Polymer raw materials with reduced reactivity of storage-stable reactive resins

Abstract

The field of the invention is the production of reactive resins, especially (meth)acrylate resins, which are used as components of two-component systems, for example, as road markings, floor coatings or sealants, where a particular feature of the novel process is that its use can improve the safety and stability of the products both during production and during storage and transport.

Description

[Technical Field]

[0001] The field of the invention is the production of reactive resins, especially (meth)acrylate resins, which are used as components of two-component systems, for example, as road markings, floor coatings or sealants, where a particular feature of the novel process is that its use can improve the safety and stability of the products both during production and during storage and transport.

[0002] prior art A large number of (meth)acrylate resins based on different concepts are known from the prior art, which can be used in a wide variety of application areas, such as road markings, floor coatings, roof or bridge coatings, metal coatings, e.g., anti-corrosion or flame-retardant coatings, as well as adhesives and sealants.

[0003] (Meth)acrylate resins are understood to be solutions of (meth)acrylic acid ester monomers in polymers such as poly(meth)acrylates. These resins generally contain further additives and auxiliaries. One important component is the so-called activator, also known as accelerator. These components trigger the polymerization of the monomer moieties in the (meth)acrylate resin when an initiator, such as a peroxide, is added. The addition of the initiator to harden the (meth)acrylate resin is carried out, for example, directly at the application site, e.g., at the construction site.

[0004] (Meth)acrylate resin components are generally not used immediately after production, so they must have sufficient storage stability over relatively long periods of time. For this reason, they are often transported long distances after production, even as intercontinental sea freight. Maximizing the storage stability of (meth)acrylate resins, especially at high temperatures, is important not only from a quality perspective but also from a safety perspective. Furthermore, such storage-stable (meth)acrylate resins can eliminate costly temperature-controlled shipping and temperature-controlled storage. Therefore, uncontrolled polymerization during production, shipping, or storage must be avoided.

[0005] (Meth)acrylate resins are typically produced in chemical plants by dissolving a polymer, such as a (meth)acrylate polymer, in a (meth)acrylate monomer mixture and optionally mixing it with additives, accelerators, and other additives. The polymer dissolution process and mixing with additional feedstocks are typically carried out at temperatures between 40 and 70°C. Preferably, suspension polymers, also known as polymer pellets or, more preferably, bead polymers, are used in the production of reactive resins. The advantage of suspension polymers is that they generally have small particle sizes, typically less than 0.8 mm. This ensures rapid dissolution of these small particles into the (meth)acrylate monomer mixture. Solid bulk polymers, such as pellets, must first be prepared through a complex grinding process before they can be used in the production of reactive resins.

[0006] Short-chain (meth)acrylic esters, such as methyl methacrylate, are highly flammable and have sufficient vapor pressure to form explosive atmospheres even at low temperatures. Therefore, in practice, production tanks for (meth)acrylate resins are blanketed with oxygen-depleted air or even pure protective gases, such as nitrogen. However, an atmosphere with a low oxygen content adversely affects the stability of reactive resins. Oxygen inhibits the polymerization of (meth)acrylic esters because the addition of oxygen to the radical chain ends occurs at a faster rate than the addition of monomers.

[0007] The (meth)acrylate polymers used in the preparation of reactive resins are prepared by separate suspension or bulk polymerization processes. In these processes, monomers are polymerized under controlled conditions using peroxides as initiators. Regarding bulk polymerization, Houben-Weyl, Band E20, Teil 2 (1987), pp. 1145ff. provides a useful reference. Regarding suspension polymerization, see pages 1149 and following of this document.

[0008] Residual peroxides are generally still present in the suspension or bulk polymers produced. This residual content depends greatly on the peroxide used, the temperature level, and the residence time at the corresponding temperature in the corresponding production process. Peroxide residues are particularly important with respect to production, transportation, and storage; peroxides have a half-life of, for example, one hour within a temperature range of 70-100°C. These peroxides can lead to uncontrolled polymerization during the production of reactive resins at high temperatures, for example, 40-70°C. Furthermore, during transportation and storage, these peroxide residues decompose over time to form radicals, which can also lead to uncontrolled polymerization.

[0009] U.S. Patent No. 2,833,753 discloses that the residual peroxide content of commercially available acrylic polymers is usually not sufficient to induce polymerization of added monomers at low temperatures, e.g., below 50° C. However, there is no mention of the residual peroxide content typically present in commercial products, and experience shows that there is still a risk of residual peroxide.

[0010] German Patent Application No. 19706064 also discloses that commercially available PMMA powders or suspension polymers may still have a residual content of active peroxide groups. This residual content is shown, in this case using the example of dibenzoyl peroxide, to be in the range of 0.24 to 45 mg / g. This corresponds to 0.99 to 186 mmol / kg of peroxide in the polymer, as determined by iodometric titration. Again, no adverse effects on the storage stability of monomer / polymer mixtures containing this residual content are expected.

[0011] In the production of suspension polymers, the temperature level during polymerization according to the prior art of DE 102009027620 A1, using the example of initiation with lauroyl peroxide, is 65-90°C. After the actual polymerization is completed with a conversion of more than 99% of the monomers used, the polymer is separated from the suspension and then dried in a drying process, for example, in a fluidized bed. In practice, such polymers still contain residual peroxide content from the production, which may represent a significant residual risk of undesired polymerization during the production of reactive resins, especially when used in inerting mixing tanks.

[0012] In summary, even if several documents of the prior art have concluded that the risk that peroxide residues in suspension polymers pose to the storage of (meth)acrylate-based reactive resins is extremely low, it can be clearly stated that in practice even this minimal risk can inevitably lead to defective batches and to products that are no longer usable after storage.

[0013] assignment In view of this prior art and practical experience, the object of the present invention was therefore to further minimize the residual risk of undesired polymerization in the production of (meth)acrylate resins, and particularly when using polymer raw materials containing residual peroxides during transportation and storage. In particular, the object was to suppress, even partially, undesired polymerization when producing resins at high temperatures, due to explosion-proof requirements in a low-oxygen gas phase or in an inert gas atmosphere.

[0014] A further object was to avoid such polymerization of the reactive resins when the individual components of the reactive resins are stored and / or transported at potentially high temperatures.The present invention was therefore based in particular on the object of providing novel (meth)acrylate-based reactive resins which can be produced with uniform quality and without the risk of premature polymerization, even when high explosion protection requirements are met, and which likewise have high storage stability after production, even at high temperatures.

[0015] Other problems not explicitly stated may become apparent from the prior art, the detailed description, the examples, or the overall context of this application.

[0016] solution These problems have been solved by providing a novel method for producing storage-stable (meth)acrylate-based reactive resins. In this method, at least one polymer component and a monomer component are mixed together under stirring in a gas phase, with at least 90% by weight, preferably at least 99% by weight, of the polymer component being dissolved in the monomer component. The method is characterized in that the gas phase has an oxygen content of 3 to 8% by volume. Furthermore, in this method, the polymer component before being mixed with the monomer component has a residual peroxide content of at most 0.375 mmol, preferably at most 0.25 mmol, of peroxide per kg.

[0017] The maximum amount of peroxide, for example in the case of lauroyl peroxide, corresponds to, for example, preferably a maximum of about 150 ppm by weight, particularly preferably a maximum of about 100 ppm by weight of lauroyl peroxide. Surprisingly, even at this low peroxide content, particularly storage-stable reactive resins can be produced.

[0018] It has been found that the peroxide content can be reduced during polymer production by a post-heating step, which follows the actual polymerization and is carried out at the same or advantageously higher temperature than the actual polymerization process, thereby reducing the residual amount of peroxide to less than 0.375 mmol / kg polymer.

[0019] For example, in bead polymerization using lauroyl peroxide as initiator (1-hour half-life temperature = 79°C, where 50% of the initiator decomposes within 1 hour), the suspension before drying is advantageously heated to a temperature at least 8°C above the 1-hour half-life temperature and maintained at this temperature level for at least 90 minutes. This reduces the residual peroxide content in the polymer to a maximum of 0.375 mmol / kg or 150 ppm lauroyl peroxide. If the post-heating step is carried out at a temperature at least 11°C above the 1-hour half-life temperature of the initiator for at least 60 minutes or at least 90 minutes, the residual peroxide content is reduced to a maximum of 150 ppm or 100 ppm lauroyl peroxide.

[0020] Similarly, in the less preferred bulk polymerization, an additional post-heating step can be carried out after the actual polymerization reaction. In this case, the residual peroxide present is reduced by heat treatment to a maximum of 0.375 mmol / kg polymer. The post-heating is likewise carried out at the same temperature as the polymerization or, advantageously, at a higher temperature.

[0021] With regard to the gas phase, there are many ways to achieve the oxygen content set by the present invention. For example, a protective gas such as nitrogen or argon can be mixed with an appropriate amount of pure oxygen. Preferably, however, air is introduced together with the protective gas to achieve the appropriate oxygen concentration. When nitrogen is supplied, a gas composition containing at least 90% by volume of nitrogen is achieved. When argon is used as the protective gas, the gas phase contains at least 12% by volume of argon.

[0022] In a further, less preferred alternative, CO2 can be supplied to the reactor or added as dry ice, in which case the gas phase contains at least 12% carbon dioxide by volume.

[0023] Preferably, the polymer component used is a poly(meth)acrylate. Particularly preferably, the polymer used is a suspension polymer.

[0024] Here, it has proven advantageous if the suspension polymer is initiated with lauroyl peroxide during manufacture, although other peroxides may also be used, particularly those with a similar combination of decomposition temperature and decomposition time.

[0025] The monomer component is preferably a methacrylate, an acrylate, or a mixture of methacrylate and / or acrylate. Here, the term (meth)acrylate, which is frequently used in the present invention, is an abbreviation for methacrylate, acrylate, or a mixture of methacrylate and / or acrylate. The same applies to the term poly(meth)acrylate.

[0026] Monomers present in the reactive resins are, in particular, alkyl (meth)acrylates of linear, branched or alicyclic alcohols having, for example, 1 to 40 carbon atoms, such as methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, stearyl (meth)acrylate, lauryl (meth)acrylate; aryl (meth)acrylates, such as benzyl (meth)acrylate; ethers having 5 to 80 carbon atoms, polyethylene glycol, polypropylene glycol. or a mixture thereof, such as a mono(meth)acrylate, for example, a compound selected from the (meth)acrylate group, such as tetrahydrofurfuryl (meth)acrylate, methoxy(meth)ethoxyethyl (meth)acrylate, benzyloxymethyl (meth)acrylate, 1-ethoxybutyl (meth)acrylate, 1-ethoxyethyl (meth)acrylate, ethoxymethyl (meth)acrylate, poly(ethylene glycol) methyl ether (meth)acrylate, and poly(propylene glycol) methyl ether (meth)acrylate.

[0027] In addition to these (meth)acrylates, the monomer component may also contain further unsaturated monomers copolymerizable with the above (meth)acrylates by radical polymerization. These include, in particular, 1-alkenes or styrene. In particular, the proportions and composition of the poly(meth)acrylates are selected to be advantageous in terms of the desired technical function.

[0028] As constituents of the monomer component, additional monomers having further functional groups are also suitable, such as α,β-unsaturated mono- or dicarboxylic acids, such as acrylic acid, methacrylic acid, or itaconic acid; esters of acrylic acid or methacrylic acid with dihydric alcohols, such as hydroxyethyl (meth)acrylate or hydroxypropyl (meth)acrylate; acrylamide or methacrylamide; or dimethylaminoethyl (meth)acrylate. Further suitable components of the monomer mixture are, for example, glycidyl (meth)acrylate or silyl-functional (meth)acrylate.

[0029] Preferably, the polymer and monomer components used according to the invention contain a maximum of 5% by weight of acrylate groups and acrylate repeat units, based on the total of acrylate and methacrylate groups. The mixture is particularly preferably completely free of acrylate groups and acrylate repeat units.

[0030] The polymeric components may have additional functional groups, for example in the form of hydroxy groups, for adhesion promotion, or for copolymerization in an optional crosslinking reaction, for example in the form of double bonds, but preferably the polymeric components do not have double bonds.

[0031] Particularly preferably, upon mixing, there is a composition having the following components: 0% to 30% by weight of crosslinking agent, 20% to 85% by weight of a monomer composition; 0% to 60% by weight of urethane (meth)acrylate, 10% to 40% by weight of a polymer composition; 0% to 5% by weight of auxiliary substances, including one or more substances selected from paraffins, additives, stabilizers, pigments, dyes and / or auxiliaries; and 0 wt% accelerator, for example at least 1.5 wt% to 10 wt%.

[0032] If a crosslinking agent is present, it is preferably used at a minimum concentration of 0.5% by weight.

[0033] In this case, a composition comprising the following ingredients is particularly preferred: - 1.0% to 20% by weight, particularly preferably 1.5% to 15% by weight, of a crosslinker, preferably a polyfunctional (meth)acrylate, very particularly preferably a di-, tri- or tetra(meth)acrylate, - 25% to 75% by weight, particularly preferably 30% to 40% by weight, of (meth)acrylates and / or monomers copolymerizable with (meth)acrylates, - 0% to 45% by weight, particularly preferably up to 30% by weight, of urethane (meth)acrylates, 10% to 35% by weight, particularly preferably 15% to 25% by weight, of poly(meth)acrylates, optionally further auxiliaries, - 0.5% to 5% by weight, particularly preferably 2% to 4% by weight, of accelerators.

[0034] The accelerator is preferably a tertiary amine or a tertiary organic phosphite. Here, the tertiary amine is generally a symmetrical tertiary aromatic amine, as known in the prior art. Such symmetrical tertiary aromatic amines include, for example, N,N-dimethyl-p-toluidine, N,N-bis(2-hydroxyethyl)-p-toluidine, or N,N-bis(2-hydroxypropyl)-p-toluidine.

[0035] An optional component of the reactive resin according to the present invention is a crosslinker. In particular, a polyfunctional (meth)acrylate such as allyl (meth)acrylate is preferred. Particularly preferred are di- or tri(meth)acrylates such as butane-1,4-diol di(meth)acrylate, poly(urethane) (meth)acrylate, tetraethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, or trimethylolpropane tri(meth)acrylate.

[0036] Optional urethane (meth)acrylates are understood in the present invention to mean compounds having (meth)acrylate functional groups bonded to each other via urethane groups. These can be obtained by reacting hydroxyalkyl (meth)acrylates with polyisocyanates and polyoxyalkylenes having at least two hydroxyl functional groups. Instead of hydroxyalkyl (meth)acrylates, esters of (meth)acrylic acid with oxiranes, such as ethylene oxide or propylene oxide, or the corresponding oligo- or polyoxiranes, can also be used. For example, an overview of urethane (meth)acrylates with more than two functional groups is given in German Patent Application Publication No. 19902685. An example of a commercially available urethane (meth)acrylate made from polyols, isocyanates, and hydroxy-functional (meth)acrylates is EBECRYL 210-5129 from Allnex. In reactive resins, urethane (meth)acrylates increase flexibility, breaking strength, and breaking elongation without significant temperature dependence. Surprisingly, it was found that even urethane acrylates can be successfully cured tack-free at relatively high weight ratios using a novel curing system, opening up the possibility of producing flexible reactive resins, such as those required for road markings and sealing systems, with minimal use of acrylate monomers, which typically have low glass transition temperatures.

[0037] As is known from the technical field of reactive resins, in particular (meth)acrylate resins, also in the process according to the invention it is possible to additionally mix the polymeric and monomeric components with additives and / or auxiliaries, in particular paraffins, additives, stabilizers and inhibitors, pigments, dyes and / or auxiliaries.

[0038] Additives or auxiliaries are understood here to mean, inter alia, modifiers, plasticizers, stabilizers and inhibitors, waxes and / or oils, as well as defoamers, rheological additives, wetting aids, dispersing aids, and leveling aids. Paraffins are added to prevent polymerization inhibition by atmospheric oxygen. For this purpose, paraffins with different melting points can be used in different concentrations. It has proven highly advantageous for the two-component reactive resins of the present invention to further contain one or more paraffins in an amount of 0.3 to 3% by weight. These paraffins are characterized by a freezing point according to DIN-ISO 2207 in the temperature range of 35 to 75°C.

[0039] As the regulator, all compounds known from radical polymerization can be used. Preferably, mercaptans such as n-dodecyl mercaptan are used. As the plasticizer, advantageously, esters, polyols, oils, low molecular weight polyethers or phthalates are used.

[0040] As wetting aids, dispersing aids and levelling aids, those selected from the group of alcohols, hydrocarbons, glycol derivatives, glycolic acid ester derivatives, acetic acid ester derivatives and polysiloxane derivatives, polyethers, polysiloxanes, polycarboxylic acids, saturated and unsaturated polycarboxylic acid amine amides are preferably used.

[0041] As rheological additives, advantageously used are polyhydroxycarboxylic acid amides, urea derivatives, salts of unsaturated carboxylic acid esters, alkylammonium salts of acidic phosphoric acid derivatives, ketoximes, amine salts of p-toluenesulfonic acid, amine salts of sulfonic acid derivatives, and aqueous or organic solutions or mixtures of compounds.As defoamers, advantageously used are those selected from the group consisting of alcohols, hydrocarbons, paraffinic mineral oils, glycol derivatives, glycolic acid ester derivatives, acetic acid ester derivatives and polysiloxane derivatives.

[0042] UV stabilizers can also be used. Advantageously, UV stabilizers are selected from the group consisting of benzophenone derivatives, benzotriazole derivatives, thioxanthate derivatives, piperidinol carboxylic acid ester derivatives, and cinnamic acid ester derivatives. From the group of stabilizers or inhibitors, preferred are substituted phenols, hydroquinone derivatives, and stabilized radicals, such as 4-hydroxy-2,2,6,6-tetramethylpiperidinyloxyl (TEMPOL). In practice, there is an upper limit to the amount of additives that can be reasonably used in reactive resins, because otherwise, incomplete curing occurs during intentional curing, especially at low temperatures. A combination of several different stabilizers can also be used in reactive resins, with a preferred combination being a substituted phenol, preferably at a concentration of 100 to 1000 ppm, and a stabilized radical, such as TEMPOL, preferably at a concentration of 15 to 150 ppm.

[0043] It has proven to be very advantageous for some applications if the product of the process according to the invention further comprises 0.3% to 3% by weight of one or more paraffins, wherein these paraffins are characterized by a freezing point according to DIN-ISO 2207 in the temperature range from 35°C to 75°C.

[0044] For various fields of use of the reactive resins produced according to the invention, for example as road markings, in particular as lines, bars or symbols, or as surface markings for identifying, for example, bicycle paths or bus lanes or parking spaces, dyes are advantageously added as auxiliary and additive substances. Particularly preferred are white, red, blue, green and yellow inorganic pigments, and particularly preferred are white pigments such as titanium dioxide.

[0045] The reactive resins produced according to the invention can be used in a wide range of technical fields, for example road markings, floor coverings, preferably for industrial use, for the production of cast parts, for sealing or coating roofs, bridges or their joints, in particular as sealing membranes, for bridge coatings in general, as roof sealing membranes, for the production of panels, for further use, for example, as worktops, in particular for the production of protective coatings for metal surfaces, as resins for drainage systems, for the production of sanitary articles, for the production of adhesives, for example for filling cracks in buildings, or for use in the orthopedic field.

[0046] Example The present invention will be described in more detail below using comparative examples and selected example embodiments.

[0047] The residual peroxide content of the polymer was determined by high performance liquid chromatography (HPLC).

[0048] Sample preparation: 2.0 g of (meth)acrylate polymer was completely dissolved in 5.0 mL of dichloromethane at room temperature. Then, 70 mL of n-hexane was added to precipitate the (meth)acrylate polymer again. After filtration, the filtrate was dried under reduced pressure. The remaining residue was taken up in cyclohexane and analyzed by HPLC.

[0049] Chemically modified silica gel was used as the stationary phase for HPLC (C18 column). Detection was performed using a UV-VIS detector (220 nm). Calibration and validation of the HPLC were performed using a lauroyl peroxide / cyclohexane standard solution (external standard).

[0050] Production of bead polymers with controlled residual peroxide content To prepare the bead polymer, a Pickering stabilizer solution of aluminum hydroxide was first prepared as described in EP 1219642 (Example 1). A 5-L glass reactor equipped with an Inter-MIG stirrer and reflux condenser was charged with 3200 mL of the Pickering stabilizer solution. The stirrer was set at 300 rpm and heated to a jacket temperature of 40°C. In a glass beaker, 960 g (60 wt%) of n-butyl methacrylate, 640 g (40 wt%) of methyl methacrylate, 8.0 g of lauroyl peroxide, and 12.30 g of 2-ethylhexyl thioglycolate were mixed and homogenized with stirring. This monomer stock solution was pumped into the reactor and polymerized for 110 minutes (polymerization time) with stirring at an internal reactor temperature of 76°C (polymerization temperature). After polymerization, the resulting suspension polymer was thermally post-treated as shown in the table below. Depending on the length of time and temperature level of the thermal post-treatment, different residual contents of lauroyl peroxide in the bead polymer could be adjusted.

[0051] [Table 1]

[0052] Each batch was then cooled to 45°C, and the stabilizer was converted to water-soluble aluminum sulfate by the addition of 50% sulfuric acid. The mother liquor was separated from the polymer beads using a Nutsche filter, washed with demineralized water, and dried in a fluidized bed dryer at an inlet air temperature of 70°C until the residual moisture content was about 0.5% by weight.

[0053] Comparative Example 1 A 2000 mL double-jacketed glass reactor equipped with a reflux condenser and a mechanical stirrer (anchor type), and having multiple inlets and gas inlets, was charged with 515.1 g of methyl methacrylate (stabilized with 5 ppm of 2,6-di-tert-butyl-4-methylphenol), 510.0 g of n-butyl acrylate (stabilized with 5 ppm of 2,6-di-tert-butyl-4-methylphenol), 40.0 g of triethylene glycol dimethacrylate (stabilized with 250 ppm of 2,6-di-tert-butyl-4-methylphenol), 0.900 g of 2,6-di-tert-butyl-4-methylphenol, 20.0 g of Sasolwax 5603 (olefin wax), and 14.0 g of N,N-bis(2-hydroxypropyl)-p-toluidine, and the mixture was stirred. The reactor was then purged and blanketed with a gas mixture consisting of 96% nitrogen and 4% oxygen. Then, 400.0 g of bead polymer with a specific residual content of 200 ppm by weight of lauroyl peroxide, corresponding to 0.50 mmol of lauroyl peroxide per kg of bead polymer, was added with vigorous stirring. The double jacket was then heated with 60°C hot water until the temperature of the added components reached 55°C. Stirring was continued until all components were dissolved, which occurred approximately 75 minutes after the addition of the bead polymer. The resin was then cooled to 23°C with stirring.

[0054] Example 1 A 2000 mL double-jacketed glass reactor equipped with a reflux condenser and a mechanical stirrer (anchor type), and having multiple inlets and gas inlets, was charged with 515.1 g of methyl methacrylate (stabilized with 5 ppm of 2,6-di-tert-butyl-4-methylphenol), 510.0 g of n-butyl acrylate (stabilized with 5 ppm of 2,6-di-tert-butyl-4-methylphenol), 40.0 g of triethylene glycol dimethacrylate (stabilized with 250 ppm of 2,6-di-tert-butyl-4-methylphenol), 0.900 g of 2,6-di-tert-butyl-4-methylphenol, 20.0 g of Sasolwax 5603 (olefin wax), and 14.0 g of N,N-bis(2-hydroxypropyl)-p-toluidine, and the mixture was stirred. The reactor was then purged and blanketed with a mixture of 96% nitrogen and 4% oxygen.

[0055] Then, 400.0 g of bead polymer with a specific residual content of 80 ppm by weight of lauroyl peroxide, corresponding to 0.20 mmol of lauroyl peroxide per kg of bead polymer, was added with vigorous stirring. The double-jacket was then heated with 60°C hot water until the temperature of the added components reached 55°C. Stirring was continued until all components were dissolved, which occurred approximately 75 minutes after the addition of the bead polymer. The resin was then cooled to 23°C with stirring.

[0056] Comparison of storage stability at 90°C of the resins obtained in Example 1 and Comparative Example 1 To test the storage stability, 90 mL of each prepared methacrylate resin was filled into a 100 mL glass bottle. The bottle was closed and stored in a heating cabinet at 90°C. The stability of the methacrylate resin was visually inspected several times a day.

[0057] [Table 2]

[0058] Comparing these results, it is clear even with the naked eye that Example 1 according to the present invention has a much higher storage stability.

[0059] Comparative Example 2 A 2000 mL double-jacketed glass reactor equipped with a reflux condenser, anchor-type mechanical stirrer, and multiple inlets and gas inlets was charged with 515.1 g of methyl methacrylate (stabilized with 5 ppm of 2,6-di-tert-butyl-4-methylphenol), 510.0 g of n-butyl acrylate (stabilized with 5 ppm of 2,6-di-tert-butyl-4-methylphenol), 40.0 g of triethylene glycol dimethacrylate (stabilized with 250 ppm of 2,6-di-tert-butyl-4-methylphenol), 0.900 g of 2,6-di-tert-butyl-4-methylphenol, 20.0 g of Sasolwax 5603 (olefin wax), and 14.0 g of N,N-bis(2-hydroxypropyl)-p-toluidine, and the mixture was stirred. The reactor was then purged and blanketed with nitrogen. After this, 400.0 g of bead polymer having a specific residual content of 250 ppm by weight of lauroyl peroxide, corresponding to 0.63 mmol of lauroyl peroxide per kg of bead polymer, was added with vigorous stirring. The double jacket was then heated with hot water at 60° C. until the temperature of the added components rose to 55° C. After 45 minutes of stirring had elapsed after the addition of the bead polymer, polymerization of the reactor contents occurred, which was evident, in particular, from a strong increase in viscosity due to the formation of a gel-like component.

[0060] Comparative Example 3 A 2000 mL double-jacketed glass reactor equipped with a reflux condenser, anchor-type mechanical stirrer, and multiple inlets and gas inlets was charged with 515.1 g of methyl methacrylate (stabilized with 5 ppm of 2,6-di-tert-butyl-4-methylphenol), 510.0 g of n-butyl acrylate (stabilized with 5 ppm of 2,6-di-tert-butyl-4-methylphenol), 40.0 g of triethylene glycol dimethacrylate (stabilized with 250 ppm of 2,6-di-tert-butyl-4-methylphenol), 0.900 g of 2,6-di-tert-butyl-4-methylphenol, 20.0 g of Sasolwax 5603 (olefin wax), and 14.0 g of N,N-bis(2-hydroxypropyl)-p-toluidine, and the mixture was stirred. The reactor was then purged and blanketed with nitrogen. Then, 400.0 g of bead polymer having a specific residual content of 80 ppm by weight of lauroyl peroxide, corresponding to 0.20 mmol of lauroyl peroxide per kg of bead polymer, was added thereto with vigorous stirring. The double jacket was then heated with hot water at 60° C. until the temperature of the added components rose to 55° C. After 120 minutes of stirring had elapsed after the addition of the bead polymer, polymerization of the reactor contents occurred, which was evident, in particular, from a strong increase in viscosity due to the formation of a gel-like component.

[0061] [Table 3]

[0062] Comparing these results, it can be seen that the time to polymerization was much longer when the resin was prepared under nitrogen in Comparative Example 3. Nevertheless, it shows that a minimum proportion of oxygen is important when preparing reactive resins.

Claims

1. 1. A method for producing a storage-stable (meth)acrylate-based reactive resin, comprising mixing at least one polymer component and a monomer component with one another under stirring in a gas phase, wherein at least 90% by weight of the polymer component is dissolved in the monomer component, characterized in that the gas phase has an oxygen content of 3 to 8% by volume, and the polymer component prior to mixing with the monomer component has a residual peroxide content of at most 0.375 mmol of peroxide per kg.

2. 2. The method of claim 1, wherein the residual peroxide content in the polymer components prior to the mixing is at most 0.25 mmol of peroxide per kg of polymer.

3. 3. The method according to claim 1, wherein the polymer component used is a poly(meth)acrylate.

4. 4. The process according to claim 1, wherein the polymer used is a suspension polymer.

5. 5. The method of claim 4, wherein the suspension polymer is initiated with lauroyl peroxide during manufacture.

6. 6. The method according to claim 1, wherein the monomer component is a methacrylate, an acrylate, or a mixture of methacrylates and / or acrylates.

7. 7. The method according to claim 1, further comprising mixing the polymeric and monomeric components with paraffins, modifiers, plasticizers, inhibitors, waxes, oils, defoamers, rheological additives, stabilizers, pigments, dyes, wetting aids, dispersing aids and / or leveling aids.

8. 8. The method according to claim 1, wherein the gas phase comprises at least 90% by volume of nitrogen.

9. 8. The method according to claim 1, wherein the gas phase comprises at least 12% by volume of argon and / or carbon dioxide.

10. 10. The method of claim 1, wherein the polymeric and monomeric components contain up to 5% by weight of acrylate groups and acrylate repeat units, based on the total of acrylate and methacrylate groups.

11. During the mixing, 0% to 30% by weight of a crosslinker; 20% to 85% by weight of a monomer component, 0% to 60% by weight of urethane (meth)acrylate, 10% to 40% by weight of a polymer component; 0% to 5% by weight of auxiliary substances, including one or more substances selected from paraffins, modifiers, plasticizers, inhibitors, waxes, oils, defoamers, rheological additives, stabilizers, pigments, dyes, wetting aids, dispersing aids and / or leveling aids, and Accelerators 0% to 10% by weight 11. The method according to claim 1, wherein a composition is present comprising:

12. 12. The method of claim 11, wherein the accelerator is a tertiary amine or a tertiary organic phosphite.

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