Method for the manufacture of electrically insulating protective gloves with arc protection and such protective gloves

Abstract

The invention relates to a method for the manufacture of electrically insulating protective gloves with arc fault protection based on thermoplastic elastomers in combination with a pigment. Said method is carried out, in particular, without vulcanisation. The invention also relates to said type of protective gloves.

Description

[0001] METHOD FOR MANUFACTURING ELECTRICALLY INSULATING PROTECTIVE GLOVES

[0002] WITH ARC FLASH PROTECTION AND SUCH PROTECTIVE GLOVES

[0003] TECHNICAL FIELD

[0004] The invention relates to a process for producing electrically insulating protective gloves with arc protection based on thermoplastic elastomers in combination with a pigment. The process is carried out, in particular, without vulcanization. The invention further relates to such protective gloves.

[0005] TECHNICAL BACKGROUND

[0006] Currently, protective gloves against electrical discharge are typically made of natural rubber or synthetic polyisoprene. For practical use, electrically insulating protective gloves must meet requirements specified in relevant standards, such as the European standard IEC 60903:2014 and the US standard ASTM D120-21. According to the above standards, electrically insulating protective gloves are divided into classes and sizes. The lengths are also specified by the aforementioned standards. Table 1 below details the respective classes and corresponding values ​​for the maximum operating voltage in volts and the test voltage in volts according to IEC and ASTM.

[0007] Class Length Maximum operating voltage Test voltage in [mm] in Volt in Volt

[0008] 00 280 / 360 mm 500 V 2500 V

[0009] 0 280 / 360 / 410 / 460mm 1000V 5000V

[0010] 1 360 / 410 / 460mm 7500V 10 000V

[0011] 2 360 / 410 / 460mm 17,000V 20,000V

[0012] 3 360 / 410 / 460mm 26 500V 30 000V

[0013] 4 410 / 460 mm 36 000 V 40 000 V

[0014] Table 1: Protection class classification and corresponding requirements for electrically insulating protective gloves according to IEC and ASTM.

[0015] In addition to the ability to prevent electrical discharges, electrically insulating protective gloves also have to meet certain mechanical requirements such as tensile strength, for example > 16 N / mm 2(MPa); elongation at break, e.g., > 600%; permanent elongation (deformation resistance), e.g., < 15%; puncture resistance, e.g., > 18 N; as well as resistance to the spread of fire, e.g., no flame spread after 55 seconds of fire exposure, and cold resistance. In addition, electrically insulating protective gloves should generally also be resistant to the spread of heat, oil, ozone, acids, and extremely low temperatures.

[0016] The standards mentioned also specify the thickness (material thickness, wall thickness) of the electrically insulating protective gloves for practical use at certain discharge intensities, for example a maximum wall thickness of 0.50 mm is permitted for class 00, a maximum wall thickness of 1.00 mm for class 0, a maximum wall thickness of 1.50 mm for class 1, a maximum wall thickness of 2.30 mm for class 2, a maximum wall thickness of 2.90 mm for class 3 and a maximum wall thickness of 3.60 mm for class 4.

[0017] Due to their material properties, natural rubber and synthetic polyisoprene are currently the only materials that meet the requirements of common standards for electrically insulating protective gloves.

[0018] In addition to the requirements already mentioned, arc resistance is increasingly required for electrically insulating protective gloves in practical use, as arcs can occur when working with electrical current and, triggered by short circuits, manifest themselves as a continuous discharge of high voltage in the air between two electrodes. The consequences can be burns to the skin and body due to extreme heat development. Arc faults can also cause fires. Arc explosions with pressure waves of up to 1000 kg / m 2 can cause serious injuries. Sound waves up to 140 dB and ultraviolet light can cause hearing and eye damage.

[0019] Common processes for manufacturing electrically insulating protective gloves made of natural rubber and synthetic polyisoprene have in common that they generally involve vulcanization. However, the vulcanization process has significant disadvantages. Vulcanization is energy-intensive. Protective gloves vulcanized with sulfur may contain allergenic components. Furthermore, allergens may also be present in natural rubber itself. Due to the chemical changes that occur during vulcanization, the glove material cannot be reused or recycled for the manufacturing process.

[0020] In view of the aforementioned disadvantages of conventional methods, it is an object of the present invention to provide a method for producing electrically insulating protective gloves with arc flash protection that is energy-efficient, does not use or generate allergenic components, and allows waste material generated during production or gloves produced using the method to be recycled back into the manufacturing process. Furthermore, the electrically insulating protective gloves with arc flash protection should meet the requirements of common standards.

[0021] SOLUTION TO THE PROBLEM

[0022] The object is achieved with the features of independent claims 1 and 16. The dependent claims are directed to preferred embodiments of the invention.

[0023] According to the invention, a method for producing electrically insulating protective gloves with arc fault protection (hereinafter also referred to as protective gloves or gloves) initially comprises the step of providing a starting material. The starting material essentially consists of two thermoplastic elastomers. In other words, the starting material essentially consists of a mixture of two thermoplastic elastomers.

[0024] The term "consisting essentially of" is to be interpreted herein as being nearly complete, but does not preclude the possibility that a few additional components, as described herein, may be added to the starting material.

[0025] Thermoplastic elastomers are polymers, usually so-called copolymers, whose chains are designed to have the following three properties:

[0026] Thermoplastic elastomers can be stretched to moderate elongation and the structure returns virtually to its original shape when the load is removed;

[0027] • Thermoplastic elastomers can be processed easily at elevated temperatures; and

[0028] • Thermoplastic elastomers are characterized by interactions of a physical nature.

[0029] Thermoplastic elastomers (TPEs) represent a distinct class of materials. In terms of their properties and processing capabilities, they lie between thermoplastics and elastomers. TPEs combine the processing properties of thermoplastics, such as deformability through heat application, with the softness and flexibility of elastomers. By producing polymer mixtures or blends, the properties of TPE materials can be specifically controlled, for example, by having one of the polymer components contribute predominantly the elastic properties to the resulting compound, while the other(s) contribute more the thermoplastic properties. This aspect is utilized in the present invention by the starting material essentially consisting of a mixture of two thermoplastic elastomers.

[0030] The use of TPEs offers numerous advantages over conventional materials. For example, the use of TPEs eliminates the need for latex, polyvinyl chloride (PVC), phthalates, or heavy metals, thus eliminating the need for allergenic ingredients.

[0031] According to the invention, the thermoplastic elastomers used are fundamentally unrestricted in terms of their structure. However, TPEs with styrene block copolymers (SBCs), which are generally referred to as TPE-S or TPS, are preferred. The most common types of SBCs include:

[0032] - SBS: styrene-butadiene-styrene block copolymer;

[0033] - SIS: Styrene-isoprene-styrene block copolymer;

[0034] - SEBS: Styrene-Ethylene-Butylene-Styrene Block Copolymer and

[0035] - SEPS: Styrene-ethylene-propylene-styrene block copolymer.

[0036] The inventors have discovered that the properties of SEBS-based thermoplastic elastomers are particularly advantageous for the production of electrically insulating protective gloves with arc flash protection. SEBS-based thermoplastic elastomers exhibit very good elasticity and flexibility, as well as outstanding mechanical properties such as tensile strength, elongation at break, permanent elongation, puncture resistance, and tear strength. SEBS-based thermoplastic elastomers can be made translucent and transparent. This allows for a wide range of coloring options. SEBS-based thermoplastic elastomers also offer a broad spectrum of potential additive applications, particularly for pigments and dyes.In addition, materials made from SEBS-based thermoplastic elastomers offer properties that are also very important for additional categories and requirements in the practical application of electrically insulating protective gloves. SEBS-based thermoplastic elastomers offer greater temperature stability than thermoplastics, which is particularly important for arc flash protection with regard to heat generation. SEBS-based thermoplastic elastomers are elastic at low temperatures down to -40°C, thus allowing resistance to extreme cold. SEBS-based thermoplastic elastomers exhibit excellent resistance to UV radiation, ozone, and weathering, especially to oxidative environments.SEBS-based thermoplastic elastomers are resistant to oils and greases at high temperatures, as well as to high-temperature barrier fluids and water-based solutions, such as acids. According to a preferred embodiment, the two thermoplastic elastomers can therefore be, in particular, styrene-ethylene-butylene-styrene (SEBS)-based thermoplastic elastomers. This means that the starting material can preferably consist essentially of a mixture of two styrene-ethylene-butylene-styrene (SEBS)-based thermoplastic elastomers.

[0037] The mixture preferably consists essentially of a first SEBS-based component and a second SEBS-based component. The first SEBS-based component preferably has a molecular structure of 50-200 units and a polystyrene content of approximately 12-15%. The first component therefore preferably exhibits high elastic properties, which are reflected in high elongation. The second SEBS-based component preferably has a molecular structure of 50-200 units and a polystyrene content of 30-35%. The second component therefore preferably exhibits high mechanical resistance and thus high tensile strength values. By combining the two components, the properties of the starting material can be specifically adjusted using the individual properties of the two thermoplastic elastomers.

[0038] According to a further preferred embodiment, the starting material can additionally consist of a styrene-based polymeric auxiliary component. The styrene-based polymeric auxiliary component is preferably SBS, SIS, SEBS, SEPS, or a mixture of these components; more preferably, the styrene-based polymeric auxiliary component is SBS or SEBS, or a mixture of the two. The styrene-based polymeric auxiliary component preferably has a molecular structure of between 50 and 200 units and a polystyrene content of more than 50%. The auxiliary component can be present in the starting material in a smaller amount. Its function is to improve the properties of the previous two components, for example, by reinforcing the hard spots of the polymeric mixture, thereby increasing structural stability.In this way, products with high values ​​in relation to the standard requirements can be obtained without the need for a vulcanization process.

[0039] Particularly preferred is a three-component compound as the starting material, consisting of two SEBS-based thermoplastic elastomers and a styrene-based polymeric auxiliary component. The hardness of the compound is particularly preferably in the range of 30 to 60 Shore A (DIN ISO 7619-1), 47 Shore A (DIN ISO 48-4). The density of the compound is preferably 0.940 g / cm³. 3(DIN EN ISO 1183-1). The tensile strength is preferably 14 MPa (DIN 53504 / ISO 37). The elongation at break is preferably 550% (DIN 53504 / ISO 37), and the tear strength is preferably 38 N / mm (DIN ISO 34-1, Method B(b) (Graves)). One such compound is available, for example, under the name Thermoplast® K, TF5TAA from the FC / ADl / ht series of Kraiburg TPE GmbH & Co. KG.

[0040] According to the invention, a method for producing electrically insulating protective gloves with arc flash protection further comprises the step of dissolving the starting material in an organic solvent to produce a liquid mixture (in the sense of a solution).

[0041] According to the invention, the organic solvent is not fundamentally restricted. However, according to a preferred embodiment, the organic solvent can be, in particular, toluene.

[0042] According to a further preferred embodiment, in the step of dissolving the starting material in the organic solvent, a liquid mixture of 10-50% w / w based on the proportion of the starting material in the organic solvent can be produced, particularly preferably 20-35% w / w. The proportion of the starting material in the organic solvent influences the viscosity of the resulting mixture and thus offers a possibility of controlling the layer thickness of the material layer resulting from a dipping step in the dipping process described below. Likewise, the proportion of the starting material in the organic solvent influences the stability of the dispersion described below, so that the proportion can be adjusted according to the desired stability.

[0043] According to the invention, a method for producing electrically insulating protective gloves with arc flash protection further comprises the step of dispersing a pigment in the liquid mixture to produce a dispersion. The pigment can be added during the dissolution process of the starting material. The pigment can be completely and efficiently dispersed. The resulting dispersion is stable for a period of 10-48 hours and is thus sufficiently stable for the duration of the manufacturing process. In this way, a consistent production quality of the protective gloves can be ensured.

[0044] According to a preferred embodiment, in the step of dispersing the pigment in the liquid mixture, a dispersion of 0.5-10% m / m based on the proportion of the pigment in relation to the starting material can be prepared, preferably 0.5-5% m / m, particularly preferably 0.5-2.5% m / m.

[0045] In principle, the technical requirements for the production of protective gloves for electrical applications are so high that materials that do not have polyisoprene-based polymer structures have not been able to be used to date. However, the inventors have advantageously discovered that by matching the physicochemical and mechanical properties of the two thermoplastic elastomers, in particular the SEBS-based thermoplastic elastomers, together with the addition of the pigment in concentrations of 0.5-10% w / w, not only the properties required for electrical, mechanical, and physicochemical protection can be achieved, but also thermal protection. Thus, the protective gloves produced using the process according to the invention not only meet the requirements of protection classes 00 to 4 according to current standards, but also offer arc flash protection according to the protection classes described herein.

[0046] The pigment is not fundamentally restricted according to the invention. According to a preferred embodiment, the pigment can be an organic pigment. The pigment can also be fundamentally unrestricted in terms of color. However, the pigment can preferably be a blue pigment. The pigment can, in particular, be copper phthalocyanine. For example, copper phthalocyanine alpha stab. (CAS No.: 147-14-8) with a specific surface area of ​​62 m 2 / g and a density of l.6g / cm 3 This pigment is available in powder form from BASF SE, for example, under the name Heliogen® Blue K 6907.

[0047] In the interest of sustainability, according to a preferred embodiment of the process, at least a portion of the starting material and the pigment can be replaced by waste material generated in the process and / or protective gloves produced using the process. The protective gloves produced from TPEs and pigment can be dissolved in the organic solvent as described herein and reused without significantly losing their physical, chemical, and mechanical properties. In the case of partial replacement, starting material and pigment are additionally added according to the ranges for the liquid dispersion described herein. In this way, the gloves produced and used once can be collected and used for the production of new gloves.The same applies to gloves that accrue during the production process and can be immediately returned to the production process, thus eliminating solid waste. The reuse of raw materials is particularly important in the production of safety items, such as electrically insulating gloves, which have high technical requirements and a high incidence of defective batches.

[0048] According to the invention, a method for producing electrically insulating protective gloves with arc flash protection further comprises the step of providing at least one mold suitable for producing protective gloves. For example, a mold in the form of a fully anatomical model of a forearm with a hand is suitable for producing protective gloves. In particular, two or more molds can also be used, for example, fully anatomical models of a right and a left forearm with a hand.

[0049] According to the invention, the material of the at least one mold is not fundamentally limited. The mold can be made of ceramic or metal, for example, but preferably the at least one mold is a ceramic mold.

[0050] The number of molds that can be used simultaneously to produce electrically insulating protective gloves in the process according to the invention is not limited and will certainly depend on process-related capacities or be selected accordingly. For example, between 96 and 140 molds can be used simultaneously.

[0051] According to a preferred embodiment, the at least one mold can have a predetermined surface finish. The surface finish of the mold can be used to specifically adjust the feel of the electrically insulating protective gloves. In particular, the surface of the at least one mold can be smooth or rough. The term "rough" is to be interpreted broadly herein. The term "rough" can be understood, for example, as sandpaper-like or abrasive paper-like. In this sense, the surface finish of the at least one mold can also have various degrees of roughness, corresponding, for example, to a grain size in the range of >600 μm to 18 μm. In other words, the surface finish of the at least one mold can have a surface finish selected from the group consisting of smooth, very finely roughened, finely roughened, medium roughened, and coarsely roughened.

[0052] Before performing the dipping process described below, the method can optionally additionally include the step of conditioning the viscosity, solid mass, and / or temperature of the dispersion. In other words, the viscosity, solid mass, and / or temperature of the dispersion can be adjusted according to the prevailing process conditions, such as ambient temperature and humidity, in order to ensure consistent quality of the protective gloves produced. Preferred ranges can be, for example, viscosity: 10-80 s, preferably 10-60 s, measured at 25+1 °C using the Ford cup method; dry matter content: 20-45% w / w; and temperature: 20-30 °C.

[0053] The method may also optionally additionally comprise the step of preparing the at least one mold comprising the steps of: i) cleaning the at least one mold, for example with toluene; ii) applying a release agent, for example petroleum spirit; and iii) conditioning the at least one mold for the dipping process.

[0054] Depending on the material and nature of at least one mold, applying a release agent can facilitate the subsequent removal of the produced protective gloves.

[0055] The method can also optionally include the additional step of preparing a tank for the dipping process. The size of the tank is not fundamentally limited according to the invention and will generally depend on the given process-related capacities, for example, the number of molds used.

[0056] According to the invention, a method for producing electrically insulating protective gloves with arc fault protection further comprises the step of performing a dipping process. A dipping process comprises at least one cycle consisting of a dipping step, in which, in an immersion phase, the at least one mold is completely immersed in the dispersion and, in a removal phase, is completely removed from the dispersion to form a material layer on the mold; and a drying step to remove the organic solvent from the material layer.

[0057] The described dipping process is a purely physical dipping process. This means that no thermal or chemical process is required for the dipping, such as thermosensitive dipping or the addition of coagulants, thus advantageously reducing energy consumption and the use of chemical components in the manufacturing process.

[0058] According to a preferred embodiment, the dipping process can consist of 1-50 cycles, preferably 5-20 cycles. The number of cycles can advantageously be used to adjust the wall thickness of the protective gloves, since in each cycle, a further layer of material forms superimposed on the at least one mold. Furthermore, the thickness of the individually formed material layers can also be controlled by the dipping speed.

[0059] According to a further preferred embodiment, in the dipping step, the at least one mold can be immersed into the dispersion at a predetermined speed in the dipping phase and removed from the dispersion at a predetermined speed in the discharging phase.

[0060] According to a further preferred embodiment, the at least one mold can be constantly rotated during the drying step. This enables a uniform distribution of the material mixture over the surface of the mold and thus the formation of a uniformly thick material layer.

[0061] According to a particularly preferred embodiment, the at least one mold can be rotated during the drying step at a predetermined rotational speed and / or rotational velocity. The rotational velocity can be, for example, 20-30 s / revolution, preferably 25 s / revolution.

[0062] According to a further preferred embodiment, the drying step can be carried out for a duration of 20-60 minutes.

[0063] The process according to the invention for producing electrically insulating protective gloves with arc flash protection may optionally further comprise the step of evaporating remaining solvent residues after the dipping process.

[0064] And the method according to the invention for producing electrically insulating protective gloves with arc flash protection further comprises the step of removing the protective glove thus formed from the at least one mold.

[0065] According to a preferred embodiment, the process according to the invention can be carried out without vulcanization. This is because the thermoplastic elastomers (TPEs) used in the process exhibit the viscoelastic properties typical of elastomers without requiring vulcanization. Eliminating a vulcanization process has the advantage that the energy typically required to generate pressure and temperature in the autoclave is not required. Since the vulcanization process is eliminated, the energy consumption in the process according to the invention is significantly lower than in conventional processes with a vulcanization process.

[0066] The elimination of vulcanization has the additional advantage that, since the material does not contain typical cross-linking compounds, it can be easily reused and processed to obtain its original shape or new products, either by temperature forming or by redissolving in organic solvent, as used for the manufacture of the protective gloves described herein.

[0067] The invention described herein further relates to an electrically insulating protective glove with arc flash protection. The electrically insulating protective glove with arc flash protection consists essentially of two thermoplastic elastomers based on styrene-ethylene-butylene-styrene (SEBS) and an organic pigment, in particular Cu phthalocyanine, as described herein.

[0068] According to a preferred embodiment, the protective glove may further consist of a styrene-based polymeric auxiliary component as described herein.

[0069] According to a further preferred embodiment, the electrically insulating protective glove with arc flash protection can also meet the requirements of standard classes 00 to 4 according to IEC 60903:2014. Reference to the currently valid standard IEC 60903:2014 does not preclude the possibility of meeting the requirements of future amendments to this standard. The electrically insulating protective glove with arc flash protection also meets the requirements of arc flash protection according to the protection classes described herein. The electrically insulating protective glove is obtainable by the inventive method described herein.

[0070] SHORT DESCRIPTION OF THE CHARACTERS

[0071] Figure 1 shows the results of a tensile strength test on a protective glove made of TPEs and pigments produced using the process according to the invention (Jung Gummitechnik's internal laboratory). The curve corresponds to the stress at elongation under the conditions described in the IEC 60903:2014 standard.

[0072] Figure 2 shows the result of a test of the arc fault protection of Class 00 protective gloves to Class APC 1 on protective gloves made of TPEs and pigment produced using the process according to the invention (standard test according to IEC 61482 - 1-2, tested at West Energie in Dortmund).

[0073] DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0074] Examples and exemplary embodiments of the present invention are described below with reference to the accompanying figures. It should be emphasized, however, that the present invention is in no way limited or restricted to the exemplary embodiments described below and their implementation features, but rather further encompasses modifications of the exemplary embodiments, in particular those that are encompassed by modifying the features of the described examples or by combining individual or multiple features of the described examples within the scope of the claims.

[0075] A first embodiment of the present invention is described in more detail below. The inventive method for producing electrically insulating protective gloves with arc flash protection is based on a dipping process without a vulcanization process, in which the dipping step is also purely physical, ie, a mold is immersed in a dispersion at least once and then removed again.

[0076] In this first embodiment, a compound of two SEBS-based thermoplastic elastomers and a styrene-based polymeric auxiliary component is provided as starting material for producing the electrically insulating protective gloves with arc flash protection, preferably Thermoplast® K TF5TAA from the FC / ADl / ht series of the manufacturer Kraiburg TPE GmbH & Co KG.

[0077] The starting material is a solid mixture and is dissolved in toluene to produce a liquid mixture, a solution, of 10-50% w / w based on the proportion of the starting material in toluene, particularly preferably 20-35% w / w.

[0078] The organic blue pigment Cu phthalocyanine, preferably Heliogen® Blue K 6907 from BASF SE, is dispersed in the liquid mixture (solution), producing a dispersion of 0.5-10% w / w based on the proportion of blue pigment in relation to the starting material, preferably 0.5-5% w / w, particularly preferably 0.5-2.5% w / w. The pigment can be added and dispersed while the starting material is being dissolved in toluene. The dispersion is stable for 10-48 hours. "Stable" here means that the dispersion does not separate into its components, i.e., that the pigment does not settle.

[0079] Subsequently, a tank is prepared and positioned for the dipping process, into which the dispersion is placed. Likewise, at least one ceramic mold in the shape of a fully anatomical model of a forearm with hand is prepared and positioned. The at least one ceramic mold can first be cleaned with toluene, then petroleum ether can be applied as a release agent, and the at least one ceramic mold can be conditioned in the dipping machine intended for the dipping process. The surface of the at least one ceramic mold can be rough or smooth, as described, depending on the desired feel of the electrically insulating protective gloves.

[0080] The prepared dispersion can be conditioned with regard to viscosity, solid mass and / or temperature before the dipping process, as already described.

[0081] Then, one or more dipping parameters for the dipping process are defined, e.g., the number of cycles, the speed of dipping the mold into the dispersion, the speed of withdrawing the mold from the dispersion, the number of revolutions with which the mold is to be rotated during the drying process, and the drying time between dipping steps.

[0082] In this first embodiment, the dipping process consists of 10 cycles, each consisting of a dipping step in which, in the dipping phase, the mold is completely immersed in the dispersion and, in the de-immersion phase, the mold is completely removed from the dispersion to form a material layer on the mold; and a drying step to remove the toluene from the material layer.

[0083] The drying step is carried out for 30 minutes between each dipping step, with the ceramic mold constantly rotating during drying. This means that once the ceramic mold has been removed from the dispersion, for example, by 180° around its longitudinal axis, it is constantly rotated to achieve a uniform surface distribution of the material. The number of rotations during the drying time depends, among other things, on the viscosity of the dispersion and the temperature. In this embodiment, the mold is rotated at a rotation speed of 25 s / revolution, preferably at ambient temperature, for example, between 16°C and 30°C.

[0084] After the dipping process, the mold, now coated with several overlapping layers of material, is removed from the dipping system and, optionally, any remaining toluene is evaporated, preferably at ambient temperature, for example, between 20 °C and 35 °C. The protective glove formed on the mold is then removed from the ceramic mold, for example, manually.

[0085] The electrically insulating protective gloves with arc flash protection produced in this way are then subjected to edge adjustment, electrical and mechanical properties testing, and quality assessment, for example, by visual means. The gloves can then be labeled and packaged.

[0086] The protective gloves produced using the method according to the invention can have a surface corresponding to the surface texture of the at least one mold. The different surfaces of the protective gloves each enable a more specific performance of tasks. The roughness, for example, improves grip and thus enables the performance of certain tasks that would be difficult with smooth gloves.

[0087] The protective gloves produced using the process according to the invention also meet the standard requirements corresponding to protection classes 00, 0, 1, 2, 3 and 4, i.e. maximum operating voltages of 500 V to 36,000 V and test voltages of 2,500 V to 40,000 V.

[0088] In a second embodiment, instead of the starting material and the pigment described in the first embodiment, waste material generated in the process and / or recycled protective gloves produced by the process are used, for example the protective gloves produced according to embodiment 1. In this case, the starting material and the pigment can then be completely or partially replaced by the waste material and / or by the gloves produced by the process by dissolving or dispersing the waste material and / or the gloves in toluene. In the case of partial replacement, starting material and pigment are additionally added according to the ranges for the liquid dispersion described herein. The subsequent process steps are the same and as already described herein in embodiment 1.

[0089] The use of the material in the dissolution steps for the new glove production has been extensively tested, and the results are excellent. The gloves produced exhibit no loss of relevant properties, neither electrical, mechanical, nor physico-chemical, even after multiple reuse steps.The following Table 2 shows the results of comparative tests on protective gloves made of pure natural rubber (average values ​​of products available on the market), on electrically insulating protective gloves according to the invention with arc protection made of new TPE material and pigment (as described, for example, in Example 1 with a proportion of 0.5% pigment based on the TPE mass), and on electrically insulating protective gloves according to the invention with arc protection made of reused material (made from internal rejects, as described, for example, in Example 1 with a proportion of 0.5% pigment based on the TPE mass).

[0090] As can be seen from the data in Table 2, both the inventive electrically insulating protective gloves made of virgin TPE material and pigment, as well as the inventive electrically insulating protective gloves made of reused material, meet the requirements of the IEC 60903:2014 standard. Furthermore, the properties of the inventive electrically insulating protective gloves are in some cases even better than those of conventional electrically insulating protective gloves made of natural rubber.

[0091] Table 2: Results of comparative tests (Jung Gummitechnik internal laboratory)

[0092] Figure 1 also shows the behavior of an approximately 0.5 mm thick sample of the inventive material made of TPEs and pigment, with a pigment content of 0.5% by mass, during the tensile strength test. This test provides information on tensile strength and elongation.

[0093] The test consists of preparing the specimen to the desired thickness in the format described in IEC 60930. After being loaded into the test apparatus, the specimen is subjected to elongation until breakage. The maximum tensile strength and the elongation of the specimen until breakage (break, see Figure 1) are then recorded.

[0094] A good viscoelastic material is characterized by a balanced relationship between tensile strength and elongation. In polymeric compounds resulting from the combination of different polymer structures, this property can be achieved through a balance between the polymers used. The presence of poorly dispersed substances can severely impair the achievement of a good balance of properties. The behavior observed in the sample shows that at the beginning of the force application, the material exhibits lower tensile strength with higher elongation, which is typical for elastomers. Shortly before the sample fractures, the curve rises to higher tensile resistance values. The relationship between tensile strength and elongation is therefore balanced in the glove material according to the invention.

[0095] Currently, arc flash tests are not yet fully adapted to the requirements of protective gloves, which means there is no specific standard for certification. However, the GS-ET-42-1 test principle exists to determine the protective potential of gloves against arcs. This method uses the basic system conditions for directed exposure of the box test procedure according to IEC 61482-1-2. The results are classified according to classes, with the classes being defined, among other things, by the arc current in kA, the arc duration in ms, the average arc energy in kJ, and the average incident energy in kJ / m 2The distance of the samples from the arc corresponds to 300 mm. The classes are divided as follows: Class 1 (Arc Protection Class, APC 1): 4 kA, 500 ms, 168 kJ; Class 2 (APC 2): 7 kA, 500 ms, 320 kJ. Resistance is defined as the fact that none of the tested gloves may exhibit an afterburn time > 5 s, melt through to the inside, puncture, or exceed the limits for skin burns according to the Stoll / Chianta criterion, as defined in the standard on which this method is based (IEC 61482 - 1-2). The permissible energy limit curve is shown in Figure 2 as a solid line; the other curves (dotted, dashed, and dash-dot) refer to the energy observed in the respective sensors under the respective tested gloves. Three Class 00 protective gloves, approximately 0.5 mm thick, were tested.The three protective gloves were made of the inventive material consisting of TPEs and pigment, with a pigment content of 0.5% by weight of TPE, and were from three different batches. In Figure 2, one of the curves (dotted, dashed, and dash-dot) corresponds to the measurement result for one glove.

[0096] The protective gloves which are the subject of the present invention and which can be produced using the method according to the invention correspond at least to the described class 1. However, depending on the thickness of the protective gloves, higher protection classes for arc flash protection can be achieved.

[0097] The invention has numerous advantages.

[0098] The process according to the invention enables for the first time the use of TPEs as an alternative to conventional materials used to date for the production of electrically insulating protective gloves.

[0099] By using TPEs and thus making vulcanization obsolete, the gloves do not contain any sulfur-based allergens, as cross-linking additives such as sulfur or sulfur donors are no longer required.

[0100] In contrast to natural rubber, TPEs do not contain any allergenic proteins.

[0101] The product (electrically insulating protective glove with arc flash protection) does not undergo any thermal process (thermosensitive dipping, vulcanization) during production, so the process is energy-efficient.

[0102] Due to the non-chemical change in the materials resulting from the elimination of the vulcanization process (the polymer chains are not cross-linked), the gloves produced in the process according to the invention can be redissolved in organic solvent and used for the production of new gloves.

[0103] The protective gloves manufactured using the process according to the invention meet the technical requirements of the IEC 60903 standard, as confirmed by tests conducted in the AITEX certification laboratory in Spain (see also Figure 1 and Table 2). In particular, the combination of the polymer blend with the pigment provides additional protection against electric arcs according to the standard test based on IEC 61482 - 1-2, tested at West Energie in Dortmund (see Figure 2).

[0104] The protective gloves produced by the method according to the invention can have either a smooth or a rough surface, which allows adaptation to specific activities.

[0105] According to IEC 60903, the protective gloves produced using the process according to the invention are also resistant to ozone, acid and extremely low temperatures.

Claims

PATENT CLAIMS 1. A method for manufacturing electrically insulating protective gloves with arc flash protection, characterized in that the method comprises the following steps: - Providing a starting material consisting essentially of two thermoplastic elastomers; - Dissolving the starting material in an organic solvent to produce a liquid mixture; - Dispersing a pigment in the liquid mixture to produce a dispersion; - Providing at least one mold suitable for the manufacture of protective gloves; - Performing a diving operation comprising at least one cycle consisting of: • a dipping step in which, during an immersion phase, at least one mold is completely immersed in the dispersion and, during an immersion phase, is completely removed from the dispersion to form a layer of material on the mold; and • a drying step to remove the organic solvent from the material layer; - Optional: Evaporation of remaining solvent residues after the immersion process; and - Removing the protective glove thus formed from the at least one mold.

2. Method according to claim 1, characterized in that the two thermoplastic elastomers are based on styrene-ethylene-butylene-styrene (SEBS).

3. Method according to claim 1 or 2, characterized in that the starting material additionally consists of a styrene-based polymeric auxiliary component.

4. Method according to at least one of claims 1 to 3, characterized in that the organic solvent is toluene.

5. Method according to at least one of claims 1 to 4, characterized in that the pigment is an organic pigment, in particular Cu phthalocyanine.

6. Method according to at least one of claims 1 to 5, characterized in that a liquid mixture of 10-50% w / w based on the proportion of the starting material in the organic solvent is produced.

7. Method according to at least one of claims 1 to 6, characterized in that a dispersion of 0.5-10% m / m is produced based on the proportion of the pigment in relation to the starting material.

8. Method according to at least one of claims 1 to 7, characterized in that the method is carried out without vulcanization.

9. Method according to at least one of claims 1 to 8, characterized in that the immersion process consists of 1-50 cycles.

10. Method according to at least one of claims 1 to 9, characterized in that in the immersion step the at least one mold is immersed in the dispersion at a predetermined speed in the immersion phase and is removed from the dispersion at a predetermined speed in the immersion phase.

11. Method according to at least one of claims 1 to 10, characterized in that the at least one mold is constantly rotated during the drying step.

12. Method according to claim 11, characterized in that the at least one mold is rotated at a predetermined rotational speed and / or rotational velocity.

13. Method according to at least one of claims 1 to 12, characterized in that the drying step is carried out for a duration of 20-60 min.

14. Method according to at least one of claims 1 to 13, characterized in that at least part of the starting material and the pigment is replaced by waste material generated in the process and / or protective gloves produced by the process.

15. Method according to at least one of claims 1 to 14, characterized in that the at least one mold has a predetermined surface texture, in particular a smooth surface or a rough surface.

16. Electrically insulating protective glove with arc flash protection, characterized in that the protective glove consists essentially of two thermoplastic elastomers based on styrene-ethylene-butylene-styrene (SEBS) and an organic pigment, in particular Cu-phthalocyanine.

17. Protective glove according to claim 16, characterized in that the protective glove additionally consists of a styrene-based polymeric auxiliary component.

18. Protective glove according to claim 16 or 17, characterized in that the electrically insulating protective glove with arc flash protection meets the requirements of standard classes 00 to 4 according to IEC 60903:2014.