RU2594455C1 - Nonwoven material - Google Patents

Abstract

FIELD: electrochemistry.

SUBSTANCE: invention relates to carbon nonwoven materials, including for use as material for making gas diffusion electrodes of electrochemical current sources. Disclosed is a nonwoven material consisting of two non-woven outer layers and an inner carcass layer including homogeneous viscose fibres, wherein layers are interconnected by needling, inner carcass layer is made of thin fabric with surface density 40-96 g/m², formed by linen weaving of viscose threads at an angle of 90 degrees with linear density of threads of 13-52 Tex with cell size from 1×1 to 4×4 mm , and is laid between non-woven outer layers of viscose fibres with stapling length of not less than 51 mm with surface density of one layer of 58-120 g/m² and number of punctures of 18-30 per 1 cm² and surface density of 36-96 g/m² and number of punctures of 24-48 per 1 cm² for another layer, offset relative to each other by 1.5-2 mm.

EFFECT: technical result is high strength throughout volume of material due to reinforcement of outer layers of nonwoven materials from stapled fibres of sparse fabric formed by linen weaving of viscose fibres, while simultaneously reducing electrical resistance of produced graphite nonwoven materials and maintaining air permeability by forming channels with complex curved shape, which together with through channels form a porous structure with possibility to adjust air permeability and more stable supply of gases into reaction zone during operation of gas diffusion electrodes of electrochemical current sources.

1 cl, 3 tbl, 4 dwg

Description

The invention relates to the field of carbon non-woven materials, including for use as a material for the manufacture of gas diffusion electrodes of electrochemical current sources.

The prior art material obtained by the method of manufacturing a nonwoven needle-punched material reinforced with a mesh, including the formation of the first and second nonwoven layers of the same composition and properties, the location of the mesh of fiberglass with a thread of 34 Tex, mesh size 12 mm in the longitudinal direction and 6 mm for a duck between them [RF Patent 2360050 C2, D04H 1/54, B32B 7/08. A method of manufacturing a nonwoven needle-punched material reinforced with a mesh. 06/27/2009].

The disadvantage of this material is that the fiberglass mesh acts as a reinforcing element, which makes the material unsuitable for processing it into carbon due to the fusibility of glass fibers. This material can serve as the basis for the production of construction, decoration and other similar materials.

The prior art carbon non-woven material and method for its production. Non-woven material made of stapled carbon fibers is obtained by mixing carbon fibers with fusible fibers from resins, followed by compression of the mass and carbonization. The ratio of carbon fibers / fusible fibers is 90 / 10-20 / 80, which ensures the ease of the obtained carbon material [Patent JP 2008081872 A, D01F 9/21; D04H 1/42; D04H 1/60. Carbon nonwoven material and method for its production. 10/10/2000].

The disadvantage of this carbon non-woven material is the use of fusible resins, which results in a non-porous material that cannot be used as a gas diffusion electrode of electrochemical current sources.

Non-woven fibrous materials and their electrodes are known in the art. These nonwoven fibrous materials can be used in various electrochemical devices, hydrogen storage rings, catalytic substrates [RF Patent 2429317 C2, D04H 3/00, D01F 9/12, C25B 11/12, H01M 4/02, H01G 9/04, B32B 9 / 00. Non-woven fibrous materials and electrodes thereof. 09/20/2011].

The disadvantage of these nonwoven fibrous materials is that they consist of fragments of activated carbon fiber, which is brittle and is subject to destruction during operation of the material.

The prior art material obtained by the method of reinforcing non-woven material, paper, cardboard and a device for its implementation, in which the reinforcing material is used roving, yarn, fabric sparse structures [RF Patent 2087609 C1, D21F 1/00; D21H 27/34. A method of reinforcing non-woven material, paper, cardboard and a device for its implementation. 08/20/1998]. The invention relates to the textile industry, to the production of nonwoven materials and can be used in the pulp and paper industry in the production of reinforced paper, cardboard and other materials from fibrous raw materials.

Closest to the claimed is non-woven material [RF Patent 2208074 C1, D04H 1/46, B32B 5/22. Non woven fabric. 07/10/2003], consisting of two non-woven outer layers and an inner frame layer, including homogeneous fibers, the layers being connected by needle piercing (the number of punctures is 120-500 per 1 cm ² ). As the skeleton layer, continuous viscose yarns with a linear density of 192 or 380 Tex, with a strength of 600-800 cN / Tex, laid parallel to each other along non-woven outer layers of viscose stapled fibers with a stapling length of at least 18 mm, are used, the ratio of surface non-woven outer layers and the inner frame layer is (15.5-47.0) :( 1-4) :( 15.5-47.0). The surface density of the nonwoven material is 280-852 g / m ² . Non-woven material is obtained by combining and bonding the outer and frame layers. The outer layers and the base of the skeleton layer are pre-fabricated. The mass of staple fibers is first loosened, then served on a carding machine. A canvas with a surface density of 160-480 g / m ^{2 is} formed from the web. Next, the finished fibrous canvas is fed to the needle-punched stand, where it is subjected to unilateral needle-piercing (the needles are staggered vertically relative to the canvas, the piercing depth is 10-20 mm). The number of punctures is 60-250 per 1 cm ² (60 × 10 ⁴ -250 × 10 ⁴ per 1 m ² ). The basis of the skeleton layer is obtained by parallel winding of threads with a linear density of 192 or 380 Tex on a bobbin in order to obtain a roving. Used continuous filaments capable of withstanding tensile loads of 600-800 cN / tex, on the one hand, play the role of conveyor filaments, and on the other hand, are a structural element of non-woven material, which provides for needle piercing strong engagement of fractions of long staple fibers of the outer layers with continuous threads of the carcass ply. The outer layers of the nonwoven material and the threads of the frame layer wound on bobbins are simultaneously fed to the IM-1800M-A unit, while the threads of the frame layer are laid parallel to each other between the outer layers of the nonwoven material. On the IM-1800M-A unit, all layers are fastened together by needle piercing (the needles are staggered vertically relative to the canvas, the piercing depth is 5-10 mm). The number of punctures is 60-250 per 1 cm ² (60 × 10 ⁴ -250 × 10 ⁴ per 1 m ² ), so the total number of punctures in the nonwoven fabric is 120-500 per 1 cm ² (120 × 10 ⁴ -500 × 10 ⁴ per 1 m ² ). To obtain carbon materials (graphitized), non-woven material is fed to heat treatment in the temperature range from 600 to 2500 ° C. At a temperature of 650 ° C with a gradual increase in temperature at a rate of 10 ° C / min, a carbonized non-woven material is obtained, and then subjected to heat treatment at 1500-2500 ° C, and a non-woven carbon graphite material with the following properties is obtained: strength 240 N density 271 g / m, electrical resistance 1 Ohm, air permeability 85.0 dm ³ / m ² · s.

The disadvantage of this nonwoven material is the unidirectional reinforcement of the outer layers, which leads to uneven strength characteristics in the transverse direction, and a sufficiently high electrical resistance of 1 ohm, obtained graphite material from it. This material in combination of its properties can be used as heat-insulating, electrically conductive and filtering materials.

The technical result of the claimed invention is to eliminate these drawbacks, namely increasing the strength over the entire volume of the material by reinforcing the outer layers of nonwoven materials from stapled fibers with a sparse fabric formed by plain weave of viscose yarns, while reducing the electrical resistance of the obtained graphitized nonwoven materials and maintaining air permeability by forming channels complex curved shapes, which in conjunction with through channels about they form a porous structure with the ability to control air permeability and a more stable supply of gases to the reaction zone during the operation of gas diffusion electrodes of electrochemical current sources.

The specified technical result is achieved in that in a nonwoven material consisting of two nonwoven outer layers and an inner frame layer including homogeneous viscose fibers, the layers being connected by needle piercing, the inner frame layer is made of rarefied fabric with a surface density of 40-96 g / m ² , formed by plain weaving of viscose yarns at an angle of 90 degrees with a linear density of yarns 13-52 Tex with a mesh size of 1 × 1 to 4 × 4 mm, and laid between the nonwoven outer layers of viscose fibers windows with a stapling length of at least 51 mm with a surface density of one layer of 58-120 g / m ² and a number of punctures of 18-30 per 1 cm ² and a surface density of 36-96 g / m ² and a number of punctures of 24-48 per 1 cm ² for another layer, offset from each other by 1.5-2 mm.

Significant differences of the claimed non-woven material are that the inner frame layer is made of rarefied fabric with a surface density of 40-96 g / m ² formed by plain weaving of viscose yarns at an angle of 90 degrees with a linear density of yarns 13-52 Tex with a mesh size of 1 × 1 to 4 × 4 mm, and laid between non-woven outer layers of viscose fibers with a staple length of at least 51 mm with a surface density of one layer 58-120 g / m ² and the number of punctures 18-30 per 1 cm ² and surface density 36 -96 g / m ² and the number of puncture in 24-48 per 1 cm ² for the other layer, offset from each other on 1.5-2 mm, which provides increased strength over the entire volume of the material due to the reinforcing outer nonwoven layers of chopped fibers sparse cloth, plain weave formed by viscose yarns , while reducing the electrical resistance of the obtained graphitized nonwoven materials and maintaining air permeability by forming channels of complex curved shape, which together with the through channels form Risto structure with adjustably breathability and more stable supply of gas to the reaction zone with the gas diffusion electrodes of electrochemical power sources. It is known to use fabrics of rarefied structures for reinforcing nonwoven materials for hardening [RF Patent 2087609 C1, D21F 1/00; D21H 27/34. A method of reinforcing non-woven material, paper, cardboard and a device for its implementation. 08/20/1998], it is also known to use the same non-woven outer layers, between which a fiberglass mesh is placed [RF Patent 2360050 C2, D04H 1/54, B32B 7/08. A method of manufacturing a nonwoven needle-punched material reinforced with a mesh. June 27, 2009], however, the totality of features does not coincide in similar features, material, and the goal achieved. The claimed combination of features with obtaining the above results in the prior art was not found, therefore, the created material has significant differences.

For a better understanding of the invention, a diagram of the nonwoven fabric of FIG. 1 and 2, the finished nonwoven fabric is shown in FIG. 3, FIG. 4 presents a simulated diagram of an electrochemical current source using a gas diffusion electrode obtained by the present method.

Non-woven material (Fig. 3, pos. 8) consists of two non-woven outer layers (Figs. 1, 2, 3, pos. 1, 2) of viscose stapled fibers with a staple length of at least 51 mm and a surface density of one layer 58- 120 g / m and the number of punctures (Fig. 1, 2, pos. 5) 18-30 per 1 cm ² and a surface density of 36-96 g / m and the number of punctures (Fig. 1, pos. 6) 24-48 per 1 cm ² for another layer and offset relative to each other by 1.5-2 mm, and the layers are interconnected by needle-piercing, forming through channels (Fig. 1, 3, item 4), and the inner frame layer (Fig. 1, 2, 3, item 3), represent it is rarefied fabric formed by plain weave rayon filaments at an angle of 90 degrees with a fineness of 13-52 tex with a mesh size of 1 × 1 to 4 × 4 mm. The channels of one layer and the other layer and the through channels formed by needle-piercing to connect the two layers, as well as the displacement of the layers by 1.5-2 mm, form channels of complex curved shape (Fig. 1, item 7).

As the outer layers using fibrous canvas from viscose stapled fibers with the following metric composition, experimentally determined:

51-73 mm long - 24%;

length 74-95 mm - not less than 46%;

96-120 mm long - at least 30%.

The mass of stapled viscose fibers by known methods is preliminarily loosened and fed to a carding machine, where a canvas is formed from the comb. At the same time, fibers 51-95 mm long provide uniform bulk density due to uniform distribution in the weave. Fibers 96-120 mm long, penetrating the entire mass of the obtained webs and subsequently non-woven material, allow us to combine all the fibers of each layer into a single mass of canvas already at the stage of obtaining webs. The characteristics of the outer initial layers after needle piercing are shown in table 1.

One fibrous canvas is subjected to unilateral needle piercing (the needles are staggered vertically relative to the canvas, the piercing depth is 3-4 mm) with the formation of the first layer of material (Fig. 1, 2, 3, item 1). The number of punctures (Fig. 1, 2, 3, item 5) of the first layer is from 6 to 18 per 1 cm ² , while the bulk density of the resulting nonwoven layer is 18-32 kg / m ³ . At the same time, another layer of the inventive nonwoven fabric is prepared. To do this, another fibrous canvas is subjected to unilateral needle piercing (the needles are staggered vertically relative to the canvas, the piercing depth is 3-4 mm) with the formation of another layer of non-woven material (Fig. 1, 2, 3, item 2). The number of punctures (Fig. 1, 2, item 6) of another layer is from 12 to 36 per 1 cm ² , while the bulk density of the resulting non-woven layer is 20-38 kg / m ³ . The ratio of the number of punctures of the outer layers of the material is 1: 2.

As a skeleton layer (Fig. 1, 2, 3, item 3), a sparse fabric formed by plain weaving of viscose yarns at an angle of 90 degrees with a linear density of 13-52 Tex with a cell size of 1 × 1 to 4 × 4 mm is used . The characteristics of the initial frame layer are given in table. 2.

The used sparse fabric formed by plain weaving of viscose yarns, capable of withstanding breaking loads of 60-150 cN / Tex, performs, on the one hand, the role of a conveyor that allows stretching non-woven materials without loss of continuity through all technological stages, starting from the production of reinforced non-woven materials, to stage of the finished carbon product. On the other hand, a sparse fabric is such a structural element of non-woven material that provides, when needle-piercing (Fig. 1, 3, item 4) of all layers, the formation of through channels (Fig. 1, 3, item 4) and strong engagement of fractions of long stapled fibers of the outer layers with a frame layer, so that the resulting reinforced non-woven materials have sufficient strength to produce carbon non-woven materials.

Bonding of the outer nonwoven layers and the inner frame layer is as follows. For this, the outer layers of non-woven material and the carcass layer wound on bobbins are simultaneously fed to the needle-punched unit at the same speed, while the outer layers are displaced relative to each other by 1.5-2 mm (Fig. 1). On the needle-punching unit, all layers are fastened together by needle-piercing (Fig. 1, 3, item 4) (the needles are staggered vertically relative to the canvas, the piercing depth is 3-4 mm), forming vertical through channels (Fig. 1, 3, item . 4), and the displacement of the outer layers leads to the formation of channels of complex curved shape (Fig. 1, item 7). Thus, the total number of punctures in the inventive nonwoven material (Fig. 3, item 8) is from 18 to 48 per 1 cm ² , the properties of nonwoven materials are shown in table 3.

All tests were carried out:

- Determination of strength according to GOST 15902.3-79.

- Determination of electrical resistance according to GOST 11529 - 86.4.2.

- Determination of air permeability according to GOST 12088-77.

The result of the claimed invention is the elimination of these disadvantages of the prototype, namely the increase in strength throughout the volume of the material due to the reinforcement of the outer layers of nonwoven materials from stapled fibers with a sparse fabric formed by plain weave of viscose yarns, while reducing the electrical resistance of the obtained graphitized nonwoven materials and maintaining air permeability by forming channels complex curved shapes, which in combination with through channels They indicate a porous structure with the ability to control air permeability and a more stable supply of gases to the reaction zone during the operation of gas diffusion electrodes of electrochemical current sources.

Example 1. According to the technology indicated above, a nonwoven material with a surface density of 148 g / m ² , bulk density of 90 kg / m ³ , strength of 320 N / 5 cm, air permeability of 100 dm ³ / m ² × s and a thickness of 1.8 is obtained mm (see table 3).

The remaining materials (examples 2-37) were obtained according to the above technology, changes are associated with the types of the outer and frame layers.

From the nonwoven material from example 1 receive graphitized nonwoven material according to the technology described in the prototype. The frame layer of sparse fabric formed by plain weaving of viscose yarns provides increased strength throughout the volume of the material by reinforcing the outer layers of nonwoven materials from stapled fibers while reducing the electrical resistance of the resulting nonwoven graphitized materials and maintaining air permeability by forming channels of complex curved shape, which together with through channels form a porous structure with the ability to control air permeability emosti and more stable supply of gas to the reaction zone with the gas diffusion electrodes of electrochemical power sources. In FIG. 4 is a diagram of a simulated cell of an electrochemical current source, which shows the operation process and obtained the characteristics of the gas diffusion electrode (Fig. 4, item 9), made of graphite non-woven material according to known technology. In the manufacture of gas diffusion electrodes from a nonwoven material, a complex system of through (Fig. 4, pos. 4) and curved channels formed by a combination of channels (Fig. 4, pos. 5, 6) of the outer layers (see Fig. 4, pos. 1, 2) it is preserved (Fig. 4, item 7) and provides a more complete reaction through an increase in the residence time of gases in the reaction zone, which leads to a greater completeness of the reaction 2H ⁺ + 1 / 2O ₂ + 2e ^- = H ₂ O, which provides a large current generated by a chemical current source. The presence of a strong skeleton layer obtained by heat treatment of rarefied fabric from viscose (see Fig. 4, item 3), provides ease of removal of the reaction product - H ₂ O due to channels of complex curved shape. The characteristics of the gas diffusion electrode obtained from the claimed nonwoven material: thickness 0.25 mm, surface density 156 g / m ² , specific resistance 0.03 Ohm · cm, limiting current density 1750 mA / cm.

Claims (1)

Non-woven material, consisting of two non-woven outer layers and an inner skeleton layer, including homogeneous viscose fibers, the layers being interconnected by needle piercing, characterized in that the inner skeleton layer is made of sparse fabric with a surface density of 40-96 g / m ² formed by linen weaving viscose yarns at an angle of 90 degrees with a linear density of yarns 13-52 Tex with a mesh size of 1 × 1 to 4 × 4 mm, and laid between non-woven outer layers of viscose fibers with a staple length of not less than 51 mm from its surface density single layer 58-120 g / m ² and the number of punctures 18-30 per 1 cm ² and an areal density of 36-96 g / m ² and the number of punctures 24-48 per 1 cm ² for the other layer, offset relative to each other by 1.5-2 mm.

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