn from the bottom of at least one reactor remains in the liquid volume.

[0037] Heat can be supplied to the converter and at least one reactor via conventionally designed internal and / or external heat exchangers and / or via jacket heating, respectively. Steam is the commonly used heat transfer medium. Heat is preferably supplied via an external circulating evaporator with natural or forced circulation. Complete mixing of the reaction mixture is preferably carried out in a known manner, such as by stirring, pumping circulation, or natural circulation.

[0038] The conversion is preferably carried out in at least one reactor. This at least one reactor can be a vessel, a tower, or a combination thereof. Preferably, the conversion is carried out in a reaction zone comprising one or more reaction zones (e.g., a reactor cascade of two to four, preferably two to three reactors). In embodiments of the invention having multiple reaction zones, cascading these reaction zones is advantageous. If more than one reaction zone is generated within the same reactor (e.g., by using separate metal sheets), the number of reaction zones can also be greater than four.

[0039] The conversion is preferably carried out in the presence of PTZ and optionally another polymerization inhibitor.

[0040] The at least one reactor may be equipped with a distillation unit. In this case, it is preferable to allow reflux from the distillation unit to enter the first of the at least one reactor. The distillation unit typically includes internal separation components such as trays, stacked packing, and / or packed packing. Among the trays, bubble cap trays, sieve trays, valve trays, Soman trays, and / or dual-flow trays are preferred; among the packed packing, those including ring packing, spiral packing, saddle packing, Raschig rings, Intos rings or Pall rings, barrel saddle packing or Intalox saddle packing, Top-Pak, etc., or braided packing are preferred. The distillation unit preferably includes 5 to 20 theoretical trays.

[0041] In a preferred embodiment, the water formed during the conversion process, along with low-boiling components such as acetaldehyde, acrolein, water, acetic acid, and / or propionic acid, and / or with a solvent that forms an azeotrope with water and has a boiling point of up to 130°C at a pressure of 0.1 MPa, is preferably condensed in a condenser of known design. It is preferable not to use external solvents.

[0042] Within the framework of this invention, relative to C1 to C 22 - (meth)acrylate, the low-boiling component is the component with a boiling point below C1 to C2 at 0.1 MPa (1 bar). 22 Substances with boiling points of (meth)acrylates. Within the framework of this invention, relative to C1 to C2. 22 - (meth)acrylate, the high-boiling component has a boiling point above C1 to C2 at 0.1 MPa (1 bar). 22 - (meth)acrylates are substances with high boiling points.

[0043] In one embodiment, the conversion is carried out in at least one reactor under conditions in the presence of an inherent azeotropic entrainer, particularly at C1 to C2. 22 In the case of (meth)acrylate being 2-ethylhexyl acrylate, the azeotropic entrainer is preferably an olefin compound, typically an olefin having the same number of carbons as the alcohol. During the conversion process, these olefins are inherently generated at low rates in the dehydration side reaction and possibly subsequent isomerization of the alcohol. In the case of 2-ethylhexanol, the olefin byproduct is typically octene, such as 2-ethylhex-1-ene, 3-methylhept-2-ene, and 3-methylhept-3-ene. Generally, the azeotropic entrainer forms a low-boiling azeotrope with water, which entrains water and distills it to the top of the distillation unit.

[0044] The distillate from the distillation unit is preferably condensed in a condenser. Within the framework of this invention, the term "distillate" is defined as the product taken from the column as a byproduct or as the top product. The condensate preferably decomposes into an aqueous phase and an organic phase; the aqueous phase is generally discharged, and the organic phase particularly comprises C1 to C2. 22 - (meth)acrylates, more specifically, for example, olefinic entrainers, 2-ethylhexanol, 2-ethylhexyl acetate and 2-ethylhexyl propionate.

[0045] Polymerization inhibitors such as PTZ and optionally other polymerization inhibitors can be added to the condenser of the distillation unit. A polymerization inhibitor feed stream can be added to the distillation unit. Preferably, the polymerization inhibitor feed stream comprises a polymerization inhibitor (such as PTZ) and optionally other polymerization inhibitors, as well as a solvent or a mixture thereof. The solvent is preferably an alcohol and / or C1 to C2 alcohols. 22-(meth)acrylate. More preferably, the polymerization inhibitor stream contains 0.1% to 6.0% by weight, or even more preferably 0.5% to 3.0% by weight, of polymerization inhibitor, particularly phenothiazine and / or 4-methoxyphenol, relative to the total polymerization inhibitor stream. Typically, the C1 to C2 of the polymerization inhibitor is... 22 A solution of (meth)acrylate (e.g., 2-ethylhexyl acrylate) is sprayed into the condenser and / or added to the reflux entering the conversion.

[0046] Preferably, in the purification step, the crude mixture is purified in a first distillation column and a second distillation column. More preferably, at least a portion of the crude mixture is introduced into the first distillation column having a top, and the purified mixture is withdrawn from the top of the first distillation column, the purified mixture containing at least 80% by weight of C1 to C2 based on the total purified mixture. 22 - (meth)acrylates, especially at least 85% by weight of C1 to C2. 22 - (meth)acrylate, and PTZ. Preferably, at least a portion of the purified mixture is introduced into the second distillation column via a side feed inlet. In particular, the product mixture is removed from the second distillation column via a side outlet or a bottom outlet.

[0047] Generally, the pressure measured at the top of the first distillation column is in the range of 40 hPa to 1500 hPa, preferably 50 hPa to 1100 hPa. The temperature measured at the bottom of the first distillation column is preferably in the range of 80°C to 180°C, more preferably 100°C to 150°C. The pressure measured at the top of the second distillation column is typically 40 hPa to 200 hPa. The temperature measured at the bottom of the second distillation column is preferably in the range of 120°C to 180°C.

[0048] At least a portion of the crude mixture can be directed directly or indirectly from at least one reactor to a first distillation column. Additional separation units, such as the additional columns outlined above, may be arranged between at least one reactor and the first distillation column, or between the first distillation column and a second distillation column. Specifically, the first distillation column is arranged downstream of at least one reactor, and the second distillation column is arranged downstream of the first distillation column. Preferably, at least a portion of the crude mixture is withdrawn from the top of the first distillation column. Downstream should be understood as the flow direction of the target product stream, typically associated with C1 to C2. 22 - Increased content of (meth)acrylates. Upstream is understood as flowing in the opposite direction to the target product stream.

[0049] At least a portion of the purified mixture can be directed from the first distillation column to the second distillation column, either directly or indirectly. Additional separation units, such as one or more extraction columns or one or more additional distillation columns, can be arranged between the first and second distillation columns. For example, a (meth)acrylic acid removal column can be located between the first and second distillation columns.

[0050] Preferably, at least a portion, more preferably a portion, of the crude mixture is introduced into a first distillation column. The first distillation column may be referred to as a heavy distillation column. The bottom of the first distillation column may be connected to a high-boiling compound treatment unit. In another embodiment, the first distillation column may be used as a catalyst removal column. In a particularly preferred embodiment, crude (meth)acrylate is introduced into the first distillation column. The at least portion of the crude mixture introduced into the first distillation column typically contains C1 to C2. 22 - (meth)acrylates, unreacted alcohols, acetates, and low-boiling components. When the starting alcohol is 2-ethylhexanol, the low-boiling components specifically include 2-ethylhexanol, 2-ethylhexyl acetate, and 2-ethylhexyl propionate.

[0051] At least a portion of the crude mixture may be fed to the bottom of the first distillation column or to a side inlet of the first distillation column. The first distillation column may include separating internal components such as trays, structured packing elements, and / or random packing elements. Preferably, the first distillation column includes, particularly in total, packing or 6 to 35 trays. In a preferred embodiment, the first distillation column includes 5 to 10 trays. In another preferred embodiment, the first distillation column includes 25 to 35 trays. Preferably, at least a portion of the crude mixture is fed to the bottom of the first distillation column, thus below the lowest separating internal components. During distillation in the first distillation column, particularly when the (meth)acrylate is n-butyl (meth)acrylate or isobutyl (meth)acrylate, an azeotrope may be formed. In particular, the azeotrope comprises or purifies the mixture and is withdrawn from the top of the first distillation column. In a preferred embodiment, the azeotrope is formed, for example, from n-butyl acrylate, water, and n-butanol.

[0052] Preferably, the second distillation column includes a side outlet and at least two trays as internal separation components, wherein in the second distillation column, a side feed inlet is arranged above the side outlet, and the side outlet is arranged between two of the at least two trays. In this arrangement, at least one tray is present or located below the side outlet. By providing at least one tray below the side outlet, product purity is further improved. Polymerization inhibitors, particularly PTZ, are prevented from being entrained from the bottom of the second distillation column into the side outlet. The at least one tray below the side outlet provides protection against PTZ and C1 to C2. 22The separation of (meth)acrylates allows the pure product to reach the side outlet with higher purity. In addition to the thermodynamic separation effect, at least one tray also acts as a barrier to droplets. More preferably, the second distillation column comprises at least three trays, and the side outlet is disposed above at least two of the at least three trays. Preferably, the second distillation column comprises, particularly in total, 10 to 60 trays, more preferably 20 to 55 trays. Typically, the second distillation column comprises a dual-flow tray and optionally at least one chimney tray. The side outlet may be disposed between two dual-flow trays. Preferably, the side outlet is disposed above two to five trays, for example, above three trays. More preferably, the side outlet is disposed at a theoretical tray in a region of the second distillation column that begins at one or more theoretical trays above the bottom theoretical tray and ends at 12 or fewer theoretical trays below the top theoretical tray, for example, at the third theoretical tray counting from the bottom theoretical tray. The side feed inlets are preferably located at one of the theoretical plates in the region of the second distillation column that starts above the bottom theoretical plate (three or more theoretical plates) and ends at the top theoretical plate (eight or fewer theoretical plates), for example, at the fourth theoretical plate counting from the bottom theoretical plate.

[0053] In a preferred embodiment, the method includes a catalyst removal step. Preferably, the crude mixture from the conversion, which typically contains C1 to C2, is removed. 22 - (meth)acrylates, unconverted alcohols, (meth)acrylic acid, low-boiling components, acetates, polymerization inhibitors such as PTZ, catalysts, and high-boiling components such as oxyesters are fed into a catalyst separation column, where the crude mixture is separated into bottom and top fractions.

[0054] The overhead fraction is preferably condensed and typically contains (meth)acrylates and low-boiling components. A portion, preferably 3% to 10% by volume, of the overhead fraction may be returned as reflux to the catalyst separation column. Polymerization inhibitors such as PTZ may be added to at least a portion of the overhead fraction.

[0055] At least a portion of the crude mixture, preferably at least a portion of the overhead fraction, can be fed into the (meth)acrylic acid separation step.

[0056] The bottom fraction of a catalyst separator typically contains catalyst, polymerization inhibitors such as PTZ, and C1 to C2. 22 - (meth)acrylates and high-boiling components. To recover valuable substances contained in the bottom fraction, it can be returned in whole or in part to the conversion process, preferably to the first reactor if a cascade is used, and / or fed to any remaining residue distillation and / or residue cracking. Preferably, 1% to 30% by volume of the bottom fraction is fed to residue cracking.

[0057] The catalyst separation column may include internal separation components and / or one or more droplet precipitators such as spray precipitators, and is typically equipped with a circulating evaporator and a condenser. The feed is preferably introduced into the bottom region of the catalyst separation column. The bottom temperature of the catalyst separation column is preferably in the range of 130°C to 160°C, and the top pressure is preferably in the range of 50 hPa to 200 hPa. The first distillation column may be a catalyst removal column.

[0058] Furthermore, the method may include a (meth)acrylic acid removal step, particularly before introducing at least a portion, preferably a portion, of the purified mixture into a second distillation column, especially upstream of the second distillation column. Additionally, the optional (meth)acrylic acid removal step preferably occurs after introducing at least a portion, preferably a portion, of the crude mixture into the first distillation column, particularly downstream of the first distillation column. In a preferred embodiment, a (meth)acrylic acid removal column is disposed between the first and second distillation columns. In another embodiment, the (meth)acrylic acid removal column may be part of the first distillation column.

[0059] The overhead fraction from the first distillation column, particularly the catalyst removal column, can be fed into the (meth)acrylic acid removal column and separated into a bottom stream and an overhead stream. The bottom stream is preferably substantially free of (meth)acrylic acid relative to the total bottom stream, particularly with a (meth)acrylic acid content of less than 0.1% by weight. 22 - (meth)acrylates, especially those containing more than 90% by weight of C1 to C2. 22 - (meth)acrylate. The bottom stream can also be referred to as crude (meth)acrylate. The top stream typically contains unreacted alcohols, C1 to C2 acrylates, and other components. 22 - (meth)acrylates, (meth)acrylic acid, and low-boiling components. The bottom temperature of the (meth)acrylic acid removal tower is typically in the range of 130°C to 160°C, and the top pressure of the (meth)acrylic acid removal tower is typically in the range of 50 hPa to 130 hPa.

[0060] The (meth)acrylic acid removal column may include internal separation components, particularly trays. Preferably, the (meth)acrylic acid removal column includes 20 to 40 theoretical trays. Preferably, the overhead fraction from the catalyst removal column is fed into the upper part of the (meth)acrylic acid removal column.

[0061] The bottom stream can be partially, preferably 10% to 20% by volume, returned as reflux to the (meth)acrylic acid removal tower. A portion of the bottom stream can be recycled back to the conversion process.

[0062] In a preferred embodiment, a polymerization inhibitor, such as PTZ, is fed into the condenser of a (meth)acrylic acid removal tower. A polymerization inhibitor stream containing PTZ can be added to the (meth)acrylic acid removal tower. Preferably, the polymerization inhibitor stream comprises a polymerization inhibitor (such as PTZ) and a solvent or is composed of the same. The solvent is preferably an alcohol and / or C1 to C2 alcohols. 22 -(meth)acrylate. More preferably, the polymerization inhibitor stream contains 0.1% to 6.0% by weight, or even more preferably 0.5% to 3.0% by weight, of polymerization inhibitor, particularly phenothiazine and / or 4-methoxyphenol, relative to the total polymerization inhibitor stream. Typically, the C1 to C2 of the polymerization inhibitor is... 22 A solution of (meth)acrylate (e.g., 2-ethylhexyl acrylate) is sprayed into the condenser.

[0063] The crude mixture exiting the reactor, particularly the distillation unit, and / or the stream taken from the top of the second distillation column, can be fed into the acetate column. Specifically, in the acetate column, a fraction consisting primarily of alcohols is separated from the substantially acetate-containing stream. The substantially alcohol-containing stream is advantageously recycled, at least partially, to the conversion. The substantially acetate-containing stream is typically discharged.

[0064] The acetate is preferably concentrated in the distillate of the first distillation column and at the bottom of the acetate column. The feed to the acetate column preferably contains less than 10% by weight of C1 to C2 relative to the total feed to the acetate column. 22 -(meth)acrylate, more preferably less than 5% by weight of C1 to C2. 22 - (meth)acrylate. The acetate column may include internal separation components such as trays, random packing, or structured packing, more preferably structured packing. Preferably, the acetate column is operated at a temperature in the range of 70°C to 170°C, more preferably 80°C to 160°C, measured at the bottom of the acetate column. The pressure measured at the top of the acetate column is preferably in the range of 90 hPa to 1000 hPa, more preferably in the range of 100 hPa to 500 hPa, and even more preferably in the range of 200 hPa to 400 hPa.

[0065] Within the framework of this invention, the bottom is understood as part of a tower, located below all the separate internal components. The top is understood as part of a tower, located above all the separate internal components.

[0066] The conversion and / or purification steps are preferably carried out in the presence of a PTZ. The conversion and / or purification steps may be carried out in the presence of an additional polymerization inhibitor. This additional polymerization inhibitor differs from the PTZ. The additional polymerization inhibitor may be present in the product mixture and / or product composition. The additional polymerization inhibitor may be added to the product mixture and / or product composition. In a preferred embodiment, the additional polymerization inhibitor is added to the product composition, particularly after the adsorption step. More preferably, at least MeHQ is added to the product composition, particularly at least after the adsorption step, wherein, even more preferably, the concentration of MeHQ is adjusted to a range of 2 to 50 wt ppm relative to the total product composition, even more preferably 3 to 50 wt ppm, particularly 5 to 20 wt ppm.

[0067] Other suitable polymerization inhibitors that can act as stabilizers may be, for example, N-oxides (nitroyl or N-oxy radicals, i.e., compounds having at least one NO group), such as 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxy (HO-TEMPO or 4-HT), 4-oxo-2,2,6,6-tetramethylpiperidine-N-oxy, 4-acetoxy-2,2,6,6-tetramethylpiperidine-N-oxy, 2,2,6,6-tetramethylpiperidine-N-oxy, bis(1-oxy-2,2,6,6-tetramethylpiperidine-4-yl) sebacate, 4,4',4"-tris(2,2,6,6-tetramethylpiperidine-N-oxy) phosphite, or 3-oxo-2,2,5,5 -Tetramethylpyrrolidine-N-oxy; a mono- or polyphenol having one or more alkyl groups, such as alkylphenols, for example, ortho-, meta-, or para-cresol (methylphenol), 2-tert-butylphenol, 4-tert-butylphenol, 2,4-di-tert-butylphenol, 2-methyl-4-tert-butylphenol, 2-tert-butyl-4-methylphenol, 2,6-tert-butyl-4-methylphenol, 4-tert-butyl-2,6-dimethylphenol, or 6-tert-butyl-2,4-dimethylphenol; quinones, such as hydroquinone, hydroquinone monomethyl ether, 2-methylhydroquinone, or 2,5-di-tert-butylhydroquinone; hydroxyphenols, such as catechol (1,2-dihydroxybenzene) or benzoquinone; aminophenols, such as para-aminophenol; nitrosophenols, such as para-nitrosophenol; alkoxyphenols, such as 2 -Methoxyphenol (guaiacol, catechol monomethyl ether), 2-ethoxyphenol, 2-isopropoxyphenol, 4-methoxyphenol (hydroquinone monomethyl ether), mono- or di-tert-butyl-4-methoxyphenol; tocopherols, such as α-tocopherol, 2,3-dihydro-2,2-dimethyl-7-hydroxybenzofuran (2,2-dimethyl-7-hydroxycoumarin); aromatic amines, such as N,N-diphenylamine, N-nitrosodiphenylamine; phenylenediamines, such as N,N'-dialkyl-p-phenylenediamine, wherein the alkyl groups may be the same or different and each independently consists of 1 to 4 carbon atoms, and may be straight-chain or branched, such as N,N'-dimethyl-p-phenylenediamine or N,N'-diethyl-p-phenylenediamine. Hydroxylamine, such as N,N-diethylhydroxylamine; imine, such as methyl ethylimine or methylene violet; sulfonamide, such as N-methyl-4-toluenesulfonamide or N-tert-butyl-4-toluenesulfonamide; oxime, such as aldehyde oxime, ketoxime or amidoxime, such as diethyl ketoxime, methyl ethyl ketoxime or salicylaldehyde oxime; phosphorus-containing compounds, such as triphenylphosphine, triphenyl phosphite, triethyl phosphite, hypophosphite or alkyl esters of phosphorite; sulfur-containing compounds, such as diphenyl sulfide; metal salts, such as copper or manganese, cerium, nickel and chromium salts, such as chlorides, sulfates, salicylates, toluenesulfonates, acrylates or acetates, such as copper acetate, copper(II) chloride, copper salicylate, cerium(III) acetate or cerium(III) ethylhexanoate, or mixtures thereof.

[0068] Preferably, at least one compound selected from hydroquinone, hydroquinone monomethyl ether, 4-hydroxy-2,2,6,6-tetramethylpiperidin-N-oxy, 4-oxo-2,2,6,6-tetramethylpiperidin-N-oxy, bis(1-oxy-2,2,6,6-tetramethylpiperidin-4-yl) sebacate, 4-methoxyphenol (MeHQ), 2-tert-butylphenol, 4-tert-butylphenol, 2,4-di-tert-butylphenol, 2-tert-butyl-4-methylphenol, 6-tert-butyl-2,4-dimethylphenol, 2,6-di-tert-butyl-4-methylphenol, 2-methyl-4-tert-butylphenol, hypophosphite, copper acetate (II), copper chloride (I), copper chloride (II), copper salicylate (II), and cerium acetate (III) is used as an additional polymerization inhibitor or a mixture of polymerization inhibitors. In a preferred embodiment, the additional polymerization inhibitor is selected from the group consisting of: hydroquinone, hydroquinone monomethyl ether, 4-methoxyphenol, 2-tert-butylphenol, 4-tert-butylphenol, 2,4-di-tert-butylphenol, 2-tert-butyl-4-methylphenol, 6-tert-butyl-2,4-dimethylphenol, 2,6-di-tert-butyl-4-methylphenol, 2-methyl-4-tert-butylphenol, hypophosphite, copper acetate (II), copper chloride (I), copper chloride (II), copper salicylate (II), and cerium acetate (III); and mixtures thereof. MeHQ is particularly preferred as an additional polymerization inhibitor.

[0069] In a preferred embodiment, PTZ and optionally additional polymerization inhibitors are added to the first and / or second distillation columns. More preferably, PTZ and optionally additional polymerization inhibitors enter the first and / or second distillation columns at the top of the respective columns. Even more preferably, PTZ and optionally additional polymerization inhibitors are fed into the condensers of the first and / or second distillation columns. Preferably, PTZ and optionally additional polymerization inhibitors are present in a solvent. The solvent is preferably an alcohol and / or C1 to C2 alcohols. 22-(meth)acrylate. More preferably, the concentration of PTZ and optional additional polymerization inhibitors, particularly PTZ and / or 4-methoxyphenol, is in the range of 0.1 wt% to 6.0 wt%, or even more preferably 0.5 wt% to 3.0 wt%, relative to the total polymerization inhibitor feed stream including the solvent. For example, the polymerization inhibitor feed stream added to the first distillation column may contain 0.10 wt% to 4.00 wt%, particularly 0.10 wt% to 2.00 wt% of PTZ, relative to the total polymerization inhibitor feed stream added to the second distillation column. The polymerization inhibitor feed stream added to the second distillation column may contain, for example, 0.05 wt% to 3.00 wt%, particularly 0.05 wt% to 2.00 wt%, more preferably 0.05 wt% to 1.50 wt%, or even more preferably 0.05 wt% to 1.00 wt% of PTZ and / or 4-methoxyphenol, particularly PTZ, relative to the total polymerization inhibitor feed stream including the solvent. In a preferred embodiment, the total amount of PTZ added to the second distillation column is less than the total amount of PTZ added to the first distillation column, more preferably 0.8 times or less, even more preferably 0.6 times or less, for example 0.5 times.

[0070] At least a portion of the purified mixture preferably enters the second distillation column in liquid form. Preferably, the purified mixture entering the second distillation column contains at least 5% by weight of alcohol, more preferably 5% to 15% by weight of alcohol, relative to the total purified mixture entering the second distillation column. The purified mixture entering the second distillation column contains at least 10 ppm by weight of PTZ, relative to the total purified mixture entering the second distillation column. More preferably, the purified mixture entering the second distillation column contains 10 ppm by weight to 500 ppm by weight, even more preferably 10 ppm by weight to 100 ppm by weight of PTZ, relative to the total purified mixture entering the second distillation column.

[0071] The product mixture can be directed through an additional gas-liquid separator upstream of the adsorption step and typically downstream of the purification step (e.g., downstream of the second distillation column) to further improve product purity. This additional gas-liquid separator is preferably a demister or a centrifugal droplet separator, particularly a centrifugal droplet separator. Preferably, the side outlet of the second distillation column is connected to a gas-liquid separator, such as a demister or a centrifugal droplet separator, particularly a centrifugal droplet separator. A stored polymerization inhibitor can be added to the product mixture. The stored polymerization inhibitor is preferably different from PTZ. More preferably, the stored polymerization inhibitor is selected from the group consisting of 2,4-dimethyl-6-tert-butylphenol (Topanol A), hydroquinone, butylated hydroxytoluene (2,6-di-tert-butyl-p-cresol), and / or 4-methoxyphenol (MeHQ), particularly 4-methoxyphenol.

[0072] The product mixture contains, relative to the total product mixture, preferably less than 100.0 ppm by weight, more preferably less than 50.0 ppm by weight, even more preferably less than 10.0 ppm by weight, even more preferably less than 5.0 ppm by weight, even more preferably less than 1.0 ppm by weight, even more preferably less than 0.5 ppm by weight, even more preferably less than 0.1 ppm by weight of 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxy (4-HT). The product mixture, for example, does not contain 4-HT.

[0073] The product mixture is preferably fed to the adsorption step in a liquid state. Depending on the process steps involved, the product mixture may be condensed before being fed to the adsorption step. Preferably, the condenser is arranged in fluid connection between the second distillation column and the adsorption unit.

[0074] The adsorbent material is typically a porous solid with a high surface area. Preferably, the adsorbent material comprises activated carbon and / or alumina. The alumina preferably comprises Al2O3. Furthermore, relative to the total alumina adsorbent material, the alumina preferably comprises less than 1.0 wt%, more preferably less than 0.5 wt% of Na2O, less than 0.10 wt%, more preferably less than 0.05 wt% of Fe2O3, and less than 0.10 wt%, more preferably less than 0.05 wt% of SiO2.

[0075] Activated carbon can be prepared from various carbon-donating precursors. The methods for converting it into its active form can vary. Examples of carbon-donating precursors include wood, sawdust and other wood waste, straw, coal such as bituminous coal or lignite, nut shells such as coconut shells, mineral oil tar, lignin, polysaccharides, polyacrylonitrile, bone, or peat. Additionally, coking products from lignite and hard coal can be used. Preferred examples include wood, cellulose, lignin, bituminous coal or lignite, nut shells, peat, or coke from hard coal. Activated carbon is preferably based on, for example, coal, wood, and / or coconut shells, particularly coal and / or coconut shells, for example, coal-based.

[0076] Activated carbon can be produced from a carbon-donating precursor using physical activation involving heating under a controlled atmosphere or chemical activation using strong acids, bases, or oxidants. The activation process produces a porous structure with a high surface area, which imparts a high impurity removal capacity to the activated carbon. The activation process can be modified to control the surface acidity. For example, the carbon-donating precursor can be activated by chemical activation with phosphoric acid or zinc chloride, or by gas activation with steam, oxygen, or a nitrite-containing gas. This pre-activated precursor is then preferably thermally converted, i.e., converted to activated carbon by coking. Activation methods are described, for example, in Ullmann's Encyclopedia of Industrial Chemistry, 5th edition, Volume AS (1986), pp. 124-140. Activation of the precursor carbon is preferably carried out by steam activation. The activated carbon can be washed with acid and / or water. Preferably, the adsorbent material is acid-washed. The activated carbon is preferably selected from the group consisting of: steam-activated activated carbon, acid-activated activated carbon, or activated carbon activated using at least one chemical activator; the chemical activator is selected from the group consisting of: alkali metal hydroxides, alkali metal carbonates, alkali metal sulfides, alkali metal sulfates, alkaline earth metal carbonates, alkaline earth metal chlorides, alkaline earth metal sulfates, and alkaline earth metal phosphates.

[0077] The iodine value of the adsorbent material is preferably in the range of 800 to 1500, more preferably in the range of 850 to 1150. Iodine value refers to the ability of the adsorbent material to adsorb iodine, and the unit of iodine value is mg / g. The iodine value can be determined according to ASTM D4607-2014.

[0078] The molasses value of the adsorbent is preferably between 200 and 500, more preferably between 200 and 240. Molasses value refers to the adsorption capacity of the adsorbent for molasses solution.

[0079] Preferably, as determined by the Brunauer-Emmett-Teller (BET) method based on nitrogen adsorption, the BET surface area of ​​the adsorbent material is 50 m². 2 / g to 2000m 2 / g, more preferably 200m 2 / g to 2000m 2 In the range of / g. In a first further preferred embodiment, particularly when the adsorbent material comprises or is activated carbon, the BET surface area of ​​the adsorbent material is in the range of 500 m². 2 / g to 2000m 2 / g, more preferably 900m 2 / g to 1300m 2 In a second, further preferred embodiment, particularly where the adsorbent material comprises alumina, the BET surface area of ​​the adsorbent material is in the range of / g. 2 / g to 500m 2 / g, more preferably 100m 2 / g to 300m 2 / g, or even more preferably 150m 2 / g to 250m 2 The BET surface area can be determined according to DIN ISO 9277:2003-05. Furthermore, the adsorbent material preferably has porosity in a dense packed column within the range of 10 vol% to 80 vol%, more preferably 30 vol% to 50 vol%, and even more preferably 35 vol% to 55 vol%, as determined, for example, by mercury porosimetry. The apparent density of the adsorbent material is preferably 200 kg / m³. 3 Up to 700kg / m 3 More preferably 400kg / m 3 Up to 550kg / m 3 The apparent density can be determined, for example, according to ISO 697:1981. The hardness of the adsorbent material is preferably in the range of 70 to 100, more preferably in the range of 75 to 99. The hardness can be determined, for example, according to ASTM D3802-89.

[0080] The pH value of the adsorbent material in water is preferably in the range of 2 to 11, more preferably 5 to 11, and even more preferably 6 to 8. The pH value of the adsorbent material can be determined, for example, according to ASTM D3838-05 (2011). For alumina, the pH value is preferably in the range of 8 to 10.

[0081] The weight-average particle size D of the adsorbent material was determined using the SediGraph method. 50 Preferably, the thickness is in the range of 5nm to 15mm, more preferably 0.3mm to 8.0mm, more preferably 0.4mm to 6.0mm, and even more preferably 0.5mm to 3.0mm.

[0082] The adsorbent material, particularly alumina, preferably has a pore size in the range of 30 Å to 100 Å, more preferably 50 Å to 70 Å.

[0083] The adsorbent material may contain up to 15% by weight, preferably up to 5% by weight, more preferably up to 3% by weight, and even more preferably up to 2% by weight, of water relative to the total adsorbent material. The adsorbent material may contain a binder. Typically, the binder content in the adsorbent material is less than 15% by weight, preferably less than 10% by weight, and more preferably less than 5% by weight, relative to the total adsorbent material.

[0084] The adsorbent material can be applied, for example, in the form of molded articles, granules, or powder. Molded articles can be prepared, for example, by extrusion from powder or in the form of granules. Extrudates typically have a cylindrical shape. Preferably, the adsorbent material is in the form of powder, granules, pellets, or cylinders. The diameter of the molded articles typically ranges from 0.5 mm to 10.0 mm. The adsorbent material is preferably applied in the form of granules, extrudates, and / or powder, more preferably in the form of granules and / or extrudates. The adsorbent material may contain particles, for example, with a particle size of 12 × 40 or 8 × 30 mesh, resulting in a weight-average particle size of about 1.0 mm and 1.4 mm, respectively.

[0085] Preferably, the product mixture is contacted with the adsorbent material at a temperature ranging from 0°C to 70°C, more preferably from 0°C to 50°C, even more preferably from 5°C to 40°C, and even more preferably from 10°C to 35°C. Preferably, the product mixture is contacted with the adsorbent material at an absolute pressure ranging from 0.01 MPa to 1.00 MPa, more preferably from 0.08 MPa to 0.50 MPa, and even more preferably from 0.10 MPa to 0.20 MPa.

[0086] Preferably, the PTZ concentration in the product composition, based on the total product composition, is lower than the PTZ concentration in the product mixture, based on the total product mixture. More preferably, the PTZ concentration in the product mixture, relative to the total product mixture, is in the range of 0.1 wt ppm to 100.0 wt ppm, more preferably 0.1 wt ppm to 10.0 wt ppm, even more preferably 0.5 wt ppm to 100.0 wt ppm, even more preferably 0.5 wt ppm to 10.0 wt ppm, even more preferably 0.5 wt ppm to 5.0 wt ppm, even more preferably 0.5 wt ppm to 3.0 wt ppm, or 0.6 wt ppm to 5.0 wt ppm. The PTZ concentration in the product mixture, based on the total product mixture, can also be, for example, 1.0 wt ppm to 10.0 wt ppm. Preferably, the PTZ concentration in the product composition, based on the total product composition, is 1.0 wt ppm or lower, more preferably less than 0.7 wt ppm, even more preferably less than 0.5 wt ppm, even more preferably less than 0.2 wt ppm, even more preferably less than 0.1 wt ppm. For example, the PTZ concentration in the product composition is in the range of 0.001 wt ppm to 1.000 wt ppm, preferably 0.001 wt ppm to 0.700 wt ppm, more preferably 0.001 wt ppm to 0.500 wt ppm, and even more preferably 0.010 wt ppm to 0.200 wt ppm, relative to the total product composition.

[0087] C1 to C 22The contents of -(meth)acrylates and PTZs can be determined, for example, by high-performance liquid chromatography (HPLC) or electron spin resonance (ESR) spectroscopy, as described in further detail in the following examples. Phenothiazines (PTZs) include 10H-phenothiazines (which are unsubstituted phenothiazines) and substituted phenothiazines, wherein the aryl hydrogens can be independently separated by straight or branched, aliphatic or aromatic C1 to C2 groups. 18 Partial replacement.

[0088] Preferably, the product composition contains less than 670 ppm by weight, more preferably less than 650 ppm by weight, of alcohol, particularly 2-ethylhexanol, relative to the total product composition. Preferably, the product composition contains less than 69 ppm by weight, more preferably less than 65 ppm by weight, of water, relative to the total product composition. Preferably, the product composition contains less than 2.9 ppm by weight, more preferably less than 2.5 ppm by weight, of siloxane, particularly polydimethylsiloxane (PDMS), relative to the total product composition. Typically, the product composition contains acetate, particularly 2-ethylhexyl acetate, in the range of 50 ppm to 500 ppm by weight, more preferably 100 ppm to 200 ppm by weight, and even more preferably 100 ppm to 150 ppm by weight, relative to the total product composition. Typically, the product composition contains (meth)acrylic acid, particularly acrylic acid, in the range of 5 ppm to 200 ppm by weight, more preferably 10 ppm to 100 ppm by weight, and even more preferably 10 ppm to 50 ppm by weight, relative to the total product composition.

[0089] Preferably, the product composition contains 2 to 50 wt ppm, more preferably 3 to 50 wt ppm, and particularly 5 to 20 wt ppm of MeHQ, relative to the total product composition. Typically, the product composition contains 0.5 wt ppm or less of PTZ derivatives and / or MeHQ derivatives, relative to the total product composition.

[0090] Preferably, the ratio of water content in the product mixture to water content in the product composition is at least 1.01, more preferably at least 1.05, even more preferably at least 1.10, and even more preferably at least 1.15. Typically, the ratio of water content in the product mixture to water content in the product composition is less than 5, for example, less than 3. The water content refers to the mass of water relative to the total mass of the product mixture and the product composition, respectively.

[0091] Preferably, the ratio between the content of alcohol, particularly 2-ethylhexanol, in the product mixture and the content of alcohol, particularly 2-ethylhexanol, in the product composition is at least 1.02, more preferably at least 1.03, and even more preferably at least 1.05. Typically, the ratio between the content of alcohol, particularly 2-ethylhexanol, in the product mixture and the content of alcohol, particularly 2-ethylhexanol, in the product composition is less than 1.50, for example, less than 1.20. The content of alcohol, particularly 2-ethylhexanol, refers to the mass of alcohol, particularly 2-ethylhexanol, relative to the total mass of the product mixture and the product composition, respectively.

[0092] Preferably, the ratio of the content of acetates, particularly 2-ethylhexyl acetate, in the product mixture to the content of acetates, particularly 2-ethylhexyl acetate, in the product composition is less than 1.30, more preferably less than 1.10, even more preferably less than 1.05, and even more preferably less than 1.02. Typically, the ratio of the content of acetates, particularly 2-ethylhexyl acetate, in the product mixture to the content of acetates, particularly 2-ethylhexyl acetate, in the product composition is at least 0.90, for example, at least 0.95. The content of acetates, particularly 2-ethylhexyl acetate, refers to the mass of acetates, particularly 2-ethylhexyl acetate, relative to the total mass of the product mixture and the product composition, respectively.

[0093] Preferably, the ratio between the content of siloxanes, particularly polydimethylsiloxane (PDMS), in the product mixture and the content of siloxanes, particularly PDMS, in the product composition is at least 1.10, more preferably at least 1.20, and even more preferably at least 1.25. Typically, the ratio between the content of siloxanes, particularly PDMS, in the product mixture and the content of siloxanes, particularly PDMS, in the product composition is less than 2.50, for example, less than 2.00. The content of siloxanes, particularly PDMS, refers to the mass of siloxanes, particularly PDMS, relative to the total mass of the product mixture and the product composition, respectively.

[0094] PTZ and MeHQ concentrations can be determined, for example, by high-performance liquid chromatography (HPLC) using a Phenomenex Kinetex 2.6u C18 100A 50×4.60mm column at 5μm, 40℃, with acetonitrile (ACN) containing 20% ​​water (phase A) and water containing 0.1% H3PO4 and 20% (ACN) (phase B) as the mobile phase at a flow rate of 1.5 mL / min. The gradients were 20%A / 80%B, 4.9 min / 80%A / 20%B, and 8.1 min / 20%A / 80%B. PTZ can be detected by UV at 253 nm, and MeHQ by UV at 290 nm.

[0095] Preferably, the product composition contains an acid value of less than 0.1 mg KOH / g. The acid value can be determined by acid titration, for example by titrating the sample with standardized potassium hydroxide (KOH) in a non-aqueous solvent until an endpoint is detected by a potential difference measurement. The result is expressed in mg KOH / g sample, representing the amount of base required to neutralize all acidic components.

[0096] The product composition preferably contains 1000 ppm by weight or less of 2-ethyl-4-methylpentanol relative to the total product composition. The product composition preferably contains 150 ppm by weight or less of n-butyl-2-ethylhexyl ether relative to the total product composition.

[0097] The method of the present invention can be carried out in a continuous, semi-batch, or batch manner, preferably in a continuous manner. The method of the present invention is used to prepare methacrylates or acrylates, preferably for the preparation of acrylates.

[0098] The adsorption step can be carried out, for example, in a fixed-bed adsorber, which can be designed as a horizontal or vertical adsorber or adsorption tank. Other options are moving adsorbents, such as moving beds or fluidized beds. Agitation methods (stirring the adsorbent material and product mixture in a stirred vessel, followed by filtration in a filter press) and layer filtration methods (forcing the product mixture through layers of adsorbent) are also feasible. Depending on the scale and adsorption equipment, mixing can affect the adsorption rate. Preferably, the adsorption step is carried out in a fixed-bed adsorber. A fixed-bed adsorber is preferably a cylindrical tube filled with adsorbent material, through which the product mixture flows. Fixed beds can have various configurations, including: a large bed, several horizontal beds, several parallel filled tubes, or multiple beds within their own shell. Based on the total volume of the fixed-bed adsorber, the volume of adsorbent material in the fixed-bed adsorber is, for example, in the range of 10% to 90% by volume. A fixed-bed adsorber can include two or more adsorption units so that it is possible to switch between adsorption units for regeneration or replacement. Regeneration can be carried out, for example, by washing with water, ethylene glycol, and / or methanol, or by contact with nitrogen, oxygen, carbon monoxide, carbon dioxide, and / or superheated steam. The preferred regeneration temperature is in the range of 250°C to 700°C, more preferably in the range of 250°C to 600°C.

[0099] Preferably, the product mixture is contacted with the adsorbent material in a continuous manner, and the adsorbent material is arranged as a fixed bed or slurry, particularly a fixed bed. In a more preferred embodiment, the product mixture is passed through a fixed bed of adsorbent material. When in contact with the adsorbent material, the product mixture can be conveyed by gravity or in the opposite direction of gravity (also referred to as downward or upward, respectively). Preferably, the flow rate (also referred to as specific load) of the product mixture is in the range of 0.10 bed volume / hour (BV / h) to 3.00 BV / h, more preferably 0.25 BV / h to 1.00 BV / h. Bed volume is understood as the geometric volume of the filled section of the adsorption unit, including the volume of the adsorbent material, the internal pore volume of the adsorbent material, and the void volume between the particles of the adsorbent material. The average relative velocity between the product mixture and the adsorbent material is preferably in the range of 0.10 m / h to 10.00 m / h, more preferably 0.30 m / h to 5.00 m / h.

[0100] Preferably, the ratio between the adsorbent material and the product mixture is in the range of 0.01 wt% to 20.00 wt%, more preferably 0.05 wt% to 10.00 wt%, even more preferably 0.05 wt% to 5.00 wt%, even more preferably 1.00 wt% to 5.00 wt%.

[0101] Before and / or after the adsorption step, additional polymerization inhibitors may be added to the product composition, particularly for storage purposes. Here, the additional polymerization inhibitor is preferably selected from the group consisting of phenolic compounds and quinones, more preferably o-, m-, or p-cresol (methylphenol), 2-tert-butylphenol, 4-tert-butylphenol, 2,4-di-tert-butylphenol, 2-methyl-4-tert-butylphenol, 2-tert-butyl-4-methylphenol, 2,6-tert-butyl-4-methylphenol, 4-tert-butyl-2,6-dimethylphenol, 6-tert-butyl-2,4-dimethylphenol, hydroquinone, 4-methoxyphenol, 2-methylhydroquinone, 2,5-di-tert-butylhydroquinone, or benzoquinone, especially 4-methoxyphenol (MeHQ).

[0102] Based on the total product composition, additional polymerization inhibitors may be added to the product composition at a concentration of up to 1000 ppm by weight, preferably up to 500 ppm by weight, more preferably up to 200 ppm by weight, most preferably up to 100 ppm by weight, and especially from 2 ppm to 50 ppm by weight.

[0103] The product composition can be combined with at least one additional monomer (also called a functional monomer) in a monomer composition for further processing, such as polymerization. The at least one additional monomer is typically different from C1 to C2. 22 - (meth)acrylate. The polymer may be a copolymer. Preferably, at least one additional monomer is at least partially selected from the group consisting of C1 to C1 of (meth)acrylate.25 -alkyl ester, more preferably C1 to C1 20 -alkyl esters, and even more preferably C1 to C8-alkyl esters and their derivatives, such as functionalized esters having functional groups comprising amino and / or urea groups; hydroxyalkyl acrylates, mono(meth)acrylate phenoxyethyl glycol esters, glycidyl acrylate, aminoalkyl acrylate, methacrylamide and its derivatives, unsaturated carboxylic acids, vinyl acetate, vinyl aromatic monomers and mixtures thereof. For example, the at least one additional monomer is at least partially selected from the group consisting of: ethyl methacrylate, 2-ethylhexyl methacrylate, 2-octyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, methyl acrylate, methyl methacrylate, methacrylic acid, itaconic acid, methacrylamide, styrene, vinyl acetate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, urea methacrylate; 2-aminoethyl methacrylate, 2-(2-oxoimidazolium-1-yl)ethyl methacrylate and mixtures thereof.

[0104] Preferably, the monomer composition for polymerization comprises: -10.0% to 95% by weight, preferably 50% to 95% by weight, more preferably 60% to 95% by weight of C1 to C 22 -(meth)acrylate; -5.0% to 90% by weight, preferably 5.0% to 50% by weight, more preferably 5.0% to 20% by weight, of at least one functional monomer, wherein the functional monomer is preferably selected from the group consisting of (meth)acrylate, methyl acrylate, methyl methacrylate and / or (meth)acrylic acid, particularly (meth)acrylic acid; and -0.0% to 85% by weight, preferably 0.0% to 45% by weight, more preferably 0.0% to 35% by weight of at least one oligomer, which is preferably selected from the group consisting of polyesters, polyethers, polycarbonates, polyurethanes, acrylics and / or epoxy oligomers.

[0105] The above components are calculated relative to the total monomer composition.

[0106] The total amount of these monomers in the monomer composition preferably accounts for 100% by weight.

[0107] C1 to C 22 - (meth)acrylates, product compositions and monomer compositions according to the invention, particularly curable ones. C1 to C 22- (meth)acrylate and optionally at least one other monomer, particularly copolymerizable. The product composition and / or monomer composition are preferably polymerized by emulsion polymerization in an aqueous reaction medium, by solution polymerization, by suspension polymerization or by bulk polymerization, particularly by bulk polymerization (collectively, polymerization).

[0108] For polymerization, conventional polymerization initiators and optional chain transfer agents can be used, wherein polymerization is preferably carried out at conventional temperatures in bulk, emulsion, or solution form (e.g., in water or liquid hydrocarbons). Polymerization can be carried out in organic solvents, particularly in organic solvents with boiling points in the range of 50°C to 250°C, preferably 60°C to 150°C, using a conventional amount of polymerization initiator, which is typically in the range of 0.01 wt% to 10 wt%, particularly 0.1 wt% to 4 wt%, based on the total weight of the monomers. The polymer or copolymer can be prepared by solution or bulk polymerization, for example by UV curing, at a temperature ranging from 20°C to 150°C, preferably from 40°C to 120°C, and at a pressure ranging from 0.1 bar (absolute) to 100.0 bar (absolute), preferably from 0.3 bar (absolute) to 10.0 bar (absolute), particularly under conditions where 0.01 wt% to 10.00 wt% of a peroxide or azo initiator, especially a photoinitiator such as Irgacure 184, is present based on the total weight of the monomers, and under conditions where 0 wt% to 300 wt%, more preferably 0 wt% to 150 wt% of an inert solvent is present based on the total weight of the monomers. The solvent is, for example, hydrocarbons, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, butyl acetate, aromatic solvents such as toluene, or mixtures thereof. In a preferred embodiment, the solvent used for polymerization is one or more ketones or acetates with a boiling point below 150°C under standard pressure (0.1 MPa, absolute value).

[0109] Suitable polymerization initiators include, for example, azo compounds, ketone peroxides, and alkyl peroxides, such as acyl peroxides like benzoyl peroxide, dilauryl peroxide, didecyl peroxide, and isononanoyl peroxide; alkyl esters like tert-butyl perpentanoate, tert-butyl per-2-ethylhexanoate, tert-butyl per-maleate, tert-butyl per-isononanoate, tert-butyl per-benzoate, and tert-pentyl per-2-ethylhexanoate; and dialkyl peroxides like dicumyl peroxide, tert-butylcumyl peroxide, di-tert-butyl peroxide, and peroxydicarbonate. Also usable as initiators are azo initiators, such as, for example, 2,2'-azobisisobutyronitrile, 2,2'-azobis(methyl isobutyrate), or 2,2'-azobis(2,4-dimethylpentanonitrile).

[0110] To facilitate polymerization, the product composition can also be mixed with a compound that reduces the degree of polymerization (called a chain transfer agent). Generally, the total amount of chain transfer agent (if present) should not exceed 1% by weight, based on the total amount of monomers to be polymerized. Suitable compounds include, for example, those with thiol groups, such as thiols, including mercaptoethanol, tert-butylthiol, mercaptosuccinic acid, ethylhexyl mercaptoacetate, 3-mercaptopropyltrimethoxysilane, or dodecyl mercaptoethanol.

[0111] Preferably, at least a portion of the product composition is fed into the method for preparing the polymer during polymerization. The polymer manufacturing method is preferably a semi-batch method.

[0112] After solution polymerization, the solvent can optionally be removed under reduced pressure and elevated temperature, for example, in the range of 100°C to 150°C. The polymer or copolymer can also be precipitated. The polymer or copolymer can then be used as a melt in a solvent-free state (preferably with a solvent content of less than 2% by weight based on the total composition).

[0113] The polymer preferably comprises poly(meth)acrylate, wherein the poly(meth)acrylate is mainly (i.e., greater than 50% by weight) composed of (meth)acrylate and its acid derivatives, particularly salts and esters (such as C1 to C2) of (meth)acrylate. 22 Polymers made of (meth)acrylates or amides.

[0114] The product composition is preferably used in radiation-curable compositions, such as radiation-curable coatings, printing inks, photoresists, adhesives, or for additive manufacturing. Radiation-curable compositions are particularly capable of UV curing. The methods and product compositions of the present invention are especially advantageous for radiation-curable applications because radiation-curable polymers and articles are prone to undesirable color changes or staining due to radiation treatment.

[0115] The term "capable of UV curing" describes a substance or composition that cures upon irradiation with ultraviolet light. The term "capable of UV curing" should be understood to mean that a UV-curable composition contains at least one compound having at least one radiation-sensitive group and initiates a polymerization or crosslinking reaction upon irradiation. Irradiation for polymerization and / or crosslinking is performed using ultraviolet (UV) light, particularly UV-C radiation. Examples of radiation sources are low-pressure mercury vapor lamps, medium-pressure mercury vapor lamps, high-pressure mercury vapor lamps, lasers, pulsed lamps (flash lamps), halogen lamps, excimer lamps, and LED lamps, including UV-A LEDs, UV-B LEDs, and UV-C LEDs. Combinations of different radiation sources are also possible.

[0116] Radiation-curable compositions typically contain one or more reactive components (particularly olefinically unsaturated components, such as C1 to C2). 22(Meth)acrylates, particularly 2-ethylhexyl acrylate (also known as functional monomers), and one or more other monomers and / or oligomers can be used to adjust viscosity and processing properties. Furthermore, radiation-curable compositions may contain oligomeric binders, which typically include more than one unsaturated group. Oligomeric binders can increase viscosity, toughness, or other end-use properties, particularly when pre-gelling alone is insufficient or when finer control of mechanical or rheological properties is required. For certain adhesive applications, radiation-curable compositions may be partially pre-gelled via controlled bulk polymerization to achieve a defined processing viscosity prior to final curing.

[0117] The reactive components suitable for radiation-curable compositions are preferably selected from monomers bearing acryloyl or methacryloyl groups and optionally oligomeric components. The oligomeric adhesive (also called an oligomer) preferably has a weight-average molecular weight in the range of 500 g / mol to 20,000 g / mol, more preferably 500 g / mol to 10,000 g / mol. The weight-average molecular weight and number-average molecular weight can be determined, for example, using gel permeation chromatography calibrated to polystyrene standards. The oligomeric adhesive preferably has an average of more than one olefinic unsaturated group, wherein a typical functionality value is 1.8 to 8.4, more preferably 2.0 to 6.0 groups / molecule. The oligomeric adhesive preferably comprises or is based on oligomers derived from polyesters, polyethers, polycarbonates, polyurethanes, acrylics, and epoxides, and mixtures thereof; polyethers, polyesters, polyurethanes, or mixtures thereof. Oligomers are typically obtained or functionalized by methods known in the art, such as by esterifying hydroxyl-functionalized precursors with (meth)acrylate, by opening ring-oxygen groups with (meth)acrylate, or by incorporating acrylated alcohols or diols during synthesis. Oligomers may optionally contain additional functional groups, such as hydroxyl, carboxyl, or amino groups, to modulate adhesiveness or reactivity.

[0118] Oligomeric adhesives, also known as oligomers, more preferably contain or are based on polyether acrylates (e.g., ethoxylated trimethylolpropane triacrylate oligomers, ethoxylated pentaerythritol acrylate oligomers), polyester acrylates (oligomeric polyester di / triacrylates), polyurethane acrylates (e.g., polyurethane oligomers end-capped with (meth)acrylate groups), epoxy acrylate blends (e.g., subsequently acrylated glycidyl ether-based oligomers), and bisphenol A diglycidyl ether diacrylate oligomers. The inclusion of oligomeric adhesives is optional and is particularly useful when increased viscosity, enhanced toughness, improved cohesion, or other customized properties beyond those provided by the pregel and monomer selection are required.

[0119] Radiation-curable compositions preferably contain at least one functional monomer, typically classified by functionality, such as monofunctional, difunctional, or polyfunctional monomers. Preferably, the radiation-curable composition comprises 5.00% to 99.99% by weight of monomers, depending on the target viscosity, reactivity, and end-use requirements. The functional monomers preferably have a weight-average molecular weight in the range of 50 g / mol to less than 500 g / mol, more preferably 50 g / mol to 400 g / mol. Monofunctional monomers, typically having a functionality in the range of 0.8 to 1.3, typically have a molecular weight in the range of 60 g / mol to 400 g / mol, preferably 100 g / mol to 250 g / mol. Monofunctional monomers are primarily used to reduce viscosity and adjust wetting and penetration properties. Examples of monofunctional monomers include isobornyl acrylate (IBOA), 2-phenoxyethyl acrylate, lauryl acrylate, isodecanyl acrylate, 2-ethylhexyl acrylate, and N-vinylpyrrolidone. Bifunctional monomers, typically having a functionality range of 1.7 to 2.3, generally have a molecular weight ranging from 100 g / mol to 400 g / mol, preferably from 150 g / mol to 350 g / mol. Bifunctional monomers are primarily used to increase crosslinking density and control mechanical properties. Examples of bifunctional monomers include dipropylene glycol diacrylate, diethylene glycol diacrylate, hexanediol diacrylate, and divinyl ethers such as triethylene glycol divinyl ether. Polyfunctional monomers, typically having a functionality range of 2.5 to 4.4, generally have a molecular weight ranging from 100 g / mol to 400 g / mol. Examples of polyfunctional monomers include, for example, trimethylolpropane triacrylate (TMPTA), pentaerythritol tetraacrylate (PETA), and ethoxylated (2) pentaerythritol tetraacrylate. Polyfunctional monomers provide high crosslinking density and rapid gelation properties.

[0120] Radiation-curable compositions may also contain unsaturated adhesion promoters and / or functional monomers, particularly for improving substrate interactions, interfacial adhesion, and adhesion to polar or treated surfaces. Suitable unsaturated adhesion promoters include carboxylic acid-functionalized vinyl, acrylic, or methacrylic acid monomers, such as acrylic acid and methacrylic acid; hydroxyl-functionalized vinyl, acrylic, or methacrylic acid monomers, such as 2-hydroxyethyl acrylate (HEA) and 2-hydroxyethyl methacrylate (HEMA); phosphorus-containing vinyl or (meth)acrylic acid monomers, such as vinylphosphonic acid and its esters, and phosphate esters or phosphonates derived from (meth)acrylic acid. Other adhesion-promoting unsaturated monomers include glycidyl (meth)acrylic acid (with epoxy functional groups combined with unsaturated (meth)acrylic acid) groups that can hydrolyze and bind to inorganic surfaces, sulfonic acid or sulfonate-functionalized (meth)acrylic acid esters, zwitterionic (meth)acrylic acid esters, and silane-functionalized (meth)acrylic acid esters (alkoxysilane-substituted (meth)acrylic acid esters). The selection and proportion of adhesion promoters depend on the substrate type, the desired bonding mechanism such as chemical bonding, hydrogen bonding or ionic interaction, and the curing strategy.

[0121] Radiation-curable compositions preferably contain one or more photoinitiators, particularly those enabling rapid polymerization upon exposure to suitable radiation. The one or more photoinitiators are preferably selected from acylphosphonates, such as ethylphenyl (2,4,6-trimethylbenzoyl)phosphonate; acylphosphine oxides, such as diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide or phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide; α-hydroxy ketones, such as 1-hydroxycyclohexylphenyl ketone; and thioxanthone derivatives, such as isopropylthioxanthone, 2,4-diethylthioxanthone. Additional types of photoinitiators include benzophenone derivatives and benzoin ethers, particularly for specific absorption or dual-curing strategies. The concentration of one or more photoinitiators is preferably in the range of 0.05% to 16.00% by weight, more preferably 0.1% to 5.0% by weight, relative to the total amount of all photoinitiators in the radiation-curable composition. The choice of photoinitiator generally depends on the emission spectrum of the selected light source, such as a UV A LED or a mercury lamp.

[0122] In addition, radiation-curable compositions may contain pigments, dyes, and other additives. Pigments are, for example, selected from copper phthalocyanine blue / green, quinacridone red / pink, benzimidazolone orange, carbon black, iron oxide, and / or titanium dioxide. Pigments provide opacity and / or color stability. Dyes are, for example, selected from azo, anthraquinone, and / or xatonnes, and are typically used for coloring or clearing. Typical additive functions include free radical scavengers or in-can stabilizers, such as nitrocellulose free radical derivatives, hindered phenolic antioxidants, and hydroquinone monomethyl ethers, to prevent premature gelation; dispersants, such as high molecular weight acrylic block copolymers or polyacrylamide-modified dispersants; rheology modifiers and thickeners, such as polysiloxane-modified polymers or associative thickeners; slip agents; defoamers; wetting agents; antistatic agents; and antioxidants. Specific functional examples include phosphorous acid or tri(alkyl) phosphonates as oxygen scavengers / antioxidants, phenothiazine inhibitors for storage stability, and polysiloxane flow modifiers for surface appearance.

[0123] A preferred formulation window is selected to provide an appropriate balance of reactive component content, reactivity, and processability. Since the oligomer binder is optional, the formulation portion emphasizes monomer content, and, where present, the oligomer binder is added to adjust viscosity and mechanical properties. In a preferred embodiment, the radiation-curable composition comprises, relative to the total radiation-curable composition, 0.00 wt% to 60.00 wt% of oligomer binder, 5.00 wt% to 99.94 wt% of monomers (such as mono / di / trifunctional mixtures and including adhesion promoters), 0.05 wt% to 20.00 wt% of photoinitiator, 0.00 wt% to 10.00 wt% of pigments and / or dyes, and 0.01 wt% to 5.00 wt% of additives. In a more preferred embodiment, the radiation-curable composition comprises, relative to the total radiation-curable composition, 0.0% to 40.0% by weight of oligomeric binders (such as polyurethane acrylate oligomers and / or polyester acrylate oligomers having 2-4 acryloyl groups), 35.0% to 70.0% by weight of monomers (such as 2-ethylhexyl acrylate, particularly a mixture of monofunctional 2-ethylhexyl acrylate, difunctional dipropylene glycol diacrylate, and trifunctional TMPTA), and optionally includes a bonding accelerator (such as acrylic acid, HEA, or vinyl phosphonate); 0.5% to 5.0% by weight of photoinitiators, such as mixtures of acyl phosphites and / or α-hydroxy ketones; and 0.0% to 20.0% by weight of pigments, dyes, and / or additives, such as phthalocyanine pigments, polymer dispersants, and / or in-can stabilizers. The radiation-curable composition may contain trace amounts of water or an inert solvent, typically less than 0.5% by weight relative to the total radiation-curable composition.

[0124] The radiation-curable composition is preferably a solvent-free product, meaning that the radiation-curable composition is not soluble or dispersed in water or organic solvents.

[0125] Actual formulations typically maintain a minimum combined fraction of reactive components sufficient to achieve the desired curing and mechanical properties. In particular, a radiation-curable composition contains 20% by weight or more of the combined reactive portion, such as the sum of oligomeric binders and monomers, relative to the total radiation-curable composition.

[0126] In a preferred embodiment, the radiation-curable composition, particularly the reactive component, oligomeric adhesive, monomer, and / or unsaturated bond accelerator, is at least partially based on the product composition. Preferably, the radiation-curable composition, particularly one or more monomers, is at least partially composed of the product composition.

[0127] The preferred viscosity target for radiation-curable compositions depends on their application and processing equipment. For example, the viscosity of a radiation-curable composition at 23°C is in the range of 1 mPa·s to 100 mPa·s, particularly for liquid, sprayable, or inkjet systems. Preferably, the viscosity of a radiation-curable composition at 23°C is in the range of 2 mPa·s to 20 mPa·s, particularly for liquid formulations, and more preferably in the range of 3 mPa·s to 18 mPa·s, particularly for binders used for dispensing or roll coating. Pre-gelled binders can be obtained by subjecting the filled container to a controlled dose of radiation or electron beam sufficient to produce a partially gelled thixotropic product that is handleable and orientable, while still curing to the final crosslinked state when the desired curing dose is applied to the substrate. If pre-gelling does not provide the desired final rheological or mechanical properties, oligomer binders can be incorporated to further increase viscosity and modify toughness or cohesion.

[0128] The curing conditions of the radiation-curable composition are selected to suit the photoinitiator system and the radiation source. Radiation sources include low-pressure, medium-pressure, and high-pressure mercury lamps, LED arrays (UV A / UV B / UV C), excimer lamps, lasers, and pulsed xenon lamps. The typical UV dose for complete curing varies depending on the formulation and the radiation source. Preferably, the UV dose is around 80 mJ / cm². 2 Up to 3000mJ / cm 2 More preferably 100mJ / cm 2 Up to 2000mJ / cm 2 Within a certain range. Curing of the radiation-curable composition can be carried out in air, in an oxygen-deficient atmosphere, or in an inert atmosphere. Inert atmospheres include, for example, nitrogen, argon, and / or carbon dioxide, and are particularly suitable when surface inhibition of curing must be minimized or when controlled pre-gelling is performed. Pre-gelling can be carried out at temperatures ranging from, for example, 15°C to 40°C, particularly in a defined gas atmosphere.

[0129] Radiation-curable compositions can be applied to surfaces using conventional methods, including roller coating, blade or doctor blade coating, spraying, brushing, lamination, transfer coating, and various printing techniques such as inkjet, flexographic printing, gravure printing, screen printing, and offset printing. The choice of application method affects the target viscosity, thixotropy, and gel behavior.

[0130] Formulation improvements include adjusting reaction chemistry, monomer selection (including adhesion promoters), photoinitiator type selection, and radiation source selection to optimize the desired final properties of the cured composition, such as hardness, elasticity, adhesion, thermal stability, and chemical resistance. Optimization development includes, for example, evaluating curing kinetics via photoluminescence DSC or RT FTIR; rheological properties, adhesion properties, thermal and mechanical testing; and assessment, migration, and conditioning considerations of residual monomers. For iterative optimization of radiation-curable compositions, it is preferable to begin with monomer-rich formulations, wherein 5.00 wt% to 99.94 wt%, particularly 50.00 wt% to 99.94 wt%, of monomers is suitable, and when pre-gelling alone is insufficient, oligomers are preferably added incrementally to achieve the desired processing viscosity and mechanical properties.

[0131] As an alternative to radiation, the product composition or the resulting polymer can be cured by heating to a temperature of 80°C to 180°C, more preferably 100°C to 150°C, and particularly preferably 115°C to 140°C, especially after the curable composition has been applied to a surface. The heating is preferably carried out over a period of 5 to 60 minutes, more preferably 10 to 25 minutes, and particularly preferably 15 to 20 minutes.

[0132] To prepare the adhesive coating, the adhesive is preferably applied as a melt to the carrier substrate, for example at a temperature of 50°C to 160°C, preferably 80°C to 150°C, or above 100°C. The application rate of the adhesive is preferably 5 g / m³. 2 Up to 50g / m 2 A particularly preferred value is 10 g / m³. 2 Up to 30g / m 2 .

[0133] Preferred carrier substrates include paper and polymer films, such as films made of polyethylene (PE), polypropylene (PP), oriented polypropylene (OPP), polyethylene terephthalate (PET), or polyvinyl chloride (PVC). The film thickness is preferably 30 μm to 150 μm. However, thinner films with a thickness of 20 μm may be used in some applications (e.g., sun-protective films for vehicle windows or PVC labels), and very large films with a thickness of up to 350 μm are used in the field of automotive body surface protection.

[0134] The adhesive described above has the following benefits: low volatile organic compound (VOC) content, low odor, good adhesion to metal substrates, good coatability on carrier substrates, and a good balance of cohesion and adhesion, including high bond strength at elevated temperatures.

[0135] In another embodiment, the polymer composition is present in the form of an aqueous polymer dispersion, and therefore the polymer composition comprises polymerized via emulsion polymerization, particularly via C1 to C2 polymerization. 22 A dispersed polymer or copolymer formed by emulsion polymerization of (meth)acrylates and optionally other monomers.

[0136] Emulsion polymerization is preferably the free radical emulsion polymerization of olefinically unsaturated, free radical polymerizable compounds (monomers). Emulsion polymerization involves polymerizing olefinically unsaturated compounds (monomers) in water, using ionic and / or nonionic emulsifiers and / or protective colloids or stabilizers as surfactants to stabilize monomer droplets and subsequently polymer particles formed from the monomers. The amount of surfactant used is typically from 0.1 to 10.0 parts by weight, preferably from 0.2 to 5.0 parts by weight, based on 100 parts by weight of the monomer to be polymerized.

[0137] A detailed description of suitable protective colloids can be found in Houben-Weyl, Methoden der organischenChemie [Methods of Organic Chemistry], Vol. XIV / 1, Makromolekulare Stoffe [Macromolecular Materials], Georg-Thieme-Verlag, Stuttgart, 1961, pp. 411-420. Useful emulsifiers include anionic, cationic, and nonionic emulsifiers. As the surfactant, emulsifiers with a molecular weight typically lower than 2000 g / mol compared to the protective colloid are preferred. Anionic and nonionic emulsifiers are preferred as the surfactant. Commonly used accompanying emulsifiers are, for example, ethoxylated fatty alcohols (EO degree: 3 to 50, alkyl group: C8 to C5). 36 Ethoxylated monoalkylphenols, dialkylphenols, and trialkylphenols (EO degrees: 3 to 50, alkyl groups: C4 to C9), alkali metal salts of dialkyl esters of sulfosuccinic acid, and alkyl sulfates (alkyl groups: C8 to C9). 12 Alkali metal salts and ammonium salts, ethoxylated alkanols (EO degree: 4 to 30, alkyl group: C) 12 To C 18Alkali metal salts and ammonium salts of alkylphenols (EO degree: 3 to 50, alkyl group: C4 to C9), alkali metal salts and ammonium salts of alkyl sulfonic acids (alkyl group: C4 to C9). 12 To C 18 Alkali metal salts and ammonium salts, and alkylaryl sulfonic acids (alkyl groups: C9 to C10). 18 Alkali metal salts and ammonium salts.

[0138] Other suitable emulsifiers are compounds of the following general formula.

[0139] Where R 5 and R 6 It is hydrogen or C4 to C 14 Alkyl groups are not simultaneously hydrogen, and X and Y can be alkali metal ions and / or ammonium ions. R 5 and R 6 Preferably, it has a straight-chain or branched alkyl group or hydrogen having 6 to 18 carbon atoms, particularly having 6, 12, and 16 carbon atoms, wherein R 5 and R 6 They are not both hydrogen. X and Y are preferably sodium ions, potassium ions, or ammonium ions, with sodium ions being particularly preferred. Where X and Y are sodium, R 5 It is a branched alkyl group with 12 carbon atoms and R 6 For hydrogen or R 5 The compounds are particularly advantageous. Industrial mixtures containing 50% to 90% by weight of the monoalkylated product are typically used. Commercially available suitable emulsifiers include, for example, Dowfax. ® 2 A1, Emulan ® NP 50, Dextrorot ® OC 50, Emulgator825, Emulgator 825 S, Emulan ® OG, Texapon ® NSO, Nekanil ® 904 S, Lumiten ® I-RA, Lumiten ® E 3065, Disponil ® FES 77, Lutensol ® AT 18, Steinapol ® VSL, Emulphor ®NPS25. An ionic emulsifier or protective colloid is used. Ionic emulsifiers are particularly preferred, especially salts and acids such as carboxylic acids, sulfonic acids, and sulfates, sulfonates, or carboxylates. Mixtures of ionic and nonionic emulsifiers can also be used.

[0140] Emulsion polymerization can also be carried out in the presence of protective colloids. Protective colloids are polymeric compounds that bind a large amount of water upon solvation and can stabilize dispersions of water-insoluble polymers. Unlike emulsifiers, they generally do not reduce the interfacial surface tension between polymer particles and water. The number-average molecular weight of protective colloids is particularly high above 1000 g / mol.

[0141] Emulsion polymerization can be initiated using water-soluble initiators. Examples of water-soluble initiators include ammonium and alkali metal salts of disulfuric acid peroxide (e.g., sodium disulfuric acid peroxide), hydrogen peroxide, or organic peroxides, such as tert-butyl hydroperoxide. So-called reduction-oxidation (redox) initiator systems are also suitable as initiators. Redox initiator systems typically consist of at least one inorganic or organic reducing agent and an inorganic or organic oxidizing agent. The oxidizing component is, for example, an emulsion polymerization initiator already mentioned above. The reducing component is, for example, an alkali metal salt of sulfurous acid, such as sodium sulfite or sodium bisulfite; an alkali metal salt of disulfite, such as sodium bisulfite; bisulfite addition compounds of aliphatic aldehydes and ketones, such as acetone bisulfite; or a reducing agent, such as hydroxymethanesulfinic acid and its salts, or ascorbic acid. Redox initiator systems can be used with soluble metal compounds, the metal component of which can be present in multiple valence states. Typical redox initiator systems include, for example, ascorbic acid / ferrous(II) sulfate / sodium persulfate, tert-butyl hydroperoxide / sodium metabisulfite, and tert-butyl hydroperoxide / sodium hydroxymethanesulfinate. Individual components, such as the reducing agent component, can also be mixtures, such as a mixture of sodium salt of hydroxymethanesulfinate and sodium metabisulfite.

[0142] Water-soluble initiators are typically used in aqueous solutions, with the lower concentration limit determined by the acceptable amount of water in the dispersion and the upper concentration limit determined by the solubility of the specific compound in water. Based on the monomers to be polymerized, the initiator concentration is typically from 0.1% to 30% by weight, preferably from 0.5% to 20% by weight, and even more preferably from 1.0% to 10% by weight. Two or more different initiators can also be used in emulsion polymerization.

[0143] Chain transfer agents can be used in emulsion polymerization. It is preferred not to use chain transfer agents. When chain transfer agents are used, their amount is preferably at least 0.01 parts by weight per 100 parts by weight of monomer to be polymerized, for example, 0.01 to 5.00 parts by weight, or 0.01 to 3.00 parts by weight, preferably 0.01 to 0.75 parts by weight of chain transfer agent. This allows the molar mass of the emulsion polymer to be controlled / reduced through chain termination reactions. Suitable chain transfer agents for emulsion polymerization are, in particular, organic compounds containing sulfur in bonded form (e.g., compounds having thiol groups), aliphatic and / or aryliphatic halogen compounds, aliphatic and / or aromatic aldehydes, unsaturated fatty acids (e.g., oleic acid), dienes having non-conjugated double bonds (e.g., divinylmethane, terpineol, or vinylcyclohexene), hydrocarbons having readily extractable hydrogen atoms (e.g., toluene), organic acids or their salts (e.g., formic acid, sodium formate, ammonium formate), alcohols (e.g., isopropanol), and phosphorus compounds (e.g., sodium hypophosphite). Alternatively, compatible mixtures of the above-described chain transfer agents may be used. Preferred organic compounds containing sulfur in a bonded form include, in particular, tert-butylthiol, ethyl thioglycolate, mercaptoethanol, mercaptopropyltrimethoxysilane, tert-dodecylthiol, thiodiethylene glycol, ethyl thioethanol, di-n-butyl sulfide, 2-isopropyl sulfide, di-n-octyl sulfide, diphenyl sulfide, diisopropyl disulfide, 2-mercaptoethanol, 1,3-mercaptopropanol, 3-mercaptopropane-1,2-diol, 1,4-mercaptobutanol, mercaptoacetic acid, 3-mercaptopropionic acid, mercaptosuccinic acid, thioacetic acid, and thiourea. Particularly preferred thio compounds are tert-butylthiol, ethyl mercaptoacetate, mercaptoethanol, mercaptopropyltrimethoxysilane, 2-ethylhexyl mercaptoacetate (EHTG), isooctyl 3-mercaptopropionate (IOMPA), or tert-dodecylthiol (tDMK).

[0144] Emulsion polymerization can usually be carried out using well-known methods, especially free radical emulsion polymerization techniques. The conditions required for the emulsion polymerization of monomers are well known to those skilled in the art, for example from the prior art cited at the beginning and from “Emulsions polymerisation”, in Encyclopedia of Polymer Science and Engineering, Vol. 8, p. 659 and subsequent pages (1987); DC Blackley, in High PolymerLatices, Vol. 1, p. 35 and subsequent pages (1966); H. Warson, The Applications of Synthetic Resin Emulsions, Chapter 5, p. 246 and subsequent pages (1972); D. Diederich, Chemie in unsererZeit, 24, pp. 135-142 (1990); Emulsion Polymerisation, Interscience Publishers, New York (1965); DE-A 40 03 422, and Dispersionen synthetischer Hochpolymere, F. Holscher, Springer-Verlag, Berlin (1969).

[0145] Emulsion polymerization is typically carried out at temperatures between 30°C and 130°C, preferably between 50°C and 95°C. The aqueous reaction medium can consist of water alone, or a mixture of water and a miscible liquid such as methanol. The term "aqueous" refers to a solvent system primarily based on water, preferably containing no or less than 10%, 5%, or 1% by weight of organic solvents based on the total solvent. Water alone is preferred.

[0146] The aqueous reaction medium preferably comprises a buffer salt, which preferably comprises citrate, carbonate, borate and / or phosphate. More preferably, the buffer salt comprises a phosphate selected from the group consisting of: alkali metal dihydrogen phosphate, alkali metal hydrogen phosphate, alkali metal phosphate, alkali metal diphosphate, alkali metal triphosphate, alkali metal polyphosphate, alkali metal metaphosphate and mixtures thereof.

[0147] Based on the total aqueous reaction medium, the aqueous reaction medium may in principle also contain small amounts, especially 5% by weight or less, of water-soluble organic solvents, such as ethylene glycol, methanol, ethanol, isopropanol, butanol, pentanol and / or acetone.

[0148] Emulsion polymerization can be carried out in batch or feed-based methods, including staged and gradient operation modes of feed methods. A preferred feed method (also known as a semi-batch method) involves initially loading a portion of the polymerization batch, heating it to the polymerization temperature, and initiating polymerization before supplying the remaining polymerization batches, typically via multiple spatially separated feeds (one or more of which contain monomers in pure or emulsified forms), continuously, in stages, or with concentration gradients, while maintaining polymerization within the polymerization zone.

[0149] Polymer seeds can also be introduced during polymerization to more effectively control particle size. Seed latex is an aqueous dispersion of finely divided polymer particles. For example, polystyrene-based or polymethyl methacrylate-based latexes are suitable. A preferred seed latex is a polystyrene seed latex.

[0150] Preferably, monomers such as product compositions are polymerized in the presence of polymer seeds. Polymer seeds, or seed latex, are polymer particles present in the aqueous reaction medium prior to the start of metering the monomer composition. Polymer seeds can help to better control the particle size of the final aqueous polymer dispersion obtained in emulsion polymerization.

[0151] The methods of adding initiators to the polymerization vessel during emulsion polymerization are known to those skilled in the art. They can be added entirely to the polymerization vessel first, or used continuously or in stages at their consumption rate during emulsion polymerization. This depends specifically on the chemistry of the initiator system and the polymerization temperature. Preferably, a portion is added first, and the remainder is supplied to the polymerization zone at its consumption rate. To remove residual monomers, the initiator is typically added after the actual emulsion polymerization has terminated, i.e., after at least 95% monomer conversion. In feeding methods, the components can be added to the reactor from above, from the side, or from below through the bottom of the reactor.

[0152] In emulsion polymerization, the aqueous dispersion of the polymer typically has a solids content of 15% to 75% by weight, preferably 40% to 75% by weight, and particularly preferably not less than 45% by weight, relative to the total aqueous dispersion. To obtain high reactor space / time yields, dispersions with very high solids content are preferred. To achieve solids content greater than 60% by weight, bimodal or multimodal particle sizes should be established to maintain relatively low viscosity. For example, next-generation particles can be produced by adding seeds, by adding an excess dose of emulsifier, or by adding a fine emulsion. Another advantage associated with low viscosity at high solids content is improved coating properties at high solids content. The size distribution of the dispersion particles can be unimodal, bimodal, or multimodal.

[0153] The neutralization of the acid groups in the resulting polymer can be achieved by adding a neutralizing agent during or after polymerization, wherein the acid groups are completely or partially neutralized by adding a base. The neutralizing agent can be added, for example, simultaneously with the feed of the monomer mixture in a separate feed. Preferably, the neutralizing agent is selected from water-soluble hydroxides, oxides, carbonates, bicarbonates (e.g., bicarbonates), acetates, citrates, borates, phosphates, and hydrogen phosphates of alkali metals or alkaline earth metals. Other neutralizing agents are also possible, such as ammonia or water-soluble organic amines, such as lower aliphatic amines. Ammonia is preferred as the neutralizing agent. Preferably, the pH of the polymer dispersion is adjusted to a pH greater than 4.5, and more particularly to a pH between 5 and 8.

[0154] Emulsion polymerization can produce a variety of products, such as sealants, coatings, putties, printing materials, adhesives, and / or paints. Adhesives prepared by emulsion polymerization can be used, for example, to prepare self-adhesive articles. The article is at least partially coated with the adhesive. Self-adhesive articles can be self-adhesive labels, self-adhesive tapes, or self-adhesive films, including graphic films and protective films. Suitable carrier materials are, for example, paper, plastic films, and metal foils. Self-adhesive tapes can be tapes coated with the aforementioned substances on one or both sides. Self-adhesive labels can be labels made of paper or thermoplastic films. Tapes made of thermoplastic films are particularly preferred. Suitable thermoplastic films include, for example, films made of polyolefins (e.g., polyethylene or polypropylene), polyolefin copolymers, polyesters (e.g., polyethylene terephthalate), polyvinyl chloride, or polyacetate. Foam carriers are also possible. The surface of the carrier can be rigid or flexible. Preferred substrates for self-adhesive articles are paper and polymer films.

[0155] Embodiments of the present invention are shown in the accompanying drawings and are further described below.

[0156] Figure 1 The following are examples of methods for manufacturing C1 to C 22 A schematic diagram of the apparatus and method for preparing C1 to C2 acrylates. 22 The apparatus 1 for producing (meth)acrylate includes a reactor 3, a first distillation column 5, and a second distillation column 7. Here, the reactor 3 exists in the form of a reactor cascade 21 and includes a distillation unit 23 and a phase separator 25. The reactor 3 is arranged in a first fluid connection 9 with the first distillation column 5. The outlet 11 of the first distillation column 5 is arranged in a second fluid connection 13 with the side feed inlet 15 of the second distillation column 7. The second distillation column 7 includes a side outlet 17 through which the product mixture 2 is extracted.

[0157] An alcohol and (meth)acrylic acid are provided in reactor 3 and converted to C1 to C2 in the presence of a catalyst. 22 -(meth)acrylates, wherein C1 to C1 are obtained 22A crude mixture of (meth)acrylates. The crude mixture is purified in a first distillation column 5 and a second distillation column 7. At least a portion of the crude mixture is introduced into the first distillation column 5, which has a top 19 and a bottom 27. The high-boiling fraction is directed from the bottom 27 of the first distillation column 5 to a high-boiling treatment unit 29. The purified mixture is removed from the top 19 of the first distillation column 5 and introduced into the second distillation column 7 via a side feed inlet 15. The product mixture 2 is fed into an adsorption unit 4 comprising adsorbent material 6, and the product composition 8 is removed from the adsorption unit 4.

[0158] The invention will be explained in more detail through the following examples and comparative examples.

[0159] Examples and Comparative Examples Use the following materials and abbreviations: 2-EHA: 2-Ethylhexyl acrylate AA: Acrylic acid, obtained from BASF. Irgacure ® 184 photoinitiator PTZ: Phenothiazine HDDA hexanediol diacrylate, Laromer ® Obtained from BASF AC activated carbon AC Norit 97876 Activated Carbon (Wood-based, Powder, Chemically Activated, Sigald) AC Norit GCN 3070 Activated Carbon (Coconut Shell Based, Granules) AC Norit ROW 08 Supra Activated Carbon (Coconut Shell Based, Granular) AC Norit ROX 0.8 activated carbon (acid washing, neutral pH, extrusion, iodine value 1000, BET area 1100m²) 2 / g) AC 31616 activated carbon (powder, Supelco) AC C3345 activated carbon (powder, untreated, Sial, 100-400 mesh) CPG LF activated carbon (coal-based, acid-washed pH 5-8, granular, particle size 1mm, sieve size 12×40, minimum molasses value 210, minimum iodine value 950, voids in dense packed columns 36-40% by volume, BET area 950m²) 2 / g) Norit GAC 1240 AFX Activated Carbon (Coal-based, Granular, 12×40 mesh) Norit GCN 1240 Activated Carbon (Alkaline pH, Coconut Shell Based, Granules, Granule Mesh Size 12×40, Iodine Value 1050, BET Area 1150m²) 2 / g) Norit GCN 1240 Plus Activated Carbon (Acid-washed, Neutral pH, Coconut Shell Based, Granular, 12×40 Mesh Size, Iodine Value 1100, BET Area 1200m²) 2 / g) Alox 90 neutral alumina (Active I, neutral, pH 6.8-7.8, 70% particle size between 0.063 and 0.200 mm) Alox basic alumina (activated Bockmann number I, alkaline, pH 9-10, BET area 205m²) 2 / g) Cotton cotton Kieselgel 60 silicone Chemizorb ion exchange resin, purchased from Merck Ambosol MP25 Magnesium Silicate A) Adsorption of PTZ from (meth)acrylate A1) Adsorption of PTZ from (meth)acrylate, laboratory scale Different amounts of different adsorbent materials (see Table 1) were placed into 35 mL sealable glass containers. 22.5 mL of 2-EHA containing different amounts of PTZ (see Table 1) was added. The resulting suspension was stirred at 600 rpm using a magnetic stirrer at room temperature (approximately 20°C). Samples were taken at 30 minutes, 2 hours, and 24 hours. The sample liquid was filtered through a Millex GV 13 mm, 0.22 μm filter, and the PTZ content was determined by electron spin resonance (ESR) spectroscopy after derivatization with phosphomolybdic acid (MPS). For this purpose, 100 mg of phosphomolybdic acid was added to the sample and then transferred to a glass tube with an outer diameter of 4 mm and an inner diameter of 3 mm; the measured value was 335 mT. The signal amplitude corresponds to the PTZ concentration in the sample.

[0160] Table 1: Adsorption of PTZ from 2-EHA

[0161] In addition, a 10 mL syringe was plugged with absorbent cotton and filled with 1.00 g (approximately 2 mL) of a different adsorbent material (see Table 2). Subsequently, 8 mL of 2-EHA containing 1 wt ppm PTZ was passed through the syringe. The filtrate was passed through a microfilter (Millex FG, 13 mm) before further analysis, and the PTZ content was determined by electron spin resonance (ESR) spectroscopy after derivatization with phosphomolybdic acid (MPS) as described above.

[0162] The PTZ concentrations in the feed and filtrate are shown in Table 2.

[0163] Table 2: Adsorption of PTZ from 2-EHA

[0164] In addition, a 10 mL syringe was plugged with degreased cotton and filled with 1.00 g (approximately 2 mL) of activated charcoal powder AC Norit GCN3070. Subsequently, 8 mL of different (meth)acrylates containing 2.5 ppm by weight PTZ was passed through the syringe. Before further analysis, the filtrate was passed through a microfilter (Millex FG, 13 mm), and the PTZ content was determined by electron spin resonance (ESR) spectroscopy after derivatization with phosphomolybdic acid (MPS) as described above.

[0165] The PTZ concentrations in the feed and filtrate are shown in Table 3.

[0166] Table 3: Adsorption of PTZ from (meth)acrylate

[0167] A2) Adsorption of PTZ from 2-EHA, technology scale I Different activated carbon-type adsorbents (see Tables 4, 5, and 6) were added to a small apparatus. 1.7 kg of 2-EHA containing a stabilizer was loaded into a 4 L double-jacketed glass reactor equipped with a glass lid, a three-stage cross-shaped stirrer thermocouple, and an enhanced condenser. 17 g of the corresponding adsorbent was added. The mixture was stirred at 230 rpm for 20 to 23 hours at atmospheric pressure and room temperature (21.0°C to 22.5°C), with lean air introduced at a rate of 1 L / h. Approximately 250 g to 450 g of sample was removed from the mixture after 1, 2, and 4 hours, and approximately 1 day, respectively. The mixture was then filtered using a pressure-driven filter funnel with a 14 cm depth filter (Seitz K100) at a pressure differential of 1000 hPa to 1200 hPa. The PTZ content in the clarified filtrate was analyzed by ESR, the MeHQ content by HPLC, and the polydimethylsiloxane content by NMR. The analytical methods are described below.

[0168] Table 4: Adsorption of PTZ from 2-EHA

[0169] Table 5: MeHQ adsorption from 2-EHA

[0170] Table 6: Adsorption of polydimethylsiloxane from 2-EHA

[0171] Then, 2.8 kg of 2-EHA containing stabilizer was loaded into a 4 L double-jacketed glass reactor equipped with a glass lid, a three-stage cross-shaped stirrer thermocouple, and an enhanced condenser. 28 g of activated carbon (Norit ROX 0.8) was added. The mixture was stirred at 230 rpm at atmospheric pressure and room temperature (21 °C), with lean air introduced at a rate of 1 L / h. After 1, 2, 4, 6, 8, 10, and 24 hours, approximately 250 g to 450 g of sample was removed from the mixture and filtered using a pressure filter funnel at a pressure differential of 1000 hPa using a 5 cm depth filter (Seitz K100). After 74 h, the remaining mixture was filtered using a pressure filter funnel at a pressure differential of 1 bar using a 5 cm depth filter (Seitz K100). The PTZ and MeHQ contents in the obtained clarified filtrate were analyzed by HPLC as described below. The results are shown in Table 7.

[0172] Table 7: Adsorption of PTZ and MeHQ from 2-EHA using activated carbon

[0173] A3) Adsorption of PTZ from 2-EHA, technology scale II The adsorption step was carried out in a pilot-scale apparatus equipped with a cross-shaped stirrer and inertized with lean air. 3 In an enamel-lined reactor, 900 kg of 2-EHA containing 1.4 ppm PTZ and 16.4 ppm MeHQ was added and stirred at 60 rpm. 9 kg of Norit ROX 0.8 activated carbon was added, and the mixture was again inert with lean air at 400 L / h for 1 hour. The mixture was stirred at 60 rpm for 6 hours at atmospheric pressure and a jacket temperature of 20°C, with lean air introduced at 200 L / h. The reaction mixture was filtered using a 400 L modular filter equipped with a Seitz K100 filter plate covered with a 7 μm polypropylene filter cloth at a differential pressure of 300 hPa and collected in two containers. Four batches were completed under the same conditions. The PTZ and MeHQ contents in the resulting clear filtrates from all containers were analyzed by HPLC as described below. The average MeHQ content in all containers was 2.6 ppm PTZ. No PTZ was detected.

[0174] A4) Adsorption of PTZ from 2-EHA, technology scale III The adsorption step was carried out in a fixed-bed adsorber using activated carbon CPG LF. The product composition was then removed from the fixed-bed adsorber. As described below, the product mixture fed into the fixed-bed adsorber and the product composition removed from the fixed-bed adsorber were analyzed. Four samples were taken from the continuous method, and the average values ​​relative to the total product mixture and product composition are shown in Table 8. Table 8: Adsorption of 2-EHA using activated carbon

[0175] PTZ and MeHQ concentrations were determined by HPLC using a Phenomenex Kinetex 2.6u C18 100A 50×4.60mm, 5μm, 40℃ mobile phase containing acetonitrile (ACN) with 20% water (phase A) and water containing 0.1% H3PO4 and 20% (ACN) (phase B) at a flow rate of 1.5 mL / min. The flow gradients were 20%A / 80%B, 4.9 min / 80%A / 20%B, and 8.1 min / 20%A / 80%B. PTZ was detected by UV at 253 nm, and MeHQ by UV at 290 nm.

[0176] 2-Ethylhexanol, 2-EHA, and acrylic acid were analyzed by gas chromatography (GC). For GC analysis, a gas chromatograph equipped with a 280°C split injector and a 320°C flame ionization detector (FID) was used. Chromatographic conditions included an MN-Optima 35MS 30m × 0.25mm × 0.25µm column and a temperature program with the following temperature ramp: 60°C – 15°C / min – 300°C (17 min). Hydrogen was used as the carrier gas.

[0177] Water content determined by Karl-Fischer titration according to DIN 51777:2020-04.

[0178] The content of polydimethylsiloxane was determined by quantitative nuclear magnetic resonance spectroscopy (NMR), with dimethyl terephthalate (DMT) used as an internal standard. The analyte was quantified by comparing the peak area ratio of the analyte to the internal standard.

[0179] B) Preparation of UV-curable bulk polymers Example 1, Example 2 and Comparative Example 1 Add 45g 2-EHA, 5g AA, and 0.025g Irgacure to a 200mL glass bottle. ® 184. The applied 2-EHA contained varying amounts of PTZ (see Table 9). The mixture was stirred under inert gas and cured for 120 seconds with a 400W mercury lamp. The distance between the lamp and the sample was 30 cm. Then, 5 g of HDDA was added.

[0180] Observe the following properties : Table 9: Bulk Polymerization of 2-EHA

[0181] The iodine color number is a standardized index according to DIN 6162-2014-09 and is used to assess the color depth of transparent liquids similar to iodine-potassium iodide solutions. The scale ranges from 0 (colorless) to 500 (dark brown), expressed as the mass of iodine in mg per 100 mL of potassium iodide solution.

[0182] The PTZ content of acrylates in the lower ppm range affects the polymerization process and polymer properties. In the presence of 3.0 ppm PTZ in 2-EHA, the viscosity of the polymer mixture and the maximum temperature during curing decreased. Furthermore, increased coloration was observed with increasing PTZ content in the acrylate.

[0183] List of icon numbers 1 device 2. Product Mixture 3 reactors 4 Adsorption Units 5 First Distillation Column 6 Adsorption materials 7 Second Distillation Column 8 Product Composition 9 First fluid connection 11 Exports 13 Second fluid connection 15 side feed inlets 17 Side exit 19 Top 21 Reactor Cascade 23 Distillation Units 25-phase separator 27 Tower Base 29. High-boiling-point treatment unit.

Claims

1. Used for preparing C1 to C2 22 A method for producing (meth)acrylates, the method comprising an adsorption step, wherein the acrylate containing C1 to C2 is subjected to an adsorption step. 22 A mixture of (meth)acrylate and phenothiazine (PTZ) products (2) is contacted with an adsorbent material (6) to obtain a product composition (8).

2. The method according to claim 1, further comprising the following steps: - A conversion step in which alcohols or olefins and (meth)acrylic acid compounds, particularly (meth)acrylic acid, are converted to the C1 to C1 compounds in the presence of a catalyst. 22 -(meth)acrylate, and obtain the C1 to C2 acrylate. 22 A crude mixture of (meth)acrylates, - Purification step, wherein the crude mixture is subjected to at least one distillation stage to obtain the product mixture (2).

3. The method according to claim 1 or 2, wherein, based on the total product mixture (2), the product mixture (2) comprises at least 95% by weight, particularly at least 98% by weight, of the C1 to C2 compounds. 22 - (meth)acrylate.

4. The method according to any one of claims 1 to 3, wherein C1 to C 22 - (meth)acrylates are C1 to C8- (meth)acrylates, especially 2-ethylhexyl acrylate, methyl acrylate, ethyl acrylate and / or butyl (meth)acrylate, such as n-butyl acrylate and / or tert-butyl (meth)acrylate.

5. The method according to any one of claims 1 to 4, wherein the adsorbent material (6) comprises activated carbon and / or alumina.

6. The method according to any one of claims 1 to 5, wherein the product mixture (2) is contacted with the adsorbent material (6) at a temperature of 0°C to 50°C, particularly 5°C to 40°C.

7. The method according to any one of claims 1 to 6, wherein the concentration of phenothiazine in the product mixture is in the range of 0.1 ppm by weight to 100.0 ppm by weight, particularly 0.1 ppm by weight to 10.0 ppm by weight, relative to the total product mixture (2).

8. The method according to any one of claims 1 to 7, wherein the concentration of phenothiazine in the product composition is 1.0 ppm by weight or less, particularly less than 0.7 ppm by weight, relative to the total product composition (8).

9. The method according to any one of claims 1 to 8, wherein the concentration of the phenothiazine in the product composition (8) based on the total product composition (8) is lower than the concentration of the phenothiazine in the product mixture (2) based on the total product mixture (2).

10. The method according to any one of claims 1 to 9, wherein the product mixture (2) is contacted with the adsorbent material (6) in a continuous mode, and the adsorbent material (6) is arranged as a fixed bed or slurry.

11. The method according to claim 10, wherein the ratio between the adsorbent material (6) and the product mixture (2) is in the range of 0.01% by weight to 20.00% by weight.

12. The method according to claim 10, wherein the flow rate of the product mixture (2) is in the range of 0.10 adsorbent material (6) bed volume / hour (BV / h) to 3.00 BV / h.

13. A product composition (8) obtainable by the method according to any one of claims 1 to 12, said product composition comprising, relative to the total product composition (8), at least 95% by weight, particularly at least 98% by weight, of C1 to C2. 22 - (meth)acrylate and 1 wt ppm or less of phenothiazine, and optionally 2 wt ppm to 50 wt ppm of 4-methoxyphenol.

14. A polymer based on a product composition (8) that can be obtained by any one of claims 1 to 12 or a product composition (8) according to claim 13.

15. A method for producing a polymer, the method comprising the following steps: The product composition (8) that can be obtained by any one of claims 1 to 12 or the product composition (8) according to claim 13 is polymerized by emulsion polymerization in an aqueous reaction medium, by solution polymerization, by suspension polymerization or by bulk polymerization.

16. Use of the product composition (8) obtainable by any one of claims 1 to 12 or the product composition (8) according to claim 13 for the preparation of adhesives and / or coatings, particularly adhesives and / or coatings capable of UV curing.

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