Use of polyether siloxanes as processing aids for melt granulation

Abstract

The invention relates to the use of polyether siloxanes with less than 20 silicon atoms as a parting agent or parting agent constituent in melt granulation, a process for producing melt granules using these polyether siloxanes, and melt granules which are obtained by the use or by the process according to the invention.

Description

[0001] Use of polyethersiloxanes as processing aids for melt granulation

[0002] The present invention is in the field of melt granulation. In particular, the invention relates to the use of polyether siloxanes containing fewer than 20 silicon atoms as release agents or release agent components in melt granulation, a process for producing melt granules using these polyether siloxanes, and melt granules obtainable by this use or by this process.

[0003] Melts are produced in many chemical industrial processes. For example, liquid sulfur is produced in large quantities in refineries using the Claus process. Various processes are available today that convert the liquid melt into a manageable, solid form. The molten products are fed into a feed device and shaped into suitable forms such as spheres, flakes, pellets, or other shapes, preferably uniform shapes, preferably uniform and as spherical as possible (cooling belt systems). In these often continuous processes, the industry pays particular attention to the cleanliness of the conveying equipment, which is preferably steel conveyor belts, and to good separation of the shaped bodies from the conveying equipment to ensure the process can run continuously over time. Furthermore, good product dosing and cost-effective, clean product packaging are required.In particular, consistent shape and size of the molded bodies, which requires good separation of the products from the conveyor belts, is important for subsequent transport and precise dosing. If the shape of the melt granules has sharp edges, they can break and generate dust, particularly during sulfur pelletizing. Furthermore, such bodies are undesirable because they cannot be precisely dosed in subsequent processes.

[0004] Steel belt coolers are a frequently used technology for this type of melt solidification. The melt is continuously cooled and solidified. Different technologies allow for the formation of a wide variety of shapes of a specific size. Perforated plates are an older technology. In this case, a sulfur melt from the Claus process is fed through one or more perforated plates into a water-filled prill tank. Corresponding processes for the production of sulfur granules are described, for example, in US Pat. No. 3,637,351 and EP 0064311 A1.

[0005] DE 2928401 A1 also describes a process for granulating sulfur, in which molten sulfur is applied to a metal support and cooled until solidification occurs, wherein, before the molten sulfur is applied to the metal support, a composition comprising solvent, organic titanate and a liquid carboxyfunctional siloxane is applied.

[0006] A technology that is now widely used is the solidification of sulfur melts using a steel belt cooler and the so-called Rotoformer® (Rotoform system), as offered by IPCO (formerly Sandvik Process Systems), for example. The molten sulfur is fed to a Rotoformer® at a temperature of 125°C to 145°C and is then evenly distributed in droplet form onto a steel belt, the underside of which is cooled by water, for example using spray nozzles, or passed through a water bath. In this process, too, great care is taken to ensure good separation of the shaped bodies and a uniform, preferably spherical shape of the molten granules. The principle of these processes is described, for example, in US 6398989 and US 4279579.

[0007] Particularly when granulating sulfur using the various processes for producing certain hot-melt granules, such as pastilles, release agents must be used to prevent them from sticking to steel belts or other conveying equipment. The release agents also have a positive effect on the shape of the hot-melt granules, which improves subsequent packaging and reuse (precise dosing). One frequently used release agent is silicone oil. GB 1537888 describes the use of silicone oils with a viscosity of 20 cSt to 50 cSt from Dow Corning, for example. This fluid is sold under the trade name DOW CORNING® 200 FLUID, 20 cSt. The release agent is dispersed in the molten sulfur and simplifies pelletizing, which takes place on a cooled steel belt. A disadvantage of this technology is that the silicone oil has to be dispersed into the sulfur.Since silicone oil is completely incompatible with the water used to cool and clean the steel belts, this leads to contamination and greasy residues in the system, which negatively impact the separation of the molded bodies from the steel belt cooler. An improvement has been achieved with the use of silicone oil emulsions. Applying the emulsion by spraying or dipping the steel belts facilitates the process; however, adhering silicone residues on the belts cannot be re-emulsified and therefore lead to contamination. A further disadvantage of the emulsions is their low stability. Separation of the silicone oil from the aqueous phase often occurs as low as 35°C, which complicates their use in refineries in warm countries, as the silicone oil often separates in the storage or reservoir tanks or in conveyor systems.

[0008] The disadvantages described above could be reduced by using polyether siloxanes, as polyether siloxanes are more hydrophilic than silicone oils. A frequently used polyether siloxane for melt granulation is Tegopren® 5863 (Evonik). It has a polysiloxane chain with 48 silicon atoms and carries two polyethers of different molecular weights on the siloxane chain, both of which, however, have the same mass fraction of ethylene oxide (approx. 40%) and propylene oxide (approx. 60%). This polyether siloxane is water-soluble and is applied as an aqueous solution. The disadvantages of emulsion stability at higher temperatures are eliminated. One disadvantage, however, is that the good separation of the melt granules does not remain constant but decreases over time. Furthermore, the shape of the melt granules can deviate slightly from the optimal spherical shape.Curved melt granules are obtained, of which flatter moldings cause the described problems of breakage of the thinner edges and dosing problems. Since the melt granules must be handled after production (e.g., during transport, storage, and further processing), low dust generation and low susceptibility to breakage are preferred. A further disadvantage of this polyether siloxane is that two different polyethers must be used in its production, which is carried out by hydrosilylation from the corresponding unsaturated polyethers and an SiH-functional siloxane.

[0009] EP 2543630 A1 discloses polyether siloxanes that, when used as release agents or release agent components for melt granulation, deliver even better results than Tegopren® 5863 (Evonik). The polyether siloxanes described therein have a polysiloxane chain with at least 20 silicon atoms and carry three different polyethers on this polysiloxane chain. These polyether siloxanes lead to very easy separation of the melt granules, with the separation performance not deteriorating even after 5 minutes. Furthermore, when using these polyether siloxanes, no stubborn residues form on the equipment, e.g., on the cooling steel belt. Furthermore, the resulting melt granules have a uniform spherical shape. However, deviations from the desired spherical shape are possible, albeit only to a very small extent.A further disadvantage of these polyether siloxanes is that three different polyethers must be used in their production, which is carried out via hydrosilylation from the corresponding unsaturated polyethers and the corresponding SiH-functional siloxanes.

[0010] The object of the present invention was therefore to provide compounds for use as release agents or release agent components in melt granulation which overcome at least one disadvantage of the prior art.

[0011] Specifically, the object of the present invention was to provide compounds for use as release agents or release agent components in melt granulation, which are easy to prepare, ensure very good and permanent separation of the sulfur granules, are very water-soluble, lead to spherical melt granules without fragile edges and also do not form persistent residues on the equipment, in particular the cooling steel belt, which could negatively influence the separation or the process flow.

[0012] In particular, the object of the present invention was further to provide compounds for use as release agents or release agent components in melt granulation, which are made from fewer raw materials and are therefore easier to produce than the polyether siloxanes previously used for this purpose.

[0013] Surprisingly, it has now been found that the use of polyether siloxanes containing fewer than 20 silicon atoms as release agents or release agent components in melt granulation solves this problem.

[0014] These polyethersiloxanes adsorb onto the sulfur granules, thus ensuring excellent release of the melt granules, even though they contain fewer silicon atoms than the polyethersiloxanes previously used for this purpose. This is particularly surprising because it was previously assumed that only long-chain polysiloxanes with a high number of silicon atoms, such as the silicone oils described above or state-of-the-art polyethersiloxanes, would achieve sufficient release properties in melt granulation.

[0015] A first object of the present invention is therefore the use of at least one polyether siloxane having fewer than 20 silicon atoms as a release agent or release agent component in melt granulation.

[0016] A further subject matter of the present invention is accordingly also a process for producing melt granules, characterized in that the at least one polyether siloxane is used as a release agent or release agent component.

[0017] Yet another object of the invention are melt granules which are obtainable by the use according to the invention and / or by the process according to the invention.

[0018] Advantageous embodiments of the subject matter of the invention can be found in the claims, the examples, and the description. Furthermore, it is expressly pointed out that the disclosure of the subject matter of the present invention includes all combinations of individual features of the present or subsequent description of the invention and the patent claims. In particular, embodiments of one subject matter of the invention also apply mutatis mutandis to the embodiments of the other subject matter of the invention.

[0019] An advantage of the polyethersiloxanes to be used according to the invention compared to the polyethersiloxanes from EP 2543630 A1 or the polyethersiloxane Tegopren® 5863 is that they do not have to be prepared from different polyethers and are therefore easier to produce. The inventors have surprisingly discovered that such polyethersiloxanes, which have only a small number of silicon atoms, are suitable as release agents or release agent components in melt granulation even if they do not have different polyether radicals.

[0020] Without being bound by any theory, it is assumed that polyethersiloxanes with a higher number of silicon atoms, due to the associated strong hydrophobicity of the polysiloxane moiety, must carry special and also different polyether radicals as hydrophilic than hydrophilic counterparts in order to achieve a balanced hydrophilic-lipophilic balance (HLB).

[0021] The invention further has the advantage that the melt granules have a nearly perfect spherical shape and thus no edges or flat, fragile areas that could break during further processing or packaging. Dust and irregularly shaped particles are thus avoided, enabling a clean processing process and more precise dosing of the melt granules.

[0022] A further advantage of the invention is that the water solubility of the polyether siloxanes significantly simplifies the application and cleaning of the granulation equipment. The water solubility also allows the release agent to be applied to the steel belt in virtually any thickness by varying the concentration of the polyether siloxane in the aqueous solution and the amount of the solution applied to the steel belt as a release agent.

[0023] A further advantage of the invention is that when the polyether siloxanes are used as release agents or release agent components in the melt granulation, no residues remain on the steel belt.

[0024] The subject matters according to the invention are described below by way of example, without the invention being restricted to these exemplary embodiments. If ranges, formulas or classes of compounds are given below, these are intended to include not only the corresponding ranges or groups of compounds that are explicitly mentioned, but also all sub-ranges and sub-groups of compounds that can be obtained by removing individual values ​​(ranges) or compounds. If documents are cited within the scope of the present description, their content, particularly with regard to the facts in connection with which the document was cited, is intended to be fully included in the disclosure of the present invention. For compositions, the % data refer to the total composition unless otherwise stated. If data are given below in percent, these are data in weight unless otherwise stated.-%. Unless otherwise stated, any measured values ​​or material properties given below are measured at 25 °C and preferably at a pressure of 101325 Pa (standard pressure) and preferably at a relative humidity of 50%. The number-average molecular weight MN is determined by gel permeation chromatography (GPC) in accordance with DIN 55672:2016, preferably in accordance with DIN 55672-1:2016. Wherever molecules or molecular fragments have one or more stereocenters or can be differentiated into isomers due to symmetries or due to other effects, such as restricted rotation, all possible isomers are included in the present invention. Specific embodiments are defined below, so that features such as indices or structural components may be restricted by the embodiment.For all features not affected by the restriction, the remaining definitions remain valid. In the context of this invention, the word fragment "poly" encompasses not only compounds with at least 2 repeating units of one or more monomers in the molecule, but preferably also those compositions of compounds that have a molecular weight distribution and an average molecular weight of at least 200 g / mol. This definition takes into account the fact that in the field of technology considered, it is customary to refer to such compounds as polymers, even if they do not appear to satisfy a polymer definition analogous to OECD or REACH guidelines. The polyether siloxanes described in the context of the present invention can have various structural units multiple times. These repeating units can be both disordered, e.g.randomly distributed or ordered in these compounds. The repeating units identified by indices in the following formulas (I), (II), (III), (IV) and (V) can therefore be randomly or block-wise distributed, they can also be alternately distributed or form a gradient over the chain, if one exists, in particular they can also form all mixed forms in which groups of different distributions can follow one another. Every permutation of the repeating units is therefore included in the following formulas (I), (II), (III), (IV) and (V). The divalent units (OC2H3R. 3 ) in formulas (II) and (III) as well as [CH2CH(CH3)O] in formulas (IV) and (V) can be bonded differently to the neighboring groups or atoms. In formulas (II) and (III) (OC2H3R 3 ) each independently represents a radical of the form [CH2CH(R 3 )O] and / or the form [CH(R3 )CH2O], but preferably a radical of the form [CH2CH(R 3)O], Accordingly, [CFhCHfCHsJO] in formulas (IV) and (V) each independently represents a radical of the form [CH2CH(CH3)O] and / or the form [CH(CHs)CH2O], but preferably a radical of the formula [CH2CH(CHs)O]. The formulas (I), (II), (III), (IV) and (V) describe compounds that are made up of repeating units, such as repeating fragments, blocks or monomer units, and can have a molecular weight distribution. The frequency of the repeating units is indicated by indices. The indices a, b, c, d, c(1), c(2), c(3), c(4) used in the formulas can be both natural numbers >0 and non-rational numbers >0, in each case of course only within the defined ranges. In the first case, the indices refer to the frequency of the repeating units in an individual polymer, as is the case, for example,as part of a polymer mixture, and in the second case to the frequency of repeat units given as an arithmetic mean (number average) based on the totality of the polymers in a mixture. This is to take into account that polymers, due to their molar mass distribution, usually only exist in mixtures. In the latter case, the index numbers a, b, c, d, c(1), c(2), c(3), c(4) used and the value ranges of the stated indices are therefore understood as mean values ​​of the possible distribution of the structures actually present and / or their mixtures. The polyethersiloxanes to be used according to the invention are preferably in the form of equilibrated mixtures. Special embodiments can lead to the statistical distributions being restricted by the embodiment. For all ranges not affected by the restriction, the statistical distribution does not change.

[0025] The term “unsaturated” describes the presence of one or more carbon-carbon triple bonds and / or carbon-carbon double bonds that are not part of an aromatic ring.

[0026] The terms melt granulate, granules, pellets, and pastilles are understood as synonymous terms within the scope of the present invention. Briquettes are also understood as granules or granular material within the scope of the present invention. The terms melt granulation, melt granulation, melt pelletization, and melt pelleting are hereinafter referred to collectively as "melt granulation."

[0027] The terms polyethersiloxane, polyetherpolysiloxane, polyether-modified siloxane, and polyether-modified polysiloxane are understood as synonymous terms within the context of the present invention. As already explained in the introduction, the use according to the invention is characterized by the use of polyethersiloxanes with fewer than 20, preferably 3 to 5, in particular 3 to 4 silicon atoms as release agents or release agent components in melt granulation.

[0028] Thus, for example, it is preferred that the polyether siloxanes have at least 3 and at most 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18 or 19 silicon atoms, with a smaller number of silicon atoms being preferred over a larger number.

[0029] A polyethersiloxane is understood to be a compound which has organic radicals bonded to silicon atoms and structural units of the formula Si-O-Si, where "=" stands for the three remaining valences of the silicon atom in question and where at least one organic radical comprises a polyether radical. The polyethersiloxanes are preferably compounds which consist of units selected from the group consisting of M = [R SiOß], D = [R 1 2SiO2 / 2], T = [R 1 1 SiOs / 2] and optionally additionally have units of the formula Q = [SiO«], where R 1 represents a monovalent organic radical and at least one radical R 1 a monovalent polyether radical R 2 and all remaining residues R 1 monovalent hydrocarbon radicals R. The radicals R 1 or R and R 2can be selected independently of each other and are the same or different when compared pairwise.

[0030] It is further preferred that the at least one polyethersiloxane is a compound of formula (I), Formula (I); where:

[0031] R is each independently selected from the group consisting of monovalent hydrocarbon radicals having 1 to 10 carbon atoms, preferably each independently selected from the group consisting of methyl, ethyl, propyl and phenyl, in particular methyl;

[0032] R 1 is each independently selected from the group consisting of R and R 2 , preferably R, especially methyl;

[0033] R 2 is each independently selected from the group consisting of monovalent polyether radicals of the formula (II), -Z[(OC2H3R 3 )cOR 4 ]d formula (II);

[0034] Z is each independently selected from the group consisting of (d+1)-bonded hydrocarbon radicals having 2 to 10, preferably 3 to 4, in particular 3, carbon atoms, optionally interrupted by oxygen atoms;

[0035] R 3 is each independently selected from the group consisting of H and monovalent hydrocarbon radicals having 1 to 8 carbon atoms, preferably each independently selected from the group consisting of H, methyl, ethyl and phenyl, in particular each independently selected from the group consisting of H and methyl;

[0036] R 4is in each case independently selected from the group consisting of H, monovalent hydrocarbon radicals having 1 to 8 carbon atoms and acyl radicals having 1 to 8 carbon atoms, preferably in each case independently selected from the group consisting of H, methyl and acetyl, in particular H; a = 0 to 2, preferably 0 to 1, in particular 0; b = 1 to 3, preferably 1 to 2, in particular 1; c = 2 to 100, preferably 3 to 50, in particular 4 to 30; d = 1 to 3, preferably 1 to 2, in particular 1; with the proviso that: a+b = 1 to 3, preferably 1 to 2, in particular 1.

[0037] Formula (I) encompasses any permutation of the units, the number of which is indicated by the indices a and b, respectively. The units can be randomly distributed, arranged in a gradient, or arranged in a block pattern. However, the units are preferably randomly distributed, since the polyethersiloxanes are preferably prepared from equilibrated SiH-functional siloxanes.

[0038] Formula (II) encompasses every permutation of the units, the number of which is indicated by the index c. Thus, the units of formula (II) can be randomly distributed, arranged in a gradient, or arranged in a block-like manner.

[0039] The indices a, b, c, and d can be natural numbers or arithmetic means. The indices are preferably natural numbers.

[0040] Preferably, the following also applies to the at least one polyethersiloxane: R = methyl, Z = -CH2CH2CH2-, R 4 = H and d = 1.

[0041] Preferably, the divalent polyether radicals (OC2H3R 3 )c are each independently selected from radicals of the formula (III),

[0042] (OC2H4)c(i)(OC3H6)c(2)(OC4H8)c(3)(OC2H3Ph)c(4) Formula (III); wherein:

[0043] Ph is phenyl; with: c(1) = 1 to 100, preferably 2 to 50, in particular 4 to 30; c(2) = 0 to 70, preferably 1 to 40, in particular 2 to 20; c(3) = 0 to 5, preferably 0 to 2, in particular 0; c(4) = 0 to 5; preferably 0 to 2, in particular 0; with the proviso that: c(1)+c(2)+c(3)+c(4) = c. Formula (III) includes every permutation of the units in the remainder of formula (III), the number of which is indicated by the indices c(1), c(2), c(3) or (c4). The units of formula (III) can therefore be randomly distributed, arranged in a gradient or in a block manner.

[0044] The indices c(1), c(2), c(3), and c(4) can be natural numbers or arithmetic means. The indices are preferably natural numbers.

[0045] Preferably, in formula (II I), the units marked with the index c(1) represent those which have originated from ethylene oxide, the units marked with the index c(2) represent those which have originated from propylene oxide, the units marked with the index c(3) represent those which have originated from butylene oxide and the units marked with the index c(4) represent those which have originated from styrene oxide.

[0046] It is therefore preferred that the monovalent polyether radical R 2 of formula (II) comprises one or more divalent polyether radicals of formula (III) based on ethylene oxide, propylene oxide, butylene oxide and / or styrene oxide or mixtures thereof.

[0047] It is particularly preferred that the monovalent polyether radical R 2of formula (II) comprises exactly one divalent polyether radical of formula (III), wherein said polyether radical is based on ethylene oxide, propylene oxide, butylene oxide and / or styrene oxide or mixtures thereof.

[0048] It is particularly preferred that the monovalent polyether radical R 2 of formula (II) comprises one or more divalent polyether radicals of formula (III) based on ethylene oxide and / or propylene oxide, but not on butylene oxide and styrene oxide. It is therefore particularly preferred that c(3) = c(4) = 0. This further improves the solubility of the polyethersiloxane in water.

[0049] It is also particularly preferred here that the monovalent polyether radical R 2 of formula (II) comprises exactly one divalent polyether radical of formula (III), wherein this polyether radical is based on ethylene oxide and / or propylene oxide, but not on butylene oxide and styrene oxide. Thus, here too, the following preferably applies: c(3) = c(4) = 0.

[0050] It is preferred that R 2 each independently selected from radicals of the formula -CH2CH2CH2O[C2H5O]c(i)[CH2CH(CH3)O]c(2)R 4 , where R 4 each independently selected from the group consisting of H, methyl and acetyl, but in particular R 4 = H. The corresponding polyethersiloxane is obtainable, for example, by hydrosilylation of a terminally unsaturated polyether of the formula CH=CHCH2O[C2H5O]c(i)[CH2CH(CH3)O]c(2)R 4 with a SiH-functional siloxane, where of course R 4 as for the above-mentioned radicals of the formula -CH2CH2CH2O[C2H5O]c(i)[CH2CH(CH3)O]c(2)R 4 Preferably, R 2 i.e. from a terminally unsaturated polyether of the formula CH=CHCH2O[C2H5O]c(i)[CH2CH(CH3)O]c(2)R 4, the polyether in turn being obtainable from the reaction of ethylene oxide and optionally propylene oxide with allyl alcohol. It is further preferred that the number of oxyethylene groups (OC2H4) is equal to the number of groups (OC2H3R 3 ) with R 3 H in the polyethersiloxane in a ratio of 0.5 to 20, preferably 0.6 to 10, in particular 0.8 to 6. Preferably, therefore, c(1) / (c(2)+c(3)+c(4)) = 0.5 to 20, preferably 0.6 to 10, in particular 0.8 to 6. This has the advantage that the solubility of the polyethersiloxane in water is further improved. Accordingly, it is also preferred that the

[0051] Mass fraction of oxyethylene groups (OC2H4) relative to the total mass of all groups (OC2H3R 3 ) in the polyethersiloxane is from 20% to 100%, preferably from 30% to 90%, in particular from 40% to 80%.

[0052] It is preferred that the number average molecular weight MN of R 2from 200 g / mol to 2500 g / mol, preferably from 400 g / mol to 2000 g / mol, in particular from 500 g / ml to 1500 g / mol. The number-average molecular weight MN of R 2 is defined as the number-average molecular weight MN of the corresponding unsaturated polyether used in the production of the polyethersiloxane and is determined by gel permeation chromatography (GPC) according to the standard DIN 55672:2016, preferably according to the standard DIN 55672-1:2016.

[0053] It is further preferred that the divalent polyether radical (OC2H3R 3 )c or the polyether residue R 2 calculated without the remainder Z and without the remainder OR 4 a molar mass M(PE) of 140 g / mol to 2460 g / mol, preferably 360 g / mol to 1940 g / mol, in particular 440 g / mol to 1460 g / mol. The molar mass M(PE) is calculated using the equation:

[0054] M(PE) = 44 g / mol * c(1) + 58 g / mol * c(2) + 72 g / mol * c(3) + 120 g / mol * c(4), where c(1), c(2), c(3) and c(4) refer to the indices in formula (III).

[0055] Z is each independently selected from the group consisting of (d+1)-bonded hydrocarbon radicals having 2 to 10, preferably 3 to 4, in particular 3, carbon atoms, optionally interrupted by oxygen atoms. It is further preferred that Z is a divalent or trivalent radical. Preferably, Z is selected from the group consisting of: further preferably selected from the group consisting of: and -CH2CH2CH2-; in particular -CH2CH2CH2-; where the radicals Z in the representation chosen above are bonded on the left to a silicon atom of the siloxane skeleton and on the right to one or two radicals of the formula (OC2H3R 3 )cOR 4 according to formula (I).

[0056] Particularly preferred is the use of at least one polyethersiloxane of the formula (IV), Me3SiO[SiMe2O]a[SiMeR 2 O] b SiMe3 formula (IV), with

[0057] R 2 = each independently selected from monovalent radicals of the formula -CH2CH2CH2O[C2H5O] C( I ) [CH2CH(CH3)O] C (2 ) R 4 ;

[0058] R 4 = each independently selected from the group consisting of H, methyl and acetyl, in particular R 4 = H; a = 0 to 2, preferably 0 to 1, in particular 0; b = 1 to 3, preferably 1 to 2, in particular 1; c(1) = 1 to 100, preferably 2 to 50, in particular 4 to 30; c(2) = 0 to 70, preferably 1 to 40, in particular 2 to 20; with the proviso that conditions (i) and (ii) are met:

[0059] (i) a+b = 1 to 3, preferably 1 to 2, in particular 1;

[0060] (ii) c = c(1)+c(2) = 2 to 100, preferably 3 to 50, in particular 4 to 30; as a release agent or release agent component in melt granulation, wherein the indices a, b, c(1), c(2) are as defined in formula (I), (II) or (III).

[0061] Very particular preference is given to the use of at least one polyethersiloxane of the formula (V), Me3SiO[SiMeR 2 O]SiMe3Formula (V), with

[0062] R 2 = each independently selected from monovalent radicals of the formula -CH2CH2CH2O[C2H5O] C( I ) [CH2CH(CH3)O] C (2 ) R 4 ;

[0063] R 4 = each independently selected from the group consisting of H, methyl and acetyl, in particular R 4= H; c(1) = 1 to 100, preferably 2 to 50, in particular 4 to 30; c(2) = 0 to 70, preferably 1 to 40, in particular 2 to 20; with the proviso that: c = c(1)+c(2) = 2 to 100, preferably 3 to 50, in particular 4 to 30; as a release agent or release agent component in melt granulation, where the indices a, b, c(1), c(2) are as defined in formula (I), (II) or (III). The polyethersiloxanes to be used according to the invention preferably have a cloud point (cloud point) of greater than 30°C. The cloud point can be determined as for mineral oil products according to the standard DIN EN 23015:1994-05 or the standard DIN EN ISO 3015:2018-04.

[0064] Preferably, the polyether siloxanes used are largely or completely biodegradable. Biodegradability is preferably determined according to the OECD 301 F method. More preferably, biodegradability is determined according to OECD 301 F after 28 days at 22°C. Further preferably, biodegradability is determined as described in EP 3106033 A1, in particular as described in the examples therein. It is preferred that the polyether siloxanes have a biodegradability of greater than or equal to 60%, in particular greater than or equal to 65%, with the maximum value being 100%.

[0065] The polyethersiloxanes can be obtained, for example, in a manner known to those skilled in the art by hydrosilylation from the corresponding unsaturated polyethers and the corresponding SiH-functional siloxanes. The preferred process for preparing the polyethersiloxanes is a transition metal-catalyzed hydrosilylation of the unsaturated polyethers with SiH-functional siloxanes to form Si-C bonds, as described, for example, in EP 1520870, EP 1439200, EP 1544235, US 4147847, US 4025456, EP 0493836, or US 4855379 and the documents cited therein. A platinum catalyst is preferably used to catalyze the hydrosilylation.

[0066] The preparation of the unsaturated polyethers used in the hydrosilylation, on which the radicals of formula (II) or (III) are based, preferably allyl polyethers, is also known from the prior art. For example, EP 1360223 and the documents cited therein describe the preparation of unsaturated polyethers with and without derivatization of the OH functionality. US 5877268 and US 5856369 describe the preparation of allyl-initiated polyethers using DMC catalysis. DE 19940797 describes the preparation and use of polyalkylene oxides using potassium methoxide as a catalyst. Further processes are described in US 3957843, US 4059605, US 3507923, DE 102005001076, and DE 3121929.

[0067] The polyethers are preferably prepared by reacting a starting alcohol, preferably allyl alcohol, with ethylene oxide and / or propylene oxide. The polymerization of the alkylene oxides can be carried out neat or in any desired mixture. The sequence of the addition steps can be arbitrarily selected, so that, depending on the procedure, randomly, block-wise, or gradient-wise unsaturated polyethers are obtained.

[0068] Particularly suitable polyethersiloxanes are described in EP 3106033 A1 and WO 2016 / 202564 A1. Specific reference is made to the aforementioned documents regarding the polyethersiloxanes used.

[0069] The polyether siloxanes according to the invention can themselves be used as release agents or as a release agent component of a release agent. If the polyether siloxanes are used as a release agent component, the release agent used is preferably a mixture or solution of the polyether siloxanes in a solvent. The solvent can be water or an organic solvent. Alcohols, in particular ethanol, are preferred as organic solvents. The polyether siloxanes are particularly preferably used in the form of aqueous solutions. It is therefore preferred that a composition containing or consisting of the at least one polyether siloxane and water is used as the release agent. It is preferred that the mass fraction of the at least one polyether siloxane in the release agent is from 0.5% to 50%, preferably 5% to 30%, in particular 10% to 20%.The aqueous solutions particularly used as release agents therefore preferably contain from 0.5 to 50% by weight, more preferably from 1 to 25% by weight, and most preferably from 3 to 18% by weight of polyether siloxanes.

[0070] It is particularly advantageous if the polyether siloxanes used are "superspreaders." A superspreader drastically reduces the surface tension of the water. The superspreader thus enables extremely good wetting of surfaces with the aqueous solution containing it. It is therefore preferred that a mixture of 0.1 part by weight of the at least one polyether siloxane and 99.9 parts by weight of water has a spreading area of ​​10 to 60 cm 2 , preferably from 15 to 50 cm 2 , especially from 20 to 40 cm 2on a polypropylene film. Specifically, the spreading is determined by applying a 50 μl drop of the test solution to a standard polypropylene film (e.g., type: Forco-OPPB, Van Leer). The drop is applied with a micropipette. The spread area is measured 90 seconds after application. The tests are conducted at 23°C and a relative humidity of 60%.

[0071] The polyethersiloxanes used preferably have a cloud point of 30°C to 70°C, especially 35°C to 60°C. The cloud point is preferably determined in accordance with DIN EN 1890. Of the methods specified therein, the one in which 1 g of sample is measured with 100 g of water is preferred. A correspondingly prepared solution is heated in a test tube / beaker until a noticeable cloudiness occurs. Upon cooling in air while stirring with a thermometer, the temperature at which the solution is clear or only slightly opalescent is determined.

[0072] The substances to be granulated can, for example, be selected from the group consisting of alkanesulfonate, aluminum sulfate, ammonium nitrate, ammonium phosphate, anthracene, antioxidants, antiozonant, asphalt, benzoic acid, bis-hydroxyethyl terephthalate (BHET), bisphenol A, bitumen, caprolactam, carbazole, crotonic acid, diaminodiphenylmethane (DMA), emulsifiers, fat chemicals, photographic gelatin, urea, resins (such as acrylic resin, rosin, epoxy resin, hydrocarbon resin, phenolic resin, polyamide resin, polyester resin, silicone resin, tall oil resin), calcium stearate, cobalt naphthenate, cobalt stearate, lactam 12, fats, cocoa mass, cheese, chocolate, gelatin, chewing gum base, sauces, soup concentrates, masterbatches, naphthalene, sodium acetate, neopentyl glycol (NPG), paradichlorobenzene, pitch, Pesticides, polyethylene glycol, polyethylene terephthalate (PET), polystyrene, polyvinyl acetate, powder coatings, PVC additives, PVC stabilizers, cleaning agents, soaps, synthetic hot melt adhesives (e.g.based on ethylene vinyl acetate), polyurethane, polyamide or polyester, reactive hot melt adhesives, sulfur, sulfur + bentonite, sorbitol, stabilizers, stearic acid, surfactants, toluene diisocyanate (TDI), triazole (BTA, TT A), trimellitic anhydride (TMA), triphenyl phosphate (TPP), supercooling or supercooled melts, UV stabilizers, waxes (such as paraffin, AKD wax, micro wax, PE wax, PP wax, beeswax, filled wax, scented wax, wax colors, montan wax or coating wax, detergent additives), zinc nitrate or zinc stearate. Sulfur is very particularly preferably the substance to be granulated. It is therefore particularly preferred that sulfur is granulated during melt granulation.

[0073] It is preferred that 0.01 to 0.04 g, preferably 0.01 to 0.03 g, in particular 0.01 to 0.02 g of the at least one polyether siloxane are used per kg of the substance to be granulated or per kg of melt.

[0074] Melt granulation is preferably carried out as described in US 6398989 and US 4279579. Reference is expressly made to the aforementioned documents regarding the equipment used and the basic procedure.

[0075] A further subject matter is a process for producing melt granules, characterized in that the at least one polyether siloxane is used as a release agent or release agent component according to the invention.

[0076] It is preferred that the release agent is applied to a surface of a metal support, a melt is applied to the surface treated with the release agent, the melt is cooled until solidification is achieved, and the resulting melt granulate is separated from the metal support. The release agent according to the invention is therefore preferably applied before the melt is applied to the metal support. The release agent can be applied, for example, by spraying the release agent onto the metal support. The amount of release agent can be freely selected within wide ranges. It is further preferred that the melt is applied to the metal support in the form of drops. The metal support is preferably a steel belt. Accordingly, it is also preferred to use a steel belt cooler.When using a steel belt cooler, the melt of the material to be granulated is applied to the steel belt treated with the release agent, whereby the melt on the steel belt is cooled below the melting temperature or the solidification temperature by preferably cooling the steel belt from below by means of a coolant, preferably water, and thus solidifies.

[0077] If the melting point of the material to be granulated exceeds 100 °C (e.g., sulfur), the polyether siloxanes separate during melt granulation due to the evaporation of the water. In the immediate vicinity of the hot melt, the polyether siloxanes precipitate from the aqueous solution due to their preferred cloud point in the range of 30 to 70 °C and adsorb in extremely thin layers on the surface of the sulfur and the surface of the steel belt. They thus ensure the separation of the granules and influence the shape of the melt granules so that they preferably have a spherical shape and thus have minimal contact with the surface of the steel belt.

[0078] A further subject matter therefore also includes melt granules which are obtainable by the use according to the invention of the at least one polyether siloxane and / or the process according to the invention.

[0079] It is preferred that the mass fraction of the at least one polyether siloxane based on the total mass of the melt granules is 1 ppm to 40 ppm, preferably 5 ppm to 30 ppm, in particular 10 ppm to 20 ppm.

[0080] In the examples listed below, the present invention is described by way of example, without the invention, the scope of which emerges from the entire description and the claims, being intended to be limited to the embodiments mentioned in the examples.

[0081] Examples:

[0082] Preparation of the polyethersiloxane according to the invention:

[0083] A 1000 ml three-necked flask equipped with a stirrer and reflux condenser was charged with 0.5 mol of a polyether of the formula CH2=CHCH2(OC2H4)8(OC3H6)3.3OH and heated to 90°C. Subsequently, 10 ppm of Pt in the form of a toluene solution of the Karstedt catalyst (2 mol% Pt content) was added. The mixture was stirred for 10 min, and then 0.38 mol of SiH groups in the form of the SiH-functional siloxane Me3SiO[SiMeHO]iSiMe3 were added dropwise over a period of 15 min. An exothermic reaction was observed, and the reaction mixture was stirred for a further 4 h at 90°C. In all cases, no further SiH functions could be detected by gas volumetric analysis.

[0084] Application-related testing:

[0085] The effectiveness of the present invention was tested in a practical test and compared with conventionally used organomodified siloxanes and silicone oil emulsions. A laboratory system from IPCO was used, which contains a Rotoformer® and a water-cooled steel belt (Rotoform System). The test conditions listed below were maintained. A 14 wt. % aqueous solution or mixture was produced from the release agent component used as a release agent, which was continuously sprayed onto the steel belt. The starting materials and a description of the release performance can be found in Table 1.

[0086] Test conditions:

[0087] Belt speed: 11.25 m / min

[0088] Rotoformer speed: 12 m / min

[0089] Sulfur temperature: 145°C

[0090] Cooling water temperature: 22°C

[0091] Steel belt width: 150 mm

[0092] Cooling length of the conveyor belt: 2.4 m Release agent: Consumption approx. 0.02 g active substance (used as a 14 wt.% aqueous solution or mixture) per kg sulfur

[0093] Table 1: Release agent component and test results

[0094] As can be seen from Table 1, the polyethersiloxane according to the invention exhibits better properties than the release agents or release agent components previously known from the prior art. The melt granules according to the invention exhibit the best shape (an absolutely uniform spherical shape). This is also reflected in the slightly higher internal temperature of the melt granules according to the invention after their production compared to the non-inventive melt granules, since the contact area with the cooling belt is minimal due to the almost perfect shape of the melt granules according to the invention.

Claims

Patent claims:

1. Use of at least one polyether siloxane having less than 20, preferably 3 to 5, in particular 3 to 4 silicon atoms as a release agent or release agent component in melt granulation. Use according to claim 1, characterized in that the at least one polyethersiloxane is selected from compounds of formula (I), Formula (I); where: R is each independently selected from the group consisting of monovalent hydrocarbon radicals having 1 to 10 carbon atoms, preferably each independently selected from the group consisting of methyl, ethyl, propyl and phenyl, in particular methyl; R 1 is each independently selected from the group consisting of R and R 2 , preferably R, especially methyl; R 2is each independently selected from the group consisting of monovalent polyether radicals of the formula (II), -Z[(OC2H3R 3 )cOR 4 ]d formula (II); Z is each independently selected from the group consisting of (d+1)-bonded hydrocarbon radicals having 2 to 10, preferably 3 to 4, in particular 3, carbon atoms, optionally interrupted by oxygen atoms; R 3 is each independently selected from the group consisting of H and monovalent hydrocarbon radicals having 1 to 8 carbon atoms, preferably each independently selected from the group consisting of H, methyl, ethyl and phenyl, in particular each independently selected from the group consisting of H and methyl; R 4is each independently selected from the group consisting of H, monovalent hydrocarbon radicals having 1 to 8 carbon atoms and acyl radicals having 1 to 8 carbon atoms, preferably each independently selected from the group consisting of H, methyl and acetyl, in particular H; a = 0 to 2, preferably 0 to 1, in particular 0; b = 1 to 3, preferably 1 to 2, in particular 1; c = 2 to 100, preferably 3 to 50, in particular 4 to 30; d = 1 to 3, preferably 1 to 2, in particular 1; with the proviso that: a+b = 1 to 3, preferably 1 to 2, in particular 1.

3. Use according to claim 2, characterized in that: R = methyl, Z = -CH2CH2CH2-, R 4 = H, d = 1.

4. Use according to one of claims 2 to 3, characterized in that the divalent polyether radicals (OC2H3R 3)c are each independently selected from radicals of the formula (III), (OC2H4)c(i)(OC3H6)c(2)(OC4H8)c(3)(OC2H3Ph)c(4) Formula (III); wherein: Ph is phenyl; with: c(1) = 1 to 100, preferably 2 to 50, in particular 4 to 30; c(2) = 0 to 70, preferably 1 to 40, in particular 2 to 20; c(3) = 0 to 5, preferably 0 to 2, in particular 0; c(4) = 0 to 5; preferably 0 to 2, in particular 0; with the proviso that: c(1)+c(2)+c(3)+c(4) = c.

5. Use according to claim 4, characterized in that: c(3) = c(4) = 0.

6. Use according to one of claims 1 to 5, characterized in that a composition containing or consisting of the at least one polyether siloxane and water is used as the release agent.

7. Use according to one of claims 1 to 6, characterized in that the mass fraction of the at least one polyether siloxane in the release agent is from 0.5% to 50%, preferably 5% to 30%, in particular 10% to 20%.

8. Use according to one of claims 1 to 7, characterized in that sulfur is granulated during the melt granulation.

9. Use according to one of claims 1 to 8, characterized in that 0.01 to 0.04 g, preferably 0.01 to 0.03 g, in particular 0.01 to 0.02 g of the at least one polyether siloxane are used per kg of melt.

10. A process for producing melt granules, characterized in that the at least one polyether siloxane is used as a release agent or release agent component according to the specifications of at least one of claims 1 to 9.

11. A method according to claim 10, characterized in that the release agent is applied to a surface of a metal carrier, a melt is applied to the surface treated with the release agent, the melt is cooled until solidification and the melt granulate thus obtained is separated from the metal carrier.

12. Method according to claim 11, characterized in that a steel strip is used as the metal carrier.

13. Method according to one of claims 10 to 12, characterized in that a steel belt cooler is used.

14. Melt granules obtainable by the use according to any one of claims 1 to 9 and / or obtainable by the process according to any one of claims 10 to 13.

15. Melt granules according to claim 14, characterized in that the mass fraction of the at least one polyether siloxane based on the total mass of the melt granules is 1 ppm to 40 ppm, preferably 5 ppm to 30 ppm, in particular 10 ppm to 20 ppm.

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