Processing aid for producing a surface coating having Anti-stick properties, formulation for producing the processing aid and surface coating having Anti-stick properties

Abstract

To provide a formulation for producing a processing aid.SOLUTION: A formulation for producing a processing aid comprises an active substance having a surface-affinitive component and an inorganic component, wherein the inorganic component comprises at least one inorganic mineral, wherein the surface-affinitive component comprises at least one alkaline-earth metal stearate and a complexing agent for forming an alkaline-earth metal complex, wherein the proportion of the inorganic component in the active substance of the formulation is 3 to 92% by weight, the proportion of the alkaline-earth metal stearate in the active substance of the formulation is 5 to 50% by weight and the proportion of the complexing agent in the active substance of the formulation is 0.1 to 3% by weight. The invention further relates to a processing aid obtainable from the preparation by dispersion in water and to a release agent. The release agent is obtained by applying a processing aid to the substrate and / or mould surface, preferably forming a coating on the surface of the substrate and / or mould.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] In general, the present invention relates to formulations for producing processing aids, such as release agents or stripping agents, especially for processing and manufacturing polymers, elastomers, rubbers, and / or rubber compounds. In particular, the present invention relates to release agents for application to polymer-based precursors and / or molds to be treated in processing and manufacturing processes, or release agents for polymer articles and / or molds. [Background technology]

[0002] Processing aids for producing at least temporary coatings on the surface of polymer-based workpieces are used as release or mold release agents in the production and processing of articles consisting of or containing polymers, such as rubber compounds. A processing aid is understood to be an agent that is applied to the surface of an article and / or molding element consisting of or containing a polymer, especially an elastomer or rubber compound. Surface-applied processing aids that preferably form a film on the article surface and / or mold surface are referred to as release agents. The purpose of release or mold release agents is to prevent the adhesion of the manufactured article to molding elements, to other similar elastomeric articles, and / or to each other.

[0003] The coating containing the release agent or processing aid may also remain on the substrate and be further processed therewith.

[0004] The release agent or the corresponding coating is formed so that two surfaces covered with the release agent film or the coating containing the release agent do not stick to each other. Therefore, between two substrate surfaces covered with the release agent, the release agent or the film formed therefrom or the coating formed therefrom has the function of a release film. At the same time, the release agent contains a component that ensures the coating of the substrate surface.

[0005] When manufacturing products consisting of or containing polymers, including elastomers, in particular natural and / or synthetic rubbers, these are initially present in unvulcanized or prevulcanized form, for example as rubber compounds. Prevulcanized rubbers are understood to be rubbers that are already low in crosslinking and may also be dimensionally stable, but still have a sufficient number of polymerizable or crosslinkable groups to be converted into elastomers through a crosslinking reaction in a subsequent step.

[0006] In many manufacturing processes for producing products consisting of or containing elastomers, the rubber compound used as the starting material is converted into rubber belts or bands, especially rubber sheets, in a first process step. These belts or bands are often laminated or folded before the next processing step, such as final or final shaping and / or vulcanization of the rubber into an elastomer, is carried out. During this storage, processing aids prevent the rubber belts or bands from sticking together, while ensuring that the processing aids do not affect the crosslinking reaction or alter the properties of the raw materials, precursors, or products in any way during or after the process. This ensures a reliable, otherwise neutral behavior during the processing, storage, and manufacturing process.

[0007] In the vulcanization of rubber in a mold, such as in the manufacture of hoses, the release agent also prevents the rubber and / or vulcanized elastomer from adhering to the surfaces of the mold or form.

[0008] The prior art is known to provide processing aids, for example, in the form of release agents or stripping agents, that prevent direct contact between product surfaces and / or with the surface of a molding element, thus preventing adhesion and / or adhesion of the surfaces. Within the context of this disclosure, "direct contact" is understood to mean contact between the surface of the product and another surface, such as the surface of a mold or another part of the product (e.g., another part of a polymer belt). This is the case, for example, when a film consisting of or containing the processing aid is applied to at least one of the surfaces in question in accordance with the present disclosure. However, it is not absolutely necessary for the processing aid to be applied to at least one surface in the form of a coating and / or film; it can also be applied to the surface in the form of, for example, a powder. It may also be possible for the processing aid to be incorporated into the material of one of the surfaces, for example, a polymeric material. The effect of the processing aid, whatever form it is used in, is intended to be the prevention of adhesion or adhesion of the surfaces.

[0009] In this case, the processing aid, which is usually a release agent, can be referred to as a spacer, space former, or space-forming component, and contains at least one component that prevents or at least inhibits physical and / or chemical bonding between the surface of the product and other surfaces. For this purpose, the release agent or release agent particularly contains inorganic particulate components, such as silicates, especially phyllosilicates, chalk, or carbonates. The inorganic particles function as mechanical spacers, i.e., provide spatial separation of surfaces. Therefore, rubber products can be easily peeled from molded parts, and the rubber surfaces of, for example, rubber belts or bands, do not stick to each other. Inorganic particulate components are often also referred to as powders to describe the formulation.

[0010] Within the framework of this disclosure, a powder is understood to be a dosage form consisting essentially of particles, including agglomerates. The inorganic phase, the organic phase or the mixture of organic and inorganic phases, preferably present in granular form, is referred to as the powder component.

[0011] While processing aids are intended to prevent product surfaces from sticking to each other, the processing aid itself must have good adhesion to the product surface and be applied evenly. If the substrate is a rubber compound to which the processing aid is applied, the processing aid must have good adhesion to the rubber surface and be able to be applied as evenly as possible to ensure that rubber sticking is avoided throughout the processing process.

[0012] In particular, poor or insufficient adhesion of the processing aid to the product surface can lead to insufficient adhesion of the processing aid to the product surface. This can lead, for example, to peeling of the processing aid, which can result in correspondingly low storage stability of the processing aid on the product surface. Furthermore, if a processing aid, such as a release agent, is used improperly or has low storage stability, peeling of the processing aid can lead to contamination of manufacturing equipment. Therefore, to ensure good adhesion of the processing aid to the surface of the workpiece, the processing aid typically contains at least one organic component, hereinafter also referred to as a surface-affinity component. At the same time, the processing aid must not become a component of the overall formulation of the workpiece and must not change its composition in such a way that the product properties of the respective substrate are changed.

[0013] Thus, it is contemplated that the processing aid will achieve the release effect without altering the properties or appearance of the workpiece or the product made therefrom. Therefore, excessive application of the release agent to the surface of the workpiece, which would also be classified as improper use, is disadvantageous and should be avoided.

[0014] According to Patent Document 1, in addition to montmorillonite, metal stones are used as high-flow agents or lubricants. 鹸 A mold release agent containing

[0015] Patent Document 2 describes a processing aid for processing unvulcanized rubber workpieces, which contains smectite and / or silicate, carbonate, metal oxide, or inorganic sulfate as an inorganic component. Additionally, the release agent contains a metal salt of a fatty acid. The processing aid forms a film on the rubber surface. In this case, the fatty acid salt increases the flexibility of the film.

[0016] Patent Document 3 discloses a release agent for rubber, which contains smectite as an inorganic component and at least one other inorganic component, such as another inorganic silicate or metal oxide. A metal salt of a long-chain fatty acid is used as the organic, rubber-compatible component. Additionally, the release agent contains a water-soluble, film-forming polymer.

[0017] The processing aid can be applied to the surface of the workpiece, for example, in a so-called wet method. For this purpose, an aqueous dispersion of the release agent is applied to the surface of the workpiece. In this case, the temperature of the workpiece surface, for example, the surface of a rubber sheet, is typically raised to a range of 80 to 150°C. Therefore, the processing aid and the components of the release agent precipitated on the surface should have appropriate temperature stability.

[0018] Application can be carried out by either a spraying method or a dipping method, in which the product is immersed in the dispersion. In the dipping method, a volumetrically heated workpiece, such as a volumetrically heated rubber, is continuously immersed in the processing aid. This can result in permanent temperature stress of the processing aid or its components. In addition, application of the dispersed solids to the surface of the workpiece continuously reduces the solids content in the processing aid. This can involve changes in the pH value of the processing aid and, therefore, changes in the deposition conditions during the application process to the workpiece surface. [Prior art documents] [Patent documents]

[0019] [Patent Document 1] Patent No. 5998079 [Patent Document 2] JP 2018-193416 A [Patent Document 3] US Patent Application Publication No. 2020 / 0255604 Summary of the Invention [Problem to be solved by the invention]

[0020] The problem underlying the present invention is therefore to provide a formulation for producing a processing aid and a processing aid which makes it possible to provide a surface coating with an anti-sticking effect and good storage stability, without the product properties of the workpiece being affected or changed. [Means for solving the problem]

[0021] The object of the present invention is already achieved by the subject matter of the independent claims. Advantageous configurations and developments are the subject matter of the subclaims.

[0022] The present invention relates to a formulation for producing a processing aid, in particular a release agent or release agent for workpieces, preferably consisting of or comprising an organic polymer. The polymer may be, for example, a rubber, an elastomer, a thermoplastic or a thermoplastic elastomer.

[0023] A formulation (also "preparation") is understood in the context of the present disclosure to be a mixture of substances that can be converted into a processing aid by the addition of at least one further component, preferably a liquid component, in particular an aqueous component. It is therefore a kind of "intermediate product" or "semi-finished product" in the production of processing aids.

[0024] Thus, a formulation is understood in the sense of the present disclosure to be a precursor of a processing aid that is converted, preferably by adding water, into a dosage form suitable for use and thus into a processing aid. The formulation may be in the form of a powder, granules, or still have a flowable, pumpable gel or paste-like consistency.

[0025] The processing aid, or the processing aid applied to the surface of the substrate and / or mold, may have the effect of a release agent, lubricant, anti-blocking agent, anti-sticking agent, release agent, or product release agent. The term processing aid, in the sense of the present disclosure, describes a ready-to-use formulation for application to a surface, in particular to a substrate surface or a mold surface. The processing aid applied to the surface, or the components of the processing aid remaining on the surface, are also referred to as a release agent or release agent film, in the sense of the present disclosure.

[0026] Storage stability is understood within the context of this disclosure to be the property of a formulation-based processing aid or release agent that combines with a surface, particularly a polymeric or elastomeric surface, such that the processing aid's function of achieving release action between two surfaces, particularly as a film or coating, can be maintained over the period of storage of the substrate.

[0027] Processing aids are generally used in the production and / or further processing of organic polymers, such as rubber compounds, elastomers, or other polymers. Insofar as polymers are mentioned within the scope of this disclosure, this is understood to be in particular organic polymers.

[0028] The processing aid can be prepared from the formulation by dispersing the formulation in a dispersion medium, preferably water. In this case, the formulation can exist as a solid, e.g., a powder, or can contain liquid components. In the case of a formulation present in powder form, this can have a total residual moisture content of 5-10% by weight, due to the residual moisture content of the individual components. In contrast, if the formulation contains liquid components, the moisture content can be 40-85% by weight.

[0029] One embodiment contemplates that the formulation consists of 100% of the active ingredient, hereinafter also referred to as the active substance. In this embodiment, the formulation is preferably present as a powder or paste.

[0030] Alternatively, the formulation may be a dispersion, particularly an aqueous dispersion, whose water content may be 40-85 wt. % as described above, and which is then further increased to produce the processing aid. Thus, in embodiments with a correspondingly high water content, the formulation may also be in the form of a dispersion that is further diluted to produce the processing aid. Thus, in these embodiments, the formulation is present as a concentrated dispersion.

[0031] In this embodiment, the proportion of active substance in the formulation is therefore in the range of 15-60% by weight.

[0032] Within the scope of this disclosure, it is generally understood that processing aids and formulations differ essentially in the concentration of the active substance. In particular, formulations can be in powder form or as concentrated dispersions, while processing aids can be in the form of dispersions or suspensions. Insofar as formulations are considered within the scope of this disclosure, statements explicitly referring to processing aids rather than formulations also apply correspondingly to processing aids, and vice versa, unless the context clearly dictates otherwise, as is the case, for example, in the application and effects of release agent films. Insofar as ingredients and their contents are considered, it is understood that these relate to the active substance content of the processing aid (i.e., without the inclusion of additional liquid, especially aqueous, phases). The same applies to the formulation itself, which in the ideal case consists purely of active substance and, if necessary, contains only small amounts of adsorptively bound liquid, such as absorbed water, for example, in the form of residual moisture content. In the case of aqueous formulations, the content refers to the content of active substance in the formulation, i.e., does not take into account the moisture content in particular.

[0033] The formulations therefore contain higher concentrations of active ingredients than processing aids. Active ingredients or active substances are understood in the sense of the present disclosure to be ingredients that lead to the formation of a surface coating with anti-stick effect and that in combination ensure the inherent release effect properties of the substrate.

[0034] The processing aids are used in particular in the form of a dispersion or suspension, for example a coarse dispersion or a fine suspension, and can be applied, for example, to a mold or to the surface of the manufactured product. In particular, the processing aid or release agent can form a release film on the surface of the product and / or tool.

[0035] Processing aids are initially applied to a surface as a release agent in the form of a film (or coating), but may remain thereon and be present during further processing steps, and thus remain in or be incorporated into the product. Furthermore, after being applied to the surface of a substrate or any type of raw material surface, the release agent may be completely or partially removed from the respective surface through downstream processing steps when the release or anti-stick function is no longer required. This may be done by washing.

[0036] The components of the processing aid precipitated on the surface of the workpiece and / or mold form a surface coating with an anti-sticking effect, also referred to as a release agent within the framework of this disclosure. A release agent, particularly in the form of a release agent film, can be obtained by applying solid components of the processing aid, particularly after they have at least partially dried. In particular, the release agent is a solid compound containing an organic component and an inorganic component. Preferably, the solid compound forms a release agent film on the surface of the workpiece.

[0037] The formulation contains at least one inorganic component and one organic component. In this case, the organic component includes a component that forms a film on the surface of the workpiece and / or mold, and the component has inorganic material particles embedded therein. In particular, the organic component includes a component that at least partially melts to form a release agent film or coating on the heated surface of the workpiece when the processing aid is applied to the surface. The organic component includes a surface-affinity component or a component that has surface affinity for the surface of the workpiece. Furthermore, the release agent film forms a spacer between two substrates. In particular, when the release agent film melts and bonds to the substrate or mold surface, it may have a surface structure with locally different thicknesses, so that, for example, two overlapping substrate surfaces coated with the release agent film come into full contact due to local protrusions in the release agent film.

[0038] The inorganic component present in the formulation in granular form comprises at least one inorganic mineral. The inorganic component may also comprise a mixture of different inorganic minerals. In the release agent, the inorganic mineral ensures direct contact between the workpiece surface and the mold or between various workpieces or workpiece parts. Preferably, the particle size distribution D of the granular inorganic mineral is 50 The particle size is in the range of 0.3 to 15 μm, preferably in the range of 0.5 to 12 μm, and particularly preferably in the range of 0.7 to 10 μm. The particle size distribution can be determined by laser diffraction particle size analysis or laser granulometry, which is essentially based on Fraunhofer diffraction. The corresponding granular material is dispersed in a commercially available detergent for this purpose. This particle size distribution ensures that the inorganic mineral particles are large enough not to completely settle within the organic component or organic film and thus to be able to function as spacers. At the same time, the particle size is limited to ensure a sufficiently stable embedding of the particles in the organic film, thereby ensuring good storage stability of the release agent film.

[0039] Alternatively or additionally, in one embodiment of the present invention, the oil absorption of at least one granular mineral of the inorganic component is in the range of 20 to 90 ml / 100 g, preferably in the range of 35 to 65 ml / 100 g. Oil absorption is a measure of the absorption capacity of mineral particles, where particles with a higher oil absorption have a higher absorption capacity than particles with a lower oil absorption.

[0040] The use of swellable inorganic materials, especially phyllosilicates, has proven particularly advantageous. For these, particle size distribution cannot be determined for characterization by swelling capacity, because swelling that occurs upon contact with liquid impairs the quality of the measurement. Instead, the swelling capacity of this type of inorganic material is determined as follows: This so-called swelling test is carried out in accordance with the ASTM D5890 standard (Standard Test Method for Swell Index of Clay Mineral Component of Geosynthetic Clay Liners). To do this, a measuring cylinder is first filled with 100 ml of water, and then a total of 2 g of silicate is sprinkled on the water surface in approximately 0.1 g increments. A waiting time of at least 10 minutes is maintained between additions to allow time for each portion to hydrate and sink to the bottom of the cylinder. After addition of the total amount, the measuring cylinder is covered and protected from external disturbances for a period of 24 hours. As a result, after 24 hours, the volume of the swollen phyllosilicate phase can be read to an accuracy of 0.5 ml. The swelling capacity of the phyllosilicates determined by this procedure should be at least 20 ml, preferably at least 30 ml, particularly preferably at least 40 ml in ion-containing water, such as tap water. In water with a low ion content, such as so-called distilled water, the swelling capacity should be at least 15 ml, preferably at least 25 ml, particularly preferably at least 35 ml.

[0041] The results of this swelling test contain the same information content as can be determined by the so-called "swelling power" test, as described in JBAS-104-77. This is a standard test method of the JPMA (Japan Bentonite Industry Association). In this case, 2.0 g of the corresponding clay material powder or clay mineral powder is added in small amounts to 100 ml of water in a measuring cylinder, and the sedimentation behavior is then observed. In this way, the volume of the swelling and swollen clay mineral is determined. Preferably, the formulation contains at least one inorganic swelling mineral, in particular smectite, montmorillonite, stevensite, and / or sepiolite. In this case, the mentioned mineral may also be included as a component of the mineral compound.

[0042] The swelling minerals mentioned above have good swelling properties and act as rheological additives. The use of these minerals ensures that the inorganic components of the dispersion do not settle as sediment. In particular, 1-5% formulations containing inorganic minerals do not show visible phase separation, i.e., no sediment is visible to the naked eye, even after relatively long periods of time.

[0043] Additionally or alternatively, the inorganic component may, according to one embodiment, also comprise as inorganic minerals minerals with less or no swelling capacity, such as, for example, talc or kaolin.

[0044] According to a further embodiment, the inorganic component comprises, as a particulate mineral, an inorganic carbonate instead of or in addition to the aforementioned minerals. Preferably, the inorganic component comprises calcium carbonate as a particulate mineral. According to one embodiment, calcium carbonate is included in the formulation as chalk. Alternatively or additionally, the inorganic component may comprise a mineral with no or only little swelling capacity, in particular kaolin. One embodiment contemplates that the inorganic component comprises at least one swelling mineral and at least one inorganic carbonate, preferably at least one swelling silicate and at least one inorganic carbonate.

[0045] In addition to its function as a spacer, carbonates can also be used as fillers. Like the swellable silicates in the processing aid or release agent, inorganic carbonates prevent direct contact between workpiece surfaces or between the workpiece surface and the surface of the mold or die. Furthermore, the carbonates in the processing aid, i.e., in the aqueous dispersion of the formulation, can adjust and / or stabilize the pH value of the processing aid. In this way, the carbonates can buffer the pH value in the processing aid. This is particularly advantageous when the processing aid is applied to the workpiece surface by immersion. The inventors speculate that buffering the pH value of the processing aid increases the compatibility of the processing aid with the substrate surfaces of different raw materials. This increases the affinity of the processing aid to the substrate surface, which in turn may be beneficial for storage stability, since higher affinity promotes the formation of a release film.

[0046] According to one embodiment, the formulation comprises 3 to 75% by weight of inorganic carbonate. One embodiment contemplates that the formulation comprises 10 to 53% by weight, preferably 10 to 30% by weight, of inorganic carbonate as particulate inorganic mineral. Preferably, the formulation comprises 10 to 53% by weight, more preferably 10 to 30% by weight, of calcium carbonate.

[0047] The inorganic components in particulate form in the sense of the present disclosure contribute to the avoidance of direct contact as described above. Preventing direct contact is, on the other hand, a factor that contributes to storage stability, since direct contact is not achieved at these locations. This provides a release effect, at least in a locally limited manner.

[0048] In addition, the materials contained in the formulation are outstanding in terms of high-temperature stability. For example, the materials contained in the formulation are chemically stable up to temperatures of at least 160°C. Furthermore, the materials are not volatile at these temperatures, so that the composition of the release agent or release agent film remains constant even at high temperatures. This allows for particularly high maximum thermal stability of the processing aid and the release agent film. Therefore, the inorganic component is also referred to as a matrix stabilizer within the scope of the present disclosure. High thermal stability allows for application of the processing aid to surfaces, particularly rubber surfaces, over a wide temperature range. In particular, the processing aid is suitable for application to surfaces at temperatures up to 160°C or 200°C. According to one embodiment, the decomposition temperatures of the individual components of the formulation are at least 160°C or at least 200°C. The high-temperature stability of the individual components of the formulation results in the release agent also having correspondingly high high-temperature stability. This ensures that the release agent remains on the surface of the workpiece even when applied to a hot surface and does not change its properties or composition. The proportion of inorganic components in the formulation is 3 to 92% by weight, preferably 10 to 85% by weight, particularly preferably 35 to 80% by weight, and very particularly preferably 25 to 55% by weight. One embodiment provides for the proportion of swellable silicates in the formulation to be 5 to 75% by weight, preferably 10 to 65% by weight, and particularly preferably 25 to 55% by weight.

[0049] In addition to the inorganic component, the formulation contains an organic component. The organic component is composed of multiple components and includes an organic compound that has a high affinity for the surface of the workpiece. Within the framework of this disclosure, the organic component is also referred to as a surface-affinity component or a rubber-affinity component. The surface-affinity component creates the surface affinity of the release agent film to the workpiece surface. The surface-affinity component of the formulation enables uniform application of the processing aid to the workpiece surface, thus forming a uniform release agent film. In addition, the surface-affinity component provides adhesion of inorganic minerals to the mostly organic workpiece surface, for example, to rubber surfaces. In this case, the composition of the processing aid can be adapted to the respective workpiece surface. Therefore, the release agent film obtained from the processing aid exhibits high storage stability. A release agent with high storage stability adheres to the surface for a relatively long period of time and / or even under mechanical load, for example, due to friction, while maintaining its release effect.

[0050] Particularly good storage stability in conjunction with a good release effect can be achieved, in particular, when the ratio m(inorganic component) / m(surface affinity component) of the weight ratio of the inorganic component to the surface affinity component is in the range of 0.05 to 18, preferably in the range of 0.5 to 11, particularly preferably in the range of 1 to 9.

[0051] The surface-affinity component of the formulation includes at least one alkaline earth metal stearate and a complexing agent for complexing the alkaline earth metal cation. The alkaline earth metal stearate belongs to the substance group of metal soaps. In the context of this disclosure, metal soap refers to salts of metals and carboxylic acids, and therefore salts of metals and fatty acids, resin acids, and naphthenic acids. Metal soaps are divided into water-soluble and water-insoluble types. Water-soluble metal soaps are often simply referred to as soaps. This applies particularly to water-soluble fatty acid salts of sodium and potassium salts, also known as soaps.

[0052] Fatty acids are generally understood to be mostly unbranched aliphatic monocarboxylic acids. Resin acids are a heterogeneous group of organic acids found, for example, in natural resins. Naphthenic acids are understood here to be carboxylic acids containing at least one cyclopentane and / or cyclohexane group with at least one alkyl substituent. This group of carboxylic acids may also be generally referred to as "soap-forming carboxylic acids" within the context of this disclosure.

[0053] Within the scope of this disclosure, water-soluble metal soaps are understood to be alkali salts of one of the aforementioned carboxylic acids, in particular the sodium and / or potassium salts of one of the aforementioned carboxylic acids, i.e., for example, fatty acids, or mixtures of these substances. Water-soluble soaps can also be called alkaline soaps. In particular, the term water-soluble soaps includes sodium and / or potassium salts of fatty acids, such as sodium and / or potassium stearate and / or sodium and / or potassium oleate, or mixtures thereof.

[0054] Preferably, the metal soap in the sense of the present disclosure comprises an alkaline earth metal, in particular calcium or magnesium, which is not water-soluble, in contrast to the sodium and / or potassium salts of soap-forming carboxylic acids already referred to as "water-soluble".

[0055] Stearates belong to the group of metal soaps and, within the scope of this disclosure, are salts of selected fatty acids. Stearates are understood, within the scope of this disclosure, to be salts of alkanoic acid, margaric acid, palmitic acid, and / or stearic acid in general. Thus, stearates include salts of hexadecanoic acid (n-hexadecanoic acid), heptadecanoic acid (n-heptadecanoic acid), octadecanoic acid (n-octadecanoic acid), and / or mixtures thereof. Preferably, stearates contain salts of octadecanoic acid as the main component, and it is understood that at least 10% by weight, preferably at least 20% by weight, and preferably more than 50% by weight of the stearates are formed as salts of octadecanoic acid. In most cases, the alkanoic acid contained in the stearates is used in combination with various metals such as calcium, zinc, magnesium, sodium, aluminum, and lithium. The following will be mentioned, inter alia, calcium stearate, zinc stearate, magnesium stearate, sodium stearate, aluminum stearate, and lithium stearate. Technical-quality calcium stearate may often contain, in addition to calcium stearate, other calcium salts of higher fatty acids, such as calcium palmitate. This also applies correspondingly to other metal stearates.

[0056] Alkaline earth metal stearates are therefore understood in the sense of the present disclosure to be alkaline earth metal salts of alkanoic acid, hexadecanoic acid and / or heptadecanoic acid and / or octadecanoic acid and / or mixtures thereof. According to one embodiment, the alkaline earth metal stearates may comprise a mixture of at least two of the above-mentioned alkanoic acid salts, preferably with the total proportion of alkanoic acid, hexadecanoic acid and / or heptadecanoic acid and / or octadecanoic acid in the stearate being at least 90% by weight.

[0057] Preferably, the alkaline earth metal stearates comprise as a major component the salt of octadecanoic acid, it being understood that at least 10% by weight, preferably at least 20% by weight, preferably more than 50% by weight of the stearate is formed as the salt of octadecanoic acid. Technical quality calcium stearate may often also contain, in addition to calcium stearate, other calcium salts of higher fatty acids, such as, for example, calcium palmitate.

[0058] According to a preferred embodiment, the alkaline earth metal stearate comprises stearic acid, i.e., an alkaline earth metal salt of n-octadecanoic acid, as the main component. Preferably, the alkaline earth metal stearate comprises at least 40% by weight, preferably at least 60% by weight, of an alkaline earth metal salt of stearic acid. One embodiment contemplates that the alkaline earth metal stearate is an alkaline earth metal salt of stearic acid or one or more alkaline earth metal salts of stearic acid.

[0059] In addition to the release effect described above, alkaline earth metal stearates have a good slip effect and can function as lubricants. By using alkaline earth metal stearates in the formulation or processing aid, a release agent film with particularly high slip effect can be obtained. In addition, alkaline earth metal stearates exhibit good adhesion to rubber due to their hydrophobic organic residue. Furthermore, alkaline earth metal stearates, especially magnesium stearate, can be deposited on the surface of inorganic particles, making the surface of the inorganic particles more hydrophobic and thereby significantly increasing the affinity of the inorganic particles to the surface of the workpiece. Preferably, the formulation contains magnesium and / or calcium stearate, particularly preferably calcium stearate.

[0060] The melting temperatures of magnesium stearate and calcium stearate are in the range of 140-160°C. As a component of the processing aid, the alkaline earth metal stearate lowers the melting point or melting range of the processing aid, resulting in at least partial melting of the processing aid at the rubber surface or molded part surface. This promotes the formation of a release agent film comprising an organic matrix having the alkaline earth metal stearate and inorganic particles dispersed therein.

[0061] By incorporating the inorganic components into an organic matrix, good adhesion of the inorganic components to the workpiece surface and / or molded part surface can be achieved. For this purpose, the formulation contains 5 to 50 wt. %, preferably 9 to 50 wt. %, and particularly preferably 9 to 35 wt. % of an alkaline earth metal stearate. Preferably, the formulation contains magnesium stearate and / or calcium stearate, particularly preferably calcium stearate. For example, one embodiment contemplates that the formulation contains 9 to 35 wt. % calcium stearate.

[0062] As a further component of the surface-affinity component, the processing aid comprises at least one complexing agent for complexing alkaline earth metal cations, in particular for complexing calcium and / or magnesium cations, particularly preferably for complexing calcium ions, which ensures that the processing aid has reproducible properties even when water of different water quality and / or hardness is used to prepare the dispersion.

[0063] Furthermore, it has been surprisingly found that the combination of an alkaline earth metal stearate with a complexing agent can provide a release agent that can ensure particularly good storage stability. It is speculated that the complexing agent weakens the bond between the alkaline earth metal cation and the stearic acid residue through complexation of the alkaline earth metal cation in the alkaline earth metal stearate, thereby affecting the chemical and physical properties of the alkaline earth metal stearate. One hypothesis is that the complexation of the alkaline earth metal ion weakens the bond between the alkaline earth metal cation and the stearic acid residue, thereby enhancing the ionic properties of the alkaline earth metal stearate in combination with the complexing agent. This is thought to result in the alkaline earth metal stearate having a surfactant effect and / or improving the dispersibility of the alkaline earth metal stearate in water. This can be advantageous in producing a processing aid from the formulation.

[0064] In addition, the release agent or processing aid has good wettability. It can be assumed that the ionic character of the bond formed between the alkaline earth metal cation and the stearic acid residue caused by the action of the complexing agent leads to better surface wettability. Water-soluble alkali stearates are known to often lead to improved wettability.

[0065] In this case, improved wettability correlates with a greater number of connection sites between the release film and the respective surface. The greater the number of connection sites, the greater the likelihood that the release film will remain permanently attached during storage, i.e., under the influence of mechanical forces and environmental conditions such as p, T, and humidity, and therefore the greater the likelihood of improved storage stability.

[0066] The combination of alkaline earth metal stearate and complexing agent also allows this advantageous property to be achieved without the need for additional alkali stearate addition.

[0067] This is particularly advantageous because alkali stearates tend to be more foam-forming, whereas alkaline earth metal stearates, especially magnesium stearate, can be used as anti-foaming or even defoaming agents.

[0068] The release agent obtained from the formulation or from the processing aid according to the present disclosure ensures particularly good storage stability. This is manifested, inter alia, in the fact that the release agent film adheres well to the workpiece surface, with no or only few particles peeling off from the release agent film. It is assumed that the ionic properties of the alkaline earth metal stearate described above promote the adhesion or bonding of the alkaline earth metal stearate to the surface of the inorganic component of the release agent film. This, in turn, leads to improved deposition behavior of the processing aid on the workpiece surface and better embedding of the inorganic minerals in the organic matrix of the release agent, thereby increasing its mechanical resistance.

[0069] Thus, the complexing agent in the formulation disclosed herein not only serves as an auxiliary for the preparation of a processing aid by dispersing the formulation in water, but also favorably influences the properties of the release agent. The formulation contains at least 0.1% by weight, preferably at least 0.5% by weight, of the complexing agent. According to one embodiment, the proportion of the complexing agent in the formulation is in the range of 0.1 to 3% by weight, preferably in the range of 0.3 to 2% by weight, particularly preferably in the range of 0.5 to 1.5% by weight. The formulation may also contain a mixture of different complexing agents.

[0070] Furthermore, the inventors have confirmed that the complexing agent also enhances the storage stability of the formulation, which was also observed in powder formulations.

[0071] Typically, powdered formulations contain residual moisture in the range of 5-10% by weight, which is introduced by the moisture content of the individual ingredients. Therefore, it can be assumed that the complexing agent will already be complexed with the alkaline earth metal stearate in the formulation.

[0072] Due to the combination of inorganic minerals with the disclosed surface-affinity components, including alkaline earth metal stearates and complexing agents, the processing aids and corresponding release agents according to the present invention have particularly advantageous properties, especially with regard to their applicability.

[0073] According to one embodiment, the formulation for producing the processing aid comprises an inorganic swelling mineral, preferably a swelling silicate, and the ratio of the weight proportion of the inorganic swelling mineral to the weight proportion of the alkaline earth metal stearate and complexing agent in the active substance is: m (inorganic component) / (m (alkaline earth metal stearate) + m (complexing agent)) is in the range of 1 to 10, preferably 1.5 to 8.

[0074] One development provides that the complexing agent is a chelating agent that forms a 1:1 complex with alkaline earth metal cations, in particular calcium ions. Preferably, the complexing agent is at least tetracoordinate or at least hexacoordinate. The use of a multicoordinate complexing agent increases the stability of the complex consisting of alkaline earth metal stearate and complexing agent. In addition, the weight proportion of complexing agent in the formulation can be reduced. According to one embodiment, the molar ratio of alkaline earth metal stearate to complexing agent, n(alkaline earth metal stearate) / n(complexing agent), is in the range of 5 to 30, preferably in the range of 8 to 25, particularly preferably in the range of 9 to 20.

[0075] According to one embodiment, the formulation has a complexation constant pK for the formation of calcium complexes of at least 5.0, preferably at least 6.5, more preferably at least 7. CaKomplex and / or a complexation constant pK for the formation of magnesium complexes of at least 5 or at least 5.5 MgKomplex It has proven particularly advantageous to include a complexing agent having a complexation constant pK CaKomplex is in the range of 5.0 to 12, preferably in the range of 6.5 to 12, and particularly preferably in the range of 7 to 12.

[0076] Preferably, the formulation contains an aminopolycarboxylate salt as a complexing agent. The use of the corresponding sodium salt has been found to be particularly advantageous, since sodium salts usually have good water solubility. According to one embodiment, the formulation contains ethylenediaminetetraacetic acid (EDTA) and / or its sodium and / or potassium salts, which may also be referred to as ethylenediaminetetraacetic acid sodium salt or ethylenediaminetetraacetic acid potassium salt. Alternatively or additionally, according to a further embodiment, the formulation comprises methylglycine diacetate and / or a salt thereof, particularly its sodium salt, as a complexing agent. Methylglycine diacetate is a biodegradable complexing agent and is therefore particularly advantageous, particularly in terms of the environmental compatibility of the formulation. At the same time, methylglycine diacetate has high chemical stability, particularly high pH resistance, and thermal stability of at least 200°C.

[0077] One embodiment provides that the formulation comprises a biodegradable complexing agent. Preferably, all of the complexing agents contained in the formulation are biodegradable. The term "biodegradable complexing agent" is understood in the sense of the present invention to mean a complexing agent that meets the test guideline OECD 302 and / or test guideline OECD 301.

[0078] One development envisages that the formulation comprises at least one film-forming polymer. The use of a film-forming polymer can further reduce the formation of dust during the production of the release agent from the formulation. In addition, the adhesion of the release agent film to the rubber surface and / or the incorporation of inorganic components in the release agent film can be improved. The content of the film-forming polymer in the formulation is preferably in the range of 0.5 to 3.5% by weight, more preferably in the range of 1.5 to 3.0% by weight.

[0079] In one embodiment, the formulation contains a polysaccharide, particularly starch, as the film-forming polymer. In a further embodiment, the formulation contains polyvinyl alcohol (PVA). In this case, the film-forming polymer is contained in the formulation as a solid and can be uniformly dispersed therein.

[0080] One development is that the film-forming polymer is present as a separate component of the formulation. Thus, according to one embodiment, the container or packaging containing the formulation may consist of or contain a film-forming polymer. During the production of the release agent, in this development, the entire container can be placed in water. Thus, emptying the container is not necessary, which reduces time consumption and potential contamination of the manufacturing plant.

[0081] The formulation may contain further components, such as auxiliaries for adjusting the rheological properties of the release agent, such as flow agents. Alternatively or additionally, the formulation may, according to one embodiment, contain further auxiliaries, such as surfactants, in particular nonionic surfactants or fatty acid salts.

[0082] Within the scope of this disclosure, a surfactant is generally understood to be a substance that reduces the surface tension of a liquid, or more generally, the interfacial tension between two phases. It is usually an organic molecule containing a hydrophobic component and a hydrophilic component. In this case, the hydrophobic component is often a hydrocarbon residue, such as a long alkyl chain, and is generally non-polar or apolar. The hydrophilic component is generally polar, and may, for example, be ionic, but this is not necessarily the case. For example, a hydroxyl group may also form the polar component of the surfactant. Preferably, within the scope of this disclosure, the surfactant has a molar mass of up to 10,000 g / mol, particularly preferably when the surfactant and / or the mixture of at least two surfactants is formed from or contains an anionic surfactant.

[0083] Surface tension reducing agents or anti-foaming agents may also be components of the formulation.

[0084] The present invention further relates to a processing aid. The processing aid is a dispersion, in particular a suspension of the above-mentioned formulation in water, preferably fully demineralized water (VE water). The water content of the processing aid is preferably in the range of 85 to 99% by weight, particularly preferably in the range of 94 to 99% by weight. According to one embodiment, the pH value of the processing aid is in the range of 9 to 12.5, preferably in the range of 10 to 12.

[0085] According to one embodiment, the proportion of active substance in the formulation ingredients and / or processing aids is 0.5 to 5% by weight, preferably 1 to 4.5% by weight, particularly preferably 1.5 to 3.5% by weight.

[0086] The present invention will be described in detail below with reference to examples and FIGS. [Brief explanation of the drawings]

[0087] [Figure 1] FIG. 1 is a schematic diagram of the complexation of calcium stearate with EDTA. [Figure 2] 1 shows the effect of EDTA on the melting point of calcium stearate. [Figure 3] Figure 1 shows the effect of EDTA on the dispersibility of calcium stearate in water. [Figure 4] 1 shows the effect of EDTA on the pH value of dispersions containing magnesium stearate. DETAILED DESCRIPTION OF THE INVENTION

[0088] According to one embodiment, a formulation for producing a processing aid comprises the following ingredients in weight percent: Calcium stearate 10-32% by weight Calcium carbonate 6-22% by weight Kaolin 3-18% by weight Tetrasodium ethylenediaminetetraacetic acid 0.8-1.4% by weight Alcohol C12-14, propoxylated 3-10% by weight Alcohol C9-11 iso, C10 rich, ethoxylated 0-4 wt% Sodium di(ethylhexyl) sulfosuccinate 0-3% by weight

[0089] The molar ratio of calcium stearate to tetrasodium ethylenediaminetetraacetate is preferably in the range of 10:1 to 33:1.

[0090] The processing aid can be obtained by dispersing the formulation in water. According to one embodiment, the proportion of the formulation in water is 0.5 to 5% by weight, preferably 1 to 4.5% by weight, particularly preferably 1.5 to 3.5% by weight.

[0091] Figure 1 shows a schematic diagram of the effect of complexing agents on calcium stearic acid, an example of an alkaline earth metal stearate. Unlike alkali stearates such as sodium stearate, in calcium stearate, the covalent bond between the carboxyl group and the calcium cation (shown by the dashed line) is significantly higher than the ionic portion. Therefore, the carboxyl group of the fatty acid anion can accept little or no protons at neutral pH. Accordingly, calcium stearate has little or no basicity. Due to the covalent nature of the bond between the stearate anion and the calcium cation, calcium stearate is largely nonpolar. Accordingly, calcium stearate is insoluble in water and has little or no surfactant properties.

[0092] By adding a complexing agent to form a calcium complex, the calcium cations are complexed (indicated by the arrow), thereby weakening the bond between the stearate anions and the calcium cations. As a result, calcium stearate, in conjunction with the complexing agent, has stronger ionic properties. Corresponding considerations can be applied to other alkaline earth metal stearates, especially magnesium stearate.

[0093] Figures 1 to 3 clearly show the influence of complexing agents on the chemical and physical properties of calcium and magnesium stearates. For this purpose, model systems of dispersions consisting of calcium or magnesium stearate and surfactants in water were mixed with different contents of complexing agent. In this case, an aqueous solution containing 4% by weight of surfactant was prepared and mixed with 10% by weight of an alkaline earth metal stearate. To the dispersions thus obtained, the contents of complexing agent indicated on the x-axis were added.

[0094] In this case, Figure 2 shows the effect of a complexing agent on the melting point of calcium stearate. For this, water was removed from the dispersion described above and the melting point of the solid was determined. Figure 2 shows the effect of EDTA (used as its sodium salt) on the melting point. The melting point of the mixture of surfactant and calcium stearate without a complexing agent is 120°C, while the melting point of pure calcium stearate is 158°C. The decrease in melting point due to the addition of a surfactant can be explained by the melting point depressant effect on the mixture.

[0095] Since the melting point depression effect is a synergistic effect, when a complexing agent is added as an additional component in the mixture, a further decrease in melting point would be expected with increasing complexing agent content. However, it is clear from Figure 1 that the addition of a complexing agent also leads to an increase in melting point. This is speculated to be due to the increased ionic character of calcium stearate due to complexation of calcium ions by the added complexing agent. For example, the melting point of stearates is known to increase with increasing ionic character. Pure sodium stearate, a water-soluble soap, has a melting point of 205°C. In contrast, the melting points of less polar stearates of calcium and magnesium are 158°C and 140°C, respectively. The lower melting point of magnesium stearate compared to calcium stearate can be explained by the stronger covalent bond between magnesium and the stearic acid residue. Therefore, the addition of a complexing agent can enhance and / or broaden the melting range of the release agent film. In particular, broadening the melting range is advantageous here. This is because uniform application of the release agent can be ensured over a wide temperature range, especially due to the melting of the stearate portion.

[0096] Figure 3 shows the effect of a complexing agent on the dispersibility of calcium stearate. To this end, 200 ml of dispersion was prepared and the sediment volume was determined. NaEDTA was used as the complexing agent. The sediment volume is an indicator of the dispersibility of water-insoluble calcium stearate. A well-dispersed mixture has only a small amount of sediment. Curve 1 shows the effect of NaEDTA on the sediment volume in distilled water, and curve 2 shows the effect of EDTA on the sediment volume in tap water. From Figure 3, it is clear that the sediment volume decreases with increasing complexing agent content. Therefore, it is assumed that the polar character of calcium stearate is enhanced by calcium complexation, improving its dispersibility in water. Thus, dispersibility is enhanced by the addition of a complexing agent. At the same time, as the concentration of the complexing agent increases, the influence of water quality (e.g., water hardness) on the sediment volume or dispersibility decreases. This is advantageous. This is because reproducible dispersibility can be guaranteed regardless of the water quality used to produce the processing aid from the formulation.

[0097] Figure 4 shows the effect of a complexing agent on the pH of a dispersion consisting of a surfactant and magnesium stearate. Here, we can see the increase in pH with increasing complexing agent concentration, which increases sharply up to a concentration of 0.5 wt.% and then plateaus. Curve 3 shows the effect of NaEDTA on the pH in tap water, and curve 4 shows the effect of NaEDTA on the pH in distilled water. In the example shown in Figure 4, the molar ratio of magnesium stearate to complexing agent at a concentration of 0.5 wt.% EDTA is 13. The curves shown in Figure 4 can be explained by the weakening of the bond between the alkaline earth metal cation and the stearic acid residue upon addition of the complexing agent. This increases the ionic character of the carboxyl group, which is manifested as a decrease in the pKb value and, therefore, an increase in the basicity of the stearic acid residue. The plateaus shown in curves 3 and 4 indicate that above a certain ratio of stearate to complexing agent, the basicity of the stearate residue does not increase further, or at least does not increase sharply.

Claims

1. A formulation for producing a processing aid comprising an active substance having a surface-affinity component and an inorganic component, wherein the inorganic component comprises at least one inorganic mineral, and the surface-affinity component comprises at least one alkaline earth metal stearate and a complexing agent for forming an alkaline earth metal complex, wherein the proportion of the inorganic component in the active substance of the formulation is 3 to 92% by weight, the proportion of the alkaline earth metal stearate in the active substance of the formulation is 5 to 50% by weight, and the proportion of the complexing agent in the active substance of the formulation is 0.1 to 3% by weight.

2. 2. The formulation according to claim 1, wherein the formulation comprises as alkaline earth metal stearate at least one magnesium and / or calcium salt of an alkanoic acid, n-hexadecanoic acid, n-heptadecanoic acid and / or n-octadecanoic acid, preferably at least one calcium salt of an alkanoic acid, n-hexadecanoic acid, n-heptadecanoic acid and / or n-octadecanoic acid.

3. 3. A formulation according to claim 2, wherein the proportion of alkaline earth metal stearates in the active substance is between 9 and 50% by weight, preferably between 9 and 35% by weight.

4. 4. The formulation according to claim 1, wherein the inorganic mineral comprises a swelling mineral, an inorganic carbonate, kaolin and / or talc, preferably a swelling phyllosilicate, particularly preferably smectite, montmorillonite, stevensite, sepiolite and / or mixtures thereof.

5. The formulation according to any one of claims 1 to 4, wherein the ratio of the weight proportion of the inorganic component to the weight proportion of the surface-affinity component in the active substance is 0.05 to 18, preferably 0.5 to 11, particularly preferably 1 to 9.

6. A formulation according to any one of claims 1 to 5, wherein the active substance component is stable to temperatures of at least 160°C, preferably at least 200°C.

7. The formulation according to any one of claims 1 to 6, wherein the formulation comprises a chelating agent as a complexing agent, preferably at least a tetracoordinate chelating agent.

8. The complexing agent contained in the formulation forms a 1:1 chelate complex with calcium cations, and the complex formation constant pK CaKomplex 8. The formulation according to claim 7, wherein is ≧5.0, preferably ≧6.5, particularly preferably ≧7.

9. 9. The formulation according to claim 7 or 8, wherein the formulation comprises as complexing agent an aminopolycarboxylate or an alkali salt thereof, preferably methylglycine diacetic acid or ethylenediaminetetraacetic acid, particularly preferably methylglycine diacetic acid.

10. Formulation according to any one of claims 1 to 9, wherein the complexing agent is biodegradable, in particular biodegradable according to OECD 302 or OECD 301.

11. 11. The formulation according to any one of claims 7 to 10, wherein the molar ratio of alkaline earth metal stearate to complexing agent is in the range of 5 to 30, preferably in the range of 8 to 25, particularly preferably in the range of 9 to 20.

12. 12. The formulation according to any one of claims 1 to 11, wherein the inorganic component comprises an inorganic carbonate, preferably calcium carbonate, and the content of inorganic carbonate in the active substance is preferably in the range of 3 to 75 wt. %, particularly preferably in the range of 10 to 55 wt. %, most preferably in the range of 10 to 20 wt. %.

13. A formulation according to any one of claims 1 to 12, wherein the formulation is present as an aqueous dispersion with a water content of 40 to 85% by weight.

14. The formulation according to any one of claims 1 to 13, wherein the formulation comprises a film-forming polymer, preferably starch and / or polyvinyl alcohol (PVA).

15. 15. A formulation according to claim 14, wherein the film-forming polymer is present as a separate component of the formulation, preferably as a component of the container or packaging in which the formulation is contained.

16. 16. A processing aid for polymers or polymer intermediates, comprising the formulation according to any one of claims 1 to 15 and water, wherein the components of the formulation are dissolved and / or dispersed in water, and the proportion of the active substance of the formulation in the processing aid is 0.5 to 5% by weight, preferably 1 to 4.5% by weight, particularly preferably 1.5 to 3.5% by weight.

17. A processing aid according to claim 16 and / or a release agent produced or preparable from a formulation according to any one of claims 1 to 15.

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