A novel PPS ultra-fine surface composite filter material and its preparation method

Abstract

The present application relates to the technical field of filter material manufacturing, and in particular to a new type of PPS ultrafine surface composite filter material and a preparation method thereof. The preparation step includes the following steps: S1, a bonding layer for thermal bonding with a PPS ultrafine fiber layer is arranged on a needle-punched grey cloth, a PPS spinning solution is prepared with PPS as a raw material, and the PPS spinning solution is sprayed out by a flash spinning method to form PPS ultrafine fibers and stacked on the bonding layer to form a PPS ultrafine fiber layer; wherein the bonding layer is a PPS fiber layer; S2, the needle-punched grey cloth with a PPS ultrafine fiber layer is subjected to hot rolling treatment, and the hot rolling treatment acts on the PPS ultrafine fiber layer. The finished product prepared by the present application has the advantages of easy cleaning and stable pressure difference, as well as wear resistance and not easy to break. At the same time, it has high filtration accuracy, good mechanical properties and good air permeability. The present application scheme can not only improve the service life of the filter material, but also facilitate the cleaning of the filter material, and can increase the operating time of the dust removal system.

Description

Technical Field

[0001] The present application relates to the technical field of filter material manufacturing, and in particular to a novel PPS ultra-fine surface layer composite filter material and a preparation method thereof. Background Art

[0002] Waste heat flue gas emitted by coal-fired boilers, garbage incinerators and other industries generally contains highly acidic sulfur oxides and nitrogen oxides. Therefore, in the filtration process, the filter material is not only required to have good heat resistance, but also good chemical corrosion resistance and hydrolysis resistance. PPS fiber, also known as polyphenylene sulfide fiber, has excellent acid and alkali resistance and good hydrolysis resistance. It will only degrade under strong oxidants. And its temperature resistance is good. The thermal shrinkage rate of PPS fiber is only 5%-7% below 200℃. When heated at 180℃ for 1000H, its strength retention rate can reach 78%. Therefore, PPS is widely used in the manufacture of filter materials for industrial flue gas dust removal bags.

[0003] The ultra-fine surface filter material forms a layer of PPS ultra-fine fiber on the surface of the filter material. The dust particles in the flue gas will be blocked by the ultra-fine surface layer, and the dust will not enter the inside of the filter material. In this way, the filtration accuracy can be guaranteed, that is, the dust emission concentration is controlled within a smaller range, and the air permeability of the filter material will not be reduced during use, ensuring that the filter material is easy to clean during use. In this way, the operating resistance of the dust removal system can be kept stable and the overall service life of the filter material can be improved.

[0004] To make ultra-fine surface filter material, the key is to obtain PPS ultra-fine fibers. The fiber linear density reaches 0.2-0.5dtex to be called PPS ultra-fine fiber. It is difficult for PPS fibers made by conventional melt spinning methods to be below 1.0dtex. Therefore, it is necessary to explore new spinning methods suitable for preparing PPS ultra-fine fibers.

[0005] The finer fibers obtained by conventional melt spinning are used to manufacture composite filter materials with similar ultrafine structures. For example, the Chinese invention patent "A PPS ultrafine fiber composite needle-punched filter material for steel sintering flue gas and its preparation method" with application number CN201911141439.5 and publication date April 21, 2020 discloses a composite needle-punched filter material, which includes a dust-facing surface layer, a PPS base fabric layer and a bottom layer from top to bottom. The dust-facing surface layer, the PPS base fabric layer and the bottom layer are needle-punched into a grey cloth, characterized in that the dust-facing surface layer is formed by mixing 0.9D*51mm polyphenylene sulfide fiber and 2.0D*51mm polyphenylene sulfide fiber and then being formed by combing and laying, and the bottom layer is formed by mixing 1.2D*51mm polyphenylene sulfide fiber and 2.0D*51mm polyphenylene sulfide fiber and then being formed by combing and laying. The PPS base fabric is sandwiched between the dust-facing surface layer and the bottom layer, processed by needle punching to form a needle-punched fabric, and then processed through a post-processing process to form a composite needle-punched filter material.

[0006] The PPS ultrafine fiber is manufactured by alkali reduction of sea island fibers, and then made into filter material with ultrafine surface layer. For example, the Chinese invention patent "A method for preparing PPS ultrafine fiber composite filter material" with application number CN201410386124.8 and publication date October 29, 2014 discloses a method for preparing PPS ultrafine fiber composite filter material, in which the dust-facing surface layer is blended with PPS / PET sea island composite fiber and PTFE fiber, wherein the weight ratio of PPS / PET sea island composite fiber is 40-60%; the base fabric is made of 100% PTFE filaments interwoven in warp and weft; the clean air surface is made of 100% PPS fiber; the composite needle felt containing PPS ultrafine fiber on the dust-facing surface layer is made by needle punching process, alkali treatment fiber opening and sanding process, and then it is made into PPS ultrafine fiber composite filter material through water spunlace reinforcement and post-finishing treatment.

[0007] The melt-blown method is used to manufacture PPS ultrafine fibers to make filter materials with ultrafine surface layers. For example, the Chinese invention patent "A melt-blown-needle-punched composite preparation method for gradient filter materials and the obtained gradient needle-punched felt" with application number CN202011261822.7 and publication date March 26, 2021 discloses a melt-blown-needle-punched composite preparation method for gradient filter materials. This gradient filter material includes a back dust layer, a support layer, a dust-facing layer and a melt-blown dense layer connected in sequence. The melt-blown spinning method is combined with the needle-punched felt process, especially after the pre-punching machine of the needle-punched felt, a set of melt-blown equipment is added, with ordinary three-layer filter materials as the base material, and a layer of melt-blown PPS ultrafine fibers is evenly sprayed on the surface of the filter material to form a one-time forming process of the gradient filter material, and the surface is trimmed by composite needle-punching at the same time, and finally the gradient needle-punched felt is obtained by singeing, calendering and heat setting.

[0008] The PPS ultrafine fiber is manufactured by electrospinning to produce a filter material with an ultrafine surface layer. For example, the Chinese invention patent "A method for manufacturing a composite filter material of needle puncture / spunlace and electrospinning" with application number CN201310036655.X and publication date May 1, 2013 discloses a method for manufacturing a composite filter material of needle puncture / spunlace and electrospinning, and its manufacturing steps are: firstly, a filter material base is manufactured by needle puncture or hydrospunlace, and the filter material base is composed of three layers: the bottom layer is made of 2.5-7dtex coarse fiber, the middle layer is a sparse fabric base cloth, and the upper layer is composed of 1.0-2.0dtex low melting point fiber and 0.8-2.2dtex fine fiber, wherein the mass percentage of low melting point fiber in the upper layer is 20%-50%; then, a filter material surface layer is manufactured by electrospinning; finally, the filter material surface layer is placed on the filter material base, and a high-performance composite filter material is manufactured by hot rolling. This invention does not use adhesives, but mixes low melting point fibers on the upper layer of the needle-punched / hydroentangled filter material to form a needle-punched / hydroentangled felt base, which is then composited with the electrospun surface layer by hot rolling, and the filter material is formed into a stable structure by heat setting.

[0009] However, the above-mentioned alkali reduction method, melt-blowing method and electrostatic method can only be used to produce ultrafine short fibers, and the strength of the fibers is relatively low. The ultrafine surface layer of the ultrafine surface composite filter material produced has low wear resistance, which is not conducive to the use of the filter material. Summary of the invention

[0010] In order to solve the deficiencies of the prior art mentioned in the above background technology, the present application provides a method for preparing a novel PPS ultra-fine surface layer composite filter material, which comprises the following steps:

[0011] S1. A bonding layer for thermal bonding with a PPS ultrafine fiber layer is arranged on a needle-punched grey fabric, a PPS spinning solution is prepared using PPS as a raw material, and the PPS spinning solution is sprayed out by a flash spinning method to form PPS ultrafine fibers, which are then stacked on the bonding layer to form a PPS ultrafine fiber layer; wherein the bonding layer is a PPS fiber layer;

[0012] S2. The needle-punched grey cloth with the PPS ultrafine fiber layer is subjected to hot rolling treatment. The hot rolling treatment acts on the PPS ultrafine fiber layer, so that the fibers of the PPS ultrafine fiber layer are thermally bonded and consolidated to form a dust-facing surface layer, and the PPS ultrafine fiber layer is thermally bonded to the bonding layer.

[0013] In one embodiment, the needle-punched grey fabric includes a bonding layer, a base fabric layer and a back dust layer in sequence, and the bonding layer and the back dust layer are both short fiber layers; the bonding layer and the back dust layer are reinforced and bonded with the base fabric layer respectively by needle punching to obtain the needle-punched grey fabric.

[0014] In one embodiment, the needle-punched grey fabric comprises a bonding layer, a base fabric layer and a dust-back layer in sequence; and the preparation method of the needle-punched grey fabric comprises the following steps:

[0015] S10, using carding and web laying methods to respectively prepare two layers of fluffy fiber webs with a certain grammage, namely a binding layer and a dust-back layer;

[0016] S20, placing the base fabric layer between the binding layer and the dust back layer, and reinforcing and bonding the binding layer and the dust back layer to the base fabric layer respectively by a needle punching method to obtain a needle punched grey fabric.

[0017] In one embodiment, the bonding layer is a short fiber layer, and its fibers are PPS short fibers; the back dust layer is a short fiber layer, and its fibers are a combination of one or more of PPS short fibers, aramid short fibers, and PTFE short fibers; the base fabric layer is one of PPS woven fabric, PTFE woven fabric, and a blended fabric of PPS and PTFE.

[0018] In one embodiment, the dust-facing surface layer has a gram weight greater than or equal to 30 g / m 2 And less than or equal to 100 g / m 2 ; The weight of the bonding layer is greater than or equal to 100 g / m 2 And less than or equal to 350 g / m 2 ; The weight of the base fabric layer is greater than or equal to 70 g / m 2 And less than or equal to 150 g / m 2 ; The weight of the back dust layer is greater than or equal to 100 g / m 2 And less than or equal to 350 g / m 2 .

[0019] In one embodiment, the fiber fineness of the PPS fiber in the bonding layer is greater than or equal to 1.5D and less than or equal to 8D, and the fiber length is greater than or equal to 38 mm and less than or equal to 78 mm.

[0020] In one embodiment, the fiber fineness of the fibers in the back dust layer is greater than or equal to 1.5D and less than or equal to 8D, and the fiber length is greater than or equal to 38 mm and less than or equal to 78 mm.

[0021] In one embodiment, it also includes a tentering heat setting step; S3, tentering heat setting step: the surface layer prepared in S2 is subjected to a tentering heat setting treatment to obtain a new type of PPS ultrafine surface layer composite filter material. The present application also provides a new type of PPS ultrafine surface layer composite filter material, which is a multi-layer composite structure, which sequentially includes a dust-facing surface layer and a clean air surface layer; the dust-facing surface layer is arranged on the clean air surface layer, and the dust-facing surface layer includes PPS ultrafine fibers prepared by flash spinning; the clean air surface layer includes a bonding layer, a base fabric layer and a dust-back layer, and the bonding layer is arranged under the dust-facing surface layer, and the bonding layer includes PPS short fibers for thermal bonding with the PPS ultrafine fibers; the base fabric layer is arranged under the bonding layer, and the base fabric layer is used to provide filter material support.

[0022] In one embodiment, the back dust layer is a short fiber layer, and its fibers include a combination of one or more of PPS short fibers, aramid short fibers, and PTFE short fibers; the base fabric layer includes one of PPS woven fabric, PTFE woven fabric, and a blended fabric of PPS and PTFE.

[0023] Based on the above, compared with the prior art, the preparation method of a novel PPS ultra-fine surface composite filter material provided in this application has the following beneficial effects:

[0024] The preparation method of the new PPS ultra-fine surface composite filter material provided in the present application has the advantages of easy cleaning and stable pressure difference, as well as wear resistance and not easy to break. At the same time, it has high filtration accuracy, good mechanical properties and good air permeability. The application scheme can not only improve the service life of the filter material, but also facilitate the cleaning of the filter material and increase the operating time of the dust removal system.

[0025] Other features and beneficial effects of the present application will be described in the subsequent description, and partly become apparent from the description, or understood by practicing the present application. The purpose and other beneficial effects of the present application can be realized and obtained by the structures specifically pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. The positional relationships described in the drawings in the following description are based on the directions in which the components are drawn in the diagrams, unless otherwise specified.

[0027] Figure 1 A process flow chart of a method for preparing a novel PPS ultrafine surface layer composite filter material provided in this application;

[0028] Figure 2 A schematic diagram of the structure of the new PPS ultra-fine surface composite filter material provided in this application;

[0029] Figure 3 This is a fiber microscopic image of the dust-facing surface layer of the new PPS ultrafine surface layer composite filter material product obtained in Example 1 provided in the present application.

[0030] Reference numerals:

[0031] 100 new PPS ultra-fine surface composite filter material

[0032] DETAILED DESCRIPTION

[0033] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. The technical features designed in the different implementation modes of the present application described below can be combined with each other as long as they do not conflict with each other. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0034] In the description of this application, it should be noted that all terms (including technical terms and scientific terms) used in this application have the same meaning as those commonly understood by ordinary technicians in the field to which this application belongs, and cannot be understood as limiting this application. It should be further understood that the terms used in this application should be understood to have the same meaning as these terms in the context of this specification and the relevant field, and should not be understood in an idealized or overly formal sense, unless explicitly defined in this application.

[0035] Figure 1 The process flow chart of the preparation method of the novel PPS ultra-fine surface composite filter material 100 provided in this application is combined with Figure 1 As shown, the present application provides a preferred embodiment of the preparation method of the novel PPS ultra-fine surface layer composite filter material 100 as follows:

[0036] It includes the following steps:

[0037] S1. A bonding layer 121 for thermal bonding with a PPS ultrafine fiber layer is arranged on a needle-punched grey fabric, a PPS spinning solution is prepared using PPS as a raw material, and the PPS spinning solution is sprayed out by a flash spinning method to form PPS ultrafine fibers, which are then stacked on the bonding layer 121 to form a PPS ultrafine fiber layer. The bonding layer is a PPS fiber layer.

[0038] Needle punched fabric.

[0039] S2. The needle-punched grey cloth with the PPS ultrafine fiber layer is subjected to hot rolling treatment. The hot rolling treatment acts on the PPS ultrafine fiber layer so that the fibers of the PPS ultrafine fiber layer are thermally bonded and consolidated to form a dust-facing surface layer 11, and the PPS ultrafine fiber layer is thermally bonded to the bonding layer 121.

[0040] Specifically, in the preparation process, the flash spinning method is used to prepare the PPS ultrafine fiber layer as follows: the PPS spinning solution is ejected through the nozzle of the flash spinning device to form PPS ultrafine fibers, and the PPS ultrafine fibers are stacked on the binding layer 121 of the needle-punched fabric, so as to form a PPS ultrafine fiber layer with a certain gram weight on the needle-punched fabric. Then, the needle-punched fabric with the PPS ultrafine fiber layer is subjected to hot rolling treatment, and the hot rolling treatment acts on the PPS ultrafine fiber layer, that is, the hot rolling surface (such as the hot roller surface) of the hot rolling device acts on one side of the PPS ultrafine fiber layer, so that the fibers of the PPS ultrafine fiber layer are thermally bonded and consolidated together to form a dense and smooth surface, that is, the dust-facing surface layer 11, and the PPS ultrafine fiber layer can be combined with the needle-punched fiber layer of the binding layer 121 below by thermal bonding, so that the needle-punched fabric with the binding layer 121 forms a clean air surface layer 12.

[0041] Specifically, the preparation method of the novel PPS ultrafine surface layer composite filter material 100 provided in the present application includes at least the following design principles and inventive concepts:

[0042] The principle of the ultra-fine surface layer, i.e., the dust-facing surface layer 11, for filtering dust is that when dusty industrial flue gas, tail gas and other gases pass through the new PPS ultra-fine surface layer composite filter material 100 provided in this application, the dust is blocked on the outside of the ultra-fine surface layer because the particle size of the dust particles is larger than the pore diameter between the fibers of the dust-facing surface layer 11 (ultra-fine surface layer) of the filter material, while the gas molecules are smaller than the pore diameter of the ultra-fine surface layer and can enter the clean air surface layer 12 formed by the needle-punched grey cloth through the pores of the ultra-fine surface layer. The filtered clean air gas enters the clean air surface layer 12 after passing through the ultra-fine surface layer. The pores of the clean air surface layer 12 are not as small as those of the specially made dust-facing surface layer 11, and its larger pores allow the gas to pass quickly, so that industrial flue gas, tail gas and other gases are filtered.

[0043] The key points of this application are:

[0044] A layer of PPS ultrafine fiber layer is attached to the needle-punched grey cloth by flash spinning technology, and the fibers of the PPS ultrafine fiber layer are thermally bonded and consolidated together by hot rolling to form a dense and smooth surface, namely the dust-facing surface layer 11, and the PPS ultrafine fiber layer can be thermally bonded with the fibers of the lower binding layer 121 to form a composite filter material with an ultrafine layer. Among them, the binding layer 121 is a PPS fiber layer, which is made of the same material as the PPS ultrafine fiber layer, so it can be simultaneously hot-rolled and thermally bonded. The PPS ultrafine fiber obtained by flash spinning is a continuous filament, which can form a PPS ultrafine fiber layer with a smooth surface and a microporous structure after hot rolling and thermal bonding consolidation. This ultrafine surface layer with a smooth surface and a microporous structure is the best choice for flue gas filtration. In addition to having the same effects as the coated filter material: easy to clean and stable pressure difference, it also has advantages that the coated filter material does not have: wear resistance and not easy to break.

[0045] This application innovatively applies flash spinning technology to attach a layer of PPS ultrafine fiber layer on the needle-punched grey cloth, and hot-rolls the PPS ultrafine fiber layer to form a dust-facing surface layer 11. Flash spinning is a spinning method for manufacturing PPS ultrafine fibers. The fibers produced are fine and filamentous, and the linear density can reach 0.1-0.2dtex. The single fiber strength is high, and the PPS ultrafine fibers produced by this method are used to manufacture ultrafine surface filter materials, which has not yet been disclosed. The alkali reduction method, melt-blowing method, and electrostatic method can only be used to manufacture ultrafine short fibers, and the strength of the fibers is relatively low. The ultrafine surface layer of the ultrafine surface composite filter material produced has low wear resistance, which is not conducive to the use of filter materials. The PPS ultrafine fiber surface layer produced by the flash spinning method in the present application is a continuous filament with high strength. In addition, the surface thermal bonding process (hot rolling treatment) is used to produce an ultrafine surface layer with a smooth surface. Unlike the traditional short fiber surface layer which needs to be singed and calendered, the smooth ultrafine surface layer produced by the present application scheme is of great help in improving the filtration accuracy and efficiency of the filter material and reducing the filtration resistance.

[0046] For the preparation of PPS spinning solution:

[0047] Preferably, the method further comprises the step of preparing a PPS spinning solution: mixing and dissolving the PPS chips and a matching solvent under a high temperature and high pressure environment (eg, an autoclave) to obtain a PPS spinning solution of a certain concentration.

[0048] Specifically, PPS chips are added into the high-pressure reactor through a melt metering device and the matching solvent is added through a solvent metering device according to a preset ratio. The high-pressure reactor is heated and pressurized to the preset reaction temperature and pressure state. Under the stirring action of the agitator, the polymer and the solvent are fully dissolved to form a uniform solution (i.e., PPS spinning solution).

[0049] For flash spinning and hot rolling process parameter selection:

[0050] Preferably, in the PPS spinning solution, the mass ratio of PPS chips is greater than or equal to 5% and less than or equal to 20%. Further preferably, the temperature of the PPS spinning solution in the reactor is controlled between greater than or equal to 150°C and less than or equal to 300°C, and the pressure is controlled between greater than or equal to 5MPa and less than or equal to 20MPa. In this way, a uniformly mixed spinning solution can be obtained to ensure that flash spinning can obtain stable, relatively uniform, and smaller PPS ultrafine fibers.

[0051] Preferably, during the hot rolling process, a hot roller with convex points is first used to act on the dust-facing surface layer 11 at a certain temperature and pressure, so that the PPS ultrafine fiber layer obtained by flash spinning is thermally bonded to the bonding layer 121, wherein the hot roller with convex points contacts the dust-facing surface layer 11. Then, a smooth hot roller is used to act on the dust-facing surface layer 11 at a certain temperature and pressure, so that the fibers in the PPS ultrafine fiber layer obtained by flash spinning are thermally bonded, and a smooth surface of the dust-facing surface layer 11 can be obtained at the same time, thereby improving the wear resistance and easy dust cleaning performance of the dust-facing surface layer 11. The temperature range of the hot roller with convex points is greater than or equal to 160°C and less than or equal to 280°C, and the pressure range is greater than or equal to 1.5MPa and less than or equal to 5.0MPa. The temperature range of the smooth hot roller is greater than or equal to 180°C and less than or equal to 300°C, and the pressure range is greater than or equal to 1.5MPa and less than or equal to 5.0MPa.

[0052] For the material and raw material parameters of each layer of the new PPS ultra-fine surface composite filter material 100:

[0053] Preferably, the bonding layer 121 is a short fiber layer, and its fibers are PPS short fibers. The back dust layer 123 is a short fiber layer, and its fibers include a combination of one or more of PPS short fibers, aramid short fibers, and PTFE short fibers. The base fabric layer 122 includes one of PPS woven fabric, PTFE woven fabric, and a blended fabric of PPS and PTFE.

[0054] Preferably, the dust-facing surface layer 11 has a weight greater than or equal to 30 g / m 2 And less than or equal to 100 g / m 2 The weight of the bonding layer 121 is greater than or equal to 100 g / m 2 And less than or equal to 350 g / m 2 The base fabric layer 122 has a weight greater than or equal to 70 g / m 2 And less than or equal to 150 g / m 2 The weight of the dust back layer 123 is greater than or equal to 100 g / m 2 And less than or equal to 350 g / m 2 . With the above arrangement, for the gram weight selection of the dust-facing surface layer 11, if its gram weight is lower than the specified range, the gram weight is too low and the fibers are too few, which is not conducive to maintaining the filtering performance and wear resistance of the prepared filter material. If its gram weight is higher than the specified range, the gram weight is too high and the fibers are too many, which is not conducive to thermally bonding the fibers of the dust-facing surface layer 11 and the fibers of the binding layer 121 by hot rolling, and will reduce the air permeability of the dust-facing surface layer 11, which is not conducive to the filtering performance of the filter material (too much resistance). In addition, the gram weight setting of the binding layer 121, the base fabric layer 122, and the dust-back layer 123 is mainly to provide the mechanical properties of the filter material (skeleton effect). If its gram weight is lower than the specified range, the gram weight is too low, resulting in too low mechanical properties. If the gram weight is too high, the manufacturing cost is too high, resulting in waste.

[0055] Preferably, the fiber fineness of the PPS fiber in the bonding layer 121 is greater than or equal to 1.5D and less than or equal to 8D, and the fiber length is greater than or equal to 38mm and less than or equal to 78mm. Preferably, the fiber fineness of the fibers in the back dust layer 123 is greater than or equal to 1.5D and less than or equal to 8D, and the fiber length is greater than or equal to 38mm and less than or equal to 78mm. As described above, the gram weight setting of the bonding layer 121, the base fabric layer 122, and the back dust layer 123 is mainly to provide the mechanical properties of the filter material (skeleton effect). The bonding layer 121, the base fabric layer 122, and the back dust layer 123 use fibers of the above specifications, which can not only provide better mechanical properties, but also ensure air permeability and the filtering performance of the filter material (easy to clean).

[0056] It should be noted that the fibers of the bonding layer 121 and the dust back layer 123 in the preferred embodiment of the present application may be fibers of one specification, or any combination of multiple fibers of the above specifications.

[0057] For the preparation of needle punched fabrics:

[0058] Preferably, the needle-punched fabric includes a binding layer 121, a base fabric layer 122 and a dust layer 123 in sequence, and the binding layer 121 and the dust layer 123 are both short fiber layers. The binding layer 121 and the dust layer 123 are respectively reinforced and bonded with the base fabric layer 122 by a needle-punching method to obtain a needle-punched fabric. Further preferably, the needle-punched fabric includes a binding layer 121, a base fabric layer 122 and a dust layer 123 in sequence. The preparation method of the needle-punched fabric includes the following steps: S10, using carding and laying methods to respectively obtain two layers of fluffy fiber webs with a certain gram weight, that is, the binding layer 121 and the dust layer 123. S20, placing the base fabric layer 122 between the binding layer 121 and the dust layer 123, and reinforcing and bonding the binding layer 121 and the dust layer 123 with the base fabric layer 122 by a needle-punching method to obtain a needle-punched fabric. Among them, carding is to arrange the messy short fibers into a thin fiber web with consistent orientation, and laying is to cross-lay multiple layers of fiber webs to form a heavy and thick fiber web.

[0059] Among them, the bonding layer 121 below the dust-facing surface layer 11 is a short fiber layer made of PPS, which is used for thermal bonding with the PPS filament fibers of the ultra-fine surface layer. Below the bonding layer 121 is the base fabric layer 122, which provides the skeleton of the filter material to ensure the structural stability of the filter material. The bottom layer is the dust-back layer 123, which is also a short fiber layer. The three layers are combined by water needling to form the clean air surface layer 12. This preferred embodiment combines the flash spinning technology with the needle-punching method to produce short-fiber needle-punched felt filter material (i.e., the needle-punching method to produce needle-punched grey cloth: the bonding layer 121 and the dust-back layer 123 are respectively reinforced and combined with the base fabric layer 122 by the needling method), and uses the flash technology to attach a layer of PPS ultra-fine fiber layer to the needle-punched short-fiber needle-punched felt to form a composite filter material with an ultra-fine layer.

[0060] Among them, the PPS ultrafine fiber obtained by flash spinning is a continuous filament, and the heat rolling treatment makes the fibers of the PPS ultrafine fiber layer thermally bonded and consolidated together to form a dense and smooth surface, namely the dust-facing surface layer 11, and the PPS ultrafine fiber layer can be thermally bonded with the lower needle-punched fiber layer (i.e., the bonding layer 121). After hot rolling treatment and thermal bonding consolidation, a PPS ultrafine fiber layer with a smooth surface and a microporous structure (i.e., the dust-facing surface layer 11) can be formed. The finished product has the above-mentioned ultrafine surface effect, and the bonding layer 121 and the dust-back layer 123 are reinforced and combined with the base fabric layer 122 by a needle punching method to form a needle-punched blank fabric. The needle-punched blank fabric (i.e., the clean air surface layer 12) adopts a conventional needle-punched short fiber needle-punched felt structure, which has good mechanical properties and good air permeability, which can not only ensure the service life of the filter material, but also facilitate dust cleaning and increase the operating time of the dust removal system.

[0061] Preferably, it also includes a tentering heat setting step. S3, tentering heat setting step: the surface layer prepared in S2 is subjected to a tentering heat setting treatment, so as to obtain Figure 2 The novel PPS ultra-fine surface layer composite filter material 100 of the structure shown in the figure. In the tentering heat setting step, the surface layer prepared by S2 is further tentered and heat set to reduce the heat shrinkage rate of the composite filter material and improve its thermal stability, thereby forming a PPS ultra-fine surface layer composite filter material.

[0062] Among them, the new PPS ultra-fine surface composite filter material 100 Figure 2 As shown, the novel PPS ultrafine surface layer composite filter material 100 is a multi-layer composite structure, which sequentially comprises a dust-facing surface layer 11 and a clean air surface layer 12. The dust-facing surface layer 11 is arranged on the clean air surface layer 12, and the dust-facing surface layer 11 comprises PPS ultrafine fibers made by flash spinning. The clean air surface layer 12 comprises a bonding layer 121, a base fabric layer 122 and a dust-back layer 123. The bonding layer 121 is arranged under the dust-facing surface layer 11, and the bonding layer 121 comprises PPS short fibers for thermal bonding with the PPS ultrafine fibers. The base fabric layer 122 is arranged under the bonding layer, and the base fabric layer 122 is used to provide filter material support.

[0063] The present application also provides the following embodiments and comparative examples:

[0064] In order to show the effect of the finished product prepared by the preparation method of the novel PPS ultra-fine surface layer composite filter material 100 of the present application, the following examples and comparative examples are specially provided to reflect the advantages of the preparation method of the novel PPS ultra-fine surface layer composite filter material 100 provided by the present application through the test comparison of the relevant performance parameters of the prepared products.

[0065] Embodiment 1:

[0066] 1. First, a fluffy fiber web of a certain weight is formed by combing and laying, and a bonding layer 121 and a dust back layer 123 are formed respectively. Then, a base fabric layer 122 is placed between the bonding layer 121 and the fiber web dust back layer 123. The two layers of fiber are fully reinforced and combined with the base fabric by a needle punching method to form a needle-punched grey fabric.

[0067] The base fabric layer 122 is a 120g PPS base fabric, the bonding layer 121 is a 200g 2D*60mm PPS short fiber layer, and the dust back layer 123 is a 200g 2D*60mm PPS short fiber layer. The main acupuncture density is 487 needles / cm 2 The needle puncture depth is 8.5mm.

[0068] 2. PPS chips with a mass concentration of 18% and a matching spinning solvent (a mixture of 85% carbon tetrachloride and 15% chloroform) were placed in a high-pressure reactor at 15MPa and 280°C at a stirring rate of 110r / min. After stirring for 3 hours, polyphenylene sulfide (PPS) spinning solution was obtained.

[0069] 3. Prepare PPS ultrafine fibers by flash spinning: The spinning solution prepared in step 2 is sprayed out through a nozzle to form PPS ultrafine fibers, which are laid on the bonding layer 121 of the needle-punched fabric prepared in step 1 to form a PPS ultrafine fiber layer with a certain grammage on the needle-punched fabric.

[0070] The weight of the PPS ultrafine fiber layer is controlled at 50 grams. The process parameters of the flash spinning process are as follows: the spinning solution is ejected from the nozzle at a speed of 13,000 m / min, the spinning solution evaporates quickly, the polymer cools and solidifies, and a PPS ultrafine fiber bundle is formed. The PPS ultrafine fiber bundle settles on the moving needle-punched grey fabric, and the needle-punched grey fabric moves forward at a speed of 35 m / min. The PPS ultrafine fibers are stacked and condensed into a net to form a PPS ultrafine fiber layer.

[0071] 4. The needle-punched fabric with the PPS ultrafine fiber layer prepared in step 3 is subjected to hot rolling. The hot roller surface acts on one side of the PPS ultrafine fiber layer. The heating effect causes the fibers of the PPS ultrafine fiber layer to be thermally bonded together to form a dense and smooth surface, and the PPS ultrafine fiber layer can be thermally bonded to the needle-punched fiber layer of the bonding layer 121 below.

[0072] In the hot rolling process, a hot roller with convex points is first used to act on the dust-facing surface layer 11 at a certain temperature and pressure, so that the PPS ultrafine fiber layer obtained by flash spinning is thermally bonded to the bonding layer 121, wherein the hot roller with convex points contacts the dust-facing surface layer 11. Then a smooth hot roller is used to act on the dust-facing surface layer 11 at a certain temperature and pressure, so that the fibers in the PPS ultrafine fiber layer obtained by flash spinning are thermally bonded, and a smooth surface dust-facing surface layer can be obtained at the same time, thereby improving the wear resistance and easy dust cleaning performance of the dust-facing surface. The temperature of the hot roller with convex points is 240°C and the pressure is 3.5MPa, and the temperature of the smooth hot roller is 260°C and the pressure is 2.0MPa.

[0073] 5. The composite fabric prepared in step 4 is subjected to tentering heat setting to reduce its thermal shrinkage and improve its thermal stability, thereby producing the desired composite filter material.

[0074] Among them, the process parameters of stenter heat setting are: temperature 220℃, vehicle speed 7m / min, and circulating fan power 90%.

[0075] Comparative Example 1:

[0076] Needle-punched coated filter material: 30g PTFE membrane (surface layer) + 210g bonding layer 121 (2D*60mm PPS staple fiber layer) + 120g PPS base fabric layer 122 + 210g dust-back layer 123 (2D*60mm PPS staple fiber layer).

[0077] The manufacturing method is: the PPS short fibers are combed into a web, and the weight of the single fiber web is 30g / m 2 The single fiber web is cross-laid to form a wide web with a gram weight of 210g / m 2 The multi-layer fiber net (i.e., the bonding layer 121 and the dust-backing layer 123) is then placed between the two multi-layer fiber nets, and the base fabric layer 122 is processed into a fluffy needle felt by pre-needling, and then reinforced into a dense needle felt by main needling. The needle felt is formed by tentering and singeing to form a dimensionally stable needle felt. The PTFE microporous membrane is then bonded to the PPS fiber of the singeing surface layer by hot pressing to form a PPS composite filter material with a layer of PTFE microporous membrane on the surface.

[0078] Among them, the process parameters of needle punching reinforcement are: the needle punching density of pre-needling is 135 needles / cm 2 The needling depth is 15.4 mm. The needling density of the main needling is 512 needles / cm 2, the upper needling depth is 8.2mm, and the lower needling density is 8.7mm. The process parameters of stentering are: temperature 220℃, speed 7m / min, and circulating fan power 90%. The singeing process parameters are: speed 10m / min. The hot pressing lamination process parameters are: hot roller temperature 280℃, speed 10m / min, and hot roller pressure 1.6MPa.

[0079] Comparative Example 2:

[0080] Needle punched conventional filter material: 225g of binding layer 121 (2D*60mm PPS staple fiber layer) + 120g of PPS base fabric layer 122 + 225g of dust back layer 123 (2D*60mm PPS staple fiber layer)

[0081] The manufacturing method is: the PPS short fibers are combed into a web, the single fiber web weight is 30g / m2, the single fiber web is cross-laid to form a wide multi-layer fiber web (i.e., the bonding layer 121 and the dust-back layer 123) with a weight of 200g / m2, and then the base fabric layer 122 is placed between the two multi-layer fiber webs, processed into a fluffy needle felt by pre-needling, and then reinforced into a dense needle felt by main needling. The needle felt is then stretched, shaped, singed, and calendered to form a dimensionally stable needle felt, thus forming a conventional PPS filter material.

[0082] Among them, the process parameters of needle punching reinforcement are: the needle punching density of pre-needling is 135 needles / cm 2 The needling depth is 15.4 mm. The needling density of the main needling is 502 needles / cm 2 , the upper needling depth is 8.1mm, and the lower needling density is 8.6mm. The process parameters of stentering are: temperature 220℃, speed 7m / min, and circulating fan power 90%. The singeing process parameters are: speed 10m / min. The calendering process parameters are: hot roller temperature 250℃, speed 10m / min, and hot roller pressure 3.2MPa.

[0083] Comparative Example 3:

[0084] The difference between this comparative example and Example 1 is that the weight of the dust-facing surface layer 11 is 15 g / m 2 .

[0085] Comparative Example 4:

[0086] The difference between this comparative example and Example 1 is that the weight of the dust-facing surface layer 11 is 130 g / m 2 .

[0087] The finished products prepared in the embodiments and comparative examples were tested for relevant performance indicators, and the test results are shown in Table 1 below:

[0088] Table 1

[0089]

[0090] The finished products prepared in the embodiment and the comparative example were tested for wear resistance: the samples of the embodiment and the comparative example were placed on the wear tester, and after being worn 50, 200, and 500 times, the filtering performance of the finished filter material was tested again. The test results are shown in Table 1 below:

[0091] Table 2

[0092]

[0093] In Table 1-2, the test standards or test methods for various properties are as follows: The test standard (or process) for the wear resistance test is: using a Martindale abrasion tester, refer to the national standard GB / T 21196.2, and the test abrasive: using self-made abrasive. Test load: 12kpa. The gram weight test refers to the national standard GB / T24218.1-2009, the thickness test refers to the national standard GB / T24218.2-2009, the air permeability test refers to the national standard GB / T5453-1997, the breaking strength test refers to the national standard GB / T24218.3-2010, and the tear strength test refers to the national standard GB / T3917.3-2009.

[0094] Analyze the results of the embodiments and comparative examples:

[0095] like Figure 3 As shown, in the finished product prepared in Example 1, the fiber micrograph of the dust-facing surface layer 11 shows that the fibers are fine, the fibers on the surface are bonded together, the surface is smooth and dense, and has a microporous structure.

[0096] (1) Comparison results before wear test of Example 1 and Comparative Examples 1-2:

[0097] The air permeability of Example 1 is equivalent to that of Comparative Example 1, but is significantly lower than that of Comparative Example 2. The breaking strength of Example 1 is the best, and Comparative Example 1 is equivalent to that of Comparative Example 2.

[0098] Filtration performance: The filtration efficiency of Example 1 and Comparative Example 1 is comparable, both are relatively good, and significantly better than Comparative Example 2. The initial resistance of Example 1 and Comparative Example 1 is comparable, and significantly greater than that of Comparative Example 2. This is due to the relatively small air permeability of Example 1 and Comparative Example 1, and the relatively large air permeability of Comparative Example 2. However, the residual resistance of Example 1 and Comparative Example 1 is comparable, and significantly smaller than that of Comparative Example 2, indicating that the dust of Example 1 and Comparative Example 1 is filtered on the surface, while the dust of Comparative Example 2 will enter the interior of the filter material, indicating that the running resistance of Example 1 and Comparative Example 1 in the dust removal system is relatively small and relatively stable. The dust stripping rate of Example 1 and Comparative Example 1 is comparable, and significantly better than that of Comparative Example 2, which also indicates that the dust of Example 1 and Comparative Example 1 is filtered on the surface, while the dust of Comparative Example 2 will enter the interior of the filter material.

[0099] (2) Comparison results after wear resistance test of Example 1 and Comparative Examples 1-2:

[0100] The surface of Example 1 is a dense PPS ultrafine fiber layer with the best wear resistance. After being worn for more than 200 times, it still maintains good filtering performance. After more than 500 times, the filtering performance decreases.

[0101] The filtering performance of Comparative Example 1 mainly depends on the PTFE microporous membrane on the surface, which is easily worn. After being worn 50 times, the filtering performance is significantly reduced.

[0102] The conventional needle-punched filter material of Comparative Example 2 has no ultra-fine surface layer (i.e., dust-facing surface layer 11), and has low filtration accuracy, especially for PM2.5 dust, its filtration accuracy is lower than that of Example 1 and Comparative Example 1; during filtration, dust will enter the interior of the filter material, which is not conducive to dust cleaning. After wear, the surface is prone to fuzzing, which is not conducive to dust cleaning, and its filtration performance will be significantly reduced.

[0103] In summary, the preparation method of the new PPS ultra-fine surface composite filter material 100 provided in the present application, the finished product has the characteristics of easy cleaning and stable pressure difference, and has the advantages of wear resistance and not easy to break. At the same time, it has high filtration accuracy, and the filtration efficiency of PM2.5 dust is as high as 99.9999%, with good mechanical properties and good air permeability. In summary, the present application scheme can not only improve the service life of the filter material, but also facilitate cleaning and increase the operating time of the dust removal system.

[0104] (3) Comparison results of Example 1 and Comparative Examples 3-4:

[0105] Compared with the embodiments, the wear resistance and filtration performance of comparative example 3 are significantly deteriorated, the air permeability of comparative example 4 is significantly reduced, and the filtration performance of the filter material is adversely affected because the gram weight is too large and the filter material resistance is too large.

[0106] It should be noted that:

[0107] In this article, "gram weight" refers to the weight of the material per unit area, in g / m 2 .

[0108] Regarding the expression of fiber fineness in this article, its unit D (Denier) is expressed as: the weight of 9000 meters of fiber in grams at the official regain. Denier is abbreviated as denier (D). For example, 9000 meters of fiber weighs 1 gram, which is 1 denier (1D). When the fiber density is constant, the larger the denier, the thicker the fiber. It is often used to express chemical fiber filaments, silk, etc. Although denier is not a metric unit, it is a common expression in this field.

[0109] At the same time, in actual control, technical personnel in this field adjust the process parameters of hot rolling and hydroentanglement according to the applicability of each level of grammage to ensure the performance of the finished product. Specifically, the specific process parameters are determined according to the material, grammage, etc. of the product. The high and low melting points of the materials and the changes in grammage require adjustment of the process parameters to achieve the desired product effect. If the melting point of the material is high, the hot rolling temperature of the hot rolling treatment must be increased accordingly to achieve the desired thermal bonding effect. As the grammage of the material increases, the number of fibers that need to be thermally bonded will increase, and it is necessary to appropriately increase the hot rolling temperature and other parameters in the hot rolling treatment. As the grammage of the material increases, the number of fibers that need to be hydroentangled will also increase, and it is necessary to increase parameters such as the hydroentanglement pressure.

[0110] In addition, those skilled in the art should understand that, although there are many problems in the prior art, each embodiment or technical solution of the present application can be improved in only one or several aspects, without having to solve all the technical problems listed in the prior art or background technology at the same time. Those skilled in the art should understand that the content not mentioned in a claim should not be used as a limitation on the claim.

[0111] Although the terms such as flash spinning, hot rolling treatment, and stenter heat setting are used more frequently in this article, the possibility of using other terms is not excluded. These terms are used only to more conveniently describe and explain the essence of this application. It is contrary to the spirit of this application to interpret them as any additional restrictions. The terms "first", "second", etc. (if any) in the description and claims of the embodiments of this application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0112] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the above embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the above embodiments can still be modified, or some or all of the technical features can be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

[0113] In addition, those skilled in the art should understand that, although there are many problems in the prior art, each embodiment or technical solution of the present application can be improved in only one or several aspects, without having to solve all the technical problems listed in the prior art or background technology at the same time. Those skilled in the art should understand that the content not mentioned in a claim should not be used as a limitation on the claim.

Claims

1. A method for preparing a novel PPS ultrafine surface composite filter material, characterized in that: The following steps are involved: S1. A bonding layer for thermal bonding with a PPS ultrafine fiber layer is arranged on a needle-punched grey fabric, a PPS spinning solution is prepared using PPS as a raw material, and the PPS spinning solution is sprayed out by a flash spinning method to form PPS ultrafine fibers, which are then stacked on the bonding layer to form the PPS ultrafine fiber layer; wherein the bonding layer is a PPS fiber layer; S2, hot-rolling the needle-punched fabric with the PPS ultrafine fiber layer, wherein the hot-rolling acts on the PPS ultrafine fiber layer to thermally bond and consolidate the fibers of the PPS ultrafine fiber layer to form a dust-facing surface layer, and to thermally bond the PPS ultrafine fiber layer to the bonding layer; S3, tentering heat setting step: the dust-facing surface layer prepared in S2 is subjected to tentering heat setting treatment to obtain the novel PPS ultrafine surface layer composite filter material; The hot rolling process is as follows: first, a hot roller with convex points is used to act on the PPS ultrafine fiber layer at a certain temperature and pressure, the temperature range of the hot roller with convex points is greater than or equal to 160° C. and less than or equal to 280° C., and the pressure range is greater than or equal to 1.5 MPa and less than or equal to 5.0 MPa; then, a smooth hot roller is used to act on the PPS ultrafine fiber layer at a certain temperature and pressure, the temperature range of the smooth hot roller is greater than or equal to 180° C. and less than or equal to 300° C., and the pressure range is greater than or equal to 1.5 MPa and less than or equal to 5.0 MPa; The needle-punched grey fabric comprises a bonding layer, a base fabric layer and a back dust layer in sequence; the bonding layer and the back dust layer are reinforced and bonded with the base fabric layer respectively by a needle-punching method to obtain the needle-punched grey fabric; The bonding layer is a short fiber layer, and the fiber is PPS short fiber; the base fabric layer is one of PPS woven fabric, PTFE woven fabric, and a blended fabric of PPS and PTFE; the back dust layer is a short fiber layer, and the fiber is a combination of one or more of PPS short fiber, aramid short fiber, and PTFE short fiber; The dust-facing surface layer has a gram weight greater than or equal to 30 g / m 2 And less than or equal to 100 g / m 2 The binding layer has a weight greater than or equal to 100 g / m 2 And less than or equal to 350 g / m 2 The base fabric layer has a grammage greater than or equal to 70 g / m 2 And less than or equal to 150 g / m 2 The weight of the back dust layer is greater than or equal to 100 g / m 2 And less than or equal to 350 g / m 2 The fiber fineness of the PPS fiber in the bonding layer is greater than or equal to 1.5D and less than or equal to 8D, and the fiber length is greater than or equal to 38mm and less than or equal to 78mm; the fiber fineness of the fiber in the back dust layer is greater than or equal to 1.5D and less than or equal to 8D, and the fiber length is greater than or equal to 38mm and less than or equal to 78mm.

2. The method for preparing the novel PPS ultrafine surface layer composite filter material according to claim 1 is characterized in that: The method for preparing the needle-punched grey cloth comprises the following steps: S10, respectively preparing two layers of fluffy fiber webs with a certain grammage by carding and laying, namely, obtaining the bonding layer and the dust-back layer; S20, placing the base fabric layer between the bonding layer and the back dust layer, and reinforcing and bonding the bonding layer and the back dust layer to the base fabric layer respectively by a needle punching method to obtain the needle punched grey fabric.

3. A new type of PPS ultra-fine surface composite filter material, characterized by: It is a multi-layer composite structure, which includes a dust-facing surface layer and an air-cleaning surface layer in sequence; The dust-facing surface layer is arranged on the clean air surface layer, and the dust-facing surface layer includes PPS ultrafine fibers made by flash spinning; the clean air surface layer includes a bonding layer, a base fabric layer and a dust-receiving layer, and the bonding layer is arranged under the dust-facing surface layer, and the bonding layer includes PPS short fibers for thermal bonding with the PPS ultrafine fibers; the base fabric layer is arranged under the bonding layer, and the base fabric layer is used to provide filter material support; Wherein, the novel PPS ultra-fine surface layer composite filter material is prepared by the preparation method of the novel PPS ultra-fine surface layer composite filter material as described in any one of claims 1-2.

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